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7786972
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[Characteristics of AIDS cases detected at a prison in Barcelona (1991-1993)].
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To describe the cases of AIDS detected in a Barcelona prison. A prospective study. A penitentiary for men in Barcelona. All those inmates who had AIDS or were diagnosed with the illness during their stay in prison during the 36 months between 1/1/1991 and 31/12/93. 220 cases of AIDS (91.7% PVDA), 60% of which were diagnosed in prison. The PVDA were younger (p < 0.0001). There were a greater number of Spaniards among the UDVP (p < 0.01) and among those with tattoos (p < 0.001). The first manifestation of the disease in 53% of the cases was extrapulmonary Tuberculosis. Prisons are key places in the prevention and monitoring of HIV infection. The use of care programmes, including maintenance programmes using Methadone, for drug-dependent patients are recommended. The continuation of programmes tracking Tuberculosis, the main illness related to HIV infection in prison, is also recommended.
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7786963
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Bipolar affective disorder associated with beta-thalassemia minor.
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A family suggesting cosegregation of beta-thalassemia minor and bipolar affective disorder was reported. The monogenic hereditary anemia was surveyed over three generations in this family, and three patients with the beta-thalassemia and the bipolar affective disorder were observed over two generations. The localization of a gene responsible for bipolar affective disorder was discussed on the basis of previous reports.
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7786962
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Anxiolytic effects of chlordiazepoxide blocked by injection of GABAA and benzodiazepine receptor antagonists in the region of the anterior basolateral amygdala of rats.
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The amygdala is a structure that is often implicated in the regulation of anxiety responses. Many studies have shown that injection of benzodiazepines into the amygdala produces an anxiolytic effect. The present study was undertaken to determine whether the anxiolytic effect of administration of systemic benzodiazepine (chlordiazepoxide) might be blocked by local injection of a benzodiazepine receptor antagonist (flumazenil) or GABAA receptor antagonist (bicuculline methiodide; BMI) into the region of the anterior basolateral amygdala (BLA) of rats using an ethologically based test of anxiety, the social interaction test. Injection of flumazenil or BMI into the BLA of rats was found to reverse the anxiolytic effects of peripherally administered chlordiazepoxide. These results suggest a major role for the BLA in mediating the anxiolytic effects of benzodiazepines.
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7786961
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Sensory cortical processing and the biological basis of personality.
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Action-oriented personality traits such as sensation seeking, extraversion, and impulsivity have been related to a pronounced amplitude increase of auditory evoked scalp potentials with increasing stimulus intensity. Dipole source analysis represents a crucial methodological progress in this context, because overlapping subcomponents of the scalp potentials can be separated and can be related to their generating cortical structures. In a study on 40 healthy subjects, it was found that sensation seeking is clearly related to the auditory evoked response pattern (N1/P2-component, stimulus intensities: 60, 70, 80, 90, 100 dB SPL) of the superior temporal plane including primary auditory cortex, but not to that of secondary auditory areas in the lateral temporal cortex. These results support the concept that the serotonergic brain system, which is supposed to modulate sensory processing in primary auditory cortices, is an important factor underlying individual differences in sensation seeking.
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7786960
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A placebo-controlled trial of L-365,260, a CCKB antagonist, in panic disorder.
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The functional role of cholecystokinin in the central nervous system is unknown. The tetra peptide CCK-4 was previously observed to induce panic attacks in a majority of normal volunteers and patients with panic disorder. Furthermore, it had been demonstrated that pretreatment with 10-50 mg of L-365,260, a selective CCKB antagonist, blocked CCK-4 induced panic in patients with panic disorder. Therefore, the present multicenter, placebo-controlled, double-blind trial was designed to investigate the efficacy of L-365,260, a CCKB antagonist, in patients with panic disorder with or without agoraphobia. Following a 1-week, single-blind placebo period, 88 patients were randomized to double-blind treatment in which they received either L-365,260, 30 mg qid, or placebo for 6 weeks. At the dose tested, there were no clinically significant differences between L-365,260 and placebo in global improvement ratings, Hamilton anxiety rating scale scores, panic attack frequency, panic attack intensity, or disability measures. The possible reasons for lack of effect with L-365,260 are discussed.
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7786959
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The relationship between tiredness prior to sleep deprivation and the antidepressant response to sleep deprivation in depression.
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Recently it was hypothesized that the antidepressant response to total sleep deprivation (SD) results from a disinhibition process induced by the increase of tiredness in the course of SD. In the present study, the role of tiredness in the antidepressant response to SD is further investigated. Seventy-two depressed patients scored subjective tiredness and depressed mood three times daily (in the morning, afternoon, and evening) on the days preceding and following SD. It was found that averaged tiredness on the day prior to SD was related to the SD response, when the severity of depression prior to SD had been held statistically constant. Also, when both severity of depression and diurnal variation of mood prior to SD were partialed out, tiredness showed a positive correlation with the SD response: patients who reported a relatively low degree of tiredness on the day preceding SD improved by SD. This result suggests that tiredness has an influence on SD effects, and that this influence is independent from that of the severity of depression. The findings are in accordance with current ideas on the role of tiredness as a mediating factor in the induction of the therapeutic effects of SD.
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7786958
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Diurnal neuroendocrine and autonomic function in acute and remitted depressed male patients.
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This study evaluated diurnal data gathered hourly (1000 to 1800 hours) in males during acute depression and during remission of depression and in age-range/gender-matched normal controls. Mean, peak, variability, and time-course of the noradrenergic metabolite, plasma 3-methoxy, 4-hydroxyphenylglycol [MHPG]), plasma cortisol, and autonomic (mean arterial blood pressure [MAP] and heart rate) variables were examined. Compared to controls, acutely depressed, but not remitted depressed, patients had 1) an earlier plasma MHPG peak, 2) a greater intragroup variability of plasma MHPG, 3) a higher plasma cortisol concentration, 4) a lower MAP, and 5) tended to increase MAP more slowly than did the normal controls. The time course of diurnal heart rate also differed in acutely depressed patients from controls: acutely depressed patients started higher and converged by midday to normal levels. These diurnal data lend limited support to the dysregulation hypotheses of depression that suggest normal circadian rhythmicities are altered or disrupted in acute depression and that peripheral manifestations of central dysregulation normalize in remission of depression.
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7786956
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Estrogen augments serotonergic activity in postmenopausal women.
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To investigate the influence of estrogen replacement on serotonergic activity in postmenopausal women, the serotonin agonist meta-chlorophenylpiperazine (m-CPP) (0.5 mg/kg) was given orally to 18 normal postmenopausal women, 11 of whom were also tested following 30 days' treatment with estrogen transdermal patches (estraderm 0.1 mg). Fifteen normal, healthy women of reproductive status served as a control group. Cortisol and prolactin responses to m-CPP were measured. Without estrogen, the prolactin and cortisol responses of postmenopausal women to m-CPP were blunted compared to those of reproductive women. Estrogen replacement increased the hormonal responses. It is suggested that decreased serotonergic activity in postmenopausal women might contribute to their vulnerability to affective disorders. Estrogen replacement therapy might decrease this vulnerability and might add to the efficacy of serotonergic antidepressants when warranted.
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7786957
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Platelet serotonin markers and depressive symptomatology.
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Dysfunction of brain serotonergic symptoms may be a factor in the mood and behavioral disturbances associated with depression. Platelet serotonin measures represent indirect but easily obtainable indices of brain serotonin function. To examine the specificity of relationships between cognitive and vegetative symptom groupings and platelet serotonin measures, we assessed 35 depressed outpatients using the Hamilton Rating Scale for Depression and collected platelets after a minimum 3-week drug-free period. Platelets were also collected from 14 controls. The results showed that depressed patients had lower platelet serotonin (5-HT) uptake site density values than controls and that 5-HT uptake site density values were inversely correlated with the severity of cognitive symptoms of depression. Platelet 5-HT2 receptor density values were higher in depressed patients than controls, and there was a trend toward a direct correlation between the cognitive symptoms of depression and 5-HT2 receptor density values. Neither platelet measure showed any relationship with the severity of the vegetative symptoms of depression.
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7786955
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Clozapine and seizures.
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Epileptiform EEG changes, myoclonus, and seizures are reported in some patients treated with clozapine. Although these are undesirable side effects, the excitation of specific neuronal networks by clozapine and other neuroleptics may be important for the therapeutic effect of this class of agents. In these experiments, intraperitoneal clozapine 2-16 mg/kg produced dose-related myoclonic jerks in partially restrained rats. Paroxysmal slow waves and spike activity were recorded from implanted electrodes in amygdala, hippocampus, and cortex following higher doses of clozapine, but the EEG abnormalities were not correlated with the myoclonic jerks. Single doses of chlorpromazine (8 and 16 mg/kg) rarely produced myoclonic jerks but provoked generalized tonic seizures in two animals preceded by multiple myoclonic jerks in one. Myoclonus and seizures reflect increased excitability of the central nervous system. It is possible that clozapine and other neuroleptics exert a therapeutic effect by increasing excitability in critical subcortical areas of the brain.
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7786951
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Notifying women of the results of their cervical smear tests by mail: does it result in a decreased loss to follow-up of abnormal smears?
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We undertook a prospective randomised intervention study of the proportions of women with abnormal cytology results who were lost to follow-up in 42 general practices in urban and rural Queensland over 26 weeks. Practices in the intervention group were provided with a redesigned cervical smear request form that allowed patients to provide an address for direct notification from the laboratory by mail. Satisfaction questionnaires sent to the general practitioners in the intervention group showed that most made at least some use of direct notification, and most felt it was worthwhile. For women with an initial result of cervical intraepithelial neoplasia (CIN), there was a loss to follow-up of 23 per cent (95 per cent confidence interval (CI) 11 to 39) among the control group compared to none in the intervention group (upper CI 7 per cent), a highly significant difference (P < 0.001). Mailing cervical screening results to women may reduce the loss to follow-up of those with CIN findings.
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7786950
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Community nutrition education for people with coronary heart disease--who attends?
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A qualitative food-frequency questionnaire was administered by mail to a representative sample of 137 people previously diagnosed with possible or definite myocardial infarct. Seventy-eight percent of subjects returned a completed questionnaire and were subsequently invited to attend local tastings of foods with the National Heart Foundation Tick of Approval. These tastings were organised and promoted with the active involvement of the local branch of the Australian Cardiac Association. The purpose of this study was to measure voluntary participation by people with coronary heart disease in community nutrition education and to identify any self-selection bias with respect to eating habits among the participants. A dietary risk score, which was the proportion of all food choices that were high in fat, was calculated from the data. Eighteen per cent of subjects who answered also participated in the food tastings; there was a statistically significant association between membership of the Australian Cardiac Association and being a participant. Participants had a significantly lower risk score (P < 0.01) after adjustment for age, sex and membership of the association. The results suggest that voluntary participation by people with heart disease in community nutrition education is low and that there is a self-selection bias, with those at highest dietary risk being least likely to attend. The use of existing community networks to recruit participants is also discussed.
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7786949
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Ethnic health workers in primary health care.
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Ethnic health workers were employed to increase the access of communities of non-English-speaking background to health services, but their role has remained unclear in a national health system that has been criticised for being slow to respond to the needs of these communities. Interviews and a questionnaire were used to survey a convenience sample of 40 South Australian ethnic health workers, how they should perform their roles and their ability to fulfil them. Interviews with 11 staff from the New South Wales Ethnic Health Worker Program then provided a broader perspective to the South Australian findings. High-priority roles were to provide help to solve immediate health problems. Roles included providing access as well as services. There were pressures on ethnic health workers to become service providers: clients from non-English-speaking backgrounds expected assistance with a wide range of problems, and mainstream staff lacked competence in meeting these needs. Ethnic health workers' involvement in needs assessment and health agency change was limited by these pressures, by ethnic health workers' separation from the work of mainstream staff and because systematic planning of services to non-English-speaking communities was lacking. The appropriate role for an ethnic health worker is as an access provider, with a greater emphasis on needs assessment and agency change. Agencies need to develop culturally appropriate service plans and training so that ethnic health workers and mainstream staff are better able to work together.
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7786948
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Information for family carers: does it help?
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Family carers in Victoria were identified through a statewide telephone survey in 1993. A total of 976 carers was interviewed and a random sample of approximately one in 10 (n = 103) were offered the Carer Support Kit leaflet. The leaflet details the components of the Carer Support Kit (a Federal Government initiative developed in 1992-93) and informs carers how to apply for it through the Victorian Carers' Association. Approximately three-quarters of these carers accepted the offer, and around a third subsequently applied for the kit. Carers who applied for the kit reported significantly more overload and lower life satisfaction than those who did not apply. Only two-thirds of those mailed the kit (just 23 per cent of the eligible study sample) went on to use it. Those who had not used it reported significantly more negative emotions and health problems than those who used it, suggesting that stress and crises could preclude utilisation of the information. A brief evaluation of the components of the kit is presented; however, findings need to be treated with caution in view of the small sample size.
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7786947
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Soil lead levels in parks and playgrounds: an environmental risk assessment in Newcastle.
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In June 1993 the National Health and Medical Research Council set a national goal for blood lead of below 10 micrograms/dl. There is a need to know if the lead contamination of the urban environment is so high as to put community health at risk. Decisions, including whether soil should be removed and replaced, will have to be made. During the second half of 1993, an environmental assessment of lead contamination of soil within the City of Newcastle was conducted. Samples, 108 from surface soil and 10 from subsurface soil, were taken from public parks and playgrounds in the city area and analysed for lead content. The proportion within and the proportion above the guidelines for soil contamination were reported. Lead concentrations ranged from 25 to 2400 parts per million (ppm); 21 per cent of samples had concentrations higher than the 300 ppm action level, and the geometric mean was 134 ppm. Both the range and the average lead levels were typically no more than, or were even less than, soil lead levels documented for other cities in Australia, the United States and United Kingdom. Although each sampling site was noted, it was not our intention to focus in on individual sites. Indeed, to draw health-risk implications from any one result may be misleading and inaccurate. The results indicated moderate lead contamination of soil that could be controlled by regular top-dressing of soils, the use of bark chip on playground surfaces and by government initiatives aimed at lowering lead levels in petrol.
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7786945
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Aboriginal wellbeing and liquor licensing legislation in Western Australia.
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This paper is based on the results of a project undertaken as the basis for a submission to the committee established to review the Western Australian Liquor Licensing Act 1988. It reports on key issues relating to liquor licensing, as identified by members of regional Aboriginal organisations. Among these issues are the promotion of alcohol consumption and misuse, discriminatory practices by licensees and the police and the need for greater community involvement in liquor licensing decisions. To address these issues, members of the participating organisations proposed: inclusion of a harm-minimisation objective in the Act, education and training programs for the public, licensees and the police, and industry funding for harm-minimisation programs.
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7786946
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Psychological impairment following motor vehicle accidents.
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This study investigated the rate of psychological impairment and stressful life events in survivors of motor vehicle accidents. Fifty-six patients who had been hospitalised because of motor-vehicle-accident-related injuries were reviewed twelve months after the accident. In this sample, 41 per cent of patients reported significant levels of psychological impairment. Patients reporting psychological disturbance were characterised by having more pain, unemployment, substance abuse, avoidance of road transport and compensation claims. Only 44 per cent of patients reporting significant psychological impairment had sought professional help for their conditions. Psychological dysfunction following motor vehicle accidents appears to be a common occurrence, and education of medical personnel and survivors is required to enhance identification and management of this problem.
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7786944
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A prospective cohort study investigating psychosocial predictors of attendance at a mobile breast screening service.
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This study aimed to examine whether knowledge, attitudes and concerns predicted attendance at the mobile Breast X-Ray Programme in Sydney. A cohort study design was used, whereby women were surveyed prior to the implementation of the program, and two years later records were checked to determine whether they had attended for screening. Telephone interviews were sought with randomly selected women aged 45 to 70 years living in the central Sydney area (the screening van's catchment area). A total of 285 women was surveyed (response rate: 50 per cent). Of these, 86 (30 per cent) subsequently attended at the mobile van and 199 did not. Attendance did not appear to be related to any of the following factors: knowledge; attitudes; prior experience; perceived susceptibility and morbid concern in relation to breast cancer; the amount of information about screening mammography to which a woman had been exposed. The results are interpreted in light of methodological considerations plus findings from our other research.
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7786943
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Cervical screening in general practice.
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This study examined the effect of three interventions for encouraging women to have a Pap smear in a general practice: tagging the medical record to remind the doctor to offer a Pap smear, sending an invitation to make an appointment for a Pap smear, and sending an invitation with an appointment to attend for a Pap smear at a special screening clinic staffed by women. The study took place in a university general practice at Lockridge, near Perth. A computerised practice age-sex register provided 2139 women in the age range 36 to 69 inclusive. Of these, 757 were eligible for inclusion in the study and were allocated randomly to one of three intervention groups or a control group. In total, 177 women had a Pap smear during the study. Significantly more Pap smears were taken for the appointment-letter and letter-only groups than the control group (odds ratio (OR) 2.13, 95% confidence interval (CI) 1.34 to 3.57, and OR 1.67, CI 1.01 to 2.77 respectively), but there was no significant difference between the tagged-notes and the control groups. Women who attended the screening clinic rated the experience positively. Attendance, however, was inadequate for the clinic's viability in a private practice.
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7786942
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The SF-36 in an Australian sample: validating a new, generic health status measure.
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The SF-36 is a self-reported, 36-item, generic measure of health status that has been validated for adult age groups in the United States, the United Kingdom and in some non-English-speaking countries. The Australian Bureau of Statistics used it in the 1995 National Health Survey and it has been used in health status measurement, in monitoring health outcomes and in clinical trials. The validity of the SF-36 was examined in the National Centre for Epidemiology and Population Health Record Linkage Study using a sample of 555 respondents to the National Heart Foundation Risk Factor Prevalence Survey in 1989; they were followed up in 1992. Items chosen for the scale had been used in health status assessment and had stood the test of time. The health concepts measured demonstrated good internal consistency. The eight scales of the SF-36 formed factors as predicted in the general health dimensions of physical and mental health. The component scales of the SF-36 demonstrated good discrimination between people with and without health conditions, including those with medical and those with psychiatric types of conditions. Although the SF-36 was a valid measure of general health status among Australian respondents, further work is needed to establish clinical validity and to produce population norms for Australia. Use of the SF-36 will allow Australian and international comparison of health status from the point of view of the users of health services.
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7786941
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Critical path analysis for the management of fractured neck of femur.
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The aim of this study was to determine the effect of a critical path analysis, used as a management tool, on the efficiency of clinical service delivery for patients with a fractured neck of femur. It is a before-and-after study of the medical records of all patients admitted between October 1992 and October 1993 with a primary diagnosis of fractured neck of femur, but excluding patients under 50 years old and those with multiple fractures or metastatic disease. Patients fell into two groups: those admitted in the six months before the introduction of a clinical management program based on a critical path analysis, and those admitted after the introduction of the program in April 1993 (88 program cases and 90 nonprogram cases). A medical records administrator blinded to the program category of the patients independently coded diagnostic data, while other data were abstracted from the clinical notes. The length of stay for a fractured neck of femur declined from a mean of 19.3 days to a mean of 11.0 days (P < 0.0001). The outcome measures were: the distance walked just before discharge from hospital, the discharge destination, and unplanned readmission. These did not change significantly, and the wound infection rate declined during the period of the intervention. The implementation of a clinical management pathway based on a critical path analysis dramatically reduced the length of stay for patients admitted with a fractured neck of femur while maintaining quality of outcomes. Critical path analysis is a useful management tool to improve the efficiency of certain clinical services.
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7786940
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Injury from assault in New Zealand: an increasing public health problem.
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Injury purposely inflicted by other persons is a significant public health problem accounting for approximately 4 per cent of all injury hospitalisations in New Zealand. National injury morbidity data for the years 1979-1988 were examined. These data were used to identify the characteristics of victims of assault who were hospitalised, the nature of the injuries they sustained, and the circumstances in which the injuries were inflicted. The incidence of hospitalisations in 1988 was 73.7 per 100,000 persons per year. A significant increase in the rate of hospitalisations over the decade 1979-1988 was identified. The rates for males were higher than those for females, with males 20-24 years of age most at risk. Maori had higher rates than non-Maori. Fights or brawls were the leading cause of hospitalisation. The most common place of occurrence was private homes, followed by streets and highways, and licensed premises. The findings with regard to age, sex, employment status and use of weapons were consistent with earlier studies. A higher proportion of incidents occurring in the home was attributed to differences in selection of cases between studies. An indication of underreporting by women was attributed to concealment of intentionality, possible owing to fear of reprisal. Standard hospital reporting procedures were proposed as a means of improving identification.
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7786939
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A controlled trial of educational visiting to improve benzodiazepine prescribing in general practice.
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A randomised controlled trial studied the effect of an educational visit on benzodiazepine prescribing. An approximately representative sample of 286 general practitioners was allocated to an intervention or a control group. Rates of benzodiazepine prescriptions were derived from two comprehensive self-report surveys seven months apart. Two months after the first survey the intervention group received an educational visit and supporting material from a doctor or pharmacist, ostensibly unconnected with the surveys. The overall benzodiazepine prescribing rate fell by 23.7 per cent from the first to the second surveys, from 4.93 to 3.76 prescriptions per 100 encounters (P < 0.001). Anxiety and insomnia diagnosis rates also declined from 4.68 to 3.76 per 100 encounters (19.7 per cent). After adjusting for confounders, there was a differential downward trend in prescriptions per diagnosis of insomnia but not to a statistical level. The same was true of initial prescriptions per insomnia diagnosis. In a subsidiary analysis selecting only new insomnia diagnoses, the intervention had a strong effect in reducing initial prescriptions (odds ratio 0.18, 95 per cent confidence interval 0.04 to 0.73). No effect was seen on prescribing for anxiety diagnoses. Educational practice visiting for benzodiazepine prescribing in anxiety, as we conducted it, is not justified in an unselected population of general practitioners. Specific education on prescribing for insomnia is probably useful. Our interpretation of the reduction in benzodiazepine prescribing is that probably there was an effect from self-monitoring alone which overwhelmed a main-analysis intervention effect. Retrospective diagnosis may also have obscured a real intervention effect.
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7786938
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An improved aetiologic fraction for alcohol-caused mortality.
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A method is proposed for estimation of alcohol-caused mortality in which the aetiologic fraction of deaths is derived from an exposure contrast between the 'unsafe' drinker and 'safe' drinker; not between the drinker and the nondrinker. The method is consistent with the objectives of public health intervention in the alcohol education field. The 'safe' drinker is the reference exposure category and aetiologic fractions are obtained for the single categories of a multiple-level exposure scale, using separate relative risks for the 'unsafe' drinker and the nondrinker. Preliminary application of the method to Australian data yields an estimate of the number of deaths caused by misuse of alcohol that is larger than those obtained under the old conceptual model. Thus, the public health importance of unsafe alcohol consumption has been underrepresented.
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7786937
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Predictors of unprotected male-to-male anal intercourse with casual partners in a national sample.
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The focus of the paper is the predictors of unprotected anal intercourse with casual partners among a national Australian sample of homosexually active men. We interviewed by telephone 2583 homosexually active men (sex with a man within the last five years) about their sexual practice, type of sexual partners, human immunodeficiency virus (HIV) test status, attachment to the gay community, knowledge of HIV and acquired immune deficiency syndrome (AIDS) and a range of demographic variables. Logistic regression analyses were used to distinguish men who practised unprotected anal intercourse with casual partners from those who practised safe sex with casual partners. Men who practised unprotected anal intercourse with casual partners were less likely to have a regular male sexual partner than men who practised safe sex with their casual partners. They were less likely to be tertiary educated, more likely to be employed in trade and manual occupations and to live in Tasmania and the Northern Territory. They were less likely to be culturally or politically attached to the gay community. Knowledge of HIV/AIDS also distinguished the men: men with an accurate knowledge of HIV transmission were less likely to engage in unprotected anal intercourse with their casual partners. Several other variables, including age and HIV test status, did not distinguish those who practised safe sex with casual partners from those who practised unprotected anal intercourse with casual partners.
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7786936
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Quitting smoking: estimation by meta-analysis of the rate of unaided smoking cessation.
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The rates (after 12 months' follow-up) of unassisted smoking cessation reported in the literature have varied from 13.8 per cent to 8.5 per cent. A meta-analysis was conducted of the abstinence rates observed in 14 samples of smokers who presented at primary health settings and received either no intervention aimed at smoking or usual care (which involved no deliberate intervention for smoking cessation). The estimated rate of stopping smoking without intervention, over an average 10-month period, was 7.33 per cent. This rate is consistent with others reported in the literature when motivation to quit is taken into account. The estimate provides a baseline to judge the effects of smoking-cessation interventions.
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7786934
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Increase in the self-reported prevalence of asthma and hay fever in adults over the last generation: a matched parent-offspring study.
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The study compared current measures on a population-based cohort of adults with past measures on their parents to determine whether the prevalence of self-reported asthma and hay fever in adults increased between 1968 and the early 1990s. In 1968, 8585 cohort members (99 per cent of eligible Tasmanian 7-year-old school children born in 1961), 16,273 (95 per cent) of their parents (mean age 35 years) and 20,937 siblings completed a questionnaire about asthma and hay fever. In 1991-1993, 1494 members (75 per cent) of a stratified random sample of the cohort (aged 29 to 32 years), 75 per cent resident in Tasmania, were surveyed again. In 1968, the proportion of parents who reported having ever had asthma or attacks of wheezing like asthma was 10.9 per cent, independent of age and sex. In 1991-1993, the estimated adult prevalence of having ever suffered from attacks of asthma or wheezy breathing was 23.2 per cent. The proportion reporting at least one asthma attack within the previous 10 years, 5 years, 2 years, 12 months and 6 months was 17.6 per cent, 16.1 per cent, 14.5 per cent, 13.3 per cent and 10.3 per cent, respectively. For hay fever, the adult prevalence was 19.2 per cent in 1968, and 41.3 per cent in 1991-1993. The self-reported lifetime prevalence of asthma and hay fever among adults in the 1961 birth cohort of Tasmanians was twice as high in 1991-1993 as in their parents 25 years earlier.(ABSTRACT TRUNCATED AT 250 WORDS)
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7786935
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Smoking in New Zealand: a census investigation.
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New Zealand may well be unique in that in the 1976 and the 1981 Censuses of Population and Dwellings, persons over the age of 15 were asked about their cigarette smoking habits. The data are available on the basis of age and ethnicity, enabling an examination of the prevalence of ever-smoking by a cohort born some 80 years before the censuses were taken, at the end of the last century. Thus the effect of ever-smoking on mortality can be calculated. Ever regularly smoking reduced the life expectation of males by 11.7 years and females by 15.6 years. The corresponding reductions for Maori were 19.3 years and 23.8 years. The effect of smoking on health has been of epidemic proportions, notably for the Maori.
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7786928
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Differences in baseline EEG measures for ADD and normally achieving preadolescent males.
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This study was designed as a replication of previous studies describing dynamic EEG differences between behaviorally dissimilar groups. This study is intended as a reference point from which other researchers can continue to establish the EEG correlates of "on-task" behavior. Eight Attention Deficit Disordered (ADD) children and eight Normally Achieving Controls (NAC) were assessed using dynamic EEG measures. Results are reported for the tasks of baseline (eyes open), reading, and drawing as recorded from FZ, CZ, PZ, C3, and C4. Significant amplitude differences between the groups were demonstrated in the theta band (4-8 hertz) during all tasks and for all sites. Amplitude differences in the beta band (12-20 hertz) were negligible. Differences between groups expressed as a ratio of theta/beta revealed significant differences mainly in the parietal region for on-task conditions. These results are discussed in relation to EEG neuro-feedback training paradigms and the importance of establishing normative "on-task" EEG values.
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7786929
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Evaluation of the effectiveness of EEG neurofeedback training for ADHD in a clinical setting as measured by changes in T.O.V.A. scores, behavioral ratings, and WISC-R performance.
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A study with three component parts was performed to assess the effectiveness of neurofeedback treatment for Attention Deficit/Hyperactivity Disorder (ADHD). The subject pool consisted of 23 children and adolescents ranging in age from 8 to 19 years with a mean of 11.4 years who participated in a 2- to 3-month summer program of intensive neurofeedback training. Feedback was contingent on the production of 16-20 hertz (beta) activity in the absence of 4-8 hertz (theta) activity. Posttraining changes in EEG activity, T.O.V.A. performance, (ADDES) behavior ratings, and WISC-R performance were assessed. Part I indicated that subjects who successfully decreased theta activity showed significant improvement in T.O.V.A. performance; Part II revealed significant improvement in parent ratings following neurofeedback training; and Part III indicated significant increases in WISC-R scores following neurofeedback training. This study is significant in that it examines the effects of neurofeedback training on both objective and subjective measures under relatively controlled conditions. Our findings corroborate and extend previous research, indicating that neurofeedback training can be an appropriate and efficacious treatment for children with ADHD.
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7786927
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The relationship of expectancies to outcome in stress management treatment of essential hypertension: results from the Joint USSR-USA Behavioral Hypertension Project.
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Outcome expectancy and efficacy expectancy measures were made during the course of a cross-cultural comparison of thermal biofeedback and autogenic training as treatments for mild essential hypertension. There were no differences between groups at either pre- or posttreatment, and expectancy measures were not related to initial success or failure at the completion of treatment. However, both outcome and efficacy expectations were related to relapse over the three months immediately following the completion of treatment. Treatment failures had lower ratings for both outcome and efficacy expectations at the posttreatment assessment in comparison to treatment successes. Implications of these results are discussed.
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7786926
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Electromyographic recordings of paraspinal muscles: variations related to subcutaneous tissue thickness.
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The aim of this study was to assess the effect on EMG amplitude measures of variations in the thickness of underlying tissue between surface electrodes and the active muscle. 20 normal subjects with different amounts of subcutaneous tissue performed comparable constant force contractions for a 45-second period, during which paraspinal EMG recordings were taken. Three measures of subcutaneous tissue thickness were obtained from each subject: Body Mass Index, total body fat as calculated by Durnin's formula, and skinfold thickness at the recording sites. The results show that (i) the greater the thickness of subcutaneous tissue between the surface recording site and the contracting muscles, the lower the recorded electromyographic activity, and that (ii) up to 81.2% of the variance in the EMG measures can be explained by variation in the amount of subcutaneous tissue. These findings support the view that the absolute level of surface-recorded EMG cannot simply be taken at face value. The amplitude of the signal will be affected by, for example, the amount of body fat.
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7786925
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Assessment of lumbar EMG during static and dynamic activity in pain-free normals: implications for muscle scanning protocols.
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The purpose of this study was to provide a thorough description of lumbar surface integrated electromyography (EMG) in pain-free normals during a standardized assessment protocol of static isometric and unresisted dynamic tasks. It has been proposed that in pain-free normals, symmetrical tasks that bend the trunk forward or extend the trunk backward produce symmetrical paraspinal EMG activity, and asymmetrical tasks that rotate or laterally bend the trunk produce asymmetrical paraspinal EMG activity. In addition, it has been observed that lumbar EMG assessment during static tasks has been more consistent than tasks involving dynamic activities. Twenty-eight pain-free normals were assessed during symmetrical and asymmetrical tasks in both static and dynamic activities in a counterbalanced manner. The assessment of paraspinal EMG patterns was conducted while subjects were secured in a triaxial dynamometer, which provided standardization of body position and concurrent measurement of torque, range of motion, and velocity. The results provided experimental evidence for the above-stated propositions. An implication derived from this research is that clinicians may be better served utilizing local norms when using EMG for classification purposes.
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7786924
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Reliability of psychophysiological responding as a function of trait anxiety.
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This study examined the temporal stability of three psychophysiological responses (frontal electromyographic activity, hand surface temperature, and heart rate) recorded over four sessions (days 1, 2, 8, and 28) on 34 subjects, 17 with high Spielberger Trait Anxiety Inventory scores and 17 with low scores. Each session consisted of a 20-minute adaptation period, a baseline condition, and two stressors (one cognitive, the other physical). Two forms of reliability coefficients were employed, intraclass correlations and Pearson Product Moment; the two types of reliability coefficients arrived at the same conclusions. Results indicated that reliability coefficients for the two anxiety groups did not differ on frontal EMG or heart rate responses; however, hand surface temperature responding was considerably less reliable for high anxious individuals than low anxious individuals. Reliability coefficients on absolute scores were, for the most part, reliable. Treating the responses as relative measures (percent change from baseline or simple change scores from baseline) produced smaller and less reliable coefficients. Magnitudes of the three physiological responses did not significantly differ as a function of high or low trait anxiety. Findings are discussed in terms of their clinical, as well as basic psychophysiological, importance.
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7786923
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Improving radioimmunotargeting of tumors: the impact of preloading unlabeled L6 monoclonal antibody on the biodistribution of 125I-L6 in rats.
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In the radioimmunotherapy of malignancies the uptake of monoclonal antibodies (MoAb) is commonly low in tumors compared with normal tissue. Several methods have been suggested to increase the tumor-to-normal tissue (T/N) ratio. In this study we have investigated the biodistribution of different amounts of 125I-L6-biotin MoAb in combination with a preload of unlabeled L6 MoAb. Nude rats were injected with 50 micrograms or 250 micrograms of unlabeled L6 24 hours prior to the injection of 10 micrograms, 50 micrograms or 250 micrograms of 125I-L6, antipancarcinoma MoAb. Dissections were performed 24 hours after the injection of radiolabeled MoAb. The maximal enhancement of tumor uptake with simultaneously decreased uptake in normal tissues was with 250 micrograms of 125I-L6 preceded by a preload of 50 micrograms unlabeled L6. Mean T/N ratios were improved by a factor of 2.9 for bone marrow, 3.4 for liver, 3.7 for lungs and 2.3 for kidneys as compared with the corresponding controls. This study demonstrated that preinjection of optimal amounts of unlabeled L6 MoAb may increase the uptake of 125I-L6 by tumor and improve the T/N ratios. Based on present data, preloading with unlabeled MoAb should be considered in future clinical studies with immunoconjugates to improve the radioimmunotargeting of tumors. It is essential to titrate an appropriate amount of the preload, thus avoiding possible tumor antigen saturation of unlabeled MoAbs but simultaneously decreasing the uptake of subsequently injected radiolabeled MoAb in normal tissues.
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7786922
|
Micronuclei and 3AB-index in patients receiving iodine-131 therapy.
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In 28 blood samples from 21 patients undergoing 131I treatment after surgical thyroidectomy for cancer, the micronucleus (MN) frequency observed in peripheral blood lymphocytes (MN-test on binucleated cells) had a weighted mean of 0.044 +/- 0.006 (SEM), which was significantly different (p < 0.001) from that observed in 93 healthy individuals (0.025 +/- 0.001). The MN frequency (F(MN)) of the patients correlated fairly well (R = 0.736) with the modified activity (Amod) calculated by the following equation: [formula: see text] where Ai is the 131I activity on a determined day, e the logarithm base, di the number of days that have passed between the determined day and the day when the blood was drawn, and k is a day coefficient, defined in this context as the "daily attenuation factor". The use of the value of 0.0003 for k allowed the following equation to be obtained: F(MN) = 7.9 x 10(-5) (+/- 1.4 x 10(-5)).Amod + 0.014 (R = 0.736) The MN frequency was used to estimate, by our DOSIME program, the dose (Gy) received at the individual level in the 131I treatment. In these subjects the calculated dose was well correlated with Amod by the relationship: DBio = 0.0009 (+/- 0.0002).Amod + 0.0675 (R = 0.755) 3-aminobenzamide (3AB), an inhibitor of the poly(ADP-ribose)polymerase enzyme involved in DNA repair, induced and increase in X-ray cytogenetic damage (MN yields), evaluated at the individual level using the 3AB-index (I-3AB). The index was obtained from the MN-yield count after x-irradiation with (MN + 3AB) and without (MN - 3AB) 3AB, using the following formula: I = 1-(MN - 3AB/MN + 3AB).(ABSTRACT TRUNCATED AT 250 WORDS)
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7786921
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A bioimaging integration system implemented for neurological applications.
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A system aimed at the management and fusion of multimodal biomedical images, including X-ray computed tomography, magnetic resonance imaging, positron emission tomography, and single photon emission computed tomography, has been implemented for neurological applications. This bioimaging integration system (BIS) consists of a network for image transmission from acquisition machines to dedicated image processing workstations, a software library for image standardization, and an image registration technique to project multimodal volumetric images into a common reference space. The registration procedure was evaluated in MRI/PET correlation studies, in which misalignment errors of 2.6 mm in the xy transaxial plane and 3.4 mm along the z axis were found. BIS has been validated for the anatomical-functional correlation analysis of MRI and PET images in neurological research protocols and clinical studies.
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7786920
|
111In-octreotide uptake in granulomatous and tumor lesions in a patient with small-cell lung cancer.
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A case of a patient with small cell lung cancer and right submandibular node enlargement due to granulomatous lymphadenitis is presented. Diagnostic procedures included: biopsy of the cervical node, transmission computed tomography of the chest, bronchoscopic examination and biopsy of the pulmonary lesion. The patient underwent 111In-octreotide scintigraphy (whole body and single photon emission tomography) which revealed both lesions. We conclude that granulomatous lesions are to be considered as a possible cause of false positive results, when octreotide scintigraphy is used to evaluate distant metastases in patients with known cancer.
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7786918
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Different tracers and stressors in patients with coronary artery disease: how to standardize clinical questions and nuclear cardiology answers.
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The recent introduction of new tracers and stressors has increased the number of combinations of techniques that can be used for the diagnostic and prognostic stratification of patients with coronary artery disease. However, these new techniques still need to be standardized for clinical use. Thallium-201 scintigraphy is at present the most common method to assess transient ischemia and viability in patients. Dynamic exercise and dipyridamole show similar incidence of major cardiac complications and their use can be considered sufficiently safe. Further experimental and multicenter clinical studies are needed for 99mTc-Sestamibi and 99mTc-Teboroxime and for new stressors such as adenosine and dobutamine.
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7786917
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Determination of glomerular filtration rate with 99mTc-DTPA in clinical practice.
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In order to assess the practical reliability of glomerular filtration rate (GFR) determination with 99mTc-DTPA and plasma sampling, the authors compared the results obtained with 51Cr-EDTA and 99mTc-DTPA in 50 patients using five easily applied methods (two double-plasma-sample methods and three single-plasma-sample methods), and two kits with different compositions. It was observed that: 1) there is no difference between the results obtained with the two different kits. 2) Compared with 51Cr-EDTA the 99mTc-DTPA overestimates the result by about 2 mL/min: precision is slightly lower with 99mTc-DTPA than with 51Cr-EDTA but is sufficient for practical use. 3) The method recommended by the authors on the basis of this experience is the Russell's method with two samples. 4) The simplified methods with one sample give comparable results to the Russell's method for GFR levels between 50 and 115 mL/min, while the results are unsatisfactory below 50 mL/min. 5) Among the single-sample methods, the authors suggest that of Christensen and Groth. 6) A preliminary estimate of GFR (from the serum creatinine level, for instance) is useful for the choice between double-plasma-sample methods and simplified methods. In conclusion, the authors consider that the estimation of GFR with 99mTc-DTPA can be performed efficiently in clinical practice even when operating in absolutely routine conditions.
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7786916
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Locating neuroblastoma in the opsoclonus-myoclonus syndrome.
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We examined the role of various medical imaging modalities, particularly metaiodobenzylguanidine (MIBG) scintigraphy in the investigation of patients presenting with the opsoclonus-myoclonus syndrome (OMS) who may harbor neuroblastomas. A retrospective analysis was therefore performed of all patients presenting with OMS in a 5 1/2 year period. Between December, 1988 and May, 1994, all 13 patients (mean age 15.2 months, range 3 days-30 months) presenting with OMS were extensively studied. A wide range of medical imaging modalities including CT, MRI and [131I] or [123I]-metaiodobenzylguanidine (MIBG) scintigraphy (total of 21 scans) were examined as a means of detecting a structural brain lesion or locating a neuroblastoma, a tumor generally found in less than half of patients with OMS. As anticipated a minority of patients (4) were eventually found to harbor neuroblastomas. In these four cases, two tumors were revealed on preoperative MIBG scintigraphy, one gave a false negative study and one tumor was not studied preoperatively. Each patient was also subjected to extensive radiological investigations in addition to MIBG scintigraphy, many of which were repetitive, redundant or had low clinical yield. The relative merits of the various procedures are compared, and an algorithm incorporating MIBG scintigraphy and limited central nervous system and abdominal anatomical modalities for the investigation of opsoclonus-myoclonus is suggested.
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7786915
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Rest distribution of 99mTc-MIBI in patients with coronary artery disease assessed by SPECT: comparison with the distribution of [18F]FDG assessed by PET.
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The distribution of 99mTc-methoxy-isobutyl-isonitrile (99mTc-MIBI), assessed by single photon emission computed tomography (SPECT) was compared to the distribution of 2-[18F]-2-deoxy-D-glucose ([18F]FDG) assessed with positron emission tomography (PET) under fasting conditions, in 21 patients with coronary artery disease (CAD) and severe left ventricular dysfunction in order to evaluate the potential usefulness of SPECT/99mTc-MIBI for the identification of viable myocardium. Stress and rest SPECT/99mTc-MIBI studies were scored based on the percent of 99mTc-MIBI uptake defined by semi-quantitative circumferential-profile analyses. PET metabolic studies with [18F]FDG under fasting conditions, were adopted as a standard of viability. The results of the comparison of 99mTc-MIBI and [18F]FDG distribution showed that among the segments with stress hypoperfusion, [18F]FDG uptake was present in 95% of the segments that had > 40% of the peak tracer uptake at the rest SPECT/99mTc-MIBI study. [18F]FDG uptake was also present, however, in 25% of the segments that had < 40% uptake at the rest SPECT/99mTc-MIBI scintigraphy. We conclude that in patients with CAD the pattern of 99mTc-MIBI distribution appears to underestimate the extent of viable myocardium but only in those regions that are very severely hypoperfused.
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7786913
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Nocturnal myoclonus syndrome (periodic movements in sleep) related to central dopamine D2-receptor alteration.
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The nocturnal myoclonus syndrome (NMS) consists of stereotyped, repetitive jerks of the lower limbs that occur during sleep or wakefulness. NMS is often related with restless-legs syndrome (RLS) and can cause severe sleep disturbances and daytime sleepiness. The efficacy of dopamine agonists in the treatment points to a dopaminergic dysfunction in NMS. We investigated the central dopamine D2-receptor occupancy with [123I] labeled (S)-2-hydroxy-3-iodo-6-methoxy-([1-ethyl-2-pyrrolidinyl]methyl) benzamide (IBZM) (a highly selective CNS D2 dopamine receptor ligand) ([123I]IBZM) and single photon emission tomography (SPET) in 20 patients with NMS and in 10 healthy controls. In most of the patients with NMS there was a lower [123I]IBZM binding in the striatal structures compared to controls. The results indicate that NMS is related to a decrease of central D2-receptor occupancy.
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7786914
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Radionuclide ventriculography in dynamic cardiomyoplasty.
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Dynamic cardiomyoplasty improves ventricular function by increasing pump function and by limiting cardiac dilatation. The aim of this study was to assess long-term myocardial performance by radionuclide ventriculography on dilated cardiomyopathy patients subjected to cardiomyoplasty. Thirteen survivors were included. Radionuclide ventriculography was performed one week before surgery and one year later. Five patients were also studied two years following surgery. The left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and ventricular amplitude ratio (VAR) to assess mitral regurgitation were measured. Every case after one year showed a non-significant increase in LVEF. However, the decrease in EDV and in VAR was significant (p < 0.01). No significant difference in these values was found after two years. We conclude that the effects of cardiomyoplasty--reduction of cardiac dilatation, wall stress and mitral regurgitation--are more evident during the first year after surgery. Thereafter, a certain stabilization is observed.
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7786910
|
Psychiatric morbidity among repatriated Greek migrants in a rural area.
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This paper reports on psychiatric case identification by the application of the Structured Clinical Interview for DSM-III-R (SCID) in a sample of 198 Greek migrants repatriated from western europe in a northwestern province of Greece. The current (1 month) prevalence of psychiatric morbidity, based on the total number of diagnosed cases, was found to be 43.4%. Lifetime prevalence of psychiatric disorders was found to be higher (49.4%). The majority of the sample were diagnosed as suffering from anxiety disorders and dysthymia. Psychiatric disorders were found to be more prevalent among middle-aged respondents. Duration of stay in the foreign country was a factor correlated with psychiatric morbidity. Of short-term migrants 54% were found to suffer from specific nosological entities, whereas 32% of long-term migrants were diagnosed as cases. The results are discussed within the framework of the existing sociocultural context of emigration and repatriation.
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7786909
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Nonlinear analysis of sleep EEG in depression: calculation of the largest lyapunov exponent.
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Conventional sleep analysis according to Rechtschaffen and Kales (1968) has provided meaningful contributions to the understanding of disturbed sleep architecture in depression. However, there is no characteristic alteration of the sleep cycle, which could serve as a highly specific feature for depressive illness. Therefore, we started to investigate nonlinear properties of sleep electroencephalographic (EEG) data in order to elucidate functional alterations other than those obtained from classical sleep analysis. The application of methods from nonlinear dynamical system theory to EEG data has led to the assumption that the EEG can be treated as a deterministic chaotic process. Chaotic systems are characterized by a so-called sensitive dependence on initial conditions. This property can be quantified by calculating the system's Lyapunov exponents, which measure the exponential separation of nearby initial states in phase space. For 15 depressive inpatients (major depressive episodes according to DSM-III-R criteria) and 13 healthy controls, matched in gender, age, and education, we computed the principal Lyapunov exponents L1 of EEG segments corresponding to sleep stages, I, II, III, IV, and rapid eye movement (REM), according to Rechtschaffen and Kales, for the lead positions CZ and PZ. We found statistically significant decreased values of L1 during sleep stage IV in depressives compared with a healthy control group.
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7786907
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Intelligence and temperament as protective factors for mental health. A cross-sectional and prospective epidemiological study.
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The Sjöbring system of personality dimensions measuring intellectual capacity, activity, impulsivity and sociability was used to study possible "salutogenic" (i.e. causes of health) effects. The study comprised 590 subjects investigated in 1947, 1957, 1972 and 1988-1989 in the Lundby project, an epidemiological study in Sweden. Psychiatric diagnoses were made in 1947, 1957 and 1972. Mental health was estimated in 1988-1989 using the concept "love well, work well, play well and expect well". The Sjöbring dimensions were clinically assessed in 1972. Both in the concurrent study in 1972 and in the prospective study in 1988-1989 "super capacity" (high intellectual function), "super validity" (high activity level) and "super solidity" (low impulsivity) were statistically associated with lower frequencies of certain psychiatric diagnoses and a higher frequency of positive mental health. These variables are proposed to increase coping capacity, and therefore increase stress resilience.
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7786908
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Factors affecting public attitudes towards mental health care.
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This study presents a telephone survey of 501 randomly sampled residents of the Grand Duchy of Luxembourg older than 15 years of age. The interviewees were questioned on their attitudes and judgements towards mental health care in Luxembourg. The implementation of a community-based mental-health-services delivery system in Luxembourg is in its initial stages. Being the smallest member of the European Community Luxembourg offers the opportunity to analyze a whole catchment area in transition marked off clearly by national borders. As a general rule the people of Luxembourg are undecided when it comes to mental health care. Almost half of the sample answered "don't know" when asked about the quality of several sectors of mental health care, excluding inpatient care. The factors that had a significant influence on the attitude of the people of Luxembourg regarding mental health care were nationality, age, class and personal contact with mentally ill persons, with a tendency of worse judgements in younger age groups and in members of upper social classes. We fitted multivariate models including these variables. The results of our study point to entrenched prejudice. The findings suggest, however, that attitudes are changeable by direct or indirect contact with mentally ill persons. Possible strategies that could change public attitudes towards mental health care in a mental health care system that is in transition are discussed.
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7786906
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A set of male monozygotic triplets with schizophrenic psychoses: nature or nurture?
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A set of schizophrenic male monozygotic triplets is described. At age 20 years, within 8 months the three men independently developed acute fulminant schizophrenic disorders (DSM-III-R) with auditory hallucinations, bizarre delusions, and thought disturbances. There were also great similarities between the triplets with regard to the chronic intermittent course of the disorder, impairment of social adjustment, and loss of working ability. The psychoses responded rapidly to conventional neuroleptic treatment. Neuropsychological assessment demonstrated similar marked reductions of attentional, mnestic, and executive functions. Magnetic resonance imaging (MRI) showed similar borderline ventricular enlargement and widened subarachnoid spaces over frontoparietal and basal regions as well as around the pituitary gland (empty sella). All the boys also had a right-sided hearing defect with a marked reduction of the ossicular bones on the right side. Possible clues as to etiological mechanisms were the lack of reported family history for the disorder and a possible influenza infection in the mother during the first trimester. It is suggested that a DNA aberration being present or occurring at conception initiated a precise time-programmed series of events that produced the very similar schizophrenic phenotypes. Such an aberration might have been induced by an external agent, occurred spontaneously, or been inherited by a recessive mechanism. It seems possible that the psychoses, the reductions of neuropsychological functions, the morphological MRI changes, and the right-sided ossicular reductions may all be related to such a DNA alteration.
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7786904
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Species-specific polymorphism in the promoter of the apolipoprotein A-I gene: restoration of human transcriptional efficiency by substitution at positions -189, -144 and -48 bp.
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Previous studies indicate that species-specific differences in apolipoprotein A-I (apo A-I) expression could be largely explained by cis-acting factors located within or near the 5' flanking region (-231 to +223 bp, where +1 is the start site of transcription). In the present studies, we have localized 7 sites within the (-231 to -15 bp) region of the African green monkey apo A-I gene that differ from the human apo A-I gene 5' flanking region. To identify which of the 7 polymorphic sites were essential for the species-specific differences in apo A-I gene expression, mutated promoter constructs were transfected into HepG2 cells and reporter gene expression was measured. Each of the 7 sites within a defined 5' flanking region of the human gene was individually mutated to the African green nucleotide sequence found at that position. Three of the sites (-189, -144 and -48) were found to raise the human apo A-I promoter activity to approx. 60-65% of the African green promoter. While double mutations (-144/-48 bp and -189/-144 bp), restored the human apo A-I promoter activity to 100% of that found with the African green monkey promoter. Additional studies revealed similar DNA: protein interactions with DNA probes from either human or African green monkey and HepG2 cell nuclear extract. In conclusion, these studies demonstrate that double and triple nucleotide substitutions within the human apo A-I promoter are sufficient to restore gene expression in HepG2 cells to levels seen with the African green monkey promoter. These data suggest that sites -189, -144 and -48 bp are involved in significantly altering the binding affinity of a nuclear factor determining the species-specific level of apo A-I gene transcription.
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7786905
|
Lipase from Chromobacterium viscosum: biochemical characterization indicating homology to the lipase from Pseudomonas glumae.
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Previous purification of a commercial lipolytic preparation from Chromobacterium viscosum using gel filtration chromatography yielded two enzymatically active fractions, named lipases A and B. Characterization of these fractions by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that lipase A consisted of a high molecular weight aggregate of lipase protein with lipopolysaccharides. This complex could be dissociated by treatment with EDTA-Tris buffer containing the non-ionic detergent n-octyl-beta-D-glucopyranoside and subsequent isoelectric focusing in an agarose gel containing the same detergent. Both lipases A and B revealed a major peak corresponding to an isoelectric point of 7.1. SDS-PAGE analysis of lipases A and B after purification by gel filtration or by IEF revealed one major protein band of M(r) of 33 K. Determination of N-terminal amino acid sequences confirmed that both fractions A and B contained the same lipase protein. Furthermore, the N-terminal amino acid sequence of the C. viscosum lipase was identical to the one of Pseudomonas glumae lipase.
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7786903
|
Rate of release and retentivity of prostaglandin E1 in lipid emulsion.
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The rates of release of prostaglandin E1 (PGE1) from lipid particles into aqueous solution were obtained by the dialysis method, for parenteral lipid emulsion (Lipo-PGE1) diluted 10-times with buffered solutions of various pH. The findings, which were the rates of release of PGE1, were used to calculate the amount of PGE1 distributed in lipid particles when Lipo-PGE1, diluted 100-times with various pH levels of the buffered solution, was administered by intravenous drip infusion. More than 90% of PGE1 was retained in the lipid particles and intravenously infused when transfusion fluid pH was less than 5.5 and 2 ml of Lipo-PGE1 and 198 ml of transfusion fluid had been mixed and were administered over 2 h. Results from simulation showed that half of the PGE1 was retained in lipid particles and was infused, if Lipo-PGE1 was diluted 100-times with pH 8 transfusion fluid. Though PGE1 was sparingly soluble in an aqueous solution, these findings demonstrated that a significant amount of PGE1 was retained in lipid particles. Thus, this dosage form is expected to be highly effective for a drug delivery of PGE1 in clinical treatment.
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7786902
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Biliary lipid output by isolated perfused rat livers in response to cholyl-lysylfluorescein.
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The biliary output of bile acids and lipids is tightly coupled. The ability of the natural bile acid glycocholate to trigger biliary lipid secretion was compared with that of the fluorescent bile acid analogue cholyl-lysylfluorescein (cholyl-lys-F). When administered as a 5 min pulse of 2.5 mumol/min to bile acid-depleted rat livers perfused under recycling conditions, glycocholate produced well-defined peaks of phospholipid and cholesterol output, and of bile flow, which were coincident with the peak of bile acid output. Although cholyl-lys-F did trigger biliary lipid secretion, its time course of appearance was delayed and well-defined peaks of output were not observed. However, the increased biliary output of phospholipid and cholesterol was coincident with that of bile acids and, as judged by phospholipid/bile acid and cholesterol/bile acid ratios, cholyl-lys-F was as effective as glycocholate in triggering biliary lipid output. When administered to livers perfused under single pass conditions, perfusate to bile transfer of glycocholate was > 85% at infusion rates of up to 5 mumol/min whereas transfer of cholyl-lys-F showed saturation at infusion rates of > 0.2 mumol/min; the time course of biliary output of both bile acids was similar. Thus, under recycling conditions, cholyl-lys-F not taken up during first pass will be continually represented for transfer to bile, explaining why bile acid and lipid output did not occur as well-defined peaks.
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7786901
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Phospholipid interactions affect substrate hydrolysis by bovine brain phospholipase A1.
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The specificity of substrate hydrolysis by bovine brain phospholipase A1 (PLA1) was examined. In the presence of Mg2+, using pH values of 7 to 9, the purified enzyme deacylated 1-palmitoyl-2-[1-14C]arachidonoyl-phosphatidylethanolamine yielding 2-[1-14C]arachidonoyl-lysophosphatidylethanolamine at a rate of 70 mumol/min per mg. In the absence of Mg2+, however, the reaction rate slowed at pH values above 7.25. In contrast, brain PLA1 slowly (3.8 mumol/min per mg) hydrolyzed 1-palmitoyl-2-[1-14C]arachidonoyl-phosphatidylcholine (PAPC) unless phosphatidylserine (PS) was included. Maximal PAPC hydrolyzing activity required a PAPC/PS molar ratio of 2.5:1, Mg2+, and a pH value of 8.5-9.5. Replacing PS with phosphatidylethanolamine (PE) or phosphatidic acid (PA), but not phosphatidylinositol (PI), produced a similar effect. Moreover, hydrolysis of either arachidonoyl-substituted or dipalmitoyl-substituted PC at pH 7.5 was enhanced by increasing the mol fraction of PE. Brain PLA1 also hydrolyzed 1-stearoyl-[1-14C]arachidonoyl-PI with high velocity, but only if the substrate was dispersed in PE vesicles. In contrast, the velocity of PS, 1-palmitoyl-lyso-PC or diacylglycerol hydrolysis was low and unaffected by PE. In summary, PLA1 hydrolyzed PE with high velocity and specificity, whereas a high rate of PC or PI hydrolysis was observed only if PS, PE, or PA was present. In addition, PLA1 activity was greatly influenced by pH and Mg2+, implying that the substrate conformation is important to the catalytic efficiency of PLA1. Finally, the high rate of PE, PC or PI hydrolysis suggests PLA1 significantly contributes to the turnover of these phospholipids in the brain.
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7786900
|
In vitro determination by 1H-NMR studies that bile with shorter nucleation times contain cholesterol-enriched vesicles.
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Although biliary vesicles are considered to be the primary source of cholesterol found in cholesterol gallstones, difficulties in quantitatively separating the different cholesterol transport modes in bile still remain. Proton nuclear magnetic resonance spectroscopy (1H-NMR) offers an alternative approach. Investigations were carried out on both model biles and human gallbladder bile samples: (i) to follow the effect of increasing sodium glycocholate concentrations on the 1H-NMR spectra of arachidonic acid rich-phospholipid, and cholesterol-lecithin vesicles, (ii) to compare the concentrations of total phospholipids in bile determined enzymatically with those obtained by integration of the phospholipid choline head group resonance peak, and (iii) to examine the relationship between biliary cholesterol nucleation time (NT) and the areas of the biliary lipid 1H-NMR peaks. It was found that the molecular motions of vesicle phospholipid, as determined by 1H-NMR, were restricted by saturation with cholesterol. In bile from patients with cholesterol gallstones, the reduced NMR fluidity of the phospholipid choline-head group indicated that the proportion of cholesterol-phospholipid vesicles containing more than 50% cholesterol, on a molar basis, was increased. The ratios of the N+(CH3)3 and = CH proton resonance peaks showed no overlap between samples with cholesterol gallstones and shorter NT and those with either no gallstones or pigment stones and longer NT. 1H-NMR spectroscopy indicates in a non-invasive manner those biles which are prone to cholesterol crystal formation.
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7786898
|
Effect of maternal ethanol consumption during pregnancy on the phospholipid molecular species composition of fetal guinea-pig brain, liver and plasma.
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The effect of maternal ethanol consumption during pregnancy upon accumulation of docosahexaenoic acid (22:6(n - 3)) into developing brain phospholipids was determined in a guinea-pig model of fetal alcohol syndrome. Feeding adult guinea-pigs 6 g/kg per day ethanol both before and throughout pregnancy was associated with decreased 22:6(n - 3) concentration in both fetal brain phosphatidylcholine (PC) and phosphatidylethanolamine (PE) at 40/68 days gestation and at term. Since adequate assimilation of 22:6(n - 3) into fetal brain is critical for optimal neuronal development, reduced accumulation of 22:6(n - 3) into phospholipids may be one important mechanism for ethanol-induced brain damage. Liver from ethanol-exposed fetuses contained significantly lower concentrations of both PC and PE 22:6(n - 3)-containing molecular species. However, there was no difference in plasma PC polyunsaturated fatty acid content in ethanol-exposed fetuses compared with controls. One possible explanation for impaired 22:6(n - 3) accumulation into ethanol-exposed fetal brain phospholipids may be the result of the action of inappropriate mechanisms which counteract ethanol-induced increased membrane fluidity by reducing the polyunsaturated fatty acid content of brain phospholipids.
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7786899
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7 alpha-Hydroxylation of 25-hydroxycholesterol and 27-hydroxycholesterol in human fibroblasts.
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The metabolism of 27-hydroxycholesterol and 25-hydroxycholesterol was studied in cultures of human diploid fibroblasts. Both steroids underwent 7 alpha-hydroxylation with subsequent oxidation to 7 alpha-hydroxy-3-oxo-delta 4 steroids. A minor fraction of the 27-hydroxysteroids was oxidized to acids. Competition experiments indicated that both hydroxycholesterols were hydroxylated by the same enzyme, different from cholesterol 7 alpha-hydroxylase. 7 alpha,25-Dihydroxycholesterol suppressed the activity of HMG-CoA reductase at least as effectively as 25-hydroxycholesterol whereas 7 alpha,25-dihydroxy-4-cholesten-3-one was a less effective suppressor. The results suggest that cholesterol might be converted to 7 alpha-hydroxylated bile acid precursors in extrahepatic tissues in vivo and that the regulation of the activity of HMG-CoA reductase by oxysterols might be modulated by 7 alpha-hydroxylation and subsequent oxidation by 3 beta-hydroxy-delta 5-C27-steroid dehydrogenase/isomerase.
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7786896
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Release of aldehydes from rat alveolar macrophages exposed in vitro to low concentrations of nitrogen dioxide.
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This study demonstrated that aldehydes are released into the extracellular medium when alveolar macrophages (AM) are exposed to nitrogen dioxide (NO2) at concentrations that impair cell function but do not cause cell death. Butanal, glycolaldehyde, 4-hydroxynonenal, pentanal, pentenal, and hexanal were found. Dinitrophenylhydrazine (DNP) derivitization, thin layer chromatography, high performance liquid chromatography, and gas chromatography-mass spectrometry were used to identify the products. Some of the aldehydes have potential toxicity and may be responsible, in part, for altered AM function observed following NO2 exposure.
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7786897
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Eicosapentaenoic acid causes transient accumulation of lipids in rat myocardium.
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Rats were given eicosapentaenoic acid (EPA) or palmitic acid (PALM) up to 15 days, and control animals were given carboxymethylcellulose. All suspensions which were given by gastric intubation contained tocopherol. Heart triacylglycerols, heart cholesterol and heart phospholipids significantly increased after one day of EPA treatment, but they were normalized within 15 days. Both after 2 and 10 days of treatment with palmitic acid the heart triacylglycerols were significantly greater than control. The heart cholesterol and heart phospholipids were significantly greater than control after 10 days of treatment with palmitic acid. Total carnitine palmitoyltransferase (CPT) activity in heart was significantly greater in rats treated with EPA for 15 days compared to control, but treatment with palmitic acid had no effect. The fatty acyl-CoA oxidase activity was greater in rats treated with EPA for 15 days and palmitic acid for 10 days compared to control. The fractional volume of lipid droplets in myocardial cells was calculated from electronmicrographs and was 0.112 +/- 0.016% after 1 day of EPA treatment compared to 0.035 +/- 0.016% in the control group. After 5 and 15 days the fractional volume was the same as control. The fractional volume of lipid droplets in rats treated with palmitic acid for 10 days was 0.120 +/- 0.023%. Treatment with EPA caused an immediate accumulation of lipids and lipid droplets in the rat heart which after few days normalized in parallel with an increased activity of total CPT in the heart.
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7786895
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Suppression of clofibrate-induction of peroxisomal and microsomal fatty acid-oxidizing enzymes by growth hormone and thyroid hormone in primary cultures of rat hepatocytes.
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Using primary cultures of rat hepatocytes on a matri-gel, effects of peroxisome proliferator and omega-hydroxydodecanoic acid on cellular levels of acyl-CoA oxidase and CYP4A have been studied to determine the hormonal influence in serum-free media. Peroxisomal acyl-CoA oxidation, microsomal CYP4A content and laurate omega-hydroxylation were increased in rat hepatocytes by the addition of 100 microM clofibrate or Wy14,643 for two days. omega-Hydroxydodecanoic acid (100 microM) also increased peroxisomal acyl-CoA oxidation, but had no clear effect on microsomal CYP4A level and laurate omega-hydroxylation. CYP4A-mediated laurate omega-hydroxylation in hepatocytes was suppressed by the addition of pituitary growth hormone (0.05 mU/ml), but was not altered by the addition of triiodothyronine (30 nM). In contrast, clofibrate-mediated induction of acyl-CoA oxidase activity was decreased by the addition of either one of the hormones in hepatocytes. Suppression by those hormones was also observed with omega-hydroxydodecanoic acid-mediated induction of acyl-CoA oxidase activity. These results indicate the possibility that GH and T3 exert the suppressive effects on peroxisomal acyl-CoA oxidation through plural mechanisms with and without the alteration of CYP4A levels in livers.
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7786892
|
Effect of Escherichia coli lipopolysaccharide on surfactant secretion in primary cultures of rat type II pneumocytes.
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The purpose of this study is to evaluate the effect of the Escherichia coli lipopolysaccharide on the secretion of phosphatidylcholine, the principal component of pulmonary surfactant, in primary cultures of rat alveolar type II pneumocytes. Lipopolysaccharide stimulated phosphatidylcholine secretion in a time- and dose-dependent manner. At a concentration of 200 micrograms/ml, lipopolysaccharide stimulated the release of phosphatidylcholine 4-fold over the basal secretory rate, and the concentration producing half the maximal response was 20 micrograms/ml. The stimulatory effect of lipopolysaccharide on phosphatidylcholine secretion was additive to that of the protein kinase C activator TPA, which is a potent stimulator of surfactant secretion. Lipopolysaccharide did not activate protein kinase C, which suggests that stimulation of phosphatidylcholine secretion by the endotoxin was through a mechanism independent of protein kinase C activation.
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7786894
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Purification and characterization of two forms of cytochrome b5 from an arachidonic acid-producing fungus, Mortierella hygrophila.
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Two forms of cytochrome b5 have been purified from the microsomes of an arachidonic acid-producing fungus, Mortierella hygrophila IFO 5941, after detergent solubilization. They have monomeric molecular masses of about 16 kDa and 19 kDa. Their absorption spectra are similar to those of mammalian cytochrome b5s. Their amino acid compositions show some similarity to those of mammalian cytochrome b5s, but the contents of some amino acids (glycine, alanine, aspartic acid + asparagine, glutamic acid + glutamine, arginine, proline, histidine, leucine and lysine) are unique to the cytochrome b5s of M. hygrophila. Some of their internal peptide sequences also show close homology with those of some mammals (approx. 65 to 67%), while some others show no or little homology. The addition of various acyl-CoAs to NADH-reduced microsomes caused an abrupt shiftdown of the steady state reduction level of cytochrome b5. This indicates the increased utilization of electrons for the desaturation process and may suggest that the cytochrome b5s of this fungus actually take part in its microsomal desaturation system for polyunsaturated fatty acid biosynthesis as electron carriers.
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7786893
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Photoaffinity labeling of cottonseed microsomal N-acylphosphatidylethanolamine synthase protein with a substrate analogue, 12-[(4-azidosalicyl)amino]dodecanoic acid.
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N-Acylphosphatidylethanolamine (NAPE), an unusual acylated derivative of phosphatidylethanolamine (PE), is synthesized from free fatty acids and PE in cotton seedlings (Chapman and Moore (1993) Plant Physiol. 102(3), 761-769). Here we use a photoreactive dodecanoic acid analogue, [12-(4-azidosalicy)amino]dodecanoic acid (ASD), and its 125I-labeled derivative to identify a protein subunit which corresponds to this cottonseed NAPE synthase activity. Dodecylmaltoside (DDM)-solubilized microsomal NAPE synthase enzyme was irreversibly and progressively inactivated by adding increasing concentrations of ASD and illuminating with UV254 light. Protection from this photoinactivation was afforded by the natural substrate, palmitic acid. In low light, microsomal NAPE synthase utilized ASD as a substrate to synthesize NAPE; palmitic acid competed for this activity. NAPE synthase activity was measured directly in gel slices following nondenaturing PAGE of DDM-solubilized microsomal membrane proteins. Two-dimensional electrophoresis (nondenaturing PAGE, followed by SDS-PAGE) of photoaffinity-labeled, DDM-solubilized microsomal proteins revealed a 64 kDa polypeptide that was associated with the active NAPE synthase enzyme. Also, a 64 kDa protein was photoaffinity labeled in all NAPE synthase isozyme fractions isolated by preparative isoelectric focusing; photoaffinity labeling of this 64 kDa polypeptide was diminished in the presence of exogenously supplied palmitic acid. Collectively, our results demonstrate that ASD specifically interacts with NAPE synthase in a manner analogous to its fatty acid substrate and indicate that a 64 kDa polypeptide is a component of cottonseed microsomal NAPE synthase. ASD will be a useful molecular probe in future studies aimed at understanding the physiological role of this NAPE synthase enzyme in membranes of plant cells.
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7786891
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Characterization of specific subcellular 15-hydroxyeicosatetraenoic acid (15-HETE) binding sites on rat basophilic leukemia cells.
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15-Hydroxyeicosatetraenoic acid [15-(S)-HETE], a major arachidonic acid metabolite produced from the 15-lipoxygenase pathway, has been characterized as an antiinflammatory cellular mediator since it can inhibit the in vivo and in vitro formation of the proinflammatory leukotrienes via the 5-lipoxygenase pathway in various cells. 15-HETE has been confirmed to inhibit the 5-lipoxygenase in rat basophilic leukemia cell (RBL-1) homogenates with an I50 = 7.7 microM. The I50 of the 12-HETE isomer was 6 microM whereas prostaglandin F2 alpha was ineffective. In order to examine the mechanistic basis underlying the inhibitory action of 15-HETE, association assays of [3H]-15-HETE with RBL-1 subcellular fractions were carried out. The presence of the zwitterionic detergent CHAPS enhanced specific [3H]-15-HETE binding in the membrane fractions three-fold and specific 15-HETE binding was distributed among the nuclear (32%)-, granule (19%)-, plasma membrane (35%)-, and cytosol (14%)-enriched fractions. Studies using combined granule and plasma membrane enriched-, CHAPS treated-fractions showed that [3H]-15-HETE binding was time-dependent, specific and reversible, sensitive to pertussis toxin treatment, and indicated a single class of binding sites with a Kd = 460 +/- 160 nM and Bmax = 5.0 +/- 1.1 nM. Competition experiments showed that the order of 15-HETE or analogs in inhibiting the binding of [3H]-15-HETE was: 15(S)-HETE > or = 12-(S)-HETE = 5-(S)-HETE > 15-(R)-HETE > arachidonic acid. Prostaglandin F2 alpha and lipoxin B4 were ineffective as competitors. The similar profiles of the binding assays and inhibition of the 5-lipoxygenase suggest that 15-HETE binding sites may mediate this inhibitory action of 15-HETE.
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7786890
|
omega-Hydroxylation of docosahexaenoic acid or arachidonic acid in human colonic well differentiated adenocarcinoma homogenate.
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Human colonic well differentiated adenocarcinoma homogenate was incubated with NADPH and docosahexaenoic acid (22:6(n-3)) or arachidonic acid (20:4(n-6)) as a substrate. On a selected ion monitoring chromatogram obtained with reversed phase-high-performance liquid chromatography thermospray mass spectrometry, omega-hydroxydocosahexaenoic acid (omega-HDHE) or omega-hydroxyeicosatetraenoic acid (omega-HETE) from an incubation mixture of the homogenate was detected in significant amount, compared to that from a colonic region remote from the carcinoma. In contrast, epoxydocosapentaenoic acids and the dihydroxy derivatives from 22:6(n-3) or epoxyeicosatrienoic acids and the dihydroxy derivatives from 20:4(n-6) were detected in low amounts, compared to that from a colonic region remote from the carcinoma. The results suggest that highly active NADPH-dependent omega-oxidations of polyunsaturated fatty acids occur in colonic adenocarcinoma homogenate.
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7786889
|
Phospholipid hydrolysis of mildly oxidized LDL reduces their cytotoxicity to cultured endothelial cells. Potential protective role against atherogenesis.
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Oxidized low density lipoproteins (LDL) are cytotoxic to cultured endothelial cells and thereby are potentially involved in endothelial cell injury and atherogenesis. Oxidized phospholipids of oxLDL undergo spontaneous hydrolysis (PL-hydrolysis) by LDL-associated phospholipase A2 (PLA2) activities. The present study aimed to investigate whether hydrolysis of oxidized phospholipids contained in mildly oxLDL could influence their cytotoxicity to cultured endothelial cells. PL-hydrolysis (spontaneous or mediated by exogenous PLA2) of mildly oxLDL elicited a significant reduction of their cytotoxicity to cultured endothelial cells. The reduced cytotoxicity of PL-hydrolysed oxLDL was not due to their reduced uptake by cells, but rather to their reduced content of oxidation products which are liberated by PL-hydrolysis and released (at least the more polar compounds) in the aqueous phase, as shown by ultrafiltration experiments. Oxidation products released in the aqueous phase were not or only slightly cytotoxic to endothelial cells, probably because a selective uptake of non oxidized fatty acids as shown by studies of uptake of oxidized and non oxidized [1-14C]linoleic acid. These data suggest that during PL-hydrolysis of mildly oxLDL, (i) oxidized phospholipids are hydrolysed; (ii) oxidation products liberated from oxLDL particles are released (at least in part) to the aqueous phase; (iii) the cytotoxicity of oxLDL to endothelial cells is reduced, probably because oxidized free fatty acids (released by PL-hydrolysis towards the aqueous phase) are not taken up by the cells. Finally, the possibility of a favourable role of PL-hydrolysis of oxLDL against atherogenesis is discussed.
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7786888
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The role of calcium influx in cellular proliferation induced by interaction of endogenous ganglioside GM1 with the B subunit of cholera toxin.
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The B subunit of cholera toxin, which binds specifically to ganglioside GM1, is mitogenic for quiescent Swiss 3T3 fibroblasts. It was previously shown that the B subunit had no effect on cAMP, protein kinase C or phosphoinositide turnover, but did cause an increase in the influx of calcium from extracellular sources (Spiegel, S. and Panagiotopoulos, C. (1988) Exp. Cell Res. 177, 414-427). In contrast to the action of known growth factors, the B subunit induced significant DNA synthesis after only a 1-3 h treatment. We utilized this unique property to determine whether the increase in calcium influx plays a role in B subunit-induced mitogenicity. Cells were briefly treated with the B subunit in the presence of calcium channel blockers, followed by removal of the blockers and further incubation in B subunit-free medium for the remaining time required to measure DNA synthesis. When 1 mM cobalt was only present during the first 3 h incubation. DNA synthesis induced by either the B subunit or fetal bovine serum was completely abolished. However, both nickel (1 mM) adn the L-type voltage-gated calcium channel inhibitor nicardipin (10 microM) inhibited B subunit-induced cell proliferation without abrogating the response to fetal bovine serum. Using a gel retardation assay, we found that the B subunit markedly stimulated specific DNA-binding activity of the transcription factor, activator protein-1 (AP-1), which functions as a major convergence point coupling early events induced by a variety of mitogens to long term growth responses. Presence of c-Fos protein in the AP-1 complex was demonstrated as a supershift band in the gel mobility assay using c-Fos polyclonal antibody. Cobalt, which markedly inhibited B subunit-induced DNA synthesis, also completely abolished AP-1 DNA-binding activity stimulated by the B subunit. In sharp contrast, cobalt had no effect on DNA-binding activity of AP-1 induced by the tumor promoter, 12-O-tetradecanoylphorbol 13-acetate. Our results suggest that calcium influx is a key element for both DNA-binding activity of AP-1 and cell proliferation induced by binding of the B subunit of cholera toxin to cell surface ganglioside GM1.
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7786884
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The effect of adjunctive light therapy on ameliorating breakthrough depressive symptoms in adolescent-onset bipolar disorder.
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Seven adolescents or young adults (aged 16 to 22 years) who met DSM-III-R criteria for bipolar disorder were treated for persistent depressive symptoms (greater than three weeks) with adjunctive light therapy (10,000 lux given twice per day). Patients were evaluated using the Beck Depression Inventory (BDI) and Symptoms Check List (SCL-58). Three patients showed a marked response of greater than 70% decrease of their baseline score. Two patients had a moderate decrease (40% to 74%) and two patients obtained mild to no response. There were no reported side-effects. Paired t-tests done on pre- and post-BDI scores (pre mean = 21.2 sd +/- 10.0; post mean = 11.1, sd +/- 8.8; paired t = 4.31; p > 0.0051) and pre- and post-SCL-58 scores above baseline of 58 (pre mean = 57.4, sd +/- 24.4; post mean = 28.7, sd +/- 18.6; paired t = 5.50; p > 0.0015) showed significant improvement. These preliminary results indicate that some bipolar adolescents with breakthrough depressive symptoms could benefit from light therapy as an adjunct to their continued thymoleptic treatment.
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7786887
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Optimization of epoxyeicosatrienoic acid syntheses to test their effects on cerebral blood flow in vivo.
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Epoxyeicosatrienoic acids (EETs), normally present in brain and blood, appear to be released from atherosclerotic vessels in large amounts. Once intravascular, EETs can constrict renal arteries in vivo and dilate cerebral and coronary arteries in vitro. Whether EETs in blood will alter cerebral blood flow (CBF) in vivo is unknown. In the present study, the chemical synthesis of four EET regioisomers was optimized, and their identity and structural integrity established by chromatographic and mass spectral methods. The chemically labile EETs were converted to a sodium salt, complexed with albumin, and infused into anesthetized rats via the common carotid. The objective was to test whether sustained, high levels of intravascular EETs alter CBF. The CBF (cortical H2 clearance) was measured before and 30 min after the continuous infusion of 14,15- (n = 5), 11,12- (n = 5), 8,9- (n = 7) and 5,6-EET (unesterified or as the methyl ester, n = 5 for each). Neither the CBF nor the systemic blood pressure was affected by EETs. Because the infusions elevated the plasma concentrations of EETs about 700-fold above normal levels (1.0 nM), it is unlikely that EETs released from atherosclerotic vessels will alter CBF.
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7786885
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Effect of blood sampling on apomorphine-induced penile tumescence in erectile impotence: a case report.
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Apomorphine HCl (Apo) (0.5 mg sc), but not placebo, induced an erectile response (monitored with a mercury strain gauge) lasting 40 min in an impotent hyperprolactinemic patient. Serial blood sampling modified the 40 min erectile response. Prompt detumescence followed by complete or partial restoration of tumescence occurred each time blood was drawn. This observation points to the sensitivity of the Apo-erectile response to experimental procedures subjectively perceived as anxiogenic.
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7786883
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Phosphoinositide system-linked serotonin receptor subtypes and their pharmacological properties and clinical correlates.
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Serotonergic neurotransmission represents a complex mechanism involving pre- and post-synaptic events and distinct 5-HT receptor subtypes. Serotonin (5-HT) receptors have been classified into several categories, and they are termed as 5-HT1, 5-HT2, 5-HT3, 5-HT4, 5-HT5, 5-HT6 and 5-HT7 type receptors. 5-HT1 receptors have been further subdivided into 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E and 5-HT1F. 5-HT2 receptors have been divided into 5-HT2A, 5-HT2B and 5-HT2C receptors. All 5-HT2 receptor subtypes are linked to the multifunctional phosphoinositide (PI) signalling system. 5-HT3 receptors are considered ion-gated receptors and are also linked to the PI signalling system by an unknown mechanism. The 5-HT2A receptor subtype is the most widely studied of the 5-HT receptors in psychiatric disorders (for example, suicide, depression and schizophrenia) as well as in relation to the mechanism of action of antidepressant drugs. The roles of 5-HT2C and 5-HT3 receptors in psychiatric disorders are less clear. These 5-HT receptors also play an important role in alcoholism. It has been shown that 5-HT2A, 5-HT2C and 5-HT3 antagonists cause attenuation of alcohol intake in animals and humans. However, the exact mechanisms are unknown. The recent cloning of the cDNAs for 5-HT2A, 5-HT2C and 5-HT3 receptors provides the opportunity to explore the molecular mechanisms responsible for the alterations in these receptors during illness as well as pharmacotherapy. This review article will focus on the current research into the pharmacological properties, molecular biology, and clinical correlates of 5-HT2A, 5-HT2C and 5-HT3 receptors.
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7786882
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Chronic dopamine antagonism facilitates opiate-induced feeding.
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Chronic interference with dopamine (DA) transmission has been found to facilitate opiate reward and opiate-induced behavioral activation derived from the nucleus accumbens. This study was aimed at determining the extent to which these effects are generalizable to opiate-induced feeding. Rats were tested for their feeding response to morphine following chronic interference with DAergic transmission with the long-acting neuroleptic, flupenthixol decanoate (FLU). It was found that FLU-treated animals showed an enhanced feeding response to morphine following three and four weeks of DA blockade, but not on weeks 1 and 2. Neither morphine treatment in FLU-control animals nor chronic FLU treatment alone produced any such time-dependent facilitation in feeding. The results indicate that the increased sensitivity to the rewarding effects of opiates following chronic DA blockade is generalizable to opiate-induced feeding.
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7786881
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Temperature gradient gel electrophoresis analysis of the beta-NGF gene in schizophrenia.
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Methods for localizing functional polymorphisms in candidate genes are important for the elucidation of pathogenesis in complex diseases such as schizophrenia and manic depression. Temperature gradient gel electrophoresis (TGGE), a variant of denaturing gradient gel electrophoresis (DGGE), can detect single-base mutations in a specified region of double-stranded DNA. This technique has been evaluated for use with polymerase chain reaction (PCR)-generated DNA fragments containing either transitional (A to G) or transversional (T to A) mutations. Single-base mutations of both types are detectable in PCR fragments up to 500 bp long. This method was then used to examine the coding region of the beta-nerve growth factor (NGF) gene for polymorphisms in PCR-generated DNA fragments derived from lymphocyte DNA of subjects with schizophrenia and normal subjects. No single-base mutations in sequence coding for the mature beta-NGF peptide were found in any of the subjects who were examined. If DNA sequence information is available for PCR primer design, TGGE detection of DNA polymorphisms can be used to rapidly determine whether or not a defect in a gene of interest contributes to the pathophysiology of the illness.
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7786880
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Fluoxetine in panic disorder: pharmacologic and tritiated platelet imipramine and paroxetine binding study.
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Serotonergic implication in panic disorder has been demonstrated by the efficacy of serotonin reuptake blockers in treatment. Fluoxetine, a potent 5-HT reuptake blocker, has been suggested to have anti-panic efficacy. This open study examines 30 patients (eight males and 22 females) with an average age of 36.9 years, ranging from 18 to 62, who were treated for eight weeks with fluoxetine (mean dose 20 mg per day). All patients fulfilled DSM-III-R criteria of panic disorder with agoraphobia as determined in a SCID interview schedule. Out of 28 patients who started medication, 64% of the patients completed the clinical trial and 36% of the patients dropped out of treatment because of increased anxiety or a lack of efficacy. Thirty-two percent of the patients had zero panic attacks by week 3. By the end of eight weeks of treatment, 48% of the patients had zero panic attacks. There was a significant reduction in anxiety and phobic avoidance and panic attacks. Tritiated platelet imipramine and paroxetine bindings revealed significantly lower maximal binding for patients with panic disorder in comparison with controls. Paroxetine Bmax showed a trend to increase in the direction of control values by the end of the trial.
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7786879
|
Neuroprotective effect of selenium on iminodipropionitrile-induced toxicity.
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The present investigation was undertaken to study the effect of selenium on experimental dyskinesia in rats. The movement disorders were produced in rats by intraperitoneal administration of iminodipropionitrile (IDPN) in the dose of 100 mg/kg per day for 12 days. Selenious acid was administered daily 30 minutes before IDPN in the doses of 5 mumol/kg, 10 mumol/kg and 20 mumol/kg bodyweight in three different groups of rats. Animals were observed daily for any neurobehavioral changes including circling, backwalking, head weaving and twitching. Immediately after behavioral studies, blood and brain specimens were collected for analysis of thiobarbituric acid reactive substances (TBARS) to measure the extent of free radical production. Our results showed that concurrent use of selenium significantly inhibited IDPN-induced neurobehavioral changes in a dose-dependent manner. Treatment of rats with selenium also reduced the TBARS production in blood and different regions of brain. These findings suggest that selenium attenuates the IDPN-induced neurotoxicity by inhibiting lipid peroxidation.
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7786876
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Dental hygienists in Australia and their employment in orthodontic practice.
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Dental hygienists are the designated dental auxiliary of the future in Australia. This article explains how their duties came into existence and why their duties in orthodontic practice seem limited in some instances. Dental hygienists, a class of operating dental auxiliaries, work in Australian orthodontic practices, but their employment is not widespread. The ratio of hygienists to dentists is reported to be 1:40 in Australia and 1:10 in South Australia (Pash, personal communication).
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7786872
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Quality assurance in orthodontic radiography.
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The implementation of a Quality Assurance (QA) programme in orthodontic radiography is designed to improve the quality of the resultant radiographs and to reduce the number of repeat exposures. This is particularly desirable in orthodontic practice where the majority of patients are young and therefore more at risk from the detrimental effects of X-rays. A programme is described and QA tests are given that may be applied in the surgery. Particular emphasis is placed on QA measures for extraoral radiography, since this is frequently undertaken in the treatment of the orthodontic patient.
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7786870
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Congenital absence of the atlas posterior arch. A case report.
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A report of a healthy young adult woman with non-pathological congenital absence of the lateral and posterior parts of the atlas is presented. This occurred in association with a steep mandibular plane angle and an extremely obtuse gonial angle. Similar facial features are common in females with hypoplastic dorsal arches, and this case illustrates the intimate developmental association between the upper part of the cervical spine and the craniofacial complex.
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7786868
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An evaluation of the views of general dental practitioners who have participated in an extended orthodontic training scheme.
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A questionnaire was sent to 255 dental practitioners who had participated in an extended orthodontic training scheme, incorporating formal teaching and supervised clinical sessions over a period of not less than 24 months. The response of the practitioners was good; 78 per cent of the forms returned were suitable for analysis. Overall, the practitioners responded favourably to the schemes and felt that they had been of benefit to their clinical practice. The majority undertook more orthodontic treatment as a result and on average, fixed appliances were used in half of these treatments.
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7786869
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A sectional approach to the alignment of ectopic maxillary canines.
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A sectional fixed appliance is described for the alignment of ectopic maxillary canines. This system has a number of advantages over conventionally employed mechanics. These include both good aesthetics and optimal tooth alignment.
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7786867
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The Consultant Orthodontists Group survey of hospital waiting lists and treated cases.
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A questionnaire sent to all U.K. hospital orthodontic consultants resulted in an 88 per cent response rate. The average waiting time for initial consultation was 31.6 weeks for routine cases and 3.6 weeks for urgent cases. The average waiting time for out patient treatment was 68.7 weeks for routine cases and 7.5 weeks for urgent cases. Nearly 33 per cent of hospitals used the Dental Health Component of the Index of Orthodontic Treatment need (IOTN) as a guide to placing patients on waiting lists. 'Urgency' and 'Complexity' were used more frequently than indices. Sixty-nine per cent of hospitals exclude some categories of malocclusion from treatment in their departments. A prospective survey reported on 2480 completed treatments over a six week period and there was an average discontinuation rate of 9.2 per cent of all cases finished during the period. Comparison of the completed and discontinued groups revealed few significant treatment-related factors. There was some evidence that the more senior and experienced the operator, the less the rate of discontinuation. A greater rate of discontinuation was seen in removable appliance cases when compared with fixed appliance cases.
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7786865
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The effect of artificial saliva on the frictional forces between orthodontic brackets and archwires.
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The effect of artificial saliva on the static and kinetic frictional forces of stainless steel (Dentaurum) and polycrystalline ceramic (Transcend) brackets in combination with 0.018-inch round and 0.019 x 0.025-inch Edgewise archwire sizes and stainless steel, nickel-titanium and beta-titanium archwire materials, under a constant ligature force were investigated. In all cases, artificial saliva had the effect of increasing the frictional force when compared with the dry state.
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7786866
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Financial consequences of reducing treatment availability in a publicly-funded orthodontic service. A decision analysis problem.
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When a third party is responsible for funding a component of the health service, cost/benefit assessments become important. Such assessments become urgent when the budget is reduced. In this paper decision analysis has been applied to evaluate potential savings by reducing the proportion of children offered free orthodontic treatment through the National Health Service in Denmark. Data for the development of the decision tree was acquired using the Delphi technique. The results suggest that a reduction in the proportion of children offered early treatment might ultimately lead to an increased consumption of resources. Further investigation of the issue is needed before definitive recommendations can be made.
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7786864
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Bond strengths of ceramic brackets using different bonding techniques.
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A series of laboratory investigations was carried out to compare the shear-type bond strengths and site of bond failure of ceramic orthodontic brackets bonded to etched enamel. When light-cured composite resin was used as the luting agent, there was no reduction in bond strength when using 2.5 per cent nitric acid to etch the enamel, compared to 37 per cent phosphoric acid. The use of the two resin modified glass ionomer cements were found to give rise to significantly lower bond strengths than composite resin when used for placing ceramic brackets. Significantly less composite resin remained on the enamel surface following bracket removal in those samples etched with nitric acid.
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7786863
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An investigation into the fluoride release of a variety of orthodontic bonding agents.
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The purpose of this study was to compare the fluoride release from a variety of orthodontic bonding agents. Fluoride release into de-ionized water was measured over a 20-week period. Material based on the fluoride exchange resin was also tested in a saline solution. Fluoride release from a variety of orthodontic bonding agents was compared and the amount of release found to be highly variable. Glass ionomer-based materials showed substantially greater fluoride release when compared with resin-based materials. The presence of anions (Cl-) did not improve the release from fluoride exchange resin. Glass ionomer/resin hybrid material (Vitrabond) released the greatest amount of fluoride.
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7786862
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Effects of cyclic stressing on attachment bond strength using glass ionomer cement and composite resin.
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Bonded orthodontic brackets were subjected to cyclic loading in order to simulate the effect of occlusal forces. The subsequent effect on bond strength was determined. Stainless steel, mesh-based brackets were bonded to extracted teeth with either composite resin or glass ionomer cement. A jig was designed to subject each bracket to a preselected loading level and the 24-hour shear/peel bond strength of both stressed and unstressed brackets was subsequently measured. Cyclic loading brought about a comparative decrease in bond strength when using both types of material. The potential implications of selecting these different types of bonding material for clinical use are discussed.
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7786861
|
Stability of the lower labial segment following orthodontic treatment--a comparison of treatment with Andresen and Begg appliances.
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This retrospective cephalometric study of Class II division 1 malocclusions investigates the effects on the lower labial segment of two forms of orthodontic treatment. Non-extraction Andresen myofunctional therapy and first premolar extraction Begg treatment are compared to the lower incisor changes found in appropriate non-extraction and first premolar extraction control groups, which also presented with Class II division 1 malocclusions. Using four angular and two linear measurements, the lower labial segment was found to procline during Andresen therapy (1-2 degrees, 1-2 mm), and on withdrawal of the appliance it retroclined by about one-half of the in-treatment proclination (0.4-0.8 degrees, 0.1-0.5 mm). During extraction Begg mechanics, the lower incisors were found to retrocline (1.3-1.5 degrees, 0.4-0.9 mm), and they continued to retrocline following removal of the appliance (0.2-3.0 degrees, 0.8-1.1 mm). In general, the variables used to measure lower incisor position demonstrated only very small changes, and were near method error. The reliability of these changes are discussed. It is considered that the axial inclination of the lower incisor in relation to the mandibular plane is the most consistent and therefore still the most useful clinical measurement of lower incisor change available from cephalometric radiographs.
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7786859
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Cephalometric analysis of changes produced by a modified Herbst appliance in the treatment of Class II division 1 malocclusion.
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This study investigated treatment changes produced by the Herbst appliance in a sample of severe Class II division 1 cases, over a period of 8 months. The sample consisted of 16 girls, of whom eight were treated by the Herbst appliance, whilst eight served as controls. All cases were matched with respect to age, sex, skeletofacial morphology, and length of treatment/observation period. Twenty-two skeletal and 19 dental parameters were recorded on pre- and post-treatment cephalograms. The net treatment effect of Herbst therapy was evaluated, taking into account the growth that occurred in the control sample. The study revealed that during 8 months of Herbst therapy there was a significant increase in mandibular length, along with sagittal repositioning. The skeletal changes in the mandible were mainly responsible for overjet and molar relation correction. A slight, favourable forward rotation of the mandible was identified. Dentoalveolar features included flaring of lower incisors and distalization of upper molars. The appliance did not have any retrusive effect on the maxilla. The modified splint design differed from the original and was cemented rather than bonded.
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7786858
|
Perceived length across the physiological blind spot.
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Objects falling across the physiological blind spot appear "complete" despite the absence of photoreceptors. Completion of objects may occur across the blind spot because (1) the blind spot is filled in with the background (the associative explanation); (2) the opposite sides of the blind spot may be contiguously represented in the cortex (i.e. the blind spot is simply sewn up-the retinotopic explanation); or (3) the blind spot may be sewn up, with compensatory expansion occurring around the blind spot (the compensation explanation). These theories would predict no size distortions regardless of object size; constant size distortions regardless of object size; and distortions that depend on the size of the object, respectively. To evaluate these explanations, we measured size distortions at the blind spot. We measured length distortions at the blind spot using a criterion-free two-alternative forced-choice method with feedback. Observers compared the lengths of test bars presented across the blind spot with lengths of reference bars presented at the corresponding location in the fellow eye. Test bar lengths ranged from 7-14 deg. Reference bar lengths were in the range of +/- 3 deg of test bar length. From the observers' responses the perceived length of each bar at the blind spot was estimated. Estimates of the precision of length discrimination at the blind spot were also obtained. Our results were consistent with the associative explanation. In all seven observers, length distortions at the blind spot were smaller than 1 deg (< 20% of the vertical height of the blind spot) for all bar lengths tested. For bars that were presented across the blind spot, the precision with which observers could discriminate length was comparable to that of normal periphery (Weber fraction approximately 20%). Both the veridicality and precision of perceived length are preserved around the blind spot.
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7786856
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The occurrence of dopaminergic interplexiform cells correlates with the presence of cones in the retinae of fish.
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Using light-microscopic immunocytochemistry against tyrosine hydroxylase, we have investigated the morphology of dopaminergic cells in 23 species of fishes representing various systematic classes and subclasses and which live in very different habitats. We have, for the first time, observed teleosts with dopaminergic amacrine cells. Thus, in both bony and cartilaginous fishes, dopaminergic cells are differentiated as interplexiform and amacrine cells. The differentiation of dopaminergic cells into amacrine or interplexiform cells in fishes correlates with the absence or presence of cones. In pure-rod retinae, they occur as amacrine cells, and in mixed rod/cone retinae, they occur as interplexiform cells. We conclude therefore that the differentiation of retinal dopaminergic cells in fish does not depend on the evolutionary or systematic classification of a given species. Rather, it is correlated with the occurrence of rods and/or cones, and thus linked more closely to the habitat. We argue that, in fish, the presence of cones and cone-specific horizontal cells may be responsible for inducing dopaminergic cells to differentiate as interplexiform cells. Possible functions of dopamine in all-rod retinae, which may not require adaptation, may include neuromodulation in the inner plexiform layer for the sensitization of the rod pathway, the shaping of biological rhythms, and the control of eye growth.
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7786857
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Visual latencies in areas V1 and V2 of the macaque monkey.
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Latencies to small flashing spots of light were measured in different layers of areas V1 and V2 in anesthetized and paralyzed macaque monkeys. The shortest latencies were found in layers 4C alpha and 4B of area V1. Latencies in layer 4C beta were on average 20 ms longer than those in 4C alpha and 4B. The shortest latencies in area V2 were observed in the infragranular layers and they did not differ significantly from those found in the infragranular layers in V1. Similarly, latencies in the supragranular layers of V2 were not significantly different from those measured in the supragranular layers of V1. These results show that, in area V1, neurons of the magnocellular pathway are activated on average 20 ms earlier than those of the parvocellular pathway. Our data also suggest that much processing begins simultaneously in areas V1 and V2.
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7786855
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Co-stratification of GABAA receptors with the directionally selective circuitry of the rat retina.
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Direction-selective (DS) ganglion cells of the mammalian retina have their dendrites in the inner plexiform layer (IPL) confined to two narrow strata. The same strata are also occupied by the dendrites of cholinergic amacrine cells which are probably presynaptic to the DS ganglion cells. GABA is known to play a crucial role in creating DS responses. We examined the types of GABAA receptors expressed by the cholinergic amacrine cells and also those expressed by their presynaptic and postsynaptic neurons, by applying immunocytochemical markers to vertical sections of rat retinas. Double-labelling experiments with antibodies against choline acetyltransferase (ChAT) and specific antibodies against different GABAA receptor subunits were performed. Cholinergic amacrine cells seem to express an unusual combination of GABAA receptor subunits consisting of alpha 2-, beta 1-, beta 2/3-, gamma 2-, and delta-subunits. Bipolar cells, which could provide synaptic input to the DS circuitry, were stained with antibodies against the glutamate transporter GLT-1. The axon terminals of these bipolar cells are narrowly stratified in close proximity to the dendritic plexus of displaced cholinergic amacrine cells. The retinal distribution of synaptoporin, a synaptic vesicle associated protein, was studied. Strong reduction of immunolabelling was observed in the two cholinergic strata. The anatomical findings are discussed in the context of models of the DS circuitry of the mammalian retina.
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7786854
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Spectral properties of turtle cones.
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Microelectrodes were used to record from red and green cones of the turtle Pseudemys scripta elegans. The purpose of this study was to determine the action spectra of the red and green cone photopigments, and to look closely for direct interactions between the two cone classes. An isolated retina preparation was employed so that cones could be stimulated from the outer segment side, thereby avoiding the oil droplets that reside in the inner segments of many cones and normally filter incident light. In agreement with some previous electrophysiological studies, we found little evidence for significant direct connections between red and green cones. Exceptions to this rule are noted and discussed. Measurements indicate that this result does not appear to be due to a general loss of cone connectivity in the isolated retina preparation. Action spectra of the cone photopigments differed markedly from action spectra reported for cones in the eyecup preparation. In contrast to cones in the eyecup, cones in the isolated retina showed higher short-wavelength sensitivity and had action spectra that were adequately described by photopigment nomograms. A model of cone optical properties suggests that in the eyecup up to about 40% of the light that reaches a cone outer segment may do so without first passing through an oil droplet.
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7786852
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The influence of input from the lower cortical layers on the orientation tuning of upper layer V1 cells in a primate.
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The receptive fields of cells in the primary visual cortex (area 17 or V1) show clear orientation selectivity, unlike those of the lateral geniculate nucleus (LGN) cells which provide their visual input. The intrinsic circuitry of V1 cells is believed to be partly responsible for this selectivity. We investigated the influence of ascending projections from neurons in the lower layers (5 and 6) of V1 on the orientation selectivity of single neurons in the upper layers (2,3, and 4) by reversibly inactivating ("blocking") lower layer neural activity with iontophoretic application of gamma-aminobutyric acid (GABA) while recording from upper layer cells in the prosimian primate, Galago crassicaudatus. During lower layer blocking, the majority (20/28 = 71.4%) of upper layer neurons exhibited a change in the orientation of their preferred stimulus, a reduction in their orientation tuning, and/or an increase in their response amplitude. Twelve (42.9%) neurons exhibited shifts in their preferred orientation averaging 11 (+/- 4) deg. These neurons were located on average, 272 (+/- 120) microns tangential from the vertical axis of the pipette center. Eleven neurons (39.2%) exhibited an average reduced orientation tuning of 52.5%. Their average location was 230 +/- (115) microns away from the vertical axis of the pipette. Five (17.9%) neurons with average location 145 (+/- 75) microns from the vertical axis exhibited both effects. Two (7.1%) neurons that exhibited significant increases in response amplitude to stimulus angles within 10 deg of the peak excitatory stimulus without changes in orientation selectivity or tuning were located less than 100 microns from the vertical axis. The effects on the orientation tuning of cells were restricted in all cases to within +/- 30 deg of the preferred stimulus orientation. This suggests that layer blocking affects cells with preferred stimulus orientations similar to those of the recorded neurons. Only cells located within 500 microns tangential to the vertical axis of the injection site exhibited these effects. These results suggest that cells within layers 5 and 6 provide organized, orientation-tuned inhibition that sharpens the orientation tuning of cells in the upper cortical layers within the same, or closely neighboring, cell columns.
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7786853
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Behavioral and neural effects of chromatic isoluminance in the primate visual motion system.
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We have previously reported that the responses of individual neurons in macaque visual area MT elicited by movement of contrast-reversing heterochromatic red/green borders are largest when the two hues are "balanced" or isoluminant (Dobkins & Albright, 1994). This "neural" isoluminant point was found to vary somewhat across the sample of neurons. Here, we compare the average neural isoluminant point in area MT to a behavioral measure of isoluminance, obtained using a modification of an oculomotor procedure developed by Chaudhuri and Albright (1992). These behavioral estimates of isoluminance closely parallel the neuronal data obtained from area MT. In accordance with previous evidence (e.g. Lee et al., 1988; Kaiser et al., 1990; Valberg et al., 1992), this correlation suggests that activity within the dorsal/magnocellular stream underlies behavioral expression of chromatic isoluminance.
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7786851
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Calbindin D-28K immunoreactivity of human cone cells varies with retinal position.
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Calbindin D-28K is a calcium-binding protein found in the cone but not rod photoreceptor cells in the retinas of a variety of species. Recent studies of the monkey retina indicated that calbindin D-28K may be expressed preferentially in non-foveal regions of the retina. In the current studies of human retinas, immunohistochemical experiments demonstrated that calbindin D-28K is reduced or absent in the fovea and parafovea, but prevalent in the perifovea and periphery. These findings were supported by the quantification of calbindin D-28K in 1-mm trephine punches obtained from different regions of the human retina. The specificity of the anti-calbindin D-28K antibodies used in these studies was confirmed by Western blot analysis using purified calbindin D-28K. The protein was purified from retinal tissue and its identity confirmed by partial amino-acid sequence analysis. The expression of calbindin D-28K did not correlate with the spectral properties of the cones, rather to their position in the retina. The study of spatially expressed genes, like the one encoding calbindin D-28K, may help explain the patterns of retinal degeneration seen in some human cone-rod dystrophies.
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7786849
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The cat's pupillary light response under urethane anesthesia.
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Pupillary area was measured in urethane-anesthetized cats as a function of retinal illuminance. When appropriate corrections are made for differences in experimental procedures, it was found that the pupillary response of the urethane-anesthetized cat's eyes to light was basically unchanged from that of the alert behaving cat. This preparation may therefore be a very satisfactory one in which to study the pupillary response pathway in a higher mammal.
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7786850
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Receptive-field properties of Q retinal ganglion cells of the cat.
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The goal of this work was to provide a detailed quantitative description of the receptive-field properties of one of the types of rarely encountered retinal ganglion cells of cat; the cell named the Q-cell by Enroth-Cugell et al. (1983). Quantitative comparisons are made between the discharge statistics and between the spatial receptive properties of Q-cells and the most common of cat retinal ganglion cells, the X-cells. The center-surround receptive field of the Q-cell is modeled here quantitatively and the typical Q-cell is described. The temporal properties of the Q-cell receptive field were also investigated and the dynamics of the center mechanism of the Q-cell modeled quantitatively. In addition, the response vs. contrast relationship for a Q-cell at optimal spatial and temporal frequencies is shown, and Q-cells are also demonstrated to have nonlinear spatial summation somewhat like that exhibited by Y-cells, although much higher contrasts are required to reveal this nonlinear behavior. Finally, the relationship between Q-cells and Barlow and Levick's (1969) luminance units was investigated and it was found that most Q-cells could not be luminance units.
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7786847
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Characterization and localization of an aldehyde dehydrogenase to amacrine cells of bovine retina.
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An enzyme of bovine retina that catalyzes oxidation of retinaldehyde to retinoic acid was purified to homogeneity and a monoclonal antibody (mAb H-4) was generated. MAb H-4 recognized a single component (Mr = 55,000) in extracts of bovine retina and other bovine tissues. The antibody showed no cross-reactivity with extracts of rat, monkey, or human retinas. A 2067 bp cDNA was selected from a retina cDNA expression library using mAb H-4. The cDNA hybridized with a similarly sized, moderately abundant mRNA prepared from bovine retina. Nucleotide sequence analysis indicated that the cDNA contained a single open reading frame encoding 501 amino acids that have 88% sequence identity with the amino-acid sequence of human hepatic Class 1 aldehyde dehydrogenase. Amino-acid sequence analysis of purified enzyme demonstrated that the cDNA encodes the isolated enzyme. MAb H-4 specifically labeled the somata and processes of a subset of amacrine cells in bovine retinal sections. Labeled amacrine somata were located on both sides of the inner plexiform layer, and their processes ramified into two laminae within the inner plexiform layer. The inner radial processes of Müller (glial) cells were weakly reactive with mAb H-4. Weak immunostaining of amacrine cells was found in monkey retina with mAb H-4, but no signal was detected in rat or human retina. The results provide further evidence for metabolism and function of retinoids within cells of the inner retina and define a novel class of retinal amacrine cells.
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7786848
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The glial ensheathment of the soma and axon hillock of retinal ganglion cells.
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We have studied the glial investment of ganglion cells of the cat's retina, orienting the sections taken for electron microscopy so that the investment could be traced from the soma along the axon. The soma of each ganglion cell is covered by a close-fitting, continuous sheath formed by Müller cells. The axon hillock and the first part of the initial segment are invested by an extension of the somal sheath, and are thus enclosed in the same glial compartment as the soma. The initial segment extends a few microns past the Müller cell sheath; this last length of the initial segment is contacted by numerous processes of astrocytes, which converge on it in a pattern found also on nodes of the same axons, in the optic nerve. Beyond the initial segment, the intraretinal lengths of the axons are invested by both Müller cells and astrocytes, but the investment is strikingly incomplete. Large areas of axonal membrane have no glial cover, and lie close to other axonal membranes. The sequential arrangement of these distinct forms of glial wrapping of the soma, initial segment, and axon is described here for the first time. It is suggested that this pattern of glial investment controls the flow of current between dendrite and initial segment of the ganglion cell, defines the site of initiation of action spikes, and controls the formation of synapses on the soma and initial segment.
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