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9451942

The use of Baypamun N in crowding associated infectious respiratory disease: efficacy of Baypamun N (freeze dried product) in 4-10 month old horses.

The efficacy of an immunomodulator, Baypamun N, was tested in 4-10-month-old horses which were exposed to stress by weaning, transport mingling with yearlings from different breeders (crowding). Verum (n = 26) and placebo animals (n = 27) received three intramuscular injections of the investigational preparations (days 0, 2, 9) starting at the day mingling in one stable. The incidence of acute respiratory disease was high during the first 4 weeks mingling. Approximately 50% of all horses showed seroconversion due to field infection by EHV1 and EHV4 during the observation period. The clinical scores in the Baypamun N group were significantly reduced by 40.3% (P < pared to the placebo group. The proportion of horses with purulent nasal discharge during the observation period (4 weeks) was also significantly reduced by 58.7% (P < 0.01) in the Baypamun N group. Fifty per cent of the horses injected with Baypamun N showed no purulent nasal discharge and therefore no signs plicated disease of the upper respiratory airways in contrast to only 14.8% in the non-protected placebo group. The challenge conditions studied in this investigation were rather severe because of the permanent exposure of Baypamun N treated individuals to the non-separated and untreated horses (n = 51). This indicates that treatment with Baypamun N is a successful tool to avoid severe clinical consequences of stress in young horses.

9451943

Pathology of Serratia marcescens mastitis in cattle.

Microbiological, cytological, histopathological, and immunohistochemical investigations were carried out on four dairy cows affected by Serratia marcescens mastitis. The animals under study were from a herd of 120 lactating cows bred in the province of Rome. In the above herd, S. marcescens mastitis showed a prevalence of 20.8%. S. marcescens was the only bacterial agent isolated, prior to and after slaughter, from the teat milk, the mammary gland and the supramammary lymph nodes of the four cows under study. Cytologically, the four subjects exhibited high cell counts in their milk, with an average of up to 5,570,000 cells/ml in S.marcescens-infected quarters. Macroscopically, nodular lesions were apparent scattered throughout the mammary parenchyma, with enlargement of the regional lymph nodes. Histologically, a chronic, non-purulent mastitis, characterized by a marked fibrous tissue proliferation and the coexistence of corpora amylacea within the glandular alveoli, was observed in association with chronic hyperplastic lymphadenitis involving the supramammary lymph nodes of the four cows. Immunohistochemically, S. marcescens was demonstrated, by means of monoclonal antibodies, both in the mammary gland and in the supramammary lymph nodes from these four animals.

9451944

The first isolation of Eubacterium suis in Hungary.

Eubacterium suis was isolated from the preputium of seven out of 16 mature boars on two farms and from the urinary bladder of one out of five sows originating from a third herd. The morphological and biochemical characteristics of the isolated strains were identical to that of the reference strain of E. suis ATTC 33144. Three out of four strains isolated from Farm A were successfully subcultured aerobically, and then anaerobically again. E. suis together with Proteus mirabilis was isolated from cystitis of a sow 4 days after artificial insemination. These are the first strains of E. suis isolated in Hungary.

9451945

Relatedness of Staphylococcus aureus strains isolated from milk and human handlers in dairy farms in Trinidad.

The susceptibility of S. aureus strains isolated from milk and human handlers in dairy farms in Trinidad to bacteriophages was determined. Of the 110 strains isolated from bulk milk, 73 (66.4%) were typable either at routine test dilution (RTD) or pared to 108 (72.5%) of 149 strains posite milk sensitive but the difference was not statistically significant (P > or = 0.05; chi 2). Strains of S. aureus from human handlers had significantly (P < or = 0.05; chi 2) lower sensitivity, with only 90 (59.6%) of 151 strains typable. Phages in various groups were predominantly more active on both milk isolates, 54.1% (98 of 181) and human strains, 73.3% (66 of 90). Phage 42D alone lysed 22 (12.2%) but with other phages typed 90 (49.7%) of 181 typable strains from pared to a lytic activity of only 1.1% (1 of 90) alone and 35 (38.9%) with other phages for strains isolated from human handlers. The differences were however not statistically significant (P > or = 0.05; chi 2). Relatedness of S. aureus strains isolated from bulk posite milk and human handlers on each farm was demonstrated in 21 (46.7%) of 45 dairy farms using the phage patterns detected. Similarly, the relatedness of S. aureus strains isolated from the anterior nares and hands of each human milker was detected on 10 (35.7%) of 28 dairy farms studied. It was concluded that S. aureus strains from human milkers contaminated posite and bulk milk on the farms studied while bovine strains of S. aureus were also acquired by humans during milking.

9451946

Severe long-lasting contagious ecthyma infection in a goat's kid.

In this report we describe an unusual orf infection in a goat's kid, which lasted for 6 months. The disease was reproduced in two susceptible goat kids, which pletely recovered within 37 days. Further clinical observations on these kids for 12 months did not reveal any signs of orf disease. The orf virus was isolated and identified from the animals which were involved in the original outbreak, from the kid that showed the long-lasting disease and from the experimentally-infected kids. The situation is discussed.

9451947

[Comparative investigations of practice-oriented methods for the detection of viruses in food with Aujeszky infection in swine as an example].

In order to detect contamination in foodstuffs originating from animals, three different diagnostic methods were tested parison: cultivation in permissive cell cultures, microparticle antigen capture system per FACS (MAS) and polymerase chain reaction (PCR). Assessment implied relevance for health, sensitivity and specificity. Aujeszky infection in swine served as a model. The blood and organs of healthy, but persistently infected as well as specifically diseased animals were examined. In addition, artificially Aujeszky-contaminated milk, black pudding and minced meat were included in parison of methods. Basically, all three methods of detecting contamination in raw foodstuffs originating from animals were useful. The virus detection in cell cultures as well as the efficacy of MAS were inhibited by meat products according to their preparation (e.g., virus protein denaturation). PCR turned out to be the only reliable method to confirm the contamination in foodstuffs. Using PCR, viral contamination in foodstuffs originating from healthy but persistently infected animals could be detected. Each of the three virus detection systems has various advantages and disadvantages. They are listed and discussed in detail. With regard to the relevance of health, virus detection in raw meat via cell culture remains the preferred method. Besides the detection of an individual virus, routine examinations of foodstuffs for unknown zoonotic virus contamination, sets based on permissive cell cultures, primer sets for the PCR as well as sets based on various monoclonal antibodies for MAS have to be developed and made available at the diagnostic laboratories.

9451948

Molecular recognition in fungal mating.

Fungal cells need to recognize that they are genetically different in order to mate. Cells signal to each other by secreting small peptide pheromones which are detected by cell surface receptors. New transcriptional regulators are formed that alter the pattern of gene transcription. Basidiomycete fungi are unusual in having several thousands of different mating types. In these fungi, mating partner recognition demands a remarkable degree of specificity on the part of the proteins and peptides involved.

9451949

Keith R. Porter and the first electron micrograph of a cell.

Keith R. Porter died on 2 May 1997. Although he was especially renowned for the work on cell structure recounted here, his impact on cell biology was not confined to the early electron-microscopic studies of ultrastructure. To many, he was the father of cell biology, who helped establish many of the enduring institutions and ideas in the field. He had great biological intuition and feeling for a wide range of organisms and was greatly concerned with problems of cell shape and movement. He used ultrastructure and simple physiological or biochemical experiments to inter functional activities for cell organelles, including not only the endoplasmic reticulum, which he named, but the sarcoplasmic reticulum and T-tubules of muscle cells, microtubules, cilia, coated vesicles and more. He also pioneered cell studies with the high-voltage electron microscope, which led him to the idea of structural integration in the cell cytoplasm, an idea that is only now being pursued with success.

9451950

A radiation hybrid framework map of bovine chromosome 13.

In this paper we present a 5000-rad radiation hybrid framework map of bovine chromosome 13 (BTA13) containing 13 loci, including five conserved genes and eight polymorphic microsatellites. All framework markers are ordered with odds greater than 1000:1. Furthermore, we present prehensive map of BTA13 integrating 11 genes and 16 microsatellites. The proposed order is in general agreement with the recently published medium-density linkage maps. A model of five blocks of genes with conserved order between human, mouse and cattle is presented.

9451951

Longitudinal differentiation of chromosomes of Asellus aquaticus (Crust. Isop.) by in situ nick translation using restriction enzymes and DNase I.

Asellus aquaticus is an isopod crustacean whose chromosomes cannot be differentiated by G- or R-banding techniques. In this work, we have obtained a longitudinal differentiation of these chromosomes by in situ nick translation using restriction enzymes (HaeIII, DraI and BamHI) and DNase I digestions. The four nucleases, with different efficiencies, have produced similar labelling patterns. Staining with DAPI, Giemsa and chromomycin A3 reveals that the DNA of the nick-translated regions is generally more resistant to extraction from the chromosome. The results obtained on the heteromorphic sex chromosome pair observed in about a quarter of the males of a natural population allow several hypotheses to be advanced on the nature and origin of chromosome dimorphism.

9451952

Mapping chromosomal homology between humans and the black-handed spider monkey by fluorescence in situ hybridization.

We hybridized human chromosome-specific DNA probes to metaphases of the New World monkey Ateles geoffroyi to map the chromosomal homology between these two species. In the haploid Ateles geoffroyi karyotype the total number of signals was 51 for the 22 human autosomal probes used. Compared with Old World monkeys, the number of translocations found in the black-handed spider monkey karyotype was quite striking. The majority of these translocations are apparently Robertsonian and no reciprocal translocations were revealed. Nine autosomal human chromosome probes (11, 13, 14, 17, 18, 19, 20, 21, 22) provided only two signals each per metaphase, but six of these were translocated to subregions of different spider monkey chromosomes. The other 13 autosomal human chromosome paints (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 16) provided fragmented signals. Three human probes (5, 8, 10) provided signals located on two pairs of spider monkey chromosomes. Four human paints (2, 3, 4, 12) provided hybridization signals on three pairs of chromosomes. Probes 6, 7, 15 provided six signals each on two pairs of chromosomes; probe 16 gave eight signals on two pairs of spider monkey chromosomes and probe 1 gave 12 signals on four pairs of chromosomes. The synteny between segments to human 18/8 appears to be an apomorphic ancestral condition for all New World monkeys. A synteny between regions homologous to human 16/10, 5/7 and 2/16 HSA is probably an apomorphic ancestral condition for all Cebidae. The syntenic association 3/15 and 4/1 is an apomorphic condition for the Atelinae.

9451953

Part of the RBM gene cluster is located distally to the DAZ gene cluster in human Yq11.23.

Normal human Y and inverted Y chromosomes were chosen for physical fluorescence in situ hybridization (FISH) mapping of RBM and DAZ probes for the relative positioning of the RBM and DAZ gene clusters in interval 6 of the human Y chromosome. The inversion breakpoint in Yq11.23 turned out to be distal to the DAZ gene cluster, as the entire DAZ signal appears in the short arm of the inv(Y) chromosome. On the contrary, this inversion breakpoint in Yq11.23 divides the RBM signal cluster, leaving a weaker signal on the long arm while bringing the main RBM signal to the short arm of the inv(Y) chromosome. Thus, it can be concluded that, in contrast to previous claims, part of the RBM gene cluster is located distally to the DAZ gene cluster in deletion interval 6 of the human Y chromosome.

9451954

Six bovine cosmid-derived microsatellites mapping different syntenic groups are fluorescence in situ hybridization mapped to six river buffalo chromosomes.

Six bovine cosmid-derived microsatellites (IDVGA53, BTA3/U6; IDVGA61, U13; IDVGA41, BTA12/U27; IDVGA32, BTA15/U19; IDVGA59, BTA26/U26 and IDVGA71, U8), previously assigned to cattle chromosomes, were FISH-mapped to river buffalo chromosomes (BBU) 6q15, 8q34, 13q15, 16q25, 23q22 and 24q13 respectively. Sequential FISH/RBA-banding allowed the precise identification of chromosomes and localization of probe-signals on chromosome bands. These localizations allowed us to assign indirectly, for the first time, six bovine syntenic groups to river buffalo chromosomes, thereby extending its physical map. The localization of IDV-GA71 (bovine U8) to the marker BBU24 adds further information to resolve definitively cattle chromosome ambiguities involving cattle chromosomes 25, 27 and 29.

9451955

FISH mapping of seven cDNA sequences in the pig.

Fluorescence in situ hybridization (FISH) technique was applied to localize seven clones derived from a porcine (SSC) intestinal directionally cloned cDNA library. The size of the clones ranged from 1.1 to 1.3 kb. Three of the clones corresponded to histidyl-tRNA synthetase (HARS), immunoglobulin alpha (IGA) and lysozyme (LYZ) and mapped to SSC2q28-q29, 7q2.6 and 5p11 respectively. The available parative painting data and sequence parisons assisted in a tentative identification of the other three clones as glutathione-S-transferase (GST), glutathione-S-transferase mu (GSTM1) and immunoglobulin lambda gene cluster (IGL@). These clones mapped to SSC14q21, 5q2.4 and 14q22-q23 respectively. The remaining clone representing an EST mapped to 1p24-p25. These localizations contribute to the transcript map in pig and are significant parative markers. Difficulties associated with the mapping of small sequences using FISH are discussed.

9451956

Cytological characterization of four meiotic mutants of Arabidopsis isolated from T-DNA-transformed lines.

A secondary screen of the Feldmann collection of T-DNA transformed Arabidopsis lines identified several meiotic mutants. We used a spreading bined with DAPI staining in a detailed cytogenetic analysis of meiotic chromosome behaviour in four of these mutants, all of which are putatively T-DNA tagged and therefore candidates for molecular and functional analysis of the mutated genes. Two of them are defined as 'synaptic' mutants, showing greatly reduced association of homologous chromosomes at metaphase I: one is asynaptic, showing failure of synapsis during prophase I, whereas the other is desynaptic and is characterized by normal but non-maintained synapsis. Another mutant is defective in meiotic cell cycle control and undergoes a third meiotic division, resembling a second division but without an additional round of chromosome duplication. A further mutant shows meiosis-limited chromosome disruption, resulting in extensive chromosome bined with other defects. All four mutants experience very irregular chromosome distribution during the meiotic divisions, resulting in abnormal numbers and/or sizes of microspores, with resulting reduced fertility.

9451957

Two tandemly repeated telomere-associated sequences in Nicotiana plumbaginifolia.

Two tandemly repeated telomere-associated sequences, NP3R and NP4R, have been isolated from Nicotiana plumbaginifolia. The length of a repeating unit for NP3R and NP4R is 165 and 180 nucleotides respectively. The abundance of NP3R, NP4R and telomeric repeats is, respectively, 8.4 x 10(4), 6 x 10(3) and 1.5 x 10(6) copies per haploid genome of N. plumbaginifolia. Fluorescence in situ hybridization revealed that NP3R is located at the ends and/or in interstitial regions of all 10 chromosomes and NP4R on the terminal regions of three chromosomes in the haploid genome of N. plumbaginifolia. Sequence homology search revealed that not only are NP3R and NP4R homologous to HRS60 and GRS, respectively, two tandem repeats isolated from N. tabacum, but that NP3R and NP4R are also related to each other, suggesting that they originated from mon ancestral sequence. The role of these repeated sequences in chromosome healing is discussed based on the observation that two to three copies of a telomere-similar sequence were present in each repeating unit of NP3R and NP4R.

9451989

In search of biological markers of high-risk carotid artery atherosclerotic plaque: enhanced LDL oxidation.

The oxidation of low density lipoprotein (LDL) is a key event in the development and progression of atherosclerosis because it generates molecular epitopes that are more atherogenic than parent LDL. We found previously that patients with carotid atherosclerosis have a significantly higher titer of autoantibodies against oxidatively modified LDL than normal subjects. The aim of this study is to correlate biological markers of in vivo LDL oxidation with the degree of carotid stenosis and of plaque ulceration (PU) in a series of patients undergoing carotid endoarteriectomy (CEA). Ninety-four consecutive patients (68M and 26F, aged 67.3 +/- 8.2 years) who underwent CEA at our institution between June 1993 and January 1994 were included in the study. The degree of carotid stenosis and the presence and extent of PU were correlated with the level of autoantibodies (IgG) against oxidatively modified LDL (Cu++-oxidized [oxLDL] or malondialdehyde derivatized LDL [MDA-LDL]), that consistently mirrors the occurrence of oxidative modifications in vivo. A statistically significant correlation (r = 0.23, p = 0.039) was found between the degree of carotid stenosis and antiMDA-LDL specific ratio (a parameter that describes the specificity of LDL towards other proteins as target for oxidative modification). A statistically significant correlation was also found between the PU score and antioxLDL IgG (r = 0.32, p = 0.011), antiMDA-LDL IgG (r = 0.25, p = 0.045) and antiMDA-LDL IgG specific ratio (r = 0.38, p = 0.002). None of the classical biochemical parameters (total, LDL and HDL cholesterol and triglycerides) correlated with the above-mentioned plaque characteristics. The results shown, support the use of biological markers of in vivo LDL oxidation (antioxidatively modified LDL autoantibody titers) to evaluate the clinical setting of high-risk carotid atherosclerosis both in screening and in follow-up studies.

9451990

Prophylactic carotid endarterectomy without arteriography in patients without hemispheric symptoms: surgical morbidity and mortality and long-term follow-up.

Between January 1980 and December 1992, 75 prophylactic carotid endarterectomies (CE) were performed on 72 asymptomatic patients presenting high-grade stenosis of the internal carotid artery (ICA). In all patients preoperative assessment consisted of continuous Doppler or duplex scanning. There were 33 women and 39 men with a mean age of 66 +/- 7 years. Surgical exploration confirmed high-grade ICA stenosis in all patients. Mean transstenotic gradient and residual carotid stump pressure determined in 24 patients were 34 +/- 25 mmHg and 51 +/- 20 mmHg, respectively. Combined operative mortality and neurologic morbidity was 1.3% (one death, no permanent neurologic defect). At 5 years, 74% +/- 8% of patients were free of plications, 89% +/- 8% of patients were free of plications affecting the ipsilateral cerebral hemisphere, and actuarial survival was 75% +/- 8%. Most deaths were due to heart-related causes. Multivariate analysis showed that hypertension, age, recurrent stenosis, and contralateral stenosis greater than 50% were risk factors for plications. When only plications were considered, only hypertension was a risk factor. Based on the results of this study, we conclude that prophylactic CE based only on continuous Doppler or duplex scanning is a reliable and safe procedure. Prophylactic CE was effective in avoiding long-term plications due to ipsilateral hemispheric lesions. However, the higher incidence of contralateral plications suggests that close surveillance of contralateral lesions is necessary.

9451991

Screening for carotid and renal artery stenoses in patients with aortoiliac disease.

Patients with severe stenoses of the carotid and renal arteries define a population at high risk but most of them are asymptomatic. Here arises the question of who must be tested and what would be the actual utility of a screening program in the general or selected populations. The aim of this study was to assess the efficacy of a duplex-based screening for carotid and renal arteries stenoses, in a subset of patients with aortoiliac arterial disease, in terms of: (1) prevalence of occlusive disease of the carotid and renal arteries detected and surgical procedures generated; (2) analysis of clinical variables that could be useful to increase the suspicion index for the disease; and (3) predictive values of duplex scanning adjusted for the observed prevalence. One hundred sixty eight consecutive patients selected for elective aortoiliac surgery were included. Carotid duplex scanning, renal duplex scanning and/or aortorenal angiography, and recording of clinical predictive variables were obtained in all the patients. The statistical analysis included prevalence rates, multivariate analysis, and predictive values of carotid and renal duplex scanning adjusted for the observed prevalence. Greater than 50% asymptomatic stenosis in at least one of the internal carotid arteries (CAS > 50%) was detected in 47 (28%) patients [95% confidence interval (CI): 21.2%-34.8%]; 67 (39.9%) patients showed greater than 60% stenosis in one or both renal arteries (RAS > 60%) (95% CI: 32.5%-47.3%). Based on current surgical indications, carotid endarterectomy was performed in 24 (14.3%) patients and a bypass to the renal artery in 30 (17.8%) patients. Logistic regression analysis accepted the following variables, in this order: carotid bruit, age, and ankle/brachial index for predicting carotid artery stenosis; and hypertension and CAS for predicting renal artery stenosis. Based on previous validation studies of duplex scanning accuracy, estimated positive predictive values for significant stenosis of the carotid and renal arteries showed a range of 80.5%-89.1% and 82.3%-89.7%, respectively. Routine screening of the carotid and renal arteries may be justified in those patients with aortoiliac aneurysmal and occlusive disease, provided there is a high prevalence of clinically significant lesions and sufficient predictive values of duplex scanning are obtained.

9451992

Prophylactic carotid endarterectomy in patients with high-grade carotid stenosis undergoing coronary bypass: does it decrease the incidence of perioperative stroke?

The etiology of perioperative stroke in patients undergoing isolated coronary artery bypass grafting (CABG) is multifactorial. One significant cause is thought to be high-grade internal carotid artery stenosis. Between April 1992 and June 1995, 1686 patients undergoing isolated CABG underwent preoperative carotid duplex scanning. This represented 77% of patients who underwent CABG during that time period (2188 patients). Sixty-eight patients (4.0%) had 80%-99% stenosis of at least one carotid artery. Fifteen patients underwent CABG without carotid intervention (Group I) and 53 patients underwent either carotid endarterectomy prior to CABG or simultaneous with CABG (Group II). Age, sex, history of prior neurologic events, ejection fraction, number of distal bypasses performed, total pump time, and aortic cross clamp times were similar between the two groups. Three patients in Group I developed a permanent postoperative neurologic deficit (20%) and one patient developed a transient deficit. The defect was focal and ipsilateral to high-grade stenosis in three patients and global in one. No patient in Group II developed either a transient or permanent neurologic deficit. There was one death in Group I in the patient who developed a global neurologic deficit and one death in Group II 2 weeks after CABG in a patient who had undergone prophylactic preCABG-carotid endarterectomy. Statistical analysis (Fisher's exact test, 2-tail) demonstrated a significant decrease both in total neurologic events (p = 0.001) and permanent neurologic defects (p = 0.005) in those patient undergoing prophylactic CE (Group II). Patients with 80%-99% carotid stenosis undergoing CEA prior to or in conjunction with isolated CABG have a decreased incidence of neurologic events postoperatively.

9451993

Surgical treatment of patients with symptomatic vertebrobasilar insufficiency.

We report our experience with surgical management of symptomatic vertebrobasilar insufficiency (VBI). Forty revascularizations were carried out in 39 patients over 90 months. Dizziness (52%) and syncope/presyncope (32%) were the mon symptoms. Arteriography was performed in all patients, with subclavian steal seen in 55% of patients. Procedures performed included 22 cases of carotid-subclavian bypass or transposition (55%), seven direct vertebral reconstructions (17.5%), four great vessel reconstructions (10%), four isolated carotid endarterectomies (10%), and three axilloaxillary bypasses (7.5%). One patient died, and bined morbidity and mortality rate was 15%. Outpatient follow-up was available on 37 of the 38 patients discharged alive. At a mean follow-up of 16.4 months, 34 patients had no plaints. Three of four patients treated with CEA alone had persistent plaints. We conclude that a variety of anatomic lesions can result in VBI symptoms, with subclavian steal being the mon. Procedures which directly correct the anatomic abnormality result in sustained symptom resolution with plication rates.

9451994

Role of plasma and extracellular matrix proteins in the physiopathology of foreign body infections.

Foreign body implants are highly susceptible to microorganism infection. The infectious agents may be of low pathogenicity (such as S. epidermidis) or involve more virulent strains (such as S. aureus). mon denominator for the three main elements that play a role in the physiopathology of such infections (bacteria, neutrophils, and different biomaterials) are host proteins deposited over the surface of the devices immediately after their implantation. These proteins modulate that host cells response but can also promote Staphylococcus adhesion to the biomaterial. Neutrophils and other cells such as fibroblasts adhere to several extracellular matrix proteins such as fibronectin, fibrinogen, collagen, vitronectin, via specific cell surface receptor. The evolution of the technology and the increasing numbers of long-term artificial implants require a better understanding of fundamental mechanisms of foreign body infections to reduce their incidence and optimize their treatment.

9451995

Nicotine-stimulated elastase activity release by neutrophils in patients with abdominal aortic aneurysms.

Elevated elastase activity in patients with chronic obstructive pulmonary disease (COPD) is attributable to the direct effect of nicotine. COPD is also known to be an independent predictor of abdominal aortic aneurysm (AAA) growth and rupture. The purpose of this study is to determine the effect of nicotine on elastase activity release from neutrophils of AAA patients. Human neutrophils were extracted from the blood of subjects in the following six groups, n = 10 in each group: smoking AAA (SAAA), nonsmoking AAA (NSAAA), smoking aortic occlusive disease (SAOD), nonsmoking aortic occlusive disease (NSAOD), smoking controls (SC), and nonsmoking controls (NSC). After incubation with varying nicotine concentrations (0-1000 microg/ml), the released elastase activity was determined. There is generally an elevation in elastase activity release by neutrophils of pared to nonsmokers. Nicotine exposure stimulated increased elastase activity release in AOD and AAA, and the increase was especially pronounced in the SAAA and SAOD groups. The elevation was greatest in the SAAA group while the release was lowest in the NSAOD group. There is a direct correlation between elastase activity release and nicotine concentration. The data suggest that COPD and AAA development, which may occur by similar initial mechanisms may also be aggravated by nicotine-induced neutrophil elastase activity release. In addition, the results indicate that nicotine is playing an active role in the development of vascular disease by inducing neutrophils to release elastase activity.

9451996

Apparent blood stream origin of endothelial and smooth muscle cells in the neointima of long, impervious carotid-femoral grafts in the dog.

The purpose of this study was to determine whether endothelial and smooth muscle cells originating from the blood stream contribute to the endothelialization of impervious, small-caliber, long Dacron grafts used as extraanatomical bypasses in dogs. We implanted silicone-rubber-coated, permanently impervious grafts 64 to 77 cm long and 6 mm in diameter, made of externally supported knitted Dacron as unilateral carotid-femoral bypasses with distal femoral arteriovenous fistulae in 10 dogs for 3 months; sides were alternated between cases. Subjects received 162 mg/day of aspirin, and its effectiveness on platelet aggregation (PA) was evaluated and expressed as a PA score. Graft healing was studied by stereomicroscopy with silver nitrate staining, by light microscopy with hematoxylin-eosin and immunocytochemical staining for endothelial and smooth muscle cells, and by scanning and transmission electron microscopy. Five grafts were patent for 3 months and could be included in the healing study; the five occluded grafts thrombosed within 14 days. Although there was no transinterstitial tissue ingrowth from perigraft tissues into the impervious Dacron grafts, scattered islands of endothelial cells were conclusively demonstrated on graft flow surfaces 3 months after implantation. Average endothelial-like cell coverage of the flow surfaces was 15.6% +/- 3.8%, and alpha-actin-positive smooth muscle cells and microvessels were found beneath some of the endothelial islands. These findings suggest that blood stream-derived endothelial and smooth muscle cells play a role in the healing of the inner wall of Dacron grafts in the dog.

9451997

Mechanics of spatulated end-to-end artery-to-vein anastomoses.

It previously has been shown that in straight end-to-end artery-to-vein anastomoses, maximum dimensions are obtained with an interrupted suture line. Nearly equivalent dimensions are obtained with a pliant polybutester suture (Novafil), and the smallest dimensions are obtained with a continuous pliant polypropylene suture (Surgilene). The present study was undertaken to examine these suture techniques in a spatulated or beveled anastomosis in living dogs. Anastomoses were constructed using continuous 6-0 polypropylene (Surgilene), continuous 6-0 polybutester (Novafil), or interrupted 6-0 polypropylene or polybutester. Thirty minutes after construction, the artery, vein, and beveled anastomoses were excised, restored to in situ length and pressurized with the lumen filled with a dilute suspension of barium sulfate. High resolution radiographs were obtained at 25 mmHg pressure increments up to 200 mmHg. Dimensions pliance were determined from the radiographic images. Results showed that, unlike straight artery-to-vein anastomoses, there were no differences in the dimensions pliance of spatulated anastomoses with continuous Surgilene, continuous Novafil, or interrupted suture techniques. Therefore a continuous suture technique is acceptable when constructing spatulated artery-to-vein anastomoses in patients.

9451998

Limb salvage surgery in spinal cord injury patients.

Advances in the care and rehabilitation of patients with spinal cord injuries (SCI) have resulted in extended survival following injury. Increasingly, we are faced with difficult chronic lower extremity plications in SCI patients. Recognizing limitations associated with amputation in these nonambulatory patients, we report the preliminary results of a program of selective limb salvage via arterial reconstructive surgery. Retrospective chart review was performed on the records of the Veterans Affairs Palo Alto Health Care System SCI unit. Since 1989, 15 revascularization procedures were identified in 10 SCI patients. All patients suffered from ischemic ulceration and/or gangrene. Procedures performed included femorotibial bypass (8), aortofemoral bypass (4), femoro-femoral bypass (2), and axillobifemoral bypass (AXF) (1). All patients were men. The mean age was 56 (range 43-73). Follow-up was available on 10 procedures performed in seven patients since 1992. Mean follow-up was 17 months. One patient died 3 months following distal bypass. The AXF occluded within 1 month. One distal bypass occluded in the immediate postoperative period and could not be salvaged. All other grafts remain patent, and all wounds have healed following successful bypass. One patient developed pressure ulceration following AXF grafting due to postoperative upper extremity limitations. No plications were encountered. Standard arterial reconstructive procedures can be performed safely and successfully in SCI patients, despite diminished limb blood flow due to inactivity, and atrophic arteries, muscle, and fascia. Axillobifemoral bypass grafting may not be suitable in SCI due to requirements for upper extremity-based mobility. Confirmation of benefit of limb salvage versus amputation parison between patients eligible for either procedure.

9451999

Epidural versus general anesthesia: does anesthetic management influence early infrainguinal graft thrombosis?

A few contemporary reports have suggested that the use of epidural anesthesia may favorably influence early graft patency in patients undergoing infrainguinal revascularization. In order to test this hypothesis, we have retrospectively reviewed our experience with 303 primary femoropopliteal-tibial bypass procedures in 294 patients from January 1989 through June 1994. A total of 145 of these operations were done under epidural anesthesia (EA) and 158 under general anesthesia (GA); the demographic profiles for the patients in both of these groups were nearly identical. Thirteen patients (4.2%) died during the perioperative period (EA 3.4%, GA 5.0%; p = 0.48). Early graft thrombosis occurred in 35 patients (12%) during the same hospital admission (EA 14%, GA 9.4%; p = 0.28). There were no significant differences in the graft thrombosis rates for EA and GA with respect to surgical indications (claudication versus limb salvage), graft materials (vein versus synthetic), or the extent of revascularization (popliteal versus crural). Most graft failures appeared to be related to such conventional factors as disadvantaged outflow vessels and/or specific plications. Therefore, we conclude that the choice between EA and GA should continue to be made selectively on the basis of traditional anesthetic considerations.

9452000

Foot TcPO2 response to lumbar sympathectomy in patients with focal ischemic necrosis.

We prospectively evaluated all patients with superficial foot necrosis of 1-3 cm and transcutaneous oxygen tension (TcPO2) values of <30 mmHg who received a sympathectomy as the primary treatment of their vascular occlusive disease. Preoperatively, and every 2-3 days in the postoperative period, measurement of TcPO2 of the forefoot was performed. Clinical success was defined as healing of the necrosis or healing of a toe amputation and avoidance of a major below-knee/above-knee amputation for 1 year. Ten patients were available for long-term evaluation. During the first 4-5 days, all patients increased their foot TcPO2 and the mean increase (23 mmHg) was significant (p = 0.04). Clinical improvement was marked by an average increase of 29 mmHg by postoperative day 10. In contrast, patients with clinical failure had only an average increase of 5 mmHg in TcPO2 by the same postoperative interval. Preoperative increase in TcPO2 by at least 20 mmHg in response to dependency predicted a favorable response to sympathectomy. In addition, sustained postoperative increases in tissue oxygen levels by postoperative day 10 also favored wound healing.

9452001

Idiopathic renal arteriovenous fistula: treatment with embolization.

We report a case of idiopathic renal arteriovenous fistula revealed by microscopic hematuria in a 36-year-old man with no predisposing history. Treatment with selective embolization plete resolution with no parenchymal damage.

9452002

Aneurysm of a common celiomesenteric trunk.

Aneurysm of the celiac and/or superior mesenteric arteries are mon, accounting for 10% of visceral artery aneurysms. Aneurysms involving mon celiomesenteric trunk are extremely rare. Up to now only two cases have been reported. In this report we describe a saccular aneurysm originating from the bifurcation of mon celiomesenteric trunk. Treatment consisted of resection followed by suture of the aneurysmal neck. This anatomic variation of the visceral arteries probably resulted from a defect in embryonic development suggesting that the aneurysm was congenital in origin. Other etiologies of aneurysms in this location are atherosclerosis, infection, inflammation, and arterial dystrophy. These lesions are almost always surgical indications plete angiographic study of the visceral vasculature.

9452003

Surgical drainage for idiopathic suppurative pylephlebitis.

Idiopathic suppurative pylephlebitis is quite rare and only a few cases have been reported. Conservative systemic administration of antibiotics and urokinase is reported to be effective. In this report, surgical drainage was performed on an 18-year-old man plained of fever and abdominal pain. He had no past history of abdominal inflammatory disease or abdominal surgery. Ultrasonography puted tomography showed wide spread thrombosis of the portal vein. Laparotomy was performed and the occluded superior mesenteric vein was incised. Massive pus was removed. Thereafter, a drain was placed at the opened mesenteric vein. Drainage resulted in a dramatic decrease in fever. Postoperative radiographic studies of the colon, the small intestine, and other organs did not show any abnormalities. Emergency surgical drainage was performed successfully, instead of systemic administration of antibiotics and urokinase. Surgical drainage may be useful for wide spread pylephlebitis and pylethrombosis.

9452004

Diagnosis of aortocaval fistula by computed tomography.

A case of an aortocaval fistula documented by puted tomography is reported. In the presence of a large abdominal aortic aneurysm, puted tomography (CT) triad findings of: (1) vena caval effacement, (2) loss of the fat plane between the aorta and vena cava, and (3) rapid flow of contrast from the aorta into a dilated inferior vena cava is characteristic of an aortocaval fistula.

9452005

Cellular and molecular basis of cerebral dysgenesis.

Maldevelopment of the cerebral cortex, cortical dysgenesis (CD), may be associated with epilepsy, mental retardation (MR), and focal or widespread neurologic deficits. The histologic hallmark of CD is disrupted cytoarchitecture, including disorganized lamination, malpositioned neurons with respect to their normal radial orientation, abnormal dendritic arborization, and heterotopic neurons within the white matter. Seizures in these patients are particularly difficult to control with conventional anti-epileptic drugs (AEDs) and may require epilepsy surgery to remove these abnormal foci. Focal CD has been reported in up to 30% of epilepsy surgery specimens and are believed to provide the central pathologic substrate responsible for seizures in these patients. How and why CD results in epileptiform activity is unknown. Advances in understanding the pathogenesis of some types of CD have occurred recently with the cloning genes responsible for a few types of X-linked and autosomal CD. This review will outline the major subtypes of CD, the pathologic findings, and the molecular etiologies for a variety of CD. We will also address recent experimental advances in studying the pathogenesis of CD.

9452006

Regulation of murine myelin proteolipid protein gene expression.

To identify putative sequences that direct cell type-specific expression and/or enhance proteolipid protein (PLP) gene expression, glial or nonglial cells were transfected with various PLP-luciferase constructs that collectively span the entire mouse PLP-specific DNA present in a transgene known to direct cell type specificity in transgenic mice. These constructs were transfected into murine oligodendrocyte cell lines that transcribe the PLP gene and, hence, should contain the requisite trans-acting factors necessary for PLP gene expression. Mouse NIH/3T3 fibroblasts were used as a nonglial model. We have finely mapped the PLP promoter region for transcriptional regulatory elements and demonstrate both positive and negative elements, none of which appear to extinguish expression in nonglial cells. The 5'-flanking PLP DNA tested did not enhance the basal herpes simplex-1 virus thymidine kinase (TK) promoter, nor did PLP sequences present in the distal half of intron 1. The 5' portion of intron 1 did enhance TK promoter activity, suggesting that this region of the gene may contain enhancer elements that modulate PLP gene expression; however, the enhancement did not appear to be cell type-specific. Intriguingly, a 541 bp region of the intron that significantly enhanced TK promoter activity contains multiple JC virus repeated elements and other elements known to be important in restricting the virus to oligodendrocytes. These results suggest that intron 1 sequences may modulate expression of the PLP gene.

9452007

Structural characterization of myelin-associated glycoprotein gene core promoter.

Myelin-associated glycoprotein (MAG) is emerging as an important molecule involved in the plasticity and regeneration of the central nervous system. In this study, the structure of MAG gene promoter was characterized in cultured rat oligodendrocyte lineage cells. Heterogeneous transcription initiation with five major and eight minor start sites scattered within 72 bp was shown by primer extension analysis. This TATA-less core promoter contains no prominent initiator (Inr) elements associated with the transcription initiation sites, and hence, appears to utilize novel positioning mechanisms. Genomic footprinting analysis revealed several putative protein-binding regions overlapping the initiation sites and containing a multitude of CG-rich sequences. However, no conspicuous alterations in the protein-binding pattern were evident between O2A progenitors in which the gene is inactive, and mature oligodendrocytes with fully upregulated gene. The core promoter DNA features a differentiation-dependent demethylation as shown by genomic sequencing analysis. Three of eight cytosines are totally demethylated in oligodendrocyte chromosomes, indicating that these unmodified bases may be critical for full activation of the promoter. The core promoter is located within an internucleosomal linker, and the upstream regulatory region appears to be organized into an array of nucleosomes with hypersensitive linkers.

9452008

Cyclooxygenase 2 RNA message abundance, stability, and hypervariability in sporadic Alzheimer neocortex.

Long-term treatment by nonsteroidal anti-inflammatory drugs has been shown to decrease the incidence of Alzheimer's disease (AD). Both platelet-activating factor and interleukin-1beta, potent mediators of the inflammatory and immune response, strongly induce transcription of the cyclooxygenase-2 (COX-2) gene in brain cells. Using Northern and RT-PCR analysis, we have determined in 15 control and 10 sporadic AD human neocortical samples (age range, 60-82 yr; postmortem interval [PMI] range, 0.7-16.0 hr) the levels of COX-2 RNA in relation to the constitutively expressed COX-1 and beta-actin RNA message levels. Our results indicate that in short PMI brain, COX-1 and COX-2 transcripts are relatively low abundance RNA messages, ranging from a mean of 6.8% of the beta-actin signal in controls to 8.5% of the beta-actin signal in AD-affected brain. A large variation in the signal intensity for COX-2 RNA was noted in both control and AD; although there was a trend for higher COX-2 RNA message abundance in AD neocortex to +11.5% of that of controls, it did not reach statistical significance (ANOVA = 0.45). Several human tissues, including heart, skeletal muscle, lung, kidney, and spinal cord, displayed 4.6- and 2.8-kb COX-2 RNA message isoforms; however, the 4.6-kb COX-2 RNA predominated in the hippocampus and association neocortex. COX-2 RNA message was found to be degraded at similar rates in both control and AD tissues, and a strong positive correlation between the PMI and the intensity of the COX-2 RNA signal was noted (ANOVA = 0.006). Linear regression analysis indicated that the 4.6-kb COX-2 RNA is an unstable short-lived RNA species with a half-life of not more than 3.5 hr, a feature characteristic of immediate early gene transcripts. Individual hypervariability in COX-2 RNA message abundance may reflect various degrees of expression of AD-related inflammatory processes.

9452009

HIV-gp120 affects the functional activity of oligodendrocytes and their susceptibility to complement.

The aim of this study was to assess whether the HIV protein gp120 can induce direct or/and indirect damage to oligodendrocytes (OL). Using highly purified cultures of rat OL, we report that gp120 binds to OL and induces functional alterations in these cells. Indeed, the percentage of cells expressing myelin basic protein (MBP) and the levels of all four MBP isoforms were substantially reduced after a 3-day treatment with 10 nM gp120. As gp120 depressed the ability of OL to reduce the tetrazolium salt MTT (a sign of mitochondrial impairment), the alteration of MBP production may be a consequence of decreased metabolic activity. The above effects were panied by a small increase in the number of apoptotic nuclei (from 4.3% in controls to 17.6% in cells treated for 3 days with gp120). plement can lyse OL and gp120 is known to plement, we also studied the interaction between these two factors using OL cultures. The viral protein potentiated (by about 25%) the lytic effect plement, when administered to the cultures 5 hr plement, and depressed it (by about 30-40%), when added 5 hr plement. Heat denaturation and anti-gp120 antibodies prevented the direct effect of gp120 on OL, but did not influence the interactions between gp120 plement. Some gp120 non glycosylated peptides (V3 loop, 254-274 and 415-435 peptides) mimicked the ability of gp120 to antagonize the lytic effect plement, but not that of plement lytic activity. In conclusion, our study indicates that gp120 can alter OL functional activity directly and can interfere with OL susceptibility plement mediated lysis.

9452010

Expression and imprinting of the insulin-like growth factor II gene in neonatal mouse cerebellum.

Insulin-like growth factor II (IGF-II) plays significant roles in the growth and development of mammals through the regulation of mitogenesis and cell survival. Previously, IGF-II mRNA transcripts within the CNS were detected in the choroid plexus and leptomeninges (DeChiara et al., 1991). The objective of this study was to determine the expression pattern of IGF-II mRNA in different cell types of the cerebellum during development. We report here that the IGF-II gene is transcribed in granule and glial cells within the cerebellar parenchyma at various times during the early postnatal period in mice. IGF-II gene expression is further regulated by parent-specific imprinting such that only the paternal IGF-II allele is expressed in granule cells. In contrast, choroid plexus and leptomeninges express IGF-II mRNAs biallelically, indicating that cell type-specific regulation of genomic imprinting occurs within the mammalian CNS.

9452011

Developmental changes of potassium currents of embryonic leech ganglion cells in primary culture.

The expression of calcium-activated potassium currents (IK(Ca)), delayed outward rectifier potassium currents (IK(slow)), and transient outward currents (IA) was studied during the development of the nervous system of the leech using the whole-cell patch-clamp recording technique. Dissociated cells were isolated from leech embryos between stage E7 and E16 and maintained in primary culture. K+ currents were recorded at E7, when only few anterior ganglia had formed beneath the primordial mouth. IK(slow) was present in all cells tested, while IK(Ca) was expressed in only 67% of the cells studied. Even as early as E7, different types of IK(Ca) have been found. Neither frequency of occurrence nor the charge density of IK(Ca) showed significant changes between E7 and E16. The density of IK(slow), however, increased by a factor of two between E7 and E8, which resulted in a significant increase in the total K+ current of these cells. This rise in potassium outward current developed in parallel with the appearance of Na+ and Ca2+ inward currents (Schirrmacher and Deitmer: J Exp Biol 155:435-453, 1991) during early development, shaping the electrical excitability in embryonic leech neurones. I(A) could be separated by its voltage-dependence and pharmacological properties. The current was detected at stage E9, when all 32 ganglia are formed in the embryo. The frequency of occurrence of I(A) increased from 16% at E9 to 70% at E15. The channel density, steady state inactivation, and kinetics showed no significant changes during development.

9452012

Rapid impact of beta-amyloid on paxillin in a neural cell line.

Beta-amyloid1-42 (Abeta) is a naturally occuring peptide whose accumulation in the brain is putatively coupled to Alzheimer's disease pathogenesis. Deleterious effects of Abeta on neurons have been linked to the inappropriate activation of signaling pathways within the cell (reviewed in Yankner, 1996), including tyrosine phosphorylation of focal adhesion kinase (FAK) (Zhang et al., 1994, 1996a,b). Here we have investigated the effects of Abeta on paxillin in a neural cell line. Paxillin, a substrate for FAK, is thought to act as a signal "integrator," functioning to link other proteins into multi-molecular plexes (reviewed in Turner, 1994). Treatment of the rat central nervous system B103 cell line with aggregates of Abeta was found to induce the tyrosine phosphorylation of paxillin within 30 min, nearly 24 hr prior to significant cell death. Particularly striking was a subsequent "mobilization" of paxillin to the cytoskeleton in Abeta-treated cells. The amount of paxillin associated with the cytoskeleton in Abeta-treated cells was increased 10-fold over controls. The Abeta-induced paxillin accumulation could be visualized immunocytochemically, with an increase in number and size of paxillin-labeled focal contacts upon treatment with Abeta. This effect was specific, in that vinculin, another focal contact protein, was unaffected by Abeta. Disruption of f-actin, which inhibits both Abeta-induced neurotoxicity (Furukawa and Mattson, 1995) and focal contact signaling in B103 cells (Zhang et al., 1996b) was found to block the cytoskeletal paxillin accumulation. The rapid tyrosine phosphorylation and cytoskeletal mobilization of paxillin links Abeta to the activation of focal contact signaling events that may influence neuronal cytoskeletal architecture, gene expression, synaptic plasticity and cell viability.

9452013

Tumor necrosis factor enhancement of transient outward potassium currents in cultured rat cortical neurons.

The effect of binant human tumor necrosis factor-alpha (TNF) on voltage-gated membrane currents of cultured neurons derived from embryonic rat cerebral cortex was studied using the whole-cell patch-clamp technique. Treatment of neurons with TNF resulted in an increase in outward potassium current density, dependent upon the concentration of TNF and the incubation time, without affecting other membrane currents such as barium and N-methyl-D-aspartate (NMDA). Long exposures (12-48 hr) to TNF (10-100 ng/ml) increased transient outward potassium current (A-current) density without affecting the parameters of activation and inactivation of the current. Prolonged exposures to TNF diminished its increasing effect on the A-current. Since the increase of A-current density induced by TNF is inhibited by both the anti-TNF receptor antibody and cycloheximide treatment, the effect of TNF might be mediated through receptors and by de novo synthesis of the channel protein itself and/or modulating proteins associated with the channel activities. Results indicate that phosphatidylcholine-specific phospholipase C and protein kinase C, but not ceramide, are involved in the signal transduction. In toxicological experiments, TNF had no neurotoxicity. Moreover, a 12 hr pretreatment of TNF protected neurons against NMDA-induced neurotoxicity. This protective effect of TNF was cancelled by 4-aminopyridine, an A-current blocker, suggesting that the increase of A-current densities induced by TNF contributes to the neuroprotection.

9452014

Differential distribution of stathmin and SCG10 in developing neurons in culture.

The neuron-specific protein SCG10 and the ubiquitous protein stathmin are two members of a family of microtubule-destabilizing factors that may regulate microtubule dynamics in response to extracellular signals. To gain insight into the function of these proteins in the nervous system, we pared their intracellular distribution in cortical neurons developing in culture. We have used double-immunofluorescence microscopy with specific antibodies for stathmin and SCG10 bination with antibodies for axonal, microtubule, and synaptic marker proteins. Stathmin and SCG10 were coexpressed in individual neurons. While both proteins were highly expressed in developing cultures during differentiation, their subcellular localization was strikingly different. Stathmin showed a cytosolic distribution, mainly in cell bodies, whereas SCG10 strongly labeled the growth cones of axons and dendrites. During neurite outgrowth, SCG10 appeared as a single concentrated spot in a region of the growth cone where the microtubules are known to be particularly dynamic. Disassembly of labile microtubules by nocodazole caused a dispersal of the SCG10 staining into punctate structures, indicating that its subcellular localization is microtubule-dependent. Upon maturation and synapse formation, the levels of both stathmin and SCG10 decreased to e undetectable. These observations demonstrate that the expression of both proteins is associated with neurite outgrowth and suggest that they perform their roles in this process in distinct partments.

9452015

Negative and positive regulation of astrocyte DNA synthesis by ethanol.

Ethanol suppression of astrocyte mitogenesis is well recognized but ethanol, under some conditions, has also been shown to stimulate astrocyte proliferation. This study addressed the role of protein kinase C and other mitogenic factors as mechanisms responsible for the bidirectional effects of ethanol on astrocyte DNA synthesis. Ethanol treatment inhibited astrocyte DNA synthesis both at 4 hr (short term) and 24 hr (long term) in serum free medium. In contrast, when the medium contained serum, ethanol was less effective in inhibiting DNA synthesis at 4 hr and treatment with ethanol for 24 hr increased DNA synthesis. Protein kinase C activity was increased in cells treated with ethanol for either 4 or 24 hr. Ethanol inhibition of DNA synthesis in serum free medium was not reversed by down regulating protein kinase C. In contrast, downregulating protein kinase C activity by continuous treatment with phorbol myristic acetate partially reversed the effect ethanol had on DNA synthesis. Also, directly inhibiting protein kinase C with H-7 in cells maintained and treated in the presence of serum abolished the stimulatory effect ethanol had on DNA synthesis. It appears that the negative regulation of astrocyte DNA synthesis by ethanol occurs by protein kinase C and serum independent mechanisms whereas adaptive or stimulatory effects of ethanol on astrocyte DNA synthesis requires the interaction of protein kinase C with other factors present in serum.

9452016

Intracerebral injection of interferon-gamma inhibits the astrocyte proliferation following the brain injury in the 6-day-old rat.

The present study examines the influence of interferon-gamma (IFN-gamma) on the astrocyte proliferation in the rat brain injured within the early period of postnatal development. Six-day-old male rats received a lesion in the left cerebral hemisphere and a single injection of binant rat IFN-gamma into the lesion cavity. One or 2 days after the injury the rats were injected with 3H-thymidine. Brain sections were immunostained for glial fibrillary acidic protein (GFAP), subjected to autoradiography, and examined microscopically to record proliferating GFAP-immunopositive astrocytes labeled with 3H-thymidine. In the IFN-gamma-injected rats, a statistically significant decrease in the intensity of reactive astrocyte proliferation was revealed. On day 1 after injury the intensity of astrocyte proliferation showed dose-dependent changes. Relations between the astrocyte reactivity and multiple factors existing in the injured and IFN-gamma-injected brain are discussed. The results represent the first in vivo evidence of a dose-dependent action of IFN-gamma on the astrocyte proliferation in response to injury.

9452017

Lipopolysaccharide enhances synthesis of brain-derived neurotrophic factor in cultured rat microglia.

Expression of neurotrophins in pure microglia cultured from embryonic rat brain and the effects of lipopolysaccharide (LPS) on the expression were investigated. In untreated cultures, nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin (NT)-4/5 mRNAs were detected by use of reverse transcriptase-polymerase chain reaction but NT-3 mRNA was not. LPS stimulation caused a marked increase in BDNF mRNA expression in addition to a slight increment of the NT-4/5 mRNA level; however, the NGF mRNA level was not affected. LPS also increased BDNF-like immunoreactivity in cultured microglia, an action consistent with an elevation of BDNF mRNA. These results demonstrate that LPS stimulates synthesis of BDNF and probably NT-4/5, specific ligands for tyrosine kinase receptor TrkB, suggesting that activated microglia, which appear in the damaged brain, participate in neuronal regeneration via production of such neurotrophins.

9452018

Stabilization of myelin mRNAs as measured in a brain slice system.

The stabilization and destabilization of myelin mRNA is increasingly recognized as a major control point in regulating myelin gene expression. A brain slice system was developed and characterized to study mRNA stability in actively myelinating oligodendrocytes. The mRNA half-life of a major CNS myelin protein, proteolipid protein (PLP), was measured to be 5 hr. The half-life of another CNS myelin protein mRNA, myelin basic protein (MBP), was measured to be greater than 12 hr. A long half-life for MBP mRNA is consistent with MBP mRNA being stable long enough to be translocated to the myelin internode where it is then translated. Using semi-quantitative reverse transcriptase-PCR, it was determined that there was no differential stabilization between the two major PLP mRNA isoforms, PLP and DM20. It was also determined that protein synthesis was required for the specific stabilization of PLP/DM20 mRNAs. Inasmuch as PLP is a major structural protein of the CNS myelin, the PLP/DM20 mRNAs have relatively short half-lives. However, the PLP/DM20 mRNAs half-lives may be increased by the action of trans-acting factors that are themselves very labile.

9452019

Regulation of norepinephrine release from the rat bed nucleus of the stria terminalis: in vivo microdialysis studies.

The microdialysis technique was used to study the in vivo extracellular levels of norepinephrine in the bed nucleus of the stria terminalis. A basal level of 2.34 +/-0.25 fmol/microl of norepinephrine was observed. Desipramine (2 and 10 microM), a norepinephrine uptake blocker, significantly increased extracellular levels of norepinephrine. Reversed perfusion with high potassium in the presence of 2 microM desipramine induced the release of norepinephrine. Instead, in the presence of 10 microM desipramine, a significant decrease in the induced release of norepinephrine was observed. Clonidine, an alpha2-adrenergic agonist, significantly decreased basal extracellular levels of norepinephrine and the K+-induced release of norepinephrine. In contrast, yohimbine and RX821002, two alpha2-adrenergic antagonists, significantly increased basal extracellular levels of norepinephrine but not the release of norepinephrine induced by 70 mM K+. Perfusion of tetrodotoxin through the probe located in the bed nucleus of the stria terminalis significantly decreased both the basal extracellular level and the K+-induced release of norepinephrine. Furthermore, perfusion of tetrodotoxin through a microdialysis probe implanted in the medial forebrain bundle also decreased basal extracellular levels of norepinephrine in the bed nucleus of the stria terminalis. The results show that in vivo there is a significant noradrenergic tonic activity in the bed nucleus of the stria terminalis. This tonic activity depends on the impulse flow through medial forebrain bundle nerve fibers. Under these conditions, extracellular levels of norepinephrine in the bed nucleus of the stria terminalis are regulated by the magnitude of norepinephrine uptake and by presynaptic alpha2-adrenergic receptors.

9452020

Fatty acid amide hydrolase, the degradative enzyme for anandamide and oleamide, has selective distribution in neurons within the rat central nervous system.

Fatty acid amide hydrolase (FAAH) is a membrane-bound enzyme activity that degrades neuromodulatory fatty acid amides, including oleamide and anandamide. A single 2.5-kb FAAH mRNA is distributed throughout the rat CNS and accumulates progressively between embryonic day 14 and postnatal day 10, remains high until postnatal day 30, then decreases into adulthood. FAAH enzymatic activity, as measured in dissected brain regions, was well correlated with the distribution of its messenger RNA. In situ hybridization revealed profound distribution of FAAH mRNA in neuronal cells throughout the CNS. The most prominent signals were detected in the neocortex, hippocampal formation, amygdala, and cerebellum. The FAAH distribution in the CNS suggests that degradation of neuromodulatory fatty acid amides at their sites of action influences their effects on sleep, euphoria, and analgesia.

9452021

Expression of the GABA(A) receptor alpha6 subunit in cultured cerebellar granule cells is developmentally regulated by activation of GABA(A) receptors.

Primary cultures of cerebellar granule cells, prepared from cerebella of 7-day-old rats and cultured for 4 or 8 days, were used to study the neurodifferentiative effect of a GABA(A) receptor agonist, 4,5,6,7-tetrahydroisoxazol[5,4-c]pyridin-3-ol (THIP), on the expression of the alpha6 GABA(A) receptor subunit. Membranes prepared from these cultures were photolabeled with the imidazobenzodiazepine [3H]Ro15-4513. In THIP-treated cultures at 4 days in vitro (DIV), photolabeled [3H]Ro15-4513 binding in membranes was significantly increased for both the 51 kilodalton, kDa, (alpha1 subunit) and 56-kDa (alpha6 subunit) radioactive peaks in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In contrast, THIP-treated granule cells at 8 DIV demonstrated a small but significant decrease from control cultures in the photoincorporation of [3H]Ro15-4513 in the 51-kDa peak; however, no significant change in [3H]Ro15-4513 binding was observed for the 56-kDa polypeptide. Immunolabeling of the alpha6 subunit using silver-enhanced, immuno-gold staining of granule cells showed a significant effect with THIP treatment only at 4 DIV and not at 8 DIV. Examination by light microscopy demonstrated that the major effect of THIP was to increase alpha6 subunit clustering on granule cell bodies as well as neurites, 15-fold and sixfold, respectively. Using in situ hybridization, a small THIP-induced increase in alpha6 mRNA was detected at 4 DIV; however, no effect was apparent at 8 DIV. These data suggest that THIP has a trophic effect on alpha6 subunit expression, and this effect occurs only at an early developmental stage. Moreover, this study presents further evidence for the role of GABA(A) agonists, and thus the neurotransmitter, GABA, in regulating the expression of GABA(A) receptor subunits in the developing cerebellum.

9452079

The first pathogenic mitochondrial methionine tRNA point mutation is discovered in splenic lymphoma.

We describe a novel point mutation in the mitochondrial DNA transfer RNA methionine gene, a G-to-A transition at position 4450, in a patient with a splenic lymphoma with villous lymphocytes. The patient's lymphocytes were remarkable by the presence of large cytoplasmic inclusions demonstrated as abnormal mitochondria by electron microscopy and led to the discovery of the mutation using denaturing gradient gel electrophoresis as a screening procedure. The pathogenic potential of the mutation was clearly established by the following criteria. It was absent in a control population. It involves a nucleotide that is highly conserved along the phylogenetic tree. The mutation was heteroplasmic and, when present in a high proportion, was associated with morphological alterations of the mitochondria, with defects of respiratory plexes activities and with a decrease in the mitochondrially encoded cytochrome c oxidase subunit II. Transfer of the mutation in Rho0 cells allowed to demonstrate its association with a severe respiratory chain dysfunction. However, although the pathogenicity of the mutation was clearly demonstrated, its link with the patient disease remained disputable.

9452123

Pneumolysin: a multifunctional pneumococcal virulence factor.

Pneumolysin (PLY) is a multifunctional pneumococcal virulence factor that appears to augment intrapulmonary growth and dissemination during the early pathogenesis of Streptococcus pneumoniae infection. Through its cytotoxicity to respiratory epithelium and endothelium, PLY disrupts pulmonary tissue barriers that serve as mechanical pulmonary defenses, thus facilitating S. pneumoniae growth and dissemination. Through direct inhibitory effects on immune and inflammatory cells and by plement, PLY inhibits bacterial clearance from the pulmonary interstitium and the blood. Because PLY stimulates local and systemic immune responses and enhances the immunogenicity of S. pneumoniae polysaccharide (PS), PLY-PS conjugates may form the basis for vaccines that not only induce protective and durable immune responses to pneumococcal PS but also generate neutralizing anti-PLY antibodies that can protect the respiratory mucosa from toxin-induced injury.

9452124

Temporal induction of clusterin in the peri-infarct zone after experimental myocardial infarction in the rat.

Clusterin, a glycoprotein with potent cellular cohesive properties, is induced in many organs at times of tissue injury or remodeling. After renal infarction, for example, clusterin is localized to tubular epithelial cells in the peri-infarct zone. The purpose of this study was to examine the spatial and temporal expression of cardiac clusterin after myocardial infarction. Sprague-Dawley rats underwent permanent coronary ligation or sham operation. Hearts were harvested at 6 hours and at 2, 14, and 28 days after infarction. Cardiac clusterin expression was examined by immunohistochemistry and in situ hybridization. Left ventricular clusterin staining was evident at 6 hours and 2 days after myocardial infarction, although not at later time periods. Clusterin was localized to peri-infarct zone myocytes and endothelial cells of this region, and local synthesis of clusterin by myocytes was confirmed by in situ hybridization. Clusterin was not present in inflammatory cells or in left ventricular tissue distant from the infarct. The distribution of clusterin was different from the membrane plex plement (C5b-9), with the latter being present diffusely throughout the infarct zone. Although the role of cardiac clusterin is not known, we speculate that clusterin's cohesive properties serve to promote myocyte interactions that are perturbed in the peri-infarct zone after myocardial infarction.

9452125

Modulation of lipopolysaccharide-mediated activation in rat Kupffer cells by antioxidants.

Activation of Kupffer cells, the resident macrophage population of the liver, has been implicated in the pathogenesis of several types of liver injury. The aim of this study was to investigate whether the antioxidants N-acetylcysteine (NAC) and alpha-tocopherol succinate (alpha-TOC) suppress lipopolysaccharide (LPS)-induced activation of rat Kupffer cells. LPS activated NF-kappaB in Kupffer cells, and this response was inhibited by NAC and alpha-TOC. NAC and alpha-TOC also markedly suppressed LPS-induced tumor necrosis factor-alpha (TNF-alpha) mRNA levels and secretion. We further show that LPS was unable to increase TNF-alpha mRNA in drug-treated cells even when stimulation occurred after NAC or alpha-TOC were removed. These results indicate that antioxidants persistently suppress LPS activation in Kupffer cells, and suggest that the mechanism responsible for this involves more than mere quenching of free radical production. The demonstration that NAC and alpha-TOC have inhibitory effects on LPS-mediated Kupffer cell activation suggests that pounds may have a beneficial effect in liver injury involving oxidative stress and endotoxemia.

9452126

Hypoxia regulates endothelin-1 production by the inner medullary collecting duct.

Renal endothelin-1 (ET-1 ) production is increased by hypoxia and has been implicated in ischemia-induced renal hypoperfusion. Because the inner medullary collecting duct (IMCD) is a major source of ET- 1 in the kidney, and because ET- 1--in the setting of ischemic renal failure-may alter medullary perfusion, we sought to determine whether hypoxia modulated ET-1 production by IMCD cells. Primary cultures of rat IMCD cells were exposed to 21%, 3%, or 0%O2. IMCD ET-1 secretion significantly increased after exposure of cultures to 3% O2 (114.1% +/- 4.7% increase over control value) and 0%O2 (171.7% +/- 7.9% increase). ET-1 mRNA levels, as determined by reverse transcription-polymerase chain reaction, also increased 2.5-fold after 24-hour exposure to 0% O2. We speculate that a hypoxia-induced increase in IMCD ET-1 production plays a role in modulating renal medullary perfusion during ischemic renal failure.

9452127

Ristocetin-mediated interaction of human von Willebrand factor with platelet glycoprotein lb evokes a transient calcium signal: observations with Fura-PE3.

High shear stress in narrowed arteries causes von Willebrand factor (vWf) to bind to its platelet receptor, glycoprotein Ib (GpIb). This binding is reported to promote an increase in intracellular free calcium concentration ((Ca2+)i), which may be responsible for platelet activation. The present study examined the platelet (Ca2+)i signal that arises when ristocetin mediates vWf-GpIb binding. Platelet (Ca2+)i was monitored with Fura-PE3 (Vorndran C, Minta A, Poenie M. Biophys J 1995;69:2112-24), a new ratiometric calcium indicator. Fura-PE3 has calcium-binding characteristics (Kd = 146 nmol/L) and fluorescent properties similar to those of Fura-2. However, its zwitterionic nature ensured much slower extrusion from the platelet (0.2% per minute) than that for Fura-2. This eliminated one of the technical problems that seriously distorted previous measurements of vWf-induced changes in platelets (Ca2+)i. Design of a novel stirring arrangement avoided the other major problem, which is the tendency of platelet aggregates to settle to the bottom of the cuvette, beneath the detection zone of the spectrofluorometer. With Fura-PE3 and the new stirrer used in the present study, vWf-induced changes in (Ca2+)i could be measured reliably in aggregating platelets. Ristocetin-mediated vWf-GpIb binding induced a transient increase in platelet (Ca2+)i. This increase occurred after a significant lag phase; platelet (Ca2+)i rose gradually, followed by a decline to almost the resting level. Binding of vWf to platelet Gplb was responsible for the (Ca2+)i signal. A similar signal was found in the absence of extracellular calcium. These characteristics differ substantially from those described in previous reports, in which the vWf-induced rise in (Ca2+)i was attributed to calcium influx through channels in the plasma membrane. Data from those earlier studies, however, were severely distorted by indicator extrusion and loss of platelet aggregates. The present findings are a more accurate representation of the vWf-induced platelet (Ca2+]i signal.

9452128

Cyclosporine A nephrotoxicity: role of thromboxane and reactive oxygen species.

The main adverse effect of cyclosporine A (CyA) is nephrotoxicity. CyA increases urinary concentrations of thromboxane A2 (TXA2), a potent vasoconstrictor that can be involved in kidney failure induced by CyA. Furthermore, it has been postulated that a relationship exists between oxygen free radicals and the synthesis of arachidonate metabolites in experimental models of CyA nephrotoxicity. We studied the effect of vitamin E (VitE), an oxygen free radical scavenger, on renal function, on glomerular synthesis of thromboxane B2 (TXB2), and on free radicals in rats treated with CyA. Four groups of male Wistar rats were studied: (1) a control group; (2) a group given VitE at 0.05 mg/dl in drinking water for 25 days; (3) a group given CyA at 50 mg/kg body weight/day orally for 10 days; and (3) a group given Vit E + CyA, in which rats were provided with drinking water containing VitE for 15 days and afterwards were treated with VitE and CyA for 10 days. Renal function parameters and glomerular synthesis of TXB2, superoxide anion (02.-), malondialdehyde (MDA), and hydrogen peroxide (H202) were evaluated. CyA decreased body weight, caused deterioration of kidney function and increased glomerular synthesis of TXB2, O2.-, MDA, and H202. Pretreatment with VitE prevented the effects of CyA on kidney function and decreased glomerular synthesis of these mediators. In conclusion, CyA induced glomerular synthesis of reactive oxygen species (ROS) and TxB2. Pretreatment with VitE inhibited acute renal failure induced by CyA, probably by scavenging free radicals and by inhibiting the synthesis of TXB2.

9452129

Experimental use of raffinose as an osmotic agent for peritoneal dialysis.

Conventional glucose-based solutions for peritoneal dialysis fluids have been shown to raise problems of patibility. We therefore evaluated the ultrafiltration capabilities of raffinose as an alternative osmotic agent in a non-uremic rat model. Animals were divided into four groups and injected intraperitoneally with solutions containing raffinose (4.5%, 345 mOsm/kg; 16.7%, 518 mOsm/kg) or glucose (1.5%, 346 mOsm/kg; 4.25%, 489 mOsm/kg). Data obtained from animals exposed to 16.7% raffinose were excluded because of precipitation of the osmotic agent. Low-osmolality raffinose solution induced higher ultrafiltered volume than the low-osmolality glucose-enriched fluid at 120 minutes of dwelling time. No significant differences were observed in effluent sodium and potassium concentration and protein dialysate-to-plasma (D/P) ratio. The D/P ratio of phosphate was higher in the low-osmolality raffinose-based fluid than in the low-osmolality glucose solution. The osmolality of the solutions was significantly decreased after a dwelling time of 120 minutes. We conclude that 4.5% raffinose is an effective osmotic agent. Total or partial replacement of glucose by raffinose for clinical peritoneal dialysis could be eventually considered after appropriate evaluation of its patibility and general side effects.

9452130

Endotoxin-induced disseminated intravascular coagulation in rabbits: effect of recombinant hirudin on hemostatic parameters, fibrin deposits, and mortality.

We evaluated the effect of r-hirudin on an experimental model of disseminated intravascular coagulation (DIC) in rabbits, through the continuous infusion of 100 microg/kg/hr of Escherichia coli endotoxin for a period of 6 hours. r-Hirudin (0.05, 0.3, and 0.6 mg/kg/hr) as treatment, or saline solution as placebo, were administered simultaneously with endotoxin. Severe DIC in the endotoxin control group was shown by impairment in hemostatic parameters, kidney fibrin deposition, and a high mortality rate. Medium and high doses of r-hirudin led to an improvement in such DIC-related parameters as platelet numbers and fibrinogen and protein C concentrations. High-dose r-hirudin also reduced consumption of antithrombin III (ATIII). All doses of r-hirudin prevented decreases in tissue plasminogen activator (t-PA) and reduced the increase in plasminogen activator inhibitor-1 (PAI-1) activity observed at 2 hours after endotoxin administration. A significant reduction in kidney fibrin deposition was seen in medium- and high-dose r-hirudin groups. Additionally, the mortality rate in rabbits receiving medium- and high-dose r-hirudin was 10%, and that in rabbits receiving low-dose r-hirudin was 20%, pared with a mortality rate of 70% in the control group. Protein C activity was significantly lower (p < 0.001) in nonsurviving rabbits. Moreover, there was a strong positive correlation (r = 0.68, p < 0.001) between protein C consumption and kidney fibrin deposition. We conclude that r-hirudin can be a useful drug in the clinical treatment of DIC.

9452131

Platelet adhesion onto artificial surfaces: inhibition by benzamidine, pentamidine, and pyridoxal-5-phosphate as demonstrated by flow cytometric quantification of platelet adhesion to microspheres.

An appreciable effort is directed toward designing strategies to minimize platelet interactions with artificial surfaces, because their reactivity is thought to promote thrombus formation and lead to materials failure. Although platelet glycoprotein Ib/IX (GPIb/IX) and glycoprotein IIb/IIa (GPIIb/IIIa) receptors are thought to mediate adhesion, whether GPIIb/IIIa receptors are activated and how this might occur are largely unknown and are the focus of this article. There are a few ways, other than thrombin generation, that blood contact with artificial surfaces can lead to GPIIb/IIIa activation. Complement activation can lead to products capable of activating platelets (C1q, C5b-9), and contact between platelet CD32 (FcgammaRII) receptors and immobilized immunoglobulin G could also activate platelets. In this article the potential role of these processes was evaluated by using various inhibitors in a microsphere-based platelet adhesion immunoassay. Polystyrene microspheres (10 microm) were incubated in platelet-rich plasma before flow cytometric analysis of beads for adherent platelets. The data eliminated occupancy of the FcgammaRII receptor (by use of IV.3 blocking antibody), C5b-9 production (by use of sCR1), and the indirect action of factor XIIa ponents (by use of corn trypsin inhibitor) as playing roles in supporting platelet adhesion. Agents directed against the ponent (benzamidine, pentamidine, pyridoxal-5-phosphate) were effective inhibitors of platelet adhesion and were also demonstrated to inhibit SC5b-9 and C3d levels on the bead surface after serum incubations. Because these agents are not highly specific, it can not be concluded that C1q is a mediator of adhesion. These agents were also demonstrated to inhibit fluorescein isothiocyanate-fibrinogen binding to activated washed platelets, therefore indicating that fibrinogen receptor expression is a requirement for platelet adhesion.

9452132

Streptococcal and staphylococcal superantigen-induced lymphocytic arteritis in a local type experimental model: comparison with acute vasculitis in the Arthus reaction.

Many pathogenic bacteria produce superantigenic exotoxins. To study their pathogenetic role, in particular to test whether these toxins are able to induce vasculitis, we developed a local-type experimental model in rabbits. Toxins were injected along the intermediate auricular artery of the ear. The histology of ear skin, including the artery, was examined after single or repeated injections. Repeated injections of streptococcal erythrogenic toxins produced chronic-type arteritis characteristic of lymphocytic infiltration, whereas single injection induced no acute-type vasculitis. Staphylococcal enterotoxin B and toxic shock syndrome toxin-1 also induced the same type of arteritis, although weaker in degree. In human patients these lesions are similar to those of Kawasaki disease, a systemic vasculitis with unknown etiology. The Arthus reaction to human serum albumin in immunized rabbits included acute-type vasculitis similar to polyarteritis nodosa when examined in this model. Microvasculitis lesions similar to leukoclastic vasculitis bined in the Arthus reaction but not in the superantigen-induced lesions. Our experimental model described here is widely applicable to the study of the etiology and pathogenesis of human diseases involving vasculitis lesions.

9452133

Postsurgical reduction of serum lipoproteins: interleukin-6 and the acute-phase response.

In a previous retrospective study, we reported a significant reduction in serum cholesterol levels following major surgery, and speculated on the possible role of cytokines in this reduction. The purpose of this article is to report a prospective study of the association of cytokines with postoperative changes in serum lipoprotein levels. Serum samples were obtained from 11 male patients before and at intervals for up to 10 days after surgery, and were assayed for total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), cortisol, tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), and interferon-gamma (IFN-gamma). LDL-C was calculated. The TC showed a 27.9% decrease, from a mean of 4.27 mmol/L to 3.08 mmol/L (p < 0.001) after surgery, reaching a nadir at 24 hours and returning to preoperative values in 7 to 10 days. A similar decrease was noted in the HDL-C and LDL-C levels. IL-6 levels increased from a mean baseline value of 6 pg/ml to a peak of 143 pg/ml at 24 hours (p < 0.0006). There was an inverse relationship between TC and IL-6 levels, with r = -0.51 for the entire curve and r = -0.90 for the cholesterol nadir with the IL-6 peak. The other cytokines did not show significant changes. We conclude that TC and its fractions decrease to a nadir and that IL-6 increases to a peak approximately 24 hours after major surgery. There is a significant inverse correlation between TC and IL-6, suggesting a possible role of IL-6 in postoperative changes in serum lipoproteins.

9452135

A review of the characteristics of the protein required for the acute regulation of steroid hormone biosynthesis: the case for the steroidogenic acute regulatory (StAR) protein.

The acute regulation of steroid hormone biosynthesis requires the de novo synthesis of a protein whose function is to effect the transfer of cholesterol from the outer to the inner mitochondrial membrane where it is cleaved to pregnenolone. This review attempts to summarize the list of this protein's characteristics, which have emerged as a result of experimental observations, and to make the case that the Steroidogenic Acute Regulatory (StAR) Protein is the acute regulator of steroid hormone synthesis.

9452136

Structure and function of the peripheral-type benzodiazepine receptor in steroidogenic cells.

Steroidogenesis depends on the rate of cholesterol transport from intracellular stores to the inner mitochondrial membrane cytochrome P-450 side-chain cleavage enzyme. Using steroidogenic cell submitochondrial fractions, mitochondrial preparations, various cell models, and animal models and with the help of pharmacological, biochemical, morphological, and molecular approaches, we provide evidence that the peripheral-type benzodiazepine receptor mediates the intramitochondrial cholesterol transport and the subsequent adrenal, gonadal, placental, and brain steroid biosynthesis.

9452137

Mechanisms of antineoplastic action of somatostatin analogs.

Over the past decade, impressive antineoplastic activity of somatostatin analogs has been demonstrated in many tumor models. More recent research has provided information regarding mechanisms underlying the antiproliferative and apoptosis-inducing actions of pounds. These include both 'direct' mechanisms that are sequellae of binding of somatostatin analogs to somatostatin receptors present on neoplastic cells and 'indirect' mechanisms related to effects of somatostatin analogs on the host. The upregulation of intracellular tyrosine phosphatase activity triggered by binding of ligands to the type II somatostatin receptor has received considerable attention as a direct mechanism, not only because this activity is the converse of the tyrosine kinase activity associated with many peptide mitogen receptors, but also because the type II somatostatin receptor is frequently expressed mon human neoplasms, including breast cancer. The potential importance of indirect mechanisms of action of somatostatin analogs, such as alterations in host insulin-like growth factor physiology, is emphasized by the in vivo antineoplastic activity of pounds against somatostatin receptor-negative neoplasms. Clinical efficacy and a favorable toxicity profile of somatostatin analogs in the treatment of relatively mon conditions such as acromegaly and neuroendocrine tumors have already been demonstrated. Preclinical data now are sufficient to justify controlled clinical trials in breast, prostate, and pancreatic cancer. The development of monthly depot formulations will facilitate the clinical evaluation of somatostatin analogs for these and other indications.

9452138

Prostaglandin-independent stimulation of bone resorption in mouse calvariae and in isolated rat osteoclasts by thyroid hormones (T4, and T3).

The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), were found to enhance both neonatal mouse calvarial bone resorption and pit formation on bovine slices by isolated rat osteoclasts. Dosage-dependent release of 45Ca from mouse calvarial bones was observed after 120 hr of culture with 10(-6)-10(-8) MT4 and 10(-6)-10(-10) M T3. Maximum treatment/control ratios of 45Ca release were recorded for 10(-7) M T4 and 10(-8) MT3. Inhibition of 45Ca release stimulated by 10(-8) M T3 was observed in the presence of 30 nM salmon calcitonin at 48 hr and 120 hr of culture with no indication of "escape" by T3-treated bones. In contrast, stimulation of 45Ca release from mouse calvarial bones by 10(-7) MT4 and 10(-8) MT3 was not inhibited by 10(-6) M indomethacin. Formation of PGE2 and PGI2 (evaluated by measuring 6-keto-PGF1alpha) by mouse calvariae was also not increased by 10(-8) MT3 after 120 hr of culture. Furthermore, no increases in cAMP formation were observed in calvarial bone cultures after either 10 min or 24 hr of exposure to 10(-8) MT3. However, significant inhibition of 45Ca release stimulated by 10(-8) M T3 was found at 120 hr in the presence of 10(-3) M hydroxyurea. When isolated rat osteoclasts were cultured in the presence of 10(-7) MT3, a 1.4-fold stimulation of pit number was observed. Pit formation was not affected by addition of 10(-6) M indomethacin to either the control or T3-treated cultures. These data suggest that the stimulation of bone resorption in neonatal mouse calvariae and activation of isolated rat osteoclasts by the thyroid hormones is not related to either prostaglandin or cAMP formation. In mouse calvariae, the effect on bone resorption of the thyroid hormones is dependent on increased cellular replication, perhaps of osteoclast precursors, or other bone cells involved in the resorptive process.

9452139

Prevention of corticosteroid-induced bone loss with alendronate.

The putitive bone-sparing effect of alendronate was tested in two animal models of osteopenia: estrogen-deficient female rats and glucocorticoid-treated male rats. In the first study, 18 female Sprague-Dawley rats, 4 months of age, were ovariectomized (OVX), and an additional 6 rats were sham-operated. The OVX rats were treated with either vehicle, 17beta-estradiol (E2) (100 microg/rat/week, s.c.), or alendronate (1 mg/kg/day, on alternate days, orally). In the second study, 24 8-month-old male Wistar rats were treated with either vehicle, methyl prednisolone (7 mg/kg once a week, s.c.), prednisolone plus testosterone (16 mg/kg once every 3 weeks, i.m.), or prednisolone plus alendronate (20 microg/kg twice a week, s.c.). Prior to treatment and at the end of the 6-week treatment period, bone mineral density (BMD) of the lumbar spine was measured by dual energy x-ray absorptiometry, and mean femur weights were calculated. The OVX rats had subnormal BMD (-3.91 +/- 1.0% vs control +5.19 +/- 3.92%, P < 0.05) and femur weights (720 +/- 6 mg vs %; 746 +/- 11 mg, P < 0.05). OVX-induced bone loss pletely abolished by the administration of E2 (7.01 +/- 2.32%, P < 0.005; 748 +/- 6 mg, P < 0.01), or alendronate (24.2 +/- 2.73%, P < 0.0001; 779 +/- 11 mg, P < 0.001). In the second study in older male rats, glucocorticoids significantly decreased BMD (-9.70 +/- 3.44% vs -1.10 +/- 1.75%, P < 0.05), and femur weight (1070 +/- 14 mg vs 1180 +/- 24 mg, P < 0.01). itant administration of testosterone (BMD 4.23 +/- 1.84%, P < 0.005; femur weight 1260 +/- 56 mg, P < 0.02), or alendronate (BMD 8.18 +/- 1.36%, P < 0.001; femur weight 1360 +/- 50 mg) with prednisolone, abolished the corticosteroid-induced bone loss. Bone histomorphometry showed a 34% loss of trabecular bone volume in glucocorticoid-treated rats (P < 0.05), which was prevented with both testosterone and alendronate therapies. However, at the doses used in both models, alendronate was more efficacious than either E2 or testosterone in increasing BMD and femur weight. In summary, this study demonstrated that alendronate therapy is highly effective in counteracting the osteopenia of OVX and glucocorticoid therapy.

9452140

Longer-term fourth ventricular 5-thioglucose infusion increases body fat in the rat.

5-Thioglucose (5-TG) has been shown to increase food intake after acute administration. To determine the longer-term effects of 5-TG on feeding and position, thirty-four female Sprague-Dawley rats were cannulated into the fourth ventricle and infused with artificial CSF and either 0.01 M 5-TG or 0.1 M 5-TG using osmotic pumps. Food intake and body weight were monitored daily. Rats were killed after 14 days of infusion. Carcass and fatpad weights were measured, and positions were determined. Food intake was not different during the first week of infusion; however, cumulative food intake was decreased in the 0.1 M 5-TG group during the second week pared to the CSF control group. Body weight and carcass weight of this group also decreased pared to the control. The group receiving the higher dose of 5-TG (0.1 M) had increased fatpad weights in all three depots examined (inguinal, retroperitoneal, and perimetrial depot); the group with lower dose of 5-TG infusion (0.01 M) increased the fatpad weights in the retroperitoneal and perimetrial depot, pared to the CSF group. Data from the position analysis were consistent with the results of the fatpad weights. In conclusion, the present study demonstrated that chronic fourth ventricular 5-TG infusion increased body fat without increasing food intake, suggesting that energy expenditure is decreased under this condition. The results of this study indicate that glucose metabolism in the hindbrain is important in the control of energy expenditure, body fat deposition, and thus energy balance regulation.

9452141

Bile-pancreatic juice-independent increases in pancreatic proteases and intestinal cholecystokinin by dietary protein in rats.

Luminal bile-pancreatic juice (BPJ) is involved in the induction of pancreatic proteases in rats fed a high-protein diet. Recently, we have demonstrated that a BPJ-independent mechanism is responsible for enhancement of pancreatic secretion after feeding of a dietary protein in chronic BPJ-diverted rats. The aim of the present study was to explore the existence of a BPJ-independent mechanism during adaptation of the exocrine pancreas to dietary protein. Rats, whose BPJ was diverted into the ileum through mon bile-pancreatic duct catheter for 5 days (PBD rat), were fed a fat-free diet containing 25% or 60% casein for 3 days. Messenger RNA levels for pancreatic enzymes, cholecystokinin, and secretin in the jejunal mucosa were evaluated by northern blotting method. Pancreatic trypsin and chymotrypsin activities and mRNA levels of their zymogens were higher in PBD rats than in rats whose diverted BPJ was returned into the duodenum (PBD returned rat). In the PBD groups, pancreatic protease activities were further increased by 3-day feeding of a high-protein diet without changes in mRNA levels of these proteases. Cholecystokinin mRNA was increased after feeding of a high-protein diet in the PBD rats. These results indicate that pancreatic proteases are induced by feeding a high-protein diet by a mechanism independent of luminal BPJ, which is associated with an increase in intestinal cholecystokinin mRNA level.

9452142

Effects of protein tyrosine phosphatase inhibitors on EGF- and insulin-dependent mammary epithelial cell growth.

Epidermal growth factor (EGF)- and insulin-dependent mammary epithelial cell mitogenesis is mediated by specific tyrosine kinase receptors. Receptor tyrosine kinase activity is highly regulated in normal cells, whereas amplification of intracellular protein tyrosine phosphorylation is associated with abnormal growth and/or neoplastic transformation. Since protein tyrosine phosphatases (PTPs) are involved in regulating receptor tyrosine kinase signaling, studies were conducted to determine the effects of the PTP inhibitors, vanadate and pervanadate, on mitogen-receptor signal transduction and cell growth. Mammary epithelial cells isolated from midpregnant BALB/c mice were grown within collagen gels and maintained on serum-free media. Treatment with 2-8 microM vanadate or pervanadate greatly increased intracellular protein tyrosine phosphorylation. However, in the presence of optimal mitogenic stimulation (10 ng/ml EGF and 10 microg/ml insulin), these treatments induced a slight, but significant decrease in cell growth. In contrast, these treatments significantly increased mammary epithelial cell growth, albeit less than optimally, under submitogenic culture conditions (500 pg/ml EGF and 10 microg/ml insulin). Neither vanadate nor pervanadate was found to mimic the mitogenic actions of EGF and/or insulin in these cells. The growth-stimulatory effects of PTP inhibitors in submitogenic conditions appear to result from enhanced receptor tyrosine kinase mitogenic signaling, whereas PTP inhibitor attenuation of optimal cell growth may be due to the suppression of PTP activity associated with cell cycle progression. In addition, treatment with PTP inhibitors was not found to stimulate anchorage-independent growth, as determined by the inability of single cells to form colonies in soft agarose. In conclusion, these data demonstrate that optimal mitogen-dependent mammary epithelial cell growth requires both receptor tyrosine kinase and PTP activity. Furthermore, PTP inhibitor-induced amplification of receptor tyrosine kinase mitogenic signaling is not in itself sufficient to induce enhanced cell growth or phenotypic expression of neoplastic transformation.

9452143

Hypophyseal-portal concentrations of growth hormone-releasing factor and somatostatin in conscious pigs: relationship to production of spontaneous growth hormone pulses.

A method of collecting hypophyseal portal blood (HPB) in conscious pigs was used to show the relationship between GRF and somatostatin (SRIF) concentration and peripheral GH response. Six male castrate pigs (approximately 63 kg body weight) had HPB and jugular blood collected individually for an average of 175 min each. Twenty-seven spontaneous GH pulses were detected in the 1050 min of total HPB collection. Of the associations examined, the only significant finding was that GH pulse maxima occurred nonrandomly within periods of SRIF descent (63%; P = 0.005). Although 48% (13/27) of GH pulse maxima were associated with an ascent in portal GRF concentration, these associations were not determined to be nonrandom (P = 0.14). Only 7 of 27 (26%) GH pulse maxima were associated with an ascent in portal GRF concentration and a descent in SRIF concentration occurring simultaneously. A saline infusion given approximately 120 min after beginning blood collection resulted in an increase in SRIF pulse frequency and a decrease in GH-AUC and GRF-AUC. The cause of this saline effect is unknown, but it may have been related to acclimation of the pigs to the blood collection procedure. These data show plexity of the relationship between SRIF and GRF concentrations and GH secretion and may indicate a close relationship with SRIF in GH pulse generation in the pig. In addition, these data support the hypothesis that, in the pig, mediation of GH release cannot be explained simply by antagonism between GRF and SRIF.

9452144

Resazurin reduction assay for ram sperm metabolic activity measured by spectrophotometry.

Resazurin (7-hydroxy-3H-phenoxazin-3-one 10-oxide) is a redox dye that can be reduced by metabolically active spermatozoa to resorufin and manifested as visual color change from blue (resazurin) to pink (resorufin). This bined the resazurin reduction test with spectrophotometric methods and investigated the correlation between metabolic activity and fertilization potential of spermatozoa, using ram semen as a model. The absorbance at specific wavelengths of resazurin and resorufin was determined by scanning photo spectrometer (600 nm for resazurin and 570 nm for resorufin, respectively). The absorbance at wavelengths of 600 nm (A600) and 570 nm (A570) was measured by spectrophotometry and used to evaluate sperm metabolic activity. A600 decreased and A570 increased in relationship to the increased concentrations of motile spermatozoa and increased resazurin reaction times. We observed, upon using a retrospective experimental design, that fertile rams had greater relative absorbance values than rams with lower fertility. Also, we observed a wide range variation of absorbance between the fertile rams, which is highly correlated to the sperm motility. We conclude that the spectrophotometric measurement of resazurin reduction for sperm activity might be a good assay for ram fertility.

9452146

Effect of human pregnancy-specific beta1-glycoprotein on blood cell regeneration after bone marrow transplantation.

Pregnancy-specific beta1-glycoprotein (PSG) posed of a family of highly homologous proteins initially isolated from human placenta and pregnancy serum. Recent studies showed that PSGs are also present in a number of ectopic sites, including uncultured peripheral blood and bone marrow cells. This report aims at studying the in vivo effect of the PSGs on murine hematopoiesis. The profile of recovery of blood cells after transplantation of viable nucleated bone marrow cells in gamma-irradiated mice with and without the administration of the purified human protein was studied. Five groups of mice were given 0.1 microg human serum albumin, 0.1 microg IL6, 1 microg PSG, 10 microg PSG, and 50 microg PSG, respectively, per mouse per day consecutively for 20 days. The mice were bled once every 2 days, and the platelet and WBC counts were determined using a Nebauer hemacytometer (Hausser Scientific, Buffalo, NY). The recovery of platelet count after bone marrow transplant was much faster in mice receiving 1 microg PSG/day than in animals in any other group. On Day 20 post-transplant, the platelet count of animals in this group reached 178,600 +/- 15,759/microl (mean +/- standard deviation) which was significantly (P < 0.05) higher than that of any other group. On Day 26, the platelet count reached a low normal value of 190,844 +/- 6,380/microl with a range of 185,420-200,500/microl. This value was 3-fold higher than that of the control group (68,600 +/- 15,486/microl in the human serum albumin group). Mice given 1 microg or 10 microg PSG/day also had their WBC count recover significantly faster and achieved a normal value (12,440 +/- 3,680/microl for the 1-microg PSG group, and 12,154 +/- 3,016/microl for the 10-microg PSG group) within the experimental period. On the other hand, the controls, or mice given 50 microg PSG/day did not recover as rapidly and did not achieve a normal WBC count within the experimental period. These results suggest that human placental PSGs enhance platelet and WBC recovery after bone marrow transplant.

9452145

LDL oxidation and human placental trophoblast and macrophage cytotoxicity.

We have previously shown that LDL is oxidized by placental cells in primary tissue culture and that this process causes cytotoxicity proportional to LDL oxidation in the presence of sex steroid hormones. Here we describe further experiments linking LDL oxidation to placental cell cytotoxicity. Trophoblast and macrophages were isolated from healthy elective caesarean section placentas by enzymatic digestion and separated by centrifugation on a 40% Percoll gradient and maintained in primary culture for up to 5 days. LDL was oxidized by exposure to 5 microM CuCl2, cells were incubated in the absence of albumen to favor oxidation, and cytotoxicity was measured by 51Cr release from prelabelled cells and cell protein content. Native LDL was oxidized by both cell types with a 10%-50% increase in lipid peroxides and an approximately 4-fold increase in TBARS formation. Increasing concentrations of native LDL and oxidized-LDL increased 51Cr release and diminished protein content in cells incubated in HAM's F-10 medium. Addition of 5 microM Cu2+ augmented cytotoxicity of LDL in macrophage and trophoblast culture, but more in macrophages than trophoblast. Cytotoxicity was diminished by adding 0.001-0.1 mM EDTA to the system, diminishing 51Cr release from 91 +/- 0.5 to 40.8 +/- 1.0% in macrophages and 54.2 +/- 1.2 to 33.1 +/- 1.3% in trophoblast (P < 0.001 in both instances). Similarly, the absence of transition metal ion in culture (MEM medium) blocked an increase in 51Cr pared to its presence (HAM's F-10 medium). An antioxidant, butylated hydroxytoluene, diminished 51Cr release and LDL electrophoretic mobility in HAM's F-10 medium in placental macrophage culture. LDL oxidation injures placental macrophages and trophoblast, the former more than the latter. The process is LDL- and transition metal ion-dependent and is inhibited by antioxidant. This model of LDL oxidation and placental cell damage in vitro provides a basis for studying mechanisms of placental dysfunction and senescence in human pregnancy.

9452147

Permanent lesions of stored platelets correlate to pH and cell count while reversible lesions do not.

The demand for stored platelet concentrates (PC) for therapeutic transfusions has been increasing for the past three decades. Loss of platelet functionality increases with the length of storage time due to a multitude of factors collectively referred to as a platelet storage lesion. As more of the causes of the storage lesion have been defined, storage conditions have improved along with the therapeutic value of the transfused platelet samples. This report addressed new aspects of the storage lesion correlated with the pH of the storage medium. Platelet function was evaluated as aggregation induced by the synergistic agonist pair, U46619 (TXA2 mimetic) plus epinephrine or the strong agonists SFLLRNP (a peptide thrombin receptor agonist) or thrombin each added alone. Stored PC pared to freshly prepared platelets as platelet-rich plasma (PRP) or washed platelets re-suspended in hepes Tyrode's buffer. The pH of the storage plasma, was inversely proportional to the cell count with platelets stored for 6 days. Agonist-induced platelet aggregation was significantly impaired by storage for 6-7 days as PRP; however, upon washing, a significant level of activity was restored. Washed platelets more accurately reflect conditions of transfused platelets that may regain activity in vivo. There appeared to be two subpopulations of stored PRP samples--one that retained activity and one that lost virtually all activity with the agonists tested. However, the lack of response to agonist observed with one subpopulation was reversed to the same level obtained with the active subpopulation upon washing. The subpopulation of stored PRP samples that were inactive with U46619-plus-epinephrine did not correspond to the subpopulation of samples that were nonresponsive to SFLLRNP, indicating that loss of activity with selected samples was possibly receptor specific. Loss of agonist-induced aggregation with PRP samples did not correlate with storage pH; however, the level of aggregation with washed platelets correlated significantly with pH. Results implied that pH caused a permanent storage lesion that could only be detected with washed platelets. A partially reversible lesion was superimposed on the pH lesion and was only detectable with PRP samples. Results indicate that continued attention must be paid to regulate the pH of stored PC even in the second generation plastic bags.

9452149

Effects of body position on the carbon monoxide diffusing capacity in patients with chronic heart failure: relation to hemodynamic changes.

Pulmonary diffusion has been found to be reduced in patients with congestive heart failure. The effects of postural changes on the diffusing capacity had been evaluated in healthy subjects, but not in patients with heart failure. The aim of this study was to evaluate the posture-induced changes in diffusing capacity in patients with chronic heart failure and their relation to the hemodynamic profile.

9452148

Satiation and masticatory function modulated by brain histamine in rats.

Both the ventromedial hypothalamus (VMH) and the mesencephalic trigeminal sensory nucleus (Me5) are densely innervated by histaminergic neurons. The depletion of neuronal histamine (HA) from the Me5 by the bilateral microinfusion of 448 nmol/rat alpha-fluoromethylhistidine (FMH), a specific suicide inhibitor of histidine decarboxylase, reduced the eating speed and prolonged meal duration, while leaving the meal size unaffected. HA depletion from the VMH increased the size of the meal and prolonged its duration, but not the eating speed. When the HA turnover rate was measured at 15 min after the scheduled feeding following fasting for less than 24 hr, the rate increased in the region including the Me5, but not in the hypothalamus. The turnover rate reached higher levels at 60 min in both regions. Gastric intubation of an isocaloric liquid diet or an equivolume of water with the liquid diet abolished the increase in HA turnover both in the Me5 region and the hypothalamus. The present findings indicate that brain HA thus modulates satiation through both the VMH and masticatory function as well as due to the action of the Me5. The HA function activated by mastication began earlier in the Me5 and later in the hypothalamus due to a signal originating from the oral proprioceptors and initiated by chewing.

9452150

Dual chamber pacing in hypertrophic cardiomyopathy: influence of atrioventricular delay on left ventricular outflow tract obstruction.

The impact of the duration of atrioventricular (AV) delay on obstruction in hypertrophic cardiomyopathy was evaluated in 12 patients by cardiac catheterization, and in 8 of them also by Doppler echocardiography. The AV delay was programmed in random order at 125, 100 and 75 ms in the invasive study and at 120, 100 and 80 ms after pacemaker implantation. The arterial pressure did not changed throughout the studies, whereas the gradient decreased significantly by reducing the AV delay value; the greater gradient reduction was obtained, in both studies, with the AV delay set between 75 or 80 and 100 ms. QRS duration increased significantly by reducing the AV delay during both studies. The widest QRS was not associated with the smallest gradient in all patients. Changes in gradients were similar during the invasive and noninvasive protocols.

9452152

Analysis of the P wave with signal averaging to assess the risk of atrial fibrillation after coronary artery bypass surgery.

P wave signal averaging was performed in 91 consecutive patients undergoing coronary artery bypass grafting to detect patients at risk of postoperative atrial fibrillation (AF). Sixteen patients (17.5%) developed AF after surgery. The P wave duration on the signal-averaged electrocardiogram (ECG) and on surface ECG was prolonged in AF pared to others (respectively 141 +/- 12 vs. 132 +/- 12 ms and 124 +/- 9 vs. 113 +/- 9 ms). The root mean square voltages (RMS) of the total P wave were not different between the two groups; the RMS of the late portion of the P wave (late RMS) was significantly higher (0.25 +/- 0.15 vs. 0.17 +/- 0.10 microV) and the RMS of the first 110 ms of the P wave (early RMS) significantly lower (0.88 +/- 0.28 vs. 1.09 +/- 0.33 microV) in AF. The late/ early RMS ratio was different (0.29 +/- 0.16 vs. 0.17 +/- 0.11). In a multivariate analysis only age and the late/early RMS ratio were predictive for AF.

9452151

Does heart rate variability change in angina pectoris patients treated with spinal cord stimulation?

To determine whether spinal cord stimulation has any effect on the autonomic nervous tone of the heart, heart rate variability was used as an indicator of autonomic nervous control of the heart. ponents time domain and power spectral analyses of heart rate variability were measured in 21 patients with angina pectoris. Twenty-four-hour Holter recordings were obtained before and after 12 months with spinal cord stimulation. No significant attenuation of time domain or ponents of heart rate variability analyses were found. Apparently, spinal cord stimulation does not influence the autonomic tone of the heart.

9452153

A prospective randomized comparison between fixed rate response programming and automatic rate response optimization in activity-triggered DDDR pacemakers. Thera Pacemaker Study Group.

Activity rate response programming depends on the physician's experience and on the limited knowledge of patient's daily activities. The present pares a new continuous automatic adjustment of the activity rate response called rate response optimization (OPT) with fixed activity rate response programming (FIXED). At hospital discharge 37 patients with Thera DR pacemakers (Medtronic) were randomized either to FIXED (n = 20; 65 +/- 12 years, male n = 12) or to OPT (n = 17; 65 +/- 12 years, male n = 13). After 1 month's follow-up occurrence plaints related to rate-responsive pacing and the percentage of pacing were assessed. Other activity sensor parameters were programmed according to clinical judgement and similarly distributed in the two groups. Activity rate response was 7.1 +/- 1.4 (FIXED) and 7.2 +/- 1.7 (OPT), activity threshold was medium in 9 (FIXED) and 8 (OPT), and medium/low in 11 (FIXED) and 9 (OPT) patients, respectively. No patient with FIXED had plaints with respect to activity-triggered rate response. One patient with OPT reported palpitations due to rapid changes in the pacing rate leading to reprogramming of the pacemaker. Atrium and ventricle were paced in 56 +/- 31% (FIXED) and in 58 +/- 35% (OPT; not significant) and the atrium only in 4 +/- 10% (FIXED) and 0% (OPT; not significant), respectively. In the 17 patients programmed to OPT the pacemaker increased activity rate response in 5 and decreased activity rate response in 3 patients. In conclusion, as only 1 (3%) patient plaints related to the activity rate response and fixed rate response programming according to clinical judgement already resulting in symptom-free DDDR pacing, no differences could be detected between the fixed rate response programming and rate response optimization.

9452154

Electrocardiographic changes related to parasympathetic tone during right coronary angioplasty.

The role of basal parasympathetic tone in reducing the heart rate and causing electrocardiographic (ECG) changes during right coronary angioplasty was evaluated in 19 patients with angina pectoris. To measure parasympathetic tone, time and frequency domain parameters of heart rate variability were assessed using 24 h of ambulatory ECG data recorded before angioplasty. There was an age-dependent reduction in heart rate. However, no parameters of heart rate variability were responsible for the changes in heart rate. In contrast, the degree of ST segment elevation during angioplasty correlated significantly with the ponent of heart rate variability. Therefore, the increased parasympathetic tone, as assessed by spectral analysis, may augment the early ST segment elevation induced by right coronary occlusion.

9452155

Mortality and risk indicators for death during five years after acute myocardial infarction among patients with and without ST elevation on admission electrocardiogram.

We related observations in the electrocardiogram (ECG) on admission to hospital among consecutive patients hospitalized in one single hospital with acute myocardial infarction (AMI) and related the prognosis during the following 5 years to these observations.

9452156

Clinical significance of hypoxemia without congestive heart failure in patients presenting with acute myocardial infarction.

This study investigated the clinical significance of hypoxemia without apparent clinical congestive heart failure in patients with acute myocardial infarction (AMI). Sixty-two patients with AMI of the Killip group I and Forrester subset I state were stratified into a hypoxemia group and a normoxemia group. The increase in the neutrophil count and the severity of the coronary artery disease as graded by Gensini's score were significantly higher in the hypoxemic group. The cardiac index was lower in hypoxemic than normoxemic patients. Myocardial scintigraphy revealed no acute difference in defect scores (DS) or left ventricular ejection fraction (LVEF) between the two groups, but DS was significantly higher (p < 0.01) and LVEF was lower (p < 0.01) in the hypoxemic group 2 years after infarction. Patients with hypoxemia have a more severe angiographic coronary pathology than normoxemic patients, and latent cardiac hypofunction occurs.

9452157

Symptom-oriented nitrate administration and survival after acute myocardial infarction. Israeli Thrombolytic Survey Group.

The effect of nitrates during evolving myocardial infarction is controversial. While previous studies showed that nitrates improve left ventricular function and have a beneficial effect on survival, two recent randomized megatrials showed that nitrates did not alter mortality after acute myocardial infarction (AMI). The present study analyzes the use of nitrates in clinical practice and their impact on mortality in a cohort of unselected consecutive AMI patients admitted to all 25 coronary care units operating in Israel during 2 months in 1994. Among 966 patients in Killip class I-III on admission, 81% (n = 783) received nitrate therapy by intravenous infusion or orally. Baseline characteristics of patients treated with or without nitrates were quite similar. Seven-day mortality was markedly reduced in the nitrate-treated group (5 and 11 %, p < 0.001) parison with those who did not receive nitrates. After adjustment for pertinent variables the 7-day relative risk (RR) of mortality was 0.51 [95% confidence interval (CI) 0.25-1.07; p = 0.08], whereas, the 7-day to 1-year mortality after AMI was not altered by nitrate use (RR = 0.97; 95% CI 0.56-1.68; p = 0.92). Nitrate therapy remains a widespread and a valid symptom-oriented therapeutic approach, especially early after AMI, in munity.

9452158

Assessment of the coronary artery disease and systolic dysfunction in hypertensive patients with the dobutamine-atropine stress echocardiography: effect of the left ventricular hypertrophy.

This study was performed to evaluate whether left ventricular hypertrophy (LVH) can influence the diagnostic accuracy of coronary artery disease (CAD) using the dobutamine stress echocardiography (DSE) in hypertensive patients. In addition to the detection of CAD, the relationship between systolic dysfunction and the quantitation wall motion scoring system of DSE was studied also. DSE was performed in 101 patients. There were 45 (45%) patients with a history of acute myocardial infarction. Twenty-eight patients (28%) had electrocardiographic LVH and 59 patients (58%) had echocardiographic LVH. A total of 74 patients (73%) had angiographically documented CAD defined as > or = 50% diameter stenosis. For the 56 patients without history of myocardial infarction, the diagnostic sensitivity, specificity, and accuracy in detecting CAD were not influenced by LVH defined by either electrocardiography or echocardiography. For the total patients, the diagnostic sensitivity, specificity, and accuracy in detecting multivessel disease were also not influenced by LVH defined by either method. The resting global wall motion score was correlated well with the left ventricular ejection fraction in patients with and without LVH (r = -0.70, p < 0.001 vs. r = -0.70, p < 0.001). When using the resting wall motion score of 24 as a cutoff value, the diagnostic sensitivity, specificity, and accuracy of systolic dysfunction (defined by left ventricular ejection fraction <40%) were 79, 86 and 85%, respectively. In conclusion, the diagnostic accuracy of CAD using the DSE was not affected by LVH in hypertensive patients. In addition to detection of coronary artery disease, the resting wall motion score of DSE was able to detect systolic dysfunction in patients with and without LVH.

9452159

Relationship of some risk factors with typical and atypical manifestations of coronary heart disease.

This analysis explores whether 'typical' clinical manifestations of coronary heart disease (CHD) such as myocardial infarction and sudden death, relate to major cardiovascular risk factors in the same way as the 'atypical' manifestations, e.g. heart failure and chronic arrhythmias.

9452160

Diastolic time during weight carrying exercise in patients with myocardial infarction.

Cardiovascular responses to static-dynamic exercises were studied in 27 patients with recent myocardial infarction. Patients with ischemic electrocardiographic changes at peak weight carrying exercise (group 1 = 8 patients) had a significantly larger left ventricular end-diastolic volume than those without (group 2 = 19 patients). A higher tension time index and shortening of diastolic time/min was observed in group pared to group 2 during weight carrying. Thus, in addition to the increased myocardial oxygen demand, shortening of the diastolic perfusion time was observed during static-dynamic exercise in patients with dilated heart after myocardial infarction.

9452161

Electrophysiological evidence of reinnervation of the transplanted human heart.

Beat-by-beat heart rate (HR) changes during exercise were studied in two young and fit heart-transplanted humans at different time intervals following transplantation. Upon the start of the exercise, a slow gradual increase in HR was seen during the early experiments after the transplantation, whereas an immediate rapid increase in HR was observed during the later experiments. From standard ECGs obtained 32 months after transplantation, two P waves at somewhat different rates could be identified in both subjects, probably arising from donor and recipient sinoatrial nodes, respectively. The two P wave rate changes during and following exercise were very similar. We conclude that these changes in the HR pattern and ECG must be due to reinnervation of the donor hearts, most likely by parasympathetic cardiac fibers.

9452162

Ergonovine-testing-directed therapy and long-term outcome of sudden-death survivors with no apparent heart disease.

Coronary artery vasospasm, the mon cause of sudden death in patients with structurally normal hearts, is not well recognized. We describe 2 survivors of sudden death with ergonovine-inducible coronary artery vasospasm successfully treated long term with calcium channel blockers. Of the reported (17 worldwide) patients with documented vasospasm-mediated sudden cardiac death treated with calcium blockers, none have had a recurrent event. This is substantially less than the 6-month sudden-death rate of 18 % of untreated vasospasm. We advocate that ergonovine provocative testing of sudden-death survivors with structurally normal hearts, followed by appropriate therapy with calcium channel blockers, be the standard approach for these highly treatable patients.

9452163

Validity, reliability and utility of the chronic mild stress model of depression: a 10-year review and evaluation.

This paper evaluates the validity, reliability and utility of the chronic mild stress (CMS) model of depression. In the CMS model, rats or mice are exposed sequentially, over a period of weeks, to a variety of mild stressors, and the measure monly used to track the effects is a decrease in consumption of a palatable sweet solution. The model has good predictive validity (behavioural changes are reversed by chronic treatment with a wide variety of antidepressants), face validity (almost all demonstrable symptoms of depression have been demonstrated), and construct validity (CMS causes a generalized decrease in responsiveness to parable to anhedonia, the core symptom of the melancholic subtype of major depressive disorder). Overall, the CMS procedure appears to be at least as valid as any other animal model of depression. The procedure does, however, have two major drawbacks. One is the practical difficulty of carrying out CMS experiments, which are labour intensive, demanding of space, and of long duration. The other is that, while the procedure operates reliably in many laboratories, it can be difficult to establish, for reasons which remain unclear. However, once established, the CMS model can be used to study problems that are extremely difficult to address by other means.

9452180

BIMT 17: a putative antidepressant with a fast onset of action?

BIMT 17, the pound reported to be a full 5-HT1A agonist and a 5-HT2A antagonist at the frontal cortex, was assessed in three animal paradigms sensitive to antidepressants in rats: olfactory bulbectomy (OB), differential-reinforcement-of-low rate 72-s (DRL 72-s) and learned helplessness (LH). In the OB rats, BIMT 17, given once daily for 14 consecutive days at an i.p. dose of 10 mg/kg, but not of 20 mg/kg, reduced the increase in ambulation of OB rats, 24 h after the last administration. In the DRL 72-s test, BIMT 17 had a different profile than imipramine. A single i.p. injection of 5, 10, 15 or 20 mg/kg BIMT 17, in contrast to the same doses of imipramine, did not affect response and reinforcement rate in DRL 72-s 1 h after the administration. On the other hand, BIMT 17 slightly shifted the peak of the interresponse time (IRT) distribution towards shorter IRT duration, while imipramine shifted the peak of the IRT distribution towards longer IRT duration. In the LH test, acute oral doses (36, 48 or 60 mg/kg) of BIMT 17, given 30 min before testing, reduced the number of escape failures in LH without altering the intertrial crossings. This effect was also induced by a repeated, but not single, administration with 8 or 16 mg/kg imipramine. The plasma levels following i.p. 10 or oral 48 mg/kg BIMT 17 were in the same range. These results indicate that BIMT 17 does not behave like imipramine in all the tests, and suggest that BIMT 17 acts through different mechanisms of action than imipramine. Only clinical trials will tell whether these mechanisms will be relevant, but if so, BIMT 17 might induce a faster onset of therapeutic activity.

9452181

Individual differences in response to imipramine in the mouse tail suspension test.

The tail suspension test is a behavioural primary screen for detecting potential antidepressant drugs. In this test, a reduction of duration of immobility after treatment with imipramine is obtained in mice of the NMRI strain but not of the CD1 strain. The present experiments evidence important differences between individuals of the latter strain in both the amount of immobility observed in naive mice and the effects of three antidepressants. The reproducibility of the tail suspension-induced behavioural despair was high in individual CD1 male mice and allowed a preselection of spontaneous high and low immobility scorers. Only the high immobility scorers were responsive to imipramine (30 mg/kg), desipramine (30 mg/kg) and paroxetine (10 mg/kg). The percentage of spontaneous high immobility scorers was higher in NMRI (50%) than in CD1 (20%) mice, justifying the use of the former strain for screening potential antidepressants. However, controlling for individual differences in the spontaneous performance in this animal model of depression may provide a useful tool to study behavioural, neurochemical and neuroendocrine correlates of antidepressant action.

9452182

8-OH-DPAT in the median raphe, dorsal periaqueductal gray and corticomedial amygdala nucleus decreases, but in the medial septal area it can increase maternal aggressive behavior in rats.

The purpose of the present study was to analyze the role of somatodendritic autoreceptors and postsynaptic 5-HT1A receptors in the modulation of maternal aggressive behavior. The 5-HT1A receptor agonist 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin) was microinjected (0.2, 0.5 and 2.0 microg/0.2 microl) in different brain areas of female Wistar rats: median raphe nucleus (MnR); medial septal area (MS); anterior edial amygdaloid nucleus (ACoM); and dorsal periaqueductal gray (DPAG). The behaviors of lactating female rats with pups against a conspecific male intruder were recorded on day 7 post-partum. Results showed that in the median raphe nuclei, in the dorsal periaqueductal gray and in the edial amygdaloid nucleus 8-OH-DPAT decreased maternal aggression; while in the medial septum, the intermediate dose (0.5 microg/0.2 microl) of the 5-HT1A receptor agonist increased the aggressive behavior of the lactating female rat. It is concluded that the main role of the 5-HT1A somatodendritic autoreceptors and the post-synaptic receptors of the brain areas studied is to decrease maternal aggression, however, at a specific dosage, 8-OH-DPAT acting on postsynaptic receptors of the medial septal area can increase aggressiveness.

9452183

Effects of imipramine on raphe nuclei and prefrontal cortex extracellular serotonin levels in the rat.

The effect of acute administrations of three doses of imipramine (1, 5 and 10 mg/kg s.c.), a widely used tricyclic antidepressant, on extracellular levels of serotonin (5-HT) has been studied by intracerebral microdialysis in raphe nuclei and prefrontal cortex of conscious rats. Imipramine 1 mg/kg s.c. did not change extracellular 5-HT in either raphe nuclei and prefrontal cortex. However, with the dose of 5 mg/kg s.c. imipramine induced in raphe nuclei, a brief increase of extracellular 5-HT followed by a lowering (55-65% basal release) of the neurotransmitter. The same dose of imipramine decreased (60-70% of basal value) extracellular 5-HT in prefrontal cortex. Imipramine 10 mg/kg s.c. significantly increased 5-HT levels in both raphe nuclei (190 +/- 20% above basal value) and prefrontal cortex (280 +/- 15% above basal value). Pretreatment with (-)pindolol (5 mg/kg s.c.), a non-selective 5-HT1A subtype receptor antagonist, 30 min before imipramine 5 mg/kg, modified the effect of the antidepressant: an increase, instead of a decrease, on prefrontal cortex dialysate 5-HT was observed. (-)Pindolol (10 mg/kg s.c.) increased extracellular 5-HT in both raphe nuclei (155 +/- 20% above basal value) and prefrontal cortex (160 +/- 8% above basal value). These data show that acute administration of imipramine modifies extracellular 5-HT at the level of the raphe nuclei and prefrontal cortex. 5-HT1A autoreceptors in the raphe nuclei, which this study suggests to be tonically active, may be stimulated after systemic administration of high doses of imipramine.

9452184

Do noradrenergic reuptake inhibitors affect serotonergic function in depression?

d-Fenfluramine, a specific 5-HT releasing agent without the catecholamine effects of d,l-fenfluramine, was used as a serotonergic neuroendocrine challenge in subjects with unipolar major depression. Prolactin and cortisol responses to 30 mg d-fenfluramine were measured in patients at baseline. Patients were then randomly assigned to treatment for 6 weeks with a specific noradrenergic reuptake inhibitor, a tricyclic antidepressant, or placebo. Response to antidepressant treatment was assessed, and patients underwent further testing with d-fenfluramine. Prolactin responses were increased by treatment, but this was independent of whether or not patients' depression responded to treatment. Seven patients were treated with a specific noradrenergic reuptake inhibitor. These patients showed a significant rise in 5-HT-mediated cortisol responses after treatment, independent of whether their depression improved. We conclude that antidepressants which selectively modify noradrenergic function also have effects on 5-HT function as measured by neuroendocrine testing.

9452185

Reciprocal regional changes in brain NPY receptor density during dietary restriction and dietary-induced obesity in the rat.

Neuropeptide Y (NPY) potently induces feeding, reduces thermogenesis and induces obesity in rats when injected into the cerebral ventricles. Groups of male Wistar rats were either restricted to 60% of their normal daily food intake over 10 days or made obese by presenting them with a high-calorie diet rich in sugars and fat over 6 weeks. Food restricted rats lost up to 20% of their body pared with control rats and had large reductions in their body fat mass. By contrast, rats with dietary-induced obesity weighed 26% more than controls due mainly to increased body fat mass. Quantitative receptor autoradiography demonstrated reduced [(125)I]PYY binding in the hypothalamic lateral (perifornical) and dorsal areas, hypothalamic ventromedial, arcuate and dorsomedial nuclei, hippocampal CA3 region, centromedial amygdaloid nucleus and thalamic paraventricular and reuniens nuclei in dietary restricted pared with controls. By contrast, regional [(125)I]PYY binding was significantly increased in hypothalamic lateral and dorsal areas, hypothalamic arcuate and dorsomedial nuclei, amygdaloid medial and centromedial nuclei, thalamic centromedial and paraventricular nuclei of dietary obese rats versus controls. Masking NPY Y1 receptors with 1 microM BIBP3226, a selective Y1 receptor antagonist, revealed that the changes in [(125)I]PYY binding in brains of food-restricted and dietary-obese rats were due to changes in BIBP3226-insensitive binding sites, presumably Y2 or Y5 NPY receptors. These data suggest that dietary-restriction stimulates NPY release resulting in down-regulation of NPY Y5 'feeding' and/or Y2 receptors and reduced BAT thermogenesis thereby providing an increased drive to eat to restore normal caloric intake whilst reducing thermogenesis in order to conserve fat reserves. By contrast, the up-regulation of NPY Y5 and/or Y2 receptors in dietary-induced obesity is consistent with inhibition of NPY release in the hypothalamus, amygdala and thalamus. Overall, we suggest that there is a regional increase in NPY release during negative energy balance, such as during food-restriction and a reduced regional release of NPY in positive energy balance, such as during hyperphagia associated with the development of obesity.

9452186

Expression and induction of cytochrome P-450 1A1 and P-450 2D subfamily in the rat glioma C6 cell line.

The cytochrome P-450 (P-450) monooxygenase system can catalyze the oxidation of a wide variety of endogenous and pounds, including steroid hormones, fatty acids, drugs and pollutants. The functions of this system are as diverse as the substrates. Though this enzyme system has the highest level of activity in the liver, it is present in other tissues, including brain. In this study, we have established the rat glioma C6 cell line as an in vitro model system to examine the expression and induction of P-450 1A1 and the P-450 2D subfamily. Rat glioma C6 cells were treated with P-450 inducers phenobarbital (PB) or benzo[a]anthracene (BA). The presence of P-450 1A1 and 2D1-5 was detected by reverse transcription followed by polymerase chain reaction (RT-PCR) and confirmed by restriction enzyme digestion. The induction of P-450 1A1 and 2D1-5 was quantified petitive PCR. Although P-450 2D1-5 do not seem to be affected by PB or BA treatment, tenfold induction of P-450 1A1 mRNA after BA treatment was detected. Western blot analysis of microsomal preparations of glioma C6 cells demonstrated the presence of P-450 1A1 at the protein level. ELISAs showed that BA induces P-450 1A1 proteins 7.3-fold. These experiments provide further evidence that the rat glioma C6 cell line contains an active cytochrome P-450 monooxygenase system which can be induced by P-450 inducers. In summary, we believe the presence of the cytochrome P-450 monooxygenase system in glial cells of the brain may be important in chemotherapy and carcinogenesis of brain tumors.

9452187

Insulin-like growth factor-I prevents development of a vincristine neuropathy in mice.

Vincristine is monly used antitumor agent whose major dose-limiting side-effect is a mixed sensorimotor neuropathy. To assess whether insulin-like growth factor-I (IGF-I), a neurotrophic agent that supports the survival of motoneurons and enhances regeneration of motor and sensory neurons, could prevent the peripheral neuropathy produced by vincristine, mice were treated with both vincristine (1.7 mg/kg, i.p., 2 x /week) and/or IGF-I (0.3 or 1 mg/kg, s.c. daily) for 10 weeks. In mice treated with vincristine alone, there was evidence of a mixed sensorimotor neuropathy as indicated by changes in behavior, nerve conduction and histology. Caudal nerve conduction velocity was significantly slower in mice treated with vincristine alone pared with vehicle-treated mice. Vincristine treatment alone also significantly increased hot-plate latencies and reduced gait support and stride length, but not toe spread distances. The effects of vincristine were panied by degeneration of sciatic nerve fibers and demyelination, indicating a peripheral neuropathy. IGF-I (1 mg/kg, s.c.) administered to vincristine-treated mice prevented the neurotoxic effects of vincristine as measured by nerve conduction, gait, response to noxious stimuli and nerve histology. At a lower dose of 0.3 mg/kg administered s.c., IGF-I partially ameliorated the neuropathy induced by vincristine as this dose only prevented the change in nerve conduction and hot-plate latencies. IGF-I administered alone had no effect on any of these parameters. These results suggest that IGF-I prevents both motor and ponents of vincristine neuropathy and may be useful clinically in preventing the neuropathy induced by vincristine treatment.

9452188

Locus coeruleus electrophysiological activity and responsivity to corticotropin-releasing factor in inbred hypertensive and normotensive rats.

The spontaneously hypertensive rat (SHR) and its normotensive progenitor, the Wistar-Kyoto rat (WKY), have been shown to be differentially responsive to the behavioral and endocrine effects of both stress and corticotropin-releasing factor (CRF), both of which increase locus coeruleus (LC) electrophysiological activity. However, the effect of central administration of CRF in these rat strains has yet to be examined. In the present studies, LC electrophysiological responsivity to intracerebroventricular infusions of CRF was assessed in SHR, an inbred strain of WKY rats (the WKY[LJ] rat), and an outbred normotensive rat strain, Sprague-Dawley (SD) rats. Spontaneous LC discharge rate, mean arterial blood pressure and heart rate were also examined. LC activity was increased to the same extent in the three rat strains in response to a 3 microg dose of CRF. However, WKY(LJ) rats showed an exaggerated LC in response to a 1 microg dose of CRF parison to the other rat strains tested at this dose. Spontaneous discharge rates of individual LC neurons were lower in both SHR and WKY[LJ] rats than in SD rats. Further, the variability of the discharge rates of LC neurons was greater in WKY[LJ] rats than in the other two strains. These results indicate that the WKY[LJ] rat may provide a useful model for assessing the role of sensitivity to CRF in stress responsiveness.

9452189

The progression of beta-amyloid deposition in the frontal cortex of the aged canine.

Brains from 41 aged canines (> or = 10 years of age) were examined immunohistochemically to characterize the laminar distribution and age-related progression of beta-amyloid (A beta) in frontal cortex. We classified the A beta patterns into four distinct types. Type I was characterized by small, faint deposits of A beta in deep cortical layers. Type II consisted of diffuse deposits of A beta mainly in layers V and VI. Type III had both dense plaques in superficial layers, and diffuse deposits in deep layers. Finally, Type IV had solely dense plaques throughout all layers of cortex. pared the A beta distribution pattern between the Old canines (10-15 years, n = 22) and the Very Old canines (> 15 years, n = 19). The Old group primarily had negative staining, or Type I and Type II patterns of amyloid deposition (73%). Conversely, the Very Old group had predominantly Types II, III and IV deposits (89.5%), a difference that was significant (P < 0.05). We suggest that A beta deposition in canine frontal cortex is a progressive age-related process beginning with diffuse deposits in the deep cortical layers followed by the development of deposits in outer layers. In support of this hypothesis, the deeper layer diffuse plaques in the Very Old group of dogs also contain the largest proportion of beta-amyloid with an isomerized aspartic acid residue at position 7, indicating that these deposits had been present for some time. We also observed fiber-like A beta immunoreactivity within regions of diffuse A beta deposits. These fibers appeared to be degenerating neurites, which were negative for hyperphosphorylated tau. Therefore, these fibers may represent a very early form of neuritic change that precede tau hyperphosphorylation or develop by an alternative pathway.