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Biomedical subjects

J W Allen

Publications and source records attributed to J W Allen.

At least 109 records · Page 6Linked to original sources
PubMed1994

Endothelium-dependent regulation of coronary tone in the neonatal pig.

We examined the effects of endothelium-dependent responses on coronary perfusion pressure (CPP) in isolated, blood-perfused neonatal pig hearts under conditions of controlled coronary flow. Baseline CPP was increased 8%-21% by the cyclooxygenase inhibitor indomethacin (10-100 microM), and 30%-92% by NG-monomethyl-L-arginine (L-NMMA, 10-100 microM), an inhibitor of nitric oxide (NO) synthase, suggesting that both prostaglandin and nitric oxide synthesis contribute to basal coronary tone. Both acetylcholine (ACh) and bradykinin (BK) decreased CPP. These effects were enhanced by preconstriction with endothelin-1. L-NMMA markedly attenuated BK-induced coronary vasodilation and converted the ACh response to constriction, indicating a significant role for NO release in these responses. After 1 h of total, global normothermic ischemia and 45 min of reperfusion, vasoconstrictor responses to endothelin-1 and ACh were enhanced, while BK-induced dilation was significantly reduced. L-Arginine supplementation during reperfusion did not restore vasodilatory responses to ACh or BK. The magnitude of L-NMMA-induced coronary vasoconstriction during reperfusion was similar to that observed without ischemia-reperfusion. Coronary vasodilation in response to sodium nitroprusside, a NO precursor that causes endothelium-independent vasodilation by directly activating smooth muscle guanylate cyclase, was unaffected by ischemia-reperfusion. We conclude that NO production in the neonatal coronary circulation contributes to both basal tone and the response to ACh and BK. After ischemia-reperfusion, basal NO production and smooth muscle relaxation mediated by guanylate cyclase are intact, whereas agonist-stimulated dilation is significantly impaired.

Acetylcholine↗
PubMed1993

Species identification and chemical analysis of psychoactive fungi in the Hawaiian islands.

Several fungi species collected in the Hawaiian Islands have been reported to be psychoactive. Previous chemical analyses together with the present study indicate that 5 coprophilous and one non-coprophilous species occurring in the islands are now known to contain psychoactive alkaloids. At least some of these species are consumed in the Hawaiian Islands, as well as elsewhere, for non-traditional, recreational purposes. These include Copelandia cyanescens (Berk. et Br.) Singer, Copelandia tropicalis (Ola'h) Singer and Weeks (syn. Panaeolus tropicalis Ola'h), Copelandia anomala Murrill, and Panaeolus subbalteatus (Berk. and Br.) Sacc., which have already been described from the Hawaiian Islands. Three more mind-altering fungi and one non-psychoactive species are reported from this archipelago for the first time. These psychoactive fungi include Copelandia bispora (Malençon et Bertault) Singer and Weeks from O'ahu, Copelandia cambodginiensis (Ola'h et Heim) Singer and Weeks from O'ahu, and Amanita muscaria (L.) Hooker from Kaua'i. Panaeolus goossensiae Beeli identified from O'ahu contains tryptamine compounds; however, the psychoactive alkaloids psilocybin and psilocin were not found in this dung species.

Animals↗
PubMed1993

Cytogenetic studies of rodents exposed to styrene by inhalation.

Female B6C3F1 mice and Fischer 344 rats were exposed to styrene at nominal concentrations of 125, 250 and 500 ppm by inhalation for 6 h per day for 14 consecutive days. One day after the final exposure, murine peripheral blood lymphocytes, spleen and lungs were removed, and the cells were cultured for analysis of chromosomal aberrations, micronucleus induction (using the cytochalasin B-block method) and sister chromatid exchange. Peripheral blood smears were scored for micronucleus induction in normochromatic erythrocytes. For the rats, peripheral blood lymphocytes were cultured for analyses of sister chromatid exchange, chromosomal aberrations and micronuclei in cytochalasin B-induced binucleated cells and were also examined in the single-cell gel assay for analysis of DNA strand breakage under alkaline conditions. Bone-marrow smears were made from femurs of rats for analysis of micronucleus induction in normochromatic erythrocytes. Small but statistically significant concentration-related increases in the frequency of sister chromatid exchange were seen in both mice and rats in all cell types examined. No statistically significant concentration-related increase in chromosomal aberration or micronucleus induction frequencies were observed in either species, and there was no significant increase in DNA strand breakage in peripheral blood lymphocytes from exposed rats. These results indicate that styrene is a weak inducer of sister chromatid exchange in vivo when administration to rodents by inhalation.

Administration, Inhalation↗
PubMed1992

Percutaneous closure of a secundum atrial septal defect and double balloon valvotomies of a severe mitral and aortic valve stenosis in a patient with Lutembacher's syndrome and severe pulmonary hypertension.

This is a 43-yr-old female presenting with recurrent atrial septal defect, closed surgically, 10 years prior, severe aortic and mitral stenosis, and severe tricuspid regurgitation. She was considered inoperable because of the severe pulmonary hypertension and the complexity of the disease. A percutaneous umbrella closure of the atrial septal defect in conjunction with mitral and aortic balloon valvotomies could be safely and successfully performed. After significant clinical and hemodynamic improvement, surgery was judged feasible, but was refused by the patient who suddenly expired 8 weeks later. The usefulness of percutaneous therapy as a rescue procedure and the management of patients with Eisenmenger's physiology are discussed.

Adult↗
PubMed1992

Comparison of Inoue single-balloon versus double-balloon technique for percutaneous mitral valvotomy.

The results of percutaneous mitral valvotomy by means of the Inoue single-balloon (N = 85, group 1) and the double-balloon (N = 322, group 2) techniques were compared in a nonrandomized study. The groups were not significantly different with regard to age, sex, calcification, or hemodynamic values before percutaneous mitral valvotomy. After percutaneous mitral valvotomy, patients in both groups had significant hemodynamic and clinical improvement. The increases in mitral valve area and cardiac output and the decreases in mitral valve gradient, mean pulmonary artery pressure, and mean left atrial pressure were greater in group 2. Mitral valve area determined by the Gorlin method increased 191% in group 2 and 106% in group 1; Doppler-determined mitral valve area increased 133% in group 2 and 98% in group 1. Optimal results were achieved in 93% of the patients in group 2 and 76% in group 1 (p less than or equal to 0.0001). In group 1, 6% of patients had a left-to-right shunt as shown by angiography versus 14% in group 2 (p less than or equal to 0.05). In group 2, 46% of patients had at least a 1+ increase in mitral regurgitation versus 52% in group 1. Among the patients who had an increase in mitral regurgitation, 36% of those in group 1 versus 9% in group 2 had a 2+ or more increase (p less than or equal to 0.001). The mean balloon diameter to anulus ratio was larger in group 2, and the larger the balloon diameter to anulus ratio, the greater the increase in mitral valve area.(ABSTRACT TRUNCATED AT 250 WORDS)

Catheterization↗
PubMed1992

Micronuclei and other nuclear anomalies in buccal smears: methods development.

Laboratory work aimed at improving the epidemiologic utility of an innovative genotoxicity assay is described. The exfoliated cell micronucleus assay involves microscopic analysis of epithelial smears to determine the prevalence of micronucleation, an indicator of structural or numerical chromosome aberrations. While the assay holds promise for the study of epithelial carcinogens, it is hampered by the fact that exfoliated cells are moribund and undergo degenerative phenomena that can produce extranuclear objects difficult to distinguish from classical micronuclei. Modifications in the protocol were assessed in sample buccal smears from several study populations: radiotherapy patients, nonusers of tobacco, and snuff users. Refinements in micronucleus scoring criteria and the inclusion of other nuclear anomalies in the scoring system are proposed. We demonstrate that our criteria are successful in detecting excess micronucleation in positive controls. We also provide evidence that other nuclear anomalies are at least as common as micronucleation and that therefore there is the potential for extensive misclassification. Reliability was assessed in duplicate readings.

Cell Nucleus↗
PubMed1992

Cytogenetic studies of mice exposed to styrene by inhalation.

The data for the in vivo genotoxicity of styrene (STY) are equivocal. To evaluate the clastogenicity and sister-chromatid exchange (SCE)-inducing potential of STY in vivo under carefully controlled conditions, B6C3F1 female mice were exposed by inhalation for 6 h/day for 14 consecutive days to either 0, 125, 250 or 500 ppm STY. One day after the final exposure, peripheral blood, spleen, and lungs were removed and cells were cultured for the analysis of micronucleus (MN) induction using the cytochalasin B-block method, chromosome breakage, and SCE induction. Peripheral blood smears were also made for scoring MN in erythrocytes. There was a significant concentration-related elevation of SCE frequency in lymphocytes from the spleen and the peripheral blood as well as in cells from the lung. However, no statistically significant concentration-related increases were found in the frequency of chromosome aberrations in the cultured splenocytes or lung cells, and no significant increases in MN frequencies were observed in binucleated splenocytes or normochromatic erythrocytes in peripheral blood smears.

Administration, Inhalation↗
PubMed1992

Kinetochore-staining of spermatid micronuclei: studies of mice treated with X-radiation or acrylamide.

The rodent spermatid micronucleus (MN) assay was used in conjunction with immunofluorescent techniques to distinguish kinetochores in MN following exposure of mice to X-radiation or acrylamide. After either treatment, modest increases in kinetochore-positive MN were observed. Spermatids which had been exposed during meiotic prophase to X-rays (400 cGy) had approximately 10-fold increases in MN compared to controls; up to 15% of the MN observed were kinetochore-positive. Following acrylamide treatment of meiotic prophase cells, there was a doubling of spermatid MN over baseline levels, approximately one-third of which were kinetochore-positive.

Acrylamide↗
PubMed1992

Psychoactive mushroom use in Koh Samui and Koh Pha-Ngan, Thailand.

This paper presents the results of recent ethnomycological exploration in southern Thailand. Field observations, interviews and collection of fungi specimens were carried out primarily on two islands, Koh Samui and Koh Pha-ngan, situated in the western region of the Gulf of Siam. Some fieldwork was also conducted in the northern Thai province of Chiang Dao and in the southern Thai province of Surat Thani. During five separate excursions (1989-90), observations were made of occurrence, harvesting, use, and marketing of psychoactive fungi by local Thai natives (males and females, adults and children), foreign tourists, and German immigrants. The first records of psychoactive Psilocybe subcubensis and Copelandia dung fungi in Thailand are presented in this paper. These fungi exhibited intense bluing reactions when handled, indicating the presence of psilocybin and/or psilocin. Seven collections of Psilocybe cubensis (Earle) Singer and/or Psilocybe subcubensis Guzman and four collections of Copelandia sp. were harvested and sun-dried for herbarium deposit. These fungi are cultivated or occur spontaneously, often appearing in the decomposed manure of domesticated water buffalo (Bubalus bubalis) and at least three different species of cattle (Bos indicus, B. guarus, and B. sundaicus). The psychoactive fungi are cultivated in clandestine plots, both indoors and outdoors, in the uplands and villages on Koh Samui by both Thai natives and some foreigners. The sale of psychoactive fungi directly to tourists and to resort restaurants for use in edible food items such as omelettes and soups is discussed in detail. The preparation and sale of mushroom omelettes adulterated with artificial hallucinogens in some restaurants is also discussed. In addition, the marketing of items such as hand painted T-shirts, post cards, and posters bearing mushroom related motifs in Thailand is described.

Animals↗
PubMed1992

An audit of preschool vision screening.

An audit was carried out to clarify the dispute surrounding the vision screening test at 3.5 years. The uptake was 53.5%, sensitivity 77%, specificity 96%, and positive predictive value 50%. In particular the uptake was poor and the test needed a clear policy for the future.

Child, Preschool↗
PubMed1992

Serological titers to bovine herpesvirus 1, bovine viral diarrhea virus, parainfluenza 3 virus, bovine respiratory syncytial virus and Pasteurella haemolytica in feedlot calves with respiratory disease: associations with bacteriological and pulmonary cytological variables.

Acute and convalescent serum samples were taken from 59 calves with signs of respiratory disease (cases) and 60 clinically normal animals (controls) during their first month in the feedlot. Sera were analyzed for antibodies to bovine parainfluenza 3 (PI3) virus by hemagglutination inhibition, to bovine viral diarrhea (BVD) virus, bovine respiratory syncytial (BRS) virus and bovine herpesvirus 1 (BHV1) by virus neutralization, and to Pasteurella haemolytica by indirect agglutination (PhIA) and cytotoxin neutralization (PhCN) tests. There was minimal evidence of serological activity to BHV1. Serological activity to the other agents occurred commonly and the prevalence of acute titers and their mean values was similar in case and control groups. Mean convalescent PI3 and P. haemolytica (PhIA) titers were higher in controls than cases (p < 0.01) but, otherwise, convalescent titers did not differ between groups. The incidence of seroconversion was similar in both groups for all agents except for PI3 virus which was more frequent in controls than cases (p < 0.0001). There was a positive association between PhIA and CN seroconversion and isolation of P. haemolytica from bronchoalveolar lavage (BAL) fluid (p < 0.1). The measure of agreement (kappa) between seroconversion with the P. haemolytica PhIA and PhCN tests was 0.51. Bacteriological and cytological evaluations of the respiratory tract were made using BAL. No associations were evident between serological titers and pulmonary cytology. A multivariate logistic analysis was used to evaluate associations between disease status and serological, bacteriological and cytological data. Cases were positively associated with the presence of neutrophils and Pasteurella multocida in BAL fluid and negatively associated with PI3 virus and PhIA seroconversion.

Acute Disease↗
PubMed1992

Changes in the bacterial flora of the upper and lower respiratory tracts and bronchoalveolar lavage differential cell counts in feedlot calves treated for respiratory diseases.

Serial nasopharyngeal swab and bronchoalveolar lavage cultures were used to estimate changes in the bacterial flora of the respiratory tracts of calves during the first month after arrival in the feedlot. Bronchoalveolar lavage (BAL) differential cell counts served to evaluate pulmonary inflammatory changes during this period. Two groups of calves were studied, one consisting of clinically normal controls (n = 60), the other, of cases (n = 59) which received treatment for respiratory disease (penicillin +/- trimethoprimsulfadoxine). A variety of organisms, including Pasteurella multocida, Pasteurella haemolytica, Haemophilus somnus, Mycoplasma bovis and Mycoplasma bovirhinis, were present in the upper and lower airways of both groups during the postarrival period. With the exception of M. bovis, an overall decline in the prevalence of these organisms was observed during the course of the study. In cases, there was a marked decrease in the number of Pasteurella spp. and H. somnus isolates immediately following treatment. For the Pasteurella spp., however, this effect was shortlived as they often appeared to recolonize the respiratory tract within eight days of terminating antimicrobial therapy. Treatment did not appear to affect the frequency of isolating M. bovis. Its prevalence, in both groups of calves, increased to levels approaching 100% during the course of the study. All Pasteurella spp. isolates were tested for susceptibility to several commonly used antimicrobials. Resistance was only evident among P. haemolytica isolated from cases and in every instance this was to a combination of penicillin, ampicillin and tetracycline. Significantly more isolates were resistant after treatment than before. There were BAL differential cell count abnormalities indicative of inflammation in both cases and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Cytological findings in bronchoalveolar lavage fluid from feedlot calves: associations with pulmonary microbial flora.

Samples obtained by bronchoalveolar lavage (BAL) were used to evaluate pulmonary cytology in 59 feedlot calves with clinical signs of respiratory disease (cases) and 60 clinically normal comparison calves (controls). Many calves in both case and control groups had inflammatory changes in the lower respiratory tract, as determined by changes in proportions in the BAL differential cell count. Approximately 35% of cases and 40% of controls showed a normal differential cell count. It therefore appeared that the criteria used to select cases for treatment, which were similar to those often used in the field, were poor predictors of lower respiratory tract disease. A positive association was found between an increased proportion of neutrophils in BAL fluid and isolations of Pasteurella multocida and Mycoplasma bovis from BAL fluid.

Animals↗
PubMed1991

Micronuclei and other nuclear anomalies in buccal smears: a field test in snuff users.

A revised protocol for the exfoliated cell micronucleus assay was field-tested in a population exposed to a genotoxic agent, snuff, at levels associated with a significant increase in cancer risk. The standard assay involves examination of epithelial smears to determine the prevalence of micronucleated cells, an indication of chromosome breakage or mitotic interference. The assay was revised to increase specificity and to include separate scoring of other nuclear anomalies associated with cytotoxicity and genotoxicity. The modified assay was applied to buccal smears of 38 female snuff users and 15 female nonusers recruited from a North Carolina clinic in 1987. The prevalence of micronucleation was elevated in the snuff users as compared with the nonusers (prevalence ratio = 2.4, 95% confidence interval 1.1-5.2) and, to a lesser extent, at the usual contact site as compared with a distal buccal site in the snuff users (prevalence ratio = 1.5, 95% confidence interval 0.9-2.5). The pattern of relative frequencies of several nuclear anomalies provided strong evidence of a cytotoxic effect, the prevalence ratios ranging from 2 to 13. Nuclear degenerative phenomena can be difficult to distinguish from classical micronuclei; thus, the observed association of indicators of cytotoxicity with exposure introduces the possibility of bias away from the null in micronucleus findings due to differential misclassification. Until methods to better distinguish extranuclear bodies of different origins become available, investigators should use the revised protocol and should focus on agents not thought to be cytotoxic.

Adult↗
PubMed1991

Evidence that methanol inhalation does not induce chromosome damage in mice.

Mice were exposed by inhalation to 800 or 4000 ppm methanol for 5 days, and cytogenetic effects were analyzed in blood erythrocytes, lung cells, and testicular germ cells. The results were uniformly negative; no increased frequencies of micronuclei in blood cells, of sister-chromatid exchanges, chromosome aberrations, or micronuclei in lung cells, or of synaptonemal complex damage in spermatocytes were found. From the standpoint of risk assessment, these experimental studies do not reveal any evidence of a cytogenetic hazard associated with inhalation of methanol.

Administration, Inhalation↗