Biomedical subjects

T D Warner

Publications and source records attributed to T D Warner.

133 records · Page 8Linked to original sources

PubMed1989

Comparison of the survival of endothelium-derived relaxing factor and nitric oxide within the isolated perfused mesenteric arterial bed of the rat.

1. The survival of the endothelium-derived relaxing factor (EDRF) released by acetylcholine (ACh) in the rat isolated perfused mesenteric vascular bed was compared to that of exogenously applied nitric oxide (NO) by direct bioassay of the effluent from the mesenteric bed on rabbit aortic strips (RbAs). 2. NO (0.1-10 nmol) produced dose-related vasodilatations in the mesenteric vascular bed and also survived in the effluent in concentrations sufficient to provoke relaxations of the RbAs. ACh (1.7 pmol-300 nmol) caused dose-related vasodilatations in the mesenteric bed but no EDRF was detected in the effluent. This was true even when ACh provoked much larger vasodilatations in the mesenteric bed than those to doses of NO that survived passage through the bed. 3. Removal of the endothelial cells in the mesenteric vascular bed abolished vasodilatations in response to ACh but did not significantly affect those to NO. Survival of NO through the mesenteric bed was not increased. 4. Superoxide dismutase (SOD, 10 u ml-1) did not significantly affect the vasodilator effects of either ACh or NO. It did increase the survival of NO through the mesenteric vascular bed but native EDRF was still not detected in the effluent. 5. The absence of bioassayable EDRF in the effluent following ACh-induced vasodilatations might be explained by the volume into which EDRF is released abluminally being much smaller than that into which it is released luminally.

Animals↗

PubMed1988

Pressor effects of circulating endothelin are limited by its removal in the pulmonary circulation and by the release of prostacyclin and endothelium-derived relaxing factor.

Endothelin releases prostacyclin and thromboxane A2 from guinea pig or rat isolated lungs and endothelium-derived relaxing factor in the perfused mesentery of the rat. Endothelin is also substantially removed by the pulmonary circulation of the rat in vitro and in vivo and by guinea pig lungs in vitro. In the rat, the effects of endothelin on the blood pressure vary from pressor (in pithed rats) to purely depressor in anesthetized rats where the resting blood pressure is high. It therefore has the characteristics of a local pressor hormone, rather than a circulating one.

Animals↗

PubMed1988

Receptor-mediated release of endothelium-derived relaxing factor and prostacyclin from bovine aortic endothelial cells is coupled.

Bovine aortic endothelial cells were grown on microcarrier beads and were perfused with Krebs-Ringer solution. Endothelium-derived relaxing factor (EDRF) was bioassayed on a cascade of four strips of rabbit aorta, and prostacyclin was analyzed by RIA of 6-oxo-prostaglandin F1 alpha. The endothelial cells released EDRF and prostacyclin when stimulated with bradykinin and its analogues, or with ADP, ATP, arachidonic acid, and phospholipase C (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3). The detection of EDRF was potentiated by superoxide dismutase, and the relaxation of rabbit aortic strips induced by EDRF was antagonized by methylene blue. The release of EDRF and prostacyclin was inhibited by phorbol myristate acetate, R59022 (a diacylglycerol kinase inhibitor), and gentamycin. We suggest that the release of EDRF and prostacyclin is coupled and the initial common step is activation of a phospholipase C.

Animals↗

PubMedDate not supplied

Attitudes of consultation-liaison psychiatrists toward physician-assisted death practices.

The objective of this study was to investigate the views of consultation-liaison (C-L) psychiatrists on assisted-death practices. A 33-question anonymous survey was distributed at the Academy of Psychosomatic Medicine Annual Meeting in November 1995. The instrument explored perceptions of acceptability of assisted death in six hypothetical patient situations as performed by four possible agents. The response rate was 48% (184 conference attendees participated, i.e., completed and returned the surveys). With little variability, the respondents were unwilling to perform assisted death personally and also did not support assisted death as performed by nonphysicians. The respondents were somewhat more accepting of referral or other physicians' involvement in such practices. Assisted death was viewed differently than withdrawal of life support. Several variables were analyzed for their influences on the views expressed. The C-L psychiatrists in this study expressed opposition to assisted death practices. Their views varied somewhat depending on the patient vignette and the agent of death assistance. The authors conclude that C-L psychiatrists may wish to develop their present therapeutic and evaluative role in patient care to alleviate suffering, without hastening patient death.

Adult↗

PubMedDate not supplied

Medical students' evolving perspectives on their personal health care: clinical and educational implications of a longitudinal study.

The mental and physical health care issues of medical students are increasingly recognized as both prevalent and complex. Emotional distress, symptoms of mental illness, and maladaptive substance use are widespread and may often be driven by training-related stressors. The data suggest that nearly all medical students identify physical health concerns as well. The care of medical students as patients is complex because of problems associated with the stigma of various illnesses and the dual role of trainee and patient in medical school. A written confidential survey assessed students longitudinally near the end of their first and third years of training regarding their perceived health care needs, health concerns, attitudes toward care, access to services, and care-seeking practices (161 items). A subset of students (n = 33) were reassessed 1 month after the second survey to measure reliability. McNemar's chi-square (chi2) tests, repeated-measures multivariate analysis of variance (MANOVA), and K and Pearson correlations were used to evaluate outcomes. Almost all students reported health care needs during both training phases, and their mental and physical health concerns were stable over time. However, the preference for obtaining health care at a site other than their training institution and concerns about confidentiality increased, although students were marginally more likely to obtain care at their medical school during clinical versus preclinical training. The students' tendency to seek informal care from colleagues remained consistent, as did their high level of concern about professional jeopardy relating to personal health issues. Their tendency to accept the dual patient-student role depended on the particular health care issue; they expressed a strong tendency to protect other students' confidentiality, even in cases of potential significant impairment. Responses were reliable across a 1-month retest interval. We conclude that medical students' perspectives on their mental and physical health care across the transition from preclinical to clinical training reveal the importance of pursuing, not neglecting, a number of clinical and educational initiatives. Through their specialized expertise, psychiatrists may help to ensure sound mental and physical health care for the more than 69,000 medical students in training in this country.

Adult↗

PubMedDate not supplied

Perceptions of academic vulnerability associated with personal illness: a study of 1,027 students at nine medical schools. Collaborative Research Group on Medical Student Health.

About one quarter of the more than 69,000 medical students in this country suffer symptoms of mental illness, including 7% to 18% with substance use disorders. Subjective distress and physical health needs of medical students are also common and have been linked to training stresses. This first large-scale study of medical student health care examined students' physical and mental health concerns and their perceptions of academic vulnerability associated with personal illness. A 7-page, confidential written survey was given to 1,964 students at nine US medical schools in 1996 and 1997. A total of 1,027 students participated (52% response rate). Nearly all (90%) reported needing care for various health concerns, including 47% having at least one mental health or substance-related health issue. A majority of students expressed a preference for health care outside their training institution, largely due to confidentiality concerns, and 90% preferred health insurance allowing off-site care. Students expressed varying levels of concern about academic jeopardy in association with personal illness, with physical health problems such as arthritis causing the least concern and alcohol and drug abuse triggering the most concern. Consistent differences were detected in these views based on respondent's gender, training level, and institution. Most medical students perceive the need for personal health care. Nevertheless, fear of academic reprisal may prevent medical students from seeking necessary care for their health problems during training. This phenomenon may be linked in important but poorly recognized ways to emerging illness and to impairment among medical students and physicians. Women, minority, and clinical students appear more sensitive to the connection between health and academic vulnerability. Constructive implications for medical school curricula, policies, and health care services are discussed.

Adult↗

PubMedDate not supplied

Relationship between different isoforms of nitric oxide synthase and cyclooxygenase in various cell types.

Nitric oxide (NO) and prostacyclin (PGI2), formed by NO synthase (NOS) and cyclooxygenase (COX), respectively, are two potent anti-aggregatory vasodilators released from endothelial cells. Both NOS and COX exist as constitutive and inducible isoforms. We have shown that NOS and COX are co-induced in vitro and in vivo by bacterial endotoxin and that low amounts of NO increase whereas high amounts inhibit the activity and expression of inducible COX in vitro.

6-Ketoprostaglandin F1 alpha↗