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Biomedical subjects

D R Rovner

Publications and source records attributed to D R Rovner.

At least 55 records · Page 3Linked to original sources
PubMed1982

A preclinical course in decision making.

An existing multidisciplinary sequence in the preclinical curriculum of the College of Human Medicine at Michigan State University has been revised to include emphasis on psychological principles of clinical reasoning, decision analysis, ethical issues, and health economics. The course is a four-term sequence taught in the first and second years. In each term, the course consists of a one-hour lecture and two hours of group discussion weekly. The focus of the discussions is a series of carefully constructed paper-and-pencil cases that are graded in difficulty and coordinated with concurrent or previous biological science courses. Examinations have been developed based on written cases and using multiple choice, true-false, and short essay questions. The course is aimed at bringing about fundamental change in the new physicians' conceptions of value and benefit, the way uncertainty is managed, and the traditional belief that data and information are identical.

Curriculum↗
PubMed1981

Plasma cryoactivated renin and active renin in diabetes mellitus.

PRA and the inactive renin which is activated by cold (IR-C) were studied in a group of normal subjects and in patients with diabetes mellitus with and without the presence of nephropathy. The amount of renin activity, as measured after incubation of plasma at -5 C for 4 days, was called cold renin activity (CR. PRA was measured by a standard method. The difference between CR and PRA was used as a measure of IR-C. CR and PRA measurements were made on a normal salt diet, on a low salt diet, and after the administration of furosemide. In all three groups, CR and PRA were higher after salt depletion and following the administration of furosemide. A moderate but significant increase in IR-C was observed with these maneuvers in both groups of diabetes but not in normals. PRA and IR-C varied under different experimental conditions independent of each other. Although both PRA and IR-C were correlated with CR, no correlation was observed between PRA and IR-C. These findings suggest, although they do not prove, that the inactive renin is not a precursor of active renin. CR and IR-C were not significantly different between groups. PRA in patients with uncomplicated diabetes mellitus was normal or slightly high, whereas it was suppressed in patients with diabetes mellitus and nephropathy. The mechanism of suppressed PRA in patients with diabetes mellitus is not clear and may be related to the onset of renal disease itself.

Adult↗
PubMed1980

Pregnancy in hypothalamic hypopituitarism.

Pregnancy in hypopituitarism is distinctly rare. The authors have recently seen a 26-year-old white woman who had amenorrhea. Endocrine evaluation demonstrated hypogonadotropic hypogonadism, decreased adrenocorticotropic hormone reserve, and low normal thyroid function. The patient, treated with estrogen replacement for a few cycles and with physiologic doses of hydrocortisone, spontaneously conceived and delivered a premature infant. The circumstantial evidence favored the occurrence of a spontaneous ovulation. The possibility that prior administration of cyclic estrogens and/or physiologic doses of cortisone facilitated gonadotropin release and subsequent ovulation remains unclear but cannot be completely excluded. The onset of premature labor may have been related to hypofunction of the anterior pituitary.

Adrenal Cortex Hormones↗
PubMed1979

Effect of tolbutamide on plasma renin activity.

The effect of tolbutamide on renin secretion in rats was studied in vivo, and in vitro. Administration of tolbutamide in doses of 12.5 and 25 mg/kg body wt ip to two groups of rats produced no significant change in plasma renin activity compared to the control group. In the in vitro experiments renal cortical slices were incubated with increasing concentrations of tolbutamide (0--4 mg/ml). No significant increase in the net renin production was observed, whereas the concentration of cyclic AMP increased significantly in the incubation medium. These findings suggest that in the intact rats tolbutamide does not increase plasma renin activity. In the renal cortical experiments although tolbutamide increased cyclic AMP production, the increase may not have been sufficient to stimulate the net renin production. These results are of biological significance because of the possible effects of tolbutamide and increased plasma renin activity on the cardiovascular system.

Animals↗
PubMed1979

17 alpha-Hydroxylase deficiency. A combination of hydroxylation defect and reversible blockade in aldosterone biosynthesis.

We have studied the hormonal secretion and excretion patterns in a patient with the XX type of 17 alpha-hydroxylase deficiency. In the untreated state, the patient's urine contained only those steroids which do not require 17-hydroxylation in their biosynthesis. Aldosterone was not produced in the patient and the metabolic product of its immediate precursor, 18-hydroxy-11-dehydro-tetrahydrocorticosterone, was excreted in markedly elevated amounts. This apparent complete block in 18 oxidation was reversible upon long-term ACTH suppression within 27 days. Direct in vitro incubation of the patient's adrenal gland removed at operation demonstrated, 1) the complete lack of 17 alpha-hydroxylase activity, 2) the functional block in the ability to oxidize the hydroxyl group at the 18 methyl side chain. The addition of physiological concentrations of angiotensin to the incubation medium further showed, 3) angiotensin mildly stimulated the entire aldosterone biosynthetic pathway, 4) angiotensin directly stimulated the conversion of 18-hydroxycorticosterone to aldosterone. We propose that in this patient, 17-hydroxylase deficiency produced a decreased plasma concentration of cortisol, followed by stimulation of deoxycorticosterone production by ACTH. The resultant increase in extracellular fluid volume suppressed plasma renin activity. This resulted in a low plasma concentration of angiotensin II which directly suppressed oxidation of 18-hydroxycorticosterone to aldosterone. This defect has been called corticosterone methyl oxidase defect type 2.

18-Hydroxycorticosterone↗
PubMed1977

Spironolactone and hydrochlorothiazide in normal-renin and low-renin essential hypertension.

The relative blood pressure response and side effects of spironolactone (S), 400 mg/day, and hydrochlorothiazide (H), 100 mg/day, were evaluated in a double-masked crossed comparison. Subjects were 24 essential hypertensives, 13 normal and 11 with low renin activity. Upright renin levels were determined in the AM after 3 days of moderately low sodium diet (less than 100 mEq/day) and at the end of each drug treatment period. The values were not revealed to one investigator until completion of the study. After 4-week placebo control periods, either S or H was given in divided doses for 6 weeks. Blood pressure measurements and side effects were evaluated at biweekly intervals. The fall in blood pressure from control was the same for each drug and was independent of renin activity. Side effects occurred more often in patients treated with S, and H was judged superior by risk/benefit analysis. We conclude that S is no more beneficial than H in hypertensive patients with either low or normal renin activity but induces a higher incidence of adverse effects in the dose used in this study. We found no evidence for a greater effectiveness of S in low-renin essential hypertension.

Adult↗