PubMed Health⌕ Search

Biomedical subjects

M Steer

Publications and source records attributed to M Steer.

28 records · Page 2Linked to original sources
PubMed1984

Inhibition of platelet function by cis-unsaturated fatty acids.

The uptake of free fatty acids has previously been shown to affect the capping of lymphocytes, and there is evidence that different types of fatty acids may partition into separate lipid domains in cell surface membranes. In studies of gel-filtered human platelets, we found that cis-unsaturated fatty acids (1-35 microM) inhibited platelet shape change, aggregation, and secretion of 5-hydroxytryptamine induced by thrombin, adenosine diphosphate (ADP), collagen, U46619 (a thromboxane A2 analog), or plant lectins, but not that induced by A23187, a calcium ionophore. Trans-unsaturated and saturated fatty acids had little or no inhibitory effect. The inhibitory effects of cis-unsaturated fatty acids were not affected by inhibition of adenylate cyclase or cyclooxygenase. 14C-labeled fatty acids were taken up into platelet lipids. The maximum platelet-inhibitory effect of cis-unsaturated fatty acids was seen when over 90% of the platelet label was still in the form of free fatty acids. Platelet inhibition could be reversed by washing the platelets by gel filtration. Binding of platelet agonists to the platelet was not inhibited by the fatty acids. Cis-unsaturated fatty acids, but not trans-unsaturated or saturated fatty acids, decreased fluorescence polarization of platelets or isolated platelet membranes monitored with 1,6-diphenyl- 1,3,5-hexatriene. The potency of the fatty acids as inhibitors of platelet aggregation was inversely correlated with their melting points. These data suggest that inhibition of receptor-mediated platelet responses by cis-unsaturated fatty acids results from perturbation of the platelet membrane in specific lipid domains.

Blood Platelets↗
PubMed1983

In search of the biopsychosocial perspective: an experiment with beginning medical students.

The authors assessed the clinical thinking of medical students before, during, and after their first extensive in-hospital learning experience and exposure to physician role models. They found that more than 90% of the students' requests for additional data in response to videotaped simulated patient interviews were for biologic information; approximately 66% of all respondents in six separate trials failed to request a single psychological or social item concerning the patient. The authors discuss the pervasiveness of the biomedical rather than the biopsychosocial mentality and its implications for medical education as well as clinical teaching, decision making, and practice.

Adult↗
PubMed1980

A defect in platelet aggregation in Bartter's syndrome.

A defect in both the first and second phase of platelet aggregation was found in four subjects with Bartter's syndrome, although template bleeding times were normal. The platelet abnormality was exacerbated by restriction of dietary sodium and lessened by the administration of inhibitors of prostaglandin synthesis. The aggregation defect was not found in other hypokalemic patients or in sodium-restricted normal control subjects. Platelet rich plasma from the subjects with Bartter's syndrome had an abnormally high content of cyclic adenosine 5'-monophosphate (AMP), which may have been responsible for the disordered platelet function. Plasma of these subjects induced both the high content of cyclic AMP and the aggregation defect in normal platelets, whereas suspension of the subjects' platelets in normal plasma improved their aggregation. These findings describe a unique defect of platelet aggregation in Bartter's syndrome, which may be associated with the altered prostaglandin metabolism found in this condition.

Adolescent↗
PubMed1980

Recognition of adrenal insufficiency in the postoperative patient.

The signs and symptoms of adrenal insufficiency in the postoperative patient are generally nonspecific, and the diagnosis is usually made at postmortem examination. Two patients in whom adrenal insufficiency developed in the postoperative period are reported on (one had metastatic carcinoma to the adrenal glands and in the other bilateral adrenal hemorrhage developed during anticoagulant treatment). Both patients survived multiple, successive stressful episodes before the diagnosis of adrenal insufficiency was established by the alpha1-24 corticotropin stimulation test.

Adenocarcinoma↗
PubMed1980

Determinants of adverse reaction following postoperative T-tube cholangiogram.

The incidence, nature, and mechanisms of adverse reaction following postoperative T-tube cholangiogram have received little attention in the medical literature. This paper presents the experience at one hospital over a 30-month period (1975--1977) covering 139 patients who had 170 cholangiograms. Factors examined included intraoperative and postoperative cultures of bile, the use of antibiotics prior to the performance of the cholangiogram, the technique of cholangiography, the interval between operation and cholangiogram. Eleven (6.5%) cholangiograms were followed by an adverse reaction. Two of these reactions were severe, manifested by signs of septic shock. The administration of antibiotics was not associated with a reduction in adverse reactions. The cholangiographic technique of gravity infusion of dye, which effectively limits the amount of pressure generated during the study, was associated with a significant reduction in adverse reactions. No severe reactions occurred following any study performed by the gravity technique. There was no significant correlation between the age of the patient or the number of days postoperative with adverse reaction. A review of the literature suggests that the mechanism for these severe reactions is cholangiovenous reflux. The avoidance of high intraductal pressures (above 25 cm of water) during the performance of postoperative T-tube cholangiogram should significantly reduce the incidence of adverse reactions.

Adolescent↗
PubMed1975

Diagnostic and therapeutic considerations for fecal impaction.

During an 18-month period, 18 patients were admitted to the Beth Israel Hospital because of fecal impaction or its complications. The records of the 18 patients were reviewed to determine the presenting signs and symptoms, radiologic findings, course and etiology of fecal impaction. Prior use of drugs that slow gastrointestinal motility was found in seven cases, and seven of the 18 patients had severe neuropsychiatric illness. The presenting signs and symptoms in almost all instances were consistent with a diagnosis of intestinal obstruction. The difficulty in differentiating intestinal obstruction caused by fecal impaction from obstruction resulting from other lesions is discussed. The diagnosis of fecal impaction should be entertained only after other causes of intestinal obstruction have been excluded.

Adolescent↗