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Biomedical subjects

J R Gavin

Publications and source records attributed to J R Gavin.

70 records · Page 4Linked to original sources
PubMed1975

Radioreceptor assay of insulin: Comparison of plasma and pancreatic insulins and proinsulins.

Porcine proinsulin, related intermediates and plasma immunoreactive insulin components have been studied by radioreceptor assay. Using the purified rat liver membrane or cultured human lymphocyte radioreceptor assay, porcine proinsulin is %5, split proinsulin 6% (54-55 split in connecting peptide) desdipeptide proinsulin 20% (deletion of amino acids 62 and 63 of connecting peptide) and desnonapeptide proinsulin 27% (deletion of amino acids 55-63 of connecting peptide) as active as porcine insulin in both assay systems; these values closely parallel the in vitro bioactivity of these preparations. In the lymphocyte radioreceptor assay the human plasma immunoreactive insulin-like component has the same potency as porcine insulin per immunoreactive unit, whereas the plasma immunoreactive proinsulin-like component is only 15% as active. Since both plasma immunoreactive components are somewhat less reactive than would be expected from puriified human insulin and proinsulin, the data suggest that both plasma components contain immunoreactive molecules that do not react in the radioreceptor assay.

Animals↗
PubMed1974

Insulin-dependent regulation of insulin receptor concentrations: a direct demonstration in cell culture.

Chronic (5-16 hr) exposure of cultured human lymphocytes to 10(-8) M insulin at 37 degrees in vitro produced a decrease in insulin receptor concentrations unaccounted for by simple occupancy of sites; acute exposure (0-2 hr) was without effect. These results reproduced observations in vivo where chronic hyperinsulinemia (e.g., 10(-8) M insulin in the circulation of obese insulinresistant hyperglycemic mice) is associated with a substantial reduction in the concentration of insulin receptors per cell, while acute hyperinsulinemia in vivo has no effect on receptor concentration. These data suggest a reciprocal relationship between insulin in the extracellular fluid and the concentration of insulin receptors per cell, which is mediated at the target cell itself by intracellular insulin-sensitive regulatory processes and directly affects target-cell sensitivity to hormone.

Binding Sites↗
PubMed1972

Water-soluble insulin receptors from human lymphocytes.

Specific insulin receptors from human lymphocytes in culture have been prepared in aqueous solution without use of detergents or related compounds. Receptors prepared in this fashion exhibit characteristics identical to those reported in intact cells.

Adrenocorticotropic Hormone↗
PubMed1972

Insulin receptors in human circulating cells and fibroblasts.

Human lymphocytes obtained from fasted adult subjects and cultured human tumor lymphocytes were investigated for specific insulin receptors. By use of monoiodoinsulin, specific insulin binding sites were demonstrated in peripheral human lymphocytes, cultured human lymphocytes, and in other types of human circulating cells. Insulins and insulin derivatives that varied in their potency to stimulate glucose oxidation in the fat cell and to inhibit binding of [(125)I]insulin to purified plasma membranes, varied in an analogous fashion in their ability to inhibit the binding of labeled insulin to human lymphocytes. Hormones that had no effect on the binding of insulin to fat cells or liver membranes also had no effect on the binding of insulin to lymphocytes. Binding was time and temperature dependent; dissociation of [(125)I]insulin was rapid upon addition of 10 muM insulin. These findings afford a direct approach to the study of endocrine disorders in man.

Adult↗
PubMedDate not supplied

Coronary heart disease in African Americans.

African Americans have the highest overall mortality rate from coronary heart disease (CHD) of any ethnic group in the United States, particularly out-of-hospital deaths, and especially at younger ages. Although all of the reasons for the excess CHD mortality among African Americans have not been elucidated, it is clear that there is a high prevalence of certain coronary risk factors, delay in the recognition and treatment of high-risk individuals, and limited access to cardiovascular care. The clinical spectrum of acute and chronic CHD in African Americans is similar to that in whites. However, African Americans have a higher risk of sudden cardiac death and present more often with unstable angina and non-Q-wave myocardial infarction than whites. African Americans have less obstructive coronary artery disease on angiography, but may have a similar or greater total burden of coronary atherosclerosis. Ethnic differences in the clinical manifestations of CHD may be explained largely by the inherent heterogeneity of the coronary syndromes, and the disproportionately high prevalence and severity of hypertension and type 2 diabetes in African Americans. Identification of high-risk individuals for vigorous risk factor modification-especially control of hypertension, regression of left ventricular hypertrophy, control of diabetes, treatment of dyslipidemia, and smoking cessation--is key for successful risk reduction.

Age Factors↗