Biomedical subjects
Publications and source records attributed to C Garcia.
A single dose of calcitonin (150 mIU/100 g body weight, sc) produced a significant decrease in liver antipyrine hydroxylase and aminopyrine demethylase activities. By contrast, pentobarbital sleeping time was not altered by calcitonin treatment. The present results indicate that acute calcitonin administration depresses the metabolism of substrates of the mixed function oxidase system of rat liver.
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Denervation-induced supersensitivity of the striatal dopamine receptors can be quantified by the turning behaviour induced by apomorphine. With this experimental model we found that high-dose L-dopa/carbidopa administration reduced this supersensitivity. This effect was seen on the 1st day and did not alter over 5 or 10 days of treatment, but disappeared when medication was discontinued. The degree of reduction was the same, independent of the dose and period of administration. This effect could provide a useful model for studying the phenomenon of the irreversibility of the supersensitivity of the striatal dopamine receptors.
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A study of the structural characteristics of stage 5 chick embryo blastoderms, cultured in vitro, was carried out after previous elimination of endoderm to analyse the differentiation capacity of mesoderm. Our results show that only the precardiac mesoderm is determined at this early stage and that it is able to differentiate cardiac tissue in the absence of the endoderm. The ultrastructural characteristics of this tissue are described. However, the degree of differentiation of cardiomyoblasts does not reach the expected level of organization and myofibrillar complexity.
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The barium enema (BE) may be useful in the diagnosis of atypical appendicitis in children. We analyzed our experience with 18 children in whom appendicitis was suspected and BE was performed. All of the children underwent surgical exploration. Nonfilling of the appendix with cecal indentation, extravasation of barium from the appendix, or both, were considered positive signs of an inflamed appendix on BE. Using these criteria, 12 of 14 cases of proved appendicitis were true positive and two were equivocal. Four children were proved not to have appendicitis; one of these patients had a true-negative BE, two had equivocal BEs, and there was one false-positive BE (Schönlein-Henoch purpura). Extravasation of barium into the peritoneal cavity was noted in one patient; this was a rare complication.
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Histopathological examination of liver and lung in guinea pigs experimentally intoxicated by 3HMI, a degradation product of an allelochemic of Brassica spp, showed the harmful effects of this compound on these organs. The 3HMI produces a hepatic steatosis and interstitial pneumonia with septal hyperemia. These results suggest that the 3HMI could develop a synergic toxic action together with skatole (3MI) as inducing agents of different forms of some diseases detected in cattle grazing Brassica pasture.
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Ninety-three homosexual men with persistent lymphadenopathy were followed at the Memorial Sloan-Kettering Cancer Center for a mean period of 20.8 months. Histories and serologic evidence of a number of previous infections were common, but the lymphadenopathy was not due to recognizable infections or neoplastic disease. Leukopenia, lymphopenia, granulocytopenia, monocytopenia, decreased ratios of T-helper to T-suppressor cells, decreased natural killer cell activity and increased serum immunoglobulin concentrations were common. Lymph node biopsies showed reactive hyperplasia without any unique histopathologic features. Antibody to the human T-lymphotropic virus-III (HTLV-III or LAV), a newly described retrovirus believed to be the etiologic agent of the acquired immune deficiency syndrome (AIDS), was detected in 91.4%. Over a 3-year period, 11 cases of AIDS were recognized in these patients: Kaposi's sarcoma developed in 7 and opportunistic infections in 4. The lymphadenopathy resolved in six patients and the others remained unchanged. Although most of these patients are asymptomatic and remain well, the risk of AIDS in this group of men was higher than in other groups of homosexual men in New York.
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To study the distribution of alpha 1-adrenergic receptors in rat heart, kidney, and skeletal muscle, we used light-microscopic autoradiography of [3H]prazosin. Scintillation spectrometry of frozen sections demonstrated rapid binding, saturability, stereospecificity, and agonist and antagonist binding characteristic of an alpha-receptor. For autoradiography, sections were incubated, processed, and grain density quantified using a computer-based image analyzer. Specific alpha 1-receptor binding was found over cardiac myocytes in the left and right ventricles but not over skeletal muscle. Scatchard analyses of specific grain densities over cardiac myocytes gave a dissociation constant (Kd) of 0.55 +/- 0.18 nM (SD, n = 4 rats) and a maximum number of binding sites (Bmax) of 448 +/- 90 grains/10(-2) mm2. Renal arterioles had a higher specific grain density than myocardial arterioles at all concentrations of [3H]prazosin (P less than 0.001). Scatchard analyses showed that renal arterioles had a Kd of 0.27 nM and a Bmax of 1,259 grains/10(-2) mm2, whereas myocardial arterioles had a Kd of 1.64 nM and a Bmax of 183 grains/10(-2) mm2. Arterioles in the flexor carpi radialis muscle were not labeled. Renal cortex tubules had the highest grain density of any structure studied, i.e., higher than grain density over glomeruli or tubules in the renal medulla. These observations indicate that significant differences exist in the distribution and affinity of alpha 1-adrenergic receptors in various vascular beds and parenchymal tissues.