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Biomedical subjects

H B Bosmann

Publications and source records attributed to H B Bosmann.

At least 73 records · Page 4Linked to original sources
PubMed1976

Erythrocyte surface membrane alterations.

Electrophoretic mobility measurements were made of red blood cells obtained from patients with Duchenne and myotonic muscular dystrophy, from dystrophic mice and chickens, and from corresponding controls. Alterations in the erythrocyte surface electrokinetic properties were found in dystrophic mice and chickens and in many, but not all, patients with muscular dystrophy. The results are consistent with the concept of muscular dystrophy as a systemic membrane disease not limited to muscle.

Adolescent↗
PubMed1976

Neutral protease activity of Rous sarcoma (RSV) transformed chick embryo fibroblasts.

The proteolytic activities of normal, Schmidt-Ruppin Rous sarcoma virus (SR-RSV) transformed, and infected (RAV) chick embryo fibroblasts (CEF) have been measured by a highly sensitive technique using 3H-acetylated haemoglobin as a substrate. When all 3 types of CEF cells were maintained in serumless media, no differences were detected in the amount of pH 3-4 protease activity released into the media over a 24-h period, and only negligible amounts of pH 7-6 proteolytic activity were found. When normal, transformed, and infected cells were maintained in serumless media and later incubated with 3H-acetylate haemoglobin, a significant proteolysis of the haemoglobin, a 6-fold increase compared to the normal CEF cells, was associated only with plates containing SR-RSV-CEF cells. A fluorescent assay for peptides confirmed that SR-RSV-CEF cells have increased cell-associated proteolytic activity. The net surface charge of the transformed CEF cells was unchanged by maintenance in serumless media but the net surface negativity of the normal and RAV-CEF cells was significantly increased by incubation in media minus serum for 24 h. This suggests that normal CEF cells, maintained in media plus serum, have a substance masking their surface charge which is absent from the surface of transformed cells, possibly because of proteolytic degradation.

Avian Leukosis Virus↗
PubMed1975

Cell-cell interactions: enhancement of glycosyl transferase ectoenzyme systems during Chlamydomonas gametic contact.

Glycosyl transferase ectoenzyme systems that transfer galactose, glucose, N-acetylglucosamine, N-acetylneuraminic acid, mannose, and fucose have been detected on vegetative cells and gametes of Chlamydomonas moewusii. Gametes have higher levels of activity of the transferase ectoenzyme systems than morphologically identical vegetative cells, as determined by transfer of monosaccharide onto endogenous cell surface acceptors. When (plus) and (minus) gametes are mixed, there is a significant increase in the activity of transferase ectoenzyme systems. No enhancement in activity of transferase ectoenzyme systems occurs when (plus) and (minus) vegetative cells are mixed. Flagellar membrane vesicles obtained from (plus) and (minus) gametes show high activity of transferase ectoenzyme systems per mg of protein and also demonstrate enhanced activity upon mixing. Therefore, glycosyl transferases and acceptors seem to be located on the flagellar membrane and appear to have a function particularly related to gametic cells. The mechanism of cellular adhesion or recognition proposed by Roseman (1970, Chem. Phys. Lipids 5, 270-297), involving glycosyl transferases and acceptors, is strongly suggested by our data for the mating reaction in Chlamydomonas.

Binding Sites↗
PubMed1975

Cell surface changes accompanying viral transformation: N-acetylneuraminic acid ectotransferase system activity.

The activity of the sialyl ectotransferase system of normal chick embryo fibroblasts (CEF) and chick embryo fibroblasts transformed with the Schmidt-Ruppin strain of Rous sarcoma virus (SR-RSV) have been compared. Neuraminidase treatment of the intact cells increased the sialyl ectotransferase system activity of control and transformed cells two to three times. The ectotransferase system activity increased as the pH was decreased from 7.8 to 6.0. The temperature optimum for both systems was 40 degrees C. Approximately 60% of the 14C-sialic acid incorporated at pH 6.5 or above could be removed with neuraminidase. The activity of the transformed cell system with or without neuraminidase treatment was more stimulated by addition of Mn2+ ions, particularly above pH 7.0. This difference in ion sensitivity indicates that a different cell surface phenomenon is being studied after transformation.

Acetyltransferases↗
PubMed1975

Studies of enzymes involved in glycoprotein synthesis and degradation in diacetylbenzidine nephrosis.

Diacetylbenzidine was used to induce a nephrotic syndrome in female rats. Enzymes involved in glycoprotein metabolism were evaluated during an early stage of induced renal disease before extensive histologic changes occurred. The results show that lysosomal acid hydrolases are not activated or released to any measurable degree during the early stages of the disease. Minimal differences in the composition of glomerular basement membrane of nephrotic rats were found despite heavy proteinuria. Glomerular specific activities of certain glycoprotein:glycosyl transferases were depressed in nephrotic animals. A new viewpoint to explain the pathology of glomerular proteinuria is presented based on the phenomenon of sublethal autolysis affecting cell surface structure and function, of which activity levels of glycoprotein:glycosyl transferases are an example. Increased activities of glycosyl transferases and Na-D ATPase were noted in the cortex from nephrotic animals. These studies involving cortex indicate that the pathologic process is not confined to the glomerulus and may contribute information concerning Na+ transport in the nephrotic rat.

Acid Phosphatase↗