Search PubMed⌕ Search

Biomedical subjects

M Mersel

Publications and source records attributed to M Mersel.

44 records · Page 3Linked to original sources
PubMed1984

[Differential action of 7 beta-hydroxycholesterol on myocardial cells and fibroblasts. Obtaining primary cultures of pure myocardial cells].

Newborn rat myocardial cells, grown in primary cultures, beat synchronously. Addition of 7 beta-hydroxycholesterol, at a 2.5 microM concentration, impairs this synchrony and may even stop any contraction. The associated fibroblasts no longer adhere to the support, and can be washed away by fresh culture medium. This restores the synchronous beatings of the myocardial cells, the viability of which is then even improved while they grow in the absence of fibroblasts.

Animals↗
PubMed1983

A study on the topological distribution of phospholipids in microsomal membranes of chick brain using phospholipase C and trinitrobenzenesulfonic acid.

The transbilayer distribution of phospholipids in chicken brain microsomal membranes has been investigated using trinitrobenzenesulfonic acid and phospholipase C from Clostridium welchii. The exposure of intact microsomes to trinitrobenzenesulfonic acid showed that the labelling of aminophospholipids followed biphasic kinetics, indicating that these membranes contain a fast- and a slow-reacting pool of aminophospholipids. Use of microsomes radioiodinated on their surface led to the conclusion that the fast-reacting pool may be located on the outer leaflet of the microsomal vesicles. It contains about 35% of the phosphatidylethanolamine, 29% of the ethanolamine plasmalogens and 18% of the phosphatidylserine. The treatment of intact microsomes with the phospholipase C Cl. welchii produced the hydrolysis of 50% of the phospholipids without any loss of their permeability properties, indicating that they are not permeable to the hydrolase. Phospholipids extracted from the microsomes were hydrolyzed rapidly by the phospholipase C with the exception of phosphatidylserine and phosphatidylinositol. In intact microsomes about 90% of phosphatidylcholine, 32% of ethanolamine phospholipids and 60% of sphingomyelin were accessible to the phospholipase. These results suggest that the phospholipids have an asymmetric distribution in chicken brain microsomes, the external leaflet containing about 75% of the choline phospholipids and 25% of the aminophospholipids, whereas an opposite distribution is observed in the inner leaflet.

Animals↗
PubMed1983

Long-term effects of brain trypsinization before cell seeding on cell morphology and surface composition.

The relation between the pattern of proteins localized in the surface of astroglial cells and cell differentiation was investigated in primary cultures derived from neonatal rat brains, dissociated either mechanically (MDC) or by 3 (TDC3) and 30 minutes (TDC30) trypsinization. Morphological and ultrastructural studies revealed a bed layer composed of flat, polygonal young and differentiated astrocytes in all types of cultures and a surface layer composed of small, ovoide undifferentiated cells which were more numerous in TDC30 than in TDC3 and MDC. The enrichment in undifferentiated cells, induced by prolonged brain trypsinization prior cell seeding, was observed during two weeks in culture; latter, by day 20, the cell population in all cultures was that of differentiated astrocytes. The presence of structural and enzymatic cell markers indicated that the cell population in MDC and TDC3 as well as in TDC3, including the small cells, was of astroglial origin. Concomitant with the morphological changes, cells in TDC30 were less accessible to surface labeling than those composing MDC. Subsequent electrophoresis of the labeled surface proteins demonstrated that a 140-130 K complex was the most "sensible" to brain trypsinization and that their accessibility to the surface probing was maximal during the differentiation of astrocytes in MDC or of small cells in TDC30. By day 20, these components were not significantly labeled in both, MDC, and TDC30, cultures. The use of two types of astrocytes primary culture which were different in the ratio of differentiated to undifferentiated cells and their surface labeling at different growth stages showed a variation in the composition of surface proteins during the cell maturation. The increased accessibility of some surface proteins to external probing when the cells developed to differentiated astrocytes might suggest their involvement in cell differentiation.

Animals↗
PubMed1979

Intracellular lipase activities in heart and skeletal muscle homogenates. The absence of trierucin cleavage by the heart: a possible biochemical basis for erucic acid lipidosis.

Rat heart and skeletal muscle homogenates were compared for their intracellular lipolytic activity towards a series of saturated and unsaturated triglycerides from trilaurin (C12:0) to trierucin (C22:1). It is shown that for all triglycerides esterified with fatty acids from C12 to C18, lipolytic activity in heart homogenates was higher than in skeletal muscle homogenates. For these triglycerides there was no relationship between the fatty acid chain length and the lipolytic activity. In both homogenates cleavage of unsaturated triglycerides was higher than cleavage of the homologous saturated triglyceride. Lipolysis of tri-delta-11-eicosenoin (C20:1) was similar in both homogenates but much lower than lypolysis of other triglycerides. Although cleavage of trierucin (C22:1) was very low in skeletal muscle homogenates, it was undetectable in heart homogenates, even when enzyme concentration was increased. A mixture of triglycerides did not show preferential hydrolysis of any simple triglyceride. Trierucin was the only triglyceride that did not complete for lipolytic activity and only with heart homogenates, which shows that that lipase(s) do not cleave trierucin. The absence of lipolytic activity towards trierucin in heart homogenates could explain the selective accumulation of erucic acid-rich triglycerides in hearts of animals fed a diet with a high erucic acid content.

Animals↗