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Biomedical subjects

J M Reiner

Publications and source records attributed to J M Reiner.

At least 37 records · Page 2Linked to original sources
PubMed1980

Evans blue dye. Accumulation in swine aortic intimal cell collections and atherosclerotic lesions.

A two-part study concerned the accumulation of intravenously injected Evans blue dye in the abdominal aorta of swine. In normolipidemic swine weighing up to 90 kg each, Evans blue accumulated predominantly in areas of the aorta that were the site of intimal smooth muscle cell collections. The second part of the study dealt with Evans blue accumulation in swine with advanced atherosclerosis. The extent of blue staining in these animals was not significantly different than in normolipidemic, nonatherosclerotic swine of the same size. The dye showed a predilection for raised atherosclerotic lesions, but only one quarter of the surface of these lesions was stained. Histologic studies of the uppermost portion of blue and nonblue lesion areas showed that the dye preferentially accumulated in regions with lower concentrations of foam cells. Injected isotopic cholesterol tended to accumulate in the blue rather than the nonblue areas.

Animals↗
PubMed1979

Distribution of intimal smooth muscle cell masses and their relationship to early atherosclerosis in the abdominal aortas of young swine.

In the abdominal aortas of young mash-fed swine, intimal cell masses (pads, cushions) are located predominantly away from blood vessel orifices. They are found scattered throughout the aorta but nevertheless have a definite pattern of distribution. In the distal one half of the abdominal aorta, they are more frequent in the ventral quandrant than in the dorsal or either lateral quadrant. In the proximal half, intimal cell masses are more frequent in the dorsal quadrant. When experimental atherosclerosis is induced in the abdominal aortas of young swine by either a hypercholesterolemic diet or by aortic ballooning followed by a hypercholesterolemic diet, the distribution of early lesions is similar. The lesions are found predominantly in quadrants where intimal cell masses were found to be most frequent in the control group of swine. The results suggest that most of the lesions, though not necessarily all, arose from pre-existing intimal cell masses beneath the aortic surface.

Animals↗
PubMed1978

Senescence: a stochastic molecular control theory.

A theoretical model of transcriptional control, in a preliminary form, is presented. The model has a critical boundary between a region of values in which the system is stable and essentially self-perpetuating and a region in which the essential macromolecules tend to disappear and not to be regenerated. The possibility of the transition results from cell division. Variation in the values of kinetic parameters or fluctuation in the partition of the macromolecules between the daughter cells of a division subject some cells in the population to the instability. Cells on the wrong side of the critical boundary may accumulate in G2, and will eventually die, at rates and frequencies depending on the specific peculiarities of various cell types (e.g., tissues). Such phenomena, in association with the characteristic division patterns predicted by the theory, have been observed in vitro and in vivo. "Programmed death" in morphogenesis may be an instance. Problems in the future development of the theory are outlined. The significance of clonal selection for atherogenesis and perhaps oncogenesis is noted. The theory is briefly contrasted with "damage" and "error" theories; and the eventual possibility of constructive intervention in ageing at the molecular level is suggested.

Aging↗
PubMed1978

Tissue mosaics and clonal mechanisms of atherogenesis.

It is known that atherosclerotic lesions arising in aortae of females heterozygous for the A and B variants of glucose-6-phosphate dehydrogenase are frequently though not invariably of one enzyme type. The occurrence of heterotypic lesions rules out single-cell origin. However, it is possible to analyze the results of such studies in terms of multicellular atherogenic foci. The variance in enzyme proportions in the normal tissue mosaic permits an assessment of clump or patch size. Then an application of geometrical probability permits the derivation of a relation between the proportion of monotypic lesions and the size and cell number of the original atherogenic focus. Comparison with suitable experimental data gives reasonable estimates of these cell numbers. The influence of selection in the cell population on such estimates is considered.

Arteriosclerosis↗
PubMed1978

Control of placental 3 beta-hydroxy-delta 5-steroid dehydrogenase: an apparent endogenous regulator of porgesterone synthesis.

Dilution of tissue fractions from human placenta resulted in an increase in the specific activites of 3 beta-hydroxy-delta 5-steroid dehydrongease and of 20 alpha-hydroxysteroid dehydrogenase. The apparent Ks and V max of 3 beta-hydroxy-delta 5-steroid dehydrogenase were altered. It is postulated that this dilution effect is caused by the presence in the placenta of an endogenous inhibitor of steroid synthesis which may be important in the regulation of steroid output by this organ. A mathematical model of such an inhibitor corresponds well to the experimental results.

20-Hydroxysteroid Dehydrogenases↗