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Biomedical subjects

C L COMAR

Publications and source records attributed to C L COMAR.

At least 55 records · Page 3Linked to original sources
PubMed1959

Metabolic dissociation of short-lived barium-137m from its cesium-137 parent.

At 4 to 7 days after Cs(137) administration, Ba(137m) was found to exceed Cs(137)-Ba(137m) equilibrium proportions in bone and plasma by factors of 3 and 14, respectively, in the living animal. This demonstrated the in vivo escape of Ba(137m) from sites of Cs(137) accumulation. Liver tissue was slightly deficient in Ba(137m), whereas tissues such as bone marrow and spleen showed little or no deviation from equilibrium.

Animals↗
PubMed1957

Strontium-calcium movement from soil to man.

The calcium reservoirs of the biosphere are becoming labeled to varying degrees with strontium-90 from nuclear weapons. These reservoirs include the human and animal skeleton, the milk, the vegetation, the upper layers of soil, and the waters. The degree of labeling is governed by the dilution that occurs, or the differential behavior of calcium and strontium in various steps of the food chain. This differential behavior normally provides a factor of protection against strontium-90 in the soil and vegetation that may be as high as 25 for the newborn and is most likely not less than 6 for adults, depending on food habits. The physiological steps that are important in the movement of the two elements in the biosphere are described to provide a basis for an approach toward increase of the discrimination against strontium in favor of calcium. Some aspects of agricultural practices are discussed from this standpoint. The matter of hazard from levels now existing and the present need to undertake remedial measures are not discussed, in major part because of lack of experimental data on which to base such considerations.

Adult↗
PubMed1957

The effects of fluoride feeding on the organic matrix of bones and teeth of pigs as observed by autoradiography after in vitro uptake of Ca45 and S35.

Demineralized sections of fluorinated bones and teeth have been studied by autoradiography following in vitro uptake of Ca(45) or S(35)O(4). The portions of tissue which do not become mineralized (cartilage, prebone, predentine, and precementum) show an increased Ca(45) uptake apparently related to an increase in chondroitin sulfate content in fluorosis. The tissues from the fluoride-fed animals show an increase of in vitro uptake of sulfur in the tissues which become mineralized (bone, dentine, cementum).

Animals↗
PubMed1957

Autoradiographic studies of the utilization of S35-sulfate by the chick embryo.

From studies of autoradiograms of various developmental stages of the chick embryo containing S(35) given us sulfate it was determined that as early as Stages 3+ and 4 there is a selective utilization or accumulation of sulfate by the various parts. The earliest accumulation site is the axial portion of the primitive streak and the floor of the groove. Later S(35) was found in the head process, Hensen's node, notochord, amniocardiac vesicle, wall of the omphalomesenteric vein, endocardium, subendocardial jelly, mesenchyme destined to become cartilage, basement membrane area of the gut, and a mucopolysaccharide layer formed on the free surface of the stomach. The early notochordal localizations of S(35) coincide with the region in which a thin ring of chondroitin sulfate is subsequently laid down. However, it is apparent that there is an intracellular accumulation of inorganic sulfate by the chondroitin-forming cells prior to the time they produce sufficient chondroitin sulfate to be demonstrable histochemically. It was interesting to note that the endocardium appears to concentrate sulfate that later apparently finds its way into the subendocardial jelly. The fact that those mesenchymal cells which later form chondroblasts begin to utilize sulfate selectively before histological differentiation is apparent was determined. In addition, the presence of sulfate-containing substances in the forming basement membrane of the gut would seem to indicate that sulfate is important in the histological differentiation of this membrane.

Animals↗