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Biomedical subjects

M Adam

Publications and source records attributed to M Adam.

At least 181 records · Page 10Linked to original sources
PubMed1983

Are the changes in collagen caused by chronical X-irradiation similar to aging?

It has been shown that in the skin of chronically irradiated rats the proportion of collagen type III as compared to collagen type I is increased; on the other hand, no changes in the overall proportion to collagen were observed in the skin. It appears that the increased proportion of collagen type III in chronically irradiated rats is responsible for the decreased solubility of cutaneous collagen in these animals. Concomitantly, indirect evidence was accumulated for the presence of an additional cross-link in type III collagen, present only when irradiated animals served as the collagen source. This cross-link is located subterminally as long as it is not removed by limited pepsin digestion. It was concluded that the physiological decrease in solubility and the decrease in solubility observed in chronically irradiated animals have a different molecular background.

Aging↗
PubMed1981

High fat diet induced fluorescence and increased resistance of collagen to proteolytic cleavage.

Feeding of animals with high fat diets results in a distinct increase in the stability of the collagen structure as reflected by its higher resistance towards proteolytic cleavage. It appears that covalent cross links are formed when the experimental animals are fed a diet containing a high proportion of unsaturated fatty acids, i.e. when the chance of the formation of reactive intermediates is increased. This is based on the observation of the presence of non-reducible high molecular weight collagenous material in pepsin treated collagen. This high molecular weight fraction exhibited a typical 390/460 nm fluorescence and a distinct decrease of lysine content. It is suggested that the observed phenomena result from the action of in vivo present potential cross-linking agents.

Animals↗
PubMed1981

The effect of food restriction and low protein diet upon collagen type I and III ratio in rat skin.

It has been demonstrated that the content of the collagen type I is more affected by both chronic low protein diet feeding and chronic food deprivation (50% food intake) than the content of collagen type III. By introducing these dietary regimes the proportion of collagen type I to collagen type III ratio drops from 2.1 to 1.3 indicating the higher proportion of collagen type III in the skin at the end of the experiment (after 18 months of chronic feeding). It was also observed that the total concentration of hydroxyproline (hyp) in the skin decreases considerably in both food restricted animals and those fed a low protein diet. It is suggested that, under the present experimental conditions, the balance between collagen break-down and synthesis is shifted and, furthermore, that this shift is different for collagen type I and III and results in an altered ratio of these two collagen species in the skin. Refeeding of animals leads to a higher than normal collagen type I to III ratio indicating thus a relatively higher proportion of collagen type I in this tissue.

Animals↗
PubMed1980

Studies on the chemical nature of elastin fluorescence.

Two fluorescent fractions were found in total acid hydrolysate of elastin. The fraction with higher chromatography mobility in isopropyl alcohol/conc. ammonia/water (9 : 1 : 2) was purified by multiple preparative paper chromatography in the same solvent system, and by gel chromatography on Sephadex G-25, ion-exchange chromatography on phosphocellulose and another gel chromatography on Sephadex G-10. The purified material was chromatographically homogeneous, had an ultraviolet absorption maximum at 315 nm and exhibited a strong 320/405 nm fluorescence. 1H- and 13C-NMR spectra were in good agreement with those published previously [6] for pyridinoline, a lysine derived fluorescent compound in collagen. The major part of the fluorescent material present in acid hydrolysate of elastin was always contaminated, even after complex purification procedures. It is concluded that elastin contains several fluorophores, one of which is a cross-linking tricarboxylic amino acid with a pyridinium ring having very probably the structure of 3-(2-amino-2-carboxyethyl)-1-(5-amino-5-carboxy-2-hydroxy-pentyl)-4-(3-amino-3- carboxypropyl)-5-hydroxypyridinium. The position of 2-amino-2-carboxyethyl and 3-amino-3-carboxypropyl residues has not been definitely established and can be interchanged.

Amino Acids↗
PubMed1980

Effect of cartilage bone marrow extract on the metabolism of collagen in osteoarthrotic cartilage.

The effect of cartilage bone marrow extract (CBME) on the metabolism of collagen and proteoglycan in crude embryo and human cartilage was investigated. While in chick embryos' articular cartilages the increased levels of radioactivity in collagen and proteoglycan were observed, in normal human cartilage only slight changes were detected. In osteoarthrotic cartilages, however, a marked increase in radioactivity was found in collagen and in the proteoglycan fraction containing the glycoprotein link. A blockade of collagenolysis by CBME treatment is suggested.

Animals↗