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Biomedical subjects

J Gross

Publications and source records attributed to J Gross.

At least 505 records · Page 28Linked to original sources
PubMed1966

Conversion of carotenoids into vitamins A(1) and A(2) in two species of freshwater fish.

1. Examination of two zooplankton species predominating in fish ponds, Daphnia magna and Chironomus larvae, revealed the presence of alpha- and beta-carotene, echinenone, canthaxanthin and 3-hydroxy-4-oxo-beta-carotene in Daphnia, and beta-carotene and cryptoxanthin ester in Chironomus. No specific provitamins A(2) (containing a 3,4-dehydro-beta-ionone ring) were detected. 2. Guppies (Lebistes reticulatus) and platies (Xiphophorus variatus) were found to form vitamin A from beta-carotene and from its oxygen-containing derivatives isozeaxanthin, canthaxanthin and astaxanthin. Slight conversion into vitamin A(2) seemed to occur simultaneously. 3,4-Dehydro-3'-hydroxy-beta-carotene formed little vitamin A, and the latter was mainly of the A(2) type. Lutein was devoid of provitamin A properties. 3. In addition to vitamin A, beta-carotene was detected in fish receiving the 4-oxo- and 4-hydroxy-carotenoids. A reaction scheme for the conversion of carotenoids into retinal and and 3,4-dehydroretinal is presented. 4. It is concluded that natural 4-oxo derivatives of beta-carotene may play a significant role as vitamin A precursors for fish.

Journal Article↗
PubMed1958

Studies on the formation of collagen. III. Time-dependent solubility changes of collagen in vitro.

Precipitation (or gelation) of collagen from cold neutral salt solution induced by warming was shown to be reversible on subsequent cooling. The degree of reversibility of heat precipitation rapidly diminished with time of incubation at 37 degrees C. For calf skin collagen (acetic acid-extracted) and guinea pig skin collagen (crude NaCl extract) in neutral salt solutions (Gamma/2 = 0.45) roughly 90 per cent of newly formed gel redissolved on cooling at 2 degrees C.; less than 20 per cent redissolved on cooling gels previously maintained at 37 degrees C. for 24 hours. At physiologic ionic strength the same preparations exhibited much more rapid development of irreversible precipitation, but the same time dependence was clearly evident. Highly purified collagen from crude saline extracts of guinea pig skin exhibited the same phenomenon although the quantitative aspects were somewhat different.

Animals↗