Biomedical subjects

A T Tsin

Publications and source records attributed to A T Tsin.

48 records · Page 3Linked to original sources

PubMed1985

Distribution of retinoids in different compartments of the posterior segment of the rabbit eye.

Using high-performance liquid chromatography, the amounts of all-trans retinol, retinal and retinyl palmitate were measured in the following ocular tissues and fluid of the light (LA) and dark adapted (DA) rabbit: cytosol and membrane fractions of the retina (R/C and R/M), cytosol and membrane fractions of the retinal pigment epithelium (RPE/C and RPE/M), subretinal fluid collected from the inter-photoreceptor matrix (S/R) and the matrix between apical microvilli of the RPE (S/RPE). The total amount of all-trans retinol extracted from LA eyes, 2.74 nmol per eye, was ten times greater than the amount extracted from DA eyes. In the LA eye, most of the all-trans retinol was extracted from the membrane fraction of the retina (67%); in the DA eye, most of the retinol was extracted from the cytosol fraction of the retina (58%). In contrast, the DA eye yielded more all-trans retinal (9.84 nmol) than the LA eye (5.80 nmol) and most of this retinoid was recovered from the cytosol and membrane fractions of the retina. A higher amount of all-trans retinyl palmitate was recovered from the LA eye (5.88 nmol) than the DA eye (2.02 nmol). Although most of this retinyl palmitate was extracted from the cytosol fraction of the RPE (45%, LA eye), appreciable amounts were found in all other ocular compartments. The amount of retinyl palmitate in the LA eye exceeded that of the DA eye in every compartment examined in the present study, suggesting a possible important role of retinyl esters in the visual cycle.

Animals↗

PubMed1985

Comparison of the FeKal CON-Trate system with the formalin-ethyl acetate technique for detection of intestinal parasites.

The ability of the FeKal CON-Trate system (Trend Scientific, Minneapolis, Minn.) to recover parasite ova, cysts, or larvae from 300 fecal specimens was compared with that of the Formalin-ethyl acetate sedimentation technique. One hundred stool samples had previously been determined to contain 129 parasite forms. The FeKal system detected 127 parasites (sensitivity, 98.4%), and the Formalin-ethyl acetate sedimentation technique detected 125 parasites (sensitivity, 96.9%). Higher counts of parasite forms were obtained for 11 of 14 species of parasites in specimens prepared by the FeKal system. Four specimens were negative by the Formalin-ethyl acetate method and two by the FeKal system. These false-negative observations occurred in specimens with low counts of parasites. There were no false-positive results.

Acetates↗

PubMed1984

Use of high-performance liquid chromatography in the analysis of retinyl and 3,4-didehydroretinyl compounds in tissue extracts of bullfrog tadpoles and goldfish.

HPLC (high-performance liquid chromatography) was used to analyse retinyl and 3,4-didehydroretinyl compounds in tissue extracts from goldfish and bullfrog tadpoles. Using silica columns (packed with 10-micron mu Porasil or 5-micron Ultrasphere particles) eluted with n-hexane (containing a small amount of dioxane or diethyl ether), the authentic all-trans retinyl and 3,4-didehydroretinyl palmitates, retinal and 3,4-didehydroretinal, retinol and 3,4-didehydroretinol were completely separated. Liver and eye extracts of the goldfish and bullfrog tadpoles had mainly esterified all-trans retinol and all-trans 3,4-didehydroretinol. In the liver, these vitamin A were conjugated to a number of fatty acids whereas in the eye, principally one fatty acid was used. Moreover, the relative proportions of all-trans retinol and all-trans 3,4-didehydroretinol (obtained by analysing the saponified esters) were significantly different between some of these body compartments.

Animals↗

PubMed1983

Selective utilization of vitamins A1 and A2 by goldfish photoreceptors.

The rhodopsin/porphyropsin (visual pigment) ratios in the goldfish retina were induced to change over a 300-day treatment period of specified light and temperature conditions. A concomitant but much slower change in the ratios of retinyl/3-dehydroretinyl ester in the pigment epithelium (RPE) was observed. If the changes in the visual pigment ratios were dependent on the nonselective sequestering of chromophores from the RPE ester pool, then the visual pigment changes might mirror those of the esters in the RPE. However, the relatively greater rate of visual pigment changes compared to that of the RPE esters suggests that goldfish photoreceptors synthesize their visual pigment from a relatively small pool of chromophore precursor rather than from the overall pool of retinyl and 3-dehydroretinyl esters stored in the RPE.

Animals↗

PubMed1982