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Biomedical subjects

B J Lin

Publications and source records attributed to B J Lin.

At least 73 records · Page 4Linked to original sources
PubMed1980

Quantitative correlation between the reduction of nitroblue tetrazolium and the oxygen uptake of corneal cells.

We wished to measure the amount of reduced nitroblue tetrazolium (NBT) formed in corneal cells and to relate it to the viability of the cells in terms of their oxygen uptake. Two full-thickness corneal discs of identical size (3, 4, 5 or 6 mm in diameter) were cut from the eyes of guinea pigs. One disc was processed for the measurement of its reduced NBT and cellular nitrogen content; the other was processed for the measurement of its oxygen uptake and deoxyribonucleic acid (DNA) content. As the diameter of the corneal disc (that is, the number of cells) increased, the quantity of reduced NBT, nitrogen and DNA and the oxygen uptake increased proportionality. Since each of these measures correlated positively with each other (P less than 0.01) we were able to estimate the number of viable cells in a given cornea by measuring the amount of reduced NBT (formazan granules) formed in the cells.

Animals↗
PubMed1979

Glucose oxidation in fresh guinea pig cornea.

The rate of glucose oxidation of fresh corneas of guinea pigs at different ages has been determined. Full-thickness corneal discs, 4 mm in diameter, were incubated in radioactive glucose solution. The quantity of the released CO2 was expressed in terms of the corneal discs, their dry weights, and DNA and protein contents. The rate of glucose metabolized to CO2 per hour was about 300 pmol/microgram DNA for guinea pigs weighing approximately 800 g. Glucose oxidation decreased as the age of the animals increased. Our results compared well with those obtained in other species. We therefore feel that the guinea pig should be a suitable model for research on the metabolism of corneas.

Animals↗
PubMed1979

Does the number of cells in the cornea decrease with age? A biochemical study.

We used biochemical techniques to investigate whether the cornea becomes more acellular with age. Guinea pigs of different body weights (age) were killed. From each cornea, a central full-thickness button (4 mm in diameter) was punched out. The DNA content of the corneal buttons was determined. Using spleen cells, the DNA content per diploid cell of guinea pig was also estimated. It was found that as the body weights of the animals increased, the amount of DNA per corneal disc decreased. This indicated that as the animal grows older the total cellular content of the cornea is reduced.

Aging↗
PubMed1979

Biochemical analysis of the cornea stored in steroid medium.

We wished to measure changes in the tissue mass and the deoxyribonucleic acid and protein content of guinea pig corneas stored for up to 21 days in tissue culture medium with or without 1 microM hydrocortisone. Full-thickness discs 4 mm in diameter were cut from the corneas for measurement of the three variables. Whether the disc came from a steroid-treated cornea or not, and whether it came from a fresh cornea, hydrocortisone did not appear to have any adverse effect on the features studied.

Animals↗
PubMed1978

Electroncytochemical and biochemical demonstration of guanylate cyclase activity in the pancreatic islet.

With a cytochemical method using guanylyl imidodiphosphate as a substrate, the guanylate cyclase activity was localized on the plasma membrane of A, B and D cells of islets of Langerhans isolated from the rat. Adequate control experiments were performed by a double-blind method. Parallel biochemical assay showed that guanylate cyclase activity was not completely lost after fixation with 1% glutaraldehyde and incubation with 4 mM lead nitrate. Furthermore, the depressed activity was still stimulatable with acetylcholine.

Acetylcholine↗
PubMed1977

An apparent inhibition of insulin biosynthesis resulting from inhibition of transport of neutral amino acids by arginine.

At concentrations higher than 10 mM, the cationic amino acid, arginine, inhibited the incorporation of neutral amino acids such as alanine, threonine, valine and leucine into insulin in the presence of glucose. This inhibitory effect probably did not result from the stimulatory effect of argnine on insulin release because, in the absence of glucose, arginine failed to stimulate insulin release but nevertheless inhibited the incorporation of leucine into insulin. This inhibitory effect of arginine was shared by another basic amino acid, histidine, but not by lysine. Arginine inhibited the incorporation of leucine not only into insulin but also into other islet proteins. This inhibition was not accompanied by any disturbance of glucose metabolism in the islet cells. Further studies indicated that the inhibition of incorporation resulted primarily from the interference of uptake of the neutral amino acids by arginine.

Alanine↗
PubMed1977

Differential effect of D-glucose anomers on proinsulin biosynthesis by the pancreatic islets.

Pancreatic islets of Langerhans of the rat were used to study effects of D-glucose anomers on the incorporation of [3H]leucine into proinsulin and other islet proteins. At low (1 mg/ml), but not at high (2 mg/ml) glucose concentration, the alpha-anomer stimulated more proinsulin biosynthesis than the beta-anomer. This observation adds to the growing list of islet functions showing anomeric preference for alpha-D-glucose.

Animals↗