Biomedical subjects

G Fosmire

Publications and source records attributed to G Fosmire.

3 recordsLinked to original sources

PubMed1994

Variations in plasma zinc in older men and women.

The study evaluated the biological and analytical variance in plasma zinc from 36 adults 60-88 yr of age. Blood samples were taken by finger-prick from each subject on d 1, 2, 3, 8, and 15. Days 1, 2, and 3 were selected to describe daily variation; 1, 8, and 15 were selected to describe weekly variation. Plasma Zn was analyzed by flame atomic absorption using a microinjection technique. Variation was partitioned into analytical, intraindividual, and interindividual components using analysis of variance. The interindividual variability was generally greater than the intraindividual variability. The variability for plasma zinc was about 30% and was substantially greater than reported for younger populations. This variability could not be attributed to the covariates examined, including zinc intake from food and supplements, serum albumin, and C-reactive protein. The variability would affect the accuracy of plasma zinc status based on a blood sample collected on a single day. With the microtechnique used in this study, 8 sample days would be needed to estimate plasma Zn with 95% confidence level and 20% level of accuracy.

Age Factors↗

PubMed1982

Effects of moderate zinc deficiency on cognitive performance in young adult rats.

Two experiments were conducted to establish a dietary zinc level which approximates a moderate deficiency in the young adult rat and to determine if a concurrent zinc deficiency affects cognitive performance. Male rats were fed varying levels of zinc in diet throughout a 17-day period. The lowest dietary level that depressed serum and bone zinc without influencing food consumption or body weight gains was observed to be 5.8 microgram Zn/g diet. Young adult rats maintained on either a zinc adequate (24.4 microgram Zn/g) or low-zinc (5.3 microgram Zn/g) diet were tested in a modified Skinner Box involving tests of visual, auditory, association, and discrimination learning. No differences were observed in the visual discrimination performance of the zinc deficient animals when compared with control counterparts. Deficits in the ability to transfer a learned association between visual and auditory stimuli were observed, however, in the deficient group during the transfer test phase. The latter performed better during the final auditory discrimination task in transferring a learned food-relevant cue.

Animals↗

PubMed1978

Low pH dimerization of chymotrypsin in solution.

The mechanism of the acid dimerization of alpha-chymotrypsin in solution was reexamined using a number of chemical derivatives. Blocking of the carboxyl of Tyr-146, while that of ASP-64 remained free, eliminated completely the ability of alpha-chymotrypsin to dimerize, as did methylation of His-57. O-Acetylation of Tyr-146 reduced the dimerization constant to that of gamma-chymotrypsin, and deacetylation of the other accessible tyrosines did not affect the dimerization. It is concluded that the mechanism proposed by Aune and Timasheff [Aune, K.C., and Timasheff, S.N.(1971) Biochemistry 10, 1609-1617] for the solution dimerization which involves the electrostatic interaction between the His-57 imidazolium ring and the terminal carboxyl of Tyr-146 is still most consistent with all the experimental observations. The interactions in dilute solution may differ somewhat from those observed in crystals. In particular, the two intermolecular bridges formed by sulfate ions in crystals cannot be present in solution.

Acetylation↗