Biomedical subjects

M E Shumway

Publications and source records attributed to M E Shumway.

3 recordsLinked to original sources

PubMed1991

Ascorbic acid in Drosophila and changes during aging.

The ascorbic acid content of Drosophila melanogaster was found to be high in the absence of a dietary source. The amount of ascorbic acid per fly declined with aging in both the Oregon R and Swedish C strains. The median life span at 25 degrees C was 45 days for Swedish C and 59 days for Oregon R. The amount of ascorbic acid in Swedish C flies (0.078 micrograms/fly) was higher than that for Oregon R (0.058 micrograms/fly) for newly emerged flies but the rate of decline with aging was greater for Swedish C than Oregon R. The decline in ascorbic acid content with aging was 70.4% for Swedish C versus 19.9% for Oregon R. A brief cold shock was found to significantly increase the amount of ascorbic acid in Oregon R flies. Feeding the precursor of ascorbic acid synthesis, L-gulonolactone, did not improve the life span. Life-time feeding of ascorbic acid did not improve the life span of either Swedish C or Oregon R flies.

Aging↗

PubMed1991

Uric acid content of Drosophila decreases with aging.

Free uric acid concentrations declined with aging in male Oregon R Drosophila melanogaster by 59% or more between 0 and 50 days of adult age. Free xanthine concentrations increased between 0 and 5 days of age and declined by 75% between 5 and 50 days of age. Xanthine oxidase activity was maximal for newly emerged flies and then declined rapidly reaching a minimum at 9 days of age. After 9 days of age xanthine concentrations may be the limiting factor for the production of uric acid by xanthine oxidase in aging fruit flies. Declining uric acid concentrations may represent a loss of antioxidant potential in aging Drosophila.

Aging↗

PubMed1990

Calcium, iron, copper, boron, collagen, and density changes in bone with aging in C57BL/6J male mice.

X-rays of old C57BL/6J male mice showed deformed vertebral columns. Bone density was found to increase between 76 and 517 days of age and to decrease after 685 days of age. The boron content of femurs declined by 9% with aging but the decrease was not significant. Calcium increased between 76 and 198 days of age but declined by 36% between 200 and 1000 days of age. Iron increased by 207% by 1000 days of age. Copper declined between 76 and 198 days of age but increased by 61% between 200 and 1000 days of age. Bone collagen as indicated by hydroxyproline and proline content decreased 17.4% by 1000 days of age. The largest single change with aging was, therefore, in the iron content of bone. Several correlations were found to be independent of the age of the animals. Bone density was correlated with bone calcium and collagen. Iron was negatively correlated with calcium and collagen. Calcium and collagen content were unrelated. Bone density and iron were also surprisingly unrelated. A possible explanation for this observation is given. Copper was negatively correlated with bone calcium, bone density, and collagen content. Excess copper was, therefore, the single most important factor associated with decreasing bone size and density.

Aging↗