1983 Volume 20 Issue 6 Pages 459-462
Many hemoatology studies have shown that the erythrocyte count decreases while the size of the individual cell increases in the aged. However, recently, we showed there was no evidence of vitamin B12 or folate deficiency in the aged to explain the observed macrocytosis by deoxyuridine supperssion test.
This study was performed to evaluate a rate of incroporation of 3H-Thymidine into nucleated bone marrow cells with aging. Fresh bone marrow cells were obtained from 15 young (20-38yr.), 11 middle-aged (47-61yr.) and 14 elderly (70-82yr.) men. We compared the uptake of 3H-Thymidine by 4×106 bone marrow cells among these three groups. There was no signifierence between the young (66997±18672 CPM/well, mean±S.D.) and middle-aged (59048±20512) groups. However, the 3H-Thymidine uptake was significantly lower in the old age group (42339±13089), though their proportions of bone marrow cell composition were within normal limit. These results suggest that the rate of DNA synthesis of bone marrow cells is reduced in the aged, although we showed the route of deoxyuridine to thymidylate in DNA synthetic pathway in the aged was intact, using deoxyuridine suppression test, previously. The mean ratio of 3H-Uridine to 3H-Thymidine uptake of the aged men was 0.60. It was significantly higher than that of young men (0.24).
This indicates that bone marrow cells may be in a sort of unbalanced growth state in which RNA and protein syntheses continue while DNA synthesis is retarded, in the aged. The cytoplasmic component are thus excessively synthesized during the delayed cell division. Therefore erythrocytes decrease in number but increase in volume although there is no evidence of vitamine B12 and/or folate deficiency in the aged.