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Biomedical subjects

D B Thomas

Publications and source records attributed to D B Thomas.

At least 289 records · Page 16Linked to original sources
PubMed1970

The effects of x-irradiation and anti-lymphocyte serum on the responses to tumour allografts.

The growth of a CBA mammary adenocarcinoma has been studied following transplantation to syngeneic and allogeneic recipients, with particular reference to the susceptibilities of the primary and secondary responses elicited by the tumour allografts, to impairment by whole-body X-irradiation and by treatment with rabbit-anti-mouse lymphocyte serum. In syngeneic recipients, the diameter of tumour implants increases linearly with time and there is no difference in the growth curves in females and in males. Later tumour generations grow faster than earlier generations. In allogeneic recipients, there is a relationship between the tumour diameter on day 21 (T) and the dose of X-irradiation (D) administered before implantation:T = 0.028 D - 9.17for early tumour generations (SMT4) but this is obscured for later generations (SMT21). The primary response to tumour allografts was radiosensitive whereas the secondary response was radioresistant. This radioresistance of the secondary response persisted for at least 5 months after primary sensitization. Unlike whole-body X-irradiation, treatment with rabbit-anti-mouse lymphocyte serum suppresses both the primary and secondary responses to tumour allografts. The possibility is considered that after exposure to antigenic stimulation, an immunologically reactive cell population is formed which is radioresistant but sensitive to ALS, unlike the precursor cells from which this population is derived, which are radiosensitive and sensitive to ALS.

Adenocarcinoma↗
PubMed1969

Vitamin A and the biosynthesis of sulphated mucopolysaccharides. Experiments with rats and cultured neoplastic mast cells.

1. The uptake and incorporation of [(35)S]sulphate into mucopolysaccharides by colon and duodenum in vitro are unaffected by the vitamin A status of the animals. 2. Uptake and incorporation in vivo are unaffected at 4hr. after injection of [(35)S]sulphate, but at later times are decreased in some tissues of vitamin A-deficient animals. 3. The rate of removal of (35)S from blood, its rate of appearance in urine, the plasma concentration of sulphate and the uronic acid content of several tissues are not significantly altered in vitamin A deficiency. 4. These results, and direct measurement of (35)S in mucopolysaccharides at various times after injection of [(35)S]sulphate, suggest that the synthesis of mucopolysaccharides is unaffected but that their turnover is increased in vitamin A deficiency. 5. Neither the growth rate of, nor the incorporation of [(35)S]sulphate into heparin by, P815Y and HC cultured neoplastic mast cells is decreased when the horse serum necessary for growth is treated with ultraviolet light or is replaced by serum from vitamin A-deficient rats. 6. The addition of citral is no more toxic to growth rate or to incorporation of (35)S than is the addition of vitamin A itself. 7. It is concluded that neoplastic mast cells in culture do not require vitamin A for growth or for the synthesis of heparin. 8. None of these results is compatible with the view that vitamin A or a derivative is directly involved in the biosynthesis of sulphated mucopolysaccharides.

Aldehydes↗