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Biomedical subjects

G D Gray

Publications and source records attributed to G D Gray.

At least 73 records · Page 4Linked to original sources
PubMed1977

Maternal age and male behavior in relation to successful reproduction by female rats (Rattus norvegicus).

This research demonstrated that multiple ejaculatory series may be critically important for successful reproduction by multiparous old females near the end of their active reproductive lives. Multiple series were essential for successful pregnancy, apparently because more than one series was necessary to induce functional luteal activity. Thus, (a) females receiving just one series failed to show the cessation of regular estrous cycles which characteristically follows induction of a functional luteal phase; (b) direct measurement of plasma progestins by radioimmunoassay revealed that only those females receiving more than one series had circulating levels significantly higher than unmated, normally cycling controls; and (c) administration of exogenous progesterone increased significantly the incidence of successful pregnancy among females allowed to mate through only one series. In addition to facilitating the occurrence of pregnancy, multiple series also increased both the number of eggs released at ovulation and the number of embryos present and developing 12 days later. It is concluded that multiple series may function as a behavioral mechanism for prolonging the female's active reproductive life.

Age Factors↗
PubMed1976

Nucleic acids. 16. Orally active derivatives of ara-cytidine.

Water-soluble derivatives of ara-cytidine (cytarabine, Cytosar) were prepared and tested for antitumor, immunosuppressive, and antiarthritic activities in animals after oral administration. The compounds tested included the 5'-palmitate, 5'-benzoate, and 5'-adamantoate esters of ara-cytidine, made water soluble by use of their hydrochloride salts of peptidyl derivatives, and two basic 5' esters (5'-nicotinoate and 5'-quinuclidinate) as their hydrochloride salts. Five of the compounds had antitumor activity superior to that found with ara-cytidine itself after oral administration in the L1210 leukemic mouse assay. One of these, 5'-adamantoyl-ara-cytidine hydrochloride, had antitumor activity after oral administration approaching that achieved with parenterally administered ara-cytidine.

Administration, Oral↗
PubMed1974

Inhibition by streptovaricins of Rauscher leukemia virus splenomegaly.

Streptovaricins (Sv), ansa macrolide antibiotics, inhibited Rauscher leukemia virus (RLV) splenomegaly by 25-50%. All streptovaricins tested were effective when administered orally either by diet ad lib or by intubation from infection to time of killing. When delivered by intubation, Sv was measurable in plasma for up to 6 h. SvC, at 300 mg/kg/day, reduced mean spleen weight of infected mice from 478 plus or minus 51 (SE) mg to 300 plus or minus 55 (SE) mg. Rifampicin, at 250 mg/kg/day, had no similar activity. Decrease in caloric intake and in body-weight gain also resulted in an inhibition of RLV splenomegaly; although Sv-treated mice gained weight, the increase was usually slightly less than controls. However, mice treated with a Sv diet for a week prior to infection, after an initial period of weight loss, gained at a rate equivalent to control group, and when killed had a marked reduction in splenomegaly. The selectivity of streptovaricins and specificity for viral events was suggested by several observations: (1) Splenomegaly and mortality, induced by L1210 or a non-infective transplantable tumor of RLV origin, was not inhibited. (2) No inhibition of normal hematopoietic spleen colonies was observed. (3) Host immune responses, including cellular and humoral immunity and interferon production and action, were not inhibited. Thus, although the effect of slightly decreased weight and intake could not be unequivocally established, the findings were most compatible with a selective inhibition of RLV splenomegaly by Sv.

Animals↗