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Biomedical subjects

K Sundaram

Publications and source records attributed to K Sundaram.

At least 127 records · Page 7Linked to original sources
PubMed1978

The effect of hycanthone and maleic hydrazide on the frequency of micronuclei in the bone-marrow erythrocytes of mice.

Male Swiss mice were assigned to 6 groups of either 3 or 4 animals each. 3 groups were given hycanthone methanesulfonate intraperitoneally, at 40, 80 or 120 mg/kg, respectively; the dose was repeated after an interval of about 24 h. At the same time 2 groups received maleic hydrazide at 100 or 200 mg/kg, and the remaining group was given dimethyl sulfoxide which was used as a solvent for both drugs. 6 h after the second injection, the mice were killed and bonemarrow preparations were made. Hycanthone induced a significant increase in the frequency of micronuclei in the polychromatic erythrocytes and suppressed the P/N ratio significantly. However, there was no dose-response relationship. Maleic hydrazide, on the other hand, failed to influence the incidence of micronuclei or the ratio of poly- to normo-chromatic erythrocytes.

Animals↗
PubMed1978

The source of progesterone in rabbit blastocysts.

High levels of progesterone were found in the blastocysts, uterine fluid and sera of normal pregnant rabbits on Days 6 and 7 of pregnancy. Very little progesterone (less than 2% of control) was present in bilaterally ovariectomized rabbits in which pregnancy was maintained by the administration of medroxyprogesterone acetate. The results demonstrate that the rabbit blastocyst is provided with large amounts of progesterone derived from the maternal ovaries.

Animals↗
PubMed1978

Suppression of primary immune response by heterologous anti-lymphocyte sera.

The effect of anti-lymphocyte serum (ALS) on the primary immune response to sheep erythrocytes (SRBC) in rats was studied by the Jerne Plaque technique. ALS against normal rat lymph node cells, ALS(N) suppressed the immune response to SRBC when administered before the antigen and had no effect on the immune response when administered either with or after the antigen. ALS(I), which was produced against lymph node cells from SRBC immunized rats, produced significant immunosuppression when administered either before or after the antigen.

Animals↗
PubMed1977

Evaluation of freshly irradiated wheat for dominant lethal mutations in Wistar rats.

Three independent, serially performed experiments involving acute and chronic feeding of freshly irradiated wheat (75 krad, gamma-irradiation) were carried out in Wistar rats. In the first experiment groups of 10 males were given wheat for 1 week; irradiated wheat was consumed by the animals within 24 h or irradiation. In the other two experiments feeding of males was continued for 6 (10 males per group) and 12 (13 males per group) weeks, respectively, and the irradiated wheat was fed within 7 days of irradiation. At the end of each treatment period each male was paired with 3 females for 7 days and sequentially at weekly intervals for 5 or 8 weeks. Females were killed and examined for live and dead implantations and corpora lutea. There were no differences between groups with regard to fertility nor was there any inter-group differences as regards pre- and post-implantation losses whether the rats were fed irradiated or non-irradiated wheat. This suggested that even feeding of freshly irradiated wheat does not induce any dominant lethal mutations in rats.

Animals↗
PubMed1977

Antitumor immunity, V.BCG-induced growth inhibition of murine tumors. Effect of hydrocortisone, antiserum against theta antigen, and gamma-irradiated BCG.

Dimethylbenzdithionsaphthene (DBDN)-induced fibrosarcoma transplantable in syngeneic Swiss mice was a weakly immunogenic tumor and did not regress spontaneously. BCG from India, when incubated with the lethal dose of DBDN-induced fibrosarcoma and subsequently inoculated sc into the susceptible animal markedly inhibited growth of the tumor. Animals that did not show any tumors developed tumor-specific immunity. BCG, if administered separately and not inoculated with the tumor cells, did not show similar response. The close contact between the BCG organism and the tumor cell seemed to be an essential requirement for BCG-induced tumor-growth inhibition. Hydrocortisone-treated animals showed tumor growth even when a BCG-tumor admixture was incorporated, indicating the immunologic nature of the phenomenon. Animals preinoculated with anti-O-serum also showed tumor growth when the BCG-tumor admixture was given. This, however, pointed out a major role of O-bearing lymmphocytes in BCG-induced-tumor-growth inhibition.

Animals↗
PubMed1976

Antitumor immunity. II. Viability, tumorigenicity, and immunogenicity of neuraminidase-treated tumor cells: effective immunization of animals with a tumor vaccine.

A dimethylbenzdithionaphthene (DBDN)-induced fibrosarcoma showed reduced transplantability if previously treated with Vibrio cholerae neuraminidase (VCN). However, the reduced transplantability of VCN-treated tumor cells was not associated with any loss of their viability or tumorigenic capability, but appeared to be due to their increase in immunogenicity. High doses of VCN-treated tumor cells could grow even in normal individuals. Lower doses, which did not induce tumor development in normal individuals, did so if injected into immunosuppressed animals. Although X-irradiation of VCN-treated tumor cells reduced their tumorigenic potential, it did not impair their increased immunogenic properties. Thus a suitable method for the preparation of a "tumor vaccine" was provided. The immunization of animals with the vaccine and a working hypothesis regarding its mechanism of action were described.

Animals↗
PubMed1976

Reversible inhibition of ovulation in the rhesus monkey by polydimethylsiloxane subdermal capsules of megestrol acetate.

The effect of megestrol acetate in polydimethylsiloxane subcutaneous implants on menstrual cycle, ovarian function, and uterine histology of adult parous rhesus monkeys was studied. Release rates of 129.6 and 64.8 mug/day inhibited ovulation and produced amenorrhea in all of the treated monkeys. The plasma progesterone level was 0 ng/ml during the initial part of the study (8 months). Endometrial biopsies obtained at different times showed a suppressed endometrium. Approximately 30 days after removal of all of the polydimethylsiloxane implants, the monkeys menstruated normally and the plasma progesterone levels subsequently were between 3 and 19 ng/ml. Histologic studies showed secretory endometria and corpora lutea, thus confirming resumption of ovulation.

Animals↗