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Biomedical subjects

P K Ray

Publications and source records attributed to P K Ray.

At least 145 records · Page 8Linked to original sources
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↗
PubMed1975

Effect of concanavalin A and phytohemagglutinin on the modification of immunogenicity of canine kidney allografts.

Mongrel dog kidneys were allografted to unrelated nephrectomized recipients which were then treated with subimmunosuppressive doses of azathioprine (2.5 mg/kg/day). Dog kidneys treated in vitro with perfusates containing concanavalin A (Con A) or phytohemagglutinin-P (PHA) survived as long as 60 days (mean 39.8 +/- 4.3) after transplantation, whereas normal kidneys survived less than 16 days. The optimal prolongation was achieved by perfusing the kidneys with 500 ml Ringer's lactate containing 25 mg/L Con A, 25 4 degrees C. Lesser effects were achieved with higher or lower concentrations of Con A, or with perfusions carried out at 25 degrees C. Most evidence suggests that Con A and PHA bind to cell surfaces and interfere with the perception of the graft antigens by the host.

Animals↗
PubMed1975

Response of solitary adrenal gland to surgical stress.

Available reports on adrenal function following unilateral adrenalectomy mainly concern the gland's activity under basal conditions. Its response to superadded stress has largely escaped attention. The present communication deals with changes in morphology and in the behavior of acid phosphatase, non-specific esterases and 3beta-hydroxysteroid dehydrogenase in solitary adrenal glands following operative trauma. Histochemical, electrophoretic and biochemical techniques have been employed in the study. Although the morphological response to identical trauma on both unilaterally adrenal-extomized and intact animals is indistinguishable, the enzymological response is strikingly different in the two groups. While in the latter, the enzyme activities exhibit an early rise following trauma, the same is delayed by another 8 hr in the former. In experments using ACTH, the overall pattern of exterase activity shows little deviation from that observed in untreated cases in both groups of animals. The findings indicate that in unilaterally adrenalectomized animals, susperadded operative stimuli fail to evoke the early response characteristic of the normal adrenal glands. Such latency points to the vulnerability of their existing defence mechanisms. The remarkable similarity of adrenal response with or without exogenous ACTH in these animals suggests that the reason for a delayed response is rooted in the target organ itself, and is not due to an altered plasma ACTH level.

Acid Phosphatase↗
PubMed1975

Cytolysis of neuraminidase-treated autochthonous lymphoid cells by autologous serum.

Rabbit lymph node cells treated with bacterial neuraminidase become susceptible to cytolysis by autologous antibody and complement. Cytolysis of cells can be prevented by absorbing out the antibodies, probably IgM antibodies, from the autologous serum using neuraminidase-treated autochthonous lymph node cells. The significance of this mechanism is discussed.

Absorption↗
PubMed1973

A modified whole blood partial thromboplastin test for the assessment of heparinization.

Current methods of assessment of heparinization are either inconvenient as bedside procedures or lack correlation with the Lee-White whole blood clotting time over the therapeutic range. A new thromboplastin time (CAT time) has been developed to overcome these disadvantages by offering uniform contact activation. The test makes use of a partial thromboplastin activated by celite-adsorbed "contact factor", thus eliminating the activation phase of the activated partial thromboplastin time. Preliminary experiments suggest that this modification will be helpful in the study of "contact factor" deficiencies.

Blood Coagulation Tests↗