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Biomedical subjects

M Schechter

Publications and source records attributed to M Schechter.

At least 109 records · Page 6Linked to original sources

Enhanced lymphocyte-mediated killing of tumour cells after tumour irradiation in vivo.

The effect of local X-irradiation of a syngeneic carcinoma of fibrosarcoma growing in the leg of W/Fu rats on the ability of host spleen lymphocytes to kill syngeneic and allogeneic tumour cells in vitro was examined. Lymphocytotoxicity was found to be enhanced one day after local X-irradiation (4000 R) when compared with unirradiated tumour-bearing rats (p = 0.05 to 0.01). This enhancing effect of local irradiation was not observed when the lymphocytes were tested 1 week or later after X-irradiation, nor when normal legs of non-tumour bearing rats were irradiated. Mechanisms which might possibly explain these results are a reduction in release of tumour-specific antigen which can act as an inhibitor of cell-mediated cytotoxicity, or depletion of suppressor cells in the lymphocyte population. These findings may be relavant to clinical studies of cellular immunity in patients undergoing radiotherapy of malignant tumours.

Animals↗

Effects of hyperthermia on primary and metastatic tumor growth and host immune response in rats.

A hot water bath was used to heat locally a metastasizing carcinoma in Wistar/Furth rats. Applying heat such that intratumor temperature is maintained at a mean value of 42.3 degrees for two 90-min sessions results in a decreased growth rate of the primary tumor as well as distant metastases. Heating the primary tumor for only one 90-min session or heating the leg contralateral to the tumor-bearing limb has no effect on the growth rate of either the primary tumor or metastases. Heat therapy has no detrimental effect on the spleen cell-mediated tumor immune response of rats as tested by an in vitro lymphocytotoxicity assay 1 day later. However, heating isolated spleen cells to similar temperatures in vitro reduces their capacity for in vitro tumor cell killing.

Animals↗

Treatment of rat fibrosarcoma by radiotherapy plus immune adjuvant.

Combined radiotherapy and nonspecific adjuvant C. parvum or Piromen treatment of rat tumors show improvement over radiotherapy alone. The most effective protocol, resulting in complete remission in 6 of 6 rats was obtained with C. parvum given i.p. in three doses 1 day prior to tumor X-irradiation of three doses of 1500 R each given on days 1, 4, and 8. Animals receiving the same dose schedule without adjuvant had only partial regression of their tumor. Without adjuvant, increasing the dose to 6000 R also resulted in tumor regression, but at the expense of marked necrosis to the leg. One mechanism for the observed results may be stimulation of the reticulo-endothelial system to produce macrophages activated against the tumor. It is also possible that C. parvum causes increased rate of clearance of soluble antigens released as a result of radiation destruction of the tumor, as suggested by Proctor et al (3).

Adjuvants, Immunologic↗

Diaper deaths.

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Humans↗

Antibiotic regimen as an independent risk factor for disseminated fungal infections in neutropenic patients in Brazil.

In a cohort of 79 febrile episodes in 50 consecutive neutropenic patients seen at the University Hospital, Federal University of Rio de Janeiro, Brazil, between 1987 and 1991, it was observed that the cumulative incidence of disseminated fungal infections rose from 3% to 19% after the introduction of a new empirical antibiotic regimen. In order to identify risk factors, as well as to assess the impact of the new antibiotic regimen on the emergence of fungal infections, a nested case-control study was undertaken, in which 10 cases of disseminated fungal infections were compared with 30 randomly chosen controls, drawn from the same cohort. In a multiple logistic regression analysis, the predictive factors for disseminated fungal infection were younger age (odds ratio 0.85, 95% confidence interval 0.75-0.97) and use of the new antibiotic regimen (odds ratio 14.18, 95% confidence interval 1.05-191.80) The probable explanation for the emergence of fungal infections is that the new antibiotic regimen, by lowering the incidence of bacteraemia-related deaths, allowed patients to be at risk for the development of disseminated fungal infections.

Adolescent↗

Evaluation of a monoclonal antibody affinity purified antigen for zymodeme specific serological diagnosis of Trypanosoma cruzi infection.

Theoretically, serological assays with affinity purified marker antigens can allow strain-specific diagnosis even when parasites cannot be retrieved from an infected host. A Trypanosoma cruzi antigen was purified by affinity chromatography using a zymodeme (Z) 2 specific monoclonal antibody (2E2C11). An indirect enzyme-linked immunosorbent assay (ELISA) based on the purified antigen could discriminate between sera from rabbits immunized with T. cruzi zymodeme clones but could not discriminate between sera from mice infected with different zymodemes.

Animals↗