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Biomedical subjects

M Menon

Publications and source records attributed to M Menon.

At least 181 records · Page 10Linked to original sources
PubMed1979

Deae-dextran and T-cell rosette formation.

Use of DEAE-dextran (a polycation) increases and stabilizes the rosettes formed between sheep red cells and human peripheral blood lymphocytes. Under its influence, reproducible stable rosettes are formed after one hour of incubation in an ice bath instead of the usually required 18 to 24 hours. We have shown that rosettes are specific for T-cells and not due to "co-rosetting" of nonrosette forming cells into the T-cell rosette clusters. Only the cells from normal controls consistently show an increase in rosette formation hence routine use of this 'stabilizer' in clinical immunology is not recommended.

Adult↗
PubMed1979

Consideration and implications of tumor antigenic expression.

This review is an attempt to simplify the myriad descriptions of tumor antigens, by considering such antigens in the perspective of their mechanisms of formation. We believe that most and possibly all tumor antigens previously described and currently under study will ultimately fit into one of the categories discussed in this article, since there are only a finite number of biochemical mechanisms for producing new antigens in any cell--cancerous or otherwise. Pragmatically, we view the vagaries of expression of tumor antigens as among their most important properties, and the search for tumor antigens has in fact opened a Pandora's box of molecular variability. Large tumor masses consisting of multiple subclones with different karyotypes, chromosomal anomalies and mutations would appear to be capable of expressing a motley group of tumor antigens. To the best of our knowledge, no tumor antigen has been shown to be necessary and causal in transformation, except in virally-induced tumors. The presence of tumor antigens appears to be coincidental and reflects dedifferentiation and karyotypic, metabolic and nutritional variations occurring in tumors. Undoubtedly, some antigens may give a tumor a selective advantage of growth, metabolism or metastatic potential, but many antigens may simply reflect the vagaries of the tumor cell. The intratumor and intertumor variations of tumor antigens, their mechanisms of origin and their rather uncanny capabilities to change their phenotype--antigen expression--secondary to environmental selection during tumor expansion or following therapy should be kept in mind when tumor antigens and immunotherapy are considered.

Animals↗
PubMed1978

Cell-mediated immune competence in patients with prostatic carcinoma.

The immune competence of 65 patients with prostatic cancer was evaluated by 2 in vivo and 2 in vitro tests to study the contribution of host factors to the progress of the disease. Patients with benign prostatic hypertrophy served as controls. Our results indicate that the delayed skin hypersensitivity response to common microbial recall antigens (streptokinase/streptodornase, purified protein derivative, dermatophytin 0 and dermatophytin) is unaltered in advanced stages of malignancy. The ability to be sensitized by dinitrochlorobenzene declines significantly in patients with metastatic disease. Blastogenic response of peripheral blood lymphocytes to phytohemagglutinin stimulation is not depressed in late stages of malignancy, although in the circulating T cells per cent and absolute values are somewhat lower in patients with metastases. Herein we show that immune competence (measured by the 4 tests) of patients with prostatic carcinoma does not decrease markedly even in the late stages of the disease. Primary sensitization to dinitrochlorobenzene is the only test showing a decline in responsiveness related to the tumor stage.

Carcinoma↗
PubMed1978

Changes in pheromone production, release, mating behaviour and reproductive ability of the gamma-irradiated cockroach Nauphoeta cinerea (Olivier).

Mature males of Nauphoeta cinerea produce a sex pheromone 'seducin' which has short-range effects in attracting mature females of the same species. Exposure of newly-emerged adult males to 3.5, 7, 14 or 21 krad of gamma-radiation decreased their life expectancy and affected their mating behaviour. Bioassay of dichloromethane extracts of males showed that radiation doses (14 krad) sufficient to induce sterility did not affect the ability to produce pheromone but significantly reduced the release of pheromone by inhibiting wing-raising. The sterile-male technique using males sterilized by ionizing radiation in air may not be the method of choice for control of Nauphoeta cinerea.

Animals↗
PubMed1978

Lymphocyte mediated natural cytotoxicity in neoplasia.

Peripheral blood lymphoid cells from normal donors, patients with non-malignant diseases, and patients with malignant diseases were evaluated for cytotoxicity against a cultured carcinoma cell line, using a chromium release assay. The natural spontaneous lymphocyte-mediated cytotoxicity was significantly higher in tumor-free groups. The observed decreased response in patients with malignancies correlated with depressed responsiveness to phytohemagglutinin stimulation. Removal of cell subpopulations bearing Fc receptors significantly decreased the cytotoxicity, while depletion of phagocytic mononuclear cells did not. We suggest that natural cytotoxicity is a measure of cell membrane integrity of lymphocytes and should be included as a routine test for evaluation of general immune competence.

Adolescent↗
PubMed1978

Characterization of the binding of a potent synthetic androgen, methyltrienolone, to human tissues.

The potent synthetic androgen methytrienolone (R 1881), which does not bind to serum proteins, was utilized to characterize binding to receptors in human androgen responsive tissues. Cytosol extracts prepared from hypertrophic prostates (BPH) were utilized as the source of receptor for the initial studies. High affinity binding was detected in the cytosol of 29 of 30 samples of BPH (average number of binding sites, 45.8+/-4.7 fmol/mg of protein; dissociation constant, 0.9+/-0.2 nM). This binding had the characteristics of a receptor: heat lability, precipitability by 0-33% ammonium sulfate and by protamine sulfate, and 8S sedimentation coefficient. High affinity binding was also detected in cytosol prepared from seminal vesicle, epididymis, and genital skin but not in non-genital skin or muscle. However, similar binding was demonstrated in the cytosol of human uterus. The steroid specificities of binding to the cytosol of male tissues of accessory reproduction and of uterus were similar in that progestational agents were more effective competitors than natural androgens. Binding specificities in cytosol prepared from genital skin were distinctly different and were similar to those of ventral prostate from the castrated rat in that dihydrotestosterone was much more potent than progestins in competition. Thus binding of R 1881 to the cytosol of prostate, epididymis, and seminal vesicle has some characteristics of binding to a progesterone receptor. When the nuclear extract from BPH was analyzed, high affinity binding was demonstrated that conformed to the specificities of binding to an androgen receptor. Here dihydrotestosterone was a more potent competitor than progestational agents. Similar patterns of binding were detected in the crude nuclear extracts from seminal vesicle, epididymis, and genital skin but not in uterus, muscle, or non-genital skin. We conclude that the androgen receptor is not demonstrable in the cytosol of prostate, epididymis, or seminal vesicle of non-castrated men but can be measured in the cytosol of genital skin and the nuclear extracts of androgen responsive tissues. Because steroid hormones exert their major influence within the nucleus of target tissues, the measurement of nuclear receptor may provide valuable insight into the regulation of growth of target tissues.

Cytosol↗
PubMed1977

Demonstration of the existence of canine prostatic lymphatics by radioisotope techniques.

Radioactive 198Au colloid injected into the canine prostate through an opened bladder to avoid violating the prostatic capsule was observed to migrate from the prostate to the regional lymph nodes. Significant isotope uptake in the kidney, liver, rectus muscle and distant lymph nodes was not detected, thus indicating direct spread of the isotope to the regional lymph nodes.

Animals↗
PubMed1977

The measurement of androgen receptors in human prostatic tissue utilizing sucrose density centrifugation and a protamine precipitation assay.

Methods have been established for the measurement of androgen receptors in the cytosol and crude nuclear extract of human prostatic tissue using sucrose density gradient centrifugation and a protamine precipitation assay. These studies have demonstrated the presence of a high affinity, heat labile protein that binds preferentially to dihydrotestosterone and that is present only in androgen target tissues. In studies of prostatic tissue from 15 patients sucrose density gradient centrifugation appeared more sensitive than the protamine precipitation assay in the identification of androgen receptors. These findings appear promising and suggest that in the near future a reliable assay may be available for the measurement of androgen receptors in prostatic carcinoma.

Centrifugation, Density Gradient↗
PubMed1977

The binding of a potent synthetic androgen--methyltrienolone (R 1881)--to cytosol preparations of human prostatic cancer.

The binding of 3H-R 1881 to cytosol prepared from benign and malignant prostatic neoplasms has been investigated. We have demonstrated that high affinity binding of 3H-R 1881 is present in cytosol preparations of benign prostatic hyperplasia, in specimens of prostatic cancer obtained from patients prior to hormonal therapy and in carcinoma of the prostate metastatic to lymph nodes. In addition, high affinity binding was present in all specimens of prostatic cancer from patients who had objective evidence of progressive metastatic disease after an initial response to hormonal therapy. Until greater numbers of patients have been studied the significance of these findings can only be speculative. Because the binding of 3H-R 1881 may measure androgen and progesterone receptors future investigations must include careful steroid specificity studies. Finally, because steroidal hormones exert their major influence within the nucleus of target tissues the measurement of nuclear receptor content may provide a more accurate means to predict the hormonal responsiveness of prostatic cancer.

Animals↗