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M Ramanarayanan

Publications and source records attributed to M Ramanarayanan.

18 recordsLinked to original sources
PubMed1997

Differential ability of T cell subsets to undergo activation-induced cell death.

Human T cell clones were analyzed for their susceptibility to activation-induced cell death (AICD) in response to CD3/T cell receptor ligation. AICD was observed only in Th1 clones and was Fas-mediated, whereas Th2 clones resisted AICD. Analysis of a panel of Th0 clones, characterized by their ability to secrete both Th1 and Th2 cytokines, revealed that this subset included both AICD-sensitive (type A) and -resistant (type B) clones. Resistance to AICD by Th2 and Th0-type B clones was not due to lack of expression of either Fas receptor or its ligand. Paradoxically, the AICD-resistant clones were susceptible to apoptosis when Fas receptor was directly ligated by anti-Fas antibodies. However, prior activation of the resistant clones by monoclonal antibodies to CD3/TCR complex induced resistance against Fas-mediated apoptosis. Thus, the Fas-FasL pathway is critical for the induction of AICD in T cells, and moreover this pathway can be negatively regulated in the AICD-resistant clones by signals that are generated from ligation of the CD3/TCR complex.

Antigen-Presenting Cells↗
PubMed1984

Immunocytochemical localization of lysozyme and alpha-1-antichymotrypsin in the term human placenta: an attempt to characterize the Hofbauer cell.

The intracellular localization of lysozyme (LSZ) and alpha-1-antichymotrypsin (A1Ac), glycoproteins associated with macrophages, was used to confirm the monocytic lineage of the Hofbauer cell and to assess the maturity of its macrophage function. The peroxidase-labeled antigen method was used to localize these proteins, as well as immunoglobulins, light chains, and albumin, in Bouin-fixed, paraffin-embedded sections of 24 normal term placentas. The demonstration of the latter substances was used as an indication of passive diffusion or phagocytosis of serum proteins resulting in intracellular localization unrelated to synthesis. In all the placentas examined a strong cytoplasmic reaction for A1Ac was seen in the Hofbauer cells. The same cells on adjacent sections did not stain for LSZ, while the occasional maternal macrophage and numerous polymorphonuclear leukocytes in the intervillous spaces gave a positive reaction. The detection of A1Ac supports the contention that these cells are macrophages, previously suggested by their phagocytic capability and the demonstration of Fc receptors and nonspecific esterases. Since they do not appear to contain LSZ, a bactericidal enzyme, we propose that these cells are not fully differentiated macrophages, and the lack of this enzyme may have some relevance to the pathogenesis of certain placental infections.

Chymotrypsin↗
PubMed1982

Tumor-associated antigens produced by mouse mammary tumor cells in artificial capillary culture.

Mouse mammary tumor cells were cultured on a three-dimensional bundle of semipermeable hollow fibers as a prototype system for large-scale in vitro production of mammary tumor-associated antigens. Cells were seeded onto the surface of the hollow fibers that served as an artificial capillary network. The cells grew to tissue-like densities within 3 weeks, achieving the high density and three-dimensional intercellular relationships known to potentiate expression of murine mammary tumor virus (MuMTV) antigens. Significant levels of a 52,000-relative-molecular-weight (Mr) glycoprotein antigen of MuMTV (gp52) were detected on the cell side of the semipermeable membrane of the hollow fibers in a yield at least fiftyfold greater than that produced by monolayer cultures. Antigen could be collected from capillary cultures for 6-12 weeks, rather than days from monolayer cultures. Further, gp52 was collected in an undegraded state. Perfusates contained lesser amounts of cross-reactive antigenic species that were predominantly smaller than 50,000 Mr, which suggests that the fibers may be used to separate antigens from their degradation products. The production of nonviral, mammary tumor-associated antigens by cells on artificial capillaries was also demonstrated. Artificial capillary cell culture systems provide a means to obtain significant quantities of tumor-relevant antigens in a semipurified natural state.

Animals↗
PubMed1980

Detection and quantification of type C viral proteins in tissues and sera with an enzyme immunoassay.

The detection and quantification of retroviral proteins in cells, tumors, and sera by an enzyme immunoassay technique (enzyme-linked immunosorbent assay [ELISA]) is described. The ELISA technique has been applied to three viral systems: murine leukemia virus, baboon endogenous virus, and simian sarcoma virus. By detecting 0.1 nf of retroviral antigen, the sensitivity of the ELISA is comparable to that of the competition radioimmunoassay technique.

Absorption↗
PubMed1979

Human breast carcinoma antigen is immunologically related to the polypeptide of the group-specific glycoprotein of mouse mammary tumor virus.

We have shown [Mesa-Tejada, R., Keydar, I., Ramanarayanan, M., Ohno, T., Fenoglio, C. & Spiegelman, S. (1978) Proc. Natl. Acad. Sci. USA 75, 1529--1533] that an antigen immunologically related to gp52, a 52,000-dalton glycoprotein of the mouse mammary tumor virus, can be identified in sections of human breast cancer by means of an indirect immunoperoxidase technique. The specificity of the reaction was established by absorption experiments which revealed that only purified gp52, or material containing it, served to eliminate the IgG molecules responsible for the immunohistochemical reaction in the human breast tumors. We show here that the cross-reactivity between the human and murine tumor antigens is due to the polypeptide rather than the polysaccharide components of gp.52. Sugar-free gp52 prepared by deglycosylation with a mixture of glycosidases was as fully effective as the intact gp52 in removing from anti-MMTV the IgG responsible for the reaction with the human tumor antigen. In contrast, the isolated polysaccharide of gp52 was unable to exert blocking activity.

Animals↗
PubMed1979

An immunoperoxidase assay for serum ragweed-specific IgE.

A solid-phase enzyme immunoassay for allergen-specific IgE antibodies in serum is descirbed. In this technique these antibodies are allowed to bind to the allergen previously adsorbed to the wells of polystyrene microtiter plates. After a washing step the tubes are incubated with rabbit antihuman IgE labelled with horseradish peroxidase. Following a second washing step, the enzyme bound to the tubes is assayed spectrophotometrically using O-phenylene diamine as the substrate. The standard curves obtained with this method and with the RAST technique are illustrated. For the assay of serum antiragweed IgE antibodies, concordance between the results obtained with the RAST test and this immunoperoxidase assay was observed in 85 or 95 (90%) patients with symptoms of ragweed hayfever. The coefficients of variation ranged from 4.4% (2SD +/- .010) TO 14% (2SD +/- .008). The advantages of using peroxidase as the enzymatic marker for the assay of allergen-specific IgE are discussed.

Allergens↗
PubMed1978

Detection of viral proteins in mouse mammary tumors by immunoperoxidase staining of paraffin sections.

An indirect immunoperoxidase method is described, which can readily detect viral antigens in paraffin sections of primary, transplanted, and metastatic mammary tumors of mice. In addition to having the obvious advantage of not being limited to fresh specimens, immunoperoxidase staining of paraffin sections proved to be superior in many respects when compared with immunofluorescence and frozen sections. Immunoperoxidase staining of paraffin sections is permanent and provides the kind of histological detail required for precise cytological identification and localization with light microscopy. All of 25 tumors and 4 metastatic lesions showed evidence of glycoprotein gp52 as well as other mouse mammary tumor viral antigens. The pattern and intensity of the stain were related to the degree of histologic differentiation of the tumor. Wide variations in expression of viral antigens by individual malignant cells were observed within the same tumor.

Animals↗
PubMed1978

Detection in human breast carcinomas of an antigen immunologically related to a group-specific antigen of mouse mammary tumor virus.

An antigen immunologically related to a group-specific antigen (gp52, a 52,000-dalton glycoprotein) of the mouse mammary tumor virus has been identified in paraffin sections of human breast cancers by means of the indirect immunoperoxidase technique. The specificity of the reaction with antibody against mouse mammary tumor virus was examined by absorption of the IgG with the following: (a) purified gp52; (b) a number of virus preparations (mouse mammary tumor virus, Rauscher leukemia virus, simian sarcoma virus, baboon endogenous virus, and Mason-Pfizer monkey virus); (c) normal plasma, leukocytes, breast tissue, milk, actin, collagen, and hyaluronic acid, all of human origin; (d) sheep erythrocytes and mucin. Only mouse mammary tumor virus (from C(3)H or Paris RIII strains and grown in either murine or feline cells) and purified gp52 eliminated the immunohistochemical reaction in the human breast tumors. Positive reactions were seen in 51 of 131 (39%) breast carcinomas of various histologic types, a minimal estimate in view of the limited number of sections from each tumor that could be examined. Negative reactions were obtained in all 119 benign breast lesions (cystic disease, fibroadenoma, papilloma, gynecomastia) and in all 18 normal breast tissues. With one exception, 99 carcinomas from 13 organs other than breast and 8 cystosarcomas were all negative.

Adenocarcinoma↗
PubMed1978

Immunohistochemical detection of a cross-reacting virus antigen in mouse mammary tumors and human breast carcinomas.

An indirect immunoperoxidase method was first used to localize mouse mammary tumor virus (MMTV) antigens in paraffin sections of mammary tumors of Paris RIII and CD8F1 mice. By using the same method, an antigen with cross-reactivity to a group-specific antigen (gp52, a 52,000 dalton glycoprotein) of MMTV was detected in paraffin sections of human breast carcinomas. The specificity of this reaction with antibody against MMTV was examined by absorption of the IgG with: a) purified gp52; b) several relevant and irrelevant viral preparations; c) normal human plasma, leukocytes, breast tissue, milk, actin, collagen, and hyaluronic acid; d) sheep erythrocytes, bovine mucin and fetal calf serum. Only MMTV and prufied gp52 eliminated the immunohistochemical reaction in human breast tumors. Positive reactions were seen in 73 of 191 (38%) breast carcinomas of various histopathologic types, while negative reactions were obtained in all 137 normal and benign cases tested. A positive reaction of uncertain specificity was observed in foci of apocrine metaplasia. With one exception, 99 carcinomas from 13 organs other than breast and eight cystosarcomas were negative.

Adenocarcinoma↗
PubMed1976

Further studies on the isolation and properties of polyriboadenylate polymerase from Escherichia coli PR7 (RNase I-, pnp).

Polyriboadenylate polymerase was isolated from Escherichia coli PR7 (RNase I-, pnp) in good yield and high purity. The enzyme catalyzes the polymerization of ATP and ADP. These polymerizations show an initial lag which can be removed by the addition of poly(A). However, poly(A) does not function as a primer. UDP and CDP can also serve as substrates but with decreased efficiency. The polymerization of CDP is enhanced by the presence of an oligonucleotide which again does not function as a primer. Polymerization of [gamma-32P]ATP or [beta-32P]ADP result in products with no radioactivity. The product formed from [alpha-32P]ATP on hydrolysis with alkali yields labeled pAp and 2',3'-AMP; thus the enzyme synthesizes poly(A) chains de novo. During the polymerization of ATP, no burst of free ADP can be detected and the time course of phosphate release from ATP ro ADP follows very closely the kinetics of polymerization. dATP and dADP are effective inhibitors of poly(A) synthesis from either ATP or ADP. Sulfhydryl reagents inhibit only the polymerization of ATP and the inhibition is fully reversed by dithiothreitol. However, the enzyme can be protected from sulfhydryl reagents by preincubation with either ATP or ADP in the absence of Mg2+ which is required for polymerization. Studies using acrylamide gel electrophoresis indicate that the polymerization activity with either ATP or nucleoside diphosphates resides in the same protein. The enzyme catalyzes the following exchanges: 32Pi into ADP, 32Pi into ATP, and [14C] ADP into ATP in the presence of phosphate. While the enzyme catalyzes the phosphorolysis of its own product, (pAp-(Ap)nA), it fails to cleave the dephosphorylated product, (Ap(Ap)nA), or ribosomal RNA or tRNA in the presence of inorganic phosphate. The differences and similarities between poly(A) polymerase and polynucleotide phosphorylase are discussed. Based on the 32P exchange studies and other properties of poly(A) polymerase, a plausible mechanism for its action is proposed.

Chloromercuribenzoates↗
PubMed1975

Presence of polyriboadenylate sequences in pulse-labeled RNA of Escherichia coli.

Pulse-labeled RNA isolated from E. coli cells grown on limiting phosphate medium and phosphate-containing medium was analyzed by oligo(dT)-cellulose chromatography and by Millipore binding assay for polyriboadenylate-containing RNA. Whereas poly(A)-containing RNA amounted to as much as 15% of the total pulse-labeled RNA from cells grown on limiting phosphate medium, pulse-labeled RNA from cells grown on phosphate medium gave values around 1.5%. Steady-state labeled RNA from cells grown on limiting phosphate medium contained 1.2% poly(A) RNA. The addition of poly(A) sequences appears to be post-transcriptional. These results strongly favor the view that bacterial mRNAs may contain poly(A) stretches.

Adenosine↗
PubMedDate not supplied

Immunohistochemical evidence for RNA virus related components in human breast cancer.

The localization of antigenic components with cross-reactivity to a 52,000 dalton group specific glycoprotein (gp52) of the mouse mammary tumor virus (MMTV) in paraffin sections of human breast carcinomas is described using an indirect immunoperoxidase method. This method was first optimized on paraffin sections of mouse mammary tumors. The specificity of the reaction observed in the human tissues was established by absorption of the specific IgG with: a) purified gp52; b) several relevant and irrelevant viral preparations; c) normal human plasma, leukocytes, breast tissue, milk, actin, collagen, and hyaluronic acid; d) sheep erythrocytes, bovine mucin and fetal calf serum. Only MMTV and purified gp52 eliminated the immunohistochemical reaction in human breast tumors. Positive reactions were seen in 171 of 376 (45.5 percent) randomly selected breast carcinomas of various histopathologic types, while negative reactions were obtained in all 137 normal and benign cases tested. In those invasive tumors with an intraductal component, a higher percentage (63.9 percent) of positive cases was seen. A positive reaction of different specificity was observed in foci of apocrine metaplasia. With one exception, 99 carcinomas from 13 organs other than breast and eight cystosarcomas were negative.

Animals↗