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Biomedical subjects

S Sinha

Publications and source records attributed to S Sinha.

At least 451 records · Page 25Linked to original sources
PubMed1987

Intact microtubules are necessary for complete processing, storage and regulated secretion of von Willebrand factor by endothelial cells.

The importance of intact microtubules in the processing, storage and regulated secretion of von Willebrand factor (vWf) from Weibel-Palade bodies in endothelial cells was investigated. Human umbilical vein endothelial cells treated for 1 h with colchicine (10(-6) M) or nocodozole (10(-6) M) lost their organized microtubular network. Stimulation of these cells with secretagogues (A23187, thrombin) produced only 30% release of vWf in comparison to control cells containing intact microtubules. The nocodazole treatment was reversible. One-hour incubation in the absence of the drug was sufficient for microtubules to reform and restore the full capacity of the cells to release vWf. Long-term incubation (24 h) of endothelial cells with microtubule-destabilizing agents had a profound effect on vWf distribution. In control cells, vWf was localized to organelles in the perinuclear region (i.e., endoplasmic reticulum and Golgi apparatus) and to Weibel-Palade bodies. In drug-treated cells vWf staining was dispersed throughout the cytoplasm, and Weibel-Palade bodies were absent. The vWf synthesized in the absence of microtubules contained significantly less large multimers than that produced by control cells. Since Weibel-Palade bodies specifically contain the large multimers, we hypothesize that the structural defect in vWf secreted by cells in the absence of microtubules is due to the lack of Weibel-Palade bodies in these cultures.

Benzimidazoles↗
PubMed1987

Suppression of delayed hypersensitivity skin reactions to tuberculin by M. leprae antigens in patients with lepromatous and tuberculoid leprosy.

Delayed hypersensitivity skin reactions to tuberculin when injected alone or in mixture with antigens of M. leprae were examined in leprosy patients and in healthy controls. The tuberculin reaction was significantly inhibited in more than one half of both LL and BT patients by the soluble extract of M. leprae (leprosin), the leprosin derived 12 kD protein or leprosin depleted of the 12 kD antigen. However, suppression was not found in healthy controls from a leprosy endemic region. These results suggest that multiple M. leprae-specific antigens have an immunoregulatory function. Since suppression was demonstrable not only in LL (leprosin-anergic), but also in BT (leprosin-responder) patients it is of interest that the 'mixed' skin test can discriminate the immune status of at least certain BT patients from that of the infected but self-healing healthy controls. Corollary lymphocyte cultures failed to show any suppression by leprosing of the lymphoproliferative responses to tuberculin.

Antigens, Bacterial↗
PubMed1986

Cloning and sequencing of cDNA of bovine N-acetylglucosamine (beta 1-4)galactosyltransferase.

Galactosyltransferases constitute a family of enzymes, each member of which transfers galactose from UDPgalactose to a specific acceptor molecule, generating a specific galactose-acceptor linkage. Two synthetic oligonucleotides, 27mer and 21mer, were synthesized, based on the amino acid sequences of two peptides derived from bovine milk N-acetylglucosaminide (beta 1-4)galactosyltransferase (EC 2.4.1.90), and used as hybridization probes to isolate cDNA clones for galactosyltransferase from a bovine mammary gland cDNA library. One of the plasmids, designated pLbGT-1, contains an insert of about 3.7 kilobases that hybridizes to both of the probes and encodes the amino acid sequences of five peptides obtained from bovine milk (beta 1-4)galactosyltransferase. A second plasmid, designated pLbGT-2, contains an insert of about 4.1 kilobases that hybridizes to only the 27mer and that encodes a polypeptide containing the sequence of the carboxyl-terminal 120 residues identical to the peptide encoded by pLbGT-1; the rest of the protein sequence, however, does not contain known sequences from bovine galactosyltransferase. The two cDNAs contain a 3'-untranslated region of about 2.7 kilobases that includes two copies of the Alu-equivalent sequences. pLbGT-1 and pLbGT-2 hybridize to mRNAs of various sizes obtained from the bovine and rat mammary gland and the human mammary tumor cell line MCF-7, with the longest mRNA from each species being around 4.5 kilobases. The results show that pLbGT-1 is a cDNA clone for bovine (beta 1-4)galactosyltransferase, and pLbGT-2 encodes a protein that is structurally and may be functionally related to transferases.

Amino Acid Sequence↗
PubMed1986

Detection of mycobacterial antigens in leprosy serum immune complex.

The antigens from immune complexes of sera from patients with mycobacterial diseases were released by sodium dodecyl sulfate. The antigenic activity of the released proteins was tested by agar gel diffusion and immunoelectrophoresis. This simple method provided direct evidence for the presence of mycobacterial antigens in the immune complexes of sera from patients with leprosy and tuberculosis.

Antigen-Antibody Complex↗
PubMed1986

gamma-Glutamyltranspeptidase and the ras-induced transformation of a rat liver cell line.

The effects of activated ras genes on a continuously dividing, nontransformed, rat liver-derived epithelial cell line have been studied. Genes have been introduced into cells in conjunction with a selectable drug (G418) resistance marker. Controls were obtained by transfecting with the drug resistance gene alone. Transformed, drug-resistance colonies were obtained on transfecting with ras plus resistance marker genes. They had an altered morphology, a tendency to pile up in culture, and showed anchorage-independent growth. They also were tumorigenic in nude mice with a short latent period. None of these properties was exhibited by nontransformed, drug-resistant colonies. Transformed clones were positive on histochemical staining for the enzyme gamma-glutamyltranspeptidase. A heterogeneity of gamma-glutamyltranspeptidase activity between cells of the same transformed clone was revealed by both histochemical and cytofluorographic assays. Nontransformed clones failed to stain histochemically for the enzyme. The fluorimetric determination of the specific activity of the enzyme showed consistently higher levels in transformed cells as compared to nontransformed, drug-resistant controls. The possible relationship between cell transformation and elevated levels of gamma-glutamyltranspeptidase is discussed.

Animals↗
PubMed1986

Construction of genomic libraries of mycobacterial origin: identification of recombinants encoding mycobacterial-specific proteins.

A complete genomic library from Mycobacterium vaccae (2785 recombinants) and a partial genomic library of M. leprae and BCG (300 and 1750 clones, respectively) were constructed in the plasmid pBR322. Bam HI was selected as the restriction endonuclease for obtaining DNA cleavage products. Evidence was obtained for limited expression of the cloned mycobacterial DNA inserts in Escherichia coli. A recombinant has been identified which codes for antigen immunoreactive with rabbit anti-M. leprae antibody but not with anti-H37Rv antibody.

Antigens, Bacterial↗
PubMed1986

Immunohistological analysis of skin reaction to My1 derived from Mycobacterium leprae.

A study was made on the in situ characteristics of dermal infiltrates in a 24-hr skin reaction using monoclonal antibodies defining T-cell subsets, Ia-like antigens, Langerhans' cells, My1, and indirect immunofluorescence. The skin reaction was induced by the mycobacterial antigen My1 derived from Mycobacterium leprae. In all, 10 biopsies were studied. The infiltrates were composed of lymphocytes and polymorphonuclear leukocytes. The predominant lymphocytes in the infiltrates were activated T lymphocytes expressing OKT11, Leu3a, OKT8, and Ia-like antigens. The ratio of Leu3a+:OKT8+ cells was 1.2 +/- 0.50. Some of the cells in the infiltrates showed the presence of My1, as seen by the staining with MLO6 monoclonal antibody. No difference was observed in the numbers of OKT6+ epidermal Langerhans' cells in the skin of My1 reaction biopsies and those of normal individuals.

Antigens, Bacterial↗
PubMed1985

Epileptic facial metamorphopsia.

A 14-year-old patient with a right parietal arteriovenous malformation presented with seizures characterized by metamorphopsia of faces. Unlike adults with right hemisphere pathology she performed like an age matched control on a task requiring recognition of unfamiliar faces. This likely reflects maturational changes in hemispheric dominance for face recognition.

Adolescent↗
PubMed1985

Serological survey of leprosy and control subjects by a monoclonal antibody-based immunoassay.

A serological antibody competition test (SACT) using a murine anti-Mycobacterium leprae-specific monoclonal antibody (ML04) has been evaluated in 96 untreated leprosy patients and 128 control subjects. The test is based on the competitive inhibition by antibodies from human test sera of the binding of the specific 125I-ML04 murine monoclonal antibody to M. leprae soluble antigen coated microtiter plates. Along the spectrum of the disease, SACT positivity was observed in 100% of LL-BL, 87.5% of BB, and 46.7% of the TT-BT groups of patients. Moreover, 46.4% of apparently healthy household family contacts of multibacillary leprosy cases were also antibody positive. Sera from 15 contacts of paucibacillary leprosy cases as well as from 85 various nonleprosy subjects (tuberculosis, autoimmune disease, cancer, and healthy) were all found to be negative. These results satisfy the requirements of a leprosy-specific serodiagnostic test. The striking increase of antibody titer in all of the LL/BL patients indicates a potential prognostic utility of this test for the lepromatous shift of the disease. The observed positivity in a fraction of healthy leprosy contacts still requires prospective evaluation of disease incidence in a larger test sample.

Antibodies, Bacterial↗