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Biomedical subjects

G Wiseman

Publications and source records attributed to G Wiseman.

At least 19 recordsLinked to original sources
PubMed1991

Cellular and antibody responses directed against the HIV-1 principal neutralizing domain in HIV-1-infected children.

The principal neutralizing domain (PND) for antibody response is located within the V3 variable region of gp120 and can also stimulate T-cell responses. In some adults infected with human immunodeficiency virus (HIV) an HIV-1-specific T-cell response can be detected by demonstrating in vitro proliferation to HIV-1 proteins and peptides. In other HIV-1 infected adults an HIV-1-specific T-cell response can involve interleukin 2 (IL-2) secretion in the absence of T-cell proliferation. To elucidate the T-cell responses to PND in children, we examined the proliferative and the IL-2 secretory responses of peripheral blood lymphocytes from 19 HIV-1-infected children toward a peptide which contained a highly conserved sequence of the principal neutralizing domain of HIVMN (PND-MN). Stimulation with PND-MN induced proliferation of lymphocytes from 2 of the children and IL-2 secretion by lymphocytes from 5 of the children. In a 3-month-old infant, the in vitro cellular response to the PND-MN indicated HIV-1 infection prior to the detection p24 antigen in her serum. Although antibodies directed against PND-MN were detected in all but one of the children examined, the presence of high-affinity/avidity antibodies to the PND-MN correlated with the presence of a cellular response to PND-MN. Thus, in HIV-1-infected children an HIV-1 specific T-cell response in the absence of a proliferative response can be assessed by determination of the IL-2 secretory response and correlates with the generation of high-affinity/avidity antibodies.

Amino Acid Sequence↗
PubMed1989

Purification and characterization of the epitectin from human laryngeal carcinoma cells.

The purification and partial characterization of epitectin (previously called Ca antigen) from a human cancer cell line is described. This glycoprotein, which is expressed on a wide range of human tumors and certain specialized normal epithelia, can be detected using monoclonal antibodies, Ca1, Ca2, and Ca3. The purified glycoprotein had a high density (1.40 g/ml) on isopycnic centrifugation indicating a high carbohydrate content. The molecular mass of epitectin as determined by size-exclusion chromatography ranged from 1.0 to 1.5 x 10(6) daltons. However, the purified epitectin gave two bands of apparent molecular weight 390,000 and 350,000 on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The isoelectric points of epitectin and asialoepitectin were found to be 5.3-5.4 and 6.8, respectively. The oligosaccharides were isolated from metabolically labeled epitectin by alkaline borohydride treatment and their structures established based on high performance liquid chromatography and paper electrophoretic migration, sugar composition, the results of sequential exoglycosidase treatment, periodate oxidation, and methylation analysis. The structures of the three major fractions, which together account for about 80% of the radioactivity, were assigned as NeuNAc alpha 2----3Gal beta 1----(NeuNAc alpha 2----6)3GalNAc(OH), NeuNAc alpha 2----3Gal beta 1----3GalNAc(OH), and Gal beta 1----3 GalNAc(OH). The structures of the minor fractions were tentatively assigned as NeuNAc----Gal(NeuNAc----Gal----GlcNAc)----GalNAc(OH), Gal beta 1----(NeuNAc alpha 2----6)3GalNAc(OH), NeuNAc alpha 2----6GalNAc(OH), and GalNAc(OH). It is proposed that the protein sequence and/or the distribution of the saccharides on the protein core are the determinants on epitectin that are recognized by the Ca antibodies.

Antibodies, Monoclonal↗
PubMed1989

Steroid action on gene expression: possible roles of regulatory genes and nuclear acceptor sites.

There has been exciting progress in the understanding of the mechanism of action of steroid hormones. The structures and functions of the various receptor protein domains as well as the various domains of steroid-regulated genes, including steroid response elements, are currently being elucidated. The roles of transcription factors in the steroid-altered regulation of gene transcription are just being defined. The nature of the nuclear acceptor sites, i.e. nuclear-binding sites, for steroid receptors are under investigation. The composition, location, and function of these nuclear acceptor sites for steroid receptors is crucial for understanding the mechanism of steroid regulation of gene expression. Possible roles of specific, DNA-binding, chromatin proteins in these acceptor sites have been suggested. A very rapid action of steroids on the expression of proto-oncogenes that code for nuclear regulatory proteins has recently been described. Using this information, we have proposed a novel steroid action model utilizing "regulatory genes" whereby the steroids would rapidly alter the expression of regulatory genes (early genes) whose protein products would return to the nucleus to regulate the expression of structural genes (late genes). The latter would occur via binding of these regulatory proteins (e.g. transcription factors) to the steroid-regulatory elements neighboring these late genes. This model would explain many of the characteristics reported from many laboratories on the action of steroid hormones on gene expression.

Animals↗
PubMed1986

Electron-microscopic studies of the CA antigen, epitectin.

Epitectin, the mucin-like glycoprotein defined by the monoclonal antibodies CA1, CA2 and CA3, has been examined by electron microscopy to determine its shape and size. It appears to be a single extended strand with a mean length of about 270 nm. The antibodies CA1 and CA2 appear to bind preferentially to a terminal site on the epitectin molecule.

Antigens, Neoplasm↗
PubMed1986

Detection of the urinary 'PUM' polymorphism by the tumour-binding monoclonal antibodies Ca1, Ca2, Ca3, HMFG1, and HMFG2.

A series of human urinary mucin-like glycoproteins, previously detected using lectins to stain gels after electrophoresis, and showing genetic polymorphism (Karlsson et al., 1983) can also be detected using the tumour-binding monoclonal antibodies, Ca1, Ca2, Ca3, HMFG1, and HMFG2. The evidence from immunoprecipitation and immunoadsorbant chromatography experiments is that the epitopes recognized by these antibodies are carried on the same molecules as the lectin-binding determinants. The discovery that the antibodies bind specifically to a family of molecules which show genetic polymorphism provides a powerful new tool for the analysis of the material expressed aberrantly in cancer.

Antibodies, Monoclonal↗
PubMed1985

Ca2 and Ca3. New monoclonal antibodies evaluated as tumor markers in serous effusions.

Ca2 and Ca3 are new monoclonal antibodies of IgG1 class, directed against the Ca antigen, a mucus-type glycoprotein expressed on the surface of a wide range of malignant human cells and certain specialized normal epithelia. These antibodies were produced by immunization with purified preparations of the Ca antigen. They were tested to assess their value in the diagnosis of malignant effusions. Immuno-alkaline-phosphatase staining was used. Smears of pleural and peritoneal effusions were chosen to show: undoubted malignant cells of various types; and mesothelial cells in effusions from cases in which cancer was not in question. The Ca2 antibody, at 1 in 20 dilution of the culture supernatant, was the most specific, giving no reactions with benign mesothelial cells from any of the 35 cases tested. Malignant cells were clearly stained in 35 of 40 cases of carcinoma or mesothelioma. The staining was negative in two cases of oat cell bronchial carcinoma, and in three of four cases of carcinoma of the colon. Ca3 gave similar, but somewhat stronger, reactions with carcinoma cells, but was less specific, reacting weakly with mesothelial cells in 8 of 35 benign effusions. Because the false-negative reactions given by the Ca series of antibodies are to some extent complementary to those given by monoclonal antibodies directed against the carcinoembryonic antigen (CEA), a combination of Ca2 and anti-CEA is recommended as a most useful addition to the normal cytologic examination of effusions.

Antibodies, Monoclonal↗
PubMed1983

Structure and function of the Ca antigen.

The Ca antigen, which can be detected in a wide range of malignant human tumours by means of the Cal antibody, is a glycoprotein of the mucin type. At least 95% of the carbohydrate is 0-glycosidically linked to the polypeptide which contains high proportions of glycine, serine and glutamic acid. The carbohydrate has a very simple structure: it is composed almost entirely of tetra- tri- and disaccharides having the general formula (NeuNac)n leads to [Gal leads to GalNac] alpha leads to, where n = 0, 1 or 2. In many malignant cell lines, the antigen is produced constitutively in vitro; but in one that has been examined, its synthesis can be induced by high concentrations of lactate. Evidence is presented for the view that a primary function of this glycoprotein is to shield the cells that produce it from hydrogen ion concentrations outside of the physiological range. The presence of the Ca antigen in malignant tumours may thus be a reflection of metabolic conditions that are known to be characteristics of such tumours.

Amino Acids↗
PubMed1983

Sites of dipeptide hydrolysis in relation to sites of histidine and glucose active transport in hamster intestine.

The effects of dipeptides and amino acids on the active transport of L-histidine and D-glucose by sacs of everted small intestine of the hamster have been used to determine the sites of final hydrolysis of the dipeptides in relation to the sites of active transport of L-histidine and D-glucose. The results, plus earlier observations (Wiseman, 1977), show that (a) dipeptide active transport occurs at a superficial site, followed by progressively deeper sites for (b) final hydrolysis of glycyl-phenylalanine and phenylalanyl-glycine, then deeper (c) L-histidine active transport, then (d) final hydrolysis of alanyl-alanine, alanyl-leucine, glycyl-alanine, glycyl-proline, leucyl-alanine and leucyl-leucine, then (e) D-glucose active transport, then (f) final hydrolysis of alanyl-glycine, alanyl-valine, glycyl-glycine, prolyl-glycine, valyl-alanine and valyl-valine. The site of D-glucose active transport (2e) and all the sites superficial to it (2a-d) lie in the intestinal epithelial cell's brush-border. The location within the cell of site(s) 2f is not known; it may lie in the cytosol. All the dipeptides appeared to inhibit L-histidine active transport by the release of free amino acid and not by action of intact dipeptide, supporting the view that dipeptides and free amino acids do not share a common transport pathway in the epithelium of the small intestine.

Animals↗
PubMed1977

Site of intestinal dipeptide hydrolysis.

1. Sacs of everted small intestine of the hamster have been used to study the site of final hydrolysis of twelve dipeptides. 2. The results suggest that L-alanyl-glycine, glycyl-glycine, L-valyl-L-valine, L-alanyl-L-valine, L-valyl-L-alanine and L-prolyl-glycine are hydrolysed beyond the locus of the active transport mechanism for D-glucose, perhaps even within the cell. These may be designated class 1 (deep) dipeptides. 3. In contrast, superficial (perhaps even surface) hydrolysis seems to occur with L-alanyl-L-alanine, L-leucly-L-leucine, glycyl-L-alanine, L-alanyl-L-leucine, L-leucyl-L-alanine and glycyl-L-proline. These may be designated class 2 (superficial) dipeptides. 4. All the dipeptides were able to partially inhibit D-glucose active transport, the findings supporting the view that more than one mechanism may exist for the active absorption of the sugar.

Animals↗
PubMed1969

The use of dietary-restricted rat intestine for active transport studies.

1. The effect of dietary restriction (sufficient to produce a loss of about 32% of initial body weight) on intestinal active transport has been studied in the rat by the use of sacs of everted mid-small intestine. Eight D-sugars, four L-sugars and two D-amino acids were employed.2. Dietary restriction enhanced the normally occurring active transport of D-galactose, 3-O-methyl-D-glucose and D-methionine. In addition, sacs of dietary-restricted small intestine were able to concentrate in the serosal fluid D-fucose, D-xylose and D-histidine, which sacs of normal rat intestine could not do. The final (1 hr) serosal/mucosal concentration ratios produced for these actively transported substances were independent of net water movement.3. Sugars which were not concentrated in the serosal fluid of sacs of fully fed or dietary-restricted intestine were D-arabinose, D-fructose, D-glucosamine, D-mannose, L-arabinose, L-fucose, L-sorbose and L-xylose.4. The characteristics of D-fucose and D-xylose active transport suggest that they are transported by the mechanism which actively transports D-glucose. The comparatively low content of D-glucose in dietary-restricted intestine, compared with fully fed intestine, may be part of the explanation for observable active transport of D-fucose and D-xylose by dietary-restricted sacs.5. Thinning of the intestinal wall is believed not to be the cause of the enhanced active transport found during dietary restriction.6. The results show that dietary-restricted rat small intestine may, at times, be more useful than fully fed rat small intestine in the study of intestinal active transport.

Animals↗