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Biomedical subjects

N Sharon

Publications and source records attributed to N Sharon.

At least 145 records · Page 8Linked to original sources
PubMed1982

Long-term effectiveness of the immunotherapy of anal condyloma acuminatum.

In a seven-year period, 200 patients with persistent or recurrent anal and perianal condyloma acuminatum were treated by immunotherapy. There were 120 primary and 80 recurrent cases in the study. Autogenous vaccine was prepared for each patient and injected subcutaneously, 0.5 ml weekly, for six weeks. Excellent results were seen in 84 per cent, fair results in 11 per cent and no benefit in 5 per cent of patients. No adverse reactions or complications were encountered. Long-term follow-up (average 46 months) was possible for 86 per cent of the patients, all of whom remained disease free. Immunotherapy is the recommended method of treatment for extensive, recurrent, or persistent anal condyloma acuminatum.

Adolescent↗
PubMed1982

Representation of social work agencies: new definition, special issues, and practice model.

Social Work administrators currently must respond to very diverse audiences in representing their agencies and programs. While skills in public relations, reporting, and community relations are viewed as essential, professional social work literature provides only limited conceptualizations and practice models. The authors propose a new definition of representation in social work agencies and suggest functional areas within which organized activities can be developed. The paper also includes: 1) a discussion of how several special issues such as the perception of welfare as stigma and agency interdependency affect the implementation of representational strategies; 2) a planning model that will assist administrators in strengthening the representation of their agencies' programs.

Administrative Personnel↗
PubMed1981

Primary structure of the carbohydrate chain of soybean agglutinin. A reinvestigation by high resolution 1H NMR spectroscopy.

In an earlier report (Lis, H., and Sharon, N. (1978) J. Biol. Chem. 253, 3468-3476) it was concluded that the plant glycoprotein soybean agglutinin contains two types of N-glycosidically linked carbohydrate units, both consisting of mannose and N-acetylgucosamine, in a molar ratio of 9:2. Both were described to have the same core structure, Man alpha (1 leads to 6)[Man alpha (1 leads to 3)]Man beta (1 leads to 4)GlcNAc beta (1 leads to 4)GlcNAc, but different patterns of branching. Here we present data showing that the asparagine-linked carbohydrate moiety of soybean agglutinin is homogeneous and possesses the following structure: (formula, see text) This conclusion is based on high resolution 1H NMR spectroscopy at 500 MHz of the isolated glycopeptide, and at 360 MHz of the oligosaccharide Man9GlcNAc obtained after digestion of the crude soybean agglutinin glycopeptide by endo-beta-N-acetylglucosaminidase H. The revised structure is identical in all respects with that of the high mannose N-glycosidic units of porcine thyroglobulin, of bovine lactotransferrin, and of the glycoprotein from Chinese hamster ovary cell membranes.

Carbohydrate Conformation↗
PubMed1981

Lipid-mediated hemagglutination and its relevance to lectin-mediated agglutination.

Oleic acid and dioleoyl phosphatidic acid at low concentrations (20 and 0.5 mu g/ml, respectively) agglutinate rabbit and rat erythrocytes, while dioleoyl phosphatidylcholine is not hemagglutinating up to 0.5 mg/ml. Palmitic acid is not a hemagglutinin and dipalmitoyl phosphatidic acid is a very poor one. A polar lipid fraction obtained from calf thymocytes and a commercial preparation of gangliosides also exhibit pronounced hemagglutinating activity. Modification of the erythrocytes by either trypsin or neuraminidase causes a marked increase in agglutination only with oleic acid, whereas glutaraldehyde fixation of the cells significantly decreases agglutination with oleic acid, dioleoyl phosphatidic acid and calf thymocyte lipids. None of the lipids tested agglutinate freshly drawn human and sheep erythrocytes, but agglutination occurs following fixation of the sheep cells with glutaraldehyde. Lipid-mediated hemagglutination is strongly inhibited by fetuin and bovine submaxillary mucin (0.5 mg/ml). Defatted bovine serum albumin, also at 0.5 mg/ml, inhibits agglutination by oleic acid, whereas agglutination by other lipids is only poorly inhibited if at all. Monosaccharides at concentration up to 0.25 M do not inhibit the hemagglutinating activity of the lipids. Comparison of the hemagglutinating properties of lipids and lectins raises the possibility that the agglutinating activity of crude biological extracts which is not inhibited by mono- or oligosaccharides may be due to lipid constituents. Since agglutination by lipids is species specific, they may serve as mediators in intercellular recognition. The mechanism of lipid-mediated hemagglutination is discussed in terms of current concepts of the fusogenic activity of these compounds.

Animals↗
PubMed1981

Bacterial adherence to cell surface sugars.

Bacterial adherence to animal cell surfaces is of interest because of its relation to pathogenicity and the insight it provides into determinants of intercellular recognition. The attachment of various strains of Escherichia coli and Salmonella spp. to epithelial cells and phagocytes is inhibited by D-mannose, and the adherence of other bacteria is inhibited by sugars such as L-fucose and D-galactose, suggesting that sugar-mediated adherence is widespread. This intercellular recognition is thought to be mediated by sugar residues (e.g. D-mannose) on the surface of animal cells, to which bacteria attach by a sugar-binding substance on their surface. The nature of the receptors on the animal cells is unknown. There is evidence that E. coli produces lectin-like substances specific for D-mannose, by which it binds to the cells. The most common form of these lectin-like substances appears to be the bacterial pili, which can be reversibly dissociated into their protein subunits. The lectin can also be in the form of bacterial flagella or tightly attached to the outer membrane of the bacteria. Mannose-specific attachment may assist bacteria in colonizing and invading their hosts: methyl alpha-D-mannoside (but not methyl alpha-D-glucoside) significantly reduced infection of the urinary tract of mice by virulent strains of E. coli. Once bacteria penetrate the host their ability to binding sugars on phagocytes may impair their virulence by facilitating phagocytosis. Further studies of the sugar-mediated bacterial adherence by organisms growing in vivo and the structural identification of the host cell receptors may lead to the design of more effective adherence inhibitors that may help to prevent certain bacterial infections.

Adhesiveness↗
PubMed1981

Human B lymphocytes form rosettes after insertion of T lymphocyte membrane constituents.

Isolated plasma membranes from human thymocytes or peripheral T lymphocytes upon their reconstitution with envelope glycoproteins of Sendai virus, afforded membrane vesicles that fused efficiently with human peripheral B cells. The b cells thus obtained acquired the ability to form regular rosettes at 4 degrees C with sheep red blood cells. However, only B cells modified by fusion with thymocyte membranes formed stable rosettes at 37 degrees C, a property which distinguished thymocytes from peripheral T cells. Transfer of membrane components between human cells provides a new approach for the investigation of the sheep red blood cell receptor as well as the structure-function relationship of other lymphocyte membrane components.

Animals↗
PubMed1981

Mannose-specific adherence of Escherichia coli freshly excreted in the urine of patients with urinary tract infections, and of isolates subcultured from the infected urine.

The mannose-specific adherence to yeast cells of Escherichia coli excreted in the urine of patients with urinary tract infections was compared with that of isolates from the same urine after growth of the bacteria in broth. The results revealed that although E. coli excreted in only 2 of 24 urine specimens exhibited mannose-specific adherence, about half of the broth cultures from these specimens did so. Examination of representative specimens of E. coli excreted in urine showed that coating antibodies, mannose-containing glycoproteins, and encapsulation were not responsible for the lack of the mannose-specific adherence. Our results suggest that E. coli strains that are genetically capable of exhibiting mannose-specific adherence may, when growing in the bladder, be in a phase of growth which suppresses the phenotypic expression of this trait. Mannose-specific adherence is indicative of the presence on the bacterial surface of adhesions (lectins) that bind the organisms to mannose residues on both epithelial and phagocytic cells. We propose that whereas at the initial stages of infection the bacteria may benefit from their ability to bind to mannose residues on epithelial cells, loss of this ability at the later stages of the infection is also beneficial, since the bacteria can no longer adhere to mannose residues on phagocytes, and are thus resistant to nonimmune phagocytosis.

Cell Adhesion↗
PubMed1981

Dissociation and reassembly of Escherichia coli type 1 pili.

Escherichia coli type 1 pili, which mediate the mannose-sensitive adherence of the bacterium to eucaryotic cells, are comprised of very stable arrays of pilin protein subunits (molecular weight, approximately 17,000). Previous methods for the dissociation of pili caused their irreversible denaturation. We have found that incubation of pili in saturated guanidine hydrochloride at 37 degrees C led to their complete dissociation, as evidenced by nephelometry and electron microscopy. Gel chromatography of the dissociated pili on a Sepharose CL-6B column in the presence of saturated guanidine hydrochloride yielded a single protein peak with a molecular weight corresponding to that of pilin. Dialysis of this peak against 5 mM tris(hydroxymethyl)aminomethane hydrochloride (pH 8.0) and rechromatography in the same buffer afforded a major protein peak, probably consisting of pilin dimers. About 25% of the protein in this peak bound to a mannan-sepharose column and could be eluted with methyl alpha-D-mannoside. The pilin dimer gave a single protein band upon polyacrylamide gel electrophoresis in the presence of 0.1% sodium dodecyl sulfate (molecular weight, 16,600) or 10 M urea and penetrated completely into 7% gels in the absence of denaturants. Reassembly of the pilin dimers into pili was achieved upon dialysis against the tris(hydroxymethyl)aminomethane buffer containing 5 mM MgCl2, as observed by electron microscopy. Thus, the conditions used allow renaturation of the dissociated subunits and may aid in further studies of the structure-function relationship of pili.

Escherichia coli↗