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Biomedical subjects

B Kwiatkowski

Publications and source records attributed to B Kwiatkowski.

12 recordsLinked to original sources
PubMed1990

Increased sensitivity to MHC-nonrestricted lysis of BL6 melanoma cells by transfection with class I H-2Kb gene.

An H-2Kb- negative clone of BL6 melanoma (BL6-8) was transfected with neor, H-2Kb, or H-2IAk genes. In an 18-h cytotoxicity assay clones with high levels of H-2Kb Ag expression were found more sensitive to lysis by spleen cells of syngenic and allogeneic mice than H-2Kb low clones. NK cells were involved in the lysis of H-2Kb+ BL6 melanoma clones, with spleen cell cytotoxicity of mice increased after poly I:C stimulation or decreased after pretreatment with anti-asialo GM1 serum or NK1.1 mAb. Anti-TNF Ab were also able to reduce the cytotoxicity of normal spleen cells and completely abolished the cytotoxicity of the NK-depleted spleen cells suggesting involvement of NC cells in lysis of H-2Kb+ BL6 melanoma clones. Increase in sensitivity of H-2Kb+ BL6 cells to natural cell-mediated cytotoxicity was associated with the appearance of NK recognizable determinants as assessed by the cold target inhibition assay. All BL6 clones, irrespective of sensitivity to natural cell-mediated cytotoxicity, showed high sensitivity to lysis by LGL-derived granules. In contrast, all H-2Kb low BL6 clones were resistant and all H-2Kb highly positive clones were sensitive to lysis by TNF-alpha. When an H-2Kb highly positive clone was selected in vitro for resistance to TNF, it concomitantly showed increased resistance to cytotoxicity by spleen cells, confirming the importance of TNF in spleen cell cytotoxicity against H-2Kb+ melanoma cells. Taken together, the data indicate that class I H-2Kb but not class II H-2IAk gene product could increase the sensitivity of BL6 cells to lysis by NK and natural cytotoxic cells as well as TNF. We hypothesize that these effects could be due to pleiotropic effects of H-2Kb gene products on various biologic properties of BL6 melanoma cells some of which may be more directly involved in regulation of tumor cell sensitivity to lysis by NK and/or natural cytotoxic cells.

Age Factors↗
PubMed1986

A bacteriophage-associated glycanase cleaving beta-pyranosidic linkages of 3-deoxy-D-manno-2-octulosonic acid (KDO).

A bacteriophage growing on Escherichia coli K13, K20, and K23 strains carries a glycanase that catalyzes the hydrolytic cleavage of the beta-ketopyranosidic linkages of 3-deoxy-D-manno-2-octulosonic acid (KDO) in the respective capsular polysaccharides. The main cleavage product of the K23 polysaccharide has been identified by 1H- and 13C-n.m.r. spectroscopy as beta beta Ribfl----7 beta KDOp2----3-beta Ribfl----7KDO. Cleavage of polysaccharides containing alpha-pyranosidic, or 5-substituted beta-pyranosidic KDO is not catalyzed by the enzyme.

Carbohydrate Conformation↗
PubMed1978

On the deacetylase activity of Vi bacteriophage III particles.

1. Using the complete phage particles as an enzyme, O-acetyl (1 leads to 4)-alpha-D-galacturonan (acetylated pectic acid) as a substrate, and gas-liquid-chromatography for the determination of the acid liberated, the virus-catalysed deacetylation of the polymer was studied. The activity was found to be stable up to about 50 degrees C, and from pH 4.5 to 9, with an optimum at pH 7.8; it was not affected by EDTA, or by 1,10-phenanthroline. The initial reaction velocity (at 37 degrees C) exhibited a simple hyperbolical dependence on the substrate concentration, with Km = 10.5 mM for O-acetyl (independent of virus concentration), and Vmax = 15 nmoles/min and 10(10) plaque forming units. The reaction was, however, rapidly inhibited by a partially deacetylated product (but neither by acetate, nor by pectic acid itself). 2. Using the natural substrate, acetylated (1 leads to 4)-2 amino-2-deoxy-alpha-D-galacturonan (Vi polysaccharide, Vi antigen), and a variety of structural analogues, the following conclusions about the substrate specificity of the Vi phage III deacetylase (acetyl-alpha-1,4-galacturonan acylhydrolase) were reached: (a) acetylated galacturonan is as good a substrate as acetylated aminogalacturonan; (b) of the two substrate diastereomers, acetylated alpha-L-guluronan (also 1 ax leads to 4 ax-linked units, but with axial acetyl residues at C-3), and beta-D-mannuronan (1 eq leads to 4 eq-linkages, and axial acetyl groups at C-2), only the former was acted upon, possibly indicating a specificity for the conformation of the polymer rather than for the configuration of the single residues; (c) all acyl analogues tested, O-monofluoroacetyl, O-propionyl, and O-butyryl galacturonan, were inert, showing a high degree of specificity for O-acetyl; (d) the oligomers, acetylated tri- and digalacturonic acid, as well as methyl-alpha-D-galacturonide, were still deacetylated, although more slowly, demonstrating tolerance of the enzyme of substrate size.

Acetylesterase↗
PubMed1977

Klebsiella serotype 25 capsular polysaccharide: primary structure and depolymerization by a bacteriophage-borne glycanase.

By partial acid hydrolysis, methylation and gas-liquid chromatography-mass spectrometry of the methylated monomers (as the alditol acetates), mass spectrometry of trimethylsilylated disaccharide alditols, as well as proton magnetic resonance, the primary structure of the Klebsiella serotype 25 capsular polysaccharide was elucidated. A glycanase activity, associated with the particles of newly isolated Klebsiella bacteriophage no. 25, was shown to catalyze the hydrolysis of the glycan.

Bacteriophages↗
PubMed1975

Disruption of Vi bacteriophage III and localization of its deacetylase activity.

It has been shown that particles of Vi bacteriophage III catalyse deacetylation of O-acetyl pectic (polygalacturonic) acid, a structural analogue of Vi polysaccharide (Vi antigen). Using this substrate, and determining the acetic acid liberated by gas-liquid chromatogrphy, a method for the estimation of Vi phage deacetylase activity has been developed. Purified particles of Vi phage III were exposed to a variety of mildly dissociative reagents and conditions, and then tested for plaque-forming and for deacetylase activity. They have also been inspected under the electron microscope. Osmotic shock, and incubation in the presence of ethylenediamine tetraacetic acid (greater than or equil 0-01 M), or of L-arginine (0-25 M), were found to cause disintegration of the virions into empty head capsids, deoxyribonucleic acid, and base plates still carrying the spikes. The mixtures of viral fragments exhibited an increased deacetylase activity. Using zonal sedimentation and ion exchange chromatography, the phage fragments obtained by treatment with ethylenediaminetetraacetic acid have been fractionated and the base plates isolated. Amongst the viral components, these structures showed the highest specific deacetylase activity. They had the shape of six-pointed stars (about 9-5 nm inner, and 14-5 nm outer diam.) with a central hole or plug (approximately 3 nm), carrying six spikes, roughly cylindrical organelles of approx. 11 X 4 nm, one at each of the points. Of the polypeptides of six sizes (P.1, about 153,000 daltons; P.2, 91,000; P.3, 71,000; P.4 56,500; P.6, 22,000), detected in whole Vi phage III virions by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, only two, P.2 and P.3 were found in the base plates.

Acetates↗
PubMed1975

Effect of UV-irradiation in vitro on adenin nucleotides metabolism, Na+ and K+ concentration, osmotic properties and submicroscopic structure of pigeon red blood cells.

Effect of UV-irradiation in vitro on metabolism of adenine nucleotides: ADP, ATP and AXP, osmotic properties and submicroscopic structure of nucleated pigeon red blood cell was investigated. Irradiation carried out for 60, 120, 180, 240 and 300 minutes. Hanau S-500 lamp with efficiency 4.34-10(8) erh/sec was used. A decrease of ATP content with a stimultaneous increase of ADP and AXP contents and a rather constant level of the sum of adenine compounds was observed. UV-irradiation caused a decrease of reversal of hemolysis and osmotic resistance to hypotonic NaCl solutions. An equivalent exchange of Na+ and K+ ion and an increase of hematocrit value, following UV-irradiation was observed. Electron microscope studies demonstrated changes of ultrastructure concerning both cell nucleus and thickness and granulation of cell membrane.

Adenine Nucleotides↗