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A Weintraub

Publications and source records attributed to A Weintraub.

At least 73 records · Page 4Linked to original sources
PubMed1996

Interactions of phage P22 tails with their cellular receptor, Salmonella O-antigen polysaccharide.

Bacteriophage P22 binds to its cell surface receptor, the repetitive O-antigen structure in Salmonella lipopolysaccharide, by its six homotrimeric tailspikes. Receptor binding by soluble tailspikes and the receptor-inactivating endorhamnosidase activity of the tailspike protein were studied using octa- and dodecasaccharides comprising two and three O-antigen repeats of Salmonella enteritidis and Salmonella typhimurium lipopolysaccharides. Wild-type tailspike protein and three mutants (D392N, D395N, and E359Q) with defective endorhamnosidase activity were used. Oligosaccharide binding to all three subunits, measured by a tryptophan fluorescence quench or by fluorescence depolarization of a coumarin label attached to the reducing end of the dodecasaccharide, occurs independently. At 10 degrees C, the binding affinities of all four proteins to oligosaccharides from both bacterial strains are identical within experimental error, and the binding constants for octa- and dodecasaccharides are 1 x 10(6) M(-1) and 2 x 10(6) M(-1), proving that two O-antigen repeats are sufficient for lipopolysaccharide recognition by the tailspike. Equilibration with the oligosaccharides occurs rapidly, but the endorhamnosidase produces only one cleavage every 100 s at 10 degrees C or about 2 min(-1) at the bacterial growth temperature. Thus, movement of virions in the lipopolysaccharide layer before DNA injection may involve the release and rebinding of individual tailspikes rather than hydrolysis of the O-antigen.

Bacteriophage P22↗
PubMed1996

Brucella-Salmonella lipopolysaccharide chimeras are less permeable to hydrophobic probes and more sensitive to cationic peptides and EDTA than are their native Brucella sp. counterparts.

A rough (R) Brucella abortus 45/20 mutant was more sensitive to the bactericidal activity of polymyxin B and lactoferricin B than was its smooth (S) counterpart but considerably more resistant than Salmonella montevideo. The outer membrane (OM) and isolated lipopolysaccharide (LPS) of S. montevideo showed a higher affinity for these cationic peptides than did the corresponding B. abortus OM and LPS. We took advantage of the moderate sensitivity of R B. abortus to cationic peptides to construct live R B. abortus-S-LPS chimeras to test the activities of polymyxin B, lactoferricin B, and EDTA. Homogeneous and abundant peripheral distribution of the heterologous S-LPS was observed on the surface of the chimeras, and this coating had no effect on the viability or morphology of the cells. When the heterologous LPS corresponded to the less sensitive bacterium S B. abortus S19, the chimeras were more resistant to cationic peptides; in contrast, when the S-LPS was from the more sensitive bacterium S. montevideo, the chimeras were more susceptible to the action of peptides and EDTA. A direct correlation between the amount of heterologous S-LPS on the surface of chimeric Brucella cells and peptide sensitivity was observed. Whereas the damage produced by polymyxin B in S. montevideo and B. abortus-S. montevideo S-LPS chimeras was manifested mainly as OM blebbing and inner membrane rolling, lactoferricin B caused inner membrane detachment, vacuolization, and the formation of internal electron-dense granules in these cells. Native S and R B. abortus strains were permeable to the hydrophobic probe N-phenyl-1-naphthylamine (NPN). In contrast, only reduced amounts of NPN partitioned into the OMs of the S. montevideo and B. abortus-S. montevideo S-LPS chimeras. Following peptide exposure, accelerated NPN uptake similar to that observed for S. montevideo was detected for the B. abortus-S. montevideo LPS chimeras. The partition of NPN into native or EDTA-, polymyxin B-, or lactoferricin B-treated LPS micelles of S. montevideo or B. abortus mimicked the effects observed with intact cells, and this was confirmed by using micelle hybrids of B. abortus and S. montevideo LPSs. The results showed that LPS is the main cause of B. abortus' resistance to bactericidal cationic peptides, the OM-disturbing action of divalent cationic chelants, and OM permeability to hydrophobic substances. It is proposed that these three features are related to the ability of Brucella bacteria to multiply within phagocytes.

Anti-Bacterial Agents↗
PubMed1996

Cloning and sequence of a region of Vibrio cholerae O139 Bengal and its use in PCR-based detection.

We isolated and characterized a Vibrio cholerae O139 Bengal-specific DNA region by arbitrary PCR. The fragment contains open reading frames encoding two potential glycosyltransferases possibly involved in capsular polysaccharide or lipopolysaccharide biosynthesis. In order to evaluate the possibility that this region could be used for the specific detection of V. cholerae O139 Bengal, a PCR system was established. The specificity and sensitivity of the PCR were investigated by analyzing 240 strains within the family Vibrionaceae and 178 stains of other gram-negative bacteria. All V. cholerae O139 Bengal strains tested were positive, and none of the 384 control strains were amplified. The sensitivity of the assay was 10(2) CFU/ml.

Amino Acid Sequence↗
PubMed1996

Phage specific for Vibrio cholerae O139 Bengal.

From the stool of a Vibrio cholerae O139 Bengal-infected patient, a phage that specifically lysed capsulated V. cholerae O139 strains only was isolated. The phage is useful for the confirmatory diagnosis of V. cholerae O139 infection and for the differentiation of variants that lack the capsule.

Bacteriophages↗
PubMed1995

Structural elucidation of the O-antigenic polysaccharide from Escherichia coli O44:H18.

The O-antigen polysaccharide of the lipopolysaccharide from the enteroaggregative Escherichia coli O44:H18 has been investigated. Sugar and methylation analysis, 1H- and 13C-NMR spectroscopy revealed that the polysaccharide is composed of pentasaccharide repeating units. The sequence of sugar residues was determined by use of two-dimensional nuclear Overhauser effect spectroscopy and heteronuclear multiple bond correlation experiments. The structure of the repeating unit of the O-antigen from Escherichia coli O44:H18 is as follows. [formula: see text]

Carbohydrate Sequence↗
PubMed1995

Structure of the capsular polysaccharide of Vibrio cholerae O139 synonym Bengal containing D-galactose 4,6-cyclophosphate.

The capsular polysaccharide (CPS) of Vibrio cholerae O139 synonym Bengal, which is thought to carry determinants of O-specificity, was isolated by phenol/water extraction followed by delipidation of the contaminating lipopolysaccharide at pH 4.2 and gel-permeation chromatography. The CPS contained D-galactose, 3,6-dideoxy-L-xylo-hexose (colitose, Col), 2-acetamido-2-deoxy-D-glucose, 2-acetamido-2,6-dideoxy-D-glucose (N-acetyl-D-quinovosamine, D-QuiNAc), D-galacturonic acid (D-GalA), and phosphate. The CPS was studied by NMR spectroscopy, methylation analysis, and selective degradations, including partial acid hydrolysis at pH 3.1 and dephosphorylation with aqueous 48% hydrofluoric acid, which both resulted in complete cleavage of Col. It was concluded that the CPS is built up of hexasaccharide repeating units containing inter alia D-galactose 4,6-cyclophosphate and having the following structure [structure: see text] These data basically confirm the structure of the V. cholerae CPS proposed on the basis of an NMR study [L. M. Preston et al. (1995) J. Bacteriol. 177, 835-838] and specify exactly the absolute configurations of the constituent monosaccharides and the position of the cyclic phosphate.

Carbohydrate Sequence↗
PubMed1995

Structural elucidation of the O-antigen lipopolysaccharide from two strains of Plesiomonas shigelloides that share a type-specific antigen with Shigella flexneri 6, and the common group 1 antigen with Shigella flexneri spp and Shigella dysenteriae 1.

Sugar and methylation analyses of native polysaccharides together with one-dimensional 1H- and 13C-NMR spectroscopy revealed that the two polysaccharides from strains 22074 and 12254 of Plesiomonas shigelloides are identical. The structure of the polysaccharide from strain 22074 was deduced from a uronic acid degradation and by NMR spectroscopy where heteronuclear multiple bond connectivity and two-dimensional nuclear Overhauser effect spectroscopy experiments established the pentasaccharide repeating unit as-->4)-alpha-D-GalpA-(1-->3)-alpha-D-GlcpNAc-(1-->3)-alpha-L- Rhap-(1-->2)-alpha-L-Rhap-(1-->2)-alpha-L-Rhap-(1-->.

Antigens, Bacterial↗
PubMed1995

Heterogeneity of Brucella abortus lipopolysaccharides.

This work demonstrates that Brucella lipopolysaccharide (LPS) preparations are a family of related molecules which display heterogeneity not only at the level of the O polysaccharide, but also at the core oligosaccharide and the lipid A. Sodium dodecyl sulphate/polyacrylamide gel electrophoresis and Western blotting showed that LPS from Brucella strains displayed molecular weight and antigenic heterogeneity. Smooth-type LPS (S-LPS) from B. abortus demonstrated three broad high-molecular-weight bands corresponding to S-LPS, and a low-molecular-weight band corresponding to O antigen lacking rough-type LPS (R-LPS). B. abortus R-LPS displayed four bands in increasing proportions as the molecular weight diminished. Immunodetection on high-performance thin-layer chromatography (HPTLC) with monoclonal antibodies (mAb) showed that R-LPS displayed three diffuse bands. HPTLC of O polysaccharide revealed two fast migrating bands recognized by antibodies. Gel chromatography and HPTLC analysis of core oligosaccharides from R-LPS demonstrated molecular weight heterogeneity as well as heterogeneous banding pattern, with no obvious correspondence between the two profiles. Immunodetection of lipid A on HPTLC plates revealed two major and three minor bands. Reactivity with mAbs suggested that regardless of the lipid A heterogeneity the basic structure of lipid A backbone is maintained.

Brucella abortus↗
PubMed1995

Endodontic pathogens in periodontal disease augmentation.

Periapical pathology indicating endodontic infection, when present in periodontitis-affected teeth, has recently been shown to be correlated to marginal periodontal breakdown. This has been associated with patency of dentinal tubules in the tooth cervix, an area normally devoid of cementum following periodontal therapy. These studies are, however hampered by that only circumstantial evidence such as presence of periapical destruction have been applied as criteria of endodontic infection. The aim of the present investigation was to assess the effects of endodontic pathogens on marginal periodontal wound healing on root surfaces devoid of cementum but surrounded by healthy periodontal membrane. Significant differences between infected and non-infected teeth were found with respect to pathological pocket and connective tissue: The experimental defects were covered by approximately 20% more pocket epithelium in infected teeth while defects in non-infected teeth showed approximately 10% more connective tissue coverage. It was concluded, that an intra-canal infection of endodontic pathogens stimulates epithelial downgrowth along denuded dentin surfaces with marginal communication. Extrapolated to the clinical situation, endodontic infections in periodontitis-prone patients may augment periodontitis propagation.

Animals↗
PubMed1995

Endodontic pathogens: propagation of infection through patent dentinal tubules in traumatized monkey teeth.

Periapical pathology indicating endodontic infection, when present in marginal periodontitis-affected teeth, has recently been shown to be an aggravating factor in progression of marginal destruction. This has been associated with patency of dentinal tubules in the tooth cervix, an area normally devoid of cementum following periodontal therapy. These studies are, however hampered by that only circumstantial evidence such as presence of periapical destruction have been applied as criteria of endodontic infection. The purpose of the present investigation was to study to what extent a predefined selection of endodontic pathogens inoculated in the root canal can influence periodontal pathology and healing in areas of the root covered by or devoid of cementum, using root resorption as a histomorphometric marker. Exposed dentine surfaces, in the present study showed significantly larger areas of resorption in infected roots compared to non-infected roots, while cementum surfaces showed an almost identical distribution of tissue reactions regardless of root canal infection or not. It was concluded that endodontic pathogens or their products were not able to penetrate the cementum barrier. The significantly larger areas of resorption on exposed dentine surfaces in infected roots compared to non-infected roots indicated that endodontic pathogens or their products could spread through dentinal tubules to a root surface void of cementum. Extrapolated to the marginal situation this indicated that endodontic pathogens in the root canal might be able to aggravate marginal infection in areas of root devoid of cementum.

Animals↗
PubMed1994

Structural studies of the Escherichia coli O90 O-antigen polysaccharide.

The O-specific side-chain of the lipopolysaccharide from Escherichia coli O90 has been investigated using methylation analysis, partial hydrolysis, and NMR spectroscopy as the principal methods. It is concluded that the polysaccharide is composed of tetrasaccharide repeating-units having the following structure. [formula: see text] The polysaccharide contains approximately one mole of O-acetyl groups per repeating unit, located on the fucose residue.

Carbohydrate Conformation↗
PubMed1994

Structural studies of the O-antigenic polysaccharides of Escherichia coli O3 and the enteroaggregative Escherichia coli strain 17-2.

The polysaccharide part of the lipopolysaccharide isolated from an enteroaggregative Escherichia coli isolated from a young child with diarrhoea in Santiago, Chile (strain 17-2), has been investigated. Sugar and methylation analyses of native and partially degraded polysaccharide together with 1H-NMR and 13C-NMR spectroscopies revealed that the polysaccharide is composed of pentasaccharide repeating units. The structure of the repeating unit of E. coli strain 17-2 O-polysaccharide is: [formula: see text] The structure of the O-polysaccharide from E. coli O3 was shown to be identical to that of E. coli strain 17-2 by sugar and methylation analyses and by 1H-NMR and 13C-NMR spectroscopies.

Carbohydrate Sequence↗
PubMed1994

Structural studies of the O-polysaccharide from the lipopolysaccharide of Moraxella (Branhamella) catarrhalis serotype A (strain ATCC 25238).

The polysaccharide of the Moraxella (Branhamella) catarrhalis serotype A lipopolysaccharide was prepared by mild acid hydrolysis followed by gel permeation chromatography. The structure was established by methylation analysis, mass spectrometry, and NMR spectroscopy. It is concluded that the O-antigenic polysaccharide has the following structure. [formula see text] Methylation analysis of the intact lipopolysaccharide showed that the lipid A portion consisted of 6-substituted glucosamine residues. Methylation followed by methanolysis showed that two Kdo residues were present, one terminal and one 4,5-substituted residue. A terminal Kdo thus substitutes the branch-point Kdo in the 4-position.

Carbohydrate Conformation↗
PubMed1994

Cross-reactivity between the mannan of Candida species, Klebsiella K24 polysaccharide and Salmonella C1 and E O-antigens is mediated by a terminal non-reducing beta-mannosyl residue.

Rat monoclonal antibody MASC1-MR9 (MR9) binds to a mannan of Candida species and the O-antigenic polysaccharides of Salmonella bacteria of serogroups C1 (CO) and E (EO). Mannan and glycoconjugates comprising BSA and O-antigen polysaccharides, decasaccharide-BSA (CO-BSA) or trisaccharide-BSA (EO-BSA), inhibited each other's reactivity with MR9. The saccharides beta-D-Manp-(1-->6)-alpha-D-Manp-1-OMe, beta-D-Manp(1-->3)-alpha-D-Manp-1-OMe, beta-D-Manp(1-->2)-alpha-D-Manp-1-OMe (corresponds to the terminal non-reducing end of Salmonella serogroup C1 O-antigen) and beta-D-Manp(1-->4)-alpha-L-Rhap(1-->3)-alpha-D-Galp-1-O-p-++ +trifluoroacetamido aniline (corresponds to the backbone of Salmonella serogroup E O-antigen) inhibited the binding of MR9 to these antigens whereas alpha-D-Manp(1-->3)-alpha-D-Manp-1-OMe and alpha-D-Manp(1-->4)-alpha-L- Rhap-1-O-p-nitrophenyl did not. Saccharides (3-10 residues) of mammalian origin with terminal and internal Manp alpha-1-->2, Manp alpha-1-->3 and Manp alpha-1-->6 residues also failed to inhibit at any concentration. None of the saccharides with internal beta-mannosyl residue was able to inhibit the MR9 antibody. Monosaccharides D-mannose, beta-D-Manp-1-OMe and 1,5 anhydro-D-mannitol inhibited the MR9 monoclonal antibody whereas alpha-D-Manp-1-OMe, beta-D-Glcp-1-OMe, and beta-D-Galp-1-OMe did not. In addition a Klebsiella K24 capsular polysaccharide containing a beta-D-Manp(1-->4)-alpha-D- GlcA (GlcA, glucuronic acid) as a structural element possessed an inhibitory activity. MR9 therefore recognizes an epitope within beta-mannose monosaccharide residues at the terminal non-reducing ends of carbohydrate chains in mannan, and polysaccharides in Salmonella serogroups CO and EO and Klebsiella K24.

Antibodies, Monoclonal↗