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W F Vann

Publications and source records attributed to W F Vann.

At least 55 records · Page 3Linked to original sources
PubMed1988

Structural studies of the Escherichia coli K93 and K53 capsular polysaccharides.

The structures of the Escherichia coli K93 and K53 capsular polysaccharides have been investigated by chemical and spectroscopic methods. The repeating unit of both polymers was found to be----3)-beta-D-Galf-(1----f)-beta-D-GlcAp-(1. The O-5 and O-6 atoms of D-galactose are acetylated in the repeating unit of the K93 polymer, but only O-2 is acetylated in the K53 polymer. The K93 polysaccharide is cross-reactive with the Neisseria meningitidis Group A capsular polysaccharide (of known structure). The K53 polysaccharide, although structurally similar to that from K93 organisms, does not cross-react with the Group A polymer.

Carbohydrate Conformation↗
PubMed1988

Capsular antibodies induce type-specific phagocytosis of capsulated Staphylococcus aureus by human polymorphonuclear leukocytes.

Capsular types 5 and 8, which account for about 70% of Staphylococcus aureus strains isolated from the blood of patients, resisted in vitro phagocytosis by human polymorphonuclear leukocytes (PMN). Antisera and monoclonal antibody to type 5 and 8 capsular polysaccharides (CPS) induced type-specific in vitro phagocytosis of capsulated organisms by PMN. Antibodies directed against the O-acetyl moiety of the type 8 CPS were more effective in inducing phagocytosis of type 8 organisms by PMN. Either type-specific antiserum or monoclonal antibody reactive with the native O-acetylated type 8 CPS was most effective in inducing in vitro phagocytosis of type 8 organisms by PMN. These results provide further evidence that CPS of S. aureus are associated with host immunity to this organism.

Antibodies, Bacterial↗
PubMed1988

Synthesis and physicochemical and immunological characterization of pneumococcus type 12F polysaccharide-diphtheria toxoid conjugates.

A scheme for the synthesis and purification of conjugates, composed of the type 12F capsular polysaccharide of Streptococcus pneumoniae (Pn12F) and diphtheria toxoid, is described. The scheme is a modification of that described previously for the Vi capsular polysaccharide of Salmonella typhi, a linear homopolymer of N-acetylgalactoseaminouronic acid (S. C. Szu, A. L. Stone, J. D. Robbins, R. Schneerson, and J. B. Robbins, J. Exp. Med. 166:1510-1524, 1986). Pn12F is a branched-chain copolymer composed of a hexasaccharide repeating unit containing an aminouronic acid, N-acetylmannoseaminouronic acid (K. Leontein, B. Lindberg, and J. Lonngren, Can. J. Chem. 59:2081-2085, 1981). Sulfhydryl groups were introduced into Pn12F by forming an amide bond between cystamine and carboxyl groups of N-acetylmannoseaminouronic acid in the presence of a carbodiimide. The disulfide moiety of cystamine was reduced to form the cysteamine derivative of Pn12F which was, in turn, covalently bound to diphtheria toxoid by using the heterobifunctional linker N-succinimidyl-3-(2-pyridylthio)propionate. Unbound, high-molecular-weight Pn12F was removed from the conjugate by hydrophobic interaction chromatography through octyl Sepharose by using n-octyl-beta-D-glucopyranoside as the eluent. In young outbred mice, Pn12F did not elicit detectable serum antibodies. Pn12F-diphtheria toxoid, in contrast, elicited antibodies after two injections and had T-cell-dependent properties as evidenced by a response to priming and by its ability to elicit booster responses. This scheme seems applicable to the synthesis of conjugates with other capsular polysaccharides containing aminouronic acids. Clinical evaluation of Pn12F-diphtheria toxoid conjugates in healthy and in immunocompromised hosts is planned.

Animals↗
PubMed1988

Wear of composite resin restorations in primary versus permanent molar teeth.

The purpose of this investigation was to compare the wear rates of posterior composite resin restorations in primary versus permanent teeth. Based on theories of composite wear in primary molars, as well as on empirical observations, we hypothesized that wear would be greater in permanent tooth restorations. In Part I of the study, quantitative wear data from four different clinical trials (three permanent tooth studies and one primary tooth study) were compared. The same posterior composite restorative material was investigated in each of the four studies. In Part II of the study, quantitative wear data were drawn from a single clinical trial wherein the same experimental posterior composite material was placed in primary and permanent molars in the same children. In Part II, the baseline sample size included posterior composite restorations placed in 92 primary and 95 permanent molars in all children (ages 7-10). Quantitative wear data were obtained by the cast assessment method at baseline, six, 12, and 24 months. The 24-month sample size was based on 48 available primary molar restorations and 89 permanent molar restorations. The loss of primary restorations was due almost exclusively to natural exfoliations. Findings in Part I revealed no significant difference in the wear of primary versus permanent molar restorations. In Part II, wear findings for primary molar versus permanent teeth, respectively, were as follows (in micrometers): 47 versus 49 at six months; 86 versus 80 at 12 months; and 133 versus 131 at 24 months. With a Wilcoxon two-sample test and an alpha level of 0.05, there were no significant differences at any recall for the wear rate of primary versus permanent restorations. These results differ sharply from findings reported by others.

Child↗
PubMed1988

Assessing composite resin wear in primary molars: four-year findings.

Many investigators have reported minimal wear of resin restorations in primary molars. Until recently, quantitative wear assessments have not been reported. The purpose of this investigation was (1) to present and contrast data from two 48-month clinical trials wherein quantitative wear assessments were used to evaluate wear of resin restorations in primary molars, and (2) to compare these results with those using the USPHS method of wear assessment. The data were collected from two different clinical trials. One was conducted at the University of California in San Francisco by Tonn and Ryge (TR Trial). The other was conducted at the University of North Carolina at Chapel Hill by Oldenburg, Vann, and Dilley (OVD Trial). The OVD Trial had a sample size of 45 patients with 106 restorations; the TR Trial had 44 patients with 96 restorations. The restorations in both trials were Class I and II restorations in occlusion. They were placed with the experimental light-cured posterior composite resin F-70, later marketed as Ful-Fill. At baseline, six, 12, 24, 36, and 48 months, restorations were evaluated by two evaluators trained in USPHS criteria as well as by a quantitative method of wear assessment, the standard cast technique as described by Leinfelder. Interstudy comparisons were made by Chi-square tests (USPHS evaluations) and ANOVA (quantitative assessments). The results showed that resin restorations in primary molars exhibited progressive wear with time in service. The rate and quantity of wear were very similar to those seen in permanent posterior teeth over 36 months. Findings agree with previous reports that the USPHS evaluation criteria are insensitive in detecting early wear in primary molars.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1987

Purification, properties, and genetic location of Escherichia coli cytidine 5'-monophosphate N-acetylneuraminic acid synthetase.

N-Acetylneuraminic acid cytidylyltransferase (EC 2.7.7.43) (CMP-NeuAc synthetase) catalyzes the formation of cytidine monophosphate N-acetylneuraminic acid. We have purified CMP-NeuAc synthetase from an Escherichia coli O18:K1 cytoplasmic fraction to apparent homogeneity by ion exchange chromatography and affinity chromatography on CDP-ethanolamine linked to agarose. The enzyme has a specific activity of 2.1 mumol/mg/min and migrates as a single protein and activity band on nondenaturing polyacrylamide gel electrophoresis. The enzyme has a requirement for Mg2+ or Mn2+ and exhibits optimal activity between pH 9.0 and 10. The apparent Michaelis constants for the CTP and NeuAc are 0.31 and 4 mM, respectively. The CTP analogues 5-mercuri-CTP and CTP-2',3'-dialdehyde are inhibitors. The purified CMP-N-acetylneuraminic acid synthetase has a molecular weight of approximately 50,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The gene encoding CMP-N-acetylneuraminic acid synthetase is located on a 3.3-kilobase HindIII fragment. The purified enzyme appears to be identical to the 50,000 Mr polypeptide encoded by this gene based on insertion mutations that result in the loss of detectable enzymatic activity. The amino-terminal sequence of the purified protein was used to locate the start codon for the CMP-NeuAc synthetase gene. Both the enzyme and the 50,000 Mr polypeptide have the same NH2-terminal amino acid sequence. Antibodies prepared to a peptide derived from the NH2-terminal amino acid sequence bind to purified CMP-NeuAc synthetase.

Amino Acid Sequence↗
PubMed1987

Translocation of capsular polysaccharides in pathogenic strains of Escherichia coli requires a 60-kilodalton periplasmic protein.

An 11.6-kilobase (kb) region of a 34-kb fragment of Escherichia coli DNA that encodes the K1 capsular polysaccharide genes is necessary for translocation of the K1 polysaccharide to the bacterial cell surface. This 11.6-kb region contains a gene, kpsD, encoding a 60-kilodalton protein. The kpsD gene was localized to a 2.4-kb PstI-BamHI fragment. Cells harboring a Tn1000 insertion in kpsD did not synthesize the 60-kilodalton protein and did not express polysaccharide on the cell surface. Immunodiffusion and rocket immunoelectrophoresis of cell extracts, however, demonstrated that K1 polysaccharide was synthesized by these cells. We present evidence that the kpsD gene product is synthesized as a precursor and that the processed form is located in the periplasmic space. Analysis of alkaline phosphatase activity of a kpsD-phoA fusion demonstrated that kpsD expression was under positive regulation. A 260-base-pair AluI fragment located within the kpsD coding sequence was used as a probe and was found to hybridize to chromosomal DNA from E. coli that synthesizes the K2, K5, K7, K12, and K13 capsular polysaccharides but not K3 and K100. These results suggest that the kpsD gene product may be required for export not only of K1 but for other K antigens as well.

Alkaline Phosphatase↗
PubMed1986

3'-O-(4-benzoyl)benzoylcytidine 5'-triphosphate. A substrate and photoaffinity label for CMP-N-acetylneuraminic acid synthetase.

A photoreactive, radiolabeled pyrimidine nucleotide, 3'-O-(4-benzoyl)benzoylcytidine 5'-triphosphate was synthesized from benzoylbenzoic acid and radiolabeled CTP. Benzoylbenzoyl-[5-3H]CTP could substitute for CTP, in an enzymatic reaction with N-acetylneuraminic acid catalyzed by Escherichia coli or rat liver CMP-NeuAc synthetase, to yield radiolabeled benzoyl-benzoyl-CMP-NeuAc. E. coli CMP-NeuAc synthetase could be specifically radiolabeled using benzoylbenzoyl-[alpha-32P]CTP as a photoaffinity label. This specific covalent binding occurred using enzyme preparations of different degrees of purity. These results suggest that benzoylbenzoic acid derivatives of pyrimidines should be of general use in the identification and active site mapping of pyrimidine-requiring proteins and enzymes. These include glycosyltransferases, sugar nucleotide synthetases, and transporters, and enzymes participating in the conjugation of bile acids and biosynthesis of nucleic acids and choline nucleotides.

Affinity Labels↗
PubMed1985

An avidin-biotin based ELISA for quantitation of antibody to bacterial polysaccharides.

A solid phase immunoassay utilizing avidin-biotin binding has been developed for measuring anticapsular polysaccharide antibodies. Capsular polysaccharides of Escherichia coli K1, Haemophilus influenzae type b, Staphylococcus aureus types 5 and 8, and levan from Aerobacter levanicum have been biotinylated through -OH or COOH groups with retention of antigenicity. Polysaccharides were immobilized on avidin-coated microtiter wells for use in an enzyme-linked immunosorbent assay (ELISA) to detect antibody. Two preparations of biotinylated S. aureus type 8 polysaccharide were equivalent as antigens in ELISA. Specificity was demonstrated by absorption of antisera, by competitive inhibition with purified antigens, and by reaction with specific monoclonal or myeloma antibodies. Reproducibility of the assay for H. influenzae type b and S. aureus type 8 antibody was demonstrated by replicate titrations of high and low level antisera.

Antibodies, Bacterial↗
PubMed1985

Studies on immunity against Escherichia coli K13 with monoclonal anti-K13 and anti-anti-K13.

The structural basis for the cross-reactivity between the Escherichia coli K13, K20 and K23 capsular polysaccharides is the----)-beta-ribofuranosyl-(1----7)-beta-2-keto-3-deoxyoctonate polymer. Monoclonal antibodies against E. coli K13 which require O-acetyl-2-keto-3-deoxyoctonate for binding were further investigated. Such antibodies, of both the IgG and the IgM isotype, opsonized E. coli K13 in vitro and protected against intraperitoneal infection in mice as well as ascending pyelonephritis in rats. A monoclonal IgG1 anti-idiotype, specific for the K13 polysaccharide combining site of a protective IgM idiotype, primed for protection against intraperitoneal infection with live E. coli K13 following K13 injections at four as well as 12 weeks of age, the K13 polysaccharide alone did not immunize and protect. The monoclonal anti-K13 idiotype only primed for protection at four weeks of age. These findings suggest a strong effect of a single idiotype on the outcome of a bacterial infection.

Animals↗
PubMed1985

Reactivity of type-specific monoclonal antibodies with Staphylococcus aureus clinical isolates and purified capsular polysaccharide.

Staphylococcus aureus has been classified into at least eight different capsular types by using polyclonal rabbit antisera specific for their associated capsular polysaccharides. We produced and characterized monoclonal antibodies reactive with two serologically distinct capsular types, types 5 and 8, which account for more than 70% of all S. aureus bacteremias. These type-specific, monoclonal antibodies reacted with S. aureus clinical isolates possessing the homologous capsular type and exhibited no cross-reactivity against S. aureus clinical isolates possessing the heterologous capsular type, nontypeable S. aureus clinical isolates, Staphylococcus epidermidis clinical isolates, or a variety of gram-negative organisms. The anti-type 8 monoclonal antibodies also reacted with purified capsular polysaccharide derived from the prototype type 8 S. aureus strain.

Antibodies, Bacterial↗