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W F Vann

Publications and source records attributed to W F Vann.

At least 91 records · Page 5Linked to original sources
PubMed1982

Student self-evaluation in preclinical restorative dentistry.

In this study an instrument for assessing student self-evaluation skills was developed and refined. Using this instrument, the relationship between student self-evaluation skills and psychomotor skill performance was assessed for freshman dental students in a preclinical restorative dentistry laboratory. While previous research suggests that student self-evaluation skills are positively correlated with technical skills, the results of this study indicate that students' technical skills, as evidenced by the faculty-assigned practical grades, did not differentiate students' self-evaluation skills (p less than .05). In addition, student grades did not differentiate the students' ability to recognize errors. Using this investigative method, no relationship emerged between students' self-evaluation skills and technical skills. Finally, this self-evaluation instrument appears to be an excellent way to reveal to faculty those aspects of psychomotor skill development that need to be emphasized.

Clinical Competence↗
PubMed1981

The structure of the capsular polysaccharide (K5 antigen) of urinary-tract-infective Escherichia coli 010:K5:H4. A polymer similar to desulfo-heparin.

The capsular polysaccharide was isolated from Escherichia coli 010:K5:H4; it could not be obtained from a uncapsulated (K5-) mutant. It contains N-acetylglucosamine and glucuronic acid in a molar ratio of 1:1. Acid hydrolysis of the acidic polysaccharide as well as Smith degradation and degradation by deamination of the carboxyl-reduced polysaccharide suggested that the polysaccharide is composed of a disaccharide repeating unit. The data obtained by methylation analysis and nuclear magnetic resonance spectroscopy indicated that the repeating sequence of the capsular polysaccharide is the 4-beta-glucuronyl-1,4-alpha-N-acetylglucosaminyl unit. This structure is similar to that of desulfo-heparin.

Acetylation↗
PubMed1981

Molecular cloning of the K1 capsular polysaccharide genes of E. coli.

Epidemiological and immunological evidence indicates that the K1 capsular polysaccharide confers the property of virulence on Escherichia coli. E coli K1 is associated with invasive diseases in humans and in laboratory and domesticated animals. K1 isolates account for 80% of E. coli neonatal meningitis and comprise the majority of capsular types in neonatal septicaemia without meningitis and in childhood pyelonephritis. Passive administration of K1 antibodies prevented bacteraemia and meningitis in infant rats fed E. coli K1. Nonencapsulated derivatives of these invasive K1 strains did not cause bacteraemia in infant rats, although intestinal colonization was similar to that of the parent strains (M. Achtman and R.P.S., unpublished results). Several reports propose that the E. coli K1 capsular polysaccharide exerts an anti-phagocytic effect similar to that observed with other pathogenic encapsulated bacteria. One approach to studying whether the K1 antigen is sufficient to confer virulence of if other E. coli structures are necessary is to isolate the K1 genes for genetic and biochemical analysis. Recombinant DNA methodology provides a powerful tool for such an approach. Here, we report the molecular cloning of the E. coli K1 antigen genes. The cloned K1 genes synthesize a capsule in E. coli K12 indistinguishable chemically and immunologically from that of wild-type K1 strains.

Cloning, Molecular↗
PubMed1981

Acquisition of psychomotor skills in dentistry: an experimental teaching method.

Acquisition of psychomotor skills is one of the most important educational tasks in dental education; yet, there has been little systematic research in this area. This investigation compared a traditional method of teaching psychomotor skills with an experimental method. The investigation was conducted in a preclinical restorative dentistry laboratory course. Eighty-eight freshman students were randomly assigned to an experimental (n = 44) or control group (n = 44); instructors (n = 4) were randomly assigned to each group. The control group was taught using the traditional method used at the University of North Carolina School of Dentistry at Chapel Hill; the experimental group was taught using a guided systematic approach that relied on detailed checklists and exhaustive faculty feedback. Dependent variables measured were quality of performance on laboratory practical examinations, time required to complete practical examinations, and time required to complete the course. Results suggest that this experimental approach has promise for psychomotor skill teaching and learning in dentistry.

Education, Dental↗
PubMed1981

Comprehensive evaluation in a preclinical restorative dentistry technique course.

The student evaluation system in a preclinical technique course serves several important functions. This paper describes an evaluation system that has been used for three years. Designed to evaluate student performance in the cognitive, psychomotor, and affective domains, the system maximizes characteristics of formative evaluation and uses multiple forms of assessment to evaluate competency. Further, specific provisions have been made to ensure timely and detailed feedback and opportunities for remediation. Over the past three years, student and faculty review of this system has been positive.

Clinical Competence↗
PubMed1980

Structure of the Escherichia coli K2 capsular antigen, a teichoic acid-like polymer.

The primary structure of the K2 antigen of Escherichia coli was elucidated by composition, alkaline fragmentation, dephosphorylation with hydrofluoric acid, periodate oxidation, and methylation analysis. The polymer contains galactose in the pyranosidic and furanosidic ring form. It consists of phosphogaolactopyranosyl glycerol and phosphagalactofuranosyl glycerol units in a molar ratio of 2:1. The sequence of these units is not known. The structure of the K2 antigen is reminiscent of that of certain teichoic acids of gram-positive bacteria. Using microprecipitation, it was shown that in the polymer galactoside is immunodominant.

Antigens, Bacterial↗
PubMed1979

Structure and serological specificity of the K13-antigenic polysaccharide (K13 antigen) of urinary tract-infective Escherichia coli.

The primary structure of the K13-antigenic polysaccharide (K13 antigen) of Escherichia coli O6:K13:H1 was elucidated by composition, periodate oxidation, Smith degradation, and methylation analysis. The polysaccharide consists of a repeating sequence of 3-linked ribofuranose and 7-linked 3-deoxymannooctulosonic acid (KDO). About 50% of the KDO residues are O-acetylated at position 4 or 5. Measurement of the optical rotary dispersion indicated that in aqueous solution the K13 polysaccharide assumes a secondary structure in which the carboxyl groups of KDO are engaged. The serological specificity of the K13 polysaccharide is expressed through KDO and its O-acetyl substituent, the ribose unit being antigenically silent. There are two populations of anti-K13 antibodies one directed against the charged region of the KDO and the other against the O-acetyl groups.

Antigens, Bacterial↗
PubMed1979

Undergraduate clinical pedodontic education: an overview of two teaching systems.

This paper compares and contrasts two clinical teaching systems in undergraduate pedodontics: the block system and the total patient care system (TPC). Descriptions and rationales are given for specific block and TPC systems at two universities. Theoretical advantages and disadvantages are reviewed. Clinical data are presented that represent experiences of the graduating classes of 1978 at The University of Iowa (block) and the University of North Carolina (TPC). From this limited sample there appears to be little quantitative evidence that one system is better than the other when examining clinical experiences in the two schools studied.

Clinical Competence↗
PubMed1978

Cell-free biosynthesis of the O-acetylated N-acetylneuraminic acid capsular polysaccharide of group C meningococci.

A cell-free system was established to study the biosynthesis of group C meningococcal capsular polysaccharide, an alpha-2 leads to 9-linked N-acetylneuraminic acid (NeuAc) homopolymer containing O-acetyl groups at either C7 or C8. Sialyltransferase activity, isolated from group C meningococcus strain C-11, catalyzed incorporation of [14C]NeuAc from CMP (CMP--[14C]NeuAc) into polymeric form. This sialyltransferase was stimulated by addition of meningococcus group C and Escherichia coli K92 capsular polysaccharides, the latter being an alpha-2 leads to 8- and alpha-2 leads to 9-linked NeuAc heteropolymer. Group C meningococcal sialyltransferase did not require divalent ions but was stimulated by Mn2+. Attempts to demonstrate a lipid-soluble intermediate in the biosynthesis of this NeuAc polymer were unsuccessful. Meningococcal group C sialyltransferase incorporated NeuAc into a membrane-associated product. The polysaccharide can be extracted from the membrane-bound fraction with Triton X-100. The newly synthesized polysaccharide coprecipitates with authentic group C antigen in meningococcal group C antiserum and is degraded by sodium metaperiodate, indicating that the NeuAc polymer synthesized by the cell-free system consists of alpha-2 leads to 9 linkage. Meningococcal group C spheroplast membranes contain an O-acetylase that can catalyze the transfer of acetyl groups from acetyl coenzyme A to the in vitro-synthesized polysaccharide.

Acetylation↗
PubMed1976

Bacillus pumilus polysaccharide cross-reactive with meningococcal group A polysaccharide.

A polysaccharide, antigenically and structurally related to meningococcal group A polysaccharide, was isolated from Bacillus pumilus Sh-17. This enteric bacterium has been implicated as a source of natural meningococcal group A immunity (Myerowitz et al., 1973). The B. pumilus polysaccharide was composed of a homopolymer of (1-6)-N-acetyl-manosamine-1-phosphate, glycerol phosphate teichoic acid-containing N-acetylglucosamine and alkali-labile alanine esters, and a mucopeptide. The cross-reaction was due to the poly-(1-6)-N-acetyl-mannosamine-1-phosphate in the B. pumilus and the meningococcal group A polysaccharides, based on the following evidence. Both polysaccharides contained N-acetyl-mannosamine phosphate. Periodate oxidized the mannosamine phosphate residues of the polysaccharide and destroyed their precipitating activity with meningococcal group A antiserum. Mild acid treatment released phosphomonoesters and destroyed the meningococcal group A precipitating activity of both polysaccharides. N-acetyl-mannosamine-6-phosphate inhibited the precipitation reaction between strain Sh-17 and meningococcal group A antisera. Only mannosamine phosphate was detected in trichloroacetic acid extracts of Sh-17 polysaccharide and meningococcal group A antigen-antibody precipitates.

Amino Acids↗
PubMedDate not supplied

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↗
PubMedDate not supplied

Isolation of type 5 capsular polysaccharide from Staphylococcus aureus.

Clinical surveys have indicated the predominance of type 5 and type 8 capsular polysaccharides among clinical isolates of Staphylococcus aureus. The type 5 capsular polysaccharide was extracted from three clinical isolates of S. aureus grown on solid media, and purified by ion exchange chromatography and gel filtration. Chemical analysis showed that the type 5 capsular polysaccharide is composed of N-acetylfucosamine and N-acetylhexosaminuronic acid. Immunodiffusion and 13C nuclear magnetic resonance experiments showed that the type 5 capsular polysaccharide is both immunologically and chemically distinct from the type 8 capsular polysaccharide and the teichoic acid of S. aureus.

Bacterial Capsules↗