Addressing the fears of HIV transmission in dental practice.

Recent surveys indicate that dental personnel are prepared to provide care for HIV+/AIDS patients, but do so with some reluctance. Their specific concerns have been identified and an attempt has been made to allay these fears by examining them from scientific, clinical, epidemiologic and historical perspectives. These somewhat pragmatic criteria suggest that HIV transmission in dental practice is extremely unlikely-if not impossible. However, the explanations offered to arrive at these conclusions may fail to resolve the suspicions that some dentists and their auxiliaries harbor toward individuals demonstrating lifestyles foreign to their own. If this is so, the advice of counsellors, social scientists and behavioral modification experts must be sought if dental personnel wish to provide care to HIV+/AIDS patients in an atmosphere of mutual trust, confidence and respect.     

The effect of supragingival plaque control on the subgingival microflora

The effect of plaque control on the apical microflora of deep periodontal pockets was studied. 8 subjects exhibiting signs of chronic periodontitis were chosen for the study, each subject having at least one pocket greater than 6 mm. These subjects were placed on a plaque control programme consisting of 3 visits, during which oral hygiene instructions were given. On two visits, the teeth of these subjects were scaled and polished. Bacteriological samples from the apex of a deep pockets from each subject were collected before the commencement of the plaque control programme and again at 8 and 16 weeks after the last scale and polish. No significant difference in the microbial flora was observed before and after plaque control, but marked fluctuation in bacterial composition was noted at the 3 samplings. It was concluded that supragingival plaque reduction was not sufficient to produce significant changes in the subgingival plaque composition of deep periodontal pockets.     

Immunogenic and Antigenic Epitopes of Immunoglobulins X: Monoclonal Antibodies Specific for Human IgA, the IgA1 and IgA2 Subclasses and an nA2m(2) Iso-Allotypic Epitope

Monoclonal antibodies (McAb) specific for human IgA, the IgA1 and IgA2 subclasses and the iso-allotypic epitope nA2m(2) have been produced. Three distinct McAb recognize an IgA1-specific epitope expressed in the C alpha 2 domain or the hinge region whilst a further McAb is directed possibly to an IgA1 hinge region epitope. The McAb having nA2m(2) specificity recognizes an iso-allotypic epitope expressed within the Fab region. IgA1 and IgA2 epitopes were detected in gorilla but not rhesus or baboon sera suggesting that the IgA subclasses represent a recent gene duplication even. However, these epitopes were also detected in some non-primate sera.     

Cross-reactions between alpha-streptococci and Omniserum, a polyvalent pneumococcal serum, demonstrated by direct immunofluorescence, immunoelectroosmophoresis, and latex agglutination.

In recent years several groups have used serological methods to demonstrate pneumococcal capsular antigens in sputum. In the present study 123 strains of alpha-hemolytic streptococci (including 97 strains from sputum or pharyngeal specimens) were tested for cross-reactions with a polyvalent antipneumococcal serum (Omniserum). Representatives of the following species were included: Streptococcus bovis, S. equinus, S. intermedius, S. lactis, S. milleri, S. mitis, S. mutans, S. sobrinus, S. salivarius, S. sanguis, S. suis, and Aerococcus viridans. Serological reactions were detected by direct immunofluorescence, immunoelectroosmophoresis, and latex agglutination. Fifteen (12%) of the strains gave positive reactions by all three methods. Positive reactions were also observed with another 32 strains (26%) with two of the methods, whereas 37 strains (30%) gave positive reactions by just one technique. Altogether 84 (68%) strains gave positive reactions with one or more of the methods. Latex agglutination gave positive reactions with 26 (21%) strains compared with 57 (46%) in immunofluorescence and 63 (51%) in immunoelectroosmophoresis. Absorption of the antiserum with one alpha-hemolytic strain reduced but did not entirely eliminate the cross-reactions with five tested strains. These findings indicate a potential risk of cross-reactions with polyvalent antipneumococcal serum in tests carried out on sputa or other specimens which may be contaminated with alpha-hemolytic streptococci.     

Determination of avidity of anti-viral antibodies at 50% binding of antibody.

Binding studies with tobacco mosaic virus and specific IgG and Fab' fragments were done under conditions of 50% binding of antibody. When the log of the concentration of antigen sites required to bind 50% of the available antibody was plotted against the log of bound sites, a line was obtained which had a slope varying between 0 and 1. Instead of using the slope of this line as an index of avidity of the antiserum, it is suggested that the calculation K0 values over a range of reactant concentrations provides a better criterion for comparing the avidity of antiviral antibodies. The results of conventional binding tests were analyzed by means of Scatchard plots and were found to agree very closely with the data obtained at 50% binding of antibody.     

Electronic typewriter for the physically handicapped

An electronic typewriter suitable for use by the physically handicapped has been successfully designed and constructed. The machine is operated by placing a small magnet in a chosen hole in a character matrix, thus firing the typewriter hammers through electronic circuits. The design incorporates features to reduce user errors arising from poor spatial and temporal control by the typist.