Biomedical subjects
Publications and source records attributed to E H De Boever.
pAM373 is a conjugative plasmid in Enterococcus faecalis that confers a mating response to the peptide sex pheromone cAM373 which is produced also by Staphylococcus aureus and Streptococcus gordonii. Unlike other sex pheromone-inducible plasmids, pAM373 does not confer an entry exclusion phenotype.
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pAM373 is a 36.7 kb conjugative plasmid in Enterococcus faecalis that encodes a response to a peptide sex pheromone, cAM373, secreted by plasmid-free (recipient) strains of enterococci. It was identified over 15 years ago as one of five plasmids in E. faecalis strain RC73 and was of interest because a related pheromone activity could be detected in culture supernatants of Staphylococcus aureus and Streptococcus gordonii. Because of increased clinical concern relating to the possibility of mobilizing vancomycin resistance determinants from enterococci, where they are becoming common, into pathogens such as S. aureus, efforts were initiated to characterize pAM373 further. The results of a complete nucleotide sequence determination of pAM373, as well as a genetic analysis of key genes related to regulation of the pheromone response, are reported here. With regard to determinants related to conjugation, the plasmid has a structural organization similar to other known pheromone-responsive plasmids such as pAD1, pCF10 and pPD1; however, there are several unique features. Although there are significant homologues relating to a pheromone-binding surface protein (TraC) and a negatively regulating protein (TraA), there is an absence of a determinant equivalent to traB of pAD1 (reduces endogenous pheromone) and a determinant for surface-exclusion protein. The precursor structure of the inhibitor peptide iAM373 was identified, and its determinant (iam373) was found to be about 500 nt upstream of an apparent transcription terminator t1. Tn917-lac insertion analyses provided interesting insights into aspects of control of the pheromone response and showed that, although the traA product is sensitive to pheromone, it appears to act differently from the traA homologue of pAD1.
Patients suffering form pain and dysfunction in the temporomandibular region sometimes ignore appointments after the initial examination. This from of noncompliance is well known and is often studied in patients suffering from recurrent headaches, arthritis, and lower back pain. Information on patients with temporomandibular disorders (TMD) who fail to attend the next visits and do not comply with the proposed treatment is scare. To 61 patients (aged 20 to 40 years) who did not attend the next visit after an initial examination and after discussing the treatment protocol, a questionnaire was mailed 6 months to 1 year after the first visit. The questions related to reasons for not attending and the possible treatment received. Some questions were also related to the present TMD state. The clinical profiles of the nonattenders were compared to those of a group of 400 TMD patients who did finish the proposed treatment (positive control). The nonattenders had more pain and dysfunction at initial examination than did the treated patients. The treated patients reported a shorter duration of symptoms before seeking treatment than did the nonattenders suggesting that the latter group had a more chronic pain state. The main reason for not returning was that symptoms improved enough or disappeared completely and spontaneously without the proposed treatment. Sixteen patients did not return for further treatment for reasons linked to the dentist-patient relationship. Fifty-seven percent of the nonattenders reported to be symptom free or sufficiently improved. One year after the initial examination and without the proposed treatment, most still had some symptoms such as clicking (59%) and reduced mouth opening (21%), but only 24% reported to be in need of treatment.
Research suggests that the tongue plays an important role in the production of oral malodor. To investigate the role of tongue surface characteristics and oral bacteria in halitosis development, the authors tested associations between odor measurements, volatile sulfur compound levels, periodontal parameters, tongue surface characteristics, presence of trypsinlike activity of organisms on the tongue and teeth and bacteriological parameters in 16 participants with complaints of oral malodor. The data indicate that the proteolytic, anaerobic flora residing on the tongue plays an essential role in the development of halitosis.
Halitosis or foetor ex ore is a frequent and complex problem with a multifactorial etiology. Nevertheless, in the majority of cases local oral conditions are the causes of the bad breath and therefore an extensive oral examination is the first step towards the identification of the source of malodor. A correct diagnosis will depend on analysis of data gathered from the patient's halitosis history, oral examination and additional laboratory and diagnostic tests.
The aim of this study was to obtain measurements of oral malodor, as measured by volatile sulfur compounds (VSC), in periodontally healthy individuals without any complaints of bad breath, and to compare the results with data obtained from patients with complaints of oral malodor. The quality of the mouth air was assessed organoleptically and a portable sulfide monitor was used to measure the concentration of VSC in mouth air. The gingival health of 35 individuals (21 M, 14 F; ages 18-57 years) without any malodor complaints was evaluated according to the Papillary Bleeding Score (PBS). Pocket depths and Bleeding upon Probing (BOP) were also recorded in 20 patients (11 females and 9 males ranging in age from 14 to 71 years) who complained of oral malodor. Scrapings of the dorsal surface of the tongue and each of 6 plaque samples per patient were evaluated for the presence of BANA-positive species, such as T. denticola, P. gingivalis, and B. forsythus. The organoleptic ratings and VSC values were significantly higher in the complaint group (p < 0.05). Subjects in the complaint group had a significantly higher percentage of bleeding sites (p < 0.005) and had significantly more plaques that tested positive for the presence of BANA-hydrolyzing species (p < 0.05). Tongue scrapings of subjects with a high organoleptic score consistently yielded a positive BANA reaction suggesting that the dorsal surface of the tongue is an important niche for BANA-positive, VSC-producing bacteria. This study suggests that the primary sources of VSC production are BANA-hydrolyzing bacteria in the plaque and on the dorsal surface of the tongue.