Penicillins for the prophylaxis of bacterial endocarditis in dentistry

BACKGROUND

Many dental procedures cause bacteraemia and it is believed that this may lead to bacterial endocarditis (BE) in a few people. Guidelines in many countries recommend that prior to invasive dental procedures antibiotics are administered to people at high risk of endocarditis. However, it is unclear whether the potential risks of this prophylaxis outweigh the potential benefits.

OBJECTIVES

To determine whether prophylactic penicillin administration compared to no such administration or placebo before invasive dental procedures in people at increased risk of BE influences mortality, serious illness or endocarditis incidence.

SEARCH STRATEGY

The search strategy was developed on MEDLINE and adapted for use on the Cochrane Oral Health, Heart and Infectious Diseases Groups' Trials Registers (to October 2003), as well as the following databases: Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2002), OLDMEDLINE (1966 to June 2002); EMBASE (1980 to June 2002); SIGLE (to June 2002); and the Meta-register of current controlled trials.

SELECTION CRITERIA

Due to the low incidence of BE it was anticipated that few if any trials would be located. For this reason, cohort and case controlled studies were included where suitably matched control or comparison groups had been studied. The intervention was the administration of penicillin compared to no such administration before a dental procedure in people with an increased risk of BE. Cohort studies would need to follow those at increased risk and assess outcomes following any invasive dental procedures, grouping by whether prophylaxis was received. Included case control studies would need to match people who had developed endocarditis (and who were known to be at increased risk before undergoing an invasive dental procedure preceding the onset of endocarditis) with those at similar risk but who had not developed endocarditis. Outcomes of interest were: mortality or serious adverse event requiring hospital admission; development of endocarditis following any dental procedure in a defined time period; development of endocarditis due to other non-dental causes; any recorded adverse events to the antibiotics; and cost implications of the antibiotic provision for the care of those patients who develop endocarditis.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected studies for inclusion, then assessed quality and extracted data from the included study.

MAIN RESULTS

No RCTs, CCTs or cohort studies were included. One case-control study met the inclusion criteria. It collected all the cases of endocarditis in the Netherlands over 2 years, finding a total of 24 people who developed endocarditis within 180 days of an invasive dental procedure, definitely requiring prophylaxis according to current guidelines and who were at increased risk of endocarditis due to a pre-existing cardiac problem. This study included participants who died because of the endocarditis (using proxys). Controls attended local cardiology outpatient clinics for similar cardiac problems, had undergone an invasive dental procedure within the past 180 days and were matched by age with the cases. No significant effect of penicillin prophylaxis on the incidence of endocarditis could be seen. No data were found on other outcomes.

REVIEWERS' CONCLUSIONS

There is no evidence about whether penicillin prophylaxis is effective or ineffective against bacterial endocarditis in people at risk who are about to undergo an invasive dental procedure. There is a lack of evidence to support published guidelines in this area. It is not clear whether the potential harms and costs of penicillin administration outweigh any beneficial effect. Ethically practitioners need to discuss the potential benefits and harms of antibiotic prophylaxis with their patients before a decision is made about administration.

Temporal variability of dissolved P speciation in a eutrophic reservoir--implications for predicating algal growth

Weak-anion exchange chromatography was used to explore the temporal variability in the speciation of dissolved P in the surface layer of a eutrophic reservoir. Authentic free ortho-P ion was the most common form of P on three of the five sampling occasions-including during a bloom of the green algae Botryococcus braunii indicating that the bloom was not P limited. Conversely, the absence of authentic ortho-P during a bloom of the dinoflagellate Ceratium hirundinella suggested the bloom was either P limited or co-limited. These observations were confirmed by algal-growth bioassay experiments.

The presence of multiple regions of homozygous deletion at the CSMD1 locus in oral squamous cell carcinoma question the role of CSMD1 in head and neck carcinogenesis

We and others previously identified a region of hemizygous or homozygous deletion at chromosome band 8p23 in oral and oropharyngeal squamous cell carcinomas (OSCCs) and many other cancer types, suggesting the presence of a tumor-suppressor gene (TSG) in this region. Recently, based on a single region of homozygous deletion in head and neck squamous cell carcinomas (HNSCC), a putative TSG, CUB and sushi multiple domains-1 (CSMD1), has been identified. In the present study, we mapped three OSCC cell lines with previously described homozygous deletions at a high resolution onto a detailed physical map. Critically, this map covered a wider region than that used in previous studies, and in contrast to these studies, our results revealed multiple regions of homozygous deletion within a small interval on 8p23. To investigate this deletion pattern further, we generated a panel of 34 sequence tagged site (STS) markers spanning the region and tested these three cell lines and an additional 34 OSCC cell lines, identifying homozygous deletions in a further four. Combining the results from all seven deleted cell lines identified three non-overlapping regions of homozygous deletion. This complex pattern could be consistent with the presence of multiple TSGs or one very large TSG in this region, and/or specific chromosomal instability. CSMD1 spans two of the three deleted regions and, therefore, would appear to be an excellent candidate for a TSG. However, deletion mapping with STSs corresponding to the exons of CSMD1 shows that some of the deletions do not interrupt its coding region, and in other cell lines the coding region is interrupted by two discontinuous homozygous deletions, suggesting the presence of redundant deletions. These results call into question whether the CSMD1 gene is the 8p23 TSG or whether this or any other genes at this locus are involved in the development of OSCC.

Antibiotics to prevent complications following dental implant treatment

BACKGROUND

Some dental implant failures may be due to bacterial contamination at implant insertion. Infections around biomaterials are difficult to treat and almost all infected implants have to be removed. In general, antibiotic prophylaxis in surgery is only indicated for patients at risk of infectious endocarditis, for patients with reduced host-response, when surgery is performed in infected sites, in cases of extensive and prolonged surgical interventions and when large foreign materials are implanted. To minimise infections after dental implant placement various prophylactic systemic antibiotic regimens have been suggested. More recent protocols recommended short term prophylaxis, if antibiotics have to be used. With the administration of antibiotics adverse events may occur, ranging from diarrhoea to life-threatening allergic reactions. Another major concern associated with the widespread use of antibiotics is the selection of antibiotic-resistant bacteria. The use of antibiotics in implant dentistry is controversial. It would be useful to know whether prophylactic antibiotics are effective in reducing failures of dental implants.

OBJECTIVES

To assess the beneficial or harmful effects of the administration of prophylactic antibiotics for dental implant placement versus no antibiotic/placebo administration and if antibiotics are of benefit, to find which type, dosage and duration is the most effective.

SEARCH STRATEGY

We searched the Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. We handsearched several dental journals. No language restrictions were applied. Personal contacts and manufacturers of dental implants were contacted to identify unpublished trials. Most recent search: March 2003.

SELECTION CRITERIA

Randomised controlled clinical trials (RCTs) with a follow up of at least 3 months comparing the administration of various prophylactic antibiotics regimens and no antibiotics/placebo to patients undergoing dental implant placement. Outcome measures were prosthesis failures, implant failures, postoperative infections and adverse events (gastrointestinal, hypersensitivity).

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were to be conducted in duplicate and independently by two reviewers. Results were to be expressed as random effects models using weighted mean differences for continuous outcomes and relative risk for dichotomous outcomes with 95% confidence interval. Heterogeneity was to be investigated including both clinical and methodological factors.

MAIN RESULTS

No RCTs were identified.

REVIEWER'S CONCLUSIONS

There is not appropriate scientific evidence to recommend or discourage the use of prophylactic systemic antibiotics to prevent complications and failures of dental implants. Even though the present review did not assess the effectiveness of prophylactic antibiotics for patients at risk for endocarditis, it seems sensible to recommend the use of prophylactic antibiotics for patients at high and moderate risk for endocarditis, with immunodeficiencies, metabolic diseases, irradiated in the head and neck area and when an extensive or prolonged surgery is anticipated.

4.3 Towards a global superstore of quality-assured modularized learning programmes

Our section's assignment entails exploration of the current challenges to develop criteria for quality assurance of dental e-learning material. Our work has involved comparison of current methods of assessment, the identification of best practice and the formulation of guidelines and criteria for producers and assessors. We anticipate the need for a standing international body responsible for the revision and refinement of guidelines and criteria and that might award a 'Seal of Approval'.

Heme oxygenase-1 induction in islet cells results in protection from apoptosis and improved in vivo function after transplantation

Transplantation of islets of Langerhans represents a viable therapeutic approach for the treatment of type 1 diabetes. Unfortunately, transplanted islets are susceptible to allogeneic recognition and rejection, recurrence of autoimmunity, and destruction by local inflammation at the site of implantation. The last of these phenomena might not only result in functional impairment and death of islet cells but could also contribute to amplifying the subsequent specific immune response. Induction of islet cell protection against inflammation could therefore be postulated to be a powerful means to improve overall graft fate. Heme oxygenase-1 (HO-1) has been described as an inducible protein capable of cytoprotection via radical scavenging and apoptosis prevention. The purpose of the present study was to analyze whether HO-1 upregulation in a beta-cell line and in freshly isolated murine islets could result in protection from apoptosis and improve in vivo functional performance. HO-1 upregulation was induced reproducibly with protoporphyrins and was correlated with protection from apoptosis induced in vitro with proinflammatory cytokines or Fas engagement. Furthermore, in vivo HO-1 upregulation resulted in improved islet function in a model of marginal mass islet transplantation in rodents. Strategies aimed at inducing HO-1 upregulation might result in improved success in islet transplantation.

Bioavailability of orally administered micronised fluticasone propionate

OBJECTIVE

The aim of this study was to determine the absolute oral bioavailability of fluticasone propionate (FP) in healthy volunteers.

METHODS

A 3-period incomplete block crossover design was used. On separate occasions, 21 male volunteers received a single 250 microg intravenous dose of FP (n = 21) and twice daily oral doses of either micronised FP 0.1 mg (n = 9), 1 mg (n = 12), 10 mg (n = 11) or placebo (n = 9) for 4 days.

RESULTS

FP was not measurable in the plasma after twice daily oral administration of a 0.1 mg dose. FP concentrations just above the limit of quantification could be measured in only 5 volunteers, and only at some time points, after administration of FP 1 mg twice daily. At a dose of 10 mg twice daily the absolute oral bioavailability of the drug was <1% when a liquid chromatography-mass spectrometry assay was used to assess plasma concentrations. Only oral doses of FP 10 mg twice daily, 10 times greater than the recommended maximum inhaled dose, produced any detectable change in urinary cortisol excretion.

CONCLUSION

The results of this study confirm that oral absorption of FP into the systemic circulation is negligible. The swallowed portion of an inhaled dose of FP is unlikely to increase the systemic exposure to the drug, thus decreasing the likelihood of adverse systemic effects.

Undergraduate orthodontic & paediatric dentistry education in Europe--the DentEd project

As a result of a European Union funded project (DentEd), a programme of visits to dental schools throughout Europe has been underway since 1998. This report describes the philosophy behind DentEd, gives a brief description of the features of a visitation, and covers the orthodontic and paediatric dentistry teaching as reported in 26 different dental schools in 16 different countries. It is based on a report submitted to DentEd from a small working group that looked at various aspects of educational provision within the two disciplines across Europe. The value of this information to teachers within the two disciplines and to the wider dental community is briefly discussed. The report recommends the adoption of an integrated course for orthodontics and paediatric dentistry. The main objectives are that the student should be able to understand orofacial and psychosocial growth and development of the child, recognize aberrant growth and development, and manage the behaviour of the child, their straightforward preventive, restorative and occlusal needs, and to make appropriate and timely referral.

Endotoxin-mediated delayed islet graft function is associated with increased intra-islet cytokine production and islet cell apoptosis

BACKGROUND

Primary nonfunction resulting in immediate graft loss is responsible for the failure of a large number of islet transplants. Evidence is accumulating to single out endotoxin contamination of the various reagents needed for islet isolation as a major cause of early graft loss.

METHODS

Islets isolated with endotoxin-containing (400 endotoxin units/ml) collagenase type V and "endotoxin-free" (3.1 endotoxin units/ml) Liberase were compared. Graft function was assessed using a syngeneic murine model of marginal islet mass transplantation. Pro-inflammatory cytokine production by islets was measured by ELISA in culture supernatants, and quantitative reverse transcriptase-PCR. Islet cell apoptosis was measured using the annexin assay.

RESULTS

Graft function was significantly delayed when islets were isolated with endotoxin-containing collagenase. Addition of endotoxin to the Liberase solution similarly delayed graft function. After 18 hr in culture, collagenase-isolated islets released higher amounts of proinflammatory cytokines compared with Liberase-isolated islets (interleukin-6: 2,185+/-1,174 pg/ml vs. 520+/-201 pg/ml; tumor necrosis factor-alpha: 304+/-298 pg/ml vs. 0; IL-1beta: 12.5 pg/ml+/-12.5 vs. 0). This observation correlated with higher cytokine mRNA expression in collagenase-isolated islets. The percentage of apoptotic islet cells immediately after isolation was 17.2%+/-9.4 in collagenase-isolated islets and 7.1%+/-2.1 in Liberase-isolated islets.

CONCLUSIONS

We propose that endotoxin contamination is the primum movens of a chain of events that involves intra-islet cytokine production and release and islet cell apoptosis, and endotoxin contamination can ultimately lead to primary nonfunction in vivo. This emphasizes the fact that using endotoxin-free reagents during isolation is a key factor for successful islet transplantation.

Identification of two highly divergent catalase genes in the fungal tomato pathogen, Cladosporium fulvum

Catalases of pathogenic micro-organisms have attracted attention as potential virulence factors. Homology-based screens were performed to identify catalase genes in the fungal tomato pathogen Cladosporium fulvum. Two highly divergent genes, Cat1 and Cat2, were isolated and characterized. Cat1 codes for a putative 566-amino-acid catalase subunit and belongs to the gene family that also encodes the mainly peroxisome-localized catalases of animal and yeast species. Cat2 codes for a putative catalase subunit of 745 amino acids and belongs to a different gene family coding for the large-subunit catalases similar to ones found in bacteria and filamentous fungi. Neither catalase had an obvious secretory signal sequence. A search for an extracellular catalase was unproductive. The Cat1 and Cat2 genes showed differential expression, with the Cat1 mRNA preferentially accumulating in spores and the Cat2 mRNA preferentially accumulating in response to external H(2)O(2). With Cat2-deleted strains, activity of the Cat2 gene product (CAT2) was identified among four proteins with catalase activity separated on non-denaturing gels. The CAT2 activity represented a minor fraction of the catalase activity in spores and H(2)O(2)-stressed mycelium, and no phenotype was observed for Cat2-deleted strains, which showed a normal response to H(2)O(2) treatment. These results indicate the existence of a complex catalase system in C. fulvum, with regard to both the structure and regulation of the genes involved. In addition, efficient C. fulvum gene-replacement technology has been established.

Temporary ovarian inactivity in elephants: relationship to status and time outside

The captive elephant population in North America is in reproductive decline and, without importation from the wild, may cease to be viable within the next several decades. The estrous cycle of three captive, reproductive-age African elephants was monitored for 3 years by measuring serum progesterone concentrations. Each elephant experienced one or more episodes of extended low progesterone (>12 weeks), analogous to supposed terminal cessation of estrous cyclicity or 'flatlining' that has been described in some captive Asian and African elephants. Other studies have reported lengthy non-luteal (follicular) phases that indicate extended episodes of ovarian inactivity; however, this phenomenon has not been examined in detail. In this study, total duration of temporary ovarian inactivity or acyclicity followed a social rank pattern, with the most subordinate female having the longest and the dominant female the shortest duration. During periods of acyclicity, the number of hours the elephants spent outside was significantly less than during non-luteal or luteal phases of the cycle. Except in one instance, behavioral data recorded by elephant keepers during their interactions with the elephants showed no change in handling during periods of ovarian inactivity. Further study is necessary to distinguish the causative agent for temporary cessation of estrous cyclicity. Understanding this phenomenon is imperative for the future reproductive viability of captive elephant populations.