Decision-making on the use of antimicrobial prophylaxis for dental procedures: a survey of infectious disease consultants and review

There is debate concerning use of antibiotic prophylaxis before invasive dental procedures for patients at risk of acquiring distant site infection (DSI). We determined the opinions and practices of infectious disease consultants (IDCs) regarding antimicrobial prophylaxis to prevent DSIs that result from invasive dental procedures by conducting a survey of the 797 members of the Infectious Diseases Society of America Emerging Infections Network (477 members [60%] responded). Ninety percent of respondents closely follow the American Heart Association guidelines for antibiotic prophylaxis for patients with valvular heart disease who undergo invasive dental procedures. In contrast, few IDCs recommend prophylaxis for patients with lupus erythematosus, poorly controlled diabetes mellitus, dialysis catheters or shunts, cardiac pacemakers, or ventriculoperitoneal shunts. Twenty-five percent to forty percent of respondents recommended prophylaxis for prosthetic vascular grafts, orthopedic implants, or chemotherapy-induced neutropenia. We conclude that IDCs differ considerably in their assessment of the need for prophylaxis for patients who have noncardiac risk factors for DSI. These differences underscore the need for definitive studies to delineate appropriate candidates for antimicrobial prophylaxis in dental practice.     

Comparison of two direct assays for platelet-associated IgG (PAIgG) in assessement of immune and nonimmune thrombocytopenia

A number of methods have been developed to measure platelet-associated IgG (PAIgG). The antiglobulin consumption assay directly quantitates IgG on the platelet and is sensitive and specific. A fluorescent anti- IgG assay has recently been described and has the advantage of simplicity. We compared the results of these two PAIgG assays in immune and nonimmune thrombocytopenia and nonthrombocytopenic controls. The antiglobulin consumption assay was negative in 61 of 62 and the fluorescent negative in 54 of 62 assays in nonthrombocytopenic controls, and they were negative in 11 of 13 and 8 of 13 assays, respectively, in nonimmune thrombocytopenic patients. The antiglobulin consumption assay was positive in 54 of 58 and the fluorescent positive in 24 of 58 assays of patients with immune thrombocytopenia (ITP and SLE). The overall sensitivity and specificity of the antiglobulin consumption assay was 94% and 95% and of the fluorescent assay was 44% and 82%.     

Effect of trabecular orientation on mechanical resistance and ultrasound propagation in specimens of equine vertebrae

Osteoporosis involves alterations, not only in density, but also in the architectural organisation of the bone; in particular, trabecular orientation, following the skeletal load directions, lends a high degree of stiffness to the whole bone. We investigated the relationship between trabecular orientation, density, stiffness and ultrasound (US) propagation in two orthogonal directions (par. = parallel to, and ort. = orthogonal to the main orientation of the trabeculae) in cylindrical equine bone specimens (thoracic vertebrae) where a preferential orientation is present. A total of 15 cylinders were progressively decalcified with 0.2 mol/L ethylenediaminetetraacetic acid (EDTA). At different levels of decalcification, we measured the apparent density (g/cm³), bone mineral density or BMD (g/cm²), stiffness coefficient (MPa) and various US parameters. Before decalcification, stiffness values were the same in all directions. As the decalcification proceeded, the stiffness declined and, at low BMD values, it was significantly different in the two directions, being the highest in the par. one. Different behaviours of US parameters were observed in the two directions: SoS (speed of sound) was closely related to apparent density, BMD and stiffness in the par. direction (r = 0.88, 0.92 and 0.88, respectively, p < 0.0001). In the ort. direction, no significant association has been found between SoS and apparent density, BMD or stiffness. In the same experimental setup, US fast wave amplitude (FWA) was related to apparent density and BMD in the par. direction (r = 0.72 and 0.67, respectively, p < 0.0001) and in the ort. direction (r = 0.83 and R = 0.84 respectively, p < 0.0001). FWA was also correlated to stiffness in both directions (r = 0.61 par.; 0.81 ort., p < 0.0001). These results show that trabecular orientation strongly influences both mechanical properties of bone and US propagation. Furthermore, we found that US parameters can be predictors of mechanical properties of the bone independent of bone density. (E-mail: fcavani@unimore.it)     

Outcomes of a metal-on-metal total hip replacement system

Introduction

High short-term failure rates have been reported for a variety of metal-on-metal (MoM) total hip replacements (THRs) owing to adverse reactions to metal debris (ARMD). This has led to the withdrawal of certain poorly performing THRs. This study analysed the outcomes of a MoM THR system.

Methods

Between 2004 and 2010, 578 uncemented MoM THRs (511 patients, mean age: 60.0 years) were implanted at one specialist centre. The THR system used consisted of the Corail^® stem, Pinnacle^® cup, Ultamet^® liner and Articul/eze^® femoral head (all DePuy, Leeds, UK). All patients were recalled for clinical review with imaging performed as necessary.

Results

The mean follow-up duration was 5.0 years (range: 1.0–9.1 years). Overall, 39 hips (6.7%) in 38 patients (all 36mm femoral head size) underwent revision at a mean time of 3.5 years (range: 0.01–8.3 years) from the index THR with 30 revisions (77%) performed in women. The cumulative eight-year survival rate for all THRs was 88.9% (95% confidence interval [CI]: 78.5–93.4%), with no difference (p=0.053) between male (95.2%, 95% CI: 84.2–98.7%) and female patients (85.3%, 95% CI: 70.2–92.1%) at eight years. Seventeen revisions (44%) were performed for ARMD. There was no significant difference in absolute postoperative Oxford hip scores between men and women (p=0.608). The mean acetabular inclination in unrevised THRs was 44.0°. Forty-seven non-revised THRs (8.7%) had blood metal ion concentrations above recommended thresholds (seven had periprosthetic effusions).

Conclusions

Although this MoM THR system has not failed as dramatically as other similar designs, we recommend against continued use and advise regular clinical surveillance to identify ARMD early.     

THE LIMA SUCCESS STORY — WHITHER OTHER ARTERIAL GRAFTS — ARE VEIN GRAFTS OBSOLETE ?

SUMMARY The long-term benefit of myocardial revascularisation depends largely upon the continued patency of bypass grafts, but the long-term patency of vein grafts is poor. To improve the results of myocardial revascularisation, either measures to increase the patency of saphenous vein grafts or alternative conduits are required. Use of the left internal mammary artery as a graft is known to increase survival, and this has prompted wider use of other arterial grafts in the expectation that they will further enhance the long-term results of coronary artery bypass. This policy is based upon sound theory, but convincing evidence that it improves survival is lacking. Meanwhile, advances in the understanding of the pathology of vein graft occlusion have given rise to new methods of increasing vein graft patency. While these techniques are, as yet, only experimental, if translated into clinical practice, the places of arterial and venous grafts may require further assessment.     

Adhesion of committed human hematopoietic progenitors to synthetic peptides from the C-terminal heparin-binding domain of fibronectin: cooperation between the integrin alpha 4 beta 1 and the CD44 adhesion receptor

Close interaction of human hematopoietic progenitors with the bone marrow microenvironment is important for the ordered progression of human hematopoiesis. Progenitor cell adhesion to stroma has a complex molecular basis, involving various cell-extracellular matrix and cell- cell interactions. We have previously shown that adhesion of colony- forming cells (CFC) to fibronectin, present in stromal extracellular matrix, involves multiple sites, including two heparin-binding synthetic peptides (FN-C/H I and FN-C/H II) and the alpha 4 beta 1 integrin-binding peptide CS1. These synthetic peptides are located in close proximity in the type III repeat 14 and the immediately adjacent type IIIcs region of fibronectin. In the current study, we evaluate receptors expressed by CFC responsible for their adhesion to fibronectin. We show that the alpha 4 beta 1 integrin mediates adhesion to CFC to the peptides FN-C/H I and CS1. Adhesion of CFC to fibronectin is also mediated by proteoglycans, because removal of cell surface chondroitin-sulfate proteoglycans resulted in decreased adhesion of CFC to FN-C/ I and FN-C/H II. The core protein of this proteoglycan was identified by immunoprecipitation as a 90-kD member of the CD44 group of adhesion molecules. Interestingly, although the proteoglycan core protein failed to adhere to FN-C/H II affinity columns, anti-CD44 monoclonal antibodies blocked CFC adhesion to FN-C/H II, indicating that these monoclonal antibodies may interfere with core protein- mediated intracellular signalling. Finally, we show that CD44 and alpha 4 beta 1 may cooperate in establishing progenitor adhesion, because anti-CD44 antibodies potentiated the adhesion-inhibitory effects of suboptimal concentrations of anti-alpha 4 or anti-beta 1 monoclonal antibodies. These results provide a working model for progenitor cell recognition of fibronectin (and possibly the marrow micro-environment) in which the coordinated action of integrins and cell surface proteoglycans is necessary for cell adhesion. This model can now be used to study the complex relationship between progenitor cell adhesion and the regulation of their proliferation and differentiation.     

A high-fat meal impairs muscle vasodilatation response to mental stress in humans with Glu27 β<Subscript>2</Subscript>-adrenoceptor polymorphism

Background  

Forearm blood flow responses during mental stress are greater in individuals homozygous for the Glu27 allele. A high-fat meal is associated with impaired endothelium-dependent dilatation. We investigated the impact of high-fat ingestion on the muscle vasodilatory responses during mental stress in individuals with the Glu27 allele and those with the Gln27 allele of the β₂-adrenoceptor gene.     

Haemoglobin S and haemoglobin C: 'quick but costly' versus 'slow but gratis' genetic adaptations to Plasmodium falciparum malaria

Haemoglobin S (HbS; beta6Glu-->Val) and HbC (beta6Glu-->Lys) strongly protect against clinical Plasmodium falciparum malaria. HbS, which is lethal in homozygosity, has a multi-foci origin and a widespread geographic distribution in sub-Saharan Africa and Asia whereas HbC, which has no obvious CC segregational load, occurs only in a small area of central West-Africa. To address this apparent paradox, we adopted two partially independent haplotypic approaches in the Mossi population of Burkina Faso where both the local S (S(Benin)) and the C alleles are common (0.05 and 0.13). Here we show that: both C and S(Benin) are monophyletic; C has accumulated a 4-fold higher recombinational and DNA slippage haplotypic variability than the S(Benin) allele (P = 0.003) implying higher antiquity; for a long initial lag period, the C alleles did apparently remain very few. These results, consistent with epidemiological evidences, imply that the C allele has been accumulated mainly through a recessive rather than a semidominant mechanism of selection. This evidence explains the apparent paradox of the uni-epicentric geographic distribution of HbC, representing a 'slow but gratis' genetic adaptation to malaria through a transient polymorphism, compared to the polycentric 'quick but costly' adaptation through balanced polymorphism of HbS.