Clostridium perfringens infections initially attributed to norovirus, North Carolina, 2010

We investigated an outbreak initially attributed to norovirus; however, Clostridium perfringens toxicoinfection was subsequently confirmed. C. perfringens is an underrecognized but frequently observed cause of food-borne disease outbreaks. This investigation illustrates the importance of considering epidemiologic and laboratory data together when evaluating potential etiologic agents that might require unique control measures.     

Minority HIV patients' perceptions of barriers and facilitators to participation in clinical research

HIV clinical trials play an essential role in producing new HIV medications, developing guidelines for the appropriate timing of antiretroviral treatment, and evaluating behavioral interventions that aim to increase the quality of life of HIV-infected individuals. It is critical to have participation from all demographic groups, yet minorities are disproportionately underrepresented in HIV clinical research. This study assessed HIV+ minority patient perceptions of the barriers and benefits of participating in HIV clinical trials in an HIV clinic of a large, urban teaching hospital. Twenty-six, age-eligible (18-65), minority patients were recruited and participated in three focus groups, separated by clinical research participation status. Results suggest differences in perceptions between those who had and had not participated. Facilitators for those who had participated included doctor recommendation and receiving extra medical attention. Those who had not participated indicated disclosure of HIV status, fear of losing the stability that their current medication regimen provided, distrust of the medical system and doubt about the origin of HIV were major deterrents of participation. Both groups indicated a need to better educate minority patients about what clinical research is and its benefits. To increase minority participation, it is vital to examine the perceptions of minority HIV-infected patients and develop culturally competent, developmentally appropriate messages that address these barriers.     

Variational model for a rippled graphene sheet

The calculus of variations is utilised to study the behaviour of a rippled graphene sheet supported on a metal substrate. We propose a model that is underpinned by two key parameters, the bending rigidity of graphene γ, and the van der Waals interaction strength ξ. Three cases are considered, each of which addresses a specific configuration of a rippled graphene sheet located on a flat substrate. The transitional case assumes that both the graphene sheet length and substrate length are constrained. The substrate constrained case assumes only the substrate has a constrained length. Finally, the graphene constrained case assumes only the length of the graphene sheet is constrained. Numerical results are presented for each case, and the interpretation of these results demonstrates a continuous relationship between the total energy per unit length and the substrate length, that incorporates all three configurations. The present model is in excellent agreement with earlier results of molecular dynamics (MD) simulations in predicting the profiles of graphene ripples.

A variational model is proposed to describe rippled graphene on a substrate, and obtain the relationship between total energy and substrate length.     

Heterogeneity of tibial plateau cartilage in response to a physiological compressive strain rate

Knowledge of the extent to which tibial plateau cartilage displays non‐uniform mechanical topography under physiologically relevant loading conditions is critical to evaluating the role of biomechanics in knee osteoarthritis. Cartilage explants from 21 tibial plateau sites of eight non‐osteoarthritic female cadaveric knees (age: 41–54; BMI: 14–20) were tested in unconfined compression at 100% strain/s. The elastic tangent modulus at 10% strain (E_10%) was calculated for each site and averaged over four geographic regions: not covered by meniscus (I); covered by meniscus—anterior (II); covered by meniscus—exterior (III); and covered by meniscus—posterior (IV). A repeated‐measures mixed model analysis of variance was used to test for effects of plateau, region, and their interaction on E_10%. Effect sizes were calculated for each region pair. E_10% was significantly different (p < 0.05) for all regional comparisons, except I–II and III–IV. The regional pattern of variation was consistent across individuals. Moderate to strong effect sizes were evident for regional comparisons other than I–II on the lateral side and III–IV on both sides. Healthy tibial cartilage exhibits significant mechanical heterogeneity that manifests in a common regional pattern across individuals. These findings provide a foundation for evaluating the biomechanical mechanisms of knee osteoarthritis. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 370–375, 2013     

Major complications related to epidural analgesia in children: a 15-year audit of 3,152 epidurals

Background

Complications associated with epidural analgesia in children have a reported incidence of 40-90 in 10,000 epidurals. We sought to determine the incidence of major complications with the use of continuous epidural analgesia that occurred in our centre over the past 15 years and to describe the nature of these complications.

Methods

The Acute Pain Service database at a tertiary care academic pediatric hospital was reviewed retrospectively over a 15-year period. Data were categorized according to patient age (neonate, infant, child one through eight years, and child > eight years), mode of insertion of the epidural (caudal, transsacral, lumbar, thoracic), complication type, and complication severity.

Results

Over the 15-year period, 3,152 epidurals were performed. The use of caudal-thoracic epidurals in neonates and infants has increased since 2007. Twenty-four major complications were identified (incidence, 7.6 in 1,000 epidurals). The rate of complications in neonates was 4.2% compared with 1.4% in infants, 0.5% in children aged one through eight years, and 0.8% in children over eight years of age. The two most common complications were local skin infection and drug error.

Conclusions

Our incidence of major complications and our finding that complications were more common in neonates and infants are both consistent with previously published data. The two most common types of complications are potentially preventable.