Universal monoclonal antibody-based influenza hemagglutinin quantitative enzyme-linked immunosorbent assay

Seasonal and pandemic influenza infections remain a serious public health concern. Many health authorities recommend annual vaccination as the most effective way to control influenza infection. Accordingly, regulatory guidelines ask vaccine manufacturers to determine vaccine potency at the time of release and throughout shelf-life to ensure vaccine quality. The potency of inactivated influenza vaccine is related to the quantity of hemagglutinin (HA). Since 1970s, single radial immunodiffusion (SRID) assay has been standardly used for the quantitation of HA in influenza vaccine. However, SRID is labor-intensive, inaccurate, and requires standard reference reagents that should be updated annually. Therefore, there have been extensive efforts to develop alternative potency assays. In this study, we developed and tested a new HA quantitative enzyme-linked immunosorbent assay (ELISA) using a universal monoclonal antibody that can bind to HAs from various subtypes in group 1 influenza A virus (IAV). We analyzed the conserved stalk domain of HA via a library approach to design a consensus HA antigen for group 1 IAV. The antigens were expressed as a soluble form in E. coli and were purified by Ni-affinity chromatography. When tested with variety of HAs from IAVs or influenza B viruses (IBVs), the mAbs exhibited specific binding to group 1 HAs, with potential exception to H9 subtype. Among various conditions of pH, urea, and reducing agents, pretreatment of HA at low pH exposing the conserved stalk domain was crucially important for optimal ELISA performance. Calibration curves for various HAs were generated to determine accuracy, specificity, sensitivity, and linear dynamic range. The ELISA method shows high sensitivity and accuracy compared with the SRID assay. The HA group specific universal mAbs against the consensus stalk domain of HA are conducive to establishing an ELISA-based standard procedure for the quantitation of HA antigens for annual vaccination against influenza infection.     

Neighbourhood social fragmentation and the mental health of children in poverty

Using data from 7,776 Millennium Cohort Study children in England, we examined the role of neighbourhood social fragmentation in trajectories of emotional/behavioural problems at ages three, five and seven, and in moderating the association of children׳s emotional/behavioural problems with neighbourhood poverty, family poverty and adverse family events. Allowing for key background characteristics, social fragmentation generally added little to explain child outcomes, but there were fewer conduct problems among children in poor neighbourhoods with less fragmentation. Surprisingly, in less fragmented neighbourhoods poor families tended to feel less safe and more distressed, which was associated with children׳s conduct problems.     

Cardiac Implantable Electronic Devices in Patients With Left Ventricular Assist Systems

Recent progress and evolution in device engineering, surgical implantation practices, and periprocedural management have advanced the promise of durable support with left ventricular assist systems (LVAS) in patients with stage D heart failure. With greater uptake of LVAS globally, a growing population of LVAS recipients have pre-existing cardiac implantable electronic devices (CIEDs). Strategies for optimal clinical management of CIEDs in patients with durable LVAS are evolving, and clinicians will increasingly face complex decisions regarding implantation, programming, deactivation, and removal of CIEDs. Traditional decision-making pathways for CIEDs may not apply to LVAS-supported patients, as few patients die of arrhythmic causes and many arrhythmias may be well tolerated. Given limited data, treatment decisions must be individualized and made collaboratively among electrophysiologists, advanced heart failure specialists, and patients and their caregivers. Large, prospective, well-conducted studies are needed to better understand the contemporary utility of CIEDs in patients with newer-generation LVAS.     

Health-related quality of life trajectories among adults with tuberculosis: differences between latent and active infection

BACKGROUND: Tuberculosis (TB) remains a public health threat with significant annual impacts on morbidity and mortality. However, few studies have examined the impact of active and latent TB infection (LTBI) on health-related quality of life (HRQL). METHODS: Patients with recently diagnosed active TB or LTBI patients were administered the Short Form-36 (SF-36) and the Beck depression inventory (DI) at baseline, 3 months, and 6 months. Mixed-effect linear regression was used to compare the trajectory of HRQL over time in the two patient groups after adjusting for potential confounders. Ordinal logistic regression was used to determine the relationship between changes in HRQL of at least the minimal important difference. RESULTS: One hundred four active TB and 102 LTBI patients participated. At baseline, participants with active TB had significantly lower SF-36 mean domain and component scores (4 to 12 points lower, p < 0.03) and higher mean Beck DI scores (4 points higher, p < 0.0001) when compared to LBTI participants. In the responder analysis, those with active TB were associated with reporting improved scores at 6 months of at least the minimal important difference in vitality (odds ratio [OR], 2.7; 95% confidence interval [CI], 1.3 to 5.6), role physical (OR, 3.1; 95% CI, 1.4 to 6.5), mental component score (OR, 3.2; 95% CI, 1.5 to 6.9), social functioning (OR, 11.1; 95% CI, 3.8 to 33), and role emotional (OR, 2.7; 95% CI, 1.2 to 6.0). CONCLUSIONS: Active TB patients had large improvements in most HRQL domains by 6 months. However, when compared to LTBI participants and US norms, HRQL was still low at completion of therapy.     

Implantable left ventricular assist systems (LVAS): recent results. A report from a series of meetings sponsored by the Study Group on Advanced Heart Failure of the Working Group on Heart Failure

Implantable left ventricular assist systems (LVAS) consist of implantable pumps with small control consoles and power sources that can be worn externally. These systems provide far greater patient mobility and independence than external pumps with bulky control consoles. Patients with implantable LVAS can be discharged from hospital and are able to return to work and resume active sports. Most patients have received these systems as a bridge to heart transplantation. Clinical status and quality of life improve dramatically after device implantation and survival on support (60-70% after approx. 100 days of support) is acceptable compared with transplant candidates on medical therapy. Patient selection and adverse events, primarily bleeding, thromboembolism and infection, are important issues with LVAS. In the future, long-term support and bridging to myocardial recovery may become important indications for LVAS.     

Arterial Pulsatility and Circulating von Willebrand Factor in Patients on Mechanical Circulatory Support

BackgroundThe main risk factor for bleeding in patients with continuous-flow mechanical circulatory support (CF-MCS) is the acquired von Willebrand factor (VWF) defect related to the high shear-stress forces developed by these devices. Although a higher bleeding rate has been reported in CF-MCS recipients who had reduced pulsatility, the relation between pulsatility and the VWF defect has never been studied.ObjectivesThe purpose of this study was to investigate the relation between pulsatility and VWF under CF-MCS.MethodsWe assessed the effect of 2 CF-MCS on VWF multimer degradation in a mock circulatory loop (model 1). Using these devices, we investigated in a dose-effect model (model 2) 3 levels of pulsatility in 3 groups of swine. In a cross-over model (model 3), we studied the effects of sequential changes of pulsatility on VWF. We reported the evolution of VWF multimerization in a patient undergoing serial CF-MCS and/or pulsatile-MCS.ResultsWe demonstrated the proteolytic degradation of VWF multimers by high shear CF-MCS in a circulatory loop without pulsatility. We observed both in swine models and in a patient that the magnitude of the VWF degradation is modulated by the pulsatility level in the high shear-stress level condition, and that the restoration of pulsatility is a trigger for the endothelial release of VWF.ConclusionsWe demonstrated that the VWF defect reflects the balance between degradation induced by the shear stress and the endothelial release of new VWF triggered by the pulsatility. This modulation of VWF levels could explain the relationship between pulsatility and bleeding observed in CF-MCS recipients. Preservation of pulsatility may be a new target to improve clinical outcomes of patients.     

Reasons for Distress Among Burn Survivors at 6, 12, and 24 Months Postdischarge: A Burn Injury Model System Investigation

Objective

To identify important sources of distress among burn survivors at discharge and 6, 12, and 24 months postinjury, and to examine if the distress related to these sources changed over time.