Analysis of the Streptococcal Hemoprotein Receptor: A Role in Virulence and Host Defense

Group A streptococcus (GAS) is an important pathogen that produces a wide spectrum of suppurative infections and autoimmune sequelae in humans, ranging from less complex pharyngitis, impedigo to more severe manifestations such as necrotizing fasciitis, toxic shock syndrome, rheumatic fever and glomerulonephritis. The worldwide burden of GAS infections and sequelae is considerable, but an immunization program that defends against the hyper-variable GAS is missing. The streptococcal hemoprotein receptor (Shr), is an iron-regulated protein involved in heme acquisition. An unspecified region in the amino terminus of Shr mediates the interactions with hemoglobin and two protein modules named NEAT1 and NEAT2 bind heme. In this study, we analyzed the molecular structure and function of Shr, investigated its antigenic properties and role in GAS disease production. We demonstrated that Shr is a new type of GAS adhesin that contributes to the pathogen interactions with extracellular matrix (ECM) proteins. Shr enabled bacterial adherence to host cells and was important for GAS virulence in vivo. Immunizations with Shr protein by intraperitoneal or intranasal administration conferred resistance to systemic GAS challenge in mice. Shr antiserum allowed bacterial opsonization and defended against GAS diseases in a murine model for passive vaccination. Studies with isolated Shr domains localized ECM-binding to the NEAT domains and showed that most of the protein is exposed on the bacterial surface. In addition, Shr N-terminal region and both of the NEAT modules elicited strong antibody response in rabbits. In conclusion, Shr is a protective antigen that contributes to GAS pathogenesis by facilitating both heme uptake and bacterial adherence. Since Shr is conserved among GAS strains and other pyogenic streptococci, this study demonstrates that Shr may be used to develop a vaccine against GAS strains and related pathogens

Fertility and the user cost of home ownership : Evidence from regional panel data

Cross-sectional data yield the interesting result that fertility rates and home ownership rates tend to correlate positively, while time-series data suggest an inverse (or no) relationship between them. Although these associations can be explained by observed economic variables, doubt remains as to whether these links are due to the existence of omitted regional and time effects. Thus, controlling for regional-specific fixed effects and nationwide common time effects, this paper tests the link between the user cost of home ownership, which is the purchase price of housing, and total fertility rates. The empirical results, which use a panel of Japanese regional aggregate data, suggest that the impact of user costs on fertility considerably decreased when compared with the pooled OLS regression result without controlling for the above effects, but remained significantly negative. In the Japanese context, the association between the number of children and home ownership seems to be complementary

THE COMPARISON OF GAIT CHARACTERISTICS BETWEEN OLDER TAI-CHI CHUAN PRACTITIONERS AND NON PRACTITIONERS

INTRODUCTION: Tai-Chi Chuan (TCC) is a traditional Chinese exercise, which recently has become popular in the western world. The reported benefits of TCC exercise, include increased lower extremity muscle strength, improved balance, improved cardiopulmonary function, and improved overall wellness (Koh T.C., 1981). However, up to the present time, there have been no studies that have proven the effects of TCC exercise on walking performance. The purpose of this study is to determine whether or not TCC exercise has a beneficial effect on the normal speed of walking in older adults

Observation and management of shallow anterior chamber after glaucoma surgery

AIM: To analyze the cause and management of shallow anterior chamber after glaucoma surgery.<p>METHODS: The cause and management of shallow anterior chamber after glaucoma surgery on 298 cases(462 eyes)were analyzed retrospectively.<p>RESULTS: In 298 cases(462 eyes), 99 eyes(21.4%)had shallow anterior chamber. In 358 eyes treated with trabeculectomy, 77 eyes(21.5%)had shallow anterior chamber. In 85 eyes treated with trabeculectomy+MMC(mitomycin C), 20 eyes(23.5%)had shallow anterior chamber. In 19 eyes treated with trabeculectomy combined with cataract phacoemulsification and intraocular lens implantation, 2 eyes(10.53%)had shallow anterior chamber. Shallow anterior chamber appeared at 1 day to 5 days postoperatively. Forty-two eyes(42.4%)were with excessive filtering, 6 eyes(6.1%)with malignant glaucoma, 29 eyes(29.3%)with choroidal detachment, 2 eyes(2.0%)with malignant glaucoma complicated by choroidal detachment. Of 99 eyes with shallow anterior chamber, anterior chamber of 79 eyes recovered treated by nonsurgical methods, 20 eyes treated by operation.<p>CONCLUSION: The common cause of shallow anterior chamber after glaucoma surgery was preoperative high intraocular pressure, inflammation, excessive filtering, conjunctival flap flushing and choroidal detachment. Most cases can be managed with nonsurgical methods. Surgical interference should be taken if necessary

Error Analysis of Virtual Element Methods for the Time-dependent Poisson-Nernst-Planck Equations

We discuss and analyze the virtual element method on general polygonal meshes for the time-dependent Poisson-Nernst-Planck equations, which are a nonlinear coupled system widely used in semiconductors and ion channels. The spatial discretization is based on the elliptic projection and the $L^2$ projection operator, and for the temporal discretization, the backward Euler scheme is employed. After presenting the semi and fully discrete schemes, we derive the a priori error estimates in the $L^2$ and $H^1$ norms. Finally, a numerical experiment verifies the theoretical convergence results