Low level occupational exposure to styrene: its effects on DNA damage and DNA repair

The present study aimed to evaluate the effects of styrene exposure at levels below the recommended standards of the Threshold Limit Value (TLV-TWA(8)) of 20 ppm (ACGIH, 2004) in reinforced-fiberglass plastics workers. Study subjects comprised 50 exposed workers and 40 control subjects. The exposed workers were stratified by styrene exposure levels, i.e. group I (<10 ppm, <42.20 mg/m(3)), group II (10-20 ppm, 42.20-84.40 mg/m(3)), and group III (>20 ppm, >84.40 mg/m(3)). The mean styrene exposure levels of exposed workers were significantly higher than those of the control workers. Biomarkers of exposure to styrene, including blood styrene and the urinary metabolites, mandelic acid (MA) and phenylglyoxylic acid (PGA), were significantly increased with increasing levels of styrene exposure, but were not detected in the control group. DNA damage, such as DNA strand breaks, 8-hydroxydeoxyguanosine (8-OHdG), and DNA repair capacity, were used as biomarkers of early biological effects. DNA strand breaks and 8-OHdG/10(5)dG levels in peripheral leukocytes of exposed groups were significantly higher compared to the control group (P<0.05). In addition, DNA repair capacity, determined by the cytogenetic challenge assay, was lower in all exposed groups when compared to the control group (P<0.05). The expression of CYP2E1, which is involved in styrene metabolism, in all styrene exposed groups, was higher than that of the control group at a statistically significant level (P<0.05). Levels of expression of the DNA repair genes hOGG1 and XRCC1 were significantly higher in all exposed groups than in the control group (P<0.05). In addition to styrene contamination in ambient air, a trace amount of benzene was also found but, the correlation between benzene exposure and DNA damage or DNA repair capacity was not statistically significant. The results obtained from this study indicate an increase in genotoxic effects and thus health risk from occupational styrene exposure, even at levels below the recommended TLV-TWA(8) of 20 ppm.     

Interstitial cells from dogs with naturally occurring myxomatous mitral valve disease undergo phenotype transformation

BACKGROUND AND AIM OF THE STUDY: Myxomatous mitral valve disease is a common naturally occurring heart disease of dogs that is pathologically similar to myxomatous mitral valve disease in humans. It was hypothesized that interstitial cell phenotype transformation recently described in human myxomatous valves might also occur in dogs with myxomatous mitral valves, and correlate with disease severity. METHODS: Normal and early-, intermediate- and late-stage myxomatous canine mitral valves were examined histologically and immunohistochemically for cytoskeletal (vimentin, desmin, smooth muscle alpha-actin, smooth muscle myosin, and non-muscle myosin), collagenolytic (MMP-1, MMP-13), cell surface (CD-31, CD-45, CD-68) and proliferation (Ki-67) proteins. RESULTS: Normal canine mitral valve interstitial cells were positive for vimentin, but negative for alpha-actin, desmin and non-muscle myosin (i.e., fibroblast phenotype). Interstitial cells from myxomatous valves showed progressive positive staining for alpha-actin and desmin, but were negative for smooth muscle myosin (i.e., myofibroblast phenotype). Positive-staining cells first appeared as cellular clusters in the subendocardial region of the lamina atrialis and extended into deeper layers with increasing severity. Interstitial cells from myxomatous valves showed positive staining for non-muscle myosin (i.e., activated mesenchymal cell phenotype). Positive-staining cells increased with disease severity and were dispersed throughout the valve layers. The expression of MMP-1 and MMP-13 increased in myxomatous mitral valves and correlated with disease severity. Interstitial cellularity increased dramatically in degenerative mitral valves, though Ki-67 staining was only mildly increased. CONCLUSION: Two patterns of interstitial cell phenotype transformation were identified in dogs with myxomatous mitral valve disease, and both correlated with disease severity. Myofibroblast transformation characterized by positive staining for alpha-actin and desmin occurred in cellular clusters primarily in the lamina atrialis. Mesenchymal cell activation characterized by positive staining to non-muscle myosin occurred throughout the valve. The dog may be a natural model for studying the cell biology of progressive myxomatous valve disease.     

Pseudo-Arclength Continuation Algorithms for Binary Rydberg-Dressed Bose-Einstein Condensates

We study pseudo-arclength continuation methods for both Rydberg-dressed Bose-Einstein condensates (BEC), and binary Rydberg-dressed BEC which are governed by the Gross-Pitaevskii equations (GPEs). A divide-and-conquer technique is proposed for rescaling the range/ranges of nonlocal nonlinear term/terms, which gives enough information for choosing a proper stepsize. This guarantees that the solution curve we wish to trace can be precisely approximated. In addition, the ground state solution would successfully evolve from one peak to vortices when the affect of the rotating term is imposed. Moreover, parameter variables with different number of components are exploited in curve-tracing. The proposed methods have the advantage of tracing the ground state solution curve once to compute the contours for various values of the coefficients of the nonlocal nonlinear term/terms. Our numerical results are consistent with those published in the literatures.     

Modeling of AIDS incidence and the response of transmission rates to increase prevention effort: a case study of the Thai province of Nakhon Pathom

AIDS is a serious public health problem. Our projections of the likely incidence of AIDS are of vital importance to the assessment of future healthcare needs. This paper considers an epidemic model of the population dynamics of AIDS, which has been adjusted to take into account the changes in the transmission rate in response to changes in risk behaviors and increased AIDS awareness due to public health policy, AIDS campaigns, and other means of disease prevention. The model, adjusted for reporting delays and for the variable incubation period of the disease, has been applied to AIDS incidence data gathered in Nakhon Pathom, Thailand. Using the least-squares criterion, we solved for the appropriate values of the parameters which gave the best fit of the model to the observation data. The model was found to be capable of generating short-term projections, and offers an explanation for the decline in the number of cases that is evident in more recent data.     

Trends and inequities in where women delivered their babies in 25 low-income countries: evidence from Demographic and Health Surveys

In low-income countries, the coverage of institutional births is low. Using data from the two most recent Demographic and Health Surveys (1995–2001 and 2001–2006) for 25 low-income countries, this study examined trends in where women delivered their babies – public or private facilities or non-institutional settings. More than half of deliveries were in institutional settings in ten countries, mostly public facilities. In the other 15 countries, the majority of births were in women's homes, which was often their only option. Between the two survey periods, all five Asian countries studied (except Bangladesh) had an increase of 10–20 percentage points in institutional coverage, whereas none of the 19 sub-Saharan African countries saw an increase of more than 10 percentage points. More urban women and more in the richest (least poor) quintile gave birth in public or private facilities than rural and poorest quintile women. The rich–poor gap of institutional births was wider than the urban–rural gap. Inadequate public investment in health system infrastructure in rural areas and lack of skilled health professionals are major obstacles in reducing maternal mortality. Governments in low-income countries must invest more, especially in rural maternity services. Strengthening private, for-profit providers is not a policy choice for poor, rural communities.     

N-linked glycosylation in C2 region of HIV-1 envelope reduces sensitivity to neutralizing antibodies

N-linked glycosylation at specific sites on human immunodeficiency virus (HIV)--1 gp120 envelope glycoprotein is believed to act as a glycan shield to protect the viral neutralizing epitopes. Various glycosylation sites have been shown to affect the sensitivity to antibody-mediated neutralization. These include sites on V1V2, C2, base of V3, V5 and C5. Among these, the sites around the base of V3 loop have been most consistently found to associate with neutralization sensitivity in subtype B viruses. In contrast, we found that N-linked glycosylation sites at the junction of V2--C2 and in the middle of C2 were responsible for the neutralization resistance in CRF01_A/E, whereas sites at the base of V3 loop and in V1 and V5 did not affect the neutralization phenotype.