Mapping of the hepatitis B virus attachment site by use of infection-inhibiting preS1 lipopeptides and tupaia hepatocytes

BACKGROUND & AIMS: Studies on the early steps in the life cycle of hepatitis B virus have been hampered by the lack of readily available target cells. In this study, we mapped a defined virus attachment site to primary hepatocytes that is essential for infection. METHODS: We used purified virus particles from human carrier plasma as an inoculum and primary cultures of tupaia hepatocytes as susceptible target cells and studied the inhibitory effect of amino-terminally acylated preS1-derived lipopeptides on infection interference. RESULTS: Infectivity of virus could be blocked efficiently in this system by amino-terminally acylated peptides containing amino acids 2-18 from the preS1 domain. The addition of amino acids 28-48 enhanced the inhibitory capacity, whereas amino acids 49-78 did not contribute to inhibition. Myristoylated preS1 peptides 2-48 bound strongly to tupaia hepatocytes but not to nonhepatic cells or rodent hepatocytes and thereby inhibited infection even at concentrations of 1 nmol/L completely. Particles consisting only of the small hepatitis B surface protein-the active component of current hepatitis B vaccines-did not bind at all to tupaia hepatocytes, but the addition of the preS1 domain to the particles allowed binding. CONCLUSIONS: The preS1 sequence 2-48 mediates attachment of the virus to its target cells, whereas the small surface protein seems to be involved in other steps. These findings indicate that the current subunit hepatitis B vaccines may be improved by the addition of distinct preS1 epitopes. Moreover, preS1 lipopeptides are promising candidates for specific antiviral therapy against hepatitis B infections.     

EPA’s Stage 2 Disinfection Byproducts Rules (DBPR) and Northern Kentucky Water: An Economic and Scientific Review

Implementation of EPA’s Stage 2 Disinfection Byproducts Rules (DBPR) in Northern Kentucky will cause a water rate increase of over 25%. Hence a review was undertaken, considering both economics and science in the context of President Obama’s 2009 scientific integrity directive. The rules purport to avoid up to 0.49% of new bladder cancers by reducing the levels of DBPs in drinking water – a benefit so small that failure to implement will not cause unreasonable risk to health (URTH). It suggests at most one Northern Kentucky death avoided over 17 years for a cost of $136,000,000 ($1700 per household). Even this small benefit is probably overstated. EPA finds no “causal link” between DBPs and bladder cancer, and EPA acknowledges problems with the epidemiological data used in their calculation: the data appear contradictory and inconsistent, may be skewed toward “positive” results, and suggest different cancer sites than animal studies. Two similar international agencies disagree with EPA’s conclusions. The science is based on the Linear No Threshold (LNT) dose response model for DBPs, but this may not be the correct model. 83% of EPA’s epidemiological data show a statistical possibility that low levels of DBPs might be beneficial or have no effect.     

烟台市市政供水中三卤甲烷的污染状况

目的了解烟台市市政供水中4种三卤甲烷污染状况及季节性变化规律。方法对水源水、水厂水及管网末梢水中三氯甲烷、一氯二溴甲烷、一溴二氯甲烷、三溴甲烷的含量进行检测。结果目前烟台市市政供水4种三卤甲烷指标平均含量水平分别为25.2,22.9,14.8和7.9μg/L,未超出GB 5749-2006饮用水卫生要求,但管网水中一氯二溴甲烷浓度为19.2～24.6μg/L,含量偏高。结论目前烟台市市政供水中4种三卤甲烷污染状况不严重;其产生量随季节温度而变化,夏季最高,冬季最低。     

中美欧中药/植物药/传统草药质量标准差异分析

很多中药企业正在为中药的国际化进行着艰苦的努力,在中药国际化实践的进程中,自始至终存在的主要问题之一就是如何阐明中药质量的可控性和一致性,中药质量标准如何才能获得国际药政管理部门的认可。提升我国中药质量和质量标准是实现中药现代化和国际化的关键,同时只有识别差异才能缩短差距,通过分析中国、美国和欧盟对中药/植物药/传统草药质量标准的要求而对我国的中药研发和生产企业有所启示。     

中美欧中药/植物药/传统草药质量标准差异分析

很多中药企业正在为中药的国际化进行着艰苦的努力,在中药国际化实践的进程中,自始至终存在的主要问题之一就是如何阐明中药质量的可控性和一致性,中药质量标准如何才能获得国际药政管理部门的认可。提升我国中药质量和质量标准是实现中药现代化和国际化的关键,同时只有识别差异才能缩短差距,通过分析中国、美国和欧盟对中药/植物药/传统草药质量标准的要求而对我国的中药研发和生产企业有所启示。     

Comparison of trihalomethanes in tap water and blood: a case study in the United States

Background: Epidemiological studies have used various measures to characterize trihalomethane (THM) exposures, but the relationship of these indicators to exposure biomarkers remains unclear.Objectives: We examined temporal and spatial variability in baseline blood THM concentrations and assessed the relationship between these concentrations and several exposure indicators (tap water concentration, water-use activities, multiroute exposure metrics).Methods: We measured water-use activity and THM concentrations in blood and residential tap water from 150 postpartum women from three U.S. locations.Results: Blood ΣTHM [sum of chloroform (TCM), bromodichloromethane (BDCM), dibromo-chloromethane (DBCM), and bromoform (TBM)] concentrations varied by site and season. As expected based on variable tap water concentrations and toxicokinetic properties, the proportion of brominated species (BDCM, DBCM, and TBM) in blood varied by site (site 1, 24%; site 2, 29%; site 3, 57%) but varied less markedly than in tap water (site 1, 35%; site 2, 75%; site 3, 68%). The blood–water ΣTHM Spearman rank correlation coefficient was 0.36, with correlations higher for individual brominated species (BDCM, 0.62; DBCM, 0.53; TBM, 0.54) than for TCM (0.37). Noningestion water activities contributed more to the total exposure metric than did ingestion, but tap water THM concentrations were more predictive of blood THM levels than were metrics that incorporated water use.Conclusions: Spatial and temporal variability in THM concentrations was greater in water than in blood. We found consistent blood–water correlations across season and site for BDCM and DBCM, and multivariate regression results suggest that water THM concentrations may be an adequate surro-gate for baseline blood levels.