HIV－1Protease在大肠杆菌中的高表达

艾滋病的致病因子为人免疫缺陷病毒。该病毒的蛋白酶在病毒复制和成熟中具有决定性的意义。由于目前国内外尚未获得艾滋病病毒蛋白酶高效表达的重组子及简便的活性检测系统，限制了它的研究与应用。本文将用ＰＣＲ技术修饰的ＨＩＶＰｒ基因克隆入原核高效表达载体ｐＴＴＱ１８的ＥｃｏＲⅠ和ＨｉｎｄⅢ酶切位点之间，并用豆芽核酸酶将ＥｃｏＲⅠ的粘端削平，构建了读框正确的表达载体，ＩＰＴＧ诱导表明，该重组子在大肠杆菌中获得了高表达，激光扫描结果表明：重组的ＨＩＶＰｒ占细菌总蛋白８．９％以上。     

Thermogenesis due to noradrenaline in muscles under different rates of perfusion

Vascularly isolated hind legs of cold acclimated rats were perfused with arterial blood either without noradrenaline (NA) or with a constant concentration of NA (10 ng·ml^–1) at different perfusion rates ranging from 2 to 14l·g^–1·min^–1. The oxygen consumption of the leg during perfusion both with or without NA was linearly related to the perfusion rate. The linear increase of leg oxygen consumption with respect to the perfusion was steeper after NA, which indicates that the same arterial concentration of NA may produce a greater thermogenic effect at higher blood flow rates (the difference between resting metabolic rate and the thermogenesis stimulated by NA, was 8.20 l O₂·g^–1·h^–1 at a blood flow of 3l·g^–1·min^–1, compared with 45.02 l O₂·g^–1·h^–1 at a blood flow of 14 l·g^–1·min^–1). These data confirm the important role of the extravascular influx rate of NA in the control of thermogenesis due to NA in muscles.     

Partial purification and characterization of anhydrotetracycline oxygenase of Streptomyces aureofaciens

Anhydrotetracycline oxygenase was purified both by affinity chromatography and by hydrophobic interaction chromatography. Molecular weight of anhydrotetracycline oxygenase was determined to be 115,000 by Sephadex G-200 gel filtration. Using preparative isoelectric focusing the isoelectric point of the enzyme was estimated to be 5.3. The enzyme showed a sensitivity to thiol-specific inhibitors. During the hydrophobic interaction purification step, the activity dropped considerably. Reactivation occurred when a heat treated crude extract was added to the reaction mixture.     

Structure-intestinal transport and structure-metabolism correlations of some potential cancerostatic pyrimidine nucleosides in isolated rat jejunum

Summary Both transport and biotransformation processes for a series of pyrimidine nucleobases, ribonucleosides, 2-deoxyribonucleosides, and acetyl and 5-substituted derivatives of the cancerostatic agent araC were studied in the isolated everted rat jejunum with a continuous perfusion technique. Metabolic alterations during penetration were assessed by HPLC. 5-Halogeno and 5-deoxy derivatives of cytosine nucleosides exhibited higher transport rates and higher stability towards the deamination reaction than did unsubstituted derivatives. Octanol-buffer partition coefficients were estimated for the study compounds, and fragmental constants for the sugar moieties of nucleosides were assessed. With the present study compounds there was no correlation between lipophilicity and transport rate, as previously reported, but there was a correlation between lipophilicity and metabolic alteration of araC derivatives (r=0.99, n=5).     

Can Policy Promote Adoption or Outcomes of Evidence-based Prevention Programming?: a Case Illustration of Positive Behavioral Interventions and Supports

Prevention Science - This study examined the impact of a state policy requiring that any school with a habitual truancy rate of 8% or higher to be trained in Tier 1 school-wide Positive Behavioral...     

通州市医疗卫生单位消毒质量动态比较观察

对1997～2000年通州市医疗卫生单位消毒质量监测结果进行动态比较,显示消毒质量正在稳步提高,并以2000年为最佳,县级医疗卫生单位明显优于乡镇卫生院。     

饮食服务业从业人员乙型肝炎病毒感染动态研究

目的为了解泰安市饮食服务业从业人员乙型肝炎病毒感染状况。方法应用ELISA方法在1995～1999年对53434名饮食服务业从业人员进行了血清HBsAg、抗-HBc、HBeAg和抗-HBe检测。结果1995～1999年饮食服务业从业人员血清HBsAg、抗-HBc、HBeAg和抗-HBe总阳性率呈逐年下降趋势,依次为4.41%、3.88%、3.46%、2.86%和2.50%,其差异有显著意义（χ     

低铅染毒大鼠体内脂质过氧化及抗氧化水平改变

目的：观察低剂量铅染毒后大鼠体内脂质过氧化水平改变,为铅的毒作用机制研究提供依据。方法：以醋酸铅为受试物,雄性Wistar大鼠为受试对象,分别观察其脏器脂质过氧化水平改变。结果：低铅染毒后,大鼠各脏器超氧化物歧化酶（SOD）、谷胱苷肽过氧化物酶（GSH－Px）及过氧化脂质（LPO）均有不同程度改变（P＜0.05,P＜0.01）,而巯基（－SH）含量仅肝脏变化较明显。结论：较低剂量的铅即可引起体内脂质过氧化水平的改变,而这种变化可能是铅的毒作用途径之一。