中国广西狂犬病毒野毒株（CGX89－1株）糖蛋白基因核酸序列测定和分析

本文报告了中国广西狂犬病毒野毒株（ＣＧＸ８９－１株）糖蛋白基因ｃＤＮＡ的核苷酸序列及其推导的氨基酸序列。ＣＧＸ８９－１株的糖蛋白基因从起始密码ＡＴＧ到终止密码ＴＡＡ共有１５７５个核苷酸残基，可编码形成５２４个氨基酸残基的多肽链，经修饰后形成具有５０５个氨基酸残基构成的狂犬病毒糖蛋白。ＣＧＸ８９－１株的糖蛋白基因和核苷酸组成分别为：Ａ占２７．１１％，Ｔ占２６．２９％，Ｃ占２１．９７％和Ｇ占２４．６３％。核苷酸序列和巴斯德株（ＰＶ株），国际标准攻击毒株（ＣＶＳ株），中国狂犬病毒疫苗株（３ａＧ株）相比，同源性分别为８４．１％，８３．１％和８４．５％。其推导的氨基酸序列和ＰＶ株、ＣＶＳ株和３ａＧ株相比其同源性分别为９２．４％，８９．７％和８９．５％。ＣＧＸ８９－１株也具有３个Ｎ－糖基化位点，分别位于第３７位、１５７位和３１９位的氨基酸残基上。糖蛋白的膜外区部分重要抗原位点和ＰＶ株、ＣＶＳ株及３ａＧ株具有较高的一致性。     

Effects of methylphenidate on impulsive choice in adult humans

Rationale Several studies with nonhumans and humans have shown that stimulants decrease impulsive choices on delay-to-reinforcement (self-control) procedures. Little is known, however, about the effects of the stimulant methylphenidate on choice for delayed reinforcers in humans.Objectives The present study was designed to investigate the effects of acute methylphenidate administrations on impulsive responding in adult humans on a delay-to-reinforcement task.Methods Eleven adult males with a history of criminal behavior but no history of attention–deficit hyperactivity disorder (ADHD) participated. Impulsive responding was measured using an adjusting-delay procedure in which subjects were presented with repeated choices between a small amount of money delivered after a short delay and a larger amount of money delivered after a delay that adjusted as a function of previous choices. Subjects were exposed to four experimental sessions each day of participation and 60 min prior to the first daily session received placebo or 0.15, 0.30, or 0.60 mg/kg methylphenidate. Stable choice patterns were re-established between each methylphenidate dose.Results Individuals differed in their sensitivity to methylphenidate, but in over half of the subjects methylphenidate decreased impulsive (i.e., increased the number of self-control choices) and increased the delay to the large reinforcer. The largest increases in self-control choices tended to occur at the 0.30-mg/kg and 0.60-mg/kg doses, and the effects often persisted across multiple daily sessions. In six subjects, under at least one methylphenidate dose, the number of impulsive choices decreased to zero.Conclusions Acute methylphenidate administrations tended to decrease the number of impulsive choices in adult humans on an adjusting-delay procedure, although there were substantial individual differences in the sensitivity of choice to methylphenidate. In no case, however, did methylphenidate increase impulsive choices. These results are consistent with several recent laboratory studies with nonhumans and humans showing that stimulants increase preference for large, delayed reinforcers.