从Staphylococcus simulans消除含有溶葡球菌酶基因质粒的研究

溶葡球菌酶是Staphylococcus simulans分泌的能分解葡萄球菌的酶,它的基因位于一个约40kb的质粒DNA上。为了探索用高拷贝质粒取代原有的质粒的可能性,本文首先进行了从该菌株中消除含有溶葡球菌酶基因质粒的实验研究,获得了相应的“消除”菌株。根据对目的菌株和原始菌株的比较分析,包括细胞蛋白质的SDS-聚丙烯酰胺凝胶电泳,Western blot分析,质粒DNA的琼脂糖胶电泳、Southern Blot分析,质粒DNA的限制性内切核酸酶酶切分析以及对溶葡球菌酶作用敏感性的分析,都表明该目的菌株确系Staphylococcus simulans的衍生菌株,只是清除了其中含有溶葡球菌酶基因的质粒。在此基础上,本文也进行了转化实验。     

银鲫精子在两性融合生殖鱼类卵质中的受精特征

红鲤(♀)×银鲫(♂)的杂种胚胎均不能成活。受精细胞学研究结果表明,雌核发育银鲫的精核在两性融合生殖的鲤鱼卵质中能转化为雄性原核,并和雌性原核融合成合子核。但在卵裂开始后,可观察到某些异常现象,如染色体丢失,多极纺锤体形成,以及第二次卵裂时受精卵的两分裂球的非同步性分裂等。我们初步认为,雌核发育银鲫的染色体和两性融合生殖的鱼类染色体之间存在某种不相容性,表现为彼此间的互相排斥。出现这种现象可能和银鲫染色体组的雌核发育遗传背景有关。     

Syntheses of di-hydrocarbyl derivatives of carbonyl phosphine complexes of iron

Complexes cis,trans-Fe(CO)₂(PMe₃)₂RR′ (R = CH₃, R′ = Ph (2); R = CH₃, R′ = CHCH₂ (3); R = CHCH₂, R′ = Ph (4); R = R′ = CHCH₂ (5); R = R′ = CH₃ (6)) were prepared by reaction of cis,trans-Fe(CO)₂(PMe₃)₂RCl (1) with organolithium reagents LiR′. All complexes were characterized in solution by IR and ¹H, ³¹P and, in a few cases, ¹³C NMR mono- and bi-dimensional spectroscopies. Complexes 5 and 6 were structurally characterized by X-ray diffractometric methods. In solution complexes 2, 3 and 4 undergo slowly coupling of the σ-hydrocarbyl substituents leading to Fe(CO)₃(PMe₃)₂ and other decomposition products. Complex 6 was very stable in solution in the absence of nucleophiles and in the solid state. Complex 5 transformed through intramolecular coupling of the vinyl groups into Fe(CO)(PMe₃)₂(η⁴-butadiene) (7), which was characterized in solution by IR and NMR spectroscopies.     

Use of 11alpha-deuterium labeled cortisol as a tracer for assessing reduced 11beta-HSD2 activity in vivo following glycyrrhetinic acid ingestion in a human subject

This study describes an oral administration of 5 mg of [1,2,4,19-13C4,11alpha-2H]cortisol (cortisol-13C4,2H1) to a human subject performed on two separate occasions, one with cortisol-13C4,2H1 alone and the other with cortisol-13C4,2H1 plus 130 mg per day of glycyrrhetinic acid for 6 days. The stable isotope methodology employed allowed for the evaluation of the individual in vivo activities of the two isozymes of 11beta-hydroxysteroid dehydrogenase (11beta-HSD), 11beta-HSD1 and 11beta-HSD2, and to demonstrate the sensitivity of changes in cortisol elimination half-life for detecting inhibition of 11beta-HSD2 activity induced with glycyrrhetinic acid. The kinetic analysis associated with the loss of 11alpha-2H during the conversion of cortisol-13C4,2H1 to cortisone-13C4 by 11beta-HSD2 clearly indicated reduced 11beta-HSD2 activity with glycyrrhetinic acid ingestion, as observed by an increase in the elimination half-life of cortisol-13C4,2H1. The elimination half-life of cortisol-13C4,2H1 provided sensitive in vivo measures of 11beta-HSD2 activity and was more sensitive for detecting changes in renal 11beta-HSD2 activity than the measurement of the urinary ratio of free cortisol and free cortisone (UFF/UFE). The 2H-labeling in the 11alpha-position of cortisol served as an appropriate tracer for assessing the reduced 11beta-HSD2 activity in vivo induced by glycyrrhetinic acid.     

Controlling emerging infectious diseases like SARS

To control emerging infectious diseases like SARS, it is necessary to resort to basic control measures that limit exposures to infectious individuals. These measures include isolating cases at diagnosis, quarantining household members and tracing contacts of diagnosed cases, providing the community with advice on how to reduce exposures, and closing schools. To justify such intervention it is important to understand how well each of these measures helps to limit transmission. In this paper, we determine the effect of a number of different interventions on the effective reproduction number and estimate requirements to achieve elimination of the infectious disease. We find that the strategy of tracing and quarantining contacts of diagnosed cases can be very successful in reducing transmission.     

分支格局、组份分析与中值淘汰法

文章简明介绍了现代分支系统学的分支格局原理和组份分析方法,并应用于李朝銮(1990,表2)的中国白粉藤属14种植物数据的分支分析。得出13个可能的最简约的二歧分支图,图长41步。这些分支图与李(1990)图2：13的比较表明,中值淘汰法不如组份分析方法有效,而且中值淘汰法有表相学和(或)进化系统学的疑问。     

脱氧雪腐镰刀菌烯醇(CBD1)在大鼠的分布、转归和动力学研究

用~3H-CBD_1灌胃Wistar大鼠,研究其吸收、分布和转归。~3H-CBD_1迅速经胃肠道吸收,5分钟后血中即可测得放射性。血液时间-放射性曲线呈双峰,峰值分别为半小时和12小时。达峰值后血中放射性逐渐下降,生物半衰期6.33天。除胃肠道外,肝、肾、脑、睾丸放射性较高。肝、肾为其主要代谢和排泄器官。24小时内尿排出灌胃量的16.2％,粪排出7.5％。7天尿、粪共排出41.4％,14天排出43％。 CBD_1的吸收和排泄符合二室动力学模型。动力学参数如下:T_(1/2α)0.6858天,T_(1/2β)6.3330天,T_(1/2Ka)0.2342天,t_p 0.375天,Ka 2.9595天~(-1),V_1 1663ml,V_2 887ml,V_D(ss)2551ml。相关系数0.978。由此可见~3H-CBD_1自胃肠道吸收迅速;分布于全身组织器官,没有特殊的蓄积器官;排泄较慢;与动力学分析结果相符。     

我们离麻疹消除还有多远?

中国麻疹发病率自2008年起出现大幅度下降,但2012年底以来麻疹发病疫情呈上升趋势,部分城市出现了以成人为主的疫情暴发。导致麻疹疫情再次上升的一个可能原因是中国的麻疹疫苗实际接种率低于报告接种率,常规免疫有不到位的情况。同时,中国存在部分麻疹免疫空缺人群,既未接种过麻疹常规疫苗,也没有参加过2004—2010年的补充免疫活动。这类人群积累到一定程度后,可引起聚集性的疫情暴发。中国在消除麻疹方面虽已取得显著进展,但近年来疫情再次抬头值得警惕。进一步增加常规麻疹两剂疫苗接种率,对重点地区和人群适当增加补充免疫活动,更好地落实麻疹应急预案等,将有助于控制并消除麻疹疫情。     

Road to the elimination of schistosomiasis from Asia: the journey is far from over

Schistosomiasis is a neglected tropical disease with a very long endemic history in Asia. Great strides have been made to control the disease in China and the Philippines but the road to elimination is far from over, given the zoonotic nature of the schistosome parasites in both countries.