Synthesis and antiplatelet, antiinflammatory, and antiallergic activities of 2-substituted 3-chloro-1,4-naphthoquinone derivatives

A series of 2-substituted 3-chloro-1,4-naphthoquinones was synthesized, and the antiplatelet, antiinflammatory, and antiallergic activities of these compounds were evaluated. The structure-activity relationships in this series were also examined. Most of the 2-alkyl/arylcarboxamido derivatives of 3-chloro-1,4-naphthoquinone showed potent activities with similar trends in each of the activities evaluated.     

神经生长因子结构与功能研究进展

神经生长因子(NGF)是神经营养因子家族的典型代表, 它控制着脊椎动物周围和中枢神经系统中部分神经元的发育和存活.NGF的三维结构是以“胱氨酸结”和β折叠为基础,它以二聚体的形式结合细胞表面的受体从而发生生物学效应.参与这些反应的氨基酸残基已通过化学修饰和定点突变法加以确定,这有助于更进一步理解其结构与功能的关系.     

Some applications of reversed-phase high-performance liquid chromatography to oligosaccharide separations

Oligosaccharide separation on reversed-phase high-performance liquid chormatographic columns have been examined using a range of aqueous solvents. Addition of anionic, cationic and non-ionic surfactants, tetramethyl urea and organic solvents to the mobile phase cause faster elution of oligosaccharides, and allow the separation of the larger oligomers in an acceptable time. Addition of neutral, inorganic salts increase the retention factors considerably, and allows good resolution of some compounds poorly resolved in water alone.The mechanism operating in the separations approximates to that invoked in the solvophobic theory of reversed-phase chromatography. There is some evidence also of hydrogen bond effects. The improvements described should prove useful in the isolation and analysis of neutral oligosaccharides in general, and in structural analyses of polysaccharides in paritcular.     

Studies on sex-organ development. Oestrogenic effect on ornithine decarboxylase activity in the differentiating Müllerian ducts and other organs of the chick embryo.

The activity of ornithine decarboxylase in the differentiating left and right Müllerian ducts was assayed and compared with that in other embryonic organs, i.e. the liver and the brain throughout the stages of development. In general the enzyme activity was high in the early stages and decreased extensively in the late stages of development. Specifically, in the left and righ Müllerian ducts, the enzyme activity was high from day 8 to day 9 of incubation. In the right duct the enzyme activity started to decline on day 9 and then continuously decreased to an almost undetectable value on day 18 of incubation. In the left duct the enzyme activity also decreased slightly from day 9 to day 12; however, it increased from day 13 to day 15 and finally decreased to a constant value from day 18 until hatching. The alteration in enzyme activity in the Müllerian duct as assayed in vitro during development is not due to the effect of the size of the endogenous ornithine pool. When the enzyme activity was subjected to oestrogen stimulation, an increase of 5--10-fold for the left duct and of 5--3-fold for the right duct was observed during the course of development. No such stimulation was observed with the treatment of progesterone. Testosterone consistently caused a 25--30% inhibition of the enzyme activity in the Müllerian duct. Oestrogen slightly stimulated the enzyme activity in the developing liver but inhibited that of the brain. The concentration of the three polyamines measured in the Müllerian duct corresponds to the activity of the enzyme determined.     

Studies on sex-organ development. Changes in nuclear and chromatin composition and genomic activity during spermatogenesis in the maturing rooster testis.

We developed a technique to separate nuclei of rooster testis by centrifugation through a discontinuous sucrose density gradient and by sedimentation at unit gravity. Four different major fractions obtained from testicular nuclei and one from the vas deferens were characterized according to their velocity of sedimentation, morphology and DNA content. The ratios (w/w) of basic proteins, non-histone proteins and RNA to DNA decreased during spermiogenesis both in nuclei and chromatin. Changes in the electrophoretic patterns of histones and non-histone proteins were detected especially in the elongated spermatids. The lack of uptake of [3H]uridine in elongating and elongated spermatids and in spermatozoa was demonstrated by radioautography and by the detection of labelled RNA extracted from different fractions of nuclei. Template activity for RNA synthesis and the binding of actinomycin D by testicular nuclei reached a peak in the elongated spermatid stage, when the histones are replaced by the protamine.     

Evidence that the regulation of diphtheria toxin production is directed at the level of transcription.

It has been known for several decades that iron inhibits the production of diphtheria toxin by Corynebacterium diphtheriae by preventing expression at maximal levels. We examined the inhibition kinetics of toxin production after the addition of either iron or rifampin to iron-limited cultures of C7 (betatox+). Iron-mediated inhibition of toxin production was found to be linear within the range of 16 nM to 16 micron. The inhibition kinetics following the addition of iron or rifampin was almost identical. [3H]RNA extracted from iron-limited toxigenic C. diphtheriae was found to hybridize to a greater extent to corynephage beta DNA than either [3H]RNA extracted from toxigenic C. diphtheriae before the onset of toxin production or [3H]RNA extracted from nonlysogenic, nontoxigenic C. diphtheriae.     

兰属(Cymbidium)5种植物叶结构特征

采用光学显微镜和体视镜,对兰属5种植物（春兰、蕙兰、建兰、寒兰、墨兰）的叶结构特征（叶脉结构、叶表皮结构、解剖结构）进行了观察和测量。结果显示,兰属5种植物的叶脉结构相似,叶表皮结构和解剖结构存在较大差异,其中最主要的差异是皮下纤维束的多少和边缘角质层锯齿形态。依据叶结构特征聚类分析结果,5种兰可分为春兰组、建兰组和墨兰组3组。本研究表明叶结构特征对兰属5种植物的分类具有重要意义。