Effects of the pyrimidine-containing cytochrome P-450 inhibitor,fenarimol, on the formation of 20-OH ecdysone in flies

Summary The effect of fenarimol, a pyrimidine-containing cytochrome P-450 inhibitor, was tested in vitro on brain-ring gland complexes ofCalliphora vicina (Dipt., Calliphoridae), and on microsomes prepared from the fat body of 0-h wandering stage larvae ofNeobellieria bullata (Dipt., Sacrophagidae). Fenarimol had no influence on the formation of ecdysone, but it was an effective inhibitor of cytochrome P-450-dependent ecdysone 20-monooxygenase.     

Ecdysteroid conjugates in the ovaries of the silkworm,Bombyx mori: 3-phosphates of 2,22-dideoxy-20-hydroxyecdysone and of bombycosterol

Summary Two novel ecdysteroid conjugates, 2,22-dideoxy-20-hydroxyecdysone 3-phosphate (1) and bombycosterol 3-phosphate (2), as well as four known ecdysteroid 22-phosphate esters, have been isolated and characterized from the ovaries of the silkworm,Bombyx mori.     

氢在20Mn2TiB钢应力腐蚀中的作用

20Mn_2TiB钢制试样充氢后,分别进行拉伸试验,氢对机械性能的影响;单悬臂试验,测定试验用钢在不同介质中的K_(1scc),并讨论氢在scc中的作用;双悬臂试验,探讨所用材料在不同介质、不同温度,不同K值时da/dt的变化规律,并求出裂纹扩展的激活能Q。     

Antioxidant and prooxidant roles of copper in Tween 20-induced hemolysis of hamster and pig erythrocytes containing marginal vitamin E

The concentration-dependent effects of copper acting either as an antioxidant or as a prooxidant were examined in vitro using Tween 20-induced hemolysis. When cupric ion concentration was more than 10 M, free copper(II) acted as a prooxidant; both extensive hemolysis and production of unknown thiobarbituric acid-reactive substance occurred in hamster and pig erythrocytes irrespective of vitamin E status. However, when cupric ion concentration was 2–4 M in the incubation medium, copper showed a clear antioxidant activity, reducing both hemolysis and malondialdehyde production induced either by diluted peroxide-containing Tween 20 with ascorbic acid and sodium azide in vitamin E-deficient hamster erythrocytes, or by peroxide-containing Tween 20 in pig erythrocytes containing marginal amounts of vitamin E. Copper(II) is taken up by the erythrocytes, where copper(I)-complexes may contribute to the protection of cells with membrane vitamin E against oxidative radical attack.     

Insect hormones in vertebrates: Anabolic effects of 20-hydroxyecdysone in Japanese quail

Ecdysteroids are hormones controlling cell proliferation, growth and the developmental cycles of insects and other invertebrates¹. They are occasionally present in various unrelated plants for no apparent reason; no phytohormonal function has yet been identified. In certain cases, ecdysteroids are accumulated to high levels in leaves, roots or seeds. Some ecdysteroid-containing plants have been known as medicinal plants for centuries. One of them,Leuzea carthamoides Iljin (Asteraceae), growing in Central Asia, contains 0.4% ecdysteroid in dry roots and 2% in seeds. A pharmacological preparation from this plant, Ecdisten, is already available as a commercial preparation for its anabolic, tonic and other effects, for medical use (review²). It remained problematic, however, whether ecdysteroids were truly responsible for these effects, becauseLeuzea contains a number of other biologically active compounds in addition to ecdysteroids. We extracted and purified ecdysteroids from the seeds ofLeuzea. With 6 g of 96% 20-hydroxyecdysone (20E), we made a large-scale feeding assay with Japanese quail to find out whether ecdysteroid alone could duplicate the anabolic effects of the seeds. We found that the 96% ecdysteroid increased the mass of the developing quails in a dose-dependent manner, with the rate of increase proportional to the ecdysteroid content in the seeds; there was a 115% increase in living mass with 100 mg kg^–1 of pure 20E compared with 109.5% increase with 100–180 mg kg^–1 20E equivalents in the seeds. We conclude that the plethora of growth-promoting, vitamin-like effects induced in vertebrates byLeuzea is mediated by ecdysteroids.     

20世纪后半期东盟国家与苏联的关系

在20世纪后半期的亚太国际关系史上,东盟国家与苏联的关系是二战后全球冷战的一个侧面,是大国关系和地区利益交汇的体现.这段历史可分为三阶段：印支战争结束前的有限交往;印支战争结束后的加强扩张和20世纪80年代中期的关系改善;苏联解体后的正常交往.东盟国家在与苏联的双方关系中处于主导地位,特别是20世纪80年代以后.     

基于单片机的电子日历设计

基于8位单片机进行的电子日历设计,在显示时间温度的基础上,可调整日期和时间、设置闹钟等功能.首先介绍该设计的总体设计方案,接着分别从硬件和软件两方面介绍设计过程,最后对仿真过程中遇到的问题做一个总结.     

期刊借阅的行为分析——以浙江图书馆为例

以浙江图书馆为研究案例,对该馆期刊外借的有关数据如借阅量、读者构成等进行了数据挖掘和统计分析,阐述了期刊借阅和读者存在的“二八现象”,比较了电子期刊与纸质期刊的异同.