The vanishing twin: An explanation for discordance between chorionic villus karyotype and fetal phenotype

One ‘erroneous’ diagnosis occurred in 200 first-trimester chorionic villus samples (CVS) analysed. In direct preparations following 24 h incubation as well as in long-term cultures, a 46.XX karyotype was observed in the villi (28 and 25 cells, respectively). At 20 weeks of gestation, labour was induced because of fetal death in utero. An autopsy performed on the fetus revealed a male phenotype. Placenta and fetal tissues were not submitted for cytogenetic studies. The discordant CVS karyotype (46,XX), in view of the male fetal phenotype, prompted further cytogenetic and molecular studies. Chromosome marker studies on the parents' blood and chorionic villi confirmed both maternal and paternal inheritance of chromosomes in the CVS. DNA studies on formalin-fixed skin using a Y-specific probe, DYZ1, confirmed the presence of a Y chromosome in the fetus. The most likely cause of the discrepant CVS karyotype is the presence of an undetected degenerating dizygotic twin.     

新千年的能源

本文讨论了有关能源的思想观念的演变.20年前当几位作者开始携手合作研究能源时,人们一般是以发展的眼光、从供应方的角度来考虑能源问题,将注意力集中到消费趋势以及如何扩大供给以满足不断增长的需求上.这种方法在能源利用的环境影响、安全性和公平合理性方面的研究局限深深地困扰着他们.例如,大约有20亿人口经济条件有限,买不起现代能源,这严重限制了他们生活水平的提高.此外,能源还是造成环境问题的重要因素,其中包括室内空气污染、城市空气污染、酸化和全球气候变暧等.笔者认为,应当树立新的能源供给观念,使能源的供给方式有助于解决这些严重问题.笔者主张,能源必须成为推进可持续发展——经济上可行、以需要为导向、自力更生的能及无损于环境的发展——的工具,而且,应当将研究重点放在能源的终端用途上和能源供应的服务上.有助于实现可持续发展目标的能源技术方案也在本文进行了讨论.文中强调了制订和运用新型能源技术解决方案的必要性.笔者以巴西乙醇的利用为例,阐述了使发展中国家避免重复工业化国家所犯错误而在技术上实现跨越式发展的可能性.文中还重点介绍了在发展中国家引进先进技术过程中外国直接投资可能起到的作用,阐述了农村能源的近期和远期战略.最后,介绍了促进能源系统的发展,使之与可持续发展的步调一致并且支持可持续发展的相关政策.     

Interaction effects of insecticides on microbial populations and dehydrogenase activity in a black clay soil

Three insecticides, monocrotophos, quinalphos, and cypermethrin, were applied at 0, 5, 10, and 25 microg g(-1) either singly or in combination to a black clay soil to investigate their effects on the soil microflora and dehydrogenase activity. All three insecticides significantly enhanced the proliferation of bacteria and fungi and the soil dehydrogenase activity even at the highest level of 25 microg g(-1). Monocrotophos or quinalphos in combination with cypermethrin at tested levels interacted significantly to yield additive, synergistic, and antagonistic responses toward bacteria and fungi and dehydrogenase activity in soil. Antagonistic interactions were more pronounced toward soil microflora and dehydrogenase activity when the two (monocrotophos or quinalphos + cypermethrin) insecticides were present together in the soil at highest level (25 + 25 microg g(-1)), whereas synergistic or additive responses occurred at lower level with the same combination of insecticides in soil.     

In vivo effects of trivalent and hexavalent chromium on renal and hepatic atpases of a freshwater teleost Anabas scandens

The in vivo toxic effect of trivalent and hexavalent chromium (25 mg/L) on the renal and hepatic tissue ATPases of an edible teleost Anabas scandens was studied. In an exposure span of 30 days Na⁺-K⁺ ATPase activity exhibited a progressive inhibition in the kidney, but marked inhibition in Na⁺-K⁺ ATPase activity was observed in the liver. Mg²⁺ ATPase activity, however, exhibited an elevation on early exposures, with a later inhibition.     

Methyl farnesoate stimulates testicular growth in the freshwater crab Oziotelphusa senex senex fabricius

 The influence of methyl farnesoate (MF) on testicular growth in the fresh water crab Oziotelplusa senex senex was studied. MF stimulated testicular growth as evidenced by increased testicular weight, testicular index and testicular follicle diameter in MF injected crabs and provides evidence that MF acts as a male reproductive hormone in crustacea. Received: 25 August 1998 / Accepted: 18 February 1999     

Novel extractive colorimetric and UV spectrophotometric estimation of etizolam in bulk and tablet by forming ion association complex with methyl orange and bromocresol green

A novel, sensitive, and rapid UV spectrophotometric and colorimetric method was developed for estimation of etizolam (ETZ) in bulk and tablet. The UV spectrophotometric method (method I) is based on quantitative estimation of ETZ using 0.1N NaOH as the solvent which exhibits maximal absorption at 378 nm. Colorimetric methods (method II and III) were based on the formation of color complex in association with ions between basic nitrogen of the drug with methyl orange (MO) and bromocresol green (BCG) in acidic medium. The formed color complexes were quantitatively extracted with chloroform and measured at 509 nm for Drug–MO complex and at 442 nm for Drug–BCG complex, respectively. Beer's law was obeyed over the linear ranges 2–16 µg/ml (method I), 5–45 µg/ml (method II), and 2–20 µg/ml (method III). The correlation coefficient (r²) for ETZ was 0.999, 0.997, and 0.998 for method I, II, and III, respectively. All methods were successfully applied for the assay of the drug in tablet. The % purity was found to be 98.52 (method I), 98.72 (method II), and 99.18 (method III). These developed methods were fully validated with % relative standard deviation (RSD) for accuracy less than 2 for all methods. The % RSD of the intra-day and inter-day variations was found to be less than 2%. The limit of detection and quantitation were as follows: 0.108 µg/ml and 0.327 µg/ml (method I), 0.24 µg/ml and 0.75 µg/ml (method II), 0.1 µg/ml and 0.5 µg/ml (method III) indicating marked method sensitivity. Empirical evidence from all three methods concludes that developed methods are simple, sensitive, and reliably validated for useful routine quality control analysis of ETZ.     

Multi-component synthesis and antimicrobial activity of novel imidazo[4,5-f] indol-7-yl)indolin-2-ones

A three-component one-pot protocol has been investigated for the synthesis of imidazo[4,5-f]indol-7-yl)indolin-2-ones from the commercially available materials. Structures of these compounds were established on the basis of IR, ¹H NMR, and mass spectral data. The title compounds were evaluated for their antimicrobial activity. Two compounds exhibited the potent antimicrobial activity.