The role of glutathione in dopaminergic neuronal survival

An increased production of reactive oxygen species is thought to be critical to the pathogenesis of Parkinson's disease. At autopsy, patients with either presymptomatic or symptomatic Parkinson's disease have a decreased level of glutathione in the substantia nigra pars compacta. This change represents the earliest index of oxidative stress in Parkinson's disease discovered to this point. This study compares the sensitivity of dopaminergic and nondopaminergic neurons in dissociated mesencephalic cultures to the depletion of glutathione. We have found that dopaminergic neurons are more resistant to the toxicity of glutathione depletion than nondopaminergic neurons. The possibility that dopaminergic neurons have a higher baseline glutathione level than nondopaminergic neurons is suggested by measurements of levels of cellular glutathione in a parallel system of immortalized embryonic dopaminergic and nondopaminergic cell lines. We also examined the role of glutathione in 1-methyl-4-phenylpyridinium toxicity. Decreasing the glutathione level of dopaminergic neurons potentiates their susceptibility to 1-methyl-4-phenylpyridinium toxicity, although 1-methyl-4-phenylpyridinium does not deplete glutathione from primary mesencephalic cultures. Our data suggest that although a decreased glutathione content is not likely to be the sole cause of dopaminergic neuronal loss in Parkinson's disease, decreased glutathione content may act in conjunction with other factors such as 1-methyl-4-phenylpyridinium to cause the selective death of dopaminergic neurons.     

浅谈托辊的开发与实践

本钢１７００连轧机应用的托辊原由外企业制作，为了减少公司资金外流，公司技术人员和工人结合现有的生产条件，先后攻克了辊身铸造和加工，托辊装配等工艺方面的难关，研制成功了合格的产品，年创经济效益８０万元。     

Digital Connectivity and Extended Well-Composed Sets for Gray Images

In this paper, we propose a new definition of digital connectivity for gray images on a 2D space for arbitrary grid systems. We extend a digital version of the Jordan curve theorem and its converse proved earlier by Rosenfeld for the rectangular grid system. We also extend in two directions the concept of well-composed sets introduced by Lateckiet al.(1995,Comput. Vision Image Understanding61,70–83). First, we extend the definition of well-composed sets from the quadratic grid system to an arbitrary grid system. Then, by using the concept of parameter-dependent connected components introduced by us in a previous work, we allow the pixels in a connected component of a well-composed set to have different gray values so that the connectivity of connected components accommodates a wider meaning.     

Isolation of a genetic locus associated with metronidazole resistance in Helicobacter pylori

We examined the molecular mechanism of metronidazole resistance by constructing a lambda-Zap II phagemid expression library with genomic DNA from a metronidazole-resistance strain of Helicobacter pylori. Twenty-two clones were found to have elevated MTZ resistances in XLOLR strain of E. coli. Phagemids belonging to the twenty two clones were extracted and then retransformed into the XLOLR strain of E. coli. After MTZ selection, five clones could confer metronidazole resistance consistently. According to Southern hybridization and DNA sequencing, the five clones contained a same locus, recA. In addition, transforming the five clones into BL21 strain of E. coli produced a higher resistance to MTZ. Interestingly, electroporation of one of the five phagemid clones into two MTZ sensitive H. pylori yielded MTZ resistant strains. Comparing amino acid sequence in MTZ resistant with sensitive isolates revealed two point mutations at this locus. Above results suggest that mutation in recA may be associated with metronidazole resistance of H. pylori.     

Prognostic factors of early sequelae and fatal outcome of Japanese encephalitis

A clinical case control study to identify prognostic factors present at hospital admission associated with early sequelae and fatal outcome of acute Japanese encephalitis (JE) was carried out in Gusi county, Henan Province, central China from June to September 1991. A total of 70 patients with laboratory-confirmed acute JE were studied, of whom 3 cases died and 33 cases had neurological or psychiatric sequelae at the end of three months follow-up. The results showed that acute JE at younger age, with higher body temperature, high white cell count in CSF, and deep coma present at hospital admission were markers for unfavorable outcomes (sequelae or fatal). A history of the vaccination was not correlated with the early sequelae and fatal outcome of the disease. The paper suggests that early diagnosis and treatment and universal JE vaccination for all susceptible populations are keys for decreasing incidence of sequelae and fatal outcome of acute JE.     

冶金炉渣氮化物容量研究的进展

本文总结了近年冶金炉渣氮酸盐容量的研究方法，氮在炉渣中存在形态与炉渣氧分压的关系，炉渣氮化物容量与温度及炉渣成分的关系，并给出设计钢液脱氮渣系的基本原则。     

不同工作制曲柄连杆式飞剪机的设计

通过对曲柄连杆式飞剪机工作制和工作特点的分析,介绍了不同工作制飞剪机的设计要点,给出了在设计中应遵循的原则,从而使其设计更加合理.     

中国公用电话业务发展值得借鉴的几个案例

随着技术和需求的不断发展,电信市场逐步走向开放,竞争更加激烈。如何抓住信息技术革命的新契机,充分掌握公话的发展方向,成为电信运营商和设备供应商的首要课题。从不同国家的公话案例得到的重要启示是:①无论是发达国家还是发展中国家,归根结底都是市场需求决定了公话的发展趋势;②作为一个运营商,首先要考虑如何优化运营成本,避免重复建设,降低总投资,缩短项目周期,同时还要引进和利用世界上最先进的技术,突破传统语音电路交换网络的限制,利用多种接入方式开展业务;③从全球来看,通信业务将从传统的话音业务逐渐向数据业务发展,运营商可以利用数字通信的优势,为广大公众用户提供个性化数字信息服务