Glutathione system in erythrocytes and blood plasma in strokes and dyscirculatory encephalopathy

Dyscirculatory encephalopathy and mild ischemic stroke are characterized by solitary changes in components of glutathione metabolism. In moderate and severe ischemic strokes essential changes have been found. Changes in glutathione metabolism are also expressed in hemorrhagic stroke. The clearest increase was found in activities of glutathione peroxidase and glutathione transferase and in rare cases in activities of glutathione reductase and GSH concentration. The increase of enzymes activity was not found in patients with delayed onset of treatment (more than 3 days) and also in severe cases terminated by subsequent death of patients. Glutathione system is obviously important for tolerance to cerebral ischemia.     

羊瘙痒因子263K毒株感染金黄地鼠后鼠脑组织中检出PrP-res蛋白及其神经病理学研究

羊瘙痒病是累及山羊及绵羊的可传播海绵状脑病。为了观察羊瘙痒因子 (Scrapie)的病原特征及病理组织改变特点 ,将羊瘙痒因子 2 6 3K毒株颅内接种至金黄地鼠。经过 81～ 110天的潜伏期 ,89%的动物发病 (17/19只 )。对发病地鼠的神经病理学检测发现 ,海绵状空泡变性的检出率为 5 9% ,淀粉样斑的检出率为 17 6 %。利用免疫组化和蛋白酶消化后的Westernblotting检测证实 ,10 0 %的发病地鼠的脑组织中都出现蛋白酶抗性朊蛋白 (PrP res)。17只发病地鼠脑组织提取物中 ,PrP res的泳动位置和分子量大小完全一致 ,出现两条分子量在 2 5kD～ 31kD的反应带。尝试应用快速玻片印迹法检测病变组织中的PrP res,结果显示 ,与常规固定包埋切片的免疫组化检出效果相似。这提示脑组织印片法可成为临床检测克 雅氏病 (Creutzfeldt Jacobdisease ,CJD)患者脑组织活检标本中PrP res的快速、有效的方法。羊瘙痒因子 2 6 3K成功感染金黄地鼠再次证明 ,金黄地鼠是TSE感染因子良好的动物模型 ,发病率高 ,潜伏期短 ,发病动物PrP res的检出率明显高于典型病理改变的检出率。新生成的PrP res的电泳类型与接种的TSE因子有关 ,与宿主的个体差异无关 ,提示TSE感染因子的确存在“株”的现象。     

Scrapie prion protein structural constraints obtained by limited proteolysis and mass spectrometry

Elucidation of the structure of scrapie prion protein (PrP^Sc), essential to understand the molecular mechanism of prion transmission, continues to be one of the major challenges in prion research and is hampered by the insolubility and polymeric character of PrP^Sc. Limited proteolysis is a useful tool to obtain insight on structural features of proteins: proteolytic enzymes cleave proteins more readily at exposed sites, preferentially within loops, and rarely in β-strands. We treated PrP^Sc isolated from brains of hamsters infected with 263K and drowsy prions with varying concentrations of proteinase K (PK). After PK deactivation, PrP^Sc was denatured, reduced, and cleaved at Cys179 with 2-nitro-5-thiocyanatobenzoic acid. Fragments were analyzed by nano-HPLC/mass spectrometry and matrix-assisted laser desorption/ionization. Besides the known cleavages at positions 90, 86, and 92 for 263K prions and at positions 86, 90, 92, 98, and 101 for drowsy prions, our data clearly demonstrate the existence of additional cleavage sites at more internal positions, including 117, 119, 135, 139, 142, and 154 in both strains. PK concentration dependence analysis and limited proteolysis after partial unfolding of PrP^Sc confirmed that only the mentioned cleavage sites at the N-terminal side of the PrP^Sc are susceptible to PK. Our results indicate that besides the “classic” amino-terminal PK cleavage points, PrP^Sc contains, in its middle core, regions that show some degree of susceptibility to proteases and must therefore correspond to subdomains with some degree of structural flexibility, interspersed with stretches of amino acids of high resistance to proteases. These results are compatible with a structure consisting of short β-sheet stretches connected by loops and turns.     

A structural basis for loop C-sheet polymerization in serpins

In this study, we report the X-ray crystal structure of an N-terminally truncated variant of the bacterial serpin, tengpin (tengpinΔ42). Our data reveal that tengpinΔ42 adopts a variation of the latent conformation in which the reactive center loop is hyperinserted into the A β-sheet and removed from the vicinity of the C-sheet. This conformational change leaves the C β-sheet completely exposed and permits antiparallel edge-strand interactions between the exposed portion of the reactive center loop of one molecule and strand s2C of the C β-sheet of the neighboring molecule in the crystal lattice. Our structural data thus reveal that tengpinΔ42 forms a loop C-sheet polymer in the crystal lattice. In vivo serpins have a propensity to misfold and form long-chain polymers, a process that underlies serpinopathies such as emphysema, thrombosis and dementia. Native serpins are thought to polymerize via a loop A-sheet mechanism. However, studies on plasminogen activator inhibitor 1 and the S49P variant of human neuroserpin reveal that the latent form of these molecules can also polymerize. Polymerization of latent neuroserpin may be important for the development of familial encephalopathy with neuroserpin inclusion bodies. Our structural data provide a possible mechanism for polymerization by latent serpins.     

Review. The epidemiology of kuru: monitoring the epidemic from its peak to its end

Kuru is a fatal transmissible spongiform encephalopathy restricted to the Fore people and their neighbours in a remote region of the Eastern Highlands of Papua New Guinea. When first investigated in 1957 it was found to be present in epidemic proportions, with approximately 1000 deaths in the first 5 years, 1957-1961. The changing epidemiological patterns and other significant findings such as the transmissibility of kuru are described in their historical progression. Monitoring the progress of the epidemic has been carried out by epidemiological surveillance in the field for 50 years. From its peak, the number of deaths from kuru declined to 2 in the last 5 years, indicating that the epidemic is approaching its end. The mode of transmission of the prion agent of kuru was the local mortuary practice of transumption. The prohibition of this practice in the 1950s led to the decline in the epidemic, which has been prolonged into the present century by incubation periods that may exceed 50 years. Currently, the epidemiological surveillance is being maintained and further studies on human genetics and the past mortuary practices are being conducted in the kuru-affected region and in communities beyond it.     

Review. The origin of the prion agent of kuru: molecular and biological strain typing

Kuru is an acquired human prion disease that primarily affected the Fore linguistic group of the Eastern Highlands of Papua New Guinea. The central clinical feature of kuru is progressive cerebellar ataxia and, in sharp contrast to most cases of sporadic Creutzfeldt-Jakob disease (CJD), dementia is a less prominent and usually late clinical feature. In this regard, kuru is more similar to variant CJD, which also has similar prodromal symptoms of sensory disturbance and joint pains in the legs and psychiatric and behavioural changes. Since a significant part of the clinicopathological diversity seen in human prion disease is likely to relate to the propagation of distinct human prion strains, we have compared the transmission properties of kuru prions with those isolated from patients with sporadic, iatrogenic and variant CJD in both transgenic and wild-type mice. These data have established that kuru prions have prion strain properties equivalent to those of classical (sporadic and iatrogenic) CJD prions but distinct from variant CJD prions. Here, we review these findings and discuss how peripheral routes of infection and other factors may be critical modifiers of the kuru phenotype.     

Polymorphisms of Two Indels at the PRNP Gene in Three Beef Cattle Herds

Bovine spongiform encephalopathy (BSE) is a transmissible fatal neurodegenerative disorder, presenting a characteristic spongiform degeneration of cattle brain due to the accumulation of a pathogenic and protease-resistant infectious protein (prion). Two deletion/insertion polymorphisms of the prion protein gene (23 bp at the promoter region and 12 bp at intron 1) were analyzed in three beef cattle herds (Aberdeen Angus, Charolais, and Franqueiro) to verify allele frequencies for possible use in selection of resistant animals. High frequencies of susceptibility alleles (23 and 12 bp deletion) and haplotype (23 del/12 del) were observed in the Aberdeen Angus and Charolais herds, but Franqueiro presented one of the highest frequencies of resistant alleles so far described. These data indicate the need for selection in Aberdeen Angus and Charolais breeds to increase the frequency of resistant animals in order to reduce the probabilities of BSE outbreaks in these populations.     

Transmissible spongiform encephalopathies and tissue cell culture

The discovery of prion proteins and the diseases which are associated with them still present scientists and clinicians with a number of problems. There are clearly risks with the use of living cells and materials of animal origin to produce therapeutic compounds with respect to the transmission of prion protein. However the medical benefit many of these compounds has to be weighed against this. It is clear a number of groups are continuing to unravel the highly complex relationships of prion biology and pathology and it is only when this is clearly established that the community can decide on these issues. Until this time the scientific community must rely on the best research available and provide guidance from this. This revised version was published online in August 2006 with corrections to the Cover Date.     

分子吸附再循环系统治疗肝功能衰竭合并肝性脑病的临床效果观察

目的探讨分子吸附再循环系统在肝功能衰竭合并肝性脑病治疗中的临床应用效果。方法将我院2015年1月~2016年1月收治的肝功能衰竭合并肝性脑病患者100例,根据治疗方式的不同分为观察组和对照组,每组50例。对照组50例患者接受保肝、维持水电解质平衡以及营养支持等综合治疗,观察组50例患者在综合治疗基础之上接受分子吸附再循环系统治疗,并对两组患者的治疗效果,治疗前后肝功能改善情况、不良反应进行统计分析。结果两组患者治疗前的总胆红素、凝血酶原活动度、血氨以及Glasgow昏迷评分比较差异无统计学意义(P0.05)。观察组患者治疗3天后的总胆红素以及血氨明显低于对照组,两组比较差异有统计学意义(P0.05);而且治疗有效率明显高于对照组(P0.05),治疗后肝性脑病清醒率高于对照组(P0.05)。两组患者治疗期间均无严重不良反应。结论肝功能衰竭合并肝性脑病患者在综合治疗上采取分子吸附再循环系统治疗的效果显著,可明显改善患者肝功能,提高肝性脑病清醒率,且不良反应少,值得临床推广使用。