关于关联BCK-代数

本文建立了有限初始段关联BCK-代数与无限初始段关联BCK-代数的概念。获得三个主要结果:任一有限初始段关联BCK-代数与的某一子代数同构;对任一关联BCK-代数,规定X_0={x|x∈X,A(x)是有限集},则X_0是X的理想;当X_0是有限集且X_0≠X时,商代数X/X_0是无限初始段关联BCK-代数。     

A naturally immunogenic virion-associated protein specific for HIV-2 and SIV

The genomic organization of HIV-1 and the family of HIV-2 and SIV viruses is similar. However, there is an open reading frame, orf-x, that is present in HIV-2 and SIV, but not in HIV-1. The extent of protein sequence conservation in orf-x between HIV-2ROD and SIVMAC suggests that this open reading frame encodes a gene that may be important for infectivity or replication. Here, we show that the orf-x products of SIVMAC and HIV-2SBL-6669 are virion-associated and that the introduction of a premature stop codon into orf-x, did not abrogate virus infectivity and replication in vitro. Antibody reactivity to the orf-x product was detected in 35 of 42 HIV-2 positive serum samples and 11 of 52 SIV seropositive monkeys. No such antibodies were detected in HIV-1 positive donors, blood donors seronegative for both HIV-2 and HIV-1, or SIV seronegative monkeys. This suggests that orf-x is dispensable for in vitro replication of SIVMAC and that the orf-x gene product of HIV-2 or its antibody can be used to distinguish HIV-2 from HIV-1 infection.     

Synphilin-1 associates with alpha-synuclein and promotes the formation of cytosolic inclusions.

Parkinson disease (PD) is a neurodegenerative disease characterized by tremor, bradykinesia, rigidity and postural instability. Post-mortem examination shows loss of neurons and Lewy bodies, which are cytoplasmic eosinophilic inclusions, in the substantia nigra and other brain regions. A few families have PD caused by mutations (A53T or A30P) in the gene SNCA (encoding alpha-synuclein). Alpha-synuclein is present in Lewy bodies of patients with sporadic PD, suggesting that alpha-synuclein may be involved in the pathogenesis of PD. It is unknown how alpha-synuclein contributes to the cellular and biochemical mechanisms of PD, and its normal functions and biochemical properties are poorly understood. To determine the protein-interaction partners of alpha-synuclein, we performed a yeast two-hybrid screen. We identified a novel interacting protein, which we term synphilin-1 (encoded by the gene SNCAIP). We found that alpha-synuclein interacts in vivo with synphilin-1 in neurons. Co-transfection of both proteins (but not control proteins) in HEK 293 cells yields cytoplasmic eosinophilic inclusions.     

In vivo incorporation of14C-phenylalanine into ascidian tunichrome

Ascidia ceratodes exposed to¹⁴C-phenylalanine in the surrounding seawater incorporates the radiolabel into newly biosynthesized tunichrome molecules. Radioactivity can be detected in tunichrome extracted from circulating blood cells within one day following initial exposure to the radiolabel; weak activity (4 Ci/mol tunichrome=22 nmol phenylalanine/mol tunichrome) is detected in 1 to 10 days; significantly higher amounts of radiolabel (57 Ci/mol tunichrome=318 nmol phenylalanine/mol tunichrome) appear 20 days after seawater exposure. Therefore, phenylalanine can function as a precursor in the biosynthesis of tunichrome.     

A negative inotropic effect of acetylcholine in the presence of several phosphodiesterase inhibitors

Summary The phosphodiesterase inhibitors papaverine, theophylline and 3-isobutyl-1-methylxanthine (IBMX) reveal a negative inotropic effect of acetylcholine in cat ventricular heart muscle. This effect is unrelated to -adrenoceptor stimulation and possibly mediated by the accumulation of cyclic GMP.I thank Mrs Petra Lauck for help. This work was supported by the Deutsche Forschungsgemeinschaft.     

浅谈企业人力资本的三大激励机制

在经济全球化、市场竞争日趋激烈的今天，为提升企业的综合竞争力，众多企业面临的一个很重要的问题就是如何留用人才，用好人才，为人才的成长创造宽松的空间和环境。从企业人力资源管理入手，重点从3个方面阐述了建立激励机制的原因及途径。     

Pycnogenol enhances immune and haemopoietic functions in senescence-accelerated mice

Pycnogenol (procyanidin extracted from Pinus maritima) has been shown to be a potent free radical scavenger and an antioxidant phytochemical. The effects of pycnogenol on immune and haemopoietic dysfunction in senescence-accelerated mice (SAM), as a murine model of accelerated ageing, were determined. SAMP8, a strain of senile-prone mice, exhibit learning and memory deficits, immunodeficiency and dysfunction of the haemopoietic system. Oral feeding with pycnogenol for 2 months significantly improved their T- and B-cell function. Pycnogenol also augmented the proliferative capacity of haemopoietic progenitors of bone marrow in SAMP8. These data suggest that pycnogenol may be useful for either retardation or restoration of parameters associated with ageing. Received 3 July 1998; accepted 28 July 1998     

雪莲中水溶性多糖提取及纯化的工艺优化

目的对比不同温度、液料比以及提取时间等条件对于雪莲组织中水溶性多糖提取率的影响,研究从雪莲组织中提取水溶性多糖的最佳工艺,并对提取的粗多糖进行脱蛋白纯化．方法以产自新疆昭苏天山雪莲为材料,以多糖的得率为评价指标,采用正交试验方法,探讨不同条件下对雪莲组织中水溶性多糖提取起到明显作用的因素,采用Sevage法结合酶法对提取的粗多糖进行纯化．结果在浸提时间为2．5h、温度80℃、液料比例为14mL：1g的条件下,提取粗多糖得率最高为6．91％,该粗多糖中总糖的质量分数为18．47％,该条件为提取的最佳工艺条件．对粗多糖进行纯化,除去其中蛋白质,回收率为71．4％．结论本次实验确定了雪莲组织中水溶性多糖提取的最佳工艺条件,经过进一步的脱蛋白纯化处理,为实验室下一步的组分分离以及探讨雪莲多糖的药理作用奠定了基础．     

微乳液介质中5''-硝基水杨基荧光酮光度法测定钼

研究了在阳离子型微乳液(CTMAB-正丁醇-环己烷-水)介质中,钼()-5’-硝基水杨基荧光酮(5'-NSF)的显色反应。结果表明,在0.24~0.60 mol.L-1HCl溶液中,钼与5'-NSF形成1∶2的橙红色稳定络合物,其最大吸收波长为529 nm,Δλ=60 nm,表观摩尔吸光系数ε529=6.55×105mol-1.cm-1,钼的浓度在0~0.20 mg/L范围内符合比尔定律。此方法灵敏度高,用于样品中微量钼的测定,结果令人满意。