Recent progress in clinical aspects of receptor research

Clinical receptology encompasses broad areas, including receptor or postreceptor defects due to mutations of receptor or other genes, abnormalities due to receptor antibodies and secondary changes of receptors under various pathological conditions. Recent progress in molecular biology has succeeded in cloning genes of receptors, G-proteins and other cellular proteins that are involved in the signal transduction and clarified their germ-line and somatic mutations. It is of importance that mutations of receptors and G-proteins do not necessarily cause loss of function but sometimes cause gain of function of receptors or G-proteins, thus leading to hyperfunction. Molecular basis that causes either loss or gain of function has been studied but is not completely understood. Some examples of gain of function mutatious of G-protein coupled receptors, tyrosin kinase-type receptors and G alpha protein are shown. Another important aspect in receptor research is that mutation of a single receptor gene sometimes result in different phenotypes and even different modes of inheritance. For example, mutations of rhodopsin (a G-protein coupled receptor) gene cause retinitis pigmentosa of autosomal dominant type and autosomal recessive type and also cause congenital stationary night blindness. Exact mechanisms responsible for such differences are not completely understood. There are polymorphisms in some genes that may be involved in some diseases. An example is a polymorphism in beta 3-adrenergic receptor that is claimed but not clearly demonstrated to be a cause of obesity or type II diabetes. Such polymorphism is possibly a gene in polygenic diseases. Receptology is important for elucidating pathogenesis of complex diseases.     

稀土永磁材料研究新进展

综述了稀土永磁材料研究的新进展，重点介绍了具有磁交换耦合作用的新型纳米复合永磁体。通过列举一些典型永磁体合金和其磁性能，讨论了不同合金成分、制备工艺以及添加微量元素对磁性材料微观结构和磁性能的影响。同时说明了在纳米复合永磁材料中硬磁相与软磁相间的磁交换耦合作用机理，以及交换耦合作用对纳米复合永磁材料磁性能的影响。     

我国穿甲弹用钨合金研究的最新进展与展望

综合介绍了我国近年来对穿甲弹用高密度钨合金实施添加微量元素合金化强化和旋转锻造、扭转变形、静液挤压等形变强化的研究进展，以及对于绝热剪切机理和数值模拟计算的研究现状，并介绍了机械合金化制备纳米钨合金复合粉末、温压成形及预氧化活化烧结等特种制备技术方面的最新试验研究进展。通过全面分析目前我国穿甲弹用高密度钨合金试验研究中存在的一些主要问题，提出我国穿甲弹用高密度钨合金今后研制的主攻方向，以及促进高性能穿甲弹用钨合金研制应采取的策略与措施。     

Oxidation of the flavonol fisetin by polyphenol oxidase

The rapid development of endothelin-receptor antagonists has made the endothelin pathway a new therapeutic target in the treatment of cardiovascular diseases, only ten years after the report of its discovery. While the first clinical trials will help to position this new family of compounds in our therapeutic armament for the treatment of essential or secondary forms of hypertension, several preclinical chronic studies already provide a picture of what we can expect from these drugs. Endothelin-receptor antagonists are not effective in all experimental models of hypertension, but those that respond present hypertrophy of small arteries, secondary to a local overexpression of the peptide. Although angiotensin II seems to represent a stimulus for endothelin overexpression in some models, other, as yet undetermined, stimuli are likely in others. Besides their narrow spectrum of antihypertensive activity, endothelin-receptor antagonists may also protect from complications of hypertension by improving end-organ function in a pressure-independent manner. This seems to be the case for the structure and reactivity of resistance arteries, as well as for renal damage. However, it is not clear at this point if cardiac structure and function are improved beyond the benefits produced by blood pressure reduction. The first results in essential hypertensive subjects suggest some degree of efficacy of endothelin-receptor antagonists. Other clinical trials will help to determine if secondary forms of the disease benefit equally or more from this new class of drugs, and if end-organ damage can be reduced beyond blood-pressure reduction.     

Unfolding and refolding of active apple polyphenol oxidase

For the first time, unfolding (6 M guanidine) and refolding of partially proteolysed purified polyphenol oxidase (PPOr) was achieved, with 88% of activity recovered. Optimal refolding conditions consisted in stepwise dialysis of guanidine treated extracts, the dialysis buffers containing 1 M (NH4)2SO4 and 100 microM CuSO4. However, CuSO4 had limited effect on the recovering of PPOr activity, whereas (NH4)2SO4 was essential. Concerning the PPO tertiary structure, denaturing conditions (combinations of boiling and reducing agent) used on SDS-PAGE have shown (i) a compact tertiary structure and (ii) the presence of disulfide bonds in PPOr, accounting for the shift between 27 and 41 kDa, and 41 and 42 kDa, respectively. Resistance to proteolytic cleavage was used to study the conformational changes induced by the denaturing treatments. Folded PPOr was resistant to further proteolysis whereas unfolded PPO was totally digested, indicating the role of tertiary structure of PPOr in the resistance to proteases.     

近年稀土钢研究进展与加速研发新思路

通过对近几年来稀土钢发展相关文献的调研,统计了稀土相关论文、专利增长数量和应用领域分布,分析了稀土钢的研发进展。结果表明,无论是基础研究还是应用领域拓展,稀土钢近年来都得到迅速发展,稀土电工钢和稀土TWIP钢成为最热门的研发钢种,但稀土添加工艺等关键技术的不足,以及有待发展的稀土钢研发方法,延缓了稀土钢的发展与应用。稀土钢生产实践表明各种稀土添加工艺中连铸结晶器喂线法是钢铁连铸生产最有效的稀土添加方法,稀土电渣重熔工艺对生产重大装备制造用大型铸件具有重要应用价值。介绍了有关引入材料基因组工程先进研究理念,发展高通量计算与模拟、高通量制备与表征研究方法,建立稀土钢数据库,加快稀土钢研发的新思路。     

Mg-Zn系耐热铸造镁合金的最新研究进展

综述Mg-Zn系耐热铸造镁合金的最新研究进展,并分析了高温蠕变机理及其设计思路,重点介绍了Cu、Zr、Al及稀土元素RE和碱土元素(Ca、Sr)在Mg-Zn系耐热镁合金中的作用行为,讨论了合金元素使用中存在的问题和今后的发展方向.     

Mg—Zn系耐热铸造镁合金的最新研究进展

综述Mg—Zn系耐热铸造镁合金的最新研究进展,并分析了高温蠕变机理及其设计思路,重点介绍了Cu、Zr、Al及稀土元素RE和碱土元素（Ca、Sr）在Mg—Zn系耐热镁合金中的作用行为,讨论了合金元素使用中存在的问题和今后的发展方向．     

Recent research on calculus

This paper discusses the different types of calcium phosphate in calculus and the role of plaque pH in controlling calcium phosphate precipitation (calculus) or dissolution (caries). There is great site-specificity of deposition of supragingival but not subgingival calculus, with highest amounts of the former being present on the lingual aspects of the mandibular anterior teeth. This may be because the plaque there is most alkaline as that region has the highest salivary film velocity and the lowest salivary sugar concentration during consumption of sugar-containing food and drinks. The importance of calculus removal for good gingival health is emphasised.     

中锰钢塑性失稳现象的研究进展及未来研究展望

中锰钢是近年来出现的新型钢铁材料,因为其优异的力学性能被认为是第三代汽车用钢,但是该钢的一个突出特点就是在拉伸变形时会发生塑性失稳,导致材料结构稳定性减弱甚至在某些情况下过早失效,这已然成为限制中锰钢商业化使用的关键问题。塑性失稳包括出现不连续屈服和屈服平台（吕德斯应变）以及流变应力锯齿（PLC效应）。两者都受到成分、晶粒形貌、退火工艺、组织构成等因素的影响,也均与拉伸变形过程中 奥氏体相变转变存在或强或弱的相关性,使得这一塑性失稳现象的机理更为复杂化,因而在近期各种观点迥异的理论解释也相继被提出。本文综述了相关研究中各种因素对吕德斯应变和PLC效应的影响结果及相关理论解释,并着重指出了各理论解释的局限性及未来的研究思路。最后,基于现有研究和预研实验对在保证中锰钢超高强度和优良塑性的前提下消除中锰钢塑性失稳现象的可行途径进行了展望。      

Inhibitory effects of plant growth regulators on xanthine oxidase

Several plant hormones and analogues were tested for their inhibitory effects on xanthine oxidase. The flavoprotein enzyme, xanthine oxidase, catalyses the oxidation of hypoxanthine to xanthine and then xanthine to uric acid which has lambda max 295 nm. Uric acid was thus the basis for a spectrophotometric assay of the activity of xanthine oxidase. The results showed that trans-zeatin displayed the strongest activity (IC50 = 23.5 muM) on xanthine oxidase inhibition, followed by indole-3-acrylic acid (IC50 = 136.0 muM) and then by the mixed isomers of zeatin (trans-zeatin and cis-zeatin) (IC50 = 198.65 muM). Trans-zeatin induced an uncompetitive inhibition of the enzyme with respect to the substrate xanthine and the apparent inhibition constant (Ki) was 5.09 muM. However, zeatin riboside was inactive. Since xanthine oxidase serum levels are increased in hepatitis, mild hepatic intoxication, tumours brain tissues, and DNA damage induced by cytotoxic agents, it is expected that trans-zeatin may be useful for the treatment of these diseases as well as gout which is caused by deposition of uric acid in the joints and oxidative damage of tissue caused by generation of superoxide anion radical.     

Recent progress of molecular immunology on inflammatory myopathy

The pathogenesis of polymyositis(PM), T-cell-mediated disease, and dermatomyositis(DM), humoral immunity-mediated disease, has not been clearly understood. Retroviruses(HIV, HTLV-I) may play a important role in some PM/DM patients. HTLV-I provirus was detected in infiltrating CD4+ lymphocytes, but not within the muscle fibers by PCR in situ hybridization. It is suggested that HTLV-I-associated PM is not due to direct, persistent infection of the muscle fiber by the virus, but to a T-cell-mediated immunological process triggered by the HTLV-I-infected cells. Inclusion body myositis(IBM) is characterized pathologically by vacuolated muscle fibers containing paired-helical filaments(PHFs) similar to Alzheimer-disease brain. Furthermore, prion protein and mRNA are abnormally accumulated in IBM muscle.