Intervention trial with selenium for the prevention of lung cancer among tin miners in Yunnan,China

This pilot study evaluated the feasibility and effectiveness of conducting a double-blind clinical trial for the prevention of lung cancer with selenium (Se) in Yunnan Tin Corporation, the People's Republic of China, where the incidence rates of lung cancer are extraordinarily high among the miners. Forty healthy miners were randomized to either 300 μg of Se in high Se malt cakes or an identical placebo of malt cakes daily for one year. Subjects consumed their usual daily diet. The low Se concentrations in plasma (0.05±0.008 μg/mL) and hair (0.442±0.085 μg/g) reflected their low dietary Se intake in the control subjects. In Se-supplemented group, the Se status was increased by 178% for serum and 194.8% for hair. The serum GSHpx activity was increased by 155.7%, whereas the lipid peroxide level was reduced by 74.5% compared to the placebo. The results of UDS assay indicated that the lymphocyte DNA damage induced by ultraviolet irradiation and carcinogen 3,4-benzpyrene could be protected by Se supplementation. Se-supplementation did not affect the liver function test (SGPT), as well as the concentrations of hemoglobin, albumin, and cholesterol. Thus, daily intake of 300 μg Se in form of Se-malt as a chemopreventive measure is safe and effective to humans with low Se status.     

小麦与玉米及鸭茅状摩擦禾远缘杂交的胚发育过程中同工酶和蛋白质的变化

通过比较小麦与玉米及鸭茅状摩擦禾属间杂交获得的胚与小麦正常自交的胚之间在不同发育时期过氧化物酶和酯酶的同工酶谱,发现过氧化物酶同工酶表现出时空顺序的特异性变化。在同一发育时期,远缘杂交的具胚子房和无胚子房之间存在过氧化物酶同工酶谱的差异,这可能涉及到与胚发育相关的同工酶的出现。远缘杂交的具胚子房和正常自交的小麦子房之间也有一定的酶谱差异。同时,同一材料还表现出不同发育时期的过氧化物酶酶谱差别。在远缘杂交后的胚发育期间,酯酶同工酶的时空表达不如过氧化物酶显著。此外,对远缘杂交后的胚中的水溶性蛋白质进行了SD S-PAGE分析,初步的分析结果表明,可能存在与胚发育相关的蛋白质。     

简便、快速提取高质量的RNA分子

MethodsforHandy,RapidIsolationofHighQualityRNAbyGuanadiumThioeyauateDuJianYuanYanhuaMaShenglinDongZhiwei(BeijingInstituteforCancerResearchBeijing100034)硫氰胍是一种有效的蛋白变性剂。早在1979年,Chirgwin等就利用氯化铯／硫氰胍超离心技术成功地从RNA酶富集的胰脏组织中提取出未降解的RNA分子[2],从而使它成为抑制RNA酶的首选药物并得到广泛使用,但受到超速离心设备的限制。1983年,Cathala报道了氯化锂／硫氰胍RNA提取法[1]。该方法操作简便,获得的RNA质量很高,但所需时间较长。为了能在短时间内更快…     

罂粟科植物的分类,进化与分布

罂粟科有38属约700种,作者通过对科内各属的研究,根据其主要器官(雌蕊、雄蕊,花被、果和种子)的进化趋势,重新排列科内的分类系统,在3个亚科下,包括8个亚族。在此基础上,讨论各属可能的演化关系,分析它们的分布规律,最后探讨本科的起源。     

Coordinated mRNA and Protein Expression of Human LAMP-1 in Induction of Melanogenesis After UV-B Exposure and Co-Transfection of Human Tyrosinase and TRP-1 cDNAs

In order to better understand the cascade of melanogenic events in melanocytes, this report has introduced our two recent approaches for the expression of melanogenesis/or melanosome-associated genes and encoded proteins in melanocytes (melanoma cells) after repeated exposure to UV -B and after cotransfection of two human genes, i.e., tyrosinase and tyrosinase-related protein-1 (TRP-1). Repeated exposure of UV B (2.5–5.0 mJ/cm²) caused not only upregulation of tyrosinase and TRP-1 genes but also coordinated increase in the gene and protein synthesis expression of Lamp-1 (lysosome-associated membrane protein-1). When COS-7 kidney cells and amelanotic melanoma (C32 and SKMEL-24) and melanotic melanoma (G361 and SK-MEL-23) cells were exposed to cotransfection of human tyrosinase and TRP-1 cDNAs, there was also an increased expression of Lamp-1 mRNA and protein along with tyrosinase activation and new melanin synthesis. Importantly, single transfectants of human tyrosinase cDNA revealed marked cellular degeneration, whereas this degeneration was not seen in single transfectants of TRP-1 cDNA or cotransfectants of human tyrosinase and TRP-1 cDNAs, indicating that TRP-1 prevented, along with Lamp-1, programmed death of melanocytes after transfection of tyrosinase gene. The coordinated expression of TRP-1 and Lamp-1 was further confirmed by antisense oligodeoxynucleotide hybridization experiment against Lamp-1 gene, showing the decreased expression of TRP-1 as identified by three different types of anti-TRP-1 monoclonal antibodies. We propose therefore that human tyrosinase and TRP-l, when activated or expressed together, will coordinate to upregulate the mRNA expression and protein synthesis of Lamp-1. The Lamp-1 molecules will, in turn, cover the inner surface of melanosomal membrane, together with TRP-1 molecules, thus protecting the melanosomal membrane from toxic melanin intermediates generated during melanogenesis in the presence of active tyrosinase. In contrast, the expression of other lysosome-related proteins, e.g., β-galactosidase and CD63 is not stimulated in new melanogenesis.     

广义捕食系统无闭轨的几组充分条件

本文对一类广义捕食系统生物种群生态常微模型建立几组无闭轨的充分条件,为开拓涉及该类模型制作参考类作全局制图定性的研究．     

6个猕猴桃品种的果实贮藏与品质评价

为了选育耐贮藏且风味品质优异的猕猴桃(Actinidia)新品种,对美味猕猴桃(A.deliciosa)的3个野生品种‘kvf54’、‘kvf6’、‘鑫美’和3个栽培种‘秦美’、‘华美’、‘徐香’的品质和贮藏特性等进行比较分析。结果表明,常温和1℃贮藏下‘kvf54’和‘徐香’的硬度下降趋势相近,优于其他品种,且‘kvf54’的维生素C (V_C)含量最高。而在相同贮藏条件下,‘鑫美’可溶性固形物含量积累速度最快,淀粉和可滴定酸含量最少,贮藏性能不佳。‘kvf54’相比于其他品种的贮藏性更好,V_C、糖类物质等含量高,是可用于培育耐贮藏新品种的优质材料。     

钾通道阻断剂所致的蜗内直流电位改变

本实验采用耳蜗外淋巴灌流技术,观察了四氨基吡啶(4-AP)、四乙基铵(TEA)以及奎宁等不同钾通道阻断剂对豚鼠蜗内直流电位(EP)的影响。发现快钾通道阻断剂4-AP对EP无明显影响,但可改变强噪声所致EP改变的形式。TEA与奎宁则可减少负相EP(N-EP)的绝对值。实验结果提示耳蜗内有不同类型的钾离子通道存在并各具有不同的生理意义。