Inhibition of the growth of cariogenic bacteria in vitro by plant falvanones

Phytoalexins, defensive compounds produced by plants against microbial infections, were purified fromSophora exigua (Leguminosae) and their growth inhibitory effects on oral cariogenic bacteria were determined in vitro. Among three isolated compounds, 5,7,2,4-tetrahydroxy-8-lavandulylflavanone completely inhibited the growth of oral bacteria including primary cariogenic mutans streptococci, other oral streptococci, actinomycetes, and lactobacilli, at concentrations of 1.56 to 6.25 g/ml.     

Influence of bistramide A on the twitch tension in rat atrial heart muscle

Bistramide A, a new toxin isolated from the UrochordateLissoclinum bistratum Sluiter, was applied to rat auricular heart muscle bundles. At a stimulation frequency of 0.2 Hz, the toxin induces a dose-dependent reduction of the stimulated twitch tension force; it decreases and shortens the duration of the plateau and the slow repolarizing phase of the action potential. In the control solution, switching from a stimulation frequency of 0.2 Hz to 1 Hz decreases the force with which a positive potentiation develops either at a maintained high frequency or after switching from 1 Hz to 0.2 Hz. Bistramide A reduces both the force evoked at 1 Hz and the potentiation. The data suggest that Bistramide A blocks Na⁺ conductance; inhibits Ca⁺⁺ channels in a time-and frequency-dependent manner; reduces Na⁺–Ca⁺⁺ exchange activity; but does not modify the ability of the sarcoplasmic reticulum to be refilled although the rate of Ca⁺⁺ accumulation is decreased.     

新型食品抗氧剂TBHQ的合成研究

在酸催化下,用对苯二酚和叔丁醇合成了叔丁基对苯二酚（ＴＢＨＱ）,它是一种食用新型抗氧剂。采用正交试验法探讨了各种反应因素对产率的影响。指出在物料比对苯二酚：叔丁醇：催化剂：溶剂为１∶１∶１．２∶２．９（ｍｏｌ）,反应温度为９０℃时,总共反应２．５小时,ＴＢＨＱ得率最高,可达５５％以上。     

用复性电泳技术研究溶酶体蛋白水解酶的性质和活性

介绍了复性单向电泳（Ｇ－ＰＡＧＥ）和复性双向电泳（ＩＥＦ－Ｇ－ＰＡＧＥ）的概念、原理、方法、应用范围、优缺点和使用该方法应注意的事项。并用该方法定性和定量分析了Ｃ６大白鼠神经胶质瘤细胞酸性溶酶体蛋白水解酶的性质和活性。     

牛蒡中多酚氧化酶的活性及其影响因素研究

对牛蒡中所含的多酚氧化酶的活性及其影响因素的研究表明,牛蒡中多酚氧化酶的适宜ｐＨ值是６．０～７．５,适宜温度４５℃,较有效的抑制剂是２％钾明矾和０．０２％ＳＳＡ的混合液,或０．５８％磷酸和０．０２％ＳＳＡ的混合液．用此溶液浸泡过的牛蒡,再用ＨＰＥ薄膜袋包装后,在－４０℃下速冻,放在－１８℃冷冻库保存,贮藏期达６个月以上．     

苯甲酰类化合物构效关系的模式识别研究

用ＣＮＤＯ／２量化方法计算了３５个苯甲酰类化合物的量化指数,并应用模式识别方法研究了该类化合物的结构对治疗患Ｌ１２１０肿瘤小鼠药效的影响,得到满意的分类图。结果表明化合物的抗癌活性的主要影响因素为ＣＱＳ、ＥＬＵＭＯ、ＥＳＨＥＰ和π,药物的抗癌活性主要是通过抑制核苷酸还原酶所致,而且化合物在体内到达受体的过程和难易程度对药效的影响较大。     

RbCl在混合溶剂中的介质效应

应用一价阳离子选择电极和氯离子选择电极组成及逆电池。通过测定电池的电动势,根据溶液热力学原理,引用扩展的Ｄｅｂｙｅ－Ｈｕｅｃｋｅｌ公式,计算求得了ＲｂＣｌ在（Ｈ２Ｏ￣ＤＭＦ）混合溶剂中的活度系数,一级,二级和总介质效应,并对ＲｂＣｌ的介质效应进行了讨论。     

Cloning, construction of prokaryotic expression vector and expression ofEscherichia coli cytosine deaminase gene

Cytosine deaminase gene ofEscherichia coli strain H-30 was cloned, and its initiation codon of ‘GTG’ was mutated to ‘ATG’ by PCR. Prokaryotic recombinant expression vector pBV220-CD was constructed. Clone with high enzyme activity were selected by detecting their specific activity of cytosine deaminase. 5-FC(5-FC, 5-fluorocytosine) could induce the lethal toxicity to cells containing active CD gene. DNA sequence analysis indicated that there were 16 altered bases and 5 of them resulted in the alteration of amino acids in predicted peptide by comparing DNA sequence of the clone H-30-CD-11 with high enzyme activity with CD gene reported in Gene Bank.     

1673K下BaO-BaF_2-Cr_2O_3渣系的热力学性质

１６７３Ｋ下,采用－ＭｏＣｒ＋Ｃｒ２Ｏ３ＺｒＯ２（ＭｇＯ）｛Ｃｕ＋Ｃｒ｝ａｌｏｙ＋（Ｃｒ２Ｏ３）ｓｌａｇＭｏ＋固体电解质电池测定了ＢａＯＢａＦ２Ｃｒ２Ｏ３渣系中Ｃｒ２Ｏ３的活度．研究结果表明,Ｃｒ２Ｏ３的活度随其浓度升高而升高,随ＸＢａＯ／ＸＢａＦ２升高而降低．根据实验及Ｘ射线衍射结果推测了该渣系的等温相图,并作出了该渣系中Ｃｒ２Ｏ３的等活度图．     

土壤酶与土壤肥力关系的研究

论述了各种土壤酶的特性及其相互关系;土壤酶活性与土壤肥力因素之间密切相关;施肥对土壤酶活性有着明显的影响,用酶活性的总体进行土壤肥力水平评价的可能性。