肠道真菌研究进展

真菌菌群是肠道菌群的重要组成部分,在肠道微生态稳态的维持和宿主的免疫调节中发挥重要作用。肠道真菌失调通常和肠道疾病甚至肠道外疾病有关。本文就肠道真菌的定殖与组成、真菌菌群对肠道微生态的调控、菌群失调促进疾病的发展机制、基于肠道真菌的治疗策略和肠道真菌的鉴定分析方法等方面的进展进行了综述和展望,旨在系统认识肠道真菌调节宿主健康和促进疾病发生的机制,为相关疾病的诊断和治疗提供重要参考。     

EVALUATION OF EXTRACTS FROM BAMBOO FOR BIOLOGICAL ACTIVITY AGAINST CULEX PIPIENS PALLENS

Abstract The extracts from 7 species of bamboo were tested for larvicidal activity against Culex pipiens pallens . At the tested concentration, the extracts of selected bamboo had different degree of toxic effects on the fourth instar larvae of Culex pipiens pallens . Among them, the extracts of Pleioblastus juxianensis, Brachystachyum albostriatum, Phyllostachys platyglossa and Pleioblastus amarus were found to be effective with LC₅₀values at 24 h of 30.65 mg/L, 53.94 mg/L, 41.21 mg/L and 54.49 mg/L respectively, against Culex pipiens pallens larvae. The extract of Pleioblastus juxianensis by Soxhlet method showed stronger activity than the extract obtained by interval-shaking, the LC₅₀ of which were 30.65 mg/L and 48.34 mg/L, respectively. The diethyl ether extract of Pleioblastus juxianensis exhibited better larvicidal activity than the methanol extract and the petroleum ether extract. The results would help to provide the basis for the study of environment acceptable pesticide for mosquito control, and also help to comprehensively utilize the source of bamboo.     

Repair effect of thymine radical anion by echinocoside using pulse radiolysis

Repair activities of thymine radical anion by echinocoside, isolated from Pedicularis plicata. were studied using pulse radiolysis technique. The thymine radical anion was produced by the reaction of hydrated electron with thymine. Echinocoside. one of the polyphenols of phenylpropanoid glycoside, was added to the thymine aqueous solution saturated with N2. Kinetic analysis by transient absorption spectrum showed that thymine radical anion was formed at first, and then after several decades of microseconds of pulse radiolysis. the spectrum of thymine radical anion was changed to that of echinocoside radical anion. The evidence indicated that thymine radical anion was repaired through one-electron-transfer between the DNA base radical anion and echinocoside. The rate constant of electron transfer by echinocoside was 1.45× 109 dm3 · mol1 · s 1.     

大鼠不同脑区突触体钙水平的年龄差异

本实验使用荧光指示剂Ｆｕｒａ－２与Ｔｂ~（３＋）,检测了不同年龄组大鼠的不同脑区（海马、皮层、间脑、小脑）突触体内游离钙与膜结合钙水平。结果显示,与青年对照组相比,老年大鼠大部分脑区（海马、皮层、间脑）突触体内游离钙水平显著增高,尤其是海马突触体内游离钙增高极为显著;其突触体膜结合钙水平表现为：海马、小脑两脑区明显升高,而皮层、间脑两脑区明显下降,呈现一种全脑范围内的钙水平失衡。提示动物的衰老与其脑内钙自体平衡失调有关。     

Mechanisms of the actions of aromatase inhibitors 4-hydroxyandrostenedione, fadrozole, and aminoglutethimide on aromatase in JEG-3 cell culture

Selective inhibition of estrogen production with aromatase inhibitors has been found to be an effective strategy for breast cancer treatment. Most studies have focused on inhibitor screening and in vitro kinetic analysis of aromatase inhibition using placental microsomes. In order to determine the effects of different inhibitors on aromatase in the whole cell, we have utilized the human choriocarcinoma cell line, JEG-3 in culture to compare and study three classes of aromatase inhibitors, 4-hydroxyandrostenedione, fadrozole (CGS 16949A), and aminoglutethimide. Fadrozole is the most potent competitive inhibitor and aminoglutethimide is the least potent among the three. However, stimulation of aromatase activity was found to occur when JEG-3 cells were preincubated with aminoglutethimide. In contrast, 4-OHA and fadrozole caused sustained inhibition of aromatase activity in both JEG-3 cells and placental microsomes, which was not reversed even after the removal of the inhibitors. 4-OHA bound irreversibly to the active site of aromatase and caused inactivation of the enzyme which followed pseudo-first order kinetics. However, 4-OHA appears to be metabolized rapidly in JEG-3 cells. Sustained inhibition of aromatase induced by fadrozole occurs by a different mechanism. Although fadrozole bound tightly to aromatase at a site distinct from the steroid binding site, the inhibition of aromatase activity by fadrozole does not involve a reactive process. None of the inhibitors stimulated aromatase mRNA synthesis in JEG-3 cells during 8 h treatment. The stimulation of aromatase activity by AG appeared to be due to stabilization of aromatase protein. According to these results, 4-OHA and fadrozole would be expected to be more beneficial in the treatment of breast cancer patients than AG. The increase in aromatase activity by AG may counteract its therapeutic effect and might be partially responsible for relapse of breast cancer patients from this treatment.