Neuroprotective effect of epigallocatechin‐3‐gallate against N‐methyl‐D‐aspartate‐induced excitotoxicity in the adult rat retina

Purpose: Epigallocatechin‐3‐gallate (EGCG), the major polyphenol of green tea, has been suggested to reduce glutamate excitotoxicity. We therefore investigated the potentially protective effects of EGCG against N‐methyl‐d ‐aspartate (NMDA)‐induced excitotoxicity in the retina. Methods: Female Wistar rats (n = 171) were divided into a normal control group (n = 9); saline control group with intravitreal saline injections (n = 54); NMDA control group with an intravitreal NMDA injection and intraperitoneal saline injections (n = 54); and NMDA study group (n = 54) receiving an intravitreal NMDA injection plus intraperitoneal EGCG (25 mg/kg) injections. Starting at 2 days prior to the intravitreal NMDA injection, the intraperitoneal injections were performed daily for the whole study period. At 12 hr, 1, 2, 3 days, 1 and 2 weeks after the intravitreal NMDA injection, the animals were killed. We counted the neurons in the retinal ganglion cell layer (GCL) on histological sections, measured the thickness of Thy‐1 immunoreactivity and assessed the expression of Thy‐1 mRNA by real‐time polymerase chain reaction. Results: At all time‐points, GCL cell density, thickness of Thy‐1 immunoreactivity and expression of Thy‐1 mRNA were significantly (all p < 0.05) lower in the NMDA control group than in the NMDA study group, in which the parameters were significantly (all p < 0.05) lower than in the saline control group and the normal control group. In both groups with an intravitreal NMDA injection, GCL cell density, thickness of Thy‐1 immunoreactivity and expression of Thy‐1 mRNA decreased significantly with increasing follow‐up time. Conclusions: Intraperitoneal application of EGCG resulted in a significantly less marked NMDA‐associated loss of retinal ganglion cells.     

Epigallocatechin gallate inhibits dimethylhydrazine-induced colorectal cancer in rats

BACKGROUND Epigallocatechin gallate(EGCG) is a polyhydroxy phenolic compound extracted from tea and its antitumor effect has received widespread attention. We explored the inhibitory effect of EGCG on dimethylhydrazine(DMH)-induced colorectal cancer(CRC) using a rat model, predicted the interaction between EGCG and CRC target genes using a database, and explained the EGCG associated target pathways and mechanisms in CRC.AIM To understand the inhibitory mechanisms of EGCG on CRC cell proliferation and identify its pharmacological targets by network pharmacology analysis.METHODS DMH(40 mg/kg, s.c., twice weekly for eight weeks) was used to induce CRC in rats. After model establishment, the rats were administered with EGCG(50, 100,or 200 mg/kg, p.o., once daily for eight weeks) and killed 12 and 20 wk after the start of the experiment. Formation of aberrant crypt foci and tumor was studied by histological analysis. Using network pharmacology analysis, candidate and collective targets of EGCG and CRC were identified, and Gene ontology(GO)and Kyoto Encyclopedia of Genes and Genomes analyses were used to predict the pathways altered by EGCG.RESULTS At week 12, high-dose EGCG treatment significantly reduced the tumor formation rate, total number of tumors, cancerous and non-cancerous tumors,tumor volume, ascites formation, and aberrant crypt foci count. At week 20, all three doses of EGCG were effective. Seventy-eight collective targets of EGCG and CRC were identified, of which 28 genes were dysregulated in CRC. Kyoto Encyclopedia of Genes and Genomes and GO analyses showed that the dysregulated genes were enriched in hsa05210(CRC), hsa04115(p53 signaling pathway), and hsa04151(PI3K-Akt signaling pathway), GO:0043124(negative regulation of I-kappaB kinase/NF-kappaB signaling pathway), GO:0043409(negative regulation of mitogen-activated protein kinase cascade), and GO:2001244(positive regulation of intrinsic apoptotic signaling pathway)respectively.CONCLUSION EGCG inhibits the formation of DMH-induced CRC by regulating key pathways involved in tumorigenesis.     

The osmium-ethyl gallate procedure is superior to silver impregnations for mapping neuronal pathways

Ganglia processed through the osmium-ethyl gallate procedure (OEG)19 retain more structural integrity than those processed through various silver impregnation methods. However, the OEG method continues to be neglected by most neuroanatomists. Both types of procedures have been used to trace large neuronal tracts, but during silver impregnation the neuropils lose many of their identifying characteristics. We demonstrate here the advantages of the OEG procedure by comparing it with two silver techniques, Rowell's and Holmes's. The OEG method yields consistent and reliable results and is easier to carry out than silver protocols. Most importantly, the better preservation of the neuropils has led to the discovery and study of regional specializations that were previously undetected from silver preparations.     

热淋清糖浆的含量测定研究

目的用高效液相色谱法测定热淋清糖浆中没食子酸的含量。方法采用ODS C18柱(5μm,4.6×250mm),流动相为甲醇—水—N、N二甲基甲酰胺—冰醋酸(1.5:93:3.5:2),检测波长为262nm,流速为1.0mL.min-1,柱温:室温。结果没食子酸在0.105~0.70μg范围内线性关系良好(r=0.9999),方法的回收率为97.16%,RSD为1.04%(n=5)。结论该方法能准确可靠地进行含量测定,能够有效地控制该制剂的含量。     

儿茶素抑制二甲基肼诱发小鼠大肠癌的实验研究

昆明种小鼠随机分成７组，１～５组小鼠皮下注射二甲基肼（１，２－Ｄｉｍｅｔｈｙｌｈｙｄｒａｚｉｎｅ，ＤＭＨ），剂量２０ｍｇ／ｋｇｂｗ，每周一次，连续２０周。第２～５组于注射前一周开始灌胃儿茶素，每鼠每日分别为１ｍｇ、２ｍｇ、４ｍｇ、没食子酰表没食子儿茶素［（－）－Ｅｐｉｇａｌｌｏ－ｃａｔｅｃｈｉｎｇａｌｌａｔｅ］２ｍｇ，第６组给儿茶素３ｍｇ作为对照组，每周连续５次至２３周。第７组为溶剂对照组。２７周处死小鼠，结果显示：两组对照组小鼠未发现肿瘤。ＤＭＨ组大肠癌发生率为８０％，与２～５组比较明显升高（Ｐ＜０．００１），结果提示：（１）不同剂量的儿茶素都具有防癌作用，其机理可能与诱导ＳＯＤ等抗氧化剂的活性消除有害自由基有关；（２）其抑癌有效成分可能是多种儿茶素协同作用的结果；（３）儿茶素对个鼠无毒性作用。     

维生素D2的增溶与稳定性的研究

3种结构类型不同的增溶剂对维生素D₂的增溶效应,聚氧乙烯蓖麻油类大于聚氧乙烯脱水山梨醇脂肪酸酯类及聚氧乙烯脂肪醇醚类。在聚氧乙烯蓖麻油类C-125中维生素D₂的稳定性亦大于其余的两种增溶剂。在吐瘟80胶团中丁基羟基茴香醚主要位于胶团的栅层深部,由于可与维生素D₂处于胶团的相同部位,故较位于栅层浅部及水相之中的没食子酸丙酯,有效地延缓了维生素D₂的自动氧化作用。     

影响薄片法血小板聚集实验的因素

目的:研究常见影响因素对薄片法血小板聚集实验(SPAT)时间的影响.方法:测定下列富含血小板血浆(PRP)的SPAT:①调整血小板计数分别为240,120,60,30和15×109/L的8例健康献血者PRP;②分别在40,35,30,25,20,15,10和5℃条件下恒温30 min的10例健康献血者PRP;③含终浓度为0,10,20,30,40和50g/L的二甲基亚砜(DMSO)并室温放置30 min的10例健康献血者PRP;④在室温放置1,2,3,4 h后的8例健康志愿者服用阿司匹林前后PRP;⑤含浓度分别为0,0.5,1.0,2.0和3.O U/L的肝素或0.1 g/LEDTA的8例健康献血者PRP.结果:①随着血小板计数的降低,SPAT时间逐渐延长;同一供者血小板计数与其SPAT时间呈显著的直线负相关(r=0.996,P=0.004);②温度在20～40℃对SPAT时间无明显影响,但当温度低于20℃时SPAT时间明显延长;③DMSO对SPAT有明显的影响,使SPAT时间明显延长,并呈明显的剂量效应;④血小板标本室温放置1,2,3和4 h SPAT无显著差异(P=0.815);⑤肝素对SPAT时间无明显影响,而0.1 g/L乙二胺四乙酸(EDTA)可完全抑制血小板聚集.结论:血小板计数、所处的温度以及含有DMSO时,均能在一定程度上影响SPAT时间,但是上述因素均不影响血小板最终形成肉眼可见的聚集,且聚集时间仍然在180 s以内.     

表没食子儿茶素没食子酸酯对肝癌细胞增殖的抑制作用研究

目的 探讨表没食子儿茶素没食子酸酯(EGCG)对肝癌细胞HepG2增殖和凋亡的影响及其可能机制.方法 采用不同浓度(0、25、50、100、200、400mg/L)EGCG作用于HepG2细胞,于24、48h后采用MTT方法检测细胞增殖抑制率.以不同浓度(0、50、100、200mg/L)EGCG作用于HepG2细胞,24h后采用流式细胞术检测细胞凋亡率、细胞周期、细胞分裂周期蛋白25A(CDC25A)及Smad3蛋白的表达,RT-PCR检测CDC25A和Smad3 mRNA的表达.结果 MTT检测结果显示,不同浓度EGCG对HepG2细胞均有生长抑制作用,且具有时间和剂量依赖性(P＜0.01).随着EGCG浓度升高,细胞增殖指数(PI)明显降低(P＜0.01),细胞凋亡率明显增高(p＜0.01),CDC25A蛋白和mRNA表达水平下降(p＜0.05),Smad3蛋白和mRNA表达水平上升(p＜0.05).结论 EGCG可能通过下调CDC25A、上调Smad3的表达,抑制HepG2细胞增殖并诱导其凋亡,从而对肝癌细胞起到生长抑制作用.