谷胱甘肽S-转肽酶基因多态性与动脉粥样硬化发病机制的研究

既往研究已表明谷胱甘肽S-转肽酶(GSTs)存在基因多态性,这种突变可增加人体对癌源性物质及炎症性疾病的敏感性.近年的研究结果提示GSTs基因多态性与动脉粥样硬化密切相关,这种相关性使我们从分子水平上探讨动脉粥样硬化的发病机制,从而达到基于个体基因型采取预防及治疗措施.     

猪带绦虫囊尾蚴囊液谷胱甘肽S转换酶活性测定

目的：探讨猪带绦虫囊尾蚴囊液内谷胱甘肽Ｓ转换酶（ＧＳＴ）的活性。方法：测定酶催化反应后底物浓度的变化,计算ＧＳＴ活力单位。结果：囊液经１：２０稀释,重复４次测定酶促管与非酶促管吸光值,测得平均ＧＳＴ活性为６１．８４活力单位;囊液冻干品则几无ＧＳＴ活性。结论：囊液中存在游离形式的ＧＳＴ活性,对筛选保护性抗原和可能的化疗靶分子具有潜在意义。     

肝脏缺血再灌注损伤时大鼠血清谷胱甘肽及其相关酶活性的变化

目的 还原型谷胱甘肽（GSH）是体内重要的氧自由基的清除剂。本实验意在研究缺血肝脏复流后血清谷胱甘肽及其相关酶水平变化,及L－精氨酸对其水平的影响。方法 雄性SD大鼠90只随机分为3组;左中肝叶先行缺血70min,后恢复血流,于复流前静脉给予生理盐水（损伤组）,或复流前静脉给与L－精氨酸（200mg/kg)（处理组）;假手术组只给与暴露左中肝叶之肝蒂。各组动物在复流后0、1、3、6、12h取血清标本,用以检测丙氨酸氨基转移酶（ALT）、MDA、 还原型谷胱甘肽（GSH）,谷胱甘肽过氧化物酶（GSH－PX）和谷胱甘肽－S转移酶（GSH－ST）。并取肝组织标本做光镜和电镜观察,了解组织病变特点。结果 损伤组血清ALT、MDA、GSH－ST和GSH－PX含量较假手术组有明显的提高（P＜0．05）,而在复流后3h血清GSH水平明显降低（P＜0．05）。给与L－精氨酸处理可以明显减轻这种变化（P＜0．05）。结论 L－精氨酸对大鼠肝脏缺血再灌注损伤的保护作用可能与上调还原型谷胱甘肽水平有关。血清GSH－PT、GSH－ST活性受到肝细胞损伤后释放增加的影响,与肝脏损伤程度有关。     

谷胱甘肽对高糖时人内皮细胞分泌前列环素和内皮素-1的影响

了解谷胱甘肽（ＧＳＨ）对高糖时人内皮细胞分泌前列环素（ＰＧＩ２）和内皮素－１（ＥＴ－１）的影响。方法： 原代培养人脐静脉内皮细胞,分别加入正常对照组,高糖组,正常＋ＧＳＨ组,高糖＋ＧＳＨ组培养基,放免法测定培养 ２４ｈ,４８ｈ,７２ｈ时培养基中的ＰＧＩ２和ＥＴ－１含量。结果：①高糖组较正常对照组ＰＧＩ２显著下降（Ｐ＜０．０１）,ＥＴ－１显 著升高（Ｐ＜０．０１）;②高糖＋ＧＳＨ组较高糖组ＰＧＩ２升高（Ｐ＜０．０１）,ＥＴ－１显著下降（Ｐ＜０．０１）。结论：ＧＳＨ在调节高 糖时人血管内皮细胞分泌 ＰＧＩ２／ＥＴ－１的平衡方面起一定作用。     

胃癌及癌旁黏膜组织胎盘型谷胱甘肽S-转移酶的表达

①目的 探讨胎盘型谷胱甘肽Ｓ－转移酶（ＧＳＴπ）在胃癌中表达的意义。②方法 应用ＬＳＡＢ免疫组化方法检测了胃癌及癌帝黏膜组织ＣＳＴπ的表达。③结果 正常胃黏膜组织ＧＳＴπ阳性表达率为１６．７％,肠上皮化生和不典型增生腺体ＧＳＴπ阳性表达率分别为７１．４％和１００．０％,显著高于正常胃黏膜（Ｘ＾２＝８．４,１９．４,Ｐ〈０．０１）。胃癌组织中ＧＳＴπ阳性表达率为８０．３％,高分化腺癌和低分化腺癌ＧＳ     

愈肝汤对慢性乙肝患者脂质过氧化的影响

目的　探讨愈肝汤对慢性乙肝患者的脂质过氧化作用。方法　 43例慢性乙肝患者服愈肝汤治疗 3mo ,观察其治疗前后超氧化物歧化酶 (SOD)、谷胱甘肽过氧化物酶 (GSH -Px)活力和过氧化脂质(LPO)水平的变化 ,并与 38例健康对照组比较。结果　慢性乙肝患者SOD、GSH -Px活力降低 (P <0 .0 5 ) ,LPO水平升高 (P <0 .0 5 ) ;愈肝汤可升高SOD和GSH -Px酶活性 (P <0 .0 1) ,降低LPO水平 (P <0 .0 5 )。结论　愈肝汤对慢性乙肝患者有明显的抗脂质过氧化作用 ,这是其治疗慢性乙型肝炎、减轻肝细胞损伤的重要机理之一。     

HepG2 细胞谷胱甘肽含量和谷胱甘肽转移酶活力的诱导

目的：建立一种具有较高ＧＳＨ含量和ＧＳＴ活力的肝细胞系。方法：将ＨｅｐＧ２细胞在０．１,０．３,０．５ｍｇ／Ｌ浓度的ＣＤＤＰ间歇作用下传代１２个月后得到三种稳定的ＣＤＤＰ耐药细胞系ＨｅｐＧ２／ＣＤＤＰ０．１,ＨｅｐＧ２／ＣＤＤＰ０．３,ＨｅｐＧ２／ＣＤＤＰ０．５细胞的ＧＳＨ含量和ＧＳＴ活力,结果用显著性ｔ检验方法作统计学处理。结果：诱导刺激后的子代ＨｅｐＧ２／ＣＤＤＰ０．１,ＨｅｐＧ２／ＣＤＤＰ０     

Glutathione S-transferase activity in epithelial ovarian cancer: Association with response to chemotherapy and disease outcome

Background: Conflicting data have been reported about the associationbetween glutathione S-transferase (GST), a family of proteins implicated indetoxification of cytotoxic drugs in human ovarian in vitro models, andresponse to chemotherapy and prognosis in ovarian cancer patients. The aim ofthis study was to analyze the possible clinical role of GST activity in alarge series of primary ovarian cancer patients.Patients and methods: The study included a large series of primaryuntreated ovarian cancer patients who underwent cytoreductive surgery andchemotherapy and who were followed up in a single institution. GST activitylevels were assessed in tumor extracts by using a biochemical assay. A cut-offof 250 units of enzymatic activity was chosen according to the receiveroperating characteristics (ROC) curve.Results: GST activity levels were distributed in an asymmetrical manner(median: 266 units; range: 4–918 units) and did not seem to beassociated with stage, histopathological grading, ascites, or residual tumorafter surgery. Higher GST activity levels were found in patients who respondedto chemotherapy (median: 298 units, range: 50–691) than in those whoresponded only partially (median: 227 units, range: 19–747) or not atall to chemotherapy (median: 246 units, range: 4–811) (H = 7.02, P =0.029). Moreover, the percentage of cases with >250 units was significantlyhigher among complete responders (66%) than partial responders(37%) or non-responders (48%) (² = 7.32;P = 0.025). When multivariate analysis, including clinico-pathologicalparameters and GST activity status as predictors of response to chemotherapy,was carried out, residual tumor, stage and GST status retained independentpredictive value. Patients with high GST activity had more favourableprognosis than those with low GST activity. The median PFS was 42 months forpatients with high GST activity compared to 17 months for those with low GSTactivity (P = 0.037). The median overall survival was 72 months forhigh-GST-activity and42 months for low-GST-activity patients (P = 0.043). Substantially similarresults were obtained in the subgroup of stage II–III–IV ovariancancer patients. Multivariate analysis including the clinico-pathologicalparameters and GST activity status was performed in stage III–IV ovariancancer patients: Stage IV disease, residual tumor >2 cm, the presence ofascites and low GST activity status retained independent negative prognosticroles.Conclusion: A direct association between high GST activity and a betterclinical outcome in terms of response to chemotherapy and survival has beenobserved in a large series of primary untreated ovarian cancer patients. Theseresults, which are contrary to the expectations raised by in vitro studies,emphasize the need for caution when translating in vitro-generated hypothesesto the clinical setting.     

Role of calcium in thromboxane B2-mediated injury to rabbit gastric mucosal cells

A sustained increase in cytosolic Ca²⁺ can damage gastric mucosal cells. The present study has examined the role of Ca²⁺ in thromboxane B₂ (TXB₂)-mediated damage of rabbit isolated gastric mucosal cells. Cells were isolated from rabbit oxyntic mucosa by collagenase-EDTA digestion. Cell metabolic activity and cell damage were estimated by alamar blue dye absorbance and trypan blue uptake, respectively. Cellular Ca²⁺ was monitored by indo-1 dye fluorescence. Addition of TXB₂ (10^–6 and 10^–8 M) to the cell suspension resulted in a decrease in metabolic activity, and this effect was reduced when Ca²⁺ was removed from the incubation Ca²⁺ and incubation of cells with the intracellular Ca²⁺ chelator, BAPTA-AM (20 M), reduced cell injury in response to TXB₂. Incubation of cells with the Ca²⁺ ionophore A23187 (1–25 M) resulted in a dose-dependent increase in trypan blue uptake and a reduction in cell metabolism. Cell unjury in response to A23187 were exacerbated by addition of TXB₂ (10^–8 M) to the cell suspension. TXB₂ treatment reduced cellular content of reduced glutathione (GSH), while exogenous GSH addition (10 mM) reduced TXB₂-mediated cell injury. These data demonstrate that TXB₂ can directly injure gastric mucosal cells. Gastric mucosal cellular damage in response to TXB₂ is mediated in part by a disruption of Ca²⁺ homeostasis as well as a reduction in cellular GSH content.This work was supported by a grant from the Medical Research Council of Canada MT6426.     

Observations on the human cornea in vitro

Human corneas seem to have a vegetative physiology similar to the rabbits. The swelling-hydration characteristics of the stromas are similar and there is a pump in the endothelium which continuously pumps fluid out of the stroma. An electrical potential is found across the endothelium which is stimulated and stabilised in the presence of 0·5 mm reduced glutathione. Both fluid flow across the endothelium and trans-endothelial electrical potential are reversibly abolished in the absence of exogenous bicarbonate and CO₂ which suggests that the two phenomena are manifestations of a common underlying mechanism.Difficulties in using the specular microscope on human cornea in vitro are illustrated. It is suggested that results from such experiments usually cannot be interpreted.