菩达茶降血糖作用临床观察

目的　观察菩达茶降血糖作用的临床疗效。方法　 2型糖尿病患者 70例 ,随机分为菩达茶组 38例和安慰剂组 32例 ,治疗组口服菩达茶 ,1个月为 1个疗程 ,观察 2组糖尿病患者症状改善情况 ,检测空腹血糖及餐后 2h血糖、尿糖、空腹血清胰岛素指标。结果　菩达茶组总有效率为 5 2 .63% ;安慰剂组总有效率为 1 2 .5 0 %。 2组比较有显著性差异(P <0 .0 1 )。菩达茶组在改善患者多数主要症状方面优于安慰剂组 (P <0 .0 5或P <0 .0 1 ) ;菩达茶组的空腹血糖和餐后 2h血糖均较治疗前明显降低 (P <0 .0 1 ) ,并且其降低值与安慰剂组比较有显著性差异 (P <0 .0 1 ) ;菩达茶组的糖耐量治疗后较治疗前明显下降(P <0 .0 1 ) ,与安慰剂组比较有显著性差异 (P <0 .0 5 ) ;对尿糖、血清胰岛素无影响。结论　菩达茶能明显降低 2型糖尿病患者空腹血糖 ,有效改善糖耐量异常 ,对多饮、多食、夜尿多等症状有较好的改善作用 ,对血清胰岛素水平无明显影响     

茶多酚对新生大鼠卵巢发育的影响

目的:探讨茶多酚对新生大鼠卵泡发育和卵母细胞凋亡的影响及相关调控机制。方法:受孕11.5dSD大鼠灌胃茶多酚(100mg/kg,qd)直至分娩,分别用多聚甲醛固定出生后1d、2d、4d、8d龄雌仔鼠卵巢(A组),同时将正常出生后1d的雌幼SD大鼠腹腔注射茶多酚(50mg/kg×1-8d),分别固定出生后2d、4d、8d龄卵巢(B组);所有卵巢经HE染色,观察不同发育阶段的卵泡比例,TUNEL(TdT-mediated dUTP Nick-End Labeling)荧光染色检测卵巢内卵母细胞凋亡变化,免疫组化方法观察叉头转录因子(FOXO3a)、促凋亡因子(Bim)和抗凋亡因子(MnSOD2)在卵巢组织中的表达水平,并以母、幼均未处理的正常同龄大鼠卵巢为对照(C组)。结果:在茶多酚干预组(包括A组和B组)卵巢内,1d、2d龄未装配卵泡比例及4d、8d龄原始卵泡比例均高于C组;A组、B组中卵母细胞TUNEL阳性率显著低于C组;FOXO3a、MnSOD2在A组的1d、2d、4d龄卵巢中的表达高于C组,但二组间的Bim表达水平相一致。结论:茶多酚能延缓新生大鼠卵母细胞巢破裂,抑制原始卵泡的发育启动,减少卵泡的消耗,可能有益于延长卵巢的生殖寿命;茶多酚可能通过上调FOXO3a的活性从而抑制原始卵泡的发育启动,同时通过激活其下游靶分子MnSOD2抑制卵母细胞的凋亡,促进卵母细胞的存活。     

Choice of exposure scores for categorical regression in meta-analysis: a case study of a common problem

Objective: Reporting categorical relative risk estimates for a series of exposure levels versus a common reference category is a widespread practice. In meta-analysis, categorical regression estimates a dose–response trend from such results. This method requires the assignment of a single score to each exposure category. We examined how closely meta-analytical categorical regression approximates the results of analysis based on the individual-level continuous exposure.Methods: The analysis included five studies on tea intake and outcomes related to colorectal cancer. In addition, we derived categorical mean and median values from published distributions of tea consumption in similar populations to assign scores to the categories of tea intake when possible. We examined whether these derived mean and median values well approximate the individual-level results.Results: In meta-analytical categorical regression, using the midrange scores approximated the individual-level continuous analyses reasonably well, if the value assigned to the uppermost, open-ended category was at least as high as the lower bound plus the width of the second-highest category. Categorical mean values derived from the published distributions of regular tea (in the US) and green tea (in Japan) well approximated the slope obtained from individual-level analysis.Conclusion: Publication of both the categorical and the continuous estimates of effect in primary studies, with their standard errors, can enhance the quality of meta-analysis, as well as providing intrinsically valuable information on dose–response.     

Green tea and the risk of breast cancer: pooled analysis of two prospective studies in Japan

In a pooled analysis of two prospective studies with 35004 Japanese women, green-tea intake was not associated with a lower risk of breast cancer (222 cases), the multivariate relative risk for women drinking >or=5 cups compared with <1 cup per day being 0.84 (95% confidence interval 0.57-1.24, Trend P=0.69).     

茶多酚对人结肠癌细胞株Caco-2凋亡及RhoA蛋白活性的影响

目的探讨茶多酚对人结肠癌细胞株Caco-2凋亡及RhoA蛋白活性的影响。方法将传代后的人结肠癌细胞株Caco-2细胞分为实验组和对照组,实验组加入不同浓度的茶多酚（25、50、100和200μmol／L）,对照组加入等量RPMI-1640培养液,采用四甲基偶氮唑盐（MTr）法测定茶多酚对Caco-2增殖抑制的影响,流式细胞术（FCM）检测细胞凋亡指数,Pull．down法检测人结肠癌细胞株Caco-2细胞内的RhoA蛋白活性。结果不同浓度的茶多酚对人结肠癌细胞株Caco-2有明显的抑制作用,且呈剂量及时间依赖性;Pull-down法检测结果显示,茶多酚可以降低人结肠癌细胞株Caco-2细胞内的RhoA蛋白活性,且随浓度增加其蛋白活性降低。结论茶多酚可促进人结肠癌细胞株Caco-2的凋亡,其可能通过降低RhoA蛋白活件来实现。     

Chemical constituents from Qianliang tea

Ten compounds were isolated from Qianliang tea, a kind of dark tea fully fermented from the leaves of Camellia sinensis (L.) O. Kuntze var. sinensis, and identified as N-(2-hydroxyphenyl)-2-pyrrolidinone (1), p-hydroxyacetophenone (2), salicifoliol (3), (-)-3-hydroxy-β-ionone (4), p-hydroxy ethyl cinnamate (5), ethyl 4-(sulfooxy)benzoate (6), (+)-matairesinol (7), (-)-pinoresinol (8), (+)-lirioresinol-A (9), and caffeine (10), among which compound 1 was isolated as a new natural product, and compound 6 was isolated from Theaceae family for the first time. Compounds 3, 4, 5, 7, 8, and 9 were isolated from this species for the first time.     

Beverage-induced enhanced bioavailability of carbamazepine and its consequent effect on antiepileptic activity and toxicity

The present study was undertaken to investigate the food–drug interaction of carbamazepine (CBZ). Common fruit juices [grapefruit juice (GFJ), lime juice (LJ)], known to inhibit the enzyme cytochrome P450 3A4 (CYP3A4), and some widely consumed beverages [milk (M), black tea (BT)] were involved in this study in the presence of CBZ, as might happen during clinical therapy. The effects of the beverages on the pharmacokinetics and drug-induced toxicity of CBZ was observed after concomitant administration for a period of 28 days. Accordingly, the influence of altered bioavailability of CBZ on its antiepileptic activity was investigated. A significant shift in the C_max as well as T_max of CBZ was observed in the presence of LJ and GFJ. This increase in bioavailability significantly enhanced hepatotoxicity and delayed the onset of tremor and piloerection against pentylene tetrazole (PTZ)-induced seizure in experimental animals. However, increased toxicity of CBZ was found to be absent with BT. Thus, from our observation, LJ or GFJ in the presence of CBZ significantly increased the bioavailability of CBZ, which might lead to increased toxicity and antiepileptic activity of the drug.     

Coffee, tea, caffeine and risk of breast cancer: a 22-year follow-up

The relation between consumption of coffee, tea and caffeine and risk of breast cancer remains unsettled. We examined data from a large, long-term cohort study to evaluate whether high intake of coffee and caffeine is associated with increased risk of breast cancer. This was a prospective cohort study with 85,987 female participants in the Nurses' Health Study. Consumption of coffee, tea and caffeine consumption was assessed in 1980, 1984, 1986, 1990, 1994, 1998 and the follow-up continued through 2002. We documented 5,272 cases of invasive breast cancer during 1,715,230 person-years. The multivariate relative risks (RRs) of breast cancer across categories of caffeinated coffee consumption were: 1.0 for <1 cup/month (reference category), 1.01 (95% confidence interval: 0.92-1.12) for 1 month to 4.9 week, 0.92 (0.84-1.01) for 5 week to 1.9 days, 0.93 (0.85-1.02) for 2-3.9 days, 0.92 (0.82-1.03) for >or=4 cups per day (p for trend = 0.14). Intakes of tea and decaffeinated coffee were also not significantly associated with risk of breast cancer. RRs (95% CI) for increasing quintiles of caffeine intake were 1.00, 0.98 (0.90-1.07), 0.92 (0.84-1.00), 0.94 (0.87-1.03) and 0.93 (0.85-1.01) (p for trend = 0.06). A significant inverse association of caffeine intake with breast cancers was observed among postmenopausal women; for the highest quintile of intake compared to the lowest RR 0.88 (95% CI = 0.79-0.97, p for trend = 0.03). We observed no substantial association between caffeinated and decaffeinated coffee and tea consumption and risk of breast cancer in the overall cohort. However, our results suggested a weak inverse association between caffeine-containing beverages and risk of postmenopausal breast cancer.     

绿茶对交链孢霉代谢物致突变性的抑制作用

观察绿茶对交链孢酚单甲醚(AME)和B_(2-a6)提取物诱导人胚肺2BS细胞SCE的影响。结果表明:不同浓度的绿茶,均不能增加SCE的频率,但在绿茶存在的情况下,由AME(10μg/ml)和B_(2-a6)(0.1mg/ml)所诱导的SCE频率比没有绿茶时低(P<0.01),并呈剂量—效应关系。结果提示:绿茶对某些霉菌毒素的致突变性有抑制作用。