膳食脂肪、胰岛素抵抗与代谢综合征

代谢综合征是多种代谢异常同时发生于同一个体的临床现象,胰岛素抵抗是代谢综合征的中心环节.膳食中脂肪的摄入总量和种类的不同都与胰岛素敏感性密切相关.当脂肪供能占总热量35%～40%以上时,会降低胰岛素敏感性.脂肪供能占总热量的35%～40%以下时,强调摄入脂肪酸的类型比脂肪摄入总量更为重要.人体研究表明饱和脂肪酸(SFA)增加胰岛素抵抗,而单不饱和脂肪酸(MUFA)和n-6多不饱和脂肪酸(PUFA)可改善胰岛素敏感性,n-3 PUFA对人体胰岛素敏感性没有影响.代谢综合征中的其他代谢异常成分也均受到膳食脂肪的影响.     

015 膳食脂肪、胰岛素抵抗与代谢综合征

代谢综合征是多种代谢异常同时发生于同一个体的临床现象，胰岛素抵抗是代谢综合征的中心环节。膳食中脂肪的摄入总量和种类的不同都与胰岛索敏感性密切相关。当脂肪供能占总热量35％-40％以上时，会降低胰岛素敏感性。脂肪供能占总热量的35％～40％以下时。强调摄入脂肪酸的类型比脂肪摄入总量更为重要。人体研究表明饱和脂肪酸（SFA）增加胰岛素抵抗，耐单不饱和脂肪酸（MUFA）和n-6多不饱和脂肪酸（PUFA）可改善胰岛素敏感性，n-3 PUFA对人体胰岛素敏感性没有影响。代谢综合征巾的其他代谢异常成分也均受到膳食脂肪的影响。     

脂肪细胞因子与胰岛素抵抗关系研究进展

肥胖是2型糖尿病发生的危险因素之一,此时机体处于一种低度炎症状态^[1],在这种状态下,脂肪细胞因子的分泌发生变化.脂肪组织是胰岛素抵抗的始发部位,能合成和分泌多种活性物质,包括脂联素(Ad iponectin)、瘦素(Leptin)、抵抗素(Resistin)、促分裂原活化蛋白激酶(MAPK)等,它们在肥胖与胰岛素抵抗的发生发展过程中具有重要作用.目前,脂肪细胞因子已成为探求糖尿病及其他内分泌疾病发病机制的热点.现将脂联素、瘦素、抵抗素、促分裂原活化蛋白激酶(MAPK)与胰岛素抵抗的关系综述如下.     

膳食脂肪与胆固醇对血胆固醇的作用

大量流行病学证据表明血浆胆固醇浓度的升高，尤其是低密度脂蛋白（ＬＤＬ－Ｃ）浓度升高，是动脉硬化性心脏病的重要危险因素，而高密度脂蛋白（ＬＤＬ－Ｃ）浓度的升高对动脉硬化性心脏病有保护作用。越来越多的研究发现，血浆胆固醇浓度及种类脂蛋白的比较除受遗传和代谢的调节外，膳食因素对其也产生重要作用，由于膳食因素是一个重要的生活方式因素，也是一个可改变的因素，对心血管病预防有重大的实际意义，因此，膳食变化对血     

不同膳食脂肪对糖耐量及胰岛素敏感性的影响

目的:比较4种膳食脂肪对大鼠糖耐量及胰岛素敏感性的影响。方法:将50只SD大鼠随机分为5组,分别为紫苏油组、葵花籽油组、橄榄油组、猪油组和基础饲料组。各膳食脂肪组大鼠的脂肪摄入量占总能量的30.4%。喂养6 w后,进行口服葡萄糖耐量试验(OGTT),测定血清胰岛素、甘油三酯、总胆固醇等指标,并计算胰岛素敏感指数(ISI)。同时分离附睾脂肪垫并称重。结果:与基础饲料组相比,猪油组大鼠葡萄糖餐后2 h血糖及胰岛素显著升高,ISI显著降低;葵花籽油组和橄榄油组大鼠的餐后2 h血糖显著低于猪油组,ISI显著高于猪油组;紫苏油组大鼠空腹及餐后2h血糖、胰岛素水平均显著低于猪油组,ISI高于猪油组,其中空腹血糖还低于葵花籽油组、橄榄油组和基础饲料组,ISI高于上述组。紫苏油组血清甘油三酯、总胆固醇水平显著低于猪油组和基础饲料组,大鼠附睾脂肪垫相对重量显著低于猪油组。结论:猪油可促使胰岛素抵抗及高血糖的发生,而紫苏油可提高大鼠胰岛素敏感性、改善糖代谢;葵花籽油和橄榄油对胰岛素敏感性和糖耐量的作用介于紫苏油和猪油之间。紫苏油对糖代谢的有利作用可能与其降低血中甘油三酯水平、减少体内脂肪堆积有关。     

膳食脂肪与乳腺癌关系的Meta分析

乳腺癌是影响妇女健康十分常见的恶性肿瘤,国内外对其病因曾进行过大量的研究,认为乳腺癌是多因素疾病.近年来,动物实验表明脂肪摄入量与乳腺癌有因果关系.随着我国人民生活水平提高,国内学者日益重视脂肪摄入量与乳腺癌关系的研究,但研究结果尚不一致.为此,本文采用Meta分析的方法,对国内有关脂肪摄入量与乳腺癌关系的研究资料进行综合分析评价,为防止我国妇女乳腺癌发病率进一步增长寻找可行途径.     

脂肪细胞因子与代谢综合征关系研究进展

代谢综合征(metabolic syndrome,MS)是以中心性肥胖、糖尿病或糖调节受损、高血压、血脂异常以及胰岛素抵抗(in-sulin resistance,IR)为共同病理生理基础,以多种代谢性疾病合并出现为临床特点的一组临床症候群^〔1〕。1997年,Zem-met认为上述病症的共同病理基础是IR导致的糖及脂肪代谢紊乱,故建议统称为代谢综合征^〔2〕。近年来,人们对MS的认识不断深入,特别是很多学者通过大规模流行病学和临床试验研究,已公认肥胖是MS最重要的危险因素,并已证实脂肪组织也是内分泌器官,而且是机体最大的内分泌器官,可以释放瘦素、抵抗素、脂联素、肿瘤坏死因子等数10种脂肪因子。     

吉林省延边地区朝鲜族和汉族学生肥胖和胰岛素抵抗与脂肪细胞因子的关系

目的调查延边地区朝鲜族和汉族学生肥胖和胰岛素抵抗(IR)及其相关脂肪细胞因子,分析肥胖和IR与不同脂肪细胞因子的关联程度。方法在吉林省延边朝鲜族自治州选择4所小学校,采用整群抽样的方法,抽取3879例小学生(朝鲜族2011例和汉族1868例)作为研究对象,通过问卷调查和体格检查的方式,调查研究对象的一般情况,测定体质指数(BMI)、腰围(WC)和空腹血糖(FBG)、胰岛素、脂联素、瘦素及肿瘤坏死因子-α(TNF-α)水平。采用稳态模式评估法(HOMA)估测人体IR(HOMA-IR)。结果 (1)朝鲜族学生的脂联素水平显著低于汉族学生,朝鲜族学生的瘦素、HOMA-IR、WC和BMI的水平显著高于汉族学生,不同民族学生上述指标平均水平比较差异均有统计学意义(P<0.01)。(2)BMI、WC和HOMA-IR与脂联素呈负相关(r=-0.178、-0.172和-0.137),其与瘦素(r=0.572、0.535和0.265)和TNF-α(r=0.110、0.119和0.691)呈正相关,其相关性均有统计学意义(P<0.001),而且朝鲜族和汉族学生肥胖和HOMA-IR与不同脂肪细胞因子的相关性程度有所不同。(3)多元线性回归分析结果显示,BMI、WC和HOMA-IR与不同脂肪细胞因子间均有显著的线性依存关系,且与脂联素(Beta=-0.022、-0.019和-0.042)、瘦素(Beta=0.154、0.069和0.039)和TNF-α(Beta=-0.082、0.018和0.654)的关联程度有所不同。结论延边地区小学生不同肥胖指标、HOMA-IR和脂肪细胞因子的分布特征出现明显的民族差异;BMI、WC和HOMA-IR与不同脂肪细胞因子的关联程度有所不同,BMI和WC与瘦素的关联程度大于HOMA-IR,HOMA-IR与脂联素和TNF-α的关联程度大于BMI和WC。     

脂肪因子与餐后高血糖的研究进展

近年研究发现,脂肪组织是具有内分泌功能的器官。它分泌瘦素、脂联素、肿瘤坏死因子-α、抵抗素、内脂素等脂肪因子。这些细胞因子可能通过参与炎性反应与物质能量的代谢过程,影响胰岛素的生物学效应,影响餐后血糖水平。本文就近年来一些较多关注的脂肪因子与餐后高血糖关系作一综述,为临床控制餐后高血糖,从而降低心血管事件、预防代谢综合征提供依据。     

肺癌表遗传学研究进展

表遗传学机制在肺癌的形成中占据重要地位,包括DNA的甲基化和组蛋白修饰,肺癌中与癌形成有关基因的失活多与异常甲基化有关,并且组蛋白修饰和甲基化紧密联系着。表遗传学改变多发生在肺癌早期,使得它成为肺癌化学预防的优良指标,了解肺癌表遗传现象的机制及其与传统遗传学的相互作用关系将有利于发现安全、高效的化学预防药物。     

Types and amount of dietary fat and colon cancer risk: Prevention by omega-3 fatty acid-rich diets

Colorectal cancer is the second most common malignancy in the Western world including the United Sates. In recent years there is a strong upward trend in colon cancer risk in Japan mainly due to Americanization of Japanese food habits. Several epidemiological studies point to a strong association between nutrient composition of the diet and cancer of the colon. The role of types of dietary fat, especially saturated fats of animal origin, n−6- and n−3-rich polyunsaturated fatty acids (PUFAs) in the etiology of colorectal cancer has become increasingly apparent. Epidemiological studies indicate a positive association between the dietary intake of saturated fat and/or animal fat and colon cancer risk and an inverse relationship between the intake of fish and fish oil rich in n−3 PUFAs and colon cancer development. Although the evidence from case-control studies and international correlational studies is not totally consistent, these inconsistencies may have arisen, at least in part, from methodological limitations. Animal, model studies have unequivocally provided evidence that the colon tumor-promoting effect of dietary fat depends on its fatty acid composition and that high dietary n−3 PUFAs lacks colon tumor-promoting effect, as compared to diets high in n−6 PUFAs or saturated fats. Diets rich in n−3 PUFAs inhibit colon carcinogenesis through the modulation of colonicras-p21, cyclooxygenase-2, and inducible nitric oxide synthase activities and apoptosis. Gene expression analysis using DNA microarrays indicates that n−3 fatty acid, docosahexaenoic acid activates cyclin-dependent kinase inhibitors such as p21, p27, p57 and p19 and inactivates antiapoptotic Bcl-2 family of genes, and prostagland in family of genes. These results suggest that decreasing the intake of n−6 PUFAs and saturated fats and increasing that of n−3 PUFAs, particularly eicosapentaenoic acid and docosahexaenoic acid has the potential to be a major component of colon cancer control.     

水甘油通道蛋白7、9与肥胖和2型糖尿病发生研究进展

糖尿病是一种代谢紊乱疾病,其病因不是单一的,而是复合病因综合征,严重影响着人们的生活质量。随着分子生物学技术飞速发展,人们对糖尿病的认识也更加深入,许多学者开始在体液代谢异常上展开研究。水甘油通道蛋白作为介导甘油的通道,参与脂肪合成与分解等一系列重要的代谢过程,因而水甘油通道蛋白及其相关基因的研究,对糖尿病的治疗与控制的意义非常重大。     

Influence of dietary fat on beta-carotene absorption and bioconversion into vitamin A

Dietary fat facilitates the utilization of carotenoids and, based on serum beta-carotene or retinol responses following ingestion of meals containing carotene and fat sources, it has been reported that the amount of fat required in a meal may be minimal (approximately 3-5 g). However, the dietary fat requirement for optimal carotene utilization in humans cannot be fully ascertained without longer-term dose-response studies that measure the changes in vitamin A body stores in response to varying levels of dietary fat. In humans, vitamin A body stores can be determined by use of stable isotope-dilution methods. Animal studies have shown that although the level of dietary fat has no effect on serum vitamin A concentrations of animals fed beta-carotene, higher liver vitamin A concentrations were found in those that ingested higher fat levels. Other factors that might influence the relationship of fat intake and beta-carotene utilization include the type of fat ingested, physicochemical properties of the carotenoid source, amount of carotene ingested, whether fat and beta-carotene sources are provided in the same meal, the presence of helminthic infections, age, and vitamin A status.     

miRNAs参与调控肺癌发生发展的研究进展

摘要: miRNA是一类内源性非编码单链小分子RNA,通过对细胞中多种信号通路的调节影响细胞的增殖、凋亡等过程,其表达异常会导致包括癌症在内的很多疾病。根据功能的不同,在癌症发生发展过程中,异常表达的miRNA通常被分为致癌miRNA和抑癌miRNA两大类。本综述中主要阐述了一些参与肺癌发生发展的microRNA发挥致癌或抑癌作用的最新机制及研究成果,为深入了解肺癌的发病机制提供基础,同时也为肺癌的诊断及治疗提供新的视角。     

Trends in serum total cholesterol and dietary fat intakes in New Zealand between 1989 and 2009

Objective : To describe trends in serum cholesterol and dietary fat intakes for New Zealand adults between 1989 and 2008/09. Methods : Serum total cholesterol concentrations and dietary fat intakes were analysed for 9,346 New Zealanders aged 15–98 years (52% women) who participated in three national surveys in 1989, 1997 and 2008/09. Results : Population mean serum cholesterol decreased from 6.15 mmol/L in 1989 to 5.39 mmol/L in 2008/09. Mean saturated fat intake decreased from 15.9% of energy intake in 1989 to 13.1% in 2008/09. Between 1997 and 2008/09, unsaturated fat intake increased and fat from butter and milk decreased. Older adults had the largest decrease in serum cholesterol (1.35 mmol/L). Conclusions : The decrease in serum cholesterol is substantially larger than reported for many other high‐income countries, and occurred in parallel with changes in dietary fat intakes and, for older adults, increased use of cholesterol‐lowering medications. Implication : Given the demonstrated role of reduced saturated fat intake on lowering serum cholesterol, and as population average serum cholesterol levels and saturated fat intakes exceed recommended levels, initiatives to further encourage reductions in saturated fat are imperative.     

Formulation of practical advice for reducing dietary fat intakes in unemployed in Dublin

Patterns of food and nutrient intake in a sample of 97 adults in a region of Dublin with chronically high unemployment were examined. Food intake (g/10 MJ/day) of the upper and lower quartiles of intakes of selected nutrients were compared. Quartiles of fat intake were expressed as percentage energy from fat or as g/day. In both cases, but most notably in the former, the intake of table sugar was inversely related to the intake of fat. Again irrespective of the mode of expression, the high-fat diets were characterised by high intakes of spreadable fats. The high intakes of sugar seen with low intake of fat (g/day or percentage energy) were not associated with an absolute diminution of macronutrient (excluding sugar or energy) intake or of micronutrient intake.     

糖耐量减退患者血脂的改变与胰岛素抵抗的关系

目的:探讨糖耐量减退(IGT)患者血脂成分的改变及其与胰岛素抵抗(IR)程度的关系.方法:收集28例正常糖耐量(NGT)者和新诊断的55例IGT患者的临床资料,分别测定血脂谱.利用稳态模型胰岛素抵抗指数(HOMA-IR)量化IR程度.结果:IGT患者血清甘油三酯(TG)与低密度脂蛋白-胆固醇(LDL-C)水平显著高于NGT组(P<0.05及P<0.01),高密度脂蛋白-胆固醇(HDL-C)值明显低于NGT组(P<0.001).IGT患者HOMA-IR显著高于NGT组(P<0.01).HOMA-IR与TG水平呈正相关(r=0.32,P<0.01),与LDL-C呈正相关(r=0.26,P<0.05).HOMA-IR与HDL-C负相关(r=-0.27,P<0.05).结论:新诊断的IGT患者已经存在血脂代谢异常,且与IR密切相关.