2型糖尿病和非酒精性脂肪肝病患者的胰岛素抵抗和胰岛β细胞功能

目的 探讨2型糖尿病(T2DM)和非酒精性脂肪肝病(NAFLD)患者胰岛β细胞功能和胰岛素抵抗的特征.方法 206例研究对象根据是否有T2DM和NAFLD分为4组,采用肝脏胰岛素抵抗指数(HIR)、HOMA胰岛素抵抗指数(HOMA-IR)及Matsuda指数(MSI)评估胰岛素抵抗性,采用HOMA-β、早相及晚相胰岛素分泌指数评估胰岛β细胞功能.结果 NAFLD组和T2DM伴NAFLD组的HIR均显著高于对照组和T2DM组(4.13±0.64,4.03±0.69比3.52±0.78,3.53±0.64,P<0.05),T2DM伴NAFLD组的HOMA-IR显著高于T2DM和NAFLD组(3.35±2.69比2.31±1.39,2.40±1.55,P<0.05);NAFLD组的早相胰岛素分泌指标显著低于对照组(2.13±0.17比2.61±0.13,P<0.05),而T2DM组和T2DM伴NAFLD组的HOMA-β、早相及晚相胰岛素分泌指标均明显低于对照组(P<0.05).结论 NAFLD患者主要表现为肝脏胰岛素抵抗,其胰岛β细胞早相胰岛素分泌受损;T2DM患者存在胰岛素抵抗,其胰岛β细胞早、晚相胰岛素分泌功能均受损.当患者既有T2DM又有NAFLD时,胰岛素抵抗将更严重.     

胰岛β细胞的胰岛素抵抗

近年发现胰岛β细胞同样具有胰岛素的信号转导途径，同时也存在胰岛素抵抗。β细胞自身的胰岛素抵抗会导致葡萄糖刺激的一相胰岛素分泌异常，抑制β细胞增殖，促进β细胞凋亡。肥胖可以促进胰岛β细胞胰岛素抵抗的发生发展。胰岛β细胞自身胰岛素抵抗可能是2型糖尿病发病的中心环节。     

Visfatin转基因对胰岛β细胞功能和活性的影响

目的 探讨Visfatin基因过表达对胰岛β细胞增殖、凋亡、细胞周期和胰岛素释放的影响.方法 将MIN6细胞分为对照组、绿色荧光蛋白转染组和Visfafin转染组,对照组以空质粒、绿色荧光蛋白转染组以荧光蛋白质粒、Visfatin转染组分别以2、5、10 mg/L Visfatin质粒转染细胞,40、60 h后收集细胞,采用实时聚合酶链反应和Western blot法检测Visfatin mRNA和蛋白表达,应用噻唑蓝法及流式细胞仪检测细胞增殖、凋亡和周期,运用酶联免疫法检测葡萄糖刺激的胰岛素释放.采用单因素方差分析进行统计学分析.结果 与对照组相比,2、5、10 ms/L Visfatin质粒转染40 h及5 mg/L Visfatin质粒转染60 h后细胞增殖率分别升高1.60、1.87、1.75、1.51倍(t值分别为4.98、13.52、11.02、6.14,均P<0.05).棕榈酸诱导的细胞凋亡率降低,与对照组和绿色荧光蛋白转染组相比,质粒转染组细胞凋亡率分别降低42%、48%(F值分别为4.58、6.12,均P<0.05).与对照组相比,Visfatin质粒转染40 h后G_0/G_1期细胞减少12.3%,S期细胞增加13.2%(F值分别为5.25、6.23,均P<0.05).与对照组相比,质粒转染组细胞基础胰岛素分泌无改变,葡萄糖刺激后胰岛素释放有所增加,差异无统计学意义(P>0.05).结论 Visfatin可促进胰岛β细胞增殖,抑制胰岛β细胞凋亡,对细胞周期有调节作用.     

miR-200b通过靶向调控Ets-1对白介素-1β诱导胰岛β细胞损伤的保护作用

目的探讨miR-200b靶向Ets-1对白介素(IL)-1β诱导胰岛β细胞损伤的保护作用。结果体外培养大鼠胰岛β细胞株RINm5F,采用IL-1β诱导RINm5F细胞损伤,将RIN-m5F细胞分为对照组、损伤组(0.5 ng/ml IL-1β)、空转染组(0.5 ng/ml IL-1β+空载体)和过表达组(0.5 ng/ml IL-1β转染+miR-200b mimics),采用qRT-PCR检测转染48 h各组的miR-200b和Ets-1 mRNA水平,采用MTT法、FITC-Annexin V/PI双染流式细胞术及酶联免疫吸附法检测各组转染12、24、48及72 h的细胞存活率、凋亡率及胰岛素水平,检测各组细胞内谷胱甘肽过氧化物酶(GSHPx)、丙二醛(MDA)水平、总抗氧化能力(T-AOC)及超氧化物歧化酶(SOD)活性。结果与对照组相比,损伤组、空转染组的miR-200b水平降低,Ets-1 mRNA水平升高,但过表达组的miR-200b水平升高,Ets-1 mRNA水平降低(P0.05)。损伤组、空转染组转染后的存活率、上清液胰岛素水平及GSH-Px、T-AOC和SOD活性低于对照组,MDA水平和凋亡率高于对照组(P0.05);过表达组的以上指标均优于对照组(P0.05),但与对照组均有统计学差异(P0.05)。结论上调miR-200b水平对IL-1β诱导胰岛β细胞损伤有保护作用,主要表现在提高细胞存活、促进胰岛素分泌及改善氧化应激,可能与其靶向作用Ets-1有关。     

孕妇在不同糖耐量状态下胰岛素抵抗和胰岛β细胞功能的改变

目的 研究孕妇在不同糖耐量状态下胰岛素抵抗(IR)和胰岛β细胞功能的改变.方法 分析51例妊娠糖尿病(GDM)孕妇、45例糖耐量低减(GIGT)孕妇和119例糖耐量正常(NGT)孕妇的IR和胰岛β细胞分泌功能,采用稳态模式胰岛素抵抗指数(HOMA-IR)评价胰岛素抵抗,稳态模式胰岛B细胞功能指数(HBCI)和30分钟净增胰岛素/30分钟净增血糖(△130/△G30)评价胰岛β细胞分泌功能.结果 从NGT、GIGT到GDM,HOMA-IR呈递增,而HBCI和△DO/△G30呈递减倾向,差异均有统计学意义(P＜0.05～0.01);HBCI、△130/△G30与2hPG呈明显负相关(r分别=0.144,0.258,P均＜0.01);HBCI与△130/△G30呈明显正相关(r=0.144,P＜0.05).结论 妊娠期胰岛素抵抗增加和胰岛β细胞分泌功能下降是GDM的发病原因,且在GIGT阶段胰岛素早期分泌功能已受损.     

细胞内基质金属蛋白酶2基因过表达对INS-1细胞功能的影响

目的探讨细胞内基质金属蛋白酶2(MMP-2)基因过表达对大鼠胰岛β细胞株INS-1细胞功能的影响。方法采用基因重组技术将大鼠MMP-2cDNA插入真核表达载体pcDNA 3.1(+)构建大鼠MMP-2真核表达质粒,培养INS-1细胞。随机分为正常对照组,空质粒转染组及MMP-2质粒转染组。脂质体Lipofectmine 2000转染INS-1细胞,观察INS-1细胞内MMP-2基因和蛋白表达量变化,MMP-2酶活性变化,以及INS-1细胞凋亡情况与胰岛素分泌功能的变化。结果与正常对照组、空质粒转染组比较,MMP-2质粒转染组MMP-2mRNA表达增加(P均0.05),蛋白表达水平和酶活性上调(P均0.05);MMP-2质粒转染组细胞凋亡率(56.07±3.68)%高于正常对照组(33.70±6.53)%及空质粒转染组(38.02±5.60)%(P0.05),而IRI(1.30±0.27)低于正常对照组(3.37±0.76)与空质粒转染组(2.90±0.84)(P0.05)。结论细胞内MMP-2基因的过表达可引起胰岛β细胞凋亡增加,胰岛素分泌功能下降。     

初诊2型糖尿病患者胰岛β细胞功能观察

目的观察初诊2型糖尿病患者胰岛β细胞功能。方法250例患者进行口服葡萄糖耐量试验(OGTT)及胰岛素释放试验(IRT)。按HOMA模型计算HOMAIS,HOMAIR用逐步多元线性回归模型分析影响胰岛素分泌功能的因素。结果(1)随FPG升高,胰岛β细胞功能逐步下降;FPG≥8.2mmol/L,下降明显(P<0.05);FPG≥11.1mmol/L,出现空腹胰岛素水平下降;FPG≥13.9mmol/L,细胞功能进一步衰退(P<0.01)。(2)逐步回归分析显示:胰岛β细胞功能与FPG呈显著负相关,与胰岛素水平和胰岛素抵抗呈显著正相关(P均<0.01)。结论随着初诊2型糖尿病患者FPG升高,胰岛素分泌功能呈不同水平下降;高血糖的毒性作用最终导致胰岛素分泌功能衰竭。因此,必须尽早给予严格的血糖控制,保护β细胞功能,延缓β细胞衰竭。     

FoxO1基因沉默对胰岛素抵抗细胞葡萄糖消耗的影响及其机制

目的 探讨抑制叉头状转录因子O1(FoxO1)基因表达对胰岛素抵抗HepG-2细胞葡萄糖消耗的影响及可能机制.方法 构建针对转录因子FoxO1 mRNA特异性的携带红色荧光标记的siRNA载体,并测序鉴定.高浓度(10-6mol/L)胰岛素诱导24 h建立胰岛素抵抗细胞模型.实验共分4组:A组为普通培养基培养的细胞组;B组为未处理胰岛索抵抗细胞组;C组为转染FOxO1 siRNA载体的胰岛素抵抗细胞组;D组为以转染试剂为对照的胰岛素抵抗细胞组.转染后荧光显微镜下观察红色荧光的表达;葡萄糖氧化酶法检测各组细胞葡萄糖的消耗;RT-PCR技术检测FOxO1 mRNA表达;Western印迹和免疫沉淀技术检测胰岛素受体底物2(IRS-2)蛋白表达及酪氨酸磷酸化水平.结果 经测序,成功构建了FoxO1 siRNA 载体.在转染后48 h,细胞内红色荧光表达最强.此时,与A组比较,B组葡萄糖消耗量降低(P<0.01),FoxO1 mRNA表达增强(P<0.05),IRS-2蛋白表达无显著性差别(P>0.05),但其酪氨酸磷酸化明显降低(P0.05).结论 抑制FoxO1基因在胰岛素抵抗细胞中的高表达,可改善胰岛素敏感性,其机制可能是通过反馈调节IRS-2蛋白酪氨酸磷酸化,增强胰岛素信号转导.     

Galectin-8蛋白对组织工程心脏瓣膜种子细胞的增殖、黏附功能的影响

目的体外研究Galectin-8在不同浓度或状态下对组织工程心脏瓣膜种子细胞增殖及黏附的影响。方法以骨髓间充质干细胞分化而来的内皮细胞作为种子细胞,离体状态下常规培养。采用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐(MTT)法测定不同浓度下Galectin-8作用12、24、48 h后对细胞增殖的影响;将细胞分为重组质粒p GFP-Galectin-8转染组、空质粒p GFP转染组、阴性对照组及蛋白预铺组,分别铺于96孔板中,观察相同时间段的细胞黏附数量。结果 Galectin-8 10、20、40μg/ml剂量组的细胞增殖数目均显著高于空白对照组,其中20μg/ml组表现尤为显著(P<0.05);p GFP-Galectin-8转染组的转染效率与空质粒p GFP转染组无显著差异(P>0.05),且Galectin-8的表达量显著高于空质粒p GFP转染组和阴性对照组(P<0.05);细胞种植到培养板上1、2、4 h后,蛋白预铺组相同时间的细胞黏附数量显著高于其他各组(P<0.05),p GFP-Galectin-8转染组的细胞黏附数量显著小于其他各组(P<0.05),空质粒p GFP转染组和阴性对照组的细胞黏附数量无显著差异(P>0.05)。结论 Galectin-8对内皮细胞的增殖具有促进作用,且在细胞种植前预铺蛋白固定后能够显著增加内皮细胞的黏附,而胞内Galectin-8过表达则抑制细胞黏附。     

KATP通道开放剂与β细胞休息学说

2型糖尿病发病的中心环节为胰岛素抵抗和β细胞功能受损。胰岛素抵抗、高胰岛素血症及持续的糖毒性可加剧胰岛β细胞功能衰竭。大量研究表明,KATP通道开放剂(二氮嗪)开放KATP 通道,可强制过度疲劳的β细胞休息,抑制胰岛素的分泌,增加胰岛内胰岛素含量,恢复了胰岛素的脉冲式分泌,从形态和功能上保护了β细胞。适度的胰岛休息可以减轻β细胞的代谢压力,提高β细胞功能,是值得今后重点研究的方向。     

Changes in the liver weight in the elderly

To elucidate the effect of aging on liver weight in the elderly, 582 elderly cases (male 291, female 291), were selected from 2000 elderly autopsied cases on the basis of being free from pathological findings affecting liver weight. Both liver weight and its ratio to body weight decreased with age, and influenced by obesity; the former increased and the latter decreased in obese cases. Analysis according to the degree of obesity also showed decrease of liver weight and is ratio to body weight with age. Comparison between males and females of the same decade revealed the tendency that in females the liver weight was low, while liver weight.body weight ratio was high. The same results were obtained by analysis based on the degree of obesity.     

Oxprenolol in the treatment of hypertension in the elderly

Controversy continues to surround the value of drug treatment of hypertension in the elderly. Epidemiologic evidence implicates hypertension as a major risk factor in the precocious development of stroke and coronary heart disease in the elderly subject as clearly as it is implicated in the younger person. The hemodynamic and neuroendocrine profiles of the older patient with essential hypertension are similar to those of younger patients in the stable phase of the disease. However, the arterial ravages induced by many years of sustained hypertension render the circulation of the elderly subject more sensitive to pharmacologic intervention. The benefit-risk ratio of most antihypertensive drugs appears to be inversely related to age. Diuretics reduce the blood pressure at rest but have no influence on the increases in systolic pressure during normal activity; in addition, they carry potentially serious metabolic hazards in the elderly hypertensive patient. Centrally acting drugs likewise lower the blood pressure at rest without influencing the high systolic pressures induced by exercise. They also enhance the tendency to endogenous depression. Adrenergic-neurone blocking drugs and alpha-adrenoceptor antagonists are contraindicated because of the frequency of impaired cardiovascular reflexes in the elderly. The beta-blocking drugs can reduce the risk of coronary and cerebrovascular disease in the older patient with hypertension. They appear to be well tolerated, but because of their impaired metabolic handling in many elderly patients they should probably be used in smaller doses than those prescribed in younger patients. The influence of antihypertensive treatment on cardiovascular morbidity and mortality in the elderly hypertensive patient is not known.     

On the Role of the Septal Area in the Development of Doca-Salt Hypertension in the Rat

The extensive destruction of forebrain noradrenergic nerve terminals by the intraventricular injection of 250 μg of 6-hydroxy-dopamine prevents the subsequent development of DOCA-salt experimental hypertension in rats while the lesser destruction of noradrenergic nerve terminals produced by 90 μg of 6-hydroxydopa does not. The greatest difference in brain part noradrenaline levels between these two neurotoxins was in the septal area where noradrenaline was less than 15% of controls after 6-hydroxydopamine but was the same as controls after 6-hydroxydopa. The non-specific destruction of the lateral septal area by radiofrequency lesions prevented the subsequent development of DOCA-salt hypertension. The relatively selective destruction of catecholamine nerve terminals in the lateral septal area by the injection of 1 μg 6-hydroxydopamine in 1 μl vehicle also prevented the development of DOCA-salt hypertension. These data suggest that the lateral septal area may be the location of the forebrain catecholaminergic neural activity that is necessary for the development of DOCA-salt experimental hypertension in rats.