高胰岛素血症,高脂血症致动脉粥样硬化的实验研究

使用加与不加高脂血清的不同胰岛素对培养的动脉平滑肌细胞进行刺激，以了解其光学及电结构改变。结果显示：胰岛促细胞生长强度与胰岛成正比，高脂血清使平滑肌细胞排列无序化，失去特征结构，变为泡沫细胞；胰岛素与高脂血清复合作用，不仅使细胞形态、结构改变，并使之由收缩型变为增殖型，还导致胶原纤维产生。结果提示：控制高胰岛素血症、高脂血症患者的血胰岛素、血脂水平，有助于预防和推迟动脉粥样硬化的产生和发展。     

Effects of a 7-day infusion of glucose on insulin secretion in vivo and in vitro in ventromedial hypothalamic-lesioned obese rats

Excessive stimulation of insulin secretion may be one cause of the beta-cell dysfunction induced by hyperglycemia. We investigated a possible link between the prior endogenous hypersecretion of insulin and this dysfunction by performing a 7-day glucose infusion (50% wt/vol, 1.2 ml/h) on ventromedial hypothalamic VMH-lesioned hyperinsulinemic rats. Intravenous glucose tolerance tests (IVGTT 1.0 g/kg) revealed that a 3-day glucose infusion enhanced the insulin responses in both the sham- and VMH-lesioned rats compared with saline infusions. A similar 7-day glucose infusion enhanced the insulin response to glucose in sham-lesioned rats but not in VMH-lesioned rats. Batch-incubation of islets isolated from sham-lesioned rats showed an enhanced insulin response to glucose after 7 days of glucose treatment compared with the saline infusions. Conversely, the glucose infusion in VMH-lesioned rats markedly suppressed the in vitro insulin response. In sham- and VMH-lesioned rats, similar islet insulin contents were produced by saline and glucose treatments. Electron microscopy revealed that glucose infusions impaired the granule-releasing function of the beta-cells in VMH-lesioned rats, while insulin synthesis was accelerated in either group. These findings support the notion that excessive secretion is partly responsible for the beta-cell dysfunction induced by hyperglycemia without signs of exhaustion. Received: 13 June 1997 / Accepted in revised form: 14 November 1997     

A comparison between Japanese-Americans living in Hawaii and Los Angeles and native Japanese: the impact of lifestyle westernization on diabetes mellitus

We have been conducting the Hawaii-Los Angeles-Hiroshima Study since 1970, mainly to determine the effects of environmental changes on various diseases by comparing Japanese-Americans with native Japanese subjects. Japanese-Americans living in Hawaii and Los Angeles are originated mainly from Hiroshima, Japan and are genetically identical with native Japanese. Through this study, we made several clear observations about Japanese-Americans. First, Japanese-Americans were highly exposed to a westernized lifestyle ; in other words, a relatively high fat and simple carbohydrate diet with low physical activity as compared to native Japanese. Second, the prevalence of type 2 diabetes among Japanese-Americans and death from ischemic heart disease among Japanese-American diabetic patients were higher. Third, the serum fasting insulin level as well as the insulin level after a glucose load, was higher among Japanese-Americans, even when the serum glucose levels were not statistically different as compared to native Japanese. Accordingly, Japanese-Americans were thought to have a high insulin resistance status. However, the initial insulin response after a glucose load was low, which was more similar to Japanese people than to Caucasians. Fourth, the total cholesterol and triglyceride levels were higher among Japanese-Americans. These results are supposed to be derived from the insulin resistant status by the westernization of lifestyle, as well as from the weakness of pancreatic beta cell function that is supposed to be genetically regulated among Japanese. In conclusion, it appears that for genetically Japanese people, environmental factors are important for the development of metabolic diseases such as diabetes mellitus and cardiovascular disease.     

Left ventricular function after chronic insulin treatment in diabetic and normal rats

Previous reports have documented a cardiomyopathy in rats resulting from streptozotocin-induced diabetes. In order to determine the reversibility of streptozotocin-induced cardiomyopathy to insulin therapy, hearts from rats made diabetic by streptozotocin for 6 weeks and then treated with insulin for 3 weeks were compared with untreated diabetic rats and control rats not injected with streptozotocin. When perfused in an isolated working heart apparatus with 5.5 mM glucose as substrate, hearts from untreated diabetic rats when compared to hearts from either streptozotocin-injected rats treated with insulin or control rats showed significant depressions in peak left ventricular pressure, maximal positive and negative dP/dt, oxygen extraction, lactate production and effluent lactate; pyruvate ratio. Ca2+-actomyosin ATPase was also depressed in untreated diabetics. As left atrial pressure was raised in untreated diabetic rats, a decline in cardiac output was observed, whereas in insulin-treated or control groups there was no such negative response. Indices of cardiac performance were significantly greater in insulin-treated rats when compared to control rats suggesting overcorrection with insulin therapy. To explore whether insulin treatment may have a beneficial effect on the myocardium control rats were made hyperinsulinemic for 6 to 7 weeks. Shorter isovolumic relaxation times and elevated values for Ca2+-actomyosin ATPase were observed in hearts from hyperinsulinemic animals when compared to hearts from control animals. These results demonstrate complete reversibility of streptozotocin-induced cardiomyopathy and confirm that this condition is due to insulin deficiency and not to a primary cardiotoxic effect of streptozotocin.     

老年糖尿病前期患者胰岛素抵抗和胰岛β细胞分泌功能

目的:研究老年空腹血糖异常(IFG)和糖耐量低减(IGT)患者的胰岛素抵抗(IR)和胰岛β细胞分泌功能。方法:将84例老年患者分为正常血糖组(NGT)、IGT组、IFG组和IGT与IFG重叠组(IFG/IGT),测定患者的空腹及餐后2h血糖和胰岛素,计算胰岛素敏感性指数(ISI)、胰岛β细胞分泌指数(HBCI)并进行对比性分析。结果:与NGT组比较IFG、IGT及IFG/IGT组的餐后2h血糖(2hPG)、空腹及餐后2h胰岛素(2hINS)水平均显著升高(P<0.01),但ISI均显著下降(P<0.01),IGT与IFG/IGT组HBCI明显降低(P<0.05);与IFG组比较IGT与IFG/IGT组FPG、2hPG、2hINS水平显著升高,HBCI明显下降(P<0.05~<0.01)。结论:IFG、IGT及IFG/IGT患者均存在明显IR,而胰岛β细胞分泌功能下降在IGT及IFG/IGT组患者明显。     

Insulin resistance and metabolic syndrome criteria in lean,normoglycemic college-age subjects

Aims

The goal of this study was to determine insulin sensitivity in a fasted state and during an oral glucose tolerance test (OGTT), in normoglycemic (NGT), lean (L) (n?=?35) and, for comparison, overweight/obese (OW/O) (n?=?9) college-aged subjects.

Fibroepithelial papillomatosis ("skin tags") in Rabson-Mendenhall syndrome

Rabson-Mendenhall syndrome is a rare autosomal recessive syndrome in children involving a defective insulin receptor gene. Several phenotypic features are common to this syndrome, including severe hyperinsulinemia, growth retardation, acanthosis nigricans, dental dysplasia, hirsutism, coarse facial features, and pineal hyperplasia. The authors evaluated and treated a patient with Rabson-Mendenhall syndrome who presented with additional notable syndromic sequelae including extensive fibroepithelial papillomatosis (“skin tags”), not previously described to this extent.     

The Role of Endocrine Insulin-Like Growth Factor-I and Insulin in Breast Cancer

Epidemiologic studies demonstrate that breast cancer is the most common type of cancer diagnosed in women and is a significant cause of morbidity and mortality. While there are many risk factors known to be associated with increased breast cancer risk, this review will focus specifically on circulating IGF-I, hyperinsulinemia, and type 2 diabetes. Their effects on promoting breast cancer development, progression, and adverse outcomes have been demonstrated in both animal and human studies, suggesting that the IGF system is a potential target for breast cancer therapy. In addition, in the clinical setting, emphasizing metabolic risk modifications to patients including weight loss, dietary changes, and diabetes control may also play an important role in breast cancer risk reduction. Dr. Derek LeRoith is presently a consultant and speaker and receives as honorarium from Merck, Sanofi-Aventis, Pfizer, Takeda, and Novo Nordisk.     

Exaggerated glucagon-like peptide-1 and blunted glucose-dependent insulinotropic peptide secretion are associated with Roux-en-Y gastric bypass but not adjustable gastric banding

BACKGROUND: The aim of this study was to measure the circulating levels of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and glucagon in patients who had undergone adjustable gastric banding (BND) or Roux-en-Y gastric bypass (RYGB) to understand the differences in glucose and insulin regulation after these procedures. METHODS: This was a cross-sectional study of 3 groups of women matched for age and body mass index: group 1, overweight controls (n = 13); group 2, BND (n = 10); and group 3, RYGB (n = 13). Venous blood was drawn with the patient in the fasted state and throughout a 3-hour period after a liquid meal. RESULTS: The fasting glucose level was similar between the 2 surgery groups; however, the fasting insulin concentrations were greater in the BND (10.0 microU/mL) than in the RYGB (6.2 microU/mL; P <0.05) group. The glucose level at 60 minutes was significantly lower in the RYGB group (70 mg/dL, range 38-82) than in the BND group (83 mg/dL, range 63-98). The GLP-1 levels at 30 minutes were more than threefold greater in the RYGB group (96 pmol/L) compared with the BND and overweight control (28 pmol/L) groups. The GLP-1 and insulin concentrations correlated at 30 minutes only in the RYGB group (r = .66; P = .013). The glucose-dependent insulinotropic peptide levels at 30 minutes were lower in the RYGB group (20 pmol/L) than in the BND group (31 pmol/L) or overweight control group (33 pmol/L). The peak glucagon levels were similar among the 3 groups. CONCLUSION: Exaggerated postprandial GLP-1 and blunted glucose-dependent insulinotropic peptide secretion after RYGB might contribute to the greater weight loss and improved glucose homeostasis compared with BND.