儿童血清脂肪细胞因子与肥胖和非酒精性脂肪肝的关联

目的 研究白细胞介素-6(IL -6)、血浆纤溶酶原激活物抑制剂1(PAI -1)、视黄醇结合蛋白4(RBP -4)水平在非酒精性脂肪肝(NAFLD)、肥胖儿童血清中的变化,为儿童NAFLD血清学标志物的发现提供依据.方法 采用双抗体夹心酶联免疫吸附法,测定儿童血清IL -6、PAI -1、RBP -4水平.结果 体重正常组与肥胖组IL -6、PAI -1水平差异均无统计学意义(P值均＞0.05),体重正常组RBP -4水平显著高于肥胖组(P＜0.01);NAFLD组的IL -6水平明显高于非NALFD组(P＜0.01),NAFLD组的RBP -4水平显著低于非NAFLD(P＜0.01);未见NAFLD组与非NAFLD组之间PAI -1水平存在差异(P＞0.05).NAFLD分度与IL -6水平呈正相关(β=0.168,P=0.013),与RBP-4呈负相关(β=- 0.262,P=0.001).结论 肥胖儿童RBP-4水平低于正常体重儿童;IL -6及RBP -4与儿童NAFLD有关,可能在儿童脂肪肝的发病过程中起一定作用.     

NOD1在肥胖糖尿病患者脂肪细胞中的表达及对胰岛素抵抗的作用

【目的】探讨肥胖糖尿病（DM）患者脂肪细胞免疫受体核苷酸结合寡聚化结构域蛋白1（nucleotide-binding oligomerization domain-containing protein,NOD1）的表达与胰岛素抵抗的关系。【方法】取10例肥胖 DM患者（DM组）及10例非DM肥胖患者（NDM组）腹部皮下脂肪细胞,采用Real-time PCR方法检测两组脂肪细胞受体 NOD1的表达,加入 NOD1受体激动剂 iE-DAP,用酶联免疫吸附法（ELISA）检测两组细胞炎性细胞因子白细胞介素（IL）-6、IL-8及单核细胞趋化因子1（MCP-1）水平,2-脱氧-3 H-D-葡萄糖摄入法观察基础状态和 iE-DAP刺激状态的葡萄糖摄取率。【结果】DM组脂肪细胞 NOD1 mRNA的表达显著高于 NDM组（P＜0．05）;iE-DAP刺激下DM组 IL-6、IL-8及 MCP-1的分泌水平均显著高于 NDM组（P ＜0．05）,DM组胰岛素刺激状态下脂肪细胞葡萄糖摄取率显著低于 NDM组（P＜0．05）。【结论】NOD1介导的炎症反应可能参与肥胖糖尿病胰岛素抵抗的发生。     

兔骨髓间质干细胞定向诱导分化为脂肪细胞

目的　体外定向诱导兔骨髓间质干细胞 (MSC)分化为脂肪细胞。方法　采用Ficoll Paque淋巴细胞分离液分离RMSC ,体外扩增 ,并用地塞米松、3 异丁基 1 甲基黄嘌呤 (IBMX)、胰岛素、消炎痛定向诱导RMSC分化为脂肪细胞。油红O检测中性脂肪 ,光镜下细胞计数。结果　兔骨髓间质干细胞在体外扩增 5代可获得 1× 10 8个细胞。诱导 4 8h后 ,细胞内有脂滴出现 ,随着诱导时间延长 ,脂滴逐渐增加并融合为脂泡 ,细胞由梭形转变为圆形或多角形。细胞计数结果显示 6 3%以上细胞转变为脂肪细胞。结论　兔骨髓间质干细胞在体外可以分化为脂肪细胞。     

Increased insulin resistance and fat cell lipolysis in obese but not lean women with a high waist/hip ratio

Increased lipolysis in abdominal adipocytes has been suggested to be of importance for the insulin resistance typical for abdominal obesity. In order to differentiate between fat distribution, measured as waist/hip ratio (WHR), and amount of body fat, glucose disposal during a euglycaemic clamp as well as lipolysis in isolated cells from abdominal and gluteo-femoral regions were studied in 20 obese and 20 lean postmenopausal women with a high (n = 10) and low (n = 10) WHR, respectively. The lipolytic response was increased in cells from obese women irrespective of region. Furthermore, lipolysis was enhanced in abdominal compared with the gluteo-femoral cells in obese women with a high WHR. Fasting blood glucose and insulin were increased in both groups of obese women while the degree of insulin resistance was most pronounced in the obese women with a high WHR. It is concluded that increased body fat is associated with both insulin resistance and increased lipolysis, and that this relationship is stronger in the presence of a high WHR. A high WHR may increase the expression of obesity as a risk for insulin resistance and this may be mediated through an increased lipolytic rate.     

Clonal osteogenic cell lines express myogenic and adipocytic developmental potential

Summary Clonal osteoblastic cell lines were isolated from neonatal rat calvariae and characterized with regard to a number of features associated with authentic osteoblasts. These included elevated alkaline phosphatase activity (relative to fibroblasts), PTH and PGE₂-stimulated increases in cAMP, the predominant synthesis of type 1 collagen, and the production of a mineralized matrixin vitro. By these criteria, five clones with osteoblast-like phenotypes were identified (ROB-C8a, C11, C20, C23, and C26) which varied somewhat in shape, levels of alkaline phosphatase activity, and in responsiveness to PTH and PGE₂, C11, C20, and C23 responded to both effector substances, whereas C8a only responded to PTH and C26 only responded strongly to PGE₂. Upon further examination, two of the clones (C23 and C26) were also found to exhibit significant muscle myotube formation after reaching confluence, and three of the clones (C8a, C11, and C26) showed marked adipocyte differentiation after treatment with dexamethasone. Overall, these data add further supporting documentation to (1) the suspected ontogenetic relationships of osteoblasts to other connective tissue cells, and (2) the concept that osteoblastic cells associated with neonatal rat calvariae are in various stable stages of differentiation and developmental commitment.     

大鼠骨髓基质细胞体外成脂、成骨分化的研究

目的　观察体外定向诱导大鼠骨髓基质细胞分化为脂肪细胞和成骨细胞。方法　全骨髓法分离大鼠骨髓基质细胞 ,传 3代后分别在成脂、成骨诱导条件下继续培养 ,油红O染色、碱性磷酸酶染色和VonKossa染色判定其分化结果。结果　传 3代大鼠骨髓基质细胞成脂诱导 2 1d后 ,分化为脂肪细胞的阳性率为 (83. 6± 2 . 8) % ,成骨诱导 12d后碱性磷酸酶染色阳性率达 (87. 6± 2. 8) % ,连续诱导35d可见矿化结节形成。结论　随着诱导条件的不同 ,大鼠骨髓基质细胞在体外可定向分化为脂肪细胞或成骨细胞。     

Evidence of altered calcium accumulation and calcium binding by the membranes of adipocytes in spontaneously hypertensive rats

Calcium accumulation and calcium binding (ATP-dependent and ATP-independent calcium uptake) by the fragmented plasma membrane, the cytoplasmic reticulum and the mitochondria of isolated adipocytes obtained from spontaneously hypertensive (SHR, Kyoto-Wistar) and normotensive Wistar and Kyoto-Wistar rats were studied by means of isotopic (⁴⁵Ca) exchange in vitro.The value of Ca accumulation in the cytoplasmic reticulum fraction of adipocytes obtained from SHR was found decreased, while in the mitochondrial fraction it was considerably greater as compared to those in both normotensive control groups. Ca binding (ATP-independent) by the plasma membrane fraction of hypertensive rats was less than that of the normotensive rats. There was no difference between the groups studied in calcium binding ability for the cytoplasmic reticulum fraction of adipocytes.These results seem to indicate that the adipose cells of hypertensive rats have an alteration of the membrane mechanism maintaining intracellular calcium distribution.     

Insulin binding to target cells

Summary Following Yalow and Berson's basic research on the binding of polvpeptide hormones to plasma proteins, an integrated picture of hormone-receptor interaction and biological activity has been proposed for insulin in experimental models and in man. The extracellular interaction of the insulin molecule with the cell membrane structure modifies the intracellular metabolism, and it has been suggested that this occurs through the activation of a second messenger or the trans. duction of an insulin fragment into the cell. The use of monoiodoinsulin has made it possible to perform a series of experiments on cells isolated from the blood (monocytes) or from the tissues (adipocytes) and on plasma membranes prepared by ultracentrifugation. The existence of specific receptor sites for insulin in all cases, both in animals and in man, has been confirmed by mathe matical analysis of the binding curves; their non-linear course as plotted by Scatchard's method, may depend on negative cooperation or on different classes of receptor. From an evaluation of recent studies on human obesity, particularly on adipocytes and circulating monocytes, a new approach to the problem of ‘insulin resistance’ in obesity has been proposed, and this has shown that a reduction in the number of receptors on the target cells may contribute to peripheral insulin insensitivity. This phenomenon, which seems to be characteristic of the static phase of obesity, is reversible during fasting or weight reduction and may be a compensatory mechanism for hyper-insulinaemia. These results are an example of the significance and applicability of the experimental method of detecting insulin binding to target cells, and suggest a wide application in different endocrinological fields.     

A small reduction in glomerular filtration is accompanied by insulin resistance in type I diabetes patients with diabetic nephrophathy

BACKGROUND: Insulin sensitivity and insulin clearance are compromised in end-stage renal disease but it has not been fully established whether they are altered in earlier stages of diabetic nephropathy. DESIGN: We studied three groups of patients with type 1 diabetes; 10 with no sign of nephropathy, 11 with albuminuria (> 20 microg min-1) but normal glomerular filtration rate (GFR) and eight with a small reduction in GFR, (43-73 mL min-1 1.73 m-2). The groups were matched for age (range 36-61 years), body mass index (BMI), diabetes duration and glycaemic control. The euglycaemic hyperinsulinaemic clamp technique was utilized to study insulin sensitivity (M-value) and metabolic clearance rate for insulin. Needle biopsies from abdominal subcutaneous fat tissue were obtained to study insulin binding, insulin degradation, insulin-stimulated glucose uptake and anti-lipolysis in adipocytes in vitro. RESULTS: Patients with reduced GFR were more insulin-resistant (M-value 5.7 +/- 0.7 mg kg LBM-1 min-1) than those without nephropathy (9.6 +/- 0.7, P = 0.001) and those with only albuminuria (8.9 +/- 1.2, P = 0.044). In all subjects taken together there was a strong association between insulin sensitivity and GFR (r = 0.46, P = 0.012). Patients with reduced GFR displayed no significant difference in insulin clearance (12.2 +/- 1.6 mL kg-1 min-1) compared to controls (13.8 +/- 1.3) but a slightly lower insulin clearance than patients with only albuminuria (16.6 +/- 1.0, P = 0.027). There were no significant differences between patient groups in the adipocyte studies in vitro, i.e. with respect to insulin binding, insulin degradation and the effects of insulin on glucose uptake and lipolysis. This is compatible with humoral factors causing whole-body insulin resistance and in the group with reduced GFR, we found that serum parathyroid hormone, interleukin-6 and tumour necrosis factor-alpha levels were elevated whereas the morning cortisol was decreased. CONCLUSIONS: In type 1 diabetes, the appearance of albuminuria does not seem to alter insulin sensitivity and clearance. A marked insulin resistance but no consistent impairment in insulin clearance seems to accompany progression to a stage with a slight reduction in GFR. These alterations are not accompanied by general defects in insulin target cells. Instead, alterations in the regulation of insulin-antagonistic hormones and cytokines could potentially contribute to the development of insulin resistance in diabetic nephropathy.