多囊卵巢综合征患者胰岛素受体基因外显子17的多态性研究

目的：探索胰岛素受体基因外显子17 的基因多态性与多囊卵巢综合症（PCOS）的关系,为多囊卵巢综合症的治疗寻找新的途径。方法：利用PCR-SSCP技术检测45 例多囊卵巢综合症患者（实验组）与40 例健康妇女（对照组）全血中胰岛素受体基因外显子17 位点1058 的基因多态性,同时测定PCOS 患者的一般指标及血清学指标。按照体重指数、胰岛素抵抗、有无高雄激素血症比较胰岛素受体基因外显子17位点1058 C、T等位基因出现的频率。结果：实验组患者T 等位基因出现的频率为71.2%,明显高于对照组的25%（P〉0.05）;实验组非肥胖组患者中T 等位基因出现的频率为69.2%,明显高于肥胖组患者的25%（P〈0.01）,亦高于对照组,差异具有统计学意义（P〈0.05）。根据胰岛素受体基因外显子17 出现T、C 基因的频率,将其分为1、2 两组,1 组出现T基因的频率的BMI（20.34± 2.47）明显低于2 组出现C 基因的频率的BMI（26.68± 5.52）;PCOS 患者胰岛素抵抗组与非胰岛素抵抗组中INSR 基因外显子17 出现T、C等位基因的频率无明显差别（P〉0.05）;PCOS 患者高雄激素组组与无高雄激素组中胰岛素受体基因外显子17 出现T、C等位基因的频率无明显差别（P〉0.05）。结论：胰岛素受体基因外显子17 中T/C 单核酸多态性表现与PCOS 患者的发病密切相关,T 等位基因的高发频率与非肥胖因型PCOS 患者的发病密切相关;瘦型PCOS 患者与肥胖型患者胰岛素抵抗的发病机制或许不同;T 等位基的高发频率与PCOS 的主要临床表现如：胰岛素抵抗、高雄激素血症并无明显相关关系。     

肿瘤坏死因子α基因rs4645843C/T多态对多囊卵巢综合征患者血清中睾酮浓度的影响

目的:探讨肿瘤坏死因子α基因外显子3中rs4645843C/T多态对多囊卵巢综合征患者睾酮浓度的影响。方法:应用聚合酶链反应-SNP敏感性分子开关技术检测130例多囊卵巢综合征(PCOS)患者和175例对照组妇女肿瘤坏死因子-α外显子3中rs4645843C/T多态及其分布,比较rs4645843C/T等位基因与PCOS之间的关系,同时采用化学发光法分析测定血清T水平。结果:PCOS及对照组TNF-α基因rs4645843C/T多态分析均显示有CC,CT,TT三种基因型和C,T两种基因。PCOS组中CC,CT,TT三种基因型和C,T两种等位基因频率分别为34.6%、58.5%、6.9%和63.8%,36.2%,对照组中三种基因型和两种等位基因频率分别为43.4%,53.7%,2.9%和70.3%,29.7%,基因型频率和等位基因频率分布差异在两组中均无统计学意义(P=0.108;P=0.093)。在PCOS患者中,各等位基因及基因型频率分布在高雄激素血症组(T≥0.7ng/mL)和非高雄激素血症组(T<0.7ng/mL)差别亦无统计学意义(P=0.867)。方差分析发现CC,CT,TT三种基因型患者之间血清T...     

脂联素基因单核苷酸多态性与Ⅱ型糖尿病合并肥胖及胰岛素抵抗相关联

脂联素是近年新发现的脂肪组织特异性的细胞因子,其mRNA是脂肪组织中含量最丰富的基因转录产物,该因子可通过多种途径影响个体对胰岛素的敏感性。脂联素基因多态性与肥胖、胰岛素抵抗和2型糖尿病密切相关,而与冠心病相关性研究的报道较少。本研究以中国汉族人群1,098例为对象,其中304例冠心病(CHD)患者,389例糖尿病患者(T2DM),及405例性别年龄相匹配的正常对照,采用PCR-RFLP技术对脂联素基因-4522C/T进行基因分型,并分别对血脂水平、胰岛素抵抗、体重指数等临床数据进行分析比较。研究结果显示,脂联素基因-4522C/T各基因型及等位基因在CHD组与对照组、T2DM组与对照组中的分布差异无显著性;经分组分析发现,T2DM合并肥胖患者BMI≥25kg/m2TT基因型及T等位基因明显多于对照组,差异有显著性,P=0.014和P=0.034;TT基因型T2DM患者胰岛素抵抗指数(HOMA-IR)显著高于携带有C等位基因的T2DM患者,P=0.0069。本研究提示脂联素基因-4522C/T与中国汉族人群T2DM合并肥胖的发生及T2DM患者胰岛素抵抗相关,是引发糖尿病患者肥胖和胰岛素抵抗的重要候选基因,而与冠心病的发生无关联。     

新疆维汉民族多囊卵巢综合征患者CYP17基因多态性及与发病机制的关系

目的:探讨细胞色素P450酶17(CYP17)基因多态性及其与多囊卵巢综合征(PCOS)发病机制的关系。方法:选择2015年1月~2017年2月我院收治的新疆维汉民族PCOS患者260例为PCOS组,另选取同期在我院门诊检查的健康育龄妇女237例为对照组,采用限制性片段长度多态性聚合酶链反应(PCR-RFLP)技术检测两组受试者的CYP17基因多态性,比较两组等位基因及基因频率的分布,结合其临床资料分析CYP17基因多态性与PCOS发病机制的关系。结果:PCOS组体质量指数(BMI)、卵泡刺激素(FSH)水平低于对照组,黄体生成激素(LH)、睾酮(TES)及黄体生成激素与卵泡刺激素的比值(LH/FSH)高于对照组,差异有统计学意义(P0.05)。PCOS组CYP17基因A1A1、A1A2、A2A2型频率分别为34.62%、41.92%、23.46%,与对照组的34.18%、43.88%、21.94%比较差异无统计学意义(P0.05);PCOS组等位基因A1、A2频率为55.58%、44.42%,与对照组的56.12%、43.88%比较差异无统计学意义(P0.05);PCOS组不同CYP17基因型者的FSH、LH及LH/FSH水平整体比较差异无统计学意义(P0.05);PCOS组BMI水平A2A2A1A2A1A1,TES水平A2A2A1A1A1A2,差异均有统计学意义(均P0.05);对照组不同CYP17基因型者的BMI、FSH、LH、TES及LH/FSH水平整体比较差异均无统计学意义(P0.05)。结论:CYP17基因-34bp处T/C单核苷酸多态性是人群中一种常见的碱基置换,与PCOS的发病机制无明显的相关性。     

Ⅱ型糖尿病患者APOA5-1131T/C基因多态性与血脂代谢和胰岛素抵抗的关系研究

为了探讨载脂蛋白A5基因(APOA5)-1131T/C多态性在中国镇江地区的频率分布及其与血浆脂质代谢和Ⅱ型糖尿病患者胰岛素抵抗的关系, 采用聚合酶链反应-限制性片段长度多态性分析(PCR-RFLP)结合琼脂糖凝胶电泳技术检测152例健康人及71例Ⅱ型糖尿病患者APOA5 -1131T/C基因型及等位基因频率分布, 同时采用生化方法测定所有研究对象的血脂、血糖和胰岛素水平。结果显示: 糖尿病组APOA5 -1131C等位基因频率显著高于对照组(0.430 vs 0.296, P = 0.006)。CC纯合子患糖尿病的风险是TT纯合子的3.75倍(OR = 3.75, 95% CI: 1.57~8.92), 且经Logistic回归分析, 校正年龄、BMI和血浆HDL-c、LDL-c及ApoB水平等其他混杂因素影响后, 这种差异仍具有显著性意义(OR = 2.70, 95%CI: 1.24 ~ 5.86)。糖尿病组C等位基因携带者TG水平显著高于非C等位基因携带者(P < 0.01), TC水平和LDL-c水平亦明显升高(P < 0.05)。但是在两组中, 不同基因型患者 胰岛素抵抗相关指标均无显示差异。提示APOA5-1131T/C单核苷酸多态性对人群血浆TG水平有影响, -1131C等位基因与血浆TG、TC和LDL-c水平增高有关, 但是与糖尿病患者胰岛素相关指标无关; APOA5 -1131C等位基因可能与人群糖尿病的发生相关联。     

多囊卵巢综合征肥胖患者血清维生素D、铁蛋白水平、sICAM-1与胰岛素抵抗、糖脂代谢指标的相关性

摘要 目的：探讨多囊卵巢综合征（PCOS）肥胖患者血清维生素D、铁蛋白、可溶性细胞间粘附分子-1（sICAM-1）水平与胰岛素抵抗、糖脂代谢指标的相关性。方法：2018年8月到2021年11月,选择在本院妇科诊治的PCOS患者65例作为研究对象,分为PCOS肥胖组（n=30,体重指数＜28 kg/m²）和PCOS非肥胖组（n=35,体重指数<28 kg/m²）。检测与计算两组清维生素D、铁蛋白、sICAM-1、胰岛素抵抗、糖脂代谢指标并进行相关性分析。结果：两组的血清甲状腺素（T4）、促甲状腺激素（TSH）与泌乳素（PRL）对比差异无统计学意义（P>0.05）,肥胖组的血清促黄体生成素（LH）、促卵泡生成素（FSH）、睾酮（T）水平高于非肥胖组（P<0.05）。肥胖组的血清铁蛋白、sICAM-1水平高于非肥胖组,血清维生素D水平低于非肥胖组（P<0.05）。肥胖组的胰岛素抵抗指数（HOMA-IR）、胰岛素水平（FINS）、甘油三酯（TG）、总胆固醇（TC）、低密度脂蛋白胆固醇（LDL-C）较非肥胖组,高密度脂蛋白胆固醇（HDL-C）低于非肥胖组（P<0.05）。在PCOS肥胖患者中,Pearson分析显示血清维生素D、铁蛋白、sICAM-1与胰岛素抵抗、糖脂代谢指标都存在相关性（P<0.05）。结论：PCOS肥胖患者与非肥胖患者的血清维生素D、铁蛋白、sICAM-1、胰岛素抵抗、糖脂代谢指标水平存在差异,血清维生素D、铁蛋白、sICAM-1水平与胰岛素抵抗、糖脂代谢指标存在相关性。     

多囊卵巢综合征患者血清抗苗勒管激素与肥胖、胰岛素抵抗程度的相关性分析

目的:探讨多囊卵巢综合征(polycystic ovary syndrome,PCOS)患者血清抗苗勒管激素(anti-Müllerian hormone,AMH)水平与肥胖、胰岛素抵抗(insulin resistance,IR)程度的相关性。方法:选择在我院生殖中心就诊的139名PCOS患者为研究组,并以月经周期正常、因输卵管因素或男性因素导致不孕者48名作为对照组。检测和比较PCOS患者的血清AMH、性激素水平及代谢指标,分析血清AMH水平与PCOS患者肥胖、胰岛素抵抗程度的关系。结果:PCOS组患者体质量指数(body mass index,BMI)、黄体生成素(luteinizing hormone,LH)、睾酮(testosterone,T)、垂体泌乳素(pituitary prolactin PRL)、空腹血糖(fasting plasma glucose,FPG)、空腹胰岛素(fasting insulin,FINS)、稳态模型胰岛素抵抗指数(homenostasis models assessment-insulin resistance index,HOMA-IR)的水平均显著高于对照组(P0.05),PCOS组和对照组年龄、卵泡刺激素(follicle stimulating hormone,FSH)比较差异无统计学意义(P0.05)。PCOS各表型组的血清AMH浓度、LH/FSH比值均明显高于对照组(P0.05)。肥胖组患者的AMH浓度低于正常体重组,BMI、FPG、FINS、HOMA-IR、甘油三脂(triglycerides,TG)水平均高于正常体重组,LH、LH/FSH、高密度脂蛋白(high density lipoprotein,HDL-C)水平均低于正常体重组(P0.05)。高HOMA-IR组患者的血清AMH浓度、LH、LH/FSH水平均明显低于低HOMA-IR组,BMI、T、FPG、FINS、TG、低密度脂蛋白(low density lipoprotein,LDL-C)水平均高于低HOMA-IR组(P0.05)。PCOS患者血清AMH浓度和BMI及HOMA-IR均存在显著负相关。结论:PCOS患者血清的AMH水平较对照组明显升高,与其肥胖、胰岛素抵抗(IR)程度呈显著负相关。     

内蒙古地区汉族多囊卵巢综合征患者临床特征研究

目的:分析总结多囊卵巢综合(Polycystic ovary syndrome,PCOS)合并不育患者的临床及内分泌代谢特征,为PCOS的临床诊治提供依据.方法:回顾性分析120例PCOS患者(其中肥胖型73例,非肥胖型47例)的临床特征及内分泌、空腹血糖(FPG)、空腹胰岛素(FINS)等检查指标.用稳态模型胰岛素抵抗指数(HOMA-IR)、稳态模型胰岛素分泌指数(HOMA-IS)、空腹胰岛素敏感指数(ISI)评估胰岛素敏感性.结果:两组患者睾酮(T)、黄体生成素(LH)、卵泡刺激素(FSH)、LH/FSH无显著差别.肥胖组的FPG和FINS水平明显高于非肥胖组.两组胰岛素抵抗(IR)发生率分别为86.30%和51.06%.肥胖组的IR、ISI均明显高于非肥胖组.结论:PCOS患者肥胖发生率较高,肥胖型PCOS患者较非肥胖型患者存在更严重的代谢紊乱.减重、改善IR不仅可以改善PCOS不育情况,更是预防2型糖尿病、心血管疾病等远期并发症的关键.     

多巴胺D1受体基因多态性与注意缺陷多动障碍的相关性研究

目的:探讨多巴胺D1受体(Dopamine D1 receptor, DRD1)基因启动子区G-48A、外显子区T1403C两个SNP位点与注意缺陷多动障碍(attention deficit hyperactivity disorder,ADHD)的关联性.方法:选取87名ADHD患者和103名正常对照,提取基因组DNA,采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)技术检测G-48A和T1403C两个多态性位点的基因型,SPSS13.0软件分析各位点的等位基因及基因型频率.结果:DRD1的G-48A基因型及等位基因频率分布在ADHD和对照组之间有统计学差异(p<0.05),ADHD组中等位基因A频率显著高于正常组(p<0.05).T1403C位点基因型及等位基因频率在ADHD组与健康对照组无统计学差异.结论:DRD1基因G-48A多态性可能与ADHD的发病有关,携带有等位基因A的个体可能更容易患ADHD.T1403C多态性与ADHD的发病无明显相关性.     

多囊卵巢综合征的小鼠模型

多囊卵巢综合征(polycystic ovary syndrome,PCOS)是育龄女性最常见的生殖内分泌紊乱性疾病之一,其主要的临床特征包括多毛、不排卵或稀发排卵、高雄激素血症、多囊化卵巢、肥胖、血脂紊乱和胰岛素抵抗等生殖和代谢异常两方面。理想的PCOS动物模型应同时具有类PCOS患者的生殖和代谢异常表型,从而为更好地理解PCOS的病理机制提供研究工具。本文综述了目前常用的PCOS小鼠模型,并总结了不同模型的生殖与代谢特征。     

Regulation of insulin secretion and GLUT4 trafficking by the calcium sensor synaptotagmin VII

Insulin regulates blood glucose by promoting uptake by fat and muscle, and inhibiting production by liver. Insulin-stimulated glucose uptake is mediated by GLUT4, which translocates from an intracellular compartment to the plasma membrane. GLUT4 traffic and insulin secretion both rely on calcium-dependent, regulated exocytosis. Deletion of the voltage-gated potassium channel Kv1.3 results in constitutive expression of GLUT4 at the plasma membrane. Inhibition of channel activity stimulated GLUT4 translocation through a calcium dependent mechanism. The synaptotagmins (Syt) are calcium sensors for vesicular traffic, and Syt VII mediates lysosomal and secretory granule exocytosis. We asked if Syt VII regulates insulin secretion by pancreatic beta cells, and GLUT4 translocation in insulin-sensitive tissues mouse model. Syt VII deletion (Syt VII -/-) results in glucose intolerance and a marked decrease in glucose-stimulated insulin secretion in vivo. Pancreatic islet cells isolated from Syt VII -/- cells secreted significantly less insulin than islets of littermate controls. Syt VII deletion disrupted GLUT4 traffic as evidenced by constitutive expression of GLUT4 present at the plasma membrane of fat and skeletal muscle cells and unresponsiveness to insulin. These data document a key role for Syt VII in peripheral glucose homeostasis through its action on both insulin secretion and GLUT4 traffic.     

胰岛素抵抗在前列腺癌治疗前后动态变化的临床观察

目的:探讨胰岛素抵抗程度在前列腺癌治疗过程中动态变化及胰岛素抵抗程度与前列腺癌预后的关系。方法:选择前列腺癌惠者50名。平均年龄72岁。将前列腺癌患者根据治疗方法分为前列腺癌根治术组、手术去势组、药物去势组;根据有无复发转移分为复发转移组、无复发转移组。采用己糖激酶法测定空腹葡萄糖,放免法测定空腹胰岛素(Fasting serum insulin FINS)水平。运用HOMA模型中的胰岛素抵抗计算公式计算胰岛素抵抗指数(insulin resistance index IRI)。组间比较采用配对t检验。结果:前列腺癌患者在手术后的胰岛素抵抗指数明显下降,与手术前胰岛素抵抗指数存在统计学差异(P<0.05)。前列腺癌根治组的IRI值和手术去势组与药物去势组都存在统计学差异(P<0.05),但手术去势组和药物去势组两组之间不存在统计学差异(P>0.05)。前列腺癌治疗后无复发转移组的IRI值明显低于复发转移组,两组间IRI存在统计学差异(P<0.05)。结论:前列腺癌患者胰岛素抵抗程度与肿瘤治疗经过、效果有关。胰岛素抵抗指数有助于前列腺癌患者判断治疗效果,判断预后。     

Effect of alterations in membrane lipid unsaturation on the properties of the insulin receptor of Ehrlich ascites cells

We have altered the phospholipid composition of the plasma membranes of Ehrlich ascites cells grown in mice and studied the effects on the properties of the insulin receptor of this cell. The insulin receptor of the Ehrlich cell demonstrated all of the binding characteristics of mammalian insulin receptors: specificity for insulin and insulin analogs, saturability, inverse relationship of steady-state binding levels to temperature, and negative cooperativity. Cellular phospholipids enriched in monounsaturated fatty acyl groups were produced by growth in animals that were maintained on a diet rich in coconut oil; cellular phospholipids enriched in polyunsaturated fatty acyl groups were produced in animals fed sunflower oil. Insulin receptors were present in the normal cells at 180 000 sites/cell but this fell to 125 000 (p <0.001) in cells enriched in monounsaturated fatty acids and rose to 386 000 (p <0.001) in cells enriched in polyunsaturated fatty acids. The normal cells had affinity constants ( and ) of 0.03 and 0.01 nM⁻¹. The cells enriched in monounsaturated fatty acids had an increase in these affinity constants to 0.06 and 0.03 nM⁻¹ whereas values of 0.01 and 0.005 nM⁻¹ were obtained in the cells enriched in polyunsaturated fatty acids (all comparison p <0.001). Thus, increased unsaturation of plasma membrane phospholipids, produced by dietary manipulations, was associated with an increase in insulin receptor number but a decrease in binding affinity. In contrast, increased saturation of the phospholipids of the plasma membrane was associated with a decrease in receptor number and an increase in affinity. The results can be explained by a model in which the insulin receptor is assumed to be multimeric.     

TyrB26位点改变的人类胰岛素类似物的化学合成与体外活性

摘要：为了研究人类胰岛素B链第26位的酪氨酸对胰岛素和受体之间的结合的影响,包括单独的氨基酸替换或化合物替换的不同的胰岛素类似物被合成,其中化合物替代的类似物的B链C末端都减少了4个氨基酸。在对它们与胰岛素受体的亲和力进行研究中,结果发现它们与胰岛素受体的亲和力没有丢失, HisB26类似物和N-MeHisB26类似物的结合能力与胰岛素相比改变不大,分别是胰岛素的72 %和107 %。N-MeGluB26类似物,AadB26类似物和Phe (4-carboxy) B26类似物的结合能力有很大的提高,分别是130 %, 234 %和160 %。     

胰岛素对βTC-3细胞胰岛素受体表达的作用

目的：观察外源性胰岛素对小鼠胰岛β细胞瘤细胞株βTC-3细胞胰岛素受体表达的影响。方法：采用免疫荧光细胞化学技术结合激光扫描共聚焦显微镜观察高浓度胰岛素（100 IU/ml）刺激不同时间（0 min、30 min、60 min、120 min、240 min）,培养的βTC-3细胞胰岛素受体的表达,用Image pro plus软件对胰岛素受体的荧光强度进行了半定量分析。结果：与0 min比较,胰岛素孵育30 min、60 min、120 min、240 min时胰岛素受体荧光强度均明显下降（P〈0.05）。结论：高浓度胰岛素孵育βTC3细胞后,可明显下调胰岛素受体的表达,这可能是高胰岛素血症导致胰岛素抵抗产生的机制之一。     

Dual microcolumn immunoassay applied to determination of insulin secretion from single islets of Langerhans and insulin in serum

A dual microcolumn immunoassay (DMIA) was developed and applied to determination of insulin in biological samples. The DMIA utilized a protein G capillary column (150 μm I.D.) with covalently attached anti-insulin to selectively capture and concentrate insulins in a sample. Insulins retained in the capillary immunoaffinity column were desorbed and injected onto a reversed-phase capillary column (150 μm I.D.) for further separation from interferences such as cross-reactive antigens and non-specifically adsorbed sample components. Bovine, porcine and rat insulin all cross-reacted with the antibody and could be determined simultaneously. Using a UV absorbance detector, the dual microcolumn system had a detection limit of 10 fmol or 20 pM for 500-μl sample volumes. The DMIA system was used to measure glucose-stimulated insulin secretion from single rat islets of Langerhans. Because of the separation in the second dimension, both rat I and rat II insulin could be independently determined. The system was also evaluated for determination of insulin in serum. Using microcolumns instead of conventional HPLC columns resulted in several advantages including use of less chromatographic material and improved mass detection limit.     

水杨酸钠对胰岛素抵抗大鼠胰岛素受体底物-1的影响

目的探讨抗炎药水杨酸钠对胰岛素抵抗大鼠胰岛素敏感性的影响及其作用机制。方法分别给大鼠静脉输注脂肪乳+肝素,脂肪乳+肝素+水杨酸钠和生理盐水7 h,并在输注的最后2 h,行清醒状态高胰岛素-正血糖钳夹试验,测定血浆葡萄糖、游离脂肪酸(FFA)、胰岛素和C-肽水平,检测肝脏、肌肉中胰岛素受体底物-1(IRS-1)及307位丝氨酸磷酸化的IRS-1表达。结果输注脂肪乳大鼠葡萄糖输注率(GIR)是输注生理盐水大鼠的45%,水杨酸钠可使GIR提高1.3倍(P0.01)。脂肪乳输注组大鼠肝脏及肌肉中307位丝氨酸磷酸化的IRS-1分别为生理盐水输注组大鼠的3倍和3.8倍(P0.001),输注水杨酸钠,肝脏、肌肉307位丝氨酸磷酸化的IRS-1下降45%、20%(P0.05)。结论 FFA增高引起肝脏及肌肉中307位丝氨酸磷酸化的IRS-1水平增高,可能是导致胰岛素抵抗发生的机制之一,应用水杨酸钠,大鼠肝脏及肌肉组织中IRS-1丝氨酸磷酸化水平下降,胰岛素抵抗改善。抗炎药物水杨酸钠可能通过抑制FFA引起的IRS-1丝氨酸磷酸化,而发挥改善胰岛素抵抗的作用。     

Insulin Binding in Four Regions of the Developing Rat Brain

Specific insulin binding has been demonstrated in partially purified membranes prepared from four regions of the developing rat brain. Insulin binding to brain membranes demonstrated kinetics and hormonal specificity that were quite similar to those reported for traditional insulin target tissues (e.g., liver and adipose tissue), and binding was significantly correlated with receptor concentration. Binding in the olfactory bulbs, cerebrum, cerebellum, and hypothalamus all reached highest values at 15 days of postnatal life, with the olfactory bulbs generally showing the greatest binding at all ages studied. A temporal relationship was found between insulin binding to brain membranes in the postnatal rat and plasma membrane protein synthesis, especially in the cerebellum and olfactory bulbs.     

Labeling of insulin with non-radioactive I and application to incorporation of radioactive I for use in receptor-binding experiments by high-performance liquid chromatography

Conditions for the labeling of insulin with radioactive iodine isotopes were investigated by means of incorporation of non-radioactive ¹²⁷I into the peptide. Either the chloramine-T (CT) or lactoperoxidase-hydrogen peroxide (LPO) technique was applied and reversed-phase high-performance liquid chromatography (RP-HPLC) was used for analysis of the reaction products. The LPO method provided the ¹²⁷I-labeled peptide within 15–30 min, whereas the CT alternative yielded the labeled substrate even within 15 s. However, the latter reaction can only be controlled in a reproducible manner with difficulty and undesirad side-reactions became increasingly prominent when t a few seconds. In another experiment, the LPO technique was applied for radiolabeling insulin with ¹²⁵I. The product was first purified by size-exclusion chromatography (SEC) and then subjected to RP-HPLC. SEC yielded two peaks. The smaller one, which eluted at a slightly higher K_d value (accounting for about 14% of total radioactivity) predominantly consisted of material eluting at the column's void volume under the conditions of RP-HPLC, whereas the main SEC fraction (accounting for about 86% of total radioactivity) yielded a single peak, as shown by HPLC. The radioactive material attributable to the main SEC fraction revealed the expected receptor-binding properties, as evidenced by displacement experiments with non-radioactive insulin, as well as the action of tetradecanoyl phorbol acetate on the binding characteristics and thus indicating formation of a labeled hormone retaining biological activity.     

Physiological levels of insulin and IGF-1 synergistically enhance the differentiation of mesenteric adipocytes

Visceral adipose tissue, particularly mesenteric adipose tissue, is important in the pathogenesis of metabolic syndrome. Here, we present a physiologically relevant differentiation system of rat mesenteric-stromal vascular cells (mSVC) to mesenteric-visceral adipocytes (mVAC). We optimized the insulin concentration at levels comparable to those in vivo ( approximately 0.85 ng/ml) by including physiological concentrations of IGF-1. We found that the insulin-like growth factor (IGF-1) and insulin worked synergistically, since IGF-1 alone could induce CCAAT/enhancer binding protein alpha (C/EBPalpha) and adipocyte lipid binding protein (aP2) mRNA expression but not lipid droplet accumulation associated with maturation. Using real-time PCR analyses on 180 adipocyte-related genes, we identified a dramatic effect by IGF-1 plus insulin. We also demonstrated the state of insulin resistance at pathologically high insulin concentrations. This culture system will contribute to understanding the physiological differentiation process and the patho/physiology of mVAC.