Neuroendocrine factors regulating blood glucose, plasma FFA and insulin in the development of obesity

A number of neurotransmitters and neuropeptides in the hypothalamus play a role in the control of food intake, metabolism, and body weight. Particularly, noradrenergic mechanisms in several areas of the hypothalamus are involved. Control of peripheral metabolism by the hypothalamus is achieved via autonomic modulation of the function of hepatocytes, adipocytes, and the endocrine cells in the islets of Langerhans. The autonomic control mechanisms ultimately lead to an appropriate shaping of blood glucose, plasma FFA, and insulin profiles to guarantee an adequate flow of nutrients under different physiological situations. Peripheral insulin and glucose can penetrate into the brain where they might affect the function of those brain structures involved in control of food intake, metabolism, and body weight.     

大鼠胰岛细胞与睾丸支持细胞联合微囊化的体外功能研究

将大鼠胰岛细胞和Sertoli细胞联合微囊化后培养11天，胰岛细胞和Sertoli联合微囊化组的胰岛功能明显好于胰岛Sertoli细胞分别微囊化的共同培养组及胰岛单独微囊组（P〈0．05）。     

Quantification of Basal and Stimulated ROS Levels as Predictors of Islet Potency and Function

We have developed a luminol-based assay using intact islets, which allows for quantification of reactive oxygen species (ROS). In addition, an index capable of characterizing metabolic and mitochondrial integrity prior to transplantation was created based on the capacity of islets to respond to high glucose and rotenone (mitochondrial respiratory chain complex I inhibitor) by production of ROS. To validate this assay, lipid peroxidation and antioxidative defense capacity were evaluated by detection of malondialdehyde (MDA) levels and glutathione peroxidase activity (GPx), respectively. Also, flow cytometric analyses of ROS (dihydroethidine), apoptosis (Annexin V, active caspases), necrosis (Topro3), and mitochondrial membrane potential (JC-1) were done in parallel to correlate with changes in luminol-measured ROS. ATP/ADP ratios were quantified by HPLC and the predictive value of ROS measurement on islet functional potency was correlated with capacity to reverse diabetes in a streptozotocin-induced diabetic NOD.scid mouse model as well as in human transplant recipients. Our data demonstrate that levels of ROS in islets correlate with the percentage of apoptotic cells and their functional potency in vivo. The ROS indices following glucose and rotenone exposure are indicative of metabolic potency and mitochondrial integrity and can be used as surrogate markers to evaluate the quality of islets prior to transplantation.     

非功能性胰岛细胞瘤16例临床分析

目的探讨非功能性胰岛细胞瘤的诊断和治疗方法。方法对近16年间收治的非功能性胰岛细胞瘤16例临床资料回顾性分析。其中位于胰头部4例,胰体尾部12例,瘤体长径平均12cm。结果行肿瘤摘除术6例,胰十二指肠切除术3例,行包括肿瘤在内的远端胰腺及脾脏切除3例,保留脾脏的胰体尾切除术3例,因肿瘤广泛侵浸未能切除1例。治愈性切除率为93.75%(15/16),全组无手术死亡。随访资料显示:11例良性肿瘤患者全部存活,已2～16年。5例恶性肿瘤患者中,1例因肿瘤广泛侵犯未能切除者,术后5个月死于多器官衰竭;1例胰体尾切除并左肝切除者存活2年;胰十二肠切除者2例,分别存活1年和6年,胰体尾切除加脾切除1例已存活12年8个月。结论钡餐,B超,CT,MRI,以及ERCP对该病有诊断价值,手术切除是治疗非功能性胰岛细胞瘤的主要方法,效果良好。     

Nitric oxide is not involved in the initiation of insulin secretion from rat islets of Langerhans

Summary The involvement of nitric oxide as an intracellular messenger in the control of insulin secretion from pancreatic Beta cells was studied in rat islets of Langerhans by measuring: (i) nitric oxide generation in response to physiological insulin secretagogues; (ii) the effects of inhibitors of nitric oxide synthesis on insulin secretory responses to physiological secretagogues, and on insulin synthesis; (iii) changes in islet cyclic guanosine monophosphate in response to secretagogues; (iv) the effects of exogenous cyclic guanosine monophosphate and dibutyryl cyclic guanosine monophosphate on insulin secretion from electrically permeabilised islets and from intact islets, respectively. These studies produced no evidence that nitric oxide generation is required for the initiation of insulin secretion by common secretagogues. However, the results of our experiments suggest that the generation of nitric oxide may be involved in long-term, glucose-dependent increases in cyclic guanosine monophosphate content of islet cells, although the physiological relevance of these changes requires further investigation.     

Modified Two-Layer Preservation Method (M-Kyoto/PFC) Improves Islet Yields in Islet Isolation

Islet allotransplantation can achieve insulin independence in patients with type I diabetes. Recent reports show that the two-layer method (TLM), which employs oxygenated perfluorochemical (PFC) and UW solution, is superior to simple cold storage in UW for pancreas preservation in islet transplantation. However, UW solution has several disadvantages, including the inhibition of Liberase activity. In this study, we investigated the features of a new solution, designated M-Kyoto solution. M-Kyoto solution contains trehalose and ulinastatin as distinct components. Trehalose has a cytoprotective effect against stress, and ulinastatin inhibits trypsin. In porcine islet isolation, islet yield was significantly higher in the M-Kyoto/PFC group compared with the UW/PFC group. There was no significant difference in ATP content in the pancreas between the two groups, suggesting that different islet yields are not due to their differences as energy sources. Compared with UW solution, M-Kyoto solution significantly inhibited trypsin activity in the digestion step; moreover, M-Kyoto solution inhibited collagenase digestion less than UW solution. In conclusion, the advantages of M-Kyoto solution are trypsin inhibition and less collagenase inhibition. Based on these data, we now use M-Kyoto solution for clinical islet transplantation from nonheart-beating donor pancreata.     

Fas配体阳性睾丸细胞对共移植的胰岛细胞存活起全身和/或局部的免疫豁免作用

目的探讨Fas配体阳性睾丸细胞对共移植的胰岛细胞存活起全身和/或局部的免疫豁免作用。方法将同种大鼠胰岛细胞与不同数量的睾丸细胞同侧或两侧共移植于糖尿病受体肾包膜下,观察移植物功能和存活情况,以及移植物内淋巴细胞凋亡。结果单纯移植胰岛组(对照组)平均存活期为(4.6±1.1)天。睾丸细胞和胰岛细胞同侧共移植时,当睾丸细胞数为1×106(A组)时,胰岛细胞平均存活期为(23.8±4.6)天;睾丸细胞数增至1×107时(B组),胰岛细胞存活期大于(57.5±4.0)天,均较对照组明显延长(P<0.01)。两侧共移植时,当睾丸细胞数为1×105(C组),胰岛细胞平均存活期为(6.0±1.4)天,与对照组相似(P>0.05);睾丸细胞数增至1×106(D组),胰岛细胞存活期(11.5±3.1)天较对照组或C组延长(P<0.01);睾丸细胞数增至1×107(E组)时,胰岛细胞存活期(31.2±15.9)天延长更加明显(P<0.01)。相同剂量的睾丸细胞与胰岛细胞分别同侧和两侧共移植时发生移植排斥反应各自的病理表现是不同的,前者移植物内有淋巴细胞浸润,部分胰岛玻璃样变,抗胰岛素抗体染色仅见少量阳性细胞,而后者胰岛细胞移植物内有大量的淋巴细胞和少量的中性粒细胞浸润,抗胰岛素抗体阳性细胞较少,未见胰岛玻璃样变。原位细胞凋亡检测发现同侧共移植后的移植物与肾实质交界处有淋巴细胞凋亡。电镜检查发现胰岛移植物存活超过60d的标本可见大量存活的胰岛细胞团和睾丸Sertoli细胞,有散在的凋亡淋巴细胞。结论睾丸细胞与同种胰岛细胞移植后不仅可诱导局部免疫豁免,而且也具有一定的全身免疫保护作用,但较局部免疫豁免作用弱;这些作用可延长移植物的存活期,并具有剂量依赖性。     

Duct-Islet Cell Tumor of the Pancreas. A Case Report with Immunohistochemical and Electron Microscopic Findings

A case of pancreatic tumor with features of both duct and islet cell components was found incidentally at autopsy in a 76 year old male who had died of intrahepatic cholan-giocarcinoma. The tumor, measuring about l.0cm in diameter, was located in the pancreatic tail. The tumor was composed of two distinct cell populations, islet cells and duct cells. Immunocytochemically, nearly all of the former cells were positive for insulin but negative for cytokeratin, carcinoembryonic antigen (CEA) and mucin, while the latter were positive for cytokeratin, CEA and mucin but negative for insulin. Additionally, a majority of the tumor cells that had formed islet-like structures were positive for neuron specific enolase (NSE), whereas NSE-positive cells were found only rarely in duct components. Electron microscopy confirmed the presence of two cell populations. Simultaneous occurrence of duct and islet cell components in a single pancreatic tumor indicates an intimate histogenetic relationship between pancreatic endocrine and duct cells. Acta Pathol Jpn 39: 328 335, 1989.