Toshimitsu Okeda

Vascular cell adhesion molecule-l expression in the renal interstitium of diabetic KKAy mice

To investigate the mechanism of interstitial inflammation in diabetic nephropathy, we used spontaneously diabetic KKAy mice. Twelve KKAy mice were divided into two groups; six mice were fed standard mouse chow ad libitum and six mice were placed on a diet (i.e. they received the same amount of chow as six control C57BL mice). Diabetic KKAy mice developed hypercholesterolemia and albuminuria. Animals were killed at 16 weeks of age and renal tissues were immunostained for vascular cell adhesion molecule-1 (VCAM-1). In diabetic KKAy mice, the renal interstitium was infiltrated by monocytes, lymphocytes, plasma cells, and other cells. The walls of venules near the infiltrating cells were more intensely stained for VCAM-1 when compared with other sites. In contrast, the VCAM-1 staining of arterioles and peritubular capillaries was not significantly increased. There was weak VCAM-1 staining of the infiltrating cells, including lymphocytes, monocytes, and other cells. Electron microscopy demonstrated immunolabeling for VCAM-1 on the cell surface and in the cytoplasm of both infiltrating cells and vascular endothelial cells. In KKAy mice placed on a diet, there was less staining for VCAM-1 and cellular infiltration was also decreased. Thus, increased expression of VCAM-1 by the endothelial cells of venules and VCAM-1 expression by infiltrating cells were demonstrated in the interstitium of kidneys from diabetic mice. These results suggest that increased expression of VCAM-1 by endothelial cells and infiltrating cells contributes to interstitial inflammation in diabetic nephropathy.

Genome-wide linkage analysis of type 2 diabetes mellitus reconfirms the susceptibility locus on 11p13–p12 in Japanese

AbstractType 2 diabetes mellitus is a heterogeneous disorder, and the development of type 2 diabetes mellitus is associated with both insulin secretion defect and insulin resistance. The primary metabolic defect leading to type 2 diabetes mellitus has been thought to be varied among populations, especially in Japanese and Caucasians. Here, we have done the genome-wide scan for type 2 diabetes mellitus using 102 affected Japanese sib-pairs to identify the genetic factors predisposing to type 2 diabetes mellitus. Nonparametric linkage analysis showed one suggestive evidence for linkage to 11p13-p12 [D11S905: two-point maximum LOD score (MLS) of 2.89 and multipoint MLS of 2.32] and one nominally significant evidence for linkage to 6q15-q16 (D6S462: two-point MLS of 2.02). Interestingly, the 11p13-p12 region was reported to be a susceptibility locus for Japanese type 2 diabetes mellitus with suggestive evidence of linkage, and D11S905 was within 5 cM to D11S935 with the highest MLS in the previous linkage analysis reported. The only overlapped susceptibility region with suggestive evidence of linkage for Japanese type 2 diabetes mellitus was D11S935-D11S905 among the three reports including this study. These results taken together suggest that a susceptibility gene for type 2 diabetes mellitus in Japanese will reside in 11p13-p12.

Microencapsulation of pancreatic islets: A technique and its application to culture and transplantation

Hamster pancreatic islets were encapsulated by a biocompatible membrane composed of the molecular sequence of alginate-polylysine-alginate. The encapsulated islets released insulin into the culture medium in response to secretagogues in short-term incubation. In long-term culture, the encapsulated islets maintained their insulin-releasing capacity for 28 days at a level similar to that of the unencapsulated islets. No overgrowth of fibroblastic cells was observed inside the capsule even after 70 days of culture. Further, the encapsulated hamster islets were xenotransplanted to streptozotocin-induced diabetic rats intraperitoneally. Some of the encapsulated islets, which were recovered from a recipient 27 days after transplantation, were found to be viable, although prolonged normalization of fasting plasma glucose levels of the recipients could not been achieved. On the contrary, the unencapsulated islets were replaced by massive connective tissue elements and insulin-positive B cells were hardly detected within the grafts 22 days after transplantation. The results of this study seem to confirm the potential of the application of the encapsulating technique to primary culture of parenchymal cells and to transplantation of pancreatic islets.

TYK2 Promoter Variant and Diabetes Mellitus in the Japanese

Background Recently, natural mutation of Tyrosine kinase 2 (Tyk2) gene has been shown to determine susceptibility to murine virus-induced diabetes. In addition, a previous human genome-wide study suggested the type 1 diabetes (T1D) susceptibility region to be 19p13, where the human TYK2 gene is located (19p13.2). Methods Polymorphisms of TYK2 gene at the promoter region and exons were studied among 331 healthy controls, and 302 patients with T1D and 314 with type 2 diabetes (T2D) in the Japanese. Findings A TYK2 promoter haplotype with multiple genetic polymorphisms, which are in complete linkage disequilibrium, named TYK2 promoter variant, presenting decreased promoter activity, is associated with an increased risk of not only T1D (odds ratio (OR), 2.4; 95% confidence interval (CI), 1.2 to 4.6; P = 0.01), but also T2D (OR, 2.1; 95% CI, 1.1 to 4.1; P = 0.03). The risk is high in patients with T1D associated with flu-like syndrome at diabetes onset and also those without anti-glutamic acid decarboxylase autoantibody. Interpretation The TYK2 promoter variant is associated with an overall risk for diabetes, serving a good candidate as a virus-induced diabetes susceptibility gene in humans. Funding Ministry of Education, Culture, Sports, Science and Technology and of Health, Labor and Welfare of Japan.

Plasminogen Activator Inhibitor—1 in Nonobese Subjects with Non-Insulin-Dependent Diabetes Mellitus

Abstract Elevated plasma levels of plasminogen activator inhibitor-1 (PAI-1) have been shown to be a risk factor for the development of vascular complications in obese and hyperinsulinemic non-insulin-dependent diabetes (NIDDM) patients. To clarify whether PAI-1 also plays an essential role in the development of such complications in NIDDM patients without obesity or hyperinsulinemia, PAI-1 was analyzed in relation to blood pressure, fasting plasma levels of glucose (FPG), hemoglobin A1c (HbA1c), immunoreactive insulin (F-IRI), C-peptide (CPR), total cholesterol (TC), triglyceride (TGL), and HDL-cholesterol (HDL-C) in 77 NIDDM patients and 10 healthy control subjects. The NIDDM patients were not obese (body mass index [BMI]: <26 kg/m2) or hyperinsulinemic, and BMI in the controls was between 19 and 24 kg/m2. In addition, parameters of insulin secretion reserve, including ΣIRI, insulinogenic index, and CPR at 5 min after glucagon loading, were evaluated simultaneously. Plasma levels of PAI-1 were higher in the NIDDM group (9.3 ± 0.9 ng/ml) than in the controls (4.3 ± 0.7 ng/ml; P < 0.01). Levels of FPG and HbAic were also elevated in the NIDDM group (P < 0.05 for each), but F-IRI did not differ between the two groups. However, multiple regression analysis revealed no significant correlation in the NIDDM between PAI-1 and F-IRI or the parameters of insulin secretion reserve. Regardless of the presence or absence of vascular complications, PAI-1 did not vary significantly in the NIDDM. These findings suggest that the effects of PAI-1 on the development of diabetic complications in NIDDM patients may not proceed in the same way in those with versus those without obesity or hyperinsulinemia, because no correlation was found between PAI-1 and insulin secretion reserve, while plasma levels of PAI-1 were higher in the NIDDM group than in the controls.

The Impact of a Color-Classified HbA1c Graph for Self-Monitoring and Self-Adjustment of Long-Term Glycemic Control

D uring the previous 4 8 wk (1,2), accumulating evidence has revealed that long-term glycemic control as expressed by HbAlc, the value of which is closely related to the mean level of blood glucose, is closely associated with the progression of diabetic complications (3-5). Thus, HbAlc can serve as the most important marker for long-term glycemic control. Some difficulties arise when teaching patients about the meaning of HbAlc and the relationship between HbAlc levels and the progression of diabetic complications. Therefore, we attempted to introduce a color-classified HbAlc graph in which the HbAlc level was color-classified according to the relative risk of the HbAlc level on the progression of complications. In this study, it soon became clear that the HbAlc graph allowed patients to visualize their HbAlc levels and, therefore, better understand their conditions. Thus, they were also encouraged to take some positive actions to lower their levels. From 1989 to 1990, 108 Japanese NIDDM patients were analyzed. They completed a 6-mo follow-up before and after the graph was given without any alteration of the treatment regimen. The NIDDM patients included 48 males and 60 females with a mean age of 59.3 ± 10.2 yr, a mean diabetes duration of 8.5 ± 6.9 yr, and a mean BMI of 23.0 ± 0.3 kg/m. All patients had previously received the usual diabetes education program, which included an educational program to show the meaning and significance of HbAlc. HbAlc was assayed by HPLC on a monthly basis for 1 yr. The normal range of this assay system is 4.5-6.0%. The mean of every 3 mo was calculated and compared both before and after the graph was given. The color-classified HbAlc graph was color-grouped according to the HbAlc level, which demonstrates the relative risk of long-term diabetic complications with an appropriate color image of the relative risk: HbAlc <6%, green, normal; 6-7%, yellow-green, fair; 7-8%, yellow, risky; 8-10%, red, poor; and >10%, purple, critical (Fig. 1). A monthly recording of HbAlc for 1 yr was possible, and monthly variations of HbAlc levels can be seen at a glance. One month after the graph was given, a patient questionnaire was distributed to examine the psychological and behavioral effect of the graph and to determine whether the graph contributed to an in-

Evidence for secretion of 7B2 by A- and B-cells of hamster pancreatic islets

7B2 is a neuroendocrine protein, and in the pancreatic islets the presence of 7B2 in A- and B-cells was immunohistochemically demonstrated. In order to examine 7B2 secretion by A- and B-cells of pancreatic islets, we prepared isolated hamster pancreatic islet cells as well as an A-cell-rich culture, and studied 7B2 secretion under certain stimulations. 7B2 was secreted by isolated hamster pancreatic islet cells. This secretion was stimulated by theophylline and arginine, but glucose had a weak effect on the 7B2 secretion. Such a response of 7B2 to the stimulations was different from that of insulin or glucagon. 7B2 secretion was also noted in the A-cell-rich culture. These results suggest that 7B2 is secreted by both A- and B-cells of the hamster pancreatic islets and its secretion is regulated under certain conditions.