IA-2 (also known as islet cell antigen ICA-512) and IA-2β (also known as phogrin, phosphatase homologue in granules of insulinoma) are major autoantigens in insulin-dependent diabetes mellitus (IDDM). Autoantibodies against both proteins are expressed years before clinical onset, and they become predictive markers for high-risk subjects. However, the role of these genes in the IDDM pathogenesis has been reported fairly negative by recent studies. IA-2 and IA-2β are type I transmembrane proteins that possess one inactive protein-tyrosine phosphatase (PTP) domain in the cytoplasmic region, and act as one of the constituents of regulated secretory pathways in various neuroendocrine cell types including pancreatic β-cells. Existence of IA-2 homologues in different species suggests a fundamental role in neuroendocrine function. Studies of knockout animals have shown their involvement in maintaining hormone content, however, their specific steps in the secretory pathway IA-2 functions as well as their molecular mechanisms in the hormone content regulation are still unknown. More recent studies have suggested a novel function showing that they contribute to pancreatic β-cell growth. This review attempts to show the possible biological functions of IA-2 family, focusing on their expression and localization in the neuroendocrine cells.
Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant hereditary disease. Primary hyperparathyroidism is known to occur at an early age in MEN1 patients. In MEN1 patients, special care regarding not only surgery for hyperparathyroidism but also other MEN1-related tumors is required. Between 1998 and 2007, 482 patients, including 16 whose hyperparathyroidism was discovered by family screening for MEN1, underwent surgical therapy for primary hyperparathyroidism at our institution. We recommended MEN1 gene analysis for patients having one of the following clinicopathological features: 1) age younger than 30 years old; 2) enlargement of multiple glands; 3) coexistence or presence of past history of MEN1-related tumors; or 4) family history of hyperparathyroidism or MEN1-related tumors. Sixty patients had at least one of the above features and were recommended for genetic analysis. Thirty-nine of these patients consented to undergo MEN1 genetic analysis and 16 (41%) showed MEN1 mutation. Pathological examination confirmed multiglandular parathyroid hyperplasia in 15 cases. Subject to this strategy, MEN1 index patients in Japan could be detected efficiently and selected for appropriate therapies for hyperparathyroidism and MEN1-related tumors.
A 16-week, multicenter, randomized, double blind, parallel-group study was performed to examine whether additional administration of mitiglinide improves glycemic control in Japanese type 2 diabetic patients who are insufficiently controlled by pioglitazone monotherapy. Japanese adult type 2 diabetic patients were at first treated with diet plus pioglitazone 15−30 mg/day for 4 weeks then randomized to receive additional mitiglinide 5 or 10 mg or placebo tid for a further 16 weeks. In all, 381 patients were randomized. At final evaluation, glycated hemoglobin (HbA1C) was reduced by (mean ± SD) −0.02 ± 0.60% in the pioglitazone monotherapy group and by −0.45 ± 0.77% and −0.67 ± 0.59% in the mitiglinide 5 and 10 mg combination groups, respectively (both p<0.001 vs. pioglitazone monotherapy group). The percentage of patients who achieved HbA1C targets was significantly (p<0.001) higher in the mitiglinide combination groups than in the pioglitazone monotherapy group. Significant improvements in fasting plasma glucose and postprandial plasma glucose were noted in the mitiglinide combination groups versus the pioglitazone monotherapy group. No increase in adverse events was noted when mitiglinide was administered concomitantly with pioglitazone monotherapy. Hypoglycemic adverse events were infrequently and similarly observed in all three groups. Body weight gain and edema presented no clinical problem. HbA1C was significantly improved in the mitiglinide combination groups compared with the pioglitazone monotherapy group, and significantly more patients achieved HbA1C targets. Therefore mitiglinide effectively improves glycemic control in type 2 diabetic patients who are inadequately controlled by pioglitazone monotherapy.
SST-VEDI-1(VEDI-1) is a new synthetic compound that is synthesized from tryptamine, and has structural similarity to the SSH-BM family of compounds. However, the biological effects of VEDI-1 have yet to be well characterized. A recent report has demonstrated that SSH-BM-type compounds can stimulate osteoblast activity in cultured scales of goldfish. In this study, we examined the effects of VEDI-1 on osteoblastic differentiation as well as its effects on apoptosis, which is known to be closely related to osteoblastic differentiation. We found that VEDI-1 enhanced the formation of mineralized nodules in rat osteoblast cell lines, including ROS17/2.8 cells, and in mouse pre-osteoblast cell lines, including MC3T3-E1 cells, in a dose dependent manner, which was accompanied by increased expression of late osteoblast markers, bone sialoprotein (BSP) and osteocalcin (OC). Furthermore, VEDI-I inhibited apoptotic cell death and regulated the expression of proteins in the Bcl-2 family. These results suggest that VEDI-1 may facilitate late differentiation of osteoblasts and may have an inhibitory effect on apoptosis.
Epidemiologic studies have shown that in utero malnutrition is a risk factor for adult cardiovascular disease (CVD). Recently, we reported a mouse animal model of 30% maternal caloric reduction, in which offspring showed a significant increase in systolic blood pressure (SBP) as well as in cardiac remodeling-associated morphological parameters such as cardiac enlargement and coronary perivascular fibrosis in adulthood. Using a similar animal model, we here demonstrated that an increased level of protein consumption during an undernourished pregnancy (high-protein diet; HPD) corrected for the development of CVD risk factors found in fetal undernourishment with less protein consumption (standardprotein diet; SPD). In contrast, maternal ad libitum feeding with HPD resulted in significantly elevated SBP and cardiac enlargement in offspring at 16 wks. Appropriate maternal protein ingestion might partly protect against the development of CVD risk factors in offspring.
Endothelial dysfunction is considered to be an early event in the development of atherosclerosis. The present study was undertaken to evaluate endothelial function and biochemical markers in type 2 diabetes mellitus (T2DM) patients before and after treatment with or without pioglitazone (PIO). Forty-one T2DM patients without macroangiopathy were randomized to treatment with (n=20) or without (control, n=21) PIO for 12 weeks. Endothelial function was assessed by flow-mediated vasodilation (FMD) using a high-resolution ultrasound method before and after treatment. After treatment, HbA1c levels equally decreased in both groups, but PIO-treated group had significantly increased high-density lipoprotein cholesterol (HDL-C) levels, and decreased triglyceride, fasting insulin levels and HOMA-R. After treatment, increases in %FMD, plasma HDL-C and adiponectin (APN) levels were significantly greater in PIO-treated group than those in control group. Changes of %FMD showed significant positive correlations with those of plasma APN and HDL-C levels. In conclusion, the present study showed that treatment of T2DM improved endothelial function with greater increases in %FMD, APN and HDL-C levels in PIO-treated group than those in control group, suggesting the beneficial effect of PIO on endothelial function in T2DM.
Reactive oxygen species (ROS) are induced under diabetic conditions and are likely associated with the development of type 2 diabetes. It is also known that ROS production is facilitated in the presence of copper ion through the Fenton reaction. The aim of this study was to examine the involvement of copper ion in the pathogenesis of type 2 diabetes and to evaluate the potential usefulness of a copper chelating agent for the treatment of type 2 diabetes. First, both serum copper ion and ROS levels in diabetic C57BL/KsJ-db/db mice were significantly higher compared to those in nondiabetic mice. Second, we treated diabetic db/db mice with a copper chelating agent tetrathiomolybdate and examined the effects on the development of type 2 diabetes. As the results, both serum copper ion and ROS levels were significantly decreased by the treatment, which were equivalent to those in non-diabetic mice. Consequently, the treatment with a copper chelating agent reduced insulin resistance and ameliorated glucose intolerance in diabetic db/db mice. In addition, serum triglyceride levels were also decreased by the treatment. In conclusion, our present results suggest that copper ion is involved in the development of type 2 diabetes and thereby a potential therapeutic target for diabetes.
p27kip1 is a well known negative regulator of cell cycle progression. Jab1 directly binds to p27kip1 and induces nuclear export and subsequent degradation. Recent studies have shown that overexpression of Jab1 and reduced expression of p27kip1 are associated with advanced tumor stage and poor prognosis in several human cancers. Here, we evaluated 50 papillary thyroid carcinomas (PTC) and adjacent normal thyroid tissue samples by immunohistochemistry for Jab1 and p27kip1 to elucidate expression levels and subcellular localization. Expression of Jab1 was markedly increased and that of p27kip1 was reduced in the tumors compared with paired normal samples. Jab1 expression was inversely related to p27kip1 expression. Jab1 was especially overexpressed within the invasive region compared to center of the tumors. Among clinicopathologic parameters, only tumor size was related with Jab1 (positively) and p27kip1 expression (negatively) in the invasive region of the tumors. Both Jab1 and p27kip1 were found predominantly in the cytoplasm of the tumor cells from the invasive regions compared to center of the tumors. The Ki-67 proliferative index was higher in the invasive region than in center of the tumors. A much stronger correlation with the Ki-67 index was noted when both Jab1 and p27kip1 were simultaneously localized in the cytoplasm than when either Jab1 or p27kip1 was localized in the cytoplasm alone. These data suggest that in addition to overexpression of Jab1 and reduced expression of p27kip1, cytoplasmic localization of Jab1 and p27kip1 are associated with increased cancer cell proliferation and might be related to the invasiveness of PTC.
A 73-year-old woman was admitted to our department for treatment of diabetes (plasma glucose 289 mg/dl, HbA1C 7.1%, and glycated albumin 34.9%). She displayed the signs and symptoms of glucagonoma syndrome, including necrolytic migratory erythema (NME), low aminoacidemia, and a marked increase of the serum glucagon level (4,940 pg/ ml). Thus, we suspected a glucagonoma causing secondary diabetes. However, we could not detect any mass in the pancreas or the gastrointestinal tract, and only found a liver lesion resembling a hemangioma. Her NME improved markedly after intravenous infusion of amino acids, and her plasma glucose was controlled reasonably well by intensive insulin therapy. However, her general condition deteriorated and she died on day 57 after hospitalization. At autopsy, the only tumor detected was the liver mass. This was a large solid tumor (8×6×5 cm) with a pattern of white and dark brown stripes located in the left lobe, while two white nodules were also found in the right lobe. Based on the histopathological and immunohistochemical findings, the liver lesion was shown to be a malignant glucagonoma with intrahepatic metastases. Since primary malignant hepatic glucagonoma has not been reported before, we present this extremely rare case of primary malignant glucagonoma of the liver.
In pediatric and adolescent patients, the most common causes for a thickened pituitary stalk with central diabetes insipidus are germ cell tumors, lymphocytic infundibuloneurohypophysitis (LIN), and Langerhans cell histiocytosis (LCH). We describe here a 13-year-old girl who had an abrupt onset of polyuria and polydipsia. Magnetic resonance imaging of the brain revealed thickening of the pituitary stalk, and loss of the physiological hyperintense signal of the posterior pituitary gland. Based on a histopathology, she was diagnosed as having LCH. Another LCH lesion was not detected. The prognoses for LCH patients with single-system and single-site are generally good so we decided on only simple observation. The lesion spontaneously regressed 3 months later, resembling a typical self-limiting course of LIN. In conclusion, the present case suggests that 1) radiological differential diagnosis between LIN and LCH is so difficult that histological confirmation is crucial for correct diagnosis, 2) some past cases of histologically-unconfirmed LIN can include LCH, 3) solitary neurohypophyseal LCH can shrink spontaneously up to near remission level.