The output and time-course of insulin release from pancreatic beta-cells are elegantly controlled. The secretory process comprises pre-exocytotic stages, exocytosis and post-exocytotic stages. The small GTPase Rab27a is known to regulate pre-exocytotic stages that determine the size of the readily-releasable pool of insulin granules. GTP-Rab27a and its specific effectors are responsible for this process like other GTPases. Recently, we searched for Rab27a-interacting proteins and identified coronin 3. Unexpectedly, coronin 3 only bound GDP-Rab27a and this interaction regulated post-exocytotic stages via reorganization of the actin cytoskeleton. Since glucose converts Rab27a from the GTP- to GDP-bound form, we suggested that Rab27a plays a crucial role in stimulus-endocytosis coupling in pancreatic beta-cells, and that this is the key molecule for membrane recycling of insulin granules. In this review, we provide an overview of the roles of Rab27a and its GTP- and GDP-dependent effectors in the insulin secretory pathway of pancreatic beta-cells.

View full abstract

Thyroid MALT lymphoma is an extremely rare malignancy believed to arise against a background of Hashimoto’s thyroiditis. Rituximab is a monoclonal antibody directed against B cell specific antigen CD20. Recently, there have been reports that rituximab is effective for autoimmune thyroid diseases such as Graves’ disease as well as for treatment of B cell malignant lymphoma. We present the changes in thyroid autoantibodies in Hashimoto’s thyroiditis after rituximab administration for 3 cases of thyroid MALT lymphoma. Case 1 had been taking levothyroxine and was diagnosed with thyroid MALT lymphoma. She was treated with rituximab monotherapy, and her thyroid enlargement improved. Anti-thyroid peroxidase antibody (TPOAb) turned negative after rituximab monotherapy, and TSH levels decreased with the same levothyroxine dosage. Case 2 was diagnosed with recurrent thyroid MALT lymphoma after chemotherapy (CHOP). He suffered from leg sensory disturbance because of vincristine sulfate. The patient was treated with rituximab. TPOAb decreased, but did not turn negative. TSH levels were within normal range during the disease course, but TSH levels were low in comparison with before rituximab therapy. Case 3 was diagnosed with thyroid MALT lymphoma after radiation therapy on the neck for laryngeal cancer. Thyroid enlargement improved after rituximab monotherapy, and thyroid autoantibody levels decreased. TSH increased transiently after radiation therapy, but TSH decreased gradually without levothyroxine after rituximab monotherapy. We report 3 cases in which thyroid autoantibody levels in Hashimoto’s thyroiditis decreased after rituximab monotherapy for thyroid MALT lymphoma, but it is controversial whether thyroid dysfunction due to Hashimoto’s thyroiditis is restored.

View full abstract

Since there is increasing evidence that postprandial hyperglycemia is a risk factor for the development of macrovascular complications, it is important to predict postprandial hyperglycemia in the early stages of glucose intolerance, and routine medical checkups provide a good opportunity to do so. The aim of this study was to evaluate the usability of 1,5-anhydroglucitol (1,5-AG) in routine medical checkups. The subjects were 77 Japanese men who participated in a routine medical checkup. First, we performed 75 g oral glucose tolerance tests (OGTTs), and examined the changes in glucose and 1,5-AG levels measured at 0, 30, 60, 90, 120, and 180 minutes (min). 1,5-AG levels did not significantly change until 90 min after the glucose load. Second, a linear regression analysis showed an inverse correlation between the 2-hour post-challenge glucose (2h-PG) and baseline 1,5-AG levels during the OGTT (P = 0.001, r² = 0.13), and the correlation was still significant after adjustment for age (2h-PG = 170 + 0.83 × (age in years) - 3.23 × (1,5-AG), P = 0.002, adjusted r² = 0.12). Finally, to investigate the test characteristics of 1,5-AG levels as a predictor of a 2h-PG level≥200 mg/dL, we plotted a receiver operating characteristic (ROC) curve. The area under the ROC curve was 0.78, and the maximal sum of sensitivity and specificity (78% and 72%, respectively) was obtained at a 1,5-AG cutoff level of <14.2μg/mL. We conclude that 1,5-AG values may provide an ancillary predictor of 2h-PG of 75 g OGTTs in routine medical checkups.

View full abstract

Recent advances in ultrasonography and fine needle aspiration biopsy (FNAB) have facilitated accurate diagnosis of thyroid carcinomas that require treatment. However, we often encounter nodules evaluated as malignant on ultrasonography but diagnosed as benign on cytology, for which the optimal treatment strategy remains uncertain. A 28-year-old female had solitary and solid thyroid nodule measuring 6 cm in maximal diameter in February 1994. The lesion was cytologically diagnosed as benign. From September 1998, the nodule spontaneously decreased in size but ultrasonographic findings suspicious of malignancy such as peripheral and intra-tumoral calcification, low internal echo and irregular border gradually appeared. In July 2010, the volume of her nodule showed 97% decrease but was evaluated as papillary carcinoma on ultrasonography. FNAB was performed again and the nodule was diagnosed as benign. When we encounter a nodule showing ultrasonographic findings suggestive of malignancy with negative cytology, we should consider the possibility of a benign nodule degenerating over time.

View full abstract

To explore the relationship between serum thyrotropin and components of metabolic syndrome in a Chinese cohort. A total of 1534 adult inhabitants in DaDong district of Shenyang were asked to fulfill the questionnaire, complete physical examination and OGTT. Blood samples were collected to test thyrotropin (TSH), fasting plasma glucose (FPG), OGTT 2h PG, fasting insulin (FINS), triglyceride (TG) and high density lipoprotein cholesterol (HDL-C). Serum TSH in metabolic syndrome group was higher than that in the non-metabolic syndrome group (2.54 mIU/L vs. 2.22 mIU/L, p‹0.05). TG level increased significantly in subclinical hypothyroid group compared with euthyroid subjects (1.73±0.12 mmol/L vs. 1.47±0.03 mmol/L, p‹0.05), and HDL-C decreased significantly in patients with subclinical hypothyroidism compared with euthyroid subjects (1.26±0.27 mmol/L vs. 1.33±0.27 mmol/L, p‹0.05). The prevalence of hypertension was higher in the subclinical hypothyroid group than that in euthyroid group (42.86% vs. 33.2%, p‹0.05). The serum TSH within the reference range was positively related with the prevalence of overweight/obesity. Slight increase in serum TSH maybe a risk factor for metabolic syndrome.

View full abstract

Fine-needle aspiration cytology (FNAC) is the primary means to distinguish benign thyroid nodules from malignant ones. About 20% of FNAC yields indeterminate results leading to unnecessary or delayed surgery. Many studies of tissue samples, the majority of which are retrospective advocate testing for RET rearrangements as a diagnostic adjunctive tool in thyroid nodules with indeterminate cytological findings. Because of the uncertain prevalence of RET rearrangements, its utility as a tumor marker is still controversial. The goal of this study was to establish the prevalence and the utility of testing for RET rearrangements in FNAC suspicious of cancer in a clinical setting. In this prospective study, we analysed a large series of thyroid aspirates by RT-PCR only and Southern blot on RT-PCR products for type 1 and 3 RET rearrangements. Results were compared with clinical findings, cytological diagnosis and final histopathology. By the higher sensitive Southern-blot on RT-PCR method, RET rearrangements were present in 36% of papillary thyroid carcinomas (RET/PTC-1, 12%; RET/PTC-3, 20%; both, 4%) and of 13.3% of benign nodules. By means of RT-PCR only, RET rearrangements were disclosed only in 14.3% of PTC and in 3.6% of benign nodules. No significant correlation was found between RET rearrangements and clinicopathological features of patients. These results indicate that molecular testing of thyroid nodules for RET/PTC must take into account of its high prevalence in benign nodules, inducing false positive diagnoses when the highly sensitive assay Southern-blot on RT-PCR is used. Its searching by means of RT-PCR only, has a specificity superior of conventional cytology and can be used to refine inconclusive FNAC.

View full abstract

Bone morphogenetic protein 4 (BMP-4) is involved in the earliest stages of adipocyte differentiation and is recognized as an adipogenic factor for white adipose tissue. The association of serum BMP-4 levels with anthropometric and metabolic parameters has not been previously studied. We aimed to explore the relationship of serum BMP-4 levels with obesity and metabolic syndrome. Serum BMP-4 levels were measured in 104 non-diabetic individuals from the Chungju Metabolic Disease Cohort Study. Anthropometric measurements and components of metabolic syndrome were assessed in all patients. Serum BMP-4 levels were significantly increased in individuals with obesity or metabolic syndrome. After adjusting for age and gender, serum BMP-4 levels were positively correlated with body mass index, waist circumference (WC), waist-to-hip ratio, fasting plasma insulin, homeostasis model assessment index, and triglycerides and were negatively correlated with high-density lipoprotein (HDL) cholesterol. Among these parameters, WC and HDL cholesterol were found to be independent contributing factors for serum BMP-4 levels. Serum BMP-4 levels were also significantly higher in subjects with positive diagnostic criteria for each component of metabolic syndrome. The area under the receiver operating characteristic curve for BMP-4 was 0.661 (P = 0.022, 95% CI = 0.528 to 0.794) and the cut-off value was 2.84 pg/mL. This is the first demonstration that serum BMP-4 levels are associated with adiposity, insulin resistance, and the presence of metabolic syndrome. Whether BMP-4 may be involved in the pathogenesis of obesity and metabolic syndrome deserves further investigation.

View full abstract

Preeclampsia is characterized by the onset of high blood pressure and proteinuria during pregnancy, which results in substantial maternal and neonatal morbidity and mortality. Insulin resistance has been observed before the onset of preeclampsia, and is implicated in its pathophysiology. Recently, retinol-binding protein 4 (RBP4), which carries retinol in circulation, has been shown to be a potential regulator of insulin resistance originating from adipose tissue. Here we measured insulin resistance and RBP-4 levels in patients with preeclampsia and in women with normal pregnancies matched for gestational age and body mass index at Okayama University Hospital. Our aim was to examine the potential role of RBP4 in the pathophysiology of this disorder. There were no significant differences in RBP4 levels between all patients with preeclampsia and controls. However, the RBP4 level and homeostasis model assessment as an index of insulin resistance (HOMA-IR) in overweight patients with late-onset preeclampsia were significantly higher than in overweight controls carrying normal pregnancies and in normal weight women with late-onset preeclampsia. In contrast, there were no significant differences between the overweight and normal weight groups among patients with early-onset preeclampsia and in healthy pregnant women. These data suggest that RBP4 might act in the pathophysiology of late-onset preeclampsia via increased insulin resistance in obese women.

View full abstract

Serum levels of TSH receptor antibody (TRAb) often increase after radioiodine treatment for Graves’ disease, and high-serum levels of maternal TRAb in late pregnancy indicate a risk of neonatal hyperthyroidism. The aim of this retrospective study is to investigate the characteristics of Graves’ women who had a history of radioiodine treatment for intractable Graves’ disease, and whose neonates suffered from hyperthyroidism. The subjects of this study were 45 patients with Graves’ disease who became pregnant during the period from 1988 to 1998 after receiving radioiodine treatment at Ito Hospital. 25 of the 45 subjects had had a relapse of hyperthyroidism after surgical treatment for Graves’ disease. 19 pregnancies were excluded because of artificial or spontaneous abortion. In the remaining 44 pregnancies of 35 patients, neonatal hyperthyroidism developed in 5 (11.3%) pregnancies of 4 patients. Serum levels of TRAb at delivery were higher in patients whose neonates suffered from hyperthyroidism (NH mother) than those of patients who delivered normal infants (N mother). Furthermore, serum levels of TRAb in NH mother did not change during pregnancy, although those of 4 patients of N mother, in which serum levels of TRAb before radioiodine treatment were as high as in NH mother, decreased significantly during pregnancy. In conclusion, women who delivered neonates with hyperthyroidism following radioiodine treatment seem to have very severe and intractable Graves’ disease. Persistent high TRAb values during pregnancy observed in those patients may be a cause of neonatal hyperthyroidism.

View full abstract

Red blood cell (RBC) zinc (Zn) concentration reflects a patient’s mean thyroid hormone level over the preceding several months. The aim of this study was to examine whether RBC Zn level can be used as an indicator to distinguish painless thyroiditis-associated transient hypothyroidism (TH) from permanent hypothyroidism (PH). RBC Zn level was measured in 30 untreated PH patients with Hashimoto’s thyroiditis and 7 untreated TH patients with painless thyroiditis in whom preceding transient thyrotoxicosis had been confirmed. RBC Zn concentration was significantly lower in TH patients than that in PH patients. There was a positive correlation between RBC Zn and serum TSH, and the latter was clearly lower in TH patients than that in PH patients. However, RBC Zn level was again significantly lower in TH patients than PH patients despite of the comparable serum TSH levels in both groups when RBC Zn was evaluated in patients with serum TSH levels of less than 50 mU/L. Thus TH patients could be identified with RBC Zn measurement, allowing us avoidance of unnecessarily prolonged T4 administration to them.

View full abstract

Adult growth hormone deficiency (AGHD) is a recently recognized endocrine disorder characterized by low peak GH levels during provocative tests. The AGHD has a negative impact on bone mineral density, skeletal muscle strength, physical capacity and psychosocial well-being. Furthermore, the girls with GHD have delayed pubertal development, and in adulthood present a condition of subfertility. Treatment for AGHD with GH replacement therapy has been officially approved since 2006 in Japan. The patient was diagnosed as pituitary dwarfism at age 9. She was treated with GH replacement therapy since diagnosis until her height reached 155cm at age 15. When she was 24 years old, she suffered from clinical symptoms relating to GH deficiency, and she visited our hospital for reintroduction of the therapy to alleviate these clinical symptoms. She has been treated with the replacement therapy since then. The patient’s dysmenorrhea improved. And she was found to be 8 weeks pregnant at age 28 years 7 months. We immediately ceased replacement therapy and carefully observed the patient, because it is not indicated for female patient with pregnancy. She delivered a healthy girl at 40 weeks of pregnancy, no recognizable side-effects were observed in either mother or baby. To our knowledge, there are no other reports of a Japanese patient becoming pregnant during GH replacement therapy, and few cases have been reported in other countries. It remains uncertain whether the therapy is safe and essential for fetal development, fertility, and continuation of pregnancy in AGHD subjects.

View full abstract

We investigated the inhibitory effect of sitagliptin on albuminuria in patients with type 2 diabetes. Thirty-six patients (19 men and 17 women) whose HbA1c was higher than 6.5% (NGSP) despite receiving education on diet and exercise and medical treatment for at least 6 months at our clinic were enrolled into this study and were successfully followed over 6 months of sitagliptin treatment. Sitagliptin (50 mg/day) treatment significantly lowered both systolic and diastolic blood pressures, fasting blood glucose and postprandial blood glucose, HbA1c, and glycated albumin at 3 months and 6 months. Significant reductions in highly sensitive C-reactive protein and soluble vascular cell adhesion molecule 1 were also observed at 6 months. Urinary albumin excretion (measured as urinary albumin-to-creatinine ratio (ACR: mg/g Cr)) did not change in the 6 months before sitagliptin treatment (ΔACR: 2.3 ± 19.9) and decreased in the 6 months after sitagliptin treatment (ΔACR: -20.6 ± 24.6); these differences were statistically significant. At 6 months, the ACR decreased from 11.6 ± 8.4 to 4.5 ± 5.0 in 13 patients with normoalbuminuria (ACR < 30), from 98.4 ± 79 to 24.9 ± 20 in 15 patients with microalbuminuria (30 < ACR < 300), and from 1263 ± 492 to 561 ± 89 in 8 patients with macroalbuminuria (ACR > 300). Thus, the present findings strongly suggest that sitagliptin reduces albuminuria without lowering the estimated glomerular filtration rate, most likely depending on known factors such as blood sugar reduction, blood pressure reduction, and inflammation reduction, as well as yet undetermined factors caused by an increase in active glucagon-like peptide-1.

View full abstract