Brown adipose tissue (BAT) is the site of sympathetically activated adaptive thermognenesis during cold exposure and after hyperphagia, thereby controlling whole-body energy expenditure (EE) and body fat. Radionuclide imaging studies have demonstrated that adult humans have metabolically active BAT composed of mainly beige/brite adipocytes, recently identified brown-like adipocytes. The inverse relationship between the BAT activity and body fatness suggests that BAT is, because of its energy dissipating activity, protective against body fat accumulation in humans as it is in small rodents. In fact, either repeated cold exposure or daily ingestion of some food ingredients acting on transient receptor potential channels recruits BAT in parallel with increased EE and decreased body fat. In addition to the sympathetic nervous system, several endocrine factors are also shown to recruit BAT. Thus, BAT is a promising therapeutic target for combating human obesity and related metabolic disorders.

View full abstract

An 88-year-old male patient with macroglobulinemia was admitted to our hospital because of severe hyponatremia and unconsciousness. Laboratory findings showed decreased inhibition of antidiuretic hormone (ADH) and he was diagnosed with syndrome of inappropriate secretion of ADH (SIADH). Hyponatremia improved with only limitation of water intake and the patient was followed up on a continuing outpatient basis. However, soon after discharge from hospital, his legs started swelling with edema and hyponatremia worsened. He was re-admitted due to a fall at home. Hyponatremia was observed at re-admission. A CRH challenge test showed partial dysfunction of ACTH secretion. Corticosteroid therapy was performed, but the patient subsequently died from pneumonia. Pathological findings at autopsy revealed invasion of plasma cells and amyloid depositions in multiple organs, including the pituitary, adrenal cortex, heart, liver, kidney, lymph nodes and bone marrow. Consistent with these results, fibrosis was observed in the anterior lobe of the pituitary, suggesting that the autopsy findings were related to the clinical observations and diagnosis. This is the first reported case of macroglobulinemia complicated with multiple hormone dysfunction

View full abstract

The objective of this study was to assess the chronic effects of a bile acid sequestrant, colestimide, on glucose metabolism. After db/db mice were fed a diet containing colestimide or cholic acid (CA) for 12 weeks, we investigated the impact of these agents on glucose and lipid metabolism. Colestimide significantly reduced the elevated fasting blood glucose level (p<0.01), and CA even more markedly reduced fasting blood glucose. The blood glucose level after an oral glucose load was significantly lower in the CA group than in the control group, but the colestimide group showed no significant difference. The insulin response to a glucose load was abolished in the control and colestimide groups. A hyperinsulinemic-euglycemic clamp study revealed that colestimide significantly improved the GIR (p=0.013). Hepatic EGP and Rd were also improved by colestimide, suggesting that it alleviated insulin resistance by suppressing hepatic glucose production and increasing peripheral glucose usage. CA significantly increased both the weight and cholesterol content of the liver, while colestimide reduced these parameters. Colestimide suppressed hepatic gene expression of SHP, but enhanced SREBP2 expression. On the other hand, CA increased the expression of SHP and lipogenic enzymes such as ACC and SCD-1, but had no effect on SREBP2. The present study demonstrated that colestimide improves hyperglycemia and hyperlipidemia, as well as reducing the hepatic lipid content. In contrast, CA exacerbates hyperlipidemia and increases the hepatic lipid content, although it improves glycemic control. Thus, colestimide is a well-balanced drug for the treatment of diabetes mellitus.

View full abstract

Results of published studies on the association of the ADIPOQ T45G polymorphism with insulin resistance (IR) and blood glucose are conflicting. In this study, we performed a meta-analysis to further investigate such an association. Articles that evaluate the effect of the T45G polymorphism on IR and blood glucose were identified from the PubMed and Embase databases. Five indices, including fasting blood glucose (FBG), fasting insulin (F-insulin), 2-h blood glucose (2-h BG), 2-h insulin, and homeostasis model assessment insulin resistance index (HOMA-IR), were used to assess the effects of the T45G polymorphism on IR and blood glucose under a dominant model. 24 articles involving 7630 subjects were included. Twenty-two studies on FBG, 17 on F-insulin, 20 on HOMA-IR, and 3 on 2-h BG were included. No study on 2-h insulin was found. This meta-analysis revealed no significant association between the ADIPOQ T45G polymorphism and IR and blood glucose in the overall population and subgroup subjects under a dominant model, regardless of whether FBG, F-insulin, 2-h BG, or HOMA-IR was used. The present meta-analysis indicated that the mutation allele may have no function in IR development. The ADIPOQ T45G polymorphism is not associated with IR and blood glucose.

View full abstract

We investigated the efficacy of once- and thrice-daily voglibose, an alpha-glucosidase inhibitor, as an add-on therapy to alogliptin, a dipeptidyl peptidase-4 inhibitor, on glycemic control in Japanese type 2 diabetic patients. In this 12-week, parallel-group, randomized, open-label, three-arm trial, 151 participants treated with alogliptin were randomly allocated to the following three arms; one was the group to initiate once-daily voglibose, another was to initiate thrice daily voglibose, and the other was the control group. The primary endpoint was the change of hemoglobin A1c levels at the end of the study, which was revealed to be significantly different among groups (p < 0.001). The once- and thrice-daily voglibose groups had a significantly greater reduction than the control group; the difference was -0.27% and -0.33% in the once- and thrice-daily voglibose group, respectively (both p < 0.001). No significant difference was observed between the two voglibose groups (p = 0.615). On the other hand, the increase of 1,5-anhydroglucitol levels were 3.3 and 5.5 μg/ml greater in the once- and thrice-daily voglibose groups than the control group (both p < 0.001). The thrice-daily voglibose group had a greater increase of 1,5- anhydroglucitol levels compared to the once-daily voglibose group (p = 0.005). In conclusion, once- and thrice-daily voglibose as an add-on to alogliptin significantly improved glycemic control in Japanese type 2 diabetic patients.

View full abstract

Obesity-associated hepatic lipid accumulation and chronic low-grade inflammation lead to metabolic defects. Saturated fatty acids (SFA) are a risk factor for, whereas unsaturated fatty acids (UFA) are thought to be protective against, developing metabolic diseases. Sex differences exist in the regulation of metabolism. We tested the hypothesis that diets high in SFA, mono-UFA (MUFA), or poly-UFA (PUFA) had early, sex-distinct effects that differentially contribute to long-term metabolic disturbance such as fatty liver and insulin resistance. Metabolic changes including body and fat mass, circulating leptin and glucose levels, plasma lipid profile, hepatic lipid accumulation, expression levels of genes related to lipid metabolism and low-grade inflammation, and tissue insulin sensitivity were compared between male and female mice fed with a low-fat chow, or high-fat SFA, MUFA, or PUFA for a short period of four days. SFA and MUFA males increased adiposity associated with increased liver lipid accumulation and rapid activation of inflammation in adipose and muscle tissues, whereas PUFA males did not show lipid accumulation or tissue inflammation compared to chow males. All SFA and UFA males displayed tissue insulin resistance. In contrast, female high-fat diet groups had normal liver lipid content and maintained tissue insulin sensitivity without showing tissue inflammation. Therefore, sex differences existed during early phase of development of metabolic dysfunction. The beneficial effects of PUFA, but not MUFA, were corroborated in protection of obesity, hyperlipidemia, fatty liver, and low-grade inflammation. The benefit of MUFA and PUFA in maintaining tissue insulin sensitivity in males, however, was questioned.

View full abstract

Obesity is a global health problem that increases the risk of several common diseases. Liver receptor homologue-1 (LRH-1) has an important role in steroid hormone metabolism, which influences body weight. Whether LRH-1 gene deletion causes obesity is yet to be clarified. In this study using LRH-1 heterozygous knockout (LRH-1^+/-) mice, we investigated the role of LRH-1 on body weight gain and glucose and lipid metabolism. LRH-1^+/- mice showed mild but significant body weight gains compared with wild-type littermate mice after being fed a high-fat diet. We performed glucose tolerance tests and insulin tolerance tests and did not find any significant differences between wild-type and LRH-1^+/- mice. To clarify how LRH-1 gene deletion affects body weight gain, we measured food intake, oxygen consumption, respiratory quotient, spontaneous activity and rectal temperature, and found no significant differences between wild-type and LRH-1^+/- mice fed a normal diet and a high-fat diet. The results suggest that heterozygous gene deletion of LRH-1 causes body weight gains without any apparent worsening of glucose and lipid metabolism. Identifying the effects of LRH-1 on body weight will aid in understanding the pathogenesis of obesity.

View full abstract

Cancer stem-like cells (CSCs) play important roles in cancer initiation and progression. CSCs have been isolated using several markers, but those for thyroid CSCs remain to be confirmed. We therefore conducted a comprehensive search for thyroid CSC markers. Expression of nine cell surface markers (CD13, CD15, CD24, CD44, CD90, CD117, CD133, CD166, and CD326) and aldehyde dehydrogenase (ALDH) activity, which are CSC markers in various solid cancers, and the ability to form spheres in vitro and tumors in vivo were investigated using eight thyroid cancer cell lines (FRO, KTC1/2/3, TPC1, WRO, ACT1, and 8505C). Among these, four cell lines (FRO, KTC3, ACT1, and 8505C) possessed the both abilities; however, common markers indicative of CSCs were not observed. The pattern of ability to form spheres was completely matched to that of tumor formation, suggesting that our sphere assay is valuable for assessment of tumor-forming ability. Next, the cells were sorted using these markers and subjected to the sphere assay. In three cell lines (FRO, KTC3, and ACT1), ALDH^pos cells showed higher sphere forming ability than ALDH^neg cells but not in other cells. CD326^hi also appeared to be a candidate marker only in FRO cells. However, these subpopulations did not follow a classical hierarchical model because ALDH^neg and CD326^low fractions also generated ALDH^pos and CD326^hi cells, respectively. These data suggest that ALDH activity is probably a major candidate marker to enrich thyroid CSCs but not universal; other markers such as CD326 that regulate different CSC properties may exist.

View full abstract

Among the several prognostic factors of papillary thyroid carcinoma (PTC), age is the most prominent. It is well known that elderly PTC patients have poorer prognoses. Here we investigated the prognostic impact of young age in univariate and multivariate analyses. We retrospectively analyzed 5,733 PTC patients without distant metastasis at presentation, who underwent initial surgery at Kuma Hospital. The median follow-up period was 150 months. We classified the patients into three groups: young (< 30 years), middle-aged (30−59), and older patients (≥ 60 years). The tumor size was larger and clinical node positivity was higher in the young patients, and significant extrathyroid extension was higher in the older patients compared to the other two groups. In the univariate analysis, the young patients showed poorer extrathyroidal locoregional and distant recurrence rates than the middle-aged patients, but not cause-specific survival rates. In the multivariate analysis, age < 30 years was an independent or marginal predictor of extrathyroidal locoregional and distant recurrence, but not of carcinoma-related death. Age ≥ 60 years independently affected PTC recurrence and death. Taken together, we should carefully treat young PTC patients because of the likeliness of extrathyroidal locoregional and distant recurrence, which may not be life-threatening.

View full abstract

Our previous studies have revealed that protein malnutrition enhances insulin signaling in rat liver and muscle in response to a bolus insulin injection. However, it has not been established whether protein malnutrition up-regulates insulin signaling under physiological conditions, such as feeding. Here, we studied the effects of protein malnutrition on insulin signaling after feeding in rat liver, muscle and white adipose tissue (WAT). Six-week-old rats were fed a 15% casein diet (15C) or a calorie-matched 5% casein diet (5C) for 8 h/day during 14 days. On the 15th day, blood and tissues were collected at various time points after feeding. Feeding-induced insulin secretion was reduced in 5C-fed rats compared to 15C-fed rats. The 5C-feeding suppressed immediate activation of insulin receptor after feeding in the liver, muscle, and WAT. However, 5C-feeding constantly increased tyrosine phosphorylation of insulin receptor substrate (IRS)-2 and threonine phosphorylation of eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) in the liver during the examined periods, corresponding to the changes of their amounts. In skeletal muscle, 5C-feeding did not appreciably alter insulin signaling. In WAT, 5C-feeding decreased tyrosine phosphorylation of IRS-1 compared to 15C-feeding. Furthermore, hepatic triglyceride content was increased and feeding-induced acetyl-CoA carboxylase 1 gene expression was enhanced in 5C-fed rats. The 5C-feeding decreased insulin-dependent glucose uptake in adipocytes. These results suggest that enhanced insulin signaling through increased IRS-2 and 4E-BP1 levels in the liver and repressed insulin signaling through decreased IRS-1 levels in WAT contribute to the preferential hepatic lipid accumulation under protein malnutrition.

View full abstract

Sitagliptin was used as monotherapy or in combination with metformin, thiazolidinedione or sulfonylurea. It is not clear whether effects are enhanced or unique when in combination with transient continuous subcutaneous insulin infusion (CSII) therapy. The aim of this study was to assess the safety and efficacy of sitagliptin in combination with transient CSII therapy in patients with newly diagnosed type 2 diabetes. Eighty patients with newly diagnosed type 2 diabetes from July 2011 to May 2013 were recruited into the study. These patients were randomly divided into a CSII monotherapy group (group A, n = 40) or a sitagliptin in combination with CSII therapy group (group B, n = 40) and received insulin intensive therapy. Treatments were maintained for 2 weeks. 75g oral glucose tolerance test (OGTT) was performed before and after treatments, and the levels of glucose, insulin and C-peptide were examined. The results indicated that, compared with CSII therapy group, the level of plasma glucose significantly decreased, the levels of insulin and C-peptide strikingly increased and homeostasis model assessment for beta-cell function (HOMA-β) and Insulinogenic index (Ins index) were improved in the group of sitagliptin in combination with CSII therapy. Above all, the incidence of hypoglycemia was lower, insulin doses were less and the rate of recovery to normal glucose tolerance (NGT) or impaired glucose tolerance (IGT) determined by 75gOGTT was higher in the latter. So, Sitagliptin in combination with CSII therapy can be a new safe and effective therapy in patients with newly diagnosed type 2diabetes.

View full abstract

Previously we reported that the phosphorylation of Synip on serine 99 is required for Synip dissociation from Syntaxin4 and insulin-stimulated Glut4 translocation in cultured 3T3-L1 adipocytes. We also reported that the dissociated Synip remains anchored to the plasma membrane by binding to Phosphatidylinositol (3,4,5)-triphosphate. Recently Synip was reported to arrest SNARE-dependent membrane fusion as a selective t-SNARE binding inhibitor. In this study, we have found that Synip is expressed in podocytes although at a somewhat lower level than in adipocytes. To determine whether phosphorylation of Synip on serine 99 is required for insulin-stimulated Glut4 translocation and glucose uptake in podocytes we expressed a phosphorylation deficient Synip mutant (S99A-Synip) that inhibited insulin-stimulated Glut4 translocation and 2-deoxyglucose uptake in adipocytes. We conclude that serine 99 phosphorylation of Synip is required for Glut4 translocation and glucose uptake in both adipocytes and podocytes, suggesting that defects in Synip phosphorylation may underlie insulin resistance and associated diabetic nephropathy.

View full abstract