The PDK1-FoxO1 signaling in adipocytes controls systemic insulin sensitivity through the 5-lipoxygenase-leukotriene B4 axis.

Although adipocytes are major targets of insulin, the influence of impaired insulin action in adipocytes on metabolic homeostasis remains unclear. We here show that adipocyte-specific PDK1 (3'-phosphoinositide-dependent kinase 1)-deficient (A-PDK1KO) mice manifest impaired metabolic actions of insulin in adipose tissue and reduction of adipose tissue mass. A-PDK1KO mice developed insulin resistance, glucose intolerance, and hepatic steatosis, and this phenotype was suppressed by additional ablation of FoxO1 specifically in adipocytes (A-PDK1/FoxO1KO mice) without an effect on adipose tissue mass. Neither circulating levels of adiponectin and leptin nor inflammatory markers in adipose tissue differed between A-PDK1KO and A-PDK1/FoxO1KO mice. Lipidomics and microarray analyses revealed that leukotriene B4 (LTB4) levels in plasma and in adipose tissue as well as the expression of 5-lipoxygenase (5-LO) in adipose tissue were increased and restored in A-PDK1KO mice and A-PDK1/FoxO1KO mice, respectively. Genetic deletion of the LTB4 receptor BLT1 as well as pharmacological intervention to 5-LO or BLT1 ameliorated insulin resistance in A-PDK1KO mice. Furthermore, insulin was found to inhibit LTB4 production through down-regulation of 5-LO expression via the PDK1-FoxO1 pathway in isolated adipocytes. Our results indicate that insulin signaling in adipocytes negatively regulates the production of LTB4 via the PDK1-FoxO1 pathway and thereby maintains systemic insulin sensitivity.

Fsp27 plays a crucial role in muscle performance.

Fsp27 was previously identified as a lipid droplet-associated protein in adipocytes. Various studies have shown that it plays a role in the regulation of lipid homeostasis in adipose tissue and liver. However, its function in muscle, which also accumulate and metabolize fat, remains completely unknown. Our present study identifies a novel role of Fsp27 in muscle performance. Here, we demonstrate that Fsp27-/- and Fsp27+/- mice, both males and females, had severely impaired muscle endurance and exercise capacity compared with wild-type controls. Liver and muscle glycogen stores were similar among all groups fed or fasted, and before or after exercise. Reduced muscle performance in Fsp27-/- and Fsp27+/- mice was associated with severely decreased fat content in the muscle. Furthermore, results in heterozygous Fsp27+/- mice indicate that Fsp27 haploinsufficiency undermines muscle performance in both males and females. In summary, our physiological findings reveal that Fsp27 plays a critical role in muscular fat storage, muscle endurance, and muscle strength.NEW & NOTEWORTHY This is the first study identifying Fsp27 as a novel protein associated with muscle metabolism. The Fsp27-knockout model shows that Fsp27 plays a role in muscular-fat storage, muscle endurance, and muscle strength, which ultimately impacts limb movement. In addition, our study suggests a potential metabolic paradox in which FSP27-knockout mice presumed to be metabolically healthy based on glucose utilization and oxidative metabolism are unhealthy in terms of exercise capacity and muscular performance.

Dose-dependent accumulation of glucose in the intestinal wall and lumen induced by metformin as revealed by 18 F-labelled fluorodeoxyglucose positron emission tomography-MRI.

AIM: To investigate the relationships between various clinical variables and the metformin-induced accumulation of fluorodeoxyglucose (FDG) in the intestine, with distinction between the intestinal wall and lumen, in individuals with type 2 diabetes who were receiving metformin treatment and underwent 18 F-labelled FDG ([18 F]FDG) positron emission tomography (PET)-MRI. MATERIALS AND METHODS: We evaluated intestinal accumulation of [18 F]FDG with both subjective (a five-point visual scale determined by two experienced radiologists) and objective analyses (measurement of the maximum standardized uptake value [SUVmax ]) in 26 individuals with type 2 diabetes who were receiving metformin and underwent [18 F]FDG PET-MRI. [18 F]FDG accumulation within the intestinal wall was discriminated from that in the lumen on the basis of SUVmax . RESULTS: SUVmax for the large intestine was correlated with blood glucose level (BG) and metformin dose, but not with age, body mass index, HbA1c level or estimated glomerular filtration rate (eGFR). SUVmax for the small intestine was not correlated with any of these variables. Visual scale analysis yielded essentially similar results. Metformin dose and eGFR were correlated with SUVmax for the wall and lumen of the large intestine, whereas BG was correlated with that for the wall. Multivariable analysis identified metformin dose as an explanatory factor for SUVmax in the wall and lumen of the large intestine after adjustment for potential confounders including BG and eGFR. CONCLUSIONS: Metformin dose is an independent determinant of [18 F]FDG accumulation in the wall and lumen of the large intestine in individuals treated with this drug.

Effects of insulin degludec and insulin glargine U300 on glycaemic stability in individuals with type 1 diabetes: A multicentre, randomized controlled crossover study.

To compare the effects of insulin degludec (IDeg) and insulin glargine U300 (IGlarU300) on glycaemic stability in subjects with type 1 diabetes. MATERIALS AND METHODS: In this multicentre, crossover trial, 46 individuals with type 1 diabetes and essentially undetectable circulating C-peptide were randomly assigned to either the IDeg-first/IGlarU300-second group or the IGlarU300-first/IDeg-second group, and were treated with the respective basal insulins for 4-week periods. Data were collected in the last week of each treatment period. The primary aim was to examine the potential non-inferiority of IDeg relative to IGlarU300 with regard to day-to-day variability, as evaluated by the standard deviation (SD) of fasting blood glucose (FBG) levels. Intra-day glycaemic variability and other variables were also determined by continuous glucose monitoring (CGM). RESULTS: The SD of FBG for IDeg was non-inferior to that for IGlarU300. The mean of FBG, coefficient of variation of FBG, and various glycaemic variability indexes determined by CGM did not differ between the two insulins. Whereas the administered doses of the insulins also did not differ, the mean glycaemic value was lower for IDeg than IGlarU300; the time above the target range (>180 mg/dL [10.0 mmol/L]) and the time below the target range (<70 mg/dL [3.9 mmol/L]) were shorter and longer, respectively, for IDeg than IGlarU300. CONCLUSIONS: Our data suggest that IDeg and IGlarU300 have comparable glucose-stabilizing effects in individuals with type 1 diabetes. However, the glucose-lowering effect of IDeg may be greater than that of IGlarU300 when titrated with a unit-based protocol.

Relation between HOMA-IR and insulin sensitivity index determined by hyperinsulinemic-euglycemic clamp analysis during treatment with a sodium-glucose cotransporter 2 inhibitor.

We had aimed to determine whether homeostasis model assessment-insulin resistance (HOMA-IR) reflects insulin resistance-sensitivity during treatment with a sodium-glucose cotransporter 2 inhibitor (SGLT2i). Hyperinsulinemic-euglycemic clamp analysis was performed in 22 patients with type 2 diabetic patients taking dapagliflozin (5 mg/day before or after breakfast). Propensity score matching of these individuals (SGLT2i group) for age, sex, body mass index, and clamp-derived tissue glucose uptake rate with 44 type 2 diabetic patients who had undergone clamp analysis without SGLT2i treatment (control group) identified 17 paired subjects in each group for further analysis of the relation between HOMA-IR and a clamp-derived insulin sensitivity index (ISI). Natural log-transformed HOMA-IR was negatively correlated with ISI in both SGLT2i (r = -0.527, p = 0.030) and control (r = -0.534, p = 0.027) groups. The simple regression lines for log-transformed HOMA-IR and ISI in the two groups showed similar slopes but differed in their intercepts. Multivariate analysis revealed that HOMA-IR for patients with the same ISI in the two groups was related by the formula: HOMA-IRcontrol = HOMA-IRSGLT2i × 2.45. In conclusion, HOMA-IR was well correlated with ISI during SGLT2i treatment, but values corresponding to the same ISI were lower in the SGLT2i group than in the control group.

Cell death-inducing DNA fragmentation factor A-like effector A and fat-specific protein 27ß coordinately control lipid droplet size in brown adipocytes.

Adipose tissue stores neutral lipids and is a major metabolic organ involved in regulating whole-body energy homeostasis. Triacylglycerol is stored as unilocular large lipid droplets (LDs) in white adipocytes and as multilocular small LDs in brown adipocytes. Proteins of the cell death-inducing DNA fragmentation factor A-like effector (Cide) family include CideA, CideB, and fat-specific protein of 27 (FSP27). Of these, FSP27 has been shown to play a crucial role in the formation of unilocular large LDs in white adipocytes. However, the mechanisms by which brown adipocytes store small and multilocular LDs remain unclear. An FSP27 isoform, FSP27ß, was recently identified. We herein report that CideA and FSP27ß are mainly expressed in brown adipose tissue and that FSP27ß overexpression inhibits CideA-induced LD enlargements in a dose-dependent manner in COS cells. Furthermore, RNAi-mediated FSP27ß depletion resulted in enlarged LDs in HB2 adipocytes, which possess the characteristics of brown adipocytes. Brown adipocytes in FSP27-knock-out mice that express CideA, but not FSP27ß, had larger and fewer LDs. Moreover, we confirmed that FSP27ß and CideA form a complex in brown adipose tissue. Our results suggest that FSP27ß negatively regulates CideA-promoted enlargement of LD size in brown adipocytes. FSP27ß appears to be responsible for the formation of small and multilocular LDs in brown adipose tissue, a morphology facilitating free fatty acid transport to mitochondria adjacent to LDs for oxidation in brown adipocytes.

Circulating progranulin level is associated with visceral fat and elevated liver enzymes: significance of serum progranulin as a useful marker for liver dysfunction.

Progranulin (PRGN) was recently identified as one of the adipokines involved in the development of insulin resistance. Thus, the aim of this study was to explore the importance of PRGN as a novel marker for metabolic diseases in Japanese. A total of 138 subjects were recruited by the Aijinkai Total Health Care Center. Physical examination, blood sample examination and total body CT scan were performed for all participants. Serum PRGN levels were examined in subjects with or without metabolic syndrome and with or without liver enzyme elevation. Association study of serum PRGN levels and regression analysis of the relationship of elevated liver enzymes to representative metabolic parameters were performed. The metabolic syndrome group exhibited older age, and higher BMI, blood pressure, fasting glucose, HbA1c, IRI, HOMA-R, TG, FFA, CRP, AST, ALT, LDH, and ALP, and larger visceral fat area, subcutaneous fat area and visceral fat area/subcutaneous fat area. Serum PRGN concentrations were significantly higher in the metabolic syndrome group than in the non-metabolic syndrome group. Bivariate correlation analysis revealed that serum PRGN concentrations correlated positively and significantly with AST, ALT, LDH, γGTP, ALP, waist circumference and visceral fat area. The group with elevated liver enzymes exhibited higher BMI, blood pressure, IRI, HOMA-R, and PRGN level and larger waist circumference and visceral fat area than the group without them. In logistic regression analysis, visceral fat area and PRGN were significantly predictive of elevated liver enzymes. These results suggest that serum PRGN level as well as visceral fat are associated closely with liver dysfunction.

Obesity and risk for its comorbidities diabetes, hypertension, and dyslipidemia in Japanese individuals aged 65 years.

Diabetes, hypertension, and dyslipidemia are obesity-related comorbidities that contribute to the development of cardiovascular disease, one of the leading causes of death. In addition to obesity, the underweight condition is a concern because it can give rise to sarcopenia, particularly after the age of 65 years. We examined the risk for diabetes, hypertension, and dyslipidemia due to obesity in individuals of this age. We retrospectively investigated the relation between obesity and its three major comorbidities in 10,852 individuals aged 65 years who underwent health checkups implemented by Kobe City between April 2017 and March 2021. The prevalence of diabetes, hypertension, and dyslipidemia with and without hyper-low-density lipoprotein-cholesterolemia was 9.7%, 41.0%, 63.8%, and 19.5%, respectively, and the prevalence of these conditions increased with increasing obesity. The risk for diabetes and hypertension was increased markedly (odds ratios of 12.95 and 19.44, respectively), and that for dyslipidemia with and without hyper-low-density lipoprotein-cholesterolemia was modestly increased (odds ratios of 2.59 and 3.65, respectively) at a BMI of ≥ 35 kg/m2 compared with normal weight. Analysis by gender revealed that the obesity-related risk for dyslipidemia with hyper-low-density lipoprotein-cholesterolemia was small compared with other comorbidities in women, while the risk for all comorbidities elevated similarly in men. Our results suggest the importance of public health intervention for obesity to suppress its comorbidities, especially diabetes and hypertension, at this age.

Distinct hypoglycemic effect of different formulations of a fixed ratio of basal insulin plus glucagon-like peptide-1 receptor agonist in a patient with pancreatic diabetes.

Fixed-ratio combination injection therapy (FRC) is a fixed-ratio mixture containing basal insulin and glucagon-like peptide-1 receptor agonist (GLP-1 RA) in a single injection for the treatment of patients with type 2 diabetes. The two types of FRC products contain different concentrations and mixing ratios of basal insulin and GLP-1 RA. Both products demonstrated satisfactory blood glucose control throughout the day, with less hypoglycemia and weight gain. However, few studies have examined the differences in the actions of the two formulations. Herein, we present a case of a 71-year-old man with pancreatic diabetes and significantly impaired intrinsic insulin secretion capacity, who demonstrated a marked difference in glycemic control following treatment with two different FRC formulations. Treatment with IDegLira, an FRC product, demonstrated suboptimal glucose control in the patient. However, after a change in therapy to another FRC product, IGlarLixi, his glucose control markedly improved, even with a decrease in the injection dose. This difference could have been due to lixisenatide, a short-acting GLP-1RA contained in IGlarLixi, which exerts a postprandial hypoglycemic effect irrespective of intrinsic insulin secretion capacity. In conclusion, IGlarLixi has the potential to achieve good fasting and postprandial glucose control with a once-daily injection, even in patients with type 2 diabetes who have a reduced intrinsic insulin secretion capacity. Supplementary Information: The online version contains supplementary material available at 10.1007/s13340-023-00621-5.

Preoperative Serum Cortisol Level Is Predictive of Weight Loss After Laparoscopic Sleeve Gastrectomy in Men with Severe Obesity but Not Women.

BACKGROUND: Bariatric surgery is an effective treatment for severe obesity and its associated medical problems. Preoperative factors that predict postoperative weight loss remain to be fully characterized, however. METHODS: Anthropometric and laboratory data were collected retrospectively for severely obese patients who underwent laparoscopic sleeve gastrectomy (LSG) between April 2016 and July 2019 at our hospital. Preoperative factors that predicted weight loss at 1 year after LSG were investigated. RESULTS: A total of 122 subjects (45 men and 77 women) underwent LSG. The mean ± SD age and body mass index at surgery were 44.4 ± 10.4 years and 40.7 ± 6.7 kg/m2. The percent total weight loss (%TWL) was 27.0 ± 8.6 among all subjects, 26.4 ± 8.0 among men, and 27.4 ± 8.9 among women, with no significant difference between the sexes. The %TWL showed a significant inverse correlation with serum cortisol level in men and with age and the visceral/subcutaneous fat area ratio in women. Multivariable regression analysis revealed the presence of type 2 diabetes and the serum cortisol concentration to be negatively associated with %TWL among all subjects and men, respectively. Receiver operating characteristic curve analysis identified an optimal cutoff of 10 µg/dL for prediction of a %TWL of ≥ 25 in men by serum cortisol level. CONCLUSIONS: Serum cortisol concentration was identified as a predictor for postoperative weight loss in men. Our results may thus help inform the decision to perform LSG or more effective surgical procedures in men with severe obesity.

Regulation of fat specific protein 27 by isoproterenol and TNF-α to control lipolysis in murine adipocytes.

The lipid droplet-associated fat specific protein 27 (FSP27) suppresses lipolysis and thereby enhances triglyceride accumulation in adipocytes. We and others have recently found FSP27 to be a remarkably short-lived protein (half-life, 15 min) due to its rapid ubiquitination and proteasomal degradation. Thus, we tested the hypothesis that lipolytic agents such as tumor necrosis factor-α (TNF-α) and isoproterenol modulate FSP27 levels to regulate FFA release. Consistent with this concept, we showed that the lipolytic actions of TNF-α, interleukin-1ß (IL-1ß), and IFN-γ are accompanied by marked decreases in FSP27 expression and lipid droplet size in mouse adipocytes. Similar depletion of FSP27 using short interfering RNA (siRNA) mimicked the lipolysis-enhancing effect of TNF-α, while maintaining stable FSP27 levels using expression of hemagglutinin epitope-tagged FSP27 blocked TNF-α-mediated lipolysis. In contrast, we show the robust lipolytic action of isoproterenol is paradoxically associated with increases in FSP27 levels and a delayed degradation rate corresponding to decreased ubiquitination. This catecholamine-mediated increase in FSP27 abundance, probably a feedback mechanism for restraining excessive lipolysis by catecholamines, is mimicked by forskolin or 8-bromo-cAMP treatment and is prevented by the protein kinase A (PKA) inhibitor KT5720 or by PKA depletion using siRNA. Taken together, these data identify the regulation of FSP27 as an important intermediate in the mechanism of lipolysis in adipocytes in response to TNF-α and isoproterenol.

FSP27 contributes to efficient energy storage in murine white adipocytes by promoting the formation of unilocular lipid droplets.

White adipocytes are unique in that they contain large unilocular lipid droplets that occupy most of the cytoplasm. To identify genes involved in the maintenance of mature adipocytes, we expressed dominant-negative PPARgamma in 3T3-L1 cells and performed a microarray screen. The fat-specific protein of 27 kDa (FSP27) was strongly downregulated in this context. FSP27 expression correlated with induction of differentiation in cultured preadipocytes, and the protein localized to lipid droplets in murine white adipocytes in vivo. Ablation of FSP27 in mice resulted in the formation of multilocular lipid droplets in these cells. Furthermore, FSP27-deficient mice were protected from diet-induced obesity and insulin resistance and displayed an increased metabolic rate due to increased mitochondrial biogenesis in white adipose tissue (WAT). Depletion of FSP27 by siRNA in murine cultured white adipocytes resulted in the formation of numerous small lipid droplets, increased lipolysis, and decreased triacylglycerol storage, while expression of FSP27 in COS cells promoted the formation of large lipid droplets. Our results suggest that FSP27 contributes to efficient energy storage in WAT by promoting the formation of unilocular lipid droplets, thereby restricting lipolysis. In addition, we found that the nature of lipid accumulation in WAT appears to be associated with maintenance of energy balance and insulin sensitivity.

Crucial role of the small GTPase Rac1 in insulin-stimulated translocation of glucose transporter 4 to the mouse skeletal muscle sarcolemma.

The Rho family GTPase Rac1 has been implicated in the regulation of glucose uptake in myoblast cell lines. However, no evidence for the role of Rac1 has been provided by a mouse model. The purpose of this study is to test the involvement of Rac1 in insulin action in mouse skeletal muscle. Intravenous administration of insulin indeed elicited Rac1 activation in gastrocnemius muscle, suggesting the involvement of Rac1 in this signaling pathway. We then examined whether insulin-stimulated translocation of the facilitative glucose transporter GLUT4 from its storage sites to the skeletal muscle sarcolemma depends on Rac1. We show that ectopic expression of constitutively activated Rac1, as well as intravenous administration of insulin, caused translocation of GLUT4 to the gastrocnemius muscle sarcolemma, as revealed by immunofluorescent staining of a transiently expressed exofacial epitope-tagged GLUT4 reporter. Of particular note, insulin-dependent, but not constitutively activated Rac1-induced, GLUT4 translocation was markedly suppressed in skeletal muscle-specific rac1-knockout mice compared to control mice. Immunogold electron microscopic analysis of endogenous GLUT4 gave similar results. Collectively, we propose a critical role of Rac1 in insulin-dependent GLUT4 translocation to the skeletal muscle sarcolemma, which has heretofore been predicted solely by cell culture studies.

Clinical features of 65-year-old individuals in Japan diagnosed with possible sarcopenia based on the Asian Working Group for Sarcopenia 2019 criteria.

AIM: The prevalence of sarcopenia and the health status of affected individuals, particularly among the young elderly, are unclear in Japan. We determined the prevalence of possible sarcopenia, a concept proposed by the Asian Working Group for Sarcopenia (AWGS) in 2019, and then investigated its clinical features in community-dwelling young elderly individuals in Kobe, a representative large city in Japan. METHODS: This retrospective cross-sectional study examined 1768 residents of Kobe aged 65 years who underwent health and frailty checkups implemented by Kobe City between April 2017 and March 2019. Possible sarcopenia was diagnosed by the AWGS 2019 algorithm. Frailty status was assessed with the use of the Kihon Checklist, which was developed to identify senior citizens requiring nursing care in Japan. RESULTS: Fifty-one of the 1768 subjects were diagnosed with possible sarcopenia (overall prevalence of 2.9% [confidence interval: 2.1-3.7%]), with the prevalence being higher in women than in men. Individuals with possible sarcopenia had a lower body mass index, abdominal circumference, diastolic blood pressure and percentage of taking lipid-lowering drugs as well as a higher high-density lipoprotein cholesterol level and estimated glomerular filtration rate. They also showed a higher degree of frailty. A low body mass index and physical inactivity were significantly associated with possible sarcopenia. CONCLUSIONS: The prevalence of possible sarcopenia based on the AWGS 2019 criteria was 2.9% among 65-year-olds in Japan, with affected individuals more likely to be frail compared with those without this condition. Geriatr Gerontol Int 2021; 21: 689-696.

Relation of cardiac function to insulin resistance as evaluated by hyperinsulinemic-euglycemic clamp analysis in individuals with type 2 diabetes.

AIMS: Whereas homeostasis model assessment of insulin resistance (HOMA-IR), an easily measured but limited index of insulin resistance, has been shown to correlate with impairment of cardiac function in individuals without diabetes, the pathological relevance of insulin resistance to the development of cardiac dysfunction in individuals with type 2 diabetes has remained unclear. Here we investigated the relation between left ventricular (LV) function as assessed by echocardiography and insulin resistance as evaluated by hyperinsulinemic-euglycemic clamp analysis, the gold standard for measurement of this parameter, in individuals with type 2 diabetes. METHODS: This retrospective study included 34 individuals with type 2 diabetes who underwent both hyperinsulinemic-euglycemic clamp analysis and echocardiography. Both the insulin sensitivity index (ISI) as determined by glucose clamp analysis as well as HOMA-IR were determined as measures of insulin resistance. The ratio of the peak early- to late-diastolic mitral inflow velocities (E/A) and the LV ejection fraction (LVEF) were determined as measures of diastolic and systolic function, respectively. RESULTS: The ISI was significantly correlated with both the E/A ratio and LVEF (correlation coefficients of 0.480 and 0.360, respectively), whereas HOMA-IR was not correlated with either cardiac parameter. Multivariate analysis revealed that ISI was an independent predictor for both a high log [E/A] (P = 0.031) and a high LVEF (P = 0.045). CONCLUSIONS: Insulin resistance as evaluated by hyperinsulinemic-euglycemic clamp analysis may be causally related to LV diastolic and systolic dysfunction in individuals with type 2 diabetes.

Kruppel-like factor 15 regulates fuel switching between glucose and fatty acids in brown adipocytes.

AIMS/INTRODUCTION: Brown adipose tissue (BAT) utilizes large amounts of fuel for thermogenesis, but the mechanism by which fuel substrates are switched in response to changes in energy status is poorly understood. We have now investigated the role of Kruppel-like factor 15 (KLF15), a transcription factor expressed at a high level in adipose tissue, in the regulation of fuel utilization in BAT. MATERIALS AND METHODS: Depletion or overexpression of KLF15 in HB2 differentiated brown adipocytes was achieved by adenoviral infection. Glucose and fatty acid oxidation were measured with radioactive substrates, pyruvate dehydrogenase complex activity was determined with a colorimetric assay, and gene expression was examined by reverse transcription and real-time polymerase chain reaction analysis. RESULTS: Knockdown of KLF15 in HB2 cells attenuated fatty acid oxidation in association with downregulation of the expression of genes related to this process including Acox1 and Fatp1, whereas it increased glucose oxidation. Expression of the gene for pyruvate dehydrogenase kinase 4 (PDK4), a negative regulator of pyruvate dehydrogenase complex, was increased or decreased by KLF15 overexpression or knockdown, respectively, in HB2 cells, with these changes being accompanied by a respective decrease or increase in pyruvate dehydrogenase complex activity. Chromatin immunoprecipitation showed that Pdk4 is a direct target of KLF15 in HB2 cells. Finally, fasting increased expression of KLf15, Pdk4 and genes involved in fatty acid utilization in BAT of mice, whereas refeeding suppressed Klf15 and Pdk4 expression. CONCLUSIONS: Our results implicate KLF15 in the regulation of fuel switching between glucose and fatty acids in response to changes in energy status in BAT.

Analysis of time-dependent alterations of parameters related to erythrocytes after ipragliflozin initiation.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors often increase the hematocrit. It remains unclear whether this increase would be observed in all patients administered SGLT2 inhibitors, however. We therefore used the data from the previous study and investigated time-dependent alterations of various outcomes related to erythrocytes, erythropoiesis, and clinical outcome in type 2 diabetes subjects (n = 89) treated with ipragliflozin for 16 weeks. Among a total of 89 participants, 71 subjects (80.0% of total participants) showed the elevation of the hematocrit and 18 subjects (20.0% of total participants) did not at 16 weeks. Although the hematocrit levels at baseline were significantly lower in hematocrit-elevated group than non-elevated group, they reached the same levels 4 weeks after the onset of treatment. Binomial logistic regression analysis demonstrated that a lower baseline hematocrit level was related to the elevation of hematocrit at 16 weeks. Optimal cutoff hematocrit levels at baseline to predict hematocrit elevation were 46.9% (male) and 41.7% (female) in ROC analysis. Random intercept model analysis revealed the serum erythropoietin level increased in both hematocrit-elevated and non-elevated groups, whereas only the former group showed an increase in the percentage of reticulocytes during the first 4 weeks. These results suggest that the ipragliflozin-induced increase in hematocrit which is affected by the baseline hematocrit level is attributable to the responsiveness to, but not to the production of, erythropoietin. Collectively, Ht elevation observed in administration of SGLT2 inhibitors can result from erythropoietin-induced erythropoiesis, which is determined by the pre-treatment Ht level. Trial registration: This trial has been registered with University Hospital Medical Information Network Clinical Trial Registry (UMIN-CTR no. 000015478).

The t-SNAREs syntaxin4 and SNAP23 but not v-SNARE VAMP2 are indispensable to tether GLUT4 vesicles at the plasma membrane in adipocyte.

SNARE proteins (VAMP2, syntaxin4, and SNAP23) have been thought to play a key role in GLUT4 trafficking by mediating the tethering, docking and subsequent fusion of GLUT4-containing vesicles with the plasma membrane. The precise functions of these proteins have remained elusive, however. We have now shown that depletion of the vesicle SNARE (v-SNARE) VAMP2 by RNA interference in 3T3-L1 adipocytes inhibited the fusion of GLUT4 vesicles with the plasma membrane but did not affect tethering of the vesicles to the membrane. In contrast, depletion of the target SNAREs (t-SNAREs) syntaxin4 or SNAP23 resulted in impairment of GLUT4 vesicle tethering to the plasma membrane. Our results indicate that the t-SNAREs syntaxin4 and SNAP23 are indispensable for the tethering of GLUT4 vesicles to the plasma membrane, whereas the v-SNARE VAMP2 is not required for this step but is essential for the subsequent fusion event.

Sex difference in the association of obesity with personal or social background among urban residents in Japan.

The development of obesity is influenced by genetic and environmental factors and is associated with a variety of health problems. To gain insight into environmental factors that contribute to obesity, we analyzed the relation of personal or social background to obesity in men and women separately with the use of data from a community-based questionnaire survey of 5425 residents aged 20 to 64 years of Kobe, a representative large city in Japan. Obesity and normal weight were defined as a body mass index (BMI) of ≥25 and of ≥ 18.5 and < 25 kg/m2, respectively, according to the diagnostic criteria of the Japan Society for the Study of Obesity. The personal or social background factors examined included marital status, family structure, employment, household income, residence type, welfare enrollment, economic conditions of current life, educational level, extracurricular activity in school, living conditions at 15 years of age, and childhood adversity. We found that the prevalence of obesity was 27.2% and 10.6% in men and women, respectively. Among women, unmarried status, a low household income, welfare enrollment, difficult current economic conditions, a low educational level, and childhood adversity were associated with obesity, whereas none of the personal or social background factors examined were associated with obesity in men. Our results suggest that the development of obesity in women is strongly influenced by personal or social background, and such factors should be taken into consideration in the management of this condition in women.

Enhanced Release of Glucose Into the Intraluminal Space of the Intestine Associated With Metformin Treatment as Revealed by [18F]Fluorodeoxyglucose PET-MRI.

OBJECTIVE: Positron emission tomography (PET)-computed tomography has revealed that metformin promotes the intestinal accumulation of [18F]fluorodeoxyglucose (FDG), a nonmetabolizable glucose derivative. It has remained unknown, however, whether this accumulation occurs in the wall or intraluminal space of the intestine. We here addressed this question with the use of [18F]FDG PET-MRI, a recently developed imaging method with increased accuracy of registration and high soft-tissue contrast. RESEARCH DESIGN AND METHODS: Among 244 individuals with type 2 diabetes who underwent PET-MRI, we extracted 24 pairs of subjects matched for age, BMI, and HbA1c level who were receiving treatment with metformin (metformin group) or were not (control group). We evaluated accumulation of [18F]FDG in different portions of the intestine with both a visual scale and measurement of maximum standardized uptake value (SUVmax), and such accumulation within the intestinal wall or lumen was discriminated on the basis of SUVmax. RESULTS: SUVmax of the jejunum, ileum, and right or left hemicolon was greater in the metformin group than in the control group. [18F]FDG accumulation in the ileum and right or left hemicolon, as assessed with the visual scale, was also greater in the metformin group. SUVmax for the intraluminal space of the ileum and right or left hemicolon, but not that for the intestinal wall, was greater in the metformin group than in the control group. CONCLUSIONS: Metformin treatment was associated with increased accumulation of [18F]FDG in the intraluminal space of the intestine, suggesting that this drug promotes the transport of glucose from the circulation into stool.