Loss of renal SNX5 results in impaired IDE activity and insulin resistance in mice.

AIMS/HYPOTHESIS: We hypothesised that renal sorting nexin 5 (SNX5) regulates the insulin-degrading enzyme (IDE) and, thus, circulating insulin levels. We therefore studied the dynamic interaction between SNX5 and IDE in human renal proximal tubule cells (hRPTCs), as well as in rat and mouse kidneys. METHODS: The regulation of IDE by SNX5 expressed in the kidney was studied in vitro and in vivo. Snx5 or mock siRNA was added to immortalised hRPTCs (passage <20) in culture or selectively infused, via osmotic mini-pump, into the remnant kidney of uninephrectomised mice and rats. RESULTS: SNX5 co-localised with IDE at the plasma membrane and perinuclear area of hRPTCs and in the brush border membrane of proximal tubules of human, rat, and mouse kidneys. Insulin increased the co-localisation and co-immunoprecipitation of SNX5 and IDE in hRPTCs. Silencing SNX5 in hRPTCs decreased IDE expression and activity. Renal-selective silencing of Snx5 (SNX5 protein: 100 ± 25 vs 29 ± 10, p < 0.05 [% of control]) in C57Bl/6J mice decreased IDE protein (100 ± 13 vs 57 ± 6, p < 0.05 [% of control]) and urinary insulin excretion, impaired the responses to insulin and glucose, and increased blood insulin and glucose levels. Spontaneously hypertensive rats (SHRs) had increased blood insulin and glucose levels and decreased renal SNX5 (100 ± 27 vs 29 ± 6, p < 0.05 [% of control]) and IDE (100 ± 5 vs 75 ± 4, p < 0.05 [% of control]) proteins, compared with normotensive Wistar-Kyoto (WKY) rats. Kidney Snx5-depleted WKY rats also had increased blood insulin and glucose levels. The expression of SNX5 and IDE was decreased in RPTCs from SHRs and hypertensive humans compared with cells from normotensive volunteers, indicating a common cause for hyperinsulinaemia and hypertension. CONCLUSIONS/INTERPRETATION: Renal SNX5 positively regulates IDE expression and function. This study is the first to demonstrate the novel and crucial role of renal SNX5 in insulin and glucose metabolism.

Urinary Sodium-to-Potassium Ratio Tracks the Changes in Salt Intake during an Experimental Feeding Study Using Standardized Low-Salt and High-Salt Meals among Healthy Japanese Volunteers.

The Na/K ratio is considered to be a useful index, the monitoring of which allows an effective Na reduction and K increase, because practical methods (self-monitoring devices and reliable individual estimates from spot urine) are available for assessing these levels in individuals. An intervention trial for lowering the Na/K ratio has demonstrated that a reduction of the Na/K ratio mainly involved Na reduction, with only a small change in K. The present study aimed to clarify the relationship between dietary Na intake and the urinary Na/K molar ratio, using standardized low- and high-salt diets, with an equal dietary K intake, to determine the corresponding Na/K ratio. Fourteen healthy young adult volunteers ingested low-salt (3 g salt per day) and high-salt (20 g salt per day) meals for seven days each. Using a portable urinary Na/K meter, participants measured their spot urine at each voiding, and 24-h urine was collected on the last day of each diet period. On the last day of the unrestricted, low-salt, and high-salt diet periods, the group averages of the 24-h urine Na/K ratio were 4.2, 1.0, and 6.9, while the group averages of the daily mean spot urine Na/K ratio were 4.2, 1.1, and 6.6, respectively. The urinary Na/K ratio tracked changes in dietary salt intake, and reached a plateau approximately three days after each change in diet. Frequent monitoring of the spot urine Na/K ratio may help individuals adhere to an appropriate dietary Na intake.

Changes in Levels of Biomarkers Associated with Adipocyte Function and Insulin and Glucagon Kinetics During Treatment with Dapagliflozin Among Obese Type 2 Diabetes Mellitus Patients.

OBJECTIVES: This study aimed to investigate changes in levels of biomarkers associated with adipocyte function and insulin and glucagon kinetics after a meal tolerance test (MTT) during treatment with dapagliflozin among obese type 2 diabetes mellitus (T2DM) patients. METHODS: T2DM patients with hemoglobin A1c (HbA1c) levels >6.5 % and body mass index (BMI) >25 kg/m2 were treated with dapagliflozin 5 mg/day for at least 12 weeks. HbA1c, body weight, ketone bodies, adiponectin, plasminogen activator inhibitor-1 (PAI-1), and C-reactive protein (CRP) were measured before and after treatment with dapagliflozin. A subset of patients underwent an MTT. RESULTS: Of 27 participating patients (mean age 47.9 years; 17 males), five were drug-naive and 22 were treated with other antidiabetic agents, including insulin and glucagon-like peptide-1 (GLP-1) receptor agonists. Following treatment with dapagliflozin, HbA1c levels significantly improved (7.44 ± 0.56 to 6.70 ± 0.0.57 %; p < 0.01), body weight significantly decreased (90.9 ± 16.5 to 87.1 ± 15.9 kg; p < 0.01), ketone bodies increased, adiponectin significantly increased, and high-sensitivity CRP tended to decrease. During the MTT, blood glucose ΔAUC2 significantly decreased, glucagon ΔAUC2 increased, and immunoreactive insulin (IRI) did not change in 11 of 27 patients. CONCLUSION: Although ketone bodies increased significantly, adiponectin increased and high-sensivity CRP decreased significantly. These findings suggest that sodium-glucose cotransporter-2 (SGLT2) inhibitors may potentially improve adipocyte function in treating obese T2DM patients.

Association between health literacy and metabolic syndrome or healthy lifestyle characteristics among community-dwelling Japanese people.

BACKGROUND: Few studies have assessed the association between health literacy (HL) and healthy lifestyle characteristics among Japanese people, and reports on the association between HL and prevalence of metabolic syndrome are also scarce. METHODS: The present cross-sectional study included 1817 (781 men and 1036 women) Japanese individuals who participated in a medical health checkup at Bange Kosei General Hospital and Takada Kosei Hospital in Fukushima, Japan, from April 2013-2014. Information regarding HL and healthy lifestyle characteristics listed in Breslow's seven health practices was collected by self-administered questionnaire. RESULTS: In multivariate logistic analysis, higher HL (≥14) was positively associated with healthy lifestyle characteristics [odds ratio (OR) = 2.08, 95 % confidence interval (CI) = 1.33-3.23] and inversely associated with prevalence of metabolic syndrome (OR = 0.67, 95 % CI = 0.48-0.95) among men. Among HL items, the ability to make decisions based on health-related information was significantly associated with healthy lifestyle characteristics (OR = 2.04, 95 % CI = 1.34-3.10 for men, OR = 1.38, 95 % CI = 1.30-1.85 for women) and inversely associated with prevalence of metabolic syndrome (OR = 0.62, 95 % CI = 0.44-0.88 for men, OR = 0.68, 95 % CI = 0.49-0.95 for women) in both sexes. CONCLUSIONS: We found positive associations between HL and healthy lifestyle characteristics and an inverse association with prevalence of metabolic syndrome among men. Our findings also suggest that men and women are likely to engage in health-promoting behaviors and make decisions based on health-related information. These findings highlight the importance of comprehensive assessments, including HL, for health promotion in the community.

Human GRK4γ142V Variant Promotes Angiotensin II Type I Receptor-Mediated Hypertension via Renal Histone Deacetylase Type 1 Inhibition.

The influence of a single gene on the pathogenesis of essential hypertension may be difficult to ascertain, unless the gene interacts with other genes that are germane to blood pressure regulation. G-protein-coupled receptor kinase type 4 (GRK4) is one such gene. We have reported that the expression of its variant hGRK4γ(142V) in mice results in hypertension because of impaired dopamine D1 receptor. Signaling through dopamine D1 receptor and angiotensin II type I receptor (AT1R) reciprocally modulates renal sodium excretion and blood pressure. Here, we demonstrate the ability of the hGRK4γ(142V) to increase the expression and activity of the AT1R. We show that hGRK4γ(142V) phosphorylates histone deacetylase type 1 and promotes its nuclear export to the cytoplasm, resulting in increased AT1R expression and greater pressor response to angiotensin II. AT1R blockade and the deletion of the Agtr1a gene normalize the hypertension in hGRK4γ(142V) mice. These findings illustrate the unique role of GRK4 by targeting receptors with opposite physiological activity for the same goal of maintaining blood pressure homeostasis, and thus making the GRK4 a relevant therapeutic target to control blood pressure.

Association Between Serum Uric Acid Levels/Hyperuricemia and Hypertension Among 85,286 Japanese Workers.

This cross-sectional study from January 2012 to December 2012 aimed to examine the sex-specific association between serum uric acid (SUA) levels/hyperuricemia and hypertension among Japanese patients. SUA level, medical histories, and lifestyle-related items were collected from 85,286 of 136,770 participants. Among those with hyperuricemia, the median age was 46 years and 97% were men, which was significantly different than those without hyperurecemia (44 years and 56%, respectively; P<.01). Hyperuricemia was 1.79 times more likely in hypertensive men than normotensive men and almost six times more likely in hypertensive women (odds ratio=5.92 and adjusted odds ratio=1.33 for men and adjusted odds ratio=1.81 for women) after multivariate analysis. SUA quartiles positively correlated with systolic and diastolic blood pressures in both sexes. Hyperuricemia and SUA levels were significantly associated with hypertension in both sexes. These findings underscore the importance of maintaining normal SUA levels to manage and prevent hypertension. Better management of SUA as well as blood pressure may have potential in preventing future cardiovascular disorders.

Achievement of Target Blood Pressure Levels among Japanese Workers with Hypertension and Healthy Lifestyle Characteristics Associated with Therapeutic Failure.

BACKGROUND: Few studies have examined Japanese with regard to the achievement rates for target blood pressure levels, or the relationship between these rates and healthy lifestyle characteristics in patients with hypertension as defined by the newly established hypertension management guidelines (JSH2014). The aim of this study was to elucidate achievement rates and examine healthy lifestyle characteristics associated with achievement status among Japanese. METHODS: This cross-sectional study, conducted in January-December 2012, examined blood pressure control and healthy lifestyle characteristics in 8,001 Japanese workers with hypertension (mean age, 57.0 years; 78.8% were men) who participated in a workplace health checkup. Data were collected from workplace medical checkup records and participants' self-administered questionnaires. We divided into 5 groups [G1; young, middle-aged, and early-phase elderly patients (65-74 years old) without diabetes mellitus or chronic kidney disease (CKD) (<140/90 mmHg), G2; late-phase elderly patients (≥75 years old) without diabetes mellitus or CKD (<150/90 mmHg), G3; diabetic patients (<130/80 mmHg), G4; patients with CKD (<130/80 mmHg), and G5; patients with cerebrovascular and/or coronary artery diseases (<140/90 mmHg)] according to JSH2014. And then, achievement rates were calculated in each group. Multivariate analysis identified healthy lifestyle characteristics associated with "therapeutic failure" of target blood pressure. RESULTS: Target blood pressures were achieved by 60.2% of young, middle-aged, and early-phase elderly patients (G1), 71.4% of late-phase elderly patients (G2), 30.5% of diabetic patients (G3), 33.4% of those with chronic kidney disease (G4), and 66.0% of those with cerebrovascular and/or coronary artery diseases (G5). A body mass index of 18.5-24.9 and non-daily alcohol consumption were protective factors, and adequate sleep was found to contribute to therapeutic success. DISCUSSION: We found low achievement rates for treatment goals among patients with chronic kidney disease and diabetes mellitus. Maintaining an ideal body weight and adequate alcohol consumption may help with blood pressure control. Lifestyle modification may be necessary for better management of hypertension.

Effects of renal Na+/Ca2+ exchanger 1 inhibitor (SEA0400) treatment on electrolytes, renal function and hemodynamics in rats.

BACKGROUND: Na(+)/Ca(2+) exchanger 1 (NCX1) controls intracellular Ca(2+) concentration in various cell types. In the kidney, NCX1 is expressed mainly in the distal tubular basolateral membrane as well as in vascular smooth muscle. Tubular NCX1 is involved in Ca(2+) reabsorption, and NCX1 in renal arterioles may control intraglomerular pressure. However, the functions of renal NCX1 have not been studied in vivo. Therefore, this study examined the effects of renal NCX1 blockade on water and solute metabolism, renal function and blood pressure in rats. METHODS: Wistar-Kyoto rats were uninephrectomized, and an osmotic mini pump was implanted to infuse the remnant kidney cortex with a specific NCX1 inhibitor, SEA0400 (SEA), or vehicle for 7 days. RESULTS: Serum Ca(2+) concentration and urinary Ca(2+) excretion were similar between the vehicle- and SEA-treated groups. However, serum phosphate was significantly decreased by 8 % in the SEA group, with similar urinary phosphate excretion between the two groups. Systolic blood pressure was higher in the SEA group (117 ± 3 vs. 126 ± 1 mmHg, n = 9-11), with a 1.6-fold increase in plasma aldosterone concentration. However, SEA significantly reduced urinary protein excretion and the glomerular sectional area by 16 and 8 %, respectively. Similar experiment in spontaneously hypertensive rats produced different results. CONCLUSION: Renal SEA treatment reduced serum phosphate concentration, urinary protein and glomerular size with higher systemic blood pressure compared to control Wistar-Kyoto rats. Further study on renal NCX1 may be beneficial in delineating the pathophysiology of glomerular pressure control and calcium/phosphate regulations.

Association between lifestyle-related disorders and visceral fat mass in Japanese males: a hospital based cross-sectional study.

OBJECTIVE: This study aimed to examine the association between lifestyle-related disorders and visceral fat mass, and to estimate an appropriate cutoff value for visceral fat mass that correlated with body mass index (BMI) and waist circumference (WC). METHODS: This cross-sectional study was conducted between July 2012 and August 2013 at Bange Kosei General Hospital, in Fukushima, Japan. All study participants were adult males who had completed voluntary medical check-ups that included estimation of visceral fat mass by bioelectrical impedance analysis (BIA). Participants were without past histories of atherosclerotic complications or were not currently taking medications for lifestyle-related disorders. Multivariate analysis was performed to estimate the association between lifestyle-related disorders and quartiles of visceral fat mass. RESULTS: Of 536 total respondents, 442 were included in the analysis. Mean participant age was 56 years, and mean values of BMI, WC, and visceral fat mass were 24.1 kg/m(2), 85.9 cm, and 2.1 kg, respectively. Visceral fat mass ≥1.8 kg was positively associated with an increased prevalence of dyslipidemia, elevated blood pressure, and impaired glucose tolerance. Cutoff values that correlated with visceral fat mass (≥1.8 kg) were 85.3 cm for WC and 23.25 kg/m(2) for BMI. CONCLUSION: Visceral fat mass ≥1.8 kg was positively associated with lifestyle-related disorders and closely related to WC and BMI cutoff values used to diagnose obesity. BIA may be a useful method for assessing visceral fat mass, and these findings provide important evidence for the use of BIA in the early detection of central obesity for preventing lifestyle-related disorders.

Characteristic expressions of GABA receptors and GABA producing/transporting molecules in rat kidney.

Gamma-aminobutyric acid (GABA) is an important neurotransmitter, but recent reports have revealed the expression of GABAergic components in peripheral, non-neural tissues. GABA administration induces natriuresis and lowers blood pressure, suggesting renal GABA targets. However, systematic evaluation of renal GABAergic components has not been reported. In this study, kidney cortices of Wistar-Kyoto rats (WKY) were used to assay for messenger RNAs of GABA-related molecules using RT-PCR. In WKY kidney cortex, GABAA receptor subunits, α1, ß3, δ, ε and π, in addition to both types of GABAB receptors, R1 and R2, and GABAC receptor ρ1 and ρ2 subunit mRNAs were detected. Kidney cortex also expressed mRNAs of glutamate decarboxylase (GAD) 65, GAD67, 4-aminobutyrate aminotransferase and GABA transporter, GAT2. Western blot and/or immunohistochemistry were performed for those molecules detected by RT-PCR. By immunofluorescent observation, co-staining of α1, ß3, and π subunits was observed mainly on the apical side of cortical tubules, and immunoblot of kidney protein precipitated with π subunit antibody revealed α1 and ß3 subunit co-assembly. This is the first report of GABAA receptor π subunit in the kidney. In summary, unique set of GABA receptor subunits and subtypes were found in rat kidney cortex. As GABA producing enzymes, transporters and degrading enzyme were also detected, a possible existence of local renal GABAergic system with an autocrine/paracrine mechanism is suggested.

Dipeptidyl peptidase-4 inhibitor (vildagliptin) improves glycemic control after meal tolerance test by suppressing glucagon release.

AIM: We aimed to evaluate changes in insulin and glucagon secretion, as well as glucose levels, with a meal tolerance test (MTT) before and after 6 months of treatment with vildagliptin in a clinical setting. MATERIALS AND METHODS: Participants were 15 patients with uncontrolled type 2 diabetes mellitus (glycated hemoglobin [HbA1c] over 6.9% for more than 3 months). MTTs were conducted before and 6 months after addition of vildagliptin (50 mg twice daily [bid]). Blood samples were collected immediately before, and 1 and 2 h after the test meal for measurement of blood glucose concentration, immune-reactive insulin (IRI), and glucagon. HbA1c was measured at 6 months. RESULTS: Mean age of participants was 55.5 ± 2.8 years, and ten (66.7%) were male. Mean HbA1c significantly improved from 7.6 to 6.8% at 6 months after addition of vildagliptin. Blood glucose at 1 and 2 h after the test meal was significantly reduced after addition of vildagliptin, while the reduction in glucagon showed borderline significance and IRI showed no difference. In a comparison of blood glucose-related parameters between subgroups based on median glucose change in area under the curve during MTT (ΔAUC0-2h), glucagon ΔAUC0-2h was significantly lower in the group with more improved glucose levels (ΔAUC0-2h ≥65 mg/dL), but that of IRI did not differ. CONCLUSION: Suppression of glucagon release by vildagliptin may improve glycemic control without increasing insulin levels in patients with type 2 diabetes.

Association between control to target blood pressures and healthy lifestyle factors among Japanese hypertensive patients: longitudinal data analysis from Fukushima Research of Hypertension (FRESH).

OBJECTIVE: To determine success rates in controlling target blood pressures longitudinally by measuring several factors, including lifestyle characteristics associated with uncontrolled blood pressures for target treatment goals. METHODS AND PATIENTS: This prospective observational cohort study (September 2008-September 2010) collected information on blood pressure control status and healthy lifestyle factors listed in Breslow's seven health practices through medical records and self-administered questionnaires from 884 of the 1264 Japanese hypertensive patients initially registered in the FRESH study. Multivariate analysis adjusted for associated factors was performed to estimate the association between lifestyle change and "uncontrolled blood pressures" at the final follow-up survey. RESULTS: Median age and proportion of men were 73 years and 39.1%, respectively. All survey failure rates were 37.6% among non-elderly patients (<65 years of age) without diabetes mellitus or chronic kidney disease, and 35.0% among patients with these diseases or myocardial infarction. Maintaining a healthy lifestyle was a protective factor against uncontrolled blood pressures in multivariate analysis. Obesity and smoking status were associated with uncontrolled blood pressures, and exercise frequency was borderline significance. The number of participants with healthy responses for these factors remained relatively low during follow up. CONCLUSION: Our study revealed low rates of controlled blood pressures, especially in non-elderly patients without diabetes mellitus or chronic kidney disease, and patients with these diseases or myocardial infarction. Our data indicate the need to maintain a healthy lifestyle, in particular, ideal body weight and adequate exercise frequency, for better hypertension management according to treatment guidelines.

Early detection of colon cancer by amino acid profiling using AminoIndex Technology: a case report.

Most tumor markers have low detection rates for curable stages of cancer and are therefore not satisfactory for use in a healthy population. A new cancer risk calculation method, AminoIndex Cancer Screening (AICS), uses multiple plasma amino acid concentrations to calculate the risks for several cancers simultaneously and is suggested to have a high detection rate for early-stage cancers and a low false-positive rate for adenomas. Here, we describe a male patient with a family history of colorectal cancer who underwent AICS. He was judged as Rank C for colorectal cancer, which reportedly has a specificity of 95%, a sensitivity of 41%, and an estimated positive predictive value of 0.67%. He underwent colonoscopy for a secondary screening, which revealed a 10-mm adenoma-like lesion in the ascending colon, with a biopsy report of partial carcinoma. The tumor was endoscopically removed and diagnosed as carcinoma in situ (carcinoma in adenoma). This early detection method allowed complete resection of the carcinoma, and the patient is in remission. This is the first case in which a curable cancer was detected using AICS. With its high detection rate for early-stage cancers and its ease of use, this tool, which recently became available in Japan, may be beneficial for simultaneous screening of the general population for multiple cancers. Virtual slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2145080259887842.

Mini nutritional assessment as a useful method of predicting the development of pressure ulcers in elderly inpatients.

OBJECTIVES: To determine the usefulness of the Mini Nutritional Assessment (MNA) and plasma amino acid analysis in predicting the formation of pressure ulcers (PUs) in inpatients. DESIGN: Prospective, observational cohort study with a mean observation period of 62.2 ± 86.4 days. SETTING: Intermediate and acute care wards of a hospital in rural Japan. PARTICIPANTS: Inpatients with an average age of 85.0 ± 7.6 (N = 422). MEASUREMENTS: Mini Nutritional Assessment, Subjective Global Assessment (SGA), Braden Scale (PU prognostic score), PU formation, and biochemical analysis including plasma amino acid concentrations. RESULTS: PUs developed in 7.1% of participants. A MNA score of less than 8 was more sensitive than a rating of moderate or severe malnourishment on the SGA combined with a Braden Scale score of less than 15 in predicting future PUs. The area under the receiver operating characteristic curve (AUC) of the MNA was superior to that of the Braden Scale. The Braden Scale nutrition subscore had the lowest AUC of the six Braden Scale subscores. Individuals who developed PUs had significantly lower plasma arginine concentrations than those who did not. CONCLUSION: Mini Nutritional Assessment was able to predict the development of PUs. A MNA score of less than 8 performed better than the SGA, Braden Scale, and plasma arginine levels in predicting PU development. Although lower plasma arginine concentration at time of admission was associated with PU development, the AUC for arginine was not significantly different from 0.50. The findings from this prospective study support the use of nutritional assessment in inpatients to predict PU risk and target appropriate interventions.

Novel role of sorting nexin 5 in renal D(1) dopamine receptor trafficking and function: implications for hypertension.

The D1 dopamine receptor (D1R) is widely expressed in the kidney and plays a crucial role in blood pressure regulation. Although much is known about D1R desensitization, especially through G-protein-coupled receptor kinase 4 (GRK4), comparatively little is known about other aspects of D1R trafficking and the proteins involved in the process. We now report the discovery of a dynamic interaction between sorting nexin 5 (SNX5), a component of the mammalian retromer, and D1R in human renal epithelial cells. We show that internalization of agonist-activated D1R is regulated by both SNX5 and GRK4, and that SNX5 is critical to the recycling of the receptor to the plasma membrane. SNX5 depletion increases agonist-activated D1R phosphorylation (>50% at basal condition), prevents D1R internalization and cAMP response, and delays receptor recycling compared to mock siRNA-transfected controls. Moreover, renal restricted subcapsular infusion of Snx5-specific siRNA (vs. mock siRNA) decreases sodium excretion (Δ=-0.2±0.005 mEq/mg creatinine) and further elevates the systolic blood pressure (Δ=48±5 mm Hg) in spontaneously hypertensive rats, indicating that SNX5 depletion impairs renal D1R function. These studies demonstrate an essential role for SNX5 in regulating D1R function, which may have important diagnostic, prognostic, and therapeutic implications in the management of essential hypertension.

Effects of a high-sodium diet on renal tubule Ca2+ transporter and claudin expression in Wistar-Kyoto rats.

BACKGROUND: Urinary Ca2+ excretion increases with dietary NaCl. NaCl-induced calciuria may be associated with hypertension, urinary stone formation and osteoporosis, but its mechanism and long-term effects are not fully understood. This study examined alterations in the expressions of renal Ca2+ transporters, channels and claudins upon salt loading to better understand the mechanism of salt-induced urinary Ca2+ loss. METHODS: Eight-week old Wistar-Kyoto rats were fed either 0.3% or 8% NaCl diet for 8 weeks. Renal cortical expressions of Na+/Ca2+ exchanger 1 (NCX1), Ca2+ pump (PCMA1b), Ca2+ channel (TRPV5), calbindin-D28k, and claudins (CLDN-2, -7, -8, -16 and -19) were analyzed by quantitative PCR, western blot and/or immunohistochemistry. RESULTS: Fractional excretion of Ca2+ increased 6.0 fold with high-salt diet. Renal cortical claudin-2 protein decreased by approximately 20% with decreased immunological staining on tissue sections. Claudin-16 and -19 expressions were not altered. Renal cortical TRPV5, calbindin-D28k and NCX1 expressions increased 1.6, 1.5 and 1.2 fold, respectively. CONCLUSIONS: Chronic high-salt diet decreased claudin-2 protein and increased renal TRPV5, calbindin-D28k, and NCX1. Salt loading is known to reduce the proximal tubular reabsorption of both Na+ and Ca2+. The reduction in claudin-2 protein expression may be partly responsible for the reduced Ca2+ reabsorption in this segment. The concerted upregulation of more distal Ca2+-transporting molecules may be a physiological response to curtail the loss of Ca2+, although the magnitude of compensation does not seem adequate to bring the urinary Ca2+ excretion down to that of the normal-diet group.

High body mass index is an important risk factor for the development of type 2 diabetes.

OBJECTIVE: The aim of this study was to establish a causal relationship between excess body weight and the onset of diabetes in a retrospective cohort study. METHODS: This 10-year observational cohort study investigated 969 men and 585 women (23 to 80 years of age), who underwent voluntary complete medical check-ups and an annual 75-g oral glucose tolerance test (75 g-OGTT). Participants with fasting plasma glucose ≥126 mg/dL, 2-h glucose level in a 75 g-OGTT ≥200 mg/dL and/or received medical treatment for type 2 diabetes during the previous year were considered as new-onset diabetics. We assessed the independent contribution of increased BMI to the risk of developing type 2 diabetes with Cox proportional hazard model. RESULT: During the follow-up period, we diagnosed 86 men and 49 women with new-onset type 2 diabetes. In the Cox proportional hazards model, the risk of diabetes mellitus increased with increasing BMI, even after adjusting for age, sex, blood pressure, metabolic profiles, and insulin resistance. In the final model, setting BMI less than 25 as a reference group, the Hazard ratios for diabetes mellitus was 3.12 for those with a BMI of 25-27.4 and it was increased to 3.80 for participants with a BMI of 27.5 or higher. CONCLUSION: Overweight/obesity (high BMI) is an independent and dose-dependent risk factor for type 2 diabetes in overweight Japanese patients. Our results confirmed the usefulness of BMI as a classic parameter, and the importance of lifestyle modification and better management among people with overweight/obesity for prevention of type 2 diabetes mellitus.

Hypertension-Related Gene Polymorphisms of G-Protein-Coupled Receptor Kinase 4 Are Associated with NT-proBNP Concentration in Normotensive Healthy Adults.

G protein-coupled receptor kinase 4 (GRK4) with activating polymorphisms desensitize the natriuric renal tubular D1 dopamine receptor, and these GRK4 polymorphisms are strongly associated with salt sensitivity and hypertension. Meanwhile, N-terminal pro-B-type natriuretic peptide (NT-proBNP) may be useful in detecting slight volume expansion. However, relations between hypertension-related gene polymorphisms including GRK4 and cardiovascular indices such as NT-proBNP are not clear, especially in healthy subjects. Therefore, various hypertension-related polymorphisms and cardiovascular indices were analyzed in 97 normotensive, healthy Japanese adults. NT-proBNP levels were significantly higher in subjects with two or more GRK4 polymorphic alleles. Other hypertension-related gene polymorphisms, such as those of renin-angiotensin-aldosterone system genes, did not correlate with NT-proBNP. There was no significant association between any of the hypertension-related gene polymorphisms and central systolic blood pressure, cardioankle vascular index, augmentation index, plasma aldosterone concentration, or an oxidative stress marker, urinary 8-OHdG. Normotensive individuals with GRK4 polymorphisms show increased serum NT-proBNP concentration and may be at a greater risk of developing hypertension and cardiovascular disease.