Kazushige Hanaoka

Low-Grade Endotoxemia Contributes to Chronic Inflammation in Hemodialysis Patients: Examination With a Novel Lipopolysaccharide Detection Method

Chronic inflammation has recently been proposed to play a major role in the development of cardiovascular disease and mortality among advanced chronic kidney disease (CKD) patients; however, why advanced CKD promotes chronic inflammation is still unclear. We hypothesized that a very low level of plasma endotoxin (lipopolysaccharide [LPS]) contributes to chronic inflammation in advanced CKD patients. We measured the plasma LPS levels using a novel LPS detection method (ESP method, a method for endotoxin detection using laser scattering photometry) concurrently with serum C‐reactive protein (CRP) levels and various blood tests in 17 stable hemodialysis (HD) patients. As a result, the median LPS levels measured by the ESP method was 0.23 pg/mL (range, 0.01–3.89) (inflow, start of HD), 0.22 pg/mL (<0.01–9.97) (outflow, start of HD), 0.37 pg/mL (<0.01–7.42) (inflow, end of HD), and 1.07 pg/mL (<0.01–10.66) (dialysate), respectively; statistically significant differences were not detected between them. The predialysis median CRP level was 0.19 mg/dL (0.04–3.02). The logarithm of plasma LPS independently correlated with serum CRP (R = 0.595, P = 0.0103). In multiple (forward stepwise) regression analysis, in which CRP was determined to be the criterion variable, LPS (log), albumin, and the white blood cell count were adopted as independent explanatory variables (R = 0.401, −0.397 and 0.387, respectively). In conclusion, the present study revealed a significant relationship between LPS and CRP using the novel ESP method, and suggested that very low‐grade endotoxemia is contributing to systemic inflammation in HD patients.

The effect of eicosapentaenoic acid on renal function and volume in patients with ADPKD

BACKGROUND Soy protein ameliorates rat polycystic kidney disease with concomitant renal enrichment of omega3-polyunsaturated fatty acids. A study was conducted to examine the effects of eicosapentaenoic acids (EPA) on renal volume and function in patients with autosomal dominant polycystic kidney disease (ADPKD). METHODS Non-azotemic patients were randomized to either a control group (n = 20) or an EPA group (n = 21). EPA capsules (2.4 g/day) were administered in the EPA group for 2 years. Twenty-four hours of urine was collected for the creatinine clearance (Ccr) measurement every year. At baseline and 24 months, fatty acid compositions in erythrocytes were measured and computerized tomographies were obtained for calculation of renal volume by the modified ellipsoid and volumetric methods. RESULTS In the EPA group, the EPA concentration (1.80 +/- 0.99 versus 4.40 +/- 1.79 area%, P < 0.001) and the omega3/omega6 ratio in the erythrocyte increased, but docosahexaenoic acid (DHA) (6.76 +/- 1.19 versus 5.64 +/- 1.45 area%, P < 0.010) concentration decreased. Ccr decreased by 8.5 +/- 9.5 and 9.0 +/- 13.0 ml/min/1.73 m(2)/2 years in the control and EPA groups, respectively (NS). The increases in renal volume calculated by either method were not significantly different between the two groups. CONCLUSIONS A beneficial effect of EPA on renal function and kidney volume in ADPKD patients could not be confirmed in the present study. Administration of EPA with DHA supplementation and/or longer intervention might be necessary to demonstrate preventive effects of omega3-polyunsaturated fatty acids on progression of ADPKD.

A comprehensive search for mutations in the PKD1 and PKD2 in Japanese subjects with autosomal dominant polycystic kidney disease.

To elucidate the genotypic and phenotypic characteristics of autosomal dominant polycystic kidney disease (ADPKD) in Japanese populations, we performed a comprehensive search for mutations in PKD1 and PKD2 in 180 Japanese ADPKD patients from 161 unrelated families. We identified 112 (89 PKD1 and 23 PKD2) mutations within 135 families. Patients with PKD2 mutations account for 23.6% of all Japanese ADPKD families in this study. Seventy‐five out of the 112 mutations have not been reported previously. The estimated glomerular filtration rate (eGFR) decline was significantly faster in patients with PKD1 mutations than in those with PKD2 mutations (−3.25 and −2.08 ml min−1 year−1 for PKD1 and PKD2, respectively, p < 0.01). These results indicate that mutations within PKD1 and PKD2 can be linked to most of the cases of Japanese ADPKD, and the renal function decline was faster in patients with PKD1 mutations than in those with PKD2 mutations also in the Japanese ADPKD. We also found that PKD2 mutations were more frequent in Japanese ADPKD than that in European or American ADPKD.

Mechanisms of calcium transport across the basolateral membrane of the rabbit cortical thick ascending limb of Henle's loop

Although net Ca2+ absorption takes place in the thick ascending limb of Henles loop, detailed mechanisms are unknown. Because it has been reported that the Ca2+ entry step across the luminal membrane is mediated by Ca2+ channels inserted by stimulation with parathyroid hormone, we studied the mechanism of Ca2+ transport across the basolateral membrane of rabbit cortical thick ascending limb (CTAL) perfused in vitro by using microscopic fluorometry of cytosolic Ca2+ ([Ca2+]i) with fura-2. The resting [Ca2+]i in this segment was 49.8±4.5 nmol/l. Neither Na+ removal from the bathing solution nor addition of ouabain (0.1 mmol/l) to the bath increased [Ca2+]i, indicating that a Na+/Ca2+ exchanger in the basolateral membrane may not contribute in any major way to [Ca2+]i of CTAL. To confirm our technical accuracy, similar protocols were conducted in the connecting tubule, where the existence of a Na+/Ca2+ exchanger has been reported. In this segment, Na+ removal from the bath increased cell Ca2+ from 148.6 ±6.4 nmol/l to 647.6±132.0 nmol/l, confirming the documented fact. [Ca2+]i in the CTAL was markedly increased when 1 mmol/l NaCN was added to the bath in the absence of glucose. Calmodulin inhibitors (trifluoperazine or W-7) increased [Ca2+]i. When the bath pH was made alkaline, [Ca2+]i was also increased. This response was abolished when Ca2+ was eliminated from the bath, indicating that the Ca2+ entry across the basolateral membrane is dependent on bath pH. Increase in [Ca2+]i induced by an alkaline bath was inhibited by increased the bath K+ from 5 nmol/l to 50 mmol/l, suggesting that the Ca2+ entry system is voltage-dependent. However, the pH-dependent [Ca2+]i increase was unaffected by 0.1–10 μmol/l nicardipine in the bath. We conclude that Ca2+ transport across the basolateral membrane of CTAL is mediated by a pump-and-leak system of Ca2+ rather than a Na+/Ca2+ exchanger secondarily linked to a Na+, K+ pump.

Social functioning and socioeconomic changes after introduction of regular dialysis treatment and impact of dialysis modality: a multi-centre survey of Japanese patients.

Patient socialization and preservation of socioeconomic status are important patient‐centred outcomes for those who start dialysis, and retention of employment is a key enabler. This study examined the influence of dialysis inception and modality upon these outcomes in a contemporary Japanese cohort.

The Influence of a Single Nucleotide Polymorphism within CNDP1 on Susceptibility to Diabetic Nephropathy in Japanese Women with Type 2 Diabetes

Background Several linkage analyses have mapped a susceptibility locus for diabetic nephropathy to chromosome 18q22–23, and polymorphisms within the carnosine dipeptidase 1 gene (CNDP1), located on 18q22.3, have been shown to be associated with diabetic nephropathy in European subjects with type 2 diabetes. However, the association of this locus with diabetic nephropathy has not been evaluated in the Japanese population. In this study, we examined the association of polymorphisms within the CNDP1/CNDP 2 locus with diabetic nephropathy in Japanese subjects with type 2 diabetes. Methodology/Principal Findings We genotyped a leucine repeat polymorphism (D18S880) that is within CNDP1 along with 29 single nucleotide polymorphisms (SNPs) in the CNDP1/CNDP2 locus for 2,740 Japanese subjects with type 2 diabetes (1,205 nephropathy cases with overt nephropathy or with end-stage renal disease [ESRD], and 1,535 controls with normoalbuminuria). The association of each polymorphism with diabetic nephropathy was analysed by performing logistic regression analysis. We did not observe any association between D18S880 and diabetic nephropathy in Japanese subjects with type 2 diabetes. None of the 29 SNPs within the CNDP1/CNDP2 locus were associated with diabetic nephropathy, but a subsequent sex-stratified analysis revealed that 1 SNP in CNDP1 was nominally associated with diabetic nephropathy in women (rs12604675-A; p = 0.005, odds ratio [OR] = 1.76, 95% confidence interval [CI], 1.19−2.61). Rs12604675 was associated with overt proteinuria (p = 0.002, OR = 2.18, 95% CI, 1.32−3.60), but not with ESRD in Japanese women with type 2 diabetes. Conclusions/Significance Rs12604675-A in CNDP1 may confer susceptibility to overt proteinuria in Japanese women with type 2 diabetes.

Angiotensin receptor blocker (ARB)–diuretic versus ARB–calcium channel blocker combination therapy for hypertension uncontrolled by ARB monotherapy

Abstract Diuretics or calcium channel blockers (CCBs) are used concomitantly with an angiotensin II receptor blocker (ARB). However, it is not established which ARB-based combination therapy is the most effective and safe. This prospective randomized open-label study compared the efficacy and safety of a fixed-dose tablet of losartan (LST)–hydrochlorothiazide (HCTZ) (n = 99) and LST–amlodipine (AML) (n = 77) in Japanese patients whose hypertension was uncontrolled by ARB monotherapy. Blood pressure changed similarly over the 12-month study period. Only LST–HCTZ significantly increased serum uric acid (SUA) in patients with low baseline SUA (<5.6 mg/dL) but not in patients with high baseline SUA.

Evidence-based clinical practice guidelines for polycystic kidney disease 2014.

ADPKD is the most common hereditary cystic kidney disease. ADPKD is characterized by the progressive development of fluid-filled cysts derived from renal tubular epithelial cells and the development of disorders in several organs. Bilateral renal cysts enlarge progressively, gradually compromising renal function, and finally, end-stage renal disease (ESRD) requiring renal replacement therapy occurs in approximately 50 % of patients by the age of 60 years. The pattern of transmission in ADPKD is autosomal dominant inheritance. A male or female with a mutant allele develops the disease. In case that both parents are unaffected, disease in the offspring results from new mutation. ADPKD is caused by a germ line mutation in PKD1 (16p13.3)(85 % of cases) or PKD2 (4q21)(15 % of cases).

Characteristics of spontaneous calcium oscillations in renal tubular epithelial cells

BackgroundThe kidney is a major organ involved in calcium (Ca2+) metabolism. Ca2+ is transported through renal tubular epithelial cells. The intracellular free calcium concentration ([Ca2+]i) is tightly controlled at a low concentration, but transient increases and oscillations in [Ca2+]i are induced by various conditions. In this study, we investigated the mechanisms underlying the spontaneous [Ca2+]i oscillations observed in MDCK cells.Methods[Ca2+]i was monitored in fura-2-loaded Madin-Darby canine kidney (MDCK) cells using a calcium imaging system. We investigated the mechanism by which [Ca2+]i changed by applying drugs or by changing the extracellular Ca2+ concentration.ResultsSpontaneous [Ca2+]i oscillations occurred in MDCK cells. The oscillations occurred irregularly and were not transmitted to neighboring cells. Spontaneous [Ca2+]i oscillations in MDCK cells were initiated by Ca2+ release from ryanodine/IP3-sensitive intracellular calcium stores, and their frequency was largely unaffected by the extracellular Ca2+ concentration. Moreover, the frequency of the oscillations was increased by extracellular nucleotide, but was decreased when the nucleotides were removed.ConclusionsOur study suggested that [Ca2+]i release from ryanodine/IP3-sensitive intracellular calcium stores mediates spontaneous [Ca2+]i oscillations in MDCK cells. Calcium oscillations may be associated with the function of the renal tubular epithelial cells.

A case of renal sarcoidosis: a special reference to calcium metabolism as a diagnostic and the therapeutic implications.

Sarcoidosis is a systemic granulomatous disease of unknown etiology and is associated with a wide variety of renal disorders including nephrolithiasis, hypercalciuria, hypercalcemia, nephrocalcinosis, tubular defect, glomerulonephritis, and granulomatous interstitial nephritis. We report a case of renal sarcoidosis in which we could not detect any evidence of extrarenal involvements that was diagnosed by renal biopsy and abnormal calcium metabolism incompatible with chronic renal insufficiency. On laboratory findings, decreased creatinine clearance, proteinuria, hypercalcemia, hypercalciuria, and mildly elevated serum angiotensin-converting enzyme (ACE) were seen. Serum intact parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D (1,α-25 vit D) were lower and higher than normal range, respectively, whereas the patient was already in chronic renal insufficiency. He was treated with oral corticosteroid. Serum ACE tended to fall, and 1,α-25 vit D level decreased with substantial fall of serum calcium and daily calcium excretion. In contrast, intact PTH increased slowly in accordance with a fall of serum calcium compatible with the level of renal impairment. Creatinine clearance and daily excretion of protein improved. The case reported here may propose that serial measurement of serum level of 1,α-25 vit D, calcium level, and magnitude of daily calcium excretion into urine is a simple and meaningful tool to detect the therapeutic response in sarcoidosis with abnormal calcium metabolism.