Inhibition of tissue-nonspecific alkaline phosphatase protects against medial arterial calcification and improves survival probability in the CKD-MBD mouse model.

Medial arterial calcification (MAC) is a major complication of chronic kidney disease (CKD) and an indicator of poor prognosis. Aortic overexpression of tissue-nonspecific alkaline phosphatase (TNAP) accelerates MAC formation. The present study aimed to assess whether a TNAP inhibitor, SBI-425, protects against MAC and improves survival probability in a CKD-mineral and bone disorder (MBD) mouse model. CKD-MBD mice were divided in three groups: vehicle, SBI-10, and SBI-30. They were fed a 0.2% adenine and 0.8% phosphorus diet from 14 to 20 weeks of age to induce CKD, followed by a high-phosphorus (0.2% adenine and 1.8% phosphorus) diet for another 6 weeks. At 14-20 weeks of age, mice in the SBI-10 and SBI-30 groups were given 10 and 30 mg/kg SBI-425 by gavage once a day, respectively, while vehicle-group mice were given distilled water as vehicle. Control mice were fed a standard chow (0.8% phosphorus) between the ages of 8 and 20 weeks. Computed tomography imaging, histology, and aortic tissue calcium content revealed that, compared to vehicle animals, SBI-425 nearly halted the formation of MAC. Mice in the control, SBI-10 and SBI-30 groups exhibited 100% survival, which was significantly better than vehicle-treated mice (57.1%). Aortic mRNA expression of Alpl, encoding TNAP, as well as plasma and aortic tissue TNAP activity, were suppressed by SBI-425 administration, whereas plasma pyrophosphate increased. We conclude that a TNAP inhibitor successfully protected the vasculature from MAC and improved survival rate in a mouse CKD-MBD model, without causing any adverse effects on normal skeletal formation and residual renal function. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Risk Factors for Acute Kidney Injury and Chronic Kidney Disease following Allogeneic Hematopoietic Stem Cell Transplantation for Hematopoietic Malignancies.

BACKGROUND: Acute kidney injury (AKI) and chronic kidney disease (CKD) are considered common complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT). OBJECTIVES AND METHOD: In this study, 114 patients who had undergone allo-HSCT were retrospectively analyzed to investigate the risk factors for onset of posttransplant AKI and CKD as defined by the new Kidney Disease Improving Global Outcomes criteria. RESULTS: Seventy-four patients (64.9%) developed AKI and 25 (21.9%) developed CKD. The multivariate analysis showed that the risk factors for developing stage 1 or higher AKI were age ≥46 years at the time of transplant (p = 0.001) and use of ≥3 nephrotoxic drugs (p = 0.036). For CKD, the associated risk factors were disease status other than complete remission at the time of transplantation (p = 0.018) and onset of AKI after transplant (p = 0.035). The 5-year overall survival (OS) was significantly reduced by development of AKI (p < 0.001), but not CKD. Posttransplant AKI significantly increased the 5-year nonrelapse mortality (p < 0.001), whereas posttransplant CKD showed an increasing tendency, but the difference was not significant. CONCLUSIONS: Posttransplant AKI impacts OS, significantly increases the risk of CKD, and is significantly associated with disseminated intravascular coagulation and use of ˃3 nephrotoxic drugs.

Metabolomics analysis elucidates unique influences on purine / pyrimidine metabolism by xanthine oxidoreductase inhibitors in a rat model of renal ischemia-reperfusion injury.

BACKGROUND: Clinically applied as anti-gout drugs, xanthine oxidoreductase (XOR) inhibitors, especially the potent, selective, non-purine-analog XOR inhibitors febuxostat and topiroxostat, exert organ-protective effects. We tested the hypothesis that preservation of tissue concentrations of high-energy phosphates, such as ATP and ADP, contributes to organ-protective effects through CE-TOFMS metabolomics. METHODS: Rats were subjected to 30 min of renal ischemia-reperfusion (I/R) injury 60 min after oral administration of 10 mg/kg febuxostat, 10 mg/kg topiroxostat, 50 mg/kg allopurinol, or vehicle. RESULTS: In non-purine-analog XOR inhibitor-treated groups, renal concentrations of high-energy phosphates were greater before and after I/R injury, and renal adenine compounds were less depleted by I/R injury than in the vehicle and allopurinol groups. These findings were well in accordance with the proposed hypothesis that the recomposition of high-energy phosphates is promoted by non-purine-analog XOR inhibitors via the salvage pathway through blockade of hypoxanthine catabolism, whereas non-specific inhibitory effects of allopurinol on purine/pyrimidine enzymes impede this re-synthesis process. CONCLUSIONS: This metabolic approach shed light on the physiology of the organ-protective effects of XOR inhibitors.

Evaluation of 8-week glecaprevir/pibrentasvir treatment in direct-acting antiviral-naïve noncirrhotic HCV genotype 1 and 2infected patients in a real-world setting in Japan.

Based on high efficacy and safety demonstrated in clinical trials, treatment with glecaprevir/pibrentasvir (G/P) for 8 weeks is recommended for hepatitis C virus (HCV)-infected patients who are direct-acting antiviral (DAA) naïve, genotype 1 or 2, and noncirrhotic. The aim of this study was to validate real-world experience with 8-week G/P treatment in Japan. We conducted a prospective observational cohort study in 554 patients who underwent 8-week treatment from among 1,022 patients who initiated G/P therapy. The majority (54.5%) were male, with a median age of 66 years, and HCV genotype distribution was genotype 1, 43.8%; genotype 2, 55.3%; and mixed subtype, 0.9%. Overall, the sustained virologic response rate at 12 weeks (SVR12) was 92.8% (530/571) in the intention-to-treat population and 99.3% (526/530) in the per-protocol population. The SVR12 rates by subgroups were as follows: subtype 1a, 100% (6/6); 1b, 100% (189/189); 2a, 99.3% (150/151); 2b, 99.0% (103/104); and mixed subtype, 50% (2/4). Among four patients with virologic failure following 8-week treatment with G/P, none had baseline polymorphisms or treatment-emergent amino acid substitutions in NS3. However, 2 of 4 patients with virologic failure had treatment-emergent amino acid substitutions in NS5A. Adverse events (AEs) were reported in 21.5% of patients and 1.2% of patients discontinued due to drug-related AEs. In conclusion, G/P treatment for 8 weeks was safe and effective for DAA-naïve noncirrhotic genotype 1 or 2 patients in a real-world clinical setting in Japan.

Influence of renal ischaemia-reperfusion injury on renal neutrophil gelatinase-associated lipocalin receptor (24p3R) in rats.

The neutrophil gelatinase-associated lipocalin (NGAL) receptor (24p3R) is expressed in distal nephron and contributes to the endocytosis of NGAL in urine. This study was undertaken to evaluate an influence of renal ischaemia-reperfusion injury on 24p3R. Unilateral renal pedicle was clamped for 0, 10, 20, 30, or 45 minutes in male Wistar rats. Urine was collected for 24 hours after reperfusion, and ischaemic kidney and blood sample were obtained. Apparent histological injury in the ischaemic kidney was detected in the 30 and 45 minutes-treated groups. Urinary NGAL excretion elevated in rats with renal ischaemia for more than 20 minutes, while serum creatinine increased in rats for more than 30 minutes of ischaemia. Renal protein expression of NGAL did not significantly change. Renal mRNA expressions of megalin and cubilin, which are expressed at renal proximal tubules and uptake NGAL, decreased in animals with renal ischaemia for more than 20 minutes. Renal protein expression of 24p3R, which is expressed at renal distal tubules and uptake NGAL, decreased in rats with renal ischaemia for 45 min. This study showed for the first time that renal 24p3R decreased in response to renal ischaemia. As relatively longer renal ischaemia (45 minutes) decreased renal 24p3R protein and increased urinary NGAL excretion, the down-regulation of 24p3R protein might contribute to the elevated urinary excretion of NGAL in rats with unilateral ischaemia-reperfusion injury.

Kinetics of carnitine concentration after switching from oral administration to intravenous injection in hemodialysis patients.

Carnitine has high dialyzability and is often deficient in dialysis patients. This deficiency is treated by either intravenous (IV) or oral supplementation of carnitine. In this study, the mode of carnitine administration was changed from oral to IV in 17 hemodialysis (HD) patients, and the treatment was discontinued after 1 year. We found that the levels of total carnitine (TC), free-carnitine (FC), and acyl-carnitine (AC) significantly increased after 3 months of switching to IV administration (p < .05). After discontinuation of carnitine administration, the TC, FC, and AC levels decreased before dialysis. The average FC value was maintained at the normal levels until 9 months, but fell below the normal values when measured at the 12th month of discontinuation. In conclusion, carnitine was maintained at significantly high levels despite the smaller dose by IV infusion as compared with that by oral administration. We therefore suggest that our results be considered while determining both the carnitine administration route and the administration period in dialysis patients under clinical settings.

High urinary albumin/creatinine ratio at admission predicts poor functional outcome in patients with acute ischaemic stroke.

AIM: Albuminuria and a low estimated glomerular filtration rate (eGFR) are widely recognized indices of kidney dysfunction and have been linked to cardiovascular events, including stroke. We evaluated albuminuria, measured using the urinary albumin/creatinine ratio (UACR), and the eGFR in the acute phase of ischaemic stroke, and investigated the clinical characteristics of ischaemic stroke patients with and those without kidney dysfunction. METHODS: The study included 422 consecutive patients admitted between June 2010 and May 2012. General blood and urine examinations were performed at admission. Kidney dysfunction was defined as a low eGFR (<60 mL/min per 1.73 m2 ), high albuminuria (≥30 mg/g creatinine), or both. Neurological severity was evaluated using the National Institutes of Health Stroke Scale (NIHSS) at admission and the modified Rankin scale (mRS) at discharge. A poor outcome was defined as a mRS score of 3-5 or death. The impacts of the eGFR and UACR on outcomes at discharge were evaluated using multiple logistic regression analysis. RESULTS: Kidney dysfunction was diagnosed in 278 of the 422 patients (65.9%). The eGFR was significantly lower and UACR was significantly higher in patients with a poor outcome than in those with a good outcome. In multivariate analyses performed after adjusting for confounding factors, UACR >31.2 mg/g creatinine (OR, 2.58; 95% CI, 1.52-4.43; P = 0.0005) was independently associated with a poor outcome, while a low eGFR was not associated. CONCLUSIONS: A high UACR at admission may predict a poor outcome at discharge in patients with acute ischaemic stroke.

A low initial serum sodium level is associated with an increased risk of overcorrection in patients with chronic profound hyponatremia: a retrospective cohort analysis.

BACKGROUND: Even with abundant evidence for osmotic demyelination in patients with hyponatremia, the risk factors for overcorrection have not been fully investigated. Therefore the purpose of this study is to clarify the risks for overcorrection during the treatment of chronic profound hyponatremia. METHODS: This is a single-center retrospective observational study. We enrolled 56 adult patients with a serum sodium (SNa) concentration of ≤125 mEq/L who were treated in an intensive care unit by nephrologists using a locally developed, fixed treatment algorithm between February 2012 and April 2014. The impact of patient parameters on the incidence of overcorrection was estimated using univariable and multivariable logistic regression models. Overcorrection was defined as an increase of SNa by >10 mEq/L and >18 mEq/L during the first 24 and 48 h, respectively. RESULTS: The median age was 78 years, 48.2% were male, and 94.6% of the patients presented with symptoms associated with hyponatremia. The initial median SNa was 115 mEq/L (quartile, 111-119 mEq/L). A total of 11 (19.6%) patients met the criteria for overcorrection with 9 (16.0%) occurring at 24 h, 6 (10.7%) at 48 h, and 4 (7.1%) at both 24 and 48 h. However, none of these patients developed osmotic demyelination. Primary polydipsia, initial SNa, and early urine output were the significant risk factors for overcorrection on univariable analysis. Multivariable analysis revealed that the initial SNa had a statistically significant impact on the incidence of overcorrection with an adjusted odds ratio of 0.84 (95% confidence interval, 0.70-0.98; p = 0.037) for every 1 mEq/L increase. Additionaly, the increase in SNa during the first 4 h and early urine output were significantly higher in patients with overcorrection than in those without (p = 0.001 and 0.005, respectively). CONCLUSIONS: An initial low level of SNa was associated with an increased risk of overcorrection in patients with profound hyponatremia. In this regard, the rapid increase in SNa during the first 4 h may play an important role.

Warfarin use and incidence of stroke in Japanese hemodialysis patients with atrial fibrillation.

Atrial fibrillation (AF) is one of the major risk factor for ischemic stroke, and oral anticoagulation is generally indicated for prevention of stroke. However, the utility of oral anticoagulation for AF in dialysis patients remains controversial. In this single-center, retrospective, observational study, data from 1120 patients on maintenance hemodialysis were analyzed. Baseline medical data were collected from dialysis records including age, gender, the cause of end-stage renal disease, dialysis vintage, and comorbidities. We evaluated outcomes including stroke, major hemorrhage, and death. A total of 106 (11.4 %) patients had AF. After exclusion criteria were applied, 84 patients had analyzable data. Warfarin was prescribed in 30 (35.7 %) of these patients. The remaining 54 patients were classified as the non-warfarin group. CHADS2 score was not significantly different between the warfarin and non-warfarin group. During the mean 47 months of follow up, 7 strokes occurred. However, warfarin use was not associated with the risk for stroke [hazard ratio (HR) 1.07; 95 % confidence interval (CI) 0.20-5.74]. Kaplan-Meier analysis showed no statistically significant difference in the overall survival, stroke-free survival or bleeding-free survival between the warfarin and non-warfarin group. AF is common in Japanese dialysis patients. Despite a certain prevalence of oral anticoagulation, the present study demonstrated neither beneficial nor detrimental effects. A large randomized controlled trial should be considered.

[Effects of long-acting insulin degludec on type 2 diabetic hemodialysis patients with poor glycemic control].

BACKGROUND: The ratio of elderly complicated diabetes mellitus (DM) to all hemodialysis (HD) patients has increased. The number of elderly DM patients with poor glycemic control has also increased due to complications, such as dementia. By means of appropriate glycemic control, the risk of cardiovascular disease might decrease among diabetic HD patients, and improvement of their prognosis could be expected. When glycemic control is poor when treating diabetic HD patients with oral hypoglycemic agents, insulin treatment could be indicated. METHODS: Using continuous glucose monitor (CGM), we evaluated the differences in glucose variability of 3 type 2 diabetic HD patients with poor glycemic control when switching from insulin glargine to degludec. RESULTS: Case 1 was a 72-year-old man with poor dietary self-management, whose glycated albumin (GA) level was 27%, and was administered lispro 6-6-6 U plus glargine 8 U daily. He was switched from glargine to degludec 6 U daily. Eight weeks later, his glycemic control improved as seen in his GA level (19%) and CGM. Case 2 was an 84-year-old solitary woman with dementia. Her GA level was 28.4%, and she was administered glargine 8 U (after HD, 3 times/week). She was switched from glargine to degludec 6 U (after HD, 3 times/week). Her glycemic control improved as seen in her GA level (25.1%) and CGM thereafter. Case 3 was a 65-year-old solitary man with liver cirrhosis and chronic pancreatitis. His GA level was 26.6%, and he was administered glargine 8 U (every day). He was switched from glargine to degludec 12 U (after HD, 3 times/week). His glycemic control improved as seen in his GA level (21.3%) and CGM thereafter. CONCLUSIONS: These results suggest that degludec is more effective than glargine in improving glycemic control and reducing the insulin dose in type 2 diabetic HD patients.

ABCA8 stimulates sphingomyelin production in oligodendrocytes.

Members of the ABCA (ATP-binding cassette subfamily A) family are characterized by their ability to transport lipids across cellular membranes and regulate lipid homoeostasis in the brain and peripheral tissues. ABCA8 is a little-known member of this subfamily that was originally cloned from human brain libraries and has no known function. In an effort to elucidate the role of ABCA8 in the brain we first undertook a comprehensive analysis of its expression in the human brain. ABCA8 was differentially expressed in multiple regions of adult human brains with significantly higher expression in oligodendrocyte-enriched white matter regions compared with grey matter cortical regions. We then assessed the impact of ABCA8 on sphingomyelin production in oligodendrocyte and showed that ABCA8 was able to significantly stimulate both sphingomyelin synthase 1 expression and sphingomyelin production. Furthermore, ABCA8 expression in the prefrontal cortex across the human life span correlated strongly with age-associated myelination, and the myelinating gene p25α was significantly up-regulated with ABCA8. The present study represents the first extensive expression and functional study of ABCA8 in the human brain and the results strongly suggest that ABCA8 regulates lipid metabolism in oligodendrocytes and potentially plays a role in myelin formation and maintenance.

Febuxostat for treating allopurinol-resistant hyperuricemia in patients with chronic kidney disease.

BACKGROUND: Availability of the novel xanthine oxidase inhibitor febuxostat, which has multiple excretion pathways, enables investigation of the significance of serum uric acid control on renal function in patients with chronic kidney disease (CKD). METHODS: This was an exploratory, retrospective, observational study conducted at a single Japanese center. Serum uric acid concentrations and serum creatinine levels in the 6 months before and after the start of febuxostat treatment were collected for CKD patients switched from allopurinol after failing to achieve serum uric acid concentrations ≤6.0 mg/dL. RESULTS: Evaluable data were available for 60 patients, 67% of whom had advanced CKD (eGFR <30 mL/min/1.73 m2). Mean dose of febuxostat was 15.9 (± 8) mg/day. Mean serum uric acid concentration decreased from 8.4 (±1.4) mg/dL at baseline to 6.2 (±1.2) mg/dL at 6 months; 47.5% of patients achieved a level ≤6.0 mg/dL. The change from baseline in eGFR was positive at all time points during febuxostat treatment and the increase of 2.3 (±5.6) mL/min/1.73 m2 at 6 months was significant (p = 0.0027). Whereas the eGFR slope was negative during allopurinol treatment, it became positive after the switch to febuxostat. The change in eGFR slope before and after febuxostat treatment was significant for all patients (p < 0.01), for male patients (p < 0.05), and for patients with a baseline eGFR of <15 mL/min/1.73 m2 (p < 0.05). CONCLUSIONS: In patients with CKD, febuxostat reduces serum uric acid concentrations effectively and may suppress the progressive decline in renal function.

[Diuretic agent].

This clause explains a diuretic as an antihypertensive agent. A diuretic is a medicine used as a first-line agent also in the present. As an antihypertensive agent, a thiazide-type diuretic drug is used in many cases. Use of furosemide is not recommended other than a chronic kidney disease patient. Considering future medical economics, it is desirable to use a diuretic drug positively.

The effects of tolvaptan on patients with severe chronic kidney disease complicated by congestive heart failure.

BACKGROUND: Tolvaptan, a diuretic with a new mechanism of action, selectively binds to the vasopressin V2 receptor and inhibits reabsorption of water. Its effect on heart failure is proven, but its benefit for patients with chronic kidney disease (CKD) has not been not confirmed. In this study, we examined the effect of tolvaptan on patients with severe CKD. METHODS: We analyzed patients with stage 4 or higher CKD who had congestive heart failure that was resistant to existing diuretics. The patients were administered an initial tolvaptan dose of 7.5 mg/day. We assumed urine volume and urine osmolality to be the main effective endpoint and recorded free water clearance, serum osmolality, serum creatinine (Cr) level, and adverse events. RESULTS: There was no instance of clinically significant hypernatremia. The urine volume increased significantly (P < 0.0001), as did the urine osmolality (P = 0.0053). Free water clearance showed a tendency to increase, although the difference was not statistically significant. The serum creatinine level did not change significantly, and there was no clear effect on renal function. However, in patients with stage 5 CKD, the serum creatinine level decreased significantly (n = 5, P = 0.0435). There were no adverse events. CONCLUSION: We confirmed that tolvaptan has a diuretic effect in patients with both severe CKD and congestive heart failure without causing either clinically significant hypernatremia or an adverse effect on renal function. Tolvaptan is an effective diuretic for patients with CKD.

Claudin-2-deficient mice are defective in the leaky and cation-selective paracellular permeability properties of renal proximal tubules.

Claudin-2 is highly expressed in tight junctions of mouse renal proximal tubules, which possess a leaky epithelium whose unique permeability properties underlie their high rate of NaCl reabsorption. To investigate the role of claudin-2 in paracellular NaCl transport in this nephron segment, we generated knockout mice lacking claudin-2 (Cldn2(-/-)). The Cldn2(-/-) mice displayed normal appearance, activity, growth, and behavior. Light microscopy revealed no gross histological abnormalities in the Cldn2(-/-) kidney. Ultrathin section and freeze-fracture replica electron microscopy revealed that, similar to those of wild types, the proximal tubules of Cldn2(-/-) mice were characterized by poorly developed tight junctions with one or two continuous tight junction strands. In contrast, studies in isolated, perfused S2 segments of proximal tubules showed that net transepithelial reabsorption of Na(+), Cl(-), and water was significantly decreased in Cldn2(-/-) mice and that there was an increase in paracellular shunt resistance without affecting the apical or basolateral membrane resistances. Moreover, deletion of claudin-2 caused a loss of cation (Na(+)) selectivity and therefore relative anion (Cl(-)) selectivity in the proximal tubule paracellular pathway. With free access to water and food, fractional Na(+) and Cl(-) excretions in Cldn2(-/-) mice were similar to those in wild types, but both were greater in Cldn2(-/-) mice after i.v. administration of 2% NaCl. We conclude that claudin-2 constitutes leaky and cation (Na(+))-selective paracellular channels within tight junctions of mouse proximal tubules.

The mitochondrial SIRT1-PGC-1α axis in podocyte injury.

Dysfunction of mitochondria in podocytes is believed to be a trigger of injury and contributes to progressive glomerular sclerosis; however, the mechanisms had not been fully understood. Yuan et al. report involvement of SIRT1 (a homolog of the life-extending gene sir2 in mammals) and PPAR-γ coactivator 1α, a major regulator of oxidative metabolism, in mitochondria during podocyte injury. This information will be important in exploration of the mechanisms and future treatment of glomerular sclerosis.

Role of matrix metalloproteinase-2 in recovery after tubular damage in acute kidney injury in mice.

BACKGROUND/AIMS: Matrix metalloproteinases (MMPs) are zinc endopeptidases that degrade extracellular matrix and are involved in the pathogenesis of ischemic damage in acute kidney injury (AKI). In the present study, we analyzed the role of MMP-2 in the repair process in ischemic AKI. METHODS: AKI was induced in MMP-2 wild-type (MMP-2(+/+)) and MMP-2-deficient (MMP-2(-/-)) mice by 90-min renal artery clamping followed by reperfusion. Renal histology and the activity and distribution of MMP-2 were examined from day 1 to day 14. During the recovery from AKI, MMP-2(+/+) mice were also treated with MMP-2/MMP-9 inhibitor. RESULTS: In both MMP-2(+/+) and MMP-2(-/-) mice, AKI developed on day 1 after ischemia/reperfusion with widespread acute tubular injury, but subsequent epithelial cell proliferation was evident on days 3-7. During the repair process, active MMP-2 and MMP-9 increased in regenerating tubular epithelial cells in MMP-2(+/+) mice on days 7-14, and the tubular repair process was almost complete by day 14. On the other hand, in MMP-2(-/-) mice, less prominent proliferation of tubular epithelial cells was evident on days 3 and 7, and damaged tubules that were covered with elongated and immature regenerated epithelial cells were identified on days 7 and 14. Incomplete recovery of injured microvasculature was also noted with persistent macrophage infiltration. Similarly, treatment with MMP-2/MMP-9 inhibitor resulted in impaired recovery in MMP-2(+/+) mice. CONCLUSION: MMP-2 is involved in tubular repair after AKI. The use of the MMP-2/MMP-9 inhibitor was a disadvantage when it was administered during the repair stage of ischemic AKI. Treatment with MMP inhibitor for AKI needs to be modified to enhance recovery from AKI.