Alcohol Consumption and a Decline in Glomerular Filtration Rate: The Japan Specific Health Checkups Study.

Previous studies have reported conflicting results on the clinical impact of alcohol consumption on the glomerular filtration rate (GFR). This retrospective cohort study aimed to assess the dose-dependent association between alcohol consumption and the slope of the estimated GFR (eGFR) in 304,929 participants aged 40-74 years who underwent annual health checkups in Japan between April 2008 and March 2011. The association between the baseline alcohol consumption and eGFR slope during the median observational period of 1.9 years was assessed using linear mixed-effects models with the random intercept and random slope of time adjusting for clinically relevant factors. In men, rare drinkers and daily drinkers with alcohol consumptions of ≥60 g/day had a significantly larger decline in eGFR than occasional drinkers (difference in multivariable-adjusted eGFR slope with 95% confidence interval (mL/min/1.73 m2/year) of rare, occasional, and daily drinkers with ≤19, 20-39, 40-59, and ≥60 g/day: -0.33 [-0.57, -0.09], 0.00 [reference], -0.06 [-0.39, 0.26], -0.16 [-0.43, 0.12], -0.08 [-0.47, 0.30], and -0.79 [-1.40, -0.17], respectively). In women, only rare drinkers were associated with lower eGFR slopes than occasional drinkers. In conclusion, alcohol consumption was associated with the eGFR slope in an inverse U-shaped fashion in men but not in women.

Severe leukocytopenia due to copper deficiency induced by zinc supplementation in a patient on peritoneal dialysis: a case report.

Zinc deficiency is one cause of anemia. However, it has been reported that some patients who were treated with zinc supplementation to resolve this anemia subsequently experienced copper deficiency, which lead to continued anemia, as well as leukocytopenia and other symptoms. However, only two patients with copper deficiency induced by zinc supplementation undergoing peritoneal dialysis have been reported. Here, we report the case of a 59 year-old man with copper deficiency after zinc supplementation undergoing peritoneal dialysis (PD). He took meals only once a day and drank about 750 mL/day of wine every day. He had been receiving zinc supplementation for 4 months. He was diagnosed with severe leukocytopenia and worsening anemia at a planned outpatient visit; in addition, his copper levels had markedly decreased. Thus, zinc supplementation was discontinued, and the patient was instructed to take cocoa for copper supplementation. Because of severe leukocytopenia, he was admitted to our hospital, and granulocyte colony-stimulating factor was administered. Red blood cell transfusions were performed for anemia. After discontinuing zinc supplementation, his white blood cell count and hemoglobin levels improved.To avoid Cu deficiency, patients' dietary history should be checked in detail and Cu should be monitored carefully when Zn is supplemented in patients undergoing PD.

Tolvaptan Reduces Extracellular Fluid per Amount of Body Fluid Reduction Less Markedly than Conventional Diuretics.

Objective Tolvaptan, a vasopressin V2 receptor antagonist, is a water diuretic, removing electrolyte-free water from the kidneys and affecting the water balance between the intracellular and extracellular fluid. We previously reported that tolvaptan efficiently reduced the intracellular fluid volume, suggesting its utility for treating cellular edema. Furthermore, tolvaptan is known for its low incidence of worsening the renal function, with conventional diuretics use associated with worsening of the renal function Methods In this retrospective observational study, five chronic kidney disease (CKD) patients with fluid retention were assessed by the bioelectrical impedance (BIA) method twice (before and after tolvaptan therapy). Tolvaptan was used with conventional diuretics. The post/pre ratio of extracellular water (ECW)/total body water (TBW) in the tolvaptan group was compared with that in 18 CKD patients undergoing body fluid reduction with conventional diuretics alone (conventional diuretics groups), taking the reduced amount of body fluid into consideration. Results Removing body fluid, either by tolvaptan or by conventional diuretics alone, decreased the ECW/TBW ratio. Of note, the reduction in extracellular fluid was milder in the tolvaptan group than in the conventional diuretics group. Conclusion Tolvaptan reduces the extracellular fluid per amount of body fluid reduction less markedly than conventional diuretics.

A Formula for the Estimation of 24-Hour Urinary Creatinine Excretion: A Derivation and Validation Study.

OBJECTIVE: Twenty-four-hour urinary creatinine (Cr) excretion (24h-uCr) is the basis of Cr clearance and urinary protein-Cr ratio, and it is related to frailty, worsening kidney function, and mortality in patients with chronic kidney disease. Although subjects with lower estimated glomerular filtration rate (eGFR) tend to have lower 24h-uCr, previous formulae for the estimation of 24h-uCr did not include Cr as a predictor. METHODS: This retrospective study included patients admitted to the Department of Nephrology at our hospital (derivation cohort and validation cohort: patients admitted between April 2016 and March 2020). The prediction formula of 24h-uCr was calculated using a multivariate linear regression model with the bootstrap method. Age, height, weight, sex, Cr, and cystatin C were used as predictors. RESULTS: The derivation and validation cohorts included 187 and 63 patients, respectively. The characteristics of the derivation and validation cohorts were as follows: age 73 (61-79.5) years and 70 (58.5-79) years; males, 61.5% and 60.3%; eGFRCr 27.0 (13.7-48.6) mL/min/1.73 m2 and 26.3 (14.0-51.5) mL/min/1.73 m2; and 24-hour urinary protein excretion 0.79 (0.17-2.12) g/day and 1.08 (0.26-2.55) g/day, respectively. Seven prediction formulae were derived. In all models, the Pearson's correlation coefficient was relatively high and statistically significant. However, previous models tended to overestimate the 24h-uCr. Furthermore, the predicted 24h-uCr calculated by the models that do not include Cr as a predictor fluctuates depending on the eGFRCr. CONCLUSION: The best formula for predicting 24h-uCr (mg/day) in a wide range of eGFR populations is a Cr-containing formula: [-9.04 × age (years) + 8.03 × weight (kg) + 0.66 × height (cm) + 188.59 (if male) - 32.11 × Cr (mg/dL) + 779.14].

Intraoperative Near-Infrared Spectroscopy Monitoring of Renal Allograft Reperfusion in Kidney Transplant Recipients: A Feasibility and Proof-of-Concept Study.

Conventional renal function markers are unable to measure renal allograft perfusion intraoperatively, leading to delayed recognition of initial allograft function. A handheld near-infrared spectroscopy (NIRS) device that can provide real-time assessment of renal allograft perfusion by quantifying regional tissue oxygen saturation levels (rSO2) was approved by the FDA. This pilot study evaluated the feasibility of intraoperative NIRS monitoring of allograft reperfusion in renal transplant recipients (RTR). Intraoperative renal allograft rSO2 and perfusion rates were measured in living (LDRT, n = 3) and deceased donor RTR (DDRT, n = 4) during the first 50 min post-reperfusion and correlated with renal function markers 30 days post-transplantation. Intraoperative renal allograft rSO2 for the DDRT group remained significantly lower than the LDRT group throughout the 50 min. Reperfusion rates were significantly faster in the LDRT group during the first 5 min post-reperfusion but remained stable thereafter in both groups. Intraoperative rSO2 were similar among the upper pole, renal hilum, and lower pole, and strongly correlated with allograft function and hemodynamic parameters up to 14 days post-transplantation. NIRS successfully detected differences in intraoperative renal allograft rSO2, warranting future studies to evaluate it as an objective method to measure ischemic injury and perfusion for the optimization of preservation/reperfusion protocols and early prediction of allograft function.

Effect of cholecalciferol on serum hepcidin and parameters of anaemia and CKD-MBD among haemodialysis patients: a randomized clinical trial.

In this multicentre double-blind randomized clinical trial, we investigated the effects of oral cholecalciferol supplementation on serum hepcidin and parameters related to anaemia and CKD-MBD among haemodialysis patients. Participants were assigned in a 2:2:1:1 ratio to either (1) thrice-weekly 3,000-IU cholecalciferol, (2) once-monthly cholecalciferol (equivalent to 9,000 IU/week), (3) thrice-weekly placebo, or (4) once-monthly placebo. We also examined the effect modifications by selected single nucleotide polymorphisms in vitamin D-related genes. Out of 96 participants, 94 were available at Month 3, and 88 completed the 6-month study. After adjustment for baseline values, serum hepcidin levels were higher at Day 3 in the combined cholecalciferol (vs. placebo) group, but were lower at Month 6 with increased erythropoietin resistance. Cholecalciferol increased serum 1,25(OH)2D levels, resulting in a greater proportion of patients who reduced the dose of active vitamin D at Month 6 (31% vs. 10% in the placebo group). Cholecalciferol also suppressed intact PTH only among patients with severe vitamin D deficiency. In conclusion, cholecalciferol supplementation increases serum hepcidin-25 levels in the short term and may increase erythropoietin resistance in the long term among haemodialysis patients. Both thrice-weekly and once-monthly supplementation effectively increases serum 1,25(OH)2D levels, and hence, reduces active vitamin D drugs.Clinical Trial Registry: This study was registered at ClinicalTrials.gov and University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) as NCT02214563 (registration date: 12/08/2014) and UMIN000011786 (registration date: 15/08/2014), respectively (please refer to the links below). ClinicalTrials.gov: https://clinicaltrials.gov/ct2/show/record/NCT02214563 . UMIN-CTR: https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000017152&language=E .

High and low estimated glomerular filtration rates are associated with adverse outcomes in patients undergoing surgery for gastrointestinal malignancies.

BACKGROUND: Abnormally high estimated glomerular filtration rates (eGFRs) are associated with endothelial dysfunction and frailty. Previous studies have shown that low eGFR is associated with increased morbidity, but few reports address high eGFR. The purpose of this study is to evaluate the association of high eGFR with surgical outcomes in patients undergoing surgery for gastrointestinal malignancies. METHODS: We identified patients who underwent elective surgery for gastrointestinal malignancies from 2005 to 2015 in the American College of Surgeons National Surgical Quality Improvement Program database. We evaluated associations of eGFR with surgical outcomes by Cox or logistic models with restricted cubic spline functions, adjusting for case mix variables (i.e. age, gender, race and diabetes). RESULTS: The median eGFR is 83 (interquartile range 67-96) mL/min/1.73 m2. Thirty-day mortality was 1.9% (2555/136 896). There is a U-shaped relationship between eGFR and 30-day mortality. The adjusted hazard ratios (95% confidence intervals) for eGFRs of 30, 60, 105 and 120 mL/min/1.73 m2 (versus 90 mL/min/1.73 m2) are 1.73 (1.52-1.97), 1.00 (0.89-1.11), 1.42 (1.31-1.55) and 2.20 (1.79-2.70), respectively. Similar associations are shown for other surgical outcomes, including return to the operating room and postoperative pneumonia. Subgroup analyses show that eGFRs both higher and lower than the respective medians are consistently associated with a higher risk of adverse outcomes across age, gender and race. CONCLUSIONS: High and low eGFRs are associated with more adverse surgical outcomes in patients undergoing surgery for gastrointestinal malignancies. The eGFR associated with the lowest postoperative risk is approximately at the median eGFR of a given population.

Protein carbamylation exacerbates vascular calcification.

Protein carbamylation is a posttranslational modification that can occur non-enzymatically in the presence of high concentrations of urea. Although carbamylation is recognized as a prognostic biomarker, the contribution of protein carbamylation to organ dysfunction remains uncertain. Because vascular calcification is common under carbamylation-prone situations, we investigated the effects of carbamylation on this pathologic condition. Protein carbamylation exacerbated the calcification of human vascular smooth muscle cells (hVSMCs) by suppressing the expression of ectonucleotide pyrophosphate/phosphodiesterase 1 (ENPP1), a key enzyme in the generation of pyrophosphate, which is a potent inhibitor of ectopic calcification. Several mitochondrial proteins were carbamylated, although ENPP1 itself was not identified as a carbamylated protein. Rather, protein carbamylation reduced mitochondrial membrane potential and exaggerated mitochondria-derived oxidative stress, which down-regulated ENPP1. The effects of carbamylation on ectopic calcification were abolished in hVSMCs by ENPP1 knockdown, in mitochondrial-DNA-depleted hVSMCs, and in hVSMCs treated with a mitochondria-targeted superoxide scavenger. We also evaluated the carbamylation effects using ex vivo and in vivo models. The tunica media of a patient with end-stage renal disease was carbamylated. Thus, our findings have uncovered a previously unrecognized aspect of uremia-related vascular pathology.

Association of pre-operative estimated GFR on post-operative pulmonary complications in laparoscopic surgeries.

Despite a large body of evidence showing the pandemic of chronic kidney disease, the impact of pre-operative kidney function on the risk of post-operative pulmonary complications (PPCs) is not well known. We used multivariable logistic regression analyses with 3-level hierarchical adjustments to identify the association of pre-operative estimated glomerular filtration rate (eGFR) with PPCs in laparoscopic surgeries. Among 452,213 patients between 2005 and 2013 in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) Database, a total of 3,727 patients (0.9%) experienced PPCs. We found a gradient association between lower eGFR and higher likelihood of PPCs in the unadjusted model. In the case-mix adjusted model, a reverse-J-shaped association was observed; a small albeit significant association with the highest eGFR category emerged. Further adjustment slightly attenuated these associations, but the PPCs risk in the eGFR groups of <30, 30-60, and ≥120 mL/min/1.73 m2 remained significant: odds ratios (95% confidence intervals) of 1.82 (1.54-2.16), 1.38 (1.24-1.54), and 1.28 (1.07-1.53), respectively (reference: 90-120 mL/min/1.73 m2). Our findings propose a need for careful pre-operative evaluation of cardiovascular and pulmonary functions and post-operative fluid management among patients with not only lower but also very high eGFR.

Risk of Postoperative Venous Thromboembolism Among Pregnant Women.

Venous thromboembolism (VTE) is a critical complication after surgery. Although pregnancy is a known risk factor of VTE, available data on the risk of postoperative VTE are scarce. Using the American College of Surgeons National Surgical Quality Improvement Program database between 2006 and 2012, we matched 2,582 pregnant women to 103,640 nonpregnant women based on age, race, body mass index, and modified Rogers score. Pregnant women, compared with matched nonpregnant women, experienced higher incidence of VTE (0.5% vs 0.3%; odds ratio 1.93, 95% confidence interval 1.1 to 3.37, p = 0.02). Pregnant women also showed higher risk of pneumonia, ventilator dependence ≥48 hours, bleeding, and sepsis than did the counterparts. In conclusion, pregnancy was associated with higher risk of VTE after surgery as well as other postoperative complications. The absolute risk difference was small, and careful evaluation against the potential risk and benefit should be given when surgical treatment is considered among pregnant women.

[Uremic toxins and gut micro biome].

In the past, little attention had been paid to the intestine and its microbial flora as a potential source of systemic inflammation in chronic kidney disease(CKD). Systemic inflammation plays a central role in progression of CKD and its cardiovascular and various other complications. The gastrointestinal tract houses a large community of microbes that have a symbiotic relationship with the host. The normal microbial flora protects the host against pathogenic microorganisms. It also contributes to the energy metabolism, micronutrient homeostasis and nitrogen bal- ance. Recent studies have revealed significant changes in the composition and function of the microbial flora in CKD patients and animals. These changes are driven by altered intestinal bio- chemical environment caused by: I-heavy influx of urea and uric acid from body fluids into the gastrointestinal tract, II- restrictions of potassium-rich food including fruits and vegetables which as the main source of indigestible complex carbohydrates are the essential nutrients for the guts' symbiotic microbial com- munity, and III- various medications such as phosphate binders, antibiotics etc. Together the changes in intestinal milieu and the resultant microbial dysbiosis play a major role in systemic inflammation and uremic toxicity by several mechanisms : I-generation of several microbial derived uremic toxins such as indoxyl sulfate, p-cresol sulfate and trimethylamine-N-oxide etc. II-reduction of microbial derived micronutrients such a short chain fatty acids (SCFA) which are the main source of nutrients for colonocytes. This is caused by diminished substrates (indigestible complex carbohydrates) which leads to depletion of SCFA-making bacteria. In addition, III-Disruption of the intestinal epithelial barrier by ammonia and ammonium hydroxide generated from hydrolysis of urea by urease-possessing microbial species which are common complications of CKD, and bowel ischemia caused by excessive use of diuretics (in CKD patients) and aggressive ultrafiltration by hemodialysis (in ESRD patients) can impair gastrointestinal epithelial barrier. The resulting breakdown of the gut epithelial barrier (tight junction complex) leads to influx of endotoxin, microbial fragments, and other noxious luminal products in the sub-epithelial tissue and systemic circulation leading to local and systemic inflammation and oxidative stress which are the major cause of morbidity and mortality in CKD population. This review is intended to provide an overview of the effects of CKD on the gut microbiome and intestinal epithelial barrier structure and the potential interventions aimed at mitigating these abnormalities.

Intravenous Vitamin B6 Increases Resistance to Erythropoiesis-Stimulating Agents in Hemodialysis Patients: A Randomized Controlled Trial.

OBJECTIVE: Vitamin B6 deficiency is common in hemodialysis patients and may contribute to anemia and abnormal bone metabolism in this population. DESIGN: 6-month, open-label, randomized controlled parallel-group study in hemodialysis centers. SUBJECTS: Fifty-six maintenance hemodialysis patients with relatively high resistance to erythropoiesis-stimulating agents (ESA). INTERVENTION: Intravenous vitamin B6 (60 mg of intravenous pyridoxal 5'-phosphate after each thrice-weekly hemodialysis session). MAIN OUTCOME MEASURE: The primary and secondary outcomes were changes over time in ESA resistance index and bone turnover markers, respectively. RESULTS: The prevalence of vitamin B6 deficiency was 40% overall. Compared with the control group, the B6 group showed an upward change in ESA resistance index over time (Pinteraction = .038). At week 13 (a priori-defined time point), pyridoxal 5'-phosphate administration was associated with higher ESA resistance index by 0.97 (95% confidence interval, 0.02-1.92) ×10-2 µg ⋅darbepoetin-α/kg per g/dL⋅hemoglobin after baseline adjustment, which was not modified by baseline vitamin B6 status. There was a trend toward increase in serum erythropoietin concentrations in the B6 group after adjustment for baseline values, hemoglobin, and weekly ESA dose (Pinteraction = .06). The downward changes of bone-specific alkaline phosphatase and tartrate-resistant acid phosphatase 5b in the B6 group relative to the control group were pronounced in patients without vitamin B6 deficiency (Pinteraction < .001 and .017, respectively), despite nonsignificant between-group difference in 1-84 parathyroid hormone. CONCLUSIONS: Thrice-weekly intravenous vitamin B6 (60 mg pyridoxal 5'-phosphate hydrate) worsens the response to ESA and may blunt the response of bone to parathyroid hormone in hemodialysis patients.

Excess 25-hydroxyvitamin D3 exacerbates tubulointerstitial injury in mice by modulating macrophage phenotype.

Vitamin D hydroxylated at carbon 25 (25(OH)D) is generally recognized as a precursor of active vitamin D. Despite its low affinity for the vitamin D receptor (VDR), both deficient and excessive 25(OH)D levels are associated with poor clinical outcomes. Here we studied direct effects of 25(OH)D3 on the kidney using 25(OH)D-1α-hydroxylase (CYP27B1) knockout mice. The effects of 25(OH)D3 on unilateral ureteral obstruction were analyzed as proximal tubular cells and macrophages are two major cell types that take up 25(OH)D and contribute to the pathogenesis of kidney injury. Excess 25(OH)D3 in obstructed mice worsened oxidative stress and tubulointerstitial fibrosis, whereas moderate levels of 25(OH)D3 had no effects. The exacerbating effects of excess 25(OH)D3 were abolished in CYP27B1/VDR double-knockout mice and in macrophage-depleted CYP27B1 knockout mice. Excess 25(OH)D3 upregulated both M1 marker (TNF-α) and M2 marker (TGF-ß1) levels of kidney-infiltrating macrophages. In vitro analyses verified that excess 25(OH)D3 directly upregulated TNF-α and TGF-ß1 in cultured macrophages but not in tubular cells. TNF-α and 25(OH)D3 cooperatively induced oxidative stress by upregulating iNOS in tubular cells. Aggravated tubulointerstitial fibrosis in mice with excess 25(OH)D3 indicated that macrophage-derived TGF-ß1 also had a key role in the pathogenesis of surplus 25(OH)D3. Thus, excess 25(OH)D3 worsens tubulointerstitial injury by modulating macrophage phenotype.

Magnesium modifies the association between serum phosphate and the risk of progression to end-stage kidney disease in patients with non-diabetic chronic kidney disease.

It is known that magnesium antagonizes phosphate-induced apoptosis of vascular smooth muscle cells and prevents vascular calcification. Here we tested whether magnesium can also counteract other pathological conditions where phosphate toxicity is involved, such as progression of chronic kidney disease (CKD). We explored how the link between the risk of CKD progression and hyperphosphatemia is modified by magnesium status. A post hoc analysis was run in 311 non-diabetic CKD patients who were divided into four groups according to the median values of serum magnesium and phosphate. During a median follow-up of 44 months, 135 patients developed end-stage kidney disease (ESKD). After adjustment for relevant clinical factors, patients in the lower magnesium-higher phosphate group were at a 2.07-fold (95% CI: 1.23-3.48) risk for incident ESKD and had a significantly faster decline in estimated glomerular filtration rate compared with those in the higher magnesium-higher phosphate group. There were no significant differences in the risk of these renal outcomes among the higher magnesium-higher phosphate group and both lower phosphate groups. Incubation of tubular epithelial cells in high phosphate and low magnesium medium in vitro increased apoptosis and the expression levels of profibrotic and proinflammatory cytokine; these changes were significantly suppressed by increasing magnesium concentration. Thus, magnesium may act protectively against phosphate-induced kidney injury.

Dietary L-lysine prevents arterial calcification in adenine-induced uremic rats.

Vascular calcification (VC) is a life-threatening complication of CKD. Severe protein restriction causes a shortage of essential amino acids, and exacerbates VC in rats. Therefore, we investigated the effects of dietary l-lysine, the first-limiting amino acid of cereal grains, on VC. Male Sprague-Dawley rats at age 13 weeks were divided randomly into four groups: low-protein (LP) diet (group LP), LP diet+adenine (group Ade), LP diet+adenine+glycine (group Gly) as a control amino acid group, and LP diet+adenine+l-lysine·HCl (group Lys). At age 18 weeks, group LP had no VC, whereas groups Ade and Gly had comparable levels of severe VC. l-Lysine supplementation almost completely ameliorated VC. Physical parameters and serum creatinine, urea nitrogen, and phosphate did not differ among groups Ade, Gly, and Lys. Notably, serum calcium in group Lys was slightly but significantly higher than in groups Ade and Gly. Dietary l-lysine strongly suppressed plasma intact parathyroid hormone in adenine rats and supported a proper bone-vascular axis. The conserved orientation of the femoral apatite in group Lys also evidenced the bone-protective effects of l-lysine. Dietary l-lysine elevated plasma alanine, proline, arginine, and homoarginine but not lysine. Analyses in vitro demonstrated that alanine and proline inhibit apoptosis of cultured vascular smooth muscle cells, and that arginine and homoarginine attenuate mineral precipitations in a supersaturated calcium/phosphate solution. In conclusion, dietary supplementation of l-lysine ameliorated VC by modifying key pathways that exacerbate VC.

Multidetector-row computed tomography is useful to evaluate the therapeutic effects of bisphosphonates in glucocorticoid-induced osteoporosis.

Osteoporosis is one of the major complications of glucocorticoid therapy. Osteoporosis is usually defined by the levels of bone mineral density (BMD) assessed by dual energy X-ray absorptiometry (DEXA); however, glucocorticoids often induce fractures in patients with normal BMD. Thus, novel diagnostic approaches are required. In this study, we examined whether multidetector-row computed tomography (MDCT) is useful to assess the bone status in glucocorticoid-induced osteoporosis (GIO). Because bisphosphonates have been proven to prevent bone fracture in GIO, we tried to detect the therapeutic effects of bisphosphonates in GIO by MDCT. Fifteen Japanese patients with immunoglobulin A nephropathy who had normal renal function were enrolled in this open-label randomized trial. Patients were randomly divided into three groups-calcitriol (VD), menatetrenone (VK), or bisphosphonate (Bis). Bone conditions were analyzed twice by three different methods-bone turnover markers, DEXA, and MDCT-at the start and 6 months after the start of therapy. Both bone markers and DEXA could not detect significant differences among the therapeutic groups; however, MDCT-based analyses detected the preventive effects of bisphosphonates in GIO. Compared to VD, Bis improved structural indices, such as bone volume fraction, trabecular separation, marrow star volume, and structure model index whereas the difference between VD and VK was not significant. Finite element analysis revealed that simulated fracture load in the Bis group was significantly improved. These findings suggested that MDCT-based assessment is superior to bone markers and/or DEXA in assessing the therapeutic effect of bisphosphonates on GIO.

Retention of fetuin-A in renal tubular lumen protects the kidney from nephrocalcinosis in rats.

The serum glycoprotein fetuin-A is an important inhibitor of extraosseous calcification. The importance of fetuin-A has been confirmed in fetuin-A null mice, which develop widespread extraosseous calcification including the kidney. However, the mechanism how fetuin-A protects kidneys from nephrocalcinosis remains uncertain. Here, we demonstrate that intratubular fetuin-A plays a role in the prevention of nephrocalcinosis in the proximal tubules. Although normal rat kidney did not express mRNA for fetuin-A, we found punctate immunohistochemical staining of fetuin-A mainly in the S1 segment of the proximal tubules. The staining pattern suggested that fetuin-A passed through the slit diaphragm, traveled in the proximal tubular lumen, and was introduced into proximal tubular cells by megalin-mediated endocytosis. To test this hypothesis, we inhibited the function of megalin by intravenous injection of histidine-tagged soluble receptor-associated protein (His-sRAP), a megalin inhibitor. His-sRAP injection diminished fetuin-A staining in the proximal tubules and led to urinary excretion of fetuin-A. We further analyzed the role of fetuin-A in nephrocalcinosis. Continuous injection of parathyroid hormone (PTH) 1-34 induced nephrocalcinosis mainly in the proximal tubules in rats. His-sRAP retained fetuin-A in renal tubular lumen and thereby protected the kidneys of PTH-treated rats from calcification. Our findings suggest that tubular luminal fetuin-A works as a natural inhibitor against calcification in the proximal tubules under PTH-loaded condition.

Fibroblast growth factor 23 and 25-hydroxyvitamin D levels are associated with estimated glomerular filtration rate decline.

The combination of serum 25-hydroxyvitamin D (25D) and fibroblast growth factor 23 (FGF23) levels predict hard renal outcomes in patients with chronic kidney disease (CKD), independent of classical markers of mineral and bone disorders, including serum phosphorus, parathyroid hormone, 1,25-dihydroxyvitamin D levels, and active vitamin D therapy. In a prospective cohort study of 738 Japanese pre-dialysis outpatients with CKD, we examined potentially non-linear associations between 25D and FGF23 levels and estimated glomerular filtration rate (eGFR) changes in 727 patients with at least a 6-month observation period and no history of admission by acute kidney injury. We used multiple regression analyses with restricted cubic spline functions using annualized eGFR decline as a dependent variable. A significantly non-linear positive relationship between 25D and eGFR changes was observed. The annualized eGFR decline was greater in patients with 25D concentrations <25 and 23 ng/ml in univariate and multivariate analyses, respectively. Above this threshold, the eGFR decline plateaued. FGF23 showed a linear negative association with eGFR changes. After dividing the patients into four groups according to median 25D and FGF23 levels, the annualized eGFR changes in the Low FGF23-Low 25D, High FGF23-High 25D, and High FGF23-Low 25D groups were 0.49 (95% confidence intervals: -2.83 to 3.81), -1.24 (-5.00 to 2.52), -4.77 (-8.85 to -0.69), respectively, relative to the Low FGF23-High 25D group (P for trend, 0.02). Thus, combined use of FGF23 and 25D is useful to predict eGFR change in patients with CKD as well as hard renal outcomes.

Maxacalcitol ameliorates tubulointerstitial fibrosis in obstructed kidneys by recruiting PPM1A/VDR complex to pSmad3.

Tubulointerstitial fibrosis (TIF) is one of the major problems in nephrology because satisfactory therapeutic strategies have not been established. Here, we demonstrate that maxacalcitol (22-oxacalcitriol (OCT)), an analog of active vitamin D, protects the kidney from TIF by suppressing the autoinduction of transforming growth factor-ß1 (TGF-ß1). OCT suppressed the tubular injury index, interstitial volume index, collagen I positive area, and mRNA levels of extracellular matrix genes in unilateral ureteral-obstructed kidneys in rats. Although the renoprotective mechanism of active vitamin D in previous studies has been mainly attributed to the suppression of renin, OCT did not affect renal levels of renin or angiotensin II. We found that TGF-ß1 itself induces its expression in a phospho-Smad3 (pSmad3)-dependent manner, and that OCT ameliorated TIF by abrogating this 'autoinduction'. Under the stimulation of TGF-ß1, pSmad3 bound to the proximal promoter region of the TGF-ß1 gene. Both OCT and SIS3, a Smad3 inhibitor, abrogated the binding of pSmad3 to the promoter and consequently attenuated the autoinduction. TGF-ß1 increased both the nuclear levels of protein phosphatase Mg(2+)/Mn(2+)-dependent 1A (PPM1A), a pSmad3 phosphatase, and the interaction levels between the vitamin D receptor (VDR) and PPM1A. In the absence of OCT, however, the interaction between pSmad3 and PPM1A was weak; therefore, it was insufficient to dephosphorylate pSmad3. The PPM1A/VDR complex was recruited to pSmad3 in the presence of both TGF-ß1 and OCT. This recruitment promoted the dephosphorylation of pSmad3 and attenuated the pSmad3-dependent production of TGF-ß1. Our findings provide a novel approach to inhibit the TGF-ß pathway in fibrotic diseases.

Intact fibroblast growth factor 23 levels predict incident cardiovascular event before but not after the start of dialysis.

PURPOSE: Low 25-hydroxyvitamin D (25D), increased levels of fibroblast growth factor 23 (FGF23), parathyroid hormone (PTH), and alkaline phosphatase (ALP) were reported to be risk factors for mortality in chronic kidney disease (CKD). However, the independent associations of these factors with cardiovascular disease (CVD), the leading cause of death among CKD patients, remain unclear. Our purpose was to identify which of these factors predict incident CVD in CKD. METHODS: In this prospective cohort study, we enrolled 738 predialysis outpatients in the two nephrology departments. We employed Cox proportional hazards analyses to elucidate predictors of the endpoint, defined as fatal or non-fatal cardiovascular event requiring hospitalization. Multiple imputation was performed for missing values. RESULTS: Mean estimated glomerular filtration rate (eGFR) was 35 mL/min/1.73 m(2). During a median duration of 4.4 years, 86 patients developed the endpoint, of whom 62 patients achieved it before the initiation of dialysis. Multivariable analyses revealed that high serum intact FGF23 levels predicted the outcome preceding dialysis initiation (hazard ratio (HR) per lnFGF23 (SD), 1.64 (1.27-2.30)), while 25D, PTH, and bone-specific ALP did not. Adding FGF23 to the conventional model of age, sex, diabetes, prior CVD, pulse pressure, and eGFR, led to a net reclassification improvement of 6.87% (P=0.04). Not censoring the patients at the start of dialysis and continuing follow-up even after dialysis, FGF23 levels did not predict the outcome (HR, 1.16 (0.91-1.48)). Complete case analyses yielded similar results. CONCLUSIONS: Intact FGF23 levels in predialysis CKD predicted incident cardiovascular events requiring hospitalization before starting dialysis, but did not predict events during the entire follow-up period, including post dialysis initiation.