End-stage renal disease (ESRD) is a major public health problem, affecting 1 in 1,000 individuals and with an annual death rate of 20% despite dialysis treatment. IgA nephropathy (IgAN) is the most common form of glomerulonephritis, a principal cause of ESRD worldwide; it affects up to 1.3% of the population and its pathogenesis is unknown. Kidneys of people with IgAN show deposits of IgA-containing immune complexes with proliferation of the glomerular mesangium (Fig. 1). Typical clinical features include onset before age 40 with haematuria and proteinuria (blood and protein in the urine), and episodes of gross haematuria following mucosal infections are common; 30% of patients develop progressive renal failure. Although not generally considered a hereditary disease, striking ethnic variation in prevalence and familial clustering, along with subclinical renal abnormalities among relatives of IgAN cases, have suggested a heretofore undefined genetic component. By genome-wide analysis of linkage in 30 multiplex IgAN kindreds, we demonstrate linkage of IgAN to 6q22-23 under a dominant model of transmission with incomplete penetrance, with a lod score of 5.6 and 60% of kindreds linked. These findings for the first time indicate the existence of a locus with large effect on development of IgAN and identify the chromosomal location of this disease gene.

Persistent hyperparathyroidism (HPT) after kidney transplantation (KTx) is associated with hypercalcemia, hypophosphatemia and abnormally high levels of parathyroid hormone (PTH). In this randomized trial, cinacalcet was compared to placebo for the treatment of hypercalcemia in adult patients with persistent HPT after KTx. Subjects were randomized 1:1 to cinacalcet or placebo with randomization stratified by baseline corrected total serum calcium levels ( 11.2 mg/dL [2.80 mmol/L] or >11.2 mg/dL [2.80 mmol/L]). The primary end point was achievement of a mean corrected total serum calcium value <10.2 mg/dL (2.55 mmol/L) during the efficacy period. The two key secondary end points were percent change in bone mineral density (BMD) at the femoral neck and absolute change in phosphorus; 78.9% cinacalcetversus 3.5% placebo-treated subjects achieved the primary end point with a difference of 75.4% (95% confidence interval [CI]: 63.8, 87.1), p < 0.001. There was no statistical difference in the percent change in BMD at the femoral neck between cinacalcet and placebo groups, p ¼ 0.266. The difference in the change in phosphorus between the two arms was 0.45 mg/dL (95% CI: 0.26, 0.64), p < 0.001 (nominal). No new safety signals were detected. In conclusion, hypercalcemia and hypophosphatemia were effectively corrected after treatment with cinacalcet in patients with persistent HPT after KTx.

Background and objectives Cinacalcet and vitamin D are often combined to treat secondary hyperparathyroidism (SHPT) in patients on dialysis. Independent effects on fibroblast growth factor-23 (FGF-23) concentrations in patients on hemodialysis administered cinacalcet or vitamin D analogs as monotherapies during treatment of SHPT are evaluated.Design, setting, participants, & measurements A multicenter, randomized, open-label study to compare the efficacy of cinacalcet versus traditional vitamin D therapy for management of secondary hyperparathyroidism among subjects undergoing hemodialysis (PARADIGM) was a prospective, phase 4, multicenter, randomized, open-label study conducted globally. Participants (n=312) were randomized 1:1 to cinacalcet (n=155) or vitamin D analog (n=157) for 52 weeks. Levels of FGF-23 were measured at baseline and weeks 20 and 52. The absolute and percentage changes from baseline in plasma FGF-23, parathyroid hormone (PTH), calcium (Ca), phosphorus (P), and calcium-phosphorus product (Ca3P) were assessed. Correlations and logistic regression were used to explore relationships between changes in FGF-23 and changes in PTH, Ca, P, and Ca3P from baseline to week 52 by treatment arm.Results Median (quartiles 1, 3) decrease in FGF-23 concentrations was observed in the cinacalcet arm (240%; 263%, 16%) compared with median increase in the vitamin D analog arm (47%; 0%, 132%) at week 52 (P,0.001). Changes in FGF-23 in both arms were unrelated to changes in PTH (cinacalcet: r=0.17, P=0.11; vitamin D analog: r=20.04, P=0.70). Changes in FGF-23 in the vitamin D analog but not the cinacalcet arm were correlated with changes in Ca (cinacalcet: r=0.11, P=0.30; vitamin D analog: r=0.32, P,0.01) and P (cinacalcet: r=0.19, P=0.07; vitamin D analog: r=0.49, P,0.001). Changes in FGF-23 were correlated with changes in Ca3P in both arms (cinacalcet: r=0.26, P=0.01; vitamin D analog: r=0.57, P,0.001). Independent of treatment arm, participants with reductions in P or Ca3P were significantly more likely to show reductions in FGF-23.Conclusions During treatment of SHPT, cinacalcet use was associated with a decrease in FGF-23 concentrations, whereas vitamin D analogs were associated with an increase. The divergent effects of these treatments on FGF-23 seem to be independent of modification of PTH. It is possible that effects of cinacalcet and vitamin D analogs on FGF-23 may be mediated indirectly by other effects on bone and mineral metabolism.

Background and objectives Direct comparison of cinacalcet and vitamin D analogs as monotherapies to lower parathyroid hormone (PTH) levels has not been undertaken.Design, setting, participants, & measurements This was a prospective, multicenter, phase 4, randomized, openlabel study that enrolled participants from 2010 to 2012. Adult participants (n=312) on hemodialysis with PTH .450 pg/ml were randomized 1:1 to 12 months of treatment with either cinacalcet (n=155) or vitamin D analogs (n=157) to evaluate the mean percentage change in plasma PTH level (primary end point) and the proportion of participants achieving plasma PTH ,300 pg/ml or a $30% decrease in PTH (secondary end points). A preplanned analysis to determine whether there were important region-by-treatment interactions was also undertaken.Results Baseline mean PTH was 846 pg/ml (n=155) for cinacalcet and 816 pg/ml (n=157) for vitamin D analog therapy. The mean (95% confidence interval) percentage change from baseline in PTH was 212.1% (220.0% to 24.1%) in the cinacalcet arm and 27.0% (214.9% to 0.8%) in the vitamin D analog arm, a difference of 25.0% (215.4% to 5.4%) (P=0.35). Similarly, there was no difference in achievement of secondary efficacy end points between arms (19.4% and 15.3% of participants with PTH#300 pg/ml and 42.6% and 33.8% of participants had a PTH reduction .30% in the cinacalcet and vitamin D analog arms, respectively). A prespecified analysis revealed a large treatment-by-region interaction, with nominally greater response to cinacalcet compared with vitamin D analogs in non-United States participants (US versus non-US participants, P,0.001). Hypocalcemia was more common in the cinacalcet arm, whereas hypercalcemia and hyperphosphatemia occurred more often in the vitamin D analog arm.Conclusions Participants had similar modest reductions in PTH with either cinacalcet or vitamin D analog monotherapy over 52 weeks of treatment, but effects varied by region. Treatments differed with regard to effect on calcium and phosphorus levels.

Patients managed by a fracture prevention clinic service following a MTF have fewer new fractures and are more likely to be on treatment for bone fragility.

These results indicate that cinacalcet with low-dose active vitamin D, if prescribed, provides a more effective treatment approach than usual care without cinacalcet for SHPT in incident haemodialysis patients, even in relatively treatment-naive patients.

Renal energy metabolism was investigated before, during, and after ischemic insults of varying durations with in vivo 31P NMR spectroscopy. The postischemic recovery of renal ATP was found to be a biphasic process regardless of the length of the ischemia. This two-stage recovery consisted of a quick initial component immediately upon reflow followed by a slower, more gradual return toward preischemlc levels. To characterize the source of each phase of the recovery, kidneys were extracted with perchloric acid at the end of the different periods of ischemia (before reflow). Concentrations of adenine nucleotides and breakdown products adenosine, inosine, and hypoxanthine were determined by 1H NMR spectroscopy. Excellent correlation was found between the residual nucleotide pool and the magnitude of the initial phase of ATP recovery. Additionally, the renal ATP content after 120 min of reflow was shown to have a strong correlation with subsequent functional recovery. These experiments show that in vivo 31P NMR can provide new and dynamic information concerning the biochemical recovery from ischemia. Furthermore, this data has the potential to predict the eventual functional recovery of the organ.It is well-known that during renal ischemia, ATP levels fall to less than 25% of preischemic values and remain low for the duration of the insult (1-9). After an ischemic episode, the recovery of ATP is incomplete (2-5, 10). Previous studies from our laboratory (8, 9) using in vivo 31P NMR indicated that, after 45 min of bilateral renal artery occlusion, the recovery of cellular ATP is a biphasic process. There is a rapid initial recovery of ATP immediately upon reflow and a slower, more gradual recovery that continues as ATP returns toward its preischemic levels. In addition, these previous studies showed that postischemic augmentation of cellular ATP by the infusion of adenine nucleotides was associated with significant improvement in renal function 24 hr after the initial injury (8,9,11,12).The present study evaluates both of these previous observations by varying the duration of the insult in order to modulate the biochemical and functional severity of the ischemic injury. In this manner, we determined the components of the biphasic recovery of cellular ATP and also the relationship of functional recovery to the renal ATP concentration after 2 hr of reflow. The magnitude of the initial recovery of ATP was found to be a good index of the residual adenine nucleotide pool in the kidney at the end of the ischemic interval. In addition, there is a direct linear correlation between the tissue concentration of ATP following 120 min of recovery and renal function 24 hr later. Moreover, the pattern of recovery of renal ATP during this time period provides an assessment of the net rate of ATP resynthesis.Thus, delineation of the recovery of cellular ATP by in vivo 31P NMR provides new and dynamic information concerning the biochemical and functional recovery from an ischemic renal injury. MATERIALS AND METHODSIn Vivo NMR E...

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