Showing papers in "Journal of The American Society of Nephrology in 2005"

Acute Kidney Injury, Mortality, Length of Stay, and Costs in Hospitalized Patients

Abstract: The marginal effects of acute kidney injury on in-hospital mortality, length of stay (LOS), and costs have not been well described. A consecutive sample of 19,982 adults who were admitted to an urban academic medical center, including 9210 who had two or more serum creatinine (SCr) determinations, was evaluated. The presence and degree of acute kidney injury were assessed using absolute and relative increases from baseline to peak SCr concentration during hospitalization. Large increases in SCr concentration were relatively rare (e.g., >or=2.0 mg/dl in 105 [1%] patients), whereas more modest increases in SCr were common (e.g., >or=0.5 mg/dl in 1237 [13%] patients). Modest changes in SCr were significantly associated with mortality, LOS, and costs, even after adjustment for age, gender, admission International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis, severity of illness (diagnosis-related group weight), and chronic kidney disease. For example, an increase in SCr >or=0.5 mg/dl was associated with a 6.5-fold (95% confidence interval 5.0 to 8.5) increase in the odds of death, a 3.5-d increase in LOS, and nearly 7500 dollars in excess hospital costs. Acute kidney injury is associated with significantly increased mortality, LOS, and costs across a broad spectrum of conditions. Moreover, outcomes are related directly to the severity of acute kidney injury, whether characterized by nominal or percentage changes in serum creatinine.

Serum Phosphate Levels and Mortality Risk among People with Chronic Kidney Disease

Abstract: Elevated serum phosphate levels have been linked with vascular calcification and mortality among dialysis patients. The relationship between phosphate and mortality has not been explored among patients with chronic kidney disease (CKD). A retrospective cohort study was conducted from eight Veterans Affairs’ Medical Centers located in the Pacific Northwest. CKD was defined by two continuously abnormal outpatient serum creatinine measurements at least 6 mo apart between 1999 and 2002. Patients who received chronic dialysis, those with a present or previous renal transplant, and those without a recent phosphate measurement were excluded. The primary end point was all-cause mortality. Secondary end points were acute myocardial infarction and the combined end point of myocardial infarction plus death. A total of 95,619 veterans with at least one primary care or internal medicine clinic contact from a Northwest VA facility and two or more outpatient measurements of serum creatinine, at least 6 mo apart, between January 1, 1999, and December 31, 2002, were identified. From this eligible population, 7021 patients met our definition of CKD. After exclusions, 6730 CKD patients were available for analysis, and 3490 had a serum phosphate measurement during the previous 18 mo. After adjustment, serum phosphate levels >3.5 mg/dl were associated with a significantly increased risk for death. Mortality risk increased linearly with each subsequent 0.5-mg/dl increase in serum phosphate levels. Elevated serum phosphate levels were independently associated with increased mortality risk among this population of patients with CKD.

Chronic Hypoxia and Tubulointerstitial Injury: A Final Common Pathway to End-Stage Renal Failure

Abstract: Recent studies emphasize the role of chronic hypoxia in the tubulointerstitium as a final common pathway to end-stage renal failure. When advanced, tubulointerstitial damage is associated with the loss of peritubular capillaries. Associated interstitial fibrosis impairs oxygen diffusion and supply to tubular and interstitial cells. Hypoxia of tubular cells leads to apoptosis or epithelial-mesenchymal transdifferentiation. This in turn exacerbates fibrosis of the kidney and subsequent chronic hypoxia, setting in train a vicious cycle whose end point is ESRD. A number of mechanisms that induce tubulointerstitial hypoxia at an early stage have been identified. Glomerular injury and vasoconstriction of efferent arterioles as a result of imbalances in vasoactive substances decrease postglomerular peritubular capillary blood flow. Angiotensin II not only constricts efferent arterioles but, via its induction of oxidative stress, also hampers the efficient utilization of oxygen in tubular cells. Relative hypoxia in the kidney also results from increased metabolic demand in tubular cells. Furthermore, renal anemia hinders oxygen delivery. These factors can affect the kidney before the appearance of significant pathologic changes in the vasculature and predispose the kidney to tubulointerstitial injury. Therapeutic approaches that target the chronic hypoxia should prove effective against a broad range of renal diseases. Current modalities include the improvement of anemia with erythropoietin, the preservation of peritubular capillary blood flow by blockade of the renin-angiotensin system, and the use of antioxidants. Recent studies have elucidated the mechanism of hypoxia-induced transcription, namely that prolyl hydroxylase regulates hypoxia-inducible factor. This has given hope for the development of novel therapeutic approaches against this final common pathway.

Chronic Kidney Disease and the Risk for Cardiovascular Disease, Renal Replacement, and Death in the United States Medicare Population, 1998 to 1999

Abstract: Knowledge of the excess risk posed by specific cardiovascular syndromes could help in the development of strategies to reduce premature mortality among patients with chronic kidney disease (CKD). The rates of atherosclerotic vascular disease, congestive heart failure, renal replacement therapy, and death were compared in a 5% sample of the United States Medicare population in 1998 and 1999 (n = 1,091,201). Patients were divided into the following groups: 1, no diabetes, no CKD (79.7%); 2, diabetes, no CKD (16.5%); 3, CKD, no diabetes (2.2%); and 4, both CKD and diabetes (1.6%). During the 2 yr of follow-up, the rates (per 100 patient-years) in the four groups were as follows: atherosclerotic vascular disease, 14.1, 25.3, 35.7, and 49.1; congestive heart failure, 8.6, 18.5, 30.7, and 52.3; renal replacement therapy, 0.04, 0.2, 1.6, and 3.4; and death, 5.5, 8.1, 17.7, and 19.9, respectively (P < 0.0001). With use of Cox regression, the corresponding adjusted hazards ratios were as follows: atherosclerotic vascular disease, 1, 1.30, 1.16, and 1.41 (P < 0.0001); congestive heart failure, 1, 1.44, 1.28, and 1.79 (P < 0.0001); renal replacement therapy, 1, 2.52, 23.1, and 38.9 (P < 0.0001); and death, 1, 1.21, 1.38, and 1.56 (P < 0.0001). On a relative basis, patients with CKD were at a much greater risk for the least frequent study outcome, renal replacement therapy. On an absolute basis, however, the high death rates of patients with CKD may reflect accelerated rates of atherosclerotic vascular disease and congestive heart failure.

Fibroblast Growth Factor-23 Mitigates Hyperphosphatemia but Accentuates Calcitriol Deficiency in Chronic Kidney Disease

Abstract: Hyperphosphatemia, calcitriol deficiency, and secondary hyperparathyroidism (SHPT) are common complications of chronic kidney disease (CKD). Fibroblast growth factor-23 (FGF-23) is a novel phosphaturic hormone that also inhibits renal 1-hydroxylase activity and thus may be involved in the pathogenesis of SHPT. Several hypotheses were tested: that FGF-23 increases as renal function declines; is linearly associated with serum phosphate levels; is associated with increased phosphaturia independent of parathyroid hormone (PTH); and is associated with decreased calcitriol levels independent of renal function, hyperphosphatemia, and vitamin D stores. FGF-23, PTH, 25(OH)D3, calcitriol, calcium, phosphate, and urinary fractional excretion of phosphate (FePO4) were measured in 80 CKD patients. Multiple linear regression was used to test the hypotheses. FGF-23 and PTH were inversely associated with estimated GFR (eGFR), whereas calcitriol levels were linearly associated with eGFR. Hyperphosphatemia and hypocalcemia were present in only 12 and 6% of patients, respectively, all of whose eGFR was <30. Increased FePO4 was associated with decreased eGFR, and both increased FGF-23 and PTH were independently associated with increased FePO4. Increased FGF-23 and decreased 25(OH)D3 were independent predictors of decreased calcitriol, but the effects on calcitriol levels of renal function itself and hyperphosphatemia were completely extinguished by adjusting for FGF-23. It is concluded that FGF-23 levels increase early in CKD before the development of serum mineral abnormalities and are independently associated with serum phosphate, FePO4, and calcitriol deficiency. Increased FGF-23 may contribute to maintaining normal serum phosphate levels in the face of advancing CKD but may worsen calcitriol deficiency and thus may be a central factor in the early pathogenesis of SHPT.

Predictive Performance of the Modification of Diet in Renal Disease and Cockcroft-Gault Equations for Estimating Renal Function

Abstract: Recent recommendations emphasize the need to assess kidney function using creatinine-based predictive equations to optimize the care of patients with chronic kidney disease. The most widely used equations are the Cockcroft-Gault (CG) and the simplified Modification of Diet in Renal Disease (MDRD) formulas. However, they still need to be validated in large samples of subjects, including large non-U.S. cohorts. Renal clearance of (51)Cr-EDTA was compared with GFR estimated using either the CG equation or the MDRD formula in a cohort of 2095 adult Europeans (863 female and 1232 male; median age, 53.2 yr; median measured GFR, 59.8 ml/min per 1.73 m(2)). When the entire study population was considered, the CG and MDRD equations showed very limited bias. They overestimated measured GFR by 1.94 ml/min per 1.73 m(2) and underestimated it by 0.99 ml/min per 1.73 m(2), respectively. However, analysis of subgroups defined by age, gender, body mass index, and GFR level showed that the biases of the two formulas could be much larger in selected populations. Furthermore, analysis of the SD of the mean difference between estimated and measured GFR showed that both formulas lacked precision; the CG formula was less precise than the MDRD one in most cases. In the whole study population, the SD was 15.1 and 13.5 ml/min per 1.73 m(2) for the CG and MDRD formulas, respectively. Finally, 29.2 and 32.4% of subjects were misclassified when the CG and MDRD formulas were used to categorize subjects according to the Kidney Disease Outcomes Quality Initiative chronic kidney disease classification, respectively.

Uric Acid–Induced C-Reactive Protein Expression: Implication on Cell Proliferation and Nitric Oxide Production of Human Vascular Cells

Abstract: Recent experimental and human studies have shown that hyperuricemia is associated with hypertension, systemic inflammation, and cardiovascular disease mediated by endothelial dysfunction and pathologic vascular remodeling Elevated levels of C-reactive protein (CRP) have emerged as one of the most powerful independent predictors of cardiovascular disease In addition to being a marker of inflammation, recent evidence suggests that CRP may participate directly in the development of atherosclerotic vascular disease For investigating whether uric acid (UA)-induced inflammatory reaction and vascular remodeling is related to CRP, the UA-induced expression of CRP in human vascular smooth muscle cells (HVSMC) and human umbilical vein endothelial cells (HUVEC) was examined, as well as the pathogenetic role of CRP in vascular remodeling It is interesting that HVSMC and HUVEC expressed CRP mRNA and protein constitutively, revealing that vascular cells are another source of CRP production UA (6 to 12 mg/dl) upregulated CRP mRNA expression in HVSMC and HUVEC with a concomitant increase in CRP release into cell culture media Inhibition of p38 or extracellular signal-regulated kinase 44/42 significantly suppressed UA-induced CRP expression, implicating these pathways in the response to UA UA stimulated HVSMC proliferation whereas UA inhibited serum-induced proliferation of HUVEC assessed by 3H-thymidine uptake and cell counting, which was attenuated by co-incubation with probenecid, the organic anion transport inhibitor, suggesting that entry of UA into cells is responsible for CRP expression UA also increased HVSMC migration and inhibited HUVEC migration In HUVEC, UA reduced nitric oxide (NO) release Treatment of vascular cells with anti-CRP antibody revealed a reversal of the effect of UA on cell proliferation and migration in HVSMC and NO release in HUVEC, which suggests that CRP expression may be responsible for UA-induced vascular remodeling This is the first study to show that soluble UA, at physiologic concentrations, has profound effects on human vascular cells The observation that UA alters the proliferation/migration and NO release of human vascular cells, mediated by the expression of CRP, calls for careful reconsideration of the role of UA in hypertension and vascular disease

Activated Injectable Vitamin D and Hemodialysis Survival: A Historical Cohort Study

Abstract: Patients with ESRD commonly experience secondary hyperparathyroidism, a condition primarily managed with activated injectable vitamin D. The biologic effects of vitamin D, however, are widespread, and it is possible that activated injectable vitamin D alters survival in ESRD. This hypothesis was tested in a historical cohort study of incident hemodialysis patients who lived throughout the United States between January 1996 and December 1999. The primary outcome was 2-yr survival among those who survived for at least 90 d after initiation of chronic hemodialysis. During this period, 51,037 chronic hemodialysis patients survived for at least 90 d from the initiation of hemodialysis, and in the ensuing 2 yr, 37,173 received activated injectable vitamin D and 13,864 did not. At 2 yr, mortality rates were 13.8/100 person-years in the group that received injectable vitamin D compared with 28.6/100 person-years in the group that did not (P < 0.001). Cox proportional hazards analyses adjusting for several potential confounders and examining injectable vitamin D therapy as a time-dependent exposure suggested that compared with patients who did not receive injectable vitamin D, the 2-yr survival advantage associated with the group that did receive injectable vitamin D was 20% (hazard ratio, 0.80; 95% confidence interval, 0.76 to 0.83). The incidence of cardiovascular-related mortality was 7.6/100 person-years in the injectable vitamin D group, compared with 14.6/100 person-years in the non-vitamin D group (P < 0.001). The benefit of injectable vitamin D was evident in 48 of 49 strata examined, including those with low serum levels of intact parathyroid hormone and elevated levels of serum calcium and phosphorus, situations in which injectable vitamin D is often withheld. Repeating the entire analysis using marginal structural models to adjust for time-dependent confounding by indication yielded a survival advantage of 26% (hazard ratio, 0.74; 95% confidence interval, 0.71 to 0.79) associated with the injectable vitamin D group. In this historical cohort study, chronic hemodialysis patients in the group that received injectable vitamin D had a significant survival advantage over patients who did not. Randomized clinical trials would permit definitive conclusions.

Projecting the Number of Patients with End-Stage Renal Disease in the United States to the Year 2015

Abstract: The size of the prevalent ESRD population in the United States increased dramatically during the 1990s, from 196,000 in 1991 to 382,000 in 2000. Incidence also increased considerably during the same period, from 53,000 to 93,000 per year. If previous trends in ESRD incidence and prevalence continue, then current levels of health care resources that are devoted to the care of these patients will eventually be unable to meet the demand. This study discusses a Markov model developed to predict ESRD incidence, prevalence, and mortality to the year 2015 and incorporating expected changes in age/race distributions, diabetes prevalence, ESRD incidence, and probability of death. The model predicted that by 2015 there will be 136,166 incident ESRD patients per year (lower/upper limits 110,989 to 164,550), 712,290 prevalent patients (595,046 to 842,761), and 107,760 ESRD deaths annually (96,068 to 118,220). Incidence and prevalence counts are expected to increase by 44 and 85%, respectively, from 2000 to 2015 and incidence and prevalence rates per million population by 32 and 70%, respectively. The financial and human resources that will be needed to care for these patients in 2015 will be considerably greater than in 2005.

Performance of the Modification of Diet in Renal Disease and Cockcroft-Gault Equations in the Estimation of GFR in Health and in Chronic Kidney Disease

Abstract: The performance of the Modification of Diet in Renal Disease (MDRD) and the Cockcroft-Gault (CG) equations as compared with measured 125 I-iothalamate GFR (iGFR) was analyzed in patients with chronic kidney disease (CKD) and in potential kidney donors. All outpatients ( n = 1285) who underwent an iGFR between 1996 and 2003 were considered for analysis. Of these, 828 patients had CKD and 457 were potential kidney donors. Special emphasis was put on the calibration of the serum creatinine measurements. In CKD patients with GFR 2 , the MDRD equation performed better than the CG formula with respect to bias (−0.5 versus 3.5 ml/min per 1.73 m 2 , respectively) and accuracy within 30% (71 versus 60%, respectively) and 50% (89 versus 77%, respectively). Similar results are reported for 249 CKD patients with diabetes. In the kidney donor group, the MDRD equation significantly underestimated the measured GFR when compared with the CG formula, with a bias of −9.0 versus 1.9 ml/min per 1.73 m 2 , respectively ( P

Metabolic Syndrome and the Risk for Chronic Kidney Disease among Nondiabetic Adults

Abstract: The metabolic syndrome is a risk factor for the development of diabetes and cardiovascular disease; however, no prospective studies have examined the metabolic syndrome as a risk factor for chronic kidney disease (CKD). A total of 10,096 nondiabetic participants who were in the Atherosclerosis Risk in Communities study and had normal baseline kidney function composed the study cohort. The metabolic syndrome was defined according to recent guidelines from the National Cholesterol Education Program. Incident CKD was defined as an estimated GFR (eGFR) or =60 ml/min per 1.73 m2 at baseline. After 9 yr of follow-up, 691 (7%) participants developed CKD. The multivariable adjusted odds ratio (OR) of developing CKD in participants with the metabolic syndrome was 1.43 (95% confidence interval [CI], 1.18 to 1.73). Compared with participants with no traits of the metabolic syndrome, those with one, two, three, four, or five traits of the metabolic syndrome had OR of CKD of 1.13 (95% CI, 0.89 to 1.45), 1.53 (95% CI, 1.18 to 1.98), 1.75 (95% CI, 1.32 to 2.33), 1.84 (95% CI, 1.27 to 2.67), and 2.45 (95% CI, 1.32 to 4.54), respectively. After adjusting for the subsequent development of diabetes and hypertension during the 9 yr of follow-up, the OR of incident CKD among participants with the metabolic syndrome was 1.24 (95% CI, 1.01 to 1.51). The metabolic syndrome is independently associated with an increased risk for incident CKD in nondiabetic adults.

Podocyte Depletion Causes Glomerulosclerosis: Diphtheria Toxin–Induced Podocyte Depletion in Rats Expressing Human Diphtheria Toxin Receptor Transgene

Abstract: Glomerular injury and proteinuria in diabetes (types 1 and 2) and IgA nephropathy is related to the degree of podocyte depletion in humans. For determining the causal relationship between podocyte depletion and glomerulosclerosis, a transgenic rat strain in which the human diphtheria toxin receptor is specifically expressed in podocytes was developed. The rodent homologue does not act as a diphtheria toxin (DT) receptor, thereby making rodents resistant to DT. Injection of DT into transgenic rats but not wild-type rats resulted in dose-dependent podocyte depletion from glomeruli. Three stages of glomerular injury caused by podocyte depletion were identified: Stage 1, 0 to 20% depletion showed mesangial expansion, transient proteinuria and normal renal function; stage 2, 21 to 40% depletion showed mesangial expansion, capsular adhesions (synechiae), focal segmental glomerulosclerosis, mild persistent proteinuria, and normal renal function; and stage 3, >40% podocyte depletion showed segmental to global glomerulosclerosis with sustained high-grade proteinuria and reduced renal function. These pathophysiologic consequences of podocyte depletion parallel similar degrees of podocyte depletion, glomerulosclerosis, and proteinuria seen in diabetic glomerulosclerosis. This model system provides strong support for the concept that podocyte depletion could be a major mechanism driving glomerulosclerosis and progressive loss of renal function in human glomerular diseases.

Hemolytic Uremic Syndrome

Abstract: Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy defined by thrombocytopenia, nonimmune microangiopathic hemolytic anemia, and acute renal failure. The most frequent form is associated with infections by Shiga-like toxin-producing bacteria (STEC-HUS). Rarer cases are triggered by neuraminidase-producing Streptococcus pneumoniae (pneumococcal-HUS). The designation of aHUS is used to refer to those cases in which an infection by Shiga-like toxin-producing bacteria or S. pneumoniae can be excluded. Studies performed in the last two decades have documented that hyperactivation of the complement system is the pathogenetic effector mechanism leading to the endothelial damage and the microvascular thrombosis in aHUS. Recent data suggested the involvement of the complement system in the pathogenesis of STEC-HUS and pneumococcal-HUS as well. Clinical signs and symptoms may overlap among the different forms of HUS; however, pneumococcal-HUS and aHUS have a worse prognosis compared with STEC-HUS. Early diagnosis and identification of underlying pathogenetic mechanism allows instating specific support measures and therapies. In clinical trials in patients with aHUS, complement inhibition by eculizumab administration leads to a rapid and sustained normalization of hematological parameters with improvement in long-term renal function. This review summarizes current concepts about the epidemiological findings, the pathological and clinical aspects of STEC-HUS, pneumococcal-HUS, and aHUS, and their diagnosis and management.

Urine IL-18 Is an Early Diagnostic Marker for Acute Kidney Injury and Predicts Mortality in the Intensive Care Unit

Abstract: Serum creatinine is not an ideal marker of renal function in patients with acute kidney injury (AKI). Previous studies demonstrated that urinary IL-18 is increased in human AKI. Thus, whether urine IL-18 is an early diagnostic marker of AKI was investigated. A nested case-control study was performed within the Acute Respiratory Distress Syndrome (ARDS) Network trial. AKI was defined as an increase in serum creatinine by at least 50% within the first 6 d of ARDS study enrollment. A total of 400 urine specimens that were collected on study days 0, 1, and 3 of the ARDS trial were available from 52 case patients and 86 control patients. The data were analyzed in a cross-sectional manner and according to the time before development of AKI. The median urine IL-18 levels were significantly different at 24 and 48 h before AKI in case patients as compared with control patients. On multivariable analysis, urine IL-18 values predicted development of AKI 24 and 48 h later after adjustment for demographics, sepsis, Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) III score, serum creatinine, and urine output. Urine IL-18 levels of >100 pg/ml are associated with increased odds of AKI of 6.5 (95% confidence interval 2.1 to 20.4) in the next 24 h. On diagnostic performance testing, urine IL-18 demonstrates an area under the receiver operating characteristic curve of 73% to predict AKI in the next 24 h. The urine IL-18 values were also significantly different between survivors and nonsurvivors (P < 0.05), and on multivariable analysis, the urine IL-18 value on day 0 is an independent predictor of mortality. Urinary IL-18 levels can be used for the early diagnosis of AKI. Urine IL-18 levels also predict the mortality of patients who have ARDS and are in the intensive care unit.

Pathogenetic Mechanisms of Diabetic Nephropathy

Abstract: Diabetes is the leading cause of ESRD because diabetic nephropathy develops in 30 to 40% of patients. Diabetic nephropathy does not develop in the absence of hyperglycemia, even in the presence of a genetic predisposition. Multigenetic predisposition contributes in the development of diabetic nephropathy, thus supporting that many factors are involved in the pathogenesis of the disease. Hyperglycemia induces renal damage directly or through hemodynamic modifications. It induces activation of protein kinase C, increased production of advanced glycosylation end products, and diacylglycerol synthesis. In addition, it is responsible for hemodynamic alterations such as glomerular hyperfiltration, shear stress, and microalbuminuria. These alterations contribute to an abnormal stimulation of resident renal cells that produce more TGF-beta1. This growth factor upregulates GLUT-1, which induces an increased intracellular glucose transport and D-glucose uptake. TGF-beta1 causes augmented extracellular matrix protein deposition (collagen types I, IV, V, and VI; fibronectin, and laminin) at the glomerular level, thus inducing mesangial expansion and glomerular basement membrane thickening. However, low enzymatic degradation of extracellular matrix contributes to an excessive accumulation. Because hyperglycemia is the principal factor responsible for structural alterations at the renal level, glycemic control remains the main target of the therapy, whereas pancreas transplantation is the best approach for reducing the renal lesions.

Circulating Endothelial Microparticles Are Associated with Vascular Dysfunction in Patients with End-Stage Renal Failure

Abstract: Endothelial dysfunction and arterial stiffness are major determinants of cardiovascular risk in patients with end-stage renal failure (ESRF). Microparticles are membrane fragments shed from damaged or activated cells. Because microparticles can affect endothelial cells, this study investigated the relationship between circulating microparticles and arterial dysfunction in patients with ESRF and identified the cellular origin of microparticles associated with these alterations. Flow cytometry analysis of platelet-free plasma from 44 patients with ESRF indicated that circulating levels of Annexin V microparticles were increased compared with 32 healthy subjects, as were levels of microparticles derived from endothelial cells (three-fold), platelets (16.5-fold), and erythrocytes (1.6-fold). However, when arterial function was evaluated noninvasively in patients with ESRF, only endothelial microparticle levels correlated highly with loss of flow-mediated dilation (r 0.543; P 0.004), increased aortic pulse wave velocity (r 0.642, P < 0.0001), and increased common carotid artery augmentation index (r 0.463, P 0.0017), whereas platelet-derived, erythrocyte-derived, and Annexin V microparticle levels did not. In vitro, microparticles from patients with ESRF impaired endothelium-dependent relaxations and cyclic guanosine monophosphate generation, whereas microparticles from healthy subjects did not. Moreover, in vitro endothelial dysfunction correlated with endothelial-derived (r 0.891; P 0.003) but not platelet-derived microparticle concentrations. In fact, endothelial microparticles alone decreased endothelial nitric oxide release by 59 7% (P 0.025). This study suggests that circulating microparticles of endothelial origin are tightly associated with endothelial dysfunction and arterial dysfunction in ESRF.

Role of Reactive Oxygen Species in TGF-β1-Induced Mitogen-Activated Protein Kinase Activation and Epithelial-Mesenchymal Transition in Renal Tubular Epithelial Cells

Abstract: Epithelial-mesenchymal transition (EMT) plays an important role in renal tubulointerstitial fibrosis and TGF-beta1 is the key inducer of EMT. Phosphorylation of Smad proteins and/or mitogen-activated protein kinases (MAPK) is required for TGF-beta1-induced EMT. Because reactive oxygen species (ROS) are involved in TGF-beta1 signaling and are upstream signaling molecules to MAPK, this study examined the role of ROS in TGF-beta1-induced MAPK activation and EMT in rat proximal tubular epithelial cells. Growth-arrested and synchronized NRK-52E cells were stimulated with TGF-beta1 (0.2 to 20 ng/ml) or H(2)O(2) (1 to 500 microM) in the presence or absence of antioxidants (N-acetylcysteine or catalase), inhibitors of NADPH oxidase (diphenyleneiodonium and apocynin), mitochondrial electron transfer chain subunit I (rotenone), and MAPK (PD 98059, an MEK [MAP kinase/ERK kinase] inhibitor, or p38 MAPK inhibitor) for up to 96 h. TGF-beta1 increased dichlorofluorescein-sensitive cellular ROS, phosphorylated Smad 2, p38 MAPK, extracellular signal-regulated kinases (ERK)1/2, alpha-smooth muscle actin (alpha-SMA) expression, and fibronectin secretion and decreased E-cadherin expression. Antioxidants effectively inhibited TGF-beta1-induced cellular ROS, phosphorylation of Smad 2, p38 MAPK, and ERK, and EMT. H(2)O(2) reproduced all of the effects of TGF-beta1 with the exception of Smad 2 phosphorylation. Chemical inhibition of ERK but not p38 MAPK inhibited TGF-beta1-induced Smad 2 phosphorylation, and both MAPK inhibitors inhibited TGF-beta1- and H(2)O(2)-induced EMT. Diphenyleneiodonium, apocynin, and rotenone also significantly inhibited TGF-beta1-induced ROS. Thus, this data suggest that ROS play an important role in TGF-beta1-induced EMT primarily through activation of MAPK and subsequently through ERK-directed activation of Smad pathway in proximal tubular epithelial cells.

Anti–Factor H Autoantibodies Associated with Atypical Hemolytic Uremic Syndrome

Abstract: Several studies have demonstrated genetic predisposition in non-shigatoxin-associated hemolytic uremic syndrome (HUS), involving regulatory proteins of the complement alternative pathway: Factor H (FH) and membrane co-factor protein (CD46). Regarding the observations of thrombotic thrombocytopenic purpura patients, in whom a von Willebrand factor protease (ADAMST-13) deficiency may be inherited or acquired secondary to IgG antibodies, it was speculated that HUS might occur in a context of an autoimmune disease with the development of anti-FH antibodies leading to an acquired FH deficiency. The presence of FH autoantibodies was investigated by an ELISA method using coated purified human FH in a series of 48 children who presented with atypical HUS and were recruited from French university hospitals. Anti-FH IgG antibodies were detected in the plasma of three children who presented with recurrent HUS. The anti-FH specificity was conserved by the Fab'2 fraction. The plasma FH activity was found to be decreased, whereas plasma FH antigenic levels and FH gene analysis were normal, indicating that the presence of anti-FH antibodies led to an acquired functional FH deficiency. This report supports for the first time that HUS may occur in a context of an autoimmune disease with the development of anti-FH-specific antibody leading to an acquired FH deficiency. This new mechanism of functional FH deficiency may lead to the design of new approaches of diagnosis and treatment with a particular interest in plasma exchanges or immunosuppressive therapies.

Prevalence, Severity, and Importance of Physical and Emotional Symptoms in Chronic Hemodialysis Patients

Abstract: The prevalence, severity, and clinical significance of physical and emotional symptoms in patients who are on maintenance hemodialysis remain incompletely characterized. This study sought to assess symptoms and their relationship to quality of life and depression. The recently developed Dialysis Symptom Index was used to assess the presence and the severity of 30 symptoms. The Illness Effects Questionnaire and Beck Depression Inventory were used to evaluate quality of life and depression, respectively. Correlations among symptom burden, symptom severity, quality of life, and depression were assessed using Spearman correlation coefficient. A total of 162 patients from three dialysis units were enrolled. Mean age was 62 y, 48% were black, 62% were men, and 48% had diabetes. The median number of symptoms was 9.0 (interquartile range 6 to 13). Dry skin, fatigue, itching, and bone/joint pain each were reported by > or =50% of patients. Seven additional symptoms were reported by >33% of patients. Sixteen individual symptoms were described as being more than "somewhat bothersome." Overall symptom burden and severity each were correlated directly with impaired quality of life and depression. In multivariable analyses adjusting for demographic and clinical variables including depression, associations between symptoms and quality of life remained robust. Physical and emotional symptoms are prevalent, can be severe, and are correlated directly with impaired quality of life and depression in maintenance hemodialysis patients. Incorporating a standard assessment of symptoms into the care provided to maintenance hemodialysis patients may provide a means to improve quality of life in this patient population.

Traditional and Nontraditional Risk Factors Predict Coronary Heart Disease in Chronic Kidney Disease: Results from the Atherosclerosis Risk in Communities Study

Abstract: Some risk factors for coronary heart disease (CHD) incidence in the general population are not associated with CHD incidence among patients with ESRD but have not been well characterized in chronic kidney disease (CKD). The association of several risk factors with CHD incidence was studied among participants with CKD in the population-based Atherosclerosis Risk in Communities (ARIC) Study. CHD risk factors and estimated GFR using serum creatinine were measured among 807 ARIC participants with CKD (estimated GFR between 15 and 59 ml/min per 1.73 m 2 ). The incidence of CHD during 10.5 yr of follow-up was 6.3, 8.5, and 14.4 per 1000 person-years among ARIC participants with an estimated GFR of ≥90, 60 to 89, and 15 to 59 ml/min per 1.73 m 2 , respectively. After adjustment for age, race, gender, and ARIC field center, among those with CKD, the relative risk (95% confidence interval) of CHD was 1.65 (1.01 to 2.67) for current smoking, 2.02 (1.27 to 3.22) for hypertension, 3.06 (2.01 to 4.67) for diabetes, and 1.96 (1.14 to 3.36) for anemia. The comparably adjusted relative risks of CHD for each standard deviation higher total and HDL cholesterol were 1.50 (1.25 to 1.71) and 0.79 (0.62 to 1.01), respectively, and 1.38 (1.13 to 1.69), 1.24 (1.06 to 1.46), 0.65 (0.54 to 0.79), and 1.38 (1.19 to 1.59) for waist circumference, leukocyte count, serum albumin, and fibrinogen, respectively. CHD risk factors in the general population remain predictive among patients with CKD. Given the high risk for CHD among patients with CKD, control of these risk factors may have a substantial impact on their excess burden of CHD.

Mutations in Complement Factor I Predispose to Development of Atypical Hemolytic Uremic Syndrome

Abstract: Atypical hemolytic uremic syndrome (aHUS) is a disease of complement dysregulation. In approximately 50% of patients, mutations have been described in the genes encoding the complement regulators factor H, MCP, and factor I or the activator factor B. We report here mutations in the central component of the complement cascade, C3, in association with aHUS. We describe 9 novel C3 mutations in 14 aHUS patients with a persistently low serum C3 level. We have demonstrated that 5 of these mutations are gain-of-function and 2 are inactivating. This establishes C3 as a susceptibility factor for aHUS.

Long-Term Study of Mycophenolate Mofetil as Continuous Induction and Maintenance Treatment for Diffuse Proliferative Lupus Nephritis

Abstract: Mycophenolate mofetil (MMF) and the sequential use of cyclophosphamide followed by azathioprine (CTX-AZA) demonstrate similar short-term efficacy in the treatment of diffuse proliferative lupus nephritis (DPLN), but MMF is associated with less drug toxicity. Results from an extended long-term study, with median follow-up of 63 mo, that investigated the role of MMF as continuous induction-maintenance treatment for DPLN are presented. Thirty-three patients were randomized to receive MMF, and 31 were randomized to the CTX-AZA treatment arm, both in combination with prednisolone. More than 90% in each group responded favorably (complete or partial remission) to induction treatment. Serum creatinine in both groups remained stable and comparable over time. Creatinine clearance increased significantly in the MMF group, but the between-group difference was insignificant. Improvements in serology and proteinuria were comparable between the two groups. A total of 6.3% in the MMF group and 10.0% of CTX-AZA-treated patients showed doubling of baseline creatinine during follow-up (P = 0.667). Both the relapse-free survival and the hazard ratio for relapse were similar between MMF- and CTX-AZA-treated patients (11 and nine patients relapsed, respectively) and between those with MMF treatment for 12 or >/=24 mo. MMF treatment was associated with fewer infections and infections that required hospitalization (P = 0.013 and 0.014, respectively). Four patients in the CTX-AZA group but none in the MMF group reached the composite end point of end-stage renal failure or death (P = 0.062 by survival analysis). It is concluded that MMF and prednisolone constitute an effective continuous induction-maintenance treatment for DPLN in Chinese patients.

Type of Vascular Access and Survival among Incident Hemodialysis Patients: The Choices for Healthy Outcomes in Caring for ESRD (CHOICE) Study

Abstract: Arteriovenous fistulae (AVF) have advantages over arteriovenous grafts (AVG) and central venous catheters (CVC), but whether AVF are associated independently with better survival is unclear. Recent studies showing such a survival benefit did not include early access experience or account for changes in access type over time and did not include data on some important confounders. Reported here are survival rates stratified by the type of access in use up to 3 yr after initiation of hemodialysis among 616 incident patients who were enrolled in the Choices for Healthy Outcomes in Caring for ESRD (CHOICE) Study. A total of 1084 accesses (185 AVF, 296 AVG, 603 CVC) were used for a total of 1381 person-years. At initiation, 409 (66%) patients were using a CVC, 122 (20%) were using an AVG, and 85 (14%) were using an AVF. After 6 mo, 34% were using a CVC, 40% were using an AVG, and 26% were using an AVF. Annual mortality rates were 11.7% for AVF, 14.2% for AVG, and 16.1% for CVC. Adjusted relative hazards (RH) of death compared with AVF were 1.5 (95% confidence interval, 1.0 to 2.2) for CVC and 1.2 (0.8 to 1.8) for AVG. The increased hazards associated with CVC, as compared with AVF, were stronger in men (n = 334; RH = 2.0; P = 0.01) than women (n = 282; RH = 1.0 for CVC; P = 0.92). These results strongly support existing clinical practice guidelines and suggest that the use of venous catheters should be minimized to reduce the frequency of access complications and to improve patient survival, especially among male hemodialysis patients.

Chronic Renal Allograft Dysfunction

Abstract: The major causes of renal transplant loss are death from vascular, malignant or infectious disease, and loss of the allograft from chronic renal dysfunction associated with the development of graft fibrosis and glomerulosclerosis. Chronic allograft nephropathy (CAN) is the histologic description of the fibrosis, vascular and glomerular damage occurring in renal allografts. Clinical programs rely on monitoring change in serum creatinine for identification of patients at risk of CAN, but this change occurs late in the course of the disease, and underestimates the severity of pathologic change. CAN has several causes: ischemia-reperfusion injury, ineffectively or untreated clinical and subclinical rejection, and superimposed calcineurin inhibitor nephrotoxicity, exacerbating pre-existing donor disease. Once established, interstitial fibrosis and arteriolar hyalinosis lead to progressive glomerulosclerosis over the subsequent years. There have been a number of approaches to treatment aimed at reducing the impact of CAN, mostly centered around avoidance of calcineurin inhibitors through their elimination in all, or just selected, patients. These immunosuppression strategies combine corticosteroids with azathioprine or mycophenolate mofetil, and/or sirolimus and everolimus. Late identification of CAN in individual patients has meant that strategies for intervening to prevent chronic renal allograft dysfunction and subsequent graft loss tend to be "too little and far too late."

Chronic Kidney Disease and Cognitive Impairment in the Elderly: The Health, Aging, and Body Composition Study

Abstract: Previous studies suggest a link between chronic kidney disease (CKD) and cognitive impairment. Whether the longitudinal course of cognitive impairment differs among people with or without CKD is unknown. Data collected in 3034 elderly individuals who participated in the Health, Aging, and Body Composition study were analyzed. Cognitive function was assessed with the Modified Mini-Mental State Exam (3MS) at baseline and then 2 and 4 yr after baseline. Cognitive impairment was defined as a 3MS score 5 points after 2 or 4 yr of follow-up among participants with baseline 3MS scores > or =80. Participants with CKD, defined as an estimated GFR (eGFR) <60 ml/min per 1.73 m2, were further divided into two eGFR strata. Unadjusted mean baseline 3MS scores and mean declines in 3MS scores over 4 yr were significantly more pronounced for participants with lower baseline eGFR. More advanced stages of CKD were associated with an increased risk for cognitive impairment: Odds ratio (OR) 1.32 (95% confidence interval [CI] 1.03 to 1.69) and OR 2.43 (95% CI, 1.38 to 4.29) for eGFR 45 to 59 ml/min per 1.73 m2 and <45 ml/min per 1.73 m2, respectively, adjusted for case mix, baseline 3MS scores, and other potential confounders. CKD is associated with an increased risk for cognitive impairment in the elderly that cannot be fully explained by other well-established risk factors. Studies aimed at understanding the mechanism(s) responsible for cognitive impairment in CKD and efforts to interrupt this decline are warranted.

Cinacalcet HCl, an Oral Calcimimetic Agent for the Treatment of Secondary Hyperparathyroidism in Hemodialysis and Peritoneal Dialysis: A Randomized, Double-Blind, Multicenter Study

Abstract: Management of secondary hyperparathyroidism is challenging with traditional therapy. The calcimimetic cinacalcet HCl acts on the calcium-sensing receptor to increase its sensitivity to calcium, thereby reducing parathyroid hormone (PTH) secretion. This phase 3, multicenter, randomized, placebo-controlled, double-blind study evaluated the efficacy and safety of cinacalcet in hemodialysis (HD) and peritoneal dialysis (PD) patients with PTH > or =300 pg/ml despite traditional therapy. A total of 395 patients received once-daily oral cinacalcet (260 HD, 34 PD) or placebo (89 HD, 12 PD) titrated from 30 to 180 mg to achieve a target intact PTH (iPTH) level of or =30% reduction in iPTH from baseline (65 versus 13%), and proportion of patients with > or =20, > or =40, or > or =50% reduction from baseline. Cinacalcet had comparable efficacy in HD and PD patients; 50% of PD patients achieved a mean iPTH < or =300 pg/ml. Cinacalcet also significantly reduced serum calcium, phosphorus, and Ca x P levels compared with control treatment. The most common side effects, nausea and vomiting, were usually mild to moderate in severity and transient. Once-daily oral cinacalcet was effective in rapidly and safely reducing PTH, Ca x P, calcium, and phosphorus levels in patients who received HD or PD. Cinacalcet offers a new therapeutic option for controlling secondary hyperparathyroidism in patients with chronic kidney disease on dialysis.

Calcium, Phosphorus, Parathyroid Hormone, and Cardiovascular Disease in Hemodialysis Patients: The USRDS Waves 1, 3, and 4 Study

Abstract: Animal studies suggest that calcium-phosphorus homeostatic abnormalities cause cardiovascular disease in uremia; few observational studies in humans have explored this. Associations in the retrospective United States Renal Data System Waves 1, 3, and 4 Study of 14,829 patients who were on hemodialysis on December 31, 1993, were examined. Mean age and duration of renal replacement therapy were 60.0 and 3.2 yr, respectively; 40.7% had diabetes. Quintiles (Q 1 to Q 5 ) of (albumin-adjusted) calcium were ≤8.7, 8.8 to 9.2, 9.3 to 9.6, 9.7 to 10.2, and >10.2 mg/dl; phosphorus, ≤4.4, 4.5 to 5.3, 5.4 to 6.3, 6.4 to 7.5, and >7.5 mg/dl; calcium-phosphorus product, ≤40.9, 41.0 to 50.1, 50.2 to 59.2, 59.3 to 71.0, and >71.0 mg 2 /dl 2 ; and parathyroid hormone (PTH), ≤37, 38 to 99, 100 to 210, 211 to 480, and >480 pg/ml. Higher calcium levels were associated with fatal or nonfatal cardiovascular events (adjusted hazards ratio, 1.08 for Q 5 , versus Q 1 ) and all-cause mortality (Q 2 , 1.07; Q 4 , 1.11; Q 5 , 1.14). Phosphorus levels were associated with cardiovascular events (Q 2 , 1.06; Q 3 , 1.13; Q 4 , 1.14; Q 5 , 1.25) and mortality (Q 4 , 1.10; Q 5 , 1.19), calcium-phosphorus product was associated with cardiovascular events (Q 3 , 1.09; Q 4 , 1.14; Q 5 , 1.24) and mortality (Q 4 , 1.09; Q 5 , 1.19), and PTH levels were associated with cardiovascular events (Q 5 , 1.12) and mortality (Q 5 , 1.17). Despite limitations (including retrospective design; noncurrent study era; and lack of serial calcium, phosphorus, and PTH measurements), this study suggests that disorders of calcium homeostasis are associated with fatal and nonfatal cardiovascular events and all-cause mortality in hemodialysis patients.

Skin Autofluorescence, a Measure of Cumulative Metabolic Stress and Advanced Glycation End Products, Predicts Mortality in Hemodialysis Patients

Abstract: Tissue advanced glycation end products (AGE) are a measure of cumulative metabolic stress and trigger cytokines driven inflammatory reactions. AGE are thought to contribute to the chronic complications of diabetes and ESRD. Tissue autofluorescence is related to the accumulation of AGE. Therefore, skin autofluorescence (AF) may provide prognostic information on mortality in hemodialysis (HD) patients. Skin AF was measured noninvasively with an AF reader at baseline in 109 HD patients. Overall and cardiovascular mortality was monitored prospectively during a period of 3 yr. The AF reader was validated against AGE contents in skin biopsies from 29 dialysis patients. Forty-two of the 109 (38.5%) HD patients died. Cox regression analysis showed that AF was an independent predictor of overall and cardiovascular mortality (for overall mortality odds ratio [OR] 3.9), as were pre-existing cardiovascular disease (CVD; OR 3.1), C-reactive protein (OR 1.1), and serum albumin (OR 0.3). Multivariate analysis revealed that 65% of the variance in AF could be attributed to the independent effects of age, dialysis and renal failure duration, presence of diabetes, triglycerides levels, and C-reactive protein. AF was also independently linked to the presence of CVD at baseline (OR 8.8; P < 0.001). AF correlated with collagen-linked fluorescence (r = 0.71, P < 0.001), pentosidine (r = 0.75, P < 0.001), and carboxy(m)ethyllysine (both r = 0.45, P < 0.01). Skin AF is a strong and independent predictor of mortality in ESRD. This supports a role for AGE as a contributor to mortality and CVD and warrants interventions specifically aimed at AGE accumulation.

Asymmetrical Dimethylarginine Predicts Progression to Dialysis and Death in Patients with Chronic Kidney Disease: A Competing Risks Modeling Approach

Abstract: High plasma asymmetrical dimethylarginine (ADMA) signals endothelial dysfunction and atherosclerosis in the general population and predicts mortality in ESRD. The relationship among plasma levels of ADMA, renal function, and the risk for progression to ESRD (halving GFR or dialysis start) and death in an incident cohort of 131 patients with chronic kidney disease was investigated. Cox’s competing risk regression was used to model double-failure times (progression to ESRD and death) as a function of ADMA. Covariates that were considered for adjustment included clinical characteristics, baseline GFR (Modification of Diet in Renal Disease equation 7 formula), proteinuria, traditional cardiovascular risk factors, serum C-reactive protein, homocysteine, and concomitant therapies. Mean age at enrollment was 71 ± 11 yr, and 24% of patients had diabetes. Baseline GFR ranged from 8 to 77 ml/min per 1.73 m 2 (average 31 ± 15 ml/min per 1.73 m 2 ). ADMA was inversely related to GFR, ranking as the third predicting factor (partial r = −0.22, P = 0.01), after hemoglobin and urinary protein, in a general linear model that included multiple correlates of GFR. After a mean follow-up of 27 mo (range 3.4 to 36), 29 patients progressed to ESRD and 31 died. ADMA (hazard ratio per 0.1 μM/L 1.203; 95% confidence interval 1.071 to 1.350) predicted event occurrence independent of other potential confounders, including GFR, proteinuria, hemoglobin, and homocysteine. In patients with mild to advanced chronic kidney disease, plasma ADMA is inversely related to GFR and represents a strong and independent risk marker for progression to ESRD and mortality. These novel findings further expand the implications of previous observations in ESRD patients and generate hypotheses on the role of ADMA in progressive chronic nephropathies.

Membranoproliferative Glomerulonephritis Type II (Dense Deposit Disease): An Update

Abstract: Membranoproliferative glomerulonephritis type II (MPGN II) is a rare disease characterized by the deposition of abnormal electron-dense material within the glomerular basement membrane of the kidney and often within Bruch's membrane in the eye. The diagnosis is made in most patients between the ages of 5 and 15 yr, and within 10 yr, approximately half progress to end-stage renal disease, occasionally with the late comorbidity of visual impairment. The pathophysiologic basis of MPGN II is associated with the uncontrolled systemic activation of the alternative pathway (AP) of the complement cascade. In most patients, loss of complement regulation is caused by C3 nephritic factor, an autoantibody directed against the C3 convertase of the AP, but in some patients, mutations in the factor H gene have been identified. For the latter patients, plasma replacement therapy prevents renal failure, but for the majority of patients, there is no proven effective treatment. The disease recurs in virtually all renal allografts, and a high percentage of these ultimately fail. The development of molecular diagnostic tools and new therapies directed at controlling the AP of the complement cascade either locally in the kidney or at the systemic level may lead to effective treatments for MPGN II.