Background/Aims

The TRPC1 gene on chromosome 3q22–24 resides within the linkage region for diabetic nephropa-thy (DN) in type 1 (T1D) and type 2 diabetes mellitus (T2D). A recent study has demonstrated that TRPC1 expression is reduced in the kidney of diabetic ZDF- and STZ-treated rats. The present study aimed to evaluate the genetic and functional role of TRPC1 in the development of DN.

Methods

Genetic association study was performed with two independent cohorts, including 1,177 T1D European Americans with or without DN from GoKinD population and 850 African-American subjects with T2D-associated end-stage renal disease (ESRD), or with hypertensive (non-diabetic) ESRD, and nondiabetic controls. Seven tag SNP markers derived from HapMap data (phase II) were genotyped. TRPC1 gene expression was examined using real time RT-PCR.

Results

No significant association of TRPC1 DNA polymorphisms with DN or ERSD was found in GoKinD and African-American populations. TRPC1 gene mRNA expression in kidney was found to be trendily reduced in 12-week and significantly in 26-week-old db/db mice.

Conclusions

TRPC1 genetic polymorphism may not fundamentally contribute to the development of DN, while reduction of the gene expression in kidney may be a late phenomenon of DN as seen in diabetic animal models.

Background

Conditionally immortalized podocytes are valuable research tools but are difficult to efficiently transfect and do not provide graded transgene expression.

Methods

Conditionally immortalized mouse podocyte cell lines were established employing a tetracycline-inducible system. Glomerular cells, isolated from transgenic mice bearing two transgenes, NPHS2-reverse tetracycline-controlled transactivator, rtTA (A transgene) and H2-Kb-thermosensitive SV40 T, ts58A (I transgene), were cloned. One clone (AI podocytes) expressing WT1 and synaptopodin was transfected with pBI-EGFP (enhanced green fluorescent protein, G transgene) and separately with ptTS-Neo (transcriptional suppressor, T transgene) to produce stable transformants, AIG podocytes and AIT podocytes.

Results

AIG podocytes expressed EGFP at 33 and 37°C after doxycycline treatment, and retained podocin and rtTA mRNA expression and temperature-sensitive growth regulation. AIT podocytes, transiently transfected with luciferase-BI-EGFP (LG transgene), showed reduced background expression of EGFP and luciferase in the absence of doxycycline. In AITLG podocytes, generated by stable transfection of AIT podocytes with the LG transgene, luciferase expression was tightly regulated by doxycycline in a time- and concentration-dependent manner both at 33 and 37°C, although background expression was not entirely eliminated. These podocytes retained temperature-sensitive growth regulation and expression of podocyte differentiation markers.

Conclusion

Mouse podocytes expressed tetracycline-induced transgenes efficiently while retaining differentiation markers.

Background/Aim:

In in vitro studies, angiotensin (Ang) II has been demonstrated to promote podocyte apoptosis. The present study evaluates the effects of Ang II infusion in rats on podocyte nephrin expression and apoptosis and the molecular mechanisms involved in Ang II-induced proteinuria and mesangial expansion.

Methods:

Sprague-Dawley rats were randomly assigned to receive either normal saline or Ang II (400 ng·kg−1·min−1) by means of a mini-osmotic pump for variable time periods. Systolic blood pressure and urinary protein and albumin excretion rate measurements were carried out on days 7, 14, 21, and 28. The animals were sacrificed on days 14 and 28 and evaluated for serum creatinine, renal pathological changes, podocyte apoptosis, renal nephrin mRNA, and protein expression.

Results:

The Ang II-infused rats developed hypertension and proteinuria. On day 14, the Ang II-infused rats showed narrowing of the slit diaphragm, an increase in podocyte nephrin mRNA and protein expression, and alterations in its distribution along the foot processes. On day 28, the Ang II-infused rats demonstrated the presence of apoptotic podocytes and decreased nephrin mRNA and protein expression. There was a negative correlation between nephrin expression and the numbers of apoptotic podocytes (r = −0.63, p < 0.05).

Conclusion:

These results suggest that changes in nephrin expression may play a role in the pathogenesis of Ang II-induced podocyte apoptosis.

Background/Aims

Several inflammatory biomarkers have been found to be associated with cardiovascular disease or all-cause mortality in dialysis patients, but their usefulness in clinical practice or as surrogate endpoints is not certain. The purpose of the present study was to determine the intrapatient variation of C-reactive protein, IL-6, fetuin-A and albumin in a population of dialysis patients.

Methods

Apparently healthy dialysis patients with either a tunneled dialysis catheter or fistula had monthly assessments of these biomarkers for a total of four determinations, and the intraclass correlation coefficients were calculated as measures of intersubject variance.

Results

Our results showed large within-subject variation relative to the total variation in the measurements (31-46%). Having a tunneled catheter as opposed to a fistula was not significantly associated with mean levels, suggesting that chronic subclinical catheter infection does not explain the variation seen in the biomarkers. In contrast, there was a rapid change in these biomarkers with a clinically apparent acute infection.

Conclusion

These results suggest that these biomarkers have limitations for use as surrogate endpoints in clinical trials due to wide fluctuations, even in apparently clinically healthy individuals.

Background/Aims

The TRPC1 gene on chromosome 3q22–24 resides within the linkage region for diabetic nephropathy (DN) in type 1 (T1D) and type 2 diabetes mellitus (T2D). A recent study has demonstrated that TRPC1 expression is reduced in the kidney of diabetic ZDF- and STZ-treated rats. The present study aimed to evaluate the genetic and functional role of TRPC1 in the development of DN.

Methods

Genetic association study was performed with two independent cohorts, including 1,177 T1D European Americans with or without DN from GoKinD population and 850 African-American subjects with T2D-associated end-stage renal disease (ESRD), or with hypertensive (non-diabetic) ESRD, and nondiabetic controls. Seven tag SNP markers derived from HapMap data (phase II) were genotyped. TRPC1 gene expression was examined using real time RT-PCR.

Results

No significant association of TRPC1 DNA polymorphisms with DN or ERSD was found in GoKinD and African-American populations. TRPC1 gene mRNA expression in kidney was found to be trendily reduced in 12-week and significantly in 26-week-old db/db mice.

Conclusions

TRPC1 genetic polymorphism may not fundamentally contribute to the development of DN, while reduction of the gene expression in kidney may be a late phenomenon of DN as seen in diabetic animal models.

Background

Conditionally immortalized podocytes are valuable research tools but are difficult to efficiently transfect and do not provide graded transgene expression.

Methods

Conditionally immortalized mouse podocyte cell lines were established employing a tetracycline-inducible system. Glomerular cells, isolated from transgenic mice bearing two transgenes, NPHS2-reverse tetracycline-controlled transactivator, rtTA (A transgene) and H2-Kb-thermosensitive SV40 T, ts58A (I transgene), were cloned. One clone (AI podocytes) expressing WT1 and synaptopodin was transfected with pBI-EGFP (enhanced green fluorescent protein, G transgene) and separately with ptTS-Neo (transcriptional suppressor, T transgene) to produce stable transformants, AIG podocytes and AIT podocytes.

Results

AIG podocytes expressed EGFP at 33 and 37°C after doxycycline treatment, and retained podocin and rtTA mRNA expression and temperature-sensitive growth regulation. AIT podocytes, transiently transfected with luciferase-BI-EGFP (LG transgene), showed reduced background expression of EGFP and luciferase in the absence of doxycycline. In AITLG podocytes, generated by stable transfection of AIT podocytes with the LG transgene, luciferase expression was tightly regulated by doxycycline in a time- and concentration-dependent manner both at 33 and 37°C, although background expression was not entirely eliminated. These podocytes retained temperature-sensitive growth regulation and expression of podocyte differentiation markers.

Conclusion

Mouse podocytes expressed tetracycline-induced transgenes efficiently while retaining differentiation markers.

Background/Aims

Several inflammatory biomarkers have been found to be associated with cardiovascular disease or all-cause mortality in dialysis patients, but their usefulness in clinical practice or as surrogate endpoints is not certain. The purpose of the present study was to determine the intrapatient variation of C-reactive protein, IL-6, fetuin-A and albumin in a population of dialysis patients.

Methods

Apparently healthy dialysis patients with either a tunneled dialysis catheter or fistula had monthly assessments of these biomarkers for a total of four determinations, and the intraclass correlation coefficients were calculated as measures of intersubject variance.

Results

Our results showed large within-subject variation relative to the total variation in the measurements (31–46%). Having a tunneled catheter as opposed to a fistula was not significantly associated with mean levels, suggesting that chronic subclinical catheter infection does not explain the variation seen in the biomarkers. In contrast, there was a rapid change in these biomarkers with a clinically apparent acute infection.

Conclusion

These results suggest that these biomarkers have limitations for use as surrogate endpoints in clinical trials due to wide fluctuations, even in apparently clinically healthy individuals.

Background/Aim

In in vitro studies, angiotensin (Ang) II has been demonstrated to promote podocyte apoptosis. The present study evaluates the effects of Ang II infusion in rats on podocyte nephrin expression and apoptosis and the molecular mechanisms involved in Ang II-induced proteinuria and mesangial expansion.

Methods

Sprague-Dawley rats were randomly assigned to receive either normal saline or Ang II (400 ng·kg–1·min–1) by means of a mini-osmotic pump for variable time periods. Systolic blood pressure and urinary protein and albumin excretion rate measurements were carried out on days 7, 14, 21, and 28. The animals were sacrificed on days 14 and 28 and evaluated for serum creatinine, renal pathological changes, podocyte apoptosis, renal nephrin mRNA, and protein expression.

Results

The Ang II-infused rats developed hypertension and proteinuria. On day 14, the Ang II-infused rats showed narrowing of the slit diaphragm, an increase in podocyte nephrin mRNA and protein expression, and alterations in its distribution along the foot processes. On day 28, the Ang II-infused rats demonstrated the presence of apoptotic podocytes and decreased nephrin mRNA and protein expression. There was a negative correlation between nephrin expression and the numbers of apoptotic podocytes (r = −0.63, p < 0.05).

Conclusion

These results suggest that changes in nephrin expression may play a role in the pathogenesis of Ang II-induced podocyte apoptosis.

Background

Gentamicin, a well-known nephrotoxic drug, affects calcium and magnesium homeostasis. Although gentamicin induces urinary calcium and magnesium wasting immediately, it rarely causes significant hypocalcemia or hypomagnesemia clinically.

Methods

We conducted an animal study to investigate the renal adaptation in calcium and magnesium handling after gentamicin treatment and effects on the expression of calcium and magnesium transport molecules in distal tubule. Gentamicin (40 mg/kg) was injected daily in male Sprague-Dawley rats (220–250 g) for up to 7 days.

Results

This treatment did not affect serum creatinine, calcium, or magnesium levels. Gentamicin induced significant hypercalciuria (14-fold) and hypermagnesiuria (10-fold) in 6 h, which was associated with upregulation of TRPV5 (175 ± 3%), TRPV6 (170 ± 4%), TRPM6 (156 ± 4%) and calbindin-D28k (174 ± 3%; all p < 0.05 vs. control). This gene upregulation was maintained with daily injection of gentamicin for 7 days. The gentamicin-induced urinary calcium loss was reduced by 80% at days 3 and 7, while magnesium loss was reduced by 52 and 57% at days 3 and 7, respectively. On the other hand, urinary loss of potassium became worse on day 7 (2-fold), and phosphorus loss worse from day 3 to day 7 (3-fold).

Conclusion

There is a rapid adaptation to gentamicin-induced hypercalciuria and hypermagnesiuria. The upregulation of distal tubule transport molecules, TRPV5, TRPV6, TRPM6 and calbindin-D28k occurs within 6 h of gentamicin treatment. This renal adaptation prevents further mineral loss due to gentamicin treatment.

Background

Clinical practice guidelines recommend alkali therapy in patients with non-dialysis-dependent chronic kidney disease (CKD) and metabolic acidosis to prevent complications from metabolic acidosis. We systematically reviewed the effect of sodium bicarbonate on benefits and harms in patients with CKD.

Methods

We searched for randomized controlled trials in MEDLINE (through July 2011), Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and scientific abstracts. We included trials that compared sodium bicarbonate to standard-of-care therapy or placebo that reported on kidney-related outcomes. We performed random-effects model meta-analyses to compute net changes (for continuous variables) and risk ratios (for binary variables).

Results

Two short-term (≤7 days) crossover trials and 4 long-term (≥2 months) parallel design randomized controlled trials met eligibility (312 patients). All 6 trials prescribed sodium bicarbonate in the alkali-treated group. In the long-term studies, alkali therapy was associated with a net decrease in serum creatinine (−0.07 mg/dL, 95% CI −0.09, −0.05, P<0.001; I2=0), a net improvement in GFR (3.2 mL/min/1.73 m2, 95% CI 1.6, 4.7, P<0.001; I2=0), and a lower incidence of dialysis initiation (risk ratio 0.21, 95% CI 0.08, 0.54; P=0.001; I2=0). No benefit was observed on the serum creatinine or GFR in short-term studies. Alkali therapy was not associated with a higher likelihood of initiating or escalating anti-hypertensive medications.

Conclusions

Alkali therapy is associated with an improvement in kidney function, which may afford a long-term benefit in slowing the progression of CKD. However, differences in study protocols and small sample sizes preclude definitive conclusions.

Background/Aims

Arteriovenous fistulas (AVFs) appear to be clinically superior to catheters as vascular access for maintenance hemodialysis, but higher insertion costs and high disease burden and mortality obscure the issue of whether AVF placement before hemodialysis initiation represents a net cost savings. We aimed to investigate Medicare costs for patients beginning maintenance hemodialysis, as related to timing of arteriovenous fistula (AVF) placement.

Methods

Data were from Medicare claims for incident hemodialysis patients aged ≥ 67 years in 2006. The study period extended from two years before to one year after dialysis initiation. Patients identified as having AVFs were categorized by timing of placement (mature AVF at dialysis initiation, maturing AVF at initiation, post-initiation AVF placement). Because timing may be influenced by factors that also influence overall costs, the model accounted for this non-random treatment assignment. An ordered probit extension of the classic Heckman correction was employed after identifying an appropriate instrumental variable. A cohort with Medicare coverage before and after dialysis initiation was identified, and Medicare claims were used to identify comorbid conditions and treatment costs.

Results

Principal findings are that earlier AVF placement leads to lower costs, with the potential for about $500 million in savings. Additionally, the effect of non-random treatment assignment is real and significant. In our data, the impact of AVF placement timing was understated when treatment selection was ignored.

Conclusions

For appropriate AVF candidates, having a mature AVF in place at the time of dialysis initiation appears to confer a cost savings.

Background/Aims

Intravenous (IV) iron preparations are widely used in the management of anemia in ESRD populations. Recent changes in reimbursement policy have dramatically increased the use of IV iron to lower the use of costly erythropoiesis-stimulating agents. These preparations are frequently administered with insufficient attention to the total body iron stores or presence of inflammation which is aggravated by excess iron. Endothelial injury and dysfunction are critical steps in atherosclerosis, thrombosis and cardiovascular disease. IV iron preparations raise plasma non-transferrin-bound iron which can promote oxidative stress, endothelial damage and dysfunction. We explored the effect of an IV iron preparation on endothelial cells, monocytes and isolated arteries.

Methods

Primary cultures of human aortic endothelial cells (HAEC) were treated with pharmacologically relevant concentrations of iron sucrose (10–100 μg/ml) for 4–24 h. Endothelial cell morphology, viability, and monocyte adhesion were tested. Endothelial function was assessed by measuring the vasorelaxation response to acetylcholine in normal rat thoracic aorta rings preincubated with iron sucrose (200 μg/ml).

Results

In contrast to the control HAEC which showed normal cobblestone appearance, cells treated with iron sucrose (50–100 μg/ml) for 4 h showed loss of normal morphological characteristics, cellular fragmentation, shrinkage, detachment, monolayer disruption and nuclear condensation/fragmentation features signifying apoptosis. HAEC exposure to iron sucrose (10–100 μg/ml) increased monocyte adhesion 5- to 25-fold. Incubation in media containing 200 μg/ml iron sucrose for 3 h caused marked reduction in the acetylcholine-mediated relaxation in phenylephrine-precontracted rat aorta.

Conclusion

Pharmacologically relevant concentration of iron sucrose results in endothelial injury and dysfunction and marked increase in monocyte adhesion.

Background

Awareness of chronic kidney disease (CKD) is low. Efforts are underway to increase recognition of CKD among patients, assuming that such an increase will lead to better outcomes through greater adherence to proven therapies. Few studies have tested this assumption.

Methods

CKD awareness, defined by a ‘yes’ answer to ‘Have you ever been told by a healthcare provider you have weak or failing kidneys?’, was assessed among 2,404 adults with CKD stages 1–4, who participated in the 2003–2008 National Health and Nutrition Examination Surveys. Odds of blood pressure (BP) control, self-reported use of angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB), and glycemic control, were determined among those aware vs. unaware of their CKD.

Results

Optimal BP control, ACEI/ARB use and glycemic control were low in the US adult population with CKD, although there was a recent increase in attainment of guideline-concordant BP control. Odds of BP control and ACEI/ARB use were not different among individuals aware of their CKD compared to those unaware (adjusted odds ratio (AOR) 0.91; 95% CI 0.52–1.58 and AOR 0.75; 0.44–1.30, respectively). CKD awareness among diabetic participants was not associated with glycemic control (AOR 0.41; 95% CI 0.14–1.18).

Conclusion

Awareness of CKD is not associated with more optimal BP control, ACEI/ARB use or glycemic control. Future efforts in this area should further explore the measurement of CKD awareness and behaviors associated with CKD awareness.

Background

The relationship of routine postoperative troponin I (TnI) monitoring in kidney transplant recipients and in-hospital myocardial infarction (MI) is not known.

Methods

This observational study evaluated the prevalence of abnormal postoperative TnI (Ortho Clinical Diagnostics assay) in 376 consecutive kidney or kidney/pancreas transplant recipients. In-hospital MI was adjudicated using the universal definition. Rates of death and coronary revascularizations at 1 year were studied. Logistic regression analysis was performed to identify independent predictors of abnormal TnI.

Results

Ninety-five (25%) recipients had abnormal TnI (>0.04 ng/ml) following transplantation. Abnormal TnI levels were more common in older (mean age: 52.2 ± 13.4 vs. 48.3 ± 13.2 years, p = 0.01), diabetic (57.9 vs. 45.6%, p = 0.04), and prior coronary artery disease (31.6 vs. 20.3%, p = 0.02) patients. In-hospital MI occurred in 6 patients (1.6%). All subsequent in-hospital cardiovascular events occurred in the abnormal postoperative TnI group; most in those with TnI levels >1 ng/ml. Previous coronary artery disease was the only independent predictor of a postoperative TnI level >1 ng/ml in multivariate analysis (odds ratio 4.61, 95% confidence interval 1.49–14.32). At 1 year there was no significant difference in death (3.2 vs. 1.8%, p = 0.42) and borderline significant difference in coronary revascularization (5.3 vs. 1.4%, p = 0.049) in abnormal versus normal TnI groups.

Conclusions

In-hospital MI was infrequent, but abnormal TnI highly prevalent following renal transplantation. Normal TnI levels following renal transplantation had a high negative predictive value in excluding patients likely to develop subsequent postoperative MI. The role of a higher TnI cut-off for screening for postoperative MI in high-risk subgroups deserves future prospective evaluation.

Background

Inflammation is thought to play a role in ischemic acute kidney injury (AKI). We have demonstrated that macrophage and dendritic cell depletion, using liposome-encapsulated clodronate (LEC), is protective against ischemic AKI.

Methods

To determine whether macrophages or dendritic cells or both play a role in ischemic AKI, we performed ischemic AKI in CD11b-DTR mice that have a diphtheria toxin (DT)-induced depletion of CD11b cells (macrophages) and CD11c-DTR mice that have a DT-induced depletion of CD11c cells (dendritic cells).

Results

While LEC-treated animals had a significant functional protection from AKI, CD11b-DTR and CD11c-DTR mice were not protected against AKI despite a similar degree of renal macrophage and dendritic cell depletion. Proinflammatory cytokines are known to play a role in ischemic AKI. To determine the possible reasons for the lack of protection in CD11b-DTR and CD11c-DTR mice compared to LEC-treated mice, 32 cytokines/chemokines were measured in these mice. Of the cytokines/chemokines measured, IL-6, MCP-1, GMCSF, IL-1β and CXCL1 (also known as IL-8 in humans or KC in mice) showed significant differences in the LEC-treated, CD11b-DTR and CD11c-DTR mice. MCP-1 and CXCL1 (known mediators of AKI), and also GMCSF and IL-1β were increased in AKI and decreased in LEC-treated AKI but not AKI in CD11b-DTR or CD11c-DTR mice. Conclusions: These findings suggest that LEC-mediated protection from AKI is not simply mediated by depletion of renal macrophage or dendritic cell subpopulations. Protection against AKI in LEC-treated compared to CD11b-DTR or CD11c-DTR mice may be partially explained by differences in proinflammatory cytokine profiles.

Background

Chronic kidney disease (CKD) is a major public health problem, and despite continued research in the field, there is still a need to identify both biomarkers of risk and progression, as well as potential therapeutic targets. Structural equation modeling (SEM) is a family of statistical techniques that has been utilized in the fields of sociology and psychology for many years; however, its utilization in the biological sciences is relatively novel. SEM's ability to investigate complex relationships in an efficient, single model could be utilized to understand the progression of CKD, as well as to develop a predictive model to assess kidney status in the patient.

Methods

Fischer 344 rats were fed either an ad libitum diet or a calorically restricted diet, and a time-course study of kidney structure and function was performed. EQS, a SEM software package, was utilized to generate five CKD models of the Fisher 344 rat and identify relationships between measured variables and estimates of kidney damage and kidney function.

Results

All models identified strong relationships between a biomarker for CKD, kidney injury molecule-1 (Kim-1) and kidney damage, in the Fischer 344 rat CKD model. Models also indicate a strong relationship between age and renal damage and dysfunction.

Conclusion

SEM can be used to model CKD and could be useful to examine biomarkers in CKD patients.

Background

Several studies have shown an association between erythropoietin-stimulating agent (ESA) responsiveness and mortality in chronic kidney disease (CKD) patients. In our present study, we examined the association between prescribed ESA dose and mortality in peritoneal dialysis (PD) and hemodialysis (HD) patients. We hypothesized that PD patients received lower ESA dose for the same achieved hemoglobin compared to HD patients and that ESA dose-mortality associations were different between PD and HD patients.

Methods

We compared the prescribed doses of ESA between 139,103 HD and 10,527 PD patients treated in DaVita dialysis clinics from 7/2001 through 6/2006 using adjusted Poisson regression and examined mortality-predictability of prescribed ESA dose and ESA responsiveness index (ESA/hemoglobin) in PD and HD with follow-up through 6/2007 using Cox regression models.

Results

Poisson adjusted ratio of ESA dose of HD to PD was 3.6 (95% CI 3.5–3.7). In PD patients, adjusted all-cause death hazard ratios (HR) for ESA doses of 3,000–5,999, 6,000–8,999 and ≥9,000 U/week (reference <3,000 U/week) were 0.97 (0.87–1.07), 0.85 (0.76–0.95) and 1.08 (0.98–1.18), respectively; whereas in HD patients across commensurate ESA dose increments of 10,000–19,999, 20,000–29,999 and ≥30,000 U/week (reference <10,000 U/week) were 1.14 (1.11–1.17), 1.54 (1.50–1.58) and 2.15 (2.10–2.21), respectively. In PD and HD patients, the adjusted death HR of the 4th to 1st quartile of ESA responsiveness index were 1.14 (1.04–1.26) and 2.37 (2.31–2.43), respectively.

Conclusions

Between 2001 and 2006, most PD patients received substantially lower ESA dose for same achieved hemoglobin levels, and low ESA responsiveness was associated with higher mortality in both HD and PD patients.

Background

Low physical activity (PA) has been associated with higher rates of cardiovascular disease (CVD) and mortality in the general population. Despite the benefits of kidney transplantation, kidney transplant recipients (KTRs) remain at elevated risk for CVD and mortality compared to individuals without kidney disease.

Methods

A prospective cohort of 507 adult KTRs from three academic centers completed the Physical Activity Scale for the Elderly (PASE) at transplantation. PASE scores were divided into tertiles.

Results

PA was lower with older age, history of CVD, smoking, and diabetes. During the median 8-year follow-up period, 128 individuals died, among whom 101 had a functioning allograft. In multivariable Cox regression for all-cause mortality, greater PA was strongly associated with better survival (HR: 0.52 for most active vs. inactive tertiles, 95% CI: 0.31–0.87, p = 0.01). Secondary analyses, in which (1) death with a functioning graft was the primary outcome, and (2) PASE scores were converted to the metabolic equivalent of task, revealed similar results. We did not find an association between change of PA after transplantation and mortality.

Conclusions

PA at the time of kidney transplantation is a strong predictor of all-cause mortality and death with graft function. Evaluation of PA level among kidney transplant candidates may be a useful method to risk-stratify patients for survival after kidney transplantation. Kidney transplant candidates and recipients should also be encouraged to be physically active.

Background/Aims

Reduced renal L-arginine (L-Arg) synthesis/transport, induction of arginases and increased endogenous NOS inhibitor, asymmetric dimethylarginine (ADMA) will inhibit NO production. This study investigated pathways of L-Arg synthesis/uptake/utilization, ADMA degradation and oxidant/antioxidants in puromycin aminonucleoside (PAN) chronic kidney disease (CKD).

Methods

Rats were given low- (LD) or high-dose (HD) PAN and followed for 11 weeks for proteinuria. BP was measured and blood and tissues were harvested and analyzed for abundance of argininosuccinate synthase (ASS) and lyase (ASL), arginase, cationic amino acid transporter (CAT1) and dimethylargininedimethylaminohydrolase (DDAH) in kidney, cortex, aorta and liver. Arginase and DDAH activity, plasma L-Arg and ADMA, renal pathology and creatinine clearances were also measured.

Results

PAN caused dose-dependent kidney damage and hypertension and creatinine clearance fell in HD-PAN. Renal ASS fell in HD-PAN, renal cortex and aortic ASL and membrane CAT1 fell in both PAN groups. There was no activation of renal arginase, but aortic arginase increased in LD-PAN. Renal DDAH activity fell moderately in LD-PAN and markedly in HD-PAN where hepatic DDAH activity also fell. Plasma L-Arg was unchanged while ADMA rose moderately and dose-dependently with PAN. There were several indices of oxidative stress which was most prominent in HD-PAN.

Conclusion

Reduction in renal ASS/ASL and loss of renal cortex CAT1 compromises renal L-Arg synthesis and release. Loss of aortic CAT1 impairs L-Arg uptake. Increased plasma ADMA was associated with progressive loss of renal DDAH activity. However, loss of renal clearance and falls in hepatic DDAH activity in HD-PAN did not have additive effects on plasma ADMA.

Background and Aims

Cognitive impairment is a risk factor for death in dialysis patients and the general population. We sought to determine if cognitive impairment is associated with death in people with non-dialysis-dependent chronic kidney disease (CKD), and if so, whether this relationship is greater in the CKD population compared to the general population.

Methods

National Health and Nutrition Examination Survey-III participants older than 60 years were asked to subtract 3 from 20 five times and to perform immediate and delayed recall of three items. A cognitive score of 0–11 was assigned based on the number of correct responses. Participants were categorized according to cognitive score (11, 9–10, 6–9, and 0–5) and CKD status. Survival analyses were conducted using Cox models.

Results

Within the CKD subpopulation, those in the lowest cognitive score group had a twofold increased hazard of death compared to those with maximum score. Within the non-CKD subpopulation, those in the lowest cognitive score group had a 46% increased hazard of death compared to those with maximum score. However, the difference in the hazards of death in the CKD and non-CKD subpopulations with the lowest cognitive score was not significant (p = 0.99).

Conclusions

Low cognitive score is associated with an increased risk of death in elderly individuals with and without CKD; however, there was no interaction of CKD and low cognitive score in this analysis.

Background/Aims

Living donor nephrectomy can be associated with increases in blood pressure several years following the procedure, but the best method to assess blood pressure during the living donor evaluation process is unclear.

Methods

Living kidney donors underwent casual clinic and ambulatory blood pressure monitoring (ABPM) and measurement of central aortic pressures at baseline and 6 months following donor nephrectomy.

Results

There was a significant decline in clinic systolic blood pressure (SBP; p = 0.001) and central aortic systolic pressure (p = 0.011) during the study period. However, average ABPM was unchanged and other measures of central arterial pressures and Augmentation Index were unchanged at 6 months compared to baseline.

Conclusions

The remarkable differences between clinic SBP and ambulatory SBP prior to donation, and the disappearance of these differences 6 months later, suggest a substantial white coat effect on SBP associated with living kidney donor evaluation. Also, ABPM represents a better way to assess blood pressure prior to kidney donation.

Background/Aims

The mammalian target of rapamycin (mTOR) is a serine kinase that regulates phosphorylation (p) of its target ribosomal S6 kinase (S6K1), whose activation can lead to glomerular and proximal tubular cell (PTC) injury and associated proteinuria. Increased mTOR/S6K1 signaling regulates signaling pathways that target fibrosis through adherens junctions. Recent data indicate aldosterone signaling through the mineralocorticoid receptor (MR) can activate the mTOR pathway. Further, antagonism of the MR has beneficial effects on proteinuria that occur independent of hemodynamics.

Methods

Accordingly, hypertensive transgenic TG(mRen2)27 (Ren2) rats, with elevated serum aldosterone and proteinuria, and age-matched Sprague-Dawley rats were treated with either a low dose (1 mg/kg/day) or a conventional dose (30 mg/kg/day) of spironolactone (MR antagonist) or placebo for 3 weeks.

Results

Ren2 rats displayed increases in urine levels of the PTC brush border lysosomal enzyme N-acetyl-β-aminoglycosidase (β-NAG) in conjunction with reductions in PTC megalin, the apical membrane adherens protein T-cadherin and basolateral α-(E)-catenin, and fibrosis. In concert with these abnormalities, Ren2 renal cortical tissue also displayed increased Ser2448 (p)/activation of mTOR and Thr389 (p)-S6K1 and increased 3-nitrotyrosine (3-NT) content, a marker for peroxynitrite. Low-dose spironolactone had no effect on blood pressure but decreased proteinuria and β-NAG comparable to a conventional dose of this MR antagonist. Both doses of spironolactone attenuated ultrastructural maladaptive alterations and led to comparable reductions in (p)-mTOR/(p)-S6K1, 3-NT, fibrosis, and increased expression of α-(E)-catenin, T- and N-cadherin.

Conclusions

Thereby, MR antagonism improves proximal tubule integrity by targeting mTOR/S6K1 signaling and redox status independent of changes in blood pressure.

Background: Whether lipoprotein-associated phospholipase A2 (Lp-PLA2) levels are associated with kidney function decline has not been well studied. Methods: We investigated associations of Lp-PLA2 antigen and activity with kidney function decline and rapid decline over 5.7 years in the Cardiovascular Health Study (n = 4,359). We estimated kidney function by cystatin C (eGFRcys) in repeated measures, and defined rapid decline as ≥3 ml/min/1.73 m2 per year. We stratified by baseline preserved GFR (≥60 ml/min/1.73 m2). Results: Mean age was 72 ± 5 years. Average eGFRcys decline was −1.79 ml/min/1.73 m2 (SD = 2.60) per year. Among persons with preserved GFR, compared to the lowest quartile of Lp-PLA2 antigen, eGFRcys decline was faster among persons in the second, β −0.31 (95% CI −0.52, −0.10), third −0.19 (–0.41, 0.02) and fourth quartiles −0.26 (–0.48, −0.04) after full adjustment. Persons in the highest quartile of Lp-PLA2 antigen had increased odds of rapid decline 1.34 (1.03, 1.75), compared to the lowest. There was no significant association between levels of Lp-PLA2 activity and eGFRcys decline or rapid decline. Associations were not statistically significant among persons with low eGFR (<60 ml/min/1.73 m2) at baseline. Conclusion: Higher levels of Lp-PLA2 antigen but not activity were significantly associated with faster rates of kidney function decline. These findings may suggest a novel vascular pathway for kidney disease progression.

Background/Aims: In an antiglomerular basement membrane glomerulonephritis (GN) model, GN-resistant Lewis (LEW) rats naturally recover from early glomerular inflammation (days 21–23). We have previously identified a glomeruli-infiltrating CD8α+CD11highMHC II+ cell (GIL CD8α+ cell) in GN-prone Wistar Kyoto (WKY) rats, which terminates glomerular inflammation through inducing T cell apoptosis prior to glomerular fibrosis at days 35–40. We investigated if GIL CD8α+ cells were also associated with the recovery in LEW rats. Methods: GIL CD8α+ cells in LEW rats were characterized; their infiltration was observed in connection with T cell apoptosis in glomeruli. Results: An influx of GIL CD8α+ cells into inflamed glomeruli was confirmed in the immunized LEW rats at days 17–22, which was much earlier than days 28–35 in WKY rats. Notably, LEW rats had a GIL CD8α+CD11high subpopulation after day 17, while WKY rats lacked this population until after day 30. Analyses further revealed a large number of clustered apoptotic CD4+ or CD3+ T cells in the glomeruli during recovery (day 23) in LEW rats, as compared to day 35 (transition to fibrosis) in WKY rats. Thus, infiltration of GIL CD8α+ cells coincided with decline of glomerular inflammation and T cell apoptosis during recovery in LEW rats. Isolated GIL CD8α+ cells were able to infiltrate glomeruli in both WKY and LEW rats at day 20. Conclusion: Our data revealed a strong association between GIL CD8a+ cells and recovery from early glomerular inflammation. It raises a possibility of involvement of GIL CD8a+ cells in the recovery.

Introduction

Alemtuzumab and rabbit antithymocyte globulin (rATG) are being used with increasing frequency as induction agents in kidney transplantation. Using the US Renal Data Base System, we analyzed the safety profile of these agents in the elderly.

Methods

In a cohort of patients transplanted from January 2000 to July 2009 and followed through 2009, we assessed the effect of induction on allograft loss and death among elderly recipients. Recipients were censored at dates of allograft loss, death or the end of study. Independent associations between induction agents and allograft loss or death were examined using multivariate analysis with forward stepwise Cox regression.

Results

Among 130,402 patients with first transplants, 14,907 were age 65 years or older. 4,466 (30%), 3,049 (20.5%), 1,501 (10.1%), and 999 (6.7%) were induced with thymoglobulin, basiliximab, daclizumab, and alemtuzumab, respectively. After adjusting for baseline differences, induction with alemtuzumab was associated with an increased risk of graft loss and death, with an adjusted hazard ratio (AHR) of 1.26 (95% CI 1.08–1.48). Risk was also present at other age cutoffs [age >60 (AHR 1.16; 95% CI 1.03–1.31; p = 0.014), age >70 (AHR 1.43; 95% CI 1.13–1.81; p = 0.003) and age >75 (AHR 1.68; 95% CI 1.07–2.63; p = 0.024)].

Conclusions

In the elderly, alemtuzumab is associated with an escalating risk of death and graft loss in recipients of kidney transplantations.