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BACKGROUND: Timely detection of acute kidney injury (AKI) in hospital patients has been hampered by the multiple definitions of AKI and difficulties applying their criteria. A laboratory delta check may provide an effective means of detecting patients developing AKI. This study compared three of the proposed AKI definitions and a delta check to detect AKI using serum creatinine results of hospital inpatients. METHODS: Serum creatinine results for 2822 inpatients were gathered retrospectively from the clinical biochemistry database. All serum creatinine results within 30 d of admission were included for each patient and assessed for AKI according to four criteria: Risk, Injury, Failure (RIFLE), Acute Kidney Injury Network (AKIN), Waikar & Bonventre or a delta check (increase of >26 [mu]mol/L between two successive values). RESULTS: A total of 149 (11.3%) patients were defined as having AKI by at least one of the four criteria. Different populations of patients were identified by each criterion. The number of patients identified and the incidence of AKI were as follows: RIFLE 94 (7.1%), AKIN 125 (9.5%), Waikar & Bonventre 100 (7.6%) and delta check 146 (11.1%). The delta check detected 132 (98%) of all 135 cases detected by the other three criteria. A further 14 patients were detected solely by the delta check. CONCLUSIONS: The different definitions proposed for AKI detect different populations of patients. A laboratory delta check detected 98% of all the patients identified by AKIN, RIFLE and Waikar & Bonventre combined and could therefore provide a practical way of detecting AKI patients. [ABSTRACT FROM AUTHOR]

Background: Acute kidney injury in hospital patients is common and associated with reduced survival and higher healthcare costs. The Tackling Acute Kidney Injury (TAKI) quality improvement project aimed to reduce mortality rates in patients with acute kidney injury by implementing a multicomponent intervention comprising of an electronic alert, care bundle and education in five UK hospitals across a variety of wards. A parallel developmental evaluation using a case study approach was conducted to provide the implementation teams with insights into factors that might impact intervention implementation and fidelity. The qualitative element of the evaluation will be reported., Methods: 29 semi-structured interviews with implementation teams across the five hospitals were carried out to identify perceived barriers and enablers to implementation. Interviews were taped and transcribed verbatim and Framework analysis was conducted., Results: Interviews generated four 'barriers and enablers' to implementation themes: i) practical/contextual factors, ii) skills and make-up of the TAKI implementation team, iii) design, development and implementation approach, iv) staff knowledge, attitudes, behaviours and support. Enablers included availability of specialist teams (e.g. educational teams), multi-disciplinary implementation teams with strong leadership, team-based package completion and proactive staff. Barriers were frequently the converse of facilitators., Conclusions: Despite diversity of sites, a range of common local factors-contextual, intervention-based and individual-were identified as potential barriers and enablers to fidelity, including intervention structure/design and process of/approach to implementation. Future efforts should focus on early identification and management of barriers and tailored optimisation of known enablers such as leadership and multidisciplinary teams to encourage buy-in. Improved measures of real-time intervention and implementation fidelity would further assist local teams to target their support during such quality improvement initiatives., Competing Interests: The authors have declared that no competing interests exist.

Background: Variable standards of care may contribute to poor outcomes associated with AKI. We evaluated whether a multifaceted intervention (AKI e-alerts, an AKI care bundle, and an education program) would improve delivery of care and patient outcomes at an organizational level., Methods: A multicenter, pragmatic, stepped-wedge cluster randomized trial was performed in five UK hospitals, involving patients with AKI aged ≥18 years. The intervention was introduced sequentially across fixed three-month periods according to a randomly determined schedule until all hospitals were exposed. The primary outcome was 30-day mortality, with pre-specified secondary endpoints and a nested evaluation of care process delivery. The nature of the intervention precluded blinding, but data collection and analysis were independent of project delivery teams., Results: We studied 24,059 AKI episodes, finding an overall 30-day mortality of 24.5%, with no difference between control and intervention periods. Hospital length of stay was reduced with the intervention (decreases of 0.7, 1.1, and 1.3 days at the 0.5, 0.6, and 0.7 quantiles, respectively). AKI incidence increased and was mirrored by an increase in the proportion of patients with a coded diagnosis of AKI. Our assessment of process measures in 1048 patients showed improvements in several metrics including AKI recognition, medication optimization, and fluid assessment., Conclusions: A complex, hospital-wide intervention to reduce harm associated with AKI did not reduce 30-day AKI mortality but did result in reductions in hospital length of stay, accompanied by improvements in in quality of care. An increase in AKI incidence likely reflected improved recognition., (Copyright © 2019 by the American Society of Nephrology.)

Introduction: This study investigated outcomes in critically unwell acute kidney injury patients and the role of the National Early Warning Score and other factors in identifying patients who experience negative outcomes., Methods: Retrospective cohort study investigating 64 patients seen by Critical Care Outreach between November 2014 and February 2015. Mortality at one year was analysed using multivariate regression; all other statistical tests were non-parametric., Results: Forty-four per cent of patients required escalation to higher level care, 56% failed to survive beyond one year and 30% of those who did survive had a deterioration in renal function. Previous acute kidney injury significantly predicted mortality but the National Early Warning Score did not. A subgroup of patients developed Stage 3 acute kidney injury before a rise in National Early Warning Score., Conclusions: Acute kidney injury in the Critical Care Outreach patient population is associated with high morbidity and mortality. Previous acute kidney injury and acute kidney injury stage may be superior to the National Early Warning Score at identifying patients in need of Critical Care Outreach review.

Acute kidney injury (AKI) is common among emergency department patients admitted to hospital. There is evidence of inadequate management of the condition leading to adverse outcomes. We present an illustrative case of AKI complicating a gastrointestinal disorder in an older adult. We discuss the clinical presentation, assessment and management of AKI with reference to recent consensus guidelines on classification and treatment., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Background: Significant disparity exists in the United Kingdom between the need for organ transplant and supply of deceased donor organs. In the recent years, efforts to increase donation has improved the rate of mainly deceased donors after circulatory death and from older donors. The rate of donation from pediatric population has remained low and those younger than 2 years including neonatal donation has remained largely unexplored., Methods: A retrospective review of the outcome of renal transplantation from pediatric donor (<18 years) kidneys in the United Kingdom., Results: Our results show a poor referral and conversion rate, and high discard rate (43%) of kidneys procured from donors younger than 2 years. During the 15-year study period (1997-2011), 47 donors younger than 2 years were referred (3 per year). Of these, 26 proceeded to donation resulting in 17 transplants (65% utilization). The referral rate for donors 2 years or older to younger than 5 years also remains low (76 in 15 years), but the conversion (88%) and utilization rates (73%) are better in this group. There was better utilization in donors aged 5 years or older to younger than 18 years. Overall graft and patient survival remains excellent in all 3 groups; with comparable survival of 82%, 85%, and 77% (P = 0.29) with mean follow-up periods of 9, 12.5, and 11.8 years, respectively., Conclusions: Despite excellent outcome, the referral, donation, and utilization of kidneys from donors younger than 5 years and particularly those younger than 2 years remain low. We suggest implementing improved strategies to increase donation from this group of population.

We report the stepwise application of the RIFLE classification in 155,624 admissions in the UK Intensive Care National Audit & Research Centre Case Mix Programme database. The assumptions required to define RIFLE and their relationship with renal replacement therapy (RRT) and ICU mortality were assessed. Previous reports had not explored the method of estimating baseline creatinine, the position of class boundaries, or interactions between urine volume (AKI-U) and the peak/estimated baseline creatinine (AKI-Cr) within 24 h of ICU admission. The risk of developing AKI strongly depended on the assumed GFR increasing from 36 to 58% across the recommended range. AKI-U was often seen without AKI-Cr, and moderate oliguria (under 850 ml/24 h) was a stronger predictor of mortality than any degree of AKI-Cr partly because mortality fell when peak/estimated baseline creatinine ratios exceed fourfold. Mild oliguria (850-1500 ml/24 h) was common (38,928 admissions, 26%) and had a similar association with mortality (relative risk 1.6, 95% CI: 1.5-1.6) as did AKI-Cr defined Failure (risk ratio 1.5, 95% CI: 1.5-1.6). However, AKI-Cr was a strong predictor for RRT, which was used in 17,802 (11%) of admissions. Nearly half (48%) of the Failure patients never received RRT; nonetheless, most (66%) survived critical care. Thus, although the RIFLE classification may be attempted in large population cohorts, there is significant heterogeneity of both renal and, in particular, vital outcomes within each class.

Low-grade proteinuria and systolic hypertension (SHT) are risk factors for allograft failure. Both are dynamic variables and their relationship is not independent. We have simultaneously analyzed the effects of proteinuria and SHT on graft outcomes in 805 adult Kidney Transplant Recipients and impact of their changes over time. Proteinuria and systolic blood pressure (SBP) were recorded for years 1 and 3 posttransplantation. Subjects with proteinuria >1 g/day were excluded. Patients were divided into groups based on proteinuria (Absent(A) <150 mg/day or low-grade(P)150 mg-1 g/day) and blood pressure (Normotensive-SBP <140 mmHg or hypertensive-SBP ≥ 140 mmHg). Graft survival was assessed in all four groups over 10 years by multivariate analysis. At the three annual time points (Year 1, 2 and 3) hypertensive patients with proteinuria had the worst graft survival. Patients with persistent proteinuria between years 1-2 and 2-3 had the poorest graft survival with an improvement if proteinuria regressed (P-A), especially in the Hypertensive group. The impact of proteinuria was highest in persistently hypertensive patients between years 1-3. Thus both proteinuria and SHT were associated with poor graft survival and the combination of the two led to the worst outcomes. Importantly, SHT was associated with significantly worse outcomes in patients with proteinuria. Patient cohort with SHT and low-grade proteinuria represent a selective group that might benefit from intervention., (© Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.)

Background: The use of alemtuzumab as induction immunosuppression for renal transplantation introduces the possibility of long-term tacrolimus monotherapy, avoiding maintenance with both corticosteroids and mycophenolate mofetil (MMF)., Methods: We conducted a single-center, prospective, open-label, randomized controlled trial comparing two steroid avoidance regimens between December 2006 and November 2010. One hundred and sixteen adult patients were randomized to either basiliximab induction followed by tacrolimus and MMF maintenance or to alemtuzumab induction followed by tacrolimus monotherapy. The primary endpoint was noninferiority of isotopic glomerular filtration rate at 1 year; secondary endpoints included patient and graft survival, incidence of delayed graft function, and incidence and severity of biopsy-proven acute rejection., Results: The two groups were well matched for all baseline demographics. Isotopic glomerular filtration rate was comparable between the groups at 1 year (57±26 mL/min for alemtuzumab group and 53±21 mL/min for basiliximab group; P=0.42). Secondary endpoints were also similar between the groups. The rate of biopsy-proven acute rejection by 12 months was lower in the alemtuzumab group (n=6 vs. n=14 in basiliximab arm) just reaching statistical significance (P=0.049); however, a single extra case in the alemtuzumab arm included when considering clinically treated rejection removes this significance (P=0.082). Similar rates of cardiovascular, infective, and neoplastic complications were observed in both groups. Forty-seven (81.0%) of the patients in the alemtuzumab group remained on tacrolimus monotherapy at 12 months., Conclusions: Renal transplantation with alemtuzumab induction followed by tacrolimus monotherapy leads to good graft and patient outcomes, with no major differences detected compared with basiliximab induction and tacrolimus/MMF maintenance at 1 year.

Early identification and prognostic stratification of delayed graft function following renal transplantation has significant potential to improve outcome. Mass spectrometry analysis of serum samples, before and on day 2 post transplant from five patients with delayed graft function and five with an uncomplicated transplant, identified aminoacylase-1 (ACY-1) as a potential outcome biomarker. Following assay development, analysis of longitudinal samples from an initial validation cohort of 55 patients confirmed that the ACY-1 level on day 1 or 2 was a moderate predictor of delayed graft function, similar to serum creatinine, complementing the strongest predictor cystatin C. A further validation cohort of 194 patients confirmed this association with area under ROC curves (95% CI) for day 1 serum (138 patients) of 0.74 (0.67-0.85) for ACY-1, 0.9 (0.84-0.95) for cystatin C, and 0.93 (0.88-0.97) for both combined. Significant differences in serum ACY-1 levels were apparent between delayed, slow, and immediate graft function. Analysis of long-term follow-up for 54 patients with delayed graft function showed a highly significant association between day 1 or 3 serum ACY-1 and dialysis-free survival, mainly associated with the donor-brain-dead transplant type. Thus, proteomic analysis provides novel insights into the potential clinical utility of serum ACY-1 levels immediately post transplantation, enabling subdivision of patients with delayed graft function in terms of long-term outcome. Our study requires independent confirmation.

Worldwide, acute kidney injury (AKI) is associated with poor patient outcomes. Over the last few years, collaborative efforts, enabled by a common definition of AKI, have provided a description of the epidemiology, natural history, and outcomes of this disease and improved our understanding of the pathophysiology. There is increased recognition that AKI is encountered in multiple settings and in all age groups, and that its course and outcomes are influenced by the severity and duration of the event. The effect of AKI on an individual patient and the resulting societal burden that ensues from the long-term effects of the disease, including development of chronic kidney disease (CKD) and end-stage renal disease (ESRD), is attracting increasing scrutiny. There is evidence of marked variation in the management of AKI, which is, to a large extent, due to a lack of awareness and an absence of standards for prevention, early recognition, and intervention. These emerging data point to an urgent need for a global effort to highlight that AKI is preventable, its course is modifiable, and its treatment can improve outcomes. In this article, we provide a framework of reference and propose specific strategies to raise awareness of AKI globally, with the goal to ultimately improve outcomes from this devastating disease.

Background: Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker for acute kidney injury that is beginning to be used in clinical practice in addition to research studies. The current study describes an independent validation and comparison of five commercially available NGAL assays, focusing on urine samples. This is an essential step in the translation of this marker to clinical use in terms of allowing valid inter-study comparison and generation of robust results., Methods: Two CE (Conformité Européenne)-marked assays, the NGAL Test (BioPorto) on Siemens ADVIA(®) 1800 and the ARCHITECT Urine NGAL assay on i2000SR (Abbott Laboratories), and three research-use-only (RUO) ELISAs (R&D Systems, Hycult and BioPorto) were evaluated. Imprecision, parallelism, recovery, selectivity, limit of quantitation (LOQ), vulnerability to interference and hook effect were assessed and inter-assay agreement was determined using 68 urine samples from patients with various renal diseases and healthy controls., Results: The Abbott and R&D Systems assays demonstrated satisfactory performance for all parameters tested. However for the other three assays evaluated, problems were identified with LOQ (BioPorto/ADVIA(®)), parallelism (BioPorto ELISA) or several parameters (Hycult). Between-method agreement varied with the Hycult assay in particular being markedly different and highlighting issues with standardization and form of NGAL measured., Conclusions: Variability exists between the five NGAL assays in terms of their performance and this should be taken into account when interpreting results from the various clinical or research studies measuring urinary NGAL.

Acute kidney injury (AKI) represents a medical emergency associated with poor clinical outcomes. The international guideline group Kidney Disease: Improving Global Outcomes (KDIGO) has defined AKI according to rises in serum creatinine and/or reductions in urine output. Any patient who meets the criteria for AKI should be reviewed to ascertain the cause of AKI and the severity of the injury should be staged. Patients with more severe AKI are at greater risk of progression to chronic kidney disease (CKD). The 2009 National Confidential Enquiry into Patient Outcomes and Death (NCEPOD) reported that only 50% of patients who died with a diagnosis with AKI received good care. The mortality from AKI has remained unchanged for the last four decades and there are currently no specific therapies for the majority of cases of AKI. Patients with rarer forms of AKI need urgent renal referral for specific therapy. At present, serum creatinine and urine output remain the best biomarkers for detecting AKI. However, significant kidney damage has usually occurred by the time changes in these biomarkers are manifest and newer biomarkers are under investigation. Management of AKI is based upon general supportive measures, which includes treatment of the underlying cause and the initiation of renal replacement therapy (RRT) in patients with complications refractory to medical management. The optimal choice of intravenous fluid therapy remains controversial. There is currently renewed interest in more specific therapies for AKI secondary to hypoperfusion and/or sepsis, which have been previously unsuccessful. A number of therapeutic strategies are presently being explored in clinical trials.

We report a case of Influenza A-induced rhabdomyolysis causing acute kidney injury in a young adult female who required invasive ventilation and renal replacement therapy. This case was further complicated by posterior reversible encephalopathy syndrome. Although this represents an extremely rare neurological complication of Influenza A infection, an appreciation of the condition and its management is important, given the high numbers of critically ill patients recently affected by H1N1 Influenza A in intensive care units in the UK., (© 2011 The Authors. Anaesthesia © 2011 The Association of Anaesthetists of Great Britain and Ireland.)

Immunodepletion of clinical fluids to overcome the dominance by a few very abundant proteins has been explored but studies are few, commonly examining only limited aspects with one analytical platform. We have systematically compared immunodepletion of 6, 14, or 20 proteins using serum from renal transplant patients, analysing reproducibility, depth of coverage, efficiency, and specificity using 2-D DIGE ('top-down') and LC-MS/MS ('bottom-up'). A progressive increase in protein number (≥2 unique peptides) was found from 159 in unfractionated serum to 301 following 20 protein depletion using a relatively high-throughput 1-D-LC-MS/MS approach, including known biomarkers and moderate-lower abundance proteins such as NGAL and cytokine/growth factor receptors. On the contrary, readout by 2-D DIGE demonstrated good reproducibility of immunodepletion, but additional proteins seen tended to be isoforms of existing proteins. Depletion of 14 or 20 proteins followed by LC-MS/MS showed excellent reproducibility of proteins detected and a significant overlap between columns. Using label-free analysis, greater run-to-run variability was seen with the Prot20 column compared with the MARS14 column (median %CVs of 30.9 versus 18.2%, respectively) and a corresponding wider precision profile for the Prot20. These results illustrate the potential of immunodepletion followed by 1-D nano-LC-LTQ Orbitrap Velos analysis in a moderate through-put biomarker discovery process., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

There is a paucity of outcome data for critically ill patients with combined acute liver and kidney injury secondary to paracetamol overdose (POD) requiring renal replacement therapy (RRT). We retrospectively reviewed all admissions over a 6-year period to the intensive care unit (ICU) at a university teaching hospital which supports an active liver transplant program. Of the 5582 admissions over this period, 73 patients were admitted with combined liver and kidney injury requiring RRT, and of these 10 patients went on to receive a liver transplant. Overall mortality was 58%, being lower at 20% for transplant recipients. Transplant recipients were younger than non-transplanted patients with similar global disease severity scores [Model for End-Stage Liver Disease (MELD) and Acute Physiology and Chronic Health Evaluation II (APACHE II)]. Patients with a higher MELD or APACHE II score fared worse and patients fulfilling the King's College Hospital transplant criteria on admission had an odds ratio (OR) for death of 3.8 (1.3-10.6). Logistic regression modeling found that only a higher admission bilirubin OR 1.6 (1.1-2.3) mg/dL and a lower creatinine OR 0.52 (0.3-0.9) mg/dL were predictive of mortality. Of the ICU survivors, 41% remained RRT dependant at the time of ICU discharge; all regained independent renal function by 1 month. Combined severe acute liver and kidney injury secondary to POD requiring RRT is associated with a high mortality. The majority of survivors recover independent kidney function by 1 month. Standard disease severity scores appear to reflect prognosis in these patients.

There has been increased interest in acute kidney injury (AKI) over the past decade following the recognition of the association of relatively small rises in serum creatinine with worse patient outcomes. This association has resulted in newly proposed definitions in AKI based on changes in serum creatinine. In 2009, the National Confidential Enquiry into Patient Outcomes and Death Adding Insult to Injury AKI study reported that only 50% of patients who died with a diagnosis of AKI received good care. The study identified multiple deficiencies and made a number of recommendations which included improving the training of undergraduate and postgraduate trainees in the management of AKI. The aim of the evaluation was to try and identify the perception of medical trainees in Leeds Teaching Hospitals of the training they had received on AKI. A simple questionnaire was used and captured the views of 73 trainees (including 13 final-year medical students). The evaluation indicated that the majority of trainees were unaware of newly proposed definitions of AKI, and many trainees felt that the training they had received in AKI was inadequate for their needs. Following this evaluation, we have made a number of changes to the training that is delivered to both undergraduate and postgraduate trainees in Leeds on the management of AKI.

Organ donation after cardiac death (DCD) provides a valuable supply of grafts for renal transplantation. Age matching of donors to recipients is often used. We sought to determine the impact of age matching on the outcomes among our cohort of DCD renal transplant recipients. Using our institutional database, we gathered information on all DCD renal transplants performed between April 2002 and December 2009. We divided the cohort into two groups based upon the donor:recipient age ratio: age-matched (between 25th and 75th percentiles, n = 99) and non-age-matched (<25th percentile and >75th centile, n = 100). We failed to demonstrate any significant difference between the two groups in terms of early complications or long-term outcome or function. Age matching did not appear to affect graft outcomes, particularly for young donors, but may have a role in older donors., (Copyright © 2010 Elsevier Inc. All rights reserved.)

With the increase of donation after cardiac death (DCD) now including procurements for not only kidney but also liver, pancreas, and lung transplantations, we analyze whether multiorgan DCD retrievals have a negative impact on immediate and short-term renal transplant outcomes due to increased length of time of explantation of the kidney from the donor and the associated risks of re-warming. We performed a retrospective study of all DCD donors from 2002 to 2009 at a single unit. Immediate and short-term outcomes between kidney-only versus multiorgan retrieval were compared. Cold ischaemia was significant between the two groups (P = .04), but all other variables were nonsignificant. The results show that immediate graft function, rates of acute rejection and graft/recipient survival are comparable when DCD allografts are procured from both multiorgan and kidney-only donors. The comparable outcomes from kidney-only and multiorgan donations in this study may be due to by the highly selective use of donors for multiorgan DCD donation. This selectivity may explain the "better" quality of kidney for these cases in which patients were able to tolerate potentially injurious rewarming., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Background: Late-onset proteinuria after renal transplantation has been universally associated with poor allograft outcomes. However, the significance of early low-grade posttransplant proteinuria remains uncertain., Methods: We analyzed the effect of proteinuria 3 months posttransplantation on death-censored graft loss, death with a functioning graft, vascular events within the graft's life, and estimated glomerular filtration rate at 5 years. Four hundred seventy-seven renal transplants from a single center (1988-2003) with a mean follow-up of 122 months were divided into four groups based on the median protein creatinine ratio (PCR) during the 3rd posttransplant month (PCR<0.15 [group 1, n=85]; PCR 0.15-0.5 [group 2, n=245]; PCR 0.5-1.00 [group 3, n=96]; PCR>1.00 [group 4, n=51]). Cox proportional hazards analysis was performed to study the impact of proteinuria on the various outcomes., Results: Multivariate analysis revealed that even low-level proteinuria at 3 months predicted death-censored graft failure (group 1 [reference]--hazard ratio [HR]=1, group 2--HR=7.1, group 3--HR = 10.5, group 4--HR 16.0; P=0.001). The impact on death and the occurrence of vascular events was only significant for group 4 (HR: 2.6; P=0.01 for death and HR: 2.2; P=0.04 for vascular events). Estimated glomerular filtration rate at 5 years was group 1, 48.5 mL/min; group 2, 41.2 mL/min; group 3, 31.1 mL/min; and group 4, 24.5 mL/min (P<0.001). Continued observation of group 2 to 1 year revealed adverse outcomes with increasing proteinuria., Conclusions: Low-grade proteinuria at 3 months is associated with adverse clinical outcomes and identifies high-risk group of patients who may benefit from further intervention.

Over recent years, there has been welcome increased interest in acute kidney injury (AKI) and its association with patient outcome. The term AKI has replaced the term acute renal failure (ARF) and encompasses all types of ARF. New definitions and staging systems for AKI have been proposed, which have stimulated a multitude of different studies to evaluate their clinical utility. These recent advances need to be communicated to the wider health care community so that we are using a shared nomenclature. In 2009 the National Confidential Enquiry into Patient Outcome and Death AKI study ('Adding Insult to Injury') announced its findings and recommendations. The report recommended that the detection of AKI and its management should be improved. These recommendations along with the adoption of the new staging systems will potentially have an impact on clinical biochemistry departments and exert an increased demand on resources. Running in parallel with these initiatives is the quest to discover novel biomarkers to detect AKI, the development and introduction of which will require laboratory support.

Proteomics-based approaches are generating considerable data in clinical nephrology covering almost all aspects of the discipline. Proteomic experiments commonly involve fractionation and protein separation, followed by mass spectrometric analysis to identify proteins and peptides. Biostatistical and bioinformatical input is essential in such experiments, from initial experimental design to analysis of data. Standardization of procedures is an important research objective. Depending on study design, results can lead to biomarker discovery, mechanistic insight and identification of potential avenues for therapeutic intervention and treatment evaluation. Understanding proteomic information and its place in current clinical research and practice is fundamental. This Review describes proteomic experimentation and the concepts behind it, and gives an overview of its application to important areas in clinical nephrology including acute kidney injury, chronic kidney disease, end-stage renal disease, genetic diseases and fluid and electrolyte disorders, with a particular focus on biomarker discovery. The importance of future developments, such as the establishment of an infrastructure for a 'biomarker pipeline' with structured validation pathways for candidate biomarkers and development of clinical assays, is also discussed and some future perspectives are presented.

Use of depopulated bovine ureteric xenografts for hemodialysis vascular access has recently been described. Cellular components have been removed, giving a connective tissue matrix which can be neocellularized, retaining native biomechanics. A 24-year-old male with end-stage renal disease from focal segmental glomerulosclerosis presented with particularly difficult vascular access. A depopulated bovine ureteric xenograft was implanted from the left subclavian artery to innominate vein. It became massively aneurysmal, requiring emergency embolization. Biopsy of the graft stained positive for alpha-gal. We believe this is the first reported case of massive aneurysmal dilatation of a depopulated bovine ureteric xenograft.

Vascular disease and chronic allograft nephropathy have prompted re-evaluation of steroids and calcineurin inhibitors (CNIs) in renal transplantation. Sirolimus (SRL) can facilitate early CNI withdrawal. We report on the Early CNI and Steroid Elimination in Leeds (ECSEL) study, which was terminated early due to poor tolerability of SRL. Basiliximab/methylprednisolone induction was used, then 2 months of tacrolimus (TAC) and mycophenolate mofetil (MMF) treatment. A total of 51 patients were randomized to continue TAC/MMF or switch to SRL/MMF. In ECSEL1, patients were switched at 2 months (n=10). In ECSEL2, SRL was introduced at months 4-6 and TAC was tapered (n=13). Median overall follow up was 701 days. All 10 ECSEL1 and 10 of 13 (77%) ECSEL2 patients discontinued SRL due to adverse events, including leucopenia, rash, mucosal ulceration, arthralgia, and possible pneumonitis. Mean end-of-study creatinine was comparable in all groups. Sirolimus should be used with caution in complete CNI and steroid withdrawal, due to the resultant intolerable adverse event profile.

Aims/hypothesis: Proinsulin C-peptide is generally believed to be inert without any appreciable biological functions. However, it has been shown to modulate a variety of cellular processes important in the pathophysiology of diabetic complications. We therefore investigated the ability of C-peptide to stimulate intracellular signalling pathways in kidney proximal tubular cells, the altered activation of which may possibly be related to the development of diabetic nephropathy., Methods: Extracellular signal-regulated kinase (ERK) and Akt phosphorylation were evaluated by western blotting. ERK activity was measured by in vitro kinase assay. Intracellular Ca(2+) was evaluated by confocal imaging. The membrane and cytosol-associated fractions of protein kinase C (PKC) isoforms were evaluated by western blotting. Proliferation was assessed by thymidine incorporation assay., Results: Using the opossum proximal tubular kidney cell line as a model, we demonstrated that at high picomolar to low nanomolar concentrations, C-peptide stimulates extracellular signal-regulated mitogen-activated kinase (3.3+/-0.1-fold over basal at 3 minutes) and phosphatidylinositol 3-kinase (4.1+/-0.05-fold over basal at 5 minutes). ERK activation was attenuated by pre-treatment with a PKC inhibitor and abolished by pertussis toxin. Elevations of intracellular [Ca(2+)] are seen in response to 5 nmol/l C-peptide with consequent activation of PKC-alpha. Pre-treatment with pertussis toxin abolished PKC-alpha. C-peptide is also a functional mitogen in this cell type, stimulating significantly increased cell proliferation. Proliferation was attenuated by wortmannin and pertussis toxin pre-treatments. None of these effects is reproduced by scrambled C-peptide., Conclusions/interpretation: This study provides evidence that C-peptide, within physiological concentration ranges, stimulates many signalling pathways in opossum kidney cells.

Unlabelled: Background. Peroxisome proliferator activated receptors (PPARs) are ligand-activated transcription factors with multiple effects on target cell function. PPAR gamma activity is regulated by extracellular signal-regulated protein kinase (ERK), mitogen-activated protein (MAP) kinase, and PPAR gamma ligands have varying effects on activity of ERK. Different PPAR gamma ligands have been shown to have both protective and detrimental effects in the kidney. Since transcriptional activation by different PPAR agonists is ligand- and depot-specific PPAR gamma, we have examined the effects of different agonists on PPAR activity in the proximal tubule., Methods: Opossum kidney cells were used in all experiments, transiently transfected with a PPAR response element luciferase reporter and subject to stimulation with various PPAR ligands. The role of ERK and phosphorylation in PPAR gamma activation were studied, as were the effects of PPAR agonists on ERK activation and cell proliferation., Results: Transcriptional activity of PPAR was not stimulated by PPAR alpha agonists, and only very modestly stimulated by a PPAR beta agonist. The PPAR gamma agonists 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), ciglitazone, and troglitazone stimulated significant transcriptional activation and phosphorylation of PPAR gamma. These effects were more marked with 15d-PGJ(2). Thiazolidinediones attenuated 15d-PGJ(2) evoked PPAR gamma activation and phosphorylation. ERK activity positively regulated PPAR activation. Only 15d-PGJ(2) stimulated ERK activity and cell proliferation, and these effects were also inhibited by thiazolidinediones., Conclusion: PPAR gamma agonists exert differential effects in proximal tubule cells with thiazolidinediones behaving as partial agonists.

The enzyme, poly(ADP-ribose) polymerase (PARP), effects repair of DNA after ischemia-reperfusion (I/R) injury to cells in nerve and muscle tissue. However, its activation in severely damaged cells can lead to ATP depletion and death. We show that PARP expression is enhanced in damaged renal proximal tubules beginning at 6-12 h after I/R injury. Intraperitoneal administration of PARP inhibitors, benzamide or 3-amino benzamide, after I/R injury accelerates the recovery of normal renal function, as assessed by monitoring the levels of plasma creatinine and blood urea nitrogen during 6 days postischemia. PARP inhibition leads to increased cell proliferation at 1 day postinjury as assessed by proliferating cell nuclear antigen and improves the histopathological appearance of kidneys examined at 7 days postinjury. Furthermore, inhibition of PARP increases levels of ATP measured at 24 h postischemia compared with those in vehicle-treated animals. Our data indicate that PARP activation is a part of the cascade of molecular events that occurs after I/R injury in the kidney. Although caution is advised, transient inhibition of PARP postischemia may constitute a novel therapy for acute renal failure.

De novo CD44 and ligand expression at wound margins accompanies cellular proliferation and migration that effect repair of injured mucosal and vascular endothelial tissues. To determine whether CD44 could play a role in recovery from acute ischemic renal injury, we characterized its renal expression and those of two of its ligands, hyaluronic acid and osteopontin. Although no expression is detectable in nonischemic kidneys, several mRNAs for CD44 are present within 1 day after injury. CD44 mRNA is expressed in proximal tubules undergoing repair. CD44 peptide is present in basal and lateral cell membranes. Hyaluronic acid is normally expressed in the interstitium of the renal papilla only. By 1 day postischemia, hyaluronic acid can be detected, in addition, in the interstitium surrounding regenerating tubules. Osteopontin, not normally expressed in the renal proximal tubule, is expressed in regenerating tubules by 3 days after induction of acute ischemic injury. Immunoreactive osteopontin peptide continues to be localized in those tubules still undergoing repair for as long as 7 days after the injury. Our data are consistent with a role for CD44-ligand interactions in the regenerating proximal tubule participating in the process of recovery after ischemic injury.

Acute renal failure continues to have an unacceptably high mortality rate. Ischemic renal injury is the most common cause of acute renal failure. Understanding the molecular mechanisms of cell death and regeneration is important for designing future therapeutic strategies. Recent interest in our laboratory has focused on molecular response after ischemic renal injury and, in particular, genes that are important in cell death and repair after ischemia. The identification of genes that are differentially expressed after ischemia has led to new information regarding the identity of possible mediators of cell death and regeneration in renal tubular epithelial cells.

Background: Studies identifying genes that are differentially expressed following induction of acute ischemic injury have been useful in delineating the pathophysiology of acute renal failure., Methods: A differential cDNA library screening technique was used to identify genes that are differentially expressed in rat kidney following induction of acute ischemic renal injury., Results: Levels of mRNA with a high homology to that coding for Siva, a human proapoptotic protein, were increased approximately 4.5-fold in kidneys obtained from rats within 12 hours following ischemia, compared to kidneys from sham-operated rats. A partial cDNA sequence for the rat protein (rat Siva) was determined that overlaps 92% of the human open reading frame. The cDNA sequence predicts a protein 177 amino acids in length with 76% homology to human Siva. Levels of rat Siva in kidneys were elevated at one, five and seven days post-ischemia were not different from those in kidneys from sham-operated controls. In situ hybridization demonstrated that rat Siva mRNA was expressed in cells lining damaged sections in the S3 segment of the proximal tubule at 12 hours and one day post-ischemia. At five and seven days, Siva mRNA was located in epithelial cells of regenerating tubules including in papillary proliferations. TdT-mediated dUTP-biotin nick end-labeling (TUNEL)-positive cells colocalized with cells containing Siva mRNA. CD27, the receptor for Siva was localized by immunohistochemistry to sloughed cells in the lumens of damaged S3 segments at 12 hours post-ischemia and to cells within papillary proliferations at five days post-injury., Conclusions: Siva that is produced within the kidney could be a mediator of apoptosis post-ischemia via an interaction with CD27.

Genes differentially expressed after acute renal ischemic injury were identified using differential display-polymerase chain reaction (DD-PCR). Messenger RNA for calcyclin, a member of the S100 family of calcium-binding proteins, is increased in kidneys by 6 h following ischemic injury to rats compared with sham surgery. The level of calcyclin mRNA is increased 10-fold by 1 day postinjury and declines thereafter. In situ hybridization demonstrates little calcyclin mRNA in kidneys of sham-operated rats. However, calcyclin protein is present in glomeruli and distal tubules (DT). Compared with kidneys from sham-operated controls, both calcyclin mRNA and protein expression are increased at 1-3 days following ischemic injury in the thick ascending limb of Henle, the DT, and in damaged regenerating segments of proximal tubules. By 7 days postischemia there is a reduction in mRNA and protein expression. Calcyclin could play a role in the regulation of renal cell proliferation and regeneration in the recovery process after acute ischemic injury.