Renal failure secondary to acute tubular necrosis: epidemiology, diagnosis, and management

Potential therapeutic applications of circular RNA in acute kidney injury

Acute kidney injury (AKI) is a common clinical syndrome characterized by a rapid deterioration in renal function, manifested by a significant increase in creatinine and a sharp decrease in urine output. The incidence of morbidity and mortality associated with AKI is on the rise, with most patients progressing to chronic kidney disease or end-stage renal disease. Treatment options for patients with AKI remain limited. Circular RNA (circRNA) is a wide and diverse class of non-coding RNAs that are present in a variety of organisms and are involved in gene expression regulation. Studies have shown that circRNA acts as a competing RNA, is involved in disease occurrence and development, and has potential as a disease diagnostic and prognostic marker. CircRNA is involved in the regulation of important biological processes, including apoptosis, oxidative stress, and inflammation. This study reviews the current status and progress of circRNA research in the context of AKI.

Anti-inflammatory effect and mechanism of catalpol in various inflammatory diseases

Catalpol is a kind of iridoid glucoside, widely found in a variety of plants, mostly extracted from the rhizome of the traditional medicinal herb rehmanniae. It has various biological activities such as anti-inflammatory, antioxidant, and antitumor. The anti-inflammatory effects of catalpol have been demonstrated in a variety of diseases, such as neurological diseases, atherosclerosis, renal diseases, respiratory diseases, digestive diseases, bone and joint diseases, eye diseases, and periodontitis. The purpose of this review is to summarize the existing literature on the anti-inflammatory effects of catalpol in a variety of inflammatory diseases over the last decade and to focus on the anti-inflammatory mechanisms of catalpol.

N6-methyladenine RNA Methylation Epigenetic Modification and Kidney Diseases

RNA methylation modification is a rapidly developing field in epigenetics. N6-methyladensine (m⁶A) is the most common internal modification in eukaryotic mRNA. m⁶A group regulates RNA splicing, stability, translocation, and translation. Enzymes catalyzing this process were termed as writers, erasers, and readers. Recent studies have focused on exploring the role of RNA methylation in human diseases. RNA methylation modifications, particularly m⁶A, play important roles in the pathogenesis of kidney diseases. In this review, we provide a brief description of m⁶A and summarize the impact of m⁶A on acute and chronic kidney disease (CKD) and possible future study directions for this research.

Acute rhabdomyolysis in hepatitis-associated aplastic anemia patient undergoing allogeneic hematopoietic stem-cell transplantation: case report and literature review

Background

Hepatitis-associated aplastic anemia (HAAA) is a specific type of aplastic anemia, and hematopoietic stem-cell transplantation (HSCT) is recommended as the first-line. Acute rhabdomyolysis (AR) during hematopoietic stem-cell transplantation (HSCT) is a rare, serious complication, with only 10 cases reported in the world so far.

Case presentation

Herein, we present a case of AR developing during HLA-haploidentical HSCT in a 55-year-old man who suffered from HAAA. On day 7 after stem cell transfusion, the patient reported a muscle pull in thigh and complained of muscle swelling, pain and change in urine color. Despite the timely diagnosis (based on the levels of myoglobin and creatine kinase, and muscle MRI findings, etc.) and rapid hydration and alkalization, the situation progressed dramatically, and the patient died of multi-organ failure during the preparation for continuous renal replacement therapy (CRRT). Five days after his death, the whole-exome sequencing result confirmed that the patient had a germline missense mutation in SCN4A I 1545 V and ACTN3 R577X.

Conclusion

AR is a rare but threatening complication during HSCT, especially in cases with kidney dysfunction. The creatine kinase level may not truly and completely reflect the severity and prognosis for cases with localized lesion. We suggest that genetic analysis should be performed for better understanding the pathological changes of AR during HSCT, especially for patients with bone marrow failure.

miR-25-3p protects renal tubular epithelial cells from apoptosis induced by renal IRI by targeting DKK3

Renal ischemia-reperfusion injury (IRI) is one of the main causes of acute kidney injury (AKI). So far, there have been many studies on renal IRI, although an effective treatment method has not been developed. In recent years, growing evidence has shown that small noncoding RNAs play an important regulatory role in renal IRI. This article aims to explore whether microRNA-25-3p (miR-25-3p) plays a role in the molecular mechanism of renal IRI. The results showed that the expression level of miR-25-3p was significantly downregulated in a rat renal IRI model, and this result was confirmed with in vitro experiments. After the hypoxia-reoxygenation treatment, the apoptosis level of NRK-52E cells transfected with miR-25-3p mimics decreased significantly, and this antiapoptotic effect was antagonized by miR-25-3p inhibitors. In addition, we confirmed that DKK3 is a target of miR-25-3p. miR-25-3p exerts its protective effect against apoptosis on NRK-52E cells by inhibiting the expression of DKK3, and downregulating the expression level of miR-25-3p could disrupt this protective effect. In addition, we reconfirmed the role of miR-25-3p in rats. Therefore, we confirmed that miR-25-3p may target DKK3 to reduce renal cell damage caused by hypoxia and that miR-25-3p may be a new potential treatment for renal IRI.

LncRNA TUG1 attenuates ischaemia-reperfusion-induced apoptosis of renal tubular epithelial cells by sponging miR-144-3p via targeting Nrf2

Renal ischaemia/reperfusion (I/R) injury may induce kidney damage and dysfunction, in which oxidative stress and apoptosis play important roles. Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) are reported to be closely related to renal I/R, but the specific molecular mechanism is still unclear. The purpose of this research was to explore the regulatory effect of lncRNA TUG1 on oxidative stress and apoptosis in renal I/R injury. This research revealed that in renal I/R injury and hypoxia/reperfusion (H/R) injury in vitro, the expression level of lncRNA TUG1 was upregulated, and oxidative stress levels and apoptosis levels were negatively correlated with the expression level of lncRNA TUG1. Using bioinformatics databases such as TargetScan and microRNA.org, microRNA-144-3p (miR-144-3p) was predicted to be involved in the association between lncRNA TUG1 and Nrf2. This study confirmed that the level of miR-144-3p was significantly reduced following renal I/R injury and H/R injury in vitro, and miR-144-3p was determined to target Nrf2 and inhibit its expression. In addition, lncRNA TUG1 can reduce the inhibitory effect of miR-144-3p on Nrf2 by sponging miR-144-3p. In summary, our research shows that lncRNA TUG1 regulates oxidative stress and apoptosis during renal I/R injury through the miR-144-3p/Nrf2 axis, which may be a new treatment target for renal I/R injury.

Identification of MicroRNA-92a-3p as an Essential Regulator of Tubular Epithelial Cell Pyroptosis by Targeting Nrf1 via HO-1

Renal ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury (AKI) and has no effective treatment. Exploring the molecular mechanisms of renal IRI is critical for the prevention of AKI and its evolution to chronic kidney disease and end-stage renal disease. The aim of the present study was to determine the biological function and molecular mechanism of action of miR-92a-3p in tubular epithelial cell (TEC) pyroptosis. We investigated the relationship between nuclear factor-erythroid 2-related factor 1 (Nrf1) and TEC pyroptosis induced by ischemia-reperfusion in vivo and oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro. MicroRNAs (miRNAs) are regulators of gene expression and play a role in the progression of renal IRI. Nrf1 was confirmed as a potential target for miRNA miR-92a-3p. In addition, the inhibition of miR-92a-3p alleviated oxidative stress in vitro and decreased the expression levels of NLRP3, caspase-1, GSDMD-N, IL-1β, and IL-18 in vitro and in vivo. Moreover, Zn-protoporphyrin-IX, an inhibitor of heme oxygenase-1, reduced the protective effect of Nrf1 overexpression on OGD/R-induced TEC oxidative stress and pyroptosis. The results of this study suggest that the inhibition of miR-92a-3p can alleviate TEC oxidative stress and pyroptosis by targeting Nrf1 in renal IRI.

circ-AKT3 aggravates renal ischaemia-reperfusion injury via regulating miR-144-5p /Wnt/β-catenin pathway and oxidative stress

Renal ischaemia‐reperfusion (RI/R) injury is one major pathological state of acute kidney injury (AKI) with a mortality rate ranking 50% to 80%. MiR‐144‐5p acts as a molecular trigger in various diseases. We presumed that miR‐144‐5p might be involved RI/R injury progression. We found that RI/R injury decreased miR‐144‐5p expression in rat models. MiR‐144‐5p downregulation promoted cell apoptosis rate and activated Wnt/β‐catenin signal in RI/R injury rats. By performing bioinformatic analysis, RIP, RNA pull‐down, luciferase reporter experiments, we found that circ‐AKT3 sponged to miR‐144‐5p and decreased its expression in RI/R injury rats. Moreover, we found that circ‐AKT3 promoted cell apoptosis rate and activated Wnt/β‐catenin signal, and miR‐144‐5p mimic reversed the promotive effect of circ‐AKT3 in rat models. We also found that circ‐AKT3 increased the oxidative stress level in rat models. In conclusion, our study suggests that the circAKT3 is involved RI/R injury progression through regulating miR‐144‐5p/Wnt/β‐catenin pathway and oxidative stress.

Tisp40 Induces Tubular Epithelial Cell GSDMD-Mediated Pyroptosis in Renal Ischemia-Reperfusion Injury via NF-κB Signaling

Renal ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury (AKI). As a transcription factor, the Transcript induced in spermiogenesis 40 (Tisp40) has been found to be involved in renal IRI. However, the role of Tisp40 in tubular epithelial cell (TEC) pyroptosis of renal IRI remains unknown. In this study, we investigated effects of Tisp40 on Gasdermin D (GSDMD)-mediated TEC pyroptosis in renal IRI and underlying molecular mechanisms in I/R-induced kidney by hematoxylin and eosin (HE) staining, Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay,immunohistochemistry (IHC), reverse transcription-quantitative PCR (RT-qPCR) and western blot analysis in vivo and oxygen-glucose deprivation/reoxygenation (OGD/R)-stimulated TCMK-1 cells by lactate dehydrogenase (LDH) release assay, CCK-8 assay,enzyme-linked immunosorbent assay (ELISA), flow cytometric analysis, immunofluorescence staining,RT-qPCRand western blot analysis in vitro. We found that the levels of Tisp40 and GSDMD-N expression increased gradually, and peaked at 30 min ischemia/24 h reperfusion in vivo and 24 h OGD/R/6 h reoxygenation in vitro, simultaneously, the levels of TEC pyroptosis and renal injury were correspondingly increased. The data of Pearson’s correlation analysis showed that the expression of Tisp40 and GSDMD-N was positively correlated. Furthermore, Tisp40 overexpression aggravated TEC pyroptosis rate and increased the expressions of related proteins, including GSDMD-N, NLRP3, caspase-1, IL-1β, and IL-18 in the OGD/R-stimulated TCMK-1 cell line, whereas the opposite occurred in cells treated with small interfeing RNA (siRNA) targeting Tisp40. Tisp40-deficient mice showed attenuated renal IRI and pyroptosis compared with wild-type mice. In addition, Tisp40 knockout remarkably decreased the levels of GSDMD-N, IL-1β, IL-18, NLRP3, and caspase-1 expression, and alleviated renal pyroptosis induced by I/R. Importantly, Tisp40 overexpression significantly increased TECs pyroptosis via p-p65 activation, however, the effects of Tisp40 overexpression were partially blocked by parthenolide (PTL). Collectively, our findings provide insight into the mechanism of how Tisp40 regulated GSDMD-mediated pyroptosis in renal IRI.

Urinary neutrophil gelatinase-associated lipocalin determines short-term mortality and type of acute kidney injury in cirrhosis

Background and Aim

Acute kidney injury increases mortality in cirrhotic patients by four fold. This study aimed to determine the usefulness of urinary neutrophil gelatinase-associated lipocalin (uNGAL) for differential diagnosis for acute kidney injury and for predicting short-term mortality in cirrhotic patients.

Methods

We enrolled 94 patients of decompensated cirrhosis. uNGAL was measured upon hospital admission in all patients. Patients with urinary tract infection and anuria were excluded. Patients were followed for 30 days or until death.

Results

Ten (9%) patients had normal kidney function, 9 (11.37%) stable chronic kidney disease, 32 (29.50%) prerenal azotemia, 33 (36.37%) hepatorenal syndrome (HRS), and 10 (13.64%) intrinsic acute kidney injury (iAKI). Prerenal azotemia had lower median uNGAL values compared to HRS and iAKI (95.50 vs 465.00 vs 1217.50, P < 0.001). uNGAL levels were significantly higher in patients who died within 30 days (717.17 ± 494.26 vs 331.65 ± 313.65 ng/mL, P -0.0017). On univariate analysis, serum creatinine (sCr), uNGAL, Model for End-Stage Liver Disease (MELD) score on admission, and length of stay were significant, and on multivariate analysis, uNGAL and hepatic encephalopathy (HE) were significant in predicting mortality.

Conclusions

uNGAL at baseline serves as an early marker in differentiating HRS, prerenal AKI, and iAKI in cirrhotic patients, where sCr values are not useful. Patients with higher uNGAL levels had higher transplant-free mortality at 30 days.

Clinical Significance of Urinary Neutrophil Gelatinase-associated Lipocalin Levels in Defining the Various Etiologies of Acute Kidney Injury in Liver Cirrhosis Patients

Background/Aims

A diagnosis of hepatorenal syndrome (HRS) is based on a differential evaluation of acute kidney injury (AKI), which may aggravate the clinical course. This study assessed the clinical significance of the urinary neutrophil gelatinase- associated lipocalin (u-NGAL) levels in a differential diagnosis of AKI in patients with liver cirrhosis (LC).

Methods

Patients with LC who developed AKI were enrolled prospectively. Clinically, patients with AKI were classified into prerenal azotemia (PRA), HRS, and acute tubular necrosis (ATN) groups.

Results

Fifty-five patients (male, 74.5%) with LC who exhibited AKI upon admission were enrolled; 28, 9, and 18 patients were included in the PRA, HRS, and ATN groups, respectively. The baseline model for end-stage liver disease (MELD) scores was similar in the subgroups. The median event creatinine level, measured at the time of the AKI diagnosis, was similar in the HRS and ATN subgroups. On the other hand, the median event u-NGAL level differed significantly between the three subgroups (PRA, HRS, and ATN: 37 vs. 134 vs. 2,625 ng/mL, p=0.003). In particular, the median u-NGAL level of the HRS group was clearly different from those of the PRA (p<0.001) and ATN (p<0.001) groups. Multivariable analysis revealed the natural logarithm of the u-NGAL level (hazard ratio [HR] 1.77, p=0.031) and the MELD score (HR 1.17, p=0.027) to be independent prognostic factors for in-hospital mortality in patients with LC and AKI.

Conclusions

The median u-NGAL level differentiated HRS from ATN and served as a clinical indicator of in-hospital mortality for patients with LC and AKI.

Significant Reduction of Murine Renal Ischemia-Reperfusion Cell Death Using the Immediate-Acting PrC-210 Reactive Oxygen Species Scavenger

Background.

Ischemia-reperfusion (IR) injury remains a significant problem for all solid organ transplants; thus, an important unmet need in transplantation is the prevention of IR injury. PrC-210 has demonstrated superior prevention of reactive oxygen species damage in several preclinical studies as a free radical scavenger. Here, we describe its profound efficacy in suppressing IR injury in a murine model of kidney IR injury.

Methods.

C57/B6 mice underwent laparotomy with the left renal pedicle occluded for 30 minutes to induce IR injury. Right nephrectomy was performed at the time of surgery. Mice received a single systemic dose of the PrC-210, PrC-211, or PrC-252 aminothiols 20 minutes before IR injury. Twenty-four hours following IR injury, blood and kidney tissue were collected for analysis. Kidney caspase-3 level (a marker of cell death), direct histological analysis of kidneys, and serum blood urea nitrogen (BUN) were measured in animals to assess reactive oxygen species scavenger protective efficacies.

Results.

A single systemic PrC-210 dose 20 minutes before IR injury resulted in significant reductions in (1) IR-induced kidney caspase level (P < 0.0001); caspase was reduced to levels not significantly different than control caspase levels seen in unperturbed kidneys, (2) IR-induced renal tubular injury scores (P < 0.0001); brush border loss and tubular dilation were markedly reduced, and (3) serum BUN compared with control IR injury kidneys (P < 0.0001). The ranked protective efficacies of PrC-210 > PrC-211 >> PrC-252 paralleled previous radioprotection studies of the molecules.

Conclusions.

A single PrC-210 dose, minutes before the IR insult, profoundly reduced caspase, renal tubular injury, and serum BUN in mice exposed to standard kidney IR injury. These findings support further development of the PrC-210 molecule to suppress or prevent IR injury in organ transplant and other IR injury settings.

Metabolitic profiling of amino acids in paraquat-induced acute kidney injury

BACKGROUND

The herbicide paraquat (1, 1'-dimethyl-4, 4'-bipyridylium dichloride; PQ) is a poison well-known to cause delayed mortality due to acute kidney injuries (AKI). This study examines the changes in serum amino acids (AAs) metabolite profiles as surrogate markers of renal cell metabolism and function after paraquat poisoning.

METHODS

To identify the metabolic profiling of free serum AAs and its metabolites, serum from 40 paraquat-poisoned patients with or without AKI is collected. LC-MS/GC-MS is performed to analyze AA molecules. A Cox proportional hazard model was used to assess for incidence of AKI. Receiver operating characteristic (ROC) curve is applied to evaluate AKI occurrence and prognosis.

RESULTS

A total of 102 serum AAs and its metabolites were identified. Compared with non-AKI patients, 37 varied significantly in AKI patients. The univariate Cox proportional hazard model analysis revealed that the estimated PQ amount, plasma PQ concentration, urine PQ concentration, APACHE, SOFA scores and 16 amino acids correlated with the incidence of AKI. Further analyses revealed that 3-methylglutarylcarnitine, 1-methylimidazoleacetate, and urea showed higher cumulative hazard ratios for the occurrence of AKI during follow-up (P < 0.05). The area under the curve (AUC) of 3-methylglutarylcarnitine, 1-methylimidazoleacetate and urea were 0.917, 0.857, 0.872, respectively.

CONCLUSION

3-methylglutarylcarnitine, 1-methylimidazoleacetate and urea were associated with AKI in patients with paraquat intoxication.

Assessment and prediction of acute kidney injury in patients with decompensated cirrhosis with serum cystatin C and urine N-acetyl-β-D-glucosaminidase

BACKGROUND AND AIM

For appropriate management of acute kidney injury (AKI) in cirrhotic patients, accurate differentiation of the types of AKI, prerenal azotemia (PRA), hepatorenal syndrome (HRS), and acute tubular necrosis (ATN) is very important. Urine N-acetyl-β-D-glucosaminidase (NAG) has been proposed as a good tubular injury marker in many studies, but its efficacy in cirrhosis is unclear. This study was performed to evaluate the usefulness of urine NAG in patients with decompensated cirrhosis.

METHODS

In 114 hospitalized patients with decompensated cirrhosis, we assessed serum creatinine, cystatin C, and urine NAG levels as markers for AKI differentiation and development and patient mortality.

RESULTS

Thirty patients diagnosed with AKI at baseline had significantly higher serum creatinine and cystatin C levels, urine NAG levels, and Child-Pugh scores than those without AKI. Only urine NAG levels were significantly higher in patients with ATN than those with PRA or HRS (116.1 ± 46.8 U/g vs 39.4 ± 20.2 or 54.0 ± 19.2 U/g urinary creatinine, all P < 0.05). During a median follow up of 6.1 months, AKI developed in 17 of 84 patients: PRA in nine, HRS in six, and ATN in three. Higher serum cystatin C and urine NAG levels were independent predictors of AKI development in patients with decompensated cirrhosis. Survival was significantly associated with low serum cystatin C and urine NAG levels.

CONCLUSION

Serum cystatin C and urine NAG levels are useful to differentiate types of AKI and are strong predictors for AKI development and mortality in patients with decompensated cirrhosis.

NMR-based urine metabolic profiling and immunohistochemistry analysis of nephron changes in a mouse model of hypoxia-induced acute kidney injury

Acute kidney injury can be caused by multiple factors, including sepsis, respiratory failure, heart failure, trauma, or nephrotoxic medications, among others. Here, a mouse model was used to investigate potential urinary metabolic biomarkers of hypoxia-induced AKI. Urine metabolic profiles of 48 Swiss Webster mice were assessed using nuclear magnetic resonance spectroscopy (NMR) for 7 days following 72 h exposure to a hypoxic 6.5% oxygen environment. Histological analyses indicated a lack of gross nephron structural changes in the aftermath of hypoxia. Immunohistochemical (IHC) analyses, however, indicated elevated expression of protein injury biomarkers in distal and proximal tubules but not glomeruli. Kidney injury molecule-1 levels peaked in distal tubules at 72 h and were still increasing in proximal tubules at 7 days posthypoxia, whereas cystatin C levels were elevated at 24 h but decreased thereafter, and were elevated and still increasing in proximal tubules at 7 days posthypoxia. Neutrophil gelatinase-associated lipocalin levels were modestly elevated from 24 h to 7 days posthypoxia. NMR-based metabolic profiling revealed that urine metabolites involved in energy metabolism and associated biosynthetic pathways were initially decreased at 24 h posthypoxia, consistent with metabolic suppression as a mechanism for cell survival, but were significantly elevated at 48 and 72 h posthypoxia, indicating a burst in organism metabolism associated with reactivation of cellular energetics during recovery after cessation of hypoxia and return to a normoxic environment. The IHC results indicated that kidney injury persists long after plasma and urine biomarkers of hypoxia return to normal values.

17β-Estradiol Accelerated Renal Tubule Regeneration in Male Rats After Ischemia/Reperfusion-Induced Acute Kidney Injury

Ischemic/reperfusion injury (IRI) is the most common cause of acute kidney injury (AKI). Murine studies report that pretreatment with 17β-estradiol protects against AKI using multiple mechanisms, but how 17β-estradiol is involved in regenerating tubular cells is unknown. To visualize the kidney injury and repair, we used 17β-estradiol to treat rats with postischemic acute kidney injury. AKI was induced by clamping the renal pedicle for 90 minutes 2 weeks after a unilateral nephrectomy. Rats were treated with an intravenous injection of 17β-estradiol or vehicle immediately after reperfusion. Kidney injury was assessed by measuring biochemical and histopathological changes. Immunohistochemical staining of vimentin, proliferating cell nuclear antigen (PCNA), and E-cadherin were used to assess dedifferentiation, proliferation, and redifferentiation. Rats treated with 17β-estradiol had less kidney injury than did vehicle-treated rats post-IRI day 1. The number of PCNA-positive (PCNA) cells was significantly higher in post-IRI kidneys on day 1 in 17β-estradiol-treated rats. Moreover, vimentin and E-cadherin cells, which were interpreted as regeneration markers, were expressed earlier and significantly more copiously in 17β-estradiol-treated rats. We hypothesize that 17β-estradiol attenuates IRI-induced AKI by reducing inflammation and accelerating injured tubular cell regeneration.

NMR spectroscopy and electron microscopy identification of metabolic and ultrastructural changes to the kidney following ischemia-reperfusion injury

Cellular, molecular, and ultrastructural nephron changes associated with ischemia-reperfusion injury-induced acute kidney injury (IRI-AKI) are not completely understood. Here, a multidisciplinary study was used to identify nephron changes in a mouse model of IRI-AKI. Histological analyses indicated distended Bowman's glomerular spaces and proximal and distal tubules. Increased filtrate volume in nephrons was caused by reduced water reabsorption by severely damaged proximal tubule brush borders and blocked flow of filtrate into collecting tubules by mucoprotein casts in distal tubules. Immunohistochemistry revealed protein AKI biomarkers in proximal tubules and glomeruli but not in distal tubules. Nuclear magnetic resonance spectroscopy revealed several metabolites that increased such as valine, alanine, and lactate. Other metabolites such as trigonelline, succinate, 2-oxoisocaproate, and 1- methyl-nicotinamide decreased or were absent in urine following IRI due to altered kidney function or metabolism. Urinary glucose increased due to reduced reabsorption by damaged proximal tubule brush borders. Scanning electron microscopy revealed flattening of podocytes and pedicals surrounding glomerular capillaries, and transmission electron microscopy (TEM) revealed effacement of podocyte pedicals, both consistent with increased hydrostatic pressure in nephrons following IRI-AKI. TEM revealed shortened proximal tubule microvilli in IRI kidneys with diminished lamina propia. TEM showed dramatic loss of mitochondria in distal tubule epithelia of IRI kidneys and emergence of multivesicular bodies of endosomes indicating ongoing cellular death. Collectively, the data define ultrastructural changes to nephrons and altered kidney metabolism associated with IRI-AKI.

Nephroprotective Effect of EDL Peptide at Acute Injury of Kidneys of Different Genesis

EDL peptide produced a nephroprotective effect on experimental models gentamycin-induced nephropathy and ischemia/reperfusion kidney injury in rats. The nephroprotective effect of EDL peptide manifested in prevention of oliguria and retention azotemia, a decrease in proteinuria and sodium excretion, prevention of critical decrease in activities of antioxidant enzymes, suppression of LPO, and normalization of energy supply to kidneys cells. Our findings confirm the prospects of further studies of the nephroprotective properties of peptide EDL in various pathologies of the kidneys.

Depletion of Gut Microbiota Protects against Renal Ischemia-Reperfusion Injury

An accumulating body of evidence shows that gut microbiota fulfill an important role in health and disease by modulating local and systemic immunity. The importance of the microbiome in the development of kidney disease, however, is largely unknown. To study this concept, we depleted gut microbiota with broad-spectrum antibiotics and performed renal ischemia-reperfusion (I/R) injury in mice. Depletion of the microbiota significantly attenuated renal damage, dysfunction, and remote organ injury and maintained tubular integrity after renal I/R injury. Gut flora-depleted mice expressed lower levels of F4/80 and chemokine receptors CX3CR1 and CCR2 in the F4/80⁺ renal resident macrophage population and bone marrow (BM) monocytes than did control mice. Additionally, compared with control BM monocytes, BM monocytes from gut flora-depleted mice had decreased migratory capacity toward CX3CL1 and CCL2 ligands. To study whether these effects were driven by depletion of the microbiota, we performed fecal transplants in antibiotic-treated mice and found that transplant of fecal material from an untreated mouse abolished the protective effect of microbiota depletion upon renal I/R injury. In conclusion, we show that depletion of gut microbiota profoundly protects against renal I/R injury by reducing maturation status of F4/80⁺ renal resident macrophages and BM monocytes. Therefore, dampening the inflammatory response by targeting microbiota-derived mediators might be a promising therapy against I/R injury.

Activated protein C protects against renal ischaemia/reperfusion injury, independent of its anticoagulant properties

Acute renal failure, a serious condition characterised by a drastic decline in renal function, often follows ischaemia/reperfusion (I/R) episodes. I/R is characterised by necrosis, inflammation and activation of coagulation, in concert causing renal tissue damage. In this context, activated protein C (APC) might be of importance in the pathogenesis of renal I/R. APC is a serine protease which has anticoagulant but also several anti-inflammatory and cytoprotective effects such as protection of endothelial barrier function. It was our objective to study the role of cytoprotective and anticoagulant functions of APC during renal I/R. C57BL/6j mice subjected to renal I/R were treated with intraperitoneally injected exogenous human APC, or two mutant forms of APC (200 µg/kg) which specifically lack anticoagulant or signalling properties. In a different experiment mice received specific monoclonal antibodies (20 mg/kg) that block the cytoprotective and/or anticoagulant properties of endogenous APC. Treatment with APC reduced tubular injury and enhanced renal function without altering the inflammatory response and did reduce renal fibrin deposition. Administration of APC mutant lacking anticoagulant properties reduced renal damage and enhanced renal function. Blocking the anticoagulant and cytoprotective functions of endogenous APC resulted in elevated tubular damage and reduced tubular cell proliferation, however, without influencing renal function or the inflammatory response. Furthermore, blocking both the anticoagulant and cytoprotective effects of APC resulted in dramatic renal interstitial haemorrhage, indicative of impaired vascular integrity. Blocking only the anticoagulant function of APC did not result in interstitial bleeding. In conclusion, the renoprotective effect of APC during I/R is independent of its anticoagulant properties.

Study of the Effect of Route of Administration of Mesenchymal Stem Cells on Cisplatin-Induced Acute Kidney Injury in Sprague Dawley Rats

BACKGROUND AND OBJECTIVES

Mesenchymal stem cells (MSCs) have been shown to ameliorate cisplatin-induced acute kidney injury (AKI). The present study compares the efficacy of different routes of MSCs administration on kidney damage and regeneration after cisplatin-induced AKI.

METHODS

A single intraperitoneal injection of cisplatin (5 mg/kg) was used to induce AKI in 160 rats. MSCs (5×10⁶) were given by either intravenous, intra-arterial or kidney sub capsular injection one day after cisplatin injection. Suitable control groups were included. Rats were sacrificed at 4, 7, 11 and 30 days after cisplatin injection. Kidney function parameters, kidney tissue oxidative stress markers, and scoring for renal tissue injury, regeneration and chronicity were all determined.

RESULTS

MSCs by any routes were able to ameliorate kidney function deterioration and renal tissue damage induced by cisplatin. The overall results of the three routes were equal. Differences between the different routes in one parameter were transient and inconsistent with other parameters.

CONCLUSIONS

Changing the route of MSCs injection does not have a major influence on the outcome. Future evaluation should focus on differences between the routes of administration considering the long term safety.

Renal Ischemia/Reperfusion Injury in Diabetic Rats: The Role of Local Ischemic Preconditioning

Background. The aim of this study was to evaluate the effects of local ischemic preconditioning using biochemical markers and histopathologically in the diabetic rat renal IR injury model. Methods. DM was induced using streptozotocin. Rats were divided into four groups: Group I, nondiabetic sham group (n = 7), Group II, diabetic sham group (n = 6), Group III, diabetic IR group (diabetic IR group, n = 6), and Group IV, diabetic IR + local ischemic preconditioning group (diabetic IR + LIPC group, n = 6). Ischemic renal injury was induced by clamping the bilateral renal artery for 45 min. 4 h following ischemia, clearance protocols were applied to assess biochemical markers and histopathologically in rat kidneys. Results. The histomorphologic total cell injury scores of the nondiabetic sham group were significantly lower than diabetic sham, diabetic IR, and diabetic IR + LIPC groups. Diabetic IR group scores were not significantly different than the diabetic sham group. But diabetic IR + LIPC group scores were significantly higher than the diabetic sham and diabetic IR groups. Conclusion. Local ischemic preconditioning does not reduce the risk of renal injury induced by ischemia/reperfusion in diabetic rat model.

Urine neutrophil gelatinase-associated lipocalin: a diagnostic and prognostic marker for acute kidney injury (AKI) in hospitalized cirrhotic patients with AKI-prone conditions

BACKGROUND

Acute kidney injury (AKI) is known to increase mortality in hospitalized cirrhotic patients; therefore early identification is utmost significance. There are only a few studies evaluating the cut-off level of urine neutrophil gelatinase-associated lipocalin (uNGAL) for diagnosing AKI and its prognostic value in cirrhotic patients. We aimed to determine the accuracy of uNGAL as a biomarker for early identification of AKI and to determine the cut-off level of uNGAL for diagnosing AKI in hospitalized cirrhotic patients; and (2) to explore the association of 30-day liver-related mortality with uNGAL level.

METHODS AND MATERIAL

We prospectively enrolled cirrhotic patients admitted at the King Chulalongkorn Memorial Hospital during May 1, 2011 to Dec 31, 2013. UNGAL levels were measured within 24 h after admission. Clinical and laboratory data were obtained. Patients were followed up to 30 days.

RESULTS

Of 137 cirrhotic hospitalized patients, 121 cirrhotic patients (88.3 %) with AKI-prone conditions were included with mean age of 57.3 ± 14.7 years. Thirty-five patients (29 %) developed AKI within 72 h of admission. The causes of AKI were prerenal azotemia (68.6 %), acute tubular necrosis (25.7 %), hepatorenal syndrome (5.7 %), respectively. The mean uNGAL level was significantly higher in the patients who developed AKI compared with those who did not (290.6 ± 356.3 vs. 54.4 ± 73.7 ng/mL; P = 0.0001). The AUC of uNGAL for diagnosing AKI was 0.83 (95 % [CI]: 0.76-0.91) with the optimal cut-off level of 56 ng/mL, providing 77.1 % sensitivity and 73.3 % specificity. Fourteen percent of subjects died during the 30-day follow-up period. The mean uNGAL levels were significantly higher in the mortality group. The AUC of uNGAL in predicting mortality was 0.75 (95 % [CI]: 0.66-0.85), with a best cut-off level of 72 ng/mL providing 70.6 % sensitivity and 69.2 % specificity. However, in multivariate logistic regression analysis, uNGAL is not an independent factor for 30-day liver-related mortality prediction.

CONCLUSIONS

uNGAL is a valid marker for the early detection of AKI in hospitalized cirrhotic patients with AKI-prone conditions; however, its level could not independently predict 30-day liver-related mortality.

Chemotherapy-related complications in the kidneys and collecting system: an imaging perspective

Nephrotoxicity is a common adverse effect of many chemotherapeutic agents. The agents most commonly associated with chemotherapy-associated nephrotoxicity are methotrexate, semustine, streptozocin, mithramycin, and cisplatin. Certain chemotherapeutic agents have adverse effects on the kidneys and urothelium that can be visualized radiographically, including cystic change, interstitial nephritis, papillary necrosis, urothelial changes, haemorrhagic cystitis, acute tubular necrosis, and infarction. This review focuses on imaging features identifying complications of chemotherapy in the kidneys and collecting system and provides didactic cases to alert referring clinicians.

TEACHING POINTS

• Nephrotoxicity is a common adverse effect of many chemotherapeutic agents. • Chemotherapies have adverse renal and urothelial effects that can be visualized radiographically. • Crizotinib use can result in the development of complex renal cysts.

Postconditioning attenuates renal ischemia-reperfusion injury by mobilization of stem cells

BACKGROUND

We recently showed that reactive oxygen species (ROS) and mitochondrial DNA damage and deletions were attenuated by postconditioning (POC). It is not known, however, whether a population of progenitor cells is recruited by POC and is responsible for repair of renal tubular epithelial cells after ischemic injury.

METHODS

The model of renal POC was induced by 45 min clamping of the left renal artery and right nephrectomy followed by 7 min of short-time full reperfusion and 3 cycles of 30 s ischemia and 30 s reperfusion. The lymphocyte compartment of peripheral blood was evaluated by fluorescence-activated cell sorting (FACS) to determine expression of the bone marrow-derived progenitor cell markers CXC-chemokine receptor 4 (CXCR4), c-Kit, and CD34, at 12 h, 1 day and 3 days post-ischemia. Serum and kidney tissue were collected for analysis at 3 and 7 days post-ischemia.

RESULTS

Renal functional and structural recovery was markedly improved by POC, which increased the number of CXCR4(+) and CD34(+) stem cells in peripheral blood and kidney tissue. Inhibition of ROS burst by POC was likely associated with increased hypoxia-inducible factor-1 expression, which may further promote stromal cell-derived factor 1 (SDF-1) expression.

CONCLUSIONS

The mechanisms of stem cell recruitment to the injured foci mobilized by POC appear to be mediated by moderate oxidative stress, which may lead to increased SDF-1 expression.

Urinary biomarkers of acute kidney injury in patients with liver cirrhosis

Acute kidney injury (AKI) is a common complication in cirrhotic patients. Serum creatinine is a poor biomarker for detection of renal impairment in cirrhotic patients. This study aimed to evaluate urinary neutrophil gelatinase-associated lipocalin (NGAL) and urinary interleukin-18 (IL-18) as early biomarkers of acute kidney injury in cirrhotic patients. 160 patients with cirrhosis admitted to the Liver Units at Zagazig University Hospitals were classified into three groups: (I) nonascitic patients, (II) ascitic patients without renal impairment, and (III) ascitic patients with renal impairment. Patients with renal impairment were further divided into four subgroups: [A] prerenal azotemia, [B] chronic kidney disease (CKD), [C] hepatorenal syndrome (HRS), and [D] acute tubular necrosis (ATN). Significant elevation of both urinary NGAL and urinary IL-18 in cirrhotic patients with renal impairment especially in patients with ATN was observed. Urinary NGAL and urinary IL-18 have the ability to differentiate between AKI types in patients with cirrhosis. This could improve risk stratification for patients admitted to the hospital with cirrhosis, perhaps leading to early ICU admission, transplant evaluation, and prompt initiation of HRS therapy and early management of AKI.

An update on acute kidney injury after cardiac surgery

Renal dysfunction following cardiac surgery is well recognised and mainly is of ischaemic origin. The spectrum varies from subclinical injuryto established renal failure requiring renal replacement therapy. Depending on definitions, acute kidney injury (AKI) may occur in up to 30% of post cardiac surgery patients. A new grading system for renal dysfunction, based on three levels of plasma creatinine and urine output, as well as the use of biomarkers may help the early identification of patients at risk and thereby hopefully improve outcome. Despite therapeutic advances, the morbidity and mortality associated with AKI have not changed markedly in the last decade.

Urinary biomarkers of acute kidney injury in patients with liver cirrhosis

BACKGROUND AND AIM

Acute kidney injury is a common complication in cirrhotic patients. Serum creatinine is a poor biomarker for detection of renal impairment in cirrhotic patients. The aim of this study was to evaluate Urinary Neutrophils Gelatinase-Associated Lipocalin (NGAL) and Urinary interleukin-18 (IL-18) as early biomarkers of acute kidney injury in cirrhotic patients.

PATIENTS AND METHODS

160 cirrhotic patients was enrolled in this study divided into 3 main groups according to presence or absence of ascites and renal impairment.

RESULTS

Significant elevation of both Urinary NGAL and Urinary IL-18 in cirrhotic patients with renal impairment especially in patients with Acute tubular necrosis (ATN) was observed. AUROC was (0.909) with (sensitivity 95.5%, specificity 76.1) for Urinary NGAL and AUROC was (0.975), with (sensitivity 95.5%, specificity 91.3%) for Urinary IL-18.

CONCLUSION

Both Urinary NGAL and Urinary IL-18 can act as urinary biomarkers of acute kidney injury in cirrhotic patient.

Clinical spectrum of rhabdomyolysis presented to pediatric emergency department

BACKGROUND

Rhabdomyolysis is a potentially life-threatening syndrome that can develop from a variety of causes. The aim of the work is to analyze the clinical spectrum and to evaluate the prevalence of various etiologies in children, who present to the emergency department (ED) with rhabdomyolysis.

METHODS

During a 6-year study period, we retrospectively analyzed the medical charts of patients, aged 18 years or younger, with a definite diagnosis of rhabdomyolysis and serum creatinine phosphokinase (CK) levels greater than 1000IU/L. We analyzed the clinical spectrum and evaluated the potential risk factors of acute renal failure (ARF).

RESULTS

Thirty-seven patients (mean age = 10.2 ± 5.5 years), including 26 males and 11 females, were enrolled in the study. Two of the most common presented symptoms in these 37 patients were muscle pain and muscle weakness (83.8% and 73%, respectively). Dark urine was reported in only 5.4% of the patients. The leading cause of rhabdomyolysis in the 0- to 9-year age group was presumed infection, and the leading cause in the 10- to 18-year age group was trauma and exercise. The incidence of ARF associated with rhabdomyolysis was 8.1 % and no child needed for renal replacement therapy (RRT). We did not identify any reliable predictors of ARF or need for RRT.

CONCLUSIONS

The classic triad of symptoms of rhabdomyolysis includes myalgia, weakness and dark urine are not always presented in children. The cause of rhabdomyolysis in younger age is different from that of teenager group. However, the prognosis of rhabdomyolysis was good with appropriate management.

Practical considerations for the dosing and adjustment of continuous renal replacement therapy in the intensive care unit

Familiarity with the initiation, dosing, adjustment, and termination of continuous renal replacement therapy (CRRT) is a core skill for contemporary intensivists. Guidelines for how to administer CRRT in the intensive care unit are not well documented. The purpose of this review is to discuss the modalities, terminology, and components of CRRT, with an emphasis on the practical aspects of dosing, adjustments, and termination. Management of electrolyte and acid-base derangements commonly encountered with acute renal failure is emphasized. Knowledge regarding the practical aspects of managing CRRT in the intensive care unit is a prerequisite for achieving desired physiological end points.

[Acute renal failure and severe malaria in Congolese children living in Kinshasa, Democratic Republic of Congo]

BACKGROUND

Data on acute renal failure in complicated malaria in children in the Democratic Republic of Congo are sparse. The objective of this study was to document the profile of acute renal failure in severe malaria in admitted patients in pediatric hospitals from Kinshasa.

METHODS

A prospective cohort study was conducted from January 2008 to December 2008 in children admitted in emergency units of five hospitals in Kinshasa for severe malaria.

RESULTS

In our series, 378 children with severe malaria were included. There were 226 boys and 152 girls (sex ratio 1.49). One hundred and ninety four (194) of these patients were under 5 years old. Acute renal failure was observed in 89 children (23.6%) and 87 of them had blackwater fever (BWF). This form of severe malaria was predominant in children older than 5 years. Quinine was the commonest antimalarial drug involved in the genesis of BWF. Dialysis was indicated in 23 children (24.0%) and was effective (acute peritoneal dialysis) in 21 patients. The death rate in children with ARF was 12.6% (n=87). Recovery of renal function was obtained by conservative treatment in the remained group.

CONCLUSION

This study confirmed the emergence of BWF in seemed protected autochthon children older than 5 years. BWF remained the leading cause of acute renal failure in complicated malaria among Congolese children in Kinshasa.

Survival and distribution of injected haematopoietic stem cells in acute kidney injury

BACKGROUND

Endogenous bone marrow-derived cells are known to incorporate into renal epithelium at a low rate. Haematopoietic stem cells (HSCs) rather than mesenchymal stem cells (MSC) are responsible for this phenomenon. MSCs have the potential to ameliorate kidney function after acute kidney injury (AKI) without directly repopulating the tubules. However, little is known about the short-term effect of HSCs.

METHODS

In this article, we analysed the survival rate and organ distribution of isolated rat HSCs injected into the renal artery after ischaemic renal injury, using quantitative real-time PCR, as well as their impact on renal function and histomorphology.

RESULTS

Intra-arterially injected Lin(-)CD90(+) HSCs were detected in the kidney at significant amounts only within the first 24 h after injection and were virtually absent by Day 2. Compared with control animals, no differences were seen after HSC administration with respect to kidney function or histomorphologic changes of AKI. At Day 7 HSCs were again readily detectable in the kidney suggesting a redistribution of cells at later time points. Of note, HSCs did not seem to have an exclusive tropism for the injured kidney but were detectable in the lungs, liver, spleen, heart and brain at all time points.

CONCLUSIONS

Injected HSCs do not appear to significantly contribute to tubular repair or ameliorate renal damage in ischaemic AKI although they may show considerable engraftment in various organs. These data further challenge the concept that injection of HSCs may be used as a therapeutic approach in treating AKI.

Liraglutide-induced acute kidney injury

Published case reports have documented the relationship between exenatide use and acute kidney injury. However, to our knowledge, no cases of this adverse effect with liraglutide, another glucagon-like peptide-1 receptor agonist approved for the treatment of type 2 diabetes mellitus, have been reported. We describe a 53-year-old Caucasian woman who came to a community hospital with severe and progressively worsening gastrointestinal symptoms for several weeks, leading to dehydration and development of acute kidney injury. Laboratory results showed an increase in her serum creatinine concentration to 22.8 mg/dl and blood urea nitrogen to 150 mg/dl; she also had lost 8.9 kg in the previous month. One month earlier, the patient had begun liraglutide 1.8 mg/day subcutaneously for uncontrolled type 2 diabetes. Use of the Naranjo adverse drug reaction probability scale indicated a possible relationship (score of 3) between the patient's development of acute kidney injury and liraglutide. Renal biopsy and laboratory testing were helpful in ruling out other potential causes of renal failure and adverse drug reactions due to other drugs such as ciprofloxacin and quinapril. After the reports of the renal biopsy were obtained, liraglutide was determined to be a likely cause of acute tubular necrosis. The patient was successfully treated with discontinuation of liraglutide, volume repletion, and hemodialysis. To our knowledge, this is the first documented case of liraglutide-induced acute tubular necrosis. Clinicians should be aware of this possible complication and closely follow liraglutide's dosage titration recommendations in the package insert. Patients should also be educated about the need to report unusual or prolonged gastrointestinal symptoms.

U-curve association between timing of renal replacement therapy initiation and in-hospital mortality in postoperative acute kidney injury

Background

Postoperative acute kidney injury (AKI) is associated with poor outcomes in surgical patients. This study aims to evaluate whether the timing of renal replacement therapy (RRT) initiation affects the in-hospital mortality of patients with postoperative AKI.

Methodology

This multicenter retrospective observational study, which was conducted in the intensive care units (ICUs) in a tertiary hospital (National Taiwan University Hospital) and its branch hospitals in Taiwan between January, 2002, and April, 2009, included adult patients with postoperative AKI who underwent RRT for predefined indications. The demographic data, comorbid diseases, types of surgery and RRT, and the indications for RRT were documented. Patients were categorized according to the period of time between the ICU admission and RRT initiation as the early (EG, ≦1 day), intermediate (IG, 2–3 days), and late (LG, ≧4 days) groups. The in-hospital mortality rate censored at 180 day was defined as the endpoint.

Results

Six hundred forty-eight patients (418 men, mean age 63.0±15.9 years) were enrolled, and 379 patients (58.5%) died during the hospitalization. Both the estimated probability of death and the in-hospital mortality rates of the three groups represented U-curves. According to the Cox proportional hazard method, LG (hazard ratio, 1.527; 95% confidence interval, 1.152–2.024; P = 0.003, compared with IG group), age (1.014; 1.006–1.021), diabetes (1.279; 1.022–1.601; P = 0.031), cirrhosis (2.147; 1.421–3.242), extracorporeal membrane oxygenation support (1.811; 1.391–2.359), initial neurological dysfunction (1.448; 1.107–1.894; P = 0.007), pre-RRT mean arterial pressure (0.988; 0.981–0.995), inotropic equivalent (1.006; 1.001–1.012; P = 0.013), APACHE II scores (1.055; 1.037–1.073), and sepsis (1.939; 1.536–2.449) were independent predictors of the in-hospital mortality (All P<0.001 except otherwise stated).

Conclusions

The current study found a U-curve association between the timing of the RRT initiation after the ICU admission and patients’ in-hospital mortalities, and alerts physicians of certain factors affecting the outcome after the RRT initiation.

Urinary neutrophil gelatinase-associated lipocalin as biomarker in the differential diagnosis of impairment of kidney function in cirrhosis

BACKGROUND & AIMS

Impairment of kidney function is common in cirrhosis but differential diagnosis remains a challenge. We aimed at assessing the usefulness of neutrophil gelatinase-associated lipocalin (NGAL), a biomarker of tubular damage, in the differential diagnosis of impairment of kidney function in cirrhosis.

METHODS

Two-hundred and forty-one patients with cirrhosis, 72 without ascites, 85 with ascites, and 84 with impaired kidney function, were studied. Urinary levels of NGAL were measured by ELISA.

RESULTS

Patients with impaired kidney function had higher urinary NGAL levels compared to patients with and without ascites. Patients with urinary tract infection (n=25) had higher uNGAL values than non-infected patients. Patients with acute tubular necrosis (ATN) had uNGAL levels markedly higher (417μg/g creatinine (239-2242) median and IQ range) compared to those of patients with pre-renal azotemia due to volume depletion 30 (20-59), chronic kidney disease (CKD) 82 (34-152), and hepatorenal syndrome (HRS) 76 (43-263) μg/g creatinine (p<0.001 for all). Among HRS patients, the highest values were found in HRS-associated with infections, followed by classical (non-associated with active infections) type-1 and type-2 HRS (391 (72-523), 147 (83-263), and 43 (31-74) μg/g creatinine, respectively; p<0.001). Differences in uNGAL levels between classical type 1 HRS and ATN on the one hand and classical type 1 HRS and CKD and pre-renal azotemia on the other were statistically significant (p<0.05).

CONCLUSIONS

uNGAL levels may be useful in the differential diagnosis of impairment of kidney function in cirrhosis. Urinary tract infections should be ruled out because they may increase uNGAL excretion.

Safety and diagnostic yield of renal biopsy in the intensive care unit

PURPOSE

Renal biopsy (RB) is occasionally performed in critically ill patients. The safety and impact of RB in this setting have not been reported.

METHODS

A 10-year (2000-2009) retrospective multicentre study was conducted in ten French intensive care units (ICU) on patients who underwent RB during their management. Medical files were retrieved for data analysis.

RESULTS

Seventy-seven patients underwent an RB of which 68 (88 %) were on a native kidney and 9 (12 %) on a transplanted kidney. Percutaneous ultrasound-guided RB was used in most cases (87 %). Fifty-seven per cent of the patients were on mechanical ventilation at the time of RB. RB-related complications occurred in 17 (22 %) patients, two were graded as severe (requirement for kidney embolization, eventually successful). In 35 (51 %) non-transplanted patients, RB established a specific diagnosis other than acute tubular necrosis (ATN), which was diagnosed in only 18 % of patients. In the remaining patients, only non-specific lesions were observed. Therapeutic modifications followed RB in 14 (21 %) non-transplanted patients. Presence of signs of systemic disease involving the renal tract, occurrence of renal failure before hospital admission, and absence of any factor usually associated with ATN significantly predicted the presence of a specific diagnosis at RB other than ATN.

CONCLUSIONS

In this cohort, the contribution of RB to diagnosis and treatment was undeniable, but at the expense of frequent adverse events although most of them were not considered severe.

Therapeutic potential of 7,8-dimethoxycoumarin on cisplatin- and ischemia/reperfusion injury-induced acute renal failure in rats

This study was designed to investigate the role of 7,8-dimethoxycoumarin on cisplatin- and ischemia/reperfusion (I/R)-induced acute renal failure in rats. Acute renal failure was induced in rats by administration of a single dose of cisplatin (CP) (6 mg/kg, intraperitoneally on day 6) and occlusion of the left renal artery for 45 min (I) and opened for the next 24 h (R). The drug samples of 7,8-dimethoxycoumarin (DMC, 50, 75, and 100 mg/kg) and cyclosporin A (50 μM/kg) were administered orally for six consecutive days. Administration of a single dose of cisplatin and I/R event has significantly raised blood urea nitrogen and creatinine, N-acetyl beta-D: -glucosaminidase, and thiobarbituric acid reactive substances but decreased FrNa, creatinine clearance, reduced glutathione (GSH), mitochondrial cytochrome c oxidase, and adenosine triphosphate levels. Further, pretreatment of DMC (50, 75, and 100 mg/kg, p.o., for six consecutive days) has ameliorated the CP- and I/R-induced biochemical and histopathological changes in a dose-dependent manner. Furthermore, 75 and 100 mg/kg of 7,8-dimethoxycoumarin has shown to possess the significant renoprotective effect similar to that of the cyclosporin A-treated group which served as positive control. Based on the results of the present study, it has been concluded that 7,8-dimethoxycoumarin protects the kidney against the CP and I/R injury via antioxidant, anti-inflammatory, and inactivation of mitochondrial permeability transition pore opening.

A Potential Biomarker for Acute Kidney Injury in Preterm Infants from Metabolic Profiling

BACKGROUND

Currently used biomarkers for acute kidney injury (AKI), namely Ngal, SCr, and BUN, are inadequate for timely detection of AKI in preterm infants.

METHODS

Nuclear magnetic resonance (NMR) spectroscopy-based metabolic profiling was conducted on urines from 20 preterm infants to determine if novel metabolic biomarkers could be identified for early detection of AKI. Urines were collected from every patient each day for the first 14 days of life. NMR spectra were measured for all urines and metabolic profiling analysis conducted.

RESULTS

One metabolite, carnitine, increased significantly in urines of three extremely low birth weight (ELBW) infants starting on day five of life. The three affected infants either received prolonged antibiotic treatment, extended treatment with indomethacin, or both. One ELBW patient who received both treatments and reached the highest urinary carnitine level died on day 10 of life due to localized gut perforation complicated by suspected AKI.

CONCLUSIONS

It was concluded that carnitine increased in the three neonates in part due to antibiotic- and/or indomethacin-induced AKI. It is hypothesized that combined antibiotic and indomethacin treatment promoted AKI resulting in reduced proximal renal tubule reabsorption of carnitine and that β-lactam antibiotics blocked renal carnitine uptake by human organic cation transporter, hOCTN2.

HCaRG accelerates tubular repair after ischemic kidney injury

The repair of the kidney after ischemia/reperfusion injury involves proliferation of proximal tubular epithelial cells as well as cell migration and differentiation. Immediately after reperfusion, expression of hypertension-related calcium-regulated gene (HCaRG/COMMD5) decreases, but its expression increases even higher than baseline during repair. HCaRG inhibits proliferation and accelerates wound healing and differentiation in cultured cells, but whether HCaRG can stimulate renal repair after ischemia/reperfusion injury is unknown. Here, transgenic mice overexpressing human HCaRG survived longer and recovered renal function faster than littermate controls after ischemia/reperfusion (64% versus 25% survival at 7 days). Proliferation of proximal tubular epithelial cells stopped earlier after ischemia/reperfusion injury, E-cadherin levels recovered more rapidly, and vimentin induction abated faster in transgenic mice. HCaRG overexpression also reduced macrophage infiltration and inflammation after injury. Taken together, these data suggest that HCaRG accelerates repair of renal proximal tubules by modulating cell proliferation of resident tubular epithelial cells and by facilitating redifferentiation.

Early nephrology consultation can have an impact on outcome of acute kidney injury patients

BACKGROUND

Patients who develop acute kidney injury (AKI) in the intensive care unit (ICU) have extremely high rates of mortality and morbidity. The objectives of this study were to compare clinical and laboratory characteristics of AKI patients evaluated and not evaluated by nephrologists in ICU and generate the hypothesis of the relationship between timing of nephrology consultation and outcome.

METHODS

We explored associations among presence and timing of nephrology consultation with ICU stay and in-ICU mortality in 148 ICU patients with AKI at a Brazilian teaching hospital from July 2008 to May 2010. Multivariable logistic regression was used to adjust confounding and selection bias.

RESULTS

AKI incidence was 30% and 52% of these AKI patients were evaluated by nephrologists. At multivariable analysis, AKI patients evaluated by nephrologists showed higher Acute Tubular Necrosis-Index Specific Score and creatinine level, more dialysis indications, lower urine output and longer ICU stay. The mortality rate was similar to AKI patients who were not evaluated. Nephrology consultation was delayed (≥ 48 h) in 62.3% (median time to consultation, 4.7 days). Lower serum creatinine levels (P = 0.009) and higher urine output (P = 0.002) were associated with delayed consultation. Delayed consultation was associated with increased ICU mortality (65.4 versus 88.2%, P < 0.001).

CONCLUSIONS

In AKI, patients evaluated by nephrologists seem to be more seriously ill than those not evaluated and present similar mortality rate. The delayed nephrology consultation can be associated with increased ICU mortality.

Outcomes following diagnosis of acute renal failure in U.S. veterans: focus on acute tubular necrosis

When patients develop acute kidney injury, a small fraction of them will develop end-stage renal disease later. The severity of renal impairment in the remaining patients is uncertain because studies have not carefully examined renal function over time or the precise timing of entry into a late stage of chronic kidney disease. To determine these factors, we used a United States Department of Veterans Affairs database to ascertain long-term renal function in 113,272 patients. Of these, 44,377 had established chronic kidney disease and were analyzed separately. A cohort of 63,491 patients was hospitalized for acute myocardial infarction or pneumonia and designated as controls. The remaining 5,404 patients had diagnostic codes indicating acute renal failure or acute tubular necrosis. Serum creatinine, estimated glomerular filtration rates, and dates of death over a 75-month period were followed. Renal function deteriorated over time in all groups, but with significantly greater severity in those who had acute renal failure and acute tubular necrosis compared to controls. Patients with acute kidney injury, especially those with acute tubular necrosis, were more likely than controls to enter stage 4 chronic kidney disease, but this entry time was similar to that of patients who initially had chronic kidney disease. The risk of death was elevated in those with acute kidney injury and chronic kidney disease compared to controls after accounting for covariates. We found that patients who had an episode of acute tubular necrosis were at high risk for the development of stage 4 disease and had a reduced survival time when compared to control patients.