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Background and Aims Rapid identification and treatment of acute kidney injury can help to restore kidney function. In order to differentiate between prerenal AKI and intrinsic AKI, we perform a urine chemistry test to determine the function of the renal tubule. However, there is no report that it is helpful to arrive at the hospital as early as possible and to perform these urine chemistry tests as soon as possible. Method We analyzed the timing of urinary chemistry in AKI patients who were admitted to our hospital through the emergency room for 3 years and divided into two groups. Early group was defined as patients who performed the test within 3 h of arrival in the emergency room. Late group was defined as patients who were late or not. The prognostic factors were change in 30 day eGFR and duration of hospital stay. We also compared the usefulness of urine chemistry test between pre renal AKI and intrinsic AKI in each group. Results The changes of eGFR after 30 days in each group are 41.6 ± 27.6 mL/min/1.73 m2 (Early group, n = 92) vs 30.4 ± 26.8 mL/min/1.73 m2 (Late group, n = 180) (P = 0.0013). Early group patients were discharged more quickly than patients in the late group (Hospital day: 11.5 ± 10.1 vs 13.8 ± 10.5, P = 0.0450). When analyzed according to the causes of AKI, these changes showed differences in prerenal AKI rather than intrinsic AKI(Figure). Conclusion A urine chemistry test is a test to help determine the cause of AKI. Based on the results of urine chemistry performed within 3 h after arrival at the hospital, patients with AKI who visited the emergency room had better improved kidney function and less hospitalization.

Background Colistin (polymyxin E) is an important constituent of the polymyxin class of cationic polypeptide antibiotics. Intrarenal oxidative stress can contribute to colistin-induced nephrotoxicity. Nicotinamide adenine dinucleotide 3-phosphate oxidases (Noxs) are important sources of reactive oxygen species. Among the various types of Noxs, Nox4 is predominantly expressed in the kidney. Objectives We investigated the role of Nox4 and benefit of Nox4 inhibition in colistin-induced acute kidney injury using in vivo and in vitro models. Methods Human proximal tubular epithelial (HK-2) cells were treated with colistin with or without NOX4 knockdown, or GKT137831 (most specific Nox1/4 inhibitor). Effects of Nox4 inhibition on colistin-induced acute kidney injury model in Sprague-Dawley rats were examined. Results Nox4 expression in HK-2 cells significantly increased following colistin exposure. SB4315432 (transforming growth factor-β1 receptor I inhibitor) significantly inhibited Nox4 expression in HK-2 cells. Knockdown of NOX4 transcription reduced reactive oxygen species production, lowered the levels of pro-inflammatory markers (notably mitogen-activated protein kinases) implicated in colistin-induced nephrotoxicity and attenuated apoptosis by altering Bax and caspase 3/7 activity. Pretreatment with GKT137831 replicated these effects mediated by downregulation of mitogen-activated protein kinase activities. In a rat colistin-induced acute kidney injury model, administration of GKT137831 resulted in attenuated colistin-induced acute kidney injury as indicated by attenuated impairment of glomerulus function, preserved renal structures, reduced expression of 8-hydroxyguanosine and fewer apoptotic cells. Conclusions Collectively, these findings identify Nox4 as a key source of reactive oxygen species responsible for kidney injury in colistin-induced nephrotoxicity and highlight a novel potential way to treat drug-related nephrotoxicity.

BACKGROUND: Novel, biocompatible peritoneal dialysis (PD) solutions have become available in recent years. In 2001, low glucose degradation products (GDP), neutral pH solutions became commercially available in Korea. To date, there are no reports regarding the large scale adoption of these solutions in clinical practice and regarding what, if any, impact these solutions have on patient outcomes. METHODS: Using a database of almost 4000 patients treated by PD in Korea, we conducted a prospective, longitudinal observational study documenting the patterns of use of one novel low GDP solution (balance, Fresenius Medical Care, St Wendel, Germany) in 1909 PD incident patients between 1 January 2002 and midyear 2005. Outcomes including patient and technique survival and peritonitis rates were analysed using univariate and multivariate analysis. RESULTS: Prescription of low GDP solutions reached between 70 and 80% by the year 2003 and persisted at this level. Patients prescribed low GDP PD solution tended to be younger and were more likely to be treated in centres with larger enrollment in the database. Survival of diabetic patients treated with the new PD solution was identical to that of the non-diabetic patients treated with standard PD fluids (PDF) and treatment with low GDP PDF independently reduced the relative risk (RR) of death (RR = 0.613; CI 0.50-0.74; P < 0.00001) in a proportional hazards model which included age, diabetes and centre experience. In a univariate analysis, low GDP PD solution was associated with a longer technique survival (P = 0.049) but this effect was not significant in multivariate analysis. No significant differences in peritonitis-free interval or peritonitis rate could be attributed to the prescribed PDF. CONCLUSION: Prescription of low GDP, pH-neutral PD solutions has rapidly increased in Korea. This change has resulted in a significant improvement in patient and technique survival without any measurable change in peritonitis incidence or rate. Reasons for the improved patient survival cannot be determined from this analysis and require further study.