A stone in the bone.

Primary hyperoxaluria (PH) is a group of diseases due to mutations in genes coding for enzymes involved in oxalate metabolism. Three types of PH are identified depending on the gene mutated. Type 1 is the most frequent with 80% of the cases, while PH2 and PH3 are rarer. The severity of renal involvement varies between the three types. Indeed, between 60% and 80% of PH1 but only 20% of PH2 patients will reach end-stage kidney disease. In PH3 patients, dialysis is uncommon. Because oxalate clearance is impaired in CKD patients, oxalate can precipitate in various organs leading to systemic oxalosis. We report an uncommon presentation of bone oxalosis associated with hypercalcemia in a dialyzed patient. This report emphasizes the difficulties to diagnose primary hyperoxaluria and the challenge of treating dialyzed patients.

Renal tubular arginase-2 participates in the formation of the corticomedullary urea gradient and attenuates kidney damage in ischemia-reperfusion injury in mice.

AIM: Arginase 2 (ARG2) is a mitochondrial enzyme that catalyses hydrolysis of l-arginine into urea and l-ornithine. In the kidney, ARG2 is localized to the S3 segment of the proximal tubule. It has been shown that expression and activity of this enzyme are upregulated in a variety of renal pathologies, including ischemia-reperfusion (IR) injury. However, the (patho)physiological role of ARG2 in the renal tubule remains largely unknown. METHODS: We addressed this question in mice with conditional knockout of Arg2 in renal tubular cells (Arg2lox/lox /Pax8-rtTA/LC1 or, cKO mice). RESULTS: We demonstrate that cKO mice exhibit impaired urea concentration and osmolality gradients along the corticomedullary axis. In a model of unilateral ischemia-reperfusion injury (UIRI) with an intact contralateral kidney, ischemia followed by 24 hours of reperfusion resulted in significantly more pronounced histological damage in ischemic kidneys from cKO mice compared to control and sham-operated mice. In parallel, UIRI-subjected cKO mice exhibited a broad range of renal functional abnormalities, including albuminuria and aminoaciduria. Fourteen days after UIRI, the cKO mice exhibited complex phenotype characterized by significantly lower body weight, increased plasma levels of early predictive markers of kidney disease progression (asymmetric dimethylarginine and symmetric dimethylarginine), impaired mitochondrial function in the ischemic kidney but no difference in kidney fibrosis as compared to control mice. CONCLUSION: Collectively, these results establish the role of ARG2 in the formation of corticomedullary urea and osmolality gradients and suggest that this enzyme attenuates kidney damage in ischemia-reperfusion injury.

Patient and doctor perspectives on HIV screening in the emergency department: A prospective cross-sectional study.

BACKGROUND: The emergency department (ED) is mentioned specifically in the Swiss HIV testing recommendations as a site at which patients can benefit from expanded HIV testing to optimise early HIV diagnosis. At our centre, where local HIV seroprevalence is 0.2-0.4%, 1% of all patients presenting to the ED are tested for HIV. Barriers to HIV testing, from the patient and doctor perspective, and patient acceptability of rapid HIV testing were examined in this study. METHODS: Between October 2014 and May 2015, 100 discrete patient-doctor encounter pairs undertook a survey in the ED of Lausanne University Hospital, Switzerland. Patients completed a questionnaire on HIV risk factors and were offered free rapid HIV testing (INSTI™). For every patient included, the treating doctor was asked if HIV testing had 1) been indicated according to the national testing recommendations, 2) mentioned, and 3) offered during the consultation. RESULTS: Of 100 patients, 30 had indications for HIV testing through risk factors or a suggestive presenting complaint (PC). Fifty patients accepted rapid testing; no test was reactive. Of 50 patients declining testing, 82% considered themselves not at risk or had recently tested negative and 16% wished to focus on their PC. ED doctors identified 20 patients with testing indications, mentioned testing to nine and offered testing to six. The main reason for doctors not mentioning or not offering testing was the wish to focus on the PC. DISCUSSION: Patients and doctors at our ED share the testing barrier of wishing to focus on the PC. Rapid HIV testing offered in parallel to the patient-doctor consultation increased the testing rate from 6% (offered by doctors) to 50%. Introducing this service would enable testing of patients not offered tests by their doctors and reduce missed opportunities for early HIV diagnosis.