[Symptomatic hyponatremia in a 43-year-old woman after a skiing accident with head injuries]. / Symptomatische Hyponatriämie bei einer 43-Jährigen nach Skiunfall mit Kopftrauma.

This article reports the case of a 43-year-old woman who presented to the emergency room with headache and paresthesia after a fall on the head while skiing. She had clinical signs of volume depletion and blood test showed severe hyponatremia. Cerebral imaging was unremarkable. The diagnosis of cerebral salt-wasting syndrome (CSWS) was made, which is defined by the presence of extracellular volume depletion due to a tubular defect in renal sodium transport in patients with normal adrenal and thyroid function. The disease is mostly secondary to a neurological disease or head trauma. The patient rapidly improved after volume therapy and treatment with mineralocorticoids. The differentiation of CSWS from the syndrome of inappropriate antidiuretic hormone (SIADH) secretion can be challenging but the distinction is important because treatment options are very different.

Associations between Deceased-Donor Urine MCP-1 and Kidney Transplant Outcomes.

INTRODUCTION: Existing methods to predict recipient allograft function during deceased-donor kidney procurement are imprecise. Understanding the potential renal reparative role for monocyte chemoattractant protein-1 (MCP-1), a cytokine involved in macrophage recruitment after injury, might help predict allograft outcomes. METHODS: We conducted a sub-study of the multicenter prospective Deceased Donor Study cohort, which evaluated deceased kidney donors from five organ procurement organizations from May 2010 to December 2013. We measured urine MCP-1 (uMCP-1) concentrations from donor samples collected at nephrectomy to determine associations with donor acute kidney injury (AKI), recipient delayed graft function (DGF), 6-month estimated GFR (eGFR), and graft failure. We also assessed perfusate MCP-1 concentrations from pumped kidneys for associations with DGF and 6-month eGFR. RESULTS: AKI occurred in 111 (9%) donors. Median (interquartile range) uMCP-1 concentration was higher in donors with AKI compared to donors without AKI (1.35 [0.41-3.93] ng/ml vs. 0.32 [0.11-0.80] ng/ml, p<0.001). DGF occurred in 756 (31%) recipients, but uMCP-1 was not independently associated with DGF. Higher donor uMCP-1 concentrations were independently associated with higher 6-month eGFR in those without DGF [0.77 (0.10, 1.45) ml/min/1.73m2 per doubling of uMCP1]. However, there were no independent associations between uMCP-1 and graft failure over a median follow-up of about 2 years. Lastly, perfusate MCP-1 concentrations significantly increased during pump perfusion but were not associated with DGF or 6-month eGFR. CONCLUSION: Donor uMCP-1 concentrations were modestly associated with higher recipient 6-month eGFR in those without DGF. However, the results suggest that donor uMCP-1 has minimal clinical utility given no associations with graft failure.

[Microscopic hematuria : Reasonable and risk-adapted diagnostic evaluation]. / Mikrohämaturie : Sinnvolle und risikoadaptierte Abklärung.

BACKGROUND: Microscopic hematuria that is not explained by an obvious underlying condition is a frequent and often an incidental finding that commonly triggers urological or nephrological evaluation. Potential underlying conditions range from benign to severe malignant diseases of the kidneys and urinary tract. MATERIALS AND METHODS: A nonsystematic literature search was performed, focusing on potential urological and nephrological causes of hematuria. National and international guidelines were considered and diagnostic as well as follow-up strategies are discussed. We provide a recommendation for practices in the clinical evaluation of hematuria. RESULTS: The overall prevalence for microscopic hematuria is estimated at approximately 2%, whereas risk populations show an increase to around 30%. In 13-35% of patients presenting with microscopic hematuria, a medical or surgical intervention is required. Malignant tumors of the kidneys or urinary tract can be diagnosed in 2.6-4% of all patients and in up to 25.8% of at-risk populations. "Idiopathic microscopic hematuria" without an obvious underlying medical condition accounts for approximately 80% of patients with asymptomatic hematuria. After exclusion of nephrological diseases, standard diagnostic procedures by means of medical history, physical and laboratory examination as well as ultrasound of the kidneys and the urinary tract should be performed. In the presence of risk factors, an extended diagnostic work-up using cystoscopy, urinary cytology, and cross-sectional imaging of the upper urinary tract is indicated. CONCLUSION: Evidence-based strategies of a risk-adapted diagnostic evaluation for microscopic hematuria are not available. The development of reliable clinical and molecular markers offers great potential for the identification of patients at higher risk for harboring severe diseases.

Associations of Perfusate Biomarkers and Pump Parameters With Delayed Graft Function and Deceased Donor Kidney Allograft Function.

Hypothermic machine perfusion (HMP) is increasingly used in deceased donor kidney transplantation, but controversy exists regarding the value of perfusion biomarkers and pump parameters for assessing organ quality. We prospectively determined associations between perfusate biomarkers (neutrophil gelatinase-associated lipocalin [NGAL], kidney injury molecule 1, IL-18 and liver-type fatty acid-binding protein [L-FABP]) and pump parameters (resistance and flow) with outcomes of delayed graft function (DGF) and 6-mo estimated GFR (eGFR). DGF occurred in 230 of 671 (34%) recipients. Only 1-h flow was inversely associated with DGF. Higher NGAL or L-FABP concentrations and increased resistance were inversely associated with 6-mo eGFR, whereas higher flow was associated with higher adjusted 6-mo eGFR. Discarded kidneys had consistently higher median resistance and lower median flow than transplanted kidneys, but median perfusate biomarker concentrations were either lower or not significantly different in discarded compared with transplanted kidneys. Notably, most recipients of transplanted kidneys with isolated "undesirable" biomarker levels or HMP parameters experienced acceptable 6-mo allograft function, suggesting these characteristics should not be used in isolation for discard decisions. Additional studies must confirm the utility of combining HMP measurements with other characteristics to assess kidney quality.

Associations of deceased donor kidney injury with kidney discard and function after transplantation.

Deceased donor kidneys with acute kidney injury (AKI) are often discarded due to fear of poor outcomes. We performed a multicenter study to determine associations of AKI (increasing admission-to-terminal serum creatinine by AKI Network stages) with kidney discard, delayed graft function (DGF) and 6-month estimated glomerular filtration rate (eGFR). In 1632 donors, kidney discard risk increased for AKI stages 1, 2 and 3 (compared to no AKI) with adjusted relative risks of 1.28 (1.08-1.52), 1.82 (1.45-2.30) and 2.74 (2.0-3.75), respectively. Adjusted relative risk for DGF also increased by donor AKI stage: 1.27 (1.09-1.49), 1.70 (1.37-2.12) and 2.25 (1.74-2.91), respectively. Six-month eGFR, however, was similar across AKI categories but was lower for recipients with DGF (48 [interquartile range: 31-61] vs. 58 [45-75] ml/min/1.73m(2) for no DGF, p < 0.001). There was significant favorable interaction between donor AKI and DGF such that 6-month eGFR was progressively better for DGF kidneys with increasing donor AKI (46 [29-60], 49 [32-64], 52 [36-59] and 58 [39-71] ml/min/1.73m(2) for no AKI, stage 1, 2 and 3, respectively; interaction p = 0.05). Donor AKI is associated with kidney discard and DGF, but given acceptable 6-month allograft function, clinicians should consider cautious expansion into this donor pool.

Autophagy: basic principles and relevance to transplant immunity.

Autophagy developed into a rapidly expanding field detailing its molecular mechanism and relevance in health and disease. Autophagy is an evolutionarily conserved process that summarizes a pathway in which intracellular material is degraded within the lysosome and where the macromolecular constituents are recycled. This "self-eating" process was originally described in a cell under starvation but now numerous studies established autophagy as a cellular response to stress. As a consequence, the autophagy machinery interfaces with most cellular stress-response pathways, including those involved in controlling immune response and inflammation. Autophagy also influences adaptive immunity through its effect on antigen presentation, naïve T cell repertoire selection and homeostasis and TH cell polarization. Data are emerging that dysregulated autophagy has an impact on human pathologies including infectious diseases, cancers, aging and neurodegenerative conditions. This review focuses on recent findings elucidating the ability of autophagy to be of significance in the transplant setting.

Glutathione S-transferase iso-enzymes in perfusate from pumped kidneys are associated with delayed graft function.

Accurate and reliable assessment tools are needed in transplantation. The objective of this prospective, multi-center study was to determine the associations of the alpha and pi iso-enzymes of glutathione S-transferase (GST), measured from perfusate solution at the start and end (base and post) of kidney allograft machine perfusion, with subsequent delayed graft function (DGF). We also compared GST iso-enzyme perfusate levels from discarded versus transplanted kidneys. A total of 428 kidneys were linked to outcomes as recorded by the United Network of Organ Sharing. DGF, defined as any dialysis in the first week of transplant, occurred in 141 recipients (32%). Alpha- and pi-GST levels significantly increased during machine perfusion. The adjusted relative risks (95% confidence interval) of DGF with each log-unit increase in base and post pi-GST were 1.14 (1.0-1.3) and 1.36 (1.1-1.8), respectively. Alpha-GST was not independently associated with DGF. There were no significant differences in GST values between discarded and transplanted kidneys, though renal resistance was significantly higher in discarded kidneys. We found pi-GST at the end of machine perfusion to be independently associated with DGF. Further studies should elucidate the utility of GST for identifying injured kidneys with regard to organ allocation, discard and recipient management decisions.

Costimulatory blockade-induced allograft survival requires Beclin1.

Autophagy is required for T cell homeostasis and activation-induced T cell expansion. Whether autophagy participates in tolerance induction to foreign antigens, including allografts, is unknown. We tested the role of an essential autophagy protein, Beclin1, in heart transplant survival in mice. We observed that long-term allograft survival induced by donor-specific transfusion plus anti-CD154 mAb required homozygous lymphocyte expression of Beclin1. Following adoptive transfer into allogeneic recipients, autophagy-deficient, Beclin1 heterozygous effector T cells (Teffs) exhibited enhanced proliferation with diminished cell death and increased production of interferon gamma. Whereas the induction and function of regulatory T cells (Tregs) in Beclin1 heterozygous mice were normal, Teffs from these mice were resistant to Treg-mediated suppression. Our findings identify a requisite role for Beclin1 in facilitating Teff death during tolerance induction.

When good intentions are not enough: obtaining follow-up data in living kidney donors.

The Organ Procurement Transplant Network/United Network for Organ Sharing (OPTN/UNOS) has increased the amount of data collected before and after donation and increased the duration of donor follow-up to 2 years, yet there is evidence that reporting is incomplete. We examined the frequency of missing data in the OPTN/UNOS donor follow-up registry and found that reporting rates were low, particularly for donors who may have limited access to health care. We argue that a national donor follow-up registry is essential to ensure transparency in ascertaining long-term health outcomes among all living donors and in providing assessments of quality assurance within transplant programs. We have suggested approaches to strengthen the donor follow-up registry system. These include setting clear and high standards for follow-up reporting, a system of incentives and penalties that would motivate transplant centers to comply with these standards and would encourage donors to follow-up and lifelong follow-up reporting by primary care providers. We argue that the US government must provide funding to support a donor follow-up registry that can allow for meaningful and valid conclusions, in recognition of donors' public service and to maintain trust in the system of living organ donation.

Immune reconstitution following rabbit antithymocyte globulin.

Depletional induction therapies are routinely used to prevent acute rejection and improve transplant outcome. The effects of depleting agents on T-cell subsets and subsequent T-cell reconstitution are incompletely defined. We used flow cytometry to examine the effects of rabbit antithymocyte globulin (rATG) on the peripheral T-cell repertoire of pediatric and adult renal transplant recipients. We found that while rATG effectively depleted CD45RA+CD27+ naïve and CD45RO+CD27+ central memory CD4+ T cells, it had little effect on CD45RO+CD27- CD4+ effector memory or CD45RA+CD31-, CD45RO+CD27+ and CD45RO+CD27- CD8+ T cell subsets. When we performed a kinetic analysis of CD31+ recent thymic emigrants and CD45RA+/RO+ T cells, we found evidence for both thymopoiesis and homeostatic proliferation contributing to immune reconstitution. We additionally examined the impact of rATG on peripheral CD4+Foxp3+ T cells. We found that in adults, administration of rATG-induced peripheral expansion and new thymic emigration of T cells with a Treg phenotype, while CD4+Foxp3+ T cells of thymic origin predominated in children, providing the first evidence that rATG induces Treg in vivo. Collectively our data indicate that rATG alters the balance of regulatory to memory effector T cells posttransplant, providing an explanation for how it positively impacts transplant outcome.

Inhibition of TLR4 signaling prolongs Treg-dependent murine islet allograft survival.

Toll-like receptors (TLRs) provide an important link between innate and adaptive immune system. We hypothesized that the recognition of endogenous TLR4 ligands is occurring at the time of transplantation, and these innate signals drive the inflammation and affect alloimmune responses. We confirmed that early after transplantation of allogenic islets, transcripts for TLR4 as well as potential ligands were released or up-regulated. In an allogenic islet transplantation model, genetic disruption of TLR4 on donor islets had no effect on allograft survival, whereas TLR4 deficiency in recipients lead to prolonged graft survival. Low dose rapamycin-treatment of TLR4(-/-) recipients induced permanent engraftment of 45% islet graft (p=0.005) compared to WT recipients. This prolonged graft survival was dependent on the presence of CD4(+)CD25(+)Foxp3(+) Treg. Naïve CD4(+)CD25(-) T cells cultured with the TLR4 ligand lipopolysaccharide showed enhanced IL-4, IL-6, IL-17, IFN gamma secretion and inhibited TGFbeta induced Foxp3(+)Treg generation. Thus, inhibition of recipient TLR4 activation at the time of transplantation decreases proinflammatory signals and allows Treg generation.

Factors associated with failure to list HIV-positive kidney transplant candidates.

With improved survival in the antiretroviral era, data from ongoing studies suggest that HIV patients can be safely transplanted. The disproportionate burden of HIV-related end-stage renal disease in minority populations may impose additional obstacles to successful completion of the transplant evaluation. We retrospectively reviewed 309 potentially eligible HIV patients evaluated for kidney transplant at our institution since 2000. Only 20% of HIV patients have been listed, compared to 73% of HIV-negative patients evaluated over the same period (p < 0.00001). Failure to provide documentation of CD4 and viral load (36% of candidates) was the most common reason for failure to progress beyond initial evaluation. Other factors independently associated with failure to complete the evaluation included CD4 < 200 at initial evaluation (OR 15.17; 95% CI 1.94-118.83), black race (OR 2.33; 95% CI 1.07-5.06), and history of drug use (OR 2.56; 95% CI 1.22-5.37). More efficient medical record sharing and an awareness of factors associated with failure to list HIV-positive transplant candidates may enable transplant centers to more effectively advocate for these patients.

Expression of Toll-like receptors in the kidney: their potential role beyond infection.

Toll-like receptors (TLRs) recognize both exogenous microbial components and endogenous molecules to promote immune activation. Both immune and nonimmune renal cells express TLRs, which are involved in the pathogenesis of a number of kidney diseases, including pyelonephritis, Leptospira nephritis, immune-complex glomerulonephritis, ischemic/reperfusion injury, and rejection of kidney transplant.

Combinatorial model of chemokine involvement in glomerular monocyte recruitment: role of CXC chemokine receptor 2 in infiltration during nephrotoxic nephritis.

A sequential model involving chemokines has been proposed for leukocyte extravasation into areas of inflammation; however, site-specific aspects remain to be elucidated. Hence, we studied the role of chemokines produced by mesangial (MC) or glomerular endothelial cells (GEC) and their receptors in glomerular recruitment of monocytes. Stimulation of MC with TNF-alpha up-regulated mRNA and protein of CC and CXC chemokines but not constitutive expression of the CX(3)C chemokine fractalkine. While growth-related activity (GRO)-alpha was immobilized to MC proteoglycans, monocyte chemotactic protein (MCP)-1 was secreted into the soluble phase. Firm adhesion and sequestration of monocytes on activated MC was supported by the GRO-alpha receptor CXCR2 and to a lesser extent by CX(3)CR, whereas the MCP-1 receptor CCR2 contributed to their transendothelial chemotaxis toward activated MC. In contrast, fractalkine mRNA and protein was induced by TNF-alpha in transformed rat GEC, and both CXCR2 and CX(3)CR mediated monocyte arrest on GEC in shear flow. The relevance of these mechanisms was confirmed in a rat nephrotoxic nephritis model where acute glomerular macrophage recruitment was profoundly inhibited by blocking CXCR2 or CCR2. In conclusion, our results epitomize a combinatorial model in which chemokines play specialized roles in driving glomerular monocyte recruitment and emphasize an important role for CXCR2 in macrophage infiltration during early phases of nephrotoxic nephritis.

Hyponatraemia as a complication of colonoscopy.

A case of colonoscopy-induced hyponatraemic encephalopathy led us to study the risk of hyponatraemia after gastrointestinal endoscopy. We assessed 40 patients before and after colonoscopy. 20 gastroscopy patients served as controls. Our findings show a high incidence (7.5%) of hyponatraemia after colonoscopy, in association with raised serum concentrations of arginine vasopressin. Physicians should be aware of this complication, since it may contribute to psychological and neurological symptoms after colonoscopy.

Chloride channels ClC-2 and ICln mRNA expression differs in renal epithelial ontogeny.

Development-dependent mRNA expression of the chloride channels ClC-2 and ICln was studied by quantitative reverse transcriptase-polymerase chain reaction in rat ureteric bud and cortical collecting duct primary monolayer cultures. Abundance of ClC-2 mRNA increased in ureteric bud cells between embryonic day 15 (E15) and E17, peaked at postnatal day 3 (P3), and was down-regulated at P7 when morphogenesis is complete, suggesting a specific embryonic function. Expression of ICln mRNA, in contrast, up-regulated continuously with development.

Detection of multiple vascular endothelial growth factor splice isoforms in single glomerular podocytes.

Glomerular podocytes are major determinants of filtration permselectivity in the glomerulus. Although the molecular mechanisms determining the characteristics of the glomerular filtration unit are incompletely understood, vascular endothelial growth factor (VEGF) has been implicated. To analyze this process in situ, we established a method that allows exploration of in vivo mRNA expression of podocytes using single-cell reverse transcriptase-polymerase chain reaction (RT-PCR). Microdissected mouse glomeruli were held in a patch-clamp apparatus, and single podocytes were harvested by aspiration. After lysis, the cells were reverse transcribed, and PCR was performed (45 cycles). The podocyte nature of the material was confirmed by detection of podocyte-specific mRNA (glomerular epithelial protein 1 and Wilms' tumor protein 1). Using specific oligonucleotide primers, VEGF was detected in mRNA obtained from renal cortex, single microdissected glomeruli, cultured murine podocytes, and single podocytes in situ. All cells examined expressed three VEGF isoforms (121, 165, and 189). These differ in their capacity for binding to extracellular matrix and could have different potencies regulating glomerular endothelial permeability. Our approach should allow a semiquantitative, isoform-specific evaluation of VEGF mRNA expression in podocytes during nephrogenesis and in glomerular disease.

Single cell RT-PCR analysis of ClC-2 mRNA expression in ureteric bud tip.

Embryonic epithelia at the tip of the ureteric bud (UB) face the interspace between epithelial and mesenchymal cells and are fundamentally involved in reciprocal signaling during early nephrogenesis. To characterize their membrane conductive proteins, patch-clamp and single cell RT-PCR techniques were applied to embryonic rat UBs [embryonic day 17 (day E17)] microdissected from the outer cortex. Cells at the UB tip had a high whole cell conductance (14 +/- 2 nS/10 pF, n = 8). The main fractional conductance resembled that of Ca-activated Cl channels in nonepithelial cells, with its time-dependent activation at depolarizing and inactivation at hyperpolarizing voltages. A second Cl-selective current fraction, by contrast, activated slowly during strong hyperpolarization, suggestive of a ClC-2-mediated conductance. To determine the origin of this current, cytoplasm was harvested into the patch pipette, RNA was reverse transcribed, and cDNA encoding the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) housekeeper gene or the ClC-2 Cl channel was amplified by polymerase chain reaction (PCR). GAPDH and ClC-2 PCR products were identified in 23 and 8 (out of a total of 57) single cell cDNA samples, respectively. ClC-2 PCR products with two different lengths were obtained, which might be due to two alternatively spliced ClC-2 mRNA isoforms. This first and combined approach by patch-clamp and single cell RT-PCR techniques to embryonic epithelia indicates that 1) cells at the UB tip express a phenotype remarkably different from that of postembryonic collecting duct principal cells and that 2) ClC-2 is likely to have a key role in early nephrogenesis.

Expression of glucose transporters in human peritoneal mesothelial cells.

Glucose containing solutions, the basis of peritoneal dialysis fluids, affect the proliferation and regeneration of peritoneal mesothelial cells (MsC). The aim of this study was to examine mechanisms of glucose transport into MsC, that is, the expression of facilitative glucose transporters (GLUT) and the Na(+)-dependent glucose transporter (SGLT1) in human primary MsC and a transfected MsC line. Since expression of both transporters is differentiation dependent, we investigated the effects of cell differentiation induced by culturing MsC on membranes or by addition of hexamethylene bisacetamide (HMBA; 6 mM), which enhances SGLT1 expression in LLC-PK1 cells. Levels of mRNA for GLUT1 through GLUT4 and SGLT1 were evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR). The presence of the corresponding proteins was examined by Western blotting and localized by immunofluorescence. Active, Na(+)-dependent glucose transport was assessed by alpha-methyl-D-[14C]glucopyranoside (AMG) with and without the SGLT1-specific inhibitor phlorizin and by patch clamp experiments in NaCl or choline-chloride, For Na(+) dependent glucose uptake choline chloride instead of NaCl served as negative control. Facilitative transport was assessed using 2-fluoro-2-deoxy-[14C]-D-glucose (FDG) with and without the inhibitors cytochalasin B or phloretin. Primary and transfected MsC express GLUT1 and GLUT3 mRNA while no transcripts were found for GLUT2 and GLUT4. No SGLT1 transcript was detectable in subconfluent cells. Semiquantitative RT-PCR analysis documented that the addition of the differentiation inducer HMBA to confluent cultures or growth of MsC on membranes for seven days produced a down-regulation of mRNA for GLUT1, no change for GLUT3, and a substantial increase for SGLT1 mRNA. Under these conditions MsC express SGLT1 protein and possess a Na(+)-dependent glucose uptake as assessed by AMG. Phlorizin (1 mM) inhibits AMG uptake by 30 to 40%. In patch clamp experiments the addition of extracellular glucose depolarized the membrane potential only in the presence of sodium. These results indicate that differentiated MsC express GLUT1, GLUT3, and SGLT1. Further characterization of these transport mechanisms and their regulation may help to understand the cellular effects of glucose on MsC in peritoneal dialysis.