[Symptomatic hyponatremia in a 43-year-old woman after a skiing accident with head injuries]

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.

[Microscopic hematuria : Reasonable and risk-adapted diagnostic evaluation]

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 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 to predict allograft outcomes.

Methods

We conducted a substudy of the multicenter prospective Deceased Donor Study cohort that evaluated deceased kidney donors from 5 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 glomerular filtration rate (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 donors (9%). The median (interquartile range) uMCP-1 concentration was higher in donors with AKI compared with 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 recipients (31%), but uMCP-1 was not independently associated with DGF. Higher donor uMCP-1 concentrations were independently associated with a higher 6-month eGFR in those without DGF (0.77 [0.10–1.45] ml/min per 1.73 m² per doubling of uMCP1). However, there were no independent associations between uMCP-1 and graft failure over a median follow-up of ∼2 years. Lastly, perfusate MCP-1 concentrations significantly increased during pump perfusion but were not associated with DGF or 6-month eGFR.

Discussion

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.

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.

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.

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.

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.

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.

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.

Analysis of mouse glomerular podocyte mRNA by single-cell reverse transcription-polymerase chain reaction

Selective investigation of glomerular podocytes is not possible using conventional methods in vivo. Analysis of glomerular epithelium-derived cells in culture yields dubious results because of the rapid dedifferentiation of podocytes. We developed a modification of the polymerase chain reaction (PCR) method previously used to analyze cultured neurons. Podocytes harvested from freshly dissected glomeruli are ideal target cells for this modified, single cell reverse transcription-PCR method to reproducibly identify specific mRNA species from resident intact podocytes in vivo.

Effects of hydroxyethyl starch-deferoxamine on arachidonic acid metabolism and small bowel wall perfusion in early sepsis

The effects of hydroxyethyl starch-conjugated deferoxamine (HES-DFO), a macromolecular iron chelator, were investigated on eicosanoid release and bowel wall perfusion following cecal ligation puncture (CLP) in rats. Animals were randomly given an intravenous dose of 3.0 ml of HES-DFO or either vehicle (HES) or 9.0 ml saline immediately following completion of the CLP procedure. At 30, 60, 120, and 240 min after sepsis induction, blood pressure and bowel perfusion were measured. The animals were sacrificed and blood was collected for subsequent analysis of thromboxane, prostacyclin, and prostaglandin F2 alpha. The tissue content of energy-rich phosphates was determined in small-bowel samples at each time point. The antioxidative HES-DFO therapy did not diminish the eicosanoid release after CLP when compared with either HES-treated or saline-infused rats. However, treatment with the polymeric iron chelator resulted in an impaired bowel wall perfusion that was not reflected in alterations in total adenine nucleotide content or in energy charge. Considering hemodynamic and biochemical endpoints, these results are contradictory to the hypothesis that iron-driven oxygen radicals are major determinants of the eicosanoid release that is elevated following CLP-induced sepsis.

Protective effects of hydroxyethyl starch-deferoxamine in early sepsis

The protective effects of hydroxyethyl starch-conjugated deferoxamine (HES-DFO), a macromolecular iron chelator, on the initial pathophysiological cascade in septic shock were evaluated following cecal ligation puncture (CLP) in rats. Animals were given an intravenous dose of 3.0 mL of either vehicle (HES) or HES-DFO immediately following completion of the CLP procedure. Animals were sacrificed 30, 60, 120, and 240 min following CLP, and samples of lung, kidney, bowel, and liver were collected for subsequent analysis of glutathione, myeloperoxidase, and evidence for lipid peroxidation based on measurement of thiobarbituric acid reactive substances and conjugated dienes. In addition, the endotoxin levels were determined in the plasma and histomorphological examination was conducted on tissue samples collected at each time point. At almost all time points, a reduction in lipid peroxidation was noted in the HES-DFO-treated rats (p < .05). Glutathione and myoloperoxidase levels were less affected. Lung tissue from animals receiving HEs demonstrated marked microatelectases, septal destruction, and splicing of basal membranes, which were greatly attenuated in animals having received HES-DFO. Similarly, tubulotoxic and mitochondrial damages observed in kidney samples from HES-treated animals were noticeably reduced in the animals having received the chelator. Liver and gut samples demonstrated unspecific inflammatory injury in both groups of animals. In summary, oxygen radical-mediated tissue damage occurs rapidly following CLP-induced sepsis. Based on histological and biochemical endpoints, treatment with the polymeric iron chelator, HES-DFO, significantly attenuates systemic oxidant injury, the degree of protection being most impressive in the lung and kidney.