Living Renal Allograft Transplantation: Diffusion-weighted MR Imaging in Longitudinal Follow-up of the Donated and the Remaining Kidney.

Purpose To determine whether diffusion-weighted (DW) magnetic resonance (MR) imaging in living renal allograft donation allows monitoring of potential changes in the nontransplanted remaining kidney of the donor because of unilateral nephrectomy and changes in the transplanted kidney before and after transplantation in donor and recipient, respectively, and whether DW MR parameters are correlated in the same kidney before and after transplantation. Materials and Methods The study protocol was approved by the local ethics committee; written informed consent was obtained. Thirteen healthy kidney donors and their corresponding recipients prospectively underwent DW MR imaging (multiple b values) in donors before donation and in donors and recipients at day 8 and months 3 and 12 after donation. Total apparent diffusion coefficient (ADCT) values were determined; contribution of microcirculation was quantified in perfusion fraction (FP). Longitudinal changes of diffusion parameters were compared (repeated-measures one-way analysis of variance with post hoc pairwise comparisons). Correlations were tested (linear regression). Results ADCT values in nontransplanted kidney of donors increased from a preexplantation value of (188 ± 9 [standard deviation]) to (202 ± 11) × 10(-5) mm(2)/sec in medulla and from (199 ± 11) to (210 ± 13) × 10(-5) mm(2)/sec in cortex 1 week after donation (P < .004). Medullary, but not cortical, ADCT values stayed increased up to 1 year. ADCT values in allografts in recipients were stable. Compared with values obtained before transplantation in donors, the corticomedullary difference was reduced in allografts (P < .03). Cortical ADCT values correlated with estimated glomerular filtration rate in recipients (R = 0.56, P < .001) but not donors. Cortical ADCT values in the same kidney before transplantation in donors correlated with those in recipients on day 8 after transplantation (R = 0.77, P = .006). FP did not show significant changes. Conclusion DW MR imaging depicts early adaptations in the remaining nontransplanted kidney of donors after nephrectomy. All diffusion parameters remained constant in allograft recipients after transplantation. This method has potential monitoring utility, although assessment of clinical relevance is needed. © RSNA, 2013 Online supplemental material is available for this article.

Pathology working group review of histopathologic specimens from three laboratory studies of diclofenac in trout.

While the pathology peer review/pathology working group (PWG) model has long been used in mammalian toxicologic pathology to ensure the accuracy, consistency, and objectivity of histopathology data, application of this paradigm to ecotoxicological studies has thus far been limited. In the current project, the PWG approach was used to evaluate histopathologic sections of gills, liver, kidney, and/or intestines from three previously published studies of diclofenac in trout, among which there was substantial variation in the reported histopathologic findings. The main objectives of this review process were to investigate and potentially reconcile these interstudy differences, and based on the results, to establish an appropriate no observed effect concentration (NOEC). Following a complete examination of all histologic sections and original diagnoses by a single experienced fish pathologist (pathology peer review), a two-day PWG session was conducted to allow members of a four-person expert panel to determine the extent of treatment-related findings in each of the three trout studies. The PWG was performed according to the United States Environmental Protection Agency (US EPA) Pesticide Regulation (PR) 94-5 (EPA Pesticide Regulation, 1994). In accordance with standard procedures, the PWG review was conducted by the non-voting chairperson in a manner intended to minimize bias, and thus during the evaluation, the four voting panelists were unaware of the treatment group status of individual fish and the original diagnoses associated with the histologic sections. Based on the results of this review, findings related to diclofenac exposure included minimal to slightly increased thickening of the gill filament tips in fish exposed to the highest concentration tested (1,000 μg/L), plus a previously undiagnosed finding, decreased hepatic glycogen, which also occurred at the 1,000 μg/L dose level. The panel found little evidence to support other reported effects of diclofenac in trout, and thus the overall NOEC was determined to be >320 μg/L. By consensus, the PWG panel was able to identify diagnostic inconsistencies among and within the three prior studies; therefore this exercise demonstrated the value of the pathology peer review/PWG approach for assessing the reliability of histopathology results that may be used by regulatory agencies for risk assessment.

A comparison of estimated glomerular filtration rates using Cockcroft−Gault and the Chronic Kidney Disease Epidemiology Collaboration estimating equations in HIV infection

OBJECTIVES: The aim of this study was to determine whether the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)- or Cockcroft-Gault (CG)-based estimated glomerular filtration rates (eGFRs) performs better in the cohort setting for predicting moderate/advanced chronic kidney disease (CKD) or end-stage renal disease (ESRD). METHODS: A total of 9521 persons in the EuroSIDA study contributed 133 873 eGFRs. Poisson regression was used to model the incidence of moderate and advanced CKD (confirmed eGFR < 60 and < 30 mL/min/1.73 m(2) , respectively) or ESRD (fatal/nonfatal) using CG and CKD-EPI eGFRs. RESULTS: Of 133 873 eGFR values, the ratio of CG to CKD-EPI was ≥ 1.1 in 22 092 (16.5%) and the difference between them (CG minus CKD-EPI) was ≥ 10 mL/min/1.73 m(2) in 20 867 (15.6%). Differences between CKD-EPI and CG were much greater when CG was not standardized for body surface area (BSA). A total of 403 persons developed moderate CKD using CG [incidence 8.9/1000 person-years of follow-up (PYFU); 95% confidence interval (CI) 8.0-9.8] and 364 using CKD-EPI (incidence 7.3/1000 PYFU; 95% CI 6.5-8.0). CG-derived eGFRs were equal to CKD-EPI-derived eGFRs at predicting ESRD (n = 36) and death (n = 565), as measured by the Akaike information criterion. CG-based moderate and advanced CKDs were associated with ESRD [adjusted incidence rate ratio (aIRR) 7.17; 95% CI 2.65-19.36 and aIRR 23.46; 95% CI 8.54-64.48, respectively], as were CKD-EPI-based moderate and advanced CKDs (aIRR 12.41; 95% CI 4.74-32.51 and aIRR 12.44; 95% CI 4.83-32.03, respectively). CONCLUSIONS: Differences between eGFRs using CG adjusted for BSA or CKD-EPI were modest. In the absence of a gold standard, the two formulae predicted clinical outcomes with equal precision and can be used to estimate GFR in HIV-positive persons.

Glutamic acid inducing kidney stone biomimicry by a brushite/gelatin composite

Brushite is a well known precursor of calcium oxalate monohydrate, the main mineral found in kidney stones having a monoclinic crystal structure. Here, we present a new method for biomimicking brushite using a single tube diffusion technique for gel growth. Brushite crystals were grown by precipitation of calcium hydrogen phosphate hydrate in a gelatin/glutamic acid network. They are compared with those produced in gel in the presence of urea. The aggregates were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and thermal gravimetric analysis (TGA). SEM revealed a change of morphology by glutamic acid from spherulitic growth to plate-shaped and mushroom-like forms consisting of crystal plates and highly ordered prismatic needles, respectively. Furthermore, brushite crystals grown in a gelatin/glutamic acid/urea network showed needle-shaped morphology being different from other brushite growth forms. The XRD method showed that cell parameters for brushite specimens were slightly larger than those of the American Mineral Society reference structure. The mushroom-like biomimetic composite bears a strong resemblance to the brushite kidney stones which may open up new future treatment options for crystal deposition diseases. Hence, suitable diets from glutamic acid rich foods could be recommended to inhibit and control brushite kidney stones.

Mineralization of calcium phosphate crystals in starch template inducing a brushite kidney stone biomimetic composite

Dicalcium phosphate dihydrate (brushite) and octacalcium phosphate (OCP) crystals are precursors of hydroxyapatite (HAp) for tooth enamel, dentine, and bones formation in living organisms. Here, we introduce a new method for biomimicking brushite and OCP in starch using single and double diffusion techniques. Brushite and OCP crystals were grown by precipitation in starch after gelation. The obtained materials were analyzed by infrared spectroscopy (IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and confocal laser scanning microscopy (CLSM). IR spectra demonstrate starch inclusion by peak shifts in the 2900–3500 cm–1 region. SEM showed two different morphologies: plate-shaped and needle-like crystals. Calcium phosphate/starch aggregates bear strong resemblance to prismatic brushite kidney stones. This may open up a clue to understand the mechanism of kidney stone formation.

Incision length for kidney transplantation does not influence short- or long-term outcome: a prospective randomized controlled trial

BACKGROUND: While previous studies suggest advantages of minimally invasive surgery in living donor nephrectomy, similar data are lacking for kidney transplant recipients. Our aim was to prospectively evaluate short- and long-term outcome for kidney transplant recipients, comparing a short transverse (ST) to a classical hockey-stick (HS) incision. METHODS: Sixty-six patients were randomized into two groups: ST vs. HS from January 2008 to May 2010. ST was defined as incision length ≤9 cm and HS as >14 cm. Perioperative data were collected, with evaluation of intra- and postoperative complications and quality of recovery (QoR) score. RESULTS: There were no significant differences in patient demographics, early or long-term postoperative pain. There were no significant differences in QoR scores between the ST and HS group. Predictive for a worse QoR was persisting incisional pain at the 30-month follow-up. Thirty-days mortality, morbidity, and long-term kidney function did not differ between the two groups (p = 1.00, p = 0.62 and p = 0.66, respectively). CONCLUSIONS: Patient satisfaction as well as graft function and patient mortality was not influenced by incision length. With patient and graft safety being paramount, especially in times of organ shortage, incision length should reflect the requirement for a successful transplantation and not be a measure of feasibility.

Common noncoding UMOD gene variants induce salt-sensitive hypertension and kidney damage by increasing uromodulin expression

Hypertension and chronic kidney disease (CKD) are complex traits representing major global health problems1,2. Multiple genome-wide association studies have identified common variants in the promoter of the UMOD gene3–9, which encodes uromodulin, the major protein secreted in normal urine, that cause independent susceptibility to CKD and hypertension. Despite compelling genetic evidence for the association between UMOD risk variants and disease susceptibility in the general population, the underlying biological mechanism is not understood. Here, we demonstrate that UMOD risk variants increased UMOD expression in vitro and in vivo. Uromodulin overexpression in transgenic mice led to salt-sensitive hypertension and to the presence of age-dependent renal lesions similar to those observed in elderly individuals homozygous for UMOD promoter risk variants. The link between uromodulin and hypertension is due to activation of the renal sodium cotransporter NKCC2. We demonstrated the relevance of this mechanism in humans by showing that pharmacological inhibition of NKCC2 was more effective in lowering blood pressure in hypertensive patients who are homozygous for UMOD promoter risk variants than in other hypertensive patients. Our findings link genetic susceptibility to hypertension and CKD to the level of uromodulin expression and uromodulin’s effect on salt reabsorption in the kidney. These findings point to uromodulin as a therapeutic target for lowering blood pressure and preserving renal function.

DYSREGULATION OF MEOX2 FOLLOWING WT1 MUTATION IN KIDNEY DEVELOPMENT AND WILMS TUMORIGENESIS

Wilms tumor (WT) is a childhood tumor of the kidney and a productive model for understanding the role of genetic alteration and interactions in tumorigenesis. The Wilms tumor gene 1 (WT1) is a transcriptional factor and one of the few genes known to have genetic alterations in WT and has been shown be inactivated in 20% of WTs. However, the mechanisms of how WT1 mutations lead to Wilms tumorigenesis and its influence on downstream genes are unknown. Since it has been established that WT1 is a transcriptional regulator, it has been hypothesized that the loss of WT1 leads to the dysregulation of downstream genes, in turn result in the formation of WTs. To identify the dysregulated downstream genes following WT1 mutations, an Affymetrix GeneChip Human Genome Array was previously conducted to assess the differentially expressed genes in the WT1-wildtype human and WT1-mutant human WTs. Approximately 700 genes were identified as being significantly dysregulated. These genes were further prioritized based on their statistical significance, fold change, chromosomal region, spatial pattern of gene expression and known or putative cellular functions. Mesenchyme homeobox 2 (MEOX2) was one of the most significantly upregulated genes in WT1-mutant WT. MEOX2 is known to play a role in cell proliferation, apoptosis, and differentiation. In addition to its biological roles, it is expressed during early kidney development in the condensed mesenchyme similar to WT1. Furthermore, the use of the Match® web-based tool from the BIOBASE Biological Data base identified a significant predicted WT1 binding site within the first intron of MEOX2. The similarity in spatial gene expression in the developing kidney and the significant predicted WT1 binding site found in the first intron of MEOX2 lead to the development of my hypothesis that MEOX2 is upregulated via a WT1-dependent manner. Here as a part of my master’s work, I have validated the Affymetrix GeneChip Human Genome Array data using an independent set of Wilms tumors. MEOX2 remained upregulated in the mutant WT1 Wilms tumor by 41-fold. Wt1 and Meox2 gene expression were assessed in murine newborn kidney; both Wt1 and Meox2 were expressed in the condensed, undifferentiated metanephric mesenchyme. I have shown that the in vivo ablation of Wt1 during embryonic development at embryonic day (E) 13.5 resulted in the slight increase of Meox2 gene expression by two fold. In order to functionally demonstrate the effect of the loss of Wt1 on Meox2 gene expression in undifferentiated metanephric mesenchyme, I have generated a kidney mesenchymal cell line to genetically ablate Wt1 in vitro by adenoviral infection. The ablation of Wt1 in the kidney mesenchymal cell line resulted in the upregulation of Meox2 by 61-fold. Moreover, the upregulation of Meox2 resulted in the significant induction of p21 and Itgb5. In addition to the dysregulation of these genes the ablation of Wt1 in the kidney mesenchymal cells resulted in decrease in cell growth and loss of cellular adherence. However, it is uncertain whether the upregulation of Meox2 caused this particular cellular phenotype. Overall, I have demonstrated that the upregulation of Meox2 is Wt1-dependent during early kidney development.

A study of xlcaax-1: Patterns of localization, possible function and usefulness as a developmental marker

Morphogenesis is the process by which the 3-dimensional structure of the developing embryo takes shape. We are studying xlcaax-1, a gene whose product can be used as a molecular marker for several morphogenetic events. We report here the cellular and subcellular localization of the xlcaax-1 protein during development of Xenopus laevis. Whole mount immunocytochemistry and immunoperoxidase staining of tissue sections showed that during development the xlcaax-1 protein accumulation was coincident with the differentiation of the epidermis, pronephros and mesonephros. In the pronephros and mesonephros the xlcaax-1 protein was localized to the basolateral membrane of differentiated tubule epithelial cells. Thus, the xlcaax-1 protein served as a marker for tubule formation and polarization during Xenopus kidney development. Xlcaax-1 may also be used as a marker for the functional differentiation of the epidermis and the epidermally derived portions of the lens and some cranial nerves. The xlcaax-1 protein was most abundant in kidney and immunogold EM analysis showed that the xlcaax-1 protein was highly enriched in the basal infoldings of the basolateral membrane of the epithelial cells in adult kidney distal tubules. The xlcaax-1 protein was also localized in other ion transporting epithelia. The localization pattern and preliminary functional assays of xlcaax-1 suggest that the protein may function in association with an ion transport channel or pump.^ Cell migration and cell-cell interactions play important roles in numerous processes during morphogenesis. One of these is the formation of the pronephric (wolffian) duct (PD), which connects the pronephros to the cloaca. It is currently accepted that in most amphibians the pronephric duct is formed by active migration of the pronephric duct rudiment (PDR) cells along a pre-determined pathway. However, there is evidence that in Xenopus, the PD may be formed entirely by in situ segregation of cells out of the lateral mesoderm. In this study, we showed, using PDR ablation and X. laevis - X. borealis chimeras, that PD elongation in Xenopus required both active cell migration and an induced recruitment of cells from the posterior lateral plate mesoderm. We also showed that PDR cell migration was limited to only a few stages during development and that this temporal control is due, at least in part, to changes in the competence of the PD pathway to support cell migration. In addition, our data suggested that an alkaline phosphatase (APase) adhesion gradient may be involved in determining this competence. ^

Intussusceptive microvascular growth: a common alternative to capillary sprouting.

Intussusceptive capillary growth represents a new principle for microvascular growth as described in the lungs of growing rats. According to this concept, the capillary network expands by the formation of slender transcapillary tissue pillars, which give rise to new vascular meshes. The process was first observed in Mercox casts of the lung microvasculature, which revealed the existence of multiple tiny holes with diameters around 1.5 microns. Consecutive transmission electron microscopic investigation of serial sections demonstrated that the holes corresponded to slender tissue pillars (Burri and Tarek, 1990). The corrosion cast technique thus appears to be an adequate screening method for intussusceptive growth. In the present investigation, Mercox casts of various vascular systems, namely, those of the eye, submandibular gland, heart, liver, stomach, small and large intestine, trachea, kidney, uterus and ovary were prepared from rats aged between 4 and 9 weeks in order to screen them for the existence of the typical tiny holes representing tissue pillars. In all organs investigated, these structures were observed in various locations to a variable degree. They were mainly encountered within dilated vascular segments or at triple or quadruple branching points of the circulation. Even in capillary networks with a three-dimensional arrangement could these pillars be detected. Intussusception thus appears to be a principle of growth appertaining to many vascular systems.

The role of phospholipase D in modulating the MTOR signaling pathway in polycystic kidney disease

The mammalian target of rapamycin (mTOR) signaling pathway is aberrantly activated in polycystic kidney disease (PKD). Emerging evidence suggests that phospholipase D (PLD) and its product phosphatidic acid (PA) regulate mTOR activity. In this study, we assessed in vitro the regulatory function of PLD and PA on the mTOR signaling pathway in PKD. We found that the basal level of PLD activity was elevated in PKD cells. Targeting PLD by small molecule inhibitors reduced cell proliferation and blocked mTOR signaling, whereas exogenous PA stimulated mTOR signaling and abolished the inhibitory effect of PLD on PKD cell proliferation. We also show that blocking PLD activity enhanced the sensitivity of PKD cells to rapamycin and that combining PLD inhibitors and rapamycin synergistically inhibited PKD cell proliferation. Furthermore, we demonstrate that targeting mTOR did not induce autophagy, whereas targeting PLD induced autophagosome formation. Taken together, our findings suggest that deregulated mTOR pathway activation is mediated partly by increased PLD signaling in PKD cells. Targeting PLD isoforms with pharmacological inhibitors may represent a new therapeutic strategy in PKD.

HDL Cholesterol Is Not Associated with Lower Mortality in Patients with Kidney Dysfunction

In the general population, HDL cholesterol (HDL-C) is associated with reduced cardiovascular events. However, recent experimental data suggest that the vascular effects of HDL can be heterogeneous. We examined the association of HDL-C with all-cause and cardiovascular mortality in the Ludwigshafen Risk and Cardiovascular Health study comprising 3307 patients undergoing coronary angiography. Patients were followed for a median of 9.9 years. Estimated GFR (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration eGFR creatinine-cystatin C (eGFRcreat-cys) equation. The effect of increasing HDL-C serum levels was assessed using Cox proportional hazard models. In participants with normal kidney function (eGFR>90 ml/min per 1.73 m(2)), higher HDL-C was associated with reduced risk of all-cause and cardiovascular mortality and coronary artery disease severity (hazard ratio [HR], 0.51, 95% confidence interval [95% CI], 0.26-0.92 [P=0.03]; HR, 0.30, 95% CI, 0.13-0.73 [P=0.01]). Conversely, in patients with mild (eGFR=60-89 ml/min per 1.73 m(2)) and more advanced reduced kidney function (eGFR<60 ml/min per 1.73 m(2)), higher HDL-C did not associate with lower risk for mortality (eGFR=60-89 ml/min per 1.73 m(2): HR, 0.68, 95% CI, 0.45-1.04 [P=0.07]; HR, 0.84, 95% CI, 0.50-1.40 [P=0.50]; eGFR<60 ml/min per 1.73 m(2): HR, 1.18, 95% CI, 0.60-1.81 [P=0.88]; HR, 0.82, 95% CI, 0.40-1.69 [P=0.60]). Moreover, Cox regression analyses revealed interaction between HDL-C and eGFR in predicting all-cause and cardiovascular mortality (P=0.04 and P=0.02, respectively). We confirmed a lack of association between higher HDL-C and lower mortality in an independent cohort of patients with definite CKD (P=0.63). In summary, higher HDL-C levels did not associate with reduced mortality risk and coronary artery disease severity in patients with reduced kidney function. Indeed, abnormal HDL function might confound the outcome of HDL-targeted therapies in these patients.

Measurements of top quark pair relative differential cross-sections with ATLAS in pp collisions at sqrts=7 TeV

Measurements are presented of differential cross-sections for top quark pair production in pp collisions at root s = 7 TeV relative to the total inclusive top quark pair production cross-section. A data sample of 2.05 fb(-1) recorded by the ATLAS detector at the Large Hadron Collider is used. Relative differential cross-sections are derived as a function of the invariant mass, the transverse momentum and the rapidity of the top quark pair system. Events are selected in the lepton (electron or muon) + jets channel. The background-subtracted differential distributions are corrected for detector effects, normalized to the total inclusive top quark pair production cross-section and compared to theoretical predictions. The measurement uncertainties range typically between 10 % and 20 % and are generally dominated by systematic effects. No significant deviations from the Standard Model expectations are observed.