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Altered polarity and expression of H+ -ATPase without ultrastructural changes in kidneys of Dent's disease patients. Background. Dent's disease is a proximal tubule (PT) disorder characterized by low-molecular-weight proteinuria (LWMP) that may be associated with hypercalciuria, nephrocalcinosis, and renal failure. It is caused by inactivating mutations of the renal chloride channel ClC-5, which colocalizes with the vacuolar H+ -ATPase in PT cells and α-type intercalated cells. Examinations of knockout mice have established the role of ClC-5 in PT endocytosis, but the consequences of ClC-5 mutations on the polarity of H+ -ATPase and other plasma membrane proteins remain unknown. Methods. We have studied renal biopsies from eight patients with Dent's disease, due to inactivating ClC-5 mutations, by light and electron microscopy, and by immunohistochemical staining. All patients exhibited LMWP, and renal function ranged from normal to end-stage renal failure. Results. Light microscopy revealed either normal renal architecture or glomerulosclerosis, tubular dedifferentiation and atrophy, and mild interstitial fibrosis. Focal, hyaline casts, sometimes calcified, were identified at all stages. Electron microscopy did not reveal any ultrastructural abnormalities in PT cells, and the endocytic apparatus was apparently normal. However, immunohistochemical studies demonstrated a consistent inversion of H+ -ATPase polarity in PT cells to a basolateral distribution contrasting with its apical location in the normal kidney. This inversion of polarity was specific for H+ -ATPase and did not affect distribution of aminopeptidase, megalin, and Na+ /K+ -ATPase. Furthermore, apical H+ -ATPase expression was absent in α-type intercalated cells. Conclusion. ClC-5 mutations are associated with modifications in the polarity and expression of H+ -ATPase, but not... [ABSTRACT FROM AUTHOR]

The contribution of Na+/H+ exchange (achieved by NHE proteins) to the regulation of β-cell cytosolic pHc, and the role of pHc changes in glucose-induced insulin secretion are disputed and were examined here. Using real-time PCR, we identified plasmalemmal NHE1 and intracellular NHE7 as the two most abundant NHE isoforms in mouse islets. We, therefore, compared insulin secretion, cytosolic free Ca2+ ([Ca2+]c) and pHc in islets from normal mice and mice bearing an inactivating mutation of NHE1 (Slc9A1-swe/swe). The experiments were performed in HCO-3/CO2 or HEPES/NaOH buffers. PCR and functional approaches showed that NHE1 mutant islets do not express compensatory pH-regulating mechanisms. NHE1 played a greater role than HCO-3-dependent mechanisms in the correction of an acidification imposed by a pulse of NH4Cl. In contrast, basal pHc (in low glucose) and the alkalinization produced by high glucose were independent of NHE1. Dimethylamiloride, a classic blocker of Na+/H+ exchange, did not affect pHc but increased insulin secretion in NHE1 mutant islets, indicating unspecific effects. In control islets, glucose similarly increased [Ca2+]c and insulin secretion in HCO-3 and HEPES buffer, although pHc changed in opposite directions. The amplification of insulin secretion that glucose produces when [Ca2+]c is clamped at an elevated level by KCl was also unrelated to pHc and pHc changes. All effects of glucose on [Ca2+]c and insulin secretion proved independent of NHE1. In conclusion, NHE1 protects -cells against strong acidification, but has no role in stimulus-secretion coupling. The changes in pHc produced by glucose involve HCO-3-dependent mechanisms. Variations in β-cell pHc are not causally related to changes in insulin secretion. [ABSTRACT FROM AUTHOR]

Background: Aristolochic acid nephropathy (AAN) is a rapidly progressive interstitial nephropathy linked to the exposure to aristolochic acid (AA) and characterized by extensive fibrosis and urothelial atypia. Although the fibrotic process has been documented in extrarenal tissues, the involvement of the peritoneum, as well as the efficacy of peritoneal dialysis in AAN patients, remain uncertain.Methods: The structure of the peritoneal membrane and the expression of basic fibroblast growth factor (bFGF), collagen type III, endothelial nitric oxide synthase (eNOS), and aquaporin-1 (AQP1) were investigated in peritoneal biopsies from an index AAN patient, four other AAN patients, four regular peritoneal dialysis patients, and two controls. Similar methods were used to investigate a rabbit model of AAN after intraperitoneal exposure to high-dose AA. AA-DNA adducts were screened by 32P-postlabeling analysis.Results: The AAN patients had renal failure, renal fibrosis, and urothelial atypia. The peritoneum of AAN patients had a normal structure, lacked cellular atypia, and, in comparison with regular peritoneal dialysis patients and controls, did not show abnormal regulation of fibrotic and endothelial markers. Furthermore, specific AA-DNA adducts were not identified in the peritoneum of AAN patients. In contrast, AA-DNA adducts were detected in peritoneal and kidney tissues of all exposed rabbits, and one of them developed a malignant mesothelioma.Conclusion: These data demonstrate the lack of fibrotic and vascular alterations and the absence of cellular atypia in the peritoneum from AAN patients. Thus, peritoneal dialysis should not be discouraged in these patients. Nevertheless, studies in a rabbit model of high-dose AA exposure may suggest a potential risk of peritoneal malignancy. [ABSTRACT FROM AUTHOR]

• Inspired by multi-view representation learning, we propose a scheme casting adversarial examples as a secondary view. • We propose and analyze our loss for learning representations with shared information between clean and adversarial samples. • We demonstrate that our method achieves improved robust vs. natural accuracy tradeoffs over several attacks and datasets. We consider the problem of improving the adversarial robustness of neural networks while retaining natural accuracy. Motivated by the multi-view information bottleneck formalism, we seek to learn a representation that captures the shared information between clean samples and their corresponding adversarial samples while discarding these samples' view-specific information. We show that this approach leads to a novel multi-objective loss function, and we provide mathematical motivation for its components towards improving the robust vs. natural accuracy tradeoff. We demonstrate enhanced tradeoff compared to current state-of-the-art methods with extensive evaluation on various benchmark image datasets and architectures. Ablation studies indicate that learning shared representations is key to improving performance. [ABSTRACT FROM AUTHOR]

Currently, several immunotherapies and BACE (Beta Site APP Cleaving Enzyme) inhibitor approaches are being tested in the clinic for the treatment of Alzheimer's disease. A crucial mechanism-related safety concern is the exacerbation of microhemorrhages, which are already present in the majority of Alzheimer patients. To investigate potential safety liabilities of long-term BACE inhibitor therapy, we used aged amyloid precursor protein (APP) transgenic mice (APP23), which robustly develop cerebral amyloid angiopathy. T 2 *-weighted magnetic resonance imaging (MRI), a translational method applicable in preclinical and clinical studies, was used for the detection of microhemorrhages throughout the entire brain, with subsequent histological validation. Three-dimensional reconstruction based on in vivo MRI and serial Perls' stained sections demonstrated a one-to-one matching of the lesions thus allowing for their histopathological characterization. MRI detected small Perls' positive areas with a high spatial resolution. Our data demonstrate that volumetric assessment by noninvasive MRI is well suited to monitor cerebral microhemorrhages in vivo. Furthermore, 3 months treatment of aged APP23 with the potent BACE-inhibitor NB-360 did not exacerbate microhemorrhages in contrast to Aβ-antibody β1. These results substantiate the safe use of BACE inhibitors regarding microhemorrhages in long-term clinical studies for the treatment of Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Experimental diabetes induces functional and structural changes in the peritoneum. Background. Peritoneal dialysis (PD) is an established renal replacement therapy in diabetic patients, but the influence of diabetes on the peritoneal membrane (PM) remains debated. We have used functional, biochemical and molecular studies in vivo and in vitro to substantiate the changes induced by diabetes and hyperglycemia in the PM. Methods. Peritoneal equilibration tests were performed 2, 4, and 6 weeks after induction of diabetes with streptozotocin (STZ) in rats. Morphological analyses, determination of nitric oxide synthase (NOS) activities, and expression studies for NOS isoforms and advanced glycation end products (AGE) were performed in parallel. Additional studies were conducted in diabetic rats treated with insulin, non-diabetic rats fed with urea, and cultured bovine aortic endothelial cells (BAEC). Results. In comparison with controls, diabetic rats were characterized by: increased permeability for small solutes and decreased sodium sieving; capillary proliferation; increased endothelial NOS (eNOS) and AGE immunoreactivity; up-regulation of eNOS and down-regulation of neuronal NOS; and increased NOS activity in the PM. The changes, which culminated at week 6, were prevented by chronic insulin treatment in diabetic rats. In contrast to hyperglycemia, hyperosmolality alone did not induce functional or structural changes in the PM. Studies in BAEC showed that high glucose incubation led to increased activity and expression of eNOS, a prerequisite for vascular proliferation. Conclusions. These data demonstrate that chronic hyperglycemia is associated with functional and structural changes in the peritoneum that parallel with selective regulation of NOS isoforms and AGE deposits. The alterations are prevented by insulin treatment, which suggests that adequate control of diabetes can preserve PM integrity in diabetic patients prior to PD. [ABSTRACT FROM AUTHOR]