The fracture behavior of Cr2AlC coatings

The erosion - and self-healing - behavior of Cr2AlC MAX phase coatings has been investigated [1]. It is well known that Cr2AlC coatings can be deposited at temperatures of around 450 °C [2], which is significantly lower than for other MAX phase systems, which often require growth temperatures around 900 °C [3]. To further explore the applicability of the Cr2AlC system in harsh environments, it is necessary to determine its mechanical response. Recent advances in micromechanical testing allow investigating the mechanical properties of hard coatings, especially the fracture behavior, which is of particular interest for several thin film applications. Furthermore, it is possible to deposit the Cr2AlC system with different microstructures, e.g. nanocrystalline or amorphous [2]. Preliminary results revealed a fracture toughness of ~2 MPam1/2 for a coating with columnar morphology. In this investigation, the effect of morphology and microstructure on the fracture toughness of Cr2AlC coatings will be presented. References [1] D. Eichner, A. Schlieter, C. Leyens, L. Shang, S. Shayestehaminzadeh, J.M. Schneider, Solid particle erosion behavior of nanolaminated Cr2AlC films, Wear. 402–403 (2018) 187–195. doi:10.1016/j.wear.2018.02.014. [2] C. Walter, D.P. Sigumonrong, T. El-Raghy, J.M. Schneider, Towards large area deposition of Cr2AlC on steel, Thin Solid Films. 515 (2006) 389–393. doi:10.1016/j.tsf.2005.12.219. [3] P. Eklund, M. Beckers, U. Jansson, H. Högberg, L. Hultman, The Mn+1AXn phases: Materials science and thin-film processing, Thin Solid Films. 518 (2010) 1851–1878. doi:10.1016/j.tsf.2009.07.184

On the interplay between microstructure, residual stress and fracture toughness of (Hf-Nb-Ta-Zr)C multi-metal carbide hard coatings

The development of sputtered coatings with improved hardness-toughness property combination is widely sought after. Multi-element ceramic carbide (Hf-Nb-Ta-Zr)C coatings with excess carbon, synthesized by DC co-sputtering is presented in this study as a promising candidate to achieve this objective. The specific roles of microstructure and residual stress are decoupled in order to understand their influence on the mechanical properties. Extensive mechanical characterization through in situ testing of focused ion beam fabricated microcantilevers and nanoindentation based approaches are adopted to quantitatively separate the effect of residual stresses on the fracture toughness of the (Hf-Nb-Ta-Zr)C coatings. Residual stress free, microcantilever testing in notched and unnotched conditions, in combination with microstructural characterization unambiguously reveals the intrinsic mechanical behavior of coatings, which solely depend on the microstructure. On the other hand, nanoindentation based testing techniques probe the influence of residual stress and microstructure on the measured mechanical properties. The segregation and thickening of carbon-rich clusters, especially to the grain boundaries with increasing deposition temperatures is speculated to lead to substantial degradation in all mechanical properties measured. An easier fracture path through grain boundaries leads to a reduction in fracture resistance, which is possibly related to carbon enrichment

Characterization of a short isoform of the kidney protein podocin in human kidney

BACKGROUND: Steroid resistant nephrotic syndrome is a severe hereditary disease often caused by mutations in the NPHS2 gene. This gene encodes the lipid binding protein podocin which localizes to the slit diaphragm of podocytes and is essential for the maintenance of an intact glomerular filtration barrier. Podocin is a hairpin-like membrane-associated protein that multimerizes to recruit lipids of the plasma membrane. Recent evidence suggested that podocin may exist in a canonical, well-studied large isoform and an ill-defined short isoform. Conclusive proof of the presence of this new podocin protein in the human system is still lacking. METHODS: We used database analyses to identify organisms for which an alternative splice variant has been annotated. Mass spectrometry was employed to prove the presence of the shorter isoform of podocin in human kidney lysates. Immunofluorescence, sucrose density gradient fractionation and PNGase-F assays were used to characterize this short isoform of human podocin. RESULTS: Mass spectrometry revealed the existence of the short isoform of human podocin on protein level. We cloned the coding sequence from a human kidney cDNA library and showed that the expressed short variant was retained in the endoplasmic reticulum while still associating with detergent-resistant membrane fractions in sucrose gradient density centrifugation. The protein is partially N-glycosylated which implies the presence of a transmembranous form of the short isoform. CONCLUSIONS: A second isoform of human podocin is expressed in the kidney. This isoform lacks part of the PHB domain. It can be detected on protein level. Distinct subcellular localization suggests a physiological role for this isoform which may be different from the well-studied canonical variant. Possibly, the short isoform influences lipid and protein composition of the slit diaphragm complex by sequestration of lipid and protein interactors into the endoplasmic reticulum

Lymphangiosis carcinomatosa in squamous cell carcinomas of larynx and hypopharynx – value of conventional evaluation and additional immunohistochemical staining of D2-40

<p>Abstract</p> <p>Background</p> <p>Recent studies revealed a predictive value of lymphatic vessel invasion (L1) for the nodal metastasizing and poor prognosis in malignant tumors at different sites. The monoclonal antibody D2-40 (podoplanin) stains specifically endothelial cells of lymphatic vessels and improves the search for L1. However, the importance of this immunohistochemical staining was not investigated in squamous cell carcinomas (SCC) of larynx and hypopharynx.</p> <p>Aim</p> <p>This study was performed to compare the diagnostic potential of convential and immunohistochemical determination of L1 in SCC of larynx and hypopharynx with special respect to the predictive value for nodal metastasizing and prognosis.</p> <p>Methods</p> <p>119 SCCs of the larynx (n = 70) respectively hypopharynx (n = 49) were investigated. The lymphatic vessel invasion was assessed by conventional method (HE stain) and immunohistochemical staining with an antibody against D2-40 (DAKO, Germany). Immunohistochemistry was performed in accordance with manufacturer's protocol. L1 was searched microscopically in a standardized magnification (×200) in serial sections of tumor samples (1 section per cm tumor diameter).</p> <p>Results</p> <p>The immunohistochemical investigation did not show significant advantages for the prediction of regional nodal metastases. Despite a low sensitivity (< 50%) in both methods, the specifity can reach 80%. The negative predictive value in both methods seems acceptable (up to 80%), whereas the positive predictive value is not higher than 64%. Cases with L1 detected either conventionally or immunohistochemically did not show a significant shorter survival than cases with L0. However, a non-significant shorter survival was found. Only in SCC of hypopharynx, a combination of both methods revealed patients with a significant worse prognosis.</p> <p>Conclusion</p> <p>The status of lymphatic vessel invasion should be documented in standardized tumor reports. A benefit of an additional immunohistochemical investigation was not found, for the daily routine HE-stain seems sufficient.</p

Genetic association study of QT interval highlights role for calcium signaling pathways in myocardial repolarization.

The QT interval, an electrocardiographic measure reflecting myocardial repolarization, is a heritable trait. QT prolongation is a risk factor for ventricular arrhythmias and sudden cardiac death (SCD) and could indicate the presence of the potentially lethal mendelian long-QT syndrome (LQTS). Using a genome-wide association and replication study in up to 100,000 individuals, we identified 35 common variant loci associated with QT interval that collectively explain ∼8-10% of QT-interval variation and highlight the importance of calcium regulation in myocardial repolarization. Rare variant analysis of 6 new QT interval-associated loci in 298 unrelated probands with LQTS identified coding variants not found in controls but of uncertain causality and therefore requiring validation. Several newly identified loci encode proteins that physically interact with other recognized repolarization proteins. Our integration of common variant association, expression and orthogonal protein-protein interaction screens provides new insights into cardiac electrophysiology and identifies new candidate genes for ventricular arrhythmias, LQTS and SCD

Comparative analysis of Neph gene expression in mouse and chicken development

Neph proteins are evolutionarily conserved members of the immunoglobulin superfamily of adhesion proteins and regulate morphogenesis and patterning of different tissues. They share a common protein structure consisting of extracellular immunoglobulin-like domains, a transmembrane region, and a carboxyl terminal cytoplasmic tail required for signaling. Neph orthologs have been widely characterized in invertebrates where they mediate such diverse processes as neural development, synaptogenesis, or myoblast fusion. Vertebrate Neph proteins have been described first at the glomerular filtration barrier of the kidney. Recently, there has been accumulating evidence suggesting a function of Neph proteins also outside the kidney. Here we demonstrate that Neph1, Neph2, and Neph3 are expressed differentially in various tissues during ontogenesis in mouse and chicken. Neph1 and Neph2 were found to be amply expressed in the central nervous system while Neph3 expression remained localized to the cerebellum anlage and the spinal cord. Outside the nervous system, Neph mRNAs were also differentially expressed in branchial arches, somites, heart, lung bud, and apical ectodermal ridge. Our findings support the concept that vertebrate Neph proteins, similarly to their Drosophila and C. elegans orthologs, provide guidance cues for cell recognition and tissue patterning in various organs which may open interesting perspectives for future research on Neph1-3 controlled morphogenesis

A functional variant in NEPH3 gene confers high risk of renal failure in primary hematuric glomerulopathies. Evidence for predisposition to microalbuminuria in the general population.

BACKGROUND: Recent data emphasize that thin basement membrane nephropathy (TBMN) should not be viewed as a form of benign familial hematuria since chronic renal failure (CRF) and even end-stage renal disease (ESRD), is a possible development for a subset of patients on long-term follow-up, through the onset of focal and segmental glomerulosclerosis (FSGS). We hypothesize that genetic modifiers may explain this variability of symptoms. METHODS: We looked in silico for potentially deleterious functional SNPs, using very strict criteria, in all the genes significantly expressed in the slit diaphragm (SD). Two variants were genotyped in a cohort of well-studied adult TBMN patients from 19 Greek-Cypriot families, with a homogeneous genetic background. Patients were categorized as "Severe" or "Mild", based on the presence or not of proteinuria, CRF and ESRD. A larger pooled cohort (HEMATURIA) of 524 patients, including IgA nephropathy patients, was used for verification. Additionally, three large general population cohorts [Framingham Heart Study (FHS), KORAF4 and SAPHIR] were used to investigate if the NEPH3-V353M variant has any renal effect in the general population. RESULTS AND CONCLUSIONS: Genotyping for two high-scored variants in 103 TBMN adult patients with founder mutations who were classified as mildly or severely affected, pointed to an association with variant NEPH3-V353M (filtrin). This promising result prompted testing in the larger pooled cohort (HEMATURIA), indicating an association of the 353M variant with disease severity under the dominant model (p = 3.0x10-3, OR = 6.64 adjusting for gender/age; allelic association: p = 4.2x10-3 adjusting for patients' kinships). Subsequently, genotyping 6,531 subjects of the Framingham Heart Study (FHS) revealed an association of the homozygous 353M/M genotype with microalbuminuria (p = 1.0x10-3). Two further general population cohorts, KORAF4 and SAPHIR confirmed the association, and a meta-analysis of all three cohorts (11,258 individuals) was highly significant (p = 1.3x10-5, OR = 7.46). Functional studies showed that Neph3 homodimerization and Neph3-Nephrin heterodimerization are disturbed by variant 353M. Additionally, 353M was associated with differential activation of the unfolded protein response pathway, when overexpressed in stressed cultured undifferentiated podocyte cells, thus attesting to its functional significance. Genetics and functional studies support a "rare variant-strong effect" role for NEPH3-V353M, by exerting a negative modifier effect on primary glomerular hematuria. Additionally, genetics studies provide evidence for a role in predisposing homozygous subjects of the general population to micro-albuminuria