434 research outputs found
Binary Gaussian Process classification of quality in the production of aluminum alloys foams with regular open cells
none2noAluminum alloys foams with homogeneous and regular open cells have been frequently proposed and used as support structures for catalytic applications. In this kind of application, the quality of produced metal foam assumes primary importance. This paper presents an application of a classifier algorithm to predict quality in the manufacturing process of aluminum alloy foams with homogeneous and regular open cells. A data analysis methodology of experimental data, which is based on Binary Gaussian Process Classification, is presented. The proposed method is a Bayesian classification method, which gets away from any assumptions about the relationship between process inputs (the geometric design parameters of the regular unit cells) and process output (probability to obtain defective foam). We demonstrate that the proposed methodology can provide an effective tool to derive a model for the prediction of quality. An investment casting process, via 3D printing of wax patterns, is considered throughout the paper. Despite this specific case study, the methodology can be exploited in different processes in which the assumptions of traditional statistical approaches could not be easily verified, e.g., additive manufacturing.openAnglani A.; Pacella M.Anglani, A.; Pacella, M
Superfluid and Pseudo-Goldstone Modes in Three Flavor Crystalline Color Superconductivity
We study the bosonic excitations in the favorite cubic three flavor
crystalline LOFF phases of QCD. We calculate in the Ginzburg-Landau
approximation the masses of the eight pseudo Nambu-Goldstone Bosons (NGB)
present in the low energy theory. We also compute the decay constants of the
massless NGB Goldstones associated to superfluidity as well as those of the
eight pseudo NGB. Differently from the corresponding situation in the
Color-Flavor-Locking phase, we find that meson condensation phases are not
expected in the present scenario.Comment: 10 pages, RevTeX4 class. Section IIIA enlarged, to appear on Phys.
Rev.
Cooling of a Compact Star with a LOFF Matter Core
Specific heat and neutrino emissivity due to direct URCA processes for quark
matter in the color superconductive Larkin-Ovchinnikov-Fulde-Ferrell (LOFF)
phase of Quantum-Chromodynamics have been evaluated. The cooling rate of
simplified models of compact stars with a LOFF matter core is estimated.Comment: 3 pages, 1 figure, to appear in the proceedings of the Helmoltz
International Summer School of Theoretical Physics on Dense Matter in Heavy
Ion Collisions and Astrophysics, JINR, Dubna, Russia, 21 Aug - 1 Sep 200
Albumin uptake in human podocytes: a possible role for the cubilin-amnionless (CUBAM) complex
Abstract Albumin re-uptake is a receptor-mediated pathway located in renal proximal tubuli. There is increasing evidence of glomerular protein handling by podocytes, but little is known about the mechanism behind this process. In this study, we found that human podocytes in vitro are committed to internalizing albumin through a receptor-mediated mechanism even after exposure to low doses of albumin. We show that these cells express cubilin, megalin, ClC-5, amnionless and Dab2, which are partners in the tubular machinery. Exposing human podocytes to albumin overload prompted an increase in CUBILIN, AMNIONLESS and CLCN5 gene expression. Inhibiting cubilin led to a reduction in albumin uptake, highlighting its importance in this mechanism. We demonstrated that human podocytes are committed to performing endocytosis via a receptor-mediated mechanism even in the presence of low doses of albumin. We also disclosed that protein overload first acts on the expression of the cubilin-amnionless (CUBAM) complex in these cells, then involves the ClC-5 channel, providing the first evidence for a possible role of the CUBAM complex in albumin endocytosis in human podocytes
Two unusual cases of Gitelman's syndrome with a complex inheritance: how the phenotype can help interpret the genotype: lesson for the clinical nephrologist
Bartter\u2019s syndrome (BS) and Gitelman\u2019s syndrome (GS) are autosomal recessive disorders with overlapping features, caused by biallelic variants in six genes encoding proteins involved in renal electrolyte homeostasis in different districts of the nephron. Here we describe two patients with a clinical diagnosis of GS with a complex inheritance whose clinical interpretation and treatment proved challenging. In one patient, compound heterozygosity for two known pathogenic variant in the SLC12A3 gene was associated with an uncommon variant in the KCNJ1 gene (one of the known BS genes). The unusual severity of GS phenotype encountered in this patient led us to hypothesize that the missense variant can act as a genetic modifier by exacerbating the severity of the disease and by inducing BS-like clinical manifestations. In the other patient, two novel likely pathogenic variants in the SLC12A3 gene were coupled with a hitherto unreported rare variant in the SLC4A1 gene; the latter\u2019s disease-causing variants have been associated with both dominant and recessive forms of distal renal tubular acidosis (dRTA). Patient\u2019s medical history (he was clinically diagnosed with incomplete hypokalemic dRTA at 10 years old) supports the hypothesis of a dual molecular diagnosis and hence of a blended phenotype
Genetics and phenotypic heterogeneity of Dent disease: the dark side of the moon
Dent disease is a rare genetic proximal tubulopathy which is under-recognized. Its phenotypic heterogeneity has led to several different classifications of the same disorder, but it is now widely accepted that the triad of symptoms low-molecular-weight proteinuria, hypercalciuria and nephrocalcinosis/nephrolithiasis are pathognomonic of Dent disease. Although mutations on the CLCN5 and OCRL genes are known to cause Dent disease, no such mutations are found in about 25-35% of cases, making diagnosis more challenging. This review outlines current knowledge regarding Dent disease from another perspective. Starting from the history of Dent disease, and reviewing the clinical details of patients with and without a genetic characterization, we discuss the phenotypic and genetic heterogeneity that typifies this disease. We focus particularly on all those confounding clinical signs and symptoms that can lead to a misdiagnosis. We also try to shed light on a concealed aspect of Dent disease. Although it is a proximal tubulopathy, its misdiagnosis may lead to patients undergoing kidney biopsy. In fact, some individuals with Dent disease have high-grade proteinuria, with or without hematuria, as in the clinical setting of glomerulopathy, or chronic kidney disease of uncertain origin. Although glomerular damage is frequently documented in Dent disease patients' biopsies, there is currently no reliable evidence of renal biopsy being of either diagnostic or prognostic value. We review published histopathology reports of tubular and glomerular damage in these patients, and discuss current knowledge regarding the role of CLCN5 and OCRL genes in glomerular function
Neutrino emission from compact stars and inhomogeneous color superconductivity
We discuss specific heat and neutrino emissivity due to direct Urca processes
for quark matter in the color superconductive Larkin-Ovchinnikov-Fulde-Ferrell
(LOFF) phase of Quantum-Chromodynamics. We assume that the three light quarks
are in a color and electrically neutral state and interact by a four
fermion Nambu-Jona Lasinio coupling. We study a LOFF state characterized by a
single plane wave for each pairing. From the evaluation of neutrino emissivity
and fermionic specific heat, the cooling rate of simplified models of compact
stars with a quark core in the LOFF state is estimated.Comment: 16 pages, 5 figures, revtex4 style. Version accepted for publication
in Phys. Rev.
Modularity map of the network of human cell differentiation
Cell differentiation in multicellular organisms is a complex process whose
mechanism can be understood by a reductionist approach, in which the individual
processes that control the generation of different cell types are identified.
Alternatively, a large scale approach in search of different organizational
features of the growth stages promises to reveal its modular global structure
with the goal of discovering previously unknown relations between cell types.
Here we sort and analyze a large set of scattered data to construct the network
of human cell differentiation (NHCD) based on cell types (nodes) and
differentiation steps (links) from the fertilized egg to a crying baby. We
discover a dynamical law of critical branching, which reveals a fractal
regularity in the modular organization of the network, and allows us to observe
the network at different scales. The emerging picture clearly identifies
clusters of cell types following a hierarchical organization, ranging from
sub-modules to super-modules of specialized tissues and organs on varying
scales. This discovery will allow one to treat the development of a particular
cell function in the context of the complex network of human development as a
whole. Our results point to an integrated large-scale view of the network of
cell types systematically revealing ties between previously unrelated domains
in organ functions.Comment: 32 pages, 7 figure
Spontaneous calcification process in primary renal cells from a medullary sponge kidney patient harbouring a GDNF mutation.
Medullary nephrocalcinosis is a hallmark of medullary sponge kidney (MSK). We had the opportunity to study a spontaneous calcification process
in vitro by utilizing the renal cells of a patient with MSK who was heterozygous for the c.-27 + 18G>A variant in the GDNF gene encoding
glial cell-derived neurotrophic factor. The cells were obtained by collagenase digestion of papillary tissues from the MSK patient and from two
patients who had no MSK or nephrocalcinosis. These cells were typed by immunocytochemistry, and the presence of mineral deposits was
studied using von Kossa staining, scanning electron microscopy analysis and an ALP assay. Osteoblastic lineage markers were studied using
immunocytochemistry and RT-PCR. Staminality markers were also analysed using flow cytometry, magnetic cell separation technology, immunocytochemistry
and RT-PCR. Starting from p2, MSK and control cells formed nodules with a behaviour similar to that of calcifying pericytes;
however, Ca2PO4 was only found in the MSK cultures. The MSK cells had morphologies and immunophenotypes resembling those of pericytes
or stromal stem cells and were positive for vimentin, ZO1, aSMA and CD146. In addition, the MSK cells expressed osteocalcin and osteonectin,
indicating an osteoblast-like phenotype. In contrast to the control cells, GDNF was down-regulated in the MSK cells. Stable GDNF knockdown
was established in the HK2 cell line and was found to promote Ca2PO4 deposition when the cells were incubated with calcifying medium by regulating
the osteonectin/osteopontin ratio in favour of osteonectin. Our data indicate that the human papilla may be a perivascular niche in which
pericyte/stromal-like cells can undergo osteogenic differentiation under particular conditions and suggest that GDNF down-regulation may have
influenced the observed phenomenon
Human parietal epithelial cells (PECs) and proteinuria in lupus nephritis: a role for ClC-5, megalin, and cubilin?
Background: Parietal epithelial cells are a heterogeneous population of cells located on Bowman’s capsule. These cells are known to internalize albumin with a still undetermined mechanism, although albumin has been shown to induce phenotypic changes in parietal epithelial cells. Proximal tubular cells are the main actors in albumin handling via the macromolecular complex composed by ClC-5, megalin, and cubilin. This study investigated the role of ClC-5, megalin, and cubilin in the parietal epithelial cells of kidney biopsies from proteinuric lupus nephritis patients and control subjects and identified phenotypical changes occurring in the pathological milieu. Methods: Immunohistochemistry and immunofluorescence analyses for ClC-5, megalin, cubilin, ANXA3, podocalyxin, CD24, CD44, HSA, and LTA marker were performed on 23 kidney biopsies from patients with Lupus Nephritis and 9 control biopsies (obtained from nephrectomies for renal cancer). Results: Two sub-populations of hypertrophic parietal epithelial cells ANXA3+/Podocalyxin−/CD44−, both expressing ClC-5, megalin, and cubilin and located at the tubular pole, were identified and characterized: the first one, CD24+/HSA−/LTA− had characteristics of human adult parietal epithelial multipotent progenitors, the second one, CD24−/LTA+/HSA+ committed to become phenotypically proximal tubular cells. The number of glomeruli presenting hypertrophic parietal epithelial cells positive for ClC-5, megalin, and cubilin were significantly higher in lupus nephritis patients than in controls. Conclusions: Our results may provide further insight into the role of hypertrophic parietal epithelial cells located at the tubular pole and their possible involvement in protein endocytosis in lupus nephritis patients. These data also suggest that the presence of hypertrophic parietal epithelial cells in Bowman's capsule represents a potential resource for responding to protein overload observed in other glomerulonephritis
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