230 research outputs found

    DOES PUBLIC LISTING AFFECT BANK PROFITABILITY? EVIDENCE FROM US BANKS

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    The purpose of this paper is to investigate the determinants of US bank profitability between 2002 and 2015. Specifically, we divide banks into three size groups, and focus on the impact of public listing on bank profitability. We find that small- and medium-sized public banks are less profitable than private banks of corresponding size. However, large public banks are more profitable than large private banks. Moreover, regression results indicate that loans and diversification have a positive impact on bank profitability in all size groups

    Molecular Mechanisms of Skin Aging and Rejuvenation

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    The aging process in the skin is complex and influenced by more intrinsic and extrinsic factors than any other body organ. The effects of these two types of factors overlap for the most part. The combined effects of these two aging processes also affect dermal matrix alterations. The main clinical signs of skin aging include wrinkling and irregular pigmentation, which are influenced by a combination of intrinsic and extrinsic (e.g., UV radiation, heat, smoking, and pollutants) factors. Histologically, collagen decreases, and the dermis is replaced by abnormal elastic fibers as a cause of wrinkle formation through the loss of skin elasticity. There have been numerous studies of skin aging performed to elucidate the underlying molecular mechanisms and to develop various antiaging therapeutics and preventive strategies. We summarized the molecular mechanisms and treatments of skin aging. Mainly UV radiation induces ROS formation and DNA damage, leading to increased production of MMPs and decreased production of collagen in keratinocytes and fibroblasts, which reflect the central aspects of skin aging. Besides UV radiation exposure, extrinsic factors including tobacco smoking, exposure to environmental pollutants, infrared radiation, and heat contribute to premature skin aging. Like UV radiation, these factors cause ROS formation and increase expression of MMPs, thus accelerating skin aging by inducing extracellular matrix (ECM) degradation. Accumulated collagen fibrils inhibit the new collagen synthesis and account for the further degradation of the ECM through this positive feedback loop. Accumulating evidence for molecular mechanisms of skin aging should provide clinicians with an expanding spectrum of therapeutic targets in the treatment of skin aging

    A conserved juxtacrine signal regulates synaptic partner recognition in Caenorhabditis elegans

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    <p>Abstract</p> <p>Background</p> <p>An essential stage of neural development involves the assembly of neural circuits via formation of inter-neuronal connections. Early steps in neural circuit formation, including cell migration, axon guidance, and the localization of synaptic components, are well described. However, upon reaching their target region, most neurites still contact many potential partners. In order to assemble functional circuits, it is critical that within this group of cells, neurons identify and form connections only with their appropriate partners, a process we call synaptic partner recognition (SPR). To understand how SPR is mediated, we previously developed a genetically encoded fluorescent trans-synaptic marker called NLG-1 GRASP, which labels synaptic contacts between individual neurons of interest in dense cellular environments in the genetic model organism <it>Caenorhabditis elegans</it>.</p> <p>Results</p> <p>Here, we describe the first use of NLG-1 GRASP technology, to identify SPR genes that function in this critical process. The NLG-1 GRASP system allows us to assess synaptogenesis between PHB sensory neurons and AVA interneurons instantly in live animals, making genetic analysis feasible. Additionally, we employ a behavioral assay to specifically test PHB sensory circuit function. Utilizing this approach, we reveal a new role for the secreted UNC-6/Netrin ligand and its transmembrane receptor UNC-40/Deleted in colorectal cancer (DCC) in SPR. Synapses between PHB and AVA are severely reduced in <it>unc-6 </it>and <it>unc-40 </it>animals despite normal axon guidance and subcellular localization of synaptic components. Additionally, behavioral defects indicate a complete disruption of PHB circuit function in <it>unc-40 </it>mutants. Our data indicate that UNC-40 and UNC-6 function in PHB and AVA, respectively, to specify SPR. Strikingly, overexpression of UNC-6 in postsynaptic neurons is sufficient to promote increased PHB-AVA synaptogenesis and to potentiate the behavioral response beyond wild-type levels. Furthermore, an artificially membrane-tethered UNC-6 expressed in the postsynaptic neurons promotes SPR, consistent with a short-range signal between adjacent synaptic partners.</p> <p>Conclusions</p> <p>These results indicate that the conserved UNC-6/Netrin-UNC-40/DCC ligand-receptor pair has a previously unknown function, acting in a juxtacrine manner to specify recognition of individual postsynaptic neurons. Furthermore, they illustrate the potential of this new approach, combining NLG-1 GRASP and behavioral analysis, in gene discovery and characterization.</p

    In Vitro Model of Vascularized Bone: Synergizing Vascular Development and Osteogenesis

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    Tissue engineering provides unique opportunities for regenerating diseased or damaged tissues using cells obtained from tissue biopsies. Tissue engineered grafts can also be used as high fidelity models to probe cellular and molecular interactions underlying developmental processes. In this study, we co-cultured human umbilical vein endothelial cells (HUVECs) and human mesenchymal stem cells (MSCs) under various environmental conditions to elicit synergistic interactions leading to the colocalized development of capillary-like and bone-like tissues. Cells were encapsulated at the 1∶1 ratio in fibrin gel to screen compositions of endothelial growth medium (EGM) and osteogenic medium (OM). It was determined that, to form both tissues, co-cultures should first be supplied with EGM followed by a 1∶1 cocktail of the two media types containing bone morphogenetic protein-2. Subsequent studies of HUVECs and MSCs cultured in decellularized, trabecular bone scaffolds for 6 weeks assessed the effects on tissue construct of both temporal variations in growth-factor availability and addition of fresh cells. The resulting grafts were implanted subcutaneously into nude mice to determine the phenotype stability and functionality of engineered vessels. Two important findings resulted from these studies: (i) vascular development needs to be induced prior to osteogenesis, and (ii) the addition of additional hMSCs at the osteogenic induction stage improves both tissue outcomes, as shown by increased bone volume fraction, osteoid deposition, close proximity of bone proteins to vascular networks, and anastomosis of vascular networks with the host vasculature. Interestingly, these observations compare well with what has been described for native development. We propose that our cultivation system can mimic various aspects of endothelial cell – osteogenic precursor interactions in vivo, and could find utility as a model for studies of heterotypic cellular interactions that couple blood vessel formation with osteogenesis

    In Vivo Confocal Microscopic Corneal Images in health and disease with an emphasis on extracting features and visual signatures for corneal diseases: A review study

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    There is an evolution in the demands of modern ophthalmology from descriptive findings to assessment of cellular level changes by using in vivo confocal microscopy. Confocal microscopy, by producing grey-scale images, enables a microstructural insight into the in vivo cornea in both health and disease, including epithelial changes, stromal degenerative or dystrophic diseases, endothelial pathologies, and corneal deposits and infections. Ophthalmologists use acquired confocal corneal images to identify health and disease states and then to diagnose which type of disease is affecting the cornea. This paper presents the main features of the healthy confocal corneal layers, and reviews the most common corneal diseases. It identifies the visual signature of each disease in the affected layer and extracts the main features of this disease in terms of intensity, certain regular shapes with both their size and diffusion, and some specific region of interest. These features will lead towards the development of a complete automatic corneal diagnostic system which predicts abnormalities in the confocal corneal data sets

    CO2-brine flow-through on an Utsira Sand core sample: Experimental and modelling. Implications for the Sleipner storage field

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    Sleipner (North Sea) is the world’s first commercial-scale carbon capture and storage (CCS) project, active since 1996, with ∼17 million tonnes of CO2 stored. The main reservoir, Utsira Sand, constitutes an ideal host formation of exceptionally high porosity-permeability and large lateral extent. However, the extensive seismic time-lapse, gravity and electromagnetic monitoring surveys deployed at Sleipner have not been well-supported by laboratory measurements. Here, we investigate the geophysical and geomechanical response of an Utsira core sample for the first time, using controlled inflation/depletion cycles at variable CO2-to-brine fractional flow rates. Ultrasonic P-wave velocities and attenuations are measured together with electrical resistivity (converted into CO2-saturation), along with continuous axial and radial strain monitoring. Ultrasonic velocity and attenuation data were simultaneously inverted and results extrapolated to field-scale seismic-frequencies using a new rock physics theory, which combines patchy fluid distribution and squirt flow effects. It provides a velocity-saturation relationship of practical importance to CO2 plume monitoring. Furthermore, by combining ultrasonic and deformation data, we report empirical relations between pore pressure changes and geomechanical effects in the reservoir, for different saturation ranges. Our dataset complements and constrains existing geophysical monitoring surveys at Sleipner and, more generally, improves the understanding of shallow weakly-cemented sand reservoirs

    3D bioactive composite scaffolds for bone tissue engineering

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    Bone is the second most commonly transplanted tissue worldwide, with over four million operations using bone grafts or bone substitute materials annually to treat bone defects. However, significant limitations affect current treatment options and clinical demand for bone grafts continues to rise due to conditions such as trauma, cancer, infection and arthritis. Developing bioactive three-dimensional (3D) scaffolds to support bone regeneration has therefore become a key area of focus within bone tissue engineering (BTE). A variety of materials and manufacturing methods including 3D printing have been used to create novel alternatives to traditional bone grafts. However, individual groups of materials including polymers, ceramics and hydrogels have been unable to fully replicate the properties of bone when used alone. Favourable material properties can be combined and bioactivity improved when groups of materials are used together in composite 3D scaffolds. This review will therefore consider the ideal properties of bioactive composite 3D scaffolds and examine recent use of polymers, hydrogels, metals, ceramics and bio-glasses in BTE. Scaffold fabrication methodology, mechanical performance, biocompatibility, bioactivity, and potential clinical translations will be discussed
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