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951.
Karen L. Soldano Melanie E. Garrett Heidi L. Cope J. Michael Rusnak Nathen J. Ellis Kaitlyn L. Dunlap Allison E. Ashley‐Koch 《Birth defects research. Part B, Developmental and reproductive toxicology》2013,98(5):365-373
Neural tube defects (NTDs) are caused by improper neural tube closure during the early stages of embryonic development. NTDs are hypothesized to have a complex genetic origin and numerous candidate genes have been proposed. The nitric oxide synthase 3 (NOS3) G594T polymorphism has been implicated in risk for spina bifida, and interactions between that single nucleotide polymorphism (SNP) and the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism have also been observed. To evaluate other genetic variation in the NO pathway in the development of NTDs, we examined all three NOS genes: NOS1, NOS2, and NOS3. Using 3109 Caucasian samples in 745 families, we evaluated association in the overall dataset and within specific phenotypic subsets. Haplotype tagging SNPs in the NOS genes were tested for genetic association with NTD subtypes, both for main effects as well as for the presence of interactions with the MTHFR C677T polymorphism. Nominal main effect associations were found with all subtypes, across all three NOS genes, and interactions were observed between SNPs in all three NOS genes and MTHFR C677T. Unlike the previous report, the most significant associations in our dataset were with cranial subtypes and the AG genotype of rs4795067 in NOS2 (p = 0.0014) and the interaction between the rs9658490 G allele in NOS1 and MTHFR 677TT genotype (p = 0.0014). Our data extend the previous findings by implicating a role for all three NOS genes, independently and through interactions with MTHFR, in risk not only for spina bifida, but all NTD subtypes. 相似文献
952.
Janet Y. Uriu‐Adams Sarah G. Obican Carl L. Keen 《Birth defects research. Part C, Embryo today : reviews》2013,99(1):24-44
The essentiality of vitamin D for normal growth and development has been recognized for over 80 years, and vitamin D fortification programs have been in place in the United States for more than 70 years. Despite the above, vitamin D deficiency continues to be a common finding in certain population groups. Vitamin D deficiency has been suggested as a potential risk factor for the development of preeclampsia, and vitamin D deficiency during infancy and early childhood is associated with an increased risk for numerous skeletal disorders, as well as immunological and vascular abnormalities. Vitamin D deficiency can occur through multiple mechanisms including the consumption of diets low in this vitamin and inadequate exposure to environmental ultraviolet B rays. The potential value of vitamin D supplementation in high‐risk pregnancies and during infancy and early childhood is discussed. Currently, there is vigorous debate concerning what constitutes appropriate vitamin D intakes during early development as exemplified by differing recommendations from the Institute of Medicine Dietary Reference Intake report and recent recommendations by the Endocrine Society. As is discussed, a major issue that needs to be resolved is what key biological endpoint should be used when making vitamin D recommendations for the pregnant woman and her offspring. Birth Defects Research (Part C) 99:24–44, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
953.
During growth and development, the skin expands to cover the growing skeleton and soft tissues by constantly responding to the intrinsic forces of underlying skeletal growth as well as to the extrinsic mechanical forces from body movements and external supports. Mechanical forces can be perceived by two types of skin receptors: (1) cellular mechanoreceptors/mechanosensors, such as the cytoskeleton, cell adhesion molecules and mechanosensitive (MS) ion channels, and (2) sensory nerve fibres that produce the somatic sensation of mechanical force. Skin disorders in which there is an abnormality of collagen [e.g. Ehlers–Danlos syndrome (EDS)] or elastic (e.g. cutis laxa) fibres or a malfunction of cutaneous nerve fibres (e.g. neurofibroma, leprosy and diabetes mellitus) are also characterized to some extent by deficiencies in mechanobiological processes. Recent studies have shown that mechanotransduction is crucial for skin development, especially hemidesmosome maturation, which implies that the pathogenesis of skin disorders such as bullous pemphigoid is related to skin mechanobiology. Similarly, autoimmune diseases, including scleroderma and mixed connective tissue disease, and pathological scarring in the form of keloids and hypertrophic scars would seem to be clearly associated with the mechanobiological dysfunction of the skin. Finally, skin ageing can also be considered as a degenerative process associated with mechanobiological dysfunction. Clinically, a therapeutic strategy involving mechanoreceptors or MS nociceptor inhibition or acceleration together with a reduction or augmentation in the relevant mechanical forces is likely to be successful. The development of novel approaches such as these will allow the treatment of a broad range of cutaneous diseases. 相似文献
954.
Maria‐Giuliana Vannucchi Chiara Traini Mirko Manetti Lidia Ibba‐Manneschi Maria‐Simonetta Faussone‐Pellegrini 《Journal of cellular and molecular medicine》2013,17(9):1099-1108
Telocytes (TC), a cell population located in the connective tissue of many organs of humans and laboratory mammals, are characterized by a small cell body and extremely long and thin processes. Different TC subpopulations share unique ultrastructural features, but express different markers. In the gastrointestinal (GI) tract, cells with features of TC were seen to be CD34‐positive/c‐kit‐negative and several roles have been proposed for them. Other interstitial cell types with regulatory roles described in the gut are the c‐kit‐positive/CD34‐negative/platelet‐derived growth factor receptor α (PDGFRα)‐negative interstitial cells of Cajal (ICC) and the PDGFRα‐positive/c‐kit‐negative fibroblast‐like cells (FLC). As TC display the same features and locations of the PDGFRα‐positive cells, we investigated whether TC and PDGFRα‐positive cells could be the same cell type. PDGFRα/CD34, PDGFRα/c‐kit and CD34/c‐kit double immunolabelling was performed in full‐thickness specimens from human oesophagus, stomach and small and large intestines. All TC in the mucosa, submucosa and muscle coat were PDGFRα/CD34‐positive. TC formed a three‐dimensional network in the submucosa and in the interstitium between muscle layers, and an almost continuous layer at the submucosal borders of muscularis mucosae and circular muscle layer. Moreover, TC encircled muscle bundles, nerve structures, blood vessels, funds of gastric glands and intestinal crypts. Some TC were located within the muscle bundles, displaying the same location of ICC and running intermingled with them. ICC were c‐kit‐positive and CD34/PDGFRα‐negative. In conclusion, in the human GI tract the TC are PDGFRα‐positive and, therefore, might correspond to the FLC. We also hypothesize that in human gut, there are different TC subpopulations probably playing region‐specific roles. 相似文献
955.
956.
957.
Sung‐Hae Park Jongchul Lim Young Soo Kwon In Young Song Jong Min Choi Seulki Song Taiho Park 《Liver Transplantation》2013,3(2):184-192
Nanoporous network polymer nanocomposites with tunable pore size for size‐dependent selective ion transport are successfully prepared via the surface‐induced cross‐linking polymerization of methyl methacrylate (MMA) and 1,6‐hexanediol diacrylate (HDDA) on the surfaces of nanocrystalline TiO2 particles. The morphologies of the porous network polymer layer and nanopores were investigated by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE‐SEM), and Brunauer–Emmett–Teller (BET) experiments. The porous layer size‐selectively screened the ions that contacted the nanocrystalline TiO2 particles, as demonstrated by ion conductivity measurements, electrochemical impedance spectroscopy (EIS), and transient absorption spectroscopy (TAS). 相似文献
958.
Olga Malinkiewicz Thais Grancha Agustin Molina‐Ontoria Alejandra Soriano Hicham Brine Henk J. Bolink 《Liver Transplantation》2013,3(4):472-477
Simple bilayer solar cells, using commercially available cationic cyanine dyes as donors and evaporated C60 layer as an acceptor are prepared. Cyanine dyes with absorption maxima of 578, 615 and 697 nm having either perchlorate or hexafluorophosphate counter‐ions are evaluated. The perchlorate dye leads to cells with S‐shape current‐voltage curves; only the dyes with the hexafluorophosphate counter‐ions lead to efficient solar cells. When the wide bandgap dyes are employed, S‐shape current‐voltage curves are obtained when the conductive polymer PEDOT:PSS is used as hole transport layer. Substitution of PEDOT:PSS with MoO3 leads to cells with more rectangular current–voltage curves and high fill factors. Additionally, the cells using the MoO3 layer for hole extraction lead to high open circuit voltages of 0.9 V. In the case that a low bandgap hexafluorophosphate dye is used with the HOMO above that of the PEDOT:PSS the cell performance is independent on the type of hole transport layer employed. Using this approach, bilayer solar cells are obtained with power efficiencies ranging from 1.8 to 2.9% depending on the particular dye employed. These are impressive numbers for bilayer solar cell that are partially solution processed in ambient conditions. 相似文献
959.
960.
The catalyst layer of the cathode is arguably the most critical component of low‐temperature fuel cells and carbon dioxide (CO2) electrolysis cells because their performance is typically limited by slow oxygen (O2) and CO2 reduction kinetics. While significant efforts have focused on developing cathode catalysts with improved activity and stability, fewer efforts have focused on engineering the catalyst layer structure to maximize catalyst utilization and overall electrode and system performance. Here, we study the performance of cathodes for O2 reduction and CO2 reduction as a function of three common catalyst layer preparation methods: hand‐painting, air‐brushing, and screen‐printing. We employed ex‐situ X‐ray micro‐computed tomography (MicroCT) to visualize the catalyst layer structure and established data processing procedures to quantify catalyst uniformity. By coupling structural analysis with in‐situ electrochemical characterization, we directly correlate variation in catalyst layer morphology to electrode performance. MicroCT and SEM analyses indicate that, as expected, more uniform catalyst distribution and less particle agglomeration, lead to better performance. Most importantly, the analyses reported here allow for the observed differences over a large geometric volume as a function of preparation methods to be quantified and explained for the first time. Depositing catalyst layers via a fully‐automated air‐brushing method led to a 56% improvement in fuel cell performance and a significant reduction in electrode‐to‐electrode variability. Furthermore, air‐brushing catalyst layers for CO2 reduction led to a 3‐fold increase in partial CO current density and enhanced product selectivity (94% CO) at similar cathode potential but a 10‐fold decrease in catalyst loading as compared to previous reports. 相似文献