3,706 research outputs found

    Synthesis of bio-based thermoplastic polyurethane elastomers containing isosorbide and polycarbonate diol and their biocompatible properties.

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    A new family of highly elastic polyurethanes (PUs) partially based on renewable isosorbide were prepared by reacting hexamethylene diisocyanate with a various ratios of isosorbide and polycarbonate diol 2000 (PCD) via a one-step bulk condensation polymerization without catalyst. The influence of the isorsorbide/PCD ratio on the properties of the PU was evaluated. The successful synthesis of the PUs was confirmed by Fourier transform-infrared spectroscopy and (1)H nuclear magnetic resonance. The resulting PUs showed high number-average molecular weights ranging from 56,320 to 126,000 g mol(-1) and tunable Tg values from -34 to -38℃. The thermal properties were determined by differential scanning calorimetry and thermogravimetric analysis. The PU films were flexible with breaking strains from 955% to 1795% at from 13.5 to 54.2 MPa tensile stress. All the PUs had 0.9-2.8% weight lost over 4 weeks and continual slow weight loss of 1.1-3.6% was observed within 8 weeks. Although the cells showed a slight lower rate of proliferation than that of the tissue culture polystyrene as a control, the PU films were considered to be cytocompatible and nontoxic. These thermoplastic PUs were soft, flexible and biocompatible polymers, which open up a range of opportunities for soft tissue augmentation and regeneration

    TRPCs: Influential Mediators in Skeletal Muscle

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    Ca2+ itself or Ca2+-dependent signaling pathways play fundamental roles in various cellular processes from cell growth to death. The most representative example can be found in skeletal muscle cells where a well-timed and adequate supply of Ca2+ is required for coordinated Ca2+-dependent skeletal muscle functions, such as the interactions of contractile proteins during contraction. Intracellular Ca2+ movements between the cytosol and sarcoplasmic reticulum (SR) are strictly regulated to maintain the appropriate Ca2+ supply in skeletal muscle cells. Added to intracellular Ca2+ movements, the contribution of extracellular Ca2+ entry to skeletal muscle functions and its significance have been continuously studied since the early 1990s. Here, studies on the roles of channel proteins that mediate extracellular Ca2+ entry into skeletal muscle cells using skeletal myoblasts, myotubes, fibers, tissue, or skeletal muscle-originated cell lines are reviewed with special attention to the proposed functions of transient receptor potential canonical proteins (TRPCs) as store-operated Ca2+ entry (SOCE) channels under normal conditions and the potential abnormal properties of TRPCs in muscle diseases such as Duchenne muscular dystrophy (DMD)

    Toxicity assessment of modified Cry1Ac1 proteins and genetically modified insect-resistant Agb0101 rice

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    Insect-resistant Agb0101 rice was recently developed by modifying the cry1ac1 gene by changing codon usage changes relative to the native truncated cry1ac1 gene. To assess the toxicity of genetically modified Agb0101 rice, we conducted bioinfomational comparisons of the amino acid sequences that are not similar to known toxic proteins. Sufficient quantities of mCry1Ac1 protein were produced in Escherichia coli for in vitro evaluation and animal study. We compared the amino acid sequences and molecular mass. There have the same amino acid sequences and molecular masses after purifying the modified Cry1Ac1 (mCry1Ac1) protein from highly expressed bacteria and genetically modified rice were identical. We also investigated the acute and 90-days oral toxicities. No adverse effects were observed in mice following acute oral exposure to 2,000 mg/ kg body weight mCry1Ac1 protein of body weight and 90 days oral exposure to Agb0101. These results indicate that mCry1Ac1 proteins and Agb0101 rice demonstrate no adverse effects in these tests when applied via gavage and feed, respectively.Key words: Modified Cry1Ac1, food safety assessment, toxicity, insect- resistant rice Agb0101

    Facteurs de Risque, EpidĂ©miologie et Prise en Charge de la Grossesse Extra-utĂ©rine Rompue (GEUR) au Service de GynĂ©cologie et d’ObstĂ©trique de l’HĂŽpital National Ignace Deen du CHU de Conakry en 2022

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    Introduction : urgence gynĂ©cologique frĂ©quente, dĂ©couverte fortuite aux urgences mĂ©dicales et ou chirurgicales dans un tableau d’anĂ©mie. L’objectif de ce travail Ă©tait d’étudier les facteurs de risque, Ă©pidĂ©miologie, et prise en charge de la grossesse extra-utĂ©rine rompue au service de gynĂ©cologie et d’obstĂ©trique de l’hĂŽpital national Ignace Deen du CHU de Conakry en 2022. MĂ©thodes : il s’agissait d’une Ă©tude descriptive transversale Ă  recrutement rĂ©trospectif. Elle a Ă©tĂ© menĂ©e au service de gynĂ©cologie et d’obstĂ©trique de l’hĂŽpital national Ignace Deen du CHU de Conakry du 1er janvier  2019 au 31 DĂ©cembre 2022 soit une pĂ©riode de trois ans. Ont Ă©tĂ© Ă©tudiĂ©es les variables se rapportant aux facteurs de risque, Ă©pidĂ©miologie, et la prise en charge de la GEUR dans notre contexte de travail. Nous avons utilisĂ© le logiciel Excel pour l’analyse des donnĂ©es. RĂ©sultats : frĂ©quence de la GEUR dans notre Ă©tude Ă©tait 1,26 % sur l’ensemble des interventions gynĂ©cologiques, les tranches d’ñge les plus reprĂ©sentĂ©es Ă©taient celles de 20-24 ans et 30-34 ans dans 32,69%, plus de la moitiĂ© Ă©tait cĂ©libataire 69,23%, sans profession, non scolarisĂ© respectivement 64,23% et 42,31%, primipares dans 49,04%.  Parmi les facteurs de risque (FDR) retrouvĂ©s dans notre sĂ©rie, figuraient les antĂ©cĂ©dents de :  l’infection gĂ©nitale 46,15%, les fausses couches spontanĂ©es 10,58%, la contraception par microprogestatif 16,34%. La prise en charge a Ă©tĂ© exclusivement chirurgicale (100%), associĂ©e Ă  la transfusion sanguine comme moyen de rĂ©animation dans 95,16%. Conclusion : la grossesse extra-utĂ©rine rompue est une urgence mĂ©dicochirurgicale frĂ©quente, le diagnostic prĂ©coce traine les pas dans les pays Ă  faibles ressources.   Introduction : a frequent gynecological emergency, discovered incidentally in medical and/or surgical emergencies in the setting of anemia. The aim of this study was to investigate the risk factors and management of ectopic pregnancy in the gynecology and obstetrics department of the Ignace Deen National Hospital of Conakry University Hospital in 2022. Methods : This was a descriptive study with retrospective recruitment. It was conducted at the gynecology and obstetrics department of the CHU Ignace Deen national hospital in Conakry from January 1, 2019 to December 31, 2022, a three-year period. Variables relating to risk factors, epidemiology and management of GEUR in our working context were studied. We used Excel software for data analysis. Results : The frequency of GEUR in our study was 1.26% of all gynaecological procedures, the most represented age groups were 20-24 and 30-34 years with 32.69%, more than half were single 69.23%, without profession, not in school respectively 64.23% and 42.31%, primiparous in 49.04%.  Among the risk factors found in our series were a history of : genital infection 46,15%, spontaneous miscarriage 10.58%, microprogestogen contraception 16.34%. Management was exclusively surgical (100%), associated with blood transfusion as a means of resuscitation in 95.16% Conclusion : Ruptured ectopic pregnancy is a frequent medico-surgical emergency, early diagnosis is lagging behind in low-resource countries

    Aggregation of human salivary Ca-proteinates in the presence of simple carbohydrates in vitro

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    The effect of 8 polyols and 14 aldoses or ketoses on the spontaneous aggregation of Ca-proteinates was followed spectrophotometrically in supernatants and filtrates of human mixed saliva. Each carbohydrate was added to the saliva samples at 37°C and the precipitated material was analyzed for protein, total carbohydrate and Ca. Based on their effect on aggregation, the carbohydrates could be divided into three groups: 1) those that showed no effect on aggregation: D-xylose, D-ribose and i-erythritol, 2) those that inhibited aggregation strongly: xylitol, Dsorbitol and D-mannitoi, and 3) those that inhibited aggregation moderately: glucose, fructose and sucrose. The inhibitory effect of the above polyols on the aggregation of Ca-proteinates varied greatly among the saliva donors, and correlated positively with the turbidity of the saliva and its protein content more than with the Ca-concentration or the pH of the saliva sample. It is suggested that inhibition of aggregation shown the most clearly for xylitol, sorbitol and mannitol manifests itself as a retardation of the final, irreversible aggregation of those glycoproteins that already exist in a precipitated form and which are responsible for the turbidity of saliva.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75574/1/j.1600-0722.1986.tb01376.x.pd

    The Seroepidemiology of Haemophilus influenzae Type B Prior to Introduction of an Immunization Programme in Kathmandu, Nepal.

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    Haemophilus influenzae type b (Hib) is now recognized as an important pathogen in Asia. To evaluate disease susceptibility, and as a marker of Hib transmission before routine immunization was introduced in Kathmandu, 71 participants aged 7 months-77 years were recruited and 15 cord blood samples were collected for analysis of anti-polyribosylribitol phosphate antibody levels by enzyme-linked immunosorbent assay. Only 20% of children under 5 years old had levels considered protective (>0.15 ”g/ml), rising to 83% of 15-54 year-olds. Prior to introduction of Hib vaccine in Kathmandu, the majority of young children were susceptible to disease

    Anisotropic Terahertz Emission from Bi2Se3 Thin Films with Inclined Crystal Planes

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    We investigate the surface states of topological insulator (TI) Bi2Se3 thin films grown on Si nanocrystals and Al2O3 substrates by using terahertz (THz) emission spectroscopy. Compared to bulk crystalline Bi2Te2Se, film TIs exhibit distinct behaviors in the phase and amplitude of emitted THz radiation. In particular, Bi2Se3 grown on Al2O3 shows an anisotropic response with a strong modulation of the THz signal in its phase. From x-ray diffraction, we find that the crystal plane of the Bi2Se3 films is inclined with respect to the plane of the Al2O3 substrate by about 0.27 degrees. This structural anisotropy affects the dynamics of photocarriers and hence leads to the observed anisotropic response in the THz emission. Such relevance demonstrates that THz emission spectroscopy can be a sensitive tool to investigate the fine details of the surface crystallography and electrostatics of thin film TIs.1112Ysciescopu

    IL-12p40 Homodimer Ameliorates Experimental Autoimmune Arthritis

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    IL-23 is the key cytokine that induces the expansion of Th17 cells. It is composed of p19 and p40 subunits of IL-12. The p40 subunit binds competitively to the receptor of IL-23 and blocks its activity. Our aim was to assess the preventive and therapeutic effect of the IL-12p40 homodimer (p40)(2) subunit in autoimmune arthritis animal models. In the current study, using IL-1R antagonist-knockout mice and a collagen-induced arthritis model, we investigated the suppressive effect of (p40)(2) on inflammatory arthritis. We demonstrated that the recombinant adenovirus-expressing mouse (p40)(2) model prevented the development of arthritis when given before the onset of arthritis. It also decreased the arthritis index and joint erosions in the mouse model if transferred after arthritis was established. (p40)(2) inhibited the production of inflammatory cytokines and Ag-specific T cell proliferation. It also induced CD4(+)CD25(+)Foxp3 regulatory T (Treg) cells in vitro and in vivo, whereas the generation of retinoic acid receptor-related organ receptor gamma t and Th17 cells was suppressed. The induction of Treg cells and the suppression of Th17 cells were mediated via activated STAT5 and suppressed STAT3. Our data suggest that (p40)(2) suppressed inflammatory arthritis successfully. This could be a useful therapeutic approach in autoimmune arthritis to regulate the Th17/Treg balance and IL-23 signaling.1156Ysciescopu

    Crystalline TiO2 protective layer with graded oxygen defects for efficient and stable silicon-based photocathode

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    © 2018, The Author(s). The trade-offs between photoelectrode efficiency and stability significantly hinder the practical application of silicon-based photoelectrochemical devices. Here, we report a facile approach to decouple the trade-offs of silicon-based photocathodes by employing crystalline TiO2 with graded oxygen defects as protection layer. The crystalline protection layer provides high-density structure and enhances stability, and at the same time oxygen defects allow the carrier transport with low resistance as required for high efficiency. The silicon-based photocathode with black TiO2 shows a limiting current density of ~35.3 mA cm-2 and durability of over 100 h at 10 mA cm-2 in 1.0 M NaOH electrolyte, while none of photoelectrochemical behavior is observed in crystalline TiO2 protection layer. These findings have significant suggestions for further development of silicon-based, III–V compounds and other photoelectrodes and offer the possibility for achieving highly efficient and durable photoelectrochemical devices
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