144 research outputs found

    Impacts of Land Use Change on the Regional Climate: A Structural Equation Modeling Study in Southern China

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    With the frequent human activities operating on the earth, the impacts of land use change on the regional climate are increasingly perceptible. Under the background of the rapid urbanization, understanding the impacts of land use change on the regional climate change is vital and significant. In this study, we investigated the relationships between land use change and regional climate change through a structural equation model. Southern China was selected as the study area for its rapid urbanization and different structure of land use among its counties. The results indicate that the path coefficients of “vegetation,” “Urban and surrounding area,” and “other” to “climate” are −0.42, 0.20, and 0.46, respectively. Adding vegetation area is the main method to mitigate regional climate change. Urban and surrounding area and other areas influence regional climate by increasing temperature and precipitation to a certain extent. Adding grassland and forestry, restraining sprawl of built-up area, and making the most use of unused land are efficient ways to mitigate the regional climate change in Southern China. The results can provide feasible recommendations to land use policy maker

    An Improved Method for Calculating Bending Moment and Shearing Force of Beam in Numerical Modelling

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    In view of the problem that it is difficult to obtain the displacement, internal force and damage status from one beam model established in most numerical analysis models, an improved method for calculating bending moment and shearing force is presented in this paper, which can change this situation. This method portrays how to obtain the internal force from model established using 3-D solid element which can be able to show the failure process easily. The research results are as follows: (1) Deflection equation of beam established using 3-D solid element can be fitted by extracting displacement value of each node on the axis, thus bending moment and shearing force value can be directly figured out by putting the equation of deflection curve into approximately differential equation of deflection curve. (2) The reliability of the results calculated in this method would be easily affected by force, shape of cross section and the highest degree of polynomial, etc. When the beam is in a state of small deformation and the highest degree of polynomial is kept between 20 and 30, the results will be more reliable, besides, beam model whose shape of the cross section is rectangular is more suitable for the method than the circular one. (3) This method can always be applied to beam model, no matter its constraint conditions and loading conditions are complex or not

    Engineered Microenvironment for Manufacturing Human Pluripotent Stem Cell-Derived Vascular Smooth Muscle Cells

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    Human pluripotent stem cell-derived vascular smooth muscle cells (hPSC-VSMCs) are of great value for disease modeling, drug screening, cell therapies, and tissue engineering. However, producing a high quantity of hPSC-VSMCs with current cell culture technologies remains very challenging. Here, we report a scalable method for manufacturing hPSC-VSMCs in alginate hydrogel microtubes (i.e., AlgTubes), which protect cells from hydrodynamic stresses and limit cell mass to \u3c400 \u3eμm ensure efficient mass transport. The tubes provide cells a friendly microenvironment, leading to extremely high culture efficiency.We have shown that hPSC-VSMCs can be generated in 10 days with high viability, high purity, and high yield (~5.0 x 108 cells/mL). Phenotype and gene expression showed that VSMCs made in AlgTubes and VSMCs made in 2D cultures were similar overall. However, AlgTube-VSMCs had higher expression of genes related to vasculature development and angiogenesis, and 2D-VSMCs had higher expression of genes related to cell death and biosynthetic processes

    A Scalable and Efficient Bioprocess for Manufacturing Human Pluripotent Stem Cell-Derived Endothelial Cells

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    Endothelial cells (ECs) are of great value for cell therapy, tissue engineering, and drug discovery. Obtaining high-quantity and -quality ECs remains very challenging. Here, we report a method for the scalable manufacturing of ECs from human pluripotent stem cells (hPSCs). hPSCs are expanded and differentiated into ECs in a 3D thermoreversible PNIPAAm-PEG hydrogel. The hydrogel protects cells from hydrodynamic stresses in the culture vessel and prevents cells from excessive agglomeration, leading to high-culture efficiency including high-viability (\u3e90%), high-purity (\u3e80%), and high-volumetric yield (2.0 x 107 cells/mL). These ECs (i.e., 3D-ECs) had similar properties as ECs made using 2D culture systems (i.e., 2D-ECs). Genome-wide gene expression analysis showed that 3D-ECs had higher expression of genes related to vasculature development, extracellular matrix, and glycolysis, while 2D-ECs had higher expression of genes related to cell proliferation

    Comparative study of differentiating human pluripotent stem cells into vascular smooth muscle cells in hydrogel-based culture methods

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    Vascular smooth muscle cells (VSMCs), which provides structural integrity and regulates the diameter of vasculature, are of great potential for modeling vascular-associated diseases and tissue engineering. Here, we presented a detailed comparison of differentiating human pluripotent stem cells (hPSCs) into VSMCs (hPSCs-VSMCs) in four different culture methods, including 2-dimensional (2D) culture, 3-dimensional (3D) PNIPAAm-PEG hydrogel culture, 3-dimensional (3D) alginate hydrogel culture, and transferring 3- dimensional alginate hydrogel culture to 2-dimensional (2D) culture. Both hydrogel-based culture methods could mimic in vivo microenvironment to protect cells from shear force, and avoid cells agglomeration, resulting in the extremely high culture efficiency (e.g., high viability, high purity and high yield) compared with 2D culture. We demonstrated hPSC-VSMCs produced from hydrogel-based culture methods had better contractile phenotypes and the potential of vasculature formation. The transcriptome analysis showed the hPSC-VSMCs derived from hydrogel-based culture methods displayed more upregulated genes in vasculature development, angiogenesis and blood vessel development, extracellular matrix compared with 2D culture. Taken together, hPSC-VSMCs produced from hydrogel-based culture system could be applied in various biomedical fields, and further indicated the suitable development of alginate hydrogel for industrial production by taking all aspects into consideration

    Electrical impedance tomography as a bedside assessment tool for COPD treatment during hospitalization

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    For patients with chronic obstructive pulmonary disease (COPD), the assessment of the treatment efficacy during hospitalization is of importance to the optimization of clinical treatments. Conventional spirometry might not be sensitive enough to capture the regional lung function development. The study aimed to evaluate the feasibility of using electrical impedance tomography (EIT) as an objective bedside evaluation tool for the treatment of acute exacerbation of COPD (AECOPD). Consecutive patients who required hospitalization due to AECOPD were included prospectively. EIT measurements were conducted at the time of admission and before the discharge simultaneously when a forced vital capacity maneuver was conducted. EIT-based heterogeneity measures of regional lung function were calculated based on the impedance changes over time. Surveys for attending doctors and patients were designed to evaluate the ease of use, feasibility, and overall satisfaction level to understand the acceptability of EIT measurements. Patient-reported outcome assessments were conducted. User’s acceptance of EIT technology was investigated with a five-dimension survey. A total of 32 patients were included, and 8 patients were excluded due to the FVC maneuver not meeting the ATS criteria. Spirometry-based lung function was improved during hospitalization but not significantly different (FEV1 %pred.: 35.8% ± 6.7% vs. 45.3% ± 8.8% at admission vs. discharge; p = 0.11. FVC %pred.: 67.8% ± 0.4% vs. 82.6% ± 5.0%; p = 0.15. FEV1/FVC: 0.41 ± 0.09 vs. 0.42 ± 0.07, p = 0.71). The symptoms of COPD were significantly improved, but the correlations between the improvement of symptoms and spirometry FEV1 and FEV1/FVC were low (R = 0.1 and −0.01, respectively). The differences in blood gasses and blood tests were insignificant. All but one EIT-based regional lung function parameter were significantly improved after hospitalization. The results highly correlated with the patient-reported outcome assessment (R > 0.6, p < 0.001). The overall acceptability score of EIT measurement for both attending physicians and patients was high (4.1 ± 0.8 for physicians, 4.5 ± 0.5 for patients out of 5). These results demonstrated that it was feasible and acceptable to use EIT as an objective bedside evaluation tool for COPD treatment efficacy

    Hyperbaric oxygen therapy as rescue therapy for pediatric frosted branch angiitis with Purtscher-like retinopathy: A case report

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    IntroductionFrosted branch angiitis (FBA) is an uncommon uveitis characterized by fulminant retinal vasculitis. Purtscher-like retinopathy (PuR) is a rare retinal angiopathy associated with a non-traumatic etiology. Both FBA and PuR can cause profound visual impairments.Case reportWe describe the case of a 10-year-old male who presented with sudden bilateral painless visual loss due to FBA with concurrent PuR, with notable viral prodrome 1 month prior to presentation. Systemic investigations revealed a recent herpes simplex virus 2 infection with a high titer of IgM, positive antinuclear antibody (ANA) (1:640), and abnormal liver function tests. After administration of systemic corticosteroids, anti-viral agents, and subsequent immunosuppressive medications, the FBA was gradually alleviated. However, fundoscopy and optical coherence tomography (OCT) revealed persistent PuR and macular ischemia. Hence, hyperbaric oxygen therapy was administered as a rescue strategy, which resulted in gradual bilateral visual acuity improvement.ConclusionHyperbaric oxygen therapy may be a beneficial rescue treatment for retinal ischemia secondary to FBA with PuR

    Endogenous and exogenous galectin-3 promote the adhesion of tumor cells with low expression of MUC1 to HUVECs through upregulation of N-cadherin and CD44

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    Tumor cell-endothelial adhesion is one of the key steps in tumor cell haematogenous dissemination in metastasis and was previously shown to be mediated by interaction of galectin-3 with the transmembrane mucin protein MUC1. In this study, the effect of exogenous as well as endogenous galectin-3 on adhesion of two cell lines (low MUC1-expressing human prostate cancer PC-3M cells and non-small-cell lung cancer A549 cells) to monolayer of umbilical vein endothelial cells (HUVECs) was investigated. We found that suppression of endogenous galectin-3 expression reduced tumor cell adhesion to HUVECs and also decreased cell invasion and migration. Exogenous galectin-3 promoted tumor cell adhesion to HUVECs by entering cells. Both exogenous and endogenous galectin-3 upregulated the expression of β-catenin and increased β-catenin nuclear accumulation, and subsequently upregulated the expression of N-cadherin and CD44. We deduced that both exogenous as well as endogenous galectin-3 promoted low MUC1-expressing cancer cell adhesion to HUVECs by increasing the expression of N-cadherin and CD44 via an increase of nuclear β-catenin accumulation. These results were confirmed further by using a β-catenin/TCF transcriptional activity inhibitor, N-cadherin or CD44 siRNAs. Taken together, our results suggest a new molecular mechanism of galectin-3-mediated cell adhesion in cancer metastasis

    Impact of Urbanization and Land-Use Change on Surface Climate in Middle and Lower Reaches of the Yangtze River, 1988–2008

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    Land-use/land cover change (LUCC) is one of the fundamental causes of global environmental change. In recent years, understanding the regional climate impact of LUCC has become a hot-discussed topic worldwide. Some studies have explored LUCC impact on regional climate in specific cities, provinces, or farming areas. However, the quick-urbanized areas, which are highly influenced by human activities, have the most severe land-use changes in developing countries, and their climatic impact cannot be ignored. This study aims to identify the impact of land-use change coupled with urbanization on regional temperature and precipitation in the metropolitan areas of middle and lower reaches of the Yangtze River in China by means of spatial analysis and numeric methods. Based on the exploration of land-use change and climate change during 1988–2008, the impact of land-use transition from non-built-up area to built-up area on temperature and precipitation was analyzed. The results indicated that the land-use conversion has affected the regional temperature with an increasing effect in the study area, while the influence on precipitation was not so significant. The results can provide useful information for spatial planning policies in consideration of regional climate change
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