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Now showing items 1 - 15 of 15

  • Genome-wide DNA methylation analysis in permanent atrial fibrillation

    Zhao, Guochang   Zhou, Jian   Gao, Jie   Liu, Yan   Gu, Song   Zhang, Xitao   Su, Pixiong  

    Atrial fibrillation (AF) is a highly heterogeneous genetic disease; however, the pathogenesis of AF cannot be explained by genetic variants alone. DNA methylation is a heritable method of gene expression regulation, and may be a potential regulatory mechanism in AF. Therefore, in the present study, the genome-wide DNA methylation pattern in cells derived from the left atrium of patients with permanent AF (n=3D7) was compared with that of healthy heart donors (n=3D4) with a normal sinus rhythm (SR). Enriched biological functions of the differentially methylated genes were assessed. Integrated analysis of genome-wide methylation and mRNA expression profiles was performed, and reverse transcription quantitative-polymerase chain reaction (RT-qPCR) was used to determine the expression levels of four selected genes. A total of 417 differentially methylated CpG sites were identified in the fibrillating atrium (P<0.05; vertical bar beta vertical bar>0.17); the majority of which were located in gene-body and intergenic regions outside of CpG islands. Aberrantly methylated genes participated in the activation of inflammation, sodium and potassium ion transport, fibrosis and the reduction of lipid metabolism. Hypermethylation in the AF susceptible loci, paired-like homeodomain transcription factor 2 (chromosome 4q25) and coiled-coil domain containing 141 (chromosome 2q31), as well as hypomethylation in the calcium voltage-gated channel subunit alpha 1C (chromosome 12p13) locus, were identified in all patients with AF. Of the 420 upregulated and 567 downregulated genes previously identified in patients with AF relative to those with normal SR (fold-change >2.0; P <=3D 0.05), 12 genes were hypomethylated and eight genes were hypermethylated in each group, respectively (vertical bar beta vertical bar>0.2: P<0.05). RT-qPCR analysis of four of these genes supported the modulatory effect of DNA methylation on gene expression. These results suggest that DNA methylation-mediated regulation of gene expression may serve an important role in AF pathogenesis, and several susceptible AF CpG loci were identified which may be involved in the initiation of AF.
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  • Two-Incision Totally Thoracoscopic Approach for Mitral Valve Replacement

    Zhao, Guochang   Gao, Jie   Liu, Yan   Gu, Song   Guo, Yulin   Xie, Bin   Su, Pi Xiong  

    Totally thoracosopic mitral valve replacement (MVR) has been applied to mitral stenosis for many years. Three working ports are usually necessary, among which the longest port ranges from 6 to 8 cm. This study aimed to determine the safety and feasibility of the two-incision totally thoracoscopic approach for MVR, with the longest incision of 3 cm. From January 2014 to February 2016, 90 patients with mitral valve stenosis were retrospectively analyzed. Thirty-six (40%) patients were included in the two-incision group and 54 patients were operated on using the sternotomy approach. Perioperative variables and postoperative 3-month follow-up data were analyzed. All patients underwent MVR. Tricuspid valvuloplasty was performed in 23 (25.5%) patients with the Kay technique. The mean total surgery time, cardiopulmonary bypass, and cross-clamp times were longer in the two-incision group (266 +/- 42 versus 200 +/- 38 minutes; 156 +/- 23 versus 121 +/- 21 minutes; 100 +/- 17 versus 80 +/- 17 minutes, respectively) (P < 0.05). The mean postoperative mechanical ventilation time was shorter in the two-incision group (8.6 +/- 2.5 versus 11.2 +/- 2.6 hours, respectively) (P < 0.05). The mean volume of blood drainage was less in the two-incision group (497 +/- 120 versus 730 +/- 198 mL, respectively) (P < 0.05). Reopening occurred in one (sternotomy group, 1.8%) patient. No deaths, perivalvular leakage, infectious endocarditis, atelectasis of the lungs, or moderate tricuspid regurgitation were found at the 3-month follow-up. The two-incision totally thoracoscopic approach for MVR is safe and feasible. Concomitant tricuspid valvuloplasty can be conveniently performed. However, further clinical data are needed in future studies.
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  • How and why do Chinese urban students outperform their rural counterparts?

    Zhao, Guochang   Ye, Jingjing   Li, Zhengyang   Xue, Sen  

    This paper aims to measure and understand the rural urban student cognitive ability gap in China. Using the China Education Panel Survey (CEPS) 2013/2014 data, we find that the cognitive ability test scores of urban students are approximately 1.41 points (17%) higher than those of rural students, on average. This difference is equivalent to 37 and 41% of the standard deviation of urban and rural students' test scores, respectively. Instead of the raw test score, when the cognitive ability is estimated with the 3-parameter Logistic item response theory model, the rural urban gap is somewhat reduced. The regression and Oaxaca-Blinder decomposition analyses show that nearly one-half of the rural urban gap can be accounted for by differences in observed characteristics, especially number of siblings, parental education, and interaction between parents and teachers. We then discuss the policy implications of these results and propose a few potential ways to reduce the rural urban gap in students' cognitive abilities.
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  • Agricultural land land and rural-urban migration in China: A new pattern

    Xiao, Wei   Zhao, Guochang  

    This paper investigates the effects of agricultural land on rural-urban migration and the labor market outcomes in the context of China. We employ the rural sample of the 2009 RUMiC data, which cover approximately 8000 rural households in 82 counties of China. We find that an increase in the agricultural land of a household tends to increase the household members' propensity for migration for working in cities. We also find that an increase in land significantly decreases the number of days of migration, increases the number of days of farming work, and decreases the number of days of local non-farming work. More interestingly, the negative effect on time for local non-farming work is much larger than that for non-local non-farming work. The increase in the amount of agricultural land also pushes household members to move further. These results show us a new pattern different from the literature. To explain such a difference, we compare the effect of land among different age-groups and find that the positive link between agricultural land and rural-urban migration only exists for young people. Therefore, our results may reflect the change of the role of agricultural land over time. Our finding that less agricultural land hinders rural-urban migration suggests that, to help rural residents access opportunities in cities, governments should implement policies targeting households with less agricultural land.
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  • How and why do Chinese urban students outperform their rural counterparts?

    Zhao, Guochang   Ye, Jingjing   Li, Zhengyang   Xue, Sen  

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  • An estimation of US gasoline demand: A smooth time-varying cointegration approach

    Park, Sung Y.   Zhao, Guochang  

    In this paper the U.S. gasoline demand from 1976 to 2008 is estimated using a time-varying cointegrating regression. We find that price elasticity increased rapidly during the late 1970s and then decreased until 1987. After a relatively small-scaled "increase-decrease" cycle from 1987 to 2000, the price elasticity rose again after 2000. The time-varying change of the elasticities may be explained by the proportion of gasoline consumption to income and fluctuation of the degree of necessity. The result of the error correction model shows that a deviation from a long-run equilibrium is corrected quickly, and the welfare analysis illustrates there may be a gain by shifting the tax scheme from income tax to gasoline tax. (C) 2009 Elsevier B.V. All rights reserved.
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  • Aortic Valve Replacement with Bovine Pericardium in Patients with Aortic Valve Regurgitation.

    Sheng, Weiyong   Zhao, Guochang   Chao, Yangyang   Sun, Fuqiang   Jiao, Zhouyang   Liu, Penghong   Zhang, Hang   Yao, Xingxing   Lu, Fanfan   Zhan, Haibo   Zhou, Jiawei   Song, Tao   Tao, Liang   Liu, Chao  

    This study aimed to analyze the early and mid-term outcomes of aortic valve replacement with bovine pericardium in the treatment of aortic valve regurgitation.From January 2015 to March 2018, 36 patients (19 men; mean =C2=B1 standard deviation [SD] age, 46.70 =C2=B1 16.60 years) underwent aortic valve replacement with bovine pericardium. The bovine pericardium was intraoperatively measured and shaped using an Ozaki template, according to the shape and size of the individual patient's aortic valve leaflets. Additional procedures were performed, including ventricular septal defect repair in 5 cases, mitral valve reconstruction in 6 cases, tricuspid valve reconstruction in 6 cases, and coronary artery bypass grafting in 3 cases.There were no perioperative deaths. One elderly patient with postoperative respiratory failure recovered after symptomatic treatment. One patient with frequent ventricular tachycardia after intraoperative cardiac re-jump underwent intra-aortic balloon counterpulsation (IABP), and the IABP device was successfully removed on the second postoperative day. Within the first 6 months of follow-up, there were no death events, no reoperation events, and no additional thromboembolic events. Follow-up echocardiography was performed for 6 months, with average left ventricular ejection fraction of 62.01 =C2=B1 3.21%, mean transvalvular pressure gradient of 11.17 =C2=B1 4.90 mmHg, and mean aortic valve velocity of 1.60 =C2=B1 0.58 m/s. Compared with the preoperative transthoracic echocardiography findings, the results at the six-month follow-up were statistically significant (P < 0.05). Mild aortic valve regurgitation occurred in 2 patients (5.56%), whereas other patients had no or only minimal aortic valve regurgitation (n =3D 34, 94.44%). Moderate aortic valve regurgitation occurred in one patient at 9 months after the initial operation. This was found to be due to infective endocarditis, and a biological valve was finally implanted.Aortic valve replacement with bovine pericardium in the treatment of aortic valve regurgitation is feasible, and good early and mid-term results are achieved. Long-term results need to be followed up in the future.=20
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  • Living condition among China's rural-urban migrants:recent dynamics and the inland-coastal differential

    Niu, Geng   Zhao, Guochang  

    Using data from the Rural-Urban Migration in China (RUMiC) survey, this paper evaluates the very recent dynamics of living condition among China's rural-urban migrants during 2008-2014, scrutinizing in particular the differential between the inland region and the coastal region. Along with their improved economic conditions, housing conditions of migrants have in general improved, although compared to urban locals their disadvantages persist over time. The improvement is especially fast among those migrants residing in the inland region. Multivariate regression results indicate that education, income, place of origin and family composition are important determinants of migrants' housing conditions. Finally, decomposition analysis suggests that even after controlling for those observable factors, there is still a large inland-coastal differential. Over time, China's rural-urban migrants are becoming more stable and settled in host cities. The temporary nature of China's migrants, claimed in many previous studies, might be changing. Updated and regional-specific migrant policies are needed.
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  • Is power generation really the gold measure of the Chinese economy? A conceptual and empirical assessment

    Zhang, Jin   Li, Pujiang   Zhao, Guochang  

    Amid widespread concern about the quality of the Chinese GDP data, power generation has become probably the single most cited indicator about the Chinese economy other than official statistics. For the first time, we provide an assessment on the efficacy of power generation as such an indicator, using both conceptual and empirical analyses. We show that (i) conceptually, it is somewhat misleading to use power generation as coincident indicator to infer the growth rate of GDP, due to the change of power intensity; (ii) empirically, power generation beats railway cargo and bank loan, the two other variables in the Li Keqiang index, as the best predictor in forecasting the Chinese GDP over the full sample; however, this superiority holds mainly during period of sharp change, i.e., the financial crisis period, but not when the economy is relatively stable, especially the current New Normal period. These two findings place important caveats on the common trust we have in power generation as an influential variable for measuring the Chinese economy.
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  • Anoxia-reoxygenation versus ischemia in isolated rat lungs

    Zhao, Guochang   Al-Mehdi, Abu B.   Fisher, Aron B.  

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  • Depolarization-Associated Iron Release with Abrupt Reduction in Pulmonary Endothelial Shear Stress In Situ

    Al-Mehdi, Abu B.   Zhao, Guochang   Tozawa, Kasumi   Fisher, Aron B.  

    This study evaluated the roles of endothelial cell membrane potential and reactive oxygen species (ROS) in the increase of tissue free iron during lung ischemia. Oxygenated ischemia was produced in the isolated rat lung by discontinuing perfusion while ventilation with O(2) was maintained. We have shown previously that tissue oxygenation is maintained in this model of ischemia and that biochemical changes are the result of an abrupt reduction in endothelial shear stress. With 1 hr oxygenated ischemia, generation of ROS, evaluated by oxidation of dichlorodihydrofluorescein (H(2)DCF) to fluorescent dichlorofluorescein, increased 8.0-fold, lung thiobarbituric acid reactive substances (TBARS) increased 3.4-fold, and lung protein carbonyl content increased 2.4-fold. Lung tissue free iron, measured in the lung homogenate with a fluorescent desferrioxamine derivative, increased 4.0-fold during ischemia. Pretreatment of lungs with thapsigargin abolished the increase in free iron with ischemia indicating that this effect is dependent on Ca(2+) release from intracellular stores. Perfusion of lungs with high (25 mM) K(+) to depolarize the endothelium also led to a significant increase in tissue free iron. Pretreatment of lungs with 35 mu M cromakalim, a K(+)-channel agonist, significantly inhibited both ischemia-induced tissue oxidant injury and the increase in free iron with ischemia or with high K+ perfusion. A similar increase in free iron was observed when lungs were ventilated with either O(2) or N(2) during the ischemic period or were pre-perfused with an inhibitor of ROS production (diphenyleneiodonium). These results indicate that ROS generation is not required for ischemia-mediated iron release. Thus, ROS generation and iron release with ischemia are independent although both are subsequent to endothelial cell membrane depolarization. Antiox. Redox Signal. 2, 335-345.
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  • Depolarization-associated iron release with abrupt reduction in pulmonary endothelial shear stress: Aron B. Fisher, Abu B. Al-Mehdi, Guochang Zhao, and Kasumi Tozawa, Institute for Environmental Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104

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  • Depolarization-associated iron release with abrupt reduction in pulmonary endothelial shear stress: Aron B. Fisher, Abu B. Al-Mehdi, Guochang Zhao, and Kasumi Tozawa, Institute for Environmental Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104

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  • Selenoperoxidase-dependent glutathione cycle activity in peroxide-challenged leukemia cells

    Korytowski, Witold   Bachowski, Gary J.   Geiger, Peter G.   Lin, Fubao   Zhao, Guochang   Girotti, Albert W.  

    Murine leukemia L1210 cells rendered deficient in glutathione peroxidase (GPX) and phospholipid peroxidase (PHGPX) by Se deprivation (L cntdot Se(-) cells) were found to be more sensitive to tert-butyl hydroperoxide glutathione cytotoxicity than Se-replete controls (L cntdot Se(+) cells). Human K562 cells, which express PHGPX, but not GPX, were found to be more sensitive to tert-butyl hydroperoxide (t-BuOOH) to t-BuOOH in the Se-deficient (K cntdot Se(-)) than Se-satisfied (K cntdot Se(+ )) condition. In examining the metabolic basis for selenoperoxidase-dependent resistance, we found that glucose-replete Se(-) cells reduce t-BuOOH to t-butanol far more slowly than Se(+) cells, the ratio of the first-order rate constants approximating that of the GPX activities (L1210 cells) or PHGPX activities (K562 cells). Monitoring peroxide-induced changes in GSH and GSSG gave consistent results; e.g., glucose-depleted Lx cntdot Se( + ) cells exhibited a first order loss of GSH that was substantially faster than that of glucose-depleted L cntdot Se( - ) cells. Under the conditions used, exhibited a first order loss of of GSH to GSSG could be stoichiometrically reversed by resupplying D-glucose, indicating that no significant lysis or GSSG efflux and/or interchange had taken place. The apparent first-order rate constant for GSH decay increased progressively for L1210 cells expressing a range of GPX activities from apprx 5% to 100%, demonstrating that peroxide detoxification is strictly dependent on enzyme content. The initial rate of 14CO-2 release from D-(1-144C)glucose supplied in the medium was much greater fpr L cntdot Se(+) or K cntdot Se(+) cells than for their respective Se(-) counterparts, consistent with greater hexose monophosphate shunt activity in the former. These results highlight the importance of selenoperoxidase action in the glutathione cycle as a means by which tumor cells cope with hydroperoxide stress. hydroperoxide stress.
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  • State,market,and family:housing inequality among the young generation in urban China

    Niu, Geng   Zhao, Guochang  

    Housing is critical to people's prosperity and wellbeing. In particular, housing status is closely linked to young people's life opportunities in many domains. With skyrocketing housing prices in many cities, housing outcomes of the current young generation in China are receiving increased attention. In this study, we examine the recent pattern of housing inequality among the young generation in urban China based on a large-scale national representative survey conducted in 2015, and we explore the importance of different types of factors. From an intragenerational perspective, we investigate the relative strengths between socialist institutions and market mechanisms. We also take into account the intergenerational channel by studying the impact of family background variables. We find substantial inequality in terms of home ownership, living space, and housing wealth among young people. While market ability variables, such as income and education, significantly affect housing consumption, institutional factors, such as the household registration (hukou) system, work units, and administrative rank, still play important roles in contemporary China. Furthermore, the impact of parental socioeconomic and political status is also nontrivial. In particular, the hukou status of young people and their parents has a sizable impact on housing consumption. China's policymakers should pay more attention to the housing needs of young people and take concrete measures to expand the equality of opportunities.
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