214 results on '"Feng Xu"'
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2. A dynamic traffic signal scheduling system based on improved greedy algorithm.
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Guangling Sun, Rui Qi, Yulong Liu, and Feng Xu
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Medicine ,Science - Abstract
Urbanization has led to accelerated traffic congestion, posing a significant obstacle to urban development. Traditional traffic signal scheduling methods are often inefficient and cumbersome, resulting in unnecessary waiting times for vehicles and pedestrians, exacerbating the traffic situation. To address this issue, this article proposes a dynamic traffic signal scheduling system based on an improved greedy algorithm. Unlike conventional approaches, we introduce a reward function and a cost model to ensure fair scheduling plans. A constraint function is also established, and the traffic signal scheduling is iterated through the feasible matrix using the greedy algorithm to simplify the decision-making process and enhance solution efficiency. Moreover, an emergency module is integrated to prioritize special emergency vehicles, reducing their response time during emergencies. To validate the effectiveness of our dynamic traffic signal scheduling system, we conducted simulation experiments using the Simulation of Urban Mobility (SUMO) traffic simulation suite and the SUMO traffic control interface Traci. The results indicate that our system significantly improves intersection throughput and adapts well to various traffic conditions, effectively resolving urban traffic congestion while ensuring fair scheduling plans.
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- 2024
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3. Risk assessment model for international construction projects considering risk interdependence using the DEMATEL method.
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Fengfeng Zhu, Hao Hu, and Feng Xu
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Medicine ,Science - Abstract
Given the complexity of international construction projects (ICP), risk management difficulties commonly cause cost overruns. This paper analyzes the problems of risk interdependence and subjective ratings in the application of the traditional risk assessment model in ICP. To solve the above problems, this paper proposes a risk assessment model for ICP that considers risk interdependence and obtains references from similar projects. The model applies the Decision-Making Trial and Evaluation Laboratory (DEMATEL) to determine the risk interdependence and its contribution to the overall project risk. Moreover, this model recalls the risks, probabilities, impacts, and risk events records of similar historical projects as the necessary inputs, thereby addressing the issue of subjectivity. An integrated framework is provided to identify, analyze, and prioritize ICP risks to incorporate risk interdependence into the risk management process. Finally, this paper demonstrates and validates the proposed model through a real project. The proposed model is useful for international construction companies to support project selection and bidding decisions in the early stage of ICP.
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- 2022
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4. Psychological impact of the COVID-19 epidemic among healthcare workers in paediatric intensive care units in China.
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Yue Zhang, Dan-Dan Pi, Cheng-Jun Liu, Jing Li, and Feng Xu
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Medicine ,Science - Abstract
To perform a mental health evaluation and an early psychological intervention for healthcare workers (HCWs) during the coronavirus disease 2019 (COVID-19) epidemic, an online survey was conducted among 3055 HCWs in the paediatric intensive care units (PICUs) of 62 hospitals in China on March 26, 2020, by the Neurology and Sedation Professional Group, Emergency Department, Paediatrics Branch, Chinese Medical Association. The questionnaire was divided into three parts, including general information, the Impact of Event Scale-Revised (IES-R), and the Depression Anxiety Stress Scale-21 (DASS-21). The results show that a total of 970 HCWs (45.99%) were considered to meet the clinical cut-off scores for posttraumatic stress (PTS), and the proportions of participants with mild to extremely severe symptoms of depression, anxiety and stress were 39.69%, 36.46% and 17.12%, respectively. There was no significant difference in the psychological impact among HCWs of different genders. Married HCWs were 1.48 times more likely to have PTS than unmarried HCWs (95% Cl: 1.20-1.82, p
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- 2022
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5. Effect of blood analysis and immune function on the prognosis of patients with COVID-19.
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Yue-Qiang Fu, Yue-Lin Sun, Si-Wei Lu, Yang Yang, Yi Wang, and Feng Xu
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Medicine ,Science - Abstract
IntroductionThis retrospective study investigated the implications of changes in blood parameters and cellular immune function in patients with Coronavirus Disease 2019 (COVID-19).MethodsRecords were reviewed of 85 patients admitted with COVID-19 between February 4 and 16, 2020. The primary outcome was in-hospital death.ResultsFourteen patients died. The baseline leukocyte count, neutrophil count and hemoglobin was significantly higher in non-survivors compared with survivors, while the reverse was true of lymphocyte count, platelet, PaO2/FiO2, CD3+ count and CD4+ count. The percentage of neutrophil count > 6.3×109/L in death group was significantly higher than that in survival group, and multivariate logistic regression showed neutrophil count > 6.3×109/L was independently associated with mortality. However, there were not significant difference in IgG, IgM, IgA, C3, C4 and the percentage of IgE > 100 IU/ml between the death group and survival group. Areas under the receiver operating characteristic curves of the following at baseline could significantly predict mortality: leukocyte, neutrophil, lymphocyte, CD3+ and CD4+ counts.ConclusionsFor hospitalized patients with COVID-19, lymphocyte, CD3+ and CD4+ counts that marked decrease suggest a poor outcome. Admission neutrophil count > 6.3 ×109/L is independently associated with mortality. At admission, leukocyte, neutrophil, lymphocyte, CD3+ and CD4+ counts should receive added attention.
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- 2020
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6. A web visualization tool using T cell subsets as the predictor to evaluate COVID-19 patient's severity.
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Qibin Liu, Xuemin Fang, Shinichi Tokuno, Ungil Chung, Xianxiang Chen, Xiyong Dai, Xiaoyu Liu, Feng Xu, Bing Wang, and Peng Peng
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Medicine ,Science - Abstract
Wuhan, China was the epicenter of the 2019 coronavirus outbreak. As a designated hospital for COVID-19, Wuhan Pulmonary Hospital has received over 700 COVID-19 patients. With the COVID-19 becoming a pandemic all over the world, we aim to share our epidemiological and clinical findings with the global community. We studied 340 confirmed COVID-19 patients with clear clinical outcomes from Wuhan Pulmonary Hospital, including 310 discharged cases and 30 death cases. We analyzed their demographic, epidemiological, clinical and laboratory data and implemented our findings into an interactive, free access web application to evaluate COVID-19 patient's severity level. Our results show that baseline T cell subsets results differed significantly between the discharged cases and the death cases in Mann Whitney U test: Total T cells (p < 0.001), Helper T cells (p
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- 2020
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7. The association of long-term glycaemic variability versus sustained chronic hyperglycaemia with heart rate-corrected QT interval in patients with type 2 diabetes.
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Jian-Bin Su, Xiao-Hua Yang, Xiu-Lin Zhang, Hong-Li Cai, Hai-Yan Huang, Li-Hua Zhao, Feng Xu, Tong Chen, Xing-Bo Cheng, Xue-Qin Wang, and Yan Lu
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Medicine ,Science - Abstract
Prolonged heart rate-corrected QT(QTc) interval is related to ventricular arrhythmia and cardiovascular mortality, with considerably high prevalence of type 2 diabetes. Additionally, long-term glycaemic variability could be a significant risk factor for diabetic complications in addition to chronic hyperglycaemia. We compared the associations of long-term glycaemic variability versus sustained chronic hyperglycaemia with the QTc interval among type 2 diabetes patients.In this cross-sectional study, 2904 type 2 diabetes patients were recruited who had undergone at least four fasting plasma glucose (FPG) and 2-hour postprandial plasma glucose (PPG) measurements (at least once for every 3 months, respectively) during the preceding year. Long-term glycaemic variabilities of FPG and 2-hour PPG were assessed by their standard deviations (SD-FPG and SD-PPG, respectively), and chronic fasting and postprandial hyperglycaemia were assessed by their means (M-FPG and M-PPG, respectively). HbA1c was also determined upon enrolment to assess current overall glycaemic control. QTc interval was estimated from resting 12-lead electrocardiograms, and more than 440 ms was considered abnormally prolonged.Patients with prolonged QTc interval (≥440 ms) had greater M-FPG, M-PPG, SD-PPG and HbA1c than those with normal QTc interval but comparable SD-FPG. QTc interval was correlated with M-FPG, M-PPG, SD-PPG and HbA1c (r = 0.133, 0.153, 0.245 and 0.207, respectively, p = 0.000) but not with SD-FPG (r = 0.024, p = 0.189). After adjusting for metabolic risk factors via multiple linear regression analysis, SD-PPG, M-PPG and HbA1c (t = 12.16, 2.69 and 10.16, respectively, p = 0.000) were the major independent contributors to the increased QTc interval. The proportion of prolonged QTc interval increased significantly from 10.9% to 14.2% to 26.6% for the first (T1) to second (T2) to third (T3) tertiles of SD-PPG. After adjusting via multiple logistic regression analysis, the odd ratios of prolonged QTc interval of the T2 and T3 versus the T1 of SD-PPG were 1.15 (95% CI, 0.82-1.60) and 2.62 (1.92-3.57), respectively.Increased long-term variability of PPG is a strong independent risk factor for prolonged QTc interval in type 2 diabetes patients, in addition to long-term postprandial hyperglycaemia and current HbA1c.
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- 2017
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8. Overexpression of Rad51 Predicts Poor Prognosis in Colorectal Cancer: Our Experience with 54 Patients.
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Yan Li, Wei-Ya Wang, Jiang-Hong Xiao, Feng Xu, Dian-Ying Liao, Li Xie, Jin Wang, and Feng Luo
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Medicine ,Science - Abstract
BACKGROUND:Aberrant Rad51 expression is implicated in the progression of human malignancies. However, the role of Rad51 in colorectal cancer (CRC) remains undefined. This study aimed to establish a relationship between Rad51 and clinicopathologic features of CRC. METHODS:We retrospectively examined the paraffin-embedded tissue samples obtained from 54 patients with CRC who had received surgical therapies at our institution during 2006-2008. Rad51 expression in adenocarcinoma, paracancerous tissue, and normal colonic tissue was determined by immunohistochemistry. The correlation between Rad51 immunoreactivity and clinicopathologic features of these patients was evaluated. RESULTS:Rad51 immunoreactivity was detected in 67% of adenocarcinoma, 48% of paracancerous tissue, and 27% of normal colonic mucosa. Rad51 expression in adenocarcinoma was significantly higher than normal colonic tissue (p < 0.05). Rad51 was also overexpressed in poorly differentiated tumors and tumor samples from patients with lymph node metastasis (p < 0.05). Patients with Rad51 overexpression had a 69% two-year survival, 49% three-year survival, and 16% five-year survival, considerably worse than patients with negative Rad51 expression (p < 0.05). CONCLUSION:Our data suggest that Rad51 overexpression is correlated with malignant phenotypes of CRC and may predict poor prognosis for these patients.
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- 2017
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9. Regulation of white and brown adipocyte differentiation by RhoGAP DLC1.
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Choon Kiat Sim, Sun-Yee Kim, Reinhard Brunmeir, Qiongyi Zhang, Hongyu Li, Dharmini Dharmasegaran, Carol Leong, Ying Yan Lim, Weiping Han, and Feng Xu
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Medicine ,Science - Abstract
Adipose tissues constitute an important component of metabolism, the dysfunction of which can cause obesity and type II diabetes. Here we show that differentiation of white and brown adipocytes requires Deleted in Liver Cancer 1 (DLC1), a Rho GTPase Activating Protein (RhoGAP) previously studied for its function in liver cancer. We identified Dlc1 as a super-enhancer associated gene in both white and brown adipocytes through analyzing the genome-wide binding profiles of PPARγ, the master regulator of adipogenesis. We further observed that Dlc1 expression increases during differentiation, and knockdown of Dlc1 by siRNA in white adipocytes reduces the formation of lipid droplets and the expression of fat marker genes. Moreover, knockdown of Dlc1 in brown adipocytes reduces expression of brown fat-specific genes and diminishes mitochondrial respiration. Dlc1-/- knockout mouse embryonic fibroblasts show a complete inability to differentiate into adipocytes, but this phenotype can be rescued by inhibitors of Rho-associated kinase (ROCK) and filamentous actin (F-actin), suggesting the involvement of Rho pathway in DLC1-regulated adipocyte differentiation. Furthermore, PPARγ binds to the promoter of Dlc1 gene to regulate its expression during both white and brown adipocyte differentiation. These results identify DLC1 as an activator of white and brown adipocyte differentiation, and provide a molecular link between PPARγ and Rho pathways.
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- 2017
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10. How to reach haze control targets by air pollutants emission reduction in the Beijing-Tianjin-Hebei region of China?
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Feng Xu, Nan Xiang, and Yoshiro Higano
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Medicine ,Science - Abstract
Currently, Haze is one of the greatest environmental problems with serious impacts on human health in China, especially in capital region (Beijing-Tianjin-Hebei region). To alleviate this problem, the Chinese government introduced a National Air Pollution Control Action Plan (NAPCAP) with air pollutants reduction targets by 2017. However, there is doubt whether these targets can be achieved once the plan is implemented. In this work, the effectiveness of NAPCAP is analyzed by developing models of the statistical relationship between PM2.5 concentrations and air pollutant emissions (SO2, NOx, smoke and dust), while taking into account wind and neighboring transfer impacts. The model can also identify ways of calculating the intended emission levels in the Beijing-Tianjin-Hebei area. The results indicate that haze concentration control targets will not be attained by following the NAPCAP, and that the amount of progress needed to meet the targets is unrealistic. A more appropriate approach to reducing air emissions is proposed, which addresses joint regional efforts.
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- 2017
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11. Drug-eluting balloon versus bare-mental stent and drug-eluting stent for de novo coronary artery disease: A systematic review and meta-analysis of 14 randomized controlled trials.
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Kongyong Cui, Shuzheng Lyu, Xiantao Song, Fei Yuan, Feng Xu, Min Zhang, Wei Wang, Dongfeng Zhang, and Jing Dai
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Medicine ,Science - Abstract
BACKGROUND:Drug-eluting balloon (DEB) has become an alternative option to drug-eluting stent (DES) for the treatment of in-stent restenosis (ISR). However, the effect of drug-eluting balloon with regular bare-mental stent (BMS) in de novo coronary artery disease (CAD) is unclear. This meta-analysis aimed to evaluate the efficacy of DEB with regular BMS compared to BMS or DES in de novo CAD. METHODS:Randomized controlled trials (RCTs) assessing the efficacy of DEB+BMS in comparison with BMS or DES were obtained by searching the PubMed, EMBASE, and Cochrane Library databases through January 2016. Primary endpoints were major adverse cardiac events (MACEs) and late lumen loss (LLL). Secondary endpoints included death, myocardial infarction (MI), target lesion revascularization (TLR), stent thrombosis (ST), binary restenosis, and minimum lumen diameter (MLD). Dichotomous and continuous data were presented as odds ratios (ORs) and mean differences (MDs) with 95% confidence intervals (CIs), respectively, and analyzed using a random-effects model. RESULTS:A total of 14 RCTs involving 2281 patients were included in this meta-analysis. DEB+BMS showed significantly less MACEs (OR: 0.67, 95%CI 0.45 to 0.99, P = 0.04) and reduced LLL (MD: -0.30 mm, 95%CI: -0.48 mm to -0.11 mm, P = 0.001) compared with BMS. Meanwhile, treatment with DEB+BMS had disadvantages over DES in terms of MACEs (OR: 1.94, 95%CI 1.24 to 3.05, P = 0.004), LLL (MD: 0.20 mm, 95%CI: 0.07 mm to 0.33 mm, P = 0.003), TLR (OR: 2.53, 95% CI 1.36 to 4.72, P = 0.003), and MLD (MD: -0.25 mm, 95%CI: -0.42 mm to -0.09 mm, P = 0.003). CONCLUSIONS:This limited evidence demonstrated that treatment with DEB+BMS appears to be effective in de novo CAD. In addition, DEB+ BMS clearly showed superiority to BMS, but is inferior to DES in the treatment of patients with de novo CAD. Hence, DES (especially new generation DES) should be recommended for patients with de novo CAD.
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- 2017
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12. Efficacy and Safety of Plastic Wrap for Prevention of Hypothermia after Birth and during NICU in Preterm Infants: A Systematic Review and Meta-Analysis.
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Shaojun Li, Pengfei Guo, Qing Zou, Fuxiang He, Feng Xu, and Liping Tan
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Medicine ,Science - Abstract
OBJECTIVE:This meta-analysis aimed to investigate the efficacy and safety of plastic wrap applied after birth and during NICU in preterm infants for prevention of heat loss in preterm infants. STUDY METHODS:The Medline (1950 to August 2015), the Cochrane Central Register of Controlled Trials (CENTRAL, Issue 7, 2015), CINAHL (1982 to August 2015) and the Embase (1974 to August 2015) databases were searched for randomized controlled trials (RCTs) or quasi-RCTs with main outcomes related to the core temperature (baseline temperature and/or post-stabilization temperature), hypothermia, mortality rate and hyperthermia. RESULT:The included studies were of low to moderate quality. Compared with unwrapped infants, plastic wrap was associated with a significantly higher baseline temperature and post-stabilization temperature both in infants < 28 weeks of gestation (mean difference [MD] = 0.62, 95% CI 0.38 to 0.85; MD = 0.41, 95% CI 0.33 to 0.50, respectively), and in infants between 28 to 34 weeks of gestation (MD = 0.54, 95% CI 0.21 to 0.87; MD = 0.64, 95% CI 0.45 to 0.82, respectively). Use of plastic wrap was associated with lower incidence of hypothermia (relative risk [RR] = 0.70, 95% CI 0.63 to 0.78). However, use of plastic wrap in preterm infants was not associated with decrease in mortality (RR: 0.88, 95% CI 0.70 to 1.12, P = 0.31). Incidence of hyperthermia was significantly higher in the plastic wrap group as compared to that in the control group (RR = 2.55, 95% CI: 1.56 to 4.15, P = 0.0002). Hyperthermia in the plastic wrap group was resolved within one or two hours after unwrapping the babies. CONCLUSION:Plastic wrap can be considered an effective and safe additional intervention to prevent hypothermia in preterm infants. However, its cost-effectiveness and long-term effect on mortality needs to be ascertained by conducting well-designed studies with longer follow-up period.
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- 2016
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13. Serum Amylase Levels in Relation to Islet β Cell Function in Patients with Early Type 2 Diabetes.
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Lei Zhuang, Jian-Bin Su, Xiu-Lin Zhang, Hai-Yan Huang, Li-Hua Zhao, Feng Xu, Tong Chen, Xue-Qin Wang, Gang Wu, and Xiao-Hua Wang
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Medicine ,Science - Abstract
The insulin-pancreatic acinar axis may play a major role in pancreatic function. Amylase is an exocrine enzyme that is produced by pancreatic acinar cells, and low serum amylase levels may be associated with endocrine diseases, such as metabolic syndrome and diabetes. We hypothesized that low serum amylase levels may be associated with impaired islet β cell function in type 2 diabetes. Therefore, we investigated the relationship between the serum amylase levels and islet β cell function in patients with early type 2 diabetes.The cross-sectional study recruited 2327 patients with a mean of 1.71±1.62 years since their diagnosis of type 2 diabetes, and all participants were treated with lifestyle intervention alone. Serum amylase levels, the 75-g oral glucose tolerance test (OGTT) and metabolic risk factors were examined in all participants. The insulin sensitivity index (Matsuda index, ISIMatsuda) and insulin secretion index (ratio of total area-under-the-insulin-curve to glucose-curve, AUCins/glu) were derived from the OGTT. Integrated islet β cell function was assessed by the Insulin Secretion-Sensitivity Index-2 (ISSI-2) (ISIMatsuda multiplied by AUCins/glu).Serum amylase levels in the normal range were significantly correlated with ISIMatsuda, AUCins/glu and ISSI-2 (r = 0.203, 0.246 and 0.413, respectively, p
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- 2016
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14. Glucose Uptake Activities of Bis (2, 3-Dibromo-4, 5-Dihydroxybenzyl) Ether, a Novel Marine Natural Product from Red Alga Odonthaliacorymbifera with Protein Tyrosine Phosphatase 1B Inhibition, In Vitro and In Vivo.
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Feng Xu, Fang Wang, Zhenhong Wang, Wenshan Lv, Wei Wang, and Yangang Wang
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Medicine ,Science - Abstract
BACKGROUND AND AIMS:Protein tyrosine phosphatase 1B (PTP1B) is a novel therapeutic target for type-2 diabetes, which negatively regulates the insulin signaling transduction. Bis (2, 3-dibromo-4, 5-dihydroxybenzyl) ether (BDDE), a novel bromophenol isolated from the Red Alga, is a novel PTP1B inhibitor. But the anti-diabetic effects are not clear. In the present study, we evaluated the in vitro and in vivo antidiabetic effects of BDDE. METHODS:The insulin-resistant HepG2 cells were used to evaluate the in vitro antidiabetic effects of BDDE. MTT assay was used to determine the safety concentrations in HepG2 cells. Glucose assay kit was used to check glucose uptake after treated with BDDE. Western blotting assay was used to explore the potent mechanisms. The db/db mice were used to evaluate the in vivo antidiabetic effects of BDDE. Body weight, blood glucose, Glycated hemoglobin (HbA1c), lipid profile, and insulin level were checked at the respective time points. Gastrocnemii were dissected and used to analyze the PTP1B and insulin receptor β (IRβ) expression. RESULTS:BDDE increased the insulin-resisted glucose uptake in HepG2 cells. BDDE also decreased the expression of PTP1B and activated the substrates and downstream signals in insulin signal pathway, such as IRβ, insulin receptor substrate-1/2 (IRS1/2), phosphoinositide 3-kinase (PI3K), and protein kinase B (PKB/Akt). In the db/db mice model, BDDE significantly decreased the blood glucose, HbA1c and triglyceride (TG) levels. BDDE also decreased the expression of PTP1B and activated the phosphorylation of IRβ in gastrocnemii. Moreover, BDDE at high doses downregulated the body weight without affecting food and water intake. CONCLUSION:Our results suggest that BDDE as a new PTP1B inhibitor improves glucose metabolism by stimulating the insulin signaling and could be used in the treatment of type-2 diabetes mellitus.
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- 2016
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15. An Alternative Strategy for Pan-acetyl-lysine Antibody Generation.
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Sun-Yee Kim, Choon Kiat Sim, Qiongyi Zhang, Hui Tang, Reinhard Brunmeir, Hong Pan, Neerja Karnani, Weiping Han, Kangling Zhang, and Feng Xu
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Medicine ,Science - Abstract
Lysine acetylation is an important post-translational modification in cell signaling. In acetylome studies, a high-quality pan-acetyl-lysine antibody is key to successful enrichment of acetylated peptides for subsequent mass spectrometry analysis. Here we show an alternative method to generate polyclonal pan-acetyl-lysine antibodies using a synthesized random library of acetylated peptides as the antigen. Our antibodies are tested to be specific for acetyl-lysine peptides/proteins via ELISA and dot blot. When pooled, five of our antibodies show broad reactivity to acetyl-lysine peptides, complementing a commercial antibody in terms of peptide coverage. The consensus sequence of peptides bound by our antibody cocktail differs slightly from that of the commercial antibody. Lastly, our antibodies are tested in a proof-of-concept to analyze the acetylome of HEK293 cells. In total we identified 1557 acetylated peptides from 416 proteins. We thus demonstrated that our antibodies are well-qualified for acetylome studies and can complement existing commercial antibodies.
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- 2016
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16. FoxC2 Enhances BMP7-Mediated Anabolism in Nucleus Pulposus Cells of the Intervertebral Disc.
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Zheng Wang, Changfeng Fu, Yong Chen, Feng Xu, Zhenyu Wang, Zhigang Qu, and Yi Liu
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Medicine ,Science - Abstract
Bone-morphogenetic protein-7 (BMP-7) is a growth factor that plays a major role in mediating anabolism and anti-catabolism of the intervertebral disc matrix and cell homeostasis. In osteoblasts, Forkhead box protein C2 (FoxC2) is a downstream target of BMPs and promotes cell proliferation and differentiation. However, the role FoxC2 may play in degenerative human intervertebral disc tissue and the relationship between FoxC2 and BMP-7 in nucleus pulposus (NP) cells remain to be elucidated. This study aims to investigate the presence and signaling mechanisms of FoxC2 in degenerative human intervertebral disc tissue and NP cells. Western blot and real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) analyses were used to measure FoxC2 expression in the NP tissue and cells. Transfections were carried out to measure the effect of FoxC2 on BMP-7-mediated extracellular matrix upregulation. Adenoviral knock-down of Smad1 was performed to investigate the mechanism of BMP-7-induced FoxC2 expression. In degenerative NP tissue, FoxC2 was markedly upregulated and positively correlated with increased disc degeneration. Induction of NP cell proliferation was confirmed by using cell counting kit-8 assay, immunocytochemistry and real-time qRT-PCR for Ki67. FoxC2 led to decreased noggin expression and increased Smad1/5/8 phosphorylation. During combined treatment with BMP-7, FoxC2 greatly potentiated anabolism through synergistic mechanisms on ECM formation. Combination therapy using BMP-7 and FoxC2 may be beneficial to the treatment of intervertebral disc degeneration.
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- 2016
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17. Interleukin 1 Polymorphisms Contribute to Intervertebral Disc Degeneration Risk: A Meta-Analysis.
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Zheng Wang, Zhigang Qu, Changfeng Fu, Feng Xu, Yong Chen, Zhenyu Wang, and Yi Liu
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Medicine ,Science - Abstract
OBJECTIVE:We performed a meta-analysis to assess association between interleukin 1 (IL-1) polymorphisms and the risk of Intervertebral Disc Degeneration (IDD). BACKGROUND:A series of studies have investigated the association between common single nucleotide polymorphisms in IL-1 and IDD risk; however, the overall results are inconclusive. METHODS:Two independent investigators conducted a systematic search for relevant available studies. Allele frequencies were extracted from each study. The association between the IL-1α (+889C/T) or IL-1β (+3954C/T) polymorphism and IDD risk was measured by odds ratios (OR) with 95% confidence intervals (95% CI). RESULTS:Five and six studies, respectively, were ultimately included in the meta-analysis for the IL-1α (+889C/T) and IL-1β (+3954C/T) polymorphism. The combined results showed that the IL-1α (+889C/T) polymorphism was significantly associated with increased susceptibility to IDD, particularly in Caucasians (TT versus CC: OR = 2.95, 95% CI: 1.45, 6.04; Pheterogeneity = 0.82; TT versus CC/CT:OR = 2.29, 95% CI: 1.18, 4.47; Pheterogeneity = 0.20). In contrast, the IL-1β (+3954C/T) polymorphism showed a trend towards increased risk in Caucasians but no association in Asians. CONCLUSION:This meta-analysis suggested that the IL-1α (+889C/T) polymorphism is significantly associated with risk of IDD, especially in Caucasian populations.
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- 2016
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18. SIRT1 Interacts with and Deacetylates ATP6V1B2 in Mature Adipocytes.
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Sun-Yee Kim, Qiongyi Zhang, Reinhard Brunmeir, Weiping Han, and Feng Xu
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Medicine ,Science - Abstract
SIRT1 plays a key role in maintaining metabolic homeostasis in mammals by directly modulating the activities of various transcription factors and metabolic enzymes through lysine deacetylation. White adipose tissue plays a key role in lipid storage and metabolism. To identify novel molecular targets of SIRT1 in fat cells, we used a non-biased proteomic approach. We identified a number of proteins whose acetylation status was significantly affected by SIRT1 modulator treatment in 3T3-L1 adipocytes. Among them, ATP6V1B2, a subunit of the vacuolar (H+)-ATPase, was further shown to be associated with SIRT1 by co-immunoprecipitation assay. Moreover, SIRT1 deacetylates ATP6V1B2 in vitro and in vivo. Taken together, our study demonstrates that ATP6V1B2 is a molecular target of SIRT1 in fat cells and the role of SIRT1 and ATP6V1B2 acetylation in the vacuolar (H+)-ATPase function warrants further investigation.
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- 2015
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19. In situ normoxia enhances survival and proliferation rate of human adipose tissue-derived stromal cells without increasing the risk of tumourigenesis.
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Jane Ru Choi, Belinda Pingguan-Murphy, Wan Abu Bakar Wan Abas, Kar Wey Yong, Chi Tat Poon, Mat Adenan Noor Azmi, Siti Zawiah Omar, Kien Hui Chua, Feng Xu, and Wan Kamarul Zaman Wan Safwani
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Medicine ,Science - Abstract
Adipose tissue-derived stromal cells (ASCs) natively reside in a relatively low-oxygen tension (i.e., hypoxic) microenvironment in human body. Low oxygen tension (i.e., in situ normoxia), has been known to enhance the growth and survival rate of ASCs, which, however, may lead to the risk of tumourigenesis. Here, we investigated the tumourigenic potential of ASCs under their physiological condition to ensure their safe use in regenerative therapy. Human ASCs isolated from subcutaneous fat were cultured in atmospheric O2 concentration (21% O2) or in situ normoxia (2% O2). We found that ASCs retained their surface markers, tri-lineage differentiation potential, and self-renewal properties under in situ normoxia without altering their morphology. In situ normoxia displayed a higher proliferation and viability of ASCs with less DNA damage as compared to atmospheric O2 concentration. Moreover, low oxygen tension significantly up-regulated VEGF and bFGF mRNA expression and protein secretion while reducing the expression level of tumour suppressor genes p16, p21, p53, and pRb. However, there were no significant differences in ASCs telomere length and their relative telomerase activity when cultured at different oxygen concentrations. Collectively, even with high proliferation and survival rate, ASCs have a low tendency of developing tumour under in situ normoxia. These results suggest 2% O2 as an ideal culture condition for expanding ASCs efficiently while maintaining their characteristics.
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- 2015
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20. Purification of Bone Marrow Clonal Cells from Patients with Myelodysplastic Syndrome via IGF-IR.
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Qi He, Chun-Kang Chang, Feng Xu, Qing-Xia Zhang, Wen-Hui Shi, and Xiao Li
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Medicine ,Science - Abstract
Malignant clonal cells purification can greatly benefit basic and clinical studies in myelodysplastic syndrome (MDS). In this study, we investigated the potential of using type 1 insulin-like growth factor receptor (IGF-IR) as a marker for purification of malignant bone marrow clonal cells from patients with MDS. The average percentage of IGF-IR expression in CD34+ bone marrow cells among 15 normal controls was 4.5%, 70% of which also express the erythroid lineage marker CD235a. This indicates that IGF-IR mainly express in erythropoiesis. The expression of IGF-IR in CD34+ cells of 55 MDS patients was significantly higher than that of cells from the normal controls (54.0 vs. 4.5%). Based on the pattern of IGF-IR expression in MDS patients and normal controls, sorting of IGF-IR-positive and removal of CD235a-positive erythroid lineage cells with combination of FISH detection were performed on MDS samples with chromosomal abnormalities. The percentage of malignant clonal cells significantly increased after sorting. The enrichment effect was more significant in clonal cells with a previous percentage lower than 50%. This enrichment effect was present in samples from patients with +8, 5q-/-5, 20q-/-20 or 7q-/-7 chromosomal abnormalities. These data suggest that IGF-IR can be used as a marker for MDS bone marrow clonal cells and using flow cytometry for positive IGF-IR sorting may effectively purify MDS clonal cells.
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- 2015
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21. Bexarotene reduces blood-brain barrier permeability in cerebral ischemia-reperfusion injured rats.
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Lu Xu, Fang Cao, Feng Xu, Baicheng He, and Zhi Dong
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Medicine ,Science - Abstract
Matrix metalloproteinase-9 (MMP-9) over-expression disrupts the blood-brain barrier (BBB) in the ischemic brain. The retinoid X receptor agonist bexarotene suppresses MMP-9 expression in endothelial cells and displays neuroprotective effects. Therefore, we hypothesized that bexarotene may have a beneficial effect on I/R-induced BBB dysfunction.A total of 180 rats were randomized into three groups (n = 60 each): (i) a sham-operation group, (ii) a cerebral ischemia-reperfusion (I/R) group, and (iii) an I/R+bexarotene group. Brain water content was measured by the dry wet weight method. BBB permeability was analyzed by Evans Blue staining and the magnetic resonance imaging contrast agent Omniscan. MMP-9 mRNA expression, protein expression, and activity were assessed by reverse transcription polymerase chain reaction, Western blotting, and gelatin zymography, respectively. Apolipoprotein E (apoE), claudin-5, and occludin expression were analyzed by Western blotting.After 24 h, 48 h, and 72 h post-I/R, several effects were observed with bexarotene administration: (i) brain water content and BBB permeability were significantly reduced; (ii) MMP-9 mRNA and protein expression as well as activity were significantly decreased; (iii) claudin-5 and occludin expression were significantly increased; and (iv) apoE expression was significantly increased.Bexarotene decreases BBB permeability in rats with cerebral I/R injury. This effect may be due in part to bexarotene's upregulation of apoE expression, which has been previously shown to reduce BBB permeability through suppressing MMP-9-mediated degradation of the tight junction proteins claudin-5 and occludin. This work offers insight to aid future development of therapeutic agents for cerebral I/R injury in human patients.
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- 2015
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22. Combined Salvianolic Acid B and Ginsenoside Rg1 Exerts Cardioprotection against Ischemia/Reperfusion Injury in Rats.
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Yanping Deng, Min Yang, Feng Xu, Qian Zhang, Qun Zhao, Haitao Yu, Defang Li, Ge Zhang, Aiping Lu, Kenka Cho, Fukang Teng, Peng Wu, Linlin Wang, Wanying Wu, Xuan Liu, De-An Guo, and Baohong Jiang
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Medicine ,Science - Abstract
Lack of pharmacological strategies in clinics restricts the patient prognosis with myocardial ischemia/reperfusion (I/R) injury. The aim of this study was to evaluate the cardioprotection of combined salvianolic acid B (SalB) and ginsenoside Rg1 (Rg1) against myocardial I/R injury and further investigate the underlying mechanism. I/R injury was induced by coronary artery ligation for Wistar male rats and hypoxia/reoxygenation injury was induced on H9c2 cells. Firstly, the best ratio between SalB and Rg1was set as 2:5 based on their effects on heart function detected by hemodynamic measurement. Then SalB-Rg1 (2:5) was found to maintain mitochondrial membrane potential and resist apoptosis and necrosis in H9c2 cell with hypoxia/reoxygenation injury. Companying with same dose of SalB or Rg1 only, SalB-Rg1 showed more significant effects on down-regulation of myocardial infarct size, maintenance of myocardium structure, improvement on cardiac function, decrease of cytokine secretion including TNF-α, IL-1β, RANTES and sVCAM-1. Finally, the SalB-Rg1 improved the viability of cardiac myocytes other than cardiac fibroblasts in rats with I/R injury using flow cytometry. Our results revealed that SalB-Rg1 was a promising strategy to prevent myocardial I/R injury.
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- 2015
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23. The Regulation of Lipid Deposition by Insulin in Goose Liver Cells Is Mediated by the PI3K-AKT-mTOR Signaling Pathway.
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Chunchun Han, Shouhai Wei, Fang He, Dandan Liu, Huofu Wan, Hehe Liu, Liang Li, Hongyong Xu, Xiaohui Du, and Feng Xu
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Medicine ,Science - Abstract
We previously showed that the fatty liver formations observed in overfed geese are accompanied by the activation of the PI3K-Akt-mTOR pathway and an increase in plasma insulin concentrations. Recent studies have suggested a crucial role for the PI3K-Akt-mTOR pathway in regulating lipid metabolism; therefore, we hypothesized that insulin affects goose hepatocellular lipid metabolism through the PI3K-Akt-mTOR signaling pathway.Goose primary hepatocytes were isolated and treated with serum-free media supplemented with PI3K-Akt-mTOR pathway inhibitors (LY294002, rapamycin, and NVP-BEZ235, respectively) and 50 or 150 nmol/L insulin.Insulin induced strong effects on lipid accumulation as well as the mRNA and protein levels of genes involved in lipogenesis, fatty acid oxidation, and VLDL-TG assembly and secretion in primary goose hepatocytes. The stimulatory effect of insulin on lipogenesis was significantly decreased by treatment with PI3K-Akt-mTOR inhibitors. These inhibitors also rescued the insulin-induced down-regulation of fatty acid oxidation and VLDL-TG assembly and secretion.These findings suggest that the stimulatory effect of insulin on lipid deposition is mediated by PI3K-Akt-mTOR regulation of lipogenesis, fatty acid oxidation, and VLDL-TG assembly and secretion in goose hepatocytes.
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- 2015
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24. Acetylome Analysis Identifies SIRT1 Targets in mRNA-Processing and Chromatin-Remodeling in Mouse Liver.
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Sun-Yee Kim, Choon Kiat Sim, Hui Tang, Weiping Han, Kangling Zhang, and Feng Xu
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Medicine ,Science - Abstract
Lysine acetylation is a post-translational modification found on numerous proteins, a strategy used in cell signaling to change protein activity in response to internal or external cues. Sirtuin 1 (SIRT1) is a central lysine deacetylase involved in a variety of cellular processes including metabolism, apoptosis, and DNA repair. Here we characterize the lysine acetylome in mouse liver, and by using a model of Sirt1-/-knockout mouse, show that SIRT1 regulates the deacetylation of 70 proteins in the liver in-vivo. Amongst these SIRT1-regulated proteins, we find that four RNA-processing proteins and a chromatin-remodeling protein can be deacetylated by SIRT1 directly in-vitro. The discovery that SIRT1 has a potential role in RNA-processing suggests a new layer of regulation in the variety of functions performed by SIRT1.
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- 2015
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25. Distinct clinical and experimental characteristics in the patients younger than 60 years old with myelodysplastic syndromes.
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Xiao Li, Zhi-jian Xiao, Chun-kang Chang, Feng Xu, Ling-yun Wu, Qi He, Ze-feng Xu, Lu-xi Song, Zheng Zhang, Li-yu Zhou, Ji-ying Su, Xi Zhang, and Juan Guo
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Medicine ,Science - Abstract
Myelodysplastic syndromes (MDS) mainly occur in elderly individuals in Western countries. However, MDS is commonly found in young individuals (
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- 2013
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26. Preparation and characterization of electrospun PLCL/Poloxamer nanofibers and dextran/gelatin hydrogels for skin tissue engineering.
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Jian-feng Pan, Ning-hua Liu, Hui Sun, and Feng Xu
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Medicine ,Science - Abstract
In this study, two different biomaterials were fabricated and their potential use as a bilayer scaffold for skin tissue engineering applications was assessed. The upper layer biomaterial was a Poly(ε-caprolactone-co-lactide)/Poloxamer (PLCL/Poloxamer) nanofiber membrane fabricated using electrospinning technology. The PLCL/Poloxamer nanofibers (PLCL/Poloxamer, 9/1) exhibited strong mechanical properties (stress/strain values of 9.37 ± 0.38 MPa/187.43 ± 10.66%) and good biocompatibility to support adipose-derived stem cells proliferation. The lower layer biomaterial was a hydrogel composed of 10% dextran and 20% gelatin without the addition of a chemical crosslinking agent. The 5/5 dextran/gelatin hydrogel displayed high swelling property, good compressive strength, capacity to present more than 3 weeks and was able to support cells proliferation. A bilayer scaffold was fabricated using these two materials by underlaying the nanofibers and casting hydrogel to mimic the structure and biological function of native skin tissue. The upper layer membrane provided mechanical support in the scaffold and the lower layer hydrogel provided adequate space to allow cells to proliferate and generate extracellular matrix. The biocompatibility of bilayer scaffold was preliminarily investigated to assess the potential cytotoxicity. The results show that cell viability had not been affected when cocultured with bilayer scaffold. As a consequence, the bilayer scaffold composed of PLCL/Poloxamer nanofibers and dextran/gelatin hydrogels is biocompatible and possesses its potentially high application prospect in the field of skin tissue engineering.
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- 2014
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27. An updated meta-analysis of randomized controlled trials assessing the effect of sorafenib in advanced hepatocellular carcinoma.
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Songlin Peng, Yang Zhao, Feng Xu, Changjun Jia, Yongqing Xu, and Chaoliu Dai
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Medicine ,Science - Abstract
BACKGROUND: The efficacy of sorafenib in the treatment of advanced hepatocellular carcinoma (HCC) remains controversial. Therefore, we conducted a meta-analysis to evaluate the efficacy and safety of sorafenib for treating patients with advanced HCC. METHODS: The PubMed, Embase, and Web of Science databases were searched. Eligible studies were randomized controlled trials (RCTs) that assessed sorafenib therapy in patients with advanced HCC. The outcomes included overall survival (OS), time to progression (TTP), overall response rate (ORR), and toxicities. Hazard ratio (HR) and risk ratio (RR) were used for the meta-analysis and were expressed with 95% confidence intervals (CIs). RESULTS: Seven RCTs, with a total of 3807 patients, were included in this meta-analysis. All patients received sorafenib alone, or with other chemotherapeutic regimens. Pooled estimates showed that sorafenib improved the OS (HR = 0.74, 95% CI: 0.61, 0.90; P = 0.002), or TTP outcomes (HR = 0.69, 95% CI: 0.55, 0.86; P = 0.001). Subgroup analysis revealed that sorafenib was more effective in the patients with an Eastern Cooperative Oncology Group performance status (ECOG PS) of 1-2 (HR = 0.77, 95% CI: 0.60, 1.0; P = 0.05), or macroscopic vascular invasion (MVI), and/or extrahepatic spread (EHS) (H = 0.65, 95% CI: 0.46, 0.93; P = 0.02), in terms of OS. Patients who received sorafenib did not have a higher ORR (RR = 0.85, 95% CI: 0.65, 1.11; P = 0.10). In addition, there was a slight increase in toxicity in the sorafenib group. CONCLUSION: Treatment with sorafenib significantly improved OS and TTP in patients with advanced HCC. Additional large-scale, well-designed RCTs are needed to evaluate the efficacy of sorafenib-based therapy in the treatment of advanced HCC.
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- 2014
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28. Decitabine of reduced dosage in Chinese patients with myelodysplastic syndrome: a retrospective analysis.
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Xiao Li, Qiang Song, Yu Chen, Chunkang Chang, Dong Wu, Lingyun Wu, Jiying Su, Xi Zhang, Liyu Zhou, Luxi Song, Zheng Zhang, Feng Xu, and Ming Hou
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Medicine ,Science - Abstract
Decitabine has been approved for the treatment of all subtypes of myelodysplastic syndrome (MDS). However, the optimal regimen for decitabine treatment is not well established. In this study, an observational, retrospective and multi-center analysis was performed to explore the decitabine schedule for the treatment of MDS. A total of 79 patients received reduced dosage decitabine treatment (15 mg/M2/day intravenously for five consecutive days every four weeks). Fifty-three out of the 79 patients were defined as intermediate-2/high risk by international prognostic scoring system (IPSS) risk category. 67.1% of MDS patients achieved treatment response including complete response (CR) (n = 23), Partial response (n = 1), marrow CR (mCR) with hematological improvement (HI) (n = 11), mCR without HI (n = 11) and HI alone (n = 7) with a median of 4 courses (range 1-11). The median overall survival (OS) was 18.0 months. The median OS was 22.0, 17.0 and 12.0 months in the patients with CR, those with other response, and those without response, respectively. In addition, this regimen contributed to zero therapy-related death and punctual course delivery, although III or IV grade of cytopenia was frequently observed. In conclusion, the 15 mg/M2/d×5 day decitabine regimen was effective and safe for Chinese MDS patients with IPSS score of 0.5 or higher.
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- 2014
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29. Fever burden is an independent predictor for prognosis of traumatic brain injury.
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Long Bao, Du Chen, Li Ding, Weihua Ling, and Feng Xu
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Medicine ,Science - Abstract
To evaluate fever burden as an independent predictor for prognosis of traumatic brain injury (TBI).This retrospective study involved 355 TBI patients with Glasgow Coma Scale (GCS) ≤14, who presented at the emergency department of our hospital between November 2010 and October 2012. At 6 months follow-up, patients were divided into 5 groups based on Glasgow Outcome Scale (GOS) and dichotomized to GOS score (high (4 to 5) vs. low (1 to 3)). The relationship between fever burden and GOS was assessed.Fever burden increased as GOS scores decreased from 5 to 2, except for score 1 of GOS, which corresponded to a significant lower fever burden. Following dichotomization, patients in the high GOS group were younger, and showed less abnormal pupil reactivity (P
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- 2014
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30. Serum albumin and prealbumin predict the poor outcome of traumatic brain injury.
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Du Chen, Long Bao, Shi-qi Lu, and Feng Xu
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Medicine ,Science - Abstract
BACKGROUND: Serum albumin and prealbumin are both negative acute-phase reactants, and usually at low levels in stress. We aim to determine their predictive values for poor outcome of traumatic brain injury (TBI). METHODS: A total of 326 patients of TBI were enrolled and followed-up by telephone 6 months after discharge. They were divided into a favorable group (GOS: 3 to 5) and an unfavorable group (GOS: 1 to 2). Serum albumin and prealbumin were measured from vein blood within 24 h after admission. RESULTS: Ninety one (27.9%) patients were with poor outcome (GOS: 1 to 2). The unfavorable group had lower albumin and prealbumin (P
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- 2014
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31. A survey of overlooked viral infections in biological experiment systems.
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Yajing Wang, Hui Wang, Kunhan Xu, Peixiang Ni, Huan Zhang, Jinmin Ma, Huanming Yang, and Feng Xu
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Medicine ,Science - Abstract
It is commonly accepted that there are many unknown viruses on the planet. For the known viruses, do we know their prevalence, even in our experimental systems? Here we report a virus survey using recently published small (s)RNA sequencing datasets. The sRNA reads were assembled and contigs were screened for virus homologues against the NCBI nucleotide (nt) database using the BLASTn program. To our surprise, approximately 30% (28 out of 94) of publications had highly scored viral sequences in their datasets. Among them, only two publications reported virus infections. Though viral vectors were used in some of the publications, virus sequences without any identifiable source appeared in more than 20 publications. By determining the distributions of viral reads and the antiviral RNA interference (RNAi) pathways using the sRNA profiles, we showed evidence that many of the viruses identified were indeed infecting and generated host RNAi responses. As virus infections affect many aspects of host molecular biology and metabolism, the presence and impact of viruses needs to be actively investigated in experimental systems.
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- 2014
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32. Culprit vessel only versus multivessel percutaneous coronary intervention in patients presenting with ST-segment elevation myocardial infarction and multivessel disease.
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Dongfeng Zhang, Xiantao Song, Shuzheng Lv, Fei Yuan, Feng Xu, Min Zhang, Wei Li, and Shuai Yan
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Medicine ,Science - Abstract
BACKGROUND: The best strategy for ST-segment elevation myocardial infarction (STEMI) patients with multivessel disease (MVD), who underwent primary percutaneous coronary intervention (PCI) in the acute phase, is not well established. OBJECTIVES: Our goal was to conduct a meta-analysis comparing culprit vessel only percutaneous coronary intervention (culprit PCI) with multivessel percutaneous coronary intervention (MV-PCI) for treatment of patients with STEMI and MVD. METHODS: Pubmed, Elsevier, Embase, and China National Knowledge Infrastructure (CNKI) databases were systematically searched for randomized and nonrandomized studies comparing culprit PCI and MV-PCI strategies during the index procedure. A meta-analysis was performed using Review Manager 5.1 (Cochrane Center, Denmark). RESULTS: Four randomized and fourteen nonrandomized studies involving 39,390 patients were included. MV-PCI strategy is associated with an increased short-term mortality (OR: 0.50, 95% CI: 0.32 to 0.77, p = 0.002), long-term mortality (OR: 0.52, 95% CI: 0.36 to 0.74, p
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- 2014
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33. Establishment and validation of an updated diagnostic FCM scoring system based on pooled immunophenotyping in CD34+ blasts and its clinical significance for myelodysplastic syndromes.
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Feng Xu, Xiao Li, Chun-Kang Chang, Juan Guo, Ling-Yun Wu, Qi He, Zheng Zhang, Yang Zhu, Shu-Chen Gu, Wen-Hui Shi, Lu-Xi Song, Ji-Ying Su, Li-Yu Zhou, Xi Zhang, and Dong Wu
- Subjects
Medicine ,Science - Abstract
Abnormal immunophenotypes of hematopoietic cells can be detected by flow cytometry (FCM) to assist the diagnosis of myelodysplastic syndromes (MDS). We previously established a FCM scoring system for the diagnosis of low-grade MDS. In this study, additional valuable antigens were involved in an updated FCM scoring system (u-FCMSS) for all MDS subtypes. The u-FCMSS showed better sensitivity and specificity (89.4% and 96.5%) in distinguishing MDS from non-clonal cytopenia diseases. Validation analysis of u-FCMSS exhibited comparable sensitivity and specificity (86.7% and 93.3%) and high agreement rate (88.9%) of FCM diagnosis with morphological diagnosis at optimal cut-off (score 3). The distribution of FCM scores in different disease stages was also analyzed. The results suggested that early scoring from abnormal expression of mature myeloid/lymphoid antigens and advanced scoring from abnormal expression of stem/progenitor antigens expression constituted the majority of FCM scores of low-grade and high-grade MDS, respectively. High early scoring was generally accompanied by low IPSS-R score and superior survival, whereas high advanced scoring was accompanied by high IPSS-R score and inferior survival. In addition, the low-risk MDS patients with high early scoring and low advanced scoring were revealed as candidates for immunosuppressive therapy, whereas those with high advanced scoring and low early scoring may be more suitable for decitabine treatment. In conclusion, the u-FCMSS is a useful tool for diagnosis, prognosis and treatment selection in MDS. Differences in classes of antigens expressed and in distribution of FCM scores may reflect distinctive stage characteristics of MDS during disease progression.
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- 2014
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34. Peroxisome proliferator-activated receptor-γ agonist 15d-prostaglandin J2 mediates neuronal autophagy after cerebral ischemia-reperfusion injury.
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Feng Xu, Jian Li, Wei Ni, Yi-wen Shen, and Xiao-ping Zhang
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Medicine ,Science - Abstract
Peroxisome proliferator-activated receptor-γ (PPAR-γ) has recently emerged as potential therapeutic agents for cerebral ischemia-reperfusion (I/R) injury because of anti-neuronal apoptotic actions. However, whether PPAR-γ activation mediates neuronal autophagy in such conditions remains unclear. Therefore, in this study, we investigated the role of PPAR-γ agonist 15-PGJ(2) on neuronal autophagy induced by I/R. The expression of autophagic-related protein in ischemic cortex such as LC3-II, Beclin 1, cathepsin-B and LAMP1 increased significantly after cerebral I/R injury. Furthermore, increased punctate LC3 labeling and cathepsin-B staining occurred in neurons. Treatment with PPAR-γ agonist 15d-PGJ(2) decreased not only autophagic-related protein expression in ischemic cortex, but also immunoreactivity of LC3 and cathepsin-B in neurons. Autophagic inhibitor 3-methyladenine (3-MA) decreased LC3-II levels, reduced the infarct volume, and mimicked some protective effect of 15d-PGJ(2) against cerebral I/R injury. These results indicate that PPAR-γ agonist 15d-PGJ(2) exerts neuroprotection by inhibiting neuronal autophagy after cerebral I/R injury. Although the molecular mechanisms underlying PPAR-γ agonist in mediating neuronal autophagy remain to be determined, neuronal autophagy may be a new target for PPAR-γ agonist treatment in cerebral I/R injury.
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- 2013
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35. Quantitative design of regulatory elements based on high-precision strength prediction using artificial neural network.
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Hailin Meng, Jianfeng Wang, Zhiqiang Xiong, Feng Xu, Guoping Zhao, and Yong Wang
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Medicine ,Science - Abstract
Accurate and controllable regulatory elements such as promoters and ribosome binding sites (RBSs) are indispensable tools to quantitatively regulate gene expression for rational pathway engineering. Therefore, de novo designing regulatory elements is brought back to the forefront of synthetic biology research. Here we developed a quantitative design method for regulatory elements based on strength prediction using artificial neural network (ANN). One hundred mutated Trc promoter & RBS sequences, which were finely characterized with a strength distribution from 0 to 3.559 (relative to the strength of the original sequence which was defined as 1), were used for model training and test. A precise strength prediction model, NET90_19_576, was finally constructed with high regression correlation coefficients of 0.98 for both model training and test. Sixteen artificial elements were in silico designed using this model. All of them were proved to have good consistency between the measured strength and our desired strength. The functional reliability of the designed elements was validated in two different genetic contexts. The designed parts were successfully utilized to improve the expression of BmK1 peptide toxin and fine-tune deoxy-xylulose phosphate pathway in Escherichia coli. Our results demonstrate that the methodology based on ANN model can de novo and quantitatively design regulatory elements with desired strengths, which are of great importance for synthetic biology applications.
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- 2013
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36. Inference of gene-phenotype associations via protein-protein interaction and orthology.
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Panwen Wang, Wing-Fu Lai, Mulin Jun Li, Feng Xu, Hari Krishna Yalamanchili, Robin Lovell-Badge, and Junwen Wang
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Medicine ,Science - Abstract
One of the fundamental goals of genetics is to understand gene functions and their associated phenotypes. To achieve this goal, in this study we developed a computational algorithm that uses orthology and protein-protein interaction information to infer gene-phenotype associations for multiple species. Furthermore, we developed a web server that provides genome-wide phenotype inference for six species: fly, human, mouse, worm, yeast, and zebrafish. We evaluated our inference method by comparing the inferred results with known gene-phenotype associations. The high Area Under the Curve values suggest a significant performance of our method. By applying our method to two human representative diseases, Type 2 Diabetes and Breast Cancer, we demonstrated that our method is able to identify related Gene Ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways. The web server can be used to infer functions and putative phenotypes of a gene along with the candidate genes of a phenotype, and thus aids in disease candidate gene discovery. Our web server is available at http://jjwanglab.org/PhenoPPIOrth.
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- 2013
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37. Bevacizumab attenuates hepatic fibrosis in rats by inhibiting activation of hepatic stellate cells.
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Yangqing Huang, Helin Feng, Tong Kan, Bin Huang, Minfeng Zhang, Yesheng Li, Changying Shi, Mengchao Wu, Yunquan Luo, Jiamei Yang, and Feng Xu
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Medicine ,Science - Abstract
Angiogenesis is a fundamental part of the response to tissue injury, which is involved in the development of hepatic fibrosis. Vascular endothelial growth factor plays an important role in angiogenesis. The expression of VEGF is increased during hepatic fibrogenesis and correlates with the micro-vessel density. In this study, we investigated the effects of bevacizumab, an anti-angiogenetic drug, on the formation of hepatic fibrosis. We found that bevacizumab could attenuate the development of hepatic fibrosis and contribute to the protection of liver function. Bevacizumab was also found to downregulate the expression α-SMA and TGF-β1, which have been reported to be profibrogenic genes in vivo. We also observed that the expression of VEGF increased significantly during the development of hepatic fibrosis and CCl4 was found to induce hepatocytes to secrete VEGF, which led to the activation and proliferation of HSCs. Bevacizumab was also found to block the effects of the hepatocytes on the activation and proliferation of HSCs. Our results suggest that bevacizumab might alleviate liver fibrosis by blocking the effect of VEGF on HSCs. Bevacizumab might be suitable as a potential agent for hepatic fibrosis therapy.
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- 2013
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38. Salvianolic acid A, a novel matrix metalloproteinase-9 inhibitor, prevents cardiac remodeling in spontaneously hypertensive rats.
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Baohong Jiang, Defang Li, Yanping Deng, Fukang Teng, Jing Chen, Song Xue, Xiangqian Kong, Cheng Luo, Xu Shen, Hualiang Jiang, Feng Xu, Wengang Yang, Jun Yin, Yanhui Wang, Hui Chen, Wanying Wu, Xuan Liu, and De-an Guo
- Subjects
Medicine ,Science - Abstract
Cardiac fibrosis is a deleterious consequence of hypertension which may further advance to heart failure and increased matrix metalloproteinase-9 (MMP-9) contributes to the underlying mechanism. Therefore, new therapeutic strategies to attenuate the effects of MMP-9 are urgently needed. In the present study, we characterize salvianolic acid A (SalA) as a novel MMP-9 inhibitor at molecular, cellular and animal level. We expressed a truncated form of MMP-9 which contains only the catalytic domain (MMP-9 CD), and used this active protein for enzymatic kinetic analysis and Biacore detection. Data generated from these assays indicated that SalA functioned as the strongest competitive inhibitor of MMP-9 among 7 phenolic acids from Salvia miltiorrhiza. In neonatal cardiac fibroblast, SalA inhibited fibroblast migration, blocked myofibroblast transformation, inhibited secretion of intercellular adhesion molecule (ICAM), interleukin-6 (IL-6) and soluble vascular cell adhesion molecule-1 (sVCAM-1) as well as collagen induced by MMP-9 CD. Functional effects of SalA inhibition on MMP-9 was further confirmed in cultured cardiac H9c2 cell overexpressing MMP-9 in vitro and in heart of spontaneously hypertensive rats (SHR) in vivo. Moreover, SalA treatment in SHR resulted in decreased heart fibrosis and attenuated heart hypertrophy. These results indicated that SalA is a novel inhibitor of MMP-9, thus playing an inhibitory role in hypertensive fibrosis. Further studies to develop SalA and its analogues for their potential clinical application of cardioprotection are warranted.
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- 2013
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39. Epidermal growth factor receptor (EGFR)-RAS signaling pathway in penile squamous cell carcinoma.
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Hong-Feng Gou, Xiang Li, Meng Qiu, Ke Cheng, Long-Hao Li, Hang Dong, Ye Chen, Yuan Tang, Feng Gao, Feng Zhao, Hai-Tao Men, Jun Ge, Jing-Mei Su, Feng Xu, Feng Bi, Jian-Jun Gao, and Ji-Yan Liu
- Subjects
Medicine ,Science - Abstract
Penile Squamous Cell Carcinoma (SCC) is a rare cancer with poor prognosis and limited response to conventional chemotherapy. The genetic and epigenetic alterations of Epidermal Growth Factor Receptor (EGFR)-RAS-RAF signaling in penile SCC are unclear. This study aims to investigate four key members of this pathway in penile SCC. We examined the expression of EGFR and RAS-association domain family 1 A (RASSF1A) as well as the mutation status of K-RAS and BRAF in 150 cases of penile SCC. EGFR and RASSF1A expression was evaluated by immunohistochemistry. KRAS mutations at codons 12 and 13, and the BRAF mutation at codon 600 were analyzed on DNA isolated from formalin fixed paraffin embedded tissues by direct genomic sequencing. EGFR expression was positive in all specimens, and its over-expression rate was 92%. RASSF1A expression rate was only 3.42%. Significant correlation was not found between the expression of EGFR or RASSF1A and tumor grade, pT stage or lymph node metastases. The detection of KRAS and BRAF mutations analysis was performed in 94 and 83 tumor tissues, respectively. We found KRAS mutation in only one sample and found no BRAF V600E point mutation. In summary, we found over-expression of EGFR in the majority cases of penile SCC, but only rare expression of RASSF1A, rare KRAS mutation, and no BRAF mutation in penile SCC. These data suggest that anti-EGFR agents may be potentially considered as therapeutic options in penile SCC.
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- 2013
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40. Enhancement of Cerenkov luminescence imaging by dual excitation of Er(3+),Yb(3+)-doped rare-earth microparticles.
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Xiaowei Ma, Fei Kang, Feng Xu, Ailing Feng, Ying Zhao, Tianjian Lu, Weidong Yang, Zhe Wang, Min Lin, and Jing Wang
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Medicine ,Science - Abstract
UNLABELLED:Cerenkov luminescence imaging (CLI) has been successfully utilized in various fields of preclinical studies; however, CLI is challenging due to its weak luminescent intensity and insufficient penetration capability. Here, we report the design and synthesis of a type of rare-earth microparticles (REMPs), which can be dually excited by Cerenkov luminescence (CL) resulting from the decay of radionuclides to enhance CLI in terms of intensity and penetration. METHODS:Yb(3+)- and Er(3+)- codoped hexagonal NaYF4 hollow microtubes were synthesized via a hydrothermal route. The phase, morphology, and emission spectrum were confirmed for these REMPs by power X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectrophotometry, respectively. A commercial CCD camera equipped with a series of optical filters was employed to quantify the intensity and spectrum of CLI from radionuclides. The enhancement of penetration was investigated by imaging studies of nylon phantoms and nude mouse pseudotumor models. RESULTS:the REMPs could be dually excited by CL at the wavelengths of 520 and 980 nm, and the emission peaks overlaid at 660 nm. This strategy approximately doubled the overall detectable intensity of CLI and extended its maximum penetration in nylon phantoms from 5 to 15 mm. The penetration study in living animals yielded similar results. CONCLUSIONS:this study demonstrated that CL can dually excite REMPs and that the overlaid emissions in the range of 660 nm could significantly enhance the penetration and intensity of CL. The proposed enhanced CLI strategy may have promising applications in the future.
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- 2013
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41. Correlative nanoscale 3D imaging of structure and composition in extended objects.
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Feng Xu, Lukas Helfen, Heikki Suhonen, Dan Elgrabli, Sam Bayat, Péter Reischig, Tilo Baumbach, and Peter Cloetens
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Medicine ,Science - Abstract
Structure and composition at the nanoscale determine the behavior of biological systems and engineered materials. The drive to understand and control this behavior has placed strong demands on developing methods for high resolution imaging. In general, the improvement of three-dimensional (3D) resolution is accomplished by tightening constraints: reduced manageable specimen sizes, decreasing analyzable volumes, degrading contrasts, and increasing sample preparation efforts. Aiming to overcome these limitations, we present a non-destructive and multiple-contrast imaging technique, using principles of X-ray laminography, thus generalizing tomography towards laterally extended objects. We retain advantages that are usually restricted to 2D microscopic imaging, such as scanning of large areas and subsequent zooming-in towards a region of interest at the highest possible resolution. Our technique permits correlating the 3D structure and the elemental distribution yielding a high sensitivity to variations of the electron density via coherent imaging and to local trace element quantification through X-ray fluorescence. We demonstrate the method by imaging a lithographic nanostructure and an aluminum alloy. Analyzing a biological system, we visualize in lung tissue the subcellular response to toxic stress after exposure to nanotubes. We show that most of the nanotubes are trapped inside alveolar macrophages, while a small portion of the nanotubes has crossed the barrier to the cellular space of the alveolar wall. In general, our method is non-destructive and can be combined with different sample environmental or loading conditions. We therefore anticipate that correlative X-ray nano-laminography will enable a variety of in situ and in operando 3D studies.
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- 2012
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42. Poly I:C enhances susceptibility to secondary pulmonary infections by gram-positive bacteria.
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Xiaoli Tian, Feng Xu, Wing Yi Lung, Cherise Meyerson, Amir Ali Ghaffari, Genhong Cheng, and Jane C Deng
- Subjects
Medicine ,Science - Abstract
Secondary bacterial pneumonias are a frequent complication of influenza and other respiratory viral infections, but the mechanisms underlying viral-induced susceptibility to bacterial infections are poorly understood. In particular, it is unclear whether the host's response against the viral infection, independent of the injury caused by the virus, results in impairment of antibacterial host defense. Here, we sought to determine whether the induction of an "antiviral" immune state using various viral recognition receptor ligands was sufficient to result in decreased ability to combat common bacterial pathogens of the lung. Using a mouse model, animals were administered polyinosine-polycytidylic acid (poly I:C) or Toll-like 7 ligand (imiquimod or gardiquimod) intranasally, followed by intratracheal challenge with Streptococcus pneumoniae. We found that animals pre-exposed to poly I:C displayed impaired bacterial clearance and increased mortality. Poly I:C-exposed animals also had decreased ability to clear methicillin-resistant Staphylococcus aureus. Furthermore, we showed that activation of Toll-like receptor (TLR)3 and Retinoic acid inducible gene (RIG-I)/Cardif pathways, which recognize viral nucleic acids in the form of dsRNA, both contribute to poly I:C mediated impairment of bacterial clearance. Finally, we determined that poly I:C administration resulted in significant induction of type I interferons (IFNs), whereas the elimination of type I IFN signaling improved clearance and survival following secondary bacterial pneumonia. Collectively, these results indicate that in the lung, poly I:C administration is sufficient to impair pulmonary host defense against clinically important gram-positive bacterial pathogens, which appears to be mediated by type I IFNs.
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- 2012
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43. Prevalence of childhood atopic dermatitis: an urban and rural community-based study in Shanghai, China.
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Feng Xu, Shuxian Yan, Fei Li, Minqiang Cai, Weihan Chai, Minmin Wu, Chaowei Fu, Zhuohui Zhao, Haidong Kan, Kefei Kang, and Jinhua Xu
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Medicine ,Science - Abstract
BACKGROUND: Atopic dermatitis (AD) is a common inflammatory and chronically relapsing disorder with increasing prevalence. However, little is known about its prevalence in Shanghai, the top metropolitan of China. This study will estimate and compare the prevalence of AD in urban and rural areas in representative samples of 3 to 6-year-old children in Shanghai. METHODOLOGY/PRINCIPAL FINDINGS: A descriptive cross-sectional study was performed. Pre-school children were obtained by cluster sampling from 8 communities in different districts in Shanghai. The main instrument was the core questionnaire module for AD used in the U.K. Working Party's study. All the data were statistically analyzed by EpiData 3.1 and SPSS16.0. A total of 10,436 children completed the study satisfactorily, with a response rate of 95.8%. The prevalence of AD in 3 to 6-year-old children was 8.3% (Male: 8.5%, Female: 8.2%). The prevalence in urban areas of Shanghai was gradiently and significantly higher than that in rural areas. The highest prevalence was in the core urban area (10.2% in Xuhui Tianping) vs. the lowest far from the urban areas (4.6% in Chongming Baozhen). CONCLUSIONS/SIGNIFICANCE: The prevalence of AD was 8.3% (95%CI: 7.6%-9.1%) in children aged 3 to 6 in Shanghai. The prevalence of AD decreased from the center to the rural areas in Shanghai.
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- 2012
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44. MicroRNA-574-5p was pivotal for TLR9 signaling enhanced tumor progression via down-regulating checkpoint suppressor 1 in human lung cancer.
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Qinchuan Li, Xiaoman Li, Zhongliang Guo, Feng Xu, Jingyan Xia, Zhongmin Liu, and Tao Ren
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Medicine ,Science - Abstract
Accumulating data suggested that functional expression of Toll-like receptors (TLRs) in tumor cells was involved in tumor progression. Our previous study demonstrated that TLR9 signaling could enhance the tumor progression of human lung cancer cells in vitro and in vivo. We further showed that miR-574-5p was the mostly up-regulated miRNA in human lung cancer cells under TLR9 signaling by miRNA array analysis. Here we characterized the potential role of miRNA-574-5p in enhanced tumor progression induced by TLR9 signaling in human lung cancer. We confirmed that TLR9 signaling effectively elevated the expression of miR-574-5p in human lung cancer cells. Notably, we found that down-regulation of miRNA-574-5p using miR-574-5p inhibitor in vitro or miR-574-5p sponge in vivo significantly abrogated the enhanced tumor progression induced by TLR9 signaling. Further studies showed that miR-574-5p was an important player associated with enhanced tumor progression of human lung cancer cells. Notably, we identified checkpoint suppressor 1 (Ches1) as the dominant direct target for miRNA-574-5p to confer the TLR9 signaling enhanced tumor progression. We revealed that over-expression of Ches1 significantly inhibited the cell cycle entry of human lung cancer cells. Finally, we revealed that the expression of miR-574-5p was positively correlated with TLR9 and reversely correlated with Ches1 in lung cancer patients. Our findings not only facilitated the further understanding of the crosstalk between miRNAs and TLRs in tumor biology, but also provided novel potential candidates for treatment of cancer.
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- 2012
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45. Combined EGFR and VEGFR versus single EGFR signaling pathways inhibition therapy for NSCLC: a systematic review and meta-analysis.
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Xinji Zhang, Yesheng Li, Hui Li, Yingyi Qin, Chong Bai, Feng Xu, Tianyi Zhu, Jinfang Xu, Mengjie Wu, Chaoxiang Wang, Lixin Wei, and Jia He
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Medicine ,Science - Abstract
BACKGROUND: Lung cancer is a heterogeneous disease with multiple signaling pathways influencing tumor cell survival and proliferation, and it is likely that blocking only one of these pathways allows others to act as salvage or escape mechanisms for cancer cells. Whether combined inhibition therapy has greater anti-tumor activity than single inhibition therapy is a matter of debate. Hence, a meta-analysis comparing therapy inhibiting both VEGFR and EGFR signaling pathways with that inhibiting EGFR signaling pathway alone was performed. METHODOLOGY AND PRINCIPAL FINDINGS: We searched PubMed, EMBASE database and the proceedings of major conferences for relevant clinical trials. Outcomes analyzed were objective tumor response rate (ORR), progression-free survival (PFS), overall survival (OS) and toxicity. Besides, subgroup analyses were performed to investigate whether the combined inhibition therapy is best performed using combination of selective agents or a single agent with multiple targets. Six trials recruiting 3,302 patients were included in the analysis. Combined inhibition therapy was associated with a 3% improvement in OS as compared with single-targeted therapy, but this difference was not statistically significant (HR, 0.97; 95% CI, 0.89-1.05; P=0.472). Patients receiving combined inhibition therapy had significant longer PFS than the group with single-targeted therapy (HR, 0.80; 95% CI, 0.67-0.95; P=0.011). There was no difference in the ORR between the groups (OR, 1.44; 95% CI, 0.95-2.18; P=0.085). Subgroup analysis revealed that combined inhibition therapy using combination regimens was associated with statistically significant improvement in both ORR and PFS. Toxicity was greater in combined inhibition therapy. CONCLUSIONS: There is no evidence to support the use of combined inhibition therapy in unselected patients with advanced NSCLC. However, given the significant advantage in ORR and PFS, combined inhibition therapy using combination regimens may be considered for further evaluation in subsets of patients who may benefit from this treatment.
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- 2012
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46. Adoptive immunotherapy in postoperative hepatocellular carcinoma: a systemic review.
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Feng Xie, Xinji Zhang, Hui Li, Tao Zheng, Feng Xu, Rongxi Shen, Long Yan, Jiamei Yang, and Jia He
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Medicine ,Science - Abstract
PURPOSE: The effectiveness of immunotherapy for postoperative hepatocellular carcinoma patients is still controversial. To address this issue, we did a systemic review of the literatures and analyzed the data with emphasis on the recurrence and survival. METHODS: We searched six randomized controlled trials that included adoptive immunotherapy in the postoperative management of hepatocellular carcinoma and compared with non-immunotherapy postoperation. A meta-analysis was carried out to examine one- and 3-year recurrence and survival. RESULTS: The overall analysis revealed significantly reduced risk of 1-year recurrence in patients receiving adoptive immunotherapy (OR=0.35; 95% CI, 0.17 to 0.71; p=0.003), in that the risk of 3-year recurrence with a pooled OR estimated at 0.31 (95% CI 0.16 to 0.61; p=0.001). However, no statistically significant difference was observed for 3-year survival between groups with adoptive immunotherapy and without adjuvant treatment (OR=0.91; 95% CI, 0.45 to 1.84; P=0.792). CONCLUSIONS: Adjuvant immunotherapy with cytokine induced killer cells or lymphokine activated killer cells may reduce recurrence in postoperative hepatocellular carcinoma patients, but may not improve survival.
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- 2012
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47. Living bacterial sacrificial porogens to engineer decellularized porous scaffolds.
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Feng Xu, BanuPriya Sridharan, Naside Gozde Durmus, ShuQi Wang, Ahmet Sinan Yavuz, Umut Atakan Gurkan, and Utkan Demirci
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Medicine ,Science - Abstract
Decellularization and cellularization of organs have emerged as disruptive methods in tissue engineering and regenerative medicine. Porous hydrogel scaffolds have widespread applications in tissue engineering, regenerative medicine and drug discovery as viable tissue mimics. However, the existing hydrogel fabrication techniques suffer from limited control over pore interconnectivity, density and size, which leads to inefficient nutrient and oxygen transport to cells embedded in the scaffolds. Here, we demonstrated an innovative approach to develop a new platform for tissue engineered constructs using live bacteria as sacrificial porogens. E.coli were patterned and cultured in an interconnected three-dimensional (3D) hydrogel network. The growing bacteria created interconnected micropores and microchannels. Then, the scafold was decellularized, and bacteria were eliminated from the scaffold through lysing and washing steps. This 3D porous network method combined with bioprinting has the potential to be broadly applicable and compatible with tissue specific applications allowing seeding of stem cells and other cell types.
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- 2011
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48. Blood banking in living droplets.
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Josh Samot, Sangjun Moon, Lei Shao, Xiaohui Zhang, Feng Xu, Youngseok Song, Hasan Onur Keles, Laura Matloff, Jordan Markel, and Utkan Demirci
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Medicine ,Science - Abstract
Blood banking has a broad public health impact influencing millions of lives daily. It could potentially benefit from emerging biopreservation technologies. However, although vitrification has shown advantages over traditional cryopreservation techniques, it has not been incorporated into transfusion medicine mainly due to throughput challenges. Here, we present a scalable method that can vitrify red blood cells in microdroplets. This approach enables the vitrification of large volumes of blood in a short amount of time, and makes it a viable and scalable biotechnology tool for blood cryopreservation.
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- 2011
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49. Fluid mechanics in dentinal microtubules provides mechanistic insights into the difference between hot and cold dental pain.
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Min Lin, Zheng Yuan Luo, Bo Feng Bai, Feng Xu, and Tian Jian Lu
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Medicine ,Science - Abstract
Dental thermal pain is a significant health problem in daily life and dentistry. There is a long-standing question regarding the phenomenon that cold stimulation evokes sharper and more shooting pain sensations than hot stimulation. This phenomenon, however, outlives the well-known hydrodynamic theory used to explain dental thermal pain mechanism. Here, we present a mathematical model based on the hypothesis that hot or cold stimulation-induced different directions of dentinal fluid flow and the corresponding odontoblast movements in dentinal microtubules contribute to different dental pain responses. We coupled a computational fluid dynamics model, describing the fluid mechanics in dentinal microtubules, with a modified Hodgkin-Huxley model, describing the discharge behavior of intradental neuron. The simulated results agreed well with existing experimental measurements. We thence demonstrated theoretically that intradental mechano-sensitive nociceptors are not "equally sensitive" to inward (into the pulp) and outward (away from the pulp) fluid flows, providing mechanistic insights into the difference between hot and cold dental pain. The model developed here could enable better diagnosis in endodontics which requires an understanding of pulpal histology, neurology and physiology, as well as their dynamic response to the thermal stimulation used in dental practices.
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- 2011
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50. Correlated mutation analysis on the catalytic domains of serine/threonine protein kinases.
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Feng Xu, Pan Du, Hongbo Shen, Hairong Hu, Qi Wu, Jun Xie, and Long Yu
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Medicine ,Science - Abstract
BACKGROUND:Protein kinases (PKs) have emerged as the largest family of signaling proteins in eukaryotic cells and are involved in every aspect of cellular regulation. Great progresses have been made in understanding the mechanisms of PKs phosphorylating their substrates, but the detailed mechanisms, by which PKs ensure their substrate specificity with their structurally conserved catalytic domains, still have not been adequately understood. Correlated mutation analysis based on large sets of diverse sequence data may provide new insights into this question. METHODOLOGY/PRINCIPAL FINDINGS:Statistical coupling, residue correlation and mutual information analyses along with clustering were applied to analyze the structure-based multiple sequence alignment of the catalytic domains of the Ser/Thr PK family. Two clusters of highly coupled sites were identified. Mapping these positions onto the 3D structure of PK catalytic domain showed that these two groups of positions form two physically close networks. We named these two networks as theta-shaped and gamma-shaped networks, respectively. CONCLUSIONS/SIGNIFICANCE:The theta-shaped network links the active site cleft and the substrate binding regions, and might participate in PKs recognizing and interacting with their substrates. The gamma-shaped network is mainly situated in one side of substrate binding regions, linking the activation loop and the substrate binding regions. It might play a role in supporting the activation loop and substrate binding regions before catalysis, and participate in product releasing after phosphoryl transfer. Our results exhibit significant correlations with experimental observations, and can be used as a guide to further experimental and theoretical studies on the mechanisms of PKs interacting with their substrates.
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- 2009
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