oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 197 )

2018 ( 1796 )

2017 ( 1680 )

2016 ( 1684 )

Custom range...

Search Results: 1 - 10 of 121403 matches for " CHEN Xiao-qing "
All listed articles are free for downloading (OA Articles)
Page 1 /121403
Display every page Item
RP-HPLC-DAD detrmination of flavonoids: separation of quercetin, luteolin and apigenin in Marchantia Convoluta
Xiao-qing Chen,Jian-bo Xiao
Iranian Journal of Pharmaceutical Research , 2005,
Abstract: High performance liquid chromatography coupled with photodiode array detector (HPLCDAD)has been reported to quantify isolated flavonoids or these compounds in complex biological matrices, such as Chinese herbal drugs and products from factories. This work was designed, therefore, to develop an HPLC-DAD system to separate quercetin, luteolin and apigenin and to quantify them in extractive solutions from Marchantia convoluta. Flavonoids were analyzed on a Kromasil RP-C18 column; using a mobile phase, consisted of methanolacetonitrile-acetic acid-phosphoric acid-H2O (200:100:10:10:200, V/V); under the following conditions: detecting wavelength, 352 nm; flow rate, 0.60 ml/min; the sensitivity, 0.05 AUFS and the volume of injecting sample, 6.0 μl. The HPLC system was operated at ambient temperature (28±1°C). The method showed linearity for quercetin, luteolin and apigenin in the range 2.0-20.8, 2.2-24.0 and 1.6-20.0 μg/ml respectively, and the R.S.D. of the slope of the three lines was, respectively, 0.33%, 1.21% and 2.49% for quercetin, luteolin and apigenin.The aqueous and ethanol 80% extractive solutions showed linear response 1.5-15 μl/ml and ethanol 50% extractive solution in range 1.0-10 μl/ml. Precision and accuracy were determined for ethanol 80% extractive solution, in concentration of 10 μl/ml. The recoveries were 95.92-98.10%, 92.18-95.13% and 98.72-103.19% for quercetin, luteolin and apigenin respectively.RSD of results was 2.83-3.62%. The HPLC method showed an excellent performance in separating the flavonoids quercetin, luteolin and apigenin in Marchantia convoluta extracts, since the presence of interference has been previously evaluated and the mobile phase waschose carefully.
Effect of erythropoietin on dynamic changes of TLR4,NF-κB,and IL-6 in rat model with necrotizing enterocolitis
Xiao-qing CHEN,Hua XU,Xiao-ping LUO
Medical Journal of Chinese People's Liberation Army , 2011,
Abstract: Objective To explore the protective effect and the mechanism of erythropoietin(EPO) on dynamic expressions of TLR-4,NF-κB,and IL-6 in the intestinal tissue of neonatal rat model with necrotizing enterocolitis(NEC).Methods A total of 90 SD rats(3 days old) were divided randomly into 3 groups(30 each) as follows: normal control group,NEC group,and EPO group.The NEC rat model was established by feeding the subjects with rat-milk substitutes after separation from the mother rats.The subjects were then exposed to hypoxia and cold stress.The EPO-treated rats were fed with the substitute of rat-milk containing EPO(0.1U/ml),and were exposed to hypoxia and cold stress as well.The rats in the control group were raised by their mothers and received no intervention.Ten rats from each group were sacrificed at 24,48,and 72h,respectively.The last 3cm of the terminal ileum was excised and the histological changes of the intestinal tissues were scored after H-E staining.Scores ≥2 were considered NEC.Fluorescence quantitative PCR was used to evaluate the dynamic levels of TLR4 mRNA and NF-κB mRNA.ELISA was used to determine the expression of IL-6.Results The TLR4 mRNA expression in the NEC group increased at 24h,peaked at 48h,and slightly decreased at 72h.The expressions in all time points increased significantly compared with those in the control group(P < 0.01).The rats in the EPO group expressed high levels of TLR4 mRNA at 24h.However,the expression rapidly declined later,and was significantly lower at 48 and 72h compared with those in the NEC group(P < 0.01).The expressions of NF-κB mRNA and IL-6 were significantly higher in the NEC group than in the control group at 48 and 72 h(P < 0.01).The expressions considerably increased in the EPO group at 48h,then declined at 72h,and were significantly lower than those in the NEC group(P < 0.01).No apparent pathological change was found in all groups at the time points of 24 and 48h.However,tissue lesion was observed in the NEC and EPO groups at 72 h,and the histological score was significantly higher in the NEC group(2.83±0.56) than in the EPO group(1.53±0.35,P < 0.01).Conclusions In the intestinal tract of the neonatal rat with NEC,innate immune response initiates earlier than the acquired immune response.Inflammatory response appears ahead of the tissue lesion,implying that the inflammatory response induces lesion.The enteral administration of human milk with a physiologic concentration of EPO may downregulate the TLR4 mRNA expression and inhibit the release of inflammatory mediators,thereby reducing intestinal tissue inju
Effect of erythropoietin on intestinal injury and bacterial translocation in neonatal rat model of necrotizing enterocolitis
Xiao-qing CHEN,Xiao-ping LUO
Medical Journal of Chinese People's Liberation Army , 2012,
Abstract: Objective  To observe the influence of erythropoietin (EPO) on intestinal histopathological changes and bacterial translocation (BT) in neonatal rat model of necrotizing enterocolitis (NEC), and explore the protective effect of EPO against NEC. Methods  Seventy-five three-day-old SD rat pups were randomly divided into three groups (25 in each group): normal control group, NEC model group and EPO intervention group. The rat pups in normal control group were placed together with their mothers and breast fed, receiving no other intervention. NEC model group rats were separated from their mothers, housed in an incubator, and gavaged with rat-milk substitute, then experienced hypoxia (breathing 100% nitrogen gas for 90s) and cold stress (4℃ for 10min) three times daily for 3 days. EPO intervention group rats were fed with the substitute of rat-milk supplemented with 0.1U/ml of EPO, and they were also given hypoxia and cold stress similar to that of the NEC model group. Blood samples were obtained via cardiac puncture, and 2-cm-length of terminal ileum proximal to the ileocecal valve were obtained from the animals on the 4th day. The histopathological changes in terminal ileum were scored after hematoxylin-eosin (HE) staining, and the scores ≥2 were defined as NEC. To determine the incidence of bacterial translocation, 16S rRNA real-time fluorescence quantitative PCR was used to detect the bacterial DNA in blood samples. Results  Compared with the NEC model group, the mean rank-sum rate of the intestinal histopathological score (39.4583 vs 53.8696), NEC incidence [25%(6/24) vs 57%(13/23)] and bacterial translocation rate [17% (4/24) vs 65%(15/23)] in EPO intervention group were significantly lowered (P < 0.05, P < 0.01). Conclusion  Enteral EPO administration is not only effective for reduction of the severity and incidence of NEC, but also for decrease of the bacterial translocation rate in neonatal rat models.
(3S,NR)-3-Hydroxymethyl-2-methyl-2-(3-methylbut-2-en-1-yl)-1,2,3,4-tetrahydroisoquinolinium bromide–1,1′-bi-2-naphthol (1/1)
Xiao-Qing Wu,Qing-Chun Huang,Xiao-Zhen Chen,Guo-You Li
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810007944
Abstract: In the title compound, C16H24NO+·Br ·C20H14O2, the N-heterocyclic six-membered ring assumes a half-chair conformation. The two naphthalene ring systems are nearly perpendicular to one another, making a dihedral angle of 89.5 (2)°. Intermolecular O—H...Br hydrogen bonding helps to stabilize the crystal structure.
Predictive value of neutrophil infiltration as a marker of Helicobacter pylori infection
Xiao-Qing Xu,Zhen-Hua Wang,Jing-Xian Liao,Xiao-Yu Chen
World Journal of Gastroenterology , 2012, DOI: 10.3748/wjg.v18.i36.5101
Abstract: AIM: To evaluate the predictive value of neutrophil infiltration as a marker of Helicobacter pylori (H. pylori) infection. METHODS: A total of 315 patients with dyspepsia symptoms who underwent upper gastrointestinal endoscopy were enrolled in this study. Biopsies were evaluated using the updated Sydney system. The medication history of all patients in the preceding 4 wk was recorded. The diagnosis of H. pylori infection was based on 13C-urea breath test at least 4 wk after withdrawal of antisecretory drugs, antibiotics and related drugs. For the patients with subtotal gastrectomy, the diagnosis of H. pylori infection was based on anti-H. pylori immunoglobulin G (IgG) antibody. Serum anti-H. pylori IgG antibody was measured by enzyme-linked immunosorbent assays (Biohit, Finland). RESULTS: The sensitivity, specificity, positive predictive value and negative predictive value of neutrophil infiltration in the diagnosis of H. pylori infection were 92.3%, 83.5%, 77.4% and 94.7%, respectively. Neutrophil infiltration of gastric mucosa in the histological analysis was strongly associated with H. pylori infection (77.4% vs 5.3% in the neutrophil infiltration negative group, P = 0.000). Moderate neutrophil infiltration was more frequent in H. pylori infection when compared to mild infiltration (81.8% and 75%, respectively), but did not reach statistical significance. For those patients with negative rapid urease test, H. pylori was detected in 73.2% of patients with positive neutrophil infiltration on histology. In patients with subtotal gastrectomy, the diagnostic accuracy of neutrophil infiltration in H. pylori infection was 50%. CONCLUSION: Neutrophil infiltration is closely associated with H. pylori and may be recognized as a sign of this infection.
A Robust and Efficient Facial Feature Tracking Algorithm
一种鲁棒高效的人脸特征点跟踪方法

HUANG Chen,DING Xiao-Qing,FANG Chi,
黄琛
,丁晓青,方驰

自动化学报 , 2012,
Abstract: Facial feature tracking obtains precise information of facial components in addition to the coarse face position and moving track, and is important to computer vision. The active appearance model (AAM) is an efficient method to describe the facial features. However, it suffers from the sensitivity to initial parameters and may easily be stuck in local minima due to the gradient-descent optimization, which makes the AAM based tracker unstable in the presence of large pose, illumination and expression changes. In the framework of multi-view AAM, a real time pose estimation algorithm is proposed by combining random forest and linear discriminate analysis (LDA) to estimate and update the head pose during tracking. To improve the robustness to variations in illumination and expression, a modified online appearance model (OAM) is proposed to evaluate the goodness of AAM fitting, then the appearance model of AAM is updated adaptively using the incremental principle component analysis (PCA). The experimental results show that the proposed algorithm has both efficiency and robustness.
Cluster consensus of second-order multi-agent systems via pinning control

Lu Xiao-Qing,Francis Austin,Chen Shi-Hua,

中国物理 B , 2010,
Abstract: This paper investigates the cluster consensus problem for second-order multi-agent systems by applying the pinning control method to a small collection of the agents. Consensus is attained independently for different agent clusters according to the community structure generated by the group partition of the underlying graph and sufficient conditions for both cluster and general consensus are obtained by using results from algebraic graph theory and the LaSalle Invariance Principle. Finally, some simple simulations are presented to illustrate the technique.
Angiotensin II and Angiotensin-(1-7) in Paraventricular Nucleus Modulate Cardiac Sympathetic Afferent Reflex in Renovascular Hypertensive Rats
Hai-Jian Sun, Peng Li, Wei-Wei Chen, Xiao-Qing Xiong, Ying Han
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0052557
Abstract: Background The enhanced cardiac sympathetic afferent reflex (CSAR) is involved in the sympathetic activation that contributes to the pathogenesis and progression of hypertension. Activation of AT1 receptors by angiotension (Ang) II in the paraventricular nucleus (PVN) augments the enhanced CSAR and sympathetic outflow in hypertension. The present study is designed to determine whether Ang-(1-7) in PVN plays the similar roles as Ang II and the interaction between Ang-(1-7) and Ang II on CSAR in renovascular hypertension. Methodology/Principal Findings The two-kidney, one-clip (2K1C) method was used to induce renovascular hypertension. The CSAR was evaluated by the renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) responses to epicardial application of capsaicin in sinoaortic-denervated and cervical-vagotomized rats with urethane and α-chloralose anesthesia. Either Ang II or Ang-(1-7) in PVN caused greater increases in RSNA and MAP, and enhancement in CSAR in 2K1C rats than in sham-operated (Sham) rats. Mas receptor antagonist A-779 and AT1 receptor antagonist losartan induced opposite effects to Ang-(1-7) or Ang II respectively in 2K1C rats, but losartan had no effects in Sham rats. Losartan but not the A-779 abolished the effects of Ang II, while A-779 but not the losartan blocked the effects of Ang-(1-7). PVN pretreatment with Ang-(1-7) dose-dependently augmented the RSNA, MAP, and CSAR responses to the Ang II in 2K1C rats. Ang II level, AT1 receptor and Mas receptor protein expression in PVN increased in 2K1C rats compared with Sham rats but Ang-(1-7) level did not. Conclusions Ang-(1-7) in PVN is as effective as Ang II in enhancing the CSAR and increasing sympathetic outflow and both endogenous Ang-(1-7) and Ang II in PVN contribute to the enhanced CSAR and sympathetic outflow in renovascular hypertension. Ang-(1-7) in PVN potentiates the effects of Ang II in renovascular hypertension.
Lipoxin A4-Induced Heme Oxygenase-1 Protects Cardiomyocytes against Hypoxia/Reoxygenation Injury via p38 MAPK Activation and Nrf2/ARE Complex
Xiao-Qing Chen, Sheng-Hua Wu, Yu Zhou, Yan-Rong Tang
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0067120
Abstract: Objective To investigate whether lipoxin A4 (LXA4) increases expression of heme oxygenase-1(HO-1) in cardiomyocytes, whether LXA4-induced HO-1 protects cardiomyocytes against hypoxia/reoxygenation (H/R) injury, and what are the mechanisms involved in the LXA4-induced HO-1 induction. Methods Rat cardiomyocytes were exposed to H/R injury with or without preincubation with LXA4 or HO-1 inhibitor ZnPP-IX or various signal molecule inhibitors. Expressions of HO-1 protein and mRNA were analyzed by using Western blot and RT-PCR respectively. Activity of nuclear factor E2-related factor 2 (Nrf2) binding to the HO-1 E1 enhancer was assessed by chromatin immunoprecipitation. Nrf2 binding to the HO-1 antioxidant responsive element (ARE) were measured by using electrophoretic mobility shift assay. Results Pretreatment of the cells undergoing H/R lesion with LXA4 significantly reduced the lactate dehydrogenase and creatine kinase productions, increased the cell viability, and increased the expressions of HO-1 protein and mRNA and HO-1 promoter activity. HO-1 inhibition abolished the protective role of LXA4 on the cells undergoing H/R lesion. LXA4 increased p38 mitogen-activated protein kinase (p38 MAPK) activation, nuclear translocation of Nrf2, Nrf2 binding to the HO-1 ARE and E1 enhancer in cardiomyocytes with or without H/R exposure. Conclusion The protection role of LXA4 against H/R injury of cardiomyocytes is related to upregulation of HO-1, via activation of p38 MAPK pathway and nuclear translocation of Nrf2 and Nrf2 binding to the HO-1 ARE and E1 enhancer, but not via activation of phosphatidyinositol-3-kinase or extracellular signal-regulated kinase pathway.
1-(3,4-Dihydroxyphenyl)-2-(4-fluorophenyl)ethanone
Xiao-Qing Song
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808035733
Abstract: In the title compound, C14H11FO3, the dihedral angle between the aromatic rings is 69.11 (8)°. An intramolecular O—H...O hydrogen bond is present. Intermolecular O—H...O interactions help to establish the packing.
Page 1 /121403
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.