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Biomedical subjects

Wei Liu

Publications and source records attributed to Wei Liu.

At least 397 records · Page 22Linked to original sources
PubMed2003

Construction and characterization of a novel 13.34-fold chicken bacterial artificial chromosome library.

A chicken bacterial artificial chromosome (BAC) library consisting of 138,240 clones was constructed in vector pBeloBAC11 with genomic DNA isolated from female white-silk chicken. An average insert size of 118 kb was estimated from 452 randomly isolated clones, which indicate the library to be approximate 13.34-fold genome coverage. For the demonstration of the probability to pick out any unique genes or DNA markers from the library, 8 single-copy genes were screened out and the positive clones were yielded between 2 and 15 with an average of 11.125, in agreement with the estimated high genomic coverage of this library. Positive superpools were obtained for 40 microsatellite markers selected from different regions of chicken genome. The number of positive superpools for each marker varies from 1 to 15 with an average of 9.475.

Animals↗
PubMed2003

Human immunodeficiency virus knowledge and attitudes among hospital-based healthcare professionals in Guangxi Zhuang Autonomous Region, People's Republic of China.

BACKGROUND AND OBJECTIVE: Since the discovery of human immunodeficiency virus (HIV) on the Chinese mainland in 1985, the virus has spread to all provinces and autonomous regions. Although much research emphasis has been placed on studying behaviors and transmission knowledge among high-risk populations, especially drug abusers and commercial sex workers, little has been done to measure understanding within other risk groups. The objective of this study was to investigate HIV/acquired immunodeficiency syndrome (AIDS) knowledge and attitudes among hospital-based healthcare professionals in Guangxi Zhuang Autonomous Region in southern China. METHODS: Data were gathered through a questionnaire completed by a convenience sample of individuals from three diverse hospitals. RESULTS: Insufficient knowledge of the disease and its transmission resulted in more than 90% of the respondents expressing apprehension about contracting the virus and nearly 24% expressing reservations about caring for infected patients. CONCLUSION: Uncorrected, such attitudes and knowledge deficiencies have the potential to impact negatively on the quality of care, patient-practitioner safety, and proper postexposure prophylaxis.

Attitude of Health Personnel↗
PubMed2003

A closer view of tissue engineering in China: the experience of tissue construction in immunocompetent animals.

Tissue engineering started in late 1980s and is now well established and progressing rapidly in Western developed countries. However, the development of tissue-engineering research in China remains relatively unknown to the international society of tissue engineering. Although involved in all areas of tissue-engineering research, including the creation of new scaffold materials, in vitro studies of seed cells, application of growth factors, and modification of seed cells and scaffold materials, China has put special emphasis on tissue construction in large mammalian animals in order to establish a solid scientific basis for clinical application of engineered tissues. To provide a closer view of tissue-engineering research in China, this article reviews our experience in tissue construction and tissue repair using immunocompetent animals such as sheep, pig, and dog as well as hen and rabbit. The engineered tissues include bone, cartilage, tendon, skin, blood vessels, cornea, and peripheral nerves.

Animals↗
PubMed2003

Study on the determination of polyphenols in tobacco by HPLC coupled with ESI-MS after solid-phase extraction.

A high-performance liquid chromatography method coupled with electrospray ionization-mass spectrometry for the determination of polyphenols in tobacco is studied. The polyphenols are extracted from a tobacco sample by being refluxed in a boiling water bath with 80% methanol and purified by solid-phase extraction with a C18 cartridge. The chlorogenic acid, rutin, scopoletin, caffeic acid, scopolin, and other polyphenols are satisfactorily separated on a Nova-Pak C18 chromatographic column (3.9 x 150 mm) with methanol and 0.05 mol/L potassium dihydrogen phosphate buffer solution gradient elution as mobile phase at a flow rate of 0.5 mL/min. Each of the polyphenols is monitored by photodiode array detector at its maximum wavelength: chlorogenic acid, 326.1 nm; rutin, 354.8 nm; scopoletin, 344.0 nm; caffeic acid, 323.7 nm; and scopolin, 365.2 nm. The limits of detection are: 100 ng/mL for chlorogenic acid, 125 ng/mL for rutin, 60 ng/mL for scopoletin, 50 ng/mL for caffeic acid, and 100 ng/mL for scopolin. The key polyphenols in tobacco are identified by comparing the retention time, the UV-spectrum, and the mass spectra with those of the standards. The recovery of tobacco polyphenols is 94-105%, and the relative standard deviations are 1.28-1.49%. This method is successfully applied to qualitatively and quantitatively analyze the polyphenols in tobacco with good results.

Chromatography, High Pressure Liquid↗
PubMed2003

The calcimimetic AMG 073 as a potential treatment for secondary hyperparathyroidism of end-stage renal disease.

Current treatment of secondary hyperparathyroidism in chronic kidney failure with calcium and active vitamin D is potentially limited by hypercalcemia and hyperphosphatemia. AMG 073 represents a new class of compounds for the treatment of hyperparathyroidism known as calcimimetics, which reduce parathyroid hormone (PTH) synthesis and secretion by increasing the sensitivity of the parathyroid calcium-sensing receptor (CaR) to extracellular calcium. The current study evaluates the efficacy and safety of AMG 073 when added to conventional treatment of secondary hyperparathyroidism in end-stage renal disease (ESRD). Seventy-one hemodialysis patients with uncontrolled secondary hyperparathyroidism, despite standard therapy with calcium, phosphate binders, and active vitamin D sterols, were treated in this 18-wk, dose-titration study with single daily oral doses of AMG 073/placebo up to 100 mg. Changes in plasma PTH, serum calcium, serum phosphorus, and calcium x phosphorus levels were compared between AMG 073 and placebo groups. Mean PTH decreased by 33% in the AMG 073 patients compared with an increase of 3% in placebo patients (P = 0.001). A significantly greater proportion of AMG 073 patients (44%) had a mean PTH < or = 250 pg/ml compared with placebo patients (20%; P = 0.029). Also, a significantly greater proportion of AMG 073 patients (53%) had a decrease in PTH > or =30% compared with placebo patients (23%; P = 0.009). Calcium x phosphorus levels decreased by 7.9% in AMG 073 patients compared with an increase of 11.3% in placebo patients (P = 0.013). Adverse event rates were low and mostly mild to moderate in severity; however, the incidence of vomiting was higher in AMG 073 patients. In this study, the calcimimetic AMG 073 at doses up to 100 mg for 18 wk provided a safe and effective means to attain significant reductions in PTH and calcium x phosphorus levels in ESRD patients. AMG 073 represents a novel and promising therapy to improve the management of secondary hyperparathyroidism.

Adult↗
PubMed2003

Attenuation of itraconazole fungicidal activity following preexposure of Aspergillus fumigatus to fluconazole.

Fluconazole (FLC), a triazole with limited activity against Aspergillus species, is frequently used as prophylaxis in leukemia patients and bone marrow transplant recipients. Prior FLC use has been associated with an increasing incidence of invasive aspergillosis in these patients. We hypothesized that prior exposure of Aspergillus fumigatus to FLC could result in altered in vitro susceptibility of this fungus to other, more active triazoles. Thus, we performed serial passages of conidia of 10 clinical isolates of A. fumigatus (all itraconazole [ITC] susceptible) on FLC-containing yeast agar glucose plates. The MICs and minimal fungicidal concentrations (MFCs) of amphotericin B, FLC, ITC, and voriconazole (VRC) for A. fumigatus conidia were measured following four passages on FLC-containing medium according to the National Committee for Clinical Laboratory Standards microdilution method. Serial passages on FLC-containing plates resulted in a fourfold increase in the MFCs (but not the MICs) of ITC for nine isolates. The attenuated ITC fungicidal activity against A. fumigatus following FLC preexposure was medium independent and was also observed against FLC-preexposed A. fumigatus hyphae with the viability staining FUN-1 dye. Moreover, FLC preexposure of A. fumigatus conidia resulted in an analogous increase in the MFCs (but not the MICs) of VRC. Our findings suggest that preexposure of A. fumigatus to FLC attenuates the in vitro fungicidal activity of subsequent ITC use against it. This phenotypic adaptation is not captured by a routine MIC determination but requires MFC measurement. The in vivo significance of this in vitro phenomenon requires further investigation.

Antifungal Agents↗
PubMed2003

A generic high-throughput screening assay for kinases: protein kinase a as an example.

A generic high-throughput screening assay based on the scintillation proximity assay technology has been developed for protein kinases. In this assay, the biotinylated (33)P-peptide product is captured onto polylysine Ysi bead via avidin. The scintillation signal measuring the product formation increases linearly with avidin concentration due to effective capture of the product on the bead surface via strong coulombic interactions. This novel assay has been optimized and validated in 384-well microplates. In a pilot screen, a signal-to-noise ratio of 5- to 9-fold and a Z' factor ranging from 0.6 to 0.8 were observed, demonstrating the suitability of this assay for high-throughput screening of random chemical libraries for kinase inhibitors.

Adenosine Triphosphate↗
PubMed2003

Myostatin is a skeletal muscle target of growth hormone anabolic action.

Myostatin is a cytokine that has recently been shown to selectively and potently inhibit myogenesis. To investigate the mechanisms of anabolic actions of GH on skeletal muscle growth, we examined the in vitro and in vivo effects of GH on myostatin regulation. Twelve GH-deficient hypopituitary adult subjects were treated with recombinant GH (5 micro g/kg.d) in a double-blind, placebo-controlled fashion. Body composition and physical function were assessed and skeletal muscle biopsies from the vastus lateralis performed at 6-monthly intervals during 18 months of treatment. Myostatin mRNA expression was significantly inhibited to 31 +/- 9% (P < 0.001) of control by GH but not by placebo administration (79 +/- 11%) as determined by quantitative real-time PCR normalized for the housekeeping glyceraldehyde-3-phosphate dehydrogenase gene. The inhibitory effect of GH on myostatin was sustained after 12 and 18 months of GH treatment. These effects were associated with increases in lean body mass and translated into enhanced aerobic performance as determined by maximal oxygen uptake and ventilation threshold. Parallel in vitro studies of skeletal muscle cells demonstrated significant reduction of myostatin expression by myotubes in response to GH, compared with vehicle treatment. Conversely, GH receptor antagonism resulted in up-regulation of myostatin in myoblasts. Given the potent catabolic actions of myostatin, our data suggest that myostatin represents a potential key target for GH-induced anabolism.

Adult↗
PubMed2003

Genetic dissection of Pitx2 in craniofacial development uncovers new functions in branchial arch morphogenesis, late aspects of tooth morphogenesis and cell migration.

Pitx2, a paired-related homeobox gene that encodes multiple isoforms, is the gene mutated in the haploinsufficient Rieger Syndrome type 1 that includes dental, ocular and abdominal wall anomalies as cardinal features. Previous analysis of the craniofacial phenotype of Pitx2-null mice revealed that Pitx2 was both a positive regulator of Fgf8 and a repressor of Bmp4-signaling, suggesting that Pitx2 may function as a coordinator of craniofacial signaling pathways. We show that Pitx2 isoforms have interchangeable functions in branchial arches and that Pitx2 target pathways respond to small changes in total Pitx2 dose. Analysis of Pitx2 allelic combinations that encode varying levels of Pitx2 showed that repression of Bmp signaling requires high Pitx2 while maintenance of Fgf8 signaling requires only low Pitx2. Fate-mapping studies with a Pitx2 cre recombinase knock in allele revealed that Pitx2 daughter cells are migratory and move aberrantly in the craniofacial region of Pitx2 mutant embryos. Our data reveal that Pitx2 function depends on total Pitx2 dose and rule out the possibility that the differential sensitivity of target pathways was a consequence of isoform target specificity. Moreover, our results uncover a new function of Pitx2 in regulation of cell motility in craniofacial development.

Abnormalities, Multiple↗
PubMed2003

Expression of recombinant XVAX2 peptide-104 of Xenopus laevis and preparation of the antibody.

An N-terminal polypeptide (XVAX2-P104) of the XVAX2 protein, which is involved in controlling the dorsoventral patterning of the retina in Xenopus laevis, was expressed and purified as a Histagged fusion protein (pHis-XVAX2-P104), and it was employed to generate an anti-XVAX2 antibody in New Zealand white rabbits. ELISA analysis shows that the titer of the antibody is as high as approximately 1:100,000. The antibody could specifically recognize the full-length XVAX2 protein in extracts of Xenopus embryos, as determined by Western Blotting.

Animals↗
PubMed2003

[Prognostic analysis of advanced non small cell lung cancer treated by sequential chemo-radiation therapy combined with traditional Chinese medicine: a report of 54 cases].

OBJECTIVE: To evaluate the influence of fewer courses and prolonged intervals of chemotherapy on survival rate of advanced non small cell lung cancer (NSCLC) patients treated by sequential chemo-radiation therapy combined with traditional Chinese medicine (TCM). METHODS: From Jan. 2000 to Dec. 2001, 54 untreated advanced NSCLC patients (2 stage IIIa, 18 stage IIIb, 34 stage IV) were treated by sequential chemo-radiation therapy combined with TCM. The courses of chemotherapy were reduced and the intervals of chemotherapy were longer than that of the standard regimen. The efficacy and survival rate were documented and the prognostic factors were analyzed. RESULTS: Complete remission (CR) was observed in 1 case and partial remission (PR) in 20 cases. The overall objective response rate was 40.4%. Median survival was 15.3 months, 1-, 2- and 3-year survival rate were 53.7%, 28.9% and 9.6% respectively. The median survival of stage III and IV were 21.8 months and 12.5 months respectively. The 1-, 2-, and 3-year survival rates of stage III were 65.0%, 49.5%, 24.7% and that of stage IV were 47.0%, 23.3%, 0%, respectively. The quality of life was improved in most of the patients. Cox's proportional hazards regression showed that improved quality of life and treatment of TCM were the significant prognostic factors of overall survival. CONCLUSION: Chemotherapy and radiotherapy combined with TCM is beneficial to extending the interval of chemotherapy, improving the quality of life, and increasing the survival rate of advanced NSCLC patients.

Adult↗
PubMed2003

[Mapping studies of type 2 diabetes mellitus gene in one family].

OBJECTIVE: To disclose the molecular genetic mechanism of type 2 diabetes mellitus and to determine chromosomal location of type 2 diabetes mellitus gene. METHODS: Genome-wide screening and genotyping were conducted in a family of type 2 diabetes mellitus, and linkage analysis by LINKAGE and GENEHUNTER package was used to determine the potential chromosomal location of the family of type 2 diabetes mellitus gene. RESULTS: Evidence of linkage was found at the long arm of chromosome 2. The maximum Lod score is 1.80 and non-parameter Lod score is 5.06. CONCLUSION: The type 2 diabetes mellitus gene of the family is located at 2q.

Adult↗
PubMed2003

[A new chromone glycoside from Cassia siamea lam].

AIM: To study the chemical constituents of the stem of Cassia siamea. METHODS: The compounds were isolated by chromatography on silica gel, and identified on the basis of spectral analysis. RESULTS: Five compounds were isolated and identified as: beta-sitosterol (I), sucrose (II), n-octacosanol (III), 2-methyl-5-(2'-hydroxypropyl)-7-hydroxy-chromone-2'-O-beta-D-glucopyranoside (IV) and piceatannol (V). CONCLUSION: Compound IV is a new compound. Compounds II, III and V were obtained from this plant for the first time.

Cassia↗
PubMed2003

[A case-control study on the vitamin D receptor gene polymorphisms and susceptibility to pulmonary tuberculosis].

OBJECTIVE: To investigate the association between the genetic polymorphisms of VDR gene and susceptibility to pulmonary tuberculosis. METHODS: Case-control study was conducted. PCR-RFLP technique was used to detect the C/T polymorphism in VDR gene. Information on related factors of tuberculosis was collected using a pre-tested questionnaire. Univariate and multivariate logistic analyses were conducted with SPSS software package. RESULTS: A sample of 76 cases and 171 controls was studied. The genotype frequencies of VDR-FF, VDR-Ff and VDR-ff were 38.2%, 44.7%, 17.1% and 52.6%, 40.9%, 6.4% respectively. VDR-ff was significantly overrepresented in case group, the OR (95% CI) was 3.668 (1.483 - 9.071) when comparing with FF genotype. The significant association remained after adjusting BCG immunization and smoking, the OR (95% CI) was 3.036 (1.117 - 8.253). CONCLUSION: The VDR-ff genotype might be associated with the susceptibility to pulmonary tuberculosis in Chinese Han population.

Adolescent↗
PubMed2003

[Construction of recombinant pEGFP/hTRT plasmid].

OBJECTIVE: To construct a plasmid which has a reporter gene for exploring the role of human telomerase reverse transcriptase(hTRT) in in-vitro cell cultivation. METHODS: hTRT was cut by restricted enzyme from plasmid pGRN145 and inserted to plasmid pEGFP-C1 (enhanced green fluorescent protein). RESULTS: Restricted enzyme analysis and DNA sequencing showed that the sequence of the pEGFP -hTRT transgenic plasmid was correct. CONCLUSION: The recombinant vector pEGFP-hTRT has been successfully constructed, and it can be used as a transgenic plasmid in generating immortalized cell lines.

DNA-Binding Proteins↗