Biomedical subjects

W Chen

Publications and source records attributed to W Chen.

At least 217 records · Page 12Linked to original sources

PubMed2001

[Changes of lipid peroxidation in liver fibrogenesis induced by dimethylnitrosamine and drugs' intervention].

OBJECTIVE: To investigate the pathological actions of lipid peroxidation implicated in liver fibrogenesis induced by dimethylnitrosamine (DMN), and the mechanism of Fuzheng Huayu 319 decoction (319 decoction) and interferon-gamma (IFN-gamma) actions against liver fibrosis. METHODS: A liver fibrotic model was induced by intraperitoneal injection of DMN in rats, and treated with 319 decoction and IFN-gamma, respectively. The liver sections were stained with HE and ponceau for collagens, and the liver functions were assayed. The contents of hepatic hydroxyproline (Hyp) and malondialdehyde (MDA) and the activities of superoxide dismutase (SOD) were measured. The correlation among SOD, MDA and Hyp was analyzed. RESULTS: In the models, hepatic collagens proliferated remarkably and fibrous septa were formed. Serum ALT activities increased. Both Hyp and MDA enhanced obviously, but SOD decreased markedly. SOD was significantly negatively correlated with MDA and Hyp, respectively (r=-0.70, -0.73, P<0.01), and MDA was significantly positively correlated with Hyp (r=0.88, P<0.01). While both 319 decoction and IFN-gamma attenuated collagen proliferation and deposition, decreased ALT level, increased SOD activity, but decreased MDA and Hyp contents. CONCLUSIONS: DMN can cause hepatic lipid peroxidation, which is closely involved in liver fibrogenesis induced by DMN. The effect against hepatic lipid peroxidation is one of the important mechanisms of 319 decoction and IFN-gamma actions against liver fibrosis.

Animals↗

PubMed2001

[Construction and expression in eukaryotic cells of HBsAg and B].

OBJECTIVE: To investigate the enhanced role of B(7-1) in gene immunization of eukaryotic vector expressing HBsAg, and further to eliminate the immunotolerance to hepatitis B virus. METHODS: B(7-1) and IRES-HBs with linker and promoter sequence prior to HBs gene were amplified with high fidelity PCR, then subcloned into plasmid pBluescriptks+, which was used to sequence. The eukaryotic expressing vector was constructed by inserting B(7-1) and IRES-HBs into plxsn. Recombinant vector was transfected into PA317 by means of lipid mixtures. Titre of pseudovirus packaged in PA317 cells was detected by infecting NIH3T3 cells. B(7-1) and HBsAg expression in PA317, NIH3T3, HepG(2), 293, EL4 cell lines was detected by RT-PCR, immunohistochemistry and ELISA, respectively. RESULTS: No change was found in the sequences of target genes amplified by high fidelity PCR compared with the known sequences. Plxsn-B(7-1)-HBs was constructed by first inserting B(7-1) into plxsn with enzyme EcoRI/XhoI, then IRES-HBs was inserted in the same way with enzyme XhoI/BamHI. 43 and 90 G418-resistant clones were obtained two weeks later after 1:10 and 1:5 passages at 24 hours after transfection. Titre of the peudovirus was 5.4x10(5) CFU/ml. B(7-1) was expressed in all the cell lines above by RT-PCR test. The contents of HBsAg in the supernatant of the PA317, NIH3T3, HepG(2), and 293 cells at 24, 48, 72 hours intervals were 0.15, 0.11, 0.20, 0.13; 0.63, 0.47, 0.76, 0.58; 0.77, 0.61, 0.89, 0.69, respectively. CONCLUSIONS: The retroviral vector expressing B(7-1) and HBsAg simultaneously is constructed successfully. The target antigens are expressed in above cell lines in vitro after transfection with lipids mixtures. It may be used to conduct gene immunization and to investigate the role of B(7-1) on HBsAg immune response, which may be further used to the prevention and therapy of hepatitis B.

Animals↗

PubMed2001

[Cloning and expression of maltooligosyltrehalose synthase from Sulfolobus acidocaldarius in Escherichia coli].

The gene of MTSase (maltooligosyltrehalose synthase) from Sulfolobus acidocaldarius ATCC49426 was amplified by PCR. The primers were designed according to the published sequence of homologous gene from Sulfolobus acidocaldarius ATCC33909. This gene was inserted into the plasmid pBV220 and the resultant recombinant plasmid pBV220-GT was transformed to E. coli DH5 alpha. The activity of recombinant enzyme was about 10 u/g(wet cell). In order to improve the expression level of target protein, some nucleotides in the 3' and 5' of the gene were modified to optimize the second structure of mRNA by PCR amplification using the new primers devised according to the biosoftware GOLDKEY2.0. As a result, the activity of recombinant enzyme increase to 19.8 u/g(wet cell). Then, the helping plasmid pUBS520 which carried the gene encoding the tRNA of rare codons AGG and AGA was transformed to the recombinant strain. But it took little effect.

Cloning, Molecular↗

PubMed2001

Nuclear receptor-mediated repression of human cholesterol 7alpha-hydroxylase gene transcription by bile acids.

Hydrophobic bile acids strongly repressed transcription of the human cholesterol 7alpha-hydroxylase gene (CYP7A1) in the bile acid biosynthetic pathway in the liver. Farnesoid X receptor (FXR) repressed CYP7A1/Luc reporter activity in a transfection assay in human liver-derived HepG2 cells, but not in human embryonic kidney (HEK) 293 cells. FXR-binding activity was required for bile acid repression of CYP7A1 transcription despite the fact that FXR did not bind to the CYP7A1 promoter. FXR-induced liver-specific factors must be required for mediating bile acid repression. Bile acids and FXR repressed endogenous CYP7A1 but stimulated alpha-fetoprotein transcription factor (FTF) and small heterodimer partner (SHP) mRNA expression in HepG2 cells. Feeding of rats with chenodeoxycholic acid repressed CYP7A1, induced FTF, but had no effect on SHP mRNA expression in the liver. FTF strongly repressed CYP7A1 transcription in a dose-dependent manner, and SHP further inhibited CYP7A1 in HepG2 cells, but not in HEK 293 cells. FXR only moderately stimulated SHP transcription, whereas FTF strongly inhibited SHP transcription in HepG2 cells. Results revealed that FTF was a dominant negative factor that was induced by bile acid-activated FXR to inhibit both CYP7A1 and SHP transcription. Differential regulation of FTF and SHP expression by bile acids may explain the wide variation in CYP7A1 expression and the rate of bile acid synthesis and regulation in different species.

Animals↗

PubMed2001

Cyp17 promoter variant associated with prostate cancer aggressiveness in African Americans.

Androgens play an important role in the etiology of prostate cancer. The CYP17 gene encodes the cytochrome P450c17alpha enzyme, which is the rate-limiting enzyme in androgen biosynthesis. A T to C polymorphism in the 5' promoter region has recently been associated with prostate cancer. However, contradictory data exists concerning the risk allele. To investigate further the involvement of the CYP17 variant with prostate cancer, we typed the polymorphism in three different populations and evaluated its association with prostate cancer and clinical presentation in African Americans. We genotyped the CYP17 polymorphism in Nigerian (n = 56), European-American (n = 74), and African-American (n = 111) healthy male volunteers, along with African-American men affected with prostate cancer (n = 71), using pyrosequencing. Genotype and allele frequencies did not differ significantly across the different control populations. African-American men with the CC CYP17 genotype had an increased risk of prostate cancer (odds ratio, 2.8; 95% confidence interval, 1.0-7.4) compared with those with the TT genotype. A similar trend was observed between the homozygous variant genotype in African-American prostate cancer patients and clinical presentation. The CC genotype was significantly associated with higher grade and stage of prostate cancer (odds ratio, 7.1; 95% confidence interval, 1.4-36.1). The risk did not differ significantly by family history or age. Our results suggest that the C allele of the CYP17 polymorphism is significantly associated with increased prostate cancer risk and clinically advanced disease in African Americans.

Adult↗

PubMed2001

[X-ray and clinical characteristics in sagittal fracture of the mandibular condyle].

OBJECTIVE: To study the X-ray and clinical characteristics in sagittal fracture of the mandibular condyle (SFMC). METHODS: 14 cases (15 sides) of SFMC in 48 cases who had condylar fractures were studied in the research, every patient was examined by the conventional x-ray, 2D-CT and 3D-CT, and followed up for 3-39 months. RESULTS: The fracture line mainly passed through lateral 1/3 and middle 1/3 of anterior condyle and the middle 1/3 of posterior condyle. Following-up (3-39 months) showed that the patients' occlusions were normal in all cases. CONCLUSIONS: The fracture line mainly located in the lateral pterygoid muscle fossa. Good results can be gotten by effective treatment. The 2D-CT and 3D-CT are valuable to the diagnosis.

Adolescent↗

PubMed2001

Estimating historical respirable crystalline silica exposures for Chinese pottery workers and iron/copper, tin, and tungsten miners.

Collaborative studies of Chinese workers, using over four decades of dust monitoring data, are being conducted by the National Institute for Occupational Safety and Health (NIOSH) and Tongji Medical University in China. The goal of these projects is to establish exposure-response relationships for the development of diseases such as silicosis or lung cancer in cohorts of pottery and mine workers. It is necessary to convert Chinese dust measurements to respirable silica measurements in order to make results from the Chinese data comparable to other results in the literature. This article describes the development of conversion factors and estimates of historical respirable crystalline silica exposure for Chinese workers. Ambient total dust concentrations (n>17000) and crystalline silica concentrations (n=347) in bulk dust were first gathered from historical industrial hygiene records. Analysis of the silica content in historical bulk samples revealed no trend from 1950 up to the present. During 1988-1989, side-by-side airborne dust samples (n=143 pairs) were collected using nylon cyclones and traditional Chinese samplers in 20 metal mines and nine pottery factories in China. These data were used to establish conversion factors between respirable crystalline silica concentrations and Chinese total dust concentrations. Based on the analysis of the available evidence, conversion factors derived from the 1988-1989 sampling campaign are assumed to apply to other time periods in this paper. The conversion factors were estimated to be 0.0143 for iron/copper, 0.0355 for pottery factories, 0.0429 for tin mines, and 0.0861 for tungsten mines. Conversion factors for individual facilities within each industry were also calculated. Analysis of variance revealed that mean conversion factors are significantly different among facilities within the iron/copper industry and within the pottery industry. The relative merits of using facility-specific conversion factors, industry-wide conversion factors, or a weighted average of the two are discussed. The exposure matrix of the historical Chinese total dust concentrations was multiplied by these conversion factors to obtain an exposure matrix of historical respirable crystalline silica concentrations.

Air Pollutants, Occupational↗

PubMed2001

[Introduction to Go! Poly, a human genome polymorphism database].

Databases play an important role in the study of genetic polymorphism. To meet the need for more studies of human genome polymorphism by Chinese medical and pharmaceutical community, a gene oriented human genome polymorphism database-Go! Poly was constructed. As a generalized polymorphism database, Go! Poly extracted human gene-linked sequence variations of all common types from various public resources including scientific journals and Web resources such as HGBASE (http://hgbase.cgr.ki.se) and dbSNP (http://www.ncbi.nlm.nih.gov/SNP/). The polymorphism data were then categorized into different gene loci, and the reference sequences given by LocusLink were used as positioning reference. To facilitate the use, a friendly web interface and a text based query strategy were implemented. Users can fetch specific polymorphism data in just three steps: find specific gene locus by simple search, display sequence variation information of a specific gene locus select, and view the final result of a specific variation site. Besides, a web-based submission tool is provided for direct submission, which can make the polymorphism information generated by the Chinese scientific community available from this resource.

China↗

PubMed2001

[Pathological study of extracorporeally ablated hepatocellular carcinoma with high-intensity focused ultrasound].

OBJECTIVE: To investigate the pathological changes of hepatocellular carcinoma (HCC) after extracorporeal ablation with high-intensity focused ultrasound (HIFU). METHODS: A total of 56 patients with HCC was treated with HIFU. Of the 56 patients treated, 6 underwent surgical resection of the tumor 5 to 18 days following HIFU treatment The resected specimens were examined under light and electron microscope. RESULTS: Light microscope examination showed clear boundary between the treated and untreated area. Outside of the boundary the hepatic parenchyma was almost normal. In the treated area, all tumor cells appeared irreversibly dead in the forms of nuclear pyknosis, debris, and dissolution. The blood sinusoids were collapsing with endothelial cell damage. Granulation tissue was formed with the presence of immature fibroblasts and new capillaries in the boundary region between treated and untreated area. Eighteen days after HIFU treatment, the ultrasound damaged area was partially replaced by the proliferative repair tissue. Electronic microscopic examination showed the distorted tumor cells with severe destruction of cell organelles and nuclei. The cytoplasm was irregularly vesiculated, and the membranes of the organelles were broken. Cell membrane and nuclear membrane disintegration, as well as nucleus disruption were generally observed. CONCLUSION: Extracorporeal treatment of HCC with HIFU proved safe, effective, and feasible. This modality could potentially provide a new and noninvasive therapy for HCC.

Carcinoma, Hepatocellular↗

PubMed2001

[Effect of fibrinogen on corrosion behavior of stainless steel in artificial blood solution].

The effect of fibrinogen on corrosion behavior of SUS316L and SUS317L stainless steel in artificial blood PBS solution has been investigated with electrochemical technology. The results showed that the corrosion potential (Ec) of stainless steel shifted negatively, the passivated current (ip) became less and the pitting corrosion potential (Eb) shifted negatively with the existence of fibrinogen in PBS. These indicate that samples become more sensitive to corrosion under this circumstance. SEM pictures demonstrated that stainless steel adsorbed fibrinogen on its surface.

Adsorption↗

PubMed2001

Comparison of the effects of two types of intraocular lens.

OBJECTIVE: To evaluate the effectiveness and safety of implantation of flexible open-loop anterior chamber intraocular lens (FOAC-IOLs) and scleral fixated posterior chamber intraocular lens (PC-IOLs). METHODS: Sixty-eight eyes of 68 patients with implanted intraocular lenses in the absence of posterior capsular support were reviewed retrospectively. According to the type of intraocular lens, patients were classified into two groups. In group I (30 eyes), FOAC-IOLs was implanted primarily or secondarily. In group II (38 eyes), scleral fixated PC-IOLs was implanted primarily or secondarily. By gonioscopy and ultrasound biomicroscopy (UBM), accurate positions of IOLs' haptics and the relationship between the haptics and surrounding tissues were observed postoperatively and used to evaluate the influence of the two types of IOLs on ocular anterior segments. Follow-up was 6 to 20 months. RESULTS: Best corrected visual acuity of 20/40 or better was achieved in 27 eyes (90.0%) in group I, and 35 eyes (92.1%) in group II and the difference was not statistically significant (P > 0.05). In group I, 23 eyes (76.7%) had a total of 40 complications, while 13 eyes (34.2%) had 19 complications in group II (P < 0.05). Gonioscopy and ultrasound biomicroscopy showed that in group I, all haptics of IOLs contacted with the iris completely and compressed the iris to different degrees, sometimes causing the anterior chamber angles to widen. Anterior synechia of the iris was caused by the haptics of FOAC-IOLs in 12 eyes. Among the 60 IOLs haptics, 39 foot plates of the haptics were properly fixed at the ciliary band; 21 haptics (12 eyes) penetrated through the iris into the stroma of the ciliary body with accompanying recurrent uveitis. In group II, among the 76 IOLs haptics, 52 were adequately fixed in the ciliary sulcus regions, and 8 (8 eyes) were placed below the iris, causing goniosynechia. This type of angle closure was localized, with an open angle on each side of the haptics. The remaining 16 haptics were fixed onto the ciliary crown. CONCLUSIONS: The current sutured mode of scleral fixated PC-IOLs can not ensure that IOLs haptics are placed in the ciliary sulcus. The haptics of FOAC-IOLs compress the iris and may penetrate through the iris into the stroma of the ciliary body. This can cause peripheral iris anterior synechia and chronic recurrent uveitis. The implantation of scleral fixated PC-IOLs is safer and shows better effects than that of FOAC-IOLs.

Aged↗

PubMed2001

[Appraisal of renal failure reversing therapies in lupus nephritis].

OBJECTIVE: This study aimed to explore the therapies of reversing renal failure in lupus nephritis. METHODS: The research strategy was a retrospective cohort study. 173 patients were included in the study. All of them were consecutive in-patients of newly diagnosed renal failure (serum creatinine > 180 micromol/L) with lupus nephritis from 1991 to 1999 in the university hospital. The research factors included steroids, cyclophosphamide and cyclosporin. Steroids were divided to oral prednisone, intravenous dexamethasone and intravenous methylprednisolone pulse; cyclophosphamide dose intensity was divided into three grades: none, low dose (average dose 0.25 g/m(2) body surface area per week). 51 demographic, clinical and laboratory data were included in the study as possible confounding factors. The study end-point was recovery of renal function that was defined as a level of serum creatinine <or= 116 micromol/L in the azotemia patients or a 50% reduction of serum creatinine and discontinuation of dialysis in the uremic patients. The improvement had to be maintained for at least three months. Collection of the study factors and outcome variable was conducted by two separate, blinded groups of clinical specialists with two structured abstracting forms. RESULTS: The number of complete following up patients was 142 (82.1%). After over 6 months of following up, 93 cases (65.5%) recovered their renal function and 17 cases (12.0%) died. In COX proportional hazard regression model, cyclophosphamide therapy was significantly associated with the recovery of renal function. The adjusted hazard ratio (HR) to recovery of renal function was 4.41, 95% CI = 1.03 - 18.94 in low dose; and the HR was 13.29, 95% CI = 3.11 - 56.82 in high dose cyclophosphamide therapy. The gender, duration of renal dysfunction, small renal size, severe anemia and serum creatinine were also significantly associated with renal function recovery. Cyclophosphamide therapy was not significantly associated with death. The variables associated with death were low level of serum albumin and edema. CONCLUSION: Cyclophosphamide pulse was an efficient therapy in reversing renal failure of lupus nephritis, especially in the patients with short duration of renal failure, non-small in renal size, and non-severe anemia.

Administration, Oral↗

PubMed2001

[Cardio-pulmonary pathology of sudden death in asthma].

OBJECTIVE: To elucidate the pathological characteristics of the heart and lung in asthmatics with sudden death. METHOD: A detail analysis of pathological data was performed on 14 patients with sudden death in asthma. RESULTS: There was no apparent gender difference among 14 patients. 9 patients were younger than 30 years old. Pathological examination showed that bronchial infiltration of eosinophils in 14 patient (100%), thickened basement membrane of the bronchial mucosa in 12 patients (85.7%), proliferation of smooth muscle cells in 11 patients (78.6%), proliferative mucous gland in 9 patients (64.3%), mucous plug in bronchiole in 8 patients (57.1%), and cicatvization of left ventricle in 10 patients (71.4%). CONCLUSION: Severe nonspecific airway inflammation is demonstrated in asthmatic patients with sudden death. Lesions of the left ventricle and mucous plug in bronchiole may contribute to the main cause leading sudden death.

Adolescent↗

PubMed2001

[The influence of flexible open-loop anterior chamber intraocular lens on the structure of ocular anterior segment].

OBJECTIVE: To evaluate the therapeutic effects and safety of flexible open-loop anterior chamber intraocular lens (FOAC-IOL). METHODS: By ultrasound biomicroscopy, the positions of the haptics of FOAC-IOL in 20 patients (20 eyes) and the relationships of the haptics with iris and anterior chamber angle structures were observed postoperatively to evaluate the impact of these lenses on the structures of ocular anterior segment. Follow-up duration was from 6 to 20 months. RESULTS: Among 40 IOL's haptics, twenty-six haptics were fixed at the recess of the chamber angle; and other fourteen haptics penetrated the iris and invaded into the ciliary stroma, which caused recurrent uveitis. There was 1 eye with eccentric lens. There were 8 eyes with anterior synechiae of iris, which were related to the haptics of intraocular lens. CONCLUSIONS: Ultrasound biomicroscopy works well in dynamic observation of the influence of intraocular lens on ocular anterior segment. The haptics of flexible open-loop anterior chamber intraocular lens should be modified.

Aged↗

PubMed2001

[Clinicopathological significance of grading on thymic epithelial tumors].

OBJECTIVE: To study the clinicopathologic relevance of a thymic epithelial tumor (TET) grading standard with the WHO classification. METHODS: A grading system for TET was proposed based on the application of WHO histological typing of thymic tumors and analyzed in relation to clinical therapy results and follow-up data of 200 TET cases. RESULTS: In this series, 8 patients (4.0%) belonged to type A, 68 (34.0%) were type AB, 17 (8.5%) were type B1, 39 (19.5%) were type B2, 27 (13.5%) were type B3 and 36 (18.0%) were type C. The remaining 5 cases were rare thymomas. The overall postoperative survival data showed highly significant differences among the histological subtypes (P < 0.001). Type A & type AB thymomas showed excellent prognosis, none of these patients died of tumor; in type B1, only 1 case (5.9%) died at 22 months postoperatively. Types B2, B3 and C thymomas shared the bad, worse and worst prognosis. Ninety-six patients (48.0%) were in stage I, 26 (13.0%) in stage II, 65 (32.5%) in stage III and 13 (6.5%) in stage IV. Clinical stage is also highly significant in predicting survival (P < 0.001). It was found that tumor histology could predict survival expectancies well in stage I and stage II cases. It was also found that type B2, B3 and C thymomas had a statistically significant worse prognosis than type A, AB and B1 thymomas (P < 0.001). According to the histology, clinical data, biological behavior and prognosis, it is proposed that thymomas be divided into 4 grades: grade I, II, III and IV. Follow-up is the best strategy for grade I & II patients after radical surgery. In this series, the 30 patients (15.0%) presenting clinical signs of myasthenia gravis were mostly in type B2 and B3 groups (P < 0.01). CONCLUSIONS: The WHO classification for TET provides good pathological definitions and criteria for diagnosis, which can independently predict the invasiveness and prognosis of TET. TET grading is of use in unifying pathological and clinical findings, in selection of proper therapy and in predicting prognosis.

Adolescent↗

PubMed2001

[Identification of the genome of a picornavirus isolate using Random-PCR].

OBJECTIVE: To identify the genome of an enterovirus isolate (XJ90). METHODS: The double-stranded cDNA of isolated virus was synthesized with anchored-random primer and was amplified with anchor primer; the PCR products were cloned into pGEM-T vector for sequencing and analysis. RESULTS: Analysis on agarose gel electrophoresis of the Random-PCR products showed a typical smear; 11 randomly selected clones were all homologous to the members of enteroviruses and the homology rate over 80%; the 11 clones were distributed evenly along the whole genome and they assembled 4 contigs totally 2 261 bp long which covered 30% of the genome. The homology of the fourth contig and coxsackie virus B6 was 97.3% at amino acids level. The virus gene was specifically amplified with primers derived from the sequenced clones. CONCLUSIONS: The picornavirus isolate XJ90 is a member of enteroviruses.

Amino Acid Sequence↗

PubMed2001

Trace gas absorption spectroscopy using laser difference-frequency spectrometer for environmental application.

A widely tunable infrared spectrometer based on difference frequency generation (DFG) has been developed for organic trace gas detection by laser absorption spectroscopy. On-line measurements of concentration of various hydrocarbons, such as acetylene, benzene, and ethylene, were investigated using high-resolution DFG trace gas spectroscopy for highly sensitive detection.

Acetylene↗

PubMed2001

[Detection of TTV DNA from high background nuclear acid samples using specific nuclear acid captured-polymerase chain reaction].

OBJECTIVE: To improve the amplification of non-specificity of TTV DNA detection using PCR from high background nuclear acids because of its low level in samples. METHODS: Specific nuclear acid captured PCR(SNAC-PCR) was established through capturing TTV DNA onto microplate with specific nuclear acid by means of avidin-biotin system, then amplifying captured TTV DNA as usual. Its specificity was evaluated by comparing with the detection of routine extraction samples using nested-PCR with or without subsequent DNA sequencing in 10 samples of sera and liver tissues in pairs. RESULTS: Positive results were obtained using routine protocol in 4 and 9 out of 10 samples of the sera and the liver tissues respectively. The PCR products were proved to be specific using RFLP analysis with Kpn I. However, positive results were found in only 2/10 and 3/10 of samples of sera and liver tissue using DNA sequencing. The results of SNAC-PCR were the same as those of routine protocol with subsequent DNA sequencing. Furthermore, sharper electrophoresis bands were obtained. CONCLUSION: SNAC-PCR could dramatically increase the specificity of the detection of TTV DNA, especially in high background nuclear acid samples. It can be widely used in the detection of other pathogens with low seral level or in high background nuclear acid samples. The level of TTV infection might be over-evaluated by currently used TTV DNA detection when the PCR products were not confirmed by DNA sequencing.

Base Sequence↗