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Biomedical subjects

W Chen

Publications and source records attributed to W Chen.

At least 721 records · Page 40Linked to original sources
PubMed1997

[Transduction of the IL-2 gene into human gastric cancer cell: an experimental study].

We evaluated the possibility of inducing a productive transfer of the IL-2 gene into human gastic cancer cells (GCC) and assessed the phenotypic and proliferative changes generated in the nude mice. The plasmid vector (BMGNeo-IL-2) carrying the human IL-2 gene was used to transduce the SGC-7901 GCC line by the lipofectin reagent. The IL-2 gene was analyzed by Southern blot and productive IL-2 release using IL-2-dependent CTLL. Cytotoxicity of LAK cells was tested by MTT colorimetry. The kinetics of in vitro growth and proliferation of parental and engineered cells were also measured. Parental and IL-2 gene transduced GCC were injected into nude mice. The tumorigenic potential of IL-2 gene-transfected GCC was evaluated by examining their in vivo growth in nude mice. The productive insertion of the IL-2 gene was achieved in SGC-7901. The amounts of IL-2 constitutively released by the engineered neoplastic cells ranged from 20 to 131 U/ml of IL-2 produced from 10(6) cells in 24 hours. Transduction of GCC with IL-2 gene did not modify the morphology and growth rate. IL-2 gene transfected cells demonstrated increased susceptibility to cell killing by LAK cells. IL-2 producing cells lost their tumorigenicity as evidenced by failure to grow in nude mice. The results demonstrate that IL-2 gene can be productively transduced into human gastric cancer cells without modifying their morphology and growth rate and this transduction leads to reduced or abrogated in vivo tumorigenic potential.

Animals↗
PubMed1997

[Expression and distribution of bFGF in rat lung tissue of chronic hypoxic pulmonary hypertension].

OBJECTIVE: To evaluate the role of bFGF in the development of hypoxic pulmonary hypertension. METHOD: Rat models with chronic hypoxia induced pulmonary hypertension were established, the pulmonary hemodynamics were measured and the pulmonary arterioles change were studied with morphometric analysis under light microscopes, immunohistochemical staining with monoclonal antibody against human recombinant bFGF was performed in the paraffin section of rat lung. RESULT: (1) The mean pulmonary artery pressure (mPAP), and the ratio of the thickness of pulmonary arteriolar wall to external diameter of pulmonary arterioles (MT%) were 3.96 +/- 0.47 kPa and 33.8% +/- 3.5% in rats exposed to hypoxia for 3 weeks respectively, both were significant higher than those in normal control group, P < 0.01. (2) The positive staining for bFGF in the wall of pulmonary arterioles in hypoxic rats was stronger than that of control group (P < 0.01), there was a statistical relationship between increase of staining for bFGF and MT% in rats exposed to hypoxia. CONCLUSION: (1) Hypoxia can induce formation of pulmonary hypertension and structual remodeling of pulmonary arterioles. (2) bFGF may modulate the structure remodeling of pulmonary arterioles in chronic hypoxic pulmonary hypertension.

Animals↗
PubMed1997

[cDNA cloning of human stem cell factor and its high level expression in E. coli].

The total RNA of HepG2 cell was extracted as the template by ultrocentrifuge method. The full length cDNA (0.8 kb) encoding the human stem cell factor (hSCF) was amplified by RT-PCR method. The cDNA encoding mature hSCF (0.5 kb) was sequenced and was recombined into the expression vector (PBV-220). The expression level of rhSCF in E. coli DH5 alpha was about 15% of the total protein.

Amino Acid Sequence↗
PubMed1997

[Diagnostic value of pleuro-examination with fiberoptic bronchoscope in indefinite pleural effusions].

The diagnostic value of pleuro-examination with fiberoptic bronchoscope in indefinite pleural effusions was studied. Pleuro-examination with fiberoptic bronchoscope has been performed in 10 cases with indefinite pleural effusions, and its diagnostic value and complications have been observed. The results showed that the diagnoses were confirmed in 9 of 10 patients submitted to pleuro-examination, and no severe complications were found. The results suggest that pleuro-examination with fiberoptic bronchoscope is an effective and safe procedure and might be performed on patients with pleural effusions when routine examinations fail to provide a diagnosis.

Adenocarcinoma↗
PubMed1997

[Effect of tetrandrine on pulmonary vascular morphology in rats with hypoxia pulmonary hypertension].

To investigate the effect of Tetrandrine on pulmonary vascular morphology in rats with hypoxia pulmonary hypertension. We established the model of hypoxia pulmonary hypertension and observed the small pulmonary arterial morphologic changes under light microscope and electron microscope after the rats were treated with Tetrandrine; also, we made morphometric analysis. The results showed that the small pulmonary arteria in rats with hypoxia pulmonary hypertension was thinner than normal ones and had proliferation of smooth muscular cells. Morphometry displayed that the external diameter became smaller and that the ratio of vascular wall thickness to external diameter (M/T%) and the ratio of vascular wall area to total area (MA%) increased. The pathologic change significantly decreased after the rats were treated with Tetrandrine, indicating that Tetrandrine inhibited hypoxia-induced thickening and muscularization of small pulmonary arteria by inhibiting the proliferation of collagenous fibers so that narrowing of small pulmonary arteria was significantly slackened and pulmonary hypertension was alleviated. Therefore, we conclude that tetrandrine may partly prevent the development of pulmonary hypertension.

Alkaloids↗
PubMed1997

[Effect of different hypoxic duration on changes of pulmonary circulation].

In order to assess the relationship between the hypoxic duration and pulmonary hypertension, we investigated the pulmonary hemodynamics and right ventricular hypertrophy and pulmonary vascular structure changes in rats with hypoxic exposure for 1 day to 3 weeks. After hypoxic treatment, the pulmonary artery pressure of rats increased in 3 days, and it was up to peak at 2 weeks later. The weight of right ventricle of rats significantly increased after 1 week. The endothelium of pulmonary vascular of rats became swollen in 3 days, and then increased in extracellular matrix deposition. Vessel wall thickening was found in 1 week hypoxic rats, and it was very significant in 3 week hypoxic rats. The results suggest that the duration of hypoxic treatment is related to the change of pulmonary circulation in 3 weeks in rats.

Animals↗
PubMed1997

[Alkaloid production of cultured coptis cells by two-stage suspension-culture].

In this study the asexual cell line H292 induced and selected from Coptis gulinensis had rapid growth rate and could stably produce alkaloids. By the one-stage method, after the cell suspensions were cultured on the same medium for six weeks, the increased dry and fresh weights of the cells were 20.96 g/L and 174.92 g/L respectively. The content of the total alkaloids in the cells was 14.79 mg/g cell dw. Per litter liquid medium could provide 323 mg alkaloid. In contrast, the cells were cultured by two-stage method. After having been cultured on the medium which contributed to the growth of the cells for three weeks, the cells were transferred to the medium which contributed to the production of the alkaloid and cultured for three weeks. Six weeks later, the dry and fresh weights of the cells were 16.72 g/L and 127.44 g/L, respectively. The biomass was lower than that by one-stage method, but the content of the total alkaloids was as high as 31.76 mg/g cell dw, which was much more than that by one-stage method. In addition, the content of the alkaloid in the medium was 25.31 mg/L. Per litter liquid medium could provide 556 mg alkaloid. The total yield of alkaloid obtained by two-stage method was 1.72 times than that by one-stage method.

Alkaloids↗
PubMed1997

[Effects of chronic hypoxia on calmodulin activity in rats].

To investigate the effects of chronic hypoxia of calmodulin activity in rats, we divided 40 wistar rats into four major groups. One group acted as control. The other three groups were made hypoxic by placing them in an isobaric hypoxic chamber (O2 = 10%) for 1, 2 and 3 weeks respectively. Calmodulin activity was measured by Phosphodiesterase method. The results showed that the mean pulmonary arterial pressure and the pulmonary vascular resistance in rats were remarkably increased by chronic hypoxia. The total calcium levels and the calmodulin content in the lung tissue of rats were significantly elevated at 2-3 weeks of hypoxia exposure. However, the calmodulin content in the lung tissue of the rats exposed to hypoxia for 1 week also increased, but it was lower than those at 2-3 weeks of hypoxia exposure. Therefore, we conclude that Ca(2+)-calmodulin system may play a central role in mediating hypoxai-induced pulmonary hypertension.

Animals↗
PubMed1997

[Effect of methylphenidatum on inspiratory muscles function in patients with chronic obstructive pulmonary disease and its mechanism].

To have a better understanding of the effect of methylphenidatum on inspiratory muscles function, we studied the respiratory force parameters of 70 patients with chronic obstructive pulmonary disease by intravenous infusion methylphenidatum in a randomized controlled clinical trial. The indices of respiratory force parameter included maximal inspiratory mouth pressure (MIP), maximal midinspiratory flow (MMIF), forced inspiratory capacity (FIC), maximal works of inspiration (Wimax) and airway occlusion pressure (P0.1), etc. Aminophylline and Nikethamidi were chosen as controls. The results showed that MIP, MMIF, FIC, Wimax, P0.1 and minute ventilation (Vr) were significantly increased after administration of methylphenidatum and aminophylline. There were no significant differences in MIP, MMIF, FIC and Wimax after administration of Nikethamidi, but P0.1 was significantly increased and the increase was higher than that after administration of methylphenidatum and aminophylline groups. We conclude that methylphenidatum can significantly improve the function of inspiratory muscles as aminophylline can do.

Female↗
PubMed1997

[Reconstruction of laryngotracheal stenosis: experience of twenty years].

In order to improve the curative effects of laryngotracheal stenosis, 261 patients treated for laryngotracheal stenosis during the last twenty years were retrospectively reviewed. Glottic reconstruction, fence-form laryngotracheal reconstruction and laryngotracheotomy with autogenous tissue or hydroxylapatite rings were selectively used for one-stage reconstruction. Our results demonstrated that among 261 patients, 9 failed in decannulation, 5 were lost for follow-up, 247 (94.6%) patients were successfully decannulated. Among 192 patients followed-up from 1 to 18 years, 4 had restenosis 3 years after operation, 3 were successfully retreated and 10 failed. 182 (94.7%) patients had stable airways. It is concluded that there was no fixed treatment for laryngotracheal stenosis. The choice of surgical procedure and grafting must be decided on the pathologic condition of the larynx and trachea. The advantages of fence-form laryngotracheal reconstruction are simple technique and good result. Reconstruction with combined bipedicled myocutaneous flap and costal cartilage or artificial materials are better for severe laryngotracheal stenosis and large tracheal defect. The usage of stent is important for laryngotracheal reconstraction.

Adolescent↗
PubMed1997

[Long-term effects of stapes elevation].

To assess the clinical value of stapes elevation, 38 cases had been followed-up for 1-12 years (average 6.7 years). The results revealed that hearing improvement rate (over 10 dB) was 94.7% in short term and 86.8% in long term follow-up. The long term regression rate was similar to that in stapedectomy, and no severe sensorineural hearing loss occurred. In addition, the vestibular reaction was slight, especially in reoperated cases. The stapes elevation was easy to perform as compared with stapedectomy. Therefore, this technique may be the first choice for stapes surgery.

Adolescent↗
PubMed1997

[Clinical and pathological observation of recurrent nasal polyp formation].

To investigate the mechanism of nasal polyp recurrence, 19 patients with recurrent nasal polyp were retrospectively analysed. In 4 patients, nasal polyp specimens had been sent for pathological examination more than three times, and in 6 patients, bacteria culture was performed. There were two types of recurrent nasal polyp: water-cyst type (fast recurrence) and edematous granulation type (slow recurrence). Both types were the result of inflammatory reaction, perhaps related to trauma of operation. Water-cyst formation indicated stronger inflammatory reaction. During follow-up, 10 patients were cured and 9 recurred. Preventive measures against nasal polyp recurrence were discussed.

Adult↗
PubMed1997

[Effect of processing on chemical composition and medical activity of rhizoma Anemarrhenae].

A comparative study was conducted on the chemical composition and medical activity of different kinds of processed drug of Rhizoma Anemarrhenae. It was found that the content of effective components of zhimu was affected obviously by processing: the rhizome should not be barked when used as drug. It was also observed that different kind of processed drug should be used in line with different particular circumstance.

Animals↗
PubMed1997

[The effect of pH on anti-corrosion nature of amalgams].

Corrosion behavior of alloys are affected not only by themselves but also by environment, such as a change of pH. In this study, the corrosion behavior of four dental amalgams (L, C, DA, GK) in Fusayama saliva with different pH 6.65 and 4.00 are evaluated by electrochemical techniques. It seems that changes in pH may exert different effects on the four amalgams. In the acid environment DA exhibits best anti-corrosion nature and followed by GK, C, and L, which conforms to clinical observations. This may be resulted either from amalgams themselves or from conditions of corrosion products of amalgams' surface. Thus, consideration must be given to the changing oral environment when screening anti-corrosion alloys.

Corrosion↗
PubMed1997

[A study on taxonomy of Rhizobia isolated from Astragalus sp].

Thirty-six strains isolated from root nodule of Astragalus spp., in comparison with 31 reference strains of Rhizobium, Bradyrhizobium and Sinorhizobium species, and some other strains isolated from legumes in Xinjiang and Hainian Province, were classified by performing numberical taxonomy, DNA-DNA hybrization and partial 16S rRNA gene sequencing. Results of herichical analysis showed most of trains isolated from Astragalus spp. fell into subgroups 8 and 9, Also the DNA homolgy among strains of subgroups 8 and 9 are more than 70%, with the exception of strains CA8593 and SX044, and the DNA homology between strain CA8561, JL84 and type strains of all described rhizobial species are less than 56%. These results indicated that these two subgroups 8 and 9 were unique DNA homologous groups, distinguishing from all described rhizobial species. Sequencing of partial 16S rRNA gene showed that cetrostrain CA8561 of subgroup 8 is phylogenetically far from all know species of Rhizobium, Bradyrhizobium, Sinorhizobium, Azorhizobium and Agrobacterium, and it is a unique geneline. The cetrostrain JL84 of subgroup 9 has a unique position in the phylogenetic branch consisted of species of Rhizobium and Agrobacterium.

Fabaceae↗
PubMed1997

[Sequencing the 16S rDNA of representative strain of new rhizobial group and determining of its phylogenetic relationship].

The full-length 16S rDNA sequence of representative strain SH2672 were sequenced by the dideoxy-mediated chain-termination method. This sequence was compared with that of type strains of all known rhizobia and related bacteria. An unrooted phylogenetic tree was produced. In this tree, strain SH2672, Mesorhizobium loti, M. huakuii, M. tianshanense, M. mediterraneum, and M. ciceri constituted a branch. Within this branch, the similarity values of 16S rDNA sequences between strain SH2672 and M. loti, M. huakuii, M. tianshanense, M. mediterraneum and M. ciceri were 96.3%, 96.4%, 97.2%, 95.1% and 95.6% respectively. All similarity values was more than 95%, this indicated that these species should belong to the same genus. The values of DNA-DNA homology between type strains of these species were less than 70%, which showed that strain SH2672 (representative strain of new group) represented a new rhizobial species.

Base Sequence↗
PubMed1997

Expression of HBV Pre S1 peptide in E. coli and product characterization.

HBV Pre S1 sequence is supposed to play an important role in the infection of HBV. Presence of Pre S1/anti-Pre S1 in serum has valuable clinical implications. In order to improve the study of Pre S1, Pre S1 sequence was overexpressed in E. coli as a fusion protein with MBP (Maltose-binding protein), and anti-Pre S1 antiserum was elicited in rabbits by Pre S1-MBP purified by affinity chromatography. The recombinant plasmid constructed from pMAL-cRI expressed the 106aa Pre S1 sequence at the C terminal of MBP by tac promoter. The resulting protein is about 54 kD in size. Western-blot analysis confirmed its reactivity with antiserum derived from synthetic Pre S1 peptide and serum from patients with acute hepatitis B (AHB). ELISA showed that Pre S1-MBP and Dane particles purified from AHB patient's serum reacted with antiserum against synthetic Pre S1 peptide, and this reaction was specifically inhibited by synthetic Pre S1 peptide. ELISA also demonstrated that antiserum against Pre S1-MBP reacted with synthetic Pre S1 peptide, but not with synthetic HCV peptide or HEV peptide.

Escherichia coli↗