Search PubMed⌕ Search

Biomedical subjects

Wei Chen

Publications and source records attributed to Wei Chen.

At least 523 records · Page 29Linked to original sources

[Study of a new technique on the prevention of Oncomelania hupensis snail dispersal in the irrigation schemes in middle reaches of Yangtze River].

OBJECTIVE: To explore a new technique to prevent the dispersal of Oncomelania hupensis snail through leading flood for irrigation by floodgate in irrigation schemes. METHODS: Hydromechanical and biological were applied and to combine laboratory experiment with the field observation to form a new multidisciplinary regarding snail biological hydraulics and technical line. Findings including characteristics of hydraulics and biomechanics and move regulation etc. Physics parameter of snails were used to design and construct as well as to exam the effect of facilities and rebuilt floodgate which could prevent the snail dispersal. RESULTS: Through five years efforts, the major achievements were found as: 1) the method in testing the special gravity of snail and snail eggs was determined. 2) the special gravity of snail was (1.8 +/- 0.01) g/cm(3) and special gravity snail eggs was (2.29 +/- 0.01) g/cm(3); the classification method and classified criterion of snail size were made based on geometrical characteristics of snail shell. Six special values indicating dropping and start speed of snail in running water were obtained; Five practical formula of snail dropping and start in water were established; threshold value and movement characteristics in water were observed and tested and move mechanism of snail dispersal in water was also clarified. Based on the findings from fundamental research, the facilities of "precipitation pool for snail" and "leading water from middle level of water body" that could prevent snail dispersal were designed and rebuilt in the endemic area. Through examination to these facilities, the rate of precipitating and blocking of snails reached 100%. CONCLUSION: The achievement of the study provided reliable theoretical basis for the rebuilt of floodgate and to development of models that could prevent the dispersal of snail effectively.

Agriculture↗

[Characteristics and effect of three transforming growth factor-beta isoforms and their receptor(I) on scar formation].

OBJECTIVE: To observe the differences in protein contents of three transforming growth factor-beta (TGF-beta) isoforms, beta 1, beta 2, beta 3 and their receptor(I) in hypertrophic scar and normal skin and to explore their influence on scar formation. METHODS: Eight cases of hypertrophic scar and their corresponding normal skin were detected to compare the expression and distribution of TGF-beta 1, beta 2, beta 3 and receptor(I) with immunohistochemistry and common pathological methods. RESULTS: Positive signals of TGF-beta 1, beta 2, and beta 3 could all be detected in normal skin, mainly in the cytoplasm and extracellular matrix of epidermal cells; in addition, those factors could also be found in interfollicular keratinocytes and sweat gland cells; and the positive particles of TGF-beta R(I) were mostly located in the membrane of keratinocytes and some fibroblasts. In hypertrophic scar, TGF-beta 1 and beta 3 could be detected in epidermal basal cells; TGF-beta 2 chiefly distributed in epidermal cells and some fibroblast cells; the protein contents of TGF-beta 1 and beta 3 were significantly lower than that of normal skin, while the change of TGF-beta 2 content was undistinguished when compared with normal skin. In two kinds of tissues, the distribution and the content of TGF-beta R(I) had no obviously difference. CONCLUSION: The different expression and distribution of TGF-beta 1, beta 2 and beta 3 between hypertrophic scar and normal skin may be associated with the mechanism controlling scar formation, in which the role of the TGF-beta R (I) and downstream signal factors need to be further studied.

Adolescent↗

[Modification of Chinese hamster ovary cells].

Chinese hamster ovary cells (CHO) are preferable to prokaryotic, yeast or insect cells as hosts for biopharmaceutical production due to the products are more similar to their natural conformation. However, CHO cells confront tremendous difficulties when cultured in large scale such as mal-adaptation to serum-free medium, apoptosis and over-growth without limitation. So in addition to optimizing CHO system in respect of medium, environment and expression vector, modification of CHO cells themselves has drawn more and more attention. Here the main progress in CHO-modification is reviewed.

Animals↗

[Molecular cloning and expression of the immunodominant protein Ag85A from Mycobacterium tuberculosis H37Rv strain].

OBJECTIVE: To provide the target gene and target antigen for the development of new vaccine against tuberculosis. METHODS: According to the gene sequence encoding protein Ag85A from Mycobacterium tuberculosis H37Rv strain, we designed a pair of oligonucleotide primers, obtained the gene by using polymerase chain reaction, and inserted the gene into the BamH I and EcoR I site of plasmid pBK-CMV to construct recombinant plasmid, and after that, the recombinant plasmid was transferred into E. coli XL1-Blue MRF' and induced with IPTG. The expression product of the gene was analyzed by using SDS-PAGE and western-blotting. RESULTS: The gene encoding the protein Ag85A of Mycobacterium tuberculosis H37Rv strain was successfully amplified by using PCR. A recombinant shuttle plasmid was constructed. The recombinant plasmid stably expressed recombinant Ag85A protein relative molecular mass 32 x 10(3) in E. coli XL1-Blue MRF'. CONCLUSION: A recombinant plasmid which contains the gene encoding the protein Ag85A of Mycobacterium tuberculosis H37Rv strain has been successfully constructed. The recombinant plasmid can stably express recombinant protein relative molecular mass 32 x 10(3) in E. coli XL1-Blue MRF'. These results could serve as a basis for further studies on the usefulness of the gene and its expression product in the development of new vaccine against tuberculosis.

Acyltransferases↗

[Research on preparation of mycobacterium tuberculosis DNA microarray].

OBJECTIVE: To optimize and develop the technique for mycobacterium tuberculosis DNA microarray. METHODS: The process included preparation of DNA samples, spotting and past-spotting treatment of arrays. DNA microarrays were prepared by spotting fluorescence labeled PCR products of target genes onto specially treated glass slides with robotics. The fluorescent signals before and after treatment were scanned with a scanner, and the DNA attachment rate was calculated from the obtained data by software. RESULTS: A foundation for optimizing the conditions of Mycobacterium tuberculosis DNA microarrays has been laid. The support aldehyde-modified glass slide is useful for anchoring DNA at Some distance. DMSO as spotting solution is of benefit to preparation of Mycobacterium tuberculosis DNA microarray. Drying the chip at 37 degrees C temperature after spotting can enhance the DNA combination rate. CONCLUSION: Several key steps of this technique have been optimized. This study has provided a foundation for optimizing the DNA attachment conditions in creating mycobacterium tuberculosis DNA microarray.

DNA, Bacterial↗

[Detection of crystal polymorphs of nateglinide by DSC].

AIM: To establish the differential scanning calorimetric (DSC) methodology for controlling the crystal-type B form of nateglinide. METHODS: Accurately weighed pure dried (P2O5 as desiccant for 4 h at 80 degrees C in vacuum) fine powder of crystal-type B and H of nateglinide were measured dQ/dT by DSC at heating rate of 10 degrees C. min-1 and temperature between 100 degrees C and 200 degrees C to calculate the enthalpy delta HB and delta HH. Accurately weight a series of uniform mixtures of crystal-type B and H of dried fine powder of nateglinide in different proportions. The enthalpy of the mixtures is measured by DSC as above to calculate the enthalpy (sigma delta H). Using B% as X, sigma delta H as Y, the regression equation was obtained. According to this equation, the unknown composition of mixed crystal was evaluated by the sigma delta H values. The method was used to control the limitation of crystal-type B of nateglinide by the sigma delta H value of mixture of known composition as reference. RESULTS: The results measured from different laboratories showed that the repeatability was 0.61% and the recoveries were 86.2%-127% when the amounts of crystal-type B were between 0-15%. CONCLUSION: This method can be used to evaluate the crystal-type B composition of nateglinide.

Calorimetry, Differential Scanning↗

[Construction and identification of recombinant shuttle-plasmid with ESAT-6 from Mycobacterium tuberculosis].

OBJECTIVE: To construct a recombinant BCG secretively expressing ESAT-6 of Mycobacterium tuberculosis. METHODS: alpha-antigen(alpha-Ag) signal sequence and esat-6 gene were amplified from the genome of Bacille Calmette-Guerin (BCG) and Mycobacterium tuberculosis by PCR respectively. esat-6 gene was cloned in E. coli-BCG shuttle-plasmid pMV261 to get pME. Then a new recombinant plasmid pSME was constructed by inserting BCG alpha-Ag signal sequence into pME. RESULTS: The cloned genes alpha-Ag signal sequence and esat-6 were correctly inserted into the vector pMV261, which was confirmed by restriction endonuclease digestion and PCR amplification of pSME. CONCLUSION: pSME was expected to secretively express ESAT-6 of Mycobacterium tuberculosis in BCG. This study provides the possibility of further researches on the development of new anti-tuberculosis vaccine.

Animals↗

Vascular and biliary complications after liver transplantation: interventional treatment.

OBJECTIVE: To evaluate the value of angiography and cholangiography on the diagnosis and interventional treatment of vascular and biliary complications after liver transplantation. METHODS: Sixteen of 46 patients (15 men and 1 woman, 17 - 60 years old) after orthotopic liver transplantation received angiography due to abnormal ultrasonography or edema of lower limbs, or cholangiography due to progressing jaundice. Percutaneous transluminal angioplasty or drainage was performed in some patients. RESULTS: Fifteen patients experienced vascular complications and 4 patients had biliary complications. Three of them appeared to have both vascular and biliary complications. Hepatic artery complications were the most common complications (9/16), including hepatic artery thrombosis or stenosis (6/9), bleeding (2/9) and hepatic artery-dissecting aneurysm (1/9). One patient with hepatic artery thrombosis received transcatheter thrombolysis and two patients with bleeding received coil embolization. Inferior vena cava and portal vein stenosis were observed in 6 and 2 patients, respectively. After balloon angioplasty or stent placement, clinical symptoms were alleviated. Biliary complications, including biliary stricture and anastomotic bile leak, occurred in 4 patients. Jaundice decreased after percutaneous transhepatic cholangiography and drainage. CONCLUSIONS: Besides diagnosis, interventional methods include mini-invasive treatment for patients with vascular and biliary complications after liver transplantation. Balloon angiography and stent placement for venous stenosis are useful procedure for the treatment of these problems.

Adolescent↗

[Basic theory and research method of urban forest ecology].

With the development of world economy and the increment of urban population, the urban environment problem hinders the urban sustainable development. Now, more and more people realized the importance of urban forests in improving the quality of urban ecology. Therefore, a new subject, urban forest ecology, and correlative new concept frame in the field formed. The theoretic foundation of urban forest ecology derived from the mutual combination of theory relating to forest ecology, landscape ecology, landscape architecture ecology and anthrop-ecology. People survey the development of city from the view of ecosystem, and regard the environment, a colony of human, animals and plants, as main factors of the system. The paper introduces systematically the urban forest ecology as follows: 1) the basic concept of urban forest ecology; 2) the meaning of urban forest ecology; 3) the basic principle and theoretic base of urban forest ecology; 4) the research method of urban forest ecology; 5) the developmental expectation of urban forest ecology.

City Planning↗

The construction and expression of recombinant shuttle plasmid with OmpL1 gene from leptospira interrogans serovar Lai strain 017 in Bacille Calmette-Guerin.

OBJECTIVE: To construct recombinant BCG against leptospirosis. METHODS: We amplified the entire open reading frame of the OmpL1 gene from the genome of the leptospire serovar Lai strain 017. Two recombinant plasmids pBQ1 and pBQ2 were constructed by oriented ligation based on the E. coli-BCG shuttle plasmids pMV261 and pMV361 respectively. The recombinant plasmids were transformed into BCG by electroporation. The rBCGs bearing pBQ1 and pBQ2 were induced by high temperature of 45 degrees C. RESULTS: The expressed product, a 35kD protein was detected by SDS-PAGE. The result indicates that pBQ1 and pBQ2 can express OmpL1 in rBCG. CONCLUSION: The technical methods in this study may help detect the immunogenicity and immunoprotection of OmpL1 and develop more safe, highly effective rBCG bearing leptospiral antigen with long-lasting protection.

BCG Vaccine↗

[Spectral analysis in nanometer material science].

Spectral analysis is an important means in studies of nanometer scale systems, and is essential for deep understanding the structure and properties of nanometer materials. This paper reviews the recent progresses made in studies of nanometer materials using spectral analysis methods such as UV-Visible spectroscopy, FTIR spectroscopy, Raman spectroscopy, Mössbauer spectroscopy, positron annihilation and photoacoustic spectroscopy. The principle, characteristics and applications of most frequently employed spectral methods are introduced briefly and illustrated with typical examples. Future perspectives of spectral analysis in nanometer field are discussed. New directions of establishing spectral analysis methods at nanometer scale resolution and developing new spectroscopy technology in nanometer material studies are also emphasized.

Nanotechnology↗

[A comparative study on clinical effectiveness of activator and Headgear-Activator].

OBJECTIVES: Compare the effects of Activator and Headgear-Activator on growing patients with Class II malocclusion. METHODS: The material consisted of 36 pairs of cephalograms, among which 12 cases were treated with Activator, 17 cases with Headgear-Activator and 9 cases without treatment for control. A reference grid was created to evaluate the skeletal and dental changes quantitatively. RESULTS: Activator and Headgear-Activator were effective on the correction of Class II malocclusion, but the mechanisms were different. CONCLUSION: Both appliances were effective on the correction of skeletal Class II malocclusion of growing patients. By using the headgear, the inhabitation of forward and downward growth of the maxilla was enhanced, and the dental-alveolar changes different from Activator treatment benefit for the improvement of the dental facial appearance of the patient.

English Abstract↗

[Quantitative assessment to the effect of HGAC treatments].

OBJECTIVE: To evaluate the treatment effect of skeletal class II malocclusion with HGAC. METHODS: Seventeen skeletal Class II cases were selected and treated with HGAC, pre-treatment and post-treatment cephalometric radiographs were analyzed by Pancherz analysis. RESULTS: Maxillary growth was inhibited by HGAC, especially in vertical direction. Mandibular retrognathism was improved significantly in horizontal direction. Meanwhile, the upper incisors were retruded and intruded. CONCLUSION: HGAC was effective in the correction of skeletal class II malocclusion.

English Abstract↗

G protein-coupled receptor kinase 5 regulates beta 1-adrenergic receptor association with PSD-95.

We previously reported that the beta(1)-adrenergic receptor (beta(1)AR) associates with PSD-95 through a PDZ domain-mediated interaction, by which PSD-95 modulates beta(1)AR function and facilitates the physical association of beta(1)AR with other synaptic proteins such as N-methyl-d-aspartate receptors. Here we demonstrate that beta(1)AR association with PSD-95 is regulated by G protein-coupled receptor kinase 5 (GRK5). When beta(1)AR and PSD-95 were coexpressed with either GRK2 or GRK5 in COS-7 cells, GRK5 alone dramatically decreased the association of beta(1)AR with PSD-95, although GRK2 and GRK5 both could be co-immunoprecipitated with beta(1)AR and both could enhance receptor phosphorylation in vivo. Increasing expression of GRK5 in the cells led to further decreased beta(1)AR association with PSD-95. Stimulation with the beta(1)AR agonist isoproterenol further decreased PSD-95 binding to beta(1)AR. In addition, GRK5 protein kinase activity was required for this regulatory effect since a kinase-inactive GRK5 mutant had no effect on PSD-95 binding to beta(1)AR. Moreover, the regulatory effect of GRK5 on beta(1)AR association with PSD-95 was observed only when GRK5 was expressed together with the receptor, but not when GRK5 was coexpressed with PSD-95. Thus, we propose that GRK5 regulates beta(1)AR association with PSD-95 through phosphorylation of beta(1)AR. Regulation of protein association through receptor phosphorylation may be a general mechanism used by G protein-coupled receptors that associate via PDZ domain-mediated protein/protein interactions.

Adrenergic beta-Agonists↗

Sonochemical Processes and Formation of Gold Nanoparticles within Pores of Mesoporous Silica.

Mesoporous silica with gold nanoparticles inside its pores was prepared by the soaking and ultrasound-induced reduction method. This new composite was characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and high-resolution transmission electron microscopy (HRTEM) techniques. The results showed that nearly spherical-shaped gold nanoparticles, with mean size in diameter of 5.2 nm, are located in the pores, most of which are less than 6 nm in diameter. The ultrasonic irradiation time dependence of optical absorption for the soaked porous solid sample, as suggested by the variation in absorbance at 310 and 544 nm, indicated the reduction of Au (III) ions, and the nucleation and aggregation of gold nanoparticles within pores of mesoporous silica. Additionally, the reaction rates estimated phenomenologically by the absorbance decay at 310 nm for both the porous sample and the corresponding soaking solution presented the enhancement of the sonochemical reduction rate of Au (III) ions within pores of mesoporous silica. It is assumed that the extensive liquid-solid interfacial zones in the pores, due to the high specific surface areas and great porosity of the mesoporous solid, are the major regions where the efficient sonochemical reduction induced by the cavitation takes place. Copyright 2001 Academic Press.

Journal Article↗

Ground-State Properties and Excited-State Reactivity of 8-Quinolate Complexes of Ruthenium(II).

In an effort to explore new systems with highly reducing excited states, we prepared a series of Ru(II) complexes of the type Ru(L)(2)quo(+) (L = bpy (2,2'-bipyridine), phen (1,10-phenanthroline), dmphen (4,7-dimethyl-1,10-phenanthroline), tmphen (3,4,7,8-tetramethyl-1,10-phenanthroline); quo(-) = 8-quinolate) and investigated their photophysical and redox properties. The absorption and emission spectra of the Ru(L)(2)quo(+) are significantly red-shifted relative to those of the parent complexes Ru(L)(3)(2+), with emission maxima in the 757-783 nm range in water. The Ru(L)(2)quo(+) systems are easily oxidized with E(1/2)(Ru(III/II)) values ranging from +0.62 to +0.70 V vs NHE, making the emissive Ru --> phen MLCT (metal-to-ligand charge transfer) excited states (E(00) approximately 1.95 eV in CH(3)CN) of the Ru(L)(2)quo(+) complexes significantly better reducing agents than the MLCT states of the parent Ru(L)(3)(2+) complexes. Emission lifetimes of 17.0 and 32.2 ns were measured for Ru(phen)(2)quo(+) in water and acetonitrile, respectively, and 11.4 ns for Ru(bpy)(2)quo(+) in water. Transient absorption results are consistent with the formation of reduced methyl viologen upon Ru(phen)(2)quo(+) excitation with visible light in water. The possibility of observing the Marcus inverted region in the forward bimolecular electron transfer reaction from the highly reducing Ru(phen)(2)quo(+) excited state was explored with neutral electron acceptors with reduction potentials ranging from +0.25 to -1.15 V vs NHE.

Journal Article↗