Biomedical subjects

Wei Chen

Publications and source records attributed to Wei Chen.

At least 289 records · Page 16Linked to original sources

PubMed2005

[Effects of Triton X-100 on the oxygen uptake rate of photosystem I particles treated at 70 degrees C].

The characteristics including oxygen uptake rates, fluorescence spectra and absorption spectra of photosystem I particles with or without Triton-X 100 treatment before or after the incubation at 70 degrees C for 10 min were compared. The oxygen uptake rates of photosystem I particles decreased after being incubated at 70 degrees C for 10 min, which could be recovered by the addition of Triton-X 100. Singlet oxygen was formed when the light-harvesting complex I was separated from the core complex of photosystem I, which resulted in high oxygen uptake rate. There was much difference in the fluorescence spectra of photosystem I particles between photosystem I particles treated with Triton-X 100 after the incubation at 70 degrees C for 10 min or not, which implies the ability of Triton-X 100 to promote the recovery of photosystem I particles after the incubation at 70 degrees C for 10 min.

Hot Temperature↗

PubMed2005

[Expression and analysis of biological activity of the recombination anthrax edema factor].

Anthrax toxin consists of three separate proteins, protective antigen (PA), lethal factor (LF) and edema factor (EF). EF is bacterial adenylate cyclase which, upon activation by its eukaryotic cofactor, calmodulin, causes a rapid increase in the intracellular cAMP level of host cells. EF can reduce the protective ability of host animal. In order to further research the mechanism of anthrax toxin, the expression plasmid was constructed and the structural gene for anthrax edema factor (EF) was expressed in Escherichia coli. Recombinant EF (rEF) was purified to homogeneity by a three-step procedure involving metal chelating affinity chromatography, cation-exchange chromatography and gel chromatography. From 1 liter of culture, 5mg of biologically active EF was easily purified. Rabbits were immuned with rEF, anti-EF antibodies were prepared and can neutralize rEF in cells. Tests in vitro proved rEF have good biological activity. rEF can competed the binding regions of PA with rLF in J774A.1 and CHO cells. rEF and rLF can restrain each other by competition. The successful expression of rEF has placed a solid foundation for the research on toxicity mechanism of EF, and screening for inhibitors against EF.

Adenylyl Cyclases↗

PubMed2005

[Gene knockout and knockin on the Escherichia coli lac operon loci using pBR322-red system].

pBR322-Red is a newly constructed recombineering plasmid, which contains a part of the pBR322 vector, a series of regulatory elements of lambda-prophage and Red recombination genes. In the beginning, we studied the best working conditions of pBR322-Red, and then modified lac operon in E. coli W3110 chromosome using the plasmid as follow: Firstly, we knockout the lacI gene using Red-mediated recombineering with overlapping single stranded DNA oligonucleotides. Secondly, we substituded the lacA and lacY genes with lacZ, a report gene, by Red-mediated linearized double strands DNA homologous recombination. Finally, we detected the expression of lacZ on these loci for the first time. The results suggested that pBR322-Red system is suitable for modifying W3110 chromosome with various recombination strategies.

Bacteriophage lambda↗

PubMed2005

[Development of a new recombineering system by gap repair].

Using lambda phage Red recombinase mediated in vivo homologous recombination system, a 6.7 kb lambda PL operon sequence including the Red encoding genes was subcloned into pBR322 by gap repair technique, and generated a pBR322-Red recombinant plasmid that can provide the Red recombination function and can be transferred into many kinds of bacteria. To confirm the recombination functions of pBR322-Red, a single-stranded 70-bases oligo was introduced into W3110 by electroporation to create a single base T-->G mutation in galK gene on the bacterial chromosome. The result demonstrated that a new lambda Red-mediated recombineering system based on pBR322-Red was successfully established.

Bacteriophage lambda↗

PubMed2005

[Therapy of Duchenne muscular dystrophy with umbilical cord blood stem cell transplantation].

OBJECTIVE: To analyze a Duchenne muscular dystrophy(DMD) patient's muscular regeneration, dystrophin expression and locomotive variation before and after he underwent umbilical cord blood stem cell transplantation in order to assess the therapeutic effect. METHODS: A 12-year-old DMD boy who could not walk for 3 years was confirmed by gene analysis and dystrophin protein immune test on his muscle. He had no other chronic disease. By HLA matching, a piece of umbilical cord blood stem cell with 6 HLA sites matching to the boy was found in Guangdong Umbilical Cord Blood Bank. The number of the nucleated cells of the umbilical cord blood stem cell was 24.08x 10(8). After pretreatment for the DMD boy with busulfan, cyclophosphamide and rabbit anti-human thymocyte globulin, the allergenic cord blood stem cells were transplanted into him by intravenous injection. Cyclosporin A, methylprednisolone, MMF, prostaglandin E1 and ganciclovir were given after the transplantation. At the same time, Gran, the granulocytic cell stimulating factor, and gamma globulin were administered. The biochemistry profile including serum creatine kinase (CK), the reconstruction of blood making, the deletion exon of DMD gene, the regenerating muscles, the dystrophin protein expression, and the locomotive function of the DMD boy were tested regularly. RESULTS: (1) The white blood cells (WBC) of peripheral blood decreased gradually to zero after pretreatment. In a period of 15 days after transplantation, the neutrophil increased to 0.5x 10(9)/L; at 25 days, WBC increased to normal level. Blood platelet was more than 20x 10(9)/L at 22 days. The hemoglobin rose to 85-100 g/L. At 140 days, sternal puncture revealed the rapid growth of neutrophil, blood platelet and hemoglobin. (2)At 140 days, the blood type of the DMD boy transformed from type O to type AB (the donor's blood type being AB). There was no grafe versus host reaction. (3) At 18, 30, 43, 55, 74 and 233 days after transplantation, the PCR-short tandem repeat test of the boy's peripheral blood DNA showed that his genotype was completely the same as the donor's. The results of PCR-short tandem repeat tests of the bone marrow cells DNA by sternal puncture at 140, 183 and 235 days were the same as those of the blood DNA. (4) At 60 days, DMD gene analysis by PCR showed that the defected DMD gene (exon 19 deletion) had been corrected by the umbilical cord stem cells transplantation. (5) At 75 days, the biopsy of calf muscle showed there were myoblast cells and muscular tubes growing. The dystrophin expressions were weak, but a few of them were strong. DNA analysis showed that the donor's gene DNA accounted for 1%-13%. At 126 days, obviously increased dystrophin positive muscular fibers of the boy were found. The donor's fibers rose to 2.5%-25%. (6) The serum CK of the boy declined from 5735 U/L to 274 U/L. (7) At 100 days, physical examination revealed improvement in his arms and legs. CONCLUSION: The therapy of Duchenne muscular dystrophy with allogeneic umbilical cord blood hematopoietic stem cell transplantation may reset up the blood-making function, decrease the serum CK level, restore the dystrophin in muscles, and improve the locomotive function of the DMD boy. These data suggest that the allogeneic umbilical cord blood hematopoietic stem cell transplantation may benefit the DMD boys.

Alprostadil↗

PubMed2005

[The proliferation, phenotype change and anti-tumor activity of cytokine induced killer cells].

AIM: To study the growth regularity, the phenotype change and the cytotoxicity of CIK cells. METHODS: The number of CIK cells was counted by living cell counting in different culturing time to observe the growth of the CIK cells, and the phenotype change of the CIK cells was detected by flow cytometry. Meanwhile cytotoxicity of CIK cells to tumor cell lines was also detected by CytoTox96 non-radiated cytotoxicity kit. RESULTS: After stimulated by cytokines and anti-CD3 antibody, CIK cells can proliferate significantly. The cell number of CIK was increased to 473.28+/-27.53 fold in serum-free medium plus auto-serum, 218.24+/-16.86 fold in serum-free medium and only 11.52+/-1.04 fold in RPMI1640 plus fetal FCS, respectively. The CD3(+)+CD8(+), CD3(+)+CD56(+), CD226(+)+CD11a(+) and CD305(+)+CD11a(+) cells were increased with the progression of the cultural time and the CD3(+)+CD4(+) cells were decreased with the progression of cultural time. The cytotoxicity of CIK cells to tumor cell lines was significantly higher than that of LAK cells (P<0.01) and its cytotoxicity was increased with progression of the cultural time. CONCLUSION: CIK cells have strong proliferative ability and higher cytotoxicity to tumor cells in vitro, which could be used as a potential anti-tumor adoptive immunotherapy in clinic.

Antigens, Differentiation, T-Lymphocyte↗

PubMed2005

[Effect of high pull J hook headgear on root resorption during orthodontic treatment].

PURPOSE: The purpose of this study was to evaluate the effect of high pull J hook headgear(HPHG) on root resorption of maxillary incisors during orthodontic treatment. METHODS: Sixty female adolescent subjects who had finished orthodontic treatment were selected. They were either Class I or Class II division I cases treated with standard edgewise appliances. Half of the patients(30 cases) had an additional HPHG to assist upper anterior teeth retraction. They were matched to the other 30 cases with age and type of malocclusion. Panoramic radiographs taken before and after the orthodontic treatment were used to evaluate the degree of root resorption on upper incisors. Chi(2) test was used for statistical analysis. RESULTS: The incidence of root resorption on upper incisors was significantly increased after orthodontic treatment in both HPHG and non-HPHG groups (P<0.01). Compared to the non-HPHG group, more teeth in HPHG group showed moderate or severe root resorption (P<0.01). Some cases even encountered extremely severe root resorption. CONCLUSION: A combination of HPHG might lead to more severe root resorption on maxillary incisors during orthodontic treatment.

Adolescent↗

PubMed2005

[Study on patient satisfaction with two type of Twin-block].

OBJECTIVE: To compare patient satisfaction with two type of Twin-block by clinic complain questionnaire, treatment effect satisfaction questionnaire and total satisfaction questionnaire, and to analyse their related factors with patient satisfaction. METHODS: 56 patients were randomly classified into fixed-Twin-block (TB1) and unfixed-Twin-block (TB2). The complaint and satisfaction of patients was evaluated by clinic complain questionnaire, treatment effect satisfaction questionnaire and total satisfaction questionnaire after 10 days and 6 months of treatment. RESULTS: (1) There was significant difference between the complaint of two groups in the sixth month, but there was no difference in the tenth day. (2) There was significant difference between the total satisfactory degree of two groups. (3) There was significant difference between the tooth-jaw effective index and the mandible effective index of the two groups. CONCLUSION: The satisfactory degree of fixed-Twin-block is superior to that of unfixed-Twin-block. The adorn fashion, treatment stage and functional position has influence on patient satisfaction.

Female↗

PubMed2005

[Construction, structure prediction and phylogenetic analysis of murine scFv gene against human cervical cancer].

AIM: To construct the gene of murine single-chain Fv fragment (scFv) against human cervical cancer and to predict the physical and chemical characteristics, secondary structure, tertiary structure and the molecular evolution of the scFv using computer-assisted modeling. METHODS: The variable region gene of the heavy and light chains were amplified respectively using recombinant DNA techniques from CSA125 hybridoma cells that can secret monoclonal antibodies with high activity and specificity against human cervical cancer. These two fragments were then spliced together through a flexible linker to scFv against human cervical cancer by using splicing overlap extension (SOE) PCR. The scFv gene, named CSAs-1, was cloned into the vector pMD18-T. The physical and chemical characteristics secondary and tertiary structure and the phylogenetic tree were predicted using Internet and corresponding softwares. RESULTS: The whole scFv gene was cloned successfully and encoded 278 amino acids. Theoretically, the CSAs-1 scFv was relative molecular masses 28,800, the isoelectric point (pI) was 7.215. PHDsec indicated that CSAs-1 was alpha+beta globin. There were many protein kinase C phosphorylation sites and casein kinase II phosphorylation sites in the V(H) and V(L) domains. The computer graphic modeling indicated the linker was isolated from V(H) and V(L). The V(L), as well as the V(H), was involved in composing the hydrophobic "pocket" which was beneficial to the antigen binding. Phylogenetic tree analysis indicated that V(H) genes from various vertebrate species formed three clusters that corresponded to three V(H) groups and that V(L) sequences from each species had a level of diversity similar to that of their V(H) genes. CSAs-1 V regions belong to A group. CONCLUSION: The construction and analysis of a molecular model of scFv laid the foundation for the further research into genetic engineering antibody and the mechanism of antigen-antibody interaction.

Animals↗

PubMed2005

[Expression of ATR-Fc fusion protein in CHO cells].

ATR-Fc is a fusion protein consisting of extracellular domain of human anthrax toxin receptor (ATR) and a fragment (hinge, CH2, and CH3 domains) of the Fc of human IgG1. The aim of ATR-Fc expression is to get an antibody-like molecule binding to protective antigen (PA), a component of anthrax toxins, this fusion protein may compete with cell surface receptor for PA binding, and block the transport of lethal factor (LF) and edema factor (EF) into cells, thereby act as an antitoxin to prevent and treat anthrax infection. A DNA fragment encoding N-terminal amino acids 1-227 of ATR and human IgG1 Fc was inserted into the Hind III and Not I sites of pcDNA3.1 to generate the eukaryotic vector pcDNA3.1/ATR-Fc for expression of ATR-Fc fusion protein. Using lipofectine-mediated gene transfer technique, pcDNA3.1/ATR-Fc was transfected into CHO-K1 cells. After selected with G418, a recombinant CHO cell line, ATR-Fc-1D5, whose expression level was about 10 - 15 microg/(10(6) cells x d), was established. The recombinant protein expressed by the ATR-Fc-1D5 cells was purified with protein A chromatography. The experimental results demonstrated a direct and specific interaction between ATR-Fc and PA assessed by ELISA.

Animals↗

PubMed2005

Ontogeny of expression of basic fibroblast growth factor and its receptors in human fetal skin.

OBJECTIVE: To investigate the expression characteristics of basic fibroblast growth factor (bFGF) and its receptors, flg (FGFR1) and bek (FGFR2), in fetal skin at different gestational ages underlying the relevance of these 3 proteins to skin development and the mechanisms underlying the phenotypic transition from scarless to scar-forming healing. METHODS: Eighteen specimens of fetal skin biopsies of human embryo were obtained from spontaneous abortions at different gestational ages of 13-32 weeks. Gene expression of bFGF, bek and flg was examined with reverse transcription-polymerase chain reaction (RT-PCR). The dynamic expression and distribution of these 3 proteins were detected with streptavidin peroxidase (SP) immunohistochemical staining method. RESULTS: In the early gestational fetal skin, genes of bFGF and flg were strongly expressed and more protein contents of these 2 proteins were found as compared with the genes at late gestation fetal skin (2.446+/-0.116 and 2.066+/-0.152 versus 2.157+/-0.101 and 1.818+/-0.086, respectively, P<0.05). On the contrary, the levels of gene expression and protein content of bek were not differently expressed in the early gestational fetal skin versus the late ones. Protein particles of bFGF were mainly distributed in the epidermal cells and some fibroblasts. Bek was mainly located in the cell membrane and cytoplasm of epidermal cells while flg protein was principally located in the epidermal cells, endothelial cells and some fibroblasts. CONCLUSIONS: The endogenous bFGF and their receptors might be involved in the cutaneous development at fetal stage. The differently expressing levels of bFGF and flg during gestation may be related to scarless or scar-forming repair during gestation.

Journal Article↗

PubMed2005

[Microkeratome-assisted lamellar keratoplasty for recurrent corneal granular dystrophy after phototherapeutic keratectomy].

OBJECTIVE: To evaluate the safety and efficacy of microkeratome-assisted lamellar keratoplasty (MLK) for the treatment of recurrent granular corneal dystrophy (GCD) after phototherapeutic keratectomy (PTK). METHODS: We performed a prospective study of nine eyes (seven patients) with recurrent granular dystrophy after PTK. A microkeratome was used to cut partial-thickness sections through the anterior surface of the donor and host corneas. The donor disc was placed on the recipient bed with four or eight interrupted sutures. The stitches were removed between 4 and 6 weeks after surgery. Visual acuity (VA), corneal clarity, corneal thickness, and corneal topography were assessed before and at different time points after surgery. RESULTS: During a mean follow-up period of (18.9 +/- 4.1) months, all grafts were transparent without visible opacity at the interface, and no serious complications occurred. The VA was improved in all cases. seven eyes had best corrected visual acuity with spectacles of 20/40 or better, two eyes reached 20/25. At the last follow-up visit more than 12 months postoperatively, the mean corneal refractive power increased significantly by (2.34 +/- 0.93) D (P < 0.01), and the corneal astigmatism significantly decreased by (0.91 +/- 0.98) D (P < 0.05). The mean corneal thickness was (477.4 +/- 26.9) microm preoperatively and (507.8 +/- 23.4) microm at the last follow-up visit (P < 0.01). CONCLUSIONS: Our findings suggest that MLK for the treatment of recurrent GCD is a safe and easy-to-perform method for restoring VA.

Adult↗

PubMed2005

[Gene expression of epidermal growth factor and epidermal growth factor receptor in oral lichen planus].

OBJECTIVE: To explore the expression of epidermal growth factor (EGF), epidermal growth factor receptor (EGFR), c-fos and c-jun in oral lichen planus (OLP). METHODS: The levels of gene expression of EGF, EGFR, c-fos and c-jun were detected with reverse transcription-polymerase chain reaction (RT-PCR) in 10 cases of erosive OLP, 12 cases of reticular OLP and 9 cases of normal oral mucosa. Protein contents and distribution of EGF, EGFR, C-fos and C-jun were examined with immunohistochemical technique in different tissues. RESULTS: The endogenous levels of EGFR mRNA and protein in erosive OLP were (55.9 +/- 23.1)% and (71.1 +/- 10.1)%, respectively, and significantly higher than those in reticular OLP and normal oral mucosa. The mRNA contents of c-fos and c-jun were significantly higher in erosive OLP than in normal oral mucosa. The positive cell rates of c-fos and c-jun protein in erosive OLP were 1.3 and 1.5 times of those in normal oral mucosa, respectively (P < 0.05). CONCLUSIONS: The probability of carcinomatous change of erosive OLP might be higher than that of reticular OLP, in which EGF and EGFR might play an important role.

Adult↗

PubMed2005

[Microclimate characters of urban forest in Shenyang].

This paper analyzed the diurnal changes of the temperature and humidity in Shenyang urban forest during its different growth stages. The results showed that air temperature was the lowest in the morning and the highest at noon. The highest peak point of air temperature lagged behind that of solar radiation about 2 hours, due to the influence of forest environment. The annual air temperature amplitude was in order of stop-growth period (dormancy stage) (DS) > prophase of growth season (PGS) > anaphase of growth season (AGS) > medium-term of growth season (MGS). Soil temperature of PGS, MGS and AGS at daytime was higher than that at night, while that of DS was in reverse. The daily soil temperature amplitude at different growth stages was in order of upper soil layer (20 cm) >medium soil layer (40 cm) >lower soil layer(80 cm),while the diurnal soil temperature amplitude in the same soil layer was in order of PGS > AGS > DS > MGS (20 cm) and PGS > DS > AGS > MGS (80 cm). The diurnal change of relative humidity was reverse to that of air- and soil temperature, which was higher at night than at daytime, and was in order of MGS > AGS > DS > PGS.

China↗

PubMed2005

[Study on changes in inflammatory cytokines and the relationship to multiple organ injury in rats with aspiration lung injury after fire-arm injury].

OBJECTIVE: To observe the phasic variations in concentrations of pro-inflammatory and anti-inflammatory cytokines, and to explore their potential roles in the occurrence and development process of multiple organ dysfunction. METHODS: Fire-arm induced aspiration lung injury model was replicated. The following parameters were observed: wet/dry weight ratio of rat's lungs, contents of albumin and lactate dehydrogenase (LDH), concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and IL-4 in bronchial alveolar lavage fluid (BALF), contents of alanine amino transferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), serum creatinine (SCr), and MB isoenzyme of creatine kinase (CK-MB). RESULTS: The wet/dry weight ratio of rat's lungs and contents of albumin and LDH in BALF increased with the passage of time. The concentration of TNF-alpha increased immediately after injury and reached the peak value at 2 hours. The concentration of IL-6 increased obviously 4 hours after injury, and maintained a high level from 4 hours to 24 hours. The concentration of IL-4 decreased from 6 hours to 8 hours after injury. The contents of ALT, AST, BUN, SCr and CK-MB increased continually after injury. CONCLUSION: Cytokines are the direct mediators for multiple organ failure (MOF), and MOF is triggered by TNF-alpha and a cascade of cytokine release, with a prolonged high-expression of IL-6. The loss of control of IL-4 aggravates the development of MOF.

Animals↗

PubMed2005

[Toxin-neutralizing monoclonal antibodies to the different domains of anthrax protective antigen].

Anthrax toxin from Bacillus anthracis is a three-component toxin consisting of lethal factor (LF), edema factor (EF), and protective antigen (PA). PA binds to target cells and transports LF or EF into the cell cytosol where they carry out their enzymatic functions. PA can induce protective immunity to the infection of the bacterium and is the major component in the only anthrax vaccine approved by FDA of USA. Mouse hybridoma clones specifically secreting anti-PA monoclonal antibodies (MAbs) were generated by cell fusion technique and their ability to neutralize anthrax lethal toxin activities was screened in vitro on a toxin-sensitive cell line. Nine toxin-neutralizing MAbs obtained were then characterized for the domains of PA they recognize, and the epitope regions they bind were analyzed by competitive binding ELISA. It was found that these MAbs bind four potential neutralizing epitope regions in three different domains of PA. Four MAbs bind to two non-overlapping epitope regions in domain 4 of PA and may prevent the binding of PA to its cell receptor. Four MAbs bind to domain 2, a domain involved in membrane insertion. One MAb binds to domain 3, a region involved in the oligomerization of PA. The results provided supporting evidence that PA has several neutralizing epitopes, and offered potential immunotherapeutic agents for the treatment of anthrax.

Animals↗

PubMed2005

[Chemical components and antimicrobial activity of essential oils in Cunninghamia lanceolata heartwood].

In this study, the essential oils in Cunninghamia lanceolata heartwood were water-steam distilled, and their chemical components were analyzed by column chromatography and GC-MS, with their antimicrobial activity tested. The results showed that the essential oils content was 1.794-2.076 (w/w), and 47 peaks were separated. 27 compounds, accounted for 99% of crude essential oils, were identified. The essential oils had an obvious antimicrobial activity against Escherichia coli, Staphylococcus aureus, Bacillus sabtills and Salmonella typhi, and cedrol, occupying 76.27% of essential oils, was the major component with antimicrobial activity.

Anti-Bacterial Agents↗

PubMed2004

Activity-dependent internalization of smoothened mediated by beta-arrestin 2 and GRK2.

Binding of Sonic Hedgehog (Shh) to Patched (Ptc) relieves the latter's tonic inhibition of Smoothened (Smo), a receptor that spans the cell membrane seven times. This initiates signaling which, by unknown mechanisms, regulates vertebrate developmental processes. We find that two molecules interact with mammalian Smo in an activation-dependent manner: G protein-coupled receptor kinase 2 (GRK2) leads to phosphorylation of Smo, and beta-arrestin 2 fused to green fluorescent protein interacts with Smo. These two processes promote endocytosis of Smo in clathrin-coated pits. Ptc inhibits association of beta-arrestin 2 with Smo, and this inhibition is relieved in cells treated with Shh. A Smo agonist stimulated and a Smo antagonist (cyclopamine) inhibited both phosphorylation of Smo by GRK2 and interaction of beta-arrestin 2 with Smo. beta-Arrestin 2 and GRK2 are thus potential mediators of signaling by activated Smo.

Arrestins↗