Biomedical subjects

Feng Chen

Publications and source records attributed to Feng Chen.

At least 217 records · Page 12Linked to original sources

PubMed2003

[Management of sheath after repair of double tendons in zone II d].

OBJECTIVE: To evaluate the management of sheath after repair of double tendons in clean-cut injury or severe injury in zone II d. METHODS: Forty-eight white leghorn chickens were divided into 4 groups. Both FDS and FDP tendons in zone II d of long toes were repaired with modified Kessler suture after tendon transection in group A (clean-cut tendon injury, sheath closure), group B (clean-cut tendon injury, sheath excision), group C (severe tendon injury, sheath closure) and group D (severe tendon injury, sheath excision), respectively. Biomechanical studies of gliding excursion and work of flexion were carried out 6 weeks and 12 weeks after tendon repair. The extent of adhesion was examined. RESULTS: After 6 and 12 weeks of repair, there were no significant differences in tendon excursion and work of flexion of the toes between groups A and B. Excursions of FDP tendons in group D was significantly larger than that in group C (P < 0.05). Work of flexion and extent of adhesion in group D was significantly less than that in group C (P < 0.05). CONCLUSION: The above results indicate that sheath can be closed after repair of both FDS and FDP tendons in clean-cut injury and that sheath should be excised in severe injury in zone II d.

Animals↗

PubMed2003

[Effect of the different diameter of posterior capsulotomy on visual field].

OBJECTIVE: The purpose of this study is to determine the influence of two different diameter of posterior capsulotomy on visual field. METHODS: Forty patients with posterior capsule opacification (PCO) of grade II after phacoemulsification and intraocular lens implantation were randomly divided into two groups. 20 cases received laser capsulotomy with 2 mm diameter. Other 20 cases received laser capsulotomy with 4 mm diameter. One and half months after laser capsulotomy, vision field of every patient was examined using the automated perimetry for central 30 degrees and peripheral 60 degrees. Visual field in 21 patients with a transparent posterior capsule after cataract surgery was also evaluated by the same automated perimetry. RESULTS: There were significant reductions in the total visual field sensitivity, the mean deviation (MD) and the pattern standard deviation (PSD) in 2 mm diameter capsulotomy group compared with 4 mm diameter capsulotomy group (P < 0.001). There were no significant difference in visual field between 4 mm capsulotomy group and the transparent posterior capsule group (P > 0.05). CONCLUSIONS: Better visual acuity could be obtained after laser capsulotomy with 2 mm capsulotomy, however the generalized sensitivity reduction and irregular localized depression of visual island might occurred. 4 mm diameter capsulotomy may be a better choice in laser capsulotomy in patients with PCO.

Aged↗

PubMed2003

[Sequence analysis and expression study of BRI gene in two lung adenocarcinoma cell lines with different metastatic potential].

OBJECTIVE: To investigate the sequence of amyloid fibrils (BRI) gene and its expression in two lung adenocarcinoma cell lines AGZY83-a and Anip973 with the same tumor origin but different metastatic potential. METHODS: DNA sequencing, sequential G banding fluorescence in situ hybridization (FISH) and Northern blot were used to analyze the sequence and expression of BRI gene was in two lung adenocarcinoma cell lines with different metastatic potential. RESULTS: The expression of BRI gene was up-regulated in the highly metastatic cell line Anip973 and was down-regulated in the low metastatic cell line AGZY83-a from which the Anip973 was derived. FISH results disclosed that in the two cell lines, the same rearrangements existed in the chromosome region where BRI gene was located, but in Anip973, amplification took place in the chromosome region where BRI gene was located. DNA sequencing results showed different mutations in the 5' untranslated region of BRI gene in the two cell lines. CONCLUSION: The above results revealed that there was no relation between BRI gene differential expression and rearrangements of chromosome. The amplification of the chromosome region where BRI gene was located and the different mutations in the 5' untranslated region of BRI gene probably contributed to the differential expression.

Adaptor Proteins, Signal Transducing↗

PubMed2003

Apolipoprotein E genotype in patients with Alzheimer's disease.

OBJECTIVE: To explore the frequency and significance of ApoE gene polymorphisms in patients with sporadic Alzheimer's disease (AD). METHODS: Single nucleotide polymorphisms of the ApoE gene were analyzed in 32 cases of AD and 26 controls, using PCR and gene sequencing. RESULTS: The single nucleotide polymorphism of ApoE gene 462C/G was significantly associated with AD (P < 0.05). CONCLUSIONS: The 462C/G polymorphism might be a specific genotype in Chinese patients with sporadic AD.

Aged↗

PubMed2003

[Population-based study of human papillomavirus infection in high-risk area for cervical cancer in Shanxi Province, China].

OBJECTIVES: To investigate the prevalence of oncogenic type of human papillomavirus (HPV) infection and identify the high risk population for conducting immuno/chemoprevention of cervical cancer. METHODS: All married women aged 30 to 50 with no history of hysterectomy, pelvic radiation and non-pregnant from certain villages of Xiangyuan and Yangcheng County were invited. This study was conducted through two phases. In phase one, subjects sampled the vaginal secretions using the collectors after signing the informed consent. And physicians sampled exfoliated cells from cervix in the phase two. All the specimens were tested with the Hybrid Capture 2 test. The data was managed and analyzed by VFP and SPSS software. RESULTS: There were 9,683 women participated in this study. Local women welcomed this study and population compliance rate was 75.4%. In tested population, we found 2,666 subjects of HPV DNA positive and HPV prevalence was 27.5%. The rates of different age group were 24.5% (30-34 yrs), 27.4% (35-39 yrs), 28.2% (40-44 yrs), 27.4% (45-50 yrs) respectively and had no significant differences (P = 0.604). The rates were slightly increased with the higher education level and had no differences (P = 0.106). The rate in mountain areas was higher than that in half-mountain areas (P = 0.001). CONCLUSIONS: The prevalence of HPV infection is indeed high in this region. Local women and health professionals welcome the activities of cervical cancer screening and prevention. It is an emergent task to improve their sanitary condition and prevent them from cervical cancer in these women. A women health cohort is established successfully among high HPV exposed women in rural China. The extensive biologic specimen repository has been successfully established to simultaneously study the etiology, early detection, and immuno/chemoprevention of cervical cancer.

Adult↗

PubMed2003

[Detection and analysis of the new kind of G743C and G743A point mutation of HBV P gene in hepatitis B virus infected patients resistant to lamivudine].

OBJECTIVE: To explore the point mutation in hepatitis B virus polymerase (HBV P) gene in HBV-infected patients resistant to lamivudine. METHODS: HBV P gene was amplified by PCR and the products was sequenced to analyze the YMDD mutation. Then the variants were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with the following restriction enzymes: Fok I, Ssp I, Alw441 and were separated by 8.0% polyacrylamide gel electrophoresis. RESULTS: Comparing with the sequences of standard HBV genome, there were 16 patients with G743C mutation and 1 patient with G743A mutation, and the codon ATG turned to ATC and ATA, YMDD motif changed into YIDD. But this kind of YIDD mutation was not proved by PCR-RFLP assay in the 17 patients. CONCLUSIONS: The G743C and G743A mutations in HBV P gene, resulting in YMDD motif changed into YIDD, are detected only by direct sequencing, not by PCR-RFLP. The new kind of G743C and G743A point mutations in HBV P gene is important for the detection of HBV P gene YMDD mutation.

Adult↗

PubMed2003

[Mapping quantitative trait loci associated with rice grain shape based on an indica/japonica backcross population].

Appearance of rice grain represents a major character of rice quality in many rice-producing areas of the world, especially in hybrid rice production in China. In this study, we conducted a molecular marker-based genetic analysis of the traits that are determinants of the appearance quality of rice grains, including grain length, grain width and grain shape (measured as grain length to grain width ratio). Two typical indica/japonica varieties Balilla and Nantehao(NTH) were selected to construct Balilla/NTH//Balilla backcross population containing 142 individuals. In the population, grain length, grain width and grain shape all conform to the normal distribution with certain transgressive segregation. It can be deduced that all of three traits were controlled by some quantitative trait loci (QTLs). In order to explore the QTLs effect, number and location, a linkage map consisting of 108 SSR markers based on the backcross population was constructed, and QTLs mapping was carried out for grain length, grain width and grain shape. A QTL, qGL-12, was detected for grain length at the interval RM101-RM270 on chromosome 12, its additive effect was 0.26 mm, and can explain 16.7% genetic variation. As for grain width trait, two QTLs were found, qGW-2 located at RM154-RM211 interval on chromosome 2, and qGW-3 at interval RM257-RM175 on chromosome 3, accounting for 11.5% and 16.6% genetic variation, respectively. The alleles at qGW-2 and qGW-3 from parent Balilla can increase grain width by 0.10 mm and 0.12 mm. For grain shape, 3 QTLs, qLW-2, qLW-6 and qLW-7 were found, located on chromosome 2, 6, and 7, respectively. qLW-2 and qLW-7 had positive effect, and they can explain 12.7% and 18.3% genetic variation, while qLW-6 had negative effect and contributed 11.5% genetic variation to the backcross population. The prospects of application of linkage relationship between SSR marker and QTLs in marker based selection (MAS) in rice breeding, and the improvement of grain shape and rice appearance quality were discussed.

Chromosome Mapping↗

PubMed2003

[Polymorphism analysis for DYS19 and DYS287 of three Li populations in Haina Island, China].

The distribution of Y-chromosome specific microsatellite DYS19, in 289 males of three ethnic populations in Hainan Island was studied with the method of PCR followed by denatured polyacrylamide gel electrophoresis and silver staining. The three ethnic populations are Bendi Li, Qi Li and Ha Li. The results showed that four alleles (190bp, 194bp, 198bp, 202bp designated as alleles B, C, D and E respectively), were observed in DYS19, the frequency ranged from 0.660-0.854, and was predominant in three Li subgroups. The pairwise comparison with Fisher's Exact test reveals that there exists significant difference (P<0.01) in DYS19 phenotype distribution between Qi Li and Ha Li populations. The polymorphism of the Y-chromosome specific Alu insert sequence DYS287 was investigated also in three Li populations. The results demonstrated that with 150 bp product in all Bendi-Li, Qi-li and Ha-li, YAP element is absent. The preliminary study provides reference populations for detecting male migration events and for reconstructing paternal history.

English Abstract↗

PubMed2002

Antitumor vaccination with HER-2-derived recombinant antigens.

Certain types of malignant tumors overexpress HER-2, a transmembrane glycoprotein of the class I receptor tyrosine kinase erbB family. To develop an effective HER-2 vaccine for the selective immunotherapy of these malignancies, we have genetically engineered fusion proteins containing portions of extra- and intracellular HER-2 domains. Activated dendritic cells (DC) cocultured with these novel antigens (Ag) could induce potent responses of Ag-specific T-cell lines in vitro and a protection against HER-2-expressing tumor in vivo. The protective capabilities of HER-2-derived fusion proteins correlated with the efficiency of their presentation to Ag-specific T-cell hybridomas. The most effective Ag contained GM-CSF, the presence of which facilitated their internalization by antigen-presenting cells (APC) in a receptor-mediated manner.

Amino Acid Sequence↗

PubMed2002

Preparative separation and determination of matrine from the Chinese medicinal plant Sophora flavescens Ait by molecularly imprinted solid-phase extraction.

Molecularly imprinted microspheres (MIMs) were synthesized by micro-suspension polymerization using matrine (MT) as template. The MIMs were employed for solid-phase extraction (SPE) and as chromatographic stationary phase for the determination of MT from the Chinese medicinal plant Sophora flavescens. The effects of the various eluents, their concentrations and volumes on the retention behavior were investigated. The selectivity and capacity of the imprinted microspheres against MT was also discussed. The results showed that the MIMs exhibited stronger specific affinity to MT than to oxymatrine (OMT). Methanol-water (3:7, v/v) was used for washing impurities from the MIMs-SPE cartridge loaded with the herb extracts, while methanol-glacial acetic acid (9:1, v/v) was used for eluting MT. The maximum load of MT and the recovery of MIMs cartridge towards MT were 38.7 microg g(-1) and 71.4%, respectively. The method developed might be used to separate and extract effective constituents from Chinese medicinal plants on a large scale.

Alkaloids↗

PubMed2002

Caspase proteolysis of desmin produces a dominant-negative inhibitor of intermediate filaments and promotes apoptosis.

Caspase cleavage of key cytoskeletal proteins, including several intermediate filament proteins, triggers the dramatic disassembly of the cytoskeleton that characterizes apoptosis. Here we describe the muscle-specific intermediate filament protein desmin as a novel caspase substrate. Desmin is cleaved selectively at a conserved Asp residue in its L1-L2 linker domain (VEMD downward arrow M(264)) by caspase-6 in vitro and in myogenic cells undergoing apoptosis. We demonstrate that caspase cleavage of desmin at Asp(263) has important functional consequences, including the production of an amino-terminal cleavage product, N-desmin, which is unable to assemble into intermediate filaments, instead forming large intracellular aggregates. Moreover, N-desmin functions as a dominant-negative inhibitor of filament assembly, both for desmin and the structurally related intermediate filament protein vimentin. We also show that stable expression of a caspase cleavage-resistant desmin D263E mutant partially protects cells from tumor necrosis factor-alpha-induced apoptosis. Taken together, these results indicate that caspase proteolysis of desmin at Asp(263) produces a dominant-negative inhibitor of intermediate filaments and actively participates in the execution of apoptosis. In addition, these findings provide further evidence that the intermediate filament cytoskeleton has been targeted systematically for degradation during apoptosis.

Animals↗

PubMed2002

The small heat shock protein alpha B-crystallin negatively regulates apoptosis during myogenic differentiation by inhibiting caspase-3 activation.

Myoblasts respond to growth factor deprivation either by differentiating into multinucleated myotubes or by undergoing apoptosis; hence, the acquisition of apoptosis resistance by myogenic precursors is essential for their development. Here we demonstrate that the expression of the small heat shock protein alpha B-crystallin is selectively induced in C2C12 myoblasts that are resistant to differentiation-induced apoptosis, and we show that this induction occurs at an early stage in their differentiation in vitro. In contrast, the expression of several known anti-apoptotic proteins (FLIP, XIAP, Bcl-x(L)) was not altered during myogenesis. We also demonstrate that ectopic expression of alpha B-crystallin, but not the closely related small heat shock protein Hsp27, renders C2C12 myoblasts resistant to differentiation-induced apoptosis. Furthermore, we show that the myopathy-causing R120G alpha B-crystallin mutant is partly impaired in its cytoprotective function, whereas a pseudophosphorylation alpha B-crystallin mutant that mimics stress-induced phosphorylation is completely devoid of anti-apoptotic activity. Finally, we demonstrate that alpha B-crystallin negatively regulates apoptosis during myogenesis by inhibiting the proteolytic activation of caspase-3, whereas the R120G and pseudophosphorylation mutants are defective in this function. Taken together, our findings indicate that alpha B-crystallin is a novel negative regulator of myogenic apoptosis that directly links the differentiation program to apoptosis resistance.

Animals↗

PubMed2002

Tetraaqua(1,10-phenanthroline-kappa(2)N,N')manganese(II) sulfate dihydrate.

The title compound, [Mn(C(12)H(8)N(2))(H(2)O)(4)]SO(4).2H(2)O, was obtained unexpectedly as a by-product from the reaction of sodium maleate, 1,10-phenanthroline (phen) and manganese sulfate tetrahydrate. The Mn atom is coordinated by the two N atoms of the phen ligand and four water O atoms in a highly distorted octahedral geometry, with Mn[bond]O distances in the range 2.155 (2)-2.203 (2) A and Mn[bond]N distances of 2.254 (2) and 2.272 (3) A. Extensive hydrogen-bonding interactions involving the water molecules and sulfate anions, and stacking interactions involving the phen rings, are observed in the crystal structure.

Journal Article↗

PubMed2002

Caspase proteolysis of the cohesin component RAD21 promotes apoptosis.

Caspases are a conserved family of proteases that play a critical role in the execution of apoptosis by cleaving key cellular proteins at Asp residues and modifying their function. Using an expression cloning strategy we recently developed, we isolated human RAD21/SCC1/MCD1 as a novel caspase substrate. RAD21 is a component of the cohesin complex that holds sister chromatids together during mitosis and repairs double-strand DNA breaks. Interestingly, RAD21 is cleaved by a caspase-like Esp1/separase at the onset of anaphase to trigger sister chromatid separation. Here, we demonstrate that human RAD21 is preferentially cleaved at Asp(279) by caspases-3 and -7 in vitro to generate two major proteolytic products of approximately 65 and 48 kDa. Moreover, we show that RAD21 is specifically proteolyzed by caspases into a similarly sized 65-kDa carboxyl-terminal product in cells undergoing apoptosis in response to diverse stimuli. We also demonstrate that caspase proteolysis of RAD21 precedes apoptotic chromatin condensation and has important functional consequences, viz. the partial removal of RAD21 from chromatin and the production of a proapoptotic carboxyl-terminal cleavage product that amplifies the cell death signal. Taken together, these findings point to an entirely novel function of RAD21 in the execution of apoptosis.

Apoptosis↗

PubMed2002

Isolation and purification of lutein from the microalga Chlorella vulgaris by extraction after saponification.

A simple and efficient method for the isolation and purification of lutein from the microalga Chlorella vulgaris was developed. Crude lutein was obtained by extraction with dichloromethane from the microalga after saponification. Partition values of lutein in the two-phase system of ethanol-water-dichloromethane at different ratios were measured by HPLC so as to assist the determination of an appropriate condition for washing water-soluble impurities in the crude lutein. Partition values of lutein in another two-phase system of ethanol-water-hexane at different ratios were also measured by HPLC for determining the condition for removing fat-soluble impurities. The water-soluble impurities in the crude lutein were removed by washing with 30% aqueous ethanol, and the fat-soluble impurities were removed by extraction with hexane. The final purity of lutein obtained was 90-98%, and the yield was 85-91%.

Chlorella↗

PubMed2002

Cdc42 facilitates invasion but not the actin-based motility of Shigella.

The enteric pathogen Shigella utilizes host-encoded proteins to invade the gastrointestinal tract. Efficient invasion of host cells requires the stimulation of Rho-family GTPases and cytoskeletal alterations by Shigella-encoded IpaC. Following invasion and lysis of the phagosome, Shigella exploits the host's actin-based polymerization machinery to assemble an actin tail that serves as the propulsive force required for spreading within and between cells. The Shigella surface protein IcsA stimulates actin-tail formation by recruiting host-encoded N-WASP to drive Arp2/3-mediated actin assembly. N-WASP is absolutely required for Shigella motility, but not for Shigella invasion. Although Rho-family GTPases have been implicated in both the invasion and motility of Shigella, the role of Cdc42, an N-WASP activator, in this process has been controversial. In these studies, we have examined the role of Cdc42 in Shigella invasion and actin-based motility using Cdc42-deficient cells. We demonstrate that Cdc42 is required for efficient Shigella invasion but reveal a minor Cdc42-independent pathway that can permit Shigella invasion. However, the actin-based motility of Shigella, as well as vaccinia, proceeds unperturbed in the absence of Cdc42. These data further support the involvement of distinct host-encoded proteins in the steps regulating invasion and intercellular spread of Shigella.

Actins↗

PubMed2002

Preparative isolation and purification of salvianolic acid B from the Chinese medicinal plant Salvia miltiorrhiza by high-speed counter-current chromatography.

High-speed counter-current chromatography was applied to the isolation and purification of salvianolic acid B from the Chinese medicinal plant Salvia miltiorrhiza Bunge. The crude salvianolic acid B was obtained by extraction with ethanol-water from S. miltiorrhiza Bunge. Preparative high-speed counter-current chromatography with a two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-water (3:7:1:9, v/v) was successfully performed yielding 342 mg salvianolic acid B at 98% purity from 500 mg of the crude extract in a one-step separation.

Benzofurans↗

PubMed2002

A new haplogroup pattern displayed in Fujian Han in China.

Human Y-chromosomal binary polymorphisms have been considered to preserve the paternal genetic legacy and provide evidence on human evolution and the genetic relationships among and demographic history of different populations. To reveal the genetic origin and immigration of the Fujian Han, 13 binary markers on the Y chromosome were used to screen Fujian Han by allele-specific polymerase chain reaction. The results indicated that the M9G marker was highly prevalent (96.20%), suggesting a significant genetic drift. In addition, M122C frequency was only 22.78%, and M45A and M103T were default. The distinctive haplogroup frequencies (H1, H5, and H6/7/8) imply that the haplogroup pattern is a relatively ancestral and interim type.

Asian People↗