Biomedical subjects

J P Chen

Publications and source records attributed to J P Chen.

At least 19 recordsLinked to original sources

PubMed2006

Construction of an infectious cDNA clone of Ribgrass mosaic virus Shanghai isolate and its modification to express an epitope of Mycobacterium tuberculosis.

Infectious cDNA clones of the Shanghai isolate of Ribgrass mosaic virus (RMV) were produced by joining four overlapping cDNA fragments and also in a single step by long template PCR. After inoculation of Nicotiana glutinosa with either RNA transcripts or the cDNA under the control of the CaMV 35S promoter, plants developed typical symptoms, and viral coat protein could be detected in them by Western blot analysis. However, compared to plants inoculated with purified viral RNA, lesions were fewer and appeared more slowly. An epitope of the Mycobacterium tuberculosis 31-kDa protein was inserted at the C-terminus of the viral coat protein by PCR using two overlapping fragments. The modified clone was also infectious and the foreign epitope could be detected serologically in the electron microscope and by Western blot analysis. The results demonstrate the potential of RMV as a viral gene vector.

Antigens, Bacterial↗

PubMed2006

Antisense c-myc fragments induce normal differentiation cycles in HL-60 cells.

BACKGROUND: We have investigated the potential for using antisense technology as a means of delivering treatment for acute myeloblastic leukaemia (FAB-M2) by gene therapy. MATERIALS AND METHODS: A test recombinant adenovirus vector was constructed containing human c-myc antisense fragments to study the effects of altering c-myc overexpression in the human HL-60 cell line. Control vector contained the human LacZ gene. Transfection efficiency in HL-60 cells was determined using control vector in the presence of protamine sulphate and multiplicity of infection of 100. Morphological and mechanistic changes were assessed using immunohistochemical analysis, flow cytometry and reverse transcription-polymerase chain reaction. RESULTS: Transfection efficiency of control vector was 79.8% and morphological differences were observed after 72 h in culture. The rate of proliferation of HL-60 cells infected with test vector was inhibited by 73% compared with control following 6 days in culture. Normal terminal differentiation leading to apoptosis was only evident in test vector infected cells. Peak apoptosis (34.7%) was detected at day 6 and cell cycle arrest at days 2, 4 and 6. Expression of c-fos protein was significantly increased in test vector treated cells with a noticeable down-regulation of c-myc expression. CONCLUSIONS: These data suggest that transfection of a human HL-60 cell line with vector containing c-myc antisense fragments could inhibit proliferation, but induce differentiation and apoptosis. Thus, we believe that further study of this construct is warranted as a potential gene therapy reagent for treatment of acute myeloblastic leukaemia.

Adenoviridae↗

PubMed2006

[Establishment of Z-HL16C cell line.].

BACKGROUND: To establish and study the nature and the application of Z-HL16C cell line. METHODS: The cell line was continuously passed, frozen stored and recovered. Its application was expanded and the cell type was identified. RESULTS: The cell line had an epithelial-cell-like shape, the size appeared uniform, the cell boundary was distinct. It has been continuously passed, frozen stored and recovered for ten years. Its recovery rate was about 90%. It has been proved to be sensitive to the tested viruses which were enteroviruses (Polio, Cox, Echo), influenza viruses, parainfluenzaviruses, adenoviruses, measles virus. This cell line has been identified as a cancerization cell. CONCLUSION: The cell line Z-HL16C has been stably established, it has a broad spectrum in sensitivity for culturing viruses.

Cell Line↗

PubMed2005

In vitro estrogenic activities of Chinese medicinal plants traditionally used for the management of menopausal symptoms.

The estrogenic activity of 70% EtOH extracts of 32 traditional Chinese medicinal plants, selected according to their reported efficacy for the treatment of menopausal symptoms, was assessed using a recombinant yeast system with both a human estrogen receptor expression plasmid and a reporter plasmid. Among them, 11 (34%) species proved to be active. Polygonum cuspidatum had the highest estrogenic relative potency (RP) (3.28 x 10(-3)), followed by Rheumpalmatum (3.85 x 10(-4)), Cassia obtusifolia (3.49 x 10(-4)), Polygonum multiflorum (2.87 x 10(-4)), Epimedium brevicornum (2.30 x 10(-4)), Psoralea corylifolia (1.90 x 10(-4)), Cynomorium songaricum (1.78 x 10(-4)), Belamcanda chinensis (1.26 x 10(-4)), Scutellaria baicalensis (8.77 x 10(-5)), Astragalus membranaceus (8.47 x 10(-5)) and Pueraria lobata (6.17 x 10(-5)). The EC(50) value of 17beta-estradiol used as the positive control was 0.205+/-0.025 ng/ml (RP=100). This study gave support to the reported efficacy of Chinese medicines used for hormone replacement therapy.

Female↗

PubMed2004

Improved liquid chromatographic method for determination of carotenoids in Taiwanese mango (Mangifera indica L.).

An HPLC method was developed to determine the various carotenoids in Taiwanese mango (Mangifera indica L.). Initially, the peel and seed of mangoes were removed, the pulps were cut into pieces, freeze-dried, ground into powder, extracted and subjected to HPLC analysis. A mobile phase of methanol-isopropanol (99:1, v/v) (A) and methylene chloride (100%) (B) with the following gradient elution was developed: 100% A and 0% B in the beginning, maintained for 15 min, decreased to 70% A in 45 min, maintained for 15 min and returned to 100% A in 65 min. A total of 25 carotenoids were resolved within 53 min by using a C-30 column with flow rate at 1 mL/min and detection at 450 nm. alpha-Carotene was used as an internal standard to quantify all the carotenoids. All-trans-beta-carotene was present in largest amount (29.34 microg/g), followed by cis isomers of beta-carotene (9.86 microg/g), violaxanthin and its cis isomers (6.40 microg/g), neochrome (5.03 microg/g), luteoxanthin (3.6 microg/g), neoxanthin and its cis isomers (1.88 microg/g), zeaxanthin (1.16 microg/g) and 9- or 9'-cis-lutein (0.78 microg/g).

Carotenoids↗

PubMed2004

Measurement of the exclusive 3He(e,e'p) reaction below the quasielastic peak.

New, high-precision measurements of the 3He(e,e(')p) reaction using the A1 Collaboration spectrometers at the Mainz microtron MAMI are presented. These were performed in antiparallel kinematics at energy transfers below the quasielastic peak, and at a central momentum transfer of 685 MeV/c. Cross sections and distorted momentum distributions were extracted and compared to theoretical predictions and existing data. The longitudinal and transverse behavior of the cross section was also studied. Sizable differences in the cross-section behavior from theoretical predictions based on the plane wave impulse approximation were observed in both the two- and three-body breakup channels. Full Faddeev-type calculations account for some of the observed excess cross-section, but significant differences remain.

Journal Article↗

PubMed2003

Cross-section measurement of charged-pion photoproduction from hydrogen and deuterium.

We have measured the differential cross section for the gamman-->pi(-)p and gammap-->pi(+)n reactions at theta(c.m.)=90 degrees in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at E(gamma) greater, similar 3.3 GeV exhibit a global scaling behavior for both pi(-) and pi(+) photoproduction, consistent with the constituent counting rule and the existing pi(+) photoproduction data. Possible oscillations around the scaling value are suggested by these new data. The data show enhancement in the scaled cross section at a center-of-mass energy near 2.2 GeV. The cross section ratio of exclusive pi(-) to pi(+) photoproduction at high energy is consistent with the prediction based on one-hard-gluon-exchange diagrams.

Journal Article↗

PubMed2003

Behaviors and mechanisms of copper adsorption on hydrolyzed polyacrylonitrile fibers.

Polyacrylonitrile fiber (PANF) was hydrolyzed in a solution of sodium hydroxide and the hydrolyzed polyacrylonitrile fiber (HPANF) was used as an adsorbent to remove copper ions from aqueous solution. Scanning electron microscopy (SEM) showed that the hydrolysis process made the surface of HPANF rougher than that of PANF. Fourier transform infrared (FTIR) spectroscopy revealed that the HPANF contained conjugated imine (-Cz=Nz-) sequences. Batch adsorption results indicated that the HPANF was very effective in adsorbing copper, and the adsorption equilibrium could be reached within 10-20 min. Atomic force microscopy (AFM) showed that some aggregates formed on the surface of the HPANF after copper ion adsorption and the average surface roughness (R(a)) value of the HPANF changed from 0.363 to 3.763 nm due to copper adsorption. FTIR analysis indicated that copper adsorption caused a decrease of the light adsorption intensity of the imine (-Cz=Nz-) groups at 1573 and 1406 cm(-1) wavenumbers, and X-ray photoelectron spectroscopy (XPS) showed that the binding energy (BE) of some of the nitrogen atoms in the HPANF increased to a greater value due to copper adsorption. The FTIR and XPS results suggest that the adsorption of copper ions to the HPANF is attributed to the imine groups on the surface of the HPANF.

Journal Article↗

PubMed2002

Characterisation of a potyvirus and a potexvirus from Chinese scallion.

Molecular analyses of viruses infecting Chinese scallion (Allium chinense G. Don) showed that the plants did not contain any of the poty-, carla- or allexiviruses that are common in garlic plants in China. The complete sequences of a potyvirus and a potexvirus were determined and these were shown to represent different viruses from any in the databases. They could be transmitted mechanically to scallion but not to other Allium species (including garlic) or to Narcissus. The potyvirus, tentatively named Scallion mosaic virus, has a distant relationship (c. 62% nucleotide identity over the entire genome) to Turnip mosaic virus and Japanese yam mosaic virus, with which it grouped in phylogenetic analyses. Its genome is 9324 nts long, encoding a 341.3 kDa polyprotein of 3001 amino acids. The potexvirus, tentatively named Scallion virus X, has a genome 6987 nts long and its organisation was similar to that of the other potexviruses but with only 46.3-63.2% nucleotides identical to them. It is most closely related to Narcissus mosaic virus but phylogenetic analyses indicate that it should be considered a distinct species. Neither of the viruses have been detected in garlic, although the two host plants are closely related.

Allium↗

PubMed2001

Precision measurement of the spin-dependent asymmetry in the threshold region of 3He(e, e').

We present the first precision measurement of the spin-dependent asymmetry in the threshold region of 3He(e,e') at Q2 values of 0.1 and 0.2 (GeV/c)2. The agreement between the data and nonrelativistic Faddeev calculations which include both final-state interactions and meson-exchange current effects is very good at Q2 = 0.1 (GeV/c)2, while a small discrepancy at Q2 = 0.2 (GeV/c)2 is observed.

Journal Article↗

PubMed2001

Dynamics of the 16O(e, e'p) reaction at high missing energies.

We measured the cross section and response functions for the quasielastic 16O(e,e'p) reaction for missing energies 25< or =E(m)< or =120 MeV at missing momenta P(m)< or =340 MeV/c. For 25<E(m)<50 MeV and P(m) approximately 60 MeV/c, the reaction is dominated by a single 1s(1/2) proton knockout. At larger P(m), the single-particle aspects are increasingly masked by more complicated processes. Calculations which include pion exchange currents, isobar currents, and short-range correlations account for the shape and the transversity, but for only half of the magnitude of the measured cross section.

Journal Article↗

PubMed2001

Polarization measurements in high-energy deuteron photodisintegration.

We present measurements of the recoil proton polarization for the d(gamma-->,p-->)n reaction at straight theta(c.m.) = 90 degrees for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization p(y) vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(gamma,p)n cross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime.

Journal Article↗

PubMed2001

Molecular characterisation of segments 1 to 6 of Rice black-streaked dwarf virus from China provides the complete genome.

The nucleotide sequences of segments S1 to S6 of a Chinese isolate of Rice black-streaked dwarf virus (RBSDV) were determined. This provides the first complete sequence of a plant pathogenic member of the genus Fijivirus. The complete ten-segment genome has 29,141 nucleotides, making it the largest reovirus genome so far reported. Each of the segments S1-S6 is predicted to encode a single major protein. Protein comparisons indicated that S1 encoded an RNA dependent RNA polymerase, with similarities to that encoded by S1 of Nilaparvata lugens reovirus (NLRV). S2 and S3 appeared to be homologous to S3 and S4 respectively of both Fiji disease virus (FDV) and NLRV. The protein encoded on S4 showed some similarity to that of NLRV S2. The proteins encoded on S5 and S6, though similar in size to those of NLRV S5 and S6, had no detectable homologies to them or to any other known protein.

Amino Acid Sequence↗

PubMed2001

Novel cake characteristics of waste-activated sludge.

Breaking down the time limit constraints for conventional compression-permeation (C-P) cell test, this work has, for the first time, experimentally evaluated the cake characteristics of viable waste-activated sludge subject to polyelectrolyte flocculation and to freeze/thaw treatment under a pressure range of 25-200 kPa. There exists a threshold pressure exceeding which the cake structure would significantly deteriorate. Also, the present biological sludge is a "super-compactible" sludge, whose compactibility is greater than most data ever reported in open literature. The information presented herein has implications to filter design/operation and can be used as a reference data set for examining the existing filtration theories.

Bacteria↗

PubMed2001

Equilibrium and kinetics of metal ion adsorption onto a commercial H-type granular activated carbon: experimental and modeling studies.

Systematic studies on metal ion adsorption equilibrium and kinetics by a commercial H-type granular activated carbon were carried out. Titration of the carbon showed that the surface charge density decreased with an increasing pH. Higher copper adsorption was obtained with increasing solution pH and ionic strength. Metal removal was in the descending order: Cu2+ > Zn2+ approximately Co2+. Copper removal was not affected by addition of zinc or cobalt, while copper can reduce both zinc and cobalt removal. Kinetic experiments demonstrated that the copper adsorption rapidly occurred in the first 30-60 min and reached the complete removal in 3-5 h. Removal of zinc and cobalt was slightly slower than that of copper. It was found that the mass transfer is important in the metal adsorption rate. The surface complex formation model was used successfully to describe the surface change density, as well as the single- and multi-species metal adsorption equilibrium. The copper removal was due to adsorption of Cu2+, CuOH+, and CuCl+, while the zinc and cobalt uptake was due to the formation of surface metal complexes of SOM2+ and SOMOH+ (M = Zn and Co). It was found that the diffusion-control model well described the adsorption kinetics with various metal ions and pH values. Finally sensitivity analysis on the kinetic model's parameters was carried out.

Adsorption↗

PubMed2001

Molecular therapy with recombinant antisense c-myc adenovirus for human gastric carcinoma cells in vitro and in vivo.

BACKGROUND AND AIMS: This study used a recombinant antisense c-myc adenovirus (Ad-ASc-myc) to evaluate how alterations of c-myc expression in the SGC7901 human gastric carcinoma cells could influence the proliferation, apoptosis and the growth of human gastric tumors in nude mice. METHODS: The human gastric carcinoma cell line, SGC7901, treated with Ad-ASc-myc or adenovirus recombinants carrying LacZ gene (Ad-LacZ) were analyzed by using X-gal stain, MTT, DNA ladder, TUNEL assay, flow cytometric analysis, polymerase chain reaction and western blot in vitro. The tumorigenicity and experimental therapy in nude mice models were assessed in vivo. RESULTS: The Ad-ASc-myc could strongly inhibit cell growth and induce apoptosis in SGC7901 cells. The proliferation of the Ad-ASc-myc-infected SGC7901 cells was reduced by 44.1%. The mechanism of killing gastric carcinoma cells by Ad-ASc-myc was found to be apoptosis, which was detected by the use of a DNA ladder, TUNEL and flow cytometric analysis. Infection of Ad-ASc-myc in nude mice showed that all three mice failed to form tumors from the 7 to 30 day period, compared with injection of Ad-LacZ and parent SGC7901 cells. Experimental therapy on the nude mice bearing subcutaneous tumors of SGC7901 cells showed that intratumor instillation of Ad-ASc-myc inhibited the growth of the tumors. Recombinant antisense c-myc adenovirus-treated tumors were inhibited by 68.9%, compared with tumors injected with Ad-LacZ and control (LacZ and phosphate-buffered saline). CONCLUSION: The expression of Ad-ASc-myc can inhibit growth and induce apoptosis of gastric cancer cells in vitro and in vivo and thus is a potential clinical utility in gene therapy for the treatment of gastric carcinoma.

Adenoviridae↗

PubMed2001

Identification and characterization of the three chitin-binding domains within the multidomain chitinase Chi92 from Aeromonas hydrophila JP101.

The gene (chi92) encoding the extracellular chitinase of Aeromonas hydrophila JP101 has been cloned and expressed in Escherichia coli. The mature form of Chi92 is an 842-amino-acid (89.830-kDa) modular enzyme comprised of a family 18 catalytic domain, an unknown-function region (the A region), and three chitin-binding domains (ChBDs; Chi92-N, ChBD(CI), and ChBD(CII)). The C-terminally repeated ChBDs, ChBD(CI) and ChBD(CII), were grouped into family V of cellulose-binding domains on the basis of sequence homology. Chitin binding and enzyme activity studies with C-terminally truncated Chi92 derivatives lacking ChBDs demonstrated that the ChBDs are responsible for its adhesion to unprocessed and colloidal chitins. Further adsorption experiments with glutathione S-transferase (GST) fusion proteins (GST-CI and GST-CICII) demonstrated that a single ChBD (ChBD(CI)) could promote efficient chitin and cellulose binding. In contrast to the two C-terminal ChBDs, the Chi92-N domain is similar to ChiN of Serratia marcescens ChiA, which has been proposed to participate in chitin binding. A truncated derivative of Chi92 that contained only a catalytic domain and Chi92-N still exhibited insoluble-chitin-binding and hydrolytic activities. Thus, it appears that Chi92 contains Chi92-N as the third ChBD in addition to two ChBDs (ChBD(CI) and ChBD(CII)).

Aeromonas hydrophila↗

PubMed2001

Cytokine-induced p38 activation feedback regulates the prolonged activation of AKT cell survival pathway initiated by reactive oxygen species in response to UV irradiation in human keratinocytes.

A previous study has shown that UV activates the PI3K/AKT cell survival pathway while inducing cell death in human skin in vivo and cultured human keratinocytes in vitro, and yet the upstream pathway leading to the activation of AKT has not been thoroughly investigated. In this study we found that UV-induced phosphorylation of p38 and AKT in a time-dependent manner. The phosphorylation of p38 started at 5 min post UV irradiation, peaked at about 30 min, and remained elevated up to 2 h. The phosphorylation of AKT started at 15 min post UV treatment, peaked at about 1 h, and remained elevated up to 2 h. We also found that H2O2 induced phosphorylation of p38 and AKT in a time- dependent manner. Pretreatment with NAC abolished UV-induced AKT phosphorylation, suggesting the involvement of reactive oxygen species in AKT activation. Interestingly, SB203085, a known p38 inhibitor, had partially inhibited UV-induced AKT phosphorylation. Further studies showed that cytokines such as TNF-alpha and IL-1beta induced AKT phosphorylation in a time-dependent manner. Pretreatment with SB203085 inhibited IL-1beta-induced p38 and AKT phosphorylation. Collectively, our data suggest that UV activation of PI 3-kinase/AKT pathway is initiated by ROS and prolonged by feedback activation of p38 induced by released cytokines in response to UV irradiation in cultured human keratinocytes.

Apoptosis↗