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Biomedical subjects

H Chen

Publications and source records attributed to H Chen.

At least 55 records · Page 3Linked to original sources
PubMed2006

Area-level socio-economic status and health status among adults with asthma and rhinitis.

Socio-economic status (SES) may affect health status in airway disease at the individual and area level. In a cohort of adults with asthma, rhinitis or both conditions, questionnaire-derived individual-level SES and principal components analysis (PCA) of census data for area-level SES factors were used. Regression analysis was utilised to study the associations among individual- and area-level SES for the following four health status measures: severity of asthma scores and the Short Form-12 Physical Component Scale (SF-12 PCS) (n = 404); asthma-specific quality of life (QoL) scores (n = 340); and forced expiratory volume in one second (FEV1) per cent predicted (n = 218). PCA yielded a two-factor solution for area-level SES. Factor 1 (lower area-level SES) was significantly associated with poorer SF-12 PCS and worse asthma QoL. These associations remained significant after adding individual-level SES. Factor 1 was also significantly associated with severity of asthma scores, but not after addition of the individual-level SES. Factor 2 (suburban area-level SES) was associated with lower FEV1 per cent predicted in combined area-level and individual SES models. In conclusion, area-level socio-economic status is linked to some, but not all, of the studied health status measures after taking into account individual-level socio-economic status.

Adolescent↗
PubMed2006

Laboratory evaluation of flight performance of the plum curculio (Coleoptera: Curculionidae).

Flight performance of laboratory-reared adults of the plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), was investigated under controlled conditions by using a flight mill system. Across all insects tested (n=198), median values of total distance traveled, total flight time, and maximum uninterrupted flight time were 122.7 m day(-1), 23.5 min day(-1), and 2.0 min, respectively. The latter result indicates that flight occurred primarily in short bursts. Although females had a significantly higher body mass than males, there were no significant differences in flight performance between the two sexes. Flight during the first 24-h test period (especially the first 6 h) was dominated by escape behavior, i.e., elevated levels of activity presumably associated with attempts by the insects to regain freedom of movement; during the second 24 h, flight activity was very limited throughout the late morning and afternoon, increased around sunset, and remained high during the night. All flight performance variables decreased linearly and significantly with insect age over the age range tested (2-16 d after emergence). Nutritional status also had a significant effect, whereby insects that had been provided with apples as a food source for 2 d after emergence showed considerably improved flight performance compared with those that had been given no food or only water during the same period. There was no significant effect of mating status on flight performance of male or female insects.

Animals↗
PubMed2006

Modeling biodegradation of toluene in rotating drum biofilter.

Rotating drum biofilters (RDBs) are cost-effective for control of emissions of volatile organic compounds (VOCs) from waste gas streams. In this paper, a dynamic mathematical model is presented which simulates and predicts the variation in performance of a multi-layer RDB with time on the basis of the two-film theory. The model takes into account factors including biofilm growth and biomass loss, and a changing biofilm surface area and thickness assuming quasi-steady-state conditions in the two-phase system and uniform bacterial population. Toluene was assumed to be the only rate-limiting substrate. The model equations for the gas-phase mass balance and biofilm growth were solved using MATLAB based on the fourth-fifth-order Runge-Kutta technique, and the concentration profiles in the biofilms were obtained using the method of orthogonal collocation. Simulation results showed that the toluene removal efficiency decreased with increased toluene loading or increased duration of operation of the biofilter. Calculation results were compared to the experimental results, which demonstrated that the dynamic model provided a good simulation of the performance of the biofilter.

Biodegradation, Environmental↗
PubMed2006

Development of a recombinant fowlpox virus vector-based vaccine of H5N1 subtype avian influenza.

The genetic stability of the recombinant fowlpox virus (named rFPV-HA-NA) was confirmed by serial passage on chicken embryo fibroblast (CEF) cells. The immune efficacy, safety, the minimum immunising dose, the time of immunity induced and the immune duration of the vector-based vaccine was evaluated in specific-pathogen-free (SPF) chickens. The recombinant virus vaccine containing 100 plaque form units (PFU) could induce complete protection against challenge with H5N1 highly pathogenic avian influenza virus (HPAIV). The immune efficacy, protecting chickens from clinical signs and death after challenge, was obtained one week after the immunisation with this vaccine. Protective immunity could last for 40 weeks post-immunisation. So the recombinant fowlpox vaccine is a safe and highly effective gene engineering vaccine candidate, and will be used to prevent H5 subtype avian influenza in the future.

Animals↗
PubMed2006

VEGF induces phosphorylation of STAT3 through binding VEGFR2 in ovarian carcinoma cells in vitro.

VEGF plays a key role in ovarian carcinoma. Recent studies have shown that expressions of VEGF and its receptors were correlated with signal tranducer phosphorylation and activators of transcription 3(p-STAT3) in ovarian carcinoma. The aim of this study was to investigate the effects of STAT3 phosphorylation on VEGF signaling pathways in ovarian carcinoma cells. We selected an ovarian carcinoma cell line Caov-3 as a target cell that co-expressed VEGFR2 and p-STAT3. We detected expressions of p-STAT3 in Caov-3 induced by VEGF with different concentrations and for different effect times by immunocytochemistry and Western Blot. A concentration of 50 ng/ml VEGF was enough to increase phosphorylation of STAT3, and at 30 min, the p-STAT3 level reached the peak and showed nuclear translocation of p-STAT3 from the cytoplasm to the nucleus. These effects could be overcome by a small peptide (ATWLPPR) specific for VEGFR2. Taken together, VEGF-induced phosphorylation and nuclear translocation of STAT3 and ATWLPPR could effectively block the VEGF effects, suggesting that phosphorylation of STAT3 participates in VEGF signal transduction via VEGFR2 in ovarian carcinoma cells.

Blotting, Western↗
PubMed2005

Measurement of the two-loop lamb shift in lithiumlike U89+.

Using the SuperEBIT electron beam ion trap, we have measured the 2s(1/2)-2p(1/2) transitions in U88+ and U89+. The measured value of 280.645 +/- 0.015 eV for Li-like U89+ improves the available precision by nearly an order of magnitude and establishes a new benchmark for testing the total QED contribution to the transition energy within a fractional accuracy of 3.6 x 10(-4). We infer a value for the 2s two-loop Lamb shift in U89+ of -0.23 eV, from which we estimate a value of -1.27 eV for the 1s two-loop Lamb shift in U91+.

Journal Article↗
PubMed2005

Glutathione S-transferase polymorphisms and ovarian cancer treatment and survival.

OBJECTIVE: Members of the glutathione S-transferase (GST) family have been shown to have functional polymorphisms that may affect drug metabolism and influence the effects of chemotherapy and survival from cancer. GSTM1, GSTT1, and GSTP1 genotypes were evaluated for their role in ovarian cancer treatment and survival. METHODS: DNA was extracted from tumor tissues of 215 patients diagnosed with primary epithelial ovarian cancer. GSTM1 and GSTT1 genotypes were determined by multiplex PCR; GSTP1 genotypes were assessed with PCR-RFLP. Associations between GST polymorphisms and risk of ovarian cancer progression or death were analyzed using Cox proportional hazards regression; subgroups of patients receiving different chemotherapeutics were also evaluated. RESULTS: GST polymorphisms were not found to be associated with patient or tumor characteristics or response to treatment. However, GSTM1 null patients were less likely to have disease progression (HR: 0.65, 95% CI: 0.43-0.99) or to die (HR: 0.68, 95% CI: 0.45-1.03) compared to patients with GSTM1. Patients with GSTM1 null and GSTP1 ile/val or val/val (reduced function) had a further reduction in risk of disease progression compared to patients with GSTM1 or GSTP1 ile/ile (HR: 0.42, 95% CI: 0.24-0.75). A similar association was also suggested for overall survival (HR: 0.61, 95% CI: 0.36-1.05). Subgroup analyses indicated that the effects of GST on survival were more pronounced among patients treated with specific chemotherapeutics. CONCLUSION: These findings support the idea that reduced GST function may improve ovarian cancer survival after post-operative chemotherapy; evaluation of GST functional polymorphisms may help to predict ovarian cancer prognosis.

Adult↗
PubMed2005

Temperature determination using Kalpha spectra from M -shell Ti ions.

The compact multipulse terawatt (COMET) laser facility at LLNL was used to irradiate Al-coated 2-50 microm Ti foils with approximately 10(19) W cm(-2) , 500 fs, 3-6 J laser pulses. Laser-plasma interactions on the front side of the target generate hot electrons with sufficient energy to excite inner-shell electrons in Ti, creating Kalpha emission which has been measured using a focusing spectrometer with spatial resolution aimed at the back surface of the targets. The spatial extent of the emission varies with target thickness. The high spectral resolution (lambda/Deltalambda approximately equal to 3800) is sufficient to measure broadening of the Kalpha emission feature due to the emergence of blueshifted satellites from ionized Ti in a heated region of the target. A self-consistent-field model is used to spectroscopically diagnose thermal electron temperatures up to 40 eV in the strongly coupled Ti plasmas.

Journal Article↗
PubMed2005

Data-driven docking: HADDOCK's adventures in CAPRI.

We have shown previously that given high-resolution structures of the unbound molecules, structure determination of protein complexes is possible by including biochemical and/or biophysical data as highly ambiguous distance restraints in a docking approach. We applied this method, implemented in the HADDOCK (High Ambiguity Driven DOCKing) package (Dominguez et al., J Am Chem Soc 2003;125:1731-1737), to the targets in the fourth and fifth rounds of CAPRI. Here we describe our results and analyze them in detail. Special attention is given to the role of flexibility in our docking method and the way in which this improves the docking results. We describe extensions to our approach that were developed as a direct result of our participation in CAPRI. In addition to experimental information, we also included interface residue predictions from PPISP (Protein-Protein Interaction Site Predictor; Zhou and Shan, Proteins 2001;44:336-343), a neural network method. Using HADDOCK we were able to generate acceptable structures for 6 of the 8 targets, and to submit at least 1 acceptable structure for 5 of them. Of these 5 submissions, 3 were of medium quality (Targets 10, 11, and 15) and 2 of high quality (Targets 13 and 14). In all cases, predictions were obtained containing at least 40% of the correct epitope at the interface for both ligand and receptor simultaneously.

Algorithms↗
PubMed2005

Role of domestic ducks in the propagation and biological evolution of highly pathogenic H5N1 influenza viruses in Asia.

Wild waterfowl, including ducks, are natural hosts of influenza A viruses. These viruses rarely caused disease in ducks until 2002, when some H5N1 strains became highly pathogenic. Here we show that these H5N1 viruses are reverting to nonpathogenicity in ducks. Ducks experimentally infected with viruses isolated between 2003 and 2004 shed virus for an extended time (up to 17 days), during which variant viruses with low pathogenicity were selected. These results suggest that the duck has become the "Trojan horse" of Asian H5N1 influenza viruses. The ducks that are unaffected by infection with these viruses continue to circulate these viruses, presenting a pandemic threat.

Animals↗
PubMed2005

Electromagnetically induced magnetochiral anisotropy in a resonant medium.

Chirality has been extensively studied for well over a century, and its potential applications range from optics to chemistry, medicine, and biology. Ingenious experiments have been designed to measure this naturally small effect. Here we discuss the possibility of producing a medium having a large chiral effect by using the ideas of coherent control. The coherent fields resonant with appropriate transitions in atomic or molecular systems can be used to manipulate the optical properties of a medium. We demonstrate experimentally very large magnetochiral anisotropy by using electromagnetic fields in atomic Rb vapors.

Journal Article↗
PubMed2005

Design, synthesis and in vitro and in vivo antitumor activities of novel beta-carboline derivatives.

To further our SAR study on the chemistry and antitumor activity/neurotoxicity of beta-carboline alkaloids, several series of beta-carboline derivatives with various substituents were designed and synthesized from the starting material l-tryptophan on the basis of harmine chemical structure. Cytotoxic activities of these compounds were investigated in vitro. The results showed that some beta-carboline derivatives had significant cytotoxic activities against human tumor cell lines. Among all the synthesized beta-carboline derivatives, the compounds 27, 28 and 32, having a benzyl substituent at both position-2 and 9, respectively, were found to be the most potent compounds with IC50 value lower than 50 microM against all human tumor cell lines examined. Acute toxicities and antitumor activities of the selected beta-carboline derivatives in mice were also evaluated. The results demonstrated that a benzyl substituent at position-2 increased the antitumor activity as well as acute toxicity significantly. However an (ethoxycarbonyl)amino substituent at position-3 reduced the acute toxicity as well as antitumor activity remarkedly. These data suggested that (1) the antitumor potencies of beta-carboline derivatives were enhanced by the introduction of benzyl substituent into the position-2; (2) the acute toxicity of beta-carboline derivatives reduced dramatically by the introduction of an appropriate substituent into the position-3 and 9; (3) the beta-carboline structure might be an important basis for the design and synthesis of new antitumor drugs with significant antitumor activity and low toxicity.

Animals↗
PubMed2005

Physical activity and the risk of Parkinson disease.

OBJECTIVE: To investigate whether greater physical activity is associated with a lower risk of Parkinson disease (PD). METHODS: The authors prospectively followed 48,574 men and 77,254 women who provided information on physical activity in 1986 or in early adulthood. During the follow-up, a total of 252 (male) and 135 (female) incident PD cases were identified. RESULTS: In men, greater baseline physical activity was associated with a lower PD risk; compared with the lowest quintile, the multivariate relative risk (RR) of PD for the highest quintile was 0.7 (95% CI 0.5 to 1.1; p value, test for trend = 0.007), and the inverse association was still present after excluding the first 10 years of follow-up (RR = 0.5; p value, test for trend = 0.02). Further, strenuous exercise in early adult life was also inversely related to PD risk in men: compared with men who regularly exercised < or =2 months/year, those with > or =10 months of strenuous exercise had a 60% lower PD risk (RR = 0.4; p value, test for trend = 0.005). In women, physical activity assessed at baseline was not related to PD risk, whereas strenuous exercise in early adulthood tended to be inversely related to PD risk later in life (highest vs lowest categories, RR = 0.5, 95% CI 0.2 to 1.4; p value, test for trend = 0.06). CONCLUSION: This study suggests either that higher levels of physical activity may lower the risk of Parkinson disease (PD) in men or that men predisposed to PD tend to avoid strenuous physical activity in their early adult years.

Adult↗
PubMed2005

Expression of endothelial nitric oxide synthase traffic inducer in the placentas of women with pre-eclampsia.

OBJECTIVE: To investigate the expression of endothelial nitric oxide synthase traffic inducer (NOSTRIN) in the placenta of women with pre-eclampsia (PE) and discuss its role in the pathogenesis of PE. METHODS: Western blot analysis was used to detect the expression of NOSTRIN and endothelial nitric oxide synthase (eNOS). The activity of eNOS in placental tissue was assayed by spectrophotometry. Serum and placental NO(2)/NO(3), the stable metabolic end product of NO, was measured using nitrate reductase. RESULTS: Western blot analysis showed that the protein level of NOSTRIN was significantly higher in women with PE than in the control group (P<0.01). However, no significant difference between groups was observed in the expression of placental eNOS (P>0.05). The activity of eNOS was significantly decreased in women with PE (13.727+/-3.58 U/mg) compared with the control group (21.69+/-3.84 U/mg) (P<0.01). The placental levels of NO(2)/NO(3) were significantly lower in women with PE (27.53+/-8.51 micromol/mg) than in the control group (44.38+/-9.59 micromol/mg) (P<0.01). The levels of serum NO(2)/NO(3) were significantly lower in women with PE (48.56+/-8.49 micromol/L) than in the control group (65.37+/-9.61 micromol/L) (P<0.01). A significant negative correlation existed between the expression of NOSTRIN protein and the activity of eNOS in the placental tissues of women with PE (r=-0.57, P<0.01). CONCLUSION: The level of NOSTRIN expression in the placental tissues of women with PE is increased and is negatively correlated with the activity of eNOS-which may play an important role in the pathogenesis of PE.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Late developing C4d-positive humoral renal allograft rejection associated with withdrawal of mycophenolate mofetil.

In renal transplantation, C4d-positive acute humoral rejection (AHR) usually develops in the early stage posttransplantation. It is clear C4d can be detected late after the operation, when it is associated with chronic renal allograft rejection. We report a case of a renal allograft recipient who experienced C4d-positive acute renal allograft rejection associated with withdrawal of mycophenolate mofetil (MMF) at 10 months after transplantation. This 21-year-old single male patient received his first cadaveric renal allograft under immunosuppression with cyclosporine, MMF, and prednisolone. The serum creatinine recovered to the normal range within 4 days. A protocol biopsy performed at 1 month after transplantation revealed no signs of rejection. The graft function was stable until 10 months postoperation, when MMF was converted to mizoribin. Three days later a biopsy showed a C4d-positive rejection. Patient had no response to the MMF combined with tacrolimus and steroid bolus therapy, which generally improves 85% of AHR among Chinese. He finally returned to dialysis. Our report suggested that C4d positive AHR may occur late after transplantation. MMF is important to suppress the body's humoral response to allograft; when MMF was converted to a weaker immunosuppressant, the dose of the other immunosuppressants (cyclosporine for example) must be adjusted properly.

Acute Disease↗
PubMed2005

Detection of porcine circovirus type 2, porcine parvovirus and porcine pseudorabies virus from pigs with postweaning multisystemic wasting syndrome by multiplex PCR.

Multiplex PCR was established to detect porcine circovirus type 2 (PCV-2), porcine parvovirus (PPV) and porcine pseudorabies virus (PRV) and applied to samples from 137 piglets exhibiting clinical signs of postweaning multisystemic wasting syndrome (PMWS). PCV-2 DNA was detected from all samples. Moreover, 43 samples were positive for PPV but negative for PRV; 11 samples were positive for PRV but negative for PPV; and 35 samples were positive both for PPV and PRV. These results suggests that PCV-2 co-infection with PRV and PPV may play an important role in PMWS. Also, multiplex PCR is an appropriate candidate method for diagnosis of PCV-2, PRV and PPV simultaneously in field cases.

Animals↗
PubMed2005

Pegfilgrastim after high-dose chemotherapy and autologous peripheral blood stem cell transplant: phase II study.

Pegfilgrastim is equivalent to daily filgrastim after standard dose chemotherapy in decreasing the duration of neutropenia. Daily filgrastim started within 1-4 days after autologous stem cell transplant (ASCT) leads to significant decrease in time to neutrophil engraftment. We undertook a study of pegfilgrastim after high-dose chemotherapy (HDC) and ASCT. In all, 38 patients with multiple myeloma or lymphoma, eligible to undergo HDC and ASCT, were enrolled. Patients received a single dose of 6 mg pegfilgrastim subcutaneously 24 h after ASCT. There were no adverse events secondary to pegfilgrastim. All patients engrafted neutrophils and platelets with a median of 10 and 18 days, respectively. The incidence of febrile neutropenia was 49% (18/37). Neutrophil engraftment results were compared to a historical cohort of patients who received no growth factors or prophylactic filgrastim after ASCT. Time to neutrophil engraftment using pegfilgrastim was comparable to daily filgrastim and was shorter than in a historical group receiving no filgrastim (10 vs 13.7 days, P<0.001). Pegfilgrastim given as a single fixed dose of 6 mg appears to be safe after HDC and ASCT. It accelerates neutrophil engraftment comparable to daily filgrastim after ASCT. Pegfilgrastim may be convenient to use in outpatient transplant units.

Adult↗