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Biomedical subjects

W Q Chen

Publications and source records attributed to W Q Chen.

At least 19 recordsLinked to original sources
PubMed2005

Numerical study of the spin-Hall conductance in the Luttinger model.

We present the first numerical studies of the disorder effect on the recently proposed intrinsic spin-Hall conductance in a three dimensional lattice Luttinger model. The results show that the spin-Hall conductance remains finite in a wide range of disorder strength, with large fluctuations. The disorder-configuration-averaged spin-Hall conductance monotonically decreases with the increase of disorder strength and vanishes before the Anderson localization takes place. The finite-size effect is also discussed.

Journal Article↗
PubMed2005

Impact of occupational stress and other psychosocial factors on musculoskeletal pain among Chinese offshore oil installation workers.

AIMS: To explore the relation between psychosocial factors and musculoskeletal pain in Chinese offshore oil installation workers. METHODS: Half of all offshore workers (being a representative sample) in a Chinese oil company were invited to complete a self-administered questionnaire providing information on sociodemographic characteristics, occupational stressors, type A behaviour, social support, coping style, health related behaviour, past injuries, and musculoskeletal pain. Factor analysis was used to identify the sources of occupational stress and the domains of type A behaviour and coping style. Logistic regression analyses were used to study the relations between psychosocial factors and musculoskeletal pain in each body region. RESULTS: The prevalence of musculoskeletal pain over the previous 12 months varied between 7.5% for elbow pain and 32% for low back pain; 56% workers had at least one complaint. Significant associations were found between various psychosocial factors and musculoskeletal pain in different body regions after adjusting for potential confounding factors. Occupational stressors, in particular stress from safety, physical environment, and ergonomics, were important predictors of musculoskeletal pain, as was coping by eating behaviour. CONCLUSIONS: These observations supported the widely accepted biopsychosocial model of musculoskeletal disorders and suggested that in future studies of work related musculoskeletal disorders, psychosocial factors must be given due consideration.

Adaptation, Psychological↗
PubMed2003

Agreement between hearing thresholds measured in non-soundproof work environments and a soundproof booth.

AIMS: To study the agreement between audiometric test results measured in non-soundproof environments at the worksite, and in a soundproof booth. METHODS: In a cross sectional prevalence study on noise induced hearing loss, 885 transport workers whose hearing thresholds were measured by a standard audiometric test method in non-soundproof environments at the worksite were identified to have some hearing loss (>25 dB), and were retested in a soundproof booth. RESULTS: At 4-8 KHz, the mean of the absolute differences in hearing threshold obtained by these two methods was 2 dB or less. When the proportions of hearing loss (> or =30 dB for any frequencies at 3-8 KHz, or > or =90 dB for three low frequencies at 0.5-2 KHz, or > or =90 dB for three high frequencies at 3-6 KHz) were compared, considerable differences existed. A much better agreement was obtained when the criteria for hearing loss as measured in the field test under non-soundproof conditions were relaxed by 5 dB. At 4 KHz, the difference between the proportion of subjects with hearing loss as measured in the field and that as measured in the booth was the smallest. The kappa statistic was highest at 3 and 4 KHz. CONCLUSIONS: Audiometric test results conducted in non-soundproof environments in the field are comparable to those obtained in a soundproof environment among transport workers with a hearing loss of >25 dB. The hearing threshold at 4 KHz appears suitable for the estimation of the prevalence of hearing loss when appropriate adjustments are made in the diagnostic criteria.

Adult↗
PubMed2001

Role of taurine in regulation of intracellular calcium level and neuroprotective function in cultured neurons.

Glutamate-induced excitotoxicity has been implicated as an important mechanism underlying a variety of brain injuries and neurodegenerative diseases. Previously we have shown that taurine has protective effects against glutamate-induced neuronal injury in cultured neurons. Here we propose that the primary underlying mechanism of the neuroprotective function of taurine is due to its action in preventing or reducing glutamate-induced elevation of intracellular free calcium, [Ca(2+)](i). This hypothesis is supported by the following findings. First, taurine transport inhibitors, e.g., guanidinoethyl sulfonate and beta-alanine, have no effect on taurine's neuroprotective function, suggesting that taurine protects against glutamate-induced neuronal damage through its action on the extracellular membranes. Second, glutamate-induced elevation of [Ca(2+)](i) is reduced to the basal level upon addition of taurine. Third, pretreatment of cultured neurons with taurine prevents or greatly suppresses the elevation of [Ca(2+)](i) induced by glutamate. Furthermore, taurine was found to inhibit the influx but not the efflux of (45)Ca(2+) in cultured neurons. Taurine has little effect on the binding of [(3)H]glutamate to the agonist binding site and of [(3)H]MDL 105,519 to the glycine binding site of the N-methyl-D-aspartic acid receptors, suggesting that taurine inhibits (45)Ca(2+) influx through other mechanisms, including its inhibitory effect on the reverse mode of the Na(+)/Ca(2+) exchangers (Wu et al. [2000] In: Taurine 4: taurine and excitable tissues. New York: Kluwer Academic/Plenum Publishers. p 35-44) rather than serving as an antagonist to the N-methyl-D-aspartic acid receptors.

Animals↗
PubMed2001

Five-color-based high-information-content fingerprinting of bacterial artificial chromosome clones using type IIS restriction endonucleases.

We have developed a high-information-content fingerprinting (HICF) system for bacterial artificial chromosome (BAC) clones using a Type IIS restriction endonuclease, HgaI, paired with a Type II restriction endonuclease, RsaI. In the method described, unknown five-base overhangs generated with HgaI are partially or fully sequenced by modified fluorescent dideoxy terminators. Using an in-lane size standard labeled with a fifth dye, fragments are characterized by both the size and the sequence of its terminal one to five bases. The enhanced information content associated with this approach significantly increases the accuracy and efficiency of detecting shared fragments among BAC clones. We have compared data obtained from this method to predicted HICF patterns of 10 fully sequenced BACs. We have further applied HICF to 555 BAC clones to assemble contigs spanning 16p11.2 to 16p13.1 of human chromosome 16.

Chromosomes, Artificial, Bacterial↗
PubMed2001

Effects of hepatocyte growth-promoting factor and panax notoginseng saponins on intrasplenic hepatocellular autotransplantation.

AIM: To increase the weight of liver tissue mass present in spleen and to shorten the regeneration period of transplanted hepatocytes by stimulating DNA synthesis and protection against ischemic-reperfusion injury. METHODS: Hepatocyte growth-promoting factor (PHGF) and panax notoginseng saponins (PNGS) were used after intrasplenic hepatocellular autologous transplantation (IHAT) with 70 % partial hepatectomy. Histological examinations were carried out under both light and electron microscopy and content of ALT in hepatized spleen homogenate was investigated 2 weeks after transplantation. Furthermore, 99mTc diethyl-iminodiacetic acid (99mTc-HIDA) splenic scintiphotography was carried out and proliferation index of transplanted hepatocytes was detected by flow cytometry at the 12th week after operation. RESULTS: (1) Hepatocellular degeneration was slightly less in group B [intrasplenic hepatocyte autologous transplantation (IHAT) + PNGS 25 mg/kg, im, qd] vs the control group (group C, IHAT without drugs) at the 2nd week after transplantation, and the ALT content of group B (928 U/g +/- 268 U/g) was higher than that of group C (639 U/g +/- 138 U/g, P < 0.01). (2) At the 12th week, hepatocellular regeneration in group A (IHAT + PHGF 5 mg/kg, im, qd) was obviously better than that in group C, and the ALT content (2325 U/g +/- 401 U/g ), the radioactivity accumulation of 99mTc-HIDA (58 Bq +/- 18 Bq), and proliferation index (3.8 % +/- 0.4 %) of group A were all higher than those of control (P < 0.05). CONCLUSION: PHGF has effects in increasing the weight of liver tissue grown in spleen and shortening the regeneration period of the transplanted hepatocytes, while PNGS has certain effects on protecting the hepatocytes against ischemic reperfusion injury in the early stage of transplantation.

Animals↗
PubMed2001

[Effect of songling xuemaikang capsule combined with captopril on quality of life in primary hypertension patients].

OBJECTIVE: To compare the hypotensive effects of captopril and combined medication of Songling Xue-maikang Capsule (SXC) with captopril on quality of life (QOL) in treating primary hypertension patients. METHODS: For 166 hypertension patients, a perspective randomized double blind study was performed with both sexes, aged 42-78 years, blood pressure (BP) ranged > or = 140/90 mmHg and < or = 200/110 mmHg. Patients were randomly divided into two groups: captopril group and combined medication group. Each patient should answer the QOL questionnaire independently before and after experiment. 60 age-matched normotensive subjects without chronic diseases served as control. RESULTS: Both hypertension groups showed an improvement of BP and QOL after treatment, but the combined medication group had a higher score in sense of well being, physical symptom-signs, work performance and life satisfaction than the captopril group had. CONCLUSION: Combined medication of captopril and SXC had better effect than captopril alone either in lowering BP or in improving QOL of primary hypertension patients.

Adult↗
PubMed2000

Polyhydroxylated C(60), fullerenols, as glutamate receptor antagonists and neuroprotective agents.

Derivatives of C(60) have been shown to be effective free radical scavengers. Hence, many of the biological functions of fullerene are believed to be due to their antioxidant properties. Here we present evidence to show that fullerenols, that are caged fullerene oxides, exert their neuroprotective functions by blocking glutamate receptors and lowering the intracellular calcium, [Ca(2+)](i). In neuronal cultures, fullerenols reduce glutamate-induced neurotoxicity by about 80% at 50microM. No significant effect was observed on H(2)O(2)/Fe(2+)-induced neurotoxicity under the same conditions. Fullerenols were found to inhibit glutamate receptor binding in a dose-dependent manner inhibiting 50% of glutamate binding at 50 microM. Furthermore, AMPA receptors were found to be more sensitive to fullerenols than NMDA and KA receptors. On the other hand, GABA(A) receptors and taurine receptors were not significantly affected by fullerenols at the same concentrations used, suggesting that fullerenols inhibit primarily the glutamate receptors. In addition, fullerenols were also found to lower glutamate (Glu) receptor-induced elevation of [Ca(2+)](i), suggesting that the underlying mechanism of neuronal protective function of fullerenols is likely due to its ability to block the glutamate receptors and to reduce the level of [Ca(2+)](i).

Animals↗
PubMed2000

Alleviation of pre-exposure to low-dose 16O8+ ion on mouse testicular histological damage induced by subsequent high-dose irradiation.

The testes of the B6C3F1 hybrid strain mice were irradiated with 0.05 Gy of 16O8+ ion as the pre-exposure dose (D1), and were then irradiated with 2 Gy of 16O8+ ion as challenging radiation dose (D2) at 4 h after per-exposure. Testicular morphology was observed by light microscope at 35th day after radiation. The results showed that irradiation of mouse testes with 2 Gy of 16O8+ ion significantly impaired, mainly reduction of tubule diameter and decrease or loss of germ cells in various developing stages, especially spermatogenic elements. Pre-exposure to a low-dose (0.05 Gy) of 16O8+ ion significantly alleviated above mentioned damage on testicular morphology induced by subsequent a high-dose (2 Gy) radiation.

Animals↗
PubMed1999

Effects of 16O+6 ion irradiation on human sperm spontaneous chemiluminescence, motility, acrosome reaction and viability in vitro.

Effects of 16O+6 ion irradiation with different doses on human sperm spontaneous chemiluminescence (SCL), motility, acrosome reaction (AR) and viability were examined. Spermatozoa were irradiated with 0, 0.25, 0.5, 1, 2, 4, 8, 16, 32, or 64 Gy 16O+6 ion beam at the energy of 3.17 MeV/u. After irradiation, samples were analyzed by SCL measurement at 1, 2 and 3 h of incubation; motility was determined by the transmembrane migration method within 2 h of incubation; the percentage of AR and viability was evaluated by the triple-stain technique at 3.5 h of incubation. The results showed: sperm SCL was significantly increased with irradiation doses and the lowest effective dose was 0.5 Gy; compared with controls, the transmembrane migration ratio of spermatozoa progressively elevated with irradiation doses at 0.5, 1, and 2 Gy; the percentage of sperm AR markedly increased in 0.5-4 Gy irradiation and the optimal dose was 2 Gy, and then significant decreased with further increase of irradiation doses; the viability had no significant change within 0.25-8 Gy, but was progressively decreased at 16, 32 and 64 Gy. These data suggested that heavy ion at low doses increased motility and AR, whereas had deleterious effects at higher doses, which are associated with free radical reactions induced by heavy ion irradiation.

Acrosome Reaction↗
PubMed1998

Chromosomal aberrations induced by 12C6+ heavy ion irradiation in spermatogonia and spermatocytes of mice.

The testes of Kun-Ming strain mice were radiated with different doses of 12C6+ ion or 60Co gamma-ray. Chromosomal aberrations induced in spermatogonia and spermatocytes were analyzed by the air-drying method. The relative biological effectiveness (RBE) of 12C6+ ion was calculated with respect to 60Co gamma-ray for the induction of chromosomal aberrations. The 12C6+ ion and 60Co gamma-ray dose-response relationships for chromosomal aberrations were plotted by linear quadratic models. The results showed that there was an increase in frequency of chromosomal aberrations in all the treated groups compared to controls. The RBE values were 1.67 for aberrations of spermatogonia and 1.66 for aberrations of spermatocytes for a dose of 2.0 Gy. Moreover, a different distribution of the various types of aberrations has been found for 12C6+ ion and 60Co gamma-ray irradiations. The dose-response relationships for 12C6+ ion and 60Co gamma-ray exhibited negative curvature in both spermatogonia and spermatocytes groups: the frequencies of aberrations increased sharply at low doses and exhibited less sharp increases for higher doses, which may be related to an interaction between the chromosomal damage and a block in cell cycle. Our results may provide useful information for the assessment of genetic risks of humans exposed to heavy ions.

Animals↗
PubMed1998

Effects of pre-exposure of mouse testis with low-dose (16)O8+ ions or 60Co gamma-rays on sperm shape abnormalities, lipid peroxidation and superoxide dismutase (SOD) activity induced by subsequent high-dose irradiation.

PURPOSE: To investigate the effects of pre-exposure of mouse testis with low-doses of (16)O8+ ions or 60Co gamma-rays on sperm shape abnormalities, lipid peroxidation and superoxide dismutase (SOD) activity induced by subsequent high-dose irradiation. MATERIALS AND METHODS: Testes of the B6C3F1 hybrid strain mice were pre-irradiated with 0.05 Gy of (16)O8+ ions or 60Co gamma-rays and then after 4 h given a test irradiation with 2 Gy of the same radiation type. SOD activity and thiobarbituric acid reactive substances (TBARS) in the testes were determined by spectrophotometric and TBA methods respectively at 4 h after irradiation. Testis weight, sperm count and sperm morphology were analysed at day 35 after irradiation. RESULTS: Compared with controls, there was a significant increase in SOD activity and a significant decrease in TBARS level of pretreated testes. Testis weight loss, sperm count reduction and sperm abnormalities were significantly lower in the pretreated testes. The bioeffects of a 2 Gy dose of (16)O8+ ions relative to 60Co gamma-rays were 1.84 +/- 0.28 for testis weight, 1.22 +/- 0.25 for sperm count and 1.29 +/- 0.10 for sperm abnormalities. CONCLUSIONS: These data suggest that pre-exposure of testes with a low dose of heavy ions or gamma-rays renders the organ more resistant to subsequent high-dose irradiation. The increase of SOD activity and the decrease of lipid peroxidation levels induced by low-dose ionizing irradiation may be involved in this resistance. The effects with heavy ion irradiation were greater than with gamma-rays.

Animals↗
PubMed1997

Enhanced anti-tumor effect of an IFN-gamma-EGF fusion protein.

The novel fusion proteins harboring human or mouse interferon combined with epidermal growth factor receptor binding domain were constructed using methods of genetic and protein engineering. The fusion proteins were assayed to retain complete antiviral activities. The EGF receptor binding moiety of the fusion proteins exhibited competitive binding against 125I-EGF for EGF receptors on A431 cells. The fusion proteins were shown to be more potent in inhibiting the growth of cultured target carcinoma cells than interferon-gamma alone. Experimental data derived from mouse B16 malignant melanoma models indicates that the weight of tumor in mice treated with IFN fusion proteins was significantly smaller than that of mice treated with interferon-gamma alone. The work here is unprecedented in the world and provides a reliable evidence to support the upcoming clinical employment of a class of interferons that specifically target tumor cell.

Amino Acid Sequence↗
PubMed1996

The value of Tc-99m MIBI SPECT during isosorbide dinitrate infusion in assessment of viable myocardium in patients with myocardial infarction.

Tc-99m MIBI myocardial SPECT has shown promise for evaluation of coronary artery disease. But its role in predicting myocardial viability is still under investigation. The purpose of this study was to evaluate the value of Tc-99m MIBI myocardial SPECT during isosorbide dinitrate (ISDN) infusion in the assessment of myocardial viability. Thirty-seven patients with previous myocardial infarction (the infarct age ranged from < or = 30 days to 900 days) were studied, of them 13 patients had Tc-99m MIBI studies before and after coronary artery bypass grafting (CABG). The results showed that out of 134 segments with hypoperfusion at resting SPECT, 56 segments (41.8%) had an increase in Tc-99m MIBI uptake during ISDN infusion. Among them, 17 segments (30.4%) were normalized, 6 segments (10.7%) were significantly improved and 33 segments (58.9%) were improved. The degree of improvement in perfusion was related to the age of the myocardial infarction. In 13 patients with CABG, of 31 segments with improvement in perfusion post CABG, 25 segments (80.6%) showed perfusion improvement during ISDN infusion, and of 28 segments with improved wall motion post CABG, 23 segments (82.1%) showed improvement in perfusion during ISDN infusion. Tc-99m MIBI SPECT during ISDN infusion may therefore be a useful approach for assessing myocardial viability.

Adult↗