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Biomedical subjects

S C Wu

Publications and source records attributed to S C Wu.

At least 19 recordsLinked to original sources
PubMed2006

Trace metal contamination of sediments in an e-waste processing village in China.

This study examined trace metal contamination of sediments in Guiyu, China where primitive e-waste processing activities have been carried out. It was found that some river sediments in Guiyu were contaminated with Cd (n.d.-10.3mg/kg), Cu (17.0-4540mg/kg), Ni (12.4-543mg/kg), Pb (28.6-590mg/kg), and Zn (51.3-324mg/kg). The (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios of the Pb-contaminated sediments of Lianjiang (1.1787+/-0.0057 and 2.4531+/-0.0095, respectively) were lower than those of Nanyang River (1.1996+/-0.0059 and 2.4855+/-0.0082, respectively), indicating a significant input of non-indigenous Pb with low (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios. Copper, Pb and Zn in the non-residual fractions noticeably increased in the contaminated sediments compared to those in the uncontaminated sediments. A genuine concern is associated with potential transport of the contaminated sediments downstream and enhanced solubility and mobility of trace metals in the non-residual fractions.

Cadmium↗
PubMed2006

Distribution of polycyclic aromatic hydrocarbons in soils at Guiyu area of China, affected by recycling of electronic waste using primitive technologies.

The concentration, distribution, profile and possible source of polycyclic aromatic hydrocarbons (PAHs) in soil were studied in Guiyu, an electronic waste (E-waste) recycling center, using primitive technologies in Southeast China. Sixteen USEPA priority PAHs were analyzed in 49 soil samples (0-10 cm layer) in terms of individual and total concentrations, together with soil organic matter (SOM) concentrations. The concentrations of a sum of 16 PAHs ranged from 44.8 to 3206 microgkg(-1) (dry weight basis), in the descending order of E-waste open burning sites (2065 microgkg(-1))>areas near burning sites (851microgkg(-1))>rice fields (354 microgkg(-1))>reservoir areas (125microgkg(-1)). The dominant PAHs were naphthalene, phenanthrene and fluoranthene, which were mainly derived from incomplete combustion of E-waste (e.g. wire insulations and PVC materials), and partly from coal combustion and motorcycle exhausts. All individual and total PAH concentrations were significantly correlated with SOM except for naphthalene and acenaphthylene. Principal component analysis was performed, which indicated that PAHs were mainly distributed into three groups in accordance with their ring numbers and biological and anthropogenic source. In conclusion, PAH concentrations in the Guiyu soil were affected by the primitive E-waste recycling activities.

China↗
PubMed2006

Influence of bacteria on Pb and Zn speciation, mobility and bioavailability in soil: A laboratory study.

A soil column experiment was carried out to investigate the effects of inoculation of bacteria on metal bioavailability, mobility and potential leachability through single chemical extraction, consequential extraction and in situ soil solution extraction technologies. Results showed that bacteria inoculated, including Azotobacter chroococcum, Bacillus megaterium and Bacillus mucilaginosus, may pose both positive and negative impacts on bioavailability and mobility of heavy metals in soil, depending on the chemical nature of the metals. The activities of bacteria led to an increase of water dissolved organic carbon (DOC) concentration and a decrease of pH value, which enhanced metal mobility and bioavailability (e.g. an increase of water-soluble and HOAc-soluble Zn). On the other hand, bacteria could immobilize metals (e.g. a great reduction of water-soluble Pb) due to the adsorption by bacterial cell walls and possible sedimentation reactions with phosphate or other anions produced through bacterial metabolism.

Adsorption↗
PubMed2006

The HIV related risks among men having sex with men in rural Yunnan, China: a qualitative study.

OBJECTIVES: To explore the characteristics and issues specific to HIV related risk behaviours among men who have sex with men (MSM) in rural China. METHOD: Qualitative study using semistructured in-depth interviews in Dali prefecture, Yunnan. 24 informants recruited through a local MSM network, snowballing and by word of mouth. The main outcome measures were themes identified as increased exposures and risks to HIV. RESULTS: Risk behaviour, social stigma, one child policy and concepts of traditional Chinese medicine (TCM) had significant roles in the spread of HIV in rural China. Many MSM lead a life with double identities in China and condom use was found to be variable with attempts to "rationalise" the risky behaviour being its major determining factor. Health seeking behaviours of genitourinary problems were infrequent and illogical, which were further held back by the existing healthcare system and lack of sensitivity expressed by the health professionals. CONCLUSIONS: Clear education messages to the general public while raising awareness among health professionals of the health risks and needs in MSM are essential in the prevention of the current HIV epidemic.

Adult↗
PubMed2005

Effects of inoculation of plant growth-promoting rhizobacteria on metal uptake by Brassica juncea.

A greenhouse study was carried out with Brassica juncea to critically evaluate effects of bacterial inoculation on the uptake of heavy metals from Pb-Zn mine tailings by plants. Application of plant growth-promoting rhizobacteria, including nitrogen-fixing bacteria and phosphate and potassium solubilizers, might play an important role in the further development of phytoremediation techniques. The presence of these beneficial bacteria stimulated plant growth and protected the plant from metal toxicity. Inoculation with rhizobacteria had little influence on the metal concentrations in plant tissues, but produced a much larger above-ground biomass and altered metal bioavailability in the soil. As a consequence, higher efficiency of phytoextraction was obtained compared with control treatments.

Biodegradation, Environmental↗
PubMed2005

Structural transitions in two-dimensional hard-sphere systems.

We spread randomly noncharged steel particles (diameter, 1.59 mm) on a silicon wafer to form a two-dimensional hard-sphere system. The particle structure versus the particle coverage was monitored. We observed the particle structural transition from liquidlike to triangular-lattice crystal-like with increasing particle coverage by analyzing the particle structure factor. The particle coverage at which the structural transition occurs was quantified by the curves of S(max) (A) and G6 (A); S(max) is the amplitude of the first peak of the structure factor (depicting the particle positional order), and G6 is the bond orientation order parameter. We also conducted a Monte Carlo simulation study. The Monte Carlo simulation results show good agreement with the experimental results at low particle area fractions. However, at high area fractions, the experimentally observed particle structure is less organized than that generated by simulations.

Journal Article↗
PubMed2003

Changes in soil microbial biomass and Zn extractability over time following zn addition to a paddy soil.

A laboratory incubation study was conducted using a paddy soil spiked with two quantities of Zn as soluble Zn(NO3)2 and unamended controls. Three single extractants (1 M ammonium acetate (pH 7.0), 0.43 M acetic acid and 0.05 M EDTA) were used to assess the bioavailability of Zn. Biological community assessments were made microbial biomass (chloroform fumigation), soil basal respiration and dehydrogenase activity. During the 84-day period of the experiment, addition of Zn at both 500 and 1,000 mg kg(-1) had little detectable effect on soil pH. The concentration of NH4OAc-extractable Zn decreased rapidly within the initial six weeks. The concentration of HOAc-extractable Zn showed no decrease during 84 days incubation. EDTA-extractable Zn was greater than NH4OAc- and HOAc-extractable fractions, and showed a similar trend to NH4OAc-extractable after incubation. Microbial biomass, soil basal respiration and dehydrogenase activity all decreased over time during 84 days incubation. Addition of Zn resulted in a significant increase in specific respiration (qCO2). Microbial biomass and dehydrogenase activity did not appear to be influenced by added Zn, probably due to the strong buffering capacity of the soil. The Zn extracted by EDTA, HOAc and NH4OAc showed close relationships with each other (p < 0.001). Zinc extracted by 0.05 M EDTA and NH4OAc were highly correlated with soil basal respiration and specific respiration rate (p < 0.01). The results suggest that NH4OAc-extractable Zn combined with soil specific respiration could be used as parameters for risk assessment.

Acetates↗
PubMed2003

Effects of sediment phosphorus release associated with the density current on water quality of a subtropical and deep reservoir in Taiwan.

It was found that the increase of sediment P release in the anoxic state associated with the density current initiated by the cold front in the winter was the cause of the deterioration of the water quality of the subtropical, noncalcareous and deep reservoir, Feitsui Reservoir, in recent years. A mathematical model including the analytical solutions of the transport of the density current combined with a simple 2-layered water quality model has been established, describing the hydrodynamics and the water quality variation of the reservoir well. The continued sediment release of P in the anoxic state (from October to March) is an important P source and should be carefully assessed and controlled to reduce the impact of the internal loading of P incorporated with the density current on the water quality in future years.

Environmental Monitoring↗
PubMed2002

Phytotoxicity of dredged sediment from urban canal as land application.

Phytotoxicity of dredged sediment from Hangzhou section of the Grand Canal as land application was evaluated by pakchoi (Brassica chinensis L.) germination tests and pot experiments. Germination rates of pakchoi in the dredged sediment and in sediment-applied soils were both significantly higher than that in the soil controls, while the germination rate between the sediment-applied soils was no significant difference. In pot experiments, plant height and biomass were increased by the dredged sediment application rate in the rate of lower than 540 t ha(-1), but decreased when the application rate was over this rate. Concentrations of Zn and Cu in pakchoi were linearly increased with the increasing of the application rate of the dredged sediment. Both plant height and biomass of pakchoi in sediment-treated red soil were higher than that in sediment-treated paddy soil, regardless the application rate. The results suggest that plant biomass of pakchoi may be used as an indicator of the phytotoxicity of the dredged sediment. It also showed that red soil is more suitable to accept the dredged sediment than paddy soil, and 270 t ha(-1) is a safe application rate both in red soil and paddy soil.

Biomass↗
PubMed2002

A fast automatic RBS/w channeling system for damage depth profiling.

A computer-aided data acquisition coupling with goniometer-control system dedicated for damage depth profile measurements is established. The channeling direction searching is performed along tilt and azimuth directions. The system includes a computer code to convert the measured spectra into damage depth profile. The analyzing time for each sample requires approximately 20-30 min. The damage depth profiles of the self-implanted (100) silicon samples are in reasonable agreement with the calculated results yielded by the SRIM Monte-Carlo simulation code.

Journal Article↗
PubMed2002

Leukopenia and thrombocytopenia in hemodialysis patients with hepatitis B or C virus infection and non-hemodialysis patients with hepatitis cirrhosis.

AIMS: To investigate the relation of leukopenia and thrombocytopenia in hemodialysis (HD) patients with hepatitis C virus (HCV) infection. MATERIALS AND METHODS: The study included 86 HD patients with hepatitis B surface antigen-negative and hepatitis C antibody-negative, 28 HD patients with hepatitis C antibody-positive, 22 HD patients with hepatitis B surface antigen-positive, 78 non-HD patients with hepatitis B-induced liver cirrhosis and 38 non-hemodialysis patients with hepatitis C-induced liver cirrhosis. The following parameters were checked: anti-HCV, hepatitis B surface antigen, hemoglobin, hematocrit, white blood cells, platelets, calcium, phosphate, iron, ferritin, albumin, globulin, aspartate transaminase (AST), alanine transaminase (ALT) and C-reactive protein. The history of blood transfusions, medications, erythropoietin doses and adequate dialysis (KTNV) for 6 consecutive months was also recorded from charts. RESULTS: The HD patients with positive serum anti-HCV and non-HD patients with hepatitis B- or C-induced liver cirrhosis had higher prevalences of leukopenia (39.3%, 43.6% and 50% vs. 15.1%; p < 0.001) and thrombocytopenia (67.9%, 89.7% and 81.6% vs. 34.9%: p < 0.001) than HD patients with serum anti-HCV(-)HbsAg(-). The WBC (4,432 +/- 1,394, 4,792 +/- 2,263 and 4,624 2,446 vs. 5,590 +/- 1,500/mm3; p < 0.001) and platelet counts (140 +/- 45, 80 +/- 50 and 89 +/- 65 vs. 186 +/- 62 x 10(3)/mm3; p < 0.001) of HD patients with positive serum anti-HCV and non-HD patients with hepatitis B- or C-induced cirrhosis were also lower than HD patients without anti-HCV antibody. The liver cirrhosis patients had more thrombocytopenia than the HD patients with anti-HCV(+). The WBC and platelet counts did not vary between HD patients with HbsAg(+) and HD patients with anti-HCV(-)HBsAg(-). The durations of HD, hepatitis and liver cirrhosis were not related to the leukopenia or thrombocytopenia (p > 0.05). CONCLUSIONS: HCV infection associated with leukopenia and/or thrombocytopenia in HD patients is as common as in non-HD patients with liver cirrhosis. This may be due to the direct effect of hemopoiesis rather than the hyperspleenism of liver cirrhosis patients. There is a need for further prospective investigation to ascertain the clinical significance of leukopenia and thrombocytopenia in HD patients with anti-HCV(+). The prevalence of leukopenia and thrombocytopenia was higher in HD patients with hepatitis C than in HD patients with hepatitis B and HD patient without hepatitis.

Adult↗
PubMed2001

Development and characterization of a series of soluble tetrameric and monomeric streptavidin muteins with differential biotin binding affinities.

The strong biotin-streptavidin interaction limits the application of streptavidin as a reversible affinity matrix for purification of biotinylated biomolecules. To address this concern, a series of single, double, and triple streptavidin muteins with different affinities to biotin were designed. The strategy involves mutating one to three strategically positioned residues (Ser-45, Thr-90, and Asp-128) that interact with biotin and other framework structure-maintaining residues of streptavidin. The muteins were produced in soluble forms via secretion from Bacillus subtilis. The impact of individual residues on the overall structure of streptavidin is reflected by the formation of monomeric streptavidin to different extents. Of the three targeted residues, Asp-128 has the most dramatic effect (Asp-128 > Thr-90 > Ser-45). Conversion of all three targeted residues to alanine results in a soluble biotin binding mutein that exists 100% in the monomeric state. Both wild-type and mutated (monomeric and tetrameric) streptavidin proteins were purified, and their kinetic parameters (on- and off-rates) were determined using a BIAcore biosensor with biotin-conjugated bovine serum albumin immobilized to the sensor chip. This series of muteins shows a wide spectrum of affinity toward biotin (K(d) from 10(-6) to 10(-11) m). Some of them have the potential to serve as reversible biotin binding agents.

Amino Acid Sequence↗
PubMed2001

Arylcyclopropanecarboxyl guanidines as novel, potent, and selective inhibitors of the sodium hydrogen exchanger isoform-1.

A novel series of arylcyclopropanecarboxyl guanidines was synthesized and evaluated for activity against the sodium hydrogen exchanger isoform-1 (NHE-1). In biological assays conducted in an AP1 cell line expressing the human NHE-1 isoform, the starting cyclopropane 3a (IC(50) = 3.5 microM) shows inhibitory activity comparable to cariporide (IC(50) = 3.4 microM). Structure-activity relationships are used to optimize the affinity of various acyl guanidines for NHE-1 by screening the effect of substituents at both aryl and cyclopropyl rings. It is demonstrated that introduction of appropriate hydrophobic groups at the phenyl ring and a gem-dimethyl group at the cyclopropane ring enhances the NHE-1 inhibitory activity by up to 3 orders of magnitude (compound 7f, IC(50) = 0.003 microM). In addition, the gem-dimethyl series of analogues seem to display improved oral bioavailability and longer plasma half-life in rats. Furthermore, the lead benzodihydrofuranyl analogue 1 (BMS-284640) shows over 380-fold increased NHE-1 inhibitory activity as well as improved selectivity for NHE-1 over NHE-2 compared to cariporide.

Administration, Oral↗
PubMed2001

Morphometric identification of luminal narrowing of myocardial capillaries after cardioplegic arrest.

BACKGROUND: Because there is no smooth muscle cell surrounding the capillary endothelial cells, the effect of coronary microcirculation at the capillary level following cardioplegic arrest and reperfusion would be much different from that of resistant arterioles. We therefore studied the effect of hypothermic blood cardioplegic arrest and subsequent reperfusion on the myocardial capillaries in cardiac operation patients. METHODS: Twenty-seven patients who underwent cardiac operations were included in this study. Three sequential biopsies (preischemia, ischemia, and reperfusion) were obtained from the right atrium. This study was restricted to blood vessels with a diameter of less than 8 microns. Ten randomly selected capillaries from each biopsy were measured for luminal surface area, endothelial cytoplasmic surface area, and total cross-sectional surface area of capillaries. RESULTS: From stereologic morphometric studies, the serial changes in total cross-sectional surface area were not statistically significant (p = 0.152). However, there was a significant swelling of endothelial cytoplasm following ischemia and reperfusion (p = 0.0007). Meanwhile, changes in luminal surface area of capillaries following ischemia and reperfusion were also remarkable (p = 0.0008). CONCLUSIONS: The most striking finding of this study was the progressive decrease in capillary lumen during ischemia and after reperfusion. The swelling of endothelial cells is a major determinant of luminal narrowing of capillaries in patients receiving cardioplegic arrest.

Adolescent↗
PubMed2001

Feasibility of using metals to remediate water containing TCE.

The feasibility of treating underground water contaminated by a chlorinated organic compound with bimetallics Fe/ Ni, Zn/Ni and Zn single metal was studied. Column tests to simulate a reactive permeable wall in a funnel-and-gate system were used. Research results indicated that bimetallic Fe0/Ni0 and Zn0/Ni0 all had a very strong degraded power to trichloroethylene (TCE) at concentration up to 25 mg/l under different flow rates (27 cm/day-20 m/day). Furthermore, the concentrations of TCE and various ions in the treated effluent were nearly lower than the values specified in related standards for drinking water in Taiwan. These results showed that this technique could be effectively and safely used as an underground water remediation process.

Environmental Pollution↗
PubMed2001

Complete nucleotide sequence and cell-line multiplication pattern of the attenuated variant CH2195LA of Japanese encephalitis virus.

Strain-specific determinant of Japanese encephalitis virus (JEV) can be different among each virulence phenotype. We reported previously that the attenuated variant CH2195LA compared with the non-attenuated variant CH2195SA had four amino acid differences in E protein (E-85, E-306, E-331, and E-387) (Wu, S.-C., Lian, W.-C., Hsu, L.-C., Liau, M., 1997. Japanese encephalitis virus antigenic variants with characteristic differences in neutralization resistance and mouse virulence. Virus Res. 51, 173-181). Our present study determined the complete nucleotide sequences of these two variants and found another five amino acid changes in the nonstructural gene regions, including NS2A-215, NS3-350, NS4B-196, NS4B-197, and NS4B-198. The complete nucleotide sequences of the attenuated variant CH2195LA were compared with the non-attenuated variant CH2195SA and other 13 JEV strains. CH2195LA was mostly close to CH2195SA and JaOArS982, and phylogenetically distant to SA14-14-2, SA14-2-8, and RP-2ms of the attenuated JEV strains. The multiplication patterns for CH2195LA compared with CH2195SA in other seven cell lines were different from Vero cells. Relative fitness vector analysis based on a mixture of both variants during cell passage indicated the attenuated variant CH2195LA showed increased viral fitness in Vero cell adaptation. These results revealed that the attenuated variant CH2195LA was unique to culture in Vero cells.

Amino Acid Substitution↗