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Biomedical subjects

Wei Sun

Publications and source records attributed to Wei Sun.

At least 91 records · Page 5Linked to original sources
PubMed2005

Removal of earthy-musty odorants in drinking water by powdered activated carbon.

The removal of four earthy-musty compounds, 2-methylisoborneol (MIB), 2,4,6-trichloroanisole (TCA), 2-isopropyl-3-methoxy-pyrazine (IPMP), and 2-isobutyl-3-methoxy-pyrazine (IBMP), by powdered activated carbon (PAC) were investigated under the simulative condition of Xicun water plant, Guangzhou. The adsorption kinetics of odor compounds by two PACs show that main removal of odor compounds occurs within contact time of 1 h. Compared with the wood-based PAC, the coat-based PAC evidently improves the removal efficiency of poorly adsorbed compounds like MIB. The effects on removal efficiency such as optimum PAC dosage, initial concentration of the organics, chlorine residual, background organics, and changes of water quality were investigated. The percent removal of trace odorants at any given time for a particular carbon dosage is irrelative to the initial concentration of the odor compounds. Adsorptive capacity of PAC for target compounds is reduced by chlorine residual and background organics. Characteristics of raw water have vast influence on the removal of target compounds by PAC.

Adsorption↗
PubMed2005

Chemokine RANTES is upregulated in monocytes from patients with hyperhomocysteinemia.

AIM: To investigate the changes in plasma level of the chemokine RANTES (regulated upon activation, normal T cells expressed and secreted) and the responsiveness of lipopolysaccharide (LPS)-induced RANTES secretion from monocytes in patients with hyperhomocysteinemia (HHcy). METHODS: The plasma levels of homocysteine (Hcy), folate, and RANTES were measured in 38 control patients with normal Hcy levels and 40 patients with HHcy and the mRNA synthesis of RANTES in isolated human monocytes was determined by RNase protection assays. RESULTS: The plasma level of RANTES was elevated in HHcy patients compared with controls (median 5.3 vs 3.5 ng/mL, P<0.01). LPS-induced RANTES production from monocytes of HHcy patients was also increased significantly. In addition, Hcy directly increased the mRNA level of RANTES in isolated normal human monocytes in a time- and dose-dependent manner. CONCLUSION: Upregulated RANTES from monocytes in HHcy patients may be involved in the atherogenesis of HHcy-induced atherosclerosis.

Adult↗
PubMed2005

Effects of boundary conditions on the estimation of the planar biaxial mechanical properties of soft tissues.

Evaluation and simulation of the multiaxial mechanical behavior of native and engineered soft tissues is becoming more prevalent. In spite of this growing use, testing methods have not been standardized and methodologies vary widely. The strong influence of boundary conditions were recently underscored by Waldman et al. [2002, J. Materials Science: Materials in Medicine 13, pp. 933-938] wherein substantially different experimental results were obtained using different sample gripping methods on the same specimens. As it is not possible to experimentally evaluate the effects of different biaxial test boundary conditions on specimen internal stress distributions, we conducted numerical simulations to explore these effects. A nonlinear Fung-elastic constitutive model (Sun et al., 2003, JBME 125, pp. 372-380, which fully incorporated the effects of in-plane shear, was used to simulate soft tissue mechanical behavior. Effects of boundary conditions, including varying the number of suture attachments, different gripping methods, specimen shapes, and material axes orientations were examined. Results demonstrated strong boundary effects with the clamped methods, while suture attachment methods demonstrated minimal boundary effects. Suture-based methods appeared to be best suited for biaxial mechanical tests of biological materials. Moreover, the simulations demonstrated that Saint-Venant's effects depended significantly on the material axes orientation. While not exhaustive, these comprehensive simulations provide experimentalists with additional insight into the stress-strain fields associated with different biaxial testing boundary conditions, and may be used as a rational basis for the design of biaxial testing experiments.

Animals↗
PubMed2005

Simulated bioprosthetic heart valve deformation under quasi-static loading.

For more than 40 years, the replacement of diseased natural heart valves with prosthetic devices has dramatically extended the quality and length of the lives of millions of patients worldwide. However, bioprosthetic heart valves (BHV) continue to fail due to structural failure resulting from poor tissue durability and faulty design. Clearly, an in-depth understanding of the biomechanical behavior of BHV at both the tissue and functional prosthesis levels is essential to improving BHV design and to reduce rates of failure. In this study, we simulated quasi-static BHV leaflet deformation under 40, 80, and 120 mm Hg quasi-static transvalvular pressures. A Fung-elastic material model was used that incorporated material parameters and axes derived from actual leaflet biaxial tests and measured leaflet collagen fiber structure. Rigorous experimental validation of predicted leaflet strain field was used to validate the model results. An overall maximum discrepancy of 2.36% strain between the finite element (FE) results and experiment measurements was obtained, indicating good agreement between computed and measured major principal strains. Parametric studies utilizing the material parameter set from one leaflet for all three leaflets resulted in substantial variations in leaflet stress and strain distributions. This result suggests that utilization of actual leaflet material properties is essential for accurate BHV FE simulations. The present study also underscores the need for rigorous experimentation and accurate constitutive models in simulating BHV function and design.

Animals↗
PubMed2005

Origin differentiation of heroin sample and its acetylating agent with (13)C isotope ratio mass spectrometry.

A novel method for deducing the origins of heroin and the reagent used for acetylation was established based on delta(13)C determinations of heroin and its hydrolysate, morphine, using gas chromatography (13)C isotope ratio mass spectrometry (GC-C-IRMS). The alkaline and acid hydrolysis conditions of heroin were optimized. Both yield and purity of morphine produced could meet the requirement for a GC-C-IRMS analysis. Using (2-diethylaminoethyl-2,2- diphenylvalerate) as internal standard the determinations of heroin and morphine contents were performed with a GC method in a linear range of 0.2 to 2.0 mg ml(1) that was required to gain the isotope ratio results. The hydrolysis and synthesis of heroin did not change the delta(13)C value of morphine. The precision for delta(13)C detection of both heroin and morphine was sufficient for origin differentiation of heroin samples. The information about the origins of acetylation reagents could be deduced from the difference of delta(13)C values between heroin and morphine. The results for origin differentiation of 10 heroin samples grouped into different regions and their acetylating agents were satisfactory.

Acetylation↗
PubMed2005

An analysis of protein abundance suppression in data dependent liquid chromatography and tandem mass spectrometry with tryptic peptide mixtures of five known proteins.

Reverse phase liquid chromatography (RPLC) has been widely used in proteomics research for peptide separation. When protein samples are separated by RPLC and identified with electrospray ion trap mass spectrometry (ESI-MS), the signals of high-abundance proteins may suppress those of low-abundance proteins, a phenomenon known as abundance suppression. To what degree the abundance suppression correlates to the number of tryptic peptides in the high-abundance proteins has not been carefully investigated. We tried to answer this question by studying the mixtures digested from five known proteins. The numbers of identified tryptic peptides (longer than five amino acids) of the five proteins ranged from 12 to 47. Four different peptide mixtures with 10- to 100-fold abundance differences of five known proteins were separated by RPLC and identified by ESI-MS. Our results showed that abundance suppression was related to the tryptic peptide numbers in the high-abundance protein. Within a 100-fold protein abundance difference range, tryptic peptide number in the low-abundance proteins could be suppressed up to seven times by high-abundance proteins. The procedure we suggest here can help to identify low-abundance proteins co-purified with their high-abundance binding protein. The result can also help to identify specific high-abundance proteins for removal by immunoaffinity.

Animals↗
PubMed2005

Voltage-sensitive and ligand-gated channels in differentiating neural stem-like cells derived from the nonhematopoietic fraction of human umbilical cord blood.

Fetal cells with the characteristics of neural stem cells (NSCs) can be derived from the nonhematopoietic fraction of human umbilical cord blood (HUCB), expanded as a nonimmortalized cell line (HUCB-NSC), and further differentiated into neuron-like cells (HUCB-NSCD); however, the functional and neuronal properties of these cells are poorly understood. To address this issue, we used whole-cell patch-clamp recordings, gene microarrays, and immunocytochemistry to identify voltage-gated channels and ligand-gated receptors on HUCB-NSCs and HUCB-NSCDs. Gene microarray analysis identified genes for voltage-dependent potassium and sodium channels and the neurotransmitter receptors acetylcholine (ACh), gamma-aminobutyric acid (GABA), glutamate, glycine, 5-hydroxytryptamine (5-HT), and dopamine (DA). Several of these genes (GABA-A, glycine and glutamate receptors, voltage-gated potassium channels, and voltage-gated sodium type XII alpha channels) were not expressed in the HUCB mono-nuclear fraction (HUCB-MC), which served as a starting cell population for HUCB-NSC. HUCB-NSCD acquired neuronal phenotypes and displayed an inward rectifying potassium current (Kir) and an outward rectifying potassium current (I(K+)). Kir was present on most HUCB-NSCs and HUCB-NSCDs, whereas I(K+) was present only on HUCB-NSCDs. Many HUCB-NSCDs were immunopositive for glutamate, glycine, nicotinic ACh, DA, 5-HT, and GABA receptors. Kainic acid (KA), a non-N-methyl-D-asparate (NMDA) glutamate-receptor agonist, induced an inward current in some HUCB-NSCDs. KA, glycine, DA, ACh, GABA, and 5-HT partially blocked Kir through their respective receptors. These results suggest that HUCB-NSCs differentiate toward neuron-like cells, with functional voltage- and ligand-gated channels identified in other neuronal systems.

Antigens, CD34↗
PubMed2005

Aspirin at low-intermediate concentrations protects retinal vessels in experimental diabetic retinopathy through non-platelet-mediated effects.

The prevention of diabetic retinopathy requires drugs that leverage the benefits of glycemic control without adding the burden of side effects. Aspirin at dosages of 1-1.5 g/day has prevented manifestations of diabetic retinal microangiopathy in a clinical trial as well as in studies with dogs. Because lower and safer doses of aspirin could be used if its beneficial effects on retinopathy were due to antithrombotic effects, we compared the effects of a selective antiplatelet drug (clopidogrel) to those of aspirin in streptozotocin-induced diabetic rats. Clopidogrel did not prevent neuronal apoptosis, glial reactivity, capillary cell apoptosis, or acellular capillaries in the retina of diabetic rats. Aspirin, at doses yielding serum levels (<0.6 mmol/l) well below the anti-inflammatory range for humans, prevented apoptosis of capillary cells and the development of acellular capillaries but did not prevent neuroglial abnormalities. The aldose reductase inhibitor sorbinil, used as the benchmark for the effect of the other drugs, prevented all abnormalities. The diabetic rat retina showed increased expression of the transcription factor CCAAT/enhancer-binding protein-beta, one of the known targets of low-intermediate concentrations of aspirin. Thus we found a spectrum of drug efficacy on the prevention of experimental diabetic retinopathy, ranging from the absent effect of a selective antiplatelet drug to the prevention of all abnormalities by an aldose reductase inhibitor. Aspirin at low-intermediate concentrations selectively prevented microangiopathy. The minimal effective dose of aspirin should now be sought.

Animals↗
PubMed2005

[Hearing screening in infants with congenital cytomegalovirus infection].

OBJECTIVE: To investigate the impact of congenital cytomegalovirus infection on the hearing ability in infants. METHODS: By using the tools of distortion product otoacoustic emission (DPOAE) and auditory brain-stem response (ABR), the hearing ability of 38 infants with congenital cytomegalovirus infection and 16 cases of normal controls during neonatal periods was screened with a follow-up study at 6 and 24 months. RESULT: In infants with congenital cytomegalovirus infection, 86.8% (66/76) ears at neonatal stage and 76.3% (58/76) ears at 6 months passed the tests; while in normal controls, 96.9% (31/32) ears passed the tests. The reaction threshold of ABR V in infants with congenital cytomegalovirus infection was higher than that in normal controls (P<0.005). Furthermore,in infants with congenital cytomegalovirus infection, 13 ears (17.1%) were extreme hearing loss, 5 ears (6.6%) were severe hearing loss, and 6 ears (7.9%) were moderately severe hearing loss. The incidence of hearing loss during the follow-up was 7.9% (3/38) at neonatal stage, 23.7% (9/38) at 3-4 months, and 7.9% (3/38) after 6 months. CONCLUSION: The congenital cytomegalovirus infection could cause the prompt and late-onset hearing loss. The combination of the laboratory evidence with the dynamic hearing screening may contribute to the early detection of hearing loss in infants with congenital cytomegalovirus infection.

China↗
PubMed2005

Overexpression of osteopontin in rheumatoid synovial mononuclear cells is associated with joint inflammation, not with genetic polymorphism.

OBJECTIVE: Osteopontin (OPN) is thought to play an important role in rheumatoid synovitis. We investigated the expression of OPN in rheumatoid synovial fluid mononuclear cells (SFMC) and its potential association with genetic polymorphism of the OPN gene and joint inflammation in rheumatoid arthritis (RA). METHODS: 1. The expression of OPN mRNA in peripheral blood mononuclear cells (PBMC) and SFMC of patients with RA was analyzed quantitatively by real-time polymerase chain reaction (PCR). Results were analyzed in paired PBMC and SFMC and control PBMC. 2. Six single nuclear acid polymorphisms of the OPN gene were genotyped in a cohort of 192 Chinese patients with RA and controls (n = 288) by restriction fragment length polymorphism PCR or direct DNA sequencing. 3. SF derived from RA patients was examined for the stimulating effect on mRNA expression of the OPN gene in PBMC. RESULTS: The expression of OPN gene was significantly increased in SFMC and, to a lesser degree, in PBMC of patients with RA compared to control PBMC (p < 0.01). However, the prevalence of OPN genotype and allele frequencies at the selected positions did not differ significantly between RA patients and the control group (p > 0.05). Further characterization indicated that SF known to contain a variety of proinflammatory factors significantly stimulated mRNA expression of OPN in PBMC obtained from RA patients or healthy controls. CONCLUSION: Overexpression of OPN mRNA in SFMC is associated with proinflammatory factors produced in inflamed joints, but not with OPN genetic polymorphisms. OPN gene polymorphisms do not correlate with susceptibility to RA.

Adult↗
PubMed2005

[Suppressive effects of GTW treatment on mesangial lesions in experimental irreversible glomerulosclerosis].

OBJECTIVE: To examine suppressive effects of multi-glycoside of Tripterygium wilfordii Hook. f. (GTW)on mesangial injury induced by two-injecti on of anti-Thy1. 1 monoclonal antibody(mAb) 1-22-3 in vitro. METHOD: We established the irreversible model of glomerulosclerosis with anti-Thy1. 1 mAb 1-22-3. After 42 days of oral treatment with GTW (50 mg x kg(-1) BW)and vehicle (distilled water), to observe effects of GTW on proteinuria, renal function, mesangial morphological change, and mRNA expressions of collagen type I and TGF-beta by light microscope (LM), immunofluorescence (IF), and Reverse Transcription Polymerase Chain Reaction (RT-PCR). RESULT: GTW ameliorated proteinuria (from day24 to day 42) and mesangial proliferation [total cell number, GTW group 65.67+/-3.43 vs. control group 87.02+/-2.41, P < 0.05; matrix expansion, GTW group 1.20+/-0.06 vs. control group 2.77+/-0.23, P < 0.05; alpha-smooth muscle actin(alpha-SMA) expression, GTW group 1.75+/-0.33 vs. control group 2.62+/-0.15, P < 0.05; collagen type I expression, GTW group 1.68+/-0.31 vs. control group 2.06+/-0.24, P < 0.05], moreover, significantly reduced the glomerular expression of mRNA for collagen type 1(53.5% to the control group, P < 0.05)and TGF-beta(14.7% to the control group, P < 0.05)on day 42day. CONCLUSION: GTW can not only decrease proteinuria, but also ameliorate mesangial alterations probably by the reduction of cytokines. GTW may be a promising agent for the prevention of progressive and irreversible glomerulosclerosis.

Actinin↗
PubMed2005

Neurogenic pulmonary edema in head injuries: analysis of 5 cases.

OBJECTIVE: To review the pathophysiology and study the diagnosis and clinical management of neurogenic pulmonary edema (NPE). METHODS: The data of 5 patients who developed NPE after head injury treated in our hospital form December 1995 to May 2003 were collected and analyzed. RESULTS: The patients developed dyspnea and respiratory failure 2-8 hours after neurologic event. Four of the 5 patients presented with pink frothy sputum. Chest radiography showed bilateral diffuse infiltrations in all the 5 patients. After supportive measures such as oxygen support and pharmacologic therapy, 4 patients recovered in 72 hours and one patient died. CONCLUSIONS: The pathophysiologic mechanisms of NPE is unclear. In acute respiratory failure following head injury, NPE must be given much attention and timely and effective measures should be taken.

Adolescent↗
PubMed2005

[Study on antioxidant activity of essential oils and its monomer from Pelargonium graveolens].

The antioxidant effects of essential oil and monomer as well as residue and waste water after distillation from buds, stems and leaves of Pelargonium graveolens were studied by the method of 1,1-diphenyl-2-picryl hydrazyl free redical (DPPH*). It showed that each sample in the test had the antioxidant effect. The extraction of the leaf collected in noon had the strongest antioxidant effect, the residue and waste water had also strong antioxidant effect. It shows that some antioxidant chemical abounds in the residue of natural essential industry, and it also shows feasibility of integrated use of Pelargonium graveolens.

Antioxidants↗
PubMed2005

[Bayesian regularized BP neural network model for quantitative relationship between the electrochemical reduction potential and molecular structures of chlorinated aromatic compounds].

Bayesian regularized BP neural network (BRBPNN) technique was applied in QSPR model in environmental field. The BRBPNN model for quantitative relationship between the electrochemical reduction potential (ERP) and chemical structures of 87 chlorinated aromatic compounds was established. The structure descriptor pool is consisted of Cl number (Cl), molecular weight (MW) and 6 quantum chemistry parameters which are calculated by MOPAC2000 built in ChemOffice2004, including energy of the highest occupied molecular orbital (E(HOMO)), energy of the lowest occupied molecular orbital (E(LUMO)), heat of formation(HF), dipole(DIP), electronic energy(EE), core-core repulsion(CCR). The achieved optimal network structure was 6-20-1, which possessed stronger fitting and prediction capacity than that of the stepwise linear regression and with the correlation coefficients square and the mean square error for the training set and the test set as 0.999 and 0.000105, 0.965 and 0.00159 respectively. The sum of square weights between each input neuron and the hidden layer of BRBPNN(6-20-1) indicate the effect of descriptor on the electric potential declining in the order of ELUMO > EHOMO > HF> CCR > EE > DIP. The scatter diagrams show that the EE descriptors had positive effect on ERP, and ELUMO, HF, DIP had negative effects, and EHOMO and CCR showed ambiguous effects. Results show that Bayesian regularized BP neural network is of automated regularization parameter selection capability and thus may ensure the excellent generation ability and robustness. This study threw more light on the applicability of electrochemical treatment for the chlorinated aromatic compounds and the analysis on electrochemical reduction mechanism.

Bayes Theorem↗
PubMed2005

[Experimental study on viscoelastic properties of human cornea].

The biomechanical properties of eight human corneas from four normal Chinese fresh corpses were investigated by use of one dimension tensile test, tensile stress relaxation and creep test. The destructive load, stretchy ratio, spreading stress, spreading strain and elastic modulus were determined. Also obtained were the stress relaxation and creep data and curves. After reduction of data, the reduced stress relaxation and creep data and curves were worked out. The regression method was used to get the regression coefficient. The least square method was employed to fit the data of stress and strain; then the stress-strain formula was expressed and the curves of human cornea were plotted. The constitutive equation is K (lambda,t) = G(t) T(e) (lambda) and some conclusions are drawn.

Biomechanical Phenomena↗
PubMed2005

Evaluation of sequest result filter-Xcorr and Unified Score.

OBJECTIVE: To estimate the effect of two simple filters, two or more positive peptide filter and Unified Score filter on the true positive rate of protein and peptide. METHODS: Twenty-two LC-MS/MS datasets were from 18 known protein mixture. Two or more positive peptide filter and Unified Score filter were applied to the 22 datasets. The filters effect was evaluated according to the true positive rate of protein and peptide for each filter. RESULTS: The positive rates of protein and peptide from two or more peptide filter raised from 56.49% to 92.86%-99.12% (for protein) and from 90.67% to 97.74%-99.62% (for peptide), but many positive proteins were filtered out. The positive rates of protein and peptide from Unified Score (ThermoFinnigan value 2400) were only about 35.51% and 82.99%, but after adjusted the value (3900) according to the number of false positive peptide, those positive rate raised to 63.61% (for protein) and 91.97% (for peptide). CONCLUSIONS: Two or more peptides requirement could significantly decrease false positive rate, but it also may filter out many true positive proteins especially low molecular weight and less abundant proteins. Unified Score may be a better filter than Xcorr and DeltaCn combination and the value of 3900 is found to be more suitable for this particular datasets.

Algorithms↗
PubMed2005

[K-mean cluster analysis for incisal jaw morphology of normal occlusion subjects among different vertical facial skeletal types].

OBJECTIVE: To study the incisal jaw morphology of subjects with normal occlusion and to discuss the relationship between different vertical facial skeletal types and different incisal jaw cluster types. METHODS: After studied by radiographic cephalometry, the incisal jaw morphology of 169 subjects with normal occlusion in early permanent dentition were analyzed by K-mean cluster analysis. RESULTS: Morphology of maxillary or mandibular incisal jaws could be divided into four types separately, including division I, division II, division III and division N. In maxilla or in mandible, the incisal jaw morphology of division I was characterized by wideness and shortness. In contrast, division II was characterized by thinness and length. As for division III and division IV, both of two were intermediate types between division I and division II . In maxilla, it was found that division II was the majority (86.49%) in the high-angle subjects, division III was the majority (47.67%) in the average-angle subjects, and division I and III were the majority (82.61%) in the low-angle subjects. In mandible, it was found that division II was the majority (51.35%) in the high-angle subjects, division IV was the majority (48.84%) in the average-angle subjects, and division III and IV were the majority (69.57%) in the low-angle subjects. CONCLUSION: Owing to the obvious characteristics of morphology in each cluster types and in each vertical facial skeletal types, different clinic considerations must be put forward when we want to move the incisor.

Cephalometry↗