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Biomedical subjects

Chun Wang

Publications and source records attributed to Chun Wang.

At least 37 records · Page 2Linked to original sources
PubMed2006

[Simultaneous determination of levodopa and methyldopa in human serum by capillary electrophoresis].

A simple capillary electrophoresis method was developed for the determination of levodopa and methyldopa in human serum. The effects of pH and concentration of buffer, voltage and injection time on separation were investigated. As a result, an optimized separation was obtained with a fused-silica capillary of 60.2 cm (50 cm effective length) x 75 microm i. d. in a running buffer of 40 mmol/L sodium tetraborate (pH 9.5) with an applied voltage of 22 kV at 25 degrees C. Sample introduction was performed at 3.45 kPa (0.5 psi) for 7 s and on-column detection was made with a diode array detector at 200 nm. The linear responses covered the ranges from 1.0 to 64.0 mg/L (r = 0.999 8) for methyldopa and from 1.0 to 71.0 mg/L (r = 0.999 4) for levodopa. The detection limits (S/N = 3) of methyldopa and levodopa were shown to be 0.6 mg/L and 0.8 mg/L, respectively. The recoveries for levodopa and methyldopa in human serum were between 82.8% and 88.8% with relative standard deviations between 2.10% and 2.63%.

English Abstract↗
PubMed2006

[Interaction of quercetin and bovine serum albumin].

The interaction of quercetin and bovine serum albumin (BSA) was investigated using fluorescence spectroscopy (FS) and ultraviolet spectroscopy (UV). The apparent binding constants (KA) between quercetin and BSA were 2.8 x 10(8) (26 degrees C) and 3.1 x 10(8) (36 degrees C), and the binding sites (n) were 1.7+/-0.02. According to the Förster theory of non-radiation energy transfer, the binding distances (r) were also obtained. The experimental results showed that the quercetin could be inserted into the BSA, quenching the inner fluorescence by forming the quercetin-BSA complex. It was found that both static quenching and non-radiation energy transfer were the main reasons for the fluorescence quenching. The process of binding was a spontaneous molecular interactioln in which entropy increased while Gibbs free energy decreased, indicating that the interaction of quercetin and BSA was driven mainly by hydrophobic force.

Algorithms↗
PubMed2006

[Developments of liquid-phase microextraction based on hollow fiber].

The liquid-phase microextraction (LPME), based on disposable hollow fiber, has been developed to be a new environmentally benign sample preparation technique which incorporate sampling, extraction and concentration into a single step. The novel technique can be easily manipulated in combination with high performance liquid chromatography, gas chromatography and capillary electrophoresis, and can provide excellent sample clean-up effect and high degree of extraction recovery and enrichment. It is proved to be simple, low-cost and virtually solvent-free. The extraction set-up, extraction mode, basic principles and recent applications of the hollow fiber-based liquid-phase microextraction are reviewed.

Analytic Sample Preparation Methods↗
PubMed2006

[Drug resistance reversal of HL-60/ADR cells by simultaneous suppression of XIAP and MRP].

This study was purposed to explore the mechanisms of drug resistance of HL-60/ADR cells and to compare the reversal drug-resistance effects of antisense oligonucleotides (AS ODN) of XIAP (X-linked inhibitor of apoptosis protein) and AS ODNs of MRP (multidrug resistance-associated protein) by use alone or in combination. Reverse transcription-PCR and Western blot were applied to detect the expression of XIAP, BCL-2, MRP and MDR1 in mRNA and protein levels of HL-60 cells and HL-60/ADR cells, respectively. Fully phosphorothioated AS ODN of XIAP and MRP was delivered into HL-60/ADR cells with Lipofectamine 2000 in the form of liposome-ODN complexes alone or in combination. CCK-8 cell viability assay was used to determine the effect of AS ODN of XIAP and MRP used alone or in combination on the chemotherapy sensitivity of HL-60/ADR cells to daunorubicin (DNR). Reverse transcription-PCR and Western blot were applied to examine the changes of XIAP, MRP in mRNA and protein levels respectively. The results showed that MRP and XIAP were both significantly higher in HL-60/ADR cells than those in HL-60 cells. AS ODN of XIAP and MRP down-regulated the expression of XIAP and MRP in HL-60/ADR cells and increased the sensitivity of HL-60/ADR cells to DNR, respectively. AS ODN of XIAP + MRP did not enhance the inhibition expression of XIAP in HL-60/ADR cells but increased the sensitivity of HL-60/ADR cells to DNR significantly as compared with AS ODN of XIAP (P < 0.05). AS ODN of XIAP + MRP did not increase the concentration of DNR nor enhanced the inhibition expression of MRP in HL-60/ADR cells but increased the sensitivity of HL-60/ADR cells to DNR significantly (P < 0.05), as compared with AS ODN of MRP. It is concluded that both XIAP and MRP may be involved in the drug resistance mechanisms of HL-60/ADR cells. Drug-resistance of HL-60/ADR cells can be reversed significantly when antisense oligonucleotides of XIAP and MRP were used in combination.

Doxorubicin↗
PubMed2005

Micropatterning of polystyrene nanoparticles and its bioapplications.

Micropatterning of biomolecules forms the basis of cell culture, biosensor and microarray technology. Currently, the most widely used techniques are photoresist lithography, soft lithography or using robots which all involve multi-step surface modification directly on a planar substrate. Here we report a method to pattern biomolecules through self-assembling polystyrene nanoparticles in arrayed microwells on a solid surface to form well-ordered patterning, followed by attaching biomolecules to the assembled nanoparticles. The formation of colloidal patterns depends on capillary force, surface wettability and physical confinement. This method can be used for micropatterning a variety of biomolecules such as protein and antibody.

Colloids↗
PubMed2005

Nanoparticle-assisted micropatterning of active proteins on solid substrate.

Micropatterning of proteins on silica substrate was achieved using a new method. Proteins were first immobilized onto silica nanoparticles which were then dispensed into arrayed microwells on silicon. Atomic force microscopy (AFM), fluorescence microscopy and Fourier transform infrared (FTIR) spectroscopy were used to characterize the samples. The results showed that, compared to a planar surface, curved surfaces of nanoparticles provide more space for attaching proteins and thus increases the intensity of fluorescence signal. Furthermore, after attaching to silica nanoparticles, bovine serum albumin (BSA) maintains its major structure and the cytokine IFN-gamma maintains its ability to bind to its antibody. Use of this method can be extended to micropatterning of other biomolecules, such as DNA and enzymes.

Adsorption↗
PubMed2005

The effect of perceived spatial separation on informational masking of Chinese speech.

The effect of perceived spatial separation, induced by the precedence effect, on release from noise or speech masking was investigated. Listeners were asked to orally repeat Chinese nonsense sentences, which were spoken by a female talker and presented by both the left (-45 degrees) and right (+45 degrees) loudspeakers, when maskers, which were either speech-spectrum noise sounds or Chinese nonsense sentences spoken by two other female talkers, were presented by the same two loudspeakers. Delays between identical sounds presented over the two loudspeakers were used to control the perceived locations of the target (right only) and masker (right, center, or left). The results show that perceived 45 degrees and 90 degrees separations of target speech from masking speech led to equivalently marked improvement in speech recognition, even though the degree of improvement was smaller than that reported in [J. Acoust. Soc. Am. 106 (1999) 3578 (using English nonsense speech)]. When the masker was noise, however, perceived separation only marginally improved speech recognition. These results indicate that release from informational masking, due to perceived target/masker spatial separation induced by the precedence effect, also occurs for tonal Chinese speech. Compared to the 45 degrees perceived within-hemifield separation, the 90 degrees perceived cross-hemifield separation does not produce further unmasking.

Acoustic Stimulation↗
PubMed2005

[Effects of volatile organic compounds inhalation on the inflammation biomarkers in nasal lavage fluids of decoration workers].

OBJECTIVE: To study the effects of volatile organic compounds (VOCs) inhalation on the inflammation biomarkers in nasal lavage fluid (NAL), and to assess the practicability of the nasal lavage methods. METHODS: 32 volunteers joined in this study, among whom 20 Painters were chosen as exposed group, and 12 plumbers and electricians were chosen as controls. Lung function was detected, and several inflammation biomarkers (IL-4, IL-5, ECP) in nasal lavage (NAL) were determined. RESULTS: The average FEV1 of exposed group was 3.08L, which was significantly lower than the control. And the concentration levels of inflammation biomarkers in NAL of painters were higher than that of the control. Among these detected biomarkers, the ECP level was significantly higher in exposed group than in control group(the mean was 3.57 microg/L in painter and 2.79 microg/L in the control, respectively). Moreover, there was statistically negative correlation between ECP level and FEV1 (a kind of lung function parameters), the correlated coefficient was -0.381. CONCLUSION: Inhalation of VOCs could be responsible for the occurrence of respiratory inflammation and allergic illness such as rhinitis and asthma. Moreover, the method of nasal lavage is practicable for population study.

Adult↗
PubMed2005

[Relationship between peripheral insulin resistance and beta-cell function in obese subjects].

OBJECTIVE: To detect the relationship between peripheral insulin resistance and beta-cell function in obese subjects with normal blood glucose, and to explore the role of free fatty acids (FFAs) in the pathogenesis of type 2 DM. METHODS: Ten simple obesity male subjects (OB) with normal blood glucose and 10 lean male persons (NC) matched on age and living style were included. None of them was smoker, and their blood pressure, serum cholesterol levels were all normal. All subjects underwent the following tests: (1) Fasting serum lipids profile and FFA; (2) Baseline immunoreactive insulin (IRI), pro-insulin (PI) and true-insulin (TI); (3) Acute insulin response (AIR) to an intravenous bonus of glucose; (4) Euglycemic hyperinsulinemia clamp study to assess the peripheral glucose disposal rate (GDR). RESULTS: In obesity subjects, the baseline IRI, PI and TI were elevated and the ratio of PI/(PI + TI) was higher than controls (P < 0.01). The AIR was enhanced in OB and the area under the curve was larger (P < 0.05), but in obesity subjects the plasma glucose levels at 3, 5 and 10 minutes were much higher than controls (P < 0.05). The GDRs obtained during steady state were markedly decreased in OB (P < 0.05). The serum lipids profiles were normal except that triglyceride was higher in OB (P < 0.05) and the FFAs concentration was also elevated in OB (P < 0.05). There was a negative correlation between FFAs concentration and GDR in OB groups (r = -0.767, P < 0.01). CONCLUSION: The present data showed that in obese subjects with normal blood glucose, there were severe peripheral insulin resistance, relative deficiency of beta-cell first-phase insulin release and increased ratio of pro-insulin to insulin. It is logical to deduce that both insulin resistance and the beta-cell changes could be, at least partially, secondary to high levels of serum FFAs. Elevated circulating FFAs may paly a role in the pathogenesis of type 2 DM.

Adult↗
PubMed2005

[A case of Gitelman's syndrome presenting with severe hypocalcaemia and hypokalemic periodic paralysis].

HISTORY AND CLINICAL FINDINGS: A 63-year-old woman was admitted with fatigue, general malaise, paraesthesiae, muscle cramping and weakness of the limbs. Since the age of 13, she had suffered from a transient lower extremities paralysis 3 times. Past history was unremarkable. There was no family history of disease. In addition, she denied any form of self-medication, surreptitious diuretic and laxative abuse, persistent vomiting and diarrhea. The blood pressure was 120/70 mmHg, BMI = 23.0 kg/m2, WHR = 0.84. A little anxious. The results of physical examinations were unnoticeable. The cranial-nerve functions were intact. Manual muscle tests revealed her extremities in normal condition. Sensation was normal in all modalities. The deep tendon reflexes were present but decreased mildly. INVESTIGATIONS: Laboratory tests showed moderate to severe hypokalemia with a serum potassium concentration of 2.77 to 3.17 mmol/L, hypomagnesemia (0.31-0.35 mmol/L), hypocalcaemia (1.79-1.99 mmol/L), hypocalciuria (0.12-1.10 mmol/24 h), and metabolic alkalosis. The patient had elevated plasma renin activity and normoaldosteronism; her parathyroid hormone level was normal. Urinary calcium to creatinine ratio was (5.17-23.57) x 10(-3) mg/mg Cr. The renal clearance studies in this patient using furosemide or hydrochlorothiazide disclosed that urine volume and chloride clearance (CCL) were increased after furosemide administration, but there was no obvious change after the administration of hydrochlorothiazide. Furthermore, the distal fractional chloride reabsorption [CH2O/(CH2O+CCI)] was dramatically decreased by furosemide administration, whereas thiazide had little effect on it. These findings pointed to the presence of a non-functional thiazide-sensitive sodium/chloride cotransporter in the distal convoluted tubule, so the diagnosis of Gitelman's syndrome (GS) was made. TREATMENT: The patient was treated with indomethacin 50 mg, tid; after 3 days, the potassium increased, but calcium and magnesium serum levels failed to improve. So triamterene 50 mg, tid was also administrated. After 4 days, the serum levels of potassium, calcium were normalized, and the serum levels of magnesium increased from 0.35 mmol/L to 0.52 mmol/L; weakness and fatigue improved markedly, the clinical symptoms disappeared. The 18-month-follow-up study found the magnesium serum level normal. CONCLUSION: GS may be present with severe hypocalcaemia and hypokalemic periodic paralysis; the renal clearance studies by diuretic administration may be of help in diagnosing Gitelman's syndrome, and the combined use of indomethacin with triamterene has good therapeutic effect.

Alkalosis↗
PubMed2005

[Study on the relationship between polymorphisms of peroxisome proliferators-activated receptor-gamma coactivator-1alpha gene and type 2 diabetes in Shanghai Hans in China].

OBJECTIVE: To observe the association between single nucleotide polymorphism (SNP) of peroxisome proliferators-activated receptor-gamma coactivator-1alpha (PGC-1alpha ) gene and type 2 diabetes mellitus(T2DM). METHODS: Four common SNPs of PGC-1alpha gene were genotyped with polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) and then analyzed with transmission-disequilibrium test (TDT) and sib transmission-disequilibrium test (STDT) in 69 T2DM pedigrees (310 individuals). Furthermore, the authors performed a case-control study to genotype Gly482Ser in 156 patients with T2DM and 111 normal glucose tolerance people without family history. RESULTS: (1)There were no positive results in four variances in TDT-STDT analysis(P> 0.05). (2)The Gly482Ser exhibited a significant difference between the two groups. GA genotype carriers were at increased risk for T2DM (OR=1.85), and there was statistically significant difference in the allele frequency between the case and control groups(P=0.046). (3) The subjects with GG genotype at position Gly482Ser had a higher HDL-C and lower LDL-C and TG levels when compared against those with GA+AA genotype in the control group without family history(P=0.043,lzP=0.046, P=0.037 respectively). CONCLUSION: This study suggested that the PGC-1alpha gene might be implicated in the pathogenesis of T2DM. But the studied SNPs in PGC-1alpha gene may not be major susceptibility ones of T2DM mellitus in Han people of Shanghai.

Asian People↗
PubMed2005

[Inhibitory effect of RNA interference on chronic myeloid leukemia bcr/abl oncogene expression].

OBJECTIVE: To investigate the inhibitory effect of RNA interference on chronic myeloid leukemia (CML) bcr/abl oncogene expression. METHODS: The small interference RNAs (siRNAs) were synthesized in vitro. K562 cells stably expressing bcr/abl gene were transfected with the siRNA by electroporation, both the non-transfected cells and non-specific siRNAs transfected cells were taken as controls. The enhanced green fluorescent protein (EGFP) plasmid was used as positive control and the transfection efficiency was detected by flow cytometry. Inhibitory effect of siRNAs was demonstrated by real-time quantitative RT-PCR and Western blots. Cell proliferation was measured by MTT assay and apoptosis by Annexin V-FITC assay. RESULTS: The transfection efficiency was about 70%. The synthesized siRNAs inhibited CML bcr/abl oncogene expression at both mRNA and protein levels. siRNAs could inhibit K562 cell proliferation to 47% and 56% at 24 h and 48 h after transfection, respectively, and induce cell apoptosis from 1.00% in control group to 15.05% and 19.4% at 24 h and 48 h respectively. CONCLUSION: At the cell level, inhibition of CML bcr/abl oncogene expression by chemically synthesized siRNAs provides the new method for anti-leukemia study.

Apoptosis↗
PubMed2005

[Determination of carbendazim and thiabendazole in tomatoes by solid-phase microextraction coupled with high performance liquid chromatography and fluorescence detection].

A novel method for the determination of carbendazim (MBC) and thiabendazole (TBZ) in tomatoes by solid-phase microextraction (SPME) coupled with high performance liquid chromatography (HPLC) and fluorescence detection was developed. The experimental conditions of SPME, including extraction fiber, extraction time, extraction temperature, desorption time, desorption solvent, desorption mode, pH value, organic solvent and ionic strength, and HPLC conditions were optimized. The SPME for MBC and TBZ was performed on a 65 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 50 min at room temperature with the solution being stirred at 1 100 r/min. The florescence detection was made at 315 nm with excitation wavelength at 280 nm. The method is linear for MBC and TBZ over the range assayed from 0.01 to 1.0 mg/kg tomatoes with the detection limits of 0.003 mg/kg and 0. 001 mg/kg and the correlation coefficients of 0.995 8 and 0.996 7, respectively. The average recoveries for MBC and TBZ were 83.5% and 85.6% with the relative standard deviations (RSDs) of 6.5% and 3.8%, respectively. The method is fast, simple, sensitive, solvent-free and suitable for the determination of MBC and TBZ in tomatoes.

Benzimidazoles↗
PubMed2004

MAPK pathway mediates the protective effects of onychin on oxidative stress-induced apoptosis in ECV304 endothelial cells.

Our recent studies have shown that onychin could protect rabbit aortic rings from lysophosphatidylcholine-induced injury by preserving endothelium-dependent relaxation and alleviating acute endothelial damage mediated by oxidative stress. However, the effect of onychin on apoptosis of endothelial cells induced by oxidative stress was not evaluated. In the present study, we investigated the effect of onychin on Hydrogen Peroxide (H2O2) induced apoptosis of ECV304 endothelial cells. Cultured human umbilical vein endothelial cell line (ECV304) was pretreated with vehicle (DMSO), genistein, or different concentrations of onychin (0.1, 0.3, 1, 3, and 10 micromol/L) for 30 minutes and then exposed to 1 mmol/L H2O2 for 24 hours. Cell apoptosis was determined by TUNEL and flow cytometric analysis. Meanwhile, Western-blot was used to measure the expression of phospho-ERK1/2, phospho-p38 and caspase-3. Our data showed that onychin treatment exhibited a protective effect on ECV304 endothelial cells from H2O2-induced apoptosis in a concentration-dependent manner. Moreover, onychin attenuated H2O2-induced phosphorylation of p38MAPK and increased H2O2-induced phosphorylation of ERK1/2. Furthermore, onychin decreased the activation of caspase-3. The opposing effects of onychin on phosphorylation levels of p38MAPK and ERK1/2, and its caspase-3 inhibition might play a role in the beneficial effect of onychin on endothelial injury.

Alkaloids↗
PubMed2004

Molecularly engineered poly(ortho ester) microspheres for enhanced delivery of DNA vaccines.

Genetic vaccination using plasmid DNA presents a unique opportunity for achieving potent immune responses without the potential limitations of many conventional vaccines. Here we report the design of synthetic biodegradable polymers specifically for enhancing DNA vaccine efficacy in vivo. We molecularly engineered poly(ortho ester) microspheres that are non-toxic to cells, protect DNA from degradation, enable uptake by antigen-presenting cells, and release DNA rapidly in response to phagosomal pH. One type of microsphere of poly(ortho esters) that releases DNA vaccines in synchrony with the natural development of adaptive immunity, elicited distinct primary and secondary humoral and cellular immune responses in mice, and suppressed the growth of tumour cells bearing a model antigen. This polymer microparticulate system could, with further study, have implications for advancing the clinical utility of DNA vaccines as well as other nucleic-acid-based therapeutics against viral infections and cancer.

Adjuvants, Immunologic↗
PubMed2004

Insulin resistance and endothelial dysfunction in type 2 diabetes patients with or without microalbuminuria.

OBJECTIVE: To evaluate the relationship between insulin resistance and endothelial function in type 2 diabetes patients with or without microalbuminuria and to explore the pathophysiological mechanisms of the increased macrovascular risk in type 2 diabetes mellitus. METHODS: Twelve type 2 diabetes patients with microalbuminuria (urinary albumin 30-300 g/mg creatinine, DM-MA) and 12 type 2 diabetes patients without microalbuminuria (urinary albumin <30 g/mg creatinine, DM-NA) were recruited, matched for their sex, age, body mass index (BMI), diabetes duration, antidiabetic therapy. Their hemoglobin (HbA1C) was less than 7.5% and the blood pressure was lower than 140/90 mmHg. None had evidence of macrovascular disease and serum cholesterol levels were normal. Twelve healthy volunteers (C) were enrolled as controls. All subjects received a hyperinsulinemic euglycemic clamp study (insulin infusion rate, 120 mU/m2/min) to assess the peripheral glucose disposal rate (GDR) in the steady state and had a high-resolution ultrasonography to measure vasodilation in the brachial artery diameter in response to reactive hyperemia (endothelium-dependent) and administration of glyceryl trinitrate (endothelium-independent). Plasma free fatty acids (FFAs), plasminogen activator inhibitor type I (PAI-1), and von Willebrand factor (vWF) were also measured. RESULTS: The GDR was lower in type 2 diabetes patients with microalbuminuria (7.90 +/- 1.79 mg/kg/min) than in patients without microalbuminuria (9.46 +/- 1.59 mg/kg/min, P<0.05), and the GDR in both diabetes groups was decreased, compared with the findings from the healthy control group (13.06 +/- 1.98 mg/kg/min, P<0.01). Plasma FFAs concentration was different among the three groups (DM-MA-1008 +/- 229 mol/l, DM-NA-675 +/- 201 mol/l, P<0.01; C-364 +/- 169 mol/l, P<0.01). Endothelium-dependent vasodilation was impaired in the microalbuminuric patients (8.0 +/- 3.8%) compared with the normoalbuminuria patients (9.7 +/- 4.3%, P>0.05) and the healthy controls (14.2 +/- 5.0, P<0.05). Plasma PAI-1 and vWF levels increased in the microalbuminuric patients (61.9 +/- 18.2 ng/ml, 126.8 (76.5-212.7) %) compared with the levels in the normoalbuminuric patients (45.4 +/- 16.3 ng/ml, 87.9 (84.2-114) %) (PAI-1, P<0.05; vWF, P>0.05) and in the healthy controls (33.6 +/- 10.6 ng/ml, 67.2 (61.5-75.4) %, both P<0.01). In addition, the partial correlation analysis revealed a significant positive correlation between GDR and endothelium-dependent vasodilation (r=0.465, P<0.01, n=36), and a negative correlation between GDR and plasma FFA levels (P<0.05). CONCLUSIONS: Compared with type 2 diabetes patients with normoalbuminuria, patients with microalbuminuria had more severe insulin resistance, more prominent endothelial dysfunction, and higher plasma FFA, PAI-1, and vWF levels. Therefore we speculate that insulin resistance and endothelial dysfunction may act within the metabolic syndrome to increase the cardiovasular risk in this subset of patients, and improving insulin resistance and endothelial dysfunction may reduce the morbidity and mortality from macrovascular complications in type 2 diabetes patients.

Aged↗
PubMed2004

Characterization of porcine circovirus type 2 in Taiwan.

In an effort to understand the genetic diversity of porcine circovirus type 2 (PCV2) and the prevalence of PCV2 infection in Taiwanese herds, we have sequenced the complete genomes from PCV2-infected specimens and individually measured the antibody titer against PCV2 from pigs reared in Taiwan between the years 2000 and 2002. A total of 623 specimens originating from pigs displaying varied clinical signs were screened with the polymerase chain reaction (PCR). Results showed that 309 pigs (49.6%) tested positive for PCV2. Eight of the positive specimens were used for the amplification of the complete viral genome. Sequence comparison of the complete genomes indicated that the 8 Taiwanese PCV2 isolates shared 95-99% similarity. Phylogenetic analysis of all 40 PCV2 isolates from North America, Europe, Asia and Taiwan revealed that those isolates were grouped together in one large group containing two minor subgroups. The Taiwanese PCV2 isolates were classified into the two minor subgroups. The prevalence of serum antibodies to PCV2 in pigs was investigated, and results showed that approximately 83.5% of the pigs in Taiwan were seropositive. Finishing pigs possess the highest titers of antibodies, while 9-week-old pigs contained the lowest titers for specific antibodies. Our results suggest that PCV2 infections have become common in Taiwanese pig farms.

Age Factors↗