Search PubMed⌕ Search

Biomedical subjects

S Yao

Publications and source records attributed to S Yao.

At least 37 records · Page 2Linked to original sources
PubMed2001

A kinetic study on the interaction of deprotonated purine radical cations with amino acids and model peptides.

By use of pulse radiolysis techniques, the radical cations of purine nucleotides have been successfully produced by the SO4- ion oxidation. Time-resolved spectroscopic evidence is provided that the one-electron-oxidized radicals of dAMP and dGMP can be efficiently repaired by aromatic amino acids (including tyrosine and tryptophan) via electron transfer reaction. As a model peptide, Arg-Tyr-AcOH was also investigated with regard to its interaction with deprotonated purine radical cations. The rate constants of the electron transfer reactions were determined to be (1 approximately 5) x 10(8) dm(3) mol(-1) s(-1). These results suggest that the aromatic amino acids in DNA-associated proteins may play some role in electron transfer reactions through DNA.

Amino Acids↗
PubMed2001

Potent antioxidative potential of propofol during cardiopulmonary bypass in the adult.

The potent antioxidative potential of propofol during cardiopulmonary bypass (CPB) in adults was investigated. The selected 30 patients receiving open heart surgery under CPB were randomly divided into group A and group B. The patients in the group A and group B were given propofol (0.1 mg.kg-1.min-1) and fentanyl (5 micrograms.kg-1.min-1) respectively to maintain anesthesia after aorta was cross-clamped. Blood samples were drawn pre-anesthesia, pre-CPB, at 30 min of CPB, at the end of CPB, at 1 h after CPB, at the end of operation, at 12 and 24 h postoperatively. RBC suspension was prepared and erythrocyte glucose-6-phosphate dehydrogenase (G-6-PD) and phosphofructokinase (PFK) activities, total erythrocyte reduced glutathione (GSH) and oxidized GSH (GSSG) were assayed and GSH/GSSG ratio was calculated. In the group A, G-6-PD and PFK activities and GSH/GSSG ratio were almost uneventfully during CPB and postoperatively. In the group B, G-6-PD activity was increased and PFK activity and GSH/GSSG ratio decreased significantly from 30 min of CPB until 12 h postoperatively. It was demonstrated that propofol could obviously attenuate free radical activity during CPB, while fentanyl has no effect on free radical reduction. Propofol could be beneficial as an anesthetic in patients presenting pathologies associated with free radical reactions during CPB.

Adult↗
PubMed2001

The protective effect of propofol on erythrocytes during cardiopulmonary bypass.

To evaluate the relationship between erythrocyte injury and intracellular calcium ion overload, and the protective effect of propofol on erythrocytes during cardiopulmonary bypass (CPB), 40 children with congenital heart diseases who underwent surgical repair under CPB were studied. The patients were randomly divided into two groups: control group (group C) and propofol group (group P). Anesthesia was maintained in the patients in group P with 6 mg.kg-1.h-1 propofol, and those in the group C inhaled 1%-2% isoflurane. The blood samples were taken before CPB, at the 30th min of CPB, at the end of CPB, and 2 h and 24 h after CPB to measure the content of erythrocyte intracellular calcium ion (E-Ca2+), Ca(2+)-Mg(2+)-ATPase and Na(+)-K(+)-ATPase activities, index filtration of erythrocytes (IF), mean corpuscular volume (MCV) and the concentration of plasma free hemoglobin (F-HB). Results showed that in the control group, E-Ca2+, IF, MCV and F-Hb were gradually increased and Ca(2+)-Mg(2+)-ATPase and Na(+)-K(+)-ATPase activities were decreased. The increase of E-Ca2+ was linearly paralleled to IF, MCV and F-Hb. In propofol group, all the above-mentioned parameters were significantly improved (P < 0.05). This study suggests that erythrocyte injury is related to elevation of intracellular calcium during CPB and propofol has a protective effect on erythrocyte injury.

Anesthetics, Intravenous↗
PubMed2001

Gradient refractive index of the crystalline lens of the Black Oreo Dory (Allocyttus Niger): comparison of magnetic resonance imaging (MRI) and laser ray-trace methods.

The gradient refractive index of the crystalline lens in the Black Oreo Dory (Allocyttus Niger) was determined using two methods; an optimisation program based on finite ray-tracing and the path of laser beams through the lens, and magnetic resonance imaging (MRI) and the linear relationship between refractive index and nuclear transverse relaxation rates. The methods showed good agreement in the cortical zone of the lens, but the lack of free water in the core of the lens made MRI measurement impossible in this region. The laser-optimisation method gave mean values of 1.368 and 1.543 for the surface and core refractive indices respectively, with a radial distribution for the gradient refractive index given by n(r)=1.543-0.121r2-0.033r4-0.021r6.

Animals↗
PubMed2001

Prediction of partition coefficient and toxicity for benzaldehyde compounds by their capacity factors and various molecular descriptors.

The log Kow and log Sw values of 14 substituted benzaldehyde compounds were determined by the shake-flask method. Acute toxicities of 14 substituted benzaldehyde compounds to Daphnia magna were recorded. Their capacity factors (k') were determined by reversed phased high-performance liquid chromatography (RP-HPLC) on C18 column and methanol-water eluent. Molecular connectivity indices, the linear solvation energy relationships (LSER) parameters, and quantum chemical parameters were calculated for the tested chemicals and used to develop quantitative structure-retention relationship (QSRR) and quantitative structure-property/activity relationship (QSPR/QSAR). Results demonstrated that the molecular connectivity indices, LSER parameters, and quantum chemical parameters could be used to predict the k' for compounds studied, LSER method was more accurate. The results also show that chromatographic retention data, log k', can be used to predict log Kow and log Sw for tested compounds. The log k'w can be directly utilized as hydrophobic descriptors to predict the toxicity to D. Magna for benzaldehyde compounds.

Benzaldehydes↗
PubMed2001

The role of cyclooxygenase-2 in prostate cancer.

Cyclooxygenase-2 (COX-2) is the inducible isozyme of COX, a key enzyme in the conversion of arachidonic acid to prostaglandins and other eicosanoids. COX-2 is highly expressed in a number of human cancers and cancer cell lines, including prostate cancer. We studied the immunohistochemical expression of COX-2 in the human prostate gland. The enzyme is strongly expressed in smooth muscle cells of both the normal and cancerous prostate. Its expression in noncancerous epithelial cells is limited to the basal cell layer. In prostatic inflammation, luminal epithelial cells surrounded by lymphocytes are induced to express the enzyme. COX-2 is expressed in the epithelial cells of high-grade prostatic intraepithelial neoplasia and cancer. We have demonstrated that treatment of human prostate-cancer cell lines with a selective COX-2 inhibitor induces apoptosis both in vitro and in vivo. The in vivo results also indicate that the COX-2 inhibitor decreases tumor microvessel density and angiogenesis. COX-2 inhibitors can prevent the hypoxic upregulation of a potent angiogenic factor, vascular endothelial growth factor. These results indicate that COX-2 inhibitors may, therefore, serve as effective chemopreventive and therapeutic agents in cancer of the prostate.

Animals↗
PubMed2001

Application of double-impedance system and cyclic voltammetry to study the adsorption of fullerols (C60(OH)n) on biological peptide-adsorbed gold electrode.

The adsorption of fullerols (C60(OH)n) on glutathione-adsorbed gold electrode was characterized by using double-impedance system, i.e., electrochemical quartz crystal impedance and electrochemical impedance spectroscopy, and cyclic voltammetry. The time courses of piezoelectric parameters were used to reflect the changes of interfacial physical properties, such as mass, density-viscosity, and dielectric constant, during the adsorptions of peptide and fullerols onto electrode. The electrochemical impedance based on the simple equivalent electric network were also simultaneously measured and provided electrochemical interface information, e.g., double-layer capacitance and charge-transfer resistance. It was found that the double-impedance responses were varied with the forms of glutathione. It was also shown that the frequency curves due to the adsorption of oxidized (GSSG) and reduced (GSH) glutathione could be exhibited as different kinetic equations. The heterogeneous charge-transfer rate constants of ferricyanide/ferrocyanide before and after the peptide and fullerols adsorption were determined by CV and EIS methods. The results showed that the proposed method has potential applications in interfacial studies of biomaterials, since these combined techniques have advantages in real time providing multidimensional piezoelectric and electrochemical impedance information.

Adsorption↗
PubMed2001

A study of a new TSM bio-mimetic sensor using a molecularly imprinted polymer coating and its application for the determination of nicotine in human serum and urine.

A new bio-mimetic quartz crystal thickness-shear-mode (TSM) sensor, using an imprinted polymer coating as the sensitive material, has been fabricated and applied to the determination of nicotine (NIC) in human serum and urine. The molecularly imprinted polymer (MIP) was synthesized using NIC as the template molecule and methacrylic acid (MAA) as the functional monomer. The sensor showed high selectivity and a sensitive response to NIC in aqueous system. The linear response range of the sensor was between 5.0 x 10(-8) and 1.0 x 10(-4) M with a detection limit of 2.5 x 10(-8) M. The viscoelasticity of the coating in the air and in liquid has been studied by the impedance spectrum. The MIP sensor was stable and exhibited effective reproducibility. Satisfactory results were achieved in the detection of the real samples.

Biosensing Techniques↗
PubMed2001

Ion-selective piezoelectric sensor for niacinamide assay in serum and urine.

An ion-selective piezoelectric (ISP) sensor was successfully applied for the determination of niacinamide in serum and urine. By coating a polyvinylchloride membrane containing niacinamide-silicotungstate on one electrode of a thickness-shear mode piezoelectric quartz crystal, the ISP device can adsorb niacinamide selectively. The amount of coating applied to the crystal was calculated from the Sauerbrey equation by monitoring the frequency change. The logarithm of the frequency shift was linear with the logarithm of niacinamide concentration over the range from 1.0 x 10(-9) to 1.0 x 10(-3) M with a detection limit of 1.0 x 10(-9) M at pH 7.0. Influencing factors were investigated and optimized. The results for real samples obtained by the proposed method were in good agreement with those obtained by the conventional methods.

Electrodes↗
PubMed2001

Aromatase-deficient (ArKO) mice accumulate excess adipose tissue.

Aromatase is the enzyme which catalyses the conversion of C19 steroids into C18 estrogens. We have generated a mouse model wherein the Cyp19 gene, which encodes aromatase, has been disrupted, and hence, the aromatase knockout (ArKO) mouse cannot synthesise endogenous estrogens. We examined the consequences of estrogen deficiency on accumulation of adipose depots in male and female ArKO mice, observing that these animals progressively accrue significantly more intra-abdominal adipose tissue than their wildtype (WT) litter mates, reflected in increased adipocyte volume and number. This increased adiposity was not due to hyperphagia or reduced resting energy expenditure, but was associated with reduced spontaneous physical activity levels, reduced glucose oxidation, and a decrease in lean body mass. Elevated circulating levels of leptin and cholesterol were present in 1-year-old ArKO mice compared to WT controls, as were elevated insulin levels, although blood glucose was unchanged. Associated with these changes, the livers of ArKO animals were characterised by a striking accumulation of lipid droplets. Our findings demonstrate an important role for estrogen in the maintenance of lipid homeostasis in both males and females.

Adipose Tissue↗
PubMed2001

Development of a thickness shear mode acoustic sensor based on an electrosynthesized molecularly imprinted polymer using an underivatized amino acid as the template.

The preparation and characterization of electrosynthesized poly(o-phenylenediamine) (iPoPD) as a molecular imprinting material were studied by an in situ quartz crystal impedance method. The changes of delta f0, delta R1, delta L1 and delta C0 suggest that the polymer film was compact and rigid. The thickness shear mode (TSM) acoustic sensor modified with this material exhibits molecular recognition ability to the template molecule of DL-phenylalanine. In the range 2-20 mM, a linear relationship between the frequency shift delta f0 and logC was found from the calibration graph. Scatchard analysis of the relevant calibration graph offers information on the equilibrium of the binding interaction and the recognition sites. Using this electropolymerization technology, the preparation of the sensor was very simple and the reproducibility of preparation was very good. In particular, it offers possibilities for sensor miniaturization.

Journal Article↗
PubMed2001

A piezoelectric biomimetic sensor for aminopyrine with a molecularly imprinted polymer coating.

A molecularly imprinted polymer for aminopyrine was synthesized using methacrylic acid as functional monomer. The polymer was employed as the recognition element of a piezoelectric bulk acoustic wave biomimetic sensor for aminopyrine. Influencing factors were investigated in detail and optimized. This sensor exhibited high selectivity and sensitivity to aminopyrine. The response range of the sensor was between 5.0 x 10(-8) and 1.0 x 10(-4) M with a detection limit of 2.5 x 10(-8) M in the aqueous system. Scatchard analysis with UV spectrophotometry showed that the same class of binding sites was formed in the molecularly imprinted polymer in the studied concentration range, and the dissociation constant and the apparent maximum number of these binding sites were estimated to be 2.29 mM and 165.0 mumol g-1 dry polymer, respectively. Impedance analysis was employed to verify the imprinting effect and lack of variation in the viscoelasticity of the polymer coating during detection.

Aminopyrine↗
PubMed2001

Construction and application of phenytoin anion-selective electrode based on bulk acoustic wave (BAW) sensing technique.

This paper describes the construction of an anion-selective bulk acoustic wave (BAW) sensor for the direct determination of phenytoin sodium for the first time. Based on the sensitive mass response of a piezoelectric quartz crystal (PQC) and selective adsorption-desorption across the modified film, the BAW sensor was fabricated by coating a polyvinylchloride (PVC) film containing activator on one side of a PQC. The method was found to be sensitive, rapid and easy to handle without pretreatment of the sample. The logarithm of the frequency shift of the PQC shows a linear relationship to the logarithm of the concentration of phenytoin over the range 6.7 x 10(-8)-8.0 x 10(-4) M with a detection limit of 1.0 x 10(-8) M at pH 10.0. Recoveries were in the range 98.5-102.0%. Influencing factors were examined and optimized. Also discussed is the preliminary application of the phenytoin BAW sensor in serum and injection. The results for real samples obtained by the proposed method agreed with those obtained by conventional methods.

Anions↗
PubMed2001

Fast repair of the radical cations of dCMP and poly C by quercetin and rutin.

The effects of quercetin and rutin on the repair of the radical cations of dCMP and poly C were studied using the technique of pulse radiolysis. The radical cations of dCMP and poly C were formed by the reaction of dCMP and poly C with SO( 4)(-). After pulse irradiation of nitrogen-saturated aqueous solutions containing dCMP, 20 mM K(2)S(2)O(8), 200 mM t-BuOH and either rutin or quercetin, the initially formed radical cation of dCMP, detected spectrophotometrically, rapidly decayed with the concurrent formation of the phenoxyl radical of rutin or quercetin within 8-40 micros. The repair efficiencies of the tested compounds towards the poly C radical cation were also determined using the same procedure. The results indicate that dCMP and poly C radical cations can be rapidly repaired by quercetin and rutin. The rate constants of the repair reactions were determined to be 4.3-8.8x10(8) M/s and 1.5-3.6x10(8) M/s for dCMP and poly C radical cations, respectively. Together with findings from our previous studies, the present results demonstrate that non-enzymatic fast repair may be a universal form of repair involving phenolic antioxidants.

Antioxidants↗
PubMed2001

Bedside tracheostomy in the intensive care unit: a prospective randomized trial comparing open surgical tracheostomy with endoscopically guided percutaneous dilational tracheotomy.

OBJECTIVES: Objectives of the study were 1) to analyze the complication incidence and resource utilization of two methods of bedside tracheostomy and 2) to define selection criteria for bedside tracheostomy. STUDY DESIGN: Prospective randomized trial in the setting of a tertiary care center at a university hospital. METHODS: One hundred sixty-four consecutive intubated patients selected for elective tracheostomy were enrolled. One hundred patients met selection criteria for bedside tracheostomy and were randomly assigned to either open surgical tracheostomy (50) or endoscopically guided percutaneous dilational tracheotomy(50). The remaining 64 patients received open surgical tracheostomies in the operating room. Main outcome measures were 1) perioperative and postoperative complication incidence and 2) resource utilization. RESULTS: Patients meeting our selection criteria for bedside tracheostomy had a significantly reduced perioperative complication rate compared with those who failed to meet these criteria, and subsequently underwent tracheostomy placement in the operating room (5% vs. 20%, P less than or equal to.01). No statistically significant difference was found in the perioperative complication incidence between the two methods of bedside tracheostomy. However, percutaneous tracheostomy placement at the bedside resulted in a significant increase in postoperative complication incidence (16% vs. 2%, P <.05) and incurred an additional patient charge of $436 per bedside procedure. CONCLUSIONS: This investigation prospectively confirms the safety of bedside tracheostomy placement in properly selected patients. Complication incidence and resource utilization are defined for two methods of bedside tracheostomy. The results of this study confirm that open surgical tracheostomy represents the standard of care in bedside tracheostomy placement by providing a more secure airway at a markedly reduced patient charge. These findings will aid in the development of protocols and pathways for surgical airway management in critically ill patients to maximize cost-effective, high-quality care.

Adult↗
PubMed2001

Personality profiles and the prediction of categorical personality disorders.

Personality disorders (PDs) are usually construed as psychiatric categories characterized by a unique configuration of traits and behaviors. To generate clinical hypotheses from normal personality trait scores, profile agreement statistics can be calculated using a prototypical personality profile for each PD. Multimethod data from 1,909 psychiatric patients in the People's Republic of China were used to examine the accuracy of such hypotheses in the Interpretive Report of the Revised NEO Personality Inventory. Profile agreement indices from both self-reports and spouse ratings were significantly related to PD symptom scores derived from questionnaires and clinical interviews. However, accuracy of diagnostic classification was only modest to moderate, probably because PDs are not discrete categorical entities. Together with other literature, these data suggest that the current categorical system should be replaced by a more comprehensive system of personality traits and personality-related problems.

Adolescent↗
PubMed2001

Phosphorylation of the RNA polymerase II carboxy-terminal domain by the Bur1 cyclin-dependent kinase.

BUR1, which was previously identified by a selection for mutations that have general effects on transcription in Saccharomyces cerevisiae, encodes a cyclin-dependent kinase that is essential for viability, but none of its substrates have been identified to date. Using an unbiased biochemical approach, we have identified the carboxy-terminal domain (CTD) of Rpb1, the largest subunit of RNA polymerase II, as a Bur1 substrate. Phosphorylation of Rpb1 by Bur1 is likely to be physiologically relevant, since bur1 mutations interact genetically with rpb1 CTD truncations and with mutations in other genes involved in CTD function. Several genetic interactions are presented, implying a role for Bur1 during transcriptional elongation. These results identify Bur1 as a fourth S. cerevisiae CTD kinase and provide striking functional similarities between Bur1 and metazoan P-TEFb.

Animals↗