Biomedical subjects

Y Yang

Publications and source records attributed to Y Yang.

At least 523 records · Page 29Linked to original sources

PubMed2000

[The selection of fluoroacetate-resistant mutant from E. coli MMR204 and its influence on the expression of heterologous GL-7ACA acylase].

In the cultivation of gene engineered strain of Escherichia coli on glucose medium, excretion and accumulation of acetic acid inhibit not only cell growth but also the the expression of heterologous protein. It is obvious that the desirable host strain maintaining acetate at a low level is one of the approaches to increase the production of recombinant protein. The present article deals with the selection of mutants of E. coli DP19, DP8, which grow on the medium containing pyruvate as the sole carbon source in the presence of 50 mmol/L fluoroacetic acid. It is shown that mutant DP19 is defective in its phosphotransacetylase(PTA) activity and accumulates less acetate in the medium, while DP8 is defective in acetate kinase (ACK) and accumulates similar level of acetate comparing with its parent. Using pta- mutant E. coli DP19 as host, the expression of GL-7ACA acylase gene on the recombinant plasmid pMR24 is improved, and the yield of enzyme activity in flask fermentation is about twice as much as its parent.

Acetate Kinase↗

PubMed2000

[A noninvasive method for radial pulse-wave velocity and the determinants of pulse-wave velocity].

An effective experimental method has been proposed and used to determine the pulse-wave velocity (PWV) of 257 radial pulse signals. Experimental results show that, compared with the normal pulse, the wiry pulse has an increased PWV(P < 0.01 or P < 0.05), the thready pulse has a decreased PWV(P < 0.05), but the PWV of the smooth pulse is not significantly different from the normal's (P > 0.05). PWV highly correlates with the artery blood pressure. The possible determinants of PWV are analyzed and discussed in reference to clinical diagnosis.

Blood Pressure↗

PubMed2000

[An experiment of gut barrier function damage following multiple firearm injuries in a porcine model].

OBJECTIVE: To study the characteristics and pathogenesis of gut barrier damage following multiple firearm injuries in porcine models. METHODS: 24 small pigs were divided into 4 groups (n = 6 each): control group(group C), group H (gunshot-induced tangential fracture of parietal bone), group L (gunshot-induced comminuted fracture of bilateral femora) and group M (combined group H + L). Gastric intramucosal pH (pHi), plasma endotoxin in portal vein, and plasma D-lactic acid were measured and blood samples were cultured at different time intervals after trauma. The animals were sacrificed at 72 h and ileum tissues were harvested for pathological examination and DAO measurement. RESULT: In group M at 72 h, pHi was significantly lower than that of group H and L(P < 0.01), plasma endotoxin level was significantly higher than that of group H(P < 0.01) and group L(P < 0.05), D-lactic acid level was significantly higher than that of group H(P < 0.01), and bacterial isolation rate in blood was much higher than that of group H and L(P < 0.05). Necrosis and peeling off were revealed at ileum villus top in all trauma groups, especially in group M, in which ileum DAO content also declined in most cases. CONCLUSION: Multiple traumas were prone to gastrointestinal ischemia even when hemorrhagic shock did not take place. The damage of gut barriers in multiple traumas were more severe than that in one-site trauma, which enhanced the incidence of intestinal endotoxin and bacterial translocation and trend to cause enterogenous infection.

Amine Oxidase (Copper-Containing)↗

PubMed2000

[Surgical treatment of primary intracerebral neoplasms only presenting with epilepsy].

OBJECTIVE: To analyse the histopathology and the factors influencing the outcome of surgical treatment of primary intracerebral neoplasms only presenting with epilepsy. METHODS: 55 patients with primary intracerebral tumors presenting with epilepsy without other neurologic signs were retrospectively reviewed. RESULTS: 54(98.2%) cases were histologically diagnosed as gliomas among which 42(76.4%) were low-grade and 12(21.8%) high-grade. The incidence of complications for tumor removals was 32.7%. Of the 41 patients who had postoperative follow-up more than 6 months after operation, 20(48.8%) were seizure-free, 3 were rare, 4 were improved, and 14 (34.1%) had no appreciable reduction in seizure frequency. The position of the tumors was significantly correlated with the incidence of postoperative complications and the postoperative seizure control (P < 0.05). The incidence of postoperative complications for frontal and parietal tumors was higher than that for temporal tumors, while the temporal tumors had better postoperative seizure control than the frontal and the parietal ones. CONCLUSIONS: Most of the primary intracerebral tumors only presenting with epilepsy were low-grade gliomas. The position of tumors was an important factor influencing the extent of surgical removal and the postoperative seizure control.

Adolescent↗

PubMed2000

[Changes of plasma nitric oxide and tumor necrosis factor-alpha in lung elastase injury induced inflammatory response of hamster].

OBJECTIVE: To investigate the role of the NO and TNF-alpha in lung elastase injury induced inflammatory response of hamster. METHODS: Lung elastase injury induced inflammatory hamster model was established. NOS activity in airway epithelial cells and lung monocytes/macrophage, as well as the serum content of NO and TNF-alpha were measured respectively. RESULTS: The results indicated that iNOS activity in epithelium and monocytes/macrophages were significantly enhanced. In the early period of inflammation the NO and TNF-alpha content in serum increased obviously and maintained in a high level (P < 0.001). CONCLUSIONS: This Study suggested that both NO and TNF-alpha are important mediators participating in the lung elastase injury-induced inflammatory response. Our data suggested NO might play a regulatory role in the release of TNF-alpha.

Animals↗

PubMed2000

Effect of coxsackievirus b3 on ion channel currents in rat ventricular myocytes.

OBJECTIVE: To investigate the effects of coxsackievirus B3(CVB3) on ion channel currents in rat ventricular myocytes. METHODS: Rat hearts were isolated with collagenase to acquire single ventricular myocytes, L-type voltage-dependent calcium channel (VDCC) current (I(Ca)), Na+ current (I(Na)), outward potassium current (I(out)), inwardly rectifying potassium current(I(KI)) were recorded using whole cell patch clamp techniques. RESULTS: CVB3 infection increased I(Ca) and I(out), while decreased I(KI); but it had no obvious effect on I(Na). CONCLUSION: The effects of CVB3 an I(Ca), I(out), I(KI) may be one of the mechanisms of myocytes damage and the occurrence of abnormal electroactivities induced by CVB3 infection.

Animals↗

PubMed2000

The effect of left ventricular diastolic dysfunction on the pathogenesis of angina decubitus.

OBJECTIVE: To investigate the effect of left ventricular diastolic dysfunction on the pathogenesis of angina decubitus (AD). METHODS: The study population consisted of three groups: 20 individuals without cardiovascular studied as group I. Group II included 20 patents with coronary artery disease and without AD. Thirty-one patients with AD and ejection fraction (EF) > 50% were studied as group III. Group II and III were matched for age, EF and extent of coronary artery disease. RESULTS: Left ventriculography (LVG) showed that left ventricular (LV) first 1/3 filling fraction (1/3FF) was significantly lower in group III than in group II and I (both P < 0.001), but LV late 1/3 FF was much higher in group III than in group II and I (P < 0.05, P < 0.01). Left ventricular end-diastolic pressure (LVEDP) was markedly increased before and after LVG in group II and III as compared with group I (both P < 0.05, both P < 0.001). The difference of LVEDP caused by left atrial contraction (left atrial contraction pressure difference, LACPD) before and after LVG was much higher in group III than in group I ( P < 0.01, P < 0.001). However, there we significant differences in LVEDP and in LACPD between before and after LVG only in group III (both P < 0.01). CONCLUSION: The patients with AD have LV diastolic dysfunction, which may be closely related to the pathogenesis of angina decubitus.

Adult↗

PubMed2000

[In situ time-resolved FTIR studies of HCOOH oxidation on Pt(100)/Sb electrodes].

The electrocatalytic oxidation of formic acid on Pt(100)/Sb electrodes of different coverage of Sb was investigated by using electrochemical techniques and in situ time-resolve FTIRS. The results demonstrated that the dissociative adsorption of formic acid was inhibited by the presence of Sbad on Pt(100) surface, as a consequence HCOOH can be oxidized directly into CO2 via reactive intermediates. The rate of oxidation of formic acid varied with the coverage of Sbad. It was revealed that at a Sbad coverage of 0.24 the Pt(100)/Sb electrode exhibited the highest electrocatalytic activity for HCOOH oxidation.

English Abstract↗

PubMed2000

[Study on the infrared spectra of metallic clusters containing R2dtc ligand and V = O group].

This paper reports the features and regularities of the infrared spectra for two kinds of complexes containing R2dtc ligand. The cubane-like clusters containing R2dtc ligand possess weak and wide peaks at 400-500 cm-1 assigned to M-mu 3S vibration, while the peaks at 330-380 cm-1 and 1,470-1,510 cm-1 can be assigned to M-Sdtc and C-N vibrations, respectively. The nu(C-N) and nu(C = S) vibrations for Me2dtc-cubane cluster exhibit blue shift and red shift, respectively, when compared with those of other R2dtc ones. This would be attributed to the strong super-conjugation of the methyl group. The M-mu 3S vibrations for both types of complexes [V2Cu2S4(R2dtc)2(PhS)2]2- and [VCu4S4(R2dtc)n(PhS)4-n]3- (n = 0, 1, 2) occur at 480 and 465 cm-1, respectively. This small difference becomes a useful indication to distinguish the two types of clusters. Cluster complexes containing (R2dtc)2V2O2(mu-S)2 structural unit show the V = O vibration in the range of 844-970 cm-1. It is noted that (Et4N)[V3S2O3(Et2dtc)3] contains two sets of the V = O bonds corresponding to two sets of V = O vibrations at 970 and 844 cm-1. An additional coordination of the V = O bond to another metal atom obviously weakens the V = O bond to give rise to the red shift of the infrared frequency. Similar red shifts were also observed for other complexes and were discussed.

English Abstract↗

PubMed2000

[In situ FTIR spectrocopic investigations of 1,3-butanediol oxidation on Sb and S modified Pt electrodes].

In the present paper, we studied the surface structure effect of Pt electrode modified with antimony and sulfur adatoms towards 1,3-Butanediol oxidation. The results demonstrated that the modification of Sb and S both inhibited the dissociative adsorption of 1,3-Butanediol into CO, which is the main source of self-poisoning in electrocatalysis of small organic molecules. At lower potentials, the principal oxidation pathway of 1,3-Butanediol on Pt/Sbad electrode is towards the production of C=O. However, at higher potentials, the products of CO2 increased. The presence of S(ad) inhibited the oxidation of 1,3-BD at low potentials(< 0.8 V), and yield mainly acid species as products at higher potentials(> 0.8 V).

Antimony↗

PubMed2000

[In situ FTIR studies of CO adsorption on palladium loading zeolite electrode].

Adsorption of CO on palladium loading zeolite electrode supported on Pt or GC substrate was studied by in situ MSFTIR spectroscopy. The results demonstrated that the geometry of faujasite supercages favors the formation of bridge-bonded CO species. The enhanced IR adsorption of CO adsorbed on Pd clusters located in the supercages of zeolite has been observed for the first time, which is a new phenomenon and differs from the abnormal infrared effects discovered by our group and the surface enhanced infrared absorption phenomenon reported in the literature.

English Abstract↗

PubMed2000

[Studies on synthesis and IR spectrum of nickel salicylates complexes].

Nickel salicylates complexes were synthesized with the rheologic phase reaction method. The composition of these complexes were confirmed by elemental analysis, TG and IR, the principal infrared absorption peaks were assigned for the region 4,000-400 cm-1. The IR spectra indicated that a hydroxyl group on Ni atom was occurred and so absorption peaks of hydroxyl group were shifted obviously to higher frequency in nickel monosalicylates.

Chelating Agents↗

PubMed2000

[Determination of hydrogen in 2,091 Al-Li alloy].

High volatility element Li exists in 2091 Al-Li alloy, and makes the difficulty for the determination of hydrogen. A lot of tests were done, for example, how to distinguish the body and surface hydrogen, to choice heating power, heating time and the size of sample. Then the analytical method is established and many discussions were done. The reproducibility and accuracy is satisfactory, and compared with the Russian Al-Li alloy hydrogen standard sample.

English Abstract↗

PubMed2000

[Synthesis and characterization of complex of NdL3.2H2O].

The binary solid complexes using rare earth ion Nd3+ with the ligand L (L = O-chorophenoxyacetic acid and 3-methoxybenzoic acid) has been synthesized in this work. The chemical formula of the complex was determined to be NdL3.2H2O by elemental analysis. The composition structure and properties of this type of complex were tentatively investigated by the analysis of molar conductivity, TG-DTA, IR and UV.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2000

[Synthesis and characterization of complex Eu (C8H7O3)3.C12H8N2.H2O].

A new complex Eu (C8H7O3)3.C12H8N2.H2O has been synthesized. The complex was deduced tentatively that the Eu (III) ion was chelated by the bidentate ligand 3-methoxybenzoic acid in bridging mode by the characterization of element analysis, molar electric conductance, IR, UV and 1H NMR spectra.

English Abstract↗

PubMed1999

Probing the folding pathways of long R(3) insulin-like growth factor-I (LR(3)IGF-I) and IGF-I via capture and identification of disulfide intermediates by cyanylation methodology and mass spectrometry.

This report describes an integrated investigation of the refolding and reductive unfolding of insulin-like growth factor (IGF-I) and its variant, long R(3) IGF-I (LR(3)IGF-I), which has a Glu(3) to Arg(3) substitution and a hydrophobic 13-amino acid N-terminal extension. The refolding performed in glutathione redox buffer was quenched at different time points by adjusting the pH to 2.0-3.0 with a 1 N HCl solution of 1-cyano-4-dimethylaminopyridinium tetrafluoroborate, which trapped intermediates via cyanylation of free sulfhydryl groups. The disulfide structure of the intermediates was determined by chemical cleavage followed by mass mapping with mass spectrometry. Six refolding intermediates of IGF-I and three refolding intermediates of LR(3)IGF-I were isolated and characterized. Folding pathways of IGF-I and LR(3)IGF-I are proposed based on the time-dependent distribution and disulfide structure of the corresponding trapped intermediates. Similarities and differences in the refolding behavior of IGF-I and LR(3)IGF-I are discussed.

Amino Acid Sequence↗

PubMed1999

Cell elongation induces laminin alpha2 chain expression in mouse embryonic mesenchymal cells: role in visceral myogenesis.

Bronchial smooth muscle (SM) mesenchymal cell precursors change their shape from round to spread/elongated while undergoing differentiation. Here we show that this change in cell shape induces the expression of laminin (LM) alpha2 chain not present in round mesenchymal cells. LM alpha2 expression is reversible and switched on and off by altering the cell's shape in culture. In comparison, the expression of LM beta1 and gamma1 remains unchanged. Functional studies showed that mesenchymal cell spreading and further differentiation into SM are inhibited by an antibody against LM alpha2. Dy/dy mice express very low levels of LM alpha2 and exhibit congenital muscular dystrophy. Lung SM cells isolated from adult dy/dy mice spread defectively and synthesized less SM alpha-actin, desmin, and SM-myosin than controls. These deficiencies were completely corrected by exogenous LM-2. On histological examination, dy/dy mouse airways and gastrointestinal tract had shorter SM cells, and lungs from dy/dy mice contained less SM-specific protein. The intestine, however, showed compensatory hyperplasia, perhaps related to its higher contractile activity. This study therefore demonstrated a novel role for the LM alpha2 chain in SM myogenesis and showed that its decrease in dy/dy mice results in abnormal SM.

Actins↗

PubMed1999

Benzo[k]fluoranthene enhancement and suppression of 17beta-estradiol catabolism in MCF-7 breast cancer cells.

It previously was shown that benzo[k]fluoranthene (BkF), a polycyclic aromatic hydrocarbon frequently detected in environmental samples, increases catabolism of 17beta estradiol (E2) in human breast cancer cells. Data in the present paper demonstrate that BkF both increases and inhibits the catabolism of E2 in MCF-7 breast cancer cells, and that the in vitro BkF increase and inhibition are dependent on the concentration of BkF and the length of the incubation period. A radiometric assay was used to investigate the catabolism of [3H]E2 after exposure to 5 concentrations of BkF for 6, 12, 24, 36, 48, 60, or 72 h. The concentration of BkF necessary for maximal increase in catabolism of E2 varied with the incubation period. At 6 h, a maximal increase was obtained with 0.01 and 0.1 microM, and at 48 h a maximal increase was obtained with 0.5 microM and 1 microM BkF. The increased rate of E2 catabolism was transient at lower concentrations of BkF but remained maximal at 72 h with 0.5 and 1 microM BkF. The highest concentration of BkF tested, 5 microM, was inhibitory at all time points. In contrast to BkF, fluoranthene (FL), another PAH frequently detected in environmental samples, did not significantly increase the catabolism of E2 at any of the concentrations or time points tested. Results showing that BkF inhibits the catabolism of E2 induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) suggest that the BkF inhibition of cellular E2 catabolism is due to competition between BkF and E2 for the TCDD-induced enzymes. Overall, results from these studies demonstrate that BkF both increases and inhibits the cellular catabolism of E2, and emphasize the importance of considering time as well as concentration when conducting short-term in vitro assays.

Breast Neoplasms↗