Search PubMed⌕ Search

Biomedical subjects

X Shi

Publications and source records attributed to X Shi.

At least 235 records · Page 13Linked to original sources
PubMed1999

[Study on qualitative analysis method of high performance liquid chromatography by simultaneous multi-wavelength detection].

In this paper, we introduce an HPLC qualitative method, that is, multiwavelength detection qualitative analysis method. According to Beer's law, for a certain compounds the ratio of peak areas at different wavelengths is a constant. Comparing the ratio of peak areas of a component at different wavelengths with that of the standard by means of simultaneous multi-wavelength detection, we established a convenient qualitative method. This method has been applied successfully to qualitative analysis of 18 aromatic amines in the prohibited azo dyes.

Benzidines↗
PubMed1999

[A primary clinical study of HRV analysis of nonlinear dynamics].

We observed the changes of nonlinear dynamic parameters in the patients with diabetes and old myocardial infarction with the methods of nonlinear dynamics. The results indicate that the correlation dimension of the patients with old myocardial infarction is higher than that of the normal, their Lyapunov exponent is lower than the normal's; that the correlation dimension of the patients with diabetes is also higher than that of the normal, their Lyapunov exponent is lower than the normal's; and that the values of the entropy of the two patient groups are basically identical to the entropy of the normal. Therefore the correlation dimension can indicate the changes in the function of autonomic nerve of the patients with diabetes and old myocardial infarction.

Autonomic Nervous System↗
PubMed1999

[Analysis of acidic and cationic dyes by thin layer chromatography].

This paper describes the selection of solvent system of thin layer chromatography(TLC) by method of the correlation coefficient for the separation of acidic and cationic dyes. The acidic and cationic dye mixture was extracted from the same coloured wool fiber and acrylic fiber samples. The two solvent systems with smallest correlation coefficients could offer more informations for the identification of the dyes. The method is simple, accurate, effective and can be applied to examine dyes on the textile by selection of TLC solvent system in the forensic science laboratories.

English Abstract↗
PubMed1999

[Primary study on HRV analysis of nonlinear dynamics in animal experiment].

The purpose of this study was to address the relationship between the parameters of nonlinear dynamics and functions of heart. We adopted the methods of nonlinear dynamics in observing the changes of the parameters of nonlinear dynamics under the conditions that sympathetic or parasympathetic nerve of heart exists singly as well as the coronary artery is narrowed. The results showed that in case the sympathetic or parasympathetic nerve was cut off the correlation dimension and entropy were lower than the normals, and in case the coronary artery was seriously narrowed the correlation dimension, entropy and laypunav exponent were also lower than the normals. The conclusion is that the parameters of nolinear dynamics can indicate the changes of the functions of autonomic nerve under the above conditions.

Animals↗
PubMed1999

[The inhibitory effect of selenite and other antioxidants on the complement mediated experimental pulmonary alveolitis].

OBJECTIVE: To test the regulatory effect of selenite and other antioxidants on complement PMN activation feedback mechanism mediated inflammatory response in experimantal pulmonary vasculitis. METHODS: Mouse model of pulmonary Arthus reaction vasculitis developed with BSA sensitization and antigen inhalation was used for tests of inhibitory effect of oral administration of sodium selenite, glycyrrhizin flavonoids and/or vitamin E on the incidence of developing vasculitis, which could reflect the modulation of inflammatory response and tissue injury. RESULTS: A remarkable inhibitory effect of selenite or combined flavonoid and vitamin E on the induction of pulmonary vasculitis were observed as the incidence of vasculitis could drop from 100% of the untreated group down to 25% of the antioxidants treated groups, revealing modulation of inflammatory response. CONCLUSIONS: It indicated a newer insight into mechanism of the inflammatory response could give a novel approach to the modulation of inflammatory response. An adjuvant therapy of selenium and antioxidants to the interventions of inflammatory disorders has been expected.

Animals↗
PubMed1999

Effects of pirfenidone on the generation of reactive oxygen species in vitro.

Pirfenidone is a newly developed antifibrotic drug that has been reported to retard the progression of pulmonary fibrosis induced by bleomycin and cyclophosphamide in animal models of lung fibrosis. The present in vitro studies using noncellular and cellular systems evaluated the antioxidant and cytotoxic properties of this drug. The Fenton reaction [Fe(II) + H2O2 --> Fe(III) + *OH + OH-] and the xanthine/xanthine oxidase system were used as sources of hydroxyl (*OH) and superoxide anion (O2*-) radicals, respectively. Electron spin resonance spin trapping was used for free radical detection and measurement. The reaction rate of pirfenidone with *OH was found to be 1.63 x 10(10) M(-1) s(-1), which is comparable to several well-established antioxidants, such as ascorbate, glutathione, cysteine, azide, and lipoic acid. Compared to *OH radicals, the O2*- scavenging was less efficient 42.36 M(-1) s(-1) with pirfenidone. Pirfenidone was also effective in inhibiting zymosan-stimulated chemiluminescence. In a noncellular model of lipid peroxidation, pirfenidone inhibited crystalline silica-induced lipid peroxidation. The inhibition of crystalline silica-induced cytotoxic reactions and lipid peroxidation combined with the efficient antioxidant properties of pirfenidone indicate that this agent may express its antifibrotic effects partly through its ability to scavenge reactive oxygen species.

Animals↗
PubMed1999

New insights into the role of nuclear factor-kappaB, a ubiquitous transcription factor in the initiation of diseases.

Nuclear factor-kappaB (NF-kappaB) is a ubiquitous transcription factor that governs the expression of genes encoding cytokines, chemokines, growth factors, cell adhesion molecules, and some acute phase proteins in health and in various disease states. NF-kappaB is activated by several agents, including cytokines, oxidant free radicals, inhaled particles, ultraviolet irradiation, and bacterial or viral products. Inappropriate activation of NF-kappaB has been linked to inflammatory events associated with autoimmune arthritis, asthma, septic shock, lung fibrosis, glomerulonephritis, atherosclerosis, and AIDS. In contrast, complete and persistent inhibition of NF-kappaB has been linked directly to apoptosis, inappropriate immune cell development, and delayed cell growth. Therefore, development of modulatory strategies targeting this transcription factor may provide a novel therapeutic tool for the treatment or prevention of various diseases.

Animals↗
PubMed1998

New generation dopaminergic agents. 5. Heterocyclic bioisosteres that exploit the 3-OH-N1-phenylpiperazine dopaminergic template.

The synthesis of several bioisosteric analogs based on the 3-OH-N1-phenylpiperazine dopamine D2 agonist template (i.e., 4) is described. The indolone (5) and 2-CF3-benzimidazole (13) were observed to have excellent affinity for the D2 receptor. Several D4 selective compounds were also identified. Molecular modeling studies and a putative bioactive conformation are discussed.

Animals↗
PubMed1998

Evidence that the RNA methylation and poly(A) polymerase stimulatory activities of vaccinia virus protein VP39 do not impinge upon one another.

Vaccinia protein VP39 has two RNA modifying activities. In monomeric form, it acts as an mRNA cap-specific 2'-O-methyltransferase, specifically modifying the ribose moiety of the first transcribed nucleotide of m7G-capped mRNA. In association with VP55, the catalytic subunit of the vaccinia poly(A) polymerase, VP39 facilitates the rapid elongation of poly(A) tails that are already greater than approximately 35 nt in length. Introducing new assays, we provide evidence that substrates for each of VP39's two activities do not detectably modulate the converse reaction and that VP39's 2'-O-methyltransferase activity is not significantly affected by its association with VP55. In an electrophoretic mobility shift assay, VP39 interacted with a short (5 nucleotide) RNA only when the latter was m7G-capped. Complexes with longer (22 nucleotide) RNAs were more stable (i.e., cap-independent) but were further stabilized by the presence of an m7G cap. An additional complex was observed at elevated RNA:protein molar ratios, indicating the presence of two RNA binding sites per VP39 molecule. Interaction at one of these sites was stabilized by the cap structure. Additional experiments indicated that RNA molecules undergoing poly(A) tail elongation by the VP55-VP39 heterodimer are not favored as cap-methylation substrates.

Binding Sites↗
PubMed1998

Antioxidant activity of lazaroid (U-75412E) and its protective effects against crystalline silica-induced cytotoxicity.

Lazaroids (21-amino steroids) are believed to be powerful scavengers of reactive oxygen species (ROS) and inhibitors of lipid peroxidation. Crystalline silica, a potent cytotoxic agent, causes pulmonary fibrosis in experimental animals and humans. ROS have been previously shown to be involved in crystalline silica-induced pulmonary injury and inflammation. In the present study, the reaction rate of lazaroid (U-75412E) with hydroxyl radical (.OH) generated by Fenton reaction (Fe(II) + H2O2 --> Fe(III) + OH- + .OH) was investigated using ESR spin-trapping competition reactions. The reaction rate constant was found to be 1.0 x 10(10) M(-1)s(-1), which was comparable with those of other efficient .OH radical scavengers. As indicators of crystalline silica-induced cytotoxicity and its protection by this antioxidant lazaroid (U-75412E) we measured lactate dehydrogenase, N-acetyl-beta-glucosaminidase, superoxide dismutase, glutathione peroxidase, and hydrogen peroxide released from rat alveolar macrophages. Lipid peroxidation, a prominent manifestation of .OH radical-induced cell injury, was also measured to evaluate the protective value of lazaroid. Alveolar macrophages treated with lazaroid (U-75412E) before crystalline silica exposure were protected against cell injury and lipid peroxidation as demonstrated by those indicators. Lazaroid (U-75412E) scavenges .OH radicals generated by crystalline silica-mediated reaction from H2O2 and inhibits lipid peroxidation in macrophages induced by these particles.

Animals↗
PubMed1998

Lack of correlation of skin thickness with bone density in patients receiving chronic glucocorticoid.

The objective was to test the hypothesis that there is a correlation between thinning of the skin and bone in patients on chronic oral glucocorticoids (GCs). This was a one-time cross-sectional analysis performed in an academic referral center. The study group consisted of 14 patients on GCs for a variety of disorders, including dermatomyositis, pemphigus vulgaris, pyoderma gangrenosum, and urticarial vasculitis. Skin thickness was compared with that of 24 sex- and age-matched controls. The main outcome measures were the bone density of the lumbar spine (L2-L4) and the skin thickness. The skin thickness (mm, mean +/- SEM) in GC-treated (n = 7) vs unmedicated age-matched Caucasian women (n = 20) was 0.84 +/- 0.04 vs 1.02 +/- 0.04 (t = 3.07, P < 0.01) in the upper arm, 1.13 +/- 0.09 vs 1.49 +/- 0.05 (t = 3.65, P < 0.002) in the dorsal forearm, and 0.96 +/- 0.07 vs 1.17 +/- 0.02 (t = 2.92, P < 0.01) in the ventral forearm. L2-L4 bone densities averaged 106 +/- 2% in the GC-treated female patients relative to the age and sex-matched controls. There was no correlation between skin thickness and bone density. In GC-treated (n = 4) vs unmedicated Caucasian men matched for age (n = 4), skin thickness was 1.09 +/- 0.4 vs 1.33 +/- 0.05 (t = 3.51, P < 0.02) in the upper arm, but was not significantly different at the two forearm sites. No correlation between skin thickness and bone density was observed. The level of type I procollagen mRNA in skin from three GC-treated patients was 45% of the value in three age-matched controls. In conclusion, GCs cause statistically significant thinning of skin independently of the effects on bone.

Absorptiometry, Photon↗
PubMed1998

Cobalt-mediated generation of reactive oxygen species and its possible mechanism.

Electron spin resonance spin trapping was utilized to investigate free radical generation from cobalt (Co) mediated reactions using 5,5-dimethyl-1-pyrroline (DMPO) as a spin trap. A mixture of Co with water in the presence of DMPO generated 5,5-dimethylpyrroline-(2)-oxy(1) DMPOX, indicating the production of strong oxidants. Addition of superoxide dismutase (SOD) to the mixture produced hydroxyl radical (.OH). Catalase eliminated the generation of this radical and metal chelators, such as desferoxamine, diethylenetriaminepentaacetic acid or 1,10-phenanthroline, decreased it. Addition of Fe(II) resulted in a several fold increase in the .OH generation. UV and O2 consumption measurements showed that the reaction of Co with water consumed molecular oxygen and generated Co(II). Since reaction of Co(II) with H2O2 did not generate any significant amount of .OH radicals, a Co(I) mediated Fenton-like reaction [Co(I) + H2O2-->Co(II) + .OH + OH-] seems responsible for .OH generation. H2O2 is produced from O2.- via dismutation, O2.- is produced by one-electron reduction of molecular oxygen catalyzed by Co. Chelation of Co(II) by biological chelators, such as glutathione or beta-ananyl-3-methyl-L-histidine alters, its oxidation-reduction potential and makes Co(II) capable of generating .OH via a Co(II)-mediated Fenton-like reaction [Co(II) + H2O2-->Co(III) + .OH + OH-]. Thus, the reaction of Co with water, especially in the presence of biological chelators, glutathione, glycylglycylhistidine and beta-ananyl-3-methyl-L-histidine, is capable of generating a whole spectrum of reactive oxygen species, which may be responsible for Co-induced cell injury.

Catalase↗
PubMed1998

Nucleotide sequence and phylogenetic analysis of the medium (M) genomic RNA segments of three hantaviruses isolated in China.

The medium (M) genome segment of hantaviruses (family Bunyaviridae) encodes the two virion glycoproteins. G1 and G2, as a precursor protein in the complementary sense RNA. We determined the nucleotide sequences of the M genome segments of three Chinese hantavirus isolates, a Hantaan-type (HTN) virus designated A9 and two Seoul-type (SEO) viruses designated L99 and HB55, and compared them to those of other HTN or SEO viruses isolated in Eastern Asia. The M segment of A9 is 3616 nucleotides in length and shows 99.5% identity at the nucleotide level and 99.1% identity at the amino acid level to that of the Chinese HTN isolate HV114. The M segments of L99 and HB55 are 3652 nucleotides in length, one nucleotide longer than the M segments of other sequenced SEO isolates such as SEO 80-39, SR-11, and Biken-1. The Chinese SEO isolates showed 95% nucleotide sequence identity and 99% amino acid sequence identity to SEO 80-39. We also sequenced a 736 nucleotides region of the M genome segment of another Chinese SEO isolate, R22, which revealed errors in the published data. Phylogenetic analysis of the available sequences indicated that both the Chinese HTN- and SEO-type viruses form lineages distinct from those of the isolates from other parts of Eastern Asia.

Amino Acid Sequence↗
PubMed1998

Amino acid sequence of a Ca(2+)-transporting ATPase from the sarcoplasmic reticulum of the cross-striated part of the adductor muscle of the deep sea scallop: comparison to serca enzymes of other animals.

The RT PCR approach was used to obtain the nucleotide sequence of the mRNA of a sarco/endoplasmic reticulum calcium transporting ATPase (SERCA) from the cross-striated (phasic) part of the adductor muscle of the deep sea scallop. Initially, degenerate primers based on consensus sequences among SERCAs and tryptic fragments of the scallop Ca-ATPase were used. The sequence was then extended using homologous primers and the 5' and 3' ends of the transcript determined by 5' and 3' RACE. The mRNA codes for a polypeptide chain 994 amino acid residues long (coded for by 2982 nucleotides) and has a 195 bp 5' untranslated region, with a 697 bp 3' untranslated region. The scallop enzyme shows strongest amino acid similarity to the SERCA enzyme of Loligo, followed by those of Drosophila and Artemia. It resembles the vertebrate SERCA3 in that it does not possess the phospholamban binding motif and so is unlikely to be regulated by protein kinase A mediated signals.

Amino Acid Sequence↗
PubMed1998

Overexpression of E2F-1 in glioma triggers apoptosis and suppresses tumor growth in vitro and in vivo.

The transfer of apoptosis genes to tumors is one of the most promising strategies for cancer gene therapy. We have shown that massive apoptosis occurs when wild-type p53 expression is induced in glioma cells carrying a p53 gene mutation. However, adenovirus-mediated p53 gene transfer is ineffective in causing apoptosis in glioma cells that retain a wild-type p53 genotype. We evaluated the effect of E2F-1 overexpression on the growth of gliomas in vitro and in vivo. In the in vitro study, the adenovirus-mediated transfer of exogenous E2F-1 protein precipitated generalized apoptosis in gliomas. The treatment with Ad5CMV-E2F-1 of nude mice carrying subcutaneous gliomas arrested tumor growth. Our results indicate that E2F-1 has anti-glioma activity in vitro and in vivo.

Adenoviruses, Human↗
PubMed1998

Cardiovascular function following reduced aerobic activity.

PURPOSE: The aim of this study was to test the hypothesis that a sustained reduction of physical activity (deconditioning) would alter the cardiovascular regulatory function. METHODS: Nineteen young, healthy volunteers participated in physical deconditioning for a period of 8 wk. Before (pre) and following (post) physical deconditioning, the responses of heart rate (HR), mean arterial pressure (MAP, measured by Finapres), central venous pressure (CVP), stroke volume (SV, Doppler), and forearm blood flow (FBF, plethysmography) were determined during lower body negative pressure (LBNP). The carotid baroreflex (CBR) function was assessed using a train of pulsatile neck pressure (NP) and suction, and the aortic baroreflex control of HR was assessed during steady-state phenylephrine (PE) infusion superimposed by LBNP and NP to counteract the PE increased CVP and carotid sinus pressure, respectively. RESULTS: Active physical deconditioning significantly decreased maximal oxygen uptake (-7%) and LBNP tolerance (-13%) without a change in baseline hemodynamics. Plasma volume (-3% at P = 0.135), determined by Evans Blue dilution, and blood volume (-4% at P = 0.107) were not significantly altered. During LBNP -20 to -50 torr, there was a significantly greater drop of SV per unit decrease in CVP in the post- (14.7 +/- 1.6%/mm Hg) than predeconditioning (11.2 +/- 0.7%/mm Hg) test accompanied by a greater tachycardia. Deconditioning increased the aortic baroreflex sensitivity (pre vs post: -0.61 +/- 0.12 vs -0.84 +/- 0.14 bpm.mm-1 Hg, P = 0.009) and the slope of forearm vascular resistance (calculated from [MAP-CVP]/FBF) to CVP (-2.75 +/- 0.26 vs -4.94 +/- 0.97 PRU/mm Hg, P = 0.086). However, neither the CBR-HR (-0.28 +/- 0.03 VS -0.39 +/- 0.10 bpm.mm-1 Hg) nor the CBR-MAP (-0.37 +/- 0.16 vs -0.25 +/- 0.07 mm Hg/mm Hg) gains were statistically different between pre- and postdeconditioning. CONCLUSIONS: We concluded that the functional modification of the cardiac pressure-volume relationship resulted in the reduced LBNP tolerance, despite the accentuated aortic and cardiopulmonary baroreflex function following deconditioning.

Adult↗