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Biomedical subjects

L X Wang

Publications and source records attributed to L X Wang.

At least 55 records · Page 3Linked to original sources
PubMed1993

[Catheter radiofrequency current ablation of septal atrioventricular accessory pathway in patients with Wolff-Parkinson-White syndrome].

Thirteen patients with Wolff-Parkinson-White syndrome were ablated with radiofrequency current. The thirteen septal atrioventricular accessory pathways in these patients included 4 right anteroseptal, 4 right posteroseptal and 5 left posteroseptal. For patients with right anteroseptal and posteroseptal accessory pathways, a large-tip ablation catheter was advanced via right femoral vein to an area just above the His bundle and around the coronary sinus ostium. For patients with left posteroseptal accessory pathways. An ablation catheter was placed at the left ventricular side of mitral annulus. All of the accessory pathways were abolished successfully. The average current applications was 14 and mean accumulated energy was 18,900 joules. The mean procedure period is 2.3 hours. There were no severe complications and there was no recurrence after 6 months of follow-up. It is shown that radiofrequency current ablation of septal accessory pathways in patients with Wolff-Parkinson-White syndrome is a safe and effective modality of treatment.

Adolescent↗
PubMed1992

Primary structure and disulfide bridge location of arrowhead double-headed proteinase inhibitors.

Two arrowhead proteinase inhibitors (inhibitors A and B) were characterized and their primary structures were determined. Both inhibitors A and B are double-headed and multifunctional protease inhibitors. Inhibitor A inhibits an equimolar amount of trypsin and chymotrypsin simultaneously and weakly inhibits kallikrein. Inhibitor B inhibits two molecules of trypsin simultaneously and inhibits kallikrein more strongly than does inhibitor A. The amino acid sequences of inhibitors A and B were determined by sequencing the reduced and S-carboxamidomethylated proteins and their peptides produced by cyanogen bromide or proteolytic lysylendopeptidase or Staphylococcus aureus V8 protease cleavage. Inhibitors A and B consist of 150 amino acid residues with three disulfide bonds (Cys 43-Cys 89, Cys 110-Cys 119, and Cys 112-Cys 115) and share 90% sequence identity, with 13 different residues. Since the primary structures are totally different from those of all other serine protease inhibitors so far known, these inhibitors might be classified into a new protease inhibitor family.

Amino Acid Sequence↗
PubMed1992

[The effect of Astragalus polysaccharide on endotoxin-induced toxicity in mice].

Astragalus Polysaccharide (APS), an active component, was isolated from the radix of Astragalus membranaceus Bge var. mongholicus (Bge) Hsiao, and the effects of APS on E. coli endotoxin-induced liver damage were investigated in mice. The results showed that when mice were pretreated with APS (30, 60, 100 mg.kg-1.d-1 x 7d, ip), the survival rate of endotoxin intoxicated mice was increased the lowering of ATP levels and adenylate energy charge in mouse liver could be prevented. APS 100 mg.kg-1 could protect the mice from death on endotoxin (25 mg.kg-1) intoxication; and the level of ATP, the value of adenylate energy charge in the protected mouse liver were almost recovered to normal range. The effects of APS were shown to be dose-dependent. Concomitantly, the increase of MDA and decrease of GSH in mouse liver could be corrected by APS pretreatment. The results revealed that APS has an antioxidative action. An ultramicroscopic examination showed that the injury of the bio-membrane and the crest of mitochondria were ameliorated by APS pretreatment. These findings suggest that the protective effects of APS on E. coli endotoxin intoxicated mice may be due to its antioxidative action to protect the mitochondria bio-membrane, therefore, the adenylate metabolism is improved in mouse liver.

Adenosine Triphosphate↗
PubMed1991

Peracetylated laminaribiose: preparation by specific degradation of curdlan and its chemical conversion into N-acetylhyalobiuronic acid.

beta-Laminaribiose octaacetate (2b) was prepared in greater than 50% yield from the microbial polysaccharide curdlan by specific degradation with a yeast cell-wall lytic enzyme preparation, Kitalase,and subsequent acetylation. Acetolysis of curdlan also gave alpha-laminaribiose octaacetate (2a) in 27% yield. The usefulness of these peracetates 2a and 2b as starting materials for organic synthesis was shown by converting 2b into N-acetylhyalobiuronic acid (23), the disaccharide repeating unit of hyaluronic acid. The conversion was carried out via a series of reactions, which included azidonitration of the glucal derivative and selective alkylidenation or direct tritylation to discriminate two primary hydroxyl groups existing in the disaccharide intermediates.

Acetates↗
PubMed1991

Myristic acid utilization and processing in BC3H1 muscle cells.

Because myristic acid (14:0) is important in regulating cell function, we have studied its utilization in BC3H1 muscle cells. Phosphatidylcholine contained 70-80% of the [9,10-3H]14:0 radioactivity incorporated into the cell phospholipids. In both myoblasts and myocytes, however, large amounts of radioactivity also accumulated in a labile neutral lipid pool consisting mostly of triacylglycerol. Therefore, radioactive lipid products formed when BC3H1 cells labeled with 14:0 are stimulated are not necessarily derived only from phosphatidylcholine. Elongation of [9,10-3H]14:0 occurred rapidly in the myoblasts and myocytes, and extensive desaturation also occurred in the myoblasts. Thus, even after short periods of labeling, substantial amounts of radioactivity are contained in fatty acids other than 14:0. The labeling of proteins with [9,10-3H]myristic acid was generally similar in the myoblasts and myocytes. A number of lipid-soluble, polar radioactive metabolites were released into the medium during incubation of [9,10-3H]14:0 with the cells. [1-14C] 14:0 was not converted to these compounds, indicating that they are chain-shortened 14:0 derivatives. Based on chemical analysis, two of the major products appear to be hydroxylated fatty acids. This oxidation process shows some specificity for 14:0 because similar compounds were not produced from palmitic, oleic, or linoleic acids. The myocytes formed larger amounts of the metabolites than the myoblasts, suggesting that differentiation may increase the activity of this 14:0 oxidative pathway.

Acylation↗
PubMed1991

Inhibitory property characterization and reactive site exploration of the arrowhead proteinase inhibitor.

Affinity chromatography was used to separate two components A and B of the crystalline arrowhead proteinase inhibitor. Both A and B are double-headed and multifunctional proteinase inhibitors. Inhibitor A is capable of inhibiting equimolarly trypsin and chymotrypsin simultaneously, and has a weak inhibitory activity toward kallikrein; whereas inhibitor B can inhibit two molecules of trypsin simultaneously, and shows rather higher inhibitory activity toward kallikrein than inhibitor A, but its inhibitory activity toward chymotrypsin is much weaker than that of inhibitor A. The results of chemical modification and the competitive binding of trypsin and chymotrypsin with inhibitor A showed that the two reactive sites of both inhibitors A and B are Lys and Arg residues. Among them the Lys reactive site is specific for inhibiting mainly trypsin, whereas the active domain composed of the Arg reactive site appears to be multifunctional and capable of inhibiting many different Ser proteinases. Based on the structural characteristics of inhibitors A and B, it was predicated that the two reactive sites should be located in the positions Lys-Ser (44-45) and Arg-Tyr-Lys (76-78), respectively. In inhibitor A, there exists another hydrophobic residue involved in inhibiting chymotrypsin. This residue might be situated in the reactive region composed of the Arg reactive site.

Chymotrypsin↗
PubMed1990

Tissue kallikrein-binding protein is a serpin. I. Purification, characterization, and distribution in normotensive and spontaneously hypertensive rats.

Kallikrein-binding protein was purified to apparent homogeneity from rat serum by Affi-Gel Blue, DEAE-Sepharose CL-6B, Sephacryl S-200 chromatography, and preparative gel electrophoresis or high performance liquid chromatography. The purified protein migrates as a single band of 60 kDa in a sodium dodecyl sulfate-polyacrylamide gel under reducing conditions. It is an acidic protein with isoelectric points ranging from 4.2 to 4.6. The amino terminus of the binding protein is an Asp residue as determined by sequence analysis. It forms a 92-kDa sodium dodecyl sulfatestable complex with kallikrein with a t1/2 of 18 min. Western blot and radioimmunoassay showed a distribution of the kallikrein-binding protein in serum, urine, and various tissues with a 5-10-fold lower amount in spontaneously hypertensive rats (SHR) than in Wistar-Kyoto rats (WKY). A full length cDNA clone encoding the kallikrein-binding protein was isolated from a rat liver cDNA library by immunoscreening and the translated amino acid sequence matches the amino-terminal 29-amino acid sequence of the binding protein. The cDNA sequence shares 68.8% identity with human alpha 1-antichymotrypsin and is identical to that of a rat hepatic protein. Dot blot analysis shows that kallikrein-binding protein is expressed at high levels in the liver and at low levels in the lung, salivary gland, and kidney. Its mRNA level in the liver decreases by 2-fold after acute phase inflammation and is higher in male than in female rats. Genomic Southern blot analyses reveal restriction fragment length polymorphisms between SHR and WKY rats in the binding protein locus. The results indicate that rat kallikrein-binding protein belongs to the serpin superfamily and its level is significantly reduced in the spontaneously hypertensive rats.

Amino Acid Sequence↗
PubMed1990

[Influence of septohippocampal lesion on the levels of some neurotransmitters and enzymes in the rat hippocampus].

Partial deafferentation of the hippocampus was obtained by transection of unilateral partial fimbria-fornix. On the seventh postoperational day, there appeared in the lesioned hippocampus respectively a 72.5%, 45.7% and 52.2% reduction in acetylcholine content, choline acetyltransferase and cholinesterase activity. A concomitant 16.3%, 31.1% and 30.3% reduction in noradrenaline, dopamine and serotonin content respectively was also observed, while amino acids content did not show any change. The results indicate that the cholinergic and monoaminergic afferents of the hippocampal formation in the rat reach their target regions via the fimbria-fornix.

Acetylcholine↗
PubMed1990

Localization of 12-hydroxyeicosatetraenoic acid in endothelial cells.

Bovine aortic endothelial cells take up 12-hydroxyeicosatetraenoic acid (12-HETE), a lipoxygenase product formed from arachidonic acid. The uptake of [3H]12-HETE reached a maximum in 2 to 4 h. At this time, from 75 to 80% of the incorporated radioactivity was contained in phospholipids, about 85% of the esterified radioactivity remained in the form of 12-HETE, and at least 90% of the phospholipid radioactivity was present in the sn-2-position. Subcellular fractionation on Percoll and sucrose gradients demonstrated that 65 to 74% of the radioactivity was present in membranes enriched in NADPH-cytochrome c reductase and UDP-galactosyl transferase. The specific radioactivity relative to protein of these intracellular membranes was 2.9-times higher than in a plasma membrane fraction enriched in 5'-nucleotidase. A similar intracellular localization was observed when [3H]5-HETE or [3H]arachidonic acid were taken up. The 12-HETE was contained primarily in the choline glycerophospholipids of the microsomal membranes. After incorporation, [3H]12-HETE was removed from the cell lipids much more rapidly than [3H]arachidonic acid, and 80% of the radioactivity released into the medium during the first hour remained as 12-HETE. Because it accumulates in microsomal membranes, 12-HETE uptake may perturb certain intracellular processes and thereby lead to endothelial dysfunction. The relatively rapid removal of the newly incorporated 12-HETE may be an important protective mechanism that prevents excessive accumulation and more extensive endothelial damage.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1989

Sequential observation of clinical and karyotypic evolution in a patient with myelodysplastic syndrome.

This paper reports an interesting case of myelodysplastic syndrome (MDS), whose bone marrow karyotype at diagnosis was 46, XY, t(16;17) (q12;q25). Fourteen months later, the disease transformed into erythroleukemia, and several correlative clones with hyperdiploid appeared at the same time. Thus, we consider that detecting karyotypic evolution may help evaluate the prognosis of MDS.

Anemia, Refractory↗
PubMed1986

Effect of cortisol on luteinizing hormone release during sexual behavior in the boar.

The effect of inhibiting the rise in cortisol concentrations that occurs at copulation upon luteinizing hormone release was studied in seven adult boars. Plasma samples were collected for assay of luteinizing hormone, testosterone and cortisol on a control day and before, during and after exposure to an estrous sow. The area under the curve was used to evaluate hormone production and treatment effects were evaluated by a paired Student's t-test. The 11 beta-hydroxylase inhibitor, metyrapone, was used to suppress glucocorticoid hormone production. Cortisol concentrations increased significantly (p less than 0.05) after breeding compared to values on the control day while treatment with metyrapone prior to breeding prevented the cortisol increase (p greater than 0.05). Although luteinizing hormone production increased significantly after copulation in both breeding experiments, metyrapone pretreatment resulted in a reduction of luteinizing hormone secretion (p less than 0.05). Testosterone production was also reduced in boars pretreated with metyrapone. The results suggest that the increased levels of cortisol occurring at copulation may enhance luteinizing hormone release in boars.

Animals↗
PubMed1985

The complete amino-acid sequence of the proteinase inhibitor B from the root of the arrowhead (Sagittaria sagittifolia L.).

After reduction and alkylation of the disulfide bonds of the proteinase inhibitor B from the root of the arrowhead (Sagittaria sagittifolia L.) followed by CNBr cleavage three peptide fragments with 68, 62 and 11 amino-acid residues could be separated on DEAE-Sepharose CL-6B. The peptides or the inhibitor itself were further specifically cleaved either by trypsin or by the mixture of (CH3)2SO/HCl/HBr at the arginyl- and the tryptophyl-peptide bond, respectively. The complete amino-acid sequences of the peptides were determined by manual solid phase DABITC/PITC double coupling micro-method and the primary structure of the arrowhead inhibitor B consisting of 141 amino-acid residues was then elucidated. Twenty pairs of amino-acid residues are repeated in the molecule of this inhibitor, three of these pairs even occur three times. The possible locations of the reactive sites are discussed. On the basis of sequence comparisons between this inhibitor and all other serine proteinase inhibitors the arrowhead inhibitor may belong to a new family.

Amino Acid Sequence↗
PubMed1984

Studies on the mung bean trypsin inhibitor--reduction and reoxidation of the disulfide bonds of the Lys active fragment.

Two peptide chains A1 and A2 of the Lys active fragment, linked via a couple of inter-disulfide bonds, could be separated from each other after reduction with dithiothreitol and gel filtration on Sephadex G-25. Reoxidation of the reduced peptide chain A1 resulted in recovering the inhibitory activity with 25% yield, based on the original activity of the Lys fragment. The A1 active fragment was further purified by affinity chromatography with immobilized trypsin. Sephadex G-25 gel filtration produced two forms of the A1 active fragment, the major fraction being a monomer and the minor one being a dimer with lower activity. The results obtained offered evidence of the evolution of mung bean inhibitor from an ancestral single-headed inhibitor by fused gene duplication with A2 as a connecting peptide. The CD spectra of the Lys fragment and the reoxidized peptide chain A1 were also compared.

Amino Acids↗