Search PubMed⌕ Search

Biomedical subjects

M Xie

Publications and source records attributed to M Xie.

87 records · Page 5Linked to original sources
PubMed1993

Glycosylphosphatidylinositol-specific phospholipase D is localized in keratinocytes.

Glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) is abundant in mammalian plasma, but little is known of its cellular and tissue distribution. In this study frozen sections of perfused tissues from adult rats were stained with monoclonal antibodies against GPI-PLD. The most intense staining was observed in the stratified squamous epithelium of the forestomach. Staining was also observed in the esophagus, the tongue, the hard palate, and the skin but not in most other tissues including the columnar epithelium of the stomach or the lower gastrointestinal tract. GPI-PLD expression was also detected in several keratinocyte cell lines. Biochemical assays of glycosylphosphatidylinositol-degrading activity using [3H]myristate-labeled variant surface glycoprotein as substrate provided independent evidence for the presence of GPI-PLD. Expression of GPI-PLD by keratinocytes was not affected by culture in serum-free media, indicating that it does not originate by uptake of serum GPI-PLD in the media. These data suggest that keratinocytes are an important site of action of GPI-PLD and possibly a contributor to the plasma GPI-PLD pool.

Animals↗
PubMed1993

[Studies on the strain differences of Schistosoma japonicum in the mainland of China. XII. DNA hybridization of five isolates].

The nonradioactive labelled probe pSM 889 was hybridized to Southern blots of genomic DNA of five isolates of Schistosoma japonicum from Anhui, Hubei, Guangxi, Sichuan and Yunnan in the mainland of China. The major bands of hybridization of DNA digested by restriction endonucleases EcoRI and BamHI are same among the five isolates, but the minor bands of hybridization of DNA digested by EcoRI show some differences between 4.4-9.6 kb and between 2.3-4.4 kb among the five isolates. The result shows that the five isolates are of some genetic variation. It provides, at molecular level, evidence of the existence of different strains of S. japonicum in the mainland of China.

Animals↗
PubMed1993

[The hypoglycemic effect of AH-9].

AH-9 is an acylhydrazine compound with hypoglycemic effects in normal mice, alloxan-induced diabetic mice and spontaneously diabetic KK mice. In terms of equi-molar doses (0.3 mmol/kg po), AH-9 was found to be more potent than phenfornin and glicalazide (diamicron) in normal mice. Insulin resistance was shown to be improved in spontaneously diabetic KK mice and hydrocortisone-induced insulin resistant mice after treatment with AH-9. The LD 50 of AH-9 given orally to mice was found to be 956 mg/kg (about 18 times its effective dose). Studies on the hypoglycemic mechanism of AH-9 (insulin release, insulin receptor and post-receptor) showed that AH-9 did not influence serum insulin levels in mice. But, in in vivo experiments, AH-9 appeared to promote the capacity and affinity of insulin receptors in mouse liver plasma membranes. AH-9 was also found to antagonize the elevation of blood glucose level and liver glycogen content caused by alanine injection. AH-9 was shown to enhance the conversion of U-14C-glucose to 14CO2 in mouse epididymal fat tissue in vitro. According to the above results, the hypoglycemic action of AH-9 might be due to: 1) increasing the capacity and affinity of insulin receptors; 2) directly enhancing glucose aerobic oxidation; and 3) inhibiting gluconeogenesis.

Animals↗
PubMed1993

[The antioxidant action of AH-9].

AH-9 is a compound with hypoglycemic action. AH-9 was also found to have antioxidant activity. The hemolysis, hemoglobin oxidation and lipid peroxidation of erythrocytes induced by hydrogen peroxide and Fe(++)-induced MDA formation of liver microsomes were inhibited by AH-9, and the activity of SOD and catalase were shown to be increased in normal and alloxan-diabetic mice after treatment with AH-9. The above results indicate that AH-9 might act as a scavenger of superoxide and might be useful for improving the pathophysiological state in diabetes mellitus and its complications.

Animals↗
PubMed1992

Synthesis, characterization, and Ca2+ antagonistic activity of diltiazem metabolites.

Diltiazem is a calcium antagonist widely used in the treatment of angina and hypertension. The contributions of metabolites of diltiazem to the vasorelaxant effects of diltiazem were investigated. The synthesis and spectroscopic characterization of eight major cis-diltiazem metabolites are described. Three of the compounds--N, O-didemethylated metabolite (21), O-demethylated metabolite (22), and diltiazem N-oxide (27)--have been recently reported and have not previously been synthesized. The identities of all eight synthetic metabolites have been verified with samples obtained from human urine using combined LC-MS/MS. The Ca2+ antagonistic activities of diltiazem and its metabolites (except 27) were studied on hamster aorta preparations depolarized with KCl. The order of potencies (IC50 +/- SE, microM) is as follows: diltiazem (0.98 +/- 0.47) greater than 17 (2.46 +/- 0.38) greater than or equal to 23 (3.27 +/- 1.02) greater than 26 (20.2 +/- 10.5) greater than 22 (40.4 +/- 15.4) greater than or equal to 25 (45.5 +/- 18.1) greater than 21 (112.2 +/- 33.2) greater than or equal to 24 (126.7 +/- 24.2). Structure-activity relationships are also discussed.

Animals↗
PubMed1992

Electrophoretic and immunologic characterization of proteins of merozoites of Eimeria acervulina, E. maxima, E. necatrix, and E. tenella.

Merozoites of Eimeria acervulina, Eimeria maxima, Eimeria necatrix, and Eimeria tenella were compared by gel electrophoresis, western-blotting with chicken antiserum, indirect fluorescent antibody reactions, and antiserum neutralization. Merozoites from the 4 species had dissimilar patterns of proteins and antigens in soluble and membrane fractions. Coomassie blue staining of SDS-PAGE gels revealed 16-22 protein bands depending on the species of merozoite but only 3 bands per species in the membrane fractions. Homologous and heterologous antisera recognized 5-12 soluble fraction bands and 3-7 membrane fraction bands on immunoperoxidase-stained western blots, depending on the species. When antisera from infected chickens were used in an indirect fluorescent antibody reaction, the merozoites of E. tenella and E. necatrix had a strong reaction with homologous and heterologous antisera. Merozoites of E. acervulina and E. maxima reacted with homologous antisera but had a weak or no reaction with heterologous antisera. Chicken antiserum against E. tenella had no effect on the viability of E. tenella merozoites when they were inoculated into chicken embryos.

Animals↗
PubMed1991

Developmental capacities of two-cell mouse embryos frozen by three methods.

The following three methods were evaluated in order to obtain a most efficient freezing protocol for the preservation of two-cell mouse embryos: (a) slow cooling and slow thawing in 1.5 M dimethyl sulfoxide, (b) slow cooling and fast thawing in 1.5 M propanediol (PROH), and (c) ultrarapid freezing and fast thawing in either 3.5 M DMSO or 3.0 M PROH. In the slow-cooling procedures (a and b) ice nucleation (seeding) was induced manually or automatically. With method a, only a slight difference, 51.8% for manual and 58.9% for automatic seeding, was observed in survival rates, while the development to blastocysts was significantly affected: 35.4% with manual and less than 10% with automatic induction (P less than 0.001). Method b gave high survival (86.2%) and developmental rates (69.0%) with manual seeding compared with automatic seeding (20.7 and 9.8%, respectively; P less than 0.001). Using protocol c, higher survival and developmental rates were obtained with DMSO (84.8 and 55.9%) than with PROH (39.8 and 19.4%, P less than 0.001). These results demonstrate that inducing nucleation manually is superior to the use of a highly sophisticated autoseeding system and that method b with manual seeding is most effective in preserving the developmental capacity of two-cell mouse embryos after freezing and thawing. There is evidence that this is also true of human embryo cryopreservation.

Animals↗
PubMed1990

Analysis of domoic acid and related compounds by mass spectrometry and gas chromatography/mass spectrometry as N-trifluoroacetyl-O-silyl derivatives.

A method is presented for the analysis of shellfish tissue for domoic acid, a neurotoxic amino acid responsible for cases of amnesic shellfish poisoning. Tissue extracts are first taken through a two-stage solid-phase extraction clean-up, using reversed-phase and strong cation exchange cartridges. A two-stage derivatization, using N-methyl-bis-trifluoroacetamide followed by either N-methyl-tert-butyldimethylsilyltrifluoroacetamide or N, O-bis-trimethylsilyltrifluoroacetamide, is then used to produce an N-trifluoroacetyl-O-silyl derivative which can be analyzed by mass spectrometry with introduction via direct inlet probe, moving-belt liquid chromatograph/mass spectrometer interface, or capillary column gas chromatography. The N-trifluoroacetyl-O-tert-butyldimethylsilyl derivative, which has good stability towards hydrolysis, provides a spectrum well suited to gas chromatography/mass spectrometry (GC/MS) using selected ion recording. GC/MS data for two related compounds, kainic acid and dihydrokainic acid, are also reported. The latter is used as an internal standard for quantification of domoic acid, although the method reported is intended primarily for confirmation of the toxin and related compounds in shellfish tissue.

Chromatography, Gas↗
PubMed1990

[Hepatic proliferation factor of human fetus liver cells].

It was demonstrated in this study that after ultrasonification and centrifugation of human fetus liver cells the supernatant could increase the incorporation of 3H-TdR into DNA of mice liver cells approximately 2.57 times than that of control. This proliferation effect is not species-specific, but has a relationship with supernatant content. The maximal promotion of 3H-TdR into DNA of the guinea-pig liver cells took place when the supernatant protein content was about 0.55 mg/ml. The supernatant can be divided into four components by Ultrogel A6 chromatography and the fourth component is the dominant both in protein content and in proliferation activity. SDS-polyacrylamide gel electrophoresis showed that its molecular weight is about 15,000 dalton.

Animals↗
PubMedDate not supplied

Atmospheric sulfur deposition onto different ecosystems over China.

The regional acid deposition model system (RegADMS) was applied to simulate the air sulfur deposition onto different landuse types over China, in which the dry deposition velocities of SO2 and sulfate aerosol (SO4(2-) were estimated by use of a big leaf resistance analogy model and the wet scavenging coefficients were parameterized in terms of precipitation rate. Investigations show that the annual total sulfur deposition over mainland China is 7.24mt (1 mt = 10(6) ton) , in which dry deposition and wet deposition accounts for 56 and 44%, respectively. The sulfur deposition onto agriculture land, grass land, and forest land is 1.09, 3.6 and 1.41 mt, respectively, which sums 6.1 mt and accounts for 84% of the total sulfur deposition. The modeled sulfur deposition was in agreement with the measurement conducted at farmland in Yingtan, a typical read soil region in Jiangxi province of China, during the period of November 1998--October 1999. The total sulfur deposition at the Yingtan site is about 10.3 gm(-2) year(-1) of which 83% is dry deposition. The modeling sulfur deposition at the same site is 8.4 g m(-2) year(-1) Furthermore, the comparison between RegADMS and RAINS-ASIA on modeling regional sulfur deposition shows the consistence of the two models. The correlation coefficient between the simulated sulfur deposition at the medium-large cities reaches 0.72.

Air Pollutants↗