Biomedical subjects

X D Xie

Publications and source records attributed to X D Xie.

6 recordsLinked to original sources

PubMed2006

Homocysteine accelerates senescence and reduces proliferation of endothelial progenitor cells.

Our previous studies showed that homocysteine (Hcy) reduces endothelial progenitor cell (EPC) numbers and impairs functional activity. However, the mechanisms by which Hcy reduces EPCs numbers and activity remain to be determined. Recent studies have demonstrated that reduced EPCs numbers and activity was associated with EPCs senescence which involved telomerase activity. Therefore, we investigated whether Hcy accelerates the onset of EPCs senescence through telomerase inactivation, leading to cellular dysfunction. EPCs were isolated from peripheral blood and characterized. After ex vivo cultivation, EPCs became senescent as determined by acidic beta-galactosidase staining. Hcy dose-dependently accelerated the onset of EPCs senescence in culture. Moreover, Hcy decreased proliferation of EPCs as assessed by BrdU incorporation assay and colony-forming capacity. To get further insights into the underlying mechanisms of these effects induced by Hcy, we measured telomerase activity and determined the phosphorylation of Akt by using western blot. Hcy significantly diminished telomerase activity and Akt phosphorylation. Taken together, the results of the present study demonstrated that Hcy accelerated the onset of EPCs senescence, leading to cellular dysfunction. The effect of Hcy might be dependent on telomerase inactivation, and Akt dephosphorylation also appeared to play a major role. In addition, atorvastatin had a preventative effect against Hcy-induced EPCs senescence.

Blotting, Western↗

PubMed2004

Effects of homocysteine on number and activity of endothelial progenitor cells from peripheral blood.

The aim of this study is to investigate whether homocysteine (Hcy) has influences on endothelial progenitor cells (EPCs) number and activity. Total mononuclear cells (MNCs) were isolated from peripheral blood by Ficoll density gradient centrifugation, and then the cells were plated on fibronectin-coated culture dishes. After 7 d cultured, attached cells were stimulated with Hcy (to make a series of final concentrations: 10, 50, 100 and 200 micromol/l) or vehicle control for the respective time points (6, 12, 24 and 48 h). EPCs were characterized as adherent cells double positive for DiLDL uptake and lectin binding by direct fluorescent staining under a laser scanning confocal microscope. EPCs proliferation, migration and in vitro vasculogenesis activity were assayed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, modified Boyden chamber assay and in vitro vasculogenesis kit, respectively. EPCs adhesion assay was performed by replating those on fibronectin-coated dishes, and then adherent cells were counted. Incubation of isolated human MNCs with Hcy dose and time dependently decreased the number of EPCs, maximum at 200 micromol/l, 24 h (approximately 50% reduction, P < 0.01). In addition, Hcy dose and time dependently impaired EPC proliferative, migratory, adhesive and in vitro vasculogenesis capacity. In conclusion, hyperHcy may induce the reduction of EPCs with decreased functional activity.

Cell Division↗

PubMed2001

Location and migration of cations in Cu(2+)-adsorbed montmorillonite.

Locations of Cu2+ ion in Cu(2+)-adsorbed montmorillonite have been studied by electron paramagnetic resonance (EPR), supplemented by X-ray diffraction (XRD) and differential thermal analysis (DTA). In the EPR spectra of Cu(2+)-adsorbed montmorillonite, three signals, corresponding to Cu2+ ion, have been simultaneously recorded. Some Cu2+ ions seemed to replace the original interlayer metal cations and some entered into the hexagonal cavities. A small fraction of Cu2+ ions penetrated into the octahedral vacancies. There were two ways for the adsorption of Cu2+ ion by montmorillonite--exchangeable and specific. On heating, the hydrated Cu2+ ion in the interlayer loses the coordinating water and then enters into the hexagonal cavities. When the heating temperature further increased, dehydroxylation occurs, which facilitates Cu2+ ion in the hexagonal cavities to penetrate into the octahedral vacancies.

Adsorption↗

PubMed2001

Tibetan population data on the multiplex short tandem repeat loci--D16S539, D7S820, and D13S317.

The multiplex amplification system of three tetrameric short tandem repeats loci (D16S539, D7S820, and D13S317) have been analysed extensively in various populations for forensic application. Population genetic studies were carried out for these three loci in a population sample of 129 unrelated Tibetan individuals by using a multiplex polymerase chain reaction (PCR) followed by 4% polyacrylamide gel electrophoresis (PAGE) and silver staining. All loci were in accordance with the Hardy-Weinberg expectations. The observed heterozygosities of three loci-D16S539, D7S820, and D13S317 were 73.3%, 81.4% and 80.6%, respectively. The polymorphism information contents (PIC) were 0.84, 0.80 and 0.83, respectively. Comparing with Han population, there was no statistically significant difference except for D16S539 locus.

Chromosome Mapping↗

PubMed1990

Polyanhydrides. V. Branched polyanhydrides.

The objective of the present study was to investigate the properties of branched polyanhydrides and compare them to the corresponding linear polymers. Sebacic acid was polymerized with 1,3,5 benzenetricarboxylic acid and poly(acrylic acid) to yield random and graft-type branched polyanhydrides. The polymerization was followed until the gel point and the resulting polymers were evaluated for their physico-chemical properties and degradation behaviour. Drug release from these polymers was studied using morphine as a model drug. The experiment showed that the molecular weights of branched polyanhydride were significantly higher (mol wt 250,000) than the molecular weight of linear poly(sebacic anhydride) (mol wt 80,000). In the case of poly(acrylic acid) branched polymers, the molecular weight increased linearly with increasing concentration of poly(acrylic acid). The specific viscosities of the branched polyanhydrides were lower than linear polyanhydrides with similar molecular weights. Except for the difference in molecular weights, there were no noticeable changes in the physico-chemical or thermal properties of the branched polymers and the linear poly(sebacic anhydride). The degradation of the branched polyanhydride was triphasic and the degradation rates were faster than for linear poly(sebacic anhydride). The release of morphine from the branched polymers was lower than the corresponding poly(sebacic anhydride). Release of morphine was much higher from the poly(acrylic acid) branched polymers compared to the 1,3,5 benzenetricarboxylic acid branched polymers and increased with increasing concentrations of the branching agent. However, in both cases the release rates and the total amounts of morphine released approached that of poly(sebacic anhydride).

Anhydrides↗

PubMedDate not supplied

Association of ACE, ACE2 and UTS2 polymorphisms with essential hypertension in Han and Dongxiang populations from north-western China.

To assess the significance of polymorphisms of the genes for angiotensin-converting enzyme (ACE), angiotensin-converting enzyme 2 (ACE2) and urotensin II (UTS2) as risk factors for essential hypertension in two populations from north-western China, we enrolled 198 patients with essential hypertension and 131 healthy controls from the Han population and 120 patients with essential hypertension and 102 healthy controls from the Dongxiang population. Polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism were used to analyse gene polymorphisms. The results provided evidence that genetic variants of UTS2 and ACE2 may play a role in the development of essential hypertension in these populations. Polymorphisms of ACE were not associated with essential hypertension in either population. This is the first report showing that the S89N single-nucleotide polymorphism of the UTS2 gene is associated with essential hypertension.

Adult↗