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Biomedical subjects

X Q Zhang

Publications and source records attributed to X Q Zhang.

At least 19 recordsLinked to original sources
PubMed2003

Differential regulation of beta-arrestin 1 and beta-arrestin 2 gene expression in rat brain by morphine.

Beta-arrestins are a family of regulatory and scaffold proteins functioning in signal transduction of G protein-coupled receptors including opioid receptors. Upon agonist stimulation, beta-arrestins bind to opioid receptors phosphorylated by G protein-coupled receptor kinases and promote receptor internalization and desensitization. Studies indicated that beta-arrestins are required in the development of morphine tolerance in mice. In the current study, we investigated the potential regulatory effects of morphine administration on beta-arrestin 1 and beta-arrestin 2 mRNA levels in different brain regions in rat using in situ hybridization method. Our results showed that the acute morphine administration (10 mg/kg) resulted in approximately 30% reduction in both beta-arrestin 1 and beta-arrestin 2 mRNA levels in hippocampus while the chronic morphine treatment (10 mg/kg, b.i.d., for 9 days) caused no significant change in level of either beta-arrestin mRNA. In locus coeruleus, both acute and chronic morphine treatments resulted in significant decreases (over 50%) in beta-arrestin 1 mRNA level but failed to induce any change in the level of beta-arrestin 2 gene expression. The acute morphine administration had no significant effect on beta-arrestin 1 or beta-arrestin 2 mRNA level in periaqueductal gray and cerebral cortex. However, after chronic morphine treatment, beta-arrestin 2 mRNA level decreased by 40% in periaqueductal gray and increased by 25% in cerebral cortex, in strong contrast to the unchanged beta-arrestin 1 mRNA level in these two brain regions. Furthermore, spontaneous or naloxone-precipitated withdrawal of morphine that did not affect the level of beta-arrestin 1 mRNA resulted in an aberrant increase (100% over control) in beta-arrestin 2 mRNA level in hippocampus. Our results thus demonstrated for the first time that opiate administration regulates level of beta-arrestin mRNAs in brain and the expression of beta-arrestin 1 and beta-arrestin 2 subtypes is differentially regulated in locus coeruleus, periaqueductal gray, and cerebral cortex by morphine. These data suggest that beta-arrestin 1 and beta-arrestin 2 may play different roles in the development of opioid tolerance and dependence.

Animals↗
PubMed2003

Identification of a locus for porokeratosis palmaris et plantaris disseminata to a 6.9-cM region at chromosome 12q24.1-24.2.

BACKGROUND: Porokeratosis palmaris et plantaris disseminata (PPPD) is a rare autosomal dominant dyskeratotic disorder characterized by a cornoid lamella with parakeratosis, hyperkeratosis and loss of granular layers. The genetic basis of this disease is still unknown. Two loci for disseminated superficial actinic porokeratosis (DSAP) were found to be located on 12q23.2-24.1 and 15q25.1-26.1. Both PPPD and DSAP are disseminated types of porokeratosis. OBJECTIVES: To locate the locus for PPPD, thereby facilitating the identification of this disease gene and leading to an understanding of the pathogenesis of porokeratosis. METHODS: Genotyping was performed in a Chinese family with PPPD using polymorphic microsatellite markers on 12q and 15q. RESULTS: The locus for PPPD is located within a 6.9-cM region between markers D12S1613 and D12S1341, with a maximum two-point LOD score of 8.14 (theta = 0.00) at D12S1335. CONCLUSIONS: This study provides a map location for isolation of a gene causing PPPD.

Adolescent↗
PubMed2003

A new glycine substitution mutation in the COL7A1 gene in a Chinese family with dominant dystrophic epidermolysis bullosa.

Dystrophic epidermolysis bullosa (DEB) is caused by mutations in the COL7A1 gene encoding type VII collagen, the major component of anchoring fibrils. The characteristic genetic lesion in dominant DEB (DDEB) is a glycine substitution in the collagenous domain of the protein. In this study, we identified a Chinese family with a four-generation pedigree of DDEB, in whom a novel glycine substitution mutation in COL7A1 was demonstrated. A heterozygous nucleotide G-->A transition at position 6208 in exon 74 of COL7A1 was detected, which resulted in a glycine to arginine substitution (G2070R) in the triple-helical domain of type VII collagen. This substitution was not found in 110 unrelated normal alleles. This report emphasizes the predominance of glycine substitution mutations in DDEB and contributes to the expanding database on COL7A1 mutations.

Adolescent↗
PubMed2003

Fouling and cleaning of microfiltration membrane in municipal wastewater reclamation.

This paper presents an investigation on fouling and cleaning of a tubular microfiltration membrane for municipal wastewater reclamation. A bi-level complex model, namely channel clogging and pore plugging, was introduced to elucidate the fouling mechanism. Based on 135 days of microfiltration of activated sludge, a preventive method for channel clogging was reasonably proposed and proven to be effective. Without channel clogging, the operation period was observed a five-fold increase on average, reaching 3-4 weeks. To remove pore plugging, a multi-step chemical cleaning was employed and further optimized in terms of temperature and alkaline concentration. Generally, the chemical cleaning could restore the membrane permeability to higher than 90%.

Biofilms↗
PubMed2001

Stromal cells expressing ephrin-B2 promote the growth and sprouting of ephrin-B2(+) endothelial cells.

Ephrin-B2 is a transmembrane ligand that is specifically expressed on arterial endothelial cells (ECs) and surrounding cells and interacts with multiple EphB class receptors. Conversely, EphB4, a specific receptor for ephrin-B2, is expressed on venous ECs, and both ephrin-B2 and EphB4 play essential roles in vascular development. The bidirectional signals between EphB4 and ephrin-B2 are thought to be specific for the interaction between arteries and veins and to regulate cell mixing and the making of particular boundaries. However, the molecular mechanism during vasculogenesis and angiogenesis remains unclear. Manipulative functional studies were performed on these proteins in an endothelial cell system. Using in vitro stromal cells (OP9 cells) and a paraaortic splanchnopleura (P-Sp) coculture system, these studies found that the stromal cells expressing ephrin-B2 promoted vascular network formation and ephrin-B2(+) EC proliferation and that they also induced the recruitment and proliferation of alpha-smooth muscle actin (alpha-SMA)-positive cells. Stromal cells expressing EphB4 inhibited vascular network formation, ephrin-B2(+) EC proliferation, and alpha-SMA(+) cell recruitment and proliferation. Thus, these data suggest that ephrin-B2 and EphB4 mediate reciprocal interactions between arterial and venous ECs and surrounding cells to form each characteristic vessel. (Blood. 2001;98:1028-1037)

Animals↗
PubMed2001

Protein kinase C pathway is involved in regulating the secretion of prostatic acid phosphatase in human prostate cancer cells.

The stimulated secretion of prostatic acid phosphatase (PAcP) has been known to be a hallmark of androgen action on human prostate epithelial cells for the last five decades. The molecular mechanism of androgen action on PAcP secretion, however, has remained mostly unknown. We investigated the molecular mechanism that promotes PAcP secretion in LNCaP human prostate carcinoma cells which express PAcP and are androgen-responsive. Treatment with 12-o-tetradecanoyl phorbol-13-acetate (TPA), a protein kinase C (PKC) activator, resulted in an increased secretion of PAcP in a dose- and time-dependent fashion. 4Alpha-phorbol, a biologically inactive isomer of TPA, had no effect. This TPA stimulation of PAcP secretion was observed 2 h after exposure, while TPA did not have a significant effect on the mRNA level even with a 6 h treatment. A23187 calcium ionophore, known to mobilize cellular calcium which is a co-factor of PKC, also activated PAcP secretion. This TPA stimulation of PAcP secretion was more potent than the conventional stimulating agent 5alpha-dihydrotestosterone (DHT) at the same concentration of 50 nM. Furthermore, the action of TPA and DHT on PAcP secretion was blocked by five different PKC inhibitors. Results also showed that DHT, as well as TPA, could rapidly modulate PKC activity. Therefore, PKC can regulate PAcP secretion, and may also be involved in DHT action on PAcP secretion.

Acid Phosphatase↗
PubMed2001

A stable glucose biosensor prepared by co-immobilizing glucose oxidase into poly(p-chlorophenol) at a platinum electrode.

An amperometric glucose biosensor was successfully developed by electrochemical polymerization of p-chlorophenol (4-CP) at a Pt electrode in the presence of glucose oxidase. The amperometric response of this biosensor to hydrogen peroxide, formed as the product of enzymatic reaction, was measured at a potential of 0.6 V (vs. SCE) in phosphate buffer solution. The performances of sensors, prepared at different monomer concentrations and polymerization potentials, were investigated in detail. The biosensor prepared under optimal conditions had a linear response to glucose ranging from 2.5 x 10(-4) to 1.5 x 10(-2) mol L(-1) with a correlation coefficient of 0.997 and a response time of less than 2 s. Substrate selectivity of the polymer-based enzyme electrode was tested for coexisting interferents such as uric acid and ascorbic acid, and no discernible response was observed. After 90 days, the response of the biosensor remained almost unchanged, indicating very good stability.

Biosensing Techniques↗
PubMed2001

Nested genetic algorithm for resolving overlapping spectra.

A nested genetic algorithm, including a genetic parameter level and a genetic implemented level, has been proposed and applied for resolving simulated overlapping spectra. Parameters of genetic algorithms (GA) were optimized by use of the genetic parameter level. The number of overlapping peaks was, moreover, detected simultaneously. Parameters of individual peaks in multiplets were computed by use of the genetic implemented level. It is obvious that the parameters of GA can be optimized and the number of overlapping peaks can be detected by itself. The optimization results are less affected than in traditional curve-fitting by the initial values of the parameters of the overlapping bands. Consequently, the nested genetic algorithm is superior to the curve-fitting technique for resolution of overlapping peaks.

Algorithms↗
PubMed2001

Effects of nitrovasodilators on the human fetal-placental circulation in vitro.

This study examines the vasorelaxation of isolated human placental chorionic plate arteries and the perfused fetal-placental vasculature, in vitro, to a variety of nitrovasodilator compounds including glyceryl trinitrate (GTN) sodium nitroprusside (SNP), S-nitroso-N-acetylpenicillamine (SNAP), S-nitroso-N-glutathione (SNG) and NaNO(2). The effects of these compounds were also examined under conditions of high (>450 mmHg) and low oxygen (<50 mmHg) tension. In a separate series of experiments the effects of GTN and NaNO(2)were further investigated with addition of the antioxidants cysteine (100 microm), glutathione (100 microm) or superoxide dismutase (SOD) (30 I.U./ml). The order of nitrovasodilator potency, when added directly to isolated fetal vessels was GTN=SNP>SNAP=SNG>NaNO(2). The order under low oxygen tension was similar, GTN=SNP>SNG= SNAP>or=NaNO(2). SNG ( approximately fourfold) and NaNO(2)( approximately 50-fold) were significantly more potent under low oxygen conditions. Cysteine, glutathione and SOD were without effect on GTN induced vasodilatation. However, all three agents significantly enhanced (six- to ninefold) the effects of NaNO(2)under similar conditions. When infused directly into the fetal-placental circulation during in vitro perfusion experiments the order of potency was GTN>SNP>or=SNG>or=SNAP>or=NaNO(2). When the nitrovasodilators were infused indirectly via the maternal intervillous space the order of potency was GTN>or=SNP>or=NaNO(2)>or=SNAP=SNG. Our observations suggest that there are important differences in the action of different classes of nitrovasodilator compounds on the fetal-placental circulation. The changes observed with SNG and NaNO(2)may be influenced by levels of tissue oxygenation.

Adolescent↗
PubMed2001

Overexpression of Na+/Ca2+ exchanger alters contractility and SR Ca2+ content in adult rat myocytes.

The functional consequences of overexpression of rat heart Na+/Ca2+ exchanger (NCX1) were investigated in adult rat myocytes in primary culture. When maintained under continued electrical field stimulation conditions, cultured adult rat myocytes retained normal contractile function compared with freshly isolated myocytes for at least 48 h. Infection of myocytes by adenovirus expressing green fluorescent protein (GFP) resulted in >95% infection as ascertained by GFP fluorescence, but contraction amplitude at 6-, 24-, and 48-h postinfection was not affected. When they were examined 48 h after infection, myocytes infected by adenovirus expressing both GFP and NCX1 had similar cell sizes but exhibited significantly altered contraction amplitudes and intracellular Ca2+ concentration ([Ca2+]i) transients, and lower resting and diastolic [Ca2+]i when compared with myocytes infected by the adenovirus expressing GFP alone. The effects of NCX1 overexpression on sarcoplasmic reticulum (SR) Ca2+ content depended on extracellular Ca2+ concentration ([Ca2+]o), with a decrease at low [Ca2+]o and an increase at high [Ca2+]o. The half-times for [Ca2+]i transient decline were similar, suggesting little to no changes in SR Ca2+-ATPase activity. Western blots demonstrated a significant (P < or = 0.02) threefold increase in NCX1 but no changes in SR Ca2+-ATPase and calsequestrin abundance in myocytes 48 h after infection by adenovirus expressing both GFP and NCX1 compared with those infected by adenovirus expressing GFP alone. We conclude that overexpression of NCX1 in adult rat myocytes incubated at high [Ca2+]o resulted in enhanced Ca2+ influx via reverse NCX1 function, as evidenced by greater SR Ca2+ content, larger twitch, and [Ca2+]i transient amplitudes. Forward NCX1 function was also increased, as indicated by lower resting and diastolic [Ca2+]i.

Adenoviridae↗
PubMed2001

Sprint training shortens prolonged action potential duration in postinfarction rat myocyte: mechanisms.

Two electrophysiological manifestations of myocardial infarction (MI)-induced myocyte hypertrophy are prolongation of action potential duration (APD) and reduction of transient outward current (I(to)) density. Because high-intensity sprint training (HIST) ameliorated myocyte hypertrophy and improved myocyte Ca(2+) homeostasis and contractility after MI, the present study evaluated whether 6-8 wk of HIST would shorten the prolonged APD and improve the depressed I(to) in post-MI myocytes. There were no differences in resting membrane potential and action potential amplitude (APA) measured in myocytes isolated from sham-sedentary (Sed), MI-Sed, and MI-HIST groups. Times required for repolarization to 50 and 90% APA were significantly (P < 0.001) prolonged in MI-Sed myocytes. HIST reduced times required for repolarization to 50 and 90% APA to values observed in Sham-Sed myocytes. The fast and slow components of I(to) were significantly (P < 0.0001) reduced in MI-Sed myocytes. HIST significantly (P < 0.001) enhanced the fast and slow components of I(to) in MI myocytes, although not to levels observed in Sham-Sed myocytes. There were no significant differences in steady-state I(to) inactivation and activation parameters among Sham-Sed, MI-Sed, and MI-HIST myocytes. Likewise, recovery from time-dependent inactivation was also similar among the three groups. We suggest that normalization of APD after MI by HIST may be mediated by restoration of I(to) toward normal levels.

Action Potentials↗
PubMed2001

[Analysis of association between gene polymorphisms of microsomal epoxide hydrolase (EPHX1) and infant birthweight].

We investigated association between genetic polymorphisms of EPHX1 in mother and infant birthweight. Data of 342 female workers were collected in textile mill. A total of 342 mothers were genotyped for the His139Arg polymorphism of EPHX1 by a polymerase chain reaction-restriction fragment length polymorphism assay. Using multiple linear regression models, we estimated the adjusted association between polymorphisms of EPHX1 and birthweight, with adjusted for potential confounders. We found that polymorphisms of EPHX1 were closely associated with reduced birthweight (beta +/- SE = -149 g +/- 56, P = 0.0083) after adjustment for major cofounders. In subgroup of passive smoking analysis, the polymorphisms of EPHX1 were highly associted with birthweight for those with passive smoking (beta +/- SE = -234 g +/- 88, P = 0.0088); The significant association of EPHX1 polymorphisms with reduced birthweight were showed for those with working stress (beta +/- SE = -157 g +/- 59, P = 0.0079). Our data provide polymorphisms of EPHX1 in mothers were significant association with birthweight of their infant, and showed gene-environmental interaction in relation to birthweight.

Birth Weight↗
PubMed2001

[Cloning and sequencing of prolactin gene cDNA in three chicken breeds].

The total RNA was extracted from the pituitary of two Chinese native chicken breeds, Yuehuang and Taihe Silkies, and one layer Isa, using RNeasy Kit (QIAGEN, Germany). The total RNA was used to synthesize a specific fragment with RT-PCR, in which the primers were designed based on the sequence of broiler prolactin gene cDNA. The specific fragment was ligated to a linear plasmid pBSSK and cloned with XL1-Blue. The sequencing of prolactin cDNA was carried out with ABI PRISH 377XL DNA Sequencer after cloning. The cDNA sequences and deduced amino acid sequences of prolactin gene of two Chinese native chicken breeds and one layer were compared with that of broiler, dwarf chicken and turkey. There was 93.97%-99.89% cDNA sequence homology among Chinese native, layer, broiler and dwarf chickens, in which there was the highest (99.87%) between those of Taihe and dwarf chickens. There was 98.25%-100% deduced amino acid sequence homology among Chinese native, layer, broiler and dwarf chickens, in which there was the highest (100%) between those of Taihe Silkies and dwarf chickens. It was found that Yuehuang and Taihe Silkies had the same signal peptide cleavage site Leu-Pro-Ile-Cys among amino acids sequence deduced from pre-prolactin cDNA as broiler, dwarf and turkey, while layer Isa had a different cleavage site Pro-Pro-Ile-Cys. Such difference might cause a different translation processing of pre-prolactin, which could make layer Isa non-broody. There were different amino acids in the positions 71, 141, 150 and 175 of deduced prolactin amino acid sequences among Yuehuang, Taihe Silkies, layer, broiler and dwarf chickens. There was a heparin-binding site in positions 175-181 (L-R-R-D-S-H-K) among prolactin amino acid sequences of broiler and Taihe Silkies.

Amino Acid Sequence↗
PubMed2001

[Chromosomal location and molecular marker of resistance gene to Puccinia striiformis west. in Leymus mollis Trin. Hara].

The hybrid wheat line, 93784 is a stable line selected from progenies of Leymus molli Trin. Hara x common wheat, which shows a very high level of resistance to yellow rust. The results of GISH using genomic DNA of Leymus mollis as probe indicated that the 93784 was a wheat-Leymus mollis small segment translocation line, and the translocated alien chromosome fragment were located on a pair of short arm terminals of what chromosomes. Using this translocation line, we established F2 segregation population and identified its yellow rust resistance in adult stage. Genetic analysis suggested that the yellow rust resistance of 93784 was controlled by a single gene. The gene was located on the translocated chromosome segments of Leymus mollis. We called it YrLm. By AFLP analysis with Taq I (T1-T4)/Pst I (P1-P6) primes in individuals of F2 segregation population and their susceptive and resistant parents, we screened a molecular marker that linked to yellow rust resistance gene YrLm. We also cloned and sequenced the molecular marker. The length of the marker is 205 bp, named P1T(3)205.

Chromosome Mapping↗
PubMed2001

[Determination of 1,1'-peroxydicyclohexylamine by gas chromatography].

A method for the determination of 1,1'-peroxydicyclohexylamine and cyclohexanone by gas chromatography was investigated. The conditions were optimized by changing the stationary liquid, internal standard and injector temperature. The gas chromatographic conditions were as follows: flame ionization detector; 10% OV-101 column; the injector temperature, 140 degrees C; temperature programming; internal standard, dodecane. All components and internal standard were separated in 11 min. The method is simple, rapid, sensitive and reproducible.

English Abstract↗
PubMed2001

[On cleanliness of hands in diminution of Ascaris lumbricoides infection in children].

OBJECTIVE: To study the relationship between cleanliness of children's hands and diminution of Ascaris lumbricoides infection. METHODS: Before the study all persons positive for ascaris eggs in the preliminary survey were treated with albendazole. Hand-washing habit before meal and after defecation was kept in children of experimental group, but not in the control group. Kato thick smear stool examination was done once every two months for one year to compare the new infection rates in children without ascaris infection in the two groups, and the reinfection rates in the cured negative cases were also compared between them in half a month after chemotherapy. RESULTS: All the new infection rates as well as reinfection rates of each reexamination in the experimental group were significantly lower than that of the control group (P < 0.001). Reexamination one year later showed that the ascaris infection rate of the experimental group was 35.2%, reducing by 48.5% as compared with 68.3% before the operation of the project; while ascaris infection rate of the control group was 73.7%, increasing by 78.0% as compared with 41.4% before the operation of the project. CONCLUSION: Washing hands with toilet soap to keep hands clean can significantly reduce ascaris infection rate.

Ascariasis↗