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Biomedical subjects

Q Xu

Publications and source records attributed to Q Xu.

At least 181 records · Page 10Linked to original sources
PubMed2000

[An observation of the immuno-persistence after inoculating with the domestic BRD II strain rubella vaccine among infants and young children].

OBJECTIVE: To study the immuno-persistence after inoculating with the domestic BRD II strain rubella vaccine among infants and young children. METHODS: Hemagglutination inhibition (HI) antibody detection method was used to test on children at age 6 to 18 months without rubella infection or rubella vaccine immunization in Yantai city of Shandong province and were selected for the observation of the immuno-persistence against the domestic BRD II strain rubella vaccine from 1995 to 1998. RESULTS: Positive rates of HI antibody among children of 6, 7, 8, 9, 12 and 18 month-old of inoculation were 94.44%, 97.22%, 96.67%, 100.00%, 100.00%, 100.00% and 93.10%, 93.55%, 96.77%, 96.97%, 100.00%, 100.00% (P > 0.05), in one or two years respectively. The geometric mean reverse titers (GMRTs) were about 50% lower than that after 1 month after 1 year. Similar results were found that after 2 years GMRTs was about 50% lower than that after 1 year of inoculation. There was highly significant difference on GMRTs of HI antibody between infants with 6 to 7 month-olds (29.89) and young children with 8 to 18 month-olds (53.00) after 2 years of inoculation (t = 3.58, P < 0.001). CONCLUSION: The immunization schedule at the first dose for BRD II strain rubella vaccine should be started when the child is 8 month old. For the second dose, the immunization schedule used in other developed countries should be referred adopted in China.

Antibodies, Viral↗
PubMed2000

[Effect of green and yellow vegetables on serum carotenoid in children].

OBJECTIVE: To assay the effect of green and yellow vegetables on serum carotenoid concentration and its relation to serum retinol level in children. METHODS: A ten-week green and yellow vegetable intervention study was conducted in children aged 5.3 to 6.4 years of two classes in a kindergarten in Tai'an City of Shandong Province in early September 1996, one class of light-colored vegetable supplemented with daily 193 grams of light colored vegetables, such as cabbage, Chinese cabbage, potato, cucumber, cauliflower and turnip, and 56 grams of yellow-green vegetables, such as spinach, Chinese chive, carrots and red yams; and the other one of yellow-green vegetables with daily 238 grams of yellow-green vegetables and 34 grams of light colored vegetables, both without change in regular diet. Venous blood specimens were collected before and after the experiment from each of the subjects. Serum retinol and carotenoid were determined with high performance liquid chromatography. RESULTS: Serum level of carotenoid, including all-trans-beta-carotene, cis-beta-carotene, cryptoxanthin and lutein were significantly higher after intervention in yellow-green vegetable group, as compared to their baseline levels. However, in the light-colored vegetable group, all those components, including all-trans-beta-carotene, 13-cis-beta-carotene and lutein, decreased significantly after intervention, as compared with those at their baseline levels. Serum carotene level correlated significantly with that of retinol, and their coefficient of correlation was greater in the winter than in the autumn. CONCLUSION: Carotenoid nutrition status can be improved by supplementation of green and yellow vegetables.

Carotenoids↗
PubMed2000

[Mechanism of anti-inflammatory action of Huanglian Jiedu decoction a traditional Chinese prescription].

OBJECTIVE: To elucidate the mechanism of anti-inflammatory action of Huanglian Jiedu Decoction (HJD). METHODS: An acute inflammatory air-pouch was established in mice by s.c. injecting air and 1% carrageenan. A mouse endotoxeamia induced by lipopolysaccharide was also used. Splenocyte proliferation was quantified with 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetery. NO2- concentration was examined by a Griess reagent and interleukin-1 activity was evaluated in thymocyte proliferation. RESULTS: HJD significantly inhibited the leukocyte infiltration and PGE2 production in the mouse air-pouch model. In the in vitro assay, HJD significantly inhibited concanavalin A(Con A)-induced transformation of spleen cells isolated from the endotoxeamia mice, but did not influence that from the normal mice. HJD did not affact Con A-induced interleukin-2 production in splenocytes in either normal or endotoxeamia mice. HJD remarkably reduced interleukin-1 and NO production in peritoneal macrophages elicited by lipopol ysaccharide. CONCLUSION: HJD displays an anti-inflammatory effect mainly through inhibiting the production of inflammatory cytokines including IL-1, NO and PGE2.

Animals↗
PubMed2000

[Determination of nodakenin in Peucedanum].

OBJECTIVE: To establish a HPLC method to determine the contents of nodakenin in Peucedanum. METHOD: The determination method was achieved by RP-HPLC on an ODS column by UV detection at 334 nm; with nodakenin as external standard and H2O-CH3OH-CH3CN(75:5:20) as mobile phase. RESULT: Several samples of 6 species of Peucedanum were analyzed by this method. The contents of nodakenin ranged from 0.005%-3.090%. CONCLUSION: Nodakenin cannot be used to control the quality of Peucedanum for pharmaceutical use, but this method is a simple and feasible way to control the quality of P. decursivum.

Apiaceae↗
PubMed2000

[Determination of blood glucose by chemiluminescent flow-injection analysis with immobilized glucoxidase column].

Luminol-hemin system was used for chemiluminescent flow-injection analysis with immobilized glucoxidase(GOD) column to determine blood glucose. The method is fast, simple and sensitive. Blood samples were diluted to 1:1000 and pumped into the flow-injection analyzer for direct detection. The sampling frequency was 30 samples/h, with a detection limit of 7.2 x 10(-9) mol/L(1.30 micrograms/L). A column packed with 36 milligrams of CPG could be used nearly 200 times. The determination results of glucose in serum by this method were in good agreement with those obtained by the routine GOD spectrophotometric method (correlation coefficient r = 0.90, P > 0.05). Recoveries of this method were 94.0%-107.2%.

Blood Glucose↗
PubMed2000

[Study of chromosome pellicle by indirect immunoflourescence method and antigen analysis in Vicia faba].

The autoimmune antiserum specific to pellicle of human metaphasic chromosomes from a lupus patient was used to stain metaphasic chromosome Vicia faba by means of indirect immunoflourescence method. It was found that the pellicles of vicia metaphasic chromosomes was positively stained. The antigen of Vicia faba recognized by the antiserum was also examined by PAGE of total cell lysate and western blotting.

Antigens↗
PubMed2000

[A study on the determination method of biological function of BRF].

This study was aimed to establish a method for determining the biological function of biological wave regulating factor (BRF). Proteus mirabilis was used to set up the experimental model. The biological function of the component obtained from wave growth media beneath the bacterial colony rings resulting from bacterial proliferation was determined in biological wave test by analytically microbiological method. The results indicated that BRF could enhance biological wave and shorten its period. The method is of some value in studying the regulative mechanism of biological wave.

Bacterial Proteins↗
PubMed2000

[Prevention and release of epidural-morphine-induced urinary retention with phenoxybenzamine and neostigmine].

OBJECTIVE: To study the effects of preoperative phenoxybenzamine (o.p) on preventing epidural-morphine-induced urinary retention and effects of neostigmine on releasing it. METHODS: 80 patients who received epidural morphine to release postoperative pain were divided into 4 groups randomly and received preoperative phenoxybenzamine (group P, n = 20), neostigmine (i. m) when urinary retention happened (group N, n = 20), both drugs (group U, n = 20), and without drugs (Control, n = 20), respectively. The incidences of urinary retention and release were observed. RESULTS: No significant decrease (P > 0.05) happened after operation in the incidence of epidural-morphine-induced urinary retention both in the group P and in the group N. Neostigmine(i. m) could significantly release (P < 0.001) the epidural-morphine-induced urinary retention when phenoxybenzamine was administrated preoperatively. CONCLUSION: Preoperative phenoxybenzamine can not prevent epidural-morphine-induced urinary retention. Neostigmine can release the urinary retention only when preoperative phenoxybenzamine is used.

Adolescent↗
PubMed2000

[Alternative splicing of de novo methyltransferase gene 3b in adult and newborn mice].

OBJECTIVE: To unravel the biological significance of the alternative splicing of de novo methyltransferase 3b, expression of the Dnmt3b gene in various tissues and developmental stages was investigated in postnatal mice. METHODS: RT-PCR and capillary electrophoresis were employed to analyze the alternative splicing pattern of Dnmt3b in tissues of newborn and adult mice. The results had been further reaffirmed by repeating and statistics analysis. Bioinformatics tools were used to predict the structure and hydrophobicity of the Dnmt3b exon10 coding sequence. RESULTS: Isoform with Dnmt3b exon10 was the abundant form in lung of newborn mice and in liver of both newborn and adult mice, while in other tissues of newborn and adult mice, the spliced isoform was presented as the predominant one. Peptide encoded by Dnmt3b exon10 was mainly random coil on the surface of Dnmt3b protein. CONCLUSIONS: The data demonstrate that the specific expression of Dnmt3b exists in tissues and developmental stages of postnatal mice. The alternative splicing of the exon 10 of Dnmt3b is possibly involved in the regulation of Dnmt3b's catalytic function. These results provide an insight into the developmental regulation and physiological function of the alternative splicing of the Dnmt3b gene.

Alternative Splicing↗
PubMed1999

Conservation of structure and function among histidine-containing phosphotransfer (HPt) domains as revealed by the crystal structure of YPD1.

In Saccharomyces cerevisiae, the SLN1-YPD1-SSK1 phosphorelay system controls a downstream mitogen-activated protein (MAP) kinase in response to hyperosmotic stress. YPD1 functions as a phospho-histidine protein intermediate which is required for phosphoryl group transfer from the sensor kinase SLN1 to the response regulator SSK1. In addition, YPD1 mediates phosphoryl transfer from SLN1 to SKN7, the only other response regulator protein in yeast which plays a role in response to oxidative stress and cell wall biosynthesis. The X-ray structure of YPD1 was solved at a resolution of 2.7 A by conventional multiple isomorphous replacement with anomalous scattering. The tertiary structure of YPD1 consists of six alpha-helices and a short 310-helix. A four-helix bundle comprises the central core of the molecule and contains the histidine residue that is phosphorylated. Structure-based comparisons of YPD1 to other proteins having a similar function, such as the Escherichia coli ArcB histidine-containing phosphotransfer (HPt) domain and the P1 domain of the CheA kinase, revealed that the helical bundle and several structural features around the active-site histidine residue are conserved between the prokaryotic and eukaryotic kingdoms. Despite limited amino acid sequence homology among HPt domains, our analysis of YPD1 as a prototypical family member, indicates that these phosphotransfer domains are likely to share a similar fold and common features with regard to response regulator binding and mechanism for histidine-aspartate phosphoryl transfer.

Amino Acid Motifs↗
PubMed1999

Association of serum antibodies to heat-shock protein 65 with carotid atherosclerosis : clinical significance determined in a follow-up study.

BACKGROUND: Previous work has proved that increased titers of antibodies against heat-shock protein (hsp) 65 are associated with atherosclerotic lesions independently of other established risk factors. The present follow-up study was designed to further scrutinize the association of hsp antibodies and atherosclerosis and evaluate the possible predictive value of these antibodies for the development and/or progression of lesions in the same population. METHODS AND RESULTS: A total of 750 subjects 45 to 74 years old were recruited, and the rate of participation was 93.6%; 58 subjects died between 1990 and 1995. All participants were subjected to determination of serum antibodies against hsp65 and sonography to assess carotid atherosclerotic lesions and evaluate other risk factors, ie, age, sex, body mass index, blood cholesterol, apolipoprotein B, apolipoprotein A, triglycerides, lipoprotein(a), fibrinogen, leukocyte number, antithrombin III, ESR, ferritin, hypertension, smoking, and diabetes mellitus. Our data show that hsp65 antibody titers in the population emerged as highly consistent over a 5-year observation period (r=0.78, P<0.0001). Titers were significantly elevated in subjects with progressive carotid atherosclerosis and correlated with intima/media thickness. Multiple linear regression analysis documented these associations to be independent of age, sex, and other risk factors. Subanalyses revealed a preferential association of hsp65 antibody titers with advanced lesions (odds ratio, 1.42; 95% CI, 1.02 to 1.98; P=0.039). Other risk factors neither confounded nor modified this association. Finally, hsp65 antibody titers significantly predicted the 5-year mortality (hazard ratio, 1.52; 95% CI, 1.14 to 2.03; P<0.001). CONCLUSIONS: These findings indicate a sustained existence of anti-hsp65 antibodies in subjects with severe atherosclerosis, which is predictive for mortality.

Antibodies↗
PubMed1999

Structural insights into the mechanism of intramolecular proteolysis.

A variety of proteins, including glycosylasparaginase, have recently been found to activate functions by self-catalyzed peptide bond rearrangements from single-chain precursors. Here we present the 1.9 A crystal structures of glycosylasparaginase precursors that are able to autoproteolyze via an N --> O acyl shift. Several conserved residues are aligned around the scissile peptide bond that is in a highly strained trans peptide bond configuration. The structure illustrates how a nucleophilic side chain may attack the scissile peptide bond at the immediate upstream backbone carbonyl and provides an understanding of the structural basis for peptide bond cleavage via an N --> O or N --> S acyl shift that is used by various groups of intramolecular autoprocessing proteins.

Aspartylglucosylaminase↗
PubMed1999

Cyclic strain stress-induced mitogen-activated protein kinase (MAPK) phosphatase 1 expression in vascular smooth muscle cells is regulated by Ras/Rac-MAPK pathways.

Recently, we demonstrated that mechanical stress results in rapid phosphorylation or activation of platelet-derived growth factor receptors in vascular smooth muscle cells (VSMCs) followed by activation of mitogen-activated protein kinases (MAPKs) and AP-1 transcription factors (Hu, Y., Bock, G., Wick, G., and Xu, Q. (1998) FASEB J. 12, 1135-1142). Herein, we provide evidence that VSMC responses to mechanical stress also include induction of MAPK phosphatase-1 (MKP-1), which may serve as a negative regulator of MAPK signaling pathways. When rat VSMCs cultivated on a flexible membrane were subjected to cyclic strain stress (60 cycles/min, 5-30% elongation), induction of MKP-1 proteins and mRNA was observed in time- and strength-dependent manners. Concomitantly, mechanical forces evoked rapid and transient activation of all three members of MAPKs, i.e. extracellular signal-regulated kinases (ERKs), c-Jun NH(2)-terminal protein kinases (JNKs), or stress-activated protein kinases (SAPKs), and p38 MAPKs. Suramin, a growth factor receptor antagonist, completely abolished ERK activation, significantly blocked MKP-1 expression, but not JNK/SAPK and p38 MAPK activation, in response to mechanical stress. Interestingly, VSMC lines stably expressing dominant negative Ras (Ras N17) or Rac (Rac N17) exhibited a marked decrease in MKP-1 expression; the inhibition of ERK kinases (MEK1/2) by PD 98059 or of p38 MAPKs by SB 202190 resulted in a down-regulation of MKP-1 induction. Furthermore, overexpressing MKP-1 in VSMCs led to the dephosphorylation and inactivation of ERKs, JNKs/SAPKs, and p38 MAPKs and inhibition of DNA synthesis. Taken together, our findings demonstrate that mechanical stress induces MKP-1 expression regulated by two signal pathways, including growth factor receptor-Ras-ERK and Rac-JNK/SAPK or p38 MAPK, and that MKP-1 inhibits VSMC proliferation via MAPK inactivation. These results suggest that MKP-1 plays a crucial role in mechanical stress-stimulated signaling leading to VSMC growth and differentiation.

Animals↗
PubMed1999

Inhibition of neointima hyperplasia of mouse vein grafts by locally applied suramin.

BACKGROUND: Saphenous vein grafts are widely used for aortocoronary bypass surgery as treatment for severe atherosclerosis and often are complicated by subsequent occlusion of the graft vessel. METHODS AND RESULTS: We described a mouse model of venous bypass graft arteriosclerosis that can be effectively retarded by locally applied suramin, a growth factor receptor antagonist. Mouse isogeneic vessels of the vena cava veins pretreated with suramin were grafted end to end into the carotid arteries and enveloped with a mixture of suramin (1 mmol/L) and pluronic-127 gel. In the untreated group, vessel wall thickening was observed as early as 1 week after surgery and progressed to 4-fold and 10-fold the original thickness in grafted veins at 4 and 8 weeks, respectively. Pluronic-127 gel alone did not influence neointima formation. Suramin treatment reduced the neointima hyperplasia 50% to 70% compared with untreated controls. Immunohistochemical studies demonstrated that a significant proliferation of vascular smooth muscle cells (SMCs) constituted neointimal lesions between 4 and 8 weeks. The majority of SMCs expressed platelet-derived growth factor (PDGF) receptors-alpha and -beta, which were significantly reduced by suramin treatment. In vitro studies indicated that suramin completely blocked PDGF receptor activation or phosphorylation stimulated by PDGF-AB, inhibited activation of mitogen-activated protein kinase (ERK) kinases (MEK1/2) and ERK1/2, and abrogated transcription factor AP-1 DNA-binding activity. CONCLUSIONS: Suramin inhibited SMC migration and proliferation in vivo and in vitro by blocking PDGF-initiated PDGF receptor and MAPK-AP-1 signaling. These findings indicate that locally applied suramin is effective in a mouse model of venous bypass graft arteriosclerosis.

Animals↗
PubMed1999

Cloning of a galactose-binding lectin from the venom of Trimeresurus stejnegeri.

A galactose-binding lectin isolated from the venom of Trimeresurus stejnegeri is a homodimer C-type lectin. The cloned cDNA encoding the monomer of Trimeresurus stejnegeri lectin (TSL) was sequenced and found to contain a 5'-end non-coding region, a sequence which encodes 135 amino acids, including a typical 23 amino acid signal peptide followed by the mature protein sequence, a 3'-end non-coding region, a polyadenylation signal, and a poly(A) region. To completely characterize the deduced amino acid sequence, on-line HPLC-MS and tandem MS were used to analyse the intact monomer and its proteolytic peptides. A modified peptide fragment was also putatively identified by HPLC-MS analysis. The deduced amino acid sequence was found to contain a carbohydrate-recognition domain homologous with those of some known C-type animal lectins. Thus TSL belongs to group VII of the C-type animal lectins as classified by Drickamer [(1993) Prog. Nucleic Acid Res. Mol. Biol. 45, 207-232]. At present, a number of C-type lectins have been purified from snake venom, but most of them have been characterized only at the protein level. To our knowledge, this is the first known cDNA sequence of a true C-type lectin from snake venom.

Amino Acid Sequence↗
PubMed1999

Astilbin selectively induces dysfunction of liver-infiltrating cells--novel protection from liver damage.

The present study aimed to examine the effect of astilbin, a flavanoid, on liver injury. When administered during the effector but not induction phase, astilbin significantly decreased the liver injury induced by delayed-type hypersensitivity to picryl chloride in mice. The pretreatment of nonparenchymal cells but not hepatocytes with astilbin in vitro caused a concentration- and time-dependent inhibition against the damage. Nonparenchymal cells isolated from astilbin-administered mice also showed a significant incompetence of hepatotoxicity, correlated with the inhibition of serum transaminase elevation. However, astilbin did not protect from CCl4-induced liver damage. Furthermore, the flavanoid markedly promoted the apoptosis of nonparenchymal cells from liver-injured mice, whereas did not influence those from naive mice. These results suggest that astilbin provides improvement against liver injury through a selective dysfunction of liver-infiltrating cells rather than by protecting the hepatocyte membrane. Such characteristics will be of significance to pave a new way for treating immunologically related liver diseases and for developing new drugs.

Animals↗