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Biomedical subjects

J Xu

Publications and source records attributed to J Xu.

At least 595 records · Page 33Linked to original sources
PubMed1999

Apoptotic cell death of human gastric tumor induced by nucleosides from CD57+HLA-DRbright natural suppressor cell line.

CD57+HLA-DRbright natural suppressor (57.DR-NS) cell line derived from human decidual tissue generated apoptosis in a human gastric carcinoma cell line (GCIY) but not in a human diploid normal cell line (WI-38). The factors released from 57.DR-NS cells were purified by thin-layer-chromatography (TLC) and separated by high performance liquid chromatography (HPLC) into six components. The physicochemical structures of the six components were determined as a series of nucleosides and their modified forms collectively termed in a previous study. They could generate apoptotic cell death of GCIY malignant target cells, but not disturb the viability of WI-38 normal target cells. The administration of AINs into GCIY tumor bearing SCID mice resulted in drastic suppression of tumor growth followed by the decrease in tumor size due to the occurrence of apoptosis in tumor tissues.

Animals↗
PubMed1999

Regulation and functions of the protein C anticoagulant pathway.

The protein C pathway plays a critical role in the negative regulation of the blood clotting process. We recently identified an endothelial cell receptor for protein C/activated protein C (APC). The receptor is localized almost exclusively on endothelial cells of large vessels and is present at only trace levels or indeed absent from capillaries in most tissues. Patients with sepsis or lupus erythematosus exhibit elevated levels of plasma EPCR which migrates on gels as a single band and is fully capable of binding protein C/APC. There is no correlation with thrombomodulin levels, probably due to different vascular localizations and/or cellular release mechanisms. To understand the mechanisms by which EPCR plasma levels are elevated, we examined EPCR mRNA expression in a rat endotoxin shock model. The EPCR mRNA gene exhibited an early immediate gene response to endotoxin with the mRNA levels increasing nearly 4 fold in the first 3-6 hrs, before returning toward baseline. Plasma levels of EPCR also rose about 4 fold with little change in tissue EPCR levels. Both processes were markedly attenuated by hirudin suggesting that thrombin was responsible for increases in mRNA and plasma EPCR levels. At the level of mRNA, the induction is mediated by a thrombin response element in the 5' flanking region of the gene. Direct thrombin infusion and cell culture experiments support this contention. On endothelium, thrombin is capable of releasing cell surface EPCR and this process is blocked by the metalloproteinase inhibitor orthophenanthroline. Taken together these studies indicate that elevation in soluble plasma EPCR reflects endothelial cell activation in the larger vessels and is likely to be an indication of local thrombin generation near these vessel surfaces.

Animals↗
PubMed1999

[Genetic polymorphisms of serum orosomucoid in Han population in Nanjing of China].

OBJECTIVE: To determine the genetic polymorphisms of serum orosomucoid (ORM) in Han population in Nanjing of China and provide genetic data for studying the individual variance in the plasma protein binding of weak alkaline drugs. METHODS: The desialylated sera from 220 unrelated subjects were analyzed by isoelectric focusing on polyacrylamide gels followed by immunoblotting. RESULTS: The band patterns of ORM showed that the polymorphism of the structural locus ORM1 was controlled by three codominant autosomal alleles, ORM1*F1, ORM1*F2 and ORM1*S, which presented five phenotypes, ORM1 F1(47.27%), ORM1 S(5.46%), ORM1 F1F2 (3.18%), ORM1 F1S(43.64%), and ORM1 F2S(0.45%). The allele frequencies were: ORM1*F1=0.7068, ORM1*F2=0.0182, ORM1*S=0.2750. CONCLUSION: The ORM1 locus is polymorphic and the ORM2 locus is monomorphic in sera from the Han people in Nanjing of China.

Alleles↗
PubMed1999

Priming of the neutrophil respiratory burst is species-dependent and involves MAP kinase activation.

BACKGROUND: Priming of the neutrophil respiratory burst has been implicated in the pathogenesis of multi-system organ failure (MSOF) after sepsis and trauma. The intracellular signal transduction pathways that mediate priming are unclear. METHODS: Human, porcine, rabbit, rat, and mouse neutrophils were assayed by luminol-dependent chemiluminescence in whole blood and purified neutrophil preparations. Multiple priming agents and agonists were studied, as was inhibition of priming by the p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 and the Mek 1/2 inhibitor PD98059. RESULTS: Priming by tumor necrosis factor alpha (TNF-alpha), interleukin-8 (IL-8), and granulocyte-macrophage colony-stimulating factor (GM-CSF) was significantly inhibited by SB203580, whereas platelet-activating factor (PAF) priming was unaffected. Neither TNF-alpha nor PAF primed polymorphonuclear neutrophils (PMNs) within whole blood for N-formyl-methionyl-leucyl-phenylalanine (f-MLP) activation, in contrast to activation by complement-opsonized zymosan (OPZ) or low-dose phorbolmyristate acetate (PMA). Both TNF-alpha and PAF, however, primed purified neutrophils for f-MLP activation. In contrast to human and porcine PMNs, rabbit, rat, and mouse PMNs could not be primed by TNF-alpha or PAF, regardless of the final agonist. CONCLUSIONS: Priming of the PMN respiratory burst proceeds through multiple signaling pathways, depending on the particular priming agent and agonist pair. Differences in priming between PMNs in whole blood and purified preparations may be physiologically significant. There is a pronounced species dependency in the ability to prime the neutrophil respiratory burst.

Animals↗
PubMed1999

Total Synthesis of Sanglifehrin A.

The immunosuppressive agent sanglifehrin A has been prepared for the first time by total synthesis. The construction of the macrocyclic unit of the target molecule was achieved through a selective intramolecular Stille coupling, and the spirolactam unit by Paterson-aldol reactions. The final steps involve an intermolecular Stille coupling and the opening of the internal acetal unit. This convergent synthesis opens the way for the synthesis of libraries of novel sanglifehrin analogues for biological screening.

Journal Article↗
PubMed1999

Hirudin display on the surface of bacteriophage M13.

Hirudin was fused to the N terminus of M13 minor protein gp3 (197-406) through a linker GGGS by inserting both the hirudin gene and the gp8 signal sequence into the modified phagemid vector pCANTAB 5V to construct pCANTAB 5G8-Hir. The expressed fusion protein was directed by gp8 signal peptide into the periplasm and assembled to the phage particle to form the hirudin-phage. The fusion protein and fusion phage were detected with biotin-thrombin by Western blotting analysis. Antithrombin activity analysis confirmed that the hirudin portion in the fusion protein and fusion phage bear similar native conformation. The successful display of hirudin on the surface of M13 phage laid a sound foundation for the further study on directed evolution of antithrombotic proteins with altered properties.

Antithrombins↗
PubMed1999

Attenuation of the induced differentiation of HL-60 leukemia cells by mitochondrial chaperone HSP70.

The HSP70 family of heat shock proteins, which are involved in development and cellular differentiation, is elevated in various tumor cell lines. To examine the role of these proteins in neoplastic cell differentiation, four members of the HSP70 multiple gene family (i.e., HSP70, HSC70, GRP78, and mtHSP70) were examined during the induced differentiation of HL-60 promyelocytic leukemia cells. Western analyses showed that continuous exposure for 48 h of HL-60 cells to the differentiation-inducing agents, all-trans retinoic acid, 1,25-dihydroxyvitamin D3, or N-methylformamide, resulted in decreases in mitochondrial HSP70 (mtHSP70), with little change in the levels of HSP70, HSC70, and GRP78. To gain information on the role of mtHSP70 in the differentiation process, HL-60 cells were transfected with either murine mthsp70 cDNA or vector alone. Slightly greater than twofold increases in mtHSP70 protein levels occurred in cells transfected with the mthsp70 cDNA. In vector-transfected HL-60 cells, myeloid differentiation, measured as an increase in CD31 expression and nitroblue tetrazolium positivity, was observed following 3-6 days of treatment with each of the three inducing agents. In contrast, cell differentiation induced by each agent was markedly attenuated in mthsp70-transfected HL-60 cells. These findings suggest that a decrease in mtHSP70 is important for the induced differentiation of HL-60 cells.

Antineoplastic Agents↗
PubMed1999

Factors influencing the synthesis of monoester and diester from polyethylene glycol400 and oleic acid by lipase.

Factors influencing the synthesis of mono- and diester of polyethylene glycol400 (PEG400) oleate with immobilized lipase from Candida sp.1619 as biocatalyst were investigated. Mono- and diester were formed with different molar ratios of the substrates after reacting for 6 hours. The amount of monoester to diester formed was in the range of 3.5:1 to 4.1:1 when the molar ratio of acid to PEG400 was 0.25:1 to 2:1. Almost equal amounts of mono- and diesters were produced when the molar ratio of acid to PEG400 was 3:1 to 8:1. When the equilibrium of reaction was reached (22 hours), only diester was found in the reaction mixture with different molar ratio of substrates. The amount of monoester to diester was 1:3.2 in the reaction system containing hexane, even the molar ratio of acid to PEG400 was 2:1.

Candida↗
PubMed1999

[Contraceptive efficacy of Sino-female condom: comparison with condom].

OBJECTIVE: To compare the contraceptive efficacy of Sino-female condom with condom. METHODS: 603 volunteer couples were randomly divided into two groups: 304 couples using female condom for contraception, and 299 using condom. Using lifetable method and log rank test, we compared the pregnancy rates and other discontinuation rates after follow-up for 6 months in two groups. RESULTS: No abnormal findings of cervical and vaginal smears were detected before and after this clinical trial in all 603 women. The follow-up rates at 6 months were 99.01% and 99.67% in the female condom group and condom group, respectively. The 6-month gross cumulative pregnancy rates were 1.06 and 1.69 per 100 women and the discontinuation rates due to allergy were 1.39 and 0.34, respectively. No difference was statistically significant (P > 0.05). However, the discontinuation rate for other causes in the female condom group was significantly higher than that in the condom group (P < 0.01). The main cause was that more than half of subjects were used to applying condom before this study. CONCLUSION: The contraceptive efficacy of Sino-female condom is as same as that of condom, and its clinical use is quite safe.

Adult↗
PubMed1999

Factors involved in the neuronal death during postischemic reperfusion: experimental study in rabbits.

OBJECTIVE: To explore the main pathogenic factors in the development of neuronal death during normothermic reperfusion in rabbits. METHODS: Ninety-six New Zealand rabbits were randomly allocated into two groups: group I served as non-ischemic controls; group II served as postischemic normothermic reperfusion models. Complete cerebral ischemia was induced by the four-vessel model for 30 minutes. After ischemia, rabbits in group II were further divided into three subgroups according to the duration of reperfusion: subgroup A, 30 minutes; subgroup B, 180 minutes and subgroup C, 360 minutes. Twenty-eight biochemical parameters in the brain were measured, and neuronal changes were observed by histomorphological assessment. Neurons of 12 regions were differentiated into four types: type A (normal), type B (mildly damaged), type C (severely damaged) and type D (necrotic). Bivariate correlate analysis between the levels of biochemical parameters and the percentages of each type of neurons was carried out. RESULTS: The main parameters involved in the progressive decrement of type A neurons were VIP, beta-EP, PGI2, T3, T4 and Na+, K(+)-ATPase; in the increment of type B were beta-EP and TXB2; in the increment of type C were GLU and TXB2/PGI2 respectively; in the stepwise increment of percentages of type D neurons were T4, Na+, K(+)-ATPase, GLU, T3 and VIP (P < 0.05). CONCLUSION: The main factors involved in the development of neuronal death during postischemic normothermic reperfusion in rabbits include hypermetabolism, deactivation of Na+, K(+)-ATPase, release of excitatory amino acids and disorder of neuropeptides.

Animals↗
PubMed1999

[A molecular epidemiology study on risk factors and mechanism of HBV intrauterine transmission].

OBJECTIVE: To clarify the risk factors and mechanism of HBV intrauterine infection by molecular epidemiology method. METHODS: We performed a case-control study. 402 HBsAg-positive pregnant women and their infants were collected as subjects. 15 infants infected by HBV intrauterine transmission were selected as case group and others as controls. Besides, HBsAg titer in 182 maternal sera and HBV DNA concentration in 185 maternal sera were determined. To identify the HBV infection in the placentas, immunohistochemistry stain and HBV DNA hybridization in situ were conducted. The data from both laboratory and epidemiological fields were analysed. RESULTS: The findings indicated that the positiveness of HBeAg in mother's sera (OR = 17.07) and the history of threatened premature labour (OR = 5.44) were the main risk factors. Intrauterine transmission was significantly related to HBsAg titers and HBV DNA concentration in mother's sera (P = 0.01). The results of immunochemistry stain and HBV DNA situ in hybridization in the placentas from 101 full-term pregnancy women showed that HBV infection rates had a decreasing trend (P = 0.0009) from mother's side to fetus's in placenta and there was a significant association between HBV intrauterine transmission and HBV infection in villous capillary endothelial cells in placenta (OR = 18.46, P = 0.0002). CONCLUSION: There might be a "cellular transfer" of HBV infection in the placenta. With regard to the mechanism of HBV intrauterine transmission; there are two transmission routes, namely, hemagenous route and cellular route.

Adult↗
PubMed1999

[Localization of a FLT3 ligand isoform in human tissues].

OBJECTIVE: To explore the localization of a human FLT3 ligand isoform deleted 139 bp of extracellular region. METHODS: Localization of the FLT3 ligand isoform in human tissues was studied by using PCR and RT-PCR. The PCR products were identified by DNA sequencing. RESULTS: FLT3 ligand was expressed in liver, fetal liver, bone marrow, muscle, kidney and peripheral blood cells and in four leukemia cell lines, but not in brain, while the FLT3 ligand isoform only in fetal liver and bone marrow. CONCLUSION: The FLT3 ligand isoform was expressed in hematopoietic cells and might be involved in hematopoiesis regulation.

Humans↗
PubMed1999

[Saikosaponin-d up-regulates GR mRNA expression and induces apoptosis in HL-60 cells].

OBJECTIVE: To research the effect of saikosaponin-d (SSd) on the expression of glucocorticoid receptor (GR) mRNA and induction of apoptosis in HL-60 cells. METHODS: Antiproliferation effects of SSd on HL-60 cells were determined by 3H-thymidine incorporation. Apoptosis of the SSd-treated cells was determined by DNA fragmentation analysis and flow cytometry. GR mRNA was analyzed by Northern blot analysis. RESULTS: After 48 h treatment with 10 micrograms/ml SSd, 3H-thymidine incorporation was decreased in HL-60 cells and the effects were time and dose dependent. DNA ladder appeared after 60 h treatment with SSd. The flow cytometry analysis showed HL-60 cells was arrested at G0/G1 phase and apoptotic peak appeared in sub-G1 phase. The expression of GR mRNA was increased. CONCLUSION: SSd up-regulates the expression of GR mRNA, inhibits the cell growth and induces apoptosis in HL-60 cells.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Clinical analysis of 1539 cases undergoing coronary artery bypass grafting.

OBJECTIVE: To analyze clinical factors affecting the outcome of coronary artery bypass grafting (CABG). METHODS: 1539 patients were divided into the following two groups based on admission sequence: group I (n = 570), 1974-1994; group II (n = 969), 1995-1998. Comparison of clinical data and procedure between the two groups was made. RESULTS: After CABG, 1482 patients were alleviated from angina, 57 patients died within 30 days of operation, with an overall mortality rate of 3.7%. The mortality rates in group I and group II were 7.9% and 1.2%, respectively. Since 1995, the mortality rate has significantly decreased. CONCLUSION: CABG is a safe and effective therapy for coronary heart disease. Surgical technique is a key factor affecting the outcome of CABG in selected patients.

Adult↗
PubMed1999

[Effect of antisense oligonucleotides on endothelin converting enzyme expression and endothlin-1 release from airway smooth muscle cells].

OBJECTIVE: To explore the mechanism of TNF-alpha induced ET-1 release and evaluate the effects of endothelin converting enzyme (ECE) antisense oligonucleotides (oDNS) on TNF-alpha induced ET-1 release from airway smooth muscle cells (ASMC). METHODS: ASMC transfected with the antisense oligonucleodides of ECE vectored with lipofectin were established. TNF-alpha induced ECE-mRNA expression and ET-1 release from above cultured cells were determined by RT-PCR and ELISA. RESULTS: ET-1 levels (10.1 +/- 0.3) ng/L and ECE expression (ECE/beta-actin: 0.228 +/- 0.015) in cultured ASMC incubated with 1,000 U/ml TNF-alpha were significantly higher than those in controls without TNF-alpha incubation (7.3 +/- 0.8) ng/L, (0.132 +/- 0.032, all P < 0.01). However, after transfecting antisence ECE-oDNS in those cells, ET-1 levels and ECE expressions were significantly lower than those in control cells without antisense transfection. The inhibition rates were (29 +/- 5)% and (35 +/- 12)% respectively. CONCLUSIONS: Abnormal expression of ECE mRNA may be a keypoint responsible for TNF-alpha induced ET-1 release in human ASMC; TNF-alpha induced ET-1 release and ECE mRNA expression from human ASMC are inhibited by antisense oligonucleotide of ECE.

Aspartic Acid Endopeptidases↗
PubMed1999

[Analysis of the oxide film of Ni-Cr porcelain alloy].

OBJECTIVE: In order to find out the causes of cervical gray line of PFM crown, the features of oxide film of Ni-Cr alloy were investigated. METHODS: 1. The phases were analyzed using x-ray radiation shield. 2. Compositions of oxide film and base metal were measured using electronic scanning microscope. 3. The thickness of oxide film and the variations of Ni, Cr, O in oxide film were evaluated using Auger electron spectroscope. RESULTS: 1. There were not only NiCr2O4 but also Cr2O3, SiO2, and gamma phase solid solution in the surface. 2. The weight contents of Cr and Si were higher while Ni was lower in oxide film than in the base. 3. Oxide film became much thicker(400 nm: 16 nm) after the temperature cycling. CONCLUSION: The medium-thicked oxide film was formed after baking, and it was not a complete film.

Chromium Alloys↗
PubMed1999

[Polylactic acid combined with recombinant human bone morphogenetic protein and basic fibroblast growth factor to repair the mandibular defects in rabbits].

OBJECTIVE: To study the effect of basic fibroblast growth factor(bFGF) on bone formation induced by recombinant human bone morphogenetic protein-2(rhBMP-2) in repair of mandibular defects in rabbits. METHODS: 56 adult domestic rabbits were classified into five groups. The mandiblar three-wall defects(1.5 cm x 0.5 cm, full thick) were created in right sides. The defects were implanted with various grafts: PLA/rhBMP-2/bFGF, PLA/rhBMP-2, PLA/bFGF, PLA and no implant as control group. At 2, 4 and 8 weeks after operation, the effectivenesses of defect repaire were observed by histological and roentgenographic analysis. RESULTS: The composite consisting of three materials stimulated more bone formation than of two materials, and the latter was more than single PLA(at 4 weeks postoperation, P < 0.05). All experimental groups, which had one or two growth factors, were significantly higher compared with control group in every stage of postimplantation. CONCLUSION: PLA has good biocompatibility, absorbability and osteoconductibility, rhBMP-2 and bFGF are cooperated in bone healing process, and PLA/rhBMP-2/bFGF is a promising bone substitute in clinical uses.

Animals↗