Biomedical subjects

Jun Zhang

Publications and source records attributed to Jun Zhang.

At least 343 records · Page 19Linked to original sources

PubMed2004

[Mammalian gene-transfer and expression efficiencies of baculovirus bacV-CMV-EGFPA].

It has been reported that baculoviruses could serve as a new gene-transfer vehicle for mammalian cells. We have previously constructed recombinant baculovirus BacV-CMV-EGFPA and have proven that mammalian cells could be effectively infected by the recombinant baculovirus. In this report, we studied the efficiency of baculovirus to deliver exogenous gene into twenty mammalian cells, including twelve human cell lines (WI-38, Hela, HepG2, 293, PLC/PRF/5, 143B, MCF-7, BGC-223, DMS 114, CNE, Raji, LCL-cm), seven murine cell lines (BNL 1ME A.7R.1, CHO-K1, L-929, JC, PT67, NIH3T3, P815) and one monkey cell line (CV1). Results showed that most mammalian cell lines could be transduced by the recombinant baculovirus, the transduction efficiencies of the human and monkey cell lines were markedly higher than that of murine cell lines, and the transduction efficiencies in adherent culture cell lines higher than that of suspend culture cell lines, implying that the infection efficiency of the baculovirus may be correlative with the organism used and the growth properties of the cell lines. The plasmid pcDNA3. 1-EGFP, which contains the CMV promoter and EGFP reporter gene, was next transfected by LipofectAMINE into a number of mammalian cells, especially those cells that were low in the baculovirus transfection. Results showed that the CMV promoter could effectively direct the expression of the reporter gene in these mammalian cells. Therefore the gene-expression efficiencies in different mammalian cell lines by the recombinant baculovirus which contains the same CMV promoter were dictated by the ability of the baculovirus to enter the cell lines. This study suggested that the recombinant baculovirus vector is more suitable for gene expression in primate adherent culture cells than in murine cells and suspend culture cells.

Animals↗

PubMed2004

[Interface domain of hepatitis E virus capsid protein homodimer].

Hepatitis E is a main cause of acute viral hepatitis in developing countries where it occurs as sporadic cases and in epidemics form. The causative agent, hepatitis E virus, is transmitted primarily by the fecal-oral route. The approximately 7.5 kb positive-sense single-strand RNA genome includes three open reading frames (ORFs), one of which (ORF2) is postulated to encode the major viral capsid protein (pORF2) of 660 amino acid residues. We earlier showed that a bacterially expressed peptide, designated as NE2, located from amino acid residues 394 to 606 of ORF2, was found to aggregate into homodimer to at least hexamer. To understand the interface domains within this peptide vital for dimerization and formation of major neutralizing epitopes, NE2 protein underwent terminal-truncated and site-directed mutation. The hydrophobic region, ORF2 aa597-aa602 (AVAVLA), played a key role in oligomerization. Any amino acid residue of this region replaced with glutamic acid residue, the peptide can not refold as homodimer and/or oligomer. The immunoreactivities of these mutant peptides, blotted with anti-HEV neutralizing monoclonal antibody (8C11) and convalescent human sera, show associated to the formation of homodimer. The intermolecular contact region on homodimer was investigated by chemical cross-linking of two site-directed cysteines. When the alanine on aa597 site mutated with cysteine, two different homodimers were found in SDS-PAGE analysis. One (42kD) can be disassociated with 8mol/L urea, which is postulated to form by virtue of hydrophobic interaction, and the other (60kD) falls apart with the reductant DTT present. The exact conformation, generating the cross-linking reaction of cysteines, was further investigated by induced-oxidation on monomer and hydrophobic homodimer of A597C protein with GSH/GSSG. And the results revealed, it is the conformation of hydrophobic homodimer that induces the disulfide bond come into being, instead of the one of monomer. So the aa597 site was verified to be located on interface domain of hydrophobically interacting homodimeric complex. To evaluate the biological significance of hydrophobicity of interface domain, we searched natural variations as to the region on all available databases with NCBI blast program. All variations on these amino acid residues kept higher hydrophobicity, which suggests that the hydrophobic domain is critical for the assemblage and propagation of HEV. NE2 N-terminal deletions up to aa458 had no effect on dimerization and took no exact part in formation of major neutralizing epitopes, but the fragment may act as helper for the formation of major neutralizing epitopes on NE2. Interestingly, the C-terminus aa605-aa660 of ORF2 can also act as helper instead of the N-terminus of NE2. This study suggests an interface domain of NE2 might be vital for HEV capsomer assembly and formation of major neutralizing epitopes. These results may offer clues to the rational design of recombinant anti-HEV vaccine.

Capsid Proteins↗

PubMed2004

[Expression of serum hepatocyte growth factor in patients with acute renal failure].

OBJECTIVE: To investigate the changes of serum hepatocyte growth factor (HGF) in patients with acute renal failure (ARF) and to evaluate the clinical value. METHODS: Serum HGF levels were determined by ELISA in 31 patients with ARF at the stages of oliguria, polyuria and convalescence and in 28 healthy controls. RESULTS: Compared with the controls, the HGF levels in the serum increased significantly in the ARF group at the stages of oliguria and polyuria, while the serum HGF returned to normal levels at the convalescence stage. There was significant positive correlation between the serum HGF and BUN or SCr in the ARF group. CONCLUSION: Serum HGF in ARF patients increased significantly and tended to rise at first but dropped afterwards, which reflected the course of renal injury and the recovery of renal epithelial cells.

Acute Kidney Injury↗

PubMed2004

[Effects of 1-(3-fluorophenyl)-5-methyl-2-(1H)-pyridone on renal fibroblast in rats].

OBJECTIVE: To explore the curative effects of 1-(3-fluorophenyl)-5-methyl-2- (1H)-pyridone (FMP) on renal fibrosis in rats. METHODS: The effects of FMP on the cell proliferation and Fn secretion were measured by methyl thiazolyl tetrazolium and enzyme-linked immunoabsorbent assay, respectively. RESULTS: FMP obviously inhibited the proliferation and Fn secretion in rat renal fibroblast 48 hours after the treatment. FMP (1 000 microg/ml) obviously inhibited the proliferation of rat renal fibroblast 24 hours after the treatment. CONCLUSION: 1-(3-Fluorophenyl) -5-methyl-2-(1H)-pyridone can obviously inhibit the proliferation of rat renal fibroblast, which may be effective for renal interstitial fibrosis prevention and treatment.

Animals↗

PubMed2003

[Use of biopsy results to predict capsular perforation and seminal vesicle invasion in prostate cancer].

OBJECTIVE: To determine the ability of clinical tests to predict extraprostatic cxtension and seminal vesicle invasion. METHODS: Clinical T stage, TPSA total prostate specific antigen and pathologic features in systematic biopsy specimens were correlated with pathologic stage in 40 consecutive patients with clinically localized prostate cancer detected by systematic needle biopsies and treated with radical prostatectomy. RESULTS: Extraprostatic extension was observed in 20 patients (50%) and seminal vesicle invasion was noted in 11(28%). Preoperative variables predictors of extraprostatic extension and seminal vesicle invasion on univariate analysis were TPSA, Gleason score, the total length of cancer, the number of positive cores, the percentage of positive cores, the maximum length of cancer in any one core in the biopsy specimen and the percentage of cancer in the biopsy set P<0.05 . In multivariate analysis, TPSA, Gleason score, the total length of cancer and the percentage of positive cores in the biopsy specimens were the only significant predictors of extraprostatic extension and seminal vesicle invasion P<0.01 . A model was constructed to predict advanced stage: the TPSA >or=11 microg x L(-1) and Gleason score/5 and percentage of positive cores in the biopsy specimen >or=27% or the total length of cancer>or=7.3 mm P<0.001 . CONCLUSION: The combination of TPSA, the total length of cancer, Gleason score and percentage of positive cores in the biopsy specimens provides the best prediction of capsular perforation and seminal vesicle invasion. Models based on this combination of factors may be clinically useful to stratify patients for nonoperative treatment.

Aged↗

PubMed2003

The extracellular matrix protein mindin is a pattern-recognition molecule for microbial pathogens.

Microbial pathogens use a variety of their surface molecules to bind to host extracellular matrix (ECM) components to establish an effective infection. However, ECM components can also serve as an integral part of the innate immunity. Mice lacking expression of mindin (spondin 2), a highly conserved ECM protein, have an impaired ability to clear bacterial infection, and mindin-deficient macrophages show defective responses to a broad spectrum of microbial stimuli. Moreover, mindin binds directly to bacteria and their components and functions as an opsonin for macrophage phagocytosis of bacteria. Thus, mindin is essential in the initiation of the innate immune response and represents a unique pattern-recognition molecule in the ECM for microbial pathogens.

Amino Acid Sequence↗

PubMed2003

The Caenorhabditis elegans cathepsin Z-like cysteine protease, Ce-CPZ-1, has a multifunctional role during the worms' development.

We have analyzed the expression and function of Cecpz-1, a Caenorhabditis elegans cathepsin Z-like cysteine protease gene, during development of the worm. The cpz-1 gene is expressed in various hypodermal cells of all developmental stages and is specifically expressed in the gonads and the pharynx of adult worms. Disruption of cpz-1 function by RNA interference or cpz-1(ok497) deletion mutant suggests that cpz-1 has a role in the molting pathways. The presence of the native CPZ-1 protein in the hypodermis/cuticle of larval and adult stages and along the length of the pharynx of adult worms, as well as the cyclic expression of the transcript during larval development, supports such function. We hypothesize that the CPZ-1 enzyme functions directly as a proteolytic enzyme degrading cuticular proteins before ecdysis and/or indirectly by processing other proteins such as proenzymes and/or other proteins that have an essential role during molting. Notably, an impressive level of the CPZ-1 native protein is present in both the new and the old cuticles during larval molting, in particular in the regions that are degraded prior to shedding and ecdysis. The similar localization of the related Onchocerca volvulus cathepsin Z protein suggests that the function of CPZ-1 during molting might be conserved in other nematodes. Based on the cpz-1 RNA interference and cpz-1 (ok497) deletion mutant phenotypes, it appears that cpz-1 have additional roles during morphogenesis. Deletion of cpz-1 coding sequence or inhibition of cpz-1 function by RNA interference also caused morphological defects in the head or tail region of larvae, improperly developed gonad in adult worms and embryonic lethality. The CPZ-1 native protein in these affected regions may have a role in the cuticular and the basement membrane extracellular matrix assembly process. The present findings have defined a critical role for cathepsin Z in nematode biology.

Amino Acid Sequence↗

PubMed2003

Death decoy receptor TR6/DcR3 inhibits T cell chemotaxis in vitro and in vivo.

TR6/DcR3 is a secreted molecule belonging to the TNFR family. Its ligands are LIGHT, Fas ligand, and TL1A, all TNF family members. TR6 is expressed in some tumors and is hypothesized to endow tumor cells with survival advantages by blocking Fas-mediated apoptosis. It can also inhibit T cell activation by interfering with two-way T cell costimulation between LIGHT and HveA. In this study, we discovered a novel function of TR6: inhibition of T cell chemotaxis. Human T cells pretreated with soluble or solid-phase TR6-Fc showed compromised migration toward CXCL12/stromal cell-derived factor 1alpha in vitro in a Transwell assay. Such an effect could also be observed in T cells pretreated with soluble or solid-phase HveA-Fc or anti-LIGHT mAb, suggesting that LIGHT reverse signaling was likely responsible for chemotaxis inhibition. TR6 pretreatment also led to T cell chemotaxis suppression in vivo in the mice, confirming in vivo relevance of the in vitro observation. Mechanistically, a small GTPase Cdc42 failed to be activated after TR6 pretreatment of human T cells, and further downstream, p38 mitogen-activated protein kinase activation, actin polymerization, and pseudopodium formation were all down-regulated in the treated T cells. This study revealed a previously unknown function of TR6 in immune regulation, and such an effect could conceivably be explored for therapeutic use in controlling undesirable immune responses.

Actins↗

PubMed2003

Neonatal gene transfer with a retroviral vector results in tolerance to human factor IX in mice and dogs.

The effect of neonatal gene transfer on antibody formation was determined using a retroviral vector (RV) expressing human factor IX (hFIX). Normal mice from different strains injected intravenously with RV as newborns achieved therapeutic levels of hFIX without antibody production and were tolerant as adults to challenge with hFIX. Neonatal hemophilia B mice that received different amounts of RV achieved stable and dose-related expression of hFIX without anti-hFIX antibody formation. After protein challenge, antibody formation was markedly reduced for animals that expressed hFIX at levels higher than 14 ng/mL (0.3% of normal). However, antibodies developed for animals that received the lowest dose of RV and expressed hFIX at approximately 2 ng/mL before protein challenge. In dogs, neonatal injection of a high dose of RV resulted in 500 ng/mL hFIX in plasma without antibody formation. We conclude that neonatal gene transfer with RV does not induce antibody responses to hFIX in mice or dogs and that mice achieving levels greater than 3 x 10-10 M hFIX are usually tolerant to protein injection as adults. Low-dose gene therapy or frequent protein injections in the neonatal period might induce tolerance to subsequent injections of protein with a low risk for adverse effects.

Animals↗

PubMed2003

The cell death regulator GRIM-19 is an inhibitor of signal transducer and activator of transcription 3.

GRIM-19 (gene associated with retinoid-IFN-induced mortality 19), isolated as a cell death activator in a genetic screen used to define mechanisms involved in IFN-beta- and retinoic acid-induced cell death, codes for a approximately 16-kDa protein that induces apoptosis in a number of cell lines. Antisense ablation of GRIM-19 caused resistance to cell death induced by IFN plus retinoic acid and conferred a growth advantage to cells. To understand the molecular bases for its cell death regulatory activity, we used a yeast two-hybrid screen and identified that the transcription factor STAT3 (signal transducer and activator of transcription 3) binds to GRIM-19. GRIM-19 inhibits transcription driven by activation of STAT3, but not STAT1. It neither inhibits the ligand-induced activation of STAT3 nor blocks its ability to bind to DNA. Mutational analysis indicates that the transactivation domain of STAT3, especially residue S727, is required for GRIM-19 binding. Because GRIM-19 does not bind significantly to other STATs, our studies identify a specific inhibitor of STAT3. Because constitutively active STAT3 up-regulates antiapoptotic genes to promote tumor survival, its inhibition by GRIM-19 also demonstrates an antioncogenic effect exerted by biological therapeutics.

Animals↗

PubMed2003

Exact two-qubit universal quantum circuit.

We provide an analytic way to implement any arbitrary two-qubit unitary operation, given an entangling two-qubit gate together with local gates. This is shown to provide explicit construction of a universal quantum circuit that exactly simulates arbitrary two-qubit operations in SU(4). Each block in this circuit is given in a closed form solution. We also provide a uniform upper bound of the applications of the given entangling gates, and find that exactly half of all the controlled-unitary gates satisfy the same upper bound as the CNOT gate. These results allow for the efficient implementation of operations in SU(4) required for both quantum computation and quantum simulation.

Journal Article↗

PubMed2003

Clinical significance of detecting elevated serum DcR3/TR6/M68 in malignant tumor patients.

TR6/DcR3/M68 is a soluble receptor that belongs to the TNF receptor family. It is expressed in malignant cells of several tumor types and has been postulated to help tumor cells to gain survival advantage by inhibiting apoptosis and by interfering with immune surveillance. In our study, we assessed for the first time serum TR6 in tumor patients to explore its diagnostic and prognostic value. We examined serum TR6 levels with ELISA in 146 tumor patients, 19 patients with acute infection, 5 patients with liver cirrhosis and 29 healthy individuals. TR6 expression in tumor mass was studied with immunohistochemistry. TR6 gene copy number in tumor tissues was evaluated by real time PCR. Ninety-seven point nine percent (47 of 48 cases) of healthy individuals and patients with acute infection were serum TR6-negative. In contrast, 56.2% (82 of 146 cases) of the tumor patients were serum TR6-positive. Almost all serum TR6-positive individuals (98.8%, 82 out of 83 cases) had malignancy, excluding the cases of liver cirrhosis. In gastric carcinomas, serum TR6 levels were closely correlated with tumor differentiation status and TNM classification. Tumor mass was the source of serum TR6 because its levels decreased drastically after curative tumor resection. TR6 gene amplification occurred in about half of liver carcinomas, but not in gastric or pancreatic carcinomas, indicating plural mechanisms of TR6 upregulation. Our study demonstrated that serum TR6 should be considered as a novel parameter for the diagnosis, treatment and prognosis of malignancies.

Adenocarcinoma, Follicular↗

PubMed2003

Cardioprotection involves activation of NF-kappa B via PKC-dependent tyrosine and serine phosphorylation of I kappa B-alpha.

Previous studies indicated that activation of PKC and Src tyrosine kinases by ischemic preconditioning (PC) may participate in the activation of NF-kappa B. However, the molecular mechanisms underlying activation of NF-kappa B during ischemic PC remain unknown. In the hearts of conscious rabbits, it was found that ischemic PC (6 cycles of 4-min coronary occlusion and 4-min reperfusion) significantly induced both tyrosine (+226.9 +/- 42%) and serine (+137.0 +/- 36%) phosphorylation of the NF-kappa B inhibitory protein I kappa B-alpha, concomitant with increased activation of the I kappa B-alpha kinases IKK alpha (+255.0 +/- 46%) and IKK beta (+173.1 +/- 35%). Furthermore, both tyrosine and serine phosphorylation of I kappa B-alpha were blocked by pretreatment with either the nonreceptor tyrosine kinase inhibitor lavendustin-A (LD-A) or the PKC inhibitor chelerythrine (Che) (both given at doses previously shown to block ischemic PC). Interestingly, Che completely abolished PC-induced activation of IKK alpha/beta, whereas LD-A had no effect. In addition, I kappa B-alpha protein level did not change during ischemic PC. Together, these data indicate that ischemic PC-induced activation of NF-kappa B occurs through both tyrosine and serine phosphorylation of I kappa B-alpha and is regulated by nonreceptor tyrosine kinases and PKC.

Animals↗

PubMed2003

Cervical cerclage in delayed interval delivery in a multifetal pregnancy: a review of seven case series.

OBJECTIVE: To examine whether cervical cerclage after the first delivery prolongs the inter-delivery interval in delayed interval deliveries. STUDY DESIGN: We identified 66 case reports and case series of delayed interval delivery published between 1880 and 2002. We selected seven case series that identified all cases of delayed interval delivery in their institutions during a specified period. RESULTS: Despite routine use of broad-spectrum prophylactic antibiotics, the average incidence of clinical intrauterine infection after the first delivery was 36% (95% confidence interval (CI): 26-46%). The incidence of maternal sepsis was 4.9% (95% CI: 0.2-9.6%). Studies in which cerclage was infrequently used reported a shorter inter-delivery interval compared to studies where cerclage was used in all cases (median is equal to 9 days versus 26 days, respectively, P<0.001) despite similar gestational ages at the first delivery, types of antibiotics, tocolytics, and incidence of infection. After controlling for other factors, the use of cerclage did not significantly increase the risk of intrauterine infection (adjusted relative risk=1.1, 95% CI: 0.4-3.5). CONCLUSION: Cervical cerclage after the first delivery is associated with a longer inter-delivery interval without increasing the risk of intrauterine infection.

Cerclage, Cervical↗

PubMed2003

DcR3/TR6 modulates immune cell interactions.

DcR3/TR6, a secreted protein, is a member of TNF receptor family. Its ligands include FasL, LIGHT, and TL1A, all TNF family members. TR6 can interfere with FasL- or LTbetaR-mediated apoptosis; it can also inhibit T-cell costimulation by blocking the two-way signaling between TR2 and LIGHT, and the one-way signaling from TL1A to DR3. In this study, we discovered that TR6 was secreted by peripheral blood mononuclear cells (PBMC) stimulated by T-cell mitogens. It inhibited actin polymerization of T cells upon mitogen stimulation, and repress T-cell pseudopodium formation, which is known to be important for cell-cell interaction. As a consequence, T-cell aggregation stimulated by alloantigens, anti-CD3 or PHA was suppressed by either soluble or solid phase TR6-Fc. This result suggests that TR6 might regulate T-cell interaction with other cells such as antigen-presenting cells (APC) or their fellow T cells by preventing them from forming inseparable cell clusters, which are undesirable for the progression of immune responses.

Base Sequence↗

PubMed2003

Evaluation of the Tg.AC assay: specificity testing with three noncarcinogenic pharmaceuticals that induce selected stress gene promoters in vitro and the inhibitory effects of solvent components.

Understanding the strengths and limitations of alternative models, such as the Tg.AC assay, for evaluation of the potential carcinogenicity of pharmaceuticals requires assessment of assay specificity through studies that specifically target biologically active compounds that are known to not be carcinogens in rodents. To identify drugs that might provoke a false positive response in the Tg.AC assay, we screened pharmaceuticals for in vitro induction of the gadd153 promoter and the zeta-globin promoter. We have previously found a high correlation between induction of the gadd153 promoter in HepG2 cells and activity in the Tg.AC assay. The three drugs selected through screening 99 noncarcinogenic pharmaceuticals were amiloride, dipyridamole, and pyrimethamine. A 26-week skin paint study was conducted in hemizygous Tg.AC mice with the three drugs at two doses selected by a 4-week dose range finding study. Evidence of systemic toxicity was observed in animals dosed chronically with pyrimethamine or amiloride, but no skin papillomas were observed in mice treated with amiloride, dipyridamole, or pyrimethamine for 26 weeks. All male mice and 80% of female mice treated with 12-O-tetradecanoylphorbol-13-acetate (TPA) in acetone developed a maximal tumor burden. However, mice treated with TPA in a vehicle containing 2.4% DMSO had greatly reduced incidences of papillomas. In summary, the correct negative response was shown in the Tg.AC assay for three noncarcinogenic pharmaceuticals, which adds further favorable evidence of appropriate specificity of this model system. However, vehicle composition must be carefully selected because the outcome of this assay can be confounded by certain commonly used solvents.

Acetone↗

PubMed2003

Localization of GABAA receptor subunits alpha 1, alpha 3, beta 1, beta 2/3, gamma 1, and gamma 2 in the salamander retina.

Electrophysiological studies have demonstrated that gamma-aminobutyric acid receptors type A (GABA(A)) mediate important information processing in the retinas of salamander and other vertebrates. The pharmacology and physiology of GABA(A) receptors depend on their subunit composition. We studied the localization of GABA(A) receptor subunit isoforms alpha(1), alpha(3), beta(1), beta(2/3) (antibody BD-17 and 62-3G1), gamma(1), and gamma(2) in salamander retina with immunocytochemical methods. All three beta-subunit antibodies labeled similarly in the outer retina, especially the inner segments and synaptic terminals of rod photoreceptors (identified with protein kinase C). Somatic labeling was observed in cell bodies of some horizontal cells, bipolar cells, amacrine cells, and cells in the ganglion cell layer (GCL). Puncta were present throughout the inner plexiform layer (IPL) for beta(1) and 62-3G1, but not for BD-17. alpha(1)-immunoreactivity (IR) stained a population of presumed OFF rod-dominated bipolar cells, including dendrites, soma, and axon terminals in the distal IPL. A subtype of GABAergic amacrine cell also expressed alpha(1)-IR, with puncta sparsely distributed at the distal and proximal margins of the IPL. Both the OPL and IPL were labeled throughout for alpha(3)-IR, as opposed to the narrow distribution of alpha(1)-IR in the IPL, suggesting that the two alpha-subunits are localized at different synaptic sites. Punctate gamma(1)-IR was observed in the OPL and IPL, whereas gamma(2) was most prominent in cone photoreceptors (identified with calbindin), including the terminal telodendria, in cell bodies of some horizontal cells, amacrine cells, cells in the GCL, and less intensely in the IPL. In addition, several subunits were present in Müller cells. The differential labeling suggests the existence of GABA(A) receptor subtypes with different subunit compositions that mediate multiple GABAergic functions in salamander retina.

Ambystoma↗

PubMed2003

Molecular characterization of circulating EBV DNA in the plasma of nasopharyngeal carcinoma and lymphoma patients.

Despite the increasing clinical applications of circulating EBV DNA analysis as a tumor marker, the molecular nature of these EBV DNA molecules remains unclear. We subjected plasma/serum samples of nasopharyngeal carcinoma and lymphoma patients to DNase digestion and ultracentrifugation and showed that circulating EBV DNA molecules are "naked" DNA fragments instead of being contained inside virions. We further showed that these EBV DNA fragments were relatively short, and 87% of them were shorter than 181 bp. These results provide fundamental information that may improve our understanding of the release of tumor-derived nucleic acids into the blood of cancer patients.

DNA, Viral↗