Biomedical subjects

Z Qi

Publications and source records attributed to Z Qi.

At least 55 records · Page 3Linked to original sources

PubMed2000

[Retroviral-mediated high efficient in vitro expression of human coagulation factor VIII].

OBJECTIVE: To develop a retroviral-mediated high efficient expression system of human coagulation factor VIII. METHODS: The retroviral vector LNC-VIIIBD was generated by cloning a B-domain-deleted FVIII cDNA (760aa - 1639aa) into retroviral vector pLNCX. Several cell lines including NIH3T3, CHO, COS-7 and human hepatic cell line L-02 were infected with viral supernatant from the highest productive PA317 clones. The antigen and procoagulant activity of human FVIII in the cell culture medium were measured by ELISA assay and one-stage method, respectively. RT-PCR was performed for the detection of F VIII BD mRNA. RESULTS: Human FVIII was expressed in all four target cells. The highest expression was observed in NIH3T3, the procoagulant activity of secreted FVIII was up to 1.6 U, and the FVIII antigen was 500 ng by 10(6) cells/ml in 24 hours, respectively. CONCLUSION: The constructed retroviral vector was able to generate high level expression of human FVIII in some cell lines, and it might have potential utility in the gene therapy for Hemophilia A.

3T3 Cells↗

PubMed2000

[The influences of human apolipoprotein E mutants on the learning and memory of cerebral cortex in transgenic mice].

OBJECTIVE: To study the influences of the mutants of human apolipoprotein E on the function of cerebral cortex. METHODS: The Southern blot hybridization and ELISA techniques were used for identification of integration and expression of human apoE4 and apoE7 genes at the mice chromosome and in the serum of F1 transgenic mice. Then the active avoidance response test was performed to determine the alteration of learning and short term and long term memory of the transgenic mice. The serum total cholesterol (TC) and triglyceride (TG) were determined simultaneously with enzymatic procedure. RESULTS: (1) In F1 transgenic mice the human apoE genes integrated at the chromosome and expressed in their serum stably. (2) In apoE4 mice the learning and short term memorizing abilities were decreased, and in apoE7 mice the short term memorizing abilities were decreased as well. In addition, the TC and TG increased statistically. CONCLUSIONS: The overexpression of human apoE4 and apoE7 genes in transgenic mice could damage the function of cerebral cortex. It denoted that the mutations of apoE might correlate the pathogenesis of Alzheimer's disease.

Animals↗

PubMed2000

[Transgenic mice model of human hepatitis B virus x gene].

OBJECTIVE: To set up a human hepatitis B virus x (HBx) gene transgenic model. METHODS: The model was set up by microinjection, the integration and expression of the founders were identified by molecular hybridization. RESULTS: A 1,800 bp DNA fragment containing the human HBx promoter and genomic DNA was microinjected into the male pronucleus of the fertilized eggs of mice. Three hundred and thirty-eight eggs survived from microinjection were transplanted into the oviduct of 16 pseudopregnant female, 12 pseudopregnant mice got pregnant and gave birth to 74 pups. Genomic DNA were extracted from the tails of the pups, Southern blot hybridization was used for determination of the integration of human HBx gene. The 1,800 bp microinjected fragment was used as the probe, 17 mice (founders) were identified of the integration of human HBx gene. Total RNA were extracted from the livers of the founders, all 17 founders were identified of the expression of human HBx gene by using Northern blot hybridization. CONCLUSIONS: These results may provide animal models for studying on the correlation between chronic HBV infection and the development of hepatocellular carcinoma.

Animals↗

PubMed1999

Accelerated diffusion of Na(+) in a hydrophobic region revealed by molecular dynamics simulations of a synthetic ion channel.

To get insight into the significance of the hydrophobic lining on the ion permeation, we performed molecular dynamics simulations on a Na(+) permeation through a de novo synthetic hydrophobic channel. Electrophysiological study has suggested that the channel is formed from a tail-to-tail associated dimer of a cyclic octa-peptide coupled with hydrophobic acyl chains. The acyl chains line the channel pore while the cyclic peptide forms the channel entrance [Z. Qi, M. Sokabe, K. Donowaki, H. Ishida, Biophys. J. 76 (1999) 631]. Molecular dynamics simulation of water in the channel indicated that the inferred structure is physically reasonable [Z. Qi, M. Sokabe, Biophys. Chem. 71 (1998) 35]. In the present study, the potential energy profile of the Na(+) and the energy contributions from each component of the system at different positions along the channel axis were calculated. An energy well instead of a peak is located at the central hydrophobic cavity of the channel, due to its ability of accommodating at least five water molecules to hydrate the ion. Interestingly, the ion diffuses much faster in the hydrophobic acyl chain region, particularly in the central hydrophobic cavity, than it does in the peptide ring region and even surprisingly faster than that in the bulk phase. These results provide a physical basis for an idea that the hydrophobic lining of the K(+) channel [D.A. Doyle, J.M. Cabral, R.A. Pfuetzner, A. Kuo, J.M. Gulbis, S.L. Cohen, B.T. Chait, R. MacKinnon, Science 280 (1998) 69] plays an active role to facilitate the ion permeation through the channel pore.

Journal Article↗

PubMed1999

Heme is an effector molecule for iron-dependent degradation of the bacterial iron response regulator (Irr) protein.

The bacterial iron response regulator (Irr) protein mediates iron-dependent regulation of heme biosynthesis. Pulse-chase and immunoprecipitation experiments showed that Irr degraded in response to 6 microM iron with a half-life of approximately 30 min and that this regulated stability was the principal determinant of control by iron. Irr contains a heme regulatory motif (HRM) near its amino terminus. A role for heme in regulation was implicated by the retention of Irr in heme synthesis mutants in the presence of iron. Addition of heme to low iron (0.3 microM) cultures was sufficient for the disappearance of Irr in cells of the wild-type and heme mutant strains. Spectral and binding analyses of purified recombinant Irr showed that the protein bound heme with high affinity and caused a blue shift in the absorption spectrum of heme to a shorter wavelength. A Cys(29) --> Ala substitution within the HRM of Irr (IrrC29A) abrogated both high affinity binding to heme and the spectral blue shift. In vivo turnover experiments showed that, unlike wild-type Irr, IrrC29A was stable in the presence of iron. We conclude that iron-dependent degradation of Irr involves direct binding of heme to the protein at the HRM. The findings implicate a regulatory role for heme in protein degradation and provide direct evidence for a functional HRM in a prokaryote.

Bacterial Proteins↗

PubMed1999

Blockade of type beta transforming growth factor signaling prevents liver fibrosis and dysfunction in the rat.

We eliminated type beta transforming growth factor (TGF-beta) signaling by adenovirus-mediated local expression of a dominant-negative type II TGF-beta receptor (AdCATbeta-TR) in the liver of rats treated with dimethylnitrosamine, a model of persistent liver fibrosis. In rats that received a single application of AdCATbeta-TR via the portal vein, liver fibrosis as assessed by histology and hydroxyproline content was markedly attenuated. All AdCATbeta-TR-treated rats remained alive, and their serum levels of hyaluronic acid and transaminases remained at low levels, whereas all the AdCATbeta-TR-untreated rats died of liver dysfunction. The results demonstrate that TGF-beta does play a central role in liver fibrogenesis and indicate clearly in a persistent fibrosis model that prevention of fibrosis by anti-TGF-beta intervention could be therapeutically useful.

Adenoviridae↗

PubMed1999

Structure-function study on a de novo synthetic hydrophobic ion channel.

Ion conduction properties of a de novo synthesized channel, formed from cyclic octa-peptides consisting of four alternate L-alanine (Ala) and N'-acylated 3-aminobenzoic acid (Aba) moieties, were studied in bilayer membranes. The single-channel conductance was 9 pS in symmetrical 500 mM KCl. The channel favored permeation of cations over anions with a permeability ratio (PCl-/PK+) of 0.15. The selectivity sequence among monovalent cations based on permeability ratio (PX+/PK+) fell into an order: NH4+(1.4) > Cs+(1. 1) >/= K+(1.0) > Na+(0.4) >> Li+(0). The conductance-activity relationship of the channel in K+ solutions followed simple Michaelis-Menten kinetics with a half-maximal saturating activity of 8 mM and a maximal conductance of 9 pS. The permeability ratio PNa+/PK+ remained constant ( approximately 0.40) under biionic concentrations from 10 to 500 mM. These results suggests that the channel is a one-ion channel. The pore diameter probed by a set of organic cations was approximately 6 A. The single-channel current was blocked by Ca2+ in a dose-dependent manner that followed a single-site titration curve with a voltage-dependent dissociation constant of 0.6 mM at 100 mV. The electric distance of the binding site for Ca2+ was 0.07 from both entrances of the channel, indicating the presence of two symmetrical binding sites in each vicinity of the channel entrance. Correlations between conduction properties and structural aspects of the channel are discussed in terms of a three-barrier and two-binding-site (3B2S) model of Eyring rate theory. All available structural information supported an idea that the channel was formed from a tail-to-tail associated dimer of the molecule, the pore of which was lined with hydrophobic acyl chains. This is the first report to have made a systematic analysis of ion permeation through a hydrophobic pore.

Binding Sites↗

PubMed1999

Malononitrilamides and tacrolimus additively prevent acute rejection in rat cardiac allografts.

The novel immunosuppressive agents malononitrilamides (MNA) 279 and 715 are derivatives of A77 1726, the primary metabolite of leflunomide. The effects of these agents have been previously demonstrated in rat skin and cardiac allo- and xenotransplant models. The aim of this study was to evaluate the combination of MNA and tacrolimus in a high-responder rat cardiac allotransplant model. Graft survival was evaluated following 10 days of post-transplant oral therapy of MNA or tacrolimus alone and the drugs combined in PVG recipients of DA grafts. An iso-effect curve of single and combined drugs was constructed. Histological changes in grafts were evaluated at 10 days. MNA (20 mg/kg) or tacrolimus (2.4 mg/kg) alone prolonged graft survival with median survival of 14 and 13.5 days, respectively. Combined therapy of MNA (10 mg/kg) and tacrolimus 1.6 mg/kg likewise resulted in a median survival of 13.25 days and an iso-effect curve for these doses was constructed. Another iso-effect curve for median graft survival of 18-19 days, including MNA (10 mg/kg) + tacrolimus (3.2 mg/kg) in combination, MNA (30 mg/kg) alone and tacrolimus (4.8 mg/kg) alone, was constructed and both isoboles showed a straight line, demonstrating additive effects (zero interaction). In addition, histological analysis of grafts confirmed the benefit of the drug combination. No additional toxicity was noted with combined therapy. Optimal doses of MNA or tacrolimus had comparative effects on graft survival and histological changes, and a combination of the two drugs was beneficial with respect to both these parameters. The iso-effect curves verified additive effects of the drug combination.

Alkynes↗

PubMed1999

Effective and safe gene therapy for colorectal carcinoma using the cytosine deaminase gene directed by the carcinoembryonic antigen promoter.

We have recently isolated carcinoembryonic antigen (CEA) promoter regions consisting of 419 bp and 204 bp from CEA-producing human colorectal carcinoma (CRC). We constructed CEA419/CD and CEA204/CD retroviruses carrying the bacterial cytosine deaminase (CD) gene directed by the CEA promoter regions. pCD2 retroviruses carrying the CD gene directed by the retrovirus long terminal repeat promoter were also used. CEA419/CD or CEA204/CD retrovirus-infected CRC cells were found to be susceptible to 5-fluorocytosine (5-FC), while non-CRC cells infected with the same retroviruses were not. CD-transduced CRC xenografts in nude mice were sensitive to 5-FC treatment, resulting in arrest of tumor growth. When mice with intraperitoneally disseminated CRCs were given intraperitoneal injections of CEA419/CD retrovirus-producing cells followed by 5-FC treatment, significantly prolonged survival rates were observed compared with animals injected with pCD2 retrovirus-producing cells followed by 5-FC treatment. Importantly, bone marrow suppression was not observed in animals injected with CEA419/CD retrovirus-producing cells and 5-FC, while profound bone marrow suppression was observed in those injected with pCD2 retrovirus-producing cells and 5-FC. These results indicate that effective and safe in vivo gene therapy for advanced CRC may be feasible by transferring the CD gene controlled by the CEA promoter followed by 5-FC treatment.

Animals↗

PubMed1999

Antithymocyte globulin and cyclosporin A are synergistic in an experimental transplantation tolerance model in the rat.

The aim of the present investigation was to study the possible synergistic effect between cyclosporin A (CsA) and antithymocyte globulin (ATG), using the potent immunostimulator, Linomide. DA rats were transplanted with a PVG/c heart to the neck vessels, and the recipients were treated for 10 days with oral CsA (10mg/kg), oral Linomide (160mg/kg) and/or ATG, which was given as a single dose of either 0.02 ml, 0.1 ml or 0.2 ml prior to transplantation. Rats given a combination of ATG and Linomide or CsA and Linomide were used as controls. Synergism between CsA and ATG was tested using the two immunosuppressive drugs given in combination in order to override the challenge of Linomide. CsA or ATG treatment alone resulted in rats with long-term surviving grafts. Addition of Linomide to CsA-treated recipients was followed by early graft rejection. Similarily, Linomide triggered rejection in rats given a low dose of ATG and in recipients given a high dose of ATG if Linomide treatment was prolonged to 21 days. The combination of ATG, CsA and 21 days of Linomide resulted in a significantly prolonged graft survival compared with either ATG + Linomide or CsA + Linomide. These findings demonstrate the synergistic capacity of ATG and CsA in combined immunosuppressive therapy.

Adjuvants, Immunologic↗

PubMed1999

Tolerance or rejection: A delicate balance as judged by exposure of heart-transplanted rats to the immunomodulator Linomide.

When applied in rodent transplant models most immunosuppressive drugs yield adequate graft protection for as long as the drug is given, and permanent graft survival is often induced. The immunomodulator, Linomide, previously shown to stimulate T cells and prevent apoptosis, usually reduces or abolishes both tolerance induction and the graft-protective effect of the immunosuppressive drug. By chance, we observed that Linomide alone exerted a modest but unequivocal graft-protective effect in the BN to WF strain combination. This finding was analysed by simple genetic mapping of rat strains. Untreated WF recipients kept BN grafts for a median of 8 days, whereas Linomide treatment prolonged graft survival to 12. 5 days (P = 0.0001). In control groups (DA to LEW, BN to LEW, DA to WF and WF to BN), median graft survival was 5.5-7 days irrespective of whether Linomide was given. However, the BN to F1 (LEW x WF) combination also manifested slightly longer graft survival in the presence of Linomide. F1 (BN x WF) to WF grafts survived a median of 15 days without Linomide and 46 days with Linomide treatment. Both in the presence and absence of Linomide, two of the control graft combinations [F1 (BN x DA) to WF and F1 (BN x WF) to BN] manifested 6-7-day graft survival. Taken together, our results suggest a delicate balance between unresponsiveness and rejection, while a single agent (Linomide) may either cause on its own long-term survival of allografts in one setting or rejection despite optimal immunosuppression in another setting.

Adjuvants, Immunologic↗

PubMed1999

Potassium uptake supporting plant growth in the absence of AKT1 channel activity: Inhibition by ammonium and stimulation by sodium.

A transferred-DNA insertion mutant of Arabidopsis that lacks AKT1 inward-rectifying K+ channel activity in root cells was obtained previously by a reverse-genetic strategy, enabling a dissection of the K+-uptake apparatus of the root into AKT1 and non-AKT1 components. Membrane potential measurements in root cells demonstrated that the AKT1 component of the wild-type K+ permeability was between 55 and 63% when external [K+] was between 10 and 1,000 microM, and NH4+ was absent. NH4+ specifically inhibited the non-AKT1 component, apparently by competing for K+ binding sites on the transporter(s). This inhibition by NH4+ had significant consequences for akt1 plants: K+ permeability, 86Rb+ fluxes into roots, seed germination, and seedling growth rate of the mutant were each similarly inhibited by NH4+. Wild-type plants were much more resistant to NH4+. Thus, AKT1 channels conduct the K+ influx necessary for the growth of Arabidopsis embryos and seedlings in conditions that block the non-AKT1 mechanism. In contrast to the effects of NH4+, Na+ and H+ significantly stimulated the non-AKT1 portion of the K+ permeability. Stimulation of akt1 growth rate by Na+, a predicted consequence of the previous result, was observed when external [K+] was 10 microM. Collectively, these results indicate that the AKT1 channel is an important component of the K+ uptake apparatus supporting growth, even in the "high-affinity" range of K+ concentrations. In the absence of AKT1 channel activity, an NH4+-sensitive, Na+/H+-stimulated mechanism can suffice.

Arabidopsis↗

PubMed1999

Type II cAMP-dependent protein kinase regulates electrogenic ion transport in rabbit collecting duct.

cAMP mediates many of the effects of vasopressin, prostaglandin E2, and beta-adrenergic agents upon salt and water transport in the renal collecting duct. The present studies examined the role of cAMP-dependent protein kinase (PKA) in mediating these effects. PKA is a heterotetramer comprised of two regulatory (R) subunits and two catalytic (C) subunits. The four PKA isoforms may be distinguished by their R subunits that have been designated RIalpha, RIbeta, RIIalpha, and RIIbeta. Three regulatory subunits, RIalpha, RIIalpha, and RIIbeta, were detected by immunoblot and ribonuclease protection in both primary cultures and fresh isolates of rabbit cortical collecting ducts (CCDs). Monolayers of cultured CCDs grown on semipermeable supports were mounted in an Ussing chamber, and combinations of cAMP analogs that selectively activate PKA type I vs. PKA type II were tested for their effect on electrogenic ion transport. Short-circuit current (Isc) was significantly increased by the PKA type II-selective analog pairs N6-monobutyryl-cAMP plus 8-(4-chlorophenylthio)-cAMP or N6-monobutyryl-cAMP plus 8-chloro-cAMP. In contrast the PKA type I-selective cAMP analog pair [N6-monobutyryl-cAMP plus 8-(6-aminohexyl)-amino-cAMP] had no effect on Isc. These results suggest PKA type II is the major isozyme regulating electrogenic ion transport in the rabbit collecting duct.

Animals↗

PubMed1999

Influence of chronic treatment with imipramine on mRNA levels in rat brain: elevation of glyceraldehyde-3-phosphate dehydrogenase levels.

The differential display method was used to identify the intrinsic factor that changes its mRNA expression level in rat brain after a 14-day oral administration of 20 mg/kg imipramine. The expression of a 180-bp band was markedly enhanced by imipramine. The results of sequencing and a data base search revealed that the isolated clone was glyceraldehyde-3-phosphate dehydrogenase (GAPDH) with a one-base difference. Enhancement of the expression by imipramine was observed in the amygdala. Quantitative PCR showed that imipramine treatment significantly elevated the GAPDH/beta-actin ratio in the cortex. These findings suggest that long-term treatment with imipramine stimulates GAPDH mRNA expression.

Adrenergic Uptake Inhibitors↗

PubMed1999

In vivo gene transfer of a suicide gene under the transcriptional control of the carcinoembryonic antigen promoter results in bone marrow transduction but can avoid bone marrow suppression.

We constructed the CEA419/CD retrovirus vector carrying the cytosine deaminase (CD) gene directed by the carcinoembryonic antigen (CEA) promoter. pCD2 retrovirus vector carrying the CD gene directed by the retrovirus long terminal repeat promoter was also used. When mice bearing intraperitoneally disseminated colorectal carcinomas (CRCs) were infused intraperitoneally with pCD2 or CEA419/CD retrovirus-producing cells, a CD fragment was detected in CRCs and bone marrow cells. It was shown that the CD gene was expressed both in CRCs and in the bone marrow of animals infused with pCD2 retrovirus-producing cells, while the CD gene was expressed solely in CRCs of animals infused with CEA419/CD retrovirus-producing cells. These results indicate that the use of a tumor-selective promoter may warrant the safety of in vivo gene therapy using suicide genes.

Adenocarcinoma↗

PubMed1999

[Effect of space environment on physiological state in Carthamus tinctorius L].

OBJECTIVE: To substantiate te effect of weightlessness and heavy ion radiation in space environment on medicinal plants. METHODS: The seeds of medicinal plant Carthamus tinctorius were carried aboard a retrievable satellite during 3-18 July, 1994. After returning to earth, the changes of peroxidase and protein were studied by means of electrophoresis. RESULTS: The result showed that the peroxidase activity of each group of seeds which were hit and penetrated by heavy ions rays was higher than that of the ground controlled seeds, but slightly lower than that of the weightless seeds. The protein contents of the weightless seeds and the seeds which is penetrated once and less than once by heavy ions rays were higher than those of the seeds which were kept on earth, but the seeds which were penetrated 2-3 times by heavy ion rays were lower than those of the ground controlled seeds. The peroxidase isozyme and protein patterns of the weightless seeds were similar to those of the ground controlled seeds, but very different between the heavy ion ray penetrated seeds and the earth kept seeds. CONCLUSION: It follows that the weightlessness in space environment has an effect mainly on the physiological condition of plants, but the heavy ion radiation has a stronger effect on the hereditary basis of plants.

China↗

PubMed1999

[Experimental study on induction of apoptosis of leukemic cells by Boswellia carterii Birdw extractive].

The purpose of the study was to investigate the apoptosis of leukemic cells induced by Boswellia Carterii Birdw(BCB). The target leukemia cell line HL60 and bone marrow leukemic cells from 30 acute non-lymphocytic leukemic(ANLL) patients (3 M1 11 M2a 10 M3 1 M4a 5 M5b) were studied. Apoptosis was detected by morphological observation, DNA electrophoresis, percentage of DNA fragmentation test and flow cytometric cell cycle analysis. It is concluded that BCB can induce apoptosis in ANLL cells and HL60 cells.

Adolescent↗

PubMed1999

[Measurement of soluble Fas in patients with hematological malignancy].

We measured serum levels of soluble Fas(sFas) in 68 patients with hematological malignancy by using sandwich ELISA and detected bone marrow mononuclear cell membrane Fas(mFas) positive cells in 46 patients with acute leukemias by immunohistochemical technic. It was found that sFas levels were significantly higher in acute lymphoblastic leukemia(ALL) patients(median 10.48 +/- 5.89 ng.ml-1) and non-Hodgkin's lymphoma(NHL) patients(median 18.26 +/- 16.47 ng.ml-1) than those in healthy donors (median 0.92 +/- 0.88 ng.ml-1) (P < 0.05). Elevated sFas levels were correlated with the disease stage and progress, but not with other clinical parameters. According to the follow-up of five ALL patients, their serum sFas levels decreased after complete remissions. We conclude that sFas has prognostic value and is an effective clinical parameter with ALL or NHL patients. In addition, sFas levels in the sera of acute non-lymphoblastic leukemia patients were also found to be unchanged compared with those in the normal control.

Adolescent↗