Biomedical subjects

T Zhou

Publications and source records attributed to T Zhou.

At least 55 records · Page 3Linked to original sources

PubMed2001

[Cytotoxic T lymphocyte activity induced by genetic immunization with NV-HC/NS].

OBJECTIVE: To investigate the immunoprophylactic and immunotherapeutic effects of DNA vaccine (NV-HC/NS(3)) after inoculation of mice by target tumor loading technique. METHODS: Before or after inoculation with NV-HC/NS(3) intramuscularly, BALB/c mice in the experimental group were planted with target tumor cells (SP2/0-NS(3)), which were derived from BALB/c mice and stably transfected with the recombinant plasmid NV-HC/NS(3). Tumor growth and survival rate of the mice immunized with NV-HC/NS(3) were compared with those in the control group. RESULTS: Tumor mass grew well in all mice in the control group in a few days, while no visible tumor mass growth in 40% mice immunized with NV-HC/NS(3) could be seen. The survival rate and life span of mice in the experimental group were significantly longer than those in the control group. CONCLUSIONS: Specific immune activity could be induced by immunization with NV-HC/NS(3). Such effects are immunoprophylactic and immunotherapeutic.

Animals↗

PubMed2001

[The package and identifying of hNT-3 recombinated retroviral vector].

hNT-3 was inserted into retroviral vector pLXSN to get pLXSN-NT3, and it was transfected into packaging cell line PA317 to form G418 resistant cell clones. The G418 resistant clones were titered and checked for the existence of replication viral. Genome DNA isolated from the cell clone of highest titeration showed the function gene, hNT-3 cDNA, had integrated into the genome of host cells verified by PCR. And bioassay of the clone's cell culture supernant exhibited that it can induce neurite over-growth in the primary culatures of rat spinal cord dorsal root ganglions as compared with controls.

Animals↗

PubMed2001

Vitamin D receptor gene polymorphism and bone mineral density in patients with type 2 diabetes mellitus.

OBJECTIVE: To explore the relationship between vitamin D receptor (VDR) gene polymorphisms and bone mineral density (BMD) in patients with type 2 diabetes mellitus (DM) and to better understand the pathogenesis of osteoporosis. METHODS: Ninety seven patients with type 2 DM were recruited for this study. BMD was measured by single photon absorptiometry at the lower one third of the nondominant radius and ulna. Polymorphisms of the VDR gene were analyzed by DNA amplification with polymerase chain reaction (PCR) and endonuclease digestion with Bsm I. RESULTS: The respective frequencies of VDR genotypes were BB 18.6%, Bb 27.8% and bb 53.6%. The Z scores of the three groups were -1.57 +/- -0.60, -1.45 +/- -0.67 and -1.41 +/- -0.81, respectively. Although the BMD of the Bb genotype DM patients was higher than that of BB genotype DM patients and lower than that of bb genotype DM patients, there were no significant differences. CONCLUSION: These findings suggest a small influence of VDR gene polymorphism on the BMD of patients with type 2 DM. Further study on the value of VDR genotypes in the pathogenesis of osteoporosis in diabetes mellitus is still needed.

Adult↗

PubMed2001

[Detecting human papillomavirus type 6/11 with fluorescence quantitative PCR].

BACKGROUND: To study the human paillomavirus type 6/11 (HPV6/11) infectious status of patients with vaginitis. METHODS: Fluorescence quantitative PCR (FQ-PCR) was used to measue HPV 6/11 DNA in 129 secretion samples. RESULTS: 47 samples were positive with a positive rate of 36.43%; 39 of 47 samples had over 105 copy/ml of the virus. CONCLUSIONS: Middle and old aged patients do not go to hospital until their virus infectious state becomes serious. FQ-PCR is suitable for clinical application because of its high sensitivity, rapidity and accuracy.

Adult↗

PubMed2001

[A study of the acting mechanism of aspirin for resistance to oxidative damage].

OBJECTIVE: To explore the mechanism of aspirin for resistance to oxidative damage in endothelial cells. METHODS: Using cultured endothelial cells, we measured the levels of aspirin induced ferritin expression on resistance to hydrogen peroxide toxicity toward cells in the presence of the iron chelator desferrioxamine added to FeCl3. RESULTS: Aspirin at low concentration (0.1 mmol/L) induced significant increase of ferritin expression in a time- and concentration-dependent fashion up to 25% over basal levels(P < 0.05). Preincubating the cells for 8 h with aspirin (0.1 mmol/L) reduced lactate dehydrogenase(LDH) release rate by 50%, toxicity reduction by 40%, and significant decrease of malondialdehyde (MDA) production. Aspirin induced cytoprotection from H2O2 damage was also in a concentration- and time-dependent fashion. However, in the presence of the iron chelator desferrioxamine, aspirin enhanced ferritin synthesis was abrogated, in contrast, FeCl3 increased aspirin induced ferritin synthesis in cells. CONCLUSION: The study suggested that the antioxidation of aspirin was brought into action by affecting the cellular iron metabolism pathway to induce ferritin synthesis.

Antioxidants↗

PubMed2001

[The relationship between acoustic analysis and auditory assessment].

OBJECTIVE: To investigate the relationship between acoustic analysis and auditory assessment of hoarseness. METHOD: 24 normal and 154 cases of pathological voice were included in this research. They were divided into 4 groups with different hoarseness and were accepted acoustic analysis. The parameters were analyzed by SPSS statistical software. RESULT: There were significant difference on acoustical parameters among each group excluding no difference of the jitter between normal and light hoarseness. NNE and SNR were the major parameters in descriptive of hoarseness. There were good correlation between 5 parameters and hoarseness assessment. CONCLUSION: Acoustic analysis is a useful method in clinical application to assess hoarseness with objective and simple advantage.

Adolescent↗

PubMed2001

[Evaluation of cerebral circulatory compensation after carotid artery occlusion in rabbits].

OBJECTIVE: To observe the cerebral circular changes of rabbits during brain ischemia caused by carotid artery occlusion (CAO) with a loading test-cerebral vascular CO2 reactivity (CVR) technique. METHODS: Sixty white rabbits were divided into 6 groups, before and during 0-50 days after CAO, we studied the regional cerebral blood flow (rCBF) and CVR of frontal lobe on the same side, using laser doppler perfusion imager (LDI). RESULT: The rCBF-lesion caused by CAO could hardly be observed (P > 0.5), but CVR cut down obviously (P < 0.01). CONCLUSIONS: The loading test-cerebral vascular CO2 reactivity (CVR) allow the hemodynamic effect of a CAO on the intracerebral circulation to be observed before the reduced rCBF can be detected.

Animals↗

PubMed2000

Structure and mechanism of homoserine kinase: prototype for the GHMP kinase superfamily.

BACKGROUND: Homoserine kinase (HSK) catalyzes an important step in the threonine biosynthesis pathway. It belongs to a large yet unique class of small metabolite kinases, the GHMP kinase superfamily. Members in the GHMP superfamily participate in several essential metabolic pathways, such as amino acid biosynthesis, galactose metabolism, and the mevalonate pathway. RESULTS: The crystal structure of HSK and its complex with ADP reveal a novel nucleotide binding fold. The N-terminal domain contains an unusual left-handed betaalphabeta unit, while the C-terminal domain has a central alpha-beta plait fold with an insertion of four helices. The phosphate binding loop in HSK is distinct from the classical P loops found in many ATP/GTP binding proteins. The bound ADP molecule adopts a rare syn conformation and is in the opposite orientation from those bound to the P loop-containing proteins. Inspection of the substrate binding cavity indicates several amino acid residues that are likely to be involved in substrate binding and catalysis. CONCLUSIONS: The crystal structure of HSK is the first representative in the GHMP superfamily to have determined structure. It provides insight into the structure and nucleotide binding mechanism of not only the HSK family but also a variety of enzymes in the GHMP superfamily. Such enzymes include galactokinases, mevalonate kinases, phosphomevalonate kinases, mevalonate pyrophosphate decarboxylases, and several proteins of yet unknown functions.

Adenosine Diphosphate↗

PubMed2000

A kinetic model for the action of a resistance efflux pump.

ArsA is the catalytic subunit of the arsenical pump, coupling ATP hydrolysis to the efflux of arsenicals through the ArsB membrane protein. It is a paradigm for understanding the structure-function of the nucleotide binding domains (NBD) of medically important efflux pumps, such as P-glycoprotein, because it has two sequence-related, interacting NBD, for which the structure is known. On the basis of a rigorous analysis of the pre-steady-state kinetics of nucleotide binding and hydrolysis, we propose a model in which ArsA alternates between two mutually exclusive conformations as follows: the ArsA(1) conformation in which the A1 site is closed but the A2 site open; and the ArsA(2) conformation, in which the A1 and A2 sites are open and closed, respectively. Antimonite elicits its effects by sequestering ArsA in the ArsA(1) conformation, which catalyzes rapid ATP hydrolysis at the A2 site to drive ArsA between conformations that have high (nucleotide-bound ArsA) and low affinity (nucleotide-free ArsA) for Sb(III). ArsA potentially utilizes this process to sequester Sb(III) from the medium and eject it into the channel of ArsB.

Adenosine Diphosphate↗

PubMed2000

Adeno-associated virus production of soluble tumor necrosis factor receptor neutralizes tumor necrosis factor alpha and reduces arthritis.

The major limitation of adenovirus is its association with induction of an inflammatory response and relatively short-term production of the gene therapy transgene product. Adeno-associated virus (AAV) is a 4.68-kb single-strand DNA virus that contains ITRs for viral replication and a packaging signal, and also has been engineered to contain therapeutic genes up to 5 kb in length. Transduction of recombinant AAV (rAAV) results in low inflammatory response and long-term expression. We have cloned a low-immunogenic form of human sTNFRI (sTNFRI2.6D) into AAV (rAAVsTNFRI). This vector was analyzed for its ability to transfect and neutralize the effect of TNF-alpha on primary rheumatoid arthritis synovial fibroblast (RASFs). The rAAVsTNFRI was transduced into the cells at 1.8 x 10(1), 1.8 x 10(2), and 1.8 x 10(3) viral particles per cell. There was greater than 90% neutralization of TNF-alpha at 1.8 x 10(3) viral particles/cell. There was a significant decrease in the synovial cell hyperplasia and cartilage and bone destruction in human TNF-alpha transgenic mice treated intraarticularly with rAAVsTNFRI. These results indicate that the low-immunogenic and long-term expressing vector, rAAVsTNFRI, can be used to deliver the soluble TNF-alpha in vitro and in vivo and effectively reduce the severity of arthritis.

Animals↗

PubMed2000

Structure of the ArsA ATPase: the catalytic subunit of a heavy metal resistance pump.

Active extrusion is a common mechanism underlying detoxification of heavy metals, drugs and antibiotics in bacteria, protozoa and mammals. In Escherichia coli, the ArsAB pump provides resistance to arsenite and antimonite. This pump consists of a soluble ATPase (ArsA) and a membrane channel (ArsB). ArsA contains two nucleotide-binding sites (NBSs) and a binding site for arsenic or antimony. Binding of metalloids stimulates ATPase activity. The crystal structure of ArsA reveals that both NBSs and the metal-binding site are located at the interface between two homologous domains. A short stretch of residues connecting the metal-binding site to the NBSs provides a signal transduction pathway that conveys information on metal occupancy to the ATP hydrolysis sites. Based on these structural features, we propose that the metal-binding site is involved directly in the process of vectorial translocation of arsenite or antimonite across the membrane. The relative positions of the NBS and the inferred mechanism of allosteric activation of ArsA provide a useful model for the interaction of the catalytic domains in other transport ATPases.

Adenosine Triphosphatases↗

PubMed2000

Differential regulation and function of Fas expression on glial cells.

Fas/Apo-1 is a member of the TNF receptor superfamily that signals apoptotic cell death in susceptible target cells. Fas or Fas ligand (FasL)-deficient mice are relatively resistant to the induction of experimental allergic encephalomyelitis, implying the involvement of Fas/FasL in this disease process. We have examined the regulation and function of Fas expression in glial cells (astrocytes and microglia). Fas is constitutively expressed by primary murine microglia at a low level and significantly up-regulated by TNF-alpha or IFN-gamma stimulation. Primary astrocytes express high constitutive levels of Fas, which are not further affected by cytokine treatment. In microglia, Fas expression is regulated at the level of mRNA expression; TNF-alpha and IFN-gamma induced Fas mRNA by approximately 20-fold. STAT-1alpha and NF-kappaB activation are involved in IFN-gamma- or TNF-alpha-mediated Fas up-regulation in microglia, respectively. The cytokine TGF-beta inhibits basal expression of Fas as well as cytokine-mediated Fas expression by microglia. Upon incubation of microglial cells with FasL-expressing cells, approximately 20% of cells underwent Fas-mediated cell death, which increased to approximately 60% when cells were pretreated with either TNF-alpha or IFN-gamma. TGF-beta treatment inhibited Fas-mediated cell death of TNF-alpha- or IFN-gamma-stimulated microglial cells. In contrast, astrocytes are resistant to Fas-mediated cell death, however, ligation of Fas induces expression of the chemokines macrophage inflammatory protein-1beta (MIP-1beta), MIP-1alpha, and MIP-2. These data demonstrate that Fas transmits different signals in the two glial cell populations: a cytotoxic signal in microglia and an inflammatory signal in the astrocyte.

Animals↗

PubMed2000

Gene therapy that inhibits nuclear translocation of nuclear factor kappaB results in tumor necrosis factor alpha-induced apoptosis of human synovial fibroblasts.

OBJECTIVE: Tumor necrosis factor alpha (TNFalpha) increases the survival and proliferation of human rheumatoid arthritis (RA) cell lines. These experiments were designed to determine if inhibition of nuclear factor kappaB (NF-kappaB) nuclear translocation leads to increased apoptosis of TNFalpha-treated human RA cell lines. METHODS: We constructed an inhibitor of nuclear factor kappaB(IkappaB) dominant-negative adenovirus (AdCMVIkappaB-DN) and an X-linked inhibitor of apoptosis (XIAP) antisense adenovirus (AdCMVXIAP-AS). Primary RA synovial fibroblast (RASF) cell lines were transfected in vitro, and SV40-transformed RA synovial cell lines in SCID mice were transfected in vivo. Cells were treated with TNFalpha and analyzed for apoptosis. RESULTS: There was no apoptosis of primary RASF transfected in vitro with AdCMVIkappaB-DN alone. In contrast, there was apoptosis of >85% of cells treated with AdCMVIkappaB-DN plus TNFalpha. Primary RASF in SCID mice also exhibited high levels of apoptosis after in vivo transfection with AdCMVIkappaB-DN followed by treatment with TNFalpha. There was no apoptosis after treatment with AdCMVIkappaB-DN in the absence of TNFalpha. XIAP is an inhibitor of apoptosis which was up-regulated by TNFalpha, and this up-regulation was inhibited by AdCMVIkappaB-DN plus TNFalpha. Transfection of an AdCMVXIAP-AS gene therapy resulted in increased TNFa-induced apoptosis. CONCLUSION: AdCMVIkappaB-DN gene therapy greatly enhances apoptosis due to inhibition of an NF-kappaB-mediated antiapoptosis signaling pathway, and XIAP is a TNFalpha-inducible specific inhibitor of apoptosis in RA synovial cell lines. This and other modulators of TNF receptor or the Fas apoptosis pathway may be therapeutically beneficial in facilitating apoptosis of synovial tissue in patients with RA.

Animals↗

PubMed2000

Determination of idarubicin in human urine by capillary zone electrophoresis with amperometric detection.

A simple, reliable and reproducible method, based on capillary zone electrophoresis with amperometric detection, has been developed for the determination of idarubicin in human urine. A carbon disk electrode was used as working electrode. The optimal conditions of separation and detection were pH 5.6 phosphate buffer (0.20 mol/L), 22 kV for the separation voltage and 1.00 V (vs. Ag/AgCl, 3 mol/L KCl) for the detection potential. The linear range was from 4.0 x 10(-7) to 2.0 x 10(-5) mol/L with a regression coefficient of 0.9986, and the detection limit was 8.0 x 10(-8) mol/L. The method was directly applied to the determination of idarubicin in spiked human urine without any other sample pretreatment except filtration, and the assay results were satisfactory.

Antibiotics, Antineoplastic↗

PubMed2000

Micellar electrokinetic capillary electrophoresis for rapid analysis of patulin in apple cider.

A micellar electrokinetic capillary chromatography (MECC) mode was applied to a capillary electrophoresis (CE) method, which was developed for detection and quantitation of patulin in apple ciders. This method used a small sample amount (2 mL) and consumed minimal organic solvent compared to the most commonly used HPLC methods. The sample preparation procedure of the CE method was also simpler than other chromatographic techniques developed for patulin analysis. Patulin was detected with a photodiode array detector at 273 nm. The standard curve was linear (r(2) = 0.9984) from 75 microgram/L to 121 microgram/mL with patulin working solutions corresponding to 3.8 microgram/L to 6.1 microgram/mL patulin in the sample. The linearity was better in a narrower range of concentrations (r(2) = 0.9999) from 75 microgram/L to 24.1 microgram/mL. The limit of detection of the method was 3.8 microgram/L. Patulin recoveries at 4 levels in spiked samples (10-121 microgram/L) ranged from 95.2 to 105.4%. The recoveries were 96. 9% and 99.2% for 2 levels (22.3 and 223 microgram/L, respectively) of patulin in infected apple samples. This method represents a unique alternative method for rapid and sensitive analysis of patulin in apple ciders.

Beverages↗

PubMed2000

Dynamics and changing environments in highly optimized tolerance

Highly optimized tolerance (HOT) is a mechanism for power laws in complex systems based on the robust design of systems in uncertain environments. Once the system, the environment, and the optimization scheme have been specified, the HOT state is fixed and corresponds to the set of measure zero (typically a single point) in the configuration space which minimizes a cost function U. Here we explore the U-dependent structures in configuration space which are associated with departures from the optimal state. We introduce dynamics, quantified by an effective temperature T, such that T=0 corresponds to the original HOT state, while T-->infinity corresponds to completely random configurations. More generally, T defines the range in state space over which fluctuations are likely to be observed. In a fixed environment fluctuations always raise the average cost. However, in a time-dependent environment, mobile configurations can lower the average U because they adjust more efficiently to changes.

Journal Article↗

PubMed2000

Combination therapy with lamivudine and adenovirus causes transient suppression of chronic woodchuck hepatitis virus infections.

Treatment of hepatitis B virus carriers with the nucleoside analog lamivudine suppresses virus replication. However, rather than completely eliminating the virus, long-term treatment often ends in the outgrowth of drug-resistant variants. Using woodchucks chronically infected with woodchuck hepatitis virus (WHV), we investigated the consequences of combining lamivudine treatment with immunotherapy mediated by an adenovirus superinfection. Eight infected woodchucks were treated with lamivudine and four were infected with approximately 10(13) particles of an adenovirus type 5 vector expressing beta-galactosidase. Serum samples and liver biopsies collected following the combination therapy revealed a 10- to 20-fold reduction in DNA replication intermediates in three of four woodchucks at 2 weeks after adenovirus infection. At the same time, covalently closed circular DNA (cccDNA) and viral mRNA levels both declined about two- to threefold in those woodchucks, while mRNA levels for gamma interferon and tumor necrosis factor alpha as well as for the T-cell markers CD4 and CD8 were elevated about twofold. Recovery from adenovirus infection was marked by elevation of sorbitol dehydrogenase, a marker for hepatocyte necrosis, as well as an 8- to 10-fold increase in expression of proliferating cell nuclear antigen, a marker for DNA synthesis, indicating significant hepatocyte turnover. The fact that replicative DNA levels declined more than cccDNA and mRNA levels following adenovirus infection suggests that the former decline either was cytokine induced or reflects instability of replicative DNA in regenerating hepatocytes. Virus titers in all four woodchucks were only transiently suppressed, suggesting that the effect of combination therapy is transient and, at least under the conditions used, does not cure chronic WHV infections.

Adenoviridae↗

PubMed2000

Alleviation of human papillomavirus E2-mediated transcriptional repression via formation of a TATA binding protein (or TFIID)-TFIIB-RNA polymerase II-TFIIF preinitiation complex.

Transcription in human papillomaviruses (HPVs) is mainly regulated by cellular transcription factors and virus-encoded E2 proteins that act as sequence-specific DNA-binding proteins. Although the functions of E2 as a transcriptional activator and a repressor have been well documented, the role of cellular factors involved in E2-mediated regulation of the HPV promoters and the mechanism by which E2 modulates viral gene expression remain unclear. Using reconstituted cell-free transcription systems, we found that cellular enhancer-binding factors and general cofactors, such as TAF(II)s, TFIIA, Mediator, and PC4, are not required for E2-mediated repression. Unlike other transcriptional repressors that function through recruitment of histone deacetylase or corepressor complexes, HPV E2 is able to directly target components of the general transcription machinery to exert its repressor activity on the natural HPV E6 promoter. Interestingly, preincubation of TATA binding protein (TBP) or TFIID with HPV template is not sufficient to overcome E2-mediated repression, which can be alleviated only via formation of a minimal TBP (or TFIID)-TFIIB-RNA polymerase II-TFIIF preinitiation complex. Our data therefore indicate that E2 does not simply work by displacing TBP or TFIID from binding to the adjacent TATA box. Instead, E2 appears to function as an active repressor that directly inhibits HPV transcription at steps after TATA recognition by TBP or TFIID.

Base Sequence↗