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Biomedical subjects

Y Tang

Publications and source records attributed to Y Tang.

At least 91 records · Page 5Linked to original sources
PubMed2001

[Homologous recombination in Streptomyces lincolnensis B48].

To study frequency and mechanism of homologous recombination in Streptomyces, an E. coli plasmid which cannot replicate in Streptomyces was transformed into Streptomyces lincolnensis B48. After homologous recombination between delta lincomycin biosynthetic genes inactivated by thiostrepton resistant gene (tsr) carried on pYYE04al and homologous sequences on the chromosome, S. lincolnensis YY1 and S. lincolnensis, YY2 were obtained on SMA with low thiostrepton concentration. Hybridization of chromosomal DNA samples of S. lincolnensis YY1, S. lincolnensis YY2, standard S. lincolnensis and S. lincolnensis YYc digested with SmaI with the probe of tsr gene gave signal corresponding to a fragment of 1.5 kb in the former two; Nevertheless, hybridization of chromosomal DNA digested with Hind III and Sma I using the probe of delta lacZ' gene resulted in positive fragment of 4.4 kb only in S. lincolnensis YY2. Southern hybridizations indicate that S. lincolnensis YY1 is the result of homologous exchange while S. lincolnensis YY2 comes from bomologous recombination. To prove the existence of E. coli replicon and ampicillin resistant gene on the chromosome of S. lincolnensis YY2, its DNA digested with SphI was ligated and then transformed into E. coli JM83 competent cell. Two transformants named pSLE1 grew on the plate containing ampicillin. It's confirmed that pSLE1 is a part of pYYE04a1 from its digestion with different enzymes.

Chromosomes, Bacterial↗
PubMed2001

[Effects of quanjia yangshen capsule on rate of polychromatic erythrocytic micronucleus formation and peripheral blood picture in mice treated by cyclophosphamide].

OBJECTIVE: To observe the effect of Quanjia Yangshen capsule (QJYS) on cyclophosphamide (Cy) induced teratogenesis and bone marrow in mice and to explore the mechanism of its clinical therapeutic effect. METHODS: Mice were separately administered with QJYS solely, Cy solely and QJYS + Cy and the effect on polychromatic erythrocytic (PE) micronucleus formation rate in the bone marrow of mice, and peripheral blood picture were observed and compared with the control group. RESULTS: High dosage of QJYS has no apparent effect on PE micronucleus formation rate and peripheral blood picture in the normal mice; Cy can obviously raise PE micronucleus formation rate (P < 0.01), and lowered WBC, RBC and Hb obviously (P < 0.01) in mice. After taking QJYS, the Cy induced micronucleus formation rate increasing and blood picture parameters lowering were controlled. The improvement in the high and middle dose QJYS group was significantly higher in comparing to that in the sole Cy group (P < 0.01); while the low dose QJYS group in comparing with Cy group also showed significant improvement (P < 0.01), except Hb value. CONCLUSION: QJYS could significantly antagonize teratogenic effect and inhibition to bone marrow of Cy, i.e., play an antagonistic role against the toxic and side-effects of Cy.

Animals↗
PubMed2001

[Study on hypermethylation of the calcitonin gene in malignant hematological disorders].

OBJECTIVE: To investigate the clinical significance of hypermethylation of the calcitonin (CT) gene in malignant hematological disorders (MHD). METHODS: Polymerase chain reaction (PCR) in combination with digestion of DNA with Hpa II was used to examine the methylation patterns of the CT gene in 73 patients with MHD, 6 healthy people and 24 patients with nonmalignant hematological disorders (NON-MHD). RESULTS: Hypermethylation of the CT gene occurred in 12 of 14 (85.7%) patients with acute lymphoblastic leukemia (ALL), 9 of 15 (60%) acute nonlymphocytic leukemia (ANLL), 8 of 10 (80%) chronic myelogenous leukemia (CML), 5 of 15 (33.3%) malignant lymphoma (ML), 2 of 5 patients with myelodysplastic syndrome (MDS), 1 of 2 malignant histiocytosis (MH), 1 of 3 chronic lymphocytic leukemia (CLL) and 1 of 9 multiple myeloma (MM). However, it did not occur in normal controls and NON-MHD. CONCLUSION: Hypermethylation of CT gene may serve as an important molecular maker for tumorous cell clone and may be useful in diagnosing MHD, monitoring minimal residual disease and predicting prognosis.

Calcitonin↗
PubMed2001

Endogenous expression and HLA stabilization assay of Plasmodium falciparum CTL epitope minigene in human HLA-A2. 1 and HLA-B51 cells.

OBJECTIVE: To evaluate the Plasmodium falciparum CTL epitope vaccines in HLA class I allele specific human cell lines that have high frequency among Chinese population. METHODS: Synthesized oligonucleotides encoding for P. f. CTL epitope genes, constructed eukaryotic expression plasmids, transfected the minigenes into HLA class I allele specific human cell lines and identified endogenous expressing of the minigenes by RT-PCR and HLA stabilization assay. RESULTS: Two mini-genes encoding Plasmodium falciparum CTL epitopes were designed and cloned, respectively, into an eukaryotic expressing vector to form TR26 which was restricted to HLA-B51, SH6 which was restricted to HLA-A2. 1, and TS, which had the two aforementioned mini-genes fused in tandem. All of these CTL epitope genes were transfected and endogenously expressed in respective cell lines containing appropriate HLA molecules. The obviously increased expressions of HLA class I molecules were detected in the transfected cell lines. It was demonstrated that the two discrete Plasmodium falciparum epitope genes were effectively processed and presented, and the close proximity of the two epitope genes in one chain as in mini-gene TS did not interfere with the processing and presenting of each epitope gene in corresponding cell line. CONCLUSION: A successful expression and presentation of multiple CTL epitope mini-gene in MHC class I allele specific human cell lines were demonstrated by an in vitro assay, which could be corresponding to the vaccination of CTL vaccines in people with different MHC I molecules. This work also suggested the possibility of constructing a multiple CTL epitope Plasmodium falciparum DNA vaccine that could cover most of Chinese population.

Animals↗
PubMed2000

Functionally inert HIV-specific cytotoxic T lymphocytes do not play a major role in chronically infected adults and children.

The highly sensitive quantitation of virus-specific CD8(+) T cells using major histocompatibility complex-peptide tetramer assays has revealed higher levels of cytotoxic T lymphocytes (CTLs) in acute and chronic virus infections than were recognized previously. However, studies in lymphocytic choriomeningitis virus infection have shown that tetramer assays may include measurement of a substantial number of tetramer-binding cells that are functionally inert. Such phenotypically silent CTLs, which lack cytolytic function and do not produce interferon (IFN)-gamma, have been hypothesized to explain the persistence of virus in the face of a quantitatively large immune response, particularly when CD4 help is impaired. In this study, we examined the role of functionally inert CTLs in chronic HIV infection. Subjects studied included children and adults (n = 42) whose viral loads ranged from <50 to >100,000 RNA copies/ml plasma. Tetramer assays were compared with three functional assays: enzyme-linked immunospot (Elispot), intracellular cytokine staining, and precursor frequency (limiting dilution assay [LDA]) cytotoxicity assays. Strong positive associations were observed between cell numbers derived by the Elispot and the tetramer assay (r = 0.90). An even stronger association between tetramer-derived numbers and intracellular cytokine staining for IFN-gamma was present (r = 0.97). The majority (median 76%) of tetramer-binding cells were consistently detectable via intracellular IFN-gamma cytokine staining. Furthermore, modifications to the LDA, using a low input cell number into each well, enabled LDAs to reach equivalence with the other methods of CTL enumeration. These data together show that functionally inert CTLs do not play a significant role in chronic pediatric or adult HIV infection.

Adult↗
PubMed2000

beta 1-adrenergic receptor association with PSD-95. Inhibition of receptor internalization and facilitation of beta 1-adrenergic receptor interaction with N-methyl-D-aspartate receptors.

The beta(1)-adrenergic receptor (beta(1)AR) is the most abundant subtype of beta-adrenergic receptor in the mammalian brain and is known to potently regulate synaptic plasticity. To search for potential neuronal beta(1)AR-interacting proteins, we screened a rat brain cDNA library using the beta(1)AR carboxyl terminus (beta(1)AR-CT) as bait in the yeast two-hybrid system. These screens identified PSD-95, a multiple PDZ domain-containing scaffolding protein, as a specific binding partner of the beta(1)AR-CT. This interaction was confirmed by in vitro fusion protein pull-down and blot overlay experiments, which demonstrated that the beta(1)AR-CT binds specifically to the third PDZ domain of PSD-95. Furthermore, the full-length beta(1)AR associates with PSD-95 in cells, as determined by co-immunoprecipitation experiments and immunofluorescence co-localization studies. The interaction between beta(1)AR and PSD-95 is mediated by the last few amino acids of the beta(1)AR, and mutation of the beta(1)AR carboxyl terminus eliminated the binding and disrupted the co-localization of the beta(1)AR and PSD-95 in cells. Agonist-induced internalization of the beta(1)AR in HEK-293 cells was markedly attenuated by PSD-95 co-expression, whereas co-expression of PSD-95 has no significant effect on either desensitization of the beta(1)AR or beta(1)AR-induced cAMP accumulation. Furthermore, PSD-95 facilitated the formation of a complex between the beta(1)AR and N-methyl-d-aspartate receptors, as assessed by co-immunoprecipitation. These data reveal that PSD-95 is a specific beta(1)AR binding partner that modulates beta(1)AR function and facilitates physical association of the beta(1)AR with synaptic proteins, such as the N-methyl-d-aspartate receptors, which are known to be regulated by beta(1)AR stimulation.

Animals↗
PubMed2000

Association of mammalian trp4 and phospholipase C isozymes with a PDZ domain-containing protein, NHERF.

Mammalian homologues of Drosophila Trp have been implicated to form channels that are activated following the depletion of Ca(2+) from internal stores. Recent studies indicate that actin redistribution is required for the activation of these channels. Here we show that murine Trp4 and Trp5, as well as phospholipase C beta1 and beta2 interact with the first PDZ domain of NHERF, regulatory factor of the Na(+)/H(+) exchanger. We demonstrated the association of Trp4 and phospholipase C-beta1 with NHERF in vivo in an HEK293 cell line expressing Trp4 and in adult mouse brain by immuno-coprecipitation. NHERF is a two PDZ domain-containing protein that associates with the actin cytoskeleton via interactions with members of ezrin/radixin/moesin family. Thus, store-operated channels involving Trp4 and Trp5 can form signaling complexes with phospholipase C isozymes via interactions with NHERF and thereby linking the lipase and the channels to the actin cytoskeleton. The interaction with the PDZ protein may constitute an important mechanism for distribution and regulation of store-operated channels.

Amino Acid Sequence↗
PubMed2000

Kinase-inducible domain-like region of HTLV type 1 tax is important for NF-kappaB activation.

Partial proteolysis of HTLV-1 Tax protein has revealed the region surrounding amino acid residues (88)KVL(90) to be highly exposed. The protein sequence surrounding this region ((81)QRTSKTLKVLTPPIT(95)) bears resemblance to the kinase-inducible domain (KID, (129)SRRPSYRKILNE(140)) of CREB and is involved in recruiting transcriptional coactivators, p300 and CBP, for trans-activating the viral long terminal repeat (LTR). Data have also revealed the KID-like region to be important for Tax binding to DNA. Here we report that single (K88A, V89A, L90A) and double alanine substitutions (V89A-L90A) in the (88)KVL(90) motif attenuate the ability of Tax to activate NF-kappaB. Deletions near or spanning this motif also had the same effect. The alanine substitutions affect HTLV-1 LTR activation and NF-kappaB activation differently, with K88A and V89A mutants showing much reduced activities for HTLV LTR activation while retaining attenuated but significant NF-kappaB-activating function. In contrast, although the L90A mutant is similarly attenuated for NF-kappaB activation, it showed significant activity in LTR trans-activation. Incorporation of both V89A and L90A substitutions in a V89A-L90A double mutant further reduced NF-kappaB activation and completely abrogated LTR trans-activation. In aggregate, these results demonstrate the importance of the KID-like domain of Tax and implicate its interaction with cellular factors other than p300/CBP in NF-kappaB activation.

Amino Acid Motifs↗
PubMed2000

[Determination of vanillymandelic acid in urine by high performance liquid chromatography].

OBJECTIVE: To develop a high performance liquid chromatography(HPLC) for determining vanillylmandelic acid(VMA) in urine. METHODS: The analytical column was packed with Nova-Pak C18. Flow rate was 0.9 ml.min-1. The mobile phase was 40 mmol.L-1 NaH2PO4 buffer. The VMA of 30 healthy people in 24 hour urine were tested by the internal standard method and with electrochemical detector. RESULT: The linear range was from 5 mumol.L-1 to 200 mumol.L-1. The mean analytical recovery rate was 99.1%. The mean within-day coefficient of variation(CV) was 5.8%, and the mean day-to-day CV was 7.7%. The detection limit was 0.28 mumol.L-1. The VMA of 24 hour urine was 18.13 +/- 6.17 mumol in healthy people. CONCLUSIONS: The method is suitable for routine determination of VMA in urine.

Adolescent↗
PubMed2000

Spatiotemporal expression of BDNF in the hippocampus induced by the continuous intracerebroventricular infusion of beta-amyloid in rats.

The beta-amyloid protein (Abeta) is the major component of senile plaques found in the brain in Alzheimer's disease (AD). Its neurotoxic properties in vivo, however, are not well defined. Since the expression of neurotrophin genes is considered an important component of the intrinsic neuroprotective response to insults, we analyzed the gene expression of neurotrophins in the brains of rats which received a continuous infusion of Abeta-(1-42) into the cerebroventricle. Northern blot analysis revealed a significant increase in brain-derived neurotrophic factor (BDNF) expression in the hippocampus but no change in the cerebral cortices. The alteration peaked on days 3-7 and returned to the basal level on day 14 after the start of Abeta-(1-42) infusion. No significant changes in nerve growth factor or neurotrophin-3 mRNA expression were observed. The infusion of Abeta-(1-40) and (25-35) also triggered the expression of BDNF mRNA, whereas neither Abeta-(40-1) nor (1-16) had any effect. In situ hybridization histochemistry revealed that the expression mainly occurred in the hilus and granular layer of the dentate gyrus and to a lesser extent in the pyramidal neurons of the CA1 region. These results demonstrate that the continuous intracerebroventricular infusion of Abeta induces selective and spatiotemporal expression of BDNF mRNA in the hippocampus.

Alzheimer Disease↗
PubMed2000

[Discriminant function based on serum analyte for diagnosis of primary hepatic cancer].

OBJECTIVE: The aim of this study was to diagnose primary hepatic cancer(PHC). METHODS: Seven serum indexes of 92 serum samples consisting of 48 controls and 44 PHC were detected. Four discriminant functions based on seven serum indexes were obtained with computer SPSS statistic package. RESULTS: The rate of coincidence, sensitivity, and specificity of the general discriminant functions were 86.96%, 77.27%, and 95.83% respectively; and that of the stepwise discriminant functions were 84.78%, 79.55%, and 89.59% respectively. CONCLUSION: Usually PHC can be diagnosed by analyzing patients serum indexes with the discriminant functions.

Adult↗
PubMed2000

[Ischemic preconditioning decrease the release of cardiac troponin T during heart valve replacement].

Using cardiac troponin T(cTnT), a highly sensitive and specific marker of myocardial injury, we evaluated the effects of ischemic precondition on ischemic reperfusion myocardial injury. Thirty two patients were randomly divided into control group(n = 16) and ischemic preconditioning group(n = 16). The marker cTnT was measured in each group before operation, and 4 h, 24 h and 72 h after operation. The results showed that the peak value of cTnT was lower, and more quickly recovered in the preconditioning group than that in the control. It is suggested that ischemic preconditioning exert an evidently protective effect on ischemic reperfusion myocardial injury.

Adult↗
PubMed2000

Anti-Gal antibodies in humans and 1, 3alpha-galactosyltransferase knock-out mice.

BACKGROUND: Due to the absence of alphaGAL epitopes, humans and galactosyltransferase knock-out (GALT/ KO) mice express high levels of anti-Gal antibodies. We describe the properties of mouse anti-GAL antibodies. METHODS: Anti-GAL IgG antibodies were quantified by affinity purification. Antibody affinities and avidities were determined in direct binding and competition assays. Antibody-mediated rejection was investigated using hyperimmunized GALT/KO mice as recipients of GAL+ heart allografts. RESULTS: In young GALT/KO mice the levels of anti-GAL antibodies were low. Immunization of GALT/KO mice resulted in increased anti-GAL antibody expression. In mouse serum 0.6% of IgG was specific for alphaGAL compared to 0.5% in human serum. The avidity of purified mouse and human anti-GAL IgG was 30 and 6 nM, the affinity 15 and 50 microM, respectively. The isotype distribution in mouse and human anti-GAL IgG appeared to be similar to the isotype distribution in normal sera. The affinity of mouse and human anti-GAL IgM was 150 and 750 microM, respectively. Immunized GALT/KO recipients of GAL+ heart transplants rejected their grafts within 2 hr although nonimmunized GALT/KO mice retained their grafts for up to 6 days. Immunohistological examination of the rejected GAL+ hearts revealed massive deposition of IgM and IgG on endothelial cells of the graft with a concomitant deposition of complement. CONCLUSIONS: Our studies demonstrate that anti-GAL antibodies from immunized GALT/KO mice bind alphaGAL with an avidity/affinity similar to human anti-GAL antibodies and are able to induce hyperacute rejection of GAL+ heart allografts.

Animals↗
PubMed2000

p300 and p300/cAMP-responsive element-binding protein associated factor interact with human T-cell lymphotropic virus type-1 Tax in a multi-histone acetyltransferase/activator-enhancer complex.

The human T-cell lymphotropic virus, type (HTLV)-1 trans-activator, Tax, coordinates with cAMP-responsive element-binding protein (CREB) and the transcriptional co-activators p300/CBP on three 21-base pair repeat elements in the proviral long terminal repeat (LTR) to promote viral mRNA transcription. Recruitment of p300/CBP to the activator-enhancer complex, however, is insufficient to support Tax-dependent LTR trans-activation. Here, we report that the p300/CBP-associated factor (P/CAF) is a critical and integral component of the functional HTLV-1 activator-enhancer complex. The HTLV-1 Tax protein directly binds P/CAF in vitro and co-immunoprecipitates with this co-activator in vivo. The Tax mutants (K88A and V89A) defective for p300/CBP-binding and LTR trans-activation, retained their abilities to interact with P/CAF. The M47 mutant (L319R, L320S) protein, which has previously been shown to interact with p300/CBP, by contrast, failed to form complexes with P/CAF and is impaired in LTR trans-activation. Furthermore, LTR trans-activation by Tax is competitively inhibited by the adenoviral E1A 12S gene product, which displaces P/CAF from p300/CBP and inhibits the histone acetyltransferase activities of both P/CAF and p300/CBP. This inhibition is partially reversed by exogenously added P/CAF. These results imply that simultaneous recruitment of two distinct co-activators (p300/CBP and P/CAF) by Tax is essential for the assembly of a trans-activation competent, nucleoprotein complex.

Acetyltransferases↗
PubMed2000

The Akt proto-oncogene links Ras to Pak and cell survival signals.

The Ras oncogene regulates cellular proliferation, differentiation, transformation, and survival through multiple downstream signals. Ras signals through its effector phosphoinositide 3 (PI3) kinase to the Pak protein kinase (p65(pak)), but the steps from Ras to Pak remain to be elucidated. PI3 kinase can stimulate the small G protein, Rac, a direct activator of Pak, as well as the Akt proto-oncogene, a serine-threonine protein kinase. We found that activated Akt stimulated Pak, whereas a dominant negative Akt inhibited Ras activation of Pak in transfection assays. Akt stimulation of Pak was not inhibited by dominant negative mutants of either Rac or Cdc42 suggesting that Akt activated Pak through a GTPase-independent mechanism. We also developed a novel cell-free system to study Ras activation of Pak. In this system Ras activated Pak only in the presence of a crude cell extract but failed to activate Pak when Akt was immunodepleted from the extract. Akt protects cells from apoptosis through phosphorylation of downstream targets such as the Bcl-2 family member, Bad. We found that activated Pak decreased apoptosis and increased phosphorylation of Bad, whereas dominant negative Pak increased apoptosis and decreased phosphorylation of Bad. These studies define a new oncogene-mediated cell survival signal.

Animals↗
PubMed2000

Unbiased stereological quantification of neurons in the human vestibular ganglion.

Vestibular ganglion (VG) neurons are bipolar neurons that relay peripheral vestibular information to the CNS. Neuron counts in normal humans provide a basis for quantitative studies on the effects of aging or pathological conditions in the audiovestibular systems. No prior study has employed unbiased stereological technique to count human VG neurons. This study used unbiased stereology in the form of the optical fractionator to estimate the total number of human VG neurons in archival temporal bone specimens. An average (+/- s.d.) of 27330+/-2593 neurons was found in specimens from five patients with no history of vestibular pathology. This result, a significant departure from results of past studies, provides the first unbiased baseline value to compare with future stereologically based studies on the human VG.

Adolescent↗