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Q Zhang

Publications and source records attributed to Q Zhang.

At least 415 records · Page 23Linked to original sources
PubMed1999

Identification of two hERR2-related novel nuclear receptors utilizing bioinformatics and inverse PCR.

Identification of novel nuclear receptors based on the highly conserved DNA-binding domain (DBD) has previously depended mainly on low stringency hybridization of cDNA libraries and degenerate PCR. Establishment of the expressed sequence tag (EST) database in recent years has provided an alternative approach for the discovery of novel members of gene families. The rate-limiting step is the conversion of ESTs to full-length cDNA. This article describes the identification of two novel nuclear receptors (hERRbeta2 and hERRgamma2) related to human estrogen-receptor-related receptor 2 (hERR2) by mining the EST database and retrieving of full-length cDNA via inverse PCR on subdivided primary cDNA library pools. The deduced protein sequences of hERRbeta2 and hERRgamma2 contain 500 and 458 amino acid (aa) residues respectively. Sequence analysis revealed that hERRbeta2 and hERRgamma2 respectively share 95% and 77% overall aa sequence identity with hERR2. However, the extra C-terminal domain in hERRbeta2 and extra N-terminal domain in hERRgamma2 are not present in the closely related hERR2 or mouse ERR2 (mERR2). Extensive sequence verification revealed that hERR2 previously reported as a human gene is actually a rat gene, whereas hERRbeta2 is the true human ortholog of hERR2 and mERR2. Tissue distribution studies showed that hERRgamma2 was expressed in a broader panel of tissues at a higher level than hERRbeta2. hERRbeta2 was mapped to cytogenetic locus 14q24.3 approximately -14q31, a region containing multiple loci involved in genetic diseases, including Alzheimer and diabetes. hERRgamma2 was mapped to 1q32. Given the high sequence homology between hERRbeta2 and mERR2, the two receptors may have similar biological function in vivo.

Amino Acid Sequence↗
PubMed1999

Smubp-2 represses the Epstein-Barr virus lytic switch promoter.

Smubp-2 is a novel transcription factor that was first identified through its interaction with the immunoglobulin Smu region (Mizuta et al., 1993) and has been cloned by virtue of its binding to two 12-O-tetradecanoylphorbol-13-acetate-responsive elements in the Epstein-Barr virus immediate-early BZLF1 promoter (Gulley et al., 1997). In this report, we examined the effect of Smubp-2 overexpression on BZLF1 prom oter activity. Overexpression of Smubp-2 in the B lymphocyte cell line BJAB caused repression of the BZLF1 gene promoter. A 14-bp region that partially overlaps with a 12-O-tetradecanoylphorbol-13-acetate-responsive element was required for maximal repression by Smubp-2, but some repression was also seen with a minimal promoter containing only the BZLF1 promoter TATA box and an initiation site. A 30-bp fragment containing the 14-bp region could transfer Smubp-2-mediated repression to heterologous promoters. Smubp-2 was found to associate with the basal transcription factor TATA binding protein (TBP) and to disrupt the formation of a stable TBP-TFIIA-DNA complex on the BZLF1 promoter TATA box and the adenovirus E1B promoter TATA box. Repression of the BZLF1 promoter by overexpressed Smubp-2 was rescued by overexpression of the basal factor TFIIA. These results suggest that complete repression of the BZLF1 promoter by Smubp-2 involves disruption of a functional TBP-TFIIA-TATA box complex and requires the -93 bp-to--79 bp region of the promoter.

Cell Line↗
PubMed1999

[Genetic polymorphisms of CYP1A1 and susceptibility of lung cancer].

OBJECTIVE: To assess the possible association between the polymorphisms of CYP1A1 and the susceptibility of lung cancer so as to provide clues for genetic markers of lung cancer. METHODS: CYP1A1 rare genotypes MspI C and VV were detected with the methods of PCR-RFLP and ASA in a case-control study including 59 cases of lung cancer, 59 hospital controls and 73 healthy controls. RESULTS: The frequencies of rare genotypes C and VV of the lung cancer cases were not significantly different from those of the controls, though the frequency of C(25.4%) of the lung cancer cases was higher than that (16.5%) of the controls. However, in the non-smoking group with genotype(C),the risk of lung cancers was 2.43-2.91 times greater than that of the controls. Heterozygote B was overpresented in healthy controls (61.6%),compared to that of lung cancer cases(37.3%), P <0.01,odds ratio 0.37 (95% confidence interval 0.17-0.80). CONCLUSION: Genotype C may be one of the susceptibly genetic markers of lung cancer in the non-smoking population. The risk of lung cancer can be decreased in persons with heterozygote.

Case-Control Studies↗
PubMed1999

Identification of promoter elements in mycobacteria: mutational analysis of a highly symmetric dual promoter directing the expression of replication genes of the Mycobacterium plasmid pAL5000.

The 120 bp origin of replication (ori) for the Mycobacterium plasmid pAL5000 has been shown to comprise the binding sites for the replication protein RepB as well as the start site of transcription for the repA and repB genes, encoding the replication proteins RepA and RepB. In this work it is demonstrated that a third gene product, Rap, is involved in replication in addition to the previously described proteins. Mycobacterium smegmatis cells transformed with replicons carrying the rap gene recover markedly faster upon electroporation than those transformed with the minimal replicon, which lacks rap. The rap gene, oppositely orientated to repA/B, was shown to be transcribed from a promoter orientated back-to-back to and overlapping the repA/B promoter. As a consequence of the extensive dyad symmetry in this region the two promoters share several elements, most of which are situated inside the high-affinity RepB-binding motif in the ori. Transcription of rap runs through the low-affinity RepB-binding site, which is part of the ori and necessary for replication. Both promoters were shown to be repressed by RepB. These divergent promoters were studied through site-specific mutagenesis in a xylE reporter gene assay. The analysis furnished evidence supporting the existence of a distal as well as a proximal element in mycobacterial promoters.

Bacterial Proteins↗
PubMed1999

Membrane supports as the stationary phase in high-performance immunoaffinity chromatography.

The membrane with a composite of cellulose grafted with acrylic polymers formed by polymerizing a glycidyl methacrylate in the presence of dispersed cellulose fiber was prepared as the stationary phase; the column (40 x 4 mm i.d.) which was compatible with the HPLC instrument was packed with pieces of the cut membrane. Protein A and human IgG were immobilized on the membrane stationary phase. The column based on the membrane support provided us good reproducibility, high efficiency, and low back pressure. High-performance immunoaffinity chromatographic analysis of human IgG in serum and polyclonal antibody to human IgG raised in goat was performed within 2.5 min. The fast-speed immunoaffinity analysis was developed by increasing the flow rate of the mobile phase and decreasing the duration time for the switch of the mobile phase; an operation for immunoaffinity analysis of human IgG could be finished within 30 s.

Cellulose↗
PubMed1999

Functional beta1-integrins release the suppression of fibronectin matrix assembly by vitronectin.

beta1-null GD25 fibroblasts adherent to vitronectin fail to bind the N-terminal 70-kDa matrix assembly domain of fibronectin or to assemble fibronectin (Sakai, T., Zhang, Q., Fässler, R., and Mosher, D. F. (1998) J. Cell Biol. 141, 527-538). We have made four observations that extend this finding. First, the presence of vitronectin on a substrate that otherwise can support fibronectin assembly has a dominant-negative effect on assembly. Second, the dominant-negative effect is lost when active beta1A is expressed. Third, beta1A containing the extracellular D130A inactivating mutation has a dominant-negative effect on fibronectin assembly. Fourth, beta1-null cells adherent to vitronectin are flat and lack filopodia, whereas beta1-null cells adherent to fibronectin or beta1A-expressing cells adherent to either vitronectin or fibronectin are contracted and exhibit numerous filopodia. These results reveal, therefore, that GD25 cells adherent to vitronectin can only assume a shape suitable for assembly of fibronectin when there is a countervailing signal from functional beta1-integrins.

Amino Acid Sequence↗
PubMed1999

Increased risk of hepatocellular carcinoma in male hepatitis B surface antigen carriers with chronic hepatitis who have detectable urinary aflatoxin metabolite M1.

We followed 145 men with chronic hepatitis B virus (HBV) hepatitis for 10 years to determine whether exposure to aflatoxin, or concomitant exposure to hepatitis C virus (HCV), or family history of hepatocellular carcinoma (HCC) increased the risk of developing HCC. We collected 8 monthly urine samples before beginning follow-up and pooled them to detect aflatoxin metabolite M1 (AFM1). AFM1 was detected in 78 (54%) of the subjects. The risk of HCC was increased 3.3-fold (with a 95% confidence interval of 1.2-8.7) in those with detectable AFM1 (above 3.6 ng/L). This relative risk was adjusted for age and for HCV status. The attributable risk from exposure to detectable AFM1 was 0.553 (0.087, 0.94). The relative risk of fatal cirrhosis for those with elevated AFM1 was 2.8 (0.6, 14.3), and the odds of having a persistently elevated alanine transaminase (ALT) were 2.5-fold greater in those with detectable AFM1 (P =.007). Concomitant infection with HCV increased the risk of HCC 5.8-fold (2. 0-17), adjusted for age and AFM1 status. A family history of HCC increased the risk of HCC 5.6-fold, adjusted for age and AFM1. Four men with detectable AFM1 and HCC all had missense mutation in codon 249 of the p53 gene in cancer tissues. This study shows that exposure to AFM1 can account for a substantial part of the risk of HCC in men with chronic HBV hepatitis and adds importantly to the evidence that HCV and family history of HCC increase the risk of HCC in men with chronic HBV hepatitis.

Adolescent↗
PubMed1999

Patterns of cytosine methylation in an elite rice hybrid and its parental lines, detected by a methylation-sensitive amplification polymorphism technique.

DNA methylation is known to play an important role in the regulation of gene expression in eukaryotes. In this study, we assessed the extent and pattern of cytosine methylation in the rice genome, using the technique of methylation-sensitive amplified polymorphism (MSAP), which is a modification of the amplified fragment length polymorphism (AFLP) method that makes use of the differential sensitivity of a pair of isoschizomers to cytosine methylation. The tissues assayed included seedlings and flag leaves of an elite rice hybrid, Shanyou 63, and the parental lines Zhenshan 97 and Minghui 63. In all, 1076 fragments, each representing a recognition site cleaved by either or both of the isoschizomers, were amplified using 16 pairs of selective primers. A total of 195 sites were found to be methylated at cytosines in one or both parents, and the two parents showed approximately the same overall degree of methylation (16.3%), as revealed by the incidence of differential digestion by the isoschizomers. Four classes of patterns were identified in a comparative assay of cytosine methylation in the parents and hybrid; increased methylation was detected in the hybrid compared to the parents at some of the recognition sites, while decreased methylation in the hybrid was detected at other sites. A small proportion of the sites was found to be differentially methylated in seedlings and flag leaves; DNA from young seedlings was methylated to a greater extent than that from flag leaves. Almost all of the methylation patterns detected by MSAP could be confirmed by Southern analysis using the isolated amplified fragments as probes. The results clearly demonstrate that the MSAP technique is highly efficient for large-scale detection of cytosine methylation in the rice genome. We believe that the technique can be adapted for use in other plant species.

Base Sequence↗
PubMed1999

Trophic effects of relaxin on reproductive tissue: role of the IGF system.

Although the growth promoting actions of relaxin on the reproductive tract have been well documented, the means by which relaxin stimulates reproductive tissue growth has not been identified. This report is an overview of studies from our laboratory investigating the role of the insulin-like growth factor (IGF) system in relaxin-induced growth of ovarian and uterine tissues. In the pig ovary, concentrations of relaxin that promote both theca and granulosa cell (GC) DNA synthesis in vitro also significantly (P < 0.05) increased GC IGF-I secretion. When IGF-I activity was blocked in the presence of an IGF-I antibody, the trophic effects of relaxin on GC [3H]thymidine incorporation into DNA were inhibited. However, there was no effect of relaxin on GC IGF binding proteins or IGF-I receptor. In the uterus, in vivo relaxin administration to prepubertal pigs resulted in the stimulation of growth and increases in uterine luminal IGF-I, IGF-II, and IGF binding proteins-2 and -3 secretion (P < 0.05). Thus, the trophic effects of relaxin on ovarian granulosa cells and the uterus involve tissue-specific changes in the IGF system. Additional studies are necessary to better understand the contribution of relaxin to follicular growth and uterine accommodation. These include characterization of the relaxin receptor and post-receptor binding events, as well as the potential impact of relaxin on other growth factor systems and how these systems interact to ultimately drive reproductive tissue growth.

Animals↗
PubMed1999

Differences in phosphorylation of the IL-2R associated JAK/STAT proteins between HTLV-I(+), IL-2-independent and IL-2-dependent cell lines and uncultured leukemic cells from patients with adult T-cell lymphoma/leukemia.

To determine activation status of the IL-2R-associated (Jak/STAT) pathway in the HTLV-I infected cells, we examined tyrosine phosphorylation of Jak3, STAT3, and STAT5 in several HTLV-I(+) T-cell lines and in uncultured leukemic T cells isolated from patients with adult T-cell lymphoma/leukemia (ATLL). Constitutive basal phosphorylation of Jak3 and, usually, STAT3 and STAT5 was detected in all four IL-2-independent cell lines tested, but in none of the three IL-2-dependent cell lines. Similarly, there was no detectable basal phosphorylation of Jak3 and STAT5 in the leukemic cells from ATLL patients (0/8 and 0/3, respectively). However, stimulation with IL-2 resulted in Jak3 and STAT5 phosphorylation in both leukemic ATLL cells and IL-2-dependent lines. Furthermore, expression of SHP-1 phosphatase which is a negative regulator of cytokine receptor signaling, was lost in most IL-2 independent cell lines (3/4) but not in the leukemic ATLL cells (0/3). Finally, the HTLV-I(+) T-cell lines (313) but not the control, HTLV-I(-) T-cell lines were resistant to rapamycin and its novel analog RAD. We conclude that (1) HTLV-I infection per se does not result in a constitutive phosphorylation of the Jak3, STAT3, and STAT5 proteins; (2) malignant transformation in at least some cases of ATLL does not require the constitutive, but may require IL-2-induced, activation of the IL-2R Jak/STAT pathway; and (3) there are major differences in T-cell immortalization mechanism(s) which appear to involve SHP-1 and target molecules for rapamycin and RAD.

DNA-Binding Proteins↗
PubMed1999

Vg1 RBP intracellular distribution and evolutionarily conserved expression at multiple stages during development.

We have analyzed the expression and intracellular distribution, during oogenesis and embryogenesis, of Vg1 RBP, a protein implicated in the intracellular localization of Vg1 mRNA to the vegetal cortex of Xenopus oocytes. Vg1 RBP (protein) colocalizes with Vg1 RNA at all stages of oogenesis. Vg1 RBP RNA, however, localizes to the animal pole during late oogenesis, and remains in the animal blastomeres and ectodermal precursors until its zygotic transcription is activated, around stage 12. Vg1 RBP mRNA then becomes expressed throughout the neural epithelium. Vg1 RBP mRNA expression is also detected in what appears to be neural crest cells undergoing delamination and lateral migration. By tailbud stages, Vg1 RBP expression is present in the branchial arches, otic vesicle, pronephros, and along the neural tube. To examine the expression pattern in different species, we cloned the zebrafish homolog of Vg1 RBP by using a highly homologous EST clone to screen an embryonic cDNA library. In situ hybridization reveals that Vg1 RBP RNA localizes early in oogenesis to the animal pole. Although Vg1 RBP RNA is detected in all blastomeres of the early embryo, the expression pattern in the one day old zebrafish embryo is almost identical to that of the equivalent stage Xenopus embryo. These results indicate that the zygotic expression pattern is similar in frogs and fish, and that there is a conserved zygotic expression of Vg1 RBP distinct from its expression in the oocyte.

Amino Acid Sequence↗
PubMed1999

Randomized clinical trial comparing different iodine interventions in school children.

OBJECTIVE: The purpose of this trial was to compare three different iodine interventions. DESIGN: School children aged 8-10 years were randomized into one of three groups: group A was provided with iodized salt by researchers with an iodine concentration of 25 ppm; group B purchased iodized salt from the market; and group C was similar to group B with the exception that they were given iodized oil capsules containing 400 mg iodine at the beginning of the study. Salt iodine content was measured bimonthly for 18 months and indicators of iodine deficiency were measured at baseline and 6, 9, 12 and 18 months after randomization. RESULTS: The prevalence of abnormal thyroid volumes, based on the World Health Organization (WHO) body surface area reference >97th percentile, was 18% at baseline and declined to less than 5% by 12 months in groups A and C, and to 9% after 18 months in group B. Results for goitre by palpation were similar. The median urinary iodine was 94 microg l(-1) at baseline and increased in all groups to > 200 microg l(-1) at the 6-month follow-up. CONCLUSIONS: In this population of school children with initially a low to moderate level of iodine deficiency, the group receiving salt with 25 ppm (group A) was not iodine deficient on all indicators after 18 months of study. When the iodine content of the salt varied, such as in group B, by 18 months thyroid sizes had not yet achieved normal status.

Child↗
PubMed1999

Oxidation of diazinon by aqueous chlorine: kinetics, mechanisms, and product studies.

The oxidation kinetics and mechanisms of diazinon, an organophosphorus pesticide, by aqueous chlorine were studied under different conditions. The oxidation is of first order with respect to both diazinon and chlorine. The oxidation rate is found to increase with decreasing pH. The second-order rate constants at pH 9. 5, 10.0, 10.5, and 11.0 are determined to be 1.6, 0.64, 0.43, and 0. 32 M(-)(1) s(-)(1), respectively. Based on the rate constants at different temperatures, the activation energy is calculated to be 30 kJ/mol at pH 10.0 with a chlorine-to-diazinon ratio of 11:1, 33 kJ/mol at pH 11.0 with a 11:1 ratio, and 36 kJ/mol at pH 11.0 with a 5:1 ratio, respectively. Diazoxon is identified as the oxidation product by GC-MS. Ion chromatography analysis shows an increase of sulfate concentration as the reaction proceeds, indicating that sulfur is being oxidized to sulfate. This study indicates that oxidation by aqueous chlorine can significantly affect the fate of diazinon in the environment.

Chlorine↗
PubMed1999

Five new triterpene saponins from Pulsatilla patens var. multifida.

Five new oleanane-type glycosides (1-5), along with two known triterpene saponins, were isolated from the roots of Pulsatilla patens var. multifida (Ranunculaceae). The structures of the new triterpene saponins were elucidated as 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranosyl hederagenin 28-O-beta-D-glucopyranosyl ester (1), hederagenin 3-O-[beta-D-glucopyranosyl(1-->2)][beta-D-glucopyranosyl(1-->6)]-beta -D-galactopyranoside (2), 3-O-beta-D-glucopyranosyl bayogenin 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta -D-glucopyranosyl ester (3), 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranosyl oleanolic acid 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta -D-glucopyranosyl ester (4), and 3-O-[beta-D-glucopyranosyl(1-->2)][beta-D-glucopyranosyl(1-->6)]-beta -D-galactopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta -D-glucopyranosyl ester (5). Structure elucidation was accomplished by 1D and 2D NMR (HMQC, HMBC, and ROESY) methods, FABMS, and hydrolysis.

Carbohydrate Sequence↗
PubMed1999

Immunological response in chronic fatigue syndrome following a graded exercise test to exhaustion.

This study was conducted to evaluate the immunological response to an exhaustive treadmill exercise test in 20 female chronic fatigue syndrome patients compared to 14 matched sedentary controls. Venipuncture was performed at baseline and 4 min, 1 hr, and 24 hr postexercise. White blood cells were labeled for monoclonal antibody combinations and were quantified by FACsan. Cytokines were assayed utilizing quantitative RT/PCR. No group difference was seen in VO2peak (28.6 +/- 1.6 vs 30.9 +/- 1.2 ml.kg-1.min-1; P > 0.05). However, 24 hr after exercise the patients' fatigue levels were significantly increased (P < 0.05). The counts of WBC, CD3+ CD8+ cells, CD3+ CD4+ cells, T cells, B cells, natural killer cells, and IFN-gamma changed across time (P's < 0.01). No group differences were seen for any of the immune variables at baseline or after exercise (P's > 0.05). The immune response of chronic fatigue syndrome patients to exhaustive exercise is not significantly different from that of healthy nonphysically active controls.

Adult↗
PubMed1999

Solution structure of the extended neuronal nitric oxide synthase PDZ domain complexed with an associated peptide.

The PDZ domain of neuronal nitric oxide synthase (nNOS) functions as a scaffold for organizing the signal transduction complex of the enzyme. The NMR structure of a complex composed of the nNOS PDZ domain and an associated peptide suggests that a two-stranded beta-sheet C-terminal to the canonical PDZ domain may mediate its interaction with the PDZ domains of postsynaptic density-95 and alpha-syntrophin. The structure also provides the molecular basis of recognition of Asp-X-Val-COOH peptides by the nNOS PDZ domain. The role of the C-terminal extension in Asp-X-Val-COOH peptide binding is investigated. Additionally, NMR studies further show that the Asp-X-Val-COOH peptide and a C-terminal peptide from a novel cytosolic protein named CAPON bind to the same pocket of the nNOS PDZ domain.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Inactivating mutations and overexpression of BCL10, a caspase recruitment domain-containing gene, in MALT lymphoma with t(1;14)(p22;q32).

Mucosa-associated lymphoid tissue (MALT) lymphomas most frequently involve the gastrointestinal tract and are the most common subset of extranodal non-Hodgkin lymphoma (NHL). Here we describe overexpression of BCL10, a novel apoptotic signalling gene that encodes an amino-terminal caspase recruitment domain (CARD), in MALT lymphomas due to the recurrent t(1;14)(p22;q32). BCL10 cDNAs from t(1;14)-positive MALT tumours contained a variety of mutations, most resulting in truncations either in or carboxy terminal to the CARD. Wild-type BCL10 activated NF-kappaB but induced apoptosis of MCF7 and 293 cells. CARD-truncation mutants were unable to induce cell death or activate NF-kappaB, whereas mutants with C-terminal truncations retained NF-kappaB activation but did not induce apoptosis. Mutant BCL10 overexpression might have a twofold lymphomagenic effect: loss of BCL10 pro-apoptosis may confer a survival advantage to MALT B-cells, and constitutive NF-kappaB activation may provide both anti-apoptotic and proliferative signals mediated via its transcriptional targets.

Adaptor Proteins, Signal Transducing↗