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Biomedical subjects

K Wu

Publications and source records attributed to K Wu.

At least 55 records · Page 3Linked to original sources
PubMed2001

Activation of nuclear factor-kappa b transcriptional activity in airway epithelial cells by thioredoxin but not by N-acetyl-cysteine and glutathione.

Increasing evidence indicates that intracellular redox status modulates the activity of various transcriptional factors, including nuclear factor (NF)-kappa B and activator protein-1. Our laboratory has been interested in characterizing the role thioredoxin (TRX) plays in regulating cellular redox status in airway epithelium. TRX is a small, ubiquitous protein with two redox-active half-cysteine residues, -Cys-Gly-Pro-Cys, in its active center. Using primary passage-1 human tracheobronchial epithelial cell cultures and an immortalized human bronchial epithelial cell line, HBE1, we observed that tumor necrosis factor (TNF)-alpha enhanced NF-kappa B transcriptional activity. This observation was based on gel mobility shift assays and interleukin (IL)-8 promoter-reporter gene transfection studies. TNF-alpha activation coincided with translocation of NF-kappa B p65 from the cytoplasm to the nucleus. Pretreatment with N-acetyl-cysteine (NAC) (1 to 10 mM) or glutathione (1 to 10 mM) inhibited TNF-alpha-induced activation of NF-kappa B transcriptional activity and IL-8 promoter-mediated reporter gene expression. In contrast, elevated TRX protein levels in cells enhanced TNF-alpha-dependent NF-kappa B transcriptional activity and IL-8 promoter activity. This observation was independent of the manner in which TRX was elevated in cells (e.g., by cotransfection with a FLAG-TRX expression clone, or by direct exposure to commercially available human TRX protein). Localization of TRX protein by anti-TRX antibody indicated an accumulation of TRX protein in the nucleus after TNF-alpha treatment. The nuclear localization phenomenon was different from the major cytosolic accumulation of glutathione and NAC. This is the first known report demonstrating movement of TRX into the nucleus of airway epithelial cells after an inflammatory stress. These results suggest a compartment effect of thiol chemicals in the regulation of redox-dependent transcriptional activity.

Acetylcysteine↗
PubMed2001

Aromatase p450 expression in a feminizing adrenal adenoma presenting as isosexual precocious puberty.

A 7-yr-old girl presented with isosexual precocious puberty secondary to a feminizing adrenal adenoma. The adrenal tumor was found to express aromatase messenger ribonucleic acid. Enzyme kinetic studies revealed a high level of aromatase activity in the adrenal tumor, with a K(m) of 45 nmol/L and a maximum velocity of 25.6 pmol/mg.h. Aromatase activity was approximately 500-fold higher in the tumor than in adjacent normal adrenal tissue. Although histopathological examination of the tumor was most consistent with a benign adenoma, the aromatase transcripts present in the tumor corresponded to those previously associated with malignant as well as benign tumors. We consider the pattern of aromatase expression sufficient to warrant continued follow-up for tumor recurrence. Our case demonstrates that isosexual precocious puberty secondary to a feminizing adrenal tumor can be due to estrogen synthesis from the tumor itself rather than peripheral aromatization as had been previously theorized.

Adenoma↗
PubMed2001

Inhibitory effects of RRR-alpha-tocopheryl succinate on benzo(a)pyrene (B(a)P)-induced forestomach carcinogenesis in female mice.

AIM: To study the inhibitory effects of VES (RRR-alpha-tocopheryl Succinate, VES),a derivative of natural Vitamin E, on benzo(a)pyrene(B(a)P)-induced forestomach tumor in female mice. METHODS: The model of B(a)P-induced forestomach tumor was established according to the methods of Wattenberg with slight modify-cations. One hundred and eighty female mice (6 weeks old) were divided into six groups equally; negative control (Succinic acid), vehicle control (Succinate+B(a)P),positive control(B(a)P), high VES(2.5 g/kg.b.w+B(a)P), low VES(1.25 g/kg.b.w+B(a)P)ig as well as VES by ip (20 mg/kg.b.w+B(a)P). Except the negative control group, the mice were administrated with B(a)P ig. and corresponding treatments for 4 weeks to study the anti-carcinogenetic effect of VES during the initiation period. The experiment lasted 29 weeks, in which the inhibitory effects of VES both on tumor incidence and tumor size were tested. RESULTS: The models of B(a)P-induced forestomach tumor in female mice were established successfully. Some were cauliflower-like, others looked like papilla, even a few were formed into the ulcer cavities. VES at 1.25 g/kg.b.w, 2.5 g/kg.b.w. by ig and 20 mg/kg.b.w. via ip could decrease the number of tumors per mouse (1.7 plus minus 0.41, 1.6 plus minus 0.34 and 1.1 +/- 0.43), being lower than that of B(a)P group (5.4 +/- 0.32, P<0.05). The tumor incidence was inhibited by 18.2%, 23.1% and 50.0%. VES at 1.25 g/kg.b.w., 2.5 g/kg.b.w. by ig and 20 mg/kg.b.w. via ip reduced the total volume of tumors per mouse (54.8 +/- 8.84, 28.4 8 +/- 8.32 and 23.9 8 +/- 16.05), being significantly lower than that of B(a)P group (150.2 8 +/- 20.93, P < 0.01). The inhibitory rates were 63.5%, 81.1% and 84.1%, respectively. CONCLUSION: VES has inhibitory effects on B(a)P-induced forestomach carcinogenesis in female mice, especially by ip and it may be a potential anti-cancer agent in vivo.

Animals↗
PubMed2001

Arsenic contamination of groundwater and prevalence of arsenical dermatosis in the Hetao plain area, Inner Mongolia, China.

An investigation was carried out on arsenic contamination of groundwater and prevalence of arsenical dermatosis in the Hetao plain of Inner Mongolia Autonomous Region, China. Based on the screening of water samples from 96 randomly selected wells in this Region, two areas (Wuyuan and Alashan) were chosen as highly contaminated areas because arsenic in the water samples was higher than 50 microg/l. Arsenic was measured using an arsenic silver diethyl dithiocarbamate method for 326 water samples from all the wells in these areas. The results show arsenic contaminated groundwater from tubule-type wells of depths about 15-30 m was serious compared with open-type wells where depth is about 3-5 m. In the Wuyuan area, 96.2% of water samples from tubule-type wells contained arsenic above 50 microg/l and 69.3% in Alashan area; the highest value was 1354 microg/l and 1088 microg/l, respectively. In these two areas, a health survey was carried out for arsenical dermatosis. The results show the prevalence of arsenical dermatosis in the Wuyuan area was 44.8%, higher than 37.1% prevalence of arsenical dermatosis in the Alashan area. The prevalence of arsenical dermatosis was highest in the over 40-year-old age group. There was no sex difference in the prevalence. Further investigation is needed to clarify the actual situation of arsenic pollution of groundwater in Inner Mongolia, China in order to reduce the adverse health effect among residents exposed to arsenic.

Adolescent↗
PubMed2001

Characterization of hemagglutinin gene of influenza A virus subtype H9N2.

OBJECTIVE: To determine the origin of human influenza A (H9N2) virus and the relationship among H9N2 strains isolated from different hosts, on the basis of molecular biology. METHODS: Viruses were passed in embryonated hen eggs, and virion RNA was extracted from allantoic fluid and reverse transcribed to synthesize cDNA. cDNA was amplified by PCR and the PCR product was purified with a purification kit. Afterwards RNA sequence analysis was performed by dideoxynucleotide chain termination and a cloning method. Finally, phylogenetic analysis of the sequencing data was performed with MegAlign (version 1.03) and Editseg (version 3.69) softwares. RESULTS: The amino acid sequences at the cleavage site between HA1 and HA2 domains of H9N2 viruses isolated in China are R-S-S-R. One pigeon strain contains seven potential glycosylation sites on the HA protein molecule, while all others have eight. There are 2 to 15 differences of amino acid sequences distributed at 24 different positions on the HA protein molecules among six H9N2 viruses. The H9N2 viruses with multiple lineages of HA genes were co-circulating in China recently. CONCLUSION: The highest possibility is that human influenza A (H9N2) virus was derived from Chicken H9N2 virus, and not derived from pigeon H9N2 virus. However, it is still unknown whether the H9N2 virus could transmit from person to person. The H9N2 viruses with multiple lineages of HA genes are co-circulating in China.

Amino Acid Sequence↗
PubMed2001

Detection of human herpesvirus 8 DNA in acute leukemia patients.

OBJECTIVE: To determine the prevalence of human herpesvirus 8 (HHV-8) DNA in acute leukemia (AL) patients. METHODS: The presence of HHV-8 DNA sequences in peripheral blood mononuclear cells (PBMC) and bone marrow mononuclear cells (BMMC) from 50 AL patients was examined using polymerase chain reaction (PCR). Nine human hematopoietic cell lines and PBMC from 30 normal donors were also included. RESULTS: HHV-8 DNA sequences were detected in one case of acute myelogenous leukemia (AML). The specimens from the bone marrow aspirate, peripheral blood and serum of this patient were all positive. None of the normal donors and human hematopoietic cell lines showed evidence of HHV-8 DNA. CONCLUSION: The results suggest that the prevalence of HHV-8 is low in AL in China.

Acute Disease↗
PubMed2001

[Significance of lung perfusion scanning with technetium labeled macroaggregated albumin and pulmonary function assay for diagnosis of early hepatopulmonary syndrome].

OBJECTIVE: To evaluate the values of pulmonary function assay and dynamic pulmonary perfusion imaging with technetium labeled macroaggregated albumin ((99m)TcMAA) in the early diagnosis of hepatopulmonary syndrome (HPS). METHODS: The pulmonary function assay and (99m)TcMAA scans were performed in 28 patients with HPS, 30 cirrhotic patients (CP) without HPS, and 21 healthy controls (HC). RESULTS: In the patients with HPS, PaO(2), SaO(2) and diffusion capacity for carbon monoxide of lungs (DLco) was significantly lower than that in CP (P<0.01) and HC (P<0.01), and alveolar-arterial gradient [P((A-a))O(2)] was significantly increased (P<0.001). Results from (99m)TcMAA scans showed that the radionuclides were distributed over the spleen, kidney, liver and brain, and the ratios of arterivenous shunt were significantly higher than that in CP (P<0.001) and NC (P<0.001). In cirrhotic patients, DLco significantly decreased (P<0.05), P((A-a))O(2) and shunt ratios increased (P<0.01 and 0.001). CONCLUSIONS: Pulmonary function assay and dynamic pulmonary perfusion imaging with (99m)TcMAA are sensitive methods for diagnosis of the early HPS.

Hepatopulmonary Syndrome↗
PubMed2001

[The effect of calponin and caldesmon in regulation of the gastrointestinal motility during pathophysiological adaptation].

OBJECTIVE: To investigate the expression of calponin (CaP) and caldesmon (CaD) in the gastrointestinal tract and their effect in regulating gastrointestinal motility during physiological and pathological adaptation. METHODS: Models of chronic gastrointestinal motility hyperfunction in mice were induced by intragastric administration of senna extraction and models of chronic gastrointestinal motility hypofunction in rats were established with carbon tetrachloride induced cirrhosis, CaP and CaD were detected in the gastrointestinal tract of different model groups using SDS-PAGE and Western blot. The color development of Western blots was scanned using densitometric scanning. The relative contents of gastrointestinal CaP and CaD were compared with control animals with different state of gastrointestinal motility. RESULTS: Animal models of abnormal gastrointestinal motility were established in mice and rats. Densitometric quantification of CaP and CaD blots by CP1 and C98 mAbs showed that normal animal colon contained higher amounts of h1-CaP and CaD. In normal mice and rats, the content of CaP and CaD was successively in this order :colon > stomach > small intestine. The content was reduced in mice of chronic gastrointestinal motility hyperfunction, but the expression of CaP and CaD was promoted in rats with cirrhosis and declined to normal level after treatment with L-NAME. CONCLUSION: There is close relation between expression of CaP and CaD and state of gastrointestinal motility. CaP and CaD may inhibit gastrointestinal motility. These suggest that CaP and CaD may play a role in the regulation of gastrointestinal motility during physiological and pathological adaptation.

Animals↗
PubMed2001

[Preliminary study on the rules of streptococcus mutans reactive oxygen species metabolism].

OBJECTIVE: To study the rules of Streptococcus mutans reactive oxygen species metabolism and its enzymatic basis, and to investigate its significance intermediate to plaque microbial ecology. METHODS: Electron spin trapping method was used to measure reactive oxygen species produced by Streptococcus mutans in the different incubation conditions, and evaluate the efficicay of NADH to hypoxanthine-xanthine oxidase and Fe(2+)-H2O2 system. RESULTS: Electron spin resonance (ESR) spectrum of DMPO-O2- and DMPO-OH. and superoxide dismutase were obtained in Streptococcus mutans culture fluid, these spectrum were strengthened by exogenous sugar, and disappeared when methylene blue was added to culture fluid, but that spectrum was not significantly changed by NADH. ESR spectrum of hypoxanthine-xanthine oxidase and Fe(2+)-H2O2 system were significantly reduced or disappeared by NADH. CONCLUSION: These results suggest that there are O2- and OH in Streptococcus mutans metabolism, and they may come mainly from the reaction catalyzed by NADH oxidase.

Electron Spin Resonance Spectroscopy↗
PubMed2001

[Patient awareness study of elderly population in rural Guangdong].

OBJECTIVE: To investigate the patients' awareness on the eye diseases, treatment and major barriers for patients to seek eye care. METHOD: Randomly clustering sampling method was used for all the subjects aged 50 years and over, and their eyes were examined. All subjects with presenting visual acuity less than 0.1 in at least one eye underwent the test of the patient's awareness questionnaire developed in Aravind Eye Hospital, India. RESULTS: Five hundred and thirty-five (85.5%) visual impairment subjects were successfully interviewed. In 526 cases with the ocular disease course over 1 year, 95% of them were aware of the occurrence of eye diseases for more than 1 year. However, in the 448 cases with the ocular diseases treatable, only 24.2% of them realized that their eye diseases could be treated, while 73% of them did not know or did know right on the examination date. The major barriers for seeking eye care were economic reason, fear of operation, far distance from a hospital, etc. CONCLUSION: Patients' education and low price service are probably the effective methods to clear the roadblock on the way of improving the coverage of eye care.

Age Distribution↗
PubMed2001

[Studies on characteristics of kinetics and metabolic shift of genetically engineered yeast Pichia pastoris in high-density chemostat cultivation].

Kinetics and metabolic shift of DNA recombinant yeast Pichia pastoris was studied in high-density chemostat cultivation in which the glycerol was used as a limited substrate. The experimental results showed that (1) cell optical density (OD600) of Pichia pastoris was linear with its dry cell weight (DCW) and wet cell weight (WCW), and reached 100 OD600 = 128.3 g WCW/L or 100 OD600 = 22.9 g DCW/L; (2) The relationship of specific growth rate (mu) and residual concentration of glycerol is accorded with Monod Equation, to obtain mu = mumax S/(Ks + S), where mumax = 0.366 h-1, Ks = 0.1823 g/L. The maximum cell yield of glycerol substrate YG = 0.54 g/g, growth maintaining coefficient m = 0.0069 g/(g.h), The cell yield of oxygen YX/O2 = 30.96 g/moL, and the optimum theoretical dilution rate Dm = 0.341 h-1 by parameter inference; (3) With specific growth rate (mu) increasing, glycerol metablic flux shifts linearly from glycogenesis and hexosephosphate pathways to glycolysis and tricarboxylic acid cycle pathways on basis of variations of consumption rate of NH3.H2O and respiratory quotient value.

Biotechnology↗
PubMed2001

[Effects of glutamine on the intestinal failure in rats model of acute necrotizing pancreatitis].

OBJECTIVE: To determine the effects of glutamine (Gln) on the intestinal failure in rats with acute necrotizing pancreatitis (ANP) and its possible mechanisms. METHODS: Fifty-four Sprague-Dawley rats were randomly divided into 3 groups: sham operation (SO, n = 18), ANP (n = 18), and ANP treated with Gln (ANP + Gln, n = 18). ANP model was induced by injection of 5% sodium taurocholate solution into bilo-pancreatic duct. The therapy was continuously given with amino acid solution by a mini-pump via a central intravenous line. In addition, the ANP + Gin group was received 3% Gln dipeptide solution (equal to 2% Gln) with a dosage of 0.5g x kg(-1) x d(-1). These groups were isocaloric and isonitrogenous. Bacterial cultures from pancreas, mesenteric lymph node (MLN), liver, spleen and ascites were done at 24, 48, 72 h after operation. Endotoxin level in portal vein was determined. Pathologic changes of intestinal mucosa were also studied. Apoptosis of intestinal mucosa was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method. Expressions of insulin-like growth factor 1 (IGF-1), Gln synthetase (GSase) and glutaminase (Glnase) mRNA were assayed by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: At 24, 48, 72h, the positive rate of bacterial culture and the endotoxin concentration were increased significantly in ANP group compared to the SO group (P < 0.05), while Gln could decrease them significantly. Pathologic study showed that the height of mucosal villous in ANP group was lower than that in SO group, indicating the intestinal mucosa became more atrophy. However, the height of mucosal villous in ANP + Gln group was no significantly difference compared to that in SO group, indicated Gln could preserve the mucosa well. Apoptotic index was increased in ANP group and decreased in Gln treated rats. Expressions of IGF-1, GSase, Glnase mRNA were down-regulated in ANP group, but were up-regulated in ANP + Gln group. CONCLUSIONS: The intestinal barrier function was impaired in ANP. Gln could protect intestinal barrier function. This action was probably related to its enhancement of IGF-1, GSase and Glnase mRNA expressions and its inhibition of intestinal mucosal apoptosis.

Animals↗
PubMed2000

Induction of the BRCA2 promoter by nuclear factor-kappa B.

BRCA2 is a tumor suppressor gene that has been implicated in response to DNA damage, cell cycle control, and transcription. BRCA2 has been found to be overexpressed in many breast tumors, suggesting that altered expression of the BRCA2 gene may contribute to breast tumorigenesis. To determine how BRCA2 is overexpressed in tumors, we investigated the transcriptional regulation of the BRCA2 promoter. Deletion mapping of the BRCA2 promoter identified three regions associated with 3-fold activation or repression and one upstream stimulatory factor binding site associated with 20-fold activation. Gel shift and cotransfection studies verified the role of USF in regulation of BRCA2 transcription. Analysis of the -144 to -59 region associated with 3-fold activation identified a putative NFkappaB binding site. Cotransfection of the p65 and p50 subunits of NFkappaB up-regulated the BRCA2 promoter 16-fold in a luciferase reporter assay, whereas mutations in the binding site ablated the effect. Gel shift and supershift assays with anti-p65 and -p50 antibodies demonstrated that NFkappaB binds specifically to the NFkappaB site. In addition, ectopic expression of NFkappaB resulted in increased levels of endogeneous BRCA2 expression. Thus, NFkappaB and USF regulate BRCA2 expression through the BRCA2 promoter.

BRCA2 Protein↗
PubMed2000

Telomerase activity is increased and telomere length shortened in T cells from blood of patients with atopic dermatitis and psoriasis.

We studied telomerase activity and telomere length in PBMC and purified CD4(+) and CD8(+) T cells from blood obtained from a total of 32 patients with atopic dermatitis, 16 patients with psoriasis, and 30 normal controls. The telomerase activity was significantly increased in PBMC from the patients compared with PBMC from normal donors. This increase was most pronounced in the subpopulation of CD4(+) T cells, which were significantly above the activity of the CD8(+) T cells in atopic dermatitis, psoriasis patients, and control persons. The telomere length was significantly reduced in all T cell subsets from both atopic dermatitis and psoriasis patients compared with normal individuals. Furthermore, the telomere length was found to be significantly shorter in CD4(+) memory T cells compared with the CD4(+) naive T cells, and both of the cell subsets from diseases were shown to be of significantly shorter telomere length than the same cell subsets from normal controls. No significant difference was observed between CD8(+)CD28(-) and CD8(+)CD28(+) T cell populations in both diseases. However, the telomere length of CD8(+)CD28(+) T cells from both diseases was significantly shorter than CD8(+)CD28(+) T cell subsets from normal donors. In conclusion, the increased telomerase activity and shortened telomere length indicates that T lymphocytes in atopic dermatitis and psoriasis are chronically stimulated and have an increased cellular turnover in vivo.

Adolescent↗
PubMed2000

Conjugation of Nedd8 to CUL1 enhances the ability of the ROC1-CUL1 complex to promote ubiquitin polymerization.

The SCF-ROC1 ubiquitin-protein isopeptide ligase (E3) ubiquitin ligase complex targets the ubiquitination and subsequent degradation of protein substrates required for the regulation of cell cycle progression and signal transduction pathways. We have previously shown that ROC1-CUL1 is a core subassembly within the SCF-ROC1 complex, capable of supporting the polymerization of ubiquitin. This report describes that the CUL1 subunit of the bacterially expressed, unmodified ROC1-CUL1 complex is conjugated with Nedd8 at Lys-720 by HeLa cell extracts or by a purified Nedd8 conjugation system (consisting of APP-BP1/Uba3, Ubc12, and Nedd8). This covalent linkage of Nedd8 to CUL1 is both necessary and sufficient to markedly enhance the ability of the ROC1-CUL1 complex to promote ubiquitin polymerization. A mutation of Lys-720 to arginine in CUL1 eliminates the Nedd8 modification, abolishes the activation of the ROC1-CUL1 ubiquitin ligase complex, and significantly reduces the ability of SCF(HOS/beta)(-TRCP)-ROC1 to support the ubiquitination of phosphorylated IkappaBalpha. Thus, although regulation of the SCF-ROC1 action has been previously shown to preside at the level of recognition of a phosphorylated substrate, we demonstrate that Nedd8 is a novel regulator of the efficiency of polyubiquitin chain synthesis and, hence, promotes rapid turnover of protein substrates.

Amino Acid Substitution↗
PubMed2000

The FK520 gene cluster of Streptomyces hygroscopicus var. ascomyceticus (ATCC 14891) contains genes for biosynthesis of unusual polyketide extender units.

FK520 (ascomycin) is a macrolide produced by Streptomyces hygroscopicus var. ascomyceticus (ATCC 14891) that has immunosuppressive, neurotrophic and antifungal activities. To further elucidate the biosynthesis of this and related macrolides, we cloned and sequenced an 80kb region encompassing the FK520 gene cluster. Genes encoding the three polyketide synthase (PKS) subunits (fkbB, fkbC and fkbA), the peptide synthetase (fkbP), the 31-O-methyltransferase (fkbM), the C-9 hydroxylase (fkbD) and the 9-hydroxyl oxidase (fkbO) had the same organization as the genes reported in the FK506 gene cluster of Streptomyces sp. MA6548 (Motamedi, H., Shafiee, A., 1998. The biosynthetic gene cluster for the macrolactone ring of the immunosuppressant FK506. Eur. J. Biochem. 256, 528-534). Disruption of a PKS gene in the cluster using the &phi;C31 phage vector, KC515, led to antibiotic non-producing strains, proving the identity of the cluster. Previous labeling data have indicated that FK520 biosynthesis uses novel polyketide extender units (Byrne, K.M., Shafiee, A., Nielson, J., Arison, B., Monaghan, R.L., Kaplan, L., 1993. The biosynthesis and enzymology of an immunosuppressant, immunomycin, produced by Streptomyces hygroscopicus var, ascomyceticus. Dev. Ind. Microbiol. 32, 29-45). Genes in the flanking regions of the FK520 cluster were identified that appear to be involved in synthesis of these extender units. All but two of these genes were homologous to genes with known function. In addition to a crotonyl-CoA reductase gene (fkbS), at least two other genes are proposed to be involved in biosynthesis of the atypical PKS extender unit ethylmalonyl-CoA, which accounts for the ethyl side chain on C-21 of FK520. A set of five contiguous genes (fkbGHIJK) is proposed to be involved in biosynthesis of an unusual PKS extender unit bearing an oxygen on the alpha-carbon, and leading to the 13- and 15-methoxy side chains. These putative precursor synthesis genes in the flanking regions of the FK520 cluster are not found in the flanking regions of the rapamycin cluster (Molnár, I., Aparicio, J.F., Haydock, S.F., Khaw, L.E., Schwecke, T., König, A., Staunton, J., Leadlay, P.F., 1996. Organisation of the biosynthetic gene cluster for rapamycin in Streptomyces hygroscopicus: analysis of genes flanking the polyketide synthase. Gene 169, 1-7), consistent with labeling data showing that rapamycin biosynthesis uses only malonyl and methylmalonyl extender units.

Acyl Coenzyme A↗