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Sample records for acid oxidase lao

  1. Cytotoxic L-amino-acid oxidases from Amanita phalloides and Clitocybe geotropa induce caspase-dependent apoptosis

    PubMed Central

    Pišlar, A; Sabotič, J; Šlenc, J; Brzin, J; Kos, J

    2016-01-01

    L-amino-acid oxidases (LAO) purified from fungi induce cell death in various mammalian cells including human tumor cell lines. The mechanism, however, remains poorly understood. In this study, we aimed to define a precise mechanism of cell death induced in Jurkat and MCF7 cancer cell lines by ApLAO and CgLAO, LAOs isolated from Amanita phalloides and Clitocybe geotropa, respectively. Cell death induced by both LAOs is shown to be concentration- and time-dependent, with higher toxic effects in Jurkat cells. LAO activity is required for the cytotoxicity. Detailed study on Jurkat cells further demonstrated that ApLAO and CgLAO both induce the intrinsic mitochondrial pathway of apoptosis, accompanied by a time-dependent depolarization of the mitochondrial membrane through the generation of reactive oxygen species. Treatment with the LAOs resulted in an increased ratio of the expression of proapoptotic Bax to that of antiapoptotic Bcl-2, subsequently leading to the activation of caspase-9 and -3. However, the pancaspase inhibitor, Z-VAD-FMK, did not completely abolish the cell death induced by either ApLAO or CgLAO, suggesting an alternative pathway for LAO-induced apoptosis. Indeed, caspase-8 activity in ApLAO- and CgLAO-treated cells was increased. Further, Fas/FasL (Fas ligand) antagonist caused a slight reduction in toxin-induced cell death, supporting the involvement of ApLAO and CgLAO in death-receptor-mediated apoptosis. These results thus provide new evidence that ApLAO and CgLAO induce apoptosis in Jurkat cells via both the intrinsic and extrinsic pathways, although the significantly higher increase of caspase-9 over caspase-8 activity suggests that it is the intrinsic pathway that is the predominant mode of ApLAO- and CgLAO-induced apoptosis. PMID:27551514

  2. Low expression of the antibacterial factor L-amino acid oxidase in bovine mammary gland.

    PubMed

    Nagaoka, Kentaro; Zhang, Haolin; Arakuni, Masahiro; Taya, Kazuyoshi; Watanabe, Gen

    2014-12-01

    In the mouse, L-amino acid oxidase (LAO) produces hydrogen peroxide by utilizing free amino acids and is a proven antibacterial factor in mammary glands. Mastitis, a bacterial infection of the mammary gland, is the most frequent disease in dairy cattle. Here, we investigate whether LAO is expressed in the mammary gland of dairy cattle and is antibacterial. In dairy cattle, the expression level of LAO mRNA in the mammary gland was considerably lower than that in mice, and LAO activity was not observed in cattle milk that produced hydrogen peroxide. The expression of LAO mRNA was also low in Japanese Black cattle, the same as in Holstein cattle. A higher LAO mRNA expression was observed in the mastitis glands than in the lactating glands. Furthermore, spleen and lymph nodes expressed high levels of LAO mRNA in dairy cattle. We conclude that mammary glands in dairy cattle have lower ability to express the LAO gene compared to that in mice, which may result in a high incidence of mastitis.

  3. Identification of the Atlantic cod L-amino acid oxidase and its alterations following bacterial exposure.

    PubMed

    Kitani, Yoichiro; Fernandes, Jorge M O; Kiron, Viswanath

    2015-06-01

    Antibacterial factors that are present in epidermal mucus of fish have a potential role in the first line of host defence to bacterial pathogens. This study reports the identification of L-amino acid oxidase (LAO) in Atlantic cod (GmLao) and the changes in the molecule following bacterial exposure. The gmlao transcripts and LAO activity were present on both the body surface and in the internal organs of the fish. Relative mRNA level of gmlao increased significantly in the gills, the spleen and the head kidney (up to 8-fold) of fish that were challenged with the pathogen Vibrio anguillarum. The gmlao expression in skin was 4-fold higher in challenged fish. Our data indicate that LAO may be an important effector of antibacterial defence in Atlantic cod.

  4. Screening of Bothrops snake venoms for L-amino acid oxidase activity

    SciTech Connect

    Pessati, M.L.; Fontana, J.D.; Guimaraes, M.F.

    1995-12-31

    Toxins, enzymes, and biologically active peptides are the main components of snake venoms from the genus Bothrops. Following the venom inoculation, the local effects are hemorrhage, edema, and myonecrosis. Nineteen different species of Brazilian Bothrops were screened for protein content and L-amino acid oxidase activity. B. cotiara, formerly found in the South of Brazil, is now threatened with extinction. Its venom contains a highly hemorrhagic fraction and, as expected from the deep yellow color of the corresponding lyophilized powder, a high L-amino acid oxidase (LAO) activity was also characterized. Flavin adenine dinucleotide (FAD) is its associate coenzyme. B. cotiara venom LAO catalyzed the oxidative deamination of several L-amino acids, and the best substrates were methionine, leucine, tryptophan, and phenylalanine, hence, its potential application for the use in biosensors for aspartame determination and for the removal of amino acids from plasma. High levels for LAO were also found in other species than B. cotiara. In addition, the technique of isoelectric focusing (IEF) was employed as a powerful tool to study the iso- or multi-enzyme distribution for LAO activity in the B. cotiara snake venom.

  5. Cloning and characterization of the gene for L-amino acid oxidase in hybrid tilapia.

    PubMed

    Shen, Yubang; Fu, Gui Hong; Liu, Feng; Yue, Gen Hua

    2015-12-01

    Tilapia is the common name for a group of cichlid fishes. Identification of DNA markers significantly associated with important traits in candidate genes may speed up genetic improvement. L-Amino acid oxidase (LAO) plays a crucial role in the innate immune defences of animals. Previously, whether LAO variants were associated with economic traits had not been studied in fish. We characterized the cDNA sequence of the LAO gene of hybrid tilapia (Oreochromis spp.). Its ORF was 1536 bp, encoding a flavoenzyme of 511 amino acids. This gene consisted of seven exons and six introns. Its expression was detected in the intestine, blood, kidney, skin, liver. It was highly expressed in the intestine. After a challenge with a bacterial pathogen, Streptococcus agalactiae, its expression was up-regulated significantly in the liver, intestine and spleen (P < 0.05). We identified one SNP in the genomic sequence of the gene and found that this SNP was associated significantly with body length (P < 0.05), but not with resistance to S. agalactiae. The results of this study suggest that the LAO gene plays an important role in innate immune responses to the bacterial pathogen in tilapia. The investigation of relationship between polymorphism of LAO gene and disease resistance and growth in tilapia showed that one SNP was associated significantly with body length. Further experiments on whether SNPs in the LAO gene are associated with growth in tilapia and other populations could be useful in understanding more functions of the LAO gene.

  6. Gene expression and distribution of antibacterial L-amino acid oxidase in the rockfish Sebastes schlegeli.

    PubMed

    Kitani, Yoichiro; Mori, Tsukasa; Nagai, Hiroshi; Toyooka, Keiko; Ishizaki, Shoichiro; Shimakura, Kuniyoshi; Shiomi, Kazuo; Nagashima, Yuji

    2007-12-01

    Antibacterial factors in the epidermal mucus of fish have a potential importance in the first line of the host defense response to bacterial pathogens. We previously isolated a novel antibacterial protein termed SSAP (Sebastes schlegeli antibacterial protein) from the skin mucus of the rockfish S. schlegeli and identified it as a new member of the L-amino acid oxidase (LAO) family. In the present study, the localization of SSAP in S. schlegeli was investigated by reverse transcription (RT)-PCR, quantitative real time RT-PCR, Western blotting and measurements of LAO and antibacterial activities. SSAP mRNA was expressed dominantly in skin and gill and weakly in ovary or kidney as shown by RT-PCR and real time RT-PCR. The quantity of SSAP mRNA in skin varied among the individuals, ranging from 1.1 to 13.9 ng microg(-1) total RNA, although no relationship was found between the size of fish and gene expression. SSAP was exclusively detected in skin and gill by Western blotting using a specific anti-SSAP antiserum. In addition, the extracts of both tissues apparently showed LAO activity and antibacterial activity against Photobacterium damselae subsp. piscicida. This study demonstrates that SSAP is predominantly synthesized in skin and gill and probably functions as an antibacterial LAO in both tissues.

  7. THE PREPARATION AND PROPERTIES OF HIGHLY PURIFIED ASCORBIC ACID OXIDASE

    PubMed Central

    Powers, Wendell H.; Lewis, Stanley; Dawson, Charles R.

    1944-01-01

    1. A method is described for the preparation of a highly purified ascorbic acid oxidase containing 0.24 per cent copper. 2. Using comparable activity measurements, this oxidase is about one and a half times as active on a dry weight basis as the hitherto most highly purified preparation described by Lovett-Janison and Nelson. The latter contained 0.15 per cent copper. 3. The oxidase activity is proportional to the copper content and the proportionality factor is the same as that reported by Lovett-Janison and Nelson. 4. When dialyzed free of salt, the blue concentrated oxidase solutions precipitate a dark green-blue protein which carries the activity. This may be prevented by keeping the concentrated solutions about 0.1 M in Na2HPO4. 5. When highly diluted for activity measurements the oxidase rapidly loses activity (irreversibly) previous to the measurement, unless the dilution is made with a dilute inert protein (gelatin) solution. Therefore activity values obtained using such gelatin-stabilized dilute solutions of the oxidase run considerably higher than values obtained by the Lovett-Janison and Nelson technique. 6. The effect of pH and substrate concentration on the activity of the purified oxidase in the presence and absence of inert protein was studied. PMID:19873382

  8. Exploring Regulation Genes Involved in the Expression of L-Amino Acid Oxidase in Pseudoalteromonas sp. Rf-1

    PubMed Central

    Wang, Ju; Lin, Jianxun; Zhao, Minyan

    2015-01-01

    Bacterial L-amino acid oxidase (LAAO) is believed to play important biological and ecological roles in marine niches, thus attracting increasing attention to understand the regulation mechanisms underlying its production. In this study, we investigated genes involved in LAAO production in marine bacterium Pseudoalteromonas sp. Rf-1 using transposon mutagenesis. Of more than 4,000 mutants screened, 15 mutants showed significant changes in LAAO activity. Desired transposon insertion was confirmed in 12 mutants, in which disrupted genes and corresponding functionswere identified. Analysis of LAAO activity and lao gene expression revealed that GntR family transcriptional regulator, methylase, non-ribosomal peptide synthetase, TonB-dependent heme-receptor family, Na+/H+ antiporter and related arsenite permease, N-acetyltransferase GCN5, Ketol-acid reductoisomerase and SAM-dependent methytransferase, and their coding genes may be involved in either upregulation or downregulation pathway at transcriptional, posttranscriptional, translational and/or posttranslational level. The nhaD and sdmT genes were separately complemented into the corresponding mutants with abolished LAAO-activity. The complementation of either gene can restore LAAO activity and lao gene expression, demonstrating their regulatory role in LAAO biosynthesis. This study provides, for the first time, insights into the molecular mechanisms regulating LAAO production in Pseudoalteromonas sp. Rf-1, which is important to better understand biological and ecological roles of LAAO. PMID:25815733

  9. Covalent immobilization of ascorbate oxidase onto polycarbonate strip for L-ascorbic acid detection.

    PubMed

    Kannoujia, Dileep Kumar; Kumar, Saroj; Nahar, Pradip

    2012-10-01

    Herein, a simple and rapid method is described for detection of L-ascorbic acid by ascorbate oxidase immobilized onto polycarbonate strip pre-activated by 1-fluoro-2-nitro-4-azidobenzene in photochemical reaction. Covalent attachment of ascorbate oxidase was confirmed by XPS studies. The immobilized-ascorbate oxidase shows higher pH, thermal and storage stability in comparison to free enzyme.

  10. Expression of Ascorbic Acid Oxidase in Zucchini Squash (Cucurbita pepo L.) 1

    PubMed Central

    Lin, Liang-Shiou; Varner, Joseph E.

    1991-01-01

    The expression of ascorbic acid oxidase was studied in zucchini squash (Cucurbita pepo L.), one of the most abundant natural sources of the enzyme. In the developing fruit, specific activity of ascorbic acid oxidase was highest between 4 and 6 days after anthesis. Protein and mRNA levels followed the same trend as enzyme activity. Highest growth rate of the fruit occurred before 6 days after anthesis. Within a given fruit, ascorbic acid oxidase activity and mRNA level were highest in the epidermis, and lowest in the central placental region. In leaf tissue, ascorbic acid oxidase activity was higher in young leaves, and very low in old leaves. Within a given leaf, enzyme activity was highest in the fast-growing region (approximately the lower third of the blade), and lowest in the slow-growing region (near leaf apex). High expression of ascorbic acid oxidase at a stage when rapid growth is occurring (in both fruits and leaves), and localization of the enzyme in the fruit epidermis, where cells are under greatest tension during rapid growth in girth, suggest that ascorbic acid oxidase might be involved in reorganization of the cell wall to allow for expansion. Based on the known chemistry of dehydroascorbic acid, the end product of the ascorbic acid oxidase-catalyzed reaction, we have proposed several hypotheses to explain how dehydroascorbic acid might cause cell wall “loosening.” ImagesFigure 3Figure 4Figure 5 PMID:16668145

  11. Purification and partial characterization of an L-amino acid oxidase from bushmaster snake (Surucucu Pico de Jaca) Lachesis muta muta venom.

    PubMed

    Sánchez, E O; Magalhães, A

    1991-01-01

    1. L-amino acid oxidase (L-AO) from the venom of Lachesis muta muta was purified 72 times (38%) by gel filtration on Sephadex G-100, followed by ion exchange chromatography on DEAE-cellulose and gel filtration on Sephacryl S-300. 2. The protein was shown to be homogeneous by polyacrylamide gel electrophoresis at pH 8.5, immunoelectrophoresis, immunodiffusion and isoelectric focusing. Its specific activity was 44.4 units/mg protein, using 7.5 mM L-leucine as substrate and O-dianisidine as electron donor, at pH 7.6 and 25 degrees C. The increase in absorbance at 436 nm was recorded. 3. The enzyme was characterized as a glycoprotein with an S20,w = 6.72, MW = 138,000 and pI = 5.2. It presented maxima at 389 and 460 nm and contained 2 mol of FAD per mole protein.

  12. Deletion of glucose oxidase changes the pattern of organic acid production in Aspergillus carbonarius

    PubMed Central

    2014-01-01

    Aspergillus carbonarius has potential as a cell factory for the production of different organic acids. At pH 5.5, A.carbonarius accumulates high amounts of gluconic acid when it grows on glucose based medium whereas at low pH, it produces citric acid. The conversion of glucose to gluconic acid is carried out by secretion of the enzyme, glucose oxidase. In this work, the gene encoding glucose oxidase was identified and deleted from A. carbonarius with the aim of changing the carbon flux towards other organic acids. The effect of genetic engineering was examined by testing glucose oxidase deficient (Δgox) mutants for the production of different organic acids in a defined production medium. The results obtained showed that the gluconic acid accumulation was completely inhibited and increased amounts of citric acid, oxalic acid and malic acid were observed in the Δgox mutants. PMID:25401063

  13. Involvement of phospholipase D and NADPH-oxidase in salicylic acid signaling cascade.

    PubMed

    Kalachova, Tetiana; Iakovenko, Oksana; Kretinin, Sergii; Kravets, Volodymyr

    2013-05-01

    Salicylic acid is associated with the primary defense responses to biotic stress and formation of systemic acquired resistance. However, molecular mechanisms of early cell reactions to phytohormone application are currently undisclosed. The present study investigates the participation of phospholipase D and NADPH-oxidase in salicylic acid signal transduction cascade. The activation of lipid signaling enzymes within 15 min of salicylic acid application was shown in Arabidopsis thaliana plants by measuring the phosphatidic acid accumulation. Adding of primary alcohol (1-butanol) to the incubation medium led to phosphatidylbutanol accumulation as a result of phospholipase D (PLD) action in wild-type and NADPH-oxidase RbohD deficient plants. Salicylic acid induced rapid increase in NADPH-oxidase activity in histochemical assay with nitroblue tetrazolium but the reaction was not observed in presence of 1-butanol and NADPH-oxidase inhibitor diphenylene iodide (DPI). The further physiological effect of salicylic acid and inhibitory analysis of the signaling cascade were made in the guard cell model. Stomatal closure induced by salicylic acid was inhibited by 1-butanol and DPI treatment. rbohD transgenic plants showed impaired stomatal reaction upon phytohormone effect, while the reaction to H2O2 did not differ from that of wild-type plants. Thus a key role of NADPH-oxidase D-isoform in the process of stomatal closure in response to salicylic acid has been postulated. It has enabled to predict a cascade implication of PLD and NADPH oxidase to salicylic acid signaling pathway.

  14. D-amino acid oxidase: its potential in the production of 7-aminocephalosporanic acid.

    PubMed

    Mujawar, S K

    1999-01-01

    D-Amino acid oxidase (DAAO) used in the preparation of alpha-keto acids, in the determination of D-amino acids and in the resolution of racemic mixture of amino acids is produced by a wide range of microorganisms. In the recent past this enzyme is being recognized for its potential in the commercial production of 7-aminocephalosporanic acid (7-ACA), a starting material for various semisynthetic cephalosporins. Though this enzyme is widespread among microorganisms, very few microbial species have been explored for the production of 7-ACA; this is because cephalosporin C is quantitatively deaminated by limited microbial DAAOs. Comparison of physico-chemical properties of enzyme preparations indicate wide variations, however in general DAAOs are specific for D-configuration of amino acids. Both immobilized enzyme and cell preparations are developed for its various applications. The advantages of DAAO in the production of 7-ACA are discussed.

  15. Expression of ascorbic acid oxidase in zucchini squash (Cucurbita pepo L. )

    SciTech Connect

    Lin, Liangshiou; Varner, J.E. )

    1991-05-01

    The expression of ascorbic acid oxidase was studied in zuchini squash (Cucurbita pepo L.), one of the most abundant natural sources of the enzyme. In the developing fruit, specific activity of ascorbic acid oxidase was highest between 4 and 6 days after anthesis. Protein and mRNA levels followed the same trend as enzyme activity. Highest growth rate of the fruit occurred before 6 days after anthesis. Within a given fruit, ascorbic acid oxidase activity was higher in young leaves, and very low in old leaves. Within a given leaf, enzyme activity was highest in the fast-growing region (approximately the lower third of the blade), and lowest in the central placental region. In leaf tissue, ascorbic acid oxidase activity was higher in young leaves, and very low in old leaves. Within a given leaf, enzyme activity was highest in the fast-growing region (approximately the lower third of the blade), and lowest in the slow-growing region (near leaf apex). High expression of ascorbic acid oxidase at a stage when rapid growth is occurring (in both fruits and leaves), and localization of the enzyme in the fruit epidermis, where cells are under greatest tension during rapid growth in girth, suggest that ascorbic acid oxidase might be involved in reorganization of the cell wall to allow for expansion. Based on the known chemistry of dehydroascorbic acid, the end product of the ascorbic acid oxidase-catalyzed reaction, the authors have proposed several hypotheses to explain how dehydroascorbic acid might cause cell wall loosening.

  16. Induction of the d-Amino Acid Oxidase from Trigonopsis variabilis

    PubMed Central

    Horner, R.; Wagner, F.; Fischer, L.

    1996-01-01

    Induction of the d-amino acid oxidase (EC. 1.4.3.3) from the yeast Trigonopsis variabilis was investigated by using a minimal medium containing glucose as the carbon and energy source, (NH(inf4))(inf2)SO(inf4) as the nitrogen source, and various d- and dl-amino acid derivatives as inducers. The best new inducers found were N-carbamoyl-d-alanine, N-acetyl-d-tryptophan, and N-chloroacetyl-d-(alpha)-aminobutyric acid; when the induction effects of these compounds were compared with the effects of d-alanine as the nitrogen source and inducer, the resulting activities of d-amino acid oxidase per gram of dried yeast were 4.2, 2.1, and 1.5 times higher, respectively. The optimum concentration of the best inducer, N-carbamoyl-d-alanine, was 5 mM. This inducer could also be used in its racemic form. The induction was pH dependent. After cultivation of the yeast in a 50-liter bioreactor, d-amino acid oxidase activity of about 3,850 (mu)kat (231,000 U) was obtained. In addition, production of the d-amino acid oxidase was found to be significantly dependent on the metal salt composition of the medium. Addition of zinc ions was required to obtain high d-amino acid oxidase levels in the cells. The optimum concentration of ZnSO(inf4) was about 140 (mu)M. PMID:16535339

  17. Snake Venom L-Amino Acid Oxidases: Trends in Pharmacology and Biochemistry

    PubMed Central

    Izidoro, Luiz Fernando M.; Sobrinho, Juliana C.; Mendes, Mirian M.; Costa, Tássia R.; Grabner, Amy N.; Rodrigues, Veridiana M.; da Silva, Saulo L.; Zanchi, Fernando B.; Zuliani, Juliana P.; Fernandes, Carla F. C.; Calderon, Leonardo A.; Stábeli, Rodrigo G.; Soares, Andreimar M.

    2014-01-01

    L-amino acid oxidases are enzymes found in several organisms, including venoms of snakes, where they contribute to the toxicity of ophidian envenomation. Their toxicity is primarily due to enzymatic activity, but other mechanisms have been proposed recently which require further investigation. L-amino acid oxidases exert biological and pharmacological effects, including actions on platelet aggregation and the induction of apoptosis, hemorrhage, and cytotoxicity. These proteins present a high biotechnological potential for the development of antimicrobial, antitumor, and antiprotozoan agents. This review provides an overview of the biochemical properties and pharmacological effects of snake venom L-amino acid oxidases, their structure/activity relationship, and supposed mechanisms of action described so far. PMID:24738050

  18. Time dependent inhibition of xanthine oxidase in irradiated solutions of folic acid, aminopterin and methotrexate

    SciTech Connect

    Robinson, K.; Pilot, T.F.; Meany, J.E. )

    1990-01-01

    The xanthine oxidase catalyzed oxidation of hypoxanthine was followed by monitoring the formation of uric acid at 290 nm. Inhibition of xanthine oxidase occurs in aqueous solutions of folic acid methotrexate and aminopterin. These compounds are known to dissociate upon exposure to ultraviolet light resulting in the formation of their respective 6-formylpteridine derivatives. The relative rates of dissociation were monitored spectrophotometrically by determining the absorbance of their 2,4-dinitrophenylhydrazine derivatives at 500 nm. When aqueous solutions of folic acid, aminopterin and methotrexate were exposed to uv light, a direct correlation was observed between the concentrations of the 6-formylpteridine derivatives existing in solution and the ability of these solutions to inhibit xanthine oxidase. The relative potency of the respective photolysis products were estimated.

  19. Snake venom L-amino acid oxidases: trends in pharmacology and biochemistry.

    PubMed

    Izidoro, Luiz Fernando M; Sobrinho, Juliana C; Mendes, Mirian M; Costa, Tássia R; Grabner, Amy N; Rodrigues, Veridiana M; da Silva, Saulo L; Zanchi, Fernando B; Zuliani, Juliana P; Fernandes, Carla F C; Calderon, Leonardo A; Stábeli, Rodrigo G; Soares, Andreimar M

    2014-01-01

    L-amino acid oxidases are enzymes found in several organisms, including venoms of snakes, where they contribute to the toxicity of ophidian envenomation. Their toxicity is primarily due to enzymatic activity, but other mechanisms have been proposed recently which require further investigation. L-amino acid oxidases exert biological and pharmacological effects, including actions on platelet aggregation and the induction of apoptosis, hemorrhage, and cytotoxicity. These proteins present a high biotechnological potential for the development of antimicrobial, antitumor, and antiprotozoan agents. This review provides an overview of the biochemical properties and pharmacological effects of snake venom L-amino acid oxidases, their structure/activity relationship, and supposed mechanisms of action described so far.

  20. L-Amino acid oxidases from microbial sources: types, properties, functions, and applications.

    PubMed

    Hossain, Gazi Sakir; Li, Jianghua; Shin, Hyun-dong; Du, Guocheng; Liu, Long; Chen, Jian

    2014-02-01

    L-Amino acid oxidases (LAAOs), which catalyze the stereospecific oxidative deamination of L-amino acids to α-keto acids and ammonia, are flavin adenine dinucleotide-containing homodimeric proteins. L-Amino acid oxidases are widely distributed in diverse organisms and have a range of properties. Because expressing LAAOs as recombinant proteins in heterologous hosts is difficult, their biotechnological applications have not been thoroughly advanced. LAAOs are thought to contribute to amino acid catabolism, enhance iron acquisition, display antimicrobial activity, and catalyze keto acid production, among other roles. Here, we review the types, properties, structures, biological functions, heterologous expression, and applications of LAAOs obtained from microbial sources. We expect this review to increase interest in LAAO studies.

  1. Early Effects of Boron Deficiency on Indoleacetic Acid Oxidase Levels of Squash Root Tips

    PubMed Central

    Bohnsack, Charles W.; Albert, Luke S.

    1977-01-01

    The indoleacetic acid (IAA) oxidase activity of root tips of boron-sufficient, -deficient, recovering, and IAA-treated boron-sufficient squash plants (Cucurbita pepo L.) was determined. Apical and subapical root sections displayed an increase in IAA oxidase activity between 6 and 9 hours after boron was withheld, and after 24 hours the activity of the apical sections showed a 20-fold increase over +B controls. Root elongation of -B plants was inhibited before an increase in oxidase activity could be detected. Roots of plants subjected to 12 hours of -B treatment and then transferred to +B treatment for recovery regained normal elongation rates and oxidase activity within 18 to 20 hours. IAA treatment of +B plants increased IAA oxidase activity of apical and subapical root sections and also inhibited root elongation and caused symptoms similar to -B treatments. These results have demonstrated the earliest enzymic change for intact boron-deficient plants. The results are in agreement with the theory that boron deficiency symptoms may be the result of supraoptimal endogenous levels of IAA. These high levels of IAA may inhibit cell division and lead to an induction of the IAA oxidase enzyme. PMID:16659990

  2. Effect of high pressure on peanut allergens in the presence of polyphenol oxidase and caffeic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High pressure (HP) enhances enzymatic reactions. Because polyphenol oxidase (PPO) is an enzyme, and reduces IgE binding of peanut allergens in presence of caffeic acid (CA), we postulated that a further reduction in IgE binding can be achieved, using HP together with PPO and CA. Peanut extracts cont...

  3. High-level expression of Rhodotorula gracilis D-amino acid oxidase in Pichia pastoris.

    PubMed

    Abad, Sandra; Nahalka, Jozef; Winkler, Margit; Bergler, Gabriele; Speight, Robert; Glieder, Anton; Nidetzky, Bernd

    2011-03-01

    By combining gene design and heterologous over-expression of Rhodotorula gracilis D-amino acid oxidase (RgDAO) in Pichia pastoris, enzyme production was enhanced by one order of magnitude compared to literature benchmarks, giving 350 kUnits/l of fed-batch bioreactor culture with a productivity of 3.1 kUnits/l h. P. pastoris cells permeabilized by freeze-drying and incubation in 2-propanol (10% v/v) produce a highly active (1.6 kUnits/g dry matter) and stable oxidase preparation. Critical bottlenecks in the development of an RgDAO catalyst for industrial applications have been eliminated.

  4. D-Amino acid oxidase and presence of D-proline in Xenopus laevis.

    PubMed

    Soma, Hiroki; Furuya, Ryuji; Kaneko, Ryo; Tsukamoto, Ayaka; Shirasu, Kazumitsu; Tanigawa, Minoru; Nagata, Yoko

    2013-10-01

    We purified D-amino acid oxidase (EC 1.4.3.3, DAO) from Xenopus laevis tadpoles. The optimal temperature and pH for enzyme activity were 35-40 °C and 8.3-9.0, respectively, depending on the substrate amino acids available to the enzyme; the highest activity was observed with D-proline followed by D-phenylalanine. Activity was significantly inhibited by p-hydroxymercuribenzoate, but only moderately by p-chloromercuribenzoate or benzoate. Enzyme activity was increased until the final tadpole stage, but was reduced to one-third in the adult and was localized primarily in the kidney. The tadpoles contained high concentrations of D-proline close to the final developmental stage and nearly no D-amino acids were detected in the adult frog, indicating that D-amino acid oxidase functions in metamorphosis.

  5. Electrochemical L-lactic acid sensor based on immobilized ZnO nanorods with lactate oxidase.

    PubMed

    Ibupoto, Zafar Hussain; Shah, Syed Muhammad Usman Ali; Khun, Kimleang; Willander, Magnus

    2012-01-01

    In this work, fabrication of gold coated glass substrate, growth of ZnO nanorods and potentiometric response of lactic acid are explained. The biosensor was developed by immobilizing the lactate oxidase on the ZnO nanorods in combination with glutaraldehyde as a cross linker for lactate oxidase enzyme. The potentiometric technique was applied for the measuring the output (EMF) response of l-lactic acid biosensor. We noticed that the present biosensor has wide linear detection range of concentration from 1 × 10(-4)-1 × 10(0) mM with acceptable sensitivity about 41.33 ± 1.58 mV/decade. In addition, the proposed biosensor showed fast response time less than 10 s, a good selectivity towards l-lactic acid in presence of common interfering substances such as ascorbic acid, urea, glucose, galactose, magnesium ions and calcium ions. The present biosensor based on immobilized ZnO nanorods with lactate oxidase sustained its stability for more than three weeks.

  6. Endoplasmic Reticulum Thiol Oxidase Deficiency Leads to Ascorbic Acid Depletion and Noncanonical Scurvy in Mice

    PubMed Central

    Zito, Ester; Hansen, Henning Gram; Yeo, Giles S.H.; Fujii, Junichi; Ron, David

    2012-01-01

    Summary Endoplasmic reticulum (ER) thiol oxidases initiate a disulfide relay to oxidatively fold secreted proteins. We found that combined loss-of-function mutations in genes encoding the ER thiol oxidases ERO1α, ERO1β, and PRDX4 compromised the extracellular matrix in mice and interfered with the intracellular maturation of procollagen. These severe abnormalities were associated with an unexpectedly modest delay in disulfide bond formation in secreted proteins but a profound, 5-fold lower procollagen 4-hydroxyproline content and enhanced cysteinyl sulfenic acid modification of ER proteins. Tissue ascorbic acid content was lower in mutant mice, and ascorbic acid supplementation improved procollagen maturation and lowered sulfenic acid content in vivo. In vitro, the presence of a sulfenic acid donor accelerated the oxidative inactivation of ascorbate by an H2O2-generating system. Compromised ER disulfide relay thus exposes protein thiols to competing oxidation to sulfenic acid, resulting in depletion of ascorbic acid, impaired procollagen proline 4-hydroxylation, and a noncanonical form of scurvy. PMID:22981861

  7. Endoplasmic reticulum thiol oxidase deficiency leads to ascorbic acid depletion and noncanonical scurvy in mice.

    PubMed

    Zito, Ester; Hansen, Henning Gram; Yeo, Giles S H; Fujii, Junichi; Ron, David

    2012-10-12

    Endoplasmic reticulum (ER) thiol oxidases initiate a disulfide relay to oxidatively fold secreted proteins. We found that combined loss-of-function mutations in genes encoding the ER thiol oxidases ERO1α, ERO1β, and PRDX4 compromised the extracellular matrix in mice and interfered with the intracellular maturation of procollagen. These severe abnormalities were associated with an unexpectedly modest delay in disulfide bond formation in secreted proteins but a profound, 5-fold lower procollagen 4-hydroxyproline content and enhanced cysteinyl sulfenic acid modification of ER proteins. Tissue ascorbic acid content was lower in mutant mice, and ascorbic acid supplementation improved procollagen maturation and lowered sulfenic acid content in vivo. In vitro, the presence of a sulfenic acid donor accelerated the oxidative inactivation of ascorbate by an H(2)O(2)-generating system. Compromised ER disulfide relay thus exposes protein thiols to competing oxidation to sulfenic acid, resulting in depletion of ascorbic acid, impaired procollagen proline 4-hydroxylation, and a noncanonical form of scurvy.

  8. Kinetics of Inhibition of Monoamine Oxidase Using Curcumin and Ellagic Acid

    PubMed Central

    Khatri, Dharmendra Kumar; Juvekar, Archana Ramesh

    2016-01-01

    Background: Curcumin and ellagic are the natural polyphenols having a wide range of pharmacological actions. They have been reported to have their use in various neurological disorders. Objective: This study was aimed to evaluate the effect of curcumin and ellagic acid on the activity of monoamine oxidase (MAO), the enzyme responsible for metabolism of monoamine neurotransmitters which are pivotal for neuronal development and function. Materials and Methods: The in vitro effects of these selected polyphenols on MAO activities in mitochondria isolated from rat brains were examined. Brain mitochondria were assayed for MAO type-B (MAO-B) using benzylamine as substrates. Rat brain mitochondrial MAO preparation was used to study the kinetics of enzyme inhibition using double reciprocal Lineweaver–Burk plot. Results: MAO activity was inhibited by curcumin and ellagic acid; however, higher half maximal inhibitory concentrations of curcumin (500.46 nM) and ellagic acid (412.24 nM) were required compared to the known MAO-B inhibitor selegiline. It is observed that the curcumin and ellagic acid inhibit the MAO activity with both the competitive and noncompetitive type of inhibitions. Conclusions: Curcumin and ellagic acid can be considered a possible source of MAO inhibitor used in the treatment of Parkinson's and other neurological disorders. SUMMARY Monoamine oxidase (MAO) is involved in a variety of neurological disorders including Parkinson's disease (PD)Curcumin and ellagic acid inhibit the monoamine oxidase activityEllagic acid revealed more potent MAO type-B (MAO-B) inhibitory activity than curcuminKinetic studies of MAO inhibition using different concentrations of curcumin and ellagic acid were plotted as double reciprocal Lineweaver–Burk plotThe mode of inhibition of both compounds toward MAO-B is mixed (competitive and uncompetitive) type of inhibition with both the competitive and noncompetitive type of inhibitions. Abbreviations used: MAO: Monoamine oxidase

  9. Evidence for the involvement of GPR40 and NADPH oxidase in palmitic acid-induced superoxide production and insulin secretion.

    PubMed

    Graciano, Maria Fernanda; Valle, Maíra Mello; Curi, Rui; Carpinelli, Angelo Rafael

    2013-01-01

    G protein coupled receptor 40 (GPR40) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex have been shown to be involved in the fatty acid amplification of glucose-stimulated insulin secretion (GSIS). The effect of palmitic acid on superoxide production and insulin secretion by INS-1E cells and the possible involvement of GPR40 and NADPH oxidase in these processes were examined in this study. Cells were incubated during 1 h with palmitic acid in low and high glucose concentrations, a GPR40 agonist (GW9508) and inhibitors of NADPH oxidase (diphenyleneiodonium, DPI) and PKC (calphostin C). GW9508 induced superoxide production at 2.8 and 5.6 mM glucose concentrations and stimulated insulin secretion at 16.7 mM glucose concentration involving both PKC and NADPH oxidase activation. Palmitic acid induced superoxide production through NADPH oxidase and GPR40-dependent pathways and the stimulation of insulin secretion in the presence of a high glucose concentration was reduced by knockdown of GPR40 using siRNA. Our results suggest that palmitic acid induces superoxide production and potentiates GSIS through NADPH oxidase and GPR40 pathways in pancreatic ? cells.

  10. A Highly Stable d-Amino Acid Oxidase of the Thermophilic Bacterium Rubrobacter xylanophilus

    PubMed Central

    Furukawara, Makoto; Omae, Keishi; Tadokoro, Namiho; Saito, Yayoi; Abe, Katsumasa; Kera, Yoshio

    2014-01-01

    d-Amino acid oxidase (DAO) is a biotechnologically attractive enzyme that can be used in a variety of applications, but its utility is limited by its relatively poor stability. A search of a bacterial genome database revealed a gene encoding a protein homologous to DAO in the thermophilic bacterium Rubrobacter xylanophilus (RxDAO). The recombinant protein expressed in Escherichia coli was a monomeric protein containing noncovalently bound flavin adenine dinucleotide as a cofactor. This protein exhibited oxidase activity against neutral and basic d-amino acids and was significantly inhibited by a DAO inhibitor, benzoate, but not by any of the tested d-aspartate oxidase (DDO) inhibitors, thus indicating that the protein is DAO. RxDAO exhibited higher activities and affinities toward branched-chain d-amino acids, with the highest specific activity toward d-valine and catalytic efficiency (kcat/Km) toward d-leucine. Substrate inhibition was observed in the case of d-tyrosine. The enzyme had an optimum pH range and temperature of pH 7.5 to 10 and 65°C, respectively, and was stable between pH 5.0 and pH 8.0, with a T50 (the temperature at which 50% of the initial enzymatic activity is lost) of 64°C. No loss of enzyme activity was observed after a 1-week incubation period at 30°C. This enzyme was markedly inactivated by phenylmethylsulfonyl fluoride but not by thiol-modifying reagents and diethyl pyrocarbonate, which are known to inhibit certain DAOs. These results demonstrated that RxDAO is a highly stable DAO and suggested that this enzyme may be valuable for practical applications, such as the determination and quantification of branched-chain d-amino acids, and as a scaffold to generate a novel DAO via protein engineering. PMID:25217016

  11. In Situ Click Chemistry for the Identification of a Potent D-Amino Acid Oxidase Inhibitor.

    PubMed

    Toguchi, Shohei; Hirose, Tomoyasu; Yorita, Kazuko; Fukui, Kiyoshi; Sharpless, K Barry; Ōmura, Satoshi; Sunazuka, Toshiaki

    2016-07-01

    In situ click chemistry is a target-guided synthesis approach for discovering novel lead compounds by assembling organic azides and alkynes into triazoles inside the affinity site of target biogenic molecules such as proteins. We report in situ click chemistry screening with human D-amino acid oxidase (hDAO), which led to the identification of a more potent hDAO inhibitor. The hDAO inhibitors have chemotherapeutic potential as antipsychotic agents. The new inhibitor displayed competitive inhibition of hDAO and showed significantly increased inhibitory activity against hDAO compared with that of an anchor molecule of in situ click chemistry.

  12. A novel D-amino acid oxidase from a contaminated agricultural soil metagenome and its characterization.

    PubMed

    Ou, Qian; Liu, Yao; Deng, Jie; Chen, Gao; Yang, Ying; Shen, Peihong; Wu, Bo; Jiang, Chengjian

    2015-06-01

    A novel D-amino acid oxidase (DAAO) gene designated as daoE was cloned by the sequence-based screening of a plasmid metagenomic library of uncultured microorganisms from contaminated agricultural soil. The deduced amino acid sequence comparison and phylogenetic analysis indicated that daoE and other putative DAAOs are closely related. The putative DAAO gene was subcloned into a pETBlue-2 vector and overexpressed in Escherichia coli Tunner(DE3)pLacI. The recombinant protein was purified to homogeneity. The maximum activity of DaoE protein occurred at pH 8.0 and 37 °C. DaoE recombinant protein had an apparent K m of 2.96 mM, V max of 0.018 mM/min, k cat of 10.9/min, and k cat/K m of 1.16 × 10(4)/mol/min. The identification of this novel DAAO gene demonstrated the importance of metagenomic libraries in exploring new D-amino acid oxidases from environmental microorganisms to optimize their applications.

  13. Ascorbate Oxidase-Based Amperometric Biosensor for l-Ascorbic Acid Determination in Beverages.

    PubMed

    Csiffáry, Gábor; Fűtő, Péter; Adányi, Nóra; Kiss, Attila

    2016-03-01

    A novel biosensor for l-ascorbic acid determination in different beverages was elaborated. The ascorbate oxidase enzyme (AAO) from Cucurbita sp., EC 1.10.3.3, was immobilized on a screen-printed carbon electrode with poly(ethylene glycol) (400) diglycidyl ether (PEGDGE) as a crosslinking agent. The standards and samples were measured first with a blank electrode. An inert protein, bovine serum albumin (BSA), was immobilized on the surface of this electrode with PEGDGE. The BSA mass was equivalent to the mass of 10 U of AAO enzyme immobilized on the electrodes (0.021 mg). The linear measuring range for l-ascorbic acid was between 5 and 150 µmol/L. As l-ascorbic acid is a vital vitamin and a common antioxidant used in food industry, fruit juices and vitamin C effervescent tablets were examined. The results were compared to HPLC measurements.

  14. Crystal structure and molecular dynamics studies of L-amino acid oxidase from Bothrops atrox.

    PubMed

    Feliciano, Patricia R; Rustiguel, Joane K; Soares, Ricardo O S; Sampaio, Suely V; Cristina Nonato, M

    2017-03-15

    L-amino acid oxidases (LAAOs) are dimeric flavoproteins that catalyze the deamination of L-amino acid to α-keto acid, producing ammonia and hydrogen peroxide. In this study, we report the crystal structure and molecular dynamics simulations of LAAO from the venom of Bothrops atrox (BatroxLAAO). BatroxLAAO presents several biological and pharmacological properties with promising biomedical applications. BatroxLAAO structure contains the highly conserved structural pattern of LAAOs comprising a FAD-binding domain, substrate-binding domain and helical domain, and a dimeric arrangement that can be stabilized by zinc. Also, molecular dynamics results show an asymmetric behavior, and a direct communication between FAD- and substrate-binding domains of counterpart subunits. These findings shed light on the structural role of dimerization to catalytic mechanism of SV-LAAOs.

  15. Ascorbate Oxidase-Based Amperometric Biosensor for l-Ascorbic Acid Determination in Beverages

    PubMed Central

    Csiffáry, Gábor; Fűtő, Péter; Adányi, Nóra; Kiss, Attila

    2016-01-01

    Summary A novel biosensor for l-ascorbic acid determination in different beverages was elaborated. The ascorbate oxidase enzyme (AAO) from Cucurbita sp., EC 1.10.3.3, was immobilized on a screen-printed carbon electrode with poly(ethylene glycol) (400) diglycidyl ether (PEGDGE) as a crosslinking agent. The standards and samples were measured first with a blank electrode. An inert protein, bovine serum albumin (BSA), was immobilized on the surface of this electrode with PEGDGE. The BSA mass was equivalent to the mass of 10 U of AAO enzyme immobilized on the electrodes (0.021 mg). The linear measuring range for l-ascorbic acid was between 5 and 150 µmol/L. As l-ascorbic acid is a vital vitamin and a common antioxidant used in food industry, fruit juices and vitamin C effervescent tablets were examined. The results were compared to HPLC measurements. PMID:27904390

  16. Oxalic acid degradation by a novel fungal oxalate oxidase from Abortiporus biennis.

    PubMed

    Grąz, Marcin; Rachwał, Kamila; Zan, Radosław; Jarosz-Wilkołazka, Anna

    2016-01-01

    Oxalate oxidase was identified in mycelial extracts of a basidiomycete Abortiporus biennis strain. Intracellular enzyme activity was detected only after prior lowering of the pH value of the fungal cultures by using oxalic or hydrochloric acids. This enzyme was purified using size exclusion chromatography (Sephadex G-25) and ion-exchange chromatography (DEAE-Sepharose). This enzyme exhibited optimum activity at pH 2 when incubated at 40°C, and the optimum temperature was established at 60°C. Among the tested organic acids, this enzyme exhibited specificity only towards oxalic acid. Molecular mass was calculated as 58 kDa. The values of Km for oxalate and Vmax for the enzyme reaction were 0.015 M and 30 mmol min(-1), respectively.

  17. In vitro and in vivo studies on adlay-derived seed extracts: phenolic profiles, antioxidant activities, serum uric acid suppression, and xanthine oxidase inhibitory effects.

    PubMed

    Zhao, Mouming; Zhu, Dashuai; Sun-Waterhouse, Dongxiao; Su, Guowan; Lin, Lianzhu; Wang, Xiao; Dong, Yi

    2014-08-06

    This study aimed to explore the potential of polished adlay, brown adlay, adlay bran, and adlay hull to prevent and treat hyperuricemia. Brown adlay extract effectively decreased the serum uric acid levels of oxonate-induced hyperuricemic rats. Free and bound phenolic extracts from these materials contained significant amounts of phenolics, with free phenolics dominated by chlorogenic acid and p-coumaric acid while bound phenolics dominated by p-coumaric acid and ferulic acid. Free and bound phenolics of adlay bran exhibited significant xanthine oxidase inhibition activities, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities, oxygen radical absorbance capacities, and superoxide radical scavenging activities. Adlay bran phenolics could be effective xanthine oxidase inhibitors and radical scavengers. p-Coumaric acid is a xanthine oxidase inhibitor with strong superoxide radical scavenging activity. However, ferulic acid is a xanthine oxidase inhibitor with weak superoxide radical scavenging activity. Chlorogenic acid is a superoxide radical scavenger with weak xanthine oxidase inhibitory activity.

  18. Use of Glucose Oxidase in a Membrane Reactor for Gluconic Acid Production

    NASA Astrophysics Data System (ADS)

    Das Neves, Luiz Carlos Martins; Vitolo, Michele

    This article aims at the evaluation of the catalytic performance of glucose oxidase (GO) (EC.1.1.3.4) for the glucose/gluconic acid conversion in the ultrafiltration cell type membrane reactor (MB-CSTR). The reactor was coupled with a Millipore ultrafiltration-membrane (cutoff of 100 kDa) and operated for 24 h under agitation of 100 rpm, pH 5.5, and 30°C. The experimental conditions varied were the glucose concentration (2.5, 5.0, 10.0, 20.0, and 40.0 mM), the feeding rate (0.5, 1.0, 3.0, and 6.0/h), dissolved oxygen (8.0 and 16.0 mg/L), GO concentration (2.5, 5.0, 10.0, and 20.0 UGO/mL), and the glucose oxidase/catalase activity ratio (UGO/UCAT)(1∶0, 1∶10, 1∶20, and 1∶30). A conversion yield of 80% and specific reaction rate of 40×10-4 mmol/h·UGO were attained when the process was carried out under the following conditions: D=3.0/h, dissolved oxygen=16.0 mg/L, [G]=40 mM, and (UGO/UCAT)=1∶20. A simplified model for explaining the inhibition of GO activity by hydrogen peroxide, formed during the glucose/gluconic acid conversion, was presented.

  19. Genipin Cross-Linked Glucose Oxidase and Catalase Multi-enzyme for Gluconic Acid Synthesis.

    PubMed

    Cui, Caixia; Chen, Haibin; Chen, Biqiang; Tan, Tianwei

    2017-02-01

    In this work, glucose oxidase (GOD) and catalase (CAT) were used simultaneously to produce gluconic acid from glucose. In order to reduce the distance between the two enzymes, and therefore improve efficiency, GOD and CAT were cross-linked together using genipin. Improvements in gluconic acid production were due to quick removal of harmful intermediate hydrogen peroxide by CAT. GOD activity was significantly affected by the proportion of CAT in the system, with GOD activity in the cross-linked multi-enzyme (CLME) being 10 times higher than that in an un-cross-linked GOD/CAT mixture. The glucose conversion rate after 15 h using 15 % glucose was also 10 % higher using the CLME than was measured using a GOD/CAT mixture.

  20. Plant and animal glycolate oxidases have a common eukaryotic ancestor and convergently duplicated to evolve long-chain 2-hydroxy acid oxidases.

    PubMed

    Esser, Christian; Kuhn, Anke; Groth, Georg; Lercher, Martin J; Maurino, Veronica G

    2014-05-01

    Glycolate oxidase (GOX) is a crucial enzyme of plant photorespiration. The encoding gene is thought to have originated from endosymbiotic gene transfer between the eukaryotic host and the cyanobacterial endosymbiont at the base of plantae. However, animals also possess GOX activities. Plant and animal GOX belong to the gene family of (L)-2-hydroxyacid-oxidases ((L)-2-HAOX). We find that all (L)-2-HAOX proteins in animals and archaeplastida go back to one ancestral eukaryotic sequence; the sole exceptions are green algae of the chlorophyta lineage. Chlorophyta replaced the ancestral eukaryotic (L)-2-HAOX with a bacterial ortholog, a lactate oxidase that may have been obtained through the primary endosymbiosis at the base of plantae; independent losses of this gene may explain its absence in other algal lineages (glaucophyta, rhodophyta, and charophyta). We also show that in addition to GOX, plants possess (L)-2-HAOX proteins with different specificities for medium- and long-chain hydroxyacids (lHAOX), likely involved in fatty acid and protein catabolism. Vertebrates possess lHAOX proteins acting on similar substrates as plant lHAOX; however, the existence of GOX and lHAOX subfamilies in both plants and animals is not due to shared ancestry but is the result of convergent evolution in the two most complex eukaryotic lineages. On the basis of targeting sequences and predicted substrate specificities, we conclude that the biological role of plantae (L)-2-HAOX in photorespiration evolved by co-opting an existing peroxisomal protein.

  1. [Enzymatic production of α-ketoglutaric acid by L-glutamate oxidase from L-glutamic acid].

    PubMed

    Niu, Panqing; Zhang, Zhenyu; Liu, Liming

    2014-08-01

    We produced α-ketoglutaric acid (α-KG) from L-glutamic acid, using enzymatic transformation approach with L-glutamate oxidase (LGOX). First, wild strain Streptomyces sp. FMME066 was mutated with NTG, a genetically stable mutant Streptomyces sp. FMME067 was obtained. Under the optimal nutrition conditions with fructose 10 g/L, peptone 7.5 g/L, KH2PO4 1 g/L and CaCl2 0.05 g/L, the maximum LGOX activity reached 0.14 U/mL. The LGOX was stable to pH and temperature, and Mn2+ had a stimulating effect. Finally, after 24 h enzymatic conversion under the optimal conditions, the maximum titer of α-KG reached 38.1 g/L from 47 g/L L-glutamic acid. Enzymatic transformation by LGOX is a potential approach for α-KG production.

  2. Discovery of pyrazole carboxylic acids as potent inhibitors of rat long chain L-2-hydroxy acid oxidase.

    PubMed

    Barawkar, Dinesh A; Bandyopadhyay, Anish; Deshpande, Anil; Koul, Summon; Kandalkar, Sachin; Patil, Pradeep; Khose, Goraksha; Vyas, Samir; Mone, Mahesh; Bhosale, Shubhangi; Singh, Umesh; De, Siddhartha; Meru, Ashwin; Gundu, Jayasagar; Chugh, Anita; Palle, Venkata P; Mookhtiar, Kasim A; Vacca, Joseph P; Chakravarty, Prasun K; Nargund, Ravi P; Wright, Samuel D; Roy, Sophie; Graziano, Michael P; Cully, Doris; Cai, Tian-Quan; Singh, Sheo B

    2012-07-01

    Long chain L-2-hydroxy acid oxidase 2 (Hao2) is a peroxisomal enzyme expressed in the kidney and the liver. Hao2 was identified as a candidate gene for blood pressure (BP) quantitative trait locus (QTL) but the identity of its physiological substrate and its role in vivo remains largely unknown. To define a pharmacological role of this gene product, we report the development of selective inhibitors of Hao2. We identified pyrazole carboxylic acid hits 1 and 2 from screening of a compound library. Lead optimization of these hits led to the discovery of 15-XV and 15-XXXII as potent and selective inhibitors of rat Hao2. This report details the structure activity relationship of the pyrazole carboxylic acids as specific inhibitors of Hao2.

  3. Oleic, Linoleic and Linolenic Acids Increase ROS Production by Fibroblasts via NADPH Oxidase Activation

    PubMed Central

    Hatanaka, Elaine; Dermargos, Alexandre; Hirata, Aparecida Emiko; Vinolo, Marco Aurélio Ramirez; Carpinelli, Angelo Rafael; Newsholme, Philip; Armelin, Hugo Aguirre; Curi, Rui

    2013-01-01

    The effect of oleic, linoleic and γ-linolenic acids on ROS production by 3T3 Swiss and Rat 1 fibroblasts was investigated. Using lucigenin-amplified chemiluminescence, a dose-dependent increase in extracellular superoxide levels was observed during the treatment of fibroblasts with oleic, linoleic and γ-linolenic acids. ROS production was dependent on the addition of β-NADH or NADPH to the medium. Diphenyleneiodonium inhibited the effect of oleic, linoleic and γ-linolenic acids on fibroblast superoxide release by 79%, 92% and 82%, respectively. Increased levels of p47phox phosphorylation due to fatty acid treatment were detected by Western blotting analyses of fibroblast proteins. Increased p47phox mRNA expression was observed using real-time PCR. The rank order for the fatty acid stimulation of the fibroblast oxidative burst was as follows: γ-linolenic > linoleic > oleic. In conclusion, oleic, linoleic and γ-linolenic acids stimulated ROS production via activation of the NADPH oxidase enzyme complex in fibroblasts. PMID:23579616

  4. Oleic, linoleic and linolenic acids increase ros production by fibroblasts via NADPH oxidase activation.

    PubMed

    Hatanaka, Elaine; Dermargos, Alexandre; Hirata, Aparecida Emiko; Vinolo, Marco Aurélio Ramirez; Carpinelli, Angelo Rafael; Newsholme, Philip; Armelin, Hugo Aguirre; Curi, Rui

    2013-01-01

    The effect of oleic, linoleic and γ-linolenic acids on ROS production by 3T3 Swiss and Rat 1 fibroblasts was investigated. Using lucigenin-amplified chemiluminescence, a dose-dependent increase in extracellular superoxide levels was observed during the treatment of fibroblasts with oleic, linoleic and γ-linolenic acids. ROS production was dependent on the addition of β-NADH or NADPH to the medium. Diphenyleneiodonium inhibited the effect of oleic, linoleic and γ-linolenic acids on fibroblast superoxide release by 79%, 92% and 82%, respectively. Increased levels of p47 (phox) phosphorylation due to fatty acid treatment were detected by Western blotting analyses of fibroblast proteins. Increased p47 (phox) mRNA expression was observed using real-time PCR. The rank order for the fatty acid stimulation of the fibroblast oxidative burst was as follows: γ-linolenic > linoleic > oleic. In conclusion, oleic, linoleic and γ-linolenic acids stimulated ROS production via activation of the NADPH oxidase enzyme complex in fibroblasts.

  5. Isolation of oxalic acid tolerating fungi and decipherization of its potential to control Sclerotinia sclerotiorum through oxalate oxidase like protein.

    PubMed

    Yadav, Shivani; Srivastava, Alok K; Singh, Dhanajay P; Arora, Dilip K

    2012-11-01

    Oxalic acid plays major role in the pathogenesis by Sclerotinia sclerotiorum; it lowers the pH of nearby environment and creates the favorable condition for the infection. In this study we examined the degradation of oxalic acid through oxalate oxidase and biocontrol of Sclerotinia sclerotiorum. A survey was conducted to collect the rhizospheric soil samples from Indo-Gangetic Plains of India to isolate the efficient fungal strains able to tolerate oxalic acid. A total of 120 fungal strains were isolated from root adhering soils of different vegetable crops. Out of 120 strains a total of 80 isolates were able to grow at 10 mM of oxalic acid whereas only 15 isolates were grow at 50 mM of oxalic acid concentration. Then we examined the antagonistic activity of the 15 isolates against Sclerotinia sclerotiorum. These strains potentially inhibit the growth of the test pathogen. A total of three potential strains and two standard cultures of fungi were tested for the oxalate oxidase activity. Strains S7 showed the maximum degradation of oxalic acid (23 %) after 60 min of incubation with fungal extract having oxalate oxidase activity. Microscopic observation and ITS (internally transcribed spacers) sequencing categorized the potential fungal strains into the Aspergillus, Fusarium and Trichoderma. Trichoderma sp. are well studied biocontrol agent and interestingly we also found the oxalate oxidase type activity in these strains which further strengthens the potentiality of these biocontrol agents.

  6. Nanoparticle strategies for cancer therapeutics: Nucleic acids, polyamines, bovine serum amine oxidase and iron oxide nanoparticles (Review).

    PubMed

    Agostinelli, Enzo; Vianello, Fabio; Magliulo, Giuseppe; Thomas, Thresia; Thomas, T J

    2015-01-01

    Nanotechnology for cancer gene therapy is an emerging field. Nucleic acids, polyamine analogues and cytotoxic products of polyamine oxidation, generated in situ by an enzyme-catalyzed reaction, can be developed for nanotechnology-based cancer therapeutics with reduced systemic toxicity and improved therapeutic efficacy. Nucleic acid-based gene therapy approaches depend on the compaction of DNA/RNA to nanoparticles and polyamine analogues are excellent agents for the condensation of nucleic acids to nanoparticles. Polyamines and amine oxidases are found in higher levels in tumours compared to that of normal tissues. Therefore, the metabolism of polyamines spermidine and spermine, and their diamine precursor, putrescine, can be targets for antineoplastic therapy since these naturally occurring alkylamines are essential for normal mammalian cell growth. Intracellular polyamine concentrations are maintained at a cell type-specific set point through the coordinated and highly regulated interplay between biosynthesis, transport, and catabolism. In particular, polyamine catabolism involves copper-containing amine oxidases. Several studies showed an important role of these enzymes in developmental and disease-related processes in animals through the control of polyamine homeostasis in response to normal cellular signals, drug treatment, and environmental and/or cellular stress. The production of toxic aldehydes and reactive oxygen species (ROS), H2O2 in particular, by these oxidases suggests a mechanism by which amine oxidases can be exploited as antineoplastic drug targets. The combination of bovine serum amine oxidase (BSAO) and polyamines prevents tumour growth, particularly well if the enzyme has been conjugated with a biocompatible hydrogel polymer. The findings described herein suggest that enzymatically formed cytotoxic agents activate stress signal transduction pathways, leading to apoptotic cell death. Consequently, superparamagnetic nanoparticles or other

  7. Effects of salicylic acid on alternative pathway respiration and alternative oxidase expression in tobacco calli.

    PubMed

    Lei, Tao; Yan, Ying-Cai; Xi, De-Hui; Feng, Hong; Sun, Xin; Zhang, Fan; Xu, Wei-Lin; Liang, Hou-Guo; Lin, Hong-Hui

    2008-01-01

    The alternative pathway (AP) respiration of plants is a cyanide-resistant and non-phosphorylating electron transport pathway in mitochondria. Alternative oxidase (AOX) is the terminal oxidase of the AP and exists in plant mitochondria as two states: the reduced, noncovalently linked state or the oxidized, covalently cross-linked state. In the present study, the effects of 20 microM exogenous salicylic acid (SA) on both AP activity and AOX expression in mitochondria of tobacco (Nicotiana rustica L. cv. yellow flower) calli were investigated. The results showed that SA treatment enhanced the AP activity. During the process of SA treatment, the AP activity increased dramatically and achieved the peak value after 8 h of treatment. Then it declined until 16 h, and maintained a steady level between 16 and 24 h. Changes in both the total AOX protein level and the reduced state were in accordance with the AP activity, but the oxidized state changed differently. The aox1 gene transcript level also showed a similar change as the AP activity and AOX protein level. The induction of AOX expression by low concentrations of SA was inferred through a reactive oxygen species (ROS)-independent pathway. These results indicate that the enhancement of AP activity in response to SA is correlated to the expression of AOX, and the reduced, non-covalently linked state of AOX plays an important role during this process.

  8. In vitro oxidation of indoleacetic acid by soluble auxin-oxidases and peroxidases from maize roots. [Zea mays L

    SciTech Connect

    Beffa, R.; Martin, H.V.; Pilet, P.E. )

    1990-10-01

    Soluble auxin-oxidases were extracted from Zea mays L. cv LG11 apical root segments and partially separated from peroxidases (EC 1.11.1.7) by size-exclusion chromatography. Auxin-oxidases were resolved into one main peak corresponding to a molecular mass of 32.5 kilodaltons and a minor peak at 54.5 kilodaltons. Peroxidases were separated into at least four peaks, with molecular masses from 32.5 to 78 kilodaltons. In vitro activity of indoleacetic acid-oxidases was dependent on the presence of MnCl{sub 2} and p-coumaric acid. Compound(s) present in the crude extract and several synthetic auxin transport inhibitors (including 2,3,5-triiodobenzoic acid and N-1-naphthylphthalamic acid) inhibited auxin-oxidase activity, but had no effect on peroxidases. The products resulting from the in vitro enzymatic oxidation of ({sup 3}H)indoleacetic acid were separated by HPLC and the major metabolite was found to cochromatograph with indol-3yl-methanol.

  9. Effect of L-amino acid oxidase from Calloselasma rhodosthoma snake venom on human neutrophils.

    PubMed

    Pontes, Adriana S; da S Setúbal, Sulamita; Xavier, Caroline V; Lacouth-Silva, Fabianne; Kayano, Anderson M; Pires, Weverson L; Nery, Neriane Monteiro; Boeri de Castro, Onassis; da Silva, Silvana D; Calderon, Leonardo A; Stábeli, Rodrigo G; Soares, Andreimar M; Zuliani, Juliana P

    2014-03-01

    The in vitro effects of LAAO, an l-amino acid oxidase isolated from Calloselasma rhodosthoma snake venom, on isolated human neutrophil function were investigated. LAAO showed no toxicity on neutrophils. At non-cytotoxic concentrations, LAAO induced the superoxide anion production by isolated human neutrophil. This toxin, in its native form, is also able to stimulate the production of hydrogen peroxide in neutrophils, suggesting that its primary structure is essential for stimulation the cell. Moreover, the incubation of LAAO and phenol red medium did not induce the production of hydrogen peroxide. Furthermore, LAAO was able to stimulate neutrophils to release proinflammatory mediators such as IL-8 and TNF-α as well as NETs liberation. Together, the data showed that the LAAO triggers relevant proinflammatory events. Particular regions of the molecule distinct from the LAAO catalytic site may be involved in the onset of inflammatory events.

  10. Identification, cloning, and expression of L-amino acid oxidase from marine Pseudoalteromonas sp. B3.

    PubMed

    Yu, Zhiliang; Zhou, Ning; Qiao, Hua; Qiu, Juanping

    2014-01-01

    L-amino acid oxidase (LAAO) is attracting more attentions due to its broad and important biological functions. Recently, an LAAO-producing marine microorganism (strain B3) was isolated from the intertidal zone of Dinghai sea area, China. Physiological, biochemical, and molecular identifications together with phylogenetic analysis congruously suggested that it belonged to the genus Pseudoalteromonas. Therefore, it was designated as Pseudoalteromonas sp. B3. Its capability of LAAO production was crossly confirmed by measuring the products of H2O2, a-keto acids, and NH4+ in oxidization reaction. Two rounds of PCR were performed to gain the entire B3-LAAO gene sequence of 1608 bps in length encoding for 535 amino acid residues. This deduced amino acid sequence showed 60 kDa of the calculated molecular mass, supporting the SDS-PAGE result. Like most of flavoproteins, B3-LAAO also contained two conserved typical motifs, GG-motif and βαβ-dinucleotide-binding domain motif. On the other hand, its unique substrate spectra and sequence information suggested that B3-LAAO was a novel LAAO. Our results revealed that it could be functionally expressed in E. coli BL21(DE3) using vectors, pET28b(+) and pET20b(+). However, compared with the native LAAO, the expression level of the recombinant one was relatively low, most probably due to the formation of inclusion bodies. Several solutions are currently being conducted in our lab to increase its expression level.

  11. Contributions of spinal D-amino acid oxidase to chronic morphine-induced hyperalgesia.

    PubMed

    Ma, Shuai; Li, Xin-Yan; Gong, Nian; Wang, Yong-Xiang

    2015-12-10

    Spinal D-amino acid oxidase (DAAO) is an FAD-dependent peroxisomal flavoenzyme which mediates the conversion of neutral and polar D-amino acids (including D-serine) to the corresponding α-keto acids, and simultaneously produces hydrogen peroxide and ammonia. This study has aimed to explore the potential contributions of spinal DAAO and its mediated hydrogen peroxide/D-serine metabolism to the development of morphine-induced hyperalgesia. Bi-daily subcutaneous injections of morphine to mice over 7 days induced thermal hyperalgesia as measured by both the hot-plate and tail-immersion tests, and spinal astroglial activation with increased spinal gene expression of DAAO, glial fibrillary acidic protein (GFAP) and pro-inflammatory cytokines (interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α)). Subcutaneous injections of the potent DAAO inhibitor CBIO (5-chloro-benzo[D]isoxazol-3-ol) prevented and reversed the chronic morphine-induced hyperalgesia. CBIO also inhibited both astrocyte activation and the expression of pro-inflammatory cytokines. Intrathecal injection of the hydrogen peroxide scavenger PBN (phenyl-N-tert-butylnitrone) and of catalase completely reversed established morphine hyperalgesia, whereas subcutaneous injections of exogenous D-serine failed to alter chronic morphine-induced hyperalgesia. These results provided evidence that spinal DAAO and its subsequent production of hydrogen peroxide rather than the D-serine metabolism contributed to the development of morphine-induced hyperalgesia.

  12. Involvement of Peroxidase and Indole-3-acetic Acid Oxidase Isozymes from Pear, Tomato, and Blueberry Fruit in Ripening.

    PubMed

    Frenkel, C

    1972-05-01

    Protein extracts were obtained from climacteric fruits (pear, tomato) and nonclimacteric fruits (blueberry) during various stages of ripening. The use of a gel electrophoresis technique revealed a consistent reinforcement in indoleacetic acid oxidase but not in peroxidase isozymes during ripening. The significance of the results is discussed in relation to the resistance of fruits to ripening and ethylene action.

  13. Fabrication of enzyme reactor utilizing magnetic porous polymer membrane for screening D-Amino acid oxidase inhibitors.

    PubMed

    Jiang, Jun Fang; Qiao, Juan; Mu, Xiao Yu; Moon, Myeong Hee; Qi, Li

    2017-04-01

    In this work, a unique D-amino acid oxidase reactor for enhanced enzymolysis efficiency is presented. A kind of magnetic polymer matrices, composed of iron oxide nanoparticles and porous polymer membrane (poly styrene-co-maleic anhydride), was prepared. With covalent bonding D-Amino acid oxidase on the surface of the matrices and characterization of scanning electron microscope and vibrating sample magnetometer, it demonstrated that the membrane enzyme reactor was successfully constructed. The enzymolysis efficiency of the enzyme reactor was evaluated and the apparent Michaelis-Menten constants of D-Amino acid oxidase were determined (Km was 1.10mM, Vmax was 23.8mMmin(-1)) by a chiral ligand exchange capillary electrophoresis protocol with methionine as the substrate. The results indicated that the enzyme reactor could exhibit good stability and excellent reusability. Importantly, because the enzyme and the substrate could be confined into the pores of the matrices, the enzyme reactor displayed the improved enzymolysis efficiency due to the confinement effect. Further, the prepared enzyme reactor was applied for D-Amino acid oxidase inhibitors screening. It has displayed that the proposed protocol could pave a new way for fabrication of novel porous polymer membrane based enzyme reactors to screen enzyme inhibitors.

  14. Myeloperoxidase amplified high glucose-induced endothelial dysfunction in vasculature: Role of NADPH oxidase and hypochlorous acid.

    PubMed

    Tian, Rong; Ding, Yun; Peng, Yi-Yuan; Lu, Naihao

    2017-03-11

    Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-derived reactive oxygen species (ROS) such as superoxide and hydrogen peroxide (H2O2), have emerged as important molecules in the pathogenesis of diabetic endothelial dysfunction. Additionally, neutrophils-derived myeloperoxidase (MPO) and MPO-catalyzed hypochlorous acid (HOCl) play important roles in the vascular injury. However, it is unknown whether MPO can use vascular-derived ROS to induce diabetic endothelial dysfunction. In the present study, we demonstrated that NADPH oxidase was the main source of ROS formation in high glucose-cultured human umbilical vein endothelial cells (HUVECs), and played a critical role in high glucose-induced endothelial dysfunction such as cell apoptosis, loss of cell viability and reduction of nitric oxide (NO). However, the addition of MPO could amplify the high glucose-induced endothelial dysfunction which was inhibited by the presence of apocynin (NADPH oxidase inhibitor), catalase (H2O2 scavenger), or methionine (HOCl scavenger), demonstrating the contribution of NADPH oxidase-H2O2-MPO-HOCl pathway in the MPO/high glucose-induced vascular injury. In high glucose-incubated rat aortas, MPO also exacerbated the NADPH oxidase-induced impairment of endothelium-dependent relaxation. Consistent with these in vitro data, in diabetic rat aortas, both MPO expresion and NADPH oxidase activity were increased while the endothelial function was simultaneously impaired. The results suggested that vascular-bound MPO could amplify high glucose-induced vascular injury in diabetes. MPO-NADPH oxidase-HOCl may represent an important pathogenic pathway in diabetic vascular diseases.

  15. Enzymatic production of α-ketoglutaric acid from l-glutamic acid via l-glutamate oxidase.

    PubMed

    Niu, Panqing; Dong, Xiaoxiang; Wang, Yuancai; Liu, Liming

    2014-06-10

    In this study, a novel strategy for α-ketoglutaric acid (α-KG) production from l-glutamic acid using recombinant l-glutamate oxidase (LGOX) was developed. First, by analyzing the molecular structure characteristics of l-glutamic acid and α-KG, LGOX was found to be the best catalyst for oxidizing the amino group of l-glutamic acid to a ketonic group without the need for exogenous cofactor. Then the LGOX gene was expressed in Escherichia coli BL21 (DE3) in a soluble and active form, and the recombinant LGOX activity reached to a maximum value of 0.59U/mL at pH 6.5, 30°C. Finally, the maximum α-KG concentration reached 104.7g/L from 110g/L l-glutamic acid in 24h, under the following optimum conditions: 1.5U/mL LGOX, 250U/mL catalase, 3mM MnCl2, 30°C, and pH 6.5.

  16. Recombinant expression and characterization of a L-amino acid oxidase from the fungus Rhizoctonia solani.

    PubMed

    Hahn, Katharina; Neumeister, Katrin; Mix, Andreas; Kottke, Tilman; Gröger, Harald; Fischer von Mollard, Gabriele

    2017-04-01

    L-Amino acid oxidases (L-AAOs) catalyze the oxidative deamination of L-amino acids to the corresponding α-keto acids, ammonia, and hydrogen peroxide. L-AAOs are homodimeric enzymes with FAD as a non-covalently bound cofactor. They are of potential interest for biotechnological applications. However, heterologous expression has not succeeded in producing large quantities of active recombinant L-AAOs with a broad substrate spectrum so far. Here, we report the heterologous expression of an active L-AAO from the fungus Rhizoctonia solani in Escherichia coli as a fusion protein with maltose-binding protein (MBP) as a solubility tag. After purification, it was possible to remove the MBP-tag proteolytically without influencing the enzyme activity. MBP-rsLAAO1 and 9His-rsLAAO1 converted basic and large hydrophobic L-amino acids as well as methyl esters of these L-amino acids. The progress of the conversion of L-phenylalanine and L-leucine into the corresponding α-keto acids was determined by HPLC and (1)H-NMR analysis of reaction mixtures, respectively. Enzymatic activity was stimulated 50-100-fold by SDS treatment. K m values ranging from 0.9-10 mM and v max values from 3 to 10 U mg(-1) were determined after SDS activation of 9His-rsLAAO1 for the best substrates. The enzyme displayed a broad pH optimum between pH 7.0 and 9.5. In summary, a successful overexpression of recombinant L-AAO in E. coli was established that results in a promising enzymatic activity and a broad substrate spectrum for biotechnological application.

  17. Molecular characterization of L-amino acid oxidase from king cobra venom.

    PubMed

    Jin, Yang; Lee, Wen-Hui; Zeng, Lin; Zhang, Yun

    2007-09-15

    An L-amino acid oxidase from Ophiophagus hannah snake venom (Oh-LAAO) was purified by successive gel filtration, ion-exchange and heparin chromatography. Oh-LAAO did not induce platelet aggregation; however, it had potent inhibitory activity on platelet aggregation induced by ADP and U46619, but showed no effect on platelet aggregation induced by thrombin, mucetin, ristocetin and stejnulxin. By RT-PCR and 5'-RACE methods, the complete Oh-LAAO cDNA was cloned from the venom gland total RNA preparations. The cDNA sequence contains an open-reading frame (ORF) of 1476-bp, which encodes a protein of 491 amino acids comprising a signal peptide of 25 amino acids and 466-residue mature protein. The predicted protein sequence of Oh-LAAO was confirmed by N-terminal and trypsin-digested internal peptides sequencing together with peptide mass fingerprinting. cDNAs encoding for ORF of LAAOs from Bungarus fasciatus and B. multicinctus were cloned and reported in this study. In addition, partial cDNA encoding for Naja atra LAAO was also reported. Oh-LAAO shared approximately 50% protein sequence identity with other known snake venom LAAOs. Phylogenetic analysis indicated that Oh-LAAO is evolutionary distant to other snake venom LAAOs.

  18. Identification of Crucial Amino Acids in Mouse Aldehyde Oxidase 3 That Determine Substrate Specificity

    PubMed Central

    Mahro, Martin; Brás, Natércia F.; Cerqueira, Nuno M. F. S. A.; Teutloff, Christian; Coelho, Catarina; Romão, Maria João; Leimkühler, Silke

    2013-01-01

    In order to elucidate factors that determine substrate specificity and activity of mammalian molybdo-flavoproteins we performed site directed mutagenesis of mouse aldehyde oxidase 3 (mAOX3). The sequence alignment of different aldehyde oxidase (AOX) isoforms identified variations in the active site of mAOX3 in comparison to other AOX proteins and xanthine oxidoreductases (XOR). Based on the structural alignment of mAOX3 and bovine XOR, differences in amino acid residues involved in substrate binding in XORs in comparison to AOXs were identified. We exchanged several residues in the active site to the ones found in other AOX homologues in mouse or to residues present in bovine XOR in order to examine their influence on substrate selectivity and catalytic activity. Additionally we analyzed the influence of the [2Fe-2S] domains of mAOX3 on its kinetic properties and cofactor saturation. We applied UV-VIS and EPR monitored redox-titrations to determine the redox potentials of wild type mAOX3 and mAOX3 variants containing the iron-sulfur centers of mAOX1. In addition, a combination of molecular docking and molecular dynamic simulations (MD) was used to investigate factors that modulate the substrate specificity and activity of wild type and AOX variants. The successful conversion of an AOX enzyme to an XOR enzyme was achieved exchanging eight residues in the active site of mAOX3. It was observed that the absence of the K889H exchange substantially decreased the activity of the enzyme towards all substrates analyzed, revealing that this residue has an important role in catalysis. PMID:24358164

  19. The stabilizing effects of immobilization in D-amino acid oxidase from Trigonopsis variabilis

    PubMed Central

    Dib, Iskandar; Nidetzky, Bernd

    2008-01-01

    Background Immobilization of Trigonopsis variabilis D-amino acid oxidase (TvDAO) on solid support is the key to a reasonably stable performance of this enzyme in the industrial process for the conversion of cephalosporin C as well as in other biocatalytic applications. Results To provide a mechanistic basis for the stabilization of the carrier-bound oxidase we analyzed the stabilizing effects of immobilization in TvDAO exposed to the stress of elevated temperature and operational conditions. Two different strategies of immobilization were used: multi-point covalent binding to epoxy-activated Sepabeads EC-EP; and non-covalent oriented immobilization of the enzyme through affinity of its N-terminal Strep-tag to Strep-Tactin coated on insoluble particles. At 50°C, the oriented immobilizate was not stabilized as compared to the free enzyme. The structure of TvDAO was stabilized via covalent attachment to Sepabeads EC-EP but concomitantly, binding of the FAD cofactor was weakened. FAD release from the enzyme into solution markedly reduced the positive effect of immobilization on the overall stability of TvDAO. Under conditions of substrate conversion in a bubble-aerated stirred tank reactor, both immobilization techniques as well as the addition of the surfactant Pluronic F-68 stabilized TvDAO by protecting the enzyme from the deleterious effect of gas-liquid interfaces. Immobilization of TvDAO on Sepabeads EC-EP however stabilized the enzyme beyond this effect and led to a biocatalyst that could be re-used in multiple cycles of substrate conversion. Conclusion Multi-point covalent attachment of TvDAO on an isoluble porous carrier provides stabilization against the denaturing effects of high temperature and exposure to a gas-liquid interface. Improvement of binding of the FAD cofactor, probably by using methods of protein engineering, would further enhance the stability of the immobilized enzyme. PMID:18798979

  20. Fermentation and alternative oxidase contribute to the action of amino acid biosynthesis-inhibiting herbicides.

    PubMed

    Zulet, Amaia; Gil-Monreal, Miriam; Zabalza, Ana; van Dongen, Joost T; Royuela, Mercedes

    2015-03-01

    Acetolactate synthase inhibitors (ALS-inhibitors) and glyphosate (GLP) are two classes of herbicide that act by the specific inhibition of an enzyme in the biosynthetic pathway of branched-chain or aromatic amino acids, respectively. The physiological effects that are detected after application of these two classes of herbicides are not fully understood in relation to the primary biochemical target inhibition, although they have been well documented. Interestingly, the two herbicides' toxicity includes some common physiological effects suggesting that they kill the treated plants by a similar pattern despite targeting different enzymes. The induction of aerobic ethanol fermentation and alternative oxidase (AOX) are two examples of these common effects. The objective of this work was to gain further insight into the role of fermentation and AOX induction in the toxic consequences of ALS-inhibitors and GLP. For this, Arabidopsis T-DNA knockout mutants of alcohol dehydrogenase (ADH) 1 and AOX1a were used. The results found in wild-type indicate that both GLP and ALS-inhibitors reduce ATP production by inducing fermentation and alternative respiration. The main physiological effects in the process of herbicide activity upon treated plants were accumulation of carbohydrates and total free amino acids. The effects of the herbicides on these parameters were less pronounced in mutants compared to wild-type plants. The role of fermentation and AOX regarding pyruvate availability is also discussed.

  1. Synthesis and evaluation of quinazoline amino acid derivatives as mono amine oxidase (MAO) inhibitors.

    PubMed

    Khattab, Sherine Nabil; Haiba, Nesreen Saied; Asal, Ahmed Mosaad; Bekhit, Adnan A; Amer, Adel; Abdel-Rahman, Hamdy M; El-Faham, Ayman

    2015-07-01

    A series of quinazolinone amino acid ester and quinazolinone amino acid hydrazides were prepared under microwave irradiation as well as conventional condition. The microwave irradiation afforded the product in less reaction time, higher yield and purity. The structures of the synthesized compounds were confirmed by IR, NMR, and elemental analysis. The new synthesized compounds were studied for their monoamine oxidase inhibitory activity. They showed more selective inhibitory activity toward MAO-A than MAO-B. Compounds 7, 10, and 15 showed MAO-A inhibition activity (IC50=3.6×10(-9), 2.8×10(-9), 2.1×10(-9) M, respectively) comparable to that of the standard clorgyline (IC50=2.9×10(-9)M). 2-(2-(Benzo[d][1,3]dioxol-5-yl)-4-oxo-1,2-dihydroquinazolin-3(4H)-yl)acetohydrazide 15 showed selective MAO-A inhibition activity (SI=39524) superior to that of the standard clorgyline (SI=33793). The acute toxicity of the synthesized compounds was determined. In addition, computer-assisted simulated docking experiments were performed to rationalize the biological activity.

  2. Bio-inspired amino acid oxidation by a non-heme iron catalyst modeling the action of 1-aminocyclopropane-1-carboxylic acid oxidase.

    PubMed

    Baráth, Gábor; Kaizer, József; Pap, József Sándor; Speier, Gábor; El Bakkali-Taheri, Nadia; Simaan, A Jalila

    2010-10-21

    In this communication we describe the first example of a biomimetic mononuclear iron complex, [Fe(III)(Salen)Cl] (Salen = N,N'-bis(salicylidene)-ethylenediaminato), that highly selectively and efficiently catalyzes the oxidation of 1-aminocyclopropane-1-carboxylic acid (ACCH), α-aminoisobutyric acid (AIBH), and alanine (ALAH) to ethylene or the corresponding carbonyl compounds, mimicking the action of the non-heme iron enzyme 1-aminocyclopropane-1-carboxylic acid oxidase (ACCO).

  3. Synthesis and bioevaluation of 2-phenyl-4-methyl-1,3-selenazole-5-carboxylic acids as potent xanthine oxidase inhibitors.

    PubMed

    Guan, Qi; Cheng, Zengjin; Ma, Xiaoxue; Wang, Lijie; Feng, Dongjie; Cui, Yuanhang; Bao, Kai; Wu, Lan; Zhang, Weige

    2014-10-06

    A series of 2-phenyl-4-methyl-1,3-selenazole-5-carboxylic acid derivatives (8a-f, 9a-m) were synthesized and evaluated for inhibitory activity against xanthine oxidase in vitro. Structure-activity relationship analyses have also been presented. Most of the target compounds exhibited potency levels in the nanomolar range. Compound 9e emerged as the most potent xanthine oxidase inhibitor (IC50 = 5.5 nM) in comparison to febuxostat (IC50 = 18.6 nM). Steady-state kinetics measurements with the bovine milk enzyme indicated a mixed type inhibition with Ki and Ki' values of 0.9 and 2.3 nM, respectively. A molecular modeling study on compounds 9e was performed to gain an insight into its binding mode with xanthine oxidase, and to provide the basis for further structure-guided design of new non-purine xanthine oxidase inhibitors related with 2-phenyl-4-methyl-1,3-selenazole-5-carboxylic acid scaffold.

  4. Planarian D-amino acid oxidase is involved in ovarian development during sexual induction.

    PubMed

    Maezawa, Takanobu; Tanaka, Hiroyuki; Nakagawa, Haruka; Ono, Mizuki; Aoki, Manabu; Matsumoto, Midori; Ishida, Tetsuo; Horiike, Kihachiro; Kobayashi, Kazuya

    2014-05-01

    To elucidate the molecular mechanisms underlying switching from asexual to sexual reproduction, namely sexual induction, we developed an assay system for sexual induction in the hermaphroditic planarian species Dugesia ryukyuensis. Ovarian development is the initial and essential step in sexual induction, and it is followed by the formation of other reproductive organs, including the testes. Here, we report a function of a planarian D-amino acid oxidase, Dr-DAO, in the control of ovarian development in planarians. Asexual worms showed significantly more widespread expression of Dr-DAO in the parenchymal space than did sexual worms. Inhibition of Dr-DAO by RNAi caused the formation of immature ovaries. In addition, we found that feeding asexual worms 5 specific D-amino acids could induce the formation of immature ovaries that are similar to those observed in Dr-DAO knockdown worms, suggesting that Dr-DAO inhibits the formation of immature ovaries by degrading these D-amino acids. Following sexual induction, Dr-DAO expression was observed in the ovaries. The knockdown of Dr-DAO during sexual induction delayed the maturation of the other reproductive organs, as well as ovary. These findings suggest that Dr-DAO acts to promote ovarian maturation and that complete sexual induction depends on the production of mature ovaries. We propose that Dr-DAO produced in somatic cells prevents the onset of sexual induction in the asexual state, and then after sexual induction, the female germ cells specifically produce Dr-DAO to induce full maturation. Therefore, Dr-DAO produced in somatic and female germline cells may play different roles in sexual induction.

  5. A rational protocol for the successful crystallization of l-amino-acid oxidase from Bothrops atrox

    PubMed Central

    Alves, Raquel Melo; Feliciano, Patricia Rosa; Sampaio, Suely Vilela; Nonato, Maria Cristina

    2011-01-01

    Despite the valuable contributions of robotics and high-throughput approaches to protein crystallization, the role of an experienced crystallographer in the evaluation and rationalization of a crystallization process is still crucial to obtaining crystals suitable for X-ray diffraction measurements. In this work, the difficult task of crystallizing the flavoenzyme l-amino-acid oxidase purified from Bothrops atrox snake venom was overcome by the development of a protocol that first required the identification of a non-amorphous precipitate as a promising crystallization condition followed by the implementation of a methodology that combined crystallization in the presence of oil and seeding techniques. Crystals were obtained and a complete data set was collected to 2.3 Å resolution. The crystals belonged to space group P21, with unit-cell parameters a = 73.64, b = 123.92, c = 105.08 Å, β = 96.03°. There were four protein subunits in the asymmetric unit, which gave a Matthews coefficient V M of 2.12 Å3 Da−1, corresponding to 42% solvent content. The structure has been solved by molecular-replacement techniques. PMID:21505245

  6. Lysyl oxidase-like 4 involvement in retinoic acid epithelial wound healing

    PubMed Central

    Comptour, Aurélie; Rouzaire, Marion; Belville, Corinne; Bonnin, Nicolas; Daniel, Estelle; Chiambaretta, Frédéric; Blanchon, Loïc; Sapin, Vincent

    2016-01-01

    Vitamin A and its active forms (retinoic acids/RAs) are known to have pro-healing properties, but their mechanisms of action are still poorly understood. This work aimed to identify the cellular and molecular processes by which atRA (all-trans RA) improves wound healing, using an in vivo model of mouse corneal alkali burns and an in vitro cellular human corneal epithelial injury model. Regulation by atRA has been studied on most of the cellular events that occur in wound healing. We investigated the direct influence of atRA on a specific target gene known to be involved in the extracellular matrix (ECM) dynamics, one of the pathways contributing to epithelial repair. Our results demonstrate that atRA promotes corneal epithelial wound healing by acting preferentially on migration. The induction of lysyl oxidase-like 4 (LOXL4) expression by atRA in the corneal epithelium environment was established as essential in the mechanism of atRA-dependent wound healing. Our study describes for the first time a direct link between a retinoic-induced gene and protein, LOXL4, and its general clinical pro-healing properties in ECM dynamics. PMID:27597564

  7. Manageable cytotoxicity of nanocapsules immobilizing D-amino acid oxidase via exogenous administration of nontoxic prodrug

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Zhu, Yingchun; Fu, Jingke

    2014-02-01

    D-Amino acid oxidase (DAO), which could catalyze generation of hydrogen peroxide with strong oxidbility and cytotoxicity, has become of interest as a biocatalyst for therapeutic treatments. Herein we report that amino-functional hollow mesoporous silica with large pore size (10.27 nm) and positively charged surface effectively immobilize DAO with negative charge. The adsorption, activity and stability of DAO are demonstrated to depend mainly on the amino-functionalization of surface. Significant cancer cell killing effect is observed when the cells are treated by the nanocapsules entrapping DAO together with D-alanine, showing distinct dose-dependency on concentration of the nanocapsules entrapping DAO or D-alanine. Nevertheless, the toxicity is completely neutralized by the addition of catalase, and anti-tumor effect is not observed when either the nanocapsules entrapping DAO or D-alanine is applied alone. The results indicate that cytotoxicity of the nanocapsules entrapping DAO could be managed by exogenous administration of nontoxic prodrug to tumor tissue, due to the stereoselectivity of DAO and the scarcity of its substrates in mammalian organisms. Thus, the method might be exploited as a potential treatment for cancer therapy.

  8. Characterization and cytotoxicity of L-amino acid oxidase from the venom of king cobra (Ophiophagus hannah).

    PubMed

    Ahn, M Y; Lee, B M; Kim, Y S

    1997-06-01

    The aim of this project was to determine the cytotoxic components from the venom of king cobra, Ophiophagus hannah. Venom was purified by a combination of gel-filtration, ion-exchange and reversed-phase chromatographic steps. The biochemical properties of the cytotoxic component were consistent with those of L-amino acid oxidase. The molecular weight of the enzyme was estimated to be 150,000 by gel filtration and 70,000 under the denaturing conditions of SDS-PAGE, indicating a dimer. It has an isoelectric point of 4.5 and is a glycoprotein. The N-terminal sequence of L-amino acid oxidase from the king cobra venom was determined to be SVINLEESFQEPEYE. The cytotoxicity of L-amino acid oxidase was observed in stomach cancer, murine melanoma, fibrosarcoma, colorectal cancer and Chinese hamster ovary cell lines. Cytotoxicity resulted in the loss of ability in attachment and inhibition of cell proliferation. The cytotoxic protein decreased the level of cell proliferation by 74% according to [3H]thymidine uptake assay. The mechanism of enzyme action may be related to the inhibition of thymidine incorporation and an interaction with DNA.

  9. Activity of D-amino acid oxidase is widespread in the human central nervous system

    PubMed Central

    Sasabe, Jumpei; Suzuki, Masataka; Imanishi, Nobuaki; Aiso, Sadakazu

    2014-01-01

    It has been proposed that D-amino acid oxidase (DAO) plays an essential role in degrading D-serine, an endogenous coagonist of N-methyl-D-aspartate (NMDA) glutamate receptors. DAO shows genetic association with amyotrophic lateral sclerosis (ALS) and schizophrenia, in whose pathophysiology aberrant metabolism of D-serine is implicated. Although the pathology of both essentially involves the forebrain, in rodents, enzymatic activity of DAO is hindbrain-shifted and absent in the region. Here, we show activity-based distribution of DAO in the central nervous system (CNS) of humans compared with that of mice. DAO activity in humans was generally higher than that in mice. In the human forebrain, DAO activity was distributed in the subcortical white matter and the posterior limb of internal capsule, while it was almost undetectable in those areas in mice. In the lower brain centers, DAO activity was detected in the gray and white matters in a coordinated fashion in both humans and mice. In humans, DAO activity was prominent along the corticospinal tract, rubrospinal tract, nigrostriatal system, ponto-/olivo-cerebellar fibers, and in the anterolateral system. In contrast, in mice, the reticulospinal tract and ponto-/olivo-cerebellar fibers were the major pathways showing strong DAO activity. In the human corticospinal tract, activity-based staining of DAO did not merge with a motoneuronal marker, but colocalized mostly with excitatory amino acid transporter 2 and in part with GFAP, suggesting that DAO activity-positive cells are astrocytes seen mainly in the motor pathway. These findings establish the distribution of DAO activity in cerebral white matter and the motor system in humans, providing evidence to support the involvement of DAO in schizophrenia and ALS. Our results raise further questions about the regulation of D-serine in DAO-rich regions as well as the physiological/pathological roles of DAO in white matter astrocytes. PMID:24959138

  10. The antiviral drug acyclovir is a slow-binding inhibitor of (D)-amino acid oxidase.

    PubMed

    Katane, Masumi; Matsuda, Satsuki; Saitoh, Yasuaki; Sekine, Masae; Furuchi, Takemitsu; Koyama, Nobuhiro; Nakagome, Izumi; Tomoda, Hiroshi; Hirono, Shuichi; Homma, Hiroshi

    2013-08-20

    d-Amino acid oxidase (DAO) is a degradative enzyme that is stereospecific for d-amino acids, including d-serine and d-alanine, which are believed to be coagonists of the N-methyl-d-aspartate (NMDA) receptor. To identify a new class of DAO inhibitor(s) that can be used to elucidate the molecular details of the active site environment of DAO, manifold biologically active compounds of microbial origin and pre-existing drugs were screened for their ability to inhibit DAO activity, and several compounds were identified as candidates. One of these compounds, acyclovir (ACV), a well-known antiviral drug used for the treatment of herpesvirus infections, was characterized and evaluated as a novel DAO inhibitor in vitro. Analysis showed that ACV acts on DAO as a reversible slow-binding inhibitor, and interestingly, the time required to achieve equilibrium between DAO, ACV, and the DAO/ACV complex was highly dependent on temperature. The binding mechanism of ACV to DAO was investigated in detail by several approaches, including kinetic analysis, structural modeling of DAO complexed with ACV, and site-specific mutagenesis of an active site residue postulated to be involved in the binding of ACV. The results confirm that ACV is a novel, active site-directed inhibitor of DAO that can be a valuable tool for investigating the structure-function relationships of DAO, including the molecular details of the active site environment of DAO. In particular, it appears that ACV can serve as an active site probe to study the structural basis of temperature-induced conformational changes of DAO.

  11. Activity of D-amino acid oxidase is widespread in the human central nervous system.

    PubMed

    Sasabe, Jumpei; Suzuki, Masataka; Imanishi, Nobuaki; Aiso, Sadakazu

    2014-01-01

    It has been proposed that D-amino acid oxidase (DAO) plays an essential role in degrading D-serine, an endogenous coagonist of N-methyl-D-aspartate (NMDA) glutamate receptors. DAO shows genetic association with amyotrophic lateral sclerosis (ALS) and schizophrenia, in whose pathophysiology aberrant metabolism of D-serine is implicated. Although the pathology of both essentially involves the forebrain, in rodents, enzymatic activity of DAO is hindbrain-shifted and absent in the region. Here, we show activity-based distribution of DAO in the central nervous system (CNS) of humans compared with that of mice. DAO activity in humans was generally higher than that in mice. In the human forebrain, DAO activity was distributed in the subcortical white matter and the posterior limb of internal capsule, while it was almost undetectable in those areas in mice. In the lower brain centers, DAO activity was detected in the gray and white matters in a coordinated fashion in both humans and mice. In humans, DAO activity was prominent along the corticospinal tract, rubrospinal tract, nigrostriatal system, ponto-/olivo-cerebellar fibers, and in the anterolateral system. In contrast, in mice, the reticulospinal tract and ponto-/olivo-cerebellar fibers were the major pathways showing strong DAO activity. In the human corticospinal tract, activity-based staining of DAO did not merge with a motoneuronal marker, but colocalized mostly with excitatory amino acid transporter 2 and in part with GFAP, suggesting that DAO activity-positive cells are astrocytes seen mainly in the motor pathway. These findings establish the distribution of DAO activity in cerebral white matter and the motor system in humans, providing evidence to support the involvement of DAO in schizophrenia and ALS. Our results raise further questions about the regulation of D-serine in DAO-rich regions as well as the physiological/pathological roles of DAO in white matter astrocytes.

  12. Involvement of NADPH oxidase in high-dose phenolic acid-induced pro-oxidant activity on rat mesenteric venules.

    PubMed

    Du, Wen-Yuan; Xiao, Ying; Yao, Jian-Jing; Hao, Zhe; Zhao, Yu-Bin

    2017-01-01

    In the present study, we investigated the potential role of phenolic acids in initiating oxidative damage to microvascular endothelial cells and the underlying mechanism mediating the pro-oxidant action. Male Wistar rats received high doses of phenolic acid [caffeic acid (CA), salvianolic acid B (SAB), chlorogenic acid (ChA) or ferulic acid (FA)]. The creation of reactive oxygen species in mesenteric microcirculation endothelial cells and adherent leukocytes along with venules were assessed using intravital microscopy. The expression levels of NADPH oxidase subunits (Nox4 and p22(phox)) in terminal ileum tissues were determined by western blot analysis. Intravenous injection of high-dose ChA or CA (7 mg/kg) markedly increased the peroxide production in the venular walls and upregulated the protein expression levels of Nox4 and p22(phox) in the ileum tissues, while the same dose of CA and SAB made no difference within the observation period. No changes were observed in the number of leukocytes adhering to the venular walls. High-dose ChA and FA led to an imbalance between the oxidant and antioxidant mechanism by boosting the expression levels of NADPH oxidase. Thus, we clarified the rationale behind the adverse effects of a herbal injection containing high levels of phenolic acid compounds.

  13. Purification and characterization of L-amino acid oxidase from king cobra (Ophiophagus hannah) venom and its effects on human platelet aggregation.

    PubMed

    Li, Z Y; Yu, T F; Lian, E C

    1994-11-01

    Venoms of several snake species contain large amounts of L-amino acid oxidase but its effects on human plasma coagulation and platelet aggregation have not been explored. We have purified L-amino acid oxidase from king cobra venom through CM-Sephadex C-25, Sephadex G-100 and DEAE Sephadex A-50 chromatographies. The purified enzyme has a mol. wt of 135,000 as determined by gel filtration and 65,000 by SDS-PAGE under non-reducing and reducing conditions. Incubation of plasma with L-amino acid oxidase at 200 micrograms/ml did not affect prothrombin time, activated partial thromboplastin time, or thrombin time. Upon addition of L-amino acid oxidase, platelets in platelet-rich plasma were aggregated. The enzyme-induced aggregation was abolished by catalase. The aggregation was also inhibited by indomethacin, aspirin, ethylenediaminetetraacetate, sodium nitroprusside, prostaglandin E1, mepacrine and verapamil, but not by heparin, hirudin, creatine phosphate/creatine phosphokinase or antimycin/2-deoxy-D-glucose. These results suggest that L-amino acid oxidase induces human platelet aggregation through the formation of H2O2, and subsequent thromboxane A2 synthesis requiring Ca2+ but independent of ADP release. The platelet aggregation caused by L-amino acid oxidase is likely to contribute to toxicity inflicted by cobra venom.

  14. Thermal stability of ascorbic acid and ascorbic acid oxidase in african cowpea leaves ( Vigna unguiculata ) of different maturities.

    PubMed

    Wawire, Michael; Oey, Indrawati; Mathooko, Francis; Njoroge, Charles; Shitanda, Douglas; Hendrickx, Marc

    2011-03-09

    Cowpea, an African leafy vegetable ( Vigna unguiculata ), contains a high level of vitamin C. The leaves harvested at 4-9 weeks are highly prone to vitamin C losses during handling and processing. Therefore, the purpose of this research was to study the effect of thermal treatment on the stability of ascorbic acid oxidase (AAO), total vitamin C content (l-ascorbic acid, l-AA), and dehydroascorbic acid (DHAA) and l-AA/DHAA ratio in cowpea leaves harvested at different maturities (4, 6, and 8 weeks old). The results showed that AAO activity, total vitamin C content, and l-AA/DHAA ratio in cowpea leaves increased with increasing maturity (up to 8 weeks). Eight-week-old leaves were the best source of total vitamin C and showed a high ratio of l-AA/DHAA (4:1). Thermal inactivation of AAO followed first-order reaction kinetics. Heating at temperatures above 90 °C for short times resulted in a complete AAO inactivation, resulting in a protective effect of l-AA toward enzyme-catalyzed oxidation. Total vitamin C in young leaves (harvested at 4 and 6 weeks) was predominantly in the form of DHAA, and therefore temperature treatment at 30-90 °C for 10 min decreased the total vitamin C content, whereas total vitamin C in 8-week-old cowpea leaves was more than 80% in the form of l-AA, so that a high retention of the total vitamin C can be obtained even after heating and/or reheating (30-90 °C for 10 min) before consumption. The results indicated that the stability of total vitamin C in situ was strongly dependent on the plant maturity stage and the processing conditions applied.

  15. Antiproliferative activity of king cobra (Ophiophagus hannah) venom L-amino acid oxidase.

    PubMed

    Li Lee, Mui; Chung, Ivy; Yee Fung, Shin; Kanthimathi, M S; Hong Tan, Nget

    2014-04-01

    King cobra (Ophiophagus hannah) venom L-amino acid oxidase (LAAO), a heat-stable enzyme, is an extremely potent antiproliferative agent against cancer cells when compared with LAAO isolated from other snake venoms. King cobra venom LAAO was shown to exhibit very strong antiproliferative activities against MCF-7 (human breast adenocarcinoma) and A549 (human lung adenocarcinoma) cells, with an IC50 value of 0.04±0.00 and 0.05±0.00 μg/mL, respectively, after 72-hr treatment. In comparison, its cytotoxicity was about 3-4 times lower when tested against human non-tumourigenic breast (184B5) and lung (NL 20) cells, suggesting selective antitumour activity. Furthermore, its potency in MCF-7 and A549 cell lines was greater than the effects of doxorubicin, a clinically established cancer chemotherapeutic agent, which showed an IC50 value of 0.18±0.03 and 0.63±0.21 μg/mL, respectively, against the two cell lines. The selective cytotoxic action of the LAAO was confirmed by phycoerythrin (PE) annexin V/7-amino-actinomycin (AAD) apoptotic assay, in which a significant increase in apoptotic cells was observed in LAAO-treated tumour cells than in their non-tumourigenic counterparts. The ability of LAAO to induce apoptosis in tumour cells was further demonstrated using caspase-3/7 and DNA fragmentation assays. We also determined that this enzyme may target oxidative stress in its killing of tumour cells, as its cytotoxicity was significantly reduced in the presence of catalase (a H2O2 scavenger). In view of its heat stability and selective and potent cytotoxic action on cancer cells, king cobra venom LAAO can be potentially developed for treating solid tumours.

  16. Modulation of NMDA receptor function by inhibition of D-amino acid oxidase in rodent brain.

    PubMed

    Strick, Christine A; Li, Cheryl; Scott, Liam; Harvey, Brian; Hajós, Mihály; Steyn, Stefanus J; Piotrowski, Mary A; James, Larry C; Downs, James T; Rago, Brian; Becker, Stacey L; El-Kattan, Ayman; Xu, Youfen; Ganong, Alan H; Tingley, F David; Ramirez, Andres D; Seymour, Patricia A; Guanowsky, Victor; Majchrzak, Mark J; Fox, Carol B; Schmidt, Christopher J; Duplantier, Allen J

    2011-01-01

    Observations that N-Methyl-D-Aspartate (NMDA) antagonists produce symptoms in humans that are similar to those seen in schizophrenia have led to the current hypothesis that schizophrenia might result from NMDA receptor hypofunction. Inhibition of D-amino acid oxidase (DAAO), the enzyme responsible for degradation of D-serine, should lead to increased levels of this co-agonist at the NMDA receptor, and thereby provide a therapeutic approach to schizophrenia. We have profiled some of the preclinical biochemical, electrophysiological, and behavioral consequences of administering potent and selective inhibitors of DAAO to rodents to begin to test this hypothesis. Inhibition of DAAO activity resulted in a significant dose and time dependent increase in D-serine only in the cerebellum, although a time delay was observed between peak plasma or brain drug concentration and cerebellum D-serine response. Pharmacokinetic/pharmacodynamic (PK/PD) modeling employing a mechanism-based indirect response model was used to characterize the correlation between free brain drug concentration and D-serine accumulation. DAAO inhibitors had little or no activity in rodent models considered predictive for antipsychotic activity. The inhibitors did, however, affect cortical activity in the Mescaline-Induced Scratching model, produced a modest but significant increase in NMDA receptor-mediated synaptic currents in primary neuronal cultures from rat hippocampus, and resulted in a significant increase in evoked hippocampal theta rhythm, an in vivo electrophysiological model of hippocampal activity. These findings demonstrate that although DAAO inhibition did not cause a measurable increase in D-serine in forebrain, it did affect hippocampal and cortical activity, possibly through augmentation of NMDA receptor-mediated currents.

  17. Engineering the properties of D-amino acid oxidases by a rational and a directed evolution approach.

    PubMed

    Pollegioni, Loredano; Sacchi, Silvia; Caldinelli, Laura; Boselli, Angelo; Pilone, Mirella S; Piubelli, Luciano; Molla, Gianluca

    2007-12-01

    D-amino acid oxidase (DAAO) is a FAD-containing flavoprotein that dehydrogenates the D-isomer of amino acids to the corresponding imino acids, coupled with the reduction of FAD. The cofactor then reoxidizes on molecular oxygen and the imino acid hydrolyzes spontaneously to the alpha-keto acid and ammonia. In vitro DAAO displays broad substrate specificity, acting on several neutral and basic D-amino acids: the most efficient substrates are amino acids with hydrophobic side chains. D-aspartic acid and D-glutamic acid are not substrates for DAAO. Through the years, it has been the subject of a number of structural, functional and kinetic investigations. The most recent advances are represented by site-directed mutagenesis studies and resolution of the 3D-structure of the enzymes from pig, human and yeast. The two approaches have given us a deeper understanding of the structure-function relationships and promoted a number of investigations aimed at the modulating the protein properties. By a rational and/or a directed evolution approach, DAAO variants with altered substrate specificity (e.g., active on acidic or on all D-amino acids), increased stability (e.g., stable up to 60 degrees C), modified interaction with the flavin cofactor, and altered oligomeric state were produced. The aim of this paper is to provide an overview of the most recent research on the engineering of DAAOs to illustrate their new intriguing properties, which also have enabled us to pursue new biotechnological applications.

  18. Lao Basic Course, Volume 1.

    ERIC Educational Resources Information Center

    Yates, Warren G.; Sayasithsena, Souksomboun

    This book comprises a "set of guidelines for conversational interplay between students and their native-speaking Lao instructor." A student who successfully completes the course should be able to order a simple meal, ask for a room in a hotel, ask and give street directions, tell time, handle travel requirements, and use expressions of…

  19. Induction of apoptosis in yeast by L-amino acid oxidase from the Malayan pit viper Calloselasma rhodostoma.

    PubMed

    Ande, Sudharsana Rao; Fussi, Heike; Knauer, Heide; Murkovic, Michael; Ghisla, Sandro; Fröhlich, Kai-Uwe; Macheroux, Peter

    2008-05-01

    Here we report for the first time that L-amino acid oxidase (LAAO), a major component of snake venom, induces apoptosis in yeast. The causative agent for induction of apoptosis has been shown to be hydrogen peroxide, produced by the enzymatic activity of LAAO. However, the addition of catalase, a specific hydrogen peroxide scavenger, does not prevent cell demise completely. Intriguingly, depletion of leucine from the medium by LAAO and the interaction of LAAO with yeast cells are shown to be the major factors responsible for cell demise in the presence of catalase.

  20. A novel L-amino acid oxidase from Trichoderma harzianum ETS 323 associated with antagonism of Rhizoctonia solani.

    PubMed

    Yang, Chia-Ann; Cheng, Chi-Hua; Lo, Chaur-Tsuen; Liu, Shu-Ying; Lee, Jeng-Woei; Peng, Kou-Cheng

    2011-05-11

    Trichoderma spp. are used as biocontrol agents against phytopathogens such as Rhizoctonia solani, but their biocontrol mechanisms are poorly understood. A novel L-amino oxidase (Th-LAAO) was identified from the extracellular proteins of Trichoderma harzianum ETS 323. Here, we show a FAD-binding glycoprotein with the best substrate specificity constant for L-phenylalanine. Although the amino acid sequence of Th-LAAO revealed limited homology (16-24%) to other LAAO members, a highly conserved FAD-binding motif was identified in the N-terminus. Th-LAAO was shown to be a homodimeric protein, but the monomeric form was predominant when grown in the presence of deactivated Rhizoctonia solani. Furthermore, in vitro assays demonstrated that Th-LAAO had an antagonistic effect against Rhizoctonia solani and a stimulatory one on hyphal density and sporulation in T. harzianum ETS 323. These findings further our understanding of T. harzianum as a biocontrol agent and provide insight into the biological function of l-amino acid oxidase.

  1. Distribution in Different Organisms of Amino Acid Oxidases with FAD or a Quinone As Cofactor and Their Role as Antimicrobial Proteins in Marine Bacteria

    PubMed Central

    Campillo-Brocal, Jonatan C.; Lucas-Elío, Patricia; Sanchez-Amat, Antonio

    2015-01-01

    Amino acid oxidases (AAOs) catalyze the oxidative deamination of amino acids releasing ammonium and hydrogen peroxide. Several kinds of these enzymes have been reported. Depending on the amino acid isomer used as a substrate, it is possible to differentiate between l-amino acid oxidases and d-amino acid oxidases. Both use FAD as cofactor and oxidize the amino acid in the alpha position releasing the corresponding keto acid. Recently, a novel class of AAOs has been described that does not contain FAD as cofactor, but a quinone generated by post-translational modification of residues in the same protein. These proteins are named as LodA-like proteins, after the first member of this group described, LodA, a lysine epsilon oxidase synthesized by the marine bacterium Marinomonas mediterranea. In this review, a phylogenetic analysis of all the enzymes described with AAO activity has been performed. It is shown that it is possible to recognize different groups of these enzymes and those containing the quinone cofactor are clearly differentiated. In marine bacteria, particularly in the genus Pseudoalteromonas, most of the proteins described as antimicrobial because of their capacity to generate hydrogen peroxide belong to the group of LodA-like proteins. PMID:26694422

  2. Surface modification of polyvinyl alcohol/malonic acid nanofibers by gaseous dielectric barrier discharge plasma for glucose oxidase immobilization

    NASA Astrophysics Data System (ADS)

    Afshari, Esmail; Mazinani, Saeedeh; Ranaei-Siadat, Seyed-Omid; Ghomi, Hamid

    2016-11-01

    Polymeric nanofiber prepares a suitable situation for enzyme immobilization for variety of applications. In this research, we have fabricated polyvinyl alcohol (PVA)/malonic acid nanofibers using electrospinning. After fabrication of nanofibers, the effect of air, nitrogen, CO2, and argon DBD (dielectric barrier discharge) plasmas on PVA/malonic acid nanofibers were analysed. Among them, air plasma had the most significant effect on glucose oxidase (GOx) immobilization. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrum analysis and X-ray photoelectron spectroscopy (XPS) results revealed that in case of air plasma modified nanofibers, the carboxyl groups on the surface are increased. The scanning electron microscopy (SEM) images showed that, after GOx immobilization, the modified nanofibers with plasma has retained its nanofiber structure. Finally, we analysed reusability and storage stability of GOx immobilized on plasma modified and unmodified nanofibers. The results were more satisfactory for modified nanofibers with respect to unmodified ones.

  3. Lao Language Competencies for Peace Corps Volunteers in the Lao People's Democratic Republic. Draft.

    ERIC Educational Resources Information Center

    de Abrew, Kamini; Khamphasinovanh, Thong

    This Lao language textbook is the second draft of a book developed for teaching Lao to United States Peace Corps volunteers (PCVs) and is designed to be used with a Lao language instructor familiar with competency based curricula. It is not designed for self-instruction, although after some hours of use, students may be familiar enough with the…

  4. Synthesis and evaluation of xanthine oxidase inhibitory and antioxidant activities of 2-arylbenzo[b]furan derivatives based on salvianolic acid C.

    PubMed

    Tang, Hong-Jin; Zhang, Xiao-Wei; Yang, Lin; Li, Wei; Li, Jia-Huang; Wang, Jin-Xin; Chen, Jun

    2016-11-29

    Xanthine oxidase (XO) is the key enzyme in humans which is related to a variety of diseases such as gout, hyperuricemia and cardiovascular diseases. In this work, a series of 2-arylbenzo[b]furan derivatives were synthesized based on salvianolic acid C, and they were evaluated for xanthine oxidase inhibitory and antioxidant activities. Compounds 5b, 6a, 6e and 6f showed potent xanthine oxidase inhibitory activities with IC50 values ranging from 3.99 to 6.36 μM, which were comparable with that of allopurinol. Lineweaver-Burk plots analysis revealed that the representative derivative 6e could bind to either xanthine oxidase or the xanthine oxidase-xanthine complex, which exhibited a mixed-type competitive mechanism. A DPPH radical scavenging assay showed most of the hydroxyl-functionalized 2-arylbenzo[b]furan derivatives possessed the potent antioxidant activity, which was further validated on LPS-stimulated RAW 264.7 macrophages model. The structure-activity relationships were preliminary analyzed and indicated that the structural skeleton of 2-arylbenzo[b]furan and phenolic hydroxyl groups played an important role in maintaining xanthine oxidase inhibitory effect and antioxidant property for the series of derivatives. Meanwhile, molecular docking studies were performed to further confirm the structure-activity relationships and investigate the proposed binding mechanisms of compounds 5d, 6d and 10d binding to the protein.

  5. Probiotic yogurts manufactured with increased glucose oxidase levels: postacidification, proteolytic patterns, survival of probiotic microorganisms, production of organic acid and aroma compounds.

    PubMed

    Cruz, A G; Castro, W F; Faria, J A F; Lollo, P C B; Amaya-Farfán, J; Freitas, M Q; Rodrigues, D; Oliveira, C A F; Godoy, H T

    2012-05-01

    We investigated the effect of increased glucose oxidase concentration as a technological option to decrease oxidative stress during the processing of probiotic yogurts. Probiotic yogurts were produced with increased concentrations of glucose oxidase (0, 250, 500, 750, or 1,000 mg/kg) and submitted to physicochemical and microbiological analysis at 1, 15, and 30 d of refrigerated storage. Higher concentrations of glucose oxidase (750 and 1,000 mg/kg) and a longer storage time were found to have an influence on the characteristics of the probiotic yogurt, contributing to more extensive postacidification, an increase in the dissolved oxygen level, and higher proteolysis. In addition, increased production of aroma compounds (diacetyl and acetaldehyde) and organic acids (mainly lactic acid) and a decrease in the probiotic bacteria count were reported. The use of glucose oxidase was a feasible option to minimize oxidative stress in probiotic yogurts. However, supplementation with excessive amounts of the enzyme may be ineffective, because insufficient substrate (glucose) is present for its action. Consumer tests should be performed to evaluate changes in the sensory attributes of the probiotic yogurts with increased supplementation of glucose oxidase. In addition, packaging systems with different permeability to oxygen should be evaluated.

  6. Bioseparation of Four Proteins from Euphorbia characias Latex: Amine Oxidase, Peroxidase, Nucleotide Pyrophosphatase/Phosphodiesterase, and Purple Acid Phosphatase

    PubMed Central

    Medda, Rosaria; Pintus, Francesca; Spanò, Delia; Floris, Giovanni

    2011-01-01

    This paper deals with the purification of four proteins from Euphorbia characias latex, a copper amine oxidase, a nucleotide pyrophosphatase/phosphodiesterase, a peroxidase, and a purple acid phosphatase. These proteins, very different in molecular weight, in primary structure, and in the catalyzed reaction, are purified using identical preliminary steps of purification and by chromatographic methods. In particular, the DEAE-cellulose chromatography is used as a useful purification step for all the four enzymes. The purification methods here reported allow to obtain a high purification of all the four proteins with a good yield. This paper will give some thorough suggestions for researchers busy in separation of macromolecules from different sources. PMID:22013530

  7. Salicylic acid inhibits enzymatic browning of fresh-cut Chinese chestnut (Castanea mollissima) by competitively inhibiting polyphenol oxidase.

    PubMed

    Zhou, Dan; Li, Lin; Wu, Yanwen; Fan, Junfeng; Ouyang, Jie

    2015-03-15

    The inhibitory effect and associated mechanisms of salicylic acid (SA) on the browning of fresh-cut Chinese chestnut were investigated. Shelled and sliced chestnuts were immersed in different concentrations of an SA solution, and the browning of the chestnut surface and interior were inhibited. The activities of polyphenol oxidase (PPO) and peroxidase (POD) extracted from chestnuts were measured in the presence and absence of SA. SA at concentrations higher than 0.3g/L delayed chestnut browning by significantly inhibiting the PPO activity (P<0.01), and the POD activity was not significantly affected (P>0.05). The binding and inhibition modes of SA with PPO and POD, determined by AUTODOCK 4.2 and Lineweaver-Burk plots, respectively, established SA as a competitive inhibitor of PPO.

  8. p38 MAPK is involved in human neutrophil chemotaxis induced by L-amino acid oxidase from Calloselasma rhodosthoma.

    PubMed

    Pontes, Adriana S; Setúbal, Sulamita da S; Nery, Neriane Monteiro; da Silva, Francisquinha Souza; da Silva, Silvana D; Fernandes, Carla F C; Stábeli, Rodrigo G; Soares, Andreimar M; Zuliani, Juliana P

    2016-09-01

    The action of LAAO, an L-amino acid oxidase isolated from Calloselasma rhodosthoma snake venom, on isolated human neutrophil function was investigated. Cr-LAAO showed no toxicity on neutrophils. Cr-LAAO in its native form induced the neutrophil chemotaxis, suggesting that its primary structure is essential for stimulation the cell. p38 MAPK and PI3K have a role as signaling pathways of CR-LAAO induced chemotaxis. This toxin also induced the production of hydrogen peroxide and stimulated phagocytosis in neutrophils. Furthermore, Cr-LAAO was able to stimulate neutrophils to release IL-6, IL-8, MPO, LTB4 and PGE2. Together, the data showed that the Cr-LAAO triggers relevant proinflammatory events.

  9. Interfacial electron transfer of glucose oxidase on poly(glutamic acid)-modified glassy carbon electrode and glucose sensing.

    PubMed

    Zhou, Xuechou; Tan, Bingcan; Zheng, Xinyu; Kong, Dexian; Li, Qinglu

    2015-11-15

    The interfacial electron transfer of glucose oxidase (GOx) on a poly(glutamic acid)-modified glassy carbon electrode (PGA/GCE) was investigated. The redox peaks measured for GOx and flavin adenine dinucleotide (FAD) are similar, and the anodic peak of GOx does not increase in the presence of glucose in a mediator-free solution. These indicate that the electroactivity of GOx is not the direct electron transfer (DET) between GOx and PGA/GCE and that the observed electroactivity of GOx is ascribed to free FAD that is released from GOx. However, efficient electron transfer occurred if an appropriate mediator was placed in solution, suggesting that GOx is active. The PGA/GCE-based biosensor showed wide linear response in the range of 0.5-5.5 mM with a low detection limit of 0.12 mM and high sensitivity and selectivity for measuring glucose.

  10. Substrate Orientation and Catalytic Specificity in the Action of Xanthine Oxidase: The Sequential Hydroxylation of Hypoxanthine to Uric Acid

    SciTech Connect

    Cao, Hongnan; Pauff, James M.; Hille, Russ

    2010-11-29

    Xanthine oxidase is a molybdenum-containing enzyme catalyzing the hydroxylation of a sp{sup 2}-hybridized carbon in a broad range of aromatic heterocycles and aldehydes. Crystal structures of the bovine enzyme in complex with the physiological substrate hypoxanthine at 1.8 {angstrom} resolution and the chemotherapeutic agent 6-mercaptopurine at 2.6 {angstrom} resolution have been determined, showing in each case two alternate orientations of substrate in the two active sites of the crystallographic asymmetric unit. One orientation is such that it is expected to yield hydroxylation at C-2 of substrate, yielding xanthine. The other suggests hydroxylation at C-8 to give 6,8-dihydroxypurine, a putative product not previously thought to be generated by the enzyme. Kinetic experiments demonstrate that >98% of hypoxanthine is hydroxylated at C-2 rather than C-8, indicating that the second crystallographically observed orientation is significantly less catalytically effective than the former. Theoretical calculations suggest that enzyme selectivity for the C-2 over C-8 of hypoxanthine is largely due to differences in the intrinsic reactivity of the two sites. For the orientation of hypoxanthine with C-2 proximal to the molybdenum center, the disposition of substrate in the active site is such that Arg880 and Glu802, previous shown to be catalytically important for the conversion of xanthine to uric acid, play similar roles in hydroxylation at C-2 as at C-8. Contrary to the literature, we find that 6,8-dihydroxypurine is effectively converted to uric acid by xanthine oxidase.

  11. Effects of Seselin and Coumarin on Growth, Indoleacetic Acid Oxidase, and Peroxidase, with Special Reference to Cucumber (Cucumis sativa L.) Radicles

    PubMed Central

    Goren, Raphael; Tomer, Eliahu

    1971-01-01

    Seselin, a natural coumarin derivative isolated from citrus roots, inhibited radicle growth in seedlings of cucumber (Cucumis sativa), lettuce (Lactuca sativum), radish (Raphanus sativus), and wheat (Triticum aestivum) grown in the dark. Coumarin similarly inhibited radicle growth of cucumber seedlings. Growth retardation of the cucumber radicles was accompanied by an increased activity of peroxidase and indole-3-acetic acid oxidase. Both compounds antagonized indole-3-acetic acid-induced growth of wheat coleoptiles, whereas coumarin was much less effective than seselin in antagonizing gibberellic acid-induced release of reducing sugars from barley endosperm. It is suggested that seselin plays an important role in the regulation of root growth, and that it is the indole-3-acetic acid oxidase cofactor previously detected in citrus roots. Images PMID:16657614

  12. Implications of terminal oxidase function in regulation of salicylic acid on soybean seedling photosynthetic performance under water stress.

    PubMed

    Tang, Yanping; Sun, Xin; Wen, Tao; Liu, Mingjie; Yang, Mingyan; Chen, Xuefei

    2017-03-01

    The aim of this study is to investigate whether exogenous application of salicylic acid (SA) could modulate the photosynthetic capacity of soybean seedlings in water stress tolerance, and to clarify the potential functions of terminal oxidase (plastid terminal oxidase (PTOX) and alternative oxidase (AOX)) in SA' s regulation on photosynthesis. The effects of SA and water stress on gas exchange, pigment contents, chlorophyll fluorescence, enzymes (guaiacol peroxidase (POD; EC 1.11.1.7), superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11) and NADP-malate dehydrogenase (NADP-MDH; EC1.1.1.82)) activity and transcript levels of PTOX, AOX1, AOX2a, AOX2b were examined in a hydroponic cultivation system. Results indicate that water stress significantly decreased the photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), pigment contents (Chla + b, Chla/b, Car), maximum quantum yield of PSⅡphotochemistry (Fv/Fm), efficiency of excitation capture of open PSⅡcenter (Fv'/Fm'), quantum efficiency of PSⅡphotochemistry (ΦPSⅡ), photochemical quenching (qP), and increased malondialdehyde (MDA) content and the activity of all the enzymes. SA pretreatment led to significant decreases in Ci and MDA content, and increases in Pn, Gs, E, pigment contents, Fv/Fm, Fv'/Fm', ΦPSⅡ, qP, and the activity of all the enzymes. SA treatment and water stress alone significantly up-regulated the expression of PTOX, AOX1 and AOX2b. SA pretreatment further increased the transcript levels of PTOX and AOX2b of soybean seedling under water stress. These results indicate that SA application alleviates the water stress-induced decrease in photosynthesis may mainly through maintaining a lower reactive oxygen species (ROS) level, a greater PSⅡefficiency, and an enhanced alternative respiration and chlororespiration. PTOX and AOX may play important roles in SA-mediated resistance to water stress.

  13. Polyacrylic acid-coated cerium oxide nanoparticles: An oxidase mimic applied for colorimetric assay to organophosphorus pesticides.

    PubMed

    Zhang, Shi-Xiang; Xue, Shi-Fan; Deng, Jingjing; Zhang, Min; Shi, Guoyue; Zhou, Tianshu

    2016-11-15

    It is important and urgent to develop reliable and highly sensitive methods that can provide on-site and rapid detection of extensively used organophosphorus pesticides (OPs) for their neurotoxicity. In this study, we developed a novel colorimetric assay for the detection of OPs based on polyacrylic acid-coated cerium oxide nanoparticles (PAA-CeO2) as an oxidase mimic and OPs as inhibitors to suppress the activity of acetylcholinesterase (AChE). Firstly, highly dispersed PAA-CeO2 was prepared in aqueous solution, which could catalyze the oxidation of TMB to produce a color reaction from colorless to blue. And the enzyme of AChE was used to catalyze the substrate of acetylthiocholine (ATCh) to produce thiocholine (TCh). As a thiol-containing compound with reducibility, TCh can decrease the oxidation of TMB catalyzed by PAA-CeO2. Upon incubated with OPs, the enzymatic activity of AChE was inhibited to produce less TCh, resulting in more TMB catalytically oxidized by PAA-CeO2 to show an increasing blue color. The two representative OPs, dichlorvos and methyl-paraoxon, were tested using our proposed assay. The novel assay showed notable color change in a concentration-dependent manner, and as low as 8.62 ppb dichlorvos and 26.73 ppb methyl-paraoxon can be readily detected. Therefore, taking advantage of such oxidase-like activity of PAA-CeO2, our proposed colorimetric assay can potentially be a screening tool for the precise and rapid evaluation of the neurotoxicity of a wealth of OPs.

  14. Laos: Background and U.S. Relations

    DTIC Science & Technology

    2010-01-04

    hydropower, timber, rubber, and tourism . The Lao economy grew by an estimated 4.5% in 2009, down from 7.5% in 2008, and is expected to grow by 7% in 2010.16...Counting,” Bangkok Post, November 15, 2009; “Thailand to Send More Hmong Refugees Back to Laos,” Thai News Service, September 15, 2009; Maria Patrikainen...and Counting,” Bangkok Post, November 15, 2009; “Thailand to Send More Hmong Refugees Back to Laos,” Thai News Service, September 15, 2009; Maria

  15. Structural characterization of CalO2: A putative orsellinic acid P450 oxidase in the calicheamicin biosynthetic

    SciTech Connect

    McCoy, Jason G.; Johnson, Heather D.; Singh, Shanteri; Bingman, Craig A.; Lei, In-Kyoung; Thorson, Jon S.; Phillips, Jr., George N.

    2009-08-13

    Although bacterial iterative Type I polyketide synthases are now known to participate in the biosynthesis of a small set of diverse natural products, the subsequent downstream modification of the resulting polyketide products remains poorly understood. Toward this goal, we report the X-ray structure determination at 2.5 A resolution and preliminary characterization of the putative orsellenic acid P450 oxidase (CalO2) involved in calicheamicin biosynthesis. These studies represent the first crystal structure for a P450 involved in modifying a bacterial iterative Type I polyketide product and suggest the CalO2-catalyzed step may occur after CalO3-catalyzed iodination and may also require a coenzyme A- (CoA) or acyl carrier protein- (ACP) bound substrate. Docking studies also reveal a putative docking site within CalO2 for the CLM orsellinic acid synthase (CalO5) ACP domain which involves a well-ordered helix along the CalO2 active site cavity that is unique compared with other P450 structures.

  16. Alternative Oxidase Activity in Tobacco Leaf Mitochondria (Dependence on Tricarboxylic Acid Cycle-Mediated Redox Regulation and Pyruvate Activation).

    PubMed

    Vanlerberghe, G. C.; Day, D. A.; Wiskich, J. T.; Vanlerberghe, A. E.; McIntosh, L.

    1995-10-01

    Transgenic Nicotiana tabacum (cv Petit Havana SR1) containing high levels of mitochondrial alternative oxidase (AOX) protein due to the introduction of a sense transgene(s) of Aox1, the nuclear gene encoding AOX, were used to investigate mechanisms regulating AOX activity. After purification of leaf mitochondria, a large proportion of the AOX protein was present as the oxidized (covalently associated and less active) dimer. High AOX activity in these mitochondria was dependent on both reduction of the protein by DTT (to the noncovalently associated and more active dimer) and its subsequent activation by certain [alpha]-keto acids, particularly pyruvate. Reduction of AOX to its more active form could also be mediated by intramitochondrial reducing power generated by the oxidation of certain tricarboxylic acid cycle substrates, most notably isocitrate and malate. Our evidence suggests that NADPH may be specifically required for AOX reduction. All of the above regulatory mechanisms applied to AOX in wild-type mitochondria as well. Transgenic leaves lacking AOX due to the introduction of an Aox1 antisense transgene or multiple sense transgenes were used to investigate the potential physiological significance of the AOX-regulatory mechanisms. Under conditions in which respiratory carbon metabolism is restricted by the capacity of mitochondrial electron transport, feed-forward activation of AOX by mitochondrial reducing power and pyruvate may act to prevent redirection of carbon metabolism, such as to fermentative pathways.

  17. D-Amino acid oxidase-induced oxidative stress, 3-bromopyruvate and citrate inhibit angiogenesis, exhibiting potent anticancer effects.

    PubMed

    El Sayed, S M; El-Magd, R M Abou; Shishido, Y; Yorita, K; Chung, S P; Tran, D H; Sakai, T; Watanabe, H; Kagami, S; Fukui, K

    2012-10-01

    Angiogenesis is critical for cancer growth and metastasis. Steps of angiogenesis are energy consuming, while vascular endothelial cells are highly glycolytic. Glioblastoma multiforme (GBM) is a highly vascular tumor and this enhances its aggressiveness. D-amino acid oxidase (DAO) is a promising therapeutic protein that induces oxidative stress upon acting on its substrates. Oxidative stress-energy depletion (OSED) therapy was recently reported (El Sayed et al., Cancer Gene Ther, 19, 1-18, 2012). OSED combines DAO-induced oxidative stress with energy depletion caused by glycolytic inhibitors such as 3-bromopyruvate (3BP), a hexokinase II inhibitor that depleted ATP in cancer cells and induced production of hydrogen peroxide. 3BP disturbs the Warburg effect and antagonizes effects of lactate and pyruvate (El Sayed et al., J Bioenerg Biomembr, 44, 61-79, 2012). Citrate is a natural organic acid capable of inhibiting glycolysis by targeting phosphofructokinase. Here, we report that DAO, 3BP and citrate significantly inhibited angiogenesis, decreased the number of vascular branching points and shortened the length of vascular tubules. OSED delayed the growth of C6/DAO glioma cells. 3BP combined with citrate delayed the growth of C6 glioma cells and decreased significantly the number and size of C6 glioma colonies in soft agar. Human GBM cells (U373MG) were resistant to chemotherapy e.g. cisplatin and cytosine arabinoside, while 3BP was effective in decreasing the viability and disturbing the morphology of U373MG cells.

  18. The conformational state of polyphenol oxidase from field bean (Dolichos lablab) upon SDS and acid-pH activation.

    PubMed

    Kanade, Santosh R; Paul, Beena; Rao, A G Appu; Gowda, Lalitha R

    2006-05-01

    Field bean (Dolichos lablab) contains a single isoform of PPO (polyphenol oxidase)--a type III copper protein that catalyses the o-hydroxylation of monophenols and oxidation of o-diphenols using molecular oxygen--and is a homotetramer with a molecular mass of 120 kDa. The enzyme is activated manyfold either in the presence of the anionic detergent SDS below its critical micellar concentration or on exposure to acid-pH. The enhancement of kcat upon activation is accompanied by a marked shift in the pH optimum for the oxidation of t-butyl catechol from 4.5 to 6.0, an increased sensitivity to tropolone, altered susceptibility to proteolytic degradation and decreased thermostability. The Stokes radius of the native enzyme is found to increase from 49.1+/-2 to 75.9+/-0.6 A (1 A=0.1 nm). The activation by SDS and acid-pH results in a localized conformational change that is anchored around the catalytic site of PPO that alters the microenvironment of an essential glutamic residue. Chemical modification of field bean and sweet potato PPO with 1-ethyl-3-(3-dimethylaminopropyl)carbodi-imide followed by kinetic analysis leads to the conclusion that both the enzymes possess a core carboxylate essential to activity. This enhanced catalytic efficiency of PPO, considered as an inducible defence oxidative enzyme, is vital to the physiological defence strategy adapted by plants to insect herbivory and pathogen attack.

  19. A facile and effective immobilization of glucose oxidase on tannic acid modified CoFe2O4 magnetic nanoparticles.

    PubMed

    Altun, Seher; Çakıroğlu, Bekir; Özacar, Münteha; Özacar, Mahmut

    2015-12-01

    This article presents a study of glucose oxidase (GOx) immobilization by employing tannic acid (TA) modified-CoFe2O4 (CFO) magnetic nanoparticles which demonstrates novel aspect for enzyme immobilization. By using the strong protein and tannic acid binding, GOx immobilization was carried out via physical adsorption in a simpler way compared with the other immobilization methods which require various chemicals and complicated procedures which is difficult, expensive, time-consuming, and destructive to the enzyme structure. CFO was synthesized by hydrothermal synthesis and modified with TA to immobilize GOx. The immobilized GOx demonstrated maximum catalytic activity at pH 6.5 and 45 °C. The samples were characterized by vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), zeta potential, and fourier transform infrared spectroscopy (FTIR), all of which confirm the surface modification of CFO and GOx immobilization. Also, field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) were performed to demonstrate the surface morphology and chemical structure of samples. According to the Lineweaver-Burk plot, GOx possessed lower affinity to glucose after immobilization, and the Michelis-Menten constant (KM) of immobilized and free GOx were found to be 50.05 mM and 28.00 mM, respectively. The immobilized GOx showed excellent reusability, and even after 8 consecutive activity assay runs, the immobilized GOx maintained ca. 60% of its initial activity.

  20. Changes in D-aspartic acid and D-glutamic acid levels in the tissues and physiological fluids of mice with various D-aspartate oxidase activities.

    PubMed

    Han, Hai; Miyoshi, Yurika; Koga, Reiko; Mita, Masashi; Konno, Ryuichi; Hamase, Kenji

    2015-12-10

    D-Aspartic acid (D-Asp) and D-glutamic acid (D-Glu) are currently paid attention as modulators of neuronal transmission and hormonal secretion. These two D-amino acids are metabolized only by D-aspartate oxidase (DDO) in mammals. Therefore, in order to design and develop new drugs controlling the D-Asp and D-Glu amounts via regulation of the DDO activities, changes in these acidic D-amino acid amounts in various tissues are expected to be clarified in model animals having various DDO activities. In the present study, the amounts of Asp and Glu enantiomers in 6 brain tissues, 11 peripheral tissues and 2 physiological fluids of DDO(+/+), DDO(+/-) and DDO(-/-) mice were determined using a sensitive and selective two-dimensional HPLC system. As a result, the amounts of D-Asp were drastically increased with the decrease in the DDO activity in all the tested tissues and physiological fluids. On the other hand, the amounts of D-Glu were almost the same among the 3 strains of mice. The present results are useful for designing new drug candidates, such as DDO inhibitors, and further studies are expected.

  1. Synthesis and characterization of microparticles based on poly-methacrylic acid with glucose oxidase for biosensor applications.

    PubMed

    Hervás Pérez, J P; López-Ruiz, B; López-Cabarcos, E

    2016-01-01

    In the line of the applicability of biocompatible monomers pH and temperature dependent, we assayed poly-methacrylic acid (p-MAA) microparticles as immobilization system in the design of enzymatic biosensors. Glucose oxidase was used as enzyme model for the study of microparticles as immobilization matrices and as biological material in the performance of glucose biosensors. The enzyme immobilization method was optimized by investigating the influence of monomer concentration and cross-linker content (N',N'-methylenebisacrylamide), used in the preparation of the microparticles in the response of the biosensors. The kinetics of the polymerization and the effects of the temperature were studied, also the conversion of the polymerization was determinates by a weight method. The structure of the obtained p-MAA microparticles were studied through scanning electron microscopy (SEM) and differential scanning microscopy (DSC). The particle size measurements were performed with a Galai-Cis 1 particle analyzer system. Furthermore, the influence of the swelling behavior of hydrogel matrix as a function of pH and temperature were studied. Analytical properties such as sensitivity, linear range, response time and detection limit were studied for the glucose biosensors. The sensitivity for glucose detection obtained with poly-methacrylic acid (p-MAA) microparticles was 11.98mAM(-1)cm(-2) and 10μM of detection limit. A Nafion® layer was used to eliminate common interferents of the human serum such as uric and ascorbic acids. The biosensors were used to determine glucose in human serum samples with satisfactory results. When stored in a frozen phosphate buffer solution (pH 6.0) at -4°C, the useful lifetime of all biosensors was at least 550 days.

  2. D-amino acid oxidase gene therapy sensitizes glioma cells to the antiglycolytic effect of 3-bromopyruvate.

    PubMed

    El Sayed, S M; Abou El-Magd, R M; Shishido, Y; Chung, S P; Sakai, T; Watanabe, H; Kagami, S; Fukui, K

    2012-01-01

    Glioma tumors are refractory to conventional treatment. Glioblastoma multiforme is the most aggressive type of primary brain tumors in humans. In this study, we introduce oxidative stress-energy depletion (OSED) therapy as a new suggested treatment for glioblastoma. OSED utilizes D-amino acid oxidase (DAO), which is a promising therapeutic protein that induces oxidative stress and apoptosis through generating hydrogen peroxide (H2O2). OSED combines DAO with 3-bromopyruvate (3BP), a hexokinase II (HK II) inhibitor that interferes with Warburg effect, a metabolic alteration of most tumor cells that is characterized by enhanced aerobic glycolysis. Our data revealed that 3BP induced depletion of energetic capabilities of glioma cells. 3BP induced H2O2 production as a novel mechanism of its action. C6 glioma transfected with DAO and treated with D-serine together with 3BP-sensitized glioma cells to 3BP and decreased markedly proliferation, clonogenic power and viability in a three-dimensional tumor model with lesser effect on normal astrocytes. DAO gene therapy using atelocollagen as an in vivo transfection agent proved effective in a glioma tumor model in Sprague-Dawley (SD) rats, especially after combination with 3BP. OSED treatment was safe and tolerable in SD rats. OSED therapy may be a promising therapeutic modality for glioma.

  3. Factors influencing diamine oxidase activity and γ-aminobutyric acid content of fava bean (Vicia faba L.) during germination.

    PubMed

    Yang, Runqiang; Chen, Hui; Gu, Zhenxin

    2011-11-09

    Factors (germination time, spectra, temperature, pH, and chemical inhibitors) influencing diamine oxidase (DAO, EC 1.4.3.6) activity and γ-aminobutyric acid (GABA) content of fava bean (Vicia faba L.) during germination were investigated in this study. DAO activity significantly increased in germinating seeds but varied with different organs. The enzyme activity was higher in shoot than that in cotyledon, hypocotyl, and radicle. When seeds were germinated in the dark, DAO activity was 2.35-, 2.00-, 2.36-, 4.40-, and 1.67-fold of that under white, red, blue, green, and yellow spectra, respectively. The optimum germination temperature and pH value for increasing DAO activity were 30 °C and 3.0, respectively. The DAO activity was inhibited significantly by aminoguanidine and sodium ethylenediamine tetracetate, while it was activated by CuCl(2) and CaCl(2). Germinating at an appropriate temperature and pH, 30% of GABA formation was supplied by DAO. Calcium was related to the regulation of DAO activity and GABA accumulation.

  4. Mechanism of the cytotoxic effect of l-amino acid oxidase isolated from Bothrops alternatus snake venom.

    PubMed

    Ribeiro, Patrícia H; Zuliani, Juliana P; Fernandes, Carla F C; Calderon, Leonardo A; Stábeli, Rodrigo G; Nomizo, Auro; Soares, Andreimar M

    2016-11-01

    BaltLAAO-I, an L-amino acid oxidase isolated from Bothrops alternatus, is a glycoprotein enzyme with a pI-5.3, 15% sugar and a related molecular mass of 66,000Da in its monomeric form, and 123,000Da in its dimeric form. The objective of this study is to describe the cytotoxicity activity induced by BaltLAAO-I isolated from Bothrops alternatus venom and its possible mechanism of action on tumor cells. Our results clearly depict that BaltLAAO-I has a strong selective cytotoxic activity on tumor cell lines (JURKAT, SK-BR-3 and B16F10). On the other hand, the results show low cytotoxicity on human peripheral blood mononuclear cells. Furthermore, our findings demonstrate that BaltLAAO-I induces the apoptosis of tumor cell lines through a cytotoxic activity exerted by a generation of reactive oxygen intermediates. All in all, the data indicate that LAAOs exert a selective cytotoxic role on tumor cells, demonstrating a great potential for future use in clinical therapy.

  5. Association-dissociation of the flavoprotein hog kidney D-amino acid oxidase. Determination of the monomer-dimer equilibrium constant and the energetics of subunit association.

    PubMed

    Horiike, K; Shiga, K; Nishina, Y; Isomoto, A; Yamano, T

    1977-11-01

    The enzyme concentration dependence of spectrophotometric titrations of hog kidney D-amino acid oxidase [EC 1.4.3.3] with p-aminobenzoate was studied. The monomer-dimer equilibrium constant of the oxidized holoenzyme at 25 degrees C was estimated to be 7 X 10(5)M-1 at pH 7.5 and 4X 10(6)M-1 at pH 8.3. The energetics of subunit association are discussed.

  6. Interplay between microbial d-amino acids and host d-amino acid oxidase modifies murine mucosal defence and gut microbiota.

    PubMed

    Sasabe, Jumpei; Miyoshi, Yurika; Rakoff-Nahoum, Seth; Zhang, Ting; Mita, Masashi; Davis, Brigid M; Hamase, Kenji; Waldor, Matthew K

    2016-07-25

    L-Amino acids are the building blocks for proteins synthesized in ribosomes in all kingdoms of life, but d-amino acids (d-aa) have important non-ribosome-based functions(1). Mammals synthesize d-Ser and d-Asp, primarily in the central nervous system, where d-Ser is critical for neurotransmission(2). Bacteria synthesize a largely distinct set of d-aa, which become integral components of the cell wall and are also released as free d-aa(3,4). However, the impact of free microbial d-aa on host physiology at the host-microbial interface has not been explored. Here, we show that the mouse intestine is rich in free d-aa that are derived from the microbiota. Furthermore, the microbiota induces production of d-amino acid oxidase (DAO) by intestinal epithelial cells, including goblet cells, which secrete the enzyme into the lumen. Oxidative deamination of intestinal d-aa by DAO, which yields the antimicrobial product H2O2, protects the mucosal surface in the small intestine from the cholera pathogen. DAO also modifies the composition of the microbiota and is associated with microbial induction of intestinal sIgA. Collectively, these results identify d-aa and DAO as previously unrecognized mediators of microbe-host interplay and homeostasis on the epithelial surface of the small intestine.

  7. Human spermatozoa possess an IL4I1 l-amino acid oxidase with a potential role in sperm function.

    PubMed

    Houston, B; Curry, B; Aitken, R J

    2015-06-01

    Reactive oxygen species (ROS) are known to play an important role in the regulation of human sperm function. In this study, we demonstrate for the first time that human spermatozoa possess interleukin-induced gene 1 (IL4I1), an l-amino acid oxidase (LAAO) which is capable of generating ROS on exposure to aromatic amino acids in the presence of oxygen. The preferred substrates were found to be phenylalanine and tryptophan while the enzyme was located in the acrosomal region and midpiece of these cells. In contrast to equine and bovine spermatozoa, enzyme activity was lost as soon as the spermatozoa became non-viable. On a cell-to-cell basis human spermatozoa were also shown to generate lower levels of hydrogen peroxide than their equine counterparts on exposure to phenylalanine. Stimulation of LAAO activity resulted in the induction of several hallmarks of capacitation including tyrosine phosphorylation of the sperm flagellum and concomitant activation of phospho-SRC expression. In addition, stimulation of LAAO resulted in an increase in the levels of acrosomal exocytosis in both the presence and absence of progesterone stimulation, via mechanisms that could be significantly reversed by the presence of catalase. As is often the case with free radical-mediated phenomena, prolonged exposure of human spermatozoa to phenylalanine resulted in the stimulation of apoptosis as indicated by significant increases in mitochondrial superoxide generation and the activation of intracellular caspases. These results confirm the existence of an LAAO in human spermatozoa with a potential role in driving the redox regulation of sperm capacitation and acrosomal exocytosis.

  8. Different Lineage of Porcine Deltacoronavirus in Thailand, Vietnam and Lao PDR in 2015.

    PubMed

    Saeng-Chuto, K; Lorsirigool, A; Temeeyasen, G; Vui, D T; Stott, C J; Madapong, A; Tripipat, T; Wegner, M; Intrakamhaeng, M; Chongcharoen, W; Tantituvanont, A; Kaewprommal, P; Piriyapongsa, J; Nilubol, D

    2017-02-01

    Porcine deltacoronavirus (PDCoV) was detected by RT-PCR in 12 of 97 (12.4%) intestinal samples collected during 2015 from piglets with diarrhoea in Thailand, Vietnam and Lao PDR. Spike, membrane and nucleocapsid genes were characterized, and phylogenetic analyses demonstrated that PDCoV isolates from Thai and Lao PDR form a novel cluster, separated from US and China isolates, but relatively were more closely related to China PDCoV than US isolates. Vietnam PDCoVs, however, were grouped together with US PDCoV. The analyses of amino acid changes suggested that they were from different lineage.

  9. Mechanism-based pharmacokinetic-pharmacodynamic modeling of salvianolic acid A effects on plasma xanthine oxidase activity and uric acid levels in acute myocardial infarction rats.

    PubMed

    Wang, Haidong; Li, Xi; Zhang, Wenting; Liu, Yao; Wang, Shijun; Liu, Xiaoquan; He, Hua

    2017-03-01

    1. Salvianolic acid A (SalA) was found to attenuate plasma uric acid (UA) concentration and xanthine oxidase (XO) activity in acute myocardial infraction (AMI) rats, which was characterized with developed mechanism-based pharmacokinetic-pharmacodynamic (PK-PD) model. 2. AMI was induced in rats by coronary artery ligation. Surviving AMI rats received a single intravenous dose of 5 mg/kg of SalA and normal saline. The plasma SalA concentrations were determined by HPLC-MS/MS method. The plasma UA concentrations were determined by HPLC method and plasma XO activity were measured spectrophotometrically. An integrated mathematical model characterized the relationship between plasma UA and SalA. 3. Pharmacokinetics was described using two-compartment model for SalA with linear metabolic process. In post-AMI rats, XO activity and UA concentrations were increased, while SalA dosing palliated this increase. These effects were well captured by using two series of transduction models, simulating the delay of inhibition on XO driven by SalA and UA elevation resulted from the multiple factors, respectively. 4. The effect was well described by the developed PK-PD model, indicating that SalA can exert cardiovascular protective effects by decreasing elevated plasma UA levels induced by AMI.

  10. Health Information in Laotian (Lao): MedlinePlus

    MedlinePlus

    ... Coping with Disasters Tips for Coping with the Oil Spill Disaster -- Managing Your Stress - English Lao (Laotian) PDF ... Tips for Dealing with Grief Due to the Oil Spill Disaster - English Lao (Laotian) PDF Substance Abuse and ...

  11. Retinoic acid modulation of thyroid dual oxidase activity in rats and its impact on thyroid iodine organification.

    PubMed

    Mühlbauer, Mônica; da Silva, Alba Cenélia Matos; Marassi, Michelle Porto; Lourenço, Alexandre Lopes; Ferreira, Andrea Claudia Freitas; de Carvalho, Denise Pires

    2010-06-01

    The sodium-iodide symporter (NIS) mediates iodide uptake into the thyrocytes, which is important for the diagnosis and therapy of thyroid disorders. Decreased ability to uptake iodide in thyroid carcinomas reduces the efficacy of radioiodine therapy, and retinoic acid (RA) treatment reinduces iodide uptake. The effectiveness of treatment depends not only on iodide uptake but also on the ability of thyrocytes to organify iodine, which is catalyzed by thyroperoxidase (TPO) in the presence of H(2)O(2). Our goal was to determine the influence of RA on thyroid iodide uptake, iodine organification, and TPO and dual oxidase (DuOx) activities. Normal rats were treated with all-trans-RA or 13-cis-RA (100 or 1500 microg/100 g body weight (b.w.), s.c.) for 14 and 28 days. The 2 h thyroid radioiodine content significantly decreased in rats treated with all-trans-RA (100 microg/100 g b.w.) for 14 days. In this group, NIS function and TPO activity were unchanged, whereas DuOx activity was significantly decreased, which might have contributed to the decrease in iodine organification. Both doses of 13-cis-RA for 28 days increased the 15 min thyroid radioiodine uptake, while the 2 h radioiodide uptake increased only in rats treated with the highest dose of 13-cis-RA. While TPO activity did not change, H(2)O(2) generation was increased in this group, and serum thyroxine levels were normal. Since radioiodine half-life in the thyroid gland is important for treatment efficacy, our results highlight the importance of correctly choosing the RA isomer, the time and the dose of treatment, in order to improve the efficacy of radioiodine therapy.

  12. Retinal NMDA receptor function and expression are altered in a mouse lacking d-amino acid oxidase

    PubMed Central

    Morgans, Catherine W.; Tekmen, Merve; Sullivan, Steven J.; Esguerra, Manuel; Konno, Ryuichi; Miller, Robert F.

    2013-01-01

    d-serine is present in the vertebrate retina and serves as a coagonist for the N-methyl-d-aspartate (NMDA) receptors of ganglion cells. Although the enzyme d-amino acid oxidase (DAO) has been implicated as a pathway for d-serine degradation, its role in the retina has not been established. In this study, we investigated the role of DAO in regulating d-serine levels using a mutant mouse line deficient in DAO (ddY/DAO−) and compared these results with their wild-type counterparts (ddY/DAO+). Our results show that DAO is functionally present in the mouse retina and normally serves to reduce the background levels of d-serine. The enzymatic activity of DAO was restricted to the inner plexiform layer as determined by histochemical analysis. Using capillary electrophoresis, we showed that mutant mice had much higher levels of d-serine. Whole cell recordings from identified retinal ganglion cells demonstrated that DAO-deficient animals had light-evoked synaptic activity strongly biased toward a high NMDA-to-AMPA receptor ratio. In contrast, recordings from wild-type ganglion cells showed a more balanced ratio between the two receptor subclasses. Immunostaining for AMPA and NMDA receptors was carried out to compare the two receptor ratios by quantitative immunofluorescence. These studies revealed that the mutant mouse had a significantly higher representation of NMDA receptors compared with the wild-type controls. We conclude that 1) DAO is an important regulatory enzyme and normally functions to reduce d-serine levels in the retina, and 2) d-serine levels play a role in the expression of NMDA receptors and the NMDA-to-AMPA receptor ratio. PMID:24068757

  13. Molecular mechanism of cell death induced by king cobra (Ophiophagus hannah) venom l-amino acid oxidase.

    PubMed

    Fung, Shin Yee; Lee, Mui Li; Tan, Nget Hong

    2015-03-01

    Snake venom LAAOs have been reported to exhibit a wide range of pharmacological activities, including cytotoxic, edema-inducing, platelet aggregation-inducing/platelet aggregation-inhibiting, bactericidal and antiviral activities. A heat-stable form of l-amino acid oxidase isolated from king cobra (Ophiophagus hannah) venom (OH-LAAO) has been shown to exhibit very potent cytotoxicity against human tumorigenic cells but not in their non-tumorigenic counterparts, and the cytotoxicity was due to the apoptosis-inducing effect of the enzyme. In this work, the molecular mechanism of cell death induced by OH-LAAO was investigated. The enzyme exerts its apoptosis-inducing effect presumably via both intrinsic and extrinsic pathways as suggested by the increase in caspase-8 and -9 activities. Oligonucleotide microarray analysis showed that the expression of a total of 178 genes was significantly altered as a result of oxidative stress induced by the hydrogen peroxide generated by the enzyme. Of the 178 genes, at least 27 genes are involved in apoptosis and cell death. These alterations of gene expression was presumably caused by the direct cytotoxic effect of H2O2 generated during the enzymatic reaction, as well as the non-specific oxidative modifications of signaling molecules that eventually lead to apoptosis and cell death. The very substantial up-regulation of cytochrome P450 genes may also contribute to the potent cytotoxic action of OH-LAAO by producing excessive reactive oxygen species (ROS). In conclusion, the potent apoptosis inducing activity of OH-LAAO was likely due to the direct cytotoxic effect of H2O2 generated during the enzymatic reaction, as well as the non-specific oxidation of signalling molecules.

  14. Haplotypes of the D-Amino Acid Oxidase Gene Are Significantly Associated with Schizophrenia and Its Neurocognitive Deficits

    PubMed Central

    Hwu, Hai-Gwo; Fann, Cathy Shen-Jang; Yang, Ueng-Cheng; Yang, Wei-Chih; Hsu, Pei-Chun; Chang, Chien-Ching; Wen, Chun-Chiang; Tsai-Wu, Jyy-Jih; Hwang, Tzung-Jeng; Hsieh, Ming H.; Liu, Chen-Chung; Chien, Yi-Ling; Fang, Chiu-Ping; Faraone, Stephen V.; Tsuang, Ming T.; Chen, Wei J.; Liu, Chih-Min

    2016-01-01

    D-amino acid oxidase (DAO) has been reported to be associated with schizophrenia. This study aimed to search for genetic variants associated with this gene. The genomic regions of all exons, highly conserved regions of introns, and promoters of this gene were sequenced. Potentially meaningful single-nucleotide polymorphisms (SNPs) obtained from direct sequencing were selected for genotyping in 600 controls and 912 patients with schizophrenia and in a replicated sample consisting of 388 patients with schizophrenia. Genetic associations were examined using single-locus and haplotype association analyses. In single-locus analyses, the frequency of the C allele of a novel SNP rs55944529 located at intron 8 was found to be significantly higher in the original large patient sample (p = 0.016). This allele was associated with a higher level of DAO mRNA expression in the Epstein-Barr virus-transformed lymphocytes. The haplotype distribution of a haplotype block composed of rs11114083-rs2070586-rs2070587-rs55944529 across intron 1 and intron 8 was significantly different between the patients and controls and the haplotype frequencies of AAGC were significantly higher in patients, in both the original (corrected p < 0.0001) and replicated samples (corrected p = 0.0003). The CGTC haplotype was specifically associated with the subgroup with deficits in sustained attention and executive function and the AAGC haplotype was associated with the subgroup without such deficits. The DAO gene was a susceptibility gene for schizophrenia and the genomic region between intron 1 and intron 8 may harbor functional genetic variants, which may influence the mRNA expression of DAO and neurocognitive functions in schizophrenia. PMID:26986737

  15. Evidence that d-cysteine protects mice from gastric damage via hydrogen sulfide produced by d-amino acid oxidase.

    PubMed

    Souza, Luan Kelves M; Araújo, Thiago S L; Sousa, Nayara A; Sousa, Francisca Beatriz M; Nogueira, Kerolayne M; Nicolau, Lucas A D; Medeiros, Jand Venes R

    2017-04-01

    Hydrogen sulfide (H2S) is a signaling molecule in the gastrointestinal tract. H2S production can derive from d-cysteine via various pathways, thus pointing to a new therapeutic approach: delivery of H2S to specific tissues. This study was designed to evaluate the concentration and effects of H2S (generated by d-amino acid oxidase [DAO] from d-cysteine) in the gastric mucosa and the protective effects against ethanol-induced lesions in mice. Mice were treated with l-cysteine or d-cysteine (100 mg/kg per os). Other groups received oral l-propargylglycine (cystathionine γ-lyase inhibitor, 100 mg/kg) or indole-2-carboxylate (DAO inhibitor), and 30 min later, received d- or l-cysteine. After 30 min, 50% ethanol (2.5 mL/kg, per os) was administered. After 1 h, the mice were euthanized and their stomachs excised and analyzed. Pretreatment with either l-cysteine or d-cysteine significantly reduced ethanol-induced lesions. Pretreatment of d-cysteine- or l-cysteine-treated groups with indole-2-carboxylate reversed the gastroprotective effects of d-cysteine but not l-cysteine. Histological analysis revealed that pretreatment with d-cysteine decreased hemorrhagic damage, edema, and the loss of the epithelium, whereas the administration of indole-2-carboxylate reversed these effects. d-Cysteine also reduced malondialdehyde levels but maintained the levels of reduced glutathione. Furthermore, pretreatment with d-cysteine increased the synthesis of H2S. Thus, an H2S-generating pathway (involving d-cysteine and DAO) is present in the gastric mucosa and protects this tissue from ethanol-induced damage by decreasing direct oxidative damage.

  16. On the reaction of D-amino acid oxidase with dioxygen: O2 diffusion pathways and enhancement of reactivity.

    PubMed

    Rosini, Elena; Molla, Gianluca; Ghisla, Sandro; Pollegioni, Loredano

    2011-02-01

    Evidence is accumulating that oxygen access in proteins is guided and controlled. We also have recently described channels that might allow access of oxygen to pockets at the active site of the flavoprotein D-amino acid oxidase (DAAO) that have a high affinity for dioxygen and are in close proximity to the flavin. With the goal of enhancing the reactivity of DAAO with oxygen, we have performed site-saturation mutagenesis at three positions that flank the putative oxygen channels and high-affinity sites. The most interesting variants at positions 50, 201 and 225 were identified by a screening procedure at low oxygen concentration. The biochemical properties of these variants have been studied and compared with those of wild-type DAAO, with emphasis on the reactivity of the reduced enzyme species with dioxygen. The substitutions at positions 50 and 225 do not enhance this reaction, but mainly affect the protein conformation and stability. However, the T201L variant shows an up to a threefold increase in the rate constant for reaction of O(2) with reduced flavin, together with a fivefold decrease in the K(m) for dioxygen. This effect was not observed when a valine is located at position 201, and is thus attributed to a specific alteration in the micro-environment of one high-affinity site for dioxygen (site B) close to the flavin that plays an important role in the storage of oxygen. The increase in O(2) reactivity observed for T201L DAAO is of great interest for designing new flavoenzymes for biotechnological applications.

  17. Pear ACO genes encoding putative 1-aminocyclopropane-1-carboxylate oxidase homologs are functionally expressed during fruit ripening and involved in response to salicylic acid.

    PubMed

    Shi, Hai-Yan; Zhang, Yu-Xing

    2012-10-01

    1-Aminocyclopropane-1-carboxylate (ACC) oxidase catalyzes the final reaction of the ethylene biosynthetic pathway, converting ACC into ethylene. Past studies have shown a possible link between ACC oxidase and salicylic acid during fruit ripening in pear, but the relationship has received no more than modest study at the gene expression level. In this study, two cDNA clones encoding putative ACC oxidase, PpACO1 and PpACO2, were isolated from a cDNA library constructed by our own laboratory and produced using mRNA from mesocarp of pear (Pyrus pyrifolia Nakai. cv.Whangkeumbae). One cDNA clone, designated PpACO1 (GenBank accession No. JN807390), comprised an open reading frame of 945 bp encoding a protein of 314 amino acids. The other cDNA, designated PpACO2 (GenBank accession No. JN807392), encodes a protein with 322 amino acids that shares high similarity with the known plant ACOs. Using PCR amplification techniques, two genomic clones corresponding to PpACO1 and PpACO2 were isolated and shown to contain independently three introns with typical GT/AG boundaries defining the splice junctions. The PpACO1 gene product shared 99 % identity with an ACC oxidase from pear (Pyrus × bretschneideri Rehd.cv.Yali), and phylogenetic analyses clearly placed the gene product in the ACC oxidase cluster of the pear 2-oxoglutarate-dependent dioxygenase superfamily tree. Quantitative RT-PCR analysis indicated that the two PpACO genes are differentially expressed in pear tissues. PpACO1 and PpACO2 were predominantly expressed in fruit. The transcripts of PpACO1 were accumulated at relatively low levels in early fruit, but strongly high levels in fruit ripening and senescence stages, while the transcripts of PpACO2 were accumulated at higher levels in early fruit and much lower levels with further fruit cell development than the transcripts of PpACO1. In addition, PpACO1 gene was down-regulated in fruit by salicylic acid (SA). Nevertheless, PpACO2 gene was dramatically up-regulated in

  18. Modulating NMDA Receptor Function with D-Amino Acid Oxidase Inhibitors: Understanding Functional Activity in PCP-Treated Mouse Model

    PubMed Central

    Sershen, Henry; Hashim, Audrey; Dunlop, David S.; Suckow, Raymond F.; Cooper, Tom B.; Javitt, Daniel C.

    2016-01-01

    Deficits in N-methyl-D-aspartate receptor (NMDAR) function are increasingly linked to persistent negative symptoms and cognitive deficits in schizophrenia. Accordingly, clinical studies have been targeting the modulatory site of the NMDA receptor, based on the decreased function of NMDA receptor, to see whether increasing NMDA function can potentially help treat the negative and cognitive deficits seen in the disease. Glycine and D-serine are endogenous ligands to the NMDA modulatory site, but since high doses are needed to affect brain levels, related compounds are being developed, for example glycine transport (GlyT) inhibitors to potentially elevate brain glycine or targeting enzymes, such as D-amino acid oxidase (DAAO) to slow the breakdown and increase the brain level of D-serine. In the present study we further evaluated the effect of DAAO inhibitors 5-chloro-benzo[d]isoxazol-3-ol (CBIO) and sodium benzoate (NaB) in a phencyclidine (PCP) rodent mouse model to see if the inhibitors affect PCP-induced locomotor activity, alter brain D-serine level, and thereby potentially enhance D-serine responses. D-Serine dose-dependently reduced the PCP-induced locomotor activity at doses above 1000 mg/kg. Acute CBIO (30 mg/kg) did not affect PCP-induced locomotor activity, but appeared to reduce locomotor activity when given with D-serine (600 mg/kg); a dose that by itself did not have an effect. However, the effect was also present when the vehicle (Trappsol®) was tested with D-serine, suggesting that the reduction in locomotor activity was not related to DAAO inhibition, but possibly reflected enhanced bioavailability of D-serine across the blood brain barrier related to the vehicle. With this acute dose of CBIO, D-serine level in brain and plasma were not increased. Another weaker DAAO inhibitor sodium benzoate (NaB) (400 mg/kg), and NaB plus D-serine also significantly reduced PCP-induced locomotor activity, but without affecting plasma or brain D-serine level

  19. Causes of Fever in Rural Southern Laos

    PubMed Central

    Mayxay, Mayfong; Sengvilaipaseuth, Onanong; Chanthongthip, Anisone; Dubot-Pérès, Audrey; Rolain, Jean-Marc; Parola, Philippe; Craig, Scott B.; Tulsiani, Suhella; Burns, Mary-Anne; Khanthavong, Maniphone; Keola, Siamphay; Pongvongsa, Tiengkham; Raoult, Didier; Dittrich, Sabine; Newton, Paul N.

    2015-01-01

    The etiology of fever in rural Lao People's Democratic Republic (Laos) has remained obscure until recently owing to the lack of laboratory facilities. We conducted a study to determine the causes of fever among 229 patients without malaria in Savannakhet Province, southern Laos; 52% had evidence of at least one diagnosis (45% with single and 7% with apparent multiple infections). Among patients with only one diagnosis, dengue (30.1%) was the most common, followed by leptospirosis (7.0%), Japanese encephalitis virus infection (3.5%), scrub typhus (2.6%), spotted fever group infection (0.9%), unspecified flavivirus infection (0.9%), and murine typhus (0.4%). We discuss the empirical treatment of fever in relation to these findings. PMID:26149859

  20. Causes of Fever in Rural Southern Laos.

    PubMed

    Mayxay, Mayfong; Sengvilaipaseuth, Onanong; Chanthongthip, Anisone; Dubot-Pérès, Audrey; Rolain, Jean-Marc; Parola, Philippe; Craig, Scott B; Tulsiani, Suhella; Burns, Mary-Anne; Khanthavong, Maniphone; Keola, Siamphay; Pongvongsa, Tiengkham; Raoult, Didier; Dittrich, Sabine; Newton, Paul N

    2015-09-01

    The etiology of fever in rural Lao People's Democratic Republic (Laos) has remained obscure until recently owing to the lack of laboratory facilities. We conducted a study to determine the causes of fever among 229 patients without malaria in Savannakhet Province, southern Laos; 52% had evidence of at least one diagnosis (45% with single and 7% with apparent multiple infections). Among patients with only one diagnosis, dengue (30.1%) was the most common, followed by leptospirosis (7.0%), Japanese encephalitis virus infection (3.5%), scrub typhus (2.6%), spotted fever group infection (0.9%), unspecified flavivirus infection (0.9%), and murine typhus (0.4%). We discuss the empirical treatment of fever in relation to these findings.

  1. High prevalence and molecular characteristics of multidrug-resistant Salmonella in pigs, pork and humans in Thailand and Laos provinces.

    PubMed

    Sinwat, Nuananong; Angkittitrakul, Sunpetch; Coulson, Kari F; Pilapil, Flor Marie Immanuelle R; Meunsene, Dethaloun; Chuanchuen, Rungtip

    2016-10-01

    This study aimed to examine occurrence and antimicrobial resistance characteristics of Salmonella from pigs, pork and humans in Thailand and Laos provinces. The samples were collected from pigs, carcasses and workers in slaughterhouses, retail pork and butchers in fresh markets and patients in hospitals in Thailand (n=729) and Laos (n=458). A total of 295 of 729 samples (34.6 %) collected in Thailand and 253 of 458 (47.4 %) samples collected in Laos were positive for Salmonella. A total of 548 Salmonella isolates from Thailand (n=295) and Laos (n=253) were further analysed. Serovar Typhimurium was the most common serotype in Thai (34 %) and Laos (20.6 %) samples. Approximately 2.4 % of Thai isolates produced extended-spectrum β-lactamase (ESBL). All the ESBL producers possessed blaCTX-M-14, some of which were horizontally transferred. Class 1 integrons were common in Thai (31.9 %) and Laos (39.1 %) isolates, but none were associated with SGI1. The resistance cassette dfrA12-aadA2 was the most common, while the least common was aadA2-linG (n=1). The dfrA12-aadA2 gene cassette in five isolates and aadA2-linG were located on conjugative plasmid. Three pork isolates were fluoroquinolone resistant and carried an amino acid substitute, Ser-83-Tyr, in GyrA. The qnrS gene was found in 7.1 and 5.5 % of the Thai and Laos isolates, respectively, while qnrB was carried in another Laos isolate (1.9 %). All ESBL producers carried qnrS. In conclusion, multidrug-resistant Salmonella was common in pigs, pork and human samples in this region. The bacteria carried mobile genetic elements and resistance genes on conjugative plasmids that could be readily transferred to other bacterial species.

  2. Identification and Structural Analysis of Amino Acid Substitutions that Increase the Stability and Activity of Aspergillus niger Glucose Oxidase

    PubMed Central

    Marín-Navarro, Julia; Roupain, Nicole; Talens-Perales, David; Polaina, Julio

    2015-01-01

    Glucose oxidase is one of the most conspicuous commercial enzymes due to its many different applications in diverse industries such as food, chemical, energy and textile. Among these applications, the most remarkable is the manufacture of glucose biosensors and in particular sensor strips used to measure glucose levels in serum. The generation of ameliorated versions of glucose oxidase is therefore a significant biotechnological objective. We have used a strategy that combined random and rational approaches to isolate uncharacterized mutations of Aspergillus niger glucose oxidase with improved properties. As a result, we have identified two changes that increase significantly the enzyme's thermal stability. One (T554M) generates a sulfur-pi interaction and the other (Q90R/Y509E) introduces a new salt bridge near the interphase of the dimeric protein structure. An additional double substitution (Q124R/L569E) has no significant effect on stability but causes a twofold increase of the enzyme's specific activity. Our results disclose structural motifs of the protein which are critical for its stability. The combination of mutations in the Q90R/Y509E/T554M triple mutant yielded a version of A. niger glucose oxidase with higher stability than those previously described. PMID:26642312

  3. Study of the effects of salicylic acid on soybean mitochondrial lipids and respiratory properties using the alternative oxidase as a stress-reporter protein.

    PubMed

    Matos, Ana Rita; Mendes, Ana Teresa; Scotti-Campos, Paula; Arrabaça, João Daniel

    2009-12-01

    Biotic and abiotic stresses can lead to modifications in the lipid composition of cell membranes. Although mitochondria appear to be implicated in stress responses, little is known about the membrane lipid changes that occur in these organelles in plants. Besides cytochrome c oxidase, plant mitochondria have an alternative oxidase (AOX) that accepts electrons directly from ubiquinol, dissipating energy as heat. AOX upregulation occurs under a variety of stresses and its induction by salicylic acid (SA) has been observed in different plant species. AOX was also suggested to be used as a functional marker for cell reprogramming under stress. In the present study, we have used etiolated soybean (Glycine max (L.) Merr. cv Cresir) seedlings to study the effects of SA treatment on the lipid composition and the respiratory properties of hypocotyl mitochondria. AOX expression was studied in detail, as a reporter protein, to evaluate whether modifications in mitochondrial energy metabolism were occurring. In mitochondria extracted from SA-treated seedlings, AOX capacity and protein contents increased. Both AOX1 and AOX2b transcripts accumulated in response to SA, but with different kinetics. A reduction in external NADH oxidation capacity was observed, whereas succinate respiration remained unchanged. The phospholipid composition of mitochondria remained similar in control and SA-treated plants, but a reduction in the relative amount of linolenic acid was observed in phosphatidylcholine, phosphatidylethanolamine and cardiolipin. The possible causes of the fatty acid modifications observed, and the implications for mitochondrial metabolism are discussed.

  4. Family Day Care Training Curriculum (Lao).

    ERIC Educational Resources Information Center

    Nakatsu, Gail

    California's Family Day Care Training Program was designed to recruit and train, in 7 weeks, Lao, Vietnamese, and Chinese refugees to establish their own state-licensed, family day care homes. Topics in the program's curriculum include an introduction to family day care, state licenses for family day care, state licensing requirements for family…

  5. Lao National Literacy Survey 2001: Final Report

    ERIC Educational Resources Information Center

    Online Submission, 2004

    2004-01-01

    Background: Adult literacy rates are an important indicator for describing the status of education and development within a country. The Lao national literacy survey was undertaken in 2001 to provide a reliable source of literacy data which in turn will determine if the country will reach Education For All (EFA) goals agreed upon at the World…

  6. Girls' and Women's Education in Laos.

    ERIC Educational Resources Information Center

    United Nations Educational, Scientific and Cultural Organization, Bangkok (Thailand). Principal Regional Office for Asia and the Pacific.

    While girls and women in Laos are not the target of strong discriminatory practices, they are at a higher risk of dropping out of school and never attending school. Specific components have been developed within educational policies and strategies to address needs of and concerns for girls and women. Reasons that girls and women lack access to…

  7. Spatio-Temporal Detection of the Thiomonas Population and the Thiomonas Arsenite Oxidase Involved in Natural Arsenite Attenuation Processes in the Carnoulès Acid Mine Drainage

    PubMed Central

    Hovasse, Agnès; Bruneel, Odile; Casiot, Corinne; Desoeuvre, Angélique; Farasin, Julien; Hery, Marina; Van Dorsselaer, Alain; Carapito, Christine; Arsène-Ploetze, Florence

    2016-01-01

    The acid mine drainage (AMD) impacted creek of the Carnoulès mine (Southern France) is characterized by acid waters with a high heavy metal content. The microbial community inhabiting this AMD was extensively studied using isolation, metagenomic and metaproteomic methods, and the results showed that a natural arsenic (and iron) attenuation process involving the arsenite oxidase activity of several Thiomonas strains occurs at this site. A sensitive quantitative Selected Reaction Monitoring (SRM)-based proteomic approach was developed for detecting and quantifying the two subunits of the arsenite oxidase and RpoA of two different Thiomonas groups. Using this approach combined with FISH and pyrosequencing-based 16S rRNA gene sequence analysis, it was established here for the first time that these Thiomonas strains are ubiquitously present in minor proportions in this AMD and that they express the key enzymes involved in natural remediation processes at various locations and time points. In addition to these findings, this study also confirms that targeted proteomics applied at the community level can be used to detect weakly abundant proteins in situ. PMID:26870729

  8. CR-LAAO, an L-amino acid oxidase from Calloselasma rhodostoma venom, as a potential tool for developing novel immunotherapeutic strategies against cancer

    PubMed Central

    Costa, Tássia R.; Menaldo, Danilo L.; Zoccal, Karina F.; Burin, Sandra M.; Aissa, Alexandre F.; Castro, Fabíola A. de; Faccioli, Lúcia H.; Greggi Antunes, Lusânia M.; Sampaio, Suely V.

    2017-01-01

    L-amino acid oxidases from snake venoms have been described to possess various biological functions. In this study, we investigated the inflammatory responses induced in vivo and in vitro by CR-LAAO, an L-amino acid oxidase isolated from Calloselasma rhodostoma venom, and its antitumor potential. CR-LAAO induced acute inflammatory responses in vivo, with recruitment of neutrophils and release of IL-6, IL-1β, LTB4 and PGE2. In vitro, IL-6 and IL-1β production by peritoneal macrophages stimulated with CR-LAAO was dependent of the activation of the Toll-like receptors TLR2 and TLR4. In addition, CR-LAAO promoted apoptosis of HL-60 and HepG2 tumor cells mediated by the release of hydrogen peroxide and activation of immune cells, resulting in oxidative stress and production of IL-6 and IL-1β that triggered a series of events, such as activation of caspase 8, 9 and 3, and the expression of the pro-apoptotic gene BAX. We also observed that CR-LAAO modulated the cell cycle of these tumor cells, promoting delay in the G0/G1 and S phases. Taken together, our results suggest that CR-LAAO could serve as a potential tool for the development of novel immunotherapeutic strategies against cancer, since this toxin promoted apoptosis of tumor cells and also activated immune cells against them. PMID:28205610

  9. RNA interference of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO1 and ACO2) genes expression prolongs the shelf life of Eksotika (Carica papaya L.) papaya fruit.

    PubMed

    Sekeli, Rogayah; Abdullah, Janna Ong; Namasivayam, Parameswari; Muda, Pauziah; Abu Bakar, Umi Kalsom; Yeong, Wee Chien; Pillai, Vilasini

    2014-06-19

    The purpose of this study was to evaluate the effectiveness of using RNA interference in down regulating the expression of 1-aminocyclopropane-1-carboxylic acid oxidase gene in Eksotika papaya. One-month old embryogenic calli were separately transformed with Agrobacterium strain LBA 4404 harbouring the three different RNAi pOpOff2 constructs bearing the 1-aminocyclopropane-1-carboxylic acid oxidase gene. A total of 176 putative transformed lines were produced from 15,000 calli transformed, selected, then regenerated on medium supplemented with kanamycin. Integration and expression of the targeted gene in putatively transformed lines were verified by PCR and real-time RT-PCR. Confined field evaluation of a total of 31 putative transgenic lines planted showed a knockdown expression of the targeted ACO1 and ACO2 genes in 13 lines, which required more than 8 days to achieve the full yellow colour (Index 6). Fruits harvested from lines pRNAiACO2 L2-9 and pRNAiACO1 L2 exhibited about 20 and 14 days extended post-harvest shelf life to reach Index 6, respectively. The total soluble solids contents of the fruits ranged from 11 to 14° Brix, a range similar to fruits from non-transformed, wild type seed-derived plants.

  10. Cr(VI) reduction by gluconolactone and hydrogen peroxide, the reaction products of fungal glucose oxidase: Cooperative interaction with organic acids in the biotransformation of Cr(VI).

    PubMed

    Romo-Rodríguez, Pamela; Acevedo-Aguilar, Francisco Javier; Lopez-Torres, Adolfo; Wrobel, Kazimierz; Wrobel, Katarzyna; Gutiérrez-Corona, J Félix

    2015-09-01

    The Cr(VI) reducing capability of growing cells of the environmental A. tubingensis Ed8 strain is remarkably efficient compared to reference strains A. niger FGSC322 and A. tubingensis NRRL593. Extracellular glucose oxidase (GOX) activity levels were clearly higher in colonies developed in solid medium and in concentrated extracts of the spent medium of liquid cultures of the Ed8 strain in comparison with the reference strains. In addition, concentrated extracts of the spent medium of A. tubingensis Ed8, but not those of the reference strains, exhibited the ability to reduce Cr(VI). In line with this observation, it was found that A. niger purified GOX is capable of mediating the conversion of Cr(VI) to Cr(III) in a reaction dependent on the presence of glucose that is stimulated by organic acids. Furthermore, it was found that a decrease in Cr(VI) may occur in the absence of the GOX enzyme, as long as the reaction products gluconolactone and hydrogen peroxide are present; this conversion of Cr(VI) is stimulated by organic acids in a reaction that generates hydroxyl radicals, which may involve the formation of an intermediate peroxichromate(V) complex. These findings indicated that fungal glucose oxidase acts an indirect chromate reductase through the formation of Cr(VI) reducing molecules, which interact cooperatively with other fungal metabolites in the biotransformation of Cr(VI).

  11. Reactive oxygen species derived from xanthine oxidase interrupt dimerization of breast cancer resistance protein, resulting in suppression of uric acid excretion to the intestinal lumen.

    PubMed

    Ogura, Jiro; Kuwayama, Kaori; Sasaki, Shunichi; Kaneko, Chihiro; Koizumi, Takahiro; Yabe, Keisuke; Tsujimoto, Takashi; Takeno, Reiko; Takaya, Atsushi; Kobayashi, Masaki; Yamaguchi, Hiroaki; Iseki, Ken

    2015-09-01

    The prevalence of hyperuricemia/gout increases with aging. However, the effect of aging on function for excretion of uric acid to out of the body has not been clarified. We found that ileal uric acid clearance in middle-aged rats (11-12 months) was decreased compared with that in young rats (2 months). In middle-aged rats, xanthine oxidase (XO) activity in the ileum was significantly higher than that in young rats. Inosine-induced reactive oxygen species (ROS), which are derived from XO, also decreased ileal uric acid clearance. ROS derived from XO decreased the active homodimer level of breast cancer resistance protein (BCRP), which is a uric acid efflux transporter, in the ileum. Pre-administration of allopurinol recovered the BCRP homodimer level, resulting in the recovering ileal uric acid clearance. Moreover, we investigated the effects of ROS derived from XO on BCRP homodimer level directly in Caco-2 cells using hypoxanthine. Treatment with hypoxanthine decreased BCRP homodimer level. Treatment with hypoxanthine induced mitochondrial dysfunction, suggesting that the decreasing BCRP homodimer level might be caused by mitochondrial dysfunction. In conclusion, ROS derived from XO decrease BCRP homodimer level, resulting in suppression of function for uric acid excretion to the ileal lumen. ROS derived from XO may cause the suppression of function of the ileum for the excretion of uric acid with aging. The results of our study provide a new insight into the causes of increasing hyperuricemia/gout prevalence with aging.

  12. Cloning, characterization and expression of escapin, a broadly antimicrobial FAD-containing L-amino acid oxidase from ink of the sea hare Aplysia californica.

    PubMed

    Yang, Hsiuchin; Johnson, Paul Micah; Ko, Ko-Chun; Kamio, Michiya; Germann, Markus W; Derby, Charles D; Tai, Phang C

    2005-09-01

    A 60 kDa monomeric protein isolated from the defensive purple ink secretion of the sea hare Aplysia californica was cloned and sequenced, and is the first sea hare antimicrobial protein to be functionally expressed in E. coli. Sequence analysis suggested that this protein is a flavin-containing l-amino acid oxidase (LAAO), with one predicted potential glycosylation site, although the glycosylation could not be experimentally confirmed. This protein, which we call ;escapin', has high sequence similarity to several other gastropod proteins. Escapin was verified by NMR, mass spectroscopy and HPLC to have FAD as its flavin cofactor. Escapin's antimicrobial effects, bacteriostasis and bactericidal, were determined using a combination of two assays: (1) incubation of bacteria on solid media followed by assessment of inhibition by direct observation of zones of inhibition or by turbidity measurements; and (2) incubation of bacteria in liquid media followed by counting viable colonies after growing on agar plates. Native escapin inhibited the growth of Gram-positive and Gram-negative bacteria, including marine bacteria (Vibrio harveyii and Staphylococcus aureus) and pathogenic bacteria (Staphylococcus aureus, Streptococcus pyogenes and Pseudomonas aeruginosa). Escapin also inhibited the growth of yeast and fungi, with different efficacies. Escapin's antimicrobial activity was concentration dependent and did not decrease when stored for more than 5 months at room temperature. Escapin was bacteriostatic and not bactericidal in minimal media (e.g. salt media) with glucose, yeast extract, and a mixture of 20 amino acids each at 50 micromol l(-1), but was bactericidal in media enriched with Tryptone Peptone. Escapin was also strongly bactericidal in media with l-lysine at concentrations as low as 3 mmol l(-1) and slightly bactericidal in 50 mmol l(-1) l-arginine, but not in most other amino acids even at 50 mmol l(-1). Escapin had high oxidase activity (producing hydrogen

  13. POSIVA funds further projects in Laos.

    PubMed

    1998-10-01

    Laos has for the first time received funding through the Postal Savings International Voluntary Aid (POSIVA) scheme. The funds will be used by JOICFP for projects in Bolikhamsay Province under the supervision of the Lao Institute for Mother and Child Health (IMCH). JOICFP has been working since 1992 in Taphabat and Paksane districts of the province, under UNFPA's Asia Regional Project, focusing upon providing quality, core reproductive health services to communities from the provincial and district levels. A need now exists to focus more upon providing such services at the commune level since the Community Health Centers (CHCs) are underutilized, staff are becoming more capable, and demand for services has grown. Bolikhan district will also be included in the POSIVA project. A total of 11 CHCs will be upgraded in the districts through the training of health staff and village volunteers, the acquisition of basic medical equipment and essential drugs, and the provision of information, education, and communication materials.

  14. The Apoplastic Copper AMINE OXIDASE1 Mediates Jasmonic Acid-Induced Protoxylem Differentiation in Arabidopsis Roots1

    PubMed Central

    Ghuge, Sandip A.; Carucci, Andrea; Rodrigues-Pousada, Renato A.; Tisi, Alessandra; Franchi, Stefano; Tavladoraki, Paraskevi; Cona, Alessandra

    2015-01-01

    Polyamines are involved in key developmental processes and stress responses. Copper amine oxidases oxidize the polyamine putrescine (Put), producing an aldehyde, ammonia, and hydrogen peroxide (H2O2). The Arabidopsis (Arabidopsis thaliana) amine oxidase gene At4g14940 (AtAO1) encodes an apoplastic copper amine oxidase expressed at the early stages of vascular tissue differentiation in roots. Here, its role in root development and xylem differentiation was explored by pharmacological and forward/reverse genetic approaches. Analysis of the AtAO1 expression pattern in roots by a promoter::green fluorescent protein-β-glucuronidase fusion revealed strong gene expression in the protoxylem at the transition, elongation, and maturation zones. Methyl jasmonate (MeJA) induced AtAO1 gene expression in vascular tissues, especially at the transition and elongation zones. Early protoxylem differentiation was observed upon MeJA treatment along with Put level decrease and H2O2 accumulation in wild-type roots, whereas Atao1 loss-of-function mutants were unresponsive to the hormone. The H2O2 scavenger N,N1-dimethylthiourea reversed the MeJA-induced early protoxylem differentiation in wild-type seedlings. Likewise, Put, which had no effect on Atao1 mutants, induced early protoxylem differentiation in the wild type, this event being counteracted by N,N1-dimethylthiourea treatment. Consistently, AtAO1-overexpressing plants showed lower Put levels and early protoxylem differentiation concurrent with H2O2 accumulation in the root zone where the first protoxylem cells with fully developed secondary wall thickenings are found. These results show that the H2O2 produced via AtAO1-driven Put oxidation plays a role in MeJA signaling leading to early protoxylem differentiation in root. PMID:25883242

  15. Expression of Mitochondrial Cytochrome C Oxidase Chaperone Gene (COX20) Improves Tolerance to Weak Acid and Oxidative Stress during Yeast Fermentation

    PubMed Central

    Kumar, Vinod; Hart, Andrew J.; Keerthiraju, Ethiraju R.; Waldron, Paul R.; Tucker, Gregory A.; Greetham, Darren

    2015-01-01

    Introduction Saccharomyces cerevisiae is the micro-organism of choice for the conversion of fermentable sugars released by the pre-treatment of lignocellulosic material into bioethanol. Pre-treatment of lignocellulosic material releases acetic acid and previous work identified a cytochrome oxidase chaperone gene (COX20) which was significantly up-regulated in yeast cells in the presence of acetic acid. Results A Δcox20 strain was sensitive to the presence of acetic acid compared with the background strain. Overexpressing COX20 using a tetracycline-regulatable expression vector system in a Δcox20 strain, resulted in tolerance to the presence of acetic acid and tolerance could be ablated with addition of tetracycline. Assays also revealed that overexpression improved tolerance to the presence of hydrogen peroxide-induced oxidative stress. Conclusion This is a study which has utilised tetracycline-regulated protein expression in a fermentation system, which was characterised by improved (or enhanced) tolerance to acetic acid and oxidative stress. PMID:26427054

  16. Identification of L-amino acid oxidase (Mb-LAAO) with antibacterial activity in the venom of Montivipera bornmuelleri, a viper from Lebanon.

    PubMed

    Rima, Mohamad; Accary, Claudine; Haddad, Katia; Sadek, Riyad; Hraoui-Bloquet, Souad; Desfontis, Jean C; Fajloun, Ziad

    2013-10-01

    The L-amino acid oxidase (LAAO) is a multifunctional enzyme, able to partake in different activities including antibacterial activity. In this study, a novel LAAO (Mb-LAAO) was isolated from the venom of M. bornmuelleri snake using size exclusion chromatography followed by RP-HPLC and partially characterized. However, the molecular weight of the Mb-LAAO determined by ESI-MS and SDS-PAGE was 59 960.4 Da. Once the enzymatic activity test confirming the enzyme's identity (transformation of L-leucine) was done, the Mb-LAAO was evaluated for its antibacterial activity against Gram-negative bacteria. It showed a remarkable effect against M. morganii and K. pneumoniae. Moreover, no cytotoxic activity was observed for Mb-LAAO against human erythrocytes arguing for an exploration of its pharmaceutical interest.

  17. Chlorpromazine oligomer is a potentially active substance that inhibits human D-amino acid oxidase, product of a susceptibility gene for schizophrenia.

    PubMed

    Iwana, Sanae; Kawazoe, Tomoya; Park, Hwan Ki; Tsuchiya, Koichiro; Ono, Koji; Yorita, Kazuko; Sakai, Takashi; Kusumi, Takenori; Fukui, Kiyoshi

    2008-12-01

    D-amino acid oxidase (DAO), a potential risk factor for schizophrenia, has been proposed to be involved in the decreased glutamatergic neurotransmission in schizophrenia. Here we show the inhibitory effect of an antipsychotic drug, chlorpromazine, on human DAO, which is consistent with previous reports using porcine DAO, although human DAO was inhibited to a lesser degree (K(i) = 0.7 mM) than porcine DAO. Since chlorpromazine is known to induce phototoxic or photoallergic reactions and also to be transformed into various metabolites, we examined the effects of white light-irradiated chlorpromazine on the enzymatic activity. Analytical methods including high-resolution mass spectrometry revealed that irradiation triggered the oligomerization of chlorpromazine molecules. The oligomerized chlorpromazine showed a mixed type inhibition with inhibition constants of low micromolar range, indicative of enhanced inhibition. Taken together, these results suggest that oligomerized chlorpromazine could act as an active substance that might contribute to the therapeutic effects of this drug.

  18. Selected biochemical properties of polyphenol oxidase in butter lettuce leaves (Lactuca sativa L. var. capitata) elicited with dl-β-amino-n-butyric acid.

    PubMed

    Złotek, Urszula; Gawlik-Dziki, Urszula

    2015-02-01

    The study concentrated on changes in certain biochemical parameters of polyphenol oxidase (PPO) from lettuce leaves caused by dl-β-amino-n-butyric acid (BABA) elicitation. PPO from control plants demonstrated the highest affinity toward catechol, whereas PPO from BABA-elicited lettuce showed the highest affinity to 4-methylcatechol. The optimum temperature for enzymes from control plants was 35°C, whereas from plants elicited with 1mM BABA this was 25°C. PPO from plants elicited with BABA was also more sensitive to the tested inhibitors than PPO from control plants. l-Cysteine was the most effective inhibitor. Native gel stained for PPO activity in control samples showed two isoforms. However, in BABA-treated lettuce three bands visualising PPO activity were observed. The information obtained in this study will be valuable for the development of treatment technology and storage conditions to control undesirable browning reactions in elicited lettuce.

  19. Synergistic effect of Aspergillus tubingensis CTM 507 glucose oxidase in presence of ascorbic acid and alpha amylase on dough properties, baking quality and shelf life of bread.

    PubMed

    Kriaa, Mouna; Ouhibi, Rabeb; Graba, Héla; Besbes, Souhail; Jardak, Mohamed; Kammoun, Radhouane

    2016-02-01

    The impact of Aspergillus tubingensis glucose oxidase (GOD) in combination with α-amylase and ascorbic acid on dough properties, qualities and shelf life of bread was investigated. Regression models of alveograph and texture parameters of dough and bread were adjusted. Indeed, the mixture of GOD (44 %) and ascorbic acid (56 %) on flour containing basal improver showed its potential as a corrective action to get better functional and rheological properties of dough and bread texture. Furthermore, wheat flour containing basal additives and enriched with GOD (63.8 %), ascorbic acid (32 %) and α- amylase (4.2 %) led to high technological bread making parameters, to decrease the crumb firmness and chewiness and to improve elasticity, adhesion, cohesion and specific volume of bread. In addition to that, the optimized formulation addition significantly reduced water activity and therefore decreased bread susceptibility to microbial spoilage. These findings demonstrated that GOD could partially substitute not only ascorbic acid but also α-amylase. The generated models allowed to predict the behavior of wheat flour containing additives in the range of values tested and to define the additives formula that led to desired rheological and baking qualities of dough. This fact provides new perspectives to compensate flour quality deficiencies at the moment of selecting raw materials and technological parameters reducing the production costs and facilitating gluten free products development. Graphical abstractᅟ.

  20. Multivalent Interactions of Human Primary Amine Oxidase with the V and C22 Domains of Sialic Acid-Binding Immunoglobulin-Like Lectin-9 Regulate Its Binding and Amine Oxidase Activity

    PubMed Central

    Fair-Mäkelä, Ruth; Salo-Ahen, Outi M. H.; Guédez, Gabriela; Bligt-Lindén, Eva; Grönholm, Janne; Jalkanen, Sirpa; Salminen, Tiina A.

    2016-01-01

    Sialic acid-binding immunoglobulin-like lectin-9 (Siglec-9) on leukocyte surface is a counter-receptor for endothelial cell surface adhesin, human primary amine oxidase (hAOC3), a target protein for anti-inflammatory agents. This interaction can be used to detect inflammation and cancer in vivo, since the labeled peptides derived from the second C2 domain (C22) of Siglec-9 specifically bind to the inflammation-inducible hAOC3. As limited knowledge on the interaction between Siglec-9 and hAOC3 has hampered both hAOC3-targeted drug design and in vivo imaging applications, we have now produced and purified the extracellular region of Siglec-9 (Siglec-9-EC) consisting of the V, C21 and C22 domains, modeled its 3D structure and characterized the hAOC3–Siglec-9 interactions using biophysical methods and activity/inhibition assays. Our results assign individual, previously unknown roles for the V and C22 domains. The V domain is responsible for the unusually tight Siglec-9–hAOC3 interactions whereas the intact C22 domain of Siglec-9 is required for modulating the enzymatic activity of hAOC3, crucial for the hAOC3-mediated leukocyte trafficking. By characterizing the Siglec-9-EC mutants, we could conclude that R120 in the V domain likely interacts with the terminal sialic acids of hAOC3 attached glycans whereas residues R284 and R290 in C22 are involved in the interactions with the active site channel of hAOC3. Furthermore, the C22 domain binding enhances the enzymatic activity of hAOC3 although the sialic acid-binding capacity of the V domain of Siglec-9 is abolished by the R120S mutation. To conclude, our results prove that the V and C22 domains of Siglec-9-EC interact with hAOC3 in a multifaceted and unique way, forming both glycan-mediated and direct protein-protein interactions, respectively. The reported results on the mechanism of the Siglec-9–hAOC3 interaction are valuable for the development of hAOC3-targeted therapeutics and diagnostic tools. PMID:27893774

  1. [Alternative oxidase in industrial fungi].

    PubMed

    Gu, Shuai; Liu, Qiang; He, Hao; Li, Shuang

    2015-01-01

    Filamentous fungi have been used in industrial fermentation extensively. Based on non-phosphorylating electron transport process, alternative respiration pathway (ARP) acts as an energy overflow, which can balance carbon metabolism and electron transport, allow the continuance of tricarboxylic acid cycle without the formation of ATP, and permit the turnover of carbon skeletons. Alternative respiration pathway also plays an important role in the stress response of fungi and the physiological function of conditioned pathogen. Alternative oxidase (AOX) is the terminal oxidase responsible for the activity of alternative respiration pathway, which exists widely in higher plants, parts of fungi and algae. Owing to the property that alternative oxidase (AOX) is sensitive to salicylhydroxamic acid (SHAM) and insensitive to conventional inhibitors of cytochrome respiration, alternative respiration pathway by AOX is also named as cyanide-resistant respiration (CRR). In recent years, the study of the alternative respiration pathway and alternative oxidase has been a hot topic in the area involving cellular respiration metabolism. In this review we summarized the latest research advances about the functions of alternative respiration pathway and alternative oxidase in industrial fungi.

  2. Acanthamoeba polyphaga mimivirus virophage seroconversion in travelers returning from Laos.

    PubMed

    Parola, Philippe; Renvoisé, Aurélie; Botelho-Nevers, Elisabeth; La Scola, Bernard; Desnues, Christelle; Raoult, Didier

    2012-09-01

    During January 2010, a husband and wife returned from Laos to France with probable parasitic disease. Increased antibodies against an Acanthamoeba polyphaga mimivirus virophage indicated seroconversion. While in Laos, they had eaten raw fish, a potential source of the virophage. This virophage, associated with giant viruses suspected to cause pneumonia, could be an emerging pathogen.

  3. Large-Scale Survey for Tickborne Bacteria, Khammouan Province, Laos

    PubMed Central

    Vongphayloth, Khamsing; Vongsouvath, Malavanh; Grandadam, Marc; Brey, Paul T.; Newton, Paul N.; Sutherland, Ian W.; Dittrich, Sabine

    2016-01-01

    We screened 768 tick pools containing 6,962 ticks from Khammouan Province, Laos, by using quantitative real-time PCR and identified Rickettsia spp., Ehrlichia spp., and Borrelia spp. Sequencing of Rickettsia spp.–positive and Borrelia spp.–positive pools provided evidence for distinct genotypes. Our results identified bacteria with human disease potential in ticks in Laos. PMID:27532491

  4. Dynamic aspects of ascorbic acid metabolism in the circulation: analysis by ascorbate oxidase with a prolonged in vivo half-life.

    PubMed

    Kasahara, Emiko; Kashiba, Misato; Jikumaru, Mika; Kuratsune, Daisuke; Orita, Kumi; Yamate, Yurika; Hara, Kenjiro; Sekiyama, Atsuo; Sato, Eisuke F; Inoue, Masayasu

    2009-06-26

    Because AA (L-ascorbic acid) scavenges various types of free radicals to form MDAA (monodehydroascorbic acid) and DAA (dehydroascorbic acid), its regeneration from the oxidized metabolites is critically important for humans and other animals that lack the ability to synthesize this antioxidant. To study the dynamic aspects of AA metabolism in the circulation, a long acting AOase (ascorbate oxidase) derivative was synthesized by covalently linking PEG [poly(ethylene glycol)] to the enzyme. Fairly low concentrations of the modified enzyme (PEG-AOase) rapidly decreased AA levels in isolated fresh plasma and blood samples with a concomitant increase in their levels of MDAA and DAA. In contrast, relatively high doses of PEG-AOase were required to decrease the circulating plasma AA levels of both normal rats and ODS (osteogenic disorder Shionogi) rats that lack the ability to synthesize AA. Administration of 50 units of PEG-AOase/kg of body weight rapidly decreased AA levels in plasma and the kidney without affecting the levels in other tissues, such as the liver, brain, lung, adrenal grand and skeletal muscles. PEG-AOase slightly, but significantly, decreased glutathione (GSH) levels in the liver without affecting those in other tissues. Suppression of hepatic synthesis of GSH by administration of BSO [L-buthionin-(S,R)-sulfoximine] enhanced the PEG-AOase-induced decrease in plasma AA levels. These and other results suggest that the circulating AA is reductively regenerated from MDAA extremely rapidly and that hepatic GSH plays important roles in the regeneration of this antioxidant.

  5. Construction of a D-amino acid oxidase reactor based on magnetic nanoparticles modified by a reactive polymer and its application in screening enzyme inhibitors.

    PubMed

    Mu, Xiaoyu; Qiao, Juan; Qi, Li; Liu, Ying; Ma, Huimin

    2014-08-13

    Developing facile and high-throughput methods for exploring pharmacological inhibitors of D-amino acid oxidase (DAAO) has triggered increasing interest. In this work, DAAO was immobilized on the magnetic nanoparticles, which were modified by a biocompatible reactive polymer, poly(glycidyl methacrylate) (PGMA) via an atom transfer radical polymerization technique. Interestingly, the enzyme immobilization process was greatly promoted with the assistance of a lithium perchlorate catalyst. Meanwhile, a new amino acid ionic liquid (AAIL) was successfully synthesized and employed as the efficient chiral ligand in a chiral ligand exchange capillary electrophoresis (CLE-CE) system for chiral separation of amino acids (AAs) and quantitation of methionine, which was selected as the substrate of DAAO. Then, the apparent Michaelis-Menten constants in the enzyme system were determined with the proposed CLE-CE method. The prepared DAAO-PGMA-Fe3O4 nanoparticles exhibited excellent reusability and good stability. Moreover, the enzyme reactor was successfully applied in screening DAAO inhibitors. These results demonstrated that the enzyme could be efficiently immobilized on the polymer-grafted magnetic nanoparticles and that the obtained enzyme reactor has great potential in screening enzyme inhibitors, further offering new insight into monitoring the relevant diseases.

  6. Devonian radiolarians and tentaculitids from central Laos

    NASA Astrophysics Data System (ADS)

    Thassanapak, Hathaithip; Udchachon, Mongkol; Burrett, Clive

    2012-10-01

    A 4 m thick section of silicified shales from Ban Phonxai in central Laos contains the radiolarians Trilonche davidi, T. hindea, T. minax, T. palimbola, Stigmosphaerostylus spp. and Ceratoikiscum ? sp. and the tentaculitids Homoctenus ultimus and Costulatostylionina vesca which together indicate a Frasnian age. This pelagic, deep shelf fauna from the Indochina Terrane is similar to that from South China and shows that tentaculitids may be common and biostratigraphically useful in radiolarian cherts and shales in South East Asia. This discovery probably necessitates mapping of the Late Devonian Phon Tiou Fm in this area which is currently mapped as the Early Carboniferous Boulapha Formation.

  7. Aldehyde oxidase 1 is highly abundant in hepatic steatosis and is downregulated by adiponectin and fenofibric acid in hepatocytes in vitro

    SciTech Connect

    Neumeier, Markus; Weigert, Johanna; Schaeffler, Andreas; Weiss, Thomas S.; Schmidl, Christian; Buettner, Roland; Bollheimer, Cornelius; Aslanidis, Charalampos; Schoelmerich, Juergen; Buechler, Christa . E-mail: christa.buechler@klinik.uni-regensburg.de

    2006-11-24

    Adiponectin protects the liver from steatosis caused by obesity or alcohol and therefore the influence of adiponectin on human hepatocytes was analyzed. GeneChip experiments indicated that recombinant adiponectin downregulates aldehyde oxidase 1 (AOX1) expression and this was confirmed by real-time RT-PCR and immunoblot. AOX1 is a xenobiotic metabolizing protein and produces reactive oxygen species (ROS), that promote cell damage and fibrogenesis. Adiponectin and fenofibric acid activate peroxisome proliferator-activated receptor-{alpha} (PPAR-{alpha}) and both suppress AOX1 protein and this is blocked by the PPAR-{alpha} antagonist RU486. Obesity is associated with low adiponectin, reduced hepatic PPAR-{alpha} activity and fatty liver, and AOX1 was found induced in the liver of rats on a high-fat diet when compared to controls. Free fatty acids and leptin, that are elevated in obesity, failed to upregulate AOX1 in vitro. The current data indicate that adiponectin reduces AOX1 by activating PPAR-{alpha} whereas fatty liver disease is associated with elevated hepatic AOX1. High AOX1 may be associated with higher ROS well described to induce fibrogenesis in liver tissue but may also influence drug metabolism and activity.

  8. Identification of potent bactericidal compounds produced by escapin, an L-amino acid oxidase in the ink of the sea hare Aplysia californica.

    PubMed

    Ko, Ko-Chun; Wang, Binghe; Tai, Phang C; Derby, Charles D

    2008-12-01

    The ink of sea hares (Aplysia californica) contains escapin, an L-amino acid oxidase that metabolizes L-lysine, thereby producing a mixture that kills microbes and deters attacking predators. This secretion contains H2O2,ammonia, and an equilibrium mixture of "escapin intermediate product" (EIP-K) that includes alpha-keto-epsilon-aminocaproic acid and several other molecules. Components of the equilibrium mixture react nonenzymatically with H2O2 to form "escapin end product" (EEP-K), which contains delta-aminovaleric acid and delta-valerolactam. The proportions of the molecules in this equilibrium mixture change with pH, and this is biologically important because the secretion is pH 5 when released but becomes pH 8 when fully diluted in seawater. The goal of the current study was to identify which molecules in this equilibrium mixture are bactericidal. We show that a mixture of H2O2 and EIP-K, but not EEP-K, at low mM concentrations is synergistically responsible for most of the bactericidal activity of the secretion against Escherichia coli, Vibrio harveyi, Staphylococcus aureus,and Pseudomonas aeruginosa. Low pH enhances the bactericidal effect, and this does not result from stress associated with low pH itself. Sequential exposure to low mM concentrations of EIP-K and H2O2, in either order, does not kill E. coli. Reaction products formed when L-arginine is substituted for L-lysine have almost no bactericidal activity. Our results favor the idea that the bactericidal activity is due to unstable intermediates of the reaction of alpha-keto-epsilon-aminocaproic acid with H2O2.

  9. Inhibition of NADPH oxidase activation by synthetic peptides mapping within the carboxyl-terminal domain of small GTP-binding proteins. Lack of amino acid sequence specificity and importance of polybasic motif.

    PubMed

    Joseph, G; Gorzalczany, Y; Koshkin, V; Pick, E

    1994-11-18

    The small GTP-binding protein (G protein) Rac1 is an obligatory participant in the assembly of the superoxide (O2-.)-generating NADPH oxidase complex of macrophages. We investigated the effect of synthetic peptides, mapping within the near carboxyl-terminal domains of Rac1 and of related G proteins, on the activity of NADPH oxidase in a cell-free system consisting of solubilized guinea pig macrophage membrane, a cytosolic fraction enriched in p47phox and p67phox (or total cytosol), highly purified Rac1-GDP dissociation inhibitor for Rho (Rho GDI) complex, and the activating amphiphile, lithium dodecyl sulfate. Peptides Rac1-(178-188) and Rac1-(178-191), but not Rac2-(178-188), inhibited NADPH oxidase activity in a Rac1-dependent system when added prior to or simultaneously with the initiation of activation. However, undecapeptides corresponding to the near carboxyl-terminal domains of RhoA and RhoC and, most notably, a peptide containing the same amino acids as Rac1-(178-188), but in reversed orientation, were also inhibitory. Surprisingly, O2-. production in a Rac2-dependent cell-free system was inhibited by Rac1-(178-188) but not by Rac2-(178-188). Finally, basic polyamino acids containing lysine, histidine, or arginine, also inhibited NADPH oxidase activation. We conclude that inhibition of NADPH oxidase activation by synthetic peptides mapping within the carboxyl-terminal domain of certain small G proteins is not amino acid sequence-specific but related to the presence of a polybasic motif. It has been proposed that such a motif serves as a plasma membrane targeting signal for a number of small G proteins (Hancock, J.F., Paterson, H., and Marshall, C.J. (1990) Cell 63, 133-139).

  10. Prokaryotic orthologues of mitochondrial alternative oxidase and plastid terminal oxidase.

    PubMed

    McDonald, Allison E; Amirsadeghi, Sasan; Vanlerberghe, Greg C

    2003-12-01

    The mitochondrial alternative oxidase (AOX) and the plastid terminal oxidase (PTOX) are two similar members of the membrane-bound diiron carboxylate group of proteins. AOX is a ubiquinol oxidase present in all higher plants, as well as some algae, fungi, and protists. It may serve to dampen reactive oxygen species generation by the respiratory electron transport chain. PTOX is a plastoquinol oxidase in plants and some algae. It is required in carotenoid biosynthesis and may represent the elusive oxidase in chlororespiration. Recently, prokaryotic orthologues of both AOX and PTOX proteins have appeared in sequence databases. These include PTOX orthologues present in four different cyanobacteria as well as an AOX orthologue in an alpha-proteobacterium. We used PCR, RT-PCR and northern analyses to confirm the presence and expression of the PTOX gene in Anabaena variabilis PCC 7120. An extensive phylogeny of newly found prokaryotic and eukaryotic AOX and PTOX proteins supports the idea that AOX and PTOX represent two distinct groups of proteins that diverged prior to the endosymbiotic events that gave rise to the eukaryotic organelles. Using multiple sequence alignment, we identified residues conserved in all AOX and PTOX proteins. We also provide a scheme to readily distinguish PTOX from AOX proteins based upon differences in amino acid sequence in motifs around the conserved iron-binding residues. Given the presence of PTOX in cyanobacteria, we suggest that this acronym now stand for plastoquinol terminal oxidase. Our results have implications for the photosynthetic and respiratory metabolism of these prokaryotes, as well as for the origin and evolution of eukaryotic AOX and PTOX proteins.

  11. Novel L-amino acid oxidase with antibacterial activity against methicillin-resistant Staphylococcus aureus isolated from epidermal mucus of the flounder Platichthys stellatus.

    PubMed

    Kasai, Kosuke; Ishikawa, Takashi; Komata, Takafumi; Fukuchi, Kaori; Chiba, Mitsuru; Nozaka, Hiroyuki; Nakamura, Toshiya; Sato, Tatsusuke; Miura, Tomisato

    2010-01-01

    Fish produce mucus substances as a defensive outer barrier against environmental xenobiotics and predators. Recently, we found a bioactive protein in the mucus layer of the flounder Platichthys stellatus, which showed antibacterial activity against Staphylococcus epidermidis, Staphylococcus aureus and methicillin-resistant S. aureus. In this study, we isolated and identified the antibacterial protein from the mucus components of P. stellatus using a series of column chromatography steps. We then performed gel electrophoresis and cDNA cloning to characterize the protein. The antibacterial protein in the mucus had a molecular mass of approximately 52 kDa with an isoelectric point of 5.3, and cDNA sequencing showed that it corresponded completely with the peptide sequence of antibacterial protein from the gill. A BLAST search suggested that the cDNA encoded an antibacterial protein sharing identity with a number of L-amino acid oxidases (LAAOs) and possessing several conserved motifs found in flavoproteins. RT-PCR using a specific primer, and immunohistochemical analysis with anti-LAAO IgG, demonstrated tissue-specific expression and localization in the gill. Moreover, the anti-LAAO IgG was able to neutralize the antibacterial activity of the protein against methicillin-resistant S. aureus. Thus, we demonstrated that this antibacterial protein, identified from P. stellatus-derived epidermal mucus, is a novel LAAO-like protein with antibacterial activity, similar to snake LAAOs.

  12. Overexpression of Arabidopsis thaliana gibberellic acid 20 oxidase (AtGA20ox) gene enhance the vegetative growth and fiber quality in kenaf (Hibiscus cannabinus L.) plants.

    PubMed

    Withanage, Samanthi Priyanka; Hossain, Md Aktar; Kumar M, Sures; Roslan, Hairul Azman B; Abdullah, Mohammad Puad; Napis, Suhaimi B; Shukor, Nor Aini Ab

    2015-06-01

    Kenaf (Hibiscus cannabinus L.; Family: Malvaceae), is multipurpose crop, one of the potential alternatives of natural fiber for biocomposite materials. Longer fiber and higher cellulose contents are required for good quality biocomposite materials. However, average length of kenaf fiber (2.6 mm in bast and 1.28 mm in whole plant) is below the critical length (4 mm) for biocomposite production. Present study describes whether fiber length and cellulose content of kenaf plants could be enhanced by increasing GA biosynthesis in plants by overexpressing Arabidopsis thaliana Gibberellic Acid 20 oxidase (AtGA20ox) gene. AtGA20ox gene with intron was overexpressed in kenaf plants under the control of double CaMV 35S promoter, followed by in planta transformation into V36 and G4 varieties of kenaf. The lines with higher levels of bioactive GA (0.3-1.52 ng g(-1) fresh weight) were further characterized for their morphological and biochemical traits including vegetative and reproductive growth, fiber dimension and chemical composition. Positive impact of increased gibberellins on biochemical composition, fiber dimension and their derivative values were demonstrated in some lines of transgenic kenaf including increased cellulose content (91%), fiber length and quality but it still requires further study to confirm the critical level of this particular bioactive GA in transgenic plants.

  13. Monomeric L-amino acid oxidase-induced mitochondrial dysfunction in Rhizoctonia solani Reveals a novel antagonistic mechanism of Trichoderma harzianum ETS 323.

    PubMed

    Yang, Chia-Ann; Cheng, Chi-Hua; Lee, Jeng-Woei; Lo, Chaur-Tsuen; Liu, Shu-Ying; Peng, Kou-Cheng

    2012-03-14

    The monomeric L-amino acid oxidase (mTh-LAAO) of Trichoderma harzianum ETS 323 has been suggested to antagonize Rhizoctonia solani by an unknown mechanism. Here, the mTh-LAAO-treated R. solani exhibited hyphal lysis and apoptotic characteristics such as DNA fragmentation, reactive oxygen species (ROS) accumulation, lipid peroxidation, and mitochondrial membrane potential depolarization. This hyphal lysis was suppressed by the mitochondria-dependent apoptosis inhibitor oligomycin while accompanied by reduction of ROS accumulation. This result suggested that mitochondria-mediated apoptosis in R. solani was involved in mTh-LAAO-induced growth inhibition, which was supported by the evidence of cytocheome c release and activation of caspases 9 and 3. Furthermore, the data indicated that the mTh-LAAO-induced fungal cell death was also closely interrelated with the interaction of mTh-LAAO with R. solani hyphal cell wall proteins. These results illuminate the biological function and mechanism underlying the antagonistic action of T. harzianum mTh-LAAO against fungal pathogens.

  14. Spontaneously Occurring Formation of Intranuclear and Cytoplasmic Inclusions in Renal Proximal Epithelium Due to Accumulation of D-Amino Acid Oxidase in Wistar Hannover Rats.

    PubMed

    Shimoyama, Natsumi; Nakatsuji, Shunji; Andoh, Rie; Yamaguchi, Yuko; Tamura, Kazutoshi; Hoshiya, Toru

    2015-07-01

    Intranuclear and cytoplasmic inclusions in the renal proximal tubular epithelium were observed in nontreated male and female Wistar Hannover rats in a 26-week study (32 weeks of age) and a 104-week study (110 weeks of age). The incidence rates were less than 5% in these two studies. In affected animals, the inclusions were observed in more than 60% of proximal tubular epithelium as various sized (approximately 1-8 μm in diameter) round and eosinophilic materials, but not in distal tubules, Henle's loop, or collecting ducts. Ultrastructurally, inclusions appeared finely granular, homogenous with middle-electron density, and without a limiting membrane. These inclusions were determined to be protein histochemically stained by Azan-Mallory and immunoreactive with an antibody against D-amino acid oxidase (DAO). There was no abnormality in in-life observations or in clinical test values suggestive of renal dysfunction. There were no associated degenerative or inflammatory changes in the kidneys, and no similar inclusions were observed in the other organs. These inclusions are very similar to propiverine hydrochloride (propiverine) and norepinephreine/serotonin reuptake inhibitor-induced inclusions. This is the first report of accumulation of DAO and formation of inclusions occurring spontaneously in rat kidneys. The data are important for toxicological studies using Wistar Hannover rats.

  15. Overexpression of Arabidopsis thaliana gibberellic acid 20 oxidase (AtGA20ox) gene enhance the vegetative growth and fiber quality in kenaf (Hibiscus cannabinus L.) plants

    PubMed Central

    Withanage, Samanthi Priyanka; Hossain, Md Aktar; Kumar M., Sures; Roslan, Hairul Azman B; Abdullah, Mohammad Puad; Napis, Suhaimi B.; Shukor, Nor Aini Ab.

    2015-01-01

    Kenaf (Hibiscus cannabinus L.; Family: Malvaceae), is multipurpose crop, one of the potential alternatives of natural fiber for biocomposite materials. Longer fiber and higher cellulose contents are required for good quality biocomposite materials. However, average length of kenaf fiber (2.6 mm in bast and 1.28 mm in whole plant) is below the critical length (4 mm) for biocomposite production. Present study describes whether fiber length and cellulose content of kenaf plants could be enhanced by increasing GA biosynthesis in plants by overexpressing Arabidopsis thaliana Gibberellic Acid 20 oxidase (AtGA20ox) gene. AtGA20ox gene with intron was overexpressed in kenaf plants under the control of double CaMV 35S promoter, followed by in planta transformation into V36 and G4 varieties of kenaf. The lines with higher levels of bioactive GA (0.3–1.52 ng g−1 fresh weight) were further characterized for their morphological and biochemical traits including vegetative and reproductive growth, fiber dimension and chemical composition. Positive impact of increased gibberellins on biochemical composition, fiber dimension and their derivative values were demonstrated in some lines of transgenic kenaf including increased cellulose content (91%), fiber length and quality but it still requires further study to confirm the critical level of this particular bioactive GA in transgenic plants. PMID:26175614

  16. Folk Epidemiology Recorded in Palm Leaf Manuscripts of Laos

    PubMed Central

    Elkington, Bethany G.; Sydara, Kongmany; Hartmann, John F.; Southavong, Bounhong; Soejarto, D. Doel

    2013-01-01

    In an effort to preserve traditional medicine knowledge and to uncover information about disease patterns and treatment in the Lao People’s Democratic Republic (PDR), linguistic experts have scanned centuries-old medical palm leaf manuscripts for disease entries. A list of more than 7000 diseases has resulted, shedding valuable light onto the medical history and traditional medicine heritage of the people of Laos, as well as providing an index for faster research into specific diseases and their traditional treatments. PMID:23847746

  17. Substrate specificity of THCA-CoA oxidases from rat liver light mitochondrial fractions on dehydrogenation of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid CoA thioester.

    PubMed

    Ikegawa, S; Goto, T; Mano, N; Goto, J

    1998-11-01

    The substrate specificity of rat liver peroxisomal 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoyl-CoA (THCA-CoA) oxidases, which catalyze the dehydrogenation of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid (THCA) CoA thioester, having an asymmetric center at C-25, to form (24E)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholest-24-enoic acid (delta 24-THCA) CoA thioester, was studied. The stable isotope labeled substrates, [3,7,12-18O3]-(25R)- and (25S)-THCA CoA thioesters were synthesized by an exchange reaction of carbonyl oxygens on a steroid nucleus of 3,7,12-trioxo-5 beta-cholestanoic acid, followed by metal hydride reduction and condensation reaction with CoA. After incubation of a mixture of unlabeled (25R)- and 18O-labeled (25S)-THCA CoA thioester, or vice versa, with hepatic peroxisomal THCA-CoA oxidases, biotransformed delta 24-THCA was determined by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry. The delta 24-THCA was derived only from (25S)-THCA CoA thioester, indicating that the 25S epimer of THCA is a preferential substrate on dehydrogenation by THCA-CoA oxidases.

  18. Searching for cognitive enhancement in the Morris water maze: better and worse performance in D-amino acid oxidase knockout (Dao(-/-)) mice.

    PubMed

    Pritchett, David; Taylor, Amy M; Barkus, Christopher; Engle, Sandra J; Brandon, Nicholas J; Sharp, Trevor; Foster, Russell G; Harrison, Paul J; Peirson, Stuart N; Bannerman, David M

    2016-04-01

    A common strategy when searching for cognitive-enhancing drugs has been to target the N-methyl-d-aspartate receptor (NMDAR), given its putative role in synaptic plasticity and learning. Evidence in favour of this approach has come primarily from studies with rodents using behavioural assays like the Morris water maze. D-amino acid oxidase (DAO) degrades neutral D-amino acids such as D-serine, the primary endogenous co-agonist acting at the glycine site of the synaptic NMDAR. Inhibiting DAO could therefore provide an effective and viable means of enhancing cognition, particularly in disorders like schizophrenia, in which NMDAR hypofunction is implicated. Indirect support for this notion comes from the enhanced hippocampal long-term potentiation and facilitated water maze acquisition of ddY/Dao(-) mice, which lack DAO activity due to a point mutation in the gene. Here, in Dao knockout (Dao(-/-) ) mice, we report both better and worse water maze performance, depending on the radial distance of the hidden platform from the side wall of the pool. Dao(-/-) mice displayed an increased innate preference for swimming in the periphery of the maze (possibly due to heightened anxiety), which facilitated the discovery of a peripherally located platform, but delayed the discovery of a centrally located platform. By contrast, Dao(-/-) mice exhibited normal performance in two alternative assays of long-term spatial memory: the appetitive and aversive Y-maze reference memory tasks. Taken together, these results question the proposed relationship between DAO inactivation and enhanced long-term associative spatial memory. They also have generic implications for how Morris water maze studies are performed and interpreted.

  19. An amperometric enzyme electrode and its biofuel cell based on a glucose oxidase-poly(3-anilineboronic acid)-Pd nanoparticles bionanocomposite for glucose biosensing.

    PubMed

    Sun, Lingen; Ma, Yixuan; Zhang, Pei; Chao, Long; Huang, Ting; Xie, Qingji; Chen, Chao; Yao, Shouzhuo

    2015-06-01

    A new amperometric enzyme electrode and its biofuel cell were fabricated based on a glucose oxidase (GOx)-poly(3-anilineboronic acid) (PABA)-Pd nanoparticles (PdNPs) bionanocomposite for biosensing of glucose. Briefly, Pd was electroplated on a multiwalled carbon nanotubes (MWCNTs)-modified Au electrode, and the GOx-PABA-PdNPs bionanocomposite was prepared on the Pd(plate)/MWCNTs/Au electrode through the chemical oxidation of a GOx-3-anilineboronic acid adduct by Na2PdCl4, followed by electrode-modification with an outer-layer chitosan (CS) film. The thus-prepared CS/GOx-PABA-PdNPs/Pd(plate)/MWCNTs/Au electrode exhibited a linear amperometric response to glucose concentration from 2.0 μM to 4.5 mM with a sensitivity of 160 μA/mM/cm(2), sub-μM detection limit, and excellent operation/storage stability in the first-generation biosensing mode, as well as excellent analytical performance in the second-generation biosensing mode. The good recoveries of glucose obtained from spiked urine samples revealed the application potential of our amperometric enzyme electrode. In addition, a glucose/O2 biofuel cell was constructed using this enzyme electrode as the anode and a Pt/MWCNTs/Au electrode as the cathode, and this biofuel cell as a self-powered biosensing device showed a linear voltage response to glucose concentration from 100 μM to 13.5 mM with a sensitivity of 43.5 mV/mM/cm(2) and excellent operation/storage stability.

  20. Non-equivalent conformations of D-amino acid oxidase dimer from porcine kidney between the two subunits. Molecular dynamics simulation and photoinduced electron transfer.

    PubMed

    Nueangaudom, Arthit; Lugsanangarm, Kiattisak; Pianwanit, Somsak; Kokpol, Sirirat; Nunthaboot, Nadtanet; Tanaka, Fumio

    2014-02-07

    The structural difference between two subunits of D-amino acid oxidase dimer from porcine kidney was studied by molecular dynamics simulation (MDS) and rate of photoinduced electron transfer (ET) from aromatic amino acids as tyrosines (Tyr) and tryptophanes (Trp) to the excited isoalloxazine (Iso*). The donor-acceptor distances (Rc) between isoalloxazine (Iso) and the donors were shortest in Tyr224 (0.74 nm) in Sub A at 10 °C (Sub A10), in Tyr224 (0.79 nm) in Sub B at 10 °C (Sub B10), in Tyr228 (0.85 nm) in Sub A at 30 °C (Sub A30), and in Tyr224 (0.72 nm) in Sub B at 30 °C (Sub B30). The Rcs were mostly shorter in the dimer than those in the monomer. Hydrogen bonding (H-bond) pairs between Iso and surrounding amino acids varied with the subunit and temperature. O2 of the Iso ring formed an H-bond exclusively with Thr317OG1 (side chain) in both Sub A10 and Sub A30, while it formed with Gly315N (peptide), Leu316N and Thr317N in Sub B10 and Sub B30. N3H of Iso formed an H-bond with Leu51O (peptide) in Sub A10 and Sub A30, but not in Sub B10 and Sub B30. Electron affinity of Iso* was appreciably lower in Sub A10 compared to Sub B10, while it was opposite at 30 °C. ET rate to Iso* was fastest from Tyr224 in Sub A10, while it was fastest from Tyr314 in Sub B10. The ET rate was fastest from Tyr314 in Sub A30, while it was fastest from Tyr224 in Sub B30. The greater ET rates in the dimer as compared to those in the monomer were elucidated with shorter Rc in the dimer as compared to the monomer. The static dielectric constants inside the subunits and the static dielectric constant between Iso and Tyr224 or Tyr228 were not different appreciably. A few water molecules and sometimes an amino acid were located between Iso and Tyr224, which may be the reason why the dielectric constant of the entire subunits did not differ from that between Iso and Tyr224.

  1. Feeding regime and management of local Lao pigs in Central Lao PDR.

    PubMed

    Chittavong, Malavanh; Lindberg, Jan Erik; Jansson, Anna

    2013-01-01

    A survey was carried out in smallholder farming systems in the districts of Borrikun, Khamkeuth, and Pakkading, in central Lao People's Democratic Republic, to assess the feeding regime and health status of local Lao pigs. In total, 216 farmers, 72 in each district, were interviewed using a questionnaire. Feed samples were collected for nutrient analysis and pen soil samples for mineral content determination. Farmers kept sows of native breeds such as Moo Lath, Moo Chid, and Moo Hmong. The number of sows per household was low (1.1 ± 0.1, 1.1 ± 0.1, and 1.2 ± 0.1 in Borrikun, Khamkeuth, and Pakkading, respectively) and pigs were mainly fed with rice bran and fresh cassava roots. Daily protein and mineral (Calcium, phosphorus, potassium, and sodium) allowances were lower than requirements. In all districts, the number of piglets at birth was around seven and pre-weaning piglet mortality was around 20 %. The most common causes of piglet death, before weaning, were diarrhea, runts, and squashed piglets. Most piglets were weaned after 4 months of age, but in the Borrikun and Pakkading districts, 11-16 % of households were weaned at <4 months. In all districts, pig management was mainly women's responsibility (around 90 %) and most farmers spent less than 1 h per day on pig management. A feasible and cheap way to increase nutrient supply to local pigs in central Lao People's Democratic Republic would be to include more fresh plant material (e.g., thick head, taro) and salt in the diet. Information and education on improving pig management should be targeted towards women.

  2. Respiratory illness healthcare-seeking behavior assessment in the Lao People’s Democratic Republic (Laos)

    PubMed Central

    2013-01-01

    Background Respiratory illness (RI) remains a public health problem in Laos, but little is known about the overall burden and people’s healthcare-seeking behavior for RI. Understanding the burden of RI and community patterns of healthcare-seeking behavior would provide better guidance for Lao public health program and policy planners to improve RI public health practice, surveillance systems, and prevention strategies. Methods A quantitative and qualitative survey was conducted in 14 randomly selected villages of two purposively selected peri-urban and two rural provinces in Laos. A pre-designed and pre-tested questionnaire was used to collect information on RI in household members (defined as new fever with cough and/or sore-throat in the absence of other diagnoses during the preceding 30 days) from all heads of household in each village. Sixteen focus group discussions were conducted to obtain more information to support the quantitative survey. Results Among 1,751 households (9,114 people) studied, 3.5% (317/9,114) had experienced RI (fever, cough, and/or sore-throat) in the 30 days before the survey [6.2% in rural and 2.4% in peri-urban areas (p<0.001)]. The percentage of RI among persons aged ≥15 years was 2.7%, 3.7% for those aged 5 – 14 years, and 8.2% for children < 5 years (p<0.001). Of all sick persons, 71% sought treatment [94% in peri-urban and 48% in rural areas (p<0.001)] and 31.5% of them self-medicated [55.5% in peri-urban and 29% in rural areas (p<0.001)]. Sick people in peri-urban areas preferred to chose private clinics and pharmacies as their first treatment option while in rural areas they frequently consulted with village health volunteers and visited health centres as their first choice. The qualitative study suggests that distance, costs of care, and service availability are the most important determinants of seeking healthcare. Conclusions The RI burden and healthcare-seeking behavior are different between rural and peri-urban areas

  3. Kinetic and mutagenic evidence for the role of histidine residues in the Lycopersicon esculentum 1-aminocyclopropane-1-carboxylic acid oxidase.

    PubMed

    Tayeh, M A; Howe, D L; Salleh, H M; Sheflyan, G Y; Son, J K; Woodard, R W

    1999-01-01

    The ACCO gene from Lycopersicon esculentum (tomato) has been cloned into the expression vector PT7-7. The highly expressed protein was recovered in the form of inclusion bodies. ACCO is inactivated by diethyl pyrocarbonate (DEPC) with a second-order rate constant of 170 M(-1) min(-1). The pH-inactivation rate data imply the involvement of an amino acid residue with a pK value of 6.05. The difference UV spectrum of the the DEPC-inactivated versus native ACCO showed a single peak at 242 nm indicating the modification of histidine residues. The inactivation was reversed by the addition of hydroxylamine to the DEPC-inactivated ACCO. Substrate/cofactor protection studies indicate that both iron and ACC bind near the active site, which contains histidine residues. Four histidines of ACCO were individually mutated to alanine and glycine. H39A is catalytically active, while H177A, H177G, H211A, H211G, H234A, and H234G are basically inactive. The results indicate that histidine residues 177, 211, and 234 may serve as ligands for the active-site iron of ACCO and/or may play some important structural or catalytic role.

  4. The effect of high polyphenol oxidase grass silage on metabolism of polyunsaturated fatty acids and nitrogen across the rumen of beef steers.

    PubMed

    Lee, M R F; Theobald, V J; Gordon, N; Leyland, M; Tweed, J K S; Fychan, R; Scollan, N D

    2014-11-01

    Polyphenol oxidase (PPO) activity in red clover (Trifolium pratense) has been reported to reduce both proteolysis and lipolysis, resulting in greater N use efficiency and protection of PUFA across the rumen. Although high levels of PPO have been reported in grasses such as cocksfoot (orchard grass; Dactylis glomerata), no in vivo research has determined whether grass PPO elicits the same response as red clover PPO. To test the hypothesis that silage ensiled from grass with high levels of PPO protects N and PUFA across the rumen, 6 steers with ruminal and duodenal cannulas were offered cocksfoot silage (CO; high-PPO grass), perennial ryegrass silage (PR; Lolium perenne; low-PPO grass), or red clover silage (RC; high-PPO control) at 16 g DM/kg BW daily with the experiment consisting of two 3 × 3 Latin squares with 21-d periods, consisting of 12 d of diet adaptation, 6 d of duodenal marker infusion, 2 d of duodenal sampling, and 1 d of ruminal sampling. All silages were well preserved, with DM of 34.4, 55.3, and 45.4% for CO, PR, and RC. Activity of PPO in silages was low due to deactivation but was greater in CO than either PR or RC (0.15 vs. 0.05 and 0.08 μkatal/g DM). Protein-bound phenol (mg/g DM) as a measure of the degree of oxidation and an indication of PPO protection was greatest for RC (15.9) but comparable for PR (10.1) and CO (12.2). Biohydrogenation of C18 PUFA was significantly lower on RC compared to the 2 grass silages with CO greater than PR. Despite lower levels of total fatty acid intake and subsequent duodenal flow, CO resulted in greater levels of phytanic acid and total branched and odd chain fatty acids in duodenal digesta than RC or PR. Ruminal ammonia concentration was greatest for RC, with no difference between the grasses. Duodenal flow of microbial N and efficiency of microbial protein synthesis were lowest for CO and comparable for RC and PR. The CO (high-grass PPO) did not result in elevated levels of C18 PUFA escaping the rumen or

  5. Promoter analyses and transcriptional profiling of eggplant polyphenol oxidase 1 gene (SmePPO1) reveal differential response to exogenous methyl jasmonate and salicylic acid.

    PubMed

    Shetty, Santoshkumar M; Chandrashekar, Arun; Venkatesh, Yeldur P

    2012-05-01

    The transcriptional regulation of multigenic eggplant (Solanum melongena) polyphenol oxidase genes (SmePPO) is orchestrated by their corresponding promoters which mediate developmentally regulated expression in response to myriad biotic and abiotic factors. However, information on structural features of SmePPO promoters and modulation of their expression by plant defense signals are lacking. In the present study, SmePPOPROMOTERs were cloned by genome walking, and their transcription start sites (TSS) were determined by RLM-RACE. Extensive sequence analyses revealed the presence of evolutionarily conserved and over-represented putative cis-acting elements involved in light-regulated transcription, biosynthetic pathways (phenylpropanoid/flavonoid), hormone signaling (abscisic acid, gibberellic acid, jasmonate and salicylate), elicitor and stress responses (cold/dehydration responses), sugar metabolism and plant defense signaling (W-BOX/WRKY) that are common to SmePPOPROMOTER1 and 2. The TSS for SmePPO genes are located 9-15bp upstream of ATG with variable lengths of 5' untranslated regions. Transcriptional profiling of SmePPOs in eggplant seedlings has indicated differential response to methyl jasmonate (MeJA) or salicylic acid (SA) treatment. In planta, while MeJA elicited expression of all the six SmePPOs, SA was only able to induce the expression of SmePPO4-6. Interestingly, in dual treatment, SA considerably repressed the MeJA-induced expression of SmePPOs. Functional dissection of SmePPOPROMOTER1 by deletion analyses using Agrobacterium-mediated transient expression in tobacco leaves has shown that MeJA enhances the SmePPOPROMOTER1-β-glucuronidase (GUS) expression in vivo, while SA does not. Histochemical and quantitative GUS assays have also indicated the negative effect of SA on MeJA-induced expression of SmePPOPROMOTER1. By combining in silico analyses, transcriptional profiling and expression of SmePPOPROMOTER1-GUS fusions, the role of SA on the modulation

  6. A Penicillium expansum glucose oxidase-encoding gene, GOX2, is essential for gluconic acid production and acidification during colonization of deciduous fruit.

    PubMed

    Barad, Shiri; Horowitz, Sigal Brown; Moscovitz, Oren; Lichter, Amnon; Sherman, Amir; Prusky, Dov

    2012-06-01

    Penicillium expansum, the causal agent of blue mold rot, causes severe postharvest maceration of fruit through secretion of total, d-gluconic acid (GLA). Two P. expansum glucose oxidase (GOX)-encoding genes, GOX1 and GOX2, were analyzed. GOX activity and GLA accumulation were strongly related to GOX2 expression, which increased with pH to a maximum at pH 7.0, whereas GOX1 was expressed at pH 4.0, where no GOX activity or extracellular GLA were detected. This differential expression was also observed at the leading edge of the decaying tissue, where GOX2 expression was dominant. The roles of the GOX genes in pathogenicity were further studied through i) development of P. expansum goxRNAi mutants exhibiting differential downregulation of GOX2, ii) heterologous expression of the P. expansum GOX2 gene in the nondeciduous fruit-pathogen P. chrysogenum, and iii) modulation of GLA production by FeSO(4) chelation. Interestingly, in P. expansum, pH and GLA production elicited opposite effects on germination and biomass accumulation: 26% of spores germinated at pH 7.0 when GOX activity and GLA were highest whereas, in P. chrysogenum at the same pH, when GLA did not accumulate, 72% of spores germinated. Moreover, heterologous expression of P. expansum GOX2 in P. chrysogenum resulted in enhanced GLA production and reduced germination, suggesting negative regulation of spore germination and GLA production. These results demonstrate that pH modulation, mediated by GLA accumulation, is an important factor in generating the initial signal or signals for fungal development leading to host-tissue colonization by P. expansum.

  7. Effect of endogenous ascorbic acid oxidase activity and stability on vitamin C in carrots (Daucus carota subsp. sativus) during thermal treatment.

    PubMed

    Leong, Sze Ying; Oey, Indrawati

    2012-10-15

    The purpose of this research was to study the effect of endogenous ascorbic acid oxidase (AAO) on vitamin C in carrots (Daucus carota subsp. sativus), namely Nantes, Egmont Gold and baby carrots during thermal treatment. Enzyme-substrate reaction kinetics of AAO were described using Michaelis-Menten equation. The estimated K(m) and V(max) values of AAO ranged from 50.34 to 63.54 μM and 23.70 to 26.82 μmol/min, respectively. Nantes carrots had the lowest AAO activity. On the other hand, Egmont Gold had the highest V(max). AAO activity in all carrot cultivars was stable up to 50 °C and inactivated above 50 °C. Irreversible thermal inactivation of AAO followed first order kinetics (55-70 °C) and the estimated activation energy of the three carrot cultivars situated between 114.33 and 191.45 kJ/mol. Regarding vitamin C stability, thermal treatment at 60-70 °C has resulted in total conversion of l-AA to DHAA due to residual AAO activity; a complete AAO inactivation was found in 80 °C-treated carrots with high vitamin C retention predominantly in l-AA form, up to 90%. On average, the carrots had a total vitamin C content amounting from 368.24 to 379.87 μg/g dry matter and the Nantes carrots had the highest vitamin C content. The effectiveness of rapid inactivation of endogenous AAO via heating (>80 °C, 10 min) prior to matrix disruption gave protection to l-AA towards enzymatic oxidation, thus resulted in a higher vitamin C content and stability in carrots.

  8. Evidence for association and epistasis at the DAOA/G30 and D-amino acid oxidase loci in an Irish schizophrenia sample.

    PubMed

    Corvin, A; McGhee, K A; Murphy, K; Donohoe, G; Nangle, J M; Schwaiger, S; Kenny, N; Clarke, S; Meagher, D; Quinn, J; Scully, P; Baldwin, P; Browne, D; Walsh, C; Waddington, J L; Morris, D W; Gill, M

    2007-10-05

    The D-amino acid oxidase (DAO) signaling pathway has been implicated in schizophrenia pathogenesis. This may be mediated through modulation of NMDA function by DAO, which is in turn activated by DAO activator (DAOA, formerly G72). Chumakov et al. (2002); PNAS 99: 13675-13680, identifying the novel schizophrenia susceptibility gene DAOA/G30 and a number of independent studies have since reported evidence of association between the DAOA and DAO genes and schizophrenia. However, at least two studies have failed to replicate the epistatic interaction between these loci described in the original report and there have been differences in the associated alleles/haplotypes reported at each locus. In this study, we performed association and epistasis analyses of the DAOA/G30 and DAO loci in a sample of 373 cases with DSM-IV schizophrenia/schizoaffective disorder and 812 controls from the Republic of Ireland. Corrected for the number of tests performed, we found evidence for association between markers at both genes and schizophrenia: DAOA/G30 (P = 0.005, OR = 1.34 (1.09, 1.65)) and DAO (P = 0.003, OR = 1.43 (1.12, 1.84). The data suggest that evidence for association at DAO (marker rs2111902) is more consistent than previously realized, particularly in Caucasian schizophrenia populations. We identified evidence for epistatic interaction between the associated SNPs at DAOA and DAO genes in contributing to schizophrenia risk (OR = 9.3 (1.4, 60.5). Based on these data, more systematic investigation of genes involved in DAO signaling is required.

  9. Effect of pulsed electric field treatment on enzyme kinetics and thermostability of endogenous ascorbic acid oxidase in carrots (Daucus carota cv. Nantes).

    PubMed

    Leong, Sze Ying; Oey, Indrawati

    2014-03-01

    The objective of this research was to study the enzyme kinetics and thermostability of endogenous ascorbic acid oxidase (AAO) in carrot purée (Daucus carota cv. Nantes) after being treated with pulsed electric field (PEF) processing. Various PEF treatments using electric field strength between 0.2 and 1.2kV/cm and pulsed electrical energy between 1 and 520kJ/kg were conducted. The enzyme kinetics and the kinetics of AAO thermal inactivation (55-70°C) were described using Michaelis-Menten model and first order reaction model, respectively. Overall, the estimated Vmax and KM values were situated in the same order of magnitude as the untreated carrot purée after being exposed to pulsed electrical energy between 1 and 400kJ/kg, but slightly changed at pulsed electrical energy above 500kJ/kg. However, AAO presented different thermostability depending on the electric field strength applied. After PEF treatment at the electric field strength between 0.2 and 0.5kV/cm, AAO became thermolabile (i.e. increase in inactivation rate (k value) at reference temperature) but the temperature dependence of k value (Ea value) for AAO inactivation in carrot purée decreased, indicating that the changes in k values were less temperature dependent. It is obvious that PEF treatment affects the temperature stability of endogenous AAO. The changes in enzyme kinetics and thermostability of AAO in carrot purée could be related to the resulting carrot purée composition, alteration in intracellular environment and the effective concentration of AAO released after being subjected to PEF treatment.

  10. An integrated bienzyme glucose oxidase-fructose dehydrogenase-tetrathiafulvalene-3-mercaptopropionic acid-gold electrode for the simultaneous determination of glucose and fructose.

    PubMed

    Campuzano, Susana; Loaiza, Oscar A; Pedrero, María; de Villena, F Javier Manuel; Pingarrón, José M

    2004-06-01

    A bienzyme biosensor for the simultaneous determination of glucose and fructose was developed by coimmobilising glucose oxidase (GOD), fructose dehydrogenase (FDH), and the mediator, tetrathiafulvalene (TTF), by cross-linking with glutaraldehyde atop a 3-mercaptopropionic acid (MPA) self-assembled monolayer (SAM) on a gold disk electrode (AuE). The performance of this bienzyme electrode under batch and flow injection (FI) conditions, as well as an amperometric detection in high-performance liquid chromatography (HPLC), are reported. The order of enzyme immobilisation atop the MPA-SAM affected the biosensor amperometric response in terms of sensitivity, with the immobilisation order GOD, FDH, TTF being selected. Similar analytical characteristics to those obtained with single GOD or FDH SAM-based biosensors for glucose and fructose were achieved with the bienzyme electrode, indicating that no noticeable changes in the biosensor responses to the analytes occurred as a consequence of the coimmobilisation of both enzymes on the same MPA-AuE. The suitability of the bienzyme biosensor for the analysis of real samples under flow injection conditions was tested by determining glucose in two certified serum samples. The simultaneous determination of glucose and fructose in the same sample cannot be performed without a separation step because at the detection potential used (+0.10 V), both sugars show amperometric response. Consequently, HPLC with amperometric detection at the TTF-FDH-GOD-MPA-AuE was accomplished. Glucose and fructose were simultaneously determined in honey, cola softdrink, and commercial apple juice, and the results were compared with those obtained by using other reference methods.

  11. Antibacterial action of a heat-stable form of L-amino acid oxidase isolated from king cobra (Ophiophagus hannah) venom.

    PubMed

    Lee, Mui Li; Tan, Nget Hong; Fung, Shin Yee; Sekaran, Shamala Devi

    2011-03-01

    The major l-amino acid oxidase (LAAO, EC 1.4.3.2) of king cobra (Ophiophagus hannah) venom is known to be an unusual form of snake venom LAAO as it possesses unique structural features and unusual thermal stability. The antibacterial effects of king cobra venom LAAO were tested against several strains of clinical isolates including Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli using broth microdilution assay. For comparison, the antibacterial effects of several antibiotics (cefotaxime, kanamycin, tetracycline, vancomycin and penicillin) were also examined using the same conditions. King cobra venom LAAO was very effective in inhibiting the two Gram-positive bacteria (S. aureus and S. epidermidis) tested, with minimum inhibitory concentration (MIC) of 0.78μg/mL (0.006μM) and 1.56μg/mL (0.012μM) against S. aureus and S. epidermidis, respectively. The MICs are comparable to the MICs of the antibiotics tested, on a weight basis. However, the LAAO was only moderately effective against three Gram-negative bacteria tested (P. aeruginosa, K. pneumoniae and E. coli), with MIC ranges from 25 to 50μg/mL (0.2-0.4μM). Catalase at the concentration of 1mg/mL abolished the antibacterial effect of LAAO, indicating that the antibacterial effect of the enzyme involves generation of hydrogen peroxide. Binding studies indicated that king cobra venom LAAO binds strongly to the Gram-positive S. aureus and S. epidermidis, but less strongly to the Gram-negative E. coli and P. aeruginosa, indicating that specific binding to bacteria is important for the potent antibacterial activity of the enzyme.

  12. Dissecting the role of climacteric ethylene in kiwifruit (Actinidia chinensis) ripening using a 1-aminocyclopropane-1-carboxylic acid oxidase knockdown line.

    PubMed

    Atkinson, Ross G; Gunaseelan, Kularajathevan; Wang, Mindy Y; Luo, Luke; Wang, Tianchi; Norling, Cara L; Johnston, Sarah L; Maddumage, Ratnasiri; Schröder, Roswitha; Schaffer, Robert J

    2011-07-01

    During climacteric fruit ripening, autocatalytic (Type II) ethylene production initiates a transcriptional cascade that controls the production of many important fruit quality traits including flavour production and softening. The last step in ethylene biosynthesis is the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene by the enzyme ACC oxidase (ACO). Ten independent kiwifruit (Actinidia chinensis) lines were generated targeting suppression of fruit ripening-related ACO genes and the fruit from one of these lines (TK2) did not produce detectable levels of climacteric ethylene. Ripening behaviour in a population of kiwifruit at harvest is asynchronous, so a short burst of exogenous ethylene was used to synchronize ripening in TK2 and control fruit. Following such a treatment, TK2 and control fruit softened to an 'eating-ripe' firmness. Control fruit produced climacteric ethylene and softened beyond eating-ripe by 5 d. In contrast, TK2 fruit maintained an eating-ripe firmness for >25 d and total volatile production was dramatically reduced. Application of continuous exogenous ethylene to the ripening-arrested TK2 fruit re-initiated fruit softening and typical ripe fruit volatiles were detected. A 17 500 gene microarray identified 401 genes that changed after ethylene treatment, including a polygalacturonase and a pectate lyase involved in cell wall breakdown, and a quinone oxidoreductase potentially involved in volatile production. Many of the gene changes were consistent with the softening and flavour changes observed after ethylene treatment. However, a surprisingly large number of genes of unknown function were also observed, which could account for the unique flavour and textural properties of ripe kiwifruit.

  13. Comparative study on functionalized SBA-15 and SBA-16 nanostructured materials used for immobilization of D-amino acid oxidase

    NASA Astrophysics Data System (ADS)

    Hy, Le Gia; Phuong, Dang Tuyet; Yen, Hoang; Hoan, Nguyen Thi Vuong; Linh, Bui Thi Hai; Thang, Hoang vinh; Hoa, Tran Thi Kim; Thang, Dinh Cao; Nguyen, Vu Thi Hanh; Thao, Phan Thi Hong; Giap, Chu Van; Tuan, Vu Anh

    2008-12-01

    SBA-15 and SBA-16 nanostucrured materials were synthesized via hydrothermal treatment and were functionalized with 3-aminopropyltriethoxysilane (APTES), and vinyltriethoxysilane (VTES). The obtained samples were characterized by different techniques such as XRD, BET, IR and TEM. After functionalization, it showed that these nanostrucrured materials were still maintained the hexagonal pore structure of the parent SBA-15 and cubic cage structure of the parent SBA-16. The non-functionalized pure silica SBA-15 and SBA-16 as well as functionalized SBA-15 and SBA-16 materials were used to immobilize DAAO, which is industrially important enzyme for the production of glutaryl 7-amino cephalosporanic acid (GL-7-ACA) from cephalosporin C (CPC). The obtained results revealed that functionalized SBA- 15 and SBA-16 materials exhibited higher enzymatic activity and stability than those of non-functionalized ones. This might be due to the enhancing of surface hydrophobicity upon functionalization. The surface functionalization of the nanostructured silicas with organic groups can enhance the interaction between enzyme and the supports and consequently increasing the operational stability of the immobilized enzyme. The loading of enzyme on SBA-15 materials was higher than that on SBA-16 samples (both functionalized and non-functionalized types). This might be explained by the difference in pore size and type (cylindrical for SBA-15 and bottle-neck for SBA-16) as well as structure shape (hexagonal for SBA-15 and cubic cage for SBA-16) of both mesoporous materials. Additionally, nature of functionalized groups significantly affected the enzymatic activity. Effects on surface binding force, nature of functional groups, pore size of supports were investigated and discussed.

  14. Structural insights into sulfite oxidase deficiency.

    PubMed

    Karakas, Erkan; Wilson, Heather L; Graf, Tyler N; Xiang, Song; Jaramillo-Busquets, Sandra; Rajagopalan, K V; Kisker, Caroline

    2005-09-30

    Sulfite oxidase deficiency is a lethal genetic disease that results from defects either in the genes encoding proteins involved in molybdenum cofactor biosynthesis or in the sulfite oxidase gene itself. Several point mutations in the sulfite oxidase gene have been identified from patients suffering from this disease worldwide. Although detailed biochemical analyses have been carried out on these mutations, no structural data could be obtained because of problems in crystallizing recombinant human and rat sulfite oxidases and the failure to clone the chicken sulfite oxidase gene. We synthesized the gene for chicken sulfite oxidase de novo, working backward from the amino acid sequence of the native chicken liver enzyme by PCR amplification of a series of 72 overlapping primers. The recombinant protein displayed the characteristic absorption spectrum of sulfite oxidase and exhibited steady state and rapid kinetic parameters comparable with those of the tissue-derived enzyme. We solved the crystal structures of the wild type and the sulfite oxidase deficiency-causing R138Q (R160Q in humans) variant of recombinant chicken sulfite oxidase in the resting and sulfate-bound forms. Significant alterations in the substrate-binding pocket were detected in the structure of the mutant, and a comparison between the wild type and mutant protein revealed that the active site residue Arg-450 adopts different conformations in the presence and absence of bound sulfate. The size of the binding pocket is thereby considerably reduced, and its position relative to the cofactor is shifted, causing an increase in the distance of the sulfur atom of the bound sulfate to the molybdenum.

  15. Bioconversion of α-linolenic acid to n-3 LCPUFA and expression of PPAR-alpha, acyl Coenzyme A oxidase 1 and carnitine acyl transferase I are incremented after feeding rats with α-linolenic acid-rich oils.

    PubMed

    González-Mañán, Daniel; Tapia, Gladys; Gormaz, Juan Guillermo; D'Espessailles, Amanda; Espinosa, Alejandra; Masson, Lilia; Varela, Patricia; Valenzuela, Alfonso; Valenzuela, Rodrigo

    2012-07-01

    High dietary intake of n-6 fatty acids in relation to n-3 fatty acids may generate health disorders, such as cardiovascular and other chronic diseases. Fish consumption rich in n-3 fatty acids is low in Latin America, it being necessary to seek other alternatives to provide α-linolenic acid (ALA), precursor of n-3 LCPUFA (EPA and DHA). Two innovative oils were assayed, chia (Salvia hispanica) and rosa mosqueta (Rosa rubiginosa). This study evaluated hepatic bioconversion of ALA to EPA and DHA, expression of PPAR-α, acyl-Coenzyme A oxidase 1 (ACOX1) and carnitine acyltransferase I (CAT-I), and accumulation of EPA and DHA in plasma and adipose tissue in Sprague-Dawley rats. Three experimental groups were fed 21 days: sunflower oil (SFO, control); chia oil (CO); rosa mosqueta oil (RMO). Fatty acid composition of total lipids and phospholipids from plasma, hepatic and adipose tissue was assessed by gas-liquid chromatography and TLC. Expression of PPAR-α (RT-PCR) and ACOX1 and CAT-I (Western blot). CO and RMO increased plasma, hepatic and adipose tissue levels of ALA, EPA and DHA and decreased n-6:n-3 ratio compared to SFO (p < 0.05, One-way ANOVA and Newman-Keuls test). CO increased levels of ALA and EPA compared to RMO (p < 0.05). No significant differences were observed for DHA levels. CO also increased the expression of PPAR-α, ACOX1 and CAT-I. Only CAT-I levels were increased by RO. CO and RMO may be a nutritional alternative to provide ALA for its bioconversion to EPA and DHA, and to increase the expression of PPAR-α, ACOX1 and CAT-I, especially CO-oil.

  16. Epidemiology of Strongyloides stercoralis on Mekong islands in southern Laos.

    PubMed

    Vonghachack, Youthanavanh; Sayasone, Somphou; Bouakhasith, Dalouny; Taisayavong, Keoka; Akkavong, Kongsap; Odermatt, Peter

    2015-01-01

    Strongyloides stercoralis is a neglected helminth infection potentially that can lead to systemic infection in immunocompromised individuals. In Lao People's Democratic Republic (Lao PDR, Laos), information on S. stercoralis infection is scarce. We assessed S. stercoralis infection and associated risk factors and symptoms on the Mekong islands in Southern Laos. Baermann and Kato-Katz techniques were performed on two stool samples from each individual to detect S. stercoralis larvae and concomitant helminth infections. Among 729 individuals, 41.0% were infected with S. stercoralis. Men were at higher risk than women (OR 1.97, 95% CI 1.45-2.67). Urticaria and body itching was associated with S. stercoralis infection (OR 2.4, 95% CI 1.42-4.05). Infection with Opisthorchis viverrini (72.2%), Schistosoma mekongi (12.8%), and hookworm (56.1%) were very common. Few infections with Trichuris trichiura (3.3%), Ascaris lumbricoides (0.3%) and Taenia spp. (0.3%) were detected. The majority of helminth infections were of light intensity, with prevalences of 80.4%, 92.9%, 64.5%, 100% and 100%, for O. viverrini, hookworm, S. mekongi, T. trichiura and A. lumbricoides, respectively. Nevertheless, heavy infection intensities were observed for O. viverrini (1.0%), S. mekongi (14.0%) and hookworm (2.9%). S. stercoralis is highly endemic on the islands of Khong district, Champasack province, Southern Laos. The national helminth control programme should take action to control this helminth infection.

  17. Supplement for Curriculum Guide for Science: Lao-Speaking Students. Kindergarten-Grade 8. Working Draft.

    ERIC Educational Resources Information Center

    Chicago Board of Education, IL.

    This supplement to the Chicago public schools' science curriculum, for use with Lao-speaking students in grades K-8, is designed to help students make the transition to learning science in English. English-Lao vocabulary lists, independent learning activities and teaching aids (in both languages), and study questions (in Lao) are included to…

  18. Mass-Analyzed Threshold Ionization of LaO2

    NASA Astrophysics Data System (ADS)

    Wu, Lu; Zhang, Changhua; Krasnokutski, Sergiy; Yang, Dong-Sheng

    2010-06-01

    Lanthanum oxide, LaO2, is produced in a pulsed laser-vaporization metal-cluster source and studied by mass-analyzed threshold ionization (MATI) spectroscopy. From the MATI spectrum, the adiabatic ionization energy of LaO2 is determined to be 40134 (5) Cm-1 or 4.976 (6) eV, and La+-O stretching and O-La+-O bending frequencies are measured as 656 and 120 Cm-1. The measured ionization energy is about 3.0 eV lower than the value predicted by recent high-level ab initio calculations. In this talk, we will discuss the discrepancy between the experiment and theory and the electronic transition observed in our experiment. T. K. Todorova, I. Infante, L. Gagliardi, and J. M. Dyke, J. Phys. Chem. A 112, 7825 (2008).

  19. Nitro-oleic acid ameliorates oxygen and glucose deprivation/re-oxygenation triggered oxidative stress in renal tubular cells via activation of Nrf2 and suppression of NADPH oxidase.

    PubMed

    Nie, Huibin; Xue, Xia; Liu, Gang; Guan, Guangju; Liu, Haiying; Sun, Lina; Zhao, Long; Wang, Xueling; Chen, Zhixin

    2016-01-01

    Nitroalkene derivative of oleic acid (OA-NO2), due to its ability to mediate revisable Michael addition, has been demonstrated to have various biological properties and become a therapeutic agent in various diseases. Though its antioxidant properties have been reported in different models of acute kidney injury (AKI), the mechanism by which OA-NO2 attenuates intracellular oxidative stress is not well investigated. Here, we elucidated the anti-oxidative mechanism of OA-NO2 in an in vitro model of renal ischemia/reperfusion (I/R) injury. Human tubular epithelial cells were subjected to oxygen and glucose deprivation/re-oxygenation (OGD/R) injury. Pretreatment with OA-NO2 (1.25 μM, 45 min) attenuated OGD/R triggered reactive oxygen species (ROS) generation and subsequent mitochondrial membrane potential disruption. This action was mediated via up-regulating endogenous antioxidant defense components including superoxide dismutase (SOD1), heme oxygenase 1 (HO-1), and γ-glutamyl cysteine ligase modulatory subunits (GCLM). Moreover, subcellular fractionation analyses demonstrated that OA-NO2 promoted nuclear translocation of nuclear factor-E2- related factor-2 (Nrf2) and Nrf2 siRNA partially abrogated these protective effects. In addition, OA-NO2 inhibited NADPH oxidase activation and NADPH oxidase 4 (NOX4), NADPH oxidase 2 (NOX2) and p22(phox) up-regulation after OGD/R injury, which was not relevant to Nrf2. These results contribute to clarify that the mechanism of OA-NO2 reno-protection involves both inhibition of NADPH oxidase activity and induction of SOD1, Nrf2-dependent HO-1, and GCLM.

  20. Transport Properties of Exfoliated BSCCO on LAO/STO Heterostructures

    NASA Astrophysics Data System (ADS)

    Ujwary, Sylvia; Sutton, Erin; Gray, Mason; Burch, Kenneth; Levy, Jeremy

    We investigate the interaction between high-temperature superconductor Bi2SrCaCu2O8+δ (BSCCO) flakes deposited on the oxide heterostructure LaAlO3/SrTiO3 (LAO/STO). Conductive-atomic force microscope (c-AFM) lithography will be used to create nanowires at the LAO/STO interface that couple to the BSCCO. Through coupling of these materials, we will be able to study phenomena such as the proximity effect and coulomb drag. We gratefully acknowledge support from the NASA PA Space Grant Consortium (SU), and the National Science Foundation (Grant No. DMR-1410846).

  1. Activation of polyphenol oxidase of chloroplasts.

    PubMed

    Tolbert, N E

    1973-02-01

    Polyphenol oxidase of leaves is located mainly in chloroplasts isolated by differential or sucrose density gradient centrifugation. This activity is part of the lamellar structure that is not lost on repeated washing of the plastids. The oxidase activity was stable during prolonged storage of the particles at 4 C or -18 C. The Km (dihydroxyphenylalanine) for spinach leaf polyphenol oxidase was 7 mm by a spectrophotometric assay and 2 mm by the manometric assay. Polyphenol oxidase activity in the leaf peroxisomal fraction, after isopycnic centrifugation on a linear sucrose gradient, did not coincide with the peroxisomal enzymes but was attributed to proplastids at nearly the same specific density.Plants were grouped by the latency properties for polyphenol oxidase in their isolated chloroplasts. In a group including spinach, Swiss chard, and beet leaves the plastids immediately after preparation from fresh leaves required a small amount of light for maximal rates of oxidation of dihydroxyphenylalanine. Polyphenol oxidase activity in the dark or light increased many fold during aging of these chloroplasts for 1 to 5 days. Soluble polyphenol oxidase of the cytoplasm was not so stimulated. Chloroplasts prepared from stored leaves were also much more active than from fresh leaves. Maximum rates of dihydroxyphenylalanine oxidation were 2 to 6 mmoles x mg(-1) chlorophyll x hr(-1). Equal stimulation of latent polyphenol oxidase in fresh or aged chloroplasts in this group was obtained by either light, an aged trypsin digest, 3-(4-chlorophenyl)-1, 1-dimethylurea, or antimycin A. A variety of other treatments did not activate or had little effect on the oxidase, including various peptides, salts, detergents, and other proteolytic enzymes.Activation of latent polyphenol oxidase in spinach chloroplasts by trypsin amounted to as much as 30-fold. The trypsin activation occurred even after the trypsin had been treated with 10% trichloroacetic acid, 1.0 n HCl or boiled for 30

  2. Structural basis for the temperature-induced transition of D-amino acid oxidase from pig kidney revealed by molecular dynamic simulation and photo-induced electron transfer.

    PubMed

    Nueangaudom, Arthit; Lugsanangarm, Kiattisak; Pianwanit, Somsak; Kokpol, Sirirat; Nunthaboot, Nadtanet; Tanaka, Fumio

    2012-02-28

    The structural basis for the temperature-induced transition in the D-amino acid oxidase (DAAO) monomer from pig kidney was studied by means of molecular dynamic simulations (MDS). The center to center (Rc) distances between the isoalloxazine ring (Iso) and all aromatic amino acids (Trp and Tyr) were calculated at 10 °C and 30 °C. Rc was shortest in Tyr224 (0.82 and 0.88 nm at 10 and 30 °C, respectively), and then in Tyr228. Hydrogen bonding (H-bond) formed between the Iso N1 and Gly315 N (peptide), between the Iso N3H and Leu51 O (peptide) and between the Iso N5 and Ala49 N (peptide) at 10 °C, whilst no H-bond was formed at the Iso N1 and Iso N3H at 30 °C. The H-bond of Iso O4 with Leu51 N (peptide) at 10 °C switched to that with Ala49 N (peptide) at 30 °C. The reported fluorescence lifetimes (228 and 182 ps at 10 and 30 °C, respectively) of DAAO were analyzed with Kakitani and Mataga (KM) ET theory. The calculated fluorescence lifetimes displayed an excellent agreement with the observed lifetimes. The ET rate was fastest from Tyr224 to the excited Iso (Iso*) at 10 °C and from Tyr314 at 30 °C, despite the fact that the Rc was shortest between Iso and Tyr224 at both temperatures. This was explained by the electrostatic energy in the protein. The differences in the observed fluorescence lifetimes at 10 and 30 °C were ascribed to the differences in electron affinity of the Iso* at both temperatures, in which the free energies of the electron affinity of Iso* at 10 and 30 °C were -8.69 eV and -8.51 eV respectively. The other physical quantities related to ET did not differ appreciably at both temperatures. The electron affinities at both temperatures were calculated with a semi-empirical molecular orbital method (MO) of PM6. Mean calculated electron affinities over 100 snapshots with 0.1 ps intervals were -7.69 eV at 10 °C and -7.59 eV at 30 °C. The difference in the calculated electron affinities, -0.11 eV, was close to the observed difference in the

  3. Recollections of a Case Officer in Laos, 1962-1964

    DTIC Science & Technology

    2003-01-01

    some govern ment offices were clustered around what appeared to he a central square. My house was near the airport. which had a laterite runway...following the Lao side of the Mekong River. These roads all had crushed laterite surfaces, but none were reliable for year� round travel, primarily

  4. Bilingual Dictionary of Mathematical Terms: English-Lao.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Bureau of Bilingual Education.

    This dictionary was developed for use by Laotian junior high and high school students to assist them in their understanding of mathematics vocabulary and concepts in English. Terminology and definitions are included in English with Lao translations provided directly below each entry. Students may use this publication as a dictionary, a workbook,…

  5. Towards a Curriculum for the Thai Lao of Northeast Thailand?

    ERIC Educational Resources Information Center

    Draper, John

    2015-01-01

    This article considers a fundamental issue in language planning, namely, whether or not to introduce a curriculum for the mother tongue (MT), in the wider context of a complex language planning situation in Thailand. It details recent moves in the consideration of this issue for the Thai Lao (Isan) of Northeast Thailand, Thailand's largest…

  6. [Your New Life in the United States. Lao Edition.

    ERIC Educational Resources Information Center

    Center for Applied Linguistics, Washington, DC. Language and Orientation Resource Center.

    An illustrated guide to aspects of life in the United States is presented in Lao for recent Laotian arrivals. The guidelines address such topics as resettlement agencies, community relations and national customs, the U.S. government, local and long distance transport, mail and telephone communication systems, employment practices, the educational…

  7. The Peoples and Cultures of Cambodia, Laos, and Vietnam.

    ERIC Educational Resources Information Center

    Center for Applied Linguistics, Washington, DC. Language and Orientation Resource Center.

    A handbook for those involved in Southeast Asian refugee assistance discusses some of the values and customs that refugee groups from Cambodia, Laos, and Vietnam may have in common and looks at the different countries and peoples of the region. A section on the shared values and customs of Indochinese refugees focuses on aspects of family life,…

  8. The chemistry of escapin: identification and quantification of the components in the complex mixture generated by an L-amino acid oxidase in the defensive secretion of the sea snail Aplysia californica.

    PubMed

    Kamio, Michiya; Ko, Ko-Chun; Zheng, Shilong; Wang, Binghe; Collins, Stacy L; Gadda, Giovanni; Tai, Phang C; Derby, Charles D

    2009-01-01

    Escapin is an L-amino acid oxidase in the ink of a marine snail, the sea hare Aplysia californica, which oxidizes L-lysine (1) to produce a mixture of chemicals which is antipredatory and antimicrobial. The goal of our study was to determine the identity and relative abundance of the constituents of this mixture, using molecules generated enzymatically with escapin and also using products of organic syntheses. We examined this mixture under the natural range of pH values for ink-from approximately 5 at full strength to approximately 8 when fully diluted in sea water. The enzymatic reaction likely forms an equilibrium mixture containing the linear form alpha-keto-epsilon-aminocaproic acid (2), the cyclic imine Delta(1)-piperidine-2-carboxylic acid (3), the cyclic enamine Delta(2)-piperidine-2-carboxylic acid (4), possibly the linear enol 6-amino-2-hydroxy-hex-2-enoic acid (7), the alpha-dihydroxy acid 6-amino-2,2-dihydroxy-hexanoic acid (8), and the cyclic aminol 2-hydroxy-piperidine-2-carboxylic acid (9). Using NMR and mass spectroscopy, we show that 3 is the major component of this enzymatic product at any pH, but at more basic conditions, the equilibrium shifts to produce relatively more 4, and at acidic conditions, the equilibrium shifts to produce relatively more 2, 7, and/or 9. Studies of escapin's enzyme kinetics demonstrate that because of the high concentrations of escapin and L-lysine in the ink secretion, millimolar concentrations of 3, H(2)O(2), and ammonia are produced, and also lower concentrations of 2, 4, 7, and 9 as a result. We also show that reactions of this mixture with H(2)O(2) produce delta-aminovaleric acid (5) and delta-valerolactam (6), with 6 being the dominant component under the naturally acidic conditions of ink. Thus, the product of escapin's action on L-lysine contains an equilibrium mixture that is more complex than previously known for any L-amino acid oxidase.

  9. Culture-independent bacterial community analysis of the salty-fermented fish paste products of Thailand and Laos.

    PubMed

    Marui, Junichiro; Boulom, Sayvisene; Panthavee, Wanchai; Momma, Mari; Kusumoto, Ken-Ichi; Nakahara, Kazuhiko; Saito, Masayoshi

    2015-01-01

    A bacterial community analysis, using a culture-independent method (polymerase chain reaction-denaturing gradient gel electrophoresis), detected 17 species of bacteria including species of the genera Tetragenococcus, Lactobacillus, Pediococcus, Weissella Halanaerobium, Clostridium, and Sphingomonas in a traditional salty-fermented fish paste known as pla-ra or pa-daek in Thailand and Laos, which is used as a storage-stable multi-purpose seasoning. The representative genus of lactic acid bacteria seemed to vary in the 10 products collected from Thailand and Laos. Tetragenococci were common in products from central Thailand and Vientiane in Laos which had salinities of not less than 11% and pH values ranging from 5.6 to 6.1. However, lactobacilli were common in products from northern Thailand which had the lowest salinities (8.3-8.6%) and pH values (4.5-4.8) of all the samples examined. Two Lactobacillus and one Tetragenococcus species were detected in one product from northeastern Thailand containing 10% salt. These results suggest that salinity in pla-ra/pa-daek is an important determinant of the representative genus of lactic acid bacteria such as, Tetragenococcus or Lactobacillus. Additionally, differences in the acidity between these two groups seemed to be related to the production of d-/l-lactic acid in the lactic acid bacteria in each product. This is the first study to report a correlation between bacterial community structure and taste components in pla-ra/pa-daek products from various regions. This scientific work on a traditional fermented food will be useful in helping local producers meet differing consumer preferences in various regions.

  10. 5,5-Dithiobis(2-nitrobenzoic acid) pyrene derivative-carbon nanotube electrodes for NADH electrooxidation and oriented immobilization of multicopper oxidases for the development of glucose/O2 biofuel cells.

    PubMed

    Giroud, Fabien; Sawada, Koichi; Taya, Masahito; Cosnier, Serge

    2017-01-15

    We report the functionalization of multi-walled carbon nanotubes (MWCNTs) electrodes by a bifunctional nitroaromatic molecule accomplished via π-π interactions of a pyrene derivative. DTNB (5,5'-dithiobis(2-nitrobenzoic acid)) has the particularity to possess both electroactivable nitro groups and negatively charged carboxylic groups. The integration of the DTNB-modified MWCNTs was evaluated for different bioelectrocatalytic systems. The immobilized DTNB-based electrodes showed electrocatalytic activity toward the oxidation of the reduced form of nicotinamide adenine dinucleotide (NADH) with low overpotential of -0.09V vs Ag/AgCl at neutral pH. Glucose dehydrogenase was successfully immobilized at the surface of DTNB-based electrodes and, in the presence of NAD(+), the resulting bioelectrode achieved efficient glucose oxidation with high current densities of 2.03mAcm(-2). On the other hand, the aromatic structure and the negatively charged nature of the DTNB provoked orientation of both laccase and bilirubin oxidase onto the electrode, which enhanced their ability to undergo a direct electron transfer for oxygen reduction. Due to the proper orientation, low overpotentials were obtained (ca. 0.6V vs Ag/AgCl) and high electrocatalytic currents of about 3.5mAcm(-)(2) were recorded at neutral pH in O2 saturated conditions for bilirubin oxidase electrodes. The combination of these bioanodes and bilirubin oxidase biocathodes provided glucose/O2 enzymatic biofuel cells (EBFC) exhibiting an open-circuit potential of 0.640V, with an associated maximum current density of 2.10mAcm(-)(2). Moreover, the fuel cell delivered a maximum power density of 0.50mWcm(-)(2) at 0.36 V.

  11. Biological evaluation of plants of Laos used in the treatment of tuberculosis in Lao traditional medicine

    PubMed Central

    Elkington, Bethany G.; Southavong, Bounhong; Sydara, Kongmany; Souliya, Onevilay; Vanthanouvong, Manoluck; Nettavong, Kongdeuane; Thammachack, Bounleuth; Pak, Dennis H.; Riley, Mary C.; Franzblau, Scott G.; Soejarto, D. Doel

    2010-01-01

    Tuberculosis has existed in Southeast Asia for thousands of years. Many traditional treatments involve herbal remedies. Over time, these traditional treatments have had the chance to become refined based on efficacy and safety. It was therefore hypothesized that plants that were used in the past and are still used today to treat symptoms associated with tuberculosis are more likely to contain anti-tubercular compounds than plants that have not been used continuously. To try to deduce which plants were used in Laos in the past, a collection of palm leaf manuscripts was studied and a list of plants used to treat symptoms associated with tuberculosis was compiled. Interviews were then conducted with contemporary healers to see if the same plants are still being used today. Plants that were found in the manuscripts and/or are presently used by healers were collected, extracted and were evaluated in an anti-tubercular assay. This paper presents the methods used to identify and collect plants used to treat symptoms indicative of tuberculosis, and the results of anti-TB assays to test for activity. PMID:21479105

  12. Visual expression analysis of the responses of the alternative oxidase gene (aox1) to heat shock, oxidative, and osmotic stresses in conidia of citric acid-producing Aspergillus niger.

    PubMed

    Honda, Yuki; Hattori, Takasumi; Kirimura, Kohtaro

    2012-03-01

    The citric acid-producing filamentous fungus Aspergillus niger WU-2223L shows cyanide-insensitive respiration catalyzed by alternative oxidase in addition to the cytochrome pathway. Sequence analysis of the 5' flanking region of the alternative oxidase gene (aox1) revealed a potential heat shock element (HSE) and a stress response element (STRE). We have previously confirmed aox1 expression in conidia. In this study, to confirm whether the upstream region of aox1 responds to various stresses, we used a visual expression analysis system for single-cell conidia of the A. niger strain AOXEGFP-1. This strain harbored a fusion gene comprising aox1 and egfp, which encodes the enhanced green fluorescent protein (EGFP). The fluorescence intensity of EGFP increased in conidia of A. niger AOXEGFP-1 that were subjected to heat shock at 35-45 °C, oxidative stress by exposure to 5mM paraquat or 1 mM t-butylhydroperoxide, or osmotic stresses by exposure to 0.5 M KCl or 1.0 M mannitol. These results indicate that the putative HSE and STRE in the upstream region of aox1 directly or indirectly respond to heat shock, oxidative, and osmotic stresses.

  13. Current status of human taeniasis in Lao People's Democratic Republic.

    PubMed

    Jeon, Hyeong-Kyu; Yong, Tai-Soon; Sohn, Woon-Mok; Chai, Jong-Yil; Min, Duk-Young; Yun, Cheong-Ha; Rim, Han-Jong; Pongvongsa, Tiengkham; Banouvong, Virasack; Insisiengmay, Bounnaloth; Phommasack, Bounlay; Eom, Keeseon S

    2013-04-01

    Human taeniasis was investigated in Lao People's Democratic Republic (Lao PDR) between 2000 and 2011 as part of the nation's helminthiasis survey. A total of 55,038 inhabitants, including 29,846 school children, were examined using the Kato-Katz and scotch-tape anal swab method, and morphological observation of adult worms. Molecular identification of Taenia tapeworms was performed by multiplex PCR or DNA sequence analysis of the mitochondrial cox1 gene. Taenia eggs were present at a rate of 1.5% (845/55,038) in the subject population. Adult tapeworms were identified as T. solium or T. saginata by analyzing the collectable stool specimens (n=126). Three specimens identified as T. solium were found in Luang Prabang, while the remaining 123 specimens, which were T. saginata, were found in Bokeo, Bolikhamxay, Champasak, Houaphan, Khammouane, Luang Namta, Luang Prabang, Oudomxay, Phongsaly, Saysomboune, Saravane, Savannakhet, Xayaboury, Xekong, Xieng Khouang Province, and Vientiane Municipality.

  14. Defining and redefining harm reduction in the Lao context

    PubMed Central

    2012-01-01

    The response to drug use in Laos has focused on reducing opium supply (supply reduction) and rates of drug use (demand reduction). However, recently there is increased interest among government counterparts to discuss and develop broader responses to injecting drug use (IDU) including the introduction of harm reduction programs. The concept of harm reduction has just been introduced to Lao PDR and as yet there is no agreement on a definition of the concept. We highlight here a range of issues that remain controversial in Lao PDR in the HIV, drug use and harm reduction discourse, the definition of 'harm reduction' and related terms; and the scope of harm reduction. This was a qualitative study, consisting of in-depth interviews with 27 law enforcement and 8 health officers who work in the fields of HIV and/or drug control about their understanding of HIV related to drug use, and concepts of harm reduction. Content analysis was performed to identify the coding, categories and themes. We found that law enforcement officers in particular had limited understanding about harm reduction and the feasibility and appropriateness of harm reduction services in the Lao context. Harm reduction should be a core element of a public health response to HIV where drug use and IDU exists. Recommendations include the necessity of increasing the awareness of harm reduction among law enforcement officers and providing appropriate evidence to support the needs of harm reduction policy and programs. HIV prevention and treatment strategies should be integrated within existing social and cultural frameworks, working with the task force for HIV/IDU and other government counterparts. PMID:22769736

  15. Defining and redefining harm reduction in the Lao context.

    PubMed

    Sychareun, Vanphanom; Hansana, Visanou; Phommachanh, Sysavanh; Somphet, Vathsana; Phommavongsa, Phouthong; Tenni, Brigitte; Moore, Timothy; Crofts, Nick

    2012-07-09

    The response to drug use in Laos has focused on reducing opium supply (supply reduction) and rates of drug use (demand reduction). However, recently there is increased interest among government counterparts to discuss and develop broader responses to injecting drug use (IDU) including the introduction of harm reduction programs. The concept of harm reduction has just been introduced to Lao PDR and as yet there is no agreement on a definition of the concept. We highlight here a range of issues that remain controversial in Lao PDR in the HIV, drug use and harm reduction discourse, the definition of 'harm reduction' and related terms; and the scope of harm reduction.This was a qualitative study, consisting of in-depth interviews with 27 law enforcement and 8 health officers who work in the fields of HIV and/or drug control about their understanding of HIV related to drug use, and concepts of harm reduction. Content analysis was performed to identify the coding, categories and themes.We found that law enforcement officers in particular had limited understanding about harm reduction and the feasibility and appropriateness of harm reduction services in the Lao context.Harm reduction should be a core element of a public health response to HIV where drug use and IDU exists. Recommendations include the necessity of increasing the awareness of harm reduction among law enforcement officers and providing appropriate evidence to support the needs of harm reduction policy and programs. HIV prevention and treatment strategies should be integrated within existing social and cultural frameworks, working with the task force for HIV/IDU and other government counterparts.

  16. Rodent-borne hantaviruses in Cambodia, Lao PDR, and Thailand.

    PubMed

    Blasdell, Kim; Cosson, Jean François; Chaval, Yannick; Herbreteau, Vincent; Douangboupha, Bounneuang; Jittapalapong, Sathaporn; Lundqvist, Ake; Hugot, Jean-Pierre; Morand, Serge; Buchy, Philippe

    2011-12-01

    In order to evaluate the circulation of hantaviruses present in southeast Asia, a large scale survey of small mammal species was carried out at seven main sites in the region (Cambodia, Lao People's Democratic Republic, and Thailand). Small scale opportunistic trapping was also performed at an eighth site (Cambodia). Using a standard IFA test, IgG antibodies reacting to Hantaan virus antigens were detected at six sites. Antibody prevalence at each site varied from 0 to 5.6% with antibodies detected in several rodent species (Bandicota indica, B. savilei, Maxomys surifer, Mus caroli, M. cookii, Rattus exulans, R. nitidius, R. norvegicus, and R. tanezumi). When site seroprevalence was compared with site species richness, seropositive animals were found more frequently at sites with lower species richness. In order to confirm which hantavirus species were present, a subset of samples was also subjected to RT-PCR. Hantaviral RNA was detected at a single site from each country. Sequencing confirmed the presence of two hantavirus species, Thailand and Seoul viruses, including one sample (from Lao PDR) representing a highly divergent strain of Seoul virus. This is the first molecular evidence of hantavirus in Lao PDR and the first reported L segment sequence data for Thailand virus.

  17. Immunological identification of the alternative oxidase of Neurospora crassa mitochondria.

    PubMed Central

    Lambowitz, A M; Sabourin, J R; Bertrand, H; Nickels, R; McIntosh, L

    1989-01-01

    Neurospora crassa mitochondria use a branched electron transport system in which one branch is a conventional cytochrome system and the other is an alternative cyanide-resistant, hydroxamic acid-sensitive oxidase that is induced when the cytochrome system is impaired. We used a monoclonal antibody to the alternative oxidase of the higher plant Sauromatum guttatum to identify a similar set of related polypeptides (Mr, 36,500 and 37,000) that was associated with the alternative oxidase activity of N. crassa mitochondria. These polypeptides were not present constitutively in the mitochondria of a wild-type N. crassa strain, but were produced in high amounts under conditions that induced alternative oxidase activity. Under the same conditions, mutants in the aod-1 gene, with one exception, produced apparently inactive alternative oxidase polypeptides, whereas mutants in the aod-2 gene failed to produce these polypeptides. The latter findings support the hypothesis that aod-1 is a structural gene for the alternative oxidase and that the aod-2 gene encodes a component that is required for induction of alternative oxidase activity. Finally, our results indicate that the alternative oxidase is highly conserved, even between plant and fungal species. Images PMID:2524649

  18. An investigation into the antigenic cross-reactivity of Ophiophagus hannah (king cobra) venom neurotoxin, phospholipase A2, hemorrhagin and L-amino acid oxidase using enzyme-linked immunosorbent assay.

    PubMed

    Tan, N H; Lim, K K; Jaafar, M I

    1993-07-01

    The antigenic cross-reactivity of four Ophiophagus hannah (king cobra) venom components, the neurotoxin (OH-NTX), phospholipase A2 (OH-PLA2), hemorrhagin (OH-HMG) and L-amino acid oxidase (OH-LAAO) were examined by indirect and double sandwich ELISAs. The indirect ELISAs for OH-NTX, OH-PLA2 and OH-HMG were very specific when assayed against the various heterologous snake venoms and O. hannah venom components, at 25 ng/ml antigen level. At higher antigen concentrations (100-400 ng/ml), there were moderate to strong indirect ELISA cross-reactions between anti-O. hannah neurotoxin and venoms from various species of cobra as well as two short neurotoxins. However, anti-O. hannah hemorrhagin did not cross-react with any of the venoms tested, even at these high antigen concentrations, indicating that O. hannah hemorrhagin is antigenically very different from other venom hemorrhagins. Examination of the indirect ELISA cross-reactions between anti-O. hannah PLA2 and several elapid PLA2 enzymes suggests that the elapid PLA2 antigenic class has more than two subgroups. The antibodies to O. hannah L-amino acid oxidase, however, yielded indirect ELISA cross-reactions with many venoms as well as with OH-NTX, OH-PLA2 and OH-HMG, indicating that OH-LAAO shares common epitopes even with unrelated proteins. The double sandwich ELISAs for the four anti-O. hannah venom components, on the other hand, generally exhibited a higher degree of selectivity than the indirect ELISA procedure.

  19. High resolution crystal structure of rat long chain hydroxy acid oxidase in complex with the inhibitor 4-carboxy-5-[(4-chlorophenyl)sulfanyl]-1, 2, 3-thiadiazole. Implications for inhibitor specificity and drug design

    SciTech Connect

    Chen, Zhi-wei; Vignaud, Caroline; Jaafar, Adil; Lévy, Bernard; Guéritte, Françoise; Guénard, Daniel; Lederer, Florence; Mathews, F. Scott

    2012-05-24

    Long chain hydroxy acid oxidase (LCHAO) is responsible for the formation of methylguanidine, a toxic compound with elevated serum levels in patients with chronic renal failure. Its isozyme glycolate oxidase (GOX), has a role in the formation of oxalate, which can lead to pathological deposits of calcium oxalate, in particular in the disease primary hyperoxaluria. Inhibitors of these two enzymes may have therapeutic value. These enzymes are the only human members of the family of FMN-dependent L-2-hydroxy acid-oxidizing enzymes, with yeast flavocytochrome b{sub 2} (Fcb2) among its well studied members. We screened a chemical library for inhibitors, using in parallel rat LCHAO, human GOX and the Fcb2 flavodehydrogenase domain (FDH). Among the hits was an inhibitor, CCPST, with an IC{sub 50} in the micromolar range for all three enzymes. We report here the crystal structure of a complex between this compound and LCHAO at 1.3 {angstrom} resolution. In comparison with a lower resolution structure of this enzyme, binding of the inhibitor induces a conformational change in part of the TIM barrel loop 4, as well as protonation of the active site histidine. The CCPST interactions are compared with those it forms with human GOX and those formed by two other inhibitors with human GOX and spinach GOX. These compounds differ from CCPST in having the sulfur replaced with a nitrogen in the five-membered ring as well as different hydrophobic substituents. The possible reason for the {approx}100-fold difference in affinity between these two series of inhibitors is discussed. The present results indicate that specificity is an issue in the quest for therapeutic inhibitors of either LCHAO or GOX, but they may give leads for this quest.

  20. Succinate oxidase in Neurospora.

    PubMed

    West, D J; Woodward, D O

    1973-02-01

    Two kinetically distinct states of succinate oxidase have been detected in the mitochondria of Neruospora crassa. One state has a K(m) for succinate of 4.1 x 10(-3)m, and the other has a K(m) for succinate of 3.5 x 10(-4)m. The high K(m) state was found in freshly extracted mitochondria from either 20- or 72-hr mycelium. However, the succinate oxidase activity in mitochondria from 20-hr mycelium rapidly deteriorated in vitro, leaving a stable residual activity with the lower K(m) for succinate. Adenosine triphosphate (ATP) plus Mg(2+) stabilized the high K(m) state in these preparations. The high K(m) state of succinate oxidase was further characterized by a two- to threefold increase in activity over the pH range 6.6 to 8.0 and by classical competitive inhibition by fumarate and malonate. By contrast, the low K(m) state of succinate oxidase showed a relatively flat response to pH over the range 6.6 to 8.0 and a nonclassical pattern of inhibition by fumarate and malonate, as shown by nonlinear plots of reciprocal velocity versus reciprocal substrate concentration in the presence of inhibitor or reciprocal velocity versus inhibitor concentration at fixed substrate concentrations. The relationship of mycelial age to the in vitro stability of succinate oxidase is considered with reference to probable changes in the relative pool sizes of extra- and intramitochondrial ATP in response to changes in the rate of glycolysis.

  1. Microdialysis with radiometric monitoring of L-[β-11C]DOPA to assess dopaminergic metabolism: effect of inhibitors of L-amino acid decarboxylase, monoamine oxidase, and catechol-O-methyltransferase on rat striatal dialysate.

    PubMed

    Okada, Maki; Nakao, Ryuji; Hosoi, Rie; Zhang, Ming-Rong; Fukumura, Toshimitsu; Suzuki, Kazutoshi; Inoue, Osamu

    2011-01-01

    The catecholamine, dopamine (DA), is synthesized from 3,4-dihydroxy-L-phenylalanine (L-DOPA) by aromatic L-amino acid decarboxylase (AADC). Dopamine metabolism is regulated by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). To measure dopaminergic metabolism, we used microdialysis with radiometric detection to monitor L-[β-(11)C]DOPA metabolites in the extracellular space of the rat striatum. We also evaluated the effects of AADC, MAO, and COMT inhibitors on metabolite profiles. The major early species measured after administration of L-[β-(11)C]DOPA were [(11)C]3,4-dihydroxyphenylacetic acid ([(11)C]DOPAC) and [(11)C]homovanillic acid ([(11)C]HVA) in a 1:1 ratio, which shifted toward [(11)C]HVA with time. An AADC inhibitor increased the uptake of L-[β-(11)C]DOPA and L-3-O-methyl-[(11)C]DOPA and delayed the accumulation of [(11)C]DOPAC and [(11)C]HVA. The MAO and COMT inhibitors increased the production of [(11)C]3-methoxytyramine and [(11)C]DOPAC, respectively. These results reflect the L-DOPA metabolic pathway, suggesting that this method may be useful for assessing dopaminergic metabolism.

  2. Identification of Genes Involved in Indole-3-Acetic Acid Biosynthesis by Gluconacetobacter diazotrophicus PAL5 Strain Using Transposon Mutagenesis

    PubMed Central

    Rodrigues, Elisete P.; Soares, Cleiton de Paula; Galvão, Patrícia G.; Imada, Eddie L.; Simões-Araújo, Jean L.; Rouws, Luc F. M.; de Oliveira, André L. M.; Vidal, Márcia S.; Baldani, José I.

    2016-01-01

    Gluconacetobacter diazotrophicus is a beneficial nitrogen-fixing endophyte found in association with sugarcane plants and other important crops. Beneficial effects of G. diazotrophicus on sugarcane growth and productivity have been attributed to biological nitrogen fixation process and production of phytohormones especially indole-3-acetic acid (IAA); however, information about the biosynthesis and function of IAA in G. diazotrophicus is still scarce. Therefore, the aim of this work was to identify genes and pathways involved in IAA biosynthesis in this bacterium. In our study, the screening of two independent Tn5 mutant libraries of PAL5T strain using the Salkowski colorimetric assay revealed two mutants (Gdiaa34 and Gdiaa01), which exhibited 95% less indolic compounds than the parental strain when grown in LGIP medium supplemented with L-tryptophan. HPLC chromatograms of the wild-type strain revealed the presence of IAA and of the biosynthetic intermediates indole-3-pyruvic acid (IPyA) and indole-3-lactate (ILA). In contrast, the HPLC profiles of both mutants showed no IAA but only a large peak of non-metabolized tryptophan and low levels of IPyA and ILA were detected. Molecular characterization revealed that Gdiaa01 and Gdiaa34 mutants had unique Tn5 insertions at different sites within the GDI2456 open read frame, which is predicted to encode a L-amino acid oxidase (LAAO). GDI2456 (lao gene) forms a cluster with GDI2455 and GDI2454 ORFs, which are predicted to encode a cytochrome C and an RidA protein, respectively. RT-qPCR showed that transcript levels of lao. cccA, and ridA genes were reduced in the Gdiaa01 as compared to PAL5T. In addition, rice plants inoculated with Gdiaa01 showed significantly smaller root development (length, surface area, number of forks and tips) than those plants inoculated with PAL5T. In conclusion, our study demonstrated that G. diazotrophicus PAL5T produces IAA via the IPyA pathway in cultures supplemented with tryptophan and

  3. Educational Development and Reform on the Soviet Periphery: Mongolian People's Republic and Lao People's Democratic Republic.

    ERIC Educational Resources Information Center

    Spaulding, Seth

    1990-01-01

    This document examines educational reforms that have occurred in Mongolia and Laos. Both nations have expanded educational opportunity drastically over the years. Both had extensive literacy campaigns following the establishment of socialism. Laos has undertaken development projects with the support of the USSR, Eastern European countries, and…

  4. Lao People's Democratic Republic--Skills Development for Disadvantaged Groups: Review, Issues and Prospects. Final Report

    ERIC Educational Resources Information Center

    Online Submission, 2005

    2005-01-01

    In order to achieve the EFA (Education For All) goal agreed by participating nations at the Dakar World Education Forum 2000, The Lao government has undertaken various studies for its "National Plan of Action for Education for All." Lao is an inland mountainous nation with 49 ethnic groups. Such diversity makes the provision of social…

  5. Ambivalent Urban, Immigrant Identities: The Incompleteness of Lao American Student Identities

    ERIC Educational Resources Information Center

    Ngo, Bic

    2009-01-01

    In this article, the author elucidates the identity work of Lao American urban, immigrant students, highlighting ambivalent identities that do not fit into notions of bicultural or binary identities. It examines the various discourses and practices that inform and shape the experiences and identities of urban, Lao American high school students. It…

  6. Contextual Factors Affecting Learning in Laos and the Implications for Information Literacy Education

    ERIC Educational Resources Information Center

    Dorner, Daniel G.; Gorman, G. E.

    2011-01-01

    Introduction: Laos is used as a case study of how factors such as culture and indigenous knowledge must be considered to plan for information literacy education that is culturally and contextually appropriate. Method: Data were obtained from observations during visits to four Lao schools and from interviews with fourteen teachers at these schools.…

  7. Hunting, Food Preparation, and Consumption of Rodents in Lao PDR.

    PubMed

    Suwannarong, Kanokwan; Chapman, Robert S; Lantican, Cecile; Michaelides, Tula; Zimicki, Susan

    2015-01-01

    A cross-sectional study was conducted in 29 villages of Khamkeuth District in Bolikhamxay Province in the Lao PDR during March to May 2013. The study aimed to determine the characteristics associated with rodent consumption and related behaviors among different ethnic groups, ages, and genders. Five-hundred-eighty-four (584) males and females from 18-50 years of age participated in this study. Half of them were Hmong (292, 50%) while 152 respondents were Lao-Tai (26%) or other ethnic groups (140, 24%). Most of the respondents (79.5%) had farming as their main occupation. Prevalences of the studied outcomes were high: 39.9 for hunting or capturing rodents in the previous year, 77.7% for preparing rodents as food, and 86.3% for rodent consumption. Multivariable logistic regression analysis showed that likelihood of these types of rodent contact was more consistently associated with behavioral factors (gathering things from the forest and elsewhere, cultivation-related activities, and taking measures to prevent rodent-borne disease) than with socio-demographic, environmental, or cultural factors. The strongest associations were observed for gathering things; these associations were consistently positive and statistically significant. Although this study did not directly assess rodent-borne zoonosis risk, we believe that study findings raise concern that such risk may be substantial in the study area and other similar areas. Further epidemiological studies on the association between rodent-borne disease infection and rodent hunting, preparation for food, and consumption are recommended. Moreover, further studies are needed on the association between these potential exposure factors (i.e., rodent hunting, preparation for food, and consumption) and rodent-borne infections, especially among ethnic groups like the Hmong in Lao PDR and those in neighboring countries with similar socio-demographic, environmental, behavioral and cultural contexts.

  8. High prevalence of mumps in Lao People's Democratic Republic.

    PubMed

    Hübschen, J M; Vilivong, K; Souvannaso, C; Black, A P; Lütteke, N; Samountry, B; Phongsavath, V; Khamphaphongphane, B; Denny, J; Sayyavong, C; Woo, G K S; Sengsaya, K; Sausy, A; Vongphrachanh, P; Jutavijittum, P; Phonekeo, D; Muller, C P

    2014-10-01

    In the Lao People's Democratic Republic (PDR), mumps is not a notifiable disease and mumps vaccine is currently not included in the routine childhood immunization programme. In order to assess the burden of disease, we investigated the seroprevalence of mumps-specific IgG antibodies across four provinces. In addition, we genetically characterized mumps viruses from the past 3 years from several outbreaks and single cases. Blood and/or throat swabs from suspected cases were investigated for specific IgM antibodies or viral RNA. Mumps cases occurred between March and November in 2011-2013 and 5- to 15-year-olds were most affected. Four sequences from an outbreak in the north of Lao PDR in 2011 were identical and belonged to genotype G. Eight sequences from two outbreaks and two individual cases from 2012 and 2013 belonged to genotype J. In addition, sera collected from 2379 healthy infants and school pupils aged between 9 months and 19 years and from pregnant women aged between 16 and 46 years were investigated for mumps-specific IgG. Overall, 58.2% were positive, 39.5% were negative and the remaining 2.3% were equivocal. The seropositivity increased with age, with the lowest percentage found in <1-year-old infants (9.1%) and the highest in the cohort of pregnant women (69.2%). More female subjects than male subjects were seropositive (60.4 vs. 54.9%). There were some differences between the locations. Mumps should be a notifiable disease in Lao PDR in order to get more accurate case numbers and cost estimates for public health-care, and vaccination of children and high-risk groups should be considered.

  9. Hunting, Food Preparation, and Consumption of Rodents in Lao PDR

    PubMed Central

    Suwannarong, Kanokwan; Chapman, Robert S.; Lantican, Cecile; Michaelides, Tula; Zimicki, Susan

    2015-01-01

    A cross-sectional study was conducted in 29 villages of Khamkeuth District in Bolikhamxay Province in the Lao PDR during March to May 2013. The study aimed to determine the characteristics associated with rodent consumption and related behaviors among different ethnic groups, ages, and genders. Five-hundred-eighty-four (584) males and females from 18-50 years of age participated in this study. Half of them were Hmong (292, 50%) while 152 respondents were Lao-Tai (26%) or other ethnic groups (140, 24%). Most of the respondents (79.5%) had farming as their main occupation. Prevalences of the studied outcomes were high: 39.9 for hunting or capturing rodents in the previous year, 77.7% for preparing rodents as food, and 86.3% for rodent consumption. Multivariable logistic regression analysis showed that likelihood of these types of rodent contact was more consistently associated with behavioral factors (gathering things from the forest and elsewhere, cultivation-related activities, and taking measures to prevent rodent-borne disease) than with socio-demographic, environmental, or cultural factors. The strongest associations were observed for gathering things; these associations were consistently positive and statistically significant. Although this study did not directly assess rodent-borne zoonosis risk, we believe that study findings raise concern that such risk may be substantial in the study area and other similar areas. Further epidemiological studies on the association between rodent-borne disease infection and rodent hunting, preparation for food, and consumption are recommended. Moreover, further studies are needed on the association between these potential exposure factors (i.e., rodent hunting, preparation for food, and consumption) and rodent-borne infections, especially among ethnic groups like the Hmong in Lao PDR and those in neighboring countries with similar socio-demographic, environmental, behavioral and cultural contexts. PMID:26196134

  10. Helminth infection in southern Laos: high prevalence and low awareness

    PubMed Central

    2013-01-01

    Background Helminthiasis is a public health concern in Lao People’s Democratic Republic (Lao PDR, Laos). This study aimed to understand helminth infection and associated risk factors in relation to existing local knowledge, attitudes and practices regarding worm infections in endemic communities. Methods A cross-sectional survey was conducted in 10 randomly selected villages in Saravane district, Southern Laos. Two stool samples obtained from 574 members (aged ≥2 years) of selected households were examined using the Kato Katz method. Household heads (n = 130) were interviewed. Eight focus group discussions (FGDs) and direct observations were performed. Uni- and multivariate logistic regression analyses were conducted to predict infection. Content analysis was conducted for qualitative data. Results The prevalence of Opisthorchis viverrini, hookworm, Trichuris trichiura, Ascaris lumbricoides and Taenia sp. was 88.7%, 86.6%, 32.9%, 9.8% and 11.5%, respectively. Most individuals were co-infected with O. viverrini and hookworm. More men had multiple helminth infections than did women. Only one-third of household heads had heard about liver fluke before, of which 59.2% associated it with eating raw fish dish. Among the soil-transmitted helminths, roundworm was the most well known (70.8%) but was attributed to raw food consumption (91.3%). Eating raw fish was a common practice (75.4%); few households possessed a latrine (16.1%); less than half of the study participants mentioned health benefits from latrine use and personal hygiene. Focus group discussion participants had a low level of awareness of worm infections; more men liked eating raw fish than did women; some disliked using latrines because they were not used to it and because of their bad smell. Poor personal and village hygiene practices were observed. Conclusions This study highlights a high helminth infection rate and poor community awareness of worm infections and associated risk factors. Only a

  11. A new small-sized Theloderma (Anura: Rhacophoridae) from Laos.

    PubMed

    Sivongxay, Niane; Davankham, Monekham; Phimmachak, Somphouthone; Phoumixay, Keochay; Stuart, Bryan L

    2016-08-05

    A new species of the rhacophorid frog genus Theloderma is described from the forested shoreline of the Nam Lik Reservoir, Vientiane Province, Laos. The new species differs from its congeners by having the combination of males with SVL 17.0-20.6; pearly asperities on dorsum; no vomerine teeth; disc diameter of finger III ca. 40% of tympanum diameter; uniformly gray venter; light brown dorsum with darker brown and black markings; and a uniformly bronze iris with small black reticulations. Molecular phylogenetic analysis of mitochondrial DNA sequence data infers that the new species is most closely related to T. lateriticum from northern Vietnam. Evidence for the monophyly of Theloderma is reviewed.

  12. A biochemical approach to study the role of the terminal oxidases in aerobic respiration in Shewanella oneidensis MR-1.

    PubMed

    Le Laz, Sébastien; Kpebe, Arlette; Bauzan, Marielle; Lignon, Sabrina; Rousset, Marc; Brugna, Myriam

    2014-01-01

    The genome of the facultative anaerobic γ-proteobacterium Shewanella oneidensis MR-1 encodes for three terminal oxidases: a bd-type quinol oxidase and two heme-copper oxidases, a A-type cytochrome c oxidase and a cbb 3-type oxidase. In this study, we used a biochemical approach and directly measured oxidase activities coupled to mass-spectrometry analysis to investigate the physiological role of the three terminal oxidases under aerobic and microaerobic conditions. Our data revealed that the cbb 3-type oxidase is the major terminal oxidase under aerobic conditions while both cbb 3-type and bd-type oxidases are involved in respiration at low-O2 tensions. On the contrary, the low O2-affinity A-type cytochrome c oxidase was not detected in our experimental conditions even under aerobic conditions and would therefore not be required for aerobic respiration in S. oneidensis MR-1. In addition, the deduced amino acid sequence suggests that the A-type cytochrome c oxidase is a ccaa 3-type oxidase since an uncommon extra-C terminal domain contains two c-type heme binding motifs. The particularity of the aerobic respiratory pathway and the physiological implication of the presence of a ccaa 3-type oxidase in S. oneidensis MR-1 are discussed.

  13. Characterization of two amine oxidases from Aspergillus carbonarius AIU 205.

    PubMed

    Sugawara, Asami; Matsui, Daisuke; Yamada, Miwa; Asano, Yasuhisa; Isobe, Kimiyasu

    2015-06-01

    We have reported that Aspergillus carbonarius AIU 205, which was isolated by our group, produced three enzymes exhibiting oxidase activity for 4-aminobutanamide (4-ABAD) (J. Biosci. Bioeng., 117, 263-268, 2014). Among three enzymes, characteristics of enzyme I have been revealed, but those of the other two enzymes have not. In this study, we purified enzymes II and III, and compared their characteristics with those of enzyme I. Enzymes II and III also oxidized aliphatic monoamines, aromatic amines, and aliphatic aminoalcohols. In addition, the oxidase activity of both enzymes was strongly inhibited by carbonyl reagents and specific inhibitors for copper-containing amine oxidases. Thus, enzymes II and III were also classified into the copper-containing amine oxidase group (EC 1.4.3.6) along with enzyme I. However, these three enzymes differed from each other in their enzymatic, kinetic, and physicochemical properties. The N-terminal amino acid sequences also differed from each other; that of enzyme I was modified, that of enzyme II was similar to those of peroxisomal copper-containing amine oxidases, and that of enzyme III was similar to those of copper-containing amine oxidases from the genus Aspergillus. Therefore, we concluded that A. carbonarius AIU 205 produced three different types of amine oxidase in the mycelia.

  14. Specific Inhibition of Acyl-CoA Oxidase-1 by an Acetylenic Acid Improves Hepatic Lipid and Reactive Oxygen Species (ROS) Metabolism in Rats Fed a High Fat Diet.

    PubMed

    Zeng, Jia; Deng, Senwen; Wang, Yiping; Li, Ping; Tang, Lian; Pang, Yefeng

    2017-03-03

    A chronic high fat diet results in hepatic mitochondrial dysfunction and induction of peroxisomal fatty acid oxidation (FAO); whether specific inhibition of peroxisomal FAO benefits mitochondrial FAO and reactive oxygen species (ROS) metabolism remains unclear. In this study a specific inhibitor for the rate-limiting enzyme involved in peroxisomal FAO, acyl-CoA oxidase-1 (ACOX1) was developed and used for the investigation of peroxisomal FAO inhibition upon mitochondrial FAO and ROS metabolism. Specific inhibition of ACOX1 by 10,12-tricosadiynoic acid increased hepatic mitochondrial FAO via activation of the SIRT1-AMPK (adenosine 5'-monophosphate-activated protein kinase) pathway and proliferator activator receptor α and reduced hydrogen peroxide accumulation in high fat diet-fed rats, which significantly decreased hepatic lipid and ROS contents, reduced body weight gain, and decreased serum triglyceride and insulin levels. Inhibition of ACOX1 is a novel and effective approach for the treatment of high fat diet- or obesity-induced metabolic diseases by improving mitochondrial lipid and ROS metabolism.

  15. Oriented and selective enzyme immobilization on functionalized silica carrier using the cationic binding module Z basic2: design of a heterogeneous D-amino acid oxidase catalyst on porous glass.

    PubMed

    Bolivar, Juan M; Nidetzky, Bernd

    2012-06-01

    D-amino acid oxidase from Trigonopsis variabilis (TvDAO) is applied in industry for the synthesis of pharmaceutical intermediates. Because free TvDAO is extremely sensitive to exposure to gas-liquid interfaces, biocatalytic processing is usually performed with enzyme immobilizates that offer enhanced stability under bubble aeration. We herein present an "Immobilization by Design" approach that exploits engineered charge complementarity between enzyme and carrier to optimize key features of the immobilization of TvDAO. A fusion protein between TvDAO and the positively charged module Z(basic2) was generated, and a corresponding oppositely charged carrier was obtained by derivatization of mesoporous glass with 3-(trihydroxysilyl)-1-propane-sulfonic acid. Using 250 mM NaCl for charge screening at pH 7.0, the Z(basic2) fusion of TvDAO was immobilized directly from E. coli cell extract with almost absolute selectivity and full retention of catalytic effectiveness of the isolated enzyme in solution. Attachment of the homodimeric enzyme to the carrier was quasi-permanent in low-salt buffer but fully reversible upon elution with 5 M NaCl. Immobilized TvDAO was not sensitive to bubble aeration and received substantial (≥ tenfold) stabilization of the activity at 45°C as compared to free enzyme, suggesting immobilization via multisubunit oriented interaction of enzyme with the insoluble carrier. The Z(basic2) enzyme immobilizate was demonstrated to serve as re-usable heterogeneous catalyst for D-amino acid oxidation. Z(basic2) -mediated binding on a sulfonic acid group-containing glass carrier constitutes a generally useful strategy of enzyme immobilization that supports transition from case-specific empirical development to rational design.

  16. Selective monoamine oxidase B inhibition by an Aphanizomenon flos-aquae extract and by its constitutive active principles phycocyanin and mycosporine-like amino acids.

    PubMed

    Scoglio, Stefano; Benedetti, Yanina; Benvenuti, Francesca; Battistelli, Serafina; Canestrari, Franco; Benedetti, Serena

    2014-06-15

    Aphanizomenon flos-aquae (AFA) is a fresh water unicellular blue-green alga that has been traditionally used for over 25 years for its health-enhancing properties. Recent studies have shown the ability of a proprietary AFA extract (Klamin(®)) to improve mood, counteract anxiety, and enhance attention and learning. Aim of this study was to test the monoamine oxidase (MAO) inhibition activity of the same AFA extract and of its constituents phycocyanin (AFA-PC) and mycosporine-like aminoacids (AFA-MAAs). All compounds showed a dose-dependent selective inhibition of MAO-B activity as compared to MAO-A. The IC50 values of the AFA extract (concentration 10 mg/ml), AFA-PC and AFA-MAAs were 6.4 μl/ml, 1.33 μM and 1.98 μM, respectively, evidencing a mixed-type of inhibition for the AFA extract (Ki 0.99 μl/ml), a non-competitive inhibition for AFA-PC (Ki 1.06 μM) and a competitive inhibition for AFA-MAAs (Ki 0.585 μM). These results are important to explain the neuromodulating properties of the AFA extract Klamin(®), which is rich in phenylethylamine, a general neuromodulator, that would nevertheless rapidly destroyed by MAO-B enzymes without the inhibitory activity of the synergic active principles AFA-PC and AFA-MAAs. The present investigation thus proposes the extract as potentially relevant in clinical areas such as mood disorders and neurodegenerative diseases.

  17. HypC, the anthrone oxidase involved in aflatoxin biosynthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Based on gene disruption and enzyme activity, hypC, an open reading frame in the pksA (aflC)/nor-1 (aflD) intergenic region in the aflatoxin biosynthesis cluster, encodes a 17 kDa oxidase that catalyzes the conversion of norsolorinic acid anthrone to norsolorinic acid....

  18. A new species of Hemiphyllodactylus (Reptilia: Gekkonidae) from northern Laos.

    PubMed

    Nguyen, Truong Quang; Botov, Andreas; Le, Minh Duc; Nophaseud, Liphone; Zug, George; Bonkowski, Michael; Ziegler, Thomas

    2014-07-02

    A new species of the genus Hemiphyllodactylus is described from Luang Prabang Province, northern Laos. Hemiphyllodactylus kiziriani sp. nov. is distinguished from the remaining congeners by morphology, coloration, and a significant genetic divergence of greater than 20% (ND2 gene). The new species from Laos is characterized by the following features: SVL of adult males 35.1-40.1 mm, of adult females 36.3-40.8 mm; dorsal scale rows 18-27; ventral scale rows 11-15; chin scales bordering mental and first infralabial distinctly enlarged; digital lamellae formulae 3-4-4-4 (forefoot) and 4-4/5-4/5-4 (hindfoot); femoral pores 0-4, total precloacal pores 10-13 in males, 8-10 pitted precloacal scales in females; cloacal spurs present in both sexes; dorsal trunk pattern dark brown with two rows of irregular transverse bands; dark lateral head stripe distinct; upper zone of flank with a dark brown stripe; caecum and gonadal ducts unpigmented.

  19. Azide inhibition of urate oxidase.

    PubMed

    Gabison, Laure; Colloc'h, Nathalie; Prangé, Thierry

    2014-07-01

    The inhibition of urate oxidase (UOX) by azide was investigated by X-ray diffraction techniques and compared with cyanide inhibition. Two well characterized sites for reagents are present in the enzyme: the dioxygen site and the substrate-binding site. To examine the selectivity of these sites towards azide inhibition, several crystallization conditions were developed. UOX was co-crystallized with azide (N3) in the presence or absence of either uric acid (UA, the natural substrate) or 8-azaxanthine (8AZA, a competitive inhibitor). In a second set of experiments, previously grown orthorhombic crystals of the UOX-UA or UOX-8AZA complexes were soaked in sodium azide solutions. In a third set of experiments, orthorhombic crystals of UOX with the exchangeable ligand 8-nitroxanthine (8NXN) were soaked in a solution containing uric acid and azide simultaneously (competitive soaking). In all assays, the soaking periods were either short (a few hours) or long (one or two months). These different experimental conditions showed that one or other of the sites, or the two sites together, could be inhibited. This also demonstrated that azide not only competes with dioxygen as cyanide does but also competes with the substrate for its enzymatic site. A model in agreement with experimental data would be an azide in equilibrium between two sites, kinetically in favour of the dioxygen site and thermodynamically in favour of the substrate-binding site.

  20. Azide inhibition of urate oxidase

    PubMed Central

    Gabison, Laure; Colloc’h, Nathalie; Prangé, Thierry

    2014-01-01

    The inhibition of urate oxidase (UOX) by azide was investigated by X-ray diffraction techniques and compared with cyanide inhibition. Two well characterized sites for reagents are present in the enzyme: the dioxygen site and the substrate-binding site. To examine the selectivity of these sites towards azide inhibition, several crystallization conditions were developed. UOX was co-crystallized with azide (N3) in the presence or absence of either uric acid (UA, the natural substrate) or 8-azaxanthine (8AZA, a competitive inhibitor). In a second set of experiments, previously grown orthorhombic crystals of the UOX–UA or UOX–8AZA complexes were soaked in sodium azide solutions. In a third set of experiments, orthorhombic crystals of UOX with the exchangeable ligand 8-nitroxanthine (8NXN) were soaked in a solution containing uric acid and azide simultaneously (competitive soaking). In all assays, the soaking periods were either short (a few hours) or long (one or two months). These different experimental conditions showed that one or other of the sites, or the two sites together, could be inhibited. This also demonstrated that azide not only competes with dioxygen as cyanide does but also competes with the substrate for its enzymatic site. A model in agreement with experimental data would be an azide in equilibrium between two sites, kinetically in favour of the dioxygen site and thermodynamically in favour of the substrate-binding site. PMID:25005084

  1. Bartonella and Rickettsia in arthropods from the Lao PDR and from Borneo, Malaysia.

    PubMed

    Kernif, Tahar; Socolovschi, Cristina; Wells, Konstans; Lakim, Maklarin B; Inthalad, Saythong; Slesak, Günther; Boudebouch, Najma; Beaucournu, Jean-Claude; Newton, Paul N; Raoult, Didier; Parola, Philippe

    2012-01-01

    Rickettsioses and bartonelloses are arthropod-borne diseases of mammals with widespread geographical distributions. Yet their occurrence in specific regions, their association with different vectors and hosts and the infection rate of arthropod-vectors with these agents remain poorly studied in South-east Asia. We conducted entomological field surveys in the Lao PDR (Laos) and Borneo, Malaysia by surveying fleas, ticks, and lice from domestic dogs and collected additional samples from domestic cows and pigs in Laos. Rickettsia felis was detected by real-time PCR with similar overall flea infection rate in Laos (76.6%, 69/90) and Borneo (74.4%, 268/360). Both of the encountered flea vectors Ctenocephalides orientis and Ctenocephalides felis felis were infected with R. felis. The degrees of similarity of partial gltA and ompA genes with recognized species indicate the rickettsia detected in two Boophilus spp. ticks collected from a cow in Laos may be a new species. Isolation and further characterization will be necessary to specify it as a new species. Bartonella clarridgeiae was detected in 3/90 (3.3%) and 2/360 (0.6%) of examined fleas from Laos and Borneo, respectively. Two fleas collected in Laos and one flea collected in Borneo were co-infected with both R. felis and B. clarridgeiae. Further investigations are needed in order to isolate these agents and to determine their epidemiology and aetiological role in unknown fever in patients from these areas.

  2. Source of Australasian Tektites: Investigating Possible Impact Sites in Laos

    NASA Astrophysics Data System (ADS)

    Schnetzler, C. C.; McHone, J. F.

    1995-09-01

    Approximately 770,000 years ago an asteroid or comet crashed with the Earth somewhere in southeast Asia, in what was arguably the largest terrestrial impact in the past several 10's of millions of years. Evidence for this impact is not a crater but ejecta from a crater - tektites, microtektites and impact debris - which are found over more than one-tenth of the Earth's surface. Despite its relative youth and the large size of the ejecta field, the structure produced by this impact has not yet been discovered. In the past few years searches have focused on eastern Indochina, specifically in northeast Thailand [1], Cambodia [2] and Laos [3]. In February, 1995 we spent ten days in southern Laos looking for the source crater. The trip was an outgrowth of an investigation using satellite imagery and a digital topographic database, which suggested the impact site might be one of several structures in southern Laos. The primary purpose of the trip was to investigate these structures; a secondary objective was to document tektite localities and to collect samples of known provenance. One crater-like structure identified from digital topographic and multispectral images seemed to be especially interesting due to its quasi-circular shape and relatively youthful appearance. Three additional suspicious structures were identified near this primary target, but these appeared much more subdued and highly eroded. All of these features lie in southern Laos within the broad region of Mesozoic marine sedimentary rocks, primarily sandstones interbedded with shales and limestones, which covers much of central Indochina. The top-priority structure, centered at 16.35 degrees N/106.15 degrees E, is a ring of steep-sided hills 35 to 40 km in diameter, rising 70 to several hundred meters above the surrounding flat plain. It also has a central elevated area rising about 100 meters above the floor, suggesting an eroded central uplift. Despite difficult field conditions we successfully

  3. Use of a quantitative oxidase test for characterizing oxidative metabolism in bacteria.

    PubMed Central

    Jurtshuk, P; McQuitty, D N

    1976-01-01

    It was possible to quantitate the terminal oxidase(s) reaction using bacterial resting-cell suspensions and demonstrate the usefulness of this reaction for taxonomic purposes. Resting-cell suspensions of physiologically diverse bacteria were examined for their capabilities of oxidizing N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) using a manometric assay. For organisms having this capability, it was possible to calculate the conventional TMPD oxidase Q(O2) value (microliters of O2 consumed per hour per milligram [dry weight]). All cultures were grown heterotrophically at 30 C, under identical nutritional conditions, and were harvested at the late-logarithmic growth phase. The TMPD oxidase Q(O2) values showed perfect correlation with the Kovacs oxidase test and, in addition, it was possible to define quantitatively that point which separated oxidase-positive from oxidase-negative bacteria. Oxidase-negative bacteria exhibited a TMPD oxidase Q(O2) value (after correcting for the endogenous by substraction) of less than or equal 33 and had an uncorrected TMPD/endogenous ratio of less than or equal 5. The TMPD oxidase Q(O2) values were also correlated with the data obtained for the Hugh-Leifson Oxferm test. In general, bacteria that exhibited a respiratory mechanism had high TMPD oxidase values, whereas fermentative organsims had low TMPD oxidase activity. All exceptions to this are noted. This quantitative study also demonstrated that organisms that (i) lack a type c cytochrome, or (ii) lack a cytochrome-containing electron transport system, like the lactic acid bacteria, exhibited low or negligible TMPD oxidase Q(O2) values. From the 79 bacterial species (36 genera) examined, it appears that this quantitative oxidase test has taxonomic value that can differentiate the oxidative relationships between bacteria at the subspecies, species, and genera levels. PMID:1275489

  4. Beriberi (Thiamine Deficiency) and High Infant Mortality in Northern Laos

    PubMed Central

    Barennes, Hubert; Sengkhamyong, Khouanheuan; René, Jean Pascal; Phimmasane, Maniphet

    2015-01-01

    Background Infantile beriberi (thiamine deficiency) occurs mainly in infants breastfed by mothers with inadequate intake of thiamine, typically among vulnerable populations. We describe possible and probable cases of infantile thiamine deficiency in northern Laos. Methodology/Principal Findings Three surveys were conducted in Luang Namtha Province. First, we performed a retrospective survey of all infants with a diagnosis of thiamine deficiency admitted to the 5 hospitals in the province (2007–2009). Second, we prospectively recorded all infants with cardiac failure at Luang Namtha Hospital. Third, we further investigated all mothers with infants (1–6 months) living in 22 villages of the thiamine deficiency patients’ origin. We performed a cross-sectional survey of all mothers and infants using a pre-tested questionnaire, physical examination and squat test. Infant mortality was estimated by verbal autopsy. From March to June 2010, four suspected infants with thiamine deficiency were admitted to Luang Namtha Provincial hospital. All recovered after parenteral thiamine injection. Between 2007 and 2009, 54 infants with possible/probable thiamine deficiency were diagnosed with acute severe cardiac failure, 49 (90.2%) were cured after parenteral thiamine; three died (5.6%). In the 22 villages, of 468 live born infants, 50 (10.6%, 95% CI: 8.0–13.8) died during the first year. A peak of mortality (36 deaths) was reported between 1 and 3 months. Verbal autopsy suggested that 17 deaths (3.6%) were due to suspected infantile thiamine deficiency. Of 127 mothers, 60 (47.2%) reported edema and paresthesia as well as a positive squat test during pregnancy; 125 (98.4%) respected post-partum food avoidance and all ate polished rice. Of 127 infants, 2 (1.6%) had probable thiamine deficiency, and 8 (6.8%) possible thiamine deficiency. Conclusion Thiamine deficiency may be a major cause of infant mortality among ethnic groups in northern Laos. Mothers’ and children

  5. An amperometric biosensor based on ascorbate oxidase immobilized in poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotubes composite films for the determination of L-ascorbic acid.

    PubMed

    Liu, Ming; Wen, Yangping; Xu, Jingkun; He, Haohua; Li, Dong; Yue, Ruirui; Liu, Guodong

    2011-01-01

    An amperometric L-ascorbic acid (AA) biosensor fabricated by immobilizing ascorbate oxidase (AO) in poly(3,4-ethylenedioxythiophene) (PEDOT) and multi-walled carbon nanotubes (MWCNTs) composite films was reported for the first time. The entrapment of AO in PEDOT/MWCNTs composite films was performed during an electrochemical polymerization process. The influence of various experimental conditions was examined for determining the optimum analytical performance. The response of the biosensor towards AA under the optimized conditions is linear from 0.05 to 20 mM with a detection limit of 15 µM (S/N = 3). The biosensor shows a response time of 20 s and a sensitivity of 23.95 mA M(-1) cm(-2). The apparent Michaelis-Menten constant (K(m)) and apparent activation energy (E(a)) are 19.5 mM and 21 kJ mol(-1), respectively. Moreover, the biosensor exhibits good anti-interferent ability, good reproducibility and remarkable storage stability.

  6. Synthesis, crystal structures, molecular docking, in vitro monoamine oxidase-B inhibitory activity of transition metal complexes with 2-{4-[bis (4-fluorophenyl)methyl]piperazin-1-yl} acetic acid

    NASA Astrophysics Data System (ADS)

    Yang, Dan-dan; Wang, Riu; Zhu, Jin-long; Cao, Qi-yue; Qin, Jie; Zhu, Hai-liang; Qian, Shao-song

    2017-01-01

    Three novel complexes, [Cu(L)2(H2O)](1), [Zn(L)2(H2O)2]·CH3OH·1.5H2O(2), and [Ni(L)2(H2O)1.8]·CH3OH·1.2H2O (3) (HL = 2-{4-[bis(4-fluorophenyl)methyl]pipera-zin-1-yl} acetic acid), were synthesized and structurally determined by single-crystal X-ray diffraction. Molecular docking study preliminarily revealed that complex 1 had potential Monoamine oxidase B inhibitory activity. All acquired compounds were tested against rat brain MAO-B in vitro. In accordance with the result of calculation, it showed complex 1 (IC50 = 1.85 ± 0.31 μM) have good inhibitory activity against MAO-B at the same micromolar concentrations with positive control Iproniazid Phosphate (IP, IC50 = 7.59 ± 1.17 μM). These results indicated that complex 1 was a potent MAO-B inhibitor.

  7. Bezafibrate induces acyl-CoA oxidase mRNA levels and fatty acid peroxisomal beta-oxidation in rat white adipose tissue.

    PubMed

    Vázquez, M; Roglans, N; Cabrero, A; Rodríguez, C; Adzet, T; Alegret, M; Sánchez, R M; Laguna, J C

    2001-01-01

    Rats treated with bezafibrate, a PPAR activator, gain less body weight and increase daily food intake. Previously, we have related these changes to a shift of thermogenesis from brown adipose tissue to white adipose tissue attributable to bezafibrate, which induces uncoupling proteins (UCP), UCP-1 and UCP-3, in rat white adipocytes. Nevertheless, UCP induction was weak, implying additional mechanisms in the change of energy homeostasis produced by bezafibrate. Here we show that bezafibrate, in addition to inducing UCPs, modifies energy homeostasis by directly inducing aco gene expression and peroxisomal fatty acid beta-oxidation in white adipose tissue. Further, bezafibrate significantly reduced plasma triglyceride and leptin concentrations, without modifying the levels of PPARgamma or ob gene in white adipose tissue. These results indicate that bezafibrate reduces the amount of fatty acids available for triglyceride synthesis in white adipose tissue.

  8. Gekko aaronbaueri, a new gecko (Squamata: Gekkonidae) from central Laos.

    PubMed

    Tri, Ngo Van; Thai, Pham Hong; Phimvohan, Anorath; David, Patrick; Teynié, Alexandre

    2015-01-27

    A new species of the genus Gekko Laurenti is described from central Laos. The species is distinguished from its congeners by its moderate size, i.e. maximum SVL 80.0 mm, dorsal pattern of five to six dirty white vertebral spots alternating with yellowish-edged, W-shaped blotches between nape and sacrum and six to seven pairs of dirty white spots interspersed with yellowish-edged dark blotches on the flanks between limb insertions, 0-1 internasal, 39-43 ventral scale rows between the weakly developed ventrolateral folds, 3-4 precloacal pores in males, sometimes separated by one poreless scale, 98-104 smooth dorsal scale rows around the body, 16 broad lamellae beneath digit I of pes, 15-16 broad lamellae beneath digit IV of pes, and enlarged subcaudal scales. 

  9. Building capacity for protected area management in Lao PDR.

    PubMed

    Rao, Madhu; Johnson, Arlyne; Spence, Kelly; Sypasong, Ahnsany; Bynum, Nora; Sterling, Eleanor; Phimminith, Thavy; Praxaysombath, Bounthob

    2014-04-01

    Declining biodiversity in protected areas in Laos is attributed to unsustainable exploitation of natural resources. At a basic level, an important need is to develop capacity in academic and professional training institutions to provide relevant training to conservation professionals. The paper (a) describes the capacity building approach undertaken to achieve this goal, (b) evaluates the effectiveness of the approach in building capacity for implementing conservation and (c) reviews implementation outcomes. Strong linkages between organizations implementing field conservation, professional training institutions, and relevant Government agencies are central to enhancing effectiveness of capacity building initiatives aimed at improving the practice of conservation. Protected area management technical capacity needs will need to directly influence curriculum design to insure both relevance and effectiveness of training in improving protected area management. Sustainability of capacity building initiatives is largely dependent on the level of interest and commitment by host-country institutions within a supportive Government policy framework in addition to engagement of organizations implementing conservation.

  10. Building Capacity for Protected Area Management in Lao PDR

    NASA Astrophysics Data System (ADS)

    Rao, Madhu; Johnson, Arlyne; Spence, Kelly; Sypasong, Ahnsany; Bynum, Nora; Sterling, Eleanor; Phimminith, Thavy; Praxaysombath, Bounthob

    2014-04-01

    Declining biodiversity in protected areas in Laos is attributed to unsustainable exploitation of natural resources. At a basic level, an important need is to develop capacity in academic and professional training institutions to provide relevant training to conservation professionals. The paper (a) describes the capacity building approach undertaken to achieve this goal, (b) evaluates the effectiveness of the approach in building capacity for implementing conservation and (c) reviews implementation outcomes. Strong linkages between organizations implementing field conservation, professional training institutions, and relevant Government agencies are central to enhancing effectiveness of capacity building initiatives aimed at improving the practice of conservation. Protected area management technical capacity needs will need to directly influence curriculum design to insure both relevance and effectiveness of training in improving protected area management. Sustainability of capacity building initiatives is largely dependent on the level of interest and commitment by host-country institutions within a supportive Government policy framework in addition to engagement of organizations implementing conservation.

  11. Arabidopsis alternative oxidase sustains Escherichia coli respiration.

    PubMed Central

    Kumar, A M; Söll, D

    1992-01-01

    Glutamyl-tRNA reductase, encoded by the hemA gene, is the first enzyme in porphyrin biosynthesis in many organisms. Hemes, important porphyrin derivatives, are essential components of redox enzymes, such as cytochromes. Thus a hemA Escherichia coli strain (SASX41B) is deficient in cytochrome-mediated aerobic respiration. Upon complementation of this strain with an Arabidopsis thaliana cDNA library, we isolated a clone which permitted the SASX41B strain to grow aerobically. The clone encodes the gene for Arabidopsis alternative oxidase, whose deduced amino acid sequence was found to have 71% identity with that of the enzyme from the voodoo lily, Sauromatum guttatum. The Arabidopsis protein is expressed as a 31-kDa protein in E. coli and confers on this organism cyanide-resistant growth, which in turn is sensitive to salicylhydroxamate. This implies that a single polypeptide is sufficient for alternative oxidase activity. Based on these observations we propose that a cyanide-insensitive respiratory pathway operates in the transformed E. coli hemA strain. Introduction of this pathway now opens the way to genetic/molecular biological investigations of alternative oxidase and its cofactor. Images PMID:1438286

  12. Apoptosis induction in human breast cancer (MCF-7) cells by a novel venom L-amino acid oxidase (Rusvinoxidase) is independent of its enzymatic activity and is accompanied by caspase-7 activation and reactive oxygen species production.

    PubMed

    Mukherjee, Ashis K; Saviola, Anthony J; Burns, Patrick D; Mackessy, Stephen P

    2015-10-01

    We report the elucidation of a mechanism of apoptosis induction in breast cancer (MCF-7) cells by an L-amino acid oxidase (LAAO), Rusvinoxidase, purified from the venom of Daboia russelii russelii. Peptide mass fingerprinting analysis of Rusvinoxidase, an acidic monomeric glycoprotein with a mass of ~57 kDa, confirmed its identity as snake venom LAAO. The enzymatic activity of Rusvinoxidase was completely abolished after two cycles of freezing and thawing; however, its cytotoxicity toward MCF-7 cells remained unaffected. Dose- and time-dependent induction of apoptosis by Rusvinoxidase on MCF-7 cells was evident from changes in cell morphology, cell membrane integrity, shrinkage of cells and apoptotic body formation accompanied by DNA fragmentation. Rusvinoxidase induced apoptosis in MCF-7 cells by both the extrinsic (death-receptor) and intrinsic (mitochondrial) signaling pathways. The former pathway of apoptosis operated through activation of caspase-8 that subsequently activated caspase-7 but not caspase-3. Rusvinoxidase-induced intrinsic pathway of apoptosis was accompanied by a time-dependent depolarization of the mitochondrial membrane through the generation of reactive oxygen species, followed by a decrease in cellular glutathione content and catalase activity, and down-regulation of expression of anti-apoptotic proteins Bcl-XL and heat-shock proteins (HSP-90 and HSP-70). Rusvinoxidase treatment resulted in increase of the pro-apoptotic protein Bax, subsequently leading to the release of cytochrome c from mitochondria to the cytosol and activating caspase-9, which in turn stimulated effector caspase-7. Rusvinoxidase at a dose of 4 mg/kg was non-toxic in mice, indicating that it may be useful as a model for the development of peptide-based anticancer drugs.

  13. Project CHECO Southeast Asia Report. MAP Aid to Laos 1959 - 1972

    DTIC Science & Technology

    1973-06-25

    to the RLG military, i.e., both FAR and Forces Armee Neutralistes (FAN). 3 Each of the five Military Regions had a field ARMA, who...made to increase the manpower and training status of 3 the Laotian forces. Combined French-U.S. training began on 1 September 1959 with 12 U.S. Field ...For example, the CAS Meo guerrillas harassed Pathet Lao forces in the PDJ region of Central Laos. In addition to

  14. Morphological and molecular variation in Tylototriton (Caudata: Salamandridae) in Laos, with description of a new species.

    PubMed

    Phimmachak, Somphouthone; Aowphol, Anchalee; Stuart, Bryan L

    2015-08-24

    The salamandrid genus Tylototriton is poorly known in Laos, with one described species and unverified reports of two others. We undertook new fieldwork and obtained samples of Tylototriton at six localities across northern Laos during 2009-2013. Bayesian phylogenetic analysis of mitochondrial DNA, principal component analyses of 13 mensural characters, and qualitative morphological comparisons with samples from across the geographic range of Tylototriton were performed. Samples from Laos fell into four molecular and morphological groups, consisting of T. notialis, T. panhai, T. anguliceps, and a fourth lineage that is hypothesized here to be an undescribed species. Tylototriton podichthys sp. nov. is distinguished from its congeners by having distinct mitochondrial DNA haplotypes and in characteristics of the glandular skin on the head and body, shape of the rib nodules, and coloration of the body and limbs. This study expands the number of confirmed Tylototriton species in Laos from one to four, with the description of one species and extension of the ranges of T. panhai and T. anguliceps to Laos. An improved understanding of the geographic ranges of T. podichthys sp. nov. and T. anguliceps within Laos is needed.

  15. Socioeconomic determinants of nutritional status of children in Lao PDR: effects of household and community factors.

    PubMed

    Kamiya, Yusuke

    2011-08-01

    The prevalence of undernutrition among Lao children is among the highest in the region. However, the determinants of childhood undernutrition in Laos have not been fully analyzed. This paper, using the dataset of the Lao Multiple Indicator Cluster Survey 3, which is a nationally-representative sample in Laos, investigated the effects of socioeconomic factors at both household and community levels on the nutritional status of children. In the estimation, a multilevel linear model with random-intercepts was used for estimating the determinants of child anthropometric indices. The empirical results revealed that children from households in southern Laos and from ethnic minority groups were less-nourished. Level of education of parents, attitudes of mothers towards domestic violence, assets of household, local health services, and the condition of sanitation and water were considered to be important determinants of nutritional status of children. The pattern of growth-faltering in children by age was identified. Children aged 12-59 months were less-nourished than those aged 0-11 months. The empirical results were consistent with the collective household model which incorporates a decision-making process within the household. Since there is scarce evidence about the predictors of childhood undernutrition in Laos, the findings of this study will serve as a benchmark for future research.

  16. Lysyl oxidase in colorectal cancer.

    PubMed

    Cox, Thomas R; Erler, Janine T

    2013-11-15

    Colorectal cancer is the third most prevalent form of cancer worldwide and fourth-leading cause of cancer-related mortality, leading to ~600,000 deaths annually, predominantly affecting the developed world. Lysyl oxidase is a secreted, extracellular matrix-modifying enzyme previously suggested to act as a tumor suppressor in colorectal cancer. However, emerging evidence has rapidly implicated lysyl oxidase in promoting metastasis of solid tumors and in particular colorectal cancer at multiple stages, affecting tumor cell proliferation, invasion, and angiogenesis. This emerging research has stimulated significant interest in lysyl oxidase as a strong candidate for developing and deploying inhibitors as functional efficacious cancer therapeutics. In this review, we discuss the rapidly expanding body of knowledge concerning lysyl oxidase in solid tumor progression, highlighting recent advancements in the field of colorectal cancer.

  17. Respiratory burst oxidase of fertilization.

    PubMed Central

    Heinecke, J W; Shapiro, B M

    1989-01-01

    Partially reduced oxygen species are toxic, yet sea urchin eggs synthesize H2O2 in a "respiratory burst" at fertilization, as an extracellular oxidant to crosslink their protective surface envelopes. To study the biochemical mechanism for H2O2 production, we have isolated an NADPH-specific oxidase fraction from homogenates of unfertilized Strongylocentrotus purpuratus eggs that produces H2O2 when stimulated with Ca2+ and MgATP2-. Concentrations of free Ca2+ previously implicated in regulation of egg activation modulate the activity of the oxidase. Inhibitors were used to test the relevance of this oxidase to the respiratory burst of fertilization. Procaine, two phenothiazines, and N-ethylmaleimide (but not iodoacetamide) inhibited H2O2 production by the oxidase fraction and oxygen consumption by activated eggs. The ATP requirement suggested that protein kinase activity might regulate the respiratory burst of fertilization; consonant with this hypothesis, H-7 and staurosporine were inhibitory. The respiratory burst oxidase of fertilization is an NADPH:O2 oxidoreductase that appears to be regulated by a protein kinase; although it bears a remarkable resemblance to the neutrophil oxidase, unlike the latter it does not form O2- as its initial product. PMID:2537493

  18. Sodium iron EDTA and ascorbic acid, but not polyphenol oxidase treatment, counteract the strong inhibitory effect of polyphenols from brown sorghum on the absorption of fortification iron in young women.

    PubMed

    Cercamondi, Colin I; Egli, Ines M; Zeder, Christophe; Hurrell, Richard F

    2014-02-01

    In addition to phytate, polyphenols (PP) might contribute to low Fe bioavailability from sorghum-based foods. To investigate the inhibitory effects of sorghum PP on Fe absorption and the potential enhancing effects of ascorbic acid (AA), NaFeEDTA and the PP oxidase enzyme laccase, we carried out three Fe absorption studies in fifty young women consuming dephytinised Fe-fortified test meals based on white and brown sorghum varieties with different PP concentrations. Fe absorption was measured as the incorporation of stable Fe isotopes into erythrocytes. In study 1, Fe absorption from meals with 17 mg PP (8·5%) was higher than that from meals with 73 mg PP (3·2%) and 167 mg PP (2·7%; P< 0·001). Fe absorption from meals containing 73 and 167 mg PP did not differ (P= 0·9). In study 2, Fe absorption from NaFeEDTA-fortified meals (167 mg PP) was higher than that from the same meals fortified with FeSO₄ (4·6 v. 2·7%; P< 0·001), but still it was lower than that from FeSO₄-fortified meals with 17 mg PP (10·7%; P< 0·001). In study 3, laccase treatment decreased the levels of PP from 167 to 42 mg, but it did not improve absorption compared with that from meals with 167 mg PP (4·8 v. 4·6%; P= 0·4), whereas adding AA increased absorption to 13·6% (P< 0·001). These findings suggest that PP from brown sorghum contribute to low Fe bioavailability from sorghum foods and that AA and, to a lesser extent, NaFeEDTA, but not laccase, have the potential to overcome the inhibitory effect of PP and improve Fe absorption from sorghum foods.

  19. King cobra (Ophiophagus hannah) venom L-amino acid oxidase induces apoptosis in PC-3 cells and suppresses PC-3 solid tumor growth in a tumor xenograft mouse model.

    PubMed

    Lee, Mui Li; Fung, Shin Yee; Chung, Ivy; Pailoor, Jayalakshmi; Cheah, Swee Hung; Tan, Nget Hong

    2014-01-01

    King cobra (Ophiophagus hannah) venom L-amino acid oxidase (OH-LAAO), a heat stable enzyme, has been shown to exhibit very potent anti-proliferative activity against human breast and lung tumorigenic cells but not in their non-tumorigenic counterparts. We further examine its in vitro and in vivo anti-tumor activity in a human prostate adenocarcinoma (PC-3) model. OH-LAAO demonstrated potent cytotoxicity against PC-3 cells with IC50 of 0.05 µg/mL after 72 h incubation in vitro. It induced apoptosis as evidenced with an increase in caspase-3/7 cleavages and an increase in annexin V-stained cells. To examine its in vivo anti-tumor activity, we treated PC-3 tumor xenograft implanted subcutaneously in immunodeficient NU/NU (nude) mice with 1 µg/g OH-LAAO given intraperitoneally (i.p.). After 8 weeks of treatment, OH-LAAO treated PC-3 tumors were markedly inhibited, when compared to the control group (P <0.05). TUNEL staining analysis on the tumor sections showed a significantly increase of apoptotic cells in the LAAO-treated animals. Histological examinations of the vital organs in these two groups showed no significant differences with normal tissues, indicating no obvious tissue damage. The treatment also did not cause any significant changes on the body weight of the mice during the duration of the study. These observations suggest that OH-LAAO cytotoxic effects may be specific to tumor xenografts and less to normal organs. Given its potent anti-tumor activities shown in vitro as well as in vivo, the king cobra venom LAAO can potentially be developed to treat prostate cancer and other solid tumors.

  20. Abscisic acid and aldehyde oxidase activity in maize ear leaf and grain relative to post-flowering photosynthetic capacity and grain-filling rate under different water/nitrogen treatments.

    PubMed

    Qin, Shujun; Zhang, Zongzheng; Ning, Tangyuan; Ren, Shizhong; Su, Licheng; Li, Zengjia

    2013-09-01

    This study investigated changes in leaf abscisic acid (ABA) concentrations and grain ABA concentrations in two maize cultivars and analyzed the following relationships under different water/nitrogen treatments: leaf ABA concentrations and photosynthetic parameters; leaf ABA concentrations and grain ABA concentrations; leaf/grain ABA concentrations and grain-filling parameters; and aldehyde oxidase (AO, EC 1.2.3.1) activities and ABA concentrations. The ear leaf average AO activities and ABA concentrations were lower in the controlled release urea treatments compared with the conventional urea treatments. The average AO activities in the grains were higher in the controlled release urea treatments, and the ABA concentrations were significantly increased at 11-30 DAF. The Pn and ABA concentrations in ear leaves were negatively correlated. And the Gmean were positively correlated with the grain ABA concentrations at 11-30 DAF and negatively correlated with the leaf ABA concentrations at 20 and 40-50 DAF. The grain ABA concentrations and leaf ABA concentrations were positively correlated. Thus, the Gmean were closely related to the AO activities and to the ear leaf and grain ABA concentrations. As compared to other treatments, the subsoiling and controlled release urea treatment promoted the uptake of water and nitrogen by maize, increased the photosynthetic capacity of the ear leaves, increased the grain-filling rate, and improved the movement of photosynthetic assimilates toward the developing grains. In the cultivar Z958, higher ABA concentrations in grains at 11-30 DAF and lower ABA concentrations in ear leaves during the late grain-filling stage, resulted in higher grain-filling rate and increased accumulation of photosynthetic products (relative to the cultivar D3).

  1. Purification of xanthine dehydrogenase and sulfite oxidase from chicken liver.

    PubMed

    Ratnam, K; Brody, M S; Hille, R

    1996-05-01

    Xanthine dehydrogenase and sulfite oxidase from chicken liver are oxomolybdenum enzymes which catalyze the oxidation of xanthine to uric acid and sulfite to sulfate, respectively. Independent purification protocols have been previously described for both enzymes. Here we describe a procedure by which xanthine dehydrogenase and sulfite oxidase are purified simultaneously from the same batch of fresh chicken liver. Also, unlike the protocols described earlier, this procedure avoids the use of acetone extraction as well as a heat step, thus minimizing damage to the molybdenum centers of the enzymes.

  2. Involvement of NADH Oxidase in Biofilm Formation in Streptococcus sanguinis

    PubMed Central

    Ge, Xiuchun; Shi, Xiaoli; Shi, Limei; Liu, Jinlin; Stone, Victoria; Kong, Fanxiang; Kitten, Todd; Xu, Ping

    2016-01-01

    Biofilms play important roles in microbial communities and are related to infectious diseases. Here, we report direct evidence that a bacterial nox gene encoding NADH oxidase is involved in biofilm formation. A dramatic reduction in biofilm formation was observed in a Streptococcus sanguinis nox mutant under anaerobic conditions without any decrease in growth. The membrane fluidity of the mutant bacterial cells was found to be decreased and the fatty acid composition altered, with increased palmitic acid and decreased stearic acid and vaccenic acid. Extracellular DNA of the mutant was reduced in abundance and bacterial competence was suppressed. Gene expression analysis in the mutant identified two genes with altered expression, gtfP and Idh, which were found to be related to biofilm formation through examination of their deletion mutants. NADH oxidase-related metabolic pathways were analyzed, further clarifying the function of this enzyme in biofilm formation. PMID:26950587

  3. NADPH Oxidases in Vascular Pathology

    PubMed Central

    Konior, Anna; Schramm, Agata; Czesnikiewicz-Guzik, Marta

    2014-01-01

    Abstract Significance: Reactive oxygen species (ROS) play a critical role in vascular disease. While there are many possible sources of ROS, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases play a central role. They are a source of “kindling radicals,” which affect other enzymes, such as nitric oxide synthase endothelial nitric oxide synthase or xanthine oxidase. This is important, as risk factors for atherosclerosis (hypertension, diabetes, hypercholesterolemia, and smoking) regulate the expression and activity of NADPH oxidases in the vessel wall. Recent Advances: There are seven isoforms in mammals: Nox1, Nox2, Nox3, Nox4, Nox5, Duox1 and Duox2. Nox1, Nox2, Nox4, and Nox5 are expressed in endothelium, vascular smooth muscle cells, fibroblasts, or perivascular adipocytes. Other homologues have not been found or are expressed at very low levels; their roles have not been established. Nox1/Nox2 promote the development of endothelial dysfunction, hypertension, and inflammation. Nox4 may have a role in protecting the vasculature during stress; however, when its activity is increased, it may be detrimental. Calcium-dependent Nox5 has been implicated in oxidative damage in human atherosclerosis. Critical Issues: NADPH oxidase-derived ROS play a role in vascular pathology as well as in the maintenance of normal physiological vascular function. We also discuss recently elucidated mechanisms such as the role of NADPH oxidases in vascular protection, vascular inflammation, pulmonary hypertension, tumor angiogenesis, and central nervous system regulation of vascular function and hypertension. Future Directions: Understanding the role of individual oxidases and interactions between homologues in vascular disease is critical for efficient pharmacological regulation of vascular NADPH oxidases in both the laboratory and clinical practice. Antioxid. Redox Signal. 20, 2794–2814. PMID:24180474

  4. Anatomically modern human in Southeast Asia (Laos) by 46 ka

    PubMed Central

    Demeter, Fabrice; Shackelford, Laura L.; Bacon, Anne-Marie; Duringer, Philippe; Westaway, Kira; Sayavongkhamdy, Thongsa; Braga, José; Sichanthongtip, Phonephanh; Khamdalavong, Phimmasaeng; Ponche, Jean-Luc; Wang, Hong; Lundstrom, Craig; Patole-Edoumba, Elise; Karpoff, Anne-Marie

    2012-01-01

    Uncertainties surround the timing of modern human emergence and occupation in East and Southeast Asia. Although genetic and archeological data indicate a rapid migration out of Africa and into Southeast Asia by at least 60 ka, mainland Southeast Asia is notable for its absence of fossil evidence for early modern human occupation. Here we report on a modern human cranium from Tam Pa Ling, Laos, which was recovered from a secure stratigraphic context. Radiocarbon and luminescence dating of the surrounding sediments provide a minimum age of 51–46 ka, and direct U-dating of the bone indicates a maximum age of ∼63 ka. The cranium has a derived modern human morphology in features of the frontal, occipital, maxillae, and dentition. It is also differentiated from western Eurasian archaic humans in aspects of its temporal, occipital, and dental morphology. In the context of an increasingly documented archaic–modern morphological mosaic among the earliest modern humans in western Eurasia, Tam Pa Ling establishes a definitively modern population in Southeast Asia at ∼50 ka cal BP. As such, it provides the earliest skeletal evidence for fully modern humans in mainland Southeast Asia. PMID:22908291

  5. Anatomically modern human in Southeast Asia (Laos) by 46 ka.

    PubMed

    Demeter, Fabrice; Shackelford, Laura L; Bacon, Anne-Marie; Duringer, Philippe; Westaway, Kira; Sayavongkhamdy, Thongsa; Braga, José; Sichanthongtip, Phonephanh; Khamdalavong, Phimmasaeng; Ponche, Jean-Luc; Wang, Hong; Lundstrom, Craig; Patole-Edoumba, Elise; Karpoff, Anne-Marie

    2012-09-04

    Uncertainties surround the timing of modern human emergence and occupation in East and Southeast Asia. Although genetic and archeological data indicate a rapid migration out of Africa and into Southeast Asia by at least 60 ka, mainland Southeast Asia is notable for its absence of fossil evidence for early modern human occupation. Here we report on a modern human cranium from Tam Pa Ling, Laos, which was recovered from a secure stratigraphic context. Radiocarbon and luminescence dating of the surrounding sediments provide a minimum age of 51-46 ka, and direct U-dating of the bone indicates a maximum age of ~63 ka. The cranium has a derived modern human morphology in features of the frontal, occipital, maxillae, and dentition. It is also differentiated from western Eurasian archaic humans in aspects of its temporal, occipital, and dental morphology. In the context of an increasingly documented archaic-modern morphological mosaic among the earliest modern humans in western Eurasia, Tam Pa Ling establishes a definitively modern population in Southeast Asia at ~50 ka cal BP. As such, it provides the earliest skeletal evidence for fully modern humans in mainland Southeast Asia.

  6. Intracellular substrates of a heme-containing ascorbate oxidase in Pleurotus ostreatus.

    PubMed

    Lee, Seung-Rock; Joo, Woo-Jeong; Baek, Yong-Un; Lee, Youn-Kyong; Yu, Seong-Woon; Kim, Yeon-Ran; Chay, Kee-Oh; Cho, Seung-Hyun; Kang, Sa-Ouk; Rang, Sa-Ouk

    2009-04-01

    A novel heme-containing ascorbate oxidase isolated from oyster mushroom, Pleurotus ostreatus, catalyzes oxidation of ascorbic acid (Kim et al., 1996). In this report, we describe the identification of intracellular substrates of the enzyme in the mushroom. Six compounds, which can serve as substrate of the heme-containing ascorbate oxidase, were identified as L-ascorbic acid, D-erythroascorbic acid, 5-O-(alpha-D-glucopyranosyl)-D-erythroascorbic acid, 5-O-(alpha-D-xylopyranosyl)-D-erythroascorbic acid, 5-methyl-5-O-(alpha-D-gluco-pyranosyl)-D-erythroascorbic acid, and 5-methyl-5-O-(alpha-D-xylopyranosyl)-D-erythroascorbic acid. All of the compounds were oxidized at a significant rate by the heme-containing ascorbate oxidase. Oxidation of the compounds produced equimolar amounts of hydrogen peroxide per mole of substrate.

  7. Individual variation in hepatic aldehyde oxidase activity.

    PubMed

    Al-Salmy, H S

    2001-04-01

    Aldehyde oxidase (AO) is a molybdo-flavo enzyme expressed predominantly in the liver, lung, and kidney. AO plays a major role in oxidation of aldehydes, as well as oxidation of various N-heterocyclic compounds of pharmacological and toxicological importance including antiviral (famciclovir), antimalarial (quinine), antitumour (methotrexate), and nicotine. The aim of this study was to investigate cytosolic aldehyde oxidase activity in human liver. Cytosolic AO was characterised using both the metabolism of N-[(2-dimethylamino)ethyl] acridine-4-carboxamide (DACA) and benzaldehyde to form DACA-9(10H)-acridone (quantified by HPLC with fluorescence detection) and benzoic acid (quantified spectrophotometrically). Thirteen livers (10 female, 3 male) were examined. The intrinsic clearance (Vmax/Km) of DACA varied 18-fold (0.03-0.50 m/min/mg). Vmax ranged from 0.20-3.10 nmol/ min/mg, and Km ranged from 3.5-14.2 microM. In the same specimens, the intrinsic clearance for benzaldehyde varied 5-fold (0.40-1.8 ml/min/mg). Vmax ranged from 3.60-12.6 nmol/min/mg and Km ranged from 3.6-14.6 microM. Furthermore, there were no differences in AO activity between male and female human livers, nor was there any relationship to age of donor (range 29-73 years), smoking status, or disease status. In conclusion, our results showed that there are variations in AO activity in human liver. These variations in aldehyde oxidase activity might reflect individual variations or they might be due to AO stability during processing and storage.

  8. Drawing on Students' Experiences, Cultures and Languages to Develop English Language Writing: Perspectives from Three Lao Heritage Middle School Students

    ERIC Educational Resources Information Center

    Souryasack, Rassamichanh; Lee, Jin Sook

    2007-01-01

    Lao students have not fared well in the American educational system. Raised in a home culture that emphasizes and values the oral tradition, the acquisition of academic writing skills has been especially problematic even for U.S.-born students of Lao heritage. Recognizing that writing is a critical component for academic success, this study…

  9. First record of Sonotrella Gorochov (Orthoptera: Gryllidae) from Laos, with description of a new species.

    PubMed

    Liu, Hao-Yu; Zhang, Dong-Xiao; Shi, Fu-Ming

    2016-05-23

    The genus Sonotrella Gorochov, 1988 is recorded to Laos for the first time. A new species is described and illustrated, S. (Sonotrella) laosensis sp. nov. (type locality: Laos). A distribution map of the species of Sonotrella (Sonotrella) and a key to the subgenera of Sonotrella worldwide are given.

  10. 3 CFR - Presidential Determination for the Lao People's Democratic Republic Under Section 2(b)(2) of the...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 3 The President 1 2010-01-01 2010-01-01 false Presidential Determination for the Lao People's Democratic Republic Under Section 2(b)(2) of the Export-Import Bank Act of 1945, as amended Presidential Documents Other Presidential Documents Presidential Determination No. 2009-21 of June 12, 2009 Presidential Determination for the Lao...

  11. Preparing for the introduction of hospital autonomy in Laos: an assessment of current situation and suggestions for policy-making.

    PubMed

    Geng, Jinsong; Yu, Hao; Chen, Yingyao

    2016-04-01

    The National Assembly of Lao People's Democratic Republic (Laos) approved the Health Sector Reform Strategy in 2012, which called for an assessment as to whether Laos should introduce hospital autonomy, and if so, in which ways. The purpose of this study is to assess the status quo of hospital governance in Laos and propose policy suggestions for hospital autonomy in the country. We formulated an analytic framework for hospital autonomy based on previous work by other researchers, collected qualitative data through key informant interviews and focus group discussions, and also performed secondary data analysis. Public hospitals in Laos enjoyed some informal autonomy with little accountability and Laos is facing key challenges of hospital governance. As a result, introducing hospital autonomy in Laos could bring risks, benefits and debates. Before Laos decides on granting autonomy to its public hospitals, we strongly suggest that the government do pilot in selected public hospitals with well-regulated governance framework first and conduct rigorous evaluations to examine whether the granted autonomy leads to the intended social goals of equity, quality, efficiency and sustainability. We recommend residual claimants should be monitored by the government and by the society with open and transparent approach, and active measures should be taken to improve performance and ensure social functions. The study findings may also provide some suggestions for low- and middle-income countries, which are contemplating the introduction of hospital autonomy in the public sector. Copyright © 2015 John Wiley & Sons, Ltd.

  12. 8 CFR 245.21 - Adjustment of status of certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). 245.21 Section 245.21 Aliens and... ADMITTED FOR PERMANENT RESIDENCE § 245.21 Adjustment of status of certain nationals of Vietnam, Cambodia... a lawful permanent resident, a native or citizen of Vietnam, Cambodia, or Laos who: (1)...

  13. 8 CFR 1245.21 - Adjustment of status of certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). 1245.21 Section 1245.21 Aliens... certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). (a) Eligibility. The Service may adjust the status to that of a lawful permanent resident, a native or citizen of...

  14. 8 CFR 245.21 - Adjustment of status of certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). 245.21 Section 245.21 Aliens and... ADMITTED FOR PERMANENT RESIDENCE § 245.21 Adjustment of status of certain nationals of Vietnam, Cambodia... a lawful permanent resident, a native or citizen of Vietnam, Cambodia, or Laos who: (1)...

  15. 8 CFR 1245.21 - Adjustment of status of certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). 1245.21 Section 1245.21 Aliens... certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). (a) Eligibility. The Service may adjust the status to that of a lawful permanent resident, a native or citizen of...

  16. 8 CFR 245.21 - Adjustment of status of certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). 245.21 Section 245.21 Aliens and... ADMITTED FOR PERMANENT RESIDENCE § 245.21 Adjustment of status of certain nationals of Vietnam, Cambodia... that of a lawful permanent resident, a native or citizen of Vietnam, Cambodia, or Laos who: (1)...

  17. 8 CFR 245.21 - Adjustment of status of certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). 245.21 Section 245.21 Aliens and... ADMITTED FOR PERMANENT RESIDENCE § 245.21 Adjustment of status of certain nationals of Vietnam, Cambodia... a lawful permanent resident, a native or citizen of Vietnam, Cambodia, or Laos who: (1)...

  18. 8 CFR 1245.21 - Adjustment of status of certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). 1245.21 Section 1245.21 Aliens... certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). (a) Eligibility. The Service may adjust the status to that of a lawful permanent resident, a native or citizen of...

  19. 8 CFR 1245.21 - Adjustment of status of certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). 1245.21 Section 1245.21 Aliens... certain nationals of Vietnam, Cambodia, and Laos (section 586 of Public Law 106-429). (a) Eligibility. The Service may adjust the status to that of a lawful permanent resident, a native or citizen of...

  20. Signalling L2 Centrality, Maintaining L1 Dominance: Teacher Language Choice in an Ethnic Minority Primary Classroom in the Lao PDR

    ERIC Educational Resources Information Center

    Cincotta-Segi, Angela Rose

    2011-01-01

    Although the Lao People's Democratic Republic has speakers of up to 230 different languages belonging to four ethnolinguistic families, the Lao Government's policy as stated in its Education Law is that Lao is the official language of education at all levels. This creates a challenging situation for teachers in ethnic minority villages throughout…

  1. Talking in, Talking around and Talking about the L2: Three Literacy Teaching Responses to L2 Medium of Instruction in the Lao PDR

    ERIC Educational Resources Information Center

    Cincotta-Segi, Angela

    2011-01-01

    With speakers of over one hundred languages, the Lao PDR is one of the most ethnically and linguistically diverse nations in Southeast Asia. However, its education policy stipulates that Lao is the language of education at all levels of schooling. Non-ethnic Lao students are thus required to learn literacy in a language which they do not speak.…

  2. A new Philautus (Anura: Rhacophoridae) from northern Laos allied to P. abditus Inger, Orlov & Darevsky, 1999.

    PubMed

    Stuart, Bryan L; Phimmachak, Somphouthone; Seateun, Sengvilay; Sheridan, Jennifer A

    2013-12-03

    The small rhacophorid frog Philautus abditus is geographically restricted to central Vietnam and adjacent Cambodia. Our fieldwork in northern Laos resulted in the discovery of a Philautus species that very closely resembles P. abditus, but is at least 330 km from the nearest known locality of that species. The Laos population differs from P. abditus in mitochondrial DNA and coloration, and is described here as a new species. Philautus nianeae sp. nov. is distinguished from its congeners by having the combination of a hidden tympanum; no nuptial pads; smooth skin; large black spots on the hidden surfaces of the hind limbs; light venter with dark spotting; and a bronze iris. A second species of Philautus from northern Laos, P. petilus, is transferred on the basis of morphology to the genus Theloderma. 

  3. Prevalence and Factors Associated with Opisthorchis viverrini Infection in Khammouane Province, Lao PDR.

    PubMed

    Saiyachak, Khamphanavanh; Tongsotsang, Sutthiporn; Saenrueang, Thitima; Moore, Malcolm A; Promthet, Supannee

    2016-01-01

    Opisthorchis viverrini (OV) liver flukes are common parasites found in central and southern Laos and constitute a major public health problem in the country. Laos people continue to have the habit of extensively consuming raw or half-cooked fish which are intermediate hosts. This study aimed to study the prevalence and factors associated with OV infection in the population of Thakek district, Khammouane Province. This cross-sectional analytic study covered 237 subjects who filled out structured questionnaires. Fecal examination for OV infection was performed by Kato's thick smear method. Data analysis was carried out using STATA Version 10.0. Multiple logistic regression was applied. The results showed that the infection rate of OV was 54.8 %. Factors associated with OV infections were gender, a habit of defecation in fields and raw fish (goi bplaa dip) consumption. Opisthorchiasis and associated cholangiocarcinoma development thus appear to remain as important concerns in Laos.

  4. Expression of alternative oxidase in tomato

    SciTech Connect

    Kakefuda, M.; McIntosh, L. )

    1990-05-01

    Tomato fruit ripening is characterized by an increase in ethylene biosynthesis, a burst in respiration (i.e. the climacteric), fruit softening and pigmentation. As whole tomatoes ripened from mature green to red, there was an increase in the alternative oxidase capacity. Aging pink tomato slices for 24 and 48 hrs also showed an increase of alternative oxidase and cytochrome oxidase capacities. Monoclonal antibodies prepared to the Sauromatum guttatum alternative oxidase were used to follow the appearance of alternative oxidase in tomato fruits. There is a corresponding increase in a 36kDa protein with an increase in alternative oxidase capacity. Effects of ethylene and norbornadiene on alternative oxidase capacity were also studied. We are using an alternative oxidase cDNA clone from potato to study the expression of mRNA in ripening and wounded tomatoes to determine if the gene is transcriptionally regulated.

  5. Perceived illness drives participation in mass deworming campaigns in Laos.

    PubMed

    Phongluxa, Khampheng; van Eeuwijk, Peter; Soukhathammavong, Phonepasong Ayé; Akkhavong, Kongsap; Odermatt, Peter

    2015-01-01

    Multiple helminth infections are very common in communities of southern Laos. Preventive chemotherapy in combination with health education is the mainstay of control. We assessed the knowledge, perceptions and practices of rural communities related to endemic helminthiasis and their control during a mass drug administration (MDA) campaign. Short interviews with household heads (n=192), direct observations and discussions with attendees of MDAs, and in-depth interviews with local opinion leaders (n=21) were carried out. Quantitative and qualitative data analysis was performed. Results showed that opinion leaders and villagers were well aware of the importance of attending MDA. Leaders perceived the effectiveness of MDA against severe schistosomiasis and appreciated that it was provided for free and in their village. They encouraged villagers to attend it. Anticipated adverse events of praziquantel was a barrier for participation. A majority of leaders purchased deworming tablet (mebendazole, albendazole) in a local pharmacy for deworming when MDA is absent in their villages (19/21). Most leaders (20/21) had a good knowledge on severe schistosomiasis though only a few of them (5/21) described its cause correctly. They knew little about the disease consequences of liver fluke (3/21) and soil-transmitted helminth (4/21) infections but more about their causes. A high risk for worm infection was observed: consumption of raw or insufficiently cooked fish (100%), frequent physical contacts with Mekong River water (76.0%) and low number of latrines (14.5%). In conclusion, MDA is widely accepted in affected communities. Avoiding severe schistosomiasis was the main motivation to comply. Participation rates increased significantly with drugs provided free of charge in the villages. Better knowledge on the consequences of worm infections and on its modes of transmission will foster the distribution and acceptance of appropriate preventive treatment and other measures in

  6. Impact Crater of the Australasian Tektites, Southern Laos

    NASA Astrophysics Data System (ADS)

    Sieh, K.; Herrin, J. S.; Wiwegwin, W.; Charusiri, P.; Singer, B. S.; Singsomboun, K.; Jicha, B. R.

    2015-12-01

    The Australasian strewn field, a horizon of glassy clasts formed of molten ejecta from the impact of a bolide about 770,000 years ago, covers about a tenth of the Earth - from Indochina to Australia and from the Indian to western Pacific oceans. The distribution of chemical and physical characteristics of these tektites implies a very large impact somewhere in central Indochina. A half-century of unsuccessful searching for the impact crater implies obscuration by either erosion or burial. Geomorphological and stratigraphic evidence suggests that the crater lies buried beneath lavas and cinder cones of a 100-km wide volcanic shield centered atop the Bolaven Plateau of southern Laos. One critical test of this hypothesis, using precise 40Ar/39Ar dating, is now in progress - are these highly weathered basalts younger than the tektites? Although volcanic rocks cover most of the area proximal to our purported impact site, a thick, crudely bedded, bouldery to pebbly breccia that crops out southeast of the obscured crater rim appears to be part of an ejecta blanket. The basal unit of this fining-upward sequence comprises large boulders of late-Mesozoic sandstone bedrock that display in situ shattering. This implies emplacement ballistically rather than by debris-flow. Old surfaces in the surrounding region (as others have noted) and on the Plateau have a mantle of pebbly, detrital lateritic debris that in its upper 15 cm contains angular tektite fragments. We hypothesize that this debris is a proximal fall bed produced by shock-induced comminution and ejection of a lateritic soil that covered the Plateau bedrock. Deposition was nearly complete when sparse tektite fragments ejected from nearer the center of the impact began to land. At many sites this pebbly, lateritic bed is overlain by a thick silty bed that others have associated with aeolian erosion of a barren, incinerated tropical landscape. See Herrin et al (this meeting) for more on the volcanic rocks.

  7. Stakeholders' opinions about a tobacco policy in Lao PDR

    PubMed Central

    Tomson, Tanja; Akkhavong, Kongsap; Gilljam, Hans

    2009-01-01

    The global epidemic of tobacco smoking is expected to impact hardest in low- and middle- income countries (LMIC). There is a lack of understanding regarding the policy environments within which tobacco control policies are being introduced particularly in LMIC. This study aims at exploring key stakeholders' beliefs about a tobacco policy in Lao PDR. This is a qualitative case study with a standardised open-ended questionnaire answered by eleven stakeholders in leading positions within different ministries and the media, donors and NGOs. Themes included the perception of tobacco among professionals, awareness of tobacco as a public health issue, importance of inter-sectoral cooperation, and obstacles faced in implementing policies. The research team included both outsiders and an insider. Analysis was done using the case and cross-case analysis. Among the respondents there was consensus regarding the positive impact of a national tobacco policy with the exception of the representative from the Ministry of Agriculture. Stakeholders identified education, awareness creation through media and law enforcement as important interventions, followed by taxation. Education should be diversified in the way it should be delivered. It was emphasized that people in rural areas and minority groups need tailored made approaches. A major limiting factor in moving tobacco control forward in LMIC was stated to be the lack of funding. The refusal by tobacco industry to participate in the study is noteworthy. It is essential to draft a national tobacco policy that can help the government to increase taxes, and create adequate provisions for the enforcement of tobacco laws and regulations. PMID:19144186

  8. Inhibition of apple polyphenol oxidase activity by procyanidins and polyphenol oxidation products.

    PubMed

    Le Bourvellec, Carine; Le Quéré, Jean-Michel; Sanoner, Philippe; Drilleau, Jean-François; Guyot, Sylvain

    2004-01-14

    The rate of consumption of dissolved oxygen by apple polyphenol oxidase in cider apple juices did not correlate with polyphenol oxidase activity in the fruits and decreased faster than could be explained by the decrease of its polyphenolic substrates. The kinetics parameters of a crude polyphenol oxidase extract, prepared from apple (Braeburn cultivar), were determined using caffeoylquinic acid as a substrate. Three apple procyanidin fractions of n 80, 10.5, and 4 were purified from the parenchyma of cider apples of various cultivars. Procyanidins, caffeoylquinic acid, (-)-epicatechin, and a mixture of caffeoylquinic acid and (-)-epicatechin were oxidized by reaction with caffeoylquinic acid o-quinone in order to form oxidation products. All the fractions were evaluated for their inhibitory effect on PPO activity. Native procyanidins inhibited polyphenol oxidase activity, the inhibition intensity increasing with n. The polyphenol oxidase activity decreased by 50% for 0.026 g/L of the fraction of n 80, 0.17 g/L of the fraction of n 10.5, and 1 g/L of the fraction of n 4. The inhibitory effect of oxidized procyanidins was twice that of native procyanidins. Oxidation products of caffeoylquinic acid and (-)-epicatechin also inhibited polyphenol oxidase.

  9. Polyphenol oxidase from yacon roots (Smallanthus sonchifolius).

    PubMed

    Neves, Valdir Augusto; da Silva, Maraiza Aparecida

    2007-03-21

    Polyphenol oxidase (E.C. 1.14.18.1) (PPO) extracted from yacon roots (Smallanthus sonchifolius) was partially purified by ammonium sulfate fractionation and separation on Sephadex G-100. The enzyme had a molecular weight of 45 490+/-3500 Da and Km values of 0.23, 1.14, 1.34, and 5.0 mM for the substrates caffeic acid, chlorogenic acid, 4-methylcatechol, and catechol, respectively. When assayed with resorcinol, DL-DOPA, pyrogallol, protocatechuic, p-coumaric, ferulic, and cinnamic acids, catechin, and quercetin, the PPO showed no activity. The optimum pH varied from 5.0 to 6.6, depending on substrate. PPO activity was inhibited by various phenolic and nonphenolic compounds. p-Coumaric and cinnamic acids showed competitive inhibition, with Ki values of 0.017 and 0.011 mM, respectively, using chlorogenic acid as substrate. Heat inactivation from 60 to 90 degrees C showed the enzyme to be relatively stable at 60-70 degrees C, with progressive inactivation when incubated at 80 and 90 degrees C. The Ea (apparent activation energy) for inactivation was 93.69 kJ mol-1. Sucrose, maltose, glucose, fructose, and trehalose at high concentrations appeared to protect yacon PPO against thermal inactivation at 75 and 80 degrees C.

  10. Urate oxidase knockdown decreases oxidative stress in a murine hepatic cell line

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Humans, birds, and some primates do not express the uric acid degrading enzyme urate oxidase (UOX) and, as a result, have plasma uric acid concentrations higher than UOX expressing animals. Although high uric acid concentrations are suggested to increase the antioxidant defense system and provide a...

  11. Hyper-responsive Toll-like receptor 7 and 9 activation in NADPH oxidase-deficient B lymphoblasts.

    PubMed

    McLetchie, Shawna; Volpp, Bryan D; Dinauer, Mary C; Blum, Janice S

    2015-12-01

    Chronic granulomatous disease (CGD) is an inherited immunodeficiency linked with mutations in the multi-subunit leucocyte NADPH oxidase. Myeloid-derived phagocytic cells deficient in NADPH oxidase fail to produce sufficient levels of reactive oxygen species to clear engulfed pathogens. In this study we show that oxidase also influences B-cell functions, including responses to single-stranded RNA or unmethylated DNA by endosomal Toll-like receptors (TLRs) 7 and 9. In response to TLR7/9 ligands, B-cell lines derived from patients with CGD with mutations in either the NADPH oxidase p40(phox) or p47(phox) subunits produced only low levels of reactive oxygen species. Remarkably, cytokine secretion and p38 mitogen-activated protein kinase activation by these oxidase-deficient B cells was significantly increased upon TLR7/9 activation when compared with oxidase-sufficient B cells. Increased TLR responsiveness was also detected in B cells from oxidase-deficient mice. NADPH oxidase-deficient patient-derived B cells also expressed enhanced levels of TLR7 and TLR9 mRNA and protein compared with the same cells reconstituted to restore oxidase activity. These data demonstrate that the loss of oxidase function associated with CGD can significantly impact B-cell TLR signalling in response to nucleic acids with potential repercussions for auto-reactivity in patients.

  12. The Impact of Single Nucleotide Polymorphisms on Human Aldehyde OxidaseS

    PubMed Central

    Hartmann, Tobias; Terao, Mineko; Garattini, Enrico; Teutloff, Christian; Alfaro, Joshua F.; Jones, Jeffrey P.; Leimkühler, Silke

    2012-01-01

    Aldehyde oxidase (AO) is a complex molybdo-flavoprotein that belongs to the xanthine oxidase family. AO is active as a homodimer, and each 150-kDa monomer binds two distinct [2Fe2S] clusters, FAD, and the molybdenum cofactor. AO has an important role in the metabolism of drugs based on its broad substrate specificity oxidizing aromatic aza-heterocycles, for example, N1-methylnicotinamide and N-methylphthalazinium, or aldehydes, such as benzaldehyde, retinal, and vanillin. Sequencing the 35 coding exons of the human AOX1 gene in a sample of 180 Italian individuals led to the identification of relatively frequent, synonymous, missense and nonsense single-nucleotide polymorphisms (SNPs). Human aldehyde oxidase (hAOX1) was purified after heterologous expression in Escherichia coli. The recombinant protein was obtained with a purity of 95% and a yield of 50 μg/l E. coli culture. Site-directed mutagenesis of the hAOX1 cDNA allowed the purification of protein variants bearing the amino acid changes R802C, R921H, N1135S, and H1297R, which correspond to some of the identified SNPs. The hAOX1 variants were purified and compared with the wild-type protein relative to activity, oligomerization state, and metal content. Our data show that the mutation of each amino acid residue has a variable impact on the ability of hAOX1 to metabolize selected substrates. Thus, the human population is characterized by the presence of functionally inactive hAOX1 allelic variants as well as variants encoding enzymes with different catalytic activities. Our results indicate that the presence of these allelic variants should be considered for the design of future drugs. PMID:22279051

  13. Coping with uncertainty during healthcare-seeking in Lao PDR

    PubMed Central

    2013-01-01

    Background Uncertainty is regarded as a central dimension in the experience of illness and in the processes of alleviating it. Few studies from resource-poor settings have investigated this and how it interacts with other factors. This study aims to shed light on how healthcare-seeking develops in the context of multiple medical alternatives and to understand what bearing uncertainty has on this process. Methods The study was conducted in six purposively selected rural communities in Lao PDR. In each community, two focus group discussions were held: first with mothers and then with fathers of children younger than five years old. Eleven in-depth interviews with caregivers of severely sick children were conducted. Subsequently, traditional healers, drug vendors, community health workers, nurses and medical doctors were recruited for interviews or group discussions. The data were transcribed and key themes and similarities were identified. Additional readings were conducted to better understand the interactions of factors during which uncertainty was identified as one of several factors mentioned during interviews and focus group discussions. Results Care-seekers expressed a strong preference for initially seeking local providers. Subsequently, multiple providers were consulted to increase the chances of recovery. This resulted in patients leaving the health facilities before recovery and in ending the recommended treatment regime prematurely. These healthcare-seeking decisions reflect the social significance of being a responsible caregiver and of showing respect for household norms. In general, healthcare-seeking was shrouded in uncertainty when it came to selecting the right provider, the likelihood of finding the real cause of the illness, spending savings on treatments and ultimately the likelihood of recovery. Conclusions Care-seekers’ initial strong preference for local providers irrespective of the providers’ legitimacy indicates the need for a robust

  14. The Effectiveness of Written Corrective Feedback and the Impact Lao Learners' Beliefs Have on Uptake

    ERIC Educational Resources Information Center

    Rummel, Stephanie; Bitchener, John

    2015-01-01

    This article presents the results of a study examining the effectiveness of written corrective feedback (CF) on the simple past tense and the impact beliefs may have on students' uptake of the feedback they receive. A seven-week study was carried out with 42 advanced EFL learners in Vientiane, Laos. Students' beliefs about written CF were first…

  15. The Diversity and Geographical Structure of Orientia tsutsugamushi Strains from Scrub Typhus Patients in Laos.

    PubMed

    Phetsouvanh, Rattanaphone; Sonthayanon, Piengchan; Pukrittayakamee, Sasithon; Paris, Daniel H; Newton, Paul N; Feil, Edward J; Day, Nicholas P J

    2015-01-01

    Orientia tsutsugamushi is the causative agent of scrub typhus, a disease transmitted by Leptotrombidium mites which is responsible for a severe and under-reported public health burden throughout Southeast Asia. Here we use multilocus sequence typing (MLST) to characterize 74 clinical isolates from three geographic locations in the Lao PDR (Laos), and compare them with isolates described from Udon Thani, northeast Thailand. The data confirm high levels of diversity and recombination within the natural O. tsutsugamushi population, and a rate of mixed infection of ~8%. We compared the relationships and geographical structuring of the strains and populations using allele based approaches (eBURST), phylogenetic approaches, and by calculating F-statistics (FST). These analyses all point towards low levels of population differentiation between isolates from Vientiane and Udon Thani, cities which straddle the Mekong River which defines the Lao/Thai border, but with a very distinct population in Salavan, southern Laos. These data highlight how land use, as well as the movement of hosts and vectors, may impact on the epidemiology of zoonotic infections.

  16. Enhancing Laos Students' Understanding of Nature of Science in Physics Learning about Atom for Peace

    ERIC Educational Resources Information Center

    Sengdala, Phoxay; Yuenyong, Chokchai

    2014-01-01

    This paper aimed to study of Grade 12 students' understanding of nature of science in learning about atom for peace through science technology and society (STS) approach. Participants were 51 Grade 12 who study in Thongphong high school Vientiane Capital City Lao PDR, 1st semester of 2012 academic year. This research regarded interpretive…

  17. Profiles of the Highland Lao Communities in the United States. Final Report.

    ERIC Educational Resources Information Center

    Yang, Doua; North, David

    This collection of statistical data on the 90 Highland Lao communities in the United States is designed to help members of those communities and people working in refugee-serving agencies to better assist this refugee group. Information was provided by community leaders, state refugee coordinators, and county human resource officials in 1988.…

  18. The millipede genus Orthomorpha Bollman, 1893 in Laos (Diplopoda, Polydesmida, Paradoxosomatidae), with descriptions of new species

    PubMed Central

    Likhitrakarn, Natdanai; Golovatch, Sergei I.; Panha, Somsak

    2014-01-01

    Abstract The genus Orthomorpha is currently represented in Laos by nine species, including three, O. paviei Brölemann, 1896, O. communis Likhitrakarn, Golovatch & Panha, 2011 and O. cambodjana (Attems, 1953), which are new to the fauna of the country, and further three new to science: O. suberectoides sp. n., O. gladiata sp. n. and O. sutchariti sp. n. PMID:24493962

  19. Indochinese Refugee Experience. Refugees from Vietnam, Laos, and Cambodia in Nova Scotia.

    ERIC Educational Resources Information Center

    Ngo, Xuong, Comp.; Guay, Marcel, Ed.

    Firsthand accounts by refugees from Laos, Cambodia, and Vietnam, telling how they escaped from Indochina and how they are adjusting to life in Canada (and particularly Nova Scotia), form the greater part of this book. Most of the accounts are by Vietnamese. Information is also provided on the history of the Canadian refugee program, and on the…

  20. "We Are Like Orphans": Exploring Narratives of Lao Doctoral Alumni Educated in Sweden

    ERIC Educational Resources Information Center

    Silfver, Ann-Louise; Berge, Britt-Marie

    2016-01-01

    In this article, we explore the narratives of 10 doctoral alumni from Lao People's Democratic Republic (PDR) who underwent graduate training in Sweden. The narratives identify challenges encountered by the alumni but more importantly reveal the agency by which these challenges were overcome. The most important strategy was that of collaborative…

  1. Investigating Learning English Strategies and English Needs of Undergraduate Students at the National University of Laos

    ERIC Educational Resources Information Center

    Souriyavongsa, Thongma; Abidin, Mohamad Jafre Zainol; Sam, Rany; Mei, Leong Lai; Aloysius, Ithayaraj Britto

    2013-01-01

    This paper aims to investigate learning English strategies and the requirement of English needs of the undergraduate students at the National University of Laos (NUOL). The study employed a survey design which involved in administering questionnaires of rating scales, and adapting the items from (Barakat, 2010; Chengbin, 2008; Kathleen A, 2010;…

  2. Lao Newcomers and Mennonite Settlers: A Case Study of Local Cultural and Language Interaction

    ERIC Educational Resources Information Center

    Manke, Mary Phillips; Keller, Kathryn

    2006-01-01

    Bluff Creek is a prairie town of less than 2000 people. During the period of this study, the families of 20% of the children in its schools were Lao from families who immigrated to the United States in the 1980's, following the Vietnam War. The families of a majority of European-heritage children in the schools were Mennonites whose forebears had…

  3. The economic impact of pig-associated parasitic zoonosis in Northern Lao PDR.

    PubMed

    Choudhury, Adnan Ali Khan; Conlan, James V; Racloz, Vanessa Nadine; Reid, Simon Andrew; Blacksell, Stuart D; Fenwick, Stanley G; Thompson, Andrew R C; Khamlome, Boualam; Vongxay, Khamphouth; Whittaker, Maxine

    2013-03-01

    The parasitic zoonoses human cysticercosis (Taenia solium), taeniasis (other Taenia species) and trichinellosis (Trichinella species) are endemic in the Lao People's Democratic Republic (Lao PDR). This study was designed to quantify the economic burden pig-associated zoonotic disease pose in Lao PDR. In particular, the analysis included estimation of the losses in the pork industry as well as losses due to human illness and lost productivity. A Markov-probability based decision-tree model was chosen to form the basis of the calculations to estimate the economic and public health impacts of taeniasis, trichinellosis and cysticercosis. Two different decision trees were run simultaneously on the model's human cohort. A third decision tree simulated the potential impacts on pig production. The human capital method was used to estimate productivity loss. The results found varied significantly depending on the rate of hospitalisation due to neurocysticerosis. This study is the first systematic estimate of the economic impact of pig-associated zoonotic diseases in Lao PDR that demonstrates the significance of the diseases in that country.

  4. Developing and Implementing a Mobile Conservation Education Unit for Rural Primary School Children in Lao PDR

    ERIC Educational Resources Information Center

    Hansel, Troy; Phimmavong, Somvang; Phengsopha, Kaisone; Phompila, Chitana; Homduangpachan, Khiaosaphan

    2010-01-01

    In this article, the authors examine the implementation and success of a mobile conservation education unit targeting primary schools in central Lao PDR (People's Democratic Republic). The mobile unit conducted 3-hour interactive programs for school children focused on the importance of wildlife and biodiversity around the primary schools in rural…

  5. Dental Screening and Education Among Cambodian, Lowland Lao, and Hmong Refugees in Fresno County, California.

    ERIC Educational Resources Information Center

    Rowe, Donald R.; Jackson, Sidney

    1988-01-01

    Ascertains the dental health needs of the following refugee groups in Fresno County, California: (1) Cambodians; (2) lowland Lao; and (3) Hmong. Discusses successful health marketing and educational strategies aimed at these groups. A Dental Screening program instructed community health specialists, provided dental health education, and performed…

  6. A review of taeniasis and cysticercosis in the Lao People's Democratic Republic.

    PubMed

    Conlan, James; Khounsy, Syseng; Inthavong, Phouth; Fenwick, Stanley; Blacksell, Stuart; Thompson, R C Andrew

    2008-09-01

    Taeniasis and cysticercosis are important but underreported parasitic zoonoses in the Lao People's Democratic Republic (Lao PDR). Reports of human and pig cysticercosis are rather limited and based largely on anecdotal evidence. To date, no structured surveys of disease prevalence or incidence have been reported. However, one unpublished pilot survey of pig cysticercosis in a slaughterhouse in northern Laos estimated prevalence to be 1.7%, without speciation of parasite cysts. Over the past 20 years, nine surveys of intestinal helminthic infection have been conducted; the prevalence of human taeniasis ranged from 0 to 14.0%. The study designs and sample sizes varied greatly, however a high degree of spatial and age variation in taeniasis prevalence was evident. These results are however inconclusive as the species of tapeworm infecting the people was not determined. To further our knowledge of taeniasis and cysticercosis in Lao PDR, structured community-based surveys in high-risk areas are required in combination with the use of sensitive and specific diagnostic tests capable of identifying the pork tapeworm, Taenia solium. This will enable the development and implementation of control measures that are both appropriate and sustainable if T. solium is shown to be a public health threat.

  7. Subtle to severe hepatobiliary morbidity in Opisthorchis viverrini endemic settings in southern Laos.

    PubMed

    Ayé Soukhathammavong, Phonepasong; Rajpho, Virasack; Phongluxa, Khampheng; Vonghachack, Youthanavanh; Hattendorf, Jan; Hongvanthong, Bouasy; Rasaphon, Oroth; Sripa, Banchob; Akkhavong, Kongsap; Hatz, Christoph; Odermatt, Peter

    2015-01-01

    Evidence of severe hepatobiliary morbidity associated with Opisthorchis viverrini liver fluke infection including cholangiocarcinoma (CCA) is scarce in Laos although O. viverrini infection is highly prevalent. We assessed hepatobiliary morbidity using abdominal ultrasonography (US) in O. viverrini adult patients in Saravan province, Southern Laos. A random sample of 431 O. viverrini patients from 10 villages underwent abdominal US. Mild, moderate and markedly advanced periductal fibrosis was diagnosed in 7.0%, 66.5%, and 17.0% of patients, respectively. Normal liver parenchyma was seen in only 9.5% of patients. Presence of gall stones (13.2%), sludge (1.4%), gall wall thickening (1.2%), bile duct dilatation (1.6%), fatty liver (12.0%), kidney stones (8.6%) and cysts (7.9%) were diagnosed in considerable frequencies. In five patients (1.2%) hepatobiliary lesions suggesting CCA were diagnosed. Tumour markers, i.e. Interleukin-6, plasminogen activator inhibitor and carbohydrate antigen 19-9 were within normal range. The number of CCA suspected liver masses and hepatobiliary morbidity diagnosed among clinically asymptomatic adult patients in O. viverrini endemic area presents a major public health concern in Laos. However, definitive diagnosis of Opisthorchis-related severe sequelae including CCA is urgently needed to gauge the burden of this deadly disease in Laos.

  8. Health information systems and disability in the Lao PDR: a qualitative study.

    PubMed

    Durham, Jo; Sychareun, Vanphanom; Rodney, Anna; Gouda, Hebe N; Richards, Nicola; Rampatige, Rasika; Whittaker, Maxine

    2016-10-01

    The Convention on the Rights of Persons with Disabilities provides an opportunity to strengthen disability-related health information. This study analysed the health information system in Lao PDR and sought evidence of interventions to improve disability-related health information. The study was based on a literature review and key informant interviews (N = 17) informed by the Health Metrics Network's Framework and Standards and the Performance of Routine Information System Management framework. The Lao health information system is in an embryonic stage with health data often incomplete, inaccurate and poorly used. Indicators related to disability or functioning are not included, and capacity to diagnose the health condition of disability is limited. No studies of health information interventions were found. As a State Party to the CRPD, the Lao PDR has a legal obligation to collect health-related information on people with disabilities. Given the nascent stage of development of the health information system in the Lao PDR and diagnostic capacity, indicators related to basic functioning and access to services should be integrated into household level surveys. As the health information system further develops, small, incremental changes in the type of disability information and rehabilitation and the way it is collected can be implemented. Copyright © 2015 John Wiley & Sons, Ltd.

  9. Distance Education Policy and Public Awareness in Cambodia, Laos, and Viet Nam

    ERIC Educational Resources Information Center

    Vuth, Doung; Than, Chhuon Chan; Phanousith, Somphone; Phissamay, Phonpasit; Tai, Tran Thi

    2007-01-01

    The current project brings together academic and governmental specialists from Cambodia, Laos, and Viet Nam (CLV), in a collaborative study of the prospects for distance education (DE) in those countries. The study's overall objectives are to: (1) survey and take stock of existing educational scenarios and problems in CLV; (2) document the…

  10. The Diversity and Geographical Structure of Orientia tsutsugamushi Strains from Scrub Typhus Patients in Laos

    PubMed Central

    Phetsouvanh, Rattanaphone; Sonthayanon, Piengchan; Pukrittayakamee, Sasithon; Paris, Daniel H.; Newton, Paul N.; Feil, Edward J.; Day, Nicholas P. J.

    2015-01-01

    Orientia tsutsugamushi is the causative agent of scrub typhus, a disease transmitted by Leptotrombidium mites which is responsible for a severe and under-reported public health burden throughout Southeast Asia. Here we use multilocus sequence typing (MLST) to characterize 74 clinical isolates from three geographic locations in the Lao PDR (Laos), and compare them with isolates described from Udon Thani, northeast Thailand. The data confirm high levels of diversity and recombination within the natural O. tsutsugamushi population, and a rate of mixed infection of ~8%. We compared the relationships and geographical structuring of the strains and populations using allele based approaches (eBURST), phylogenetic approaches, and by calculating F-statistics (FST). These analyses all point towards low levels of population differentiation between isolates from Vientiane and Udon Thani, cities which straddle the Mekong River which defines the Lao/Thai border, but with a very distinct population in Salavan, southern Laos. These data highlight how land use, as well as the movement of hosts and vectors, may impact on the epidemiology of zoonotic infections. PMID:26317624

  11. Azachalcones: a new class of potent polyphenol oxidase inhibitors.

    PubMed

    Radhakrishnan, Sini Karanayil; Shimmon, Ronald Gibrial; Conn, Costa; Baker, Anthony T

    2015-04-15

    A library of potent inhibitors of polyphenol oxidase and their structure activity relationships are described. Azachalcone derivatives were synthesized and tested for their tyrosinase inhibitory activity. Their inhibitory activities on mushroom tyrosinase using l-DOPA as a substrate were investigated. Two compounds that are the reduction congeners of the pyridinyl azachalcones strongly inhibited the enzyme activity and were more potent than the positive control kojic acid.

  12. Superconductivity in a new layered bismuth oxyselenide: LaO(0.5)F(0.5)BiSe₂.

    PubMed

    Krzton-Maziopa, A; Guguchia, Z; Pomjakushina, E; Pomjakushin, V; Khasanov, R; Luetkens, H; Biswas, P K; Amato, A; Keller, H; Conder, K

    2014-05-28

    We report superconductivity at T(c) ≈ 2.6 K in a new layered bismuth oxyselenide LaO(0.5)F(0.5)BiSe2 with the ZrCuSiAs-type structure composed of alternating superconducting BiSe2 and blocking LaO layers. The superconducting properties of LaO(0.5)F(0.5)BiSe2 were investigated by means of dc magnetization, resistivity and muon-spin rotation experiments, revealing the appearance of bulk superconductivity with a rather large superconducting volume fraction of ≈ 70% at 1.8 K.

  13. [Alternative oxidase - never ending story].

    PubMed

    Szal, Bożena; Rychter, Anna M

    2016-01-01

    Investigations of plant cyanide resistant respiration lead to the discovery in mitochondrial respiratory chain of the second terminal oxidase, alternative oxidase (AOX). AOX transfers electrons from reduced ubiquinone to oxygen omitting two coupling places thus lowering energetic efficiency of respiration. The presence of AOX was shown in all plants and also in some fungi, mollusca and protista. In termogenic plants the activity of AOX is connected with heat production. In other organisms AOX activity is important for maintaining metabolic homeostasis (carbon metabolism, cell redox state and energy demand) and ROS homeostasis. In this article structure of plant AOX protein and the regulation on molecular levels was described. Possible role of AOX as stress marker was pointed and the possibility of using AOX in human gene therapy was discussed.

  14. Trematode diversity in the freshwater snail Bithynia siamensis goniomphalos sensu lato from Thailand and Lao PDR.

    PubMed

    Kiatsopit, N; Sithithaworn, P; Kopolrat, K; Namsanor, J; Andrews, R H; Petney, T N

    2016-05-01

    In order to obtain a comprehensive understanding of trematode diversity in Bithynia siamensis goniomphalos sensu lato, the first intermediate host of the liver fluke Opisthorchis viverrini s.l., the prevalence of larval trematode species was investigated in different localities in Thailand and Lao People's Democratic Republic (Lao PDR). In Thailand, snail samples were collected from 29 localities in the nine provinces: Buri Ram, Surin, Chaiya Phum, Maha Sarakham, Khon Kaen, Kalasin, Mukdahan, Sakon Nakhon and Nakhon Phanom. In Lao PDR, snail samples were collected from 21 localities in Vientiane Province and six localities in Savannakhet Province. Snails were identified by standard morphological criteria and then examined for trematode infection using the cercarial shedding method. Twenty different types of cercariae were detected and identified, based on morphological criteria. Virgulate type 1 emerged as the most common cercaria, with an average prevalence of 10.90% (range 0.26-54.22%) in Thailand and 6.58% (range 1.15-89.77%) in Lao PDR. Opisthorchis viverrini s.l. cercariae were the fourth most common in Thailand, with an average prevalence of 1.59% (0.15-6.93), while in Lao PDR their prevalence was 0.96% (0.08-8.37). The high diversity of trematode cercariae observed in this study indicates that B. s. goniomphalos s.l. is highly susceptible to infection with a variety of trematode species. However, the role of non-opisthorchiid trematodes as fish-borne parasites in human health is not fully known and further molecular identification is required.

  15. Status and prospects for livestock production in the Lao People's Democratic Republic.

    PubMed

    Wilson, R Trevor

    2007-08-01

    Some 16 per cent of the Gross Domestic Product of the Lao PDR arises from the livestock sector. Almost all output--live animals and products--is from traditional small scale production and about 90 per cent of all households in the country keep one or more species of livestock. Industrial or large scale production is of very minor importance even for pigs and poultry. Considerable international assistance has been provided for livestock development, initially from the Socialist states that were of the same political persuasion as Lao PDR and more recently from multilateral and bilateral development assistance agencies. In general this assistance has not conferred lasting benefits on the sector in part due to the failure of the Lao Government to provide continuing support commensurate with the sector's contribution to the national economy. Buffalo (1.1 million head in 2004) and cattle (1.3 million head) are the main ruminant species with goats and sheep (140 000 head) occupying a very minor position. Both pigs (1.7 million) and poultry (19.6 million) are major contributors to the household and national economies. Buffalo are now mainly meat producers, their former draught and transport roles having been taken over by mechanical equipment. Cattle, also once used for draught, are almost exclusively producers of beef. Pigs and poultry produce meat and poultry provide eggs. Lao indigenous livestock are mainly kept in low input systems, thus output is also low. Nothing is known of the genetic potential of the indigenous stock which are the victims of poor management, inadequate nutrition and minimal health care. There is strong and rising demand for products of animal origin within the country and in the greater Southeast Asia and East Asia regions. Given suitable and appropriate support the Lao livestock sector would be in a strong position to contribute to supplying this demand.

  16. Lysyl oxidase in cancer research.

    PubMed

    Perryman, Lara; Erler, Janine T

    2014-01-01

    Metastasis is the main reason for cancer-associated deaths and therapies are desperately needed to target the progression of cancer. Lysyl oxidase (LOX) plays a pivotal role in cancer progression, including metastasis, and is therefore is an attractive therapeutic target. In this review we will breakdown the process of cancer progression and the various roles that LOX plays has in the advancement of cancer. We will highlight why LOX is an exciting therapeutic target for the future.

  17. The terminal oxidases of Paracoccus denitrificans.

    PubMed

    de Gier, J W; Lübben, M; Reijnders, W N; Tipker, C A; Slotboom, D J; van Spanning, R J; Stouthamer, A H; van der Oost, J

    1994-07-01

    Three distinct types of terminal oxidases participate in the aerobic respiratory pathways of Paracoccus denitrificans. Two alternative genes encoding subunit I of the aa3-type cytochrome c oxidase have been isolated before, namely ctaDI and ctaDII. Each of these genes can be expressed separately to complement a double mutant (delta ctaDI, delta ctaDII), indicating that they are isoforms of subunit I of the aa3-type oxidase. The genomic locus of a quinol oxidase has been isolated: cyoABC. This protohaem-containing oxidase, called cytochrome bb3, is the only quinol oxidase expressed under the conditions used. In a triple oxidase mutant (delta ctaDI, delta ctaDII, cyoB::KmR) an alternative cytochrome c oxidase has been characterized; this cbb3-type oxidase has been partially purified. Both cytochrome aa3 and cytochrome bb3 are redox-driven proton pumps. The proton-pumping capacity of cytochrome cbb3 has been analysed; arguments for and against the active transport of protons by this novel oxidase complex are discussed.

  18. Sequence analysis of the cbb3 oxidases and an atomic model for the Rhodobacter sphaeroides enzyme.

    PubMed

    Sharma, Vivek; Puustinen, Anne; Wikström, Mårten; Laakkonen, Liisa

    2006-05-09

    The cbb3-type oxidases are members of the heme-copper oxidase superfamily, distant by sequence comparisons, but sharing common functional characteristics. To understand the minimal common properties of the superfamily, and to learn about cbb3-type oxidases specifically, we have analyzed a wide set of heme-copper oxidase sequences and built a homology model of the catalytic subunit of the cbb3 oxidase from Rhodobacter sphaeroides. We conclude that with regard to the active site surroundings, the cbb3 oxidases greatly resemble the structurally known oxidases, while major differences are found in three segments: the additional N-terminal stretch of ca. 60 amino acids, the segment following helix 3 to the end of helix 5, and the C-terminus from helix 11 onward. The conserved core contains the active site tyrosine and also an analogue of the K-channel of proton transfer, but centered on a well-conserved histidine in the lower part of helix 7. Modeling the variant parts of the enzyme suggests that two periplasmic loops (between helices 3 and 4 and between helices 11 and 12) could interact with each other as a part of the active site structure and might have an important role in proton pumping. An analogue of the D-channel is not found, but an alternative channel might form around helix 9. A preliminary packing model of the trimeric enzyme is also presented.

  19. Spinach Thylakoid Polyphenol Oxidase : ISOLATION, ACTIVATION, AND PROPERTIES OF THE NATIVE CHLOROPLAST ENZYME.

    PubMed

    Golbeck, J H; Cammarata, K V

    1981-05-01

    Polyphenol oxidase activity (E.C. 1.14.18.1) has been found in two enzyme species isolated from thylakoid membranes of spinach chloroplasts. The proteins were released from the membrane by sonication and purified >900-fold by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography. The enzymes appear to be the tetramer and monomer of a subunit with a molecular weight of 42,500 as determined by lithium dodecyl sulfate gel electrophoresis. The higher molecular weight enzyme is the predominant form in freshly isolated preparations but on aging or further purification, the amount of lower molecular weight enzyme increases at the expense of the higher.Sonication releases polyphenol oxidase from the membrane largely in the latent state. C(18) fatty acids, especially linolenic acid, are potent activators of the enzymic activity. In the absence of added fatty acids, the isolated enzyme spontaneously, but slowly, activates with time.Purified polyphenol oxidase utilizes o-diphenols as substrates and shows no detectable levels of monophenol or p-diphenol oxidase activities. The K(m) values for 3,4-dihydroxyphenylalanine and O(2) are 6.5 and 0.065 millimolar, respectively. Suitable substrates include chlorogenic acid, catechol, caffeic acid, pyrogallol, and dopamine; however, the enzyme is substrate-inhibited by the last four at concentrations near their K(m) A large seasonal variation in polyphenol oxidase activity may result from a decrease in enzyme content rather than inhibition of the enzyme present.

  20. Expression studies of gibberellin oxidases in developing pumpkin seeds.

    PubMed

    Frisse, Andrea; Pimenta, Maria João; Lange, Theo

    2003-03-01

    Two cDNA clones, 3-ox and 2-ox, have been isolated from developing pumpkin (Cucurbita maxima) embryos that show significant amino acid homology to gibberellin (GA) 3-oxidases and 2-oxidases, respectively. Recombinant fusion protein of clone 3-ox converted GA(12)-aldehyde, GA(12), GA(15), GA(24), GA(25), and GA(9) to GA(14)-aldehyde, GA(14), GA(37), GA(36), GA(13), and GA(4), respectively. Recombinant 2-ox protein oxidized GA(9), GA(4), and GA(1) to GA(51), GA(34), and GA(8), respectively. Previously cloned GA 7-oxidase revealed additional 3beta-hydroxylation activity of GA(12). Transcripts of this gene were identified in endosperm and embryo of the developing seed by quantitative reverse transcriptase-polymerase chain reaction and localized in protoderm, root apical meristem, and quiescent center by in situ hybridization. mRNA of the previously cloned GA 20-oxidase from pumpkin seeds was localized in endosperm and in tissues of protoderm, ground meristem, and cotyledons of the embryo. However, transcripts of the recently cloned GA 20-oxidase from pumpkin seedlings were found all over the embryo, and in tissues of the inner seed coat at the micropylar end. Previously cloned GA 2beta,3beta-hydroxylase mRNA molecules were specifically identified in endosperm tissue. Finally, mRNA molecules of the 3-ox and 2-ox genes were found in the embryo only. 3-ox transcripts were localized in tissues of cotyledons, protoderm, and inner cell layers of the root apical meristem, and 2-ox transcripts were found in all tissues of the embryo except the root tips. These results indicate tissue-specific GA-biosynthetic pathways operating within the developing seed.

  1. Review of the millipede genus Kronopolites Attems, 1914 (Diplopoda, Polydesmida, Paradoxosomatidae), with the description of a new species from Laos

    PubMed Central

    Likhitrakarn, Natdanai; Golovatch, Sergei I.; Panha, Somsak

    2015-01-01

    Abstract The millipede genus Kronopolites currently comprises 11 species, including a new species from northern Laos: Kronopolites lunatus sp. n. The generic diagnosis is updated, a key given to all known species, and their distributions are mapped. PMID:25632247

  2. First record of the family Pseudochactidae Gromov (Chelicerata, Scorpiones) from Laos and new biogeographic evidence of a Pangaean palaeodistribution.

    PubMed

    Lourenço, Wilson R

    2007-10-01

    A new genus and species of scorpion belonging to the recently named family Pseudochactidae is described based on two specimens collected in the Tham Xe Bangfai cave, Province of Khammouan, Laos. This new scorpion represents the second known record of a pseudochactid, and the first from Laos. The possible biogeographic consequences of this scorpion's distribution are discussed, associated with the possible Pangaean origin of pseudochactid scorpions.

  3. Xanthine oxidase inhibition attenuates ischemic-reperfusion lung injury

    SciTech Connect

    Lynch, M.J.; Grum, C.M.; Gallagher, K.P.; Bolling, S.F.; Deeb, G.M.; Morganroth, M.L.

    1988-05-01

    Ischemic-reperfusion lung injury is a factor potentially limiting the usefulness of distant organ procurement for heart-lung transplantation. Toxic oxygen metabolites are considered a major etiologic factor in reperfusion injury. Although oxygen-free radicals may be generated by many mechanisms, we investigated the role of xanthine oxidase in this injury process by using lodoxamide, a xanthine oxidase inhibitor, to inhibit ischemic-reperfusion injury in an isolated rat lung model. Isolated rat lungs were perfused with physiologic salt solution (PSS) osmotically stabilized with Ficoll until circulating blood elements were nondetectable in the pulmonary venous effluent. Lungs were rendered ischemic by interrupting ventilation and perfusion for 2 hr at 37/sup 0/C. After the ischemic interval, the lungs were reperfused with whole blood and lung injury was determined by measuring the accumulation of /sup 125/I-bovine serum albumin in lung parenchyma and alveolar lavage fluid as well as by gravimetric measurements. Lung effluent was collected immediately pre- and postischemia for analysis of uric acid by high-pressure liquid chromatography. Lodoxamide (1 mM) caused significant attenuation of postischemic lung injury. Uric acid levels in the lung effluent confirmed inhibition of xanthine oxidase. Protection from injury was not complete, however, implying that additional mechanisms may contribute to ischemic-reperfusion injury in the lung.

  4. Effect of polymerization on antioxidant and xanthine oxidase inhibitory potential of sea buckthorn (H. rhamnoides) proanthocyanidins.

    PubMed

    Arimboor, Ranjith; Arumughan, C

    2012-10-01

    Inhibitory potential of sea buckthorn (Hippophae rhamnoides L) seed proanthocyanidins against oxidative stress and xanthine oxidase activity was evaluated. Composition of antioxidant proanthocyanidins was profiled by analyzing the cleavage products obtained by the acid catalyzed hydrolysis in the presence of phloroglucinol. Catechin, epicatechin, gallocatechin, and epigallocatechin were found as the extension and terminal subunits of proanthocyanidins with an average degree of polymerization (ADP) of 14.7. Seed proanthocyanidins showed considerably high antioxidant and xanthine oxidase inhibitory potentials. Antioxidant and xanthine oxidase inhibitory capacity evaluation of proanthocyanidin fractions with varying ADP showed that proanthocyanidins with lower molecular size were more effective as superoxide anion (ADP ≤ 4.2) and hydroxyl radical (ADP ≤ 5.9) scavengers and xanthine oxidase (ADP ≤ 3.1) inhibitors. ADP of the studied proanthocyanidin fractions did not show significant influence on their DPPH and ABTS radical scavenging and ferric reduction capacities.

  5. Monoamine Oxidase Inhibitors: Clinical Review

    PubMed Central

    Remick, Ronald A.; Froese, Colleen

    1990-01-01

    Monoamine oxidase inhibitors (MAOIs) are effective antidepressant agents. They are increasingly and effectively used in a number of other psychiatric and non-psychiatric medical syndromes. Their potential for serious toxicity (i.e., hypertensive reaction) is far less than original reports suggest, and newer reversible substrate-specific MAOIs may offer even less toxicity. The author reviews the pharmacology, mechanism of action, clinical indications, and dosing strategies of MAOIs. The common MAOI side-effects (hypotension, weight gain, sexual dysfunction, insomnia, daytime sedation, myoclonus, and hypertensive episodes) are described and management techniques suggested. Recent clinical developments involving MAOIs are outlined. PMID:21233984

  6. Human neurocysticercosis case and an endemic focus of Taenia solium in Lao PDR.

    PubMed

    Jeon, Hyeong-Kyu; Yong, Tai-Soon; Sohn, Woon-Mok; Chai, Jong-Yil; Min, Duk-Young; Rim, Han-Jong; Insisiengmay, Bounnaloth; Eom, Keeseon S

    2013-10-01

    A male patient with neurocysticercosis was identified in Montai Village, Xay District, Oudomxay Province, Lao PDR in February 2004. He had a history of diagnosis for neurocysticercosis by a CT scan in Thailand after an onset of epileptic seizure in 1993. A pig in the same district was found to contain Taenia solium metacestodes (=cysticerci); the slaughtered pig body contained more than 2,000 cysticerci. In addition to morphological identification, molecular identification was also performed on the cysticerci by DNA sequencing analysis of the mitochondrial cox1 gene; they were confirmed as T. solium metacestodes. The patient is regarded as an indigenous case of neurocysticercosis infected in an endemic focus of T. solium taeniasis/cysticercosis in Oudomxay Province, Lao PDR.

  7. Human Neurocysticercosis Case and an Endemic Focus of Taenia solium in Lao PDR

    PubMed Central

    Jeon, Hyeong-Kyu; Yong, Tai-Soon; Sohn, Woon-Mok; Chai, Jong-Yil; Min, Duk-Young; Rim, Han-Jong; Insisiengmay, Bounnaloth

    2013-01-01

    A male patient with neurocysticercosis was identified in Montai Village, Xay District, Oudomxay Province, Lao PDR in February 2004. He had a history of diagnosis for neurocysticercosis by a CT scan in Thailand after an onset of epileptic seizure in 1993. A pig in the same district was found to contain Taenia solium metacestodes (=cysticerci); the slaughtered pig body contained more than 2,000 cysticerci. In addition to morphological identification, molecular identification was also performed on the cysticerci by DNA sequencing analysis of the mitochondrial cox1 gene; they were confirmed as T. solium metacestodes. The patient is regarded as an indigenous case of neurocysticercosis infected in an endemic focus of T. solium taeniasis/cysticercosis in Oudomxay Province, Lao PDR. PMID:24327790

  8. Mentoring Cambodian and Lao health professionals in tobacco control leadership and research skills

    PubMed Central

    Ferry, L Hyder; Job, J; Knutsen, S; Montgomery, S; Petersen, F; Rudatsikira, E; Singh, P

    2006-01-01

    Design The aim of the programme was to ultimately affect public health practice and policy in the Kingdom of Cambodia and Lao People's Democratic Republic (Lao PDR) by training key health professionals to conduct tobacco control research. Setting Encouraged by the World Health Organization's Framework Convention on Tobacco Control, a global partnership formed to build effective leadership to develop and guide national tobacco control agendas. The partners were the Ministries of Health (Cambodia and Lao PDR), non‐government organisations (Adventist Development and Relief Agency in Cambodia and Laos) and an academic institution (Loma Linda University, Loma Linda, California, USA). Subjects 16 health professionals, 10 from Cambodia and 6 from Lao PDR, were selected by local advisory committees to enter a two‐year, intensive tobacco research graduate certificate and research training programme. Intervention We developed a “Global Tobacco Control Methods” (GTCM) 28 unit certificate programme that was offered in five sessions from September 2003 to September 2005 at the National Institute of Public Health, Phnom Penh, Cambodia. As part of their coursework, the 16 trainees actively participated in the development and implementation of two research projects. In the first project, “Healthy Doc Healthy Patient” (HDHP), trainees adapted an existing, self‐administered questionnaire designed to assess health practices and beliefs of medical students in Cambodia and Lao PDR. The second project involved the design of a national prevalence of tobacco use and health beliefs study in Cambodia using a multi‐stage, cluster sample method. Trainees were sponsored to attend and present at international tobacco control conferences to enhance their awareness of the tobacco epidemic. Results As of September 2005, 14 trainees (8 from Cambodia and 6 from Lao PDR) completed the courses in the GTCM certificate programme. The HDHP study sampled four medical school classes (years

  9. Skin Test for Paragonimiasis among Schoolchildren and Villagers in Namback District, Luangprabang Province, Lao PDR

    PubMed Central

    Song, Hyun-Ouk; Rim, Han-Jong; Youthanavanh, Vonghachack; Daluny, Bouakhasith; Sengdara, Vongsouvan; Virasack, Banouvong; Bounlay, Phommasak

    2008-01-01

    As a part of a broader effort to determine the status of Paragonimus species infection in Lao PDR, an epidemiological survey was conducted on villagers and schoolchildren in Namback District between 2003 and 2005. Among 308 villagers and 633 primary and secondary schoolchildren, 156 villagers and 92 children evidenced a positive reaction on a Paragonimus skin test. Only 4 schoolchildren out of 128 skin test-positive cases had Paragonimus sp. eggs in their sputum, all of which was collected on 1 day. Several types of crabs, which were identified as the second intermediate host of the Paragonimus species, were collected from markets and streams in a paragonimiasis endemic area for the inspection of metacercariae. Among the examined crabs, only "rock crabs" (Indochinamon ou) harbored Paragonimus sp. metacercariae, and it is speculated that the life cycle of Paragonimus sp. was maintained via rock crabs in Namback District, Lao PDR. PMID:18830059

  10. Research into the functional components and antioxidant activities of North China rice wine (Ji Mo Lao Jiu)

    PubMed Central

    He, Shuai; Mao, Xiangzhao; Liu, Pei; Lin, Hong; Du, Zuyuan; Lv, Ning; Han, Jichen; Qiu, Cuifang

    2013-01-01

    Over the last decade, considerable experimental evidence has supported the view that grape wine and South China rice wine are rich in diverse nutrients and have powerful antioxidant activity. However, little research has been carried out for North China rice wine, of which Ji Mo Lao Jiu (JMLJ) is the outstanding representative. In this study, the functional components and antioxidant activity of JMLJ were investigated. Twenty-eight free amino acids were found in JMLJ, much more than that previously reported in other Chinese rice wines (16–21). Functional oligosaccharides (5290.222 mg/L), total phenols (722.431 ± 10.970 mg/L), and mineral elements (9) were rich in JMLJ. When compared with synthetic antioxidants, such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), JMLJ showed effective 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging and reducing capacity. The results of this study lay the foundation for promoting the utilization of JMLJ and the development of North China rice wine in the food industry. PMID:24804035

  11. The United States Air Force in Southeast Asia: Interdiction in Southern Laos, 1960-1968

    DTIC Science & Technology

    1993-01-01

    vehicles, weapons, and motorable roads, MACV ordered 2d Air Division to make a special STEEL TIGER strike. This was executed by B-57s on November 5...contained motorable infiltration routes, command centers, and training and supply bases similar to those in Laos. The State Department weighed the...by [the] Ambassador and RLG authority.” Besides RLAF-validated targets and “ motorized vehicles,” the targets included automatic weapons and

  12. Project CHECO Southeast Asia Report. Air War In Northern Laos, 1 April - 30 November 1971

    DTIC Science & Technology

    1973-06-22

    11 Waterpump 11 mechanics from Det 1, 56 SOW, while major maintenance was 92 performed by Air America at Udorn RTAFB. Although small in number, the...also involved in support for Laos in a number of other ways. The Waterpump /MAP program has already been mentioned (page 48). Medevac and air rescue...targets within 200 meters of a motorable road, they had adopted the simple expedient of stacking supplies in the open just beyond this limit. The

  13. The United States Air Force in Southeast Asia: The War in Northern Laos, 1954-1973

    DTIC Science & Technology

    1993-01-01

    economic or military benefits. At the same time, the French wished to restrain Thai influence along the Mekong, an influence the French felt would...resentment of the mountain people was later exploited by the Viet Minh following World War Et.13 (£) Economically , the French did little for Laos. There...Laotian people that France had not abandoned them. More important , .they were to be the nucleus for reestablishing French rule following Japan’s

  14. Asiagomphus reinhardti sp. nov. (Odonata, Gomphidae) from eastern Cambodia and southern Laos.

    PubMed

    Kosterin, Oleg E; Yokoi, Naoto

    2016-04-11

    Asiagomphus reinhardti sp. nov. is described by two males from Annamense Mountains in eastern Cambodia (holotype: Cambodia, Mondulkiri Province, the left tributary of the main river downstream from Buu Sraa Waterfall, 12°34'01-19'' N 107°24'50''-25'03'' E, ca 450 m a.s.l., 15 vi 2014, RMNH) and southern Laos. The species is characterised by a large caudal lobe on S10 in males and a blunt medial lateroventral projection at cercus.

  15. District health programmes and health-sector reform: case study in the Lao People's Democratic Republic.

    PubMed Central

    Perks, Carol; Toole, Michael J.; Phouthonsy, Khamla

    2006-01-01

    The Lao People's Democratic Republic (Lao PDR) is classified by the World Bank as a low-income country under stress. Development partners have sought to utilize effective aid instruments to help countries classified in this way achieve the Millennium Development Goals; these aid instruments include sector-wide approaches (SWAps) that support decentralized district health systems and seek to avoid fragmentation and duplication. In Asia and the Pacific, only Bangladesh, Papua New Guinea and the Solomon Islands have adopted SWAps. Since 1991, a comprehensive primary health care programme in the remote Sayaboury Province of Lao PDR has focused on strengthening district health management, improving access to health facilities and responding to the most common causes of mortality and morbidity among women and children. Between 1996 and 2003, health-facility utilization tripled, and the proportion of households that have access to a facility increased to 92% compared with only 61% nationally. By 2003, infant and child mortality rates were less than one-third of the national rates. The maternal mortality ratio decreased by 50% despite comprehensive emergency obstetric care not being available in most district hospitals. These trends were achieved with an investment of approximately 4 million US dollars over 12 years (equivalent to US 1.00 US dollars per person per year). However, this project did not overcome weaknesses in some national disease-control programmes, especially the expanded programme on immunization, that require strong central management. In Lao PDR, which is not yet committed to using SWAps, tools developed in Sayaboury could help other district health offices assume greater planning responsibilities in the recently decentralized system. Development partners should balance their support for centrally managed disease-specific programmes with assistance to horizontally integrated primary health care at the district level. PMID:16501731

  16. Mitochondrial cytochrome c oxidase deficiency.

    PubMed

    Rak, Malgorzata; Bénit, Paule; Chrétien, Dominique; Bouchereau, Juliette; Schiff, Manuel; El-Khoury, Riyad; Tzagoloff, Alexander; Rustin, Pierre

    2016-03-01

    As with other mitochondrial respiratory chain components, marked clinical and genetic heterogeneity is observed in patients with a cytochrome c oxidase deficiency. This constitutes a considerable diagnostic challenge and raises a number of puzzling questions. So far, pathological mutations have been reported in more than 30 genes, in both mitochondrial and nuclear DNA, affecting either structural subunits of the enzyme or proteins involved in its biogenesis. In this review, we discuss the possible causes of the discrepancy between the spectacular advances made in the identification of the molecular bases of cytochrome oxidase deficiency and the lack of any efficient treatment in diseases resulting from such deficiencies. This brings back many unsolved questions related to the frequent delay of clinical manifestation, variable course and severity, and tissue-involvement often associated with these diseases. In this context, we stress the importance of studying different models of these diseases, but also discuss the limitations encountered in most available disease models. In the future, with the possible exception of replacement therapy using genes, cells or organs, a better understanding of underlying mechanism(s) of these mitochondrial diseases is presumably required to develop efficient therapy.

  17. Immunological comparison of sulfite oxidase

    SciTech Connect

    Pollock, V.; Barber, M.J. )

    1991-03-11

    Polyclonal antibodies (rabbit), elicited against FPLC-purified chicken and rat liver sulfite oxidase (SO), have been examined for inhibition and binding to purified chicken (C), rat (R), bovine (B), alligator (A) and shark (S) liver enzymes. Anti-CSO IgG cross-reacted with all five enzymes, with varying affinities, in the order CSO=ASO{gt}RSO{gt}BSO{gt}SSO. Anti-ROS IgG also cross-reacted with all five enzymes in the order RSO{gt}CSO=ASO{gt}BSO{gt}SSO. Anti-CSO IgG inhibited sulfite:cyt. c reductase (S:CR), sulfite:ferricyanide reductase (S:FR) and sulfite:dichlorophenolindophenol reductase (S:DR) activities of CSO to different extents (S:CR{gt}S:FR=S:DR). Similar differential inhibition was found for anti-ROS IgG and RSO S:CR, S:FR and S:DR activities. Anti-CSO IgG inhibited S:CR activities in the order CSO=ASO{much gt}SSO{gt}BSO. RSO was uninhibited. For anti-RSO IgG the inhibition order was RSO{gt}SSO{gt}BSO{gt}ASO. CSO was uninhibited. Anti-CSO and RSO IgGs partially inhibited Chlorella nitrate reductase (NR). Minor cross-reactivity was found for xanthine oxidase. Common antigenic determinants for all five SO's and NR are indicated.

  18. Mitochondrial Cytochrome c Oxidase Deficiency

    PubMed Central

    Rak, Malgorzata; Bénit, Paule; Chrétien, Dominique; Bouchereau, Juliette; Schiff, Manuel; El-Khoury, Riyad; Tzagoloff, Alexander; Rustin, Pierre

    2016-01-01

    As with other mitochondrial respiratory chain components, marked clinical and genetic heterogeneity is observed in patients with a cytochrome c oxidase deficiency. This constitutes a considerable diagnostic challenge and raises a number of puzzling questions. So far, pathological mutations have been reported in more than 30 genes, in both mitochondrial and nuclear DNA, affecting either structural subunits of the enzyme or proteins involved in its biogenesis. In this review, we discuss the possible causes of the discrepancy between the spectacular advances made in the identification of the molecular bases of cytochrome oxidase deficiency and the lack of any efficient treatment in diseases resulting from such deficiencies. This brings back many unsolved questions related to the frequent delay of clinical manifestation, variable course and severity, and tissue-involvement often associated with these diseases. In this context, we stress the importance to study different models of these diseases, but also discuss the limitations encountered in most available disease models. In the future, with the possible exception of replacement therapy using genes, cells or organs, a better understanding of underlying mechanism(s) of these mitochondrial diseases is presumably required to develop efficient therapy. PMID:26846578

  19. Seroprevalence of Q fever, Brucellosis, and Bluetongue in Selected Provinces in Lao People's Democratic Republic

    PubMed Central

    Douangngeun, Bounlom; Theppangna, Watthana; Soukvilay, Vilayvahn; Senaphanh, Chanthana; Phithacthep, Kamphok; Phomhaksa, Souk; Yingst, Samuel; Lombardini, Eric; Hansson, Eric; Selleck, Paul W.; Blacksell, Stuart D.

    2016-01-01

    This study has determined the proportional seropositivity of two zoonotic diseases, Q fever and brucellosis, and bluetongue virus (BTV) which is nonzoonotic, in five provinces of Lao People's Democratic Republic (PDR) (Loungphabang, Luangnumtha, Xayaboury, Xiengkhouang, and Champasak, and Vientiane Province and Vientiane capital). A total of 1,089 samples from buffalo, cattle, pigs, and goats were tested, with seropositivity of BTV (96.7%), Q fever (1.2%), and brucellosis (0.3%). The results of this survey indicated that Q fever seropositivity is not widely distributed in Lao PDR; however, Xayaboury Province had a cluster of seropositive cattle in seven villages in four districts (Botan, Kenthao, Paklaiy, and Phiang) that share a border with Thailand. Further studies are required to determine if Xayaboury Province is indeed an epidemiological hot spot of Q fever activity. There is an urgent need to determine the levels of economic loss and human health-related issues caused by Q fever, brucellosis, and BTV in Lao PDR. PMID:27430548

  20. ENVIRONMENTAL EXPOSURES, LUNG FUNCTION, AND RESPIRATORY HEALTH IN RURAL LAO PDR

    PubMed Central

    Lopez, Jaime R; Somsamouth, Khamphithoune; Mounivong, Boualoy; Sinclair, Ryan; Soret, Sam; Knutsen, Synnove; Singh, Pramil N

    2014-01-01

    Although the individual contributions of smoked tobacco and indoor air pollution have been identified, there are very few studies that have characterized and measured the effects of inhaled particles from a wide range of personal, household, and community practices common in rural Asia. The objective of our study was to examine the association between environmental inhaled exposures and lung function among rural males of Lao PDR. In a sample of 92 males from rural Lao PDR, study subjects completed a survey on household exposures, a physical exam, and the following measures of lung function: FEV1, FVC, and the ratio of FEV1/FVC. Our findings were as follows: a) > 80% of the subjects were exposed to indoor cooking fires (wood fuel), animal handling, dust and dirt; b) 57.6% of subjects were in the impaired range (FEV1/FVC < 0.7); and c) animal handling was negatively associated (p<0.03) with FEV1 and FVC. Among males in rural Lao PDR, we found a high prevalence of chronic exposure to inhaled particles (animal handling, dust/dirt, smoke) and a high prevalence of impaired lung function. Findings from this pilot study indicate that associations between exposure to multiple sources of particulate matter common in rural areas and lung function need further investigation. PMID:24964671

  1. [A french-speaking institute for tropical medicine in Asia: the IFMT in Vientiane, Lao PDR].

    PubMed

    Strobel, M

    2006-02-01

    Since the year-2000, a French-speaking Institute for Tropical Medicine (French acronym, IFMT) has been operating in Lao PDR through funding provided by the Agence Universitaire de la Francophonie. The IFMT is a postgraduate teaching centre dedicated to improving skills of health care professionals in clinical sciences, epidemiology, public health and management as well as to research and health care intervention. These activities are conducted in the capital as well as provinces and districts throughout Laos with special focus on priority health issues facing developing countries in tropical regions. The IFMT organizes a 4-semester international course taught in French to medical doctors from Southeast Asia, mainly Laos, Cambodia, Vietnam and Southern China, but also from other countries. To date, a total of 72 students have graduated from the IFMT. In 2005 the Institute delivers a master degree. This article describes the course objectives and some features of the curriculum. It also presents a general overview of health, teaching, and research facilities in Southeast Asia as well as of the major challenges now confronting the region.

  2. Environmental exposures, lung function, and respiratory health in rural Lao PDR.

    PubMed

    Lopez, Jaime R; Somsamouth, Khamphithoune; Mounivong, Boualoy; Sinclair, Ryan; Soret, Sam; Knutsen, Synnove; Singh, Pramil N

    2014-01-01

    Although the individual contributions of smoked tobacco and indoor air pollution have been identified, there are very few studies that have characterized and measured the effects of inhaled particles from a wide range of personal, household, and community practices common in rural Asia. The objective of our study was to examine the association between environmental inhaled exposures and lung function among rural males of Lao PDR. In a sample of 92 males from rural Lao PDR, study subjects completed a survey on household exposures, a physical exam, and the following measures of lung function: FEV1, FVC, and the ratio of FEV1/FVC. Our findings were as follows: a) > 80% of the subjects were exposed to indoor cooking fires (wood fuel), animal handling, dust and dirt; b) 57.6% of subjects were in the impaired range (FEV1/FVC < 0.7); and c) animal handling was negatively associated (p < 0.03) with FEV1 and FVC. Among males in rural Lao PDR, we found a high prevalence of chronic exposure to inhaled particles (animal handling, dust/dirt, smoke) and a high prevalence of impaired lung function. Findings from this pilot study indicate that associations between exposure to multiple sources of particulate matter common in rural areas and lung function need further investigation.

  3. "The perfect business": human trafficking and Lao-Thai cross-border migration.

    PubMed

    Molland, Sverre

    2010-01-01

    Over the past few years some governments and development organizations have increasingly articulated cross-border mobility as "trafficking in persons". The notion of a market where traffickers prey on the "supply" of migrants that flows across international borders to meet the "demand" for labour has become a central trope among anti-trafficking development organizations. This article problematizes such economism by drawing attention to the oscillating cross-border migration of Lao sex workers within a border zone between Laos and Thailand. It illuminates the incongruity between the recruitment of women into the sex industry along the Lao-Thai border and the market models that are employed by the anti-trafficking sector. It discusses the ways in which these cross-border markets are conceived in a context where aid programming is taking on an increasingly important role in the politics of borders. The author concludes that allusions to ideal forms of knowledge (in the guise of classic economic theory) and an emphasis on borders become necessary for anti-trafficking programmes in order to make their object of intervention legible as well as providing post-hoc rationalizations for their continuing operation.

  4. Subtype identification of human Blastocystis spp. isolated from Lao People's Democratic Republic.

    PubMed

    Sanpool, Oranuch; Laymanivong, Sakhone; Thanchomnang, Tongjit; Rodpai, Rutchanee; Sadaow, Lakkhana; Phosuk, Issarapong; Maleewong, Wanchai; Intapan, Pewpan M

    2017-04-01

    Blastocystis sp. is the most common protist found in the intestinal tract of humans and animals. Blastocystis subtypes (STs) are classified based on the molecular phylogeny of the small subunit rRNA gene (SSU rDNA). At least 17 Blastocystis STs have been reported and, of these, STs 1-9 have been found in humans. This study revealed the presence of human Blastocystis STs in Lao People's Democratic Republic (Lao PDR). Fecal samples were collected from apparently healthy people from the central province of Khammouane and the southern province of Champasak. Fresh fecal samples, found to be positive for Blastocystis using microscopy, were individually cultured in Jones' medium and each sample was used for the amplification and sequencing of a fragment of SSU rDNA. BLAST searches and phylogenetic analysis confirmed the distribution of four Blastocystis STs: ST1 (64%), ST2 (8%), ST3 (24%) and ST7 (4%). This is the first report to provide molecular data revealing the prevalence of Blastocystis STs in apparently healthy people from Lao PDR.

  5. Rapid deactivation of NADPH oxidase in neutrophils: continuous replacement by newly activated enzyme sustains the respiratory burst.

    PubMed

    Akard, L P; English, D; Gabig, T G

    1988-07-01

    The cell-free system for activation of the neutrophil NADPH oxidase allowed us to examine activation of the oxidase in the absence of its NADPH-dependent turnover. The covalent sulfhydryl-modifying reagent N-ethylmaleimide completely inhibited the activation step (Ki = 40 mumol/L) in the cell-free system but had no effect on turnover of the preactivated particulate NADPH oxidase (up to 1 mmol/L). When N-ethylmaleimide was added to intact neutrophils during the period of maximal O2 generation in response to stimuli that activate the respiratory burst (phorbol myristate acetate, f-Met-Leu-Phe, opsonized zymosan, arachidonic acid), O2- generation ceased within seconds. Study of components of the cell-free activation system indicated that the cytosolic cofactor was irreversibly inhibited by N-ethylmaleimide whereas the N-ethylmaleimide-treated, membrane-associated oxidase could be activated by arachidonate and control cytosolic cofactor. Likewise, the cell-free system prepared from intact neutrophils that had been briefly exposed to N-ethylmaleimide and then washed reflected the effects of N-ethylmaleimide on the isolated cell-free components: cytosolic cofactor activity was absent, but the membrane oxidase remained fully activatable. Thus inhibition of oxidase activation by N-ethylamaleimide unmasked a rapid deactivation step that was operative in intact neutrophils but not in isolated particulate NADPH oxidase preparations. The demonstrated specificity of N-ethylmaleimide for oxidase activation and lack of effect on turnover of the NADPH oxidase suggested that sustained O2- generation by intact neutrophils was a result of continued replenishment of a small pool of active oxidase. The existence of an inactive pool of NADPH oxidase molecules in particulate preparations from stimulated neutrophils was supported more directly by activating these preparations again in the cell-free system.

  6. Respiration of bloodstream forms of the parasite Trypanosoma brucei brucei is dependent on a plant-like alternative oxidase.

    PubMed

    Clarkson, A B; Bienen, E J; Pollakis, G; Grady, R W

    1989-10-25

    CoQ links the sn-glycerol-3-phosphate dehydrogenase and oxidase components of the cyanide-insensitive, non-cytochrome-mediated respiratory system of bloodstream African trypanosomes. In this and other characteristics, their respiratory system is similar to the alternative oxidase of plants. The parasites contain 206 ng of CoQ9 mg protein-1 which co-sediments with respiratory activity. The redox state of this CoQ responds in a manner consistent with respiratory function: 60% being in the reduced form when substrate is available and the oxidase is blocked; 13% being in the reduced form when the oxidase is functioning and there is no substrate. The addition of CoQ to aceton-extracted cells stimulates salicylhydroxamic acid-sensitive respiration by 56%. After inhibition of respiration by digitonin-mediated dispersal of the electron transport components, liposomes restore 40% of respiratory activity while liposomes containing CoQ restore 66% of this activity. A less hydrophobic analogue, reduced decyl CoQ, serves as a direct substrate for the trypanosome oxidase supporting full salicylhydroxamic acid-sensitive respiration. After digitonin disruption of electron transport, the nonreduced form of this synthetic substrate can reestablish the chain by accepting electrons from dispersed sn-glycerol-3-phosphate dehydrogenase and transferring them to the dispersed oxidase. Similarities between the alternative oxidase of plants and the oxidase of the trypanosome respiratory system include: mitochondrial location, lack of oxidative phosphorylation, linkage of a dehydrogenase and an oxidase by CoQ, lack of sensitivity to a range of mitochondrial inhibitors, and sensitivity to a spectrum of inhibitors which selectively block transfer of electrons from reduced CoQ to the terminal oxidase but do not block electron transfer to the cytochrome bc1 complex of the mammalian cytochrome chain.

  7. Excess boron reduces polyphenol oxidase activities in embryo and endosperm of maize seed during germination.

    PubMed

    Olçer, Hillya; Kocaçaliskan, Ismail

    2007-01-01

    The effects of increasing concentrations of boron (0, 0.1, 1, 10 and 20 mM) as boric acid on the rate of germination and polyphenol oxidase activities in embryo and endosperm tissues of maize seeds (Zea mays L. cv. Arifiye) were studied. The germination percentage of maize seeds was not affected by boron concentrations up to 10 mM, and decreased by 20 mM. Distilled water and lower boron concentrations (0.1 and 1 mM) increased polyphenol oxidase activities at the beginning of germination up to 12 h whereas its excess levels (10 and 20 mM) decreased polyphenol oxidase activities in embryos and endosperm during germination. Polyphenol oxidase activities with o-diphenolic substrates (caffeic acid, catechol and dopa) were found to be higher than with a monophenolic substrat (tyrosine) in both embryos and endosperms. Further, caffeic acid oxidizing polyphenol oxidase was found to show more activity in embryos of the seeds germinating in distilled water when compared to other substrates.

  8. Spinach thylakoid polyphenol oxidase isolation, activation, and properties of the native chloroplast enzyme

    SciTech Connect

    Golbeck, J.H.; Cammarata, K.V.

    1981-05-01

    Polyphenol oxidase activity (E.C. 1.14,18.1) has been found in two enzyme species isolated from thylakoid membranes of spinach chloroplasts. The proteins were released from the membrane by sonication and purified >900-fold by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography. The enzymes appear to be the tetramer and monomer of a subunit with a molecular weight of 42,500 as determined by lithium dodecyl sulfate gel electrophoresis. Sonication releases polyphenol oxidase from the membrane largely in the latent state. In the absence of added fatty acids, the isolated enzyme spontaneously, but slowly, activates with time. Purified polyphenol oxidase utilizes o-diphenols as substrates and shows no detectable levels of monophenol or p-diphenol oxidase activities. Suitable substrates include chlorogenic acid, catechol, caffeic acid, pyrogallol, and dopamine; however, the enzyme is substrate-inhibited by the last four at concentrations near their K/sub m/. A large seasonal variation in polyphenol oxidase activity may result from a decrease in enzyme content rather than inhibition of the enzyme present.

  9. Phenol oxidase activity in secondary transformed peat-moorsh soils

    NASA Astrophysics Data System (ADS)

    Styła, K.; Szajdak, L.

    2009-04-01

    The chemical composition of peat depends on the geobotanical conditions of its formation and on the depth of sampling. The evolution of hydrogenic peat soils is closely related to the genesis of peat and to the changes in water conditions. Due to a number of factors including oscillation of ground water level, different redox potential, changes of aerobic conditions, different plant communities, and root exudes, and products of the degradation of plant remains, peat-moorsh soils may undergo a process of secondary transformation conditions (Sokolowska et al. 2005; Szajdak et al. 2007). Phenol oxidase is one of the few enzymes able to degrade recalcitrant phenolic materials as lignin (Freeman et al. 2004). Phenol oxidase enzymes catalyze polyphenol oxidation in the presence of oxygen (O2) by removing phenolic hydrogen or hydrogenes to from radicals or quinines. These products undergo nucleophilic addition reactions in the presence or absence of free - NH2 group with the eventual production of humic acid-like polymers. The presence of phenol oxidase in soil environments is important in the formation of humic substances a desirable process because the carbon is stored in a stable form (Matocha et al. 2004). The investigations were carried out on the transect of peatland 4.5 km long, located in the Agroecological Landscape Park host D. Chlapowski in Turew (40 km South-West of Poznań, West Polish Lowland). The sites of investigation were located along Wyskoć ditch. The following material was taken from four chosen sites marked as Zbechy, Bridge, Shelterbelt and Hirudo in two layers: cartel (0-50cm) and cattle (50-100cm). The object of this study was to characterize the biochemical properties by the determination of the phenol oxidize activity in two layers of the four different peat-moors soils used as meadow. The phenol oxidase activity was determined spectrophotometrically by measuring quinone formation at λmax=525 nm with catechol as substrate by method of Perucci

  10. The function of ascorbate oxidase in tobacco.

    PubMed

    Pignocchi, Cristina; Fletcher, John M; Wilkinson, Joy E; Barnes, Jeremy D; Foyer, Christine H

    2003-07-01

    The function of the apoplastic enzyme ascorbate oxidase (AO) was investigated in tobacco (Nicotiana tabacum). The abundance of AO mRNA was up-regulated by light. Cytosolic ascorbate peroxidase (APX1) transcripts were also highest in the light. In contrast, L-galactono-gamma-lactone dehydrogenase, stromal APX, and thylakoid APX transcripts remained constant over the day/night cycle. Salicylic acid inhibited growth, increased expression of the pathogenesis-related protein (PR) 1a, and decreased AO transcript abundance. In contrast, the application of auxin enhanced growth and increased AO and PR 1a gene expression. Therefore, AO transcript abundance varied in a manner similar to hormone-mediated changes in plant growth. To study the effects of modified AO expression on growth, transformed tobacco plants expressing AO in the sense and antisense orientations were generated. The resultant large changes in apoplastic AO activity in the transformed tobacco plants had little effect on whole leaf ascorbate (AA) content, but they had dramatic effects on apoplastic AA levels. Enhanced AO activity oxidized the apoplastic AA pool, whereas decreased AO activity increased the amount of AA compared with dehydroascorbate. A relationship was observed between AO activity and plant height and biomass. Native AO transcript levels were no longer subject to light/dark regulation in AO sense and antisense plants. Taken together, these data show that there is an interaction between hormone, redox, and light signals at the level of the apoplast via modulation of ion of AA content.

  11. Dietary inhibitors of monoamine oxidase A.

    PubMed

    Dixon Clarke, Sarah E; Ramsay, Rona R

    2011-07-01

    Inhibition of monoamine oxidase is one way to treat depression and anxiety. The information now available on the pharmacokinetics of flavonoids and of the components of tobacco prompted an exploration of whether a healthy diet (with or without smoking) provides active compounds in amounts sufficient to partially inhibit monoamine oxidase. A literature search was used to identify dietary monoamine oxidase inhibitors, the levels of these compounds in foods, the pharmacokinetics of the absorption and distribution, and tissue levels observed. An estimated daily intake and the expected tissue concentrations were compared with the measured efficacies of the compounds as inhibitors of monoamine oxidases. Norharman, harman and quercetin dietary presence, pharmacokinetics, and tissue levels were consistent with significant levels reaching neuronal monoamine oxidase from the diet or smoking; 1,2,3,4-tetrahydroisoquinoline, eugenol, 1-piperoylpiperidine, and coumarin were not. Quercetin was equipotent with norharman as a monoamine oxidase A inhibitor and its metabolite, isorhamnetin, also inhibits. Total quercetin was the highest of the compounds in the sample diet. Although bioavailability was variable depending on the source, a healthy diet contains amounts of quercetin that might give sufficient amounts in brain to induce, by monoamine oxidase A inhibition, a small decrease in neurotransmitter breakdown.

  12. Crystal Structures of Intermediates in the Nitroalkane Oxidase Reaction†

    PubMed Central

    Héroux, Annie; Bozinovski, Dragana M.; Valley, Michael P.; Fitzpatrick, Paul F.; Orville, Allen M.

    2009-01-01

    The flavoenzyme nitroalkane oxidase is a member of the acyl-CoA dehydrogenase superfamily. Nitroalkane oxidase catalyzes the oxidation of neutral nitroalkanes to nitrite and the corresponding aldehydes or ketones. Crystal structures to 2.2 Å resolution or better are described of enzyme complexes with bound substrates and of a trapped substrate-flavin adduct. The D402N enzyme has no detectable activity with neutral nitroalkanes (Valley, M. P., and Fitzpatrick, P. F. (2003) J. Am. Chem. Soc. 23, 8738–8739). The structure of the D402N enzyme crystallized in the presence of 1-nitrohexane or 1-nitrooctane shows the presence of the substrate in the binding site. The aliphatic chain of the substrate extends into a tunnel leading to the enzyme surface. The oxygens of the substrate nitro group interact both with amino acid residues and with the 2’-hydroxyl of the FAD. When nitroalkane oxidase oxidizes nitroalkanes in the presence of cyanide, an electrophilic flavin imine intermediate can be trapped (Valley, M. P., Tichy, S. E., and Fitzpatrick, P. F. (2005) J. Am. Chem. Soc. 127, 2062–2066). The structure of the enzyme trapped with cyanide during oxidation of 1-nitrohexane shows the presence of the modified flavin. A continuous hydrogen bond network connects the nitrogen of the CN-hexyl-FAD through the FAD 2’-hydroxyl to a chain of water molecules extending to the protein surface. Together, our complementary approaches provide strong evidence that the flavin cofactor is in the appropriate oxidation state and correlates well with the putative intermediate state observed within each of the crystal structures. Consequently, these results provide important structural descriptions of several steps along the nitroalkane oxidase reaction cycle. PMID:19265437

  13. Soluble CuA domain of cyanobacterial cytochrome c oxidase.

    PubMed

    Paumann, Martina; Lubura, Borjana; Regelsberger, Günther; Feichtinger, Markus; Köllensberger, Gunda; Jakopitsch, Christa; Furtmüller, Paul G; Peschek, Günter A; Obinger, Christian

    2004-03-12

    The genomes of several cyanobacteria show the existence of gene clusters encoding subunits I, II, and III of aa(3)-type cytochrome c oxidase. The enzyme occurs on both plasma and thylakoid membranes of these oxygenic phototrophic prokaryotes. Here we report the expression and purification of a truncated subunit II copper A (Cu(A)) domain (i.e. the electron entry and donor binding site) of cytochrome c oxidase from the cyanobacterium Synechocystis PCC 6803 in high yield. The water-soluble purple redox-active bimetallic center displays a relatively low standard reduction potential of 216 mV. Its absorption spectrum at pH 7 is similar to that of other soluble fragments from aa(3)-type oxidases, but the insensitivity of both absorbance and circular dichroism spectra to pH suggests that it is less exposed to the aqueous milieu compared with other Cu(A) domains. Oxidation of horse heart cytochrome c by the bimetallic center follows monophasic kinetics. At pH 7 and low ionic strength the bimolecular rate constant is (2.1 +/- 0.3) x 10(4) m-1 s(-1), and the rates decrease upon the increase of ionic strength. Sequence alignment and modeling of cyanobacterial Cu(A) domains show several peculiarities such as: (i) a large insertion located between the second transmembrane region and the putative hydrophobic cytochrome c docking site, (ii) the lack of acidic residues shown to be important in the interaction between cytochrome c and Paracoccus Cu(A) domain, and (iii) an extended C terminus similar to Escherichia coli ubiquinol oxidase.

  14. Crystal Structures of Intermediates in the Nitroalkane Oxidase Reaction

    SciTech Connect

    Heroux, A.; Bozinovski, D; Valley, M; Fitzpatrick, P; Orville, A

    2009-01-01

    The flavoenzyme nitroalkane oxidase is a member of the acyl-CoA dehydrogenase superfamily. Nitroalkane oxidase catalyzes the oxidation of neutral nitroalkanes to nitrite and the corresponding aldehydes or ketones. Crystal structures to 2.2 {angstrom} resolution or better of enzyme complexes with bound substrates and of a trapped substrate-flavin adduct are described. The D402N enzyme has no detectable activity with neutral nitroalkanes. The structure of the D402N enzyme crystallized in the presence of 1-nitrohexane or 1-nitrooctane shows the presence of the substrate in the binding site. The aliphatic chain of the substrate extends into a tunnel leading to the enzyme surface. The oxygens of the substrate nitro group interact both with amino acid residues and with the 2'-hydroxyl of the FAD. When nitroalkane oxidase oxidizes nitroalkanes in the presence of cyanide, an electrophilic flavin imine intermediate can be trapped (Valley, M. P., Tichy, S. E., and Fitzpatrick, P. F. (2005) J. Am. Chem. Soc. 127, 2062-2066). The structure of the enzyme trapped with cyanide during oxidation of 1-nitrohexane shows the presence of the modified flavin. A continuous hydrogen bond network connects the nitrogen of the CN-hexyl-FAD through the FAD 2'-hydroxyl to a chain of water molecules extending to the protein surface. Together, our complementary approaches provide strong evidence that the flavin cofactor is in the appropriate oxidation state and correlates well with the putative intermediate state observed within each of the crystal structures. Consequently, these results provide important structural descriptions of several steps along the nitroalkane oxidase reaction cycle.

  15. Economic Evaluation of Screening Strategies Combined with HPV Vaccination of Preadolescent Girls for the Prevention of Cervical Cancer in Vientiane, Lao PDR

    PubMed Central

    2016-01-01

    Background Several approaches to reduce the incidence of invasive cervical cancers exist. The approach adopted should take into account contextual factors that influence the cost-effectiveness of the available options. Objective To determine the cost-effectiveness of screening strategies combined with a vaccination program for 10-year old girls for cervical cancer prevention in Vientiane, Lao PDR. Methods A population-based dynamic compartment model was constructed. The interventions consisted of a 10-year old girl vaccination program only, or this program combined with screening strategies, i.e., visual inspection with acetic acid (VIA), cytology-based screening, rapid human papillomavirus (HPV) DNA testing, or combined VIA and cytology testing. Simulations were run over 100 years. In base-case scenario analyses, we assumed a 70% vaccination coverage with lifelong protection and a 50% screening coverage. The outcome of interest was the incremental cost per Disability-Adjusted Life Year (DALY) averted. Results In base-case scenarios, compared to the next best strategy, the model predicted that VIA screening of women aged 30–65 years old every three years, combined with vaccination, was the most attractive option, costing 2 544 international dollars (I$) per DALY averted. Meanwhile, rapid HPV DNA testing was predicted to be more attractive than cytology-based screening or its combination with VIA. Among cytology-based screening options, combined VIA with conventional cytology testing was predicted to be the most attractive option. Multi-way sensitivity analyses did not change the results. Compared to rapid HPV DNA testing, VIA had a probability of cost-effectiveness of 73%. Compared to the vaccination only option, the probability that a program consisting of screening women every five years would be cost-effective was around 60% and 80% if the willingness-to-pay threshold is fixed at one and three GDP per capita, respectively. Conclusions A VIA screening program

  16. Cloning and sequencing of two Ceriporiopsis subvermispora bicupin oxalate oxidase allelic isoforms: implications for the reaction specificity of oxalate oxidases and decarboxylases.

    PubMed

    Escutia, Marta R; Bowater, Laura; Edwards, Anne; Bottrill, Andrew R; Burrell, Matthew R; Polanco, Rubén; Vicuña, Rafael; Bornemann, Stephen

    2005-07-01

    Oxalate oxidase is thought to be involved in the production of hydrogen peroxide for lignin degradation by the dikaryotic white rot fungus Ceriporiopsis subvermispora. This enzyme was purified, and after digestion with trypsin, peptide fragments of the enzyme were sequenced using quadrupole time-of-flight mass spectrometry. Starting with degenerate primers based on the peptide sequences, two genes encoding isoforms of the enzyme were cloned, sequenced, and shown to be allelic. Both genes contained 14 introns. The sequences of the isoforms revealed that they were both bicupins that unexpectedly shared the greatest similarity to microbial bicupin oxalate decarboxylases rather than monocupin plant oxalate oxidases (also known as germins). We have shown that both fungal isoforms, one of which was heterologously expressed in Escherichia coli, are indeed oxalate oxidases that possess < or =0.2% oxalate decarboxylase activity and that the organism is capable of rapidly degrading exogenously supplied oxalate. They are therefore the first bicupin oxalate oxidases to have been described. Heterologous expression of active enzyme was dependent on the addition of manganese salts to the growth medium. Molecular modeling provides new and independent evidence for the identity of the catalytic site and the key amino acid involved in defining the reaction specificities of oxalate oxidases and oxalate decarboxylases.

  17. The microstructure and rheology of a model, thixotropic nanoparticle gel under steady shear and large amplitude oscillatory shear (LAOS)

    SciTech Connect

    Min Kim, Jung; Kate Gurnon, A.; Wagner, Norman J.; Eberle, Aaron P. R.; Porcar, Lionel

    2014-09-01

    The microstructure-rheology relationship for a model, thermoreversible nanoparticle gel is investigated using a new technique of time-resolved neutron scattering under steady and time-resolved large amplitude oscillatory shear (LAOS) flows. A 21 vol. % gel is tested with varying strength of interparticle attraction. Shear-induced structural anisotropy is observed as butterfly scattering patterns and quantified through an alignment factor. Measurements in the plane of flow show significant, local anisotropy develops with alignment along the compressional axis of flow, providing new insights into how gels flow. The microstructure-rheology relationship is analyzed through a new type of structure-Lissajous plot that shows how the anisotropic microstructure is responsible for the observed LAOS response, which is beyond a response expected for a purely viscous gel with constant structure. The LAOS shear viscosities are observed to follow the “Delaware-Rutgers” rule. Rheological and microstructural data are successfully compared across a broad range of conditions by scaling the shear rate by the strength of attraction, providing a method to compare behavior between steady shear and LAOS experiments. However, important differences remain between the microstructures measured at comparatively high frequency in LAOS experiments and comparable steady shear experiments that illustrate the importance of measuring the microstructure to properly interpret the nonlinear, dynamic rheological response.

  18. Genistein effect on xanthine oxidase activity.

    PubMed

    Sumbayev, V V

    2001-01-01

    Genistein was defined to be an allosteric xanthine oxidase inhibitor in the concentrations 0.1-4.0 microM and xanthine oxidase activator with superoxide scavenging activity in the concentrations 5.0 microM and higher. But the most effective allosteric binding with the highest affinity was observed in the genistein concentrations 0.1-1.0 microM. Intraperitoneum injections of genistein (500 micrograms/kg) during three days with the interval 24 hours decrease xanthine oxidase activity in the liver, lung and brain of the Vistar rats.

  19. Purification and characterization of a novel caffeine oxidase from Alcaligenes species.

    PubMed

    Mohapatra, B R; Harris, N; Nordin, R; Mazumder, A

    2006-09-18

    Alcaligenes species CF8 isolated from surface water of a lake produced a novel serine type metallo-caffeine oxidase. The optimal medium for caffeine oxidase production by this strain was (w/v) NaNO(3), 0.4%; KH(2)PO(4), 0.15%; Na(2)HPO(4), 0.05%; FeCl(3).6H(2)O, 0.0005%; CaCl(2).2H(2)O, 0.001%; MgSO(4).7H(2)O, 0.02%; glucose, 0.2%; caffeine, 0.05%, pH 7.5. The enzyme was purified to 63-fold by using ammonium sulfate precipitation, dialysis, ion exchange (diethylaminoethyl-cellulose) and gel filtration (Sephadex G-100) chromatographic techniques. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the purified caffeine oxidase was monomeric with a molecular mass of 65 kDa. The purified caffeine oxidase with a half-life of 20 min at 50 degrees C had maximal activity at pH 7.5 and 35 degrees C. The purified caffeine oxidase had strict substrate specificity towards caffeine (K(m) 8.94 microM and V(max) 47.62 U mg protein(-1)) and was not able to oxidize xanthine and hypoxanthine. The enzyme activity was not inhibited by para-chloromercuribenzoic acid, iodoacetamide, n-methylmaleimide, salicylic acid and sodium arsenite indicating the enzyme did not belong to xanthine oxidase family. The enzyme was not affected by Ca(+2), Mg(+2) and Na(+), but was completely inhibited by Co(+2), Cu(+2) and Mn(+2) at 1mM level. The novel caffeine oxidase isolated here from Alcaligenes species CF8 may be useful in biotechnological processes including waste treatment and biosensor development.

  20. EFFECTS OF HYDRAZINES ON THE METABOLISM OF CERTAIN AMINES AND AMINO ACIDS.

    DTIC Science & Technology

    AMINES, * AMINO ACIDS , *DIAMINE OXIDASE, TOXICITY, METABOLISM, METABOLISM, DIMETHYLHYDRAZINES, GLUTAMIC ACID, ENZYMES, PHARMACOLOGY, TRACER STUDIES, LABELED SUBSTANCES, RESPIRATION, GASTROINTESTINAL SYSTEM, RATS.

  1. "The Big Ones Swallow the Small Ones". Or Do They? Language-in-Education Policy and Ethnic Minority Education in the Lao PDR

    ERIC Educational Resources Information Center

    Cincotta-Segi, Angela Rose

    2011-01-01

    The Lao People's Democratic Republic (Lao PDR) is one of the most ethnically and linguistically diverse nations in Southeast Asia. The post-1975 government's policies regarding ethnic minority peoples are often considered to represent an ideological shift from earlier monocultural orientations to a discourse of interethnic equality and solidarity.…

  2. Prokaryotic origins for the mitochondrial alternative oxidase and plastid terminal oxidase nuclear genes.

    PubMed

    Finnegan, Patrick M; Umbach, Ann L; Wilce, Jackie A

    2003-12-18

    The mitochondrial alternative oxidase is a diiron carboxylate quinol oxidase (Dox) found in plants and some fungi and protists, but not animals. The plastid terminal oxidase is distantly related to alternative oxidase and is most likely also a Dox protein. Database searches revealed that the alpha-proteobacterium Novosphingobium aromaticivorans and the cyanobacteria Nostoc sp. PCC7120, Synechococcus sp. WH8102 and Prochlorococcus marinus subsp. pastoris CCMP1378 each possess a Dox homolog. Each prokaryotic protein conforms to the current structural models of the Dox active site and phylogenetic analyses suggest that the eukaryotic Dox genes arose from an ancestral prokaryotic gene.

  3. The family Plectopylidae (Gastropoda, Pulmonata) in Laos with the description of two new genera and a new species

    PubMed Central

    Páll-Gergely, Barna; Muratov, Igor V.; Asami, Takahiro

    2016-01-01

    Abstract Previously only a single plectopylid species, Helix laomontana L. Pfeiffer, 1862 was reported from Laos. Here we erect Naggsia Páll-Gergely & Muratov, gen. n. for Helix laomontana based on the description of its reproductive anatomy and radula. Another species, Hunyadiscus saurini Páll-Gergely, gen. & sp. n. is described from Northern Laos based on conchological data. Helix (Plectopylis) andersoni Blanford, 1869, which is known from the Burmese-Chinese border region, is also classified within Hunyadiscus Páll-Gergely, gen. n. A third species, Gudeodiscus (Gudeodiscus) messageri raheemi Páll-Gergely & Hunyadi, 2015 is reported from Laos for the first time. The new localities represent the westernmost sites of the genus Gudeodiscus. The reproductive anatomy of the latter species is described. PMID:27408542

  4. The first revision of the carnivorous land snail family Streptaxidae in Laos, with description of three new species (Pulmonata, Stylommatophora, Streptaxidae).

    PubMed

    Inkhavilay, Khamla; Siriboon, Thanit; Sutcharit, Chirasak; Rowson, Ben; Panha, Somsak

    2016-01-01

    The family Streptaxidae in Laos is revised. Twelve species are known, mainly from limestone areas, in the genera Discartemon Pfeiffer, 1856, Perrottetia Kobelt, 1905, Haploptychius Möllendorff, 1906, and Indoartemon Forcart, 1946. Three new species, Perrottetia unidentata sp. n. and Perrottetia megadentata sp. n. from northern and central Laos, and Indoartemon diodonta sp. n. from central Laos, are described. All eight species of these three genera previously recorded from Laos are revised and discussed based on examined material from Laos, Cambodia, Vietnam and Thailand. Type material was examined and lectotypes are designated. Details of genital anatomy and radulae are provided, including the first detailed genitalia and radula descriptions from Haploptychius. Two novelties in Streptaxidae, a vaginal caecum, and the occurrence of aphallic individuals, are reported from Haploptychius pellucens (Pfeiffer, 1863).

  5. The first revision of the carnivorous land snail family Streptaxidae in Laos, with description of three new species (Pulmonata, Stylommatophora, Streptaxidae)

    PubMed Central

    Inkhavilay, Khamla; Siriboon, Thanit; Sutcharit, Chirasak; Rowson, Ben; Panha, Somsak

    2016-01-01

    Abstract The family Streptaxidae in Laos is revised. Twelve species are known, mainly from limestone areas, in the genera Discartemon Pfeiffer, 1856, Perrottetia Kobelt, 1905, Haploptychius Möllendorff, 1906, and Indoartemon Forcart, 1946. Three new species, Perrottetia unidentata sp. n. and Perrottetia megadentata sp. n. from northern and central Laos, and Indoartemon diodonta sp. n. from central Laos, are described. All eight species of these three genera previously recorded from Laos are revised and discussed based on examined material from Laos, Cambodia, Vietnam and Thailand. Type material was examined and lectotypes are designated. Details of genital anatomy and radulae are provided, including the first detailed genitalia and radula descriptions from Haploptychius. Two novelties in Streptaxidae, a vaginal caecum, and the occurrence of aphallic individuals, are reported from Haploptychius pellucens (Pfeiffer, 1863). PMID:27408533

  6. Land Use and Water Quality Along a Mekong Tributary in Northern Lao P.D.R.

    NASA Astrophysics Data System (ADS)

    Ribolzi, Olivier; Cuny, Juliette; Sengsoulichanh, Phonexay; Mousquès, Claire; Soulileuth, Bounsamai; Pierret, Alain; Huon, Sylvain; Sengtaheuanghoung, Oloth

    2011-02-01

    Improving access to clean water has the potential to make a major contribution toward poverty reduction in rural communities of Lao P.D.R. This study focuses on stream water quality along a Mekong basin tributary, the Houay Xon that flows within a mountainous, mosaic land-use catchment of northern Lao P.D.R. To compare direct water quality measurements to the perception of water quality within the riparian population, our survey included interviews of villagers. Water quality was found to vary greatly depending on the location along the stream. Overall, it reflected the balance between the stream self-cleaning potential and human pressure on the riparian zone: (i) high bacteria and suspended load levels occurred where livestock are left to free-range within the riparian zone; (ii) very low oxygen content and high bacteriological contamination prevailed downstream from villages; (iii) high concentrations of bacteria were consistently observed along urbanized banks; (iv) low oxygen content were associated with the discharge of organic-rich wastewater from a small industrial plant; (v) very high suspended load and bacteria levels occurred during flood events due to soil erosion from steep cultivated hill slopes. Besides these human induced pollutions we also noted spontaneous enrichments in metals in wetland areas fed by dysoxic groundwater. These biophysical measurements were in agreement with the opinions expressed by the majority of the interviewees who reported poor and decreasing water quality in the Houay Xon catchment. Based on our survey, we propose recommendations to improve or maintain stream water quality in the uplands of northern Lao P.D.R.

  7. Normal state electronic properties of LaO1-x Fx BiS2 superconductors

    NASA Astrophysics Data System (ADS)

    Querales-Flores, J. D.; Ventura, C. I.; Citro, R.; Rodríguez-Núñez, J. J.

    2016-05-01

    A good description of the electronic structure of BiS2-based superconductors is essential to understand their phase diagram, normal state and superconducting properties. To describe the first reports of normal state electronic structure features from angle resolved photoemission spectroscopy (ARPES) in LaO1-x Fx BiS2, we used a minimal microscopic model to study their low energy properties. It includes the two effective tight-binding bands proposed by Usui et al., Phys. Rev. B, 86, 2012, 220501(R), and we added moderate intra- and inter-orbital electron correlations related to Bi-(pY, pX) and S-(pY, pX) orbitals. We calculated the electron Green's functions using their equations of motion, which we decoupled in second-order of perturbations on the correlations. We determined the normal state spectral density function and total density of states for LaO1-x Fx BiS2, focusing on the description of the k-dependence, effect of doping, and the prediction of the temperature dependence of spectral properties. Including moderate electron correlations, improves the description of the few experimental ARPES and soft X-ray photoemission data available for LaO1-x Fx BiS2. Our analytical approximation enabled us to calculate the spectral density around the conduction band minimum at k→0 =(0.45 π , 0.45 π), and to predict the temperature dependence of the spectral properties at different BZ points, which might be verified by temperature-dependent ARPES.

  8. Project CHECO Southeast Asia Report. USAF Control of Airstrikes in Support of Indigenous Lao Ground Forces

    DTIC Science & Technology

    1972-07-19

    Communists 1 U.S. Assistance Continues: Waterpump • • • • 6 Disruption of the 1962 Geneva Agreement • • • 7 Use of Thai, Air America, and Waterpump T-28...5. Air America/ Waterpump Compound at Udorn RTAFB, Thailand 6. Fairchild-Hiller/Pilatus Turbo Porter Flown by Air 7. B. 9. 10. 11. 12. 13...to Kong Le’s neutralist forces. U.S. A~sistance Continues: WATERPUMP The United States agreed to the political neutralization of Laos and, in 1962

  9. Orientia, rickettsia, and leptospira pathogens as causes of CNS infections in Laos: a prospective study

    PubMed Central

    Dittrich, Sabine; Rattanavong, Sayaphet; Lee, Sue J; Panyanivong, Phonepasith; Craig, Scott B; Tulsiani, Suhella M; Blacksell, Stuart D; Dance, David A B; Dubot-Pérès, Audrey; Sengduangphachanh, Amphone; Phoumin, Phonelavanh; Paris, Daniel H; Newton, Paul N

    2015-01-01

    Summary Background Scrub typhus (caused by Orientia tsutsugamushi), murine typhus (caused by Rickettsia typhi), and leptospirosis are common causes of febrile illness in Asia; meningitis and meningoencephalitis are severe complications. However, scarce data exist for the burden of these pathogens in patients with CNS disease in endemic countries. Laos is representative of vast economically poor rural areas in Asia with little medical information to guide public health policy. We assessed whether these pathogens are important causes of CNS infections in Laos. Methods Between Jan 10, 2003, and Nov 25, 2011, we enrolled 1112 consecutive patients of all ages admitted with CNS symptoms or signs requiring a lumbar puncture at Mahosot Hospital, Vientiane, Laos. Microbiological examinations (culture, PCR, and serology) targeted so-called conventional bacterial infections (Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, S suis) and O tsutsugamushi, Rickettsia typhi/Rickettsia spp, and Leptospira spp infections in blood or cerebrospinal fluid (CSF). We analysed and compared causes and clinical and CSF characteristics between patient groups. Findings 1051 (95%) of 1112 patients who presented had CSF available for analysis, of whom 254 (24%) had a CNS infection attributable to a bacterial or fungal pathogen. 90 (35%) of these 254 infections were caused by O tsutsugamushi, R typhi/Rickettsia spp, or Leptospira spp. These pathogens were significantly more frequent than conventional bacterial infections (90/1051 [9%] vs 42/1051 [4%]; p<0·0001) by use of conservative diagnostic definitions. CNS infections had a high mortality (236/876 [27%]), with 18% (13/71) for R typhi/Rickettsia spp, O tsutsugamushi, and Leptospira spp combined, and 33% (13/39) for conventional bacterial infections (p=0·076). Interpretation Our data suggest that R typhi/Rickettsia spp, O tsutsugamushi, and Leptospira spp infections are important causes of CNS infections in Laos

  10. Effects of ascorbic acid on carcinogenicity and acute toxicity of nickel subsulfide, and on tumor transplants growth in gulonolactone oxidase knock-out mice and wild-type C57BL mice.

    PubMed

    Kasprzak, Kazimierz S; Diwan, Bhalchandra A; Kaczmarek, Monika Z; Logsdon, Daniel L; Fivash, Mathew J; Salnikow, Konstantin

    2011-11-15

    The aim of this study was to test a hypothesis that ascorbate depletion could enhance carcinogenicity and acute toxicity of nickel. Homozygous L-gulono--lactone oxidase gene knock-out mice (Gulo-/- mice) unable to produce ascorbate and wild-type C57BL mice (WT mice) were injected intramuscularly with carcinogenic nickel subsulfide (Ni₃S₂), and observed for the development of injection site tumors for 57 weeks. Small pieces of one of the induced tumors were transplanted subcutaneously into separate groups of Gulo-/- and WT mice and the growth of these tumors was measured for up to 3 months. The two strains of mice differed significantly with regard to (1) Ni₃S₂ carcinogenesis: Gulo-/- mice were 40% more susceptible than WT mice; and (2) transplanted tumors development: Gulo-/- mice were more receptive to tumor growth than WT mice, but only in terms of a much shorter tumor latency; later in the exponential phase of growth, the growth rates were the same. And, with adequate ascorbate supplementation, the two strains were equally susceptible to acute toxicity of Ni₃S₂. Statistically significant effects of dietary ascorbate dosing levels were the following: (1) reduction in ascorbate supplementation increased acute toxicity of Ni₃S₂ in Gulo-/- mice; (2) ascorbate supplementation extended the latency of transplanted tumors in WT mice. In conclusion, the lack of endogenous ascorbate synthesis makes Gulo-/- mice more susceptible to Ni₃S₂ carcinogenesis. Dietary ascorbate tends to attenuate acute toxicity of Ni₃S₂ and to extend the latency of transplanted tumors. The latter effects may be of practical importance to humans and thus deserve further studies.

  11. Involvement of Polyamine Oxidase in Wound Healing12[W

    PubMed Central

    Angelini, Riccardo; Tisi, Alessandra; Rea, Giuseppina; Chen, Martha M.; Botta, Maurizio; Federico, Rodolfo; Cona, Alessandra

    2008-01-01

    Hydrogen peroxide (H2O2) is involved in plant defense responses that follow mechanical damage, such as those that occur during herbivore or insect attacks, as well as pathogen attack. H2O2 accumulation is induced during wound healing processes as well as by treatment with the wound signal jasmonic acid. Plant polyamine oxidases (PAOs) are H2O2 producing enzymes supposedly involved in cell wall differentiation processes and defense responses. Maize (Zea mays) PAO (ZmPAO) is a developmentally regulated flavoprotein abundant in primary and secondary cell walls of several tissues. In this study, we investigated the effect of wounding on ZmPAO gene expression in the outer tissues of the maize mesocotyl and provide evidence that ZmPAO enzyme activity, protein, and mRNA levels increased in response to wounding as well as jasmonic acid treatment. Histochemically detected ZmPAO activity especially intensified in the epidermis and in the wound periderm, suggesting a tissue-specific involvement of ZmPAO in wound healing. The role played by ZmPAO-derived H2O2 production in peroxidase-mediated wall stiffening events was further investigated by exploiting the in vivo use of N-prenylagmatine (G3), a selective and powerful ZmPAO inhibitor, representing a reliable diagnostic tool in discriminating ZmPAO-mediated H2O2 production from that generated by peroxidase, oxalate oxidase, or by NADPH oxidase activity. Here, we demonstrate that G3 inhibits wound-induced H2O2 production and strongly reduces lignin and suberin polyphenolic domain deposition along the wound, while it is ineffective in inhibiting the deposition of suberin aliphatic domain. Moreover, ZmPAO ectopic expression in the cell wall of transgenic tobacco (Nicotiana tabacum) plants strongly enhanced lignosuberization along the wound periderm, providing evidence for a causal relationship between PAO and peroxidase-mediated events during wound healing. PMID:17993545

  12. Joint malaria surveys lead towards improved cross-border cooperation between Savannakhet province, Laos and Quang Tri province, Vietnam

    PubMed Central

    2012-01-01

    Background In Savannakhet province, Laos and Quang Tri province, Vietnam, malaria is still an important health problem and most cases are found in the mountainous, forested border areas where ethnic minority groups live. The objectives of this study were to obtain a better joint understanding of the malaria situation along the border and, on the basis of that, improve malaria control methods through better cooperation between the two countries. Methods Fourteen villages in Savannakhet and 22 villages in Quang Tri were randomly selected within 5 km from the border where a blood survey for microscopic diagnosis (n = 1256 and n = 1803, respectively), household interviews (n = 400, both sides) and vector surveys were conducted between August and October 2010. Satellite images were used to examine the forest density around the study villages. Results Malaria prevalence was significantly higher in Laos (5.2%) than in Vietnam (1.8%) and many other differences were found over the short distance across the border. Bed net coverage was high (> 90%) in both Laos and Vietnam but, while in Laos more than 60% of the nets were long-lasting insecticide-treated, Vietnam used indoor residual spraying in this area and the nets were untreated. Anopheles mosquitoes were more abundant in Laos than in Vietnam, especially many Anopheles dirus were captured in indoor light traps while none were collected in Vietnam. The forest cover was higher around the Lao than the Vietnamese villages. After this study routine exchange of malaria surveillance data was institutionalized and for the first time indoor residual spraying was applied in some Lao villages. Conclusions The abundance of indoor-collected An. dirus on the Laos side raises doubts about the effectiveness of a sole reliance on long-lasting insecticide-treated nets in this area. Next to strengthening the early detection, correct diagnosis and prompt, adequate treatment of malaria infections, it is recommended to test

  13. 4-Hydroxyanisole: the most suitable monophenolic substrate for determining spectrophotometrically the monophenolase activity of polyphenol oxidase from fruits and vegetables.

    PubMed

    Espín, J C; Tudela, J; García-Cánovas, F

    1998-05-15

    A continuous spectrophotometric method for determining the monophenolase activity of polyphenol oxidase from several plant sources is described. This assay method is based on the coupling reaction between 3-methyl-2-benzothiazolinone hydrazone and the quinone product of the oxidation of 4-hydroxyanisole in the presence of polyphenol oxidase. 4-Hydroxyanisole proved to be the best monophenol assayed to measure the monophenolase activity of polyphenol oxidase from apple, artichoke, avocado, medlar, pear, and strawberry. Kinetic constants of 4-hydroxyanisole were compared to those of p-hydroxyphenyl propionic acid, a very sensitive monophenol previously reported to assay the monophenolase activity of polyphenol oxidase from apple, pear, and mushroom. The high values of the maximum steady state rate obtained for 4-hydroxyanisole suggest the existence of high catalytic constant toward this monophenol. These kinetic values were supported by nuclear magnetic resonance assays which predicted the highest reactivity of 4-hydroxyanisole. Therefore nuclear magnetic resonance assays proved to be a valuable and useful tool to predict the best monophenolic substrate for plant polyphenol oxidases. The 3-methyl-2-benzothiazlolinone-adduct for 4-hydroxyanisole was stable, with high molar absorptivity at the optimum pHs of the polyphenol oxidases assayed. All this together makes the use of 4-hydroxyanisol as monophenolic substrate and 3-methyl-2-benzothiazolinone as coupling reagent the most sensitive and precise assay method up to date reported in the literature to determine the monophenolas activity of polyphenol oxidase from fruits and vegetables.

  14. Childhood encephalomyopathy with cytochrome c oxidase deficiency, ataxia, muscle wasting, and mental impairment.

    PubMed

    Angelini, C; Bresolin, N; Pegolo, G; Bet, L; Rinaldo, P; Trevisan, C; Vergani, L

    1986-08-01

    The son of third cousins was normal until age 2 when he had difficulty walking. At age 8 there was limb weakness, ataxia, loss of tendon reflexes, dislalia, and he was mildly retarded. During fasting, urinary organic acid excretion was abnormally high. Cytochrome c oxidase activity in muscle was 7% of the normal mean. The enzyme in platelets was 16% of controls with a decreased cytochrome aa3 peak. These data suggest an autosomal recessive transmission of this variant of cytochrome c oxidase deficiency.

  15. Immunological and molecular comparison of polyphenol oxidase in Rosaceae fruit trees.

    PubMed

    Haruta, M; Murata, M; Kadokura, H; Homma, S

    1999-03-01

    An antibody raised against apple polyphenol oxidase (PPO) cross-reacted with PPOs from Japanese pear (Pyrus pyrifolia), pear (Pyrus communis), peach (Prunus persica), Chinese quince (Pseudocydonia sinensis) and Japanese loquat (Eriobotrya japonica). Core fragments (681 bp) of the corresponding PPO genes were amplified and characterized. The deduced protein sequences showed identities of 85.3 to 97.5%. Chlorogenic acid oxidase activity of these PPOs showed higher activities when assayed at pH 4 than at pH 6. These results indicate that PPOs in Rosaceae plants are structurally and enzymatically similar.

  16. Pentamines as substrate for human spermine oxidase

    PubMed Central

    Takao, Koichi; Shirahata, Akira; Samejima, Keijiro; Casero, Robert A.; Igarashi, Kazuei; Sugita, Yoshiaki

    2013-01-01

    Substrate activities of various linear polyamines to human spermine oxidase (hSMO) were investigated. The activities were evaluated by monitoring the amount of H2O2 released from sample polyamines by hSMO. H2O2 was measured by a HPLC method that analyzed fluorescent dimers derived from the oxidation of homovanillic acid in the presence of horseradish peroxidase. Six triamines were tested and were found not to be hSMO substrates. Of sixteen tetramines tested, spermine (Spm) was the most active substrate, followed by homospermine and N-butylated Spm. Pentamines showed a characteristic pattern of substrate activity. Of thirteen pentamines tested, 3343 showed higher substrate activity than Spm, and 4343 showed similar activity to Spm. The activities of the other pentamines were as follows: 3443, 4443, 4344, 3344, 4334, 4444, and 3334 (in decreasing order). Product amines released from these pentamines by hSMO were then analyzed by HPLC. Triamine was the only observed product, and the amount of triamine was nearly equivalent to that of released H2O2. A marked difference in the pH dependency curves between tetramines and pentamines suggested that hSMO favored reactions with a non-protonated secondary nitrogen at the cleavage site. The Km and Vmax values for Spm and 3343 at pH 7.0 and 9.0 were consistent with the higher substrate activity of 3343 compared to Spm, as well as with the concept of a non-protonated secondary nitrogen at the cleavage site being preferred, and 3343 was well degraded at a physiological pH by hSMO. PMID:23449327

  17. Effects of ascorbic acid on carcinogenicity and acute toxicity of nickel subsulfide, and on tumor transplants growth in gulonolactone oxidase knock-out mice and wild-type C57BL mice

    SciTech Connect

    Kasprzak, Kazimierz S.; Diwan, Bhalchandra A.; Kaczmarek, Monika Z.; Logsdon, Daniel L.; Fivash, Mathew J.; Salnikow, Konstantin

    2011-11-15

    The aim of this study was to test a hypothesis that ascorbate depletion could enhance carcinogenicity and acute toxicity of nickel. Homozygous L-gulono- < gamma > -lactone oxidase gene knock-out mice (Gulo-/- mice) unable to produce ascorbate and wild-type C57BL mice (WT mice) were injected intramuscularly with carcinogenic nickel subsulfide (Ni{sub 3}S{sub 2}), and observed for the development of injection site tumors for 57 weeks. Small pieces of one of the induced tumors were transplanted subcutaneously into separate groups of Gulo-/- and WT mice and the growth of these tumors was measured for up to 3 months. The two strains of mice differed significantly with regard to (1) Ni{sub 3}S{sub 2} carcinogenesis: Gulo-/- mice were 40% more susceptible than WT mice; and (2) transplanted tumors development: Gulo-/- mice were more receptive to tumor growth than WT mice, but only in terms of a much shorter tumor latency; later in the exponential phase of growth, the growth rates were the same. And, with adequate ascorbate supplementation, the two strains were equally susceptible to acute toxicity of Ni{sub 3}S{sub 2}. Statistically significant effects of dietary ascorbate dosing levels were the following: (1) reduction in ascorbate supplementation increased acute toxicity of Ni{sub 3}S{sub 2} in Gulo-/- mice; (2) ascorbate supplementation extended the latency of transplanted tumors in WT mice. In conclusion, the lack of endogenous ascorbate synthesis makes Gulo-/- mice more susceptible to Ni{sub 3}S{sub 2} carcinogenesis. Dietary ascorbate tends to attenuate acute toxicity of Ni{sub 3}S{sub 2} and to extend the latency of transplanted tumors. The latter effects may be of practical importance to humans and thus deserve further studies. -- Highlights: Black-Right-Pointing-Pointer Ascorbate depletion enhances carcinogenicity and acute toxicity of nickel. Black-Right-Pointing-Pointer Gulo-/- mice unable to synthesize ascorbate were used in this study. Black

  18. The infective causes of hepatitis and jaundice amongst hospitalised patients in Vientiane, Laos.

    PubMed

    Syhavong, Bounkong; Rasachack, Bouachanh; Smythe, Lee; Rolain, Jean-Marc; Roque-Afonso, Anne-Marie; Jenjaroen, Kemajittra; Soukkhaserm, Vimone; Phongmany, Simmaly; Phetsouvanh, Rattanaphone; Soukkhaserm, Sune; Thammavong, Te; Mayxay, Mayfong; Blacksell, Stuart D; Barnes, Eleanor; Parola, Philippe; Dussaix, Elisabeth; Raoult, Didier; Humphreys, Isla; Klenerman, Paul; White, Nicholas J; Newton, Paul N

    2010-07-01

    There is little information on the diverse infectious causes of jaundice and hepatitis in the Asiatic tropics. Serology (hepatitis A, B, C and E, leptospirosis, dengue, rickettsia), antigen tests (dengue), PCR assays (hepatitis A, C and E) and blood cultures (septicaemia) were performed on samples from 392 patients admitted with jaundice or raised transaminases (> or =x3) to Mahosot Hospital, Vientiane, Laos over 3 years. Conservative definitions suggested diagnoses of dengue (8.4%), rickettsioses (7.3%), leptospirosis (6.8%), hepatitis B (4.9%), hepatitis C (4.9%), community-acquired septicaemia (3.3%) and hepatitis E (1.6%). Although anti-hepatitis A virus (HAV) IgM antibody results suggested that 35.8% of patients had acute HAV infections, anti-HAV IgG antibody avidity and HAV PCR suggested that 82% had polyclonal activation and not acute HAV infections. Scrub typhus, murine typhus or leptospirosis were present in 12.8% of patients and were associated with meningism and relatively low AST and ALT elevation. These patients would be expected to respond to empirical doxycycline therapy which, in the absence of virological diagnosis and treatment, may be an appropriate cost-effective intervention in Lao patients with jaundice/hepatitis.

  19. Challenges and dilemmas: fieldwork with upland minorities in socialist Vietnam, Laos and southwest China.

    PubMed

    Turner, Sarah

    2010-01-01

    The Chinese, Vietnamese and Lao spaces within the upland Southeast Asian massif, sheltering over 80 million people belonging to geographically dispersed and politically fragmented minority populations, have only recently reopened to overseas academic endeavours. Undertaking social sciences research there among ethnic minority groups is underscored by a specific set of challenges, dilemmas, and negotiations. This special issue brings together Western academics and post-fieldwork doctoral students from the realms of social anthropology and human geography, who have conducted in-depth fieldwork among ethnic minorities in upland southwest China, northern Vietnam, and southern Laos. The articles provide insights into the struggles and constraints they faced in the field, set against an understanding of the historical context of field research in these locales. In this unique context that nowadays interweaves economic liberalisation with centralised and authoritarian political structures, the authors explore how they have negotiated and manoeuvred access to ethnic minority voices in complex cultural configurations. The ethical challenges raised and methodological reflections offered will be insightful for others conducting fieldwork in the socialist margins of the Southeast Asian massif and beyond. This specific context is introduced here, followed by a critique of the literature on the core themes that contributors raise.

  20. Household, hotel and market waste audits for composting in Vietnam and Laos.

    PubMed

    Byer, Philip H; Hoang, Chi Phuong; Nguyen, Thi Thuc Thuy; Chopra, Sangeeta; Maclaren, Virginia; Haight, Murray

    2006-10-01

    In Da Nang and Ha Long, Vietnam and in Vientiane, Laos, there was interest by local authorities in separating and composting waste in order to reduce environmental and health problems at the local landfills and to produce a soil conditioner for local agricultural use. To assist in the planning of composting projects, three studies were carried out to estimate waste quantities and composition. 1. A 9-day audit of waste from 45 vendors in a market in Vientiane, the capital of Laos. The total quantity of waste and the quantity in each of nine categories were estimated for each of six different types of vendors. 2. A 7-day audit of waste disposed by three hotels in the tourist area of Ha Long, Vietnam. Waste quantities were estimated in total, on a per guest basis, and in three main categories: compostables, recyclables and miscellaneous. 3. A 7-day audit of waste collected from 74 households in Da Nang, the fourth largest city in Vietnam. Waste from each household was separated into compostable and non-compostable waste. Over 60% of each waste source comprised compostable waste and this was considered significant enough to warrant further planning of composting operations.

  1. Mapping mental health finances in Ghana, Uganda, Sri Lanka, India and Lao PDR

    PubMed Central

    2010-01-01

    Background Limited evidence about mental health finances in low and middle-income countries is a key challenge to mental health care policy initiatives. This study aimed to map mental health finances in Ghana, Uganda, India (Kerala state), Sri Lanka and Lao PDR focusing on how much money is available for mental health, how it is spent, and how this impacts mental health services. Methods A researcher in each region reviewed public mental health-related budgets and interviewed key informants on government mental health financing. A total of 43 key informant interviews were conducted. Quantitative data was analyzed in an excel matrix using descriptive statistics. Key informant interviews were coded a priori against research questions. Results National ring-fenced budgets for mental health as a percentage of national health spending for 2007-08 is 1.7% in Sri Lanka, 3.7% in Ghana, 2.0% in Kerala (India) and 6.6% in Uganda. Budgets were not available in Lao PDR. The majority of ring-fenced budgets (76% to 100%) is spent on psychiatric hospitals. Mental health spending could not be tracked beyond the psychiatric hospital level due to limited information at the health centre and community levels. Conclusions Mental health budget information should be tracked and made publically accessible. Governments can adapt WHO AIMS indicators for reviewing national mental health finances. Funding allocations work more effectively through decentralization. Mental health financing should reflect new ideas emerging from community based practice in LMICs. PMID:20507558

  2. Patterns of Flavivirus Seroprevalence in the Human Population of Northern Laos

    PubMed Central

    Conlan, James V.; Vongxay, Khamphouth; Khamlome, Boualam; Jarman, Richard G.; Gibbons, Robert V.; Fenwick, Stanley G.; Thompson, R. C. A.; Blacksell, Stuart D.

    2015-01-01

    A total of 1,136 samples from 289 households in four provinces in northern Laos were subjected to Japanese encephalitis virus (JEV) and dengue virus hemagglutination inhibition (DENV HI). Overall, antibodies to JEV were detected by HI in 620 (54.6%) of 1,136 people; of which 217 (19.1%) had HI activity against JEV only. Antibodies to DENV4 were detected by HI in 526 (46.3%) of 1,136 people; of which 124 (10.9%) had HI activity against DENV4 only. Antibodies to DENV1–3 were detected by HI in 296 (26.1%), 274 (24.1%), and 283 (24.9) of 1,136 people, respectively; of which 7, 1, and 0, respectively, had HI activity against DENV1–3 only. JEV was the most prevalent Flavivirus in Oudomxay, Luangprabang, and Huaphan provinces and DENV4 was the most prevalent in Xiengkhouang province. Seroprevalence for JEV increased with increasing age and wealth and was higher in villages where rice was cultivated in paddy fields and highest for people of Lao-Tai ethnicity. PMID:26304925

  3. No Evidence for Spread of Plasmodium falciparum Artemisinin Resistance to Savannakhet Province, Southern Laos

    PubMed Central

    Mayxay, Mayfong; Khanthavong, Maniphone; Chanthongthip, Odai; Imwong, Mallika; Lee, Sue J.; Stepniewska, Kasia; Soonthornsata, Bongkot; Pongvongsa, Tiengkham; Phompida, Samlane; Hongvanthong, Bouasy; Ringwald, Pascal; White, Nicholas J.; Newton, Paul N.

    2012-01-01

    We conducted an open-label, randomized clinical trial to assess parasite clearance times (PCT) and the efficacy of 4 mg/kg (group 1, n = 22) and 2 mg/kg (group 2, n = 22) of oral artesunate for three days followed by artemether-lumefantrine in patients with uncomplicated Plasmodium falciparum malaria at Xepon Interdistrict Hospital, Savannakhet Province in southern Laos. Slides were read in duplicate. The overall mean (95% confidence interval; range) PCT in hours was 23.2 (21.2–25.3; 12–46) and 22.4 (20.3–24.5; 12–46) for the first and second microscopists, respectively (P = 0.57). Ten (23%) patients remained parasitemic on day 1 after treatment (4 [18%] in group 1 and 6 [27%] in group 2; P = 0.47). No patient had patent asexual parasitemia on the second and third days of treatment. The 42-day polymerase chain reaction–corrected cure rates were 100% in both treatment groups. Serious adverse events did not develop during or after treatment in any patients. In conclusion, no evidence of P. falciparum in vivo resistance to artesunate was found in southern Laos. PMID:22403308

  4. Arabidopsis ent-kaurene oxidase catalyzes three steps of gibberellin biosynthesis.

    PubMed

    Helliwell, C A; Poole, A; Peacock, W J; Dennis, E S

    1999-02-01

    The Arabidopsis GA3 cDNA was expressed in yeast (Saccharomyces cerevisiae) and the ability of the transformed yeast cells to metabolize ent-kaurene was tested. We show by full-scan gas chromatography-mass spectrometry that the transformed cells produce ent-kaurenoic acid, and demonstrate that the single enzyme GA3 (ent-kaurene oxidase) catalyzes the three steps of gibberellin biosynthesis from ent-kaurene to ent-kaurenoic acid.

  5. Concentrates and mantle xenocrysts from the Lao river Guinea and reconstructions of the mantle structure

    NASA Astrophysics Data System (ADS)

    Afanasiev, Valentin; Ashchepkov, Igor; Nikolenko, Eeugeny

    2015-04-01

    The discovery of the kimberlite dykes in Quinea in the basin of the Lao river means finding of the new diamondiferous kimberlite field in the West Africa. It is locating 100 km SW from Bubudu and contains large dykes and placers in Lao river. The kimberlite concentrate and diamondiferous placers are containing pyropes, chromites, Ilmenites and Cr diosides and low Cr- pyroxenes. Two river placers in Lao and Bobeko and newly discovered dyke slightly differ in compositions of minerals. mainly in representatives of the minerals though their compositional trends are in general similar. The concentrates from and Druzhba pipe (Bunudu) contains mainly ilmenite and more are pyropes. Garnets from all localities are close and belong mainly to the lherzolite field to 10 wt%Cr2O3. But the dyke contains essential amount of harzburgitic garnets starting from 2 %wt Cr2O3 and they became prevailing from 6 wt %Cr2O3. There are also megacrystic low - Cr pyropes in dyke concentrate. Dyke is rich in peridotites and coarse grained garnet pyroxenite xenoliths which are ranging from the low Cr -to Cr -diopside type Chromites from Dyke are Ti - low but are often Al rich. While chromites from Bobeko and especially Lao placers define the Cr- rich trend from 60 to 40 wt%Cr2O3 and demonstrate the deviation to ulvospinel trends with increasing of Al2O3 . Cr - Diopsides clinopyroxenites trace the Fe- Ti-Na-Al enrichment trend. Ilmenites from three localities - define close trends splitting to the two intervals 60-40 wt% TiO2 and 33-27 TiO2 which are enriched in Cr2O3 to 5wt% reflecting the crystallization of megacrystalline association at the lithosphere base and Ilm metasomatic vein stockwark near the Moho in pre-eruption feeding system. The Dyke ilmenites are Mg rich and mainly are captured from the deep part of the mantle section. Babeko and Druzhba localities are similar variations of ilmenite trends. Some ilmenites from Lao and Druzhba are Mn - rich and are less in Cr possibly reflecting

  6. Three-dimensional organization of three-domain copper oxidases: A review

    NASA Astrophysics Data System (ADS)

    Zhukhlistova, N. E.; Zhukova, Yu. N.; Lyashenko, A. V.; Zaĭtsev, V. N.; Mikhaĭlov, A. M.

    2008-01-01

    “Blue” copper-containing proteins are multidomain proteins that utilize a unique redox property of copper ions. Among other blue multicopper oxidases, three-domain oxidases belong to the group of proteins that exhibit a wide variety of compositions in amino acid sequences, functions, and occurrences in organisms. This paper presents a review of the data obtained from X-ray diffraction investigations of the three-dimensional structures of three-domain multicopper oxidases, such as the ascorbate oxidase catalyzing oxidation of ascorbate to dehydroascorbate and its three derivatives; the multicopper oxidase CueO (the laccase homologue); the laccases isolated from the basidiomycetes Coprinus cinereus, Trametes versicolor, Coriolus zonatus, Cerrena maxima, and Rigidoporus lignosus and the ascomycete Melanocarpus albomyces; and the bacterial laccases CotA from the endospore coats of Bacillus subtilis. A comparison of the molecular structures of the laccases of different origins demonstrates that, structurally, these objects are highly conservative. This obviously indicates that the catalytic activity of the enzymes under consideration is characterized by similar mechanisms.

  7. Single mutations that redirect internal proton transfer in the ba3 oxidase from Thermus thermophilus.

    PubMed

    Smirnova, Irina; Chang, Hsin-Yang; von Ballmoos, Christoph; Ädelroth, Pia; Gennis, Robert B; Brzezinski, Peter

    2013-10-08

    The ba3-type cytochrome c oxidase from Thermus thermophilus is a membrane-bound proton pump. Results from earlier studies have shown that with the aa3-type oxidases proton uptake to the catalytic site and "pump site" occurs simultaneously. However, with ba3 oxidase the pump site is loaded before proton transfer to the catalytic site because the proton transfer to the latter is slower than that with the aa3 oxidases. In addition, the timing of formation and decay of catalytic intermediates is different in the two types of oxidases. In the present study, we have investigated two mutant ba3 CytcOs in which residues of the proton pathway leading to the catalytic site as well as the pump site were exchanged, Thr312Val and Tyr244Phe. Even though ba3 CytcO uses only a single proton pathway for transfer of the substrate and "pumped" protons, the amino-acid residue substitutions had distinctly different effects on the kinetics of proton transfer to the catalytic site and the pump site. The results indicate that the rates of these reactions can be modified independently by replacement of single residues within the proton pathway. Furthermore, the data suggest that the Thr312Val and Tyr244Phe mutations interfere with a structural rearrangement in the proton pathway that is rate limiting for proton transfer to the catalytic site.

  8. Fibromodulin Interacts with Collagen Cross-linking Sites and Activates Lysyl Oxidase*

    PubMed Central

    Bihan, Dominique; Bonna, Arkadiusz; Rubin, Kristofer; Farndale, Richard W.

    2016-01-01

    The hallmark of fibrotic disorders is a highly cross-linked and dense collagen matrix, a property driven by the oxidative action of lysyl oxidase. Other fibrosis-associated proteins also contribute to the final collagen matrix properties, one of which is fibromodulin. Its interactions with collagen affect collagen cross-linking, packing, and fibril diameter. We investigated the possibility that a specific relationship exists between fibromodulin and lysyl oxidase, potentially imparting a specific collagen matrix phenotype. We mapped the fibromodulin-collagen interaction sites using the collagen II and III Toolkit peptide libraries. Fibromodulin interacted with the peptides containing the known collagen cross-linking sites and the MMP-1 cleavage site in collagens I and II. Interestingly, the interaction sites are closely aligned within the quarter-staggered collagen fibril, suggesting a multivalent interaction between fibromodulin and several collagen helices. Furthermore, we detected an interaction between fibromodulin and lysyl oxidase (a major collagen cross-linking enzyme) and mapped the interaction site to 12 N-terminal amino acids on fibromodulin. This interaction also increases the activity of lysyl oxidase. Together, the data suggest a fibromodulin-modulated collagen cross-linking mechanism where fibromodulin binds to a specific part of the collagen domain and also forms a complex with lysyl oxidase, targeting the enzyme toward specific cross-linking sites. PMID:26893379

  9. Amyloid-β peptide binds to cytochrome C oxidase subunit 1.

    PubMed

    Hernandez-Zimbron, Luis Fernando; Luna-Muñoz, Jose; Mena, Raul; Vazquez-Ramirez, Ricardo; Kubli-Garfias, Carlos; Cribbs, David H; Manoutcharian, Karen; Gevorkian, Goar

    2012-01-01

    Extracellular and intraneuronal accumulation of amyloid-beta aggregates has been demonstrated to be involved in the pathogenesis of Alzheimer's disease (AD). However, the precise mechanism of amyloid-beta neurotoxicity is not completely understood. Previous studies suggest that binding of amyloid-beta to a number of macromolecules has deleterious effects on cellular functions. Mitochondria were found to be the target for amyloid-beta, and mitochondrial dysfunction is well documented in AD. In the present study we have shown for the first time that Aβ 1-42 bound to a peptide comprising the amino-terminal region of cytochrome c oxidase subunit 1. Phage clone, selected after screening of a human brain cDNA library expressed on M13 phage and bearing a 61 amino acid fragment of cytochrome c oxidase subunit 1, bound to Aβ 1-42 in ELISA as well as to Aβ aggregates present in AD brain. Aβ 1-42 and cytochrome c oxidase subunit 1 co-immunoprecipitated from mitochondrial fraction of differentiated human neuroblastoma cells. Likewise, molecular dynamics simulation of the cytochrome c oxidase subunit 1 and the Aβ 1-42 peptide complex resulted in a reliable helix-helix interaction, supporting the experimental results. The interaction between Aβ 1-42 and cytochrome c oxidase subunit 1 may explain, in part, the diminished enzymatic activity of respiratory chain complex IV and subsequent neuronal metabolic dysfunction observed in AD.

  10. Three-dimensional organization of three-domain copper oxidases: A review

    SciTech Connect

    Zhukhlistova, N. E. Zhukova, Yu. N.; Lyashenko, A. V.; Zaitsev, V. N.; Mikhailov, A. M.

    2008-01-15

    'Blue' copper-containing proteins are multidomain proteins that utilize a unique redox property of copper ions. Among other blue multicopper oxidases, three-domain oxidases belong to the group of proteins that exhibit a wide variety of compositions in amino acid sequences, functions, and occurrences in organisms. This paper presents a review of the data obtained from X-ray diffraction investigations of the three-dimensional structures of three-domain multicopper oxidases, such as the ascorbate oxidase catalyzing oxidation of ascorbate to dehydroascorbate and its three derivatives; the multicopper oxidase CueO (the laccase homologue); the laccases isolated from the basidiomycetes Coprinus cinereus, Trametes versicolor, Coriolus zonatus, Cerrena maxima, and Rigidoporus lignosus and the ascomycete Melanocarpus albomyces; and the bacterial laccases CotA from the endospore coats of Bacillus subtilis. A comparison of the molecular structures of the laccases of different origins demonstrates that, structurally, these objects are highly conservative. This obviously indicates that the catalytic activity of the enzymes under consideration is characterized by similar mechanisms.

  11. Fibromodulin Interacts with Collagen Cross-linking Sites and Activates Lysyl Oxidase.

    PubMed

    Kalamajski, Sebastian; Bihan, Dominique; Bonna, Arkadiusz; Rubin, Kristofer; Farndale, Richard W

    2016-04-08

    The hallmark of fibrotic disorders is a highly cross-linked and dense collagen matrix, a property driven by the oxidative action of lysyl oxidase. Other fibrosis-associated proteins also contribute to the final collagen matrix properties, one of which is fibromodulin. Its interactions with collagen affect collagen cross-linking, packing, and fibril diameter. We investigated the possibility that a specific relationship exists between fibromodulin and lysyl oxidase, potentially imparting a specific collagen matrix phenotype. We mapped the fibromodulin-collagen interaction sites using the collagen II and III Toolkit peptide libraries. Fibromodulin interacted with the peptides containing the known collagen cross-linking sites and the MMP-1 cleavage site in collagens I and II. Interestingly, the interaction sites are closely aligned within the quarter-staggered collagen fibril, suggesting a multivalent interaction between fibromodulin and several collagen helices. Furthermore, we detected an interaction between fibromodulin and lysyl oxidase (a major collagen cross-linking enzyme) and mapped the interaction site to 12 N-terminal amino acids on fibromodulin. This interaction also increases the activity of lysyl oxidase. Together, the data suggest a fibromodulin-modulated collagen cross-linking mechanism where fibromodulin binds to a specific part of the collagen domain and also forms a complex with lysyl oxidase, targeting the enzyme toward specific cross-linking sites.

  12. Amyloid-β Peptide Binds to Cytochrome C Oxidase Subunit 1

    PubMed Central

    Hernandez-Zimbron, Luis Fernando; Luna-Muñoz, Jose; Mena, Raul; Vazquez-Ramirez, Ricardo; Kubli-Garfias, Carlos; Cribbs, David H.; Manoutcharian, Karen; Gevorkian, Goar

    2012-01-01

    Extracellular and intraneuronal accumulation of amyloid-beta aggregates has been demonstrated to be involved in the pathogenesis of Alzheimer's disease (AD). However, the precise mechanism of amyloid-beta neurotoxicity is not completely understood. Previous studies suggest that binding of amyloid-beta to a number of macromolecules has deleterious effects on cellular functions. Mitochondria were found to be the target for amyloid-beta, and mitochondrial dysfunction is well documented in AD. In the present study we have shown for the first time that Aβ 1–42 bound to a peptide comprising the amino-terminal region of cytochrome c oxidase subunit 1. Phage clone, selected after screening of a human brain cDNA library expressed on M13 phage and bearing a 61 amino acid fragment of cytochrome c oxidase subunit 1, bound to Aβ 1–42 in ELISA as well as to Aβ aggregates present in AD brain. Aβ 1–42 and cytochrome c oxidase subunit 1 co-immunoprecipitated from mitochondrial fraction of differentiated human neuroblastoma cells. Likewise, molecular dynamics simulation of the cytochrome c oxidase subunit 1 and the Aβ 1–42 peptide complex resulted in a reliable helix-helix interaction, supporting the experimental results. The interaction between Aβ 1–42 and cytochrome c oxidase subunit 1 may explain, in part, the diminished enzymatic activity of respiratory chain complex IV and subsequent neuronal metabolic dysfunction observed in AD. PMID:22927926

  13. Effects of xanthine oxidase inhibitors on renal function and blood pressure in hypertensive patients with hyperuricemia.

    PubMed

    Kohagura, Kentaro; Tana, Takeshi; Higa, Akira; Yamazato, Masanobu; Ishida, Akio; Nagahama, Kazufumi; Sakima, Atsushi; Iseki, Kunitoshi; Ohya, Yusuke

    2016-08-01

    Hyperuricemia may promote the progression of hypertension and renal dysfunction. However, the effects of hyperuricemia treatment on blood pressure and renal function in adult hypertensive patients with hyperuricemia remain unclear. A total of 137 hypertensive patients with hyperuricemia (96 men and 41 women; mean age of 67 years) who recently started taking xanthine oxidase inhibitors (allopurinol or febuxostat) as outpatients were recruited. Serum uric acid level, estimated glomerular filtration rate (eGFR, ml min(-1) per 1.73 m(2)) and blood pressure (mm Hg) were retrospectively compared immediately before and shortly after starting treatment with xanthine oxidase inhibitors. The mean blood pressure and the eGFR immediately before starting treatment were 128/71 mm Hg and 44.6 ml min(-1) per 1.73 m(2), respectively. Although the eGFR decreased from 46.6 to 44.6 ml min(-1) per 1.73 m(2) before starting treatment with xanthine oxidase inhibitors, it increased to 46.2 ml min(-1) per 1.73 m(2) (P=0.001, compared with immediately before treatment) without any significant changes in blood pressure after the administration of xanthine oxidase inhibitors. Multiple regression analysis revealed that the increase in eGFR after starting xanthine oxidase inhibitor treatment positively correlated with the changes in systolic blood pressure and negatively correlated with the changes in uric acid levels and the use of renin-angiotensin system inhibitors. These results suggest that xanthine oxidase inhibitors may delay the progression of renal dysfunction in adult hypertensive patients with hyperuricemia.

  14. Current status of human hookworm infections, ascariasis, trichuriasis, schistosomiasis mekongi and other trematodiases in Lao People's Democratic Republic.

    PubMed

    Laymanivong, Sakhone; Hangvanthong, Bouasy; Keokhamphavanh, Boualy; Phommasansak, Manisak; Phinmaland, Baunphone; Sanpool, Oranuch; Maleewong, Wanchai; Intapan, Pewpan M

    2014-04-01

    Soil-transmitted helminth (STH) infections, and schistosomiasis and other trematodiases often have a high prevalence in developing countries. Here, we present updated information on the prevalence of these parasites in the Lao People's Democratic Republic (Lao PDR) in 2012, arising from the annual national helminthiasis survey. Fecal specimens were collected from 8,610 inhabitants of 12 provinces and one municipality (Bokeo, Houaphan, Luang Namtha, Luang Prabang, Oudomxay, and Phongsaly Provinces from northern Lao PDR; Bolikhamxay and Xieng Khouang Provinces and Vientiane Municipality from the central part of the country; and Attapeu, Champasak, Saravan, and Sekong Provinces from southern Lao PDR). The overall prevalence of three major STHs, Ascaris lumbricoides, Trichuris trichiura, and hookworms (Necator americanus and Ancylostoma duodenale) were 11.6%, 8.5%, and 25.0%, respectively. Prevalence of Schistosoma mekongi infection was 0.1%, and of miscellaneous trematodiases (including opisthorchiasis) was 14.0%. Clearly, the nationwide parasite control project is still necessary to reduce morbidity caused by helminthic diseases.

  15. The Pastoral Care and Challenges of the People from Cambodia, Laos and Vietnam in the United States.

    ERIC Educational Resources Information Center

    Tran, Peter

    1990-01-01

    Discusses responses of the Catholic church to the special needs of Indochinese refugees in the United States. Reviews the influence of Catholicism in Cambodia, Laos, and Vietnam, and describes activities of itinerant ministries to Catholic refugee communities across the U.S. The church's mission must be openness and hospitality toward newcomers.…

  16. Understanding School Health Environment through Interviews with Key Stakeholders in Lao PDR, Mongolia, Nepal and Sri Lanka

    ERIC Educational Resources Information Center

    Park, Sohyun; Lee, Eun Young; Gittelsohn, Joel; Nkala, Denis; Choi, Bo Youl

    2015-01-01

    Studies on health promoting schools (HPS) in low- and middle-income countries (LMICs) are scarce. To contribute to the development of HPS in these countries, we conducted formative research to understand the school environment in Lao PDR, Mongolia, Nepal, and Sri Lanka. Forty-three teachers, 10 government workers and 5 parents participated in…

  17. On the Use of Two Versions of the Force Concept Inventory to Test Conceptual Understanding of Mechanics in Lao PDR

    ERIC Educational Resources Information Center

    Luangrath, Phimpho; Pettersson, Sune; Benckert, Sylvia

    2011-01-01

    In this study, we investigated why Laotian students had a low score, when they were tested by the Force Concept Inventory (FCI). About 400 first year university students answered the FCI or a Lao version of the FCI (LFCI) with the contexts of some questions changed. The students answered a questionnaire and 34 of the students were interviewed. The…

  18. Antiviral Drug–Resistant Influenza B Viruses Carrying H134N Substitution in Neuraminidase, Laos, February 2016

    PubMed Central

    Baranovich, Tatiana; Vongphrachanh, Phengta; Ketmayoon, Pakapak; Sisouk, Thongchanh; Chomlasack, Khampheng; Khanthamaly, Viengphone; Nguyen, Ha Thuy; Mishin, Vasiliy P.; Marjuki, Henju; Barnes, John R.; Garten, Rebecca J.; Stevens, James; Wentworth, David E.

    2017-01-01

    In February 2016, three influenza B/Victoria/2/87 lineage viruses exhibiting 4- to 158-fold reduced inhibition by neuraminidase inhibitors were detected in Laos. These viruses had an H134N substitution in the neuraminidase and replicated efficiently in vitro and in ferrets. Current antiviral drugs may be ineffective in controlling infections caused by viruses harboring this mutation. PMID:28322707

  19. Predicting environmental suitability for a rare and threatened species (Lao newt, Laotriton laoensis) using validated species distribution models.

    PubMed

    Chunco, Amanda J; Phimmachak, Somphouthone; Sivongxay, Niane; Stuart, Bryan L

    2013-01-01

    The Lao newt (Laotriton laoensis) is a recently described species currently known only from northern Laos. Little is known about the species, but it is threatened as a result of overharvesting. We integrated field survey results with climate and altitude data to predict the geographic distribution of this species using the niche modeling program Maxent, and we validated these predictions by using interviews with local residents to confirm model predictions of presence and absence. The results of the validated Maxent models were then used to characterize the environmental conditions of areas predicted suitable for L. laoensis. Finally, we overlaid the resulting model with a map of current national protected areas in Laos to determine whether or not any land predicted to be suitable for this species is coincident with a national protected area. We found that both area under the curve (AUC) values and interview data provided strong support for the predictive power of these models, and we suggest that interview data could be used more widely in species distribution niche modeling. Our results further indicated that this species is mostly likely geographically restricted to high altitude regions (i.e., over 1,000 m elevation) in northern Laos and that only a minute fraction of suitable habitat is currently protected. This work thus emphasizes that increased protection efforts, including listing this species as endangered and the establishment of protected areas in the region predicted to be suitable for L. laoensis, are urgently needed.

  20. Red clover polyphenol oxidase and lipid metabolism.

    PubMed

    Van Ranst, G; Lee, M R F; Fievez, V

    2011-02-01

    Increasing the polyunsaturated fatty acid (PUFA) composition of milk is acknowledged to be of benefit to consumer health. Despite the high PUFA content of forages, milk fat contains only about 3% of PUFA and only about 0.5% of n-3 fatty acids. This is mainly due to intensive lipid metabolism in the rumen (lipolysis and biohydrogenation) and during conservation (lipolysis and oxidation) such as drying (hay) and ensiling (silage). In red clover, polyphenol oxidase (PPO) has been suggested to protect lipids against degradation, both in the silage as well as in the rumen, leading to a higher output of PUFA in ruminant products (meat and milk). PPO mediates the oxidation of phenols and diphenols to quinones, which will readily react with nucleophilic binding sites. Such binding sites can be found on proteins, resulting in the formation of protein-bound phenols. This review summarizes the different methods that have been used to assess PPO activity in red clover, and an overview on the current understanding of PPO activity and activation in red clover. Knowledge on these aspects is of major importance to fully harness PPO's lipid-protecting role. Furthermore, we review the studies that evidence PPO-mediated lipid protection and discuss its possible importance in lab-scale silages and further in an in vitro rumen system. It is demonstrated that high (induction of) PPO activity can lead to lower lipolysis in the silage and lower biohydrogenation in the rumen. There are three hypotheses on its working mechanism: (i) protein-bound phenols could directly bind to enzymes (e.g. lipases) as such inhibiting them; (ii) binding of quinones in and between proteins embedded in a lipid membrane (e.g. in the chloroplast) could lead to encapsulation of the lipids; (iii) direct binding of quinones to nucleophilic sites in polar lipids also could lead to protection. There is no exclusive evidence on which mechanism is most important, although there are strong indications that only lipid

  1. Oxidation of the flavonol fisetin by polyphenol oxidase.

    PubMed

    Jiménez, M; Escribano-Cebrián, J; García-Carmona, F

    1998-11-27

    The present study demonstrates the antiradical efficiency of fisetin, a flavonol widely distributed in fruits and vegetables, by its ability to react with two different free radicals, ABTS; and DPPH;. The polyphenolic nature of fisetin led us to consider whether it might be oxidised by polyphenol oxidase (PPO), and the results reported show that it can be oxidised by PPO extracted and partially purified from broad bean seeds. The reaction was followed by recording spectral changes with time, with maximal spectral changes being observed at 282 nm (increase in absorbance) and at 362 nm (decrease). The presence of two isosbectic points (at 265 and 304 nm) suggested that only one absorbent product was formed. These spectral changes were not observed in the absence of PPO. The oxidation rate varied with the pH, reaching its highest value at pH 5.5. The fisetin oxidation rate increased in the presence of sodium dodecyl sulfate, an activator of polyphenol oxidase. Maximal activity was obtained at 0.87 mM sodium dodecyl sulfate. The following kinetic parameters were determined: Vmax=49 microM/min, Km=0.6 mM, Vmax/Km=8.2x10-2 min-1. Flavonol oxidation was inhibited by selective PPO inhibitors such as cinnamic acid (a classical competitive inhibitor, Ki=1.4 mM) and 4-hexylresorcinol, which behaved as a slow-binding inhibitor. The results reported show that fisetin oxidation was strictly dependent on the presence of polyphenol oxidase.

  2. Effect of naphthalene on cytochrome oxidase activity

    SciTech Connect

    Harmon, H.J.

    1988-01-01

    Previous reports have demonstrated that naphthalene inhibits oxygen consumption in Daphnia magna tissue culture cells, and intact mitochondria and submitochondrial particles. These studies were extended to algal mitochondrial respiration as well as photosynthetic activity. The authors were able to demonstrate the specific site of apparent respiratory inhibition to be coenzyme Q (ubiquinone, UQ) and later to demonstrate the molecular basis of this inhibition at ubiquinone. The authors previously could not demonstrate an effect of naphthalene on cytochrome oxidase activity. However, the observation that naphthalene can stimulate respiration in algae prompted the reinvestigation of the effect of naphthalene on the kinetics of cytochrome oxidase. Cytochrome oxidase is a multi-subunit membranous protein responsible for the oxidation of cytochrome c and the reduction of molecular oxygen to water. Because of the complicated nature and mechanism of this enzyme, the potential exists for multiple and possibly opposite effects of naphthalene on its function.

  3. Micromapping of thalassemia and hemoglobinopathies in diferent regions of northeast Thailand and Vientiane, Laos People's Democratic Republic.

    PubMed

    Tritipsombut, Jaruwan; Sanchaisuriya, Kanokwan; Phollarp, Prachatip; Bouakhasith, Dalouny; Sanchaisuriya, Pattara; Fucharoen, Goonnapa; Fucharoen, Supan; Schelp, Frank P

    2012-01-01

    In order to determine the prevalence of thalassemia and hemoglobinopathies in different regions of northeast (NE) Thailand and Vientiane, Laos People's Democratic Republic (PDR), a total of 1,809 blood samples were collected consecutively from individuals attending antenatal care services at 11 community hospitals in different regions of NE Thailand and three hospitals in Vientiane, Laos PDR, from May 2009 to April 2010. All individuals were investigated for thalassemia and hemoglobinopathies using standard methods. For individuals from NE Thailand, the carrier frequencies were 41.7% for Hb E [β26(B8)Glu→Lys, GAG>AAG], 5.8% for α(0)-thalassemia (α(0)-thal), and 0.9% for β-thal. The THAI deletion type of α(0)-thal was found in one individual from an ethnic minority. From a group of pregnant Laotian women, 30.1% were Hb E carriers. The prevalence of α(0)-thal of 8.6% for the Laotian women was similar to that found in the upper northeastern part of Thailand. The frequency of β-thal was 2.3 %. The proportion of carriers of α(+)-thal and Hb Constant Spring (Hb CS, α142, Term→Gln (TAA>CAA in α2)] ) from Thailand and Laos was significantly different. The frequency of Hb Paksé [α142, Term→Tyr (TAA>TAT in α2)] was relatively low for Thailand as well as for Laos. The results indicate that thalassemia and hemoglobinopathies are a significant health burden in the region and that a prevention and control program for severe thalassemia diseases should be established in Laos.

  4. An ethnobotanical survey of medicinal plants of Laos toward the discovery of bioactive compounds as potential candidates for pharmaceutical development

    PubMed Central

    Soejarto, D.D.; Gyllenhaal, C.; Kadushin, M.R.; Southavong, B.; Sydara, K.; Bouamanivong, S.; Xaiveu, M.; Zhang, H.-J.; Franzblau, S.G.; Tan, Ghee T.; Pezzuto, J.M.; Riley, M.C.; Elkington, B.G.; Waller, D.P.

    2012-01-01

    Context An ethnobotany-based approach in the selection of raw plant materials to study was implemented. Objective To acquire raw plant materials using ethnobotanical field interviews as starting point to discover new bioactive compounds from medicinal plants of the Lao People’s Democratic Republic. Methods Using semi-structured field interviews with healers in the Lao PDR, plant samples were collected, extracted, and bio-assayed to detect bioactivity against cancer, HIV/AIDS, TB, malaria. Plant species demonstrating activity were recollected and the extracts subjected to a bioassay-guided isolation protocol to isolate and identify the active compounds. Results Field interviews with 118 healers in 15 of 17 provinces of Lao PDR yielded 753 collections (573 species) with 955 plant samples. Of these 955, 50 extracts demonstrated activity in the anticancer, 10 in the anti-HIV, 30 in the anti-TB, and 52 in the antimalarial assay. Recollection of actives followed by bioassay-guided isolation processes yielded a series of new and known in vitro-active anticancer and antimalarial compounds from 5 species. Discussion Laos has a rich biodiversity, harboring an estimated 8000–11,000 species of plants. In a country highly dependent on traditional medicine for its primary health care, this rich plant diversity serves as a major source of their medication. Conclusions Ethnobotanical survey has demonstrated the richness of plant-based traditional medicine of Lao PDR, taxonomically and therapeutically. Biological assays of extracts of half of the 955 samples followed by in-depth studies of a number of actives have yielded a series of new bioactive compounds against the diseases of cancer and malaria. PMID:22136442

  5. The CYP701B1 of Physcomitrella patens is an ent-kaurene oxidase that resists inhibition by uniconazole-P.

    PubMed

    Miyazaki, Sho; Katsumata, Takumi; Natsume, Masahiro; Kawaide, Hiroshi

    2011-06-23

    The moss Physcomitrella patens produces both ent-kaurene and ent-kaurenoic acid, which are intermediates of gibberellin biosynthesis in flowering plants. The CYP701 superfamily of cytochrome P450s functions as ent-kaurene oxidases in the biosynthesis of ent-kaurenoic acid. A candidate gene encoding ent-kaurene oxidase in P. patens, CYP701B1, was cloned and heterologously expressed in yeast to examine enzyme activities in vitro. The recombinant CYP701B1 protein catalyzed the oxidation reaction from ent-kaurene to ent-kaurenoic acid. CYP701B1 activity was highly resistant to the ent-kaurene oxidase inhibitor uniconazole-P (IC(50) 64 μM), even though the activity of Arabidopsis ent-kaurene oxidase (CYP701A3) was sensitive (IC(50) 0.26 μM).

  6. Stereospecific dehydrogenation of (25R)- and (25S)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acids by acyl-CoA oxidase in rat liver light mitochondrial fraction.

    PubMed

    Ikegawa, S; Watanabe, H; Goto, T; Mano, N; Goto, J; Nambara, T

    1995-08-01

    From a stereochemical point of view, the dehydrogenation mechanism of the biotransformation of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid (THCA) into (24E)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholest-24-enoic acid (delta 24-THCA) has been studied with capillary gas chromatography (GC)/negative ion chemical ionization (NICI)-mass spectrometry. After incubation of (24R,25R)- or (24S,25S)-[24,25-2H2]THCA, synthesized from (24E)-delta 24-THCA by a deuterated diimide reduction, with a rat liver light mitochondrial fraction, 5 beta-cholestanoic acids were extracted and derivatized into a pentafluorobenzyl (PFB) ester-dimethylethylsilyl (DMES) ether. Subsequent resolution into THCA and delta 24-THCA was attained by GC on a cross-linked 5% phenylmethyl silicone fused-silica capillary column monitored with a corresponding characteristic carboxylate anion [M-PFB]- in the NICI mode. The stereospecific elimination of a pro-R hydrogen at C-24 in both (25R)- and (25S)-THCA indicated syn-elimination for the former, whereas anti-elimination for the latter was observed.

  7. The Promotion of Indole-3-acetic Acid Oxidation in Pea Buds by Gibberellic Acid and Treatment 1

    PubMed Central

    Ockerse, Ralph; Waber, Jack

    1970-01-01

    Terminal buds of dark-grown pea (Pisum sativum) seedlings have an indole-3-acetic acid oxidase which does not require Mn2+ and 2,4-dichlorophenol as cofactors. Oxidase activity is at least 50 times higher in buds of tall peas than in dwarf seedlings. Administration of gibberellic acid to dwarf peas stimulates both growth and indoleacetic acid oxidase activity to the same levels as in tall seedlings. By contrast, indoleacetic acid oxidation assayed in the presence of Mn2+ and 2,4-dichlorophenol proceeds at similar rates regardless of gibberellin application. Treatment of tall peas with the growth retardant AMO-1618 reduces growth and oxidase activity. Such treated seedlings are indistinguishably dwarf. The enzyme does not appear to be polyphenol oxidase, nor do the results suggest that reduced activity in dwarf buds is due to higher levels of a dialyzable inhibitor. The peroxidative nature of the oxidase is probable. PMID:5500209

  8. Sequence analysis of the oxidase/reductase genes upstream of the Rhodococcus erythropolis aldehyde dehydrogenase gene thcA reveals a gene organisation different from Mycobacterium tuberculosis.

    PubMed

    Nagy, I; De Mot, R

    1999-01-01

    The sequence of the DNA region upstream of the thiocarbamate-inducible aldehyde dehydrogenase gene thcA of Rhodococcus erythropolis NI86/21 was determined. Most of the predicted ORFs are related to various oxidases/reductases, including short-chain oxidases/reductases, GMC oxidoreductases, alpha-hydroxy acid oxidases (subfamily 1 flavin oxidases/dehydrogenases), and subfamily 2 flavin oxidases/dehydrogenases. One ORF is related to enzymes involved in biosynthesis of PQQ or molybdopterin cofactors. In addition, a putative member of the TetR family of regulatory proteins was identified. The substantial sequence divergence from functionally characterized enzymes precludes a reliable prediction about the probable function of these proteins at this stage. In Mycobacterium tuberculosis H37Rv, most of these ORFs have homologs that are also clustered in the genome, but some striking differences in gene organization were observed between Rhodococcus and Mycobacterium.

  9. Financial Impacts of Foot-and-Mouth Disease at Village and National Levels in Lao PDR.

    PubMed

    Nampanya, S; Khounsy, S; Abila, R; Young, J R; Bush, R D; Windsor, P A

    2016-10-01

    To assist policies on Foot-and-Mouth Disease (FMD) control in Laos and the Mekong region, the financial impact of recent outbreaks at village and national levels was examined. Village-level impacts were derived from recent research on financial losses due to FMD per smallholder household and number of households with FMD-affected livestock in the village. National-level impacts of FMD were determined from examination of 2011-2013 FMD reported to the Lao Department of Livestock and Fisheries (DLF), with the 2011 epidemic reported separately due to the large number and size of outbreaks of FMD in that year. Estimates of the national financial impact of FMD were based on (i) total FMD financial losses at the village level and (ii) the costs of FMD responses and other related costs at the DLF, provincial and district levels where FMD was reported, but excluding the costs of revenue forgone. A Monte Carlo simulation was utilized to account for likelihood of FMD over- and under-reporting. Foot-and-mouth disease was recorded in four provinces of Phonsaly, Bokeo, Xayyabouli and Champasak in three consecutive years from 2011 to 2013. However, the FMD epidemic in 2011 was more widely distributed and involved 414 villages in 14 provinces, with thousands of cases of morbidity in cattle and buffalo and some mortalities. The estimated financial losses due to FMD in 2011 were USD 30 881(±23 176) at the village level and USD 13 512 291 at the national level based on the number of villages with FMD outbreaks reported. However, when the likelihood of FMD under-reporting was accounted for, the estimated financial losses at the national level could potentially increase to USD 102 094 464 (±52 147 261), being almost 12% of the estimated farm gate value of the national large ruminant herd. These findings confirm that FMD causes substantial financial impacts in villages and to the national economy of Laos, providing justification for sustained investments in FMD control

  10. The GA5 locus of Arabidopsis thaliana encodes a multifunctional gibberellin 20-oxidase: Molecular cloning and functional expression

    SciTech Connect

    Xu, Yun-Ling; Li, Li; Wu, Keqiang

    1995-07-03

    The biosynthesis of gibberellins (GAs) after GA{sub 12}-aldehyde involves a series of oxidative steps that lead to the formation of bioactive GAs. Previously, a cDNA clone encoding a GA 20-oxidase [gibberellin, 2-oxoglutarate:oxygen oxidoreductase (20-hydroxylating, oxidizing), EC 1.14.11-] was isolated by immunoscreening a cDNA library from liquid endosperm of pumpkin (Cucurbita maxima L.) with antibodies against partially purified GA 20-oxidase. Here, we report isolation of a genomic clone for GA 20-oxidase from a genomic library of the long-day species Arabidopsis thaliana Heynh., strain Columbia, by using the pumpkin cDNA clone as a heterologous probe. This genomic clone contains a GA 20-oxidase gene that consists of three exons and two introns. The three exons are 1131-bp long and encode 377 amino acid residues. A cDNA clone corresponding to the putative GA 20-oxidase genomic sequence was constructed with the reverse transcription-PCR method, and the identity of the cDNA clone was confirmed by analyzing the capability of the fusion protein expressed in Escherichia coli to convert GA{sub 53} to GA{sub 44} and GA{sub 19} to GA{sub 20}. The Arabidopsis GA 20-oxidase shares 55% identity and >80% similarity with the pumpkin GA 20-oxidase at the derived amino acid level. Both GA 20-oxidases share high homology with other 2-oxoglutarate-dependent dioxygenases (2-ODDs), but the highest homology was found between the two GA 20-oxidases. Mapping results indicated tight linkage between the cloned GA 20-oxidase and the GA locus of Arabidopsis. The ga5 semidwarf mutant contains a G {yields} A point mutation that inserts a translational stop codon in the protein-coding sequence, thus confirming that the GA5 locus encodes GA 20-oxidase. Expression of the GA5 gene in Arabidopsis leaves was enhanced after plants were transferred from short to long days; it was reduced by GA{sub 4} treatment, suggesting end-product repression in the GA biosynthetic pathway. 28 refs., 6 figs.

  11. Purification of the Alpha Glycerophosphate Oxidase From Trypanosomes.

    DTIC Science & Technology

    1992-08-01

    is the purifica- tion of the glycerphosphate oxidase from the terminal oxidase in bloodstream trypanosomes. African trypanosomiasis remains one of the...oxidase from the terminal oxidase in bloodstream trypanosomes. African trypanosomiasis remains one of the major diseases in the world today, affecting...interest as a possible target for drug chemotherapy . At present only suramin and organic arsenicals remain as the mainstay of chemotherapy , despite their

  12. Titanium Dioxide Nanoparticles Increase Superoxide Anion Production by Acting on NADPH Oxidase.

    PubMed

    Masoud, Rawand; Bizouarn, Tania; Trepout, Sylvain; Wien, Frank; Baciou, Laura; Marco, Sergio; Houée Levin, Chantal

    2015-01-01

    Titanium dioxide (TiO2) anatase nanoparticles (NPs) are metal oxide NPs commercialized for several uses of everyday life. However their toxicity has been poorly investigated. Cellular internalization of NPs has been shown to activate macrophages and neutrophils that contribute to superoxide anion production by the NADPH oxidase complex. Transmission electron micrososcopy images showed that the membrane fractions were close to the NPs while fluorescence indicated an interaction between NPs and cytosolic proteins. Using a cell-free system, we have investigated the influence of TiO2 NPs on the behavior of the NADPH oxidase. In the absence of the classical activator molecules of the enzyme (arachidonic acid) but in the presence of TiO2 NPs, no production of superoxide ions could be detected indicating that TiO2 NPs were unable to activate by themselves the complex. However once the NADPH oxidase was activated (i.e., by arachidonic acid), the rate of superoxide anion production went up to 140% of its value without NPs, this effect being dependent on their concentration. In the presence of TiO2 nanoparticles, the NADPH oxidase produces more superoxide ions, hence induces higher oxidative stress. This hyper-activation and the subsequent increase in ROS production by TiO2 NPs could participate to the oxidative stress development.

  13. Crystal Structure of the Deglycating Enzyme Fructosamine Oxidase (Amadoriase ll)

    SciTech Connect

    Collard, F.; Zhang, J; Nemet, I; Qanungo, K; Monnier, V; Yee, V

    2008-01-01

    Fructosamine oxidases (FAOX) catalyze the oxidative deglycation of low molecular weight fructosamines (Amadori products). These proteins are of interest in developing an enzyme to deglycate proteins implicated in diabetic complications. We report here the crystal structures of FAOX-II from the fungi Aspergillus fumigatus, in free form and in complex with the inhibitor fructosyl-thioacetate, at 1.75 and 1.6{angstrom} resolution, respectively. FAOX-II is a two domain FAD-enzyme with an overall topology that is most similar to that of monomeric sarcosine oxidase. Active site residues Tyr-60, Arg-112 and Lys-368 bind the carboxylic portion of the fructosamine, whereas Glu-280 and Arg-411 bind the fructosyl portion. From structure-guided sequence comparison, Glu-280 was identified as a signature residue for FAOX activity. Two flexible surface loops become ordered upon binding of the inhibitor in a catalytic site that is about 12{angstrom} deep, providing an explanation for the very low activity of FAOX enzymes toward protein-bound fructosamines, which would have difficulty accessing the active site. Structure-based mutagenesis showed that substitution of Glu-280 and Arg-411 eliminates enzyme activity. In contrast, modification of other active site residues or of amino acids in the flexible active site loops has little effect, highlighting these regions as potential targets in designing an enzyme that will accept larger substrates.

  14. Crystal Structure of the Deglycating Enzyme Fructosamine Oxidase (Amadoriase II)

    SciTech Connect

    Collard, François; Zhang, Jianye; Nemet, Ina; Qanungo, Kaustubha R.; Monnier, Vincent M.; Yee, Vivien C.

    2009-01-12

    Fructosamine oxidases (FAOX) catalyze the oxidative deglycation of low molecular weight fructosamines (Amadori products). These proteins are of interest in developing an enzyme to deglycate proteins implicated in diabetic complications. We report here the crystal structures of FAOX-II from the fungi Aspergillus fumigatus, in free form and in complex with the inhibitor fructosyl-thioacetate, at 1.75 and 1.6{angstrom} resolution, respectively. FAOX-II is a two domain FAD-enzyme with an overall topology that is most similar to that of monomeric sarcosine oxidase. Active site residues Tyr-60, Arg-112 and Lys-368 bind the carboxylic portion of the fructosamine, whereas Glu-280 and Arg-411 bind the fructosyl portion. From structure-guided sequence comparison, Glu-280 was identified as a signature residue for FAOX activity. Two flexible surface loops become ordered upon binding of the inhibitor in a catalytic site that is about 12{angstrom} deep, providing an explanation for the very low activity of FAOX enzymes toward protein-bound fructosamines, which would have difficulty accessing the active site. Structure-based mutagenesis showed that substitution of Glu-280 and Arg-411 eliminates enzyme activity. In contrast, modification of other active site residues or of amino acids in the flexible active site loops has little effect, highlighting these regions as potential targets in designing an enzyme that will accept larger substrates.

  15. Alternative oxidase in animals: unique characteristics and taxonomic distribution.

    PubMed

    McDonald, Allison E; Vanlerberghe, Greg C; Staples, James F

    2009-08-01

    Alternative oxidase (AOX), a ubiquinol oxidase, introduces a branch point into the respiratory electron transport chain, bypassing complexes III and IV and resulting in cyanide-resistant respiration. Previously, AOX was thought to be limited to plants and some fungi and protists but recent work has demonstrated the presence of AOX in most kingdoms of life, including animals. In the present study we identified AOX in 28 animal species representing nine phyla. This expands the known taxonomic distribution of AOX in animals by 10 species and two phyla. Using bioinformatics we found AOX gene sequences in members of the animal phyla Porifera, Placozoa, Cnidaria, Mollusca, Annelida, Nematoda, Echinodermata, Hemichordata and Chordata. Using reverse-transcriptase polymerase chain reaction (RT-PCR) with degenerate primers designed to recognize conserved regions of animal AOX, we demonstrated that AOX genes are transcribed in several animals from different phyla. An analysis of full-length AOX sequences revealed an amino acid motif in the C-terminal region of the protein that is unique to animal AOXs. Animal AOX also lacks an N-terminal cysteine residue that is known to be important for AOX enzyme regulation in plants. We conclude that the presence of AOX is the ancestral state in animals and hypothesize that its absence in some lineages, including vertebrates, is due to gene loss events.

  16. Location and catalytic characteristics of a multipotent bacterial polyphenol oxidase.

    PubMed

    Fernández, E; Sanchez-Amat, A; Solano, F

    1999-10-01

    The melanogenic marine bacterium Marinomonas mediterranea contains a multipotent polyphenol oxidase (PPO) able to oxidize substrates characteristic for tyrosinase and laccase. Thus, this enzyme shows tyrosine hydroxylase activity and it catalyzes the oxidation of a wide variety of o-diphenol as well as o-methoxy-activated phenols. The study of its sensitivity to different inhibitors also revealed intermediate features between laccase and tyrosinase. It is similar to tyrosinases in its sensitivity to tropolone, but it resembles laccases in its resistance to cinnamic acid and phenylthiourea, and in its sensitivity to fluoride anion. This enzyme is mostly membrane-bound and can be solubilized either by non-ionic detergent or lipase treatments of the membrane. The expression of this enzymatic activity is growth-phase regulated, reaching a maximum in the stationary phase of bacterial growth, but L-tyrosine, Cu(II) ions, or 2,5-xylidine do not induce it. This enzyme can be separated from a second PPO form by gel permeation chromatography. The second PPO is located in the soluble fraction and shows a sodium dodecyl sulfate (SDS)-activated action on the characteristic substrates for tyrosinase, L-tyrosine, and L-dopa, but it does not show activity towards laccase-specific substrates. The involvement of the multipotent PPO in melanogenesis and its relationship with the SDS-activated form and with the alternative functions proposed for multicopper oxidases in other microorganisms are discussed.

  17. Crystal Structure of the Deglycating Enzyme Fructosamine Oxidase (Amadoriase II)*

    PubMed Central

    Collard, François; Zhang, Jianye; Nemet, Ina; Qanungo, Kaustubha R.; Monnier, Vincent M.; Yee, Vivien C.

    2008-01-01

    Fructosamine oxidases (FAOX) catalyze the oxidative deglycation of low molecular weight fructosamines (Amadori products). These proteins are of interest in developing an enzyme to deglycate proteins implicated in diabetic complications. We report here the crystal structures of FAOX-II from the fungi Aspergillus fumigatus, in free form and in complex with the inhibitor fructosyl-thioacetate, at 1.75 and 1.6Å resolution, respectively. FAOX-II is a two domain FAD-enzyme with an overall topology that is most similar to that of monomeric sarcosine oxidase. Active site residues Tyr-60, Arg-112 and Lys-368 bind the carboxylic portion of the fructosamine, whereas Glu-280 and Arg-411 bind the fructosyl portion. From structure-guided sequence comparison, Glu-280 was identified as a signature residue for FAOX activity. Two flexible surface loops become ordered upon binding of the inhibitor in a catalytic site that is about 12Å deep, providing an explanation for the very low activity of FAOX enzymes toward protein-bound fructosamines, which would have difficulty accessing the active site. Structure-based mutagenesis showed that substitution of Glu-280 and Arg-411 eliminates enzyme activity. In contrast, modification of other active site residues or of amino acids in the flexible active site loops has little effect, highlighting these regions as potential targets in designing an enzyme that will accept larger substrates. PMID:18667417

  18. Copro-molecular identification of infections with hookworm eggs in rural Lao PDR.

    PubMed

    Sato, Megumi; Sanguankiat, Surapol; Yoonuan, Tippayarat; Pongvongsa, Tiengkham; Keomoungkhoun, Malaythong; Phimmayoi, Inthava; Boupa, Boungnong; Moji, Kazuhiko; Waikagul, Jitra

    2010-09-01

    The prevalence of hookworm eggs in fecal samples, by modified cellophane thick-smear technique, was found to be 30.0% (61/203 samples) in Lahanam Village, Savannakhet Province, Lao PDR. The hookworm eggs were morphologically heterogeneous, so that identification was confirmed by copro-PCR with specific primers for hookworms and Trichostrongylus spp.; 12 samples were positive for Necator americanus, 19 for Ancylostoma spp., with one mixed infection of both. Sequencing of the Ancylostoma spp. copro-PCR products found A. duodenale, and also the animal hookworms, A. caninum and A. ceylanicum. Moreover, Trichostrongylus spp.-specific copro-PCR revealed a significant rate of infection (43/203; 21.2%). Sequencing confirmed the zoonotic species, T. colubriformis. PCR/sequencing is useful for differentiating parasite species. The positives by the Kato-Katz method, and by the combined hookworm/Trichostrongylus specific-PCR, were comparable, although the agreement between the two methodologies was only 50%.

  19. First reported case of elephant endotheliotropic herpes virus infection in Laos.

    PubMed

    Bouchard, Bertrand; Xaymountry, Bounmy; Thongtip, Nikorn; Lertwatcharasarakul, Preeda; Wajjwalku, Worawidh

    2014-09-01

    The elephant endotheliotropic herpesvirus (EEHV) is now recognized as one of the main causes of death of young Asian elephants (Elephas maximus) in North American zoos. Its impact in wild and domestic elephant populations in Asia is not clearly understood. This article describes the first case of EEHV infection in Lao People's Democratic Republic of a 2.5-yr-old domestic male Asian elephant. Clinical signs and pathological findings reported here are consistent with previous infections in Asian elephant calves. Phylogenetic analyses showed 100% homology with other EEHV-1A strains identified in Asia, Europe, and North America. Contamination of the molecular assays was ruled out, because the DNA polymerase sequence identified in this study differed from the positive control by two base pairs.

  20. Diagnosis of Opisthorchis viverrini Infection with Handheld Microscopy in Lao People's Democratic Republic.

    PubMed

    Bogoch, Isaac I; Sayasone, Somphou; Vonghachack, Youthanavanh; Meister, Isabel; Utzinger, Jürg; Odermatt, Peter; Andrews, Jason R; Keiser, Jennifer

    2016-01-01

    Opisthorchiasis is a neglected tropical disease, yet it is of considerable public health importance in Southeast Asia given the predilection for chronically infected persons to develop cholangiocarcinoma. We evaluated a handheld microscope for the diagnosis of Opisthorchis viverrini in a community-based setting in Lao People's Democratic Republic in comparison with conventional light microscopy. In stool samples collected from 104 individuals, handheld microscopy revealed a sensitivity of 70.6% and a specificity of 89.5% for O. viverrini infection. Pearson's correlation for quantitative fecal egg counts between the two devices was 0.98 (95% confidence interval: 0.98-0.99). With small adjustments to further increase diagnostic sensitivity, a handheld microscope may become a helpful tool to screen for O. viverrini and other helminth infections in public health settings.

  1. Corporate social responsibility: Benefits for youth in hydropower development in Laos

    NASA Astrophysics Data System (ADS)

    Sparkes, Stephen

    2014-04-01

    The role of the state as regulator combined with policies on Corporate Social Responsibility (CSR) that go beyond legal requirements to establishing programmes that promote development and good international business practice is an emerging new paradigm. In this paper, the example of a state-owned company, Statkraft A.S. of Norway, and its recent hydropower investment in central Laos illustrates how policy, implementation and follow-up can lead to benefits for local communities in the impacted area of the Theun-Hinboun Expansion Project (THXP). Programmes include both support for and improvement of existing government education programmes, employment opportunities and specific programmes for youth. They have been designed to mitigate possible negative effects of the influx of workers and rapid socio-economic change in the affected area. Young people continue to have a central role in the implementation of these programmes as peer educators under the supervision of project staff and non-governmental organisations (NGOs).

  2. The First Mammalian Aldehyde Oxidase Crystal Structure

    PubMed Central

    Coelho, Catarina; Mahro, Martin; Trincão, José; Carvalho, Alexandra T. P.; Ramos, Maria João; Terao, Mineko; Garattini, Enrico; Leimkühler, Silke; Romão, Maria João

    2012-01-01

    Aldehyde oxidases (AOXs) are homodimeric proteins belonging to the xanthine oxidase family of molybdenum-containing enzymes. Each 150-kDa monomer contains a FAD redox cofactor, two spectroscopically distinct [2Fe-2S] clusters, and a molybdenum cofactor located within the protein active site. AOXs are characterized by broad range substrate specificity, oxidizing different aldehydes and aromatic N-heterocycles. Despite increasing recognition of its role in the metabolism of drugs and xenobiotics, the physiological function of the protein is still largely unknown. We have crystallized and solved the crystal structure of mouse liver aldehyde oxidase 3 to 2.9 Å. This is the first mammalian AOX whose structure has been solved. The structure provides important insights into the protein active center and further evidence on the catalytic differences characterizing AOX and xanthine oxidoreductase. The mouse liver aldehyde oxidase 3 three-dimensional structure combined with kinetic, mutagenesis data, molecular docking, and molecular dynamics studies make a decisive contribution to understand the molecular basis of its rather broad substrate specificity. PMID:23019336

  3. An oxidase road to platelet adhesion.

    PubMed

    Krause, Diane S

    2016-03-17

    Platelet adhesion to collagen via collagen receptors is an important part of thrombosis. In this issue of Blood, Matsuura et al identify collagen receptors as previously unrecognized targets of the extracellular enzyme lysyl oxidase (LOX), the level of which is increased in myeloproliferative neoplasms (MPNs) and other conditions associated with pathological thromboses.

  4. Polyphenol oxidase activity in annual forage clovers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyphenol oxidase (PPO)-mediated phenol reactions in red clover (Trifolium pratense L.) bind forage protein and reduce proteolysis, producing beneficial effects on forage protein degradability, silage fermentation, and soil-N cycling. We evaluated PPO activity in seven previously untested annual c...

  5. A colorimetric assay for cytokinin oxidase.

    PubMed

    Libreros-Minotta, C A; Tipton, P A

    1995-11-01

    A simple and rapid colorimetric assay for cytokinin oxidase is described. The assay is based on the formation of a Schiff base between the enzymatic reaction product 3-methyl-2-butenal and p-aminophenol. The assay is effective in the submicromolar concentration range and can be used in crude plant extracts as well as in more highly purified preparations.

  6. Exploiting algal NADPH oxidase for biophotovoltaic energy.

    PubMed

    Anderson, Alexander; Laohavisit, Anuphon; Blaby, Ian K; Bombelli, Paolo; Howe, Christopher J; Merchant, Sabeeha S; Davies, Julia M; Smith, Alison G

    2016-01-01

    Photosynthetic microbes exhibit light-dependent electron export across the cell membrane, which can generate electricity in biological photovoltaic (BPV) devices. How electrons are exported remains to be determined; the identification of mechanisms would help selection or generation of photosynthetic microbes capable of enhanced electrical output. We show that plasma membrane NADPH oxidase activity is a significant component of light-dependent generation of electricity by the unicellular green alga Chlamydomonas reinhardtii. NADPH oxidases export electrons across the plasma membrane to form superoxide anion from oxygen. The C. reinhardtii mutant lacking the NADPH oxidase encoded by RBO1 is impaired in both extracellular superoxide anion production and current generation in a BPV device. Complementation with the wild-type gene restores both capacities, demonstrating the role of the enzyme in electron export. Monitoring light-dependent extracellular superoxide production with a colorimetric assay is shown to be an effective way of screening for electrogenic potential of candidate algal strains. The results show that algal NADPH oxidases are important for superoxide anion production and open avenues for optimizing the biological component of these devices.

  7. Forage polyphenol oxidase and ruminant livestock nutrition

    PubMed Central

    Lee, Michael R. F.

    2014-01-01

    Polyphenol oxidase (PPO) is predominately associated with the detrimental effect of browning fruit and vegetables, however, interest within PPO containing forage crops (crops to be fed to animals) has grown since the browning reaction was associated with reduced nitrogen (N) losses in silo and the rumen. The reduction in protein breakdown in silo of red clover (high PPO forage) increased the quality of protein, improving N-use efficiency [feed N into product N (e.g., Milk): NUE] when fed to ruminants. A further benefit of red clover silage feeding is a significant reduction in lipolysis (cleaving of glycerol-based lipid) in silo and an increase in the deposition of beneficial C18 polyunsaturated fatty acid (PUFA) in animal products, which has also been linked to PPO activity. PPOs protection of plant protein and glycerol based-PUFA in silo is related to the deactivation of plant proteases and lipases. This deactivation occurs through PPO catalyzing the conversion of diphenols to quinones which bind with cellular nucleophiles such as protein reforming a protein-bound phenol (PBP). If the protein is an enzyme (e.g., protease or lipase) the complexing denatures the enzyme. However, PPO is inactive in the anaerobic rumen and therefore any subsequent protection of plant protein and glycerol based-PUFA in the rumen must be as a result of events that occurred to the forage pre-ingestion. Reduced activity of plant proteases and lipases would have little effect on NUE and glycerol based-PUFA in the rumen due to the greater concentration of rumen microbial proteases and lipases. The mechanism for PPOs protection of plant protein in the rumen is a consequence of complexing plant protein, rather than protease deactivation per se. These complexed proteins reduce protein digestibility in the rumen and subsequently increase undegraded dietary protein flow to the small intestine. The mechanism for protecting glycerol-based PUFA has yet to be fully elucidated but may be associated

  8. Knowledge and perceptions of drug quality among drug sellers and consumers in Lao PDR.

    PubMed

    Syhakhang, Lamphone; Freudenthal, Solveig; Tomson, Göran; Wahlström, Rolf

    2004-11-01

    In most developing countries, including the Lao People's Democratic Republic (PDR), high prevalence of low quality drugs has been reported. The aim of this study was to explore knowledge and perceptions regarding drug quality among drug sellers and consumers, in Savannakhet province, Lao PDR. Quantitative and qualitative methods were used. Fifty-nine drug sellers and 278 exit customers were interviewed. Eight focus group discussions with drug sellers and community members were conducted. There was inadequate scientific drug knowledge among drug sellers. Only a few customers were aware of the existence of low quality drugs. Only one drug seller knew what constitutes a good quality drug according to the given criteria, and only two drug sellers knew the correct temperature for drug storage. Forty-four per cent had correct knowledge on drug labelling and 73% could read the expiry date. Fifty-eight per cent stated that they bought some drugs from unauthorized sources. Both drug sellers and consumers also elaborated on a local definition of drug quality. They determined drug quality by its perceived efficacy in the sense that a drug is good if it takes the disease away. They also trusted the responsible authorities not to provide them with low quality drugs. A majority of the consumers (73%) did not worry about the quality of the drugs, their greatest problem being financial constraints. People living in urban districts had significantly more knowledge on aspects of drug quality than those living in rural and remote areas. The limitations in scientific knowledge among drug sellers and the low awareness among consumers may contribute to the continued existence of low quality drugs. Government interventions through training of drug sellers and drug information for lay people are suggested.

  9. Orbital reconstruction at the LAO/STO interface investigated by x-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Ghiringhelli, G.; Moretti Sala, M.; Cezar, J. C.; Brookes, N. B.; De Luca, G. M.; Salluzzo, M.

    2010-08-01

    The appearance of high mobility electrons at the LaAlO3/SrTiO3 (LAO/STO) interface has raised strong interest in the material science community and a lively debate on the origin of the phenomenon. In particular, in view of the large band gaps of the two bulk single crystals constituting this heterostructure, the realization of a conducting system was totally unexpected. A possible explanation is an electronic reconstruction of the interface, realizing a transfer of electrons from the LaAlO3 surface to SrTiO3 near the interface, thereby avoiding the polarization catastrophe associated with the alternating polar layers of the LaAlO3 film. The predictions of theoretical models based on this idea are quite peculiar and need to be verified by specific experiments able to address the electronic properties of the LAO/STO buried interface. Here, by using x-ray spectroscopy techniques, we show that the appearance of an electron system is correlated to the removal of the degeneracy of the titanium 3d states, and doped electrons appear in a band preferentially created by the hybridization between 3dxy states of titanium and oxygen 2px,y states. This splitting is consistent with an ordering of the Ti 3dxy orbital belonging to the TiO6 octahedra close to the interface, as theoretically proposed. However, the valence of titanium ions remains prevalently 4+, therefore other mechanisms should be also considered for the stabilization of the system.

  10. Genetic diversity of coronaviruses in bats in Lao PDR and Cambodia.

    PubMed

    Lacroix, Audrey; Duong, Veasna; Hul, Vibol; San, Sorn; Davun, Hull; Omaliss, Keo; Chea, Sokha; Hassanin, Alexandre; Theppangna, Watthana; Silithammavong, Soubanh; Khammavong, Kongsy; Singhalath, Sinpakone; Greatorex, Zoe; Fine, Amanda E; Goldstein, Tracey; Olson, Sarah; Joly, Damien O; Keatts, Lucy; Dussart, Philippe; Afelt, Aneta; Frutos, Roger; Buchy, Philippe

    2017-03-01

    South-East Asia is a hot spot for emerging zoonotic diseases, and bats have been recognized as hosts for a large number of zoonotic viruses such as Severe Acute Respiratory Syndrome (SARS), responsible for acute respiratory syndrome outbreaks. Thus, it is important to expand our knowledge of the presence of viruses in bats which could represent a risk to humans. Coronaviruses (CoVs) have been reported in bat species from Thailand, China, Indonesia, Taiwan and the Philippines. However no such work was conducted in Cambodia or Lao PDR. Between 2010 and 2013, 1965 bats were therefore sampled at interfaces with human populations in these two countries. They were tested for the presence of coronavirus by consensus reverse transcription-PCR assay. A total of 93 samples (4.7%) from 17 genera of bats tested positive. Sequence analysis revealed the presence of potentially 37 and 56 coronavirus belonging to alpha-coronavirus (αCoV) and beta-CoV (βCoV), respectively. The βCoVs group is known to include some coronaviruses highly pathogenic to human, such as SARS-CoV and MERS-CoV. All coronavirus sequences generated from frugivorous bats (family Pteropodidae) (n=55) clustered with other bat βCoVs of lineage D, whereas one coronavirus from Pipistrellus coromandra fell in the lineage C of βCoVs which also includes the MERS-CoV. αCoVs were all detected in various genera of insectivorous bats and clustered with diverse bat αCoV sequences previously published. A closely related strain of PEDV, responsible for severe diarrhea in pigs (PEDV-CoV), was detected in 2 Myotis bats. We highlighted the presence and the high diversity of coronaviruses circulating in bats from Cambodia and Lao PDR. Three new bat genera and species were newly identified as host of coronaviruses, namely Macroglossus sp., Megaerops niphanae and Myotis horsfieldii.

  11. Risks, benefits and survival strategies-views from female sex workers in Savannakhet, Laos

    PubMed Central

    2012-01-01

    Background Female sex workers (FSWs) are vulnerable to sexually transmitted infections (STIs) and encounter socio-economic and health problems, including STIs/HIV, unintended pregnancy and complications from unsafe abortion, stigma, violence, and drug addiction. Reducing risks associated with sex work requires an understanding of the social and cultural context in which sex workers live and work. This study aimed to explore the working environment and perceived risks among FSWs in Savannakhet province in Laos. Methods Five focus group discussions (FGDs) and seven interviews were conducted with FSWs in Kaysone Phomvihan district in Laos. Latent content analysis was used to analyze the transcribed text. Results The results revealed that the FSWs were aware of risks but they also talked about benefits related to their work. The risks were grouped into six categories: STIs/HIV, unintended pregnancy, stigma, violence, being cheated, and social and economic insecurity. The reported benefits were financial security, fulfilling social obligations, and sexual pleasure. The FSWs reported using a number of strategies to reduce risks and increase benefits. Conclusions The desire to be self-sufficient and earn as much money as possible put the FSWs in disadvantaged and vulnerable situations. Fear of financial insecurity, obligations to support one’s family and the need to secure the future influenced FSWs’ decisions to have safe or unsafe sex. The FSWs were, however, not only victims. They also had some control over their lives and working environment, with most viewing their work as an easy and good way of earning money. PMID:23164407

  12. Inactivation of the Pseudomonas putida cytochrome o ubiquinol oxidase leads to a significant change in the transcriptome and to increased expression of the CIO and cbb3-1 terminal oxidases.

    PubMed

    Morales, Gracia; Ugidos, Ana; Rojo, Fernando

    2006-10-01

    Pseudomonas putida KT2440 contains a branched aerobic respiratory chain with several terminal oxidases. Inactivation of the cyo terminal ubiquinol oxidase has little effect on growth rate but is known to relieve the inhibition by global control that modulates induction of genes required to assimilate alkanes in cells growing in the presence of preferred carbon sources. We show that inactivation of other terminal oxidases has no effect on regulation of the alkane degradation pathway, which points to cyo as the oxidase that transmits a regulatory signal related to the activity of the electron transport chain. Using a genome-wide DNA microarray we found that inactivation of cyo has a significant effect on the transcriptome, supporting that it participates in global regulation of gene expression. Among the genes affected stand out those coding for transporters of organic acids, porins, transcriptional regulators and terminal oxidases. Real-time reverse transcription polymerase chain reaction (RT-PCR) showed that, in cells growing exponentially in a complete medium, the absence of cyo was compensated by increased expression of the cyanide-insensitive and cbb3-1 terminal oxidases, while cbb3-2 and aa3 oxidases remained unaffected. When cells enter into stationary phase cyo levels decrease and inhibition of the alkane degradation genes ceases. This was paralleled by upregulation of the cyanide-insensitive, cbb3-1, cbb3-2 and aa3 terminal oxidases. The results suggest that P. putida adapts the composition of the electron transport chain not only to optimize energy generation, but also to influence the transcriptome profile of the cell through global control of gene expression.

  13. Involvement of alternative oxidase in the regulation of sensitivity of Sclerotinia sclerotiorum to the fungicides azoxystrobin and procymidone.

    PubMed

    Xu, Ting; Wang, Ya-Ting; Liang, Wu-Sheng; Yao, Fei; Li, Yong-Hong; Li, Dian-Rong; Wang, Hao; Wang, Zheng-Yi

    2013-06-01

    Sclerotinia sclerotiorum is a filamentous fungal pathogen that can infect many economically important crops and vegetables. Alternative oxidase is the terminal oxidase of the alternative respiratory pathway in fungal mitochondria. The function of alternative oxidase was investigated in the regulation of sensitivity of S. sclerotiorum to two commercial fungicides, azoxystrobin and procymidone which have different fungitoxic mechanisms. Two isolates of S. sclerotiorum were sensitive to both fungicides. Application of salicylhydroxamic acid, a specific inhibitor of alternative oxidase, significantly increased the values of effective concentration causing 50% mycelial growth inhibition (EC50) of azoxystrobin to both S. sclerotiorum isolates, whereas notably decreased the EC50 values of procymidone. In mycelial respiration assay azoxystrobin displayed immediate inhibitory effect on cytochrome pathway capacity, but had no immediate effect on alternative pathway capacity. In contrast, procymidone showed no immediate impact on capacities of both cytochrome and alternative pathways in the mycelia. However, alternative oxidase encoding gene (aox) transcript and protein levels, alternative respiration pathway capacity of the mycelia were obviously increased by pre-treatment for 24 h with both azoxystrobin and procymidone. These results indicate that alternative oxidase was involved in the regulation of sensitivity of S. sclerotiorum to the fungicides azoxystrobin and procymidone, and that both fungicides could affect aox gene expression and the alternative respiration pathway capacity development in mycelia of this fungal pathogen.

  14. Unique targeting of cytosolic phospholipase A2 to plasma membranes mediated by the NADPH oxidase in phagocytes

    PubMed Central

    Shmelzer, Zeev; Haddad, Nurit; Admon, Ester; Pessach, Itai; Leto, Thomas L.; Eitan-Hazan, Zahit; Hershfinkel, Michal; Levy, Rachel

    2003-01-01

    Cytosolic phospholipase A2 (cPLA2)–generated arachidonic acid (AA) has been shown to be an essential requirement for the activation of NADPH oxidase, in addition to its being the major enzyme involved in the formation of eicosanoid at the nuclear membranes. The mechanism by which cPLA2 regulates NADPH oxidase activity is not known, particularly since the NADPH oxidase complex is localized in the plasma membranes of stimulated cells. The present study is the first to demonstrate that upon stimulation cPLA2 is transiently recruited to the plasma membranes by a functional NADPH oxidase in neutrophils and in granulocyte-like PLB-985 cells. Coimmunoprecipitation experiments and double labeling immunofluorescence analysis demonstrated the unique colocalization of cPLA2 and the NADPH oxidase in plasma membranes of stimulated cells, in correlation with the kinetic burst of superoxide production. A specific affinity in vitro binding was detected between GST-p47phox or GST-p67phox and cPLA2 in lysates of stimulated cells. The association between these two enzymes provides the molecular basis for AA released by cPLA2 to activate the assembled NADPH oxidase. The ability of cPLA2 to regulate two different functions in the same cells (superoxide generation and eicosanoid production) is achieved by a novel dual subcellular localization of cPLA2 to different targets. PMID:12913107

  15. [Establishment of double targets of high throughput screening model for xanthine oxidase inhibitors and superoxide anion scavengers].

    PubMed

    Xie, Tao; Qin, Zhi-Zhen; Zhou, Rui; Zhao, Ying; Du, Guan-hua

    2015-04-01

    A double targets of high throughput screening model for xanthine oxidase inhibitors and superoxide anion scavengers was established. In the reaction system of xanthine oxidase, WST-1 works as the probe for the ultra oxygen anion generation, and product uric acid works as xanthine oxidase activity indicator. By using SpectraMax M5 continuous spectrum enzyme sign reflectoscope reflector, the changes of these indicators' concentration were observed and the influence factors of this reaction system to establish the high throughput screening model were studied. And the model is confirmed by positive drugs. In the reaction system, the final volume of reaction system is 50 μL and the concentrations of xanthine oxidase is 4 mU x mL(-1), xanthine 250 μmol x L(-1) and WST-1 100 μmol x L(-1), separately. The Z'-factor of model for xanthine oxidase inhibitors is 0.537 4, S/N is 47.519 9; the Z'-factor of model for superoxide anion scavengers is 0.507 4, S/N is 5.388 9. This model for xanthine oxidase inhibitors and superoxide anion scavengers has more common characteristics of the good stability, the fewer reagent types and quantity, the good repeatability, and so on. And it can be widely applied in high-throughput screening research.

  16. Thermostable Xanthine Oxidase Activity from Bacillus pumilus RL-2d Isolated from Manikaran Thermal Spring: Production and Characterization.

    PubMed

    Sharma, Nirmal Kant; Thakur, Shikha; Thakur, Neerja; Savitri; Bhalla, Tek Chand

    2016-03-01

    Xanthine oxidase is an important enzyme of purine metabolism that catalyzes the hydroxylation of hypoxanthine to xanthine and then xanthine to uric acid. A thermostable xanthine oxidase is being reported from a thermophilic organism RL-2d isolated from the Manikaran (Kullu) hot spring of Himachal Pradesh (India). Based on the morphology, physiological tests, and 16S rDNA gene sequence, RL-2d was identified as Bacillus pumilus. Optimization of physiochemical parameters resulted into 4.1-fold increase in the xanthine oxidase activity from 0.051 U/mg dcw (dry cell weight) to 0.209 U/mg dcw. The xanthine oxidase of B. pumilus RL-2d has exhibited very good thermostability and its t1/2 at 70 and 80 °C were 5 and 1 h, respectively. Activity of this enzyme was strongly inhibited by Hg(2+), Ag(+) and allopurinol. The investigation showed that B. pumilus RL-2d exhibited highest xanthine oxidase activity and remarkable thermostability among the other xanthine oxidases reported so far.

  17. Structure–function characterization reveals new catalytic diversity in the galactose oxidase and glyoxal oxidase family

    PubMed Central

    Yin, DeLu (Tyler); Urresti, Saioa; Lafond, Mickael; Johnston, Esther M.; Derikvand, Fatemeh; Ciano, Luisa; Berrin, Jean-Guy; Henrissat, Bernard; Walton, Paul H.; Davies, Gideon J.; Brumer, Harry

    2015-01-01

    Alcohol oxidases, including carbohydrate oxidases, have a long history of research that has generated fundamental biological understanding and biotechnological applications. Despite a long history of study, the galactose 6-oxidase/glyoxal oxidase family of mononuclear copper-radical oxidases, Auxiliary Activity Family 5 (AA5), is currently represented by only very few characterized members. Here we report the recombinant production and detailed structure–function analyses of two homologues from the phytopathogenic fungi Colletotrichum graminicola and C. gloeosporioides, CgrAlcOx and CglAlcOx, respectively, to explore the wider biocatalytic potential in AA5. EPR spectroscopy and crystallographic analysis confirm a common active-site structure vis-à-vis the archetypal galactose 6-oxidase from Fusarium graminearum. Strikingly, however, CgrAlcOx and CglAlcOx are essentially incapable of oxidizing galactose and galactosides, but instead efficiently catalyse the oxidation of diverse aliphatic alcohols. The results highlight the significant potential of prospecting the evolutionary diversity of AA5 to reveal novel enzyme specificities, thereby informing both biology and applications. PMID:26680532

  18. Inhibition of rat fat cell lipolysis by monoamine oxidase and semicarbazide-sensitive amine oxidase substrates.

    PubMed

    Visentin, Virgile; Prévot, Danielle; Marti, Luc; Carpéné, Christian

    2003-04-18

    It has been demonstrated that amine oxidase substrates stimulate glucose transport in cardiomyocytes and adipocytes, promote adipogenesis in pre-adipose cell lines and lower blood glucose in diabetic rats. These insulin-like effects are dependent on amine oxidation by semicarbazide-sensitive amine oxidase or by monoamine oxidase. The present study aimed to investigate whether amine oxidase substrates also exhibit another insulin-like property, the inhibition of lipolysis. We therefore tested the influence of tyramine and benzylamine on lipolytic activity in rat adipocytes. These amines did not modify basal lipolysis but dose-dependently counteracted the stimulation induced by lipolytic agents. The response to 10 nM isoprenaline was totally inhibited by tyramine 1 mM. The blockade produced by inhibition of amine oxidase activity or by 1 mM glutathione suggested that the generation of oxidative species, which occurs during amine oxidation, was involved in tyramine antilipolytic effect. Among the products resulting from amine oxidation, only hydrogen peroxide was antilipolytic in a manner that was potentiated by vanadate, as for tyramine or benzylamine. Antilipolytic responses to tyramine and to insulin were sensitive to wortmannin. These data suggest that inhibition of lipolysis is a novel insulin-like effect of amine oxidase substrates which is mediated by hydrogen peroxide generated during amine oxidation.

  19. A New Transgenic Mouse Model for Studying the Neurotoxicity of Spermine Oxidase Dosage in the Response to Excitotoxic Injury

    PubMed Central

    Cervelli, Manuela; Bellavia, Gabriella; D'Amelio, Marcello; Cavallucci, Virve; Moreno, Sandra; Berger, Joachim; Nardacci, Roberta; Marcoli, Manuela; Maura, Guido; Piacentini, Mauro; Amendola, Roberto; Cecconi, Francesco; Mariottini, Paolo

    2013-01-01

    Spermine oxidase is a FAD-containing enzyme involved in polyamines catabolism, selectively oxidizing spermine to produce H2O2, spermidine, and 3-aminopropanal. Spermine oxidase is highly expressed in the mouse brain and plays a key role in regulating the levels of spermine, which is involved in protein synthesis, cell division and cell growth. Spermine is normally released by neurons at synaptic sites where it exerts a neuromodulatory function, by specifically interacting with different types of ion channels, and with ionotropic glutamate receptors. In order to get an insight into the neurobiological roles of spermine oxidase and spermine, we have deregulated spermine oxidase gene expression producing and characterizing the transgenic mouse model JoSMOrec, conditionally overexpressing the enzyme in the neocortex. We have investigated the effects of spermine oxidase overexpression in the mouse neocortex by transcript accumulation, immunohistochemical analysis, enzymatic assays and polyamine content in young and aged animals. Transgenic JoSMOrec mice showed in the neocortex a higher H2O2 production in respect to Wild-Type controls, indicating an increase of oxidative stress due to SMO overexpression. Moreover, the response of transgenic mice to excitotoxic brain injury, induced by kainic acid injection, was evaluated by analysing the behavioural phenotype, the immunodistribution of neural cell populations, and the ultrastructural features of neocortical neurons. Spermine oxidase overexpression and the consequently altered polyamine levels in the neocortex affects the cytoarchitecture in the adult and aging brain, as well as after neurotoxic insult. It resulted that the transgenic JoSMOrec mouse line is more sensitive to KA than Wild-Type mice, indicating an important role of spermine oxidase during excitotoxicity. These results provide novel evidences of the complex and critical functions carried out by spermine oxidase and spermine in the mammalian brain. PMID

  20. Differential expression of the ascorbate oxidase multigene family during fruit development and in response to stress.

    PubMed

    Sanmartin, Maite; Pateraki, Irene; Chatzopoulou, Fani; Kanellis, Angelos K

    2007-03-01

    Ascorbate oxidase (AO, EC 1.10.3.3) is a member of the multicopper oxidases family. It catalyzes the oxidation of ascorbic acid (AA) to dehydroascorbic acid (DHA) via monodehydroascorbate (MDHA), with the concomitant reduction of molecular oxygen to water. In melon (Cucumis melo), ascorbate oxidase is encoded by a multigene family comprising at least four genes. Here, we present the detailed characterization of two melon AO genes, CmAO1 and CmAO4. Gene-specific expression studies of the AO gene family in melon revealed that only CmAO1 and CmAO4 are transcriptionally active and differentially regulated dependent on tissue, developmental stage and external stimuli. Transcripts of the CmAO1 gene are present in floral and fruit tissues, whereas CmAO4 mRNA preferentially accumulates in vegetative tissues. CmAO genes were not detected in melon seeds, but CmAO4 expression is activated upon germination. CmAO4 mRNA steady-state levels are also regulated in response to wounding and heat stress, by hormones (abscisic acid, salicylic acid and jasmonates), AA and copper. These findings suggest that AO gene expression is transcriptionally regulated during fruit development and in response to hormonal cues associated with the control of cell growth and the stress response.

  1. Potential role of NADPH oxidase in pathogenesis of pancreatitis.

    PubMed

    Cao, Wei-Li; Xiang, Xiao-Hui; Chen, Kai; Xu, Wei; Xia, Shi-Hai

    2014-08-15

    Studies have demonstrated that reactive oxygen species (ROS) are closely related to inflammatory disorders. Nicotinamide adenine dinucleotide phosphate oxidase (NOX), originally found in phagocytes, is the main source of ROS in nonphagocytic cells. Besides directly producing the detrimental highly reactive ROS to act on biomolecules (lipids, proteins, and nucleic acids), NOX can also activate multiple signal transduction pathways, which regulate cell growth, proliferation, differentiation and apoptosis by producing ROS. Recently, research on pancreatic NOX is no longer limited to inflammatory cells, but extends to the aspect of pancreatic acinar cells and pancreatic stellate cells, which are considered to be potentially associated with pancreatitis. In this review, we summarize the literature on NOX protein structure, activation, function and its role in the pathogenesis of pancreatitis.

  2. Potential role of NADPH oxidase in pathogenesis of pancreatitis

    PubMed Central

    Cao, Wei-Li; Xiang, Xiao-Hui; Chen, Kai; Xu, Wei; Xia, Shi-Hai

    2014-01-01

    Studies have demonstrated that reactive oxygen species (ROS) are closely related to inflammatory disorders. Nicotinamide adenine dinucleotide phosphate oxidase (NOX), originally found in phagocytes, is the main source of ROS in nonphagocytic cells. Besides directly producing the detrimental highly reactive ROS to act on biomolecules (lipids, proteins, and nucleic acids), NOX can also activate multiple signal transduction pathways, which regulate cell growth, proliferation, differentiation and apoptosis by producing ROS. Recently, research on pancreatic NOX is no longer limited to inflammatory cells, but extends to the aspect of pancreatic acinar cells and pancreatic stellate cells, which are considered to be potentially associated with pancreatitis. In this review, we summarize the literature on NOX protein structure, activation, function and its role in the pathogenesis of pancreatitis. PMID:25133019

  3. Characterization of polyphenol oxidase from blueberry (Vaccinium corymbosum L.).

    PubMed

    Siddiq, M; Dolan, K D

    2017-03-01

    Polyphenol oxidase (PPO) was extracted and characterized from high-bush blueberries. PPO showed an optimum activity at pH 6.1-6.3 and 35°C, with the enzyme showing significant activity over a wide temperature range (25-60°C). Catechol was the most readily oxidized substrate followed by 4-methylcatechol, DL-DOPA, and dopamine. Blueberry PPO showed a Km of 15mM and Vmax of 2.57 ΔA420nm/min×10(-1), determined with catechol. PPO was completely inactivated in 20min at 85°C, however, after 30minat 75°C it showed about 10% residual activity. Thermal treatment at 55 and 65°C for 30min resulted in the partial inactivation of PPO. Ascorbic acid, sodium diethyldithiocarbamic acid, L-cysteine, and sodium metabisulfite were effective inhibitors of PPO at 1.0mM. Benzoic acid and cinnamic acid series inhibitors showed relatively weak inhibition of PPO (21.8-27.6%), even at as high as 2.0mM concentration.

  4. Inhibition of xanthine oxidase by the aldehyde oxidase inhibitor raloxifene: implications for identifying molybdopterin nitrite reductases.

    PubMed

    Weidert, E R; Schoenborn, S O; Cantu-Medellin, N; Choughule, K V; Jones, J P; Kelley, E E

    2014-02-15

    Sources of nitric oxide alternative to nitric oxide synthases are gaining significant traction as crucial mediators of vessel function under hypoxic inflammatory conditions. For example, capacity to catalyze the one electron reduction of nitrite (NO2-) to ·NO has been reported for hemoglobin, myoglobin and molybdopterin-containing enzymes including xanthine oxidoreductase (XOR) and aldehyde oxidase (AO). For XOR and AO, use of selective inhibition strategies is therefore crucial when attempting to assign relative contributions to nitrite-mediated ·NO formation in cells and tissue. To this end, XOR inhibition has been accomplished with application of classic pyrazolopyrimidine-based inhibitors allo/oxypurinol or the newly FDA-approved XOR-specific inhibitor, Uloric® (febuxostat). Likewise, raloxifene, an estrogen receptor antagonist, has been identified as a potent (Ki=1.0 nM) inhibitor of AO. Herein, we characterize the inhibition kinetics of raloxifene for XOR and describe the resultant effects on inhibiting XO-catalyzed ·NO formation. Exposure of purified XO to raloxifene (PBS, pH 7.4) resulted in a dose-dependent (12.5-100 μM) inhibition of xanthine oxidation to uric acid. Dixon plot analysis revealed a competitive inhibition process with a Ki=13 μM. This inhibitory process was more effective under acidic pH; similar to values encountered under hypoxic/inflammatory conditions. In addition, raloxifene also inhibited anoxic XO-catalyzed reduction of NO2- to NO (EC50=64 μM). In contrast to having no effect on XO-catalyzed uric acid production, the AO inhibitor menadione demonstrated potent inhibition of XO-catalyzed NO2- reduction (EC50=60 nM); somewhat similar to the XO-specific inhibitor, febuxostat (EC50=4 nM). Importantly, febuxostat was found to be a very poor inhibitor of human AO (EC50=613 μM) suggesting its usefulness for validating XO-dependent contributions to NO2- reduction in biological systems. Combined, these data indicate care should be taken

  5. Glucose oxidase from Penicillium amagasakiense. Primary structure and comparison with other glucose-methanol-choline (GMC) oxidoreductases.

    PubMed

    Kiess, M; Hecht, H J; Kalisz, H M

    1998-02-15

    The complete amino acid sequence of glucose oxidase from Penicillium amagasakiense was determined by Edman degradation and mass spectrometry of peptide fragments derived from three different specific proteolytic digests and a cyanogen bromide cleavage. The complete sequence of each monomer comprises 587 amino acid residues, contains three cysteine residues, and seven potential N-glycosylation sites, of which at least five were confirmed to be glycosylated. Glucose oxidase from P. amagasakiense shows a high degree of identity (66%) and 79% similarity to glucose oxidase from Aspergillus niger, and is a member of the glucose-methanol-choline (GMC) oxidoreductase family. The tertiary structures of glucose oxidase from A. niger and cholesterol oxidase from Brevibacterium sterolicum were superimposed to provide a template for the sequence comparison of members of the GMC family. The general topology of the GMC oxidoreductases is conserved, with the exception of the presence of an active site lid in cholesterol oxidase and the insertion of additional structural elements in the substrate-binding domain of alcohol oxidase. The overall structure can be divided into five distinct sequence regions: FAD-binding domain, extended FAD-binding domain, flavin attachment loop and intermediate region, FAD covering lid, and substrate-binding domain. The FAD-binding and the extended FAD-binding domains are composed of several separate sequence regions. The other three regions each comprise a single contiguous sequence. Four major consensus patterns have been identified, including the nucleotide-binding consensus sequence close to their N-termini. The functions of the two motifs recently selected by the Genetics Computer Group, Madison, Wisconsin, as additional signature patterns of the GMC oxidoreductases are discussed. The other consensus patterns belong to either the FAD-binding or the extended FAD-binding domain. In addition, the roles of conserved residues are discussed wherever

  6. Studies on polyphenol content, activities and isozymes of polyphenol oxidase and peroxidase during air-curing in three tobacco types.

    PubMed

    Sheen, S J; Calvert, J

    1969-02-01

    The change in polyphenol content in the primed leaves of burley, flue-cured, and Turkish tobaccos during air-curing was related to the activities and isozymes of polyphenol oxidase and peroxidase. The quantity of chlorogenic acid was rapidly reduced during the first week of curing. The decrease in rutin content during curing was less significant, especially when the concentration of chlorogenic acid was high in leaf tissues. This result was further confirmed by in vitro assays with partially purified tobacco polyphenol oxidase.The polyphenol oxidase activity did not differ at any stage of curing in the 3 tobaccos. When the activity was measured by the oxidation of 3,4-dihydroxyphenylalanine it rose rapidly during the first day of curing and then decreased sharply so that in the fully cured leaf only 15% activity remained. The increase in activity was not observed when chlorogenic acid was used as the substrate. A similar level of peroxidase activity was found in the 3 tobaccos before curing. Peroxidase activities increased rapidly during the first 24 hr of curing, declined thereafter, and remained highest in the flue-cured tobacco, less in the Turkish line, and least in the burley at the end of curing process.By polyacrylamide gel block electrophoresis, 10 peroxidase isozyme bands, 2 cationic and 8 anionic, appeared identical in all 3 tobaccos. When catechol replaced benzidine-2 HCl as the electron donor, 1 cationic and 2 anionic peroxidase isozymes did not form. Of interest is that the same 10 peroxidase isozyme bands also exhibited polyphenol oxidase activities when treated with 3,4-dihydroxyphenylalanine or chlorogenic acid. Results suggest that in the crude tobacco leaf extract the peroxidase and polyphenol oxidase may associate as protein complexes, and peroxidase isozymes may differ in electron-donor requirements. Isozyme patterns for both oxidases at various curing intervals differed only quantitatively.

  7. A continuous spectrophotometric method for determining the monophenolase and diphenolase activities of apple polyphenol oxidase.

    PubMed

    Espín, J C; Morales, M; Varón, R; Tudela, J; García-Cánovas, F

    1995-10-10

    A continuous spectrophotometric method for the determination of the monophenolase and diphenolase activities of apple polyphenol oxidase is described. The method is based on the coupling reaction between 3-methyl-2-benzothiazolinone hydrazone (MBTH) and the quinone product of the oxidation of p-hydroxyphenyl propionic acid and 3,4-dihydroxyphenyl propionic acid in the presence of polyphenol oxidase. The lambda(max) and molar absorptivity (epsilon) for the MBTH-quinone adduct have been calculated. The presence of MBTH in the reaction medium decreases the lag period during the expression of monophenolase activity. The high value of V(mas) suggests the existence of a high catalytic constant. This, together with the value of epsilon for the MBTH-quinone adduct, makes this method more sensitive than other continuous methods.

  8. Some kinetic properties of polyphenol oxidase obtained from dill (Anethum graveolens).

    PubMed

    Sakiroğlu, Halis; Oztürk, Ahmet Emin; Pepe, Anil Ece; Erat, Mustafa

    2008-06-01

    Polyphenol oxidase (PPO) was partially purified from dill by (NH4)(2)SO4 precipitation followed by dialysis and gel filtration chromatography. Polyphenol oxidase activity was measured spectrophotometrically at 420 nm using catechol, dopamine and chlorogenic acid as substrates. Optimum pH, temperature, and ionic strength were determined with three substrates. The best substrate of dill PPO was found to be chlorogenic acid. Some kinetic properties of the enzyme such as V(max,) K(M) and V(max)/K(M) were determined for all three substrates. The effects of various inhibitors on the reaction catalysed by the enzyme were tested and I(50) values calculated. The most effective inhibitor was L-cysteine. Activation energies, E(a), were determined from the Arrhenius equation. In addition, activation enthalpy, DeltaH(a), and Q(10) values of the enzyme were also calculated.

  9. Possible role of a histidine residue in the substrate specificity of yeast d-aspartate oxidase.

    PubMed

    Takahashi, Shouji; Shimada, Kozue; Nozawa, Shunsuke; Goto, Masaru; Abe, Katsumasa; Kera, Yoshio

    2016-03-01

    D-Aspartate oxidase (DDO) catalyzes the oxidative deamination of acidic D-amino acids, whereas neutral and basic D-amino acids are substrates of D-amino acid oxidase (DAO). DDO of the yeast Cryptococcus humicola (ChDDO) has much higher substrate specificity to D-aspartate, but the structural features that confer this specificity have not been elucidated. A three-dimensional model of ChDDO suggested that a histidine residue (His56) in the active site might be involved in the unique substrate specificity, possibly through the interaction with the substrate side chain in the active site. His56 mutants with several different amino acid residues (H56A, H56D, H56F, H56K and H56N) exhibited no significant activity toward acidic D-amino acids, but H56A and H56N mutants gained the ability to utilize neutral D-amino acids as substrates, such as D-methionine, D-phenylalanine and D-glutamine, showing the conversion of ChDDO to DAO by these mutations. This conversion was also demonstrated by the sensitivity of these mutants to competitive inhibitors of DAO. These results and kinetic properties of the mutants show that His56 is involved in the substrate specificity of ChDDO and possibly plays a role in the higher substrate specificity toward D-aspartate.

  10. Short communication: An assessment of the use of malaria rapid tests by village health volunteers in rural Laos.

    PubMed

    Mayxay, Mayfong; Newton, Paul N; Yeung, Shunmay; Pongvongsa, Tiengkham; Phompida, Samlane; Phetsouvanh, Rattanaxay; White, Nicholas J

    2004-03-01

    Rapid malaria diagnosis, a key component of malaria control strategies, is hampered by the expense and training requirements of reliable microscopy. Rapid malaria antigen tests may improve the diagnosis of malaria in the rural tropics. After 1 h training 64 village health volunteers (VHVs) from rural Laos, with no previous laboratory experience, performed two malaria rapid diagnostic tests (ParacheckPf and OptiMAL) accurately. The reliability of six VHVs was assessed longitudinally, over 10 months with different frequencies of retraining. Compared with microscopy, error rates in dipstick interpretation were low (<2%) for both tests and were not associated with retraining frequency (P>0.2). Previously untrained Lao VHVs performed malaria rapid tests reliably with high sensitivity and specificity after minimal training.

  11. Enhanced expression of Rhizobium etli cbb₃ oxidase improves drought tolerance of common bean symbiotic nitrogen fixation.

    PubMed

    Talbi, C; Sánchez, C; Hidalgo-Garcia, A; González, E M; Arrese-Igor, C; Girard, L; Bedmar, E J; Delgado, M J

    2012-09-01

    To investigate the involvement of Rhizobium etli cbb(3) oxidase in the response of Phaseolus vulgaris to drought, common bean plants were inoculated with the R. etli strain, CFNX713, overexpressing this oxidase in bacteroids (cbb(3)(+)) and subjected to drought conditions. The negative effect of drought on plant and nodule dryweight, nitrogen content, and nodule functionality was more pronounced in plants inoculated with the wild-type (WT) strain than in those inoculated with the cbb(3)(+) strain. Regardless of the plant treatment, bacteroids produced by the cbb(3)(+) strain showed higher respiratory capacity than those produced by the WT strain. Inoculation of plants with the cbb(3)(+) strain alleviated the negative effect of a moderate drought on the respiratory capacity of bacteroids and the energy charge of the nodules. Expression of the FixP and FixO components of the cbb(3) oxidase was higher in bacteroids of the cbb(3)(+) strain than in those of the WT strain under all experimental conditions. The decline in sucrose synthase activity and the decrease in dicarboxylic acids provoked by moderate drought stress were more pronounced in nodules from plants inoculated with the WT strain than in those inoculated with the cbb(3)(+) strain. Taken together, these results suggest that inoculation of plants with a R. etli strain having enhanced expression of cbb(3) oxidase in bacteroids reduces the sensitivity of P. vulgaris-R. etli symbiosis to drought and can modulate carbon metabolism in nodules.

  12. Formate simultaneously reduces oxidase activity and enhances respiration in Campylobacter jejuni

    PubMed Central

    Kassem, Issmat I.; Candelero-Rueda, Rosario A.; Esseili, Kawthar A.; Rajashekara, Gireesh

    2017-01-01

    The foodborne microaerophilic pathogen, Campylobacter jejuni, possesses a periplasmic formate dehydrogenase and two terminal oxidases, which serve to metabolize formate and facilitate the use of oxygen as a terminal electron acceptor, respectively. Formate, a primary energy source for C. jejuni, inhibits oxidase activity in other bacteria. Here, we hypothesized that formate might affect both energy metabolism and microaerobic survival in C. jejuni. Subsequently, we showed that C. jejuni 81–176 (wildtype) exhibited enhanced chemoattraction to and respiration of formate in comparison to other organic acids. Formate also significantly increased C. jejuni’s growth, motility, and biofilm formation under microaerobic (5% O2) conditions. However, formate reduced oxidase activity under microaerobic conditions as well as aerotolerance and biofilm formation under ambient oxygen conditions. The expression of genes encoding the ribonucleotide reductase (RNR) and proteins that facilitate the use of alternative electron acceptors generally increased in the presence of formate. Taken together, formate might play a role in optimizing C. jejuni’s adaptation to the oxygen-limited gastrointestinal tract of the host. By affecting oxidase activity, formate possibly facilitates shuttling electrons to alternative acceptors, while likely conserving limited oxygen concentrations for other essential functions such as DNA synthesis via RNR which is required for C. jejuni’s growth. PMID:28091524

  13. In vitro xanthine oxidase inhibitory and in vivo hypouricemic activity of herbal coded formulation (Gouticin).

    PubMed

    Akram, Muhammad; Usmanghani, Khan; Ahmed, Iqbal; Azhar, Iqbal; Hamid, Abdul

    2014-05-01

    Currently, natural products have been used in treating gouty arthritis and are recognized as xanthine oxidase inhibitors. Current study was designed to evaluate in vitro xanthine oxidase inhibitory potential of Gouticin and its ingredients extracts and in vivo hypouricemic activity of gouticin tablet 500 mg twice daily. Ethanol extracts of Gouticin and its ingredients were evaluated in vitro, at 200, 100, 50, 25 μ g/ml concentrations for xanthine oxidase inhibitory activity. IC(50) values of Gouticin and its ingredients were estimated. Further, in vivo therapeutic effect of Gouticin was investigated in comparison with allopathic medicine (Allopurinol) to treat gout. Total patients were 200 that were divided into test and control group. Herbal coded medicine (Gouticin) was given to test group and allopathic medicine allopurinol was administered to control group. In vitro, Gouticin has the highest percent inhibition at 96% followed by Allopurinol with 93% inhibition. In vivo study, mean serum uric acid level of patients was 4.62 mg/dl and 5.21mg/dl by use of Gouticin and Allopurinol at end of therapy. The study showed that herbal coded formulation gouticin and its ingredients are potential sources of natural xanthine oxidase inhibitors. Gouticin 500 mg twice daily is more effective than the allopurinol 300mg once daily in the management of gout.

  14. Evaluation of rhesus monkey and guinea pig hepatic cytosol fractions as models for human aldehyde oxidase.

    PubMed

    Choughule, Kanika V; Barr, John T; Jones, Jeffrey P

    2013-10-01

    Aldehyde oxidase (AOX) is a cytosolic enzyme expressed across a wide range of species, including guinea pig and rhesus monkey. These species are believed to be the best preclinical models for studying human AOX-mediated metabolism. We compared AOX activity in rhesus monkeys, guinea pigs, and humans using phthalazine and N-[2-(dimethylamino)ethyl]acridone-4-carboxamide (DACA) as substrates and raloxifene as an inhibitor. Michaelis-Menten kinetics was observed for phthalazine oxidation in rhesus monkey, guinea pig, and human liver cytosol, whereas substrate inhibition was seen with DACA oxidase activity in all three livers. Raloxifene inhibited phthalazine and DACA oxidase activity uncompetitively in guinea pig, whereas mixed-mode inhibition was seen in rhesus monkey. Our analysis of the primary sequence alignment of rhesus monkey, guinea pig, and human aldehyde oxidase isoform 1 (AOX1) along with homology modeling has led to the identification of several amino acid residue differences within the active site and substrate entrance channel of AOX1. We speculate that some of these residues might be responsible for the differences observed in activity. Overall, our data indicate that rhesus monkeys and guinea pigs would overestimate intrinsic clearance in humans and would be unsuitable to use as animal models. Our study also showed that AOX metabolism in species is substrate-dependent and no single animal model can be reliably used to predict every drug response in humans.

  15. Evaluation of Rhesus Monkey and Guinea Pig Hepatic Cytosol Fractions as Models for Human Aldehyde Oxidase

    PubMed Central

    Choughule, Kanika V.; Barr, John T.

    2013-01-01

    Aldehyde oxidase (AOX) is a cytosolic enzyme expressed across a wide range of species, including guinea pig and rhesus monkey. These species are believed to be the best preclinical models for studying human AOX-mediated metabolism. We compared AOX activity in rhesus monkeys, guinea pigs, and humans using phthalazine and N-[2-(dimethylamino)ethyl]acridone-4-carboxamide (DACA) as substrates and raloxifene as an inhibitor. Michaelis-Menten kinetics was observed for phthalazine oxidation in rhesus monkey, guinea pig, and human liver cytosol, whereas substrate inhibition was seen with DACA oxidase activity in all three livers. Raloxifene inhibited phthalazine and DACA oxidase activity uncompetitively in guinea pig, whereas mixed-mode inhibition was seen in rhesus monkey. Our analysis of the primary sequence alignment of rhesus monkey, guinea pig, and human aldehyde oxidase isoform 1 (AOX1) along with homology modeling has led to the identification of several amino acid residue differences within the active site and substrate entrance channel of AOX1. We speculate that some of these residues might be responsible for the differences observed in activity. Overall, our data indicate that rhesus monkeys and guinea pigs would overestimate intrinsic clearance in humans and would be unsuitable to use as animal models. Our study also showed that AOX metabolism in species is substrate-dependent and no single animal model can be reliably used to predict every drug response in humans. PMID:23918666

  16. Cloning and In Situ Expression Studies of the Hydrogenobaculum Arsenite Oxidase Genes▿

    PubMed Central

    Clingenpeel, Scott R.; D'Imperio, Seth; Oduro, Harry; Druschel, Greg K.; McDermott, Timothy R.

    2009-01-01

    Novel arsenite [As(III)] oxidase structural genes (aoxAB) were cloned from Hydrogenobaculum bacteria isolated from an acidic geothermal spring. Reverse transcriptase PCR demonstrated expression throughout the outflow channel, and the aoxB cDNA clones exhibited distribution patterns relative to the physicochemical gradients in the spring. Microelectrode analyses provided evidence of quantitative As(III) transformation within the microbial mat. PMID:19304831

  17. At War in the Shadow of Vietnam: United States Military Aid to the Royal LAO Government 1955-75

    DTIC Science & Technology

    1991-05-01

    Ending the Tripartite Coalition .......... 156 Returning to the Battlefield ............... 157 Project Waterpump .......................... 159 The...personnel" assigned to the attache offices under Project 404. This will include a review of " Waterpump ," the U.S. Air Force program established to...Operation " Waterpump ," and the Defense Attache office xxvii in Laos. I have interviewed and corresponded with dozens of former Air America pilots

  18. Wildlife Trade and Human Health in Lao PDR: An Assessment of the Zoonotic Disease Risk in Markets

    PubMed Central

    Singhalath, Sinpakone; Silithammavong, Soubanh; Khammavong, Kongsy; Fine, Amanda E.; Weisman, Wendy; Douangngeun, Bounlom; Theppangna, Watthana; Keatts, Lucy; Gilbert, Martin; Karesh, William B.; Hansel, Troy; Zimicki, Susan; O’Rourke, Kathleen; Joly, Damien O.; Mazet, Jonna A. K.

    2016-01-01

    Although the majority of emerging infectious diseases can be linked to wildlife sources, most pathogen spillover events to people could likely be avoided if transmission was better understood and practices adjusted to mitigate risk. Wildlife trade can facilitate zoonotic disease transmission and represents a threat to human health and economies in Asia, highlighted by the 2003 SARS coronavirus outbreak, where a Chinese wildlife market facilitated pathogen transmission. Additionally, wildlife trade poses a serious threat to biodiversity. Therefore, the combined impacts of Asian wildlife trade, sometimes termed bush meat trade, on public health and biodiversity need assessing. From 2010 to 2013, observational data were collected in Lao PDR from markets selling wildlife, including information on volume, form, species and price of wildlife; market biosafety and visitor origin. The potential for traded wildlife to host zoonotic diseases that pose a serious threat to human health was then evaluated at seven markets identified as having high volumes of trade. At the seven markets, during 21 observational surveys, 1,937 alive or fresh dead mammals (approximately 1,009 kg) were observed for sale, including mammals from 12 taxonomic families previously documented to be capable of hosting 36 zoonotic pathogens. In these seven markets, the combination of high wildlife volumes, high risk taxa for zoonoses and poor biosafety increases the potential for pathogen presence and transmission. To examine the potential conservation impact of trade in markets, we assessed the status of 33,752 animals observed during 375 visits to 93 markets, under the Lao PDR Wildlife and Aquatic Law. We observed 6,452 animals listed by Lao PDR as near extinct or threatened with extinction. The combined risks of wildlife trade in Lao PDR to human health and biodiversity highlight the need for a multi-sector approach to effectively protect public health, economic interests and biodiversity. PMID:27008628

  19. Possibility to Use Mobile Learning to Promote World Heritage Site Preservation Awareness in Luang Prabang, Lao Pdr: a Readiness Study

    NASA Astrophysics Data System (ADS)

    Poong, Y. S.; Yamaguchi, S.; Takada, J.

    2013-07-01

    This paper elucidates the current state of mobile technology readiness among young adults in higher education institution based on surveys and interviews. Although Lao PDR is ranked as low category in the ICT Index by International Telecommunication Union (ITU), findings show that there exists high level of readiness among the young adults. Recommendations for future research are developed to guide the development of mobile learning application with the aim to promote World Heritage Site preservation awareness.

  20. Hepatitis B vaccine birthdose practices in a country where hepatitis B is endemic - Laos, December 2011-February 2012.

    PubMed

    2013-07-26

    Chronic hepatitis B virus (HBV) infection causes approximately 325,000 deaths from cirrhosis and liver cancer each year in the Western Pacific Region of the World Health Organization (WHO). With an estimated infection prevalence of >8%, HBV is considered highly endemic in Laos and is most commonly transmitted from mother to child during birth and early childhood. A hepatitis B vaccine birth dose (HepB-BD) is needed to prevent mother-to-child HBV transmission. To assess gaps in coverage and identify possible remedies for improvement of coverage, during the 3-month period December 2011-February 2012, the Laos Ministry of Health and WHO staff members surveyed 37 health facilities in five provinces in Laos, inquiring about HepB-BD knowledge and practices among health-care providers and estimating HepB-BD coverage provided by the facilities. For facility-based births, the median HepB-BD coverage was 74% (interquartile range: 39%-97%). Hepatitis B vaccine was not in stock at 18 (49%) of the 37 facilities on the day they were visited. Of the 37 facilities, 17 (46%) assisted with home births, and 23 (62%) conducted postnatal home visits. Of the 17 facilities that assisted with home births, seven (41%) included HepB-BD vaccination as part of the service; of the 23 that conducted postnatal home visits, 15 (65%) provided HepB-BD as part of the visit. However, among those reporting that they provided these outreach services, only 48 births were recorded as attended, and only 81 postnatal visits were recorded as conducted during the 3-month period. Health facilities can help prevent mother-to-child HBV transmission in Laos by ensuring vaccine availability, vaccinating all infants born in the facility, and enhancing outreach services for home births.

  1. Description of two new species of the genus Devadatta from northern Vietnam and central Laos (Odonata: Devadattidae).

    PubMed

    Phan, Quoc Toan; Sasamoto, Akihiko; Hayashi, Fumio

    2015-04-01

    Two new species of the genus Devadatta Kirby, 1890, D. kompieri sp. nov. from northern Vietnam (holotype: male, Mu Cang Chai district, Yen Bai Province) and D. yokoii sp. nov. from central Laos (holotype: male, Vang Vieng, Vientiane Province) are described. These new species are allied to D. ducatrix Lieftinck, 1969, but are distinguished by specific characteristics of their wings and anal appendages. The other Indochinese species are also briefly discussed.

  2. Assessment of farmer knowledge of large ruminant health and production in developing village-level biosecurity in northern Lao PDR.

    PubMed

    Nampanya, S; Rast, L; Khounsy, S; Windsor, P A

    2010-12-01

    The purpose of this study was to determine baseline knowledge and identify knowledge gaps of farmers on biosecurity, risk of transmission of transboundary diseases and large ruminant health and production in three provinces of northern Laos, Hua Phan (HP), Luang Prabang (LPB) and Xieng Khoung (XK). The survey was conducted in six villages that are project sites for an Australian Centre for International Agricultural Research (ACIAR) project, with two villages located in each of the three provinces. A census survey was conducted by interview with all 238 farmers participating in the ACIAR project, using a structured questionnaire. The interviews were conducted in Lao language and took 1-2 h per farmer. The answers were recorded in Lao and the survey data were translated into English and transcribed into Microsoft Excel, and a linear mixed model in the Genstat statistical analysis package was used to compare quantitative traits between the target provinces. The results showed that the prediction mean of farmer knowledge scores on parasitic disorders, infectious disease, reproduction and nutrition management were significantly different between the target provinces. The prediction mean of farmer knowledge scores on infectious disease questions ranged between 5.11 in HP to 8.54 in XK of 24 marks (P < 0.001). The prediction mean of total knowledge scores was 13.48 in LPB and 19.29 in XK of 42 marks (P < 0.001). The results indicate both the need for and scope required to attain improvements in farmer knowledge of large ruminant health and production. It was concluded that a participatory research and extension programme to address village-level biosecurity and reduce disease risks, plus enhance large ruminant production capabilities of smallholder producers, is a valid and potentially important strategy to address transboundary disease risk and rural poverty in northern Laos.

  3. Wildlife Trade and Human Health in Lao PDR: An Assessment of the Zoonotic Disease Risk in Markets.

    PubMed

    Greatorex, Zoe F; Olson, Sarah H; Singhalath, Sinpakone; Silithammavong, Soubanh; Khammavong, Kongsy; Fine, Amanda E; Weisman, Wendy; Douangngeun, Bounlom; Theppangna, Watthana; Keatts, Lucy; Gilbert, Martin; Karesh, William B; Hansel, Troy; Zimicki, Susan; O'Rourke, Kathleen; Joly, Damien O; Mazet, Jonna A K

    2016-01-01

    Although the majority of emerging infectious diseases can be linked to wildlife sources, most pathogen spillover events to people could likely be avoided if transmission was better understood and practices adjusted to mitigate risk. Wildlife trade can facilitate zoonotic disease transmission and represents a threat to human health and economies in Asia, highlighted by the 2003 SARS coronavirus outbreak, where a Chinese wildlife market facilitated pathogen transmission. Additionally, wildlife trade poses a serious threat to biodiversity. Therefore, the combined impacts of Asian wildlife trade, sometimes termed bush meat trade, on public health and biodiversity need assessing. From 2010 to 2013, observational data were collected in Lao PDR from markets selling wildlife, including information on volume, form, species and price of wildlife; market biosafety and visitor origin. The potential for traded wildlife to host zoonotic diseases that pose a serious threat to human health was then evaluated at seven markets identified as having high volumes of trade. At the seven markets, during 21 observational surveys, 1,937 alive or fresh dead mammals (approximately 1,009 kg) were observed for sale, including mammals from 12 taxonomic families previously documented to be capable of hosting 36 zoonotic pathogens. In these seven markets, the combination of high wildlife volumes, high risk taxa for zoonoses and poor biosafety increases the potential for pathogen presence and transmission. To examine the potential conservation impact of trade in markets, we assessed the status of 33,752 animals observed during 375 visits to 93 markets, under the Lao PDR Wildlife and Aquatic Law. We observed 6,452 animals listed by Lao PDR as near extinct or threatened with extinction. The combined risks of wildlife trade in Lao PDR to human health and biodiversity highlight the need for a multi-sector approach to effectively protect public health, economic interests and biodiversity.

  4. Improving smallholder food security through investigations of carcass composition and beef marketing of buffalo and cattle in northern Lao PDR.

    PubMed

    Nampanya, Sonevilay; Khounsy, Syseng; Phonvisay, Aloun; Bush, Russell David; Windsor, Peter Andrew

    2015-04-01

    This study determined the carcass composition of Lao indigenous buffalo (Bubalus bubalis) and cattle (Bos indicus), then examined trends in bovine meat marketing following review of records of beef production and prices in the two major cities of Luang Prabang (LPB) and Xieng Khoung (XK) provinces in northern Laos. Samples from 41 buffalo and 81 cattle (n = 122) were collected from animals slaughtered in May-June 2014, with live weights, carcass weights and other carcass-related variables collected. The animals were classified into four age cohort groups (<2, 2-<4, 4-6 and >6 years) with quantitative and dichotomous qualitative traits determined. There were significant differences in buffalo and cattle predicted mean carcass weights between age classification categories (p = 0.003 and 0.001) but not in dressing percentages (p = 0.1 and 0.1). The carcass weight of buffalo was 104 (±23.1)-176 (±12.0) kg compared to 65 (±8.7)-84 (±6.5) kg of cattle, with dressing percentages of 37-40 and 39-42 %, respectively. Despite an average bovine meat price increase of 42-48 % between 2011 and 2013, there was a reduction in the numbers of large ruminants slaughtered in the surveyed cities of LPB (11 %) and XK (7 %), with bovine meat availability per person of 5.2-6.6 kg (LPB) and 3.0-3.8 kg (XK). Improving the sustainability of the bovine meat supply in Laos requires a systems approach involving improvements to animal health and production, livestock marketing, plus the critical development of improved slaughterhouse facilities enabling a meat-processing sector to emerge. This development pathway is of particular importance for building the capacity of Laos to reduce food insecurity and alleviate the poverty of its largely rural smallholder community.

  5. Evaluation of Molecular Methods To Improve the Detection of Burkholderia pseudomallei in Soil and Water Samples from Laos

    PubMed Central

    Knappik, Michael; Dance, David A. B.; Rattanavong, Sayaphet; Pierret, Alain; Ribolzi, Olivier; Davong, Viengmon; Silisouk, Joy; Vongsouvath, Manivanh; Newton, Paul N.

    2015-01-01

    Burkholderia pseudomallei is the cause of melioidosis, a severe and potentially fatal disease of humans and animals. It is endemic in northern Australia and Southeast Asia and is found in soil and surface water. The environmental distribution of B. pseudomallei worldwide and within countries where it is endemic, such as the Lao People's Democratic Republic (Laos), remains unclear. However, this knowledge is important to our understanding of the ecology and epidemiology of B. pseudomallei and to facilitate public health interventions. Sensitive and specific methods to detect B. pseudomallei in environmental samples are therefore needed. The aim of this study was to compare molecular and culture-based methods for the detection of B. pseudomallei in soil and surface water in order to identify the optimal approach for future environmental studies in Laos. Molecular detection by quantitative real-time PCR (qPCR) was attempted after DNA extraction directly from soil or water samples or after an overnight enrichment step. The positivity rates obtained by qPCR were compared to those obtained by different culture techniques. The rate of detection from soil samples by qPCR following culture enrichment was significantly higher (84/100) than that by individual culture methods and all culture methods combined (44/100; P < 0.001). Similarly, qPCR following enrichment was the most sensitive method for filtered river water compared with the sensitivity of the individual methods and all individual methods combined. In conclusion, molecular detection following an enrichment step has proven to be a sensitive and reliable approach for B. pseudomallei detection in Lao environmental samples and is recommended as the preferred method for future surveys. PMID:25819969

  6. Involvement of monoamine oxidase and diamine oxidase in the metabolism of the cell differentiating agent hexamethylene bisacetamide (HMBA).

    PubMed

    Conley, B A; Callery, P S; Egorin, M J; Subramanyam, B; Geelhaar, L A; Pan, S S

    1988-01-01

    We have previously demonstrated a number of metabolites of hexamethylene bisacetamide (HMBA) in the urine of patients treated with HMBA. These include N-acetyl-1,6-diaminohexane (NADAH), 6-acetamidohexanoic acid (6AcHA), 1,6-diaminohexane (DAH) and 6-aminohexanoic acid (6AmHA). Because these compounds have potential roles in the dose-limiting metabolic acidosis and neurotoxicity associated with HMBA therapy, and are similar in structure to known substrates of monoamine oxidase (MAO) and diamine oxidase (DAO), we investigated the activities of these enzymes in the metabolic interconversion of HMBA metabolites. NADAH (5 mM) was incubated with MAO and aldehyde dehydrogenase. 6AcHA production was verified by gas chromatography-mass spectrometry and quantified by gas chromatography. 6AcHA production was linear for up to 4 hr. Complete inhibition of MAO activity was observed with 2 mM tranyl-cypromine or pargyline. Mouse liver microsomes, which do not contain MAO, did not convert NADAH to 6AcHA and, in control experiments, did not degrade 6AcHA. The HMBA metabolite, DAH, was a substrate for DAO, producing 3,4,5,6-tetrahydro-2H-azepine. Participation of DAO in the metabolism of HMBA implies potential interaction of HMBA and metabolites with polyamine metabolism and may represent a mechanism for HMBA's effects on cellular growth and differentiation. Metabolism of NADAH, also a differentiator, by MAO implies that concurrent use of HMBA and an MAO inhibitor may be clinically useful.

  7. Diphenol activation of the monophenolase and diphenolase activities of field bean (Dolichos lablab) polyphenol oxidase.

    PubMed

    Gowda, Lalitha R; Paul, Beena

    2002-03-13

    This paper reports a study on the hydroxylation of ferulic acid and tyrosine by field bean (Dolichos lablab) polyphenol oxidase, a reaction that does not take place without the addition of catechol. A lag period similar to the characteristic lag of tyrosinase activity was observed, the length of which decreased with increasing catechol concentration and increased with increasing ferulic acid concentration. The activation constant K(a) of catechol for ferulic acid hydroxylation reaction was 5 mM. The kinetic parameters of field bean polyphenol oxidase toward ferulic acid and tyrosine were evaluated in the presence of catechol. 4-Methyl catechol, L-dihydroxyphenylalanine, pyrogallol, and 2,3,4-trihydroxybenzoic acid, substrates with high binding affinity to field bean polyphenol oxidase, could stimulate this hydroxylation reaction. In contrast, diphenols such as protocatechuic acid, gallic acid, chlorogenic acid, and caffeic acid, which were not substrates for the oxidation reaction, were unable to bring about this activation. It is most likely that only o-diphenols that are substrates for the diphenolase serve as cosubstrates by donating electrons at the active site for the monophenolase activity. The reaction mechanism for this activation is consistent with that proposed for tyrosinase (Sanchez-Ferrer, A.; Rodriguez-Lopez, J. N.; Garcia-Canovas, F.; Garcia-Carmona, F. Biochim. Biophys. Acta 1995, 1247, 1-11). The presence of o-diphenols, viz. catechol, L-dihydroxyphenylalanine, and 4-methyl catechol, is also necessary for the oxidation of the diphenols, caffeic acid, and catechin to their quinones by the field bean polyphenol oxidase. This oxidation reaction occurs immediately with no lag period and does not occur without the addition of diphenol. The kinetic parameters for caffeic acid (K(m) = 0.08 mM, V(max) = 32440 u/mg) in the presence of catechol and the activation constant K(a) of catechol (4.6 mM) for this reaction were enumerated. The absence of a lag

  8. Natural Compounds as Modulators of NADPH Oxidases

    PubMed Central

    2013-01-01

    Reactive oxygen species (ROS) are cellular signals generated ubiquitously by all mammalian cells, but their relative unbalance triggers also diseases through intracellular damage to DNA, RNA, proteins, and lipids. NADPH oxidases (NOX) are the only known enzyme family with the sole function to produce ROS. The NOX physiological functions concern host defence, cellular signaling, regulation of gene expression, and cell differentiation. On the other hand, increased NOX activity contributes to a wide range of pathological processes, including cardiovascular diseases, neurodegeneration, organ failure, and cancer. Therefore targeting these enzymatic ROS sources by natural compounds, without affecting the physiological redox state, may be an important tool. This review summarizes the current state of knowledge of the role of NOX enzymes in physiology and pathology and provides an overview of the currently available NADPH oxidase inhibitors derived from natural extracts such as polyphenols. PMID:24381714

  9. Lysyl Oxidase and the Tumor Microenvironment

    PubMed Central

    Wang, Tong-Hong; Hsia, Shih-Min; Shieh, Tzong-Ming

    2016-01-01

    The lysyl oxidase (LOX) family of oxidases contains a group of extracellular copper-dependent enzymes that catalyze the cross-linking of collagen and elastin by oxidation, thus maintaining the rigidity and structural stability of the extracellular matrix (ECM). Aberrant expression or activation of LOX alters the cellular microenvironment, leading to many diseases, including atherosclerosis, tissue fibrosis, and cancer. Recently, a number of studies have shown that LOX is overexpressed in most cancers and that it is involved in the regulation of tumor progression and metastasis. In contrast, a few reports have also indicated the tumor-suppressing role of LOX. In this short review, we discuss recent research on the correlations between LOX and cancer. Further, the role of LOX in tumor microenvironment remodeling, tumorigenesis, and metastasis and the underlying mechanisms have also been elucidated. PMID:28036074

  10. Development of an analytical method for quantitative comparison of the e-waste management systems in Thailand, Laos, and China.

    PubMed

    Liang, Li; Sharp, Alice

    2016-11-01

    This study employed a set of quantitative criteria to analyse the three parameters; namely policy, process, and practice; of the respective e-waste management systems adopted in Thailand, Laos, and China. Questionnaire surveys were conducted to determine the current status of the three parameters in relation to mobile phones. A total of five, three, and six variables under Policy (P1), Process (P2), and Practice (P3), respectively, were analysed and their weighted averages were calculated. The results showed that among the three countries surveyed, significant differences at p<0.01 were observed in all the P1, P2, and P3 variables, except P305 (sending e-waste to recovery centres) and P306 (treating e-waste by retailers themselves). Based on the quantitative method developed in this study, Laos' e-waste management system received the highest scores in both P1 average (0.130) and P3 average (0.129). However, in the combined Ptotal, China scored the highest (0.141), followed by Laos (0.132) and Thailand (0.121). This method could be used to assist decision makers in performing quantitative analysis of complex issues associating with e-waste management in a country.

  11. A field study on feed supplementation, body weight and selected blood parameters in local pigs in Laos.

    PubMed

    Chittavong, Malavanh; Lindberg, Jan Erik; Jansson, Anna

    2013-02-01

    The aim of the present study was to investigate feed allowances, body weight (BW), haematocrit, haemoglobin, plasma ionised calcium (iCa), sodium, potassium, pH and glucose concentration and faecal K/Na ratio in local growing pigs, sows and piglets kept by small-holder farmers in Laos. Starting hypotheses were that (1) local pigs are under fed, (2) BW is higher in pigs receiving supplementary feed and (3) the blood profile of pigs subjected to very poor nutrition is outside the normal range. On 54 pig-keeping smallholdings in Borikhamxay province, Lao PDR, daily feed allowances were weighed and BW recorded for 27 lactating sows, 54 piglets and 27 growing pigs. Blood samples were collected from the vena jugularis in all pigs. Feed supplementation did not affect BW, but plasma iCa concentration was outside the normal range for all pigs. There was a tendency for lower faecal K/Na ratio in Na-supplemented sows. The results confirm that local pigs in small-scale production systems in Laos suffer from poor nutrition. The most important challenge for farmers appears to be provision of more feed, particularly feed with a high Ca content.

  12. Prevalence of Endemic Pig-Associated Zoonoses in Southeast Asia: A Review of Findings from the Lao People's Democratic Republic

    PubMed Central

    Okello, Anna L.; Burniston, Stephanie; Conlan, James V.; Inthavong, Phouth; Khamlome, Boualam; Welburn, Susan C.; Gilbert, Jeffrey; Allen, John; Blacksell, Stuart D.

    2015-01-01

    The increasing intensification of pork production in southeast Asia necessitates an urgent requirement to better understand the dual impact of pig-associated zoonotic disease on both pig production and human health in the region. Sharing porous borders with five countries and representing many regional ethnicities and agricultural practices, the Lao People's Democratic Republic (Lao PDR) appears well placed to gauge the levels of pig-associated zoonoses circulating in the wider region. Despite this, little is known about the true impact of zoonotic pathogens such as leptospirosis, Trichinella, hepatitis E virus (HEV), Japanese encephalitis (JE), and Taenia solium on human health and livestock production in the country. A comprehensive review of the published prevalences of these five pig-associated zoonoses in Lao PDR has demonstrated that although suspicion remains high of their existence in pig reservoirs across the country, epidemiological data are scarce; only 31 epidemiological studies have been undertaken on these diseases in the past 25 years. A greater understanding of the zoonoses prevalence and subsequent risks associated with pork production in the southeast Asian region could help focus public health and food safety interventions at key points along the value chain, benefiting both livestock producers and the broader animal and human health systems in the region. PMID:25802431

  13. Lysyl oxidase mediates hypoxic control of metastasis.

    PubMed

    Erler, Janine T; Giaccia, Amato J

    2006-11-01

    Hypoxic cancer cells pose a great challenge to the oncologist because they are especially aggressive, metastatic, and resistant to therapy. Recently, we showed that elevation of the extracellular matrix protein lysyl oxidase (LOX) correlates with metastatic disease and is essential for hypoxia-induced metastasis. In an orthotopic rodent model of breast cancer, a small-molecule or antibody inhibitor of LOX abolished metastasis, offering preclinical validation of this enzyme as a therapeutic target.

  14. Ligand interactions with galactose oxidase: mechanistic insights.

    PubMed Central

    Whittaker, M M; Whittaker, J W

    1993-01-01

    Interactions between galactose oxidase and small molecules have been explored using a combination of optical absorption, circular dichroism, and electron paramagnetic resonance (EPR) spectroscopies to detect complex formation and characterize the products. Anions bind directly to the cupric center in both active and inactive galactose oxidase, converting to complexes with optical and EPR spectra that are distinctly different from those of the starting aquo enzyme. Azide binding is coupled to stoichiometric proton uptake by the enzyme, reflecting the generation of a strong base (pKa > 9) in the active site anion adduct. At low temperature, the aquo enzyme converts to a form that exhibits the characteristic optical and EPR spectra of an anion complex, apparently reflecting deprotonation of the coordinated water. Anion binding results in a loss of the optical transition arising from coordinated tyrosine, implying displacement of the axial tyrosine ligand on forming the adduct. Nitric oxide binds to galactose oxidase, forming a specific complex exhibiting an unusual EPR spectrum with all g values below 2. The absence of Cu splitting in this spectrum and the observation that the cupric EPR signal from the active site metal ion is not significantly decreased in the complex suggest a nonmetal interaction site for NO in galactose oxidase. These results have been interpreted in terms of a mechanistic scheme where substrate binding displaces a tyrosinate ligand from the active site cupric ion, generating a base that may serve to deprotonate the coordinated hydroxyl group of the substrate, activating it for oxidation. The protein-NO interactions may probe a nonmetal O2 binding site in this enzyme. PMID:8386015

  15. Imaging Monoamine Oxidase in the Human Brain

    SciTech Connect

    Fowler, J. S.; Volkow, N. D.; Wang, G-J.; Logan, Jean

    1999-11-10

    Positron emission tomography (PET) studies mapping monoamine oxidase in the human brain have been used to measure the turnover rate for MAO B; to determine the minimum effective dose of a new MAO inhibitor drug lazabemide and to document MAO inhibition by cigarette smoke. These studies illustrate the power of PET and radiotracer chemistry to measure normal biochemical processes and to provide information on the effect of drug exposure on specific molecular targets.

  16. Tetrazolium Oxidase Polymorphism in Rainbow Trout

    PubMed Central

    Cederbaum, Stephen D.; Yoshida, Akira

    1972-01-01

    Tetrazolium oxidase from the blood and liver of rainbow trout was found to be genetically polymorphic. The inheritance pattern of the liver enzyme was compatible only with a one locus-two allele hypothesis. The enzymes in the blood while having an electrophoretically identical polymorphism could differ genotypically from that of the liver in a given fish. The significance of these findings to the understanding of the evolution of the salmonid genome is discussed. PMID:4675090

  17. Xanthine dehydrogenase to xanthine oxidase conversion in ischemic rat intestine

    SciTech Connect

    McKelvey, T.G.; Engerson, T.D.; Elmore, C.R.; Jones, H.P. )

    1990-02-26

    The ischemic conversion of the NADH-producing xanthine dehydrogenase (XDH) to an oxidase form, that produces both superoxide radical and hydrogen peroxide, has been proposed as an important step in initiating oxygen radical-mediated ischemia-reperfusion injury. It has also been reported that two forms of converted oxidase are produced in ischemic rat liver; a reversible xanthine oxidase produced through sulfhydryl oxidation, that can be reconverted to XDH by incubation with 10mM dithiothreitol (Dtt) at 37{degrees}C, and a Dtt-irreversible oxidase produced via proteolysis. The authors report that increased oxidase in the ischemic rat intestine results from significant increases in both the Dtt-reversible and Dtt-irreversible forms of xanthine oxidase. Total oxidase activity (Irreversible + Dtt-reversible) was 19% of the total enzyme activity (XDH + XO) in control ileum and distal jejunum, increased to 26% after 1 hour of ischemia at 37{degrees}C, and significantly to 36% after 1.5 hours. After 3 hours 73% of the activity was in the oxidase form. Irreversible oxidase comprised 15% of the total activity in control intestine, significantly increased to 25% after 2 hours, and further to 42% after 3 hours. Dtt-reversible oxidase was 3% of the total activity in controls, increased to 13% after 1.5 hours, and significantly to 29% after 2 hours.

  18. Characterization of polyphenol oxidase activity in Ataulfo mango.

    PubMed

    Cheema, Summervir; Sommerhalter, Monika

    2015-03-15

    Crude extracts of Ataulfo exhibited polyphenol oxidase (PPO) activity with pyrogallol, 3-methylcatechol, catechol, gallic acid, and protocatechuic acid. The substrate dependent pH optima ranged from pH 5.4 to 6.4 with Michaelis-Menten constants between 0.84 ± 0.09 and 4.6 ± 0.7 mM measured in MES or phosphate buffers. The use of acetate buffers resulted in larger Michaelis-Menten constants, up to 14.62 ± 2.03 mM. Sodium ascorbate, glutathione, and kojic acid are promising inhibitors to prevent enzymatic browning in Ataulfo. PPO activity increased with ripeness and was always higher in the skin compared to the pulp. Sodium dodecyl sulphate (SDS) enhanced PPO activity, with pulp showing a stronger increase than skin. SDS-PAGE gels stained for catecholase activity showed multiple bands, with the most prominent bands at apparent molecular weights of 53, 112, and 144 kDa.

  19. Substrate specificity of guinea pig liver aldehyde oxidase and bovine milk xanthine oxidase for methyl- and nitrobenzaldehydes.

    PubMed

    Veskoukis, Aristidis S; Kouretas, Demetrios; Panoutsopoulos, Georgios I

    2006-01-01

    Both aldehyde oxidase and xanthine oxidase catalyze the oxidation of a wide range of N-heterocycles and aldehydes. These enzymes are important in the oxidation of N-heterocyclic xenobiotics, whereas their role in the oxidation of xenobiotic aldehydes is usually ignored. The present investigation describes the interaction of methyl- and nitrosubstituted benzaldehydes, in the ortho-, meta- and parapositions, with guinea pig liver aldehyde oxidase and bovine milk xanthine oxidase. The kinetic constants showed that most substituted benzaldehydes are excellent substrates of aldehyde oxidase with lower affinities for xanthine oxidase. Low Km values for aldehyde oxidase were observed with most benzaldehydes tested, with 3-nitrobenzaldehyde having the lowest Km value and 3-methylbenzaldehyde being the best substrate in terms of substrate efficiency (Ks). Additionally, low Km values for xanthine oxidase were found with most benzaldehydes tested. However, all benzaldehydes also had low Vmax values, which made them poor substrates of xanthine oxidase. It is therefore possible that aldehyde oxidase may be critical in the oxidation of xenobiotic and endobiotic derived aldehydes and its role in such reactions should not be ignored.

  20. Purification and characterisation of polyphenol oxidase (PPO) from eggplant (Solanum melongena).

    PubMed

    Mishra, Bibhuti B; Gautam, Satyendra; Sharma, Arun

    2012-10-15

    Eggplant (Solanum melongena) is a very rich source of polyphenol oxidase (PPO), which negatively affects its quality upon cutting and postharvest processing due to enzymatic browning. PPO inhibitors, from natural or synthetic sources, are used to tackle this problem. One isoform of PPO was 259-fold purified using standard chromatographic procedures. The PPO was found to be a 112 kDa homodimer. The enzyme showed very low K(m) (0.34 mM) and high catalytic efficiency (3.3×10(6)) with 4-methyl catechol. The substrate specificity was in the order: 4-methyl catechol>tert-butylcatechol>dihydrocaffeic acid>pyrocatechol. Cysteine hydrochloride, potassium metabilsulphite, ascorbic acid, erythorbic acid, resorcylic acid and kojic acid showed competitive inhibition, whereas, citric acid and sodium azide showed mixed inhibition of PPO activity. Cysteine hydrochloride was found to be an excellent inhibitor with the low inhibitor constant of 1.8 μM.

  1. The ccoNOQP gene cluster codes for a cb-type cytochrome oxidase that functions in aerobic respiration of Rhodobacter capsulatus.

    PubMed

    Thöny-Meyer, L; Beck, C; Preisig, O; Hennecke, H

    1994-11-01

    The genes for a new type of a haem-copper cytochrome oxidase were cloned from Rhodobacter capsulatus strain 37b4, using the Bradyrhizobium japonicum fixNOQP gene region as a hybridizing probe. Four genes, probably organized in an operon (ccoNOQP), were identified; their products share extensive amino acid sequence similarity with the FixN, O, Q and P proteins that have recently been shown to be the subunits of a cb-type oxidase. CcoN is a b-type cytochrome, CcoO and CcoP are membrane-bound mono- and dihaem c-type cytochromes and CcoQ is a small membrane protein of unknown function. Genes for a similar oxidase are also present in other non-rhizobial bacterial species such as Azotobacter vinelandii, Agrobacterium tumefaciens and Pseudomonas aeruginosa, as revealed by polymerase chain reaction analysis. A ccoN mutant was constructed whose phenotype, in combination with the structural information on the gene products, provides evidence that the CcoNOQP oxidase is a cytochrome c oxidase of the cb type, which supports aerobic respiration in R. capsulatus and which is probably identical to the cbb3-type oxidase that was recently purified from a different strain of the same species. Mutant analysis also showed that this oxidase has no influence on photosynthetic growth and nitrogen-fixation activity.

  2. A cytochrome ba3 functions as a quinol oxidase in Paracoccus denitrificans. Purification, cloning, and sequence comparison.

    PubMed

    Richter, O M; Tao, J S; Turba, A; Ludwig, B

    1994-09-16

    A quinol oxidase has been purified from the cytoplasmic membrane of Paracoccus denitrificans; its heme composition and CO binding properties identify it as a cytochrome ba3. On SDS gels, the purified enzyme complex is separated into five polypeptides. Using partial peptide sequence information for subunit II, the gene locus has been cloned and sequenced. In a typical operon pattern, four genes were identified: qoxA, -B, -C, and -D, coding for subunits II, I, III, and IV. DNA-derived amino acid sequence comparisons reveal extensive similarities to other members of the terminal oxidase superfamily.

  3. Aerobic fermentation of D-glucose by an evolved cytochrome oxidase-deficient Escherichia coli strain.

    PubMed

    Portnoy, Vasiliy A; Herrgård, Markus J; Palsson, Bernhard Ø

    2008-12-01

    Fermentation of glucose to D-lactic acid under aerobic growth conditions by an evolved Escherichia coli mutant deficient in three terminal oxidases is reported in this work. Cytochrome oxidases (cydAB, cyoABCD, and cbdAB) were removed from the E. coli K12 MG1655 genome, resulting in the ECOM3 (E. coli cytochrome oxidase mutant) strain. Removal of cytochrome oxidases reduced the oxygen uptake rate of the knockout strain by nearly 85%. Moreover, the knockout strain was initially incapable of growing on M9 minimal medium. After the ECOM3 strain was subjected to adaptive evolution on glucose M9 medium for 60 days, a growth rate equivalent to that of anaerobic wild-type E. coli was achieved. Our findings demonstrate that three independently adaptively evolved ECOM3 populations acquired different phenotypes: one produced lactate as a sole fermentation product, while the other two strains exhibited a mixed-acid fermentation under oxic growth conditions with lactate remaining as the major product. The homofermenting strain showed a D-lactate yield of 0.8 g/g from glucose. Gene expression and in silico model-based analyses were employed to identify perturbed pathways and explain phenotypic behavior. Significant upregulation of ygiN and sodAB explains the remaining oxygen uptake that was observed in evolved ECOM3 strains. E. coli strains produced in this study showed the ability to produce lactate as a fermentation product from glucose and to undergo mixed-acid fermentation during aerobic growth.

  4. NAD(P)H oxidase and renal epithelial ion transport

    PubMed Central

    Schreck, Carlos

    2011-01-01

    A fundamental requirement for cellular vitality is the maintenance of plasma ion concentration within strict ranges. It is the function of the kidney to match urinary excretion of ions with daily ion intake and nonrenal losses to maintain a stable ionic milieu. NADPH oxidase is a source of reactive oxygen species (ROS) within many cell types, including the transporting renal epithelia. The focus of this review is to describe the role of NADPH oxidase-derived ROS toward local renal tubular ion transport in each nephron segment and to discuss how NADPH oxidase-derived ROS signaling within the nephron may mediate ion homeostasis. In each case, we will attempt to identify the various subunits of NADPH oxidase and reactive oxygen species involved and the ion transporters, which these affect. We will first review the role of NADPH oxidase on renal Na+ and K+ transport. Finally, we will review the relationship between tubular H+ efflux and NADPH oxidase activity. PMID:21270341

  5. Multiple mechanisms of NADPH oxidase inhibition by type A and type B Francisella tularensis

    PubMed Central

    McCaffrey, Ramona L.; Schwartz, Justin T.; Lindemann, Stephen R.; Moreland, Jessica G.; Buchan, Blake W.; Jones, Bradley D.; Allen, Lee-Ann H.

    2010-01-01

    Ft is a facultative intracellular pathogen that infects many cell types, including neutrophils. In previous work, we demonstrated that the type B Ft strain LVS disrupts NADPH oxidase activity throughout human neutrophils, but how this is achieved is incompletely defined. Here, we used several type A and type B strains to demonstrate that Ft-mediated NADPH oxidase inhibition is more complex than appreciated previously. We confirm that phagosomes containing Ft opsonized with AS exclude flavocytochrome b558 and extend previous results to show that soluble phox proteins were also affected, as indicated by diminished phosphorylation of p47phox and other PKC substrates. However, a different mechanism accounts for the ability of Ft to inhibit neutrophil activation by formyl peptides, Staphylococcus aureus, OpZ, and phorbol esters. In this case, enzyme targeting and assembly were normal, and impaired superoxide production was characterized by sustained membrane accumulation of dysfunctional NADPH oxidase complexes. A similar post-assembly inhibition mechanism also diminished the ability of anti-Ft IS to confer neutrophil activation and bacterial killing, consistent with the limited role for antibodies in host defense during tularemia. Studies of mutants that we generated in the type A Ft strain Schu S4 demonstrate that the regulatory factor fevR is essential for NADPH oxidase inhibition, whereas iglI and iglJ, candidate secretion system effectors, and the acid phosphatase acpA are not. As Ft uses multiple mechanisms to block neutrophil NADPH oxidase activity, our data strongly suggest that this is a central aspect of virulence. PMID:20610796

  6. Proton-pumping mechanism of cytochrome c oxidase: a kinetic master-equation approach.

    PubMed

    Kim, Young C; Hummer, Gerhard

    2012-04-01

    Cytochrome c oxidase is an efficient energy transducer that reduces oxygen to water and converts the released chemical energy into an electrochemical membrane potential. As a true proton pump, cytochrome c oxidase translocates protons across the membrane against this potential. Based on a wealth of experiments and calculations, an increasingly detailed picture of the reaction intermediates in the redox cycle has emerged. However, the fundamental mechanism of proton pumping coupled to redox chemistry remains largely unresolved. Here we examine and extend a kinetic master-equation approach to gain insight into redox-coupled proton pumping in cytochrome c oxidase. Basic principles of the cytochrome c oxidase proton pump emerge from an analysis of the simplest kinetic models that retain essential elements of the experimentally determined structure, energetics, and kinetics, and that satisfy fundamental physical principles. The master-equation models allow us to address the question of how pumping can be achieved in a system in which all reaction steps are reversible. Whereas proton pumping does not require the direct modulation of microscopic reaction barriers, such kinetic gating greatly increases the pumping efficiency. Further efficiency gains can be achieved by partially decoupling the proton uptake pathway from the active-site region. Such a mechanism is consistent with the proposed Glu valve, in which the side chain of a key glutamic acid shuttles between the D channel and the active-site region. We also show that the models predict only small proton leaks even in the absence of turnover. The design principles identified here for cytochrome c oxidase provide a blueprint for novel biology-inspired fuel cells, and the master-equation formulation should prove useful also for other molecular machines. .

  7. A multicopper oxidase contributes to the copper tolerance of Brucella melitensis 16M.

    PubMed

    Wu, Tonglei; Wang, Shaohua; Wang, Zhen; Peng, Xiaowei; Lu, Yanli; Wu, Qingmin

    2015-06-01

    Copper is a potent antimicrobial agent. Multiple mechanisms of copper tolerance are utilized by some pathogenic bacteria. BMEII0580, which is significantly similar to the multicopper oxidase from Escherichia coli, was predicted to be the probable blue copper protein YacK precursor in Brucella melitensis 16M, and was designated as Brucella multicopper oxidase (BmcO). A bioinformatics analysis indicated that the typical motifs of multicopper oxidases are present in BmcO. BmcO, the expression of which was up-regulated by copper, could catalyze the oxidation of 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), dimethoxyphenol (DMP) and para-phenylenediamine (pPD), which are widely used as substrates for multicopper oxidase. Additionally, BmcO exhibited ferroxidase activity, which indicated that it might play an important role in the Fe(2+) uptake of B. melitensis. Importantly, the mutant strain 16MΔbmcO was more sensitive to copper than the wild-type strain B. melitensis 16M as well as its complementation strain 16MΔbmcO(bmcO). The infection assays of cells showed that similar bacterial numbers of B. melitensis 16M, 16MΔbmcO and 16MΔbmcO(bmcO) strains were recovered from the infected macrophages. This result indicated that BmcO was not essential for B. melitensis intracellular growth. In conclusion, our results confirm that BmcO is a multicopper oxidase and contributes to the copper tolerance of B. melitensis 16M.

  8. Molecular Dynamic Studies of the Complex Polyethylenimine and Glucose Oxidase

    PubMed Central

    Szefler, Beata; Diudea, Mircea V.; Putz, Mihai V.; Grudzinski, Ireneusz P.

    2016-01-01

    Glucose oxidase (GOx) is an enzyme produced by Aspergillus, Penicillium and other fungi species. It catalyzes the oxidation of β-d-glucose (by the molecular oxygen or other molecules, like quinones, in a higher oxidation state) to form d-glucono-1,5-lactone, which hydrolyses spontaneously to produce gluconic acid. A coproduct of this enzymatic reaction is hydrogen peroxide (H2O2). GOx has found several commercial applications in chemical and pharmaceutical industries including novel biosensors that use the immobilized enzyme on different nanomaterials and/or polymers such as polyethylenimine (PEI). The problem of GOx immobilization on PEI is retaining the enzyme native activity despite its immobilization onto the polymer surface. Therefore, the molecular dynamic (MD) study of the PEI ligand (C14N8_07_B22) and the GOx enzyme (3QVR) was performed to examine the final complex PEI-GOx stabilization and the affinity of the PEI ligand to the docking sites of the GOx enzyme. The docking procedure showed two places/regions of major interaction of the protein with the polymer PEI: (LIG1) of −5.8 kcal/mol and (LIG2) of −4.5 kcal/mol located inside the enzyme and on its surface, respectively. The values of enthalpy for the PEI-enzyme complex, located inside of the protein (LIG1) and on its surface (LIG2) were computed. Docking also discovered domains of the GOx protein that exhibit no interactions with the ligand or have even repulsive characteristics. The structural data clearly indicate some differences in the ligand PEI behavior bound at the two places/regions of glucose oxidase. PMID:27801788

  9. Molecular Dynamic Studies of the Complex Polyethylenimine and Glucose Oxidase.

    PubMed

    Szefler, Beata; Diudea, Mircea V; Putz, Mihai V; Grudzinski, Ireneusz P

    2016-10-27

    Glucose oxidase (GOx) is an enzyme produced by Aspergillus, Penicillium and other fungi species. It catalyzes the oxidation of β-d-glucose (by the molecular oxygen or other molecules, like quinones, in a higher oxidation state) to form d-glucono-1,5-lactone, which hydrolyses spontaneously to produce gluconic acid. A coproduct of this enzymatic reaction is hydrogen peroxide (H₂O₂). GOx has found several commercial applications in chemical and pharmaceutical industries including novel biosensors that use the immobilized enzyme on different nanomaterials and/or polymers such as polyethylenimine (PEI). The problem of GOx immobilization on PEI is retaining the enzyme native activity despite its immobilization onto the polymer surface. Therefore, the molecular dynamic (MD) study of the PEI ligand (C14N8_07_B22) and the GOx enzyme (3QVR) was performed to examine the final complex PEI-GOx stabilization and the affinity of the PEI ligand to the docking sites of the GOx enzyme. The docking procedure showed two places/regions of major interaction of the protein with the polymer PEI: (LIG1) of -5.8 kcal/mol and (LIG2) of -4.5 kcal/mol located inside the enzyme and on its surface, respectively. The values of enthalpy for the PEI-enzyme complex, located inside of the protein (LIG1) and on its surface (LIG2) were computed. Docking also discovered domains of the GOx protein that exhibit no interactions with the ligand or have even repulsive characteristics. The structural data clearly indicate some differences in the ligand PEI behavior bound at the two places/regions of glucose oxidase.

  10. Characterization of the multicopper oxidase gene family in Anopheles gambiae

    PubMed Central

    Gorman, Maureen J.; Dittmer, Neal T.; Marshall, Jeremy L.; Kanost, Michael R.

    2008-01-01

    The multicopper oxidase (MCO) family of enzymes includes laccases, which oxidize a broad range of substrates including diphenols, and several oxidases with specific substrates such as iron, copper or ascorbic acid. We have identified five putative MCO genes in the genome of Anopheles gambiae and have cloned cDNAs encompassing the full coding region for each gene. MCO1 mRNA was detected in all developmental stages and in all of the larval and adult tissues tested. We observed an increase in MCO1 transcript abundance in the midguts and Malphighian tubules of adult females following a blood meal and in adult abdominal carcasses in response to an immune challenge. Two alternatively spliced isoforms of MCO2 mRNA were identified. The A isoform of MCO2 was previously detected in larval and pupal cuticle where it probably catalyzes sclerotization reactions (He et al., 2007). The B isoform was transcriptionally upregulated in ovaries in response to a blood meal. MCO3 mRNA was detected in the adult midgut, Malpighian tubules, and male reproductive tissues; like MCO1, it was upregulated in response to an immune challenge or a blood meal. MCO4 and MCO5 were observed primarily in eggs and in the abdominal carcass of larvae. A phylogenetic analysis of insect MCO genes identified putative orthologs of MCO1 and MCO2 in all of the insect genomes tested, whereas MCO3, MCO4 and MCO5 were found only in the two mosquito species analyzed. MCO2 orthologs have especially high sequence similarity, suggesting that they are under strong purifying selection; the A isoforms are more conserved than the B isoforms. The mosquito specific group shares a common ancestor with MCO2. This initial study of mosquito MCOs suggests that MCO2 may be required for egg development or eggshell tanning in addition to cuticle tanning, while MCO1 and MCO3 may be involved in metal metabolism or immunity. PMID:18675911

  11. The terminal quinol oxidase of the hyperthermophilic archaeon Acidianus ambivalens exhibits a novel subunit structure and gene organization.

    PubMed Central

    Purschke, W G; Schmidt, C L; Petersen, A; Schäfer, G

    1997-01-01

    A terminal quinol oxidase has been isolated from the plasma membrane of the crenarchaeon Acidianus ambivalens (DSM 3772) (formerly Desulfurolobus ambivalens), cloned, and sequenced. The detergent-solubilized complex oxidizes caldariella quinol at high rates and is completely inhibited by cyanide and by quinolone analogs, potent inhibitors of quinol oxidases. It is composed of at least five different subunits of 64.9, 38, 20.4, 18.8, and 7.2 kDa; their genes are located in two different operons. doxB, the gene for subunit I, is located together with doxC and two additional small open reading frames (doxE and doxF) in an operon with a complex transcription pattern. Two other genes of the oxidase complex (doxD and doxA) are located in a different operon and are cotranscribed into a common 1.2-kb mRNA. Both operons exist in duplicate on the genome of A. ambivalens. Only subunit I exhibits clear homology to other members of the superfamily of respiratory heme-copper oxidases; however, it reveals 14 transmembrane helices. In contrast, the composition of the accessory proteins is highly unusual; none is homologous to any known accessory protein of cytochrome oxidases, nor do homologs exist in the databases. DoxA is classified as a subunit II equivalent only by analogy of molecular size and hydrophobicity pattern to corresponding polypeptides of other oxidases. Multiple alignments and phylogenetic analysis of the heme-bearing subunit I (DoxB) locate this oxidase at the bottom of the phylogenetic tree, in the branch of heme-copper oxidases recently suggested to be incapable of superstoichiometric proton pumping. This finding is corroborated by lack of the essential amino acid residues delineating the putative H+-pumping channel. It is therefore concluded that A. ambivalens copes with its strongly acidic environment simply by an extreme turnover of its terminal oxidase, generating a proton gradient only by chemical charge separation. PMID:9023221

  12. Mosquito (Diptera: Culicidae) repellency field tests of essential oils from plants traditionally used in Laos.

    PubMed

    Vongsombath, Chanda; Pålsson, Katinka; Björk, Lars; Borg-Karlson, Anna-Karin; Jaenson, Thomas G T

    2012-11-01

    Essential oils of Hyptis suaveolens (Lamiaceae), Croton roxburghii (Euphorbiaceae), and Litsea cubeba (Lauraceae) were tested in the field near Vientiane city, Lao PDR, on humans for repellent activity against mosquitoes. Landing mosquitoes were collected and later identified. The most abundant mosquitoes captured belonged to the genera Armigeres, Culex, and Aedes. All the plant oils tested at concentrations of 1.7 microg/cm(2), 3.3 microg/cm(2), and 6.3 microg/cm(2) were significantly more mosquito repellent than the negative control. Croton oil was significantly repellent against mosquitoes of the three genera at the highest (6.3 microg/cm(2)) concentration tested. Litsea oil was significantly repellent against Armigeres at all (1.7 microg/cm(2), 3.3 microg/cm(2), and 6.3 microg/cm(2)) concentrations tested. Hyptis oil was significantly repellent against Armigeres at 3.3 microg/cm(2) and 6.3 microg/cm(2) and against Culex at 1.7 microg/cm(2) and 6.3 microg/cm(2). The oils were analyzed for chemical content of volatiles, mainly terpenes. Main constituents were beta-pinene, sabinene, and 1,8-cineol from oils of the green parts of H. suaveolens; alpha-pinene, beta-pinene, and alpha-phellandrene from fresh bark of C. roxburghii; and alpha-pinene, beta-phellandrene, sabinene, and 1,8-cineol from fresh fruits of L. cubeba.

  13. Charge fluctuations in a disordered superconductor, LaO1-xFxBiS2

    NASA Astrophysics Data System (ADS)

    Athauda, Anushika; Lee, Seunghun; Louca, Despina; Mizuguchi, Yoshikazu

    2015-03-01

    LaO1-xFxBiS2 is a disordered, non-magnetic superconductor with a transition temperature of 10.8 K at x = 0.5. The parent compound, LaOBiS2, is a band insulator with a layered tetragonal structure. The evolution of the crystal structure and nano-scale atomic fluctuations are investigated as a function of temperature and composition using neutron scattering. Even though the symmetry remains unchanged with doping, lattice strain develops along the c-axis and buckling of the BiS2 plane changes orientation. In addition, strong local distortions are observed around the Bi ion that are in response to charge fluctuations. Two distinct Bi-S plaquettes are present due to atomic displacement of in-plane sulfur because the Bi ion undergoes a charge disproportionation. The charge fluctuations along with spin-orbit coupling most likely play important roles in the mechanism of superconductivity in this system.

  14. Household Demography and Early Childhood Mortality in a Rice-Farming Village in Northern Laos

    PubMed Central

    Tomita, Shinsuke; Parker, Daniel M.; Jennings, Julia A.; Wood, James

    2015-01-01

    This paper extends Alexandr Chayanov’s model of changing household demography (specifically the ratio of food consumers to food producers) and its influence on agricultural behavior so that it includes possible adverse effects of a rising ratio on nutritional status and early childhood mortality within the household. We apply the model to 35 years’ worth of longitudinal demographic and economic data collected in the irrigated-rice growing village of Na Savang in northern Laos. When appropriate controls are included for other household variables, unobserved inter-household heterogeneity, and changes in local conditions and national policy over the study period, the analysis suggests that a unit increase in the household’s consumer/producer ratio induces something like a nine-fold increase in the risk of death among household members aged less than five years. Monte Carlo simulation studies suggest that this may be an over-estimate but also that the effect is probably real and likely to be an important factor in household demography. At the very least, the results suggest that Chayanov’s model still has theoretical relevance and deserves to be revived. PMID:25775467

  15. The first definitive Asian spinosaurid (Dinosauria: Theropoda) from the early cretaceous of Laos

    NASA Astrophysics Data System (ADS)

    Allain, Ronan; Xaisanavong, Tiengkham; Richir, Philippe; Khentavong, Bounsou

    2012-05-01

    Spinosaurids are among the largest and most specialized carnivorous dinosaurs. The morphology of their crocodile-like skull, stomach contents, and oxygen isotopic composition of the bones suggest they had a predominantly piscivorous diet. Even if close relationships between spinosaurids and Middle Jurassic megalosaurs seem well established, very little is known about the transition from a generalized large basal tetanuran to the specialized morphology of spinosaurids. Spinosaurid remains were previously known from the Early to Late Cretaceous of North Africa, Europe, and South America. Here, we report the discovery of a new spinosaurid theropod from the late Early Cretaceous Savannakhet Basin in Laos, which is distinguished by an autapomorphic sinusoidal dorsosacral sail. This new taxon, Ichthyovenator laosensis gen. et sp. nov., includes well-preserved and partially articulated postcranial remains. Although possible spinosaurid teeth have been reported from various Early Cretaceous localities in Asia, the new taxon I. laosensis is the first definite record of Spinosauridae from Asia. Cladistic analysis identifies Ichthyovenator as a member of the sub-clade Baryonychinae and suggests a widespread distribution of this clade at the end of the Early Cretaceous. Chilantaisaurus tashouikensis from the Cretaceous of Inner Mongolia, and an ungual phalanx from the Upper Jurassic of Colorado are also referred to spinosaurids, extending both the stratigraphical and geographical range of this clade.

  16. Early Modern Humans and Morphological Variation in Southeast Asia: Fossil Evidence from Tam Pa Ling, Laos

    PubMed Central

    Demeter, Fabrice; Shackelford, Laura; Westaway, Kira; Duringer, Philippe; Bacon, Anne-Marie; Ponche, Jean-Luc; Wu, Xiujie; Sayavongkhamdy, Thongsa; Zhao, Jian-Xin; Barnes, Lani; Boyon, Marc; Sichanthongtip, Phonephanh; Sénégas, Frank; Karpoff, Anne-Marie; Patole-Edoumba, Elise; Coppens, Yves; Braga, José

    2015-01-01

    Little is known about the timing of modern human emergence and occupation in Eastern Eurasia. However a rapid migration out of Africa into Southeast Asia by at least 60 ka is supported by archaeological, paleogenetic and paleoanthropological data. Recent discoveries in Laos, a modern human cranium (TPL1) from Tam Pa Ling‘s cave, provided the first evidence for the presence of early modern humans in mainland Southeast Asia by 63-46 ka. In the current study, a complete human mandible representing a second individual, TPL 2, is described using discrete traits and geometric morphometrics with an emphasis on determining its population affinity. The TPL2 mandible has a chin and other discrete traits consistent with early modern humans, but it retains a robust lateral corpus and internal corporal morphology typical of archaic humans across the Old World. The mosaic morphology of TPL2 and the fully modern human morphology of TPL1 suggest that a large range of morphological variation was present in early modern human populations residing in the eastern Eurasia by MIS 3. PMID:25849125

  17. Permian continental paleoenvironments in Southeastern Asia: New insights from the Luang Prabang Basin (Laos)

    NASA Astrophysics Data System (ADS)

    Bercovici, Antoine; Bourquin, Sylvie; Broutin, Jean; Steyer, Jean-Sébastien; Battail, Bernard; Véran, Monette; Vacant, Renaud; Khenthavong, Bounxou; Vongphamany, Sotsy

    2012-10-01

    In Laos (Southeastern Asia), Late Paleozoic sediments were identified by early French explorations across Indochina during the late 19th century (Pavie missions), but little work was undertaken to characterize the sedimentological and stratigraphical context until now. From detailed sedimentological and paleontological studies, we propose an interpretation of the depositional environment and of the stratigraphic context of series located on the right bank of the Mekong River in the Luang Prabang Basin where three main formations were described. The silicoclastic Red Claystone Formation, attributed to alluvial plain environment, contains large fragments of unidentified dicynodonts. The Limestones and Sandstones Formation preserves a new macrofloral assemblage displaying affinities with Middle to Late Permian Cathaysian floras of South China. This assemblage occurs as an intercalation within marine calcareous sandstones that have yielded a marine fauna, including the ammonoid Pseudotirolites sp. which indicates a Late Permian (Changhsingian) age. The well-developed Purple Claystones Formation yielded an abundant and well preserved Late Permian fauna composed of a carnivorous amphibian and numerous Dicynodon cranial and postcranial elements. This formation shows a vertical evolution from braided river to alluvial plain with sheet-flood sand bed and bed-load rivers, with a constant supply of volcanic clasts. Results from the analysis of the paleontological associations in the Luang Prabang Basin suggest that a continental communication between Laurussia and the Indochina Block existed during the Permian, allowing for migration of the terrestrial Dicynodon fauna.

  18. An expanding sexual economy along National Route 3 in Luang Namtha Province, Lao PDR.

    PubMed

    Doussantousse, Serge; Sakounnavong, Bounchanh; Patterson, Ian

    2011-12-01

    With some of the lowest development indicators in Southeast Asia, remote upland areas of the Lao People's Democratic Republic are among the poorest in the region. The advent of improved transport and communication links, along with opportunities for wage employment, have accelerated the growth of a cash economy in traditionally isolated farming communities of Luang Namtha Province. Interviews and focus group discussions with young people, women in the sexual service business and health workers indicate that the lure of the new economy is wooing villagers away from their agrarian roots. Motorbikes and mobile phones have expanded the sexual territory of indigenous youth at a time when international commerce and a cash economy along improved highways are bringing new people into the region. Among the concerns for their health and safety are at-risk behaviours involving alcohol and sexual practices, especially HIV and sexually transmitted infections. Of particular concern is the sexual trade in the province with a predominance of young, poorly educated Khmou women providing sexual services in a growing number of entertainment places.

  19. Non-Local Signal in Quasi-2DEG of LAO/STO

    NASA Astrophysics Data System (ADS)

    Jin, Mi-Jin; Moon, Seon Young; Modepalli, Vijayakumar; Jo, Junhyeon; Park, Jungmin; Baek, Seung-Hyub; Yoo, Jung-Woo

    2015-03-01

    Electron gas arizen at the insulating oxide interfaces exhibits high electron mobility, tunable carrier densities and related unique behaviors such as coexistence of superconductivity and ferromagnetism, Kondo resistance, etc. Itinerant electrons at the oxide hetero-interface are predicted to have long spin diffusion length, while they are under the relatively strong Rashba-type spin orbit coupling due to inversion symmetry breaking. We studied non-local spin signal induced by spin orbit coupling with additional gate-controlled Rashba field in quasi-2DEG of LaAlO3/SrTiO (LAO/STO) interface. We fabricated simple hall-bar like geometry to measure non-local signal with the variation of channel length (2 ~ 10 μm). Cleaned sample was patterned using e-beam lithography and reactive ion etching followed by oxygen treatment to anneal out oxygen vacancies. When an electric current flows one line of the hall bar structure, spin orbit coupling will induce the current flow away from the source current channel via spin hall and inverse spin hall effects. The non-local signals were studied under different angles of magnetic field and the variation of applied gate voltage. This work was supported by a grant from (No. 1.140092.01) funded by the Ulsan National Institute of Science and Technology.

  20. The volcaniclastic series from the Luang Prabang Basin, Laos: A witness of a triassic magmatic arc?

    NASA Astrophysics Data System (ADS)

    Rossignol, Camille; Bourquin, Sylvie; Poujol, Marc; Hallot, Erwan; Dabard, Marie-Pierre; Nalpas, Thierry

    2016-04-01

    The paleogeographic evolution of South East Asia (SEA) during the early Mesozoic is still poorly understood and a number of models have recently been put forward to account for the geodynamic evolution of SEA. The Luang Prabang Basin (north Laos), located in the core of a "paleogeographic jigsaw" in SEA, recorded a long lasting volcanism that spanned for ∼ 35 my from the earliest Triassic up to Late Triassic as evidenced by combined stratigraphic and geochronological (U-Pb/zircon) analyses performed on both volcanic and volcaniclastic series. The volcanic rocks are arc tholeiites and calk-alkaline andesites to dacites. The volcaniclastic rocks contain, in part, volcaniclasts produced contemporaneously with sedimentation. Both the volcanic and volcaniclastic series display geochemical features characteristic of a subduction related volcanism. Therefore, the Luang Prabang Basin documents a magmatic arc in a good agreement with the recent recognition of neighboring ophiolitic rocks in the Luang Prabang area. Following a passive margin setting that prevailed from the late Carboniferous to the late Permian, an active margin then initiated along the western margin of the Indochina Block. This active magmatic arc developed as the result of an east-dipping subduction below the Indochina Block during most of the Triassic, at least from ca. 250 to 215 Ma. Subsequently, this oceanic subduction episode must have been followed by a continental collision of the Indochina Block with the eastern Simao Block, at a period that remains to be defined.

  1. Study for urbanization corresponding to socio-economic activities in Savannaket, Laos using satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Kimijiama, S.; Nagai, M.

    2014-06-01

    In Greater Mekong Sub-region (GMS), economic liberalization and deregulation facilitated by GMS Regional Economic Corporation Program (GMS-ECP) has triggered urbanization in the region. However, the urbanization rate and its linkage to socio-economic activities are ambiguous. The objectives of this paper are to: (a) determine the changes in urban area from 1972 to 2013 using remote sensing data, and (b) analyse the relationships between urbanization with respect to socio-economic activities in central Laos. The study employed supervised classification and human visible interpretation to determine changes in urbanization rate. Regression analysis was used to analyze the correlation between the urbanization rate and socio-economic variables. The result shows that the urban area increased significantly from 1972 to 2013. The socio-economic variables such as school enrollment, labour force, mortality rate, water source and sanitation highly correlated with the rate of urbanization during the period. The study concluded that identifying the highly correlated socio-economic variables with urbanization rate could enable us to conduct a further urbanization simulation. The simulation helps in designing policies for sustainable development.

  2. Growing healthy children and communities: Children's insights in Lao People's Democratic Republic.

    PubMed

    Ruiz-Casares, Mónica

    2016-01-01

    A diverse group of 103 children aged 7-11 years old living in family and residential care in rural and urban settings in two northern provinces in Lao People's Democratic Republic participated in group discussions using images and community mapping. Children's identified sources of risk and protection illustrate primary public health and protection concerns and resources. Young children worried about lack of hygiene, unintentional injuries, corporal punishment, and domestic violence. They also expressed concern about gambling and children sleeping in the streets, even if they had never seen any of the latter in their communities. In contrast, food and shelter; artistic, religious, and cultural practices; supportive interpersonal relationships; and schooling largely evoked feelings of safety and belonging. Images that prompted conflicting interpretations surfaced individual and contextual considerations that nuanced analysis. Researchers and decision-makers will benefit from using this developmentally appropriate, context-sensitive child-centred visual method to elicit young children's views of risk and protection. It may also serve as a tool for public health education. Involving young children in the initial selection of images would further enhance the efficiency of the method.

  3. Benefits of improved municipal solid waste management on greenhouse gas reduction in Luangprabang, Laos.

    PubMed

    Vilaysouk, Xaysackda; Babel, Sandhya

    2017-03-16

    Climate change is a consequence of greenhouse gas emissions. Greenhouse gas (GHG) emissions from the waste sector contribute to 3% of total anthropogenic emissions. In this study, applicable solutions for municipal solid waste (MSW) management in Luangprabang (LPB) and Laos were examined. Material flow analysis of MSW was performed to estimate the amount of MSW generated in 2015. Approximately 29,419 tonnes of MSW is estimated for 2015. Unmanaged landfilling was the main disposal method, while MSW open burning was also practiced to some extent. The International Panel on Climate Change 2006 model and the Atmospheric Brown Clouds Emission Inventory Manual were used to estimate GHG emissions from existing MSW management, and total emissions are 33,889 tonnes/year carbon dioxide-equivalents (CO2-eq). Three scenarios were developed in order to reduce GHG emissions and environmental problems. Improvement of the MSW management by expanding MSW collection services, introducing composting and recycling, and avoiding open burning, can be considered as solutions to overcome the problems for LPB. The lowest GHG emissions are achieved in the scenario where composting and recycling are proposed, with the total GHG emissions reduction by 18,264 tonnes/year CO2-eq.

  4. Involvement of Tyr24 and Trp108 in substrate binding and substrate specificity of glycolate oxidase.

    PubMed

    Stenberg, K; Clausen, T; Lindqvist, Y; Macheroux, P

    1995-03-01

    Tyr24 and Trp108 are located in the active site of spinach glycolate oxidase. To elucidate their function in substrate binding and catalysis, they were replaced by phenylalanine and serine, respectively. The [Y24F]glycolate oxidase mutant enzyme showed a tenfold higher Km value for glycolate. L-lactate and DL-2-hydroxybutyrate also showed higher Km values, however, the substrate specificity was unchanged as compared to the wild-type enzyme (Km increases in the order glycolate < DL-2-hydroxybutyrate < L-lactate < L-mandelate). The turnover number and the rate of reduction, found to be rate limiting in catalysis, were only slightly affected by the deletion of the hydroxyl group. These findings suggest that Tyr24 is mostly involved in substrate binding. The spectral features of the [Y24F]glycolate oxidase suggest that a fraction (50-80%) of the protein bears a flavin N(5) adduct instead of the oxidized cofactor. Crystals obtained from the isolated [Y24F]glycolate oxidase mutant protein allowed the determination of the three-dimensional structure. Although the structure was low resolution (0.3 nm), it is evident that the structure determined is that of the N(5) adduct species. In addition to the lacking hydroxyl group of Tyr24, we also observed movements of the amino acid side chains of Arg164 and Trp108, the latter replacing a water molecule in the substrate-binding pocket. Other features predominantly found in the class of flavoprotein oxidases, such as stabilization of the covalent N(5)-sulfite adduct and of the paraquinoid form of 8-mercapto-FMN, were found to be conserved. [W108S]Glycolate oxidase, in contrast, showed dramatic effects on both the Km of substrates as well as the turnover number. The Km for glycolate was increased some hundred fold and the turnover number was decreased 500-fold. In addition, it was found that the higher homologs of glycolate, L-lactate and DL-2-hydroxybutyrate had turnover numbers similar to those found with the wild-type enzyme

  5. 4-Coumaroyl coenzyme A 3-hydroxylase activity from cell cultures of Lithospermum erythrorhizon and its relationship to polyphenol oxidase.

    PubMed

    Wang, Z X; Li, S M; Löscher, R; Heide, L

    1997-11-15

    A 4-coumaroyl-CoA 3-hydroxylase activity was purified 4600-fold from cell cultures of Lithospermum erythrorhizon. The enzyme showed a molecular mass of 42,400 +/- 1700 Da in gel chromatography and required ascorbate, NADH, or NADPH as cofactors. 4-Coumaroyl-CoA, 4-coumarate, p-cresol, and several other phenolic substances, but not tyrosine, were accepted as substrates for the hydroxylation. Besides hydroxylase activity, the enzyme showed diphenol oxidase activity. Both activities were inhibited by diethyldithiocarbamate or beta-mercaptoethanol, although at different concentrations. The enzyme showed striking similarity to a 4-coumaroyl-glucose 3-hydroxylase from sweet potato (Ipomoe batatas) roots, which has reportedly been purified to homogeneity and identified as a specific enzyme of chlorogenic acid biosynthesis. Close examination and comparison to a commercially available polyphenol oxidase, however, suggest that the enzyme activities purified from both Lithospermum and sweet potato are polyphenol oxidases rather than specific enzymes of secondary metabolism.

  6. A pluripotent polyphenol oxidase from the melanogenic marine Alteromonas sp shares catalytic capabilities of tyrosinases and laccases.

    PubMed

    Sanchez-Amat, A; Solano, F

    1997-11-26

    The recently characterized marine melanogenic bacterium MMB-1 contains a pluripotent polyphenol oxidase (PPO) which catalyzes the oxidation of a very wide range of substrates considered specific for tyrosinase or laccase. This range includes monophenols such as L-tyrosine, o-diphenols such as L-dopa, p-diphenols such as hydroquinone, o-aminophenols such as 3-hydroxyanthranilic acid, activated monophenols such as 2,6-dimethoxyphenol and syringaldazine, and chromophores such as ABTS. This is the first report of an enzyme that is able to catalyze the oxidation of compounds so far considered specific for tyrosinases (L-tyrosine) or laccase (syringaldazine), showing cresolase, catechol oxidase and laccase activities. Such PPO could be a very useful model to study the structural requirements, catalytic mechanisms and involvement of the copper sites existing in non-blue and blue copper-oxidases.

  7. Functional identification of a rice ent-kaurene oxidase, OsKO2, using the Pichia pastoris expression system.

    PubMed

    Ko, Kwang-Wook; Lin, Fengqiu; Katsumata, Takumi; Sugai, Yoshinori; Miyazaki, Sho; Kawaide, Hiroshi; Okada, Kazunori; Nojiri, Hideaki; Yamane, Hisakazu

    2008-12-01

    Rice ent-kaurene oxidase 2 (OsKO2) perhaps functions in the early steps of gibberellin biosynthesis. We found that microsomes from the methylotropic yeast Pichia pastoris expressing both OsKO2 and a fungal cytochrome P450 monooxygenase (P450) reductase converted ent-kaurene to ent-kaurenoic acid. This is direct evidence that OsKO2 is involved in the sequential oxidation of ent-kaurene to ent-kaurenoic acid in gibberellin biosynthesis in rice.

  8. Exceptionally high prevalence of infection of Bithynia siamensis goniomphalos with Opisthorchis viverrini cercariae in different wetlands in Thailand and Lao PDR.

    PubMed

    Kiatsopit, Nadda; Sithithaworn, Paiboon; Saijuntha, Weerachai; Boonmars, Thidarut; Tesana, Smarn; Sithithaworn, Jiraporn; Petney, Trevor N; Andrews, Ross H

    2012-03-01

    The carcinogenic liver fluke, Opisthorchis viverrini, requires Bithynia snail intermediate hosts in its life cycle. However, the prevalence of O. viverrini in snail intermediate hosts is typically low (< 1%). Here, we examined B. siamensis goniomphalos from 48 localities in Thailand and The Lao People's Democratic Republic (Lao PDR) and reported high-prevalence levels of O. viverrini. The highest-prevalence levels per locality were 6.93% (mean = 3.04%) in Thailand and 8.37% (mean = 2.01%) in Lao PDR; 4 of 13 localities examined showed prevalence higher than any prevalence previously recorded. The number of cercariae infecting snails and their prevalence were positively correlated with the size of the snails. High prevalence occurred in the Songkram River wetland (Thailand) and the Nam Ngum River wetland (Lao PDR). Our results show that transmission of O. viverrini from humans as well as animal reservoir hosts to snail intermediate hosts is ongoing and potentially increasing in endemic areas across Thailand and Lao PDR.

  9. Genetic differentiation among populations of Brachytrupes portentosus (Lichtenstein 1796) (Orthoptera: Gryllidae) in Thailand and the Lao PDR: the Mekong River as a biogeographic barrier.

    PubMed

    Tantrawatpan, C; Saijuntha, W; Pilab, W; Sakdakham, K; Pasorn, P; Thanonkeo, S; Thiha; Satrawaha, R; Petney, T

    2011-12-01

    The Mekong River is known to act as a boundary between a number of terrestrial and freshwater species, including various parasites and their intermediate hosts as well as endangered mammal species. Little information is available, however, on the genetic differentiation between terrestrial invertebrates to the east and the west of this wide river. The genetic diversity among eight natural populations of Brachytrupes portentosus (Lichtenstein, 1796) (Orthoptera: Gryllidae) collected from Thailand and the Lao People's Democratic Republic (PDR) were analyzed by multilocus enzyme electrophoresis. The allelic profiles of 20 enzymes encoding 23 loci were analyzed. An average of 41% fixed differences was detected between the populations from Thailand and Lao PDR, which are separated by the Mekong River. The percent fixed differences ranged between 4% and 26% within the populations from Thailand and between 4% and 22% within the populations from Lao PDR. A phenogram shows that the eight populations fell into two major clusters based on the Thai and Lao sampling sites. The genetic distance between the samples within Thailand and within Lao PDR was related to the distances between sampling areas. The genetic variability between populations of this cricket indicates that genetic relationships are influenced by a natural barrier as well as by the geographical distance between these allopatric populations.

  10. Genetic relationships within the Opisthorchis viverrini species complex with specific analysis of O. viverrini from Savannakhet, Lao PDR by multilocus enzyme electrophoresis.

    PubMed

    Kiatsopit, Nadda; Sithithaworn, Paiboon; Sithithaworn, Jiraporn; Boonmars, Thidarut; Tesana, Smarn; Pitaksakulrat, Opal; Saijuntha, Weerachai; Petney, Trevor N; Andrews, Ross H

    2011-01-01

    Recent systematic studies of Opisthorchis viverrini based on multilocus enzyme electrophoresis (MEE) have shown that there are at least five genetic groups and possibly two cryptic species occurring in Thailand and Lao PDR each associated with a specific wetland system. A study based on mitochondrial DNA (mtDNA) gene analyses of an O. viverrini population from Savannakhet (SV, Lao PDR) clustered with several isolates from Thailand and Lao PDR although they originated from different river wetland systems. We used MEE to re-examine whether O. viverrini from SV was similar genetically to isolates from Thailand and Lao PDR. The allelic profiles of O. viverrini from SV and five different wetlands representing defined genetic groups of O. viverrini were recorded at 24 enzyme loci as opposed to only two loci of mtDNA. Contrary to previous studies, O. viverrini from SV was found to have fixed genetic differences at six to eight of the 24 loci examined (24.50-35.42%). Allelic data indicated that O. viverrini from SV differed from isolates in the Nam Ngum River wetland in Lao PDR (29.33% fixed genetic differences) and clustered with O. viverrini from Nakhon Phanom and Sakon Nakhon within the Songkram River wetland in Thailand but had fixed genetic differences from these at 24.5% of loci examined. Our data confirm the association between genetic groups of O. viverrini and specific wetland systems, and raise important questions regarding the significance of the genetic differences and relationships of O. viverrini from these wetlands.

  11. Ascorbyl palmitate-loaded chitosan nanoparticles: characteristic and polyphenol oxidase inhibitory activity.

    PubMed

    Kim, Mi Kyung; Lee, Ji-Soo; Kim, Kwang Yup; Lee, Hyeon Gyu

    2013-03-01

    The aim of this study was to produce ascorbyl palmitate (AP)-loaded nanoparticles in order to inhibit polyphenol oxidase (PPO) in bananas. AP-loaded chitosan nanoparticles were prepared using acetic acid and citric acid (denoted as CS/AA and CS/CA nanoparticles, respectively). As the initial AP concentration increases, the particle size significantly decreases, and the zeta potential, entrapment and loading efficiency significantly increases. The PPO inhibitory activity of AP was effectively improved when AP was nano-encapsulated by chitosan compared to no encapsulation. These results suggest that chitosan nano-encapsulation can be used to enhance the PPO inhibitory activity of AP.

  12. Glucose Biosensor Based on Immobilization of Glucose Oxidase in Platinum Nanoparticles/Graphene/Chitosan Nanocomposite Film

    SciTech Connect

    Wu, Hong; Wang, Jun; Kang, Xinhuang; Wang, Chong M.; Wang, Donghai; Liu, Jun; Aksay, Ilhan A.; Lin, Yuehe

    2009-09-01

    T