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Sample records for kas tuumaenergia akumulaatorid

  1. The role of KasA and KasB in the biosynthesis of meromycolic acids and isoniazid resistance in Mycobacterium tuberculosis.

    PubMed

    Slayden, R A; Barry, C E

    2002-01-01

    Mycobacterium tuberculosis has two discrete beta-ketoacyl synthases encoded by kasA and kasB that are located in tandem within a five-gene operon that has been implicated in isoniazid-sensitivity and mycolic acid synthesis. We have developed an in vitro meromycolic acid synthase assay to elucidate the anabolic role of these enzymes. Overproduction of KasA and KasB individually and together in M. smegmatis enabled cell-free incorporation of [(14)C]malonyl-CoA into lipids whose chain length was dependent upon the M. tuberculosis elongating enzyme used. KasA specifically elongated palmitoyl-CoA to monounsaturated fatty acids that averaged 40 carbons in length. KasB hyperproduction in the presence of KasA produced longer chain multiunsaturated hydrocarbons averaging 54 carbons in length. These products comigrated with a synthetic standard of meromycolic acid and their production was sensitive to isoniazid, thiolactomycin, and triclosan. KasA mutations associated with isoniazid resistance produced an enzyme that had a diminished overall catalytic activity but conferred enhanced resistance to isoniazid. In vivo analysis confirmed that overexpression of each of the four mutant KasAs enhanced isoniazid resistance when compared to overexpression of wild-type KasA. These results suggest discrete anabolic roles for both KasA and KasB in mycolic acid synthesis and substantiate the involvement of KasA mutations in isoniazid resistance. PMID:12464486

  2. Purification and biochemical characterization of the Mycobacterium tuberculosis beta-ketoacyl-acyl carrier protein synthases KasA and KasB.

    PubMed

    Schaeffer, M L; Agnihotri, G; Volker, C; Kallender, H; Brennan, P J; Lonsdale, J T

    2001-12-14

    Mycolic acids are vital components of the Mycobacterium tuberculosis cell wall, and enzymes involved in their formation represent attractive targets for the discovery of novel anti-tuberculosis agents. Biosynthesis of the fatty acyl chains of mycolic acids involves two fatty acid synthetic systems, the multifunctional polypeptide fatty acid synthase I (FASI), which performs de novo fatty acid synthesis, and the dissociated FASII system, which consists of monofunctional enzymes, and acyl carrier protein (ACP) and elongates FASI products to long chain mycolic acid precursors. In this study, we present the initial characterization of purified KasA and KasB, two beta-ketoacyl-ACP synthase (KAS) enzymes of the M. tuberculosis FASII system. KasA and KasB were expressed in E. coli and purified by affinity chromatography. Both enzymes showed activity typical of bacterial KASs, condensing an acyl-ACP with malonyl-ACP. Consistent with the proposed role of FASII in mycolic acid synthesis, analysis of various acyl-ACP substrates indicated KasA and KasB had higher specificity for long chain acyl-ACPs containing at least 16 carbons. Activity of KasA and KasB increased with use of M. tuberculosis AcpM, suggesting that structural differences between AcpM and E. coli ACP may affect their recognition by the enzymes. Both enzymes were sensitive to KAS inhibitors cerulenin and thiolactomycin. These results represent important steps in characterizing KasA and KasB as targets for antimycobacterial drug discovery. PMID:11600501

  3. Development of a scintillation proximity assay for the Mycobacterium tuberculosis KasA and KasB enzymes involved in mycolic acid biosynthesis.

    PubMed

    Schaeffer, M L Merrill L; Carson, J D Jeffrey D; Kallender, Howard; Lonsdale, J T John T

    2004-01-01

    Tuberculosis remains a global health problem, and programs dedicated to discovery of novel compounds against Mycobacterium tuberculosis require robust assays for high-throughput screening of chemical and natural product libraries. Enzymes involved in the biosynthesis of mycolic acids, vital components of the mycobacterial cell wall, have received much attention as potential drug targets. KasA and KasB, examples of the beta-ketoacyl-acyl carrier protein synthase I/II (KASI/II) class of condensing enzymes of the M. tuberculosis fatty acid synthase II system have been the focus of several studies designed to biochemically characterize these enzymes. Whilst robust methods have been developed for FabH-like proteins, fast and sensitive assays for high-throughput screening of KASI/II enzymes have not been available. Here we report the development of a direct scintillation proximity assay (SPA) for the KASI/II enzymes, KasA and KasB. The SPA was more sensitive than existing assays, as shown by its ability to measure activity using less enzyme than other assay formats, and the SPA was validated using the known KAS inhibitor thiolactomycin. In addition, the KasA and KasB SPA was adapted for use with Staphylococcus aureus FabF to show the versatility of this assay format to KAS enzymes from other pathogenic organisms. PMID:15525558

  4. Inhibition of InhA activity, but not KasA activity, induces formation of a KasA-containing complex in mycobacteria.

    PubMed

    Kremer, Laurent; Dover, Lynn G; Morbidoni, Hector R; Vilchèze, Catherine; Maughan, William N; Baulard, Alain; Tu, Shiao-Chun; Honoré, Nadine; Deretic, Vojo; Sacchettini, James C; Locht, Camille; Jacobs, William R; Besra, Gurdyal S

    2003-06-01

    Isoniazid (INH) remains one of the key drugs used to control tuberculosis, with the enoyl-AcpM reductase InhA being the primary target. However, based on the observation that INH-treated Mycobacterium tuberculosis overproduces KasA, an enzyme involved in the biosynthesis of mycolic acids, and induces the formation of a covalent complex consisting of AcpM, KasA, and INH, it has been proposed that KasA represents the primary target of INH. However, the relevance of this complex to INH action remains obscure. This study was aimed at clarifying the role of InhA and KasA in relation to INH activity. By using anti-KasA antibodies we detected the KasA-containing complex in INH-treated Mycobacterium smegmatis. In addition, INH-treated cells also produced constant levels of KasA that were not sequestered in the complex and presumably were sufficient to ensure mycolic acid biosynthesis. Interestingly, a furA-lacking strain induced the complex at lower concentrations of INH compared with the control strain, whereas higher INH concentrations were necessary to induce the complex in a strain that lacks katG, suggesting that INH needs to be activated by KatG to induce the KasA-containing complex. The InhA inhibitors ethionamide and diazaborine also induced the complex; thus, its formation was not specifically relevant to INH action but was because of InhA inhibition. In addition, in vitro assays using purified InhA and KasA demonstrated that KatG-activated INH, triclosan, and diazaborine inhibited InhA but not KasA activity. Moreover, several thermosensitive InhA mutant strains of M. smegmatis constitutively expressed the KasA-containing complex. This study provides the biochemical and genetic evidence. 1) Only inhibition of InhA, but not KasA, induces the KasA-containing complex. 2) INH is not part of the complex. 3) INH does not target KasA, consistent with InhA being the primary target of INH. PMID:12654922

  5. SRTM Anaglyph: Haro and Kas Hills

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On January 26, 2001 the Kachchh region in western India suffered the most deadly earthquake in India's history. This three-dimensional view of landforms northeast of the city of Bhuj depicts geologic structures that are of interest in the study the tectonic processes that may have led to that earthquake. However, preliminary field studies indicate that these structures are composed of Mesozoic rocks that are overlain by younger rocks showing little deformation. Thus these structures may be old, not actively growing, and not directly related to the recent earthquake.

    The Haro Hills are on the left and the Kas Hills are on the right. The Haro Hills are an 'anticline,' which is an upwardly convex elongated fold of layered rocks. The anticline is distinctly ringed by an erosion resistant layer of sandstone. The east-west orientation of the anticline may relate to the crustal compression that has occurred during India's northward movement toward, and collision with, Asia. In contrast, the largest of the Kas Hills appears to be a tilted (to the south) and faulted (on the north) block of layered rocks. Also seen here, the curvilinear ridge trending toward the southwest from the image center is an erosion resistant 'dike,' which is an igneous intrusion into older 'host' rocks along a fault plane or other crack. The dike also appears to extend northeast from the image center as a dark line having very little topography. Its location between the tilted block and a smaller anticline to the north (directly east of the larger anticline) probably indicates that the dike fills the fault that separates these contrasting geologic structures. These features are simple examples of how digital elevation data can stereoscopically enhance satellite imagery to provide a direct input to geologic studies.

    The stereoscopic effect of this anaglyph was created by first draping a Landsat satellite image (taken just two weeks after the earthquake) over preliminary digital elevation

  6. Thiolactomycin and related analogues as novel anti-mycobacterial agents targeting KasA and KasB condensing enzymes in Mycobacterium tuberculosis.

    PubMed

    Kremer, L; Douglas, J D; Baulard, A R; Morehouse, C; Guy, M R; Alland, D; Dover, L G; Lakey, J H; Jacobs, W R; Brennan, P J; Minnikin, D E; Besra, G S

    2000-06-01

    Prevention efforts and control of tuberculosis are seriously hampered by the appearance of multidrug-resistant strains of Mycobacterium tuberculosis, dictating new approaches to the treatment of the disease. Thiolactomycin (TLM) is a unique thiolactone that has been shown to exhibit anti-mycobacterial activity by specifically inhibiting fatty acid and mycolic acid biosynthesis. In this study, we present evidence that TLM targets two beta-ketoacyl-acyl-carrier protein synthases, KasA and KasB, consistent with the fact that both enzymes belong to the fatty-acid synthase type II system involved in fatty acid and mycolic acid biosynthesis. Overexpression of KasA, KasB, and KasAB in Mycobacterium bovis BCG increased in vivo and in vitro resistance against TLM. In addition, a multidrug-resistant clinical isolate was also found to be highly sensitive to TLM, indicating promise in counteracting multidrug-resistant strains of M. tuberculosis. The design and synthesis of several TLM derivatives have led to compounds more potent both in vitro against fatty acid and mycolic acid biosynthesis and in vivo against M. tuberculosis. Finally, a three-dimensional structural model of KasA has also been generated to improve understanding of the catalytic site of mycobacterial Kas proteins and to provide a more rational approach to the design of new drugs. PMID:10747933

  7. Conditional depletion of KasA, a key enzyme of mycolic acid biosynthesis, leads to mycobacterial cell lysis.

    PubMed

    Bhatt, Apoorva; Kremer, Laurent; Dai, Annie Z; Sacchettini, James C; Jacobs, William R

    2005-11-01

    Inhibition or inactivation of InhA, a fatty acid synthase II (FASII) enzyme, leads to mycobacterial cell lysis. To determine whether inactivation of other enzymes of the mycolic acid-synthesizing FASII complex also leads to lysis, we characterized the essentiality of two beta-ketoacyl-acyl carrier protein synthases, KasA and KasB, in Mycobacterium smegmatis. Using specialized transduction for allelic exchange, null kasB mutants, but not kasA mutants, could be generated in Mycobacterium smegmatis, suggesting that unlike kasB, kasA is essential. To confirm the essentiality of kasA, and to detail the molecular events that occur following depletion of KasA, we developed CESTET (conditional expression specialized transduction essentiality test), a genetic tool that combines conditional gene expression and specialized transduction. Using CESTET, we were able to generate conditional null inhA and kasA mutants. We studied the effects of depletion of KasA in M. smegmatis using the former strain as a reference. Depletion of either InhA or KasA led to cell lysis, but with different biochemical and morphological events prior to lysis. While InhA depletion led to the induction of an 80-kDa complex containing both KasA and AcpM, the mycobacterial acyl carrier protein, KasA depletion did not induce the same complex. Depletion of either InhA or KasA led to inhibition of alpha and epoxy mycolate biosynthesis and to accumulation of alpha'-mycolates. Furthermore, scanning electron micrographs revealed that KasA depletion resulted in the cell surface having a "crumpled" appearance, in contrast to the blebs observed on InhA depletion. Thus, our studies support the further exploration of KasA as a target for mycobacterial-drug development. PMID:16267284

  8. Contribution of kasA analysis to detection of isoniazid-resistant Mycobacterium tuberculosis in Singapore.

    PubMed

    Lee, A S; Lim, I H; Tang, L L; Telenti, A; Wong, S Y

    1999-08-01

    Genotypic analysis of resistance to isoniazid (INH) in Mycobacterium tuberculosis is complex due to the various genes potentially involved. Mutations in ketoacyl acyl carrier protein synthase (encoded by kasA) were present in 16 of 160 (10%) INH-resistant isolates (R121K [n = 1], G269S [n = 3], G312S [n = 11], G387D [n = 1]). However, G312S was also present in 6 of 32 (19%) susceptible strains. kasA analysis contributed marginally to the performance of INH genotypic testing in Singapore. The significance of kasA polymorphisms in INH resistance should be carefully established. PMID:10428945

  9. Phosphorylation of KasB Regulates Virulence and Acid-Fastness in Mycobacterium tuberculosis

    PubMed Central

    Vilchèze, Catherine; Molle, Virginie; Carrère-Kremer, Séverine; Leiba, Jade; Mourey, Lionel; Shenai, Shubhada; Baronian, Grégory; Tufariello, Joann; Hartman, Travis; Veyron-Churlet, Romain; Trivelli, Xavier; Tiwari, Sangeeta; Weinrick, Brian; Alland, David; Guérardel, Yann; Jacobs, William R.; Kremer, Laurent

    2014-01-01

    Mycobacterium tuberculosis bacilli display two signature features: acid-fast staining and the capacity to induce long-term latent infections in humans. However, the mechanisms governing these two important processes remain largely unknown. Ser/Thr phosphorylation has recently emerged as an important regulatory mechanism allowing mycobacteria to adapt their cell wall structure/composition in response to their environment. Herein, we evaluated whether phosphorylation of KasB, a crucial mycolic acid biosynthetic enzyme, could modulate acid-fast staining and virulence. Tandem mass spectrometry and site-directed mutagenesis revealed that phosphorylation of KasB occurred at Thr334 and Thr336 both in vitro and in mycobacteria. Isogenic strains of M. tuberculosis with either a deletion of the kasB gene or a kasB_T334D/T336D allele, mimicking constitutive phosphorylation of KasB, were constructed by specialized linkage transduction. Biochemical and structural analyses comparing these mutants to the parental strain revealed that both mutant strains had mycolic acids that were shortened by 4–6 carbon atoms and lacked trans-cyclopropanation. Together, these results suggested that in M. tuberculosis, phosphorylation profoundly decreases the condensing activity of KasB. Structural/modeling analyses reveal that Thr334 and Thr336 are located in the vicinity of the catalytic triad, which indicates that phosphorylation of these amino acids would result in loss of enzyme activity. Importantly, the kasB_T334D/T336D phosphomimetic and deletion alleles, in contrast to the kasB_T334A/T336A phosphoablative allele, completely lost acid-fast staining. Moreover, assessing the virulence of these strains indicated that the KasB phosphomimetic mutant was attenuated in both immunodeficient and immunocompetent mice following aerosol infection. This attenuation was characterized by the absence of lung pathology. Overall, these results highlight for the first time the role of Ser/Thr kinase

  10. Identification of KasA as the cellular target of an anti-tubercular scaffold.

    PubMed

    Abrahams, Katherine A; Chung, Chun-Wa; Ghidelli-Disse, Sonja; Rullas, Joaquín; Rebollo-López, María José; Gurcha, Sudagar S; Cox, Jonathan A G; Mendoza, Alfonso; Jiménez-Navarro, Elena; Martínez-Martínez, María Santos; Neu, Margarete; Shillings, Anthony; Homes, Paul; Argyrou, Argyrides; Casanueva, Ruth; Loman, Nicholas J; Moynihan, Patrick J; Lelièvre, Joël; Selenski, Carolyn; Axtman, Matthew; Kremer, Laurent; Bantscheff, Marcus; Angulo-Barturen, Iñigo; Izquierdo, Mónica Cacho; Cammack, Nicholas C; Drewes, Gerard; Ballell, Lluis; Barros, David; Besra, Gurdyal S; Bates, Robert H

    2016-01-01

    Phenotypic screens for bactericidal compounds are starting to yield promising hits against tuberculosis. In this regard, whole-genome sequencing of spontaneous resistant mutants generated against an indazole sulfonamide (GSK3011724A) identifies several specific single-nucleotide polymorphisms in the essential Mycobacterium tuberculosis β-ketoacyl synthase (kas) A gene. Here, this genomic-based target assignment is confirmed by biochemical assays, chemical proteomics and structural resolution of a KasA-GSK3011724A complex by X-ray crystallography. Finally, M. tuberculosis GSK3011724A-resistant mutants increase the in vitro minimum inhibitory concentration and the in vivo 99% effective dose in mice, establishing in vitro and in vivo target engagement. Surprisingly, the lack of target engagement of the related β-ketoacyl synthases (FabH and KasB) suggests a different mode of inhibition when compared with other Kas inhibitors of fatty acid biosynthesis in bacteria. These results clearly identify KasA as the biological target of GSK3011724A and validate this enzyme for further drug discovery efforts against tuberculosis. PMID:27581223

  11. Theoretical estimation of the aqueous pKas of thiols

    NASA Astrophysics Data System (ADS)

    Hunter, Nora E.; Seybold, Paul G.

    2014-02-01

    The ionisation state of a compound is a key parameter influencing the compound's activity as a drug, metabolite, pollutant, or other active chemical agent. Sulfhydrol compounds (thiols) tend to be considerably more acidic than their hydroxyl (alcohol) analogues. In this report, quantum chemical approaches previously used for the estimation of the aqueous pKas of alcohols are applied to the estimation of the acidities of thiols. Acidity estimates obtained from the general-purpose SPARC calculational programme (S.H. Hilal, S.W. Karickhoff, and L.A. Carreira, Quant. Struct.-Act. Relat. 14, 348 (1995)) and the ACD/Labs PhysChem Suite v12 programme package are employed as benchmarks. Quantum chemical calculations were performed using both the semiempirical RM1 method and the density functional theory B3LYP/6-31+G* method. The effectiveness of the SM5.4 and SM8 solvent models in estimating the aqueous-phase acidities was also evaluated. All of the approaches examined demonstrated strong correlations with the experimental acidity values.

  12. Analysis of the role of Mycobacterium tuberculosis kasA gene mutations in isoniazid resistance.

    PubMed

    Sun, Y-J; Lee, A S G; Wong, S-Y; Paton, N I

    2007-08-01

    Previous studies have suggested that Mycobacterium tuberculosis kasA G312S and G269S gene mutations may represent sequence polymorphisms of the M. tuberculosis East-African-Indian (EAI) and T families, respectively, rather than relating to isoniazid resistance. The present study examined polymorphisms of these two codons in 98 drug-susceptible M. tuberculosis isolates (68 EAI and 30 T isolates). Twenty-eight isolates belonging to a sub-lineage of the EAI family had the kasA G312S mutation, but none of the 30 T isolates had the G269S mutation. The data suggest that the kasA G312S mutation is not related to isoniazid resistance, but represents a sequence polymorphism in a sub-lineage of the EAI family. PMID:17501974

  13. SRTM Colored and Shaded Topography: Haro and Kas Hills, India

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On January 26, 2001, the Kachchh region in western India suffered the most deadly earthquake in India's history. This shaded topography view of landforms northeast of the city of Bhuj depicts geologic structures that are of interest in the study the tectonic processes that may have led to that earthquake. However, preliminary field studies indicate that these structures are composed of Mesozoic rocks that are overlain by younger rocks showing little deformation. Thus these structures may be old, not actively growing, and not directly related to the recent earthquake.

    The Haro Hills are on the left and the Kas Hills are on the right. The Haro Hills are an 'anticline,' which is an upwardly convex elongated fold of layered rocks. In this view, the anticline is distinctly ringed by an erosion resistant layer of sandstone. The east-west orientation of the anticline may relate to the crustal compression that has occurred during India's northward movement toward, and collision with, Asia. In contrast, the largest of the Kas Hills appears to be a tilted (to the south) and faulted (on the north) block of layered rocks. Also seen here, the linear feature trending toward the southwest from the image center is an erosion-resistant 'dike,' which is an igneous intrusion into older 'host' rocks along a fault plane or other crack. These features are simple examples of how shaded topography can provide a direct input to geologic studies.

    In this image, colors show the elevation as measured by the Shuttle Radar Topography Mission (SRTM). Colors range from green at the lowest elevations, through yellow and red, to purple at the highest elevations. Elevations here range from near sea level to about 300 meters (about 1000 feet). Shading has been added, with illumination from the north (image top).

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same

  14. The protonation state of catalytic residues in the resting state of KasA revisited: detailed mechanism for the activation of KasA by its own substrate.

    PubMed

    Lee, Wook; Engels, Bernd

    2014-02-11

    Mycobacterium tuberculosis is the causative pathogen of tuberculosis, the second leading cause of death from an infectious disease globally. β-Ketoacyl ACP synthase I (KasA) is essential for the survival of M. tuberculosis, because it is one of the key enzymes in the biosynthetic pathway of mycolic acid, the building block of the cell wall in M. tuberculosis. To distinguish among the various suggested mechanisms of KasA that are based on different protonation states of the active site, we characterize its resting state by various theoretical approaches ranging from first-principle-based quantum mechanical/molecular mechanical molecular dynamics simulations (QM/MM MD) with large QM parts to force field-based MD and free energy perturbation computations. In contrast to a previous study that used less reliable semiempirical approaches in combination with smaller QM parts, our improved computations predict that the most important active site residues, Cys171 and His311, are neutral. Because the neutral catalytic residues are too unreactive to attack the substrate, the question of how their activation is achieved arises. Combining our computed results with structural information about the malonyl binding pocket, we devised a detailed model about the activation mechanism. A conformational change of Phe404 possibly triggered by the substrate is central for the activation because it switches KasA to the sufficiently reactive zwitterionic state. PMID:24479625

  15. Electrostatic Environment of Hemes in Proteins: pKas of Hydroxyl Ligands†

    PubMed Central

    Song, Yifan; Mao, Junjun; Gunner, M. R.

    2009-01-01

    The pKas of ferric aquo–heme and aquo–heme electrochemical midpoints (Ems) at pH 7 in sperm whale myoglobin, Aplysia myoblogin, hemoglobin I, heme oxygenase 1, horseradish peroxidase and cytochrome c oxidase were calculated with Multi-Conformation Continuum Electrostatics (MCCE). The pKas span 3.3 pH units from 7.6 in heme oxygenase 1 to 10.9 in peroxidase, and the Ems range from −250 mv in peroxidase to 125 mV in Aplysia myoglobin. Proteins with higher in situ ferric aquo–heme pKas tend to have lower Ems. Both changes arise from the protein stabilizing a positively charged heme. However, compared with values in solution, the protein shifts the aquo–heme Ems more than the pKas. Thus, the protein has a larger effective dielectric constant for the protonation reaction, showing that electron and proton transfers are coupled to different conformational changes that are captured in the MCCE analysis. The calculations reveal a breakdown in the classical continuum electrostatic analysis of pairwise interactions. Comparisons with DFT calculations show that Coulomb’s law overestimates the large unfavorable interactions between the ferric water–heme and positively charged groups facing the heme plane by as much as 60%. If interactions with CuB in cytochrome c oxidase and Arg 38 in horseradish peroxidase are not corrected, the pKa calculations are in error by as much as 6 pH units. With DFT corrected interactions calculated pKas and Ems differ from measured values by less than 1 pH unit or 35 mV, respectively. The in situ aquo–heme pKa is important for the function of cytochrome c oxidase since it helps to control the stoichiometry of proton uptake coupled to electron transfer PMID:16800621

  16. SRTM Stereo Pair: Haro and Kas Hills, India

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On January 26, 2001 the Kachchh region in western India suffered the most deadly earthquake in India's history. This stereoscopic view of landforms northeast of the city of Bhuj depicts geologic structures that are of interest in the study the tectonic processes that may have led to that earthquake. However, preliminary field studies indicate that these structures are composed of Mesozoic rocks that are overlain by younger rocks showing little deformation. Thus these structures may be old, not actively growing, and not directly related to the recent earthquake.

    The Haro Hills are on the left and the Kas Hills are on the right. The Haro Hills are an 'anticline,' which is an upwardly convex elongated fold of layered rocks. The anticline is distinctly ringed by an erosion resistant layer of sandstone. The east-west orientation of the anticline may relate to the crustal compression that has occurred during India's northward movement toward, and collision with, Asia. In contrast, the largest of the Kas Hills appears to be a tilted (to the south) and faulted (on the north) block of layered rocks. Also seen here, the curvilinear ridge trending toward the southwest from the image center is an erosion resistant 'dike,' which is an igneous intrusion into older 'host' rocks along a fault plane or other crack. The dike also appears to extend northeast from the image center as a dark line having very little topography. Its location between the tilted block and a smaller anticline to the north (directly east of the larger anticline) probably indicates that the dike fills the fault that separates these contrasting geologic structures. These features are simple examples of how digital elevation data can stereoscopically enhance satellite imagery to provide a direct input to geologic studies.

    This stereoscopic image was generated by draping a Landsat satellite image (taken just two weeks after the earthquake) over a preliminary Shuttle Radar Topography Mission (SRTM

  17. SRTM Stereo Pair: Haro and Kas Hills, India

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On January 26, 2001 the Kachchh region in western India suffered the most deadly earthquake in India's history. This stereoscopic view of landforms northeast of the city of Bhuj depicts geologic structures that are of interest in the study the tectonic processes that may have led to that earthquake. However, preliminary field studies indicate that these structures are composed of Mesozoic rocks that are overlain by younger rocks showing little deformation. Thus these structures may be old, not actively growing, and not directly related to the recent earthquake.

    The Haro Hills are on the left and the Kas Hills are on the right. The Haro Hills are an 'anticline,' which is an upwardly convex elongated fold of layered rocks. The anticline is distinctly ringed by an erosion resistant layer of sandstone. The east-west orientation of the anticline may relate to the crustal compression that has occurred during India's northward movement toward, and collision with, Asia. In contrast, the largest of the Kas Hills appears to be a tilted (to the south) and faulted (on the north) block of layered rocks. Also seen here, the curvilinear ridge trending toward the southwest from the image center is an erosion resistant 'dike,' which is an igneous intrusion into older 'host' rocks along a fault plane or other crack. The dike also appears to extend northeast from the image center as a dark line having very little topography. Its location between the tilted block and a smaller anticline to the north (directly east of the larger anticline) probably indicates that the dike fills the fault that separates these contrasting geologic structures. These features are simple examples of how digital elevation data can stereoscopically enhance satellite imagery to provide a direct input to geologic studies.

    This stereoscopic image was generated by draping a Landsat satellite image (taken just two weeks after the earthquake) over a preliminary Shuttle Radar Topography Mission (SRTM

  18. Changes in Deceased Donor Kidney Transplantation One Year After KAS Implementation.

    PubMed

    Stewart, D E; Kucheryavaya, A Y; Klassen, D K; Turgeon, N A; Formica, R N; Aeder, M I

    2016-06-01

    After over a decade of discussion, analysis, and consensus-building, a new kidney allocation system (KAS) was implemented on December 4, 2014. Key goals included improving longevity matching between donor kidneys and recipients and broadening access for historically disadvantaged subpopulations, in particular highly sensitized patients and those with an extended duration on dialysis but delayed referral for transplantation. To evaluate the early impact of KAS, we compared Organ Procurement and Transplantation Network data 1 year before versus after implementation. The distribution of transplants across many recipient characteristics has changed markedly and suggests that in many ways the new policy is achieving its goals. Transplants in which the donor and recipient age differed by more than 30 years declined by 23%. Initial, sharp increases in transplants were observed for Calculated Panel-Reactive Antibody 99-100% recipients and recipients with at least 10 years on dialysis, with a subsequent tapering of transplants to these groups suggesting bolus effects. Although KAS has arguably increased fairness in allocation, the potential costs of broadening access must be considered. Kidneys are more often being shipped over long distances, leading to increased cold ischemic times. Delayed graft function rates have increased, but 6-month graft survival rates have not changed significantly. PMID:26932731

  19. Requirement for kasB in Mycobacterium mycolic acid biosynthesis, cell wall impermeability and intracellular survival: implications for therapy.

    PubMed

    Gao, Lian-Yong; Laval, Francoise; Lawson, Elise H; Groger, Richard K; Woodruff, Andy; Morisaki, J Hiroshi; Cox, Jeffery S; Daffe, Mamadou; Brown, Eric J

    2003-09-01

    Mycobacterium tuberculosis infects one-third of the world's population and causes two million deaths annually. The unusually low permeability of its cell wall contributes to the ability of M. tuberculosis to grow within host macrophages, a property required for pathogenesis of infection. Mycobacterium marinum is an established model for discovering genes involved in mycobacterial infection. Mycobacterium marinum mutants with transposon insertions in the beta-ketoacyl-acyl carrier protein synthase B gene (kasB) grew poorly in macrophages, although growth in vitro was unaffected. Detailed analyses by thin-layer chromatography, nuclear magnetic resonance (NMR), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, infrared spectroscopy, and chemical degradations showed that the kasB mutants synthesize mycolic acids that are 2-4 carbons shorter than wild type; the defect was localized to the proximal portion of the meromycolate chain. In addition, these mutants showed a significant (approximately 30%) reduction in the abundance of keto-mycolates, with a slight compensatory increase of both alpha- and methoxy-mycolates. Despite these small changes in mycolate length and composition, the kasB mutants exhibited strikingly altered cell wall permeability, leading to a marked increase in susceptibility to lipophilic antibiotics and the host antimicrobial molecules defensin and lysozyme. The abnormalities of the kasB mutants were fully complemented by expressing M. tuberculosis kasB, but not by the closely related gene kasA. These studies identify kasB as a novel target for therapeutic intervention in mycobacterial diseases. PMID:12950920

  20. Overexpression of inhA, but not kasA, confers resistance to isoniazid and ethionamide in Mycobacterium smegmatis, M. bovis BCG and M. tuberculosis.

    PubMed

    Larsen, Michelle H; Vilchèze, Catherine; Kremer, Laurent; Besra, Gurdyal S; Parsons, Linda; Salfinger, Max; Heifets, Leonid; Hazbon, Manzour H; Alland, David; Sacchettini, James C; Jacobs, William R

    2002-10-01

    The inhA and kasA genes of Mycobacterium tuberculosis have each been proposed to encode the primary target of the antibiotic isoniazid (INH). Previous studies investigating whether overexpressed inhA or kasA could confer resistance to INH yielded disparate results. In this work, multicopy plasmids expressing either inhA or kasA genes were transformed into M. smegmatis, M. bovis BCG and three different M. tuberculosis strains. The resulting transformants, as well as previously published M. tuberculosis strains with multicopy inhA or kasAB plasmids, were tested for their resistance to INH, ethionamide (ETH) or thiolactomycin (TLM). Mycobacteria containing inhA plasmids uniformly exhibited 20-fold or greater increased resistance to INH and 10-fold or greater increased resistance to ETH. In contrast, the kasA plasmid conferred no increased resistance to INH or ETH in any of the five strains, but it did confer resistance to thiolactomycin, a known KasA inhibitor. INH is known to increase the expression of kasA in INH-susceptible M. tuberculosis strains. Using molecular beacons, quantified inhA and kasA mRNA levels showed that increased inhA mRNA levels corre--lated with INH resistance, whereas kasA mRNA levels did not. In summary, analysis of strains harbouring inhA or kasA plasmids yielded the same conclusion: overexpressed inhA, but not kasA, confers INH and ETH resistance to M. smegmatis, M. bovis BCG and M. tuberculosis. Therefore, InhA is the primary target of action of INH and ETH in all three species. PMID:12406221

  1. X-Ray Crystal Structure of Mycobacterium Tuberculosis β-Ketoacyl Acyl Carrier Protein Synthase II (mtKasB)

    PubMed Central

    Sridharan, Sudharsan; Wang, Lei; Brown, Alistair K.; Dover, Lynn G.; Kremer, Laurent; Besra, Gurdyal S.; Sacchettini, James C.

    2007-01-01

    Summary Mycolic acids are long chain α-alkyl branched, β-hydroxy fatty acids that represent a characteristic component of the Mycobacterium tuberculosis cell wall. Through their covalent attachment to peptidoglycan via an arabinogalactan polysaccharide, they provide the basis for an essential outer envelope membrane. Mycobacteria possess two fatty acid synthases (FAS); FAS-I carries out de novo synthesis of fatty acids while FAS-II is considered to elongate medium chain length fatty acyl primers to provide long chain (C56) precursors of mycolic acids. Here we report the crystal structure of Mycobacterium tuberculosis β-ketoacyl acyl carrier protein synthase (ACP) II mtKasB, a mycobacterial elongation condensing enzyme involved in FAS-II. This enzyme, along with the M. tuberculosis β-ketoacyl ACP synthase I mtKasA, catalyzes the Claisen-type condensation reaction responsible for fatty acyl elongation in FAS-II and are potential targets for development of novel anti-tubercular drugs. The crystal structure refined to 2.4 Å resolution revealed that, like other KAS-II enzymes, mtKasB adopts a thiolase fold but contains unique structural features in the capping region that may be crucial to its preference for longer fatty acyl chains than its counterparts from other bacteria. Modeling of mtKasA using the mtKasB structure as a template predicts the overall structures to be almost identical, but a larger entrance to the active site tunnel is envisaged that might contribute to the greater sensitivity of mtKasA to the inhibitor thiolactomycin (TLM). Modeling of TLM binding in mtKasB shows that the drug fits the active site poorly and results of enzyme inhibition assays using TLM analogues are wholly consistent with our structural observations. Consequently, the structure described here further highlights the potential of TLM as an anti-tubercular lead compound and will aid further exploration of the TLM scaffold towards the design of novel compounds which inhibit

  2. Elucidation of the protonation states of the catalytic residues in mtKasA: implications for inhibitor design.

    PubMed

    Lee, Wook; Luckner, Sylvia R; Kisker, Caroline; Tonge, Peter J; Engels, Bernd

    2011-06-28

    KasA (β-ketoacyl ACP synthase I) is involved in the biosynthetic pathway of mycolic acids, an essential component of the cell wall in Mycobacterium tuberculosis. It was shown that KasA is essential for the survival of the pathogen and thus could serve as a new drug target for the treatment of tuberculosis. The active site of KasA was previously characterized by X-ray crystallography. However, questions regarding the protonation state of specific amino acids, the orientation of the histidine groups within the active site, and additional conformers being accessible at ambient temperatures remain open and have to be addressed prior to the design of new inhibitors. We investigate the active site of KasA in this work by means of structural motifs and relative energies. Molecular dynamics (MD) simulations, free energy perturbation computations, and calculations employing the hybrid quantum mechanics/molecular mechanics (QM/MM) method made it possible to determine the protonation status and reveal important details about the catalytic mechanism of KasA. Additionally, we can rationalize the molecular basis for the acyl-transfer activity in the H311A mutant. Our data strongly suggest that inhibitors should be able to inhibit different protonation states because the enzyme can switch easily between a zwitterionic and neutral state. PMID:21615093

  3. New data on the structure of the Kas Block in the basement of the West Siberian Plate

    NASA Astrophysics Data System (ADS)

    Kheraskova, T. N.; Kaplan, S. A.; Bubnov, V. P.; Galuev, V. I.

    2013-03-01

    A new concept concerning the structure and stages of evolution of the Kas Block of the West Siberian Plate is stated in this paper. The Kas Block is traditionally considered to be a subsided western margin of the Siberian Platform. The new concept is based on the results of the interpretation of the geophysical data recently obtained along the reference and regional profiles in this territory. The geological interpretation of the deep dynamic sections obtained by reprocessing of the CDP seismic reflection records has been performed for the first time. The structural features of the Kas Block, as well as the character of its junction with the Siberian Platform and the Paleozoic framework, are discussed. The tectonic scheme of the territory and the scheme of the pre-Late Devonian surface of the Kas Block have been compiled. The Baikalian age of the basement of the Kas Block is substantiated. The Salairian allochthonous ophiolite-basalt tectonic nappe is localized for the first time within the sedimentary cover of the Kas Block. The available information allowed us to reconstruct the development of the western margin of the Siberian continent in the Riphean and Early Paleozoic before and after the Baikalian Orogeny, respectively. The informational background of the geological and geophysical interpretation involves the results of the CDP seismic reflection profiling, including the deep dynamic seismic sections and parameters of the P-wave velocities along the reference 1-SB seismic line and the regional Vostok 10, 12, 15, and 16 seismic lines; the results of the deep seismic and magnetotelluric soundings; the gravity measurements; the magnetic exploration; and the new coherent physical geological models.

  4. Crystal structures of Mycobacterium tuberculosis KasA show mode of action within cell wall biosynthesis and its inhibition by thiolactomycin.

    PubMed

    Luckner, Sylvia R; Machutta, Carl A; Tonge, Peter J; Kisker, Caroline

    2009-07-15

    Mycobacteria have a unique cell wall consisting of mycolic acids, very-long-chain lipids that provide protection and allow the bacteria to persist within human macrophages. Inhibition of cell wall biosynthesis is fatal for the organism and a starting point for the discovery and development of novel antibiotics. We determined the crystal structures of KasA, a key enzyme involved in the biosynthesis of long-chain fatty acids, in its apo-form and bound to the natural product inhibitor thiolactomycin. Detailed insights into the interaction of the inhibitor with KasA and the identification of a polyethylene glycol molecule that mimics a fatty acid substrate of approximately 40 carbon atoms length, represent the first atomic view of a mycobacterial enzyme involved in the synthesis of long-chain fatty acids and provide a robust platform for the development of novel thiolactomycin analogs with high affinity for KasA. PMID:19604480

  5. Single-Crystal Growth of Ba1-xKxFe2As2 by KAs Self-Flux Method

    NASA Astrophysics Data System (ADS)

    Kihou, Kunihiro; Saito, Taku; Fujita, Kay; Ishida, Shigeyuki; Nakajima, Masamichi; Horigane, Kazumasa; Fukazawa, Hideto; Kohori, Yoh; Uchida, Shin-ichi; Akimitsu, Jun; Iyo, Akira; Lee, Chul-Ho; Eisaki, Hiroshi

    2016-03-01

    Single crystals of Ba1-xKxFe2As2 with 0.15 ≤ x ≤ 1 have been successfully synthesized by a KAs self-flux method. The potassium (K) concentration x of the grown crystals was systematically changed by changing the mixing ratio of Ba to Fe in the starting materials. The crystals have flat surfaces corresponding to the crystallographic (001) planes, whose planar dimensions increase with decreasing thickness when x increases. The superconducting transition temperature systematically changes with x, ranging from 38 K at x = 0.4 to 3.4 K at x = 1.0, in good agreement with the results for polycrystalline samples.

  6. Molecular dynamics of Mycobacterium tuberculosis KasA: implications for inhibitor and substrate binding and consequences for drug design.

    PubMed

    Schaefer, Benjamin; Kisker, Caroline; Sotriffer, Christoph A

    2011-11-01

    Inhibition of the production of fatty acids as essential components of the mycobacterial cell wall has been an established way of fighting tuberculosis for decades. However, increasing resistances and an outdated medical treatment call for the validation of new targets involved in this crucial pathway. In this regard, the β-ketoacyl ACP synthase KasA is a promising enzyme. In this study, three molecular dynamics simulations based on the wildtype crystal structures of inhibitor bound and unbound KasA were performed in order to investigate the flexibility and conformational space of this target. We present an exhaustive analysis of the binding-site flexibility and representative pocket conformations that may serve as new starting points for structure-based drug design. We also revealed a mechanism which may account for the comparatively low binding affinity of thiolactomycin. Furthermore, we examined the behavior of water molecules within the binding pocket and provide recommendations how to handle them in the drug design process. Finally, we analyzed the dynamics of a channel that accommodates the long-chain fatty acid substrates and, thereby, propose a mechanism of substrate access to this channel and how products are most likely released. PMID:22076471

  7. Clarification on the decarboxylation mechanism in KasA based on the protonation state of key residues in the acyl-enzyme state.

    PubMed

    Lee, Wook; Engels, Bernd

    2013-07-11

    The β-ketoacyl ACP synthase I (KasA) is a promising drug target because it is essential for the survival of Mycobacterium tuberculosis , a causative agent of tuberculosis. It catalyzes a condensation reaction that comprises three steps. The resulting elongated acyl chains are subsequently needed for the cell wall construction. While the mechanism of the first step (acylation of Cys171 in the active site) is straightforward already, the second step (decarboxylation of malonyl substrate) has been controversial due to the difficulty in determining the correct protonation states of the involved residues (His311, His345, Lys340, Glu354). Available experimental data suggest three possible mechanisms which differ considerably. They are not consistent with each other because these studies could not be performed for KasA at the beginning of decarboxylation step (acyl-enzyme state of KasA). Instead, different mutants had to be used which are expected to resemble this situation. In this first computational study about this topic, we use the free energy perturbation (FEP) method to compute the relevant pKa values in the acyl-enzyme state of KasA and use molecular dynamics (MD) simulations to rationalize the results. Subsequent density functional theory (DFT)-based quantum mechanical/molecular mechanical (QM/MM) MD simulations and umbrella samplings have been used to disentangle the close relationships between the protonation states of the involved residues. By these simulations, we can address the preferred protonation states and roles of the residues involved in decarboxylation reaction, thereby suggesting the possible mechanism for the decarboxylation step. PMID:23768199

  8. Structural basis for the recognition of mycolic acid precursors by KasA, a condensing enzyme and drug target from Mycobacterium tuberculosis.

    PubMed

    Schiebel, Johannes; Kapilashrami, Kanishk; Fekete, Agnes; Bommineni, Gopal R; Schaefer, Christin M; Mueller, Martin J; Tonge, Peter J; Kisker, Caroline

    2013-11-22

    The survival of Mycobacterium tuberculosis depends on mycolic acids, very long α-alkyl-β-hydroxy fatty acids comprising 60-90 carbon atoms. However, despite considerable efforts, little is known about how enzymes involved in mycolic acid biosynthesis recognize and bind their hydrophobic fatty acyl substrates. The condensing enzyme KasA is pivotal for the synthesis of very long (C38-42) fatty acids, the precursors of mycolic acids. To probe the mechanism of substrate and inhibitor recognition by KasA, we determined the structure of this protein in complex with a mycobacterial phospholipid and with several thiolactomycin derivatives that were designed as substrate analogs. Our structures provide consecutive snapshots along the reaction coordinate for the enzyme-catalyzed reaction and support an induced fit mechanism in which a wide cavity is established through the concerted opening of three gatekeeping residues and several α-helices. The stepwise characterization of the binding process provides mechanistic insights into the induced fit recognition in this system and serves as an excellent foundation for the development of high affinity KasA inhibitors. PMID:24108128

  9. Structural Basis for the Recognition of Mycolic Acid Precursors by KasA, a Condensing Enzyme and Drug Target from Mycobacterium Tuberculosis *

    PubMed Central

    Schiebel, Johannes; Kapilashrami, Kanishk; Fekete, Agnes; Bommineni, Gopal R.; Schaefer, Christin M.; Mueller, Martin J.; Tonge, Peter J.; Kisker, Caroline

    2013-01-01

    The survival of Mycobacterium tuberculosis depends on mycolic acids, very long α-alkyl-β-hydroxy fatty acids comprising 60–90 carbon atoms. However, despite considerable efforts, little is known about how enzymes involved in mycolic acid biosynthesis recognize and bind their hydrophobic fatty acyl substrates. The condensing enzyme KasA is pivotal for the synthesis of very long (C38–42) fatty acids, the precursors of mycolic acids. To probe the mechanism of substrate and inhibitor recognition by KasA, we determined the structure of this protein in complex with a mycobacterial phospholipid and with several thiolactomycin derivatives that were designed as substrate analogs. Our structures provide consecutive snapshots along the reaction coordinate for the enzyme-catalyzed reaction and support an induced fit mechanism in which a wide cavity is established through the concerted opening of three gatekeeping residues and several α-helices. The stepwise characterization of the binding process provides mechanistic insights into the induced fit recognition in this system and serves as an excellent foundation for the development of high affinity KasA inhibitors. PMID:24108128

  10. pH-Dependent Conformational Changes in Proteins and Their Effect on Experimental pKas: The Case of Nitrophorin 4

    PubMed Central

    Di Russo, Natali V.; Estrin, Dario A.; Martí, Marcelo A.; Roitberg, Adrian E.

    2012-01-01

    The acid-base behavior of amino acids is an important subject of study due to their prominent role in enzyme catalysis, substrate binding and protein structure. Due to interactions with the protein environment, their pKas can be shifted from their solution values and, if a protein has two stable conformations, it is possible for a residue to have different “microscopic”, conformation-dependent pKa values. In those cases, interpretation of experimental measurements of the pKa is complicated by the coupling between pH, protonation state and protein conformation. We explored these issues using Nitrophorin 4 (NP4), a protein that releases NO in a pH sensitive manner. At pH 5.5 NP4 is in a closed conformation where NO is tightly bound, while at pH 7.5 Asp30 becomes deprotonated, causing the conformation to change to an open state from which NO can easily escape. Using constant pH molecular dynamics we found two distinct microscopic Asp30 pKas: 8.5 in the closed structure and 4.3 in the open structure. Using a four-state model, we then related the obtained microscopic values to the experimentally observed “apparent” pKa, obtaining a value of 6.5, in excellent agreement with experimental data. This value must be interpreted as the pH at which the closed to open population transition takes place. More generally, our results show that it is possible to relate microscopic structure dependent pKa values to experimentally observed ensemble dependent apparent pKas and that the insight gained in the relatively simple case of NP4 can be useful in several more complex cases involving a pH dependent transition, of great biochemical interest. PMID:23133364

  11. Thiolactomycin-based β-ketoacyl-AcpM synthase A (KasA) inhibitors: fragment-based inhibitor discovery using transient one-dimensional nuclear overhauser effect NMR spectroscopy.

    PubMed

    Kapilashrami, Kanishk; Bommineni, Gopal R; Machutta, Carl A; Kim, Pilho; Lai, Cheng-Tsung; Simmerling, Carlos; Picart, Francis; Tonge, Peter J

    2013-03-01

    Thiolactomycin (TLM) is a natural product inhibitor of KasA, the β-ketoacyl synthase A from Mycobacterium tuberculosis. To improve the affinity of TLM for KasA, a series of TLM analogs have been synthesized based on interligand NOEs between TLM and a pantetheine analog when both are bound simultaneously to the enzyme. Kinetic binding data reveal that position 3 of the thiolactone ring is a suitable position for elaboration of the TLM scaffold, and the structure-activity relationship studies provide information on the molecular features that govern time-dependent inhibition in this enzyme system. These experiments also exemplify the utility of transient one-dimensional NOE spectroscopy for obtaining interligand NOEs compared with traditional steady state two-dimensional NOESY spectroscopy. PMID:23306195

  12. [The characteristics of the sensitivity of Mycobacterium tuberculosis to rifampicin and isoniazid through determination of mutations in the genes rpoB, katG, inhA, oxyR, and kasA by different molecular biological assays].

    PubMed

    Skotnikova, O I; Galkina, K Iu; Nosova, E Iu; Krasnova, M A; Moroz, A M

    2005-01-01

    Two hundred and two patients with different forms of pulmonary tuberculosis were examined to study the characteristics of sensitivity with the signs of multidrug resistance to rifampicin and isoniazid, by using a microbiological assay of the absolute concentrations and determining mutations in the genes rpoB, katG, inhA, oxyR, and kasA, by employing different molecular biological assays. Mycobacterium tuberculosis (MBT) DNA was isolated from both a diagnostic material (such as sputum, bronchial secretion), and clinical MBT isolates. By showing a higher sensitivity and a higher specificity, as cultural techniques, molecular biological assays of MBT drug sensitivity in patients with tuberculosis were ascertained to accelerate its diagnosis until the patient was admitted to a clinic. PMID:16209020

  13. Development of Solar Powered Feeding Scheme for Wireless Sensor Networks in low Solar Density Conditions / Bezvadu Sensoru Tīklu Elektroapgādes Sistēmas Izstrāde, Kas Izmanto Saules Paneļus Un Darbojas Pazeminātas Saules Radiācijas Apstākļos

    NASA Astrophysics Data System (ADS)

    Kondratjevs, K.; Zabasta, A.; Selmanovs-Pless, V.

    2015-08-01

    In the recent years, there has been significant research focus on the safety and reliability of data harvesting and optimal energy consuming by wireless sensor network nodes. If external electrical power fails, the node needs to be able to send notifications to the utility demanding the use of backup energy strategies. The authors of the research offer an approach that can help to use PV panels as an alternative power source for WSN nodes in particular irradiation conditions. Survey and testing of the main types of PV panels offered on the market in conditions closed to real ones, in which WSN nodes are maintained, have been implemented. Based on the test results, maximum power control module parameters can be calculated in order to achieve the best effectiveness of the power control system for a selected type of PV panel or panel group. The novelty of the research is an approach that includes an original test bed design for PV testing, PV testing method and selection of design and MPP control module parameters, which ensure maximum effectiveness of WSN node power feeding. Pēdējos gados vairāki pētījumi ir veltīti problēmām, kas ir saistītas ar enerģijas patēriņa mazināšanu un efektīvu izmantošanu bezvadu sensoru tīklu mezglos. Kad sensors mezgls ir izsmēlis enerģijas krājumu, tas vairs nefunkcionē un atslēdzas no kopēja tīkla, kas var būtiski ietekmēt visa tīkla veiktspēju. Šī pētījuma mērķis ir izveidot barošanas vadības moduli, lai nodrošinātu stabilu elektroapgādes spriegumu autonomi strādājošiem radio signāla atkārtotājiem, sensoriem vai vārtejām, kas darbojas bezvadu sensoru tīklos. Pētījuma ietvaros izstrādāta metode saules paneļu kvalitatīvai salīdzināšanai starp tehnoloģijām vai savā starpā, izvērtējot to atbilstību mērķa pielietojumam. Izstrādātā metode sniedz iespēju veikt kontrolētus testus pie variējošiem, simulētiem gaismas apstākļiem, ļauj prognozēt enerģijas resursus

  14. Distributed Database Kriging for Adaptive Sampling (D2 KAS)

    NASA Astrophysics Data System (ADS)

    Roehm, Dominic; Pavel, Robert S.; Barros, Kipton; Rouet-Leduc, Bertrand; McPherson, Allen L.; Germann, Timothy C.; Junghans, Christoph

    2015-07-01

    We present an adaptive sampling method supplemented by a distributed database and a prediction method for multiscale simulations using the Heterogeneous Multiscale Method. A finite-volume scheme integrates the macro-scale conservation laws for elastodynamics, which are closed by momentum and energy fluxes evaluated at the micro-scale. In the original approach, molecular dynamics (MD) simulations are launched for every macro-scale volume element. Our adaptive sampling scheme replaces a large fraction of costly micro-scale MD simulations with fast table lookup and prediction. The cloud database Redis provides the plain table lookup, and with locality aware hashing we gather input data for our prediction scheme. For the latter we use kriging, which estimates an unknown value and its uncertainty (error) at a specific location in parameter space by using weighted averages of the neighboring points. We find that our adaptive scheme significantly improves simulation performance by a factor of 2.5-25, while retaining high accuracy for various choices of the algorithm parameters.

  15. Distributed database kriging for adaptive sampling (D²KAS)

    DOE PAGESBeta

    Roehm, Dominic; Pavel, Robert S.; Barros, Kipton; Rouet-Leduc, Bertrand; McPherson, Allen L.; Germann, Timothy C.; Junghans, Christoph

    2015-03-18

    We present an adaptive sampling method supplemented by a distributed database and a prediction method for multiscale simulations using the Heterogeneous Multiscale Method. A finite-volume scheme integrates the macro-scale conservation laws for elastodynamics, which are closed by momentum and energy fluxes evaluated at the micro-scale. In the original approach, molecular dynamics (MD) simulations are launched for every macro-scale volume element. Our adaptive sampling scheme replaces a large fraction of costly micro-scale MD simulations with fast table lookup and prediction. The cloud database Redis provides the plain table lookup, and with locality aware hashing we gather input data for our predictionmore » scheme. For the latter we use kriging, which estimates an unknown value and its uncertainty (error) at a specific location in parameter space by using weighted averages of the neighboring points. We find that our adaptive scheme significantly improves simulation performance by a factor of 2.5 to 25, while retaining high accuracy for various choices of the algorithm parameters.« less

  16. Distributed database kriging for adaptive sampling (D²KAS)

    SciTech Connect

    Roehm, Dominic; Pavel, Robert S.; Barros, Kipton; Rouet-Leduc, Bertrand; McPherson, Allen L.; Germann, Timothy C.; Junghans, Christoph

    2015-03-18

    We present an adaptive sampling method supplemented by a distributed database and a prediction method for multiscale simulations using the Heterogeneous Multiscale Method. A finite-volume scheme integrates the macro-scale conservation laws for elastodynamics, which are closed by momentum and energy fluxes evaluated at the micro-scale. In the original approach, molecular dynamics (MD) simulations are launched for every macro-scale volume element. Our adaptive sampling scheme replaces a large fraction of costly micro-scale MD simulations with fast table lookup and prediction. The cloud database Redis provides the plain table lookup, and with locality aware hashing we gather input data for our prediction scheme. For the latter we use kriging, which estimates an unknown value and its uncertainty (error) at a specific location in parameter space by using weighted averages of the neighboring points. We find that our adaptive scheme significantly improves simulation performance by a factor of 2.5 to 25, while retaining high accuracy for various choices of the algorithm parameters.

  17. Materials Data on KAs4IO6 (SG:191) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  18. Materials Data on KAsOF4 (SG:14) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2016-02-04

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  19. Materials Data on KAsSe2 (SG:9) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  20. Materials Data on KAsF6 (SG:148) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. MCCE analysis of the pKas of introduced buried acids and bases in staphylococcal nuclease.

    PubMed

    Gunner, M R; Zhu, Xuyu; Klein, Max C

    2011-12-01

    The pK(a)s of 96 acids and bases introduced into buried sites in the staphylococcal nuclease protein (SNase) were calculated using the multiconformation continuum electrostatics (MCCE) program and the results compared with experimental values. The pK(a)s are obtained by Monte Carlo sampling of coupled side chain protonation and position as a function of pH. The dependence of the results on the protein dielectric constant (ε(prot)) in the continuum electrostatics analysis and on the Lennard-Jones non-electrostatics parameters was evaluated. The pK(a)s of the introduced residues have a clear dependence on ε(prot,) whereas native ionizable residues do not. The native residues have electrostatic interactions with other residues in the protein favoring ionization, which are larger than the desolvation penalty favoring the neutral state. Increasing ε(prot) scales both terms, which for these residues leads to small changes in pK(a). The introduced residues have a larger desolvation penalty and negligible interactions with residues in the protein. For these residues, changing ε(prot) has a large influence on the calculated pK(a). An ε(prot) of 8-10 and a Lennard-Jones scaling of 0.25 is best here. The X-ray crystal structures of the mutated proteins are found to provide somewhat better results than calculations carried out on mutations made in silico. Initial relaxation of the in silico mutations by Gromacs and extensive side chain rotamer sampling within MCCE can significantly improve the match with experiment. PMID:21910138

  2. AIRID: an application of the KAS/Prospector expert system builder to airplane identification

    SciTech Connect

    Aldridge, J.P.

    1984-01-01

    The Knowledge Acquisition System/Prospector expert system building tool developed by SRI, International, has been used to construct an expert system to identify aircraft on the basis of observables such as wing shape, engine number/location, fuselage shape, and tail assembly shape. Additional detailed features are allowed to influence the identification as other favorable features. Constraints on the observations imposed by bad weather and distant observations have been included as contexts to the models. Models for Soviet and US fighter aircraft have been included. Inclusion of other types of aircraft such as bombers, transports, and reconnaissance craft is straightforward. Two models permit exploration of the interaction of semantic and taxonomic networks with the models. A full set of text data for fluid communication with the user has been included. The use of demons as triggered output responses to enhance utility to the user has been explored. This paper presents discussion of the ease of building the expert system using this powerful tool and problems encountered in the construction process.

  3. Simulating electrostatic energies in proteins: perspectives and some recent studies of pKas, redox, and other crucial functional properties.

    PubMed

    Warshel, Arieh; Dryga, Anatoly

    2011-12-01

    Electrostatic energies provide what is arguably the most effective tool for structure-function correlation of biological molecules. Here, we provide an overview of the current state-of-the-art simulations of electrostatic energies in macromolecules, emphasizing the microscopic perspective but also relating it to macroscopic approaches. We comment on the convergence issue and other problems of the microscopic models and the ways of keeping the microscopic physics while moving to semi-macroscopic directions. We discuss the nature of the protein dielectric "constants" reiterating our long-standing point that the dielectric "constants" in semi-macroscopic models depend on the definition and the specific treatment. The advances and the challenges in the field are illustrated considering different functional properties including pK(a)'s, redox potentials, ion and proton channels, enzyme catalysis, ligand binding, and protein stability. We emphasize the microscopic overcharging approach for studying pK(a) 's of internal groups in proteins and give a demonstration of power of this approach. We also emphasize recent advances in coarse grained models with a physically based electrostatic treatment and provide some examples including further directions in treating voltage activated ion channels. PMID:21910139

  4. DNA sequencing and transcriptional analysis of the kasugamycin biosynthetic gene cluster from Streptomyces kasugaensis M338-M1.

    PubMed

    Ikeno, Souichi; Aoki, Daisuke; Hamada, Masa; Hori, Makoto; Tsuchiya, Kayoko S

    2006-01-01

    Streptomyces kasugaensis M338-M1 produces the aminoglycoside antibiotic kasugamycin (KSM). We previously cloned, sequenced and characterized the KSM acetyltransferase, transporter, and some of the biosynthetic genes from this strain. To identify other potential genes in a chromosome walk experiment, a 6.8-kb EcoRI-PstI region immediately downstream from the KSM transporter genes was sequenced. Five open reading frames (designated as kasN, kasO, kasP, kasQ, kasR) and the 5' region of kasA were found in this region. The genes are apparently co-transcribed as bicistrons, all of which are co-directional except for the kasPQ transcript. Homology analysis of the deduced products of kasN, kasP, kasQ and kasR revealed similarities with known enzymes: KasN, D-amino acid oxidase from Pseudomonas aeruginosa (35% identity); KasP, F420-dependent H4MPT reductase from Streptomyces lavendulae (33% identity); KasQ, UDP-N-acetylglucosamine 2-epimerase from Streptomyces verticillus (45% identity); and KasR, NDP-hexose 3,4-dehydratase from Streptomyces cyanogenus (38% identity); respectively. A gel retardation assay showed that KasT, a putative pathway-specific regulator for this gene cluster, bound to the upstream region of kasN and to the intergenic region of kasQ-kasR, suggesting that the expression of these operons is under the control of the regulator protein. PMID:16568715

  5. High-Tc Nodeless s±-wave Superconductivity in (Y,La)FeAsO1-y with Tc=50K:As75-NMR Study

    NASA Astrophysics Data System (ADS)

    Mukuda, H.; Furukawa, S.; Kinouchi, H.; Yashima, M.; Kitaoka, Y.; Shirage, P. M.; Eisaki, H.; Iyo, A.

    2012-10-01

    We report on an As75-NMR study on the Fe-pnictide high-Tc superconductor Y0.95La0.05FeAsO1-y (Y0.95La0.051111) with Tc=50K that includes no magnetic rare-earth elements. The measurement of the nuclear-spin lattice-relaxation rate (751/T1) has revealed that the nodeless bulk superconductivity takes place at Tc=50K while antiferromagnetic spin fluctuations develop moderately in the normal state. These features are consistently described by the multiple fully gapped s±-wave model based on the Fermi-surface nesting. Incorporating the theory based on band calculations, we propose that the reason that Tc=50K in Y0.95La0.051111 is larger than Tc=28K in La1111 is that the Fermi-surface multiplicity is maximized, and hence the Fermi-surface nesting condition is better than that in La1111.

  6. Mycolic acid biosynthesis and enzymic characterization of the beta-ketoacyl-ACP synthase A-condensing enzyme from Mycobacterium tuberculosis.

    PubMed

    Kremer, Laurent; Dover, Lynn G; Carrère, Séverine; Nampoothiri, K Madhavan; Lesjean, Sarah; Brown, Alistair K; Brennan, Patrick J; Minnikin, David E; Locht, Camille; Besra, Gurdyal S

    2002-06-01

    Mycolic acids consist of long-chain alpha-alkyl-beta-hydroxy fatty acids that are produced by successive rounds of elongation catalysed by a type II fatty acid synthase (FAS-II). A key feature in the elongation process is the condensation of a two-carbon unit from malonyl-acyl-carrier protein (ACP) to a growing acyl-ACP chain catalysed by a beta-ketoacyl-ACP synthase (Kas). In the present study, we provide evidence that kasA from Mycobacterium tuberculosis encodes an enzyme that elongates in vivo the meromycolate chain, in both Mycobacterium smegmatis and Mycobacterium chelonae. We demonstrate that KasA belongs to the FAS-II system, which utilizes primarily palmitoyl-ACP rather than short-chain acyl-ACP primers. Furthermore, in an in vitro condensing assay using purified recombinant KasA, palmitoyl-AcpM and malonyl-AcpM, KasA was found to express Kas activity. Also, mutated KasA proteins, with mutation of Cys(171), His(311), Lys(340) and His(345) to Ala abrogated the condensation activity of KasA in vitro completely. Finally, purified KasA was highly sensitive to cerulenin, a well-known inhibitor of Kas, which may lead to the development of novel anti-mycobacterial drugs targeting KasA. PMID:12023885

  7. Structure of 3-oxoacyl-(acyl-carrier protein) synthase II from Thermus thermophilus HB8

    PubMed Central

    Bagautdinov, Bagautdin; Ukita, Yoko; Miyano, Masashi; Kunishima, Naoki

    2008-01-01

    The β-ketoacyl-(acyl carrier protein) synthases (β-keto-ACP synthases; KAS) catalyse the addition of two-carbon units to the growing acyl chain during the elongation phase of fatty-acid synthesis. As key regulators of bacterial fatty-acid synthesis, they are promising targets for the development of new antibacterial agents. The crystal structure of 3-oxoacyl-ACP synthase II from Thermus thermophilus HB8 (TtKAS II) has been solved by molecular replacement and refined at 2.0 Å resolution. The crystal is orthorhombic, space group P21212, with unit-cell parameters a = 72.07, b = 185.57, c = 62.52 Å, and contains one homodimer in the asymmetric unit. The subunits adopt the well known α-β-α-β-α thiolase fold that is common to ACP synthases. The structural and sequence similarities of TtKAS II to KAS I and KAS II enzymes of known structure from other sources support the hypothesis of comparable enzymatic activity. The dimeric state of TtKAS II is important to create each fatty-acid-binding pocket. Closer examination of KAS structures reveals that compared with other KAS structures in the apo form, the active site of TtKAS II is more accessible because of the ‘open’ conformation of the Phe396 side chain. PMID:18453702

  8. Structure of 3-oxoacyl-(acyl-carrier protein) synthase II from Thermus thermophilus HB8.

    PubMed

    Bagautdinov, Bagautdin; Ukita, Yoko; Miyano, Masashi; Kunishima, Naoki

    2008-05-01

    The beta-ketoacyl-(acyl carrier protein) synthases (beta-keto-ACP synthases; KAS) catalyse the addition of two-carbon units to the growing acyl chain during the elongation phase of fatty-acid synthesis. As key regulators of bacterial fatty-acid synthesis, they are promising targets for the development of new antibacterial agents. The crystal structure of 3-oxoacyl-ACP synthase II from Thermus thermophilus HB8 (TtKAS II) has been solved by molecular replacement and refined at 2.0 A resolution. The crystal is orthorhombic, space group P2(1)2(1)2, with unit-cell parameters a = 72.07, b = 185.57, c = 62.52 A, and contains one homodimer in the asymmetric unit. The subunits adopt the well known alpha-beta-alpha-beta-alpha thiolase fold that is common to ACP synthases. The structural and sequence similarities of TtKAS II to KAS I and KAS II enzymes of known structure from other sources support the hypothesis of comparable enzymatic activity. The dimeric state of TtKAS II is important to create each fatty-acid-binding pocket. Closer examination of KAS structures reveals that compared with other KAS structures in the apo form, the active site of TtKAS II is more accessible because of the ;open' conformation of the Phe396 side chain. PMID:18453702

  9. The Influences of Immigration on Health Information Seeking Behaviors among Korean Americans and Native Koreans

    ERIC Educational Resources Information Center

    Oh, Kyeung Mi; Zhou, Qiuping; Kreps, Gary; Kim, Wonsun

    2014-01-01

    Korean Americans (KAs) have low screening rates for cancer and are often not well informed about their chronic diseases. Reduced access to health-related information is one reason for gaps in knowledge and the widening health disparities among minority populations. However, little research exists about KAs' health information seeking…

  10. A Manifest Anxiety Scale from the MMPI-168

    ERIC Educational Resources Information Center

    King, M. G.; Campbell, I. M.

    1986-01-01

    Describes the KAS scale, a new composite anxiety scale that comprises items on the Minnesota Multiphasic Personality Inventory-168 (MMPI-168), a popular short form of the MMPI. Relevant normative statistics and the KAS scale relationship with other MMPI scales are discussed. (Author/KS)

  11. Groups of adjacent contour segments for object detection.

    PubMed

    Ferrari, V; Fevrier, L; Jurie, F; Schmid, C

    2008-01-01

    We present a family of scale-invariant local shape features formed by chains of k connected, roughly straight contour segments (kAS), and their use for object class detection. kAS are able to cleanly encode pure fragments of an object boundary, without including nearby clutter. Moreover, they offer an attractive compromise between information content and repeatability, and encompass a wide variety of local shape structures. We also define a translation and scale invariant descriptor encoding the geometric configuration of the segments within a kAS, making kAS easy to reuse in other frameworks, for example as a replacement or addition to interest points. Software for detecting and describing kAS is released on lear.inrialpes.fr/software. We demonstrate the high performance of kAS within a simple but powerful sliding-window object detection scheme. Through extensive evaluations, involving eight diverse object classes and more than 1400 images, we 1) study the evolution of performance as the degree of feature complexity k varies and determine the best degree; 2) show that kAS substantially outperform interest points for detecting shape-based classes; 3) compare our object detector to the recent, state-of-the-art system by Dalal and Triggs [4]. PMID:18000323

  12. Insights from computational analysis of full-length β-ketoacyl-[ACP] synthase-II cDNA isolated from American and African oil palms

    PubMed Central

    Bhore, Subhash J.; Cha, Thye S.; Amelia, Kassim; Shah, Farida H.

    2014-01-01

    Background: Palm oil derived from fruits (mesocarp) of African oil palm (Elaeis guineensis Jacq. Tenera) and American oil palm (E. oleifera) is important for food industry. Due to high yield, Elaeis guineensis (Tenera) is cultivated on commercial scale, though its oil contains high (~54%) level of saturated fatty acids. The rate-limiting activity of beta-ketoacyl-[ACP] synthase-II (KAS-II) is considered mainly responsible for the high (44%) level of palmitic acid (C16:0) in the oil obtained from E. guineensis. Objective: The objective of this study was to annotate KAS-II cDNA isolated from American and African oil palms. Materials and Methods: The full-length E. oleifera KAS-II (EoKAS-II) cDNA clone was isolated using random method of gene isolation. Whereas, the E. guineensis KAS-II (EgTKAS-II) cDNA was isolated using reverse transcriptase polymerase chain reaction (RT-PCR) technique; and missing ends were obtained by employing 5’and 3’ RACE technique. Results: The results show that EoKAS-II and EgTKAS-II open reading frames (ORFs) are of 1689 and 1721 bp in length, respectively. Further analysis of the both EoKAS-II and EgTKAS-II predicted protein illustrates that they contains conserved domains for ‘KAS-I and II’, ‘elongating’ condensing enzymes, ‘condensing enzymes super-family’, and ‘3-oxoacyl-[ACP] synthase II’. The predicted protein sequences shows 95% similarity with each other. Consecutively, the three active sites (Cys, His, and His) were identified in both proteins. However, difference in positions of two active Histidine (His) residues was noticed. Conclusion: These insights may serve as the foundation in understanding the variable activity of KAS-II in American and African oil palms; and cDNA clones could be useful in the genetic engineering of oil palms. PMID:24678202

  13. Structure of 3-oxoacyl-(acyl-carrier protein) synthase II from Thermus thermophilus HB8

    SciTech Connect

    Bagautdinov, Bagautdin Ukita, Yoko; Miyano, Masashi; Kunishima, Naoki

    2008-05-01

    The crystal structure of 3-oxoacyl-(acyl-carrier protein) synthase II from T. thermophilus HB8 has been determined at 2.0 Å resolution and compared with the structures of β-keto-ACP synthases from other sources. The β-ketoacyl-(acyl carrier protein) synthases (β-keto-ACP synthases; KAS) catalyse the addition of two-carbon units to the growing acyl chain during the elongation phase of fatty-acid synthesis. As key regulators of bacterial fatty-acid synthesis, they are promising targets for the development of new antibacterial agents. The crystal structure of 3-oxoacyl-ACP synthase II from Thermus thermophilus HB8 (TtKAS II) has been solved by molecular replacement and refined at 2.0 Å resolution. The crystal is orthorhombic, space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 72.07, b = 185.57, c = 62.52 Å, and contains one homodimer in the asymmetric unit. The subunits adopt the well known α-β-α-β-α thiolase fold that is common to ACP synthases. The structural and sequence similarities of TtKAS II to KAS I and KAS II enzymes of known structure from other sources support the hypothesis of comparable enzymatic activity. The dimeric state of TtKAS II is important to create each fatty-acid-binding pocket. Closer examination of KAS structures reveals that compared with other KAS structures in the apo form, the active site of TtKAS II is more accessible because of the ‘open’ conformation of the Phe396 side chain.

  14. Allelic variation in the vacuolar TPK1 channel affects its calcium dependence and may impact on stomatal conductance.

    PubMed

    Hartley, Tom N; Maathuis, Frans J M

    2016-01-01

    Natural variation can be exploited to identify allelic variants of proteins. In this study, patch clamp was used to determine transport properties of two AtTPK1 alleles from Landsberg and Kas-2 ecotypes. No difference in conductance or ion selectivity was observed but the Kas version of TPK1 showed different Ca(2+) dependence in its open probability compared to Ler. Leaves from Kas showed lower rates of water loss than those of Ler, in either the absence or presence of ABA, an observation that is consistent with higher TPK1 channel activity at comparable cytoplasmic Ca(2+) concentrations. A model that explains the results is presented. PMID:26765783

  15. Quantitative proteomic analysis of drug-induced changes in mycobacteria.

    PubMed

    Hughes, Minerva A; Silva, Jeffrey C; Geromanos, Scott J; Townsend, Craig A

    2006-01-01

    A new approach for qualitative and quantitative proteomic analysis using capillary liquid chromatography and mass spectrometry to study the protein expression response in mycobacteria following isoniazid treatment is discussed. In keeping with known effects on the fatty acid synthase II pathway, proteins encoded by the kas operon (AcpM, KasA, KasB, Accd6) were significantly overexpressed, as were those involved in iron metabolism and cell division suggesting a complex interplay of metabolic events leading to cell death. PMID:16396495

  16. Caspofungin Injection

    MedlinePlus

    (kas'' poe fun' jin) ... hour once a day. The length of your treatment depends on your general health, the type of ... doctor about how you are feeling during your treatment.You should begin to feel better during the ...

  17. 50 CFR Table 14a to Part 679 - Port of Landing Codes 1, Alaska

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Kake 137 KAK Kaltag 310 KAL Kasilof 138 KAS Kenai 139 KEN Kenai River 139 KEN Ketchikan 141 KTN King... report a landing at an Alaska location not currently assigned a location code number, use “Other...

  18. 50 CFR Table 14a to Part 679 - Port of Landing Codes 1, Alaska

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Kake 137 KAK Kaltag 310 KAL Kasilof 138 KAS Kenai 139 KEN Kenai River 139 KEN Ketchikan 141 KTN King... report a landing at an Alaska location not currently assigned a location code number, use “Other...

  19. 50 CFR Table 14a to Part 679 - Port of Landing Codes 1, Alaska

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Kake 137 KAK Kaltag 310 KAL Kasilof 138 KAS Kenai 139 KEN Kenai River 139 KEN Ketchikan 141 KTN King... report a landing at an Alaska location not currently assigned a location code number, use “Other...

  20. 50 CFR Table 14a to Part 679 - Port of Landing Codes 1, Alaska

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Kake 137 KAK Kaltag 310 KAL Kasilof 138 KAS Kenai 139 KEN Kenai River 139 KEN Ketchikan 141 KTN King... report a landing at an Alaska location not currently assigned a location code number, use “Other...

  1. 50 CFR Table 14a to Part 679 - Port of Landing Codes 1, Alaska

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Kake 137 KAK Kaltag 310 KAL Kasilof 138 KAS Kenai 139 KEN Kenai River 139 KEN Ketchikan 141 KTN King... report a landing at an Alaska location not currently assigned a location code number, use “Other...

  2. Early Changes in Kidney Distribution under the New Allocation System.

    PubMed

    Massie, Allan B; Luo, Xun; Lonze, Bonnie E; Desai, Niraj M; Bingaman, Adam W; Cooper, Matthew; Segev, Dorry L

    2016-08-01

    The Kidney Allocation System (KAS), a major change to deceased donor kidney allocation, was implemented in December 2014. Goals of KAS included directing the highest-quality organs to younger/healthier recipients and increasing access to deceased donor kidney transplantation (DDKT) for highly sensitized patients and racial/ethnic minorities. Using national registry data, we compared kidney distribution, DDKT rates for waitlist registrants, and recipient characteristics between January 1, 2013, and December 3, 2014 (pre-KAS) with those between December 4, 2014, and August 31, 2015 (post-KAS). Regional imports increased from 8.8% pre-KAS to 12.5% post-KAS; national imports increased from 12.7% pre-KAS to 19.1% post-KAS (P<0.001). The proportion of recipients >30 years older than their donor decreased from 19.4% to 15.0% (P<0.001). The proportion of recipients with calculated panel-reactive antibody =100 increased from 1.0% to 10.3% (P<0.001). Overall DDKT rate did not change as modeled using exponential regression adjusting for candidate characteristics (P=0.07). However, DDKT rate (incidence rate ratio, 95% confidence interval) increased for black (1.19; 1.13 to 1.25) and Hispanic (1.13; 1.05 to 1.20) candidates and for candidates aged 18-40 (1.47; 1.38 to 1.57), but declined for candidates aged >50 (0.93; 0.87 to 0.98 for aged 51-60 and 0.90; 0.85 to 0.96 for aged >70). Delayed graft function in transplant recipients increased from 24.8% pre-KAS to 29.9% post-KAS (P<0.001). Thus, in the first 9 months under KAS, access to DDKT improved for minorities, younger candidates, and highly sensitized patients, but declined for older candidates. Delayed graft function increased substantially, possibly suggesting poorer long-term outcomes. PMID:26677865

  3. The influences of immigration on health information seeking behaviors among Korean Americans and Native Koreans.

    PubMed

    Oh, Kyeung Mi; Zhou, Qiuping Pearl; Kreps, Gary; Kim, Wonsun

    2014-04-01

    Korean Americans (KAs) have low screening rates for cancer and are often not well informed about their chronic diseases. Reduced access to health-related information is one reason for gaps in knowledge and the widening health disparities among minority populations. However, little research exists about KAs' health information seeking behaviors. Guided by the Structural Influence Model, this study examines the influence of immigration status on KAs' trust in health information sources and health information seeking behaviors. Cross-sectional surveys were conducted in the Washington, D.C., metropolitan area as well as in the Gwangju metropolitan city in South Korea during 2006-2007. Two hundred and fifty-four KAs and 208 native Koreans who were 40 years of age or older completed the surveys. When comparing native Koreans to KAs, we found KAs were 3 times more likely to trust health information from newspapers or magazines (odds ratio [OR] = 3.13; 95% confidence interval [CI] = 1.49-6.54) and 11 times more likely to read the health sections of newspapers or magazines (OR = 11.35; 95% CI = 3.92-32.91) in multivariate adjusted models. However, they were less likely to look for health information from TV (OR = 0.29; 95% CI = 0.12-0.72) than native Koreans. Our results indicate that immigration status has profound influences on KAs' health information seeking behaviors. Increasing the availability of reliable and valid health information from printed Korean language magazines or newspapers could have a positive influence on increasing awareness and promoting screening behaviors among KAs. PMID:23943681

  4. Retroactive application of the new kidney allocation system to renal transplants performed in the ECD/SCD era.

    PubMed

    Ramanathan, Rajesh; Gupta, Gaurav; Kim, Joohyun; Quinn, Keri; Behnke, Martha; Kang, Le; Sharma, Amit

    2015-12-01

    The kidney allocation system (KAS) aims to improve deceased donor kidney transplant outcomes by matching of donor allografts and kidney recipients using the kidney donor risk index (KDRI) and recipient estimated post-transplant survival (EPTS) indices. In this single-center study, KAS was retroactively applied to 573 adult deceased donor kidney transplants (2004-2012) performed in the extended criteria/standard criteria donor (ECD/SCD) era. Donor KDRI and recipient EPTS were calculated, and transplants were analyzed to identify KAS fits. These were defined as allocation of top 20% allografts to top 20% recipients and bottom 80% allografts to bottom 80% recipients. On retroactive calculation, 70.2% of all transplants fit the KAS. Transplants that fit the KAS had inferior 1- and 5-yr patient survival (95.5% vs. 98.8%, p = 0.048, and 83.4% vs. 91.7%, p = 0.018) and similar 1- and 5-yr graft survival compared to transplants that did not fit the KAS (91.3% vs. 94.1%, p = 0.276, and 72.7% vs. 73.9%, p = 0.561). While EPTS correlated with recipient survival (HR = 2.96, p < 0.001), KDRI correlated with both recipient (HR = 3.56, p < 0.001) and graft survival (HR = 3.23, p < 0.001). Overall, retroactive application of the KAS to transplants performed in the ECD/SCD era did not identify superior patient survival for kidneys allocated in accordance with the KAS. PMID:26436727

  5. A single membrane-bound enzyme catalyzes the conversion of 2,5-diketo-d-gluconate to 4-keto-d-arabonate in d-glucose oxidative fermentation by Gluconobacter oxydans NBRC 3292.

    PubMed

    Tazoe, Masaaki; Oishi, Hiromi; Kobayashi, Setsuko; Hoshino, Tatsuo

    2016-08-01

    4-Keto-d-arabonate synthase (4KAS), which converts 2,5-diketo-d-gluconate (DKGA) to 4-keto-d-arabonate (4KA) in d-glucose oxidative fermentation by some acetic acid bacteria, was solubilized from the Gluconobacter oxydans NBRC 3292 cytoplasmic membrane, and purified in an electrophoretically homogenous state. A single membrane-bound enzyme was found to catalyze the conversion from DKGA to 4KA. The 92-kDa 4KAS was a homodimeric protein not requiring O2 or a cofactor for the conversion, but was stimulated by Mn(2+). N-terminal amino acid sequencing of 4KAS, followed by gene homology search indicated a 1,197-bp open reading frame (ORF), corresponding to the GLS_c04240 locus, GenBank accession No. CP004373, encoding a 398-amino acid protein with a calculated molecular weight of 42,818 Da. An Escherichia coli transformant with the 4kas plasmid exhibited 4KAS activity. Furthermore, overexpressed recombinant 4KAS was purified in an electrophoretically homogenous state and had the same molecular size as the natural enzyme. PMID:27010909

  6. 3-Ketoacyl-acyl carrier protein synthase III from spinach (Spinacia oleracea) is not similar to other condensing enzymes of fatty acid synthase.

    PubMed Central

    Tai, H; Jaworski, J G

    1993-01-01

    A cDNA clone encoding spinach (Spinacia oleracea) 3-ketoacyl-acyl carrier protein synthase III (KAS III), which catalyzes the initial condensing reaction in fatty acid biosynthesis, was isolated. Based on the amino acid sequence of tryptic digests of purified spinach KAS III, degenerate polymerase chain reaction (PCR) primers were designed and used to amplify a 612-bp fragment from first-strand cDNA of spinach leaf RNA. A root cDNA library was probed with the PCR fragment, and a 1920-bp clone was isolated. Its deduced amino acid sequence matched the sequences of the tryptic digests obtained from the purified KAS III. Northern analysis confirmed that it was expressed in both leaf and root. The clone contained a 1218-bp open reading frame coding for 405 amino acids. The identity of the clone was confirmed by expression in Escherichia coli BL 21 as a glutathione S-transferase fusion protein. The deduced amino acid sequence was 48 and 45% identical with the putative KAS III of Porphyra umbilicalis and KAS III of E. coli, respectively. It also had a strong local homology to the plant chalcone synthases but had little homology with other KAS isoforms from plants, bacteria, or animals. PMID:8290632

  7. Expression of ABCB6 is related to resistance to 5-FU, SN-38 and vincristine.

    PubMed

    Minami, Kentaro; Kamijo, Youhei; Nishizawa, Yukihiko; Tabata, Sho; Horikuchi, Fumito; Yamamoto, Masatatsu; Kawahara, Kohich; Shinsato, Yoshinari; Tachiwada, Tokushi; Chen, Zhe-Sheng; Tsujikawa, Kazutake; Nakagawa, Masayuki; Seki, Naohiko; Akiyama, Shin-Ichi; Arima, Kazunari; Takeda, Yasuo; Furukawa, Tatsuhiko

    2014-09-01

    A previously established arsenite-resistant cell line, KAS, is also resistant to a variety of anticancer drugs. In order to understand responsible molecules for the multidrug resistance phenotype of KAS cells, we examined the expressions of ATP-binding cassette (ABC) transporters and found that the ABCB6 and ABCC1/ multidrug resistance protein 1 (ABCC1/MRP1) were increased. ABCC1/MRP1 was not completely responsible for the drug resistance spectrum of KAS cells and several reports have suggested that ABCB6 is related to anticancer drug and metal resistance. We, therefore, established and examined ABCB6-expressing KB cells and ABCB6-knockdown KAS cells. ABCB6 expression enhanced resistance to 5-fluorouracil (5-FU), SN-38 and vincristine (Vcr) but not to arsenite. Conversely, down-regulation of ABCB6 in KAS cells increased the sensitivity of KAS cells to 5-FU, SN-38 and Vcr, but not to arsenite. Our findings suggest that ABCB6 is involved in 5-FU, SN-38 and Vcr resistance. PMID:25202056

  8. The condensing activities of the Mycobacterium tuberculosis type II fatty acid synthase are differentially regulated by phosphorylation.

    PubMed

    Molle, Virginie; Brown, Alistair K; Besra, Gurdyal S; Cozzone, Alain J; Kremer, Laurent

    2006-10-01

    Phosphorylation of proteins by Ser/Thr protein kinases (STPKs) has recently become of major physiological importance because of its possible involvement in virulence of bacterial pathogens. Although Mycobacterium tuberculosis has eleven STPKs, the nature and function of the substrates of these enzymes remain largely unknown. In this work, we have identified for the first time STPK substrates in M. tuberculosis forming part of the type II fatty acid synthase (FAS-II) system involved in mycolic acid biosynthesis: the malonyl-CoA::AcpM transacylase mtFabD, and the beta-ketoacyl AcpM synthases KasA and KasB. All three enzymes were phosphorylated in vitro by different kinases, suggesting a complex network of interactions between STPKs and these substrates. In addition, both KasA and KasB were efficiently phosphorylated in M. bovis BCG each at different sites and could be dephosphorylated by the M. tuberculosis Ser/Thr phosphatase PstP. Enzymatic studies revealed that, whereas phosphorylation decreases the activity of KasA in the elongation process of long chain fatty acids synthesis, this modification enhances that of KasB. Such a differential effect of phosphorylation may represent an unusual mechanism of FAS-II system regulation, allowing pathogenic mycobacteria to produce full-length mycolates, which are required for adaptation and intracellular survival in macrophages. PMID:16873379

  9. Keto Amphetamine Toxicity—Focus on the Redox Reactivity of the Cathinone Designer Drug Mephedrone

    PubMed Central

    den Hollander, Bjørnar; Sundström, Mira; Pelander, Anna; Ojanperä, Ilkka; Mervaala, Eero; Korpi, Esa Risto; Kankuri, Esko

    2014-01-01

    The β-keto amphetamine (cathinone, β-KA) designer drugs such as mephedrone (4-methylmethcathinone, 4-MMC) show a large degree of structural similarity to amphetamines like methamphetamine (METH). However, little is currently known about whether these substances also share the potential neurotoxic properties of their non-keto amphetamine counterparts, or what mechanisms could be involved. Here, we evaluate the cytotoxicity of β-KAs in SH-SY5Y cells using lactate dehydrogenase (LDH) assays, assess the redox potential of a range of β-KAs and non-keto amphetamines using the sensitive redox indicator 2-(4-Iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium (WST-1), and explore the effect of 4-MMC on the formation of protein adducts using ultra-high performance liquid chromatography/high-resolution time-of-flight mass spectrometry (UHPLC-HR-TOFMS) and on the mitochondrial respiratory chain using high-resolution respirometry. We show that treatment with β-KAs increases LDH release. Further, we demonstrate that even under physiological pH, β-KAs are effective and selective—as compared with their non-keto analogues—reductants in the presence of electron acceptors. Increased pH (range 7.6–8.0) greatly enhanced the reactivity up to sixfold. We found no evidence of protein adduct formation, suggesting the reactivity is due to direct electron transfer by the β-KAs. Finally, we show that 4-MMC and METH produce dissimilar effects on the respiratory chain. Our results indicate that β-KAs such as 4-MMC possess cytotoxic properties in vitro. Furthermore, in the presence of an electron-accepting redox partner, the ketone moiety of β-KAs is vital for pH-dependent redox reactivity. Further work is needed to establish the importance of β-KA redox properties and its potential toxicological importance in vivo. PMID:24913801

  10. 3D geological modeling of the Kasserine Aquifer System, Central Tunisia: New insights into aquifer-geometry and interconnections for a better assessment of groundwater resources

    NASA Astrophysics Data System (ADS)

    Hassen, Imen; Gibson, Helen; Hamzaoui-Azaza, Fadoua; Negro, François; Rachid, Khanfir; Bouhlila, Rachida

    2016-08-01

    The challenge of this study was to create a 3D geological and structural model of the Kasserine Aquifer System (KAS) in central Tunisia and its natural extension into north-east Algeria. This was achieved using an implicit 3D method, which honors prior geological data for both formation boundaries and faults. A current model is presented which provides defendable predictions for the spatial distribution of geology and water resources in aquifers throughout the model-domain. This work has allowed validation of regional scale geology and fault networks in the KAS, and has facilitated the first-ever estimations of groundwater resources in this region by a 3D method. The model enables a preliminary assessment of the hydraulic significance of the major faults by evaluating their influence and role on groundwater flow within and between four compartments of the multi-layered, KAS hydrogeological system. Thus a representative hydrogeological model of the study area is constructed. The possible dual nature of faults in the KAS is discussed in the context that some faults appear to be acting both as barriers to horizontal groundwater flow, and simultaneously as conduits for vertical flow. Also discussed is the possibility that two flow directions occur within the KAS, at a small syncline area of near Feriana. In summary, this work evaluates the influence of aquifer connectivity and the role of faults and geology in groundwater flow within the KAS aquifer system. The current KAS geological model can now be used to guide groundwater managers on the best placement for drilling to test and further refine the understanding of the groundwater system, including the faults connectivity. As more geological data become available, the current model can be easily edited and re-computed to provide an updated model ready for the next stage of investigation by numerical flow modeling.

  11. Isoniazid affects multiple components of the type II fatty acid synthase system of Mycobacterium tuberculosis.

    PubMed

    Slayden, R A; Lee, R E; Barry, C E

    2000-11-01

    Genetic and biochemical evidence has implicated two different target enzymes for isoniazid (INH) within the unique type II fatty acid synthase (FAS) system involved in the production of mycolic acids. These two components are an enoyl acyl carrier protein (ACP) reductase, InhA, and a beta-ketoacyl-ACP synthase, KasA. We compared the consequences of INH treatment of Mycobacterium tuberculosis (MTB) with two inhibitors having well-defined targets: triclosan (TRC), which inhibits InhA; and thiolactomycin (TLM), which inhibits KasA. INH and TLM, but not TRC, upregulate the expression of an operon containing five FAS II components, including kasA and acpM. Although all three compounds inhibit mycolic acid synthesis, treatment with INH and TLM, but not with TRC, results in the accumulation of ACP-bound lipid precursors to mycolic acids that were 26 carbons long and fully saturated. TLM-resistant mutants of MTB were more cross-resistant to INH than TRC-resistant mutants. Overexpression of KasA conferred more resistance to TLM and INH than to TRC. Overexpression of InhA conferred more resistance to TRC than to INH and TLM. Co-overexpression of both InhA and KasA resulted in strongly enhanced levels of INH resistance, in addition to cross-resistance to both TLM and TRC. These results suggest that these components of the FAS II complex are not independently regulated and that alterations in the expression level of InhA affect expression levels of KasA. Nonetheless, INH appeared to resemble TLM more closely in overall mode of action, and KasA levels appeared to be tightly correlated with INH sensitivity. PMID:11069675

  12. The supportive effect of supplementation with α-keto acids on physical training in type 2 diabetes mellitus.

    PubMed

    Liu, Y; Spreng, T; Lehr, M; Yang, B; Karau, A; Gebhardt, H; Steinacker, J M

    2015-07-01

    The maintenance of physical activity is crucial for the prevention and management of type 2 diabetes (T2D), and exercise induced changes including production of metabolites like ammonia can result in fatigue and exercise intolerance. Nutritional supplements may serve as an effective measure in supporting patients undergoing physical training by acting on their metabolism. This study investigates the effects of supplementation with α-keto acids (KAS) on exercise tolerance and glucose control in T2D patients. In a double-blind, placebo-controlled, randomized study 28 T2D patients underwent 6 weeks training on a cycle ergometer while they were supplemented with either a placebo or KAS (0.2 g kg(-1) body weight each day). The weekly training volume, power output at maximum and lactic threshold, leg muscle torque, the plasma concentration and 8 h urinary discharge of glucose, ammonia and urea were determined before and after the training as well as after one week of recovery. With KAS the patients did significantly more voluntary exercise (213 vs. 62 min, P < 0.01), reached a higher VO2max (27.3 vs. 24.8 ml min(-1) kg(-1)), higher power output (224 vs. 193 watts, P < 0.05) and greater endurance capacity (108 vs. 96 watts at lactic threshold, P < 0.05). Although the patients without KAS improved their glucose control after the training (P < 0.05), this effect could not be maintained after recovery as it was in the KAS group, where there was a prolonged benefit in glucose control. KAS also affected the ammonia and urea metabolism. KAS delivered supportive effects on the physical training along with a prolonged benefit in glucose control in T2D patients. PMID:26068548

  13. Effect of a Multi-Level Education Intervention Model on Knowledge and Attitudes of Accidental Injuries in Rural Children in Zunyi, Southwest China

    PubMed Central

    Cao, Bo-Ling; Shi, Xiu-Quan; Qi, Yong-Hong; Hui, Ya; Yang, Hua-Jun; Shi, Shang-Peng; Luo, Li-Rong; Zhang, Hong; Wang, Xin; Yang, Ying-Ping

    2015-01-01

    Objective: To explore the effect of a school-family-individual (SFI) multi-level education intervention model on knowledge and attitudes about accidental injuries among school-aged children to improve injury prevention strategies and reduce the incidence of pediatric injuries. Methods: The random sample of rural school-aged children were recruited by using a multistage, stratified, cluster sampling method in Zunyi, Southwest China from 2012 to 2014, and 2342 children were randomly divided into intervention and control groups. Then children answered a baseline survey to collect knowledge and attitude scores (KAS) of accidental injuries. In the intervention group, children, their parents/guardians and the school received a SFI multi-level education intervention, which included a children’s injury-prevention poster at schools, an open letter about security instruction for parents/guardians and multiple-media health education (Microsoft PowerPoint lectures, videos, handbooks, etc.) to children. Children in the control group were given only handbook education. After 16 months, children answered a follow-up survey to collect data on accidental injury types and accidental injury-related KAS for comparing the intervention and control groups and baseline and follow-up data. Results: The distribution of gender was not significantly different while age was different between the baseline and follow-up survey. At baseline, the mean KAS was lower for the intervention than control group (15.37 ± 3.40 and 18.35 ± 5.01; p < 0.001). At follow-up, the mean KAS was higher for the intervention than control group (21.16 ± 3.05 and 20.02 ± 3.40; p < 0.001). The increase in KAS in the intervention and control groups was significant (p < 0.001; KAS: 5.79 vs. 1.67) and suggested that children’s injury-related KAS improved in the intervention group. Moreover, the KAS between the groups differed for most subtypes of incidental injuries (based on International Classification of

  14. Diversion of phagosome trafficking by pathogenic Rhodococcus equi depends on mycolic acid chain length.

    PubMed

    Sydor, Tobias; von Bargen, Kristine; Hsu, Fong-Fu; Huth, Gitta; Holst, Otto; Wohlmann, Jens; Becken, Ulrike; Dykstra, Tobias; Söhl, Kristina; Lindner, Buko; Prescott, John F; Schaible, Ulrich E; Utermöhlen, Olaf; Haas, Albert

    2013-03-01

    Rhodococcus equi is a close relative of Mycobacterium spp. and a facultative intracellular pathogen which arrests phagosome maturation in macrophages before the late endocytic stage. We have screened a transposon mutant library of R. equi for mutants with decreased capability to prevent phagolysosome formation. This screen yielded a mutant in the gene for β-ketoacyl-(acyl carrier protein)-synthase A (KasA), a key enzyme of the long-chain mycolic acid synthesizing FAS-II system. The longest kasA mutant mycolic acid chains were 10 carbon units shorter than those of wild-type bacteria. Coating of non-pathogenic E. coli with purified wild-type trehalose dimycolate reduced phagolysosome formation substantially which was not the case with shorter kasA mutant-derived trehalose dimycolate. The mutant was moderately attenuated in macrophages and in a mouse infection model, but was fully cytotoxic.Whereas loss of KasA is lethal in mycobacteria, R. equi kasA mutant multiplication in broth was normal proving that long-chain mycolic acid compounds are not necessarily required for cellular integrity and viability of the bacteria that typically produce them. This study demonstrates a central role of mycolic acid chain length in diversion of trafficking by R. equi. PMID:23078612

  15. Genes involved in forebrain development in the zebrafish, Danio rerio.

    PubMed

    Heisenberg, C P; Brand, M; Jiang, Y J; Warga, R M; Beuchle, D; van Eeden, F J; Furutani-Seiki, M; Granato, M; Haffter, P; Hammerschmidt, M; Kane, D A; Kelsh, R N; Mullins, M C; Odenthal, J; Nusslein-Volhard, C

    1996-12-01

    We identified four zebrafish mutants with defects in forebrain induction and patterning during embryogenesis. The four mutants define three genes: masterblind (mbl), silberblick (slb), and knollnase (kas). In mbl embryos, the anterior forebrain acquires posterior forebrain characteristics: anterior structures such as the eyes, olfactory placodes and the telencephalon are missing, whereas the epiphysis located in the posterior forebrain is expanded. In slb embryos, the extension of the embryonic axis is initially delayed and eventually followed by a partial fusion of the eyes. Finally, in kas embryos, separation of the telencephalic primordia is incomplete and dorsal midline cells fail to form a differentiated roof plate. Analysis of the mutant phenotypes indicates that we have identified genes essential for the specification of the anterior forebrain (mbl), positioning of the eyes (slb) and differentiation of the roof plate (kas). In an appendix to this study we list mutants showing alterations in the size of the eyes and abnormal differentiation of the lenses. PMID:9007240

  16. Apamin-Sensitive Small Conductance Calcium-Activated Potassium Channels were Negatively Regulated by Captopril in Volume-Overload Heart Failure Rats.

    PubMed

    Hongyuan, Bai; Xin, Dong; Jingwen, Zhang; Li, Gao; Yajuan, Ni

    2016-08-01

    In heart failure (HF), the malignant arrhythmias occur frequently; a study demonstrated that upregulation of I KAS resulted in recurrent spontaneous ventricular fibrillation in HF. However, the regulation of SK channels was poorly understood. The activation of SK channels depended on [Ca(2+)]i and PP2A; studies suggested that angiotensin II can regulate them. So, we hypothesized that in HF, the excess of angiotensin may regulate the SK channels and result in the remodeling of SK channels. To test the hypothesis, we used volume-overload-induced HF rat model, treated with captopril, performed whole-cell patch clamp to record apamin-sensitive currents (I KAS), and I-V curve was studied. The sensitivity of I KAS to [Ca(2+)]i was also explored by setting various [Ca(2+)]i (10, 100, 500, 900, 1000, and 10,000 nM), and the steady-state Ca(2+) response of I KAS was attained and performed Hill fitting with the equation (y = 1/[1 + (EC50/x) (n) ]). Immunofluorescent staining, real-time PCR, Western blot were also carried out to furtherly investigate the underlying molecular mechanisms of the regulation. Captopril significantly decreased the mean density of I KAS when [Ca(2+)]i was 500, 900, 1000, and 10000 nM. The Hill fitting showed significantly different EC50 values and the Hill coefficients and showed captopril significantly shifted rightward the steady-state Ca(2+) response of I KAS. The results of real-time PCR and Western blot demonstrated captopril decreased the mRNA and protein expression of SK3 channels. Captopril significantly downregulated the sensitivity of SK channels to [Ca(2+)]i and the SK3 channels expression in HF, and reversed the SK channels remodeling. PMID:26924798

  17. Keratoacanthoma and Keratoacanthoma-Like Squamous Cell Carcinoma: Similar Morphology but Different Pathogenesis.

    PubMed

    Watanabe, Isabela C; Magalhães, Renata F; de Moraes, Aparecida M; Stelini, Rafael F; Cintra, Geórgia F; Metze, Konradin; Cintra, Maria L

    2015-06-01

    Differential diagnosis between keratoacanthoma (KA) and squamous cell carcinoma (SCC) is difficult due to their similarities. The mechanisms that drive their distinct biological behavior are poorly understood. To investigate whether the assessment of microvessel density (MVD) could be helpful in KA and SCC differential diagnosis and to gain insight into the pathogenesis of KA-like neoplasms, we compared the density of CD105- and CD34-stained vessels in KAs and SCCs and their relation to the expression of the p53 oncoprotein and proliferation marker Ki67. This is an observational retrospective cohort study. Forty lesions with clinical appearance of KAs (29 KAs and 11 SCCs) entered the study. A biopsy was taken from each lesion at presentation and the natural clinical course was monitored for at least 1 month. Growing or minimally regressing lesions were submitted to complete surgical excision. The diagnoses were established on combined clinical, histological, and follow-up evaluations. The MVD and p53 or Ki67 expression in neoplastic cells were assessed through morphometry. The MVD did not show discriminating power between KAs and SCCs. The Ki67 proliferation rate was significantly higher in SCCs. Although neoangiogenesis (CD105-MVD) in KAs was associated with cell proliferation, in SCCs it was not. There was significant correlation between p53 expression and neoplasia size in SCCs but not in KAs. From our results, we may conclude that KA and SCC have similarities, as CD105- and CD34-MVD. However, the low Ki67 proliferation index and the positive correlation between Ki-67 index and neovascularization in KA suggest a dependence in neovascularization to grow in KA, pointing to involvement of distinct pathogenesis. PMID:26061320

  18. Keratoacanthoma and Keratoacanthoma-Like Squamous Cell Carcinoma

    PubMed Central

    Watanabe, Isabela C.; Magalhães, Renata F.; de Moraes, Aparecida M.; Stelini, Rafael F.; Cintra, Geórgia F.; Metze, Konradin; Cintra, Maria L.

    2015-01-01

    Abstract Differential diagnosis between keratoacanthoma (KA) and squamous cell carcinoma (SCC) is difficult due to their similarities. The mechanisms that drive their distinct biological behavior are poorly understood. To investigate whether the assessment of microvessel density (MVD) could be helpful in KA and SCC differential diagnosis and to gain insight into the pathogenesis of KA-like neoplasms, we compared the density of CD105- and CD34-stained vessels in KAs and SCCs and their relation to the expression of the p53 oncoprotein and proliferation marker Ki67. This is an observational retrospective cohort study. Forty lesions with clinical appearance of KAs (29 KAs and 11 SCCs) entered the study. A biopsy was taken from each lesion at presentation and the natural clinical course was monitored for at least 1 month. Growing or minimally regressing lesions were submitted to complete surgical excision. The diagnoses were established on combined clinical, histological, and follow-up evaluations. The MVD and p53 or Ki67 expression in neoplastic cells were assessed through morphometry. The MVD did not show discriminating power between KAs and SCCs. The Ki67 proliferation rate was significantly higher in SCCs. Although neoangiogenesis (CD105-MVD) in KAs was associated with cell proliferation, in SCCs it was not. There was significant correlation between p53 expression and neoplasia size in SCCs but not in KAs. From our results, we may conclude that KA and SCC have similarities, as CD105- and CD34-MVD. However, the low Ki67 proliferation index and the positive correlation between Ki-67 index and neovascularization in KA suggest a dependence in neovascularization to grow in KA, pointing to involvement of distinct pathogenesis. PMID:26061320

  19. MCCE2: Improving Protein pKa Calculations with Extensive Side Chain Rotamer Sampling

    PubMed Central

    SONG, YIFAN; MAO, JUNJUN; GUNNER, M. R.

    2009-01-01

    Multiconformation continuum electrostatics (MCCE) explores different conformational degrees of freedom in Monte Carlo calculations of protein residue and ligand pKas. Explicit changes in side chain conformations throughout a titration create a position dependent, heterogeneous dielectric response giving a more accurate picture of coupled ionization and position changes. The MCCE2 methods for choosing a group of input heavy atom and proton positions are described. The pKas calculated with different isosteric conformers, heavy atom rotamers and proton positions, with different degrees of optimization are tested against a curated group of 305 experimental pKas in 33 proteins. QUICK calculations, with rotation around Asn and Gln termini, sampling His tautomers and torsion minimum hydroxyls yield an RMSD of 1.34 with 84% of the errors being <1.5 pH units. FULL calculations adding heavy atom rotamers and side chain optimization yield an RMSD of 0.90 with 90% of the errors <1.5 pH unit. Good results are also found for pKas in the membrane protein bacteriorhodopsin. The inclusion of extra side chain positions distorts the dielectric boundary and also biases the calculated pKas by creating more neutral than ionized conformers. Methods for correcting these errors are introduced. Calculations are compared with multiple X-ray and NMR derived structures in 36 soluble proteins. Calculations with X-ray structures give significantly better pKas. Results with the default protein dielectric constant of 4 are as good as those using a value of 8. PMID:19274707

  20. The biosynthesis of mycolic acids in Mycobacterium tuberculosis relies on multiple specialized elongation complexes interconnected by specific protein-protein interactions.

    PubMed

    Veyron-Churlet, Romain; Bigot, Sarah; Guerrini, Olivier; Verdoux, Sébastien; Malaga, Wladimir; Daffé, Mamadou; Zerbib, Didier

    2005-11-01

    Tuberculosis kills about two million people every year and remains one of the leading causes of mortality worldwide. As a result of the increasing antibiotic resistance of Mycobacterium tuberculosis (Mtb) strains, there is an urgent need for new antitubercular drugs. Several efficient antibiotics, including isoniazid, specifically target the fatty acid synthase-II (FAS-II) complex of mycolic acid biosynthesis. We have previously shown that there are protein-protein interactions between the components of FAS-II that are essential for mycobacterial survival. We have now looked at the potential partners of FAS-II, mtFabD, the methyltransferases MmaAs, and Pks13. A combination of yeast two-hybrid and co-immunoprecipitation experiments showed that mtFabD interacts with each beta-ketoacyl-synthase (KasA, KasB and mtFabH) and with the core of FAS-II (InhA and MabA). The methyltransferases have a greater affinity for KasA and KasB than for mtFabH, suggesting that modifications on the meromycolic chains may occur during their elongation. Finally, Pks13, which catalyzes the final Claisen condensation of mycolic acids, interacts specifically with KasB. These data allowed us to determine the architecture of the multiple specialized FAS-II complexes, giving us insights into the organization of the complete mycolic acids biosynthesis. Our studies suggest a new and crucial interaction (KasB-Pks13) as a putative target for peptidomimetic antibiotics. PMID:16213523

  1. Slow onset inhibition of bacterial beta-ketoacyl-acyl carrier protein synthases by thiolactomycin.

    PubMed

    Machutta, Carl A; Bommineni, Gopal R; Luckner, Sylvia R; Kapilashrami, Kanishk; Ruzsicska, Bela; Simmerling, Carlos; Kisker, Caroline; Tonge, Peter J

    2010-02-26

    Thiolactomycin (TLM), a natural product thiolactone antibiotic produced by species of Nocardia and Streptomyces, is an inhibitor of the beta-ketoacyl-acyl carrier protein synthase (KAS) enzymes in the bacterial fatty acid synthase pathway. Using enzyme kinetics and direct binding studies, TLM has been shown to bind preferentially to the acyl-enzyme intermediates of the KASI and KASII enzymes from Mycobacterium tuberculosis and Escherichia coli. These studies, which utilized acyl-enzyme mimics in which the active site cysteine was replaced by a glutamine, also revealed that TLM is a slow onset inhibitor of the KASI enzymes KasA and ecFabB but not of the KASII enzymes KasB and ecFabF. The differential affinity of TLM for the acyl-KAS enzymes is proposed to result from structural change involving the movement of helices alpha5 and alpha6 that prepare the enzyme to bind malonyl-AcpM or TLM and that is initiated by formation of hydrogen bonds between the acyl-enzyme thioester and the oxyanion hole. The finding that TLM is a slow onset inhibitor of ecFabB supports the proposal that the long residence time of TLM on the ecFabB homologues in Serratia marcescens and Klebsiella pneumonia is an important factor for the in vivo antibacterial activity of TLM against these two organisms despite the fact that the in vitro MIC values are only 100-200 microg/ml. The mechanistic data on the interaction of TLM with KasA will provide an important foundation for the rational development of high affinity KasA inhibitors based on the thiolactone skeleton. PMID:20018879

  2. Thiolactomycin-Based Inhibitors of Bacterial β-Ketoacyl-ACP Synthases with in Vivo Activity.

    PubMed

    Bommineni, Gopal R; Kapilashrami, Kanishk; Cummings, Jason E; Lu, Yang; Knudson, Susan E; Gu, Chendi; Walker, Stephen G; Slayden, Richard A; Tonge, Peter J

    2016-06-01

    β-Ketoacyl-ACP synthases (KAS) are key enzymes involved in the type II bacterial fatty acid biosynthesis (FASII) pathway and are putative targets for antibacterial discovery. Several natural product KAS inhibitors have previously been reported, including thiolactomycin (TLM), which is produced by Nocardia spp. Here we describe the synthesis and characterization of optically pure 5R-thiolactomycin (TLM) analogues that show improved whole cell activity against bacterial strains including methicillin-resistant Staphylococcus aureus (MRSA) and priority pathogens such as Francisella tularensis and Burkholderia pseudomallei. In addition, we identify TLM analogues with in vivo efficacy against MRSA and Klebsiella pneumoniae in animal models of infection. PMID:27187871

  3. The autoxidation and proton dissociation constants of tertiary diphosphines: relevance to biological activity.

    PubMed

    Berners-Price, S J; Norman, R E; Sadler, P J

    1987-11-01

    The pKas and autoxidation properties of a number of diphosphines which exhibit varying degrees of antitumor and cytotoxic activity were investigated. Titration by HClO4 in CH3NO2 was used to determine pKas of the following diphosphines: R2P(CH2)nPR'2, where for R = R' = Ph, n = 1, 2, and 3 (dppm, dppe, and dppp respectively); for R = R' = Et, n = 2 (depe); for R = Ph, R' = Et, n = 2 (eppe); and for cis and trans Ph2PCH = CHPPh2 (dppey). The difference between the first and second protonation constants decreases as the length of the carbon chain between the two phosphorus centers increases. Unsaturation in the carbon chain lowers pKas. -PEt2 centers are apparently more basic than -PPh2 centers. Apart from electrostatic effects, the protonation of a given phosphine center appears to be independent of the substituents at the second phosphine center. The autoxidation reactions of dppm, dppe, dppp, depe, and cis-dppey were studied in a variety of solvents by 31P NMR spectroscopy. The ethyl-substituted diphosphines were much more rapidly oxidized than the phenyl-substituted, and the pathways of autoxidation differed. Generally, the phenyl-substituted diphosphines gave only mono- and dioxides, while the ethyl-substituted diphosphines additionally gave phosphinites and other oxidation products. The relevance of the autoxidation reactivity and the pKas to the contrasting antitumor activity of these diphosphines is discussed. PMID:2828542

  4. Knowledge and abilities catalog for nuclear power plant operators: Boiling water reactors, Revision 1

    SciTech Connect

    1995-08-01

    The Knowledge and Abilities Catalog for Nuclear Power Plant Operators: Boiling-Water Reactors (BWRs) (NUREG-1123, Revision 1) provides the basis for the development of content-valid licensing examinations for reactor operators (ROs) and senior reactor operators (SROs). The examinations developed using the BWR Catalog along with the Operator Licensing Examiner Standards (NUREG-1021) and the Examiner`s Handbook for Developing Operator Licensing Written Examinations (NUREG/BR-0122), will cover the topics listed under Title 10, Code of Federal Regulations, Part 55 (10 CFR 55). The BWR Catalog contains approximately 7,000 knowledge and ability (K/A) statements for ROs and SROs at BWRs. The catalog is organized into six major sections: Organization of the Catalog, Generic Knowledge and Ability Statements, Plant Systems grouped by Safety Functions, Emergency and Abnormal Plant Evolutions, Components, and Theory. Revision 1 to the BWR Catalog represents a modification in form and content of the original catalog. The K/As were linked to their applicable 10 CFR 55 item numbers. SRO level K/As were identified by 10 CFR 55.43 item numbers. The plant-wide generic and system generic K/As were combined in one section with approximately one hundred new K/As. Component Cooling Water and Instrument Air Systems were added to the Systems Section. Finally, High Containment Hydrogen Concentration and Plant Fire On Site evolutions added to the Emergency and Abnormal Plant Evolutions section.

  5. Colorado State University Program for developing, testing, evaluating and optimizing solar heating and cooling systems. Project status report, August--September 1994

    SciTech Connect

    Hittle, D.C.

    1994-11-01

    The current work has been to validate Florida Solar Energy Center`s models of the Solahart 302K and 302K-AS systems to prepare a rating for the Sacramento Municipal Utility District`s rebate program for solar domestic hot water heaters.

  6. Calculations of fluid-mineral equilibria in the Aspo Hard Rock Laboratory

    SciTech Connect

    Bruton, C.J.

    1995-05-01

    The purpose of this report is to evaluate the utility of the EQ3/6 geochemical codes in describing mineral-fluid equilibria in the low temperature (<25{degrees}C) systems at the Aespoe Hard Rock Laboratory (HRL). Data on fluid chemistry and on fracture-filling mineralogy with depth were obtained from Smellie and Laaksoharju. Average temperatures in the HRL boreholes are generally less than 20{degrees}C. EQ3/6 was used to evaluate the extent to which equilibrium is achieved between minerals and fluids in these systems. Smellie and Laaksoharju used the PHREEQE geochemical modeling code to calculate saturation indices for fracture-lining minerals in boreholes KAS02, KAS03, KAS04 and KAS06 in order to ``support the presence or absence of the major fracture minerals``. They noted that only calcite and gypsum may be expected to attain equilibrium under the low temperature conditions Aespoe. However, they used closeness to equilibrium as an indicator of ``stable conditions, long bedrock residence/reaction times and slow to stagnant flow in the system.`` EQ3 was used to calculate mineral saturation indices for comparison, and EQ6 was used to try to predict the mineral assemblages coexisting with fluids.

  7. 10 CFR 26.4 - FFD program applicability to categories of individuals.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... other entities may rely on a local hospital or other organization that meets the requirements of 49 CFR... Services (HHS); (4) Training is provided to address the knowledge and abilities (KAs) listed in § 26.29(a... Provisions § 26.4 FFD program applicability to categories of individuals. (a) All persons who are...

  8. 10 CFR 26.29 - Training.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... KAs in paragraph (a) of this section. The examination must include a comprehensive random sampling of... COMMISSION FITNESS FOR DUTY PROGRAMS Program Elements § 26.29 Training. (a) Training content. Licensees and other entities shall ensure that the individuals who are subject to this subpart have the following...

  9. 10 CFR 26.29 - Training.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... KAs in paragraph (a) of this section. The examination must include a comprehensive random sampling of... COMMISSION FITNESS FOR DUTY PROGRAMS Program Elements § 26.29 Training. (a) Training content. Licensees and other entities shall ensure that the individuals who are subject to this subpart have the following...

  10. 10 CFR 26.4 - FFD program applicability to categories of individuals.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... other entities may rely on a local hospital or other organization that meets the requirements of 49 CFR... Services (HHS); (4) Training is provided to address the knowledge and abilities (KAs) listed in § 26.29(a... Provisions § 26.4 FFD program applicability to categories of individuals. (a) All persons who are...

  11. 10 CFR 26.29 - Training.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... KAs in paragraph (a) of this section. The examination must include a comprehensive random sampling of... COMMISSION FITNESS FOR DUTY PROGRAMS Program Elements § 26.29 Training. (a) Training content. Licensees and other entities shall ensure that the individuals who are subject to this subpart have the following...

  12. 10 CFR 26.203 - General provisions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... shall add the following KAs to the content of the training that is required in § 26.29(a) and the... REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Managing Fatigue § 26.203 General provisions. (a) Policy. Licensees shall establish a policy for the management of fatigue for all individuals who are subject to...

  13. 10 CFR 26.29 - Training.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... KAs in paragraph (a) of this section. The examination must include a comprehensive random sampling of... COMMISSION FITNESS FOR DUTY PROGRAMS Program Elements § 26.29 Training. (a) Training content. Licensees and other entities shall ensure that the individuals who are subject to this subpart have the following...

  14. 78 FR 19308 - Notice of Intent To Repatriate Cultural Items: University of Denver Museum of Anthropology...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-29

    ... a cultural affiliation with the cultural items should contact the University of Denver Museum of... civilizations. He housed his artifact collection in his Ko-Kas-Ki Museum in Pinedale, CO, before transferring it... figurine fragments (DU 3915 A-B) were removed from unknown sites near Gila Crossing Ruin in Maricopa...

  15. 10 CFR 26.203 - General provisions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... shall add the following KAs to the content of the training that is required in § 26.29(a) and the... REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Managing Fatigue § 26.203 General provisions. (a) Policy. Licensees shall establish a policy for the management of fatigue for all individuals who are subject to...

  16. 10 CFR 26.203 - General provisions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... shall add the following KAs to the content of the training that is required in § 26.29(a) and the... REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Managing Fatigue § 26.203 General provisions. (a) Policy. Licensees shall establish a policy for the management of fatigue for all individuals who are subject to...

  17. 10 CFR 26.4 - FFD program applicability to categories of individuals.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... other entities may rely on a local hospital or other organization that meets the requirements of 49 CFR... Services (HHS); (4) Training is provided to address the knowledge and abilities (KAs) listed in § 26.29(a... Provisions § 26.4 FFD program applicability to categories of individuals. (a) All persons who are...

  18. 10 CFR 26.4 - FFD program applicability to categories of individuals.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... other entities may rely on a local hospital or other organization that meets the requirements of 49 CFR... Services (HHS); (4) Training is provided to address the knowledge and abilities (KAs) listed in § 26.29(a... Provisions § 26.4 FFD program applicability to categories of individuals. (a) All persons who are...

  19. 10 CFR 26.29 - Training.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... KAs in paragraph (a) of this section. The examination must include a comprehensive random sampling of... COMMISSION FITNESS FOR DUTY PROGRAMS Program Elements § 26.29 Training. (a) Training content. Licensees and other entities shall ensure that the individuals who are subject to this subpart have the following...

  20. 10 CFR 26.4 - FFD program applicability to categories of individuals.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... other entities may rely on a local hospital or other organization that meets the requirements of 49 CFR... Services (HHS); (4) Training is provided to address the knowledge and abilities (KAs) listed in § 26.29(a... Provisions § 26.4 FFD program applicability to categories of individuals. (a) All persons who are...

  1. 10 CFR 26.203 - General provisions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... shall add the following KAs to the content of the training that is required in § 26.29(a) and the... REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Managing Fatigue § 26.203 General provisions. (a) Policy. Licensees shall establish a policy for the management of fatigue for all individuals who are subject to...

  2. 10 CFR 26.203 - General provisions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... shall add the following KAs to the content of the training that is required in § 26.29(a) and the... REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Managing Fatigue § 26.203 General provisions. (a) Policy. Licensees shall establish a policy for the management of fatigue for all individuals who are subject to...

  3. A novel interaction linking the FAS-II and phthiocerol dimycocerosate (PDIM) biosynthetic pathways.

    PubMed

    Kruh, Nicole A; Borgaro, Janine G; Ruzsicska, Béla P; Xu, Hua; Tonge, Peter J

    2008-11-14

    The fatty acid biosynthesis (FAS-II) pathway in Mycobacterium tuberculosis generates long chain fatty acids that serve as the precursors to mycolic acids, essential components of the mycobacterial cell wall. Enzymes in the FAS-II pathway are thought to form one or more noncovalent multi-enzyme complexes within the cell, and a bacterial two-hybrid screen was used to search for missing components of the pathway and to furnish additional data on interactions involving these enzymes in vivo. Using the FAS-II beta-ketoacyl synthase, KasA, as bait, an extensive bacterial two-hybrid screen of a M. tuberculosis genome fragment library unexpectedly revealed a novel interaction between KasA and PpsB as well as PpsD, two polyketide modules involved in the biosynthesis of the virulence lipid phthiocerol dimycocerosate (PDIM). Sequence analysis revealed that KasA interacts with PpsB and PpsD in the region of the acyl carrier domain of each protein, raising the possibility that lipids could be transferred between the FAS-II and PDIM biosynthetic pathways. Subsequent studies utilizing purified proteins and radiolabeled lipids revealed that fatty acids loaded onto PpsB were transferred to KasA and also incorporated into long chain fatty acids synthesized using a Mycobacterium smegmatis lysate. These data suggest that in addition to producing PDIMs, the growing phthiocerol product can also be shuttled into the FAS-II pathway via KasA as an entry point for further elongation. Interactions between these biosynthetic pathways may exist as a simple means to increase mycobacterial lipid diversity, enhancing functionality and the overall complexity of the cell wall. PMID:18703500

  4. Substrate Recognition by β-Ketoacyl-ACP Synthases†

    PubMed Central

    Borgaro, Janine G.; Chang, Andrew; Machutta, Carl A.; Zhang, Xujie; Tonge, Peter J.

    2011-01-01

    β-Ketoacyl-ACP synthase (KAS) enzymes catalyze Claisen condensation reactions in the fatty acid biosynthesis pathway. These reactions follow a ping-pong mechanism in which a donor substrate acylates the active site cysteine residue after which the acyl group is condensed with the malonyl-ACP acceptor substrate to form a β-ketoacyl-ACP. In the priming KASIII enzymes the donor substrate is an acyl-CoA while in the elongating KASI and KASII enzymes the donor is an acyl-ACP. Although the KASIII enzyme in Escherichia coli (ecFabH) is essential, the corresponding enzyme in Mycobacterium tuberculosis (mtFabH) is not, suggesting that the KASI or II enzyme in M. tuberculosis (KasA or KasB, respectively) must be able to accept a CoA donor substrate. Since KasA is essential, the substrate specificity of this KASI enzyme has been explored using substrates based on phosphopantetheine, CoA, ACP and AcpM peptide mimics. This analysis has been extended to the KASI and KASII enzymes from E. coli (ecFabB and ecFabF) where we show that a 14 residue malonyl-phosphopantetheine peptide can efficiently replace malonyl-ecACP as the acceptor substrate in the ecFabF reaction. While ecFabF is able to catalyze the condensation reaction when CoA is the carrier for both substrates, the KASI enzymes ecFabB and KasA have an absolute requirement for an ACP substrate as the acyl donor. Provided that this requirement is met, variation in the acceptor carrier substrate has little impact on the kcat/Km for the KASI reaction. For the KASI enzymes we propose that the binding of ecACP (AcpM) results in a conformational change that leads to an open form of the enzyme to which the malonyl acceptor substrate binds. Finally, the substrate inhibition observed when palmitoyl-CoA is the donor substrate for the KasA reaction has implications for the importance of mtFabH in the mycobacterial FASII pathway. PMID:22017312

  5. Substrate recognition by β-ketoacyl-ACP synthases.

    PubMed

    Borgaro, Janine G; Chang, Andrew; Machutta, Carl A; Zhang, Xujie; Tonge, Peter J

    2011-12-13

    β-Ketoacyl-ACP synthase (KAS) enzymes catalyze Claisen condensation reactions in the fatty acid biosynthesis pathway. These reactions follow a ping-pong mechanism in which a donor substrate acylates the active site cysteine residue after which the acyl group is condensed with the malonyl-ACP acceptor substrate to form a β-ketoacyl-ACP. In the priming KASIII enzymes the donor substrate is an acyl-CoA while in the elongating KASI and KASII enzymes the donor is an acyl-ACP. Although the KASIII enzyme in Escherichia coli (ecFabH) is essential, the corresponding enzyme in Mycobacterium tuberculosis (mtFabH) is not, suggesting that the KASI or II enzyme in M. tuberculosis (KasA or KasB, respectively) must be able to accept a CoA donor substrate. Since KasA is essential, the substrate specificity of this KASI enzyme has been explored using substrates based on phosphopantetheine, CoA, ACP, and AcpM peptide mimics. This analysis has been extended to the KASI and KASII enzymes from E. coli (ecFabB and ecFabF) where we show that a 14-residue malonyl-phosphopantetheine peptide can efficiently replace malonyl-ecACP as the acceptor substrate in the ecFabF reaction. While ecFabF is able to catalyze the condensation reaction when CoA is the carrier for both substrates, the KASI enzymes ecFabB and KasA have an absolute requirement for an ACP substrate as the acyl donor. Provided that this requirement is met, variation in the acceptor carrier substrate has little impact on the k(cat)/K(m) for the KASI reaction. For the KASI enzymes we propose that the binding of ecACP (AcpM) results in a conformational change that leads to an open form of the enzyme to which the malonyl acceptor substrate binds. Finally, the substrate inhibition observed when palmitoyl-CoA is the donor substrate for the KasA reaction has implications for the importance of mtFabH in the mycobacterial FASII pathway. PMID:22017312

  6. Constitutive modulation of Raf-1 protein kinase is associated with differential gene expression of several known and unknown genes.

    PubMed Central

    Patel, S.; Wang, F. H.; Whiteside, T. L.; Kasid, U.

    1997-01-01

    BACKGROUND: Raf-1, a cytoplasmic serine/threonine protein kinase, plays an important role in mitogen- and damage-responsive cellular signal transduction pathways. Consistent with this notion is the fact that constitutive modulation of expression and/or activity of Raf-1 protein kinase modifies cell growth, proliferation, and cell survival. Although these effects are controlled at least in part by transcriptional mechanisms, the role of Raf-1 in the regulation of specific gene expression is unclear. MATERIALS AND METHODS: Differential display of mRNA was used to identify the genes differentially expressed in human head and neck squamous carcinoma cells (PCI-06A) transfected with either the antisense c-raf-1 cDNA (PCI-06A-Raf(AS)), or a portion of cDNA coding for the kinase domain of Raf-1 (PCI-06A-Raf(K)). The differentially expressed fragments were cloned and sequenced, and they were used as probes to compare the expression patterns in parent transfectants by Northern blot analysis. In addition, expression patterns of the novel genes were examined in normal tissues and cancer cell lines. RESULTS: Six differentially expressed cDNA fragments were identified and sequenced. Northern blot analysis revealed that four of these fragments representing human alpha 1-antichymotrypsin (alpha 1-ACT), mitochondrial cytochrome c oxidase subunit II (COX-II), and two as-yet unidentified cDNAs (KAS-110 and KAS-111) were relatively overexpressed in PCI-06A-Raf(AS) transfectants compared with PCI-06A-Raf(K) transfectants. The other two cDNA fragments representing human elongation factor-1 alpha (HEF-1 alpha) and ornithine decarboxylase antizyme (OAz) were overexpressed in PCI-06A-Raf(K) transfectants compared with PCI-06A-Raf(AS) transfectants. The KAS-110 (114 bp) and KAS-111 (202 bp) cDNAs did not show significant matches with sequences in the GenEMBL, TIGR, and HGS DNA databases, and these may represent novel genes. The KAS-110 and KAS-111 transcripts, approximately 0.9 kb and

  7. Nonisothermal Thermogravimetric Analysis of Thai Lignite with High CaO Content

    PubMed Central

    Pintana, Pakamon

    2013-01-01

    Thermal behaviors and combustion kinetics of Thai lignite with different SO3-free CaO contents were investigated. Nonisothermal thermogravimetric method was carried out under oxygen environment at heating rates of 10, 30, and 50°C min−1 from ambient up to 1300°C. Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods were adopted to estimate the apparent activation energy (E) for the thermal decomposition of these coals. Different thermal degradation behaviors were observed in lignites with low (14%) and high (42%) CaO content. Activation energy of the lignite combustion was found to vary with the conversion fraction. In comparison with the KAS method, higher E values were obtained by the FWO method for all conversions considered. High CaO lignite was observed to have higher activation energy than the low CaO coal. PMID:24250259

  8. Regulation of lipid biosynthesis, sliding motility, and biofilm formation by a membrane-anchored nucleoid-associated protein of Mycobacterium tuberculosis.

    PubMed

    Ghosh, Soumitra; Indi, Shantinath S; Nagaraja, Valakunja

    2013-04-01

    Bacteria use a number of small basic proteins for organization and compaction of their genomes. By their interaction with DNA, these nucleoid-associated proteins (NAPs) also influence gene expression. Rv3852, a NAP of Mycobacterium tuberculosis, is conserved among the pathogenic and slow-growing species of mycobacteria. Here, we show that the protein predominantly localizes in the cell membrane and that the carboxy-terminal region with the propensity to form a transmembrane helix is necessary for its membrane localization. The protein is involved in genome organization, and its ectopic expression in Mycobacterium smegmatis resulted in altered nucleoid morphology, defects in biofilm formation, sliding motility, and change in apolar lipid profile. We demonstrate its crucial role in regulating the expression of KasA, KasB, and GroEL1 proteins, which are in turn involved in controlling the surface phenotypes in mycobacteria. PMID:23396914

  9. Rv3080c regulates the rate of inhibition of mycobacteria by isoniazid through FabD.

    PubMed

    Kumari, Ruma; Saxena, Richa; Tiwari, Sameer; Tripathi, Dinesh K; Srivastava, Kishore K

    2013-02-01

    The mycobacterial FASII multi-enzyme complex has been identified to be a target of Ser/Thr protein kinases (STPKs) of Mycobacterium tuberculosis (MTB), with substrates, including the malonyl-CoA:ACP transacylase (FabD) and the β-ketoacyl-ACP synthases KasA and KasB. These proteins are phosphorylated by various kinases in vitro. The present study links the correlation of FASII pathway with serine threonine protein kinase of MTB. In the preliminary finding, we have shown that mycobacterial protein Rv3080c (PknK) phosphorylates FabD and the knockdown of PknK protein in mycobacteria down regulates FabD expression. This event leads to the differential inhibition of mycobacteria in the presence of isoniazid (INH), as the inhibition of growth of mycobacteria in the presence of INH is enhanced in PknK deficient mycobacteria. PMID:23180244

  10. 2-Aminothiazole derivatives as antimycobacterial agents: Synthesis, characterization, in vitro and in silico studies.

    PubMed

    Makam, Parameshwar; Kannan, Tharanikkarasu

    2014-11-24

    A series of 2-aminothiazole derivatives with a wide range of substitutions at 2-, 4- and 5-positions were designed and synthesized using Hantzsch thiazole synthesis. These compounds were evaluated for their inhibitory potential against Mycobacterium tuberculosis (Mtb), H37Rv. The compound, 7n showed high antimycobacterial activity with MIC value of 6.25 μM and the succeeding compounds, 7b, 7e and 7f also exhibited antimycobacterial activity with MIC value of 12.50 μM. Docking studies of these molecules with β-Ketoacyl-ACP Synthase (KasA) protein of Mtb have been carried out to understand the mechanism of antimycobacterial action. The compound, 7n showed good interaction with KasA protein with the Ki value of 0.44 μM. PMID:25305331

  11. Physiological function of mycobacterial mtFabD, an essential malonyl-CoA:AcpM transacylase of type 2 fatty acid synthase FASII, in yeast mct1Delta cells.

    PubMed

    Gurvitz, Aner

    2009-01-01

    Mycobacterium tuberculosis mtFabD is an essential malonyl-CoA:AcpM transacylase and is important for vital protein-protein interactions within type 2 fatty acid synthase FASII. mtFabD contacts KasA, KasB, FabH, InhA, and possibly also HadAB, HadBC, and FabG1/MabA. Disruption of mtFabD's interactions during FASII has been proposed for drug development. Here, the gene for a mitochondrially targeted mtFabD was ectopically expressed in Saccharomyces cerevisiae mct1Delta mutant cells lacking the corresponding mitochondrial malonyl-CoA transferase Mct1p, allowing the mutants to recover their abilities to respire on glycerol and synthesize lipoic acid. Hence, mtFabD could physiologically function in an environment lacking holo-AcpM or other native interaction partners. PMID:19859569

  12. Inhibition of a Mycobacterium tuberculosis beta-ketoacyl ACP synthase by isoniazid.

    PubMed

    Mdluli, K; Slayden, R A; Zhu, Y; Ramaswamy, S; Pan, X; Mead, D; Crane, D D; Musser, J M; Barry, C E

    1998-06-01

    Although isoniazid (isonicotinic acid hydrazide, INH) is widely used for the treatment of tuberculosis, its molecular target has remained elusive. In response to INH treatment, saturated hexacosanoic acid (C26:0) accumulated on a 12-kilodalton acyl carrier protein (AcpM) that normally carried mycolic acid precursors as long as C50. A protein species purified from INH-treated Mycobacterium tuberculosis was shown to consist of a covalent complex of INH, AcpM, and a beta-ketoacyl acyl carrier protein synthase, KasA. Amino acid-altering mutations in the KasA protein were identified in INH-resistant patient isolates that lacked other mutations associated with resistance to this drug. PMID:9616124

  13. Regulation of Lipid Biosynthesis, Sliding Motility, and Biofilm Formation by a Membrane-Anchored Nucleoid-Associated Protein of Mycobacterium tuberculosis

    PubMed Central

    Ghosh, Soumitra; Indi, Shantinath S.

    2013-01-01

    Bacteria use a number of small basic proteins for organization and compaction of their genomes. By their interaction with DNA, these nucleoid-associated proteins (NAPs) also influence gene expression. Rv3852, a NAP of Mycobacterium tuberculosis, is conserved among the pathogenic and slow-growing species of mycobacteria. Here, we show that the protein predominantly localizes in the cell membrane and that the carboxy-terminal region with the propensity to form a transmembrane helix is necessary for its membrane localization. The protein is involved in genome organization, and its ectopic expression in Mycobacterium smegmatis resulted in altered nucleoid morphology, defects in biofilm formation, sliding motility, and change in apolar lipid profile. We demonstrate its crucial role in regulating the expression of KasA, KasB, and GroEL1 proteins, which are in turn involved in controlling the surface phenotypes in mycobacteria. PMID:23396914

  14. HIV-positive woman's appeal for absolute discharge dismissed on grounds of public safety.

    PubMed

    2008-07-01

    On 7 December 2007, the Nova Scotia Court of Appeal dismissed an appeal from a June 2007 order of the Nova Scotia Review Board providing that an HIV-positive woman, "K.A.S.," be discharged with conditions to reside in hospital-approved premises, to continue with recommended mental health treatment, and to abstain from alcohol and illicit drug use because she continued to present a significant risk to the safety of the public. PMID:18727198

  15. Korean American women's perceptions about physical examinations and cancer screening services offered in Korea: the influences of medical tourism on Korean Americans.

    PubMed

    Oh, Kyeung Mi; Jun, Jungmi; Zhou, Qiuping; Kreps, Gary

    2014-04-01

    Cancer is the leading cause of death for Korean-Americans (KAs), while cancer screening rates among KAs have been consistently low. Seven semi-structured focus group interviews with 34 KA women aged 40 or older in the Washington, DC metropolitan area were conducted to explore the perceptions of KA women about seeking physical examinations and cancer screening services in Korea. Data were analyzed using a framework approach. Informants positively perceived the use of health screening services in Korea in comparison to seeking such services in the US. Decision-making factors included cost benefits, high quality services, and more convenient screening procedures in Korea. These benefits outweighed the risks of delaying health care and travelling a vast distance with incurring additional travel costs. Motivations to seek these services in Korea included opportunities to visit their homeland and to enjoy comfortable communication with their native language. The increase of available information about Korean medical services due to the industry's aggressive marketing/PR was identified as a facilitator. Most informants did not recognize possible negative health outcomes of obtaining services in Korea such as inappropriate follow up care if having abnormal findings. Educational programs are needed to educate KAs about the benefits and risks of getting the services in Korea and proper follow up care in the US. Health care providers need to know the different cancer risks and screening needs for this population. PMID:24322599

  16. CD1A-positive cells and HSP60 (HSPD1) levels in keratoacanthoma and squamous cell carcinoma.

    PubMed

    Cabibi, Daniela; Conway de Macario, Everly; Ingrao, Sabrina; Porcasi, Rossana; Zucco, Francesco; Macario, Alberto J L; Cappello, Francesco; Rappa, Francesca

    2016-01-01

    CD1a is involved in presentation to the immune system of lipid antigen derived from tumor cells with subsequent T cell activation. Hsp60 is a molecular chaperone implicated in carcinogenesis by, for instance, modulating the immune reaction against the tumor. We have previously postulated a synergism between CD1a and Hsp60 as a key factor in the activation of an effective antitumor immune response in squamous epithelia. Keratoacantomas (KAs) are benign tumors that however can transform into squamous cell carcinomas (SCCs), but the reasons for this malignization are unknown. In a previous study, we found that CD1a-positive cells are significantly more numerous in KA than in SCC. In this study, we analyzed a series of KAs and SCCs by immunohistochemistry for CD1a and Hsp60. Our results show that the levels of both are significantly lower in KA than in SCC and support the hypothesis that KA may evolve towards SCC if there is a failure of the local modulation of the antitumor immune response. The data also show that immunohistochemistry for CD1a and Hsp60 can be of help in differential diagnosis between KAs and well-differentiated forms of SCC. PMID:26442925

  17. Korean-Americans' Knowledge about Depression and Attitudes about Treatment Options.

    PubMed

    Kim, Eunjung; Im, Eun-Ok

    2015-06-01

    The purpose of this pilot study was to explore first-generation Korean-Americans' knowledge about depression and attitudes about depression treatment options. Self-report survey data were gathered from 73 first-generation Korean-Americans (KAs) using instruments developed for this study. The data were analyzed using descriptive and inferential statistics including t-tests. Data indicated participants lacked knowledge about depression. Among all depression treatment options, exercise was the option that first-generation KAs were most willing to try and was rated as having the least shame attached to it. Taking an antidepressant was the option KAs reported being most unwilling to try and had the highest shame attached to it. No significant differences in knowledge about depression and attitudes about depression treatment options were found between low and high acculturation groups, with the exception that the high acculturation group demonstrated more agreement than the low acculturation group with the item that emotional symptoms, such as mood changes, can be depression symptoms. These results suggest that initiating depression treatment with exercise may be the most acceptable starting point in treating depression in first-generation KA immigrants. PMID:26241572

  18. Characterization of Sea Lettuce Surface Functional Groups by Potentiometric Titrations

    NASA Astrophysics Data System (ADS)

    Ebling, A. M.; Schijf, J.

    2008-12-01

    In pursuit of our ultimate goal to better understand the prodigious capacity of the marine macroalga Ulva lactuca (sea lettuce) for adsorbing a broad range of dissolved trace metals from seawater, we performed an initial characterization of its surface functional groups. Specifically, the number of distinct functional groups as well as their individual bulk concentrations and acid dissociation constants (pKas) were determined by potentiometric titrations in NaCl solutions of various ionic strengths (I = 0.01-5.0 M), under inert nitrogen atmosphere at 25°C. Depending on the ionic strength, Ulva samples were manually titrated down to pH 2 or 3 with 1 N HCl and then up to pH 10 with 1 N NaOH in steps of 0.1-0.2 units, continuously monitoring pH with a glass combination electrode. Titrations of a dehydrated Ulva standard reference material (BCR-279) were compared with fresh Ulva tissue cultured in our laboratory. A titration in filtered natural seawater was also compared with one in an NaCl solution of equal ionic strength. Equilibrium constants for the ionization of water in NaCl solutions as a function of ionic strength were obtained from the literature. Fits to the titration data ([H]T vs. pH) were performed with the FITEQL4.0 computer code using non-electrostatic 3-, 4-, and 5-site models, either by fixing ionic strength at its experimental value or by allowing it to be extrapolated to zero, while considering all functional group pKas and bulk concentrations as adjustable parameters. Since pKas and bulk concentrations were found to be strongly correlated, the latter were also fixed in some cases to further constrain the pKas. Whereas these calculations are currently ongoing, preliminary results point to three, possibly four, functional groups with pKas of about 4.1, 6.3, and 9.5 at I = 0. Bulk concentrations of the three groups are very similar, about 5-6×10-4 mol/g based on dry weight, which suggests that all are homogeneously distributed over the surface and

  19. Improved pKa calculations through flexibility based sampling of a water-dominated interaction scheme

    PubMed Central

    Warwicker, Jim

    2004-01-01

    Ionizable groups play critical roles in biological processes. Computation of pKas is complicated by model approximations and multiple conformations. Calculated and experimental pKas are compared for relatively inflexible active-site side chains, to develop an empirical model for hydration entropy changes upon charge burial. The modification is found to be generally small, but large for cysteine, consistent with small molecule ionization data and with partial charge distributions in ionized and neutral forms. The hydration model predicts significant entropic contributions for ionizable residue burial, demonstrated for components in the pyruvate dehydrogenase complex. Conformational relaxation in a pH-titration is estimated with a mean-field assessment of maximal side chain solvent accessibility. All ionizable residues interact within a low protein dielectric finite difference (FD) scheme, and more flexible groups also access water-mediated Debye-Hückel (DH) interactions. The DH method tends to match overall pH-dependent stability, while FD can be more accurate for active-site groups. Tolerance for side chain rotamer packing is varied, defining access to DH interactions, and the best fit with experimental pKas obtained. The new (FD/DH) method provides a fast computational framework for making the distinction between buried and solvent-accessible groups that has been qualitatively apparent from previous work, and pKa calculations are significantly improved for a mixed set of ionizable residues. Its effectiveness is also demonstrated with computation of the pH-dependence of electrostatic energy, recovering favorable contributions to folded state stability and, in relation to structural genomics, with substantial improvement (reduction of false positives) in active-site identification by electrostatic strain. PMID:15388865

  20. Decarboxylation of malonyl-(acyl carrier protein) by 3-oxoacyl-(acyl carrier protein) synthases in plant fatty acid biosynthesis.

    PubMed Central

    Winter, E; Brummel, M; Schuch, R; Spener, F

    1997-01-01

    In order to identify regulatory steps in fatty acid biosynthesis, the influence of intermediate 3-oxoacyl-(acyl carrier proteins) (3-oxoacyl-ACPs) and end-product acyl-ACPs of the fatty acid synthase reaction on the condensation reaction was investigated in vitro, using total fatty acid synthase preparations and purified 3-oxoacyl-ACP synthases (KASs; EC 2.3.1.41) from Cuphea lanceolata seeds. KAS I and II in the fatty acid synthase preparations were assayed for the elongation of octanoyl- and hexadecanoyl-ACP respectively, and the accumulation of the corresponding condensation product 3-oxoacyl-ACP was studied by modulating the content of the reducing equivalentS NADH and NADPH. Complete omission of reducing equivalents resulted with either KAS in the abnormal synthesis of acetyl-ACP from malonyl-ACP by a decarboxylation reaction. Supplementation with NADPH or NADH, separately or in combination with recombinant 3-oxoacyl-ACP reductase (EC 1.1.1.100), led to a decrease in the amount of acetyl-ACP and a simultaneous increase in elongation products. This demonstrates that the accumulation of 3-oxoacyl-ACP inhibits the condensation reaction on the one hand, and induces the decarboxylation of malonyl-ACP on the other. By carrying out similar experiments with purified enzymes, this decarboxylation was attributed to the action of KAS. Our data point to a regulatory mechanism for the degradation of malonyl-ACP in plants which is activated by the accumulation of the fatty acid synthase intermediate 3-oxoacyl-ACP. PMID:9020860

  1. Psychometrics of shared decision making and communication as patient centered measures for two language groups.

    PubMed

    Alvarez, Kiara; Wang, Ye; Alegria, Margarita; Ault-Brutus, Andrea; Ramanayake, Natasha; Yeh, Yi-Hui; Jeffries, Julia R; Shrout, Patrick E

    2016-09-01

    Shared decision making (SDM) and effective patient-provider communication are key and interrelated elements of patient-centered care that impact health and behavioral health outcomes. Measurement of SDM and communication from the patient's perspective is necessary in order to ensure that health care systems and individual providers are responsive to patient views. However, there is a void of research addressing the psychometric properties of these measures with diverse patients, including non-English speakers, and in the context of behavioral health encounters. This study evaluated the psychometric properties of 2 patient-centered outcome measures, the Shared Decision-Making Questionnaire-9 (SDM-Q) and the Kim Alliance Scale-Communication subscale (KAS-CM), in a sample of 239 English and Spanish-speaking behavioral health patients. One dominant factor was found for each scale and this structure was used to examine whether there was measurement invariance across the 2 language groups. One SDM-Q item was inconsistent with the configural invariance comparison and was removed. The remaining SDM-Q items exhibited strong invariance, meaning that item loadings and item means were similar across the 2 groups. The KAS-CM items had limited variability, with most respondents indicating high communication levels, and the invariance analysis was done on binary versions of the items. These had metric invariance (loadings the same over groups) but several items violated the strong invariance test. In both groups, the SDM-Q had high internal consistency, whereas the KAS-CM was only adequate. These findings help interpret results for individual patients, taking into account cultural and linguistic differences in how patients perceive SDM and patient-provider communication. (PsycINFO Database Record PMID:27537002

  2. HBV-Related Health Behaviors in a Socio-Cultural Context: Perspectives from Khmers and Koreans

    PubMed Central

    Lee, Haeok; Kiang, Peter; Chea, Phala; Peou, Sonith; Tang, Shirley S.; Yang, JinHwang; Fawcett, Jacqueline; Hann, Hie-Won

    2014-01-01

    Purpose To explore factors influencing health and health care within the sociocultural context of Cambodian Americans (CAs or Khmers) and Korean Americans (KA) and to examine intergroup similarities and differences between CAs and KAs, focusing on hepatitis B virus (HBV) and liver cancer prevention behaviors. Methods The study used a qualitative design guided by the revised Network Episode Model (NEM) and informed by ethnographic analysis. Focus group interviews with key informants among CA community health leaders (CHLs, n=14) and individual interviews with key informants of KA CHLs (n=9) were audiotaped and transcribed. Results Three categories that influenced HBV and liver cancer prevention emerged from both CAs and KAs: the socio-cultural, individual, and behavioral. Four additional sub-categories (sub-themes) of sociocultural were identified as socio-history, socio-medicine, socio-linguistic, and socio-health resources. Both CAs and KAs, however, have low levels of knowledge and significant misunderstandings about HBV infection. Conclusions The study identifies and compares the social-cultural determinant for HBV and liver cancer and highlights the factors of education, intercultural communication, and interactions within socio-cultural contexts of CA and KA subgroups. In general, conceptual overlaps are apparent between Khmers (from now on, the terms, CA and Khmer, will be used interchangeably) and Koreans except for the sub-theme of socio-history. However, differences in concept-specific attributes point to the need to account for differing conceptualizations and implications of specific ethnic groups’ sociocultural contexts, and to design contextually-relevant outreach and educational interventions for targeted AAPI subgroups. PMID:24355416

  3. Analysis of a plant complex resistance gene locus underlying immune-related hybrid incompatibility and its occurrence in nature.

    PubMed

    Alcázar, Rubén; von Reth, Marcel; Bautor, Jaqueline; Chae, Eunyoung; Weigel, Detlef; Koornneef, Maarten; Parker, Jane E

    2014-12-01

    Mechanisms underlying speciation in plants include detrimental (incompatible) genetic interactions between parental alleles that incur a fitness cost in hybrids. We reported on recessive hybrid incompatibility between an Arabidopsis thaliana strain from Poland, Landsberg erecta (Ler), and many Central Asian A. thaliana strains. The incompatible interaction is determined by a polymorphic cluster of Toll/interleukin-1 receptor-nucleotide binding-leucine rich repeat (TNL) RPP1 (Recognition of Peronospora parasitica1)-like genes in Ler and alleles of the receptor-like kinase Strubbelig Receptor Family 3 (SRF3) in Central Asian strains Kas-2 or Kond, causing temperature-dependent autoimmunity and loss of growth and reproductive fitness. Here, we genetically dissected the RPP1-like Ler locus to determine contributions of individual RPP1-like Ler (R1-R8) genes to the incompatibility. In a neutral background, expression of most RPP1-like Ler genes, except R3, has no effect on growth or pathogen resistance. Incompatibility involves increased R3 expression and engineered R3 overexpression in a neutral background induces dwarfism and sterility. However, no individual RPP1-like Ler gene is sufficient for incompatibility between Ler and Kas-2 or Kond, suggesting that co-action of at least two RPP1-like members underlies this epistatic interaction. We find that the RPP1-like Ler haplotype is frequent and occurs with other Ler RPP1-like alleles in a local population in Gorzów Wielkopolski (Poland). Only Gorzów individuals carrying the RPP1-like Ler haplotype are incompatible with Kas-2 and Kond, whereas other RPP1-like alleles in the population are compatible. Therefore, the RPP1-like Ler haplotype has been maintained in genetically different individuals at a single site, allowing exploration of forces shaping the evolution of RPP1-like genes at local and regional population scales. PMID:25503786

  4. Screening and Characterization of Mutations in Isoniazid-Resistant Mycobacterium tuberculosis Isolates Obtained in Brazil

    PubMed Central

    Cardoso, Rosilene Fressatti; Cooksey, Robert C.; Morlock, Glenn P.; Barco, Patricia; Cecon, Leticia; Forestiero, Francisco; Leite, Clarice Q. F.; Sato, Daisy N.; Shikama, Maria de Lourdes; Mamizuka, Elsa M.; Hirata, Rosario D. C.; Hirata, Mario H.

    2004-01-01

    We investigated mutations in the genes katG, inhA (regulatory and structural regions), and kasA and the oxyR-ahpC intergenic region of 97 isoniazid (INH)-resistant and 60 INH-susceptible Mycobacterium tuberculosis isolates obtained in two states in Brazil: São Paulo and Paraná. PCR-single-strand conformational polymorphism (PCR-SSCP) was evaluated for screening mutations in regions of prevalence, including codons 315 and 463 of katG, the regulatory region and codons 16 and 94 of inhA, kasA, and the oxyR-ahpC intergenic region. DNA sequencing of PCR amplicons was performed for all isolates with altered PCR-SSCP profiles. Mutations in katG were found in 83 (85.6%) of the 97 INH-resistant isolates, including mutations in codon 315 that occurred in 60 (61.9%) of the INH-resistant isolates and 23 previously unreported katG mutations. Mutations in the inhA promoter region occurred in 25 (25.8%) of the INH-resistant isolates; 6.2% of the isolates had inhA structural gene mutations, and 10.3% had mutations in the oxyR-ahpC intergenic region (one, nucleotide −48, previously unreported). Polymorphisms in the kasA gene occurred in both INH-resistant and INH-susceptible isolates. The most frequent polymorphism encoded a G269A substitution. Although KatG315 substitutions are predominant, novel mutations also appear to be responsible for INH resistance in the two states in Brazil. Since ca. 90.7% of the INH-resistant isolates had mutations identified by SSCP electrophoresis, this method may be a useful genotypic screen for INH resistance. PMID:15328099

  5. Prevalence of daidzein-metabolizing phenotypes differs between Caucasian and Korean American women and girls.

    PubMed

    Song, Kyung Bin; Atkinson, Charlotte; Frankenfeld, Cara L; Jokela, Tuija; Wähälä, Kristiina; Thomas, Wendy K; Lampe, Johanna W

    2006-05-01

    Interindividual differences in metabolism of the soy isoflavone, daidzein, to equol and O-desmethylangolensin (ODMA) by human gut bacteria, have been associated with altered risk of cancer and other chronic diseases, according to some studies. Differences have been reported in the prevalence of the equol-producer phenotype among populations, with a higher prevalence in soy-consuming Asian populations than in Western populations. To date, prevalence of the daidzein-metabolizing phenotypes in Asians, compared with Caucasians, has not been evaluated in the context of a standardized phenotyping method. We assessed the prevalence of equol- and ODMA-producer phenotypes in 91 Korean American (KA) women and girls living in the Seattle, Washington area and compared this with previous similarly collected prevalence data in Caucasian American (CA) women and girls (n = 222). We also compared the dietary habits of the 2 groups. Isoflavonoid concentrations in first-void morning urines, collected after a 3-d soy challenge, were used to establish equol-, and ODMA-producer phenotypes (>44 microg/L). The prevalence of the equol-producer phenotype was higher (51 vs. 36%; P = 0.015) and the ODMA-producer phenotype was lower (84 vs. 92%, P = 0.03) in KA than in CA women and girls. KAs consumed approximately 3 times more soy foods than the CAs, but no significant associations were found between the consumption of soy foods and equol-producer phenotype. Our findings support the reports that, compared with Western populations, Asian populations have a higher equol-producer prevalence. The additional observation that the prevalence of the ODMA-producer phenotype is lower in KAs suggests that daidzein-metabolizing patterns in general may differ between KAs and CAs. PMID:16614428

  6. Screening and characterization of mutations in isoniazid-resistant Mycobacterium tuberculosis isolates obtained in Brazil.

    PubMed

    Cardoso, Rosilene Fressatti; Cooksey, Robert C; Morlock, Glenn P; Barco, Patricia; Cecon, Leticia; Forestiero, Francisco; Leite, Clarice Q F; Sato, Daisy N; Shikama, Maria de Lourdes; Mamizuka, Elsa M; Hirata, Rosario D C; Hirata, Mario H

    2004-09-01

    We investigated mutations in the genes katG, inhA (regulatory and structural regions), and kasA and the oxyR-ahpC intergenic region of 97 isoniazid (INH)-resistant and 60 INH-susceptible Mycobacterium tuberculosis isolates obtained in two states in Brazil: São Paulo and Paraná. PCR-single-strand conformational polymorphism (PCR-SSCP) was evaluated for screening mutations in regions of prevalence, including codons 315 and 463 of katG, the regulatory region and codons 16 and 94 of inhA, kasA, and the oxyR-ahpC intergenic region. DNA sequencing of PCR amplicons was performed for all isolates with altered PCR-SSCP profiles. Mutations in katG were found in 83 (85.6%) of the 97 INH-resistant isolates, including mutations in codon 315 that occurred in 60 (61.9%) of the INH-resistant isolates and 23 previously unreported katG mutations. Mutations in the inhA promoter region occurred in 25 (25.8%) of the INH-resistant isolates; 6.2% of the isolates had inhA structural gene mutations, and 10.3% had mutations in the oxyR-ahpC intergenic region (one, nucleotide -48, previously unreported). Polymorphisms in the kasA gene occurred in both INH-resistant and INH-susceptible isolates. The most frequent polymorphism encoded a G(269)A substitution. Although KatG(315) substitutions are predominant, novel mutations also appear to be responsible for INH resistance in the two states in Brazil. Since ca. 90.7% of the INH-resistant isolates had mutations identified by SSCP electrophoresis, this method may be a useful genotypic screen for INH resistance. PMID:15328099

  7. Population genetics study of isoniazid resistance mutations and evolution of multidrug-resistant Mycobacterium tuberculosis.

    PubMed

    Hazbón, Manzour Hernando; Brimacombe, Michael; Bobadilla del Valle, Miriam; Cavatore, Magali; Guerrero, Marta Inírida; Varma-Basil, Mandira; Billman-Jacobe, Helen; Lavender, Caroline; Fyfe, Janet; García-García, Lourdes; León, Clara Inés; Bose, Mridula; Chaves, Fernando; Murray, Megan; Eisenach, Kathleen D; Sifuentes-Osornio, José; Cave, M Donald; Ponce de León, Alfredo; Alland, David

    2006-08-01

    The molecular basis for isoniazid resistance in Mycobacterium tuberculosis is complex. Putative isoniazid resistance mutations have been identified in katG, ahpC, inhA, kasA, and ndh. However, small sample sizes and related potential biases in sample selection have precluded the development of statistically valid and significant population genetic analyses of clinical isoniazid resistance. We present the first large-scale analysis of 240 alleles previously associated with isoniazid resistance in a diverse set of 608 isoniazid-susceptible and 403 isoniazid-resistant clinical M. tuberculosis isolates. We detected 12 mutant alleles in isoniazid-susceptible isolates, suggesting that these alleles are not involved in isoniazid resistance. However, mutations in katG, ahpC, and inhA were strongly associated with isoniazid resistance, while kasA mutations were associated with isoniazid susceptibility. Remarkably, the distribution of isoniazid resistance-associated mutations was different in isoniazid-monoresistant isolates from that in multidrug-resistant isolates, with significantly fewer isoniazid resistance mutations in the isoniazid-monoresistant group. Mutations in katG315 were significantly more common in the multidrug-resistant isolates. Conversely, mutations in the inhA promoter were significantly more common in isoniazid-monoresistant isolates. We tested for interactions among mutations and resistance to different drugs. Mutations in katG, ahpC, and inhA were associated with rifampin resistance, but only katG315 mutations were associated with ethambutol resistance. There was also a significant inverse association between katG315 mutations and mutations in ahpC or inhA and between mutations in kasA and mutations in ahpC. Our results suggest that isoniazid resistance and the evolution of multidrug-resistant strains are complex dynamic processes that may be influenced by interactions between genes and drug-resistant phenotypes. PMID:16870753

  8. Signature gene expression profiles discriminate between isoniazid-, thiolactomycin-, and triclosan-treated Mycobacterium tuberculosis.

    PubMed

    Betts, Joanna C; McLaren, Alistair; Lennon, Mark G; Kelly, Fiona M; Lukey, Pauline T; Blakemore, Steve J; Duncan, Ken

    2003-09-01

    Genomic technologies have the potential to greatly increase the efficiency of the drug development process. As part of our tuberculosis drug discovery program, we used DNA microarray technology to profile drug-induced effects in Mycobacterium tuberculosis. Expression profiles of M. tuberculosis treated with compounds that inhibit key metabolic pathways are required as references for the assessment of novel antimycobacterial agents. We have studied the response of M. tuberculosis to treatment with the mycolic acid biosynthesis inhibitors isoniazid, thiolactomycin, and triclosan. Thiolactomycin targets the beta-ketoacyl-acyl carrier protein (ACP) synthases KasA and KasB, while triclosan inhibits the enoyl-ACP reductase InhA. However, controversy surrounds the precise mode of action of isoniazid, with both InhA and KasA having been proposed as the primary target. We have shown that although the global response profiles of isoniazid and thiolactomycin are more closely related to each other than to that of triclosan, there are differences that distinguish the mode of action of these two drugs. In addition, we have identified two groups of genes, possibly forming efflux and detoxification systems, through which M. tuberculosis may limit the effects of triclosan. We have developed a mathematical model, based on the expression of 21 genes, which is able to perfectly discriminate between isoniazid-, thiolactomycin-, or triclosan-treated M. tuberculosis. This model is likely to prove invaluable as a tool to improve the efficiency of our drug development programs by providing a means to rapidly confirm the mode of action of thiolactomycin analogues or novel InhA inhibitors as well as helping to translate enzyme activity into whole-cell activity. PMID:12936993

  9. Fatty Acid Biosynthesis in Pseudomonas aeruginosa Is Initiated by the FabY Class of β-Ketoacyl Acyl Carrier Protein Synthases

    PubMed Central

    Yuan, Yanqiu; Sachdeva, Meena; Leeds, Jennifer A.

    2012-01-01

    The prototypical type II fatty acid synthesis (FAS) pathway in bacteria utilizes two distinct classes of β-ketoacyl synthase (KAS) domains to assemble long-chain fatty acids, the KASIII domain for initiation and the KASI/II domain for elongation. The central role of FAS in bacterial viability and virulence has stimulated significant effort toward developing KAS inhibitors, particularly against the KASIII domain of the β-acetoacetyl-acyl carrier protein (ACP) synthase FabH. Herein, we show that the opportunistic pathogen Pseudomonas aeruginosa does not utilize a FabH ortholog but rather a new class of divergent KAS I/II enzymes to initiate the FAS pathway. When a P. aeruginosa cosmid library was used to rescue growth in a fabH downregulated strain of Escherichia coli, a single unannotated open reading frame, PA5174, complemented fabH depletion. While deletion of all four KASIII domain-encoding genes in the same P. aeruginosa strain resulted in a wild-type growth phenotype, deletion of PA5174 alone specifically attenuated growth due to a defect in de novo FAS. Siderophore secretion and quorum-sensing signaling, particularly in the rhl and Pseudomonas quinolone signal (PQS) systems, was significantly muted in the absence of PA5174. The defect could be repaired by intergeneric complementation with E. coli fabH. Characterization of recombinant PA5174 confirmed a preference for short-chain acyl coenzyme A (acyl-CoA) substrates, supporting the identification of PA5174 as the predominant enzyme catalyzing the condensation of acetyl coenzyme A with malonyl-ACP in P. aeruginosa. The identification of the functional role for PA5174 in FAS defines the new FabY class of β-ketoacyl synthase KASI/II domain condensation enzymes. PMID:22753059

  10. Rutile solubility and titanium coordination in silicate melts

    NASA Astrophysics Data System (ADS)

    Dickinson, James E., Jr.; Hess, Paul C.

    1985-11-01

    The solubility of rutile has been determined in a series of compositions in the K 2O-Al 2O 3-SiO 2 system ( K ∗ = K 2O /(K 2O + Al 2O 3) = 0.38-0.90), and the CaO-Al 2O 3-SiO 2 system ( C ∗ = CaO/(CaO + Al 2O 3) = 0.47-0.59 ). Isothermal results in the KAS system at 1325°C, 1400°C, and 1475°C show rutile solubility to be a strong function of the K ∗ ratio. For example, at 1475°C the amount of TiO 2 required for rutile saturation varies from 9.5 wt% ( K ∗ = 0.38 ) to 11.5 wt% ( K ∗ = 0.48 ) to 41.2 wt% ( K ∗ = 0.90 ). In the CAS system at 1475°C, rutile solubility is not a strong function of C ∗. The amount of TiO 2 required for saturation varies from 14 wt% ( C ∗ = 0.48 ) to 16.2 wt% ( C ∗ = 0.59 ). The solubility changes in KAS melts are interpreted to be due to the formation of strong complexes between Ti and K + in excess of that needed to charge balance Al 3+. The suggested stoichiometry of this complex is K 2Ti 2O 5 or K 2Ti 3O 7. In CAS melts, the data suggest that Ca 2+ in excess of A1 3+ is not as effective at complexing with Ti as is K +. The greater solubility of rutile in CAS melts when C ∗ is less than 0.54 compared to KAS melts of equal K ∗ ratio results primarily from competition between Ti and Al for complexing cations (Ca vs. K). TiK β x-ray emission spectra of KAS glasses ( K ∗ = 0.43-0.60 ) with 7 mole% added TiO 2, rutile, and Ba 2TiO 4, demonstrate that the average Ti-O bond length in these glasses is equal to that of rutile rather than Ba 2TiO 4, implying that Ti in these compositions is 6-fold rather than 4-fold coordinated. Re-examination of published spectroscopic data in light of these results and the solubility data, suggests that the 6-fold coordination polyhedron of Ti is highly distorted, with at least one Ti-O bond grossly undersatisfied in terms of Pauling's rules.

  11. Contribution of dfrA and inhA Mutations to the Detection of Isoniazid-Resistant Mycobacterium tuberculosis Isolates▿

    PubMed Central

    Ho, Yu Min; Sun, Yong-Jiang; Wong, Sin-Yew; Lee, Ann S. G.

    2009-01-01

    Screening of 127 isoniazid (INH)-resistant Mycobacterium tuberculosis isolates from Singapore for mutations within the dfrA and inhA genes revealed mutations in 0 and 5 (3.9%) isolates respectively, implying that mutations in dfrA do not contribute to the detection of INH-resistant M. tuberculosis and that mutations within inhA are rare. Thirty-seven (29%) of the 127 isolates had no mutations in any of the genes implicated in INH resistance (katG, kasA, and ndh; inhA and ahpC promoters), suggesting that there are new INH targets yet to be discovered. PMID:19581462

  12. Translation and Validation of the Dietary Approaches to Stop Hypertension for Koreans Intervention

    PubMed Central

    Kim, Hyerang; Song, Hee-Jung; Han, Hae-Ra; Kim, Kim B.; Kim, Miyong T.

    2015-01-01

    Background Lifestyle modification strategies such as adoption of the Dietary Approaches to Stop Hypertension (DASH) diet are now recognized as an integral part of high blood pressure (HBP) management. Although the high prevalence of HBP among Korean Americans (KAs) is well documented, few dietary interventions have been implemented in this population, in part because of a lack of culturally relevant nutrition education guidelines. Translating and testing the efficacy of culturally relevant dietary recommendations using a well-established dietary guideline such as DASH are imperative for promoting better cardiovascular health for this high-risk cultural group. Objective The aims of this study were to systematically translate and validate a culturally modified DASH for Koreans (K-DASH) and obtain preliminary evidence of efficacy. Methods A 2-step approach of intervention translation and efficacy testing, together with close adherence to principles of community-based participatory research, was used to maximize community input. A 1-group pre-post design with 24-hour urine and 24-hour ambulatory blood pressure monitoring comparisons was used to test the initial feasibility and efficacy of the K-DASH intervention. Results A total of 28 KAs with HBP participated in a 10-week dietary intervention consisting of group education sessions and individual counseling. Both systolic blood pressure and diastolic blood pressure, as measured by ambulatory blood pressure monitoring, were significantly decreased at postintervention evaluation (systolic blood pressure, −4.5 mm Hg; diastolic blood pressure, −2.6 mm Hg; P < .05). Serum low-density lipoprotein cholesterol was significantly decreased (−7.3 mg/dL; P < .05). Serum potassium and ascorbic acid levels were also improved in the reference range. Urine potassium level was significantly increased, supporting increased fruit and vegetable consumption. Conclusion This pilot study has (a) demonstrated that a cultural adaptation

  13. Carboxyl pKa Values, Ion Pairs, Hydrogen Bonding, and the pH Dependence of Folding the Hyperthermophile Proteins Sac7d and Sso7d

    PubMed Central

    Clark, Andrew T.; Smith, Kelley; Muhandiram, Ranjith; Edmondson, Stephen P.; Shriver, John W.

    2007-01-01

    Sac7d and Sso7d are homologous, hyperthermophile proteins with a high density of charged surface residues and potential ion pairs. To determine the relative importance of specific amino acid side chains in defining the stability and function of these Archaeal chromatin proteins, pKas were measured for all of the acidic residues in both proteins using 13C NMR chemical shifts. The stability of Sso7d enabled titrations to pH 1 under low salt conditions. Two aspartate residues in Sso7d (D16 and D35) and a single glutamate residue (G54) showed significantly perturbed pKa values in low salt, indicating that the observed pH dependence of stability was primarily due to these three residues. The pH dependence of backbone amide NMR resonances demonstrated that perturbation of all three pKas was primarily the result of side chain-backbone amide hydrogen bonds. Titration data at higher salt for both Sso7d and Sac7d were consistent with this interpretation. Few of the significantly perturbed acidic pKas in Sac7d and Sso7d could be attributed to primarily ion pair or electrostatic interactions. A smaller perturbation of E48 (E47 in Sac7d) was ascribed to an ion pair interaction that may be important in defining the DNA binding surface. The small number (3) of significantly altered pKa values was in good agreement with a linkage analysis of the temperature, pH, and salt dependence of folding. The linkage of the ionization of two or more side chains to protein folding leads to apparent cooperativity in the pH dependence of folding, although each group titrates independently with a Hill coefficient near unity. These results demonstrate that the acid pH dependence of protein stability in these hyperthermophile proteins is due to independent titration of acidic residues with pKas perturbed primarily by hydrogen bonding of the side chain to the backbone. This work demonstrates the need for caution in using structural data alone to argue the importance of ion pairs in stabilizing

  14. Colorado State University program for developing, testing, evaluating and optimizing solar heating and cooling systems: Project status report for the months of October and November, 1994

    SciTech Connect

    Not Available

    1994-12-01

    This report describes a project to develop tools for evaluating solar heating and cooling systems. Current work on this project has been to validate the Florida Solar Energy Center`s (FSEC) models of the Solahart 302K and 302K-AS systems to prepare a rating for the Sacramento Municipal Utility District`s rebate program for solar domestic hot water heaters. A preliminary rating has been issued by FSEC and updated ratings will be released as necessary. Two of the problems that were mentioned in the August/September report are addressed and a tank heat loss test is discussed. Work continues on improving and validating the models.

  15. Evidence of Clonal Expansion in the Genome of a Multidrug-Resistant Mycobacterium tuberculosis Clinical Isolate from Peru.

    PubMed

    Galarza, M; Tarazona, D; Borda, V; Agapito, J C; Guio, H

    2014-01-01

    We report the genome sequence of Mycobacterium tuberculosis INS-MDR from Peru, a multidrug-resistant tuberculosis (MDR-TB) and Latin American-Mediterranean (LAM) lineage strain. Our analysis showed mutations related to drug resistance in the rpoB (D516V), katG (S315T), kasA (G269S), and pncA (Q10R) genes. Our evidence suggests that INS-MDR may be a clonal expansion related to the African strain KZN 1435. PMID:24578270

  16. Contribution of dfrA and inhA mutations to the detection of isoniazid-resistant Mycobacterium tuberculosis isolates.

    PubMed

    Ho, Yu Min; Sun, Yong-Jiang; Wong, Sin-Yew; Lee, Ann S G

    2009-09-01

    Screening of 127 isoniazid (INH)-resistant Mycobacterium tuberculosis isolates from Singapore for mutations within the dfrA and inhA genes revealed mutations in 0 and 5 (3.9%) isolates respectively, implying that mutations in dfrA do not contribute to the detection of INH-resistant M. tuberculosis and that mutations within inhA are rare. Thirty-seven (29%) of the 127 isolates had no mutations in any of the genes implicated in INH resistance (katG, kasA, and ndh; inhA and ahpC promoters), suggesting that there are new INH targets yet to be discovered. PMID:19581462

  17. [New technologies in the determination of drug susceptibility in Mycobacterium tuberculosis].

    PubMed

    Skotnikova, O I; Mikhaĭlovich, V M; Nosova, E Iu; Lapa, S A; Griadunov, D A; Donnikov, M Iu; Badleeva, M V; Galkina, K Iu; Dorozhkova, I R; Litvinov, V I; Zasedatelev, A S; Moroz, A M; Mirzabekov, A D

    2004-01-01

    A variety of mutations in the genes rpoB, katG, inhA, ahpC, kasA was studied by using different molecular biological methods (conformational polymorphism of single-chain fragments, heteroduplex analysis, biochips) in rifampicin- and isoniazid-resistant Mycobacterium tuberculosis (MBT) strains isolated from patients with pulmonary tuberculosis. Twenty-nine mutation combinations were identified in the MBT strains. The use of biochips is the most promising method for identifying the type of mutations responsible for the simultaneous resistance to rifampicin and isoniazid. Detection of several MBT strains in one patient requires the use a combination of molecular biological and microbiological studies. PMID:15315132

  18. Novel mutations in ndh in isoniazid-resistant Mycobacterium tuberculosis isolates.

    PubMed

    Lee, A S; Teo, A S; Wong, S Y

    2001-07-01

    Novel mutations in NADH dehydrogenase (ndh) were detected in 8 of 84 (9.5%) isoniazid (INH)-resistant isolates (T110A [n = 1], R268H [n = 7]), but not in 22 INH-susceptible isolates of Mycobacterium tuberculosis. Significantly, all eight isolates with mutations at ndh did not have mutations at katG, kasA, or the promoter regions of inhA or ahpC, except for one isolate. Mutations in ndh appear to be an additional molecular mechanism for isoniazid resistance in M. tuberculosis. PMID:11408244

  19. Evidence of Clonal Expansion in the Genome of a Multidrug-Resistant Mycobacterium tuberculosis Clinical Isolate from Peru

    PubMed Central

    Galarza, M.; Tarazona, D.; Borda, V.; Agapito, J. C.

    2014-01-01

    We report the genome sequence of Mycobacterium tuberculosis INS-MDR from Peru, a multidrug-resistant tuberculosis (MDR-TB) and Latin American-Mediterranean (LAM) lineage strain. Our analysis showed mutations related to drug resistance in the rpoB (D516V), katG (S315T), kasA (G269S), and pncA (Q10R) genes. Our evidence suggests that INS-MDR may be a clonal expansion related to the African strain KZN 1435. PMID:24578270

  20. Expression of fatty acid synthesis genes and fatty acid accumulation in haematococcus pluvialis under different stressors

    PubMed Central

    2012-01-01

    Background Biofuel has been the focus of intensive global research over the past few years. The development of 4th generation biofuel production (algae-to-biofuels) based on metabolic engineering of algae is still in its infancy, one of the main barriers is our lacking of understanding of microalgal growth, metabolism and biofuel production. Although fatty acid (FA) biosynthesis pathway genes have been all cloned and biosynthesis pathway was built up in some higher plants, the molecular mechanism for its regulation in microalgae is far away from elucidation. Results We cloned main key genes for FA biosynthesis in Haematococcus pluvialis, a green microalga as a potential biodiesel feedstock, and investigated the correlations between their expression alternation and FA composition and content detected by GC-MS under different stress treatments, such as nitrogen depletion, salinity, high or low temperature. Our results showed that high temperature, high salinity, and nitrogen depletion treatments played significant roles in promoting microalgal FA synthesis, while FA qualities were not changed much. Correlation analysis showed that acyl carrier protein (ACP), 3-ketoacyl-ACP-synthase (KAS), and acyl-ACP thioesterase (FATA) gene expression had significant correlations with monounsaturated FA (MUFA) synthesis and polyunsaturated FA (PUFA) synthesis. Conclusions We proposed that ACP, KAS, and FATA in H. pluvialis may play an important role in FA synthesis and may be rate limiting genes, which probably could be modified for the further study of metabolic engineering to improve microalgal biofuel quality and production. PMID:22448811

  1. Trimerization of Phenyl Cyanate Ester

    NASA Astrophysics Data System (ADS)

    Pallaka, Madhusudhan Reddy; Simon, Sindee L.

    2015-03-01

    The kinetics of phenyl cyanate ester trimerization is studied in the bulk using differential scanning calorimetry. Dynamic experiments for different heating rates are analyzed for the activation energy using the model-free Kissinger-Akahira-Sunose(KAS) isoconversion method. The activation energy and other kinetic parameters are also obtained by fitting the dynamic data to a first order autocatalytic reaction model, which well describes the experimental data. The activation energy obtained from the KAS isoconversion method (70.1 kJ/mol) is in good agreement with that obtained from the kinetic model (73.2 kJ/mol) and is much lower than the more bulky cyanate esters studied in our laboratory, which have activation energies of approximately 95 kJ/mol. In addition, the rate constant for the phenyl cyanate ester is one to two orders higher than the bulkier cyanate esters in the temperature range of 200 to 300°C. Further elucidation of the dynamic experiments revealed a strong dependence of the reaction kinetics on the sample weight. Future work aims to understand this finding.

  2. Shewanella oneidensis FabB: A β-ketoacyl-ACP Synthase That Works with C16:1-ACP

    PubMed Central

    Luo, Qixia; Li, Meng; Fu, Huihui; Meng, Qiu; Gao, Haichun

    2016-01-01

    It is established that Escherichia coli β-ketoacyl-ACP synthase (KAS) I (encoded by EcfabB) is the primary, if not exclusive, factor for elongation of the cis-3-decenoyl-ACP (C10:1-ACP) but not effective with C16:1- or longer-chain-ACPs. To test the extent to which these features apply to KAS I proteins in other species, in this study, we examined the physiological role of FabB in Shewanella oneidensis, an excellent model for researching type II fatty acid synthetic (FAS) system and its regulation. We showed that the loss of either FabA (the enzyme that introduces double bond) or FabB, in the absence of DesA which desaturizes C16 and C18 to generate respective C16:1 and C18:1, leads to a UFA auxotroph. However, fatty acid profiles of membrane phospholipid of the fabA and fabB mutants are significantly different, suggesting that FabB participates in steps beyond elongation of C10:1-ACP. Further analyses demonstrated that S. oneidensis FabB differs from EcFabB in that (i) it is not the only enzyme capable of catalyzing elongation of the cis-3-decenoyl-ACP produced by FabA, (ii) it plays a critical role in elongation of C16:1- and longer-chain-ACPs, and (iii) its overproduction is detrimental. PMID:27014246

  3. The Role of p16, p21, p27, p53 and Ki-67 Expression in the Differential Diagnosis of Cutaneous Squamous Cell Carcinomas and Keratoacanthomas: An Immunohistochemical Study

    PubMed Central

    Bedir, Recep; Güçer, Hasan; Şehitoğlu, İbrahim; Yurdakul, Cüneyt; Bağcı, Pelin; Üstüner, Pelin

    2016-01-01

    Background: Distinguishing squamous cell carcinoma (SCC) from keratoacanthoma (KA) by histopathological features may not be sufficient for a differential diagnosis, as KAs may, in some cases, imitate well-differentiated SCCs. Aims: In this study, we investigated whether the expression of the p16, p21, p27, p53 genes and a Ki-67 proliferation index are useful in distinguishing between these two tumors. Study Design: Cross-sectional study. Methods: Immunohistochemistry was used to investigate the expression of the p16, p21, p27, p53 genes and the Ki-67 proliferation index was investigated in well-differentiated SCC with KA-like features (n=40) and KA (n=30). Results: The results of all of the examined markers, except for p27 (p16, p21, p53, and Ki-67) were found to be significantly different between the SCC and KA samples (p<0.05). Conclusion: In well-differentiated SCC with KA-like features and KA cases where the differential diagnosis is difficult from a histopathological perspective, the use of p16, p21, p53 expression and a Ki-67 proliferation index can be useful for the differential diagnosis of SCCs and KAs. PMID:27403379

  4. Identification of Gene-Specific Polymorphisms and Association with Capsaicin Pathway Metabolites in Capsicum annuum L. Collections

    PubMed Central

    Abburi, Venkata L.; Alaparthi, Suresh Babu; Unselt, Desiree; Hankins, Gerald; Park, Minkyu; Choi, Doil

    2014-01-01

    Pepper (Capsicum annuum L.) is an economically important crop with added nutritional value. Production of capsaicin is an important quantitative trait with high environmental variance, so the development of markers regulating capsaicinoid accumulation is important for pepper breeding programs. In this study, we performed association mapping at the gene level to identify single nucleotide polymorphisms (SNPs) associated with capsaicin pathway metabolites in a diverse Capsicum annuum collection during two seasons. The genes Pun1, CCR, KAS and HCT were sequenced and matched with the whole-genome sequence draft of pepper to identify SNP locations and for further characterization. The identified SNPs for each gene underwent candidate gene association mapping. Association mapping results revealed Pun1 as a key regulator of major metabolites in the capsaicin pathway mainly affecting capsaicinoids and precursors for acyl moieties of capsaicinoids. Six different SNPs in the promoter sequence of Pun1 were found associated with capsaicin in plants from both seasons. Our results support that CCR is an important control point for the flux of p-coumaric acid to specific biosynthesis pathways. KAS was found to regulate the major precursors for acyl moieties of capsaicinoids and may play a key role in capsaicinoid production. Candidate gene association mapping of Pun1 suggested that the accumulation of capsaicinoids depends on the expression of Pun1, as revealed by the most important associated SNPs found in the promoter region of Pun1. PMID:24475113

  5. Computational Tools for Interpreting Ion Channel pH-Dependence

    PubMed Central

    Sazanavets, Ivan; Warwicker, Jim

    2015-01-01

    Activity in many biological systems is mediated by pH, involving proton titratable groups with pKas in the relevant pH range. Experimental analysis of pH-dependence in proteins focusses on particular sidechains, often with mutagenesis of histidine, due to its pKa near to neutral pH. The key question for algorithms that predict pKas is whether they are sufficiently accurate to effectively narrow the search for molecular determinants of pH-dependence. Through analysis of inwardly rectifying potassium (Kir) channels and acid-sensing ion channels (ASICs), mutational effects on pH-dependence are probed, distinguishing between groups described as pH-coupled or pH-sensor. Whereas mutation can lead to a shift in transition pH between open and closed forms for either type of group, only for pH-sensor groups does mutation modulate the amplitude of the transition. It is shown that a hybrid Finite Difference Poisson-Boltzmann (FDPB) – Debye-Hückel continuum electrostatic model can filter mutation candidates, providing enrichment for key pH-coupled and pH-sensor residues in both ASICs and Kir channels, in comparison with application of FDPB alone. PMID:25915903

  6. Computational Tools for Interpreting Ion Channel pH-Dependence.

    PubMed

    Sazanavets, Ivan; Warwicker, Jim

    2015-01-01

    Activity in many biological systems is mediated by pH, involving proton titratable groups with pKas in the relevant pH range. Experimental analysis of pH-dependence in proteins focusses on particular sidechains, often with mutagenesis of histidine, due to its pKa near to neutral pH. The key question for algorithms that predict pKas is whether they are sufficiently accurate to effectively narrow the search for molecular determinants of pH-dependence. Through analysis of inwardly rectifying potassium (Kir) channels and acid-sensing ion channels (ASICs), mutational effects on pH-dependence are probed, distinguishing between groups described as pH-coupled or pH-sensor. Whereas mutation can lead to a shift in transition pH between open and closed forms for either type of group, only for pH-sensor groups does mutation modulate the amplitude of the transition. It is shown that a hybrid Finite Difference Poisson-Boltzmann (FDPB) - Debye-Hückel continuum electrostatic model can filter mutation candidates, providing enrichment for key pH-coupled and pH-sensor residues in both ASICs and Kir channels, in comparison with application of FDPB alone. PMID:25915903

  7. Evaluation of the Uniform Field Distortions Produced by a Toroidal Dielectric Body / Novērtējums Viendabīga Elektriskā Lauka Izkropļojumiem, Kurus Rada Toroīda Formas Dielektrisks Ķermenis

    NASA Astrophysics Data System (ADS)

    Krasnitsky, Y. A.; Popov, A. E.; Kalnacs, A.

    2015-08-01

    Distortions of the structure of a uniform electric field when a dielectric body with a toroidal shape is placed in it are considered in the quasi-static approximation. The rate of distortion is proposed to estimate through the effective permittivity of toroid determined by solving the corresponding boundary value problem. Some numerical estimates obtained using specially developed software in the language of Matlab are given. Darbā apskatīts kvazi-statisks tuvinājums viendabīga elektriskā lauka izkropļojumiem gadījumos, kad tajā tiek ievietots dielektrisks toroīda formas ķermenis. Izkropļojumu apmēru tiek piedāvāts novērtēt ar toroīda efektīvo caurlaidību, kas tiek noteikta, atrisinot atbilstošo robežvērtību uzdevumu. Tiek doti skaitliski novērtējumi, kas iegūti, lietojot speciāli valodā Matlab izstrādātu programmatūru.

  8. Kinetic modelling of RDF pyrolysis: Model-fitting and model-free approaches.

    PubMed

    Çepelioğullar, Özge; Haykırı-Açma, Hanzade; Yaman, Serdar

    2016-02-01

    In this study, refuse derived fuel (RDF) was selected as solid fuel and it was pyrolyzed in a thermal analyzer from room temperature to 900°C at heating rates of 5, 10, 20, and 50°C/min in N2 atmosphere. The obtained thermal data was used to calculate the kinetic parameters using Coats-Redfern, Friedman, Flylnn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. As a result of Coats-Redfern model, decomposition process was assumed to be four independent reactions with different reaction orders. On the other hand, model free methods demonstrated that activation energy trend had similarities for the reaction progresses of 0.1, 0.2-0.7 and 0.8-0.9. The average activation energies were found between 73-161kJ/mol and it is possible to say that FWO and KAS models produced closer results to the average activation energies compared to Friedman model. Experimental studies showed that RDF may be a sustainable and promising feedstock for alternative processes in terms of waste management strategies. PMID:26613830

  9. The Mycobacterium tuberculosis FAS-II condensing enzymes: their role in mycolic acid biosynthesis, acid-fastness, pathogenesis and in future drug development.

    PubMed

    Bhatt, Apoorva; Molle, Virginie; Besra, Gurdyal S; Jacobs, William R; Kremer, Laurent

    2007-06-01

    Mycolic acids are very long-chain fatty acids representing essential components of the mycobacterial cell wall. Considering their importance, characterization of key enzymes participating in mycolic acid biosynthesis not only allows an understanding of their role in the physiology of mycobacteria, but also might lead to the identification of new drug targets. Mycolates are synthesized by at least two discrete elongation systems, the type I and type II fatty acid synthases (FAS-I and FAS-II respectively). Among the FAS-II components, the condensing enzymes that catalyse the formation of carbon-carbon bonds have received considerable interest. Four condensases participate in initiation (mtFabH), elongation (KasA and KasB) and termination (Pks13) steps, leading to full-length mycolates. We present the recent biochemical and structural data for these important enzymes. Special emphasis is given to their role in growth, intracellular survival, biofilm formation, as well as in the physiopathology of tuberculosis. Recent studies demonstrated that phosphorylation of these enzymes by mycobacterial kinases affects their activities. We propose here a model in which kinases that sense environmental changes can phosphorylate the condensing enzymes, thus representing a novel mechanism of regulating mycolic acid biosynthesis. Finally, we discuss the attractiveness of these enzymes as valid targets for future antituberculosis drug development. PMID:17555433

  10. GroEL1: a dedicated chaperone involved in mycolic acid biosynthesis during biofilm formation in mycobacteria.

    PubMed

    Ojha, Anil; Anand, Mridula; Bhatt, Apoorva; Kremer, Laurent; Jacobs, William R; Hatfull, Graham F

    2005-12-01

    Mycobacteria are unusual in encoding two GroEL paralogs, GroEL1 and GroEL2. GroEL2 is essential--presumably providing the housekeeping chaperone functions--while groEL1 is nonessential, contains the attB site for phage Bxb1 integration, and encodes a putative chaperone with unusual structural features. Inactivation of the Mycobacterium smegmatis groEL1 gene by phage Bxb1 integration allows normal planktonic growth but prevents the formation of mature biofilms. GroEL1 modulates synthesis of mycolates--long-chain fatty acid components of the mycobacterial cell wall--specifically during biofilm formation and physically associates with KasA, a key component of the type II Fatty Acid Synthase involved in mycolic acid synthesis. Biofilm formation is associated with elevated synthesis of short-chain (C56-C68) fatty acids, and strains with altered mycolate profiles--including an InhA mutant resistant to the antituberculosis drug isoniazid and a strain overexpressing KasA--are defective in biofilm formation. PMID:16325580

  11. The β-ketoacyl-ACP synthase from Mycobacterium tuberculosis as potential drug targets.

    PubMed

    Singh, V; Mani, I; Chaudhary, D K; Somvanshi, P

    2011-01-01

    The continuous preventive measures and control of tuberculosis are often hampered by re-emergence of multi-drug-resistant (MDR) strains of Mycobacterium tuberculosis. A novel drug approach is desperately needed to combat the global threat posed by MDR strains. In spite of current advancement in biological techniques viz. microarray and proteomics data for tuberculosis, no such potent drug has been developed in the past decades yet. Therefore, mycolic acid is an essential constituent which is involved in the formation of cell wall of Mycobacterium species. The biosynthesis of mycolic acid is involved in two fatty acid synthase systems, the multifunctional polypeptide fatty acid synthase I (FASI) which performs de novo fatty acid synthesis and dissociate FASII system. FASII system consists of monofunctional enzymes and acyl carrier protein (ACP), elongating FASI products to long chain mycolic acid precursor. In this review, the β-ketoacyl-ACP synthases (fadH, kasA and kasB) are distinct and play a vital role in mycolic acid synthesis, cell wall synthesis, biofilm formation and also pathogenesis. On the basis of substantial observation we suggest that these enzymes may be used as promising and attractive targets for novel anti-TB drugs designing and discovery. PMID:21370994

  12. Molecular analysis of isoniazid-resistant clinical isolates of Mycobacterium tuberculosis from India.

    PubMed

    Nusrath Unissa, A; Selvakumar, N; Narayanan, Sujatha; Narayanan, P R

    2008-01-01

    The presence of mutations in specific regions of katG, inhA, oxyR-ahpC and kasA associated with isoniazid (INH)-resistant clinical isolates of Mycobacterium tuberculosis from India were analysed by DNA sequencing. Point mutations in the katG gene at codon 315 and a mutation at codon 138 were detected in 64.3% (45/70) and 4% (1/25) of isolates, respectively. Polymorphisms at codon 463 of the katG gene were found both in resistant and sensitive isolates. Mutation at the inhA and oxyR-ahpC promoter regions occurred in 11.4% (8/70) and 35.0% (14/40) of the isolates, respectively. No mutation was found to occur in kasA and inhA structural gene regions. Of the 70 resistant isolates studied, 55 (78.6%) showed mutation in the regions sequenced. This is the first comprehensive molecular analysis of INH resistance in India, which suggests that point mutation rather than deletion and insertion is the major cause of INH resistance. PMID:18006278

  13. Comparative metabolic profiling of mce1 operon mutant vs wild-type Mycobacterium tuberculosis strains.

    PubMed

    Queiroz, Adriano; Medina-Cleghorn, Daniel; Marjanovic, Olivera; Nomura, Daniel K; Riley, Lee W

    2015-11-01

    Mycobacterium tuberculosis disrupted in a 13-gene operon (mce1) accumulates free mycolic acids (FM) in its cell wall and causes accelerated death in mice. Here, to more comprehensively analyze differences in their cell wall lipid composition, we used an untargeted metabolomics approach to compare the lipid profiles of wild-type and mce1 operon mutant strains. By liquid chromatography-mass spectrometry, we identified >400 distinct lipids significantly altered in the mce1 mutant compared to wild type. These lipids included decreased levels of saccharolipids and glycerophospholipids, and increased levels of alpha-, methoxy- and keto mycolic acids (MA), and hydroxyphthioceranic acid. The mutant showed reduced expression of mmpL8, mmpL10, stf0, pks2 and papA2 genes involved in transport and metabolism of lipids recognized to induce proinflammatory response; these lipids were found to be decreased in the mutant. In contrast, the transcripts of mmpL3, fasI, kasA, kasB, acpM and RV3451 involved in MA transport and metabolism increased; MA inhibits inflammatory response in macrophages. Since the mce1 operon is known to be regulated in intracellular M. tuberculosis, we speculate that the differences we observed in cell wall lipid metabolism and composition may affect host response to M. tuberculosis infection and determine the clinical outcome of such an infection. PMID:26319139

  14. New approaches to target the mycolic acid biosynthesis pathway for the development of tuberculosis therapeutics.

    PubMed

    North, E Jeffrey; Jackson, Mary; Lee, Richard E

    2014-01-01

    Mycolic acids are the major lipid components of the unique mycobacterial cell wall responsible for the protection of the tuberculosis bacilli from many outside threats. Mycolic acids are synthesized in the cytoplasm and transported to the outer membrane as trehalose- containing glycolipids before being esterified to the arabinogalactan portion of the cell wall and outer membrane glycolipids. The large size of these unique fatty acids is a result of a huge metabolic investment that has been evolutionarily conserved, indicating the importance of these lipids to the mycobacterial cellular survival. There are many key enzymes involved in the mycolic acid biosynthetic pathway, including fatty acid synthesis (KasA, KasB, MabA, InhA, HadABC), mycolic acid modifying enzymes (SAM-dependent methyltransferases, aNAT), fatty acid activating and condensing enzymes (FadD32, Acc, Pks13), transporters (MmpL3) and tranferases (Antigen 85A-C) all of which are excellent potential drug targets. Not surprisingly, in recent years many new compounds have been reported to inhibit specific portions of this pathway, discovered through both phenotypic screening and target enzyme screening. In this review, we analyze the new and emerging inhibitors of this pathway discovered in the post-genomic era of tuberculosis drug discovery, several of which show great promise as selective tuberculosis therapeutics. PMID:24245756

  15. Mycobacterium tuberculosis SigM positively regulates Esx secreted protein and nonribosomal peptide synthetase genes and down regulates virulence-associated surface lipid synthesis.

    PubMed

    Raman, Sahadevan; Puyang, Xiaoling; Cheng, Tan-Yun; Young, David C; Moody, D Branch; Husson, Robert N

    2006-12-01

    The Mycobacterium tuberculosis genome encodes 12 alternative sigma factors, several of which regulate stress responses and are required for virulence in animal models of acute infection. In this work we investigated M. tuberculosis SigM, a member of the extracytoplasmic function subfamily of alternative sigma factors. This sigma factor is expressed at low levels in vitro and does not appear to function in stress response regulation. Instead, SigM positively regulates genes required for the synthesis of surface or secreted molecules. Among these are genes encoding two pairs of Esx secreted proteins, a multisubunit nonribosomal peptide synthetase operon, and genes encoding two members of the proline-proline-glutamate (PPE) family of proteins. Genes up regulated in a sigM mutant strain include a different PPE gene, as well as several genes involved in surface lipid synthesis. Among these are genes involved in synthesis of phthiocerol dimycocerosate (PDIM), a surface lipid critical for virulence during acute infection, and the kasA-kasB operon, which is required for mycolic acid synthesis. Analysis of surface lipids showed that PDIM synthesis is increased in a sigM-disrupted strain and is undetectable in a sigM overexpression strain. These findings demonstrate that SigM positively and negatively regulates cell surface and secreted molecules that are likely to function in host-pathogen interactions. PMID:17028284

  16. New Approaches to Target the Mycolic Acid Biosynthesis Pathway for the Development of Tuberculosis Therapeutics

    PubMed Central

    North, E. Jeffrey; Jackson, Mary; Lee, Richard E.

    2015-01-01

    Mycolic acids are the major lipid component of the unique mycobacterial cell wall responsible for the protection of the tuberculosis bacilli from many outside threats. Mycolic acids are synthesized in the cytoplasm and transported to the outer membrane as trehalose-containing glycolipids before being esterified to the arabinogalactan portion of the cell wall and outer membrane glycolipids. The large size of these unique fatty acids is a result of a huge metabolic investment that has been evolutionarily conserved, indicating the importance of these lipids to the mycobacterial cellular survival. There are many key enzymes involved in the mycolic acid biosynthetic pathway, including fatty acid synthesis (KasA, KasB, MabA, InhA, HadABC), mycolic acid modifying enzymes (SAM-dependent methyltransferases, aNAT), fatty acid activating and condensing enzymes (FadD32, Acc, Pks13), transporters (MmpL3) and tranferases (Antigen 85A-C) all of which are excellent potential drug targets. Not surprisingly, in recent years many new compounds have been reported to inhibit specific portions of this pathway, discovered through both phenotypic screening and target enzyme screening. In this review, we analyze the new and emerging inhibitors of this pathway discovered in the post-genomic era of tuberculosis drug discovery, several of which show great promise as selective tuberculosis therapeutics. PMID:24245756

  17. HPV 6-positive giant keratoacanthoma in an immunocompetent patient.

    PubMed

    Saftic, Marina; Batinac, Tanja; Zamolo, Gordana; Coklo, Miran; Simat, Marina; Mustac, Elvira; Bosnar, Alan; Grahovac, Blazenka

    2006-01-01

    Keratoacanthoma (KA) is a clinically distinct, rapidly growing lesion that generally presents as a solitary crateriform nodule in sun-exposed areas in elderly, fair-skinned individuals. A KA larger than 20-30 mm is referred to as giant keratoacanthoma, a relatively rare lesion especially in young patients. Such lesions grow rapidly with possible destruction of underlying tissues. In addition to ultraviolet exposure, KAs have also been associated with chemical carcinogens, chemical peels, genetic factors, chronic skin conditions that produce scarring, trauma and thermal burns. Immunosuppressed patients, especially after transplantation, also develop KAs. A viral etiology has been suggested but not confirmed. We encountered a case of giant keratoacanthoma (greater than 50 mm in diameter) with induration of underlying structures on the upper lip of a 39-year-old male sailor. The patient reported sudden appearance and rapid enlargement of the lesion in only three weeks. Biopsy of the cutaneous lesion and the characteristic clinical history suggested the diagnosis of keratoacanthoma. Total excision with primary closure of the defect by a nasolabial advancement flap was performed. Histological examination of the tumor mass confirmed the diagnosis of KA with infiltrative growth and perineural invasion. Immunosuppression was excluded by blood analyses, as were HIV, syphilis and hepatitis infections. Only low-risk genital HPV type 6 was detected in the lesion, suggesting a possible cocarcinogenic effect of HPV and UV light in a chronically sun-exposed patient. PMID:16683389

  18. Small Hydropower in Latvia and Intellectualization of its Operating Systems / Par Mazo HIDROENERĢĒTIKU LATVIJĀ un TĀS Staciju VADĪBAS SISTĒMAS INTELEKTUALIZĀCIJU

    NASA Astrophysics Data System (ADS)

    Mahnitko, A.; Gerhards, J.; Linkevics, O.; Varfolomejeva, R.; Umbrasko, I.

    2013-12-01

    The authors estimate the potential for power generation from water resources of small and medium-sized rivers, which are abundant in Latvia. They propose the algorithm for optimal operation of a small-scale hydropower plant (SHPP) at the chosen optimality criterion in view of the plant's participation in the market. The choice of SHPP optimization algorithm is made based on two mathematical programming methods - dynamic and generalized reduced gradient ones. Approbation of the algorithm is illustrated by an example of optimized SHPP operation. Darbā analizētas tradicionālo un pieejamo vietējo atjaunojamo energoresursu - mazo un vidējo upju hidroresursa izmantošanas iespējas Latvijas enerģētikā. Tiek sniegts faktiskais materiāls šajā jautājumā, kas iegūts, balstoties uz oficiālos avotos publicētiem citu autoru iepriekš veiktajiem pētījumiem. Tiek atzīmēts, ka teritoriju, kas atrodas mazo upju tuvumā un nav ietvertas centralizētās elektroapgādes sistēmā, saimnieciskā apgūšana rada apstākļus patērētāju stimulēšanai izmantot autonomus vietējos energoresursus, ieskaitot hidroenerģiju, izmantojošas mazas jaudas energoiekārtas. Atjaunojamās enerģijas tehnoloģiju un iekārtu pastāvīga attīstība un pilnveidošanās veicinās mazo upju plūsmas izmantošanas elektroenerģijas ražošanas efektivitātes paaugstināšanos. Mūsdienu enerģētikas attīstības koncepcija, kas balstīta uz viedo tīklu (smart grids) izveidi, ļauj paaugstināt mazās hidroenerģētikas darbības efektivitāti, integrējot to elektroenerģētiskajā sistēmā. Mazo hidroelektrostaciju (MHES) darbības vadības sistēmas intelektualizācijas pamatā jābūt kompleksam algoritmam un programmām, kas ļauj tiešsaistes (online) režīmā nodrošināt izdevīgu MHES darbības grafiku (režīmu) maksimālā ienākuma gūšanai, balstoties uz zināmu elektroenerģijas cenas prognozi attiecīgajam laika periodam (diennaktij). MHES darbības optimiz

  19. Calculated Proton Uptake on Anaerobic Reduction of Cytochrome c Oxidase: Is the Reaction Electroneutral?†

    PubMed Central

    Song, Yifan; Michonova-Alexova, Ekaterina; Gunner, M. R.

    2009-01-01

    Cytochrome c oxidase is a transmembrane proton pump that builds an electrochemical gradient using chemical energy from the reduction of O2. Ionization states of all residues were calculated with Multi-Conformation Continuum Electrostatics (MCCE) in seven anaerobic oxidase redox states ranging from fully oxidized to fully reduced. One long-standing problem is how proton uptake is coupled to the reduction of the active site binuclear center (BNC). The BNC has two cofactors: heme a3 and CuB If the protein needs to maintain electroneutrality, then 2 protons will be bound when the BNC is reduced by 2 electrons in the reductive half of the reaction cycle. The effective pKas of ionizable residues around the BNC are evaluated in Rhodobacter sphaeroides cytochrome c oxidase. At pH 7, only a hydroxide coordinated to CuB shifts its pKa from below 7 to above 7 and so picks up a proton when heme a3 and CuB are reduced. Glu I-286, Tyr I-288, His I-334, and a second hydroxide on heme a3 all have pKas above 7 in all redox states, although they have only 1.6–3.5 ΔpK units energy cost for deprotonation. Thus, at equilibrium, they are protonated and cannot serve as proton acceptors. The propionic acids near the BNC are deprotonated with pKas well below 7. They are well stabilized in their anionic state and do not bind a proton upon BNC reduction. This suggests that electroneutrality in the BNC is not maintained during the anaerobic reduction. Proton uptake on reduction of CuA, heme a, heme a3, and CuB shows ≈2.5 protons bound per 4 electrons, in agreement with prior experiments. One proton is bound by a hydroxyl group in the BNC and the rest to groups far from the BNC. The electrochemical midpoint potential (Em) of heme a is calculated in the fully oxidized protein and with 1 or 2 electrons in the BNC. The Em of heme a shifts down when the BNC is reduced, which agrees with prior experiments. If the BNC reduction is electroneutral, then the heme a Em is independent of the BNC

  20. Toward Quantitatively Accurate Calculation of the Redox-Associated Acid-Base and Ligand Binding Equilibria of Aquacobalamin.

    PubMed

    Johnston, Ryne C; Zhou, Jing; Smith, Jeremy C; Parks, Jerry M

    2016-08-01

    Redox processes in complex transition metal-containing species are often intimately associated with changes in ligand protonation states and metal coordination number. A major challenge is therefore to develop consistent computational approaches for computing pH-dependent redox and ligand dissociation properties of organometallic species. Reduction of the Co center in the vitamin B12 derivative aquacobalamin can be accompanied by ligand dissociation, protonation, or both, making these properties difficult to compute accurately. We examine this challenge here by using density functional theory and continuum solvation to compute Co-ligand binding equilibrium constants (Kon/off), pKas, and reduction potentials for models of aquacobalamin in aqueous solution. We consider two models for cobalamin ligand coordination: the first follows the hexa, penta, tetra coordination scheme for Co(III), Co(II), and Co(I) species, respectively, and the second model features saturation of each vacant axial coordination site on Co(II) and Co(I) species with a single, explicit water molecule to maintain six directly interacting ligands or water molecules in each oxidation state. Comparing these two coordination schemes in combination with five dispersion-corrected density functionals, we find that the accuracy of the computed properties is largely independent of the scheme used, but including only a continuum representation of the solvent yields marginally better results than saturating the first solvation shell around Co throughout. PBE performs best, displaying balanced accuracy and superior performance overall, with RMS errors of 80 mV for seven reduction potentials, 2.0 log units for five pKas and 2.3 log units for two log Kon/off values for the aquacobalamin system. Furthermore, we find that the BP86 functional commonly used in corrinoid studies suffers from erratic behavior and inaccurate descriptions of Co-axial ligand binding, leading to substantial errors in predicted pKas and

  1. Toward Quantitatively Accurate Calculation of the Redox-Associated Acid–Base and Ligand Binding Equilibria of Aquacobalamin

    DOE PAGESBeta

    Johnston, Ryne C.; Zhou, Jing; Smith, Jeremy C.; Parks, Jerry M.

    2016-07-08

    In redox processes in complex transition metal-containing species are often intimately associated with changes in ligand protonation states and metal coordination number. Moreover, a major challenge is therefore to develop consistent computational approaches for computing pH-dependent redox and ligand dissociation properties of organometallic species. Reduction of the Co center in the vitamin B12 derivative aquacobalamin can be accompanied by ligand dissociation, protonation, or both, making these properties difficult to compute accurately. We examine this challenge here by using density functional theory and continuum solvation to compute Co ligand binding equilibrium constants (Kon/off), pKas and reduction potentials for models of aquacobalaminmore » in aqueous solution. We consider two models for cobalamin ligand coordination: the first follows the hexa, penta, tetra coordination scheme for CoIII, CoII, and CoI species, respectively, and the second model features saturation of each vacant axial coordination site on CoII and CoI species with a single, explicit water molecule to maintain six directly interacting ligands or water molecules in each oxidation state. Comparing these two coordination schemes in combination with five dispersion-corrected density functionals, we find that the accuracy of the computed properties is largely independent of the scheme used, but including only a continuum representation of the solvent yields marginally better results than saturating the first solvation shell around Co throughout. PBE performs best, displaying balanced accuracy and superior performance overall, with RMS errors of 80 mV for seven reduction potentials, 2.0 log units for five pKas and 2.3 log units for two log Kon/off values for the aquacobalamin system. Furthermore, we find that the BP86 functional commonly used in corrinoid studies suffers from erratic behavior and inaccurate descriptions of Co axial ligand binding, leading to substantial errors in predicted

  2. Digitally Controlled 4-Phase Bi-Directional Interleaved Dc-Dc Converter with Coupled Inductors / Digitāli Vadāms 4 Fāžu Divvirziena Līdzstrāvas Pārveidotājs Ar Saistītajām Droselēm

    NASA Astrophysics Data System (ADS)

    Kroics, K.; Sirmelis, U.; Grigans, L.

    2015-08-01

    The main advantages of multiphase interleaved DC-DC converters over single-phase converters are reduced current stress and reduced output current ripple. Nevertheless, inductor current ripple cannot be reduced only by an interleaving method. The integrated magnetic structure can be used to solve this problem. In this paper, the application of 2-phase coupled inductor designed in a convenient way by using commercially manufactured coil formers and ferrite cores is analysed to develop a 4-phase interleaved DC-DC converter. The steady state phase and output current ripple in a boost mode of the interleaved bidirectional DC-DC converter with integrated magnetics are analysed. The prototype of the converter has been built. The experimental results of the current ripple are presented in the paper. Šajā rakstā piedāvāta magnētiski saistīta drosele, kas izveidota, izmantojot plaša patēriņa ferrīta serdi un tinuma formētāju. Izmantojot šādas droseles, var tikt izveidots vairākfāžu pārveidotājs ar mazām izejas un iejas strāvas pulsācijām, kā arī samazinātām strāvas pulsācijām droselē. Rakstā sīkāk apskatīts līdzstrāvas pārveidotājs, kas sastāv no četrām fāzēm. Šim gadījumam izvestas teorētiskās formulas strāvas pulsāciju aprēķinam, kā arī rakstā parādīti eksperimentālie rezultāti, kas iegūti, testējot prototipu. Teorētiskie rezultāti sakrīt ar eksperimentālajiem

  3. Electrostatic Effects on Proton-Coupled Electron Transfer in Oxomanganese Complexes Inspired by the Oxygen-Evolving Complex of Photosystem II

    PubMed Central

    Amin, Muhamed; Vogt, Leslie; Vassiliev, Serguei; Rivalta, Ivan; Sultan, Mohammad M.; Bruce, Doug; Brudvig, Gary W.; Batista, Victor S.; Gunner, M. R.

    2013-01-01

    The influence of electrostatic interactions on the free energy of proton-coupled-electron-transfer (PCET) in biomimetic oxomanganese complexes inspired by the oxygen-evolving complex (OEC) of photosystem II (PSII), are investigated. The reported study introduces an enhanced Multi-Conformer Continuum Electrostatics (MCCE) model, parameterized at the density functional theory (DFT) level with a classical valence model for the oxomanganese core. The calculated pKas and oxidation midpoint potentials (Ems) match experimental values for eight complexes indicating that purely electrostatic contributions account for most of the observed couplings between deprotonation and oxidation state transitions. We focus on pKas of terminal water ligands in [Mn(II/III)(H2O)6]2+/3+ (1), [Mn(III)(P)(H2O)2]3- (2, P = 5,10,15,20- tetrakis (2,6-dichloro-3-sulfonatophenyl) porphyrinato), [Mn(IV,IV)2(μ-O)2(terpy)2(H2O)2]4+ (3, terpy = 2,2’:6’,2”-terpyridine) and [Mn3(IV,IV,IV)(μ-O)4(phen)4(H2O)2]4+ (4, phen = 1,10-phenanthroline) and the pKas of μ-oxo bridges and Mn Ems in [Mn2(μ-O)2(bpy)4]2+ (5, bpy = 2,2’-bipyridyl), [Mn2(μ-O)2(salpn)2] (6, salpn= N,N′-bis(salicylidene)-1,3-propanediamine), [Mn2(μ-O)2(3,5-di(Cl)-salpn)2] (7) and [Mn2(μ-O)2(3,5-di(NO2)-salpn)2] (8) which are most relevant to PCET mechanisms. The analysis of complexes 6-8 highlights the strong coupling between electron and proton transfers, with any Mn oxidation lowering the pKa of an oxo bridge by 10.5±0.9 pH units. The model also accounts for changes in the Ems due to ligand substituents, such as those in complexes 6-8, due to the electron withdrawing Cl (7) and NO2 (8). The reported study provides the foundation for analysis of electrostatic effects in other oxomanganese complexes and metalloenzymes, where PCET plays a fundamental role in redox-leveling mechanisms. PMID:23570540

  4. γ-Irradiation effects on the non-isothermal decomposition of strontium nitrate by model-free and model-fitting methods

    NASA Astrophysics Data System (ADS)

    Culas, Sunil; Samuel, Jadu

    2013-05-01

    The kinetics of the thermal decomposition of untreated and γ-irradiated strontium nitrate, Sr(NO3)2 was studied under non-isothermal conditions at different heating rates (5, 10, 15 and 20 °C min-1) in nitrogen atmosphere. The data were analysed using both isoconversional and non-isoconversional methods. The activation energies were calculated by Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman (FR) methods. The results show that the irradiation enhances the decomposition and the effect increases with the irradiation dose. The activation energy decreases on irradiation. The appropriate conversion model for the thermal decomposition process selected by means of the master-plot method agrees with three-dimensional diffusion model (D3 mechanism), g(α)=[1-(1-α)1/3]2 for both untreated and irradiated salts at all heating rates.

  5. Keratoacanthoma (KA): An update and review.

    PubMed

    Kwiek, Bartlomiej; Schwartz, Robert A

    2016-06-01

    Keratoacanthoma (KA) is a common but underreported tumor of the skin. Two striking features of KA are its clinical behavior with spontaneous regression after rapid growth and its nosological position on the border between benignity and malignancy. We review current knowledge on the clinical, histopathological, and dermoscopic features of KA to ensure a proper diagnosis and describe its variants, including different types of multiple KAs. We highlight current concepts of KA ethiopathogenesis with special emphasis on the genetic background of multiple familial KA, the role of Wnt signaling pathway, and induction of KA by BRAF inhibitors and procedures of esthetic dermatology. Finally, treatment strategies are presented with surgical excision as a first option, followed by other modalities, including intralesional chemotherapy, topical and systemic agents, lasers, cryotherapy, and photodynamic therapy. PMID:26853179

  6. Harvesting energy from the marine sediment-water interface. III. Kinetic activity of quinone- and antimony-based anode materials

    NASA Astrophysics Data System (ADS)

    Lowy, Daniel A.; Tender, Leonard M.

    Benthic microbial fuel cells (BMFCs) consist of an anode imbedded in marine sediment, connected by an external circuit to a cathode in overlying water. Long-term power density of BMFCs is limited by mass transport of the anode reactants, the transport being attributed to natural processes, including diffusion, convention, and tidal pumping. In order to increase short-term power density of BMFCs and long-term power density of a more recently reported BMFC, which artificially augments mass transport of the anode reactants, new anode materials are reported here with faster kinetics for microbial reduction as compared to commonly used G10 graphite. Results indicate that the kinetic activities (KAs) of glassy carbon graphite with surface-confined anthraquinone-1,6-disulfonic acid (AQDS), graphite paste with an incorporated Sb(V) complex, and oxidized graphite, and oxidized graphite subsequently modified with AQDS is 1.9-218 times greater than the KA of plain G10 graphite.

  7. Current ramp-up with lower hybrid current drive in EAST

    SciTech Connect

    Ding, B. J.; Li, M. H.; Li, J. G.; Kong, E. H.; Zhang, L.; Wei, W.; Li, Y. C.; Wang, M.; Xu, H. D.; Gong, X. Z.; Shen, B.; Liu, F. K.; Shan, J. F.; Fisch, N. J.; Qin, H.; Wilson, J. R.; Collaboration: EAST Team

    2012-12-15

    More economical fusion reactors might be enabled through the cyclic operation of lower hybrid current drive. The first stage of cyclic operation would be to ramp up the plasma current with lower hybrid waves alone in low-density plasma. Such a current ramp-up was carried out successfully on the EAST tokamak. The plasma current was ramped up with a time-averaged rate of 18 kA/s with lower hybrid (LH) power. The average conversion efficiency P{sub el}/P{sub LH} was about 3%. Over a transient phase, faster ramp-up was obtained. These experiments feature a separate measurement of the L/R time at the time of current ramp up.

  8. Proton affinity of the histidine-tryptophan cluster motif from the influenza A virus from ab initio molecular dynamics

    NASA Astrophysics Data System (ADS)

    Bankura, Arindam; Klein, Michael L.; Carnevale, Vincenzo

    2013-08-01

    Ab initio molecular dynamics calculations have been used to compare and contrast the deprotonation reaction of a histidine residue in aqueous solution with the situation arising in a histidine-tryptophan cluster. The latter is used as a model of the proton storage unit present in the pore of the M2 proton conducting ion channel. We compute potentials of mean force for the dissociation of a proton from the Nδ and Nɛ positions of the imidazole group to estimate the pKas. Anticipating our results, we will see that the estimated pKa for the first protonation event of the M2 channel is in good agreement with experimental estimates. Surprisingly, despite the fact that the histidine is partially desolvated in the M2 channel, the affinity for protons is similar to that of a histidine in aqueous solution. Importantly, the electrostatic environment provided by the indoles is responsible for the stabilization of the charged imidazolium.

  9. Pyrolytic and Kinetic Characteristics of the Thermal Decomposition of Perilla frutescens Polysaccharide

    PubMed Central

    Zhou, Quancheng; Sheng, Guihua

    2012-01-01

    The thermal decomposition of Perilla frutescens polysaccharide was examined by thermogravimetry, differential thermogravimetry, and differential thermal analysis. The results showed that the mass loss of the substance proceeded in three steps. The first stage can be attributed to the expulsion of the water from ambient temperature to 182°C. The second stage corresponded to devolatilization from 182°C to 439°C. The residue slowly degraded in the third stage. The weight loss in air is faster than that in nitrogen, because the oxygen in air accelerated the pyrolytic reaction speed reaction. The heating rate significantly affected the pyrolysis of the sample. Similar activation energies of the degradation process (210–211 kJ mol−1) were obtained by the FWO, KAS, and Popescu techniques. According to Popescu mechanism functions, the possible kinetic model was estimated to be Avrami–Erofeev 20 g(α) = [−ln(1–α)]4. PMID:23300715

  10. Thermal stability and decompositions kinetics under non-isothermal conditions of imatinib mesylate α form.

    PubMed

    Mucha, Igor; Baranowski, Przemysław; Owczarek, Artur; Gajda, Maciej; Pluta, Janusz; Górniak, Agata; Niklewicz, Paweł; Karolewicz, Bożena

    2016-09-10

    The thermal decomposition and kinetic parameters of synthetized imatinib mesylate α form α form were determined by thermogravimetry (TGA/DTG) under non-isothermal conditions. The experiments were performed at a 25-940°C temperature range at five different heating rates: 2.5Kmin(-1), 5Kmin(-1), 10Kmin(-1), 15Kmin(-1) and 20Kmin(-1) per minute in a nitrogen atmosphere. Imatinib mesylate α form presents one-step mass loss during the degradation process. The thermal stability of the examined material, the melting temperature (Tonset=220.6°C) and ΔH fusion=-95.74Jg(-1) at a heating rate of 10°Cmin(-1) was established. The values of activation energies have been estimated using Kissinger, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. PMID:27392171

  11. Some features of the technogenic pollution of the Kara Sea, with the example of the sunken nuclear submarine K-27

    NASA Astrophysics Data System (ADS)

    Dmitrievskiy, N. N.; Nikiforov, S. L.; Lobkovsky, L. I.; Ananiev, R. A.

    2015-11-01

    This article discusses the results of offshore operations undertaken during a cruise of the R/V Professor Shtokman (2013) during an expedition in the fjord Stepovoi of the Novaya Zemlya Archipelago k]where the nuclear submarine (NPS) K-27 was scuttled in 1981 k]An echo sounding of her hull showed signs of water destratification k]which may be caused by turbulence from gas or heat flows outgoing from the hull k]According to the hypothesis of the author k]the presence of the reactors and radioactive nuclear fuel remnants may lead to the continued heating of the inner cavities of the submarine and k]as a consequence k]to constant heat flow from its surface k]which is an obvious danger k]including risks associated with plans to refloat and transport the submarine for the further dismantlement.

  12. Bioinspired Molecular Lantern: Tuning the Firefly Oxyluciferin Emission with Host-Guest Chemistry.

    PubMed

    Saleh, Na'il; Suwaid, Abdul Rahman Ba; Alhalabi, Ahmad; Abuibaid, Ahmed Z A; Maltsev, Oleg V; Hintermann, Lukas; Naumov, Panče

    2016-08-11

    Fireflies generate flashes of visible light via luciferase-catalyzed chemiexcitation of the substrate (luciferin) to the first excited state of the emitter (oxyluciferin). Microenvironment effects are often invoked to explain the effects of the luciferase active pocket on the emission; however, the exceedingly complex spectrochemistry and synthetic burdens have precluded elucidation of the nature of these interactions. To decipher the effects of microenvironment on the light emission, here the hydrophobic interior of cucurbit[7]uril (CB7) is used to mimic the nonpolar active pocket of luciferase. The hydrophobic interior of CB7 induces shifts of the ground-state pKas by 1.9-2.5 units to higher values. Upon sequestration, the emission maxima of neutral firefly oxyluciferin and its conjugate monodeprotonated base are blue-shifted by 40 and 39 nm, respectively, resulting in visual color changes of the emitted light. PMID:27442808

  13. Dual fluorescence of naphthylamines in alkaline aqueous solution

    NASA Astrophysics Data System (ADS)

    Ma, Li-Hua; Wen, Zhen-Chang; Lin, Li-Rong; Jiang, Yun-Bao

    2001-10-01

    Dual fluorescence was observed with N-(1-naphthyl)aminoacetate (1-NAA) in aqueous solution of pH 13.0 in the presence of cationic surfactants, cetyltrimethylammonium bromide (CTAB) and chloride (CTAC), below and after the critical micelle concentration (CMC). Similar dual fluorescence was also found with 1- and 2-naphthylamine (1-NA, 2-NA), N-(2-naphthyl)aminoacetate (2-NAA) and (1-naphthyl)ethylenediamine (1-NEDA), in the presence and absence of the cationic surfactants, but not with N, N-disubstituted 1- and 2-NAs. We concluded that the dual fluorescence was due to the excited-state deprotonation of the amino group in these NAs. The p Ka*s of the dual fluorescent NAs were estimated to be around 14 from the dual fluorescence pH titrations. No clear correlation was found for p Ka* with the amino substitution and the presence of cationic micelle.

  14. Thermogravimetric analysis of co-combustion between microalgae and textile dyeing sludge.

    PubMed

    Peng, Xiaowei; Ma, Xiaoqian; Xu, Zhibin

    2015-03-01

    The synergistic interaction and kinetics of microalgae, textile dyeing sludge and their blends were investigated under combustion condition by thermogravimetric analysis. The textile dyeing sludge was blended with microalgae in the range of 10-90wt.% to investigate their co-combustion behavior. Results showed that the synergistic interaction between microalgae and textile dyeing sludge improved the char catalytic effect and alkali metals melt-induced effect on the decomposition of textile dyeing sludge residue at high temperature of 530-800°C. As the heating rate increasing, the entire combustion process was delayed but the combustion intensity was enhanced. The lowest average activation energy was obtained when the percentage of microalgae was 60%, which was 227.1kJ/mol by OFW and 227.4kJ/mol by KAS, respectively. PMID:25618498

  15. Carbonic anhydrase activators: gold nanoparticles coated with derivatized histamine, histidine, and carnosine show enhanced activatory effects on several mammalian isoforms.

    PubMed

    Saada, Mohamed-Chiheb; Montero, Jean-Louis; Vullo, Daniela; Scozzafava, Andrea; Winum, Jean-Yves; Supuran, Claudiu T

    2011-03-10

    Lipoic acid moieties were attached to amine or amino acids showing activating properties against the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1). The obtained lipoic acid conjugates of histamine, L-histidine methyl ester, and L-carnosine methyl ester were attached to gold nanoparticles (NPs) by reaction with Au(III) salts in reducing conditions. The CA activators (CAAs)-coated NPs showed low nanomolar activation (K(A)s of 1-9 nM) of relevant cytosolic, membrane-bound, mitochondrial, and transmembrane CA isoforms, such as CA I, II, IV, VA, VII, and XIV. These NPs also effectively activated CAs ex vivo, in whole blood experiments, with an increase of 200-280% of the CA activity. This is the first example of enzyme activation with nanoparticles and may lead to biomedical applications for conditions in which the CA activity is diminished, such as aging, Alzheimer's disease, or CA deficiency syndrome. PMID:21291238

  16. Induction of Mycobacterium avium proteins upon infection of human macrophages.

    PubMed

    Brunori, Lara; Giannoni, Federico; Bini, Luca; Liberatori, Sabrina; Frota, Cristiane; Jenner, Peter; Thoresen, Ove Fredrik; Orefici, Graziella; Fattorini, Lanfranco

    2004-10-01

    Induction of Mycobacterium avium proteins labelled with [35S]methionine and mRNAs upon infection of the human macrophage cell line THP-1 was investigated by two-dimensional gel electrophoresis-mass spectrometry and reverse transcriptase-polymerase chain reaction (RT-PCR), respectively. M. avium overexpressed proteins within the macrophages that are involved in fatty acids metabolism (FadE2, FixA), cell wall synthesis (KasA), and protein synthesis (EF-tu). The correlation of differential protein and mRNA expression varied between good and no correlation. Overall, these four proteins may be involved in the adaptation and survival of M. avium within human macrophages. PMID:15378697

  17. Studies of the chemical basis of the origin of protein synthesis Initiation and direction of peptide growth

    NASA Technical Reports Server (NTRS)

    Mullins, D. W., Jr.; Lacey, J. C., Jr.

    1980-01-01

    The data presented in this paper show that the ease of nonenzymatic activation of carboxylic acids by ATP at pH 5 varies directly with the pKa of the carboxyl group, and is consistent with the idea that it is the protonated form of the carboxyl group which participates in the activation reaction. Consequently, since most N-blocked amino acids have higher pKas than do their unblocked forms, they are activated more readily, and it has been demonstrated that this principle applies to peptides as well, which are activated more rapidly than single amino acids. It is proposed that this fact may be partly responsible for the origin of two important features still observed in contemporary protein synthesis: (1) initiation in prokaryotes is accomplished with an N-blocked amino acid, and (2) elongation in all living systems occurs at the carboxyl end of the growing peptide.

  18. Geochemical Fate and Transport of Sildenafil and Vardenafil

    NASA Astrophysics Data System (ADS)

    Richter, L.; Boudinot, G.; Vulava, V. M.; Cory, W. C.

    2015-12-01

    The geochemical fate of pharmaceuticals and their degradation products is a developing environmental field. The geologic, chemical, and biological fate of these pollutants has become very relevant with the increase in human population and the resulting increase in pollutant concentrations in the environment. In this study, we focus on sildenafil (SDF) and vardenafil (VDF), active compounds in Viagra and Levitra, respectively, two commonly used erectile dysfunction drugs. The main objective is to determine the sorption potential and transport behavior of these two compounds in natural soils. Both SDF and VDF are complex organic molecules with multiple amine functional groups in their structures. Two types of natural acidic soils (pH≈4.5), an organic-rich soil (7.6% OM) and clay-rich soil (5.1% clay) were used in this study to determine which soil components influence sorption behavior of both compounds. Sorption isotherms measured using batch reactors were nearly linear, but sorption was stronger in soil that contained higher clay content. Both compounds have multiple pKas due to the amine functional groups, the relevant pKas of SDF are 5.97 and 7.27, and those of VDF's are 4.72 and 6.21. These values indicate that these compounds likely behave as cations in soil suspensions and hence were strongly sorbed to negatively-charged clay minerals present in both soils. The clay composition in both soils is predominantly kaolinite with smaller amount of montmorillonite, both of which have a predominantly negative surface charge. Transport experiments using glass chromatography columns indicated that both compounds were more strongly retarded in the clay-rich soils. Breakthrough curves from the transport experiments were modeled using convection-dispersion transport equations. The organic matter in the soil seemed to play a less dominant role in the geochemistry in this study, but is likely to transform both compounds into derivative compounds as seen in other studies.

  19. An Induction Motor Based Wind Turbine Emulator

    NASA Astrophysics Data System (ADS)

    Sokolovs, A.; Grigans, L.; Kamolins, E.; Voitkans, J.

    2014-04-01

    The authors present a small-scale wind turbine emulator based on the AC drive system and discuss the methods for power coefficient calculation. In the work, the experimental set-up consisting of an AC induction motor, a frequency converter, a synchronous permanent magnet generator, a DC-DC boost converter and DC load was simulated and tested using real-life equipment. The experimentally obtained wind turbine power and torque diagrams using the emulator are in a good agreement with the theoretical ones. Šajā rakstā parādīta mazas jaudas vēja turbīnas emulatora izveide ar maiņstrāvas piedziņas sistēmu, kā arī analizētas vairākas turbīnas jaudas koeficienta analītiskās aprēķina metodes. Vēja turbīnas emulatora eksperimentālais stends, kas sastāv no asinhronā elektromotora, frekvenču pārveidotāja, sinhronā pastāvīgo magnētu ģeneratora, līdzstrāvas paaugstinošā pārveidotāja un slodzes, tika pārbaudīts gan simulēšanas vidē, gan uz reālām iekārtām. Eksperimentāli iegūtās vēja turbīnas emulatora jaudas un momenta diagrammas ir salīdzinātas ar teorētiskajām.

  20. A Virtual Mixture Approach to the Study of Multistate Equilibrium: Application to Constant pH Simulation in Explicit Water.

    PubMed

    Wu, Xiongwu; Brooks, Bernard R

    2015-10-01

    Chemical and thermodynamic equilibrium of multiple states is a fundamental phenomenon in biology systems and has been the focus of many experimental and computational studies. This work presents a simulation method to directly study the equilibrium of multiple states. This method constructs a virtual mixture of multiple states (VMMS) to sample the conformational space of all chemical states simultaneously. The VMMS system consists of multiple subsystems, one for each state. The subsystem contains a solute and a solvent environment. The solute molecules in all subsystems share the same conformation but have their own solvent environments. Transition between states is implicated by the change of their molar fractions. Simulation of a VMMS system allows efficient calculation of relative free energies of all states, which in turn determine their equilibrium molar fractions. For systems with a large number of state transition sites, an implicit site approximation is introduced to minimize the cost of simulation. A direct application of the VMMS method is for constant pH simulation to study protonation equilibrium. Applying the VMMS method to a heptapeptide of 3 ionizable residues, we calculated the pKas of those residues both with all explicit states and with implicit sites and obtained consistent results. For mouse epidermal growth factor of 9 ionizable groups, our VMMS simulations with implicit sites produced pKas of all 9 ionizable groups and the results agree qualitatively with NMR measurement. This example demonstrates the VMMS method can be applied to systems of a large number of ionizable groups and the computational cost scales linearly with the number of ionizable groups. For one of the most challenging systems in constant pH calculation, SNase Δ+PHS/V66K, our VMMS simulation shows that it is the state-dependent water penetration that causes the large deviation in lysine66's pKa. PMID:26506245

  1. A Virtual Mixture Approach to the Study of Multistate Equilibrium: Application to Constant pH Simulation in Explicit Water

    PubMed Central

    Wu, Xiongwu; Brooks, Bernard R.

    2015-01-01

    Chemical and thermodynamic equilibrium of multiple states is a fundamental phenomenon in biology systems and has been the focus of many experimental and computational studies. This work presents a simulation method to directly study the equilibrium of multiple states. This method constructs a virtual mixture of multiple states (VMMS) to sample the conformational space of all chemical states simultaneously. The VMMS system consists of multiple subsystems, one for each state. The subsystem contains a solute and a solvent environment. The solute molecules in all subsystems share the same conformation but have their own solvent environments. Transition between states is implicated by the change of their molar fractions. Simulation of a VMMS system allows efficient calculation of relative free energies of all states, which in turn determine their equilibrium molar fractions. For systems with a large number of state transition sites, an implicit site approximation is introduced to minimize the cost of simulation. A direct application of the VMMS method is for constant pH simulation to study protonation equilibrium. Applying the VMMS method to a heptapeptide of 3 ionizable residues, we calculated the pKas of those residues both with all explicit states and with implicit sites and obtained consistent results. For mouse epidermal growth factor of 9 ionizable groups, our VMMS simulations with implicit sites produced pKas of all 9 ionizable groups and the results agree qualitatively with NMR measurement. This example demonstrates the VMMS method can be applied to systems of a large number of ionizable groups and the computational cost scales linearly with the number of ionizable groups. For one of the most challenging systems in constant pH calculation, SNase Δ+PHS/V66K, our VMMS simulation shows that it is the state-dependent water penetration that causes the large deviation in lysine66’s pKa. PMID:26506245

  2. Underlying thermodynamics of pH-dependent allostery.

    PubMed

    Di Russo, Natali V; Martí, Marcelo A; Roitberg, Adrian E

    2014-11-13

    Understanding the effects of coupling protein protonation and conformational states is critical to the development of drugs targeting pH sensors and to the rational engineering of pH switches. In this work, we address this issue by performing a comprehensive study of the pH-regulated switch from the closed to the open conformation in nitrophorin 4 (NP4) that determines its pH-dependent activity. Our calculations show that D30 is the only amino acid that has two significantly different pKas in the open and closed conformations, confirming its critical role in regulating pH-dependent behavior. In addition, we describe the free-energy landscape of the conformational change as a function of pH, obtaining accurate estimations of free-energy barriers and equilibrium constants using different methods. The underlying thermodynamic model of the switch workings suggests the possibility of tuning the observed pKa only through the conformational equilibria, keeping the same conformation-specific pKas, as evidenced by the proposed K125L mutant. Moreover, coupling between the protonation and conformational equilibria results in efficient regulation and pH-sensing around physiological pH values only for some combinations of protonation and conformational equilibrium constants, placing constraints on their possible values and leaving a narrow space for protein molecular evolution. The calculations and analysis presented here are of general applicability and provide a guide as to how more complex systems can be studied, offering insight into how pH-regulated allostery works of great value for designing drugs that target pH sensors and for rational engineering of pH switches beyond the common histidine trigger. PMID:25318010

  3. Is there a role for ketoacid supplements in the management of CKD?

    PubMed

    Shah, Anuja P; Kalantar-Zadeh, Kamyar; Kopple, Joel D

    2015-05-01

    Ketoacid (KA) analogues of essential amino acids (EAAs) provide several potential advantages for people with advanced chronic kidney disease (CKD). Because KAs lack the amino group bound to the α carbon of an amino acid, they can be converted to their respective amino acids without providing additional nitrogen. It has been well established that a diet with 0.3 to 0.4 g of protein per kilogram per day that is supplemented with KAs and EAAs reduces the generation of potentially toxic metabolic products, as well as the burden of potassium, phosphorus, and possibly sodium, while still providing calcium. These KA/EAA-supplemented very-low-protein diets (VLPDs) can maintain good nutrition, but the appropriate dose of the KA/EAA supplement has not been established. Thus, a KA/EAA dose-response study for good nutrition clearly is needed. Similarly, the composition of the KA/EAA supplement needs to be reexamined; for example, some KA/EAA preparations contain neither the EAA phenylalanine nor its analogue. Indications concerning when to inaugurate a KA/EAA-supplemented VLPD therapy also are unclear. Evidence strongly suggests that these diets can delay the need for maintenance dialysis therapy, but whether they slow the loss of glomerular filtration rate in patients with CKD is less clear, particularly in this era of more vigorous blood pressure control and use of angiotensin/aldosterone blockade. Some clinicians prescribe KA/EAA supplements for patients with CKD or treated with maintenance dialysis, but with diets that have much higher protein levels than the VLPDs in which these supplements have been studied. More research is needed to examine the effectiveness of KA/EAA supplements with higher protein intakes. PMID:25682182

  4. Structural elucidation and genomic scrutiny of the C60-C100 mycolic acids of Segniliparus rotundus.

    PubMed

    Lanéelle, Marie-Antoinette; Eynard, Nathalie; Spina, Lucie; Lemassu, Anne; Laval, Françoise; Huc, Emilie; Etienne, Gilles; Marrakchi, Hedia; Daffé, Mamadou

    2013-01-01

    Mycolic acids, very long-chain α-alkyl, β-hydroxylated fatty acids, occur in the members of the order Corynebacteriales where their chain lengths (C(26)-C(88)) and structural features (oxygen functions, cis or trans double bonds, cyclopropane rings and methyl branches) are genus- and species-specific. The molecular composition and structures of the mycolic acids of two species belonging to the genus Segniliparus were determined by a combination of modern analytical chemical techniques, which include MS and NMR. They consist of mono-ethylenic C(62-)C(64) (α'), di-ethylenic C(77)-C(79) (α) and extremely long-chain mycolic acids (α(+)) ranging from 92 to 98 carbon atoms and containing three unsaturations, cis and/or trans double bonds and/or cyclopropanes. The double bonds in each class of mycolic acids were positioned by oxidative cleavage and exhibit locations similar to those of α- and α'-mycolic acids of mycobacteria. For the ultralong chain α-mycolic acids, the three double bonds were located at equally spaced carbon intervals (C(13)-C(16)), with the methyl branches adjacent to the proximal and distal trans double bonds. Examination of the Segniliparus rotundus genome compared with those of other members of the Corynebacteriales indicated two obvious differences in genes encoding the elongation fatty acid (FAS-II) enzymes involved in the biosynthesis of mycolic acids: the organization of 3-ketoacyl-ACP synthases (KasA and KasB) and (3R)-hydroxyacyl-ACP dehydratases (HadAB/BC), on one hand, and the presence of two copies of the hadB gene encoding the catalytic domain of the latter enzyme type, on the other. This observation is discussed in light of the most recent data accumulated on the biosynthesis of this hallmark of Corynebacteriales. PMID:23154972

  5. Protein-protein interactions within the Fatty Acid Synthase-II system of Mycobacterium tuberculosis are essential for mycobacterial viability.

    PubMed

    Veyron-Churlet, Romain; Guerrini, Olivier; Mourey, Lionel; Daffé, Mamadou; Zerbib, Didier

    2004-12-01

    Despite the existence of efficient chemotherapy, tuberculosis remains a leading cause of mortality worldwide. New drugs are urgently needed to reduce the potential impact of the emergence of multidrug-resistant strains of the causative agent Mycobacterium tuberculosis (Mtb). The front-line antibiotic isoniazid (INH), and several other drugs, target the biosynthesis of mycolic acids and especially the Fatty Acid Synthase-II (FAS-II) elongation system. This biosynthetic pathway is essential and specific for mycobacteria and still represents a valuable system for the search of new anti-tuberculous agents. Several data, in the literature, suggest the existence of protein-protein interactions within the FAS-II system. These interactions themselves might serve as targets for a new generation of drugs directed against Mtb. By using an extensive in vivo yeast two-hybrid approach and in vitro co-immunoprecipitation, we have demonstrated the existence of both homotypic and heterotypic interactions between the known components of FAS-II. The condensing enzymes KasA, KasB and mtFabH interact with each other and with the reductases MabA and InhA. Furthermore, we have designed and constructed point mutations of the FAS-II reductase MabA, able to disrupt its homotypic interactions and perturb the interaction pattern of this protein within FAS-II. Finally, we showed by a transdominant genetic approach that these mutants are dominant negative in both non-pathogenic and pathogenic mycobacteria. These data allowed us to draw a dynamic model of the organization of FAS-II. They also represent an important step towards the design of a new generation of anti-tuberculous agents, as being inhibitors of essential protein-protein interactions. PMID:15554959

  6. In situ detection of Mycobacterium tuberculosis transcripts in human lung granulomas reveals differential gene expression in necrotic lesions.

    PubMed

    Fenhalls, Gael; Stevens, Liesel; Moses, Lorraine; Bezuidenhout, Juanita; Betts, Joanna C; Helden Pv, Paul van; Lukey, Pauline T; Duncan, Ken

    2002-11-01

    We have used RNA-RNA in situ hybridization to detect the expression of several Mycobacterium tuberculosis genes in tuberculous granulomas in lung tissue sections from tuberculosis patients. The M. tuberculosis genes chosen fall into two classes. Four genes (icl, narX, and Rv2557 and Rv2558) have been implicated in the persistence of the bacterium in the host, and two genes (iniB and kasA) are upregulated in response to isoniazid exposure. Both necrotic and nonnecrotic granulomas were identified in all of the patients. Necrotic granulomas were divided into three zones: an outer lymphocyte cuff containing lymphocytes and macrophages, a transition zone consisting of necrotic material interspersed with macrophages, and a central acellular necrotic region. Transcripts of all of the genes studied were found in nonnecrotic granulomas and in the lymphocyte cuff of necrotic granulomas. Mycobacterial gene expression was associated with CD68-positive myeloid cells. Rv2557 and/or its homologue Rv2558, kasA, and iniB were expressed within the transition zone of necrotic granulomas, whereas icl and narX transcripts were absent from this area. There was no evidence of transcription of any of the genes examined in the central necrotic region, although mycobacterial DNA was present. The differential expression of genes within granulomas demonstrates that M. tuberculosis exists in a variety of metabolic states and may be indicative of the response to different microenvironments. These observations confirm that genes identified in models of persistence or in response to drug treatment in vitro are expressed in the human host. PMID:12379712

  7. Natural genetic variation in the expression regulation of the chloroplast antioxidant system among Arabidopsis thaliana accessions.

    PubMed

    Juszczak, Ilona; Rudnik, Radoslaw; Pietzenuk, Björn; Baier, Margarete

    2012-09-01

    Photosynthesis is the predominant source of reactive oxygen species in light. In order to prevent the negative influence of reactive oxygen species (ROS) on cell functionality, chloroplasts have evolved a highly efficient antioxidant protection system. Here, we present the first study on natural variation in this system. Comparison of temperature and developmental responses in seven accessions of Arabidopsis thaliana from northern habitats showed that the regulation is widely genetically manifested, but hardly correlates with geographic parameters. Transcript, polysomal RNA (pRNA) and protein data showed that the ecotypes use different strategies to adjust the chloroplast antioxidative defense system, either by regulating transcript abundance or initiation of translation. Comparison of mRNA and pRNA levels showed that Col-0 invests more into transcript accumulation, while Van-0, WS and C24 regulates the chloroplast antioxidant protection system more on the level of pRNA. Nevertheless, both strategies of regulation led to the expression of chloroplast antioxidant enzymes at sufficient level to efficiently protect plants from ROS accumulation in Col-0, WS, C24 and Van-0. On the contrary, Cvi-0, Ms-0 and Kas-1 accumulated high amounts of ROS. The expression of copper/zinc superoxide dismutase (Csd2), ascorbate peroxidases and 2-Cys peroxiredoxins was higher in Cvi-0 on the transcriptional level, while Csd2, peroxiredoxin Q, type II peroxiredoxin E and glutathione peroxidase 1 were induced in Ms-0 on the mRNA level. Similar to Kas-1, in which mRNA levels were less than or similar to Col-0 gene, specific support for translation was observed in Ms-0, showing that the ecotypes use different strategies to adjust the antioxidant system. PMID:22339086

  8. Ni-Al Protective Coating of Steel Electrodes in Dc Electrolysis for Hydrogen Production / Ni-Al Pārklājuma Ietekme Uz Tērauda Elektrodiem Līdzstrāvas Elektrolīzē Ūdeņraža Ražošanai

    NASA Astrophysics Data System (ADS)

    Aizpurietis, P.; Vanags, M.; Kleperis, J.; Bajars, G.

    2013-04-01

    Hydrogen can be a good alternative to fossil fuels under the conditions of world's crisis as an effective energy carrier derived from renewable resources. Among all the known methods of hydrogen production, water electrolysis gives the ecologically purest hydrogen, so it is of importance to maximize the efficiency of this process. The authors consider the influence of plasma sprayed Ni-Al protective coating of 316L steel anode-cathode electrodes in DC electrolysis. In a long-term (24 h) process the anode corrodes strongly, losing Cr and Ni ions which are transferred to the electrolyte, while only minor corrosion of the cathode occurs. At the same time, the composition of anode and cathode electrodes protected by Ni-Al coating changes only slightly during a prolonged electrolysis. As the voltammetry and Tafel plots evidence, the Ni-Al coating protects both the anode and cathode from the corrosion and reduces the potential of hydrogen evolution. The results obtained show that such a coating works best in the case of steel electrodes. Darbā pētīts, kā līdzstrāvas elektrolīzē tērauda 316L elektrodus (anods un katods) ietekmē ar plazmas izputināšanas metodi iegūts Ni-Al pārklājums. Tikko uznestam pārklājumam ir mikrostrukturēta virsma, kas kodināšanas laikā mainās, gan pēc reljefa, gan elementu sastāva. Veicot ilgstošu (24 stundas elektrolīzi), atrasts, ka tikai tērauda elektrods anoda lomā intensīvi korodē un zaudē hroma un niķeļa jonus, kas pāriet elektrolītā, turpretī katods mainās relatīvi maz. Pārklājums Ni-Al pēc uznešanas tiek kodināts karstā sārmā, kad tiek izšķīdināta daļa sastāvā esošo elementu (Al, Si, Cd), bet ilgstošas elektrolīzes laikā pārklājuma sastāvs mainās maz gan anodam, gan katodam. Elektrodu elektroķīmiskie raksturlielumi noteikti ar voltamperometrijas un Tāfeļa līkņu analīzes metodēm. Atrasts, ka Ni-Al pārklājums aizsargā gan anodu, gan katodu no korozijas un samazina

  9. Fused Deposition Modelling as Rapid Prototyping for Structural Material Improvement: Analytical Solution / Ātrās Prototipēšanas Ar Kausēšanas Metodi Strukturālā Uzlabojuma Analītisks Risinājums

    NASA Astrophysics Data System (ADS)

    Brensons, I.; Polukoshko, S.

    2013-10-01

    Fused deposition modelling (FDM) is one of the most effective rapid prototyping (RP) techniques due to its low cost, available materials and versatility. In FDM, a part of material (usually plastic) is made by heating this material to the molten state, and from the melt it is extruded through a nozzle and deposited on a surface. In the article, an alternative RP method is considered for improvement of the mechanical properties of a rapid prototype. The authors propose an analytical solution which allows for achievement of this purpose via advanced technologies. The base materials applied in RP technology can be combined with liquid resin which solidifies after a definite time. This makes it possible to create a channel through the prototype and fill it with another material having better mechanical properties. The optimal channel sizes can be chosen in order to raise the strength of material parts. Darbā tiek apskatīts ātrās prototipēšanas veids, kura pamatā ir detaļas veidošana, izmantojot kausētu materiālu parasti plastmasu. Šī detaļu veidošanas metode ir kļuvusi par vienu no visizplatītākajām tās zemo izmaksu, pieejamo materiālu un daudzpusības dēļ. Šī raksta mērķis ir izpētīt alternatīvu veidu, kā uzlabot prototipu mehāniskās īpašības, tādējādi palielinot printētu detaļu izmantošanu kā gala produktu. Raksts piedāvā analītisku risinājumu, kā uzlabot ātro prototipu mehāniskās īpašības, uzlabojot tehnoloģiskos procesus, kas iesaistīti detaļu izgatavošanā. Darba pamatā tiek izmantota 3D printēšanas tehnoloģijas iespēja veidot iekšējus kanālus bez ģeometriskiem ierobežojumiem, kā rezultātā ir iespējams izveidot iekšēju kanālu shēmu, ko pēc tam piepilda ar citu materiālu, kam ir labākas mehāniskās īpašības kā pamata materiālam. Pildīšanai izmantotais materiāls ir epoksīda sveķi, kas pieļauj vieglu iepildīšanu šķidrā fāzē, un sniedz labas mehāniskās īpašības p

  10. Investigation of daily covering material for biocells

    NASA Astrophysics Data System (ADS)

    Bendere, R.; Smigins, R.; Medne, O.; Berzina-Cimdina, L.; Rugele, K.

    2014-02-01

    Bioreactor landfilling, with the acceptance of landfill Directive 1999/31/EC has lost its actuality in European Union; at the same time, this method can still be used for acceleration of biowaste degradation and biogas production. One of the possibilities to reduce the disposal of biowaste is to use biocells for its anaerobic pre-treatment before landfilling. The daily filling up of such a cell requires isolation of the main volume to limit gas emissions, reduce smells, etc. Bioprocesses that are of the utmost importance for biocell treatment are often not taken into account in selection of materials to be used as daily landfill covers. Based on physical, chemical and biological methods the investigations have been carried out into different covering materials offered in the market, with identification of parameters that are the most important for daily covering the biocells. It is found that the materials fitted best this purpose should be of biological origin and consist of small bio-particles with large surface, without the inhibitors of anaerobic processes such as sulphuric compounds. Bioreaktoru pielietošana atkritumu uzglabāšanas sfērā, sakarā ar Direktīvas 1999/31/EC pieņemšanu, ir zaudējusi savu aktualitāti, taču šī metode vēl joprojām var tikt izmantota bioatkritumu noārdīšanai un biogāzes ražošanai. Viena no iespējām kā samazināt bioatkritumu izvietošanu ir biošūnu izmantošana bioatkritumu anaerobai pirmsapstrādei pirms to noglabāšanas. Šūnas piepildīšana ikdienā prasa nepieciešamību izolēt lielāko tās daļu, lai samazinātu gāzes emisiju, smakas, utt. Materiāli, kas ikdienā tiek izmantoti atkritumu pārklāšanai, nepietiekami ietekmē bioprocesus, kas pamatā ir galvenais biošūnas izmantošanas mērķis. Šajā sakarā ir veikta dažādu tirdzniecībā pieejamu pārklājuma materiālu izpēte, pielietojot virkni fizikālo, ķīmisko un bioloģisko metožu, un nosakot svarīgākos parametrus, kas ir b

  11. Digital Base Band Converter As Radar Vlbi Backend / Dbbc Kā Ciparošanas Sistēma Radara Vlbi Novērojumiem

    NASA Astrophysics Data System (ADS)

    Tuccari, G.; Bezrukovs, Vl.; Nechaeva, M.

    2012-12-01

    can then allow exploring easily the desired range of search for unknown or not fully determined orbit objects. These features make Radar VLBI personality most useful in the space debris measurements. DBBC sistēma izstrādāta Noto Radioastronomijas institūtā. Sistēmas galvenaisuzdevums - palielināt visa Eiropas VLBI tīkla jutību - realizēts, palielinotvisas novērojamās joslas platumu un pielietojot ciparu signālu apstrādes metodes.Izejas datu plūsma palielināta no 1 līdz 4 Gbps katram radioteleskopam un visasoperācijas, kas saistītas ar signālu apstrādi (frekvences pārveidošana, pastiprinājums,iekšējie ģeneratori, utt.), realizētas digitālā formā, kas ļauj iegūt nozīmīgusuzlabojumus atkārtojamībā, precizitātē, vienkāršībā, nemaz neminot vispārzināmāspriekšrocības, ko nodrošina digitālo tehnoloģiju izmantošana. Maksimālā ieejassignāla frekvenču josla ir 3.5 GHz, un momentānais joslas platums ir līdz 1 GHz uzkatru no astoņiem iespējamajiem RF/IF kanāliem. Šī datu reģistrācijas sistēma irļoti veiktspējīga platforma ne tikai EVN, bet arī citiem radioastronomijas pielietojumiem,un papildus tiek izstrādāta vesela virkne programmatūras pakotņu, kasvēl vairāk paplašina sistēmas funkcionalitāti. Tas ietver PFB (Polifāzes FiltruBanka) uztvērējus "Spectra”, kas piemēroti augstas izšķirtspējas spektroskopijasvajadzībām. Papildus realizēts jaunas programmatūras risinājums, ar mērķiizmantot DBBC sistēmu kā daudzfunkcionālu datu ciparošanas iekārtu, kasizmantojama bistatiskiem radara novērojumiem, tai skaitā arī radara VLBInovērojumiem. Šāda veida novērojumos tiek pētīta kosmisko atlūzu populācija,nodrošinot iespēju detektēt pat centimetra

  12. Res-E Support Policies in the Baltic States: Electricity Price Aspect (Part II)

    NASA Astrophysics Data System (ADS)

    Bobinaite, V.; Priedite, I.

    2015-04-01

    Increasing volumes of electricity derived from renewable energy sources (RES-E) affect the electricity market prices and the prices for final electricity consumers in the Baltic States. The results of a multivariate regression analysis show that in 2013 the RES-E contributed to decreasing the electricity market prices in the Baltic States. However, the final electricity consumers pay for the promotion of RES-E through the approved RES-E component which has a tendency to increase. It is estimated that in 2013 the net benefits from the wind electricity promotion were achieved in Lithuania and Latvia while the net cost - in Estonia. This suggests that the economic efficiency of the wind electricity support scheme based on the application of feed-in tariffs was higher than that based on the feed-in premium. Rakstā analizēta elektroenerģijas ražošanas no atjaunojamiem energoresursiem (AER-E) palielināšanas ietekme uz elektroenerģijas tirgus cenu un gala cenu elektroenerģijas lietotājiem Baltijas valstīs. Daudzfaktoru regresijas analīzes rezultāti atklāja, ka AER-E 2013. gadā varētu samazināt elektroenerģijas tirgus cenas Baltijas valstīs. Tomēr jāņem vērā, ka elektroenerģijas lietotāja gala cenā ir iekļauta AER-E atbalsta komponente, kurai ir raksturīgi palielināties. Aprēķināts, ka no vēja elektroenerģijas ražošanas Latvijā un Lietuvā tika iegūta tīrā peļņa, bet Igaunijā tikai nosedza pašizmaksu. Tas liecina, ka vēja elektroenerģijas atbalsta shēmai, kas balstīta uz obligātā iepirkuma atbalsta principu, ir augstāka ekonomiskā efektivitāte, nekā atbalsta shēmai, kas balstīta uz piemaksu par no AER saražoto elektroenerģiju obligātā iepirkuma ietvaros.

  13. Function of heterologous Mycobacterium tuberculosis InhA, a type 2 fatty acid synthase enzyme involved in extending C20 fatty acids to C60-to-C90 mycolic acids, during de novo lipoic acid synthesis in Saccharomyces cerevisiae.

    PubMed

    Gurvitz, Aner; Hiltunen, J Kalervo; Kastaniotis, Alexander J

    2008-08-01

    We describe the physiological function of heterologously expressed Mycobacterium tuberculosis InhA during de novo lipoic acid synthesis in yeast (Saccharomyces cerevisiae) mitochondria. InhA, representing 2-trans-enoyl-acyl carrier protein reductase and the target for the front-line antituberculous drug isoniazid, is involved in the activity of dissociative type 2 fatty acid synthase (FASII) that extends associative type 1 fatty acid synthase (FASI)-derived C(20) fatty acids to form C(60)-to-C(90) mycolic acids. Mycolic acids are major constituents of the protective layer around the pathogen that contribute to virulence and resistance to certain antimicrobials. Unlike FASI, FASII is thought to be incapable of de novo biosynthesis of fatty acids. Here, the genes for InhA (Rv1484) and four similar proteins (Rv0927c, Rv3485c, Rv3530c, and Rv3559c) were expressed in S. cerevisiae etr1Delta cells lacking mitochondrial 2-trans-enoyl-thioester reductase activity. The phenotype of the yeast mutants includes the inability to produce sufficient levels of lipoic acid, form mitochondrial cytochromes, respire, or grow on nonfermentable carbon sources. Yeast etr1Delta cells expressing mitochondrial InhA were able to respire, grow on glycerol, and produce lipoic acid. Commensurate with a role in mitochondrial de novo fatty acid biosynthesis, InhA could accept in vivo much shorter acyl-thioesters (C(4) to C(8)) than was previously thought (>C(12)). Moreover, InhA functioned in the absence of AcpM or protein-protein interactions with its native FASII partners KasA, KasB, FabD, and FabH. None of the four proteins similar to InhA complemented the yeast mutant phenotype. We discuss the implications of our findings with reference to lipoic acid synthesis in M. tuberculosis and the potential use of yeast FASII mutants for investigating the physiological function of drug-targeted pathogen enzymes involved in fatty acid biosynthesis. PMID:18552191

  14. A new genus and family for the misclassified chytrid, Rhizophlyctis harderi.

    PubMed

    Powell, Martha J; Letcher, Peter M; Chambers, James G; Roychoudhury, Sonali

    2015-01-01

    A chytrid first discovered in Mediterranean sands and called Rhizophlyctis harderi was classified in the genus Rhizophlyctis based on its interbiotic vegetative thalli with multiple rhizoidal axes and resting thalli with tufts of rhizoid-like appendages. Developmental, electron microscopic and molecular analyses, however, have brought into question the proper placement of this chytrid. Because its original description was in German and not Latin, the name R. harderi is not validly published. We found that this chytrid produces three thallus forms that could place it in three different morpho-genera: Rhizophydium, Phlyctochytrium or Rhizophlyctis. The ultrastructural architecture of its zoospore is different from that of zoospores of Rhizophlyctis rosea, the type species for Rhizophlyctis, and shares zoospore ultrastructural characteristics with the Rhizophydiales. Zoospores of this chytrid exhibit a distinctive kinetosome-associated structure (KAS), a curved shield bridged to two of the kinetosomal triplets and a layered cap anterior to the kinetosome. Phylogenetic analyses of nuc rDNA also support the placement of this chytrid in the Rhizophydiales and not in the Rhizophlyctidales. Given its molecularly based phylogenetic placement and its distinctive zoospore architecture, we describe this chytrid in a new genus, Uebelmesseromyces, in the Rhizophydiales and erect Uebelmesseromycetaceae as a new family to accommodate it. PMID:25572098

  15. Knowledges and abilities catalog for nuclear power plant operators: Savannah River Site (SRS) production reactors

    SciTech Connect

    Not Available

    1990-06-20

    The Knowledges and Abilities Catalog for Nuclear Power Plant Operations: Savannah River Site (SRS) Production Reactors, provides the basis for the development of content-valid certification examinations for Senior Reactor Operators (SROs) and Central Control Room Supervisors (SUP). The position of Shift Technical Engineer (STE) has been included in the catalog for completeness. This new SRS reactor operating shift crew position is held by an individual holding a CCR Supervisor Certification who has received special engineering and technical training. Also, the STE has a Bachelor of Science degree in engineering or a related technical field. The SRS catalog contains approximately 2500 knowledge and ability (K/A) statements for SROs and SUPs at heavy water moderated production reactors. Each K/A statement has been rated for its importance to the safe operation of the plant in a manner ensuring the health and safety of the public. The SRS K/A catalog is presently organized into five major sections: Plant Systems grouped by Safety Function, Plant Wide Generic K/As, Emergency Plant Evolutions, Theory and Components (to be developed).

  16. Expression Quantitative Trait Locus Mapping across Water Availability Environments Reveals Contrasting Associations with Genomic Features in Arabidopsis[C][W][OPEN

    PubMed Central

    Lowry, David B.; Logan, Tierney L.; Santuari, Luca; Hardtke, Christian S.; Richards, James H.; DeRose-Wilson, Leah J.; McKay, John K.; Sen, Saunak; Juenger, Thomas E.

    2013-01-01

    The regulation of gene expression is crucial for an organism’s development and response to stress, and an understanding of the evolution of gene expression is of fundamental importance to basic and applied biology. To improve this understanding, we conducted expression quantitative trait locus (eQTL) mapping in the Tsu-1 (Tsushima, Japan) × Kas-1 (Kashmir, India) recombinant inbred line population of Arabidopsis thaliana across soil drying treatments. We then used genome resequencing data to evaluate whether genomic features (promoter polymorphism, recombination rate, gene length, and gene density) are associated with genes responding to the environment (E) or with genes with genetic variation (G) in gene expression in the form of eQTLs. We identified thousands of genes that responded to soil drying and hundreds of main-effect eQTLs. However, we identified very few statistically significant eQTLs that interacted with the soil drying treatment (GxE eQTL). Analysis of genome resequencing data revealed associations of several genomic features with G and E genes. In general, E genes had lower promoter diversity and local recombination rates. By contrast, genes with eQTLs (G) had significantly greater promoter diversity and were located in genomic regions with higher recombination. These results suggest that genomic architecture may play an important a role in the evolution of gene expression. PMID:24045022

  17. Exploiting Differential Gene Expression and Epistasis to Discover Candidate Genes for Drought-Associated QTLs in Arabidopsis thaliana

    PubMed Central

    Lovell, John T.; Mullen, Jack L.; Lowry, David B.; Awole, Kedija; Richards, James H.; Sen, Saunak; Verslues, Paul E.; Juenger, Thomas E.; McKay, John K.

    2015-01-01

    Soil water availability represents one of the most important selective agents for plants in nature and the single greatest abiotic determinant of agricultural productivity, yet the genetic bases of drought acclimation responses remain poorly understood. Here, we developed a systems-genetic approach to characterize quantitative trait loci (QTLs), physiological traits and genes that affect responses to soil moisture deficit in the TSUxKAS mapping population of Arabidopsis thaliana. To determine the effects of candidate genes underlying QTLs, we analyzed gene expression as a covariate within the QTL model in an effort to mechanistically link markers, RNA expression, and the phenotype. This strategy produced ranked lists of candidate genes for several drought-associated traits, including water use efficiency, growth, abscisic acid concentration (ABA), and proline concentration. As a proof of concept, we recovered known causal loci for several QTLs. For other traits, including ABA, we identified novel loci not previously associated with drought. Furthermore, we documented natural variation at two key steps in proline metabolism and demonstrated that the mitochondrial genome differentially affects genomic QTLs to influence proline accumulation. These findings demonstrate that linking genome, transcriptome, and phenotype data holds great promise to extend the utility of genetic mapping, even when QTL effects are modest or complex. PMID:25873386

  18. Histidines, heart of the hydrogen ion channel from influenza A virus: Toward an understanding of conductance and proton selectivity

    NASA Astrophysics Data System (ADS)

    Hu, Jun; Fu, Riqiang; Nishimura, Katsuyuki; Zhang, Li; Zhou, Huan-Xiang; Busath, David D.; Vijayvergiya, Viksita; Cross, Timothy A.

    2006-05-01

    The heart of the H+ conductance mechanism in the homotetrameric M2 H+ channel from influenza A is a set of four histidine side chains. Here, we show that protonation of the third of these imidazoles coincides with acid activation of this transmembrane channel and that, at physiological pH, the channel is closed by two imidazole-imidazolium dimers, each sharing a low-barrier hydrogen bond. This unique construct succeeds in distributing a pair of charges over four rings and many atoms in a low dielectric environment to minimize charge repulsion. These dimers form with identical pKas of 8.2 ± 0.2, suggesting cooperative H+ binding and clearly illustrating high H+ affinity for this channel. The protonation behavior of the histidine side chains has been characterized by using solid-state NMR spectroscopy on the M2 transmembrane domain in fully hydrated lipid bilayers where the tetrameric backbone structure is known. Furthermore, electrophysiological measurements of multichannel and single-channel experiments confirm that these protein constructs are functional. M2 channel | proton channel | solid-state NMR | low-barrier hydrogen bond | histidine ionization constants

  19. Synthesis, characterization and non-isothermal decomposition kinetic of a new galactochloralose based polymer.

    PubMed

    Kök, Gökhan; Ay, Kadir; Ay, Emriye; Doğan, Fatih; Kaya, Ismet

    2014-01-30

    A glycopolymer, poly(3-O-methacroyl-5,6-O-isopropylidene-1,2-O-(S)-trichloroethylidene-α-d-galactofuranose) (PMIPTEG) was synthesized from the sugar-carrying methacrylate monomer, 3-O-methacroyl-5,6-O-isopropylidene-1,2-O-(S)-trichloroethylidene-α-d-galactofuranose (MIPTEG) via conventional free radical polymerization with AIBN in 1,4-dioxane. The structures of glycomonomer and their polymers were confirmed by UV-vis, FT-IR, (1)H NMR, (13)C NMR, GPC, TG/DTG-DTA, DSC, and SEM techniques. SEM images showed that PMIPTEG had a straight-chain length structure. On the other hand, the thermal decomposition kinetics of polymer were investigated by means of thermogravimetric analysis in dynamic nitrogen atmosphere at different heating rates. The apparent activation energies for thermal decomposition of the PMIPTEG were calculated using the Kissinger, Kim-Park, Tang, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman methods and were found to be 100.15, 104.40, 102.0, 102.2, 103.2 and 99.6 kJ/mol, respectively. The most likely process mechanism related to the thermal decomposition stage of PMIPTEG was determined to be a Dn deceleration type in terms of master plots results. PMID:24299780

  20. Acid dissociation mechanisms of Si(OH) 4 and Al(H 2O) 63+ in aqueous solution

    NASA Astrophysics Data System (ADS)

    Liu, Xiandong; Lu, Xiancai; Meijer, Evert Jan; Wang, Rucheng; Zhou, Huiqun

    2010-01-01

    Silicic acid and the hexa-aqua of Al 3+ are fundamental model aqueous species of chemical importance in nature. In order to investigate their hydroxyl dissociation mechanisms, Car-Parrinello molecular dynamics (CPMD) simulations were carried out, which allow treating the solutes and solvents on the same footing. The method of constraint was employed to trigger the reactions by taking coordination number as the reaction coordinate and the thermodynamic integration was used to obtain the free-energy profiles. The approximate transition states were located and the reactant and product states were also characterized. The free-energy changes of dissociation are found about 15.0 kcal/mol and 7.7 kcal/mol for silicic acid and Al-aqua, respectively. From the simulation results, the first p Kas were calculated by using two approaches, which are based on the pristine thermodynamic relation and the RDF (radial distribution function)-free energy relation, respectively. Because of more uncertainties involved in the RDF way, it is suggested that the pristine way should be favored, which shows an error margin of 1 p Ka unit. This study provides an encouraging basis for applying the present methodology to predict acidity constants of those groups that are difficult to measure experimentally.

  1. Pyrolytic and kinetic characteristics of Platycodon grandiflorum peel and its cellulose extract.

    PubMed

    Qiu, Hong-Wei; Zhou, Quan-Cheng; Geng, Jie

    2015-03-01

    The pyrolytic and kinetic characteristics of a biomass waste material, namely Platycodon grandiflorum A. DC (P. G.) peel and its cellulose extract were studied at heating rates of 10, 30 and 50 °C/min under a nitrogen flow atmosphere. The most probable mechanism function and activation energy pre-exponential factors were calculated by using the Popescu, FWO and KAS methods. The three stages appeared during pyrolysis include: moisture evaporation, primary devolatilization and residual decomposition. Significant differences in the average activation energy, thermal stability, final residuals and reaction rates of the P. G. peel and its cellulose extract were observed. Stage II of the P. G. peel and its cellulose extract could be described by the function Avrami-Erofeev [-ln(1-α)](3) and the function chemical reaction (1-α)(-0.5), respectively. The average activation energy of P. G. peel and its cellulose extract were 157 and 196 kJ/mol, respectively. Kinetic compensation effects of the pre-exponential factors and activation energy were also observed. PMID:25498683

  2. Influence of affinity on antibody determination in microtiter ELISA systems

    SciTech Connect

    Peterman, J.H.; Voss, E.W. Jr.; Butler, J.E.

    1986-03-01

    Theoretically, all immunoassays are affinity (Ka) dependent when the product of the antibody (Ab) Ka and the free epitope concentration is less than 10. Thus, the degree of dependence on Ka depends on the concentration of available antigen in the system. The authors examined the binding of /sup 125/I-anti-fluorescein (a-FLU) monoclonal antibodies of different affinities to FLU-gelatin adsorbed on Immunlon 2 microtiter plates. Data obtained were in general agreement with our theoretical predictions; the percent of /sup 125/I-a-FLU which bound correlated with Ka, as did the shape of the titration curves. Measurement of 5 a-FLU monoclonals by the ELISA showed that the determination of Ab concentrations depends on the FLU-gelatin concentration, epitope density, and on the relationship between the Kas of test samples and the reference standard Ab preparation. Thus the ELISA is Ka dependent and should not be used routinely to estimate the absolute amount to Ab in unknown samples. However, the Ka dependency of the ELISA might provide a convenient assay for the estimation of the relative functional Ka (rfKa) of antibody preparations.

  3. The Competing Mechanisms of Phosphate Monoester Dianion Hydrolysis

    PubMed Central

    2016-01-01

    Despite the numerous experimental and theoretical studies on phosphate monoester hydrolysis, significant questions remain concerning the mechanistic details of these biologically critical reactions. In the present work we construct a linear free energy relationship for phosphate monoester hydrolysis to explore the effect of modulating leaving group pKa on the competition between solvent- and substrate-assisted pathways for the hydrolysis of these compounds. Through detailed comparative electronic-structure studies of methyl phosphate and a series of substituted aryl phosphate monoesters, we demonstrate that the preferred mechanism is dependent on the nature of the leaving group. For good leaving groups, a strong preference is observed for a more dissociative solvent-assisted pathway. However, the energy difference between the two pathways gradually reduces as the leaving group pKa increases and creates mechanistic ambiguity for reactions involving relatively poor alkoxy leaving groups. Our calculations show that the transition-state structures vary smoothly across the range of pKas studied and that the pathways remain discrete mechanistic alternatives. Therefore, while not impossible, a biological catalyst would have to surmount a significantly higher activation barrier to facilitate a substrate-assisted pathway than for the solvent-assisted pathway when phosphate is bonded to good leaving groups. For poor leaving groups, this intrinsic preference disappears. PMID:27471914

  4. Coupled Electron and Proton Transfer Reactions during the O→E Transition in Bovine Cytochrome c Oxidase

    PubMed Central

    Popović, Dragan M.; Stuchebrukhov, Alexei A.

    2014-01-01

    A combined DFT/electrostatic approach is employed to study the coupling of proton and electron transfer reactions in cytochrome c oxidase (CcO) and its proton pumping mechanism. The coupling of the chemical proton to the internal electron transfer between heme a and the binuclear center is examined for the O→E transition. The novel features of the His291 pumping model are proposed, which involve timely well-synchronized sequence of the proton-coupled electron transfer reactions. The obtained pKas and Ems of the key ionizable and redox-active groups at the different stages of the O→E transition are consistent with available experimental data. The PT step from E242 to H291 is examined in detail for various redox states of the hemes and various conformations of E242 side-chain. Redox potential calculations of the successive steps in the reaction cycle during the O→E transition are able to explain a cascade of equilibria between the different intermediate states and electron redistribution between the metal centers during the course of the catalytic activity. All four electrometric phases are discussed in the light of the obtained results, providing a robust support for the His291 model of proton pumping in CcO. PMID:22086149

  5. PROGRESS IN THE PREDICTION OF pKa VALUES IN PROTEINS

    PubMed Central

    Baker, Nathan; Baptista, Antonio; Huang, Yong; Milletti, Francesca; Nielsen, Jens Erik; Farrell, Damien; Carstensen, Tommy; Olsson, Mats H. M.; Shen, Jana K.; Warwicker, Jim; Williams, Sarah; Word, J. Michael

    2011-01-01

    The pKa-cooperative aims to provide a forum for experimental and theoretical researchers interested in protein pKa values and protein electrostatics in general. The first round of the pKa-cooperative, which challenged computational labs to carry out blind predictions against pKas experimentally determined in the laboratory of Bertrand Garcia-Moreno, was completed and results discussed at the Telluride meeting (July 6–10, 2009). This paper serves as an introduction to the reports submitted by the blind prediction participants that will be published in a special issue of PROTEINS: Structure, Function and Bioinformatics. Here we briefly outline existing approaches for pKa calculations, emphasizing methods that were used by the participants in calculating the blind pKa values in the first round of the cooperative. We then point out some of the difficulties encountered by the participating groups in making their blind predictions, and finally try to provide some insights for future developments aimed at improving the accuracy of pKa calculations. PMID:22002859

  6. Comparative study on pyrolysis of lignocellulosic and algal biomass using a thermogravimetric and a fixed-bed reactor.

    PubMed

    Yuan, Ting; Tahmasebi, Arash; Yu, Jianglong

    2015-01-01

    Pyrolysis characteristics of four algal and lignocellulosic biomass samples were studied by using a thermogravimetric analyzer (TGA) and a fixed-bed reactor. The effects of pyrolysis temperature and biomass type on the yield and composition of pyrolysis products were investigated. The average activation energy for pyrolysis of biomass samples by FWO and KAS methods in this study were in the range of 211.09-291.19kJ/mol. CO2 was the main gas component in the early stage of pyrolysis, whereas H2 and CH4 concentrations increased with increasing pyrolysis temperature. Bio-oil from Chlorellavulgaris showed higher content of nitrogen containing compounds compared to lignocellulosic biomass. The concentration of aromatic organic compounds such as phenol and its derivatives were increased with increasing pyrolysis temperature up to 700°C. FTIR analysis results showed that with increasing pyrolysis temperature, the concentration of OH, CH, CO, OCH3, and CO functional groups in char decreased sharply. PMID:25459840

  7. Histidines, heart of the hydrogen ion channel from influenza A virus: Toward an understanding of conductance and proton selectivity

    PubMed Central

    Hu, Jun; Fu, Riqiang; Nishimura, Katsuyuki; Zhang, Li; Zhou, Huan-Xiang; Busath, David D.; Vijayvergiya, Viksita; Cross, Timothy A.

    2006-01-01

    The heart of the H+ conductance mechanism in the homotetrameric M2 H+ channel from influenza A is a set of four histidine side chains. Here, we show that protonation of the third of these imidazoles coincides with acid activation of this transmembrane channel and that, at physiological pH, the channel is closed by two imidazole–imidazolium dimers, each sharing a low-barrier hydrogen bond. This unique construct succeeds in distributing a pair of charges over four rings and many atoms in a low dielectric environment to minimize charge repulsion. These dimers form with identical pKas of 8.2 ± 0.2, suggesting cooperative H+ binding and clearly illustrating high H+ affinity for this channel. The protonation behavior of the histidine side chains has been characterized by using solid-state NMR spectroscopy on the M2 transmembrane domain in fully hydrated lipid bilayers where the tetrameric backbone structure is known. Furthermore, electrophysiological measurements of multichannel and single-channel experiments confirm that these protein constructs are functional. PMID:16632600

  8. Behavioral pathways explaining oral health disparity in children.

    PubMed

    Gao, X-L; Hsu, C-Y S; Xu, Y C; Loh, T; Koh, D; Hwarng, H B

    2010-09-01

    Policymakers' understanding of and ability to reduce health disparities are pivotal for health promotion worldwide. This study aimed to verify the behavioral pathways leading to oral health disparities. Oral examinations were conducted for 1782 randomly selected preschoolers (3-6 yrs), and 1576 (88.4%) participants were followed up after 12 months. Parents were surveyed on their knowledge (K), attitude (A), and practices (P) regarding their children's oral health homecare (infant feeding, diet, and oral hygiene) and dental attendance. Structural equation modeling substantiated the links between specific KAs and corresponding practices, while generic KA did not affect practices. KAP pathways partly explained the ethnic and socio-economic disparities in oral health. Deprivation had a direct effect (not mediated by KA) on dental attendance, but not on oral health homecare. Ethnicity directly influenced oral health homecare practices, but not dental attendance. These behavioral pathways, furthering our understanding of health disparity, may have practical implications for health promotion and policy-making. PMID:20554887

  9. COMPASS Final Report: Lunar Communications Terminal (LCT)

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; McGuire, Melissa L.

    2010-01-01

    The Lunar Communications Terminal (LCT) COllaborative Modeling and Parametric Assessment of Space Systems (COMPASS) session designed a terminal to provide communications between lunar South Pole assets, communications relay to/from these assets through an orbiting Lunar Relay Satellite (LRS) and navigation support. The design included a complete master equipment list, power requirement list, configuration design, and brief risk assessment and cost analysis. The Terminal consists of a pallet containing the communications and avionics equipment, surrounded by the thermal control system (radiator), an attached, deployable 10-m tower, upon which were mounted locally broadcasting and receiving modems and a deployable 1 m diameter Ka/S band dish which provides relay communications with the lunar relay satellites and, as a backup, Earth when it is in view. All power was assumed to come from the lunar outpost Habitat. Three LCT design options were explored: a stand-alone LCT servicing the manned outpost, an integrated LCT (into the Habitat or Lunar Lander), and a mini-LCT which provides a reduced level of communication for primarily robotic areas dealing as in situ resource utilization (ISRU) and remote science. Where possible all the designs assumed single fault tolerance. Significant mass savings were found when integrating the LCT into the Habitat or Lander but increases in costs occurred depending upon the level of man rating required for such designs.

  10. Socio-demographic and Health Behavioral Correlates of Depressive Symptoms among Korean Americans

    PubMed Central

    Cho, Sunhee; Park, So-Young; Bernstein, Kunsook S; Roh, Soonhee; Jeon, Gyeong-Suk

    2015-01-01

    This study identified socio-demographic characteristics and their help seeking behaviors of depressive symptoms among adult Korean Americans (KAs). Using survey data from 230 residents of the New York City, Teaneck New Jersey, and Philadelphia areas, simple and multiple logistic regression analyses were performed to assess the association between depressive symptoms and the covariates. Women were at much lower risk of depressive symptoms than were men, even after adjusting other covariates (OR=0.45, 95% CI=0.21–0.96). Having no health insurance(OR=4.02, 95% CI=1.28–12.61) and having experience in seeking professional help for mental health problem during last year were significantly associated with depressive symptoms (OR=2.96, 95% CI=1.29–6.80). Impact of gender, lack of health insurance coverage, and previous help-seeking behavior may be possible explanations for the KA’s higher prevalence of depression. PMID:25536937

  11. Genome scale transcriptional response diversity among ten ecotypes of Arabidopsis thaliana during heat stress

    PubMed Central

    Barah, Pankaj; Jayavelu, Naresh D.; Mundy, John; Bones, Atle M.

    2013-01-01

    In the scenario of global warming and climate change, heat stress is a serious threat to crop production worldwide. Being sessile, plants cannot escape from heat. Plants have developed various adaptive mechanisms to survive heat stress. Several studies have focused on diversity of heat tolerance levels in divergent Arabidopsis thaliana (A. thaliana) ecotypes, but comprehensive genome scale understanding of heat stress response in plants is still lacking. Here we report the genome scale transcript responses to heat stress of 10 A. thaliana ecotypes (Col, Ler, C24, Cvi, Kas1, An1, Sha, Kyo2, Eri, and Kond) originated from different geographical locations. During the experiment, A. thaliana plants were subjected to heat stress (38°C) and transcript responses were monitored using Arabidopsis NimbleGen ATH6 microarrays. The responses of A. thaliana ecotypes exhibited considerable variation in the transcript abundance levels. In total, 3644 transcripts were significantly heat regulated (p < 0.01) in the 10 ecotypes, including 244 transcription factors and 203 transposable elements. By employing a systems genetics approach- Network Component Analysis (NCA), we have constructed an in silico transcript regulatory network model for 35 heat responsive transcription factors during cellular responses to heat stress in A. thaliana. The computed activities of the 35 transcription factors showed ecotype specific responses to the heat treatment. PMID:24409190

  12. Greenhouse Gas Emission Reduction Due to Improvement of Biodegradable Waste Management System

    NASA Astrophysics Data System (ADS)

    Bendere, R.; Teibe, I.; Arina, D.; Lapsa, J.

    2014-12-01

    ārdāmo atkritumu apsaimniekošanas statistikas datu novērtējums atbilstoši likumdošanas prasībām. Izmantojot matemātisko modelēšanas programmu WAMPS, analizēti trīs dažādi bioloģisko noārdāmo atkritumu apsaimniekošanas scenāriji, kuriem veikts vides ietekmes novērtējums, kas izteikts klimata pārmaiņu potenciālā - tonnas CO2 ekv. Darbā secināts, ka lielākais siltumnīcefektu (SEG) avots atkritumu apsaimniekošanas ir atkritumu poligoni (Bāzes scenārijs), ko galvenokārt ietekmē CH4 rašanās, organiskajiem atkritumiem sadaloties anaerobos apstākļos. Būtisku pozitīvo efektu SEG emisiju samazināšanā dod atkritumu pārstrāde otrreizējās izejvielās un sadedzināšana cementa ražotnē, kas ļauj samazināt dabīgo izejmateriālu un fosilo enerģijas resursu patēriņu. Attīstot pārtikas atkritumu pārstrādi biogāzē, lietderīgi veidot alternatīvās vai izmantot esošās sistēmas, kas nodrošina iegūtās enerģijas un digestāta patēriņu, t.i lauksaimniecība, transports vai komunālie pakalpojumi. Lai no zaļajiem dārza atkritumiem iegūtu augstvērtīgu kompostu, valstī jārada tam nepieciešami likumdošanas un ekonomiskie instrumenti, kas veicina komposta tirgus attīstību.

  13. Endosomal escape and siRNA delivery with cationic shell crosslinked knedel-like nanoparticles with tunable buffering capacities

    PubMed Central

    Shrestha, Ritu; Elsabahy, Mahmoud; Florez-Malaver, Stephanie; Samarajeewa, Sandani; Wooley, Karen L.

    2012-01-01

    Cationic shell crosslinked knedel-like nanoparticles (cSCKs) have emerged as a highly efficient transfection agent for nucleic acids delivery. In this study, a new class of cSCKs with tunable buffering capacities has been developed by altering the amounts of histamines and primary amines incorporated into their crosslinked shell regions. The effect of histamine content of these nanoparticles with a hydrodynamic diameter of ca. 20 nm, on the siRNA-binding affinity, cytotoxicity, immunogenicity, and transfection efficiency was investigated. The modification of cSCKs with histamine was found to reduce the siRNA-binding affinity and cellular binding. On the other hand, it significantly reduced the toxicity and immunogenicity of the nanoparticles with subsequent increase in the transfection efficiency. In addition, escape from endosomes was facilitated by having two species of low and high pKas (i.e. histamine and primary amine groups, respectively), as demonstrated by the potentiometric titration experiments and the effect of bafilomycin A1, an inhibitor of the endosomal acidification, on the transfection efficiency of cSCKs. Histamine modification of 15 mol% was a threshold, above which cSCKs with higher histamine content completely lost the ability to bind siRNA and to transfect cells. This study highlights the potential of histamine incorporation to augment the gene silencing activity of cationic nanoparticles, reduce their toxicity, and increase their biocompatibility, which is of particular importance in the design of nucleic acids delivery vectors. PMID:22901966

  14. Comprehensive examination of dopants and defects in BaTiO3 from first principles

    NASA Astrophysics Data System (ADS)

    Sharma, V.; Pilania, G.; Rossetti, G. A., Jr.; Slenes, K.; Ramprasad, R.

    2013-04-01

    An extensive assessment of the physicochemical factors that control the behavior of dopant-related defects in BaTiO3 has been performed using high-throughput first-principles computations. Dopants spanning the Periodic Table—44 in total—including K-As, Rb-Sb, and Cs-Bi were considered, and have allowed us to reveal previously unknown correlations, chemical trends, and the interplay between stability, chemistry, and electrical activity. We quantitatively show that the most important factor that determines dopant stability in BaTiO3 is the dopant ionic size (followed by its oxidation state). Moreover, we are also able to identify definitively dopants that are O vacancy formers and suppressors, and those that would lead to p-type versus n-type conduction. Our results are in agreement with available experimental data (with no violations thus far), and point to an attractive computational route to dopant selection in BaTiO3 as well as in other materials.

  15. Development of a Synthetic Oxytetracycline-Inducible Expression System for Streptomycetes Using de Novo Characterized Genetic Parts.

    PubMed

    Wang, Weishan; Yang, Tongjian; Li, Yihong; Li, Shanshan; Yin, Shouliang; Styles, Kathryn; Corre, Christophe; Yang, Keqian

    2016-07-15

    Precise control of gene expression using exogenous factors is of great significance. To develop ideal inducible expression systems for streptomycetes, new genetic parts, oxytetracycline responsive repressor OtrR, operator otrO, and promoter otrBp from Streptomyces rimosus, were selected de novo and characterized in vivo and in vitro. OtrR showed strong affinity to otrO (KD = 1.7 × 10(-10) M) and oxytetracycline induced dissociation of the OtrR/DNA complex in a concentration-dependent manner. On the basis of these genetic parts, a synthetic inducible expression system Potr* was optimized. Induction of Potr* with 0.01-4 μM of oxytetracycline triggered a wide-range expression level of gfp reporter gene in different Streptomyces species. Benchmarking Potr* against the widely used constitutive promoters ermE* and kasOp* revealed greatly enhanced levels of expression when Potr* was fully induced. Finally, Potr* was used as a tool to activate and optimize the expression of the silent jadomycin biosynthetic gene cluster in Streptomyces venezuelae. Altogether, the synthetic Potr* presents a new versatile tool for fine-tuning gene expression in streptomycetes. PMID:27100123

  16. Kinetics of co-pyrolysis of sawdust, coal and tar.

    PubMed

    Montiano, M G; Díaz-Faes, E; Barriocanal, C

    2016-04-01

    Two coals, sawdust and coal tar were selected to prepare briquettes. Thermogravimetric analyses at three heating rates (i.e. 10, 20 and 30°C/min) and up to 1000°C were carried out with the briquette components. Four blends were prepared and the experimental decomposition profiles were compared with the calculated data taking into account the amount of each component in the blend. No interaction was found when comparing the experimental and calculated decomposition profiles of the blends. Isoconversional models OFW (Ozawa-Flynn-Wall) and KAS (Kissinger-Akahira-Sunose) were used to obtain the activation energies of the blend components. The activation energies obtained were introduced in the Coats-Redfern (CR) model to derive the pre-exponential factors. The thermal decomposition profiles calculated using the kinetic parameters were in good agreement with the experimental results in the case of the briquette components, but worse results were obtained in the case of the blends due to their greater complexity. PMID:26829530

  17. Calculating Free Energy Changes in Continuum Solvation Models.

    PubMed

    Ho, Junming; Ertem, Mehmed Z

    2016-02-25

    We recently showed for a large data set of pKas and reduction potentials that free energies calculated directly within the SMD continuum model compares very well with corresponding thermodynamic cycle calculations in both aqueous and organic solvents [ Phys. Chem. Chem. Phys. 2015 , 17 , 2859 ]. In this paper, we significantly expand the scope of our study to examine the suitability of this approach for calculating general solution phase kinetics and thermodynamics, in conjunction with several commonly used solvation models (SMD-M062X, SMD-HF, CPCM-UAKS, and CPCM-UAHF) for a broad range of systems. This includes cluster-continuum schemes for pKa calculations as well as various neutral, radical, and ionic reactions such as enolization, cycloaddition, hydrogen and chlorine atom transfer, and SN2 and E2 reactions. On the basis of this benchmarking study, we conclude that the accuracies of both approaches are generally very similar-the mean errors for Gibbs free energy changes of neutral and ionic reactions are approximately 5 and 25 kJ mol(-1), respectively. In systems where there are significant structural changes due to solvation, as is the case for certain ionic transition states and amino acids, the direct approach generally afford free energy changes that are in better agreement with experiment. PMID:26878566

  18. Structure-Activity Relationships for Rates of Aromatic Amine Oxidation by Manganese Dioxide.

    PubMed

    Salter-Blanc, Alexandra J; Bylaska, Eric J; Lyon, Molly A; Ness, Stuart C; Tratnyek, Paul G

    2016-05-17

    New energetic compounds are designed to minimize their potential environmental impacts, which includes their transformation and the fate and effects of their transformation products. The nitro groups of energetic compounds are readily reduced to amines, and the resulting aromatic amines are subject to oxidation and coupling reactions. Manganese dioxide (MnO2) is a common environmental oxidant and model system for kinetic studies of aromatic amine oxidation. In this study, a training set of new and previously reported kinetic data for the oxidation of model and energetic-derived aromatic amines was assembled and subjected to correlation analysis against descriptor variables that ranged from general purpose [Hammett σ constants (σ(-)), pKas of the amines, and energies of the highest occupied molecular orbital (EHOMO)] to specific for the likely rate-limiting step [one-electron oxidation potentials (Eox)]. The selection of calculated descriptors (pKa, EHOMO, and Eox) was based on validation with experimental data. All of the correlations gave satisfactory quantitative structure-activity relationships (QSARs), but they improved with the specificity of the descriptor. The scope of correlation analysis was extended beyond MnO2 to include literature data on aromatic amine oxidation by other environmentally relevant oxidants (ozone, chlorine dioxide, and phosphate and carbonate radicals) by correlating relative rate constants (normalized to 4-chloroaniline) to EHOMO (calculated with a modest level of theory). PMID:27074054

  19. The PLP cofactor: Lessons from studies on model reactions

    PubMed Central

    Richard, John P.; Amyes, Tina L.; Crugeiras, Juan; Rios, Ana

    2012-01-01

    Experimental probes of the acidity of weak carbon acids have been developed and used to determine the carbon acid pKas of glycine, glycine derivatives and iminium ion adducts of glycine to the carbonyl group, including 5′-deoxypyridoxal (DPL). The high reactivity of the DPL-stabilized glycyl carbanion towards nucleophilic addition to both DPL and the glycine-DPL iminium ion favors the formation of Claisen condensation products at enzyme active sites. The formation of the iminium ion between glycine and DPL is accompanied by a 12-unit decrease in the pKa of 29 for glycine. The complicated effects of formation of glycine iminium ions to DPL and other aromatic and aliphatic aldehydes and ketones on carbon acid pKa are discussed. These data provide insight into the contribution of the individual pyridine ring substituents to the catalytic efficiency of DPL It is suggested that the 5′-phosphodianion group of PLP may play an important role in enzymatic catalysis of carbon deprotonation by providing up to 12 kcal/mol of binding energy that is utilized to stabilize the transition state for the enzymatic reaction. PMID:21182991

  20. Blockade of interleukin-6 signalling with siltuximab enhances melphalan cytotoxicity in preclinical models of multiple myeloma.

    PubMed

    Hunsucker, Sally A; Magarotto, Valeria; Kuhn, Deborah J; Kornblau, Steven M; Wang, Michael; Weber, Donna M; Thomas, Sheeba K; Shah, Jatin J; Voorhees, Peter M; Xie, Hong; Cornfeld, Mark; Nemeth, Jeffrey A; Orlowski, Robert Z

    2011-03-01

    Signalling through the interleukin (IL)-6 pathway induces proliferation and drug resistance of multiple myeloma cells. We therefore sought to determine whether the IL-6-neutralizing monoclonal antibody siltuximab, formerly CNTO 328, could enhance the activity of melphalan, and to examine some of the mechanisms underlying this interaction. Siltuximab increased the cytotoxicity of melphalan in KAS-6/1, INA-6, ANBL-6, and RPMI 8226 human myeloma cell lines (HMCLs) in an additive-to-synergistic manner, and sensitized resistant RPMI 8226.LR5 cells to melphalan. These anti-proliferative effects were accompanied by enhanced activation of drug-specific apoptosis in HMCLs grown in suspension, and in HMCLs co-cultured with a human-derived stromal cell line. Siltuximab with melphalan enhanced activation of caspase-8, caspase-9, and the downstream effector caspase-3 compared with either of the single agents. This increased induction of cell death occurred in association with enhanced Bak activation. Neutralization of IL-6 also suppressed signalling through the phosphoinositide 3-kinase/Akt pathway, as evidenced by decreased phosphorylation of Akt, p70 S6 kinase and 4E-BP1. Importantly, the siltuximab/melphalan regimen demonstrated enhanced anti-proliferative effects against primary plasma cells derived from patients with myeloma, monoclonal gammopathy of undetermined significance, and amyloidosis. These studies provide a rationale for translation of siltuximab into the clinic in combination with melphalan-based therapies. PMID:21241278

  1. M. tuberculosis intramembrane protease Rip1 controls transcription through three anti-sigma factor substrates.

    PubMed

    Sklar, Joseph G; Makinoshima, Hideki; Schneider, Jessica S; Glickman, Michael S

    2010-08-01

    Regulated intramembrane proteolysis (RIP) is a mechanism of transmembrane signal transduction that functions through intramembrane proteolysis of substrates. We previously reported that the RIP metalloprotease Rv2869c (Rip1) is a determinant of Mycobacterium tuberculosis (Mtb) cell envelope composition and virulence, but the substrates of Rip1 were undefined. Here we show that Rip1 cleaves three transmembrane anti-sigma factors: anti-SigK, anti-SigL and anti-SigM, negative regulators of Sigma K, L and M. We show that transcriptional activation of katG in response to phenanthroline requires activation of SigK and SigL by Rip1 cleavage of anti-SigK and anti-SigL. We also demonstrate a Rip1-dependent pathway that activates the genes for the mycolic acid biosynthetic enzyme KasA and the resuscitation promoting factor RpfC, but represses the bacterioferritin encoding gene bfrB. Regulation of these three genes by Rip1 is not reproduced by deletion of Sigma K, L or M, either indicating a requirement for multiple Rip1 substrates or additional arms of the Rip1 pathway. These results identify a branched proteolytic signal transduction system in which a single intramembrane protease cleaves three anti-sigma factor substrates to control multiple downstream pathways involved in lipid biosynthesis and defence against oxidative stress. PMID:20545848

  2. Modeling bacterial evolution with comparative-genome-based marker systems: application to Mycobacterium tuberculosis evolution and pathogenesis.

    PubMed

    Alland, David; Whittam, Thomas S; Murray, Megan B; Cave, M Donald; Hazbon, Manzour H; Dix, Kim; Kokoris, Mark; Duesterhoeft, Andreas; Eisen, Jonathan A; Fraser, Claire M; Fleischmann, Robert D

    2003-06-01

    The comparative-genomic sequencing of two Mycobacterium tuberculosis strains enabled us to identify single nucleotide polymorphism (SNP) markers for studies of evolution, pathogenesis, and epidemiology in clinical M. tuberculosis. Phylogenetic analysis using these "comparative-genome markers" (CGMs) produced a highly unusual phylogeny with a complete absence of secondary branches. To investigate CGM-based phylogenies, we devised computer models to simulate sequence evolution and calculate new phylogenies based on an SNP format. We found that CGMs represent a distinct class of phylogenetic markers that depend critically on the genetic distances between compared "reference strains." Properly distanced reference strains generate CGMs that accurately depict evolutionary relationships, distorted only by branch collapse. Improperly distanced reference strains generate CGMs that distort and reroot outgroups. Applying this understanding to the CGM-based phylogeny of M. tuberculosis, we found evidence to suggest that this species is highly clonal without detectable lateral gene exchange. We noted indications of evolutionary bottlenecks, including one at the level of the PHRI "C" strain previously associated with particular virulence characteristics. Our evidence also suggests that loss of IS6110 to fewer than seven elements per genome is uncommon. Finally, we present population-based evidence that KasA, an important component of mycolic acid biosynthesis, develops G312S polymorphisms under selective pressure. PMID:12754238

  3. Insights into the distribution and functions of the eukaryotic GPI-like anchored genes among Mycobacterium from a comparative genomic perspective.

    PubMed

    Deng, Wanyan; Zeng, Jie; Xiang, Xiaohong; Xie, Jianping

    2012-01-01

    Glycosylphosphatidylinositol (GPI)-anchored proteins range from small peptides to larger antigens and fulfill a variety of cellular functions in eukaryotes. We speculated there should be such molecules in intracellular pathogens such as Mycobacterium due to their complex interplay with the host. However, no prior publications have touched this topic. To explore the existence and distribution of GPI-like molecules among Mycobacterium, we exhaustively analyzed all publicly available Mycobacterium genomes and found that the GPI-like signal sequences are prevalent among Mycobacterium, and a significant dichotomy between nonpathogenic Mycobacterium (exemplified by Mycobacterium smegmatis) and pathogenic Mycobacterium (exemplified by Mycobacterium tuberculosis), through genome-wide GPI-SOM analysis. Some well-documented anti-tuberculosis drug targets are predicted to have GPI-like anchored signals, such as KasA and atpE. Interestingly, Pro-Glu (PE) and Pro-Pro-Glu (PPE) proteins predicted to have GPI-anchoring sequence are unique to pathogenic Mycobacterium. These results can be further explored for better control measures against tuberculosis. PMID:23272800

  4. Detection of mutations associated with isoniazid resistance in Mycobacterium tuberculosis isolates from China.

    PubMed

    Zhang, Min; Yue, Jun; Yang, Yan-Ping; Zhang, Hong-Mei; Lei, Jian-Qiang; Jin, Rui-Liang; Zhang, Xue-Lian; Wang, Hong-Hai

    2005-11-01

    Nine structural genes (furA, katG, inhA, kasA, Rv0340, iniB, iniA, iniC, and efpA) and two regulatory regions (the oxyR-ahpC intergenic region and the promoter of mabA-inhA) in 87 isoniazid (INH)-monoresistant and 50 INH-susceptible Mycobacterium tuberculosis isolates collected from five provinces of China were analyzed by sequencing. Eighty-two (94.3%) INH-resistant isolates had mutations in the katG gene, with the katG Ser315Thr mutation predominant (55.2%). No mutation at codon 463 of katG was detected among the 50 INH-susceptible isolates with different IS6110 fingerprints. In addition, there were 35 (40.2%) INH-resistant isolates that had a mutation at codon 463 of katG. Of the INH-resistant strains, 20 (23.0%) isolates harbored double mutations at two separate loci of katG. Mutations in the inhA promoter region occurred in 13 (14.9%) isolates; 4.6% of the isolates had inhA structural gene mutations, and 11.5% harbored mutations in the oxyR-ahpC intergenic region. Drug resistance-associated mutations were detected in the iniBAC region and efpA. PMID:16272473

  5. Progress in the prediction of pKa values in proteins

    SciTech Connect

    Alexov, Emil; Mehler, Ernest L.; Baker, Nathan A.; Baptista, Antonio; Huang, Yong; Milletti, Francesca; Nielsen, Jens E.; Farrell, Damien; Carstensen, Tommy; Olsson, Mats H.; Shen, Jana K.; Warwicker, Jim; Williams, Sarah; Word, J Michael

    2011-12-15

    The pKa-cooperative aims to provide a forum for experimental and theoretical researchers interested in protein pKa values and protein electrostatics in general. The first round of the pKa -cooperative, which challenged computational labs to carry out blind predictions against pKas experimentally determined in the laboratory of Bertrand Garcia-Moreno, was completed and results discussed at the Telluride meeting (July 6-10, 2009). This paper serves as an introduction to the reports submitted by the blind prediction participants that will be published in a special issue of PROTEINS: Structure, Function and Bioinformatics. Here we briefly outline existing approaches for pKa calculations, emphasizing methods that were used by the participants in calculating the blind pKa values in the first round of the cooperative. We then point out some of the difficulties encountered by the participating groups in making their blind predictions, and finally try to provide some insights for future developments aimed at improving the accuracy of pKa calculations.

  6. A study of switchgrass pyrolysis: Product variability and reaction kinetics

    NASA Astrophysics Data System (ADS)

    Bovee, Jonathan Matthew

    Samples of the same cultivar of cave-in-rock switchgrass were harvested from plots in Frankenmuth, Roger City, Cass County, and Grand Valley, Michigan. It was determined that variation exists, between locations, among the pyrolytic compounds which can lead to variability in bio-oil and increased processing costs at bio-refineries to make hydrocarbon fuels. Washed and extractives-free switchgrass samples, which contain a lower alkali and alkaline earth metals content than untreated samples, were shown to produce lower amounts of acids, esters, furans, ketones, phenolics, and saccharides and also larger amounts of aldehydes upon pyrolysis. Although the minerals catalyzed pyrolytic reactions, there was no evidence indicating their effect on reducing the production of anhydrosugars, specifically levoglucosan. To further link minerals present in the biomass to a catalytic pathway, mathematic models were employed to determine the kinetic parameters of the switchgrass. While the calculated activation energies of switchgrass, using the FWO and KAS methods, were 227.7 and 217.8 kJ/mol, correspondingly, it was concluded that the activation energies for the switchgrass hemicellulose and cellulose peaks were 115.5 and 158.2 kJ/mol, respectively, using a modified model-fitting method. The minerals that effect the production of small molecules and levoglucosan also have an observable catalytic effect on switchgrass reaction rate, which may be quantifiable through the use of reaction kinetics so as to determine activation energy.

  7. COMPASS Final Report: Lunar Relay Satellite (LRS)

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; McGuire, Melissa L.

    2012-01-01

    The Lunar Relay Satellite (LRS) COllaborative Modeling and Parametric Assessment of Space Systems (COMPASS) session was tasked to design a satellite to orbit in an elliptical lunar polar orbit to provide relay communications between lunar South Pole assets and the Earth. The design included a complete master equipment list, power requirement list, configuration design, and brief risk assessment and cost analysis. The LRS is a half-TDRSS sized box spacecraft, which provides communications and navigation relay between lunar outposts (via Lunar Communications Terminals (LCT)) or Sortie parties (with user radios) and large ground antennas on Earth. The LRS consists of a spacecraft containing all the communications and avionics equipment designed by NASA Jet Propulsion Laboratory s (JPL) Team X to perform the relay between lunar-based assets and the Earth. The satellite design is a standard box truss spacecraft design with a thermal control system, 1.7 m solar arrays for 1 kWe power, a 1 m diameter Ka/S band dish which provides relay communications with the LCT, and a Q-band dish for communications to/from the Earth based assets. While JPL's Team X and Goddard Space Flight Center s (GSFC) I M Design Center (IMDC) have completed two other LRS designs, this NASA Glenn Research Center (GRC) COMPASS LRS design sits between them in terms of physical size and capabilities.

  8. Latvian Waste Management Modelling in View of Environmental Impact Reduction / Latvijas Atkritumu SAIMNIECĪBAS ATTĪSTĪBA un TĀS RADĪTĀS Ietekmes UZ Vidi SAMAZINĀŠANAS MODELĒŠANA

    NASA Astrophysics Data System (ADS)

    Teibe, I.; Bendere, R.; Arina, D.

    2013-12-01

    In the work, the life-cycle assessment approach is applied to the planning of waste management development in a seaside region (Piejūra) using the Waste Management Planning System (WAMPS) program. In Latvia, the measures to be taken for the climate change mitigation are of utmost importance - especially as related to the WM performance, since a disposal of biodegradable waste presents the primary source of GHG emissions. To reduce the amount of such waste is therefore one of the most significant goals in the State WM plan for 2013-2020, whose adoption is the greatest challenge for municipalities. The authors analyse seven models which involve widely employed biomass processing methods, are based on experimental data and intended for minimising the direct disposal of organic mass at the solid waste landfills. The numerical results obtained evidence that the thermal or biotechnological treatment of organic waste substantially reduces the negative environmental impact of WM practices - by up to 6% as compared with the currently existing. Klimata pārmaiņu samazināšanas pasākumi Latvijā atkritumu saimniecības sektorā ir īpaši svarīgi. jo bioloģiski sadalāmo atkritumu apglabāšana ir viens no būtiskākajiem SEG emisiju avotiem valstī. Pētījumā modelēti virkne sadzīves atkritumu apsaimniekošanas modeļi. kas ietver plašāk izmantotās biomasas pārstrādes metodes un samazina tiešu organiskās masas apglabāšanu cieto sadzīves atkritumu poligonos. Atkritumu apsaimniekošanas modeļu radītās vides ietekmes novērtēšanai izmantota WAMPS (Waste Management Planning System) programma, kas balstīta uz atkritumu apsaimniekošanas procesu dzīves cikla novērtējumu vienā no desmit Latvijas atkritumu apsaimniekošanas reģioniem - Piejūra. Iegūtie kvantitatīvie rezultāti norāda. ka organiskās atkritumu masas pārstrāde un stabilizēšana, izmantojot biotehnoloģijas vai termisko pārstrādi, būtiski samazina atkritumu apsaimniekošanas rad

  9. Development of Dynamically Optimized Wireless Transmission System for Wireless Sensor Networks in Highrise Apartment Building Heating Systems / Optimizētas Dinamiskās Bezvadu Sensoru Tīklu Pārraides Risinājuma Izstrāde Daudzstāvu Ēku Apkures Sistēmas Parametru Izgūšanai Un Vadībai

    NASA Astrophysics Data System (ADS)

    Isakovs, V.; Kondratjevs, K.; Kunicina, N.; Freliha, B.; Zabasta, A.

    2015-08-01

    Smart meters will be at the centre of the integrated solutions, including interaction with other networks in the next decade. The developed solution for multi-apartment building ventilation and heating parameter monitoring aims to increase energy efficiency and optimal control of the existing system. Dynamic control of heat and ventilation systems, heat loss detection, calculation and mitigation, and individual heat energy accounting are difficult tasks to accomplish. This article deals with the data transmission system using battery powered ISM band radio transmitters. The temperature measurement sensors with cumulative temperature reading are used as sensor part for this solution. The offered approach to monitoring system is used for overall building and individual apartment monitoring. Data coding and antenna designs are explained for this particular application. Daudzstāvu ēkas, kuras nav sākotnēji plānotas integrācijai ar ēku vadības sistēmām, rada kompleksu problemātisko vidi modernizācijai. Vadu sensoru sistēmu uzstādīšana šādās ēkās kļūst nepraktiska vai pat neiespējama. Šī iemesla dēļ ir nepieciešamas efektīvas bezvadu sensoru sistēmas, kas spētu nodrošināt mērījumu nogādi, ņemot vērā daudzstāvu ēku specifiku. Rakstā tiek piedāvāts bezvadu sensoru tīkla risinājums efektīvai datu pārraidei siltumapgādes sistēmas parametru izgūšanai. Tiek izstrādāta un aprobēta specializētā virziena antena efektīvai radio telegrammu savākšanai no dzīvokļiem, nogādājot mērījumus datu koncentratoros. Ziņojumu telegrammu efektīvai pārraidei tiek piedāvāta datu kodēšanas kumulatīvā metode. Piedāvātais risinājums pielietojams gan jaunām, gan esošām ēkām. Izgūtie dati ir pielietojami siltuma apgādes sistēmas uzraudzībai, regulēšanai, kā arī individuālā siltuma patēriņa tarifikācijai.

  10. Testing alternative tectonic models of Palaeotethys in the E Mediterranean region: new U-Pb and Lu-Hf isotopic analyses of detrital zircons from Late Carboniferous and Late Triassic sandstones associated with the Anatolide and Tauride blocks (S Turkey)

    NASA Astrophysics Data System (ADS)

    Ustaömer, Timur; Ayda Ustaömer, Petek; Robertson, Alastair; Gerdes, Axel

    2016-04-01

    Alternative tectonic models of Palaeotethys during Late Palaeozoic-Early Mesozoic time infer: 1. southward subduction beneath the north margin of Gondwana; 2. northward subduction beneath the south margin of Eurasia, or 3. double subduction (northwards and southwards), at least during Late Carboniferous. U-Pb and Lu-Hf isotopic analysis of detrital zircons, extracted from sandstones, can provide strong indications of age and identity of source terranes. Here, we consider the provenance of both Late Carboniferous and Late Triassic sandstones from both relatively allochthonous and relatively autochthonous units that are all spatially associated with the Anatolide and Tauride continental blocks. The relatively allochthonous units are sandstones (3 samples) from the Late Carboniferous Aladaǧ Nappe (Tauride; in the east), the Konya Complex (Anatolide; central area) and the Karaburun Mélange (Tauride-related; in the west). The relatively autochthonous units are Late Triassic sandstones (4 samples) from the Üzümdere Formation, the Kasımlar Formation (both western Taurides) and the Güvercinlik Formation (Karaburun Peninsula-Tauride related; far west). The Late Carboniferous sandstones from the three relatively allochthonous units are dominated by Precambrian zircon populations, the age distribution of which suggests derivation from two contrasting source regions: First, a NE African-type source (i.e. Saharan craton) for the sandstones of the Konya Mélange and the Aladaǧ Nappe because these sediments have prominent zircon populations dated at 0.5-0.7, 0.8 and 0.9-1.1 Ga. Palaeozoic zircons are minimal in the sandstones of the Aladaǧ Nappe and the Konya Complex (3 and 5% of the whole data, respectively) and are confined to Cambrian to Ordovician. Secondly, a contrasting NW African-type source is inferred for sandstone from the Karaburun Mélange because of the marked absence of Tonian-Stenian zircons and the predominance of ~2 Ga zircons over ~2.5 Ga zircons. In

  11. Operative and technological management of super-large united power grids: lessons of major world's blackouts

    NASA Astrophysics Data System (ADS)

    Brinkis, K.; Kreslins, V.; Mutule, A.

    2014-02-01

    Power system (PS) blackouts still persist worldwide, evidencing that the existing protective structures need to be improved. The discussed requirements and criteria to be met for joint synchronous operation of large and super-large united PSs should be based on close co-ordination of operative and technological management of all PSs involved in order to ensure secure and stable electricity supply and minimise or avoid the threat of a total PS blackout. The authors analyse the July 2012 India blackout - the largest power outage in history, which affected over 620 million people, i.e. half of India's population and spread across its 22 states. The analysis is of a general character, being applicable also to similar blackouts that have occurred in Europe and worldwide since 2003. The authors summarise and develop the main principles and methods of operative and technological management aimed at preventing total blackouts in large and super-large PSs. Neskatoties uz sasniegumiem elektroenerģētikas jomā un energosistēmu nepārtrauktu modernizāciju, pasaulē regulāri notiek sabrukumu avārijas. Rakstā apskatīti lielu un superlielu energosistēmu apvienību savstarpējas sinhronas darbības nodrošinājuma prasības un kritēriji, kas pamatojas uz operatīvās un tehnoloģiskās vadības ciešu koordināciju starp energosistēmām. Savstarpējas sinhronas darbības nodrošinājuma prasībām un kritērijiem ir izšķiroša nozīme, lai panāktu elektroapgādes drošumu un stabilitāti katrā energosistēmā, kas darbojas apvienotas energosistēmas sastāvā. Šo prasību un kritēriju ievērošana sekmē totālo avāriju izcelšanās iespēju samazināšanu un to novēršanu. Indijas 2012.gada totālo avāriju un citu analogo avāriju Eiropā un Amerikā analīze un izvērtējums laika posmā no 2003.gada, deva iespēju apkopot un izstrādāt lielu un superlielu energosistēmu operatīvās un tehnoloģiskās vadības principus un metodoloģiju, lai novērstu vai

  12. Assessment of Wind Shear and Wind Energy Potential in the Baltic Sea Region of Latvia

    NASA Astrophysics Data System (ADS)

    Bezrukovs, V.; Bezrukovs, Vl.; Zacepins, A.; Komashilovs, V.

    2015-04-01

    The paper is devoted to the investigation into the wind energy potential based on long-term observations of the wind speed and energy density fluctuations at heights from 10 to 160 m on the Baltic Sea coast of Latvia. During the observations (2004 - 2013), the wind speed and direction values were measured, and the statistical database was accumulated using a LOGGER 9200 Symphonie measuring systems mounted on 60 m masts - one on the western coast and another on the north-east of Latvia. From June 2011 to May 2012, these measurements were complemented with the data for the heights from 40 to 160 m obtained by means of a ZephIR lidar and with the metrological data provided by "Latvian Environment, Geology and Meteorology Centre" for the same period. The graphs of seasonal fluctuations in the wind speed were obtained for the heights up to 160 m by measurements over the period of 2007 - 2013. The results of the research on the wind speed distribution up to 200 m are promising for evaluation of the wind energy potential of Latvia and will be helpful in assessment of prospective sites for construction of WPPs. Zinātniskais raksts ir veltīts pētījumam par vēja enerģijas potenciālu Latvijas teritorijā, Baltijas jūras piekrastē, balstoties uz ilgtermiņa vēja ātruma un vēja enerģijas blīvuma svārstību novērojumiem no 10 līdz 160 metriem augstumā. Vēja ātruma un vēja virziena mērījumu dati tika iegūti un apkopoti statistiskajā datubāzē laika periodā no 2004 līdz 2013. gadam, izmantojot mērīšanas sistēmu LOGGER 9200 Symphonie, kas bija ierīkotā uz 60 metru augsta masta - viena rietumu piekrastē un otra Latvijas ziemeļu-austrumos. No 2011. gada jūnija līdz 2012. gada maijam mērījumu datubāze tika papildināta ar datiem, kas tika iegūti ar lidaruZephIR augstumos no 40 līdz 160 metriem, un datiem no "Latvijas Vides, ģeoloģijas un meteoroloģijas centra" tam pašam laika periodam. Analizējot mērījumus 2007. g.-2013. g., grafiki ar

  13. Obtaining a Well-Aligned ZnO Nanotube Array Using the Hydrothermal Growth Method / Labi Sakārtotu Zno Nanocauruļu Kopu Iegūšana, Izmantojot Hidrotermālo Metodi

    NASA Astrophysics Data System (ADS)

    Krasovska, M.; Gerbreders, V.; Paskevics, V.; Ogurcovs, A.; Mihailova, I.

    2015-10-01

    Optimal growing parameters have been found using the hydrothermal method to obtain well-aligned vertical ZnO nanorod and nanotube arrays. The influence of different growing factors (such as temperature, growing solution concentration, method of obtaining seed layer and condition) on nanotube morphology and size is described in the paper. Well-structured ZnO nanotubes have been obtained by using a selfselective etching method with lowering temperatures of growth during the hydrothermal process. It is shown that the optical properties of the nanostructure arrays obtained are sensitive to the medium in which they are placed, which is why they can be used as sensors for pure substance detection and in different solutions for impurity determination. Dotajā darbā tika noteikti optimāli parametri labi sakārtotu ZnO nanocaurulīšu kopu iegūšanai, izmantojot hidrotermālo metodi ar temperatūras pazemināšanu, jeb t.s. selektīvu pa\\vskodināšanas metodi (self-selective etching), ir uzsvērtas šās metodes priekšrocības salīdzinājumā ar ķīmiskās kodināšanas metodi, kā arī tika aprakstīta dažādu augšanas faktora (tādu, ka darba šķīduma koncentrācija, augšanas temperatūra un laiks, iedīgļu slāņa iegūšanas veids un iegūšanas parametri) ietekme uz iegūtu nanostraktūra morfoloģiju. Tika konstatēts, ka noteicošu lomu ZnO nanocaurulīšu audzēšanas procesā spēlē iedīgļu slāņa graudu izmēri, kas savā staipā nosaka augošu nanostieņu izmērus un to tendenci pie pa\\vskodināšanas. Rentgenogrannnas parāda, ka iegūtām pie noteiktiem parametriem ZnO nanostruktūrām piemīt augsta kristāliskuma pakāpe un sakārtotība vertikālā virzienā. Optiskie mērījumi parāda, ka ZnO nanocauralītes ir jutīgas gan pret tīrām vielām (ūdens, spirts), gan pret dažādiem šķīdumiem, kas ļauj izmantot tos kā pie­jaukumu sensora. Salīdzinājumā ar ZnO nanostieņiem caurulīšu jūtība pieaug, jo pieaug nanostrakt

  14. Histidine-607 and histidine-643 provide important interactions for metal support of catalysis in phosphodiesterase-5.

    PubMed

    Francis, S H; Turko, I V; Grimes, K A; Corbin, J D

    2000-08-01

    Class I cyclic nucleotide phosphodiesterases (PDEs) share a catalytic domain containing 18 invariant residues. In cGMP-binding cGMP-specific PDE (PDE5), we showed previously that point mutation of nine of these profoundly decreases k(cat) when the assay is conducted in the presence of Mg(2+); seven of these are in the prototypical metal-binding motifs A and B (HX(3)HX(n)()E) that we identified earlier. Tandem arrangement of two of these metal-binding motifs in PDEs is novel, and whether residues within these motifs are involved in metal support of catalytic activity is a fundamental question in this field. This report shows that mutation of either His-607 (A motif) or His-643 (B motif) to alanine profoundly diminishes support of PDE catalysis by Mn(2+) or Mg(2+), but mutation of His-647 in B motif or of Glu in either motif does not. H607A and H643A mutants have much greater maximum catalytic rates supported by Mn(2+) than that by Mg(2+); catalytic activity of H603A mutant is supported weakly by either. In H607A and H643A, K(a)s for Mn(2+) and Mg(2+) are increased, but the effect of Mn(2+) is 2-fold greater than that of Mg(2+) in each. Mutation of any of the other conserved residues (Asn-604, Asp-644, His-675, Asp-714, and Asp-754) causes unremarkable changes in Mn(2+) or Mg(2+) support of catalysis. This study identifies specific residues in PDE5 that contribute to interactions with catalytically relevant metals. The combined data suggest that despite a high degree of sequence similarity between each HX(3)HX(n)()E motif in PDEs and certain metallo-endopeptidases, PDEs employ a distinct complement of residues for interacting with metals involved in catalysis. PMID:10924156

  15. Differences in Organizational Structure of Insulin Receptor on Rat Adipocyte and Liver Plasma Membranes: Role of Disulfide Bonds

    NASA Astrophysics Data System (ADS)

    Schweitzer, John B.; Smith, Robert M.; Jarett, Leonard

    1980-08-01

    Binding of 125I-labeled insulin to rat liver and adipocyte plasma membranes has been investigated after treatment of the membranes with agents that modify disulfide bonds or sulfhydryl groups. Dithiothreitol, a disulfide-reducing agent, produced a bimodal response in adipocyte plasma membranes with dose-dependent increases in binding occurring over the range of 0-1 mM dithiothreitol; 5 mM dithiothreitol produced decreased binding. Insulin binding reached its maximal increase at 1 mM and was 3 times control values. Scatchard analysis of the 1 mM dithiothreitol effect revealed a straight line plot indicative of one class of sites with a Ka of 1.0× 108 M-1 which is intermediate between the two Kas obtained from the curvilinear Scatchard plot of control membranes. There was a 20-fold increase in the number of intermediate-affinity receptors compared to high-affinity receptors. The increased 125I-labeled insulin binding after dithiothreitol treatment was reversed by oxidized glutathione in a dose-dependent manner. Interposition of treatment with N-ethylmaleimide, an alkylating agent, prevented oxidized glutathione from reversing the dithiothreitol effect. Reduced glutathione produced the same effect as dithiothreitol. Liver plasma membranes treated with up to 1 mM dithiothreitol exhibited a maximum increase in insulin binding of 20% compared to control. Dithiothreitol at 5 mM decreased insulin binding below that of control membranes. The results indicate that the dithiothreitol effect on insulin binding to adipocyte plasma membranes is due to disruption of disulfide bonds, and that the structural organization of the insulin receptor on the plasma membranes is different for liver and for adipose tissue. The data imply that the insulin receptors on the plasma membrane of adipocytes possess at least two functionally distinct subclasses of disulfide bond but liver insulin receptors do not.

  16. Unified Model of Multiple Wind Turbines

    NASA Astrophysics Data System (ADS)

    Mutule, A.; Kochukov, O.

    2014-08-01

    An approach is proposed to the modelling of wind farms in the electric power system long-term planning. It allows a specialist to perform calculations based on scanty information and offers a set of ready-to-use data for easy, fast, and precise modelling. The authors exemplify the calculations of wind speed probability density and power curves and give an idea for relevant corrections. They also show how to pass from a single wind turbine model to the unified model of multiple wind turbines which would meet the requirements of long-term planning tasks. The paper presents the data on wind farms that are operating in UK and Oceania Rakstā ir apskatīta vēja elektrostaciju modelēšana ilgtermiņa attīstības plānošanas uzdevumos. Modelēšana tika veikta, izmantojot ierobežotu datu apjomu, kuri bija piejami lietotājam. Gatavie dati deva iespēju veikt ātru un precīzu modelēšanu. Raksts piedāva metodi kā pāriet no viena vēja ģeneratora modeli uz vēja elektrostaciju (vairāki vēja ģeneratori) modeli, kas atbilst ilgtermiņa attīstības plānošanas prasībām. Rakstā atspoguļoti dati no Okeānijas un Lielbritānijas eksistējošām vēja elektrostacijām

  17. Natural Variation of Cold Deacclimation Correlates with Variation of Cold-Acclimation of the Plastid Antioxidant System in Arabidopsis thaliana Accessions.

    PubMed

    Juszczak, Ilona; Cvetkovic, Jelena; Zuther, Ellen; Hincha, Dirk K; Baier, Margarete

    2016-01-01

    Temperature variations impact on the balance between photosynthetic electron transport and electron-consuming assimilation reactions and transiently increase generation of reactive oxygen species (ROS). Previous studies demonstrated that the expression of C-repeat binding factors (CBFs), which activate cold acclimation reactions, respond to chloroplast ROS signals and that cold deacclimation is partly halted for days after the transfer of acclimated plants to optimal growth conditions in four Arabidopsis accessions from cold-continental habitats. We hypothesized that these accessions differ from others in the regulation of the plastid antioxidant system (PAS). In the present study, we compared the expression intensity of the 12 most prominent PAS genes for peroxidases, superoxide dismutase and low molecular weight antioxidant regenerating enzymes in 10 Arabidopsis accessions with regulation of CBF and COR (cold regulated genes) transcript levels and cold-regulated metabolite levels prior to cold, after 2 week long cold acclimation and during the first 3 days of deacclimation. In the accessions with prolonged activation of cold responses, by trend, weaker induction of various cold-inducible PAS genes and stronger decreases in the expression of negatively cold-regulated PAS genes were observed. Low PAS gene expression delayed the post-cold decrease in H2O2 levels after transfer of the plants from cold to optimal growth conditions. We conclude that weaker expression of various PAS genes in the cold is an adapted strategy of the Arabidopsis accessions N14, N13, Ms-0, and Kas-1 to avoid full inactivation of cold-responses in the first days after the end of the cold period. PMID:27014325

  18. Effects of surface chemistry and size on iron oxide nanoparticle delivery of oligonucleotides

    NASA Astrophysics Data System (ADS)

    Shen, Christopher

    The discovery of RNA interference and the increasing understanding of disease genetics have created a new class of potential therapeutics based on oligonucleotides. This therapeutic class includes antisense molecules, small interfering RNA (siRNA), and microRNA modulators such as antagomirs (antisense directed against microRNA) and microRNA mimics, all of which function by altering gene expression at the translational level. While these molecules have the promise of treating a host of diseases from neurological disorders to cancer, a major hurdle is their inability to enter cells on their own, where they may render therapeutic effect. Nanotechnology is the engineering of materials at the nanometer scale and has gained significant interest for nucleic acid delivery due to its biologically relevant length-scale and amenability to multifunctionality. While a number of nanoparticle vehicles have shown promise for oligonucleotide delivery, there remains a lack of understanding of how nanoparticle coating and size affect these delivery processes. This dissertation seeks to elucidate some of these factors by evaluating oligonucleotide delivery efficiencies of a panel of iron oxide nanoparticles with varying cationic coatings and sizes. A panel of uniformly-sized nanoparticles was prepared with surface coatings comprised of various amine groups representing high and low pKas. A separate panel of nanoparticles with sizes of 40, 80, 150, and 200 nm but with the same cationic coating was also prepared. Results indicated that both nanoparticle surface coating and nanoparticle hydrodynamic size affect transfection efficiency. Specific particle coatings and sizes were identified that gave superior performance. The intracellular fate of iron oxide nanoparticles was also tracked by electron microscopy and suggests that they function via the proton sponge effect. The research presented in this dissertation may aid in the rational design of improved nanoparticle delivery vectors for

  19. A Mechanistic Study of Protein Phosphatase-1 (PP1), A Catalytically Promiscuous Enzyme

    PubMed Central

    McWhirter, Claire; Lund, Elizabeth A.; Tanifum, Eric A.; Feng, Guoqiang; Sheikh, Qaiser; Hengge, Alvan C.; Williams, Nicholas H.

    2009-01-01

    The reaction catalyzed by the protein phosphatase-1 (PP1) has been examined by linear free energy relationships and kinetic isotope effects. With the substrate 4-nitrophenyl phosphate (4NPP), the reaction exhibits a bell-shaped pH-rate profile for kcat/KM indicative of catalysis by both acidic and basic residues, with kinetic pKas of 6.0 and 7.2. The enzymatic hydrolysis of a series of aryl monoester substrates yields a Brønsted βlg of -0.32, considerably less negative than that of the uncatalyzed hydrolysis of monoester dianions (-1.23). Kinetic isotope effects in the leaving group with the substrate 4NPP are 18(V/K)bridge = 1.0170 and 15(V/K) = 1.0010 which, compared against other enzymatic KIEs with and without general acid catalysis, are consistent with a loose transition state with partial neutralization of the leaving group. PP1 also efficiently catalyzes the hydrolysis of 4-nitrophenyl methylphosphonate (4NPMP). The enzymatic hydrolysis of a series of aryl methylphosphonate substrates yields a Brønsted βlg of -0.30, smaller than the alkaline hydrolysis (-0.69) and similar to the βlg measured for monoester substrates, indicative of similar transition states. The KIEs and the βlg data point to a transition state for the alkaline hydrolysis of 4NPMP that is similar to that of diesters with the same leaving group. For the enzymatic reaction of 4NPMP, the KIEs are indicative of a transition state that is somewhat looser than the alkaline hydrolysis reaction, and similar to the PP1-catalyzed monoester reaction. The data cumulatively point to enzymatic transition states for aryl phosphate monoester and aryl methylphosphonate hydrolysis reactions that are much more similar to one another than the nonenzymatic hydrolysis reactions of the two substrates. PMID:18798625

  20. Uncovering the Thermodynamics of Monomer Binding for RNA Replication

    PubMed Central

    2015-01-01

    The nonenzymatic replication of primordial RNA is thought to have been a critical step in the origin of life. However, despite decades of effort, the poor rate and fidelity of model template copying reactions have thus far prevented an experimental demonstration of nonenzymatic RNA replication. The overall rate and fidelity of template copying depend, in part, on the affinity of free ribonucleotides to the RNA primer–template complex. We have now used 1H NMR spectroscopy to directly measure the thermodynamic association constants, Kas, of the standard ribonucleotide monophosphates (rNMPs) to native RNA primer–template complexes. The binding affinities of rNMPs to duplexes with a complementary single-nucleotide overhang follow the order C > G > A > U. Notably, these monomers bind more strongly to RNA primer–template complexes than to the analogous DNA complexes. The relative binding affinities of the rNMPs for complementary RNA primer–template complexes are in good quantitative agreement with the predictions of a nearest-neighbor analysis. With respect to G:U wobble base-pairing, we find that the binding of rGMP to a primer–template complex with a 5′-U overhang is approximately 10-fold weaker than to the complementary 5′-C overhang. We also find that the binding of rGMP is only about 2-fold weaker than the binding of rAMP to 5′-U, consistent with the poor fidelity observed in the nonenzymatic copying of U residues in RNA templates. The accurate Ka measurements for ribonucleotides obtained in this study will be useful for designing higher fidelity, more effective RNA replication systems. PMID:25901790

  1. [Pharmacological effects of N-acetyl-L-cysteine on the respiratory tract. (I). Quantitative and qualitative changes in respiratory tract fluid and sputum (author's transl)].

    PubMed

    Kogi, K; Saito, T; Kasé, Y; Hitoshi, T

    1981-06-01

    The following three experiments were performed to determine the effects of N-acetyl-L-cysteine (NAC) on the quantity and quality of respiratory tract fluid (RTF) and sputum. All drugs used were administered into the stomach through a gastric tube. 1) Indirect measurement of bronchial secretion in rats, which was expressed by the amounts of dye excreted into the respiratory tract, was carried out according the the Sakuno's method, with some modification. Some expectorants of the secretomotor type, such as bromhexine and pilocarpine, significantly increased the secretion, even at low doses. On the other hand, mucolytic agents such as NAC augmented the secretion only in doses of 500 to 1500 mg/kg. 2)As a direct method of measurements, Kasé's modification of Perry and Boyd's method was used to collect RTF, quantitatively, from rabbits. The RTF of healthy rabbits was colorless and watery. The administration of NAC in doses of 500 to 1500 mg/kg augmented the output volume and RTF became slightly turbid, probably due to an increase in the viscous mucus. 3) Rabbits with subacute bronchitis were prepared by long-term exposure to air contaminated with SO2 gas and sputa were collected before and after administration of NAC, respectively, according to the Kase's method. The sputa were opalescent and viscous gel included nodular masses. The administration of NAC, 1000 and 1500 mg/kg resulted in a dose dependent decrease in the relative viscosity. The percent-decreased in viscosity with NAC was statistically correlated with that in amounts of dry matter, those in protein and polysaccharide in the sputa. From the results described above, it was concluded that NAC given into the stomach can liquefy sputum by splitting mucoprotein disulphide linkages, that is, altering the rheological characteristics of sputum to facilitate expectoration. PMID:7286849

  2. Assessing Colorectal Cancer Screening Behaviors and Knowledge among At-Risk Hispanics in Southern New Mexico*

    PubMed Central

    Sanchez, Janeth I.; Palacios, Rebecca; Thompson, Beti; Martinez, Vanessa; O’Connell, Mary A.

    2014-01-01

    Purpose Colorectal cancer (CRC) mortality rates in New Mexico (NM) continue to be higher than national rates. Hispanic CRC mortality rates in NM surpass those of overall Hispanics in the US. This study was designed to characterize and understand factors contributing to low CRC screening rates in this border region. Methods A CRC Knowledge Assessment Survey (KAS) was administered in either English or Spanish to 247 individuals attending community events throughout southern NM. A subset of these individuals completed an online CRC risk assessment survey managed by the National Cancer Institute (NCI). Data analysis tested for significant differences in knowledge, physician-patient CRC interactions, CRC risk level perception, and screening rates across diverse ethnic and age groups. Results Both CRC knowledge and physician-patient CRC interactions were positively associated with participant screening history. Significant age and ethnic differences for CRC knowledge, physician-patient CRC interactions, and screening history in the NM border sample were also seen. Age-eligible Hispanics (50+) as well as those less than 50 years of age had lower CRC knowledge and were less likely to engage in physician-patient CRC interactions than non-Hispanic Whites (NHWs). The age-eligible Hispanics also reported lower CRC screening rates than their NHW counterparts. Conclusions Low CRC knowledge and limited physician-patient CRC interactions appear to contribute to low screening rates in this NM population. Expanding education and outreach efforts for this border population are essential to promote early CRC detection and thereby decrease overall CRC mortality rates. PMID:25621179

  3. The Effect of Mutation of Carboxyl Side-Chain Amino Acids Near the Heme on the Midpoint Potentials and Ligand Binding Constants of Nitrophorin 2 and Its NO, Histamine and Imidazole Complexes

    PubMed Central

    Berry, Robert E.; Shokhirev, Maxim N.; Ho, Arthur Y. W.; Yang, Fei; Shokhireva, Tatiana K.; Zhang, Hongjun; Weichsel, Andrzej; Montfort, William R.; Walker, F. Ann

    2009-01-01

    Nitrophorins (NPs) are a group of NO-carrying heme proteins found in the saliva of a bloodsucking insect from tropical Central and South America, Rhodnius prolixus, the “kissing bug”. NO is kept stable for long periods of time by binding it as an axial ligand to a ferriheme center. The fact that the nitrophorins are stabilized as FeIII-NO proteins is a unique property, for most heme proteins are readily autoreduced by excess NO, and bind NO to the Fe(II) heme irreversibly (Kds in the pM range). In contrast, the nitrophorins, as Fe(III) heme centers, have Kds in the μM to nM range, and thus allow NO to dissociate upon dilution following injection into the tissues of the victim. This NO can cause vasodilation, and thereby allow more blood to be transported to the site of the wound. We have prepared thirteen site-directed mutants of three major nitrophorins, NP2, NP1 and NP4, to investigate the stabilization of the ferric–NO heme center and preservation of reversible binding that facilitates these proteins’ NO storage, transport and release functions. Of the mutations in which Glu and/or Asp were replaced by Ala, most of these carboxyls show a significant role stabilizing FeIII-NO over FeII-NO, with buried E53 of NP2 or E55 of NP1 and NP4 being the most important, and partially buried D29 of NP2 or D30 of NP4 being second in importance. The pKas of the carboxyl groups studied vary significantly, but all are largely deprotonated at pH 7.5 except E124. PMID:19175316

  4. Indole-3-acetic acid (IAA) induced changes in oil content, fatty acid profiles and expression of four fatty acid biosynthetic genes in Chlorella vulgaris at early stationary growth phase.

    PubMed

    Jusoh, Malinna; Loh, Saw Hong; Chuah, Tse Seng; Aziz, Ahmad; Cha, Thye San

    2015-03-01

    Microalgae lipids and oils are potential candidates for renewable biodiesel. Many microalgae species accumulate a substantial amount of lipids and oils under environmental stresses. However, low growth rate under these adverse conditions account for the decrease in overall biomass productivity which directly influence the oil yield. This study was undertaken to investigate the effect of exogenously added auxin (indole-3-acetic acid; IAA) on the oil content, fatty acid compositions, and the expression of fatty acid biosynthetic genes in Chlorella vulgaris (UMT-M1). Auxin has been shown to regulate growth and metabolite production of several microalgae. Results showed that oil accumulation was highest on days after treatment (DAT)-2 with enriched levels of palmitic (C16:0) and stearic (C18:0) acids, while the linoleic (C18:2) and α-linolenic (C18:3n3) acids levels were markedly reduced by IAA. The elevated levels of saturated fatty acids (C16:0 and C18:0) were consistent with high expression of the β-ketoacyl ACP synthase I (KAS I) gene, while low expression of omega-6 fatty acid desaturase (ω-6 FAD) gene was consistent with low production of C18:2. However, the increment of stearoyl-ACP desaturase (SAD) gene expression upon IAA induction did not coincide with oleic acid (C18:1) production. The expression of omega-3 fatty acid desaturase (ω-3 FAD) gene showed a positive correlation with the synthesis of PUFA and C18:3n3. PMID:25583439

  5. Molecular mechanisms for generating transmembrane proton gradients

    PubMed Central

    Gunner, M.R.; Amin, Muhamed; Zhu, Xuyu; Lu, Jianxun

    2013-01-01

    Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side. PMID:23507617

  6. Cine-servo lens technology for 4K broadcast and cinematography

    NASA Astrophysics Data System (ADS)

    Nurishi, Ryuji; Wakazono, Tsuyoshi; Usui, Fumiaki

    2015-09-01

    Central to the rapid evolution of 4K image capture technology in the past few years, deployment of large-format cameras with Super35mm Single Sensors is increasing in TV production for diverse shows such as dramas, documentaries, wildlife, and sports. While large format image capture has been the standard in the cinema world for quite some time, the recent experiences within the broadcast industry have revealed a variety of requirement differences for large format lenses compared to those of the cinema industry. A typical requirement for a broadcast lens is a considerably higher zoom ratio in order to avoid changing lenses in the middle of a live event, which is mostly not the case for traditional cinema productions. Another example is the need for compact size, light weight, and servo operability for a single camera operator shooting in a shoulder-mount ENG style. On the other hand, there are new requirements that are common to both worlds, such as smooth and seamless change in angle of view throughout the long zoom range, which potentially offers new image expression that never existed in the past. This paper will discuss the requirements from the two industries of cinema and broadcast, while at the same time introducing the new technologies and new optical design concepts applied to our latest "CINE-SERVO" lens series which presently consists of two models, CN7x17KAS-S and CN20x50IAS-H. It will further explain how Canon has realized 4K optical performance and fast servo control while simultaneously achieving compact size, light weight and high zoom ratio, by referring to patent-pending technologies such as the optical power layout, lens construction, and glass material combinations.

  7. Can Citizen Science Survey Non-indigenous Fish Species in the Eastern Mediterranean Sea?

    NASA Astrophysics Data System (ADS)

    Bodilis, P.; Louisy, P.; Draman, M.; Arceo, H. O.; Francour, P.

    2014-01-01

    Engaging non-scientists to survey ecosystems, a process known as citizen science has been adopted worldwide. For the first time, this was applied to monitor fish assemblages in the Kas Peninsula, Turkey, an area known for its important Lessepsian fish populations. For 3 years (2004, 2007 and 2010), fish assemblages were surveyed using underwater visual census by transect method. A total of 29 species was observed, seven of which were Lessepsian species. Results show a significant increase in the Lessepsian species over the study period. In 2004, they represented 34 % of the total abundance, increasing to >61 % in 2010. Differences were observed in the progression of populations between two invasive herbivores, Siganus rivulatus and Siganus luridus (Siganidae), and two native herbivores, Sparisoma cretense (Scaridae) and Sarpa salpa (Sparidae). The siganids were recorded each year in all sites, whereas S. cretense was regularly observed in fewer numbers, while S. salpa was rarely censused. Abundance of Siganus spp. increased threefold in 6 years while abundances of S. cretense and S. salpa remained stable. S. rivulatus was the most abundant among the four species. Its competitive superiority may be due to its greater adaptability to fluctuating environmental conditions and biological traits, e.g. rapid growth, earlier sexual maturity, high fecundity. Because siganids are herbivorous, their presence can strongly impact algal ecosystems. It is then important to follow their spreading at a large scale, but this can be challenging due to the limited number of scientists. Adopting citizen science can thus be a useful strategy to monitor the spread of invasive species in the Mediterranean.

  8. Natural Variation of Cold Deacclimation Correlates with Variation of Cold-Acclimation of the Plastid Antioxidant System in Arabidopsis thaliana Accessions

    PubMed Central

    Juszczak, Ilona; Cvetkovic, Jelena; Zuther, Ellen; Hincha, Dirk K.; Baier, Margarete

    2016-01-01

    Temperature variations impact on the balance between photosynthetic electron transport and electron-consuming assimilation reactions and transiently increase generation of reactive oxygen species (ROS). Previous studies demonstrated that the expression of C-repeat binding factors (CBFs), which activate cold acclimation reactions, respond to chloroplast ROS signals and that cold deacclimation is partly halted for days after the transfer of acclimated plants to optimal growth conditions in four Arabidopsis accessions from cold-continental habitats. We hypothesized that these accessions differ from others in the regulation of the plastid antioxidant system (PAS). In the present study, we compared the expression intensity of the 12 most prominent PAS genes for peroxidases, superoxide dismutase and low molecular weight antioxidant regenerating enzymes in 10 Arabidopsis accessions with regulation of CBF and COR (cold regulated genes) transcript levels and cold-regulated metabolite levels prior to cold, after 2 week long cold acclimation and during the first 3 days of deacclimation. In the accessions with prolonged activation of cold responses, by trend, weaker induction of various cold-inducible PAS genes and stronger decreases in the expression of negatively cold-regulated PAS genes were observed. Low PAS gene expression delayed the post-cold decrease in H2O2 levels after transfer of the plants from cold to optimal growth conditions. We conclude that weaker expression of various PAS genes in the cold is an adapted strategy of the Arabidopsis accessions N14, N13, Ms-0, and Kas-1 to avoid full inactivation of cold-responses in the first days after the end of the cold period. PMID:27014325

  9. The Starburst-AGN connection: quenching the fire and feeding the monster

    NASA Astrophysics Data System (ADS)

    Melnick, Jorge; Telles, Eduardo; De Propris, Roberto; Chu, Zhang-Hu

    2015-10-01

    The merger of two spiral galaxies is believed to be one of the main channels for the production of elliptical and early-type galaxies. In the process, the system becomes an (ultra) luminous infrared galaxy, or (U)LIRG, that morphs to a quasar, to a K+A galaxy, and finally to an early-type galaxy. The time scales for this metamorphosis are only loosely constrained by observations. In particular, the K+A phase should follow immediately after the quasi stellar object (QSO) phase during which the dust and gas remaining from the (U)LIRG phase are expelled by the active galactic nucleus (AGN). An intermediate class of QSOs with K+A spectral signatures, the post-starburst QSOs (PSQ), may represent the transitional phase between QSOs and K+As. We have compiled a sample of 72 bona fide z < 0.5 PSQ from the SDSS DR7 QSO catalogue. We find the intermediate age populations in this sample to be on average significantly weaker and metal poorer than their putative descendants, the K+A galaxies. The typical spectral energy distribution of PSQ is well fitted by three components: starlight; an obscured power-law; and a hot dust component required to reproduce the mid-IR fluxes. From the slope and bolometric luminosity of the power-law component we estimate typical masses and accretion rates of the AGN, but we find little evidence of powerful radio-loud or strong X-ray emitters in our sample. This may indicate that the power-law component originates in a nuclear starburst rather than in an AGN, as expected if the bulk of their young stars are still being formed, or that the AGN is still heavily enshrouded in dust and gas. We find that both alternatives are problematic and that more and better optical, X-ray, and mm-wave observations are needed to elucidate the evolutionary history of PSQ.

  10. Electric Machines with Non-Radially Mounted Rectangular Permanent Magnets / Elektriskās Mašīnas Ar Prizmatiskiem Neradiāli Novietotiem Pastāvīgajiem Magnētiem

    NASA Astrophysics Data System (ADS)

    Levin, N.; Pugachev, V.; Dirba, J.; Lavrinovicha, L.

    2013-04-01

    The authors analyze the advantages and disadvantages of brushless synchronous electric machines with radially and non-radially mounted rectangular permanent magnets. The results show that the proposed nonradial mounting of permanent magnets considered in the paper, in several cases (e.g. multi-pole brushless generators with tooth windings of the armature) allows achievement of the following advantages: better technology of manufacturing the electric machine owing to simple packing of the stator winding in the stator open slots, which also increases the copper slot fillfactor; reduction in the mass-and-size of permanent magnets at least twice; significantly lower cost of the electric machine; and, finally, its greater specific power. Darbā tiek analizētas priekšrocības un trūkumi sinhronām bezkontaktu mašīnām ar radiāli un neradiāli novietotiem prizmatiskiem pastāvīgajiem magnētiem. Parādīts, ka vairākos gadījumos, piemēram, daudzpolu bezkontaktu sinhronajos ģeneratoros ar zobu tinumiem, neradiāls pastāvīgo magnētu izvietojums nodrošina vairākas priekšrocības: uzlabojas mašīnas izgatavošanas tehnoloģija, jo statora atvērtajās rievās vieglāk novietot tinumus un iespējams sasniegt augstāku rievas aizpildījuma koeficientu; samazinās pastāvīgo magnētu masa un izmaksas; palielinās mašīnas īpatnēja jauda.