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Sample records for bacterial reaction centers

  1. Electron transfer pathway analysis in bacterial photosynthetic reaction center

    CERN Document Server

    Kitoh-Nishioka, Hirotaka

    2016-01-01

    A new computational scheme to analyze electron transfer (ET) pathways in large biomolecules is presented with applications to ETs in bacterial photosynthetic reaction center. It consists of a linear combination of fragment molecular orbitals and an electron tunneling current analysis, which enables an efficient first-principles analysis of ET pathways in large biomolecules. The scheme has been applied to the ET from menaquinone to ubiquinone via nonheme iron complex in bacterial photosynthetic reaction center. It has revealed that not only the central Fe$^{2+}$ ion but also particular histidine ligands are involved in the ET pathways in such a way to mitigate perturbations that can be caused by metal ion substitution and depletion, which elucidates the experimentally observed insensitivity of the ET rate to these perturbations.

  2. Structure-function investigations of bacterial photosynthetic reaction centers.

    Science.gov (United States)

    Leonova, M M; Fufina, T Yu; Vasilieva, L G; Shuvalov, V A

    2011-12-01

    During photosynthesis light energy is converted into energy of chemical bonds through a series of electron and proton transfer reactions. Over the first ultrafast steps of photosynthesis that take place in the reaction center (RC) the quantum efficiency of the light energy transduction is nearly 100%. Compared to the plant and cyanobacterial photosystems, bacterial RCs are well studied and have relatively simple structure. Therefore they represent a useful model system both for manipulating of the electron transfer parameters to study detailed mechanisms of its separate steps as well as to investigate the common principles of the photosynthetic RC structure, function, and evolution. This review is focused on the research papers devoted to chemical and genetic modifications of the RCs of purple bacteria in order to study principles and mechanisms of their functioning. Investigations of the last two decades show that the maximal rates of the electron transfer reactions in the RC depend on a number of parameters. Chemical structure of the cofactors, distances between them, their relative orientation, and interactions to each other are of great importance for this process. By means of genetic and spectral methods, it was demonstrated that RC protein is also an essential factor affecting the efficiency of the photochemical charge separation. Finally, some of conservative water molecules found in RC not only contribute to stability of the protein structure, but are directly involved in the functioning of the complex.

  3. Conformational regulation of charge recombination reactions in a photosynthetic bacterial reaction center

    DEFF Research Database (Denmark)

    Katona, Gergely; Snijder, Arjan; Gourdon, Pontus Emanuel;

    2005-01-01

    In bright light the photosynthetic reaction center (RC) of Rhodobacter sphaeroides stabilizes the P(+)(870).Q(-)(A) charge-separated state and thereby minimizes the potentially harmful effects of light saturation. Using X-ray diffraction we report a conformational change that occurs within the cy...

  4. Ultrafast Electron Transfer Kinetics in the LM Dimer of Bacterial Photosynthetic Reaction Center from Rhodobacter sphaeroides.

    Science.gov (United States)

    Sun, Chang; Carey, Anne-Marie; Gao, Bing-Rong; Wraight, Colin A; Woodbury, Neal W; Lin, Su

    2016-06-23

    It has become increasingly clear that dynamics plays a major role in the function of many protein systems. One system that has proven particularly facile for studying the effects of dynamics on protein-mediated chemistry is the bacterial photosynthetic reaction center from Rhodobacter sphaeroides. Previous experimental and computational analysis have suggested that the dynamics of the protein matrix surrounding the primary quinone acceptor, QA, may be particularly important in electron transfer involving this cofactor. One can substantially increase the flexibility of this region by removing one of the reaction center subunits, the H-subunit. Even with this large change in structure, photoinduced electron transfer to the quinone still takes place. To evaluate the effect of H-subunit removal on electron transfer to QA, we have compared the kinetics of electron transfer and associated spectral evolution for the LM dimer with that of the intact reaction center complex on picosecond to millisecond time scales. The transient absorption spectra associated with all measured electron transfer reactions are similar, with the exception of a broadening in the QX transition and a blue-shift in the QY transition bands of the special pair of bacteriochlorophylls (P) in the LM dimer. The kinetics of the electron transfer reactions not involving quinones are unaffected. There is, however, a 4-fold decrease in the electron transfer rate from the reduced bacteriopheophytin to QA in the LM dimer compared to the intact reaction center and a similar decrease in the recombination rate of the resulting charge-separated state (P(+)QA(-)). These results are consistent with the concept that the removal of the H-subunit results in increased flexibility in the region around the quinone and an associated shift in the reorganization energy associated with charge separation and recombination. PMID:27243380

  5. Bacterial reaction centers purified with styrene maleic acid copolymer retain native membrane functional properties and display enhanced stability

    NARCIS (Netherlands)

    Swainsbury, David J K; Scheidelaar, Stefan; Van Grondelle, Rienk; Killian, J. Antoinette; Jones, Michael R.

    2014-01-01

    Integral membrane proteins often present daunting challenges for biophysical characterization, a fundamental issue being how to select a surfactant that will optimally preserve the individual structure and functional properties of a given membrane protein. Bacterial reaction centers offer a rare opp

  6. The protein's role in triplet energy transfer in bacterial reaction centers.

    Energy Technology Data Exchange (ETDEWEB)

    Laible, P. D.

    1998-08-14

    When photosynthetic organisms are subjected to high-light conditions in nature, electron transfer becomes blocked as the rate of conversion of light into charge-separated states in the reaction center (RC) exceeds the capacity of the soluble carriers involved in cyclic electron transfer. In that event, a well-characterized T{sub 0}-polarized triplet state {sup T}P, is formed on the primary donor, P, from the P{sup +}H{sub A}{sup {minus}} state (reviewed in [1]). In an aerobic or semi-aerobic environment, the major role of the carotenoid (C), also bound by the RC, is to quench {sup T}P prior to its sensitization of the {sup 1}{Delta}{sub g} singlet state of oxygen--a potentially damaging biological oxidant. The carotenoid performs this function efficiently in most bacterial RCs by rapidly accepting the triplet state from P and dissipating this excited-state energy into heat through internal conversion. The lowest-lying triplet states of P and the carotenoid are sufficiently different that {sup T}P can promote oxygen to its excited singlet state whereas {sup T}C can quench the {sup T}P state (reviewed in [2]).

  7. Photocurrent Generation by Photosynthetic Purple Bacterial Reaction Centers Interfaced with a Porous Antimony-Doped Tin Oxide (ATO) Electrode.

    Science.gov (United States)

    Carey, Anne-Marie; Zhang, HaoJie; Mieritz, Daniel; Volosin, Alex; Gardiner, Alastair T; Cogdell, Richard J; Yan, Hao; Seo, Dong-Kyun; Lin, Su; Woodbury, Neal W

    2016-09-28

    The ability to exchange energy and information between biological and electronic materials is critical in the development of hybrid electronic systems in biomedicine, environmental sensing, and energy applications. While sensor technology has been extensively developed to collect detailed molecular information, less work has been done on systems that can specifically modulate the chemistry of the environment with temporal and spatial control. The bacterial photosynthetic reaction center represents an ideal photonic component of such a system in that it is capable of modifying local chemistry via light-driven redox reactions with quantitative control over reaction rates and has inherent spectroscopic probes for monitoring function. Here a well-characterized model system is presented, consisting of a transparent, porous electrode (antimony-doped tin oxide) which is electrochemically coupled to the reaction center via a cytochrome c molecule. Upon illumination, the reaction center performs the 2-step, 2-electron reduction of a ubiquinone derivative which exchanges with oxidized quinone in solution. Electrons from the electrode then move through the cytochrome to reoxidize the reaction center electron donor. The result is a facile platform for performing redox chemistry that can be optically and electronically controlled in time and space.

  8. Charge recombination kinetics and protein dynamics in wild type and carotenoid-less bacterial reaction centers: studies in trehalose glasses.

    Science.gov (United States)

    Francia, Francesco; Malferrari, Marco; Sacquin-Mora, Sophie; Venturoli, Giovanni

    2009-07-30

    The coupling between electron transfer and protein dynamics has been investigated in reaction centers (RCs) from the wild type (wt) and the carotenoid-less strain R26 of the photosynthetic bacterium Rhodobacter sphaeroides. Recombination kinetics between the primary photoreduced quinone acceptor (QA-) and photoxidized donor (P+) have been analyzed at room temperature in RCs incorporated into glassy trehalose matrices of different water/sugar ratios. As previously found in R26 RCs, also in the wt RC, upon matrix dehydration, P+QA- recombination accelerates and becomes broadly distributed, reflecting the inhibition of protein relaxation from the dark-adapted to the light-adapted conformation and the hindrance of interconversion between conformational substates. While in wet trehalose matrices (down to approximately one water per trehalose molecule) P+QA- recombination kinetics are essentially coincident in wt and R26 RCs, more extensive dehydration leads to two-times faster and more distributed kinetics in the carotenoid-containing RC, indicating a stronger inhibition of the internal protein dynamics in the wt RC. Coarse-grained Brownian dynamics simulations performed on the two RC structures reveal a markedly larger flexibility of the R26 RC, showing that a rigid core of residues, close to the quinone acceptors, is specifically softened in the absence of the carotenoid. These experimental and computational results concur to indicate that removal of the carotenoid molecule has long-range effects on protein dynamics and that the structural/dynamical coupling between the protein and the glassy matrix depends strongly upon the local mechanical properties of the protein interior. The data also suggest that the conformational change stabilizing P+QA- is localized around the QA binding pocket.

  9. Elastic Vibrations in the Photosynthetic Bacterial Reaction Center Coupled to the Primary Charge Separation: Implications from Molecular Dynamics Simulations and Stochastic Langevin Approach.

    Science.gov (United States)

    Milanovsky, Georgy E; Shuvalov, Vladimir A; Semenov, Alexey Yu; Cherepanov, Dmitry A

    2015-10-29

    Primary electron transfer reactions in the bacterial reaction center are difficult for theoretical explication: the reaction kinetics, almost unalterable over a wide range of temperature and free energy changes, revealed oscillatory features observed initially by Shuvalov and coauthors (1997, 2002). Here the reaction mechanism was studied by molecular dynamics and analyzed within a phenomenological Langevin approach. The spectral function of polarization around the bacteriochlorophyll special pair PLPM and the dielectric response upon the formation of PL(+)PM(-) dipole within the special pair were calculated. The system response was approximated by Langevin oscillators; the respective frequencies, friction, and energy coupling coefficients were determined. The protein dynamics around PL and PM were distinctly asymmetric. The polarization around PL included slow modes with the frequency 30-80 cm(-1) and the total amplitude of 130 mV. Two main low-frequency modes of protein response around PM had frequencies of 95 and 155 cm(-1) and the total amplitude of 30 mV. In addition, a slowly damping mode with the frequency of 118 cm(-1) and the damping time >1.1 ps was coupled to the formation of PL(+)PM(-) dipole. It was attributed to elastic vibrations of α-helices in the vicinity of PLPM. The proposed trapping of P excitation energy in the form of the elastic vibrations can rationalize the observed properties of the primary electron transfer reactions, namely, the unusual temperature and ΔG dependences, the oscillating phenomena in kinetics, and the asymmetry of the charge separation reactions. PMID:26148224

  10. Program PROTEUS for adding hydrogens to a protein structure and electrostatic field across carotenoids in light harvesting complexes and reaction centers from bacterial sources

    Science.gov (United States)

    Lipovaca, Samir

    The hydrogen construction method presented in the program PROTEUS treats hydrogens depending on their torsional degrees of freedom. The positions of hydrogens with restricted torsional degrees of freedom are completely determined by the heavy atoms positions in the structure. The hydroxyl and water hydrogens are the only hydrogens that PROTEUS accepts as movable hydrogens (having rotational degrees of freedom). Their positions are determined by the interactions with neighboring atoms. PROTEUS interaction energy corresponds to a view that the hydrogen bond is affected, besides electrostatic effects and steric constraints of neighboring groups, by an inherent energy barrier that opposes free rotation of the hydroxyl hydrogen. For the water hydrogens that barrier is zero. The hydroxyl and water hydrogens are minimized within a short distance using the Threshold Accepting (TA) energy minimization method. PROTEUS can provide reasonable positions of movable hydrogens and a good initial protein structure for further investigations. We applied the program PROTEUS to place hydrogens in several resolved three-dimensional crystal structures of light harvesting complexes (LHCs) and reaction centers (RCs) from bacterial sources. Using program DelPhi we calculated the local electrostatic field across carotenoid generated by the protein's charges. In each structure we identified amino acids responsible for the field. Much of the field is generated by the charged residues. There are different ways that a RC or LHC uses charged residues. A nearby dipole consisting of the charged residues which are ionized in the physiological pH range (like Arg-Asp), is often used. Clusters of charged residues or scattered isolated charged residues around the carotenoid molecule also contribute. The polarizable field is not necessarily along the carotenoid molecule principal axis. For soluble LHCs the contribution of polar residues to the field cannot be neglected. Our calculations indicate an

  11. Kinetics of H+ ion binding by the P+QA-state of bacterial photosynthetic reaction centers: rate limitation within the protein.

    Science.gov (United States)

    Maróti, P; Wraight, C A

    1997-01-01

    The kinetics of flash-induced H+ ion binding by isolated reaction centers (RCs) of Rhodobacter sphaeroides, strain R-26, were measured, using pH indicators and conductimetry, in the presence of terbutryn to block electron transfer between the primary and secondary quinones (QA and QB), and in the absence of exogenous electron donors to the oxidized primary donor, P+, i.e., the P+QA-state. Under these conditions, proton binding by RCs is to the protein rather than to any of the cofactors. After light activation to form P+QA-, the kinetics of proton binding were monoexponential at all pH values studied. At neutral pH, the apparent bimolecular rate constant was close to the diffusional limit for proton transfer in aqueous solution (approximately 10(11) M-1 s-1), but increased significantly in the alkaline pH range (e.g., 2 x 10(13) M-1 s-1 at pH 10). The average slope of the pH dependence was -0.4 instead of -1.0, as might be expected for a H+ diffusion-controlled process. High activation energy (0.54 eV at pH 8.0) and weak viscosity dependence showed that H+ ion uptake by RCs is not limited by diffusion. The salt dependence of the H+ ion binding rate and the pK values of the protonatable amino acid residues of the reaction center implicated surface charge influences, and Gouy-Chapman theory provided a workable description of the ionic effects as arising from modulation of the pH at the surface of the RC. Incubation in D2O caused small increases in the pKs of the protonatable groups and a small, pH (pD)-dependent slowing of the binding rate. The salt, pH, temperature, viscosity, and D2O dependences of the proton uptake by RCs in the P+QA- state were accounted for by three considerations: 1) parallel pathways of H+ delivery to the RC, contributing to the observed (net) H+ disappearance; 2) rate limitation of the protonation of target groups within the protein by conformational dynamics; and 3) electrostatic influences of charged groups in the protein, via the surface p

  12. Kinetics of H+ ion binding by the P+QA-state of bacterial photosynthetic reaction centers: rate limitation within the protein.

    Science.gov (United States)

    Maróti, P; Wraight, C A

    1997-07-01

    The kinetics of flash-induced H+ ion binding by isolated reaction centers (RCs) of Rhodobacter sphaeroides, strain R-26, were measured, using pH indicators and conductimetry, in the presence of terbutryn to block electron transfer between the primary and secondary quinones (QA and QB), and in the absence of exogenous electron donors to the oxidized primary donor, P+, i.e., the P+QA-state. Under these conditions, proton binding by RCs is to the protein rather than to any of the cofactors. After light activation to form P+QA-, the kinetics of proton binding were monoexponential at all pH values studied. At neutral pH, the apparent bimolecular rate constant was close to the diffusional limit for proton transfer in aqueous solution (approximately 10(11) M-1 s-1), but increased significantly in the alkaline pH range (e.g., 2 x 10(13) M-1 s-1 at pH 10). The average slope of the pH dependence was -0.4 instead of -1.0, as might be expected for a H+ diffusion-controlled process. High activation energy (0.54 eV at pH 8.0) and weak viscosity dependence showed that H+ ion uptake by RCs is not limited by diffusion. The salt dependence of the H+ ion binding rate and the pK values of the protonatable amino acid residues of the reaction center implicated surface charge influences, and Gouy-Chapman theory provided a workable description of the ionic effects as arising from modulation of the pH at the surface of the RC. Incubation in D2O caused small increases in the pKs of the protonatable groups and a small, pH (pD)-dependent slowing of the binding rate. The salt, pH, temperature, viscosity, and D2O dependences of the proton uptake by RCs in the P+QA- state were accounted for by three considerations: 1) parallel pathways of H+ delivery to the RC, contributing to the observed (net) H+ disappearance; 2) rate limitation of the protonation of target groups within the protein by conformational dynamics; and 3) electrostatic influences of charged groups in the protein, via the surface pH.

  13. The nature of the lower excited state of the special pair of bacterial photosynthetic reaction center of Rhodobacter Sphaeroides and the dynamics of primary charge separation

    Science.gov (United States)

    Ivashin, N. V.; Shchupak, E. E.

    2016-08-01

    Quantum-chemical calculations of the structure in the ground and lower singlet excited states and the vibrations (in the ground state) of special pair P of photosynthetic reaction center of purple bacteria (RCPb) Rhodobacter Sphaeroides, consisting of two bacteriochlorophyll molecules PA and PB, have been carried out. It is shown that excitation of the special pair is followed by fast relaxation dynamics, accompanied by the transformation of the initial P* state into the P A δ+ P B δ- state (δ ~ 0.5) with charge separation. This behavior is due to the presence of several nonplanar vibrations with participation of the acetyl group of macrocycle PB in the nuclear wave packet on the potential surface of the P* state; these vibrations facilitate destabilization of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of the macrocycle PA and formation of the P A δ+ P B δ- state. The structural transformations in the P* state are due to its linking character in the contact region of the acetyl group-containing pyrrole rings of PA and PB. The transition from the P* state to specifically the P A δ+ P B δ- state is related to the fact that the acetyl group PA is involved in the intermolecular hydrogen bond with amino acid residue HisL168; for this reason, this group and the pyrrole ring linked with it can hardly participate in structural transformations. The electronic matrix element H12 of the electron transfer from the special pair in the P A δ+ P B δ- state to a molecule of accessory bacteriochlorophyll BA greatly exceeds that for the transfer to BB. This circumstance and the fact that the P A δ+ P B δ- state is energetically more favorable than the P* state facilitate the preferred directionality of the electron transfer in RCPb Rhodobacter Sphaeroides with participation of the cofactors located in its subunit L.

  14. The mechanism of electronic excitation in the bacterial bioluminescent reaction

    International Nuclear Information System (INIS)

    The current state of the problem of formation of the electron-excited product in the chemiluminescent reaction that underlies the bacterial luminescence is analysed. Various schemes of chemical transformations capable of producing a bacterial bioluminescence emitter are presented. The problem of excitation of secondary emitters is considered; two possible mechanisms of their excitation are analysed.

  15. Protein-lipid interactions in the purple bacterial reaction centre.

    Science.gov (United States)

    Jones, Michael R; Fyfe, Paul K; Roszak, Aleksander W; Isaacs, Neil W; Cogdell, Richard J

    2002-10-11

    The purple bacterial reaction centre uses the energy of sunlight to power energy-requiring reactions such as the synthesis of ATP. During the last 20 years, a combination of X-ray crystallography, spectroscopy and mutagenesis has provided a detailed insight into the mechanism of light energy transduction in the bacterial reaction centre. In recent years, structural techniques including X-ray crystallography and neutron scattering have also been used to examine the environment of the reaction centre. This mini-review focuses on recent studies of the surface of the reaction centre, and briefly discusses the importance of the specific protein-lipid interactions that have been resolved for integral membrane proteins.

  16. Mechanical reaction-diffusion model for bacterial population dynamics

    CERN Document Server

    Ngamsaad, Waipot

    2015-01-01

    The effect of mechanical interaction between cells on the spreading of bacterial population was investigated in one-dimensional space. A nonlinear reaction-diffusion equation has been formulated as a model for this dynamics. In this model, the bacterial cells are treated as the rod-like particles that interact, when contacting each other, through the hard-core repulsion. The repulsion introduces the exclusion process that causes the fast diffusion in bacterial population at high density. The propagation of the bacterial density as the traveling wave front in long time behavior has been analyzed. The analytical result reveals that the front speed is enhanced by the exclusion process---and its value depends on the packing fraction of cell. The numerical solutions of the model have been solved to confirm this prediction.

  17. Bacterial and Archaeal Diversity From the Eastern Lau Spreading Center

    Science.gov (United States)

    Reysenbach, A.; Banta, A.; Kelly, S.; Kirshstein, J.; Voytek, M.

    2005-12-01

    Due to the diversity of venting styles, geological settings and variations in fluid geochemistry, the Valu Fa Ridge and Eastern Lau Spreading Center (ELSC) provide a unique opportunity to explore the effects geological and geochemical variables on patterns of microbial phylogenetic and metabolic diversity. High temperature sulfides, diffuse flow fluids and microbial mats were collected from six active vent fields on the Valu Fa Ridge and Eastern Lau Spreading Center during the R/V Melville cruise TUIM05MV. All samples were subsampled for molecular and microbial culturing purposes. The archaeal and bacterial 16S rRNA genes were amplified by PCR from a selection of samples. Additionally, the presence of Aquificales and an unidentified lineage, the DHVE archaeal group, was explored using PCR primers specific for these groups. A selection of DNAs were also screened for functional genes that are diagnostic for certain pathways, viz, aclB (reductive TCA cycle), mcrA (methanogenesis), nirS and nirK (nitrite reduction), amoA (ammonia oxidation). Culturing of thermophiles, both acidophiles and neutrophiles, was initiated. Over 20 hydrogen oxidizing (hydrogen and oxygen) or nitrate reducing (hydrogen and nitrate) chemolithoautotrophs were isolated as colonies and grow at 70 degrees C. All are related to Persephonella hydrogenophila, with the exception of 2 cultures that perhaps represent new species of Hydrogenivirga and Aquifex. Preliminary analysis of patterns of Aquificales diversity using both culturing and molecular approaches suggest that the distributions of this group alone are very different from that observed at other hydrothermal sites such as along the East Pacific Rise or Central Indian Ridge. As yet, the most commonly isolated Aquificales, P. marina, has not been detected in enrichment cultures from ELSC, and the diversity of Aquificales-related sequences is much greater than detected from sites along the EPR. It is therefore also likely, that patterns of

  18. Influence of pigment substitution on the electrochemical properties of Rhodobacter sphaeroides 601 reaction centers

    Institute of Scientific and Technical Information of China (English)

    邹永龙; 赵杰权; 陈志龙; 孔继烈; 曾小华; 徐春和

    2001-01-01

    With the help of pigment substitution, self-assembled monolayer film and square wave voltammetry, the influence of pigment substitution on the electrochemical properties of Rhodobacter sphaeroides 601 reaction centers was investigated. Results showed that the charge separation could also be driven by externally electric field, similar to the primary photochemical reaction in purple bacterial reaction center. On the surface of Au electrode, a self-assembled monolayer film (the RC-PDDA-DMSA film) was made up of 2,3-dimercaptosuccinic acid (DMSA), poly-dimeth-yldiallylammonium chloride (PDDA) and reaction center (RC). When square wave voltammetry was used to study the RC-PDDA-DMSA film, four redox pairs in the photochemical reaction of RC were observed by changing frequency. With nonlinear fitting, the standard potential of P/P+ and the corresponding electrode reaction rate constant were determined to be 0.522 V and 13.04 S-1, respectively. It was found that the redox peak at -0.02 V changed greatly when bacteriopheophytin was substituted by plant pheophytin in the reaction center. Further studies indicated that this change resulted from the decrease in electron transfer rate between Bphe-/Bphe (Phe-/Phe) and QA-/QA after pigment substitution. After investigations of spectra and electrochemical properties of different RCs and comparisons of different function groups of pigments, it was indicated that the phytyl tail, similar to other substituted groups of pheophytin, affected the efficiencies of pigment substitution.

  19. Observation of Coherence in the Photosystem II Reaction Center

    CERN Document Server

    Fuller, Franklin D; Senlik, S Seckin; Wilcox, Daniel E; Ogilvie, Jennifer P

    2013-01-01

    Photosynthesis powers life on our planet. The basic photosynthetic architecture comprises antenna complexes to harvest solar energy and reaction centers to convert the energy into a stable charge separated state. In oxygenic photosynthesis, the initial charge separation event occurs in the photosystem II reaction center; the only known natural enzyme that uses solar energy to split water. Energy transfer and charge separation in photosynthesis are rapid and have high quantum efficiencies. Recently, nonlinear spectroscopic experiments have suggested that electronic coherence may play a role in energy transfer efficiency in antenna complexes. Here we report the observation of coherence in the photosystem II reaction center by two dimensional electronic spectroscopy. The frequencies of the observed coherences match exciton difference frequencies and/or known vibrational modes of the photosystem II reaction center. These observations raise questions about the possible role of electronic and/or vibrational coheren...

  20. Influence of pigment substitution on the electrochemical properties of Rhodobacter sphaeroides 601 reaction centers

    Institute of Scientific and Technical Information of China (English)

    ZOU; YOnglong(

    2001-01-01

    [1]Deisenhofer. J., Epp, O.. Miki, K. et al., Structure of the protein subunits in the photosynthetic reaction center of Rhodopseudomonas viridis at 3A resolution, Nature, 1985, 318: 618-624.[2]Marcus, R. A., Election transfer reaction in chemistry: Theory and experiment (Nobel lecture), Angewandte Chemie, 1993,32: 1111-1121.[3]Woodbury, N. W., Becker, M., Middendorf, D. et al., Picosecond kinetics of the initial photochemical electron-transfer reaction in bacterial photosynthetic reaction centers, Biochemistry, 1985, 24 (26): 7516-7521.[4]Scheer, H., Struck, A., Bacterial reaction centers with modified tetrapyrrole chromophores, in The Photosynthetic Reaction Center (Ⅰ) (eds. Deisenhofer, J., Norris, J.), San Diego: Academic Press, 1993, 157-192.[5]Meyer, M., Scheer, H., Reaction centers of Rhodobacter sphaeroides R26 containing C-3 acetyl and vinyl (bacterio)pheophytines at sites HA,B, Photosynth. Res., 1995, 44: 55-65.[6]Schmidt, S., Arlt, T., Hamm, P. et al., Energetics of the primary electron transfer reaction revealed by ultrafast spectroscopy on modified bacterial reaction centers, Chem. Phys. Lett., 1994, 223: 116-120.[7]Kennis, J. T. M., Shkuropatov, A. Y., Van Stokkum, I. H. M. et al., Formation of a long-lived P+BA- state in plant pheophytin-exchanged reaction centers of Rhodobacter sphaeroides R26 at low temperature, Biochemistry, 1997, 36:16231-16238.[8]Tasayco, M. L., Carey, J., Ordered self-assembly of polypeptide fragments to form native like dimeric trp repressor, Science. 1992, 255: 594-597.[9]Kong, J. L., Lu, Z. Q., Lvov, Y. M. et al., Direct electrochemistry of cofactor redox sites in a bacterial photosynthetic reaction center protein, J. Am. Chem. Soc., 1998, 120 (29): 7371-7372.[10]Nassar, A. E. F., Bobbitt, J. M., Stuart, J. M. et al., Catalytic reduction of organohalide pollutants by myoglobin in a biomembrane-like surfactant film, J. Am. Chem. Soc., 1995, 117: 10986-10993.[11]Zeng, X. H., Wu, Y

  1. Artificial photosynthetic reaction centers coupled to light-harvesting antennas.

    Science.gov (United States)

    Ghosh, Pulak Kumar; Smirnov, Anatoly Yu; Nori, Franco

    2011-12-01

    We analyze a theoretical model for energy and electron transfer in an artificial photosynthetic system. The photosystem consists of a molecular triad (i.e., with a donor, a photosensitive unit, and an acceptor) coupled to four accessory light-harvesting-antenna pigments. The resonant energy transfer from the antennas to the artificial reaction center (the molecular triad) is described here by the Förster mechanism. We consider two different kinds of arrangements of the accessory light-harvesting pigments around the reaction center. The first arrangement allows direct excitation transfer to the reaction center from all the surrounding pigments. The second configuration transmits energy via a cascade mechanism along a chain of light-harvesting chromophores, where only one chromophore is connected to the reaction center. We show that the artificial photosynthetic system using the cascade energy transfer absorbs photons in a broader wavelength range and converts their energy into electricity with a higher efficiency than the system based on direct couplings between all the antenna chromophores and the reaction center.

  2. Bio-Photoelectrochemical Solar Cells Incorporating Reaction Center and Reaction Center Plus Light Harvesting Complexes

    Science.gov (United States)

    Yaghoubi, Houman

    Harvesting solar energy can potentially be a promising solution to the energy crisis now and in the future. However, material and processing costs continue to be the most important limitations for the commercial devices. A key solution to these problems might lie within the development of bio-hybrid solar cells that seeks to mimic photosynthesis to harvest solar energy and to take advantage of the low material costs, negative carbon footprint, and material abundance. The bio-photoelectrochemical cell technologies exploit biomimetic means of energy conversion by utilizing plant-derived photosystems which can be inexpensive and ultimately the most sustainable alternative. Plants and photosynthetic bacteria harvest light, through special proteins called reaction centers (RCs), with high efficiency and convert it into electrochemical energy. In theory, photosynthetic RCs can be used in a device to harvest solar energy and generate 1.1 V open circuit voltage and ~1 mA cm-2 short circuit photocurrent. Considering the nearly perfect quantum yield of photo-induced charge separation, efficiency of a protein-based solar cell might exceed 20%. In practice, the efficiency of fabricated devices has been limited mainly due to the challenges in the electron transfer between the protein complex and the device electrodes as well as limited light absorption. The overarching goal of this work is to increase the power conversion efficiency in protein-based solar cells by addressing those issues (i.e. electron transfer and light absorption). This work presents several approaches to increase the charge transfer rate between the photosynthetic RC and underlying electrode as well as increasing the light absorption to eventually enhance the external quantum efficiency (EQE) of bio-hybrid solar cells. The first approach is to decrease the electron transfer distance between one of the redox active sites in the RC and the underlying electrode by direct attachment of the of protein complex

  3. Recycling probability and dynamical properties of germinal center reactions

    CERN Document Server

    Meyer-Hermann, M; Or-Guil, M; Meyer-Hermann, Michael; Deutsch, Andreas; Or-Guil, Michal

    2001-01-01

    We introduce a new model for the dynamics of centroblasts and centrocytes in a germinal center. The model reduces the germinal center reaction to the elements considered as essential and embeds proliferation of centroblasts, point mutations of the corresponding antibody types represented in a shape space, differentiation to centrocytes, selection with respect to initial antigens, differentiation of positively selected centrocytes to plasma or memory cells and recycling of centrocytes to centroblasts. We use exclusively parameters with a direct biological interpretation such that, once determined by experimental data, the model gains predictive power. Based on the experiment of Han et al.(1995) we predict that a high rate of recycling of centrocytes to centroblasts is necessary for the germinal center reaction to work reliably. Furthermore, we find a delayed start of the production of plasma and memory cells with respect to the start of point mutations, which turns to be necessary for the optimization process ...

  4. Quantum delocalization directs antenna absorption to photosynthetic reaction centers

    OpenAIRE

    Caycedo-Soler, Felipe; Schroeder, Chris A.; Autenrieth, Caroline; Ghosh, Robin; Huelga, Susana F.; Plenio, Martin B.

    2015-01-01

    Photosynthesis -- the conversion of sunlight to chemical energy -- is fundamental for supporting life on our planet. Despite its importance, the physical principles that underpin the primary steps of photosynthesis, from photon absorption to electronic charge separation, remain to be understood in full. Previously, electronic coherence within tightly-packed light-harvesting (LH) units or within individual reaction centers (RCs) has been recognized as an important ingredient for a complete und...

  5. Diversity of Bacterial Communities of Fitness Center Surfaces in a U.S. Metropolitan Area

    Directory of Open Access Journals (Sweden)

    Nabanita Mukherjee

    2014-12-01

    Full Text Available Public fitness centers and exercise facilities have been implicated as possible sources for transmitting community-acquired bacterial infections. However, the overall diversity of the bacterial community residing on the surfaces in these indoor environments is still unknown. In this study, we investigated the overall bacterial ecology of selected fitness centers in a metropolitan area (Memphis, TN, USA utilizing culture-independent pyrosequencing of the 16S rRNA genes. Samples were collected from the skin-contact surfaces (e.g., exercise instruments, floor mats, handrails, etc. within fitness centers. Taxonomical composition revealed the abundance of Firmicutes phyla, followed by Proteobacter and Actinobacteria, with a total of 17 bacterial families and 25 bacterial genera. Most of these bacterial genera are of human and environmental origin (including, air, dust, soil, and water. Additionally, we found the presence of some pathogenic or potential pathogenic bacterial genera including Salmonella, Staphylococcus, Klebsiella, and Micrococcus. Staphylococcus was found to be the most prevalent genus. Presence of viable forms of these pathogens elevates risk of exposure of any susceptible individuals. Several factors (including personal hygiene, surface cleaning and disinfection schedules of the facilities may be the reasons for the rich bacterial diversity found in this study. The current finding underscores the need to increase public awareness on the importance of personal hygiene and sanitation for public gym users.

  6. A Photovoltaic Device Using an Electrolyte Containing Photosynthetic Reaction Centers

    Energy Technology Data Exchange (ETDEWEB)

    Takshi, Arash [Dept. of Electrical Engineering, Univ. of South Florida (USF), Tampa, FL (United States); Madden, John D.W. [Dept. of Electrical and Computer Engineering, Advanced Materials and Process Engineering Lab., and Dept. of Microbiology and Immunology, Univ. of British Columbia (UBC), Vancouver BC (Canada); Mahmoudzadeh, Ali [Dept. of Electrical and Computer Engineering, Advanced Materials and Process Engineering Lab., and Dept. of Microbiology and Immunology, Univ. of British Columbia (UBC), Vancouver BC (Canada); Saer, Rafael [Dept. of Electrical and Computer Engineering, Advanced Materials and Process Engineering Lab., and Dept. of Microbiology and Immunology, Univ. of British Columbia (UBC), Vancouver BC (Canada); Beatty, J. Thomas [Dept. of Microbiology and Immunology, Univ. of British Columbia (UBC), Vancouver BC (Canada)

    2010-10-15

    The performance of bio-photovoltaic devices with a monolayer of the immobilized photosynthetic reaction center (RC) is generally low because of weak light absorption and poor charge transfer between the RC and the electrode. In this paper, a new bio-photovoltaic device is described in which the RC is dissolved in the electrolyte of an electrochemical cell. The charges generated by the illuminated RC are transferred to electrodes via mediators. The difference between the reaction rates of two types of mediator at the electrode surfaces determines the direction of the photocurrent in the device. Experimental results show that the magnitude of the photocurrent is proportional to the incident light intensity, and the current increases nonlinearly with an increase in the RC concentration in the electrolyte. With further optimization this approach should lead to devices with improved light absorption.

  7. A multi-pathway model for photosynthetic reaction center

    Science.gov (United States)

    Qin, M.; Shen, H. Z.; Yi, X. X.

    2016-03-01

    Charge separation occurs in a pair of tightly coupled chlorophylls at the heart of photosynthetic reaction centers of both plants and bacteria. Recently it has been shown that quantum coherence can, in principle, enhance the efficiency of a solar cell, working like a quantum heat engine. Here, we propose a biological quantum heat engine (BQHE) motivated by Photosystem II reaction center (PSII RC) to describe the charge separation. Our model mainly considers two charge-separation pathways which is more than that typically considered in the published literature. We explore how these cross-couplings increase the current and power of the charge separation and discuss the effects of multiple pathways in terms of current and power. The robustness of the BQHE against the charge recombination in natural PSII RC and dephasing induced by environments is also explored, and extension from two pathways to multiple pathways is made. These results suggest that noise-induced quantum coherence helps to suppress the influence of acceptor-to-donor charge recombination, and besides, nature-mimicking architectures with engineered multiple pathways for charge separations might be better for artificial solar energy devices considering the influence of environments.

  8. A multi-pathway model for Photosynthetic reaction center

    CERN Document Server

    Qin, M; Yi, X X

    2015-01-01

    Charge separation in light-harvesting complexes occurs in a pair of tightly coupled chlorophylls at the heart of photosynthetic reaction centers of both plants and bacteria. Recently it has been shown that quantum coherence can, in principle, enhance the efficiency of a solar cell, working like a quantum heat engine (QHE). Here, we propose a biological quantum heat engine (BQHE) motivated by Photosystem {\\rm II} reaction center (PS{\\rm II} RC) to describe the charge separation. Our model mainly considers two charge-separation pathways more than that in the published literature. The two pathways can interfere via cross-couplings and work together to enhance the charge-separation yields. We explore how these cross-couplings increase the current and voltage of the charge separation and discuss the advantages of multiple pathways in terms of current and power. The robustness of the BQHE against the charge recombination in natural PS{\\rm II} RC and dephasing induced by environments is also explored, and extension ...

  9. Quantum delocalization directs antenna absorption to photosynthetic reaction centers

    CERN Document Server

    Caycedo-Soler, Felipe; Autenrieth, Caroline; Ghosh, Robin; Huelga, Susana F; Plenio, Martin B

    2015-01-01

    Photosynthesis -- the conversion of sunlight to chemical energy -- is fundamental for supporting life on our planet. Despite its importance, the physical principles that underpin the primary steps of photosynthesis, from photon absorption to electronic charge separation, remain to be understood in full. Previously, electronic coherence within tightly-packed light-harvesting (LH) units or within individual reaction centers (RCs) has been recognized as an important ingredient for a complete understanding of the excitation energy transfer dynamics. However, the electronic coherence across RC and LH units has been consistently neglected as it does not play a significant role during these relatively slow transfer processes. Here, we turn our attention to the absorption process, which occurs on much shorter timescales. We demonstrate that the - often overlooked - spatially extended but short-lived excitonic delocalization across RC and LH units plays a relevant role in general photosynthetic systems, as it causes a...

  10. The type of seeder cells determines the efficiency of germinal center reactions

    CERN Document Server

    Meyer-Hermann, M; Meyer-Hermann, Michael; Beyer, Tilo

    2002-01-01

    We discuss the origin of two classes of germinal centers that have been observed during humoral immune responses: Some germinal centers develop very well and give rise to a large number of high affinity antibody producing plasma cells. Other germinal center reaction are very weak and the output production is practically absent. We propose an explanation for this nearly all-or-none behavior of germinal center reactions: The affinity of the seeder B-cells to the antigen is the critical parameter that determines the fate of the germinal center reaction. This hypothesis is verified in the framework of a space-time simulation of germinal center reactions.

  11. Regulation of Germinal Center Reactions by B and T Cells

    Directory of Open Access Journals (Sweden)

    Yeonseok Chung

    2013-10-01

    Full Text Available Break of B cell tolerance to self-antigens results in the development of autoantibodies and, thus, leads to autoimmunity. How B cell tolerance is maintained during active germinal center (GC reactions is yet to be fully understood. Recent advances revealed several subsets of T cells and B cells that can positively or negatively regulate GC B cell responses in vivo. IL-21-producing CXCR5+ CD4+ T cells comprise a distinct lineage of helper T cells—termed follicular helper T cells (TFH—that can provide help for the development of GC reactions where somatic hypermutation and affinity maturation take place. Although the function of TFH cells is beneficial in generating high affinity antibodies against infectious agents, aberrant activation of TFH cell or B cell to self-antigens results in autoimmunity. At least three subsets of immune cells have been proposed as regulatory cells that can limit such antibody-mediated autoimmunity, including follicular regulatory T cells (TFR, Qa-1 restricted CD8+ regulatory T cells (CD8+TREG, and regulatory B cells (BREG. In this review, we will discuss our current understanding of GC B cell regulation with specific emphasis on the newly identified immune cell subsets involved in this process.

  12. Bacterial Bioluminescence: Spectral Study of the Emitters in the In Vivo Reaction

    NARCIS (Netherlands)

    Matheson, I.B.C.; Lee, J.; Muller, F.

    1981-01-01

    Transient fluorescent species are observed in the bioluminescent reactions of three reduced flavin mononucleotides with aliphatic aldehydes and oxygen, catalyzed by bacterial luciferase. In each case the fluorescence spectral distribution is similar to that of the bioluminescence but is readily dist

  13. The utility of the polymerase chain reaction assay for aetiologic definition of unspecified bacterial meningitis cases

    Directory of Open Access Journals (Sweden)

    Mari Tuyama

    2008-03-01

    Full Text Available Most patients with acute suppurative meningitis are otherwise healthy individuals with regard to immune mechanisms against invasive bacterial disease. This medical emergency is among the most dramatic and potentially ravaging diseases that affect humans, particularly young children. The illness often strikes suddenly, and can either result in death or leave the survivors with significant neurological dysfunctions. The demonstration of a bacterial aetiology is necessary for decisions regarding treatment and prophylaxis. Conventional bacteriological methods frequently fail to identify an agent, as a result of administration of antibiotics or delayed lumbar punctures. We investigated the major aetiologic sources of unspecified bacterial meningitis cases (G00.9, ISCD-10 by polymerase chain reaction (PCR-based identification of Neisseria meningitidis (crgA, Streptococcus pneumoniae (ply and Haemophilus influenzae (bexA in cerebrospinal fluid samples. The multiplex PCR detected N. meningitidis in 92%, S. pneumoniae in 4% and H. influenzae in 1% of the 192 clinical samples assayed; 3% were negative for all three DNA targets. Bacterial DNA detection was found to be a valuable adjunct to enhance bacterial meningitis surveillance when the yield of specimens by culture is reduced. The implementation of PCR assays as a diagnostic procedure in Public Health Laboratories is perceived to be a significant advance in the investigation of bacterial meningitis.

  14. Diffusion model for charge transfer from a photosynthetic reaction center to an electrode in a photovoltaic device

    Energy Technology Data Exchange (ETDEWEB)

    Takshi, Arash [Department of Microbiology and Immunology, University of British Columbia (UBC), Vancouver, BC V6T 1Z3 (Canada); Department of Electrical and Computer Engineering and Advanced Materials and Process Engineering Lab, University of British Columbia (UBC), Vancouver, BC V6T 1Z1 (Canada)], E-mail: arasht@ece.ubc.ca; Madden, John D. [Department of Electrical and Computer Engineering and Advanced Materials and Process Engineering Lab, University of British Columbia (UBC), Vancouver, BC V6T 1Z1 (Canada); Beatty, J. Thomas [Department of Microbiology and Immunology, University of British Columbia (UBC), Vancouver, BC V6T 1Z3 (Canada)

    2009-05-30

    In spite of a high quantum efficiency in the bacterial photosynthetic reaction center (RC) the overall efficiency in a RC-based photovoltaic device is very poor partly because of an inefficient collection of charges by electrodes. To explain charge transport between the RC and an electrode a diffusion model is proposed. The numerical solution of the diffusion process describes the measured photocurrent well. An approximation of the initial condition is also made to obtain analytical expressions for the photocurrent. The model suggests that the slow transient response of the photocurrent is due to the diffusion in a biological photovoltaic device.

  15. Diffusion model for charge transfer from a photosynthetic reaction center to an electrode in a photovoltaic device

    International Nuclear Information System (INIS)

    In spite of a high quantum efficiency in the bacterial photosynthetic reaction center (RC) the overall efficiency in a RC-based photovoltaic device is very poor partly because of an inefficient collection of charges by electrodes. To explain charge transport between the RC and an electrode a diffusion model is proposed. The numerical solution of the diffusion process describes the measured photocurrent well. An approximation of the initial condition is also made to obtain analytical expressions for the photocurrent. The model suggests that the slow transient response of the photocurrent is due to the diffusion in a biological photovoltaic device.

  16. Diagnosis of ventricular drainage-related bacterial meningitis by broad-range real-time polymerase chain reaction

    DEFF Research Database (Denmark)

    Deutch, Susanna; Dahlberg, Daniel; Hedegaard, Jesper;

    2007-01-01

    OBJECTIVE: To compare a broad-range real-time polymerase chain reaction (PCR) diagnostic strategy with culture to evaluate additional effects on the etiological diagnosis and the quantification of the bacterial load during the course of ventricular drainage-related bacterial meningitis (VR...

  17. Bacterial discrimination by means of a universal array approach mediated by LDR (ligase detection reaction

    Directory of Open Access Journals (Sweden)

    Consolandi Clarissa

    2002-09-01

    Full Text Available Abstract Background PCR amplification of bacterial 16S rRNA genes provides the most comprehensive and flexible means of sampling bacterial communities. Sequence analysis of these cloned fragments can provide a qualitative and quantitative insight of the microbial population under scrutiny although this approach is not suited to large-scale screenings. Other methods, such as denaturing gradient gel electrophoresis, heteroduplex or terminal restriction fragment analysis are rapid and therefore amenable to field-scale experiments. A very recent addition to these analytical tools is represented by microarray technology. Results Here we present our results using a Universal DNA Microarray approach as an analytical tool for bacterial discrimination. The proposed procedure is based on the properties of the DNA ligation reaction and requires the design of two probes specific for each target sequence. One oligo carries a fluorescent label and the other a unique sequence (cZipCode or complementary ZipCode which identifies a ligation product. Ligated fragments, obtained in presence of a proper template (a PCR amplified fragment of the 16s rRNA gene contain either the fluorescent label or the unique sequence and therefore are addressed to the location on the microarray where the ZipCode sequence has been spotted. Such an array is therefore "Universal" being unrelated to a specific molecular analysis. Here we present the design of probes specific for some groups of bacteria and their application to bacterial diagnostics. Conclusions The combined use of selective probes, ligation reaction and the Universal Array approach yielded an analytical procedure with a good power of discrimination among bacteria.

  18. Quantum Coherence as a Witness of Vibronically Hot Energy Transfer in Bacterial Reaction Centre

    CERN Document Server

    Paleček, David; Westenhoff, Sebastian; Zigmantas, Donatas

    2016-01-01

    Photosynthetic proteins have evolved over billions of years so as to undergo optimal energy transfer to the sites of charge separation. Based on spectroscopically detected quantum coherences, it has been suggested that this energy transfer is partially wavelike. This conclusion critically depends on assignment of the coherences to the evolution of excitonic superpositions. Here we demonstrate for a bacterial reaction centre protein that long-lived coherent spectroscopic oscillations, which bear canonical signatures of excitonic superpositions, are essentially vibrational excited state coherences shifted to the ground state of the chromophores . We show that appearance of these coherences is brought about by release of electronic energy during the energy transfer. Our results establish how energy migrates on vibrationally hot chromophores in the reaction centre and they call for a re-examination of claims of quantum energy transfer in photosynthesis.

  19. Protein structure, electron transfer and evolution of prokaryotic photosynthetic reaction centers

    Science.gov (United States)

    Blankenship, R. E.

    1994-01-01

    Photosynthetic reaction centers from a variety of organisms have been isolated and characterized. The groups of prokaryotic photosynthetic organisms include the purple bacteria, the filamentous green bacteria, the green sulfur bacteria and the heliobacteria as anoxygenic representatives as well as the cyanobacteria and prochlorophytes as oxygenic representatives. This review focuses on structural and functional comparisons of the various groups of photosynthetic reaction centers and considers possible evolutionary scenarios to explain the diversity of existing photosynthetic organisms.

  20. 11. IAEA consultants' meeting of the nuclear reaction data centers. Obninsk, 7-11 October 1991

    International Nuclear Information System (INIS)

    This report summarizes the 1991 co-ordination meeting in Obninsk, Russia, of the national and regional nuclear reaction data centers, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation; the exchanged and documentation of evaluated data libraries in ENDF format, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials

  1. Photosynthetic antennas and reaction centers: Current understanding and prospects for improvement

    Energy Technology Data Exchange (ETDEWEB)

    Blankenship, R.E. [Arizona State Univ., Tempe, AZ (United States)

    1996-09-01

    A brief introduction to the principles, structures and kinetic processes that take place in natural photosynthetic reaction center complexes is presented. Energy is first collected by an antenna system, and is transferred to a reaction center complex where primary electron transfer takes place. Secondary reactions lead to oxidation of water and reduction of CO{sub 2} in some classes of organisms. Antenna systems are highly regulated to maximize energy collection efficiency while avoiding photodamage. Some areas that are presently not well understood are listed.

  2. Co-ordination of the nuclear reaction data centers. Report on an IAEA advisory group meeting

    International Nuclear Information System (INIS)

    This report summarizes the 1996 co-ordination meeting in Brookhaven, U.S.A., of the national and regional nuclear reaction data center, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ''ENDF'' format; the rapid advances of online electronic information technologies, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author). Refs, figs, tabs

  3. Co-ordination of the nuclear reactions data centers. Report on an IAEA advisory group meeting

    International Nuclear Information System (INIS)

    This report summarizes the 1998 co-ordination meeting at the IAEA Headquarters in Vienna of the regional, national and specialized nuclear reaction data centers, concerned by the IAEA at two-year intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation and data center services; the exchange and documentation of evaluated data libraries in ''ENDF'' format; the rapid advances of online electronic information technologies, with goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials. The scope of data covers microscopic cross-sections and related parameters of nuclear reactions induced by neutrons, charged-particles and photons. (author)

  4. Manipulation of prenylation reactions by structure-based engineering of bacterial indolactam prenyltransferases

    Science.gov (United States)

    Mori, Takahiro; Zhang, Lihan; Awakawa, Takayoshi; Hoshino, Shotaro; Okada, Masahiro; Morita, Hiroyuki; Abe, Ikuro

    2016-03-01

    Prenylation reactions play crucial roles in controlling the activities of biomolecules. Bacterial prenyltransferases, TleC from Streptomyces blastmyceticus and MpnD from Marinactinospora thermotolerans, catalyse the `reverse' prenylation of (-)-indolactam V at the C-7 position of the indole ring with geranyl pyrophosphate or dimethylallyl pyrophosphate, to produce lyngbyatoxin or pendolmycin, respectively. Using in vitro analyses, here we show that both TleC and MpnD exhibit relaxed substrate specificities and accept various chain lengths (C5-C25) of the prenyl donors. Comparisons of the crystal structures and their ternary complexes with (-)-indolactam V and dimethylallyl S-thiophosphate revealed the intimate structural details of the enzyme-catalysed `reverse' prenylation reactions and identified the active-site residues governing the selection of the substrates. Furthermore, structure-based enzyme engineering successfully altered the preference for the prenyl chain length of the substrates, as well as the regio- and stereo-selectivities of the prenylation reactions, to produce a series of unnatural novel indolactams.

  5. Reengineering the optical absorption cross-section of photosynthetic reaction centers.

    Science.gov (United States)

    Dutta, Palash K; Lin, Su; Loskutov, Andrey; Levenberg, Symon; Jun, Daniel; Saer, Rafael; Beatty, J Thomas; Liu, Yan; Yan, Hao; Woodbury, Neal W

    2014-03-26

    Engineered cysteine residues near the primary electron donor (P) of the reaction center from the purple photosynthetic bacterium Rhodobacter sphaeroides were covalently conjugated to each of several dye molecules in order to explore the geometric design and spectral requirements for energy transfer between an artificial antenna system and the reaction center. An average of 2.5 fluorescent dye molecules were attached at specific locations near P. The enhanced absorbance cross-section afforded by conjugation of Alexa Fluor 660 dyes resulted in a 2.2-fold increase in the formation of reaction center charge-separated state upon intensity-limited excitation at 650 nm. The effective increase in absorbance cross-section resulting from the conjugation of two other dyes, Alexa Fluor 647 and Alexa Fluor 750, was also investigated. The key parameters that dictate the efficiency of dye-to-reaction center energy transfer and subsequent charge separation were examined using both steady-state and time-resolved fluorescence spectroscopy as well as transient absorbance spectroscopy techniques. An understanding of these parameters is an important first step toward developing more complex model light-harvesting systems integrated with reaction centers. PMID:24568563

  6. Replacement of bacteriopheophytin in reaction centers from Rhodobacter sphaeroides RS601 with plant pheophytin

    Institute of Scientific and Technical Information of China (English)

    曾小华; 吴永强; 沈允钢; 徐春和

    2000-01-01

    In the presence of acetone and an excess of exogenous plant pheophytins, bacterio-pheophytins in the reaction centers from Rhodobacter sphaeroides RS601 were replaced by pheophytins at sites HA and HB, when incubated at 43.5℃ for more than 15 min. The substitution of bacteriopheophytins in the reaction centers was 50% and 71% with incubation of 15 and 60 min, respectively. In the absorption spectra of pheophytin-replaced reaction centers (Phe RCs), bands assigned to the transition moments Qx (537 nm) and QY (758 nm) of bacteriopheophytin disappeared, and three distinct bands assigned to the transition moments Qx (509/542 nm) and QY (674 nm) of pheophytin appeared instead. Compared to that of the control reaction centers, the photochemical activities of Phe RCs are 78% and 71% of control, with the incubation time of 15 and 60 min. Differences might exist between the redox properties of Phe RC and of native reaction centers, but the substitution is significant, and the new system is available for further

  7. Investigation of polymerase chain reaction assays to improve detection of bacterial involvement in bovine respiratory disease.

    Science.gov (United States)

    Bell, Colin J; Blackburn, Paul; Elliott, Mark; Patterson, Tony I A P; Ellison, Sean; Lahuerta-Marin, Angela; Ball, Hywel J

    2014-09-01

    Bovine respiratory disease (BRD) causes severe economic losses to the cattle farming industry worldwide. The major bacterial organisms contributing to the BRD complex are Mannheimia haemolytica, Histophilus somni, Mycoplasma bovis, Pasteurella multocida, and Trueperella pyogenes. The postmortem detection of these organisms in pneumonic lung tissue is generally conducted using standard culture-based techniques where the presence of therapeutic antibiotics in the tissue can inhibit bacterial isolation. In the current study, conventional and real-time polymerase chain reaction (PCR) assays were used to assess the prevalence of these 5 organisms in grossly pneumonic lung samples from 150 animals submitted for postmortem examination, and the results were compared with those obtained using culture techniques. Mannheimia haemolytica was detected in 51 cases (34%) by PCR and in 33 cases (22%) by culture, H. somni was detected in 35 cases (23.3%) by PCR and in 6 cases (4%) by culture, Myc. bovis was detected in 53 cases (35.3%) by PCR and in 29 cases (19.3%) by culture, P. multocida was detected in 50 cases (33.3%) by PCR and in 31 cases (20.7%) by culture, and T. pyogenes was detected in 42 cases (28%) by PCR and in 31 cases (20.7%) by culture, with all differences being statistically significant. The PCR assays indicated positive results for 111 cases (74%) whereas 82 cases (54.6%) were culture positive. The PCR assays have demonstrated a significantly higher rate of detection of all 5 organisms in cases of pneumonia in cattle in Northern Ireland than was detected by current standard procedures.

  8. Stark effect in wild-type and heterodimer-containing reaction centers from Rhodobacter capsulatus

    International Nuclear Information System (INIS)

    The effect of an external electric field on the optical absorption spectra of wild-type Rhodobacter capsulatus and two Rb. capsulatus reaction centers that have been genetically modified through site-directed mutagenesis was measured at 77 K. The two genetically modified reaction centers replace histidine M200, the axial ligand to the M-side bacteriochlorophyll of the special pair, with either leucine or phenylalanine. These substitutions results in the replacement of the M-side bacteriochlorophyll with bacteriopheophytin, forming a bacteriochlorophyll-bacteriopheophytin heterodimer. The magnitude of the change in dipole moment from the ground to excited state (Δμapp) and the angle δ between the Qy transition moment and the direction of Δμapp were measured for the special pair absorption band for all three reaction centers. The differences in the magnitude of Δμapp and the angle δ between wild-type and heterodimer reaction centers are consistent with increased charge transfer in the heterodimer special pair. These results support calculations that place the special pair charge-transfer state higher in energy than the excited singlet state in wild-type Rb. capsulatus RCs

  9. Continuum probe two-dimensional electronic spectroscopy of the photosystem II reaction center

    Directory of Open Access Journals (Sweden)

    Ogilvie J. P.

    2013-03-01

    Full Text Available We report two-dimensional electronic spectroscopy of the photosystem II reaction center, collected in the pump-probe geometry employing a continuum probe. This enables observation of ion bands that report on intermediates in the charge separation process.

  10. Immobilization of bacterial luciferase into poly(N-isopropylacrylamide) film for electrochemical control of a bioluminescence reaction

    International Nuclear Information System (INIS)

    A poly(N-isopropylacrylamide) film was modified on an indium-tin oxide electrode in order to immobilize bacterial luciferase (BL) on the electrode surface. By using the modified electrode, flavin mononucleotide (FMN) was electrochemically reduced to FMNH2, which is one of the substrates of the BL luminescence reaction, to control the bioluminescence reaction by BL. The BL reaction in the modified film could be promoted and controlled by the electrochemical generation of FMNH2. This BL luminescence system was evaluated as a model system for the inhibitory assay of hydrophobic molecules on protein functions. (author)

  11. Study of Bacterial Infections among Burn Patients Hospitalized in Isfahan Burn Center

    Directory of Open Access Journals (Sweden)

    J. Faghri

    2007-10-01

    Full Text Available Introduction & Objective: Burn patients are at risk of acquiring infection because of destroy skin barrier, suppression of immunity, prolonged hospitalization, and invasive therapeutic and diagnostic procedure, risk of acquiring infection is high among burned patients. The aim of this study was to assess the incidence rate of bacterial etiology and infections among burn patients in the burn center of Isfahan. Materials & Methods: The study was conducted descriptive – cross sectional during a period of one year, (from august 2004 until September 2005. A total of 106 patients presenting with no signs and symptoms of infection within the first 48 hours of admission were included. CDC definition for nosocomial infections was applied. Each patient’s clinical examinations and records investigated daily. Swab culture, blood culture (during fever time, tissue culture from biopsy specimen of burn wound and urine culture obtained. The data were analyzed and interpreted using SPSS 10 Software, using Chi – square and Kappa Coefficient. P.value < 0.05 was significant. Results: One-hundred and six patients met the inclusion criteria, 91 (85/8% acquired at least one type of infection, including, urinary tract 28 (26/4%, blood stream 30 (28/3%, and burn wound 91(85/8%. Pseudomonas aeroginosa was the most common causative agent isolated from blood culture and swab culture, 27/42% and 54/4% respectively. Also, E.coli was the major casautive agent of urinary tract infections (6.4% isolated from urine culture of these burn patients.Conclusion: The results indicated that, biopsy from burn wounds and study of histopathologic specimen day by other day depends on blood and urine culture conditions overall can be effective for early detection of burn wounds infections.

  12. Quantum nonequilibrium approach for fast electron transport in open systems: photosynthetic reaction centers.

    Science.gov (United States)

    Pudlak, M; Pichugin, K N; Nazmitdinov, R G; Pincak, R

    2011-11-01

    Creation of electrons or excitons by external fields in a system with initially statistically independent unrelaxed vibrational modes leads to an initial condition term. The contribution of this term in the time convolution generalized master-equation approach is studied in the second order of the perturbation theory in path-integral formalism. The developed approach, applied for the analysis of dynamics in the photosynthetic reaction center, exhibits the key role of the initial condition terms at the primary stage of electron transfer.

  13. Dynamical theory of primary processes of charge separation in the photosynthetic reaction center.

    Science.gov (United States)

    Lakhno, Victor D

    2005-05-01

    A dynamical theory has been developed for primary separation of charges in the course of photosynthesis. The theory deals with both hopping and superexchange transfer mechanisms. Dynamics of electron transfer from dimeric bacteriochlorophyll to quinone has been calculated. The results obtained agree with experimental data and provide a unified explanation of both the hierarchy of the transfer time in the photosynthetic reaction center and the phenomenon of coherent oscillations accompanying the transfer process.

  14. Seasonal Dynamics of the Airborne Bacterial Community and Selected Viruses in a Children’s Daycare Center

    Science.gov (United States)

    Prussin, Aaron J.; Vikram, Amit; Bibby, Kyle J.; Marr, Linsey C.

    2016-01-01

    Children’s daycare centers appear to be hubs of respiratory infectious disease transmission, yet there is only limited information about the airborne microbial communities that are present in daycare centers. We have investigated the microbial community of the air in a daycare center, including seasonal dynamics in the bacterial community and the presence of specific viral pathogens. We collected filters from the heating, ventilation, and air conditioning (HVAC) system of a daycare center every two weeks over the course of a year. Amplifying and sequencing the 16S rRNA gene revealed that the air was dominated by Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes that are commonly associated with the human skin flora. Clear seasonal differences in the microbial community were not evident; however, the community structure differed when the daycare center was closed and unoccupied for a 13-day period. These results suggest that human occupancy, rather than the environment, is the major driver in shaping the microbial community structure in the air of the daycare center. Using PCR for targeted viruses, we detected a seasonal pattern in the presence of respiratory syncytial virus that included the period of typical occurrence of the disease related to the virus; however, we did not detect the presence of adenovirus or rotavirus at any time. PMID:26942410

  15. Frequency of bacterial isolates and pattern of antimicrobial resistance in patients with hematological malignancies: A snapshot from tertiary cancer center

    Directory of Open Access Journals (Sweden)

    M Sengar

    2015-01-01

    Full Text Available BACKGROUND: Infections are the most important cause of mortality in patients with high-risk febrile neutropenia. Emergence of multi-drug resistant organisms (MDROs has become a major challenge for hemato-oncologists. Knowledge of the prevalent organisms and their antimicrobial sensitivity can help deciding the empirical therapy at individual centers and allows timely measures to reduce the risk of antimicrobial resistance. AIMS: To evaluate the frequency of bacterial isolates from all the samples and the pattern of bacterial bloodstream infections and incidence of MDROs. SETTINGS AND DESIGN: This is a retrospective analysis from a tertiary care cancer center. MATERIALS AND METHODS: From January to June 2014 information on all the samples received in Department of Microbiology was collected retrospectively. The data from samples collected from patients with hematological cancers were analyzed for types of bacterial isolates and antimicrobial sensitivity. RESULTS: A total of 739 isolates were identified with 67.9% of isolates being Gram-negative. The predominant Gram-negative organisms were Escherichia coli, Psuedomonas spp. and Klebsiella spp. Among the bacterial bloodstream infections, 66% were Gram-negative isolates. MDROs constituted 22% of all isolates in blood cultures. Incidence of resistant Gram-positive organisms was low in the present dataset (methicillin resistant Staphylococcus aureus and vancomycin-resistant enterococci-1.3%. CONCLUSIONS: The analysis reconfirms the Gram-negative organisms as the predominant pathogens in bacteremia seen in patients with hematological cancers. The high frequency of multi-drug resistance in the dataset calls for the need of emergency measures to curtail further development and propagation of resistant organisms.

  16. Formation of photosystem II reaction centers that work as energy sinks in lichen symbiotic Trebouxiophyceae microalgae.

    Science.gov (United States)

    Guéra, Alfredo; Gasulla, Francisco; Barreno, Eva

    2016-04-01

    Lichens are poikilohydric symbiotic organisms that can survive in the absence of water. Photosynthesis must be highly regulated in these organisms, which live under continuous desiccation-rehydration cycles, to avoid photooxidative damage. Analysis of chlorophyll a fluorescence induction curves in the lichen microalgae of the Trebouxiophyceae Asterochloris erici and in Trebouxia jamesii (TR1) and Trebouxia sp. (TR9) phycobionts, isolated from the lichen Ramalina farinacea, shows differences with higher plants. In the presence of the photosynthetic electron transport inhibitor DCMU, the kinetics of Q(A) reduction is related to variable fluorescence by a sigmoidal function that approaches a horizontal asymptote. An excellent fit to these curves was obtained by applying a model based on the following assumptions: (1) after closure, the reaction centers (RCs) can be converted into "energy sink" centers (sRCs); (2) the probability of energy leaving the sRCs is very low or zero and (3) energy is not transferred from the antenna of PSII units with sRCs to other PSII units. The formation of sRCs units is also induced by repetitive light saturating pulses or at the transition from dark to light and probably requires the accumulation of reduced Q(A), as well as structural changes in the reaction centers of PSII. This type of energy sink would provide a very efficient way to protect symbiotic microalgae against abrupt changes in light intensity. PMID:26482588

  17. Polymerase Chain Reaction (PCR) Versus Bacterial Culture in Detection of Organisms in Otitis Media with Effusion (OME) in Children.

    Science.gov (United States)

    Aly, Balegh H; Hamad, Mostafa S; Mohey, Mervat; Amen, Sameh

    2012-03-01

    The aim of this study was to compare between polymerase chain reaction (PCR) and bacterial culture in detection of Streptococcus Pneumonia and M. Catarrhalis in otitis media with effusion (OME) in children. Fifty patients having OME were included in this study between 2003 and 2008. Myringotomy and tympanostomy tube insertion were done in every patient and the middle ear effusion samples were aspirated. The samples were subjected to bacteriological study in the form of culture and molecular study in the form of PCR using JM201/202-204 primer probe set for both S. pneumonia and M. catarrhalis. The results of Bacterial cultures are as follows: five cases (10%) were culture positive for S. pneumonia. Six cases (12%) were culture positive for M. catarrhalis. Only one case (2%) showed positively for both S. pneumonia and M. catarrhalis. Polymerase chain reaction test shows that 18 cases (36%) were positive for S. pneumonia, 22 cases (44%) were positive for M. catarrhalis, 6 cases (12%) were positive for both organism and 4 cases (8%) were negative. The difference between the proportion of culture positive and PCR positive specimens for both organisms individually and collectively was significant (P PCR is more accurate than bacterial culture in detection of organisms in middle ear fluid in OME and that M. catarrhalis plays a significant rule in OME as it is the sole organism identified more than the other one by PCR.

  18. Quantum non-equilibrium approach for fast electron transport in open systems: photosynthetic reaction centers

    CERN Document Server

    Pudlak, M; Nazmitdinov, R G; Pincak, R

    2011-01-01

    Creation of electron or exciton by external fields in a system with initially statistically independent unrelaxed vibrational modes leads to an initial condition term. The contribution of this term in the time convolution generalized master equation approach is studied in second order of the perturbation theory for electron-phonon coupling in the parth integral formalism. The developed approach, applied for analysis of dynamics in the photosynthetic reaction center, exhibits the key role of the initial condition term at the primary stage of electron transfer.

  19. A theoretical study of electronic excited states of photosynthetic reaction center in Rhodopseudomonas viridis

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The electronic singlet vertical excited states of photosynthetic reaction center (PSRC) in Rhodopseudomonas (Rps.) viridis were investigated by ZINDO and INDO/S methods. The effects of the interactions of pigment-pigment and pigment-protein on the electronic excitations were examined. The calculation results showed that the interactions of pigment-pigment and pigment-protein play an important role in reasonably assigning the experimental absorption and circular dichroism (CD) spectra of PSRC in Rps. virids. By comparing the theoretically computed excited states with the experimental absorption and CD spectra, satisfactory assignments of the experimental spectroscopic peaks were achieved.

  20. Brominated lipids identify lipid binding sites on the surface of the reaction center from Rhodobacter sphaeroides.

    Science.gov (United States)

    Roszak, Aleksander W; Gardiner, Alastair T; Isaacs, Neil W; Cogdell, Richard J

    2007-03-20

    This study describes the use of brominated phospholipids to distinguish between lipid and detergent binding sites on the surface of a typical alpha-helical membrane protein. Reaction centers isolated from Rhodobacter sphaeroides were cocrystallized with added brominated phospholipids. X-ray structural analysis of these crystals has revealed the presence of two lipid binding sites from the characteristic strong X-ray scattering from the bromine atoms. These results demonstrate the usefulness of this approach to mapping lipid binding sites at the surface of membrane proteins.

  1. "ETIOLOGY AND ANTIBACTERIAL RESISTANCE OF BACTERIAL URINARY TRACT INFECTIONS IN CHILDREN’S MEDICAL CENTER, TEHRAN, IRAN"

    Directory of Open Access Journals (Sweden)

    M. Haghi-Ashteiani

    2007-06-01

    Full Text Available Urinary tract infection (UTI is a common bacterial illness in children. Knowledge of the antimicrobial resistance patterns of common uropathogens in children according to local epidemiology is essential for providing clinically appropriate, cost effective therapy for UTI. The aim of this study was to determine the distribution of urinary tract infections in a referral hospital, Children’s Medical Center, and determination of in vitro susceptibility of these organisms to antimicrobial agents. Of the 1231 bacterial isolates the most frequent isolates were Escherichia coli (38.66%, Klebsiella spp. (22.25%, Coagulase-negative staphylococci (10.1%, Pseudomonas spp. (8.7%, enterococci (8.28%, Enterobacter spp. (4.1%, staphylococcus aureus (3.24%, and proteus mirabilis (2.9%. Among Enterobacteriaceae, 79.80% of E. coli were amikacin-sensitive. Of Gram-positive cocci, 66.66% of staphylococcus aureus were vancomycin-sensitive. Our data show the original distribution of uropathogens from UTIs in children referred to Children’s Medical Center in Tehran and the emergence of multidrug resistant strains.

  2. Isolated photosystem I reaction centers on a functionalized gated high electron mobility transistor.

    Science.gov (United States)

    Eliza, Sazia A; Lee, Ida; Tulip, Fahmida S; Mostafa, Salwa; Greenbaum, Elias; Ericson, M Nance; Islam, Syed K

    2011-09-01

    In oxygenic plants, photons are captured with high quantum efficiency by two specialized reaction centers (RC) called Photosystem I (PS I) and Photosystem II (PS II). The captured photon triggers rapid charge separation and the photon energy is converted into an electrostatic potential across the nanometer-scale (~6 nm) reaction centers. The exogenous photovoltages from a single PS I RC have been previously measured using the technique of Kelvin force probe microscopy (KFM). However, biomolecular photovoltaic applications require two-terminal devices. This paper presents for the first time, a micro-device for detection and characterization of isolated PS I RCs. The device is based on an AlGaN/GaN high electron mobility transistor (HEMT) structure. AlGaN/GaN HEMTs show high current throughputs and greater sensitivity to surface charges compared to other field-effect devices. PS I complexes immobilized on the floating gate of AlGaN/GaN HEMTs resulted in significant changes in the device characteristics under illumination. An analytical model has been developed to estimate the RCs of a major orientation on the functionalized gate surface of the HEMTs.

  3. Modeling light-driven proton pumps in artificial photosynthetic reaction centers.

    Science.gov (United States)

    Ghosh, Pulak Kumar; Smirnov, Anatoly Yu; Nori, Franco

    2009-07-21

    We study a model of a light-induced proton pump in artificial reaction centers. The model contains a molecular triad with four electron states (i.e., one donor state, two photosensitive group states, and one acceptor state) as well as a molecular shuttle having one electron and one proton-binding sites. The shuttle diffuses between the sides of the membrane and translocates protons energetically uphill: from the negative side to the positive side of the membrane, harnessing for this purpose the energy of the electron-charge separation produced by light. Using the methods of quantum transport theory we calculate the range of light intensity and transmembrane potentials that maximize both the light-induced proton current and the energy transduction efficiency. We also study the effect of temperature on proton pumping. The light-induced proton pump in our model gives a quantum yield of proton translocation of about 55%. Thus, our results explain previous experiments on these artificial photosynthetic reaction centers.

  4. The kinetic model for slow photoinduced electron transport in the reaction centers of purple bacteria.

    Science.gov (United States)

    Serdenko, T V; Barabash, Y M; Knox, P P; Seifullina, N Kh

    2016-12-01

    The present work is related to the investigation of slow kinetics of electron transport in the reaction centers (RCs) of Rhodobacter sphaeroides. Experimental data on the absorption kinetics of aqueous solutions of reaction centers at different modes of photoexcitation are given. It is shown that the kinetics of oxidation and reduction of RCs are well described by the sum of three exponential functions. This allows to suggest a two-level kinetic model for electron transport in the RC as a system of four electron-conformational states which correspond to three balance differential equations combined with state equation. The solution of inverse problem made it possible to obtain the rate constant values in kinetic equations for different times and intensities of exciting light. Analysis of rate constant values in different modes of RC excitation allowed to suggest that two mechanisms of structural changes are involved in RC photo-oxidation. One mechanism leads to the increment of the rate of electron return, another one-to its drop. Structural changes were found out to occur in the RCs under incident light. After light was turned off, the reduction of RCs was determined by the second mechanism. PMID:27271854

  5. Deactivation of excitation energy in bacterial photosynthetic reaction centres in Langmuir-Blodgett films

    Science.gov (United States)

    Miyake, J.; Hara, M.; Goc, J.; Planner, A.; Wróbel, D.

    1997-08-01

    Absorption, photoacoustic and time-resolved in μs time range delayed luminescence spectra have been measured in order to follow the interaction among chromophores when Rhodobacter sphaeroides and Rhodopseudomonas viridis reaction centres are closely packed in a form of Langmuir-Blodgett multilayers. Two types of Langmuir-Blodgett samples have been prepared and investigated: multilayers consist of one type of reaction centre ( Rhodobacter sphaeroides or Rhodopseudomonas viridis) and multilayers composed of mixed reaction centres ( Rhodobacter sphaeroides mixed with Rhodopseudomonas viridis). Using the Langmuir-Blodgett multilayers composed of two types of bacteria reaction centres mixture, we were able to extend the spectral region of the light/solar energy absorbed by the system. It was shown that each form of pigment participates in thermal dissipation but to a different degree. A special pair (bacteriochlorophyll dimer) does not contribute to delayed luminescence. Delayed luminescence in Rhodopseudomonas viridis and Rhodobacter sphaeroides differs very significantly from each other. Bacteriopheophytin as well as dihydromesochlorophyll contribute to delayed luminescence but the degree of their participation in this radiative process depends strongly on the type of reaction centre. Delayed luminescence and thermal processes have been indicated as important processes of deactivation of the photoexcited chromophores in reaction centres.

  6. The action of the bacterial toxin microcin B17. Insight into the cleavage-religation reaction of DNA gyrase.

    Science.gov (United States)

    Pierrat, Olivier A; Maxwell, Anthony

    2003-09-12

    We have examined the effects of the bacterial toxin microcin B17 (MccB17) on the reactions of Escherichia coli DNA gyrase. MccB17 slows down but does not completely inhibit the DNA supercoiling and relaxation reactions of gyrase. A kinetic analysis of the cleavage-religation equilibrium of gyrase was performed to determine the effect of the toxin on the forward (cleavage) and reverse (religation) reactions. A simple mechanism of two consecutive reversible reactions with a nicked DNA intermediate was used to simulate the kinetics of cleavage and religation. The action of MccB17 on the kinetics of cleavage and religation was compared with that of the quinolones ciprofloxacin and oxolinic acid. With relaxed DNA as substrate, only a small amount of gyrase cleavage complex is observed with MccB17 in the absence of ATP, whereas the presence of the nucleotide significantly enhances the effect of the toxin on both the cleavage and religation reactions. In contrast, ciprofloxacin, oxolinic acid, and Ca2+ show lesser dependence on ATP to stabilize the cleavage complex. MccB17 enhances the overall rate of DNA cleavage by increasing the forward rate constant (k2) of the second equilibrium. In contrast, ciprofloxacin increases the amount of cleaved DNA by a combined effect on the forward and reverse rate constants of both equilibria. Based on these results and on the observations that MccB17 only slowly inhibits the supercoiling and relaxation reactions, we suggest a model of the interaction of MccB17 with gyrase.

  7. Origin of bimodal fluorescence enhancement factors of Chlorobaculum tepidum reaction centers on silver island films.

    Science.gov (United States)

    Maćkowski, Sebastian; Czechowski, Nikodem; Ashraf, Khuram U; Szalkowski, Marcin; Lokstein, Heiko; Cogdell, Richard J; Kowalska, Dorota

    2016-08-01

    We focus on the spectral dependence of plasmon-induced enhancement of fluorescence of Chlorobaculum tepidum reaction centers. When deposited on silver island film, they exhibit up to a 60-fold increase in fluorescence. The dependence of enhancement factors on the excitation wavelength is not correlated with the absorption spectrum of the plasmonic structure. In particular, the presence of one (or multiple) trimers of the Fenna-Matthews-Olson (FMO) protein reveals itself in bimodal distribution of enhancement factors for the excitation at 589 nm, the wavelength corresponding to bacteriochlorophyll absorption of FMO and the core of the RC. We conclude that the structure of multichromophoric complexes can substantially affect the impact of plasmonic excitations, which is important in the context of assembling functional biohybrid systems. PMID:27406896

  8. Origin of bimodal fluorescence enhancement factors of Chlorobaculum tepidum reaction centers on silver island films.

    Science.gov (United States)

    Maćkowski, Sebastian; Czechowski, Nikodem; Ashraf, Khuram U; Szalkowski, Marcin; Lokstein, Heiko; Cogdell, Richard J; Kowalska, Dorota

    2016-08-01

    We focus on the spectral dependence of plasmon-induced enhancement of fluorescence of Chlorobaculum tepidum reaction centers. When deposited on silver island film, they exhibit up to a 60-fold increase in fluorescence. The dependence of enhancement factors on the excitation wavelength is not correlated with the absorption spectrum of the plasmonic structure. In particular, the presence of one (or multiple) trimers of the Fenna-Matthews-Olson (FMO) protein reveals itself in bimodal distribution of enhancement factors for the excitation at 589 nm, the wavelength corresponding to bacteriochlorophyll absorption of FMO and the core of the RC. We conclude that the structure of multichromophoric complexes can substantially affect the impact of plasmonic excitations, which is important in the context of assembling functional biohybrid systems.

  9. Photoprotection of reaction centers: thermal dissipation of absorbed light energy vs charge separation in lichens.

    Science.gov (United States)

    Heber, Ulrich; Soni, Vineet; Strasser, Reto J

    2011-05-01

    During desiccation, fluorescence emission and stable light-dependent charge separation in the reaction centers (RCs) of photosystem II (PSII) declined strongly in three different lichens: in Parmelia sulcata with an alga as the photobiont, in Peltigera neckeri with a cyanobacterium and in the tripartite lichen Lobaria pulmonaria. Most of the decline of fluorescence was caused by a decrease in the quantum efficiency of fluorescence emission. It indicated the activation of photoprotective thermal energy dissipation. Photochemical activity of the RCs was retained even after complete desiccation. It led to light-dependent absorption changes and found expression in reversible increases in fluorescence or in fluorescence quenching. Lowering the temperature changed the direction of fluorescence responses in P. sulcata. The observations are interpreted to show that reversible light-induced increases in fluorescence emission in desiccated lichens indicate the functionality of the RCs of PSII. Photoprotection is achieved by the drainage of light energy to dissipating centers outside the RCs before stable charge separation can take place. Reversible quenching of fluorescence by strong illumination is suggested to indicate the conversion of the RCs from energy conserving to energy dissipating units. This permits them to avoid photoinactivation. On hydration, re-conversion occurs to energy-conserving RCs. PMID:21029105

  10. Study of quark flow in exclusive reactions at 90 degrees in the center of mass (AGS E838)

    International Nuclear Information System (INIS)

    We report a study of quark flow in 20 exclusive reactions measured at Brookhaven National Laboratory's AGS with a beam momentum of 5.9 GeV/c at 90 degree in the center of mass. This experiment confirms the strong quark flow reaction mechanism dependence of two-body hadron scattering at large angles seen at 9.9 GeV/c. Large differences in cross sections for different reactions are consistent with the dominance of quark interchange in these 90 degree reactions, and indicate that pure gluon exchange and quark/antiquark annihilation diagrams are less important. copyright 1995 American Institute of Physics

  11. Lactic Acid Yield Using Different Bacterial Strains, Its Purification, and Polymerization through Ring-Opening Reactions

    Directory of Open Access Journals (Sweden)

    F. G. Orozco

    2014-01-01

    Full Text Available Laboratory-scale anaerobic fermentation was performed to obtain lactic acid from lactose, using five lactic acid bacteria: Lactococcus lactis, Lactobacillus bulgaricus, L. delbrueckii, L. plantarum, and L. delbrueckii lactis. A yield of 0.99 g lactic acid/g lactose was obtained with L. delbrueckii, from which a final concentration of 80.95 g/L aqueous solution was obtained through microfiltration, nanofiltration, and inverse osmosis membranes. The lactic acid was polymerized by means of ring-opening reactions (ROP to obtain poly-DL-lactic acid (PDLLA, with a viscosity average molecular weight (Mv of 19,264 g/mol.

  12. Self-assembling photosynthetic reaction centers on electrodes for current generation.

    Science.gov (United States)

    Nakamura, C; Hasegawa, M; Yasuda, Y; Miyake, J

    2000-01-01

    Photosynthetic reaction centers (RCs) made from photosynthetic organisms can be used in solar batteries because their molecules cause light-induced charge separation. We present a simple immobilization system of the intact RCs from Rhodobacter sphaeroides on an electrode that uses nickel ligand binding by the hexameric histidine tag on H subunit (HHisRC). The binding constant of HHisRC to the nickel-nitrilotriacetic acid (Ni-NTA) chip measured with a surface plasmon resonance instrument was 1.6 x 10(8) M-1. HHisRCs were immobilized on an indium tin oxide electrode overlaid with an Ni-NTA gold substrate. The photoinduced displacement current of this electrode was measured to estimate the orientation of HHisRC on the electrode, and the detachability of HHisRC from the electrode was determined by using an imidazole solution wash. The direction of the flash-light-induced displacement current suggested that the H subunit side of the immobilized HHisRC faced the surface of the electrode. The photoinduced current disappeared after the electrode was washed in the imidazole solution. This simple immobilization and detachment of HHisRC to the electrode might be useful for making a reproducible photocurrent device. PMID:10849806

  13. A protein dynamics study of photosystem II: the effects of protein conformation on reaction center function.

    Science.gov (United States)

    Vasil'ev, Sergej; Bruce, Doug

    2006-05-01

    Molecular dynamics simulations have been performed to study photosystem II structure and function. Structural information obtained from simulations was combined with ab initio computations of chromophore excited states. In contrast to calculations based on the x-ray structure, the molecular-dynamics-based calculations accurately predicted the experimental absorbance spectrum. In addition, our calculations correctly assigned the energy levels of reaction-center (RC) chromophores, as well as the lowest-energy antenna chlorophyll. The primary and secondary quinone electron acceptors, Q(A) and Q(B), exhibited independent changes in position over the duration of the simulation. Q(B) fluctuated between two binding sites similar to the proximal and distal sites previously observed in light- and dark-adapted RC from purple bacteria. Kinetic models were used to characterize the relative influence of chromophore geometry, site energies, and electron transport rates on RC efficiency. The fluctuating energy levels of antenna chromophores had a larger impact on quantum yield than did their relative positions. Variations in electron transport rates had the most significant effect and were sufficient to explain the experimentally observed multi-component decay of excitation in photosystem II. The implications of our results are discussed in the context of competing evolutionary selection pressures for RC structure and function.

  14. Assembly of photosynthetic reaction center with ABA tri-block polymersomes: highlights on the protein localization.

    KAUST Repository

    Tangorra, Roberto Rocco

    2015-07-07

    The reconstitution of the integral membrane protein photosynthetic reaction center (RC) in polymersomes, i. e. artificial closed vesicles, was achieved by the micelle-to-vesicle transition technique, a very mild protocol based on size exclusion chromatography often used to drive the incorporation of proteins contemporarily to liposomes formation. An optimized protocol was used to successfully reconstitute the protein in a fully active state in polymersomes formed by the tri-block copolymers PMOXA22-PDMS61-PMOXA22. The RC is very sensitive to its solubilizing environment and was used to probe the positioning of the protein in the vesicles. According to charge-recombination experiments and to the enzymatic activity assay, the RC is found to accommodate in the PMOXA22 region of the polymersome, facing the water bulk solution, rather than in the PDMS61 transmembrane-like region. Furthermore, polymersomes were found to preserve protein integrity efficiently as the biomimetic lipid bilayers but show a much longer temporal stability than lipid based vesicles.

  15. Reconstitution of Photosystem Ⅱ Reaction Center with Cu-Chlorophyll a

    Institute of Scientific and Technical Information of China (English)

    Shuang Liu; Feng-Qin Dong; Chun-Hong Yang; Chong-Qin Tang; Ting-Yun Kuang

    2006-01-01

    An isolated photosystem (PS) Ⅱ reaction center (RC) with altered pigment content was obtained by chemical exchange of native chlorophyll a (Chl) with externally added Cu-Chl a (Cu-Chl). Pigment composition and spectroscopic properties of the RC exchanged with Cu-Chl were compared with native RC and RC treated with Chl in the same way. High-performance liquid chromatography analysis showed approximately 0.5 Cu-Chl per two pheophytin in the Cu-Chl-reconstituted RC preparation. Insertion of Cu-Chl resulted in a decrease in absorption at 670 nm and an increase at 660 nm, suggesting that the peripheral Chl may have been displaced. Fluorescence emission spectra of the Cu-Chl-reconstituted RC displayed a marked decrease in fluorescence yield and a blue shift of the band maximum, accompanied by the appearance of a broad peak at a shorter wavelength, indicating that energy transfer in the modified RC was disturbed by Cu-Chl, a quencher of the excited state. However, there were few differences in the circular dichroism (CD) spectra,suggesting that the arrangement of pigments and proteins responsible for the CD signal was not significantly affected. In addition, no obvious change in peptide components was found after the exchange procedure.

  16. Native Mass Spectrometry Characterizes the Photosynthetic Reaction Center Complex from the Purple Bacterium Rhodobacter sphaeroides

    Science.gov (United States)

    Zhang, Hao; Harrington, Lucas B.; Lu, Yue; Prado, Mindy; Saer, Rafael; Rempel, Don; Blankenship, Robert E.; Gross, Michael L.

    2016-08-01

    Native mass spectrometry (MS) is an emerging approach to study protein complexes in their near-native states and to elucidate their stoichiometry and topology. Here, we report a native MS study of the membrane-embedded reaction center (RC) protein complex from the purple photosynthetic bacterium Rhodobacter sphaeroides. The membrane-embedded RC protein complex is stabilized by detergent micelles in aqueous solution, directly introduced into a mass spectrometer by nano-electrospray (nESI), and freed of detergents and dissociated in the gas phase by collisional activation. As the collision energy is increased, the chlorophyll pigments are gradually released from the RC complex, suggesting that native MS introduces a near-native structure that continues to bind pigments. Two bacteriochlorophyll a pigments remain tightly bound to the RC protein at the highest collision energy. The order of pigment release and their resistance to release by gas-phase activation indicates the strength of pigment interaction in the RC complex. This investigation sets the stage for future native MS studies of membrane-embedded photosynthetic pigment-protein and related complexes.

  17. Photosynthetic electron transfer from reaction center pigment-protein complex in silica nanopores.

    Science.gov (United States)

    Oda, Ippei; Iwaki, Masayo; Fujita, Daiju; Tsutsui, Yasutaka; Ishizaka, Souji; Dewa, Makiko; Nango, Mamoru; Kajino, Tsutomu; Fukushima, Yoshiaki; Itoh, Shigeru

    2010-08-17

    A photosynthetic reaction center (RC) pigment-protein complex purified from a thermophilic purple photosynthetic bacterium, Thermochromatium tepidum, was adsorbed to a folded-sheet silica mesoporous material (FSM). The RC has a molecular structure with a 7.0 x 5.0 x 13 nm diameter. The amount of RC adsorbed to the FSM compound with an average internal pore diameter of 7.9 nm (FSM(7.9)) was high at 0.29 gRC/gFSM, while that to the FSM(2.7) (2.7 nm diameter) was low at 0.02 gRC/gFSM, suggesting the specific binding of the RC into the 7.9 nm pores of FSM(7.9). An N(2)-adsorption isotherm study indicated the incorporation of the RC into the 7.9 nm pores. The RC inside FSM(7.9) showed absorption spectra in the visible and infrared regions similar to those of the RC in solution, indicating almost no structural changes induced by the adsorption. The RC-FSM(7.9) conjugate showed the high photochemical activity with the increased thermal stability up to 50 degrees C in the measurements by laser spectroscopy. The conjugates rapidly provided electrons to a dye in the outer medium or showed electric current on the ITO electrode upon the illumination. The RC-FSM conjugate will be useful for the construction of artificial photosynthetic systems and new photodevices. PMID:20695584

  18. Light induced transmembrane proton gradient in artificial lipid vesicles reconstituted with photosynthetic reaction centers.

    Science.gov (United States)

    Milano, Francesco; Trotta, Massimo; Dorogi, Márta; Fischer, Béla; Giotta, Livia; Agostiano, Angela; Maróti, Péter; Kálmán, László; Nagy, László

    2012-06-01

    Photosynthetic reaction center (RC) is the minimal nanoscopic photoconverter in the photosynthetic membrane that catalyzes the conversion of solar light to energy readily usable for the metabolism of the living organisms. After electronic excitation the energy of light is converted into chemical potential by the generation of a charge separated state accompanied by intraprotein and ultimately transmembrane proton movements. We designed a system which fulfills the minimum structural and functional requirements to investigate the physico/chemical conditions of the processes: RCs were reconstituted in closed lipid vesicles made of selected lipids entrapping a pH sensitive indicator, and electron donors (cytochrome c₂ and K₄[Fe(CN)₆]) and acceptors (decylubiquinone) were added to sustain the photocycle. Thanks to the low proton permeability of our preparations, we could show the formation of a transmembrane proton gradient under illumination and low buffering conditions directly by measuring proton-related signals simultaneously inside and outside the vesicles. The effect of selected ionophores such as gramicidin, nigericin and valinomycin was used to gain more information on the transmembrane proton gradient driven by the RC photochemistry.

  19. Effects of reaction conditions on cellulose structures synthesized in vitro by bacterial cellulose synthases.

    Science.gov (United States)

    Penttilä, Paavo A; Sugiyama, Junji; Imai, Tomoya

    2016-01-20

    Cellulose was synthesized by cellulose synthases extracted from the Komagataeibacter xylinus (formerly known as Gluconacetobacter xylinus). The effects of temperature and centrifugation of the reaction solution on the synthesis products were investigated. Cellulose with number-average degree of polymerization (DPn) roughly in the range 60-80 and cellulose II crystal structure was produced under all conditions. The amount of cellulose varied with temperature and centrifugation, and the centrifugation at 2000 × g also slightly reduced the DPn. Cellulose production was maximal around the temperature 35 °C and without centrifugation. At higher temperatures and during centrifugation at 2000 × g the proteins started to denature, causing differences also in the morphology of the cellulosic aggregates, as seen with electron microscopy. These observations serve as a basis for discussions about the factors affecting the structure formation and chain length of in vitro synthesized cellulose.

  20. Effects of reaction conditions on cellulose structures synthesized in vitro by bacterial cellulose synthases.

    Science.gov (United States)

    Penttilä, Paavo A; Sugiyama, Junji; Imai, Tomoya

    2016-01-20

    Cellulose was synthesized by cellulose synthases extracted from the Komagataeibacter xylinus (formerly known as Gluconacetobacter xylinus). The effects of temperature and centrifugation of the reaction solution on the synthesis products were investigated. Cellulose with number-average degree of polymerization (DPn) roughly in the range 60-80 and cellulose II crystal structure was produced under all conditions. The amount of cellulose varied with temperature and centrifugation, and the centrifugation at 2000 × g also slightly reduced the DPn. Cellulose production was maximal around the temperature 35 °C and without centrifugation. At higher temperatures and during centrifugation at 2000 × g the proteins started to denature, causing differences also in the morphology of the cellulosic aggregates, as seen with electron microscopy. These observations serve as a basis for discussions about the factors affecting the structure formation and chain length of in vitro synthesized cellulose. PMID:26572398

  1. Report on the consultants' meeting on technical aspects of the co-operation of nuclear reaction data centers

    International Nuclear Information System (INIS)

    The IAEA Nuclear Data Section convenes in annual intervals coordination meetings of the Network of the Nuclear Reaction Data Center. The present meeting dealt with technical matters of the nuclear data compilation and exchange by means of the jointly operated computerized systems CINDA, EXFOR, ENDF and others. Refs, figs and tabs

  2. Duodenal Aspirates for Small Intestine Bacterial Overgrowth: Yield, PPIs, and Outcomes after Treatment at a Tertiary Academic Medical Center

    Directory of Open Access Journals (Sweden)

    Diana L. Franco

    2015-01-01

    Full Text Available Duodenal aspirates are not commonly collected, but they can be easily used in detection of small intestinal bacterial overgrowth (SIBO. Proton pump inhibitor (PPI use has been proposed to contribute to the development of SIBO. We aimed to determine the yield of SIBO-positive cultures detected in duodenal aspirates, the relationship between SIBO and PPI use, and the clinical outcomes of patients identified by this method. In a retrospective study, we analyzed electronic medical records from 1263 consecutive patients undergoing upper endoscopy at a tertiary medical center. Aspirates were collected thought out the third and fourth portions of the duodenum, and cultures were considered to be positive for SIBO if they produced more than 100,000 cfu/mL. Culture analysis of duodenal aspirates identified SIBO in one-third of patients. A significantly higher percentage of patients with SIBO use PPIs than patients without SIBO, indicating a possible association. Similar proportions of patients with SIBO improved whether or not they received antibiotic treatment, calling into question the use of this expensive therapy for this disorder.

  3. Hydration of swelling clay and bacteria interaction. An experimental in situ reaction study; Hydratation des argiles gonflantes et influence des bacteries. Etude experimentale de reaction in situ

    Energy Technology Data Exchange (ETDEWEB)

    Berger, J

    2008-01-15

    -aggregates and bio-films. In confined volume conditions, the presence of bacteria in Na-smectite clay was seen to enhance both the uptake of interlayer water and the amount of externally stored surface and pore water. In this type of compacted smectite, an increase in the total thickness of water layer structures occurs due to bacterial enhancement of sample porosity as seen by combined X-ray diffraction study and CALCMIX profile calculations. In the case of nontronite, additional water was stored as external water indicating a similar enhancement of porosity, but here, the rate of water inflow into the reaction cell decreased, most likely due to clogging of the pores by biofilm. With respect to the application of bentonites as a suitable backfill material in underground waste disposal sites, this study demonstrates that bacterial activity can modify both chemically and physically the properties of the smectite. Even if bacteria are not likely to survive in a hydrated bentonite seal, their effects are considered to be long-term, especially due to bacterially produced substances such as EPS and organic ligands. (author)

  4. Calculated coupling of electron and proton transfer in the photosynthetic reaction center of Rhodopseudomonas viridis.

    Science.gov (United States)

    Lancaster, C R; Michel, H; Honig, B; Gunner, M R

    1996-06-01

    Based on new Rhodopseudomonas (Rp.) viridis reaction center (RC) coordinates with a reliable structure of the secondary acceptor quinone (QB) site, a continuum dielectric model and finite difference technique have been used to identify clusters of electrostatically interacting ionizable residues. Twenty-three residues within a distance of 25 A from QB (QB cluster) have been shown to be strongly electrostatically coupled to QB, either directly or indirectly. An analogous cluster of 24 residues is found to interact with QA (QA cluster). Both clusters extend to the cytoplasmic surface in at least two directions. However, the QB cluster differs from the QA cluster in that it has a surplus of acidic residues, more strong electrostatic interactions, is less solvated, and experiences a strong positive electrostatic field arising from the polypeptide backbone. Consequently, upon reduction of QA or QB, it is the QB cluster, and not the QA cluster, which is responsible for substoichiometric proton uptake at neutral pH. The bulk of the changes in the QB cluster are calculated to be due to the protonation of a tightly coupled cluster of the three Glu residues (L212, H177, and M234) within the QB cluster. If the lifetime of the doubly reduced state QB2- is long enough, Asp M43 and Ser L223 are predicted to also become protonated. The calculated complex titration behavior of the strongly interacting residues of the QB cluster and the resulting electrostatic response to electron transfer may be a common feature in proton-transferring membrane protein complexes. PMID:8744288

  5. The electronic behavior of a photosynthetic reaction center monitored by conductive atomic force microscopy.

    Science.gov (United States)

    Mikayama, Takeshi; Iida, Kouji; Suemori, Yoshiharu; Dewa, Takehisa; Miyashita, Tokuji; Nango, Mamoru; Gardiner, Alastair T; Cogdell, Richard J

    2009-01-01

    The conductivity of a photosynthetic reaction center (RC) from Rhodobacter sphaeroides was measured with conductive atomic force microscopy (CAFM) on SAM-modified Au(111) substrates. 2-mercaptoethanol (2ME), 2-mercaptoacetic acid (MAC), 2-mercaptopyridine (2MP) and 4-mercaptopyridine (4MP) were prepared as SAM materials to investigate the stability and morphology of RCs on the substrate by using near-IR absorption spectroscopy and AFM, respectively. The clear presence of the three well known RC near-IR absorption peaks indicates that the RCs were native on the SAM-modified Au(111). Dense grains with various diameters of 5-20 nm, which corresponded to mixtures of single RCs up to aggregates of 10, were observed in topographs of RCs adsorbed on all the different SAM-modified Au(111) substrates. The size of currents obtained from the RC using a bare conductive cantilever were produced in the following order for SAM molecules: 2MP > 2ME > 4MP > MAC. A clear rectification of this current was observed for the modification of the Au(111) substrate with the pi-conjugated thiol, 2MP, indicating that 2MP was effective in both promoting the specific orientation of the RCs on the electrode and electron injection into the RC. Cyclic voltammetry measurements indicate that the 2MP is better mediator for the electron transfer between a quinone and substrate. The current with 2MP-modified cantilever was twice as high as that obtained with the Au-coated one alone, indicating that 2MP has an important role in lowering the electron injection barrier between special pair side of RC and gold electrode.

  6. Optimizing multi-step B-side charge separation in photosynthetic reaction centers from Rhodobacter capsulatus

    Energy Technology Data Exchange (ETDEWEB)

    Faries, Kaitlyn M. [Washington Univ., St. Louis, MO (United States); Kressel, Lucas L. [Argonne National Lab. (ANL), Argonne, IL (United States); Dylla, Nicholas P. [Argonne National Lab. (ANL), Argonne, IL (United States); Wander, Marc J. [Argonne National Lab. (ANL), Argonne, IL (United States); Hanson, Deborah K. [Argonne National Lab. (ANL), Argonne, IL (United States); Holten, Dewey [Washington Univ., St. Louis, MO (United States); Laible, Philip D. [Argonne National Lab. (ANL), Argonne, IL (United States); Kirmaier, Christine [Washington Univ., St. Louis, MO (United States)

    2016-02-01

    Using high-throughput methods for mutagenesis, protein isolation and charge-separation functionality, we have assayed 40 Rhodobacter capsulatus reaction center (RC) mutants for their P+ QB- yield (P is a dimer of bacteriochlorophylls and Q is a ubiquinone) as produced using the normally inactive B-side cofactors BB and HB (where B is a bacteriochlorophyll and H is a bacteriopheophytin). Two sets of mutants explore all possible residues at M131 (M polypeptide, native residue Val near HB) in tandem with either a fixed His or a fixed Asn at L181 (L polypeptide, native residue Phe near BB). A third set of mutants explores all possible residues at L181 with a fixed Glu at M131 that can form a hydrogen bond to HB. For each set of mutants, the results of a rapid millisecond screening assay that probes the yield of P+ QB- are compared among that set and to the other mutants reported here or previously. For a subset of eight mutants, the rate constants and yields of the individual B-side electron transfer processes are determined via transient absorption measurements spanning 100 fs to 50 μs. The resulting ranking of mutants for their yield of P+ QB- from ultrafast experiments is in good agreement with that obtained from the millisecond screening assay, further validating the efficient, high-throughput screen for B-side transmembrane charge separation. Results from mutants that individually show progress toward optimization of P+ HB- → P+ QB- electron transfer or initial P* → P+ HB- conversion highlight unmet challenges of optimizing both processes simultaneously.

  7. Structural and spectropotentiometric analysis of Blastochloris viridis heterodimer mutant reaction center

    Energy Technology Data Exchange (ETDEWEB)

    Ponomarenko, Nina S.; Li, Liang; Marino, Antony R.; Tereshko, Valentina; Ostafin, Agnes; Popova, Julia A.; Bylina, Edward J.; Ismagilov, Rustem F.; Norris, Jr., James R.; (UC); (Utah)

    2010-07-22

    Heterodimer mutant reaction centers (RCs) of Blastochloris viridis were crystallized using microfluidic technology. In this mutant, a leucine residue replaced the histidine residue which had acted as a fifth ligand to the bacteriochlorophyll (BChl) of the primary electron donor dimer M site (HisM200). With the loss of the histidine-coordinated Mg, one bacteriochlorophyll of the special pair was converted into a bacteriopheophytin (BPhe), and the primary donor became a heterodimer supermolecule. The crystals had dimensions 400 x 100 x 100 {micro}m, belonged to space group P4{sub 3}2{sub 1}2, and were isomorphous to the ones reported earlier for the wild type (WT) strain. The structure was solved to a 2.5 {angstrom} resolution limit. Electron-density maps confirmed the replacement of the histidine residue and the absence of Mg. Structural changes in the heterodimer mutant RC relative to the WT included the absence of the water molecule that is typically positioned between the M side of the primary donor and the accessory BChl, a slight shift in the position of amino acids surrounding the site of the mutation, and the rotation of the M194 phenylalanine. The cytochrome subunit was anchored similarly as in the WT and had no detectable changes in its overall position. The highly conserved tyrosine L162, located between the primary donor and the highest potential heme C{sub 380}, revealed only a minor deviation of its hydroxyl group. Concomitantly to modification of the BChl molecule, the redox potential of the heterodimer primary donor increased relative to that of the WT organism (772 mV vs. 517 mV). The availability of this heterodimer mutant and its crystal structure provides opportunities for investigating changes in light-induced electron transfer that reflect differences in redox cascades.

  8. BACTERIAL AND FUNGAL PATHOGENS IN THE TRANSPLANTATION AND DIALYSIS CENTER. ANALYSIS FOR EIGHTEEN YEARS (1998–2015

    Directory of Open Access Journals (Sweden)

    A. V. Vatazin

    2016-01-01

    Full Text Available Aim: to analyze the dynamics of the microflora and its sensitivity to antibiotics in patients of dialysis and transplantation center.Materials and methods. We have examined the bacteriological test results of 1282 patients with chronic kidney disease, stage 5 (renal transplant recipients and dialysis patients in 1998–2015: 1998–2003 («2003» period, 2008–2011 («2011» period and 2012–2015 («2015» period. Biomaterial: urine, blood, wound effluent, sputum.Results. The incidence (share of all samples of gram «–», gram «+» and fungi was 38, 56, 7% for «2003» period; 48, 69, 13% for «2011» period; 61, 54, 18% for «2015» period. The incidence of gram «–» in blood has significantly increased: 22% in «2003», 13% in «2011», and 45% in «2015», respectively. The incidence of Candida fungi is growing in sputum and urine: 15, 33, 41% and 8, 14, 18% (in 2003, 2011, 2015 respectively. The species composition of the fl ora has also significantly changed. In «2003» the shares of Staphylococcus spp. and Enterococcus spp. were 50 and 33%, in «2015» – 34 and 53% respectively. The shares of E. coli, Klebsiella spp., P. aeruginosa and Acinetobacter spp. were in «2003» 32, 21, 15, 11% respectively, and in «2015» – 17, 32, 9, 22%, respectively. The share of a «problem» genus of Candida: C. glabrata and C. krusei has significantly increased. Their combined share increased from 26 to 38% (2003–2015. There was a significant increase in antibiotic resistance, which is mostly pronounced in Enterococcus spp., Klebsiella spp. and Acinetobacter spp. All gram «+» bacteria in «2003» were susceptible to vancomycin and linezolid, but in «2015» 6% of Enterococcus were resistant to vancomycin. Conclusion. Bacterial profile has significantly changed. Regular analysis of the bacterial fl ora is necessary due to the growing antibiotic resistance. 

  9. Reaction of sulphate radical anion (SO{sub 4}{sup {center_dot}}{sup -}) with cyanuric acid. A potential reaction for its degradation?

    Energy Technology Data Exchange (ETDEWEB)

    Manoj, P.; Varghese, R.; Manoj, V.M.; Aravindakumar, C.T. [Mahatma Gandhi University, School of Chemical Sciences, Kottayam (India)

    2002-01-01

    A novel reaction between sulfate radical anion (SO{sub 4}{sup {center_dot}}{sup -}) and cyanuric acid (CA), a non-degradable end product of the oxidative degradation of the triazine based herbicide, atrazine, is presented using laser flash photolysis and steady state radiolysis techniques at pH 5. A second order rate constant of 1.9x10{sup 7} dm{sup 3} mol{sup -1} s{sup -1} has been determined and the transient intermediate ({lambda}{sub max}=330 nm) is assigned to a radical cation of CA (CA{sup {center_dot}}{sup +}). The degradation profile indicated that about 76% of CA have been decomposed after an absorbed {gamma}-radiation dose of 18 kGy. It is therefore proposed that the reaction of SO{sub 4}{sup {center_dot}}{sup -} could be utilised for the degradation of CA in aqueous medium which is normally stable to any Advanced Oxidation Processes. (author)

  10. Genetic probes of structure/function relationships in the Q{sub B} binding site of the photosynthetic reaction center

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, D.K.; Tiede, D.M.; Nance, S.L.; Chang, Chong-Hwan; Schiffer, M.

    1991-06-25

    In photosynthetic reaction centers, a quinone molecule, Q{sub B}, is the terminal acceptor in light-induced electron transfer. The crystal structure of the reaction center implicates the protonatable amiho acid residues L212Glu and L213Asp in the binding of Q{sub B} to the reaction center and in proton transfer to the anionic forms of Q{sub B} generated by electron transfer from Q{sub A}. Here we report the construction of the double mutant L212Ala-L213Ala by site-specific mutagenesis, and the isolation and preliminary biophysical characterization of revertant and suppressor strains that have regained the ability to grow under photosynthetic conditions. Our results show that neither L212Glu nor L213Asp is essential for efficient light-induced electron or proton transfer in Rhodobacter capsulatus and that second-site mutations, located within the QB binding pocket or at a more distant site, can compensate for mutations at L212 and L213. Acquisition of a single negatively charged residue (at position L213, or on the other side of the binding pocket at position L225) or loss of a positively charged residue (at position M231) is sufficient to restore activity to the complex.

  11. Hydration of swelling clay and bacteria interaction. An experimental in situ reaction study; Hydratation des argiles gonflantes et influence des bacteries. Etude experimentale de reaction in situ

    Energy Technology Data Exchange (ETDEWEB)

    Berger, J

    2008-01-15

    This study reports on the physical-chemical behaviour of swelling di-octahedral clays (smectites) and their interaction with aqueous solutions and bacteria (Shewanella putrefaciens). Experimental results are presented for compacted clays, hydrated under confined volume conditions, using a new type of reaction-cell (the 'wet-cell' of Warr and Hoffman, 2004) that was designed for in situ X-ray diffraction (XRD) measurement. For comparison, dispersed clay systems were studied using standard batch solutions subjected to varying degrees of agitation. The combination of time-dependent in situ XRD measurements with gravimetric measurements and calculated diffraction patterns using the CALCMIX software (Plancon and Drits, 1999) allowed to successful quantification of the dynamics of water uptake and storage. This analytical procedure combined with published water vapour adsorption data enabled determination of the abundance of structured water layers, developed in the interlayer space, and the amount of water contained in different storage sites (interlayers, surfaces and pore spaces). Qualitative information on surface area and textural organization was also estimated based on calculated changes in the average particle thickness and the organization of water layer structures (ordering). Abiotic smectite hydration experiments, using a range of natural and industrial bentonites (SWy-2, IBECO, MX80, TIXOTON), focused on defining the role of the interlayer cation, variable clay packing densities and the ionic strength of the infiltrating solution. The rate of smectite hydration, as expected, was seen to be highly dependent on the type of interlayer cation (enhanced for Ca as opposed to Na) and the ionic strength of solution (enhanced uptake rates with saline solutions, particularly as they infiltrate Na-smectite). A range of dynamic changes in micro textural state occurred as a function of packing density. These changes explain the differences in hydration behaviour

  12. Domino Michael-Michael and Aldol-Aldol Reactions: Diastereoselective Synthesis of Functionalized Cyclohexanone Derivatives Containing Quaternary Carbon Center.

    Science.gov (United States)

    Ghorai, Manas K; Halder, Sandipan; Das, Subhomoy

    2015-10-01

    A simple strategy for the synthesis of highly functionalized cyclohexanone derivatives containing an all-carbon quaternary center from α-(aryl/alkyl)methylidene-β-keto esters or β-diketones via a K-enolate mediated domino Michael-Michael reaction sequence with moderate to good yield and excellent diastereoselectivity (de > 99%) is described. Interestingly, Li-base mediated reaction of α-arylmethylidene-β-diketones affords functionalized 3,5-dihydroxy cyclohexane derivatives as the kinetically controlled products via a domino aldol-aldol reaction sequence with excellent diastereoselectivity. Li-enolates of the β-keto esters or β-diketones undergo facile domino Michael-Michael reaction with nitro-olefins to afford the corresponding nitrocyclohexane derivatives in good yields and excellent diastereoselectivity (de > 99%). The formation of the products and the observed stereoselectivity were explained by plausible mechanisms and supported by extensive computational study. An asymmetric version of the protocol was explored with (L)-menthol derived nonracemic substrates, and the corresponding nonracemic cyclohexanone derivatives containing an all-carbon quaternary center were obtained with excellent stereoselectivity (de, ee > 99%).

  13. Quantitative polymerase chain reaction (PCR) assays for a bacterial thiaminase I gene and the thiaminase-producing bacterium Paenibacillus thiaminolyticus.

    Science.gov (United States)

    Richter, C.A.; Wright-Osment, Maureen K.; Zajicek, J.L.; Honeyfield, D.C.; Tillitt, D.E.

    2009-01-01

    The thiaminase I enzyme produced by the gram-positive bacterium Paenibacillus thiaminolyticus isolated from the viscera of Lake Michigan alewives Alosa pseudoharengus is currently the only defined source of the thiaminase activity linked to thiamine (vitamin B1) deficiency in early mortality syndrome (EMS) in the larvae of Great Lakes salmonines. Diets of alewife or isolated strains of P. thiaminolyticus mixed in a semipurified diet and fed to lake trout Salvelinus namaycush have been shown to produce EMS in fry. We utilized quantitative polymerase chain reaction (Q-PCR) to aid in studies of the sources of P. thiaminolyticus and thiaminase I. Quantitative PCR assays were established to detect the thiaminase I gene of P. thiaminolyticus, the 16S rRNA gene from most species of bacteria, and the 16S rRNA gene specifically from P. thiaminolyticus and a few closely related taxa. The Q-PCR assays are linear over at least six orders of magnitude and can detect the thiaminase I gene of P. thiaminolyticus from as few as 1,000 P. thiaminolyticus cells/g of sample or the Paenibacillus 16S rRNA gene from as few as 100 P. thiaminolyticus cells/g of sample. The initial results from alewife viscera samples with high thiaminase activity yielded unexpectedly low densities of P. thiaminolyticus cells; Paenibacillus thiaminolyticus was detectable in 2 of 6 alewife viscera tested at densities on the order of 100 cells/g out of 100,000,000 total bacterial cells/g. The low numbers of P. thiaminolyticus detected suggest that alewives contain additional non-P. thiaminolyticus sources of thiaminase activity.

  14. Parameterization of the prosthetic redox centers of the bacterial cytochrome bc(1) complex for atomistic molecular dynamics simulations

    DEFF Research Database (Denmark)

    Kaszuba, K.; Postila, P. A.; Cramariuc, O.;

    2013-01-01

    studied in large-scale classical molecular dynamics (MD) simulations. In part, this is due to lack of suitable force field parameters, centered atomic point charges in particular, for the complex's prosthetic redox centers. Accurate redox center charges are needed to depict realistically the inter...

  15. More than Smile Sheets: Rasch Analysis of Training Reactions in a Medical Center

    Science.gov (United States)

    McLinden, Daniel; Boone, William John

    2009-01-01

    Reaction questionnaires administered at the conclusion of a training program are a common method of evaluation. Because such questionnaires are often constructed and analyzed in an ad hoc manner, their usefulness is often difficult to gauge. However, if properly constructed and analyzed, such instruments can help to make clear the strengths and…

  16. Pathogenic reaction of some introduced rice cultivars (lines) to seven pathotypes of bacterial blight in Hangzhou

    Institute of Scientific and Technical Information of China (English)

    SHENYing; ZHUPeiliang; YUANXiaoping

    1993-01-01

    Bacterial blight (BB) caused by Xanthomonas oryzae pv.oryzae (Xoo) is a major rice disease in China. 138 introduced cultivars (lines) were tested on pathogenicity with seven pathotypes of BB at CNRRI Experiment Station during Apt-Oct,1991.

  17. Synthetic Antenna Functioning As Light Harvester in the Whole Visible Region for Enhanced Hybrid Photosynthetic Reaction Centers.

    Science.gov (United States)

    Hassan Omar, Omar; la Gatta, Simona; Tangorra, Rocco Roberto; Milano, Francesco; Ragni, Roberta; Operamolla, Alessandra; Argazzi, Roberto; Chiorboli, Claudio; Agostiano, Angela; Trotta, Massimo; Farinola, Gianluca M

    2016-07-20

    The photosynthetic reaction center (RC) from the Rhodobacter sphaeroides bacterium has been covalently bioconjugated with a NIR-emitting fluorophore (AE800) whose synthesis was specifically tailored to act as artificial antenna harvesting light in the entire visible region. AE800 has a broad absorption spectrum with peaks centered in the absorption gaps of the RC and its emission overlaps the most intense RC absorption bands, ensuring a consistent increase of the protein optical cross section. The covalent hybrid AE800-RC is stable and fully functional. The energy collected by the artificial antenna is transferred to the protein via FRET mechanism, and the hybrid system outperforms by a noteworthy 30% the overall photochemical activity of the native protein under the entire range of visible light. This improvement in the optical characteristic of the photoenzyme demonstrates the effectiveness of the bioconjugation approach as a suitable route to new biohybrid materials for energy conversion, photocatalysis, and biosensing.

  18. Synthetic Antenna Functioning As Light Harvester in the Whole Visible Region for Enhanced Hybrid Photosynthetic Reaction Centers.

    Science.gov (United States)

    Hassan Omar, Omar; la Gatta, Simona; Tangorra, Rocco Roberto; Milano, Francesco; Ragni, Roberta; Operamolla, Alessandra; Argazzi, Roberto; Chiorboli, Claudio; Agostiano, Angela; Trotta, Massimo; Farinola, Gianluca M

    2016-07-20

    The photosynthetic reaction center (RC) from the Rhodobacter sphaeroides bacterium has been covalently bioconjugated with a NIR-emitting fluorophore (AE800) whose synthesis was specifically tailored to act as artificial antenna harvesting light in the entire visible region. AE800 has a broad absorption spectrum with peaks centered in the absorption gaps of the RC and its emission overlaps the most intense RC absorption bands, ensuring a consistent increase of the protein optical cross section. The covalent hybrid AE800-RC is stable and fully functional. The energy collected by the artificial antenna is transferred to the protein via FRET mechanism, and the hybrid system outperforms by a noteworthy 30% the overall photochemical activity of the native protein under the entire range of visible light. This improvement in the optical characteristic of the photoenzyme demonstrates the effectiveness of the bioconjugation approach as a suitable route to new biohybrid materials for energy conversion, photocatalysis, and biosensing. PMID:27245093

  19. Identification of Common Bacterial Pathogens Causing Meningitis in Culture-Negative Cerebrospinal Fluid Samples Using Real-Time Polymerase Chain Reaction.

    Science.gov (United States)

    Khater, Walaa Shawky; Elabd, Safia Hamed

    2016-01-01

    Background. Meningitis is a serious communicable disease with high morbidity and mortality rates. It is an endemic disease in Egypt caused mainly by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. In some settings, bacterial meningitis is documented depending mainly on positive cerebrospinal fluid (CSF) culture results or CSF positive latex agglutination test, missing the important role of prior antimicrobial intake which can yield negative culture and latex agglutination test results. This study aimed to utilize molecular technology in order to diagnose bacterial meningitis in culture-negative CSF samples. Materials and Methods. Forty culture-negative CSF samples from suspected cases of bacterial meningitis were examined by real-time polymerase chain reaction (real-time PCR) for the presence of lytA, bexA, and ctrA genes specific for Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis, respectively. Results. Positive real-time PCR results for Streptococcus pneumoniae were detected in 36 (90%) of culture-negative CSF samples while no positive results for Haemophilus influenzae or Neisseria meningitidis were detected. Four (10%) samples were negative by real-time PCR for all tested organisms. Conclusion. The use of molecular techniques as real-time PCR can provide a valuable addition to the proportion of diagnosed cases of bacterial meningitis especially in settings with high rates of culture-negative results. PMID:27563310

  20. Spin densities from subsystem density-functional theory: Assessment and application to a photosynthetic reaction center complex model

    International Nuclear Information System (INIS)

    Subsystem density-functional theory (DFT) is a powerful and efficient alternative to Kohn-Sham DFT for large systems composed of several weakly interacting subunits. Here, we provide a systematic investigation of the spin-density distributions obtained in subsystem DFT calculations for radicals in explicit environments. This includes a small radical in a solvent shell, a π-stacked guanine-thymine radical cation, and a benchmark application to a model for the special pair radical cation, which is a dimer of bacteriochlorophyll pigments, from the photosynthetic reaction center of purple bacteria. We investigate the differences in the spin densities resulting from subsystem DFT and Kohn-Sham DFT calculations. In these comparisons, we focus on the problem of overdelocalization of spin densities due to the self-interaction error in DFT. It is demonstrated that subsystem DFT can reduce this problem, while it still allows to describe spin-polarization effects crossing the boundaries of the subsystems. In practical calculations of spin densities for radicals in a given environment, it may thus be a pragmatic alternative to Kohn-Sham DFT calculations. In our calculation on the special pair radical cation, we show that the coordinating histidine residues reduce the spin-density asymmetry between the two halves of this system, while inclusion of a larger binding pocket model increases this asymmetry. The unidirectional energy transfer in photosynthetic reaction centers is related to the asymmetry introduced by the protein environment.

  1. Spin densities from subsystem density-functional theory: Assessment and application to a photosynthetic reaction center complex model

    Science.gov (United States)

    Solovyeva, Alisa; Pavanello, Michele; Neugebauer, Johannes

    2012-05-01

    Subsystem density-functional theory (DFT) is a powerful and efficient alternative to Kohn-Sham DFT for large systems composed of several weakly interacting subunits. Here, we provide a systematic investigation of the spin-density distributions obtained in subsystem DFT calculations for radicals in explicit environments. This includes a small radical in a solvent shell, a π-stacked guanine-thymine radical cation, and a benchmark application to a model for the special pair radical cation, which is a dimer of bacteriochlorophyll pigments, from the photosynthetic reaction center of purple bacteria. We investigate the differences in the spin densities resulting from subsystem DFT and Kohn-Sham DFT calculations. In these comparisons, we focus on the problem of overdelocalization of spin densities due to the self-interaction error in DFT. It is demonstrated that subsystem DFT can reduce this problem, while it still allows to describe spin-polarization effects crossing the boundaries of the subsystems. In practical calculations of spin densities for radicals in a given environment, it may thus be a pragmatic alternative to Kohn-Sham DFT calculations. In our calculation on the special pair radical cation, we show that the coordinating histidine residues reduce the spin-density asymmetry between the two halves of this system, while inclusion of a larger binding pocket model increases this asymmetry. The unidirectional energy transfer in photosynthetic reaction centers is related to the asymmetry introduced by the protein environment.

  2. Spin densities from subsystem density-functional theory: Assessment and application to a photosynthetic reaction center complex model

    Energy Technology Data Exchange (ETDEWEB)

    Solovyeva, Alisa [Gorlaeus Laboratories, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands); Technical University Braunschweig, Institute for Physical and Theoretical Chemistry, Hans-Sommer-Str. 10, 38106 Braunschweig (Germany); Pavanello, Michele [Gorlaeus Laboratories, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands); Neugebauer, Johannes [Technical University Braunschweig, Institute for Physical and Theoretical Chemistry, Hans-Sommer-Str. 10, 38106 Braunschweig (Germany)

    2012-05-21

    Subsystem density-functional theory (DFT) is a powerful and efficient alternative to Kohn-Sham DFT for large systems composed of several weakly interacting subunits. Here, we provide a systematic investigation of the spin-density distributions obtained in subsystem DFT calculations for radicals in explicit environments. This includes a small radical in a solvent shell, a {pi}-stacked guanine-thymine radical cation, and a benchmark application to a model for the special pair radical cation, which is a dimer of bacteriochlorophyll pigments, from the photosynthetic reaction center of purple bacteria. We investigate the differences in the spin densities resulting from subsystem DFT and Kohn-Sham DFT calculations. In these comparisons, we focus on the problem of overdelocalization of spin densities due to the self-interaction error in DFT. It is demonstrated that subsystem DFT can reduce this problem, while it still allows to describe spin-polarization effects crossing the boundaries of the subsystems. In practical calculations of spin densities for radicals in a given environment, it may thus be a pragmatic alternative to Kohn-Sham DFT calculations. In our calculation on the special pair radical cation, we show that the coordinating histidine residues reduce the spin-density asymmetry between the two halves of this system, while inclusion of a larger binding pocket model increases this asymmetry. The unidirectional energy transfer in photosynthetic reaction centers is related to the asymmetry introduced by the protein environment.

  3. The functional role of protein dynamics in photosynthetic reaction centers investigated by elastic and quasielastic neutron scattering

    Directory of Open Access Journals (Sweden)

    Pieper Jörg

    2015-01-01

    Full Text Available This short review summarizes our current knowledge about the functional relevance of protein dynamics in photosynthetic reaction centers. In the case of Photosystem II membrane fragments, elastic and quasielastic neutron scattering experiments reveal a dynamical transition at about 240 K corresponding to the activation of picosecond molecular motions. Likewise, a “freezing” of molecular dynamics is observed upon dehydration. Intriguingly, these effects correlate with the pronounced temperature- and hydration-dependence of specific electron transfer steps in Photosystem II indicating that molecular dynamics is an indispensable prerequisite for its function. Thus, electron transfer in Photosystem II appears to be a prototypical example for a dynamics-function correlation. Finally, the laser-neutron pump-probe technique is shown to permit in-situ monitoring of molecular dynamics in specific functional states of a protein in real time.

  4. Quantitation of Pseudomonas aeruginosa in wound biopsy samples: from bacterial culture to rapid `real-time' polymerase chain reaction

    OpenAIRE

    Pirnay, Jean-Paul; Vos, Daniel De; Duinslaeger, Luc; Reper, Pascal; Vandenvelde, Christian; Cornelis, Pierre; Vanderkelen, Alain

    2000-01-01

    Introduction: Early diagnosis of wound colonisation or prediction of wound sepsis provides an opportunity for therapeutic intervention. There is need for qualitative and quantitative tests that are more rapid than bacterial culture. Pseudomonas aeruginosa results in high morbidity and mortality rates, is inherently resistant to common antibiotics, and is increasingly being isolated as a nosocomial pathogen. We developed three PCR-based methods to detect and quantify P aeruginosa in wound biop...

  5. Association of diverse bacterial communities in human bile samples with biliary tract disorders: a survey using culture and polymerase chain reaction-denaturing gradient gel electrophoresis methods.

    Science.gov (United States)

    Tajeddin, E; Sherafat, S J; Majidi, M R S; Alebouyeh, M; Alizadeh, A H M; Zali, M R

    2016-08-01

    Bacterial infection is considered a predisposing factor for disorders of the biliary tract. This study aimed to determine the diversity of bacterial communities in bile samples and their involvement in the occurrence of biliary tract diseases. A total of 102 bile samples were collected during endoscopic retrograde cholangiopancreatography (ERCP). Characterization of bacteria was done using culture and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) methods. Antimicrobial susceptibility of the isolates was determined based on the Clinical and Laboratory Standards Institute (CLSI) guidelines and identity of the nucleotide sequences of differentiated bands from the DGGE gels was determined based on GenBank data. In total, 41.2 % (42/102) of the patients showed bacterial infection in their bile samples. This infection was detected in 21 % (4/19), 45.4 % (5/11), 53.5 % (15/28), and 54.5 % (24/44) of patients with common bile duct stone, microlithiasis, malignancy, and gallbladder stone, respectively. Escherichia coli showed a significant association with gallstones. Polymicrobial infection was detected in 48 % of the patients. While results of the culture method established coexistence of biofilm-forming bacteria (Pseudomonas aeruginosa, E. coli, Klebsiella pneumoniae, Enterococcus spp., and Acinetobacter spp.) in different combinations, the presence of Capnocytophaga spp., Lactococcus spp., Bacillus spp., Staphylococcus haemolyticus, Enterobacter or Citrobacter spp., Morganella spp., Salmonella spp., and Helicobacter pylori was also characterized in these samples by the PCR-DGGE method. Multidrug resistance phenotypes (87.5 %) and resistance to third- and fourth-generation cephalosporins and quinolones were common in these strains, which could evolve through their selection by bile components. Ability for biofilm formation seems to be a need for polymicrobial infection in this organ. PMID:27193890

  6. Does slow energy transfer limit the observed time constant for radical pair formation in photosystem II reaction centers?

    Science.gov (United States)

    Rech, T; Durrant, J R; Joseph, D M; Barber, J; Porter, G; Klug, D R

    1994-12-13

    We have used spectrally photoselective femtosecond transient absorption spectroscopy on photosystem II reaction centers to show that there are at least two pools of chlorin molecules/states which can transfer excitation energy to P680, the primary electron donor in photosystem II. It has previously been shown that one chlorin pool equilibrates with P680 in 100 fs [Durrant et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 11632-11636], and we report here the observation of energy transfer from a second more weakly coupled chlorin pool. The effect of the weakly coupled pool is to increase the apparent time constant for radical pair formation from 21 ps when P680 is selectively excited to 27 ps when the accessory chlorins are excited. We conclude that it is possible to observe both radical pair formation somewhat slowed by an energy transfer step and radical pair formation not limited by this slow energy transfer, depending upon which chromophores are initially excited. These observations provide evidence that when using photoselective excitation of P680, the observed 21 ps time constant for radical pair formation is not limited by a slow energy transfer step. PMID:7993905

  7. Reaction Control System Thruster Cracking Consultation: NASA Engineering and Safety Center (NESC) Materials Super Problem Resolution Team (SPRT) Findings

    Science.gov (United States)

    MacKay, Rebecca A.; Smith, Stephen W.; Shah, Sandeep R.; Piascik, Robert S.

    2005-01-01

    The shuttle orbiter s reaction control system (RCS) primary thruster serial number 120 was found to contain cracks in the counter bores and relief radius after a chamber repair and rejuvenation was performed in April 2004. Relief radius cracking had been observed in the 1970s and 1980s in seven thrusters prior to flight; however, counter bore cracking had never been seen previously in RCS thrusters. Members of the Materials Super Problem Resolution Team (SPRT) of the NASA Engineering and Safety Center (NESC) conducted a detailed review of the relevant literature and of the documentation from the previous RCS thruster failure analyses. It was concluded that the previous failure analyses lacked sufficient documentation to support the conclusions that stress corrosion cracking or hot-salt cracking was the root cause of the thruster cracking and lacked reliable inspection controls to prevent cracked thrusters from entering the fleet. The NESC team identified and performed new materials characterization and mechanical tests. It was determined that the thruster intergranular cracking was due to hydrogen embrittlement and that the cracking was produced during manufacturing as a result of processing the thrusters with fluoride-containing acids. Testing and characterization demonstrated that appreciable environmental crack propagation does not occur after manufacturing.

  8. The Effect of Trimosan© Gel on Pessary-Associated Bacterial Vaginosis: A Multi-Center, Randomized, Controlled Trial

    Science.gov (United States)

    Meriwether, Kate V.; Rogers, Rebecca G.; Craig, Ellen; Peterson, Sean D.; Gutman, Robert E.; Iglesia, Cheryl B.

    2015-01-01

    Objectives Pessaries are important options for women with pelvic floor disorders, but many pessary users experience bacterial vaginosis (BV). The aim of this study was to evaluate the effect of TrimoSan© gel on BV prevalence among pessary users. Study Design Women presenting for a pessary fitting completed questionnaires on vaginal symptoms and hormone therapy (HT) use and underwent a BV® BLUE test and slide collection for BV analysis by Nugent's criteria. Following pessary fitting, women were randomized to either standard pessary care with the use of TrimoSan© placed vaginally twice weekly or to standard pessary care without TrimoSan© gel. Women returned 2 weeks and 3 months later for repeat slide collection for Gram stain, BV® BLUE testing, and completion of questionnaires on vaginal symptoms and desire to continue the pessary. Results There were 184 women randomized after successful fitting (92 to the TrimoSan© group), and 147 (79%) presented for 3 month follow up. Mean age was 56 ± 16 years; patients were mostly Caucasian (57%) or Hispanic (23%) and 36% were using HT. The groups did not differ in the prevalence of BV by Nugent's criteria at 2 weeks (20% TrimoSan© vs 26% no gel, p=0.46) or 3 months (24% TrimoSan© vs 23% no gel, p=0.82), nor did they differ in BV by BV® BLUE testing at 2 weeks (0%TrimoSan©vs 4% no gel, p=0.12) or 3 months (3% TrimoSan© vs 0% no gel, p=0.15). The prevalence of at least one vaginal symptom did not differ between groups at 2 weeks (44% TrimoSan© vs 45% no gel, p=0.98) or 3 months (42% TrimoSan© vs 32% no gel, p=0.30). The TrimoSan© group was equally likely to want to continue their pessary use compared to the standard care group at 2 weeks (90% vs 86%, p=0.64) and 3 months (63% vs 60%, p=0.76). Conclusions TrimoSan© gel in the first 3 months of pessary use does not decrease the prevalence of BV or vaginal symptoms and does not alter the likelihood of a woman desiring to continue pessary use. PMID:25935783

  9. Ultrafast transient absorption studies on photosystem I reaction centers from Chlamydomonas reinhardtii. 2: mutations near the P700 reaction center chlorophylls provide new insight into the nature of the primary electron donor.

    Science.gov (United States)

    Holzwarth, Alfred R; Müller, Marc G; Niklas, Jens; Lubitz, Wolfgang

    2006-01-15

    The energy transfer and charge separation kinetics in several core Photosystem I particles of Chlamydomonas reinhardtii with point mutations around the PA and PB reaction center chlorophylls (Chls) have been studied using ultrafast transient absorption spectroscopy in the femtosecond to nanosecond time range to characterize the influence on the early electron transfer processes. The data have been analyzed in terms of kinetic compartment models. The adequate description of the transient absorption kinetics requires three different radical pairs in the time range up to approximately 100 ps. Also a charge recombination process from the first radical pair back to the excited state is present in all the mutants, as already shown previously for the wild-type (Müller, M. G., J. Niklas, W. Lubitz, and A. R. Holzwarth. 2003. Biophys. J. 85:3899-3922; and Holzwarth, A. R., M. G. Müller, J. Niklas, and W. Lubitz. 2005. J. Phys. Chem. B. 109:5903-59115). In all mutants, the primary charge separation occurs with the same effective rate constant within the error limits as in the wild-type (>350 ns(-1)), which implies an intrinsic rate constant of charge separation of hydrogen bond to the keto carbonyl of Chl PA, only a slight slowing down of the secondary electron transfer is observed. Finally for mutant A-W679A, which has the Trp near the PA Chl replaced, either no pronounced effect or, at best, a slight increase on the secondary electron transfer rate constants is observed. The effective charge recombination rate constant is modified in all mutants to some extent, with the strongest effect observed in mutant B-H656C. Our data strongly suggest that the Chls of the PA and PB pair, constituting what is traditionally called the "primary electron donor P700", are not oxidized in the first electron transfer process, but rather only in the secondary electron transfer step. We thus propose a new electron transfer mechanism for Photosystem I where the accessory Chl(s) function as

  10. Clinical utility of panfungal polymerase chain reaction for the diagnosis of invasive fungal disease: a single center experience.

    Science.gov (United States)

    Trubiano, J A; Dennison, A M; Morrissey, C O; Chua, K Y; Halliday, C L; Chen, S C-A; Spelman, D

    2016-02-01

    The role of panfungal polymerase chain reaction (PCR) assays for diagnosis of invasive fungal disease (IFD) is inadequately defined. We describe the use of an internal transcribed spacer 1 (ITS-1) region-directed panfungal PCR in this context at a tertiary referral transplant center. A retrospective review of patients at Alfred Health, Melbourne, Australia (2009-2014) who had clinical samples referred for panfungal PCR testing was conducted. Baseline patient characteristics, antifungal drug history, fungal culture/histopathology, and radiology results were recorded. For bronchoalveolar lavage (BAL) fluid samples, identification of a fungus other than a Candida spp. was defined as a potential pathogen.Of 138 panfungal PCR tests (108 patients), 41 (30%) were positive for a fungal product. Ninety-seven percent (134/138) of specimens were from immunocompromised hosts. Thirteen percent (19/138) of panfungal PCR positive results were for potential pathogens and potential pathogens were detected more frequently in tissue as compared with BAL (12/13 vs. 6/26; P = .0001). No positive panfungal PCR results were obtained from CSF specimens. If histopathology examination was negative, panfungal PCR identified a potential pathogen in only 12% (11/94) of specimens. For the 20 culture negative/histopathology positive specimens, diagnosis of IFD to causative species level by panfungal PCR occurred in 35% (6/20).Sterile site specimens, in particular tissue, were more frequently panfungal PCR positive for potential pathogens than BAL. The utility of panfungal PCR appears greatest in tissue specimens, as an adjunct to histopathology to improve diagnostic sensitivity and specificity. Based on the results of this study we are now only testing tissue specimens by panfungal PCR.

  11. Cyclotriphosphazene appended porphyrins and fulleropyrrolidine complexes as supramolecular multiple photosynthetic reaction centers: steady and excited states photophysical investigation.

    Science.gov (United States)

    Nair, Vishnu Sukumaran; Pareek, Yogita; Karunakaran, Venugopal; Ravikanth, Mangalampalli; Ajayaghosh, Ayyappanpillai

    2014-06-01

    New multiple photosynthetic reaction centers were constructed from cyclophosphazene decorated multiporphyrin chromophores and a fulleropyrrolidine having a pyridine ligand (FPY). The excited state electron transfer in the self-assembled donor-acceptor assembly was investigated by using steady state absorption and emission, time-resolved emission spectroscopy and nanosecond laser flash photolysis. The effect of metal (Zn(2+)) coordination to porphyrin units in the multiporphyrin arrays on cyclophosphazine scaffold (P3N3Zn) was studied by comparing with metal free porphyrin assembly on a cyclophosphazene scaffold (P3N3). In P3N3Zn, the decrease of absorption and fluorescence intensity and the lowering of the amplitude of longer fluorescence lifetime with increase of FPY concentration reflect the formation of a ground state complex with an association constant of ∼14,910 M(-1). When compared to the metal-free complex P3N3, the metal-coordinated derivative P3N3Zn exhibited shortening of the singlet and triplet state lifetimes and lowering of the singlet and triplet quantum yields. The cause of the decrease of the triplet quantum yields by insertion of zinc metal is discussed along with the possible non-planarity of the porphyrin ring. From the fluorescence lifetime measurements for the P3N3Zn-FPY mixture, it is proposed that self-assembly of the donor-acceptor complex leads to charge separated species with a rate constant of 7.1 × 10(9) s(-1). The decrease of triplet state intensity and lifetime of the P3N3Zn in the P3N3Zn-FPY complex from the nanosecond transient absorption studies support the occurrence of intermolecular electron transfer in the triplet state.

  12. Local electrostatic field induced by the carotenoid bound to the reaction center of the purple photosynthetic bacterium Rhodobacter sphaeroides.

    Science.gov (United States)

    Yanagi, Kazuhiro; Shimizu, Madoka; Hashimoto, Hideki; Gardiner, Alastair T; Roszak, Aleksander W; Cogdell, Richard J

    2005-01-20

    Electroabsorption (EA) spectra were recorded in the region of the reaction center (RC) Qy absorption bands of bacteriochlorophyll (Bchl) and bacteriopheophytin, to investigate the effect of carotenoid (Car) on the electrostatic environment of the RCs of the purple bacterium Rhodobacter (Rb.) sphaeroides. Two different RCs were prepared from Rb. sphaeroides strain R26.1 (R26.1-RC); R26.1 RC lacking Car and a reconstituted RC (R26.1-RC+ Car) prepared by incorporating a synthetic Car (3,4-dihydrospheroidene). Although there were no detectable differences between these two RCs in their near infrared (NIR) absorption spectra at 79 and 293 K, or in their EA spectra at 79 K, significant differences were detected in their EA spectra at 293 K. Three nonlinear optical parameters of each RC were determined in order to evaluate quantitatively these differences; transition dipole-moment polarizability and hyperpolarizability (D factor), the change in polarizability upon photoexcitation (Deltaalpha), and the change in dipole-moment upon photoexcitation (Deltamu). The value of D or Deltaalpha determined for each absorption band of the two RC samples showed similar values at 77 or 293 K. However, the Deltamu values of the special pair Bchls (P) and the monomer Bchls absorption bands showed significant differences between the two RCs at 293 K. X-ray crystallography of the two RCs has revealed that a single molecule of the solubilizing detergent LDAO occupies part of the carotenoid binding site in the absence of a carotenoid. The difference in the value of Deltamu therefore represents the differential effect of the detergent LDAO and the carotenoid on P. The change of electrostatic field around P induced by the presence of Car was determined to be 1.7 x 10(5) [V/cm], corresponding to a approximately 10% change in the electrostatic field around P.

  13. Comparison of bacterial culture and polymerase chain reaction (PCR) for the detection of F. tularensis subsp. holarctica in wild animals.

    Science.gov (United States)

    Sting, Reinhard; Runge, Martin; Eisenberg, Tobias; Braune, Silke; Müller, Wolfgang; Otto, Peter

    2013-01-01

    Detection of the zoonotic pathogen Francisella tularensis subsp. holarctica (EF tularensis) in wild animals with culture techniques as well as polymerase chain reaction were compared and discussed on the basis of the investigation of 60 animals. The samples originated from 55 European brown hares (Lepus europaeus), two red foxes (Vulpes vulpes) and one each from a wild rabbit (Oryctolagus cuniculus), a European beaver (Castor fiber), and a lemur (Lemur catta). When comparing the growth of 28 F. tularensis isolates on the cysteine blood agar and the modified Martin-Lewis-agar used in this study, cultivation was successful for 26 isolates on both media, but for two isolates only on the cysteine blood agar. Out of 43 carcasses 19 tested positive in bacteriological culture and PCR. Two culture positive samples of tonsils originating from foxes could not be confirmed by PCR, although PCR was positive in 22 samples that missed growth of F. tularensis. Comparative studies on cultural detection of E. tularensis were performed on samples of 16 hares from lung, spleen, liver and gut and in one case with a peritoneal swab. In at least one of these localizations cultivation of the pathogen was successful. Detection rate was reduced to 94% (15 of 16 hares) considering only the results of the cultures of the lungs and spleens. For a sensitive and rapid detection of F. tularensis subsp. holarctica, the PCR is a suitable method thereby avoiding hazardous multiplying of the pathogen. However, cultivation of F. tularensis is often a prerequisite for further studies on antibiotic resistance patterns of the pathogen, molecular epidemiological and pathological analyses of tularaemia.

  14. Measurements of the reaction e+e- → μ+μ- at center-of-mass energies in the range 6.2--7.4 GeV

    International Nuclear Information System (INIS)

    Measurements of the cross section for the muon-pair-annihilation reaction e+e- → μ+μ-, relative to Bhabha scattering at 40, are reported at center-of-mass energies in the range 6.2--7.4 GeV. These measurements provide a fundamental test of quantum electrodynamics (QED) for timelike values of the invariant four-momentum transfer q2 as high as 54.8 (GeV/c)2, which in this reaction is carried by the photon propagator. The results are in agreement with predictions of QED

  15. Photodamage to Pigment in the Photosystem Ⅱ Reaction Center D1/D2/Cytochrome b559 Complex

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Strong light (800 μmol photons/m2 per s)-induced bleaching of the pigment in the isolated photosystem Ⅱ reaction center (PSII RC) under aerobic conditions (in the absence of electron donors or acceptors) was studied using high-pressure liquid chromatography (HPLC), absorption spectra, 77K fluorescence spectra and resonance Raman spectra. Changes in pigment composition of the PSll RC as determined by HPLC after light treatment were as follows: with increasing illumination time chlorophyll (Chi) a and β-carotene (β-car)content decreased. However, decreases in pheophytin (Pheo) could not be observed because of the mixture of the Pheo formed by degraded chlorophyll possibly. On the basis of absorption spectra, it was determined that, with a short time of illumination, the initial bleaching occurred maximally at 680 nm but that with increasing illumination time there was a blue shift to 678 nm. It was suggested that P680 was destroyed initially, followed by the accessory chlorophyll. The activity of P680 was almost lost after 10 min light treatment. Moreover, the bleaching of Pheo and β-car was observed at the beginning of illumination.After illumination, the fluorescence emission intensity changed and the fluorescence maximum blue shifted,showing that energy transfer was disturbed. Resonance Raman spectra of the PSII RC excited at 488.0 and 514.5 nm showed four main bands, peaking at 1 527 cm-1 (υ1), 1 159 cm-1 (υ2), 1 006 cm-1 (υ3), 966 cm-1 (υ4) for 488.0 nm excitation and 1 525 cm-1 (υ1), 1 159 cm-1 (υ2), 1 007 cm-1 (υ3), 968 cm-1 (υ4) for 514.5 nm excitation.It was confirmed that two spectroscopically different β-car molecules exist in the PSII RC. After light treatment for 20 min, band positions and bandwidths were unchanged. This indicates that carotenoid configuration is not the parameter that regulates photoprotection in the PSII RC.

  16. Site Energies of Active and Inactive Pheophytins in the Reaction Center of Photosystem II from Chlamydomonas Reinhardtii

    International Nuclear Information System (INIS)

    It is widely accepted that the primary electron acceptor in various Photosystem II (PSII) reaction center (RC) preparations is pheophytin α (Pheo α) within the D1 protein (PheoD1), while PheoD2 (within the D2 protein) is photochemically inactive. The Pheo site energies, however, have remained elusive, due to inherent spectral congestion. While most researchers over the past two decades placed the Qy-states of PheoD1 and PheoD2 bands near 678-684 and 668-672 nm, respectively, recent modeling (Raszewski et al. Biophys. J. 2005, 88, 986-998; Cox et al. J. Phys. Chem. B 2009, 113, 12364-12374) of the electronic structure of the PSII RC reversed the assignment of the active and inactive Pheos, suggesting that the mean site energy of PheoD1 is near 672 nm, whereas PheoD2 (∼677.5 nm) and ChlD1 (∼680 nm) have the lowest energies (i.e., the PheoD2-dominated exciton is the lowest excited state). In contrast, chemical pigment exchange experiments on isolated RCs suggested that both pheophytins have their Qy absorption maxima at 676-680 nm (Germano et al. Biochemistry 2001, 40, 11472-11482; Germano et al. Biophys. J. 2004, 86, 1664-1672). To provide more insight into the site energies of both PheoD1 and PheoD2 (including the corresponding Qx transitions, which are often claimed to be degenerate at 543 nm) and to attest that the above two assignments are most likely incorrect, we studied a large number of isolated RC preparations from spinach and wild-type Chlamydomonas reinhardtii (at different levels of intactness) as well as the Chlamydomonas reinhardtii mutant (D2-L209H), in which the active branch PheoD1 is genetically replaced with chlorophyll α (Chl α). We show that the Qx-/Qy-region site energies of PheoD1 and PheoD2 are ∼545/680 nm and ∼541.5/670 nm, respectively, in good agreement with our previous assignment (Jankowiak et al. J. Phys. Chem. B 2002, 106, 8803?8814). The latter values should be used to model excitonic structure and excitation energy

  17. Site Energies of Active and Inactive Pheophytins in the Reaction Center of Photosystem II from Chlamydomonas Reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, K.; Neupane, B.; Zazubovich, V.; Sayre, R. T.; Picorel, R.; Seibert, M.; Jankowiak, R.

    2012-03-29

    It is widely accepted that the primary electron acceptor in various Photosystem II (PSII) reaction center (RC) preparations is pheophytin {alpha} (Pheo {alpha}) within the D1 protein (Pheo{sub D1}), while Pheo{sub D2} (within the D2 protein) is photochemically inactive. The Pheo site energies, however, have remained elusive, due to inherent spectral congestion. While most researchers over the past two decades placed the Q{sub y}-states of Pheo{sub D1} and Pheo{sub D2} bands near 678-684 and 668-672 nm, respectively, recent modeling [Raszewski et al. Biophys. J. 2005, 88, 986-998; Cox et al. J. Phys. Chem. B 2009, 113, 12364-12374] of the electronic structure of the PSII RC reversed the assignment of the active and inactive Pheos, suggesting that the mean site energy of Pheo{sub D1} is near 672 nm, whereas Pheo{sub D2} ({approx}677.5 nm) and Chl{sub D1} ({approx}680 nm) have the lowest energies (i.e., the Pheo{sub D2}-dominated exciton is the lowest excited state). In contrast, chemical pigment exchange experiments on isolated RCs suggested that both pheophytins have their Q{sub y} absorption maxima at 676-680 nm [Germano et al. Biochemistry 2001, 40, 11472-11482; Germano et al. Biophys. J. 2004, 86, 1664-1672]. To provide more insight into the site energies of both Pheo{sub D1} and Pheo{sub D2} (including the corresponding Q{sub x} transitions, which are often claimed to be degenerate at 543 nm) and to attest that the above two assignments are most likely incorrect, we studied a large number of isolated RC preparations from spinach and wild-type Chlamydomonas reinhardtii (at different levels of intactness) as well as the Chlamydomonas reinhardtii mutant (D2-L209H), in which the active branch Pheo{sub D1} is genetically replaced with chlorophyll {alpha} (Chl {alpha}). We show that the Q{sub x}-/Q{sub y}-region site energies of Pheo{sub D1} and Pheo{sub D2} are {approx}545/680 nm and {approx}541.5/670 nm, respectively, in good agreement with our previous assignment

  18. Xanthophyll Cycle and Inactivation of Photosystem Ⅱ Reaction Centers Alleviating Reducing Pressure to Photosystem Ⅰ in Morning Glory Leaves under Short-term High Irradiance

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    investigated through chlorophyll fluorescence parameters in morning glory (Ipomoea setosa) leaves, which were dipped into water, dithiothreitol (DTT) and lincomycin (LM), respectively. During the stress, both the xanthophyll cycle and D1 protein turnover could protect PSI from photoinhibition. In DTT leaves, non-photochemical quenching (NPQ) was inhibited greatly and the oxidation level of P700 (P700+) was the lowest one. However, the maximal photochemical efficiency of PSII (Fv/Fm) in DTT leaves was higher than that of LM leaves and was lower than that of control leaves. These results suggested that PSI was more sensitive to the loss of the xanthophyll cycle than PSII under high irradiance. In LM leaves, NPQ was partly inhibited, Fv/Fm was the lowest one among three treatments under high irradiance and P700+ was at a similar level as that of control leaves. These results implied that inactivation of PSII reaction centers could protect PSI from further photoinhibition. Additionally, the lowest of the number of active reaction centers to one inactive reaction center for a PSII cross-section (RC/CSo), maximal trapping rate in a PSII cross-section (TRo/CSo), electron transport in a PSII cross-section (ETo/CSo) and the highest of 1-qP in LM leaves further indicated that severe photoinhibition of PSII in LM leaves was mainly induced by inactivation of PSII reaction centers, which limited electrons transporting to PSI. However, relative to the LM leaves the higher level of RC/CSo, TRo/CSo, Fv/Fm and the lower level of 1-qP in DTT leaves indicated that PSI photoinhibition was mainly induced by the electron accumulation at the PSI acceptor side, which induced the decrease of P700+ under high irradiance.

  19. Measurements of the reaction e+e-→e+e- at center-of-mass energies of 7.0 and 7.4 GeV

    International Nuclear Information System (INIS)

    Measurements of the cross section for the reaction e+e-→e+e- (Bhabha scattering) at angles close to 90degree, relative to Bhabha scattering at 4degree, are reported at center-of-mass energies of 7.0 and 7.4 GeV. The results are in agreement with quantum electrodynamics, and new limits on cutoff parameters for the photon propagator are given

  20. Characterization of hypersensitivity reactions reported among Andrographis paniculata users in Thailand using Health Product Vigilance Center (HPVC) database

    OpenAIRE

    Suwankesawong, Wimon; Saokaew, Surasak; Permsuwan, Unchalee; Chaiyakunapruk, Nathorn

    2014-01-01

    Background Andrographis paniculata (andrographis) is one of the herbal products that are widely used for various indications. Hypersensitivity reactions have been reported among subjects receiving Andrographis paniculata in Thailand. Understanding of characteristics of patients, adverse events, and clinical outcomes is essential for ensuring population safety. This study aimed to describe the characteristics of hypersensitivity reactions reported in patients receiving andrographis containing ...

  1. A Monte Carlo Simulation of a Monomer Dimer CO-O2 Catalytic Reaction on the Surface and Subsurface of a Face-centered Cubic Lattice

    Institute of Scientific and Technical Information of China (English)

    K.Iqbal; A.Basit

    2011-01-01

    @@ The presence of oxygen in the subsurface in monomer-dimer reactions(CO-O2 and NO-CO)is observed experimentally.The effect of subsurface oxygen on a CO-O2 catalytic reaction on a face-centered cubic(FCC)lattice is studied using Monte Carlo simulation.The effect of adding subsurface neighbours on the phase diagram is also extensively explored.It is observed that the subsurface oxygen totally eliminates the typical second order phase transition.It is also shown that the introduction of the diffusion of O atoms and the subsurface of the FCC lattice shifts the single transition point towards the stoichiometric ratio.%The presence of oxygen in the subsurface in monomer-dimer reactions (CO-O2 and NO-CO) is observed experimentally. The effect of subsurface oxygen on a CO-O2 catalytic reaction on a face-centered cubic (FCC) lattice is studied using Monte Carlo simulation. The effect of adding subsurface neighbours on the phase diagram is also extensively explored. It is observed that the subsurface oxygen totally eliminates the typical second order phase transition. It is also shown that the introduction of the diffusion of O atoms and the subsurface of the FCC lattice shifts the single transition point towards the stoichiometric ratio.

  2. Evolution of direct mechanisms with incident energy from the Coulomb-barrier to relativistic energies. - Two-center effects in nucleon transfer between nuclei. - Signatures of nucleon promotion in heavy ion reactions at barrier energies

    International Nuclear Information System (INIS)

    This report contains a review article considering the evolution of direct mechanisms with incident energy in heavy ion reactions and two theoretical articles concerning two-center effects in transfer reactions between heavy ions and the nucleon promotion in heavy ion reactions. See hints under the relevant topics. (HSI)

  3. Etiologia e evolução das meningites bacterianas em centro de pediatria Etiology and evolution of bacterial meningitis in a pediatric center

    Directory of Open Access Journals (Sweden)

    Roberta M.C. Romanelli

    2002-02-01

    Full Text Available Objetivo: determinar a prevalência dos agentes etiológicos das meningites bacterianas em serviço de referência, no atendimento de doenças infecciosas para o estado de Minas Gerais, e verificar a resposta ao tratamento utilizado.Métodos: estudo descritivo em que foram incluídas todas as crianças com diagnóstico provável de meningite, admitidas na instituição no período de junho a novembro/99.Resultados: obteve-se 210 casos de meningite, sendo 111 casos de etiologia bacteriana (52,9%. Destes, 52 casos foram diagnósticos prováveis (por alteração do liquor rotina e 59 com diagnósticos de certeza (por cultura e/ou isolamento de antígeno. Os principais agentes isolados foram, em ordem decrescente, H. influenzae, N. meningitidis e S. pneumoniae. O tratamento inicial para a faixa etária de três meses a cinco anos foi ampicilina e cloranfenicol, sendo posteriormente restrito para penicilina em casos de meningococo e pneumococo, e para cloranfenicol nos casos de H. influenzae. A mudança para antimicrobiano de maior espectro foi realizada com base em dados clínicos ou laboratoriais, não havendo isolamento de microorganismo resistente.Conclusões: o acompanhamento do perfil epidemiológico das meningites deve ser contínuo, e cada serviço deve se basear em dados locais para direcionar a terapia antimicrobiana. A monitorização contínua dos agentes prevalentes em cada instituição e de sua resistência é fundamental para a escolha antimicrobiana, atuando com menor interferência na colonização individual, sem contribuir para a crescente resistência dos agentes responsáveis pelas infecções meníngeas.Objective: to establish the prevalence of the etiological agents of bacterial meningitis in a reference center for the treatment of infectious diseases in the state of Minas Gerais. Methods: descriptive study including all children with probable diagnosis of meningitis between June/1999 and November/1999.Results: there were 210

  4. Probing the Energy Transfer Dynamics of Photosynthetic Reaction Center Complexes Through Hole-Burning and Single-Complex Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Kerry Joseph [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    Photosynthesis is the process by which light energy is used to drive reactions that generate sugars to supply energy for cellular processes. It is one of the most important fundamental biological reactions and occurs in both prokaryotic (e.g. bacteria) and eukaryotic (e.g. plants and algae) organisms. Photosynthesis is also remarkably intricate, requiring the coordination of many different steps and reactions in order to successfully transform absorbed solar energy into a biochemical usable form of energy. However, the net reaction for all photosynthetic organisms can be reduced to the following, deceptively general, equation developed by Van Niel[1] H2 - D + Aimplieshv A - H2 + D where H2-D is the electron donor, e.g. H2O, H2S. A is the electron acceptor, e.g. CO2, and A-H2 is the synthesized sugar. Amazingly, this simple net equation is responsible for creating the oxidizing atmosphere of Earth and the recycling of CO2, both of which are necessary for the sustainment of the global ecosystem.

  5. Measurements of the reaction e+e- → γγ at center-of-mass energies in the range 6.2--7.4 GeV

    International Nuclear Information System (INIS)

    Measurements of the cross section for the pair-annihilation reaction e+e- → γγ at angles close to 90degree, relative to Bhabha scattering at 4degree, are reported at center-of-mass energies in the range 6.2--7.4 GeV. These measurements provide a fundamental test of quantum electrodynamics (QED) for spacelike values of the invariant four-momentum transfer q2 as high at -40 (GeV/c)2, which in this reaction is carried by the lepton propagator. A principal feature of the detection apparatus is the use of large NaI(Tl) total-absorption spectrometers. The results are in agreement with the predictions of QED

  6. Effective mass distributions for protons, pions and kaons particle combinations (two and three hadrons) for Au-Au reactions at 200 AGeV center of mass energy

    International Nuclear Information System (INIS)

    A preliminary analysis of the effective mass distributions for two and three hadronic combinations including protons, pions and kaons is presented for a number of 798,000 Au-Au reactions at 200 AGeV center of mass energy collected by the BRAHMS Collaboration (RHIC-Brookhaven National Laboratory). Different procedures to detect the classical resonances inside the high level of background were used. Comparisons with simulations of experimental data using UrQMD code are given, too. The strong suppression of the hadronic resonances weights (delta resonance, N*, K*, rho, etc.) could suggest a possible quark-gluon state. (authors)

  7. Spin Trapping of the Phosphorus-centered Radicals Generated from Hydrogen Abstraction Reaction by 2,2-Diphenyl-1-picrylhydrazyl

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Two kinds of the phosphorus-centered radicals produced from hydrogen atom abstraction by2,2-diphenyl-1-picrylhydrazyl (DPPH) were trapped by N-tert-butyl-a-phenylnitrone (PBN) and5,5-dimethyl-l-pyrroline N-oxide (DMPO), and investigated by means of EPR spectroscopy.The spin adducts with a characteristic hyperfine coupling constant(hfcc) caused by a phosphorusatom were observed. Based on the hfcc values caused by the phosphorus and hydrogen atoms,the conformational positions of the adducts trapped by PBN and DMPO are discussed.

  8. Report on the consultants' meeting on co-ordination of the nuclear reaction data centers (technical aspects)

    International Nuclear Information System (INIS)

    The report summarizes the co-ordination meeting of the network of Nuclear Reaction Data Centres organized by the IAEA in 1997. The meeting was attended by technical staff from ten member centres of the network (representing USA, Russia, China, Japan, Hungary, OECD-NEA and IAEA) to discuss technical matters of the nuclear data compilation and exchange by means of the jointly operated computerized systems CINDA, EXFOR, ENDF and others. Observers from Belgium and Ukraine also attended the meeting. The document includes status reports of all centres and selected working papers

  9. Study of the Mn-binding sites in photosystem II using antibodies raised against lumenal regions of the D1 and D2 reaction center proteins

    Energy Technology Data Exchange (ETDEWEB)

    Dalmasso, E.A.

    1992-04-01

    The experiments discussed in this thesis focus on identifying the protein segments or specific amino acids which provide ligands to the Mn cluster of photosystem II (PS II). This Mn cluster plays a central role in the oxygen-evolving complex (OEC) of PS II. The Mn cluster is thought to be bound by lumenal regions of the PS II reaction center proteins known as D1 and D2. First, several peptides were synthesized which correspond to specific lumenal segments of the D1 and D2 proteins. Next, polyclonal antibodies were successfully elicited using three of these peptides. The peptides recognized by these antibodies correspond to protein segments of the spinach reaction center proteins: Ile-321 to Ala-344 of D1 (D1-a), Asp-319 to Arg-334 of D1 (D1-b), and Val-300 to Asn-319 of D2 (D2-a). These antibodies were then used in assays which were developed to structurally or functionally probe the potential Mn-binding regions of the D1 and D2 proteins.

  10. Adverse cutaneous drug reactions: Clinical pattern and causative agents in a tertiary care center in South India

    Directory of Open Access Journals (Sweden)

    Pudukadan David

    2004-01-01

    Full Text Available Background: Adverse cutaneous drug reactions (ACDRs are caused by a wide variety of agents. Aims: Our objective was to ascertain the clinical spectrum of ACDRs and the causative drugs in this part of India and to find any risk factors. Methods: Ninety patients with adverse cutaneous drug reactions were recruited for this study during 2001-2003. Hematological and biochemical investigations were done in all of them. The VDRL and HIV (ELISA tests were performed where the underlying risk factors were present. Patch testing, intradermal testing and oral provocation tests were done wherever feasible. Results: The mean age of the patients with cutaneous drug eruptions was 37.06 years. Most of them (52.2% were in the age group of 20-39 years. The male to female ratio was 0.87: 1. The most common eruptions observed were fixed drug eruption (31.1% and maculopapular rash (12.2%, and the most common causes were co-trimoxazole (22.2% and dapsone (17.7%. Conclusion: The pattern of ACDRs and the drugs causing them is remarkably different in our population. Knowledge of these drug eruptions, the causative drugs and the prognostic indicators is essential for the clinician.

  11. Regulated-stereoselective construction of thirteen stereogenic centers necessary for the frame of (+)-discodermolide, based on iterative Lewis acid-promoted aldol reactions.

    Science.gov (United States)

    Kiyooka, Syun-ichi; Shahid, Kazi Abdus; Goto, Fumitaka; Okazaki, Momotoshi; Shuto, Yoshihiro

    2003-10-17

    The segments C(1)-C(13) and C(15)-C(21) containing the 13 stereogenic centers required for the frame of (+)-discodermolide were synthesized in good to excellent enantio- and diastereoselectivities from a common racemic aldehyde, derived from 2-methyl-1,3-propanediol. The enantioselective aldol reactions of the racemic aldehyde with a silylketene acetal, derived from ethyl 2-bromopropionate, in the presence of chiral oxazaborolidinones, prepared in situ with N-p-toluenesulfonyl-(R)- and -(S)-valine and BH(3).THF, proceeded under kinetic control to give the stereotriads with a high degree of enantioselectivity. Enantioselective (chiral borane) and diastereoselective (BF(3).OEt(2) and TiCl(4)) aldol reactions with the silylketene acetal, coupled with diastereoselective radical debrominations (Bu(3)SnH, Et(3)B, with or without MgBr(2)), were used iteratively. This aldol reaction strategy for the construction of the polypropionate frame dramatically shortened the steps needed for the construction of the final segments.

  12. Theoretical studies on the influence of molecular interactions on the mechanism of electron transfer in photosynthetic reaction center of Rps. viridis

    Institute of Scientific and Technical Information of China (English)

    XU; Hong(徐红); ZHANG; Rubo(张汝波); QU; Zhengwang(屈正旺); ZHANG; Xingkang(张兴康); ZHANG; Qiyuan(张启元)

    2002-01-01

    Based on the QM/MM optimized X-ray crystal structure of the photosynthetic reaction center (PRC) of purple bacteria Rhodopseudomonas (Rps.) viridis, quantum chemistry density functional method (DFT, B3LYP/6-31G) has been performed to study the interactions between the pigment molecules and either the surrounded amino acid residues or water molecules that are either axially coordinated or hydrogen bonded with the pigment molecules, leading to an explanation of the mechanism of the primary electron-transfer (ET) reactions in the PRC. Results show that the axial coordination of amino acid residues greatly raises the ELUMO of pigment molecules and it is important for the possibility of ET to take place. Different hydrogen bonds between amino acid residues, water molecules and pigment molecules decrease the ELUMO of the pigment molecules to different extents. It is crucial for the ET taking place from excited P along L branch and sustains that the ET is a one-step reaction without through accessory bacteriochlorophyll (ABChl b). It is insufficient to treat the whole protein surrounding as a homogeneous dielectric medium.

  13. Associação entre reação hansênica após alta e a carga bacilar avaliada utilizando sorologia anti PGL-I e baciloscopia Association between leprosy reactions after treatment and bacterial load evaluated using anti PGL-I serology and bacilloscopy

    Directory of Open Access Journals (Sweden)

    Maria de Fátima de Medeiros Brito

    2008-01-01

    Full Text Available As reações hansênicas são fenômenos imuno inflamatórios que ocorrem durante a evolução da hanseníase. Atualmente com os critérios de finalização de tratamento esta intercorrência pode ser observada após a alta da poliquimioterapia. Trata-se de um estudo caso-controle onde foram comparados, laboratorialmente, os casos de reação hansênica após alta da poliquimioterapia multibacilar (PQT/MB com o grupo controle para analisar a possível associação entre a reação hansênica após alta e a carga bacilar, utilizando o ML Flow, teste sorológico para detecção de anticorpos contra o Mycobacterium leprae, e os resultados das baciloscopias cutâneas. O estudo foi realizado em dois serviços de referência na cidade de Recife - Pernambuco - Brasil, onde participaram 208 pacientes. Os resultados encontrados indicam que a reação após alta está estatisticamente associada à carga bacilar através da positividade do teste sorológico após alta. Conclui-se que existem fatores de riscos comuns entre a recidiva e a reação após alta.Leprosy (Hansen's disease, HD reactions are immune-inflammatory phenomena that occur during the evolution of the disease. Given the current criteria for treatment of the disease, this event is often observed after the patient has been released from treatment (RFT from multi-drug therapy (MDT. A case-control study was conducted comparing laboratory results of cases of leprosy reactions after RFT from multibacillary MDT (MDT/MB with a control group to analyze the possible association between posttreatment reactions and bacterial load using the ML Flow serological test for detection of antibodies to Mycobacterium leprae and the results of bacilloscopic skin smears. The study was conducted in two reference centers in Recife, Pernambuco State, Brazil, involving 208 patients. The results obtained indicate that posttreatment reaction is statistically associated with bacterial load through positive serology post

  14. Photosynthetic reaction center functionalized nano-composite films: effective strategies for probing and exploiting the photo-induced electron transfer of photosensitive membrane protein.

    Science.gov (United States)

    Lu, Yidong; Xu, Jingjing; Liu, Baohong; Kong, Jilie

    2007-02-15

    Photosynthetic reaction center (RC), a robust transmembrane pigment-protein complex, works as the crucial component participating the primary event of the photo-electrochemical conversion in bacteria. Sparked by the high photo-induced charge separation yield (ca. 100%) of RC, great interests have been aroused to fabricate versatile RC-functionalized nano-composite films for exploring the initial photosynthetic electron transfer (ET) of RC, and thus exploiting well-designed bio-photoelectric converters. In this review, we classify and summarize the current status about the concepts and methods of constructing RC-immobilized nano-composite films or devices for probing the photo-induced ET, and applying to novel bioelectronics if it is possible.

  15. Involvement of DEG5 and DEG8 proteases in the turnover of the photosystem II reaction center D1 protein under heat stress in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    SUN XuWu; WANG LiYuan; ZHANG LiXin

    2007-01-01

    Deg5,deg8 and the double mutant,deg5deg8 of Arabidopsis thaliana were used to study the physiological role of the DEG proteases in the repair cycle of photosystem II (PSII) under heat stress. PSII activity in deg mutants showed increased sensitivity to heat stress,and the extent of this effect was greater in the double mutant,deg5deg8,than in the single mutants,deg5 and deg8. Degradation of the D1 protein was slower in the mutants than in the WT plants. Furthermore,the levels of other PSII reaction center proteins tested remained relatively stable in the mutant and WT plants following high-temperature treatment. Thus,our results indicate that DEG5 and DEG8 may have synergistic function in degradation of D1 protein under heat stress.

  16. Orientations of Iron-Sulfur Clusters FA and FB in the Homodimeric Type-I Photosynthetic Reaction Center of Heliobacterium modesticaldum.

    Science.gov (United States)

    Kondo, Toru; Matsuoka, Masahiro; Azai, Chihiro; Itoh, Shigeru; Oh-Oka, Hirozo

    2016-05-12

    Orientations of the FA and FB iron-sulfur (FeS) clusters in a structure-unknown type-I homodimeric heriobacterial reaction center (hRC) were studied in oriented membranes of the thermophilic anaerobic photosynthetic bacterium Heliobacterium modesticaldum by electron paramagnetic resonance (EPR), and compared with those in heterodimeric photosystem I (PS I). The Rieske-type FeS center in the cytochrome b/c complex showed a well-oriented EPR signal. Illumination at 14 K induced an FB(-) signal with g-axes of gz = 2.066, gy = 1.937, and gx = 1.890, tilted at angles of 60°, 60°, and 45°, respectively, with respect to the membrane normal. Chemical reduction with dithionite produced an additional signal of FA(-), which magnetically interacted with FB(-), with gz = 2.046, gy = 1.942, and gx = 1.911 at 30°, 60°, and 90°, respectively. The angles and redox properties of FA(-) and FB(-) in hRC resemble those of FB(-) and FA(-), respectively, in PS I. Therefore, FA and FB in hRC, named after their g-value similarities, seem to be located like FB and FA, not like FA and FB, respectively, in PS I. The reducing side of hRC could resemble those in PS I, if the names of FA and FB are interchanged with each other. PMID:27101081

  17. Orientations of Iron-Sulfur Clusters FA and FB in the Homodimeric Type-I Photosynthetic Reaction Center of Heliobacterium modesticaldum.

    Science.gov (United States)

    Kondo, Toru; Matsuoka, Masahiro; Azai, Chihiro; Itoh, Shigeru; Oh-Oka, Hirozo

    2016-05-12

    Orientations of the FA and FB iron-sulfur (FeS) clusters in a structure-unknown type-I homodimeric heriobacterial reaction center (hRC) were studied in oriented membranes of the thermophilic anaerobic photosynthetic bacterium Heliobacterium modesticaldum by electron paramagnetic resonance (EPR), and compared with those in heterodimeric photosystem I (PS I). The Rieske-type FeS center in the cytochrome b/c complex showed a well-oriented EPR signal. Illumination at 14 K induced an FB(-) signal with g-axes of gz = 2.066, gy = 1.937, and gx = 1.890, tilted at angles of 60°, 60°, and 45°, respectively, with respect to the membrane normal. Chemical reduction with dithionite produced an additional signal of FA(-), which magnetically interacted with FB(-), with gz = 2.046, gy = 1.942, and gx = 1.911 at 30°, 60°, and 90°, respectively. The angles and redox properties of FA(-) and FB(-) in hRC resemble those of FB(-) and FA(-), respectively, in PS I. Therefore, FA and FB in hRC, named after their g-value similarities, seem to be located like FB and FA, not like FA and FB, respectively, in PS I. The reducing side of hRC could resemble those in PS I, if the names of FA and FB are interchanged with each other.

  18. Variance-corrected Michaelis-Menten equation predicts transient rates of single-enzyme reactions and response times in bacterial gene-regulation

    CERN Document Server

    Pulkkinen, O

    2016-01-01

    Many chemical reactions in biological cells occur at very low concentrations of constituent molecules. Thus, transcriptional gene-regulation is often controlled by poorly expressed transcription-factors, such as E.coli lac repressor with few tens of copies. Here we study the effects of inherent concentration fluctuations of substrate-molecules on the seminal Michaelis-Menten scheme of biochemical reactions. We present a universal correction to the Michaelis-Menten equation for the reaction-rates. The relevance and validity of this correction for enzymatic reactions and intracellular gene-regulation is demonstrated. Our analytical theory and simulation results confirm that the proposed variance-corrected Michaelis-Menten equation predicts the rate of reactions with remarkable accuracy even in the presence of large non-equilibrium concentration fluctuations. The major advantage of our approach is that it involves only the mean and variance of the substrate-molecule concentration. Our theory is therefore accessi...

  19. Seizures Complicating Bacterial Meningitis

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-09-01

    Full Text Available The clinical data of 116 patients, 1 month to <5 years of age, admitted for bacterial meningitis, and grouped according to those with and without seizures during hospitalization, were compared in a study at Buddhist Dalin Tzu Chi General Hospital, Chang Gung Memorial Hospital and other centers in Taiwan.

  20. Using the polymerase chain reaction coupled with denaturing gradient gel electrophoresis to investigate the association between bacterial translocation and systemic inflammatory response syndrome in predicted acute severe pancreatitis

    Institute of Scientific and Technical Information of China (English)

    Callum B Pearce; Vitaly Zinkevich; Iwona Beech; Viera Funjika; Ana Garcia Ruiz; Afraa Aladawi; Hamish D Duncan

    2005-01-01

    AIM: To investigate the use of PCR and DGGE to investigate the association between bacterial translocation and systemic inflammatory response syndrome in predicted severe AP.METHODS: Patients with biochemical and clinical evidence of acute pancreatitis and an APACHE Ⅱ score ≥8 were enrolled. PCR and DGGE were employed to detect bacterial translocation in blood samples collected on d1,3, and 8 after the admission. Standard microbial blood cultures were taken when there was clinical evidence of sepsis or when felt to be clinically indicated by the supervising team.RESULTS: Six patients were included. Of all the patients investigated, only one developed septic complications;the others had uneventful illness. Bacteria were detected using PCR in 4 of the 17 collected blood samples. The patient with sepsis was PCR-positive in two samples (taken on d 1 and 3), despite three negative blood cultures. Using DGGE and specific primers, the bacteria in all blood specimens which tested positive for the presence of bacterial DNA were identified as E coli.CONCLUSION: Our study confirmed thatunlike traditional microbiological techniques, PCR can detect the presence of bacteria in the blood of patients with severe AP. Therefore, this latter method in conjunction with DGGE is potentially an extremely useful tool in predicting septic morbidity and evaluating patients with the disease. Further research using increased numbers of patients, in particular those patients with necrosis and sepsis, is required to assess the reliability of PCR and DGGE in the rapid diagnosis of infection in AP.

  1. Pattern of Adverse Drug Reactions in Children Attending the Department of Pediatrics in a Tertiary Care Center: A Prospective Observational Study

    Science.gov (United States)

    Digra, Kishour Kumar; Pandita, Aakash; Saini, GS; Bharti, Rajni

    2015-01-01

    AIM To study the pattern of various adverse drug reactions (ADRs) occurring in children attending the Department of Pediatrics, SMGS Hospital, Jammu over 1 year. SUBJECTS AND METHODS This was a prospective study, with study population of patients attending Department of Pediatrics over a period of 1 year. A structured format was used to enroll the participants. A pilot study was conducted to test the suitability of the format and feasibility of the study. The study was carried out to review various pattern of ADRs by using the Naranjo probability scale, and severity was assessed by using the Hartwig severity scale. ADRs were classified according to the classification used by the Adverse Drug Reaction Monitoring Center, Central Drugs Standard Control Organization, New Delhi, India. RESULTS In the present study, 104 patients were found to have developed acute drug reactions. Among these, 83.6% were type B, 14.42% type A, and 1.92% were type U. Furthermore, 25.96% ADRs were due to anticonvulsants, followed by antibiotics (22.11%), antipyretics (11.53%), vaccination (8.65%), steroids (6.73%), decongestants (5.67%), snake antivenom and antiemetics (3.84%), and fluids, insulin, and antacids (1.92%). The patients’ dermatological system was involved in 67.30%, followed by the central nervous system (CNS) in 11.53% patients. Renal system was involved in 6.73% patients. Cardiac, musculoskeletal, metabolic, and other systems were involved in 4.80%, 3.84%, 2.88%, and 0.96%, respectively. According to the Hartwig severity scale of ADRs, 64.4% patients had moderate ADRs, 29.8% patients had severe ADRs, and 5.76% had mild ADRs. In the present study, 64.4% patients expressed moderate severity, whereas 29.8% expressed high severity and 5.76% expressed mild ADRs. CONCLUSION ADRs were seen in 71% of the patients between 1 and 5 years of age, 26% in the age group of 5–10 years, and 3% were more than 10 years old. Anticonvulsants (25.96%) and antibiotics (22.11%) were responsible

  2. Mimicking Primitive Photobacteria: Sustainable Hydrogen Evolution Based on Peptide-Porphyrin Co-Assemblies with a Self-Mineralized Reaction Center.

    Science.gov (United States)

    Liu, Kai; Xing, Ruirui; Li, Yongxin; Zou, Qianli; Möhwald, Helmuth; Yan, Xuehai

    2016-09-26

    Molecular evolution, with self-organization of simple molecules towards complex functional systems, provides a new strategy for biomimetic architectonics and perspectives for understanding the complex processes of life. However, there remain many challenges to fabrication of systems comprising different types of units, which interact with one another to perform desired functions. Challenges arise from a lack of stability, dynamic properties, and functionalities that reconcile with a given environment. A co-assembling fiber system composed of simple peptide and porphyrin is presented. This material is considered a prebiotic assembly of molecules that can be rather stable and flexibly self-functionalized with the assistance of visible light in a "prebiotic soup"; acidic (pH 2), hot (70 °C), and mineral-containing (Na(+) , Ti(4+) , Pt(2+) , and so forth) water. The co-assembled peptide-porphyrin fiber, with self-mineralized reaction centers, may serve as a primitive photobacteria-like cellular model to achieve light harvesting, energy transfer, and ultimately sustainable hydrogen evolution. PMID:27585308

  3. Novel Evidence for a Reversible Dissociation of Light-harvesting Complex Ⅱ from Photosystem Ⅱ Reaction Center Complex Induced by Saturating Light Illumination in Soybean Leaves

    Institute of Scientific and Technical Information of China (English)

    Yi Liao; Da-Quan Xu

    2007-01-01

    After saturating light illumination for 3 h the potential photochemical efficiency of photosystem Ⅱ (PSⅡ) (Fv/Fm, the ratio of variable to maximal fluorescence) decreased markedly and recovered basically to the level before saturating light illumination after dark recovery for 3 h in both soybean and wheat leaves, indicating that the decline in Fv/Fm is a reversible down-regulation. Also, the saturating light illumination led to significant decreases in the low temperature (77 K) chlorophyll fluorescence parameters F685 (chlorophyll a fluorescence peaked at 685 nm ) and F685/F735 (F735, chlorophyll a fluorescence peaked at 735 nm) in soybean leaves but not in wheat leaves. Moreover,trypsin (a protease) treatment resulted in a remarkable decrease in the amounts of PsbS protein (a nuclear gene psbS-encoded 22 kDa protein) in the thylakoids from saturating light-illuminated (SI), but not in those from darkadapted (DT) and dark-recovered (DRT) soybean leaves. However, the treatment did not cause such a decrease in amounts of the PsbS protein in the thylakoids from saturating light-illuminated wheat leaves. These results support the conclusion that saturating light illumination induces a reversible dissociation of some light-harvesting complex Ⅱ (LHCⅡ) from PSⅡ reaction center complex in soybean leaf but not in wheat leaf.

  4. Impact of rapid detection of viral and atypical bacterial pathogens by real-time polymerase chain reaction for patients with lower respiratory tract infection

    NARCIS (Netherlands)

    Oosterheert, Jan Jelrik; van Loon, Anton M; Schuurman, Rob; Hoepelman, Andy I M; Hak, Eelko; Thijsen, Steven; Nossent, George; Schneider, Margriet M E; Hustinx, Willem M N; Bonten, Marc J M

    2005-01-01

    BACKGROUND: Rapid diagnostic tests with a high sensitivity for lower respiratory tract infection (LRTI) could lead to improved patient care and reduce unnecessary antibiotic use and associated costs. Diagnostic yields, feasibility, and costs of real-time polymerase chain reaction (PCR) of nasopharyn

  5. Kinetic modeling of exciton migration in photosynthetic systems. 2. Simulations of excitation dynamics in two-dimensional photosystem I core antenna/reaction center complexes.

    Science.gov (United States)

    Trinkunas, G; Holzwarth, A R

    1994-02-01

    Kinetic modeling of the exciton migration in the cyanobacterial photosystem I core complex from Synechococcus sp. was performed by an exact solution of the Pauli master equation for exciton motion. A square two-dimensional 10 x 10 pigment lattice and a Förster dipole-dipole coupling between chromophores was assumed. We calculated decay-associated spectra and lifetimes and compared them to the corresponding experimental data from picosecond fluorescence and transient absorption obtained by global analysis. Seven spectral chlorophyll(Chl) forms, identical in shape but shifted in their absorption maximums, were used to describe the non-homogeneous broadening of the PS I-100 particle absorption spectrum. The optimized Chl lattice arrangement best reproducing the experimental decay-associated spectra as well as the steady-state fluorescence spectrum indicated the long-wavelength-absorbing Chls forming a cluster in the corner of the lattice with the reaction center (RC) placed apart at a distance of two lattice constants. The variable parameters, i.e., the charge separation rate in the RC and the lattice constant a, were found to be optimal at kRC = 2.3 ps-1 and a = 1.14 nm, respectively. The surprising conclusions of the simulations is that Chls with absorption maxima as long a 724 nm have to be taken into account to describe the time-resolved spectra of this PS I particle properly. The dependencies of the exciton decay in the model PS I particle on the excitation wavelength and on the temperature are discussed. We also show that the excited state decay of similar PS I particles that lack the long-wavelength absorbing Chls is nearly mono-exponential. Various critical factors that limit the general reliability of the conclusions of such simulations are discussed in detail. PMID:8161695

  6. Protein-matrix coupling/uncoupling in "dry" systems of photosynthetic reaction center embedded in trehalose/sucrose: the origin of trehalose peculiarity.

    Science.gov (United States)

    Francia, Francesco; Dezi, Manuela; Mallardi, Antonia; Palazzo, Gerardo; Cordone, Lorenzo; Venturoli, Giovanni

    2008-08-01

    Trehalose is a nonreducing disaccharide of glucose found in organisms, which can survive adverse conditions such as extreme drought and high temperatures. Furthermore, isolated structures, as enzymes or liposomes, embedded in trehalose are preserved against stressing conditions [see, e.g., Crowe, L. M. Comp. Biochem. Physiol. A 2002, 131, 505-513]. Among other hypotheses, such protective effect has been suggested to stem, in the case of proteins, from the formation of a water-mediated, hydrogen bond network, which anchors the protein surface to the water-sugar matrix, thus coupling the internal degrees of freedom of the biomolecule to those of the surroundings [Giuffrida, S.; et al. J. Phys. Chem. B 2003, 107, 13211-13217]. Analogous protective effect is also accomplished by other saccharides, although with a lower efficiency. Here, we studied the recombination kinetics of the primary, light-induced charge separated state (P(+)Q(A)(-)) and the thermal stability of the photosynthetic reaction center (RC) of Rhodobacter sphaeroides in trehalose-water and in sucrose-water matrixes of decreasing water content. Our data show that, in sucrose, at variance with trehalose, the system undergoes a "nanophase separation" when the water/sugar mole fraction is lower than the threshold level approximately 0.8. We rationalize this result assuming that the hydrogen bond network, which anchors the RC surface to its surrounding, is formed in trehalose but not in sucrose. We suggest that both the couplings, in the case of trehalose, and the nanophase separation, in the case of sucrose, start at low water content when the components of the system enter in competition for the residual water.

  7. Calculation of Transactinide Homolog Isotope Production Reactions Possible with the Center for Accelerator Mass Spectrometry (CAMS) at Lawrence Livermore National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Moody, K J; Shaughnessy, D A; Gostic, J M

    2011-11-29

    The LLNL heavy element group has been investigating the chemical properties of the heaviest elements over the past several years. The properties of the transactinides (elements with Z > 103) are often unknown due to their low production rates and short half-lives, which require lengthy cyclotron irradiations in order to make enough atoms for statistically significant evaluations of their chemistry. In addition, automated chemical methods are often required to perform consistent and rapid chemical separations on the order of minutes for the duration of the experiment, which can last from weeks to months. Separation methods can include extraction chromatography, liquid-liquid extraction, or gas-phase chromatography. Before a lengthy transactinide experiment can be performed at an accelerator, a large amount of preparatory work must be done both to ensure the successful application of the chosen chemical system to the transactinide chemistry problem being addressed, and to evaluate the behavior of the lighter elemental homologs in the same chemical system. Since transactinide chemistry is literally performed on one single atom, its chemical properties cannot be determined from bulk chemical matrices, but instead must be inferred from the behavior of the lighter elements that occur in its chemical group and in those of its neighboring elements. By first studying the lighter group homologs in a particular chemical system, when the same system is applied to the transactinide element under investigation, its decay properties can be directly compared to those of the homologues, thereby allowing an inference of its own chemistry. The Center for Accelerator Mass Spectrometry (CAMS) at Lawrence Livermore National Laboratory (LLNL) includes a 1 MV Tandem accelerator, capable of accelerating light ions such as protons to energies of roughly 15 MeV. By using the CAMS beamline, tracers of transactinide homolog elements can be produced both for development of chemical systems and

  8. Bacterial Vaginosis

    Science.gov (United States)

    ... 586. Related Content STDs during Pregnancy Fact Sheet Pregnancy and HIV, Viral Hepatitis, and STD Prevention Pelvic Inflammatory Disease ( ... Bacterial Vaginosis (BV) Chlamydia Gonorrhea Genital Herpes Hepatitis HIV/AIDS & STDs Human Papillomavirus ... STDs See Also Pregnancy Reproductive ...

  9. Bacterial Meningitis

    Science.gov (United States)

    ... Schedules Preteen & Teen Vaccines Meningococcal Disease Sepsis Bacterial Meningitis Recommend on Facebook Tweet Share Compartir On this ... serious disease. Laboratory Methods for the Diagnosis of Meningitis This manual summarizes laboratory methods used to isolate, ...

  10. Bacterial carbonatogenesis

    International Nuclear Information System (INIS)

    Several series of experiments in the laboratory as well as in natural conditions teach that the production of carbonate particles by heterotrophic bacteria follows different ways. The 'passive' carbonatogenesis is generated by modifications of the medium that lead to the accumulation of carbonate and bicarbonate ions and to the precipitation of solid particles. The 'active' carbonatogenesis is independent of the metabolic pathways. The carbonate particles are produced by ionic exchanges through the cell membrane following still poorly known mechanisms. Carbonatogenesis appears to be the response of heterotrophic bacterial communities to an enrichment of the milieu in organic matter. The active carbonatogenesis seems to start first. It is followed by the passive one which induces the growth of initially produced particles. The yield of heterotrophic bacterial carbonatogenesis and the amounts of solid carbonates production by bacteria are potentially very high as compared to autotrophic or chemical sedimentation from marine, paralic or continental waters. Furthermore, the bacterial processes are environmentally very ubiquitous; they just require organic matter enrichment. Thus, apart from purely evaporite and autotrophic ones, all Ca and/or Mg carbonates must be considered as from heterotrophic bacterial origin. By the way, the carbon of carbonates comes from primary organic matter. Such considerations ask questions about some interpretations from isotopic data on carbonates. Finally, bacterial heterotrophic carbonatogenesis appears as a fundamental phase in the relationships between atmosphere and lithosphere and in the geo-biological evolution of Earth. (author)

  11. 2014 CHEMICAL REACTIONS AT SURFACES GORDON RESEARCH CONFERENCE AND GORDON RESEARCH SEMINAR (APRIL 28-MAY 3, 2013 - LES DIABLERETS CONFERENCE CENTER, LES DIABLERETS, SWITZERLAND)

    Energy Technology Data Exchange (ETDEWEB)

    Stair, Peter C.

    2013-02-03

    presentations on chemistry at solid and liquid surfaces of relevance to catalysis, synthesis, photochemistry, environmental science, and tribology. Topics include: Fundamental Surface Chemistry; Catalysis; Solid Liquid and Aerosol Interfaces; Surface Photochemistry; Synthesis of Surfaces; Environmental Interfaces; Hot Topics in Surface Chemical Reactions; Tribology; Gas-Surface Scattering and Reactions; Novel Materials and Environments.

  12. The photochemical thiol–ene reaction as a versatile method for the synthesis of glutathione S-conjugates targeting the bacterial potassium efflux system Kef† †Electronic supplementary information (ESI) available: Further experimental details and NMR spectra. See DOI: 10.1039/c5qo00436e Click here for additional data file.

    Science.gov (United States)

    Rasmussen, Tim; Miller, Samantha; Booth, Ian R.

    2016-01-01

    The thiol–ene coupling reaction is emerging as an important conjugation reaction that is suitable for use in a biological setting. Here, we explore the utility of this reaction for the synthesis of glutathione-S-conjugates (GSX) and present a general, operationally simple, protocol with a wide substrate scope. The GSX afforded are an important class of compounds and provide invaluable molecular tools to study glutathione-binding proteins. In this study we apply the diverse library of GSX synthesised to further our understanding of the structural requirements for binding to the glutathione-binding protein, Kef, a bacterial K+ efflux system, found in many bacterial pathogens. This system is vital to the survival of bacteria upon exposure to electrophiles, and plays an essential role in the maintenance of intracellular pH and K+ homeostasis. Consequently, Kef is an appealing target for the development of novel antibacterial drugs. PMID:27110363

  13. Bacterial Adhesion & Blocking Bacterial Adhesion

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk

    2008-01-01

    tract to the microbial flocs in waste water treatment facilities. Microbial biofilms may however also cause a wide range of industrial and medical problems, and have been implicated in a wide range of persistent infectious diseases, including implantassociated microbial infections. Bacterial adhesion...... is the first committing step in biofilm formation, and has therefore been intensely scrutinized. Much however, still remains elusive. Bacterial adhesion is a highly complex process, which is influenced by a variety of factors. In this thesis, a range of physico-chemical, molecular and environmental parameters......, which influence the transition from a planktonic lifestyle to a sessile lifestyle, have been studied. Protein conditioning film formation was found to influence bacterial adhesion and subsequent biofilm formation considerable, and an aqueous extract of fish muscle tissue was shown to significantly...

  14. Bacterial lipases

    NARCIS (Netherlands)

    Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno

    1994-01-01

    Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation, mea

  15. Use of Blood Smears and Dried Blood Spots for Polymerase Chain Reaction-Based Detection and Quantification of Bacterial Infection and Plasmodium falciparum in Severely Ill Febrile African Children.

    Science.gov (United States)

    Wihokhoen, Benchawan; Dondorp, Arjen M; Turner, Paul; Woodrow, Charles J; Imwong, Mallika

    2016-02-01

    Molecular approaches offer a means of testing archived samples stored as dried blood spots in settings where standard blood cultures are not possible. Peripheral blood films are one suggested source of material, although the sensitivity of this approach has not been well defined. Thin blood smears and dried blood spots from a severe pediatric malaria study were assessed using specific polymerase chain reaction (PCR) primers to detect non-typhoidal Salmonella (NTS; MisL gene), Streptococcus pneumoniae (lytA), and Plasmodium falciparum (18S rRNA). Of 16 cases of NTS and S. pneumoniae confirmed on blood culture, none were positive by PCR using DNA extracts from blood films or dried blood spots. In contrast, four of 36 dried blood spots and two of 178 plasma samples were PCR positive for S. pneumoniae, despite negative bacterial blood cultures, suggesting false positives. Quantitative assessment revealed that the effective concentration of P. falciparum DNA in blood films was three log orders of magnitude lower than for dried blood spots. The P. falciparum kelch13 gene could not be amplified from blood films. These findings question the value of blood PCR-based approaches for detection of NTS and S. pneumoniae, and show that stored blood films are an inefficient method of studying P. falciparum.

  16. Bacterial Ecology

    DEFF Research Database (Denmark)

    Fenchel, Tom

    2011-01-01

    Bacterial ecology is concerned with the interactions between bacteria and their biological and nonbiological environments and with the role of bacteria in biogeochemical element cycling. Many fundamental properties of bacteria are consequences of their small size. Thus, they can efficiently exploit...... biogeochemical processes are carried exclusively by bacteria. * Bacteria play an important role in all types of habitats including some that cannot support eukaryotic life....

  17. [Bacterial vaginosis].

    Science.gov (United States)

    Romero Herrero, Daniel; Andreu Domingo, Antonia

    2016-07-01

    Bacterial vaginosis (BV) is the main cause of vaginal dysbacteriosis in the women during the reproductive age. It is an entity in which many studies have focused for years and which is still open for discussion topics. This is due to the diversity of microorganisms that cause it and therefore, its difficult treatment. Bacterial vaginosis is probably the result of vaginal colonization by complex bacterial communities, many of them non-cultivable and with interdependent metabolism where anaerobic populations most likely play an important role in its pathogenesis. The main symptoms are an increase of vaginal discharge and the unpleasant smell of it. It can lead to serious consequences for women, such as an increased risk of contracting sexually transmitted infections including human immunodeficiency virus and upper genital tract and pregnancy complications. Gram stain is the gold standard for microbiological diagnosis of BV, but can also be diagnosed using the Amsel clinical criteria. It should not be considered a sexually transmitted disease but it is highly related to sex. Recurrence is the main problem of medical treatment. Apart from BV, there are other dysbacteriosis less characterized like aerobic vaginitis of which further studies are coming slowly but are achieving more attention and consensus among specialists. PMID:27474242

  18. Intramolecular coupling of eta/sup 2/-iminoacyl groups at group 4 metal centers: a kinetic study of the carbon-carbon double-bond-forming reaction

    Energy Technology Data Exchange (ETDEWEB)

    Durfee, L.D.; McMullen, A.K.; Rothwell, I.P.

    1988-03-02

    The series of bis(eta/sup 2/-iminoacyl) compounds of general formula M(OAr)/sub 2/(eta/sup 2/-R'NCR)/sub 2/ (M = Ti, Zr, Hf; OAr = 2,6-diisopropyl- and 2,6-di-tert-butylphenoxide; R = CH/sub 3/, CH/sub 2/Ph; R' = various substituted phenyls) undergo intramolecular coupling on thermolysis to produce the corresponding enediamide derivatives M(OAr)/sub 2/(R'NC(R) = C(R)NR'). A kinetic study of the reaction in hydrocarbon solvents has shown it to be first order. The reaction is metal dependent with the rate decreasing in the order Ti > Zr > Hf. The rate of the reaction is also dependent on the steric and electronic nature of the nitrogen substituent (R'). The use of the bulky aryl group 2,6-dimethylphenyl retards the reaction, while the use of various 3- and 4-substituted phenyls (3-F, 3-OMe, 4-OMe, 4-Cl, 4-NMe/sub 2/) shows the reaction to be accelerated by electron-withdrawing substituents. A sigma plot based on kinetic data obtained at 67/sup 0/C and 77/sup 0/C yielded rho values of 0.83 (R = 0.97) and 0.84 (R = 0.95), respectively. Both the steric and electronic dependence of the reactivity on the nitrogen substituents is discussed mechanistically and used to rationalize the much more facile intramolecular coupling observed for the related eta/sup 2/-acyl (eta/sup 2/-OCR) functionalities.

  19. Review of Rate Constants and Exploration of Correlations of the Halogen Transfer Reaction of Tri-substituted Carbon-centered Radicals with Molecular Halogens

    Energy Technology Data Exchange (ETDEWEB)

    Poutsma, Marvin L [ORNL

    2012-01-01

    Rate constants for the reaction (R 3C + X2 R 3CX + X ; X = F, Cl, Br, and I) are reviewed. Because of curved Arrhenius plots and negative EX values, empirical structure-reactivity correlations are sought for log kX,298 rather than EX. The well-known poor correlation with measures of reaction enthalpy is demonstrated. The best quantitative predictor for R 3C is p, the sum of the Hammett p constants for the three substituents, R . Electronegative substituents with lone pairs, such as halogen or oxygen, thus appear to destabilize the formation of a polarized pre-reaction complex and/or TS ( +R---X---X -) by -inductive/field electron withdrawal while simultaneously stabilizing them by -resonance electron donation. The best quantitative predictor of the reactivity order of the halogens, I2 > Br2 >> Cl2 F2, is the polarizability of the halogen, (X-X). For the data set of 60 rate constants which span 6.5 orders of magnitude, a modestly successful correlation of log kX,298 is achieved with only two parameters, p and (X-X), with a mean unsigned deviation of 0.59 log units. How much of this residual variance is the result of inaccuracies in the data compared with over-simplification of the correlation approach remains to be seen.

  20. Study of the e+e- → μ+μ-γ reaction at center-of-mass energies between 54 and 64 GeV

    International Nuclear Information System (INIS)

    The cross section and forward-backward muon charge asymmetry for the e+e-→μ+μ-γ reaction were measured to be σ = 2.82 ± 0.35 pb and A = 0.34 ± 0.10 with the VENUS detector at TRISTAN at = 59.2 GeV for an integrated luminosity of 53.5 pb-1. The measured cross section agrees with the theoretical prediction. The asymmetry result is consistent with the electroweak prediction but not with the QED prediction at the level of 2σ. (orig.)

  1. Bacterial Hydrodynamics

    Science.gov (United States)

    Lauga, Eric

    2016-01-01

    Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells, yet they represent the bulk of the world's biomass and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micrometer scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically complex environments. Using hydrodynamics as an organizing framework, I review the biomechanics of bacterial motility and look ahead to future challenges.

  2. Bacterial hydrodynamics

    CERN Document Server

    Lauga, Eric

    2015-01-01

    Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells yet they represent the bulk of the world's biomass, and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds-number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micron scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically-complex environments. Using hydrodynamics as an organizing framework, we review the biomechanics of bacterial motility and look ahead to future challenges.

  3. Reaction of peach tree genotypes to bacterial leaf spot caused by Xanthomonas arboricola pv. prunis Reação de genótipos de pessegueiro a mancha foliar causada por Xanthomonas arboricola pv. pruni

    Directory of Open Access Journals (Sweden)

    José Gilberto Sousa Medeiros

    2011-02-01

    Full Text Available Bacterial leaf spot (BLS, caused by Xanthomonas arboricola pv. pruni, is one of the most important diseases in Brazilian peach [Prunus persica (L. Batsch] orchards and all over the world. The main objective of this study was to evaluate for BLS sensitivity of peach genotypes. Evaluations of thirty genotypes were carried out during the onset of the disease, for incidence, severity and defoliation, in field conditions. Pearson's correlations between the percentage of defoliation and leaf severity rating were performed. Genotypes 'Conserva 985', 'Conserva 871', 'Conserva 1129', and 'Tropic Snow', as resistance sources, and 'Conserva 1153', 'Bonão', 'Conserva 1125', and 'Atenas', as susceptible to BLS, were submitted to detached-leaf bioassay and greenhouse evaluation. The peach genotypes showed different reactions to the BLS, and none was immune to the pathogen. 'Conserva 985' and 'Conserva 1129' confirmed resistance responsiveness while 'Conserva 1153', 'Conserva 1125' and 'Atenas' were found susceptible for the detached-leaf bioassay.A bacteriose foliar causada por Xanthomonas arboricola pv. pruni é uma das mais importantes doenças do pessegueiro [Prunus persica (L. Batsch] no Brasil e no mundo. Avaliou-se a sensibilidade de genótipos de pessegueiro a X. arboricola pv. pruni. Trinta genótipos foram avaliados em campo, quanto à incidência, severidade e desfolha causada pela bactéria. Calculou-se a correlação entre desfolha e severidade da doença. A partir dos resultados obtidos em campo, foram selecionados quatro genótipos resistentes ('Conserva 985', 'Conserva 871', 'Conserva 1129' e 'Tropic Snow' e quatro suscetíveis ('Conserva 1153', 'Bonão', 'Conserva 1125' e 'Atenas' para serem novamente avaliados pelo bioensáio com folhas destacadas e em casa de vegetação. Os genótipos diferiram quanto a reação ao patógeno, não sendo observada imunidade. Confirmou-se a resistência para 'Conserva 985' e 'Conserva 1129' e a

  4. Prevention of bacterial adhesion

    DEFF Research Database (Denmark)

    Klemm, Per; Vejborg, Rebecca Munk; Hancock, Viktoria

    2010-01-01

    Management of bacterial infections is becoming increasingly difficult due to the emergence and increasing prevalence of bacterial pathogens that are resistant to available antibiotics. Conventional antibiotics generally kill bacteria by interfering with vital cellular functions, an approach that ...

  5. Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center, Subproject to Co-PI Eric E. Roden. Final Report

    International Nuclear Information System (INIS)

    This report summarizes research conducted in conjunction with a project entitled 'Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center', which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2.

  6. Comprehensive Structural Characterization of the Bacterial Homospermidine Synthase–an Essential Enzyme of the Polyamine Metabolism

    Science.gov (United States)

    Krossa, Sebastian; Faust, Annette; Ober, Dietrich; Scheidig, Axel J.

    2016-01-01

    The highly conserved bacterial homospermidine synthase (HSS) is a key enzyme of the polyamine metabolism of many proteobacteria including pathogenic strains such as Legionella pneumophila and Pseudomonas aeruginosa; The unique usage of NAD(H) as a prosthetic group is a common feature of bacterial HSS, eukaryotic HSS and deoxyhypusine synthase (DHS). The structure of the bacterial enzyme does not possess a lysine residue in the active center and thus does not form an enzyme-substrate Schiff base intermediate as observed for the DHS. In contrast to the DHS the active site is not formed by the interface of two subunits but resides within one subunit of the bacterial HSS. Crystal structures of Blastochloris viridis HSS (BvHSS) reveal two distinct substrate binding sites, one of which is highly specific for putrescine. BvHSS features a side pocket in the direct vicinity of the active site formed by conserved amino acids and a potential substrate discrimination, guiding, and sensing mechanism. The proposed reaction steps for the catalysis of BvHSS emphasize cation-π interaction through a conserved Trp residue as a key stabilizer of high energetic transition states. PMID:26776105

  7. Comprehensive Structural Characterization of the Bacterial Homospermidine Synthase-an Essential Enzyme of the Polyamine Metabolism.

    Science.gov (United States)

    Krossa, Sebastian; Faust, Annette; Ober, Dietrich; Scheidig, Axel J

    2016-01-01

    The highly conserved bacterial homospermidine synthase (HSS) is a key enzyme of the polyamine metabolism of many proteobacteria including pathogenic strains such as Legionella pneumophila and Pseudomonas aeruginosa; The unique usage of NAD(H) as a prosthetic group is a common feature of bacterial HSS, eukaryotic HSS and deoxyhypusine synthase (DHS). The structure of the bacterial enzyme does not possess a lysine residue in the active center and thus does not form an enzyme-substrate Schiff base intermediate as observed for the DHS. In contrast to the DHS the active site is not formed by the interface of two subunits but resides within one subunit of the bacterial HSS. Crystal structures of Blastochloris viridis HSS (BvHSS) reveal two distinct substrate binding sites, one of which is highly specific for putrescine. BvHSS features a side pocket in the direct vicinity of the active site formed by conserved amino acids and a potential substrate discrimination, guiding, and sensing mechanism. The proposed reaction steps for the catalysis of BvHSS emphasize cation-π interaction through a conserved Trp residue as a key stabilizer of high energetic transition states. PMID:26776105

  8. Hastings Center

    Science.gov (United States)

    ... Public Events October 19, Hastings Center Seminar, Garrison : Human Genetic Engineering: Wh at Can We Do? What Should We ... Public Events October 19, Hastings Center Seminar, Garrison : Human Genetic Engineering: Wh at Can We Do? What Should We ...

  9. Excel Center

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Citigroup,one of the World top 500 companies,has now settled in Excel Center,Financial Street. The opening ceremony of Excel Center and the entry ceremony of Citigroup in the center were held on March 31.Government leaders of Xicheng District,the Excel CEO and the heads of Asia-Pacific Region leaders of Citibank all participated in the ceremony.

  10. Prevention of bacterial adhesion

    DEFF Research Database (Denmark)

    Klemm, Per; Vejborg, Rebecca Munk; Hancock, Viktoria

    2010-01-01

    that imposes selection pressure for resistant bacteria. New approaches are urgently needed. Targeting bacterial virulence functions directly is an attractive alternative. An obvious target is bacterial adhesion. Bacterial adhesion to surfaces is the first step in colonization, invasion, and biofilm formation....... As such, adhesion represents the Achilles heel of crucial pathogenic functions. It follows that interference with adhesion can reduce bacterial virulence. Here, we illustrate this important topic with examples of techniques being developed that can inhibit bacterial adhesion. Some of these will become...

  11. Accelerator Center for Energy Research (ACER)

    Data.gov (United States)

    Federal Laboratory Consortium — The Accelerator Center for Energy Research (ACER) exploits radiation chemistry techniques to study chemical reactions (and other phenomena) by subjecting samples to...

  12. Job center

    Science.gov (United States)

    To better meet the needs of AGU members, a program has been started to increase the effectiveness of the Job Center activity at the Spring and Fall Meetings. As a result, participation in the Job Center at the 1988 AGU Spring Meeting in Baltimore increased substantially compared to previous Spring Meetings. The number of employers, applicants, and interviews scheduled more than doubled compared to the 1987 Spring Job Center.In order to make the meeting Job Centers even better, a survey is being conducted of employers and applicants who participated in the 1988 Spring Job Center. Evaluation of this survey will be useful in continuing increased participation in and the effectiveness of the Job Center at the 1988 Fall Meeting. Past participants and those interested in the future of the Job Center are encouraged to forward comments and suggestions to AGU, Member Programs Division, 2000 Florida Ave., N.W., Washington, DC 20009.

  13. Comparison of a quantitative real-time polymerase chain reaction (qPCR) with conventional PCR, bacterial culture and ELISA for detection of Mycobacterium avium subsp. paratuberculosis infection in sheep showing pathology of Johne's disease.

    Science.gov (United States)

    Sonawane, Ganesh G; Tripathi, Bhupendra N

    2013-12-01

    A quantitative real-time PCR (qPCR) assay employing IS900 gene specific primers of Mycobacterium avium subsp. parartuberculosis (MAP) was compared with conventional PCR, bacterial culture and enzyme-linked immunosorbent assay in 38 sheep showing granulomatous enteritis and lymphadenitis with and without demonstration of acid-fast bacilli (AFB). The lesions were classified as multibacillary (MB) (n = 23), which had diffuse granulomatous lesions with abundant AFB, and paucibacillary (PB) (n = 15), which had focal or multifocal granulomatous lesions with few or no AFB. In the multibacillary group (MB), IS900 PCR detected 19 (82.6%), and qPCR detected all 23 (100%) sheep positive for MAP in the intestine and lymph node tissues. In the paucibacillary group (PB), IS900 PCR detected 2 (13.3%), and qPCR detected all 15 (100%) sheep positive for MAP in tissues. When results of both groups were taken together, IS900 PCR detected 21(55.2%), and qPCR detected all 38 (100%) animals positive for MAP genome either in the intestine or lymph node tissues. On Herrold egg yolk medium, tissues of 14 (60.9%) MB and 5 (33.3%) PB sheep were found to be positive for MAP. Out of 27 sheep (PB = 8, MB = 19) tested by an ELISA, 21 (77.7%) were found to be positive for MAP antibody, of which 25% (2/8) and 100% (19/19) sheep were from PB and MB sheep, respectively. Based on the results of the present study, it was concluded that qPCR was a highly sensitive test in comparison to conventional PCR, ELISA and bacterial culture for the diagnosis of paratuberculosis on infected tissues especially from paucibacillary sheep.

  14. Functional Centering

    CERN Document Server

    Hahn, M

    1996-01-01

    Based on empirical evidence from a free word order language (German) we propose a fundamental revision of the principles guiding the ordering of discourse entities in the forward-looking centers within the centering model. We claim that grammatical role criteria should be replaced by indicators of the functional information structure of the utterances, i.e., the distinction between context-bound and unbound discourse elements. This claim is backed up by an empirical evaluation of functional centering.

  15. Radiation induced centers in irradiated SrB{sub 4}O{sub 7} doped europium and their role in thermally stimulated reactions: Thermally stimulated luminescence, fluorescence and electron paramagnetic resonance studies

    Energy Technology Data Exchange (ETDEWEB)

    Kadam, R.M.; Rajeswari, B., E-mail: rajibala@barc.gov.in; Mohapatra, M.; Porwal, N.K.; Hon, N.S.; Seshagiri, T.K.; Natarajan, V.

    2015-02-15

    Polycrystalline samples of strontium tetraborate (SrB{sub 4}O{sub 7}: SBO) samples doped with different concentrations of europium (0%, 0.05%, 1% and 2%) were synthesized using solid state reaction in air at high temperature. These samples were characterized by X-ray diffraction (XRD), photoluminescence (PL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) techniques. X-ray diffraction studies indicated that SrB{sub 4}O{sub 7} has orthorhombic structure with lattice parameters a=4.237±0.001, b=4.431±0.001, c=10.704±0.010, space group Pnm2{sub i}, Z=2. Thermally Stimulated Luminescence (TSL) investigations on the gamma irradiated sample showed an intense glow peak at 407 K and a weak glow peak at 500 K. The trap parameters namely activation energy (E), order of kinetics (b) and the frequency factor (s) for the main peak at 407 K were determined using the glow curve method. Fluorescence studies showed weak emission at ca 367 nm, which was attributed to f-d transition (4f{sup 6}5d-4f{sup 7}) of Eu{sup 2+} ions in the host lattice, whereas an intense emission in the range 570–650 nm was assigned to {sup 5}D{sub 0}→{sup 7}F{sub J}, J=0,1,2,3 and 4 transition of Eu{sup 3+} in the host lattice. The large value of I{sub (R)}/I{sub (O)} suggested that Eu{sup 3+} ions are situated at sites without center of inversion (lower symmetry) in SBO matrix. EPR studies suggested the formation of boron–oxygen hole trapped center viz, BOHC, electron trapped at oxygen vacancies and some impurity radicals like NO{sub 3}{sup 2−} and CO{sub 2}{sup −} radicals in SBO on irradiation. EPR temperature variation studies in the range 300–475 K on gamma irradiated europium doped samples, suggested a recombination process occurring between boronoxygen hole trapped species and electron trapped species and subsequently energy is transferred to Eu{sup 3+} ion, which on de-excitation yields thermally stimulated luminescence yielding an intense TSL glow

  16. Comprehensive phylogenetic analysis of bacterial reverse transcriptases.

    Directory of Open Access Journals (Sweden)

    Nicolás Toro

    Full Text Available Much less is known about reverse transcriptases (RTs in prokaryotes than in eukaryotes, with most prokaryotic enzymes still uncharacterized. Two surveys involving BLAST searches for RT genes in prokaryotic genomes revealed the presence of large numbers of diverse, uncharacterized RTs and RT-like sequences. Here, using consistent annotation across all sequenced bacterial species from GenBank and other sources via RAST, available from the PATRIC (Pathogenic Resource Integration Center platform, we have compiled the data for currently annotated reverse transcriptases from completely sequenced bacterial genomes. RT sequences are broadly distributed across bacterial phyla, but green sulfur bacteria and cyanobacteria have the highest levels of RT sequence diversity (≤85% identity per genome. By contrast, phylum Actinobacteria, for which a large number of genomes have been sequenced, was found to have a low RT sequence diversity. Phylogenetic analyses revealed that bacterial RTs could be classified into 17 main groups: group II introns, retrons/retron-like RTs, diversity-generating retroelements (DGRs, Abi-like RTs, CRISPR-Cas-associated RTs, group II-like RTs (G2L, and 11 other groups of RTs of unknown function. Proteobacteria had the highest potential functional diversity, as they possessed most of the RT groups. Group II introns and DGRs were the most widely distributed RTs in bacterial phyla. Our results provide insights into bacterial RT phylogeny and the basis for an update of annotation systems based on sequence/domain homology.

  17. Distribution center

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Distribution center is a logistics link fulfill physical distribution as its main functionGenerally speaking, it's a large and hiahly automated center destined to receive goods from various plants and suppliers,take orders,fill them efficiently,and deliver goods to customers as quickly as possible.

  18. Isolation and Identification of Active Compound Cause Light Emmitting of Bacterial Photobacterium phosphoreum Isolated from the Indonesia Jepara Marine Squid

    Directory of Open Access Journals (Sweden)

    Idam Arif

    2005-04-01

    Full Text Available This research carried out to study the bioluminescence process of bacterial Photobacterium phosphoreum isolated from Indonesia marine squid. The method used in the present study involved isolation, purification, electrophoresis, and the absorbance and light intensity measurement. This result show that the luciferace enzyme of bacterial Photobacterium phosphoreum or called LBPP catalyzes the emission of visible light from the reaction of reduced flavin mononucleotide (FMNH2, molecular oxygen (O2, and an aldehyde (RCOH. The electrophoresis data show that LBPP comprised of two different subunits α and βwith 41kD and 38 kD molecular weights. The absorb pattern showed that the bioluminescence process centered around 516 nm and are consistent with the fluorescence data. This result concluded that the excitation state formed after LBPP bind subtracts and the ground state formed after LBPP releases product and visible light.

  19. 牙周牙髓联合病变菌群的PCR-DGGE分析%Bacterial analysis of combined periodontal-endodontic lesions using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE)

    Institute of Scientific and Technical Information of China (English)

    夏明慧; 亓庆国

    2012-01-01

    目的 利用变性梯度凝胶电泳(DGGE)技术观察牙周牙髓联合病变患牙牙周组织和根管中原始菌群分布状况及其异同,并通过克隆测序技术来试图探讨两部位可能存在的优势菌.方法 从13例牙周牙髓联合病变患牙分别采集患牙根尖1/3处牙周细菌和根管牙髓细菌,提取细菌总DNA,扩增16S rRNA基因可变区,再进行变性梯度凝胶电泳.应用SPSS17.0软件和Quantity One软件对DGGE图谱菌种条带进行统计学分析和聚类分析.对DGGE凝胶中有代表性的条带进行回收和克隆测序.结果 两取菌部位的菌种条带数间有明显的统计学差异(P<0.01),但二者之间无正相关性.二者间的相似系数为13.1% ~62.5%.牙周牙髓联合病变患牙根尖区1/3处牙周菌属可能有弯曲菌属(Campylobacter)、梭杆菌属(Fusobacterium)、奈瑟菌属(Neisseria)等,该处对应根管中菌属可能有优杆菌属(Mogibacterium)、棒状杆菌属(Corynebacterium)、放线菌属(Actinomyces)等.结论 牙周牙髓联合病变(牙周来源)中牙周组织和邻近根管牙髓组织中菌种在数目和结构上有明显不同.该病变牙周组织和根管中可能存在目前尚未被认知的优势菌种.%Objective To compare the bacterial community profiles present in periodontium and root canals of the same tooth diagnosed as combined periodontal-endodontic lesions by using denaturing gradient gel electrophoresis (DGGE).Methods Samples were collected from 13 extracted teeth with advanced periodontitis,endodontic samples from root tip 1/3 root canal,and periodontal samples from the corresponding neighboring periodontium.Genomic DNA was collected for the following universal bacterial primersPCR.The PCR products were then loaded on the DGGE gels to gain separate bands.The typical DGGE bands were excised,PCR-cloned and sequenced.Results The number of bands,which was indicative of the number of bacterial species,was compared intra-group (periodontal and

  20. 静脉用药配置中心参与特殊使用抗菌药物会诊对抗菌药物用量及细菌耐药性的影响%Effect of intravenous drug allocation center participating in the consulta-tion of using special antibacterial drug on the amount of antibacterial drugs and bacterial drug resistance

    Institute of Scientific and Technical Information of China (English)

    何展旺; 杨成密; 杨伟业; 赖飚

    2015-01-01

    Objective To analyze the effect of intravenous drug allocation center participating in the consultation of us-ing special antibacterial drug on the amount of antibacterial drugs and bacterial drug resistance to accumulate experi-ence for promoting rational use of drugs in clinical practice. Methods The average monthly sales amount of the bacte-rial drugs for special use and frequency of drug use (DDDs) were analyzed (from January to June in 2014) before and (from July to December in 2014) after the intravenous drug allocation center participating in the consultation,and at the same time the drug resistance of main pathogenic bacteria against antibacterial drugs for special use was compared by the bacterial drug sensitivity test. Results After the intravenous drug allocation center participating in the consultation, the average monthly sales amount of antibacterial drugs for special use,except imipenem,and frequency of drug use (DDDs) were significantly decreased (P<0.05).Among the bacterial drugs for special use,the amount of Cefepime,Cef-pirome,Vancomycin and Linezolid used decreased obviously.After the intravenous drug allocation center participating in the consultation,the drug resistance rate of the bacterial drugs,except Itraconazole and FushitaYasu,for special use a-gainst Escherichia coli and Pseudomonas aeruginosa,significantly decreased compared with the drug resistance rate of the bacterial drugs be fore the consultation (P<0.05).The drug resistant rate of Meropenem and Imipenem against Bau-manii significantly increased compared with that before the consultation (P<0.05).The drug resistant rate of Meropenem, Imipenem,Linezolid and Teicoplanin against Klebsiella pneumoniae significantly decreased compared with that before the consultation (P<0.05). Conclusion The PIVAS involved in the consultation can ensure the rational use of special use of antimicrobial drugs and delay the bacteria resistance,which provides the guarantee for the scientific and reason

  1. Simultaneous detection of Neisseria meningitidis, Haemophilus influenzae and Streptococcus sp. by polymerase chain reaction for the diagnosis of bacterial meningits Detecção simultânea da Neisseria meningitidis, Haemophilus influenzae e Streptococcus sp. pela reação em cadeia da polimerase no diagnóstico das meningites bacterianas

    Directory of Open Access Journals (Sweden)

    Luciane Failace

    2005-12-01

    Full Text Available The simultaneous detection of Neisseria meningitidis, Haemophilus influenzae, and Streptococcus sp. was assessed by polymerase chain reaction (PCR for the diagnosis of bacterial meningitis, as well as the applicability of PCR as a routine test. A cohort study was carried out with 182 children (2 months to 12 years of age with suspicion of bacterial meningitis. Routine tests identified the etiologic agent in 65/84 children whose clinical status and laboratory findings suggested the presence of bacterial meningitis. Bacterial meningitis was ruled out in 98 children. In 19 children, the etiologic diagnosis was not possible using standard methods; in 14 of these patients, the etiologic agent was identified by PCR (N. meningitidis=12; H. influenzae=1; Streptococcus sp.=1. The sensitivity of PCR was 88.1%; specificity, 99.0%; positive predictive value, 98.7%; and negative predictive, 90.1%. PCR is a useful complementary diagnostic technique, especially when Gram stain, culture, or antigenic detection are negative or inconclusive.Avaliamos o desempenho da reação em cadeia da polimerase (PCR para detecção simultânea da Neisseria meningitidis, Haemophilus influenzae e Streptococcus sp. no diagnóstico das meningites bacterianas e sua aplicabilidade na rotina diagnóstica. Foi realizado um estudo de coorte com 182 crianças apresentando suspeita de meningite bacteriana. Em 84, havia alterações clínicas e laboratoriais sugestivas de meningite bacteriana. Destas, 65 tiveram o agente etiológico identificado pelos métodos laboratoriais de rotina e 19 ficaram sem diagnóstico etiológico. Em 98 pacientes foi excluído o diagnóstico de meningite bacteriana. Analisando o desempenho da PCR encontramos sensibilidade de 88,1%, especificidade de 99,0% e valores preditivos positivo e negativo de 98,7% e 90,1% respectivamente. Nos 19 pacientes com meningite bacteriana mas sem diagnóstico etiológico a PCR detectou microrganismos em 14, sendo 12 N

  2. Vimentin in Bacterial Infections

    Directory of Open Access Journals (Sweden)

    Tim N. Mak

    2016-04-01

    Full Text Available Despite well-studied bacterial strategies to target actin to subvert the host cell cytoskeleton, thus promoting bacterial survival, replication, and dissemination, relatively little is known about the bacterial interaction with other components of the host cell cytoskeleton, including intermediate filaments (IFs. IFs have not only roles in maintaining the structural integrity of the cell, but they are also involved in many cellular processes including cell adhesion, immune signaling, and autophagy, processes that are important in the context of bacterial infections. Here, we summarize the knowledge about the role of IFs in bacterial infections, focusing on the type III IF protein vimentin. Recent studies have revealed the involvement of vimentin in host cell defenses, acting as ligand for several pattern recognition receptors of the innate immune system. Two main aspects of bacteria-vimentin interactions are presented in this review: the role of vimentin in pathogen-binding on the cell surface and subsequent bacterial invasion and the interaction of cytosolic vimentin and intracellular pathogens with regards to innate immune signaling. Mechanistic insight is presented involving distinct bacterial virulence factors that target vimentin to subvert its function in order to change the host cell fate in the course of a bacterial infection.

  3. Analysis of Intestinal Bacterial Flora of Hylan Brown Laying Chicken Fed in Cage by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis%笼养海兰褐蛋雏鸡肠道菌群的聚合酶链式反应-变性梯度凝胶电泳分析

    Institute of Scientific and Technical Information of China (English)

    王秋菊; 崔一喆; 刘胜军; 尹汉周

    2014-01-01

    This study aimed to analyze the intestinal bacterial flora of Hylan brown laying chicken fed in cage by polymerase chain reaction ( PCR)-denaturing gradient gel electrophoresis ( DGGE) .Five 8-week-old chick-ens fed in cage were randomly selected and slaughtered to collect whole intestinal samples.Intestinal contents in duodenum, jejunum, ileum and cecum were individually mixed, and genome DNA of them were extracted, then sequences in hypervariable region of 16S rDNA were amplified with bacterial common primers, finally, the PCR products were used in DGGE analysis.The results showed as follows:there was obvious difference in bacterial flora composition among different intestinal segments.Eight, twelve, eight and nine strains of bacteri-a were isolated from duodenum, jejunum, ileum and cecum, respectively, twenty strains in all, and seven strains of Lactobacillus among those ( including two strains of Lactobacillus aviaries, two strains of Lactococ-cus raffinolactis, one strain of Lactobacillus agilis, one strain of Coprococcus comes and one strain of Lactoba-cillus equigenerosi.There were 3 common strains of bacteria in all intestinal segments, which were one strain of Rummeliibacillus stabekisii, one strain of Lactobacillus equigenerosi and one strain of Gardnerella vaginalis. The results indicate that bacterial flora structure is relative with intestinal segment of Hylan brown laying chick-en fed in cage, and there are differences in intestinal bacterial flora composition among different intestinal seg-ments.%本试验旨在采用聚合酶链式反应( PCR )-变性梯度凝胶电泳( DGGE )法分析笼养海兰褐蛋雏鸡肠道菌群。随机取5只8周龄笼养鸡剖杀,取全部小肠,将5只鸡的十二指肠、空肠、回肠和盲肠内容物分别混匀,提取基因组DNA,以细菌通用引物扩增16S rDNA高变区序列,对PCR产物进行DGGE分析。结果表明:雏鸡不同肠段中细菌菌群组成差别很大,十二指肠、

  4. Evaluation of silicon oil on bacterial growth

    Directory of Open Access Journals (Sweden)

    Fabio Adams

    2012-04-01

    Full Text Available PURPOSE: To analyze the antimicrobial properties of silicon oil (Óleo de Silicone®, Ophthalmos, Brazil on in vitro bacterial growth of different microorganisms related to endophthalmitis. METHODS: The following microorganisms were analyzed: (1 Pseudomonas aeruginosa (ATCC 27583; (2 Escherichia coli (ATCC 25922; (3 Staphylococcus aureus (ATCC 25923; (4 Staphylococcus epidermidis (ATCC 12228; (5 Candida albicans (ATCC 10231; (6 Klebsiella pneumoniae (ATCC 13883; and (7 Streptococcus pneumoniae (ATCC 49619. The plates were incubated at 35 ± 2ºC and its growth examined after 24 hours. An empty disk was placed in the center of each plate as a control. RESULTS: No inhibition halos were verified in any of the plates containing the four different concentrations of the bacterial inocula. CONCLUSIONS: The silicon oil 1000 cps does not have any effect on bacterial growth of any of the studied microrganisms.

  5. Senior Centers

    Medline Plus

    Full Text Available ... Karen Albers] We provide a wide variety of activities -- physical, health, mental health programs with Senior Plus, cognitive ... of games. [Narrator] Many senior centers also offer exercise programs. [Karen Albers] We offer aerobics, tai chi, ...

  6. Senior Centers

    Medline Plus

    Full Text Available ... Living independently at home is something many older adults would like to do as long as they can. Senior centers, adult day care, transportation, and meals programs are long- ...

  7. Senior Centers

    Medline Plus

    Full Text Available ... variety of social and recreational activities. [Karen Albers] We provide a wide variety of activities -- physical, health, ... senior centers also offer exercise programs. [Karen Albers] We offer aerobics, tai chi, tap dancing, ballroom dancing, ...

  8. Senior Centers

    Medline Plus

    Full Text Available ... transportation, and meals programs are long-term care services available in the community which make it easier ... about senior centers and other long-term care services available in your community, contact the Eldercare Locator ...

  9. Senior Centers

    Medline Plus

    Full Text Available ... of games. [Narrator] Many senior centers also offer exercise programs. [Karen Albers] We offer aerobics, tai chi, ... chi, tap dancing, ballroom dancing, square dancing, chair exercise, arthritis classes, yoga, and lots of dancing. [Narrator] ...

  10. Strategy of control for bacterial biofilm processes

    Directory of Open Access Journals (Sweden)

    A. N. Mayansky

    2012-01-01

    Full Text Available Main directions of the modern search of the antibiofilm preparations aimed at adhesive bacterial reactions, control of QS-systems, influence over bis-(3’-5’-cyclic dimeric guanosine monophosphate (cdi-GMP, and secretory bacterial processes are analysed. Approaches for biofilm dispersal and increasing the sensitivity of biofilm bacteria to antimicrobial drugs are discussed. It is underlined that the majority of inhibitor molecules were studied in vitro or in infected mice experiments. It is prognosed that in future there will appear medical preparations which will help for fighting bacterial biofilms preventing their development and spreading in the host organism.

  11. Experimental tests of quantum electrodynamics through the measurement of the reactions e+e- → e+e-, e+e- → γγ, and e+e- → μ+μ- at a center-of-mass energy of 5.2 GeV

    International Nuclear Information System (INIS)

    We report measurements of the reactions e+e- → e+e-, e+e- → γγ, and e+e- → μ+μ- at angles close to 900, relative to Bhabha scattering, at a center-of-mass energy of 5.2 GeV. The results are found to be in agreement with the predictions of quantum electrodynamics

  12. Interfering with bacterial gossip

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Tolker-Nielsen, Tim; Givskov, Michael

    2011-01-01

    defense. Antibiotics exhibit a rather limited effect on biofilms. Furthermore, antibiotics have an ‘inherent obsolescence’ because they select for development of resistance. Bacterial infections with origin in bacterial biofilms have become a serious threat in developed countries. Pseudomonas aeruginosa...... that appropriately target bacteria in their relevant habitat with the aim of mitigating their destructive impact on patients. In this review we describe molecular mechanisms involved in “bacterial gossip” (more scientifically referred to as quorum sensing (QS) and c-di-GMP signaling), virulence, biofilm formation...

  13. Novel Nitrocellulose Made from Bacterial Cellulose

    Science.gov (United States)

    Sun, Dong-Ping; Ma, Bo; Zhu, Chun-Lin; Liu, Chang-Sheng; Yang, Jia-Zhi

    2010-04-01

    Nitrocellulose (NC) is useful in several industrial segments, especially in the production of gun, rocket, and missile propellants. The conventional way to prepare NC is done through the nitration of plant cellulose with nitric acid. In this work, bacterial cellulose nitrate (NBC) is synthesized by bacterial cellulose (BC) and nitro-sulfric acid under heterogeneous conditions. NBC with the degree of substitution (DS) of 1-2.85 was obtained, and the effects of sulfuric to nitric ratio, reaction temperature, and reaction time on the value of DS of NBC are discussed. The samples are also characterized by elemental analysis, thermal analysis, Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction.

  14. 蔗糖凝胶治疗细菌性阴道病的多中心、随机、双盲、平行对照Ⅲ期临床试验%Sucrose gel for treatment of bacterial vaginosis:a randomized, double-blind, multi-center, parallel-group, phase Ⅲ clinical trial

    Institute of Scientific and Technical Information of China (English)

    肖冰冰; 张岱; 陈锐; 史惠蓉; 辛晓燕; 王惠兰; 庞义存; 朱赛楠; 姚晨

    2015-01-01

    目的:通过多中心、随机、双盲、平行对照的临床研究,进一步评价蔗糖凝胶治疗细菌性阴道病的有效性及安全性. 方法:选择5个研究中心的533例细菌性阴道病患者作为研究对象,依据随机表按对照组与试验组为2:3比例随机入组,甲硝唑凝胶5. 0 g组(对照组)214例,蔗糖凝胶5. 0 g组(实验组)319例,两组均采取每日早晚各一次阴道上药,连用5 d的疗程进行治疗. 分别于治疗第7~10天、第21~30天进行疗效观察及安全性评价.结果:治疗第7~10天,甲硝唑凝胶组和蔗糖凝胶组的临床综合疗效治愈率分别为70. 53%和80. 83%,阴道分泌物涂片Nugent积分痊愈率分别为71. 50%和81. 15%,差异均有统计学意义(P0. 05). 结论:蔗糖凝胶治疗细菌性阴道病的临床综合疗效近期(治疗第7~10天)及恢复阴道菌群方面明显优于甲硝唑凝胶,远期治愈率(治疗第21~30天)与甲硝唑凝胶相当,可成为治疗细菌性阴道病的新策略.%Objective:To evaluate the cure effectiveness and safety of sucrose gel in the treatment of bacterial vaginosis through a multi-center, randomized, double-blind, parallel controlled clinical study. Methods:A clinical research method of multi-center, randomly double-blind, and dose group parallel comparison was adopted. In the study, 533 patients with bacterial vaginosis were randomly divided into two groups, which included 214 cases in the control group (5. 0 g metronidazole gel) and 319 cases in the trial group (5. 0 g sucrose gel ). The patients were treated with different medication according to the group where they were. All the cases in these two groups were treated with drugs vaginally twice in a day, morning and evening separately, for 5 days. The curative effect and safety evaluation were assessed from 7 to 10 days and 21 to 30 days after treatment respectively. Results: The efficacy of the comprehensive clinical treatment showed that the cure rate of metronidazole gel group

  15. Bacterial Wound Culture

    Science.gov (United States)

    ... Home Visit Global Sites Search Help? Bacterial Wound Culture Share this page: Was this page helpful? Also known as: Aerobic Wound Culture; Anaerobic Wound Culture Formal name: Culture, wound Related ...

  16. Bacterial surface adaptation

    Science.gov (United States)

    Utada, Andrew

    2014-03-01

    Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

  17. Bacterial intermediate filaments

    DEFF Research Database (Denmark)

    Charbon, Godefroid; Cabeen, M.; Jacobs-Wagner, C.

    2009-01-01

    Crescentin, which is the founding member of a rapidly growing family of bacterial cytoskeletal proteins, was previously proposed to resemble eukaryotic intermediate filament (IF) proteins based on structural prediction and in vitro polymerization properties. Here, we demonstrate that crescentin...

  18. Bacterial Meningitis in Infants

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-04-01

    Full Text Available A retrospective study of 80 infantile patients (ages 30-365 days; 47 male, 33 female with culture-proven bacterial meningitis seen over a 16 year period (1986-2001 is reported from Taiwan.

  19. Senior Centers

    Medline Plus

    Full Text Available ... dancing. [Narrator] These centers can provide entree to new activities and expand a person’s social contacts. [Karen ... meeting all their interests and introducing them to new things; whether it’s an arts and crafts project, ...

  20. The bacterial lipocalins.

    Science.gov (United States)

    Bishop, R E

    2000-10-18

    The lipocalins were once regarded as a eukaryotic protein family, but new members have been recently discovered in bacteria. The first bacterial lipocalin (Blc) was identified in Escherichia coli as an outer membrane lipoprotein expressed under conditions of environmental stress. Blc is distinguished from most lipocalins by the absence of intramolecular disulfide bonds, but the presence of a membrane anchor is shared with two of its closest homologues, apolipoprotein D and lazarillo. Several common features of the membrane-anchored lipocalins suggest that each may play an important role in membrane biogenesis and repair. Additionally, Blc proteins are implicated in the dissemination of antibiotic resistance genes and in the activation of immunity. Recent genome sequencing efforts reveal the existence of at least 20 bacterial lipocalins. The lipocalins appear to have originated in Gram-negative bacteria and were probably transferred horizontally to eukaryotes from the endosymbiotic alpha-proteobacterial ancestor of the mitochondrion. The genome sequences also reveal that some bacterial lipocalins exhibit disulfide bonds and alternative modes of subcellular localization, which include targeting to the periplasmic space, the cytoplasmic membrane, and the cytosol. The relationships between bacterial lipocalin structure and function further illuminate the common biochemistry of bacterial and eukaryotic cells.

  1. IRASM Center

    International Nuclear Information System (INIS)

    IRASM is a national center for radiation processing developed around an industrial Co60 gamma irradiator. Being a department in an R and D national institute, IRASM Center is dealing with radiation treatment, pre/post microbiological control, validation of irradiation sterilization, detection of irradiated foodstuffs. Training is available for operators of new irradiation facilities focused on radiation technologies, dosimetry, sterilization, food treatment, conservation by irradiation of cultural heritage, quality assurance. Expertise on proper choosing the plastics for packaging versus dose is offered to the potential clients. IRASM Center is also involved in interdisciplinary applied research like chitosan treatment, sterile male technique or implementation of irradiation step in production of pharmaceuticals. All important activities: irradiation treatment, dosimetry, microbiology, detection of irradiated food, radioprotection, nuclear safety, physical protection. are performed in accordance with the proper standards in the frame of a certified quality management system. In this way Co60 industrial sources, a byproduct of certain nuclear power plants like Candu type, appear to be the key of a large technical and R and D domain. (authors)

  2. Diagnosis of bacterial vaginosis

    Directory of Open Access Journals (Sweden)

    Đukić Slobodanka

    2013-01-01

    Full Text Available Bacterial vaginosis is a common, complex clinical syndrome characterized by alterations in the normal vaginal flora. When symptomatic, it is associated with a malodorous vaginal discharge and on occasion vaginal burning or itching. Under normal conditions, lactobacilli constitute 95% of the bacteria in the vagina. Bacterial vaginosis is associated with severe reduction or absence of the normal H2O2­producing lactobacilli and overgrowth of anaerobic bacteria and Gardnerella vaginalis, Atopobium vaginae, Mycoplasma hominis and Mobiluncus species. Most types of infectious disease are diagnosed by culture, by isolating an antigen or RNA/DNA from the microbe, or by serodiagnosis to determine the presence of antibodies to the microbe. Therefore, demonstration of the presence of an infectious agent is often a necessary criterion for the diagnosis of the disease. This is not the case for bacterial vaginosis, since the ultimate cause of the disease is not yet known. There are a variety of methods for the diagnosis of bacterial vaginosis but no method can at present be regarded as the best. Diagnosing bacterial vaginosis has long been based on the clinical criteria of Amsel, whereby three of four defined criteria must be satisfied. Nugent’s scoring system has been further developed and includes validation of the categories of observable bacteria structures. Up­to­date molecular tests are introduced, and better understanding of vaginal microbiome, a clear definition for bacterial vaginosis, and short­term and long­term fluctuations in vaginal microflora will help to better define molecular tests within the broader clinical context.

  3. Safety analysis of 2% fusidic acid cream in multi-center treatment of bacterial skin disease%2%夫西地酸乳膏多中心治疗细菌性皮肤病安全性分析

    Institute of Scientific and Technical Information of China (English)

    于云和

    2014-01-01

    Objective To investigate the clinical efficacy and safety of 2% fusidic acid cream in the treatment of bacterial skin disease.Methods Randomly selected 146 patients who were diagnosed as bacterial skin diseases in Xinye county people' s hospital from May 2010 to July 2013,they were randomly divided into experimental group and control group.In accordance with the principles of multi-center open experiment,the experimental group was taken 2 % fusidic acid cream,the control group was taken 2% mupirocin ointment.And the treatment results of the two groups were analyzed.Results The total efficiency of the experimental group (95.9%) was significantly higher than that of control group (78.1%),the difference was significant(P <0.05).Adverse symptoms did not occur during the treatment in the experimental group,there were four patients had local burning and itching during treatment in control group,and the symptoms disappeared later.Conclusions Using 2% fusidic acid cream in treating bacterial skin diseases has significant effect,it is safe and reliable,and it is recommended to be further promote in clinical practice.%目的 探讨采用2%夫西地酸乳膏治疗细菌性皮肤病的临床疗效和安全性.方法 随机选取2010年5月至2013年7月新野县人民医院收治的确诊为细菌性皮肤病患者146例,随机平均分为实验组和对照组,按照多中心开放性实验原则,实验组采用2%夫西地酸乳膏治疗,对照组采用2%莫匹罗星软膏治疗,对治疗结果进行分析.结果 本研究实验组治疗总有效率(95.9%)明显高于对照组(78.1%),差异有统计学意义(P<0.05);实验组治疗期间未发生不良症状,对照组4例出现局部灼热和瘙瘁感,一段时间后症状自行消失.结论 采用2%夫西地酸乳膏对细菌性皮肤病患者进行治疗,疗效显著,安全可靠,建议在临床上进一步推广.

  4. Bacterial glycosyltransferase toxins.

    Science.gov (United States)

    Jank, Thomas; Belyi, Yury; Aktories, Klaus

    2015-12-01

    Mono-glycosylation of host proteins is a common mechanism by which bacterial protein toxins manipulate cellular functions of eukaryotic target host cells. Prototypic for this group of glycosyltransferase toxins are Clostridium difficile toxins A and B, which modify guanine nucleotide-binding proteins of the Rho family. However, toxin-induced glycosylation is not restricted to the Clostridia. Various types of bacterial pathogens including Escherichia coli, Yersinia, Photorhabdus and Legionella species produce glycosyltransferase toxins. Recent studies discovered novel unexpected variations in host protein targets and amino acid acceptors of toxin-catalysed glycosylation. These findings open new perspectives in toxin as well as in carbohydrate research.

  5. Bacterial community reconstruction using compressed sensing.

    Science.gov (United States)

    Amir, Amnon; Zuk, Or

    2011-11-01

    Bacteria are the unseen majority on our planet, with millions of species and comprising most of the living protoplasm. We propose a novel approach for reconstruction of the composition of an unknown mixture of bacteria using a single Sanger-sequencing reaction of the mixture. Our method is based on compressive sensing theory, which deals with reconstruction of a sparse signal using a small number of measurements. Utilizing the fact that in many cases each bacterial community is comprised of a small subset of all known bacterial species, we show the feasibility of this approach for determining the composition of a bacterial mixture. Using simulations, we show that sequencing a few hundred base-pairs of the 16S rRNA gene sequence may provide enough information for reconstruction of mixtures containing tens of species, out of tens of thousands, even in the presence of realistic measurement noise. Finally, we show initial promising results when applying our method for the reconstruction of a toy experimental mixture with five species. Our approach may have a potential for a simple and efficient way for identifying bacterial species compositions in biological samples. All supplementary data and the MATLAB code are available at www.broadinstitute.org/?orzuk/publications/BCS/.

  6. Bacterial Acclimation Inside an Aqueous Battery.

    Directory of Open Access Journals (Sweden)

    Dexian Dong

    Full Text Available Specific environmental stresses may lead to induced genomic instability in bacteria, generating beneficial mutants and potentially accelerating the breeding of industrial microorganisms. The environmental stresses inside the aqueous battery may be derived from such conditions as ion shuttle, pH gradient, free radical reaction and electric field. In most industrial and medical applications, electric fields and direct currents are used to kill bacteria and yeast. However, the present study focused on increasing bacterial survival inside an operating battery. Using a bacterial acclimation strategy, both Escherichia coli and Bacillus subtilis were acclimated for 10 battery operation cycles and survived in the battery for over 3 days. The acclimated bacteria changed in cell shape, growth rate and colony color. Further analysis indicated that electrolyte concentration could be one of the major factors determining bacterial survival inside an aqueous battery. The acclimation process significantly improved the viability of both bacteria E. coli and B. subtilis. The viability of acclimated strains was not affected under battery cycle conditions of 0.18-0.80 mA cm(-2 and 1.4-2.1 V. Bacterial addition within 1.0×10(10 cells mL(-1 did not significantly affect battery performance. Because the environmental stress inside the aqueous battery is specific, the use of this battery acclimation strategy may be of great potential for the breeding of industrial microorganisms.

  7. Bacterial extracellular lignin peroxidase

    Science.gov (United States)

    Crawford, Donald L.; Ramachandra, Muralidhara

    1993-01-01

    A newly discovered lignin peroxidase enzyme is provided. The enzyme is obtained from a bacterial source and is capable of degrading the lignin portion of lignocellulose in the presence of hydrogen peroxide. The enzyme is extracellular, oxidative, inducible by lignin, larch wood xylan, or related substrates and capable of attacking certain lignin substructure chemical bonds that are not degradable by fungal lignin peroxidases.

  8. Bacterial Skin Infections

    Science.gov (United States)

    ... or scraped, the injury should be washed with soap and water and covered with a sterile bandage. Petrolatum may be applied to open areas to keep the tissue moist and to try to prevent bacterial invasion. Doctors recommend that people do not use ...

  9. Vimentin in Bacterial Infections

    DEFF Research Database (Denmark)

    Mak, Tim N; Brüggemann, Holger

    2016-01-01

    filaments (IFs). IFs have not only roles in maintaining the structural integrity of the cell, but they are also involved in many cellular processes including cell adhesion, immune signaling, and autophagy, processes that are important in the context of bacterial infections. Here, we summarize the knowledge...

  10. Bacterial microflora of nectarines

    Science.gov (United States)

    Microflora of fruit surfaces has been the best source of antagonists against fungi causing postharvest decays of fruit. However, there is little information on microflora colonizing surfaces of fruits other than grapes, apples, and citrus fruit. We characterized bacterial microflora on nectarine f...

  11. Modeling intraocular bacterial infections.

    Science.gov (United States)

    Astley, Roger A; Coburn, Phillip S; Parkunan, Salai Madhumathi; Callegan, Michelle C

    2016-09-01

    Bacterial endophthalmitis is an infection and inflammation of the posterior segment of the eye which can result in significant loss of visual acuity. Even with prompt antibiotic, anti-inflammatory and surgical intervention, vision and even the eye itself may be lost. For the past century, experimental animal models have been used to examine various aspects of the pathogenesis and pathophysiology of bacterial endophthalmitis, to further the development of anti-inflammatory treatment strategies, and to evaluate the pharmacokinetics and efficacies of antibiotics. Experimental models allow independent control of many parameters of infection and facilitate systematic examination of infection outcomes. While no single animal model perfectly reproduces the human pathology of bacterial endophthalmitis, investigators have successfully used these models to understand the infectious process and the host response, and have provided new information regarding therapeutic options for the treatment of bacterial endophthalmitis. This review highlights experimental animal models of endophthalmitis and correlates this information with the clinical setting. The goal is to identify knowledge gaps that may be addressed in future experimental and clinical studies focused on improvements in the therapeutic preservation of vision during and after this disease. PMID:27154427

  12. Piezonuclear Reactions

    CERN Document Server

    Cardone, Fabio; Petrucci, Andrea

    2010-01-01

    In this paper, we deal with the subject of piezonuclear reactions, namely nuclear reactions (of new type) triggered by pressure waves. We discuss the experimental evidences obtained in the last two decades, which can be summarized essentially as follows: experiments in cavitation of liquids, where transmutation of elements, creation of elements and emission of neutrons have been observed; emission of neutrons in brittle failure of solids subjected to mechanical pressure; alteration of the lifetime of un unstable element (thorium) subjected to cavitation. A theoretical model to explain these facts is proposed. Future perspectives of these experimental and theoretical investigations are also underlined.

  13. Future of Bacterial Therapy of Cancer.

    Science.gov (United States)

    Hoffman, Robert M

    2016-01-01

    Bacterial therapy of cancer has a centuries-long history and was first-line therapy at the hospital in New York City that would become Memorial Sloan-Kettering Cancer Center, under Dr. William B. Coley. However, after Coley's death in 1936, bacterial therapy of cancer ceased in the clinic until the present century. Clinical trials have been recently carried out for strains of the obligate anaerobe Clostridium novyi with the toxin gene deleted, and on an attenuated strain of Salmonella typhimurium (S. typhimurium), which is a facultative anaerobe that can grow in viable, as well as necrotic, areas of tumors, unlike Clostridium, which can only grow in the hypoxic areas. Our laboratory has developed the novel strain S. typhimurium A1-R that is effective against all tumor types in clinically-relevant mouse models, including patient-derived orthotopic xenograft (PDOX) mouse models. This chapter suggests future clinical applications for S. typhimurium A1-R.

  14. Detection of Vibrio Cholerae in Turtles by Real Time Polymerase Chain Reaction, Colloidal Gold Immunochromatographic Assay and Conventional Bacterial Culture%实时荧光PCR法、胶体金法和培养法检测甲鱼中霍乱弧菌

    Institute of Scientific and Technical Information of China (English)

    颜淑妩; 李哲婷; 邓婵

    2012-01-01

    目的 优化水产品甲鱼中霍乱弧菌的检测程序,提高甲鱼中霍乱弧菌检出率.方法 用实时荧光PCR、常规细菌培养、胶体金法同时对甲鱼中霍乱弧菌进行检测,并用实时荧光PCR法检测标本中霍乱弧菌ctx基因.结果 共检测185份甲鱼样品,其中实时荧光PCR法检出28份霍乱弧菌核酸阳性,阳性率为15.14%;6份ctx基因核酸阳性,阳性率21.43% (6/28).常规细菌培养法分离出2株菌株,一株为O139群霍乱弧菌,一株为小川型霍乱弧菌,用实时荧光PCR检测这两株纯培养菌株或原始标本,霍乱弧菌ctx基因均为阴性;胶体金法未检出阳性标本.结论 对于水产品标本,可先用实时荧光PCR法筛检霍乱弧菌,阳性标本再进行传统细菌分离培养,以提高霍乱弧菌菌株的检出率;同时阳性标本进行霍乱弧菌ctx基因核酸检测,如也为阳性,需提高警惕,加强流行病学上的预防控制措施,及时防范霍乱疫情的发生.%Objective To optimize the detection procedure of Vibrio Cholerae (v. cholerae) and increase its detection rate in turtles. Methods The v. cholerae in turtles was detected by real time polymerase chain reaction (real time PCR), conventional bacterial culture and colloidal gold immunochrornatographic assay, and the ctx gene of the virus was detected by real time PCR. Results Real time PCR revealed that among 185 turtle samples, 28 ones were positive with v. cholerae nucleic acid, with a positive rate of 15.14% (28/185), and six samples were positive with ctx gene, with a positive rate of 21.43% (6/ 28). Two strains of v.cholerae were isolated by conventional bacterial culture, Vibrio cholerae O139, and Vibrio cholerae Ol serotype Ogawa. Neither the pure cultures nor the original samples of both stains were positive with ctx gene. No v. cholerae was detected by colloidal gold immunochromatugraphic assay. Conclusions For V. cholerae detection in seafood samples, real time PCR can be first used for

  15. Heme uptake in bacterial pathogens

    OpenAIRE

    Contreras, Heidi; Chim, Nicholas; Credali, Alfredo; Goulding, Celia W.

    2014-01-01

    Iron is an essential nutrient for the survival of organisms. Bacterial pathogens possess specialized pathways to acquire heme from their human hosts. In this review, we present recent structural and biochemical data that provide mechanistic insights into several bacterial heme uptake pathways, encompassing the sequestration of heme from human hemoproteins to secreted or membrane-associated bacterial proteins, the transport of heme across bacterial membranes, and the degradation of heme within...

  16. 培养与聚合酶链反应联合进行住院患儿肺炎细菌病原学检测%Bacterial etiology of pneumonia in hospitalized children:combined detection with culture and polymerase chain reaction

    Institute of Scientific and Technical Information of China (English)

    郑跃杰; 邓继岿; 赵瑞珍

    2008-01-01

    目的 探讨细菌培养与病原特异性DNA联合检测住院患儿肺炎细菌病原的应用价值.方法对187例肺炎患儿的深部呼吸道吸引物进行肺炎链球菌、流感嗜血杆菌选择性培养和普通培养,并且对同一标本采用靶序列富集多重PCR(Tem-PCB)扩增结合Luminex液态芯片检测平台进行定量测定,检测肺炎链球菌、流感嗜血杆菌、金黄色葡萄球菌、肺炎克雷伯杆菌、大肠杆菌、嗜肺军团菌、绿脓杆菌、鲍曼不动杆菌等14种病原菌的特异性DNA.结果细菌培养的总检出率为40.1%(75/187,含3例检出2种病原菌),病原菌依次为流感嗜血杆菌17.1%、大肠杆菌8.6%、肺炎克雷伯杆菌6.4%、金黄色葡萄球菌4.8%、肺炎链球菌3.7%、绿脓杆菌1.6%、鲍曼不动杆菌1.1%和阴沟肠杆菌1.1%.以细菌培养或Tem-PCR任一阳性为标准,联合检测的总检出率为78.6%(147/187),病原菌依次为流感嗜血杆菌28.9%、肺炎链球菌19.3%、大肠杆菌8.6%、肺炎克雷伯杆菌6.4%、金黄色葡萄球菌5.9%、鲍曼不动杆菌5.9%、绿脓杆菌2.7%和阴沟肠杆菌1.1%.结论 Tem-PCR能提高流感嗜血杆菌、肺炎链球菌、金黄色葡萄球菌、绿脓杆菌和鲍曼不动杆菌的检出例数.细菌培养与病原特异性DNA联合检测应用能显著提高肺炎病原的检出率,可能更真实地反映肺炎的细菌病原学情况.%Objective Bacterial cultures from respiratory aspirate or sputum have been the conventional diagnostic method for neumonia,but the results of culture was often affected by early extensive rise of antibiotics,sample collection and delivery.The objective of this stuay was to explore application of the combined detection of culture and polymerase chain reaction (PCR) assay in hospitalized children with pneumonia.Methods Totally 187 hospitalized children with pneumonia were enrolled.The age of the patients ranged from 1 month to 10 years,124 were male,63 female;175 of the patients receired

  17. Multinucleon transfer reactions

    International Nuclear Information System (INIS)

    Nuclear reactions induced by complex nuclei are studied. The description of the single neutron transfer is used to show some aspect of the theoretical treatment of transfer reactions and rules concerning the dependence of cross sections on quantum numbers of the initial and final channels are deduced. Strongly excited states of 20Ne, 19F, sup(16,17)0, 15N were studied experimentally by using different projectile-target combinations in the four-particle, eight-particle and ten-particle transfer reactions, leading to the some final nuclei. Obtained results are discussed. In addition, studies of the projectile break-up phenomenon were performed. The dissociation of 6Li and 7Li projectiles was investigated in reactions on Pb, Sn and Ni nuclei. These nuclei were chosen to allow measurements at one incident energy below, above and at the Coulomb barrier. The observed spectra indicate that the process proceeds primarily via the resonance level but the shape deviates from the shape which was calculated assuming isotropic decay of the excited 6Li in its center of mass system. The investigations of the elastic scattering turned out to be more fruitful and allowed to define better the Coulomb barrier for the 6Li-target system. (S.B.)

  18. Bacterial chemoreceptors and chemoeffectors.

    Science.gov (United States)

    Bi, Shuangyu; Lai, Luhua

    2015-02-01

    Bacteria use chemotaxis signaling pathways to sense environmental changes. Escherichia coli chemotaxis system represents an ideal model that illustrates fundamental principles of biological signaling processes. Chemoreceptors are crucial signaling proteins that mediate taxis toward a wide range of chemoeffectors. Recently, in deep study of the biochemical and structural features of chemoreceptors, the organization of higher-order clusters in native cells, and the signal transduction mechanisms related to the on-off signal output provides us with general insights to understand how chemotaxis performs high sensitivity, precise adaptation, signal amplification, and wide dynamic range. Along with the increasing knowledge, bacterial chemoreceptors can be engineered to sense novel chemoeffectors, which has extensive applications in therapeutics and industry. Here we mainly review recent advances in the E. coli chemotaxis system involving structure and organization of chemoreceptors, discovery, design, and characterization of chemoeffectors, and signal recognition and transduction mechanisms. Possible strategies for changing the specificity of bacterial chemoreceptors to sense novel chemoeffectors are also discussed.

  19. Bacterial Colony Optimization

    Directory of Open Access Journals (Sweden)

    Ben Niu

    2012-01-01

    Full Text Available This paper investigates the behaviors at different developmental stages in Escherichia coli (E. coli lifecycle and developing a new biologically inspired optimization algorithm named bacterial colony optimization (BCO. BCO is based on a lifecycle model that simulates some typical behaviors of E. coli bacteria during their whole lifecycle, including chemotaxis, communication, elimination, reproduction, and migration. A newly created chemotaxis strategy combined with communication mechanism is developed to simplify the bacterial optimization, which is spread over the whole optimization process. However, the other behaviors such as elimination, reproduction, and migration are implemented only when the given conditions are satisfied. Two types of interactive communication schemas: individuals exchange schema and group exchange schema are designed to improve the optimization efficiency. In the simulation studies, a set of 12 benchmark functions belonging to three classes (unimodal, multimodal, and rotated problems are performed, and the performances of the proposed algorithms are compared with five recent evolutionary algorithms to demonstrate the superiority of BCO.

  20. [Bacterial diseases of rape].

    Science.gov (United States)

    Zakharova, O M; Mel'nychuk, M D; Dankevych, L A; Patyka, V P

    2012-01-01

    Bacterial destruction of the culture was described and its agents identified in the spring and winter rape crops. Typical symptoms are the following: browning of stem tissue and its mucilagization, chlorosis of leaves, yellowing and beginning of soft rot in the place of leaf stalks affixion to stems, loss of pigmentation (violet). Pathogenic properties of the collection strains and morphological, cultural, physiological, and biochemical properties of the agents of rape's bacterial diseases isolated by the authors have been investigated. It was found that all the isolates selected by the authors are highly or moderately aggressive towards different varieties of rape. According to the complex of phenotypic properties 44% of the total number of isolates selected by the authors are related to representatives of the genus Pseudomonas, 37% - to Xanthomonas and 19% - to Pectobacterium. PMID:23293826

  1. Bacterial transformation of terpenoids

    International Nuclear Information System (INIS)

    Data on the bacterial transformation of terpenoids published in the literature in the past decade are analyzed. Possible pathways for chemo-, regio- and stereoselective modifications of terpenoids are discussed. Considerable attention is given to new technological approaches to the synthesis of terpenoid derivatives suitable for the use in the perfume and food industry and promising as drugs and chiral intermediates for fine organic synthesis. The bibliography includes 246 references

  2. Supramolecular bacterial systems

    OpenAIRE

    Sankaran, Shrikrishnan

    2015-01-01

    For nearly over a decade, a wide variety of dynamic and responsive supramolecular architectures have been investigated and developed to address biological systems. Since the non-covalent interactions between individual molecular components in such architectures are similar to the interactions found in living systems, it was possible to integrate chemically-synthesized and naturally-occurring components to create platforms with interesting bioactive properties. Bacterial cells and recombinant ...

  3. Bacterial Colony Optimization

    OpenAIRE

    Ben Niu; Hong Wang

    2012-01-01

    This paper investigates the behaviors at different developmental stages in Escherichia coli (E. coli) lifecycle and developing a new biologically inspired optimization algorithm named bacterial colony optimization (BCO). BCO is based on a lifecycle model that simulates some typical behaviors of E. coli bacteria during their whole lifecycle, including chemotaxis, communication, elimination, reproduction, and migration. A newly created chemotaxis strategy combined with communication mechanism i...

  4. Cerebrospinal fluid ferritin in children with viral and bacterial meningitis.

    Science.gov (United States)

    Rezaei, M; Mamishi, S; Mahmoudi, S; Pourakbari, B; Khotaei, G; Daneshjou, K; Hashemi, N

    2013-01-01

    Despite the fact that the prognosis of bacterial meningitis has been improved by the influence of antibiotics, this disease is still one of the significant causes of morbidity and mortality in children. Rapid differentiation between bacterial and aseptic meningitis, and the need for immediate antibiotic treatment in the former, is crucial in the prognosis of these patients. Ferritin is one of the most sensitive biochemical markers investigated in cerebrospinal fluid (CSF) for the early diagnosis of bacterial meningitis. The present study aims to evaluate the diagnostic capability of CSF ferritin in differentiating bacterial and viral meningitis in the paediatric setting. A cross-sectional study was carried out in the referral Children's Medical Center Hospital, Tehran, during 2008 and 2009. According to the inclusion criteria, CSF samples from 42 patients with suspected meningitis were obtained and divided into two meningitis groups, bacterial (n = 18) and viral (n = 24). Ferritin and other routine determinants (i.e., leucocytes, protein and glucose) were compared between the two groups. Ferritin concentration in the bacterial meningitis group was 106.39 +/- 86.96 ng/dL, which was considerably higher than in the viral meningitis group (10.17 +/- 14.09, P meningitis group and showed a positive correlation with CSF ferritin. In conclusion, this study suggests that CSF ferritin concentration is an accurate test for the early differentiation of bacterial and aseptic meningitis; however, further investigation on a larger cohort of patients is required to confirm this finding.

  5. Identification of Bacterial Small RNAs by RNA Sequencing

    DEFF Research Database (Denmark)

    Gómez Lozano, María; Marvig, Rasmus Lykke; Molin, Søren;

    2014-01-01

    Small regulatory RNAs (sRNAs) in bacteria are known to modulate gene expression and control a variety of processes including metabolic reactions, stress responses, and pathogenesis in response to environmental signals. A method to identify bacterial sRNAs on a genome-wide scale based on RNA...

  6. Coupling oxygen consumption with hydrocarbon oxidation in bacterial multicomponent monooxygenases

    OpenAIRE

    Wang, Weixue; Liang, Alexandria D.; Lippard, Stephen J.

    2015-01-01

    A fundamental goal in catalysis is the coupling of multiple reactions to yield a desired product. Enzymes have evolved elegant approaches to address this grand challenge. A salient example is the biological conversion of methane to methanol catalyzed by soluble methane monooxygenase (sMMO), a member of the bacterial multicomponent monooxygenase (BMM) superfamily.

  7. Kinematical coincidence method in transfer reactions

    Energy Technology Data Exchange (ETDEWEB)

    Acosta, L.; Amorini, F. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Auditore, L. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Berceanu, I. [Institute for Physics and Nuclear Engineering, Bucharest (Romania); Cardella, G., E-mail: cardella@ct.infn.it [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Chatterjiee, M.B. [Saha Institute for Nuclear Physics, Kolkata (India); De Filippo, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Francalanza, L.; Gianì, R. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); Grassi, L. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Rudjer Boskovic Institute, Zagreb (Croatia); Grzeszczuk, A. [Institut of Physics, University of Silesia, Katowice (Poland); La Guidara, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lanzalone, G. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Facoltà di Ingegneria e Architettura, Università Kore, Enna (Italy); Lombardo, I. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Scienze Fisiche, Università Federico II and INFN Sezione di Napoli (Italy); Loria, D.; Minniti, T. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Pagano, E.V. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); and others

    2013-07-01

    A new method to extract high resolution angular distributions from kinematical coincidence measurements in binary reactions is presented. Kinematics is used to extract the center of mass angular distribution from the measured energy spectrum of light particles. Results obtained in the case of {sup 10}Be+p→{sup 9}Be+d reaction measured with the CHIMERA detector are shown. An angular resolution of few degrees in the center of mass is obtained. The range of applicability of the method is discussed.

  8. Kinematical coincidence method in transfer reactions

    CERN Document Server

    Acosta, L; Auditore, L; Berceanu, I; Cardella, G; Chatterjiee, M B; De Filippo, E; FrancalanzA, L; Gianì, R; Grassi, L; Grzeszczuk, A; La Guidara, E; Lanzalone, G; Lombardo, I; Loria, D; Minniti, T; Pagano, E V; Papa, M; Pirrone, S; Politi, G; Pop, A; Porto, F; Rizzo, F; Rosato, E; Russotto, P; Santoro, S; Trifirò, A; Trimarchi, M; Verde, G; Vigilante, M

    2012-01-01

    A new method to extract high resolution angular distributions from kinematical coincidence measurements in binary reactions is presented. Kinematic is used to extract the center of mass angular distribution from the measured energy spectrum of light particles. Results obtained in the case of 10Be+p-->9Be+d reaction measured with the CHIMERA detector are shown. An angular resolution of few degrees in the center of mass is obtained.

  9. Coupling Oxygen Consumption with Hydrocarbon Oxidation in Bacterial Multicomponent Monooxygenases.

    Science.gov (United States)

    Wang, Weixue; Liang, Alexandria D; Lippard, Stephen J

    2015-09-15

    A fundamental goal in catalysis is the coupling of multiple reactions to yield a desired product. Enzymes have evolved elegant approaches to address this grand challenge. A salient example is the biological conversion of methane to methanol catalyzed by soluble methane monooxygenase (sMMO), a member of the bacterial multicomponent monooxygenase (BMM) superfamily. sMMO is a dynamic protein complex of three components: a hydroxylase, a reductase, and a regulatory protein. The active site, a carboxylate-rich non-heme diiron center, is buried inside the 251 kDa hydroxylase component. The enzyme processes four substrates: O2, protons, electrons, and methane. To couple O2 activation to methane oxidation, timely control of substrate access to the active site is critical. Recent studies of sMMO, as well as its homologues in the BMM superfamily, have begun to unravel the mechanism. The emerging and unifying picture reveals that each substrate gains access to the active site along a specific pathway through the hydroxylase. Electrons and protons are delivered via a three-amino-acid pore located adjacent to the diiron center; O2 migrates via a series of hydrophobic cavities; and hydrocarbon substrates reach the active site through a channel or linked set of cavities. The gating of these pathways mediates entry of each substrate to the diiron active site in a timed sequence and is coordinated by dynamic interactions with the other component proteins. The result is coupling of dioxygen consumption with hydrocarbon oxidation, avoiding unproductive oxidation of the reductant rather than the desired hydrocarbon. To initiate catalysis, the reductase delivers two electrons to the diiron(III) center by binding over the pore of the hydroxylase. The regulatory component then displaces the reductase, docking onto the same surface of the hydroxylase. Formation of the hydroxylase-regulatory component complex (i) induces conformational changes of pore residues that may bring protons to the

  10. Reação de genótipos de feijão ao crestamento bacteriano comum, avaliado por dois métodos de inoculação Reaction of bean genotypes to the common bacterial blight, evaluated by two inoculation methods

    Directory of Open Access Journals (Sweden)

    Alciani da Silva

    2009-01-01

    Full Text Available Conhecer a resistência de genótipos de feijão à fitopatógenos é importante para uso em programas de melhoramento genético. Duas técnicas de inoculação bacteriana foram testadas para avaliar a sensibilidade de genótipos de feijão ao crestamento bacteriano comum, causado por Xanthomonas axonopodis pv. phaseoli. Foram inoculados folíolos de 56 genótipos de feijão, utilizando-se das técnicas de agulhas múltiplas e incisão com tesoura, utilizando o isolado XAP 15497. Foi possível classificar 21 genótipos resistentes, 13 moderadamente resistentes, 9 moderadamente suscetíveis e 13 suscetíveis pelo método de inoculação com agulhas múltiplas. No método de inoculação com tesoura, foi possível classificar 24 genótipos como resistentes, 21 como moderadamente resistentes, 7 como moderadamente suscetíveis e 4 suscetíveis. Os genótipos IPR Chopim, IAPAR 81, IAPAR 16, BRS Campeiro, BRS Radiante, IAPAR 80, UTF 6, SM 9906, PI 2072620, LP 01-51, PB 4, Uirapuru, IAPAR 20, Zonin, IAPAR 31, 2 V, CNPF 7762, BRS Talismã, Pérola, Lon Rosinha e UTF 9 tiveram comportamento semelhante diante dos dois métodos de inoculação. Verificou-se que os dois métodos de inoculação foram eficientes para a determinação das reações de suscetibilidade e resistência dos genótipos. Porém, a técnica de inoculação com agulhas múltiplas demonstrou maior praticidade e precisão para a avaliação da área foliar inoculada.The knowledge of resistance of bean genotypes to pathogens is important to genetic breeding programs. Two methods of bacterial inoculation were tested to evaluate the sensitivity of bean genotypes to common bacterial blight, caused by Xanthomonas axonopodis pv. phaseoli. Leaves of 56 bean genotypes were inoculated by the method of multiple needles and the method of incision with scissors, using the isolated XAP 15497. We classified 21 genotypes as resistant, 13 as moderately resistant, 9 as moderately susceptible, and 13 as

  11. Michael Addition Reaction of Fluorinated Nitro Compounds

    Institute of Scientific and Technical Information of China (English)

    郇凤; 胡华伟; 黄焰根; 陈庆云; 郭勇

    2012-01-01

    The Michael addition reactions of fluorinated nitro compounds with electron deficient olefins to give γ-fiuoro-γ-nitro-esters, nitriles and ketones which bear a fluorinated quaternary carbon center were reported. The reactions were promoted by TMG, affording the desired adducts in acceptable to good yields.

  12. Spontaneous bacterial peritonitis

    Institute of Scientific and Technical Information of China (English)

    Anastasios Koulaouzidis; Shivaram Bhat; Athar A Saeed

    2009-01-01

    Since its initial description in 1964, research has transformed spontaneous bacterial peritonitis (SBP) from a feared disease (with reported mortality of 90%) to a treatable complication of decompensated cirrhosis,albeit with steady prevalence and a high recurrence rate. Bacterial translocation, the key mechanism in the pathogenesis of SBP, is only possible because of the concurrent failure of defensive mechanisms in cirrhosis.Variants of SBP should be treated. Leucocyte esterase reagent strips have managed to shorten the 'tap-toshot' time, while future studies should look into their combined use with ascitic fluid pH. Third generation cephalosporins are the antibiotic of choice because they have a number of advantages. Renal dysfunction has been shown to be an independent predictor of mortality in patients with SBP. Albumin is felt to reduce the risk of renal impairment by improving effective intravascular volume, and by helping to bind proinflammatory molecules. Following a single episode of SBP, patients should have long-term antibiotic prophylaxis and be considered for liver transplantation.

  13. Antimicrobials for bacterial bioterrorism agents.

    Science.gov (United States)

    Sarkar-Tyson, Mitali; Atkins, Helen S

    2011-06-01

    The limitations of current antimicrobials for highly virulent pathogens considered as potential bioterrorism agents drives the requirement for new antimicrobials that are suitable for use in populations in the event of a deliberate release. Strategies targeting bacterial virulence offer the potential for new countermeasures to combat bacterial bioterrorism agents, including those active against a broad spectrum of pathogens. Although early in the development of antivirulence approaches, inhibitors of bacterial type III secretion systems and cell division mechanisms show promise for the future.

  14. The relation of morphology and affinity maturation in germinal centers

    CERN Document Server

    Meyer-Hermann, M

    2002-01-01

    The specific morphology of germinal centers is analyzed in the context of the optimization of the humoral immune response. The relevance of dark and light zones for the affinity maturation process is investigated in the framework of a theoretical model for the germinal center reaction. Especially, it is shown that an intermediate appearance of dark zones in germinal center reactions is advantageous for the process of antibody optimization.

  15. TRIMOLECULAR REACTIONS OF URANIUM HEXAFLUORIDE WITH WATER

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, M.; Becnel, J.; Garrison, S.

    2010-02-25

    The hydrolysis reaction of uranium hexafluoride (UF{sub 6}) is a key step in the synthesis of uranium dioxide (UO{sub 2}) powder for nuclear fuels. Mechanisms for the hydrolysis reactions are studied here with density functional theory and the Stuttgart small-core scalar relativistic pseudopotential and associated basis set for uranium. The reaction of a single UF{sub 6} molecule with a water molecule in the gas phase has been previously predicted to proceed over a relatively sizeable barrier of 78.2 kJ {center_dot} mol{sup -1}, indicating this reaction is only feasible at elevated temperatures. Given the observed formation of a second morphology for the UO{sub 2} product coupled with the observations of rapid, spontaneous hydrolysis at ambient conditions, an alternate reaction pathway must exist. In the present work, two trimolecular hydrolysis mechanisms are studied with density functional theory: (1) the reaction between two UF{sub 6} molecules and one water molecule, and (2) the reaction of two water molecules with a single UF{sub 6} molecule. The predicted reaction of two UF{sub 6} molecules with one water molecule displays an interesting 'fluorine-shuttle' mechanism, a significant energy barrier of 69.0 kJ {center_dot} mol{sup -1} to the formation of UF{sub 5}OH, and an enthalpy of reaction ({Delta}H{sub 298}) of +17.9 kJ {center_dot} mol{sup -1}. The reaction of a single UF{sub 6} molecule with two water molecules displays a 'proton-shuttle' mechanism, and is more favorable, having a slightly lower computed energy barrier of 58.9 kJ {center_dot} mol{sup -1} and an exothermic enthalpy of reaction ({Delta}H{sub 298}) of -13.9 kJ {center_dot} mol{sup -1}. The exothermic nature of the overall UF{sub 6} + 2 {center_dot} H{sub 2}O trimolecular reaction and the lowering of the barrier height with respect to the bimolecular reaction are encouraging; however, the sizable energy barrier indicates further study of the UF{sub 6} hydrolysis reaction

  16. [Small intestine bacterial overgrowth].

    Science.gov (United States)

    Leung Ki, E L; Roduit, J; Delarive, J; Guyot, J; Michetti, P; Dorta, G

    2010-01-27

    Small intestine bacterial overgrowth (SIBO) is a condition characterised by nutrient malabsorption and excessive bacteria in the small intestine. It typically presents with diarrhea, flatulence and a syndrome of malabsorption (steatorrhea, macrocytic anemia). However, it may be asymptomatic in the eldery. A high index of suspicion is necessary in order to differentiate SIBO from other similar presenting disorders such as coeliac disease, lactose intolerance or the irritable bowel syndrome. A search for predisposing factor is thus necessary. These factors may be anatomical (stenosis, blind loop), or functional (intestinal hypomotility, achlorydria). The hydrogen breath test is the most frequently used diagnostic test although it lacks standardisation. The treatment of SIBO consists of eliminating predisposing factors and broad-spectrum antibiotic therapy. PMID:20214190

  17. Studying bacterial multispecies biofilms

    DEFF Research Database (Denmark)

    Røder, Henriette Lyng; Sørensen, Søren Johannes; Burmølle, Mette

    2016-01-01

    The high prevalence and significance of multispecies biofilms have now been demonstrated in various bacterial habitats with medical, industrial, and ecological relevance. It is highly evident that several species of bacteria coexist and interact in biofilms, which highlights the need for evaluating...... the approaches used to study these complex communities. This review focuses on the establishment of multispecies biofilms in vitro, interspecies interactions in microhabitats, and how to select communities for evaluation. Studies have used different experimental approaches; here we evaluate the benefits...... and drawbacks of varying the degree of complexity. This review aims to facilitate multispecies biofilm research in order to expand the current limited knowledge on interspecies interactions. Recent technological advances have enabled total diversity analysis of highly complex and diverse microbial communities...

  18. Bacterial proteases and virulence

    DEFF Research Database (Denmark)

    Frees, Dorte; Brøndsted, Lone; Ingmer, Hanne

    2013-01-01

    Bacterial pathogens rely on proteolysis for variety of purposes during the infection process. In the cytosol, the main proteolytic players are the conserved Clp and Lon proteases that directly contribute to virulence through the timely degradation of virulence regulators and indirectly by providing...... tolerance to adverse conditions such as those experienced in the host. In the membrane, HtrA performs similar functions whereas the extracellular proteases, in close contact with host components, pave the way for spreading infections by degrading host matrix components or interfering with host cell...... signalling to short-circuit host cell processes. Common to both intra- and extracellular proteases is the tight control of their proteolytic activities. In general, substrate recognition by the intracellular proteases is highly selective which is, in part, attributed to the chaperone activity associated...

  19. Call Center ist nicht gleich Call Center

    OpenAIRE

    Baumgartner, Marc; Udris, Ivars

    2005-01-01

    Untersuchungen in 14 Schweizer Call Centers erbrachten vier Call Center-Typen, die sich hinsichtlich Arbeitstätigkeiten und Kommunikationsrichtung voneinander unterscheiden: (a) Beratungs- und Beschwerdemanagement, (b) Informationsmanagement, (c) Auftragsmanagement und (d) Kunden- und Kampagnenmanagement. Dies hat auch Auswirkungen auf die Personalstruktur, -selektion und -entwicklung der Call Center. Es wird der Frage nachgegangen, welche Kompetenzanforderungen in den unterschiedlichen Call ...

  20. Chain reaction

    International Nuclear Information System (INIS)

    Chain Reaction is a work of recent American political history. It seeks to explain how and why America came to depend so heavily on its experts after World War II, how those experts translated that authority into political clout, and why that authority and political discretion declined in the 1970s. The author's research into the internal memoranda of the Atomic Energy Commission substantiates his argument in historical detail. It was not the ravages of American anti-intellectualism, as so many scholars have argued, that brought the experts back down to earth. Rather, their decline can be traced to the very roots of their success after World War II. The need to over-state anticipated results in order to garner public support, incessant professional and bureaucratic specialization, and the sheer proliferation of expertise pushed arcane and insulated debates between experts into public forums at the same time that a broad cross section of political participants found it easier to gain access to their own expertise. These tendencies ultimately undermined the political influence of all experts. (author)

  1. Bacterial Protein-Tyrosine Kinases

    DEFF Research Database (Denmark)

    Shi, Lei; Kobir, Ahasanul; Jers, Carsten;

    2010-01-01

    in exopolysaccharide production, virulence, DNA metabolism, stress response and other key functions of the bacterial cell. BY-kinases act through autophosphorylation (mainly in exopolysaccharide production) and phosphorylation of other proteins, which have in most cases been shown to be activated by tyrosine......Bacteria and Eukarya share essentially the same family of protein-serine/threonine kinases, also known as the Hanks-type kinases. However, when it comes to protein-tyrosine phosphorylation, bacteria seem to have gone their own way. Bacterial protein-tyrosine kinases (BY-kinases) are bacterial...... and highlighted their importance in bacterial physiology. Having no orthologues in Eukarya, BY-kinases are receiving a growing attention from the biomedical field, since they represent a particularly promising target for anti-bacterial drug design....

  2. Molecular approaches for bacterial azoreductases

    Directory of Open Access Journals (Sweden)

    Montira Leelakriangsak

    2013-12-01

    Full Text Available Azo dyes are the dominant types of synthetic dyes, widely used in textiles, foods, leather, printing, tattooing, cosmetics, and pharmaceutical industries. Many microorganisms are able to decolorize azo dyes, and there is increasing interest in biological waste treatment methods. Bacterial azoreductases can cleave azo linkages (-N=N- in azo dyes, forming aromatic amines. This review mainly focuses on employing molecular approaches, including gene manipulation and recombinant strains, to study bacterial azoreductases. The construction of the recombinant protein by cloning and the overexpression of azoreductase is described. The mechanisms and function of bacterial azoreductases can be studied by other molecular techniques discussed in this review, such as RT-PCR, southern blot analysis, western blot analysis, zymography, and muta-genesis in order to understand bacterial azoreductase properties, function and application. In addition, understanding the regulation of azoreductase gene expression will lead to the systematic use of gene manipulation in bacterial strains for new strategies in future waste remediation technologies.

  3. Children's cancer centers

    Science.gov (United States)

    Pediatric cancer center; Pediatric oncology center; Comprehensive cancer center ... Treating childhood cancer is not the same as treating adult cancer. The cancers are different. So are the treatments and the ...

  4. Chemical potential and reaction electronic flux in symmetry controlled reactions.

    Science.gov (United States)

    Vogt-Geisse, Stefan; Toro-Labbé, Alejandro

    2016-07-15

    In symmetry controlled reactions, orbital degeneracies among orbitals of different symmetries can occur along a reaction coordinate. In such case Koopmans' theorem and the finite difference approximation provide a chemical potential profile with nondifferentiable points. This results in an ill-defined reaction electronic flux (REF) profile, since it is defined as the derivative of the chemical potential with respect to the reaction coordinate. To overcome this deficiency, we propose a new way for the calculation of the chemical potential based on a many orbital approach, suitable for reactions in which symmetry is preserved. This new approach gives rise to a new descriptor: symmetry adapted chemical potential (SA-CP), which is the chemical potential corresponding to a given irreducible representation of a symmetry group. A corresponding symmetry adapted reaction electronic flux (SA-REF) is also obtained. Using this approach smooth chemical potential profiles and well defined REFs are achieved. An application of SA-CP and SA-REF is presented by studying the Cs enol-keto tautomerization of thioformic acid. Two SA-REFs are obtained, JA'(ξ) and JA'' (ξ). It is found that the tautomerization proceeds via an in-plane delocalized 3-center 4-electron O-H-S hypervalent bond which is predicted to exist only in the transition state (TS) region. © 2016 Wiley Periodicals, Inc.

  5. Womens Business Center

    Data.gov (United States)

    Small Business Administration — Women's Business Centers (WBCs) represent a national network of nearly 100 educational centers throughout the United States and its territories, which are designed...

  6. Positioning of bacterial chemoreceptors.

    Science.gov (United States)

    Jones, Christopher W; Armitage, Judith P

    2015-05-01

    For optimum growth, bacteria must adapt to their environment, and one way that many species do this is by moving towards favourable conditions. To do so requires mechanisms to both physically drive movement and provide directionality to this movement. The pathways that control this directionality comprise chemoreceptors, which, along with an adaptor protein (CheW) and kinase (CheA), form large hexagonal arrays. These arrays can be formed around transmembrane receptors, resulting in arrays embedded in the inner membrane, or they can comprise soluble receptors, forming arrays in the cytoplasm. Across bacterial species, chemoreceptor arrays (both transmembrane and soluble) are localised to a variety of positions within the cell; some species with multiple arrays demonstrate this variety within individual cells. In many cases, the positioning pattern of the arrays is linked to the need for segregation of arrays between daughter cells on division, ensuring the production of chemotactically competent progeny. Multiple mechanisms have evolved to drive this segregation, including stochastic self-assembly, cellular landmarks, and the utilisation of ParA homologues. The variety of mechanisms highlights the importance of chemotaxis to motile species.

  7. Evolution of Bacterial Suicide

    Science.gov (United States)

    Tchernookov, Martin; Nemenman, Ilya

    2013-03-01

    While active, controlled cellular suicide (autolysis) in bacteria is commonly observed, it has been hard to argue that autolysis can be beneficial to an individual who commits it. We propose a theoretical model that predicts that bacterial autolysis is evolutionarily advantageous to an individualand would fixate in physically structured environments for stationary phase colonies. We perform spatially resolved agent-based simulations of the model, which predict that lower mixing in the environment results in fixation of a higher autolysis rate from a single mutated cell, regardless of the colony's genetic diversity. We argue that quorum sensing will fixate as well, even if initially rare, if it is coupled to controlling the autolysis rate. The model does not predict a strong additional competitive advantage for cells where autolysis is controlled by quorum sensing systems that distinguish self from nonself. These predictions are broadly supported by recent experimental results in B. subtilisand S. pneumoniae. Research partially supported by the James S McDonnell Foundation grant No. 220020321 and by HFSP grant No. RGY0084/2011.

  8. Electromagnetism of Bacterial Growth

    Science.gov (United States)

    Ainiwaer, Ailiyasi

    2011-10-01

    There has been increasing concern from the public about personal health due to the significant rise in the daily use of electrical devices such as cell phones, radios, computers, GPS, video games and television. All of these devices create electromagnetic (EM) fields, which are simply magnetic and electric fields surrounding the appliances that simultaneously affect the human bio-system. Although these can affect the human system, obstacles can easily shield or weaken the electrical fields; however, magnetic fields cannot be weakened and can pass through walls, human bodies and most other objects. The present study was conducted to examine the possible effects of bacteria when exposed to magnetic fields. The results indicate that a strong causal relationship is not clear, since different magnetic fields affect the bacteria differently, with some causing an increase in bacterial cells, and others causing a decrease in the same cells. This phenomenon has yet to be explained, but the current study attempts to offer a mathematical explanation for this occurrence. The researchers added cultures to the magnetic fields to examine any effects to ion transportation. Researchers discovered ions such as potassium and sodium are affected by the magnetic field. A formula is presented in the analysis section to explain this effect.

  9. 76 FR 6486 - Center for Scientific Review; Notice of Closed Meetings

    Science.gov (United States)

    2011-02-04

    ... Scientific Review Special Emphasis Panel; RFA Panel: Topics in Bacterial Pathogenesis. Date: March 7-8, 2011...: Center for Scientific Review Special Emphasis Panel; Small Business: Non-HIV Diagnostics, Food...

  10. 77 FR 61010 - Center for Scientific Review; Notice of Closed Meetings

    Science.gov (United States)

    2012-10-05

    ... Committee: Center for Scientific Review Special Emphasis Panel Topics in Bacterial Pathogenesis. Date...: Non-HIV Microbial Vaccine Development. Date: October 26, 2012. Time: 8:00 a.m. to 6:00 p.m. Agenda:...

  11. AN EXPERIMENTAL ANALYSIS OF BACTERIAL ALLERGY.

    Science.gov (United States)

    Zinsser, H; Tamiya, T

    1926-11-30

    Our experiments have confirmed the fact that the so called bacterial allergies are dependent upon a mechanism which differs materially from that determining true protein anaphylaxis. Anaphylaxis to protein substances of the bacteria probably occurs but plays a relatively unimportant rôle in the phenomena of infection. The bacterial allergies, however, are of great importance since they develop rapidly and render the infected animal highly vulnerable to products of the bacterial growth which are relatively innocuous for the normal animal. Neither the type-specific carbohydrate "residue antigens" (the "soluble specific substances" of Avery and Heidelberger) nor the antibodies reacting with them play any part whatever in bacterial allergy, and since these type-specific substances represent the haptophore groups of the whole bacteria by which they react with the agglutinins, precipitins, sensitizers, etc., of immune serum, allergy, as previously determined by Mackenzie and Woo, is in no way related to that phase of resistance which is determined by these antibodies. This does not, however, preclude the possibility that allergic hypersusceptibility may not in some way be related to other factors of resistance more definitely associated with cellular rather than with intravascular reactions. Our previous studies with Jennings and Ward in tuberculosis point in this direction (20). Guinea pigs can be actively sensitized with all the bacteria with which we have worked when repeated injections of whole bacteria or of the protein (nucleoprotein) fraction are administered. Large amounts of the latter are necessary since these materials are indifferent antigens, possibly because of the severe manipulations necessary in their production. Sensitiveness develops usually within 10 days after the first dose and increases with continued treatment for 3 or 4 weeks. Sensitiveness is relatively specific, by which we mean that there is a definite specificity which, however, in highly

  12. Student Success Center Toolkit

    Science.gov (United States)

    Jobs For the Future, 2014

    2014-01-01

    "Student Success Center Toolkit" is a compilation of materials organized to assist Student Success Center directors as they staff, launch, operate, and sustain Centers. The toolkit features materials created and used by existing Centers, such as staffing and budgeting templates, launch materials, sample meeting agendas, and fundraising…

  13. Measurement of Behavioral Evolution in Bacterial Populations

    Science.gov (United States)

    Austin, Robert

    2013-03-01

    A curious aspect of bacterial behavior under stress is the induction of filamentation: the anomalous growth of certain bacteria in which cells continue to elongate but do not divide into progeny. We show that E.coli under the influence of the genotoxic antibiotic ciprofloxacin have robust filamentous growth, which provides individual bacteria a mesoscopic niche for evolution until resistant progeny can bud off and propagate. Hence, filamentation is a form of genomic amplification where even a single, isolated bacteria can have access to multiple genomes. We propose a model that predicts that the first arrival time of the normal sized progeny should follow a Gompertz distribution with the mean first arrival time proportional to the elongation rate of filament. These predictions agree with our experimental measurements. Finally, we suggest bacterial filament growth and budding has many similarities to tumor growth and metastasis and can serve as a simpler model to study those complicated processes. Sponsored by the NCI/NIH Physical Sciences Oncology Centers

  14. The structure and function of bacterial light-harvesting complexes.

    Science.gov (United States)

    Law, Christopher J; Roszak, Aleksander W; Southall, June; Gardiner, Alastair T; Isaacs, Neil W; Cogdell, Richard J

    2004-01-01

    The harvesting of solar radiation by purple photosynthetic bacteria is achieved by circular, integral membrane pigment-protein complexes. There are two main types of light-harvesting complex, termed LH2 and LH1, that function to absorb light energy and to transfer that energy rapidly and efficiently to the photochemical reaction centres where it is trapped. This mini-review describes our present understanding of the structure and function of the purple bacterial light-harvesting complexes.

  15. Bacterial Flora of Osteoradionecrosis Detected by Molecular techniques

    OpenAIRE

    2006-01-01

    The following is a report of a study undertaken to identify the bacterial species in bone samples from patients suffering from osteoradionecrosis. This was done using polymerase chain reaction (PCR), cloning and sequencing techniques, where 16S rRNA was the gene used for analysis. The results from two patient samples will be presented. As far as we know, this is the first study that includes molecular genetic techniques to detect bacteria associated with osteoradionecrosis.

  16. Bacterial Communities: Interactions to Scale

    Science.gov (United States)

    Stubbendieck, Reed M.; Vargas-Bautista, Carol; Straight, Paul D.

    2016-01-01

    In the environment, bacteria live in complex multispecies communities. These communities span in scale from small, multicellular aggregates to billions or trillions of cells within the gastrointestinal tract of animals. The dynamics of bacterial communities are determined by pairwise interactions that occur between different species in the community. Though interactions occur between a few cells at a time, the outcomes of these interchanges have ramifications that ripple through many orders of magnitude, and ultimately affect the macroscopic world including the health of host organisms. In this review we cover how bacterial competition influences the structures of bacterial communities. We also emphasize methods and insights garnered from culture-dependent pairwise interaction studies, metagenomic analyses, and modeling experiments. Finally, we argue that the integration of multiple approaches will be instrumental to future understanding of the underlying dynamics of bacterial communities. PMID:27551280

  17. Bacterial Communities: Interactions to Scale

    Directory of Open Access Journals (Sweden)

    Reed M. Stubbendieck

    2016-08-01

    Full Text Available In the environment, bacteria live in complex multispecies communities. These communities span in scale from small, multicellular aggregates to billions or trillions of cells within the gastrointestinal tract of animals. The dynamics of bacterial communities are determined by pairwise interactions that occur between different species in the community. Though interactions occur between a few cells at a time, the outcomes of these interchanges have ramifications that ripple through many orders of magnitude, and ultimately affect the macroscopic world including the health of host organisms. In this review we cover how bacterial competition influences the structures of bacterial communities. We also emphasize methods and insights garnered from culture-dependent pairwise interaction studies, metagenomic analyses, and modeling experiments. Finally, we argue that the integration of multiple approaches will be instrumental to future understanding of the underlying dynamics of bacterial communities.

  18. Meningitis bacteriana Bacterial meningitis

    Directory of Open Access Journals (Sweden)

    Ana Teresa Alvarado Guevara

    2006-03-01

    causales son virales lo cual conlleva a las diferentes sub-clasificaciones. También en ciertos casos puede ser ocasionada por hongos, bacterias atípicas, micobacterias y parásitos.In Costa Rica the bacterial meningitis had turn into a high-priority subject in which to monitoring epidemiologist. It had been talked about in the last months, to dice an increase in the attention is published of this subject, due to this phenomenon it becomes necessary to make a revision of topic. Meningitis is an inflammation of leptomeninges and colonization of the subarachnoid cerebrospinal fluid (LCR due to different agents, which produces meningeal symptoms (ex. migraine, neck rigidity, and photophobia and pleocytosis in LCR. De pending on the variables to take into account is possible to group it in different classifications, taking into account the time of evolution are possible to be divided in acute or chronic, to first with few hours or days of beginning of the symptoms, whereas the chronicle also presents a silence course but of the disease of approximately 4 weeks of instauration. There is a difference according to its etiologic agent; they can be infectious and non-infectious. Examples of common non-infectious causes include medications (ex, nonsteroidal anti-inflammatory drugs, and antibiotics and carcinomatosis. A classification exists as well according to the causal agent. The acute bacterial meningitis remarks a bacterial origin of the syndrome, which characterizes by the by an acute onset of meningeal symptoms and neutrophilic pleocytosis. Each one of the bacteriological agents, parasitic or fungus finishes by characterizing the different presentations of the clinical features (ex, meningocóccica meningitis, Cryptococcus meningitis. Finally, there is also the aseptic meningitis, denominated in this form because it’s nonpyogenic cellular response caused by many types of agents. The patients show an acute beginning of symptoms, fever and lymphocytic pleocytosis. After

  19. Bacterial Culture of Neonatal Sepsis

    OpenAIRE

    AH Movahedian; R Moniri; Z Mosayebi

    2006-01-01

    Neonatal bacterial sepsis is one of the major cause of morbidity and mortality in neonates. This retrospective study was performed to determine the incidence of bacterial sepsis with focus on Gram negative organisms in neonates admitted at Beheshti Hospital in Kashan, during a 3-yr period, from September 2002 to September 2005. Blood culture was performed on all neonates with risk factors or signs of suggestive sepsis. Blood samples were cultured using brain heart infusion (BHI) broth accordi...

  20. Mast cells in bacterial infections

    OpenAIRE

    Rönnberg, Elin

    2014-01-01

    Mast cells are implicated in immunity towards bacterial infection, but the molecular mechanisms by which mast cells contribute to the host response are only partially understood. Previous studies have examined how mast cells react to purified bacterial cell wall components, such as peptidoglycan and lipopolysaccharide. To investigate how mast cells react to live bacteria we co-cultured mast cells and the gram-positive bacteria Streptococcus equi (S. equi) and Staphylococcus aureus (S. aureus)...

  1. Bacterial Alkaloids Prevent Amoebal Predation.

    Science.gov (United States)

    Klapper, Martin; Götze, Sebastian; Barnett, Robert; Willing, Karsten; Stallforth, Pierre

    2016-07-25

    Bacterial defense mechanisms have evolved to protect bacteria against predation by nematodes, predatory bacteria, or amoebae. We identified novel bacterial alkaloids (pyreudiones A-D) that protect the producer, Pseudomonas fluorescens HKI0770, against amoebal predation. Isolation, structure elucidation, total synthesis, and a proposed biosynthetic pathway for these structures are presented. The generation of P. fluorescens gene-deletion mutants unable to produce pyreudiones rendered the bacterium edible to a variety of soil-dwelling amoebae. PMID:27294402

  2. Bacterial cellulose/boehmite composites

    International Nuclear Information System (INIS)

    Composites based on bacterial cellulose membranes and boehmite were obtained. SEM results indicate that the bacterial cellulose (BC) membranes are totally covered by boehmite and obtained XRD patterns suggest structural changes due to this boehmite addition. Thermal stability is accessed through TG curves and is dependent on boehmite content. Transparency is high comparing to pure BC as can be seen through UV-vis absorption spectroscopy. (author)

  3. Respiratory hypersensitivity reactions to NSAIDs in Europe

    DEFF Research Database (Denmark)

    Makowska, J S; Burney, P; Jarvis, D;

    2016-01-01

    BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most prevalent drugs inducing hypersensitivity reactions. The aim of this analysis was to estimate the prevalence of NSAID-induced respiratory symptoms in population across Europe and to assess its association with upper...... and lower respiratory tract disorders. METHODS: The GA(2) LEN survey was conducted in 22 centers in 15 European countries. Each of 19 centers selected random samples of 5000 adults aged 15-74 from their general population, and in three centers (Athens, Munich, Oslo), a younger population was sampled...... prevalence of NSAID-induced dyspnea was 1.9% and was highest in the three Polish centers [Katowice (4.9%), Krakow (4.8%), and Lodz (4.4%)] and lowest in Skopje, (0.9%), Amsterdam (1.1%), and Umea (1.2%). In multivariate analysis, the prevalence of respiratory reactions to NSAIDs was higher in participants...

  4. Clinical efficacy of dalbavancin for the treatment of acute bacterial skin and skin structure infections (ABSSSI)

    OpenAIRE

    Leuthner KD; Buechler KA; Kogan D; Saguros A; Lee HS

    2016-01-01

    Kimberly D Leuthner,1 Kristin A Buechler,1 David Kogan,1 Agafe Saguros,1 H Stephen Lee2 1Department of Pharmaceutical Services, University Medical Center of Southern Nevada, Las Vegas, NV, USA; 2Roseman University of Health Sciences College of Pharmacy, Henderson, NV, USA Abstract: Acute bacterial skin and skin structure infections (ABSSSI) are a common disease causing patients to seek treatment through the health care system. With the continued increase of drug-resistant bacterial pathogen...

  5. Method for predicting enzyme-catalyzed reactions

    Science.gov (United States)

    Hlavacek, William S.; Unkefer, Clifford J.; Mu, Fangping; Unkefer, Pat J.

    2013-03-19

    The reactivity of given metabolites is assessed using selected empirical atomic properties in the potential reaction center. Metabolic reactions are represented as biotransformation rules. These rules are generalized from the patterns in reactions. These patterns are not unique to reactants but are widely distributed among metabolites. Using a metabolite database, potential substructures are identified in the metabolites for a given biotransformation. These substructures are divided into reactants or non-reactants, depending on whether they participate in the biotransformation or not. Each potential substructure is then modeled using descriptors of the topological and electronic properties of atoms in the potential reaction center; molecular properties can also be used. A Support Vector Machine (SVM) or classifier is trained to classify a potential reactant as a true or false reactant using these properties.

  6. C-反应蛋白检测在小儿细菌性肺炎与支原体肺炎中的临床比较%Clinical value of detection of C-reaction protein in diagnosis of pediatric bacterial pneumonia and Mycoplasma pneumonia:a comparative study

    Institute of Scientific and Technical Information of China (English)

    石丰月

    2013-01-01

    OBJECTIVE To study the clinical value of C-reactie protein (CRP) detection in diagnosis of the pediatric bacterial pneumonia and the Mycoplasma pneumonia so as to guide the diagnosis of infantile pneumonia.METHODS The children with bacterial pneumonia (the bacterial pneumonia group) and the children with Mycoplasma pneumonia (the Mycoplasma pneumonia group),who were treated in the pediatrics department from Sep 2010 to Sep 2012,were enrolled in the study,the healthy children receiving the medical examination (the control group)were also selected,with 80 cases in each group,then the change of CRP level was determined.RESULTS The CRP level of the control group was (3.24 ±0.45)mg/L,the bacterial pneumonia group before treatment (44.03±5.83) mg/L,the bacterial pneumonia group 3 days after the treatment (15.12±6.21) mg/L,the Mycoplasma pneumonia group before treatment (13.97±4.96) mg/L,the Mycoplasma pneumonia group 3 days after the treatment (5.29 ± 2.33) mg/L,the CRP level of the bacterial pneumonia group and the Mycoplasma pneumonia group before the treatment was significantly higher than that of the control group (P<0.05),the CRP level of the bacterial pneumonia group was higher than that of the Mycoplasma pneumonia group (P<0.05),the CRP level of the bacterial pneumonia group 3 days after treatment was higher than that of the Mycoplasma pneumonia group (P<0.05),the difference in the CRP level before and after the treatment between the bacterial pneumonia group and the Mycoplasma pneumonia group was statistically significant (P< 0.05).The positive rates of the CRP of the bacterial pneumonia group were 100.00% before the treatment and 52.50% 3 days after the treatment,which were respectively 66.25 % and 21.25 % in the Mycoplasma pneumonia group,the difference in the positive rate before and after the treatment between the bacterial pneumonia group and the Mycoplasmapneumonia group was statistically significant (P<0.05).CONCLUSION The positive

  7. Effect of cisapride on intestinal bacterial and endotoxin translocation in cirrhosis

    Institute of Scientific and Technical Information of China (English)

    Shun-Cai Zhang; Wei Wang; Wei-Ying Ren; Bo-Ming He; Kang Zhou; Wu-Nan Zhu

    2003-01-01

    AIM: To investigate the effects of cisapride on intestinal bacterial overgrowth (IBO), bacterial and endotoxin translocation, intestinal transit and permeability in cirrhotic rats.METHODS: All animals were assessed with variables including bacterial and endotoxin translocation, intestinal bacterial overgrowth, intestinal transit and permeability.Bacterial translocation (BT) was assessed by bacterial culture of MLN, liver and spleen, IBO by a jejunal bacterial count of the specific organism, intestinal permeability by determination of the 24-hour urinary 99mTc-DTPA excretion and intestinal transit by measurement of the distribution of 51Cr in the intestine.RESULTS: Bacterial translocation (BT) and IBO was found in 48 % and 80 % cirrhotic rats respectively and none in control rats. Urinary excretion of 99mTc-DTPA in cirrhotic rats with BT (22.2±7.8) was greater than these without BT (10.5±2.9). Intestinal transit (geometric center ratio) was significantly delayed in cirrhotic rats (0.31±0.06) and further more delayed in cirrhotic rats with BT (0.24±0.06) than these without BT (0.38±0.11). Cirrhotic rats with IBO had significantly higher rates of intestinal bacterial and endotoxin translocation, slower intestinal transit time and higher intestinal permeability than those without IBO. It was also found that BT was closely associated with IBO and the injury of intestinal barrier. Compared with the placebo group,cisapride-treated rats had lower rates of bacterial/endotoxin translocation and IBO, which was closely associated with increased intestinal transit and improved intestinal permeability by cisapride.CONCLUSION: These results indicate that endotoxin and bacterial translocation in cirrhotic rats may be attributed to IBO and increased intestinal permeability. Cisapride that accelerates intestinal transit and improve intestinal permeability might be helpful in preventing intestinal bacterial and endotoxin translocation.

  8. Molecular Phylogenetic Diversity and Spatial Distribution of Bacterial Communities in Cooling Stage during Swine Manure Composting

    OpenAIRE

    Guo, Yan; Zhang, Jinliang; Yan, Yongfeng; Wu, Jian; Zhu, Nengwu; Deng, Changyan

    2015-01-01

    Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and subsequent sub-cloning and sequencing were used in this study to analyze the molecular phylogenetic diversity and spatial distribution of bacterial communities in different spatial locations during the cooling stage of composted swine manure. Total microbial DNA was extracted, and bacterial near full-length 16S rRNA genes were subsequently amplified, cloned, RFLP-screened, and sequenced. A total of 420 positive ...

  9. Diversity surveys of soil bacterial community by cultivation-based methods and molecular fingerprinting techniques

    Institute of Scientific and Technical Information of China (English)

    LUO Hai-feng; QI Hong-yan; ZHANG Hong-xun

    2004-01-01

    By combining the cultivation methods with molecular fingerprinting techniques, the diversity surveys of soil bacterial community in 13 areas of China were carried out. The cultivable heterotrophic diversity was investigated by colony morphology on solid LB medium. Genetic diversity was measured as bands on denaturing gradient gel electrophoresis(DGGE) by the extraction and purification of the total soil DNA, and amplification of bacterial 16S rDNA fragments by polymerase chain reaction ( PCR). The Shannon-Wiener indices of diversity (H), richness (S)and evenness( EH ) were employed to estimate the diversity of soil bacterial community. The results showed that there was an obvious diversification existed in soil from the different areas. However, the genetic diversity estimated by PCR-DGGE can provide more comprehensive information on bacterial community than the cultivation-based methods. Therefore, it is suggested to combine the traditional methods with genetic fingerprinting techniques to survey and estimate soil bacterial diversity.

  10. Factors influencing neurological outcome of children with bacterial meningitis at the emergency department.

    Science.gov (United States)

    Bargui, Fatiha; D'Agostino, Irene; Mariani-Kurkdjian, Patricia; Alberti, Corinne; Doit, Catherine; Bellier, Nathalie; Morin, Laurence; Galli Gibertini, Giuliano; Smail, Assia; Zanin, Anna; Lorrot, Mathie; Dauger, Stéphane; Neve, Mathieu; Faye, Albert; Armoogum, Priscilla; Bourrillon, Antoine; Bingen, Edouard; Mercier, Jean-Christophe; Bonacorsi, Stéphane; Nigrovic, Lise E; Titomanlio, Luigi

    2012-09-01

    We performed a cohort study of children who survived bacterial meningitis after the neonatal period at a single pediatric center in France over a 10-year period (1995-2004) to identify predictors of death and long-term neurological deficits in children with bacterial meningitis. We performed multivariate regression to determine independent predictors of death and neurologic deficits. We identified 101 children with bacterial meningitis of which 19 died during initial hospitalization. Need for mechanical ventilation [hazard ratio (HR) 11.5, 95 % confidence interval (CI) 2.4-55.5)] and thrombocytopenia defined as a platelet count highest risk.

  11. Catalysis of Photochemical Reactions.

    Science.gov (United States)

    Albini, A.

    1986-01-01

    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  12. The Human Vaginal Bacterial Biota and Bacterial Vaginosis

    Directory of Open Access Journals (Sweden)

    Sujatha Srinivasan

    2008-01-01

    Full Text Available The bacterial biota of the human vagina can have a profound impact on the health of women and their neonates. Changes in the vaginal microbiota have been associated with several adverse health outcomes including premature birth, pelvic inflammatory disease, and acquisition of HIV infection. Cultivation-independent molecular methods have provided new insights regarding bacterial diversity in this important niche, particularly in women with the common condition bacterial vaginosis (BV. PCR methods have shown that women with BV have complex communities of vaginal bacteria that include many fastidious species, particularly from the phyla Bacteroidetes and Actinobacteria. Healthy women are mostly colonized with lactobacilli such as Lactobacillus crispatus, Lactobacillus jensenii, and Lactobacillus iners, though a variety of other bacteria may be present. The microbiology of BV is heterogeneous. The presence of Gardnerella vaginalis and Atopobium vaginae coating the vaginal epithelium in some subjects with BV suggests that biofilms may contribute to this condition.

  13. On thermonuclear reaction rates

    OpenAIRE

    Hans J. Haubold; Mathai, Arak Mathai

    1996-01-01

    Nuclear reactions govern major aspects of the chemical evolution of galaxies and stars. Analytic study of the reaction rates and reaction probability integrals is attempted here. Exact expressions for the reaction rates and reaction probability integrals for nuclear reactions in the cases of nonresonant, modified nonresonant, screened nonresonant and resonant cases are given. These are expressed in terms of H-functions, G-functions and in computable series forms. Computational aspects are als...

  14. Bacterial tactic responses.

    Science.gov (United States)

    Armitage, J P

    1999-01-01

    Many, if not most, bacterial species swim. The synthesis and operation of the flagellum, the most complex organelle of a bacterium, takes a significant percentage of cellular energy, particularly in the nutrient limited environments in which many motile species are found. It is obvious that motility accords cells a survival advantage over non-motile mutants under normal, poorly mixed conditions and is an important determinant in the development of many associations between bacteria and other organisms, whether as pathogens or symbionts and in colonization of niches and the development of biofilms. This survival advantage is the result of sensory control of swimming behaviour. Although too small to sense a gradient along the length of the cell, and unable to swim great distances because of buffetting by Brownian motion and the curvature resulting from a rotating flagellum, bacteria can bias their random swimming direction towards a more favourable environment. The favourable environment will vary from species to species and there is now evidence that in many species this can change depending on the current physiological growth state of the cell. In general, bacteria sense changes in a range of nutrients and toxins, compounds altering electron transport, acceptors or donors into the electron transport chain, pH, temperature and even the magnetic field of the Earth. The sensory signals are balanced, and may be balanced with other sensory pathways such as quorum sensing, to identify the optimum current environment. The central sensory pathway in this process is common to most bacteria and most effectors. The environmental change is sensed by a sensory protein. In most species examined this is a transmembrane protein, sensing the external environment, but there is increasing evidence for additional cytoplasmic receptors in many species. All receptors, whether sensing sugars, amino acids or oxygen, share a cytoplasmic signalling domain that controls the activity of a

  15. Day Care Centers

    Data.gov (United States)

    Department of Homeland Security — This database contains locations of day care centers for 50 states and Washington D.C. and Puerto Rico. The dataset only includes center based day care locations...

  16. Poison Control Centers

    Science.gov (United States)

    ... 1222 immediately. Name State American Association of Poison Control Centers Address AAPCC Central Office NOT A POISON ... not for emergency use. Arkansas ASPCA Animal Poison Control Center Address 1717 S. Philo Road, Suite 36 Urbana, ...

  17. New Mexico Convention Centers

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This dataset provides an initial version of the locations of convention centers in New Mexico, in point form, with limited attributes, compiled using available data...

  18. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Education / Safety Education Centers En Español Carbon Monoxide Information Center The Invisible Killer Carbon monoxide, also known ... Install one and check its batteries regularly. View Information About CO Alarms Other CO Topics Safety Tips ...

  19. Hydrologic Engineering Center

    Data.gov (United States)

    Federal Laboratory Consortium — The Hydrologic Engineering Center (HEC), an organization within the Institute for Water Resources, is the designated Center of Expertise for the U.S. Army Corps of...

  20. RSW Cell Centered Grids

    Data.gov (United States)

    National Aeronautics and Space Administration — New cell centered grids are generated to complement the node-centered ones uploaded. Six tarballs containing the coarse, medium, and fine mixed-element and pure...

  1. Tornadoes: A Center Approach.

    Science.gov (United States)

    Christman-Rothlein, Liz; Meinbach, Anita M.

    1981-01-01

    Information is given on how to put together a learning center. Discusses information and activity packets for a complete learning center on tornadoes including objectives, directions, materials, photographs of physical arrangements, and posttest. (DC)

  2. BKG Data Center

    Science.gov (United States)

    Thorandt, Volkmar; Wojdziak, Reiner

    2013-01-01

    This report summarizes the activities and background information of the IVS Data Center for the year 2012. Included is information about functions, structure, technical equipment, and staff members of the BKG Data Center.

  3. ACTS data center

    Science.gov (United States)

    Syed, Ali; Vogel, Wolfhard J.

    1993-01-01

    Viewgraphs on ACTS Data Center status report are included. Topics covered include: ACTS Data Center Functions; data flow overview; PPD flow; RAW data flow; data compression; PPD distribution; RAW Data Archival; PPD Audit; and data analysis.

  4. NIH Clinical Centers

    Data.gov (United States)

    Federal Laboratory Consortium — The NIH Clinical Center consists of two main facilities: The Mark O. Hatfield Clinical Research Center, which opened in 2005, houses inpatient units, day hospitals,...

  5. Center for Functional Nanomaterials

    Data.gov (United States)

    Federal Laboratory Consortium — The Center for Functional Nanomaterials (CFN) explores the unique properties of materials and processes at the nanoscale. The CFN is a user-oriented research center...

  6. New Treatments for Bacterial Keratitis

    Directory of Open Access Journals (Sweden)

    Raymond L. M. Wong

    2012-01-01

    Full Text Available Purpose. To review the newer treatments for bacterial keratitis. Data Sources. PubMed literature search up to April 2012. Study Selection. Key words used for literature search: “infectious keratitis”, “microbial keratitis”, “infective keratitis”, “new treatments for infectious keratitis”, “fourth generation fluoroquinolones”, “moxifloxacin”, “gatifloxacin”, “collagen cross-linking”, and “photodynamic therapy”. Data Extraction. Over 2400 articles were retrieved. Large scale studies or publications at more recent dates were selected. Data Synthesis. Broad spectrum antibiotics have been the main stay of treatment for bacterial keratitis but with the emergence of bacterial resistance; there is a need for newer antimicrobial agents and treatment methods. Fourth-generation fluoroquinolones and corneal collagen cross-linking are amongst the new treatments. In vitro studies and prospective clinical trials have shown that fourth-generation fluoroquinolones are better than the older generation fluoroquinolones and are as potent as combined fortified antibiotics against common pathogens that cause bacterial keratitis. Collagen cross-linking was shown to improve healing of infectious corneal ulcer in treatment-resistant cases or as an adjunct to antibiotics treatment. Conclusion. Fourth-generation fluoroquinolones are good alternatives to standard treatment of bacterial keratitis using combined fortified topical antibiotics. Collagen cross-linking may be considered in treatment-resistant infectious keratitis or as an adjunct to antibiotics therapy.

  7. Center of buoyancy definition

    International Nuclear Information System (INIS)

    The center of buoyancy of an arbitrary shaped body is defined in analogy to the center of gravity. The definitions of the buoyant force and center of buoyancy in terms of integrals over the area of the body are converted to volume integrals and shown to have simple intuitive interpretations

  8. Bacterial contribution to iodine volatilization in the environment

    International Nuclear Information System (INIS)

    The roles of microorganisms in iodine volatilization from the environment were studied. More than 100 bacterial strains were isolated from various environments such as soils, seawater and marine sediments, and were examined their capacities for volatilizing iodine. Approximately 40% of these bacteria showed significant capacities for volatilizing iodine. Gas chromatographic determinations revealed that the chemical species of gaseous iodine is methyl iodide (CH3I). Phylogenetic analysis based on 16S ribosomal DNA showed that these 'iodine-volatilizing bacteria' are widely distributed through the bacterial domain. The iodide-methylating reaction was mediated by an enzyme protein with S-adenosyl-L-methionine (SAM) as the methyl donor. We then estimated bacterial contribution to iodine volatilization from soils. Iodine in soils was volatilized mainly as CH3I. CH3I emission was enhanced in the presence of glucose or yeast extract, but was inhibited by autoclaving of soils. Little CH3I was produced under anaerobic conditions. Furthermore, the addition of streptomycin and tetracycline, antibiotics which inhibit bacterial growth, strongly inhibited CH3I emission, while a fungal inhibitor cycloheximide caused little effect. These results suggest that iodine in soils is volatilized as CH3I mainly by the action of aerobic soil bacteria. Similar experiment was carried out by using sea water samples. The emission of iodine from sea waters occurred biologically, and bacterial (and also other microbial) contribution was confirmed. Our results suggest that iodine is methylated and volatilized into the atmosphere as a result of bacterial activities. Since bacteria are so abundant and widespread in the environments, they may significantly contribute to global iodine volatilization. This indicates that if 129I would be released from nuclear facilities, weapons testing or ground storage of nuclear wastes, the pathway of volatilization by bacteria should be considered in the

  9. Antibiotic resistance of bacterial biofilms

    DEFF Research Database (Denmark)

    Hoiby, N.; Bjarnsholt, T.; Givskov, M.;

    2010-01-01

    A biofilm is a structured consortium of bacteria embedded in a self-produced polymer matrix consisting of polysaccharide, protein and DNA. Bacterial biofilms cause chronic infections because they show increased tolerance to antibiotics and disinfectant chemicals as well as resisting phagocytosis...... and other components of the body's defence system. The persistence of, for example, staphylococcal infections related to foreign bodies is due to biofilm formation. Likewise, chronic Pseudomonas aeruginosa lung infection in cystic fibrosis patients is caused by biofilm-growing mucoid strains....... Characteristically, gradients of nutrients and oxygen exist from the top to the bottom of biofilms and these gradients are associated with decreased bacterial metabolic activity and increased doubling times of the bacterial cells; it is these more or less dormant cells that are responsible for some of the tolerance...

  10. Phylogenetic organization of bacterial activity.

    Science.gov (United States)

    Morrissey, Ember M; Mau, Rebecca L; Schwartz, Egbert; Caporaso, J Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J; Liu, Cindy M; Hayer, Michaela; McHugh, Theresa A; Marks, Jane C; Price, Lance B; Hungate, Bruce A

    2016-09-01

    Phylogeny is an ecologically meaningful way to classify plants and animals, as closely related taxa frequently have similar ecological characteristics, functional traits and effects on ecosystem processes. For bacteria, however, phylogeny has been argued to be an unreliable indicator of an organism's ecology owing to evolutionary processes more common to microbes such as gene loss and lateral gene transfer, as well as convergent evolution. Here we use advanced stable isotope probing with (13)C and (18)O to show that evolutionary history has ecological significance for in situ bacterial activity. Phylogenetic organization in the activity of bacteria sets the stage for characterizing the functional attributes of bacterial taxonomic groups. Connecting identity with function in this way will allow scientists to begin building a mechanistic understanding of how bacterial community composition regulates critical ecosystem functions. PMID:26943624

  11. Bacterial Degradation of Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Qing X. Li

    2009-01-01

    Full Text Available Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms.

  12. Clinical applications of bacterial glycoproteins.

    Science.gov (United States)

    Fulton, Kelly M; Smith, Jeffrey C; Twine, Susan M

    2016-01-01

    There is an ongoing race between bacterial evolution and medical advances. Pathogens have the advantages of short generation times and horizontal gene transfer that enable rapid adaptation to new host environments and therapeutics that currently outpaces clinical research. Antibiotic resistance, the growing impact of nosocomial infections, cancer-causing bacteria, the risk of zoonosis, and the possibility of biowarfare all emphasize the increasingly urgent need for medical research focussed on bacterial pathogens. Bacterial glycoproteins are promising targets for alternative therapeutic intervention since they are often surface exposed, involved in host-pathogen interactions, required for virulence, and contain distinctive glycan structures. The potential exists to exploit these unique structures to improve clinical prevention, diagnosis, and treatment strategies. Translation of the potential in this field to actual clinical impact is an exciting prospect for fighting infectious diseases. PMID:26971465

  13. Allergic reactions in salmonellosis depends on the Serotype of pathogens

    DEFF Research Database (Denmark)

    Mkrtchyan, M.S.; Zakaryan, М. K.; Mnatsakanyan, А. А.;

    2013-01-01

    that bacterial infections in early life may help to inhibit excessive allergic Th2 reactions by angling the immune system towards Th1 responses. However, it is known that infections can also cause the exacerbation of allergic reactions. Skewing of response away from Treg cells may lead to the onset and....../or progression of autoimmune diseases in humans. It is also thought that there is a high probability that infectious gastroenteritis increases the risk of subsequent autoimmune and allergic diseases....

  14. A unified description of the electrochemical, charge distribution, and spectroscopic properties of the special-pair radical cation in bacterial photosynthesis.

    Science.gov (United States)

    Reimers, Jeffrey R; Hush, Noel S

    2004-04-01

    We apply our four-state 70-vibration vibronic-coupling model for the properties of the photosynthetic special-pair radical cation to: (1) interpret the observed correlations between the midpoint potential and the distribution of spin density between the two bacteriochlorophylls for 30 mutants of Rhodobacter sphaeroides, (2) interpret the observed average intervalence hole-transfer absorption energies as a function of spin density for six mutants, and (3) simulate the recently obtained intervalence electroabsorption Stark spectrum of the wild-type reaction center. While three new parameters describing the location of the sites of mutation with respect to the special pair are required to describe the midpoint-potential data, a priori predictions are made for the transition energies and the Stark spectrum. In general, excellent predictions are made of the observed quantities, with deviations being typically of the order of twice the experimental uncertainties. A unified description of many chemical and spectroscopic properties of the bacterial reaction center is thus provided. Central to the analysis is the assumption that the perturbations made to the reaction center, either via mutations of protein residues or by application of an external electric field, act only to independently modify the oxidation potentials of the two halves of the special pair and hence the redox asymmetry E0. While this appears to be a good approximation, clear evidence is presented that effects of mutation can be more extensive than what is allowed for. A thorough set of analytical equations describing the observed properties is obtained using the Born-Oppenheimer adiabatic approximation. These equations are generally appropriate for intervalence charge-transfer problems and include, for the first time, full treatment of both symmetric and antisymmetric vibrational motions. The limits of validity of the adiabatic approach to the full nonadiabatic problem are obtained.

  15. Practice Gaps: Drug Reactions.

    Science.gov (United States)

    Wolverton, Stephen E

    2016-07-01

    The term "drug reactions" is relevant to dermatology in three categories of reactions: cutaneous drug reactions without systemic features, cutaneous drug reactions with systemic features, and systemic drugs prescribed by the dermatologist with systematic adverse effects. This article uses examples from each of these categories to illustrate several important principles central to drug reaction diagnosis and management. The information presented will help clinicians attain the highest possible level of certainty before making clinical decisions. PMID:27363888

  16. Disease notes - Bacterial root rot

    Science.gov (United States)

    Bacterial root rot initiated by lactic acid bacteria, particularly Leuconostoc, occurs every year in Idaho sugarbeet fields. Hot fall weather seems to make the problem worse. Although Leuconostoc initiates the rot, other bacteria and yeast frequently invade the tissue as well. The acetic acid bac...

  17. Biotechnological applications of bacterial cellulases

    Directory of Open Access Journals (Sweden)

    Esther Menendez

    2015-08-01

    Full Text Available Cellulases have numerous applications in several industries, including biofuel production, food and feed industry, brewing, pulp and paper, textile, laundry, and agriculture.Cellulose-degrading bacteria are widely spread in nature, being isolated from quite different environments. Cellulose degradation is the result of a synergic process between an endoglucanase, an exoglucanase and a,β-glucosidase. Bacterial endoglucanases degrade ß-1,4-glucan linkages of cellulose amorphous zones, meanwhile exoglucanases cleave the remaining oligosaccharide chains, originating cellobiose, which is hydrolyzed by ß-glucanases. Bacterial cellulases (EC 3.2.1.4 are comprised in fourteen Glycosil Hydrolase families. Several advantages, such as higher growth rates and genetic versatility, emphasize the suitability and advantages of bacterial cellulases over other sources for this group of enzymes. This review summarizes the main known cellulolytic bacteria and the best strategies to optimize their cellulase production, focusing on endoglucanases, as well as it reviews the main biotechnological applications of bacterial cellulases in several industries, medicine and agriculture.

  18. A Program Against Bacterial Bioterrorism

    DEFF Research Database (Denmark)

    Kemp, Michael; Dargis, Rimtas; Andresen, Keld;

    2012-01-01

    In 2002 it was decided to establish laboratory facilities in Denmark for diagnosing agents associated with bioterrorism in order to make an immediate appropriate response to the release of such agents possible. Molecular assays for detection of specific agents and molecular and proteomic techniques...... for bacterial infections not associated with bioterrorism that are difficult to culture or identify....

  19. Molecular Mechanisms Underlying Bacterial Persisters

    DEFF Research Database (Denmark)

    Maisonneuve, Etienne; Gerdes, Kenn

    2014-01-01

    technological advances in microfluidics and reporter genes have improved this scenario. Here, we summarize recent progress in the field, revealing the ubiquitous bacterial stress alarmone ppGpp as an emerging central regulator of multidrug tolerance and persistence, both in stochastically and environmentally...

  20. Nanoparticle-Stabilized Capsules for the Treatment of Bacterial Biofilms.

    Science.gov (United States)

    Duncan, Bradley; Li, Xiaoning; Landis, Ryan F; Kim, Sung Tae; Gupta, Akash; Wang, Li-Sheng; Ramanathan, Rajesh; Tang, Rui; Boerth, Jeffrey A; Rotello, Vincent M

    2015-08-25

    Bacterial biofilms are widely associated with persistent infections. High resistance to conventional antibiotics and prevalent virulence makes eliminating these bacterial communities challenging therapeutic targets. We describe here the fabrication of a nanoparticle-stabilized capsule with a multicomponent core for the treatment of biofilms. The peppermint oil and cinnamaldehyde combination that comprises the core of the capsules act as potent antimicrobial agents. An in situ reaction at the oil/water interface between the nanoparticles and cinnamaldehyde structurally augments the capsules to efficiently deliver the essential oil payloads, effectively eradicating biofilms of clinically isolated pathogenic bacteria strains. In contrast to their antimicrobial action, the capsules selectively promoted fibroblast proliferation in a mixed bacteria/mammalian cell system making them promising for wound healing applications. PMID:26083534

  1. Cognitive outcome in adults after bacterial meningitis.

    NARCIS (Netherlands)

    Hoogman, M.; Beek, D. van de; Weisfelt, M.; Gans, J. de; Schmand, B.

    2007-01-01

    OBJECTIVE: To evaluate cognitive outcome in adult survivors of bacterial meningitis. METHODS: Data from three prospective multicentre studies were pooled and reanalysed, involving 155 adults surviving bacterial meningitis (79 after pneumococcal and 76 after meningococcal meningitis) and 72 healthy c

  2. Relativistic Guiding Center Equations

    Energy Technology Data Exchange (ETDEWEB)

    White, R. B. [PPPL; Gobbin, M. [Euratom-ENEA Association

    2014-10-01

    In toroidal fusion devices it is relatively easy that electrons achieve relativistic velocities, so to simulate runaway electrons and other high energy phenomena a nonrelativistic guiding center formalism is not sufficient. Relativistic guiding center equations including flute mode time dependent field perturbations are derived. The same variables as used in a previous nonrelativistic guiding center code are adopted, so that a straightforward modifications of those equations can produce a relativistic version.

  3. Chemical Security Analysis Center

    Data.gov (United States)

    Federal Laboratory Consortium — In 2006, by Presidential Directive, DHS established the Chemical Security Analysis Center (CSAC) to identify and assess chemical threats and vulnerabilities in the...

  4. Surgery center joint ventures.

    Science.gov (United States)

    Zasa, R J

    1999-01-01

    Surgery centers have been accepted as a cost effective, patient friendly vehicle for delivery of quality ambulatory care. Hospitals and physician groups also have made them the vehicles for coming together. Surgery centers allow hospitals and physicians to align incentives and share benefits. It is one of the few types of health care businesses physicians can own without anti-fraud and abuse violation. As a result, many surgery center ventures are now jointly owned by hospitals and physician groups. This article outlines common structures that have been used successfully to allow both to own and govern surgery centers.

  5. Electron Microscopy Center (EMC)

    Data.gov (United States)

    Federal Laboratory Consortium — The Electron Microscopy Center (EMC) at Argonne National Laboratory develops and maintains unique capabilities for electron beam characterization and applies those...

  6. Test Control Center (TCC)

    Data.gov (United States)

    Federal Laboratory Consortium — The Test Control Center (TCC) provides a consolidated facility for planning, coordinating, controlling, monitoring, and analyzing distributed test events. ,The TCC...

  7. Center for Deployment Psychology

    Data.gov (United States)

    Federal Laboratory Consortium — The Center for Deployment Psychology was developed to promote the education of psychologists and other behavioral health specialists about issues pertaining to the...

  8. Airline Operation Center Workstation

    Data.gov (United States)

    Department of Transportation — The Airline Operation Center Workstation (AOC Workstation) represents equipment available to users of the National Airspace system, outside of the FAA, that enables...

  9. Environmental Modeling Center

    Data.gov (United States)

    Federal Laboratory Consortium — The Environmental Modeling Center provides the computational tools to perform geostatistical analysis, to model ground water and atmospheric releases for comparison...

  10. Data Center at NICT

    Science.gov (United States)

    Ichikawa, Ryuichi; Sekido, Mamoru

    2013-01-01

    The Data Center at the National Institute of Information and Communications Technology (NICT) archives and releases the databases and analysis results processed at the Correlator and the Analysis Center at NICT. Regular VLBI sessions of the Key Stone Project VLBI Network were the primary objective of the Data Center. These regular sessions continued until the end of November 2001. In addition to the Key Stone Project VLBI sessions, NICT has been conducting geodetic VLBI sessions for various purposes, and these data are also archived and released by the Data Center.

  11. Small Business Development Center

    Data.gov (United States)

    Small Business Administration — Small Business Development Centers (SBDCs) provide assistance to small businesses and aspiring entrepreneurs throughout the United States and its territories. SBDCs...

  12. Filtration properties of bacterial cellulose membranes

    OpenAIRE

    Lehtonen, Janika

    2015-01-01

    Bacterial cellulose has the same molecular formula as cellulose from plant origin, but it is characterized by several unique properties including high purity, crystallinity and mechanical strength. These properties are dependent on parameters such as the bacterial strain used, the cultivation conditions and post-growth processing. The possibility to achieve bacterial cellulose membranes with different properties by varying these parameters could make bacterial cellulose an interesting materi...

  13. Desulfovibrio bacterial species are increased in ulcerative colitis.

    LENUS (Irish Health Repository)

    Rowan, Fiachra

    2012-02-01

    BACKGROUND: Debate persists regarding the role of Desulfovibrio subspecies in ulcerative colitis. Combined microscopic and molecular techniques enable this issue to be investigated by allowing precise enumeration of specific bacterial species within the colonic mucous gel. The aim of this study was to combine laser capture microdissection and quantitative polymerase chain reaction to determine Desulfovibrio copy number in crypt-associated mucous gel in health and in acute and chronic ulcerative colitis. METHODS: Colonic mucosal biopsies were harvested from healthy controls (n = 19) and patients with acute (n = 10) or chronic (n = 10) ulcerative colitis. Crypt-associated mucous gel was obtained by laser capture microdissection throughout the colon. Pan-bacterial 16S rRNA and Desulfovibrio copy number\\/mm were obtained by polymerase chain reaction at each locus. Bacterial copy numbers were interrogated for correlation with location and disease activity. Data were evaluated using a combination of ordinary linear methods and linear mixed-effects models to cater for multiple interactions. RESULTS: Desulfovibrio positivity was significantly increased in acute and chronic ulcerative colitis at multiple levels within the colon, and after normalization with total bacterial signal, the relative Desulfovibrio load was increased in acute colitis compared with controls. Desulfovibrio counts did not significantly correlate with age, disease duration, or disease activity but interlevel correlations were found in adjacent colonic segments in the healthy control and chronic ulcerative colitis groups. CONCLUSION: The presence of Desulfovibrio subspecies is increased in ulcerative colitis and the data presented suggest that these bacteria represent an increased percentage of the colonic microbiome in acute ulcerative colitis.

  14. Starting a pharmacovigilance center: Actions for implementation

    Directory of Open Access Journals (Sweden)

    Mrinmoy Chakrabarty

    2011-01-01

    Full Text Available With burgeoning reports of adverse drug reactions due to pharmacotherapy, pharmacovigilance (PV is the buzz word in health care circles. While there are experts in this rapidly expanding field, there are many health care professionals who do not fully appreciate the import of PV in the context of modern therapeutics. In view of the national directive to institutionalize a PV center in every medical college of India, there is an urgent need to inform, educate, and enlighten the readers about the constitution and dynamics of a PV center, which this article attempts to fulfill.

  15. Purifying Plasmid DNA from Bacterial Colonies Using the Qiagen Miniprep Kit

    OpenAIRE

    Zhang, Shenyuan; Cahalan, Michael D.

    2007-01-01

    Plasmid DNA purification from E. coli is a core technique for molecular cloning. Small scale purification (miniprep) from less than 5 ml of bacterial culture is a quick way for clone verification or DNA isolation, followed by further enzymatic reactions (polymerase chain reaction and restriction enzyme digestion). Here, we video-recorded the general procedures of miniprep through the QIAGEN's QIAprep 8 Miniprep Kit, aiming to introducing this highly efficient technique to the general beginner...

  16. Distribution of Triplet Separators in Bacterial Genomes

    Institute of Scientific and Technical Information of China (English)

    HU Rui; ZHENG Wei-Mou

    2001-01-01

    Distributions of triplet separator lengths for two bacterial complete genomes are analyzed. The theoretical distributions for the independent random sequence and the first-order Markov chain are derived and compared with the distributions of the bacterial genomes. A prominent double band structure, which does not exist in the theoretical distributions, is observed in the bacterial distributions for most triplets.``

  17. Funding Opportunity: Genomic Data Centers

    Science.gov (United States)

    Funding Opportunity CCG, Funding Opportunity Center for Cancer Genomics, CCG, Center for Cancer Genomics, CCG RFA, Center for cancer genomics rfa, genomic data analysis network, genomic data analysis network centers,

  18. Microfluidic chemical reaction circuits

    Science.gov (United States)

    Lee, Chung-cheng; Sui, Guodong; Elizarov, Arkadij; Kolb, Hartmuth C.; Huang, Jiang; Heath, James R.; Phelps, Michael E.; Quake, Stephen R.; Tseng, Hsian-rong; Wyatt, Paul; Daridon, Antoine

    2012-06-26

    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  19. Common Reactions After Trauma

    Science.gov (United States)

    ... here Enter ZIP code here Common Reactions After Trauma Public This section is for Veterans, General Public, Family, & Friends Common Reactions After Trauma Available in Spanish: Reacciones Comunes Después de un ...

  20. Anaphylaxis-Like Reactions

    Science.gov (United States)

    ... be "primed" by previous exposure to cause anaphylaxis, anaphylactoid reactions can occur with no previous exposure at all. ... an X-ray. Although the mechanism of an anaphylactoid reaction is different, the treatment is the same as ...

  1. Microscale Thermite Reactions.

    Science.gov (United States)

    Arnaiz, Francisco J.; Aguado, Rafael; Arnaiz, Susana

    1998-01-01

    Describes the adaptation of thermite (aluminum with metal oxides) reactions from whole-class demonstrations to student-run micro-reactions. Lists detailed directions and possible variations of the experiment. (WRM)

  2. Preequilibrium Nuclear Reactions

    International Nuclear Information System (INIS)

    After a survey on existing experimental data on precompound reactions and a description of preequilibrium reactions, theoretical models and quantum mechanical theories of preequilibrium emission are presented. The 25 papers of this meeting are analyzed separately

  3. Double Pion Production Reactions

    CERN Document Server

    Oset, E; Cano, F; Hernández, E; Kamalov, S S; Nacher, J C; Tejedor, J A G

    1999-01-01

    We report on reactions producing two pions induced by real and virtual photons or nucleons. The role of different resonances in these reactions is emphasized. Novel results on coherent two pion photoproduction in nuclei are also reported.

  4. Use of portable electronic devices in a hospital setting and their potential for bacterial colonization.

    Science.gov (United States)

    Khan, Amber; Rao, Amitha; Reyes-Sacin, Carlos; Hayakawa, Kayoko; Szpunar, Susan; Riederer, Kathleen; Kaye, Keith; Fishbain, Joel T; Levine, Diane

    2015-03-01

    Portable electronic devices are increasingly being used in the hospital setting. As with other fomites, these devices represent a potential reservoir for the transmission of pathogens. We conducted a convenience sampling of devices in 2 large medical centers to identify bacterial colonization rates and potential risk factors.

  5. Microarray-based identification of clinically relevant vaginal bacteria in relation to bacterial vaginosis

    NARCIS (Netherlands)

    Dols, J.A.M.; Smit, P.W.; Kort, R.; Reid, G.; Schuren, F.H.J.; Tempelman, H.; Bontekoe, T.R.; Korporaal, H.; Boon, M.E.

    2011-01-01

    Objective: The objective was to examine the use of a tailor-made DNA microarray containing probes representing the vaginal microbiota to examine bacterial vaginosis. Study Design: One hundred one women attending a health center for HIV testing in South Africa were enrolled. Stained, liquid-based cyt

  6. Chemical transport reactions

    CERN Document Server

    Schäfer, Harald

    2013-01-01

    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and

  7. Bacterial chromosome organization and segregation.

    Science.gov (United States)

    Badrinarayanan, Anjana; Le, Tung B K; Laub, Michael T

    2015-01-01

    If fully stretched out, a typical bacterial chromosome would be nearly 1 mm long, approximately 1,000 times the length of a cell. Not only must cells massively compact their genetic material, but they must also organize their DNA in a manner that is compatible with a range of cellular processes, including DNA replication, DNA repair, homologous recombination, and horizontal gene transfer. Recent work, driven in part by technological advances, has begun to reveal the general principles of chromosome organization in bacteria. Here, drawing on studies of many different organisms, we review the emerging picture of how bacterial chromosomes are structured at multiple length scales, highlighting the functions of various DNA-binding proteins and the impact of physical forces. Additionally, we discuss the spatial dynamics of chromosomes, particularly during their segregation to daughter cells. Although there has been tremendous progress, we also highlight gaps that remain in understanding chromosome organization and segregation. PMID:26566111

  8. Bacterial streamers in curved microchannels

    Science.gov (United States)

    Rusconi, Roberto; Lecuyer, Sigolene; Guglielmini, Laura; Stone, Howard

    2009-11-01

    Biofilms, generally identified as microbial communities embedded in a self-produced matrix of extracellular polymeric substances, are involved in a wide variety of health-related problems ranging from implant-associated infections to disease transmissions and dental plaque. The usual picture of these bacterial films is that they grow and develop on surfaces. However, suspended biofilm structures, or streamers, have been found in natural environments (e.g., rivers, acid mines, hydrothermal hot springs) and are always suggested to stem from a turbulent flow. We report the formation of bacterial streamers in curved microfluidic channels. By using confocal laser microscopy we are able to directly image and characterize the spatial and temporal evolution of these filamentous structures. Such streamers, which always connect the inner corners of opposite sides of the channel, are always located in the middle plane. Numerical simulations of the flow provide evidences for an underlying hydrodynamic mechanism behind the formation of the streamers.

  9. Bacterial survival in Martian conditions

    CERN Document Server

    D'Alessandro, Giuseppe Galletta; Giulio Bertoloni; Maurizio

    2010-01-01

    We shortly discuss the observable consequences of the two hypotheses about the origin of life on Earth and Mars: the Lithopanspermia (Mars to Earth or viceversa) and the origin from a unique progenitor, that for Earth is called LUCA (the LUCA hypothesis). To test the possibility that some lifeforms similar to the terrestrial ones may survive on Mars, we designed and built two simulators of Martian environments where to perform experiments with different bacterial strains: LISA and mini-LISA. Our LISA environmental chambers can reproduce the conditions of many Martian locations near the surface trough changes of temperature, pressure, UV fluence and atmospheric composition. Both simulators are open to collaboration with other laboratories interested in performing experiments on many kind of samples (biological, minerals, electronic) in situations similar to that of the red planet. Inside LISA we have studied the survival of several bacterial strains and endospores. We verified that the UV light is the major re...

  10. Collective Functionality through Bacterial Individuality

    Science.gov (United States)

    Ackermann, Martin

    According to the conventional view, the properties of an organism are a product of nature and nurture - of its genes and the environment it lives in. Recent experiments with unicellular organisms have challenged this view: several molecular mechanisms generate phenotypic variation independently of environmental signals, leading to variation in clonal groups. My presentation will focus on the causes and consequences of this microbial individuality. Using examples from bacterial genetic model systems, I will first discuss different molecular and cellular mechanisms that give rise to bacterial individuality. Then, I will discuss the consequences of individuality, and focus on how phenotypic variation in clonal populations of bacteria can promote interactions between individuals, lead to the division of labor, and allow clonal groups of bacteria to cope with environmental uncertainty. Variation between individuals thus provides clonal groups with collective functionality.

  11. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Consumers Businesses Contact CPSC Website Design Feedback Consumers: Español Businesses: Español , 中文 , Tiếng Việt Connect with Us : Twitter YouTube ... Safely Home / Safety Education / Safety Education Centers En Español Carbon Monoxide Information Center The Invisible Killer Carbon ...

  12. Technology Information Center

    International Nuclear Information System (INIS)

    A Transportation Technology Center (TTC) has been established at Sandia to address the transportation of nuclear waste and spent fuel. The Technology Information Center (TIC) acts as TTC's clearing house for nuclear material transportation information. TIC's activities are divided into three activities: public information, policy information, and technical information. Some of the uses of TIC's activities are briefly outlined

  13. Center for Women Veterans

    Science.gov (United States)

    ... VA » Center for Women Veterans (CWV) Center for Women Veterans (CWV) 10/27/2016 #VeteranOfTheDay Army Veteran ... Meet the Veteran of the Day » Employment and Women Veterans An interview with the Women Veteran Program ...

  14. Call Center Capacity Planning

    DEFF Research Database (Denmark)

    Nielsen, Thomas Bang

    The main topics of the thesis are theoretical and applied queueing theory within a call center setting. Call centers have in recent years become the main means of communication between customers and companies, and between citizens and public institutions. The extensively computerized infrastructu...

  15. NASA propagation information center

    Science.gov (United States)

    Smith, Ernest K.; Flock, Warren L.

    1990-07-01

    The NASA Propagation Information Center became formally operational in July 1988. It is located in the Department of Electrical and Computer Engineering of the University of Colorado at Boulder. The center is several things: a communications medium for the propagation with the outside world, a mechanism for internal communication within the program, and an aid to management.

  16. Simple Machine Science Centers

    Science.gov (United States)

    Chessin, Debby

    2007-01-01

    Science centers can engage students; accommodate different learning styles and individual interests; help students become independent and confident learners; and encourage social skills among students. In this article, the author worked with third-grade students as they completed activities at learning centers during a week-long unit on simple…

  17. Bacterial communication and group behavior

    OpenAIRE

    Greenberg, E. Peter

    2003-01-01

    The existence of species-specific and interspecies bacterial cell-cell communication and group organization was only recently accepted. Researchers are now realizing that the ability of these microbial teams to communicate and form structures, known as biofilms, at key times during the establishment of infection significantly increases their ability to evade both host defenses and antibiotics. This Perspective series discusses the known signaling mechanisms, the roles they play in both chroni...

  18. The problem of bacterial diarrhoea.

    Science.gov (United States)

    Harries, J T

    1976-01-01

    The reported incidence of "pathogenic" bacteria, as judged by serotype, in the stools of children with acute diarrhoea has varied from 4 to 33% over the last twenty years. Techniques such as tissue culture provide a means for detecting enterotoxin-producing strains of bacteria, strains which often do not possess "pathogenic" serotypes. "Pathogenicity" requires redefinition, and the aetiological importance of bacteria in diarrhoea is probably considerably greater than previous reports have indicated. Colonization of the bowel by a pathogen will result in structural and/or mucosal abnormalities, and will depend on a series of complex interactions between the external environment, the pathogen, and the host and its resident bacterial flora. Enteropathogenic bacteria may be broadly classified as (i) invasive (e.g. Shigella, Salmonella and some Escherichia coli) which predominantly affect the distal bowel, or (ii) non-invasive (e.g. Vibrio cholerae and E. coli) which affect the proximal bowel. V. cholerae and E. coli elaborate heat-labile enterotoxins which activate adenylate cyclase and induce small intestinal secretion; the secretory effects of heat-stable E. coli and heat-labile Shigella dysenteriae enterotoxins are not accompanied by cyclase activation. The two major complications of acute diarrhoea are (i) hypernatraemic dehydration with its attendant neurological, renal and vascular lesions, and (ii) protracted diarrhoea which may lead to severe malnutrition. Deconjugation of bile salts and colonization of the small bowel with toxigenic strains of E. coli may be important in the pathophysiology of the protracted diarrhoea syndrome. The control of bacterial diarrhoea requires a corrdinated political, educational, social, public health and scientific attack. Bacterial diarrhoea is a major health problem throughout the world, and carries an appreciable morbidity and mortality. This is particularly the case during infancy, and in those developing parts of the world

  19. Bacterial survival in Martian conditions

    OpenAIRE

    Galletta, Giuseppe; Bertoloni, Giulio; D'Alessandro, Maurizio

    2010-01-01

    We shortly discuss the observable consequences of the two hypotheses about the origin of life on Earth and Mars: the Lithopanspermia (Mars to Earth or viceversa) and the origin from a unique progenitor, that for Earth is called LUCA (the LUCA hypothesis). To test the possibility that some lifeforms similar to the terrestrial ones may survive on Mars, we designed and built two simulators of Martian environments where to perform experiments with different bacterial strains: LISA and mini-LISA. ...

  20. Small intestinal bacterial overgrowth syndrome

    Institute of Scientific and Technical Information of China (English)

    Jan; Bures; Jiri; Cyrany; Darina; Kohoutova; Miroslav; Frstl; Stanislav; Rejchrt; Jaroslav; Kvetina; Viktor; Vorisek; Marcela; Kopacova

    2010-01-01

    Human intestinal microbiota create a complex polymi-crobial ecology. This is characterised by its high population density, wide diversity and complexity of interaction. Any dysbalance of this complex intestinal microbiome, both qualitative and quantitative, might have serious health consequence for a macro-organism, including small intestinal bacterial overgrowth syndrome (SIBO).SIBO is defined as an increase in the number and/or alteration in the type of bacteria in the upper gastro-intestinal tract. There...

  1. Population dynamics of bacterial persistence

    OpenAIRE

    Patra, Pintu

    2014-01-01

    The life of microorganisms is characterized by two main tasks, rapid growth under conditions permitting growth and survival under stressful conditions. The environments, in which microorganisms dwell, vary in space and time. The microorganisms innovate diverse strategies to readily adapt to the regularly fluctuating environments. Phenotypic heterogeneity is one such strategy, where an isogenic population splits into subpopulations that respond differently under identical environments. Bacteri...

  2. Immunization by a bacterial aerosol

    OpenAIRE

    Garcia-Contreras, Lucila; Wong, Yun-Ling; Muttil, Pavan; Padilla, Danielle; Sadoff, Jerry; DeRousse, Jessica; Germishuizen, Willem Andreas; Goonesekera, Sunali; Elbert, Katharina; Bloom, Barry R.; Miller, Rich; Fourie, P. Bernard; Hickey, Anthony; Edwards, David

    2008-01-01

    By manufacturing a single-particle system in two particulate forms (i.e., micrometer size and nanometer size), we have designed a bacterial vaccine form that exhibits improved efficacy of immunization. Microstructural properties are adapted to alter dispersive and aerosol properties independently. Dried “nanomicroparticle” vaccines possess two axes of nanoscale dimensions and a third axis of micrometer dimension; the last one permits effective micrometer-like physical dispersion, and the form...

  3. Rheumatoid arthritis and bacterial infections

    OpenAIRE

    N L Prokopjeva; N N Vesikova; I M Marusenko; V A Ryabkov

    2008-01-01

    To study features of bacterial infections course in pts with rheumatoid arthritis (RA) and changes of laboratory measures after focus of infection sanation. Material and methods. 46 pts with definite rheumatoid arthritis were examined at the time of comorbid infection (Cl) detection and after infection focus sanation. Bacteriological test with evaluation of flora sensitivity to antibiotics by disco-diffusion method was performed at baseline and after the course of antibacterial therapy to ass...

  4. Molecular approaches for bacterial azoreductases

    OpenAIRE

    Montira Leelakriangsak

    2013-01-01

    Azo dyes are the dominant types of synthetic dyes, widely used in textiles, foods, leather, printing, tattooing, cosmetics, and pharmaceutical industries. Many microorganisms are able to decolorize azo dyes, and there is increasing interest in biological waste treatment methods. Bacterial azoreductases can cleave azo linkages (-N=N-) in azo dyes, forming aromatic amines. This review mainly focuses on employing molecular approaches, including gene manipulation and recombinant strains, to study...

  5. Bacterial meningitis by streptococcus agalactiae

    OpenAIRE

    Villarreal-Velásquez Tatiana Paola; Cortés-Daza César Camilo

    2012-01-01

    Introduction: bacterial meningitis is an infectious disease considered a medicalemergency. The timely management has an important impact on the evolution of thedisease. Streptococcus agalactiae, a major causative agent of severe infections innewborns can colonize different tissues, including the central nervous system.Case report: Male patient 47 years old from rural areas, with work activity as amilker of cattle, referred to tertiary care, with disorientation, neck stiffness, and grandmal se...

  6. Anaphylactoid reactions to paracetamol

    OpenAIRE

    Ayonrinde, O.; Saker, B.

    2000-01-01

    The toxic effects of paracetamol in overdose quantities are well recognised but the occurrence of anaphylactoid reactions to paracetamol is infrequently identified by consumers and health care professionals. Nevertheless adverse reactions to this drug, even in therapeutic doses, can have fatal or near fatal consequences. A case of an anaphylactoid reaction to paracetamol is described.


Keywords: paracetamol; anaphylaxis; allergy; hypersensitivity

  7. The Role of Bacterial Spores in Metal Cycling and Their Potential Application in Metal Contaminant Bioremediation.

    Science.gov (United States)

    Butterfield, Cristina N; Lee, Sung-Woo; Tebo, Bradley M

    2016-04-01

    Bacteria are one of the premier biological forces that, in combination with chemical and physical forces, drive metal availability in the environment. Bacterial spores, when found in the environment, are often considered to be dormant and metabolically inactive, in a resting state waiting for favorable conditions for them to germinate. However, this is a highly oversimplified view of spores in the environment. The surface of bacterial spores represents a potential site for chemical reactions to occur. Additionally, proteins in the outer layers (spore coats or exosporium) may also have more specific catalytic activity. As a consequence, bacterial spores can play a role in geochemical processes and may indeed find uses in various biotechnological applications. The aim of this review is to introduce the role of bacteria and bacterial spores in biogeochemical cycles and their potential use as toxic metal bioremediation agents. PMID:27227313

  8. Characterization of novel thermostable bacterial Laccase-like multi-copper oxidases

    DEFF Research Database (Denmark)

    Brander, Søren; Mikkelsen, Jørn Dalgaard

    and thermostability. Bacillus clausii KSM-16 is known to produce a potent alkalophilic and thermostable protease that is sometimes used in laundry detergent mixes. We have expressed and characterized the LMCO coded in the genome of the same bacterial strain, and found that it is a thermostable enzyme with substrate...... in nature is not well understood. If we want to change a LMCO, to specifically catalyze a man-made reaction, it becomes important to have a diverse and stable starting protein. In this regard bacterial LMCOs are of special interest, because they are intrinsically thermostable and distinct variants can...... be found in the rapidly increasing number of sequenced bacterial genomes. This dissertation describes our effort to identify and express novel LMCOs from bacterial origins. Some of these enzymes were also characterized, and special emphasis was put on revealing their substrate specificity...

  9. Relative Lyapunov Center Bifurcations

    DEFF Research Database (Denmark)

    Wulff, Claudia; Schilder, Frank

    2014-01-01

    Relative equilibria (REs) and relative periodic orbits (RPOs) are ubiquitous in symmetric Hamiltonian systems and occur, for example, in celestial mechanics, molecular dynamics, and rigid body motion. REs are equilibria, and RPOs are periodic orbits of the symmetry reduced system. Relative Lyapunov...... center bifurcations are bifurcations of RPOs from REs corresponding to Lyapunov center bifurcations of the symmetry reduced dynamics. In this paper we first prove a relative Lyapunov center theorem by combining recent results on the persistence of RPOs in Hamiltonian systems with a symmetric Lyapunov...... center theorem of Montaldi, Roberts, and Stewart. We then develop numerical methods for the detection of relative Lyapunov center bifurcations along branches of RPOs and for their computation. We apply our methods to Lagrangian REs of the N-body problem....

  10. CD83 Modulates B Cell Activation and Germinal Center Responses.

    Science.gov (United States)

    Krzyzak, Lena; Seitz, Christine; Urbat, Anne; Hutzler, Stefan; Ostalecki, Christian; Gläsner, Joachim; Hiergeist, Andreas; Gessner, André; Winkler, Thomas H; Steinkasserer, Alexander; Nitschke, Lars

    2016-05-01

    CD83 is a maturation marker for dendritic cells. In the B cell lineage, CD83 is expressed especially on activated B cells and on light zone B cells during the germinal center (GC) reaction. The function of CD83 during GC responses is unclear. CD83(-/-) mice have a strong reduction of CD4(+) T cells, which makes it difficult to analyze a functional role of CD83 on B cells during GC responses. Therefore, in the present study we generated a B cell-specific CD83 conditional knockout (CD83 B-cKO) model. CD83 B-cKO B cells show defective upregulation of MHC class II and CD86 expression and impaired proliferation after different stimuli. Analyses of GC responses after immunization with various Ags revealed a characteristic shift in dark zone and light zone B cell numbers, with an increase of B cells in the dark zone of CD83 B-cKO mice. This effect was not accompanied by alterations in the level of IgG immune responses or by major differences in affinity maturation. However, an enhanced IgE response was observed in CD83 B-cKO mice. Additionally, we observed a strong competitive disadvantage of CD83-cKO B cells in GC responses in mixed bone marrow chimeras. Furthermore, infection of mice with Borrelia burgdorferi revealed a defect in bacterial clearance of CD83 B-cKO mice with a shift toward a Th2 response, indicated by a strong increase in IgE titers. Taken together, our results show that CD83 is important for B cell activation and modulates GC composition and IgE Ab responses in vivo. PMID:26983787

  11. Bacterial sex in dental plaque

    Directory of Open Access Journals (Sweden)

    Ingar Olsen

    2013-06-01

    Full Text Available Genes are transferred between bacteria in dental plaque by transduction, conjugation, and transformation. Membrane vesicles can also provide a mechanism for horizontal gene transfer. DNA transfer is considered bacterial sex, but the transfer is not parallel to processes that we associate with sex in higher organisms. Several examples of bacterial gene transfer in the oral cavity are given in this review. How frequently this occurs in dental plaque is not clear, but evidence suggests that it affects a number of the major genera present. It has been estimated that new sequences in genomes established through horizontal gene transfer can constitute up to 30% of bacterial genomes. Gene transfer can be both inter- and intrageneric, and it can also affect transient organisms. The transferred DNA can be integrated or recombined in the recipient's chromosome or remain as an extrachromosomal inheritable element. This can make dental plaque a reservoir for antimicrobial resistance genes. The ability to transfer DNA is important for bacteria, making them better adapted to the harsh environment of the human mouth, and promoting their survival, virulence, and pathogenicity.

  12. Cytochemical Differences in Bacterial Glycocalyx

    Science.gov (United States)

    Krautgartner, Wolf Dietrich; Vitkov, Ljubomir; Hannig, Matthias; Pelz, Klaus; Stoiber, Walter

    2005-02-01

    To examine new cytochemical aspects of the bacterial adhesion, a strain 41452/01 of the oral commensal Streptococcus sanguis and a wild strain of Staphylococcus aureus were grown with and without sucrose supplementation for 6 days. Osmiumtetraoxyde (OsO4), uranyl acetate (UA), ruthenium red (RR), cupromeronic blue (CB) staining with critical electrolytic concentrations (CECs), and the tannic acid-metal salt technique (TAMST) were applied for electron microscopy. Cytochemically, only RR-positive fimbriae in S. sanguis were visualized. By contrast, some types of fimbriae staining were observed in S. aureus glycocalyx: RR-positive, OsO4-positive, tannophilic and CB-positive with ceasing point at 0.3 M MgCl2. The CB staining with CEC, used for the first time for visualization of glycoproteins of bacterial glycocalyx, also reveals intacellular CB-positive substances-probably the monomeric molecules, that is, subunits forming the fimbriae via extracellular assembly. Thus, glycosylated components of the biofilm matrix can be reliably related to single cells. The visualization of intracellular components by CB with CEC enables clear distinction between S. aureus and other bacteria, which do not produce CB-positive substances. The small quantities of tannophilic substances found in S. aureus makes the use of TAMST for the same purpose difficult. The present work protocol enables, for the first time, a partial cytochemical differentiation of the bacterial glycocalyx.

  13. Flare-up reactions in severe drug hypersensitivity: infection or ongoing T-cell hyperresponsiveness

    OpenAIRE

    Jörg-Walther, Lukas Emanuel; Schnyder, Benno; Helbling, Arthur; Helsing, Karin Silvia; Schüller, Alexandra; Wochner, Annette; Pichler, Werner Joseph

    2015-01-01

    "Flare-up" reactions are late manifestations of severe T-cell-mediated drug hypersensitivity reactions. Management is anti-inflammatory treatment and avoiding unnecessary medicines. Symptoms like fever, lymph node swelling, and blood count abnormalities may lead to confusion with bacterial infections. For prompt recognition it is important to keep the differential diagnosis in mind.

  14. Flare-up reactions in severe drug hypersensitivity: infection or ongoing T-cell hyperresponsiveness

    OpenAIRE

    Jörg-Walther, Lukas; Schnyder, Benno; Helbling, Arthur; Helsing, Karin; Schüller, Alexandra; Wochner, Annette; Pichler, Werner

    2015-01-01

    Key Clinical Message “Flare-up” reactions are late manifestations of severe T-cell-mediated drug hypersensitivity reactions. Management is anti-inflammatory treatment and avoiding unnecessary medicines. Symptoms like fever, lymph node swelling, and blood count abnormalities may lead to confusion with bacterial infections. For prompt recognition it is important to keep the differential diagnosis in mind.

  15. Synthesis of antimicrobial cyclodextrins bearing polyarylamino and polyalkylamino groups via click chemistry for bacterial membrane disruption.

    Science.gov (United States)

    Yamamura, Hatsuo; Sugiyama, Yuuki; Murata, Kensuke; Yokoi, Takanori; Kurata, Ryuji; Miyagawa, Atsushi; Sakamoto, Kenji; Komagoe, Keiko; Inoue, Tsuyoshi; Katsu, Takashi

    2014-05-28

    Cyclodextrin derivatives are synthesized as membrane-disrupting agents via a microwave-assisted Huisgen reaction. Their ability to permeabilize bacterial membranes depends on the amino substituents and an appropriate balance of hydrophobicity and hydrophilicity, thus enabling the preparation of derivatives with selective toxicity against bacteria.

  16. [Bacterial identification methods in the microbiology laboratory].

    Science.gov (United States)

    Bou, Germán; Fernández-Olmos, Ana; García, Celia; Sáez-Nieto, Juan Antonio; Valdezate, Sylvia

    2011-10-01

    In order to identify the agent responsible of the infectious process and understanding the pathogenic/pathological implications, clinical course, and to implement an effective antimicrobial therapy, a mainstay in the practice of clinical microbiology is the allocation of species to a microbial isolation. In daily routine practice microbiology laboratory phenotypic techniques are applied to achieve this goal. However, they have some limitations that are seen more clearly for some kinds of microorganism. Molecular methods can circumvent some of these limitations, although its implementation is not universal. This is due to higher costs and the level of expertise required for thei implementation, so molecular methods are often centralized in reference laboratories and centers. Recently, proteomics-based methods made an important breakthrough in the field of diagnostic microbiology and will undoubtedly have a major impact on the future organization of the microbiology services. This paper is a short review of the most noteworthy aspects of the three bacterial identification methods described above used in microbiology laboratories.

  17. Production of extremophilic bacterial cellulase enzymes in aspergillus niger.

    Energy Technology Data Exchange (ETDEWEB)

    Gladden, John Michael

    2013-09-01

    Enzymes can be used to catalyze a myriad of chemical reactions and are a cornerstone in the biotechnology industry. Enzymes have a wide range of uses, ranging from medicine with the production of pharmaceuticals to energy were they are applied to biofuel production. However, it is difficult to produce large quantities of enzymes, especially if they are non-native to the production host. Fortunately, filamentous fungi, such as Aspergillus niger, are broadly used in industry and show great potential for use a heterologous enzyme production hosts. Here, we present work outlining an effort to engineer A. niger to produce thermophilic bacterial cellulases relevant to lignocellulosic biofuel production.

  18. Reaction kinetics of isopropyl palmitate synthesis

    Institute of Scientific and Technical Information of China (English)

    Lili Fu; Yinge Bai; Gaozhi L; Denggao Jiang

    2015-01-01

    In this study, the kinetics of isopropyl palmitate synthesis including the reaction mechanism was studied based on the two-step noncatalytic method. The liquid-phase diffusion effect on the reaction process was eliminated by adjusting the stirring rate. The results showed that the two-step reaction followed a tetrahedral mechanism and conformed to second-order reaction kinetics. Nucleophilic attack on the carbonyl carbon afforded an intermedi-ate, containing a tetrahedral carbon center. The intermediate ultimately decomposed by elimination of the leav-ing group, affording isopropyl palmitate. The experimental data were analyzed at different temperatures by the integral method. The kinetic equations of the each step were deduced, and the activation energy and frequency factor were obtained. Experiments were performed to verify the feasibility of kinetic equations, and the result showed that the kinetic equations were reliable. This study could be very significant to both industrial application and determining the continuous production of isopropyl palmitate.

  19. Metatranscriptomics reveals overall active bacterial composition in caries lesions

    Directory of Open Access Journals (Sweden)

    Aurea Simón-Soro

    2014-10-01

    Full Text Available Background: Identifying the microbial species in caries lesions is instrumental to determine the etiology of dental caries. However, a significant proportion of bacteria in carious lesions have not been cultured, and the use of molecular methods has been limited to DNA-based approaches, which detect both active and inactive or dead microorganisms. Objective: To identify the RNA-based, metabolically active bacterial composition of caries lesions at different stages of disease progression in order to provide a list of potential etiological agents of tooth decay. Design: Non-cavitated enamel caries lesions (n=15 and dentin caries lesions samples (n=12 were collected from 13 individuals. RNA was extracted and cDNA was constructed, which was used to amplify the 16S rRNA gene. The resulting 780 bp polymerase chain reaction products were pyrosequenced using Titanium-plus chemistry, and the sequences obtained were used to determine the bacterial composition. Results: A mean of 4,900 sequences of the 16S rRNA gene with an average read length of 661 bp was obtained per sample, giving a comprehensive view of the active bacterial communities in caries lesions. Estimates of bacterial diversity indicate that the microbiota of cavities is highly complex, each sample containing between 70 and 400 metabolically active species. The composition of these bacterial consortia varied among individuals and between caries lesions of the same individuals. In addition, enamel and dentin lesions had a different bacterial makeup. Lactobacilli were found almost exclusively in dentin cavities. Streptococci accounted for 40% of the total active community in enamel caries, and 20% in dentin caries. However, Streptococcus mutans represented only 0.02–0.73% of the total bacterial community. Conclusions: The data indicate that the etiology of dental caries is tissue dependent and that the disease has a clear polymicrobial origin. The low proportion of mutans streptococci

  20. Reactivity of bromoalkanes in reactions of coordinated molecular decay

    Science.gov (United States)

    Pokidova, T. S.; Denisov, E. T.

    2016-09-01

    The results from experiments on reactions of the coordinated molecular decay of RBr bromoalkanes on olefin and HBr are analyzed using the model of intersecting parabolas (MIP). Kinetic parameters within the MIP are calculated from the experimental data, enabling calculation of the activation energies ( E) and rate constants ( k) of such reactions, based on the enthalphy of the reaction and the MIP algorithms. The factors affecting the E of the RBr decay reaction are established: the enthalphy of the reaction, triplet repulsion, the energy of radical R• stabilization, the presence of a π bond adjacent to the reaction center, and the dipole-dipole interaction of polar groups. The energy spectrum of the partial energies of activation is constructed for the reaction of coordinated molecular decay of RBr, and the E and k of inverse addition reactions are evaluated.

  1. Energy efficient data centers

    Energy Technology Data Exchange (ETDEWEB)

    Tschudi, William; Xu, Tengfang; Sartor, Dale; Koomey, Jon; Nordman, Bruce; Sezgen, Osman

    2004-03-30

    Data Center facilities, prevalent in many industries and institutions are essential to California's economy. Energy intensive data centers are crucial to California's industries, and many other institutions (such as universities) in the state, and they play an important role in the constantly evolving communications industry. To better understand the impact of the energy requirements and energy efficiency improvement potential in these facilities, the California Energy Commission's PIER Industrial Program initiated this project with two primary focus areas: First, to characterize current data center electricity use; and secondly, to develop a research ''roadmap'' defining and prioritizing possible future public interest research and deployment efforts that would improve energy efficiency. Although there are many opinions concerning the energy intensity of data centers and the aggregate effect on California's electrical power systems, there is very little publicly available information. Through this project, actual energy consumption at its end use was measured in a number of data centers. This benchmark data was documented in case study reports, along with site-specific energy efficiency recommendations. Additionally, other data center energy benchmarks were obtained through synergistic projects, prior PG&E studies, and industry contacts. In total, energy benchmarks for sixteen data centers were obtained. For this project, a broad definition of ''data center'' was adopted which included internet hosting, corporate, institutional, governmental, educational and other miscellaneous data centers. Typically these facilities require specialized infrastructure to provide high quality power and cooling for IT equipment. All of these data center types were considered in the development of an estimate of the total power consumption in California. Finally, a research ''roadmap'' was developed

  2. Bacterial adhesion and biofilms on surfaces

    Institute of Scientific and Technical Information of China (English)

    Trevor Roger Garrett; Manmohan Bhakoo; Zhibing Zhang

    2008-01-01

    Bacterial adhesion has become a significant problem in industry and in the domicile,and much research has been done for deeper understanding of the processes involved.A generic biological model of bacterial adhesion and population growth called the bacterial biofilm growth cycle,has been described and modified many times.The biofilm growth cycle encompasses bacterial adhesion at all levels,starting with the initial physical attraction of bacteria to a substrate,and ending with the eventual liberation of cell dusters from the biofilm matrix.When describing bacterial adhesion one is simply describing one or more stages of biofilm development,neglecting the fact that the population may not reach maturity.This article provides an overview of bacterial adhesion.cites examples of how bac-terial adhesion affects industry and summarises methods and instrumentation used to improve our understanding of the adhesive prop-erties of bacteria.

  3. Mechanisms of bacterially catalyzed reductive dehalogenation

    Energy Technology Data Exchange (ETDEWEB)

    Picardal, F.W.

    1992-12-31

    Nine bacteria were tested for the ability to dehalogenate tetrachloromethane (CT), tetrachloroethene (PCE), and 1, 1, 1-trichloroethane (TCA) under anaerobic conditions. Three bacteria were able to reductively dehalogenate CT. Dehalogenation ability was not readily linked to a common metabolism or changes in culture redox potential. None of the bacteria tested were able to dehalogenate PCE or TCA. One of the bacteria capable of dehalogenating CT, Shewanella putrefaciens, was chosen as a model organism to study mechanisms of bacterially catalyzed reductive dehalogenation. The effect of a variety of alternate electron acceptors on CT dehalogenation ability by S. putrefaciens was determined. oxygen and nitrogen oxides were inhibitory but Fe (III), trimethylamine oxide, and fumarate were not. A model of the electron transport chain of S. putrefaciens was developed to explain inhibition patterns. A period of microaerobic growth prior to CT exposure increased the ability of S. putrefaciens to dehalogenate CT. A microaerobic growth period also increased cytochrome concentrations. A relationship between cytochrome content and dehalogenation ability was developed from studies in which cytochrome concentrations in S. putrefaciens were manipulated by changing growth conditions. Stoichiometry studies using {sup 14}C-CT suggested that CT was first reduced to form a trichloromethyl radical. Reduction of the radical to produce chloroform and reaction of the radical with cellular biochemicals explained observed product distributions. Carbon dioxide or other fully dehalogenated products were not found.

  4. User-centered design

    International Nuclear Information System (INIS)

    The simplification philosophy, as an example, that both of EPRI-URD and EUR emphasize is treated mostly for the cost reduction of the nuclear power plants, but not for the simplification of the structure of user's tasks, which is one of the principles of user-centered design. A user-centered design is a philosophy based on the needs and interests of the user, with an emphasis on making products usable and understandable. However, the nuclear power plants offered these days by which the predominant reactor vendors are hardly user-centered but still designer-centered or technology-centered in viewpoint of fulfilling user requirements. The main goal of user-centered design is that user requirements are elicited correctly, reflected properly into the system requirements, and verified thoroughly by the tests. Starting from the user requirements throughout to the final test, each requirement should be traceable. That's why requirement traceability is a key to the user-centered design, and main theme of a requirement management program, which is suggested to be added into EPRI-URD and EUR in the section of Design Process. (author)

  5. Lens auto-centering

    Science.gov (United States)

    Lamontagne, Frédéric; Desnoyers, Nichola; Doucet, Michel; Côté, Patrice; Gauvin, Jonny; Anctil, Geneviève; Tremblay, Mathieu

    2015-09-01

    In a typical optical system, optical elements usually need to be precisely positioned and aligned to perform the correct optical function. This positioning and alignment involves securing the optical element in a holder or mount. Proper centering of an optical element with respect to the holder is a delicate operation that generally requires tight manufacturing tolerances or active alignment, resulting in costly optical assemblies. To optimize optical performance and minimize manufacturing cost, there is a need for a lens mounting method that could relax manufacturing tolerance, reduce assembly time and provide high centering accuracy. This paper presents a patent pending lens mounting method developed at INO that can be compared to the drop-in technique for its simplicity while providing the level of accuracy close to that achievable with techniques using a centering machine (usually innovative auto-centering method is based on the use of geometrical relationship between the lens diameter, the lens radius of curvature and the thread angle of the retaining ring. The autocentering principle and centering test results performed on real optical assemblies are presented. In addition to the low assembly time, high centering accuracy, and environmental robustness, the INO auto-centering method has the advantage of relaxing lens and barrel bore diameter tolerances as well as lens wedge tolerances. The use of this novel lens mounting method significantly reduces manufacturing and assembly costs for high performance optical systems. Large volume productions would especially benefit from this advancement in precision lens mounting, potentially providing a drastic cost reduction.

  6. Fusion engineering design center

    International Nuclear Information System (INIS)

    In the spring of 1985, the Department of Energy (DOE) directed the Design Center to take a lead responsibility in assessing the engineering feasibility of a very compact tokamak experiment with copper coils. Following this assessment, the Design Center studied the Ignitor concept at the request of DOE and arrived at a design configuration. Many features of this configuration have been incorporated into the national baseline conceptual design for a Compact Ignition Tokamak (CIT). The Design Center continued to participate in the mirror program by contributing to the Minimars design effort, a two-year program to develop and describe an attractive tandem mirror reactor concept. The Design Center's principal role is in configuration definition of the candidate concepts. The Design Center continues to lead the engineering activities for the International Tokamak Reactor program. Advanced commercial tokamaks were studied by the Design Center as part of the Tokamak Power Systems Studies project coordinated by the DOE Office of Fusion Energy. The Design Center also provided design integration of the US effort. A cost accounting system that is applicable to all magnetic fusion reactor design studies was developed and applied to different confinement concepts and types of projects. The system provides the structure for development of a fusion cost database and validated cost estimating procedures

  7. STRUCTURE OF WAVE FRONT AND ORGANIZATION CENTER IN EXCITABLE MEDIA

    Institute of Scientific and Technical Information of China (English)

    刘深泉

    2004-01-01

    With help of establishing the moving coordinate on the wave front surface and the perturbation analysis in the boundary layer, the structures of wave front and organization center in excitable media were studied. The eikonal equation of wave front surface and general equation of organization center were obtained. These eikonal equations reveal the wave front surfaces have structures of twisted scroll wave and Mobius band, the organization centers have structures of knotted and linked ring. These theoretical results not only explain the wave patterns of BZ ( Belousov-Zhabotinskii ) chemical reaction but also give several possibility structures of wave front surface and organization center in general excitable media.

  8. Intramolecular energy transfer reactions in polymetallic

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, J.

    1990-11-01

    This report is concerned with intramolecular, energy-transfer reactions. The concept of preparing synthetically a complex molecular species, capable of absorbing a photon at one metal center (antenna fragment), transferring that energy to a second metal center (reactive fragment) via a bridging ligand was first reported by our group in 1979. It is now apparent that a major emphasis in inorganic chemistry in the future will involve these types of molecular ensembles. Complexes discussed include Rh, Ru, and Cu complexes. 23 refs., 14 tabs.

  9. Reliability Centered Maintenance - Methodologies

    Science.gov (United States)

    Kammerer, Catherine C.

    2009-01-01

    Journal article about Reliability Centered Maintenance (RCM) methodologies used by United Space Alliance, LLC (USA) in support of the Space Shuttle Program at Kennedy Space Center. The USA Reliability Centered Maintenance program differs from traditional RCM programs because various methodologies are utilized to take advantage of their respective strengths for each application. Based on operational experience, USA has customized the traditional RCM methodology into a streamlined lean logic path and has implemented the use of statistical tools to drive the process. USA RCM has integrated many of the L6S tools into both RCM methodologies. The tools utilized in the Measure, Analyze, and Improve phases of a Lean Six Sigma project lend themselves to application in the RCM process. All USA RCM methodologies meet the requirements defined in SAE JA 1011, Evaluation Criteria for Reliability-Centered Maintenance (RCM) Processes. The proposed article explores these methodologies.

  10. National Farm Medicine Center

    Science.gov (United States)

    Research Areas Applied Sciences Biomedical Informatics Clinical Research Epidemiology Farm Medicine Human Genetics Oral-Systemic Health Clinical ... Consulting Agritourism Farm MAPPER Lyme Disease ROPS Rebate Zika Virus National Farm Medicine Center The National Farm ...

  11. Cooperative Tagging Center (CTC)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Cooperative Tagging Center (CTC) began as the Cooperative Game Fish Tagging Program (GTP) at Woods Hole Oceanographic Institute (WHOI) in 1954. The GTP was...

  12. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Chairman Commissioners Contact Information Agency Reports Legislative Affairs Job Opportunities Inspector General Safety Guides Safety Education Centers OnSafety Blog Neighborhood Safety Network Community Outreach ...

  13. FEMA Disaster Recovery Centers

    Data.gov (United States)

    Department of Homeland Security — This is a search site for FEMA's Disaster Recovery Centers (DRC). A DRC is a readily accessible facility or mobile office set up by FEMA where applicants may go for...

  14. Health Center Controlled Network

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Health Center Controlled Network (HCCN) tool is a locator tool designed to make data and information concerning HCCN resources more easily available to our...

  15. Centering in Japanese Discourse

    CERN Document Server

    Walker, M; Côté, S; Walker, Marilyn; Iida, Masayo; Cote, Sharon

    1996-01-01

    In this paper we propose a computational treatment of the resolution of zero pronouns in Japanese discourse, using an adaptation of the centering algorithm. We are able to factor language-specific dependencies into one parameter of the centering algorithm. Previous analyses have stipulated that a zero pronoun and its cospecifier must share a grammatical function property such as {\\sc Subject} or {\\sc NonSubject}. We show that this property-sharing stipulation is unneeded. In addition we propose the notion of {\\sc topic ambiguity} within the centering framework, which predicts some ambiguities that occur in Japanese discourse. This analysis has implications for the design of language-independent discourse modules for Natural Language systems. The centering algorithm has been implemented in an HPSG Natural Language system with both English and Japanese grammars.

  16. HUD Homeownership Centers

    Data.gov (United States)

    Department of Housing and Urban Development — HUD Homeownership Centers (HOCs) insure single family Federal Housing Administration (FHA) mortgages and oversee the selling of HUD homes. FHA has four...

  17. Accredited Birth Centers

    Science.gov (United States)

    ... 717-933-9743 Accredited since January 2016 100 Bright Eyes Midwifery and Wild Rivers Women's Health Accredited ... Birthing Center-Cedar Park Accredited 1130 Cottonwood Creek Trail Building D Suite 2 Cedar Park, TX 78613 ...

  18. ADVANCED DATA CENTER ECONOMY

    OpenAIRE

    Sukhov, R.; Amzarakov, M.; Isaev, E.

    2013-01-01

    The article addresses basic Data Centers (DC) drivers of price and engineering, which specify rules and price evaluation for creation and further operation. DC energy efficiency concept, its influence on DC initial price, operation costs and Total Cost of Ownership.

  19. National Automotive Center - NAC

    Data.gov (United States)

    Federal Laboratory Consortium — Encouraged by the advantages of collaboration, the U.S. Army Tank Automotive Research, Development and Engineering Center (TARDEC) worked with the Secretary of the...

  20. World Trade Center

    Index Scriptorium Estoniae

    2006-01-01

    Esilinastus katastroofifilm "World Trade Center" : stsenarist Andrea Berloff : režissöör Oliver Stone : kunstnik Jan Roelfs : osades Nicholas Cage, Michael Pena, Stephen Dorff jpt : Ameerika Ühendriigid 2006. Ka filmi prototüüpidest

  1. Center for Contaminated Sediments

    Data.gov (United States)

    Federal Laboratory Consortium — The U.S. Army Corps of Engineers Center for Contaminated Sediments serves as a clearinghouse for technology and expertise concerned with contaminated sediments. The...

  2. USU Patient Simulation Center

    Data.gov (United States)

    Federal Laboratory Consortium — he National Capital Area (NCA) Medical Simulation Center is a state-of-the-art training facility located near the main USU campus. It uses simulated patients (i.e.,...

  3. Center Innovation Fund Program

    Data.gov (United States)

    National Aeronautics and Space Administration — To stimulate and encourage creativity and innovation within the NASA Centers. The activities are envisioned to fall within the scope of NASA Space Technology or...

  4. Hazardous Waste Research Center

    Data.gov (United States)

    Federal Laboratory Consortium — A full-service research and evaluation center equipped with safety equipment, a high-bay pilot studies area, and a large-scale pilot studies facility The U.S. Army...

  5. Advanced Missile Signature Center

    Data.gov (United States)

    Federal Laboratory Consortium — The Advanced Missile Signature Center (AMSC) is a national facility supporting the Missile Defense Agency (MDA) and other DoD programs and customers with analysis,...

  6. CNPC International Research Center

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ CNPC International Research Center (CNPCIRC), jointly managed by CNODC and RIPED of China National Petroleum Corporation (CNPC), was established in 1999 for providing technical research support to all the overseas oil and gas projects of CNPC.

  7. The Galactic Center

    OpenAIRE

    R. Genzel; Karas, V.

    2007-01-01

    In the past decade high resolution measurements in the infrared employing adaptive optics imaging on 10m telescopes have allowed determining the three dimensional orbits stars within ten light hours of the compact radio source at the center of the Milky Way. These observations show the presence of a three million solar mass black hole in Sagittarius A* beyond any reasonable doubt. The Galactic Center thus constitutes the best astrophysical evidence for the existence of black holes which have ...

  8. Oil Reserve Center Established

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Like other countries,China has started to grow its strategic oil reserve in case oil supplies are cut On December 18,2007,the National Development and Reform Commission(NDRC),China’s top economic planner,announced that the national oil reserve center has been officially launched.The supervisory system over the oil reserves has three levels: the energy department of the NDRC,the oil reserve center,and the reserve bases.

  9. A mathematical model for the germinal center morphology and affinity maturation

    CERN Document Server

    Meyer-Hermann, M

    2002-01-01

    During germinal center reactions the appearance of two specific zones is observed: the dark and the light zone. Up to now, the origin and function of these zones are poorly understood. In the framework of a stochastic and discrete model several possible pathways of zone development during germinal center reactions are investigated. The importance of the zones in the germinal center for affinity maturation, i.e. the process of antibody optimization is discussed.

  10. Ability of chitosan gels to disrupt bacterial biofilms and their applications in the treatment of bacterial vaginosis.

    Science.gov (United States)

    Kandimalla, Karunya K; Borden, Emma; Omtri, Rajesh S; Boyapati, Siva Prasad; Smith, Michael; Lebby, Kimberly; Mulpuru, Maanavi; Gadde, Mounika

    2013-07-01

    Recurrence of bacterial vaginosis is attributed to the inability of various formulations to disrupt bacterial biofilms. A negatively charged polysaccharide matrix coats the bacterial communities in the biofilm and restricts the penetration of antibiotics. Therefore, bacteria in the deeper segments of the biofilm persist and perpetuate the infection. In this study, we have tested the efficacy of two bioadhesive polymers, cationic chitosan and anionic polycarbophil, to disrupt Pseudomonas aeruginosa biofilms grown in the Center for Disease Control bioreactor as well as on the 96-well plates. The biofilms were treated with various concentrations of polycarbophil and chitosan at pH 4 or 6. Biofilm integrity following various treatments was evaluated by crystal violet stain and laser confocal microscopy employing Syto9 (live-cell stain) and propidium iodide (dead-cell stain). These studies demonstrated that chitosan gel disrupts the P. aeruginosa biofilm more effectively than does polycarbophil; and this effect is independent of the pH and charge densities on either polymers.

  11. Cosmetic tattoo pigment reaction

    OpenAIRE

    Greywal, Tanya; Cohen, Philip R

    2016-01-01

    BackgroundCutaneous reactions to tattoos are most commonly granulomatous or lichenoid. PurposeWe describe a woman who developed a lymphocytic reaction following a cosmetic tattoo procedure with black dye. The reaction occurred not only at the site of the tattoos (eyebrows and eyelash lines), but also in non-tattooed skin (bilateral malar cheeks). Methods and MaterialsWe reviewed PubMed for the following terms: cosmetic, dye, granuloma, granulomatous, lichenoid, lymphocytic, ...

  12. Anaphylactic reactions to cinoxacin.

    OpenAIRE

    Stricker, B H; Slagboom, G.; Demaeseneer, R.; Slootmaekers, V.; Thijs, I.; Olsson, S

    1988-01-01

    During 1981 to mid-1988 three cases of anaphylactic shock after treatment with the quinolone derivative cinoxacin were reviewed by the Netherlands Centre for Monitoring of Adverse Reactions to Drugs and 17 cases of an anaphylactic type of reaction notified to the World Health Organisation Collaborating Centre for International Drug Monitoring. In five out of six patients for whom data were available the reaction began shortly after taking a single capsule of a second or next course of treatme...

  13. Reaction kinetics of polybutylene terephthalate polycondensation reaction

    NARCIS (Netherlands)

    Darda, P. J.; Hogendoorn, J. A.; Versteeg, G. F.; Souren, F.

    2005-01-01

    The kinetics of the forward polycondensation reaction of polybutylene terephthalate (PBT) has been investigated using thermogravimetric analysis (TGA). PBT - prepolymer with an initial degree of polymerization of 5.5 was used as starting material. The PBT prepolymer was prepared from dimethyl tereph

  14. Reactions at Solid Surfaces

    CERN Document Server

    Ertl, Gerhard

    2009-01-01

    Expanding on the ideas first presented in Gerhard Ertl's acclaimed Baker Lectures at Cornell University, Reactions at Solid Surfaces comprises an authoritative, self-contained, book-length introduction to surface reactions for both professional chemists and students alike. Outlining our present understanding of the fundamental processes underlying reactions at solid surfaces, the book provides the reader with a complete view of how chemistry works at surfaces, and how to understand and probe the dynamics of surface reactions. Comparing traditional surface probes with more modern ones, and brin

  15. Desosamine in multicomponent reactions

    NARCIS (Netherlands)

    Achatz, Sepp; Dömling, Alexander

    2006-01-01

    Desosamine occurring ubiquitously in natural products is introduced into isocyanide based multicomponent reaction chemistry. Corresponding products are of potential interest for the design of novel antibiotics. © 2006.

  16. Exchange of rotor components in functioning bacterial flagellar motor

    International Nuclear Information System (INIS)

    The bacterial flagellar motor is a rotary motor driven by the electrochemical potential of a coupling ion. The interaction between a rotor and stator units is thought to generate torque. The overall structure of flagellar motor has been thought to be static, however, it was recently proved that stators are exchanged in a rotating motor. Understanding the dynamics of rotor components in functioning motor is important for the clarifying of working mechanism of bacterial flagellar motor. In this study, we focused on the dynamics and the turnover of rotor components in a functioning flagellar motor. Expression systems for GFP-FliN, FliM-GFP, and GFP-FliG were constructed, and each GFP-fusion was functionally incorporated into the flagellar motor. To investigate whether the rotor components are exchanged in a rotating motor, we performed fluorescence recovery after photobleaching experiments using total internal reflection fluorescence microscopy. After photobleaching, in a tethered cell producing GFP-FliN or FliM-GFP, the recovery of fluorescence at the rotational center was observed. However, in a cell producing GFP-FliG, no recovery of fluorescence was observed. The transition phase of fluorescence intensity after full or partially photobleaching allowed the turnover of FliN subunits to be calculated as 0.0007 s-1, meaning that FliN would be exchanged in tens of minutes. These novel findings indicate that a bacterial flagellar motor is not a static structure even in functioning state. This is the first report for the exchange of rotor components in a functioning bacterial flagellar motor.

  17. Periodontal diseases as bacterial infection

    Directory of Open Access Journals (Sweden)

    A. Bascones Martínez

    2005-12-01

    Full Text Available The periodontal disease is conformed by a group of illnesses affecting the gums and dental support structures. They are caused by certain bacteria found in the bacterial plaque. These bacteria are essential to the onset of illness; however, there are predisposing factors in both the host and the microorganisms that will have an effect on the pathogenesis of the illness. Periodontopathogenic bacterial microbiota is needed, but by itself, it is not enough to cause the illness, requiring the presence of a susceptible host. These diseases have been classified as gingivitis, when limited to the gums, and periodontitis, when they spread to deeper tissues. Classification of periodontal disease has varied over the years.The one used in this work was approved at the International Workshop for a Classification of Periodontal Diseases and Conditions, held in 1999. This study is an overview of the different periodontal disease syndromes. Later, the systematic use of antibiotic treatment consisting of amoxicillin, amoxicillinclavulanic acid, and metronidazole as first line coadjuvant treatment of these illnesses will be reviewed.

  18. Bacterial mutagenicity assays: test methods.

    Science.gov (United States)

    Gatehouse, David

    2012-01-01

    The most widely used assays for detecting chemically induced gene mutations are those employing bacteria. The plate incorporation assay using various Salmonella typhimurium LT2 and E. coli WP2 strains is a short-term bacterial reverse mutation assay specifically designed to detect a wide range of chemical substances capable of causing DNA damage leading to gene mutations. The test is used worldwide as an initial screen to determine the mutagenic potential of new chemicals and drugs.The test uses several strains of S. typhimurium which carry different mutations in various genes of the histidine operon, and E. coli which carry the same AT base pair at the critical mutation site within the trpE gene. These mutations act as hot spots for mutagens that cause DNA damage via different mechanisms. When these auxotrophic bacterial strains are grown on a minimal media agar plates containing a trace of the required amino-acid (histidine or tryptophan), only those bacteria that revert to amino-acid independence (His(+) or Tryp(+)) will grow to form visible colonies. The number of spontaneously induced revertant colonies per plate is relatively constant. However, when a mutagen is added to the plate, the number of revertant colonies per plate is increased, usually in a dose-related manner.This chapter provides detailed procedures for performing the test in the presence and absence of a metabolic activation system (S9-mix), including advice on specific assay variations and any technical problems. PMID:22147566

  19. BACTERIAL DESEASES IN SEA FISH

    Directory of Open Access Journals (Sweden)

    Ivančica Strunjak-Perović

    1997-10-01

    Full Text Available With development of the fish culturing in the sea, the interest in their health also increased. The reason for this are diseases or rather mortality that occur in such controlled cultures and cause great economic losses. By growing large quantities of fish in rather small species, natural conditions are changed, so fish is more sensitive and prone to infection agents (viruses, bacteria, parasites. Besides, a large fish density in the cultural process accelerates spreading if the diseases, but also enables a better perception of them. In wild populations sick specimen very quickly become predator’s prey, witch makes it difficult to note any pathological changes in such fish. There are lots of articles on viral, bacterial and parasitic diseases nowdays, but this work deals exclusively with bacterial deseases that occur in the controlled sea cultures (vibriosis, furunculosis, pastherelosis, nocardiosis, mycobaceriosis, edwardsielosis, yersiniosis, deseases caused by bacteria of genera Flexibacter, Pseudomonas, Aeromonas, Streptococus and bacteria nephryithis. Yet, the knowledge of these deseases vary, depending on wether a fish species is being cultured for a longer period of time or is only being introduced in the controlled culture.

  20. Bioinformatic Comparison of Bacterial Secretomes

    Institute of Scientific and Technical Information of China (English)

    Catharine Song; Aseem Kumar; Mazen Saleh

    2009-01-01

    The rapid increasing number of completed bacterial genomes provides a good op-portunity to compare their proteomes. This study was undertaken to specifically compare and contrast their secretomes-the fraction of the proteome with pre-dicted N-terminal signal sequences, both type Ⅰ and type Ⅱ. A total of 176 theoreti-cal bacterial proteomes were examined using the ExProt program. Compared with the Gram-positives, the Gram-negative bacteria were found, on average, to con-tain a larger number of potential Sec-dependent sequences. In the Gram-negative bacteria but not in the others, there was a positive correlation between proteome size and secretome size, while there was no correlation between secretome size and pathogenicity. Within the Gram-negative bacteria, intracellular pathogens were found to have the smallest secretomes. However, the secretomes of certain bacte-ria did not fit into the observed pattern. Specifically, the secretome of Borrelia burgdoferi has an unusually large number of putative lipoproteins, and the signal peptides of mycoplasmas show closer sequence similarity to those of the Gram-negative bacteria. Our analysis also suggests that even for a theoretical minimal genome of 300 open reading frames, a fraction of this gene pool (up to a maximum of 20%) may code for proteins with Sec-dependent signal sequences.

  1. Bacterial Culture of Neonatal Sepsis

    Directory of Open Access Journals (Sweden)

    AH Movahedian

    2006-08-01

    Full Text Available Neonatal bacterial sepsis is one of the major cause of morbidity and mortality in neonates. This retrospective study was performed to determine the incidence of bacterial sepsis with focus on Gram negative organisms in neonates admitted at Beheshti Hospital in Kashan, during a 3-yr period, from September 2002 to September 2005. Blood culture was performed on all neonates with risk factors or signs of suggestive sepsis. Blood samples were cultured using brain heart infusion (BHI broth according to standard method. From the 1680 neonates 36% had positive blood culture for Pseudomans aeruginosa, 20.7% for Coagulase negative Staphylococci, and 17% for Klebsiella spp. Gram-negative organisms accounted for 72.1% of all positive cultures. The overall mortality rate was 19.8% (22 /111 of whom 63.6% (14 /22 were preterm. Pseudomona aeruginosa and Klebsiella spp. showed a high degree of resistance to commonly used antibiotics (ampicillin, gentamicin as well as third generation cephalosporins. Continued local surveillance studies are urged to monitor emerging antimicrobial resistance and to guide interventions to minimize its occurrence.

  2. Immunization by a bacterial aerosol.

    Science.gov (United States)

    Garcia-Contreras, Lucila; Wong, Yun-Ling; Muttil, Pavan; Padilla, Danielle; Sadoff, Jerry; Derousse, Jessica; Germishuizen, Willem Andreas; Goonesekera, Sunali; Elbert, Katharina; Bloom, Barry R; Miller, Rich; Fourie, P Bernard; Hickey, Anthony; Edwards, David

    2008-03-25

    By manufacturing a single-particle system in two particulate forms (i.e., micrometer size and nanometer size), we have designed a bacterial vaccine form that exhibits improved efficacy of immunization. Microstructural properties are adapted to alter dispersive and aerosol properties independently. Dried "nanomicroparticle" vaccines possess two axes of nanoscale dimensions and a third axis of micrometer dimension; the last one permits effective micrometer-like physical dispersion, and the former provides alignment of the principal nanodimension particle axes with the direction of airflow. Particles formed with this combination of nano- and micrometer-scale dimensions possess a greater ability to aerosolize than particles of standard spherical isotropic shape and of similar geometric diameter. Here, we demonstrate effective application of this biomaterial by using the live attenuated tuberculosis vaccine bacille Calmette-Guérin (BCG). Prepared as a spray-dried nanomicroparticle aerosol, BCG vaccine exhibited high-efficiency delivery and peripheral lung targeting capacity from a low-cost and technically simple delivery system. Aerosol delivery of the BCG nanomicroparticle to normal guinea pigs subsequently challenged with virulent Mycobacterium tuberculosis significantly reduced bacterial burden and lung pathology both relative to untreated animals and to control animals immunized with the standard parenteral BCG. PMID:18344320

  3. Remodeling bacterial polysaccharides by metabolic pathway engineering

    OpenAIRE

    Yi, Wen; Liu, Xianwei; Li, Yanhong; Li, Jianjun; Xia, Chengfeng; Zhou, Guangyan; Zhang, Wenpeng; Zhao, Wei; Chen, Xi; Wang, Peng George

    2009-01-01

    Introducing structural modifications into biomolecules represents a powerful approach to dissect their functions and roles in biological processes. Bacterial polysaccharides, despite their rich structural information and essential roles in bacterium-host interactions and bacterial virulence, have largely been unexplored for in vivo structural modifications. In this study, we demonstrate the incorporation of a panel of monosaccharide analogs into bacterial polysaccharides in a highly homogenou...

  4. Effect of aerosolization on subsequent bacterial survival.

    OpenAIRE

    Walter, M V; Marthi, B; Fieland, V P; Ganio, L M

    1990-01-01

    To determine whether aerosolization could impair bacterial survival, Pseudomonas syringae and Erwinia herbicola were aerosolized in a greenhouse, the aerosol was sampled at various distances from the site of release by using all-glass impingers, and bacterial survival was followed in the impingers for 6 h. Bacterial survival subsequent to aerosolization of P. syringae and E. herbicola was not impaired 1 m from the site of release. P. syringae aerosolized at 3 to 15 m from the site of release ...

  5. Drag Reduction of Bacterial Cellulose Suspensions

    OpenAIRE

    Ogata, Satoshi; Numakawa, Tetsuya; Kubo, Takuya

    2010-01-01

    Drag reduction due to bacterial cellulose suspensions with small environmental loading was investigated. Experiments were carried out by measuring the pressure drop in pipe flow. It was found that bacterial cellulose suspensions give rise to drag reduction in the turbulent flow range. We observed a maximum drag reduction ratio of 11% and found that it increased with the concentration of the bacterial cellulose suspension. However, the drag reduction effect decreased in the presence of mechani...

  6. Drag Reduction of Bacterial Cellulose Suspensions

    OpenAIRE

    Satoshi Ogata; Tetsuya Numakawa; Takuya Kubo

    2011-01-01

    Drag reduction due to bacterial cellulose suspensions with small environmental loading was investigated. Experiments were carried out by measuring the pressure drop in pipe flow. It was found that bacterial cellulose suspensions give rise to drag reduction in the turbulent flow range. We observed a maximum drag reduction ratio of 11% and found that it increased with the concentration of the bacterial cellulose suspension. However, the drag reduction effect decreased in the presence of mechani...

  7. Spatial scales of bacterial diversity in cold-water coral reef ecosystems.

    Directory of Open Access Journals (Sweden)

    Sandra Schöttner

    Full Text Available BACKGROUND: Cold-water coral reef ecosystems are recognized as biodiversity hotspots in the deep sea, but insights into their associated bacterial communities are still limited. Deciphering principle patterns of bacterial community variation over multiple spatial scales may however prove critical for a better understanding of factors contributing to cold-water coral reef stability and functioning. METHODOLOGY/PRINCIPAL FINDINGS: Bacterial community structure, as determined by Automated Ribosomal Intergenic Spacer Analysis (ARISA, was investigated with respect to (i microbial habitat type and (ii coral species and color, as well as the three spatial components (iii geomorphologic reef zoning, (iv reef boundary, and (v reef location. Communities revealed fundamental differences between coral-generated (branch surface, mucus and ambient microbial habitats (seawater, sediments. This habitat specificity appeared pivotal for determining bacterial community shifts over all other study levels investigated. Coral-derived surfaces showed species-specific patterns, differing significantly between Lophelia pertusa and Madrepora oculata, but not between L. pertusa color types. Within the reef center, no community distinction corresponded to geomorphologic reef zoning for both coral-generated and ambient microbial habitats. Beyond the reef center, however, bacterial communities varied considerably from local to regional scales, with marked shifts toward the reef periphery as well as between different in- and offshore reef sites, suggesting significant biogeographic imprinting but weak microbe-host specificity. CONCLUSIONS/SIGNIFICANCE: This study presents the first multi-scale survey of bacterial diversity in cold-water coral reefs, spanning a total of five observational levels including three spatial scales. It demonstrates that bacterial communities in cold-water coral reefs are structured by multiple factors acting at different spatial scales, which has

  8. Bacterial biota in reflux esophagitis and Barrett's esophagus

    Institute of Scientific and Technical Information of China (English)

    Zhiheng Pei; Liying Yang; Richard M Peek; Jr Steven M Levine; David T Pride; Martin J Blaser

    2005-01-01

    AIM: To identify the bacterial flora in conditions such as Barrett's esophagus and reflux esophagitis to determine if they are similar to normal esophageal flora.METHODS: Using broad-range 16S rDNA PCR,esophageal biopsies were examined from 24 patients [9with normal esophageal mucosa, 12 with gastroesophageal reflux disease (GERD), and 3 with Barrett's esophagus].Two separate broad-range PCR reactions were performed for each patient, and the resulting products were cloned.In one patient with Barrett's esophagus, g9 PCR clones were analyzed.RESULTS: Two separate clones were recovered from each patient (total = 48), representing 24 different species, with 14 species homologous to known bacteria,5 homologous to unidentified bacteria, and 5 were not homologous (<97% identity) to any known bacterial 16S rDNA sequences. Seventeen species were found in the reflux esophagitis patients, 5 in the Barrett's esophagus patients, and 10 in normal esophagus patients.Further analysis concentrating on a single biopsy from an individual with Barrett's esophagus revealed the presence of 21. distinct bacterial species. Members of four phyla were represented, including Bacteroidetes,Firmicutes, Proteobacteria, and Actinobacteria.Microscopic examination of each biopsy demonstrated bacteria in intimate association with the distal esophageal epithelium, suggesting that the presence of these bacteria is not transitory.CONCLUSION: These findings provide evidence for a complex, residential bacterial population in esophageal reflux-related disorders. While much of this biota is present in the normal esophagus, more detailed comparisons may help identify potential disease associations.

  9. Bacterial successions in the Broiler Gastrointestinal tract

    DEFF Research Database (Denmark)

    Ranjitkar, Samir; Lawley, Blair; Tannock, Gerald;

    2016-01-01

    of crop, gizzard, ileum and ceca in relation to the feeding strategy and age (8, 15, 22, 25, 29 and 36 days). Of the four dietary treatments, bacterial diversity was analyzed for MBF and CKMS-30 by 454-pyrosequencing of 16S rRNA gene. Since there was no significant influence of diets on bacterial...... diversity, data were pooled for downstream analysis. With increasing age, a clear succession of bacterial communities and an increased bacterial diversity was observed. Lactobacillaceae (mainly Lactobacillus) represented most of the Firmicutes at all ages and in all segments of the gut except the ceca...

  10. UCSF Center for HIV Information

    Science.gov (United States)

    ... Program For providers and patients VA National Viral Hepatitis Program For providers and patients TARGET Center Technical assistance tools for the Ryan White Community AETC National Resource Center Education and training for clinicians UCSF-Gladstone Center for ...

  11. The bacterial contamination rate of glucose meter test strips in the hospital setting

    Science.gov (United States)

    Al-Rubeaan, Khalid A.; Saeb, Amr T. M.; AlNaqeb, Dhekra M.; AlQumaidi, Hamed M.; AlMogbel, Turki A.

    2016-01-01

    Objectives: To assess the rate of bacterial contamination of the multi-use vial and single-use packed glucose meter strips, and to identify the type and frequency of various bacterial contamination in different hospital wards. Methods: This prospective observational study was conducted by a team from the Strategic Center for Diabetes Research in 7 general hospitals in the Central region of Saudi Arabia during the period from August to September 2014 to assess the bacterial contamination rate of the unused strips. A total of 10,447 strips were cultured using proper agar media and incubated both aerobically and anaerobically. Results: The total bacterial contamination rate for the multi-use vials glucose strips was 31.7%, while single-use packed strips were not contaminated at all. Ministry of Health hospitals had the highest contamination rates compared with other hospitals. Critical, obstetric, and surgical wards had the highest bacterial isolates number, where most were in the risk group 3 according to the National Institute of Health guidelines. Staphylococcus species were the most common bacteria found. Conclusion: Glucose meter strips should be recognized as a source of bacterial contamination that could be behind serious hospital acquired infections. The hospital infection control team should adopt proper measures to implement protocols for glucose meter cleaning and glucose strips handling. PMID:27570855

  12. Prevalence of bacterial vaginosis and its risk factors in HIV/AIDSpatients with abnormal vaginal discharge

    Institute of Scientific and Technical Information of China (English)

    Samuel Nwadioha; Daniel Egah; Edmond Banwat; Julie Egesie; Ifeanyi Onwuezobe

    2011-01-01

    Objective:To determine the prevalence of bacterial vaginosis in theHIV/AIDS patients of primary health care clinics in Jos Plateau state, Nigeria.Methods: Female genital swabs were collected from primary health care centers, Jos and analyzed by microscopy, culture,etc. in Jos University Teaching Hospital from December2006 to December2007. Data on epidemiologic indices were collected, using structured interviewer-administered questionnaires.Results:The incidence of bacterial vaginosis in the study was 28%(n=196/700). Among theHIV/AIDS group, the bacterial vaginosis incidence was36% (n=126/350), while in the control (non-HIV patients) group, the rate was20% (70/350) with a statistically significant difference at 95 percent confidence level(P<0.05) .HIV/AIDSand non-HIV (control) patients contributed64% (n=126/196) and36%(n=70/196), respectively. The risks to bacterial vaginosis included vaginal douching with disinfectant/detergent constituted(60%), poor use of condom40%, a median age of26years, and a median number of3 sex partners per week.Conclusions: There was a significant statistical difference in prevalence of bacterial vaginosis between theHIV/AIDS group and non-HIV(control) group of patients in the study. Risk behaviors that promote the incidence of bacterial vaginosis should be especially paid attention.

  13. Final Scientific/Technical Report - DE-FG02-06ER64172 - Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center - Subproject to Co-PI Eric E. Roden

    International Nuclear Information System (INIS)

    This report summarizes research conducted in conjunction with a project entitled 'Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center', which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2. Area 2 is a shallow pathway for migration of contaminated groundwater to seeps in the upper reach of Bear Creek at ORNL, mainly through a ca. 1 m thick layer of gravel located 4-5 m below the ground surface. The gravel layer is sandwiched between an overlying layer of disturbed fill material, and 2-3 m of undisturbed shale saprolite derived from the underlying Nolichucky Shale bedrock. The fill was put in place when contaminated soils were excavated and replaced by native saprolite from an uncontaminated area within Bear Creek Valley; the gravel layer was presumably installed prior to addition of the fill in order to provide a stable surface for the operation of heavy machinery. The undisturbed saprolite is highly weathered bedrock that has unconsolidated character but retains much of the bedding and fracture structure of the parent rock (shale with interbedded limestone). Hydrological tracer studies conducted during the Scheibe et al. field

  14. Hydrogen evolution reaction catalyst

    Science.gov (United States)

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

    2016-02-09

    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  15. Degradations and Rearrangement Reactions

    Science.gov (United States)

    Zhang, Jianbo

    This section deals with recent reports concerning degradation and rearrangement reactions of free sugars as well as some glycosides. The transformations are classified in chemical and enzymatic ways. In addition, the Maillard reaction will be discussed as an example of degradation and rearrangement transformation and its application in current research in the fields of chemistry and biology.

  16. International Water Center

    Science.gov (United States)

    The urban district of Nancy and the Town of Nancy, France, have taken the initiative of creating an International Center of Water (Centre International de l'Eau à Nancy—NAN.C.I.E.) in association with two universities, six engineering colleges, the Research Centers of Nancy, the Rhine-Meuse Basin Agency, and the Chamber of Commerce and Industry. The aim of this center is to promote research and technology transfer in the areas of water and sanitation. In 1985 it will initiate a research program drawing on the experience of 350 researchers and engineers of various disciplines who have already been assigned to research in these fields. The research themes, the majority of which will be multidisciplinary, concern aspects of hygiene and health, the engineering of industrial processes, water resources, and the environment and agriculture. A specialist training program offering five types of training aimed at university graduates, graduates of engineering colleges, or experts, will start in October 1984.

  17. Chemical reaction and separation method

    NARCIS (Netherlands)

    Jansen, J.C.; Kapteijn, F.; Strous, S.A.

    2005-01-01

    The invention is directed to process for performing a chemical reaction in a reaction mixture, which reaction produces water as by-product, wherein the reaction mixture is in contact with a hydroxy sodalite membrane, through which water produced during the reaction is removed from the reaction mixtu

  18. Patient-centered Care.

    Science.gov (United States)

    Reynolds, April

    2009-01-01

    Patient-centered care focuses on the patient and the individual's particular health care needs. The goal of patient-centered health care is to empower patients to become active participants in their care. This requires that physicians, radiologic technologists and other health care providers develop good communication skills and address patient needs effectively. Patient-centered care also requires that the health care provider become a patient advocate and strive to provide care that not only is effective but also safe. For radiologic technologists, patient-centered care encompasses principles such as the as low as reasonably achievable (ALARA) concept and contrast media safety. Patient-centered care is associated with a higher rate of patient satisfaction, adherence to suggested lifestyle changes and prescribed treatment, better outcomes and more cost-effective care. This article is a Directed Reading. Your access to Directed Reading quizzes for continuing education credit is determined by your area of interest. For access to other quizzes, go to www.asrt.org/store. According to one theory, most patients judge the quality of their healthcare much like they rate an airplane flight. They assume that the airplane is technically viable and is being piloted by competent people. Criteria for judging a particular airline are personal and include aspects like comfort, friendly service and on-time schedules. Similarly, patients judge the standard of their healthcare on nontechnical aspects, such as a healthcare practitioner's communication and "soft skills." Most are unable to evaluate a practitioner's level of technical skill or training, so the qualities they can assess become of the utmost importance in satisfying patients and providing patient-centered care.(1). PMID:19901351

  19. Center for Botanical Interaction Studies

    Data.gov (United States)

    Federal Laboratory Consortium — Research Area: Dietary Supplements, Herbs, Antioxidants Program:Centers for Dietary Supplements Research: Botanicals Description:This center will look at safety and...

  20. User Centered Design

    DEFF Research Database (Denmark)

    Egbert, Maria; Matthews, Ben

    2012-01-01

    The interdisciplinary approach of User Centered Design is presented here with a focus on innovation in the design and use of hearing technologies as well as on the potential of innovation in interaction. This approach is geared towards developing new products, systems, technologies and practices...... based on an understanding of why so few persons with hearing loss use the highly advanced hearing technologies. In integrating Conversation Analysis (“CA”), audiology and User Centered Design, three disciplines which are collaborating together for the first time, we are addressing the following...

  1. QUAD FAMILY CENTERING.

    Energy Technology Data Exchange (ETDEWEB)

    PINAYEV, I.

    2005-11-01

    It is well known that beam position monitors (BPM) utilizing signals from pickup electrodes (PUE) provide good resolution and relative accuracy. The absolute accuracy (i.e. position of the orbit in the vacuum chamber) is not very good due to the various reasons. To overcome the limitation it was suggested to use magnetic centers of quadrupoles for the calibration of the BPM [1]. The proposed method provides accuracy better then 200 microns for centering of the beam position monitors using modulation of the whole quadrupole family.

  2. Lied Transplant Center

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-01

    The Department of Energy has prepared an Environmental Assessment (DOE/EA-1143) evaluating the construction, equipping and operation of the proposed Lied Transplant Center at the University of Nebraska Medical Center in Omaha, Nebraska. Based on the analysis in the EA, the DOE has determined that the proposed action does not constitute a major federal action significantly affecting the quality of the human environment within the meaning of the National Environmental Policy Act of 1969 (NEPA). Therefore, the preparation of an Environmental Statement in not required.

  3. Xichang Satellite Launch Center

    Institute of Scientific and Technical Information of China (English)

    LiuJie

    2004-01-01

    Xichang Satellite Launch Center(XSLC) is mainly for geosynchronous orbit launches. The main purpose of XSLC is to launch spacecraft, such as broadcasting,communications and meteorological satellites, into geo-stationary orbit.Most of the commercial satellite launches of Long March vehicles have been from Xichang Satellite Launch Center. With 20 years' development,XSLC can launch 5 kinds of launch vehicles and send satellites into geostationary orbit and polar orbit. In the future, moon exploration satellites will also be launched from XSLC.

  4. Biochemical reaction engineering for redox reactions.

    Science.gov (United States)

    Wandrey, Christian

    2004-01-01

    Redox reactions are still a challenge for biochemical engineers. A personal view for the development of this field is given. Cofactor regeneration was an obstacle for quite some time. The first technical breakthrough was achieved with the system formate/formate dehydrogenase for the regeneration of NADH2. In cases where the same enzyme could be used for chiral reduction as well as for cofactor regeneration, isopropanol as a hydrogen source proved to be beneficial. The coproduct (acetone) can be removed by pervaporation. Whole-cell reductions (often yeast reductions) can also be used. By proper biochemical reaction engineering, it is possible to apply these systems in a continuous way. By cloning a formate dehydrogenase and an oxidoreductase "designer bug" can be obtained where formate is used instead of glucose as the hydrogen source. Complex sequences of redox reactions can be established by pathway engineering with a focus on gene overexpression or with a focus on establishing non-natural pathways. The success of pathway engineering can be controlled by measuring cytosolic metabolite concentrations. The optimal exploitation of such systems calls for the integrated cooperation of classical and molecular biochemical engineering.

  5. Effect of heavy metals on bacterial transport

    Science.gov (United States)

    Zhang, H.; Olson, M. S.

    2010-12-01

    Adsorption of metals onto bacteria and soil takes place as stormwater runoff infiltrates into the subsurface. Changes in both bacterial surfaces and soil elemental content have been observed, and may alter the attachment of bacteria to soil surfaces. In this study, scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDS) analyses were performed on soil samples equilibrated with synthetic stormwater amended with copper, lead and zinc. The results demonstrate the presence of copper and zinc on soil surfaces. To investigate bacterial attachment behavior, sets of batch sorption experiments were conducted on Escherichia Coli (E. coli) under different chemical conditions by varying solution compositions (nutrient solution vs synthetic stormwater). The adsorption data is best described using theoretical linear isotherms. The equilibrium coefficient (Kd) of E. coli is higher in synthetic stormwater than in nutrient solution without heavy metals. The adsorption of heavy metals onto bacterial surfaces significantly decreases their negative surface charge as determined via zeta potential measurements (-17.0±5.96mv for E. coli equilibrated with synthetic stormwater vs -21.6±5.45mv for E. coli equilibrated with nutrient solution), indicating that bacterial attachment may increase due to the attachment of metals onto bacterial surfaces and their subsequent change in surface charge. The attachment efficiency (α) of bacteria was also calculated and compared for both solution chemistries. Bacterial attachment efficiency (α) in synthetic stormwater is 0.997, which is twice as high as that in nutrient solution(α 0.465). The ratio of bacterial diameter : collector diameter suggests minimal soil straining during bacterial transport. Results suggest that the presence of metals in synthetic stormwater leads to an increase in bacterial attachment to soil surfaces. In terms of designing stormwater infiltration basins, the presence of heavy metals seems to

  6. Bacterial Gibberellins Induce Systemic Resistance of Plants

    Directory of Open Access Journals (Sweden)

    I. N. FEKLISTOVA

    2014-06-01

    Full Text Available It is generally agreed today that some rhizosphere bacteria can ensure induced systemic resistance to pathogens. In this paper we tested the ability of gibberellins produced by rhizosphere non-pathogenic bacteria Pseudomonas aurantiaca to induce systemic resistance to alternariosis agent – Alternaria brassicicola – in oilseed rape plants.Oilseed rape (Brássica nápus is one of the most promising oil-bearing croppers. It allows improving the supply of population with vegetable oil, animal and poultry industries with high quality vegetable protein. It is used for biofuel production as well.Gibberellin preparation was isolated from liquid culture of strain Pseudomonas aurantiaca grown in 250 mL of M9 medium (48 h, 28 °C under darkroom conditions. Gibberellins were extracted according procedure described by Tien et al. (1979. Gibberellins concentration in the medium was determined by fluorometric method.Elicitor activity of bacterial metabolites – gibberellins – was analyzed in model system of artificial inoculation of oilseed rape germs with phytopathogenic fungi Alternaria brassicicola. The elicitor action efficiency was evaluated on the 15th day of oilseed rape cultivation based on the percentage of leaf surface covered by necrotic lesions.Gibberellins were shown to induce systemic resistance resulted in decreasing of oil seed plants   vulnerability by 52.7%.It is known that under the unfavorable conditions plants synthesis the reactive oxygen intermediates   which activate destructive processes. One of the first organism reactions to stress action is the change of the lipid peroxidation level. It was shown that treatment of the soil with gibberellins resulted in decreasing of the lipid peroxidation level twofold.Gibberellins were shown to have a similar effect on permeability of cell membranes for free nucleotides. The permeability of cell membranes in leaves decreased 2.8-fold at room temperature. We suggest that gibberellins

  7. From Catalytic Reaction Networks to Protocells

    Science.gov (United States)

    Kaneko, Kunihiko

    2013-12-01

    In spite of recent advances, there still remains a large gape between a set of chemical reactions and a biological cell. Here we discuss several theoretical efforts to fill in the gap. The topics cover (i) slow relaxation to equilibrium due to glassy behavior in catalytic reaction networks (ii) consistency between molecule replication and cell growth, as well as energy metabolism (iii) control of a system by minority molecules in mutually catalytic system, which work as a carrier of genetic information, and leading to evolvability (iv) generation of a compartmentalized structure as a cluster of molecules centered around the minority molecule, and division of the cluster accompanied by the replication of minority molecule (v) sequential, logical process over several states from concurrent reaction dynamics, by taking advantage of discreteness in molecule number.

  8. Autoproteolytic Activation of Bacterial Toxins

    Directory of Open Access Journals (Sweden)

    Aimee Shen

    2010-05-01

    Full Text Available Protease domains within toxins typically act as the primary effector domain within target cells. By contrast, the primary function of the cysteine protease domain (CPD in Multifunctional Autoprocessing RTX-like (MARTX and Clostridium sp. glucosylating toxin families is to proteolytically cleave the toxin and release its cognate effector domains. The CPD becomes activated upon binding to the eukaryotic-specific small molecule, inositol hexakisphosphate (InsP6, which is found abundantly in the eukaryotic cytosol. This property allows the CPD to spatially and temporally regulate toxin activation, making it a prime candidate for developing anti-toxin therapeutics. In this review, we summarize recent findings related to defining the regulation of toxin function by the CPD and the development of inhibitors to prevent CPD-mediated activation of bacterial toxins.

  9. Cooperative Model of Bacterial Sensing

    CERN Document Server

    Shi, Y; Shi, Yu; Duke, Thomas

    1998-01-01

    Bacterial chemotaxis is controlled by the signalling of a cluster of receptors. A cooperative model is presented, in which coupling between neighbouring receptor dimers enhances the sensitivity with which stimuli can be detected, without diminishing the range of chemoeffector concentration over which chemotaxis can operate. Individual receptor dimers have two stable conformational states: one active, one inactive. Noise gives rise to a distribution between these states, with the probability influenced by ligand binding, and also by the conformational states of adjacent receptor dimers. The two-state model is solved, based on an equivalence with the Ising model in a randomly distributed magnetic field. The model has only two effective parameters, and unifies a number of experimental findings. According to the value of the parameter comparing coupling and noise, the signal can be arbitrarily sensitive to changes in the fraction of receptor dimers to which ligand is bound. The counteracting effect of a change of...

  10. Bacterial ice crystal controlling proteins.

    Science.gov (United States)

    Lorv, Janet S H; Rose, David R; Glick, Bernard R

    2014-01-01

    Across the world, many ice active bacteria utilize ice crystal controlling proteins for aid in freezing tolerance at subzero temperatures. Ice crystal controlling proteins include both antifreeze and ice nucleation proteins. Antifreeze proteins minimize freezing damage by inhibiting growth of large ice crystals, while ice nucleation proteins induce formation of embryonic ice crystals. Although both protein classes have differing functions, these proteins use the same ice binding mechanisms. Rather than direct binding, it is probable that these protein classes create an ice surface prior to ice crystal surface adsorption. Function is differentiated by molecular size of the protein. This paper reviews the similar and different aspects of bacterial antifreeze and ice nucleation proteins, the role of these proteins in freezing tolerance, prevalence of these proteins in psychrophiles, and current mechanisms of protein-ice interactions. PMID:24579057

  11. Unexpected versatility in bacterial riboswitches.

    Science.gov (United States)

    Mellin, J R; Cossart, Pascale

    2015-03-01

    Bacterial riboswitches are elements present in the 5'-untranslated regions (UTRs) of mRNA molecules that bind to ligands and regulate the expression of downstream genes. Riboswitches typically regulate the expression of protein-coding genes. However, mechanisms of riboswitch-mediated regulation have recently been shown to be more diverse than originally thought, with reports showing that riboswitches can regulate the expression of noncoding RNAs and control the access of proteins, such as transcription termination factor Rho and RNase E, to a nascent RNA. Riboswitches are also increasingly used in biotechnology, with advances in the engineering of synthetic riboswitches and the development of riboswitch-based sensors. In this review we address the emerging roles and mechanisms of riboswitch-mediated regulation in natura and recent progress in the development of riboswitch-based technology. PMID:25708284

  12. User-Centered Design through Learner-Centered Instruction

    Science.gov (United States)

    Altay, Burçak

    2014-01-01

    This article initially demonstrates the parallels between the learner-centered approach in education and the user-centered approach in design disciplines. Afterward, a course on human factors that applies learner-centered methods to teach user-centered design is introduced. The focus is on three tasks to identify the application of theoretical and…

  13. Economics of data center optics

    Science.gov (United States)

    Huff, Lisa

    2016-03-01

    Traffic to and from data centers is now reaching Zettabytes/year. Even the smallest of businesses now rely on data centers for revenue generation. And, the largest data centers today are orders of magnitude larger than the supercomputing centers of a few years ago. Until quite recently, for most data center managers, optical data centers were nice to dream about, but not really essential. Today, the all-optical data center - perhaps even an all-single mode fiber (SMF) data center is something that even managers of medium-sized data centers should be considering. Economical transceivers are the key to increased adoption of data center optics. An analysis of current and near future data center optics economics will be discussed in this paper.

  14. Variations in Bacterial Community in a Temperate Lake Associated with an Agricultural Watershed.

    Science.gov (United States)

    Song, Liyan; Li, Lei

    2016-08-01

    Terrestrially derived carbon and nutrients are washed into lakes, providing nutritional drivers for both microbial heterotrophy and phototrophy. Changes in the quantity and diversity of carbon and nutrients exported from watersheds in response to alterations in long-term land use have led to a need for evaluation of the linkage between watershed-exported carbon and nutrients and bacterial community structure in watershed associated lakes. To learn more about these interactions, we investigated Muskrat Lake in Michigan, which has a well-defined moderately sized watershed dominated by agriculture. We measured the water chemistry, characterized the dissolved organic carbon, and determined the structure of the bacterial communities at the inlet and center of this lake (five depths per site) over the summer and fall of 2008. The lake had temporal and rain event-based fluctuations in water chemistry, as well as temporal and rain event-dependent shifts in bacterial communities as measured by terminal restriction fragment length polymorphism. Agricultural watershed inputs were observed in the lake during and after rain events. Terminal restriction fragment length polymorphism and 454 pyrosequencing of the bacterial communities indicated that there were differences over time and that the dominant phylotypes shifted between summer and late fall. Some populations (e.g., Polynucleobacter and Mycobacterium) increased during fall, while others (e.g., Gemmatimonas) diminished. Redundancy and partitioning analyses showed that water chemistry is highly correlated with variations in the bacterial community of the lake, which explained 34 % of the variations in the bacterial community. Dissolved organic carbon had the greatest effects on variations in the Muskrat Lake bacterial community (2 %). The results of this study provide information that will enable a better understanding of the interaction between the bacterial community of lakes and changes in chemical properties as a

  15. Influence of hydrogen fluoride on kinetics of thermal reaction of hydrogen with chlorine monofluoride

    Energy Technology Data Exchange (ETDEWEB)

    Zhitneva, G.P.

    1986-07-01

    The influence of HF on the kinetics of the thermal reaction of H/sub 2/ with ClF in a fused quartz vessel was studied. It was shown that HF inbibits the reaction by blocking the reaction centers on the vessel surface, which lowers the rate of the heterogeneous generation of chains.

  16. Starting a sleep center.

    Science.gov (United States)

    Epstein, Lawrence J; Valentine, Paul S

    2010-05-01

    The demand for sleep medicine services has grown tremendously during the last decade and will likely continue. To date, growth in demand has been met by growth in the number of new sleep centers. The need for more new centers will be dependent on market drivers that include increasing regulatory requirements, personnel shortages, integration of home sleep testing, changes in reimbursement, a shift in emphasis from diagnostics to treatment, and an increased consumer focus on sleep. The decision to open a new center should be based on understanding the market dynamics, completing a market analysis, and developing a business plan. The business plan should include an overview of the facility, a personnel and organizational structure, an evaluation of the business environment, a financial plan, a description of services provided, and a strategy for obtaining, managing, and extending a referral base. Implementation of the business plan and successful operation require ongoing planning and monitoring of operational parameters. The need for new sleep centers will likely continue, but the shifting market dynamics indicate a greater need for understanding the marketplace and careful planning. PMID:20442123

  17. INTERMOUNTAIN INDUSTRIAL ASSESSMENT CENTER

    Energy Technology Data Exchange (ETDEWEB)

    MELINDA KRAHENBUHL

    2010-05-28

    The U. S. Department of Energy’s Intermountain Industrial Assessment Center (IIAC) at the University of Utah has been providing eligible small- and medium-sized manufacturers with no-cost plant assessments since 2001, offering cost-effective recommendations for improvements in the areas of energy efficiency, pollution prevention, and productivity improvement.

  18. The Rural Information Center.

    Science.gov (United States)

    John, Patricia La Caille

    1989-01-01

    Describes the events that led to the creation of the Rural Information Center (RIC), a joint venture between the Extension Service and the National Agricultural Library to provide information to government officials involved in rural development. The databases accessed by RIC are described, and plans for a gateway system and network of all…

  19. Carolinas Energy Career Center

    Energy Technology Data Exchange (ETDEWEB)

    Classens, Anver; Hooper, Dick; Johnson, Bruce

    2013-03-31

    Central Piedmont Community College (CPCC), located in Charlotte, North Carolina, established the Carolinas Energy Career Center (Center) - a comprehensive training entity to meet the dynamic needs of the Charlotte region's energy workforce. The Center provides training for high-demand careers in both conventional energy (fossil) and renewable energy (nuclear and solar technologies/energy efficiency). CPCC completed four tasks that will position the Center as a leading resource for energy career training in the Southeast: • Development and Pilot of a New Advanced Welding Curriculum, • Program Enhancement of Non-Destructive Examination (NDE) Technology, • Student Support through implementation of a model targeted toward Energy and STEM Careers to support student learning, • Project Management and Reporting. As a result of DOE funding support, CPCC achieved the following outcomes: • Increased capacity to serve and train students in emerging energy industry careers; • Developed new courses and curricula to support emerging energy industry careers; • Established new training/laboratory resources; • Generated a pool of highly qualified, technically skilled workers to support the growing energy industry sector.

  20. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... Flickr SlideShare All Pages & Documents Recalls & News Releases Home Recalls CPSC Recall API Recall Lawsuits Recalls by ... CO Poster Contest Toy Recall Statistics Pool Safely Home / Safety Education / Safety Education Centers En Español Carbon ...

  1. DISABILITY STATISTICS CENTER

    Science.gov (United States)

    The purpose of the Disability Statistics Center is to produce and disseminate statistical information on disability and the status of people with disabilities in American society and to establish and monitor indicators of how conditions are changing over time to meet their health...

  2. Memorial Alexander Center

    Directory of Open Access Journals (Sweden)

    AECK Associates, Arquitectos

    1958-05-01

    Full Text Available En Atlanta, el Instituto Tecnológico de Georgia acaba de ampliar sus instalaciones deportivas, construyendo el Alexander Memorial Center. Consta este nuevo Centro de dos edificios: una pista de baloncesto cubierta y un edificio anejo con vestuarios, duchas, una pista de entrenamiento, equipos técnicos y la emisora de radio Georgia Tech W. G. S. T.

  3. Carbon Monoxide Information Center

    Medline Plus

    Full Text Available ... an Unsafe Product Consumers Businesses Contact CPSC Website Design Feedback Consumers: Español Businesses: Español , 中文 , Tiếng Việt ... Chairman Commissioners Contact Information Agency Reports Legislative Affairs Job Opportunities Inspector General Safety Guides Safety Education Centers ...

  4. Precision Joining Center

    Energy Technology Data Exchange (ETDEWEB)

    Powell, J.W.; Westphal, D.A.

    1991-08-01

    A workshop to obtain input from industry on the establishment of the Precision Joining Center (PJC) was held on July 10--12, 1991. The PJC is a center for training Joining Technologists in advanced joining techniques and concepts in order to promote the competitiveness of US industry. The center will be established as part of the DOE Defense Programs Technology Commercialization Initiative, and operated by EG G Rocky Flats in cooperation with the American Welding Society and the Colorado School of Mines Center for Welding and Joining Research. The overall objectives of the workshop were to validate the need for a Joining Technologists to fill the gap between the welding operator and the welding engineer, and to assure that the PJC will train individuals to satisfy that need. The consensus of the workshop participants was that the Joining Technologist is a necessary position in industry, and is currently used, with some variation, by many companies. It was agreed that the PJC core curriculum, as presented, would produce a Joining Technologist of value to industries that use precision joining techniques. The advantage of the PJC would be to train the Joining Technologist much more quickly and more completely. The proposed emphasis of the PJC curriculum on equipment intensive and hands-on training was judged to be essential.

  5. vCenter troubleshooting

    CERN Document Server

    Mills, Chuck

    2015-01-01

    The book is designed for the competent vCenter administrator or anyone who is responsible for the vSphere environment. It can be used as a guide by vSphere architects and VMware consultants for a successful vSphere solution. You should have good knowledge and an understanding of core elements and applications of the vSphere environment.

  6. Patterns of bacterial diversity across a range of Antarctic terrestrial habitats.

    Science.gov (United States)

    Yergeau, Etienne; Newsham, Kevin K; Pearce, David A; Kowalchuk, George A

    2007-11-01

    Although soil-borne bacteria represent the world's greatest source of biological diversity, it is not well understood whether extreme environmental conditions, such as those found in Antarctic habitats, result in reduced soil-borne microbial diversity. To address this issue, patterns of bacterial diversity were studied in soils sampled along a > 3200 km southern polar transect spanning a gradient of increased climate severity over 27 degrees of latitude. Vegetated and fell-field plots were sampled at the Falkland (51 degrees S), South Georgia (54 degrees S), Signy (60 degrees S) and Anchorage Islands (67 degrees S), while bare frost-sorted soil polygons were examined at Fossil Bluff (71 degrees S), Mars Oasis (72 degrees S), Coal Nunatak (72 degrees S) and the Ellsworth Mountains (78 degrees S). Bacterial 16S rRNA gene sequences were recovered subsequent to direct DNA extraction from soil, polymerase chain reaction amplification and cloning. Although bacterial diversity was observed to decline with increased latitude, habitat-specific patterns appeared to also be important. Namely, a negative relationship was found between bacterial diversity and latitude for fell-field soils, but no such pattern was observed for vegetated sites. The Mars Oasis site, previously identified as a biodiversity hotspot within this region, proved exceptional within the study transect, with unusually high bacterial diversity. In independent analyses, geographical distance and vegetation cover were found to significantly influence bacterial community composition. These results provide insight into the factors shaping the composition of bacterial communities in Antarctic terrestrial habitats and support the notion that bacterial diversity declines with increased climatic severity.

  7. Bacterial colonization of colonic crypt mucous gel and disease activity in ulcerative colitis.

    LENUS (Irish Health Repository)

    Rowan, Fiachra

    2012-02-01

    OBJECTIVE: To optimize total bacterial 16S rRNA quantification in microdissected colonic crypts in healthy controls and patients with ulcerative colitis (UC) and to characterize the findings with disease activity. BACKGROUND: Microscopic and molecular techniques have recently converged to allow bacterial enumeration in remote anatomic locations [eg, crypt-associated mucous gel (CAMG)]. The aims of this study were to combine laser capture microdissection (LCM) and 16S rRNA-based quantitative polymerase chain reaction (qPCR) to determine total bacterial copy number in CAMG both in health and in UC and to characterize the findings with disease activity. METHODS: LCM was used to microdissect CAMG from colonic mucosal biopsies from controls (n = 20) and patients with acute (n = 10) or subacute (n = 10) UC. Pan-bacterial 16S rRNA copy number per millimeter square in samples from 6 locations across the large bowel was obtained by qPCR using Desulfovibrio desulfuricans as a reference strain. Copy numbers were correlated with the UC disease activity index (UCDAI) and the simple clinical colitis activity index (SCCAI). RESULTS: Bacterial colonization of CAMG was detectable in all groups. Copy numbers were significantly reduced in acute UC. In subacute colitis, there was a positive correlation between copy number and UCDAI and SCCAI in the ascending, transverse and sigmoid colon. CONCLUSIONS: This study describes a sensitive method of quantitatively assessing bacterial colonization of the colonic CAMG. A positive correlation was found between CAMG bacterial load and subacute disease activity in UC, whereas detectable bacterial load was reduced in acute UC.

  8. Center of Nuclear Physical Data (CNPD)

    International Nuclear Information System (INIS)

    This it the progress report of the Center of Nuclear Physical Data (CNPD) of the Russian Federal Nuclear Center-VNIIEF, Sarov, Russia. There have been compiled data on alpha-induced reactions for the nuclei with 8≤Z≤32 (24Mg, 28Si, 32S, 36Ar, 40Ca) and Ecm≤20 MeV. Processing of compiled data allowed obtaining parameters of Woods-Saxon potential with volume absorption in the α-particle energy range lower and higher than the Coulomb barrier for the 36Ar+α and 40Ca+α systems. They were obtained as a result of existing optical potentials modification and are intended to be used in a statistical Houser-Feshbach model widely applied in astrophysical calculations of nuclear reaction cross-sections. This year there has been completed the creation of a new 'SaBa' database version' library of evaluated and experimental data on charged particles interaction with light nuclei. The data on more than 120 reaction channels are available in it today. The library is oriented to solve astrophysics problems and contains information useful for the developers of astrophysics applications

  9. Use of Bacteriophages to control bacterial pathogens

    Science.gov (United States)

    Lytic bacteriophages can provide a natural method and an effective alternative to antibiotics to reduce bacterial pathogens in animals, foods, and other environments. Bacteriophages (phages) are viruses which infect bacterial cells and eventually kill them through lysis, and represent the most abun...

  10. Plant Natural Products Targeting Bacterial Virulence Factors.

    Science.gov (United States)

    Silva, Laura Nunes; Zimmer, Karine Rigon; Macedo, Alexandre José; Trentin, Danielle Silva

    2016-08-24

    Decreased antimicrobial efficiency has become a global public health issue. The paucity of new antibacterial drugs is evident, and the arsenal against infectious diseases needs to be improved urgently. The selection of plants as a source of prototype compounds is appropriate, since plant species naturally produce a wide range of secondary metabolites that act as a chemical line of defense against microorganisms in the environment. Although traditional approaches to combat microbial infections remain effective, targeting microbial virulence rather than survival seems to be an exciting strategy, since the modulation of virulence factors might lead to a milder evolutionary pressure for the development of resistance. Additionally, anti-infective chemotherapies may be successfully achieved by combining antivirulence and conventional antimicrobials, extending the lifespan of these drugs. This review presents an updated discussion of natural compounds isolated from plants with chemically characterized structures and activity against the major bacterial virulence factors: quorum sensing, bacterial biofilms, bacterial motility, bacterial toxins, bacterial pigments, bacterial enzymes, and bacterial surfactants. Moreover, a critical analysis of the most promising virulence factors is presented, highlighting their potential as targets to attenuate bacterial virulence. The ongoing progress in the field of antivirulence therapy may therefore help to translate this promising concept into real intervention strategies in clinical areas. PMID:27437994

  11. Bacterial cell division proteins as antibiotic targets

    NARCIS (Netherlands)

    T. den Blaauwen; J.M. Andreu; O. Monasterio

    2014-01-01

    Proteins involved in bacterial cell division often do not have a counterpart in eukaryotic cells and they are essential for the survival of the bacteria. The genetic accessibility of many bacterial species in combination with the Green Fluorescence Protein revolution to study localization of protein

  12. Recent advances in bacterial heme protein biochemistry

    OpenAIRE

    Mayfield, Jeffery A.; Dehner, Carolyn A.; Dubois, Jennifer L.

    2011-01-01

    Recent progress in genetics, fed by the burst in genome sequence data, has led to the identification of a host of novel bacterial heme proteins that are now being characterized in structural and mechanistic terms. The following short review highlights very recent work with bacterial heme proteins involved in the uptake, biosynthesis, degradation, and use of heme in respiration and sensing.

  13. Multiple bacterial species reside in chronic wounds

    DEFF Research Database (Denmark)

    Gjødsbøl, Kristine; Christensen, Jens Jørgen; Karlsmark, Tonny;

    2006-01-01

    The aim of the study was to investigate the bacterial profile of chronic venous leg ulcers and the importance of the profile to ulcer development. Patients with persisting venous leg ulcers were included and followed for 8 weeks. Every second week, ulcer samples were collected and the bacterial s...

  14. Bacterial biofilms: prokaryotic adventures in multicellularity

    DEFF Research Database (Denmark)

    Webb, J.S.; Givskov, Michael Christian; Kjelleberg, S.

    2003-01-01

    The development of bacterial biofilms includes both the initial social behavior of undifferentiated cells, as well as cell death and differentiation in the mature biofilm, and displays several striking similarities with higher organisms. Recent advances in the field provide new insight...... into differentiation and cell death events in bacterial biofilm development and propose that biofilms have an unexpected level of multicellularity....

  15. Barriers to bacterial motility on unsaturated surfaces

    DEFF Research Database (Denmark)

    Dechesne, Arnaud; Smets, Barth F.

    2013-01-01

    and their isogenic mutants unable to express various type of motility we aimed to quantify the physical limits of bacterial motility. Our results demonstrate how hydration controls bacterial motility under unsaturated conditions. They can form the base of improved biodegradation models that include microbial...

  16. Sustainable strategies for treatment of bacterial infections

    DEFF Research Database (Denmark)

    Molin, Søren

    2014-01-01

    not in a foreseeable future develop novel approaches and strategies to combat bacterial infections, many people will be at risk of dying from even trivial infections for which we until recently had highly effective antibiotics. We have for a number of years investigated chronic bacterial lung infections in patients...

  17. Hypersensitivity reactions to corticosteroids.

    Science.gov (United States)

    Vatti, Rani R; Ali, Fatima; Teuber, Suzanne; Chang, Christopher; Gershwin, M Eric

    2014-08-01

    Hypersensitivity reactions to corticosteroids (CS) are rare in the general population, but they are not uncommon in high-risk groups such as patients who receive repeated doses of CS. Hypersensitivity reactions to steroids are broadly divided into two categories: immediate reactions, typically occurring within 1 h of drug administration, and non-immediate reactions, which manifest more than an hour after drug administration. The latter group is more common. We reviewed the literature using the search terms "hypersensitivity to steroids, adverse effects of steroids, steroid allergy, allergic contact dermatitis, corticosteroid side effects, and type I hypersensitivity" to identify studies or clinical reports of steroid hypersensitivity. We discuss the prevalence, mechanism, presentation, evaluation, and therapeutic options in corticosteroid hypersensitivity reactions. There is a paucity of literature on corticosteroid allergy, with most reports being case reports. Most reports involve non-systemic application of corticosteroids. Steroid hypersensitivity has been associated with type I IgE-mediated allergy including anaphylaxis. The overall prevalence of type I steroid hypersensitivity is estimated to be 0.3-0.5%. Allergic contact dermatitis (ACD) is the most commonly reported non-immediate hypersensitivity reaction and usually follows topical CS application. Atopic dermatitis and stasis dermatitis of the lower extremities are risk factors for the development of ACD from topical CS. Patients can also develop hypersensitivity reactions to nasal, inhaled, oral, and parenteral CS. A close and detailed evaluation is required for the clinician to confirm the presence of a true hypersensitivity reaction to the suspected drug and choose the safest alternative. Choosing an alternative CS is not only paramount to the patient's safety but also ameliorates the worry of developing an allergic, and potentially fatal, steroid hypersensitivity reaction. This evaluation becomes

  18. Enteroviral pharyngitis diagnosed by reverse transcriptase-polymerase chain reaction.

    OpenAIRE

    Sharland, M.; Hodgson, J.; Davies, E G; Booth, J.; Jeffery, S

    1996-01-01

    The role of enteroviruses in childhood pharyngitis was investigated using enteroviral specific reverse transcriptase-polymerase chain reaction (RT-PCR). Viral/bacterial throat swabs were taken from 50 children with acute pharyngitis and 26 controls. A positive culture was identified in only 26% of children with pharyngitis (adenovirus 10%, group A streptococci 2%), and none of the controls. Enteroviral RT-PCR was positive in 8% of the pharyngitis group and none of the controls. Enteroviruses ...

  19. Electron transfer reactions

    CERN Document Server

    Cannon, R D

    2013-01-01

    Electron Transfer Reactions deals with the mechanisms of electron transfer reactions between metal ions in solution, as well as the electron exchange between atoms or molecules in either the gaseous or solid state. The book is divided into three parts. Part 1 covers the electron transfer between atoms and molecules in the gas state. Part 2 tackles the reaction paths of oxidation states and binuclear intermediates, as well as the mechanisms of electron transfer. Part 3 discusses the theories and models of the electron transfer process; theories and experiments involving bridged electron transfe

  20. The Reaction Wheel Pendulum

    CERN Document Server

    Block, Daniel J; Spong, Mark W

    2007-01-01

    This monograph describes the Reaction Wheel Pendulum, the newest inverted-pendulum-like device for control education and research. We discuss the history and background of the reaction wheel pendulum and other similar experimental devices. We develop mathematical models of the reaction wheel pendulum in depth, including linear and nonlinear models, and models of the sensors and actuators that are used for feedback control. We treat various aspects of the control problem, from linear control of themotor, to stabilization of the pendulum about an equilibrium configuration using linear control, t

  1. Enhancement of Au Dissolution by Microorganisms Using an Accelerating Cathode Reaction

    Science.gov (United States)

    Kita, Yoshito; Nishikawa, Hiroshi; Ike, Michihiko; Takemoto, Tadashi

    2009-02-01

    A Chromobacterium violaceum ( C. violaceum) strain that produces cyanide was used to dissolve Au. In this bacterial Au dissolution process, decreased dissolved oxygen concentration in the bacterial medium significantly inhibits Au dissolution. Although aeration is effective in increasing the level of dissolved oxygen in the bacterial medium, it is not effective in increasing Au dissolution during the growth phase of the bacteria because of the latter’s high respiratory consumption of oxygen. The present study investigated the utility of H2O2, rather than aeration, for increasing dissolved oxygen concentrations in bacterial growth medium. It was anticipated that the stronger oxidation reagent would increase Au dissolution by accelerating the cathode reaction during the bacterial growth phase. In fact, the addition of H2O2 to the bacterial culture increased dissolved oxygen concentrations in the growth phase and also drastically increased the dissolution rate of Au. Electrochemical measurements indicated that H2O2 addition to the bacterial medium accelerated the cathode reaction and thus enhanced Au dissolution by this biological process.

  2. Bibliographic index to photonuclear reaction data (1955--1992)

    Energy Technology Data Exchange (ETDEWEB)

    Asami, Tetsuo [Data Engineering, Inc., Yokohama (Japan); Nakagawa, Tsuneo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Dept. of Reactor Engineering

    1993-10-01

    Japanese Nuclear Data Committee (JNDC) has a plan to compile the evaluated data library for photon-induced nuclear reaction cross sections, and the work on the data evaluation is in progress at the present. In the evaluations for these data a bibliographic index for neutron nuclear data is required. As the bibliographic index to photonuclear reactions, several excellent compilations have been done at some research institutes in the world, and have contributed to various basic and applied researches on the photonuclear reactions. For example, there are the abstract sheets published by US National Bureau of Standards and the data index published regularly in Russia. On the other hand, the four-center network on nuclear data (US National Nuclear Data Center at Brookhaven, Russian Nuclear Data Center at Obninsk, NEA Data Bank at Paris and IAEA Nuclear Data Section at Vienna) compiles and exchanges the numerical data on photonuclear reactions as well as on neutron-induced ones, in the EXFOR format. Those numerical data are available for users. There is, however, no bibliographic index to photonuclear reactions, available for general users. Therefore, the present work to make a photonuclear reaction data index has been done urgently to contribute to the above-mentioned data evaluation. Although these data might be still incomplete and have some defects, we have decided to serve this as the first edition of our photonuclear reaction index.

  3. A Replisome's journey through the bacterial chromosome.

    Science.gov (United States)

    Beattie, Thomas R; Reyes-Lamothe, Rodrigo

    2015-01-01

    Genome duplication requires the coordinated activity of a multi-component machine, the replisome. In contrast to the background of metabolic diversity across the bacterial domain, the composition and architecture of the bacterial replisome seem to have suffered few changes during evolution. This immutability underlines the replisome's efficiency in copying the genome. It also highlights the success of various strategies inherent to the replisome for responding to stress and avoiding problems during critical stages of DNA synthesis. Here we summarize current understanding of bacterial replisome architecture and highlight the known variations in different bacterial taxa. We then look at the mechanisms in place to ensure that the bacterial replisome is assembled appropriately on DNA, kept together during elongation, and disassembled upon termination. We put forward the idea that the architecture of the replisome may be more flexible that previously thought and speculate on elements of the replisome that maintain its stability to ensure a safe journey from origin to terminus. PMID:26097470

  4. Structural biology of bacterial RNA polymerase.

    Science.gov (United States)

    Murakami, Katsuhiko S

    2015-05-11

    Since its discovery and characterization in the early 1960s (Hurwitz, J. The discovery of RNA polymerase. J. Biol. Chem. 2005, 280, 42477-42485), an enormous amount of biochemical, biophysical and genetic data has been collected on bacterial RNA polymerase (RNAP). In the late 1990s, structural information pertaining to bacterial RNAP has emerged that provided unprecedented insights into the function and mechanism of RNA transcription. In this review, I list all structures related to bacterial RNAP (as determined by X-ray crystallography and NMR methods available from the Protein Data Bank), describe their contributions to bacterial transcription research and discuss the role that small molecules play in inhibiting bacterial RNA transcription.

  5. Structural Biology of Bacterial RNA Polymerase

    Directory of Open Access Journals (Sweden)

    Katsuhiko S. Murakami

    2015-05-01

    Full Text Available Since its discovery and characterization in the early 1960s (Hurwitz, J. The discovery of RNA polymerase. J. Biol. Chem. 2005, 280, 42477–42485, an enormous amount of biochemical, biophysical and genetic data has been collected on bacterial RNA polymerase (RNAP. In the late 1990s, structural information pertaining to bacterial RNAP has emerged that provided unprecedented insights into the function and mechanism of RNA transcription. In this review, I list all structures related to bacterial RNAP (as determined by X-ray crystallography and NMR methods available from the Protein Data Bank, describe their contributions to bacterial transcription research and discuss the role that small molecules play in inhibiting bacterial RNA transcription.

  6. Vaccine Reaction Images

    Science.gov (United States)

    ... Del.icio.us Digg Facebook Google Bookmarks Technorati Yahoo MyWeb Updates Subscribe Listen Content source: National Center ... Del.icio.us Digg Facebook Google Bookmarks Technorati Yahoo MyWeb Subscribe to RSS Get email updates To ...

  7. American Overseas Research Centers Program

    Science.gov (United States)

    Office of Postsecondary Education, US Department of Education, 2012

    2012-01-01

    The American Overseas Research Centers Program provides grants to overseas research centers that are consortia of U.S. institutions of higher education to enable the centers to promote postgraduate research, exchanges, and area studies. Eligible applicants are those consortia of U.S. institutions of higher education centers that: (1) Receive more…

  8. Nucleon induced reactions

    International Nuclear Information System (INIS)

    The collection contains full texts of 37 contributions; all fall within the INIS Subject Scope. The topics treated include some unsolved problems of nuclear reactions and relevant problems of nuclear structure at low and intermediate energies. (Z.S.)

  9. Reaction Qualifications Revisited

    DEFF Research Database (Denmark)

    Lippert-Rasmussen, Kasper

    2009-01-01

      When, in a competitive sphere, people are selected on the basis of qualifications only, their chances of acquiring positions of advantage may seem to depend entirely upon their abilities, not discriminatory bias. However, if reaction qualifications - i.e. characteristics which contribute...... to a person's effectiveness by causing a favourable reaction in customers, co-workers etc. (for short: recipients) - are involved, this assumption is false. Building on work by Wertheimer, Mason, and Miller, this paper proposes an account of the reaction qualifications that count, from the point of view...... preferences, recipients should not respond to the applicant actually hired on the basis of their (the recipients') racial preferences. My account decomposes the meritocratic ideal into four separate norms, one of which applies to recipients rather than to selectors. Finally, it defends the view that reaction...

  10. Autocatalysis in reaction networks.

    Science.gov (United States)

    Deshpande, Abhishek; Gopalkrishnan, Manoj

    2014-10-01

    The persistence conjecture is a long-standing open problem in chemical reaction network theory. It concerns the behavior of solutions to coupled ODE systems that arise from applying mass-action kinetics to a network of chemical reactions. The idea is that if all reactions are reversible in a weak sense, then no species can go extinct. A notion that has been found useful in thinking about persistence is that of "critical siphon." We explore the combinatorics of critical siphons, with a view toward the persistence conjecture. We introduce the notions of "drainable" and "self-replicable" (or autocatalytic) siphons. We show that: Every minimal critical siphon is either drainable or self-replicable; reaction networks without drainable siphons are persistent; and nonautocatalytic weakly reversible networks are persistent. Our results clarify that the difficulties in proving the persistence conjecture are essentially due to competition between drainable and self-replicable siphons.

  11. Chemisorption And Precipitation Reactions

    Science.gov (United States)

    The transport and bioavailability of chemical components within soils is, in part, controlled by partitioning between solids and solution. General terms used to describe these partitioning reactions include chemisorption and precipitation. Chemisorption is inclusive of the suit...

  12. Ofloxacin induced hypersensitivity reaction

    Directory of Open Access Journals (Sweden)

    Hari Babu Ramineni

    2015-01-01

    Full Text Available Ofloxacin is a commonly used antimicrobial agent to combat various infections. The adverse profile of quinolones includes gastrointestinal symptoms, which are the most frequent, neuropsychiatric symptoms, hematologic abnormalities are less common. We report a rare case of ofloxacin induced hypersensitivity reaction in a 57 year old female patient with complaints of rashes over the axilla, upper limb and back, abdomen, thorax associated with exfoliation of skin all over the axilla associated with severe itching. Based on history and clinical examination patient was diagnosed as ofloxacin induced hypersensitivity reaction and was successfully treated with antihistamines and corticosteroids. Pharmacovigilance should be a part of patient care in order to reduce occurrence of adverse drug reaction and also encourage practitioners in reporting so as to gather more and more data regarding adverse drug reactions. [Int J Res Med Sci 2015; 3(1.000: 349-351

  13. Allergic reactions in anaesthesia

    DEFF Research Database (Denmark)

    Krøigaard, M; Garvey, L H; Menné, T;

    2005-01-01

    BACKGROUND: The aim of this retrospective survey of possible allergic reactions during anaesthesia was to investigate whether the cause suspected by anaesthetists involved corresponded with the cause found on subsequent investigation in the Danish Anaesthesia Allergy Centre (DAAC). METHODS: Case...... notes and anaesthetic charts from 111 reactions in 107 patients investigated in the DAAC were scrutinized for either suspicions of or warnings against specific substances stated to be the cause of the supposed allergic reaction. RESULTS: In 67 cases, one or more substances were suspected. In 49...... match, the right substance being suspected, but investigations showed an additional allergen or several substances, including the right substance being suspected. CONCLUSIONS: An informed guess is not a reliable way of determining the cause of a supposed allergic reaction during anaesthesia and may put...

  14. Adverse reactions to cosmetics

    OpenAIRE

    Dogra A; Minocha Y; Kaur S

    2003-01-01

    Adverse reaction to cosmetics constitute a small but significant number of cases of contact dermatitis with varied appearances. These can present as contact allergic dermatitis, photodermatitis, contact irritant dermatitis, contact urticaria, hypopigmentation, hyperpigmentotion or depigmentation, hair and nail breakage. Fifty patients were included for the study to assess the role of commonly used cosmetics in causing adverse reactions. It was found that hair dyes, lipsticks and surprisingly ...

  15. EXERCISE AND REACTION TIMES

    OpenAIRE

    Varun; Neeraj; Ushadhar; Yogesh; Rinku

    2015-01-01

    OBJECTIVES: Physical exercise provides multiple benefits to an individual. It is known that exercising regularly can prevent coronary heart disease, hypertension and obesity and improve flexibility. The effect of exercise on visual reaction time needs to be studied, a s the existing data on the benefit of aerobic exercise on psychomotor functions is insufficient. MATERIALS AND METHODS: Online Visual reaction time is measured before and after exercise. Subjects were ...

  16. Oxygen evolution reaction catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Haber, Joel A.; Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Jones, Ryan J.; Guevarra, Dan W.; Shinde, Aniketa A.

    2016-09-06

    An Oxygen Evolution Reaction (OER) catalyst includes a metal oxide that includes oxygen, cerium, and one or more second metals. In some instances, the cerium is 10 to 80 molar % of the metals in the metal oxide and/or the catalyst includes two or more second metals. The OER catalyst can be included in or on an electrode. The electrode can be arranged in an oxygen evolution system such that the Oxygen Evolution Reaction occurs at the electrode.

  17. Meson production in + reactions

    Indian Academy of Sciences (India)

    H Machner; M Betigeri; J Bojowald; A Budzanowski; A Chatterjee; J Ernst; L Freindl; D Frekers; W Garske; K Grewer; A Hamacher; J Ilieva; L Jarczyk; K Kilian; S Kliczewski; W Klimala; D Kolev; T Kutsarova; J Lieb; H Machner; A Magiera; H Nann; L Pentchev; H S Plendl; D Protić; B Razen; P Von Rossen; B J Roy; R Siudak; J Smyrski; R V Srikantiah; A Strzałkowski; R Tsenov; K Zwoll

    2001-08-01

    Total and differential cross sections for the reactions $p+d → 3He + 0 with = ; and + → 3H + + were measured with the GEM detector at COSY for beam momenta between threshold and the maximum of the corresponding baryon resonance. For both reactions a strong forward–backward asymmetry was found. The data were compared with model calculations. The aspect of isospin symmetry breaking is studied.

  18. The impact of shrimp farming effluent on bacterial communities in mangrove waters, Ceará, Brazil.

    Science.gov (United States)

    Sousa, O V; Macrae, A; Menezes, F G R; Gomes, N C M; Vieira, R H S F; Mendonça-Hagler, L C S

    2006-12-01

    The effects of shrimp farm effluents on bacterial communities in mangroves have been infrequently reported. Classic and molecular biology methods were used to survey bacterial communities from four mangroves systems. Water temperature, salinity, pH, total heterotrophic bacteria and maximum probable numbers of Vibrio spp. were investigated. Genetic profiles of bacterial communities were also characterized by polymerase chain reaction (PCR) amplification of eubacterial and Vibrio 16S rDNA using denaturing gradient gel electrophoresis (DGGE). Highest heterotrophic counts were registered in the mangrove not directly polluted by shrimp farming. The Enterobacteriaceae and Chryseomonas luteola dominated the heterotrophic isolates. Vibrio spp. pathogenic to humans and shrimps were identified. Eubacterial genetic profiles suggest a shared community structure independent of mangrove system. Vibrio genetic profiles were mangrove specific. Neither microbial counts nor genetic profiling revealed a significant decrease in species richness associated with shrimp farm effluent. The complex nature of mangrove ecosystems and their microbial communities is discussed.

  19. TRPA1 channels mediate acute neurogenic inflammation and pain produced by bacterial endotoxins

    Science.gov (United States)

    Meseguer, Victor; Alpizar, Yeranddy A.; Luis, Enoch; Tajada, Sendoa; Denlinger, Bristol; Fajardo, Otto; Manenschijn, Jan-Albert; Fernández-Peña, Carlos; Talavera, Arturo; Kichko, Tatiana; Navia, Belén; Sánchez, Alicia; Señarís, Rosa; Reeh, Peter; Pérez-García, María Teresa; López-López, José Ramón; Voets, Thomas; Belmonte, Carlos; Talavera, Karel; Viana, Félix

    2014-01-01

    Gram-negative bacterial infections are accompanied by inflammation and somatic or visceral pain. These symptoms are generally attributed to sensitization of nociceptors by inflammatory mediators released by immune cells. Nociceptor sensitization during inflammation occurs through activation of the Toll-like receptor 4 (TLR4) signalling pathway by lipopolysaccharide (LPS), a toxic by-product of bacterial lysis. Here we show that LPS exerts fast, membrane delimited, excitatory actions via TRPA1, a transient receptor potential cation channel that is critical for transducing environmental irritant stimuli into nociceptor activity. Moreover, we find that pain and acute vascular reactions, including neurogenic inflammation (CGRP release) caused by LPS are primarily dependent on TRPA1 channel activation in nociceptive sensory neurons, and develop independently of TLR4 activation. The identification of TRPA1 as a molecular determinant of direct LPS effects on nociceptors offers new insights into the pathogenesis of pain and neurovascular responses during bacterial infections and opens novel avenues for their treatment.

  20. Application Center 2000

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ 在NET Enterprise Servers中,Application Center 2000扮演着企业管理电子商务分布式应用程序的重要角色.ApplicationCenter 2000是可以建立在Windows 2000上的网站应用程序,能够有效率地管理、降低企业成本.它也是一个向外拓展的技术,且通过丛集服务(Cluster Service),可随需求增加其扩展性与可用性,以此降低随之而来的高成本和管理方式,以及提供配置(Deploy)丛集服务器的能力.

  1. Entanglement with Centers

    CERN Document Server

    Ma, Chen-Te

    2015-01-01

    Entanglement is a physical phenomenon that each state cannot be described individually. Entanglement entropy gives quantitative understanding to the entanglement. We use decomposition of the Hilbert space to discuss properties of the entanglement. Therefore, partial trace operator becomes important to define the reduced density matrix from different centers, which commutes with all elements in the Hilbert space, corresponding to different entanglement choices or different observations on entangling surface. Entanglement entropy is expected to satisfy the strong subadditivity. We discuss decomposition of the Hilbert space for the strong subadditivity and other related inequalities. The entanglement entropy with centers can be computed from the Hamitonian formulations systematically, provided that we know wavefunctional. In the Hamitonian formulation, it is easier to obtain symmetry structure. We consider massless $p$-form theory as an example. The massless $p$-form theory in ($2p+2)$-dimensions has global symm...

  2. 4 Exhibition Centers

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    China's convention and exhibition industry has grown rapidly in recent years, with some of the nation's key cities becoming hubs of internationally renowned expositions, spurred by the construction of new exhibition centers.In 2003, a total of 3,298 conventions and exhibitions were held in China, up from 3,075 in the previous year. The number is estimated to have hit 4,000 in 2004.

  3. COMPUTATIONAL SCIENCE CENTER

    Energy Technology Data Exchange (ETDEWEB)

    DAVENPORT,J.

    2004-11-01

    The Brookhaven Computational Science Center brings together researchers in biology, chemistry, physics, and medicine with applied mathematicians and computer scientists to exploit the remarkable opportunities for scientific discovery which have been enabled by modern computers. These opportunities are especially great in computational biology and nanoscience, but extend throughout science and technology and include for example, nuclear and high energy physics, astrophysics, materials and chemical science, sustainable energy, environment, and homeland security.

  4. Xanthomonas oryzae pv oryzae the Causal Agent of Bacterial Leaf Blight of rice: Isolation, Characterization, and Study of Transposon Mutagenesis

    Directory of Open Access Journals (Sweden)

    Abdjad Asih Nawangsih

    2011-04-01

    Full Text Available Xanthomonas oryzae pv oryzae the Causal Agent of Bacterial Leaf Blight of rice: Isolation, Characterization, and Study of Transposon Mutagenesis. X. oryzae pv. oryzae (Xoo causes bacterial leaf blight (BLB of rice (Oryza sativa L., a major disease that constrains production of the staple crop in many countries of the world. Identification of X. oryzae pv. oryzae (Xoo was conducted based on the disease symptoms, pathogenicity, morphological, physiological, and genetic characteristics of bacterial cultures isolated from the infected plants. Fifty bacterial isolates predicted as Xoo have been successfully isolated. They are aerobic, rod shaped, and Gram negative bacteria. The isolates were evaluated for their hypersensitivity in tobacco and pathogenicity in rice plant. Fifty isolates induced hypersensitive reaction in tobacco and showed pathogenicity symptom in rice in different length. Based on physiological test, hypersensitivity and pathogenicity reactions, three bacterial isolates strongly predicted as Xoo, i.e. STG21, STG42, and STG46, were non indole formation, non pigment fluorescent, hydrolyzed casein, catalase activity positive, but negative oxidase. Partial sequencing of 16S rRNA genes of STG21 and STG42 showed 80% and 82% homology with X. oryzae, respectively, while STG46 showed 84% homology with X. campestris. Mini-Tn5 transposon mutagenesis of STG21 generated one of the mutants (M5 lossed it’s ability to induce hypersensitive reaction in tobacco plant and deficient in pathogenicity on rice. The lesion length of rice leaf caused by the mutant M5 decreased up to 80%.

  5. Microfluidic Approaches to Bacterial Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Hee-Deung Park

    2012-08-01

    Full Text Available Bacterial biofilms—aggregations of bacterial cells and extracellular polymeric substrates (EPS—are an important subject of research in the fields of biology and medical science. Under aquatic conditions, bacterial cells form biofilms as a mechanism for improving survival and dispersion. In this review, we discuss bacterial biofilm development as a structurally and dynamically complex biological system and propose microfluidic approaches for the study of bacterial biofilms. Biofilms develop through a series of steps as bacteria interact with their environment. Gene expression and environmental conditions, including surface properties, hydrodynamic conditions, quorum sensing signals, and the characteristics of the medium, can have positive or negative influences on bacterial biofilm formation. The influences of each factor and the combined effects of multiple factors may be addressed using microfluidic approaches, which provide a promising means for controlling the hydrodynamic conditions, establishing stable chemical gradients, performing measurement in a high-throughput manner, providing real-time monitoring, and providing in vivo-like in vitro culture devices. An increased understanding of biofilms derived from microfluidic approaches may be relevant to improving our understanding of the contributions of determinants to bacterial biofilm development.

  6. EFFECTS OF BACTERIAL VAGINOSIS ON PERINATAL OUTCOME

    Directory of Open Access Journals (Sweden)

    Rajshree

    2014-02-01

    Full Text Available NTRODUCTION: Bacterial vaginosis is a condition in which the normal lactobacillus ( predominant vaginal flora is replaced with anaerobic bacteria , gardnerella vaginalis and mycoplasma hominis . Our study was designed to find out the effects of bacterial vaginosis on fetomaternal outcome in pregnant women . MATERIAL & METHODS: A prospective study was conducted in MGMCH , Jaipur from S eptember’12 to February ’13 . 100 women attending the antenatal clinic were recruited during their antenatal visit after 20 weeks of gestation and obs erved for presence of bacterial vaginosis and followed till pregnancy outcome . Prevalence of bacterial vaginosis was determined by Nugent and Amsel criteria . Maternal and neonatal morbidity were studied accordingly . RESULT: Prevalence of bacterial vagino sis by Nugent criteria was 19% . There was a significant association between the period of gestation at which the patient delivers and Nugent scoring of her gram stain picture (p=0 . 01 . Relationship between nursery admissions of baby and bacterial vaginosi s was found to be highly significant (p=0 . 01 . Out of the 100 babies delivered , 20% had low birth weight , 2% had birth asphyxia & Apgar score < 5 , 7% delivered prematurely & 14% babies had to be transferred to neonatal care units for various causes . CONCL USION: Bacterial vaginosis was found to be significantly associated with adverse pregnancy outcome in the form of increased risk of preterm delivery , low birth weight , birth asphyxia in neonate . It was also concluded that there was a definite role of trea tment because it can prevent a considerable number of preterm deliveries .

  7. Bacterial microleakage of aged adhesive restorations

    Directory of Open Access Journals (Sweden)

    Nevin Cobanoglu

    2015-01-01

    Full Text Available Objective: The aim of this study was to investigate the marginal bacterial leakage of two self-etch adhesive systems after long-term water storage. Materials and Methods: Class V cavities were prepared on the buccal and lingual surfaces of extracted premolar teeth. After the sterilization of the teeth, four cavities were not restored for control purposes, whereas the other teeth were divided into two groups (n = 16 cavities each: Clearfil Protect Bond (CPB, Clearfil SE Bond (CSE. After the application of the bonding agent, cavities were restored with a composite resin. Then, the teeth were thermo cycled, stored in saline solution for 6 months and put into a broth culture of Streptococcus mutans. The teeth were fixed, sectioned and stained using the Gram-Colour modified method. The stained sections were then evaluated under a light microscope. The bacterial leakage was scored as: 0 - absence of stained bacteria, 1 - bacterial staining along the cavity walls, 2 - bacterial staining within the cut dentinal tubules. The data were analysed using the Kruskal-Wallis and Mann-Whitney U-test (P = 0.05. Results: The bacterial staining was detected within the cut dentinal tubules in all control cavities, in three cavities in the CSE group and one cavity in the CPB group. There were no observed statistically significant differences between the bacterial penetrations of the two bonding systems (P > 0.05. Conclusion: Both bonding systems provided acceptable prevention of marginal bacterial leakage after long-term water storage.

  8. 5.3 Bacterial disease

    Institute of Scientific and Technical Information of China (English)

    1993-01-01

    930229 A study on the count of living BCGbacilli using BL and Fs methods.ZHANGJiguang (张继光),et al.Shanghai TuberculControl Center,200031.Chin J Tuberc &Respir Dis 1992;15(6):325—327.Counting of living BCG bacilli is an importantindicator for survellance of BCG quality.Presently the method of CFU recommended byWHO is still widely used.This study employsrapid bioluminescent trchnique which measuersATP in the BCG and the fluorescent staining

  9. BACTERIAL FLORA IN DIABETIC ULCER

    Directory of Open Access Journals (Sweden)

    Anitha Lavanya

    2015-04-01

    Full Text Available BACKGROUND : Diabetic foot infections are one of the most feared complications of diabetes. This study was undertaken to determine the common etiological agents of diabetic foot infections and their in vitro antibiotic susceptibility. METHODS : A prospective study was p erformed over a period of two years in a tertiary care hospital. The aerobic and anaerobic bacterial agents were isolated and their antibiotic susceptibility pattern was determined . RESULTS : One hundred patients with Diabetic ulcer were studied, of which 6 5 were males and 35 were females. Majority of patients were in the age group of 51 to 60 years (37% and polymicrobial etiology was 64 % and monomicrobial etiology was 36%. A total of 187 organisms were isolated of which 165 were aerobic and 22 were anaero bic. Most frequently isolated aerobic organisms were Pseudomonas Sp., Klebsiella Sp., E coli Sp., and Staphylococcus aureus. The common anaerobic organisms isolated were Peptostreptococcus Sp. And Bacterioids Sp. CONCLUSION : High prevalence of multi - drug r esistant pathogens was observed. Amikacin, Imipenem were active against gram - negative bacilli, while vancomycin was found to be active against gram - positive bacteria.

  10. Phenotypic plasticity in bacterial plasmids.

    Science.gov (United States)

    Turner, Paul E

    2004-01-01

    Plasmid pB15 was previously shown to evolve increased horizontal (infectious) transfer at the expense of reduced vertical (intergenerational) transfer and vice versa, a key trade-off assumed in theories of parasite virulence. Whereas the models predict that susceptible host abundance should determine which mode of transfer is selectively favored, host density failed to mediate the trade-off in pB15. One possibility is that the plasmid's transfer deviates from the assumption that horizontal spread (conjugation) occurs in direct proportion to cell density. I tested this hypothesis using Escherichia coli/pB15 associations in laboratory serial culture. Contrary to most models of plasmid transfer kinetics, my data show that pB15 invades static (nonshaking) bacterial cultures only at intermediate densities. The results can be explained by phenotypic plasticity in traits governing plasmid transfer. As cells become more numerous, the plasmid's conjugative transfer unexpectedly declines, while the trade-off between transmission routes causes vertical transfer to increase. Thus, at intermediate densities the plasmid's horizontal transfer can offset selection against plasmid-bearing cells, but at high densities pB15 conjugates so poorly that it cannot invade. I discuss adaptive vs. nonadaptive causes for the phenotypic plasticity, as well as potential mechanisms that may lead to complex transfer dynamics of plasmids in liquid environments. PMID:15166133

  11. Rheumatoid arthritis and bacterial infections

    Directory of Open Access Journals (Sweden)

    N L Prokopjeva

    2008-01-01

    Full Text Available To study features of bacterial infections course in pts with rheumatoid arthritis (RA and changes of laboratory measures after focus of infection sanation. Material and methods. 46 pts with definite rheumatoid arthritis were examined at the time of comorbid infection (Cl detection and after infection focus sanation. Bacteriological test with evaluation of flora sensitivity to antibiotics by disco-diffusion method was performed at baseline and after the course of antibacterial therapy to assess its efficacy. Hemogram, serum fibrinogen, rheumatoid factor, circulating immune complexes (CIC, C-reactive protein levels were assessed. Serum interleukin (IL 1(3, IL6 and neopterin concentrations were examined by immune-enzyme assay in a part of pts. Typical clinical features of Cl were present in only 28 (60,9% pts. 13 (28,3% pts had fever, 12 (26,0% — leukocytosis, 15 (32,6% — changes of leucocyte populations. Some laboratory measures (thrombocytes, fibrinogen, CIC, neopterin levels significantly decreased (p<0,05 after infection focus sanation without correction of disease modifying therapy. Cl quite often develop as asymptomatic processes most often in pts with high activity and can induce disturbances promoting appearance of endothelial dysfunction, atherothrombosis and reduction of life duration. So timely detection and proper sanation of infection focuses should be performed in pts with RA

  12. Theoretical Study on the Reaction Mechanism of F2+2HBr=2HF+Br2

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The gas phase reaction mechanism of F2 + 2HBr = 2HF + Br2 has been investigated by (U)MP2 at 6-311G** level, and a series of four-center and three-center transition states have been obtained. The reaction mechanism was achieved by comparing the activation energy of seven reaction paths, i.e. the dissociation energy of F2 is less than the activation energy of the bimolecular elementary reaction F2 + HBr → HF + BrF. Thus it is theoretically proved that the title reaction occurs more easily inthe free radical reaction with three medium steps.

  13. Bacterial binding to extracellular proteins - in vitro adhesion

    DEFF Research Database (Denmark)

    Schou, C.; Fiehn, N.-E.

    1999-01-01

    Viridans streptococci, bacterial adherence, extracellular matrix proteins, surface receptors, endocarditis......Viridans streptococci, bacterial adherence, extracellular matrix proteins, surface receptors, endocarditis...

  14. Evidence of major genes affecting resistance to bacterial cold water disease in rainbow trout using Bayesian methods of segregation analysis

    Science.gov (United States)

    Bacterial cold water disease (BCWD) causes significant economic loss in salmonid aquaculture. We previously detected genetic variation for BCWD resistance in our rainbow trout population, and a family-based selection program to improve resistance was initiated at the National Center for Cool and Col...

  15. Biochemistry of Bacterial Multidrug Efflux Pumps

    Directory of Open Access Journals (Sweden)

    Sanath Kumar

    2012-04-01

    Full Text Available Bacterial pathogens that are multi-drug resistant compromise the effectiveness of treatment when they are the causative agents of infectious disease. These multi-drug resistance mechanisms allow bacteria to survive in the presence of clinically useful antimicrobial agents, thus reducing the efficacy of chemotherapy towards infectious disease. Importantly, active multi-drug efflux is a major mechanism for bacterial pathogen drug resistance. Therefore, because of their overwhelming presence in bacterial pathogens, these active multi-drug efflux mechanisms remain a major area of intense study, so that ultimately measures may be discovered to inhibit these active multi-drug efflux pumps.

  16. Tobacco use increases susceptibility to bacterial infection

    Directory of Open Access Journals (Sweden)

    Demuth Donald R

    2008-12-01

    Full Text Available Abstract Active smokers and those exposed to secondhand smoke are at increased risk of bacterial infection. Tobacco smoke exposure increases susceptibility to respiratory tract infections, including tuberculosis, pneumonia and Legionnaires disease; bacterial vaginosis and sexually transmitted diseases, such as chlamydia and gonorrhoea; Helicobacter pylori infection; periodontitis; meningitis; otitis media; and post-surgical and nosocomial infections. Tobacco smoke compromises the anti-bacterial function of leukocytes, including neutrophils, monocytes, T cells and B cells, providing a mechanistic explanation for increased infection risk. Further epidemiological, clinical and mechanistic research into this important area is warranted.

  17. Bacterial gasotransmitters: an innate defense against antibiotics.

    Science.gov (United States)

    Luhachack, Lyly; Nudler, Evgeny

    2014-10-01

    In recent decades, there has been growing interest in the field of gasotransmitters, endogenous gaseous signaling molecules (NO, H2S, and CO), as regulators of a multitude of biochemical pathways and physiological processes. Most of the concerted effort has been on eukaryotic gasotransmitters until the subsequent discovery of bacterial counterparts. While the fundamental aspects of bacterial gasotransmitters remain undefined and necessitate further research, we will discuss a known specific role they play in defense against antibiotics. Considering the current dilemma of multidrug-resistant bacteria we consider it particularly prudent to exploring novel targets and approaches, of which the bacterial gasotransmitters, nitric oxide and hydrogen sulfide represent.

  18. Spontaneous Bacterial Peritonitis in Subclinical Hypothyroidism

    Directory of Open Access Journals (Sweden)

    Dalip Gupta

    2013-11-01

    Full Text Available Hypothyroidism is an uncommon cause of ascites. Here we describe a case of a 75 year-old female patient with spontaneous bacterial peritonitis and subclinical hypothyroidism that resolved with thyroid replacement and antibiotic therapy respectively. Ascitic fluid analysis revealed a gram-positive bacterium on gram staining. A review of the literature revealed just one other reported case of myxoedema ascites with concomitant spontaneous bacterial peritonitis and no case has till been reported of spontaneous bacterial peritonitis in subclinical hypothyroidism.

  19. Target Product Profile for a Diagnostic Assay to Differentiate between Bacterial and Non-Bacterial Infections and Reduce Antimicrobial Overuse in Resource-Limited Settings: An Expert Consensus

    Science.gov (United States)

    Dittrich, Sabine; Tadesse, Birkneh Tilahun; Moussy, Francis; Chua, Arlene; Zorzet, Anna; Tängdén, Thomas; Dolinger, David L.; Page, Anne-Laure; Crump, John A.; D’Acremont, Valerie; Bassat, Quique; Lubell, Yoel; Newton, Paul N.; Heinrich, Norbert; Rodwell, Timothy J.; González, Iveth J.

    2016-01-01

    Acute fever is one of the most common presenting symptoms globally. In order to reduce the empiric use of antimicrobial drugs and improve outcomes, it is essential to improve diagnostic capabilities. In the absence of microbiology facilities in low-income settings, an assay to distinguish bacterial from non-bacterial causes would be a critical first step. To ensure that patient and market needs are met, the requirements of such a test should be specified in a target product profile (TPP). To identify minimal/optimal characteristics for a bacterial vs. non-bacterial fever test, experts from academia and international organizations with expertise in infectious diseases, diagnostic test development, laboratory medicine, global health, and health economics were convened. Proposed TPPs were reviewed by this working group, and consensus characteristics were defined. The working group defined non-severely ill, non-malaria infected children as the target population for the desired assay. To provide access to the most patients, the test should be deployable to community health centers and informal health settings, and staff should require 90% and >80% for sensitivity and specificity, respectively. Other key characteristics, to account for the challenging environment at which the test is targeted, included: i) time-to-result <10 min (but maximally <2 hrs); ii) storage conditions at 0–40°C, ≤90% non-condensing humidity with a minimal shelf life of 12 months; iii) operational conditions of 5–40°C, ≤90% non-condensing humidity; and iv) minimal sample collection needs (50–100μL, capillary blood). This expert approach to define assay requirements for a bacterial vs. non-bacterial assay should guide product development, and enable targeted and timely efforts by industry partners and academic institutions. PMID:27559728

  20. 低钠盐火腿肠保质期预测及产品致病菌的聚合酶链式反应检测%Shelf-Life Prediction and Pathogenic Bacterial Detection of Low-Sodium Salt Pork Sausages by Polymerase Chain Reaction

    Institute of Scientific and Technical Information of China (English)

    黄梅香; 王海滨; 李睿; 王宏勋; 从浩

    2012-01-01

    采用加速破坏性试验模型预测低钠盐火腿肠的保质期,并采用聚合酶链式反应对产品致病菌进行快速检测,同时对贮藏期间火腿肠的质构(嫩度)变化进行分析。结果表明:对照组(3%普通碘盐+0.3%磷酸盐)、2.5%市售低钠盐+0.35%TG组、2.0%市售低钠盐+0.3%磷酸盐组、3%多组分替代盐(NaCl 40%、KCl 35%、CaCl215%和甘氨酸10%)+0.35%TG组火腿肠在室温(25℃)和低温(4℃)条件下的保质期分别为17.5、17.6、16.9、15.7d和189、208、142、146d;产品在低温(4℃)条件下放置1个月后,各组均无致病菌检出;火腿肠在低温贮藏90d期间,其嫩度变化趋势是先增大后减小。综合比较而言,添加2.5%市售低钠盐+0.35%TG组火腿肠的贮藏稳定性最好。%The shelf-life of low-sodium pork sausages was predicted with accelerated shelf-life test model and pathogenic bacteria were detected by polymerase chain reaction (PCR) in this study. Meanwhile, the change trends of texture (tenderness) were also explored during storage. The results showed that the shelf-life of four kinds of pork sausages with the addition of 3% common iodine salt and 0.3% sodium tripolyphosphate (control group), the addition of 2.5% low-sodium salt and 0.35% TG, the addition of 2.0% low-sodium salt and 0.3% sodium tripolyphosphate, and the addition of 3% multi-component salt substitute (consisting of 40% NaC1, 35% KC1, 15% CaC12, and 10% aminoacetic acid) and 0.35% TG were 17.5, 17.6, 16.9 days and 15.7 days at room temperature (25 ℃), and 189, 208, 142 days and 146 days at 4 ℃, respectively. No pathogenic bacteria were detected after 1 month of storage at 4 ℃. The tenderness of all groups exhibited an initial increase and final decrease during 90 days storage at 4 ℃. Moreover, pork sausages with the addition of 2.5% low-sodium salt and 0.35% TG had the best storage stability.