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Alba A. Trespalacios,William Otero,Jorge E. Caminos,Marcela M. Mercado,Jenny Ávila,Liliana E. Rosero,Azucena Arévalo,Raúl A. Poutou-Piñales,David Y. Graham 한국미생물학회 2013 The journal of microbiology Vol.51 No.4
Resistance of Helicobacter pylori to clarithromycin is the most common cause of treatment failure in patients with H. pylori infections. This study describes the MICs and the presence of 23S rRNA mutations of H. pylori isolates from Bogotá, D.C., Colombia. H. pylori were isolated from gastric biopsies from patients with functional dyspepsia. Clarithromycin susceptibility was investigated by agar dilution and strains were considered resistant if the MIC was ≥1 μg/ml. DNA sequences of the 23S rRNA gene of strains resistant and sensitive to clarithromycin were determined to identify specific point mutations. Clarithromycin resistance was present in 13.6% of patients by agar dilution. The A2143G,A2142G and A2142C mutations were found in 90.5, 7.1, and 2.4% of H. pylori strains with resistance genotype.The resistant phenotype was associated with 23S rRNA resistance genotype in 85.7% of isolates. The point mutations in 23S rRNA were well correlated with MICs values for clarithromycin.
Degradation of thin carbon-backed lithium fluoride targets bombarded by 68 MeV 17O beams
김용현,Davids B.,Williams M.,Hudson K.H.,Upadhyayula S.,Alcorta M.,Machule P.,Esker N.E.,Griffin C.J.,Williams J.,Yates D.,Lennarz A.,Angus C.,Hackman G.,김동건,J. Son,Park J.,Pak K.,김용균 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3
To analyze the cause of the destruction of thin, carbon-backed lithium fluoride targets during a measurement of the fusion of 7Li and 17O, we estimate theoretically the lifetimes of carbon and LiF films due to sputtering, thermal evaporation, and lattice damage and compare them with the lifetime observed in the experiment. Sputtering yields and thermal evaporation rates in carbon and LiF films are too low to play significant roles in the destruction of the targets.We estimate the lifetime of the target due to lattice damage of the carbon backing and the LiF film using a previously reported model. In the experiment, elastically scattered target and beam ions were detected by surface silicon barrier (SSB) detectors so that the product of the beam flux and the target density could be monitored during the experiment. The areas of the targets exposed to different beam intensities and fluences were degraded and then perforated, forming holes with a diameter around the beam spot size. Overall, the target thickness tends to decrease linearly as a function of the beam fluence. However, the thickness also exhibits an increasing interval after SSB counts per beam ion decreases linearly, extending the target lifetime. The lifetime of thin LiF film as determined by lattice damage is calculated for the first time using a lattice damage model, and the calculated lifetime agrees well with the observed target lifetime during the experiment. In experiments using a thin LiF target to induce nuclear reactions, this study suggests methods to predict the lifetime of the LiF film and arrange the experimental plan for maximum efficiency
Type VI secretion is a major virulence determinant in <i>Burkholderia mallei</i>
Schell, Mark A.,Ulrich, Ricky L.,Ribot, Wilson J.,Brueggemann, Ernst E.,Hines, Harry B.,Chen, Dan,Lipscomb, Lyla,Kim, H. Stanley,Mrá,zek, Jan,Nierman, William C.,DeShazer, David Blackwell Publishing Ltd 2007 Molecular microbiology Vol.64 No.6
<P><B>Summary</B></P><P> <I>Burkholderia mallei</I> is a host‐adapted pathogen and a category B biothreat agent. Although the <I>B. mallei</I> VirAG two‐component regulatory system is required for virulence in hamsters, the virulence genes it regulates are unknown. Here we show with expression profiling that overexpression of <I>virAG</I> resulted in transcriptional activation of ∼60 genes, including some involved in capsule production, actin‐based intracellular motility, and type VI secretion (T6S). The 15 genes encoding the major sugar component of the homopolymeric capsule were up‐expressed > 2.5‐fold, but capsule was still produced in the absence of <I>virAG</I>. Actin tail formation required <I>virAG</I> as well as <I>bimB</I>, <I>bimC</I> and <I>bimE</I>, three previously uncharacterized genes that were activated four‐ to 15‐fold when VirAG was overproduced. Surprisingly, actin polymerization was found to be dispensable for virulence in hamsters. In contrast, genes encoding a T6S system were up‐expressed as much as 30‐fold and mutations in this T6S gene cluster resulted in strains that were avirulent in hamsters. SDS‐PAGE and mass spectrometry demonstrated that BMAA0742 was secreted by the T6S system when <I>virAG</I> was overexpressed. Purified His‐tagged BMAA0742 was recognized by glanders antiserum from a horse, a human and mice, indicating that this Hcp‐family protein is produced <I>in vivo</I> during infection.</P>
Golovich, Nathan,Weeren, Reinout J. van,Dawson, William A.,Jee, M. James,Wittman, David American Astronomical Society 2017 The Astrophysical journal Vol.838 No.2
<P>We present and analyze a rich data set including Subaru/SuprimeCam, HST/Advanced Camera for Surveys and Wide Field Camera 3, Keck/DEIMOS, Chandra/ACIS-I, and JVLA/C and D array for the merging cluster of galaxies ZwCl 0008.8+ 5215. With a joint Subaru+ HST weak gravitational lensing analysis, we identify two dominant subclusters and estimate the masses to be M-200 = 5.8(-1.8)(+2.8) x 10(14) M-circle dot. We estimate the projected separation between the two subclusters to be 924(-206)(+243) kpc. We perform a clustering analysis of spectroscopically confirmed cluster member galaxies and estimate the line-of-sight velocity difference between the two subclusters to be 92 +/- 164 km s(-1). We further motivate, discuss, and analyze the merger scenario through an analysis of the 42 ks of Chandra/ACIS-I and JVLA/C and D array polarization data. The X-ray surface brightness profile reveals a merging gas-core reminiscent of the Bullet Cluster. The global X-ray luminosity in the 0.5-7.0 keV band is 1.7. +/- 0.1 x 10(44) erg s(-1) and the global X-ray temperature is 4.90 +/- 0.13 keV. The radio relics are polarized up to 40%,. and along with the masses, velocities, and positions of the two subclusters, we input these quantities into a Monte Carlo dynamical analysis and estimate the merger velocity at pericenter to be 1800(-300)(+400) km s(-1). This is a lower-mass version of the Bullet Cluster and therefore may prove useful in testing alternative models of dark matter (DM). We do not find significant offsets between DM and galaxies, but the uncertainties are large with the current lensing data. Furthermore, in the east, the BCG is offset from other luminous cluster galaxies, which poses a puzzle for defining DM-galaxy offsets.</P>
Pai, Sung-Yun,Kim, Chaekyun,Williams, David A. IOS Press 2010 Disease markers Vol.29 No.3
<P>Rho GTPases are members of the Ras superfamily of GTPases that regulate a wide variety of cellular functions. While Rho GTPase pathways have been implicated in various pathological conditions in humans, to date coding mutations in only the hematopoietic specific GTPase, <I>RAC2</I>, have been found to cause a human disease, a severe phagocytic immunodeficiency characterized by life-threatening infections in infancy. Interestingly, the phenotype was predicted by a mouse knock-out of <I>RAC2</I> and resembles leukocyte adhesion deficiency (LAD). Here we review Rho GTPases with a specific focus on Rac GTPases. In particular, we discuss a new understanding of the unique and overlapping roles of Rac2 in blood cells that has developed since the generation of mice deficient in Rac1, Rac2 and Rac3 proteins. We propose that Rac2 mutations leading to disease be termed LAD type IV.</P>
James A. Smith,Casey J. Jesse,William A. Hanson,Clark L. Scott,David L. Cottle Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.6
One of the salient nuclear fuel performance parameters for new fuel types under development is changes in fuel thickness. To test the new commercially fabricated U-10Mo monolithic plate-type fuel, an irradiation experiment was designed that consisted of multiple mini-plate capsules distributed within the Advanced Test Reactor (ATR) core, the mini-plate 1 (MP-1) experiment. Each capsule contains eight mini-plates that were either fueled or "dummy" plates. Fuel thickness changes within a fuel assembly can be characterized by measuring the gaps between the plates ultrasonically. The channel gap probe (CGP) system is designed to measure the gaps between the plates and will provide information that supports qualification of U-10Mo monolithic fuel. This study will discuss the design and the results from the use of a custom-designed CGP system for characterizing the gaps between mini-plates within the MP-1 capsules. To ensure accurate and repeatable data, acceptance and calibration procedures have been developed. Unfortunately, there is no "gold" standard measurement to compare to CGP measurements. An effort was made to use plate thickness obtained from post-irradiation measurements to derive channel gap estimates for comparison with the CGP characterization.
Yuan, Langtian,Seo, Jin-Soo,Kang, Nam Sook,Keinan, Shahar,Steele, Sarah E.,Michelotti, Gregory A.,Wetsel, William C.,Beratan, David N.,Gong, Young-Dae,Lee, Tong H.,Hong, Jiyong Royal Society of Chemistry 2009 Molecular bioSystems Vol.5 No.9
<P>From a screen of small molecule libraries to identify potential therapeutics for psychostimulant abuse, 3-hydroxy-2-(3-hydroxyphenyl)-4<I>H</I>-1-benzopyran-4-ones were shown to be isoform-selective PKC-ζ inhibitors.</P> <P>Graphic Abstract</P><P>3-hydroxy-2-(3-hydroxyphenyl)-4<I>H</I>-1-benzopyran-4-ones were shown to be isoform-selective PKC-ζ inhibitors. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b903036k'> </P>
( Kwei Chee Kuan ),( David Lewis ),( Keith King ),( William Donohue ),( Brett A. Neilan ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.4
Cyanobacterial strains of the genus Spirulina have recently been identified as an excellent source of sulfolipids, some of which possess anti-HIV properties. Thus, to investigate the distribution of sufolipid biosynthesis pathways in Spirulina, a genetic screening/phylogentic study was performed. Five different strains of Spirulina [Spirulina (Jiangmen), Spirulina sp., S. platensis, S. maxima, and Spirulina seawater] sourced from different locations wereinitially classified via 16S rDNA sequencing, and then screened for the presence of the sulfolipid biosynthesis genes sqdB and sqdX via a PCR. To assess the suitability of these strains for human consumption and safe therapeutic use, the strains were also screened for the presence of genes encoding nonribosomal peptide synthases (NRPSs) and polyketide synthases (PKSs), which are often associated with toxin pathways in cyanobacteria. The results of the 16S rDNA analysis and phylogenetic study indicated that Spirulina sp. is closely related to Halospirulina, whereas the other four Spirulina strains are closely related to Arthrospira. Homologs of sqdB and sqdX were identified in Spirulina (Jiangmen), Spirulina sp., S. platensis, and the Spirulina seawater. None of the Spirulina strains screened in this study tested positive for NRPS or PKS genes, suggesting that these strains do not produce NRP or PK toxins.