Metagenomic profiling of microbial composition and antibiotic resistance determinants in Puget Sound.

Science.gov (United States)

Port, Jesse A; Wallace, James C; Griffith, William C; Faustman, Elaine M

2012-01-01

Human-health relevant impacts on marine ecosystems are increasing on both spatial and temporal scales. Traditional indicators for environmental health monitoring and microbial risk assessment have relied primarily on single species analyses and have provided only limited spatial and temporal information. More high-throughput, broad-scale approaches to evaluate these impacts are therefore needed to provide a platform for informing public health. This study uses shotgun metagenomics to survey the taxonomic composition and antibiotic resistance determinant content of surface water bacterial communities in the Puget Sound estuary. Metagenomic DNA was collected at six sites in Puget Sound in addition to one wastewater treatment plant (WWTP) that discharges into the Sound and pyrosequenced. A total of ~550 Mbp (1.4 million reads) were obtained, 22 Mbp of which could be assembled into contigs. While the taxonomic and resistance determinant profiles across the open Sound samples were similar, unique signatures were identified when comparing these profiles across the open Sound, a nearshore marina and WWTP effluent. The open Sound was dominated by α-Proteobacteria (in particular Rhodobacterales sp.), γ-Proteobacteria and Bacteroidetes while the marina and effluent had increased abundances of Actinobacteria, β-Proteobacteria and Firmicutes. There was a significant increase in the antibiotic resistance gene signal from the open Sound to marina to WWTP effluent, suggestive of a potential link to human impacts. Mobile genetic elements associated with environmental and pathogenic bacteria were also differentially abundant across the samples. This study is the first comparative metagenomic survey of Puget Sound and provides baseline data for further assessments of community composition and antibiotic resistance determinants in the environment using next generation sequencing technologies. In addition, these genomic signals of potential human impact can be used to guide initial

Metagenomic profiling of microbial composition and antibiotic resistance determinants in Puget Sound.

Directory of Open Access Journals (Sweden)

Jesse A Port

Full Text Available Human-health relevant impacts on marine ecosystems are increasing on both spatial and temporal scales. Traditional indicators for environmental health monitoring and microbial risk assessment have relied primarily on single species analyses and have provided only limited spatial and temporal information. More high-throughput, broad-scale approaches to evaluate these impacts are therefore needed to provide a platform for informing public health. This study uses shotgun metagenomics to survey the taxonomic composition and antibiotic resistance determinant content of surface water bacterial communities in the Puget Sound estuary. Metagenomic DNA was collected at six sites in Puget Sound in addition to one wastewater treatment plant (WWTP that discharges into the Sound and pyrosequenced. A total of ~550 Mbp (1.4 million reads were obtained, 22 Mbp of which could be assembled into contigs. While the taxonomic and resistance determinant profiles across the open Sound samples were similar, unique signatures were identified when comparing these profiles across the open Sound, a nearshore marina and WWTP effluent. The open Sound was dominated by α-Proteobacteria (in particular Rhodobacterales sp., γ-Proteobacteria and Bacteroidetes while the marina and effluent had increased abundances of Actinobacteria, β-Proteobacteria and Firmicutes. There was a significant increase in the antibiotic resistance gene signal from the open Sound to marina to WWTP effluent, suggestive of a potential link to human impacts. Mobile genetic elements associated with environmental and pathogenic bacteria were also differentially abundant across the samples. This study is the first comparative metagenomic survey of Puget Sound and provides baseline data for further assessments of community composition and antibiotic resistance determinants in the environment using next generation sequencing technologies. In addition, these genomic signals of potential human impact can be used

Prevalence of plasmid-mediated quinolone resistance determinants among oxyiminocephalosporin-resistant Enterobacteriaceae in Argentina

Directory of Open Access Journals (Sweden)

Giovanna Rincon Cruz

2013-11-01

Full Text Available High quinolone resistance rates were observed among oxyiminocephalosporin-resistant enterobacteria. In the present study, we searched for the prevalence of plasmid-mediated quinolone resistance (PMQR genes within the 55 oxyiminocephalosporin-resistant enterobacteria collected in a previous survey. The main PMQR determinants were aac(6'-Ib-cr and qnrB, which had prevalence rates of 42.4% and 33.3%, respectively. The aac(6'-Ib-cr gene was more frequently found in CTX-M-15-producing isolates, while qnrB was homogeneously distributed among all CTX-M producers.

Determination of internal series resistance of PV devices: repeatability and uncertainty

International Nuclear Information System (INIS)

Trentadue, Germana; Pavanello, Diego; Salis, Elena; Field, Mike; Müllejans, Harald

2016-01-01

The calibration of photovoltaic devices requires the measurement of their current–voltage characteristics at standard test conditions (STC). As the latter can only be reached approximately, a curve translation is necessary, requiring among others the internal series resistance of the photovoltaic device as an input parameter. Therefore accurate and reliable determination of the series resistance is important in measurement and test laboratories. This work follows standard IEC 60891 ed 2 (2009) for the determination of the internal series resistance and investigates repeatability and uncertainty of the result in three aspects for a number of typical photovoltaic technologies. Firstly the effect of varying device temperature on the determined series resistance is determined experimentally and compared to a theoretical derivation showing agreement. It is found that the series resistance can be determined with an uncertainty of better than 5% if the device temperature is stable within  ±0.1 °C, whereas the temperature range of  ±2 °C allowed by the standard leads to much larger variations. Secondly the repeatability of the series resistance determination with respect to noise in current–voltage measurement is examined yielding typical values of  ±5%. Thirdly the determination of the series resistance using three different experimental set-ups (solar simulators) shows agreement on the level of  ±5% for crystalline Silicon photovoltaic devices and deviations up to 15% for thin-film devices. It is concluded that the internal series resistance of photovoltaic devices could be determined with an uncertainty of better than 10%. The influence of this uncertainty in series resistance on the electrical performance parameters of photovoltaic devices was estimated and showed a contribution of 0.05% for open-circuit voltage and 0.1% for maximum power. Furthermore it is concluded that the range of device temperatures allowed during determination of series

Crack resistance curves determination of tube cladding material

Energy Technology Data Exchange (ETDEWEB)

Bertsch, J. [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)]. E-mail: johannes.bertsch@psi.ch; Hoffelner, W. [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

2006-06-30

Zirconium based alloys have been in use as fuel cladding material in light water reactors since many years. As claddings change their mechanical properties during service, it is essential for the assessment of mechanical integrity to provide parameters for potential rupture behaviour. Usually, fracture mechanics parameters like the fracture toughness K {sub IC} or, for high plastic strains, the J-integral based elastic-plastic fracture toughness J {sub IC} are employed. In claddings with a very small wall thickness the determination of toughness needs the extension of the J-concept beyond limits of standards. In the paper a new method based on the traditional J approach is presented. Crack resistance curves (J-R curves) were created for unirradiated thin walled Zircaloy-4 and aluminium cladding tube pieces at room temperature using the single sample method. The procedure of creating sharp fatigue starter cracks with respect to optical recording was optimized. It is shown that the chosen test method is appropriate for the determination of complete J-R curves including the values J {sub 0.2} (J at 0.2 mm crack length), J {sub m} (J corresponding to the maximum load) and the slope of the curve.

Genome-wide identification of antimicrobial intrinsic resistance determinants in Staphylococcus aureus

Directory of Open Access Journals (Sweden)

Martin Vestergaard

2016-12-01

Full Text Available The emergence of antimicrobial resistance severely threatens our ability to treat bacterial infections. While acquired resistance has received considerable attention, relatively little is known of intrinsic resistance that allows bacteria to naturally withstand antimicrobials. Gene products that confer intrinsic resistance to antimicrobial agents may be explored for alternative antimicrobial therapies, by potentiating the efficacy of existing antimicrobials. In this study, we identified the intrinsic resistome to a broad spectrum of antimicrobials in the human pathogen, Staphylococcus aureus. We screened the Nebraska Transposon Mutant Library of 1920 single-gene inactivations in S. aureus strain JE2, for increased susceptibility to the anti-staphylococcal antimicrobials (ciprofloxacin, oxacillin, linezolid, fosfomycin, daptomycin, mupirocin, vancomycin and gentamicin. 68 mutants were confirmed by E-test to display at least two-fold increased susceptibility to one or more antimicrobial agents. The majority of the identified genes have not previously been associated with antimicrobial susceptibility in S. aureus. For example, inactivation of genes encoding for subunits of the ATP synthase, atpA, atpB, atpG and atpH, reduced the minimum inhibitory concentration (MIC of gentamicin 16-fold. To elucidate the potential of the screen, we examined treatment efficacy in the Galleria mellonella infection model. Gentamicin efficacy was significantly improved, when treating larvae infected with the atpA mutant compared to wild type cells with gentamicin at a clinically relevant concentration. Our results demonstrate that many gene products contribute to the intrinsic antimicrobial resistance of S. aureus. Knowledge of these intrinsic resistance determinants provides alternative targets for compounds that may potentiate the efficacy of existing antimicrobial agents against this important pathogen.

A single exposure to a sublethal pediocin concentration initiates a resistance-associated temporal cell envelope and general stress response in Listeria monocytogenes

DEFF Research Database (Denmark)

Laursen, Martin Frederik; Bahl, Martin Iain; Licht, Tine Rask

2015-01-01

was to determine if exposure to sublethal concentrations of pediocin-containing Lactobacillus plantarum WHE 92 supernatant could prime L. monocytogenes for resistance. By transcriptomic analysis, we found two, 55 and 539 genes differentially expressed after 10, 60 and 180 min of exposure to L. plantarum WHE 92...... resistant than wild types to L. plantarum WHE 92 supernatant. LisRK, SigB and SigL regulation and genes associated with resistance are involved in the temporal adaptive response to pediocin and all three regulatory systems affect pediocin resistance. Thus, a single exposure to a sublethal pediocin...

Magnon contribution to electrical resistance of gadolinium-dysprosium alloy single crystals

International Nuclear Information System (INIS)

Nikitin, S.A.; Slobodchikov, S.S.; Solomkin, I.K.

1978-01-01

The magnon, phonon and interelectron collision contributions to the electric resistance of single crystals of gadolinium-dysprosium alloys were quantified. A relationship was found to exist between the electric resistance and the variation of the topology of the Fermi surface on melting of gadolinium with dysprosium. It was found that gadolinium-dysprosium alloys, which have no helicoidal magnetic structure in magnetically ordered state, feature a spin-spin helicoidal-type correlations in the paramagnetic field

Performance of low-resistivity single and dual-gap RPCs for LHCb

CERN Document Server

Adinolfi, M; Messi, R; Pacciani, L; Paoluzi, L; Santovetti, E

2000-01-01

Resistive plate chambers (RPC) are strong candidates for the outer regions of the LHCb muon detector. We have tested single-gap and dual-gap detectors built with low-resistivity phenolic plates ( rho =9*10/sup 9/ Omega cm) and operated in avalanche mode. Measurements have been performed over a wide range of beam intensities and on the GIF at CERN. The results are presented and discussed, with special emphasis on the detection efficiency. (6 refs).

A novel fusidic acid resistance determinant, fusF, in Staphylococcus cohnii.

Science.gov (United States)

Chen, Hsiao-Jan; Hung, Wei-Chun; Lin, Yu-Tzu; Tsai, Jui-Chang; Chiu, Hao-Chieh; Hsueh, Po-Ren; Teng, Lee-Jene

2015-02-01

To determine MICs of fusidic acid for and identify genetic determinants of resistance in Staphylococcus cohnii isolates. Susceptibility to fusidic acid was determined by the standard agar dilution method in 24 S. cohnii subsp. urealyticus clinical isolates, 7 S. cohnii subsp. cohnii clinical isolates and 2 reference strains. Sequencing of a novel resistance determinant, fusF, and its flanking regions was performed by long and accurate PCR and inverse PCR. To evaluate the function of fusF, the MIC of fusidic acid was determined for recombinant Staphylococcus aureus carrying a plasmid expressing fusF. A total of 25 S. cohnii subsp. urealyticus (24 clinical isolates and 1 reference strain) and 2 S. cohnii subsp. cohnii displayed low-level resistance to fusidic acid (MICs 2-16 mg/L). Sequencing of a 4259 bp fragment from S. cohnii subsp. urealyticus ATCC 49330 revealed a novel resistance gene, designated fusF, which displayed 70.5% nucleotide and 67.3% amino acid identity to fusD. Expression of fusF in S. aureus confers resistance to fusidic acid. A novel FusB-family gene, fusF, was identified as a major resistance determinant in S. cohnii clinical isolates resistant to fusidic acid. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Determination of the Drag Resistance Coefficients of Different Vehicles

Science.gov (United States)

Fahsl, Christoph; Vogt, Patrik

2018-01-01

While it has been demonstrated how air resistance could be analyzed by using mobile devices, this paper demonstrates a method of how to determine the drag resistance coefficient "c" of a commercial automobile by using the acceleration sensor of a smartphone or tablet. In an academic context, the drag resistance is often mentioned, but…

Autosomal male determination in a spinosad-resistant housefly strain from Denmark

DEFF Research Database (Denmark)

Højland, Dorte H; Scott, Jeffrey G; Vagn Jensen, Karl-Martin

2014-01-01

males in this strain. The factor responsible for spinosad resistance in the strain is unknown, but previous studies suggest a role of cytochrome P450s for detoxification of spinosad. Sex determination in the housefly is controlled by a male-determining factor (M), either located on the Y chromosome......BACKGROUND The housefly, Musca domestica L., is a global pest and has developed resistance to most insecticides applied for its control. The insecticide spinosad plays an important role in housefly control. Females of the Danish housefly strain 791spin are threefold more resistant to spinosad than...... of resistance to spinosad. Sex determination in 791spin is due to a male factor on autosome 3. CONCLUSIONS The most likely explanation for the differentiation of spinosad resistance between males and females is a recessive spinosad resistance factor on autosome III. © 2013 Society of Chemical Industry...

Antimicrobial susceptibility and tetracycline resistance determinant genotyping of Gallibacterium anatis

DEFF Research Database (Denmark)

Bojesen, Anders M.; Vazquez, Maria E.; Bager, Ragnhild J.

2011-01-01

no determinant was identified.This is the first study to determine the antimicrobial susceptibility of Gallibacterium anatis by MIC revealing that multidrug resistance is very common among G. anatis field isolates. tet(B) was by far the most common determinant identified but future work should aim at identifying......The present investigation was undertaken to assess the antimicrobial susceptibility of a collection of 58 Gallibacterium isolates. All strains were tested by the broth dilution method using the veterinary fastidious medium. A total of 46 field strains were tested, whereof 23 were clinical isolates....... Multidrug resistance (resistance towards≥three drugs) was observed for 65% of the field strains and only two strains were susceptible to all compounds. Most prominently, resistance to tetracycline and sulfamethoxazole was observed in 92% and 97% of the field strains, respectively. For comparison...

30 CFR 27.41 - Test to determine resistance to moisture.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Test to determine resistance to moisture. 27.41... determine resistance to moisture. Components, subassemblies, or assemblies, the normal functioning of which might be affected by moisture, shall be tested in atmospheres of high relative humidity (80 percent or...

Determination of Flow Resistance Coefficient for Vegetation in Open Channel: Laboratory study

Science.gov (United States)

Aliza Ahmad, Noor; Ali, ZarinaMd; Arish, Nur Aini Mohd; Munirah Mat Daud, Azra; Fatin Amirah Alias, Nur

2018-04-01

This study focused on determination of flow resistances coefficient for grass in an open channel. Laboratory works were conducted to examine the effects of varying of roughness elements on the flume to determine flow resistance coefficient and also to determine the optimum flow resistance with five different flow rate, Q. Laboratory study with two type of vegetation which are Cow Grass and Pearl Grass were implementing to the bed of a flume. The roughness coefficient, n value is determine using Manning’s equation while Soil Conservation Services (SCS) method was used to determine the surface resistance. From the experiment, the flow resistance coefficient for Cow Grass in range 0.0008 - 0.0039 while Pearl Grass value for the flow resistance coefficient are in between 0.0013 - 0.0054. As a conclusion the vegetation roughness value in open channel are depends on density, distribution type of vegetation used and physical characteristic of the vegetation itself

A single point mutation in Tomato spotted wilt virus NSs protein is sufficient to overcome Tsw-gene-mediated resistance in pepper.

Science.gov (United States)

Almási, Asztéria; Nemes, Katalin; Csömör, Zsófia; Tóbiás, István; Palkovics, László; Salánki, Katalin

2017-06-01

The nonstructural protein (NSs) of Tomato spotted wilt virus (TSWV) was previously identified as an avirulence determinant for Tsw-based resistance on pepper. The NSs of wild-type (WT) and resistance-breaking (RB) TSWV strains isolated in Hungary had only two amino acid substitutions (104, 461). We have analysed the ability of the NSs and their point mutant variants to trigger Tsw-mediated hypersensitive responses and RNA silencing suppressor (RSS) activity in patch assays. We identified a single amino acid change at position 104 (T-A) that was responsible for the necrosis induction or loss, while a significant difference was not detected in the RSS activity of the two parental strains. We have successfully complemented the infection of the WT strain on resistant pepper cultivar with the infectious S RNA transcript of the RB strain and the WT-T104A point mutant. Our work provides direct evidence that a single amino acid change can induce an RB phenotype.

Antimicrobial resistance and resistance gene determinants in clinical Escherichia coli from different animal species in Switzerland.

Science.gov (United States)

Lanz, Roland; Kuhnert, Peter; Boerlin, Patrick

2003-01-02

Antimicrobial susceptibility testing was performed on a total of 581 clinical Escherichia coli isolates from diarrhea and edema disease in pigs, from acute mastitis in dairy cattle, from urinary tract infections in dogs and cats, and from septicemia in laying hens collected in Switzerland between 1999 and 2001. Among the 16 antimicrobial agents tested, resistance was most frequent for sulfonamides, tetracycline, and streptomycin. Isolates from swine presented significantly more resistance than those from the other animal species. The distribution of the resistance determinants for sulfonamides, tetracycline, and streptomycin was assessed by hybridization and PCR in resistant isolates. Significant differences in the distribution of resistance determinants for tetracycline (tetA, tetB) and sulfonamides (sulII) were observed between the isolates from swine and those from the other species. Resistance to sulfonamides could not be explained by known resistance mechanisms in more than a quarter of the sulfonamide-resistant and sulfonamide-intermediate isolates from swine, dogs and cats. This finding suggests that one or several new resistance mechanisms for sulfonamides may be widespread among E. coli isolates from these animal species. The integrase gene (intI) from class I integrons was detected in a large proportion of resistant isolates in association with the sulI and aadA genes, thus demonstrating the importance of integrons in the epidemiology of resistance in clinical E. coli isolates from animals.

Determination of electrical resistivity of dry coke beds

Energy Technology Data Exchange (ETDEWEB)

Eidem, P.A.; Tangstad, M.; Bakken, J.A. [NTNU, Trondheim (Norway)

2008-02-15

The electrical resistivity of the coke bed is of great importance when producing FeMn, SiMn, and FeCr in a submerged arc furnace. In these processes, a coke bed is situated below and around the electrode tip and consists of metallurgical coke, slag, gas, and metal droplets. Since the basic mechanisms determining the electrical resistivity of a coke bed is not yet fully understood, this investigation is focused on the resistivity of dry coke beds consisting of different carbonaceous materials, i.e., coke beds containing no slag or metal. A method that reliably compares the electrical bulk resistivity of different metallurgical cokes at 1500{sup o} C to 1600{sup o}C is developed. The apparatus is dimensioned for industrial sized materials, and the electrical resistivity of anthracite, charcoal, petroleum coke, and metallurgical coke has been measured. The resistivity at high temperatures of the Magnitogorsk coke, which has the highest resistivity of the metallurgical cokes investigated, is twice the resistivity of the Corus coke, which has the lowest electrical resistivity. Zdzieszowice and SSAB coke sort in between with decreasing resistivities in the respective order. The electrical resistivity of anthracite, charcoal, and petroleum coke is generally higher than the resistivity of the metallurgical cokes, ranging from about two to about eight times the resistivity of the Corus coke at 1450{sup o}C. The general trend is that the bulk resistivity of carbon materials decreases with increasing temperature and increasing particle size.

Bias voltage induced resistance switching effect in single-molecule magnets’ tunneling junction

Science.gov (United States)

Zhang, Zhengzhong; Jiang, Liang

2014-09-01

An electric-pulse-induced reversible resistance change effect in a molecular magnetic tunneling junction, consisting of a single-molecule magnet (SMM) sandwiched in one nonmagnetic and one ferromagnetic electrode, is theoretically investigated. By applying a time-varying bias voltage, the SMM's spin orientation can be manipulated with large bias voltage pulses. Moreover, the different magnetic configuration at high-resistance/low-resistance states can be ‘read out’ by utilizing relative low bias voltage. This device scheme can be implemented with current technologies (Khajetoorians et al 2013 Science 339 55) and has potential application in molecular spintronics and high-density nonvolatile memory devices.

Bias voltage induced resistance switching effect in single-molecule magnets' tunneling junction.

Science.gov (United States)

Zhang, Zhengzhong; Jiang, Liang

2014-09-12

An electric-pulse-induced reversible resistance change effect in a molecular magnetic tunneling junction, consisting of a single-molecule magnet (SMM) sandwiched in one nonmagnetic and one ferromagnetic electrode, is theoretically investigated. By applying a time-varying bias voltage, the SMM's spin orientation can be manipulated with large bias voltage pulses. Moreover, the different magnetic configuration at high-resistance/low-resistance states can be 'read out' by utilizing relative low bias voltage. This device scheme can be implemented with current technologies (Khajetoorians et al 2013 Science 339 55) and has potential application in molecular spintronics and high-density nonvolatile memory devices.

Determination of rolling resistance coefficient based on normal tyre stiffness

Science.gov (United States)

Rykov, S. P.; Tarasuyk, V. N.; Koval, V. S.; Ovchinnikova, N. I.; Fedotov, A. I.; Fedotov, K. V.

2018-03-01

The purpose of the article is to develop analytical dependence of wheel rolling resistance coefficient based on the mathematical description of normal tyre stiffness. The article uses the methods of non-holonomic mechanics and plane section methods. The article shows that the abscissa of gravity center of tyre stiffness expansion by the length of the contact area is the shift of normal road response. It can be used for determining rolling resistance coefficient. When determining rolling resistance coefficient using ellipsis and power function equations, one can reduce labor costs for testing and increase assessment accuracy.

Antimicrobial resistance determinants among anaerobic bacteria isolated from footrot.

Science.gov (United States)

Lorenzo, María; García, Nuria; Ayala, Juan Alfonso; Vadillo, Santiago; Píriz, Segundo; Quesada, Alberto

2012-05-25

Antibiotic resistance has been evaluated among 36 Gram negative and anaerobic bacilli (10 Bacteroides, 11 Prevotella, 7 Porphyromonas and 8 Fusobacterium strains) isolated from clinical cases of caprine and ovine footrot (necrotic pododermatitis). The initial analysis on this bacterial consortium evaluates the relationships existing among antimicrobial resistance determinants, phenotype expression and mobilization potential. The Bacteroides strains were generally resistant to penicillins, first-generation cephalosporins, tetracycline and erythromycin, and expressed low level of β-lactamase activity. The main determinants found among the Bacteroides strains were cepA and tetQ genes, conferring resistance to β-lactams and tetracycline, respectively. A general susceptibility to β-lactams was shown for most Prevotella, Porphyromonas and Fusobacterium strains, where none of the β-lactamase genes described in Bacteroides was detected. Resistance to tetracycline and/or erythromycin was found among the three bacterial groups. Although tetQ genes were detected for several Prevotella and Porphyromonas strains, a unique ermF positive was revealed among Prevotella strains. The expression of resistance markers was not related with the polymorphism of their coding sequences. However, the finding of sequence signatures for conjugative transposons in the vicinities of tetQ and ermF suggests a mobilization potential that might have contributed to the spread of antimicrobial resistance genes. Copyright © 2011 Elsevier B.V. All rights reserved.

A Laboratory Exercise in Physics: Determining the Resistance of Single Resistors and Series and Parallel Combinations of Resistance.

Science.gov (United States)

Schlenker, Richard M.

Presented is a secondary level physics unit which introduces students to electrical resistance in series and parallel combinations, use of the voltmeter and ammeter, wiring simple circuits, and writing scientific reports. (SL)

Genetic determinants of heat resistance in Escherichia coli

Directory of Open Access Journals (Sweden)

Ryan eMercer

2015-09-01

Full Text Available Escherichia coli AW1.7 is a heat resistant food isolate and the occurrence of pathogenic strains with comparable heat resistance may pose a risk to food safety. To identify the genetic determinants of heat resistance, 29 strains of E. coli that differed in their of heat resistance were analyzed by comparative genomics. Strains were classified as highly heat resistant strains, exhibiting a D60-value of more than 6 min; moderately heat resistant strains, exhibiting a D60-value of more than 1 min; or as heat sensitive. A ~14 kb genomic island containing 16 predicted open reading frames encoding putative heat shock proteins and proteases was identified only in highly heat resistant strains. The genomic island was termed the locus of heat resistance (LHR. This putative operon is flanked by mobile elements and possesses >99% sequence identity to genomic islands contributing to heat resistance in Cronobacter sakazakii and Klebsiella pneumoniae. An additional 41 LHR sequences with >87% sequence identity were identified in 11 different species of β- and γ-proteobacteria. Cloning of the full length LHR conferred high heat resistance to the heat sensitive E. coli AW1.7ΔpHR1 and DH5α. The presence of the LHR correlates perfectly to heat resistance in several species of Enterobacteriaceae and occurs at a frequency of 2% of all E. coli genomes, including pathogenic strains. This study suggests the LHR has been laterally exchanged among the β- and γ-proteobacteria and is a reliable indicator of high heat resistance in E. coli.

Nanosecond X-ray detector based on high resistivity ZnO single crystal semiconductor

Energy Technology Data Exchange (ETDEWEB)

Zhao, Xiaolong; He, Yongning, E-mail: yongning@mail.xjtu.edu.cn; Peng, Wenbo; Huang, Zhiyong; Qi, Xiaomeng; Pan, Zijian; Zhang, Wenting [School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Chen, Liang; Liu, Jinliang; Zhang, Zhongbing; Ouyang, Xiaoping [Radiation Detection Research Center, Northwest Institute of Nuclear Technology, Xi' an 710024 (China)

2016-04-25

The pulse radiation detectors are sorely needed in the fields of nuclear reaction monitoring, material analysis, astronomy study, spacecraft navigation, and space communication. In this work, we demonstrate a nanosecond X-ray detector based on ZnO single crystal semiconductor, which emerges as a promising compound-semiconductor radiation detection material for its high radiation tolerance and advanced large-size bulk crystal growth technique. The resistivity of the ZnO single crystal is as high as 10{sup 13} Ω cm due to the compensation of the donor defects (V{sub O}) and acceptor defects (V{sub Zn} and O{sub i}) after high temperature annealing in oxygen. The photoconductive X-ray detector was fabricated using the high resistivity ZnO single crystal. The rise time and fall time of the detector to a 10 ps pulse electron beam are 0.8 ns and 3.3 ns, respectively, indicating great potential for ultrafast X-ray detection applications.

Determination of anthelmintic resistance in goats and sheep using ...

African Journals Online (AJOL)

Nematode parasites are known to pose a challenge to small ruminant production in Tanzania due to their fast development of resistance to the commonly used anthelmintics. The objective of this study was to determine the resistance of anthelmintics in small ruminants. A total of 30 sheep and 30 goats aged between 6 and ...

Determination of ductile tearing resistance J-R curves in welded joints; Determination de courbes de resistance a la dechirure ductile dans les joints soudes

Energy Technology Data Exchange (ETDEWEB)

Gilles, Ph.; Ould, P. [AREVA NP, Tour AREVA, 92086 Paris La Defense (France); Marie, St. [CEA Saclay, DM2S, 91191 Gif sur Yvette Cedex (France)

2010-05-15

The ductile tearing resistance of steels is generally characterized in terms of resistance curves giving the increase of a resistance parameter such as the crack driving force J or a crack opening displacement as a function of the crack extension {Delta}a. Welded joints are often the weakest part of structures because of greater risk of defects, heterogeneity of the microstructure of the weld, strain concentration along mismatched interfaces. This paper recalls the transferability issues common to all integrity assessments based on tearing resistance curves and points out the difficulties of characterization specific to welds. Several recommendations are proposed for the experimental determination of tearing resistance of welded joints. (authors)

Prevalence and determinants of resistant hypertension among ...

African Journals Online (AJOL)

Tropical Journal of Pharmaceutical Research ... Prevalence and determinants of resistant hypertension among hypertensive patients attending a cardiology clinic in ... Obese patients and those suffering from diabetes mellitus, ischemic heart ... By Country · List All Titles · Free To Read Titles This Journal is Open Access.

Fire resistance of single pitched-roof steel portal frame

Directory of Open Access Journals (Sweden)

J. J. Ferrán Gozálvez

2017-03-01

Full Text Available The standard procedure of structural fire design is based on the simplified analysis of single members. This method leads to conservative results in the case of structures able to redistribution of forces. The failure mechanism affecting both life safety and fire propagation is unknown. This work proposes a methodology for the advanced fire calculation of single pitched-roof portal frame for an agroindustrial building according to the Spanish Specifications with the structural software SAP2000. A non-linear dynamic and plastic, geometric (P-Delta and large-displacements calculation method has been developed. The different failure mechanisms and their influence are studied in terms of fire time resistance, human hazard and good safety. Also, parametric analyses were conducted: load level, rotational stiffness of the base and finally, support fire protection.

Determining the resistance of X-pinch plasma

International Nuclear Information System (INIS)

Zhao Shen; Zhu Xin-Lei; Zhang Ran; Luo Hai-Yun; Zou Xiao-Bing; Wang Xin-Xin; Xue Chuang; Ning Cheng; Ding Ning; Shu Xiao-Jian

2013-01-01

The current and the voltage of an X-pinch were measured. The inductance of the X-pinch was assumed to be a constant and estimated by the calculation of the magnetic field based on the well-known Biot—Savart's Law. The voltage of the inductance was calculated with L · di/dt and subtracted from the measured voltage of the X-pinch. Then, the resistance of the X-pinch was determined and the following results were obtained. At the start of the current flow the resistance of the exploding wires is several tens of Ohms, one order of magnitude, higher than the metallic resistance of the wires at room temperature, and then it falls quickly to about 1 Ω, which reflects the physical processes occurring in the electrically exploding wires, i.e., a current transition from the highly resistive wire core to the highly conductive plasma. It was shown that the inductive contribution to the voltage of the X-pinch is less than the resistive contribution. For the wires we used, the wires' material and diameter have no strong influence on the resistance of the X-pinch, which may be explained by the fact that the current flows through the plasma rather than through the metallic wire itself. As a result, the current is almost equally divided between two parallel X-pinches even though the diameter and material of the wires used for these two X-pinches are significantly different. (physics of gases, plasmas, and electric discharges)

Electrical resistivity determination of subsurface layers, subsoil ...

African Journals Online (AJOL)

Electrical resistivity determination of subsurface layers, subsoil competence and soil corrosivity at and engineering site location in Akungba-Akoko, ... The study concluded that the characteristics of the earth materials in the site would be favourable to normal engineering structures/materials that may be located on it.

A Simple and Sensitive Plant-Based Western Corn Rootworm Bioassay Method for Resistance Determination and Event Selection.

Science.gov (United States)

Wen, Zhimou; Chen, Jeng Shong

2018-05-26

We report here a simple and sensitive plant-based western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), bioassay method that allows for examination of multiple parameters for both plants and insects in a single experimental setup within a short duration. For plants, injury to roots can be visually examined, fresh root weight can be measured, and expression of trait protein in plant roots can be analyzed. For insects, in addition to survival, larval growth and development can be evaluated in several aspects including body weight gain, body length, and head capsule width. We demonstrated using the method that eCry3.1Ab-expressing 5307 corn was very effective against western corn rootworm by eliciting high mortality and significantly inhibiting larval growth and development. We also validated that the method allowed determination of resistance in an eCry3.1Ab-resistant western corn rootworm strain. While data presented in this paper demonstrate the usefulness of the method for selection of events of protein traits and for determination of resistance in laboratory populations, we envision that the method can be applied in much broader applications.

[Loading and strength of single- and multi-unit fixed dental prostheses. 1. Retention and resistance

NARCIS (Netherlands)

Baat, C. de; Witter, D.J.; Meijers, C.C.A.J.; Vergoossen, E.L.; Creugers, N.H.J.

2014-01-01

The degree to which single- and multi-unit fixed dental prostheses are able to withstand loading forces is dependent, among other things, on the quality of their retention and resistance. The quality of the retention and resistance of the configuration of an abutment tooth prepared for a metal and

Antimicrobial Resistance of Hypervirulent Klebsiella pneumoniae: Epidemiology, Hypervirulence-Associated Determinants, and Resistance Mechanisms

Directory of Open Access Journals (Sweden)

Chang-Ro Lee

2017-11-01

Full Text Available Klebsiella pneumoniae is one of the most clinically relevant species in immunocompromised individuals responsible for community-acquired and nosocomial infections, including pneumonias, urinary tract infections, bacteremias, and liver abscesses. Since the mid-1980s, hypervirulent K. pneumoniae, generally associated with the hypermucoviscosity phenotype, has emerged as a clinically significant pathogen responsible for serious disseminated infections, such as pyogenic liver abscesses, osteomyelitis, and endophthalmitis, in a generally younger and healthier population. Hypervirulent K. pneumoniae infections were primarily found in East Asia and now are increasingly being reported worldwide. Although most hypervirulent K. pneumoniae isolates are antibiotic-susceptible, some isolates with combined virulence and resistance, such as the carbapenem-resistant hypervirulent K. pneumoniae isolates, are increasingly being detected. The combination of multidrug resistance and enhanced virulence has the potential to cause the next clinical crisis. To better understand the basic biology of hypervirulent K. pneumoniae, this review will provide a summarization and discussion focused on epidemiology, hypervirulence-associated factors, and antibiotic resistance mechanisms of such hypervirulent strains. Epidemiological analysis of recent clinical isolates in China warns the global dissemination of hypervirulent K. pneumoniae strains with extensive antibiotic resistance in the near future. Therefore, an immediate response to recognize the global dissemination of this hypervirulent strain with resistance determinants is an urgent priority.

Determination of the electrical resistivity of vertically aligned carbon nanotubes by scanning probe microscopy

Science.gov (United States)

Ageev, O. A.; Il'in, O. I.; Rubashkina, M. V.; Smirnov, V. A.; Fedotov, A. A.; Tsukanova, O. G.

2015-07-01

Techniques are developed to determine the resistance per unit length and the electrical resistivity of vertically aligned carbon nanotubes (VA CNTs) using atomic force microscopy (AFM) and scanning tunneling microscopy (STM). These techniques are used to study the resistance of VA CNTs. The resistance of an individual VA CNT calculated with the AFM-based technique is shown to be higher than the resistance of VA CNTs determined by the STM-based technique by a factor of 200, which is related to the influence of the resistance of the contact of an AFM probe to VA CNTs. The resistance per unit length and the electrical resistivity of an individual VA CNT 118 ± 39 nm in diameter and 2.23 ± 0.37 μm in height that are determined by the STM-based technique are 19.28 ± 3.08 kΩ/μm and 8.32 ± 3.18 × 10-4 Ω m, respectively. The STM-based technique developed to determine the resistance per unit length and the electrical resistivity of VA CNTs can be used to diagnose the electrical parameters of VA CNTs and to create VA CNT-based nanoelectronic elements.

Mini-Mu insertions in the tetracycline resistance determinant from Proteus mirabilis

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Magalhães V.D.

1997-01-01

Full Text Available The inducible tetracycline resistance determinant isolated from Proteus mirabilis cloned into the plasmid pACYC177 was mutagenized by insertion of a mini-Mu-lac phage in order to define the regions in the cloned sequences encoding the structural and regulatory proteins. Three different types of mutants were obtained: one lost the resistance phenotype and became Lac+; another expressed the resistance at lower levels and constitutively; the third was still dependent on induction but showed a lower minimal inhibitory concentration. The mutant phenotypes and the locations of the insertions indicate that the determinant is composed of a repressor gene and a structural gene which are not transcribed divergently as are other known tetracycline determinants isolated from Gram-negative bacteria

Determination of Ductile Tearing Resistance Curve in Weld Joints

International Nuclear Information System (INIS)

Marie, S.; Gilles, P.; Ould, P.

2010-01-01

Steels present in the ductile domain a tearing resistance which increase with the crack propagation up to the failure. This ductile tearing resistance is in general characterised with curves giving the variation of a global parameter (opening displacement at the crack tip delta, integral J) versus the crack extension Delta a. These global approaches depend more or less on the specimen geometry and on the type of the imposed loading. Local approaches based on the description of the ductile tearing mechanisms provide reliable solution to the transferability problem (from the lab specimen to the component) but are complex and costly to use and are not codified. These problems get worse in the case of a weld joint where no standard is available for the measurement of their ductile tearing resistance. But the welded joints are often the weak point of the structure because of greater risk of defects, the heterogeneity of the microstructure of the weld, deformation along the interface between two materials with different yield stress (mismatch).... After briefly recalling the problems of transferability of the ductile tearing resistance curves obtained on lab specimen to the case of components, this article identifies the factors complicating the determination of the toughness in the welded joints and gives recommendations for the experimental determination of ductile tearing resistance curves of welded joints

Preparation and oxidation resistance of single crystalline β-Zn{sub 4}Sb{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Liu, Hong-xia; Deng, Shu-ping [Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Yunnan Normal University, Kunming 650500 (China); Li, De-cong [Photoelectric Engineering College, Yunnan Open University, Kunming 650500 (China); Shen, Lan-xian; Cheng, Feng; Wang, Jin-song [Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Yunnan Normal University, Kunming 650500 (China); Deng, Shu-kang, E-mail: skdeng@126.com [Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Yunnan Normal University, Kunming 650500 (China)

2016-11-01

This study prepared a Zn-rich single crystal β-Zn{sub 4}Sb{sub 3} using a Sn flux method based on the stoichiometric ratios of Zn{sub 4.4}Sb{sub 3}Sn{sub 3}. The oxidation resistance of the sample was determined by exploring the effects of heat treatment in air on electrical transport properties and thermal stability, which is of practical importance in the application of the material at high temperatures. Results showed that the prepared sample possessed high electrical transport properties, with a high power factor of 1.67×10{sup −3} W m{sup −1} K{sup −2} at 563 K. The heat treatment in air weakened the electrical conductivity of the single crystalline β-Zn{sub 4}Sb{sub 3}, whereas the Seebeck coefficients were rarely independent of the annealing condition. Eventually, the power factor obtained after the first heating at 523 K for 4 h became comparable to that of the as-prepared sample, although it decreased after the second heating at 573 K for 5 h. Nevertheless, the single crystalline β-Zn{sub 4}Sb{sub 3} still possessed a good thermal stability after the heat treatment process.

Anomalous magnetotransport properties of high-quality single crystals of Weyl semimetal WTe2: Sign change of Hall resistivity

Science.gov (United States)

Jha, Rajveer; Higashinaka, Ryuji; Matsuda, Tatsuma D.; Ribeiro, Raquel A.; Aoki, Yuji

2018-05-01

We report on a systematic study of Hall effect using high quality single crystals of type-II Weyl semimetal WTe2 with the applied magnetic field B//c. The residual resistivity ratio of 1330 and the large magnetoresistance of 1.5 × 106 % in 9 T at 2 K, being in the highest class in the literature, attest to their high quality. Based on a simple two-carrier model, the densities (ne and nh) and mobilities (μe and μh) for electron and hole carriers have been uniquely determined combining both Hall- and electrical-resistivity data. The difference between ne and nh is 1% at 2 K, indicating that the system is in an compensated condition. The negative Hall resistivity growing rapidly below 20 K is due to a rapidly increasing μh/μe approaching one. Below 3 K in a low field region, we found the Hall resistivity becomes positive, reflecting that μh/μe finally exceeds one in this region. These anomalous behaviors of the carrier densities and mobilities might be associated with the existence of a Lifshitz transition and/or the spin texture on the Fermi surface.

Determination of resist parameters using the extended Nijboer-Zernike theory

NARCIS (Netherlands)

Dirksen, P.; Braat, J.; Janssen, A.J.E.M.; Leeuwestein, A.; Kwinten, H.; Van Steenwinckel, D.

2004-01-01

This study presents an experimental method to determine the resist parameters that are at the origin of a general blurring of the projected aerial image. The resist model includes the effects of diffusion in the horizontal plane and a second cause for image blur that originates from a stochastic

Determination of the drag resistance coefficients of different vehicles

Science.gov (United States)

Fahsl, Christoph; Vogt, Patrik

2018-05-01

While it has been demonstrated how air resistance could be analyzed by using mobile devices, this paper demonstrates a method of how to determine the drag resistance coefficient c of a commercial automobile by using the acceleration sensor of a smartphone or tablet. In an academic context, the drag resistance is often mentioned, but little attention is paid to quantitative measurements. This experiment was driven by the fact that this physical value is most certainly neglected because of its difficult measurability. In addition to that, this experiment gives insights on how the aerodynamic factor of an automobile affects the energy dissipation and thus how much power is required by automobile transportation.

Electrical resistivity monitoring of the single heater test in Yucca Mountain

International Nuclear Information System (INIS)

Ramirez, A.

1997-10-01

Of the several thermal, mechanical and hydrological measurements being used to monitor the rockmass response in the Single Heater Test, electrical resistance tomography (ERT) is being used to monitor the movement of liquid water with a special interest in the movement of condensate out of the system. Images of resistivity change were calculated using data collected before, during and after the heating episode. This report will concentrate on the results obtained after heating ceased; previous reports discuss the results obtained during the heating phase. The changes recovered show a region of increasing resistivity approximately centered around the heater as the rock mass cooled. The size of this region grows with time and the resistivity increases become stronger. The increases in resistivity are caused by both temperature and saturation changes. The Waxman Smits model has been used to calculate rock saturation after accounting for temperature effects. The saturation estimates suggest that during the heating phase, a region of drying forms around the heater. During the cooling phase, the dry region has remained relatively stable. Wetter rock regions which developed below the heater during the heating phase, are slowly becoming smaller in size during the cooling phase. The last set of images indicate that some rewetting of the dry zone may be occurring. The accuracy of the saturation estimates depends on several factors that are only partly understood

Resistive switching behavior in single crystal SrTiO{sub 3} annealed by laser

Energy Technology Data Exchange (ETDEWEB)

Pan, Xinqiang [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Shuai, Yao, E-mail: yshuai@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Wu, Chuangui, E-mail: cgwu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Luo, Wenbo [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Sun, Xiangyu [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Yuan, Ye; Zhou, Shengqiang [Helmholtz-Zentrum Dresden Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, D-01328 Dresden (Germany); Ou, Xin [State Key Laboratory of Functional Material for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Zhang, Wanli [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2016-12-15

Highlights: • Laser annealing was used to introduce oxygen vacancies into the single crystal SrTiO{sub 3}. • The effect of laser annealing with different fluence on the single crystal SrTiO{sub 3} was systematically studied. • The concentration of oxygen vacancies can be tuned by changing the fluence of laser. • Resistive switching behavior was observed in the sample with relatively high laser fluence after an electro-forming process. - Abstract: Single crystal SrTiO{sub 3} (STO) wafers were annealed by XeCl laser (λ = 308 nm) with different fluences of 0.4 J/cm{sup 2}, 0.6 J/cm{sup 2} and 0.8 J/cm{sup 2}, respectively. Ti/Pt electrodes were sputtered on the surface of STO wafer to form co-planar capacitor-like structures of Pt/Ti/STO/Ti/Pt. Current-Voltage measurements show that the leakage current is enhanced by increasing laser fluence. Resistive switching behavior is only observed in the sample annealed by laser with relatively high fluence after an electro-forming process. The X-ray photoelectron spectroscopy measurements indicate that the amount of oxygen vacancies increases with the increase of laser fluence. This work indicates resistive switching appears when enough oxygen vacancies are generated by the laser, which form conductive filaments under an external electric field.

A single bout of resistance exercise can enhance episodic memory performance.

Science.gov (United States)

Weinberg, Lisa; Hasni, Anita; Shinohara, Minoru; Duarte, Audrey

2014-11-01

Acute aerobic exercise can be beneficial to episodic memory. This benefit may occur because exercise produces a similar physiological response as physical stressors. When administered during consolidation, acute stress, both physical and psychological, consistently enhances episodic memory, particularly memory for emotional materials. Here we investigated whether a single bout of resistance exercise performed during consolidation can produce episodic memory benefits 48 h later. We used a one-leg knee extension/flexion task for the resistance exercise. To assess the physiological response to the exercise, we measured salivary alpha amylase (a biomarker of central norepinephrine), heart rate, and blood pressure. To test emotional episodic memory, we used a remember-know recognition memory paradigm with equal numbers of positive, negative, and neutral IAPS images as stimuli. The group that performed the exercise, the active group, had higher overall recognition accuracy than the group that did not exercise, the passive group. We found a robust effect of valence across groups, with better performance on emotional items as compared to neutral items and no difference between positive and negative items. This effect changed based on the physiological response to the exercise. Within the active group, participants with a high physiological response to the exercise were impaired for neutral items as compared to participants with a low physiological response to the exercise. Our results demonstrate that a single bout of resistance exercise performed during consolidation can enhance episodic memory and that the effect of valence on memory depends on the physiological response to the exercise. Copyright © 2014 Elsevier B.V. All rights reserved.

Significance of Coexisting Mutations on Determination of the Degree of Isoniazid Resistance in Mycobacterium tuberculosis Strains.

Science.gov (United States)

Karunaratne, Galbokka Hewage Roshanthi Eranga; Wijesundera, Sandhya Sulochana; Vidanagama, Dhammika; Adikaram, Chamila Priyangani; Perera, Jennifer

2018-04-23

The emergence and spread of drug-resistant tuberculosis (TB) pose a threat to TB control in Sri Lanka. Isoniazid (INH) is a key element of the first-line anti-TB treatment regimen. Resistance to INH is mainly associated with point mutations in katG, inhA, and ahpC genes. The objective of this study was to determine mutations of these three genes in INH-resistant Mycobacterium tuberculosis (MTb) strains in Sri Lanka. Complete nucleotide sequence of the three genes was amplified by polymerase chain reaction and subjected to DNA sequencing. Point mutations in the katG gene were identified in 93% isolates, of which the majority (78.6%) were at codon 315. Mutations at codons 212 and 293 of the katG gene have not been reported previously. Novel mutations were recognized in the promoter region of the inhA gene (C deletion at -34), fabG1 gene (codon 27), and ahpC gene (codon 39). Single S315T mutation in the katG gene led to a high level of resistance, while a low level of resistance with high frequency (41%) was observed when katG codon 315 coexisted with the mutation at codon 463. Since most of the observed mutations of all three genes coexisted with the katG315 mutation, screening of katG315 mutations will be a useful marker for molecular detection of INH resistance of MTb in Sri Lanka.

Transferable chloramphenicol resistance determinant in luminous Vibrio harveyi from penaeid shrimp Penaeus monodon larvae

Directory of Open Access Journals (Sweden)

Thangapalam Jawahar Abraham

2016-12-01

Full Text Available Antibiotic-resistant luminous Vibrio harveyi strains isolated from Penaeus monodon larvae were screened for the possession of transferable resistance determinants. All the strains were resistant to chloramphenicol and the determinant coding for chloramphenicol resistance was transferred to Escherichia coli at frequencies of 9.50x10-4 to 4.20x10-4. The results probably suggest the excessive use of chloramphenicol in shrimp hatcheries to combat luminous vibriosis.

Patterns of resistance and transgression in Eastern Indonesia: single women's practices of clandestine courtship and cohabitation.

Science.gov (United States)

Bennett, Linda Rae

2005-03-01

This paper explores how single women in the regional Indonesian city of Mataram express sexual desire in a social, cultural and political climate that idealizes the confinement of female sexuality within marriage. It is based on 21 months of ethnographic fieldwork conducted with single women, their families and health care providers. Success for young women in negotiating sexual desire is dependent upon their ability to maintain a faultless public reputation and mediate between their desires and those of men. Many single women find ways to pursue their desires by bending the rules of courtship conventions, performing sexual purity in public, while resisting from within the hegemonic sexual culture. However, women who visibly transgress dominant sexual ideals (and in doing so offend the status quo) are stigmatized and ostracized. Single women's practice of resistance and sexual transgression in premarital relationships are represented using the examples of pacaran backstreet (clandestine courtship) and cohabitation prior to marriage.

Performance of low resistivity single and dual-gap RPCs for LHCb

CERN Document Server

Adinolfi, M; Messi, R; Pacciani, L; Santovetti, E; Santovetti, Emanuele

1999-01-01

99-049 RPCs are strong candidates for the outer regions of the LHCb muon detector. We have tested single-gap and dual-gap detectors built with low-resistivity phenolic plates (ro = 9 x 10^9 microcm) and operated in avalanche mode. Measurements have been performed over a wide range of beam intensities and on the GIF at CERN. The results are presented and discussed, with special emphasis on the detection efficiency.

Genome-Wide Identification of Antimicrobial Intrinsic Resistance Determinants in Staphylococcus aureus

DEFF Research Database (Denmark)

Vestergaard, Martin; Leng, Bingfeng; Haaber, Jakob

2016-01-01

The emergence of antimicrobial resistance severely threatens our ability to treat bacterial infections. While acquired resistance has received considerable attention, relatively little is known of intrinsic resistance that allows bacteria to naturally withstand antimicrobials. Gene products...... that confer intrinsic resistance to antimicrobial agents may be explored for alternative antimicrobial therapies, by potentiating the efficacy of existing antimicrobials. In this study, we identified the intrinsic resistome to a broad spectrum of antimicrobials in the human pathogen, Staphylococcus aureus. We...... with the atpA mutant compared to wild type cells with gentamicin at a clinically relevant concentration. Our results demonstrate that many gene products contribute to the intrinsic antimicrobial resistance of S. aureus. Knowledge of these intrinsic resistance determinants provides alternative targets...

Image charge effects in single-molecule junctions: Breaking of symmetries and negative-differential resistance in a benzene single-electron transistor

DEFF Research Database (Denmark)

Kaasbjerg, Kristen; Flensberg, K.

2011-01-01

and molecular symmetries remain unclear. Using a theoretical framework developed for semiconductor-nanostructure-based single-electron transistors (SETs), we demonstrate that the image charge interaction breaks the molecular symmetries in a benzene-based single-molecule transistor operating in the Coulomb...... blockade regime. This results in the appearance of a so-called blocking state, which gives rise to negative-differential resistance (NDR). We show that the appearance of NDR and its magnitude in the symmetry-broken benzene SET depends in a complicated way on the interplay between the many-body matrix...

Using Resistivity Measurements to Determine Anisotropy in Soil and Weathered Rock

Directory of Open Access Journals (Sweden)

S. Soto-Caban

2013-08-01

Full Text Available This study uses electrical resistivity measurements of soils and weathered rock to perform a fast and reliable evaluation of field anisotropy. Two test sites at New Concord, Ohio were used for the study. These sites are characterized by different landform and slightly east dipping limestone and siltstone formations of Pennsylvanian age. The measured resistivity ranged from 19 Ω∙m to 100 ��∙m, and varied with depth, landform, and season. The anisotropy was determined by a comparison of resistance values along the directions of strike and the dip. Measurements showed that the orientation of electrical anisotropy in the shallow ground may vary due to fluid connection, which is determined by the pore geometry in soil and rock, as well as by the direction of fluid movement. Results from this study indicated that a portable electrical resistivity meter is sensitive and reliable enough to be used for shallow ground fluid monitoring.

Skid resistance determination for pavement management and wet-weather road safety

Directory of Open Access Journals (Sweden)

T.F. Fwa

2017-09-01

Full Text Available Road accidents during wet weather have been a topic of major concern of road engineers in regions of wet-tropical climate and in other parts of the world during the wet season of the year. Road safety studies indicate that approximately 20% of all road accidents occurred during wet weather, and that the skid resistance of wet pavements have a major influence on the occurrences of wet-weather accidents. Monitoring of wet pavement skid resistance has been an integral part of a typical pavement management system. However, because of the lack of prediction capability of pavement skid resistance under various rainfall intensities, the minimum skid resistance threshold for safe wet-weather driving has been specified by highway agencies based on either engineering judgement or past experience. It is shown in this paper that the single-point minimum skid resistance threshold is inadequate to offer a complete description of the skid resistance performance of the pavement sections in question for effective management of a road network. It is unable to assess the risk involved in an actual wet-weather condition where the pavement surface water-film thickness and vehicle speed are different from standard test conditions. This limitation of the current system of specifying a minimum skid resistance threshold can be overcome by adopting a theoretically sound approach to represent pavement skid resistance under different conditions of water-film thickness and vehicle speed. This paper describes the theoretical basis of the approach and the development of a mechanistically derived three-dimensional finite-element skid resistance simulation model to predict skid resistance. The application of the proposed approach and the skid resistance prediction procedure in pavement management system and wet-weather driving safety assessment is presented.

Prevalence of Genotypes That Determine Resistance of Staphylococci to Macrolides and Lincosamides in Serbia

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Milena Mišić

2017-08-01

Full Text Available Macrolides, lincosamides, and streptogramins (MLS resistance genes are responsible for resistance to these antibiotics in Staphylococcus infections. The purpose of the study was to analyze the distribution of the MLS resistance genes in community- and hospital-acquired Staphylococcus isolates. The MLS resistance phenotypes [constitutive resistance to macrolide–lincosamide–streptogramin B (cMLSb, inducible resistance to macrolide–lincosamide–streptogramin B (iMLSb, resistance to macrolide/macrolide–streptogramin B (M/MSb, and resistance to lincosamide–streptogramin A/streptogramin B (LSa/b] were determined by double-disc diffusion method. The presence of the MLS resistance genes (ermA, ermB, ermC, msrA/B, lnuA, lnuB, and lsaA were determined by end-point polymerase chain reaction in 179 isolates of staphylococci collected during 1-year period at the Center for Microbiology of Public Health Institute in Vranje. The most frequent MLS phenotype among staphylococcal isolates, both community-acquired and hospital-acquired, was iMLSb (33.4%. The second most frequent was M/MSb (17.6% with statistically significantly higher number of hospital-acquired staphylococcal isolates (p < 0.05. MLS resistance was mostly determined by the presence of msrA/B (35.0% and ermC (20.8% genes. Examined phenotypes were mostly determined by the presence of one gene, especially by msrA/B (26.3% and ermC (14.5%, but 15.6% was determined by a combination of two or more genes. M/MSb phenotype was the most frequently encoded by msrA/B (95.6% gene, LSa/b phenotype by lnuA (56.3% gene, and iMLSb phenotype by ermC (29.4% and ermA (25.5% genes. Although cMLSb phenotype was mostly determined by the presence of ermC (28.9%, combinations of two or more genes have been present too. This pattern was particularly recorded in methicillin-resistant Staphylococcus aureus (MRSA (58.3% and methicillin-resistant coagulase-negative staphylococci (MRCNS (90.9% isolates with c

Single-cell multiple gene expression analysis based on single-molecule-detection microarray assay for multi-DNA determination

Energy Technology Data Exchange (ETDEWEB)

Li, Lu [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Wang, Xianwei [School of Life Sciences, Shandong University, Jinan 250100 (China); Zhang, Xiaoli [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Wang, Jinxing [School of Life Sciences, Shandong University, Jinan 250100 (China); Jin, Wenrui, E-mail: jwr@sdu.edu.cn [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

2015-01-07

Highlights: • A single-molecule-detection (SMD) microarray for 10 samples is fabricated. • The based-SMD microarray assay (SMA) can determine 8 DNAs for each sample. • The limit of detection of SMA is as low as 1.3 × 10{sup −16} mol L{sup −1}. • The SMA can be applied in single-cell multiple gene expression analysis. - Abstract: We report a novel ultra-sensitive and high-selective single-molecule-detection microarray assay (SMA) for multiple DNA determination. In the SMA, a capture DNA (DNAc) microarray consisting of 10 subarrays with 9 spots for each subarray is fabricated on a silanized glass coverslip as the substrate. On the subarrays, the spot-to-spot spacing is 500 μm and each spot has a diameter of ∼300 μm. The sequence of the DNAcs on the 9 spots of a subarray is different, to determine 8 types of target DNAs (DNAts). Thus, 8 types of DNAts are captured to their complementary DNAcs at 8 spots of a subarray, respectively, and then labeled with quantum dots (QDs) attached to 8 types of detection DNAs (DNAds) with different sequences. The ninth spot is used to detect the blank value. In order to determine the same 8 types of DNAts in 10 samples, the 10 DNAc-modified subarrays on the microarray are identical. Fluorescence single-molecule images of the QD-labeled DNAts on each spot of the subarray are acquired using a home-made single-molecule microarray reader. The amounts of the DNAts are quantified by counting the bright dots from the QDs. For a microarray, 8 types of DNAts in 10 samples can be quantified in parallel. The limit of detection of the SMA for DNA determination is as low as 1.3 × 10{sup −16} mol L{sup −1}. The SMA for multi-DNA determination can also be applied in single-cell multiple gene expression analysis through quantification of complementary DNAs (cDNAs) corresponding to multiple messenger RNAs (mRNAs) in single cells. To do so, total RNA in single cells is extracted and reversely transcribed into their cDNAs. Three

The tetracycline resistance determinant Tet 39 and the sulphonamide resistance gene sulII are common among resistant Acinetobacter spp. isolated from integrated fish farms in Thailand

DEFF Research Database (Denmark)

Agersø, Yvonne; Petersen, Andreas

2007-01-01

Objectives: To determine the genetic basis for tetracycline and sulphonamide resistance and the prevalence of class I and II integrons in oxytetracycline-resistant Acinetobacter spp. from integrated fish farms in Thailand. Methods: A total of 222 isolates were screened for tetracycline resistance...... and Southern blots with sulII and tet(39) probes were performed on selected isolates. Results: The recently identified tetracycline resistance gene tet(39) was demonstrated in 75% (166/222) of oxytetracycline-resistant Acinetobacter spp. from integrated fish farms in Thailand. Isolates that were also...

In vitro comparison of the cyclic fatigue resistance of HyFlex EDM, One G, and ProGlider nickel titanium glide path instruments in single and double curvature canals.

Science.gov (United States)

Yılmaz, Koray; Uslu, Gülşah; Özyürek, Taha

2017-11-01

It was aimed to compare the cyclic fatigue resistances of ProGlider (PG), One G (OG), and HyFlex EDM (HEDM) nickel titanium glide path files in single- and double-curved artificial canals. 40 PG (16/0.02), 40 OG (14/0.03), and 40 HEDM (10/0.05) single-file glide path files were used in the present study. Sixty files were subjected to cyclic fatigue test by using double-curved canals and 60 files by using single-curved canal ( n = 20). The number of cycles to fracture (NCF) was calculated and the length of the fractured fragment (FL) was determined by a digital micro-caliper. Twelve pieces of fractured files were examined with scanning electron microscope to determine fracture types of the files ( n = 2). The NCF and the FL data were analyzed using one-way analysis of variance and post hoc Tukey test using SPSS 21 software ( p < 0.05). In all of the groups, NCF values were significantly lower in double-curved canals when compared to single-curved canals ( p < 0.05). For both of single- and double-curved canals, NCF values of HEDM group in apical and coronal curvatures were found to be significantly higher than NCF values of PG and OG groups ( p < 0.05). In both of single- and double-curved canals, NCF value of PG group was found significantly higher than OG group ( p < 0.05). Within the limitations of this study, HEDM glide path files were found to have the highest cyclic fatigue resistance in both of single- and double-curved canals.

Determination and Application of Comprehensive Specific Frictional Resistance in Heating Engineering

Directory of Open Access Journals (Sweden)

Yanan Tian

2018-01-01

Full Text Available In this study, we analyze the deficiencies of specific frictional resistance in heating engineering. Based on economic specific frictional resistance, we put forward the concept of comprehensive specific frictional resistance, which considers the multiple factors of technology, economy, regulation modes, pipe segment differences, and medium pressure. Then, we establish a mathematical model of a heating network across its lifespan in order to develop a method for determining the comprehensive specific frictional resistance. Relevant conclusions can be drawn from the results. As an application, we have planned the heating engineering for Yangyuan County in China, which demonstrates the feasibility and superiority of the method.

Larva-mediated chalkbrood resistance-associated single nucleotide polymorphism markers in the honey bee Apis mellifera.

Science.gov (United States)

Liu, Y; Yan, L; Li, Z; Huang, W-F; Pokhrel, S; Liu, X; Su, S

2016-06-01

Chalkbrood is a disease affecting honey bees that seriously impairs brood growth and productivity of diseased colonies. Although honey bees can develop chalkbrood resistance naturally, the details underlying the mechanisms of resistance are not fully understood, and no easy method is currently available for selecting and breeding resistant bees. Finding the genes involved in the development of resistance and identifying single nucleotide polymorphisms (SNPs) that can be used as molecular markers of resistance is therefore a high priority. We conducted genome resequencing to compare resistant (Res) and susceptible (Sus) larvae that were selected following in vitro chalkbrood inoculation. Twelve genomic libraries, including 14.4 Gb of sequence data, were analysed using SNP-finding algorithms. Unique SNPs derived from chromosomes 2 and 11 were analysed in this study. SNPs from resistant individuals were confirmed by PCR and Sanger sequencing using in vitro reared larvae and resistant colonies. We found strong support for an association between the C allele at SNP C2587245T and chalkbrood resistance. SNP C2587245T may be useful as a genetic marker for the selection of chalkbrood resistance and high royal jelly production honey bee lines, thereby helping to minimize the negative effects of chalkbrood on managed honey bees. © 2016 The Royal Entomological Society.

A single alcohol drinking session is sufficient to enable subsequent aversion-resistant consumption in mice.

Science.gov (United States)

Lei, Kelly; Wegner, Scott A; Yu, Ji-Hwan; Simms, Jeffrey A; Hopf, F Woodward

2016-09-01

Addiction is mediated in large part by pathological motivation for rewarding, addictive substances, and alcohol-use disorders (AUDs) continue to extract a very high physical and economic toll on society. Compulsive alcohol drinking, where intake continues despite negative consequences, is considered a particular obstacle during treatment of AUDs. Aversion-resistant drives for alcohol have been modeled in rodents, where animals continue to consume even when alcohol is adulterated with the bitter tastant quinine, or is paired with another aversive consequence. Here, we describe a two-bottle choice paradigm where C57BL/6 mice first had 24-h access to 15% alcohol or water. Afterward, they drank quinine-free alcohol (alcohol-only) or alcohol with quinine (100 μM), in a limited daily access (LDA) two-bottle-choice paradigm (2 h/day, 5 days/week, starting 3 h into the dark cycle), and achieved nearly binge-level blood alcohol concentrations. Interestingly, a single, initial 24-h experience with alcohol-only enhanced subsequent quinine-resistant drinking. In contrast, mice that drank alcohol-quinine in the 24-h session showed significantly reduced alcohol-quinine intake and preference during the subsequent LDA sessions, relative to mice that drank alcohol-only in the initial 24-h session and alcohol-quinine in LDA sessions. Thus, mice could find the concentration of quinine we used aversive, but were able to disregard the quinine after a single alcohol-only drinking session. Finally, mice had low intake and preference for quinine in water, both before and after weeks of alcohol-drinking sessions, suggesting that quinine resistance was not a consequence of increased quinine preference after weeks of drinking of alcohol-quinine. Together, we demonstrate that a single alcohol-only session was sufficient to enable subsequent aversion-resistant consumption in C57BL/6 mice, which did not reflect changes in quinine taste palatability. Given the rapid development of quinine-resistant

Enhanced resistance to fluoroquinolones in laboratory-grown mutants & clinical isolates of Shigella due to synergism between efflux pump expression & mutations in quinolone resistance determining region

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Neelam Taneja

2015-01-01

Full Text Available Background & objectives: There is a worldwide emergence of fluoroquinolone resistance in Shigella species. To understand the molecular mechanisms associated with fluoroquinolone resistance, naturally occurring fluoroquinolone-resistant strains and laboratory-induced spontaneous mutants of Shigella spp. were used and the relative contributions of acrAB-tolC efflux pumps, gyrase and topoisomerase target gene mutations towards fluoroquinolone resistance were determined. Methods: Eight Shigella flexneri and six S. dysenteriae clinical isolates were studied. Three consecutive mutants resistant to ciprofloxacin for S. flexneri SFM1 (≥0.25 µg/ml, SFM2 (≥4 µg/ml and SFM3 (≥32 µg/ml were selected in 15 steps from susceptible isolates by serial exposure to increasing concentrations of nalidixic acid and ciprofloxacin. Similarly, two mutants for S. dysenteriae SDM1 (≥0.25 µg/ml and SDM2 (≥4 µg/ml were selected in eight steps. After PCR amplification sequence analyses of gyrase and topoisomerase target genes were performed. Expression of efflux genes acrA, acrB, acrR and tolC was measured using real-time PCR. Results: Mutations were observed in gyrA Ser [83]→Leu, Asp [87]→Asn/Gly, Val [196]→Ala and in parC Phe [93]→Val, Ser [80]→Ile, Asp [101]→Glu and Asp [110]→Glu. Overall, acrA and acrB overexpression was associated with fluoroquinolone resistance ( p0 <0.05; while tolC and acrR expression levels did not. Interpretation & conclusions: Fluoroquinolone resistance in Shigella spp. is the end product of either a single or a combination of mutations in QRDRs and/ or efflux activity. Novel polymorphisms were observed at Val [196]→Ala in gyrA in clinical isolates and Phe [93]→Val, Asp [101]→Glu, Asp [110]→Glu and in parC in majority of laboratory-grown mutants.

Determination of slope failure using 2-D resistivity method

Science.gov (United States)

Muztaza, Nordiana Mohd; Saad, Rosli; Ismail, Nur Azwin; Bery, Andy Anderson

2017-07-01

Landslides and slope failure may give negative economic effects including the cost to repair structures, loss of property value and medical costs in the event of injury. To avoid landslide, slope failure and disturbance of the ecosystem, good and detailed planning must be done when developing hilly area. Slope failure classification and various factors contributing to the instability using 2-D resistivity survey conducted in Selangor, Malaysia are described. The study on landslide and slope failure was conducted at Site A and Site B, Selangor using 2-D resistivity method. The implications of the anticipated ground conditions as well as the field observation of the actual conditions are discussed. Nine 2-D resistivity survey lines were conducted in Site A and six 2-D resistivity survey lines with 5 m minimum electrode spacing using Pole-dipole array were performed in Site B. The data were processed using Res2Dinv and Surfer10 software to evaluate the subsurface characteristics. 2-D resistivity results from both locations show that the study areas consist of two main zones. The first zone is alluvium or highly weathered with the resistivity of 100-1000 Ωm at 20-70 m depth. This zone consists of saturated area (1-100 Ωm) and boulders with resistivity value of 1200-3000 Ωm. The second zone with resistivity values of > 3000 Ωm was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. Based on the results obtained from the study findings, it can be concluded that 2-D resistivity method is useful method in determination of slope failure.

Study on Single-yarn Pullout Test of Ballistic Resistant Fabric under Different Preloads

Science.gov (United States)

Fang, Q. C.; Lei, Z. K.; Y Qin, F.; Li, W. K.; Bai, R. X.

2017-12-01

During bullet penetrating fabric, the pull-out force of yarn in fabric is related to the impact resistance of fabric when the yarn is pulled out from the fabric. The complex uncrimping and friction slip behavior occur during the yarn pullout process, which is critical to learn the impact resistance of fabric. Based on digital image correlation technique, the deformation behavior of Kevlar 49 fabric subjected to preload during the single-yarn pullout process was studied in this paper. The pullout force and displacement curve shows a straight rise and an oscillated decrease. In the linear rise stage, the yarn uncrimping causes a static friction effect. The maximum of the pullout force is not linearly increased with the preload. In the oscillating descending stage, the local descent of the pullout force indicates that the yarn end is gradually withdrawn from the fabric, and the local rise indicates that the yarn end moves to the next weft/warp interaction until the yarn is completely pulled out. The shear deformation of fabric corresponds to the single-yarn pullout process.

Determination of Screw and Nail Withdrawal Resistance of Some Important Wood Species

Directory of Open Access Journals (Sweden)

Alper Aytekin

2008-04-01

Full Text Available In this study, screw and nail withdrawal resistance of fir (Abies nordmanniana, oak (Quercus robur L. black pine (Pinus nigra Arnold and Stone pine (Pinus pinea L. wood were determined and compared. The data represent the testing of withdrawal resistance of three types of screws as smart, serrated and conventional and common nails. The specimens were prepared according to TS 6094 standards. The dimensions of the specimens were 5x5x15cm and for all of the directions. Moreover, the specimens were conditioned at ambient room temperature and 65±2% relative humidity. The screws and nails were installed according to ASTM-D 1761 standards. Nail dimensions were 2.5mm diameter and 50 mm length, conventional screws were 4x50mm, serrated screws were 4x45mm and smart screws were 4x50mm. Results show that the maximum screw withdrawal resistance value was found in Stone pine for the serrated screw. There were no significant differences between Stone pine and oak regarding screw withdrawal resistance values. Conventional screw yielded the maximum screw withdrawal resistance value in oak, followed by Stone pine, black pine and fir. Oak wood showed the maximum screw withdrawal resistance value for the smart screw, followed by Stone pine, black pine, and fir. Oak wood showed higher nail withdrawal resistances than softwood species. It was also determined that oak shows the maximum nail withdrawal resistance in all types. The nail withdrawal resistances at the longitudinal direction are lower with respect to radial and tangential directions.

Antibiotic resistance determinants in a Pseudomonas putida strain isolated from a hospital.

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Lázaro Molina

Full Text Available Environmental microbes harbor an enormous pool of antibiotic and biocide resistance genes that can impact the resistance profiles of animal and human pathogens via horizontal gene transfer. Pseudomonas putida strains are ubiquitous in soil and water but have been seldom isolated from humans. We have established a collection of P. putida strains isolated from in-patients in different hospitals in France. One of the isolated strains (HB3267 kills insects and is resistant to the majority of the antibiotics used in laboratories and hospitals, including aminoglycosides, ß-lactams, cationic peptides, chromoprotein enediyne antibiotics, dihydrofolate reductase inhibitors, fluoroquinolones and quinolones, glycopeptide antibiotics, macrolides, polyketides and sulfonamides. Similar to other P. putida clinical isolates the strain was sensitive to amikacin. To shed light on the broad pattern of antibiotic resistance, which is rarely found in clinical isolates of this species, the genome of this strain was sequenced and analysed. The study revealed that the determinants of multiple resistance are both chromosomally-borne as well as located on the pPC9 plasmid. Further analysis indicated that pPC9 has recruited antibiotic and biocide resistance genes from environmental microorganisms as well as from opportunistic and true human pathogens. The pPC9 plasmid is not self-transmissible, but can be mobilized by other bacterial plasmids making it capable of spreading antibiotic resistant determinants to new hosts.

Prevalence of genetic determinants and phenotypic resistance to ciprofloxacin in Campylobacter jejuni from lithuania

DEFF Research Database (Denmark)

Aksomaitiene, Jurgita; Ramonaite, Sigita; Olsen, John E.

2018-01-01

Recently, the number of reports on isolation of ciprofloxacin resistant Campylobacter jejuni has increased worldwide. The aim of this study was to determine the prevalence of resistance to ciprofloxacin and its genetic determinants among C. jejuni isolated from humans (n = 100), poultry products (n...... = 96) and wild birds (n = 96) in Lithuania. 91.4% of the C. jejuni isolates were phenotypically resistant to ciprofloxacin. DNA sequence analyses of the gyrA gene from 292 isolates revealed that a change in amino acid sequence, Thr86Ile, was the main substition conferring resistance to ciprofloxacin...... forty-five C. jejuni isolates showed one or more silent mutations, and 32.4% of examined isolates possessed six silent mutations. In addition to the ciprofloxacin resistant isolates harboring only Thr86Ile point mutation (110 isolates), the current study identified resistant isolates (n = 101) harboring...

Unique Determinants of Neuraminidase Inhibitor Resistance among N3, N7, and N9 Avian Influenza Viruses.

Science.gov (United States)

Song, Min-Suk; Marathe, Bindumadhav M; Kumar, Gyanendra; Wong, Sook-San; Rubrum, Adam; Zanin, Mark; Choi, Young-Ki; Webster, Robert G; Govorkova, Elena A; Webby, Richard J

2015-11-01

Human infections with avian influenza viruses are a serious public health concern. The neuraminidase (NA) inhibitors (NAIs) are the frontline anti-influenza drugs and are the major option for treatment of newly emerging influenza. Therefore, it is essential to identify the molecular markers of NAI resistance among specific NA subtypes of avian influenza viruses to help guide clinical management. NAI-resistant substitutions in NA subtypes other than N1 and N2 have been poorly studied. Here, we identified NA amino acid substitutions associated with NAI resistance among influenza viruses of N3, N7, and N9 subtypes which have been associated with zoonotic transmission. We applied random mutagenesis and generated recombinant influenza viruses carrying single or double NA substitution(s) with seven internal genes from A/Puerto Rico/8/1934 (H1N1) virus. In a fluorescence-based NA inhibition assay, we identified three categories of NA substitutions associated with reduced inhibition by NAIs (oseltamivir, zanamivir, and peramivir): (i) novel subtype-specific substitutions in or near the enzyme catalytic site (R152W, A246T, and D293N, N2 numbering), (ii) subtype-independent substitutions (E119G/V and/or D and R292K), and (iii) substitutions previously reported in other subtypes (Q136K, I222M, and E276D). Our data show that although some markers of resistance are present across NA subtypes, other subtype-specific markers can only be determined empirically. The number of humans infected with avian influenza viruses is increasing, raising concerns of the emergence of avian influenza viruses resistant to neuraminidase (NA) inhibitors (NAIs). Since most studies have focused on NAI-resistance in human influenza viruses, we investigated the molecular changes in NA that could confer NAI resistance in avian viruses grown in immortalized monolayer cells, especially those of the N3, N7, and N9 subtypes, which have caused human infections. We identified not only numerous NAI-resistant

Heat-transfer resistance at solid-liquid interfaces: a tool for the detection of single-nucleotide polymorphisms in DNA.

Science.gov (United States)

van Grinsven, Bart; Vanden Bon, Natalie; Strauven, Hannelore; Grieten, Lars; Murib, Mohammed; Monroy, Kathia L Jiménez; Janssens, Stoffel D; Haenen, Ken; Schöning, Michael J; Vermeeren, Veronique; Ameloot, Marcel; Michiels, Luc; Thoelen, Ronald; De Ceuninck, Ward; Wagner, Patrick

2012-03-27

In this article, we report on the heat-transfer resistance at interfaces as a novel, denaturation-based method to detect single-nucleotide polymorphisms in DNA. We observed that a molecular brush of double-stranded DNA grafted onto synthetic diamond surfaces does not notably affect the heat-transfer resistance at the solid-to-liquid interface. In contrast to this, molecular brushes of single-stranded DNA cause, surprisingly, a substantially higher heat-transfer resistance and behave like a thermally insulating layer. This effect can be utilized to identify ds-DNA melting temperatures via the switching from low- to high heat-transfer resistance. The melting temperatures identified with this method for different DNA duplexes (29 base pairs without and with built-in mutations) correlate nicely with data calculated by modeling. The method is fast, label-free (without the need for fluorescent or radioactive markers), allows for repetitive measurements, and can also be extended toward array formats. Reference measurements by confocal fluorescence microscopy and impedance spectroscopy confirm that the switching of heat-transfer resistance upon denaturation is indeed related to the thermal on-chip denaturation of DNA. © 2012 American Chemical Society

Non-invasive determination of absolute lung resistivity in adults using electrical impedance tomography

International Nuclear Information System (INIS)

Zhang, Jie; Patterson, Robert

2010-01-01

Lung resistivity is a physiological parameter that describes the electrical characteristics of the lungs. Lung composition changes due to changes in the lung tissues, fluid and air volume. Various diseases that can cause a change in lung composition may be monitored by measuring lung resistivity. Currently, there is no accepted non-invasive method to measure lung resistivity. In this study, we presented a method and framework to non-invasively determine lung resistivity using electrical impedance tomography (EIT). By comparing actual measurements from subjects with data from a 3D human thorax model, an EIT image can be reconstructed to show a resistivity difference between the model and the subject. By adjusting the lung resistivity in the model, the resistivity difference in the lung regions can be reduced to near zero. This resistivity value then is the estimation of the lung resistivity of the subject. Using the proposed method, the lung resistivities of four normal adult males (43 ± 13 years, 78 ± 10 kg) in the supine position at air volumes starting at functional residual capacity (FRC—end expiration) and increasing in 0.5 l steps to 1.5 l were studied. The averaged lung resistivity changes 12.59%, from 1406 Ω cm to 1583 Ω cm, following the inspiration of 1.5 l air from FRC. The coefficients of variation (CV) of precision for the four subjects are less than 10%. The experiment was repeated five times at each air volume on a subject to test the reproducibility. The CVs are less than 3%. The results show that it is feasible to determine absolute lung resistivity using an EIT-based method

Non-invasive determination of absolute lung resistivity in adults using electrical impedance tomography.

Science.gov (United States)

Zhang, Jie; Patterson, Robert

2010-08-01

Lung resistivity is a physiological parameter that describes the electrical characteristics of the lungs. Lung composition changes due to changes in the lung tissues, fluid and air volume. Various diseases that can cause a change in lung composition may be monitored by measuring lung resistivity. Currently, there is no accepted non-invasive method to measure lung resistivity. In this study, we presented a method and framework to non-invasively determine lung resistivity using electrical impedance tomography (EIT). By comparing actual measurements from subjects with data from a 3D human thorax model, an EIT image can be reconstructed to show a resistivity difference between the model and the subject. By adjusting the lung resistivity in the model, the resistivity difference in the lung regions can be reduced to near zero. This resistivity value then is the estimation of the lung resistivity of the subject. Using the proposed method, the lung resistivities of four normal adult males (43 +/- 13 years, 78 +/- 10 kg) in the supine position at air volumes starting at functional residual capacity (FRC--end expiration) and increasing in 0.5 l steps to 1.5 l were studied. The averaged lung resistivity changes 12.59%, from 1406 Omega cm to 1583 Omega cm, following the inspiration of 1.5 l air from FRC. The coefficients of variation (CV) of precision for the four subjects are less than 10%. The experiment was repeated five times at each air volume on a subject to test the reproducibility. The CVs are less than 3%. The results show that it is feasible to determine absolute lung resistivity using an EIT-based method.

A single hole tracer test to determine longitudinal dispersion

International Nuclear Information System (INIS)

Noy, D.J.; Holmes, D.C.

1986-03-01

The paper concerns a single hole tracer test to determine longitudinal dispersion, which is an important parameter in assessing the suitability of a site for radioactive waste disposal. The theory, equipment and procedure for measuring longitudinal dispersion in a single borehole is described. Results are presented for field trials conducted in an aquifer, where the technique produced good results. The measured value of longitudinal dispersion, from a single hole test, relates only to a limited volume of rock immediately adjacent to the borehole. (U.K.)

Translocation of integron-associated resistance in a natural system: Acquisition of resistance determinants by Inc P and Inc W Plasmids from Salmonella enterica Typhimurium DT104

DEFF Research Database (Denmark)

Sandvang, Dorthe; Diggle, M.; Platt, D.J.

2002-01-01

to determinate the genetic content. Translocation to R751 and R388 was associated with the loss of the indigenous trimethoprim cassette to both plasmids and also acquisition of sulfonamide resistance by R751 and RP4::Tn7, which indicated movement of the 3' terminus of one or both of the DT104 integrons......Salmonella enterica Typhimurium DT104, 961368, a veterinary field isolate that encodes a chromosomal cluster of resistance genes as well as two integrons, was used to study the mobility of resistance cassettes (aadA2 and pse-1) and nonintegron-associated resistance determinants (chloramphenicol...... and tetracycline). A range of natural plasmids was used as targets for the translocation of resistance. Plasmids that acquired resistance from the DT104 chromosome were segregated by conjugation into Escherichia coli K12. Plasmids R751, R388, and RP4::Tn7 acquired several combinations of resistance determinant...

Mutations inside rifampicin-resistance determining region of rpoB gene associated with rifampicin-resistance in Mycobacterium tuberculosis.

Science.gov (United States)

Zaw, Myo T; Emran, Nor A; Lin, Zaw

2018-04-26

Rifampicin (RIF) plays a pivotal role in the treatment of tuberculosis due to its bactericidal effects. Because the action of RIF is on rpoB gene encoding RNA polymerase β subunit, 95% of RIF resistant mutations are present in rpoB gene. The majority of the mutations in rpoB gene are found within an 81bp RIF-resistance determining region (RRDR). Literatures on RIF resistant mutations published between 2010 and 2016 were thoroughly reviewed. The most commonly mutated codons in RRDR of rpoB gene are 531, 526 and 516. The possibilities of absence of mutation in RRDR of rpoB gene in MDR-TB isolates in few studies was due to existence of other rare rpoB mutations outside RRDR or different mechanism of rifampicin resistance. Molecular methods which can identify extensive mutations associated with multiple anti-tuberculous drugs are in urgent need so that the research on drug resistant mutations should be extended. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Use of the azimuthal resistivity technique for determination of regional azimuth of transmissivity

Science.gov (United States)

Carlson, D.

2010-01-01

Many bedrock units contain joint sets that commonly act as preferred paths for the movement of water, electrical charge, and possible contaminants associated with production or transit of crude oil or refined products. To facilitate the development of remediation programs, a need exists to reliably determine regional-scale properties of these joint sets: azimuth of transmissivity ellipse, dominant set, and trend(s). The surface azimuthal electrical resistivity survey method used for local in situ studies can be a noninvasive, reliable, efficient, and relatively cost-effective method for regional studies. The azimuthal resistivity survey method combines the use of standard resistivity equipment with a Wenner array rotated about a fixed center point, at selected degree intervals, which yields an apparent resistivity ellipse from which joint-set orientation can be determined. Regional application of the azimuthal survey method was tested at 17 sites in an approximately 500 km2 (193 mi2) area around Milwaukee, Wisconsin, with less than 15m (50 ft) overburden above the dolomite. Results of 26 azimuthal surveys were compared and determined to be consistent with the results of two other methods: direct observation of joint-set orientation and transmissivity ellipses from multiple-well-aquifer tests. The average of joint-set trend determined by azimuthal surveys is within 2.5?? of the average of joint-set trend determined by direct observation of major joint sets at 24 sites. The average of maximum of transmissivity trend determined by azimuthal surveys is within 5.7?? of the average of maximum of transmissivity trend determined for 14 multiple-well-aquifer tests. Copyright ?? 2010 The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Analysis of hepatitis C NS5A resistance associated polymorphisms using ultra deep single molecule real time (SMRT) sequencing.

Science.gov (United States)

Bergfors, Assar; Leenheer, Daniël; Bergqvist, Anders; Ameur, Adam; Lennerstrand, Johan

2016-02-01

Development of Hepatitis C virus (HCV) resistance against direct-acting antivirals (DAAs), including NS5A inhibitors, is an obstacle to successful treatment of HCV when DAAs are used in sub-optimal combinations. Furthermore, it has been shown that baseline (pre-existing) resistance against DAAs is present in treatment naïve-patients and this will potentially complicate future treatment strategies in different HCV genotypes (GTs). Thus the aim was to detect low levels of NS5A resistant associated variants (RAVs) in a limited sample set of treatment-naïve patients of HCV GT1a and 3a, since such polymorphisms can display in vitro resistance as high as 60000 fold. Ultra-deep single molecule real time (SMRT) sequencing with the Pacific Biosciences (PacBio) RSII instrument was used to detect these RAVs. The SMRT sequencing was conducted on ten samples; three of them positive with Sanger sequencing (GT1a Q30H and Y93N, and GT3a Y93H), five GT1a samples, and two GT3a non-positive samples. The same methods were applied to the HCV GT1a H77-plasmid in a dilution series, in order to determine the error rates of replication, which in turn was used to determine the limit of detection (LOD), as defined by mean + 3SD, of minority variants down to 0.24%. We found important baseline NS5A RAVs at levels between 0.24 and 0.5%, which could potentially have clinical relevance. This new method with low level detection of baseline RAVs could be useful in predicting the most cost-efficient combination of DAA treatment, and reduce the treatment duration for an HCV infected individual. Copyright © 2015 Elsevier B.V. All rights reserved.

Widespread distribution of a tet W determinant among tetracycline-resistant isolates of the animal pathogen Arcanobacterium pyogenes.

Science.gov (United States)

Billington, Stephen J; Songer, J Glenn; Jost, B Helen

2002-05-01

Tetracycline resistance is common among isolates of the animal commensal and opportunistic pathogen Arcanobacterium pyogenes. The tetracycline resistance determinant cloned from two bovine isolates of A. pyogenes was highly similar at the DNA level (92% identity) to the tet(W) gene, encoding a ribosomal protection tetracycline resistance protein, from the rumen bacterium Butyrivibrio fibrisolvens. The tet(W) gene was found in all 20 tetracycline-resistant isolates tested, indicating that it is a widely distributed determinant of tetracycline resistance in this organism. In 25% of tetracycline-resistant isolates, the tet(W) gene was associated with a mob gene, encoding a functional mobilization protein, and an origin of transfer, suggesting that the determinant may be transferable to other bacteria. In fact, low-frequency transfer of tet(W) was detected from mob+ A. pyogenes isolates to a tetracycline-sensitive A. pyogenes recipient. The mobile nature of this determinant and the presence of A. pyogenes in the gastrointestinal tract of cattle and pigs suggest that A. pyogenes may have inherited this determinant within the gastrointestinal tracts of these animals.

Use of Single-Tow Ceramic Matrix Minicomposites to Determine Fundamental Room and Elevated Temperature Properties

Science.gov (United States)

Almansour, Amjad S.

The room and high temperature mechanical properties of continuous ceramic fiber reinforced matrix composites makes them attractive for implementation in aerospace and nuclear applications. However, the effect of fiber content has not been addressed in previous work. Therefore, single tow composites with fiber content ranging from 3 to 47 % was studied. Single fiber tow minicomposite is the basic architectural feature of woven and laminate ceramic matrix composites (CMCs). An in depth understanding of the initiation and evolution of damage in various ceramic fiber reinforced minicomposites with different fiber volume fractions and interphases was investigated employing several non-destructive evaluation techniques. A new technique is used to determine matrix crack content based on a damage parameter derived from speed of sound measurements which is compared with the established method using cumulative energy of Acoustic Emission (AE) events. Also, a modified theoretical model was implemented to obtain matrix stress at the onset of matrix cracking. Room temperature tensile, high temperature creep rupture and high temperature oxidation degradation loading conditions were all considered and composites' constituents were characterized. Moreover, fibers/matrix load sharing was modeled in creep and fiber volume fraction effect on load transfer was investigated using derived theoretical models. Fibers and matrix creep parameters, load transfer model results and numerical model methodology were used to construct minicomposites' creep strain model to predict creep damage of the different fiber type and content minicomposites. Furthermore, different fiber volume fractions ceramic matrix minicomposites' electrical resistivity temperature dependence isn't well understood. Therefore, the influence of fiber content, heat treatment cycles and creep on electrical resistivity measurements of SiC/SiC minicomposites were also studied here. Next, minicomposites' testing and

Determining resistance to mastitis in a bovine subject comprises detecting the presence or absence of a genetic marker that is linked to a trait indicative of mastitis resistance

DEFF Research Database (Denmark)

2007-01-01

The invention relates to a method for determining mastitis resistance in bovine subjects, wherein mastitis resistance comprise resistance to both sub-clinical and clinical mastitis. In particular, the method of the invention involves identification of genetic markers and/or Quantitative Trait Locus...... (QTL) for the determination of mastitis resistance in a bovine subject. The determination of mastitis resistance involves resolution of the specific microsatellite status. Furthermore, the invention relates to a diagnostic kit for detection of genetic marker(s) associated with mastitis resistance....... The method and kit of the present invention can be applied for selection of bovine subjects for breeding purposes. Thus, the invention provides a method of genetically selecting bovine subjects with mastitis resistance, thereby yielding cows less prone to mastitis...

Cloning and DNA sequence of the mercuric- and organomercurial-resistance determinants of plasmid pDU1358

International Nuclear Information System (INIS)

Griffin, H.G.; Foster, T.J.; Silver, S.; Misra, T.K.

1987-01-01

The broad-spectrum mercurial-resistance plasmid pDU1358 was analyzed by cloning the resistance determinants and preparing a physical and genetic map of a 45-kilobase (kb) region of the plasmid that contains two separate mercurial-resistance operons that mapped about 20 kb apart. One encoded narrow-spectrum mercurial resistance to Hg 2+ and a few organomercurials; the other specified broad-spectrum resistance to phenylmercury and additional organomercurials. Each determinant governed mercurial transport functions. Southern DNA x DNA hybridization experiments using gene-specific probes from the plasmid R100 mer operon indicated close homology with the R100 deteminant. The 2153 base pairs of the promoter-distal part of the broad-spectrum Hg 2+ -resistance operon of pDU1358 were sequenced. This region included the 3'-terminal part of the merA gene, merD, unidentified reading frame URF1, and a part of URF2 homologous to previously sequenced determinants of plasmid R100. Between the merA and merD genes, an open reading frame encoding a 212 amino acid polypeptide was identified as the merB gene that determines the enzyme organomercurial lyase that cleaves the C-Hg bond of phenylmercury

Socioeconomic Determinants of Ciprofloxacin-Resistant Shigella Infections in Bangladeshi Children

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Randon J. Gruninger

2017-03-01

Full Text Available Background: Shigella species (spp. are a leading cause of moderate to severe diarrhea in children worldwide. The recent emergence of quinolone-resistant Shigella spp. gives cause for concern, and South Asia has been identified as a reservoir for global spread. The influence of socioeconomic status on antimicrobial resistance in developing countries, such as those in South Asia, remains unknown. Methods: We used data collected from 2009 to 2014 from a hospital specializing in the treatment of diarrhea in Dhaka, Bangladesh, to determine the relationship between ciprofloxacin-resistant Shigella spp. isolates and measures of socioeconomic status in Bangladeshi children less than 5 years of age. Results: We found 2.7% (230/8, 672 of children who presented with diarrhea had Shigella spp. isolated from their stool, and 50% (115/230 had resistance to ciprofloxacin. Using multivariable logistic regression analysis, we found that children from families where the father’s income was in the highest quintile had significantly higher odds of having ciprofloxacin-resistant Shigella spp. compared to children in the lowest quintile (OR = 6.1, CI 1.9-19. Factors protective against the development of resistance included access to improved sanitation (OR = 0.27, CI 0.11-0.7, and improved water sources (OR = 0.48, CI 0.25-0.92. We did not find a relationship between ciprofloxacin resistance and other proxies for socioeconomic status, including the presence of animals in the home, nutritional status, paternal education level, and the number of family members in the home. Conclusions: Although the associations between wealth and antimicrobial resistance are not fully understood, possible explanations include increased access and use of antibiotics, greater access to healthcare facilities and thus resistant pathogens, or greater consumption of commercially produced foods prepared with antibiotics.

Determination of Serotypes and Antibiotic Resistance in Streptococcus Pneumoniae

Directory of Open Access Journals (Sweden)

Deniz Akgun Karapinar

2016-01-01

Full Text Available Aim: In this study, the distribution of serogroup/serotype and antibiotic susceptibility testing of Streptococcus pneumoniae strains, recovered from pediatric and adult patients were evaluated. Material and Method: A total of 80 clinical isolates recovered from 19 pediatric and 61 adult patients were performed by latex aglutination method and antibiotic susceptibility tests in Istanbul University, Istanbul Faculty of Medicine, Medical Microbiology Laboratories. Results: Sixty-two strains (76 %, were serogroup/serotyped and 18 (23 % strains couldn%u2019t serogroup/serotyped. The most frequent identified serogroups were 19, 14, 23, 6, 4 in pediatrics, and 3, 19, 23 and 9 in adults. In adults, serogroups 3, 9, 5, 8, 18, 1, 15 were determined, but these serogroups weren%u2019t found in pediatrics. Vaccine serotypes rates were found as 53 % in pediatric and as 85 % in adults. The serogroups 2, 7, 10, 11, 12, 17, 20, 22, 33 were not detected, which are available in vaccine serotypes. Only 1 (1 % strain was found to exhibit low level resistance to penicillin and high level resistance wasn%u2019t found in any strain. Resistant results for trimethoprim-sulfamethoxazole, erythromycin, chloramphenicol and ofloxacin were found as 45 (56 %, 22 (27.5 %, 7 (9 %, 2 (2.5 %, respectively. All strains were found susceptible to vancomycin, linezolid and levofloxacin. The most resistant serogroups were 19, 23, 9 and 14 in the tested antibiotics. Multidrug resistance was found in 9 (11 % strains and these strains were found as serogroups 19, 23, 9, 6 and 14. Discussion: The epidemiological studies are important that the distribution of serotype and antibiotic resistance vary depending on many factors like age, and geographic region.

Fatigue resistance of 2 different CAD/CAM glass-ceramic materials used for single-tooth implant crowns.

Science.gov (United States)

Çavuşoğlu, Yeliz; Sahin, Erdal; Gürbüz, Riza; Akça, Kivanç

2011-10-01

To evaluate the fatigue resistance of 2 different CAD/CAM in-office monoceramic materials with single-tooth implant-supported crowns in functional area. A metal experimental model with a dental implant was designed to receive in-office CAD/CAM-generated monoceramic crowns. Laterally positioned axial dynamic loading of 300 N at 2 Hz was applied to implant-supported crowns machined from 2 different glass materials for 100,000 cycle. Failures in terms of fracture, crack formation, and chipping were macroscopically recorded and microscopically evaluated. Four of 10 aluminasilicate glass-ceramic crowns fractured at early loading cycles, the rest completed loading with a visible crack formation. Crack formation was recorded for 2 of 10 leucite glass-ceramic crowns. Others completed test without visible damage but fractured upon removal. Lack in chemical adhesion between titanium abutment and dental cement likely reduces the fatigue resistance of machinable glass-ceramic materials. However, relatively better fractural strength of leucite glass-ceramics could be taken into consideration. Accordingly, progress on developmental changes in filler composition of glass-ceramics may be promising. Machinable glass-ceramics do not possess sufficient fatigue resistance for single-tooth implant crowns in functional area.

Normal state resistivity of single crystalline V3Si as a function of neutron irradiation

International Nuclear Information System (INIS)

Caton, R.; Viswanathan, R.

1978-01-01

Analysis of the normal state resistivity of a neutron damaged single crystal of V 3 Si shows two different regions of behavior: one for T/sub c/ equal to or greater than 10 0 K and another for T/sub c/ equal to or less than 10 0 K

The coherent interlayer resistance of a single, rotated interface between two stacks of AB graphite

Energy Technology Data Exchange (ETDEWEB)

Habib, K. M. Masum, E-mail: khabib@ee.ucr.edu; Sylvia, Somaia S.; Neupane, Mahesh; Lake, Roger K., E-mail: rlake@ee.ucr.edu [Department of Electrical Engineering, University of California, Riverside, California 92521-0204 (United States); Ge, Supeng [Department of Physics and Astronomy, University of California, Riverside, California 92521-0204 (United States)

2013-12-09

The coherent, interlayer resistance of a misoriented, rotated interface between two stacks of AB graphite is determined for a variety of misorientation angles. The quantum-resistance of the ideal AB stack is on the order of 1 to 10 mΩ μm{sup 2}. For small rotation angles, the coherent interlayer resistance exponentially approaches the ideal quantum resistance at energies away from the charge neutrality point. Over a range of intermediate angles, the resistance increases exponentially with cell size for minimum size unit cells. Larger cell sizes, of similar angles, may not follow this trend. The energy dependence of the interlayer transmission is described.

The coherent interlayer resistance of a single, rotated interface between two stacks of AB graphite

International Nuclear Information System (INIS)

Habib, K. M. Masum; Sylvia, Somaia S.; Neupane, Mahesh; Lake, Roger K.; Ge, Supeng

2013-01-01

The coherent, interlayer resistance of a misoriented, rotated interface between two stacks of AB graphite is determined for a variety of misorientation angles. The quantum-resistance of the ideal AB stack is on the order of 1 to 10 mΩ μm 2 . For small rotation angles, the coherent interlayer resistance exponentially approaches the ideal quantum resistance at energies away from the charge neutrality point. Over a range of intermediate angles, the resistance increases exponentially with cell size for minimum size unit cells. Larger cell sizes, of similar angles, may not follow this trend. The energy dependence of the interlayer transmission is described

Monitoring of drug resistance amplification and attenuation with the use of tetracycline-resistant bacteria during wastewater treatment

Science.gov (United States)

Harnisz, Monika; Korzeniewska, Ewa; Niestępski, Sebastian; Osińska, Adriana; Nalepa, Beata

2017-11-01

The objective of this study was to monitor changes (amplification or attenuation) in antibiotic resistance during wastewater treatment based on the ecology of tetracycline-resistant bacteria. The untreated and treated wastewater were collected in four seasons. Number of tetracycline-(TETR) and oxytetracycline-resistant (OTCR) bacteria, their qualitative composition, minimum inhibitory concentrations (MICs), sensitivity to other antibiotics, and the presence of tet (A, B, C, D, E) resistance genes were determined. TETR and OTCR counts in untreated wastewater were 100 to 1000 higher than in treated effluent. OTCR bacterial counts were higher than TETR populations in both untreated and treated wastewater. TETR isolates were not dominated by a single bacterial genus or species, whereas Aeromonas hydrophila and Aeromonas sobria were the most common in OTCR isolates. The treatment process attenuated the drug resistance of TETR bacteria and amplified the resistance of OTCR bacteria. In both microbial groups, the frequency of tet(A) gene increased in effluent in comparison with untreated wastewater. Our results also indicate that treated wastewater is a reservoir of multiple drug-resistant bacteria as well as resistance determinants which may pose a health hazard for humans and animals when released to the natural environment.

Kapitza thermal resistance studied by high-frequency photothermal radiometry

International Nuclear Information System (INIS)

Horny, Nicolas; Chirtoc, Mihai; Hamaoui, Georges; Fleming, Austin; Ban, Heng

2016-01-01

Kapitza thermal resistance is determined using high-frequency photothermal radiometry (PTR) extended for modulation up to 10 MHz. Interfaces between 50 nm thick titanium coatings and silicon or stainless steel substrates are studied. In the used configuration, the PTR signal is not sensitive to the thermal conductivity of the film nor to its optical absorption coefficient, thus the Kapitza resistance is directly determined from single thermal parameter fits. Results of thermal resistances show the significant influence of the nature of the substrate, as well as of the presence of free electrons at the interface.

The Effect of Single Portion Glutamine Supplement Consumption on Injury Indices of Muscle After Eccentric Resistance Exercise

OpenAIRE

Azadeh Najarzadeh; Hadi Atarod; Hasan Mozaffari-Khosravi; Ali Dehghani; Foad Asjodi

2015-01-01

Abstract Background: Delayed muscular soreness after resistance exercises or eccentric trainings is probably because of muscle damage and injury. Nutrition by playing a crucial role in both protein synthesize and catabolism can influence the extent of muscle injury. The objective of this study was to assess the effect of single portion of Glutamine supplement consumption on injury indices of muscle after a session eccentric resistance exercise. Materials and Methods: this study used a ...

Combinations of macrolide resistance determinants in field isolates of Mannheimia haemolytica and Pasteurella multocida

DEFF Research Database (Denmark)

Desmolaize, Benoit; Rose, Simon; Wilhelm, Cornelia

2011-01-01

of these species exhibit resistance to veterinary macrolides with phenotypes that fall into three distinct classes. The first class has type I macrolide, lincosamide, and streptogramin B antibiotic resistance and, consistent with this, the 23S rRNA nucleotide A2058 is monomethylated by the enzyme product......(E) genes within an isogenic Escherichia coli background to assess their individually contributions to resistance. Our findings indicate what types of compounds might have driven the selection for these resistance determinants....

Using data on resistance prevalence per sample in the surveillance of antimicrobial resistance

DEFF Research Database (Denmark)

Vieira, Antonio; Shuyu, Wu; Jensen, Lars Bogø

2008-01-01

Objectives: In most existing antimicrobial resistance monitoring programmes, one single bacterial colony from each collected sample is susceptibility tested against a panel of antimicrobials. Detecting the proportion of colonies resistant to different antimicrobials in each sample can provide...... quantitative data on antimicrobial resistance (resistance prevalence per sample). Methods: In this study, a total of 98 faecal samples from slaughter pigs were tested for tetracycline and sulphonamide resistance in Escherichia coli using the single colony method, and these results were compared...... with the results obtained using the resistance prevalence per sample method. Results: The results obtained by the resistance prevalence per sample method showed a lower occurrence of resistance. Tetracycline resistance in E. coli was found in 36.7% of the samples using the single colony method, while the mean...

Determination of Soil Moisture Content using Laboratory Experimental and Field Electrical Resistivity Values

Science.gov (United States)

Hazreek, Z. A. M.; Rosli, S.; Fauziah, A.; Wijeyesekera, D. C.; Ashraf, M. I. M.; Faizal, T. B. M.; Kamarudin, A. F.; Rais, Y.; Dan, M. F. Md; Azhar, A. T. S.; Hafiz, Z. M.

2018-04-01

The efficiency of civil engineering structure require comprehensive geotechnical data obtained from site investigation. In the past, conventional site investigation was heavily related to drilling techniques thus suffer from several limitations such as time consuming, expensive and limited data collection. Consequently, this study presents determination of soil moisture content using laboratory experimental and field electrical resistivity values (ERV). Field and laboratory electrical resistivity (ER) test were performed using ABEM SAS4000 and Nilsson400 soil resistance meter. Soil sample used for resistivity test was tested for characterization test specifically on particle size distribution and moisture content test according to BS1377 (1990). Field ER data was processed using RES2DINV software while laboratory ER data was analyzed using SPSS and Excel software. Correlation of ERV and moisture content shows some medium relationship due to its r = 0.506. Moreover, coefficient of determination, R2 analyzed has demonstrate that the statistical correlation obtain was very good due to its R2 value of 0.9382. In order to determine soil moisture content based on statistical correlation (w = 110.68ρ-0.347), correction factor, C was established through laboratory and field ERV given as 19.27. Finally, this study has shown that soil basic geotechnical properties with particular reference to water content was applicably determined using integration of laboratory and field ERV data analysis thus able to compliment conventional approach due to its economic, fast and wider data coverage.

"Tissue oxygen tension, a determinant of resistance to infection and ...

African Journals Online (AJOL)

"Tissue oxygen tension, a determinant of resistance to infection and healing" - An Inaugural Lecture. K Jönsson. Abstract. An Inaugural Lecture Given in the University of Zimbabwe on 21 June 2001. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT.

Quantifying the Determinants of Evolutionary Dynamics Leading to Drug Resistance.

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Guillaume Chevereau

Full Text Available The emergence of drug resistant pathogens is a serious public health problem. It is a long-standing goal to predict rates of resistance evolution and design optimal treatment strategies accordingly. To this end, it is crucial to reveal the underlying causes of drug-specific differences in the evolutionary dynamics leading to resistance. However, it remains largely unknown why the rates of resistance evolution via spontaneous mutations and the diversity of mutational paths vary substantially between drugs. Here we comprehensively quantify the distribution of fitness effects (DFE of mutations, a key determinant of evolutionary dynamics, in the presence of eight antibiotics representing the main modes of action. Using precise high-throughput fitness measurements for genome-wide Escherichia coli gene deletion strains, we find that the width of the DFE varies dramatically between antibiotics and, contrary to conventional wisdom, for some drugs the DFE width is lower than in the absence of stress. We show that this previously underappreciated divergence in DFE width among antibiotics is largely caused by their distinct drug-specific dose-response characteristics. Unlike the DFE, the magnitude of the changes in tolerated drug concentration resulting from genome-wide mutations is similar for most drugs but exceptionally small for the antibiotic nitrofurantoin, i.e., mutations generally have considerably smaller resistance effects for nitrofurantoin than for other drugs. A population genetics model predicts that resistance evolution for drugs with this property is severely limited and confined to reproducible mutational paths. We tested this prediction in laboratory evolution experiments using the "morbidostat", a device for evolving bacteria in well-controlled drug environments. Nitrofurantoin resistance indeed evolved extremely slowly via reproducible mutations-an almost paradoxical behavior since this drug causes DNA damage and increases the mutation

Tutorial: Determination of thermal boundary resistance by molecular dynamics simulations

Science.gov (United States)

Liang, Zhi; Hu, Ming

2018-05-01

Due to the high surface-to-volume ratio of nanostructured components in microelectronics and other advanced devices, the thermal resistance at material interfaces can strongly affect the overall thermal behavior in these devices. Therefore, the thermal boundary resistance, R, must be taken into account in the thermal analysis of nanoscale structures and devices. This article is a tutorial on the determination of R and the analysis of interfacial thermal transport via molecular dynamics (MD) simulations. In addition to reviewing the commonly used equilibrium and non-equilibrium MD models for the determination of R, we also discuss several MD simulation methods which can be used to understand interfacial thermal transport behavior. To illustrate how these MD models work for various interfaces, we will show several examples of MD simulation results on thermal transport across solid-solid, solid-liquid, and solid-gas interfaces. The advantages and drawbacks of a few other MD models such as approach-to-equilibrium MD and first-principles MD are also discussed.

Label-free screening of single biomolecules through resistive pulse sensing technology for precision medicine applications

Science.gov (United States)

Harrer, S.; Kim, S. C.; Schieber, C.; Kannam, S.; Gunn, N.; Moore, S.; Scott, D.; Bathgate, R.; Skafidas, S.; Wagner, J. M.

2015-05-01

Employing integrated nano- and microfluidic circuits for detecting and characterizing biological compounds through resistive pulse sensing technology is a vibrant area of research at the interface of biotechnology and nanotechnology. Resistive pulse sensing platforms can be customized to study virtually any particle of choice which can be threaded through a fluidic channel and enable label-free single-particle interrogation with the primary read-out signal being an electric current fingerprint. The ability to perform label-free molecular screening with single-molecule and even single binding site resolution makes resistive pulse sensing technology a powerful tool for analyzing the smallest units of biological systems and how they interact with each other on a molecular level. This task is at the core of experimental systems biology and in particular ‘omics research which in combination with next-generation DNA-sequencing and next-generation drug discovery and design forms the foundation of a novel disruptive medical paradigm commonly referred to as personalized medicine or precision medicine. DNA-sequencing has approached the 1000-Dollar-Genome milestone allowing for decoding a complete human genome with unmatched speed and at low cost. Increased sequencing efficiency yields massive amounts of genomic data. Analyzing this data in combination with medical and biometric health data eventually enables understanding the pathways from individual genes to physiological functions. Access to this information triggers fundamental questions for doctors and patients alike: what are the chances of an outbreak for a specific disease? Can individual risks be managed and if so how? Which drugs are available and how should they be applied? Could a new drug be tailored to an individual’s genetic predisposition fast and in an affordable way? In order to provide answers and real-life value to patients, the rapid evolvement of novel computing approaches for analyzing big data in

Label-free screening of single biomolecules through resistive pulse sensing technology for precision medicine applications.

Science.gov (United States)

Harrer, S; Kim, S C; Schieber, C; Kannam, S; Gunn, N; Moore, S; Scott, D; Bathgate, R; Skafidas, S; Wagner, J M

2015-05-08

Employing integrated nano- and microfluidic circuits for detecting and characterizing biological compounds through resistive pulse sensing technology is a vibrant area of research at the interface of biotechnology and nanotechnology. Resistive pulse sensing platforms can be customized to study virtually any particle of choice which can be threaded through a fluidic channel and enable label-free single-particle interrogation with the primary read-out signal being an electric current fingerprint. The ability to perform label-free molecular screening with single-molecule and even single binding site resolution makes resistive pulse sensing technology a powerful tool for analyzing the smallest units of biological systems and how they interact with each other on a molecular level. This task is at the core of experimental systems biology and in particular 'omics research which in combination with next-generation DNA-sequencing and next-generation drug discovery and design forms the foundation of a novel disruptive medical paradigm commonly referred to as personalized medicine or precision medicine. DNA-sequencing has approached the 1000-Dollar-Genome milestone allowing for decoding a complete human genome with unmatched speed and at low cost. Increased sequencing efficiency yields massive amounts of genomic data. Analyzing this data in combination with medical and biometric health data eventually enables understanding the pathways from individual genes to physiological functions. Access to this information triggers fundamental questions for doctors and patients alike: what are the chances of an outbreak for a specific disease? Can individual risks be managed and if so how? Which drugs are available and how should they be applied? Could a new drug be tailored to an individual's genetic predisposition fast and in an affordable way? In order to provide answers and real-life value to patients, the rapid evolvement of novel computing approaches for analyzing big data in

Comparison of Several Methods for Determining the Internal Resistance of Lithium Ion Cells

Directory of Open Access Journals (Sweden)

Hans-Georg Schweiger

2010-06-01

Full Text Available The internal resistance is the key parameter for determining power, energy efficiency and lost heat of a lithium ion cell. Precise knowledge of this value is vital for designing battery systems for automotive applications. Internal resistance of a cell was determined by current step methods, AC (alternating current methods, electrochemical impedance spectroscopy and thermal loss methods. The outcomes of these measurements have been compared with each other. If charge or discharge of the cell is limited, current step methods provide the same results as energy loss methods.

DETERMINING THE THERMAL RESISTANCE OF A VENTILATED HINGED FACADE SYSTEM LAYER

Directory of Open Access Journals (Sweden)

Gagarin Vladimir Gennad'evich

2015-03-01

Full Text Available Enveloping structures with hinged façade systems are nowadays widely used for moisture control of enveloping structures, prevention of overheating of the structures by insolation, saving the constructions from atmospheric moisture and also for correspondence with the raised requirements to thermal protection of the enveloping structures, aimed also at reducing energy consumption. In the winter conditions the influence of air layer on the thermal insulation parameters is usually neglected. In the article the thermal resistance of an air gap and is considered and its effect in the calculation of the heat resistance of a building envelope with hinged facade system is analyzed in the conditions of cold weather. The thermal resistance of the air layer determines how the heat losses decrease.

Distribution of resistance genetic determinants among Vibrio cholerae isolates of 2012 and 2013 outbreaks in IR Iran.

Science.gov (United States)

Rezaie, Niloofar; Bakhshi, Bita; Najar-Peerayeh, Shahin

2017-03-01

The objective of this study was to characterize antimicrobial resistance determinants in relation to antimicrobial susceptibility and genotyping profile in 20 clinical isolates of Vibrio cholerae. All of the isolates were resistant to streptomycin. The second most prevalent resistance was observed to trimethoprim (75%), co-trimoxazole (60%), tetracycline (50%), and minocycline (45%). About 50% of the isolates fulfilled the criteria of Multi Drug Resistance (MDR) phenotype. None of the isolates carried tet A, B, C, and, D determinants. This finding shows that tetracycline resistance determinants recognized so far, does not satisfactorily describe the 50% tetracycline resistance phenotype in this study, suggesting the possible contribution of other not yet characterized resistance mechanisms involved. Class 1 integron, widely distributed among enteric bacteria, was not detected among V. cholerae strains under study. Conversely, 100% of the isolates harbored SXT constin (int) , among which 70% were positive for dfrA1, strA, and strB genes. The sul1gene was present in 60% of the isolates while none of them contained floR gene. All the isolates uniformly appeared to be identical in fingerprinting profiles expected from outbreak strains. In conclusion, SXT element with its mosaic structure was the exclusive antimicrobial resistance determinant of clonal V. cholerae isolates taken from outbreaks of 2012 and 2013 in Iran. Copyright © 2017 Elsevier Ltd. All rights reserved.

Single locus complementary sex determination in Hymenoptera : an "unintelligent" design?

NARCIS (Netherlands)

Wilgenburg, Ellen van; Driessen, Gerard; Beukeboom, Leo W.

2006-01-01

The haplodiploid sex determining mechanism in Hymenoptera (males are haploid, females are diploid) has played an important role in the evolution of this insect order. In Hymenoptera sex is usually determined by a single locus, heterozygotes are female and hemizygotes are male. Under inbreeding,

Single locus complementary sex determination in Hymenoptera: an "unintelligent" design?

NARCIS (Netherlands)

van Wilgenburg, E.; Driessen, G.J.J.; Beukeboom, L.W.

2006-01-01

The haplodiploid sex determining mechanism in Hymenoptera (males are haploid, females are diploid) has played an important role in the evolution of this insect order. In Hymenoptera sex is usually determined by a single locus, heterozygotes are female and hemizygotes are male. Under inbreeding,

Identification of Nevirapine-Resistant HIV-1 in the Latent Reservoir after Single-Dose Nevirapine to Prevent Mother-to-Child Transmission of HIV-1

Science.gov (United States)

Wind-Rotolo, Megan; Durand, Christine; Cranmer, Lisa; Reid, Alison; Martinson, Neil; Doherty, Meg; Jilek, Benjamin L.; Kagaayi, Joseph; Kizza, Allan; Pillay, Visva; Laeyendecker, Oliver; Reynolds, Steven J.; Eshleman, Susan H.; Lau, Bryan; Ray, Stuart C.; Siliciano, Janet D.; Quinn, Thomas C.; Siliciano, Robert F.

2009-01-01

Background Intrapartum single-dose nevirapine decreases mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1) but promotes nevirapine resistance. Although resistant viruses fade to undetectable levels in plasma, they may persist as stably integrated proviruses within the latent reservoir in resting CD4+ T cells, potentially complicating future treatment. Methods Blood samples were collected from 60 women from South Africa and Uganda >6 months after they had received single-dose nevirapine. To selectively analyze the stable latent form of HIV-1, resting CD4+ T cells were isolated and activated in the presence of reverse-transcriptase inhibitors and integrase inhibitors, which allows for the specific isolation of viruses produced by cells with stably integrated proviral DNA. These viruses were then analyzed for nevirapine resistance. Results Although only a small number of latently infected cells were present in each blood sample (mean, 162 cells), nevirapine resistance mutations (K103N and G190A) were detected in the latent reservoir of 4 (8%) of 50 evaluable women. Conclusions A single dose of nevirapine can establish antiretroviral resistance within the latent reservoir. This results in a potentially lifelong risk of reemergence of nevirapine-resistant virus and highlights the need for strategies to prevent transmission that do not compromise successful future treatment. PMID:19338474

Precise mass determination of single cell with cantilever-based microbiosensor system.

Directory of Open Access Journals (Sweden)

Bogdan Łabędź

Full Text Available Having determined the mass of a single cell of brewer yeast Saccharomyces cerevisiae by means of a microcantilever-based biosensor Cantisens CSR-801 (Concentris, Basel, Switzerland, it was found that its dry mass is 47,65 ± 1,05 pg. Found to be crucial in this mass determination was the cell position along the length of the cantilever. Moreover, calculations including cells positions on the cantilever provide a threefold better degree of accuracy than those which assume uniform mass distribution. We have also examined the influence of storage time on the single cell mass. Our results show that after 6 months there is an increase in the average mass of a single yeast cell.

Precise mass determination of single cell with cantilever-based microbiosensor system.

Science.gov (United States)

Łabędź, Bogdan; Wańczyk, Aleksandra; Rajfur, Zenon

2017-01-01

Having determined the mass of a single cell of brewer yeast Saccharomyces cerevisiae by means of a microcantilever-based biosensor Cantisens CSR-801 (Concentris, Basel, Switzerland), it was found that its dry mass is 47,65 ± 1,05 pg. Found to be crucial in this mass determination was the cell position along the length of the cantilever. Moreover, calculations including cells positions on the cantilever provide a threefold better degree of accuracy than those which assume uniform mass distribution. We have also examined the influence of storage time on the single cell mass. Our results show that after 6 months there is an increase in the average mass of a single yeast cell.

Development of transgenic watermelon resistant to Cucumber mosaic virus and Watermelon mosaic virus by using a single chimeric transgene construct.

Science.gov (United States)

Lin, Ching-Yi; Ku, Hsin-Mei; Chiang, Yi-Hua; Ho, Hsiu-Yin; Yu, Tsong-Ann; Jan, Fuh-Jyh

2012-10-01

Watermelon, an important fruit crop worldwide, is prone to attack by several viruses that often results in destructive yield loss. To develop a transgenic watermelon resistant to multiple virus infection, a single chimeric transgene comprising a silencer DNA from the partial N gene of Watermelon silver mottle virus (WSMoV) fused to the partial coat protein (CP) gene sequences of Cucumber mosaic virus (CMV), Cucumber green mottle mosaic virus (CGMMV) and Watermelon mosaic virus (WMV) was constructed and transformed into watermelon (cv. Feeling) via Agrobacterium-mediated transformation. Single or multiple transgene copies randomly inserted into various locations in the genome were confirmed by Southern blot analysis. Transgenic watermelon R(0) plants were individually challenged with CMV, CGMMV or WMV, or with a mixture of these three viruses for resistance evaluation. Two lines were identified to exhibit resistance to CMV, CGMMV, WMV individually, and a mixed inoculation of the three viruses. The R(1) progeny of the two resistant R(0) lines showed resistance to CMV and WMV, but not to CGMMV. Low level accumulation of transgene transcripts in resistant plants and small interfering (si) RNAs specific to CMV and WMV were readily detected in the resistant R(1) plants by northern blot analysis, indicating that the resistance was established via RNA-mediated post-transcriptional gene silencing (PTGS). Loss of the CGMMV CP-transgene fragment in R1 progeny might be the reason for the failure to resistant CGMMV infection, as shown by the absence of a hybridization signal and no detectable siRNA specific to CGMMV in Southern and northern blot analyses. In summary, this study demonstrated that fusion of different viral CP gene fragments in transgenic watermelon contributed to multiple virus resistance via PTGS. The construct and resistant watermelon lines developed in this study could be used in a watermelon breeding program for resistance to multiple viruses.

Origins of low resistivity in Al ion-implanted ZnO bulk single crystals

Science.gov (United States)

Oga, T.; Izawa, Y.; Kuriyama, K.; Kushida, K.; Kinomura, A.

2011-06-01

The origins of low resistivity in Al ion-implanted ZnO bulk single crystals are studied by combining Rutherford backscattering spectroscopy (RBS), nuclear reaction analysis (NRA), photoluminescence (PL), and Van der Pauw methods. The Al-ion implantation (peak concentration: 2.6 × 1020cm-3) into ZnO is performed using a multiple-step energy. The resistivity decreases from ˜104 Ω cm for un-implanted ZnO to 1.4 × 10-1 Ω cm for as-implanted, and reaches 6.0 × 10-4 Ω cm for samples annealed at 1000 °C. RBS and NRA measurements for as-implanted ZnO suggest the existence of the lattice displacement of Zn (Zni) and O (Oi), respectively. After annealing at 1000 °C, the Zni related defects remain and the Oi related defects disappear. The origin of the low resistivity in the as-implanted sample is attributed to the Zni (˜30 meV [Look et al., Phys. Rev. Lett. 82, 2552 (1999)]). In contrast, the origin of the low resistivity in the sample annealed at 1000 °C is assigned to both of the Zni related defects and the electrically activated Al donor. A new PL emission appears at around 3.32 eV after annealing at 1000 °C, suggesting electrically activated Al donors.

Single-step selection of drug resistant Acinetobacter baylyi ADP1 mutants reveals a functional redundancy in the recruitment of multidrug efflux systems.

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Anthony J Brzoska

Full Text Available Members of the genus Acinetobacter have been the focus recent attention due to both their clinical significance and application to molecular biology. The soil commensal bacterium Acinetobacter baylyi ADP1 has been proposed as a model system for molecular and genetic studies, whereas in a clinical environment, Acinetobacter spp. are of increasing importance due to their propensity to cause serious and intractable systemic infections. Clinically, a major factor in the success of Acinetobacter spp. as opportunistic pathogens can be attributed to their ability to rapidly evolve resistance to common antimicrobial compounds. Whole genome sequencing of clinical and environmental Acinetobacter spp. isolates has revealed the presence of numerous multidrug transporters within the core and accessory genomes, suggesting that efflux is an important host defense response in this genus. In this work, we used the drug-susceptible organism A. baylyi ADP1 as a model for studies into the evolution of efflux mediated resistance in genus Acinetobacter, due to the high level of conservation of efflux determinants across four diverse Acinetobacter strains, including clinical isolates. A single exposure of therapeutic concentrations of chloramphenicol to populations of A. baylyi ADP1 cells produced five individual colonies displaying multidrug resistance. The major facilitator superfamily pump craA was upregulated in one mutant strain, whereas the resistance nodulation division pump adeJ was upregulated in the remaining four. Within the adeJ upregulated population, two different levels of adeJ mRNA transcription were observed, suggesting at least three separate mutations were selected after single-step exposure to chloramphenicol. In the craA upregulated strain, a T to G substitution 12 nt upstream of the craA translation initiation codon was observed. Subsequent mRNA stability analyses using this strain revealed that the half-life of mutant craA mRNA was significantly

Coupled stress-strain and electrical resistivity measurements on copper based shape memory single crystals

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Gonzalez Cezar Henrique

2004-01-01

Full Text Available Recently, electrical resistivity (ER measurements have been done during some thermomechanical tests in copper based shape memory alloys (SMA's. In this work, single crystals of Cu-based SMA's have been studied at different temperatures to analyse the relationship between stress (s and ER changes as a function of the strain (e. A good consistency between ER change values is observed in different experiments: thermal martensitic transformation, stress induced martensitic transformation and stress induced reorientation of martensite variants. During stress induced martensitic transformation (superelastic behaviour and stress induced reorientation of martensite variants, a linear relationship is obtained between ER and strain as well as the absence of hys teresis. In conclusion, the present results show a direct evidence of martensite electrical resistivity anisotropy.

Fluoroquinolone Resistance Mechanisms in an Escherichia coli Isolate, HUE1, Without Quinolone Resistance-Determining Region Mutations

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Toyotaka eSato

2013-05-01

Full Text Available Fluoroquinolone resistance can cause major clinical problems. Here, we investigated fluoroquinolone resistance mechanisms in a clinical Escherichia coli isolate, HUE1, which had no mutations quinolone resistance-determining regions (QRDRs of DNA gyrase and topoisomerase IV. HUE1 demonstrated MICs that exceeded the breakpoints for ciprofloxacin, levofloxacin, and norfloxacin. HUE1 harbored oqxAB and qnrS1 on distinct plasmids. In addition, it exhibited lower intracellular ciprofloxacin concentrations and higher mRNA expression levels of efflux pumps and their global activators than did reference strains. The genes encoding AcrR (local AcrAB repressor and MarR (MarA repressor were disrupted by insertion of the transposon IS3-IS629 and a frameshift mutation, respectively. A series of mutants derived from HUE1 were obtained by plasmid curing and gene knockout using homologous recombination. Compared to the MICs of the parent strain HUE1, the fluoroquinolone MICs of these mutants indicated that qnrS1, oqxAB, acrAB, acrF, acrD, mdtK, mdfA, and tolC contributed to the reduced susceptibility to fluoroquinolone in HUE1. Therefore, fluoroquinolone resistance in HUE1 is caused by concomitant acquisition of QnrS1 and OqxAB and overexpression of AcrAB−TolC and other chromosome-encoded efflux pumps. Thus, we have demonstrated that QRDR mutations are not absolutely necessary for acquiring fluoroquinolone resistance in E. coli.

Factors determining sensitivity or resistance of tumor cell lines towards artesunate.

Science.gov (United States)

Sertel, Serkan; Eichhorn, Tolga; Sieber, Sebastian; Sauer, Alexandra; Weiss, Johanna; Plinkert, Peter K; Efferth, Thomas

2010-04-15

Clinical oncology is still challenged by the development of drug resistance of tumors that result in poor prognosis for patients. There is an urgent necessity to understand the molecular mechanisms of resistance and to develop novel therapy strategies. Artesunate (ART) is an anti-malarial drug, which also exerts profound cytotoxic activity towards cancer cells. We first applied a gene-hunting approach using cluster and COMPARE analyses of microarray-based transcriptome-wide mRNA expression profiles. Among the genes identified by this approach were genes from diverse functional groups such as structural constituents of ribosomes (RPL6, RPL7, RPS12, RPS15A), kinases (CABC1, CCT2, RPL41), transcriptional and translational regulators (SFRS2, TUFM, ZBTB4), signal transducers (FLNA), control of cell growth and proliferation (RPS6), angiogenesis promoting factors (ITGB1), and others (SLC25A19, NCKAP1, BST1, DBH, FZD7, NACA, MTHFD2). Furthermore, we applied a candidate gene approach and tested the role of resistance mechanisms towards established anti-cancer drugs for ART resistance. By using transfected or knockout cell models we found that the tumor suppressor p16(INK4A) and the anti-oxidant protein, catalase, conferred resistance towards ART, while the oncogene HPV-E6 conferred sensitivity towards ART. The tumor suppressor p53 and its downstream protein, p21, as well as the anti-oxidant manganese-dependent superoxide dismutase did not affect cellular response to ART. In conclusion, our pharmacogenomic approach revealed that response of tumor cells towards ART is multi-factorial and is determined by gene expression associated with either ART sensitivity or resistance. At least some of the functional groups of genes (e.g. angiogenesis promoting factors, cell growth and proliferation-associated genes signal transducers and kinases) are also implicated in clinical responsiveness of tumors towards chemotherapy. It merits further investigation, whether ART is responsive in

Single- and multistep resistance selection studies on the activity of retapamulin compared to other agents against Staphylococcus aureus and Streptococcus pyogenes.

Science.gov (United States)

Kosowska-Shick, Klaudia; Clark, Catherine; Credito, Kim; McGhee, Pamela; Dewasse, Bonifacio; Bogdanovich, Tatiana; Appelbaum, Peter C

2006-02-01

Retapamulin had the lowest rate of spontaneous mutations by single-step passaging and the lowest parent and selected mutant MICs by multistep passaging among all drugs tested for all Staphylococcus aureus strains and three Streptococcus pyogenes strains which yielded resistant clones. Retapamulin has a low potential for resistance selection in S. pyogenes, with a slow and gradual propensity for resistance development in S. aureus.

A measurement method for determination of dc internal resistance of batteries and supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Zhao, Shuhong; Wu, Feng [Department of Materials Science, Beijing Science and Technology University, Beijing 100081 (China); Yang, Liuxiang; Gao, Lijun [Department of Chemistry, NanChang University, JiangXi 330031 (China); Burke, Andrew F. [Institute of Transportation, University of California, Davis, CA 95616 (United States)

2010-02-15

Internal resistance is an importance parameter determining the power performance of a battery or supercapacitor. An 8.5 Ah Li-ion battery and a 350 F supercapacitor were tested as examples to validate the measurement method of dc internal resistance. Voltage data were taken at 10 ms, 2 s and 30 s after the current interruption or pulse. The ac resistances at 1 kHz of the battery and supercapacitor were also measured for comparison with the dc values. Based on these tests, it is proposed that the dc internal resistance of the battery and supercapacitor be obtained from {delta}V/{delta}I where the {delta}V is the voltage change after the current interruption, and {delta}I means current change from I to 0. When the voltage change at 10 ms or less is selected, the resistance corresponds to the Ohmic resistance of the device. (author)

Determination of D10 values of single and mixed cultures of bacteria after gamma irradiation

International Nuclear Information System (INIS)

Adu-Gyamfi, A.; Nketsia-Tabiri, J.; Boatin, R.

2009-01-01

The D 10 value of bacteria represents the absorbed radiation dose required to inactivate 90 % of a viable population or reduce the population by a factor of 10. D 10 values of 3 bacterial isolates (Escherichia coli, Staphylococcus aureus and Salmonella parathyphi B) were determined using single and mixed cultures to assess the effect of microbial competition on radiosensitivity. The isolates were inoculated into wakye substrate and exposed to γ-radiation doses of 0, 100, 300, 450, 600, 750, 850 Gy from a 6O Co source at a dose rate of 2.20 kGy/h in air. Enumeration of survivors of the isolates was carried out using serial dilution and pour plate methods. The surviving fraction of isolates decreased with increased irradiation doses. D 10 values of E. coli, S. aureus and S. parathyphi B were respectively 0.27, 0.33 and 0.44 kGy when inoculated as single cultures, and 0.24, 0.28 and 0.32 kGy respectively when inoculated as mixed cultures. D 10 values were lower for mixed cultures compared to single cultures, which might indicate reduced resistance to γ-radiation as a result of competition among the isolates. Microbiological challenge tests based on the D 10 values may result in delivery of higher irradiation doses, but the extra dose could serve as safety margin to enhance the food preservative capacity of radiation processing. (au)

Ion beam modification of thermal stress resistance of MgO single crystals with different crystallographic faces

International Nuclear Information System (INIS)

Gurarie, V.N.; Otsuka, P.H.; Williams, J.S.; Conway, M.J.

2000-01-01

Ion beam modification of thermal shock stress resistance of MgO single crystals with various crystallographic faces is investigated. The most stable crystal faces in terms of stress and damage resistance are established. Ion implantation is shown to reduce the temperature threshold of fracture for all crystal faces tested. The (111) face is demonstrated to be of highest stability compared to (110) and (100) faces in both implanted and unimplanted crystals. At the same time ion implantation substantially increases the microcrack density for all the faces tested and reduces the degree of fracture damage following thermal shock. The theoretical resistance parameters for various crystal faces are calculated using the continuum mechanics approach. The results are discussed on the basis of fracture mechanics principles and the effect of the implantation-induced lattice damage on crack nucleation

76 FR 60448 - Syngenta Biotechnology, Inc.; Determination of Nonregulated Status for Lepidopteran-Resistant Cotton

Science.gov (United States)

2011-09-29

...] Syngenta Biotechnology, Inc.; Determination of Nonregulated Status for Lepidopteran-Resistant Cotton AGENCY... our determination that a cotton line developed by Syngenta Biotechnology, Inc., designated as event... submitted by Syngenta Biotechnology, Inc., in its petition for a determination of nonregulated status, our...

Single mode solid state distributed feedback dye laser fabricated by grey scale electron beam lithography on dye doped SU-8 resist

DEFF Research Database (Denmark)

Balslev, Søren; Rasmussen, Torben; Shi, Peixiong

2005-01-01

We demonstrate grey scale electron beam lithography on functionalized SU-8 resist for fabrication of single mode solid state dye laser devices. The resist is doped with Rhodamine 6G perchlorate and the lasers are based on a first order Bragg grating distributed feedback resonator. The lasers...

Antibiotic Resistance Determinant-Focused Acinetobacter baumannii Vaccine Designed Using Reverse Vaccinology.

Science.gov (United States)

Ni, Zhaohui; Chen, Yan; Ong, Edison; He, Yongqun

2017-02-21

As one of the most influential and troublesome human pathogens, Acinetobacter baumannii ( A. baumannii ) has emerged with many multidrug-resistant strains. After collecting 33 complete A. baumannii genomes and 84 representative antibiotic resistance determinants, we used the Vaxign reverse vaccinology approach to predict classical type vaccine candidates against A. baumannii infections and new type vaccine candidates against antibiotic resistance. Our genome analysis identified 35 outer membrane or extracellular adhesins that are conserved among all 33 genomes, have no human protein homology, and have less than 2 transmembrane helices. These 35 antigens include 11 TonB dependent receptors, 8 porins, 7 efflux pump proteins, and 2 fimbrial proteins (FilF and CAM87009.1). CAM86003.1 was predicted to be an adhesin outer membrane protein absent from 3 antibiotic-sensitive strains and conserved in 21 antibiotic-resistant strains. Feasible anti-resistance vaccine candidates also include one extracellular protein (QnrA), 3 RND type outer membrane efflux pump proteins, and 3 CTX-M type β-lactamases. Among 39 β-lactamases, A. baumannii CTX-M-2, -5, and -43 enzymes are predicted as adhesins and better vaccine candidates than other β-lactamases to induce preventive immunity and enhance antibiotic treatments. This report represents the first reverse vaccinology study to systematically predict vaccine antigen candidates against antibiotic resistance for a microbial pathogen.

Determining the fracture resistance of advanced SiC fiber reinforced SiC matrix composites

International Nuclear Information System (INIS)

Nozawa, T.; Katoh, Y.; Kishimoto, H.

2007-01-01

Full text of publication follows: One of the perceived advantages for highly-crystalline and stoichiometric silicon carbide (SiC) and SiC composites, e.g., advanced SiC fiber reinforced chemically-vapor-infiltrated (CVI) SiC matrix composites, is the retention of fast fracture properties after neutron irradiation at high-temperatures (∼1000 deg. C) to intermediate-doses (∼15 dpa). Accordingly, it has been clarified that the maximum allowable stress (or strain) limit seems unaffected in certain irradiation conditions. Meanwhile, understanding the mechanism of crack propagation from flaws, as potential weakest link to cause composite failure, is somehow lacking, despite that determining the strength criterion based on the fracture mechanics will eventually become important considering the nature of composites' fracture. This study aims to evaluate crack propagation behaviors of advanced SiC/SiC and to provide fundamentals on fracture resistance of the composites to define the strength limit for the practical component design. For those purposes, the effects of irreversible energies related to interfacial de-bonding, fiber bridging, and microcrack forming on the fracture resistance were evaluated. Two-dimensional SiC/SiC composites were fabricated by CVI or nano-infiltration and transient-eutectic-phase (NITE ) methods. Hi-Nicalon TM Type-S or Tyranno TM -SA fibers were used as reinforcements. In-plane mode-I fracture resistance was evaluated by the single edge notched bend technique. The key finding is the continuous Load increase with the crack growth for any types of advanced composites, while many studies specified the gradual load decrease for the conventional composites once the crack initiates. This high quasi-ductility appeared due primarily to high friction (>100 MPa) at the fiber/matrix interface using rough SiC fibers. The preliminary analysis based on the linear elastic fracture mechanics, which does not consider the effects of irreversible energy

System and method for determining stator winding resistance in an AC motor

Science.gov (United States)

Lu, Bin [Kenosha, WI; Habetler, Thomas G [Snellville, GA; Zhang, Pinjia [Atlanta, GA; Theisen, Peter J [West Bend, WI

2011-05-31

A system and method for determining stator winding resistance in an AC motor is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of an AC motor. The circuit includes at least one contactor and at least one switch to control current flow and terminal voltages in the AC motor. The system also includes a controller connected to the circuit and configured to modify a switching time of the at least one switch to create a DC component in an output of the system corresponding to an input to the AC motor and determine a stator winding resistance of the AC motor based on the injected DC component of the voltage and current.

Nickel-resistance determinants in Acidiphilium sp. PM identified by genome-wide functional screening.

Directory of Open Access Journals (Sweden)

Patxi San Martin-Uriz

Full Text Available Acidiphilium spp. are conspicuous dwellers of acidic, metal-rich environments. Indeed, they are among the most metal-resistant organisms; yet little is known about the mechanisms behind the metal tolerance in this genus. Acidiphilium sp. PM is an environmental isolate from Rio Tinto, an acidic, metal-laden river located in southwestern Spain. The characterization of its metal resistance revealed a remarkable ability to tolerate high Ni concentrations. Here we report the screening of a genomic library of Acidiphilium sp. PM to identify genes involved in Ni resistance. This approach revealed seven different genes conferring Ni resistance to E. coli, two of which form an operon encoding the ATP-dependent protease HslVU (ClpQY. This protease was found to enhance resistance to both Ni and Co in E. coli, a function not previously reported. Other Ni-resistance determinants include genes involved in lipopolysaccharide biosynthesis and the synthesis of branched amino acids. The diversity of molecular functions of the genes recovered in the screening suggests that Ni resistance in Acidiphilium sp. PM probably relies on different molecular mechanisms.

Radiation resistance characteristics of optical communication system for single mode

International Nuclear Information System (INIS)

Ohe, Masamoto; Chigusa, Yoshiki; Kyodo, Tomohisa; Tanaka, Gohtaro; Watanabe, Hajime; Okamoto, Shin-ichi; Yamamoto, Takao.

1988-01-01

Optical communication has been utilized also for nuclear power stations and fuel reporocessing plants. As the sufficient safety countermeasures are required there, the amount of information becomes enormous, therefore, optical communication, by which the required space is expected to be reduced, becomes more important. Also in the application to submarine cables, attention must be paid to the radiation resistance as there are the effects of potassium contained in large amount in seawater and uranium deposits in sea bottom. Therefore, the reliability of the components of optical communication systems against radiation becomes a problem. In this study, single mode optical fibers and transmission and receipt modules were selected, and high dose rate irradiation supposing the case of using in a cell and low dose rate, long time irradiation supposing the case of submarine cables were carried out to evaluate the radiation resistance characteristics. The fibers tested were SiO 2 core/F-SiO 2 clad type and GeO 2 -SiO 2 core/SiO 2 clad type. The characteristics of increasing loss in irradiation and restoration after irradiation of the former type were superior to those of the latter type. The output of a receipt module was normal during irradiation, and the output power of a transmission module decreases, but other problems did not arise. (K.I.)

Comparative Analysis of Three Methods for Determination of Imipenem Resistance in Pseudomonas aeruginosa

Directory of Open Access Journals (Sweden)

Tanaz Zabihi

2016-02-01

Full Text Available "> Background: These days, the antibiotic resistance of Pseudomonas aeruginosa isolates toimipenem has significantly increased. Therefore the study of resistance to imipenem in thisorganism to imipenem in determining the appropriate treatment is crucial and necessary. The goalof this study is to compare three phenotypic methods of E-test, disk diffusion and micro brothdilution in the study of resistance to imipenem in clinical isolates of P. aeruginosa.Methods: Within a 6-month interval, 120 clinical specimens were collected and evaluated. Allisolates were identified as P. aeruginosa by standard biochemical tests and amplification of 16SrRNA gene. Three phenotypic methods of E-test, disk diffusion, and micro broth dilution wereused to determine imipenem resistance in P. aeruginosa isolates.Results: Of the 96 P. aeruginosa isolates studied for their resistance to imipenem by the use ofE-test, disk diffusion and micro broth dilution methods, 38.5% of the strains in micro broth dilutionmethod and 33.3% in the two methods of E-test and disk diffusion were resistant to imipenem. Therate of sensitivity and specificity of disk diffusion and E-test methods were 100%, 90.1%, and theywere 100% and 83.1% for micro broth dilution, respectively.Conclusions: With regard to the results obtained from the comparison of the three methods100% agreement were observed among the antimicrobial susceptibility results obtained by the Etest and disk diffusion methods (P ≥ 0.05. Therefore, the use of disk diffusion method can bean appropriate replacement for E-test method with regard to its being easy and cost-effective.

Observation of negative differential resistance and single-electron tunneling in electromigrated break junctions

International Nuclear Information System (INIS)

Noguchi, Yutaka; Ueda, Rieko; Kubota, Tohru; Kamikado, Toshiya; Yokoyama, Shiyoshi; Nagase, Takashi

2008-01-01

We observed a negative differential resistance (NDR) along with single-electron tunneling (SET) in the electron transport of electromigrated break junctions with metal-free tetraphenylporphyrin (H 2 BSTBPP) at a temperature of 11 K. The NDR strongly depended on the applied gate voltages, and appeared only in the electron tunneling region of the Coulomb diamond. We could explain the mechanism of this new type of electron transport by a model assuming a molecular Coulomb island and local density of states of the source and the drain electrodes

Single layer and multilayer wear resistant coatings of (Ti,Al)N: a review

International Nuclear Information System (INIS)

PalDey, S.; Deevi, S.C.

2003-01-01

periodicity of 5-10 nm allow creation of coatings with different properties than PVD deposited single layered thick coatings with columnar grain structure. A range of (Ti,Al)N based multilayers containing layers of (Ti,Al)CN, (Ti,Nb)N, TiN, AlN/TiN, CrN, Mo and WC are also reviewed. It is now possible to design new wear resistant or functional coatings based on a multilayer or a multicomponent system to meet the demanding applications of advanced materials

Single or in Combination Antimicrobial Resistance Mechanisms of Klebsiella pneumoniae Contribute to Varied Susceptibility to Different Carbapenems

Science.gov (United States)

Tsai, Yu-Kuo; Liou, Ci-Hong; Fung, Chang-Phone; Lin, Jung-Chung; Siu, L. Kristopher

2013-01-01

Resistance to carbapenems has been documented by the production of carbapenemase or the loss of porins combined with extended-spectrum β-lactamases or AmpC β-lactamases. However, no complete comparisons have been made regarding the contributions of each resistance mechanism towards carbapenem resistance. In this study, we genetically engineered mutants of Klebsiella pneumoniae with individual and combined resistance mechanisms, and then compared each resistance mechanism in response to ertapenem, imipenem, meropenem, doripenem and other antibiotics. Among the four studied carbapenems, ertapenem was the least active against the loss of porins, cephalosporinases and carbapenemases. In addition to the production of KPC-2 or NDM-1 alone, resistance to all four carbapenems could also be conferred by the loss of two major porins, OmpK35 and OmpK36, combined with CTX-M-15 or DHA-1 with its regulator AmpR. Because the loss of OmpK35/36 alone or the loss of a single porin combined with bla CTX-M-15 or bla DHA-1-ampR expression was only sufficient for ertapenem resistance, our results suggest that carbapenems other than ertapenem should still be effective against these strains and laboratory testing for non-susceptibility to other carbapenems should improve the accurate identification of these isolates. PMID:24265784

Hydrostatic pressure (8 GPa) dependence of electrical resistivity of BaCo{sub 2}As{sub 2} single crystal

Energy Technology Data Exchange (ETDEWEB)

Ganguli, Chandreyee; Matsubayashi, Kazuyuki; Ohgushi, Kenya [Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Uwatoko, Yoshiya, E-mail: uwatoko@issp.u-tokyo.ac.jp [Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Kanagaraj, Moorthi [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620024 (India); Arumugam, Sonachalam, E-mail: sarumugam1963@yahoo.com [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620024 (India)

2013-10-15

Graphical abstract: - Highlights: • Single crystals of BaCo{sub 2}As{sub 2} were grown by CoAs self-flux method. • We have studied pressure effects (8 GPa) on dc electrical resistivity of BaCo{sub 2}As{sub 2}. • On applied external pressure BaCo{sub 2}As{sub 2} remains a metallic state up to 8 GPa. • Superconductivity is absent in BaCo{sub 2}As{sub 2} because of its proximity to ferromagnetism. - Abstract: The pressure dependence of the electrical resistivity of BaCo{sub 2}As{sub 2} single crystal as a function of temperature was measured at ambient and high pressures up to 8 GPa for the first time using cubic anvil high pressure cell. It is observed that at room temperature the resistivity monotonically decreases with increasing pressure and it remains in the metallic state even at an applied pressure of 8 GPa. From the temperature dependence of the resistivity measurements under pressure, we found that superconductivity is absent up to 8 GPa. The value of the electron's scattering factor (A) is found to be large at ambient pressure and it decreases with the application of pressure, indicating that the substantial electron correlation effect of BaCo{sub 2}As{sub 2} is reduced under pressure, revealing a dramatic change of density of states at the Fermi energy.

Acinetobacter baumannii Isolated from Lebanese Patients: Phenotypes and Genotypes of Resistance, Clonality, and Determinants of Pathogenicity.

Science.gov (United States)

Dahdouh, Elias; Hajjar, Micheline; Suarez, Monica; Daoud, Ziad

2016-01-01

Introduction: Acinetobacter baumannii is a nosocomial pathogen that usually affects critically ill patients. High mortality rates have been associated with MDR A. baumannii infections. Carbapenem resistance among these isolates is increasing worldwide and is associated with certain International Clones (ICs) and oxacillinases (OXAs). Moreover, this organism possesses a wide range of virulence factors, whose expression is not yet fully understood. In this study, clinical A. baumannii isolates are characterized in terms of antibiotic resistance, mechanisms of carbapenem resistance, clonality, and virulence. Materials and Methods: A. baumannii clinical isolates ( n = 90) where obtained from a tertiary care center in Beirut, Lebanon. API 20NE strips in addition to the amplification of bla OXA-51-like were used for identification. Antibiotic susceptibility testing by disk diffusion was then performed in addition to PCRs for the detection of the most commonly disseminated carbapenemases. Clonality was determined by tri-locus PCR typing and doubling times were determined for isolates with varying susceptibility profiles. Biofilm formation, hemolysis, siderophore production, proteolytic activity, and surface motility was then determined for all the isolates. Statistical analysis was then performed for the determination of associations. Results and Discussion: 81 (90%) of the isolates were resistant to carbapenems. These high rates are similar to other multi-center studies in the country suggesting the need of intervention on a national level. 74 (91.3%) of the carbapenem resistant isolates harbored bla OXA-23-like including two that also harbored bla OXA-24-like . 88.9% of the A. baumannii isolates pertained to ICII and three other international clones were detected, showing the wide dissemination of clones into geographically distinct locations. Virulence profiles were highly diverse and no specific pattern was observed. Nevertheless, an association between motility

Microdissection and molecular manipulation of single chromosomes in woody fruit trees with small chromosomes using pomelo (Citrus grandis) as a model. II. Cloning of resistance gene analogs from single chromosomes.

Science.gov (United States)

Huang, D; Wu, W; Lu, L

2004-05-01

Amplification of resistance gene analogs (RGAs) is both a useful method for acquiring DNA markers closely linked to disease resistance (R) genes and a potential approach for the rapid cloning of R genes in plants. However, the screening of target sequences from among the numerous amplified RGAs can be very laborious. The amplification of RGAs from specific chromosomes could greatly reduce the number of RGAs to be screened and, consequently, speed up the identification of target RGAs. We have developed two methods for amplifying RGAs from single chromosomes. Method 1 uses products of Sau3A linker adaptor-mediated PCR (LAM-PCR) from a single chromosome as the templates for RGA amplification, while Method 2 directly uses a single chromosomal DNA molecule as the template. Using a pair of degenerate primers designed on the basis of the conserved nucleotide-binding-site motifs in many R genes, RGAs were successfully amplified from single chromosomes of pomelo using both these methods. Sequencing and cluster analysis of RGA clones obtained from single chromosomes revealed the number, type and organization of R-gene clusters on the chromosomes. We suggest that Method 1 is suitable for analyzing chromosomes that are unidentifiable under a microscope, while Method 2 is more appropriate when chromosomes can be clearly identified.

The Effect of Single Portion Glutamine Supplement Consumption on Injury Indices of Muscle After Eccentric Resistance Exercise

Directory of Open Access Journals (Sweden)

Azadeh Najarzadeh

2015-07-01

Full Text Available Abstract Background: Delayed muscular soreness after resistance exercises or eccentric trainings is probably because of muscle damage and injury. Nutrition by playing a crucial role in both protein synthesize and catabolism can influence the extent of muscle injury. The objective of this study was to assess the effect of single portion of Glutamine supplement consumption on injury indices of muscle after a session eccentric resistance exercise. Materials and Methods: this study used a randomized, double blind design that consisted of 80 volvnteer non-athletic males (aged 22.2±2.2years, height 175±5 cm, weight 71/64±9 kg, body mass index 23/2±2/2 kg/m2, and body fat 17/5±2/4%. A total of 40 participants were divided randomly into 2 groups, supplement group (receiving 0/1 g/kg Body weight/ day Glutamine and placebo group (receiving 0/1 g/kg Body weight/ day Maltodextrin. Serum keratine kinase (CK was determined by photometric method, muscle pain and knee joint range of motion were measured using, respectively, a standard scale of PAS and goniometer before, 24 and 48 hours after a resistance test involving knee flexion. Results: Glutamine supplement consumption caused no significant differences in CK levels reduction in none of the measured times, but it reduced the muscle pain at the times of 24 and 48 hours in comparison with the placebo group. In addition, the knee joint range of motion was significantly improved at 24 hours after the test. Conclusion: It seems that this dose of Glutamine supplementation can reduce the apparent signs apart from muscle injury indices reduction.

Determinants of Intravascular Resistance in Indian Diabetic Nephropathy Patients: A Hospital-Based Study

Directory of Open Access Journals (Sweden)

Anubhav Thukral

2011-01-01

Full Text Available Aims and Objectives. Metabolic dysregulation has failed to explain clinical variability of patients with diabetic nephropathy and hence a renewed interest emerged in haemodynamic factors as determinant of progression and development of diabetic nephropathy. We therefore studied for various factors which can correlate with raised renal vascular resistance in diabetic nephropathy. Material and Methods. Renal vascular resistance was measured in patients with established and incipient diabetic nephropathy and compared with controls using noninvasive color Doppler examinations of intrarenal vasculature. Results. Renal vascular resistance correlated with age, duration of disease, GFR, serum creatinine, and stage of retinopathy. Renal vascular resistance was significantly reduced in patients on treatment with RAAS inhibitors and insulin, than those on OHA and antihypertensives other than RAAS inhibitors. Conclusion. The study implies that renal vascular resistance may help identify diabetics at high risk of developing nephropathy, and these set of patients could be candidates for RAAS inhibition and early insulin therapy even in patients without albuminuria.

Typing of Staphylococcus aureus in order to determine the spread of drug resistant strains inside and outside hospital environment.

Science.gov (United States)

Pobiega, Monika; Wójkowska-Mach, Jadwiga; Heczko, Piotr B

2013-01-01

Staphylococcus aureus is one of the most important etiological factors of both nosocomial and community-acquired infections. Multidrug-resistant S. aureus is frequently isolated nowadays. Antibiotics used on the hospital ward exert a selective pressure on the strains and favor resistant strains. Multidrug-resistant and highly virulent strains can spread not only within the hospital but also between hospitals. Numerous studies show a predominance of one clone on a specific territory. The spread of such dangerous clones to neighboring countries and the entire continent is possible. Typing methods are very useful in infection control and prevention. Modern methods which are based on sequencing are necessary in rationalizing of infection control programs. Typing of Staphylococcus aureus includes methods that allow to determine the spread of drug-resistant pathogens. 'Gold standard' is pulsed-field gel electrophoresis (PFGE), which relies on separating the DNA fragments after restriction cutting. MLST (Multi Locus Sequence Typing) is based on a comparison of"housekeeping" gene sequences controlling the basic cell functions. With the MLST method, it is possible to demonstrate a broad, international spread of the specific clones. However, for epidemiological investigations, MLST seems to be too time-consuming and expensive to be used as a basic typing tool. The complementary method is spa typing, based on the sequencing of short repetitive sequences of the polymorphic X region from the gene encoding protein A. This method can be used for studying molecular evolution of S. aureus, as well as for testing for hospital outbreaks. It is faster and cheaper than MLST. It is also necessary to subtype the elements responsible for methycillin resistance (SCCmec), which allows to distinguish MRSA (Methicillin-resistant Staphylococcus aureus) clones with a common ancestor, but different epidemiological origin. All of those methods have their specific advantages and disadvantages and

An algorithm to determine backscattering ratio and single scattering albedo

Digital Repository Service at National Institute of Oceanography (India)

Suresh, T.; Desa, E.; Matondkar, S.G.P.; Mascarenhas, A.A.M.Q.; Nayak, S.R.; Naik, P.

Algorithms to determine the inherent optical properties of water, backscattering probability and single scattering albedo at 490 and 676 nm from the apparent optical property, remote sensing reflectance are presented here. The measured scattering...

Design of a Negative Differential Resistance Circuit Element Using Single-Electron Transistors

Science.gov (United States)

Dixon, D. C.; Heij, C. P.; Hadley, P.; Mooij, J. E.

1998-03-01

Electronic circuit elements displaying negative differential resistance (NDR), such as tunnel diodes, have a wide variety of device applications, including oscillators, amplifiers, logic, and memory. We present a two-terminal device using two single-electron transistors (SET's) that demonstrates an NDR profile tuneable with gate voltages. If the capacitive coupling between the SET's is sufficiently larger than the junction capacitances, the device exhibits multiply-peaked NDR, allowing its use as a multi-valued digital element. We will also report recent experimental progress in measurements of such a device, fabricated using standard Al tunnel junctions, but with an additional overlap capacitor to allow the required inter-SET coupling.

Crystal Structure of the Substrate-Binding Domain from Listeria monocytogenes Bile-Resistance Determinant BilE

NARCIS (Netherlands)

Ruiz, Stephanie J.; Schuurman-Wolters, Gea K.; Poolman, Bert

2016-01-01

BilE has been reported as a bile resistance determinant that plays an important role in colonization of the gastrointestinal tract by Listeria monocytogenes, the causative agent of listeriosis. The mechanism(s) by which BilE mediates bile resistance are unknown. BilE shares significant sequence

GenoType HelicoDR test in the determination of antimicrobial resistance of Helicobacter pylori in Korea.

Science.gov (United States)

Lee, Jung Won; Kim, Nayoung; Nam, Ryoung Hee; Park, Ji Hyun; Choi, Yoon Jin; Kim, Jung Mogg; Kim, Joo Sung; Jung, Hyun Chae

2014-09-01

Antimicrobial resistance of Helicobacter pylori is most important factor in eradication success. GenoType HelicoDR test has been developed for rapid detection of antimicrobial resistance. The present study evaluated the clinical usefulness of GenoType HelicoDR test in Korea. To detect 23S rRNA for clarithromycin resistance and gyrA mutations for fluoroquinolone resistance, both DNA sequencing after minimal inhibitory test (MIC) and GenoType HelicoDR test were performed in H. pylori isolates from the gastric mucosa of 101 patients. The eradication results of clarithromycin and moxifloxacin-containing triple therapy were evaluated by the 23S rRNA and gyrA mutations. For 42 isolates with A2143G mutation by GenoType HelicoDR, 83.3% (35/42) of concordance rate was estimated with DNA sequencing method and 85.7% (36/42) for MIC test. For 43 isolates with N87K mutation by GenoType HelicoDR, 71.1% (31/43) of concordance rate was estimated with DNA sequencing and 88.4% (38/43) for MIC test. The sensitivity and specificity of GenoType HelicoDR test in determination of 23S rRNA mutation were 94.9% and 87.1%, and those of gyrA 98.2% and 80.0%. The sensitivity and specificity of GenoType HelicoDR test in determination of clarithromycin resistance based on MIC test were 55.0% and 80.0%, for fluoroquinolone 74.4% and 70.0%. GenoType HelicoDR test is useful to determine mutations responsible for clarithromycin or fluoroquinolone-containing eradication failure but has a limitation for the clinical applicability in determination of resistance.

Glyphosate-Resistant Goosegrass from Mississippi

Directory of Open Access Journals (Sweden)

Vijay K. Nandula

2013-05-01

Full Text Available A suspected glyphosate-resistant goosegrass [Eleusine indica (L. Gaertn.] population, found in Washington County, Mississippi, was studied to determine the level of resistance and whether the resistance was due to a point mutation, as was previously identified in a Malaysian population. Whole plant dose response assays indicated a two- to four-fold increase in resistance to glyphosate. Leaf disc bioassays based on a glyphosate-dependent increase in shikimate levels indicated a five- to eight-fold increase in resistance. Sequence comparisons of messenger RNA for epsps, the gene encoding the enzyme 5-enolpyruvylshikimate-3-phosphate synthase, from resistant and sensitive goosegrass, revealed a cytosine to thymine nucleotide change at position 319 in the resistant accessions. This single nucleotide polymorphism causes a proline to serine amino acid substitution at position 106 in 5-enolpyruvylshikimate-3-phosphate synthase. A real-time polymerase chain reaction assay using DNA probes specific for the nucleotide change at position 319 was developed to detect this polymorphism. Goosegrass from 42 locations were screened, and the results indicated that glyphosate-resistant goosegrass remained localized to where it was discovered. Pendimethalin, s-metolachlor, clethodim, paraquat and fluazifop controlled resistant goosegrass 93% to 100%, indicating that several control options for glyphosate-resistant goosegrass are available.

Impact of single room design on the spread of multi-drug resistant bacteria in an intensive care unit.

NARCIS (Netherlands)

Halaby, Teysir; Al Naiemi, Nashwan; Beishuizen, Bert; Verkooijen, Roel; Ferreira, José A; Klont, Rob; Vandenbroucke-Grauls, Christina

2017-01-01

Cross-transmission of nosocomial pathogens occurs frequently in intensive care units (ICU). The aim of this study was to investigate whether the introduction of a single room policy resulted in a decrease in transmission of multidrug-resistant (MDR) bacteria in an ICU.

On the difference between optically and electrically determined resistivity of ultra-thin titanium nitride films

NARCIS (Netherlands)

Van Hao, B.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.

2013-01-01

This work reports on the determination and comparison of the resistivity of ultra-thin atomic layer deposited titanium nitride films in the thickness range 0.65–20 nm using spectroscopic ellipsometry and electrical test structures. We found that for films thicker than 4 nm, the resistivity values

Exploration of genetically determined resistance against hepatitis C infection in high-risk injecting drug users.

Science.gov (United States)

Sugden, P B; Cameron, B; Luciani, F; Lloyd, A R

2014-08-01

Genetic resistance to specific infections is well recognized. In hepatitis C virus (HCV) infection, genetic polymorphisms in IL-28B and the killer cell immunoglobulin-like receptors (KIR) and their HLA class I ligands have been shown to affect clearance of the virus following infection. There are limited data regarding resistance to established HCV infection. Reliable quantification of repeated exposure in high-risk populations, such as injecting drug users (IDU), is a key limitation of previous studies of resistance. Behavioural data and DNA from IDU (n = 210) in the Hepatitis C Incidence and Transmission Study in prisons (HITS-p) cohort were genotyped for polymorphisms in: IL-28B, peptidyl-prolyl isomerase A (PPIA), HLA-C and KIR2. To quantify risk, a composite risk index based on factors predictive of incident HCV infection was derived. Logistic regression analysis revealed the risk index was strongly associated with incident HCV infection (P C1, or their combination. A framework for the investigation of genetic determinants of resistance to HCV infection has been developed. Several candidate gene associations were investigated and excluded. Further investigation of genetic determinants of resistance to HCV infection is warranted. © 2014 John Wiley & Sons Ltd.

The effect of oxygen-doping on the electrical resistivity of vanadium

International Nuclear Information System (INIS)

Lang, E.; Bressers, J.

1975-01-01

High-purity vanadium single crystals characterized by resistance ratios in the range of 1,100 were doped to different oxygen levels and their electrical resistivity increase was measured as a function of the oxygen concentration. In the temperature range investigated, 77 to 293 K, the Matthiessen rule is obeyed. The increase in electrical resistivity per atomic percent oxygen is shown to be 5.16 μΩcm. For the ideal resistivity ratio rhosub(i) (77 K)/rhosub(i) (293 K) a value of 0.116 could be determined. (orig.) [de

Inheritance and mechanism of resistance to herbicides inhibiting acetolactate synthase in Sonchus oleraceus L.

Science.gov (United States)

Boutsalis, P; Powles, S B

1995-07-01

A biotype of Sonchus oleraceus L. (Compositae) has developed resistance to herbicides inhibiting acetolactate synthase (ALS) following field selection with chlorsulfuron for 8 consecutive years. The aim of this study was to determine the inheritance and mechanism of resistance in this biotype. Determination of ALS activity and inhibition kinetics revealed that Km and Vmax did not vary greatly between the resistant and susceptible biotypes. ALS extracted from the resistant biotype was resistant to five ALS-inhibiting herbicides in an in vitro assay. ALS activity from the resistant biotype was 14 19, 2, 3 and 3 times more resistant to inhibition by chlorsulfuron, sulfometuron, imazethapyr, imazapyr and flumetsulam, respectively, than the susceptible biotype. Hybrids between the resistant and a susceptible biotype were produced, and inheritance was followed through the F1, F2 and F3 generations. F1 hybrids displayed a uniform intermediate level of resistance between resistant and susceptible parents. Three distinct phenotypes, resistant, intermediate and susceptible, were identified in the F2 generation following chlorsulfuron application. A segregation ratio of 1∶2∶1 was observed, indicative of the action of a single, nuclear, incompletely dominant gene. F3 families, derived from intermediate F2 individuals, segregated in a similar manner. Resistance to herbicides inhibiting ALS in this biotype of S. oleraceus is due to the effect of a single gene coding for a resistant form of the target enzyme, ALS.

Numerical Simulation of Yttrium Aluminum Garnet(YAG) Single Crystal Growth by Resistance Heating Czochralski(CZ) Method

Energy Technology Data Exchange (ETDEWEB)

You, Myeong Hyeon; Cha, Pil Ryung [Kookmin University, Seoul (Korea, Republic of)

2017-01-15

Yttrium Aluminum Garnet (YAG) single crystal has received much attention as the high power solid-state laser’s key component in industrial and medical applications. Various growth methods have been proposed, and currently the induction-heating Czochralski (IHCZ) growth method is mainly used to grow YAG single crystal. Due to the intrinsic properties of the IHCZ method, however, the solid/liquid interface has a downward convex shape and a sharp tip at the center, which causes a core defect and reduces productivity. To produce YAG single crystals with both excellent quality and higher yield, it is essential to control the core defects. In this study, using computer simulations we demonstrate that the resistance-heating CZ (RHCZ) method may avoid a downward convex interface and produce core defect free YAG single crystal. We studied the effects of various design parameters on the interface shape and found that there was an optimum combination of design parameter and operating conditions that produced a flat solid-liquid interface.

Research on resistance to sunflower broomrape: an integrated vision

Directory of Open Access Journals (Sweden)

Velasco Leonardo

2016-03-01

Full Text Available Sunflower broomrape (Orobanche cumana Wallr. parasitization on sunflower was first observed at the end of the 19th century and has continued since then jeopardizing sunflower cultivation in many areas of Europe and Asia. A distinctive characteristic of the O. cumana-sunflower parasitic system is that it is mainly governed by a gene-for-gene interaction. This determines complete resistance in the host controlled by dominant alleles at a single locus, which facilitates the management of the resistance for hybrid seed production. But on the other hand avirulence in the parasite is also controlled by dominant alleles at a single gene. Monogenic, dominant resistance exerts a strong selection pressure on the parasite that maximizes the probability of overcoming resistance mechanisms in a short period of time. This has in fact resulted in a number of physiological races that periodically surpass all the available resistance sources. The spread of populations to new areas and the subsequent hybridization between populations is another mechanism creating genetic diversity in sunflower broomrape and allegedly recombination of avirulences genes. After more than one century of coexistence, genetic resistance to broomrape in sunflower has to be focused under an integrated approach that considers not only the characterization of resistance mechanisms in the host, but also the genetic and physiological bases of avirulence in the parasite. From the perspective of genetic resistance in sunflower, most important is not relying only on single dominant genes, but following instead pyramiding strategies. These should give priority to combining complementary mechanisms of resistance under both qualitative (vertical and quantitative (horizontal genetic control. These aspects are discussed in the paper.

Standard practice for determining rail-to-Earth resistance

CERN Document Server

American Society for Testing and Materials. Philadelphia

1999-01-01

1.1 This practice covers the procedures necessary to follow for measuring resistance-to-earth of the running rails which are used as the conductors for returning the train operating current to the substation in electric mass transit systems. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Electrical resistivity anisotropy of osmium single crystals in the range 4,2 to 300 K

International Nuclear Information System (INIS)

Volkenshtejn, N.V.; Dyakina, V.P.; Dyakin, V.V.; Startsev, V.E.; Cherepanov, V.I.; Azhazha, V.M.; Kovtun, G.P.; Elenskij, V.A.; AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst.)

1981-01-01

Electrical resistivity and size effect anisotropies of pure osmium single crystals with rhosub(273.2/rhosub(4.2)2600 were investigated in the temperature range 4.2 to 300 K. It is found that the electrical resistivity anisotropy (αT)=rhosub( )/rhosub( ) is less than unit and has a maximum at T approximately 50 K; the size effect anisotropy (rho1)sub( )/(rho1)sub( ) is 0.39+-0.07 at T=4.2 K; at liquid helium temperature, the dependence of thin samples is controlled by the scattering of conduction electrons by the surface of the sample. The results are discussed for the specific shape of the Fermi surface geometry of osmium with an account for the scattering processes of conduction electrons by phonons and by surface of the sample

The determination of multiple resistance, inheritance and cytochrome P450 activity in bifenthrinresistant Tetranychus urticae Koch (Acari: Tetranychidae)

OpenAIRE

AY, Recep; YORULMAZ, Sibel

2010-01-01

In this study, multiple resistance, inheritance and cytochrome P450 enzyme activity were determined in Tetranychus urticae Koch (SAK) population after 20 selections for bifenthrin resistance. Selection study and LC50, 60 levels of SAK population of T. urticae were determined by dry film method. LC50 level of the SAK population selected twenty times with bifenthrin was increased from 984.49 to 11914.40 µl l-1 distiled water. Selected population showing 21.84 fold resistances was named ...

Managing anthelmintic resistance-Variability in the dose of drug reaching the target worms influences selection for resistance?

Science.gov (United States)

Leathwick, Dave M; Luo, Dongwen

2017-08-30

The concentration profile of anthelmintic reaching the target worms in the host can vary between animals even when administered doses are tailored to individual liveweight at the manufacturer's recommended rate. Factors contributing to variation in drug concentration include weather, breed of animal, formulation and the route by which drugs are administered. The implications of this variability for the development of anthelmintic resistance was investigated using Monte-Carlo simulation. A model framework was established where 100 animals each received a single drug treatment. The 'dose' of drug allocated to each animal (i.e. the concentration-time profile of drug reaching the target worms) was sampled at random from a distribution of doses with mean m and standard deviation s. For each animal the dose of drug was used in conjunction with pre-determined dose-response relationships, representing single and poly-genetic inheritance, to calculate efficacy against susceptible and resistant genotypes. These data were then used to calculate the overall change in resistance gene frequency for the worm population as a result of the treatment. Values for m and s were varied to reflect differences in both mean dose and the variability in dose, and for each combination of these 100,000 simulations were run. The resistance gene frequency in the population after treatment increased as m decreased and as s increased. This occurred for both single and poly-gene models and for different levels of dominance (survival under treatment) of the heterozygote genotype(s). The results indicate that factors which result in lower and/or more variable concentrations of active reaching the target worms are more likely to select for resistance. The potential of different routes of anthelmintic administration to play a role in the development of anthelmintic resistance is discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Faradic resistance of the electrode/electrolyte interface.

Science.gov (United States)

Mayer, S; Geddes, L A; Bourland, J D; Ogborn, L

1992-09-01

A new method is used to measure the direct-current (Faradic) resistance of a single electrode/electrolyte interface. The method employs a constant-current pulse and a potential-sensing electrode. By choosing a sufficiently long pulse duration, the voltage between the test and potential-sensing electrode exhibits a three-phase response. In the steady-state phase, the voltage measured is equal to the current flowing through the electrode Faradic resistance and the resistance of the electrolyte between the test and potential-sensing electrode. By measuring this latter resistance with a high-frequency sinusoidal alternating current, the voltage drop in the electrolyte is calculated and subtracted from the voltage measured between the test and potential-sensing electrode, thereby allowing calculation of the Faradic resistance. By plotting the reciprocal of the Faradic resistance against current density and fitting the data points to a third-order polynomial, it is possible to determine the zero-current density (Faradic) resistance. This technique was used to determine the Faradic resistance of electrodes (0.1 cm2) of stainless-steel, platinum, platinum-iridium and rhodium in 0.9 per cent NaCl at 25 degrees. The zero current Faradic resistance is lowest for platinum (30.3 k omega), slightly higher for platinum-iridium (47.6k omega), much higher for rhodium (111k omega) and highest for type 316 stainless-steel (345k omega). In all cases, the Faradic resistance decreases dramatically with increasing current density.

Diagnosis and Antibiotic Resistance Distribution in Children with Urinary Tract Infection: A Single Center Experience

Directory of Open Access Journals (Sweden)

Rahime Renda

2018-01-01

Full Text Available Background: Urinary tract infection is a common disease in childhood. The aim of this study was to determine the diagnostic performance of urinary analysis, assess the role of urine culture in determining its necessity and evaluate etiologic agents and antimicrobial resistance patterns in children with urinary tract infection.Methods: Our study was made by evaluating the patients who applied to the Antalya Research and Training Hospital- Turkey, between 2015 and 2017. A total 237 urine analysis and urine culture were retrospectively analyzed. Culture results were taken a reference for microscopic and chemical examination of urine and diagnostic accuracy of the test parameters, and the performance of urine analysis were calculated. The culture and antibiogram results were examined and antibiotic resistance with infectious agents frequency was evaluated.Results: The 42.4% of culture negative samples showed leukocyte esterase, nitrite, bacterial and leukocyte counts, which are indicative of infection in urine analysis, were found in normal range. The highest sensitivity (90% was in the presence of leucocyte esterase and bacteria, while the highest specificity (99.4% was in the presence of nitrite alone or with other components (leucocyte or leucocyte esterase. The highest antibiotic resistance was found in beta lactam antibiotics. The lowest antibiotic resistance was detected in the carbapenem followed by fluoroquinolone group antibiotics.Conclusion: Microscopic and chemical examination of urine analysis can give us information about urine culture requirement. The observation of increasing overall resistance to antibiotics authorize further studies that lead to new recommendations to antibiotic use in children and adolescents.

Determination Pattern of Antibiotic Resistance in Entropathogenic Escherichia coli Strains Isolated from Children with Diarrhea

Directory of Open Access Journals (Sweden)

P. Karami

2012-04-01

Full Text Available Introduction & Objective: Diarrheal diseases are considered a major health problem, especially in children. Enteropathogenic Escherichia coli (EPEC strains are the common cause of diarrhea in children especially in developing countries. Because of undesirable effects of diarrhea and its interference with children's growth, in some cases antibiotic treatment is recommended. In recent years, resistance toward common and effective antibiotics in the treatment of infectious diseases became one of the most important challenges in medical society, for this purpose, antibiotic sensitivity and resistance of strains in every geographical zone must be determined. So in this study, of antibiotic patterns of these bacteria were examined.Materials & Methods: This cross-sectional study was performed on 192 strains of Enteropathogen Escherichia coli isolated from children who were suffering from diarrhea in 1389-1390 in the microbiology laboratory of Hamadan University of medical sciences. To identify these strains, standard biochemical and serology tests were used. The antibiotic sensitivity test of these isolates was carried out with disc diffusion agar method according to the CLSI standards for 14 different antibiotics disc. Resistance toward 3 or more than 3 classes of antibiotics were defined as multidrug resistance.Results: The result of this study shows EPEC strains had the highest resistance to cefpodoxime (97%, trimethoprim (60.7%, tetracycline (58.4% and ampicillin (45.8%. Multidrug resistance was 68.7 percent. These strains also showed the highest sensitivity against imipenem, ceftriaxone, and ciprofloxacin antibiotics.Conclusion: EPEC strains that were studied with resistance to ampicillin, tetracycline and convenient sensitivity against fluoroquinolones are one of the major factors in children’s diarrhea. A result of this research suggests that antimicrobial resistance in Escherichia coli strains are high and prescribing and antibiotic is not

Line-focus acoustic microscopy of Ti-6242 α/β single colony: determination of elastic constants

International Nuclear Information System (INIS)

Kim, J.-Y.; Yakovlev, V.; Rokhlin, S.I.

2002-01-01

Time-resolved line-focus acoustic microscopy is performed for determining elastic constants of Ti-6242 α/β-single colony and Ti-6 α-phase single crystal. Surface acoustic wave (SAW) velocities are obtained as a function of the propagation angle from measured time-delays of SAW signals. The propagation of surface waves in a semi-infinite half space formed by anisotropic layers inclined arbitrarily to the sample surface is studied to model a quasi-random lamellar structure of the Ti-6242 α/β-single colony. Effective elastic constants of the multilayered structure are derived and verified through the comparison with exact ones, based on which SAW velocities in non-principal planes are calculated. Effective and constituent elastic constants of the α/β-single colony and the α-phase single crystal are inversely determined from the measured and calculated SAW velocities. The α- and β-phase elastic constants from the α/β-single colony so determined are compared with those from the α-single crystal and data in the literature

Determination of response time of resistance thermometers by in situ measurements

International Nuclear Information System (INIS)

Goncalves, I.M.P.; Soares, A.J.

1986-01-01

The loop-current-step-response test provides a mean for determining the time constant of resistance thermometers. The test consists in heating the sensor a few degrees above ambient temperature by causing a step perurbation in the electric current that flows through the sensor leads. The developed mathematical transformation permits to use data collected during the internal heating transient to predict the sensor response to perturbations in fluid temperature. Experimental data obtained show that time constant determined by this method is within 15 percent of the true value. (Author) [pt

Single nucleotide polymorphisms in i-type lysozyme gene and their correlation with vibrio-resistance and growth of clam Meretrix meretrix based on the selected resistance stocks.

Science.gov (United States)

Yue, Xin; Wang, Hongxia; Huang, Xiaohong; Wang, Chao; Chai, Xueliang; Wang, Chunde; Liu, Baozhong

2012-09-01

I-type lysozyme is considered to play crucial roles in both anti-bacteria and digestion function of the bivalve, which signifies that it is related to both immunity and growth. In this study, based on the principle of case-control association analysis, using the stock materials with different vibrio-resistance profile obtained by selective breeding, single nucleotide polymorphisms (SNPs) in the DNA partial sequence of an i-type lysozyme of Meretrix meretrix (MmeLys) were discovered and examined for their association with vibrio-resistance and growth. Twenty-seven SNPs were detected and fifteen of them were genotyped in clam stocks with different resistance to Vibrio harveyi (09-C and 09-R) and to Vibrio parahaemolyticus (11-S and 11-R). Allele frequency distribution among different stocks was compared. And wet weight of clams with different genotype at each SNP locus was compared. The results indicated that SNP locus 9 was associated with V. harveyi and V. parahaemolyticus resistance and growth of M. meretrix. Loci 12 and 14 were associated with both V. parahaemolyticus-resistance and growth, and also have the potential to be related with V. harveyi-resistance of M. meretrix. Therefore these three SNPs especially locus 9 were the potential markers which may be involved in assisting resistance selective breeding. In addition, this study showed evidence that improvements in clam resistance to vibriosis could be achieved through selective breeding. All results provided encouragement for the continuation of the selective breeding program for vibrio-resistance gain in clam M. meretrix and the application of polymorphisms in MmeLys to the future marker assisted selection. Copyright © 2012 Elsevier Ltd. All rights reserved.

Distribution of extended-spectrum cephalosporin resistance determinants in Salmonella enterica and Escherichia coli isolated from broilers in southern Japan.

Science.gov (United States)

Shahada, F; Chuma, T; Kosugi, G; Kusumoto, M; Iwata, T; Akiba, M

2013-06-01

This study was conducted to investigate the distribution and diversity of extended-spectrum cephalosporin (ESC) resistance determinants in Salmonella enterica and Escherichia coli obtained from the same cecal samples and to provide evidence of transmission of the resistance determinants among these bacteria in broiler farms in southern Japan. Salmonella enterica and E. coli were characterized by serotyping and multilocus sequence typing, respectively. An antimicrobial susceptibility test, plasmid analysis, and identification and localization of resistance genes were performed to determine the relatedness of ESC resistance determinants among the isolates. Of 48 flocks examined, 14 had S. enterica. In total, 57 S. enterica isolates were obtained, 45 of which showed ESC resistance. Extended-spectrum cephalosporin-resistant E. coli were also obtained from all of these ESC-resistant Salmonella-positive samples. β-Lactamase genes, blaTEM-52 (38 isolates), blaCTX-M-14 (1 isolate), and blaCMY-2 (6 isolates), were carried by conjugative untypable or IncP plasmids detected in the S. enterica serovars Infantis and Manhattan. The β-lactamase genes blaCTX-M-14 (3 isolates), blaCTX-M-15 (3 isolates), blaSHV-2 (1 isolate), blaSHV-12 (2 isolates), and blaCMY-2 (32 isolates) associated with IncI1-Iγ, IncFIB, IncFIC, IncK, IncB/O, and IncY plasmids were detected in E. coli co-isolates. Restriction mapping revealed similar plasmids in Salmonella Infantis and Salmonella Manhattan and in different sequence types of E. coli. Intraspecies transmission of plasmids was suggested within S. enterica and E. coli populations, whereas interspecies transmission was not observed. This study highlights the importance of plasmids as carriers of ESC resistance determinants.

Microstructural evolution and mechanical performance of resistance spot welded DP1000 steel with single and double pulse welding

NARCIS (Netherlands)

Chabok, Ali; van der Aa, Ellen; De Hosson, Jeff; Pei, Yutao T.

2017-01-01

Two welding schemes of single and double pulse were used for the resistance spot welding of DP1000 dual phase steel. The changes in the mechanical performance and variant pairing of martensite under two different welding conditions were scrutinized. It is demonstrated that, although both welds fail

Insulin Sensitivity Determines Effects of Insulin and Meal Ingestion on Systemic Vascular Resistance in Healthy Subjects.

Science.gov (United States)

Woerdeman, Jorn; Meijer, Rick I; Eringa, Etto C; Hoekstra, Trynke; Smulders, Yvo M; Serné, Erik H

2016-01-01

In addition to insulin's metabolic actions, insulin can dilate arterioles which increase blood flow to metabolically active tissues. This effect is blunted in insulin-resistant subjects. Insulin's effect on SVR, determined by resistance arterioles, has, however, rarely been examined directly. We determined the effects of both hyperinsulinemia and a mixed meal on SVR and its relationship with insulin sensitivity. Thirty-seven lean and obese women underwent a hyperinsulinemic-euglycemic clamp, and 24 obese volunteers underwent a mixed-meal test. SVR was assessed using CPP before and during hyperinsulinemia as well as before and 60 and 120 minutes after a meal. SVR decreased significantly during hyperinsulinemia (-13%; p Insulin decreased SVR more strongly in insulin-sensitive individuals (standardized β: -0.44; p = 0.01). In addition, SVR at 60 minutes after meal ingestion was inversely related to the Matsuda index (β: -0.39; p = 0.04) and the change in postprandial SVR was directly related to postprandial glycemia (β: 0.53; p insulin resistance. This suggests that resistance to insulin-induced vasodilatation contributes to regulation of vascular resistance. © 2015 John Wiley & Sons Ltd.

Pulsed-laser-deposited, single-crystalline Cu2O films with low resistivity achieved through manipulating the oxygen pressure

Science.gov (United States)

Liu, Xiaohui; Xu, Meng; Zhang, Xijian; Wang, Weiguang; Feng, Xianjin; Song, Aimin

2018-03-01

Low-resistivity, single-crystalline Cu2O films were realized on MgO (110) substrates through manipulating the oxygen pressure (PO2) of pulsed-laser deposition. X-ray diffraction and high resolution transmission electron microscopy measurements revealed that the films deposited at PO2 of 0.06 and 0.09 Pa were single phase Cu2O and the 0.09-Pa-deposited film exhibited the best crystallinity with an epitaxial relationship of Cu2O (110)∥MgO (110) with Cu2O (001)∥MgO (001). The pure phase Cu2O films exhibited higher transmittances and larger band gaps with an optical band gap of 2.56 eV obtained for the 0.09 Pa-deposited film. Hall-effect measurements demonstrated that the Cu2O film deposited at 0.09 Pa had the lowest resistivity of 6.67 Ω cm and highest Hall mobility of 23.75 cm2 v-1 s-1.

GNSS Single Frequency, Single Epoch Reliable Attitude Determination Method with Baseline Vector Constraint

Directory of Open Access Journals (Sweden)

Ang Gong

2015-12-01

Full Text Available For Global Navigation Satellite System (GNSS single frequency, single epoch attitude determination, this paper proposes a new reliable method with baseline vector constraint. First, prior knowledge of baseline length, heading, and pitch obtained from other navigation equipment or sensors are used to reconstruct objective function rigorously. Then, searching strategy is improved. It substitutes gradually Enlarged ellipsoidal search space for non-ellipsoidal search space to ensure correct ambiguity candidates are within it and make the searching process directly be carried out by least squares ambiguity decorrelation algorithm (LAMBDA method. For all vector candidates, some ones are further eliminated by derived approximate inequality, which accelerates the searching process. Experimental results show that compared to traditional method with only baseline length constraint, this new method can utilize a priori baseline three-dimensional knowledge to fix ambiguity reliably and achieve a high success rate. Experimental tests also verify it is not very sensitive to baseline vector error and can perform robustly when angular error is not great.

Measurement of Dynamic Resistance in Resistance Spot Welding

DEFF Research Database (Denmark)

Wu, Pei; Zhang, Wenqi; Bay, Niels

Through years, the dynamic resistance across the electrodes has been used for weld quality estimation and contact resistance measurement. However, the previous methods of determining the dynamic resistance were mostly based on measuring the voltage and current on the secondary side of the transfo......Through years, the dynamic resistance across the electrodes has been used for weld quality estimation and contact resistance measurement. However, the previous methods of determining the dynamic resistance were mostly based on measuring the voltage and current on the secondary side...... of the transformer in resistance welding machines, implying defects from induction noise and interference with the leads connected to the electrodes for measuring the voltage. In this study, the dynamic resistance is determined by measuring the voltage on the primary side and the current on the secondary side...

Tests for determining impact resistance and strength of glass used for nuclear waste disposal

International Nuclear Information System (INIS)

Bunnell, L.R.

1979-05-01

Tests are described for determining the impact resistance (Section A) and static tensile strength (Section B) of glasses containing simulated or actual nuclear wastes. This report describes the development and use of these tests to rank different glasses, to assess effects of devitrification, and to examine the effect of impact energy on resulting surface area. For clarity this report is divided into two sections, Impact Resistance and Tensile Strength

Inheritance of resistance to anti-microtubule dinitroaniline herbicides in an "intermediate" resistant biotype of Eleusine indica (Poaceae).

Science.gov (United States)

Zeng, L; Baird, W V

1999-07-01

Inheritance of resistance to the anti-microtubule dinitroaniline herbicides was investigated in a goosegrass biotype displaying an intermediate level of resistance (I). Reciprocal crosses were made between the I biotype and previously characterized susceptible (S) or resistant (R) biotypes. Eight F(1) hybrids were identified, and F(2) populations were produced by selfing. The dinitroaniline-herbicide response phenotype (DRP) of F(1) plants, and F(2) seedlings was determined using a root-growth bioassay. The DRP of F(1) plants of S × I was "susceptible" (i.e., identical to the S parental plants), and the DRP of F(1) plants of I × R was "intermediate" (i.e., identical to the I parental plants). Nonparental phenotypes were not observed in F(1) plants. Results indicated susceptibility to be dominant over intermediate resistance and intermediate resistance to be dominant over high resistance. Analysis of reciprocal crosses ruled out any role for cytoplasmic inheritance. When treated at the discriminating concentration (e.g., 0.28 ppm oryzalin), F(2) seedlings of S × I were classified as either S or I phenotype, and F(2) seedlings of I × R were classified as either I or R phenotype. Again, nonparental phenotypes were not observed. The 3:1 (S:I or I:R) segregation ratios in F(2) seedlings were consistent across all eight F(2) families. The results show that dinitroaniline herbicide resistance in the I biotype of goosegrass is inherited as a single, nuclear gene. Furthermore, it suggests that dinitroaniline resistance in goosegrass is controlled by three alleles at a single locus (i.e., Drp-S, Drp-i, and Drp-r).

Determining the Resistivity of Resistive Sheets Using Transmission Measurements

National Research Council Canada - National Science Library

Hyde, IV, Milo W

2006-01-01

In September 2005, radar cross section (RCS) measurements were made of resistive sheets, or R-cards, wrapped around a polystyrene foam cylinder to compare with a newly developed theoretical RCS prediction technique...

Genetically Determined Insulin Resistance is Characterized by Down-Regulation of Mitochondrial Oxidative Metabolism in Human Skeletal Muscle

DEFF Research Database (Denmark)

Kristensen, Jonas M; Skov, Vibe; Wojtaszewski, Jørgen

2010-01-01

Transcriptional profiling of skeletal muscle from patients with type 2 diabetes and high-risk individuals have demonstrated a co-ordinated down-regulation of oxidative phosphorylation (OxPhos) genes, suggesting a link between insulin resistance and mitochondrial dysfunction. However, whether...... mitochondrial dysfunction is a cause or consequence of insulin resistance remains to be clarified. In the present study, we tested the hypothesis that mitochondrial oxidative metabolism was down-regulated in skeletal muscle of patients with genetically determined insulin resistance. Skeletal muscle biopsies.......02), and complex V (ATP5B; p=0.005). Our data demonstrate that genetically determined insulin resistance is associated with a co-ordinated down-regulation of OxPhos components both at the transcriptional and translational level. These findings suggest that an impaired biological response to insulin in skeletal...

A single-center experience with abiraterone as treatment for metastatic castration-resistant prostate cancer

DEFF Research Database (Denmark)

Thortzen, Anita; Thim, Stine; Røder, Martin Andreas

2016-01-01

BACKGROUND: Continuous stimulation of the androgen receptor (AR) axis is a prerequisite for growth in castration-resistant prostate cancer (CRPC). Abiraterone acetate (AA) is a potent inhibitor of extracellular and intracellular androgen synthesis by inhibition of the CYP-17 enzyme system, which...... at Rigshospitalet, Denmark, and compare the results with phase III trial outcomes. MATERIAL AND METHODS: Single-centre, retrospective study including consecutive patients managed on AA for more than 2-year period. Treatment consisted of 1,000mg AA and 5mg prednisone twice daily. Outcomes of interest were prostate...

Non-destructive local determination of doping additions and main components in single crystals

International Nuclear Information System (INIS)

Ehksperiandova, L.P.; Blank, A.B.; Kukhtina, N.N.; Afanasiadi, L.I.

1994-01-01

Procedures for local non-destructive determination of elements in optical and scintillation single crystals are developed. They are applied for determination of the main components (in cadmium tungstate) and doping additions (tellurium in zinc selenide, europium in gadolinium silicate). The metrological characteristics of the developed micro-analysis methods are estimated. Segregation of the main components and doping additions in the objects under consideration are investigated. Tellurium is found to be distributed uniformly on the cross-sections of bulk zinc selenide single crystals. The segregation of europium along gadolinium silicate ingots is almost absent. On the cross-section surface of cadmium tungstate single crystals the microregions are found characterized by the prevailing contents of cadmium or tungsten

Determining Complex Structures using Docking Method with Single Particle Scattering Data

Directory of Open Access Journals (Sweden)

Haiguang Liu

2017-04-01

Full Text Available Protein complexes are critical for many molecular functions. Due to intrinsic flexibility and dynamics of complexes, their structures are more difficult to determine using conventional experimental methods, in contrast to individual subunits. One of the major challenges is the crystallization of protein complexes. Using X-ray free electron lasers (XFELs, it is possible to collect scattering signals from non-crystalline protein complexes, but data interpretation is more difficult because of unknown orientations. Here, we propose a hybrid approach to determine protein complex structures by combining XFEL single particle scattering data with computational docking methods. Using simulations data, we demonstrate that a small set of single particle scattering data collected at random orientations can be used to distinguish the native complex structure from the decoys generated using docking algorithms. The results also indicate that a small set of single particle scattering data is superior to spherically averaged intensity profile in distinguishing complex structures. Given the fact that XFEL experimental data are difficult to acquire and at low abundance, this hybrid approach should find wide applications in data interpretations.

Parasitic resistive switching uncovered from complementary resistive switching in single active-layer oxide memory device

Science.gov (United States)

Zhu, Lisha; Hu, Wei; Gao, Chao; Guo, Yongcai

2017-12-01

This paper reports the reversible transition processes between the bipolar and complementary resistive switching (CRS) characteristics on the binary metal-oxide resistive memory devices of Pt/HfO x /TiN and Pt/TaO x /TiN by applying the appropriate bias voltages. More interestingly, by controlling the amplitude of the negative bias, the parasitic resistive switching effect exhibiting repeatable switching behavior is uncovered from the CRS behavior. The electrical observation of the parasitic resistive switching effect can be explained by the controlled size of the conductive filament. This work confirms the transformation and interrelationship among the bipolar, parasitic, and CRS effects, and thus provides new insight into the understanding of the physical mechanism of the binary metal-oxide resistive switching memory devices.

Determinants of Growth Hormone Resistance in Malnutrition

Science.gov (United States)

Fazeli, Pouneh K.; Klibanski, Anne

2014-01-01

States of under-nutrition are characterized by growth hormone resistance. Decreased total energy intake, as well as isolated protein-calorie malnutrition and isolated nutrient deficiencies result in elevated growth hormone levels and low levels of IGF-I. We review various states of malnutrition and a disease state characterized by chronic under-nutrition -- anorexia nervosa -- and discuss possible mechanisms contributing to the state of growth hormone resistance, including FGF-21 and SIRT1. We conclude by examining the hypothesis that growth hormone resistance is an adaptive response to states of under-nutrition, in order to maintain euglycemia and preserve energy. PMID:24363451

Determinants of foamy virus envelope glycoprotein mediated resistance to superinfection

International Nuclear Information System (INIS)

Berg, Angelika; Pietschmann, Thomas; Rethwilm, Axel; Lindemann, Dirk

2003-01-01

Little is known about the nature of foamy virus (FV) receptor molecules on target cells and their interaction with the viral glycoproteins. Similar to other viruses, cellular expression of the FV Env protein is sufficient to induce resistance to exogenous FV, a phenomenon called superinfection resistance (SIR). In this study we define determinants of the FV Env protein essential for mediating SIR. FV Env requires the extracellular domains of the SU and the TM subunits as well as membrane anchorage, efficient cell surface transport, and most probably correct subunit processing. This is in contrast to murine leukemia virus where secreted proteins comprising the receptor-binding domain in SU are sufficient to induce SIR. Furthermore, we demonstrate that cellular expression of the prototype FV envelope proteins induces SIR against pseudotypes with glycoproteins of other FV species, including of simian, feline, bovine, and equine origin. This implies that all of them use the same receptor molecules for viral entry

Genetically determined differences in the resistance to myocardial infarction in Wistar and August rats.

Science.gov (United States)

Belkina, L M; Saltykova, V A; Pshennikova, M G

2001-06-01

In intact August rats, the cardiac contractile function at rest was by 76% higher than in Wistar rats, while their hearts, both intact and after acute myocardial infarction, were more resistant to isometric load than the hearts of Wistar rats. Postinfarction mortality in August rats was 18% vs. 70% in Wistar rats. Adrenoreactivity of the myocardium in August rats was decreased compared to that in Wistar rats. These peculiarities can determine high resistance of August rats to myocardial infarction.

Molecular screening of antibiotic-resistant determinants among ...

African Journals Online (AJOL)

Background: Globally, and particularly in developing countries, the menace of anti-microbial resistance is an accelerating problem. In Nigeria, increase in bacterial resistance has been phenotypically established but due to high cost, few molecular studies have been reported. Objectives: This study screened for presence of ...

Structure of single-chain single crystals of isotactic polystyrene and their radiation resistance

International Nuclear Information System (INIS)

Bu Haishan; Cao Jie; Xu Shengyong; Zhang Ze

1997-01-01

The structure of the single-chain single crystals of isotactic polystyrene (i-PS) was investigated by electron diffraction (ED) and high resolution electron microscopy (HREM). The nano-scale single-chain single crystals were found to be very stable to electron irradiation. According to the unit cell of i-PS crystals, the reflection rings in ED pattern and the lattice fringes in HREM images could be indexed, but the lower-index diffractions were not found. It is proposed that the single-chain single crystals are very small, thus secondary electrons may be allowed to escape and radiation damage is highly reduced, and that there are less lower-index lattice planes in the single-chain single crystals to provide sufficient diffraction intensity for recording. HREM images can be achieved at room temperature in the case of single-chain single crystals because of its stability to electron irradiation, therefore, this might be a novel experimental approach to the study of crystal structure of macromolecules

Determinants of between-country differences in ambulatory antibiotic use and antibiotic resistance in Europe: a longitudinal observational study.

Science.gov (United States)

Blommaert, A; Marais, C; Hens, N; Coenen, S; Muller, A; Goossens, H; Beutels, P

2014-02-01

To identify key determinants explaining country-year variations in antibiotic use and resistance. Ambulatory antibiotic use data [in defined daily doses per 1000 inhabitants per day (DIDs)] for 19 European countries from 1999 to 2007 were collected, along with 181 variables describing countries in terms of their agriculture, culture, demography, disease burden, education, healthcare organization and socioeconomics. After assessing data availability, overlap and relevance, multiple imputation generalized estimating equations were applied with a stepwise selection procedure to select significant determinants of global antibiotic use (expressed in DIDs), relative use of subgroups (amoxicillin and co-amoxiclav) and resistance of Escherichia coli and Streptococcus pneumoniae. Relative humidity, healthcare expenditure proportional to gross domestic product, feelings of distrust, proportion of population aged >65 years and availability of treatment guidelines were associated with higher total antibiotic use expressed in DIDs. Restrictions on marketing activities towards prescribers, population density, number of antibiotics, educational attainment and degree of atheism were associated with a lower number of total DIDs used. Relative prescribing of amoxicillin and co-amoxiclav was mainly determined by healthcare system choices [e.g. general practitioner (GP) registration and restricted marketing]. Specific antibiotic use was found to be a significant determinant of resistance for some but not all drug/organism combinations. Incentives to stimulate GP gatekeeping were associated with lower levels of resistance, and life expectancy at age 65+ and atheism were associated with more resistance. Myriad factors influence antibiotic use and resistance at the country level and an important part of these can be modified by policy choices.

Quantitative determination and monitoring of water distribution in Aespoe granite

International Nuclear Information System (INIS)

Zimmer, U.

1998-01-01

To identify possible zones of two-phase-flow and the extension of the excavation disturbed zone, geoelectric measurements are conducted in the ZEDEX- and the DEMO-tunnel. The electric resistivity of a hard rock is usually determined by its water content, its water salinity and its porosity structure. By calibration measurements of the resistivity on rocks with well known water content, a relation between resistivity and water content for Aespoe granite is determined. This relation is used to correlate the in-situ resistivity with the water content of the rock. To determine the in-situ resistivity between the ZEDEX- and the DEMO-tunnel an electrode array of nearly 300 electrodes was installed along the tunnel walls and in one borehole. With a semiautomatic recording unit which is operated by a telephone connection from the GRS-office in Braunschweig/Germany, the resistivity is monitored between and around the tunnels. To correlate the resistivity with the water content, the measured apparent resistivity has to be converted into a resistivity model of the underground. Since many thin water bearing fractures complicate this inversion process, the accuracy and resolution of the different inversion programs are checked before their application to the data. It was found that an acceptable quantitative reconstruction of the resistivity requires the integration of geometric information about the fracture zones into the inversion process. For a rough estimation of the position of possible fracture zones, a simple inversion without any geometric boundary conditions can be used. Since the maximum investigation area is limited along a single tunnel for profile measurements, tomographic measurements were also applied to estimate the resistivity distribution between the ZEDEX- and the DEMO-tunnel. These tomographic measurements have a lower resolution than the profile measurements due to the required large computer power, but result in reconstructions that give an estimate of

The resistive plate WELL detector as a single stage thick gaseous multiplier detector

Energy Technology Data Exchange (ETDEWEB)

Bressler, Shikma; Breskin, Amos; Moleri, Luca; Kumar, Ashwini; Pitt, Michael [Department of Particle Physics and Astrophysics, Weizmann Institute of Science (WIS) (Israel); Kudella, Simon [Institut fuer Experimentelle Kernphysik (IEKP), KIT (Germany)

2015-07-01

Gaseous Electron Multiplier (GEM) detector use high electric fields inside the h ole of a foil to achieve a high charge multiplication. As a thicker version of G EMs based on printed circuit board (PCB) structures, Thick Gaseous Electron Multiplier (THGEM) detectors combine the high gain of a GEM foil with the robustness, stability and low production costs of a PCB and allow a large quantity of applications that require the coverage of a large area at low cost and moderate spatial resolution. One application the Weizmann Institute of Science (WIS) develops as a member of the RD51 framework is the Resistive Plate WELL (RPWELL) detector. This single stage detector allows a very stable, discharge free operation at high gain (10{sup 5}). The single stage operation allows a low total height and make s the RPWELL a candidate for the Digital Hadronic Calorimeter (DHCAL) of the International Large Detector (ILD) at the International Linear Collider (ILC). The talk gives an insight into the way the RPWELL works and shows results from the last test beam.

Experimental research on single phase convection heat transfer in micro-fin tube

International Nuclear Information System (INIS)

Fan Guangming; Sun Zhongning; Zhu Sheng

2011-01-01

An experimental investigation of heat transfer and flow resistance characteristics of single phase water in three micro-fin tubes with different fin height was conducted. At the same time, the efficiency of micro-fin tubes within the experimental scope was evaluated and the optimal working region was determined. Based on the experimental data in the optimal working region, correlations for predicting the heat transfer and flow resistance were also given by multiple regression method. The result indicates that the micro-fin tubes can greatly enhance the single-phase heat transfer in turbulent flow, and the increase of heat transfer coefficient is higher than the increase of flow resistance. The accuracy of the correlation is very high, of which the deviation from the experimental value is very small. (authors)

Single locus complementary sex determination in Hymenoptera: an "unintelligent" design?

Directory of Open Access Journals (Sweden)

Driessen Gerard

2006-01-01

Full Text Available Abstract The haplodiploid sex determining mechanism in Hymenoptera (males are haploid, females are diploid has played an important role in the evolution of this insect order. In Hymenoptera sex is usually determined by a single locus, heterozygotes are female and hemizygotes are male. Under inbreeding, homozygous diploid and sterile males occur which form a genetic burden for a population. We review life history and genetical traits that may overcome the disadvantages of single locus complementary sex determination (sl-CSD. Behavioural adaptations to avoid matings between relatives include active dispersal from natal patches and mating preferences for non-relatives. In non-social species, temporal and spatial segregation of male and female offspring reduces the burden of sl-CSD. In social species, diploid males are produced at the expense of workers and female reproductives. In some social species, diploid males and diploid male producing queens are killed by workers. Diploid male production may have played a role in the evolution or maintenance of polygyny (multiple queens and polyandry (multiple mating. Some forms of thelytoky (parthenogenetic female production increase homozygosity and are therefore incompatible with sl-CSD. We discuss a number of hypothetical adaptations to sl-CSD which should be considered in future studies of this insect order.

Determination of resistance to salt crystallization on natural stone measured with ultrasonic wave

DEFF Research Database (Denmark)

Alm, D.; Brix, S.; Kjærgaard, H. Howe

2008-01-01

and after salt exposure. Four different stones are investigated: the limestone Bateig Azul, the sandstone Oberkirchener, the limestone Perlatino, and the limestone Travertine. The procedure for the salt crystallization test is EN 12370 standard “Natural stone test methods – Determination of resistance...

Determination of reactor parameters by single rod experiments

Energy Technology Data Exchange (ETDEWEB)

Raisic, N; Zdravkovic, Z; Ivkovic, M; Sotic, O [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

1968-10-15

The objective of this work was to determine experimentally fuel element parameters using an isolated fuel element of arbitrary construction and analyzing the accuracy of their results with the aim to apply them in analysis of reactor system. The approach is based on assumption of heterogeneous reactor theory, 'source-sink' theory. The obtained experimental results have shown the possibility of obtaining data for absorption or production properties of fuel element by analyzing the thermal and epithermal neutron density distributions around a single fuel rod placed in a sufficiently large thermal hole.

Contact-free sheet resistance determination of large area graphene layers by an open dielectric loaded microwave cavity

International Nuclear Information System (INIS)

Shaforost, O.; Wang, K.; Adabi, M.; Guo, Z.; Hanham, S.; Klein, N.; Goniszewski, S.; Gallop, J.; Hao, L.

2015-01-01

A method for contact-free determination of the sheet resistance of large-area and arbitrary shaped wafers or sheets coated with graphene and other (semi) conducting ultrathin layers is described, which is based on an open dielectric loaded microwave cavity. The sample under test is exposed to the evanescent resonant field outside the cavity. A comparison with a closed cavity configuration revealed that radiation losses have no significant influence of the experimental results. Moreover, the microwave sheet resistance results show good agreement with the dc conductivity determined by four-probe van der Pauw measurements on a set of CVD samples transferred on quartz. As an example of a practical application, correlations between the sheet resistance and deposition conditions for CVD graphene transferred on quartz wafers are described. Our method has a high potential as measurement standard for contact-free sheet resistance measurement and mapping of large area graphene samples

Impact of Nevirapine (NVP) Plasma Concentration on Selection of Resistant Virus in Mothers Who Received Single-Dose NVP To Prevent Perinatal Human Immunodeficiency Virus Type 1 Transmission and Persistence of Resistant Virus in Their Infected Children▿

OpenAIRE

Chaix, Marie-Laure; Ekouevi, Didier Koumavi; Peytavin, Gilles; Rouet, François; Tonwe-Gold, Besigin; Viho, Ida; Bequet, Laurence; Amani-Bosse, Clarisse; Menan, Hervé; Leroy, Valériane; Rouzioux, Christine; Dabis, François

2006-01-01

Nonnucleoside reverse transcriptase inhibitor resistance following the use of single-dose nevirapine (sdNVP) for the prevention of mother-to-child transmission (PMTCT) remains a concern. In the ANRS-1201/1202 Ditrame study, conducted in Abidjan, Côte d'Ivoire, a short-course regimen of zidovudine was associated with sdNVP for PMTCT. In this study, we estimate the frequency of NVP resistance and its relationship with NVP concentration in mothers. Genotypic resistance analysis was performed on ...

Superconducting transition and low-field magnetoresistance of a niobium single crystal at 4.2 deg. K

International Nuclear Information System (INIS)

Perriot, G.

1967-01-01

We report the study of the electrical resistance of a niobium single crystal, at 4.2 deg. K, from the beginning of the superconductive transition to 80 kilo oersteds. Critical fieldsH c2 and H c3 have been determined. Influences on superconductive transition of current density, field-current angle, crystal orientation and magnetoresistance have been studied. Variation laws of low-field transverse and longitudinal magneto-resistances have been determined. (author) [fr

Wear resistance of thick diamond like carbon coatings against polymeric materials used in single screw plasticizing technology

Science.gov (United States)

Zitzenbacher, G.; Liu, K.; Forsich, C.; Heim, D.

2015-05-01

Wear on the screw and barrel surface accompany polymer single screw plasticizing technology from the beginning. In general, wear on screws can be reduced by using nitrided steel surfaces, fused armour alloys on the screw flights and coatings. However, DLC-coatings (Diamond Like Carbon) comprise a number of interesting properties such as a high hardness, a low coefficient of friction and an excellent corrosion resistance due to their amorphous structure. The wear resistance of about 50 µm thick DLC-coatings against polyamide 6.6, polybutylene terephthalate and polypropylene is investigated in this paper. The tribology in the solids conveying zone of a single screw extruder until the beginning of melting is evaluated using a pin on disc tribometer and a so called screw tribometer. The polymeric pins are pressed against coated metal samples using the pin on disc tribometer and the tests are carried out at a defined normal force and sliding velocity. The screw tribometer is used to perform tribological experiments between polymer pellets and rotating coated metal shafts simulating the extruder screw. Long term experiments were performed to evaluate the wear resistance of the DLC-coating. A reduction of the coefficient of friction can be observed after a frictional distance of about 20 kilometers using glass fibre reinforced polymeric materials. This reduction is independent on the polymer and accompanied by a black layer on the wear surface of the polymeric pins. The DLC-coated metal samples show an up to 16 µm deep wear track after the 100 kilometer test period against the glass fiber filled materials only.

Mutation of environmental mycobacteria to resist silver nanoparticles also confers resistance to a common antibiotic.

Science.gov (United States)

Larimer, Curtis; Islam, Mohammad Shyful; Ojha, Anil; Nettleship, Ian

2014-08-01

Non-tuberculous mycobacteria are a threat to human health, gaining entry to the body through contaminated water systems, where they form persistent biofilms despite extensive attempts at disinfection. Silver is a natural antibacterial agent and in nanoparticle form activity is increased by a high surface area. Silver nanoparticles (AgNPs) have been used as alternative disinfectants in circulating water systems, washing machines and even clothing. However, nanoparticles, like any other antibiotic that has a pervasive durable presence, carry the risk of creating a resistant population. In this study Mycobacterium smegmatis strain mc(2)155 was cultured in AgNP enriched agar such that only a small population survived. Surviving cultures were isolated and re-exposed to AgNPs and AgNO3 and resistance to silver was compared to a negative control. After only a single exposure, mutant M. smegmatis populations were resistant to AgNPs and AgNO3. Further, the silver resistant mutants were exposed to antibiotics to determine if general resistance had been conferred. The minimum inhibitory concentration of isoniazid was four times higher for silver resistant mutants than for strain mc(2)155. However, core resistance was not conferred to other toxic metal ions. The mutants had lower resistance to CuSO4 and ZnSO4 than the mc(2)155 strain.

Environmental Sciences Electrical resistivity soundings to determine ...

African Journals Online (AJOL)

Wood, leaves, newspaper, cloth, polythene bags, plastics, glass and metal refuse interspersed with soil exhibited resistivity of 11.6 ohm-m and layer thickness of 0.7 m as obtained from the inversion of the sounding. The unsaturated layer has a resistivity of 6.8 ohm-m and thickness of 0.6 m while leachate-saturated is ...

High Frequency of a Single Nucleotide Substitution (c.-6-180T>G) of the Canine MDR1/ABCB1 Gene Associated with Phenobarbital-Resistant Idiopathic Epilepsy in Border Collie Dogs

OpenAIRE

Mizukami, Keijiro; Yabuki, Akira; Chang, Hye-Sook; Uddin, Mohammad Mejbah; Rahman, Mohammad Mahbubur; Kushida, Kazuya; Kohyama, Moeko; Yamato, Osamu

2013-01-01

A single nucleotide substitution (c.-6-180T>G) associated with resistance to phenobarbital therapy has been found in the canine MDR1/ABCB1 gene in Border Collies with idiopathic epilepsy. In the present study, a PCR-restriction fragment length polymorphism assay was developed for genotyping this mutation, and a genotyping survey was carried out in a population of 472 Border Collies in Japan to determine the current allele frequency. The survey demonstrated the frequencies of the T/T wild type...

Self-Sensing of Single Carbon Fiber/Carbon Nanotube-Epoxy Composites Using Electro-Micromechanical Techniques and Acoustic Emission

International Nuclear Information System (INIS)

Park, Joung Man; Jang, Jung Hoon; Wang, Zuo Jia; Kwon, Dong Jun; Park, Jong Kyu; Lee, Woo Il

2010-01-01

Self-sensing on micro-failure, dispersion degree and relating properties, of carbon nanotube(CNT)/epoxy composites, were investigated using wettability, electro-micromechanical technique with acoustic emission(AE). Specimens were prepared from neat epoxy as well as composites with untreated and acid-treated CNT. Degree of dispersion was evaluated comparatively by measuring volumetric electrical resistivity and its standard deviation. Apparent modulus containing the stress transfer was higher for acid-treated CNT composite than for the untreated case. Applied cyclic loading responded well for a single carbon fiber/CNT-epoxy composite by the change in contact resistivity. The interfacial shear strength between a single carbon fiber and CNT-epoxy, determined in a fiber pullout test, was lower than that between a single carbon fiber and neat epoxy. Regarding on micro-damage sensing using electrical resistivity measurement with AE, the stepwise increment in electrical resistivity was observed for a single carbon fiber/CNT-epoxy composite. On the other hand, electrical resistivity increased infinitely right after the first carbon fiber breaks for a single carbon fiber/neat epoxy composite. The occurrence of AE events of added CNT composites was much higher than the neat epoxy case, due to microfailure at the interfaces by added CNTs

Glyphosate-Resistant Parthenium hysterophorus in the Caribbean Islands: Non Target Site Resistance and Target Site Resistance in Relation to Resistance Levels.

Directory of Open Access Journals (Sweden)

Enzo Bracamonte

2016-12-01

Full Text Available Glyphosate has been the most intensely herbicide used worldwide for decades, and continues to be a single tool for controlling weeds in woody crops. However, the adoption of this herbicide in a wide range of culture systems has led to the emergence of resistant weeds. Glyphosate has been widely used primarily on citrus in the Caribbean area, but a study of resistance in the Caribbean islands of Cuba and the Dominican Republic has never been carried out. Unfortunately, Parthenium hysterophorus has developed glyphosate-resistance in both islands, independently. The resistance level and mechanisms of different P. hysterophorus accessions (three collected in Cuba (Cu-R and four collected in the Dominican Republic (Do-R have been studied under greenhouse and laboratory conditions. In in vivo assays (glyphosate dose causing 50% reduction in above-ground vegetative biomass and survival, the resistance factor levels showed susceptible accessions (Cu-S≥Do-S, low-resistance accessions (Cu-R3Do-R2>Cu-R2>Do-R3>Do-R4>Cu-R3>>Cu-S≥Do-S. Glyphosate was degraded to aminomethylphosphonic acid, glyoxylate and sarcosine by >88% in resistant accessions except in Cu-R3 and Do-R4 resistant accessions (51.12 and 44.21, respectively, whereas a little glyphosate (<9.32% was degraded in both susceptible accessions at 96 h after treatment. There were significant differences between P. hysterophorus accessions in the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS activity enzyme with and without different glyphosate rates. The R accessions showed values of between 0.026 and 0.21 µmol µg-1 TSP protein min-1 basal EPSPS activity values with respect to the S (0.024 and 0.025 accessions. The same trend was found in the EPSPS enzyme activity treated with glyphosate, where a higher enzyme activity inhibition (glyphosate µM corresponded to greater resistance levels in P. hysterophorus accessions. One amino acid substitution was found at position 106 in EPSPS, consisting

Ion beam modification of thermal stress resistance of MgO single crystals with different crystallographic faces

International Nuclear Information System (INIS)

Gurarie, V.N.; Otsuka, P.H.; Jamieson, D.N.; Williams, J.S.; Conway, M.

1999-01-01

Ion beam modification of thermal shock stress and damage resistance of MgO single crystals with various crystallographic faces is investigated. The most stable crystal faces in terms of stress and damage resistance are established. Ion implantation is shown to reduce the temperature threshold of fracture for all crystal faces tested. The (111) face is demonstrated to be of highest stability compared to (110) and (100) faces in both implanted and unimplanted crystals. At the same time ion implantation substantially increases the microcrack density for the faces tested and reduces the degree of fracture damage following thermal shock. The microcrack density is found to be highest in the crystals with (110) face in comparison with the (001) and (111) faces. The effect is analysed using fracture mechanics principles and discussed in terms of the implantation-induced lattice damage

Determining resistance to mastitis in a bovine subject involves detecting presence or absence of genetic marker associated with trait indicative of mastitis resistance of the bovine subject and/or off-spring from it

DEFF Research Database (Denmark)

2010-01-01

NOVELTY - Determining (m1) resistance to mastitis in a bovine subject, involves detecting in a sample from the bovine subject the presence or absence of at least one genetic marker that is associated with at least one trait indicative of mastitis resistance of the bovine subject and/or off......-spring from it, where the genetic marker is located on the bovine chromosome BTA11 in the region flanked by and including the zeta-chain associated protein 70kD (ZAP70) and CD8B genes, where the presence or absence of the genetic marker is indicative of mastitis resistance. USE - For determining resistance...... to mastitis in a bovine subject for determining mastitis resistance in a bovine subject; for detecting the presence or absence in a bovine subject of at least one genetic marker associated with resistance to mastitis; and for estimating breeding value in respect of susceptibility to mastitis in a bovine...

Quinolone Resistance among Salmonella enterica from Cattle, Broilers and Swine in Denmark

DEFF Research Database (Denmark)

Wiuff, C.; Baggesen, Dorte Lau; Madsen, M.

2000-01-01

This study was conducted to determine the susceptibility to nalidixic acid and fluoroquinolones of Salmonella Dublin, S. Enteritidis, and S. Typhimurium isolates from cattle, broilers, and pigs over time in Denmark and to characterise the gyrA, gyrB, and parC genes in quinolone-resistant isolates...... that quinolone-resistant isolates have emerged in recent years among food-producing animals, especially among S. Enteritidis from broilers in Denmark, and that the resistance mainly is associated with mutations in gyrA.......This study was conducted to determine the susceptibility to nalidixic acid and fluoroquinolones of Salmonella Dublin, S. Enteritidis, and S. Typhimurium isolates from cattle, broilers, and pigs over time in Denmark and to characterise the gyrA, gyrB, and parC genes in quinolone-resistant isolates...... to quinolones. A single (1.1%) S. Typhimurium isolate from 1995 and three (5.9%) from 1998 were resistant to nalidixic acid. Six (9.0%) S. Dublin isolates from 1996, four (4.2%) from 1997, and one (1.7%) from 1998 were resistant to nalidixic acid. Resistance was not observed among isolates from cattle in 1999...

Characterization of CTX-M enzymes, quinolone resistance determinants, and antimicrobial residues from hospital sewage, wastewater treatment plant, and river water.

Science.gov (United States)

Conte, Danieli; Palmeiro, Jussara Kasuko; da Silva Nogueira, Keite; de Lima, Thiago Marenda Rosa; Cardoso, Marco André; Pontarolo, Roberto; Degaut Pontes, Flávia Lada; Dalla-Costa, Libera Maria

2017-02-01

Multidrug-resistant (MDR) bacteria are widespread in hospitals and have been increasingly isolated from aquatic environments. The aim of the present study was to characterize extended-spectrum β-lactamase (ESBL) and quinolone-resistant Enterobacteriaceae from a hospital effluent, sanitary effluent, inflow sewage, aeration tank, and outflow sewage within a wastewater treatment plant (WWTP), as well as river water upstream and downstream (URW and DRW, respectively), of the point where the WWTP treated effluent was discharged. β-lactamase (bla) genes, plasmid-mediated quinolone resistance (PMQR), and quinolone resistance-determining regions (QRDRs) were assessed by amplification and sequencing in 55 ESBL-positive and/or quinolone-resistant isolates. Ciprofloxacin residue was evaluated by high performance liquid chromatography. ESBL-producing isolates were identified in both raw (n=29) and treated (n=26) water; they included Escherichia coli (32), Klebsiella pneumoniae (22) and Klebsiella oxytoca (1). Resistance to both cephalosporins and quinolone was observed in 34.4% of E. coli and 27.3% of K. pneumoniae. Resistance to carbapenems was found in 5.4% of K. pneumoniae and in K. oxytoca. Results indicate the presence of bla CTX-M (51/55, 92.7%) and bla SHV (8/55, 14.5%) ESBLs, and bla GES (2/55, 3.6%) carbapenemase-encoding resistance determinants. Genes conferring quinolone resistance were detected at all sites, except in the inflow sewage and aeration tanks. Quinolone resistance was primarily attributed to amino acid substitutions in the QRDR of GyrA (47%) or to the presence of PMQR (aac-(6')-Ib-cr, oqxAB, qnrS, and/or qnrB; 52.9%) determinants. Ciprofloxacin residue was absent only from URW. Our results have shown strains carrying ESBL genes, PMQR determinants, and mutations in the gyrA QRDR genes mainly in hospital effluent, URW, and DRW samples. Antimicrobial use, and the inefficient removal of MDR bacteria and antibiotic residue during sewage treatment, may

Detection of rifampin resistance patterns in Mycobacterium tuberculosis strains isolated in Iran by polymerase chain reaction-single-strand conformation polymorphism and direct sequencing methods

Directory of Open Access Journals (Sweden)

Bahram Nasr Isfahani

2006-09-01

Full Text Available Mutations in the rpoB locus confer conformational changes leading to defective binding of rifampin (RIF to rpoB and consequently resistance in Mycobacterium tuberculosis. Polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP was established as a rapid screening test for the detection of mutations in the rpoB gene, and direct sequencing has been unambiguously applied to characterize mutations. A total of 37 of Iranian isolates of M. tuberculosis, 16 sensitive and 21 resistant to RIF, were used in this study. A 193-bp region of the rpoB gene was amplified and PCR-SSCP patterns were determined by electrophoresis in 10% acrylamide gel and silver staining. Also, 21 samples of 193-bp rpoB amplicons with different PCR-SSCP patterns from RIFr and 10 from RIFs were sequenced. Seven distinguishable PCR-SSCP patterns were recognized in the 21 Iranian RIFr strains, while 15 out of 16 RIFs isolates demonstrated PCR-SSCP banding patterns similar to that of sensitive standard strain H37Rv. However one of the sensitive isolates demonstrated a different pattern. There were seen six different mutations in the amplified region of rpoB gene: codon 516(GAC/GTC, 523(GGG/GGT, 526(CAC/TAC, 531(TCG/TTG, 511(CTG/TTG, and 512(AGC/TCG. This study demonstrated the high specificity (93.8% and sensitivity (95.2% of PCR-SSCP method for detection of mutation in rpoB gene; 85.7% of RIFr strains showed a single mutation and 14.3% had no mutations. Three strains showed mutations caused polymorphism. Our data support the common notion that rifampin resistance genotypes are generally present mutations in codons 531 and 526, most frequently found in M. tuberculosis populations regardless of geographic origin.

Inheritance of Cry1F resistance, cross-resistance and frequency of resistant alleles in Spodoptera frugiperda (Lepidoptera: Noctuidae).

Science.gov (United States)

Vélez, A M; Spencer, T A; Alves, A P; Moellenbeck, D; Meagher, R L; Chirakkal, H; Siegfried, B D

2013-12-01

Transgenic maize, Zea maize L., expressing the Cry1F protein from Bacillus thuringiensis has been registered for Spodoptera frugiperda (J. E. Smith) control since 2003. Unexpected damage to Cry1F maize was reported in 2006 in Puerto Rico and Cry1F resistance in S. frugiperda was documented. The inheritance of Cry1F resistance was characterized in a S. frugiperda resistant strain originating from Puerto Rico, which displayed >289-fold resistance to purified Cry1F. Concentration-response bioassays of reciprocal crosses of resistant and susceptible parental populations indicated that resistance is recessive and autosomal. Bioassays of the backcross of the F1 generation crossed with the resistant parental strain suggest that a single locus is responsible for resistance. In addition, cross-resistance to Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ba, Cry2Aa and Vip3Aa was assessed in the Cry1F-resistant strain. There was no significant cross-resistance to Cry1Aa, Cry1Ba and Cry2Aa, although only limited effects were observed in the susceptible strain. Vip3Aa was highly effective against susceptible and resistant insects indicating no cross-resistance with Cry1F. In contrast, low levels of cross-resistance were observed for both Cry1Ab and Cry1Ac. Because the resistance is recessive and conferred by a single locus, an F1 screening assay was used to measure the frequency of Cry1F-resistant alleles from populations of Florida and Texas in 2010 and 2011. A total frequency of resistant alleles of 0.13 and 0.02 was found for Florida and Texas populations, respectively, indicating resistant alleles could be found in US populations, although there have been no reports of reduced efficacy of Cry1F-expressing plants.

Prevalence and determinants of fecal colonization with vancomycin-resistant Enterococcus in hospitalized patients in The Netherlands

NARCIS (Netherlands)

van den Braak, N.; Ott, A.; van Belkum, A.; Kluytmans, J. A.; Koeleman, J. G.; Spanjaard, L.; Voss, A.; Weersink, A. J.; Vandenbroucke-Grauls, C. M.; Buiting, A. G.; Verbrugh, H. A.; Endtz, H. P.

2000-01-01

To determine the prevalence and determinants of fecal carriage of vancomycin-resistant enterococci (VRE) in intensive care unit (ICU), hematology-oncology, and hemodialysis patients in The Netherlands. Descriptive, multicenter study, with yearly 1-week point-prevalence assessments between 1995 and

Crystal Structure of the Substrate-Binding Domain from Listeria monocytogenes Bile-Resistance Determinant BilE

OpenAIRE

Stephanie J. Ruiz; Gea K. Schuurman-Wolters; Bert Poolman

2016-01-01

BilE has been reported as a bile resistance determinant that plays an important role in colonization of the gastrointestinal tract by Listeria monocytogenes, the causative agent of listeriosis. The mechanism(s) by which BilE mediates bile resistance are unknown. BilE shares significant sequence similarity with ATP-binding cassette (ABC) importers that contribute to virulence and stress responses by importing quaternary ammonium compounds that act as compatible solutes. Assays using related co...

DETERMINATION OF THE SPECTRUM OF ANTIBIOTIC RESISTANCE GENES HAVE PHENOTYPIC RESISTANT STRAINS OF PARIETAL INTESTINAL MICROBIOTA IN RATS BY RT-PCR

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Bukina Y.V.

2016-06-01

Full Text Available Introduction. The problem of formation of bacterial resistance to glycopeptides and beta-lactam antibiotics (cephalosporins and carbapenems are used worldwide for the treatment of severe community acquired and nosocomial infections, especially caused by polymicrobial flora has become global and is a major factor limiting the effectiveness of antibiotic therapy. In this regard, the study of genetic microbial resistance determinants allows not only to carry out an effective antibiotic therapy, but also to identify two main processes leading to the development of epidemiologically significant events: the introduction of the agent in the risk population from the outside and in situ pathogen (spontaneous genetic drift targeted restructuring of the population. Therefore, the aim of our study was to investigate the resistance genes to carbapenems, cephalosporins, glycopeptides have clinically important phenotype of resistant strains of microorganisms families Enterobacteriaceae, Pseudomonadaceae, Bacteroidaceae, Enterococcaceae, Peptostreptococcaceae. Materials and methods. As a material for PCR studies 712 phenotypically resistant strains of microorganisms isolated from 80 rats "Wistar" line in microbiological study microflora of the wall were used. During the investigation 474 isolates of bacteria of the family Enterobacteriaceae, 39 - Pseudomonadaceae, 71 - Bacteroidaceae, 96 - Enterococcaceae, 32 - Peptostreptococcaceae were studied. Isolation of DNA from bacteria in the study was performed using reagents "DNA-Express" ("Litekh", Russia. For the detection of resistance genes by PCR in real time (RT-PCR reagent kits "FLUOROPOL-RV" ("Litekh", Russia were used. During the experiment, the VIM genes, OXA-48, NDM, KPC, responsible for the resistance of microorganisms to carbapenems, CTX-M - resistance to cephalosporins, as well as genes Van A and van B, the development of resistance to glycopeptides (vancomycin and teicoplanin were determined. Analysis

In-plane dissipation maxima and vortex-line distortions in the resistive transitions of oxygen-doped Bi2Sr2CaCu2O(8+delta) single crystals

Science.gov (United States)

Hsu, J. W. P.; Mitzi, D. B.; Kapitulnik, A.; Lee, Mark

1991-10-01

Measurements of the in-plane resistive transition of Bi2Sr2CaCu2O(8+delta) single crystals in perpendicular magnetic fields reveal that in oxygen-reduced samples a giant resistance maximum evolves with field. This is not seen in oxygenated samples with similar metallic normal resistivities. As the peak resistivity may exceed the normal resistivity, it cannot arise from ordinary vortex-motion dissipation. A model is proposed where the excess resistance results from nonrigid vortex motion coupling the out-of-plane dissipation to the in-plane resistance at temperatures where pinning effects are negligible.

Molecular mechanisms of plasmid-determined mercury and cadmium resistances in bacteria

International Nuclear Information System (INIS)

Nucifora, G.

1989-01-01

The structural basis for induction of the broad spectrum mercurial resistance operon of pDU1358 with inorganic mercury and with phenylmercury acetate was addressed by DNA sequencing analysis (that showed that a major difference occurred in the 3' 29 base pairs of the ital merR gene compared to the merR genes of Tn501 and R100) and by lac-fusion transcription experiments regulated by merR in trans. The lac-fusion results were compared with those from a narrow spectrum operon, and the pDU1358 merR deleted at the 3' end. A hybrid mer operon containing the merR gene from pDU1358 and lacking the merB gene was inducible by both phenylmercury and inorganic Hg 2+ , showing that organomercurial lyase is not needed for induction by organomercurials. A mutant form of pDU1358 merR missing the C-terminal 17 amino acids responded to inorganic Hg 2+ but not to phenylmercury, indicating that the C-terminal region of the MerR protein of the pDU1358 mer operon is required for the recognition of phenylmercury acetate. The down regulation of the mer operon by the merD gene was also measured in trans with complementing mer operons of pDU1358 or R100 or merD - mutants. In the presence of the merD gene, beta-galactosidase activity was lowered by 2 to 4 fold. The merD gene gene product was visualized by autoradiography. The Cd 2+ resistance determinant cadA of S. aureus was investigated. The nucleotide sequence of the DNA fragment containing the cadA determinant revealed two open reading frames the larger one of which is essential for expression of cadmium resistance

Systematic errors of EIT systems determined by easily-scalable resistive phantoms.

Science.gov (United States)

Hahn, G; Just, A; Dittmar, J; Hellige, G

2008-06-01

We present a simple method to determine systematic errors that will occur in the measurements by EIT systems. The approach is based on very simple scalable resistive phantoms for EIT systems using a 16 electrode adjacent drive pattern. The output voltage of the phantoms is constant for all combinations of current injection and voltage measurements and the trans-impedance of each phantom is determined by only one component. It can be chosen independently from the input and output impedance, which can be set in order to simulate measurements on the human thorax. Additional serial adapters allow investigation of the influence of the contact impedance at the electrodes on resulting errors. Since real errors depend on the dynamic properties of an EIT system, the following parameters are accessible: crosstalk, the absolute error of each driving/sensing channel and the signal to noise ratio in each channel. Measurements were performed on a Goe-MF II EIT system under four different simulated operational conditions. We found that systematic measurement errors always exceeded the error level of stochastic noise since the Goe-MF II system had been optimized for a sufficient signal to noise ratio but not for accuracy. In time difference imaging and functional EIT (f-EIT) systematic errors are reduced to a minimum by dividing the raw data by reference data. This is not the case in absolute EIT (a-EIT) where the resistivity of the examined object is determined on an absolute scale. We conclude that a reduction of systematic errors has to be one major goal in future system design.

Systematic errors of EIT systems determined by easily-scalable resistive phantoms

International Nuclear Information System (INIS)

Hahn, G; Just, A; Dittmar, J; Hellige, G

2008-01-01

We present a simple method to determine systematic errors that will occur in the measurements by EIT systems. The approach is based on very simple scalable resistive phantoms for EIT systems using a 16 electrode adjacent drive pattern. The output voltage of the phantoms is constant for all combinations of current injection and voltage measurements and the trans-impedance of each phantom is determined by only one component. It can be chosen independently from the input and output impedance, which can be set in order to simulate measurements on the human thorax. Additional serial adapters allow investigation of the influence of the contact impedance at the electrodes on resulting errors. Since real errors depend on the dynamic properties of an EIT system, the following parameters are accessible: crosstalk, the absolute error of each driving/sensing channel and the signal to noise ratio in each channel. Measurements were performed on a Goe-MF II EIT system under four different simulated operational conditions. We found that systematic measurement errors always exceeded the error level of stochastic noise since the Goe-MF II system had been optimized for a sufficient signal to noise ratio but not for accuracy. In time difference imaging and functional EIT (f-EIT) systematic errors are reduced to a minimum by dividing the raw data by reference data. This is not the case in absolute EIT (a-EIT) where the resistivity of the examined object is determined on an absolute scale. We conclude that a reduction of systematic errors has to be one major goal in future system design

Genetics and mapping of a new leaf rust resistance gene in Triticum ...

Indian Academy of Sciences (India)

AMIT KUMAR SINGH

seedling stage revealed that leaf rust resistance in Selection G12 is conditioned by a single ... closely or distantly related species of wheat (McIntosh et al. 2013 ... An effort was also made to determine the chromo- ... Materials and methods.

Towards Better Precision Medicine: PacBio Single-Molecule Long Reads Resolve the Interpretation of HIV Drug Resistant Mutation Profiles at Explicit Quasispecies (Haplotype) Level.

Science.gov (United States)

Huang, Da Wei; Raley, Castle; Jiang, Min Kang; Zheng, Xin; Liang, Dun; Rehman, M Tauseef; Highbarger, Helene C; Jiao, Xiaoli; Sherman, Brad; Ma, Liang; Chen, Xiaofeng; Skelly, Thomas; Troyer, Jennifer; Stephens, Robert; Imamichi, Tomozumi; Pau, Alice; Lempicki, Richard A; Tran, Bao; Nissley, Dwight; Lane, H Clifford; Dewar, Robin L

2016-01-01

Development of HIV-1 drug resistance mutations (HDRMs) is one of the major reasons for the clinical failure of antiretroviral therapy. Treatment success rates can be improved by applying personalized anti-HIV regimens based on a patient's HDRM profile. However, the sensitivity and specificity of the HDRM profile is limited by the methods used for detection. Sanger-based sequencing technology has traditionally been used for determining HDRM profiles at the single nucleotide variant (SNV) level, but with a sensitivity of only ≥ 20% in the HIV population of a patient. Next Generation Sequencing (NGS) technologies offer greater detection sensitivity (~ 1%) and larger scope (hundreds of samples per run). However, NGS technologies produce reads that are too short to enable the detection of the physical linkages of individual SNVs across the haplotype of each HIV strain present. In this article, we demonstrate that the single-molecule long reads generated using the Third Generation Sequencer (TGS), PacBio RS II, along with the appropriate bioinformatics analysis method, can resolve the HDRM profile at a more advanced quasispecies level. The case studies on patients' HIV samples showed that the quasispecies view produced using the PacBio method offered greater detection sensitivity and was more comprehensive for understanding HDRM situations, which is complement to both Sanger and NGS technologies. In conclusion, the PacBio method, providing a promising new quasispecies level of HDRM profiling, may effect an important change in the field of HIV drug resistance research.

Outcomes with single agent LIPO-DOX in platinum-resistant ovarian and fallopian tube cancers and primary peritoneal adenocarcinoma - Chiang Mai University Hospital experience.

Science.gov (United States)

Suprasert, Prapaporn; Manopunya, Manatsawee; Cheewakriangkrai, Chalong

2014-01-01

Single pegylated liposomal doxorubicin (PLD) is commonly used as a salvage treatment in platinum-resistant ovarian cancer, fallopian tube cancer and primary peritoneal adenocarcinoma (PPA) with a satisfactory outcome. However, the data for second generation PLD administered in this setting are still limited. We conducted a retrospective study to evaluate the outcome of patients who received single-agent second generation PLD (LIPO-DOX) after the development of clinical platinum resistance. The study period was between March 2008 and March 2013. LIPO-DOX was administered intravenously 40 mg/m2 every 28 days until disease progression, but for not more than six cycles. The response rate was evaluated using the Gynecologic Cancer Intergroup (GCIG) criteria while the toxicity was evaluated according to WHO criteria. Twenty-nine patients met the inclusion criteria in the study period with an overall response rate of 13.8%. The median progression free survival and overall survival were three and eleven months, respectively. With the total of 96 cycles of chemotherapy, the patients developed grades 3 and 4 hematologic toxicity as follows: anemia, 0%, leukopenia, 9.6%, neutropenia, 32.3% and thrombocytopenia, 0%. In conclusion, the single agent second generation PLD demonstrated modest efficacy in patients with platinum-resistant ovarian cancer, fallopian tube cancer and PPA without serious toxicity.

Identification and Determination of Drug Resistant of Candida species isolated from Hospital Acquired Infections

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Kambiz Diba

2015-01-01

Full Text Available Background & aim: Currently, the use of antifungal azole group and yeasts resistant to these drugs is increasing. The aim of this study was to isolate and identify the yeasts obtained from candidiasis patients and furthermore determining thier antifungal resistance. Methods: In the present descriptive study, infections samples were collected from 256 patients with suspected nosocomial candidiasis, then direct exam and culture were performed. Yeast colonies were identified using phenotypic methods, polymerase chain reaction method and enzyme digestion. Data were analyzed using Descriptive statistical tests. Results: Of sixty isolated yeast, thirty-seven cases of Candida albicans (61.6%, seven cases of C. krusei and C. glabrata (11.6% each, five cases of C. dubliniensis (8.3% and four cases of C. tropicalis (6.6% were indicated. The study showed that the sensitivity of C. albicans and C. cruise species to amphotericin B was negligible in disk diffusion and very sensitve in microdilution. Conclusion: Inspite of the results of antifungal susceptibility test of strains studied did not show high resistance, but screening for drug-resistant Candida isolates in Candida infection by disk diffusion and microdilution methods for new cases of drug resistance is reasonable.

An Experimental Study on Slurry Erosion Resistance of Single and Multilayered Deposits of Ni-WC Produced by Laser-Based Powder Deposition Process

Science.gov (United States)

Balu, Prabu; Hamid, Syed; Kovacevic, Radovan

2013-11-01

Single and multilayered deposits containing different mass fractions of tungsten carbide (WC) in nickel (Ni)-matrix (NT-20, NT-60, NT-80) are deposited on a AISI 4140 steel substrate using a laser-based powder deposition process. The transverse cross section of the coupons reveals that the higher the mass fraction of WC in Ni-matrix leads to a more uniform distribution through Ni-matrix. The slurry erosion resistance of the fabricated coupons is tested at three different impingement angles using an abrasive water jet cutting machine, which is quantified based on the erosion rate. The top layer of a multilayered deposit (i.e., NT-60 in a two-layer NT-60 over NT-20 deposit) exhibits better erosion resistance at all three tested impingement angles when compared to a single-layer (NT-60) deposit. A definite increase in the erosion resistance is noted with an addition of nano-size WC particles. The relationship between the different mass fractions of reinforcement (WC) in the deposited composite material (Ni-WC) and their corresponding matrix (Ni) hardness on the erosion rate is studied. The eroded surface is analyzed in the light of a three-dimensional (3-D) profilometer and a scanning electron microscope (SEM). The results show that a volume fraction of approximately 62% of WC with a Ni-matrix hardness of 540 HV resulting in the gouging out of WC from the Ni-matrix by the action of slurry. It is concluded that the slurry erosion resistance of the AISI 4140 steel can be significantly enhanced by introducing single and multilayered deposits of Ni-WC composite material fabricated by the laser-based powder deposition process.

Efficiency determination of resistive plate chambers for fast quasi-monoenergetic neutrons

Energy Technology Data Exchange (ETDEWEB)

Roeder, M.; Cowan, T.E.; Kempe, M.; Yakorev, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universitaet Dresden, Dresden (Germany); Elekes, Z. [MTA ATOMKI, Debrecen (Hungary); Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Aumann, T.; Caesar, C. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Technische Universitaet Darmstadt, Darmstadt (Germany); Bemmerer, D.; Sobiella, M.; Stach, D.; Wagner, A. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Boretzky, K.; Hehner, J.; Heil, M. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Maroussov, V. [Universitaet zu Koeln, Koeln (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Nusair, O. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Al-Balqa Applied University, Salt (Jordan); Prokofiev, A.V. [Uppsala University, The Svedberg Laboratory, Uppsala (Sweden); Reifarth, R. [Johann Wolfgang Goethe - Universitaet, Frankfurt am Main (Germany); Zilges, A. [Universitaet zu Koeln, Koeln (Germany); Zuber, K. [Technische Universitaet Dresden, Dresden (Germany); Collaboration: R3B Collaboration

2014-07-15

Composite detectors made of stainless-steel converters and multigap resistive plate chambers have been irradiated with quasi-monoenergetic neutrons with a peak energy of 175 MeV. The neutron detection efficiency has been determined using two different methods. The data are in agreement with the output of Monte Carlo simulations. The simulations are then extended to study the response of a hypothetical array made of these detectors to energetic neutrons from a radioactive ion beam experiment. (orig.)

Determination of rust resistance genes in pakistani bread wheats

International Nuclear Information System (INIS)

Qamar, M.; Ahmad, S.D.; Rabbani, M.A.; Shinwari, Z.K.

2014-01-01

Stripe and leaf rusts are the major constraints to bread wheat production in Pakistan. Molecular markers were used to investigate the presence of leaf rust and stripe rust resistance gene cluster Lr34/Yr18 and stem rust resistance gene Sr2 in 52 Pakistani bread wheat cultivars/lines. PCR amplification of DNA fragments using DNA marker csLV-34 showed that 13 of the studied cultivars/lines, namely 03FJ26, NR 337, NR 339, NR 347, NR 350, Manthar, Margalla 99, Iqbal 2000, Saleem 2000, Wafaq 2001, Marwat 2001, Pirsabak 2004 and Fareed 2006 carry leaf rust and stripe rust resistance genes Lr34/Yr18. Stem rust resistance gene Sr2 was observed in 36 Pakistani spring wheat cultivars/lines using stm560.3tgag marker. The slow rusting gene Sr2 needs to be combined with additional stem rust resistance genes to establish durable resistance against Ug99 in modern wheat cultivars. Low frequency of Lr34/Yr18 was found in Pakistani wheats. This gene cluster needs to be incorporated into Pakistani wheats for durable rust resistance. (author)

Error compensation of single-antenna attitude determination using GNSS for Low-dynamic applications

Science.gov (United States)

Chen, Wen; Yu, Chao; Cai, Miaomiao

2017-04-01

GNSS-based single-antenna pseudo-attitude determination method has attracted more and more attention from the field of high-dynamic navigation due to its low cost, low system complexity, and no temporal accumulated errors. Related researches indicate that this method can be an important complement or even an alternative to the traditional sensors for general accuracy requirement (such as small UAV navigation). The application of single-antenna attitude determining method to low-dynamic carrier has just started. Different from the traditional multi-antenna attitude measurement technique, the pseudo-attitude attitude determination method calculates the rotation angle of the carrier trajectory relative to the earth. Thus it inevitably contains some deviations comparing with the real attitude angle. In low-dynamic application, these deviations are particularly noticeable, which may not be ignored. The causes of the deviations can be roughly classified into three categories, including the measurement error, the offset error, and the lateral error. Empirical correction strategies for the formal two errors have been promoted in previous study, but lack of theoretical support. In this paper, we will provide quantitative description of the three type of errors and discuss the related error compensation methods. Vehicle and shipborne experiments were carried out to verify the feasibility of the proposed correction methods. Keywords: Error compensation; Single-antenna; GNSS; Attitude determination; Low-dynamic

Validation of the method for determination of the thermal resistance of fouling in shell and tube heat exchangers

International Nuclear Information System (INIS)

Markowski, Mariusz; Trafczynski, Marian; Urbaniec, Krzysztof

2013-01-01

Highlights: • Heat recovery in a heat exchanger network (HEN). • A novel method for on-line determination of the thermal resistance of fouling is presented. • Details are developed for shell and tube heat exchangers. • The method was validated and sensibility analysis was carried out. • Developed approach allows long-term monitoring of changes in the HEN efficiency. - Abstract: A novel method for on-line determination of the thermal resistance of fouling in shell and tube heat exchangers is presented. It can be applied under the condition that the data on pressure, temperature, mass flowrate and thermophysical properties of both heat-exchanging media are continuously available. The calculation algorithm for use in the novel method is robust and ensures reliable determination of the thermal resistance of fouling even if the operating parameters fluctuate. The method was validated using measurement data retrieved from the operation records of a heat exchanger network connected with a crude distillation unit rated 800 t/h. Sensibility analysis of the method was carried out and the calculated values of the thermal resistance of fouling were critically reviewed considering the results of qualitative evaluation of fouling layers in the exchangers inspected during plant overhaul

Origin and spectroscopic determination of trigonal anisotropy in a heteronuclear single-molecule magnet

Science.gov (United States)

Sorace, L.; Boulon, M.-E.; Totaro, P.; Cornia, A.; Fernandes-Soares, J.; Sessoli, R.

2013-09-01

W-band (ν ≅ 94 GHz) electron paramagnetic resonance (EPR) spectroscopy was used for a single-crystal study of a star-shaped Fe3Cr single-molecule magnet (SMM) with crystallographically imposed trigonal symmetry. The high resolution and sensitivity accessible with W-band EPR allowed us to determine accurately the axial zero-field splitting terms for the ground (S = 6) and first two excited states (S = 5 and S = 4). Furthermore, spectra recorded by applying the magnetic field perpendicular to the trigonal axis showed a π/6 angular modulation. This behavior is a signature of the presence of trigonal transverse magnetic anisotropy terms whose values had not been spectroscopically determined in any SMM prior to this work. Such in-plane anisotropy could only be justified by dropping the so-called “giant spin approach” and by considering a complete multispin approach. From a detailed analysis of experimental data with the two models, it emerged that the observed trigonal anisotropy directly reflects the structural features of the cluster, i.e., the relative orientation of single-ion anisotropy tensors and the angular modulation of single-ion anisotropy components in the hard plane of the cluster. Finally, since high-order transverse anisotropy is pivotal in determining the spin dynamics in the quantum tunneling regime, we have compared the angular dependence of the tunnel splitting predicted by the two models upon application of a transverse field (Berry-phase interference).

Effects of junction resistance and counterelectrode material on point-contact tunneling into single- and polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7-y/

Energy Technology Data Exchange (ETDEWEB)

Moog, E.R.; Hawley, M.E.; Gray, K.E.; Liu, J.Z.; Hinks, D.G.; Capone, D.W. II; Downey, J.

1988-06-01

The effects of junction resistance and counterelectrode material on the results of point-contact tunneling studies into single- and polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7-y/ are illustrated. Although reasonably symmetric I(V) curves predominantly indicate energy gap values /Delta/ /approx/ 20 meV, large asymmetries are often found for high-resistance junctions. Very low-resistance junctions show the expected behavior of pure metallic bridge and indicate /Delta/ /approx/ 25-30 meV.

Negligible risk of inducing resistance in Mycobacterium tuberculosis with single-dose rifampicin as post-exposure prophylaxis for leprosy.

Science.gov (United States)

Mieras, Liesbeth; Anthony, Richard; van Brakel, Wim; Bratschi, Martin W; van den Broek, Jacques; Cambau, Emmanuelle; Cavaliero, Arielle; Kasang, Christa; Perera, Geethal; Reichman, Lee; Richardus, Jan Hendrik; Saunderson, Paul; Steinmann, Peter; Yew, Wing Wai

2016-06-08

Post-exposure prophylaxis (PEP) for leprosy is administered as one single dose of rifampicin (SDR) to the contacts of newly diagnosed leprosy patients. SDR reduces the risk of developing leprosy among contacts by around 60 % in the first 2-3 years after receiving SDR. In countries where SDR is currently being implemented under routine programme conditions in defined areas, questions were raised by health authorities and professional bodies about the possible risk of inducing rifampicin resistance among the M. tuberculosis strains circulating in these areas. This issue has not been addressed in scientific literature to date. To produce an authoritative consensus statement about the risk that SDR would induce rifampicin-resistant tuberculosis, a meeting was convened with tuberculosis (TB) and leprosy experts. The experts carefully reviewed and discussed the available evidence regarding the mechanisms and risk factors for the development of (multi) drug-resistance in M. tuberculosis with a view to the special situation of the use of SDR as PEP for leprosy. They concluded that SDR given to contacts of leprosy patients, in the absence of symptoms of active TB, poses a negligible risk of generating resistance in M. tuberculosis in individuals and at the population level. Thus, the benefits of SDR prophylaxis in reducing the risk of developing leprosy in contacts of new leprosy patients far outweigh the risks of generating drug resistance in M. tuberculosis.

Determination of antibiotic resistance profile in Klebsiella pneumonia strains isolated from urinary tract infections of patients hospitalized in Peyambaran hospital (Tehran-Iran

Directory of Open Access Journals (Sweden)

Marzieh Tavakol

2017-04-01

Full Text Available Background: Urinary tract infection (UTI is the second prevalent infection in human mostly caused by Escherichia coli and Klebsiella pneumonia. The aim of this study was to determine the antibiotic resistance profile and detect the prevalence of antibiotic resistance encoding genes in K .pneumoniae isolated from UTI. Materials and Methods: Fifty K. pneumonia strains isolated from 122 UTI samples of hospitalized patients in Payambaran Hospital (Tehran, Iran which were subjected to this study (2014 were confirmed by standard biochemical tests. Isolates were tested for susceptibility to 10 antimicrobial drugs by using disk diffusion method. Antibiotic resistance encoding genes frequently include the aadA1, aac(3-IV, sul1, blaSHV, Cat1, cmlA, tetA, tetB, dfrA1, CITM, qnr in isolates were determined by PCR. Results: The highest antibiotic resistance in K. pneumoniae isolates were for Tetracycline and the lowest resistance (2% for Gentamicin and Imipenem. To determine the frequency of antibiotic resistant genes, 64% and 4% of isolates had tetA and Gentamicin-(aac(3-IV resistant genes, respectively. Conclusion: Frequency of antibiotic resistance encoding genes may have important and basic role in the occurrence and transfer of antibiotic resistance which can be due to the indiscriminate use of antibiotics.

FRC collisionless resistivity

International Nuclear Information System (INIS)

Tajima, T.; Horton, W.

1990-01-01

Ions in the field reversed configuration (FRC) exhibit stochastic orbits due to the field null and the curvature of poloidal field lines. Velocity correlations of these particles decay in a power law fashion t -m where 1 ≤ m ≤ 2. This decay of the single particle correlation function is characteristic of the long tail correlations of strongly chaotic or nonlinear systems found in other problems of statistical physics. This decay of correlations gives rise to a collisionless resistivity that can far exceed the collisional resistivity in an FRC plasma. The finite correlation τ c of a single particle limits the acceleration in the electric field producing the finite resistivity. Maxwellian test particle distributions are integrated to find the measure of the set of stochastic ions that contribute to the collisionless resistivity. The computed conductivity is proportional to the square root of the characteristic ion gyroradius in both simulation and theory

Experimental determination of fuel-cladding thermal contact resistance

International Nuclear Information System (INIS)

Maglic, K.; Zivotic, Z.

1968-01-01

Thermal resistance of the UO 2 fuel - Zr-2 cladding was measure by the same experimental apparatus which was used for measuring the thermal conductivity of ceramic fuel. Thermal resistance was measure for a series of heat flux values and the dependence of thermal resistance on the flux is given within in the range from 0.66 W/cm 2 to 13.3 W/cm 2 . The temperature drop on the contact surface was between 39 deg C and 181.7 deg C, proportional to the increase of the heat flux [sr

A single amino acid substitution in the core protein of West Nile virus increases resistance to acidotropic compounds.

Directory of Open Access Journals (Sweden)

Miguel A Martín-Acebes

Full Text Available West Nile virus (WNV is a worldwide distributed mosquito-borne flavivirus that naturally cycles between birds and mosquitoes, although it can infect multiple vertebrate hosts including horses and humans. This virus is responsible for recurrent epidemics of febrile illness and encephalitis, and has recently become a global concern. WNV requires to transit through intracellular acidic compartments at two different steps to complete its infectious cycle. These include fusion between the viral envelope and the membrane of endosomes during viral entry, and virus maturation in the trans-Golgi network. In this study, we followed a genetic approach to study the connections between viral components and acidic pH. A WNV mutant with increased resistance to the acidotropic compound NH4Cl, which blocks organelle acidification and inhibits WNV infection, was selected. Nucleotide sequencing revealed that this mutant displayed a single amino acid substitution (Lys 3 to Glu on the highly basic internal capsid or core (C protein. The functional role of this replacement was confirmed by its introduction into a WNV infectious clone. This single amino acid substitution also increased resistance to other acidification inhibitor (concanamycin A and induced a reduction of the neurovirulence in mice. Interestingly, a naturally occurring accompanying mutation found on prM protein abolished the resistant phenotype, supporting the idea of a genetic crosstalk between the internal C protein and the external glycoproteins of the virion. The findings here reported unveil a non-previously assessed connection between the C viral protein and the acidic pH necessary for entry and proper exit of flaviviruses.

A single amino acid substitution in the core protein of West Nile virus increases resistance to acidotropic compounds.

Science.gov (United States)

Martín-Acebes, Miguel A; Blázquez, Ana-Belén; de Oya, Nereida Jiménez; Escribano-Romero, Estela; Shi, Pei-Yong; Saiz, Juan-Carlos

2013-01-01

West Nile virus (WNV) is a worldwide distributed mosquito-borne flavivirus that naturally cycles between birds and mosquitoes, although it can infect multiple vertebrate hosts including horses and humans. This virus is responsible for recurrent epidemics of febrile illness and encephalitis, and has recently become a global concern. WNV requires to transit through intracellular acidic compartments at two different steps to complete its infectious cycle. These include fusion between the viral envelope and the membrane of endosomes during viral entry, and virus maturation in the trans-Golgi network. In this study, we followed a genetic approach to study the connections between viral components and acidic pH. A WNV mutant with increased resistance to the acidotropic compound NH4Cl, which blocks organelle acidification and inhibits WNV infection, was selected. Nucleotide sequencing revealed that this mutant displayed a single amino acid substitution (Lys 3 to Glu) on the highly basic internal capsid or core (C) protein. The functional role of this replacement was confirmed by its introduction into a WNV infectious clone. This single amino acid substitution also increased resistance to other acidification inhibitor (concanamycin A) and induced a reduction of the neurovirulence in mice. Interestingly, a naturally occurring accompanying mutation found on prM protein abolished the resistant phenotype, supporting the idea of a genetic crosstalk between the internal C protein and the external glycoproteins of the virion. The findings here reported unveil a non-previously assessed connection between the C viral protein and the acidic pH necessary for entry and proper exit of flaviviruses.

The rarely reported tet(31) tetracycline resistance determinant is common in Gallibacterium anatis

DEFF Research Database (Denmark)

Bojesen, Anders M.; Bager, Ragnhild J.; Ifrah, Dan

2011-01-01

The present investigation was undertaken to identify and characterize the tetracycline resistance determinant in 22 Gallibacterium anatis strains for which no determinant was identified using primers specific for tet(A, B, C, D, E, G, H, K, L, M, O). A recent study found tet(B) to be the most pre...... from very different production systems and localities. In addition, tet(31) was identified in strains isolated over a 30-year period. This is the first report on tet(31) since its original identification in Aeromonas salmonicida....

Children with Steroid-resistant Nephrotic Syndrome: a Single-Center Study

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Rahime Renda

2016-01-01

Full Text Available Background and Aim: Steroid-resistant nephrotic syndrome (SRNS accounts for 10%-20% of all cases of idiopathic nephrotic syndrome. These patients are at risk of developing end-stage renal disease. The aim of this study was to determine the demographic characteristics, renal biopsy findings, response to immunosuppressive treatment, and prognosis in pediatric patients with SRNS.Materials and Methods: This retrospective study included 31 patients diagnosed as primary SRNS. Age at first episode, gender, parental consanguinity, and familial history of nephrotic syndrome were recorded. Demographic characteristics, renal biopsy findings, response to immunosuppressive treatment, and prognosis were analyzed, as were the number of and treatment of relapses, extra-renal manifestations, and complications of disease and treatment.Results: Mean age at first episode of nephrotic syndrome was 4,1±2,9 years. At the end of the first immunosuppressive treatment cycle, 14 (51.8% patients achieved complete remission, 4 (14.8% patients achieved partial remission, and 9 patients (33.3% did not achieve remission. Analysis of the final status of the patients showed that 16 patients (51.6% developed remission, 5 patients (16% continued to have nephrotic range proteinuria and 10 patients (32% developed chronic renal failure (CRF.Conclusion: The treatment of SRNS remains controversial. Early genetic testing can help the inevitable immunosuppressive treatments which may not be effective and have several side effects. Calcineurin inhibitors and mycophenolate mofetil are known to be effective immunosuppressive drugs for treating steroid resistant nephrotic syndrome .

Resistance and cross-resistance profile of the diaryltriazine NNRTI and candidate microbicide UAMC01398.

Science.gov (United States)

Ariën, Kevin K; Venkatraj, Muthusamy; Michiels, Johan; Joossens, Jurgen; Vereecken, Katleen; Van der Veken, Pieter; Heeres, Jan; De Winter, Hans; Heyndrickx, Leo; Augustyns, Koen; Vanham, Guido

2016-05-01

The resistance development, cross-resistance to other NNRTIs and the impact of resistance on viral replicative fitness were studied for the new and potent NNRTI UAMC01398. Resistance was selected by dose escalation and by single high-dose selection against a comprehensive panel of NNRTIs used as therapeutics and NNRTIs under investigation for pre-exposure prophylaxis of sexual HIV transmission. A panel of 27 site-directed mutants with single mutations or combinations of mutations involved in reverse transcriptase (RT) inhibitor-mediated resistance was developed and used to confirm resistance to UAMC01398. Cross-resistance to other NNRTIs was assessed, as well as susceptibility of UAMC01398-resistant HIV to diarylpyrimidine-resistant viruses. Finally, the impact of UAMC01398 resistance on HIV replicative fitness was studied. We showed that UAMC01398 has potent activity against dapivirine-resistant HIV, that at least four mutations in the RT are required in concert for resistance and that the resistance profile is similar to rilpivirine, both genotypically and phenotypically. Resistance development to UAMC01398 is associated with a severe fitness cost. These data, together with the enhanced safety profile and good solubility in aqueous gels, make UAMC01398 an excellent candidate for HIV topical prevention. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Satellite single-axis attitude determination based on Automatic Dependent Surveillance - Broadcast signals

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Zhou, Kaixing; Sun, Xiucong; Huang, Hai; Wang, Xinsheng; Ren, Guangwei

2017-10-01

The space-based Automatic Dependent Surveillance - Broadcast (ADS-B) is a new technology for air traffic management. The satellite equipped with spaceborne ADS-B system receives the broadcast signals from aircraft and transfers the message to ground stations, so as to extend the coverage area of terrestrial-based ADS-B. In this work, a novel satellite single-axis attitude determination solution based on the ADS-B receiving system is proposed. This solution utilizes the signal-to-noise ratio (SNR) measurement of the broadcast signals from aircraft to determine the boresight orientation of the ADS-B receiving antenna fixed on the satellite. The basic principle of this solution is described. The feasibility study of this new attitude determination solution is implemented, including the link budget and the access analysis. On this basis, the nonlinear least squares estimation based on the Levenberg-Marquardt method is applied to estimate the single-axis orientation. A full digital simulation has been carried out to verify the effectiveness and performance of this solution. Finally, the corresponding results are processed and presented minutely.

Absolute determination of single-stranded and self-complementary adeno-associated viral vector genome titers by droplet digital PCR.

Science.gov (United States)

Lock, Martin; Alvira, Mauricio R; Chen, Shu-Jen; Wilson, James M

2014-04-01

Accurate titration of adeno-associated viral (AAV) vector genome copies is critical for ensuring correct and reproducible dosing in both preclinical and clinical settings. Quantitative PCR (qPCR) is the current method of choice for titrating AAV genomes because of the simplicity, accuracy, and robustness of the assay. However, issues with qPCR-based determination of self-complementary AAV vector genome titers, due to primer-probe exclusion through genome self-annealing or through packaging of prematurely terminated defective interfering (DI) genomes, have been reported. Alternative qPCR, gel-based, or Southern blotting titering methods have been designed to overcome these issues but may represent a backward step from standard qPCR methods in terms of simplicity, robustness, and precision. Droplet digital PCR (ddPCR) is a new PCR technique that directly quantifies DNA copies with an unparalleled degree of precision and without the need for a standard curve or for a high degree of amplification efficiency; all properties that lend themselves to the accurate quantification of both single-stranded and self-complementary AAV genomes. Here we compare a ddPCR-based AAV genome titer assay with a standard and an optimized qPCR assay for the titration of both single-stranded and self-complementary AAV genomes. We demonstrate absolute quantification of single-stranded AAV vector genomes by ddPCR with up to 4-fold increases in titer over a standard qPCR titration but with equivalent readout to an optimized qPCR assay. In the case of self-complementary vectors, ddPCR titers were on average 5-, 1.9-, and 2.3-fold higher than those determined by standard qPCR, optimized qPCR, and agarose gel assays, respectively. Droplet digital PCR-based genome titering was superior to qPCR in terms of both intra- and interassay precision and is more resistant to PCR inhibitors, a desirable feature for in-process monitoring of early-stage vector production and for vector genome biodistribution

Linezolid-resistant enterococci in Polish hospitals: species, clonality and determinants of linezolid resistance.

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Gawryszewska, I; Żabicka, D; Hryniewicz, W; Sadowy, E

2017-07-01

The significant increase of the linezolid-resistant enterococci (LRE) has been observed in Polish hospitals since 2012 and our study aimed at elucidating the possible reasons for this phenomenon. Polish LRE isolates were analysed by multilocus-sequence typing (MLST) and multiple locus variable-number tandem repeat (VNTR) analysis (MLVA), polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (PCR-RFLP) to establish clonal relatedness and mechanism of linezolid resistance, respectively. Fifty analysed LRE (2008-2015) included mostly Enterococcus faecium (82%) and Enterococcus faecalis (16%). Enterococcus faecium belonged to the hospital-adapted lineages 17/18 and 78, while E. faecalis isolates represented ST6, a hospital-associated type, and ST116, found in both humans and food-production animals. The G2576T 23S rRNA mutation was the most frequent (94%) mechanism of linezolid/tedizolid resistance of LRE. None of the isolates carried the plasmid-associated gene of Cfr methyltransferase, whereas optrA, encoding the ABC-type drug transporter, was identified in two E. faecalis isolates. In these isolates, optrA was located on a plasmid, transferable to both E. faecium and E. faecalis, whose partial (36.3 kb) sequence was 100% identical to the pE394 plasmid, identified previously in China in both clinical and farm animal isolates. The optrA-E. faecium transconjugant displayed a significant growth deficiency, in contrast to the optrA-E. faecalis. Our study indicates the role of mutation acquisition by hospital-adapted clones of enterococci as a major driver of increasing resistance to linezolid and tedizolid. Transferability and apparent lack of a biological cost of resistance suggest that E. faecalis may be a natural reservoir of optrA, an emerging mechanism of oxazolidinone resistance.

Critical current, pinning and resistive state of superconducting single-crystal niobium with different types of defect structure

International Nuclear Information System (INIS)

Sokolenko, V.I.; Starodubov, Ya.D.

2005-01-01

Critical current pinning and resistive state of single crystal niobium of texture orientation are studied for different structural states obtained by rolling at 20 K by 42% and polishing the surface layers. It is found that the heterogeneous structures typical of the strained sample even after its thinning down to approx 10% display a lower current-carrying capability due to an increase of the thermomagnetic instability within the fragmented structure sections in the near-surface layers. For a homogeneous defect structure of the sample core with the density of equilibrium distributed dislocations of 1.3 centre dot 10 11 cm -2 , a correlation between the normal current density and the critical current density in the resistive state is found, in agreement with the concepts of flux creep due to the scatter of local values of J c

Detection of HIV drug resistance mutations in pregnant women receiving single dose Nevirapine in south India

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Mini S Jacob

2011-01-01

Full Text Available Background: Single dose of Nevirapine to prevent mother to child transmission of HIV is the commonest preventive regimen in resource-limited countries. Objectives: The objective of this study was to detect drug-resistant virus after single dose of Nevirapine (sdNVP provided to delivering HIV seropositive (HIV+ve women and to evaluate the time taken for its decay. Results: Of the 36 consenting HIV+ve pregnant women enrolled into the study, the mean hemoglobin and total lymphocyte counts were 10.8 g/dl and 1843 cells/mm 3 , respectively. Mean CD4 counts in 64% of women was 363 cells/mm 3 and mean viral load for 16/36 women was 28,143 copies/ml of plasma. Nevirapine-resistance mutations were detected in 28% of women at delivery; using OLA (Oligonucleotide Ligation Assay. K103N mutations were seen in 19.4% of women while the Y181C mutation was seen in 5%. Both the mutations were detected in 2.7% of women. Sequential blood samples collected at delivery, 7-10 days, 6 weeks, 4 months, 6 months and one year postpartum showed that 81% of K103N mutations and 66.7% of Y181C mutations were detected at 6 weeks postpartum . Wild-type virus had replaced the mutants by one year postpartum in all women except one. Conclusion : These observations are relevant for future treatment with antiretroviral therapy in these women for their HIV disease.

Drug Resistance and Pseudoresistance: An Unintended Consequence of Enteric Coating Aspirin

Science.gov (United States)

Grosser, Tilo; Fries, Susanne; Lawson, John A.; Kapoor, Shiv C.; Grant, Gregory R.; FitzGerald, Garret A.

2013-01-01

Background Low dose aspirin reduces the secondary incidence of myocardial infarction and stroke. Drug resistance to aspirin might result in treatment failure. Despite this concern, no clear definition of “aspirin resistance” has emerged and estimates of its incidence have varied remarkably. We aimed to determine the commonality of a mechanistically consistent, stable and specific phenotype of true pharmacological resistance to aspirin – such as might be explained by genetic causes. Methods and Results Healthy volunteers (n=400) were screened for their response to a single oral dose of 325 mg immediate release or enteric coated aspirin. Response parameters reflected the activity of aspirin's molecular target, cyclooxygenase-1. Individuals who appeared “aspirin resistant” on one occasion underwent repeat testing and if still “resistant” were exposed to low dose enteric coated aspirin (81 mg) and clopidogrel (75 mg) for one week each. Variable absorption caused a high frequency of apparent resistance to a single dose of 325 mg enteric coated aspirin (up to 49%) but not to immediate release aspirin (0%). All individuals responded to aspirin upon repeated exposure, extension of the post dosing interval or addition of aspirin to their platelets ex vivo. Conclusions Pharmacological resistance to aspirin is rare; this study failed to identify a single case of true drug resistance. Pseudoresistance, reflecting delayed and reduced drug absorption, complicates enteric coated but not immediate release aspirin administration. Clinical Trial Registration Information clinicaltrials.gov. Identifier: NCT00948987. PMID:23212718

Spatial distribution of single-nucleotide polymorphisms related to fungicide resistance and implications for sampling.

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Van der Heyden, H; Dutilleul, P; Brodeur, L; Carisse, O

2014-06-01

Spatial distribution of single-nucleotide polymorphisms (SNPs) related to fungicide resistance was studied for Botrytis cinerea populations in vineyards and for B. squamosa populations in onion fields. Heterogeneity in this distribution was characterized by performing geostatistical analyses based on semivariograms and through the fitting of discrete probability distributions. Two SNPs known to be responsible for boscalid resistance (H272R and H272Y), both located on the B subunit of the succinate dehydrogenase gene, and one SNP known to be responsible for dicarboximide resistance (I365S) were chosen for B. cinerea in grape. For B. squamosa in onion, one SNP responsible for dicarboximide resistance (I365S homologous) was chosen. One onion field was sampled in 2009 and another one was sampled in 2010 for B. squamosa, and two vineyards were sampled in 2011 for B. cinerea, for a total of four sampled sites. Cluster sampling was carried on a 10-by-10 grid, each of the 100 nodes being the center of a 10-by-10-m quadrat. In each quadrat, 10 samples were collected and analyzed by restriction fragment length polymorphism polymerase chain reaction (PCR) or allele specific PCR. Mean SNP incidence varied from 16 to 68%, with an overall mean incidence of 43%. In the geostatistical analyses, omnidirectional variograms showed spatial autocorrelation characterized by ranges of 21 to 1 m. Various levels of anisotropy were detected, however, with variograms computed in four directions (at 0°, 45°, 90°, and 135° from the within-row direction used as reference), indicating that spatial autocorrelation was prevalent or characterized by a longer range in one direction. For all eight data sets, the β-binomial distribution was found to fit the data better than the binomial distribution. This indicates local aggregation of fungicide resistance among sampling units, as supported by estimates of the parameter θ of the β-binomial distribution of 0.09 to 0.23 (overall median value = 0

State Waste Discharge Permit Application: Electric resistance tomography testing

Energy Technology Data Exchange (ETDEWEB)

1994-04-01

This permit application documentation is for a State Waste Discharge Permit issued in accordance with requirements of Washington Administrative Code 173-216. The activity being permitted is a technology test using electrical resistance tomography. The electrical resistance tomography technology was developed at Lawrence Livermore National Laboratory and has been used at other waste sites to track underground contamination plumes. The electrical resistance tomography technology measures soil electrical resistance between two electrodes. If a fluid contaminated with electrolytes is introduced into the soil, the soil resistance is expected to drop. By using an array of measurement electrodes in several boreholes, the areal extent of contamination can be estimated. At the Hanford Site, the purpose of the testing is to determine if the electrical resistance tomography technology can be used in the vicinity of large underground metal tanks without the metal tank interfering with the test. It is anticipated that the electrical resistance tomography technology will provide a method for accurately detecting leaks from the bottom of underground tanks, such as the Hanford Site single-shell tanks.

State Waste Discharge Permit Application: Electric resistance tomography testing

International Nuclear Information System (INIS)

1994-04-01

This permit application documentation is for a State Waste Discharge Permit issued in accordance with requirements of Washington Administrative Code 173-216. The activity being permitted is a technology test using electrical resistance tomography. The electrical resistance tomography technology was developed at Lawrence Livermore National Laboratory and has been used at other waste sites to track underground contamination plumes. The electrical resistance tomography technology measures soil electrical resistance between two electrodes. If a fluid contaminated with electrolytes is introduced into the soil, the soil resistance is expected to drop. By using an array of measurement electrodes in several boreholes, the areal extent of contamination can be estimated. At the Hanford Site, the purpose of the testing is to determine if the electrical resistance tomography technology can be used in the vicinity of large underground metal tanks without the metal tank interfering with the test. It is anticipated that the electrical resistance tomography technology will provide a method for accurately detecting leaks from the bottom of underground tanks, such as the Hanford Site single-shell tanks

High frequency of a single nucleotide substitution (c.-6-180T>G) of the canine MDR1/ABCB1 gene associated with phenobarbital-resistant idiopathic epilepsy in Border Collie dogs.

Science.gov (United States)

Mizukami, Keijiro; Yabuki, Akira; Chang, Hye-Sook; Uddin, Mohammad Mejbah; Rahman, Mohammad Mahbubur; Kushida, Kazuya; Kohyama, Moeko; Yamato, Osamu

2013-01-01

A single nucleotide substitution (c.-6-180T>G) associated with resistance to phenobarbital therapy has been found in the canine MDR1/ABCB1 gene in Border Collies with idiopathic epilepsy. In the present study, a PCR-restriction fragment length polymorphism assay was developed for genotyping this mutation, and a genotyping survey was carried out in a population of 472 Border Collies in Japan to determine the current allele frequency. The survey demonstrated the frequencies of the T/T wild type, T/G heterozygote, and G/G mutant homozygote to be 60.0%, 30.3%, and 9.8%, respectively, indicating that the frequency of the mutant G allele is extremely high (24.9%) in Border Collies. The results suggest that this high mutation frequency of the mutation is likely to cause a high prevalence of phenobarbital-resistant epilepsy in Border Collies.

Spatially resolved resistivity near the vortex lattice phase transition in Bi 2Sr 2CaCu 2O 8+δ single crystals

Science.gov (United States)

Berseth, V.; Indenbom, M. V.; van der Beek, C. J.; D'Anna, G.; Benoit, W.

1997-08-01

Using a multiterminal contact configuration, we investigate the local variations of the resistivity drop near the vortex lattice first order phase transition in a very homogeneous Bi2Sr2CaCu2O8+δ (BSCCO) single crystal.

A multicopy suppressor screening approach as a means to identify antibiotic resistance determinant candidates in Yersinia pestis

Directory of Open Access Journals (Sweden)

Moy Richard L

2008-07-01

Full Text Available Abstract Background Yersinia pestis is the causative agent of plague and a potential agent of bioterrorism and biowarfare. The plague biothreat and the emergence of multidrug-resistant plague underscore the need to increase our understanding of the intrinsic potential of Y. pestis for developing antimicrobial resistance and to anticipate the mechanisms of resistance that may emerge in Y. pestis. Identification of Y. pestis genes that, when overexpressed, are capable of reducing antibiotic susceptibility is a useful strategy to expose genes that this pathogen may rely upon to evolve antibiotic resistance via a vertical modality. In this study, we explored the use of a multicopy suppressor, Escherichia coli host-based screening approach as a means to expose antibiotic resistance determinant candidates in Y. pestis. Results We constructed a multicopy plasmid-based, Y. pestis genome-wide expression library of nearly 16,000 clones in E. coli and screened the library for suppressors of the antimicrobial activity of ofloxacin, a fluoroquinolone antibiotic. The screen permitted the identification of a transcriptional regulator-encoding gene (robAYp that increased the MIC99 of ofloxacin by 23-fold when overexpressed from a multicopy plasmid in Y. pestis. Additionally, we found that robAYp overexpression in Y. pestis conferred low-level resistance to many other antibiotics and increased organic solvent tolerance. Overexpression of robAYp also upregulated the expression of several efflux pumps in Y. pestis. Conclusion Our study provides proof of principle for the use of multicopy suppressor screening based on the tractable and easy-to-manipulate E. coli host as a means to identify antibiotic resistance determinant candidates of Y. pestis.

Non-p-glycoprotein-mediated multidrug resistance in detransformed rat cells selected for resistance to methylglyoxal bis(guanylhydrazone).

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Weber, J M; Sircar, S; Horvath, J; Dion, P

1989-11-01

Three independent variants (G2, G4, G5), resistant to methylglyoxal bis(guanylhydrazone), an anticancer drug, have been isolated by single step selection from an adenovirus-transformed rat brain cell line (1). These variants display selective cross-resistance to several natural product drugs of dissimilar structure and action. Multidrug resistance has recently been shown to be caused by overexpression of the membrane-associated p-glycoprotein, most often caused by amplification of the mdr gene. Several types of experiments were conducted to determine whether the observed drug resistance in our cell lines could be due to changes at the mdr locus. The following results were obtained: (a) the mdr locus was not amplified; (b) transcription of the mdr gene and p-glycoprotein synthesis were not increased; (c) multidrug resistance cell lines, which carry an amplified mdr locus, were not cross-resistant to methylglyoxal bis(guanylhydrazone); (d) verapamil did not reverse the resistance of G cells or mdr cells to methylglyoxal bis(guanylhydrazone), nor that of G cells to vincristine; and (e) methylglyoxal bis(guanylhydrazone) resistance was recessive and depended on a block to drug uptake, as opposed to mdr cells which are dominant and express increased drug efflux. The results obtained suggest that the drug resistance in the G2, G4, and G5 cells was atypical and may be due to a mechanism distinct from that mediated by the mdr locus.

Characterization of Plasmid-Mediated Quinolone Resistance Determinants in High-Level Quinolone-Resistant Enterobacteriaceae Isolates from the Community: First Report of qnrD Gene in Algeria.

Science.gov (United States)

Yanat, Betitera; Machuca, Jesús; Díaz-De-Alba, Paula; Mezhoud, Halima; Touati, Abdelaziz; Pascual, Álvaro; Rodríguez-Martínez, José-Manuel

2017-01-01

The objective was to assess the prevalence of plasmid-mediated quinolone resistance (PMQR)-producing isolates in a collection of quinolone-resistant Enterobacteriaceae of community origin isolated in Bejaia, Algeria. A total of 141 nalidixic acid-resistant Enterobacteriaceae community isolates were collected in Bejaia (Northern Algeria) and screened for PMQR genes using polymerase chain reaction (PCR). For PMQR-positive strains, antimicrobial susceptibility testing was performed by broth microdilution and disk diffusion. Mutations in the quinolone resistance-determining regions of the target genes, gyrA and parC, were detected with a PCR-based method and sequencing. Southern blotting, conjugation and transformation assays and molecular typing by pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing were also performed. The prevalence of PMQR-producing Enterobacteriaceae isolates was 13.5% (19/141); 11 of these isolates produced Aac(6')-Ib-cr and 8 were qnr-positive (4 qnrB1-like, 2 qnrS1-like, and 2 qnrD1-like), including the association with aac(6')-Ib-cr gene in three cases. PMQR gene transfer by conjugation was successful in 6 of 19 isolates tested. PFGE revealed that most of the PMQR-positive Escherichia coli isolates were unrelated, except for two groups comprising two and four isolates, respectively, including the virulent multidrug-resistant clone E. coli ST131 that were clonally related. Our findings indicate that PMQR determinants are prevalent in Enterobacteriaceae isolates from the community studied. We describe the first report of the qnrD gene in Algeria.

Genetic determinants of antifungal resistance in Candida species ...

African Journals Online (AJOL)

In the previous decades, it has been an increase in cases of resistance to antifungal agents used in the prophylaxis and treatment of infections caused by Candida species. The emergence of resistance to drug classes, it is usually explained by genome alterations ranging from point mutations to gain or loss of whole ...

NOVEL ANTIBIOTIC RESISTANCE DETERMINANTS FROM AGRICULTURAL SOIL EXPOSED TO ANTIBIOTICS WIDELY USED IN HUMAN MEDICINE AND ANIMAL FARMING.

Science.gov (United States)

Lau, Calvin Ho-Fung; van Engelen, Kalene; Gordon, Stephen; Renaud, Justin; Topp, Edward

2017-06-16

Antibiotic resistance has emerged globally as one of the biggest threats to human and animal health. Although the excessive use of antibiotics is recognized for accelerating the selection for resistance, there is a growing body of evidence suggesting that natural environments are "hotspots" for the development of both ancient and contemporary resistance mechanisms. Given that pharmaceuticals can be entrained onto agricultural land through anthropogenic activities, this could be a potential driver for the emergence and dissemination of resistance in soil bacteria. Using functional metagenomics, we interrogated the "resistome" of bacterial communities found in a collection of Canadian agricultural soil, some of which had been receiving antibiotics widely used in human medicine (macrolides) or food animal production (sulfamethazine, chlortetracycline and tylosin) for up to 16 years. Of the 34 new antibiotic resistance genes (ARGs) recovered, the majority were predicted to encode for (multi)drug efflux systems, while a few share little to no homology with established resistance determinants. We characterized several novel gene products, including putative enzymes that can confer high-level resistance against aminoglycosides, sulfonamides, and broad range of beta-lactams, with respect to their resistance mechanisms and clinical significance. By coupling high-resolution proteomics analysis with functional metagenomics, we discovered an unusual peptide, PPP AZI 4 , encoded within an alternative open-reading frame not predicted by bioinformatics tools. Expression of the proline-rich PPP AZI 4 can promote resistance against different macrolides but not other ribosomal-targeting antibiotics, implicating a new macrolide-specific resistance mechanism that could be fundamentally linked to the evolutionary design of this peptide. IMPORTANCE Antibiotic resistance is a clinical phenomenon with an evolutionary link to the microbial pangenome. Genes and protogenes encoding for

Adding bevacizumab to single agent chemotherapy for the treatment of platinum-resistant recurrent ovarian cancer: A cost effectiveness analysis of the AURELIA trial.

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Wysham, Weiya Z; Schaffer, Elisabeth M; Coles, Theresa; Roque, Dario R; Wheeler, Stephanie B; Kim, Kenneth H

2017-05-01

AURELIA, a randomized phase III trial of adding bevacizumab (B) to single agent chemotherapy (CT) for the treatment of platinum-resistant recurrent ovarian cancer, demonstrated improved progression free survival (PFS) in the B+CT arm compared to CT alone. We aimed to evaluate the cost effectiveness of adding B to CT in the treatment of platinum-resistant recurrent ovarian cancer. A decision tree model was constructed to evaluate the cost effectiveness of adding bevacizumab (B) to single agent chemotherapy (CT) based on the arms of the AURELIA trial. Costs, quality-adjusted life years (QALYs), and progression free survival (PFS) were modeled over fifteen months. Model inputs were extracted from published literature and public sources. Incremental cost effectiveness ratios (ICERs) per QALY gained and ICERs per progression free life year saved (PF-LYS) were calculated. One-way sensitivity analyses were performed to evaluate the robustness of results. The ICER associated with B+CT is $410,455 per QALY gained and $217,080 per PF-LYS. At a willingness to pay (WTP) threshold of $50,000/QALY, adding B to single agent CT is not cost effective for this patient population. Even at a WTP threshold of $100,000/QALY, B+CT is not cost effective. These findings are robust to sensitivity analyses. Despite gains in QALY and PFS, the addition of B to single agent CT for treatment of platinum-resistant recurrent ovarian cancer is not cost effective. Benefits, risks, and costs associated with treatment should be taken into consideration when prescribing chemotherapy for this patient population. Copyright © 2017 Elsevier Inc. All rights reserved.

DETERMINATION OF THE ISSUE CONCERNING THE LIFT RESISTANCE FACTOR OF LIGHTWEIGHT CAR

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A. O. Shvets

2015-10-01

Full Text Available Purpose. The analytical study of the connection between the longitudinal force, acting on the light-weight car, lateral and vertical forces of interaction in the contact zone «wheel – rail» with the lift resistance factor value is to provide a simple relationships between them. Methodology. Research was conducted by the method of mathematical modeling of loading the freight car when driving at different speeds on straight and curved sections of a track. Findings. Even in the absence of «lift» accordingly the classical train stability theory, as the hinge-rod system, the presence of the longitudinal compressive forces may become a factor provoking cars derailment. The main reason of wheel climbing on rails is the combination of processes of dynamic interaction between the hunting vehicle and the track with simultaneous action of longitudinal compressive forces, and not the destabilization of train as a hingedrod system. To assess the impact of the longitudinal forces value on the lift resistance factor there are presented the calculation results for the empty gondola car motion, model No. 12-532, on 250 m radius curve with 150 mm rise and cross starting of car underframe relating to the track axis in 50 mm guiding section. The calculations were made in such a curve excluding the inertial forces from outstanding acceleration and taking into account the unbalanced acceleration with the permissible speed of 65 km/h. Originality. This study provides the technique of determining the lift resistance factor by longitudinal forces, which is somewhat different from the standard one, as well as evaluates impact of rolling stock speed on this factor. Practical value. The authors clarify the current method of determining the lift resistance factor by longitudinal forces and assess the impact of rolling stock speed on the value of this factor. From these studies one can conclude that because of cars hunting their lift is possible even when the train as

Molecular characterization and determination of antimicrobial resistance of Mycoplasma gallisepticum isolated from chickens.

Science.gov (United States)

Pakpinyo, Somsak; Sasipreeyajan, Jiroj

2007-11-15

In this study, three consecutive approaches of molecular characterization, determination of minimum inhibitory concentration (MIC) and antimicrobial tested on Mycoplasma gallisepticum (MG) isolated from chicken farms were investigated. These approaches were conducted between 2004 and 2005 to 134 MG samples collected from five different regions of the intensive farming area of Thailand. Twenty MG isolates and four reference strains including S6, F, ts-11, and 6/85 were classified according to Random Amplification of Polymorphic DNA (RAPD) patterns prior to the antimicrobial tests. These isolates exhibited 5 different genotypes (A-E). Consequently, MG isolates representing each genotype were tested on 11 registered antibiotics. The levels of MIC were determined. Three antibiotics, doxycycline (0.20 microg/ml), tiamulin (0.10 microg/ml), and tylosin (0.33 microg/ml), gave the least MICs among all effective drugs. Break point comparisons of each antimicrobial suggested that the MG isolates were most sensitive to lincomycin, oxytetracycline, tiamulin, and tylosin. Some MG isolates had an intermediate effect on josamycin and were resistant to enrofloxacin and erythromycin. Our results also indicated that MG isolated and collected from the region and nearby districts had similar RAPD patterns showing properties of antimicrobial resistance. The RAPD patterns may imply the frequent use of antibiotics and a resistant strain of MG. This is the first report of genetic characterization using RAPD reflected by the levels of MIC against MG. The information is useful to plan for prophylactic and therapeutic impacts on the poultry industry especially in the area of intensive use of antibiotics.

CMOS-based active RC sinusoidal oscillator with four-phase quadrature outputs and single-resistance-controlled (SRC) tuning laws

OpenAIRE

Lahiri, Abhirup; Herencsár, Norbert

2012-01-01

This paper proposes a very compact CMOS realization of active RC sinusoidal oscillator capable of generating four quadrature voltage outputs. The oscillator is based on the cascade of lossless and lossy integrators in loop. The governing laws for the condition of oscillation (CO) and the frequency of oscillation (FO) are single-resistance-controlled (SRC) and which allow independent FO tuning. Unlike previously reported SRC-based sinusoidal oscillators based on the active building block (ABB)...

Resistance gene expression determines the in vitro chemosensitivity of non-small cell lung cancer (NSCLC)

International Nuclear Information System (INIS)

Glaysher, Sharon; Modi, Paul; Rahamim, Joe; Smith, Mark E; Amer, Khalid; Addis, Bruce; Poole, Matthew; Narayanan, Ajit; Gulliford, Tim J; Andreotti, Peter E; Cree, Ian A; Yiannakis, Dennis; Gabriel, Francis G; Johnson, Penny; Polak, Marta E; Knight, Louise A; Goldthorpe, Zoe; Peregrin, Katharine; Gyi, Mya

2009-01-01

NSCLC exhibits considerable heterogeneity in its sensitivity to chemotherapy and similar heterogeneity is noted in vitro in a variety of model systems. This study has tested the hypothesis that the molecular basis of the observed in vitro chemosensitivity of NSCLC lies within the known resistance mechanisms inherent to these patients' tumors. The chemosensitivity of a series of 49 NSCLC tumors was assessed using the ATP-based tumor chemosensitivity assay (ATP-TCA) and compared with quantitative expression of resistance genes measured by RT-PCR in a Taqman Array™ following extraction of RNA from formalin-fixed paraffin-embedded (FFPE) tissue. There was considerable heterogeneity between tumors within the ATP-TCA, and while this showed no direct correlation with individual gene expression, there was strong correlation of multi-gene signatures for many of the single agents and combinations tested. For instance, docetaxel activity showed some dependence on the expression of drug pumps, while cisplatin activity showed some dependence on DNA repair enzyme expression. Activity of both drugs was influenced more strongly still by the expression of anti- and pro-apoptotic genes by the tumor for both docetaxel and cisplatin. The doublet combinations of cisplatin with gemcitabine and cisplatin with docetaxel showed gene expression signatures incorporating resistance mechanisms for both agents. Genes predicted to be involved in known mechanisms drug sensitivity and resistance correlate well with in vitro chemosensitivity and may allow the definition of predictive signatures to guide individualized chemotherapy in lung cancer

Buprofezin susceptibility survey, resistance selection and preliminary determination of the resistance mechanism in Nilaparvata lugens (Homoptera: Delphacidae).

Science.gov (United States)

Wang, Yanhua; Gao, Congfen; Xu, Zhiping; Zhu, Yu Cheng; Zhang, Jiushuang; Li, Wenhong; Dai, Dejiang; Lin, Youwei; Zhou, Weijun; Shen, Jinliang

2008-10-01

Buprofezin has been used for many years to control Nilaparvata lugens (Stål). Assessment of susceptibility change in the insect is essential for maintaining control efficiency and resistance management. Eleven-year surveys showed that most field populations were susceptible before 2004. However, substantially higher levels of resistance (up to 28-fold) were found in most of the rice fields in China after 2004. A field population was collected and periodically selected for buprofezin resistance in the laboratory. After 65 generations (56 were selected), the colony successfully obtained 3599-fold resistance to buprofezin. Synergism tests showed that O,O-diethyl-O-phenyl phosphorothioate (SV1), piperonyl butoxide (PBO) and diethyl maleate (DEM) increased buprofezin toxicity in the resistant strain by only 1.5-1.6 fold, suggesting that esterases, P450-monooxygenases and glutathione S-transferases had no substantial effect on buprofezin resistance development. The results from this study indicate that N. lugens has the potential to develop high resistance to buprofezin. A resistance management program with rotation of buprofezin and other pesticides may efficiently delay or slow down resistance development in the insect. Further investigation is also necessary to understand the resistance mechanisms in N. lugens.

Inheritance and Bulked Segregant Analysis of Leaf Rust and Stem Rust Resistance in Durum Wheat Genotypes.

Science.gov (United States)

Aoun, Meriem; Kolmer, James A; Rouse, Matthew N; Chao, Shiaoman; Bulbula, Worku Denbel; Elias, Elias M; Acevedo, Maricelis

2017-12-01

Leaf rust, caused by Puccinia triticina, and stem rust, caused by P. graminis f. sp. tritici, are important diseases of durum wheat. This study determined the inheritance and genomic locations of leaf rust resistance (Lr) genes to P. triticina race BBBQJ and stem rust resistance (Sr) genes to P. graminis f. sp. tritici race TTKSK in durum accessions. Eight leaf-rust-resistant genotypes were used to develop biparental populations. Accessions PI 192051 and PI 534304 were also resistant to P. graminis f. sp. tritici race TTKSK. The resulting progenies were phenotyped for leaf rust and stem rust response at seedling stage. The Lr and Sr genes were mapped in five populations using single-nucleotide polymorphisms and bulked segregant analysis. Five leaf-rust-resistant genotypes carried single dominant Lr genes whereas, in the remaining accessions, there was deviation from the expected segregation ratio of a single dominant Lr gene. Seven genotypes carried Lr genes different from those previously characterized in durum. The single dominant Lr genes in PI 209274, PI 244061, PI387263, and PI 313096 were mapped to chromosome arms 6BS, 2BS, 6BL, and 6BS, respectively. The Sr gene in PI 534304 mapped to 6AL and is most likely Sr13, while the Sr gene in PI 192051 could be uncharacterized in durum.

Evaluation of Fine Aggregate Morphology by Image Method and Its Effect on Skid-Resistance of Micro-Surfacing.

Science.gov (United States)

Xiao, Yue; Wang, Feng; Cui, Peide; Lei, Lei; Lin, Juntao; Yi, Mingwei

2018-05-29

Micro-surfacing is a widely used pavement preventive maintenance technology used all over the world, due to its advantages of fast construction, low maintenance cost, good waterproofness, and skid-resistance performance. This study evaluated the fine aggregate morphology and surface texture of micro-surfacing by AIMS (aggregate image measurement system), and explored the effect of aggregate morphology on skid-resistance of single-grade micro-surfacing. Sand patch test and British pendulum test were also used to detect skid-resistance for comparison with the image-based method. Wet abrasion test was used to measure skid-resistance durability for feasibility verification of single-grade micro-surfacing. The results show that the effect of Form2D on the skid-resistance of micro-surfacing is much stronger than that of angularity. Combining the feasibility analysis of durability and skid-resistance, 1.18⁻2.36 grade micro-surfacing meets the requirements of durability and skid-resistance at the same time. This study also determined that, compared with British pendulum test, the texture result obtained by sand patch test fits better with results of image method.

Antibiotic resistance determinants and genetic analysis of Salmonella enterica isolated from food in Morocco.

Science.gov (United States)

Murgia, Manuela; Bouchrif, Brahim; Timinouni, Mohammed; Al-Qahtani, Ahmed; Al-Ahdal, Mohammed N; Cappuccinelli, Pietro; Rubino, Salvatore; Paglietti, Bianca

2015-12-23

Antimicrobial-resistant non-typhoidal Salmonella (NTS) are an important cause of infection in Africa, but there is a lack of information on their molecular mechanisms of resistance and epidemiology. This study contributes to fill this gap through the characterization by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), plasmid profiling and analysis of antibiotic-resistance determinants of 94 Salmonella enterica strains isolated from food in Morocco. PFGE revealed considerable heterogeneity among the strains, showing 32 pulsotypes. MLST of strains representative of the different serovars evidenced 13 sequence types (STs), three of which were newly identified (ST1694, ST1768 and ST1818) and nine not previously reported in Morocco. Thirty-four strains harbored from one to four plasmids, of IncI1 group in S. Mbandaka, IncFIIA in S. Typhimurium, IncL/M in S. Hadar and S. Blockley. For the first time in Morocco an intact Salmonella Genomic Island 1 (SGI1) carrying the resistance genes aadA2, floR, tetG, blaPSE-1 and sul1 was detected in S. Typhimurium DT104. In serovar Hadar resistance to ampicillin, tetracycline and streptomycin was associated to blaTEM-1, tetA and strA genes respectively, whereas one mutation in gyrA (Asp87Asn) and one in parC (Thr54Ser) genes conferred resistance to nalidixic acid. These findings improve the information on foodborne Salmonella in Morocco, evidencing the presence of MDR strains potentially dangerous to humans, and provide useful data for future studies. Copyright © 2015 Elsevier B.V. All rights reserved.

Isolation and Determination of Antibiotic Resistance Patterns in Nontyphoid Salmonella spp isolated from chicken

Directory of Open Access Journals (Sweden)

Seyyedeh Hoorieh Fallah

2013-01-01

Full Text Available Background: Salmonellosis is one of the most common food borne diseases in industrial and developing countries. In recent years, an increase in antimicrobial drug resistance, among non-typhoid Salmonella spp has been observed. Objectives: The aim of this study was to isolate and determine antibiotic resistance pattern in non-typhoid Salmonella spp. Materials and Methods: This descriptive study was done on 100 samples of chickens collected from 196 retail markets and was examined for the presence of Salmonella using standard bacteriological procedures and stereotyping kit. Antimicrobial susceptibility testing was performed by disk diffusion methods according to the National Committee for Clinical Laboratory Standards (CLSI. The data were analyzed by using the SPSS software version 18. Result: Forty- four percent of samples were contaminated with Salmonella infection and 56% didn’t have any contamination. The stereotyping results showed that 34 of 44 isolates of Salmonella belonged to Salmonella infantis (79.5 %, one strain (2.3% of group C and 8 strain (18.2% of group D. However, all these strains were sensitive to Cefotaxime and Ciprofloxacin, and 100% were resistant to Nalidixic acid, Tetracyclin and Sterptomycin. The most common resistance pattern (34.1% was towards six antibiotics, and 6.8% of strains were resistant to at least three antibiotics. Conclusion: High levels of resistance to antibiotics that are used commonly for human and poultry can be a warning for our community health and this information must be used to form important strategies for improvement of infection control.

Prevalence and molecular characterization of pyrazinamide resistance among multidrug-resistant Mycobacterium tuberculosis isolates from Southern China.

Science.gov (United States)

Pang, Yu; Zhu, Damian; Zheng, Huiwen; Shen, Jing; Hu, Yan; Liu, Jie; Zhao, Yanlin

2017-11-06

Pyrazinamide (PZA) plays a unique role in the treatment for multidrug-resistant tuberculosis (MDR-TB) in both first- and second-line regimens. The aim of this study was to investigate the prevalence and molecular characterization of PZA resistance among MDR-TB isolates collected in Chongqing municipality. A total of 133 MDR-TB isolates were collected from the smear-positive tuberculosis patients who were registered at local TB dispensaries of Chongqing. PZA susceptibility testing was determined with a Bactec MGIT 960 system. In addition, the genes conferring for PZA resistance were screened by DNA sequencing. Of these 133 MDR-TB isolates, 83 (62.4%) were determined as PZA-resistant by MGIT 960. In addition, streptomycin- (83.1% vs. 56.0%, P < 0.01), ofloxacin- (51.8% vs. 18.0%, P < 0.01), kanamycin- (22.9% vs. 2.0%, P < 0.01), amikacin- (18.1% vs. 2.0%, P = 0.01), capromycin-resistance (12.0% vs. 2.0%, P = 0.05), were more frequently observed among PZA-resistant isolates compared with PZA-susceptible isolates. Sequence analysis revealed that 73 out of 83 (88.0%) MDR strains harbored a mutation located in the pncA gene, including 55 (75.3%, 55/73) of single nucleotide substitutions and 18 (24.7%, 18/73) of frameshift mutation, while no genetic mutation associated with PZA resistance was found in the rpsA gene. The pncA expression of strains harboring substitution from A to G at position -11 in the promoter region of pncA was significantly lower than that of H37Rv (P < 0.01). In conclusion, our data have demonstrated that the analysis of the pncA gene rather than rpsA gene provides rapid and accurate information regarding PZA susceptibility for MDR-TB isolates in Chongqing. In addition, loss of pncA expression caused by promoter mutation confers PZA resistance in MDR-TB isolates.

Insertion sequence transposition determines imipenem resistance in Acinetobacter baumannii.

Science.gov (United States)

Kuo, Han-Yueh; Chang, Kai-Chih; Liu, Chih-Chin; Tang, Chuan Yi; Peng, Jhih-Hua; Lu, Chia-Wei; Tu, Chi-Chao; Liou, Ming-Li

2014-10-01

This study employed genomewide analysis to investigate potential resistance mechanisms in Acinetobacter baumannii following imipenem exposure. Imipenem-selected mutants were generated from the imipenem-susceptible strain ATCC 17978 by multistep selection resistance. Antibiotic susceptibilities were examined, and the selected mutants originated from the ATCC 17978 strain were confirmed by pulsed-field gel electrophoresis. The genomic sequence of a resistant mutant was analyzed using a next-generation sequencing platform, and genetic recombination was further confirmed by PCR. The result showed that phenotypic resistance was observed with carbapenem upon exposure to various concentrations of imipenem. Genomewide analysis showed that ISAba1 transposition was initiated by imipenem exposure at concentrations up to 0.5 mg/L. Transposition of ISAba1 upstream of blaOXA-95 was detected in all the selected mutants. The expression of blaOXA-95 was further analyzed by quantitative PCR, and the results demonstrated that a 200-fold increase in gene expression was required for resistance to imipenem. This study concluded that imipenem exposure at a concentration of 0.5 mg/L mediated the transposition of ISAba1 upstream of the blaOXA-95 gene and resulted in the overexpression of blaOXA-95 gene, which may play a major role in the resistance to imipenem in A. baumannii.

Engineering task plan for determining breathing rates in single shell tanks using tracer gas

International Nuclear Information System (INIS)

Andersen, J.A.

1997-01-01

The testing of single shell tanks to determine breathing rates. Inert tracer gases helium, and sulfur hexafluoride will be injected into the tanks AX-103, BY-105, C-107 and U-103. Periodic samples will be taken over a three month interval to determine actual headspace breathing rates

A technique for the determination of center of gravity and rolling resistance for tilt-seat wheelchairs.

Science.gov (United States)

Lemaire, E D; Lamontagne, M; Barclay, H W; John, T; Martel, G

1991-01-01

A balance platform setup was defined for use in the determination of the center of gravity in the sagittal plane for a wheelchair and patient. Using the center of gravity information, measurements from the wheelchair and patient (weight, tire coefficients of friction), and various assumptions (constant speed, level-concrete surface, patient-wheelchair system is a rigid body), a method for estimating the rolling resistance for a wheelchair was outlined. The center of gravity and rolling resistance techniques were validated against criterion values (center of gravity error = 1 percent, rolling resistance root mean square error = 0.33 N, rolling resistance Pearson correlation coefficient = 0.995). Consistent results were also obtained from a test dummy and five subjects. Once the center of gravity is known, it is possible to evaluate the stability of a wheelchair (in terms of tipping over) and the interaction between the level of stability and rolling resistance. These quantitative measures are expected to be of use in the setup of wheelchairs with a variable seat angle and variable wheelbase length or when making comparisons between different wheelchairs.

Bacterial Multidrug Efflux Pumps: Much More Than Antibiotic Resistance Determinants.

Science.gov (United States)

Blanco, Paula; Hernando-Amado, Sara; Reales-Calderon, Jose Antonio; Corona, Fernando; Lira, Felipe; Alcalde-Rico, Manuel; Bernardini, Alejandra; Sanchez, Maria Blanca; Martinez, Jose Luis

2016-02-16

Bacterial multidrug efflux pumps are antibiotic resistance determinants present in all microorganisms. With few exceptions, they are chromosomally encoded and present a conserved organization both at the genetic and at the protein levels. In addition, most, if not all, strains of a given bacterial species present the same chromosomally-encoded efflux pumps. Altogether this indicates that multidrug efflux pumps are ancient elements encoded in bacterial genomes long before the recent use of antibiotics for human and animal therapy. In this regard, it is worth mentioning that efflux pumps can extrude a wide range of substrates that include, besides antibiotics, heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals or bacterial metabolites, among others. In the current review, we present information on the different functions that multidrug efflux pumps may have for the bacterial behaviour in different habitats as well as on their regulation by specific signals. Since, in addition to their function in non-clinical ecosystems, multidrug efflux pumps contribute to intrinsic, acquired, and phenotypic resistance of bacterial pathogens, the review also presents information on the search for inhibitors of multidrug efflux pumps, which are currently under development, in the aim of increasing the susceptibility of bacterial pathogens to antibiotics.

High Frequency of a Single Nucleotide Substitution (c.-6-180T>G of the Canine MDR1/ABCB1 Gene Associated with Phenobarbital-Resistant Idiopathic Epilepsy in Border Collie Dogs

Directory of Open Access Journals (Sweden)

Keijiro Mizukami

2013-01-01

Full Text Available A single nucleotide substitution (c.-6-180T>G associated with resistance to phenobarbital therapy has been found in the canine MDR1/ABCB1 gene in Border Collies with idiopathic epilepsy. In the present study, a PCR-restriction fragment length polymorphism assay was developed for genotyping this mutation, and a genotyping survey was carried out in a population of 472 Border Collies in Japan to determine the current allele frequency. The survey demonstrated the frequencies of the T/T wild type, T/G heterozygote, and G/G mutant homozygote to be 60.0%, 30.3%, and 9.8%, respectively, indicating that the frequency of the mutant G allele is extremely high (24.9% in Border Collies. The results suggest that this high mutation frequency of the mutation is likely to cause a high prevalence of phenobarbital-resistant epilepsy in Border Collies.

Antibiotic Resistance

DEFF Research Database (Denmark)

Munck, Christian

morbidity and mortality as well as an increase in the cost of treatment. Understanding how bacteria respond to antibiotic exposure gives the foundations for a rational approach to counteract antimicrobial resistance. In the work presented in this thesis, I explore the two fundamental sources...... of antimicrobial resistance: (1) adaptive mutations and (2) horizontal acquisition of resistance genes from antibiotic gene reservoirs. By studying the geno- and phenotypic changes of E. coli in response to single and drug-pair exposures, I uncover the evolutionary trajectories leading to adaptive resistance. I...... to rationally design drug combinations that limit the evolution of antibiotic resistance due to counteracting evolutionary trajectories. My results highlight that an in-depth knowledge about the genetic responses to the individual antimicrobial compounds enables the prediction of responses to drug combinations...

The Second-Generation Maturation Inhibitor GSK3532795 Maintains Potent Activity Toward HIV Protease Inhibitor-Resistant Clinical Isolates.

Science.gov (United States)

Ray, Neelanjana; Li, Tianbo; Lin, Zeyu; Protack, Tricia; van Ham, Petronella Maria; Hwang, Carey; Krystal, Mark; Nijhuis, Monique; Lataillade, Max; Dicker, Ira

2017-05-01

Protease inhibitor (PI)-resistant HIV-1 isolates with primary substitutions in protease (PR) and secondary substitutions in Gag could potentially exhibit cross-resistance to maturation inhibitors. We evaluated the second-generation maturation inhibitor, GSK3532795, for activity toward clinical isolates with genotypic and phenotypic characteristics associated with PI resistance (longitudinal). Longitudinal clinical isolates from 15 PI-treated patients and 7 highly PI-resistant (nonlongitudinal) viruses containing major and minor PI resistance-associated mutations were evaluated for GSK3532795 sensitivity. Phenotypic sensitivity was determined using the PhenoSense Gag/PR assay (Monogram Biosciences) or in-house single- and multiple-cycle assays. Changes from baseline [CFB; ratio of post- to pre-treatment FC-IC50 (fold-change in IC50 versus wild-type virus)] Monogram (11 patients)] and 1.5 (1.0-2.2) [single-cycle (4 patients)]. The 2 post-PI treatment samples showing GSK3532795 CFB >3 (Monogram) were retested using single- and multiple-cycle assays. Neither sample had meaningful sensitivity changes in the multiple-cycle assay. Gag changes were not associated with an increased GSK3532795 CFB. GSK3532795 maintained antiviral activity against PI-resistant isolates with emergent PR and/or Gag mutations. This finding supports continued development of GSK3532795 in treatment-experienced patients with or without previous PI therapy.

Accuracy of single count methods of WL determination for open-pit uranium mines

International Nuclear Information System (INIS)

Solomon, S.B.; Kennedy, K. N.

1983-01-01

A study of single count methods of WL determination was made using a database respresentative of Australian open pit uranium mine conditions. The aim of the study was to check the existence of the optimum time delay coresponding to the Rolle method, to determine the accuracy of the conversion factor for Australian conditions and to examine any systematic use of data bases of representative radon daughter concentration

Accurate Detection of Methicillin-Resistant Staphylococcus aureus in Mixtures by Use of Single-Bacterium Duplex Droplet Digital PCR.

Science.gov (United States)

Luo, Jun; Li, Junhua; Yang, Hang; Yu, Junping; Wei, Hongping

2017-10-01

Accurate and rapid identification of methicillin-resistant Staphylococcus aureus (MRSA) is needed to screen MRSA carriers and improve treatment. The current widely used duplex PCR methods are not able to differentiate MRSA from coexisting methicillin-susceptible S. aureus (MSSA) or other methicillin-resistant staphylococci. In this study, we aimed to develop a direct method for accurate and rapid detection of MRSA in clinical samples from open environments, such as nasal swabs. The new molecular assay is based on detecting the cooccurrence of nuc and mecA markers in a single bacterial cell by utilizing droplet digital PCR (ddPCR) with the chimeric lysin ClyH for cell lysis. The method consists of (i) dispersion of an intact single bacterium into nanoliter droplets, (ii) temperature-controlled release of genomic DNA (gDNA) by ClyH at 37°C, and (iii) amplification and detection of the markers ( nuc and mecA ) using standard TaqMan chemistries with ddPCR. Results were analyzed based on MRSA index ratios used for indicating the presence of the duplex-positive markers in droplets. The method was able to achieve an absolute limit of detection (LOD) of 2,900 CFU/ml for MRSA in nasal swabs spiked with excess amounts of Escherichia coli , MSSA, and other mecA -positive bacteria within 4 h. Initial testing of 104 nasal swabs showed that the method had 100% agreement with the standard culture method, while the normal duplex qPCR method had only about 87.5% agreement. The single-bacterium duplex ddPCR assay is rapid and powerful for more accurate detection of MRSA directly from clinical specimens. Copyright © 2017 American Society for Microbiology.

Environmental pollution by antibiotics and by antibiotic resistance determinants

International Nuclear Information System (INIS)

Martinez, Jose Luis

2009-01-01

Antibiotics are among the most successful drugs used for human therapy. However, since they can challenge microbial populations, they must be considered as important pollutants as well. Besides being used for human therapy, antibiotics are extensively used for animal farming and for agricultural purposes. Residues from human environments and from farms may contain antibiotics and antibiotic resistance genes that can contaminate natural environments. The clearest consequence of antibiotic release in natural environments is the selection of resistant bacteria. The same resistance genes found at clinical settings are currently disseminated among pristine ecosystems without any record of antibiotic contamination. Nevertheless, the effect of antibiotics on the biosphere is wider than this and can impact the structure and activity of environmental microbiota. Along the article, we review the impact that pollution by antibiotics or by antibiotic resistance genes may have for both human health and for the evolution of environmental microbial populations. - The article reviews the current knowledge on the effects that pollution by antibiotics and antibiotic resistance genes may have for the microbiosphere.

Environmental pollution by antibiotics and by antibiotic resistance determinants

Energy Technology Data Exchange (ETDEWEB)

Martinez, Jose Luis, E-mail: jlmtnez@cnb.csic.e [Departamento de Biotecnologia Microbiana, Centro Nacional de Biotecnologia, Consejo Superior de Investigaciones Cientificas, Darwin 3, Cantoblanco, 28049 Madrid, and CIBERESP (Spain)

2009-11-15

Antibiotics are among the most successful drugs used for human therapy. However, since they can challenge microbial populations, they must be considered as important pollutants as well. Besides being used for human therapy, antibiotics are extensively used for animal farming and for agricultural purposes. Residues from human environments and from farms may contain antibiotics and antibiotic resistance genes that can contaminate natural environments. The clearest consequence of antibiotic release in natural environments is the selection of resistant bacteria. The same resistance genes found at clinical settings are currently disseminated among pristine ecosystems without any record of antibiotic contamination. Nevertheless, the effect of antibiotics on the biosphere is wider than this and can impact the structure and activity of environmental microbiota. Along the article, we review the impact that pollution by antibiotics or by antibiotic resistance genes may have for both human health and for the evolution of environmental microbial populations. - The article reviews the current knowledge on the effects that pollution by antibiotics and antibiotic resistance genes may have for the microbiosphere.

Determination of the mass-ratio distribution, I: single-lined spectroscopic binary stars

NARCIS (Netherlands)

Hogeveen, S.J.

1992-01-01

For single-lined spectroscopic binary stars (sbi), the mass ratio q = Msec=Mprim is calculated from the mass function f(m), which is determined from observations. For statistical investigations of the mass-ratio distribution, the term sin^3 i, that remains in the cubic equation from which q is

Antimicrobial resistance determinants in Staphylococcus spp. recovered from birds of prey in Portugal.

Science.gov (United States)

Sousa, Margarida; Silva, Nuno; Igrejas, Gilberto; Silva, Filipe; Sargo, Roberto; Alegria, Nuno; Benito, Daniel; Gómez, Paula; Lozano, Carmen; Gómez-Sanz, Elena; Torres, Carmen; Caniça, Manuela; Poeta, Patrícia

2014-07-16

Antibiotic resistance among wild animals represent an emerging public health concern. The objective of this study was to analyze the staphylococcal nasal microbiota in birds of prey and their content in antimicrobial resistance determinants. Nasal samples from 16 birds of prey were collected, swabs were dipped and incubated into BHI broth [6.5% NaCl] and later seeded on manitol salt agar and oxacillin-resistance screening agar base media. Staphylococcal colonies were isolated from both media and were identified by biochemical and molecular methods. Susceptibility testing to 18 antimicrobial agents was performed by disk-diffusion method. Six of the 16 tested animals carried staphylococci (37.5%) and 7 isolates of the following species were recovered: Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Staphylococcus sciuri rodentium, Staphylococcus cohnii urealitycum, and Staphylococcus gallinarum. The S. aureus isolate was penicillin-resistant (with blaZ gene) but methicillin-susceptible and was ascribed to spa-type t012, sequence-type ST30 and agr-type III. The S. epidermidis isolate carried blaZ, mecA, mrs(A/B), mphC, tet(K), drfA, and fusC genes, ica operon, and was typed as ST35. The genes ant6'-Ia, tet(K), tet(L), dfrG, cat221, cat194, and cat223 were detected in S. saprophyticus or S. gallinarum isolates. Birds of prey seem to be a natural reservoir of S. aureus and coagulase-negative staphylococci resistant to multiple antibiotics. Due to the convergence between habitats, the contact between wildlife, other animals and humans is now more common and this involves an increased possibility of interchange of these microorganisms in the different ecosystems. Copyright © 2014 Elsevier B.V. All rights reserved.

Protease resistance of infectious prions is suppressed by removal of a single atom in the cellular prion protein.

Science.gov (United States)

Leske, Henning; Hornemann, Simone; Herrmann, Uli Simon; Zhu, Caihong; Dametto, Paolo; Li, Bei; Laferriere, Florent; Polymenidou, Magdalini; Pelczar, Pawel; Reimann, Regina Rose; Schwarz, Petra; Rushing, Elisabeth Jane; Wüthrich, Kurt; Aguzzi, Adriano

2017-01-01

Resistance to proteolytic digestion has long been considered a defining trait of prions in tissues of organisms suffering from transmissible spongiform encephalopathies. Detection of proteinase K-resistant prion protein (PrPSc) still represents the diagnostic gold standard for prion diseases in humans, sheep and cattle. However, it has become increasingly apparent that the accumulation of PrPSc does not always accompany prion infections: high titers of prion infectivity can be reached also in the absence of protease resistant PrPSc. Here, we describe a structural basis for the phenomenon of protease-sensitive prion infectivity. We studied the effect on proteinase K (PK) resistance of the amino acid substitution Y169F, which removes a single oxygen atom from the β2-α2 loop of the cellular prion protein (PrPC). When infected with RML or the 263K strain of prions, transgenic mice lacking wild-type (wt) PrPC but expressing MoPrP169F generated prion infectivity at levels comparable to wt mice. The newly generated MoPrP169F prions were biologically indistinguishable from those recovered from prion-infected wt mice, and elicited similar pathologies in vivo. Surprisingly, MoPrP169F prions showed greatly reduced PK resistance and density gradient analyses showed a significant reduction in high-density aggregates. Passage of MoPrP169F prions into mice expressing wt MoPrP led to full recovery of protease resistance, indicating that no strain shift had taken place. We conclude that a subtle structural variation in the β2-α2 loop of PrPC affects the sensitivity of PrPSc to protease but does not impact prion replication and infectivity. With these findings a specific structural feature of PrPC can be linked to a physicochemical property of the corresponding PrPSc.

Resistant plasmid profile analysis of multidrug resistant Escherichia ...

African Journals Online (AJOL)

Background: Multi-drug resistant Escherichia coli has become a major threat and cause of many urinary tract infections (UTIs) in Abeokuta, Nigeria. Objectives: This study was carried out to determine the resistant plasmids of multidrug resistant Escherichia coli isolated from (Urinary tract infections)UTIs in Abeokuta.

Determination of chlorinated hydrocarbons in single and multi component test gases

Energy Technology Data Exchange (ETDEWEB)

Giese, U.; Stenner, H. (Paderborn Univ. (Gesamthochschule) (Germany, F.R.). Angewandte Chemie); Ludwig, E.; Kettrup, A. (Paderborn Univ. (Gesamthochschule) (Germany, F.R.). Angewandte Chemie Gesellschaft fuer Strahlen- und Umweltforschung mbH Muenchen, Neuherberg (Germany, F.R.). Inst. fuer Oekologische Chemie)

1990-11-01

For comparing the efficiency of active and diffusive sampling methods two diffusive samplers with different properties were used to determine chlorinated hydrocarbons (CH{sub 2}Cl{sub 2}, CHCl{sub 3}, CCl{sub 4}) in single and multi component test gas mixtures. One of the chosen diffusive samplers can also be used for active sampling. In general, good correlations of all tested methods could be observed in the direct comparison of active and diffusive sampling and in the determination of the efficiencies. During the application of active and diffusive sampling methods in multi component test gases of the analytes possible interferences could not be ascertained. (orig.).

Single-photon tomographic determination of regional cerebral blood flow in epilepsy

International Nuclear Information System (INIS)

Bonte, F.J.; Devous, M.D. Sr.; Stokely, E.M.; Homan, R.W.

1983-01-01

Using a single-photon emission computed tomographic scanner (SPECT) the authors determined regional cerebral blood flow (rCBF) with inhaled xenon-133, a noninvasive procedure. Studies were performed in 40 normal individuals, and these were compared with rCBF determinations in 51 patients with seizure disorders. Although positive results were obtained in 15 of 16 patients with mass lesions, the group of principal interest comprised 25 patients suffering from ''temporal lobe'' epilepsy. Only one of these had a positive x-ray computed tomogram, but 16 had positive findings on rCBF study. These findings included increased local blood flow in the ictal state and reduced flow interictally

Characterization of the etiological structure and genotypically determined phenotypic resistance to carbapenems of infectious complications leading pathogens in critically ill patients

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O. A. Nazarchuk

2018-06-01

Full Text Available The aim is to investigate the genotypically determined phenotypic resistance to carbapenems of gram-negative microorganisms isolated from patients with critical states. Material and methods. Microbiological etiology of infectious complications in critically ill patients (n = 726 was investigated. In total, during the years 2011–2016, 933 clinical strains of infectious complications pathogens from patients with severe burns (n = 435 and from patients treated in intensive care units (n = 291 were isolated and identified. The sensitivity of microorganisms clinical isolates to antibiotics was investigated by means of the standard microbiological methods. In gram-negative bacteria resistant to carbapenems, a molecular genetic study of mechanisms of resistance, determined by the presence of VIM genes, was carried out using the method of real-time polymerase chain reaction. Results. Studies have shown that gram-negative microorganisms (Acinetobacter spp. – 36.3 %, P. aeruginosa – 31.7 %, Enterobacter spp. – 13.5 %, Proteus spp. – 7.9 %, E. coli – 3.8 %; K. pneumoniae – 3.6 %, etc. account for a significant part of infectious complications pathogens structure in critically ill patients. A. baumannii strains (67 % have expressed phenotypic resistance to most antibiotics, in particular to carbapenems (up to 63.2 %. Poly-antibiotic resistance was also found in P. aeruginosa (72 %, and above one the 3rd part of strains of this pathogen was found to have phenotypic resistance to carbapenems. In-depth study of molecular genetic determinants of the resistance mechanism to β-lactam antibiotics among clinical strains of gram-negative bacteria there was proved VIM-induced resistance to carbapenems in A. baumannii, P. aeruginosa, P. mirabilis. Conclusions. Enterobacteriaceae and non-fermenting gram-negative microorganisms (P. aeruginosa, P. mirabilis, A. baumannii, which are the leading causative agents of infectious complications in patients with

Resistance gene expression determines the in vitro chemosensitivity of non-small cell lung cancer (NSCLC

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Amer Khalid

2009-08-01

Full Text Available Abstract Background NSCLC exhibits considerable heterogeneity in its sensitivity to chemotherapy and similar heterogeneity is noted in vitro in a variety of model systems. This study has tested the hypothesis that the molecular basis of the observed in vitro chemosensitivity of NSCLC lies within the known resistance mechanisms inherent to these patients' tumors. Methods The chemosensitivity of a series of 49 NSCLC tumors was assessed using the ATP-based tumor chemosensitivity assay (ATP-TCA and compared with quantitative expression of resistance genes measured by RT-PCR in a Taqman Array™ following extraction of RNA from formalin-fixed paraffin-embedded (FFPE tissue. Results There was considerable heterogeneity between tumors within the ATP-TCA, and while this showed no direct correlation with individual gene expression, there was strong correlation of multi-gene signatures for many of the single agents and combinations tested. For instance, docetaxel activity showed some dependence on the expression of drug pumps, while cisplatin activity showed some dependence on DNA repair enzyme expression. Activity of both drugs was influenced more strongly still by the expression of anti- and pro-apoptotic genes by the tumor for both docetaxel and cisplatin. The doublet combinations of cisplatin with gemcitabine and cisplatin with docetaxel showed gene expression signatures incorporating resistance mechanisms for both agents. Conclusion Genes predicted to be involved in known mechanisms drug sensitivity and resistance correlate well with in vitro chemosensitivity and may allow the definition of predictive signatures to guide individualized chemotherapy in lung cancer.

Radiation-resistant camera tube

International Nuclear Information System (INIS)

Kuwahata, Takao; Manabe, Sohei; Makishima, Yasuhiro

1982-01-01

It was a long time ago that Toshiba launched on manufacturing black-and-white radiation-resistant camera tubes employing nonbrowning face-plate glass for ITV cameras used in nuclear power plants. Now in compliance with the increasing demand in nuclear power field, the Company is at grips with the development of radiation-resistant single color-camera tubes incorporating a color-stripe filter for color ITV cameras used under radiation environment. Herein represented are the results of experiments on characteristics of materials for single color-camera tubes and prospects for commercialization of the tubes. (author)

Measurement of Dynamic Resistance in Resistance Spot Welding

DEFF Research Database (Denmark)

Wu, Pei; Lu, J.; Zhang, Wenqi

2007-01-01

is influenced by inductive noise caused by the high welding current. In this study, the dynamic resistance is determined by measuring the voltage at primary side and current at secondary side. This increases the accuracy of measurement because of higher signal-noise ratio, and allows to apply to in-process......The conventional methods of determining the dynamic resistance were mostly done by measuring the voltage and current at secondary side of transformer in resistance welding machines, in which the measuring set-up normally interferes with the movement of electrode, and the measuring precision...

A nonlinear HP-type complementary resistive switch

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Paul K. Radtke

2016-05-01

Full Text Available Resistive Switching (RS is the change in resistance of a dielectric under the influence of an external current or electric field. This change is non-volatile, and the basis of both the memristor and resistive random access memory. In the latter, high integration densities favor the anti-serial combination of two RS-elements to a single cell, termed the complementary resistive switch (CRS. Motivated by the irregular shape of the filament protruding into the device, we suggest a nonlinearity in the resistance-interpolation function, characterized by a single parameter p. Thereby the original HP-memristor is expanded upon. We numerically simulate and analytically solve this model. Further, the nonlinearity allows for its application to the CRS.

A nonlinear HP-type complementary resistive switch

Science.gov (United States)

Radtke, Paul K.; Schimansky-Geier, Lutz

2016-05-01

Resistive Switching (RS) is the change in resistance of a dielectric under the influence of an external current or electric field. This change is non-volatile, and the basis of both the memristor and resistive random access memory. In the latter, high integration densities favor the anti-serial combination of two RS-elements to a single cell, termed the complementary resistive switch (CRS). Motivated by the irregular shape of the filament protruding into the device, we suggest a nonlinearity in the resistance-interpolation function, characterized by a single parameter p. Thereby the original HP-memristor is expanded upon. We numerically simulate and analytically solve this model. Further, the nonlinearity allows for its application to the CRS.

Draft Genome Sequence of Neisseria gonorrhoeae Strain NG_869 with Penicillin, Tetracycline and Ciprofloxacin Resistance Determinants Isolated from Malaysia

OpenAIRE

Ang, Geik Yong; Yu, Choo Yee; Yong, Delicia Ann; Cheong, Yuet Meng; Yin, Wai-Fong; Chan, Kok-Gan

2016-01-01

Gonorrhea is a sexually transmitted infection caused by Neisseria gonorrhoeae and the increasing reports of multidrug-resistant gonococcal isolates are a global public health care concern. Herein, we report the genome sequence of N. gonorrhoeae strain NG_869 isolated from Malaysia which may provide insights into the drug resistance determinants in gonococcal bacteria.

Identifying the optimal resistive load for complex training in male rugby players.

Science.gov (United States)

Comyns, Thomas M; Harrison, Andrew J; Hennessy, Liam; Jensen, Randall L

2007-01-01

Alternating a resistance exercise with a plyometric exercise is referred to as "complex training". In this study, we examined the effect of various resistive loads on the biomechanics of performance of a fast stretch-shortening cycle activity to determine if an optimal resistive load exists for complex training. Twelve elite rugby players performed three drop jumps before and after three back squat resistive loads of 65%, 80%, and 93% of a single repetition maximum (1-RM) load. All drop jumps were performed on a specially constructed sledge and force platform apparatus. Flight time, ground contact time, peak ground reaction force, reactive strength index, and leg stiffness were the dependent variables. Repeated-measures analysis of variance found that all resistive loads reduced (P benefit performance. However, it is unknown if these acute changes will produce any long-term adaptations to muscle function.

Determination of the Resistance of Cone-Shaped Solid Electrodes

DEFF Research Database (Denmark)

Frandsen, Henrik Lund; Hendriksen, Peter Vang; Koch, Søren

2017-01-01

during processing can be avoided. Newman's formula for current constriction in the electrolyte is then used to deduce the active contact area based on the ohmic resistance of the cell, and from this the surface specific electro-catalytic activity. However, for electrode materials with low electrical......A cone-shaped electrode pressed into an electrolyte can with advantage be utilized to characterize the electro-catalytic properties of the electrode, because it is less dependent on the electrode microstructure than e.g. thin porous composite electrodes, and reactions with the electrolyte occurring...... conductivity (like Ce1-xPrxO2-δ), the resistance of the cell is significantly influenced by the ohmic resistance of the cone electrode, wherefore it must be included. In this work the ohmic resistance of a cone is modelled analytically based on simplified geometries. The two analytical models only differ...

Benchmark Evaluation of True Single Molecular Sequencing to Determine Cystic Fibrosis Airway Microbiome Diversity

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Andrea Hahn

2018-05-01

Full Text Available Cystic fibrosis (CF is an autosomal recessive disease associated with recurrent lung infections that can lead to morbidity and mortality. The impact of antibiotics for treatment of acute pulmonary exacerbations on the CF airway microbiome remains unclear with prior studies giving conflicting results and being limited by their use of 16S ribosomal RNA sequencing. Our primary objective was to validate the use of true single molecular sequencing (tSMS and PathoScope in the analysis of the CF airway microbiome. Three control samples were created with differing amounts of Burkholderia cepacia, Pseudomonas aeruginosa, and Prevotella melaninogenica, three common bacteria found in cystic fibrosis lungs. Paired sputa were also obtained from three study participants with CF before and >6 days after initiation of antibiotics. Antibiotic resistant B. cepacia and P. aeruginosa were identified in concurrently obtained respiratory cultures. Direct sequencing was performed using tSMS, and filtered reads were aligned to reference genomes from NCBI using PathoScope and Kraken and unique clade-specific marker genes using MetaPhlAn. A total of 180–518 K of 6–12 million filtered reads were aligned for each sample. Detection of known pathogens in control samples was most successful using PathoScope. In the CF sputa, alpha diversity measures varied based on the alignment method used, but similar trends were found between pre- and post-antibiotic samples. PathoScope outperformed Kraken and MetaPhlAn in our validation study of artificial bacterial community controls and also has advantages over Kraken and MetaPhlAn of being able to determine bacterial strains and the presence of fungal organisms. PathoScope can be confidently used when evaluating metagenomic data to determine CF airway microbiome diversity.

Antibiotic Resistance in Staphylococcus aureus and Coagulase Negative Staphylococci Isolated from Goats with Subclinical Mastitis

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Salvatore Virdis

2010-01-01

Full Text Available Antimicrobial resistance patterns and gene coding for methicillin resistance (mecA were determined in 25 S. aureus and 75 Coagulase Negative Staphylococci (CNS strains isolates from half-udder milk samples collected from goats with subclinical mastitis. Fourteen (56.0% S. aureus and thirty-one (41.3% CNS isolates were resistant to one or more antimicrobial agents. S. aureus showed the highest resistance rate against kanamycin (28.0%, oxytetracycline (16.0%, and ampicillin (12.0%. The CNS tested were more frequently resistant to ampicillin (36.0% and kanamycin (6.7%. Multiple antimicrobial resistance was observed in eight isolates, and one Staphylococcus epidermidis was found to be resistant to six antibiotics. The mecA gene was not found in any of the tested isolates. Single resistance against β-lactamics or aminoglicosides is the most common trait observed while multiresistance is less frequent.

Frequency of Antiretroviral Resistance Mutations among Infants Exposed to Single-Dose Nevirapine and Short Course Maternal Antiretroviral Regimens: ACTG A5207.

Science.gov (United States)

Hitti, Jane; Halvas, Elias K; Zheng, Lu; Panousis, Constantinos G; Kabanda, Joseph; Taulo, Frank; Kumarasamy, Nagalingeswaran; Pape, Jean William; Lalloo, Umesh; Sprenger, Heather; Klingman, Karin L; Chan, Ellen S; McMahon, Deborah; Mellors, John W

2014-11-01

Intrapartum single-dose nevirapine (sdNVP) reduces HIV-1 perinatal transmission but selects NVP resistance among mothers and infants. We evaluated the frequency of antiretroviral resistance among infants with intrauterine HIV-1 infection exposed to sdNVP and maternal antenatal or breastfeeding antiretroviral therapy. This analysis included 429 infants from sub-Saharan Africa, India and Haiti whose 422 mothers received sdNVP plus maternal study treatment. At entry mothers had CD4>250/μL and were ART-naïve except for antenatal ZDV per local standard of care. Maternal study treatment started intrapartum and included ZDV/3TC, TDF/FTC or LPV/r for 7 or 21 days in a randomized factorial design. Infants received sdNVP study treatment and ZDV if local standard of care. Infant HIV RNA or DNA PCR and samples for genotype were obtained at birth and weeks 2, 4 and 12; infants who ever breast-fed were also tested at weeks 16, 24, 48 and 96. Samples from HIV-1-infected infants were tested for drug resistance by population genotype (ViroSeq). NVP or NRTI resistance mutations were assessed using the IAS-USA mutation list. Perinatal HIV-1 transmission occurred in 17 (4.0%) infants including 12 intrauterine infections. Resistance mutations were detected among 5 (42%) intrauterine-infected infants; of these, 3 had mutations conferring resistance to NVP alone, 1 had resistance to NRTI alone, and 1 had dual-class resistance mutations. Among the 2 infants with NRTI mutations, one (K70R) was likely maternally transmitted and one (K65R) occurred in the context of breastfeeding exposure to maternal antiretroviral therapy. Infants with intrauterine HIV infection are at risk of acquiring resistance mutations from exposure to maternal antiretroviral medications intrapartum and/or during breastfeeding. New approaches are needed to lower the risk of antiretroviral resistance in these infants.

Clonality, virulence and antimicrobial resistance of enteroaggregative Escherichia coli from Mirzapur, Bangladesh.

Science.gov (United States)

Chattaway, Marie Anne; Day, Michaela; Mtwale, Julia; White, Emma; Rogers, James; Day, Martin; Powell, David; Ahmad, Marwa; Harris, Ross; Talukder, Kaisar Ali; Wain, John; Jenkins, Claire; Cravioto, Alejandro

2017-10-01

This study investigates the virulence and antimicrobial resistance in association with common clonal complexes (CCs) of enteroaggregative Escherichia coli (EAEC) isolated from Bangladesh. The aim was to determine whether specific CCs were more likely to be associated with putative virulence genes and/or antimicrobial resistance. The presence of 15 virulence genes (by PCR) and susceptibility to 18 antibiotics were determined for 151 EAEC isolated from cases and controls during an intestinal infectious disease study carried out between 2007-2011 in the rural setting of Mirzapur, Bangladesh (Kotloff KL, Blackwelder WC, Nasrin D, Nataro JP, Farag TH et al.Clin Infect Dis 2012;55:S232-S245). These data were then analysed in the context of previously determined serotypes and clonal complexes defined by multi-locus sequence typing. Overall there was no association between the presence of virulence or antimicrobial resistance genes in isolates of EAEC from cases versus controls. However, when stratified by clonal complex (CC) one CC associated with cases harboured more virulence factors (CC40) and one CC harboured more resistance genes (CC38) than the average. There was no direct link between the virulence gene content and antibiotic resistance. Strains within a single CC had variable virulence and resistance gene content indicating independent and multiple gene acquisitions over time. In Bangladesh, there are multiple clonal complexes of EAEC harbouring a variety of virulence and resistance genes. The emergence of two of the most successful clones appeared to be linked to either increased virulence (CC40) or antimicrobial resistance (CC38), but increased resistance and virulence were not found in the same clonal complexes.

Determination of a Wear Initiation Cycle by using a Contact Resistance Measurement in Nuclear Fuel Fretting

International Nuclear Information System (INIS)

Lee, Young Ho; Kim, Hyung Kyu

2008-01-01

In nuclear fuel fretting, the improving of the contact condition with a modified spring shape is a useful method for increasing the wear resistance of the nuclear fuel rod. This is because the fretting wear resistance between the fuel rod and grid spring is mainly affected by the grid spring shape rather than the environment, the contact modes, etc. In addition, the wear resistance is affected by the wear debris behavior between contact surfaces. So, it is expected that the wear initiation of each spring shape should be determined in order to evaluate a wear resistance. However, it is almost impossible to measure the wear behavior in contact surfaces on a real time basis because the contact surfaces are always hidden. Besides, the results of the worn surface observation after the fretting wear tests are restricted to archive the information on the wear debris behavior and the formation mechanism of the wear scar. In order to evaluate the wear behavior during the fretting wear tests, it is proposed that the contact resistance measurement is a useful method for examining the wear initiation cycle and modes. Generally, fretting wear damages are rapidly progressed by a localized plastic deformation between the contact surfaces, crack initiation and fracture of the deformed surface with a strain hardening difference between a surface and a subsurface and finally a detachment of wear debris. After this, wear debris is easily oxidized by frictional heat, test environment, etc. At this time, a small amount of electric current applied between the contact surfaces will be influenced by the wear debris, which could be an obstacle to an electric current flow. So, it is possible to archive the information on the wear behavior by measuring the contact resistance. In order to determine the wear initiation cycle during the fretting wear tests, in this study, fretting wear tests have been performed by applying a constant electric current in room temperature air

Pediatric - specific Antimicrobial Resistance Patterns of Urinary Tract Infections: A Single - Centre Experience from Turkey

OpenAIRE

Kandur, Yasar; Ozden, Sevinc; Buyukkaragoz, Bahar

2016-01-01

Objectives: Antimicrobial resistance of the causative microorganisms of pediatric urinary tract infection (UTI) is a growing problem. The aim of this study is to determine the changing pattern of antibiotic susceptibility in UTIs in an outpatient setting. Methods: We retrospectively reviewed the medical records of pediatric patients with UTI who were followed-up in our center between January-2014 and May-2015. Results: One hundred and seventy-one patients (M...

Effect of electrode shape on grounding resistances - Part 1

DEFF Research Database (Denmark)

Ingeman-Nielsen, Thomas; Tomaskovicova, Sonia; Dahlin, Torleif

2016-01-01

Electrode grounding resistance is a major factor affecting measurement quality in electric resistivity tomography (ERT) measurements for cryospheric applications. Still, little information is available on grounding resistances in the geophysical literature, mainly because it is difficult to measure....... The focus-one protocol is a new method for estimating single electrode grounding resistances by measuring the resistance between a single electrode in an ERT array and all the remaining electrodes connected in parallel. For large arrays, the measured resistance is dominated by the grounding resistance...... of the electrode under test, the focus electrode. We have developed an equivalent circuit model formulation for the resistance measured when applying the focus-one protocol. Our model depends on the individual grounding resistances of the electrodes of the array, the mutual resistances between electrodes...

Evaluation of Fine Aggregate Morphology by Image Method and Its Effect on Skid-Resistance of Micro-Surfacing

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Yue Xiao

2018-05-01

Full Text Available Micro-surfacing is a widely used pavement preventive maintenance technology used all over the world, due to its advantages of fast construction, low maintenance cost, good waterproofness, and skid-resistance performance. This study evaluated the fine aggregate morphology and surface texture of micro-surfacing by AIMS (aggregate image measurement system, and explored the effect of aggregate morphology on skid-resistance of single-grade micro-surfacing. Sand patch test and British pendulum test were also used to detect skid-resistance for comparison with the image-based method. Wet abrasion test was used to measure skid-resistance durability for feasibility verification of single-grade micro-surfacing. The results show that the effect of Form2D on the skid-resistance of micro-surfacing is much stronger than that of angularity. Combining the feasibility analysis of durability and skid-resistance, 1.18–2.36 grade micro-surfacing meets the requirements of durability and skid-resistance at the same time. This study also determined that, compared with British pendulum test, the texture result obtained by sand patch test fits better with results of image method.

Distribution of virulence determinants among antimicrobial-resistant and antimicrobial-susceptible Escherichia coli implicated in urinary tract infections.

Science.gov (United States)

Stephenson, Sam; Brown, P D

2016-01-01

Uropathogenic Escherichia coli (UPEC) rely on the correlation of virulence expression with antimicrobial resistance to persist and cause severe urinary tract infections (UTIs). We assessed the virulence pattern and prevalence among UPEC strains susceptible and resistant to multiple antimicrobial classes. A total of 174 non-duplicate UPEC strains from patients with clinically significant UTIs were analysed for susceptibility to aminoglycoside, antifolate, cephalosporin, nitrofuran and quinolone antibiotics for the production of extended-spectrum β-lactamases and for the presence of six virulence determinants encoding adhesins (afimbrial, Type 1 fimbriae, P and S-fimbriae) and toxins (cytotoxic necrotising factor and haemolysin). Relatively high resistance rates to nalidixic acid, ciprofloxacin, cephalothin and trimethoprim-sulfamethoxazole (82%, 78%, 62% and 59%, respectively) were observed. Fourteen distinct patterns were identified for the virulence determinants such as afaBC, cnfI, fimH, hylA, papEF and sfaDE. The toxin gene, cnfI (75.3%), was the second most prevalent marker to the adhesin, fimH (97.1%). The significant association of sfaDE/hylA (P < 0.01) among antimicrobial resistant and susceptible strains was also observed notwithstanding an overall greater occurrence of virulence factors among the latter. This study provides a snapshot of UPEC complexity in Jamaica and highlights the significant clonal heterogeneity among strains. Such outcomes emphasise the need for evidence-based strategies in the effective management and control of UTIs.

Detection of mutations in quinolone-resistant determining regions in ...

African Journals Online (AJOL)

Yomi

2012-01-16

Jan 16, 2012 ... Since the use of fluoroquinolone antibiotic in clinical practice was introduced about two decades ago, quinolone-resistant E. coli strains .... containing dehydrated antibiotics (Merlin Diagnostika, Germany) in two–fold dilution. .... alterations in parC play fundamental role in developing high level of resistance ...

New test procedure to determine fuel's knock resistance; Neues Kraftstoffpruefverfahren zur Bestimmung der Klopffestigkeit

Energy Technology Data Exchange (ETDEWEB)

Huber, Karl [Hochschule Ingolstadt (Germany). Thermodynamik und Verbrennungsmotoren; Hauber, Johann; Raba, Andreas [Hochschule Ingolstadt (Germany). Inst. fuer Angewandte Forschung; Nell, Robert [Rofa Laboratory and Process Analyzers, Kritzendorf (Austria). Bereich Produktentwicklung

2013-07-15

Knock resistance is one of the most important quality features of gasoline that is determined by standardised motor test procedures. These procedures were developed more than 80 years ago and have been used nearly unchanged since then. During a four-year research project at Ingolstadt University of Applied Sciences, the procedures for determination of octane numbers were analysed in order to develop a new engine-based test method. (orig.)

QTL for white spot syndrome virus resistance and the sex-determining locus in the Indian black tiger shrimp (Penaeus monodon).

Science.gov (United States)

Robinson, Nicholas A; Gopikrishna, Gopalapillay; Baranski, Matthew; Katneni, Vinaya Kumar; Shekhar, Mudagandur S; Shanmugakarthik, Jayakani; Jothivel, Sarangapani; Gopal, Chavali; Ravichandran, Pitchaiyappan; Gitterle, Thomas; Ponniah, Alphis G

2014-08-28

Shrimp culture is a fast growing aquaculture sector, but in recent years there has been a shift away from tiger shrimp Penaeus monodon to other species. This is largely due to the susceptibility of P. monodon to white spot syndrome virus disease (Whispovirus sp.) which has impacted production around the world. As female penaeid shrimp grow more rapidly than males, mono-sex production would be advantageous, however little is known about genes controlling or markers associated with sex determination in shrimp. In this study, a mapped set of 3959 transcribed single nucleotide polymorphisms were used to scan the P. monodon genome for loci associated with resistance to white-spot syndrome virus and sex in seven full-sibling tiger shrimp families challenged with white spot syndrome virus. Linkage groups 2, 3, 5, 6, 17, 18, 19, 22, 27 and 43 were found to contain quantitative trait loci significantly associated with hours of survival after white spot syndrome virus infection (P shrimp.

Anisotropic Resistivities of Precisely Oxygen Controlled Single-Crystal Bi2Sr2CaCu2O8+δ: Systematic Study on ''Spin Gap'' Effect

International Nuclear Information System (INIS)

Watanabe, T.; Matsuda, A.; Fujii, T.; Matsuda, A.

1997-01-01

The in-plane resistivity ρ a (T) and the out-of-plane resistivity ρ c (T) have been systematically measured for Bi 2 Sr 2 CaCu 2 O 8+δ single crystals with their oxygen contents precisely controlled. In the underdoped region, deviation from T -linear in-plane resistivity, which evidences the opening of the spin gap, is clearly observed, while the out-of-plane resistivity is well reproduced by the activation-type phenomenological formula ρ c (T)=(a/T)exp (Δ/T)+c . In contrast to the YBa 2 Cu 3 O 7-δ system, we find that the onset of the semiconducting ρ c (T) does not coincide with the opening of the spin gap seen in the ρ a (T) in this Bi 2 Sr 2 CaCu 2 O 8+δ system. copyright 1997 The American Physical Society

Synergy against drug-resistant HIV-1 with the microbicide antiretrovirals, dapivirine and tenofovir, in combination.

Science.gov (United States)

Schader, Susan M; Colby-Germinario, Susan P; Schachter, Jordana R; Xu, Hongtao; Wainberg, Mark A

2011-08-24

To evaluate the candidate antiretroviral microbicide compounds, dapivirine (DAP) and tenofovir (TFV), alone and in combination against the transmission of wild-type and nonnucleoside reverse transcriptase inhibitor (NNRTI)-resistant HIV-1 from different subtypes. We determined single-drug efficacy of the RTIs, DAP and TFV, against subtype B and non-B wild-type and NNRTI-resistant HIV-1 in vitro. To assess breadth of activity, compounds were tested alone and in combination against wild-type and NNRTI-resistant subtype C primary HIV-1 isolates and complimentary clonal HIV-1 from subtypes B, C and CRF02_AG to control for viral variation. Early infection was quantified by counting light units emitted from TZM-bl cells less than 48-h postinfection. Combination ratios were based on drug inhibitory concentrations (IC(50)s) and combined effects were determined by calculating combination indices. Both candidate microbicide antiretrovirals demonstrated potent anti-NNRTI-resistant HIV-1 activity in vitro, albeit the combination protected better than the single-drug treatments. Of particular interest, the DAP with TFV combination exhibited synergy (50% combination index, CI(50) = 0.567) against subtype C NNRTI-resistant HIV-1, whereas additivity (CI(50) = 0.987) was observed against the wild-type counterpart from the same patient. The effect was not compounded by the presence of subdominant viral fractions, as experiments using complimentary clonal subtype C wild-type (CI(50) = 0.968) and NNRTI-resistant (CI(50) = 0.672) HIV-1, in lieu of the patient quasispecies, gave similar results. This study supports the notion that antiretroviral drug combinations may retain antiviral activity against some drug-resistant HIV-1 despite subtype classification and quasispecies diversity.

Synthesis and Single Crystal X-Ray Structure Determination of 3,3',5 ...

African Journals Online (AJOL)

Single crystal structure determination at 100 K revealed needle-like crystals in an orthorhombic crystal system. The asymmetric unit of the cell consists of an isolated chloride ion, one half of a tetrahedral [MnCl4]2- anion, a [H2Me4bpz]2+ dication and one half of a molecule of water. Keywords: Crystal Engineering, Hydrogen ...

Determination of Insulin Resistance and Beta Cell Function in Healthy Obese and Non-obese Individuals

International Nuclear Information System (INIS)

Kazmi, A.; Sattar, A.; Tariq, K. M.; Najamussahar; Hashim, R.; Almani, M. I.

2013-01-01

Objective: To determine insulin resistance and beta cell function in healthy obese and nonobese individuals of the local population. Study Design: Case control study. Place and Duration of Study: AFIP Rawalpindi in collaboration with department of medicine military hospital(MH) Rawalpindi, from Aug 2008 to Mar 2009. Methods: Eighty obese(n=40) and non-obese(n=40) subjects were selected by non-probability convenience sampling. Plasma insulin, glucose, and serum total cholestrol were estimated in fasting state. Insulin resistance was calculated by HOMA-IR and beta cell function by HOMA- equation. Results: Significant differences were observed between obese and non-obese individuals regarding insulin resistance, beta cell function, and BMI and serum total cholesterol. Mean insulin resistance in obese group was found to be 11.1 +- 5.1(range 7.0-16.2) and in non-obese group it was 0.9+-0.4 (range 0.5-1.3). This difference was highly significant (p=0.001). There was a highly significant difference between the two groups in term of beta cell function with mean rank 60.1 for obese group and 20.9 non obese groups (Asym sig. 2 tailed 0.000). Also the correlation (r = 0.064) between insulin resistance and beta cell function in obese group is highly significant (p = 0.000). Mean serum leptin levels were lower (6.3 ng/ml) in non-obese, and high (57.2 ng/ml) in the obese group. Conclusions: Insulin resistance is found higher in obese individuals. Beta cell function is significantly different between obese and non-obese groups. (author)

The Second-Generation Maturation Inhibitor GSK3532795 Maintains Potent Activity Toward HIV Protease Inhibitor–Resistant Clinical Isolates

Science.gov (United States)

Ray, Neelanjana; Li, Tianbo; Lin, Zeyu; Protack, Tricia; van Ham, Petronella Maria; Hwang, Carey; Krystal, Mark; Nijhuis, Monique; Lataillade, Max

2017-01-01

Background: Protease inhibitor (PI)-resistant HIV-1 isolates with primary substitutions in protease (PR) and secondary substitutions in Gag could potentially exhibit cross-resistance to maturation inhibitors. We evaluated the second-generation maturation inhibitor, GSK3532795, for activity toward clinical isolates with genotypic and phenotypic characteristics associated with PI resistance (longitudinal). Methods: Longitudinal clinical isolates from 15 PI-treated patients and 7 highly PI-resistant (nonlongitudinal) viruses containing major and minor PI resistance-associated mutations were evaluated for GSK3532795 sensitivity. Phenotypic sensitivity was determined using the PhenoSense Gag/PR assay (Monogram Biosciences) or in-house single- and multiple-cycle assays. Changes from baseline [CFB; ratio of post- to pre-treatment FC-IC50 (fold-change in IC50 versus wild-type virus)] Monogram (11 patients)] and 1.5 (1.0–2.2) [single-cycle (4 patients)]. The 2 post-PI treatment samples showing GSK3532795 CFB >3 (Monogram) were retested using single- and multiple-cycle assays. Neither sample had meaningful sensitivity changes in the multiple-cycle assay. Gag changes were not associated with an increased GSK3532795 CFB. Conclusions: GSK3532795 maintained antiviral activity against PI-resistant isolates with emergent PR and/or Gag mutations. This finding supports continued development of GSK3532795 in treatment-experienced patients with or without previous PI therapy. PMID:28234686

Determination of selenium in BCR single cell protein via destructive neutron activation analysis

International Nuclear Information System (INIS)

Goeij, J.J.M. de; Zegers, C.

1978-10-01

The amount of selenium in single cell protein (SCP), a product of BP Research Centre at Sunbury-at-Thames, England, was determined by neutron activation analysis. The SCP-samples were irradiated in the reactor of the Interuniversity Reactor Institute at Delft, in a neutron flux of 1.0 x 10 13 n/cm 2 s for 24 hours. After chemical destruction of the samples the amount of selenium was determined by measuring the γ-peaks of selenium-75

Molecular screening of antibiotic-resistant determinants among ...

African Journals Online (AJOL)

In Nigeria, increase in bacterial resistance has been phenotypically established but due to high cost, few molecular studies ... ocomial opportunistic infections such as urinary tract .... Twelve (20%) of these MDR isolates were from children.

A Single Resistance Exercise Session Improves Aortic Endothelial Function in Hypertensive Rats

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Thaís de Oliveira Faria

Full Text Available Abstract Background: Physical exercise is an important tool for the improvement of endothelial function. Objective: To assess the effects of acute dynamic resistance exercise on the endothelial function of spontaneously hypertensive rats (SHR. Methods: Ten minutes after exercise, the aorta was removed to evaluate the expression of endothelial nitric oxide synthase (eNOS, phosphorylated endothelial nitric oxide synthase (p-eNOS1177 and inducible nitric oxide synthase (iNOS and to generate concentration-response curves to acetylcholine (ACh and to phenylephrine (PHE. The PHE protocol was also performed with damaged endothelium and before and after NG-nitro-L-arginine methyl ester (L-NAME and indomethacin administration. The maximal response (Emax and the sensitivity (EC50 to these drugs were evaluated. Results: ACh-induced relaxation increased in the aortic rings of exercised (Ex rats (Emax= -80 ± 4.6%, p < 0.05 when compared to those of controls (Ct (Emax = -50 ± 6.8%. The Emax to PHE was decreased following exercise conditions (95 ± 7.9%, p < 0.05 when compared to control conditions (120 ± 4.2%. This response was abolished after L-NAME administration or endothelial damage. In the presence of indomethacin, the aortic rings' reactivity to PHE was decreased in both groups (EC50= Ex -5.9 ± 0.14 vs. Ct -6.6 ± 0.33 log µM, p < 0.05 / Emax = Ex 9.5 ± 2.9 vs. Ct 17 ± 6.2%, p < 0.05. Exercise did not alter the expression of eNOS and iNOS, but increased the level of p-eNOS. Conclusion: A single resistance exercise session improves endothelial function in hypertensive rats. This response seems to be mediated by increased NO production through eNOS activation.

Realisations of single-resistance-controlled quadrature oscillators using a generalised current follower transconductance amplifier and a unity-gain voltage-follower

OpenAIRE

Herencsár, Norbert; Vrba, Kamil; Koton, Jaroslav; Lahiri, Abhirup

2010-01-01

This article presents realisations of single-resistance-controlled-oscillators (SRCOs) using the recently proposed modern active building block (ABB), namely the generalised current follower transconductance amplifier (GCFTA) and unity-gain voltage-follower (UGVF). The SRCO is made using reduced number of components: one GCFTA and one UGVF as the ABBs, two resistors and two grounded capacitors. The circuit offers the advantage of non-interactive control of condition of oscillation and frequen...

Improved annotation of antibiotic resistance determinants reveals microbial resistomes cluster by ecology.

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Gibson, Molly K; Forsberg, Kevin J; Dantas, Gautam

2015-01-01

Antibiotic resistance is a dire clinical problem with important ecological dimensions. While antibiotic resistance in human pathogens continues to rise at alarming rates, the impact of environmental resistance on human health is still unclear. To investigate the relationship between human-associated and environmental resistomes, we analyzed functional metagenomic selections for resistance against 18 clinically relevant antibiotics from soil and human gut microbiota as well as a set of multidrug-resistant cultured soil isolates. These analyses were enabled by Resfams, a new curated database of protein families and associated highly precise and accurate profile hidden Markov models, confirmed for antibiotic resistance function and organized by ontology. We demonstrate that the antibiotic resistance functions that give rise to the resistance profiles observed in environmental and human-associated microbial communities significantly differ between ecologies. Antibiotic resistance functions that most discriminate between ecologies provide resistance to β-lactams and tetracyclines, two of the most widely used classes of antibiotics in the clinic and agriculture. We also analyzed the antibiotic resistance gene composition of over 6000 sequenced microbial genomes, revealing significant enrichment of resistance functions by both ecology and phylogeny. Together, our results indicate that environmental and human-associated microbial communities harbor distinct resistance genes, suggesting that antibiotic resistance functions are largely constrained by ecology.

SOLUBILITY PREDICTION OF SULFONAMIDES AT VARIOUS TEMPERATURES USING A SINGLE DETERMINATION

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JALAL HANAEE

2005-04-01

Full Text Available Solubility of sulphamethoxazole, sulphisoxazole and sulphasalazine in six solvents namely water,methanol, ethanol, 1-propanol, acetone and chloroform were determined at 15, 25, 37 and 45 °C. Two models derived from the Hildebrand solubility approach are proposed for solubility prediction at different temperatures using a single determination. The experimental data of the present work as well as data gathered from the literature have been employed to investigate the accuracy and prediction capability of the proposed models. The overall percent deviations between the predicted and experimental values were 10.78 and 14.63% which were comparable to those of the classical two and three parameter models. The proposed models were much superior to the two pure predictive models i.e., the ones which do not require experimental solubility determination, as the overall percent deviations produced by the latter models were 150.09 and 161.00%.

Tyrosine kinase inhibitors: Multi-targeted or single-targeted?

Science.gov (United States)

Broekman, Fleur; Giovannetti, Elisa; Peters, Godefridus J

2011-02-10

Since in most tumors multiple signaling pathways are involved, many of the inhibitors in clinical development are designed to affect a wide range of targeted kinases. The most important tyrosine kinase families in the development of tyrosine kinase inhibitors are the ABL, SCR, platelet derived growth factor, vascular endothelial growth factor receptor and epidermal growth factor receptor families. Both multi-kinase inhibitors and single-kinase inhibitors have advantages and disadvantages, which are related to potential resistance mechanisms, pharmacokinetics, selectivity and tumor environment. In different malignancies various tyrosine kinases are mutated or overexpressed and several resistance mechanisms exist. Pharmacokinetics is influenced by interindividual differences and differs for two single targeted inhibitors or between patients treated by the same tyrosine kinase inhibitor. Different tyrosine kinase inhibitors have various mechanisms to achieve selectivity, while differences in gene expression exist between tumor and stromal cells. Considering these aspects, one type of inhibitor can generally not be preferred above the other, but will depend on the specific genetic constitution of the patient and the tumor, allowing personalized therapy. The most effective way of cancer treatment by using tyrosine kinase inhibitors is to consider each patient/tumor individually and to determine the strategy that specifically targets the consequences of altered (epi)genetics of the tumor. This strategy might result in treatment by a single multi kinase inhibitor for one patient, but in treatment by a couple of single kinase inhibitors for other patients.

Determination of the specific resistance of individual freestanding ZnO nanowires with the low energy electron point source microscope

Energy Technology Data Exchange (ETDEWEB)

Weber, Dirk Henning; Beyer, Andre; Voelkel, Berthold; Goelzhaeuser, Armin [Physik Supramolekularer Systeme, Universitaet Bielefeld (Germany); Schlenker, Eva; Bakin, Andrey; Waag, Andreas [Institut fuer Halbleitertechnik, Technische Universitaet Braunschweig (Germany)

2008-07-01

A low energy electron point source (LEEPS) microscope is used to determine the electrical conductivity of individual freestanding ZnO nanowires in UHV. The nanowires were contacted with a manipulation tip and I-V curves were taken at different wire lengths. From those, the specific resistance was calculated and separated from the contact resistance. By comparing the specific resistances of ZnO nanowires with diameters between 1100 and 48 nm, a large surface contribution for the thin nanowires was found. A geometric model for separation between surface and bulk contributions is given. The results of electrical transport measurements on vapor phase grown ZnO nanowires are discussed, as well as the size dependence of the wire resistance.

Resistance Pattern and Molecular Characterization of Enterotoxigenic Escherichia coli (ETEC Strains Isolated in Bangladesh.

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Yasmin A Begum

Full Text Available Enterotoxigenic Escherichia coli (ETEC is a common cause of bacterial infection leading to acute watery diarrhea in infants and young children as well as in travellers to ETEC endemic countries. Ciprofloxacin is a broad-spectrum antimicrobial agent nowadays used for the treatment of diarrhea. This study aimed to characterize ciprofloxacin resistant ETEC strains isolated from diarrheal patients in Bangladesh.A total of 8580 stool specimens from diarrheal patients attending the icddr,b Dhaka hospital was screened for ETEC between 2005 and 2009. PCR and Ganglioside GM1- Enzyme Linked Immuno sorbent Assay (ELISA was used for detection of Heat labile (LT and Heat stable (ST toxins of ETEC. Antimicrobial susceptibilities for commonly used antibiotics and the minimum inhibitory concentration (MIC of nalidixic acid, ciprofloxacin and azithromycin were examined. DNA sequencing of representative ciprofloxacin resistant strains was performed to analyze mutations of the quinolone resistance-determining region of gyrA, gyrB, parC and parE. PCR was used for the detection of qnr, a plasmid mediated ciprofloxacin resistance gene. Clonal variations among ciprofloxacin resistant (CipR and ciprofloxacin susceptible (CipS strains were determined by Pulsed-field gel electrophoresis (PFGE.Among 1067 (12% ETEC isolates identified, 42% produced LT/ST, 28% ST and 30% LT alone. Forty nine percent (n = 523 of the ETEC strains expressed one or more of the 13 tested colonization factors (CFs as determined by dot blot immunoassay. Antibiotic resistance of the ETEC strains was observed as follows: ampicillin 66%, azithromycin 27%, ciprofloxacin 27%, ceftriazone 13%, cotrimaxazole 46%, doxycycline 44%, erythromycin 96%, nalidixic acid 83%, norfloxacin 27%, streptomycin 48% and tetracycline 42%. Resistance to ciprofloxacin increased from 13% in 2005 to 34% in 2009. None of the strains was resistant to mecillinam. The MIC of the nalidixic acid and ciprofloxacin of representative

Identification and characterization of two novel bla(KLUC resistance genes through large-scale resistance plasmids sequencing.

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Teng Xu

Full Text Available Plasmids are important antibiotic resistance determinant carriers that can disseminate various drug resistance genes among species or genera. By using a high throughput sequencing approach, two groups of plasmids of Escherichia coli (named E1 and E2, each consisting of 160 clinical E. coli strains isolated from different periods of time were sequenced and analyzed. A total of 20 million reads were obtained and mapped onto the known resistance gene sequences. As a result, a total of 9 classes, including 36 types of antibiotic resistant genes, were identified. Among these genes, 25 and 27 single nucleotide polymorphisms (SNPs appeared, of which 9 and 12 SNPs are nonsynonymous substitutions in the E1 and E2 samples. It is interesting to find that a novel genotype of bla(KLUC, whose close relatives, bla(KLUC-1 and bla(KLUC-2, have been previously reported as carried on the Kluyvera cryocrescens chromosome and Enterobacter cloacae plasmid, was identified. It shares 99% and 98% amino acid identities with Kluc-1 and Kluc-2, respectively. Further PCR screening of 608 Enterobacteriaceae family isolates yielded a second variant (named bla(KLUC-4. It was interesting to find that Kluc-3 showed resistance to several cephalosporins including cefotaxime, whereas bla(KLUC-4 did not show any resistance to the antibiotics tested. This may be due to a positively charged residue, Arg, replaced by a neutral residue, Leu, at position 167, which is located within an omega-loop. This work represents large-scale studies on resistance gene distribution, diversification and genetic variation in pooled multi-drug resistance plasmids, and provides insight into the use of high throughput sequencing technology for microbial resistance gene detection.

Disease resistance in Atlantic salmon (Salmo salar: coinfection of the intracellular bacterial pathogen Piscirickettsia salmonis and the sea louse Caligus rogercresseyi.

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Jean Paul Lhorente

Full Text Available BACKGROUND: Naturally occurring coinfections of pathogens have been reported in salmonids, but their consequences on disease resistance are unclear. We hypothesized that 1 coinfection of Caligus rogercresseyi reduces the resistance of Atlantic salmon to Piscirickettsia salmonis; and 2 coinfection resistance is a heritable trait that does not correlate with resistance to a single infection. METHODOLOGY: In total, 1,634 pedigreed Atlantic salmon were exposed to a single infection (SI of P. salmonis (primary pathogen or coinfection with C. rogercresseyi (secondary pathogen. Low and high level of coinfection were evaluated (LC = 44 copepodites per fish; HC = 88 copepodites per fish. Survival and quantitative genetic analyses were performed to determine the resistance to the single infection and coinfections. MAIN FINDINGS: C. rogercresseyi significantly increased the mortality in fish infected with P. salmonis (SI mortality = 251/545; LC mortality = 544/544 and HC mortality = 545/545. Heritability estimates for resistance to P. salmonis were similar and of medium magnitude in all treatments (h2SI = 0.23 ± 0.07; h2LC = 0.17 ± 0.08; h2HC = 0.24 ± 0.07. A large and significant genetic correlation with regard to resistance was observed between coinfection treatments (rg LC-HC = 0.99 ± 0.01 but not between the single and coinfection treatments (rg SI-LC = -0.14 ± 0.33; rg SI-HC = 0.32 ± 0.34. CONCLUSIONS/SIGNIFICANCE: C. rogercresseyi, as a secondary pathogen, reduces the resistance of Atlantic salmon to the pathogen P. salmonis. Resistance to coinfection of Piscirickettsia salmonis and Caligus rogercresseyi in Atlantic salmon is a heritable trait. The absence of a genetic correlation between resistance to a single infection and resistance to coinfection indicates that different genes control these processes. Coinfection of different pathogens and resistance to coinfection needs to be considered in future

Disease resistance in Atlantic salmon (Salmo salar): coinfection of the intracellular bacterial pathogen Piscirickettsia salmonis and the sea louse Caligus rogercresseyi.

Science.gov (United States)

Lhorente, Jean Paul; Gallardo, José A; Villanueva, Beatriz; Carabaño, María J; Neira, Roberto

2014-01-01

Naturally occurring coinfections of pathogens have been reported in salmonids, but their consequences on disease resistance are unclear. We hypothesized that 1) coinfection of Caligus rogercresseyi reduces the resistance of Atlantic salmon to Piscirickettsia salmonis; and 2) coinfection resistance is a heritable trait that does not correlate with resistance to a single infection. In total, 1,634 pedigreed Atlantic salmon were exposed to a single infection (SI) of P. salmonis (primary pathogen) or coinfection with C. rogercresseyi (secondary pathogen). Low and high level of coinfection were evaluated (LC = 44 copepodites per fish; HC = 88 copepodites per fish). Survival and quantitative genetic analyses were performed to determine the resistance to the single infection and coinfections. C. rogercresseyi significantly increased the mortality in fish infected with P. salmonis (SI mortality = 251/545; LC mortality = 544/544 and HC mortality = 545/545). Heritability estimates for resistance to P. salmonis were similar and of medium magnitude in all treatments (h2SI = 0.23 ± 0.07; h2LC = 0.17 ± 0.08; h2HC = 0.24 ± 0.07). A large and significant genetic correlation with regard to resistance was observed between coinfection treatments (rg LC-HC = 0.99 ± 0.01) but not between the single and coinfection treatments (rg SI-LC = -0.14 ± 0.33; rg SI-HC = 0.32 ± 0.34). C. rogercresseyi, as a secondary pathogen, reduces the resistance of Atlantic salmon to the pathogen P. salmonis. Resistance to coinfection of Piscirickettsia salmonis and Caligus rogercresseyi in Atlantic salmon is a heritable trait. The absence of a genetic correlation between resistance to a single infection and resistance to coinfection indicates that different genes control these processes. Coinfection of different pathogens and resistance to coinfection needs to be considered in future research on salmon farming, selective breeding and conservation.

Multidrug resistance 1 gene polymorphisms may determine Crohn's disease behavior in patients from Rio de Janeiro

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Ana Teresa P. Carvalho

2014-01-01

Full Text Available OBJECTIVES: Conflicting data from studies on the potential role of multidrug resistance 1 gene polymorphisms in inflammatory bowel disease may result from the analysis of genetically and geographically distinct populations. Here, we investigated whether multidrug resistance 1 gene polymorphisms are associated with inflammatory bowel diseases in patients from Rio de Janeiro. METHODS: We analyzed 123 Crohn's disease patients and 83 ulcerative colitis patients to determine the presence of the multidrug resistance 1 gene polymorphisms C1236T, G2677T and C3435T. In particular, the genotype frequencies of Crohn's disease and ulcerative colitis patients were analyzed. Genotype-phenotype associations with major clinical characteristics were established, and estimated risks were calculated for the mutations. RESULTS: No significant difference was observed in the genotype frequencies of the multidrug resistance 1 G2677T/A and C3435T polymorphisms between Crohn's disease and ulcerative colitis patients. In contrast, the C1236T polymorphism was significantly more common in Crohn's disease than in ulcerative colitis (p = 0.047. A significant association was also found between the multidrug resistance 1 C3435T polymorphism and the stricturing form of Crohn's disease (OR: 4.13; p = 0.009, whereas no association was found with penetrating behavior (OR: 0.33; p = 0.094. In Crohn's disease, a positive association was also found between the C3435T polymorphism and corticosteroid resistance/refractoriness (OR: 4.14; p = 0.010. However, no significant association was found between multidrug resistance 1 gene polymorphisms and UC subphenotypic categories. CONCLUSION: The multidrug resistance 1 gene polymorphism C3435T is associated with the stricturing phenotype and an inappropriate response to therapy in Crohn's disease. This association with Crohn's disease may support additional pathogenic roles for the multidrug resistance 1 gene in regulating gut

Incidence of antibiotics resistance among uropathogens in Omani children presenting with a single episode of urinary tract infection.

Science.gov (United States)

Sharef, Sharef W; El-Naggari, Mohamed; Al-Nabhani, Dana; Al Sawai, Ali; Al Muharrmi, Zakaria; Elnour, Ibtisam

2015-01-01

Urinary tract infection (UTI) is one of the most common community-acquired infections. Different organisms can be the cause of UTI in children, with resistance to antibiotics becoming a significant problem in the choice of treatment. Worldwide studies have documented the prevalence of uropathogens in different countries. However, there is no previous study documenting the incidence of different uropathogens in Oman. We aim to report the most common uropathogens and their antibiotic sensitivity patterns in children presenting with documented, single episode UTI at a tertiary hospital in Oman. A retrospective analysis of all Omani children below 14 years who presented with a case of first documented UTI to SQUH between September 2008 and August 2012 was conducted. Data were obtained from the patients' electronic records in the hospital information system. Data were then analyzed using SSPS (Statistical Package for Social Sciences program, Version 20, IBM, Chicago, IL, USA). In the retrospective review of all urine cultures, 438 positive urine cultures were identified. Out of those, 208 (47.5%) belonged to children with their first episode of UTI. Thirty-three patients were excluded and 75 patients were included in the final analysis. Escherichia coli was the most frequently encountered uropathogen in our cohort (69%), followed by Klebsiella pneumoniae infection (17%). Nearly half (46.6%) of these two common organism were resistant to Cotrimoxazole, while 31% of them were resistant to Augmentin. Twenty-four percent of the E. coli and K. pneumoniae strains were resistant to Cefuroxime, and only 10% were resistant to nitrofurantoin. Both Augmentin and Cotrimoxazole should not be the first line antibiotics to treat UTI. Copyright © 2015 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

Direct identification of antibiotic resistance genes on single plasmid molecules using CRISPR/Cas9 in combination with optical DNA mapping

Science.gov (United States)

Müller, Vilhelm; Rajer, Fredrika; Frykholm, Karolin; Nyberg, Lena K.; Quaderi, Saair; Fritzsche, Joachim; Kristiansson, Erik; Ambjörnsson, Tobias; Sandegren, Linus; Westerlund, Fredrik

2016-12-01

Bacterial plasmids are extensively involved in the rapid global spread of antibiotic resistance. We here present an assay, based on optical DNA mapping of single plasmids in nanofluidic channels, which provides detailed information about the plasmids present in a bacterial isolate. In a single experiment, we obtain the number of different plasmids in the sample, the size of each plasmid, an optical barcode that can be used to identify and trace the plasmid of interest and information about which plasmid that carries a specific resistance gene. Gene identification is done using CRISPR/Cas9 loaded with a guide-RNA (gRNA) complementary to the gene of interest that linearizes the circular plasmids at a specific location that is identified using the optical DNA maps. We demonstrate the principle on clinically relevant extended spectrum beta-lactamase (ESBL) producing isolates. We discuss how the gRNA sequence can be varied to obtain the desired information. The gRNA can either be very specific to identify a homogeneous group of genes or general to detect several groups of genes at the same time. Finally, we demonstrate an example where we use a combination of two gRNA sequences to identify carbapenemase-encoding genes in two previously not characterized clinical bacterial samples.

Ensemble Classifiers for Predicting HIV-1 Resistance from Three Rule-Based Genotypic Resistance Interpretation Systems.

Science.gov (United States)

Raposo, Letícia M; Nobre, Flavio F

2017-08-30

Resistance to antiretrovirals (ARVs) is a major problem faced by HIV-infected individuals. Different rule-based algorithms were developed to infer HIV-1 susceptibility to antiretrovirals from genotypic data. However, there is discordance between them, resulting in difficulties for clinical decisions about which treatment to use. Here, we developed ensemble classifiers integrating three interpretation algorithms: Agence Nationale de Recherche sur le SIDA (ANRS), Rega, and the genotypic resistance interpretation system from Stanford HIV Drug Resistance Database (HIVdb). Three approaches were applied to develop a classifier with a single resistance profile: stacked generalization, a simple plurality vote scheme and the selection of the interpretation system with the best performance. The strategies were compared with the Friedman's test and the performance of the classifiers was evaluated using the F-measure, sensitivity and specificity values. We found that the three strategies had similar performances for the selected antiretrovirals. For some cases, the stacking technique with naïve Bayes as the learning algorithm showed a statistically superior F-measure. This study demonstrates that ensemble classifiers can be an alternative tool for clinical decision-making since they provide a single resistance profile from the most commonly used resistance interpretation systems.

Conductometric Determination of Single Pores in Polyethyleneterephthalate Irradiated by Heavy Ions

CERN Document Server

Oganesyan, V R; Dörschel, B; Vetter, J E; Danziger, M; Hermsdorf, D

2002-01-01

Most of previous works devoted to the problem of track formation processes did not pay enough attention to direct measurement of the appearance of every individual pore in an array of many pores induced by the irradiation of polymer films with ions. Such measurements are not easy to carry out due to the extremely high electric resistance in the moment of pore opening. In this work the analysis of films irradiated with low particle fluences up to 3.7\\cdot 10^{3} ions/cm^2 is described. Polyethyleneterephthalate (PET) Hostaphan with a thickness of 20 m was used. The samples were irradiated with Bi ions of 11.4 MeV/amu energy. Using optimized etching conditions and computer aided data evaluation we obtained results, which are in good agreement with theoretical predictions and model calculations. The measured increase of conductivity beginning from the breakthrough of a single track up to the next pore opening in dependence on the etching time and the number of opened pores confirm the assumed model. Thus, the de...

Conductometric determination of single pores in polyethyleneterephthalate irradiated by heavy ions

CERN Document Server

Oganesyan, V R; Dörschel, B; Hermsdorf, D; Trofimov, V V; Vetter, J

2002-01-01

Most of the previous works devoted to the problem of track formation processes did not pay enough attention to direct measurement of the appearance of every individual pore in an array of many pores induced by the irradiation of polymer films with ions. Such measurements are not easy to carry out due to the extremely high electric resistance in the moment of pore opening. In this work the analysis of films irradiated with low particle fluences up to 3.7 centre dot 10 sup 3 ions/cm sup 2 is described. Polyethyleneterephthalate (PET) Hostaphan with a thickness of 20 mu m was used. The samples were irradiated with Bi ions of 11.4 MeV/amu energy. Using optimized etching conditions and computer aided data evaluation, we obtained results, which are in good agreement with theoretical predictions and model calculations. The measured increase of conductivity beginning from the breakthrough of a single track up to the next pore opening in dependence on the etching time and the number of opened pores confirm the assumed...

Minor drug-resistant HIV type-1 variants in breast milk and plasma of HIV type-1-infected Ugandan women after nevirapine single-dose prophylaxis.

Science.gov (United States)

Pilger, Daniel; Hauser, Andrea; Kuecherer, Claudia; Mugenyi, Kizito; Kabasinguzi, Rose; Somogyi, Sybille; Harms, Gundel; Kunz, Andrea

2011-01-01

Nevirapine single-dose (NVP-SD) reduces mother-to-child transmission of HIV type-1 (HIV-1), but frequently induces resistance mutations in the HIV-1 genome. Little is known about drug-resistant HIV-1 variants in the breast milk of women who have taken NVP-SD. Blood and breast milk samples of 39 HIV-1-infected Ugandan women were taken 6-12 weeks after NVP-SD intake. Samples were analysed by population sequencing and allele-specific real-time PCR (AS-PCR) with detection limits for NVP-resistant HIV-1 variants (K103N and Y181C) of D n = 5, G n = 2 and C n = 1). A total of 7 (37%) and 10 (53%) women carried NVP-resistant virus in breast milk and plasma, respectively. Overall, 71% (5/7) women with NVP-resistant HIV-1 in breast milk displayed >1 drug-resistant variant. Resistance in breast milk was higher at week 6 (6/13 samples [46%]) compared with week 12 (1/6 samples [17%]). In total, 10 drug-resistant populations harbouring the K103N and/or Y181C mutation were detected in the 19 breast milk samples; 7 (70%) were caused by resistant minorities (< 5% of the total HIV-1 population). In the four women with drug-resistant virus in both plasma and breast milk, the mutation patterns differed between the two compartments. Minor populations of drug-resistant HIV-1 were frequently found in breast milk of Ugandan women after exposure to NVP-SD. Further studies need to explore the role of minor drug-resistant variants in the postnatal transmission of (resistant) HIV-1.

Single Nucleotide Polymorphisms in B-Genome Specific UDP-Glucosyl Transferases Associated with Fusarium Head Blight Resistance and Reduced Deoxynivalenol Accumulation in Wheat Grain.

Science.gov (United States)

Sharma, Pallavi; Gangola, Manu P; Huang, Chen; Kutcher, H Randy; Ganeshan, Seedhabadee; Chibbar, Ravindra N

2018-01-01

An in vitro spike culture method was optimized to evaluate Fusarium head blight (FHB) resistance in wheat (Triticum aestivum) and used to screen a population of ethyl methane sulfonate treated spike culture-derived variants (SCDV). Of the 134 SCDV evaluated, the disease severity score of 47 of the variants was ≤30%. Single nucleotide polymorphisms (SNP) in the UDP-glucosyltransferase (UGT) genes, TaUGT-2B, TaUGT-3B, and TaUGT-EST, differed between AC Nanda (an FHB-susceptible wheat variety) and Sumai-3 (an FHB-resistant wheat cultivar). SNP at 450 and 1,558 bp from the translation initiation site in TaUGT-2B and TaUGT-3B, respectively were negatively correlated with FHB severity in the SCDV population, whereas the SNP in TaUGT-EST was not associated with FHB severity. Fusarium graminearum strain M7-07-1 induced early expression of TaUGT-2B and TaUGT-3B in FHB-resistant SCDV lines, which were associated with deoxynivalenol accumulation and reduced FHB disease progression. At 8 days after inoculation, deoxynivalenol concentration varied from 767 ppm in FHB-resistant variants to 2,576 ppm in FHB-susceptible variants. The FHB-resistant SCDV identified can be used as new sources of FHB resistance in wheat improvement programs.

Evaluation of the a.c. potential drop method to determine J-crack resistance curves for a pressure vessel steel

International Nuclear Information System (INIS)

Gibson, G.P.

1989-01-01

An evaluation has been carried out of the a.c. potential drop technique for determining J-crack growth resistance curves for a pressure vessel steel. The technique involves passing an alternating current through the specimen and relating the changes in the potential drop across the crack mouth to changes in crack length occuring during the test. The factors investigated were the current and voltage probe positions, the a.c. frequency and the test temperature. In addition, by altering the heat treatment of the material, J-crack resistance curves were obtained under both contained and non-contained yielding conditions. In all situations, accurate J-R curves could be determined. (author)

Left ventricular volume determination from single-photon emission computed tomography

International Nuclear Information System (INIS)

Bunker, S.R.; Hartshorne, M.F.; Schmidt, W.P.; Cawthon, M.A.; Karl, R.D. Jr.; Bauman, J.M.; Howard, W.H. III; Rubal, B.J.

1985-01-01

To compare the accuracy of single-photon emission computed tomography (SPECT) with that of contrast cineangiography in measuring left ventricular end-diastolic volume, 25 consecutive patients undergoing catheterizaiton for coronary artery or valvular heart disease were first evaluated scintigraphically. SPECT volume values showed a high degree of correlation with those determined by angiography with a standard error of the estimate of 23 ml. SPECT offers a highly accurate and essentially noninvasive method for measuring chamber volumes that is independent of geometric assumptions about ventricular configuration and chest wall attenuation and does not require blood sample counting

Left ventricular volume determination from single-photon emission computed tomography

Energy Technology Data Exchange (ETDEWEB)

Bunker, S.R.; Hartshorne, M.F.; Schmidt, W.P.; Cawthon, M.A.; Karl, R.D. Jr.; Bauman, J.M.; Howard, W.H. III; Rubal, B.J.

1985-02-01

To compare the accuracy of single-photon emission computed tomography (SPECT) with that of contrast cineangiography in measuring left ventricular end-diastolic volume, 25 consecutive patients undergoing catheterizaiton for coronary artery or valvular heart disease were first evaluated scintigraphically. SPECT volume values showed a high degree of correlation with those determined by angiography with a standard error of the estimate of 23 ml. SPECT offers a highly accurate and essentially noninvasive method for measuring chamber volumes that is independent of geometric assumptions about ventricular configuration and chest wall attenuation and does not require blood sample counting.

All-Ceramic Single Crown Restauration of Zirconia Oral Implants and Its Influence on Fracture Resistance: An Investigation in the Artificial Mouth

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Ralf-Joachim Kohal

2015-04-01

Full Text Available The aim of the current investigation was to evaluate the fracture resistance of one-piece zirconia oral implants with and without all-ceramic incisor crowns after long-term thermomechanical cycling. A total of 48 implants were evaluated. The groups with crowns (C, 24 samples and without crowns (N, 24 samples were subdivided according to the loading protocol, resulting in three groups of 8 samples each: Group “0” was not exposed to cyclic loading, whereas groups “5” and “10” were loaded with 5 and 10 million chewing cycles, respectively. This resulted in 6 different groups: C0/N0, C5/N5 and C10/N10. Subsequently, all 48 implants were statically loaded to fracture and bending moments were calculated. All implants survived the artificial aging. For the static loading the following average bending moments were calculated: C0: 326 Ncm; C5: 339 Ncm; C10: 369 Ncm; N0: 339 Ncm; N5: 398 Ncm and N10: 355 Ncm. To a certain extent, thermomechanical cycling resulted in an increase of fracture resistance which did not prove to be statistically significant. Regarding its fracture resistance, the evaluated ceramic implant system made of Y-TZP seems to be able to resist physiological chewing forces long-term. Restauration with all-ceramic single crowns showed no negative influence on fracture resistance.

Electromagnetic fields created by a beam in an axisymmetric infinitely thick single-layer resistive pipe: general formulas and low frequency approximations

CERN Document Server

Mounet, Nicolas Frank; CERN. Geneva. ATS Department

2015-01-01

This note provides general and approximate formulas for the electromagnetic fields created by a passing beam in an axisymmetric infinitely thick resistive pipe made of a single homogeneous layer. The full derivations and their resulting approximate expressions at low and intermediate frequencies are given here, as well as the conditions under which those approximations are valid. Beam-coupling impedances are also computed, and examples are shown.

Rapid emergence of ciprofloxacin-resistant enterobacteriaceae containing multiple gentamicin resistance-associated integrons in a Dutch hospital

NARCIS (Netherlands)

C. van der Schee (Cindy); N. Lemmens-den Toom (Nicole); M.C. Vos (Margreet); P.J. Lugtenburg (Pieternella); S. de Marie (Siem); H.A. Verbrugh (Henri); B. Löwenberg (Bob); W.H.F. Goessens (Wil); A.F. van Belkum (Alex); J.J. Cornelissen (Jan); H.P. Endtz (Hubert)

2001-01-01

textabstractIn a hematology unit in the Netherlands, the incidence of ciprofloxacin-resistant Enterobacter cloacae and Escherichia coli increased from from 1996 to 1999. Clonal spread of single genotypes of both ciprofloxacin-resistant E. coli and Enterobacter cloacae from

Microcontroller based Stator Winding Resistance Determination of Induction Motor Drive on Temperature Variations

OpenAIRE

Siraj Ahmed T; Sukhdeo Sao; K.S.R Anjaneyulu

2014-01-01

In this paper an experiment has been conducted to determine the online stator winding resistance of an induction motor, in industries as well as domestic purpose induction motors is largely utilized, as it has both applications of variable and constant torque operation nature. The major requirement of an electric drive system is its independent control of torque and speed; this is achieved in DC motor Drive but has more disadvantages. With the help of fast acting switching devices it is possi...

Determination of Antimicrobial Activity and Resistance to Oxidation of Moringa peregrina Seed Oil

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Ioanna Chinou

2012-02-01

Full Text Available The antimicrobial activity of the oil extracted with n-hexane from the seeds of Moringa peregrina was tested against Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa, Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Candida albicans, C. tropicalis and C. glabrata. The oil proved effective against all of the tested microorganisms. Standard antibiotics (netilmycin, 5-flucytocine, intraconazole and 7-amino-4-methylcoumarin-3-acetic acid were used for comparison. The resistance to oxidation of the extracted seed oil was also determined.

Real-Time Single-Frequency GPS/MEMS-IMU Attitude Determination of Lightweight UAVs

Science.gov (United States)

Eling, Christian; Klingbeil, Lasse; Kuhlmann, Heiner

2015-01-01

In this paper, a newly-developed direct georeferencing system for the guidance, navigation and control of lightweight unmanned aerial vehicles (UAVs), having a weight limit of 5 kg and a size limit of 1.5 m, and for UAV-based surveying and remote sensing applications is presented. The system is intended to provide highly accurate positions and attitudes (better than 5 cm and 0.5∘) in real time, using lightweight components. The main focus of this paper is on the attitude determination with the system. This attitude determination is based on an onboard single-frequency GPS baseline, MEMS (micro-electro-mechanical systems) inertial sensor readings, magnetic field observations and a 3D position measurement. All of this information is integrated in a sixteen-state error space Kalman filter. Special attention in the algorithm development is paid to the carrier phase ambiguity resolution of the single-frequency GPS baseline observations. We aim at a reliable and instantaneous ambiguity resolution, since the system is used in urban areas, where frequent losses of the GPS signal lock occur and the GPS measurement conditions are challenging. Flight tests and a comparison to a navigation-grade inertial navigation system illustrate the performance of the developed system in dynamic situations. Evaluations show that the accuracies of the system are 0.05∘ for the roll and the pitch angle and 0.2∘ for the yaw angle. The ambiguities of the single-frequency GPS baseline can be resolved instantaneously in more than 90% of the cases. PMID:26501281

Electrical capacity and resistance determination of emitting electric transducer

International Nuclear Information System (INIS)

Alba Fernandez, J.; Ramis Soriano, J.

2000-01-01

In this work we calculate the electrical resistance and capacity of emitting electric transducer, which is mainly formed, in direct relationship with its properties, by a ceramic capacitor. Our aim is to motivate the students with an attractive element in order to carry out traditional measurements of the charge and discharge transients of a capacitor, implementing high resistance setups. (Author) 5 refs

Phenotypic and molecular characterization of antimicrobial resistance in Proteus mirabilis isolates from dogs.

Science.gov (United States)

Harada, Kazuki; Niina, Ayaka; Shimizu, Takae; Mukai, Yujiro; Kuwajima, Ken; Miyamoto, Tadashi; Kataoka, Yasushi

2014-11-01

Large-scale monitoring of resistance to 14 antimicrobial agents was performed using 103 Proteus mirabilis strains isolated from dogs in Japan. Resistant strains were analysed to identify their resistance mechanisms. Rates of resistance to chloramphenicol, streptomycin, enrofloxacin, trimethoprim/sulfamethoxazole, kanamycin, ampicillin, ciprofloxacin, cephalothin, gentamicin, cefoxitin and cefotaxime were 20.4, 15.5, 12.6, 10.7, 9.7, 8.7, 5.8, 2.9, 2.9, 1.9 and 1.9%, respectively. No resistance to ceftazidime, aztreonam or imipenem was found. Class 1 and 2 integrases were detected in 2.9 and 11.7% of isolates, respectively. Class 1 integrons contained aadB or aadB-catB-like-blaOXA10-aadA1, whereas those of class 2 contained sat-aadA1, dhfr1-sat-aadA1 or none of the anticipated resistance genes. Of five distinct plasmid-mediated quinolone-resistance (PMQR) genes, only qnrD gene was detected in 1.9% of isolates. Quinolone-resistance determining regions (QRDRs) of gyrA and parC from 13 enrofloxacin-intermediate and -resistant isolates were sequenced. Seven strains had double mutations and three had single mutations. Three of nine ampicillin-resistant isolates harboured AmpC-type β-lactamases (i.e. blaCMY-2, blaCMY-4 and blaDHA-1). These results suggest that canine Proteus mirabilis deserves continued surveillance as an important reservoir of antimicrobial resistance determinants. This is the first report, to our knowledge, describing integrons, PMQRs and QRDR mutations in Proteus mirabilis isolates from companion animals. © 2014 The Authors.

Antimicrobial resistance and molecular characteristics of Streptococcus agalactiae isolated from women of reproductive age

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Magdalena Musiorska

2016-12-01

Full Text Available Introduction. Streptococcus agalactiae infections are among the most significant causes of neonatal invasive diseases. Proper screening and detection of pregnant women carrying GBS allows intrapartum administration of antibiotic prophylaxis and is an effective measure in preventing transmission of bacteria from mother to newborns. Material and methods. Sixty three bacterial strains were isolated from vaginal swabs from pregnant and nonpregnant women of reproductive age. Species were identified by colony morphology, haemolysis type, Gram staining and SLIDEX® Strepto Plus latex test. Antimicrobial resistance of 56 strains was determined using disk-diffusion method. The presence of molecular resistance determinants was assessed using PCR with specific primers, and capsular types were identified using multiplex PCR. Results. None of the strains were resistant to the first drug of choice, penicillin. A large percentage of isolates (78.6% were resistant to doxycycline. The prevalence of resistance to macrolides and lincosamides, antibiotics used in women allergic to penicillin, was high. Those results corresponded with PCR tests, as tetM and ermA1 were most frequently detected genes (98.4 and 87.3%, respectively. 7.94% of strains possessed 7 different out of 13 tested genes determining resistance to different groups of antimicrobials. Among the capsular types, Ia, which proved to be associated with the most severe and invasive infections in mothers and neonates, was the most prevalent (65.08%. Conclusions. Even though they are susceptible to penicillin, multidrug resistance is common among S. agalactiae strains isolated from women of reproductive age and this resistance can be caused by more than one gene per single isolate

Determination of the threshold-energy surface for copper using in-situ electrical-resistivity measurements in the high-voltage electron microscope

International Nuclear Information System (INIS)

King, W.E.; Merkle, K.L.; Meshii, M.

1981-01-01

A detailed study of the anisotropy of the threshold energy for Frenkel-pair production in copper was carried out experimentally, using in-situ electrical-resistivity measurements in the high-voltage electron microscope. These electrical-resistivity measurements, which are sensitive to small changes in point-defect concentration, were used to determine the damage or defect production rate. Damage-rate measurements in copper single crystals were carried out for approx.40 incident electron-beam directions and six electron energies from 0.4 to 1.1 MeV. The total cross section for Frenkel-pair production is proportional to the measured damage rate and can be theoretically calculated if the form of the threshold-energy surface is known. Trial threshold-energy surfaces were systematically altered until a ''best fit'' of the calculated to the measured total cross sections for Frenkel-pair production was obtained. The average threshold energy of this surface is 28.5 eV. The minimum threshold energy is 18 +- 2 eV and is located near . A ring of very high threshold energy (>50 eV) surrounds the direction. A damage function for single-defect production was derived from this surface and was applied to defect-production calculations at higher recoil energies. This function rises rather sharply from a value of zero at 17 eV to 0.8 at 42 eV. It has the value of 0.5 at 24.5 eV. Above 30 eV the slope of the curve begins to decrease, reflecting the presence of the high-energy regions of the threshold-energy surface. Both topographical and quantitative comparisons of the present surface with those in the literature were presented. Based on a chi 2 goodness-of-fit test, the present surface was found to predict the experimentally observed total cross sections for Frenkel-pair production significantly better than the other available surfaces. Also, the goodness of fit varied substantially less with energy and direction for the present surface

Identification of Tet 39, a novel class of tetracycline resistance determinant in Acinetobacter spp. of environmental and clinical origin

DEFF Research Database (Denmark)

Agersø, Yvonne; Guardabassi, L.

2005-01-01

A novel tetracycline resistance determinant named Tet 39 was found in unrelated Acinetobacter strains isolated from freshwater trout farms (n=4) and sewage (n=6) in Denmark, and from a clinical specimen in the Netherlands (n=1). The determinant was located on transferable plasmids and consisted o...

Molecular screening of antibiotic-resistant determinants among multidrug-resistant clinical isolates of Proteus mirabilis from SouthWest Nigeria.

Science.gov (United States)

Alabi, Olumuyiwa Samuel; Mendonça, Nuno; Adeleke, Olufemi Ezekiel; da Silva, Gabriela Jorge

2017-06-01

Globally, and particularly in developing countries, the menace of anti-microbial resistance is an accelerating problem. In Nigeria, increase in bacterial resistance has been phenotypically established but due to high cost, few molecular studies have been reported. This study screened for presence of transferable resistance genes and mobile genetic elements (MGEs) such as integron among multi-drug resistant (MDR) P. mirabilis . A total of 108 P. mirabilis strains collected from five tertiary hospitals in SouthWest Nigeria were subjected to antibiotic susceptibility study using disc-diffusion method. Transferable resistance genes and MGEs were amplified using Polymerase chain reaction (PCR) analysis and amplicons sequenced. Varied resistance was observed against all the antibiotics tested. About 56% of the isolates were MDR including those from 0-12 years old children. PCR analysis revealed the presence of aac(6')-Ib (33.3%), plasmid mediated quinolone resistance (PMQR) genes [qnrA (36.7%), acc(6')-Ib-cr (5%)], TEM (48.3%), CTX-M (6.7%) and integrons class 1 (58.3%) and class 2 (26.7%). Sequencing analysis revealed bla TEM-1 , bla CTX-M-15 associated with IS Ecp1 and eight different arrays of gene cassettes: aadA1, aadA1-qacH, aadB-aadA2, aadA5, dfrA7, dfrA15, dfrA17, dfrA17-aadA5 . Transferable resistance genes in association with MGEs are present in Nigerian P. mirabilis thus their potential in disseminating resistance.

Antibiotic resistance of lactic acid bacteria

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Bulajić Snežana

2008-01-01

Full Text Available Knowledge on the antibiotic resistance of lactic acid bacteria is still limited, possibly because of the large numbers of genera and species encountered in this group, as well as variances in their resistance spectra. The EFSA considers antibiotic resistances, especially transferable resistances, an important decision criterion for determining a strain's QPS status. There are no approved standards for the phenotypic or genotypic evaluation of antibiotic resistances in food isolates. Also, the choice of media is problematic, as well as the specification of MIC breakpoint values as a result of the large species variation and the possible resulting variation in MIC values between species and genera. The current investigations in this field showed that we might end up with a range of different species- or genus-specific breakpoint values that may further increase the current complexity. Another problem associated with safety determinations of starter strains is that once a resistance phenotype and an associated resistance determinant have been identified, it becomes difficult to show that this determinant is not transferable, especially if the resistance gene is not located on a plasmid and no standard protocols for showing genetic transfer are available. Encountering those problems, the QPS system should allow leeway for the interpretations of results, especially when these relate to the methodology for resistance phenotype determinations, determinations of MIC breakpoints for certain genera, species, or strains, the nondeterminability of a genetic basis of a resistance phenotype and the transferability of resistance genes.

Characterization and lytic activity of methicillin-resistant Staphylococcus aureus(MRSA phages isolated from NICU

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Golnar Rahimzadeh

2016-06-01

Full Text Available Background Methicillin-resistant Staphylococcus aureus (MRSA is a well-known pathogen that causes serious diseases in humans. As part of the efforts to control this pathogen, an isolated bacteriophage, Siphoviridae, which specifically targets Methicillin-resistant Staphylococcus aureus (MRSA, was characterized. Aims The objective of this study was to characterize of a virulent bacteriophage (Siphoviridae isolated from a NICU bathroom sink. Methods The MRSA strain was isolated from patient blood. The isolated strain was confirmed as MRSA using conventional methods. Phages were isolated from a NICU bathroom sink and activity was lytic as determined by spot test. Titer phage lysate was measured by the Double Layer Agar (DLA technique. The morphology was found with electron microscopy. The single-step growth curve was plotted. Results Electron microscopy showed the phage as a member of the family Siphoviridae, serogroup A and F. The isolated phage was capable of lytic activity against methicillin-resistant Staphylococcus aureus (MRSA strain as shown by spot test. By DLA, the titre of the phages was determined to be 10×108PFU/ml. The single-step growth curve showed that the latent period of the isolated bacteriophage was 30 min and the total number of viable progeny per infected host, burst size, was 2600 PFU/infected host. Conclusion In this study, two phages were isolated and characterized from a NICU bathroom sink, from the Siphoviridae family, which specifically targetsmethicillin-resistant Staphylococcus aureus (MRSA.

The effect of resistance exercise on the thermic effect of food.

Science.gov (United States)

Denzer, Charlene M; Young, John C

2003-09-01

The thermic effect of food (TEF) is the increment in energy expenditure above resting metabolic rate associated with the cost of absorption and processing of food for storage. Previous studies have shown that TEF is enhanced by aerobic endurance exercise of sufficient duration and intensity. The purpose of this study was to determine if a similar effect occurs with a single bout of resistance exercise (weightlifting). VO2 was measured in 9 healthy volunteers (3 males and 6 females) for 2 hours after ingestion of a 2760 kJ (660 kcal) carbohydrate meal with and without prior completion of a resistance training regimen (2 sets of 10 repetitions of 10 different exercises). The meal caused an immediate and persistent thermic effect in both the control and the exercise trial. Mean oxygen consumption over baseline increased 20% in the control trial and 34% in the exercise trial. TEF calculated from VO2 and RER (total area under the response curve above baseline) was 73% greater in the exercise trial compared with the control trial (159 +/- 18 vs. 92 +/- 14 KJ/2 hrs, p carbohydrate meal is enhanced following a single bout of resistance exercise.

In Vitro Activity of Ertapenem versus Ceftriaxone against Neisseria gonorrhoeae Isolates with Highly Diverse Ceftriaxone MIC Values and Effects of Ceftriaxone Resistance Determinants: Ertapenem for Treatment of Gonorrhea?

Science.gov (United States)

Golparian, Daniel; Limnios, Athena; Whiley, David; Ohnishi, Makoto; Lahra, Monica M.; Tapsall, John W.

2012-01-01

Clinical resistance to the currently recommended extended-spectrum cephalosporins (ESCs), the last remaining treatment options for gonorrhea, is being reported. Gonorrhea may become untreatable, and new treatment options are crucial. We investigated the in vitro activity of ertapenem, relative to ceftriaxone, against N. gonorrhoeae isolates and the effects of ESC resistance determinants on ertapenem. MICs were determined using agar dilution technique or Etest for international reference strains (n = 17) and clinical N. gonorrhoeae isolates (n = 257), which included the two extensively drug-resistant (XDR) strains H041 and F89 and additional isolates with high ESC MICs, clinical ESC resistance, and other types of clinical high-level and multidrug resistance (MDR). Genetic resistance determinants for ESCs (penA, mtrR, and penB) were sequenced. In general, the MICs of ertapenem (MIC50 = 0.032 μg/ml; MIC90 = 0.064 μg/ml) paralleled those of ceftriaxone (MIC50 = 0.032 μg/ml; MIC90 = 0.125 μg/ml). The ESC resistance determinants mainly increased the ertapenem MIC and ceftriaxone MIC at similar levels. However, the MIC ranges for ertapenem (0.002 to 0.125 μg/ml) and ceftriaxone (gonorrhea, particularly for the currently identified ESC-resistant cases and possibly in a dual antimicrobial therapy regimen. However, further knowledge regarding the genetic determinants (and their evolution) conferring resistance to both antimicrobials, and clear correlates between genetic and phenotypic laboratory parameters and clinical treatment outcomes, is essential. PMID:22547617

Pseudomonas aeruginosa cells adapted to benzalkonium chloride show resistance to other membrane-active agents but not to clinically relevant antibiotics.

Science.gov (United States)

Loughlin, M F; Jones, M V; Lambert, P A

2002-04-01

Our objective was to determine whether strains of Pseudomonas aeruginosa can adapt to growth in increasing concentrations of the disinfectant benzalkonium chloride (BKC), and whether co-resistance to clinically relevant antimicrobial agents occurs. Attempts were made to determine what phenotypic alterations accompanied resistance and whether these explained the mechanism of resistance. Strains were serially passaged in increasing concentrations of BKC in static nutrient broth cultures. Serotyping and genotyping were used to determine purity of the cultures. Two strains were examined for cross-resistance to other disinfectants and antibiotics by broth dilution MIC determination. Alterations in outer membrane proteins and lipopolysaccharide (LPS) expressed were examined by SDS-PAGE. Cell surface hydrophobicity and charge, uptake of disinfectant and proportion of specific fatty acid content of outer and cytoplasmic membranes were determined. Two P. aeruginosa strains showed a stable increase in resistance to BKC. Co-resistance to other quaternary ammonium compounds was observed in both strains; chloramphenicol and polymyxin B resistance were observed in one and a reduction in resistance to tobramycin observed in the other. However, no increased resistance to other biocides (chlorhexidine, triclosan, thymol) or antibiotics (ceftazidime, imipenem, ciprofloxacin, tobramycin) was detected. Characteristics accompanying resistance included alterations in outer membrane proteins, uptake of BKC, cell surface charge and hydrophobicity, and fatty acid content of the cytoplasmic membrane, although no evidence was found for alterations in LPS. Each of the two strains had different alterations in phenotype, indicating that such adaptation is unique to each strain of P. aeruginosa and does not result from a single mechanism shared by the whole species.

Annealing Effects on the Normal-State Resistive Properties of Underdoped Cuprates

Science.gov (United States)

Vovk, R. V.; Khadzhai, G. Ya.; Nazyrov, Z. F.; Kamchatnaya, S. N.; Feher, A.; Dobrovolskiy, O. V.

2018-05-01

The influence of room-temperature annealing on the parameters of the basal-plane electrical resistance of underdoped YBa_2Cu_3O_{7-δ } and HoBa_2Cu_3O_{7-δ } single crystals in the normal and superconducting states is investigated. The form of the derivatives dρ (T)/dT makes it possible to determine the onset temperature of the fluctuation conductivity and indicates a nonuniform distribution of the labile oxygen. Annealing has been revealed to lead to a monotonic decrease in the oxygen deficiency, that primarily manifests itself as a decrease in the residual resistance, an increase of T_c, and a decrease in the Debye temperature.

Crystal Structure of the Substrate-Binding Domain from Listeria monocytogenes Bile-Resistance Determinant BilE

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Stephanie J. Ruiz

2016-12-01

Full Text Available BilE has been reported as a bile resistance determinant that plays an important role in colonization of the gastrointestinal tract by Listeria monocytogenes, the causative agent of listeriosis. The mechanism(s by which BilE mediates bile resistance are unknown. BilE shares significant sequence similarity with ATP-binding cassette (ABC importers that contribute to virulence and stress responses by importing quaternary ammonium compounds that act as compatible solutes. Assays using related compounds have failed to demonstrate transport mediated by BilE. The putative substrate-binding domain (SBD of BilE was expressed in isolation and the crystal structure solved at 1.5 Å. Although the overall fold is characteristic of SBDs, the binding site varies considerably relative to the well-characterized homologs ProX from Archaeoglobus fulgidus and OpuBC and OpuCC from Bacillus subtilis. This suggests that BilE may bind an as-yet unknown ligand. Elucidation of the natural substrate of BilE could reveal a novel bile resistance mechanism.

On the combination of molecular replacement and single-wavelength anomalous diffraction phasing for automated structure determination

International Nuclear Information System (INIS)

Panjikar, Santosh; Parthasarathy, Venkataraman; Lamzin, Victor S.; Weiss, Manfred S.; Tucker, Paul A.

2009-01-01

The combination of molecular replacement and single-wavelength anomalous diffraction improves the performance of automated structure determination with Auto-Rickshaw. A combination of molecular replacement and single-wavelength anomalous diffraction phasing has been incorporated into the automated structure-determination platform Auto-Rickshaw. The complete MRSAD procedure includes molecular replacement, model refinement, experimental phasing, phase improvement and automated model building. The improvement over the standard SAD or MR approaches is illustrated by ten test cases taken from the JCSG diffraction data-set database. Poor MR or SAD phases with phase errors larger than 70° can be improved using the described procedure and a large fraction of the model can be determined in a purely automatic manner from X-ray data extending to better than 2.6 Å resolution

Cost-Effectiveness of Antibiotic Prophylaxis Strategies for Transrectal Prostate Biopsy in an Era of Increasing Antimicrobial Resistance.

Science.gov (United States)

Lee, Kyueun; Drekonja, Dimitri M; Enns, Eva A

2018-03-01

To determine the optimal antibiotic prophylaxis strategy for transrectal prostate biopsy (TRPB) as a function of the local antibiotic resistance profile. We developed a decision-analytic model to assess the cost-effectiveness of four antibiotic prophylaxis strategies: ciprofloxacin alone, ceftriaxone alone, ciprofloxacin and ceftriaxone in combination, and directed prophylaxis selection based on susceptibility testing. We used a payer's perspective and estimated the health care costs and quality-adjusted life-years (QALYs) associated with each strategy for a cohort of 66-year-old men undergoing TRPB. Costs and benefits were discounted at 3% annually. Base-case resistance prevalence was 29% to ciprofloxacin and 7% to ceftriaxone, reflecting susceptibility patterns observed at the Minneapolis Veterans Affairs Health Care System. Resistance levels were varied in sensitivity analysis. In the base case, single-agent prophylaxis strategies were dominated. Directed prophylaxis strategy was the optimal strategy at a willingness-to-pay threshold of $50,000/QALY gained. Relative to the directed prophylaxis strategy, the incremental cost-effectiveness ratio of the combination strategy was $123,333/QALY gained over the lifetime time horizon. In sensitivity analysis, single-agent prophylaxis strategies were preferred only at extreme levels of resistance. Directed or combination prophylaxis strategies were optimal for a wide range of resistance levels. Facilities using single-agent antibiotic prophylaxis strategies before TRPB should re-evaluate their strategies unless extremely low levels of antimicrobial resistance are documented. Copyright © 2018 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

The costs of infection and resistance as determinants of West Nile virus susceptibility in Culex mosquitoes

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Styer Linda M

2011-10-01

Full Text Available Abstract Background Understanding the phenotypic consequences of interactions between arthropod-borne viruses (arboviruses and their mosquito hosts has direct implications for predicting the evolution of these relationships and the potential for changes in epidemiological patterns. Although arboviruses are generally not highly pathogenic to mosquitoes, pathology has at times been noted. Here, in order to evaluate the potential costs of West Nile virus (WNV infection and resistance in a primary WNV vector, and to assess the extent to which virus-vector relationships are species-specific, we performed fitness studies with and without WNV exposure using a highly susceptible Culex pipiens mosquito colony. Specifically, we measured and compared survival, fecundity, and feeding rates in bloodfed mosquitoes that were (i infected following WNV exposure (susceptible, (ii uninfected following WNV exposure (resistant, or (iii unexposed. Results In contrast to our previous findings with a relatively resistant Cx. tarsalis colony, WNV infection did not alter fecundity or blood-feeding behaviour of Cx. pipiens, yet results do indicate that resistance to infection is associated with a fitness cost in terms of mosquito survival. Conclusions The identification of species-specific differences provides an evolutionary explanation for variability in vector susceptibility to arboviruses and suggests that understanding the costs of infection and resistance are important factors in determining the potential competence of vector populations for arboviruses.

Equivalent network for resistance and temperature coefficient of resistance versus temperature and composition of thick resistive films

International Nuclear Information System (INIS)

Kusy, A.

1987-01-01

Two types of elementary resistances in thick resistive films have been considered: (i) constriction resistance R/sub C/ determined by the bulk properties of conducting material and by the geometry of constriction, and (ii) barrier resistance R/sub B/ determined by the parameters of a thermally activated type of tunneling process and by the geometry of the metal-insulator-metal unit. On this basis a resistance network composed of a large number of the two types of resistances has been defined. The network has been considered as being equivalent to thick resistive film (TRF) from the point of view of the resistance and temperature coefficient of resistance (TCR). The parameters of this network have been evaluated by the computer-aided approximation of the experimental data found for RuO 2 -based TRFs. On the basis of the equations derived for the network as well as the results of the approximation process, it can be concluded that the small values of the network TCR result from the superposition of the TCR of the conducting component β/sub C/ and of the temperature coefficient of barrier resistance α/sub B/. In this superposition β/sub C/ is attenuated (by 1--2 orders of magnitude), while α/sub B/ is attenuated by only few percentages. The network has been found to be strongly barrier dominated

Diffraction and single-crystal elastic constants of Inconel 625 at room and elevated temperatures determined by neutron diffraction

International Nuclear Information System (INIS)

Wang, Zhuqing; Stoica, Alexandru D.; Ma, Dong; Beese, Allison M.

2016-01-01

In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.

Diffraction and single-crystal elastic constants of Inconel 625 at room and elevated temperatures determined by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhuqing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Stoica, Alexandru D. [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Ma, Dong, E-mail: dongma@ornl.gov [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Beese, Allison M., E-mail: amb961@psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

2016-09-30

In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.

On low-resistance neutral earthing mode in 20 kV overhead and cable networks

Directory of Open Access Journals (Sweden)

Mayorov Andrey

2017-01-01

Full Text Available The problems of justification and selection of the required single-phase short-circuit current values in cable and overhead networks of 20 kV with low-resistance neutral earthing are considered. It is shown that the desired values of the short-circuit current can be determined on the basis of harmonization of conflicting influencing factors: reliability of the relay protection and automation devices and required resistances of the earthing devices of electrical installations, including personnel safety. In this case, the main influencing factor is the electrical network structure and parameters

Prevalence of quinolone resistance determinant qnrA6 among broad- and extended-spectrum beta-lactam-resistant Proteus mirabilis and Morganella morganii clinical isolates with sul1-type class 1 integron association in a Tunisian Hospital.

Science.gov (United States)

Mahrouki, Sihem; Perilli, Mariagrazia; Bourouis, Amel; Chihi, Hela; Ferjani, Mustapha; Ben Moussa, Mohamed; Amicosante, Gianfranco; Belhadj, Omrane

2013-08-01

The aim of this study was to investigate the prevalence and the emergence of plasmid-mediated quinolone resistance among broad-spectrum beta-lactam-resistant Proteus mirabilis and Morganella morganii clinical isolates recovered in the Military Hospital in Tunisia. Of 200 strains examined, 50 exhibited resistance to quinolones. Quinolone resistance determinants (qnr and aac(6')-Ib-cr) were characterized by multiplex PCR and sequencing. Chromosomal quinolone resistance mutations in the quinolone resistance-determining region (QRDR) and class 1 integron characterization were analysed by PCR and sequencing. The clonal relationship between the isolates was studied by pulsed-field gel electrophoresis (PFGE). Fourteen isolates harboured qnrA6 and among them 8 (57%) were extended-spectrum beta-lactamase (ESBL) producers, whilst 12 (85%) isolates harboured blaDHA-1. Mutations in the QRDR were detected in gyrA (Ser83Ile, Glu87Lys), gyrB (Ser464Phe), and parC (Ser80Ile). qnrA6 and blaDHA-1 genes were found embedded in complex sul1-type class 1 integrons. A gene cassette carrying aac(6')-Ib-cr was found located in the class 1 integron upstream of the qacEΔ1 gene. According to the PFGE analysis, the isolates were clonally unrelated. This is the first description in North Africa of class 1 integrons carrying blaDHA-1, qnrA6 gene, and aac(6')-Ib-cr determinants in clinical strains of Proteus mirabilis and Morganella morganii.

Resistivity method contribution in determining of fault zone and hydro-geophysical characteristics of carbonate aquifer, eastern desert, Egypt

Science.gov (United States)

Ammar, A. I.; Kamal, K. A.

2018-03-01

Determination of fault zone and hydro-geophysical characteristics of the fractured aquifers are complicated, because their fractures are controlled by different factors. Therefore, 60 VESs were carried out as well as 17 productive wells for determining the locations of the fault zones and the characteristics of the carbonate aquifer at the eastern desert, Egypt. The general curve type of the recorded rock units was QKH. These curves were used in delineating the zones of faults according to the application of the new assumptions. The main aquifer was included at end of the K-curve type and front of the H-curve type. The subsurface layers classified into seven different geoelectric layers. The fractured shaly limestone and fractured limestone layers were the main aquifer and their resistivity changed from low to medium (11-93 Ω m). The hydro-geophysical properties of this aquifer such as the areas of very high, high, and intermediate fracture densities of high groundwater accumulations, salinity, shale content, porosity distribution, and recharging and flowing of groundwater were determined. The statistical analysis appeared that depending of aquifer resistivity on the water salinities (T.D.S.) and water resistivities add to the fracture density and shale content. The T.D.S. increasing were controlled by Na+, Cl-, Ca2+, Mg2+, and then (SO4)2-, respectively. The porosity was calculated and its average value was 19%. The hydrochemical analysis of groundwater appeared that its type was brackish and the arrangements of cation concentrations were Na+ > Ca2+ > Mg2+ > K+ and anion concentrations were Cl- > (SO4)2- > HCO3 - > CO3 -. The groundwater was characterized by sodium-bicarbonate and sodium-sulfate genetic water types and meteoric in origin. Hence, it can use the DC-resistivity method in delineating the fault zone and determining the hydro-geophysical characteristics of the fractured aquifer with taking into account the quality of measurements and interpretation.

Establishment of a nested-ASP-PCR method to determine the clarithromycin resistance of Helicobacter pylori.

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Luo, Xiao-Feng; Jiao, Jian-Hua; Zhang, Wen-Yue; Pu, Han-Ming; Qu, Bao-Jin; Yang, Bing-Ya; Hou, Min; Ji, Min-Jun

2016-07-07

To investigate clarithromycin resistance positions 2142, 2143 and 2144 of the 23SrRNA gene in Helicobacter pylori (H. pylori) by nested-allele specific primer-polymerase chain reaction (nested-ASP-PCR). The gastric tissue and saliva samples from 99 patients with positive results of the rapid urease test (RUT) were collected. The nested-ASP-PCR method was carried out with the external primers and inner allele-specific primers corresponding to the reference strain and clinical strains. Thirty gastric tissue and saliva samples were tested to determine the sensitivity of nested-ASP-PCR and ASP-PCR methods. Then, clarithromycin resistance was detected for 99 clinical samples by using different methods, including nested-ASP-PCR, bacterial culture and disk diffusion. The nested-ASP-PCR method was successfully established to test the resistance mutation points 2142, 2143 and 2144 of the 23SrRNA gene of H. pylori. Among 30 samples of gastric tissue and saliva, the H. pylori detection rate of nested-ASP-PCR was 90% and 83.33%, while the detection rate of ASP-PCR was just 63% and 56.67%. Especially in the saliva samples, nested-ASP-PCR showed much higher sensitivity in H. pylori detection and resistance mutation rates than ASP-PCR. In the 99 RUT-positive gastric tissue and saliva samples, the H. pylori-positive detection rate by nested-ASP-PCR was 87 (87.88%) and 67 (67.68%), in which there were 30 wild-type and 57 mutated strains in gastric tissue and 22 wild-type and 45 mutated strains in saliva. Genotype analysis showed that three-points mixed mutations were quite common, but different resistant strains were present in gastric mucosa and saliva. Compared to the high sensitivity shown by nested-ASP-PCR, the positive detection of bacterial culture with gastric tissue samples was 50 cases, in which only 26 drug-resistant strains were found through analyzing minimum inhibitory zone of clarithromycin. The nested-ASP-PCR assay showed higher detection sensitivity than ASP-PCR and

Relative work function of clean molybdenum single-crystal planes determined by field emission microscopy

International Nuclear Information System (INIS)

Bergeret, G.; Abon, M.; Tardy, B.; Teichner, S.J.

1974-01-01

A probe-hole field emission microscope was used to determine the work function of clean molybdenum single crystal planes relative to the average work function of the field emitter, assumed to be 4.20 eV. Results are compared with other available data

Overexpression of Aldo-Keto-Reductase in Azole-resistant Clinical Isolates of Candida Glabrata Determined by cDNA-AFLP

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Mansour Heidari

2013-01-01

Full Text Available Background: Candida glabrata causes significant medical problems in immunocompromised patients. Many strains of this yeast are intrinsically resistant to azole antifungal agents, and treatment is problematic, leading to high morbidity and mortality rates in immunosuppressed individuals. The primary goal of this study was to investigate the genes involved in the drug resistance of clinical isolates of C. glabrata.Methods: The clinical isolates of C. glabrata were collected in an epidemiological survey of candidal infection inimmunocompromised patients and consisted of four fluconazole and itraconazole resistant isolates, two fluconazoleand itraconazole sensitive isolates, and C. glabrata CBS 138 as reference strain. Antifungal susceptibility patterns ofthe organisms were determined beforehand by the Clinical and Laboratory Standards Institute (CLSI. The potentialgene(s implicated in antifungal resistance were investigated using complementary DNA- Amplified Fragment Length Polymorphism (cDNA-AFLP. Semi-quantitative RT-PCR was carried out to evaluate the expression of gene(s in resistant isolates as compared to sensitive and reference strains.Results and conclusions: The aldo-keto-reductase superfamily (AKR gene was upregulated in the resistant clinicalisolates as assessed by cDNA-AFLP. Semi-quantitative RT-PCR revealed AKR mRNA expression approximately twice that seen in the sensitive isolates. Overexpression of the AKR gene was associated with increased fluconazole and itraconazole resistance in C. glabrata. The data suggest that upregulation of the AKR gene might give a new insight into the mechanism of azole resistance.

Anomalous decrease of resistance at 250 K in ultrathin Au-Nb film on single-crystal silicon

International Nuclear Information System (INIS)

Yamamoto, H.; Kawashima, T.; Tanaka, M.

1986-01-01

Ultrathin Au-Nb films as thin as 0.2 about 10 nm were deposited on clean surfaces of single-crystal silicon in order to investigate interfacial excitonic superconductivity. The samples were classified into two types, Nb-Au/Si and Au-Nb-Au/Si. In the latter case, the secondary Au film was deposited on the former sample cooled by liquid nitrogen. In the Nb-Au/ Si type of sample, a sheet resistance, R /SUB s/ at room temperature abruptly increased from 10 3 Ωsq -1 order to about 10 5 Ωsq -1 in several days a few months after the sample preparation. Then the sample showed an anomalous decrease of R /SUB s/ at about 250 K and an approximately null resistance at lower temperatures. This phenomenon was not so stable and was observed only for a few days. The Au-Nb-Au/Si type of sample showed low R /SUB s/ (10 2 about 10 3 Ωsq -1 ) at room temperature. A decrease and disappearance of R /SUB s/ were also observed at about 240 K in the sample with comparatively good reproducibility. These phenomena are discussed qualitatively, based on the excitonic superconductive model for an interface of metal/semiconductor by Allender, Bray, and Bardeen

Association mapping of seed and disease resistance traits in Theobroma cacao L.

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Motilal, Lambert A; Zhang, Dapeng; Mischke, Sue; Meinhardt, Lyndel W; Boccara, Michel; Fouet, Olivier; Lanaud, Claire; Umaharan, Pathmanathan

2016-12-01

Microsatellite and single nucleotide polymorphism markers that could be used in marker assisted breeding of cacao were identified for number of filled seeds, black pod resistance and witches' broom disease resistance. An association mapping approach was employed to identify markers for seed number and resistance to black pod and witches' broom disease (WBD) in cacao (Theobroma cacao L.). Ninety-five microsatellites (SSRs) and 775 single nucleotide polymorphisms (SNPs) were assessed on 483 unique trees in the International Cocoa Genebank Trinidad (ICGT). Linkage disequilibrium (LD) and association mapping studies were conducted to identify markers to tag the phenotypic traits. Decay of LD occurred over an average 9.3 cM for chromosomes 1-9 and 2.5 cM for chromosome 10. Marker/trait associations were generally identified based on general linear models (GLMs) that incorporated principal components from molecular information on relatedness factor. Seven markers (mTcCIR 8, 66, 126, 212; TcSNP368, 697, 1370) on chromosomes 1 and 9 were identified for number of filled seeds (NSEED). A single marker was found for black pod resistance (mTcCIR280) on chromosome 3, whereas six markers on chromosomes 4, 5, 6, 8, and 10 were detected for WBD (mTcCIR91, 183; TcSNP375, 720, 1230 and 1374). It is expected that this association mapping study in cacao would contribute to the knowledge of the genetic determinism of cocoa traits and that the markers identified herein would prove useful in marker assisted breeding of cacao.

Single-locus complementary sex determination in the inbreeding wasp Euodynerus foraminatus Saussure (Hymenoptera: Vespidae).

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Stahlhut, J K; Cowan, D P

2004-03-01

The Hymenoptera have arrhenotokous haplodiploidy in which males normally develop from unfertilized eggs and are haploid, while females develop from fertilized eggs and are diploid. Multiple sex determination systems are known to underlie haplodiploidy, and the best understood is single-locus complementary sex determination (sl-CSD) in which sex is determined at a single polymorphic locus. Individuals heterozygous at the sex locus develop as females; individuals that are hemizygous (haploid) or homozygous (diploid) at the sex locus develop as males. sl-CSD can be detected with inbreeding experiments that produce diploid males in predictable proportions as well as sex ratio shifts due to diploid male production. This sex determination system is considered incompatible with inbreeding because the ensuing increase in homozygosity increases the production of diploid males that are inviable or infertile, imposing a high cost on matings between close relatives. However, in the solitary hunting wasp Euodynerus foraminatus, a species suspected of having sl-CSD, inbreeding may be common due to a high incidence of sibling matings at natal nests. In laboratory crosses with E. foraminatus, we find that sex ratios and diploid male production (detected as microsatellite heterozygosity) are consistent with sl-CSD, but not with other sex determination systems. This is the first documented example of sl-CSD in a hymenopteran with an apparent natural history of inbreeding, and thus presents a paradox for our understanding of hymenopteran genetics.

Prevalence of chlorhexidine-resistant methicillin-resistant Staphylococcus aureus following prolonged exposure.

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Schlett, Carey D; Millar, Eugene V; Crawford, Katrina B; Cui, Tianyuan; Lanier, Jeffrey B; Tribble, David R; Ellis, Michael W

2014-08-01

Chlorhexidine has been increasingly utilized in outpatient settings to control methicillin-resistant Staphylococcus aureus (MRSA) outbreaks and as a component of programs for MRSA decolonization and prevention of skin and soft-tissue infections (SSTIs). The objective of this study was to determine the prevalence of chlorhexidine resistance in clinical and colonizing MRSA isolates obtained in the context of a community-based cluster-randomized controlled trial for SSTI prevention, during which 10,030 soldiers were issued chlorhexidine for body washing. We obtained epidemiological data on study participants and performed molecular analysis of MRSA isolates, including PCR assays for determinants of chlorhexidine resistance and high-level mupirocin resistance and pulsed-field gel electrophoresis (PFGE). During the study period, May 2010 to January 2012, we identified 720 MRSA isolates, of which 615 (85.4%) were available for molecular analysis, i.e., 341 clinical and 274 colonizing isolates. Overall, only 10 (1.6%) of 615 isolates were chlorhexidine resistant, including three from the chlorhexidine group and seven from nonchlorhexidine groups (P > 0.99). Five (1.5%) of the 341 clinical isolates and five (1.8%) of the 274 colonizing isolates harbored chlorhexidine resistance genes, and four (40%) of the 10 possessed genetic determinants for mupirocin resistance. All chlorhexidine-resistant isolates were USA300. The overall prevalence of chlorhexidine resistance in MRSA isolates obtained from our study participants was low. We found no association between extended chlorhexidine use and the prevalence of chlorhexidine-resistant MRSA isolates; however, continued surveillance is warranted, as this agent continues to be utilized for infection control and prevention efforts. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Resistance to infection with Eimeria vermiformis in mouse radiation chimeras is determined by donor bone-marrow cells

International Nuclear Information System (INIS)

Joysey, H.S.; Wakelin, D.; Rose, M.E.

1988-01-01

The course of infection with Eimeria vermiformis was determined in BALB/b, BALB/c, and C57BL/10ScSn (B10) mice and in radiation chimeras prepared from the H-2-compatible BALB/b and B10 mice. The BALB strains, irrespective of H-2 haplotype, were resistant, the B10 mice were susceptible, and in the chimeras infection was characterized by the genotype of the donated bone-marrow cells and not by the phenotype of the recipient. Thus, the genetic control of relative resistance or susceptibility to infection with this parasite is expressed through bone-marrow-derived cells

Determination of the influence of dispersion pattern of pesticide-resistant individuals on the reliability of resistance estimates using different sampling plans.

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Shah, R; Worner, S P; Chapman, R B

2012-10-01

Pesticide resistance monitoring includes resistance detection and subsequent documentation/ measurement. Resistance detection would require at least one (≥1) resistant individual(s) to be present in a sample to initiate management strategies. Resistance documentation, on the other hand, would attempt to get an estimate of the entire population (≥90%) of the resistant individuals. A computer simulation model was used to compare the efficiency of simple random and systematic sampling plans to detect resistant individuals and to document their frequencies when the resistant individuals were randomly or patchily distributed. A patchy dispersion pattern of resistant individuals influenced the sampling efficiency of systematic sampling plans while the efficiency of random sampling was independent of such patchiness. When resistant individuals were randomly distributed, sample sizes required to detect at least one resistant individual (resistance detection) with a probability of 0.95 were 300 (1%) and 50 (10% and 20%); whereas, when resistant individuals were patchily distributed, using systematic sampling, sample sizes required for such detection were 6000 (1%), 600 (10%) and 300 (20%). Sample sizes of 900 and 400 would be required to detect ≥90% of resistant individuals (resistance documentation) with a probability of 0.95 when resistant individuals were randomly dispersed and present at a frequency of 10% and 20%, respectively; whereas, when resistant individuals were patchily distributed, using systematic sampling, a sample size of 3000 and 1500, respectively, was necessary. Small sample sizes either underestimated or overestimated the resistance frequency. A simple random sampling plan is, therefore, recommended for insecticide resistance detection and subsequent documentation.

Exploration of a new method in determining the glass transition temperature of BMGs by electrical resistivity

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Guo, Jing; Zu, Fangqiu; Chen, Zhihao; Zheng, Shubin; Yuan, Yuan

2005-07-01

Based on a brief retrospect of the method in establishing Tg of the bulk metallic glasses (BMGs), some perplexities concerning this are pointed out. With the experimental results of Zr-Al-Ni-Cu-X (Nb,Ti) BMGs, a electrical resistivity method is proposed to determine the glass transition temperature of BMGs. With the method, we define two kinds of characteristic temperature related to the glass transition, Tg-dep and Tg-int, respectively. By comparing Tg-dep and Tg-int with Tg determined by the DSC method, we have found that, for the same alloy at the same heating rate, Tg-dep is very close to Tg-onset while Tg-int is approximate to Tg-mid. As a method to determine the glass transition temperature, the electrical resistivity method has proved to be more convenient and practical in comparison with the DSC method, especially when the DSC curve cannot show the glass transition character of BMGs. In addition, we would emphasize that when we refer to Tg, it is necessary to expatiate on the way of denoting the glass transition temperature, such as Tg-dep or Tg-int ( Tg-onset or Tg-mid), and on the heating rate, in order to avoid ambiguity.

EXPERIMENTAL DETERMINATION OF LONGITUDINAL COMPONENT OF MAGNETIC FLUX IN FERROMAGNETIC WIRE OF SINGLE-CORE POWER CABLE ARMOUR

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I.A. Kostiukov

2014-12-01

Full Text Available A problem of determination of effective longitudinal magnetic permeability of single core power cable armour is defined. A technique for experimental determination of longitudinal component of magnetic flux in armour spiral ferromagnetic wire is proposed.

Determination of tungsten in high-alloy steels and heat resisting alloys by isotope dilution-spark source mass spectrometry

International Nuclear Information System (INIS)

Saito, Morimasa; Yamada, Kei; Okochi, Haruno; Hirose, Fumio

1983-01-01

Tungsten in high-alloy steels and heat-resisting alloys was determined by isotope dilution method combined with spark source mass spectrometry by using 183 W enriched tungsten. The spike solution was prepared by fusing tungsten trioxide in sodium carbonate. A high-alloy steel sample was dissolved in the mixture of sulfuric acid and phosphoric acid together with the spike solution; a sample of heat resisting alloy was similarly dissolved in the mixture of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid. The solution was evaporated to give dense white fumes. Tungsten was separated from the residue by a conventional cinchonine salt-precipitation method. The salt was ignited, and the residue was mixed with graphite powder and pressed into electrodes. The isotope 183 W and 184 W were measured. The method was applied to the determination of tungsten in JSS and NBS standard high-alloy steels and JAERI standard nickel- and NBS standard cobalt-base heat resisting alloys containing more than 0.05% tungsten. The results were obtained with satisfactory precision and accuracy. However, the results obtained for JSS standard high- speed steels containing molybdenum tended to be significantly lower than the certified values. (author)

Determination of nonlinear resistance voltage-current relationships by measuring harmonics

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Stafford, J. M.

1971-01-01

Test configuration measures harmonic signal amplitudes generated in nonlinear resistance. Vacuum-type voltmeter measures low frequency sinusoidal input signal amplitude and wave-analyzer measures amplitude of harmonic signals generated in junction. Input signal harmonics amplitude must not exceed that of harmonics generated in nonlinear resistance.

Multidrug Resistant Salmonella typhi in Asymptomatic Typhoid Carriers among Food Handlers in Namakkal District, Tamil Nadu

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Senthilkumar B

2005-01-01

Full Text Available Purpose: to screen Salmonella typhi in asymptomatic typhoid carriers and to find out drug resistance and ability of the strains to transmit drug resistance to other bacteria. Methods: Cultural characters, biochemical tests, antibiotic sensitivity test (disc diffusion, agarose gel electrophoresis, and conjugation protocols were done. Thirty five stool samples were collected from the suspected food handlers for the study. Results: Among 35 samples, (17.14% yielded a positive result. Out of these 4 (20.0% were women and 2 (13.33% were men. The isolates were tested with a number of conventional antibiotics viz, amikacin, amoxicillin, ampicillin, chloramphenicol, ciprofloxacin, co-trimaxazole, rifampicin, gentamicin, nalidixic acid, ofloxacin and tetracycline. Five isolates were having the multidrug resistant character. Four (66.66% multidrug resistant isolates were found to have plasmids, while one (16.66% multidrug resistant isolate had no plasmid and the chromosome encoded the resistance. Only one strain (16.66% showed single antibiotic resistance in the study and had no plasmid DNA. The molecular weights of the plasmids were determined and found to be 120 kb.The mechanism of spreading of drug resistance through conjugation process was analyzed. In the conjugation studies, the isolates having R+ factor showed the transfer of drug resistance through conjugation, which was determined by the development of antibiotic resistance in the recipients. Conclusion: This study shows that drug resistant strains are able to transfer genes encoding drug resistance.

Pt/Cu single-atom alloys as coke-resistant catalysts for efficient C-H activation

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Marcinkowski, Matthew D.; Darby, Matthew T.; Liu, Jilei; Wimble, Joshua M.; Lucci, Felicia R.; Lee, Sungsik; Michaelides, Angelos; Flytzani-Stephanopoulos, Maria; Stamatakis, Michail; Sykes, E. Charles H.

2018-03-01

The recent availability of shale gas has led to a renewed interest in C-H bond activation as the first step towards the synthesis of fuels and fine chemicals. Heterogeneous catalysts based on Ni and Pt can perform this chemistry, but deactivate easily due to coke formation. Cu-based catalysts are not practical due to high C-H activation barriers, but their weaker binding to adsorbates offers resilience to coking. Using Pt/Cu single-atom alloys (SAAs), we examine C-H activation in a number of systems including methyl groups, methane and butane using a combination of simulations, surface science and catalysis studies. We find that Pt/Cu SAAs activate C-H bonds more efficiently than Cu, are stable for days under realistic operating conditions, and avoid the problem of coking typically encountered with Pt. Pt/Cu SAAs therefore offer a new approach to coke-resistant C-H activation chemistry, with the added economic benefit that the precious metal is diluted at the atomic limit.

Pt/Cu single-atom alloys as coke-resistant catalysts for efficient C–H activation

Energy Technology Data Exchange (ETDEWEB)

Marcinkowski, Matthew D.; Darby, Matthew T.; Liu, Jilei; Wimble, Joshua M.; Lucci, Felicia R.; Lee, Sungsik; Michaelides, Angelos; Flytzani-Stephanopoulos, Maria; Stamatakis, Michail; Sykes, E. Charles H.

2018-01-08

The recent availability of shale gas has led to a renewed interest in C-H bond activation as the first step towards synthesis of fuels and fine chemicals. Heterogeneous catalysts based on Ni and Pt can perform this chemistry, but deactivate easily due to coke formation. Cu- based catalysts are not practical for this chemistry due to high C-H activation barriers, but their weaker binding to adsorbates offers resilience to coking. Utilizing Pt/Cu single atom alloys (SAAs) we examine C-H activation in a number of systems including methyl groups, methane, and butane using a combination of simulations, surface science, and catalysis studies. We find that Pt/Cu SAAs activate C-H bonds more efficiently than Cu, are stable for days under realistic operating conditions, and avoid the problem of coking typically encountered with Pt. Pt/Cu SAAs therefore offer a new approach to coke resistant C-H activation chemistry with the added economic benefit that the precious metal is diluted at the atomic limit.

Digital quantification of rolling circle amplified single DNA molecules in a resistive pulse sensing nanopore.

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Kühnemund, M; Nilsson, M

2015-05-15

Novel portable, sensitive and selective DNA sensor methods for bio-sensing applications are required that can rival conventionally used non-portable and expensive fluorescence-based sensors. In this paper, rolling circle amplification (RCA) products are detected in solution and on magnetic particles using a resistive pulse sensing (RPS) nanopore. Low amounts of DNA molecules are detected by padlock probes which are circularized in a strictly target dependent ligation reaction. The DNA-padlock probe-complex is captured on magnetic particles by sequence specific capture oligonucleotides and amplified by a short RCA. Subsequent RPS analysis is used to identify individual particles with single attached RCA products from blank particles. This proof of concept opens up for a novel non-fluorescent digital DNA quantification method that can have many applications in bio-sensing and diagnostic approaches. Copyright © 2014 Elsevier B.V. All rights reserved.

Barley yellow mosaic virus VPg is the determinant protein for breaking eIF4E-mediated recessive resistance in barley plants

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Huangai Li

2016-09-01

Full Text Available In this study, we investigated the barley yellow mosaic virus (BaYMV, genus Bymovirus factor(s responsible for breaking eIF4E-mediated recessive resistance genes (rym4/5/6 in barley. Genome mapping analysis using chimeric infectious cDNA clones between rym5-breaking (JT10 and rym5-non-breaking (JK05 isolates indicated that genome-linked viral protein (VPg is the determinant protein for breaking the rym5 resistance. Likewise, VPg is also responsible for overcoming the resistances of rym4 and rym6 alleles. Mutational analysis identified that amino acids Ser-118, Thr-120 and His-142 in JT10 VPg are the most critical residues for overcoming rym5 resistance in protoplasts. Moreover, the rym5-non-breaking JK05 could accumulate in the rym5 protoplasts when eIF4E derived from a susceptible barley cultivar was expressed from the viral genome. Thus, the compatibility between VPg and host eIF4E determines the ability of BaYMV to infect barley plants.

Molecular Detection of Antimicrobial Resistance

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Fluit, Ad C.; Visser, Maarten R.; Schmitz, Franz-Josef

2001-01-01

The determination of antimicrobial susceptibility of a clinical isolate, especially with increasing resistance, is often crucial for the optimal antimicrobial therapy of infected patients. Nucleic acid-based assays for the detection of resistance may offer advantages over phenotypic assays. Examples are the detection of the methicillin resistance-encoding mecA gene in staphylococci, rifampin resistance in Mycobacterium tuberculosis, and the spread of resistance determinants across the globe. However, molecular assays for the detection of resistance have a number of limitations. New resistance mechanisms may be missed, and in some cases the number of different genes makes generating an assay too costly to compete with phenotypic assays. In addition, proper quality control for molecular assays poses a problem for many laboratories, and this results in questionable results at best. The development of new molecular techniques, e.g., PCR using molecular beacons and DNA chips, expands the possibilities for monitoring resistance. Although molecular techniques for the detection of antimicrobial resistance clearly are winning a place in routine diagnostics, phenotypic assays are still the method of choice for most resistance determinations. In this review, we describe the applications of molecular techniques for the detection of antimicrobial resistance and the current state of the art. PMID:11585788

Development of a TaqMan Allelic Discrimination Assay for detection of Single Nucleotides Polymorphisms associated with anti-malarial drug resistance

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Kamau Edwin

2012-01-01

Full Text Available Abstract Background Anti-malarial drug resistance poses a threat to current global efforts towards control and elimination of malaria. Several methods are used in monitoring anti-malarial drug resistance. Molecular markers such as single nucleotide polymorphism (SNP for example are increasingly being used to identify genetic mutations related to anti-malarial drug resistance. Several methods are currently being used in analysis of SNP associated with anti-malarial drug resistance and although each one of these methods has unique strengths and shortcoming, there is still need to improve and/or develop new methods that will close the gap found in the current methods. Methods TaqMan Allelic Discrimination assays for detection of SNPs associated with anti-malarial drug resistance were designed for analysis on Applied Biosystems PCR platform. These assays were designed by submitting SNP sequences associated with anti-malarial drug resistance to Applied Biosystems website. Eleven SNPs associated with resistance to anti-malarial drugs were selected and tested. The performance of each SNP assay was tested by creating plasmid DNAs carrying codons of interests and analysing them for analysis. To test the sensitivity and specificity of each SNP assay, 12 clinical samples were sequenced at codons of interest and used in the analysis. Plasmid DNAs were used to establish the Limit of Detection (LoD for each assay. Results Data from genetic profiles of the Plasmodium falciparum laboratory strains and sequence data from 12 clinical samples was used as the reference method with which the performance of the SNP assays were compared to. The sensitivity and specificity of each SNP assay was establish at 100%. LoD for each assay was established at 2 GE, equivalent to less than 1 parasite/μL. SNP assays performed well in detecting mixed infection and analysis of clinical samples. Conclusion TaqMan Allelic Discrimination assay provides a good alternative tool in

Detection of mutations in mtrR gene in quinolone resistant strains of N.gonorrhoeae isolated from India

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S V Kulkarni

2015-01-01

Full Text Available Background and Objectives: Emergence of multi-drug resistant Neisseria gonorrhoeae resulting from new genetic mutation is a serious threat in controlling gonorrhea. This study was undertaken to identify and characterise mutations in the mtrR genes in N.gonorrhoeae isolates resistant to six different antibiotics in the quinolone group. Materials and Methods: The Minimum inhibitory concentrations (MIC of five quinolones for 64 N.gonorrhoeae isolates isolated during Jan 2007-Jun 2009 were determined by E-test method. Mutations in MtrR loci were examined by deoxyribonucleic acid (DNA sequencing. Results: The proportion of N.gonorrhoeae strains resistant to anti-microbials was 98.4% for norfloxacin and ofloxacin, 96.8% for enoxacin and ciprofloxacin, 95.3% for lomefloxacin. Thirty-one (48.4% strains showed mutation (single/multiple in mtrR gene. Ten different mutations were observed and Gly-45 → Asp, Tyr-105 → His being the most common observed mutation. Conclusion: This is the first report from India on quinolone resistance mutations in MtrRCDE efflux system in N.gonorrhoeae. In conclusion, the high level of resistance to quinolone and single or multiple mutations in mtrR gene could limit the drug choices for gonorrhoea.

Conductometric determination of single pores in polyethyleneterephthalate irradiated by heavy ions

International Nuclear Information System (INIS)

Oganesyan, V.R.; Trofimov, V.V.; Doerschel, B.; Hermsdorf, D.; Vetter, J.; Danziger, M.

2002-01-01

Most of the previous works devoted to the problem of track formation processes did not pay enough attention to direct measurement of the appearance of every individual pore in an array of many pores induced by the irradiation of polymer films with ions. Such measurements are not easy to carry out due to the extremely high electric resistance in the moment of pore opening. In this work the analysis of films irradiated with low particle fluences up to 3.7·10 3 ions/cm 2 is described. Polyethyleneterephthalate (PET) Hostaphan with a thickness of 20μm was used. The samples were irradiated with Bi ions of 11.4 MeV/amu energy. Using optimized etching conditions and computer aided data evaluation, we obtained results, which are in good agreement with theoretical predictions and model calculations. The measured increase of conductivity beginning from the breakthrough of a single track up to the next pore opening in dependence on the etching time and the number of opened pores confirm the assumed model. Thus, the developed 'track-by-track' method can be used effectively for description of the sequential appearance of individual pores in an electrolytic etching process

The equivalent circuit of single crab muscle fibers as determined by impedance measurements with intracellular electrodes.

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Eisenberg, R S

1967-07-01

The input impedance of muscle fibers of the crab was determined with microelectrodes over the frequency range 1 cps to 10 kc/sec. Care was taken to analyze, reduce, and correct for capacitive artifact. One dimensional cable theory was used to determine the properties of the equivalent circuit of the membrane admittance, and the errors introduced by the neglect of the three dimensional spread of current are discussed. In seven fibers the equivalent circuit of an element of the membrane admittance must contain a DC path and two capacitances, each in series with a resistance. In two fibers, the element of membrane admittance could be described by one capacitance in parallel with a resistance. In several fibers there was evidence for a third very large capacitance. The values of the elements of the equivalent circuit depend on which of several equivalent circuits is chosen. The circuit (with a minimum number of elements) that was considered most reasonably consistent with the anatomy of the fiber has two branches in parallel: one branch having a resistance R(e) in series with a capacitance C(e); the other branch having a resistance R(b) in series with a parallel combination of a resistance R(m) and a capacitance C(m). The average circuit values (seven fibers) for this model, treating the fiber as a cylinder of sarcolemma without infoldings or tubular invaginations, are R(e) = 21 ohm cm(2); C(e) = 47 microf/cm(2); R(b) = 10.2 ohm cm(2); R(m) = 173 ohm cm(2); C(m) = 9.0 microf/cm(2). The relation of this equivalent circuit and another with a nonminimum number of circuit elements to the fine structure of crab muscle is discussed. In the above equivalent circuit R(m) and C(m) are attributed to the sarcolemma; R(e) and C(e), to the sarcotubular system; and R(b), to the amorphous material found around crab fibers. Estimates of actual surface area of the sarcolemma and sarcotubular system permit the average circuit values to be expressed in terms of unit membrane area. The

Electrical resistivity tomography for early vadose leak detection under single shell storage tanks

International Nuclear Information System (INIS)

Narbutovshih, S.M.

1996-01-01

This document describes planned testing with Electrical Resistivity Tomography (ERT). It is prepared in support of TTP RL46WT51 Rev. 1, funded by the Tank Focus Area through the Office of Technology Integration. The primary goal of the testing for fiscal year 1996 (FY96) is to develop and demonstrate the ability to place vertical electrode arrays (VEA) with the cone penetrometer technology (CPT) to depths below existing single shell tanks (SST) at the DOE Hanford Site. It is desirable to have the capability to use CPT for this application for obvious reasons. First, current methods of emplacement, drilled boreholes, are expensive with respect to the rest of the ERT operation. Cone penetrometer VEA emplacements offer the opportunity to significantly reduce installation costs. Second, use of CPT will reduce emplacement time from weeks or months to just several days depending on the number of VEAs and the depth of placement. ERT is preferable to other monitoring methods since operation costs and turn around time are less than the current baselines of either groundwater sampling networks or borehole logging techniques. ERT cost savings can be substantial and will continue into the future. ERT can also provide complete coverage under a tank or other facility which is an important supplement to existing monitoring methods. Groundwater sampling provides one data point per well and borehole logging provides data along a line in the ground. Neither provide information from beneath a facility and thus, are not able to locate release points. These electrode arrays are used to acquire subsurface electrical resistance data in a manner appropriate for tomographic inversion. The resulting tomograms can then be used to detect, monitor and track contaminated moisture plumes leaking from underground storage tanks during waste retrieval operations

Genetic basis of resistance to trauma in inbred strains of mice

International Nuclear Information System (INIS)

Radojicic, C.; Andric, B.; Simovic, M.; Dujic, A.; Marinkovic, D.

1990-01-01

In this study the resistance to mechanical, thermal, and radiation trauma in four inbred strains of mice (AKR, BALB/c, CBA, and C57Bl/6) was compared with the degree of genetic resemblance, by analyzing the allozyme variabilities of these strains. It was shown that the highest degree of genetic resemblance was among CBA and AKR strains, which correlated with a similar degree of resistance to trauma. On the other hand, BALB/c and C57Bl/6 strains expressed significant differences, both genetically and with respect to the responses to trauma. The hypothesis is introduced that the genetic determination of the resistance to trauma is based on: (a) a polygenic control of general physiological homeostasis, with the possibility that (b) some specific genes or single loci may contribute more than others to such adaptations of the strains tested

Complete genome sequence of hypervirulent and outbreak-associated Acinetobacter baumannii strain LAC-4: epidemiology, resistance genetic determinants and potential virulence factors

Science.gov (United States)

Ou, Hong-Yu; Kuang, Shan N.; He, Xinyi; Molgora, Brenda M.; Ewing, Peter J.; Deng, Zixin; Osby, Melanie; Chen, Wangxue; Xu, H. Howard

2015-01-01

Acinetobacter baumannii is an important human pathogen due to its multi-drug resistance. In this study, the genome of an ST10 outbreak A. baumannii isolate LAC-4 was completely sequenced to better understand its epidemiology, antibiotic resistance genetic determinants and potential virulence factors. Compared with 20 other complete genomes of A. baumannii, LAC-4 genome harbors at least 12 copies of five distinct insertion sequences. It contains 12 and 14 copies of two novel IS elements, ISAba25 and ISAba26, respectively. Additionally, three novel composite transposons were identified: Tn6250, Tn6251 and Tn6252, two of which contain resistance genes. The antibiotic resistance genetic determinants on the LAC-4 genome correlate well with observed antimicrobial susceptibility patterns. Moreover, twelve genomic islands (GI) were identified in LAC-4 genome. Among them, the 33.4-kb GI12 contains a large number of genes which constitute the K (capsule) locus. LAC-4 harbors several unique putative virulence factor loci. Furthermore, LAC-4 and all 19 other outbreak isolates were found to harbor a heme oxygenase gene (hemO)-containing gene cluster. The sequencing of the first complete genome of an ST10 A. baumannii clinical strain should accelerate our understanding of the epidemiology, mechanisms of resistance and virulence of A. baumannii. PMID:25728466

Hydraulic resistance of biofilms

KAUST Repository

Dreszer, C.; Vrouwenvelder, Johannes S.; Paulitsch-Fuchs, Astrid H.; Zwijnenburg, Arie; Kruithof, Joop C.; Flemming, Hans Curt

2013-01-01

resistance is very low compared to the expected biofilm resistance and, thus, biofilm resistance can be determined accurately. Transmembrane pressure drop was monitored. As biofilm parameters, thickness, total cell number, TOC, and extracellular polymeric

[Resistance risk, cross-resistance and biochemical resistance mechanism of Laodelphax striatellus to buprofezin].

Science.gov (United States)

Mao, Xu-lian; Liu, Jin; Li, Xu-ke; Chi, Jia-jia; Liu, Yong-jie

2016-01-01

In order to investigate the resistance development law and biochemical resistance mechanism of Laodelphax striatellus to buprofezin, spraying rice seedlings was used to continuously screen resistant strains of L. striatellus and dipping rice seedlings was applied to determine the toxicity and cross-resistance of L. striatellus to insecticides. After 32-generation screening with buprofezin, L. striatellus developed 168.49 folds resistance and its reality heritability (h2) was 0.11. If the killing rate was 80%-90%, L. striatellus was expected to develop 10-fold resistance to buprofezin only after 5 to 6 generations breeding. Because the actual reality heritability of field populations was usually lower than that of the resistant strains, the production of field populations increasing with 10-fold resistance would need much longer time. The results of cross-resistance showed that resistant strain had high level cross-resistance with thiamethoxam and imidacloprid, low level cross-resistance with acetamiprid, and no cross-resistance with pymetrozine and chlorpyrifos. The activity of detoxification enzymes of different strains and the syergism of synergist were measured. The results showed that cytochrome P450 monooxygenase played a major role in the resistance of L. striatellus to buprofezin, the esterase played a minor role and the GSH-S-transferase had no effect. Therefore, L. striatellus would have high risk to develop resistance to buprofezin when used in the field and might be delayed by using pymetrozine and chlorpyrifos.

Issues in resistance, adherence, and comparative efficacy of the single-tablet regimen combination of tenofovir, emtricitabine, and efavirenz in the management of HIV-1 infection

Directory of Open Access Journals (Sweden)

Rebick G

2012-09-01

Full Text Available Gabriel Rebick, Sharon L WalmsleyDivision of Infectious Diseases, Department of Medicine, University Health Network, University of Toronto, Toronto, ON, CanadaAbstract: Atripla is the first once-daily, single-tablet, triple-combination antiretroviral therapy. It is recommended for the initial treatment of the naïve patient with human immunodeficiency virus-1 (HIV-1 infection in all current guidelines, based on its proven efficacy in numerous head-to-head randomized clinical trials. Not only has it proven efficacy, but the fixed-dose combination, Atripla, has resulted in an improvement in adherence, quality of life, and satisfaction among naïve as well as virally suppressed patients switching from another regimen. Despite the advantages, tolerability issues can arise that are related primarily to the efavirenz component, which is known to cause central nervous side effects such as dizziness, abnormal dreams, and anxiety. Although generally self-limited, these side-effects can lead to treatment discontinuation in the short- or long-term. Based on the observation of neural tube defects in macaque models, and isolated case reports in human fetuses with first trimester exposure, it is rated as Food and Drug Administration pregnancy category D, and considered as contraindicated in the first trimester of pregnancy where alternatives are available. Given the low genetic barrier of each of the individual components, resistance remains an important issue for patients with poor adherence, but is balanced in part by the long half-life of the drugs. Transmitted resistance is described in up to 16% of newly infected patients in population surveys, and is particularly prevalent in men who have sex with men. Minority variants that may impart resistant to efavirenz are not detected with currently used HIV-1 genotype assays, but nonetheless may also be implicated in patients who fail initial treatment. Several single-tablet regimens are recently licensed or in

Molecular Basis of Resistance to Selected Antimicrobial Agents in the Emerging Zoonotic Pathogen Streptococcus suis.

Science.gov (United States)

Gurung, Mamata; Tamang, Migma Dorji; Moon, Dong Chan; Kim, Su-Ran; Jeong, Jin-Ha; Jang, Geum-Chan; Jung, Suk-Chan; Park, Yong-Ho; Lim, Suk-Kyung

2015-07-01

Characterization of 227 Streptococcus suis strains isolated from pigs during 2010 to 2013 showed high levels of resistance to clindamycin (95.6%), tilmicosin (94.7%), tylosin (93.8%), oxytetracycline (89.4%), chlortetracycline (86.8%), tiamulin (72.7%), neomycin (70.0%), enrofloxacin (56.4%), penicillin (56.4%), ceftiofur (55.9%), and gentamicin (55.1%). Resistance to tetracyclines, macrolides, aminoglycosides, and fluoroquinolone was attributed to the tet gene, erm(B), erm(C), mph(C), and mef(A) and/or mef(E) genes, aph(3')-IIIa and aac(6')-Ie-aph(2″)-Ia genes, and single point mutations in the quinolone resistance-determining region of ParC and GyrA, respectively. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Development of elvitegravir resistance and linkage of integrase inhibitor mutations with protease and reverse transcriptase resistance mutations.

Directory of Open Access Journals (Sweden)

Mark A Winters

Full Text Available Failure of antiretroviral regimens containing elvitegravir (EVG and raltegravir (RAL can result in the appearance of integrase inhibitor (INI drug-resistance mutations (DRMs. While several INI DRMs have been identified, the evolution of EVG DRMs and the linkage of these DRMs with protease inhibitor (PI and reverse transcriptase inhibitor (RTI DRMs have not been studied at the clonal level. We examined the development of INI DRMs in 10 patients failing EVG-containing regimens over time, and the linkage of INI DRMs with PI and RTI DRMs in these patients plus 6 RAL-treated patients. A one-step RT-nested PCR protocol was used to generate a 2.7 kB amplicon that included the PR, RT, and IN coding region, and standard cloning and sequencing techniques were used to determine DRMs in 1,277 clones (mean 21 clones per time point. Results showed all patients had multiple PI, NRTI, and/or NNRTI DRMs at baseline, but no primary INI DRM. EVG-treated patients developed from 2 to 6 strains with different primary INI DRMs as early as 2 weeks after initiation of treatment, predominantly as single mutations. The prevalence of these strains fluctuated and new strains, and/or strains with new combinations of INI DRMs, developed over time. Final failure samples (weeks 14 to 48 typically showed a dominant strain with multiple mutations or N155H alone. Single N155H or multiple mutations were also observed in RAL-treated patients at virologic failure. All patient strains showed evidence of INI DRM co-located with single or multiple PI and/or RTI DRMs on the same viral strand. Our study shows that EVG treatment can select for a number of distinct INI-resistant strains whose prevalence fluctuates over time. Continued appearance of new INI DRMs after initial INI failure suggests a potent, highly dynamic selection of INI resistant strains that is unaffected by co-location with PI and RTI DRMs.

Determination of the resistance to tensile fracture of refractory mixtures of gunite

International Nuclear Information System (INIS)

Gomez Sanchez, A; Tomba Martinez, A.G

2004-01-01

The determination of the mechanical properties of cooled refractory mixtures is useful since it allows the materials to be compared for the purposes of selection and reports on their degree of internal cohesion, green or calcination, so that their structural ability can be estimated, especially during installation. Given the testing difficulties originating in the fragility of the ceramic materials, the tension test is not generally used in refractories. However, ASTM C-307 94 determines the tensile strength of cured chemical-resistant materials, for which this work considered the possibility of testing cement-based monolithic refractories in this non conventional condition. The tensile resistance to the fracture of three different refractory mixtures (A, B 1 and B 2 ), used in heat repairing by gunite in coking ovens, that were characterized by chemical, granulometric, and mineralogical analysis pycnometric density measurements. The pieces for the tests ('bone' type: length = 75 mm, maximum width = 40 mm, minimum width = 25 mm, thickness = 10 - 25 mm) were prepared by ramming of mixtures of material/water in a metallic mold; they were sinterized (1200 o C, 1h) and characterized by measures of bulk density, porosity and observation of the surface texture, in green and calcinated. The tensile tests, based on ASTM C-307 94, were performed in an Instron model 4467 machine in open air, at room temperature and position control (0.5 mm/min). The following values were obtained, in kPa: AW347±308; B 1 W738±130; B 2 W604±64. These values were lower than those for the tensile fracture module (MOR), although they displayed an equivalent order: A≤B 2 ≤B 1 . This was related to the characteristics of each refractory mixture and at the end of the pieces tested (CW)

Coarse Initial Orbit Determination for a Geostationary Satellite Using Single-Epoch GPS Measurements

Directory of Open Access Journals (Sweden)

Ghangho Kim

2015-04-01

Full Text Available A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO satellite using single-epoch measurements from a Global Positioning System (GPS receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite’s state, even when it is impossible to apply the classical single-point solutions (SPS. Through consideration of the characteristics of the GEO orbital elements and GPS measurements, the components of the state vector are reduced to three. However, the algorithm remains sufficiently accurate for a GEO satellite. The developed algorithm was tested on simulated measurements from two or three GPS satellites, and the calculated maximum position error was found to be less than approximately 40 km or even several kilometers within the geometric range, even when the classical SPS solution was unattainable. In addition, extended Kalman filter (EKF tests of a GEO satellite with the estimated initial state were performed to validate the algorithm. In the EKF, a reliable dynamic model was adapted to reduce the probability of divergence that can be caused by large errors in the initial state.

Coarse Initial Orbit Determination for a Geostationary Satellite Using Single-Epoch GPS Measurements

Science.gov (United States)

Kim, Ghangho; Kim, Chongwon; Kee, Changdon

2015-01-01

A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO) satellite using single-epoch measurements from a Global Positioning System (GPS) receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite’s state, even when it is impossible to apply the classical single-point solutions (SPS). Through consideration of the characteristics of the GEO orbital elements and GPS measurements, the components of the state vector are reduced to three. However, the algorithm remains sufficiently accurate for a GEO satellite. The developed algorithm was tested on simulated measurements from two or three GPS satellites, and the calculated maximum position error was found to be less than approximately 40 km or even several kilometers within the geometric range, even when the classical SPS solution was unattainable. In addition, extended Kalman filter (EKF) tests of a GEO satellite with the estimated initial state were performed to validate the algorithm. In the EKF, a reliable dynamic model was adapted to reduce the probability of divergence that can be caused by large errors in the initial state. PMID:25835299

Improved annotation of antibiotic resistance determinants reveals microbial resistomes cluster by ecology

OpenAIRE

Gibson, Molly K; Forsberg, Kevin J; Dantas, Gautam

2014-01-01

Antibiotic resistance is a dire clinical problem with important ecological dimensions. While antibiotic resistance in human pathogens continues to rise at alarming rates, the impact of environmental resistance on human health is still unclear. To investigate the relationship between human-associated and environmental resistomes, we analyzed functional metagenomic selections for resistance against 18 clinically relevant antibiotics from soil and human gut microbiota as well as a set of multidr...

Heat resistance of Escherichia coli O157:H7 in apple juice.

Science.gov (United States)

Splittstoesser, D F; McLellan, M R; Churey, J J

1996-03-01

The objective was to determine the effect of cider composition on the heat resistance of Escherichia coli O157:H7. The average D52 value in a model Empire apple juice was 18 min with a z value of 4.8 degrees C. Increasing the Brix from 11.8 to 16.5 degrees had no effect on thermal resistance, while increasing L-malic acid from 0.2 to 0.8%, or reducing the pH from 4.4 to 3.6 sensitized the cells to heat. The greatest effect on heat resistance was afforded by the preservatives benzoic and sorbic acids: D50 values in ciders containing 1,000 mg/l were 5.2 min in the presence of sorbic acid and only 0.64 min in the presence of benzoic acid. Commercial apple juice concentrates yielded lower numbers of survivors than single-strength juices even though their higher sugar concentrations of about 46 degrees Brix increased heat resistance.

Control over the resonance wavelength of fibre Bragg gratings using resistive coatings based on single-wall carbon nanotubes

Science.gov (United States)

Gladush, Yu. G.; Medvedkov, O. I.; Vasil'ev, S. A.; Kopylova, D. S.; Yakovlev, V. Ya.; Nasibulin, A. G.

2016-10-01

We demonstrate that a thin resistive coating based on single-wall carbon nanotubes applied to the lateral surface of an optical fibre allows it to be uniformly heated up to a temperature of ∼ 400 \\circ{\\text{C}} without damage to the coating. Using a fibre Bragg grating (FBG) as an example, we assess the efficiency of resonance wavelength thermal tuning and examine frequency characteristics that can be achieved using such coating. In particular, we show that the resonance wavelength of the FBG can be tuned over 3.2 {\\text{nm}} with an efficiency of 8.7 {\\text{nm}} {\\text{W}}-1 and time constant of ∼ 0.4 {\\text{s}}.

Two distinct classes of QTL determine rust resistance in sorghum.

Science.gov (United States)

Wang, Xuemin; Mace, Emma; Hunt, Colleen; Cruickshank, Alan; Henzell, Robert; Parkes, Heidi; Jordan, David

2014-12-31

Agriculture is facing enormous challenges to feed a growing population in the face of rapidly evolving pests and pathogens. The rusts, in particular, are a major pathogen of cereal crops with the potential to cause large reductions in yield. Improving stable disease resistance is an on-going major and challenging focus for many plant breeding programs, due to the rapidly evolving nature of the pathogen. Sorghum is a major summer cereal crop that is also a host for a rust pathogen Puccinia purpurea, which occurs in almost all sorghum growing areas of the world, causing direct and indirect yield losses in sorghum worldwide, however knowledge about its genetic control is still limited. In order to further investigate this issue, QTL and association mapping methods were implemented to study rust resistance in three bi-parental populations and an association mapping set of elite breeding lines in different environments. In total, 64 significant or highly significant QTL and 21 suggestive rust resistance QTL were identified representing 55 unique genomic regions. Comparisons across populations within the current study and with rust QTL identified previously in both sorghum and maize revealed a high degree of correspondence in QTL location. Negative phenotypic correlations were observed between rust, maturity and height, indicating a trend for both early maturing and shorter genotypes to be more susceptible to rust. The significant amount of QTL co-location across traits, in addition to the consistency in the direction of QTL allele effects, has provided evidence to support pleiotropic QTL action across rust, height, maturity and stay-green, supporting the role of carbon stress in susceptibility to rust. Classical rust resistance QTL regions that did not co-locate with height, maturity or stay-green QTL were found to be significantly enriched for the defence-related NBS-encoding gene family, in contrast to the lack of defence-related gene enrichment in multi-trait effect

Azole-Resistant Invasive Aspergillosis

DEFF Research Database (Denmark)

Stensvold, Christen Rune; Jørgensen, Lise Nistrup; Arendrup, Maiken Cavling

2012-01-01

with point mutation (s) in CYP51A (TR34/L98H and TR46/Y121F/T289A). In the third a single target enzyme alteration (G432S) is found. These resistant “environmental” strains have been detected in many West-European countries as well as in the Asia- Pacifics. Noticeably, these two continents account...... and classes available is impressive compared to the armamentarium in human medicine, azoles will remain the most important group in agriculture due to superior field performance and significant resistance in fungal pathogens to other compounds. Hence, further spread of environmental resistant Aspergillus...

Quantitative Evaluation of Cisplatin Uptake in Sensitive and Resistant Individual Cells by Single-Cell ICP-MS (SC-ICP-MS).

Science.gov (United States)

Corte Rodríguez, M; Álvarez-Fernández García, R; Blanco, E; Bettmer, J; Montes-Bayón, M

2017-11-07

One of the main limitations to the Pt-therapy in cancer is the development of associated drug resistance that can be associated with a significant reduction of the intracellular platinum concentration. Thus, intracellular Pt concentration could be considered as a biomarker of cisplatin resistance. In this work, an alternative method to address intracellular Pt concentration in individual cells is explored to permit the evaluation of different cell models and alternative therapies in a relatively fast way. For this aim, total Pt analysis in single cells has been implemented using a total consumption nebulizer coupled to inductively coupled plasma mass spectrometric detection (ICP-MS). The efficiency of the proposed device has been evaluated in combination with flow cytometry and turned out to be around 25% (cells entering the ICP-MS from the cells in suspension). Quantitative uptake studies of a nontoxic Tb-containing compound by individual cells were conducted and the results compared to those obtained by bulk analysis of the same cells. Both sets of data were statistically comparable. Thus, final application of the developed methodology to the comparative uptake of Pt-species in cisplatin resistant and sensitive cell lines (A2780cis and A2780) was conducted. The results obtained revealed the potential of this analytical strategy to differentiate between different cell lines of different sensitivity to the drug which might be of high medical interest.

Phenotypic- and Genotypic-Resistance Detection for Adaptive Resistance Management in Tetranychus urticae Koch.

Directory of Open Access Journals (Sweden)

Deok Ho Kwon

Full Text Available Rapid resistance detection is necessary for the adaptive management of acaricide-resistant populations of Tetranychus urticae. Detection of phenotypic and genotypic resistance was conducted by employing residual contact vial bioassay (RCV and quantitative sequencing (QS methods, respectively. RCV was useful for detecting the acaricide resistance levels of T. urticae, particularly for on-site resistance detection; however, it was only applicable for rapid-acting acaricides (12 out of 19 tested acaricides. QS was effective for determining the frequencies of resistance alleles on a population basis, which corresponded to 12 nonsynonymous point mutations associated with target-site resistance to five types of acaricides [organophosphates (monocrotophos, pirimiphos-methyl, dimethoate and chlorpyrifos, pyrethroids (fenpropathrin and bifenthrin, abamectin, bifenazate and etoxazole]. Most field-collected mites exhibited high levels of multiple resistance, as determined by RCV and QS data, suggesting the seriousness of their current acaricide resistance status in rose cultivation areas in Korea. The correlation analyses revealed moderate to high levels of positive relationships between the resistance allele frequencies and the actual resistance levels in only five of the acaricides evaluated, which limits the general application of allele frequency as a direct indicator for estimating actual resistance levels. Nevertheless, the resistance allele frequency data alone allowed for the evaluation of the genetic resistance potential and background of test mite populations. The combined use of RCV and QS provides basic information on resistance levels, which is essential for choosing appropriate acaricides for the management of resistant T. urticae.

The efficacy of early initiated, supervised, progressive resistance training compared to unsupervised, home-based exercise after unicompartmental knee arthroplasty: a single-blinded randomized controlled trial.

Science.gov (United States)

Jørgensen, Peter B; Bogh, Søren B; Kierkegaard, Signe; Sørensen, Henrik; Odgaard, Anders; Søballe, Kjeld; Mechlenburg, Inger

2017-01-01

To examine if supervised progressive resistance training was superior to home-based exercise in rehabilitation after unicompartmental knee arthroplasty. Single blinded, randomized clinical trial. Surgery, progressive resistance training and testing was carried out at Aarhus University Hospital and home-based exercise was carried out in the home of the patient. Fifty five patients were randomized to either progressive resistance training or home-based exercise. Patients were randomized to either progressive resistance training (home based exercise five days/week and progressive resistance training two days/week) or control group (home based exercise seven days/week). Preoperative assessment, 10-week (primary endpoint) and one-year follow-up were performed for leg extension power, spatiotemporal gait parameters and knee injury and osteoarthritis outcome score (KOOS). Forty patients (73%) completed 1-year follow-up. Patients in the progressive resistance training group participated in average 11 of 16 training sessions. Leg extension power increased from baseline to 10-week follow-up in progressive resistance training group (progressive resistance training: 0.28 W/kg, P= 0.01, control group: 0.01 W/kg, P=0.93) with no between-group difference. Walking speed and KOOS scores increased from baseline to 10-week follow-up in both groups with no between-group difference (six minutes walk test P=0.63, KOOS P>0.29). Progressive resistance training two days/week combined with home based exercise five days/week was not superior to home based exercise seven days/week in improving leg extension power of the operated leg.

Characterization of antibiotic resistance in Salmonella enterica isolates determined from ready-to-eat (RTE) salad vegetables.

Science.gov (United States)

Taban, Birce Mercanoglu; Aytac, Sait Aykut; Akkoc, Nefise; Akcelik, Mustafa

2013-01-01

In the last decade, ready-to-eat (RTE) salad vegetables are gaining increasing importance in human diet. However, since they are consumed fresh, inadequate washing during processing can bring on some foodborne illnesses, like salmonellosis, since these food items have natural contamination from soil and water. During 2009-2010, a total of 81 samples were purchased arbitrarily from local markets in Ankara, and were examined for Salmonella contamination. Salmonella screening was performed by using anti-Salmonella magnetic beads system and polymerase chain reaction (PCR) identification of the suspected colonies. Then, the antibiotic resistance profiles of four Salmonella strains identified (strains RTE-1, RTE-2, RTE-3, and RTE-4) were also investigated, since the mechanism by which Salmonella spp. have accumulated antibiotic resistance genes is of interest. All strains showed resistance against sulfonamides (MIC > 128 mg/L). Further results suggested that associated sulfonamide resistance genes were encoded by the 55.0 kb plasmid of strain RTE-1 that involves no integrons. As a result of using two primers (P1254 and P1283) in randomly amplified polymorphic DNA-PCR (RAPD-PCR) analysis, two common amplicons (364 bp and 1065 bp) were determined. The findings of this study provide support to the adoption of guidelines for the prudent use of antibiotics in order to reduce the number of pathogens present on vegetable and fruit farms. Besides, since it is shown that these bacteria started to gain resistance to antibiotics, it is necessary to further investigate the prevalence of them in foods.

Characterization of antibiotic resistance in Salmonella enterica isolates determined from ready-to-eat (RTE salad vegetables

Directory of Open Access Journals (Sweden)

Birce Mercanoglu Taban

2013-01-01

Full Text Available In the last decade, ready-to-eat (RTE salad vegetables are gaining increasing importance in human diet. However, since they are consumed fresh, inadequate washing during processing can bring on some foodborne illnesses, like salmonellosis, since these food items have natural contamination from soil and water. During 2009-2010, a total of 81 samples were purchased arbitrarily from local markets in Ankara, and were examined for Salmonella contamination. Salmonella screening was performed by using anti-Salmonella magnetic beads system and polymerase chain reaction (PCR identification of the suspected colonies. Then, the antibiotic resistance profiles of four Salmonella strains identified (strains RTE-1, RTE-2, RTE-3, and RTE-4 were also investigated, since the mechanism by which Salmonella spp. have accumulated antibiotic resistance genes is of interest. All strains showed resistance against sulfonamides (MIC > 128 mg/L. Further results suggested that associated sulfonamide resistance genes were encoded by the 55.0 kb plasmid of strain RTE-1 that involves no integrons. As a result of using two primers (P1254 and P1283 in randomly amplified polymorphic DNA-PCR (RAPD-PCR analysis, two common amplicons (364 bp and 1065 bp were determined. The findings of this study provide support to the adoption of guidelines for the prudent use of antibiotics in order to reduce the number of pathogens present on vegetable and fruit farms. Besides, since it is shown that these bacteria started to gain resistance to antibiotics, it is necessary to further investigate the prevalence of them in foods.

Single photon emission computed tomography imaging using 99Tcm-methoxyisobutylisonitrile predict the multi-drug resistance and chemotherapy efficacy of lung cancer

International Nuclear Information System (INIS)

Zhang Yiqiu; Shi Hongcheng

2008-01-01

Chemotherapy is one of the main comprehensive treatments for lung cancer, especially for non-small cell lung cancer (NSCIC) Multi-drug resistance of lung cancer plays an important role in the failure of chemotherapy. Early detection of multi-drug resistance (MDR) is essential for choosing a suitable chemotherapy regimen for the patients of lung cancer. In recent years lots of literature reports that MDR of lung cancer is related to many kinds of multi-drug resistance protein (MRP) expression in lung cancer. Some lipophilic chemotherapy drugs and 99 Tc m -methoxyisobutylisonitrile( 99 Tc m -MIBI)may be the same substrate for some MRP. These MRP can transport them out of the tumor cells, then the chemotherapy is invalid or non-radioactive concentration. The retention of 99 Tc m -MIBI in tumor cells is correlated with the expression of MRP, thus the prediction of the MRP expression before chemotherapy or monitoring MRP expression changes in the process of chemotherapy by using the noninvasive 99 Tc m -MIBI single photon emission computed tomography imaging is helpful to predict the MDR and chemotherapy efficacy of lung cancer. (authors)

Resistance and sheet resistance measurements using electron beam induced current

International Nuclear Information System (INIS)

Czerwinski, A.; Pluska, M.; Ratajczak, J.; Szerling, A.; KaPtcki, J.

2006-01-01

A method for measurement of spatially uniform or nonuniform resistance in layers and strips, based on electron beam induced current (EBIC) technique, is described. High electron beam currents are used so that the overall resistance of the measurement circuit affects the EBIC signal. During the evaluation, the electron beam is scanned along the measured object, whose load resistance varies with the distance. The variation is compensated by an adjustable resistance within an external circuit. The method has been experimentally deployed for sheet resistance determination of buried regions of lateral confinements in semiconductor laser heterostructures manufactured by molecular beam epitaxy

CCR5 Gene Disruption via Lentiviral Vectors Expressing Cas9 and Single Guided RNA Renders Cells Resistant to HIV-1 Infection

Science.gov (United States)

Liu, Jingjing; Zhang, Di; Kimata, Jason T.; Zhou, Paul

2014-01-01

CCR5, a coreceptor for HIV-1 entry, is a major target for drug and genetic intervention against HIV-1. Genetic intervention strategies have knocked down CCR5 expression levels by shRNA or disrupted the CCR5 gene using zinc finger nucleases (ZFN) or Transcription activator-like effector nuclease (TALEN). In the present study, we silenced CCR5 via CRISPR associated protein 9 (Cas9) and single guided RNAs (sgRNAs). We constructed lentiviral vectors expressing Cas9 and CCR5 sgRNAs. We show that a single round transduction of lentiviral vectors expressing Cas9 and CCR5 sgRNAs into HIV-1 susceptible human CD4+ cells yields high frequencies of CCR5 gene disruption. CCR5 gene-disrupted cells are not only resistant to R5-tropic HIV-1, including transmitted/founder (T/F) HIV-1 isolates, but also have selective advantage over CCR5 gene-undisrupted cells during R5-tropic HIV-1 infection. Importantly, using T7 endonuclease I assay we did not detect genome mutations at potential off-target sites that are highly homologous to these CCR5 sgRNAs in stably transduced cells even at 84 days post transduction. Thus we conclude that silencing of CCR5 via Cas9 and CCR5-specific sgRNAs could be a viable alternative strategy for engineering resistance against HIV-1. PMID:25541967

Tumour resistance to cisplatin: a modelling approach

Energy Technology Data Exchange (ETDEWEB)

Marcu, L [School of Chemistry and Physics, University of Adelaide, North Terrace, SA 5000 (Australia); Bezak, E [School of Chemistry and Physics, University of Adelaide, North Terrace, SA 5000 (Australia); Olver, I [Faculty of Medicine, University of Adelaide, North Terrace, SA 5000 (Australia); Doorn, T van [School of Chemistry and Physics, University of Adelaide, North Terrace, SA 5000 (Australia)

2005-01-07

Although chemotherapy has revolutionized the treatment of haematological tumours, in many common solid tumours the success has been limited. Some of the reasons for the limitations are: the timing of drug delivery, resistance to the drug, repopulation between cycles of chemotherapy and the lack of complete understanding of the pharmacokinetics and pharmacodynamics of a specific agent. Cisplatin is among the most effective cytotoxic agents used in head and neck cancer treatments. When modelling cisplatin as a single agent, the properties of cisplatin only have to be taken into account, reducing the number of assumptions that are considered in the generalized chemotherapy models. The aim of the present paper is to model the biological effect of cisplatin and to simulate the consequence of cisplatin resistance on tumour control. The 'treated' tumour is a squamous cell carcinoma of the head and neck, previously grown by computer-based Monte Carlo techniques. The model maintained the biological constitution of a tumour through the generation of stem cells, proliferating cells and non-proliferating cells. Cell kinetic parameters (mean cell cycle time, cell loss factor, thymidine labelling index) were also consistent with the literature. A sensitivity study on the contribution of various mechanisms leading to drug resistance is undertaken. To quantify the extent of drug resistance, the cisplatin resistance factor (CRF) is defined as the ratio between the number of surviving cells of the resistant population and the number of surviving cells of the sensitive population, determined after the same treatment time. It is shown that there is a supra-linear dependence of CRF on the percentage of cisplatin-DNA adducts formed, and a sigmoid-like dependence between CRF and the percentage of cells killed in resistant tumours. Drug resistance is shown to be a cumulative process which eventually can overcome tumour regression leading to treatment failure.

Tumour resistance to cisplatin: a modelling approach

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