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Sample records for susceptibility electrical resistivity

  1. Gamma-ray spectrometry, electrical resistivity, and magnetic susceptibility of agricultural soils in the Northwest region of the Parana State, Brazil; Gamaespectrometria, resistividade eletrica e susceptibilidade magnetica de solos agricolas no noroeste do estado do Parana

    Energy Technology Data Exchange (ETDEWEB)

    Becegato, Valter Antonio [Universidade do Estado de Santa Catarina-UDESC, Centro de Ciencias Agroveterinarias, Lages, SC (Brazil); Ferreira, Francisco Jose Fonseca, E-mail: becegato@cav.udesc.br, E-mail: francisco.ferreira@ufpr.br [Universidade Federal do Parana (LPGA/UFPR), Curitiba, PR (Brazil). Dept. de Geologia. Lab. de Pesquisas em Geofisica Aplicada

    2005-10-15

    Gamma-ray spectrometry, electrical resistivity, and magnetic susceptibility measurements were taken from agricultural areas near the City of Maringa, in the Northwest region of the Parana state, south Brazil, in order to characterize the spatial distribution of radionuclides (K, eU, and eTh), the apparent resistivity, and the magnetic susceptibility determined for soils. Three different types of soils are present in this agricultural area: Alfisoil, clayey texture Oxisoil, both deriving from Lower Cretaceous basalts of the Serra Geral Formation; and medium texture Oxisoil from reworked Serra Geral and Goio-Ere formations, the latter deriving from sandstones of the Upper Cretaceous Caiua Group. It could be observed that in more clayey soils both concentration of radionuclides and susceptibility values are higher than in more sandy soils, especially due to the higher adsorption in the former and to the higher availability of magnetic minerals in the latter. The average ppm and Bq Kg{sup -1} grades for K, eU, and eTh in the areas under anthropic activity are of 1766-54.75, 0.83-10.22, and 1.78-7.27, respectively. These grades are significantly higher than those of non-occupied or non-fertilized areas (1101-34.15 K, 0.14-1.69 eU, and 1.31-5.36 eTh in ppm and Bq Kg-1, respectively.) Correlations were observed between uranium and clay, uranium and magnetic susceptibility, uranium and organic matter, and between electric resistivity and clay grades. Varied concentrations of radionuclides were also observed in different fertilizer formulations applied to soy and wheat cultures. Apparent electric resistivity values between 25 and 647 Ohm.m and magnetic susceptibility values between 0.28 e 1.10 x 10-3 SI due to clay and magnetic minerals represented important soil discrimination factors in the study area that can be incorporated as easy, low-cost soil mapping tools. (author)

  2. Ethernet susceptibility to electric fast transients

    NARCIS (Netherlands)

    van Leersum, B.J.A.M.; Buesink, Frederik Johannes Karel; Bergsma, J.G.; Leferink, Frank Bernardus Johannes

    2013-01-01

    The effect of Electric Fast Transients (EFT) phenomena in an Ethernet interface set-up is investigated in order to get more insight in coupling and interference mechanisms, robustness and susceptibility levels of a typical Ethernet installation on board of a naval vessel. It is shown that already a

  3. The current susceptibility pattern of methicillin resistant ...

    African Journals Online (AJOL)

    The antimicrobial susceptibility pattern of methicillin-resistant Staphylococcus aureus (MRSA) from in-patients and out-patients at the University of Port Harcourt Teaching Hospital (UPTH) was studied. Fifty, S. aureus organisms were isolated from routine clinical specimens such as high vaginal, wound, urethral and ear ...

  4. The electricity sector susceptibility of European countries to climate change

    Science.gov (United States)

    Klein, Daniel R.; Olonscheck, Mady; Walther, Carsten; Kropp, Jürgen P.

    2014-05-01

    Due to the close relationship between electricity consumption, production and temperature, the electricity systems of countries are particularly susceptible to climate change. Based on a number of quantitative influencing factors, we provide a relative index for 21 European countries. This allows relevant stakeholders to identify the main influencing factors that determine the electricity system susceptibility of their country. The index was determined using 14 influencing factors that include those that increase or decrease susceptibility. This includes information on monthly mean temperature, electricity consumption, import, export and production by energy source for the period 2000-2011. Moreover, we consider the results of nine global climate models regarding future temperature changes as well as data on air conditioner prevalence by country. A quantitative relative ranked index describing the susceptibility of each country's electricity system is provided. In both Luxembourg and Greece, which top the list, the inability to meet electricity demand with inland production as well as a heavy reliance on combustible fuel electricity production explain part of the high relative susceptibility. Summer electricity consumption (another influencing factor) is expected to increase in Greece where current relatively warm temperatures, in the context of the countries included in this study, are expected to increase in the future. Comparatively, Norway was the least susceptible country based on our index. Norway is expected to benefit from rising projected temperatures, which will decrease winter electricity consumption and limit susceptibility. Furthermore, Norway's current electricity production exceeds consumption demand and is largely based on hydro, which also decreases susceptibility. The findings of this study enable policy makers, scientists and energy managers to examine the most important influencing factors that increase susceptibility and focus their adaptation

  5. Laboratory Measurement of the Electrical Resistivity of some ...

    African Journals Online (AJOL)

    ... readily susceptible to chemical weathering (e.g. quartzite) to have high resistivities; conversely, gneisses which are more easily weathered, are characterized by relatively low electrical resistivities. (Af. J. of Science and Technology: 2002 3(1): 93-97). http://dx.doi.org/10.4314/ajst.v3i1.15291 · AJOL African Journals Online.

  6. Are there stress resistant and susceptible myocardia?

    Science.gov (United States)

    Knight, V A

    1988-11-01

    The satisfactory analysis of the Na/K ATPase, its pumping component and the mechanism of action of the inhibitor digitalis remains elusive; yet the controversial inotropic effect of digitalis in the clinical setting has been known for over a century. There are also conflicting reports of the effect of urea and uremia on the cardiovascular system, and the evidence as it exists, suggests that urea may have two effects on the intact heart, by virtue of its extent of action on hydrogen bonding of water molecules, determined by which type of muscle constitutes the myocardium. If different types of myocardium do exist, they could well respond differently to inotropic agents. Evidence suggests that two types of myocardia, relatively stress resistant or susceptible may exist, analagous to known skeletal muscle differences.

  7. ENU Mutagenic Screen for Susceptibility and Resistance to Streptococcus Pneumoniae

    National Research Council Canada - National Science Library

    Kindy, Mark S

    2005-01-01

    .... The genetic pathways that control susceptibility and resistance to bacterial infection have remained poorly understood, because of the lack of expertise in the development of techniques capable...

  8. Orientational Glasses: NMR and Electric Susceptibility Studies

    Directory of Open Access Journals (Sweden)

    Neil Sullivan

    2017-11-01

    Full Text Available We review the results of a wide range of nuclear magnetic resonance (NMRmeasurements of the local order parameters and the molecular dynamics of solid ortho-para hydrogen mixtures and solid nitrogen-argon mixtures that form novel molecular orientational glass states at low temperatures. From the NMR measurements, the distribution of the order parameters can be deduced and, in terms of simple models, used to analyze the thermodynamic measurements of the heat capacities of these systems. In addition, studies of the dielectric susceptibilities of the nitrogen-argon mixtures are reviewed in terms of replica symmetry breaking analogous to that observed for spin glass states. It is shown that this wide set of experimental results is consistent with orientation or quadrupolar glass ordering of the orientational degrees of freedom.

  9. Determining the specific electric resistance of rock

    Energy Technology Data Exchange (ETDEWEB)

    Persad' ko, V.Ia.

    1982-01-01

    Data are presented on perfecting the method of laboratory determination of the specific electric resistance of a rock formation. The average error in determining the specific electric resistance of the core at various locations is no more than two percent with low resistance values (2-5 ohms).

  10. The screening of multi-drug resistance (MDR) susceptibilities of ...

    African Journals Online (AJOL)

    The screening of multi-drug resistance (MDR) susceptibilities of Staphylococcus aureus and Staphylococcus epidermidis to methicillin and vancomycin in teaching ... β-lactam antibiotics that predispose patients to acquisition of methicillin -resistant Staph. aureus (MRSA) and coagulase negative resistant staphylococci.

  11. Susceptibility-resistance profile of micro-organisms isolated from ...

    African Journals Online (AJOL)

    SERVER

    2007-12-17

    Dec 17, 2007 ... microbial isolates in the HMPs could lead to transfer of antibiotic resistance traits to hitherto sensitive gut or oral microflora of consumers. The present study attempts to evaluate the potential health hazards associated with the consumption of herbal medicinal products vis-a-vis the susceptibility-resistance.

  12. Molecular genotyping of methicillin resistant and susceptible ...

    African Journals Online (AJOL)

    Background: Methicillin-resistant Staphylococcus aureus (MRSA) which causes nosocomial infections is among the most important multi-resistant pathogens worldwide. Investigations of MRSA outbreaks in nosocomial settings often require strain-typing data to verify effectively that the isolates belong to the outbreak strain, ...

  13. tration on Phenotypic Antibiotic Susceptibility and Resistance

    African Journals Online (AJOL)

    The crisis of antimicrobial drug resistance in human medi- cine has brought into question every aspect of ... however, the effect of antimicrobial drug use in companion animals like dogs or the acquisition of resistant bacteria by ... body weight ranging from 11-15kg were used in this study. The experimen- tal animals, clinical ...

  14. Electrical resistivity measurements to predict abrasion resistance of ...

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. The prediction of Los Angeles (LA) abrasion loss from some indirect tests is useful for practical applications. For this purpose, LA abrasion, electrical resistivity, density and porosity tests were carried out on 27 different rock types. LA abrasion loss values were correlated with electrical resistivity and a good corre-.

  15. Electrical resistivity measurements to predict abrasion resistance of ...

    Indian Academy of Sciences (India)

    The prediction of Los Angeles (LA) abrasion loss from some indirect tests is useful for practical applications. For this purpose, LA abrasion, electrical resistivity, density and porosity tests were carried out on 27 different rock types. LA abrasion loss values were correlated with electrical resistivity and a good correlation ...

  16. Dynamic magnetic susceptibility and electrical detection of ferromagnetic resonance

    Science.gov (United States)

    Zhang, Yin; Wang, X. S.; Yuan, H. Y.; Kang, S. S.; Zhang, H. W.; Wang, X. R.

    2017-03-01

    The dynamic magnetic susceptibility of magnetic materials near ferromagnetic resonance (FMR) is very important in interpreting the dc voltage obtained in its electrical detection. Based on the causality principle and the assumption that the usual microwave absorption lineshape of a homogeneous magnetic material around FMR is Lorentzian, the general forms of the dynamic magnetic susceptibility of an arbitrary sample and the corresponding dc voltage lineshapes of its electrical detection were obtained. Our main findings are as follows. (1) The dynamic magnetic susceptibility is not a Polder tensor for a material with an arbitrary magnetic anisotropy. The two off-diagonal matrix elements of the tensor near FMR are not, in general, opposite to each other. However, the linear response coefficient of the magnetization to the total radio frequency (rf) field (the sum of the external and internal rf fields due to precessing magnetization is a quantity which cannot be measured directly) is a Polder tensor. This may explain why the two off-diagonal susceptibility matrix elements were always wrongly assumed to be opposite to each other in almost all analyses. (2) The frequency dependence of dynamic magnetic susceptibility near FMR is fully characterized by six real numbers, while its field dependence is fully characterized by seven real numbers. (3) A recipe of how to determine these numbers by standard microwave absorption measurements for a sample with an arbitrary magnetic anisotropy is proposed. Our results allow one to unambiguously separate the contribution of the anisotropic magnetoresistance to the dc voltage signals from the anomalous Hall effect. With these results, one can reliably extract the information of spin pumping and the inverse spin-Hall effect, and determine the spin-Hall angle. (4) In the case that resonance frequency is not sensitive to the applied static magnetic field, the field dependence of the matrix elements of dynamic magnetic susceptibility, as

  17. 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

    . 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...... these figures were 67% and 42%, respectively, for the reference strains.Genotyping of tetracycline resistance determinants was performed with primers specific for tet(A–E, H, K–M, O). Strains positive for tet(B), tet(H) and tet(L) were identified, however, in 20 out of 49 tetracycline resistant strains...... 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...

  18. Electrical resistivity measurement to predict uniaxial compressive ...

    Indian Academy of Sciences (India)

    Electrical resistivity values of 12 different igneous rocks were measured on core samples using a resistivity meter in the laboratory. The resistivity tests were conducted on the samples fully saturated with brine (NaCl solution) and the uniaxial compressive strength (UCS), Brazilian tensile strength, density and porosity values ...

  19. Electrical resistivity measurement to predict uniaxial compressive ...

    Indian Academy of Sciences (India)

    Abstract. Electrical resistivity values of 12 different igneous rocks were measured on core samples using a resistivity meter in the laboratory. The resistivity tests were conducted on the samples fully saturated with brine (NaCl solution) and the uniaxial compressive strength (UCS), Brazilian tensile strength, density and.

  20. Coke fouling monitoring by electrical resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Bombardelli, Clovis; Mari, Livia Assis; Kalinowski, Hypolito Jose [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-Graduacao em Engenharia Eletrica e Informatica Industrial (CPGEI)

    2008-07-01

    An experimental method to simulate the growth of the coke fouling that occurs in the oil processing is proposed relating the thickness of the encrusted coke to its electrical resistivity. The authors suggest the use of the fouling electrical resistivity as a transducer element for determining its thickness. The sensor is basically two electrodes in an electrically isolated device where the inlay can happen in order to compose a purely resistive transducer. Such devices can be easily constructed in a simple and robust form with features capable to face the high temperatures and pressures found in relevant industrial processes. For validation, however, it is needed a relationship between the electrical resistivity and the fouling thickness, information not yet found in the literature. The present work experimentally simulates the growth of a layer of coke on an electrically insulating surface, equipped with electrodes at two extremities to measure the electrical resistivity during thermal cracking essays. The method is realized with a series of consecutive runs. The results correlate the mass of coke deposited and its electrical resistivity, and it can be used to validate the coke depositions monitoring employing the resistivity as a control parameter. (author)

  1. Is Streptococcus pyogenes Resistant or Susceptible to Trimethoprim-Sulfamethoxazole?

    OpenAIRE

    Bowen, Asha C.; Lilliebridge, Rachael A; Tong, Steven Y. C.; Baird, Robert W.; Ward, Peter; McDonald, Malcolm I.; Currie, Bart J.; Jonathan R Carapetis

    2012-01-01

    Streptococcus pyogenes is commonly believed to be resistant to trimethoprim-sulfamethoxazole (SXT), resulting in reservations about using SXT for skin and soft tissue infections (SSTI) where S. pyogenes is involved. S. pyogenes' in vitro susceptibility to SXT depends on the medium's thymidine content. Thymidine allows S. pyogenes to bypass the sulfur-mediated inhibition of folate metabolism and, historically, has resulted in apparently reduced susceptibility of S. pyogenes to sulfur antibacte...

  2. antibiotic susceptibility pattern and multiple antibiotic resistance

    African Journals Online (AJOL)

    pg, gentamicin 10 pg, streptomycin 30 pg, erythromycin 30 ug and chloramphenicol 20 tlg. Pseudomonas aeruginosa NCTC 10662 served as control. Determination of MAR index. The MAR index was determined for each isolate by dividing the number of antibiotics to which the isolate is resistant by the total number of ...

  3. Estimating soil suction from electrical resistivity

    OpenAIRE

    Piegari, E.; R. Maio

    2013-01-01

    Soil suction and resistivity strongly depend on the degree of soil saturation and, therefore, both are used for estimating water content variations. The main difference between them is that soil suction is measured using tensiometers, which give point information, while resistivity is obtained by tomography surveys, which provide distributions of resistivity values in large volumes, although with less accuracy. In this paper, we have related soil suction to electrical resistivity with the aim...

  4. A new empirical complex electrical resistivity model

    NARCIS (Netherlands)

    Kavian, M.; Slob, E.C.; Mulder, W.A.

    2012-01-01

    Macroscopic measurements of electrical resistivity require frequency-dependent effective models that honor the microscopic effects observable in macroscopic measurements. Effective models based on microscopic physics exist alongside with empirical models. We adopted an empirical model approach to

  5. 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, southwestern Nigeria. A I Idornigie, M O Olorunfemi, A A Omitogun ...

  6. Is Streptococcus pyogenes Resistant or Susceptible to Trimethoprim-Sulfamethoxazole?

    Science.gov (United States)

    Lilliebridge, Rachael A.; Tong, Steven Y. C.; Baird, Robert W.; Ward, Peter; McDonald, Malcolm I.; Currie, Bart J.; Carapetis, Jonathan R.

    2012-01-01

    Streptococcus pyogenes is commonly believed to be resistant to trimethoprim-sulfamethoxazole (SXT), resulting in reservations about using SXT for skin and soft tissue infections (SSTI) where S. pyogenes is involved. S. pyogenes' in vitro susceptibility to SXT depends on the medium's thymidine content. Thymidine allows S. pyogenes to bypass the sulfur-mediated inhibition of folate metabolism and, historically, has resulted in apparently reduced susceptibility of S. pyogenes to sulfur antibacterials. The low thymidine concentration in Mueller-Hinton agar (MHA) is now regulated. We explored S. pyogenes susceptibility to SXT on various media. Using two sets of 100 clinical S. pyogenes isolates, we tested for susceptibility using SXT Etests on MHA containing defibrinated horse blood and 20 mg/liter β-NAD (MHF), MHA with sheep blood (MHS), MHA alone, MHA with horse blood (MHBA), and MHA with lysed horse blood (MHLHBA). European Committee on Antibacterial Susceptibility Testing (EUCAST) breakpoints defined susceptibility (MIC, ≤1 mg/liter) and resistance (MIC, >2 mg/liter). In study 1, 99% of S. pyogenes isolates were susceptible to SXT on MHA, MHBA, and MHLHBA, with geometric mean MICs of 0.04, 0.04, and 0.05 mg/liter, respectively. In study 2, all 100 S. pyogenes isolates were susceptible to SXT on MHF, MHS, MHA, and MHLHBA with geometric mean MICs of 0.07, 0.16, 0.07, and 0.09 mg/liter, respectively. This study confirms the in vitro susceptibility of S. pyogenes to SXT, providing support for the use of SXT for SSTIs. A clinical trial using SXT for impetigo is ongoing. PMID:23052313

  7. Monitoring forest soil properties with electrical resistivity

    OpenAIRE

    Paillet, Y.; Cassagne, N.; Brun, J.J.

    2010-01-01

    Maintenance and monitoring of soil fertility is a key issue for sustainable forest management. Vital ecosystem processes may be affected by management practices which change the physical, chemical and biological properties of the soil. This study is the first in Europe to use electrical resistivity as a non-invasive method to determine forest soil properties rapidly in the field in a monitoring purpose. We explored the correlations between electrical resistivity and forest soil properties on ...

  8. Electrical resistivity tomography and magnetic surveys: applications ...

    African Journals Online (AJOL)

    A study aimed at evaluating the competence of the near surface formations as foundation materials has been undertaken at the site of the newly established Wolkite University Campus. Integrated geophysical surveys involving 2D Electrical Resistivity Tomography (ert), Vertical Electrical Sounding (ves) and magnetic ...

  9. Penicillin-susceptible Staphylococcus aureus: susceptibility testing, resistance rates and outcome of infection.

    Science.gov (United States)

    Hagstrand Aldman, Malin; Skovby, Annette; I Påhlman, Lisa

    2017-06-01

    Staphylococcus aureus (SA) is an important human pathogen that causes both superficial and invasive infections. Penicillin is now rarely used in the treatment of SA infections due to widespread resistance and a concern about the accuracy of existing methods for penicillin susceptibility testing. The aims of the present study were to determine the frequency of penicillin-susceptible SA isolates from blood and wound cultures in Lund, Sweden, and to evaluate methods for penicillin testing in SA. We also wanted to investigate if penicillin-susceptible isolates are associated with higher mortality. Hundred blood culture isolates collected 2008/2009, 140 blood culture isolates from 2014/2015, and 141 superficial wound culture strains from 2015 were examined. Penicillin susceptibility was tested with disk diffusion according to EUCAST guidelines, and results were confirmed with a cloverleaf assay and PCR amplification of the BlaZ gene. Patient data for all bacteraemia cases were extracted from medical records. The disk diffusion method with assessment of both zone size and zone edge appearance had high accuracy in our study. About 57% of bacteraemia isolates from 2008/2009 were sensitive to penicillin compared to 29% in 2014/2015 (p penicillin susceptible. There was no difference in co-morbidity or mortality rates between patients with penicillin resistant and penicillin sensitive SA bacteraemia. Disk-diffusion is a simple and reliable method to detect penicillin resistance in SA, and susceptibility rates are significant. Penicillin has many theoretical advantages and should be considered in the treatment of SA bacteraemia when susceptible.

  10. Multicenter study on antibiotic susceptibility/resistance trends in the ...

    African Journals Online (AJOL)

    Multicenter study on antibiotic susceptibility/resistance trends in the western region of Cameroon. Reine Flaviette Tchapdie Ngassam, Megne Tantse, Pierre René Fotsing Kwetche, Dorice Pascale Noukela Noumi, Jonas Kouamouo, Josué Simo Louokdom, Sandrine Gamwo Dongmo, Serge Honoré Tchoukoua, Blandine ...

  11. electrical resistivity measurements of downscaled homogenous

    African Journals Online (AJOL)

    ES Obe

    Abstract. Knowledge of electrical resistivity for reservoir rocks is crucial for a number of reservoir engineering tasks such as the determination of oil-in-place and the cal- ibration of resistivity logs. Those properties can now be predicted by numerical calculations directly on micro-CT images taken from rock fragments typically ...

  12. Electrical Resistivity Measurements of Downscaled Homogenous ...

    African Journals Online (AJOL)

    Knowledge of electrical resistivity for reservoir rocks is crucial for a number of reservoir engineering tasks such as the determination of oil-in-place and the calibration of resistivity logs. Those properties can now be predicted by numerical calculations directly on micro-CT images taken from rock fragments typically having a ...

  13. Antimicrobial susceptibility and glycopeptide-resistance of enterococci in vegetables

    Directory of Open Access Journals (Sweden)

    Ida Torre

    2010-03-01

    Full Text Available

    Background: Vancomycin-resistant enterococci (VRE, often responsible for nosocomial infections, have frequently been isolated from animal and vegetable foods. In our study we evaluated the antibiotic susceptibility of enterococci isolated from eight types of vegetables randomly selected from grocery stores in Naples.

    Methods: From July to November 2008, we analyzed 150 samples: the bacteria were isolated with standardized methods and antibiotic susceptibility was determined using the disc diffusion method. The resistance to vancomycin versus other antibiotics was assessed by the Kappa test.

    Results: 70% of the samples, mainly parsley (96.2%, showed enterococci. Of these, 59.1% belonged to the species Enterococcus faecium. Strains resistant to vancomycin and teicoplanin were isolated respectively in 47.6% and 49.5% of the samples: the first one mainly in curly endive (72.7% and the second one in parsley (76.9%. Almost all the isolated strains showed resistance to methicillin (89%, kanamycin (82% and cephalothin (68%. The Kappa test showed statistically significant associations between resistance to vancomycin and resistance to teicoplanin, erythromycin, methicillin, tetracycline and chloramphenicol.

    Conclusions: Because of the possible involvement of food in the transmission of resistant micro-organisms to human intestinal microbiota, our data may provide the basis for future studies.

  14. Vancomycin-resistant enterococci: validation of susceptibility testing and in vitro activity of novel antibiotics

    DEFF Research Database (Denmark)

    Rathe, Mathias; Lise, Kristensen,; Ellermann-Eriksen, Svend

    Vancomycin-resistant enterococci: validation of susceptibility testing and in vitro activity of novel antibiotics......Vancomycin-resistant enterococci: validation of susceptibility testing and in vitro activity of novel antibiotics...

  15. Electrical Resistivity of Alkaline Earth Elements.

    Science.gov (United States)

    1976-12-01

    liquid state. Van Zytveld et al. [50] (curve 28) found a very small temperature depend- ence of the electrical resistivity. Scala and Robertson [51...should have a weak negative temperature dependence. The data of Scala et al. have been normalized by matching their values with the data of Van Zytveld et...Silver and Magnesium," Phys. Rev., B2 (8), 2961-72, 1970. (E45213) 49. Powell, R. W., Hickman, M. J., and Tye, R. P., "The Thermal and Electrical

  16. High electrical resistivity of CVD-diamond

    OpenAIRE

    Manca, Jean; Nesladek, Milos; Neelen, M; QUAEYHAEGENS, Carl; De Schepper, Luc; de Ceuninck, Ward

    1999-01-01

    Due to its combination of excellent thermo-mechanical properties and electrical properties such as the high electrical resistivity and high dielectric strength, diamond seems a promising material for specialized dielectric applications. Due to the great advances in the growth technology of diamond films by chemical vapour deposition (CVD) on e.g. Si-substrates, new applications can be expected in microelectronics. An important technological result for dielectric applications is that high elec...

  17. Methicillin resistant Staphylococcus aureus (MRSA in India: Prevalence & susceptibility pattern

    Directory of Open Access Journals (Sweden)

    Indian Network for Surveillance of Antimicrobial Resistance (INSAR group, India

    2013-01-01

    Full Text Available Background & objectives: Methicillin resistant Staphylococcus aureus (MRSA is endemic in India and is a dangerous pathogen for hospital acquired infections. This study was conducted in 15 Indian tertiary care centres during a two year period from January 2008 to December 2009 to determine the prevalence of MRSA and susceptibility pattern of S. aureus isolates in India. Methods: All S. aureus isolates obtained during the study period in the participating centres were included in the study. Each centre compiled their data in a predefined template which included data of the antimicrobial susceptibility pattern, location of the patient and specimen type. The data in the submitted templates were collated and analysed. Results: A total of 26310 isolates were included in the study. The overall prevalence of methicillin resistance during the study period was 41 per cent. Isolation rates for MRSA from outpatients, ward inpatients and ICU were 28, 42 and 43 per cent, respectively in 2008 and 27, 49 and 47 per cent, respectively in 2009. The majority of S. aureus isolates was obtained from patients with skin and soft tissue infections followed by those suffering from blood stream infections and respiratory infections. Susceptibility to ciprofloxacin was low in both MSSA (53% and MRSA (21%. MSSA isolates showed a higher susceptibility to gentamicin, co-trimoxazole, erythromycin and clindamycin as compared to MRSA isolates. No isolate was found resistant to vancomycin or linezolid. Interpretation & conclusions: The study showed a high level of MRSA in our country. There is a need to study epidemiology of such infections. Robust antimicrobial stewardship and strengthened infection control measures are required to prevent spread and reduce emergence of resistance.

  18. Electrical Resistivity of Aluminum and Manganese.

    Science.gov (United States)

    1983-03-01

    James, and C. Y. Ho 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK AREA & WORK UNIT NUMBERS Thermophysical and Elecronic...investigated area . Interested readers may refer to refs. 251-269 for information on the electrical resistivity of deformed aluminum. Last but not... Wernick , 3.H., ’Low Temperature Resistance Measurements as a Means of Studying Impurity Distributions in Zone Refined Ingots of Met- als,’ Met. Trans

  19. Electrical resistivity determination of subsurface layers, subsoil ...

    African Journals Online (AJOL)

    A geophysical investigation involving the electrical resistivity method was carried out at a site located in the eastern part of Akungba-Akoko, southwestern Nigeria. The aim of the investigation was to characterize the site according to subsurface lithologic layering, subsoil competence and soil corrosivity, which may affect the ...

  20. electrical resistivity measurements of downscaled homogenous

    African Journals Online (AJOL)

    ES Obe

    The experimental data used to validate those pre- dictions are obtained on conventional cores having bulk volumes of the order of .... modeling hydrocarbon displacement by water spontaneous imbibition and/or water injec- ... Electrical Resistivity Measurements for Network Model Validation. 9. Figure 1: Schematic of Pc-RI ...

  1. ON THE APPLICATION OF THE ELECTRICAL RESISTIVITY ...

    African Journals Online (AJOL)

    ... an approximate N-S trend. The competent materials underlie the premises. It is concluded from these that the buildings failed due to the flow of the incompetent clays on which they were founded. KEY WORDS: Electrical Resistivity, Foundation Failure, Case Study. Global Jnl Geological Sciences. Vol.2(1) 2004: 139-151 ...

  2. Integrated VLF - Electromagnetic And Electrical Resistivity Survey ...

    African Journals Online (AJOL)

    ... beneath BH5 for confined fractures. Borehole yields vary from 0.33 - 2.0 l/s, where two abortive (dry) boreholes (BH1 & 2) were previously drilled. KEY WORDS: VLF - EM, Electrical Resistivity, Linear Features, Groundwater Development, Basement Complex Area. Global Journal of Geological Sciences Vol.3(1) 2005: 71- ...

  3. On equivalent resistance of electrical circuits

    Science.gov (United States)

    Kagan, Mikhail

    2015-01-01

    While the standard (introductory physics) way of computing the equivalent resistance of nontrivial electrical circuits is based on Kirchhoff's rules, there is a mathematically and conceptually simpler approach, called the method of nodal potentials, whose basic variables are the values of the electric potential at the circuit's nodes. In this paper, we review the method of nodal potentials and illustrate it using the Wheatstone bridge as an example. We then derive a closed-form expression for the equivalent resistance of a generic circuit, which we apply to a few sample circuits. The result unveils a curious interplay between electrical circuits, matrix algebra, and graph theory and its applications to computer science. The paper is written at a level accessible by undergraduate students who are familiar with matrix arithmetic. Additional proofs and technical details are provided in appendices.

  4. Electrical resistivity mechanism in magnetorheological elastomer

    Energy Technology Data Exchange (ETDEWEB)

    Kchit, N; Bossis, G [LPMC UMR-CNRS 6622, University of Nice Sophia Antipolis, 06108 Nice cedex 2 (France)], E-mail: bossis@unice.fr

    2009-05-21

    Magnetorheological elastomers (MREs) are smart materials made by aligning magnetic microparticles inside a liquid polymer. Once the polymer is cured, this anisotropic structure is kept, giving to the composite new properties such as a large change in electrical resistivity with applied pressure. In order to understand the conduction mechanism in such composites, the influence of pressure on the electrical resistivity of metal powders without polymer was first investigated. It was found that the initial resistivity of metal powder at zero pressure is about 10{sup 8} {omega} cm for pure nickel powder and 10{sup 6} {omega} cm for silver coated nickel particles. The piezoresistivity of the powders follows a power law with a coefficient close to (-1) at high compression, which allows the thickness of the oxide layer to be determined. The change in resistance with pressure was found to be an order of magnitude larger for a MRE composite than for the same volume fraction of fillers dispersed randomly in the polymer. The filler particles have a high surface roughness, and when particles are brought into contact under pressure, the electric current takes place via microcontacts between asperities. The model of tunnel resistance developed in this study includes the roughness parameters and the thickness of the oxide layer found with the powder and introduces the thickness of the polymer layer as a new parameter. This model well reproduces experimental curves for piezoresistivity of composites allowing the thickness of the insulating polymer layer strongly adsorbed on the surface of particles to be determined.

  5. Identification of lamb flocks susceptible and resistant against Brachiaria poisoning

    Directory of Open Access Journals (Sweden)

    Rayane C. Pupin

    2016-05-01

    Full Text Available Abstract: This study was designed to assess the influence of genetic resistance against brachiaria poisoning in sheep. Two groups of sheep, one identified as susceptible (formed by two ewes and one ram and the other as resistant against brachiaria poisoning (formed by three ewes and one ram were selected. Sheep considered susceptible were those that presented clinical signs of brachiaria poisoning at any time of their life; resistant sheep were those that even raised on Brachiaria spp. pastures, did not developed any sign of the poisoning during their life. The offspring of the two flocks (15 lambs from the sensitive flock and 9 lambs from the resistant flock were placed into brachiaria pasture (initially Brachiaria decumbens and B. brizantha,and only B. decumbens after weaning and followed up during two years (2013-2014. The determination of protodioscin levels in B. decumbens pasture was performed only in 2014 and revealed significant amounts of the toxic principle. Eleven lambs of the susceptible group were affected to some degree of brachiaria poisoning and six died; no lamb of the resistant group was affected. Clinical signs consisted of varying degrees of subcutaneous edema of the face and, erythema and loss of hair of the ears, crusts on the skin of ears, around the eyes and on planum nasale, scar deformation of the ears, and bilateral ocular discharge; affected lambs also sought for shadowy shelters and they were poor doers. Several sheep recovered from the condition and then relapsed. Necropsy findings in six lambs included pale mucous membranes, emaciation, dermatitis, scar deformation of the ears, large yellow livers with marked lobular pattern, and moderate infestation by Haemonchus contortus. Histologically the liver lesions were similar in all necropsied lambs but with varying degrees of severity; they were consistent with brachiaria poisoning and included architectural disruption of hepatocellular trabecula, clusters of foamy

  6. Bacterial resistance and susceptibility to antimicrobial peptides and peptidomimetics

    DEFF Research Database (Denmark)

    Citterio, Linda

    Bacterial resistance to conventional antibiotics has become a global challenge and there is urgent need for new and alternative compounds. Antimicrobial peptides (AMPs) are under investigation as novel antibiotics. These are part of the immune defense of all living organisms; hence, they represent...... are one class of such synthetic modified peptides. The purpose of this PhD project was to determine the antibacterial spectrum and potential use of synthetic antimicrobial peptides and peptidomimetics. Another key investigation has been the experimental development of resistance to these novel...... in vivo may be lower than predicted from standard antimicrobial susceptibility testing. Unfortunately bacteria can easily adapt to AMPs in laboratory settings and we found (Manuscript 2) that in Escherichia coli through an adaptive evolution experiment. We hypothesized that evolution of resistance...

  7. Estimating soil suction from electrical resistivity

    Science.gov (United States)

    Piegari, E.; Di Maio, R.

    2013-09-01

    Soil suction and resistivity strongly depend on the degree of soil saturation and, therefore, both are used for estimating water content variations. The main difference between them is that soil suction is measured using tensiometers, which give point information, while resistivity is obtained by tomography surveys, which provide distributions of resistivity values in large volumes, although with less accuracy. In this paper, we have related soil suction to electrical resistivity with the aim of obtaining information about soil suction changes in large volumes, and not only for small areas around soil suction probes. We derived analytical relationships between soil matric suction and electrical resistivity by combining the empirical laws of van Genuchten and Archie. The obtained relationships were used to evaluate maps of soil suction values in different ashy layers originating in the explosive activity of the Mt Somma-Vesuvius volcano (southern Italy). Our findings provided a further example of the high potential of geophysical methods in contributing to more effective monitoring of soil stress conditions; this is of primary importance in areas where rainfall-induced landslides occur periodically.

  8. Estimating soil suction from electrical resistivity

    Directory of Open Access Journals (Sweden)

    E. Piegari

    2013-09-01

    Full Text Available Soil suction and resistivity strongly depend on the degree of soil saturation and, therefore, both are used for estimating water content variations. The main difference between them is that soil suction is measured using tensiometers, which give point information, while resistivity is obtained by tomography surveys, which provide distributions of resistivity values in large volumes, although with less accuracy. In this paper, we have related soil suction to electrical resistivity with the aim of obtaining information about soil suction changes in large volumes, and not only for small areas around soil suction probes. We derived analytical relationships between soil matric suction and electrical resistivity by combining the empirical laws of van Genuchten and Archie. The obtained relationships were used to evaluate maps of soil suction values in different ashy layers originating in the explosive activity of the Mt Somma-Vesuvius volcano (southern Italy. Our findings provided a further example of the high potential of geophysical methods in contributing to more effective monitoring of soil stress conditions; this is of primary importance in areas where rainfall-induced landslides occur periodically.

  9. Electrical resistance tomography from measurements inside a steel cased borehole

    Science.gov (United States)

    Daily, William D.; Schenkel, Clifford; Ramirez, Abelardo L.

    2000-01-01

    Electrical resistance tomography (ERT) produced from measurements taken inside a steel cased borehole. A tomographic inversion of electrical resistance measurements made within a steel casing was then made for the purpose of imaging the electrical resistivity distribution in the formation remotely from the borehole. The ERT method involves combining electrical resistance measurements made inside a steel casing of a borehole to determine the electrical resistivity in the formation adjacent to the borehole; and the inversion of electrical resistance measurements made from a borehole not cased with an electrically conducting casing to determine the electrical resistivity distribution remotely from a borehole. It has been demonstrated that by using these combined techniques, highly accurate current injection and voltage measurements, made at appropriate points within the casing, can be tomographically inverted to yield useful information outside the borehole casing.

  10. Antimicrobial resistance in methicillin susceptible and methicillin resistant Staphylococcus pseudintermedius of canine origin

    DEFF Research Database (Denmark)

    Moodley, Arshnee; Damborg, Peter Panduro; Nielsen, Søren Saxmose

    2014-01-01

    Staphylococcus pseudintermedius is a commensal and a common opportunistic pathogen causing mainly infections of the integumentary system in dogs. The recent emergence of multidrug-resistant S. pseudintermedius isolates, in particular methicillin-resistant strains (MRSP) is a threat to small animal...... health and highlights the need for antimicrobial resistance surveillance to detect trends and potentially perform timeous interventions. We systematically reviewed 202 published articles to investigate temporal changes in antimicrobial resistance in clinical and commensal S. pseudintermedius isolated...... from dogs in 27 countries between 1980 and 2013. Resistance to the most common antimicrobials tested for in published studies and important for the treatment of staphylococcal infections in dogs were assessed separately for methicillin resistant (MRSP) and methicillin susceptible (MSSP) isolates...

  11. Complex Electrical Resistivity for Monitoring DNAPL Contamination

    Energy Technology Data Exchange (ETDEWEB)

    Stephen R. Brown; David Lesmes; John Fourkas

    2003-09-12

    Nearly all Department of Energy (DOE) facilities have landfills and buried waste areas. Of the various contaminants present at these sites, dense non-aqueous phase liquids (DNAPL) are particularly hard to locate and remove. There is an increasing need for external or non-invasive sensing techniques to locate DNAPLs in the subsurface and to track their spread and monitor their breakdown or removal by natural or engineered means. G. Olhoeft and colleagues have published several reports based on laboratory studies using the complex resistivity method which indicate that organic solvents, notably toluene, PCE, and TCE, residing in clay-bearing soils have distinctive electrical signatures. These results have suggested to many researchers the basis of an ideal new measurement technique for geophysical characterization of DNAPL pollution. Encouraged by these results we proposed to bring the field measurement of complex resistivity as a means of pollution characterization from the conceptual stage to practice. We planned to document the detectability of clay-organic solvent interactions with geophysical measurements in the laboratory, develop further understanding of the underlying physical and chemical mechanisms, and then apply these observations to develop field techniques. As with any new research endeavor we note the extreme importance of trying to reproduce the work of previous researchers to ensure that any effects observed are due to the physical phenomena occurring in the specimen and not due to the particular experimental apparatus or method used. To this end, we independently designed and built a laboratory system, including a sample holder, electrodes, electronics, and data analysis software, for the measurement of the complex electrical resistivity properties of soil contaminated with organic solvents. The capabilities and reliability of this technique were documented. Using various standards we performed measurement accuracy, repeatability, and noise immunity

  12. Histological responses to downy mildew in resistant and susceptible grapevines.

    Science.gov (United States)

    Liu, Ruiqi; Wang, Lan; Zhu, Jiali; Chen, Tingting; Wang, Yuejin; Xu, Yan

    2015-01-01

    Downy mildew in grapevines, caused by Plasmopara viticola, is a very serious disease throughout the grape-producing nations, especially in more humid climates. Downy mildew mainly affects the cultivated varieties of Vitis vinifera. A promising way to minimize or eliminate P. viticola infections is by the adoption of resistant cultivars. Chinese wild grapevines are reported to possess resistance to many fungal diseases. In this study, three Chinese wild grapevines (Vitis pseudoreticulata Baihe-35-1, Vitis davidii var. cyanocarpa Langao-5, and Vitis piasezkii Liuba-8) and a European cultivated variety (V. vinifera cv. Pinot noir) were inoculated with P. viticola, and a histological survey was undertaken. Macroscopic observations revealed no sporulation in V. piasezkii Liuba-8, little sporulation in V. pseudoreticulata Baihe-35-1 and V. davidii var. cyanocarpa Langao-5, but serious sporulation in V. vinifera cv. Pinot noir. Aniline blue staining indicated callose deposition in V. pseudoreticulata Baihe-35-1, V. davidii var. cyanocarpa Langao-5, and V. piasezkii Liuba-8. Cells with distinctive fluorescence were also observed in V. pseudoreticulata Baihe-35-1. After staining with 3,3-diaminobenzidine, production of H₂O₂ was observed early on, after infection in V. davidii var. cyanocarpa Langao-5 and V. piasezkii Liuba-8. No H₂O₂ accumulation was observed in V. vinifera cv. Pinot noir. It is concluded that V. piasezkii Liuba-8 should be classified as "highly resistant" to downy mildew, V. pseudoreticulata Baihe-35-1 and V. davidii var. cyanocarpa Langao-5 as "resistant," and V. vinifera Pinot noir as "susceptible." The possible roles of stomatal callose deposition in the defense r6eactions of the mildew-resistant grapevines are discussed.

  13. Correlation between Wear Resistance and Lifetime of Electrical Contacts

    Directory of Open Access Journals (Sweden)

    Jian Song

    2012-01-01

    Full Text Available Electrical contacts are usually plated in order to prevent corrosion. Platings of detachable electrical contacts experience wear because of the motion between contacts. Once the protecting platings have been worn out, electrical contacts will fail rapidly due to corrosion or fretting corrosion. Therefore the wear resistance of the platings is a very important parameter for the long lifetime of electrical contacts. Many measures which improve the wear resistance can diminish the conductivity of the platings. Due to the fact that platings of electrical contacts must have both a high wear resistance and a high electrical conductivity, the manufacturing of high performance platings of electrical contacts poses a great challenge. Our study shows firstly the correlation between the wear resistance of platings and lifetime of electrical contacts and then the measures, which improve the wear resistance without impairing the electrical performance of the contacts.

  14. Isoniazid resistance among rifampicin-susceptible Mycobacterium tuberculosis isolates from tuberculosis patients

    Directory of Open Access Journals (Sweden)

    Jyoti Arora

    2016-01-01

    Conclusion: INH resistance among RIF-susceptible isolates was present in 10–15% of the total cases. Among these cases, the use of RIF susceptibility alone will fail to detect INH resistance. Since higher rates of failure, relapse, or acquired resistance are linked with INH resistance, rollout of techniques focusing on RIF resistance must, therefore, be accompanied by strict monitoring for better management of patients.

  15. Electrical Resistance Tomography imaging of concrete

    KAUST Repository

    Karhunen, Kimmo

    2010-01-01

    We apply Electrical Resistance Tomography (ERT) for three dimensional imaging of concrete. In ERT, alternating currents are injected into the target using an array of electrodes attached to the target surface, and the resulting voltages are measured using the same electrodes. These boundary measurements are used for reconstructing the internal (3D) conductivity distribution of the target. In reinforced concrete, the metallic phases (reinforcing bars and fibers), cracks and air voids, moisture gradients, and the chloride distribution in the matrix carry contrast with respect to conductivity. While electrical measurements have been widely used to characterize the properties of concrete, only preliminary results of applying ERT to concrete imaging have been published so far. The aim of this paper is to carry out a feasibility evaluation with specifically cast samples. The results indicate that ERT may be a feasible modality for non-destructive evaluation of concrete. © 2009 Elsevier Ltd. All rights reserved.

  16. Electrical Resistivity of Vanadium and Zirconium.

    Science.gov (United States)

    1982-12-01

    Purdue Univ., 2595 Yeager RA., W. Lafayette,IN 47906 11. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Defense Technical Information Center...D.S.. ’Electrical Resistivity of Zircon ’- ium Alloys,’ UShIC Rept. 0SI-4370, 23-4 (1968). 61 136. Clinard, F.I., Jr. and Kempter, C.P., ’Low...Hake, 1.1., ’Localized Magnetic Impurity States in Titan- inm, Zirconium, and Hafnium .’ Phys. Rev. A. M,)(l), 142-9 (1965). 138. Powell, R.W. and Tye

  17. Selective susceptibility to nanosecond pulsed electric field (nsPEF) across different human cell types.

    Science.gov (United States)

    Gianulis, Elena C; Labib, Chantelle; Saulis, Gintautas; Novickij, Vitalij; Pakhomova, Olga N; Pakhomov, Andrei G

    2017-05-01

    Tumor ablation by nanosecond pulsed electric fields (nsPEF) is an emerging therapeutic modality. We compared nsPEF cytotoxicity for human cell lines of cancerous (IMR-32, Hep G2, HT-1080, and HPAF-II) and non-cancerous origin (BJ and MRC-5) under strictly controlled and identical conditions. Adherent cells were uniformly treated by 300-ns PEF (0-2000 pulses, 1.8 kV/cm, 50 Hz) on indium tin oxide-covered glass coverslips, using the same media and serum. Cell survival plotted against the number of pulses displayed three distinct regions (initial resistivity, logarithmic survival decline, and residual resistivity) for all tested cell types, but with differences in LD 50 spanning as much as nearly 80-fold. The non-cancerous cells were less sensitive than IMR-32 neuroblastoma cells but more vulnerable than the other cancers tested. The cytotoxic efficiency showed no apparent correlation with cell or nuclear size, cell morphology, metabolism level, or the extent of membrane disruption by nsPEF. Increasing pulse duration to 9 µs (0.75 kV/cm, 5 Hz) produced a different selectivity pattern, suggesting that manipulation of PEF parameters can, at least for certain cancers, overcome their resistance to nsPEF ablation. Identifying mechanisms and cell markers of differential nsPEF susceptibility will critically contribute to the proper choice and outcome of nsPEF ablation therapies.

  18. Can Pierce’s disease resistance introgressed into Vitis vinifera be translocated from a resistant rootstock to a susceptible scion?

    Science.gov (United States)

    The goal of this research is to evaluate the potential of a non-transgenic, PD-resistant Vitis vinifera selection used as an experimental rootstock to confer systemic resistance to PD-susceptible V. vinifera scions. Source of PD-susceptible plant material was the wine grape variety ‘Chardonnay’, kno...

  19. Appetite Response among Those Susceptible or Resistant to Obesity

    Directory of Open Access Journals (Sweden)

    Rachel C. Brown

    2014-01-01

    Full Text Available An alternative approach in determining cause, treatment, and prevention of obesity is to study those who appear resistant to the obesogenic environment. We examined appetite responses in 33 obesity resistant individuals (ORI versus 28 obesity susceptible individuals (OSI. Fingerprick blood samples to measure ghrelin, total peptide YY (PYY, leptin, glucose, and insulin along with appetite ratings were collected at baseline and 15, 30, 60, 120, and 180 min following consumption of a standardized meal. Fasting, area under the curve (AUC, peak/nadir, and time to peak/nadir were compared. Participants completed the three factor eating questionnaire (TFEQ. No significant differences were observed for ghrelin or PYY. Higher leptin concentrations in the OSI disappeared after controlling for percent body fat (%BF. Significant differences in appetite ratings included a lower hunger nadir among OSI compared with ORI (P=0.017. Dietary restraint (P<0.001 and disinhibition (P<0.001 were lower in ORI compared with OSI, with and without adjustment for %BF. Given the differential body weight of the study groups, similar observed ghrelin concentrations were unexpected, perhaps indicating OSI and ORI respond differently to the same ghrelin concentration. Also ORI response to hunger appears different as they exhibit lower levels of dietary restraint and disinhibition compared with OSI.

  20. (VLF-EM) and electrical resistivity survey for evaluation of ...

    African Journals Online (AJOL)

    ENSEMBLES

    2016-05-26

    May 26, 2016 ... complex. Key words: Weathered layer, geological fissures, aquifer, electrical resistivity, geoelectric section, electromagnetic. ... Electrical Resistivity methods was used in this study to delineating geological deep ... partial curve matching were then used for a quantitative computer iteration using the Resist ...

  1. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

    The article gives an overview of electrical resistance alloys and alloys with low thermal expansion. The electrical resistance alloys comprise resistance alloys, heating alloys and thermostat alloys. The low expansion alloys comprise alloys with very low expansion coefficients, alloys with very low...

  2. Antibiotic susceptibility of methicillin-resistant and methicillin-susceptible coagulase-negative staphylococci isolated from bovine mastitis.

    Science.gov (United States)

    Bochniarz, M; Wawron, W

    2011-01-01

    The aim of the present study was to evaluate the antibiotic susceptibility of methicillin-susceptible (MS) and methicillin-resistant (MR) coagulase-negative Staphylococcus (CNS) strains isolated from milk of cows with mastitis. The study was conducted on 100 CNS strains (20 MRCNS and 80 MSCNS) isolated from milk samples of 86 cows from the Lublin (Poland) region farms. Antibiotic susceptibility of microorganisms was evaluated using the disc-diffusion method on the Mueller-Hinton agar according to the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS). The highest efficacy against MSCNS was demonstrated for cephalosporin antibiotics, i.e. cefacetril (91.3%), ceftiofur (67.5%), cefoperazone (66.3%) and cephalexin (60.0% of susceptible MSCNS strains). Moreover, a high percentage of vancomycin-susceptible strains was demonstrated (83.8%). The activity of combination of amoxicillin with clavulanic acid and gentamicin was found weaker (63.8% and 61.3% of susceptible strains, respectively). About 50.0% of MSCNS were susceptible to erythromycin, enrofloxacine and amoxicillin. A large proportion of CNS was resistant to neomycin, penicillin, tetracycline, streptomycin, lincomycin and ampicillin (28.8%, 30.0%, 31.3%, 31.3%, 33.8% and 33.8% of susceptible strains, respectively). The highest percentage of MRCNS was susceptible to vancomycin (75.0%), erythromycin (65.0%) and streptomycin (50.0%). Their susceptibility to enrofloxacine (35.0%) as well as gentamicin and tetracycline (30.0%) was markedly lower. The lowest activity was found for lincomycin and neomycin (20.0% of susceptible MRCNS strains, each).

  3. Sputter-Resistant Materials for Electric Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase 2 project shall develop sputter-resistant materials for use in electric propulsion test facilities and for plume shields on spacecraft using electric...

  4. Negative electric susceptibility and magnetism from translational invariance and rotational invariance

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Je Huan, E-mail: koo@kw.ac.kr

    2015-02-01

    In this work we investigate magnetic effects in terms of the translational and rotational invariances of magnetisation. Whilst Landau-type diamagnetism originates from translational invariance, a new diamagnetism could result from rotational invariance. Translational invariance results in only conventional Landau-type diamagnetism, whereas rotational invariance can induce a paramagnetic susceptibility for localised electrons and also a new kind of diamagnetism that is specific to conducting electrons. In solids, the moving electron shows a paramagnetic susceptibility but the surrounding screening of electrons may produce a new diamagnetic response by Lenz's law, resulting in a total susceptibility that tends to zero. For electricity, similar behaviours are obtained. We also derive the DC-type negative electric susceptibility via two methods in analogy with Landau diamagnetism. - Highlights: • The translational invariance of magnetisation. • The rotational invariance of magnetisation. • An electron attached to an electric vortex. • A kind of Landau paramagnetism. • A kind of Pauli diamagnetism.

  5. Disinfectant-susceptibility of multi-drug-resistant Mycobacterium tuberculosis isolated in Japan

    Directory of Open Access Journals (Sweden)

    Noriko Shinoda

    2016-02-01

    Full Text Available Abstract Background Multi-drug-resistant Mycobacterium tuberculosis has been an important problem in public health around the world. However, limited information about disinfectant-susceptibility of multi-drug-resistant strain of M. tuberculosis was available. Findings We studied susceptibility of several Japanese isolates of multi-drug-resistant M. tuberculosis against disinfectants, which are commonly used in clinical and research laboratories. We selected a laboratory reference strain (H37Rv and eight Japanese isolates, containing five drug-susceptible strains and three multi-drug-resistant strains, and determined profiles of susceptibility against eight disinfectants. The M. tuberculosis strains were distinguished into two groups by the susceptibility profile. There was no relationship between multi-drug-resistance and disinfectant-susceptibility in the M. tuberculosis strains. Cresol soap and oxydol were effective against all strains we tested, regardless of drug resistance. Conclusions Disinfectant-resistance is independent from multi-drug-resistance in M. tuberculosis. Cresol soap and oxydol were effective against all strains we tested, regardless of drug resistance.

  6. Inhibition of ACCase220 and ACCase240 isozymes from sethoxydim-resistant and -susceptible maize hybrids.

    Science.gov (United States)

    Incledon, B J; Hall, J C

    1999-01-01

    Acetyl-coenzyme A carboxylase (ACCase) isozymes were separated from cyclohexanedione-resistant and -susceptible maize. ACCase240 from resistant maize was 3.7-, >77-, and 12.8-fold more resistant to inhibition by clethodim, sethoxydim, and tralkoxydim, respectively, than ACCase240 from susceptible maize. The resistant ACCase240 preparation had 3.0-fold more protein and 14.5-fold lower specific activity than susceptible ACCase240. Resistant ACCase240 has a V(max) 5.5-fold lower than that of susceptible ACCase240, whereas apparent K(m) values were similar. ACCase220 from resistant maize was >25- and 7.2-fold more resistant to inhibition by sethoxydim and tralkoxydim, respectively, than susceptible ACCase220 but was inhibited to the same extent by clethodim. In summary, sethoxydim-resistant corn has an altered herbicide-resistant ACCase220 isozyme and increased expression of a less efficient, herbicide-resistant ACCase240 isozyme. However, to what extent alteration of both isozymes contributes to sethoxydim resistance is not clear.

  7. Application of Three Electrical Resistivity Arrays to Evaluate ...

    African Journals Online (AJOL)

    ADOWIE PERE

    https://dx.doi.org/10.4314/jasem.v21i6.36. Keywords: Electrical resistivity array; fractured zones; finite element method; 2-D models; resolution, mean absolute error. Ambiguity in the interpretation of electrical resistivity dataset as well as other geophysical datasets can be reduced by numerical modelling. This allows one to ...

  8. Evaluation of electrical resistivity anisotropy in geological mapping ...

    African Journals Online (AJOL)

    user

    However, the combination of the anisotropy polygons and the iso-resistivity map has reduced the ambiguity inherent in using a single geophysical parameter. Key words: Electrical resistivity anisotropy, radial vertical electrical sounding, anisotropy polygons. INTRODUCTION. The geological mapping in the Precambrian, ...

  9. Gentamicin Susceptibility among a Sample of Multidrug-Resistant Neisseria gonorrhoeae Isolates in India.

    Science.gov (United States)

    Bala, Manju; Singh, Vikram; Bhargava, Aradhana; Kakran, Monika; Joshi, Naveen Chandra; Bhatnagar, Ravi

    2016-12-01

    Antimicrobial susceptibility testing of 258 Neisseria gonorrhoeae isolates by Etest determined that 60.1% were multidrug resistant (MDR), while 5% of the strains had decreased susceptibility to currently recommended extended-spectrum cephalosporins (ESCs). Among these, 84.5% of MDR strains and 76.9% of strains that had decreased susceptibility to ESCs were susceptible to gentamicin. No MDR isolate was resistant to gentamicin. These in vitro results suggest that gentamicin might be an effective treatment option for the MDR strains and in dual therapy for gonorrhea. However, further research regarding the clinical treatment outcomes is essential. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  10. Resistance and differential susceptibility of Bidens pilosa and B. subalternans biotypes to ALS-inhibiting herbicides

    Directory of Open Access Journals (Sweden)

    López-Ovejero Ramiro Fernando

    2006-01-01

    Full Text Available The frequent application of herbicides in agricultural areas may select resistant biotypes in weed populations, whose biological characteristics influence the speed and patterns of resistance. This research aims to charactere, simultaneously, resistance patterns and differential susceptibility of Bidens pilosa and B. subalternans biotypes to ALS-inhibiting herbicides of the imidazolinone and sulfonylurea chemical groups. Six hairy beggarticks biotypes, four suspected resistant and two known susceptible, were treated with eight rates of chlorimuron-ethyl or imazethapyr, in greenhouse conditions. Percent control and percent fresh weight of the plants were evaluated at 28 days after the application. B. subalternans is less susceptible to ALS-inhibiting herbicides than B. pilosa; B. subalternans biotypes were more resistant than B. pilosa biotypes; there are B. pilosa and B. subalternans biotypes with cross resistance to the ALS-inhibiting herbicides of the sulfonylurea and imidazolinone groups; there are different patterns of cross resistance to the diverse groups of ALS-inhibiting herbicides.

  11. Germination and emergence characteristics of triazine-susceptible and triazine-resistant biotypes of Solanum nigrum.

    NARCIS (Netherlands)

    Kremer, E.; Lotz, L.A.P.

    1998-01-01

    1. Seedling emergence patterns of triazine-susceptible and triazine-resistant Solanum nigrum in the field were studied in Wageningen, the Netherlands. Emergence patterns were similar in the first year, but in the second year resistant seedlings emerged faster and the number of resistant seedlings

  12. Laboratory Electrical Resistivity Studies on Cement Stabilized Soil

    OpenAIRE

    Nimi Ann Vincent; Shivashankar, R.; K N Lokesh; Jinu Mary Jacob

    2017-01-01

    Electrical resistivity measurement of freshly prepared uncured and cured soil-cement materials is done and the correlations between the factors controlling the performance of soil-cement and electrical resistivity are discussed in this paper. Conventional quality control of soil-cement quite often involves wastage of a lot of material, if it does not meet the strength criteria. In this study, it is observed that, in soil-cement, resistivity follows a similar trend as unconfined compressive st...

  13. Stylet penetration activities by Aphis craccivora (Hymenoptera: Aphididae) on plants and excised plant parts of resistant and susceptible cultivars of cowpea (Leguminosae)

    NARCIS (Netherlands)

    Annan, B.; Tingey, W.M.; Schaefers, G.A.; Tjallingii, W.F.; Backus, E.A.; Saxena, K.N.

    2000-01-01

    Direct current electrical penetration graphs (DC-EPGs) were used to analyze the stylet penetration activities of cowpea aphid, Aphis craccivora Koch, on plants of aphid-resistant (ICV-12) and aphid-susceptible (ICV-1) cultivars of cowpea, Vigna unguiculata (L.) Walpers. Aphid stylet penetration on

  14. Effect of pressure on electrical resistance of WSe single crystal

    Indian Academy of Sciences (India)

    The changes in resistance observed by Bridgman anvils up to 8.5 GPa are well- reproduced with the DAC. The sample becomes more conducting as pressure increases and around 27 GPa the electrical resistance decreases by a factor of 5. We noticed slight slope change in resistance variation with pressure beyond 20 ...

  15. Magnetic susceptibility and electrical conductivity of metallic dental materials and their impact on MR imaging artifacts.

    Science.gov (United States)

    Starcuková, Jana; Starcuk, Zenon; Hubálková, Hana; Linetskiy, Igor

    2008-06-01

    The aim of this study was to test the hypothesis that dental materials vary significantly in MR-relevant material parameters-magnetic susceptibility and electrical conductivity, and that knowledge of these parameters may be used to estimate the quality of MR imaging in the presence of devices made of such materials. Magnetic susceptibility, electrical conductivity and artifacts were evaluated for 45 standardized cylindrical samples of dental alloys and amalgams. Magnetic susceptibility was determined by fitting the phase of gradient-echo MR images to numerically modeled data. Electrical conductivity was determined by standard electrotechnical measurements. Artifact sizes were measured in spin-echo (SE) and gradient-echo (GE) images at 1.5T according to the standards of the American Society for Testing and Materials. It has been confirmed that dental materials differ considerably in their magnetic susceptibility, electrical conductivity and artifacts. For typical dental devices, magnetic susceptibility differences were found of little clinical importance for diagnostic SE/GE imaging of the neck and brain, but significant for orofacial imaging. Short-TE GE imaging has been found possible even in very close distances from dental devices made of amalgams, precious alloys and titanium alloys. Nickel-chromium and cobalt-chromium artifacts were found still acceptable, but large restorations of aluminum bronzes may preclude imaging of the orofacial region. The influence of electrical conductivity on the artifact size was found negligible. MR imaging is possible even close to dental devices if they are made of dental materials with low magnetic susceptibility. Not all materials in current use meet this requirement.

  16. In vitro susceptibility of multi-drug resistant Pseudomonas ...

    African Journals Online (AJOL)

    spectrum β- (ESBL) producing Klebsiella pneumoniae isolated from clinical specimens ... for their in vitro susceptibility to piperacillin-tazobactam 100/10μg using disc diffusion test as recommended by Clinical Laboratory Standard Institute (CLSI).

  17. Iron aluminide useful as electrical resistance heating elements

    Science.gov (United States)

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    1997-01-01

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  18. Effects of insecticides on strawberry aphid Chaetosiphon fragaefolii (Cockerell) on resistant and susceptible strawberry genotypes

    OpenAIRE

    Slobodan Milenković; Dejan Marčić; Pantelija Perić

    2011-01-01

    Strawberry aphid, Chaetosiphon fragaefolii (Cockerell), is the most important vector of strawberry virus. Breeding of genotypes resistant to this pest is an important preventive control measure, which can be compatible with rational insecticide application. The aim of the paper was to determine effects of dimethoate and deltamethrin on C. fragaefolii populations reared on two strawberry genotypes different in susceptibility: susceptible strawberry cultivar ...

  19. Transfer of innate resistance and susceptibility to Leishmania donovani infection in mouse radiation bone marrow chimaeras

    Energy Technology Data Exchange (ETDEWEB)

    Crocker, P.R.; Blackwell, J.M.; Bradley, D.J. (London School of Hygiene and Tropical Medicine (UK))

    1984-07-01

    Reciprocal radiation bone marrow chimaeras were made between H-2-compatible strains of mice innately resistant or susceptible to visceral leishmaniasis. In initial experiments, susceptibility but not resistance to Leishmania donovani could be transferred with donor bone marrow into irradiated recipients. In subsequent experiments it was possible to transfer both resistance and susceptibility. This was achieved either by selecting more radiosensitive mouse strains as susceptible recipients, or alternatively by increasing the irradiation dose for the susceptible recipients used in the initial experiments. Using the higher irradiation dose, successful transfer of resistance and susceptibility between congenic mice carrying the Lshsup(r) and Lshsup(s) alleles on the more radioresistant B10 genetic background provided firm evidence that the results obtained in this study were specifically related to expression of the Lsh gene. It is concluded that Lsh gene-controlled resistance and susceptibility to L. donovani is determined by bone marrow-derived cells. The cell type(s) involved is likely to be of the macrophage lineage.

  20. Bacteriocin Production in Vancomycin-Resistant and Vancomycin-Susceptible Enterococcus Isolates of Different Origins

    OpenAIRE

    del Campo, Rosa; Tenorio, Carmen; Jiménez-Díaz, Rufino; Rubio, Carmen; Gómez-Lus, Rafael; Baquero, Fernando; Torres, Carmen

    2001-01-01

    Bacteriocin production was determined for 218 Enterococcus isolates (Enterococcus faecalis [93] and E. faecium [125]) obtained from different origins (human clinical samples [87], human fecal samples [78], sewage [28], and chicken samples [25]) and showing different vancomycin susceptibility patterns (vancomycin resistant, all of them vanA positive [56], and vancomycin susceptible [162]). All enterococcal isolates were randomly selected except for the vancomycin-resistant ones. A total of 33 ...

  1. Frequency of Resistance and Susceptible Bacteria Isolated from Houseflies

    Directory of Open Access Journals (Sweden)

    B Davari

    2010-12-01

    Conclusion: Houseflies collected from hospitals and slaughterhouse may be involved in the spread of drug resistant bacteria and may increase the potential of human exposure to drug resistant bacteria.

  2. Resistance and differential susceptibility of Bidens pilosa and B. subalternans biotypes to ALS-inhibiting herbicides

    OpenAIRE

    Ramiro Fernando López-Ovejero; Saul Jorge Pinto de Carvalho; Marcelo Nicolai; Aluana Gonçalves Abreu; Maria Tereza Grombone-Guaratini; Roberto Estevão Bragion de Toledo; Pedro Jacob Christoffoleti

    2006-01-01

    The frequent application of herbicides in agricultural areas may select resistant biotypes in weed populations, whose biological characteristics influence the speed and patterns of resistance. This research aims to charactere, simultaneously, resistance patterns and differential susceptibility of Bidens pilosa and B. subalternans biotypes to ALS-inhibiting herbicides of the imidazolinone and sulfonylurea chemical groups. Six hairy beggarticks biotypes, four suspected resistant and two known s...

  3. In Vitro Comparative Efficacy of Voriconazole and Itraconazole against Fluconazole-Susceptible and -Resistant Cryptococcus neoformans Isolates

    OpenAIRE

    Nguyen, M. Hong; Yu, Christine Y.

    1998-01-01

    In vitro susceptibility testing for 50 clinical isolates of fluconazole-susceptible or -resistant Cryptococcus neoformans was performed with itraconazole and voriconazole. Voriconazole was more potent than itraconazole for fluconazole-susceptible isolates and as potent as itraconazole for fluconazole-susceptible dose-dependent isolates and for fluconazole-resistant isolates. For fluconazole-resistant isolates, the voriconazole and itraconazole MICs ranged from 1 to 2 μg/ml.

  4. Azasordarins: Susceptibility of Fluconazole-Susceptible and Fluconazole-Resistant Clinical Isolates of Candida spp. to GW 471558

    OpenAIRE

    Cuenca-Estrella, Manuel; Mellado, Emilia; Díaz-Guerra, Teresa M.; Monzón, Araceli; Rodríguez-Tudela, Juan L.

    2001-01-01

    The in vitro activity of the azasordarin GW 471558 was compared with those of amphotericin B, flucytosine, itraconazole, and ketoconazole against 177 clinical isolates of Candida spp. GW 471558 showed potent activity against Candida albicans, Candida glabrata, and Candida tropicalis, even against isolates with decreased susceptibility to azoles. Candida krusei, Candida parapsilosis, Candida lusitaniae, and Candida guilliermondii are resistant to GW 471558 in vitro (MICs, >128 μg/ml).

  5. 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.

  6. Detection of clindamycin susceptibility in macrolide resistant phenotypes of Staphylococcus Aureus

    Directory of Open Access Journals (Sweden)

    Goyal R

    2004-01-01

    Full Text Available The present study aimed at in vitro detection of macrolide resistant phenotypes of methicillin resistant Staphylococcus aureus (MRSA and interpretation of susceptibility tests to guide therapy. The study included 25 MRSA strains that were resistant to erythromycin and clindamycin, 25 MRSA strains that were sensitive to both erythromycin and clindamycin and 100 MRSA isolates which displayed erythromycin resistant but clindamycin susceptible phenotype. Erythromycin and clindamycin double disc susceptibility testing was done to detect inducible clindamycin resistance. Dilution susceptibility testing for clindamycin and erythromycin alone and in combination was performed for all 150 strains. Seventy-six strains showed blunting around clindamycin disc (inducible resistance. After induction with erythromycin, minimum inhibitory concentration (MIC of clindamycin was noticed to rise from atleast 16 to 256 g/mL in iMLSB phenotypes indicating inducible resistance. The detailed result analysis suggests the possible role of clindamycin in treatment of some of the erythromycin resistant isolates (non inducible, as there are multiplicity of resistance mechanisms and diversity of phenotypic expressions.

  7. Observations on the electrical resistivity of steel fibre reinforced concrete

    DEFF Research Database (Denmark)

    Solgaard, Anders Ole Stubbe; Geiker, Mette Rica; Edvardsen, Carola

    2014-01-01

    Steel fibre reinforced concrete (SFRC) is in many ways a well-known construction material, and its use has gradually increased over the last decades. The mechanical properties of SFRC are well described based on the theories of fracture mechanics. However, knowledge on other material properties......, including the electrical resistivity, is sparse. Among others, the electrical resistivity of concrete has an effect on the corrosion process of possible embedded bar reinforcement and transfer of stray current. The present paper provides experimental results concerning the influence of the fibre volume...... the observed correlation between the fibre volume fraction and the electrical resistivity of the composite (the SFRC) for conductive fibres and moisture saturated concrete. This indicates that the steel fibres were conducting when measuring the electrical resistivity by AC at 126 Hz. For partly saturated...

  8. Contribution of 3-D electrical resistivity tomography for landmines detection

    National Research Council Canada - National Science Library

    Metwaly, M; El-Qady, G; Matsushima, J; Szalai, S; Al-Arifi, N. S. N; Taha, A

    2008-01-01

    .... In this work, the 3-D electric resistivity tomography (ERT) technique is evaluated as an alternative and/or confirmation detection system for both landmine types, which are buried in different soil conditions and at different depths...

  9. Imaging voids beneath bridge bent using electrical resistivity tomography.

    Science.gov (United States)

    2014-02-01

    Five electrical resistivity tomography (ERT) profiles and borehole control were acquired beneath two bridges on the bank of the : Gasconade River in order to determine extension of the underground water-filled openings in rock encountered during a dr...

  10. Mechanism for detecting NAPL using electrical resistivity imaging

    Science.gov (United States)

    Halihan, Todd; Sefa, Valina; Sale, Tom; Lyverse, Mark

    2017-10-01

    The detection of non-aqueous phase liquid (NAPL) related impacts in freshwater environments by electrical resistivity imaging (ERI) has been clearly demonstrated in field conditions, but the mechanism generating the resistive signature is poorly understood. An electrical barrier mechanism which allows for detecting NAPLs with ERI is tested by developing a theoretical basis for the mechanism, testing the mechanism in a two-dimensional sand tank with ERI, and performing forward modeling of the laboratory experiment. The NAPL barrier theory assumes at low bulk soil NAPL concentrations, thin saturated NAPL barriers can block pore throats and generate a detectable electrically resistive signal. The sand tank experiment utilized a photographic technique to quantify petroleum saturation, and to help determine whether ERI can detect and quantify NAPL across the water table. This experiment demonstrates electrical imaging methods can detect small quantities of NAPL of sufficient thickness in formations. The bulk volume of NAPL is not the controlling variable for the amount of resistivity signal generated. The resistivity signal is primarily due to a zone of high resistivity separate phase liquid blocking current flow through the fully NAPL saturated pores spaces. For the conditions in this tank experiment, NAPL thicknesses of 3.3 cm and higher in the formation was the threshold for detectable changes in resistivity of 3% and greater. The maximum change in resistivity due to the presence of NAPL was an increase of 37%. Forward resistivity models of the experiment confirm the barrier mechanism theory for the tank experiment.

  11. Electrical resistance tomography using steel cased boreholes as electrodes

    Science.gov (United States)

    Daily, William D.; Ramirez, Abelardo L.

    1999-01-01

    An electrical resistance tomography method using steel cased boreholes as electrodes. The method enables mapping the electrical resistivity distribution in the subsurface from measurements of electrical potential caused by electrical currents injected into an array of electrodes in the subsurface. By use of current injection and potential measurement electrodes to generate data about the subsurface resistivity distribution, which data is then used in an inverse calculation, a model of the electrical resistivity distribution can be obtained. The inverse model may be constrained by independent data to better define an inverse solution. The method utilizes pairs of electrically conductive (steel) borehole casings as current injection electrodes and as potential measurement electrodes. The greater the number of steel cased boreholes in an array, the greater the amount of data is obtained. The steel cased boreholes may be utilized for either current injection or potential measurement electrodes. The subsurface model produced by this method can be 2 or 3 dimensional in resistivity depending on the detail desired in the calculated resistivity distribution and the amount of data to constain the models.

  12. Phenolic compounds of apple cultivars resistant or susceptible to Venturia inaequalis.

    Science.gov (United States)

    Arici, Serife Evrim; Kafkas, Ebru; Kaymak, Suat; Koc, Namik Kemal

    2014-07-01

    Phenolic compounds play an important role in the plant defense mechanism and are responsible for antioxidant capacity in fruits and vegetables. It is known that the phenolics can determine in the leaves of plants which are resistant/susceptible to fungal infections. This study investigated the total phenolic compounds, content of shikimic acid from 33 different apple cultivars leaves infected with Venturia inaequalis [(Cke). Wint.] cultured in Fruit Research Station, in Egirdir, Isparta, Turkey. Leaves of apple cultivars were collected three times in an interval of 30 d from July to September in 2010, and analyzed using HPLC methods to detect changes in the amount of the phenolic compounds and shikimic acid. Total phenolic compounds and shikimic acid in resistant/moderate susceptible apple cultivars were higher than susceptible apple cultuvars, although not statistically different between resistant and susceptible apples. The content of shikimic acid was statistically higher only in the leaves of the domestic cultivar Ankara güzeli on all three dates. Recently, there have been increased studies trying to explain the resistance mechanism in plants. Natural resistance genes are investigated in some apple cultivars and new resistance varieties which have resistant genes are identified daily. Our study hold to determine the relationship between the phenolic compounds and the expression of resistance seems to be promising.

  13. Electrical Resistivity Survey For Conductive Soils At Gas Turbine ...

    African Journals Online (AJOL)

    Ten (10) vertical electrical soundings (VES) using Schlumberger configuration were carried out to delineate subsurface conductive soils for the design of earthling grid for electrical materials installation at the Gas Turbine Station, Ajaokuta, SW Nigeria. Interpretation of the resistivity data revealed three major geoelectric ...

  14. A study of the susceptibility of methicillin resistant coagulase ...

    African Journals Online (AJOL)

    They were further screened against five antiseptic agents namely; benzalkonium chloride, cetrimide, chlorhexidine gluconate, gentian violet and acriflavine by the agar dilution method. Oxacillin resistant isolates were confirmed by screening for the mecA gene by the standard PCR method. Results: Oxacillin resistant ...

  15. Genetic and sexual separation between insect resistant and susceptible Barbarea vulgaris plants in Denmark.

    Science.gov (United States)

    Toneatto, F; Nielsen, J K; Ørgaard, M; Hauser, T P

    2010-08-01

    Co-evolution between herbivores and plants is believed to be one of the processes creating Earth's biodiversity. However, it is difficult to disentangle to what extent diversification is really driven by herbivores or by other historical-geographical processes like allopatric isolation. In the cruciferous plant Barbarea vulgaris, some Danish individuals are resistant to herbivory by flea beetles (Phyllotreta nemorum), whereas others are not. The flea beetles are, in parallel, either resistant or susceptible to the plants defenses. To understand the historical-evolutionary framework of these interactions, we tested how genetically divergent resistant and susceptible plants are, using microsatellite markers. To test whether they are reproductively fully compatible, resistant and susceptible plants were grown intermixed in an outdoor experiment, and the paternity of open-pollinated offspring was determined by analysis of molecular markers. Resistant and susceptible Danish plants were genetically strongly differentiated and produced significantly fewer hybrids than expected from random mating or nearest neighbour mating. Our results suggest that the two types belong to different evolutionary lineages that have been (partly) isolated at some time, during which genetic and reproductive divergence evolved. A parsimonious scenario could be that the two plant types were isolated in different refugia during the previous ice age, from which they migrated into and met in Denmark and possibly neighbouring regions. If so, resistance and susceptibility has for unknown reasons become associated with the different evolutionary lineages.

  16. Molecular analysis and dimorphism of azole-susceptible and resistant Candida albicans isolates

    Directory of Open Access Journals (Sweden)

    Carolina Rodrigues Costa

    2011-12-01

    Full Text Available INTRODUCTION: Candida albicans is responsible for superficial or systemic infections known as candidiasis, which may be found in infected tissue as unicellular budding yeasts, hyphae, or pseudohyphae. In this study, the effects of both fluconazole and itraconazole antifungal agents on the hyphal formation and genotypic characterization of C. albicans isolates classified as either susceptible or resistant were investigated. METHODS: The hyphal production of five C. albicans isolates under the action of antifungal agents was investigated by culturing yeast on growth medium and on hyphal induction medium. The genotypic characterization was carried out for 13 isolates of C. albicans using the random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR method. RESULTS: The dimorphism analysis showed that the hyphal formation was higher in resistant than in the susceptible isolates to both azoles. The RAPD-PCR method identified the formation of two different groups. In group A, four resistant and two susceptible isolates were clustered, and in group B, one resistant and six susceptible isolates were clustered. CONCLUSIONS: Considering that hyphal formation was higher in resistant isolates in the presence of azole drugs, we confirmed that the hyphal production is closely related to susceptibility to azoles. These drugs may affect the morphogenesis of C. albicans depending on their susceptibility to these drugs. In relation to RAPD-PCR, most resistant isolates classified in group A and susceptible isolates in group B demonstrated that this method presented a similar standard between the two groups, suggesting that by this technique, a strong correlation between genotypes and fluconazole-resistant samples may be found.

  17. electrical resistivity tomography and magnetic surveys

    African Journals Online (AJOL)

    resistivity second layer of clay and/or high moisture content underlain by weathered and fresh bedrocks, and a number of vertical or near ... information on the physical or mechanical and chemical properties of rocks and soils that are ..... weathering resistant blocks, and low magnetic anomalies corresponding to the low ...

  18. Geological and Electrical Resistivity Sounding of Olokonla Area in ...

    African Journals Online (AJOL)

    Akorede

    ABSTRACT: Geological mapping and Electrical resistivity sounding were carried out in Olokonla area in Moro Local. Government of Kwara State in order to determine the apparent resistivities of the subsurface lithologies and correlate them with the exposed rocks observed during the geological mapping. The studies also ...

  19. Geological and Electrical Resistivity Sounding of Olokonla Area in ...

    African Journals Online (AJOL)

    Geological mapping and Electrical resistivity sounding were carried out in Olokonla area in Moro Local Government of Kwara State in order to determine the apparent resistivities of the subsurface lithologies and correlate them with the exposed rocks observed during the geological mapping. The studies also delineate the ...

  20. The Identification of Fatigue Resistant and Fatigue Susceptible Individuals

    Science.gov (United States)

    2008-05-01

    normalized and compared 38 to normalized SAFTE predictions. See text for details. Figure 3 Fatigue plots for fatigue susceptible vs. fatigue...has 5 seconds to press the button to get points for successful signal detections. Lower tones are given with greater frequency and responses to...address the first question, and we use predictions of the Sleep Activity Fatigue Task Effectiveness, or SAFTE model (Hursh, Redmond, Johnson, Thorne

  1. Effects of resistive bodies on DC electrical soundings

    Directory of Open Access Journals (Sweden)

    L. Alfano

    1996-06-01

    Full Text Available Some deep DC electrical soundings, performed in alpine and apenninic areas with the continuous polar dipole-dipole spread, show apparent resistivity curves with positive slopes. Measured values of apparent resistivity reach 30000 Wm. Applying the "surface charges" method we developed three dimensional mathematical models, by means of which we can state simple rules for determining the minimum extensions of the deep resistive bodies, fundamental information for a more precise interpretation of the field results.

  2. Electrical Resistivity of Concrete for Durability Evaluation: A Review

    Directory of Open Access Journals (Sweden)

    Pejman Azarsa

    2017-01-01

    Full Text Available Degradation processes in reinforced concrete structures that affect durability are partially controlled by transport of aggressive ions through the concrete microstructure. Ions are charged and the ability of concrete to hold out against transfer of ions greatly relies on its electrical resistivity. Hence, a connection could be expected between electrical resistivity of concrete and the deterioration processes such as increase in permeability and corrosion of embedded steel. Through this paper, an extensive literature review has been done to address relationship between concrete electrical resistivity and its certain durability characteristics. These durability characteristics include chloride diffusivity and corrosion of reinforcement as these have major influence on concrete degradation process. Overall, there exists an inverse or direct proportional correlation between these parameters. Evaluated results, from measuring the concrete electrical resistivity, can also be used as a great indicator to identify early age characteristics of fresh concrete and for evaluation of its properties, determination of moisture content, connectivity of the micropores, and even condition assessment of in-service structures. This paper also reviews and assesses research concerning the influential parameters such as environmental conditions and presence of steel rebar and cracks on measuring electrical resistivity of concrete. Moreover, concrete resistivity concept, application, and its various measurement techniques are introduced.

  3. Transcriptional responses of resistant and susceptible fish clones to the bacterial pathogen Flavobacterium psychrophilum.

    Directory of Open Access Journals (Sweden)

    Christelle Langevin

    Full Text Available Flavobacterium psychrophilum is a bacterial species that represents one of the most important pathogens for aquaculture worldwide, especially for salmonids. To gain insights into the genetic basis of the natural resistance to F. psychrophilum, we selected homozygous clones of rainbow trout with contrasted susceptibility to the infection. We compared the transcriptional response to the bacteria in the pronephros of a susceptible and a resistant line by micro-array analysis five days after infection. While the basal transcriptome of healthy fish was significantly different in the resistant and susceptible lines, the transcriptome modifications induced by the bacteria involved essentially the same genes and pathways. The response to F. psychrophilum involved antimicrobial peptides, complement, and a number of enzymes and chemokines. The matrix metalloproteases mmp9 and mmp13 were among the most highly induced genes in both genetic backgrounds. Key genes of both pro- and anti-inflammatory response such as IL1 and IL10, were up-regulated with a greater magnitude in susceptible animals where the bacterial load was also much higher. While higher resistance to F. psychrophilum does not seem to be based on extensive differences in the orientation of the immune response, several genes including complement C3 showed stronger induction in the resistant fish. They may be important for the variation of susceptibility to the infection.

  4. Electrically Conductive, Heat-Resistant Paint

    Science.gov (United States)

    Hribar, V. F.; Mell, R. J.

    1987-01-01

    Improved, sprayable, thermal- and electrostatic-discharge-control coating for titanium possesses excellent adhesion and high resistance to both vibration and thermal shock. Coating is improved formulation of one described in "High-Temperature Coatings for Titanium" (NPO-16222).

  5. Evaluation of Unknown Tube Well Depth Using Electrical Resistivity Method

    Directory of Open Access Journals (Sweden)

    Zainal Abidin Mohd Hazreek

    2017-01-01

    Full Text Available Electrical resistivity method has increasingly adopted in engineering, environmental, mining and archaeological studies. Systematic and proper studies of unknown civil engineering structure evaluation particularly on tube well depth was rarely being established. Conventionally, camera test or string with weight approach has been used to evaluate unknown tube well depth thus exposed to several restriction due to its expensive and time consuming. Hence, this study focused on evaluation of unknown tube well depth using indirect test with particular reference to electrical resistivity method (ERM.A single spread line of electrical resistivity survey was performed using ABEM SAS 4000 equipment set based on Wenner and Pole-dipole array in line with the tube well position. Electrical resistivity raw data was processed using RES2DINV software producing electrical resistivity tomography (ERT of the subsurface profile studied. Then, electrical resistivity value (ERV obtained from RES2DINV analyses (ERT was extracted and analysed using plotted graph (depth versus ERV specifically at tube well position based on electrical resistivity spread line performed. It was found that both array have shown some good similarity results in term of tube well depth (20 m thus able to verify the result interpreted. Both array have shown some good similarity of ERV representing groundwater (ERV = 10 – 100 Ωm and soil with water (ERV > 100 Ωm at depth of 0 – 20 m and >20 m respectively. All those interpretation have shown good agreement based on verification thru established ERV of earth materials references, geological map and nearest available boreholes data. Hence, this study has shown that the application of ERM was applicable in evaluation of unknown tube well depth which efficient in term of cost, time and environmental sustainable.

  6. [Antifungal susceptibility and drug-resistant mechanism of Trichosporon].

    Science.gov (United States)

    Kushima, Hisako; Tokimatsu, Issei; Ishii, Hiroshi; Kadota, Jun-ichi

    2015-01-01

    Most cases of deep-seated trichosporonosis develop in patients with neutropenia, but it has recently been reported that breakthrough infections with Trichosporon species can develop during the use of candin family of antifungal agents. This is due to the primary resistance of the causal fungus, Trichosporon asahii (T. asahii), to the candin agents. On the other hand, there has been a case report of infection with Trichosporon that presented high-level resistance to the azole family of antifungal agents. Therefore, the possibility that the frequent use of azole agents may lead to secondary resistance to these agents is a cause for concern. Since trichosporonosis is a relatively rare infectious disease, there has been no established breakpoint for this fungus to various antifungal agents, wherein we cannot precisely confirm its sensitivity or resistance to the agents. However, our experiment demonstrated one of the processes for acquired drug resistance, wherein the minimal inhibitory concentration of fluconazole for T. asahii was markedly elevated after its long-term in vitro exposure to the drug. Although the mechanisms for drug-resistance of Trichosporon species are unknown, it is supposed that they are the same as the mechanisms found in Candida and Aspergillus species, namely, modification of target molecules or decrease of access to the molecules. Since cases of trichosporonosis are likely to increase in the future, we believe that there is an urgent need to establish the breakpoint for T. asahii based on large-scale drug sensitivity tests, as well as to elucidate its drug-resistance mechanisms.

  7. An Experimental Study of the Electrical Contact Resistance in Resistance Welding

    DEFF Research Database (Denmark)

    Song, Quanfeng; Zhang, Wenqi; Bay, Niels

    2005-01-01

    Electrical contact resistance is of critical importance in resistance welding. In this article, the contact resistance is experimentally investigated for welding mild steel, stainless steel, and aluminum to themselves. A parametric study was carried out on a Gleeble® machine, investigating...

  8. Cytokines and mother sporocysts in susceptible and resistant Bulinus truncatus snails infected with Schistosoma haematobium.

    Science.gov (United States)

    El-Din, Abdel Hakim Saad; Gawish, Fathiya Ali; Abu El Einin, Hanaa Mohamed; Mansour, Shereen Mahfouz

    2014-08-01

    The presence of immunoreactive interleukin (IL-2), interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) in addition to the citation of mother sporscytes in cephalopodal musculature in the susceptible and resistance Bulinus truncatus the specific intermediate host for the trematode Schistosoma haematobium were investigated,. Using ELISA tests, Results indicated that the concentration of IL-2-like activity in the susceptible and resistant snails decreased significantly after infection then persisted at low levels until the 4th week post exposure (WPE) in susceptible snails, while in resistant snails elevated during the second WPE, and returned to initial level at 3 and 4 WPE. Susceptible snails had low detectable levels of TNF-α and INF-γ like-activity after infection. However, the resistant snails had significant low levels of TNF-α and INF-γ like-activity from 3 WPE until the 4th WPE without any sign of normalization. Histological sections in the head- foot region of susceptible and resistance B. truncatus infected with S. haematobium, mother sporocysts exists from 1 to 7(day post exposure) DPE, in the susceptible snail the mother sporocysts were found as single, multiple and mature types. No mother sporocysts were appear in the lip and mantle of the snail on 2, 5, 7 DPE and on 1-3, 6 DPE respectively. In the resistant snails few mother sporocysts were found in the lip, mantle and tentacles. The results showed that schistosome-resistant Bulinus can be an alternative strategy for the control of schistosomiasis.

  9. Antimicrobial susceptibility and presence of resistance genes in staphylococci from poultry

    DEFF Research Database (Denmark)

    Aarestrup, Frank Møller; Agersø, Yvonne; Ahrens, Peter

    2000-01-01

    The species distribution, susceptibility to 19 antimicrobial agents and presence of selected genes encoding resistance to macrolides, streptogramins and tetracyclines were examined among 118 staphylococcal isolates from infections of poultry in Denmark. Isolates were identified using a combination...... of conventional biochemical testing and 16S rDNA sequencing. The most common species were Staphylococcus aureus (83), Staphylococcus hyicus (11), Staphylococcus xylosus (9) and Staphylococcus cohnii (6). The isolates were susceptible to most antimicrobials tested. A high frequency of S. aureus (30%) was resistant...... to ciprofloxacin. Only six (7%) S. aureus isolates and one Staphylococcus saprophyticus were penicillin resistant. Resistance to sulphamethoxazole was observed among 16 (19%) of S. aureus isolates and two coagulase negative staphylococci (CNS). Twenty (24%) of the S. aureus isolates were resistant to erythromycin...

  10. Differential protein expression in the susceptible and resistant Myzus persicae (Sulzer) to imidacloprid.

    Science.gov (United States)

    Meng, JianYu; Zhang, ChangYu; Chen, XingJiang; Cao, Yi; Shang, ShengHua

    2014-10-01

    Myzus persicae, a serious economic agricultural pest, has developed resistance to imidacloprid (IMI), which was widely used to control this aphid worldwide. To gain a better understanding of the mechanisms of IMI resistance in M. persicae, we carried out a comparative proteomic analysis. Total proteins of the IMI-susceptible and resistant strains were extracted and separated by two-dimensional gel electrophoresis. More than 1300 protein spots were reproducibly detected, including 14 that were more abundant and 14 less abundant. Mass spectrometry analysis and database searching helped us to identify 25 differentially abundant proteins. The identified proteins were categorized into several functional groups including signal transduction, RNA processing, protein processing, transport processing, stress response, metabolisms, and cytoskeleton structure, etc. This study is the first analysis of differentially expressed proteins in IMI-susceptible and resistant M. Persicae, and gives new insights into the mechanisms of IMI resistance in M. persicae. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Collateral damage: rapid exposure-induced evolution of pesticide resistance leads to increased susceptibility to parasites.

    Science.gov (United States)

    Jansen, Mieke; Stoks, Robby; Coors, Anja; van Doorslaer, Wendy; de Meester, Luc

    2011-09-01

    Although natural populations may evolve resistance to anthropogenic stressors such as pollutants, this evolved resistance may carry costs. Using an experimental evolution approach, we exposed different Daphnia magna populations in outdoor containers to the carbamate pesticide carbaryl and control conditions, and assessed the resulting populations for both their resistance to carbaryl as well as their susceptibility to infection by the widespread bacterial microparasite Pasteuria ramosa. Our results show that carbaryl selection led to rapid evolution of carbaryl resistance with seemingly no cost when assessed in a benign environment. However, carbaryl-resistant populations were more susceptible to parasite infection than control populations. Exposure to both stressors reveals a synergistic effect on sterilization rate by P. ramosa, but this synergism did not evolve under pesticide selection. Assessing costs of rapid adaptive evolution to anthropogenic stress in a semi-natural context may be crucial to avoid too optimistic predictions for the fitness of the evolving populations. © 2011 The Author(s).

  12. Vertical electrical resistivity investigation of foundation conditions ...

    African Journals Online (AJOL)

    Four Vertical Electrical Soundings have been carried out for building sites using Schlumberger array within a buried River channel near Okilton close, Port Harcourt. The objective was to delineate the different geoelectric and geologic parameters of the subsurface as a means of determining its effect on foundation.

  13. Environmental Sciences Electrical resistivity soundings to determine ...

    African Journals Online (AJOL)

    Four Wenner apparent pseudosections and a vertical electrical sounding were made at the Orita Aperin refuse dump site, Ibadan, South West Nigeria, to map the gross layered structure of the refuse as well as the extent of groundwater contamination. Wood, leaves, newspaper, cloth, polythene bags, plastics, glass and ...

  14. Susceptibility to insecticides and resistance mechanisms in Aedes aegypti from the Colombian Caribbean Region.

    Science.gov (United States)

    Maestre-Serrano, Ronald; Gomez-Camargo, Doris; Ponce-Garcia, Gustavo; Flores, Adriana E

    2014-11-01

    We determined the susceptibility to insecticides and the biochemical and molecular mechanisms involved in resistance in nine populations of Aedes aegypti (L.) of the Colombian Caribbean region. Bioassays were performed on larvae for susceptibility to temephos and on adults to the insecticides malathion, fenitrothion, pirimiphos-methyl, permethrin, deltamethrin, λ-cyhalothrin and cyfluthrin. The resistance ratio (RR) for each insecticide in the populations was determined, using the susceptible Rockefeller strain as a susceptible control. Additionally, we evaluated the response of the populations to the diagnostic dose (DD) of the organochlorine pesticide DDT. The following biochemical mechanisms associated with resistance were studied: α-esterases, β-esterases, mixed-function oxidases (MFO), glutathione s-transferases (GST) and insensitive acetylcholinesterase (iAChE) as well as the presence of kdr I1,016 mutation and its frequency. All populations studied showed susceptibility to the organophosphates evaluated (RR Soledad populations which showed high resistance (RR 15-fold) and moderate resistance (RR 5-fold) to temephos, respectively, and Sincelejo (Sucre) with moderate resistance to pirimiphos-methyl (RR 5-fold). All populations evaluated with DD of DDT were found to be resistant with 2-28% of mortality. Variability was observed in the resistance to pyrethroids: permethrin (RR 1.2- to 30.8-fold), deltamethrin RR 0.9- to 37.8-fold), λ-cyalothrin (RR 3.4- to 83-fold) and cyfluthrin (RR 0.3- to 33.8-fold). Incipiently α-esterases and MFO levels were found in the Valledupar population; MFO showed the same profile in Cienaga and GST in the Sincelejo population, all other populations showed unaltered profiles of the enzymes evaluated. The kdr I1,016 mutation was found in all populations evaluated with variability in its allelic and genotypic frequencies. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Susceptibility of some multiple resistant bacteria to garlic extract

    African Journals Online (AJOL)

    GREGO

    2007-03-19

    Mar 19, 2007 ... cold with headache, fever and sore throat. Garlic extracts are also known to be effective against Helicobacter pylori, the cause of gastric ..... Antimicrob. Agents 12: 257-262. Klein JO (1999). Management of acute otitis media in an era of increasing antibiotic resistance, Int. J. Pediatric Otorhinolaringology,.

  16. Multidrug‑resistant acinetobacter infection and their susceptibility ...

    African Journals Online (AJOL)

    Background: Antibiotic‑resistant Acinetobacter nosocomial infection is a leading problem. It acts as an opportunistic pathogen to cause a wide spectrum of infection including nosocomial pneumonia, meningitis, endocarditis, skin and soft tissue infections, urinary tract infection, conjunctivitis, burn wound infection and ...

  17. Influence of electrical resistivity and machining parameters on electrical discharge machining performance of engineering ceramics.

    Directory of Open Access Journals (Sweden)

    Renjie Ji

    Full Text Available Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR, electrode wear ratio (EWR, and surface roughness (SR. The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical

  18. Influence of electrical resistivity and machining parameters on electrical discharge machining performance of engineering ceramics.

    Science.gov (United States)

    Ji, Renjie; Liu, Yonghong; Diao, Ruiqiang; Xu, Chenchen; Li, Xiaopeng; Cai, Baoping; Zhang, Yanzhen

    2014-01-01

    Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge

  19. Antimicrobial resistance in methicillin susceptible and methicillin resistant Staphylococcus pseudintermedius of canine origin: literature review from 1980 to 2013.

    Science.gov (United States)

    Moodley, Arshnee; Damborg, Peter; Nielsen, Søren Saxmose

    2014-07-16

    Staphylococcus pseudintermedius is a commensal and a common opportunistic pathogen causing mainly infections of the integumentary system in dogs. The recent emergence of multidrug-resistant S. pseudintermedius isolates, in particular methicillin-resistant strains (MRSP) is a threat to small animal health and highlights the need for antimicrobial resistance surveillance to detect trends and potentially perform timeous interventions. We systematically reviewed 202 published articles to investigate temporal changes in antimicrobial resistance in clinical and commensal S. pseudintermedius isolated from dogs in 27 countries between 1980 and 2013. Resistance to the most common antimicrobials tested for in published studies and important for the treatment of staphylococcal infections in dogs were assessed separately for methicillin resistant (MRSP) and methicillin susceptible (MSSP) isolates. Stratified by MSSP and MRSP, no significant increases in antimicrobial resistance were observed over time, except for the penicillinase-labile penicillins (penicillin and ampicillin) among MSSP. However, in recent years, a few studies have reported higher-level of resistance to amikacin, gentamicin and enrofloxacin amongst MSSP. The review highlights inconsistencies between studies as a result of several factors, for example the use of different antimicrobial susceptibility testing methods and interpretation criteria. We recommend that data on susceptibility in important companion animal pathogens are collected and presented in a more harmonized way to allow more precise comparison of susceptibility patterns between studies. One way to accomplish this would be through systematic surveillance either at the country-level or at a larger scale across countries e.g. EU level. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Measure of tissue resistivity in experimental electrical burns.

    Science.gov (United States)

    Chilbert, M; Maiman, D; Sances, A; Myklebust, J; Prieto, T E; Swiontek, T; Heckman, M; Pintar, K

    1985-03-01

    Studies were conducted in 14 mongrel dogs to compare resistivities in normal muscle with those from muscle subjected to electrical burns. One-ampere, 60-Hz currents were passed between the hind limbs of the dogs producing injury in three measurement regions of the gracilis muscle. Histology, heart rate, body temperature, arterial and pulmonary artery pressure, cardiac output, hematocrit, leukocyte counts, fibrinogen levels, and platelet levels were determined. Muscle resistivity associated with severe tissue necrosis was 70% lower than control values. Resistivity in tissue showing edema and minimal necrosis decreased 20 to 40% from control values. Muscle showing only edema had a 10 to 30% decrease in resistivity.

  1. Monitoring of Leachate Recirculation in a Bioreactor Using Electrical Resistivity

    Science.gov (United States)

    Grellier, S.; Bureau, N.; Robain, H.; Tabbagh, A.; Camerlynck, C.; Guerin, R.

    2004-05-01

    The bioreactor is a concept of waste landfill management consisting in speeding up the biodegradation by optimizing the moisture content through leachate recirculation. Electrical resistivity tomography (ERT) is carried out with fast resistivity-meter (Syscal Pro, IRIS Instruments, developed in the framework of the research project CERBERE 01V0665-69, funded by the French Research Ministry) to monitor leachate recirculation. During a recirculation period waste moisture increases, so that electrical resistivity may decrease, but at the same time temperature and mineralization of both waste and leachate become intermixed. If waste temperature is much higher than leachate temperature electrical resistivity will not decrease as much as if the temperature difference was smaller. If leachate mineralization (i.e. leachate conductivity) is higher than that of wet waste in the landfill, electrical resistivity will tend to decrease. Otherwise for example after an addition of rain water into the leachate storage or in case of very wet waste, the resistivities of each medium (leachate and wet waste) can be almost the same, so that leachate mineralization will not have a great influence on waste resistivity. Resistivity measurements were performed during 85 minutes injection trials (with a discharge of 20 m3 h-1) where leachate was injected through a vertical borehole perforated between 1.85 and 4.15 m. Three first measurements are made during the injection (3, 30 and 60 minutes from the beginning of the injection) and the two other after the injection period (8 and 72 minutes after the end of the injection). Apparent and interpreted resistivity variations that occurred during injection trials, expressed as the relative differences (in %) between apparent, respectively interpreted, resistivity during injection and apparent, respectively interpreted, resistivity before injection (reference measurement) show the formation of a plume (a negative anomaly: resistivity decreases with

  2. Susceptibility and resistance to insecticides of Chagas disease vectors.

    Science.gov (United States)

    Zerba, E N

    1999-01-01

    Chemical control of Chagas disease vectors appears to be the best practical way to reduce the incidence of the disease. DDT was initially tested in the 1950s for the campaigns of control of Chagas disease vectors. Its low level of effectiveness against triatomine caused the failure of these control actions. HCH was then introduced in the southern cone and Dieldrin in the north of Latinoamerica. Starting in the late 1960s anticholinesterasic organophosphorus and carbamate compounds were introduced in the control of Chagas vectors. The use of pyrethroid compounds began in 1980. This family of insecticides is now the most important tool in triatomines control because of its favorable toxicological properties. Other types of insecticides also studied for Chagas vector control were the insect growth regulators and the antifeeding compounds. Because of the mode of action of these insecticides they are now considered just a potential complement of neurotoxic insecticides for integrated programmes of Triatomines control. Innovative formulations such as fumigant canister and insecticidal paints have been successfully developed in Latinoamerica with the World Health Organization support. Resistance to insecticides of triatomines is not yet a great problem in Chagas vectors. However, some resistant strains to pyrethroids have been found in Rhodnius prolixus from Venezuela and in Triatoma infestans from Brazil. Some cases of T. infestans incipient resistance to deltamethrin have been detected in Argentina. According to the control tools now available it is possible to expect the interruption of vector transmission of Chagas disease in the near future.

  3. Field susceptibility of 13 scab-resistant apple cultivars to apple powdery mildew [Podosphaera leucotricha (Ell. et Ev. Salmon

    Directory of Open Access Journals (Sweden)

    Zbigniew Borecki

    2013-12-01

    Full Text Available Field susceptibility of 13 scab-resistant apple cultivars to apple powdery mildew was evaluated in 1983-1986. Four groups of susceptibility were distinguished. None of the 13 tested scab-resistant apple trees exhibited complete field immunity to apple powdery mildew. Two cultivars, 'Prima' and 'Primula', were practically resistant. 'Liberty' and two numbered selections, NY-140-9 and NY-158-2, belonged to the group of lower susceptibility. Moderate susceptibility was shown by: 'Novamac', 'Freedom', 'Gavin', 'Prima' and 'Florina'. The group of apple trees most susceptible to Podosphaera leucotricha included: 'Macfree', 'Priscilla' and 'Nova Easygro'. It is not necessary to use chemical sprays to control powdery mildew on 'Prima' and 'Primula'. A reduced spraying program may be recommended only under high disease pressure on less susceptible apple cultivars. A regular spray schedule is needed on moderately susceptible apple trees, but improved chemical control is necessary on the most susceptible ones.

  4. Population Susceptibility to Insecticides and the Development of Resistance in Bactrocera cucurbitae (Diptera: Tephritidae).

    Science.gov (United States)

    Jin, Tao; Lin, Yu-Ying; Jin, Qi-An; Wen, Hai-Bo; Peng, Zheng-Qiang

    2016-04-01

    Excessive insecticide applications are commonly used to manage Bactrocera cucurbitae Coquillett in China. Resistance status, resistance development trends, and patterns of cross-resistance to insecticides in B. cucurbitae were investigated. Among 21 populations from Hainan Island, two populations expressed high resistance to beta-cypermethrin; seven, eight, and ten populations expressed intermediate resistance to spinosad, avermectin, and beta-cypermethrin, respectively; four, six, one, five, and four populations expressed low resistance to spinosad, avermectin, trichlorfon, beta-cypermethrin, and fipronil, respectively; and the remaining populations exhibited either minor resistance or remained susceptible. Analysis of the development of resistance showed that resistance levels to spinosad and avermectin were readily developed at 40.68- and 18.42-fold, respectively, and a spinosad-resistant strain also showed relative positive cross-resistance to beta-cypermethrin and avermectin, but relative negative cross-resistance to trichlorfon and fipronil. These data represent the most extensive survey of insecticide resistance conducted in B. cucurbitae to date, and the level of insecticide resistance in populations should be considered when designing control measures and pest management strategies.

  5. Cross-resistance and baseline susceptibility of spirotetramat in Frankliniella occidentalis (Thysanoptera: Thripidae).

    Science.gov (United States)

    Guillén, Juan; Navarro, Miguel; Bielza, Pablo

    2014-06-01

    Western flower thrips, Frankliniella occidentalis (Pergande), is an economically important pest all over the world. New products against thrips are necessary, as there are few effective compounds exhibiting cross-resistance among them. Lethal effects, cross-resistance, and baseline susceptibility to spirotetramat were evaluated in this study. A new bioassay method for testing thrips against spirotetramat was developed. Spirotetramat showed a significant mortality effect on larvae after 7 d of exposure, but a low effect was observed on adults. Baseline results for larval instars showed LC50 values ranging from 11.59 to 49.81 mg AI/liter, with a low natural variability (3.2-fold). Cross-resistance studies showed overlapping confidence limits of the LC50 values for laboratory-selected (against acrinathrin, methiocarb, formetanate, and spinosad) resistant and susceptible strains, and low resistance factors, from 0.5 to 1.9, suggesting no cross-resistance to conventional insecticides previously used. A slight ovicidal effect (21-40% reduction) was also detected. Despite presenting low effects on adults, spirotetramat showed high but slow efficacy on F. occidentalis larvae. Field populations in southeast Spain showed a consistent susceptibility to spirotetramat. Given the scarcity of effective products and the lack of cross-resistance to other insecticides, spirotetramat can be considered as a good chemical tool to control F. occidentalis.

  6. Defense response of susceptible and resistant Biomphalaria alexandrina snails against Schistosoma mansoni infection

    Directory of Open Access Journals (Sweden)

    Iman F. Abou-El-Naga

    2012-09-01

    Full Text Available In Egypt, Biomphalaria alexandrina is the intermediate host for Schistosoma mansoni. The fates of Schistosoma miracidia in the snails varies between different species of Biomphalaria. The internal defense system is one of the factors that influence the susceptibility pattern of the snails. The interaction between Biomphalaria snails and S. mansoni needs to be identified for each species, and even between the members of the same species with different degrees of susceptibility. In the present study, the first generation of susceptible and resistant parents of B. alexandrina was examined histologically at the 30th day post exposure. The study includes the characterization of the immune response, as expressed by tissue reactions, of susceptible and resistant B. alexandrina snails against S. mansoni. It was also designed to determine the impact of the resistance increase in parent snails, on the mechanisms of interaction of their offspring against infection. The results showed that the infection rate of the offspring from the susceptible parents was 92%. No susceptible offspring was produced from the resistant parents. When the parents were of equal number of susceptible and resistant snails, they gave an offspring with an infection rate of 20%. Susceptible snails that had susceptible parents showed a higher degree of susceptibility than those that had both susceptible and resistant parents. A common feature of the resistant snails was the absence of any viable parasites. The tissue reactions of the resistant snails having only resistant parents occurred at the site of miracidial penetration. In resistant snails for which susceptible ones were included in their parents, the reactions occurred in the deep tissues. These results characterized the immune response of B. alexandrina snails against Schistosoma infection which was found to occur by two different mechanisms. One type of defense occurs in highly resistant snails, and employs direct

  7. Resistance noise in electrically biased bilayer graphene.

    Science.gov (United States)

    Pal, Atindra Nath; Ghosh, Arindam

    2009-03-27

    We demonstrate that the low-frequency resistance fluctuations, or noise, in bilayer graphene are strongly connected to its band structure and display a minimum when the gap between the conduction and valence band is zero. Using double-gated bilayer graphene devices we have tuned the zero gap and charge neutrality points independently, which offers a versatile mechanism to investigate the low-energy band structure, charge localization, and screening properties of bilayer graphene.

  8. Groundwater potential evaluation using electrical resistivity method ...

    African Journals Online (AJOL)

    ... anisotropy of between 1.18 and 1.88. This weathered to a mixture of clay and sand with low to medium groundwater yield; Mica-schist with aquifer resistivity in the range of 16 – 40m and coefficient of anisotropy of between 1.3 and 2.3. This weathered into more of clay because of its high ferromagnetic mineral content and ...

  9. Application of electrical resistivity survey for groundwater ...

    African Journals Online (AJOL)

    A geo-resistivity exploration has been carried out for groundwater within the Akobo catchment of the ancient city of Ibadan. The area lies within the basement rock terrain of South Western Nigeria and bounded by longitudes 3o 51′ – 3o 53′E and latitudes 7o 22′ – 7o 24′N. The exploration was done using SYSCAL ...

  10. Ampicillin-resistant Haemophilus influenzae isolates in Geneva: serotype, antimicrobial susceptibility, and β-lactam resistance mechanisms.

    Science.gov (United States)

    Cherkaoui, A; Diene, S M; Emonet, S; Renzi, G; Francois, P; Schrenzel, J

    2015-10-01

    The purpose of this study was to analyze the molecular mechanisms of ampicillin-resistant Haemophilus influenzae isolated in Geneva, Switzerland. We investigated the association between specific patterns of amino acid substitutions in penicillin-binding protein 3 (with or without β-lactamase production) and β-lactam susceptibility. Another main focus for this study was to compare the accuracy of disk diffusion and Etest methods to detect resistance to ampicillin and amoxicillin/clavulanic acid. The antibiotic susceptibility to β-lactam antibiotics of 124 H. influenzae isolates was determined by disk diffusion and Etest methods, and interpreted by European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) breakpoints. Alterations in PBP3 were investigated by sequencing the ftsI gene. Of the 124 clinical isolates analyzed, ampicillin resistance was found in 36% (45 out of 124). The rate of resistance to amoxicillin/clavulanic acid was 9% and 0.8%, using EUCAST and CLSI breakpoints respectively. For the 78 β-lactamase negative ampicillin-susceptible (BLNAS) isolates for which the Etest method indicated a high degree of susceptibility (MIC ≤ 1 mg/L), the disk diffusion method revealed resistance to ampicillin and amoxicillin/clavulanic acid in 33 cases (42%). Most common amino acid substitutions were Asn526Lys and Val547Ile, followed by Asp569Ser, Ala502Val, Asp350Asn, Met377Ile, Ile449Val, and Arg517His. The patterns observed were classified into six groups (IIa, IIb, IIc, IId, III-like, and miscellaneous). Continued characterization of both invasive and respiratory H. influenzae isolates is necessary in order to observe changes in the microbiology and epidemiology of this pathogen that could lead to clinical failure when treated by empirical antibiotic therapy.

  11. Using electrical resistance tomography to map subsurface temperatures

    Science.gov (United States)

    Ramirez, Abelardo L.; Chesnut, Dwayne A.; Daily, William D.

    1994-01-01

    A method is provided for measuring subsurface soil or rock temperatures remotely using electrical resistivity tomography (ERT). Electrical resistivity measurements are made using electrodes implanted in boreholes driven into the soil and/or at the ground surface. The measurements are repeated as some process changes the temperatures of the soil mass/rock mass. Tomographs of electrical resistivity are calculated based on the measurements using Poisson's equation. Changes in the soil/rock resistivity can be related to changes in soil/rock temperatures when: (1) the electrical conductivity of the fluid trapped in the soil's pore space is low, (2) the soil/rock has a high cation exchange capacity and (3) the temperature changes are sufficiently high. When these three conditions exist the resistivity changes observed in the ERT tomographs can be directly attributed to changes in soil/rock temperatures. This method provides a way of mapping temperature changes in subsurface soils remotely. Distances over which the ERT method can be used to monitor changes in soil temperature range from tens to hundreds of meters from the electrode locations.

  12. Fluoxetine Hydrochloride Enhances In Vitro Susceptibility to Chloroquine in Resistant Plasmodium falciparum

    Science.gov (United States)

    1992-12-01

    directed synthesis of new antimalarial drugs. Malaria is a significant source of morbidity in the world, ity, desipramine (3) and chlorpromazine (12... Hydrochloride Enhances In Vitro Susceptibility to Chloroguine in Resistant Plasmodium falciparum 4. AUTHOR(S) Lucia Gerena, Glenn T. Bass, Sr., Dennis E. Kyle...current description of the chloroquine resistance phenotype and may provide additional insights into lead-directed synthesis of new antimalarial drugs

  13. Dynamic metabolic responses of brown planthoppers towards susceptible and resistant rice plants

    OpenAIRE

    Liu, Caixiang; Du, Ba; Hao, Fuhua; Lei, Hehua; Wan, Qianfen; He, Guangcun; Wang, Yulan; Tang, Huiru

    2017-01-01

    Summary Brown planthopper (Nilaparvata lugens Stål, BPH) causes huge economic losses in rice‐growing regions, and new strategies for combating BPH are required. To understand how BPHs respond towards BPH‐resistant plants, we systematically analysed the metabolic differences between BPHs feeding on the resistant and susceptible plants using NMR and GC‐FID/MS. We also measured the expression of some related genes involving glycolysis and biosyntheses of trehalose, amino acids, chitin and fatty ...

  14. Chemical probes for drug-resistance assessment by binding competition (RABC): oseltamivir susceptibility evaluation.

    Science.gov (United States)

    Cheng, Ting-Jen R; Wang, Shi-Yun; Wen, Wen-Hsien; Su, Ching-Yao; Lin, Mengi; Huang, Wen-I; Liu, Ming-Tsan; Wu, Ho-Sheng; Wang, Nung-Sen; Cheng, Chung-Kai; Chen, Chun-Lin; Ren, Chien-Tai; Wu, Chung-Yi; Fang, Jim-Min; Cheng, Yih-Shyun E; Wong, Chi-Huey

    2013-01-02

    The wizard of OS (resistance): the binding difference of neuraminidase inhibitors (zanamivir versus oseltamivir (OS)) was used to establish an assay to identify the influenza subtypes that are resistant to OS but still sensitive to zanamivir. This assay used a zanamivir-biotin conjugate to determine the OS susceptibility of a wide range of influenza viruses and over 200 clinical isolates. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Emergence of decreased susceptibility and resistance to extended-spectrum cephalosporins in Neisseria gonorrhoeae in Korea.

    Science.gov (United States)

    Lee, Hyukmin; Unemo, Magnus; Kim, Hyo Jin; Seo, Younghee; Lee, Kyungwon; Chong, Yunsop

    2015-09-01

    Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major concern globally; however, no comprehensive AMR data for gonococcal isolates cultured after 2006 in Korea have been published internationally. We determined the susceptibility of N. gonorrhoeae isolates cultured in 2011-13, the mechanism of extended-spectrum cephalosporin (ESC) resistance and the molecular epidemiology of gonococcal strains in Korea. In 2011-13, 210 gonococcal isolates were collected in Korea and their AMR profiles were examined by the agar dilution method. The penA, mtrR, penB, ponA and pilQ genes were sequenced in 25 isolates that were resistant to ESCs and 70 randomly selected isolates stratified by year. For molecular epidemiology, N. gonorrhoeae multiantigen sequence typing and MLST were performed. None of the N. gonorrhoeae isolates was susceptible to penicillin G and most were resistant to tetracycline (50%) and ciprofloxacin (97%). The rates of resistance to ceftriaxone, azithromycin, cefpodoxime and cefixime were 3%, 5%, 8% and 9%, respectively. However, all isolates were susceptible to spectinomycin. Twenty-one (84%) of the 25 ESC-resistant isolates contained the non-mosaic PBP2 XIII allele; however, the remaining 4 (16%) possessed the mosaic PBP2 X allele, which has been previously associated with ESC resistance including treatment failures. In Korea, susceptibility to spectinomycin remains high. However, the recent emergence of ESC-resistant N. gonorrhoeae strains, including strains possessing the PBP2 mosaic X and non-mosaic XIII alleles, is a major concern and enhanced AMR surveillance is necessary to prevent transmission of these strains. © The Author 2015. 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.

  16. Specific adjustments in grapevine leaf proteome discriminating resistant and susceptible grapevine genotypes to Plasmopara viticola.

    Science.gov (United States)

    Figueiredo, Andreia; Martins, Joana; Sebastiana, Mónica; Guerreiro, Ana; Silva, Anabela; Matos, Ana Rita; Monteiro, Filipa; Pais, Maria Salomé; Roepstorff, Peter; Coelho, Ana Varela

    2017-01-30

    Grapevine downy mildew is an important disease affecting crop production leading to severe yield losses. This study aims to identify the grapevine cultivar-specific adjustments of leaf proteome that allow the discrimination between resistance and susceptibility towards P. viticola (constitutive (0h) and in after inoculation (6, 12 and 24h). Leaf proteome analysis was performed using 2D difference gel electrophoresis followed by protein identification via mass spectrometry. In addition, we analysed ROS production, antioxidant capacity, lipid peroxidation and gene expression. Proteins related to photosynthesis and metabolism allowed the discrimination of resistant and susceptible grapevine cultivars prior to P. viticola inoculation. Following inoculation increase of hydrogen peroxide levels, cellular redox regulation, establishment of ROS signalling and plant cell death seem to be key points differentiating the resistant genotype. Lipid associated signalling events, particularly related to jasmonates appear also to play a major role in the establishment of resistance. The findings from this study contribute to a better understanding of genotype-specific differences that account for a successful establishment of a defence response to the downy mildew pathogen. Here, we present for the first time grapevine cultivar-specific adjustments of leaf proteome that allow the discrimination between resistance and susceptibility towards P. viticola (constitutive (0h) and in after inoculation (6, 12 and 24h). We have highlighted that, following inoculation, the major factors differentiating the resistant from the susceptible grapevine cultivars are the establishment of effective ROS signalling together with lipid-associated signalling events, particularly related to jasmonates. It is believed that plants infected with biotrophic pathogens suppress JA-mediated responses, however recent evidences shown that jasmonic acid signalling pathway in grapevine resistance against Plasmopara

  17. Impact of phenolic compounds and related enzymes in Sorghum varieties for resistance and susceptibility to biotic and abiotic stresses

    NARCIS (Netherlands)

    Dicko, M.H.; Gruppen, H.; Barro, C.; Traore, A.S.; Berkel, van W.J.H.; Voragen, A.G.J.

    2005-01-01

    Contents of phenolic compounds and related enzymes before and after sorghum grain germination were compared between varieties either resistant or susceptible to biotic (sooty stripe, sorghum midge, leaf anthracnose, striga, and grain molds) and abiotic (lodging, drought resistance, and photoperiod

  18. Insecticide susceptibility and resistance development in malathion selected Aedes albopictus (Skuse).

    Science.gov (United States)

    Selvi, S; Edah, M A; Nazni, W A; Lee, H L; Tyagi, B K; Sofian-Azirun, M; Azahari, A H

    2010-12-01

    Aedes albopictus was bioassayed to determine resistance development to malathion (OP). Two methods were applied, including WHO larval bioassay to determine the susceptibility to lethal concentration (LC), and adult bioassay to determine lethal time (LT). Larvae from colonies that had undergone selection pressure with malathion to yield 50% mortality were further subjected to selection for subsequent 10 generations. Selection of Ae. albopictus with malathion could relatively induce a consistent resistance ratio of 1.0 throughout 10 generations. It was noted that Ae. albopictus larvae showed less susceptibility to malathion compared to adults. The susceptibility test of adult mosquitoes to diagnostic dosage of 5.0% malathion-impregnated paper showed a variety of susceptibility to malathion when compared to the susceptible strain. Bioassay results indicated that the LT50 values of malathion-selected Ae. albopictus ranged between 11.5 - 58.8 minutes for ten consecutive generations. Biochemical enzyme studies indicated that there was a significant difference (p albopictus suggested that non-specific esterases do not play a role in resistance of malathion-selected Ae. albopictus.

  19. Assessment of the process of movement of Xylella fastidiosa within susceptible and resistant grape cultivars.

    Science.gov (United States)

    Baccari, C; Lindow, S E

    2011-01-01

    To better understand the processes contributing to symptoms and resistance to Pierce's disease of grape, we examined the movement and multiplication of a green fluorescent protein-marked strain of Xylella fastidiosa in the stems and petioles of Cabernet Sauvignon, Chenin Blanc, Roucaneuf, and Tampa grape cultivars that differ in their susceptibility to this disease. X. fastidiosa achieved much lower population sizes and colonized fewer xylem vessels in the stem of resistant cultivars compared with more susceptible cultivars. In contrast, X. fastidiosa achieved similarly high population sizes and colonized a similar proportion of the vessels in petioles of susceptible and resistant cultivars, suggesting that, compared with the stem, X. fastidiosa is relatively unrestricted in its movement and growth within the petiole. There was not a direct relationship between the population size of X. fastidiosa in the stem and the proportion of vessels colonized; a much higher population size of the pathogen was observed in susceptible cultivars than expected based on the proportion of vessels colonized. The high population sizes of X. fastidiosa in stems of susceptible genotypes were associated with both a high number of infected vessels and a much higher extent of colonization of those vessels that become infested than in more resistant cultivars. The formation of large cellular aggregates in vessels is not required for X. fastidiosa to move laterally in the stem to adjacent vessels because most vessels harbored only small assemblages, especially in resistant cultivars such as Roucaneuf, in which some intervessel movement was detected. Resistance to Pierce's disease is apparently not due to inhibitory compounds that circulate in the xylem because they might be expected to operate similarly in all tissues.

  20. Differentially expressed proteins in fluconazole-susceptible and fluconazole-resistant isolates of Candida glabrata.

    Science.gov (United States)

    Shen, Yinzhong; Zhang, Lijun; Jia, Xiaofang; Zhang, Yongxin; Lu, Hongzhou

    2015-06-01

    The current study aimed to identify the differences presented in the proteome of fluconazole-susceptible isolates of Candida glabrata compared to those with fluconazole-resistant ones. Two-dimensional differential gel electrophoresis was applied to identify proteins that were differentially expressed in fluconazole-susceptible and fluconazole-resistant isolates of C. glabrata. Eight proteins including aspartyl-tRNA synthetase, translation elongation factor 3, 3-phosphoglycerate kinase, ribosomal protein L5, coproporphyrinogen III oxidase, pyruvate kinase, G-beta like protein, and F1F0-ATPase alpha subunit were found to be more abundantly represented, while four proteins including vitamin B12-(cobalamin)-independent isozyme of methionine synthase, microtubule-associated protein, adenylosuccinate synthetase, and aldose reductase were found to be less abundantly represented in fluconazole-resistant strains versus those with fluconazole-susceptible ones. These differentially expressed proteins were primarily associated with energy metabolism, stress response, and macromolecule synthesis. Proteins associated with energy metabolism, stress response, and macromolecule synthesis may play a role in the development of fluconazole resistance in the clinical isolates of C. glabrata. Multiple different mechanisms are involved in the development of fluconazole resistance in C. glabrata. These findings provide a scientific basis for discovering new genes and mechanisms associated with fluconazole resistance in C. glabrata.

  1. Methicillin-resistant and methicillin-susceptible community-acquired Staphylococcus aureus infection among children

    Directory of Open Access Journals (Sweden)

    Renata Tavares Gomes

    Full Text Available Methicillin-resistant Staphylococcus aureus has emerged as a pathogen associated with community-acquired infections worldwide. We report the spectrum of community-acquired S. aureus infections and compare the patients infected with methicillin-susceptible or methicillin-resistant strains among patients aged <20 years. Overall, 90 cases of community acquired S. aureus were detected in an 11-year period. Clinical and microbiological data were registered. Fifty-nine (66% patients were male and the median age was two years. The majority (87% of the patients were hospitalized and chronic underlying illnesses were detected in 27 (30% cases. Overall, 34 (37.8% patients had skin/soft tissue infections and 56 (62.2% patients had deep-seated infection. Four (5.1% patients were transferred to the intensive care unit and two (2.6% died. Complications were detected in 17 (18.9% cases, such as pleural effusion (41.2%, osteomyelitis (23.5%, and sepsis (17.6%. Six (6.7% methicillin-resistant strains were detected. Patients infected with methicillin-susceptible or methicillin-resistant strains had similar baseline characteristics and treatment outcomes. Approximately 93% of the cases received systemic antibiotics, out of which 59 (65.5% used oxacillin or cefalotin. Both methicillin-susceptible and methicillin-resistant S. aureus strains resulted in morbidity and death among children in this setting where methicillin-resistant strains are infrequent.

  2. Comparison of cellular responses to Xanthomonas perforans infection between resistant and susceptible tomato accessions.

    Science.gov (United States)

    Wang, Y Q; Zhang, X F; Li, N; Liu, X

    2017-02-01

    Bacterial spot of tomato (Solanum lycopersicum L.) caused by several Xanthomonas species is one of the most destructive diseases. Genes regulating the hypersensitive resistance and field resistance to X. perforans race T3 have been intensively investigated over the last decade. However, a comparative analysis of cellular responses to the pathogen in susceptible and resistant hosts has not been completed, which prevents the detailed understanding of the interactions between the pathogen and tomato plants. In this study, the characteristics of lesions, stomata, and pathogen colonization in hypersensitive response (HR) PI 128216, field-resistant PI 114490, and susceptible OH 88119 tomato plants after inoculation with green fluorescent protein-labeled X. perforans race T3 bacteria were investigated. Significant differences in developmental processes and the micromorphology of spot lesions among three tomato lines were observed. Our results suggested that the faster lesion development in OH 88119 plants compared with that of the other two lines was associated with a greater increase in the stomatal apertures over a longer period following bacterial inoculation. The depth of bacterial colonization and pathogen density inside infected leaves in OH 88119 were also significantly different from that of resistant tomato plants. Determination of the ultrastructural responses to X. perforans among three tomato lines revealed that cell wall defense response was the main difference between resistant and susceptible tomato lines. These results may provide fundamental information for understanding the cellular and molecular mechanisms regulating tomato responses to X. perforans race T3. Copyright © 2016 Elsevier GmbH. All rights reserved.

  3. Cardiovascular Disease Susceptibility and Resistance in Circumpolar Inuit Populations.

    Science.gov (United States)

    Tvermosegaard, Maria; Dahl-Petersen, Inger K; Nielsen, Nina Odgaard; Bjerregaard, Peter; Jørgensen, Marit Eika

    2015-09-01

    Cardiovascular disease (CVD) is a major public health issue in indigenous populations in the Arctic. These diseases have emerged concomitantly with profound social changes over the past 60 years. The aim of this study was to summarize the literature on CVD risk among Arctic Inuit. Literature on prevalence, incidence, and time trends for CVD and its risk factors in Arctic Inuit populations was reviewed. Most evidence supports a similar incidence of coronary heart disease and a higher incidence of cerebrovascular disease among Arctic Inuit than seen in western populations. Factors that may increase CVD risk include aging of the population, genetic susceptibility, and a rapid increase in obesity, diabetes, and hypertension in parallel with decreasing physical activity and deterioration of the lipid profile. In contrast, and of great importance, there has been a decrease in smoking and alcohol intake (at least documented in Greenland), and contaminant levels are declining. Although there have been marked socioeconomic and dietary changes, it remains unsolved and to some extent controversial how this may have influenced cardiovascular risk among Arctic Inuit. The increase in life expectancy, in combination with improved prognosis for patients with manifest CVD, will inevitably lead to a large increase in absolute numbers of individuals affected by CVD in Arctic Inuit populations, exacerbated by the rise in most CVD risk factors over the past decades. For preventive purposes and for health care planning, it is crucial to carefully monitor disease incidence and trends in risk factors in these vulnerable Arctic populations. Copyright © 2015 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  4. Growth and reproduction of triazine-susceptible and -resistant Solanum nigrum in a maize crop.

    NARCIS (Netherlands)

    Kremer, E.; Kropff, M.J.

    1998-01-01

    Growth and berry production of triazine-susceptible and -resistant Solanum nigrum L. in the field with and without a maize crop were studied over 3 years. Delayed transplanting reduced the final dry matter production and berry production greatly. In most of the experiments, the final total dry

  5. Azithromycin Resistance and Decreased Ceftriaxone Susceptibility in Neisseria gonorrhoeae, Hawaii, USA.

    Science.gov (United States)

    Papp, John R; Abrams, A Jeanine; Nash, Evelyn; Katz, Alan R; Kirkcaldy, Robert D; O'Connor, Norman P; O'Brien, Pamela S; Harauchi, Derek H; Maningas, Eloisa V; Soge, Olusegun O; Kersh, Ellen N; Komeya, Alan; Tomas, Juval E; Wasserman, Glenn M; Kunimoto, Gail Y; Trees, David L; Whelen, A Christian

    2017-05-01

    During 2016, eight Neisseria gonorrhoeae isolates from 7 patients in Hawaii were resistant to azithromycin; 5 had decreased in vitro susceptibility to ceftriaxone. Genomic analysis demonstrated a distinct phylogenetic clade when compared with local contemporary strains. Continued evolution and widespread transmission of these strains might challenge the effectiveness of current therapeutic options.

  6. Antimicrobial Susceptibility Breakpoints and First-Step parC Mutations in Streptococcus pneumoniae: Redefining Fluoroquinolone Resistance

    OpenAIRE

    Lim, Sue; Bast, Darrin; McGeer, Allison; de Azavedo, Joyce; Low, Donald E.

    2003-01-01

    Clinical antimicrobial susceptibility breakpoints are used to predict the clinical outcome of antimicrobial treatment. In contrast, microbiologic breakpoints are used to identify isolates that may be categorized as susceptible when applying clinical breakpoints but harbor resistance mechanisms that result in their reduced susceptibility to the agent being tested. Currently, the National Committee for Clinical Laboratory Standards (NCCLS) guidelines utilize clinical breakpoints to characterize...

  7. Phenotypic characterization and colistin susceptibilities of carbapenem-resistant of Pseudomonas aeruginosa and Acinetobacter spp.

    Science.gov (United States)

    Mohanty, Srujana; Maurya, Vijeta; Gaind, Rajni; Deb, Monorama

    2013-11-15

    Pseudomonas aeruginosa and Acinetobcter spp. are important nosocomial pathogens and carbapenem resistance is an emerging threat. Therapeutic options for infections with these isolates include colistin. This study was conducted to determine the prevalence of carbapenem resistance in P. aeruginosa and Acinetobacter spp. bloodstream isolates, phenotypically characterize the resistance mechanisms and evaluate the in vitro activity of colistin. Consecutive 145 (95 P.aeruginosa and 50 Acinetobacter spp.) non-repeat isolates were included. Antibiotic susceptibility testing was performed per CLSI guidelines. MIC for carbapenems and colistin was performed using Etest. Isolates showing reduced susceptibility or resistance to the carbapenems were tested for metallo-β-lactamase (MBL) production using imipenem-EDTA combined disk and MBL Etest. Carbapenem resistance was observed in 40% P. aeruginosa and 66.0% Acinetobacter spp. Carbapenem-resistant (CA-R) isolates were significantly (p aeruginosa and Acinetobacter spp., respectively. Colistin resistance was observed in three (6.0%) Acinetobacter isolates and eight (8.4%) P. aeruginosa. MIC50 for carbapenems were two to four times higher for MBL-positive compared to MBL-negative isolates, but no difference was seen in MIC for colistin. Carbapenem resistance was observed to be mediated by MBL in a considerable number of isolates. Colistin is an alternative for infections caused by CA-R isolates; however, MIC testing should be performed whenever clinical use of colistin is considered.

  8. Transcriptome and Small RNAome Dynamics during a Resistant and Susceptible Interaction between Cucumber and Downy Mildew

    Directory of Open Access Journals (Sweden)

    Alyssa Burkhardt

    2016-03-01

    Full Text Available Cucumber ( L. downy mildew, caused by the obligate oomycete pathogen (Berk. and Curt. Rostov., is the primary factor limiting cucumber production. Although sources of resistance have been identified, such as plant introduction line PI 197088, the genes and processes involved in mediating resistance are still unknown. In the current study, we conducted a comprehensive transcriptome and small RNAome analysis of a resistant (PI 197088 and susceptible (‘Vlaspik’ cucumber during a time course of infection using Illumina sequencing. We identified significantly differentially expressed (DE genes within and between resistant and susceptible cucumber leaves over a time course of infection. Weighted gene correlation network analyses (WGCNA created coexpression modules containing genes with unique expression patterns between Vlaspik and PI 197088. Recurring data trends indicated that resistance to cucumber downy mildew is associated with earlier response to the pathogen, hormone signaling, and regulation of nutrient supply. Candidate resistance genes were identified from multiple transcriptome analyses and literature support. Additionally, parallel sequencing of small RNAs (sRNAs from cucumber and during the infection time course was used to identify and quantify novel and existing microRNA (miRNA in both species. Predicted miRNA targets of cucumber transcripts suggest a complex interconnectedness of gene expression regulation in this plant–pathogen system. This work bioinformatically uncovered gene expression patterns involved in the mediation of or response to resistance. Herein, we provide the foundation for future work to validate candidate resistance genes and miRNA-based regulation proposed in this study.

  9. Antimicrobial susceptibility testing for Helicobacter pylori in times of increasing antibiotic resistance.

    Science.gov (United States)

    Smith, Sinéad M; O'Morain, Colm; McNamara, Deirdre

    2014-08-07

    The gram-negative bacterium Helicobacter pylori (H. pylori) causes chronic gastritis, gastric and duodenal ulcers, gastric cancer and mucosa-associated lymphoid tissue lymphoma. Treatment is recommended in all symptomatic patients. The current treatment options for H. pylori infection are outlined in this review in light of the recent challenges in eradication success, largely due to the rapid emergence of antibiotic resistant strains of H. pylori. Antibiotic resistance is a constantly evolving process and numerous studies have shown that the prevalence of H. pylori antibiotic resistance varies significantly from country to country, and even between regions within the same country. In addition, recent data has shown that previous antibiotic use is associated with harbouring antibiotic resistant H. pylori. Local surveillance of antibiotic resistance is warranted to guide clinicians in their choice of therapy. Antimicrobial resistance is assessed by H. pylori culture and antimicrobial susceptibility testing. Recently developed molecular tests offer an attractive alternative to culture and allow for the rapid molecular genetic identification of H. pylori and resistance-associated mutations directly from biopsy samples or bacterial culture material. Accumulating evidence indicates that surveillance of antimicrobial resistance by susceptibility testing is feasible and necessary to inform clinicians in their choice of therapy for management of H. pylori infection.

  10. Electrical resistivity of thin metal films

    CERN Document Server

    Wissmann, Peter

    2007-01-01

    The aim of the book is to give an actual survey on the resistivity of thin metal and semiconductor films interacting with gases. We discuss the influence of the substrate material and the annealing treatment of the films, presenting our experimental data as well as theoretical models to calculate the scattering cross section of the conduction electrons in the frame-work of the scattering hypothesis. Main emphasis is laid on the comparison of gold and silver films which exhibit nearly the same lattice structure but differ in their chemical activity. In conclusion, the most important quantity for the interpretation is the surface charging z while the correlation with the optical data or the frustrated IR vibrations seems the show a more material-specific character. Z can be calculated on the basis of the density functional formalism or the self-consistent field approximation using Mulliken’s population analysis.

  11. Polymyxins: Antibacterial Activity, Susceptibility Testing, and Resistance Mechanisms Encoded by Plasmids or Chromosomes.

    Science.gov (United States)

    Poirel, Laurent; Jayol, Aurélie; Nordmann, Patrice

    2017-04-01

    SUMMARYPolymyxins are well-established antibiotics that have recently regained significant interest as a consequence of the increasing incidence of infections due to multidrug-resistant Gram-negative bacteria. Colistin and polymyxin B are being seriously reconsidered as last-resort antibiotics in many areas where multidrug resistance is observed in clinical medicine. In parallel, the heavy use of polymyxins in veterinary medicine is currently being reconsidered due to increased reports of polymyxin-resistant bacteria. Susceptibility testing is challenging with polymyxins, and currently available techniques are presented here. Genotypic and phenotypic methods that provide relevant information for diagnostic laboratories are presented. This review also presents recent works in relation to recently identified mechanisms of polymyxin resistance, including chromosomally encoded resistance traits as well as the recently identified plasmid-encoded polymyxin resistance determinant MCR-1. Epidemiological features summarizing the current knowledge in that field are presented. Copyright © 2017 American Society for Microbiology.

  12. Electrical resistivity testing for as-built concrete performance assessment of chloride penetration resistance

    NARCIS (Netherlands)

    Polder, R.B.; Peelen, W.H.A.

    2014-01-01

    The electrical resistivity of concrete can provide information about its transport properties, which is relevant for durability performance. For example, resistivity is inversely proportional to chloride diffusion, at least within similar concrete compositions. A methodology is proposed for on-site

  13. Electron–electron interactions and the electrical resistivity of lithium ...

    Indian Academy of Sciences (India)

    The contribution of the electron–electron Umklapp scattering processes in the electrical resistivity of lithium at low temperatures has been evaluated using a simplified ... Department of Physics, Regional Institute of Education, National Council of Educational Research & Training, Shyamla Hills, Bhopal 462 013, India ...

  14. Superconductivity and electrical resistivity in alkali metal doped ...

    Indian Academy of Sciences (India)

    Unknown

    Superconductivity and electrical resistivity in alkali metal doped fullerides: Phonon mechanism. DINESH VARSHNEY*, A DUBE, K K CHOUDHARY† and R K SINGH. ‡. School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore 452 017, India. †Department of Physics, SVITS, Indore 453 ...

  15. The role of Intelectin-2 in resistance to Ascaris suum lung larval burdens in susceptible and resistant mouse strains.

    Science.gov (United States)

    Dold, Christina; Pemberton, Alan D; Stafford, Peter; Holland, Celia V; Behnke, Jerzy M

    2011-04-01

    The underlying mechanism of predisposition to Ascaris infection is not yet understood but host genetics are thought to play a fundamental role. We investigated the association between the Intelectin-2 gene and resistance in F2 mice derived from mouse strains known to be susceptible and resistant to infection. Ascaris larvae were isolated from murine lungs and the number of copies of the Intelectin-2 gene was determined in F2 mice. Intelectin-2 gene copy number was not significantly linked to larval burden. In a pilot experiment, the response to infection in parental mice of both sexes was observed in order to address the suitability of female F2 mice. No overall significant sex effect was detected. However, a divergence in resistance/susceptibility status was observed between male and, female hybrid offspring. The responsiveness to Ascaris in mice is likely to be controlled by multiple genes and, despite a unique absence from the susceptible C57BL/6j strain, the Intelectin-2 gene does not play a significant role in resistance. The observed intra-strain variation in larval burden requires further investigation but we hypothesize that it stems from social/dominance hierarchies created by the presence of female mice and possibly subsequent hormonal perturbations that modify the intensity of the immune response.

  16. Implications of the simultaneous presence of metronidazole-susceptible and -resistant Helicobacter pylori colonies within a single biopsy specimen

    NARCIS (Netherlands)

    Arents, NLA; Smeets, LC; van Zwet, AA; Thijs, JC; van der Wouden, EJ; Degener, JE; Kusters, JG; de Jong, A.

    This study examined whether the simultaneous presence of metronidazole-susceptible and -resistant Helicobacter pylori colonies in a single biopsy specimen is caused by a multiple strain infection with a susceptible and a resistant strain or by two subpopulations within a single strain. Single

  17. Comparison of protein profiles of beech bark disease-resistant or beech bark disease-susceptible American beech

    Science.gov (United States)

    Mary E. Mason; Marek Krasowski; Judy Loo; Jennifer. Koch

    2011-01-01

    Proteomic analysis of beech bark proteins from trees resistant and susceptible to beech bark disease (BBD) was conducted. Sixteen trees from eight geographically isolated stands, 10 resistant (healthy) and 6 susceptible (diseased/infested) trees, were studied. The genetic complexity of the sample unit, the sampling across a wide geographic area, and the complexity of...

  18. The Electrical Resistance of Rutherford-Type Superconducting Cable Splices

    CERN Document Server

    Heck, C; Fleiter, J; Bottura, L

    2015-01-01

    The electrical resistance of Large Hadron Collider main busbar cable lap splices produced by soft soldering has been measured with two independent methods as a function of intercable contact area and for splices made of cables with various defects. For defect-free lap splices, the resistance increases from 0.3 to 10 nΩ (at 4.3 K in self-field) when reducing the cable overlap length from 120 to 3 mm, as expected assuming that the resistance is inversely proportional to the intercable contact area. The resistance of bridge splices that connect side-by-side cables can be predicted from the lap splice resistances and the overlap areas involved.

  19. Electric Crosstalk Effect in Valence Change Resistive Random Access Memory

    Science.gov (United States)

    Sun, Jing; Wang, Hong; Wu, Shiwei; Song, Fang; Wang, Zhan; Gao, Haixia; Ma, Xiaohua

    2017-08-01

    Electric crosstalk phenomenon in valence change resistive switching memory (VCM) is systematically investigated. When a voltage is applied on the VCM device, an electric field is formed in the isolated region between the devices, which causes the oxygen vacancies in conductive filaments (CFs) to drift apart, leading to a consequent resistance degradation of the neighboring devices. The effects of distance between memory cells, electrodes widths and physical dimensions of CFs on the memory performance are investigated in this work. Furthermore, the strategies to mitigate electric crosstalk effects are developed. According to the simulation results, the crosstalk phenomenon can become more severe as the distance between memory cells or the electrode width decreases. In order to optimize the device performance, it is helpful to control the location of the break points of CFs in the device close to the top electrode. Alternatively, taking the integration density into account, switching materials with a small field accelerated parameter can also contribute to obtaining a stable performance.

  20. Red rot resistant gene characterization using RGAP markers among sugarcane cultivars resistant and susceptible to the red rot disease.

    Science.gov (United States)

    Sharma, Ruchika; Tamta, Sushma

    2017-10-01

    Sugarcane is the major source of sugar in Asia and Europe, grown primarily in the tropical and sub-tropical zones of the world. The main disease responsible for its low yield is red rot. Therefore, in the present study, characterization of red rot disease was performed among 55 different sugarcane cultivars varying in red rot resistance level. 18 fragments were found to be associated with red rot resistance and were identified as resistant specific markers. The resistant specific fragments were amplified by RGA169, RGA396, RGA129, RGA231, RGA251, RGA057, RGA118, RGA152, RGA327, RGA542, RGA012, RGA173, RGA184, RGA275, RGA019, RGA267, RGA281 and RGA533. 7 fragments were found to be associated with red rot susceptibility and were considered as susceptible specific markers amplified by RGA088, RGA162, RGA396, RGA231, RGA251, RGA087 and RGA275. Sequencing of five resistant fragments, viz., RGA169, RGA231, RGA251, RGA267 and RGA533 was performed and the data thus obtained showed 80-99% similarity when compared with other resistant gene sequences previously submitted in NCBI database.

  1. Image-guided inversion of electrical resistivity data

    Science.gov (United States)

    Zhou, J.; Revil, A.; Karaoulis, M.; Hale, D.; Doetsch, J.; Cuttler, S.

    2014-04-01

    Electrical resistivity tomography (ERT) is based on solving a Poisson equation for the electrical potential and is characterized by a good sensitivity only in the vicinity of the electrodes used to gather the data. To provide more information to ERT, we propose an image-guided or structure-constrained inversion of the apparent resistivity data. This approach uses structural information obtained directly from a guiding image. This guiding image can be drawn from a high resolution geophysical method based on the propagation equation (e.g. migrated seismic or ground penetrating radar images) or possibly from a geological cross-section of the subsurface based on some prior geological expertise. The locations and orientations of the structural features can be extracted by image processing methods to determine the structure tensor and the semblances of the guiding image at a set of pixel. Then, we introduce these structural constraints into the inversion of the apparent resistivity data by weighting the four-direction smoothing matrix to smooth along, but not across, structural features. This approach allows preserving both discontinuities and coherences in the inversion of the resistivity data. The image-guided inversion is also combined with an image-guided interpolation approach used to focus a smooth resistivity image. This yields structurally-appealing resistivity tomograms, while the whole process remains computationally efficient. Such a procedure generates a more realistic resistivity distribution (closer to the true ones), which can be, in turn, used quantitatively using appropriate petrophysical transforms, to obtain parameters of interest such as porosity and saturation. We check the validity of this approach using two synthetic case studies as well as two real datasets. For the field data, the image used to guide the inversion of the electrical resistivity data is a GPR section in the first case and a combination of seismic and structural information in the

  2. Genetic diversity within and among two-spotted spider mite resistant and susceptible common bean genotypes

    Directory of Open Access Journals (Sweden)

    Zeinab YOUSEFI

    2017-12-01

    Full Text Available Two-spotted spider mite (Tetranychus urticae C. L. Koch, 1836, is one of the most destructive herbivores of common bean. Very little is known about the diversity among resistant sources in this crop. The present study was conducted to characterize 22 resistant and susceptible common bean genotypes by 8 Simple Sequence Repeats (SSRs and 8 Random Amplified Polymorphic DNA (RAPD markers. These SSR and RAPD primers produced 100 % and 81.8 % polymorphic bands. Based on RAPD fingerprints and SSR profiles, pairwise genetic similarity ranged from 0.0 to 0.857 and from 0.125 to 1, respectively. The resistant and susceptible common bean accessions were grouped together in the dendrograms generated from RAPD and SSR clustering analyses. The results indicate that RAPD and SSR analysis could be successfully used for the estimation of genetic diversity among genotypes. SSR markers could group genotypes according to their resistibility and susceptibility to the spotted spider mite but RAPD could not. Therefore, the SSR markers can facilitate the development of resistant common bean cultivars through breeding programs against T. urticae.

  3. Are there clinical variables determining antibiotic prophylaxis-susceptible versus resistant infection in open fractures?

    Science.gov (United States)

    Gonzalez, Amanda; Suvà, Domizio; Dunkel, Nathalie; Nicodème, Jean-Damien; Lomessy, Antoine; Lauper, Nicolas; Rohner, Peter; Hoffmeyer, Pierre; Uçkay, Ilker

    2014-11-01

    In Gustilo grade III open fractures, it remains unknown which demographic or clinical features may be associated with an infection resistant to the administered prophylactic agent, compared to one that is susceptible. This was a retrospective case-control study on patients hospitalized from 2004 to 2009. We identified 310 patients with Gustilo-III open fractures, 36 (12%) of which became infected after a median of ten days. In 26 (72%) of the episodes the pathogen was susceptible to the prophylactic antibiotic agent prescribed upon admission, while in the other ten it was resistant. All antibiotic prophylaxis was intravenous; the median duration of treatment was three days and the median delay between trauma and surgery was one day. In multivariate analysis adjusting for case-mix, only Gustilo-grade-IIIc fractures (vascular lesions) showed tendency to be infected with resistant pathogens (odds ratio 10; 95% confidence interval 1.0-10; p = 0.058). There were no significant differences between cases caused by antibiotic resistant and susceptible pathogen cases in patient's sex, presence of immune suppression, duration and choice of antibiotic prophylaxis, choice of surgical technique or materials, time delay until surgery, use of bone reaming, fracture localization, or presence of compartment syndrome. We were unable to identify any specific clinical parameters associated with infection with antibiotic resistant pathogens in Gustilo-grade III open fractures, other than the severity of the fracture itself. More research is needed to identify patients who might benefit from a broader-spectrum antibiotic prophylaxis.

  4. Evaluation of the pyrrole insecticide chlorfenapyr against pyrethroid resistant and susceptible Anopheles funestus (Diptera: Culicidae).

    Science.gov (United States)

    Oliver, S V; Kaiser, M L; Wood, O R; Coetzee, M; Rowland, M; Brooke, B D

    2010-01-01

    To evaluate the pyrrole insecticide chlorfenapyr, which has a novel non-neurotoxic mode of action and is a promising alternative to conventional adulticides, against Anopheles funestus. The toxicity of a range of concentrations of chlorfenapyr against pyrethroid resistant and susceptible laboratory reared southern African An. funestus was assessed using standard WHO protocols and analysed using probit analysis. The pyrethroid resistant strain showed consistently higher LD50 and LD95 values compared to the susceptible strain, but these differences were not statistically significant and the magnitude was twofold at most. The LD50 values recorded for An. funestus are approximately three-fold higher than those reported elsewhere for other species of anopheline. Monooxygenase based pyrethroid resistance in An. funestus does not influence the toxic effect of chlorfenapyr. It is unlikely that such a small decrease in susceptibility of An. funestus to chlorfenapyr relative to other anophelines would have any operational implications. Chlorfenapyr is an important addition to insecticides available for malaria vector control, and could be used as a resistance management tool to either circumvent or slow the development of resistance.

  5. [Drug resistance mutations and susceptibility phenotypes of Neisseria gonorrhoeae isolates in Russia].

    Science.gov (United States)

    Kubanov, A A; Leinsoo, A T; Chestkov, A V; Dementieva, E I; Shaskolskiy, B L; Solomka, V S; Gryadunov, D A; Deryabin, D G

    2017-01-01

    Steady growth in the degree of antimicrobial resistance in Neisseria gonorrhoeae calls for the control of the spreading of resistance mutations. Here we present the data describing drug resistance mutations, the results of antimicrobial susceptibility tests, and molecular genotypes of 128 recent N. gonorrhoeae isolates collected across 9 regions of the Russian Federation. The mutations in chromosome genes penA, ponA, rpsJ, gyrA, parC, which determine the susceptibility of N. gonorrhoeae to penicillins, tetracyclines, and fluoroquinolones were detected by multiplex amplification followed by hybridization on a hydrogel microarray. The most frequent mutation was an insertion of an aspartate at position 345 of penA gene (76.6%), whereas mutations Leu421Pro in ponA gene, Val57Met in rpsJ gene, Ser91Phe in gyrA gene, Asp95Gly in gyrA gene, and Ser87Arg in parC gene were detected in 32.8-36.7% of strains. One third of studied N. gonorrhoeae isolates harbored multiple drug resistance mutations in bacterial chromosome, resulting in the bimodal distribution of mutation profiles and related patterns of antimicrobial susceptibility. The spread of multiple resistance could be explained by the vertical transfer of the mutations resulting in the clonality of the N. gonorrhoeae population.

  6. Selection, resistance risk assessment, and reversion toward susceptibility of pyriproxyfen in Musca domestica L.

    Science.gov (United States)

    Shah, Rizwan Mustafa; Abbas, Naeem; Shad, Sarfraz Ali; Sial, Ashfaq Ahmad

    2015-02-01

    Pyriproxyfen, a juvenile hormone mimic, is an effective larvicide against many pests of veterinary and public health importance. Pyriproxyfen is a biorational insecticide having many environmentally friendly attributes that make it compatible with integrated pest management programs. This experiment was performed for the assessment of resistance evolution and reversion toward susceptibility of Musca domestica to pyriproxyfen. Repeated selection at successive generations resulted in 5.09- and 130-fold increase in lethal concentration 50 (LC50) compared to field and susceptible strain, respectively. A significant decline after 22 generations without selection suggesting resistance to pyriproxyfen was unstable in M. domestica. Realized heritability (h (2)) of resistance to pyriproxyfen was 0.035 in pyriproxyfen-selected strain of M. domestica. The projected rate of resistance development indicated that, if slope = 1.28 and h (2) = 0.035, then 46-21 generations are required for 10-fold increase in LC50 at 50-90 % selection intensity. These findings suggest that a risk for resistance development to pyriproxyfen occurred in M. domestica under continuous selection pressure. Pyriproxyfen susceptibility reversed when its application is ceased for a specified duration.

  7. Gene Expression Analysis of Plum pox virus (Sharka Susceptibility/Resistance in Apricot (Prunus armeniaca L..

    Directory of Open Access Journals (Sweden)

    Manuel Rubio

    Full Text Available RNA-Seq has proven to be a very powerful tool in the analysis of the Plum pox virus (PPV, sharka disease/Prunus interaction. This technique is an important complementary tool to other means of studying genomics. In this work an analysis of gene expression of resistance/susceptibility to PPV in apricot is performed. RNA-Seq has been applied to analyse the gene expression changes induced by PPV infection in leaves from two full-sib apricot genotypes, "Rojo Pasión" and "Z506-7", resistant and susceptible to PPV, respectively. Transcriptomic analyses revealed the existence of more than 2,000 genes related to the pathogen response and resistance to PPV in apricot. These results showed that the response to infection by the virus in the susceptible genotype is associated with an induction of genes involved in pathogen resistance such as the allene oxide synthase, S-adenosylmethionine synthetase 2 and the major MLP-like protein 423. Over-expression of the Dicer protein 2a may indicate the suppression of a gene silencing mechanism of the plant by PPV HCPro and P1 PPV proteins. On the other hand, there were 164 genes involved in resistance mechanisms that have been identified in apricot, 49 of which are located in the PPVres region (scaffold 1 positions from 8,050,804 to 8,244,925, which is responsible for PPV resistance in apricot. Among these genes in apricot there are several MATH domain-containing genes, although other genes inside (Pleiotropic drug resistance 9 gene or outside (CAP, Cysteine-rich secretory proteins, Antigen 5 and Pathogenesis-related 1 protein; and LEA, Late embryogenesis abundant protein PPVres region could also be involved in the resistance.

  8. Gene Expression Analysis of Plum pox virus (Sharka) Susceptibility/Resistance in Apricot (Prunus armeniaca L.).

    Science.gov (United States)

    Rubio, Manuel; Ballester, Ana Rosa; Olivares, Pedro Manuel; Castro de Moura, Manuel; Dicenta, Federico; Martínez-Gómez, Pedro

    2015-01-01

    RNA-Seq has proven to be a very powerful tool in the analysis of the Plum pox virus (PPV, sharka disease)/Prunus interaction. This technique is an important complementary tool to other means of studying genomics. In this work an analysis of gene expression of resistance/susceptibility to PPV in apricot is performed. RNA-Seq has been applied to analyse the gene expression changes induced by PPV infection in leaves from two full-sib apricot genotypes, "Rojo Pasión" and "Z506-7", resistant and susceptible to PPV, respectively. Transcriptomic analyses revealed the existence of more than 2,000 genes related to the pathogen response and resistance to PPV in apricot. These results showed that the response to infection by the virus in the susceptible genotype is associated with an induction of genes involved in pathogen resistance such as the allene oxide synthase, S-adenosylmethionine synthetase 2 and the major MLP-like protein 423. Over-expression of the Dicer protein 2a may indicate the suppression of a gene silencing mechanism of the plant by PPV HCPro and P1 PPV proteins. On the other hand, there were 164 genes involved in resistance mechanisms that have been identified in apricot, 49 of which are located in the PPVres region (scaffold 1 positions from 8,050,804 to 8,244,925), which is responsible for PPV resistance in apricot. Among these genes in apricot there are several MATH domain-containing genes, although other genes inside (Pleiotropic drug resistance 9 gene) or outside (CAP, Cysteine-rich secretory proteins, Antigen 5 and Pathogenesis-related 1 protein; and LEA, Late embryogenesis abundant protein) PPVres region could also be involved in the resistance.

  9. Establishment of Stable, Cell-Mediated Immunity that Makes "Susceptible" Mice Resistant to Leishmania major

    Science.gov (United States)

    Bretscher, Peter A.; Wei, Guojian; Menon, Juthika N.; Bielefeldt-Ohmann, Helle

    1992-07-01

    Cell-mediated, but not antibody-mediated, immune responses protect humans against certain pathogens that produce chronic diseases such as leishmaniasis. Effective vaccination against such pathogens must therefore produce an immunological "imprint" so that stable, cell-mediated immunity is induced in all individuals after natural infection. BALB/c mice "innately susceptible" to Leishmania major produce antibodies after substantial infection. In the present study, "susceptible" mice injected with a small number of parasites mounted a cell-mediated response and acquired resistance to a larger, normally pathogenic, challenge. This vaccination strategy may be applicable in diseases in which protection is dependent on cell-mediated immunity.

  10. Electrical carotid sinus stimulation in treatment resistant arterial hypertension.

    Science.gov (United States)

    Jordan, Jens; Heusser, Karsten; Brinkmann, Julia; Tank, Jens

    2012-12-24

    Treatment resistant arterial hypertension is commonly defined as blood pressure that remains above goal in spite of the concurrent use of three antihypertensive agents of different classes. The sympathetic nervous system promotes arterial hypertension and cardiovascular as well as renal damage, thus, providing a logical treatment target in these patients. Recent physiological studies suggest that baroreflex mechanisms contribute to long-term control of sympathetic activity and blood pressure providing an impetus for the development of electrical carotid sinus stimulators. The concept behind electrical stimulation of baroreceptors or baroreflex afferent nerves is that the stimulus is sensed by the brain as blood pressure increase. Then, baroreflex efferent structures are adjusted to counteract the perceived blood pressure increase. Electrical stimulators directly activating afferent baroreflex nerves were developed years earlier but failed for technical reasons. Recently, a novel implantable device was developed that produces an electrical field stimulation of the carotid sinus wall. Carefully conducted experiments in dogs provided important insight in mechanisms mediating the depressor response to electrical carotid sinus stimulation. Moreover, these studies showed that the treatment success may depend on the underlying pathophysiology of the hypertension. Clinical studies suggest that electrical carotid sinus stimulation attenuates sympathetic activation of vasculature, heart, and kidney while augmenting cardiac vagal regulation, thus lowering blood pressure. Yet, not all patients respond to treatment. Additional clinical trials are required. Patients equipped with an electrical carotid sinus stimulator provide a unique opportunity gaining insight in human baroreflex physiology. Copyright © 2012. Published by Elsevier B.V.

  11. Forensic Assessment on Ground Instability Using Electrical Resistivity Imaging (ERI)

    Science.gov (United States)

    Hazreek, Z. A. M.; Azhar, A. T. S.; Aziman, M.; Fauzan, S. M. S. A.; Ikhwan, J. M.; Aishah, M. A. N.

    2017-02-01

    Electrical resistivity imaging (ERI) was used to evaluate the ground settlement in local scale at housing areas. ERI and Borehole results were used to interpret the condition of the problematic subsurface profile due to its differential stiffness. Electrical resistivity of the subsurface profile was measured using ABEM SAS4000 equipment set. ERI results using electrical resistivity anomaly on subsurface materials resistivity shows the subsurface profile exhibited low (1 - 100 Ωm) and medium (> 100 Ωm) value (ERV) representing weak to firm materials. The occurrences of soft to medium cohesive material (SPT N value = 2 - 7) and stiff cohesive material (SPT N ≥ 8) in local scale has created inconsistency of the ground stability condition. Moreover, it was found that a layer of organic decayed wood (ERV = 43 ˜ 29 Ωm & SPT N = 15 ˜ 9) has been buried within the subsurface profile thus weaken the ground structure and finally promoting to the ground settlement. The heterogeneous of the subsurface material presented using integrated analysis of ERI and borehole data enabled ground settlement in this area to be evaluated. This is the major factor evaluating ground instability in the local scale. The result was applicable to assist in planning a strategy for sustainable ground improvement of local scale in fast, low cost, and large data coverage.

  12. Recent Advances in Electrical Resistance Preheating of Aluminum Reduction Cells

    Science.gov (United States)

    Ali, Mohamed Mahmoud; Kvande, Halvor

    2017-02-01

    There are two mainpreheating methods that are used nowadays for aluminum reduction cells. One is based on electrical resistance preheating with a thin bed of small coke and/or graphite particles between the anodes and the cathode carbon blocks. The other is flame preheating, where two or more gas or oil burners are used. Electrical resistance preheating is the oldest method, but is still frequently used by different aluminum producers. Many improvements have been made to this method by different companies over the last decade. In this paper, important points pertaining to the preparation and preheating of these cells, as well as measurements made during the preheating process and evaluation of the performance of the preheating, are illustrated. The preheating times of these cells were found to be between 36 h and 96 h for cell currents between 176 kA and 406 kA, while the resistance bed thickness was between 13 mm and 60 mm. The average cathode surface temperature at the end of the preheating was usually between 800°C and 950°C. The effect of the preheating methods on cell life is unclear and no quantifiable conclusions can be drawn. Some works carried out in the mathematical modeling area are also discussed. It is concluded that there is a need for more studies with real situations for preheated cells on the basis of actual measurements. The expected development in electrical resistance preheating of aluminum reduction cells is also summarized.

  13. Scenario Evaluator for Electrical Resistivity survey pre-modeling tool

    Science.gov (United States)

    Terry, Neil; Day-Lewis, Frederick D.; Robinson, Judith L.; Slater, Lee D.; Halford, Keith J.; Binley, Andrew; Lane, John W.; Werkema, Dale

    2017-01-01

    Geophysical tools have much to offer users in environmental, water resource, and geotechnical fields; however, techniques such as electrical resistivity imaging (ERI) are often oversold and/or overinterpreted due to a lack of understanding of the limitations of the techniques, such as the appropriate depth intervals or resolution of the methods. The relationship between ERI data and resistivity is nonlinear; therefore, these limitations depend on site conditions and survey design and are best assessed through forward and inverse modeling exercises prior to field investigations. In this approach, proposed field surveys are first numerically simulated given the expected electrical properties of the site, and the resulting hypothetical data are then analyzed using inverse models. Performing ERI forward/inverse modeling, however, requires substantial expertise and can take many hours to implement. We present a new spreadsheet-based tool, the Scenario Evaluator for Electrical Resistivity (SEER), which features a graphical user interface that allows users to manipulate a resistivity model and instantly view how that model would likely be interpreted by an ERI survey. The SEER tool is intended for use by those who wish to determine the value of including ERI to achieve project goals, and is designed to have broad utility in industry, teaching, and research.

  14. Arabidopsis thaliana resistance to fusarium oxysporum 2 implicates tyrosine-sulfated peptide signaling in susceptibility and resistance to root infection.

    Directory of Open Access Journals (Sweden)

    Yunping Shen

    2013-05-01

    Full Text Available In the plant Arabidopsis thaliana, multiple quantitative trait loci (QTLs, including RFO2, account for the strong resistance of accession Columbia-0 (Col-0 and relative susceptibility of Taynuilt-0 (Ty-0 to the vascular wilt fungus Fusarium oxysporum forma specialis matthioli. We find that RFO2 corresponds to diversity in receptor-like protein (RLP genes. In Col-0, there is a tandem pair of RLP genes: RFO2/At1g17250 confers resistance while RLP2 does not. In Ty-0, the highly diverged RFO2 locus has one RLP gene conferring weaker resistance. While the endogenous RFO2 makes a modest contribution to resistance, transgenic RFO2 provides strong pathogen-specific resistance. The extracellular leucine-rich repeats (eLRRs in RFO2 and RLP2 are interchangeable for resistance and remarkably similar to eLRRs in the receptor-like kinase PSY1R, which perceives tyrosine-sulfated peptide PSY1. Reduced infection in psy1r and mutants of related phytosulfokine (PSK receptor genes PSKR1 and PSKR2 shows that tyrosine-sulfated peptide signaling promotes susceptibility. The related eLRRs in RFO2 and PSY1R are not interchangeable; and expression of the RLP nPcR, in which eLRRs in RFO2 are replaced with eLRRs in PSY1R, results in constitutive resistance. Counterintuitively, PSY1 signaling suppresses nPcR because psy1r nPcR is lethal. The fact that PSK signaling does not similarly affect nPcR argues that PSY1 signaling directly downregulates the expression of nPcR. Our results support a speculative but intriguing model to explain RFO2's role in resistance. We propose that F. oxysporum produces an effector that inhibits the normal negative feedback regulation of PSY1R, which stabilizes PSY1 signaling and induces susceptibility. However, RFO2, acting as a decoy receptor for PSY1R, is also stabilized by the effector and instead induces host immunity. Overall, the quantitative resistance of RFO2 is reminiscent of the better-studied monogenic resistance traits.

  15. Inflammatory responses to induced infectious endometritis in mares resistant or susceptible to persistent endometritis

    Directory of Open Access Journals (Sweden)

    Christoffersen Mette

    2012-03-01

    Full Text Available Abstract Background The objective of the study was to evaluate the gene expression of inflammatory cytokines (interleukin [IL]-1β, IL-6, IL-8, IL-10, tumor necrosis factor [TNF]-α, IL-1 receptor antagonist [ra] and serum amyloid A (SAA in endometrial tissue and circulating leukocytes in response to uterine inoculation of 105 colony forming units (CFU Escherichia coli in mares. Before inoculation, mares were classified as resistant or susceptible to persistent endometritis based on their uterine inflammatory response to infusion of 109 killed spermatozoa and histological assessment of the endometrial quality. Endometrial biopsies were obtained 3, 12, 24 and 72 hours (h after bacterial inoculation and blood samples were obtained during the 7 day period post bacterial inoculation. Expression levels of cytokines and SAA were determined by quantitative real-time reverse transcriptase PCR (qRT-PCR. Results Compared to levels in a control biopsy (obtained in the subsequent estrous, resistant mares showed an up-regulation of IL-1β, IL-6, IL-8 and TNF-α at 3 h after E. coli inoculation, while susceptible mares showed increased gene expression of IL-6 and IL-1ra. Susceptible mares had a significant lower gene expression of TNF-α,IL-6 and increased expression of IL-1ra 3 h after E. coli inoculation compared to resistant mares. Susceptible mares showed a sustained and prolonged inflammatory response with increased gene expression levels of IL-1β, IL-8, IL-1ra and IL-1β:IL-1ra ratio throughout the entire study period (72 h, whereas levels in resistant mares returned to estrous control levels by 12 hours. Endometrial mRNA transcripts of IL-1β and IL-1ra were significantly higher in mares with heavy uterine bacterial growth compared to mares with no/mild growth. All blood parameters were unaffected by intrauterine E. coli infusion, except for a lower gene expression of IL-10 at 168 h and an increased expression of IL-1ra at 48 h observed in susceptible

  16. Cytokines produced by susceptible and resistant mice in the course of Paracoccidioides brasiliensis infection

    Directory of Open Access Journals (Sweden)

    Calich V.L.G.

    1998-01-01

    Full Text Available Paracoccidioidomycosis (PCM is the most prevalent deep mycosis in Latin America and presents a wide spectrum of clinical manifestations. We established a genetically controlled murine model of PCM, where A/Sn mice develop an infection which mimics the benign disease (immune responses which favor cellular immunity and B10.A animals present the progressive disseminated form of PCM (preferential activation of B cells and impairment of cellular immune responses. To understand the immunoregulatory phenomena associated with resistance and susceptibility in experimental PCM, A/Sn and B10.A mice were studied regarding antigen-elicited secretion of monokines (TNF-a and TGF-ß and type-1 (IL-2 and IFN-g and type-2 (IL-4,5,10 cytokines. Total lymph node cells from resistant mice infected ip with P. brasiliensis produced early and sustained levels of IFN-g and IL-2; type-2 cytokines (IL-4 and IL-5 started to appear 8 weeks after infection. In contrast, susceptible mice produced low levels of IFN-g concomitant with significant levels of IL-5 and IL-10 early in the infection. In the chronic phase of the disease, susceptible animals presented a transitory secretion of IL-2, and IL-4. In the pulmonary infection IL-4, IL-5 and IL-10 were preferentially detected in the lung cells washings of susceptible animals. After in vitro challenge with fungal antigens, normal peritoneal macrophages from B10.A mice secreted high levels of TGF-ß and low levels of TNF-a. In contrast, macrophages from A/Sn animals released high levels of TNF-a associated with a small production of TGF-ß. The in vivo depletion of IFN-g not only abrogated the resistance of A/Sn mice but also diminished the relative resistance of B10.A animals. The in vivo depletion of IL-4 did not alter the disease outcome, whereas administration of rIL-12 significantly enhanced resistance in susceptible animals. Taken together, these results suggest that an early secretion of high levels of TNF-a and IFN

  17. Toxoplasma gondii: susceptibility and development of resistance to anticoccidial drugs in vitro.

    Science.gov (United States)

    Ricketts, A P; Pfefferkorn, E R

    1993-01-01

    Anticoccidial drugs were evaluated for activity and for the development of resistance in a model of Toxoplasma gondii growing in human fibroblast cultures. Of 13 anticoccidial drugs tested, 9 had selective antitoxoplasma activity (50% inhibitory concentration, in micrograms per milliliter): decoquinate (0.005), arprinocid-N-oxide (0.015), robenidine (0.03), the aryl triazine CP-25,415 (0.2), toltrazuril (0.4), clopidol (1), dinitolmide (Zoalene; Dow) (10), and the carboxylic acid ionophores monensin (0.001) and salinomycin (0.04). Glycarbylamide, amprolium, nicarbazin, and the 6-(p-bromophenoxy)-7-chloro analog of halofuginone (Stenorol; Roussel-UCLAF) (CP-63,567) were toxic for the fibroblasts. Since Eimeria tenella has a similar drug susceptibility profile, anticoccidial durgs can be viewed as a potential source of new antitoxoplasma therapies. The development of resistance has limited the usefulness of most of these drugs as anticoccidial agents; in coccidia, resistance to all except the ionophores occurs readily in vivo. We explored the development of resistance in T. gondii by attempting to select mutants in vitro from parasites mutagenized with ethylnitrosourea. Mutants that had 20- to 50-fold-reduced susceptibility to decoquinate, arprinocid-N-oxide, and CP-25,415 were obtained. Ionophore-resistant T. gondii mutants were also selected in vitro; however, there was only a twofold difference in susceptibility between these mutants and the wild type. For three drugs (clopidol, robenidine, and toltrazuril), we were unable to select resistant mutants. For experimental anticoccidial drugs, there is currently no in vitro method for assessing the risk of development of resistance in Eimeria species. Our results suggest that T. gondii may offer a useful surrogate for this assessment. PMID:8285619

  18. Antimicrobial Susceptibility of Bordetella bronchiseptica Isolates from Swine and Companion Animals and Detection of Resistance Genes.

    Directory of Open Access Journals (Sweden)

    Sandra Prüller

    Full Text Available Bordetella bronchiseptica causes infections of the respiratory tract in swine and other mammals and is a precursor for secondary infections with Pasteurella multocida. Treatment of B. bronchiseptica infections is conducted primarily with antimicrobial agents. Therefore it is essential to get an overview of the susceptibility status of these bacteria. The aim of this study was to comparatively analyse broth microdilution susceptibility testing according to CLSI recommendations with an incubation time of 16 to 20 hours and a longer incubation time of 24 hours, as recently proposed to obtain more homogenous MICs. Susceptibility testing against a panel of 22 antimicrobial agents and two fixed combinations was performed with 107 porcine isolates from different farms and regions in Germany and 43 isolates obtained from companion animals in Germany and other European countries. Isolates with increased MICs were investigated by PCR assays for the presence of resistance genes. For ampicillin, all 107 porcine isolates were classified as resistant, whereas only a single isolate was resistant to florfenicol. All isolates obtained from companion animals showed elevated MICs for β-lactam antibiotics and demonstrated an overall low susceptibility to cephalosporines. Extension of the incubation time resulted in 1-2 dilution steps higher MIC50 values of porcine isolates for seven antimicrobial agents tested, while isolates from companion animals exhibited twofold higher MIC50/90 values only for tetracycline and cefotaxime. For three antimicrobial agents, lower MIC50 and MIC90 values were detected for both, porcine and companion animal isolates. Among the 150 isolates tested, the resistance genes blaBOR-1 (n = 147, blaOXA-2, (n = 4, strA and strB (n = 17, sul1 (n = 10, sul2 (n = 73, dfrA7 (n = 3 and tet(A (n = 8 were detected and a plasmid localisation was identified for several of the resistance genes.

  19. Remodeling of cardiac passive electrical properties and susceptibility to ventricular and atrial arrhythmias

    Directory of Open Access Journals (Sweden)

    Stefan eDhein

    2014-11-01

    Full Text Available Coordinated electrical activation of the heart is essential for the maintenance of a regular cardiac rhythm and effective contractions. Action potentials spread from one cell to the next via gap junction channels. Because of the elongated shape of cardiomyocytes, longitudinal resistivity is lower than transverse resistivity causing electrical anisotropy. Moreover, non-uniformity is created by clustering of gap junction channels at cell poles and by non-excitable structures such as collagenous strands, vessels or fibroblasts. Structural changes in cardiac disease often affect passive electrical properties by increasing non-uniformity and altering anisotropy. This disturbs normal electrical impulse propagation and is, consequently, a substrate for arrhythmia. However, to investigate how these structural changes lead to arrhythmias remains a challenge. One important mechanism, which may both cause and prevent arrhythmia, is the mismatch between current sources and sinks. Propagation of the electrical impulse requires a sufficient source of depolarizing current. In the case of a mismatch, the activated tissue (source is not able to deliver enough depolarizing current to trigger an action potential in the non-activated tissue (sink. This eventually leads to conduction block. It has been suggested that in this situation a balanced geometrical distribution of gap junctions and reduced gap junction conductance may allow successful propagation. In contrast, source-sink mismatch can prevent spontaneous arrhythmogenic activity in a small number of cells from spreading over the ventricle, especially if gap junction conductance is enhanced. Beside gap junctions, cell geometry and non-cellular structures strongly modulate arrhythmogenic mechanisms. The present review elucidates these and other implications of passive electrical properties for cardiac rhythm and arrhythmogenesis.

  20. Clinical Antibiotic-resistant Acinetobacter baumannii Strains with Higher Susceptibility to Environmental Phages than Antibiotic-sensitive Strains

    OpenAIRE

    Chen, Li-Kuang; Kuo, Shu-Chen; Chang, Kai-Chih; Cheng, Chieh-Chen; Yu, Pei-Ying; Chang, Chih-Hui; Chen, Tren-Yi; Tseng, Chun-Chieh

    2017-01-01

    Antibiotic-resistant Acinetobacter baumannii is associated with nosocomial infections worldwide. Here, we used clinically isolated A. baumannii strains as models to demonstrate whether antibiotic resistance is correlated with an increased susceptibility to bacteriophages. In this study, 24 active phages capable of infecting A. baumannii were isolated from various environments, and the susceptibilities of both antibiotic-sensitive and antibiotic-resistant strains of A. baumannii to different p...

  1. Antimicrobial susceptibility/resistance and genetic characteristics of Neisseria gonorrhoeae isolates from Poland, 2010-2012.

    Science.gov (United States)

    Mlynarczyk-Bonikowska, Beata; Serwin, Agnieszka Beata; Golparian, Daniel; Walter de Walthoffen, Szymon; Majewski, Slawomir; Koper, Marta; Malejczyk, Magdalena; Domeika, Marius; Unemo, Magnus

    2014-02-06

    In Poland, gonorrhoea has been a mandatorily reported infection since 1948, however, the reported incidences are likely underestimated. No antimicrobial resistance (AMR) data for Neisseria gonorrhoeae has been internationally reported in nearly four decades, and data concerning genetic characteristics of N. gonorrhoeae are totally lacking. The aims of this study were to investigate the AMR to previously and currently recommended gonorrhoea treatment options, the main genetic resistance determinant (penA) for extended-spectrum cephalosporins (ESCs), and genotypic distribution of N. gonorrhoeae isolates in Poland in 2010-2012. N. gonorrhoeae isolates cultured in 2010 (n = 28), 2011 (n = 92) and 2012 (n = 108) in Warsaw and Bialystok, Poland, were examined using antimicrobial susceptibility testing (Etest), pyrosequencing of penA and N. gonorrhoeae multi-antigen sequence typing (NG-MAST). The proportions of N. gonorrhoeae isolates showing resistance were as follows: ciprofloxacin 61%, tetracycline 43%, penicillin G 22%, and azithromycin 8.8%. No isolates resistant to ceftriaxone, cefixime or spectinomycin were found. However, the proportion of isolates with an ESC MIC = 0.125 mg/L, i.e. at the resistance breakpoint, increased significantly from none in 2010 to 9.3% and 19% in 2012 for ceftriaxone and cefixime, respectively. Furthermore, 3.1% of the isolates showed multidrug resistance, i.e., resistance to ciprofloxacin, penicillin G, azithromycin, and decreased susceptibility to cefixime (MIC = 0.125 mg/L). Seventy-six isolates (33%) possessed a penA mosaic allele and 14 isolates (6.1%) contained an A501V/T alteration in penicillin-binding protein 2. NG-MAST ST1407 (n = 58, 25% of isolates) was the most prevalent ST, which significantly increased from 2010 (n = 0) to 2012 (n = 46; 43%). In Poland, the diversified gonococcal population displayed a high resistance to most antimicrobials internationally previously recommended for gonorrhoea treatment and decreasing

  2. Electric-field effects in resistive oxides: facts and artifacts

    Directory of Open Access Journals (Sweden)

    Reisner G. M.

    2013-01-01

    Full Text Available Striking non-linear conductivity effects induced by surprisingly low electric-fields in charge-ordered oxides, were reported variously as dielectric breakdown, charge-order collapse, depinning of charge-density-waves or other electronic effects. Our pulsed and d.c. I-V measurements on resistive oxides show that non-linear conductivity of electronic origin at low electric-fields is a rare phenomenon. In the majority of cases we detected no deviations from linearity in pulsed I-V characteristics under fields up to E ~ 500 V/cm. Current-controlled negative-differential-resistance (NDR and hysteresis were found in d.c. measurements at fields that decrease with increasing temperatures, a behavior typical of Joule heating in materials with negative temperature coefficient of resistivity. For the d.c. I-V characteristics of our samples exhibiting NDR, we found a rather unexpected correlation between ρ(Em - the resistivity at maximum field (at the onset of NDR and ρ(E=0 – the ohmic resistivity. The data points for ρ(Em versus ρ(E=0 obtained from such characteristics of 13 samples (8 manganites, 4 nickelates and one multiferroic at various ambient temperatures, plotted together on a log-log scale, follow closely a linear dependence with slope one that spans more than five orders of magnitude. This dependence is reproduced by several simple models.

  3. Antimicrobial susceptibility of Neisseria gonorrhoeae isolates from Hefei (2014-2015): genetic characteristics of antimicrobial resistance.

    Science.gov (United States)

    Jiang, Fa-Xing; Lan, Qian; Le, Wen-Jing; Su, Xiao-Hong

    2017-05-25

    Antimicrobial resistance (AMR) and genetic determinants of resistance of N. gonorrhoeae isolates from Hefei, China, were characterized adding a breadth of information to the molecular epidemiology of gonococcal resistance in China. 126 N. gonorrhoeae isolates from a hospital clinic in Hefei, were collected between January, 2014, and November, 2015. The minimum inhibitory concentration (MIC) of N. gonorrhoeae isolates for seven antimicrobials were determined by the agar dilution method. Isolates were tested for mutations in penA and mtrR genes and 23S rRNA, and also genotyped using N. gonorrhoeae multi-antigen sequence typing (NG-MAST). All N. gonorrhoeae isolates were resistant to ciprofloxacin; 81.7% (103/126) to tetracycline and 73.8% (93/126) to penicillin. 39.7% (50/126) of isolates were penicillinase producing N. gonorrhoeae (PPNG), 31.7% (40/126) were tetracycline resistant N. gonorrhoeae (TRNG) and 28.6% (36/126) were resistant to azithromycin. While not fully resistant to extended spectrum cephalosporins (ESCs), a total of 14 isolates (11.1%) displayed decreased susceptibility to ceftriaxone (MIC ≥ 0.125 mg/L, n = 10), cefixime (MIC ≥ 0. 25 mg/L, n = 1) or to both ESCs (n = 3). penA mosaic alleles XXXV were found in all isolates that harbored decreased susceptibility to cefixime, except for one. Four mutations were found in mtrR genes and mutations A2143G and C2599T were identified in 23S rRNA. No isolates were resistant to spectinomycin. Gonococcal isolates were distributed into diverse NG-MAST sequence types (STs); 86 separate STs were identified. N. gonorrhoeae isolates from Hefei during 2014-2015, displayed high levels of resistance to antimicrobials that had been recommended previously for treatment of gonorrhea, e.g., penicillin, tetracycline and ciprofloxacin. The prevalence of resistance to azithromycin was also high (28.6%). No isolates were found to be fully resistant to spectinomycin, ceftriaxone or cefixime; however, 11

  4. Electrical Resistivity of an Elasmobranch's Ampullary Jelly in Varying Electric and Magnetic Fields

    Science.gov (United States)

    Brown, Brandon; Hughes, Mary E.

    2001-03-01

    The ampullae of Lorenzini are believed to function as the electroreceptive organs in elasmobranch fishes. Though the entire excised organs have been the subject of electrical transport measurements, the jelly that fills the ampullae -- composed primarily of glycoproteins with proteins and dissolved salts -- has received less scrutiny. The specific electromagnetic properties of the jelly contribute to electroreception, and we hope to supply useful parameters to modeling efforts via precise electrical characterization. We report preliminary resistivity measurements from ampullary jelly removed, post mortem, from an adult triaenodon obesus (white-tip reef shark). We present data over a broad range of applied electrical currents. We also present data of the resistivity as a function of applied magnetic field strength.

  5. Effects of Insecticides on Strawberry Aphid Chaetosiphon fragaefolii (Cockerell on Resistant and Susceptible Strawberry Genotypes

    Directory of Open Access Journals (Sweden)

    Slobodan Milenković

    2011-01-01

    Full Text Available Strawberry aphid, Chaetosiphon fragaefolii (Cockerell, is the most important vector ofstrawberry virus. Breeding of genotypes resistant to this pest is an important preventivecontrol measure, which can be compatible with rational insecticide application. The aimof the paper was to determine effects of dimethoate and deltamethrin on C. fragaefoliipopulations reared on two strawberry genotypes different in susceptibility: susceptiblestrawberry cultivar Čačanska rana and medium resistant hybrid, zf/1/94/96 (Senga Fructarinax Del Norte. Lower toxicity of deltamethrin was observed (laboratory assay as well aslower biological efficacy of dimethoate at lower concentrations (field trial for specimensfrom C. fragaefolii population reared on susceptible strawberry cultivar Čačanska rana.

  6. Trypanosoma cruzi: infection patterns in intact and athymic mice of susceptible and resistant genotypes.

    Science.gov (United States)

    Gonçalves da Costa, S C; Calabrese, K S; Zaverucha do Valle, T; Lagrange, P H

    2002-01-01

    Inbred strains of mice inoculated with the T cruzi Y strain behaved as susceptible (A/J, C3H/HeN), intermediate (BALB/c) or relatively resistant (C57BL/6) with respect to the magnitude of parasitaemia and mortality rate. C57BL/10 mice were susceptible in relation to parasitaemia but resistant when mortality was analyzed. Infection with T cruzi CL strain presented the same results, except for C57BL/6 which behaved as susceptible mice. Athymic mice of various backgrounds revealed no differences in susceptibility, presenting the same dramatic parasitaemia, tissue colonization pattern and no inflammatory reaction in any of the tissues studied. Infection of euthymic and athymic BALB/c mice elicited the production of parasite-specific antibodies, which reached similar levels on the first 9 days but differed after day 13. Serum transfer experiments in BALB/c mice did not show great differences in parasitaemia but altered T. cruzi polymorphism reducing the slender forms in athymic mice. Histopathology of athymic BALB/c mice showed the same tissue tropism when infected either with T cruzi Y or CL strain.

  7. Improvement of electrical resistivity tomography for leachate injection monitoring

    OpenAIRE

    Clément, R.; Descloitres, Marc; Gunther, T.; Oxarango, L.; Morra, C.; LAURENT, J.P.; Gourc, J.P.

    2010-01-01

    Leachate recirculation is a key process in the scope of operating municipal waste landfills as bioreactors, which aims to increase the moisture content to optimize the biodegradation in landfills. Given that liquid flows exhibit a complex behaviour in very heterogeneous porous media, in situ monitoring methods are required. Surface time-lapse electrical resistivity tomography (ERT) is usually proposed. Using numerical modelling with typical 2D and 3D injection plume patterns and 2D and 3D inv...

  8. Prevalence and antibiotic susceptibility of methicillin-resistant Staphylococcus aureus in ocular infections

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    Maria Eugenia Vola

    2013-12-01

    Full Text Available PURPOSE: To study the prevalence of methicillin-resistant Staphylococcus aureus among S. aureus ocular infections in a tertiary health center in Brazil and compare antibiotic susceptibility patterns between MRSA and methicillin-susceptible S. aureus isolates. METHODS: Electronic records from the ocular microbiology laboratory of the Universidade Federal de São Paulo were retrospectively reviewed. During a 10-year period (between January 2000 and December 2009 all conjunctivitis, keratitis, and endophthalmitis cases with a positive culture for S. aureus were identified. Antibiotic susceptibility was determined using the Kirby-Bauer disk diffusion method. RESULTS: Five hundred sixty-six S. aureus isolates were identified; of those, 56 (9.9% were resistant to methicillin. Throughout the 10-year period, Staphylococcus aureus showed a significant increasing trend from 7.55% to 16.18% among overall S. aurues infections (p=0.001 and from 3.7% to 13.16% in conjunctivitis (p=0.001. Conversely, we did not observe the same trend among those with keratitis (p=0.38. Staphylococcus aureus isolates showed higher resistance rates to tobramycin, gentamicin, ciprofloxacin, gatifloxacin, and moxifloxacin when compared with S. aureus isolates (p< 0.001. All cases were susceptible to vancomycin. CONCLUSION: We observed an increasing trend in the overall prevalence of Staphylococcus aureus ocular infections and statistically significant higher resistance rates to commonly used antibiotics compared to Staphylococcus aureus. Our data supports the need for constant bacterial surveillance and should be taken into consideration before initiating empiric treatment of ocular infections.

  9. In-vitro susceptibility of methicillin-resistant Staphylococcus aureus strains to antibiotics

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    İsmail Güler

    2011-12-01

    Full Text Available Objectives: Methicillin resistance of S.aureus strains sourced from hospitals and community-acquired has been increasing. The aim of this cross-sectional study is to determine the resistance rates to alternative antibiotics of meticilline resistant S.aureus (MRSA strains, where the multiple resistances are encountered the most.Materials and methods: A total of 100 MRSA strains isolated consequently from the clinical samples of hospitalized patients in Erciyes University Medical Faculty Hospitals between September 2008 and October 2009 were included in the study. According to “Clinical and Laboratory Standards Institude (CLSI” criteria, antimicrobial susceptibility testing was performed by Kirby-Bauer disk diffusion method.Results: The rates of resistance to antibiotics of the MRSA strains included within the study were 77% to erythromycin, 1% to trimethoprim/sulfamethoxazole (TMP-SXT, 90% to rifampin, 63% clindamycin, 84% to gentamicin and 0% to teicoplanin and vancomycin.Conclusion: All MRSA strains were susceptible to vancomycine and teicoplanin. On the other hand, TMP-SXT seems to be alternative agent for treatment of MRSA infections.

  10. Evaluation of Etest for Susceptibility Testing of Multidrug-Resistant Isolates of Mycobacterium tuberculosis†

    Science.gov (United States)

    Hazbón, Manzour Hernando; del Socorro Orozco, Maria; Labrada, Luz Angela; Tovar, Rafael; Weigle, Kristen A.; Wanger, Audrey

    2000-01-01

    To prescribe effective treatment schemes for patients with tuberculosis, more-efficient susceptibility testing techniques for Mycobacterium tuberculosis are needed, especially in regions with multidrug resistance. Etest (AB BIODISK, Solna, Sweden) is a simple technique that provides quantitative drug susceptibility results for M. tuberculosis in 5 to 10 days from a culture grown at low cost. The performance of Etest was compared to that of the reference proportion method, using 95 M. tuberculosis clinical isolates of which 42.1% (40 of 95) were resistant to at least one antibiotic by the reference method. Overall agreement between Etest and the reference method was 98.9% (94 of 95) for detection of multidrug resistance; for resistance to individual drugs, agreement was 97.9% (93 of 95) for rifampin, 96.0% (92 of 95) for ethambutol, 94.7% (90 of 95) for isoniazid, and 85.3% (81 of 95) for streptomycin. This study supports the utility of Etest for timely detection of drug resistance in M. tuberculosis and for use in tuberculosis control programs. PMID:11101602

  11. Serratia marcescens resistance profile and its susceptibility to photodynamic antimicrobial chemotherapy.

    Science.gov (United States)

    Parente, Ticiana Mont Alverne Lopes; Rebouças, Emanuela de Lima; Santos, Vitor Coutinho Vieira Dos; Barbosa, Francisco Cesar Barroso; Zanin, Iriana Carla Junqueira

    2016-06-01

    Some authors have reported the antimicrobial action of photodynamic antimicrobial chemotherapy (PACT) on bacteria related to nosocomial infections but there are few studies evaluating PACT on Serratia marcescens grown as planktonic cultures or as biofilms. The purpose of this study was to analyze the S. marcescens resistance profile and its susceptibility to PACT. Initially, 55 S. marcescens strains isolated from environmental, oral and extra-oral infections were tested by antimicrobial resistance to cefotaxime (CTX), imipenem (IPM), ciprofloxacin (CIP), tobramycin (TOB) and doxycycline (DOX) using E-test(®). Following, isolates grown as planktonic cultures or biofilms were submitted to PACT using the association of a light-emitting diode and toluidine blue (TBO). The E-test(®) results demonstrated intermediated sensitive strains to CTX, IMP, TOB, and DOX; and resistant strains to CTX, TOB, DOX and CIP. Also, CTX and IMP demonstrated variation when CLSI 2007 and CLSI 2015 were compared. Planktonic cultures and biofilms submitted to PACT demonstrated counts varying from 10(11) to 10(7) for planktonic cultures and 10(10) to 10(7) for biofilms. There were no statistical differences in the results when planktonic cultures and biofilms were compared. Increase in the profile of S. marcescens resistance was observed when CLSI 2007 and CLSI 2015 were compared. Also, IMP remains as the drug with lower rate of resistance. Additionally, both S. marcescens planktonic cultures and early biofilms are susceptible to PACT under tested conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Ambiguous Role of Interleukin-12 in Yersinia enterocolitica Infection in Susceptible and Resistant Mouse Strains

    Science.gov (United States)

    Bohn, Erwin; Schmitt, Edgar; Bielfeldt, Claudia; Noll, Annette; Schulte, Ralf; Autenrieth, Ingo B.

    1998-01-01

    Endogenous interleukin-12 (IL-12) mediates protection against Yersinia enterocolitica in C57BL/6 mice by triggering gamma interferon (IFN-γ) production in NK and CD4+ T cells. Administration of exogenous IL-12 confers protection against yersiniae in Yersinia-susceptible BALB/c mice but exacerbates yersiniosis in resistant C57BL/6 mice. Therefore, we wanted to dissect the different mechanisms exerted by IL-12 during Yersinia infections by using different models of Yersinia-resistant and -susceptible mice, including resistant C57BL/6 mice, susceptible BALB/c mice, intermediate-susceptible wild-type 129/Sv mice, 129/Sv IFN-γ-receptor-deficient (IFN-γR−/−) mice and C57BL/6 tumor necrosis factor (TNF) receptor p55 chain-deficient (TNFR p55−/−) mice. IFN-γR−/− mice turned out to be highly susceptible to infection by Y. enterocolitica compared with IFN-γR+/+ mice. Administration of IL-12 was protective in IFN-γR+/+ mice but not in IFN-γR−/− mice, suggesting that IFN-γR-induced mechanisms are essential for IL-12-induced resistance against yersiniae. BALB/c mice could be rendered Yersinia resistant by administration of anti-CD4 antibodies or by administration of IL-12. In contrast, C57BL/6 mice could be rendered more resistant by administration of transforming growth factor β (TGF-β). Furthermore, IL-12-triggered toxic effects in C57BL/6 mice were abrogated by coadministration of TGF-β. While administration of IL-12 alone increased TNF-α levels, administration of TGF-β or TGF-β plus IL-12 decreased both TNF-α and IFN-γ levels in Yersinia-infected C57BL/6 mice. Moreover, IL-12 did not induce toxicity in Yersinia-infected TNFR p55−/− mice, suggesting that TNF-α accounts for IL-12-induced toxicity. Taken together, IL-12 may induce different effector mechanisms in BALB/c and C57BL/6 mice resulting either in protection or exacerbation. These results are important for understanding the critical balance of proinflammatory and regulatory

  13. Metallic nanowire networks: effects of thermal annealing on electrical resistance

    Science.gov (United States)

    Langley, D. P.; Lagrange, M.; Giusti, G.; Jiménez, C.; Bréchet, Y.; Nguyen, N. D.; Bellet, D.

    2014-10-01

    Metallic nanowire networks have huge potential in devices requiring transparent electrodes. This article describes how the electrical resistance of metal nanowire networks evolve under thermal annealing. Understanding the behavior of such films is crucial for the optimization of transparent electrodes which find many applications. An in-depth investigation of silver nanowire networks under different annealing conditions provides a case study demonstrating that several mechanisms, namely local sintering and desorption of organic residues, are responsible for the reduction of the systems electrical resistance. Optimization of the annealing led to specimens with transmittance of 90% (at 550 nm) and sheet resistance of 9.5 Ω sq-1. Quantized steps in resistance were observed and a model is proposed which provides good agreement with the experimental results. In terms of thermal behavior, we demonstrate that there is a maximum thermal budget that these electrodes can tolerate due to spheroidization of the nanowires. This budget is determined by two main factors: the thermal loading and the wire diameter. This result enables the fabrication and optimization of transparent metal nanowire electrodes for solar cells, organic electronics and flexible displays.

  14. Laboratory Electrical Resistivity Studies on Cement Stabilized Soil

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    Nimi Ann Vincent

    2017-01-01

    Full Text Available Electrical resistivity measurement of freshly prepared uncured and cured soil-cement materials is done and the correlations between the factors controlling the performance of soil-cement and electrical resistivity are discussed in this paper. Conventional quality control of soil-cement quite often involves wastage of a lot of material, if it does not meet the strength criteria. In this study, it is observed that, in soil-cement, resistivity follows a similar trend as unconfined compressive strength, with increase in cement content and time of curing. Quantitative relations developed for predicting 7-day strength of soil-cement mix, using resistivity of the soil-cement samples at freshly prepared state, after 1-hour curing help to decide whether the soil-cement mix meets the desired strength and performance criteria. This offers the option of the soil-cement mix to be upgraded (possibly with additional cement in its fresh state itself, if it does not fulfil the performance criteria, rather than wasting the material after hardening.

  15. Laboratory Electrical Resistivity Studies on Cement Stabilized Soil.

    Science.gov (United States)

    Vincent, Nimi Ann; Shivashankar, R; Lokesh, K N; Jacob, Jinu Mary

    2017-01-01

    Electrical resistivity measurement of freshly prepared uncured and cured soil-cement materials is done and the correlations between the factors controlling the performance of soil-cement and electrical resistivity are discussed in this paper. Conventional quality control of soil-cement quite often involves wastage of a lot of material, if it does not meet the strength criteria. In this study, it is observed that, in soil-cement, resistivity follows a similar trend as unconfined compressive strength, with increase in cement content and time of curing. Quantitative relations developed for predicting 7-day strength of soil-cement mix, using resistivity of the soil-cement samples at freshly prepared state, after 1-hour curing help to decide whether the soil-cement mix meets the desired strength and performance criteria. This offers the option of the soil-cement mix to be upgraded (possibly with additional cement) in its fresh state itself, if it does not fulfil the performance criteria, rather than wasting the material after hardening.

  16. Transmission of Multidrug-Resistant and Drug-Susceptible Tuberculosis within Households: A Prospective Cohort Study.

    Directory of Open Access Journals (Sweden)

    Louis Grandjean

    2015-06-01

    Full Text Available The "fitness" of an infectious pathogen is defined as the ability of the pathogen to survive, reproduce, be transmitted, and cause disease. The fitness of multidrug-resistant tuberculosis (MDRTB relative to drug-susceptible tuberculosis is cited as one of the most important determinants of MDRTB spread and epidemic size. To estimate the relative fitness of drug-resistant tuberculosis cases, we compared the incidence of tuberculosis disease among the household contacts of MDRTB index patients to that among the contacts of drug-susceptible index patients.This 3-y (2010-2013 prospective cohort household follow-up study in South Lima and Callao, Peru, measured the incidence of tuberculosis disease among 1,055 household contacts of 213 MDRTB index cases and 2,362 household contacts of 487 drug-susceptible index cases. A total of 35/1,055 (3.3% household contacts of 213 MDRTB index cases developed tuberculosis disease, while 114/2,362 (4.8% household contacts of 487 drug-susceptible index patients developed tuberculosis disease. The total follow-up time for drug-susceptible tuberculosis contacts was 2,620 person-years, while the total follow-up time for MDRTB contacts was 1,425 person-years. Using multivariate Cox regression to adjust for confounding variables including contact HIV status, contact age, socio-economic status, and index case sputum smear grade, the hazard ratio for tuberculosis disease among MDRTB household contacts was found to be half that for drug-susceptible contacts (hazard ratio 0.56, 95% CI 0.34-0.90, p = 0.017. The inference of transmission in this study was limited by the lack of genotyping data for household contacts. Capturing incident disease only among household contacts may also limit the extrapolation of these findings to the community setting.The low relative fitness of MDRTB estimated by this study improves the chances of controlling drug-resistant tuberculosis. However, fitter multidrug-resistant strains that emerge

  17. Gene expression profiling in the thiamethoxam resistant and susceptible B-biotype sweetpotato whitefly, Bemisia tabaci.

    Science.gov (United States)

    Xie, Wen; Yang, Xin; Wang, Shao-Ii; Wu, Qing-jun; Yang, Ni-na; Li, Ru-mei; Jiao, Xiao-guo; Pan, Hui-peng; Liu, Bai-ming; Feng, Yun-tao; Xu, Bao-yun; Zhou, Xu-guo; Zhang, You-jun

    2012-01-01

    Thiamethoxam has been used as a major insecticide to control the B-biotype sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Due to its excessive use, a high level of resistance to thiamethoxam has developed worldwide over the past several years. To better understand the molecular mechanisms underlying this resistance in B. tabaci, gene profiles between the thiamethoxam-resistant and thiamethoxam-susceptible strains were investigated using the suppression subtractive hybridization (SSH) library approach. A total of 72 and 52 upand down-regulated genes were obtained from the forward and reverse SSH libraries, respectively. These expressed sequence tags (ESTs) belong to several functional categories based on their gene ontology annotation. Some categories such as cell communication, response to abiotic stimulus, lipid particle, and nuclear envelope were identified only in the forward library of thiamethoxam-resistant strains. In contrast, categories such as behavior, cell proliferation, nutrient reservoir activity, sequence-specific DNA binding transcription factor activity, and signal transducer activity were identified solely in the reverse library. To study the validity of the SSH method, 16 differentially expressed genes from both forward and reverse SSH libraries were selected randomly for further analyses using quantitative realtime PCR (qRT-PCR). The qRT-PCR results were fairly consistent with the SSH results; however, only 50% of the genes showed significantly different expression profiles between the thiamethoxam-resistant and thiamethoxam-susceptible whiteflies. Among these genes, a putative NAD-dependent methanol dehydrogenase was substantially over-expressed in the thiamethoxamresistant adults compared to their susceptible counterparts. The distributed profiles show that it was highly expressed during the egg stage, and was most abundant in the abdomen of adult females.

  18. Dynamic metabolic responses of brown planthoppers towards susceptible and resistant rice plants.

    Science.gov (United States)

    Liu, Caixiang; Du, Ba; Hao, Fuhua; Lei, Hehua; Wan, Qianfen; He, Guangcun; Wang, Yulan; Tang, Huiru

    2017-10-01

    Brown planthopper (Nilaparvata lugens Stål, BPH) causes huge economic losses in rice-growing regions, and new strategies for combating BPH are required. To understand how BPHs respond towards BPH-resistant plants, we systematically analysed the metabolic differences between BPHs feeding on the resistant and susceptible plants using NMR and GC-FID/MS. We also measured the expression of some related genes involving glycolysis and biosyntheses of trehalose, amino acids, chitin and fatty acids using real-time PCR. BPH metabonome was dominated by more than 60 metabolites including fatty acids, amino acids, carbohydrates, nucleosides/nucleotides and TCA cycle intermediates. After initial 12 h, BPHs feeding on the resistant plants had lower levels of amino acids, glucose, fatty acids and TCA cycle intermediates than on the susceptible ones. The levels of these metabolites recovered after 24 h feeding. This accompanied with increased level in trehalose, choline metabolites and nucleosides/nucleotides compared with BPH feeding on the susceptible plants. Decreased levels of BPH metabolites at the early feeding probably resulted from less BPH uptakes of sap from resistant plants and recovery of BPH metabolites at the later stage probably resulted from their adaptation to the adverse environment with their increased hopping frequency to ingest more sap together with contributions from yeast-like symbionts in BPHs. Throughout 96 h, BPH feeding on the resistant plants showed significant up-regulation of chitin synthase catalysing biosynthesis of chitin for insect exoskeleton, peritrophic membrane lining gut and tracheae. These findings provided useful metabolic information for understanding the BPH-rice interactions and perhaps for developing new BPH-combating strategies. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

  19. In vivo activity of Sapindus saponaria against azole-susceptible and -resistant human vaginal Candida species.

    Science.gov (United States)

    Damke, Edílson; Tsuzuki, Joyce K; Cortez, Diógenes A G; Ferreira, Izabel C P; Bertoni, Thâmara A; Batista, Márcia R; Donati, Lucélia; Svidzinski, Terezinha I E; Consolaro, Márcia E L

    2011-05-04

    Study of in vivo antifungal activity of the hydroalcoholic extract (HE) and n-BuOH extract (BUTE) of Sapindus saponaria against azole-susceptible and -resistant human vaginal Candida spp. The in vitro antifungal activity of HE, BUTE, fluconazole (FLU), and itraconazole (ITRA) was determined by the broth microdilution method. We obtained values of minimal inhibitory concentration (MIC) and minimum fungicide concentration (MFC) for 46 strains of C. albicans and 10 of C. glabrata isolated from patients with vulvovaginal candidiasis (VVC). VVC was induced in hyperestrogenic Wistar rats with azole-susceptible C. albicans (SCA), azole-resistant C. albicans (RCA), and azole-resistant C. glabrata (RCG). The rats were treated intravaginally with 0.1 mL of HE or BUTE at concentrations of 1%, 2.5% and 5%; 100 μg/mL of FLU (treatment positive control); or distilled water (negative control) at 1, 24, and 48 h after induction of the infection, and the progress of VVC was monitored by culturing and scanning electron microscopy (SEM). The toxicity was evaluated in cervical cells of the HeLa cell line. The extracts showed in vitro inhibitory and fungicidal activity against all the isolates, and the MIC and MFC values for the C. glabrata isolates were slightly higher. In vivo, the SCA, RCA, and RCG infections were eliminated by 21 days post-infection, with up to 5% HE and BUTE, comparable to the activity of FLU. No cytotoxic action was observed for either extract. Our results demonstrated that HE and BUTE from S. saponaria show inhibitory and fungicidal activity in vitro, in addition to in vivo activity against azole-resistant vaginal isolates of C. glabrata and azole-susceptible and resistant isolates of C. albicans. Also considering the lack of cytotoxicity and the low concentrations of the extracts necessary to eliminate the infection in vivo, HE and BUTE show promise for continued studies with purified antifungal substances in VVC yeast isolates.

  20. Genetic profiles of ten Dirofilaria immitis isolates susceptible or resistant to macrocyclic lactone heartworm preventives.

    Science.gov (United States)

    Bourguinat, Catherine; Keller, Kathy; Xia, Jianguo; Lepage, Pierre; McTier, Tom L; Woods, Debra J; Prichard, Roger K

    2017-11-09

    For dogs and cats, chemoprophylaxis with macrocyclic lactone (ML) preventives for heartworm disease is widely used in the United States and other countries. Since 2005, cases of loss of efficacy (LOE) of heartworm preventives have been reported in the U.S. More recently, ML-resistant D. immitis isolates were confirmed. Previous work identified 42 genetic markers that could predict ML response in individual samples. For field surveillance, it would be more appropriate to work on microfilarial pools from individual dogs with a smaller subset of genetic markers. MiSeq technology was used to identify allele frequencies with the 42 genetic markers previously reported. Microfilaria from ten well-characterized new isolates called ZoeKY, ZoeMI, ZoeGCFL, ZoeAL, ZoeMP3, ZoeMO, ZoeAMAL, ZoeLA, ZoeJYD-34, and Metairie were extracted from fresh blood from dogs. DNA were extracted and sequenced with MiSeq technology. Allele frequencies were calculated and compared with the previously reported susceptible, LOE, and resistant D. immitis populations. The allele frequencies identified in the current resistant and susceptible isolates were in accordance with the allele frequencies previously reported in related phenotypes. The ZoeMO population, a subset of the ZoeJYD-34 population, showed a genetic profile that was consistent with some reversion towards susceptibility compared with the parental ZoeJYD-34 population. The Random Forest algorithm was used to create a predictive model using different SNPs. The model with a combination of three SNPs (NODE_42411_RC, NODE_21554_RC, and NODE_45689) appears to be suitable for future monitoring. MiSeq technology provided a suitable methodology to work with the microfilarial samples. The list of SNPs that showed good predictability for ML resistance was narrowed. Additional phenotypically well characterized D. immitis isolates are required to finalize the best set of SNPs to be used for large scale ML resistance screening.

  1. Relation between genetic markers of drug resistance and susceptibility profile of clinical Neisseria gonorrhoeae strains.

    Science.gov (United States)

    Ilina, Elena N; Vereshchagin, Vladimir A; Borovskaya, Alexandra D; Malakhova, Maja V; Sidorenko, Sergei V; Al-Khafaji, Nazar C; Kubanova, Anna A; Govorun, Vadim M

    2008-06-01

    The main goal of this work is to clarify the predictive value of known genetic markers of Neisseria gonorrhoeae resistance to penicillin, tetracycline, and fluoroquinolones. The correlation between the presence of certain genetic markers and susceptibility of N. gonorrhoeae isolates to penicillin, tetracycline, and fluoroquinolones has been analyzed by means of statistical methods. Susceptibility testing with penicillin, tetracycline, and fluoroquinolones was performed by the agar dilution method. N. gonorrhoeae genomic DNA was isolated. The presence of bla(TEM-1) and tet(M) genes was analyzed by PCR. A novel method of polymorphism discovery based on a minisequencing reaction followed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry was applied for the analysis of chromosomal N. gonorrhoeae genes involved in antimicrobial resistance development. Clinical N. gonorrhoeae isolates (n = 464) were collected. Susceptibility levels to penicillin, tetracycline, and fluoroquinolones were found to be 25.9%, 35.9%, and 54.1%, respectively. Among the 19 N. gonorrhoeae isolates with penicillin MICs of > or =4 microg/ml, the bla(TEM-1) gene was detected in 12. The Tet(M) determinant was found in 4 of 12 N. gonorrhoeae isolates with tetracycline MICs of > or =16 microg/ml. The chromosomal genetic markers of penicillin and tetracycline resistance were detected especially in isolates with penicillin MICs of 0.25 to 2.0 microg/ml and tetracycline MICs of 0.5 to 4 microg/ml. Mutations in GyrA and ParC were found in 208 of 211 quinolone-resistant N. gonorrhoeae isolates. This work is the first representative molecular research of the N. gonorrhoeae population in Russia. Information about the prevalence of antibiotic resistance mechanisms and the positive predictive value of certain genetic determinants is given. The positive predictive values of the analyzed genetic markers were found to be different for fluoroquinolones (90.3%), penicillin (91.1%), and

  2. Binding and Oligomerization of Modified and Native Bt Toxins in Resistant and Susceptible Pink Bollworm.

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    Josue Ocelotl

    Full Text Available Insecticidal proteins from Bacillus thuringiensis (Bt are used extensively in sprays and transgenic crops for pest control, but their efficacy is reduced when pests evolve resistance. Better understanding of the mode of action of Bt toxins and the mechanisms of insect resistance is needed to enhance the durability of these important alternatives to conventional insecticides. Mode of action models agree that binding of Bt toxins to midgut proteins such as cadherin is essential for toxicity, but some details remain unresolved, such as the role of toxin oligomers. In this study, we evaluated how Bt toxin Cry1Ac and its genetically engineered counterpart Cry1AcMod interact with brush border membrane vesicles (BBMV from resistant and susceptible larvae of Pectinophora gossypiella (pink bollworm, a global pest of cotton. Compared with Cry1Ac, Cry1AcMod lacks 56 amino acids at the amino-terminus including helix α-1; previous work showed that Cry1AcMod formed oligomers in vitro without cadherin and killed P. gossypiella larvae harboring cadherin mutations linked with >1000-fold resistance to Cry1Ac. Here we found that resistance to Cry1Ac was associated with reduced oligomer formation and insertion. In contrast, Cry1AcMod formed oligomers in BBMV from resistant larvae. These results confirm the role of cadherin in oligomerization of Cry1Ac in susceptible larvae and imply that forming oligomers without cadherin promotes toxicity of Cry1AcMod against resistant P. gossypiella larvae that have cadherin mutations.

  3. Regulation of resistance and susceptibility in wheat-powdery mildew pathosystem with exogenous cytokinins.

    Science.gov (United States)

    Babosha, Alexander V

    2009-11-15

    Dose-response relationship between resistance of wheat seedlings (Triticum aestivum, cultivar Zarya) to Erysiphe graminis f. sp. tritici Marchal. (Syn. Blumeria graminis), a causal organism of wheat powdery mildew and exogenous zeatin has been investigated. Two-week-old seedlings were inoculated with the pathogen. Zeatin or zeatinriboside were added to the nutrient solution immediately after inoculation. The dose-response curve of cytokinin in the most cases was multiphasic, with peaks of increased susceptibility occurring at 0.25-1.5 and 1.5-9microM cytokinin, separated by a region of increased resistance at 0.5-3microM cytokinin. The change in mineral nutrition or simultaneous treatment with thidiazuron revealed alterations of the dose-response curve ranging from a curve with maximum of resistance to a curve with maximum of susceptibility. Both multiphase nature of dose-response and its variability were proposed as possible explanations for earlier observed discrepancies in experimental data on modification of disease resistance by cytokinins. A mathematical model for two metabolic processes with substrate inhibition connected in-series was suggested to explain the multiphase dose-response. In this model, the product of the first reaction was used as substrate for the second reaction. Numerical experiments showed the changes in the shape of dose-response curve with changes in parameters dependent of cytokinin metabolism.

  4. Bacteriological profile and antibiotic susceptibility patterns in neonatal septicemia in view of emerging drug resistance

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    Maimoona Mustafa

    2014-02-01

    Full Text Available The objective of this study was to isolate pathogenic bacteria in neo-natal septicaemia cases, and to know their antibiograms. Under aseptic precautions, blood was drawn from 140 neonates with sus-pected septicaemia and inoculated in brain heart infusion (BHI broth. Isolates obtained were identified as per standard protocol and antibi-otic susceptibility was done by Kirby Bauer disc diffusion method (as per CLSI guidelines. A total number of 62 (44.2% patients had positive blood cultures. The most common pathogens isolated were Klebsiella pneumoniae (n=22, 35% followed by Staphylococcus aureus (n=15, 24.1%, Escherichia coli (n=14, 22.5%, CONS (n=7, 11.2% and Pseudomonas aeruginosa (n=4, 6.4%. The Gram nega-tive organisms showed high resistance to commonly used antibiotics and were highly sensitive to Meropenem. The Gram positive bacteria showed high resistance to Ampicillin, Erythromycin and Amoxycillin; but they were highly susceptible to Linizolid and Vancomycin. As the Gram negative organisms were the most common isolates in neona-tal septicemia, their resistance pattern should be considered essen-tial for deciding the empirical treatment. Prompt treatment of neonatal sepsis with judicious use of appropriate antibiotics can minimize the morbidity and mortality, besides reducing the emergence of multi-drug resistant organisms in intensive care units (ICUs.

  5. Downy mildew resistance induced by Trichoderma harzianum T39 in susceptible grapevines partially mimics transcriptional changes of resistant genotypes

    Science.gov (United States)

    2012-01-01

    Background Downy mildew, caused by Plasmopara viticola, is one of the most severe diseases of grapevine and is commonly controlled by fungicide treatments. The beneficial microorganism Trichoderma harzianum T39 (T39) can induce resistance to downy mildew, although the molecular events associated with this process have not yet been elucidated in grapevine. A next generation RNA sequencing (RNA-Seq) approach was used to study global transcriptional changes associated with resistance induced by T39 in Vitis vinifera Pinot Noir leaves. The long-term aim was to develop strategies to optimize the use of this agent for downy mildew control. Results More than 14.8 million paired-end reads were obtained for each biological replicate of T39-treated and control leaf samples collected before and 24 h after P. viticola inoculation. RNA-Seq analysis resulted in the identification of 7,024 differentially expressed genes, highlighting the complex transcriptional reprogramming of grapevine leaves during resistance induction and in response to pathogen inoculation. Our data show that T39 has a dual effect: it directly modulates genes related to the microbial recognition machinery, and it enhances the expression of defence-related processes after pathogen inoculation. Whereas several genes were commonly affected by P. viticola in control and T39-treated plants, opposing modulation of genes related to responses to stress and protein metabolism was found. T39-induced resistance partially inhibited some disease-related processes and specifically activated defence responses after P. viticola inoculation, causing a significant reduction of downy mildew symptoms. Conclusions The global transcriptional analysis revealed that defence processes known to be implicated in the reaction of resistant genotypes to downy mildew were partially activated by T39-induced resistance in susceptible grapevines. Genes identified in this work are an important source of markers for selecting novel

  6. Downy mildew resistance induced by Trichoderma harzianum T39 in susceptible grapevines partially mimics transcriptional changes of resistant genotypes

    Directory of Open Access Journals (Sweden)

    Perazzolli Michele

    2012-11-01

    Full Text Available Abstract Background Downy mildew, caused by Plasmopara viticola, is one of the most severe diseases of grapevine and is commonly controlled by fungicide treatments. The beneficial microorganism Trichoderma harzianum T39 (T39 can induce resistance to downy mildew, although the molecular events associated with this process have not yet been elucidated in grapevine. A next generation RNA sequencing (RNA-Seq approach was used to study global transcriptional changes associated with resistance induced by T39 in Vitis vinifera Pinot Noir leaves. The long-term aim was to develop strategies to optimize the use of this agent for downy mildew control. Results More than 14.8 million paired-end reads were obtained for each biological replicate of T39-treated and control leaf samples collected before and 24 h after P. viticola inoculation. RNA-Seq analysis resulted in the identification of 7,024 differentially expressed genes, highlighting the complex transcriptional reprogramming of grapevine leaves during resistance induction and in response to pathogen inoculation. Our data show that T39 has a dual effect: it directly modulates genes related to the microbial recognition machinery, and it enhances the expression of defence-related processes after pathogen inoculation. Whereas several genes were commonly affected by P. viticola in control and T39-treated plants, opposing modulation of genes related to responses to stress and protein metabolism was found. T39-induced resistance partially inhibited some disease-related processes and specifically activated defence responses after P. viticola inoculation, causing a significant reduction of downy mildew symptoms. Conclusions The global transcriptional analysis revealed that defence processes known to be implicated in the reaction of resistant genotypes to downy mildew were partially activated by T39-induced resistance in susceptible grapevines. Genes identified in this work are an important source of markers

  7. Trends towards Lower Antimicrobial Susceptibility and Characterization of Acquired Resistance among Clinical Isolates of Brachyspira hyodysenteriae in Spain

    DEFF Research Database (Denmark)

    Hidalgo, Alvaro; Carvajal, Ana; Vester, Birte

    2011-01-01

    The antimicrobial susceptibility of clinical isolates of Brachyspira hyodysenteriae in Spain was monitored, and the underlying molecular mechanisms of resistance were investigated. MICs of tylosin, tiamulin, valnemulin, lincomycin, and tylvalosin were determined for 87 B. hyodysenteriae isolates ...

  8. An integrated epigenetic and genetic analysis of DNA methyltransferase genes (DNMTs) in tumor resistant and susceptible chicken lines

    National Research Council Canada - National Science Library

    Yu, Ying; Zhang, Huanmin; Tian, Fei; Zhang, Wensheng; Fang, Hongbin; Song, Jiuzhou

    2008-01-01

    ... (DNMT3a, DNMT3b and DNMT1). DNA mutations and DNA methylation profiles of DNMTs themselves and their relationships with chicken neoplastic disease resistance and susceptibility are not yet defined...

  9. Global and local variations in antimicrobial susceptibilities and resistance development in the major respiratory pathogens.

    Science.gov (United States)

    Alpuche, Celia; Garau, Javier; Lim, Victor

    2007-12-01

    Acute respiratory tract infections, such as bacterial pneumonia and acute exacerbations of chronic bronchitis, have been identified by the World Health Organisation as the leading global infectious cause of death. An increasing prevalence of antibiotic resistance has been identified worldwide in the three major bacterial respiratory pathogens -Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae. The selection and spread of resistance is to some degree inevitable and the importance of monitoring its progress has led to the instigation of numerous international, regional and national surveillance programmes. The results from surveillance studies show wide variations in susceptibility rates, both geographically and over time, highlighting the need for local resistance prevalence data in order to guide empirical prescribing and to identify areas in which medical need for new agents is greatest.

  10. Antibiotic susceptibility of members of the Lactobacillus acidophilus group using broth microdilution and molecular identification of their resistance determinants

    NARCIS (Netherlands)

    Mayrhofer, S.; Hoek, van A.H.A.M.; Mair, C.; Huys, G.; Aarts, H.J.M.; Kneifel, W.; Domig, K.J.

    2010-01-01

    The range of antibiotic susceptibility to 13 antibiotics in 101 strains of the Lactobacillus acidophilus group was examined using the lactic acid bacteria susceptibility test medium (LSM) and broth microdilution. Additionally, microarray analysis and PCR were applied to identify resistance genes

  11. Transcriptome analysis of resistant and susceptible alfalfa cultivars infected with root-knot nematode Meloidogyne incognita.

    Science.gov (United States)

    Postnikova, Olga A; Hult, Maria; Shao, Jonathan; Skantar, Andrea; Nemchinov, Lev G

    2015-01-01

    Nematodes are one of the major limiting factors in alfalfa production. Root-knot nematodes (RKN, Meloidogyne spp.) are widely distributed and economically important sedentary endoparasites of agricultural crops and they may inflict significant damage to alfalfa fields. As of today, no studies have been published on global gene expression profiling in alfalfa infected with RKN or any other plant parasitic nematode. Very little information is available about molecular mechanisms that contribute to pathogenesis and defense responses in alfalfa against these pests and specifically against RKN. In this work, we performed root transcriptome analysis of resistant (cv. Moapa 69) and susceptible (cv. Lahontan) alfalfa cultivars infected with RKN Meloidogyne incognita, widespread root-knot nematode species and a major pest worldwide. A total of 1,701,622,580 pair-end reads were generated on an Illumina Hi-Seq 2000 platform from the roots of both cultivars and assembled into 45,595 and 47,590 transcripts in cvs Moapa 69 and Lahontan, respectively. Bioinformatic analysis revealed a number of common and unique genes that were differentially expressed in susceptible and resistant lines as a result of nematode infection. Although the susceptible cultivar showed a more pronounced defense response to the infection, feeding sites were successfully established in its roots. Characteristically, basal gene expression levels under normal conditions differed between the two cultivars as well, which may confer advantage to one of the genotypes toward resistance to nematodes. Differentially expressed genes were subsequently assigned to known Gene Ontology categories to predict their functional roles and associated biological processes. Real-time PCR validated expression changes in genes arbitrarily selected for experimental confirmation. Candidate genes that contribute to protection against M. incognita in alfalfa were proposed and alfalfa-nematode interactions with respect to resistance

  12. Comparative Proteomic Analysis of Susceptible and Resistant Rice Plants during Early Infestation by Small Brown Planthopper.

    Science.gov (United States)

    Dong, Yan; Fang, Xianping; Yang, Yong; Xue, Gang-Ping; Chen, Xian; Zhang, Weilin; Wang, Xuming; Yu, Chulang; Zhou, Jie; Mei, Qiong; Fang, Wang; Yan, Chengqi; Chen, Jianping

    2017-01-01

    The small brown planthopper (Laodelphax striatellus Fallén, Homoptera, Delphacidae-SBPH) is one of the major destructive pests of rice (Oryza sativa L.). Understanding on how rice responds to SBPH infestation will contribute to developing strategies for SBPH control. However, the response of rice plant to SBPH is poorly understood. In this study, two contrasting rice genotypes, Pf9279-4 (SBPH-resistant) and 02428 (SBPH-susceptible), were used for comparative analysis of protein profiles in the leaf sheath of rice plants in responses to SBPH infestation. One hundred and thirty-two protein spots that were differentially expressed between the resistant and susceptible rice lines were identified with significant intensity differences (≥2-fold, P < 0.05) at 0, 6, and 12 h after SBPH infestation. Protein expression profile analysis in the leaf sheath of SBPH-resistant and SBPH-susceptible rice lines after SBPH infestation showed that proteins induced by SBPH feeding were involved mainly in stress response, photosynthesis, protein metabolic process, carbohydrate metabolic process, energy metabolism, cell wall-related proteins, amino acid metabolism and transcriptional regulation. Gene expression analysis of 24 differentially expressed proteins (DEPs) showed that more than 50% DEPs were positively correlated with their mRNA levels. Analysis of some physiological indexes mainly involved in the removal of oxygen reactive species showed that the levels of superoxide dismutase (SOD) and glutathione (GSH) were considerably higher in Pf9279-4 than 02428 during SBPH infestation. The catalase (CAT) activity and hydroxyl radical inhibition were lower in Pf9279-4 than 02428. Analysis of enzyme activities indicates that Pf9279-4 rice plants defend against SBPH through the activation of the pathway of the salicylic acid (SA)-dependent systemic acquired resistance. In conclusion, this study provides some insights into the molecular networks involved on cellular and physiological

  13. Comparative Proteomic Analysis of Susceptible and Resistant Rice Plants during Early Infestation by Small Brown Planthopper

    Directory of Open Access Journals (Sweden)

    Yan Dong

    2017-10-01

    Full Text Available The small brown planthopper (Laodelphax striatellus Fallén, Homoptera, Delphacidae-SBPH is one of the major destructive pests of rice (Oryza sativa L.. Understanding on how rice responds to SBPH infestation will contribute to developing strategies for SBPH control. However, the response of rice plant to SBPH is poorly understood. In this study, two contrasting rice genotypes, Pf9279-4 (SBPH-resistant and 02428 (SBPH-susceptible, were used for comparative analysis of protein profiles in the leaf sheath of rice plants in responses to SBPH infestation. One hundred and thirty-two protein spots that were differentially expressed between the resistant and susceptible rice lines were identified with significant intensity differences (≥2-fold, P < 0.05 at 0, 6, and 12 h after SBPH infestation. Protein expression profile analysis in the leaf sheath of SBPH-resistant and SBPH-susceptible rice lines after SBPH infestation showed that proteins induced by SBPH feeding were involved mainly in stress response, photosynthesis, protein metabolic process, carbohydrate metabolic process, energy metabolism, cell wall-related proteins, amino acid metabolism and transcriptional regulation. Gene expression analysis of 24 differentially expressed proteins (DEPs showed that more than 50% DEPs were positively correlated with their mRNA levels. Analysis of some physiological indexes mainly involved in the removal of oxygen reactive species showed that the levels of superoxide dismutase (SOD and glutathione (GSH were considerably higher in Pf9279-4 than 02428 during SBPH infestation. The catalase (CAT activity and hydroxyl radical inhibition were lower in Pf9279-4 than 02428. Analysis of enzyme activities indicates that Pf9279-4 rice plants defend against SBPH through the activation of the pathway of the salicylic acid (SA-dependent systemic acquired resistance. In conclusion, this study provides some insights into the molecular networks involved on cellular and

  14. Cigarette Smoke Induces Immune Responses to Vimentin in both, Arthritis-Susceptible and -Resistant Humanized Mice.

    Directory of Open Access Journals (Sweden)

    Mitali Bidkar

    Full Text Available Rheumatoid arthritis (RA is an autoimmune disease marked by chronic synovial inflammation and both, genetic and environmental factors are involved in its pathogenesis. Human leukocyte antigen (HLA DRB1*0401 is associated with susceptibility to develop RA, while cigarette smoke (CS exposure promotes seropositive disease with increased severity in DRB1*0401+ individuals. Smokers have higher levels of antibodies against citrullinated peptides. In this study, we determined whether the response to a known autoantigen, Vimentin (Vim is shared epitope specific and how CS influences this response using transgenic-mice carrying RA-susceptible,*0401, and -resistant, *0402, genes. Following relatively brief exposure to CS, peptidyl arginine deiminase (PAD enzyme expression was increased in murine lungs. Cigarette smoking led to production of Interferon (IFN-γ with reduced levels of Interleukin (IL-10 by splenocytes of *0401 mice. In contrast, CS augmented Th2 cytokines along with T-regulatory cells in *0402 mice. An increase in levels of antibodies to native and citrullinated Vim was observed in naïve mice of both strains following CS exposure. Our data showed that both arthritis-susceptible and -resistant mice can generate cellular and humoral immunity to Vim; however CS-induced modulation of host immunity is dependent on the interaction with the host HLA genes.

  15. Antimicrobial susceptibility of methicillin-resistant Staphylococcus pseudintermedius isolated from veterinary clinical cases in the UK.

    Science.gov (United States)

    Maluping, R P; Paul, N C; Moodley, A

    2014-01-01

    Staphylococcus pseudintermedius is a leading aetiologic agent of pyoderma and other body tissue infections in dogs and cats. In recent years, an increased prevalence of methicillin-resistant S. pseudintermedius (MRSP) has been reported. Isolation of MRSP in serious infections poses a major therapeutic challenge as strains are often resistant to all forms of systemic antibiotic used to treat S. pseudintermedius -related infections. This study investigates the occurrence of MRSP from a total of 7183 clinical samples submitted to the authors' laboratories over a 15-month period. Identification was based on standard microbiological identification methods, and by S. pseudintermedius-specific nuc polymerase chain reaction (PCR). Methicillin resistance was confirmed by PBP2a latex agglutination and mecA PCR. Susceptibility against non-beta-lactam antibiotics was carried out using a disc-diffusion method according to Clinical and Laboratory Standards Institute (CLSI) guidelines. In addition, susceptibility to pradofloxacin--a new veterinary fluoroquinolone--was also investigated. SCCmec types were determined by multiplex PCR. Staphylococcus pseudintermedius was isolated from 391 (5%) samples and 20 were confirmed as MRSP from cases of pyoderma, otitis, wound infections, urinary tract infection and mastitis in dogs only. All 20 isolates were resistant to clindamycin and sulphamethoxazole/trimethoprim. Nineteen were resistant to chloramphenicol, enrofloxacin, gentamicin, marbofloxacin and pradofloxacin; additionally, seven isolates were resistant to tetracycline. Fifteen isolates carried SCCmec type II-III, four isolates had type V and one harboured type IV. To date, only a few scientific papers on clinical MRSP strains isolated from the UK have been published, thus the results from this study would provide additional baseline data for further investigations.

  16. Comparative Life Histories of Greenbugs and Sugarcane Aphids (Hemiptera: Aphididae) Coinfesting Susceptible and Resistant Sorghums.

    Science.gov (United States)

    Bayoumy, Mohamed H; Perumal, Ramaswamy; Michaud, J P

    2016-02-01

    Host-plant resistance has been a fundamental component of aphid management in cereal crops. Over decades, various sources of resistance to greenbug, Schizaphis graminum (Rondani), were bred into cultivars of sorghum, Sorghum bicolor (L.) Moench, to counter recurring virulent greenbug biotypes. The recent invasion of sugarcane aphid, Melanaphis sacchari (Zehntner), raised questions about plant-mediated interactions between the two aphids and the possibility of using greenbug antibiosis against sugarcane aphid. The present work was undertaken to characterize the impact of PI 550610 resistance to 'biotype I' greenbug, expressed in seed parental line KS 116B, on aphid life histories and to observe plant-mediated interactions between aphid species in its presence and absence. At 23°C, sugarcane aphid nymphs matured 1.5 d faster than greenbug nymphs on susceptible hybrid P8500, but at similar rates on the resistant line, which delayed maturity by 1-1.5 d in both species and increased juvenile mortality by three- to fourfold. Sugarcane aphid reproductive rate was double that of greenbug on susceptible sorghum (4.45 vs. 2.30 nymphs per female per day), but not significantly different on the resistant one (3.09 vs. 2.27). Thus, PI 550610 expresses antibiosis, not tolerance, to these aphids. Coinfestation of P8500 had a positive effect on greenbug intrinsic rate of increase (rm), which changed to negative on KS 116B, whereas the rm of sugarcane aphid was unaffected by coinfestation with greenbug on either cultivar. The results indicate that KS 116B will be useful for producing sugarcane aphid-resistant hybrids, and that PI 550610 antibiosis changes the sugarcane aphid-greenbug interspecific relationship from commensalism to amensalism. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  17. Comparative Genomics of Two ST 195 Carbapenem-Resistant Acinetobacter baumannii with Different Susceptibility to Polymyxin Revealed Underlying Resistance Mechanism

    Science.gov (United States)

    Lean, Soo-Sum; Yeo, Chew Chieng; Suhaili, Zarizal; Thong, Kwai-Lin

    2016-01-01

    Acinetobacter baumannii is a Gram-negative nosocomial pathogen of importance due to its uncanny ability to acquire resistance to most antimicrobials. These include carbapenems, which are the drugs of choice for treating A. baumannii infections, and polymyxins, the drugs of last resort. Whole genome sequencing was performed on two clinical carbapenem-resistant A. baumannii AC29 and AC30 strains which had an indistinguishable ApaI pulsotype but different susceptibilities to polymyxin. Both genomes consisted of an approximately 3.8 Mbp circular chromosome each and several plasmids. AC29 (susceptible to polymyxin) and AC30 (resistant to polymyxin) belonged to the ST195 lineage and are phylogenetically clustered under the International Clone II (IC-II) group. An AbaR4-type resistance island (RI) interrupted the comM gene in the chromosomes of both strains and contained the blaOXA−23 carbapenemase gene and determinants for tetracycline and streptomycin resistance. AC29 harbored another copy of blaOXA−23 in a large (~74 kb) conjugative plasmid, pAC29b, but this gene was absent in a similar plasmid (pAC30c) found in AC30. A 7 kb Tn1548::armA RI which encodes determinants for aminoglycoside and macrolide resistance, is chromosomally-located in AC29 but found in a 16 kb plasmid in AC30, pAC30b. Analysis of known determinants for polymyxin resistance in AC30 showed mutations in the pmrA gene encoding the response regulator of the two-component pmrAB signal transduction system as well as in the lpxD, lpxC, and lpsB genes that encode enzymes involved in the biosynthesis of lipopolysaccharide (LPS). Experimental evidence indicated that impairment of LPS along with overexpression of pmrAB may have contributed to the development of polymyxin resistance in AC30. Cloning of a novel variant of the blaAmpC gene from AC29 and AC30, and its subsequent expression in E. coli also indicated its likely function as an extended-spectrum cephalosporinase. PMID:26779129

  18. Comparative genomics of two ST 195 carbapenem-resistant Acinetobacter baumannii with different susceptibility to polymyxin revealed underlying resistance mechanism

    Directory of Open Access Journals (Sweden)

    Soo Sum eLean

    2016-01-01

    Full Text Available Acinetobacter baumannii is a Gram-negative nosocomial pathogen of importance due to its uncanny ability to acquire resistance to most antimicrobials. These include carbapenems, which are the drugs of choice for treating A. baumannii infections, and polymyxins, the drugs of last resort. Whole genome sequencing was performed on two clinical carbapenem-resistant A. baumannii AC29 and AC30 strains which had an indistinguishable ApaI pulsotype but different susceptibilities to polymyxin. Both genomes consisted of an approximately 3.8 Mbp circular chromosome each and several plasmids. AC29 (susceptible to polymyxin and AC30 (resistant to polymyxin belonged to the ST195 lineage and are phylogenetically clustered under the International Clone III (IC-III group. An AbaR4-type resistance island (RI interrupted the comM gene in the chromosomes of both strains and contained the blaOXA-23 carbapenemase gene and determinants for tetracycline and streptomycin resistance. AC29 harboured another copy of blaOXA-23 in a large (~74 kb conjugative plasmid, pAC29b, but this gene was absent in a similar plasmid (pAC30c found in AC30. A 7 kb Tn1548::armA RI which encodes determinants for aminoglycoside and macrolide resistance, is chromosomally-located in AC29 but found in a 16 kb plasmid in AC30, pAC30b. Analysis of known determinants for polymyxin resistance in AC30 showed mutations in the pmrA gene encoding the response regulator of the two-component pmrAB signal transduction system as well as in the lpxD, lpxC and lpsB genes that encode enzymes involved in the biosynthesis of lipopolysaccharide (LPS. Experimental evidence indicated that impairment of LPS along with overexpression of pmrAB may have contributed to the development of polymyxin resistance in AC30. Cloning of a novel variant of the blaAmpC gene from AC29 and AC30, and its subsequent expression in E. coli also indicated its likely function as an extended-spectrum cephalosporinase

  19. Development of a test method for determining the cracking susceptibility of resistance spot welded high strength steel sheets

    OpenAIRE

    Rethmeier, Michael; Suwala, Hubert

    2014-01-01

    In this study a test method for determining the cracking susceptibility of resistance spot welded high strength steel sheets was investigated. The development of a suitable test procedure is based on the External-Loaded Hot Crack Test (PVC-Test). The test modification for resistance spot welding contains a constant tensile force load. The test method for determining the cracking susceptibility was experimentally verified for a high strength steel, a transformation induced plasticity steel (TR...

  20. Susceptibility of Pediococcus isolates to antimicrobial compounds in relation to hop-resistance and beer-spoilage

    Directory of Open Access Journals (Sweden)

    Ziola Barry

    2009-09-01

    Full Text Available Abstract Background Though important in the context of food microbiology and as potential pathogens in immuno-compromised humans, bacterial isolates belonging to the genus Pediococcus are best known for their association with contamination of ethanol fermentation processes (beer, wine, or fuel ethanol. Use of antimicrobial compounds (e.g., hop-compounds, Penicillin by some industries to combat Pediococcus contaminants is long-standing, yet knowledge about the resistance of pediococci to antimicrobial agents is minimal. Here we examined Pediococcus isolates to determine whether antibiotic resistance is associated with resistance to hops, presence of genes known to correlate with beer spoilage, or with ability to grow in beer. Results Lactic acid bacteria susceptibility test broth medium (LSM used in combination with commercially available GPN3F antimicrobial susceptibility plates was an effective method for assessing antimicrobial susceptibility of Pediococcus isolates. We report the finding of Vancomycin-susceptible Pediococcus isolates from four species. Interestingly, we found that hop-resistant, beer-spoilage, and beer-spoilage gene-harbouring isolates had a tendency to be more susceptible, rather than more resistant, to antimicrobial compounds. Conclusion Our findings indicate that the mechanisms involved in conferring hop-resistance or ability to spoil beer by Pediococcus isolates are not associated with resistance to antibiotics commonly used for treatment of human infections. Also, Vancomycin-resistance was found to be isolate-specific and not intrinsic to the genus as previously believed.

  1. 3-D electrical resistivity tomography using adaptive wavelet parameter grids

    Science.gov (United States)

    Plattner, A.; Maurer, H. R.; Vorloeper, J.; Blome, M.

    2012-04-01

    We present a novel adaptive model parametrization strategy for the 3-D electrical resistivity tomography problem and demonstrate its capabilities with a series of numerical examples. In contrast to traditional parametrization schemes, which are based on fixed disjoint blocks, we discretize the subsurface in terms of Haar wavelets and adaptively adjust the parametrization as the iterative inversion proceeds. This results in a favourable balance of cell sizes and parameter reliability, that is, in regions where the data constrain the subsurface properties well, our parametrization strategy leads to a fine grid, whereas poorly resolved areas are represented only by a few large blocks. This is documented with eigenvalue analyses and by computing model resolution matrices. During the initial iteration steps, only a few model parameters are involved, which reduces the risk that the regularization dominates the inversion. The algorithm also automatically accounts for non-linear effects caused by pronounced conductivity contrasts. Inside conductive features a finer grid is generated than inside more resistive structures. The automated parameter adaptation is computationally efficient, because the coarsening and refinement subroutines have a nearly linear numerical complexity with respect to the number of model parameters. Because our approach is not tightly coupled to electrical resistivity tomography, it should be straightforward to adapt it to other data types.

  2. Electrical resistivity tomography to delineate greenhouse soil variability

    Science.gov (United States)

    Rossi, R.; Amato, M.; Bitella, G.; Bochicchio, R.

    2013-03-01

    Appropriate management of soil spatial variability is an important tool for optimizing farming inputs, with the result of yield increase and reduction of the environmental impact in field crops. Under greenhouses, several factors such as non-uniform irrigation and localized soil compaction can severely affect yield and quality. Additionally, if soil spatial variability is not taken into account, yield deficiencies are often compensated by extra-volumes of crop inputs; as a result, over-irrigation and overfertilization in some parts of the field may occur. Technology for spatially sound management of greenhouse crops is therefore needed to increase yield and quality and to address sustainability. In this experiment, 2D-electrical resistivity tomography was used as an exploratory tool to characterize greenhouse soil variability and its relations to wild rocket yield. Soil resistivity well matched biomass variation (R2=0.70), and was linked to differences in soil bulk density (R2=0.90), and clay content (R2=0.77). Electrical resistivity tomography shows a great potential in horticulture where there is a growing demand of sustainability coupled with the necessity of stabilizing yield and product quality.

  3. Characterization of methicillin-resistant and -susceptible staphylococcal isolates from bovine milk in northwestern china.

    Directory of Open Access Journals (Sweden)

    Longping Li

    Full Text Available Emergence of methicillin-resistant Staphylococcus aureus (MRSA and methicillin-resistant coagulase-negative staphylococci (MR-CoNS in bovine milk is a major public health concern. The primary purpose of this research was to determine molecular genetic characteristics and antibiotic resistance of staphylococcal isolates recovered from milk of mastitic cows in the Shaanxi Province in Northwestern China. One hundred and thirteen methicillin-susceptible Staphylococcus aureus (MSSA, one mecA-positive and phenotype-positive MRSA, seven mecA- and mecC- negative but phenotype-positive MRSA and two MR-CoNS including one oxacillin-susceptible mecA-positive Staphylococcus haemolyticus (OS-MRSH and one mecA-positive and methicillin-resistant Staphylococcus epidermidis (MRSE isolates were recovered from 214 quarter milk samples on 4 dairy farms. All above 123 isolates were subjected to antibiotic resistance profiling. S. aureus isolates were also genotyped using the spa typing and the multilocus sequence typing (MLST. Eight MRSA and 2 MR-CoNS isolates were additionally tested for SCCmec types. Resistance was common among isolates against ampicillin or penicillin (80.5%, kanamycin (68.3%, gentamicin (67.5%, tetracycline (43.9% and chloramphenicol (30.1%. However, no isolate was resistant to vancomycin or teicoplanin. Twenty, 29 and 58 isolates showed resistance to 1, 2 or more than 2 antibiotics, respectively. The predominant multidrug resistance profile was penicillin/ampicillin/kanamycin/gentamicin/tetracycline (46 isolates. Most S. aureus isolates belonged to spa types t524 (n = 63, t11772 (a new type, n = 31 and t4207 (n = 15. At the same time, MLST types ST71 (n = 67 and ST2738 (a new type, n = 45 were identified as dominant sequence types. The mecA-positive and phenotype-positive MRSA isolate had a composite genotype t524-ST71-SCCmecIVa, while 7 mecA-negative but phenotype-positive MRSA isolates were all t524-ST71. The OS-MRSH isolate contained a type V

  4. Dental plaque bacteria with reduced susceptibility to chlorhexidine are multidrug resistant.

    Science.gov (United States)

    Saleem, Hafiz Ghulam Murtaza; Seers, Christine Ann; Sabri, Anjum Nasim; Reynolds, Eric Charles

    2016-09-15

    Chlorhexidine (CHX) is used in oral care products to help control dental plaque. In this study dental plaque bacteria were grown on media containing 2 μg/ml chlorhexidine gluconate to screen for bacteria with reduced CHX susceptibility. The isolates were characterized by 16S rRNA gene sequencing and antibiotic resistance profiles were determined using the disc diffusion method. The isolates were variably resistant to multiple drugs including ampicillin, kanamycin, gentamicin and tetracycline. Two species, Chryseobacterium culicis and Chryseobacterium indologenes were able to grow planktonically and form biofilms in the presence of 32 μg/ml CHX. In the CHX and multidrug resistant C. indologenes we demonstrated a 19-fold up-regulation of expression of the HlyD-like periplasmic adaptor protein of a tripartite efflux pump upon exposure to 16 μg/ml CHX suggesting that multidrug resistance may be mediated by this system. Exposure of biofilms of these resistant species to undiluted commercial CHX mouthwash for intervals from 5 to 60 s indicated that the mouthwash was unlikely to eliminate them from dental plaque in vivo. The study highlights the requirement for increased vigilance of the presence of multidrug resistant bacteria in dental plaque and raises a potential risk of long-term use of oral care products containing antimicrobial agents for the control of dental plaque.

  5. Evaluation of the Electrical Resistance and Capacitance of a Di-Electric Electro-Active Polymer

    Science.gov (United States)

    Ng, Boon Chai; Lovhoiden, Gunnar; Magbanua, James

    Dielectric Electro Active Polymers (DEAP) have the potential of converting mechanical energy into electrical energy. DEAP consists of a silicone dielectric film material with a special corrugated surface and a very thin layer of metallic electrodes on both sides of the surface allowing for large mechanical deformations with low operating forces. This work examined how the DEAP capacitance and the electrode resistance were affected by repeated stress relaxation cycles.

  6. Global Phenotypic Characterization of Effects of Fluoroquinolone Resistance Selection on the Metabolic Activities and Drug Susceptibilities of Clostridium perfringens Strains

    Directory of Open Access Journals (Sweden)

    Miseon Park

    2014-01-01

    Full Text Available Fluoroquinolone resistance affects toxin production of Clostridium perfringens strains differently. To investigate the effect of fluoroquinolone resistance selection on global changes in metabolic activities and drug susceptibilities, four C. perfringens strains and their norfloxacin-, ciprofloxacin-, and gatifloxacin-resistant mutants were compared in nearly 2000 assays, using phenotype microarray plates. Variations among mutant strains resulting from resistance selection were observed in all aspects of metabolism. Carbon utilization, pH range, osmotic tolerance, and chemical sensitivity of resistant strains were affected differently in the resistant mutants depending on both the bacterial genotype and the fluoroquinolone to which the bacterium was resistant. The susceptibilities to gentamicin and erythromycin of all resistant mutants except one increased, but some resistant strains were less susceptible to amoxicillin, cefoxitin, ceftriaxone, chloramphenicol, and metronidazole than their wild types. Sensitivity to ethidium bromide decreased in some resistant mutants and increased in others. Microarray analysis of two gatifloxacin-resistant mutants showed changes in metabolic activities that were correlated with altered expression of various genes. Both the chemical structures of fluoroquinolones and the genomic makeup of the wild types influenced the changes found in resistant mutants, which may explain some inconsistent reports of the effects of therapeutic use of fluoroquinolones on clinical isolates of bacteria.

  7. Three-way interactions among ectomycorrhizal mutualists, scale insects, and resistant and susceptible pinyon pines

    Energy Technology Data Exchange (ETDEWEB)

    Gehring, C.A.; Cobb, N.S.; Whitham, T.G. [Northern Arizona Univ., Flagstaff, AZ (United States)

    1997-05-01

    Herbivores and mycorrhizal fungi are important associates of most plants, but little is known about how these organisms interact. In a 9-yr experiment, we examined how the pinyon needle scale (Matsucoccus acalyptus) affects and is affected by the ectomycorrhizal mutualists found on the roots of scale-resistant and -susceptible pinyon pines (Pinus edulis). Three major results emerged. First, removal experiments demonstrated that scales negatively affected ectomycorrhiza. Second, although ectomycorrhiza could either positively or negatively influence scale performance by improving plant vigor or increasing plant investment in antiherbivore defenses, we found no ectomycorrhizal effect on scale mortality when we experimentally enhanced levels of ectomycorrhiza. This represented the first test of whether ectomycorrhiza promote plant resistance and contrasted with studies showing that arbuscular mycorrhiza negatively affected herbivores. Third, pinyon resistance to scales mediated the asymmetrical interaction between fungal mutualists and scale herbivores. High scale densities suppressed ectomycorrhizal colonization, but only on trees susceptible to scales. Similarities between mycorrhiza-herbivore interactions and competitive interactions among herbivores suggest broader generalities in the way aboveground herbivores interact with belowground plant associates. However, because mycorrhiza are mutualists, mycorrhiza-herbivore interactions do not fit within traditional competition paradigms. The widespread occurrence and importance of both herbivores and mycorrhiza argue for incorporating their interactions into ecological theory. 53 refs., 4 figs.

  8. BoLA-DRB3 gene polymorphism and FMD resistance or susceptibility in Wanbei cattle.

    Science.gov (United States)

    Lei, Wei; Liang, Qinglong; Jing, Luo; Wang, Chengmin; Wu, Xiaobing; He, Hongxuan

    2012-09-01

    For the further characterization of foot-and-mouth disease virus (FMDV)-induced foot-and-mouth disease, we investigated the association between polymorphism of BoLA-DRB3 gene and FMD resistance/susceptibility of Wanbei cattle challenged with FMDV. One hundred cattle were challenged with FMDV and exon 2 of BoLA-DRB3 genes was amplified by hemi-nested polymerase chain reaction from asymptomatic animals and from animals with FMD. PCR products were characterized by the RFLP technique using restriction enzymes Hae III. The results revealed extensive polymorphisms, 6 RFLP patterns were identified. By analyzing alleles and genotypic frequencies between healthy and infection with FMD cattle, we found that allele Hae III A was associated with susceptibility to FMD in Wanbei cattle (P FMD (P FMD. Hae IIICC and Hae III BC genotype were associated with resistance to FMD (P FMD (P < 0.01). Sequence analysis show that 89 amino acids were translated in exon 2 of BoLA-DRB3 and 13.70 % of nucleotide mutated, which resulted in 14.61 % of amino acid change. One PKC, one Tyr and one CAMP phosphorylation were increased; the hydrophobicity and secondary structure of proteins produced change after amino acid substitution. These results revealed that Wanbei cattle had the ability of resistance to disease by mutation which result changes of the protein structure to perform the regulation of the cell using different signaling pathways in the long process of choice evolution.

  9. Generic amyloidogenicity of mammalian prion proteins from species susceptible and resistant to prions.

    Science.gov (United States)

    Nyström, Sofie; Hammarström, Per

    2015-05-11

    Prion diseases are lethal, infectious diseases associated with prion protein (PrP) misfolding. A large number of mammals are susceptible to both sporadic and acquired prion diseases. Although PrP is highly conserved and ubiquitously expressed in all mammals, not all species exhibit prion disease. By employing full length recombinant PrP from five known prion susceptible species (human, cattle, cat, mouse and hamster) and two species considered to be prion resistant (pig and dog) the amyloidogenicity of these PrPs has been delineated. All the mammalian PrPs, even from resistant species, were swiftly converted from the native state to amyloid-like structure when subjected to a native condition conversion assay. The PrPs displayed amyloidotypic tinctorial and ultrastructural hallmarks. Self-seeded conversion of the PrPs displayed significantly decreased lag phases demonstrating that nucleation dependent polymerization is a dominating mechanism in the fibrillation process. Fibrils from Aβ1-40, Aβ1-42, Lysozyme, Insulin and Transthyretin did not accelerate conversion of HuPrP whereas fibrils from HuPrP90-231 and HuPrP121-231 as well as full length PrPs of all PrPs efficiently seeded conversion showing specificity of the assay requiring the C-terminal PrP sequence. Our findings have implications for PrP misfolding and could have ramifications in the context of prion resistant species and silent carriers.

  10. Electrical resistance measurements of connector-panel interfaces

    Science.gov (United States)

    Blomquist, Steven

    1990-05-01

    This report indicates construction methods which would assure both vacuum and electrical-grounding integrity of the subminiature series A (SMA) vacuum bulkhead feedthrough connectors. This investigation was initiated in response to the finding that some of the connectors on the nonupsettable computer modules were not thoroughly grounded. This report presents the results of resistivity measurements on several selected conducting panel materials and several configurations of feedthroughs. The information reported is organized into procedures used to acquire the data, test results, and recommendations. Specific recommendations are made for the best materials and parts to achieve low resistance and a hermetic seal. Also, designs are recommended for the O-ring and groove design on bulkhead hermetic feedthroughs.

  11. Activity of the antiseptic polyhexanide against meticillin-susceptible and meticillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Fabry, W; Reimer, C; Azem, T; Aepinus, C; Kock, H J; Vahlensieck, W

    2013-12-01

    Staphylococcus aureus is one of the most important pathogens, with increasing emergence of meticillin-resistant S. aureus (MRSA) strains. This is associated not only with multiresistance to antibiotics but also with increasing resistance to topical antibiotics and antiseptics. As the antiseptic polyhexanide has only a low risk of emergence of resistant strains, the aim of the study was to obtain data on the sensitivity of S. aureus towards polyhexanide. The effect of polyhexanide was tested against 80 meticillin-susceptible S. aureus (MSSA) and 80 MRSA strains from sporadic cases as well as against 6 MRSA outbreak strains. The clonal diversity of the 166 strains was proven by pulsed-field gel electrophoresis (PFGE). Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined by the serial broth microdilution technique according to DIN 58940. Time-kill studies were performed for reference strains MSSA ATCC 29213 and MRSA ATCC 33591. MICs and MBCs in the range of 0.5-2mg/L were found. According to a created epidemiological cut-off (ECOFF) value of 4mg/L, all strains were regarded as susceptible to polyhexanide, including MRSA epidemic strains and MSSA and MRSA sporadic strains with various antibiotic susceptibility patterns. Addition of up to 4% albumin to the test medium did not change the MICs and MBCs. Time-kill studies showed reduction rates of 4log10CFU/mL for 200mg/L and 5log10CFU/mL for 400mg/L polyhexanide within 5-30min. It is concluded that polyhexanide is suitable for topical eradication of S. aureus. Copyright © 2013 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

  12. Phenotypic and genotypic correlates of daptomycin-resistant methicillin-susceptible Staphylococcus aureus clinical isolates.

    Science.gov (United States)

    Kang, Kyoung-Mi; Mishra, Nagendra N; Park, Kun Taek; Lee, Gi-Yong; Park, Yong Ho; Bayer, Arnold S; Yang, Soo-Jin

    2017-02-01

    Daptomycin (DAP) has potent activity in vitro and in vivo against both methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains. DAP-resistance (DAP-R) in S. aureus has been mainly observed in MRSA strains, and has been linked to single nucleotide polymorphisms (SNPs) within the mprF gene leading to altered cell membrane (CM) phospholipid (PL) profiles, enhanced positive surface charge, and changes in CM fluidity. The current study was designed to delineate whether these same genotypic and phenotypic perturbations are demonstrated in clinically-derived DAP-R MSSA strains. We used three isogenic DAP-susceptible (DAP-S)/DAP-R strainpairs and compared: (i) presence of mprF SNPs, (ii) temporal expression profiles of the two key determinants (mprF and dltABCD) of net positive surface charge, (iii) increased production of mprF-dependent lysinylated-phosphatidylglycerol (L-PG), (iv) positive surface charge assays, and (v) susceptibility to cationic host defense peptides (HDPs) of neutrophil and platelet origins. Similar to prior data in MRSA, DAP-R (vs DAP-S) MSSA strains exhibited hallmark hot-spot SNPs in mprF, enhanced and dysregulated expression of both mprF and dltA, L-PG overproduction, HDP resistance and enhanced positive surface charge profiles. However, in contrast to most DAP-R MRSA strains, there were no changes in CM fluidity seen. Thus, charge repulsion via mprF-and dlt-mediated enhancement of positive surface charge may be the main mechanism to explain DAP-R in MSSA strains.

  13. Sensitivity of leachate and fine contents on electrical resistivity variations of sandy soils.

    Science.gov (United States)

    Yoon, G L; Park, J B

    2001-06-29

    Laboratory pilot tests were performed to investigate the relationship between electrical resistivity and contaminated soil properties. Three different sandy soils and leachate collected from one of the industrial waste landfill sites in Korea were mixed to simulate contaminated soil conditions. The values of electrical resistivity of the soils were measured using laboratory scaled resistivity cone penetrometer probe. In the experiments, electrical resistivity was observed in terms of water content, unit weight, saturation degree of the soils, and leachate concentration. The experimental results show that the electrical resistivity of the sandy soils depends largely on the water content and electrical properties of pore water rather than unit weight and types of soils. The amount of fines can have significant effect on electrical properties of soils. Direct correlation with contamination in such soils may not be valid here. The results suggest that the electrical resistivity measurement is well suited and applicable for monitoring and delineation of contaminants in the subsurface.

  14. Antibiotic susceptibility of coagulase-negative staphylococci (CoNS): emergence of teicoplanin-non-susceptible CoNS strains with inducible resistance to vancomycin.

    Science.gov (United States)

    Ma, Xiao Xue; Wang, En Hua; Liu, Yong; Luo, En Jie

    2011-11-01

    Coagulase-negative staphylococci (CoNS) have become increasingly recognized as important agents of nosocomial infection. One of the characteristics of CoNS is their resistance to multiple antimicrobial agents commonly used for the treatment of staphylococcal infections. CoNS strains (n = 745) isolated from a university teaching hospital in China between 2004 and 2009 were tested for antibiotic resistance. The antibiotics were placed into three categories based on resistance levels of the CoNS strains to these antibiotics: high resistance (resistance rate >70 %), including penicillin G, oxacillin and erythromycin; medium resistance (resistance rate between 30 and 70 %), including tetracycline, clindamycin, ciprofloxacin, trimethoprim/sulfamethoxazole and chloramphenicol; and low resistance (resistance rate teicoplanin increased from 4.5 to 6.7 % between 2008 and 2009. A one-step vancomycin agar selection experiment and subsequent population analysis revealed potentially vancomycin-resistant subpopulations that have been selected from the teicoplanin-non-susceptible strains. Vigilant surveillance of nosocomial isolates of CoNS is needed to determine their resistance to glycopeptides.

  15. Terpene Profile, Leaf Anatomy, and Enzyme Activity of Resistant and Susceptible Cocoa Clonesto Vascular Streak Dieback Disease

    Directory of Open Access Journals (Sweden)

    Adi Prawoto

    2014-10-01

    Full Text Available Vascular-streak dieback (VSD, Oncobasidium theobromae is the most prevalent disease of Theobroma cacao L. in Indonesia. This study aims to analyze resistance mechanism to VSD based on terpene profile, leaf anatomy, chitinase, and peroxidase study. Resistant clones of Sulawesi 1 and Sca 6 and susceptible clones of ICS 60 and TSH 858 were used for terpene profile, leaf anatomy analysis, chitinase, peroxides, polyphenol, lignin, and cellulose analysis. Those clones and KEE 2, KKM 22 and ICS 13 were used for peroxides analysis. For trichome study, the resistant clones of Sulawesi 1, Sca 6, KEE 2, and KKM 22, and susceptible clones of ICS 60 and TSH 858 were used. GCMS analysis showed that chromatogram pattern of resistant and susceptible groups were quite similar, but resistant clones contained 22% more components than the susceptible ones. Resistant clones contained groups of pinene, decane, myrcene, and octadecanoic acid, while those substances on usceptible clones were absent. Trichome was thicker on younger leaf, and its density on the basal was higher than that on the middle and tip leaf parts. Trichome density of resistant clone was not always thicker than that of susceptible ones. On resistant clones, stomatal density was lower and width of stomate pits was narrower, while thickness of epidermis layer and pallisade parenchym were higher. Polyphenol content of resistant clones were higher but lignin and cellulose of both groups were similar. Chitinase activity which has a role in hydrolysis of mycelia cell wall was higher on the resistant clones, but peroxides which has a role in polymeration of lignin biosynthesis was similar between both groups. It is concluded that groups of terpene pinene, decane, myrcene, and octadecanoic acid, thickness of leaf epidermis, density and width of stomata pit, and chitinase activity plays important role in cocoa resistance to VSD. Key words: Theobroma cacaoL., clone, vascular-streak dieback, resistance, leaf

  16. Efficient recovery of fluoroquinolone-susceptible and fluoroquinolone-resistant Escherichia coli strains from frozen samples.

    Science.gov (United States)

    Lautenbach, Ebbing; Santana, Evelyn; Lee, Abby; Tolomeo, Pam; Black, Nicole; Babson, Andrew; Perencevich, Eli N; Harris, Anthony D; Smith, Catherine A; Maslow, Joel

    2008-04-01

    We assessed the rate of recovery of fluoroquinolone-resistant and fluoroquinolone-susceptible Escherichia coli isolates from culture of frozen perirectal swab samples compared with the results for culture of the same specimen before freezing. Recovery rates for these 2 classes of E. coli were 91% and 83%, respectively. The majority of distinct strains recovered from the initial sample were also recovered from the frozen sample. The strains that were not recovered were typically present only in low numbers in the initial sample. These findings emphasize the utility of frozen surveillance samples.

  17. Methicillin-resistant Staphylococcus aureus prevalence: Current susceptibility patterns in Trinidad

    Directory of Open Access Journals (Sweden)

    Land Michael

    2006-05-01

    Full Text Available Abstract Background Methicillin-resistant Staphylococcus aureus (MRSA has become one of the most widespread causes of nosocomial infections worldwide. Recently, reports have emerged that S. aureus strains recovered from community-acquired infections are also methicillin-resistant. This study was undertaken to analyze the prevalence of methicillin resistance among isolates at a regional hospital in Trinidad, and document the current resistance profile of MRSA and methicillin-sensitive Staphylococcus aureus (MSSA to the commonly used anti-staphylococcal agents. Methods Over a 6-year period we analyzed 2430 isolates of S. aureus strains recovered from various clinical sources, from hospital and community practices. Antimicrobial susceptibility testing was done according to guideline recommendations of the National Committee for Clinical Laboratory Standards. Results The prevalence of MRSA from surgical/burn wounds, urine and pus/abscess were 60.1%, 15.5% and 6.6%, respectively. The major sources of MSSA were surgical/burn wounds, pus/abscess and upper respiratory tract specimens with rates of 32.9%, 17.1% and 14.3%, respectively. The greatest prevalence of resistance of MRSA was seen for erythromycin (86.7%, and clindamycin (75.3%. Resistance rates among MSSA were highest for ampicillin (70%. Resistance rates for tetracycline were similar among both MRSA (78.7% and MSSA (73.5%. The MRSA recovery rates from nosocomial sources (20.8% was significantly higher than that of previous years (12.5% (p Conclusion The prevalence of MRSA in the hospital increased from 12.5% in 1999 to 20.8% in 2004. Most isolates were associated with infected surgical/burn wounds which may have become infected via the hands of HCPs during dressing exercises. Infection control measures aimed at the proper hand hygiene procedures may interrupt the spread of MRSA. HCPs may also be carriers of MRSA in their anterior nares. Surveillance cultures of both patients and HCPs may help

  18. Efficacy of an insecticide paint against insecticide-susceptible and resistant mosquitoes - Part 1: Laboratory evaluation

    Directory of Open Access Journals (Sweden)

    Carnevale Pierre

    2010-11-01

    Full Text Available Abstract Background The main malaria vector Anopheles gambiae and the urban pest nuisance Culex quinquefasciatus are increasingly resistant to pyrethroids in many African countries. There is a need for new products and strategies. Insecticide paint Inesfly 5A IGR™, containing two organophosphates (OPs, chlorpyrifos and diazinon, and insect growth regulator (IGR, pyriproxyfen, was tested under laboratory conditions for 12 months following WHOPES Phase I procedures. Methods Mosquitoes used were laboratory strains of Cx. quinquefasciatus susceptible and resistant to OPs. The paint was applied at two different doses (1 kg/6 m2 and 1 kg/12 m2 on different commonly used surfaces: porous (cement and stucco and non-porous (softwood and hard plastic. Insecticide efficacy was studied in terms of delayed mortality using 30-minute WHO bioassay cones. IGR efficacy on fecundity, fertility and larval development was studied on OP-resistant females exposed for 30 minutes to cement treated and control surfaces. Results After treatment, delayed mortality was high (87-100% even against OP-resistant females on all surfaces except cement treated at 1 kg/12 m2. Remarkably, one year after treatment delayed mortality was 93-100% against OP-resistant females on non-porous surfaces at both doses. On cement, death rates were low 12 months after treatment regardless of the dose and the resistance status. Fecundity, fertility and adult emergence were reduced after treatment even at the lower dose (p -3. A reduction in fecundity was still observed nine months after treatment at both doses (p -3 and adult emergence was reduced at the higher dose (p -3. Conclusions High mortality rates were observed against laboratory strains of the pest mosquito Cx. quinquefasciatus susceptible and resistant to insecticides. Long-term killing remained equally important on non-porous surfaces regardless the resistance status for over 12 months. The paint's effect on fecundity, fertility and

  19. On the use of electrical resistivity methods in monitoring infiltration of ...

    African Journals Online (AJOL)

    Since changes in moisture and salt concentrations usually provide contrasts in electrical properties against the host media, electrical resistivity methods can be used to monitor ingression of solute plumes as well as to detect any preferential flow paths within the ash medium. In this study, 2D electrical resistivity tomography ...

  20. Susceptibility of methicillin-resistant Staphylococcus aureus and enterococci to teicoplanin in Pakistan: the MRSET study.

    Science.gov (United States)

    Ahmed, Altaf; Hussain, Shagufta; Ijaz, Tayyaba; Hashemy, Irfan

    2014-03-01

    To evaluate the susceptibility pattern of S. aureus and enterococci to teicoplanin using an in vitro method. Between February and November 2011, valid bacteriological samples were collected at three hospitals in three cities in Pakistan and the organism was isolated. Only samples containing S. aureus or enterococci were tested for their sensitivity to teicoplanin and various other standard antimicrobials in therapy, using the disc diffusion testing by the Kirby-Bauer method. SPSS 18 was used for statistical analysis. Of the 401 isolates collected, a majority 293 (59.6%) were methicillin-sensitive S. aureus, while 136 (33.9%) were methicillin-resistant S. aureus; and 26 (6.5%) were enterococci. All isolates were sensitive to teicoplanin and vancomycin. Teicoplanin had the same in vitro sensitivity as vancomycin against methicillin-sensitive S. aureus, methicillin-resistant S. aureus and enterococci in clinical isolates.

  1. Identification of genes differentially expressed during interaction of resistant and susceptible apple cultivars (Malus x domestica) with Erwinia amylovora.

    Science.gov (United States)

    Baldo, Angela; Norelli, Jay L; Farrell, Robert E; Bassett, Carole L; Aldwinckle, Herb S; Malnoy, Malnoy

    2010-01-04

    The necrogenic enterobacterium, Erwinia amylovora is the causal agent of the fire blight (FB) disease in many Rosaceae species, including apple and pear. During the infection process, the bacteria induce an oxidative stress response with kinetics similar to those induced in an incompatible bacteria-plant interaction. No resistance mechanism to E. amylovora in host plants has yet been characterized, recent work has identified some molecular events which occur in resistant and/or susceptible host interaction with E. amylovora: In order to understand the mechanisms that characterize responses to FB, differentially expressed genes were identified by cDNA-AFLP analysis in resistant and susceptible apple genotypes after inoculation with E. amylovora. cDNA were isolated from M.26 (susceptible) and G.41 (resistant) apple tissues collected 2 h and 48 h after challenge with a virulent E. amylovora strain or mock (buffer) inoculated. To identify differentially expressed transcripts, electrophoretic banding patterns were obtained from cDNAs. In the AFLP experiments, M.26 and G.41 showed different patterns of expression, including genes specifically induced, not induced, or repressed by E. amylovora. In total, 190 ESTs differentially expressed between M.26 and G.41 were identified using 42 pairs of AFLP primers. cDNA-AFLP analysis of global EST expression in a resistant and a susceptible apple genotype identified different major classes of genes. EST sequencing data showed that genes linked to resistance, encoding proteins involved in recognition, signaling, defense and apoptosis, were modulated by E. amylovora in its host plant. The expression time course of some of these ESTs selected via a bioinformatic analysis has been characterized. These data are being used to develop hypotheses of resistance or susceptibility mechanisms in Malus to E. amylovora and provide an initial categorization of genes possibly involved in recognition events, early signaling responses the

  2. In vivo activity of Sapindus saponaria against azole-susceptible and -resistant human vaginal Candida species

    Directory of Open Access Journals (Sweden)

    Svidzinski Terezinha IE

    2011-05-01

    Full Text Available Abstract Background Study of in vivo antifungal activity of the hydroalcoholic extract (HE and n-BuOH extract (BUTE of Sapindus saponaria against azole-susceptible and -resistant human vaginal Candida spp. Methods The in vitro antifungal activity of HE, BUTE, fluconazole (FLU, and itraconazole (ITRA was determined by the broth microdilution method. We obtained values of minimal inhibitory concentration (MIC and minimum fungicide concentration (MFC for 46 strains of C. albicans and 10 of C. glabrata isolated from patients with vulvovaginal candidiasis (VVC. VVC was induced in hyperestrogenic Wistar rats with azole-susceptible C. albicans (SCA, azole-resistant C. albicans (RCA, and azole-resistant C. glabrata (RCG. The rats were treated intravaginally with 0.1 mL of HE or BUTE at concentrations of 1%, 2.5% and 5%; 100 μg/mL of FLU (treatment positive control; or distilled water (negative control at 1, 24, and 48 h after induction of the infection, and the progress of VVC was monitored by culturing and scanning electron microscopy (SEM. The toxicity was evaluated in cervical cells of the HeLa cell line. Results The extracts showed in vitro inhibitory and fungicidal activity against all the isolates, and the MIC and MFC values for the C. glabrata isolates were slightly higher. In vivo, the SCA, RCA, and RCG infections were eliminated by 21 days post-infection, with up to 5% HE and BUTE, comparable to the activity of FLU. No cytotoxic action was observed for either extract. Conclusions Our results demonstrated that HE and BUTE from S. saponaria show inhibitory and fungicidal activity in vitro, in addition to in vivo activity against azole-resistant vaginal isolates of C. glabrata and azole-susceptible and resistant isolates of C. albicans. Also considering the lack of cytotoxicity and the low concentrations of the extracts necessary to eliminate the infection in vivo, HE and BUTE show promise for continued studies with purified antifungal substances

  3. Genetic profiles of ten Dirofilaria immitis isolates susceptible or resistant to macrocyclic lactone heartworm preventives

    Directory of Open Access Journals (Sweden)

    Catherine Bourguinat

    2017-11-01

    Full Text Available Abstract Background For dogs and cats, chemoprophylaxis with macrocyclic lactone (ML preventives for heartworm disease is widely used in the United States and other countries. Since 2005, cases of loss of efficacy (LOE of heartworm preventives have been reported in the U.S. More recently, ML-resistant D. immitis isolates were confirmed. Previous work identified 42 genetic markers that could predict ML response in individual samples. For field surveillance, it would be more appropriate to work on microfilarial pools from individual dogs with a smaller subset of genetic markers. Methods MiSeq technology was used to identify allele frequencies with the 42 genetic markers previously reported. Microfilaria from ten well-characterized new isolates called ZoeKY, ZoeMI, ZoeGCFL, ZoeAL, ZoeMP3, ZoeMO, ZoeAMAL, ZoeLA, ZoeJYD-34, and Metairie were extracted from fresh blood from dogs. DNA were extracted and sequenced with MiSeq technology. Allele frequencies were calculated and compared with the previously reported susceptible, LOE, and resistant D. immitis populations. Results The allele frequencies identified in the current resistant and susceptible isolates were in accordance with the allele frequencies previously reported in related phenotypes. The ZoeMO population, a subset of the ZoeJYD-34 population, showed a genetic profile that was consistent with some reversion towards susceptibility compared with the parental ZoeJYD-34 population. The Random Forest algorithm was used to create a predictive model using different SNPs. The model with a combination of three SNPs (NODE_42411_RC, NODE_21554_RC, and NODE_45689 appears to be suitable for future monitoring. Conclusions MiSeq technology provided a suitable methodology to work with the microfilarial samples. The list of SNPs that showed good predictability for ML resistance was narrowed. Additional phenotypically well characterized D. immitis isolates are required to finalize the best set of SNPs to be

  4. Improvement of electrical resistivity tomography for leachate injection monitoring.

    Science.gov (United States)

    Clément, R; Descloitres, M; Günther, T; Oxarango, L; Morra, C; Laurent, J-P; Gourc, J-P

    2010-03-01

    Leachate recirculation is a key process in the scope of operating municipal waste landfills as bioreactors, which aims to increase the moisture content to optimize the biodegradation in landfills. Given that liquid flows exhibit a complex behaviour in very heterogeneous porous media, in situ monitoring methods are required. Surface time-lapse electrical resistivity tomography (ERT) is usually proposed. Using numerical modelling with typical 2D and 3D injection plume patterns and 2D and 3D inversion codes, we show that wrong changes of resistivity can be calculated at depth if standard parameters are used for time-lapse ERT inversion. Major artefacts typically exhibit significant increases of resistivity (more than +30%) which can be misinterpreted as gas migration within the waste. In order to eliminate these artefacts, we tested an advanced time-lapse ERT procedure that includes (i) two advanced inversion tools and (ii) two alternative array geometries. The first advanced tool uses invariant regions in the model. The second advanced tool uses an inversion with a "minimum length" constraint. The alternative arrays focus on (i) a pole-dipole array (2D case), and (ii) a star array (3D case). The results show that these two advanced inversion tools and the two alternative arrays remove almost completely the artefacts within +/-5% both for 2D and 3D situations. As a field application, time-lapse ERT is applied using the star array during a 3D leachate injection in a non-hazardous municipal waste landfill. To evaluate the robustness of the two advanced tools, a synthetic model including both true decrease and increase of resistivity is built. The advanced time-lapse ERT procedure eliminates unwanted artefacts, while keeping a satisfactory image of true resistivity variations. This study demonstrates that significant and robust improvements can be obtained for time-lapse ERT monitoring of leachate recirculation in waste landfills. Copyright 2009 Elsevier Ltd. All rights

  5. Wounding induces local resistance but systemic susceptibility to Botrytis cinerea in pepper plants.

    Science.gov (United States)

    García, Tania; Gutiérrez, Jorge; Veloso, Javier; Gago-Fuentes, Raquel; Díaz, José

    2015-03-15

    Cotyledon wounding in pepper caused the early generation of hydrogen peroxide both locally (cotyledons) and systemically (upper true leaves). However, 72 h later there is a different wound response between local and systemic organs, as shown by resistance to the pathogenic fungus Botrytis cinerea, that increased locally and decreased systemically. Signaling by ethylene and jasmonic acid was assessed by using two inhibitors: 1-methylcyclopropene (MCP, inhibitor of ethylene receptors) and ibuprofen (inhibitor of jasmonate biosynthesis). MCP did not affect the modulation of resistance levels to Botrytis by wounding, ruling out the involvement of ethylene signaling. Ibuprofen did not inhibit wound-induced resistance at the local level, but inhibited wound-induced systemic susceptibility. Moreover, changes of biochemical and structural defenses in response to wounding were studied. Peroxidase activity and the expression of a peroxidase gene (CAPO1) increased locally as a response to wounding, but no changes were observed systemically. Lignin deposition was induced in wounded cotyledons, but was repressed in systemic leaves of wounded plants, whereas soluble phenolics did not change locally and decreased systemically. The expression of two other genes involved in plant defense (CABPR1 and CASC1) was also differentially regulated locally and systemically, pointing to a generalized increase in plant defenses at the local level and a systemic decrease as a response to wounding. Wound-induced defenses at the local level coincided with resistance to the necrotroph fungus B. cinerea, whereas depleted defenses in systemic leaves of wounded plants correlated to induced susceptibility against this pathogen. It may be that the local response acts as a sink of energy resources to mount a defense against pathogens, whereas in systemic organs the resources for defense are lower. Copyright © 2015 Elsevier GmbH. All rights reserved.

  6. Miltefosine-resistant Leishmania infantum strains with an impaired MT/ROS3 transporter complex retain amphotericin B susceptibility.

    Science.gov (United States)

    Mondelaers, Annelies; Hendrickx, Sarah; Van Bockstal, Lieselotte; Maes, Louis; Caljon, Guy

    2018-02-01

    Increasing numbers of miltefosine treatment failures in visceral leishmaniasis therapy and reports of miltefosine resistance in the Indian subcontinent resulted in the recommendation to use liposomal amphotericin B as first-line therapy. Cross-resistance between miltefosine and amphotericin B has recently been documented, suggesting a role of mutations in the miltefosine transporter, a complex encoded by the MT and ROS3 genes. This study aimed to further explore the putative role of MT/ROS3 defects in the molecular basis of amphotericin B cross-resistance. The susceptibility profiles of different miltefosine-resistant Leishmania infantum strains with well-characterized mutations in the transporter complex and the corresponding episomally restored susceptible parasite lines were determined using both the routine extracellular promastigote assay and the intracellular amastigote assay. In vitro amastigote and promastigote susceptibility testing of the two miltefosine-resistant and the episomally reconstituted L. infantum lines revealed full susceptibility to amphotericin B, despite the variable miltefosine susceptibility profile. Mutations present in either the MT and/or ROS3 gene are not sufficient to elicit higher tolerance to amphotericin B. Additional synergistic adaptations may be responsible for the miltefosine/amphotericin B cross-resistance described earlier.

  7. Genetic and sexual separation between insect resistant and susceptible Barbarea vulgaris plants in Denmark

    DEFF Research Database (Denmark)

    Toneatto, Fiorello; Nielsen, Jens Kvist; Ørgaard, Marian

    2010-01-01

    . In the cruciferous plant Barbarea vulgaris, some Danish individuals are resistant to herbivory by flea beetles (Phyllotreta nemorum), whereas others are not. The flea beetles are, in parallel, either resistant or susceptible to the plants defenses. To understand the historical-evolutionary framework...... was determined by analysis of molecular markers. Resistant and susceptible Danish plants were genetically strongly differentiated and produced significantly fewer hybrids than expected from random mating or nearest neighbour mating. Our results suggest that the two types belong to different evolutionary lineages...

  8. Evaluation of automated systems for aminoglycosides and fluoroquinolones susceptibility testing for Carbapenem-resistant Enterobacteriaceae

    Directory of Open Access Journals (Sweden)

    Zhichang Zhao

    2017-08-01

    Full Text Available Abstract Background Automated systems (MicroScan WalkAway 96 Plus, Phoenix 100, and Vitek 2 Compact are widely used in clinical laboratories nowadays. The aim of this study is to evaluate the performance of these three systems for susceptibility testing of aminoglycosides and fluoroquinolones against Carbapenem-resistant Enterobacteriaceae (CRE. Methods A total of 75 CRE isolates were used in this study. Quinolone resistance determinants (QRDs (qnrA, qnrB, qnrC, qnrD, qnrS, aac(6′-Ib-cr, oqxAB and qepA and aminoglycoside resistance determinants (ARDs (aac(6′-Ib, armA, npmA, rmtA, rmtB, rmtC, rmtD and rmtE of these CRE were screened by PCR. The MICs of aminoglycosides (gentamicin and amikacin and fluoroquinolones (ciprofloxacin and levofloxacin to CRE obtained with the automated systems were compared with the reference method (agar dilution method. Results Totally, 97.3% (73/75 of CRE harbored QRDs. The qnr gene was the most common QRD determinant identified in 68 (96.7%, followed by aac (6′-Ib-cr in 56 (74.7%, oqxAB in 23 (30.7%, and qepA in 2 (2.7%, respectively. 22.7% (17/75 of CRE harbored ARD determinants. rmtA, rmtB and npmA were identified among these isolates in 6 (8.0%, 6 (8.0% and 5 (6.7%, respectively. A total of 900 results were obtained in this study. Overall, the total error rate was 9.89%. Twenty-eight very major errors (3.11%, 22 major errors (2.44% and 39 minor errors (4.33% were identified against agar dilution method. The very major errors were almost evenly distributed between results for fluoroquinolones (2.89% and aminoglycosides (3.33%, while the major errors and minor errors were more commonly found in the results of fluoroquinolones (3.11% and 6.44%, respectively than aminoglycosides (1.78% and 2.22%, respectively. Conclusions Our study shows that testing difficulties in susceptibility testing do exist in automated systems. We suggest clinical laboratories using automated systems should consider using a second

  9. Fault mechanism analysis and simulation for continuity resistance test of electrical components in aircraft engine

    Science.gov (United States)

    Shi, Xudong; Yin, Yaping; Wang, Jialin; Sun, Zhaorong

    2017-01-01

    A large number of electrical components are used in civil aircraft engines, whose electrical circuits are usually intricate and complicated. Continuity resistance is an important parameter for the operating state of electrical components. Electrical continuity fault has serious impact on the reliability of the aircraft engine. In this paper, mathematical models of electrical components are established, and simulation is made by Simulink to analyze the electrical continuity fault.

  10. The Aspergillus fumigatus Damage Resistance Protein Family Coordinately Regulates Ergosterol Biosynthesis and Azole Susceptibility

    Directory of Open Access Journals (Sweden)

    Jinxing Song

    2016-02-01

    Full Text Available Ergosterol is a major and specific component of the fungal plasma membrane, and thus, the cytochrome P450 enzymes (Erg proteins that catalyze ergosterol synthesis have been selected as valuable targets of azole antifungals. However, the opportunistic pathogen Aspergillus fumigatus has developed worldwide resistance to azoles largely through mutations in the cytochrome P450 enzyme Cyp51 (Erg11. In this study, we demonstrate that a cytochrome b5-like heme-binding damage resistance protein (Dap family, comprised of DapA, DapB, and DapC, coordinately regulates the functionality of cytochrome P450 enzymes Erg5 and Erg11 and oppositely affects susceptibility to azoles. The expression of all three genes is induced in an azole concentration-dependent way, and the decreased susceptibility to azoles requires DapA stabilization of cytochrome P450 protein activity. In contrast, overexpression of DapB and DapC causes dysfunction of Erg5 and Erg11, resulting in abnormal accumulation of sterol intermediates and further accentuating the sensitivity of ΔdapA strains to azoles. The results of exogenous-hemin rescue and heme-binding-site mutagenesis experiments demonstrate that the heme binding of DapA contributes the decreased azole susceptibility, while DapB and -C are capable of reducing the activities of Erg5 and Erg11 through depletion of heme. In vivo data demonstrate that inactivated DapA combined with activated DapB yields an A. fumigatus mutant that is easily treatable with azoles in an immunocompromised mouse model of invasive pulmonary aspergillosis. Compared to the single Dap proteins found in Saccharomyces cerevisiae and Schizosaccharomyces pombe, we suggest that this complex Dap family regulatory system emerged during the evolution of fungi as an adaptive means to regulate ergosterol synthesis in response to environmental stimuli.

  11. Virulence factors of fluconazole-susceptible and fluconazole-resistant Candida albicans after antimicrobial photodynamic therapy.

    Science.gov (United States)

    Alves, Fernanda; de Oliveira Mima, Ewerton Garcia; Passador, Renata Caroline Polato; Bagnato, Vanderlei Salvador; Jorge, Janaína Habib; Pavarina, Ana Cláudia

    2017-05-01

    This study evaluated the effects of antimicrobial photodynamic therapy (aPDT) mediated by Photodithazine® (PDZ) and LED light on the virulence factors of fluconazole-susceptible (CaS) and fluconazole-resistant (CaR) Candida albicans. Standardized suspensions of strains were prepared (10 7 ), and after 48 h of biofilm formation, these strains were incubated with PDZ (100 mg/L) for 20 min and exposed to LED light (660 nm, 37.5 J/cm 2 ). Additional samples were treated with PDZ or light only, and the control consisted of biofilms that received no treatment. After aPDT, the cells were recovered and the virulence factors were evaluated. To analyze the capacity of adhesion, cells were recovered after aPDT and submitted to the adhesion process in the bottom of a 96-well plate. After this, metabolic activity tests (XTT assay) and cell viability (colony forming units per milliliter, CFU/mL) were applied. To evaluate the biofilm-forming ability after aPDT, the cells recovered were submitted to biofilm formation procedures, and the biofilm formed was evaluated by XTT, CFU/mL, and total biomass (crystal violet) tests. Lastly, the capacity for synthesizing protease and phospholipase enzymes after aPDT was evaluated by fluorimetric tests. Data were analyzed by two- or three-way ANOVA tests (p ≤ 0.05). It was verified that aPDT reduced the viability of both strains, fluconazole-susceptible and fluconazole-resistant C. albicans. It was also observed that the CaR strain had lower susceptibility to the aPDT when compared with the CaS strain. However, regarding the virulence factors evaluated, it was demonstrated that aPDT did not alter the adherence and biofilm formation ability and enzymatic production.

  12. Polymorphisms in drug-resistant-related genes shared among drug-resistant and pan-susceptible strains of sequence type 10, Beijing family of Mycobacterium tuberculosis

    Directory of Open Access Journals (Sweden)

    Sanjib Mani Regmi

    2015-01-01

    A sequence analysis was performed of 81 previously reported drug-resistant associated genes in multidrug-resistant and pan-susceptible strains of the Beijing family sequence type 10 of MTB. This analysis revealed 10 synonymous and 12 nonsynonymous single nucleotide polymorphisms (SNPs that are shared by all strains under study. One frameshift mutation was also observed to be common to all. These data might be useful in excluding some observed SNPs in drug-resistant-associated genes of MTB Beijing ST 10 when performing genotypic drug susceptibility assay.

  13. A Technique for Evaluating Heterodera glycines Development in Susceptible and Resistant Soybean.

    Science.gov (United States)

    Halbrendt, J M; Lewis, S A; Shipe, E R

    1992-03-01

    A technique was developed to evaluate Heterodera glycines development in susceptible and resistant soybean. Roots of 3-day-old soybean were exposed to infective juveniles of H. glyci.nes in sand for 8 hours followed by washing and transfer to hydroponic culture. The cotyledons and apical meristem were removed and plants were maintained under constant light, which resulted in a dwarfed plant system. After 15 or 20 days at 27 C, nematodes were rated for development. Emerged males were sieved from the culture water and females were counted directly from the roots. Nematodes remaining in the roots were rated for development after staining and clearing the tissues. The proportion of nematodes at each stage of development and the frequency of completed molts for each stage were calculated from these data. This technique showed that resistance to H. glycines was stage related and did not affect males and females equally in all resistant hosts. The resistance of plant introduction PI 209332 primarily affected development of third and fourth-stage juveniles; 'Pickett' mainly affected second and third-stage juveniles, whereas PI 89772 affected all stages. Male development was markedly affected in PI 89772 and 'Pickett' but not in PI 209332.

  14. Comparative proteomic analysis of antimony-resistant and -susceptible Leishmania braziliensis and Leishmania infantum chagasi lines.

    Science.gov (United States)

    Matrangolo, Fabiana S V; Liarte, Daniel B; Andrade, Laila C; de Melo, Melina F; Andrade, Juvana M; Ferreira, Rafael F; Santiago, André S; Pirovani, Carlos P; Silva-Pereira, Rosiane A; Murta, Silvane M F

    2013-08-01

    The emergence of drug-resistant Leishmania species is a significant problem in several countries. A comparative proteomic analysis of antimony-susceptible and antimony-resistant Leishmania braziliensis (LbSbR) and Leishmania infantum chagasi (LcSbR) lines was carried out using two-dimensional gel electrophoresis (2-DE) followed by mass spectrometry (LC/MS/MS) for protein identification. Out of 132 protein spots exclusive or up-regulated submitted to MS, we identified 80 proteins that corresponded to 57 distinct proteins. Comparative analysis of data showed that most of the protein spots with differential abundance in both species are involved in antioxidant defense, general stress response, glucose and amino acid metabolism, and cytoskeleton organization. Five proteins were commonly more abundant in both SbIII-resistant Leishmania lines: tryparedoxin peroxidase, alpha-tubulin, HSP70, HSP83, and HSP60. Analysis of the protein abundance by Western blotting assays confirmed our proteomic data. These assays revealed that cyclophilin-A is less expressed in both LbSbR and LcSbR lines. On the other hand, the expression of pteridine reductase is higher in the LbSbR line, whereas tryparedoxin peroxidase is overexpressed in both LbSbR and LcSbR lines. Together, these results show that the mechanism of antimony-resistance in Leishmania spp. is complex and multifactorial. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Growth, phenology, and seed viability between glyphosate-resistant and glyphosate-susceptible hary fleabane

    Directory of Open Access Journals (Sweden)

    Tiago Edu Kaspary

    Full Text Available ABSTRACT Glyphosate is the herbicide most used worldwide. In cropping systems that rely on repeated applications of glyphosate or cultivate genetically modified soyabean crop, there are numerous cases of glyphosate resistant weeds, including Conyza bonariensis. Differences among competitive ability of Conyza spp. have been found. However, little information is available on the fitness costs related to glyphosate resistance in Conyza bonariensis. We evaluated growth, phenology, and seed viability of glyphosate-resistant (GR and glyphosate-susceptible (GS Conyza bonariensis from Brazil, in 2012 (fall/winter and 2013 (spring/summer. When grown alone, in pots, C. bonariensis GR biotype developed more rapidly than the GS biotype, as evidenced by their earlier bolting, flowering, and seed set. In 2012, GR biotype showed 221.9 cm of plant height compared to 181.1 cm from GS, at the flowering time. In both years, the seed production per plant was superior for GR biotype, showing germination higher than 80% against 66.5% from the GS biotype. Thus, C. bonariensis GR biotype confirmed no fitness penalty also showing characteristics that allow us to infer in superior competitive with the absence of the herbicide. It is important to point out that the biotypes evaluated here have different genetic background and the differences between them may not be fully attributed to the resistance to glyphosate. However, the GR biotype can persist in the environment and outcompete with GS biotypes regardless of further glyphosate selection of pressure.

  16. [Occurrence and susceptibility to antibiotics of carbapenem-resistant Pseudomonas aeruginosa strains between 1998 and 2009].

    Science.gov (United States)

    Bogiel, Tomasz; Mikucka, Agnieszka; Skalski, Tomasz; Gospodarek, Eugenia

    2010-01-01

    P. aeruginosa rods are dangerous pathogens mainly responsible for nosocomial infections of different localization. Resistance to carbapenems, observed among them, is a serious threat due to ability to be transmitted between bacterial species. The aim of our study was to retrospectively evaluate the frequency of isolation and susceptibility to antibiotics of imipenem- and meropenem-resistant P. aeruginosa strains isolated between 1998 and 2009 from patients of University Hospital No 1 of dr A. Jurasz in Bydgoszcz. Study shows increasing number of isolation that type of strains from 19 in 1998 to 144 in 2009. Among all isolated P. aeruginosa strains majority was obtained from patients of the Intensive Care Units, Rehabilitation and Surgery Clinics. Examined strains of P. aeruginosa rods were mainly isolated from urine (20.5%), bronchoalveolar lavage (17.7%) and wound swabs (14.5%) samples. The isolates demonstrated frequently resistance to carbenicillin (> or 66.7%), ticarcillin (> or = 72.7%) and cefotaxime (> or = 75.6%). The lowest rate of resistant strains was observed in case of ceftazidime (< or = 68.8%), aztreonam (< or = 47.4%) and colistin (< or = 1.7%) suggesting the highest activity of that antimicrobials against infections caused by examined strains.

  17. Using Electrical Simulation Software to Understand Electrical Quantities in Resistive Circuits

    Directory of Open Access Journals (Sweden)

    André Schwantes

    2016-02-01

    Full Text Available This paper describes the development and application of a workshop presented for high school physics teachers, in order to apply the use of electrical simulation software for teaching the basics of resistive circuits. The workshop was developed aiming at the use of active learning strategies and the concepts of David Ausubel’s Meaningful Learning theory. These activities workshops were developed in a practical way, using the electrical simulation software to illustrate a scenario where students are encouraged to engage more actively in their learning. As a result of this workshop, an increase in the importance of the use of new technologies in the classroom was evidenced when used in accordance with the teaching-learning methodologies that promote a more active participation of students.

  18. Efficacy of an insecticide paint against insecticide-susceptible and resistant mosquitoes - Part 1: Laboratory evaluation

    Science.gov (United States)

    2010-01-01

    Background The main malaria vector Anopheles gambiae and the urban pest nuisance Culex quinquefasciatus are increasingly resistant to pyrethroids in many African countries. There is a need for new products and strategies. Insecticide paint Inesfly 5A IGR™, containing two organophosphates (OPs), chlorpyrifos and diazinon, and insect growth regulator (IGR), pyriproxyfen, was tested under laboratory conditions for 12 months following WHOPES Phase I procedures. Methods Mosquitoes used were laboratory strains of Cx. quinquefasciatus susceptible and resistant to OPs. The paint was applied at two different doses (1 kg/6 m2 and 1 kg/12 m2) on different commonly used surfaces: porous (cement and stucco) and non-porous (softwood and hard plastic). Insecticide efficacy was studied in terms of delayed mortality using 30-minute WHO bioassay cones. IGR efficacy on fecundity, fertility and larval development was studied on OP-resistant females exposed for 30 minutes to cement treated and control surfaces. Results After treatment, delayed mortality was high (87-100%) even against OP-resistant females on all surfaces except cement treated at 1 kg/12 m2. Remarkably, one year after treatment delayed mortality was 93-100% against OP-resistant females on non-porous surfaces at both doses. On cement, death rates were low 12 months after treatment regardless of the dose and the resistance status. Fecundity, fertility and adult emergence were reduced after treatment even at the lower dose (p paint's effect on fecundity, fertility and adult emergence may continue to provide an additional angle of attack in reducing overall population densities when the lethal effect of OPs diminishes over time. Some options on how to deal with porous materials are given. Implications in vector control are discussed. PMID:21108819

  19. Effect of antimicrobial peptides on colistin-susceptible and colistin-resistant strains of Klebsiella pneumoniae and Enterobacter asburiae.

    Science.gov (United States)

    Kádár, Béla; Kocsis, Béla; Kristof, Katalin; Tóth, Ákos; Szabó, Dóra

    2015-12-01

    In this study susceptibility to different antimicrobial peptides was investigated on colistin-susceptible and colistin-resistant identical pulsotype strains of KPC-2 producing Klebsiella pneumoniae ST258 as well as colistin-susceptible and colistin-resistant Enterobacter asburiae strains isolated from clinical samples. In our test, bacteria were exposed to 50 mg/ml lactoferrin, lysozyme and protamine - cationic antimicrobial peptides belonging to innate immune system and having structural similarity to polymyxins - in separate reactions. After 18 hours incubation of colonies were counted. 40% of colistin-resistant K. pneumoniae strains and 97% of colistin-susceptible counterpart strains were lysed by protamine whereas 87% and 100% colony forming unit decrease by lysozyme was seen, respectively. In the case of colistin-resistant E. asburiae strains 1 log10 cell count increase were observed after treatment with lysozyme and 1.56 log10 after lactoferrin exposure compared to the initial number whereas the colistin-susceptible showed no relevant cell count increase. Our findings suggest that acquired colistin-resistance in Enterobacteriaceae is associated with tolerance against antimicrobial peptides.

  20. Density-independent population projection trajectories of chromosome-substituted lines resistant and susceptible to organophosphate insecticides in Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Miyo Takahiro

    2004-11-01

    Full Text Available Abstract Background Seasonal fluctuations in susceptibility to organophosphate insecticides were observed in the Katsunuma population of Drosophila melanogaster for two consecutive years; susceptibility to three organophosphates tended to increase in the fall. To examine the hypothesis that variation in fitness among resistant and susceptible genotypes could trigger the change of genetic constitution within the fall population, we investigated density-independent population projection trajectories starting from single adult females with characteristics of chromosome-substituted lines resistant and susceptible to the three organophosphates. Results Density-independent population projection trajectories, expressed as the ratios of the number of each chromosome-substituted line to that of line SSS, for which all chromosomes were derived from the susceptible line, showed significant declines in numbers with time for all the resistant chromosome-substituted lines. Conclusion The declining tendency in the density-independent population projection trajectories of the resistant chromosome-substituted lines could explain the simultaneous decline in the levels of resistance to the three organophosphates, observed in the Katsunuma population in the fall.

  1. Characterization of reactive transport by 3‐D electrical resistivity tomography (ERT) under unsaturated conditions

    National Research Council Canada - National Science Library

    Wehrer, Markus; Binley, Andrew; Slater, Lee D

    2016-01-01

    .... In this study, we show how time lapse electrical resistivity tomography (ERT) can be used to characterize spatially heterogeneous processes of ion production, consumption, and transport in soils...

  2. UV-Cured Inkjet-Printed Silver Gate Electrode with Low Electrical Resistivity

    Science.gov (United States)

    Ning, Honglong; Zhou, Yicong; Fang, Zhiqiang; Yao, Rihui; Tao, Ruiqiang; Chen, Jianqiu; Cai, Wei; Zhu, Zhennan; Yang, Caigui; Wei, Jinglin; Wang, Lei; Peng, Junbiao

    2017-09-01

    Inkjet-printed silver gate electrode with low electrical resistivity was fabricated by UV curing method. By adjusting the UV curing time and the distance between the samples and UV lamp, the effects of UV curing conditions on the electrical resistivity of the silver films were studied, and the lowest electrical resistivity of 6.69 × 10-8 Ω·m was obtained. Besides, the UV-cured silver films have good adhesion to the glass substrates, with adhesion strength of 4B (ASTM international standard). Our work offered an easy and low temperature approach to fabricate inkjet-printed silver electrodes with low electrical resistivity.

  3. Mechanism of selective corrosion in electrical resistance seam welded carbon steel pipe

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Fajardo, Pedro; Godinez Salcedo, Jesus; Gonzalez Velasquez, Jorge L. [Instituto Politecnico Nacional, Mexico D.F., (Mexico). Escuela Superior de Ingenieria Quimica e Industrias Extractivas. Dept. de Ingenieria Metalurgica

    2009-07-01

    In this investigation the studies of the mechanism of selective corrosion in electrical resistance welded (ERW) carbon steel pipe was started. Metallographic characterizations and evaluations for inclusions were performed. The susceptibility of ERW pipe to selective corrosion in sea water (NACE 1D182, with O{sub 2} or CO{sub 2} + H{sub 2}S) was studied by the stepped potential Potentiostatic electrochemical test method in samples of 1 cm{sup 3} (ASTM G5) internal surface of the pipe (metal base-weld). The tests were looking for means for predicting the susceptibility of ERW pipe to selective corrosion, prior to placing the pipeline in service. Manganese sulfide inclusions are observed deformed by the welding process and they are close to the weld centerline. A slight decarburization at the weld line is observed, and a distinct out bent fiber pattern remains despite the post-weld seam annealing. The microstructure of the weld region consists of primarily polygonal ferrite grains mixed with small islands of pearlite. It is possible to observe the differences of sizes of grain of the present phases in the different zones. Finally, scanning electron microscopic observation revealed that the corrosion initiates with the dissolution of MnS inclusions and with small crack between the base metal and ZAC. (author)

  4. Multidrug resistant Acinetobacter baumannii: risk factors for appearance of imipenem resistant strains on patients formerly with susceptible strains.

    Directory of Open Access Journals (Sweden)

    Jung-Jr Ye

    Full Text Available BACKGROUND: Multidrug resistant Acinetobacter baumannii (MDRAB is an important nosocomial pathogen usually susceptible to carbapenems; however, growing number of imipenem resistant MDRAB (IR-MDRAB poses further clinical challenge. The study was designed to identify the risk factors for appearance of IR-MDRAB on patients formerly with imipenem susceptible MDRAB (IS-MDRAB and the impact on clinical outcomes. METHODOLOGY/PRINCIPAL FINDINGS: A retrospective case control study was carried out for 209 consecutive episodes of IS-MDRAB infection or colonization from August 2001 to March 2005. Forty-nine (23.4% episodes with succeeding clinical isolates of IR-MDRAB were defined as the cases and 160 (76.6% with all subsequent clinical isolates of IS-MDRAB were defined as the controls. Quantified antimicrobial selective pressure, "time at risk", severity of illness, comorbidity, and demographic data were incorporated for multivariate analysis, which revealed imipenem or meropenem as the only significant independent risk factor for the appearance of IR-MDRAB (adjusted OR, 1.18; 95% CI, 1.09 to 1.27. With selected cases and controls matched to exclude exogenous source of IR-MDRAB, multivariate analysis still identified carbapenem as the only independent risk factor (adjusted OR, 1.48; 95% CI, 1.14 to 1.92. Case patients had a higher crude mortality rate compared to control patients (57.1% vs. 31.3%, p = 0.001, and the mortality of case patients was associated with shorter duration of "time at risk", i.e., faster appearance of IR-MDRAB (adjusted OR, 0.9; 95% CI, 0.83 to 0.98. CONCLUSIONS/SIGNIFICANCE: Judicious use of carbapenem with deployment of antibiotics stewardship measures is critical for reducing IR-MDRAB and the associated unfavorable outcome.

  5. ANALYSIS OF EXCESSIVE HEATING ON THE THERMAL AND ELECTRICAL RESISTANCE OF A POLYMER ELECTROLYTE

    National Research Council Canada - National Science Library

    R. Atan; W. A. N. W. Mohamed

    2012-01-01

    .... An analytical method by which the electrical resistance is evaluated based on the polarisation curve and the thermal resistance from the mass balance, was applied to a 72-cell PEM fuel cell assembly...

  6. Morphological Characteristics of Schistosoma mansoni PZQ-resistant and -susceptible Strains are Different in Presence of Praziquantel

    Directory of Open Access Journals (Sweden)

    António ePinto-Almeida

    2016-04-01

    Full Text Available Schistosomiasis is one of the most common human parasitic diseases whose socioeconomic impact is only surpassed by malaria. Praziquantel (PZQ is the only drug commercially available for the treatment of all schistosome species causing disease in humans. However, there has been stronger evidences of PZQ-resistance on Schistosoma mansoni and thus it is very important to study the phenotypic characteristics associated with it. The aim of this study was to evaluate morphological alterations in S. mansoni PZQ-resistant adult worms and eggs, by comparing a PZQ-resistant strain obtained under PZQ drug pressure with a PZQ-susceptible strain. For this, scanning electronic microscopy was used to assess tegumental responsiveness of both strains under PZQ exposure, and optical microscopy allowed the monitoring of worms and eggs in the presence of the drug. Those assays showed that PZQ-susceptible worms exposed to the drug had more severe tegumental damages than the resistant one, which had only minor alterations. Moreover, contrary to what occurred in the susceptible strain, resistant worms were viable after PZQ exposure and gradually regaining full motility after removal of the drug. Eggs from resistant strain parasites are considerably smaller than those from susceptible strain. Our results suggest that there might be a difference in the tegument composition of the resistant strain and that worms are less responsive to PZQ. Changes observed in egg morphology might imply alterations in the biology of schistosomes associated to PZQ-resistance, which could impact on transmission and pathology of the disease. Moreover, we propose a hypothetical scenario where there is a different egg tropism of the S. mansoni resistant strain. This study is the first comparing two strains that only differ in their resistance characteristics, which makes it a relevant step in the search for resistance determinants.

  7. Antibiotic susceptibility/resistant gene profiles of Group B streptococci isolates from pregnant women in a tertiary institution in Nigeria

    Directory of Open Access Journals (Sweden)

    Charles J Elikwu

    2016-01-01

    Full Text Available Background: Penicillin is recommended as the first-line agent for intrapartum antibiotic prophylaxis (IAP. Although Group B Streptococcus (GBS strains are generally susceptible to penicillin with only occasional resistance, they show varying resistance to erythromycin, clindamycin, and tetracycline. Therefore, knowledge of the resistance profile of GBS in the local environment will be useful for administration of appropriate intrapartum antibiotics prophylaxis. Methodology: Rectovaginal swabs collected from pregnant women were cultured for GBS using conventional media. Kirby-Bauer disc diffusion method was performed according to the Clinical and Laboratory Standards Institute guidelines on GBS isolates to determine the antibiotic susceptibility patterns of the isolates. Inducible clindamycin resistance was detected by using the D-zone test. Resistance determinants genes were discerned with conventional polymerase chain reaction. Results: Carriage rates of GBS among pregnant women studied were 19.7%. GBS colonizing the pregnant mothers were uniformly susceptible (100% to penicillin, vancomycin, and ceftriaxone. Only three (6.5% of the isolates showed inducible clindamycin resistance. ermA gene was present in all three GBS isolates with inducible macrolide-lincosamide-streptogramin resistance. ermB was absent in all the strains tested. mefA/E gene was carried by two of the macrolide-clindamycin resistance isolates. tetM gene was carried by all isolates with tetracycline resistance phenotypes. Conclusion: In this study, all GBS isolates were susceptible to penicillin G, the recommended antibiotic for IAP. The presence of resistance to erythromycin and inducible resistance to clindamycin excludes the use of these agents as alternatives in cases of penicillin allergy. In this case, vancomycin is the drug of choice as recommended in the updated Centers for Disease Control guideline.

  8. Identification of maize genes associated with host plant resistance or susceptibility to Aspergillus flavus infection and aflatoxin accumulation.

    Directory of Open Access Journals (Sweden)

    Rowena Y Kelley

    Full Text Available BACKGROUND: Aspergillus flavus infection and aflatoxin contamination of maize pose negative impacts in agriculture and health. Commercial maize hybrids are generally susceptible to this fungus. Significant levels of host plant resistance have been observed in certain maize inbred lines. This study was conducted to identify maize genes associated with host plant resistance or susceptibility to A. flavus infection and aflatoxin accumulation. RESULTS: Genome wide gene expression levels with or without A. flavus inoculation were compared in two resistant maize inbred lines (Mp313E and Mp04:86 in contrast to two susceptible maize inbred lines (Va35 and B73 by microarray analysis. Principal component analysis (PCA was used to find genes contributing to the larger variances associated with the resistant or susceptible maize inbred lines. The significance levels of gene expression were determined by using SAS and LIMMA programs. Fifty candidate genes were selected and further investigated by quantitative RT-PCR (qRT-PCR in a time-course study on Mp313E and Va35. Sixteen of the candidate genes were found to be highly expressed in Mp313E and fifteen in Va35. Out of the 31 highly expressed genes, eight were mapped to seven previously identified quantitative trait locus (QTL regions. A gene encoding glycine-rich RNA binding protein 2 was found to be associated with the host hypersensitivity and susceptibility in Va35. A nuclear pore complex protein YUP85-like gene was found to be involved in the host resistance in Mp313E. CONCLUSION: Maize genes associated with host plant resistance or susceptibility were identified by a combination of microarray analysis, qRT-PCR analysis, and QTL mapping methods. Our findings suggest that multiple mechanisms are involved in maize host plant defense systems in response to Aspergillus flavus infection and aflatoxin accumulation. These findings will be important in identification of DNA markers for breeding maize lines

  9. A Prototype System for Time-Lapse Electrical Resistivity Tomographies

    Directory of Open Access Journals (Sweden)

    Raffaele Luongo

    2012-01-01

    Full Text Available A prototype system for time-lapse acquisition of 2D electrical resistivity tomography (ERT and time domain reflectometry (TDR measurements was installed in a test site affected by a landslide in Basilicata region (southern Italy. The aim of the system is to monitor in real-time the rainwater infiltration into the soil and obtain information about the variation of the water content in the first layers of the subsoil and the possible influence of this variation on landslide activity. A rain gauge placed in the test site gives information on the rainfall intensity and frequency and suggests the acquisition time interval. The installed system and the preliminary results are presented in this paper.

  10. In vitro activities of a new lipopeptide, HMR 1043, against susceptible and resistant gram-positive isolates.

    Science.gov (United States)

    Bemer, Pascale; Juvin, Marie-Emmanuelle; Bryskier, Andre; Drugeon, Henri

    2003-09-01

    The purpose of this study was to compare the activity of HMR 1043 with those of daptomycin and teicoplanin against gram-positive isolates. Susceptibility tests were performed for 52 strains, 26 parental strains, including staphylococcal, streptococcal, enterococcal, and listerial strains, and 26 HMR 1043-resistant mutants obtained from parental strains by using the Szybalski method. Agar dilution and disk diffusion susceptibility tests were performed by the procedures outlined by the NCCLS. HMR 1043 demonstrated good activity against susceptible and resistant gram-positive bacteria. The activity of HMR 1043 in vitro was less influenced by the presence of calcium ions than that of daptomycin. Susceptibility test breakpoints were not defined because of the poor correlation coefficients obtained with the different disks tested.

  11. The development of a mouse model to explore resistance and susceptibility to early Ascaris suum infection.

    Science.gov (United States)

    Lewis, R; Behnke, J M; Stafford, P; Holland, C V

    2006-02-01

    Ascaris suum and Ascaris lumbricoides exhibit an over-dispersed frequency distribution in their host populations in both the adult and larval stages. The impact of host factors on this observed distribution is still poorly understood and difficult to investigate in the natural host populations. The use of a mouse model has been supported by the observations that the larval migratory pattern, in this host, mimics the pattern observed in the pig. We explored the extrinsic factors that might affect the quantitative recovery of larvae during this migration in order to standardize a model system facilitating accurate future assessment of host genetic variation on this phase of the infection. In Exp. 1 larvae accumulated in the livers of both C57BL/6j and BALB/c mice up to and including days 4-5 p.i. and then declined in both strains until day 9. Loss of larvae from the livers corresponded to arrival in the lungs and maximum accumulation on day 7 p.i. but recovery was considerably higher in C57BL/6j mice. It was concluded that day 7 recoveries gave the best indication of relative resistance/susceptibility to this parasite. In Exp. 2 A/J, BALB/c, CBA/Ca, C57BL/6j, C3H/HeN, DBA/2, NIH, SJL, and SWR mice were compared. C57BL/6j mice were identified as the most susceptible strain and CBA/Ca mice as having the most contrasting phenotype, but with a similar kinetic pattern of migration. Finally, in Exp. 3, a strong positive correlation between the size of the inoculum and the mean worm recovery from the lungs was found in CBA/Ca and C57BL/6j mice, but the difference between these strains was highly consistent, 66.6-80%, regardless of the initial dose. These results demonstrate that, using our protocols for infection and recovery, between-experiment variation in A. suum worm burdens is minimal, and that C57BL/6j mice are highly susceptible to infection compared to other strains. The mechanistic basis of this susceptibility in relation to the resistance of other strains is

  12. Soil Moisture Monitoring using Surface Electrical Resistivity measurements

    Science.gov (United States)

    Calamita, Giuseppe; Perrone, Angela; Brocca, Luca; Straface, Salvatore

    2017-04-01

    The relevant role played by the soil moisture (SM) for global and local natural processes results in an explicit interest for its spatial and temporal estimation in the vadose zone coming from different scientific areas - i.e. eco-hydrology, hydrogeology, atmospheric research, soil and plant sciences, etc... A deeper understanding of natural processes requires the collection of data on a higher number of points at increasingly higher spatial scales in order to validate hydrological numerical simulations. In order to take the best advantage of the Electrical Resistivity (ER) data with their non-invasive and cost-effective properties, sequential Gaussian geostatistical simulations (sGs) can be applied to monitor the SM distribution into the soil by means of a few SM measurements and a densely regular ER grid of monitoring. With this aim, co-located SM measurements using mobile TDR probes (MiniTrase), and ER measurements, obtained by using a four-electrode device coupled with a geo-resistivimeter (Syscal Junior), were collected during two surveys carried out on a 200 × 60 m2 area. Two time surveys were carried out during which Data were collected at a depth of around 20 cm for more than 800 points adopting a regular grid sampling scheme with steps (5 m) varying according to logistic and soil compaction constrains. The results of this study are robust due to the high number of measurements available for either variables which strengthen the confidence in the covariance function estimated. Moreover, the findings obtained using sGs show that it is possible to estimate soil moisture variations in the pedological zone by means of time-lapse electrical resistivity and a few SM measurements.

  13. Infiltration front monitoring using 3D Electrical Resistivity Tomography

    Science.gov (United States)

    Oxarango, Laurent; Audebert, Marine; Guyard, Helene; Clement, Remi

    2016-04-01

    The electrical resistivity tomography (ERT) geophysical method is commonly used to identify the spatial distribution of electrical resisitivity in the soil at the field scale. Recent progress in commercial acquisition systems allows repeating fast acquisitions (10 min) in order to monitor a 3D dynamic phenomenon. Since the ERT method is sensitive to moisture content variations, it can thus be used to delineate the infiltration shape during water infiltration. In heterogeneous conditions, the 3D infiltration shape is a crucial information because it could differ significantly from the homogeneous behavior. In a first step, the ERT method is validated at small scale (resistivity probes and 3 commercial capacitive moisture content probes to provide local measurements of the moisture content variation. The Multiple Inversion and Clustering Strategy (MICS) (Audebert et al 2014) is used to delineate the infiltration patern. A satisfying agreement between infiltration delineation and sensor measurements is obtained with a few centimeter accuracy on the moisture front location. In a second step, the same methodology is applied at a larger scale (> 10m). Two examples of leachate injection monitoring in municipal solid waste landfills are used to put forward benefits and limitations of the ERT-MICS method. Effective infiltration porosities in a range between 3% and 8% support the assumption of a flow in heterogeneous media. Audebert, M., R. Clément, N. Touze-Foltz, T. Günther, S. Moreau, and C. Duquennoi (2014), Time-lapse ERT interpretation methodology for leachate injection monitoring based on multiple inversions and a clustering strategy (MICS), Journal of Applied Geophysics, 111, 320-333. Keywords: ERT, infiltration front, field survey

  14. An alternative methodology for the analysis of electrical resistivity data from a soil gas study

    OpenAIRE

    Johansson, Sara; Rosqvist, Hakan; Svensson, Mats; Dahlin, Torleif; Leroux, Virginie

    2011-01-01

    The aim of this paper is to present an alternative method for the analysis of resistivity data. The methodology was developed during a study to evaluate if electrical resistivity can be used as a tool for analysing subsurface gas dynamics and gas emissions from landfills. The main assumption of this study was that variations in time of resistivity data correspond to variations in the relative amount of gas and water in the soil pores. Field measurements of electrical resistivity, static chamb...

  15. Annotated differentially expressed salivary proteins of susceptible and insecticide-resistant mosquitoes of Anopheles stephensi.

    Directory of Open Access Journals (Sweden)

    Sonam Vijay

    Full Text Available Vector control is one of the major global strategies for control of malaria. However, the major obstacle for vector control is the development of multiple resistances to organochlorine, organophosphorus insecticides and pyrethroids that are currently being used in public health for spraying and in bednets. Salivary glands of vectors are the first target organ for human-vector contact during biting and parasite-vector contact prior to parasite development in the mosquito midguts. The salivary glands secrete anti-haemostatic, anti-inflammatory biologically active molecules to facilitate blood feeding from the host and also inadvertently inject malaria parasites into the vertebrate host. The Anopheles stephensi mosquito, an urban vector of malaria to both human and rodent species has been identified as a reference laboratory model to study mosquito-parasite interactions. In this study, we adopted a conventional proteomic approach of 2D-electrophoresis coupled with MALDI-TOF mass spectrometry and bioinformatics to identify putative differentially expressed annotated functional salivary proteins between An. stephensi susceptible and multiresistant strains with same genetic background. Our results show 2D gel profile and MALDI-TOF comparisons that identified 31 differentially expressed putative modulated proteins in deltamethrin/DDT resistant strains of An. stephensi. Among these 15 proteins were found to be upregulated and 16 proteins were downregulated. Our studies interpret that An. stephensi (multiresistant caused an upregulated expression of proteins and enzymes like cytochrome 450, short chain dehyrdogenase reductase, phosphodiesterase etc that may have an impact in insecticide resistance and xenobiotic detoxification. Our study elucidates a proteomic response of salivary glands differentially regulated proteins in response to insecticide resistance development which include structural, redox and regulatory enzymes of several pathways. These

  16. Annotated differentially expressed salivary proteins of susceptible and insecticide-resistant mosquitoes of Anopheles stephensi.

    Science.gov (United States)

    Vijay, Sonam; Rawal, Ritu; Kadian, Kavita; Raghavendra, Kamaraju; Sharma, Arun

    2015-01-01

    Vector control is one of the major global strategies for control of malaria. However, the major obstacle for vector control is the development of multiple resistances to organochlorine, organophosphorus insecticides and pyrethroids that are currently being used in public health for spraying and in bednets. Salivary glands of vectors are the first target organ for human-vector contact during biting and parasite-vector contact prior to parasite development in the mosquito midguts. The salivary glands secrete anti-haemostatic, anti-inflammatory biologically active molecules to facilitate blood feeding from the host and also inadvertently inject malaria parasites into the vertebrate host. The Anopheles stephensi mosquito, an urban vector of malaria to both human and rodent species has been identified as a reference laboratory model to study mosquito-parasite interactions. In this study, we adopted a conventional proteomic approach of 2D-electrophoresis coupled with MALDI-TOF mass spectrometry and bioinformatics to identify putative differentially expressed annotated functional salivary proteins between An. stephensi susceptible and multiresistant strains with same genetic background. Our results show 2D gel profile and MALDI-TOF comparisons that identified 31 differentially expressed putative modulated proteins in deltamethrin/DDT resistant strains of An. stephensi. Among these 15 proteins were found to be upregulated and 16 proteins were downregulated. Our studies interpret that An. stephensi (multiresistant) caused an upregulated expression of proteins and enzymes like cytochrome 450, short chain dehyrdogenase reductase, phosphodiesterase etc that may have an impact in insecticide resistance and xenobiotic detoxification. Our study elucidates a proteomic response of salivary glands differentially regulated proteins in response to insecticide resistance development which include structural, redox and regulatory enzymes of several pathways. These identified proteins

  17. Local nematic susceptibility in stressed BaFe2As2 from NMR electric field gradient measurements

    Science.gov (United States)

    Kissikov, T.; Sarkar, R.; Lawson, M.; Bush, B. T.; Timmons, E. I.; Tanatar, M. A.; Prozorov, R.; Bud'ko, S. L.; Canfield, P. C.; Fernandes, R. M.; Goh, W. F.; Pickett, W. E.; Curro, N. J.

    2017-12-01

    The electric field gradient (EFG) tensor at the 75As site couples to the orbital occupations of the As p orbitals and is a sensitive probe of local nematicity in BaFe2As2 . We use nuclear magnetic resonance to measure the nuclear quadrupolar splittings and find that the EFG asymmetry responds linearly to the presence of a strain field in the paramagnetic phase. We extract the nematic susceptibility from the slope of this linear response as a function of temperature and find that it diverges near the structural transition, in agreement with other measures of the bulk nematic susceptibility. Our work establishes an alternative method to extract the nematic susceptibility which, in contrast to transport methods, can be extended inside the superconducting state.

  18. Rapid antimicrobial susceptibility test for identification of new therapeutics and drug combinations against multidrug-resistant bacteria

    OpenAIRE

    Sun, Wei; Weingarten, Rebecca A; Xu, Miao; Southall, Noel; Dai, Sheng; Shinn, Paul; Sanderson, Philip E; Williamson, Peter R; Frank, Karen M; Zheng, Wei

    2016-01-01

    Current antimicrobial susceptibility testing has limited screening capability for identifying empirical antibiotic combinations to treat severe bacterial infections with multidrug-resistant (MDR) organisms. We developed a new antimicrobial susceptibility assay using automated ultra-high-throughput screen technology in combination with a simple bacterial growth assay. A rapid screening of 5170 approved drugs and other compounds identified 25 compounds with activities against MDR Klebsiella pne...

  19. Applications of electrical resistance tomography to subsurface environmental restoration

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, A.L. [Lawrence Livermore National Lab., CA (United States); Daily, W.D.

    1994-11-15

    We are developing a new imaging technique, Electrical Resistance Tomography (ERT), to map subsurface liquids as flow occurs during natural or clean-up processes and to map geologic structure. Natural processes (such as surface water infiltrating the vadose zone) and man-induced processes (such as tank leaks and clean-up processes such as steam injection), can create changes in a soil`s electrical properties that are readily measured. We have conducted laboratory and a variety of field experiments to investigate the capabilities and limitations of ERT for imaging underground structures and processes. In the last four years we have used ERT to successfully monitor several field processes including: a subsurface steam injection process (for VOC removal), an air injection process (below the water table) for VOC removal, water infiltration through the vadose zone, radio-frequency heating, ohmic heating, and tank and pond leaks. The information derived from ERT can be used by remediation projects to: detect and locate leaks, determine the effectiveness of clean-up processes, select appropriate clean-up alternatives, and to verify the installation and performance of subsurface barriers.

  20. Mapping of quantitative trait loci affecting resistance/susceptibility to Sarcocystis miescheriana in swine.

    Science.gov (United States)

    Reiner, Gerald; Kliemt, Damaris; Willems, Hermann; Berge, Thomas; Fischer, Reiner; Köhler, Florian; Hepp, Sabine; Hertrampf, Barbara; Daugschies, Arwid; Geldermann, Hermann; Mackenstedt, Ute; Zahner, Horst

    2007-05-01

    The outcome of infectious diseases in vertebrates is under genetic control at least to some extent. In swine, e.g., marked differences in resistance/susceptibility to Sarcocystis miescheriana have been shown between Chinese Meishan and European Pietrain pigs, and these differences are associated with high heritabilities. A first step toward the identification of genes and polymorphisms causal for these differences may be the mapping of quantitative trait loci (QTLs). Considering clinical, immunological, and parasitological traits in the above model system, this survey represents the first QTL study on parasite resistance in pigs. QTL mapping was performed in 139 F(2) pigs of a Meishan/Pietrain family infected with S. miescheriana. Fourteen genome-wide significant QTLs were mapped to several chromosomal areas. Among others, major QTLs were identified for bradyzoite numbers in skeletal muscles (F = 17.4; p < 0.001) and for S. miescheriana-specific plasma IgG(2) levels determined 42 days p.i. (F = 20.9; p < 0.001). The QTLs were mapped to different regions of chromosome 7, i.e., to the region of the major histocompatibility complex (bradyzoites) and to an immunoglobulin heavy chain cluster, respectively. These results provide evidence for a direct and causal role for gene variants within these gene clusters (cis-acting) in differences in resistance to S. miescheriana.

  1. Complementary assays for monitoring susceptibility of varicella-zoster virus resistance to antivirals.

    Science.gov (United States)

    Perrier, Marine; Désiré, Nathalie; Deback, Claire; Agut, Henri; Boutolleau, David; Burrel, Sonia

    2016-07-01

    The emergence of varicella-zoster virus (VZV) resistance to current antivirals as acyclovir (ACV) constitutes a hindrance to antiviral treatment effectiveness of VZV infections, especially in immunocompromised patients. The molecular mechanisms of VZV resistance reported so far rely on the presence of mutations within thymidine kinase (TK, ORF36) and DNA polymerase (ORF28) viral genes. The aim of this work was to develop reliable and complementary diagnostic methods to detect VZV antiviral resistance: (i) a genotypic assay based on TK and DNA polymerase genes sequencing, (ii) a plaque reduction assay to determine antiviral 50% effective concentrations, and (iii) a functional assay to evaluate in vitro phosphorylation activity of recombinant TKs. As a whole, this study included the analysis of 21 VZV clinical isolates and 62 biological samples from patients experiencing VZV infection. Genetic analysis revealed 3 and 9 new amino acid changes that have not been previously described within the highly conserved TK and DNA polymerase, respectively. Then, VZV isolates bearing newly identified mutations considered as natural polymorphisms were characterized as susceptible to ACV using plaque-reduction assay in MeWo cells. In parallel, the impact of TK changes on ACV phosphorylation activity was examined using a nonradioactive in vitro enzymatic assay. Copyright © 2016. Published by Elsevier B.V.

  2. Fitness and competitive growth comparison of methicillin resistant and methicillin susceptible Staphylococcus aureus colonies.

    Science.gov (United States)

    Durhan, Emine; Korcan, Safiye Elif; Altindis, Mustafa; Konuk, Muhsin

    2017-05-01

    Exponential developments of both Methicillin resistant Staphylococcus aureus (MRSA) 3R ve 36R and methicillin susceptible Staphylococcus aureus (MSSA) 27S were evaluated in the presence and absence of oxacillin. The strains were isolated from the specimens collected in microbiology department. It was also determined the transfer of mecA gene from 3R to 27S strain by using the replica plate technique. It was observed that the presence of antibiotics in the preliminary culture had a positive impact on the growth of the secondary culture of MRSA isolates. Comparison results of Rt bacteria in three different mixed cultures, assessed with Tukey's HSD test, showed a significant statistical difference among the groups. The values were as following; on the first day; Df: 2, F: 60.90, P: 0.0001, second day; Df:2, F:90.56, P: 0.0000, and third day; Df:2, F:4.86, P:0.0557. As a result of the study, we can suggest that the gene expression levels of the transferred antibiotic resistance genes could help us in both controlling hospital originated sickness and developing new strategies to prevent the spread of resistant bacteria. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Contribution of 3-D electrical resistivity tomography for landmines detection

    Directory of Open Access Journals (Sweden)

    M. Metwaly

    2008-12-01

    Full Text Available Landmines are a type of inexpensive weapons widely used in the pre-conflicted areas in many countries worldwide. The two main types are the metallic and non-metallic (mostly plastic landmines. They are most commonly investigated by magnetic, ground penetrating radar (GPR, and metal detector (MD techniques. These geophysical techniques however have significant limitations in resolving the non-metallic landmines and wherever the host materials are conductive. In this work, the 3-D electric resistivity tomography (ERT technique is evaluated as an alternative and/or confirmation detection system for both landmine types, which are buried in different soil conditions and at different depths. This can be achieved using the capacitive resistivity imaging system, which does not need direct contact with the ground surface. Synthetic models for each case have been introduced using metallic and non-metallic bodies buried in wet and dry environments. The inversion results using the L1 norm least-squares optimization method tend to produce robust blocky models of the landmine body. The dipole axial and the dipole equatorial arrays tend to have the most favorable geometry by applying dynamic capacitive electrode and they show significant signal strength for data sets with up to 5% noise. Increasing the burial depth relative to the electrode spacing as well as the noise percentage in the resistivity data is crucial in resolving the landmines at different environments. The landmine with dimension and burial depth of one electrode separation unit is over estimated while the spatial resolutions decrease as the burial depth and noise percentage increase.

  4. [Antimicrobial susceptibility and molecular characterization of multidrug-resistant Acinetobacter baumannii isolated in an university hospital].

    Science.gov (United States)

    Direkel, Şahin; Çopur Çiçek, Ayşegül; Karagöz, Alper; Aydoğan Ejder, Nebahat; Oktay, Efdal; Delialioğlu, Nuran; Özgümüş, Osman Birol; Durmaz, Rıza

    2016-10-01

    Acinetobacter baumannii, an aerobic, non-motile, gram-negative bacterium is an important nosocomial pathogen which shows resistance to the most antibiotics. Carbapenems are the most commonly used antibiotics for the treatment of infections caused by this pathogen. However the emergence of resistance against carbapenems in an increasing rate generates serious problems for antimicrobial therapy. The aims of this study were to detect the antibiotic susceptibility, and the presence of blaOXA resistance genes of clinical A.baumannii isolates and to determine the clonal relationship between these isolates. A total of 79 A.baumannii strains isolated from various clinical specimens (37 respiratory tract samples, 11 wound, 10 blood, 8 catheters, 6 tissue, 5 urine, 2 abscess) of the patients admitted to Mersin University Medical School Hospital between May 2012-January 2013, were included in the study. The isolates were identified by conventional methods and Vitek®2 Compact automated system. Antibiotic susceptibilities of the isolates were determined by Kirby-Bauer disk diffusion method and evaluated according to CLSI criteria. The presence of blaOXA-51, blaOXA-23, blaOXA-24, blaOXA-48 and blaOXA-58 genes were detected by an in-house polymerase chain reaction (PCR), and the clonal relationship between the isolates were identified by pulsed-field gel electroforesis (PFGE) using the ApaI restriction enzyme. In our study, all of the isolates were susceptible to colistin, while the resistance rates against piperacillin-tazobactam, ciprofloxacin, imipenem, meropenem, cefoperazone/sulbactam, trimethoprim-sulfamethoxazole, ceftazidime, levofloxacin, gentamicin, tetracycline, ampicillin-sulbactam, amikacin, netilmicin and tigecycline were 97.5%, 96.2%, 94.9%, 94.9%, 93.6%, 91.1%, 88.6%, 86%, 83.6%, 77.2%, 69.6%, 55.7%, 27.8% and 3.8%, respectively. All the isolates were identified as A.baumannii with the OXA-specific PCR and OXA16S rDNA sequence analysis. All of the isolates (100

  5. Community-acquired methicillin-resistant Staphylococcus aureus carriage rate and antimicrobial susceptibility in a tertiary center, Iran.

    Science.gov (United States)

    Shokouhi, Shervin; Darazam, Ilad Alavi; Zamanian, Mohammad-Hossein

    2017-01-01

    This study was aimed to determine frequency and antimicrobial susceptibility of Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) among colonized patients in outpatient status. A total of 2000 nasal nares specimens were collected and inoculated on mannitol salt agar. MRSAs were identified based on mannitol positivity and coagulase test followed by cefoxitin disc diffusion test. Antimicrobial susceptibility of MRSA isolates was performed by E-test method for vancomycin and doxycycline as well as disc diffusion method for sulfamethoxazole-trimethoprim (SMX-TMP), erythromycin, linezolid, and clindamycin. D-test was performed for detection of inducible resistance to clindamycin. Overall, nasal carrier rate of S. aureus and CA-MRSA was estimated 22% and 1.25%, respectively. Out of the 440 S. aureus isolates, 25 isolates were MRSA. All were susceptible to vancomycin and linezolid, and susceptibility rates to SMX-TMP, erythromycin, levofloxacin, doxycycline, and clindamycin were 68%, 44%, 48%, 40% and 44%, respectively; furthermore, 28.5% of resistant isolates to erythromycin had inducible resistance to clindamycin. It seems susceptibility to clindamycin and SMX-TMP, recommended agents for empirical treatment of suspected CA-MRSA, are not promising. Vancomycin and linezolid are effective and reliable antibiotics for the treatment of S. aureus infections.

  6. Community-acquired methicillin-resistant Staphylococcus aureus carriage rate and antimicrobial susceptibility in a tertiary center, Iran

    Directory of Open Access Journals (Sweden)

    Shervin Shokouhi

    2017-01-01

    Full Text Available Background: This study was aimed to determine frequency and antimicrobial susceptibility of Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA among colonized patients in outpatient status. Materials and Methods: A total of 2000 nasal nares specimens were collected and inoculated on mannitol salt agar. MRSAs were identified based on mannitol positivity and coagulase test followed by cefoxitin disc diffusion test. Antimicrobial susceptibility of MRSA isolates was performed by E-test method for vancomycin and doxycycline as well as disc diffusion method for sulfamethoxazole-trimethoprim (SMX-TMP, erythromycin, linezolid, and clindamycin. D-test was performed for detection of inducible resistance to clindamycin. Results: Overall, nasal carrier rate of S. aureus and CA-MRSA was estimated 22% and 1.25%, respectively. Out of the 440 S. aureus isolates, 25 isolates were MRSA. All were susceptible to vancomycin and linezolid, and susceptibility rates to SMX-TMP, erythromycin, levofloxacin, doxycycline, and clindamycin were 68%, 44%, 48%, 40% and 44%, respectively; furthermore, 28.5% of resistant isolates to erythromycin had inducible resistance to clindamycin. Conclusion: It seems susceptibility to clindamycin and SMX-TMP, recommended agents for empirical treatment of suspected CA-MRSA, are not promising. Vancomycin and linezolid are effective and reliable antibiotics for the treatment of S. aureus infections.

  7. Fnip1 regulates skeletal muscle fiber type specification, fatigue resistance, and susceptibility to muscular dystrophy.

    Science.gov (United States)

    Reyes, Nicholas L; Banks, Glen B; Tsang, Mark; Margineantu, Daciana; Gu, Haiwei; Djukovic, Danijel; Chan, Jacky; Torres, Michelle; Liggitt, H Denny; Hirenallur-S, Dinesh K; Hockenbery, David M; Raftery, Daniel; Iritani, Brian M

    2015-01-13

    Mammalian skeletal muscle is broadly characterized by the presence of two distinct categories of muscle fibers called type I "red" slow twitch and type II "white" fast twitch, which display marked differences in contraction strength, metabolic strategies, and susceptibility to fatigue. The relative representation of each fiber type can have major influences on susceptibility to obesity, diabetes, and muscular dystrophies. However, the molecular factors controlling fiber type specification remain incompletely defined. In this study, we describe the control of fiber type specification and susceptibility to metabolic disease by folliculin interacting protein-1 (Fnip1). Using Fnip1 null mice, we found that loss of Fnip1 increased the representation of type I fibers characterized by increased myoglobin, slow twitch markers [myosin heavy chain 7 (MyH7), succinate dehydrogenase, troponin I 1, troponin C1, troponin T1], capillary density, and mitochondria number. Cultured Fnip1-null muscle fibers had higher oxidative capacity, and isolated Fnip1-null skeletal muscles were more resistant to postcontraction fatigue relative to WT skeletal muscles. Biochemical analyses revealed increased activation of the metabolic sensor AMP kinase (AMPK), and increased expression of the AMPK-target and transcriptional coactivator PGC1α in Fnip1 null skeletal muscle. Genetic disruption of PGC1α rescued normal levels of type I fiber markers MyH7 and myoglobin in Fnip1-null mice. Remarkably, loss of Fnip1 profoundly mitigated muscle damage in a murine model of Duchenne muscular dystrophy. These results indicate that Fnip1 controls skeletal muscle fiber type specification and warrant further study to determine whether inhibition of Fnip1 has therapeutic potential in muscular dystrophy diseases.

  8. Towards a Global Permafrost Electrical Resistivity Survey (GPERS) database

    Science.gov (United States)

    Lewkowicz, Antoni G.; Douglas, Thomas; Hauck, Christian

    2017-04-01

    Hundreds, and perhaps thousands, of Electrical Resistivity Tomography (ERT) surveys have been undertaken over the past two decades in permafrost areas in North America, Europe, and Asia. Two main types of ERT configurations have been conducted: galvanic surveys using metallic rods as conductors and capacitive-coupled surveys using towed cable arrays. ERT surveys have been carried out in regions with mountain permafrost, lowland permafrost, and coastal saline permafrost, and in undisturbed, naturally-disturbed (e.g. fire-affected), and anthropogenically-affected sites (e.g. around buildings and infrastructure). Some surveys are associated with local validation of frozen ground conditions, through borehole temperatures, frost probing or creep phenomena. Others are in locations without boreholes or with clast-rich or bedrock active layers which preclude this direct confirmation. Most surveys have been carried out individually on particular dates but there are increasing numbers of repeated ERT measurements being made to detect change, either at intervals using a fixed array of electrodes, or at high frequency with a fixed and automated measurement apparatus. Taken as a group, ERT profiles represent an untapped knowledge base relating to permafrost presence, absence, or partial presence (i.e. discontinuous permafrost), and in some cases to the thickness of permafrost and ice content. When combined with borehole information, ERT measurements can identify massive ice features and provides information on soil stratigraphy. The Global Permafrost Electrical Resistivity Survey (GPERS) database is planned as a freely available on-line repository of data from two-dimensional electrical resistivity surveys undertaken in permafrost regions. Its development is supported by the Permafrost Carbon Network and an application for an International Permafrost Association (IPA) Action Group is also underway. When the future GPERS records are compared with the GTN-P database it will be

  9. Susceptibility to chlorhexidine amongst multidrug-resistant clinical isolates of Staphylococcus epidermidis from bloodstream infections.

    Science.gov (United States)

    Hijazi, Karolin; Mukhopadhya, Indrani; Abbott, Felicity; Milne, Kathleen; Al-Jabri, Zaaima J; Oggioni, Marco R; Gould, Ian M

    2016-07-01

    The emergence of Staphylococcus isolates with reduced susceptibility to chlorhexidine is being increasingly reported. We present an update to a previous report showing the continuing efficacy of chlorhexidine-based infection control measures against Staphylococcus aureus over 6 years. In this study, qacA/B genes were screened in Staphylococcus isolates collected over another 6 years in the same intensive care unit in Scotland where chlorhexidine baths form an essential component of long-term control of nosocomial infections. Consistent with our previous study, we report minimal presence of qacA/B in S. aureus strains from screening samples and bacteraemia patients but the new finding of a high proportion of qacA/B carriage in Staphylococcus epidermidis associated with reduced susceptibility to chlorhexidine. S. epidermidis isolates positive for qacA/B were clonally diverse, although 65% of isolates belonged to the multidrug-resistant (MDR) clone ST2. These findings raise concerns in relation to the selection of MDR strains by chlorhexidine and are important in the context of recent evidence emphasising the benefits of targeting bloodstream infections associated with coagulase-negative staphylococci. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  10. MHC Expression on Spleen Lymphocyte Subsets in Genetically Resistant and Susceptible Chickens Infected with Marek's Disease Virus

    DEFF Research Database (Denmark)

    Dalgaard, Tina; Bøving, Mette K.; Handberg, Kurt

    2009-01-01

    Resistance and susceptibility to Marek's disease (MD) are strongly influenced by the chicken major histocompatibility complex (MHC). In this study, splenic lymphocytes from MD-resistant and MD-susceptible chickens of three MHC genotypes (B21/B21, B19/B21, and B19/B19) were analyzed by flow...... genotypes were subjected to infection with MD virus (GA strain) and spleen samples from infected as well as MHC-matched negative controls were analyzed at 1, 4, and 8 wk post-infection (p.i.). It was observed that MDV induced an increase in MHC class I expression late in the infection. Thus, MHC class I...

  11. Electrical Resistance Tomography Field Trials to Image CO2 Sequestration

    Science.gov (United States)

    Newmark, R.

    2003-12-01

    , telluric noise can be comparable to the signal levels during periods of geomagnetic activity. Finally, instrumentation stability over long periods is necessary to follow trends in reservoir behavior for several years. Solutions to these and other problems will be presented along with results from the first two years of work at a producing field undergoing CO2 flood. If electrical resistance tomography (ERT) imaging can be performed using existing well casings as long electrodes, it will substantially reduce the cost to monitor CO2 sequestration. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

  12. A distinct boundary between the higher brain's susceptibility to ischemia and the lower brain's resistance.

    Directory of Open Access Journals (Sweden)

    C Devin Brisson

    Full Text Available Higher brain regions are more susceptible to global ischemia than the brainstem, but is there a gradual increase in vulnerability in the caudal-rostral direction or is there a discrete boundary? We examined the interface between `higher` thalamus and the hypothalamus the using live brain slices where variation in blood flow is not a factor. Whole-cell current clamp recording of 18 thalamic neurons in response to 10 min O2/glucose deprivation (OGD revealed a rapid anoxic depolarization (AD from which thalamic neurons do not recover. Newly acquired neurons could not be patched following AD, confirming significant regional thalamic injury. Coinciding with AD, light transmittance (LT imaging during whole-cell recording showed an elevated LT front that initiated in midline thalamus and that propagated into adjacent hypothalamus. However, hypothalamic neurons patched in paraventricular nucleus (PVN, n= 8 magnocellular and 12 parvocellular neurons and suprachiasmatic nucleus (SCN, n= 18 only slowly depolarized as AD passed through these regions. And with return to control aCSF, hypothalamic neurons repolarized and recovered their input resistance and action potential amplitude. Moreover, newly acquired hypothalamic neurons could be readily patched following exposure to OGD, with resting parameters similar to neurons not previously exposed to OGD. Thalamic susceptibility and hypothalamic resilience were also observed following ouabain exposure which blocks the Na(+/K(+ pump, evoking depolarization similar to OGD in all neuronal types tested. Finally, brief exposure to elevated [K(+]o caused spreading depression (SD, a milder, AD-like event only in thalamic neurons so SD generation is regionally correlated with strong AD. Therefore the thalamus-hypothalamus interface represents a discrete boundary where neuronal vulnerability to ischemia is high in thalamus (like more rostral neocortex, striatum, hippocampus. In contrast hypothalamic neurons are

  13. SUSCEPTIBILITY OF RIFAMPICIN-ISONIAZID RESISTANT MYCOBACTERIUM TUBERCULOSIS ISOLATES AGAINST LEVOFLOXACIN

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    A. H. Kurniawan

    2016-01-01

    Full Text Available Background: Tuberculosis (TB is a high burden disease in Indonesia with multidrug-resistant (MDR TB incidence started to increase. Treatment success of MDR-TB globally was low in number than it was targeted which was especially caused by fluoroquinolone resistance. One of the fluoroquinolone is levofloxacin, an antibiotic that has been widely used irrationally as antimicrobial treatment. Therefore, this study investigated the sensitivity and MBC of MDR Mycobacterium tuberculosis isolates against Levofloxacin. Method: The susceptibility test for MDR-Mycobacterium tuberculosis on levofloxacin by standard method with levofloxacin were on concentrations 0,5 μg/ml, 1 μg/ml, and 2 μg/ml. Sample of 8 strains MDR-Mycobacterium tuberculosis were cultured with each concentrations on Middlebrook 7H9 for 1 week incubation. Next, each of the incubated concentration was subcultured on solid media Middlebrook 7H10 for 3 weeks incubation. Colonized agar plates after 3 weeks incubation were confirmed with acid-fast stain. Results: On MB 7H10 with levofloxacin concentration 2 μg/ml showed bactericidal effect 100% by no MDR Mycobacterium tuberculosis colony grew (0/8 while the MB 7H10 with levofloxacin concentration 1 μg/ml and 0,5 μg/ml showed the bactericidal effect 37,5% and 25% respectively. The colonized agar plate implied that the MDR Mycobacterium tuberculosis with levofloxacin concentration 1 μg/ml (5/8 and 0,5 μg/ml (6/8 grew well. Conclusion: Levofloxacin concentration 2 μg/ml was susceptible on MDR Mycobacterium tuberculosis. The concentration 2 μg/ml of levofloxacin could be considered as MBC.

  14. Prevalence and antimicrobial susceptibility pattern of methicillin resistant Staphylococcus aureus isolates from Trinidad & Tobago

    Directory of Open Access Journals (Sweden)

    Monteil Michele

    2006-07-01

    Full Text Available Abstract Background Methicillin-resistant Staphylococcus aureus (MRSA has become increasingly prevalent worldwide since it was first reported in a British hospital. The prevalence however, varies markedly in hospitals in the same country, and from one country to another. We therefore sought to document comprehensively the prevalence and antimicrobial susceptibility pattern of MRSA isolates in Trinidad and Tobago. Methods All Staphylococcus aureus isolates encountered in routine clinical specimens received at major hospitals in the country between 2000 and 2001 were identified morphologically and biochemically by standard laboratory procedures including latex agglutination test (Staphaurex Plus; Murex Diagnostics Ltd; Dartford, England; tube coagulase test with rabbit plasma (Becton, Dickinson & Co; Sparks, MD, USA, and DNase test using DNase agar (Oxoid Ltd; Basingstoke, Hampshire, England. MRSA screening was performed using Mueller-Hinton agar containing 6 μg oxacillin and 4% NaCl, latex agglutination test (Denka Seiken Co. Ltd, Tokyo, Japan and E-test system (AB Biodisk, Solna, Sweden. Susceptibility to antimicrobial agents was determined by the modified Kirby Bauer disc diffusion method while methicillin MICs were determined with E-test system. Results Of 1,912 S. aureus isolates received, 12.8% were methicillin (oxacillin resistant. Majority of the isolates were recovered from wound swabs (86.9% and the least in urine (0.4% specimens. Highest number of isolates was encountered in the surgical (62.3% and the least from obstetrics and gynaecology (1.6% facilities respectively. Large proportions of methicillin sensitive isolates are >85% sensitive to commonly used and available antimicrobials in the country. All MRSA isolates were resistant to ceftriaxone, erythromycin, gentamicin and penicillin but were 100% sensitive to vancomycin, rifampin and chloramphenicol. Conclusion There is a progressive increase in MRSA prevalence in the country but

  15. Growth and Reproduction of Glyphosate-Resistant and Susceptible Populations of Kochia scoparia

    Science.gov (United States)

    Kumar, Vipan; Jha, Prashant

    2015-01-01

    Evolution of glyphosate-resistant kochia is a threat to no-till wheat-fallow and glyphosate-resistant (GR) cropping systems of the US Great Plains. The EPSPS (5-enol-pyruvylshikimate-3-phosphate synthase) gene amplification confers glyphosate resistance in the tested Kochia scoparia (L.) Schrad populations from Montana. Experiments were conducted in spring to fall 2014 (run 1) and summer 2014 to spring 2015 (run 2) to investigate the growth and reproductive traits of the GR vs. glyphosate-susceptible (SUS) populations of K. scoparia and to determine the relationship of EPSPS gene amplification with the level of glyphosate resistance. GR K. scoparia inbred lines (CHES01 and JOP01) exhibited 2 to 14 relative copies of the EPSPS gene compared with the SUS inbred line with only one copy. In the absence of glyphosate, no differences in growth and reproductive parameters were evident between the tested GR and SUS inbred lines, across an intraspecific competition gradient (1 to 170 plants m-2). GR K. scoparia plants with 2 to 4 copies of the EPSPS gene survived the field-use rate (870 g ha-1) of glyphosate, but failed to survive the 4,350 g ha-1 rate of glyphosate (five-times the field-use rate). In contrast, GR plants with 5 to 14 EPSPS gene copies survived the 4,350 g ha-1 of glyphosate. The results from this research indicate that GR K. scoparia with 5 or more EPSPS gene copies will most likely persist in field populations, irrespective of glyphosate selection pressure. PMID:26580558

  16. Deltamethrin-mediated survival, behavior, and oenocyte morphology of insecticide-susceptible and resistant yellow fever mosquitos (Aedes aegypti).

    Science.gov (United States)

    Marriel, Nadja Biondine; Tomé, Hudson Vaner Ventura; Guedes, Raul Carvalho Narciso; Martins, Gustavo Ferreira

    2016-06-01

    Insecticide use is the prevailing control tactic for the mosquito Aedes aegypti, a vector of several human viruses, which leads to ever-increasing problems of insecticide resistance in populations of this insect pest species. The underlying mechanisms of insecticide resistance may be linked to the metabolism of insecticides by various cells, including oenocytes. Oenocytes are ectodermal cells responsible for lipid metabolism and detoxification. The goal of this study was to evaluate the sublethal effects of deltamethrin on survival, behavior, and oenocyte structure in the immature mosquitoes of insecticide-susceptible and resistant strains of A. aegypti. Fourth instar larvae (L4) of both strains were exposed to different concentrations of deltamethrin (i.e., 0.001, 0.003, 0.005, and 0.007 ppm). After exposure, L4 were subjected to behavioral bioassays. Insecticide effects on cell integrity after deltamethrin exposure (at 0.003 or 0.005 ppm) were assessed by processing pupal oenocytes for transmission electron microscopy or TUNEL reaction. The insecticide resistant L4 survived all the tested concentrations, whereas the 0.007-ppm deltamethrin concentration had lethal effects on susceptible L4. Susceptible L4 were lethargic and exhibited less swimming activity than unexposed larvae, whereas the resistant L4 were hyperexcited following exposure to 0.005 ppm deltamethrin. No sublethal effects and no significant cell death were observed in the oenocytes of either susceptible or resistant insects exposed to deltamethrin. The present study illustrated the different responses of susceptible and resistant strains of A. aegypti following exposure to sublethal concentration of deltamethrin, and demonstrated how the behavior of the immature stage of the two strains varied, as well as oenocyte structure following insecticide exposure. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Fumigant toxicity of lemon eucalyptus oil constituents to acaricide-susceptible and acaricide-resistant Tetranychus urticae.

    Science.gov (United States)

    Han, Jun; Kim, Soon-Il; Choi, Byeoung-Ryeol; Lee, Sang-Guei; Ahn, Young-Joon

    2011-12-01

    This study was aimed at assessing the fumigant toxicity of 14 essential oil constituents from lemon eucalyptus, Eucalyptus citriodora Hook, and another ten known compounds to females of acaricide-susceptible, chlorfenapyr-resistant, fenpropathrin-resistant, pyridaben-resistant and abamectin-resistant strains of Tetranychus urticae Koch. Menthol (LC(50) , 12.9 µg cm(-3) ) was the most toxic compound, followed by citronellyl acetate (16.8 µg cm(-3) ), against the susceptible females. High toxicity was also produced by β-citronellol, citral, geranyl acetate and eugenol (LC(50) , 21.7-24.6 µg cm(-3) ). The fumigant toxicity of these compounds was almost identical against females from either of the susceptible and resistant strains, indicating that the compounds and acaricides do not share a common mode of action or elicit cross-resistance. Global efforts to reduce the level of highly toxic synthetic acaricides in the agricultural environment justify further studies on materials derived from lemon eucalyptus oil, particularly menthol and citronellyl acetate, as potential acaricides for the control of acaricide-resistant T. urticae as fumigants with contact action. Copyright © 2011 Society of Chemical Industry.

  18. Clinical Antibiotic-resistant Acinetobacter baumannii Strains with Higher Susceptibility to Environmental Phages than Antibiotic-sensitive Strains.

    Science.gov (United States)

    Chen, Li-Kuang; Kuo, Shu-Chen; Chang, Kai-Chih; Cheng, Chieh-Chen; Yu, Pei-Ying; Chang, Chih-Hui; Chen, Tren-Yi; Tseng, Chun-Chieh

    2017-07-24

    Antibiotic-resistant Acinetobacter baumannii is associated with nosocomial infections worldwide. Here, we used clinically isolated A. baumannii strains as models to demonstrate whether antibiotic resistance is correlated with an increased susceptibility to bacteriophages. In this study, 24 active phages capable of infecting A. baumannii were isolated from various environments, and the susceptibilities of both antibiotic-sensitive and antibiotic-resistant strains of A. baumannii to different phages were compared. In our study, a total of 403 clinically isolated A. baumannii strains were identified. On average, the phage infection percentage of the antibiotic-resistant A. baumannii strains was 84% (from 81-86%), whereas the infection percentage in the antibiotic-sensitive A. baumannii strains was only 56.5% (from 49-64%). In addition, the risk of phage infection for A. baumannii was significantly increased in the strains that were resistant to at least four antibiotics and exhibited a dose-dependent response (p-trend baumannii isolates, 75.6% were phage typeable. The results of phage typing might also reveal the antibiotic-resistant profiles of clinical A. baumannii strains. In conclusion, phage susceptibility represents an evolutionary trade-off in A. baumannii strains that show adaptations for antibiotic resistance, particularly in medical environments that have high antibiotic use.

  19. Pyrethroid resistance in Anopheles gambiae leads to increased susceptibility to the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana.

    Science.gov (United States)

    Howard, Annabel F V; Koenraadt, Constantianus J M; Farenhorst, Marit; Knols, Bart G J; Takken, Willem

    2010-06-16

    Entomopathogenic fungi are being investigated as a new mosquito control tool because insecticide resistance is preventing successful mosquito control in many countries, and new methods are required that can target insecticide-resistant malaria vectors. Although laboratory studies have previously examined the effects of entomopathogenic fungi against adult mosquitoes, most application methods used cannot be readily deployed in the field. Because the fungi are biological organisms it is important to test potential field application methods that will not adversely affect them. The two objectives of this study were to investigate any differences in fungal susceptibility between an insecticide-resistant and insecticide-susceptible strain of Anopheles gambiae sensu stricto, and to test a potential field application method with respect to the viability and virulence of two fungal species Pieces of white polyester netting were dipped in Metarhizium anisopliae ICIPE-30 or Beauveria bassiana IMI391510 mineral oil suspensions. These were kept at 27 +/- 1 degrees C, 80 +/- 10% RH and the viability of the fungal conidia was recorded at different time points. Tube bioassays were used to infect insecticide-resistant (VKPER) and insecticide-susceptible (SKK) strains of An. gambiae s.s., and survival analysis was used to determine effects of mosquito strain, fungus species or time since fungal treatment of the net. The resistant VKPER strain was significantly more susceptible to fungal infection than the insecticide-susceptible SKK strain. Furthermore, B. bassiana was significantly more virulent than M. anisopliae for both mosquito strains, although this may be linked to the different viabilities of these fungal species. The viability of both fungal species decreased significantly one day after application onto polyester netting when compared to the viability of conidia remaining in suspension. The insecticide-resistant mosquito strain was susceptible to both species of fungus

  20. Pyrethroid resistance in Anopheles gambiae leads to increased susceptibility to the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana

    Directory of Open Access Journals (Sweden)

    Knols Bart GJ

    2010-06-01

    Full Text Available Abstract Background Entomopathogenic fungi are being investigated as a new mosquito control tool because insecticide resistance is preventing successful mosquito control in many countries, and new methods are required that can target insecticide-resistant malaria vectors. Although laboratory studies have previously examined the effects of entomopathogenic fungi against adult mosquitoes, most application methods used cannot be readily deployed in the field. Because the fungi are biological organisms it is important to test potential field application methods that will not adversely affect them. The two objectives of this study were to investigate any differences in fungal susceptibility between an insecticide-resistant and insecticide-susceptible strain of Anopheles gambiae sensu stricto, and to test a potential field application method with respect to the viability and virulence of two fungal species Methods Pieces of white polyester netting were dipped in Metarhizium anisopliae ICIPE-30 or Beauveria bassiana IMI391510 mineral oil suspensions. These were kept at 27 ± 1°C, 80 ± 10% RH and the viability of the fungal conidia was recorded at different time points. Tube bioassays were used to infect insecticide-resistant (VKPER and insecticide-susceptible (SKK strains of An. gambiae s.s., and survival analysis was used to determine effects of mosquito strain, fungus species or time since fungal treatment of the net. Results The resistant VKPER strain was significantly more susceptible to fungal infection than the insecticide-susceptible SKK strain. Furthermore, B. bassiana was significantly more virulent than M. anisopliae for both mosquito strains, although this may be linked to the different viabilities of these fungal species. The viability of both fungal species decreased significantly one day after application onto polyester netting when compared to the viability of conidia remaining in suspension. Conclusions The insecticide-resistant

  1. Pyrazinamide Susceptibility and pncA Mutation Profiles of Mycobacterium tuberculosis among Multidrug-Resistant Tuberculosis Patients in Bangladesh.

    Science.gov (United States)

    Rahman, Arfatur; Ferdous, Sara Sabrina; Ahmed, Shahriar; Rahman, S M Mazidur; Uddin, Mohammad Khaja Mafij; Pholwat, Suporn; Gratz, Jean; Houpt, Eric; Banu, Sayera

    2017-09-01

    Pyrazinamide (PZA) is a frontline antituberculosis (anti-TB) drug used in both first- and second-line treatment regimens. However, due to complex laboratory requirements, the PZA susceptibility test is rarely performed, leading to a scarcity of data on susceptibility to PZA. Bangladesh is a country with a burden of high rates of both TB and multidrug-resistant TB (MDR-TB), but to our knowledge, published data on rates of PZA susceptibility (PZAs), especially among MDR-TB patients, are limited. We aimed to analyze the PZA susceptibility patterns of Mycobacterium tuberculosis isolates from MDR-TB patients and to correlate the pncA mutation with PZA resistance in Bangladesh. A total of 169 confirmed MDR M. tuberculosis isolates from a pool of specimens collected in a nationwide surveillance study were included in this analysis. All the isolates were tested for phenotypic PZA susceptibility in Bactec mycobacterial growth indicator tube (MGIT) culture medium, and the pncA gene was sequenced. We also correlated different types of clinical information and treatment outcomes with PZA susceptibility. We found that 45% of isolates were phenotypically PZA resistant. Sequencing of the pncA gene revealed a high concordance (82.2%) between the pncA gene sequence and the phenotypic assay results. A total of 64 different mutations were found, and 9 isolates harbored multiple mutations. We detected 27 new pncA mutations. We did not find any significant correlation between the different clinical categories, the genetic lineage, or treatment outcome group and PZA susceptibility. Considering the turnaround time, sequencing would be the more feasible option to determine PZA susceptibility, and further studies to investigate the MIC of PZA should be conducted to determine an effective dose of the drug. Copyright © 2017 Rahman et al.

  2. Trends towards Lower Antimicrobial Susceptibility and Characterization of Acquired Resistance among Clinical Isolates of Brachyspira hyodysenteriae in Spain ▿

    Science.gov (United States)

    Hidalgo, Álvaro; Carvajal, Ana; Vester, Birte; Pringle, Märit; Naharro, Germán; Rubio, Pedro

    2011-01-01

    The antimicrobial susceptibility of clinical isolates of Brachyspira hyodysenteriae in Spain was monitored, and the underlying molecular mechanisms of resistance were investigated. MICs of tylosin, tiamulin, valnemulin, lincomycin, and tylvalosin were determined for 87 B. hyodysenteriae isolates recovered from 2008 to 2009 by broth dilution. Domain V of the 23S rRNA gene and the ribosomal protein L3 gene were sequenced in 20 isolates for which the tiamulin MIC was ≥4 μg/ml, presenting decreased susceptibility, and in 18 tiamulin-susceptible isolates (MIC ≤ 0.125 μg/ml), and all isolates were typed by multiple-locus variable-number tandem repeats analysis. A comparison with antimicrobial susceptibility data from 2000 to 2007 showed an increase in pleuromutilin resistance over time, doubling the number of isolates with decreased susceptibility to tiamulin. No alteration in susceptibility was detected for lincomycin, and the MIC of tylosin remained high (MIC50 > 128 μg/ml). The decreased susceptibility to tylosin and lincomycin can be explained by mutations at position A2058 of the 23S rRNA gene (Escherichia coli numbering). A2058T was the predominant mutation, but A2058G also was found together with a change of the neighboring base pair at positions 2057 to 2611. The role of additional point mutations in the vicinity of the peptidyl transferase center and mutations in the L3 at amino acids 148 and 149 and their possible involvement in antimicrobial susceptibility are considered. An association between G2032A and high levels of tiamulin and lincomycin MICs was found, suggesting an increasing importance of this mutation in antimicrobial resistance of clinical isolates of B. hyodysenteriae. PMID:21555771

  3. Trends towards lower antimicrobial susceptibility and characterization of acquired resistance among clinical isolates of Brachyspira hyodysenteriae in Spain.

    Science.gov (United States)

    Hidalgo, Álvaro; Carvajal, Ana; Vester, Birte; Pringle, Märit; Naharro, Germán; Rubio, Pedro

    2011-07-01

    The antimicrobial susceptibility of clinical isolates of Brachyspira hyodysenteriae in Spain was monitored, and the underlying molecular mechanisms of resistance were investigated. MICs of tylosin, tiamulin, valnemulin, lincomycin, and tylvalosin were determined for 87 B. hyodysenteriae isolates recovered from 2008 to 2009 by broth dilution. Domain V of the 23S rRNA gene and the ribosomal protein L3 gene were sequenced in 20 isolates for which the tiamulin MIC was ≥ 4 μg/ml, presenting decreased susceptibility, and in 18 tiamulin-susceptible isolates (MIC ≤ 0.125 μg/ml), and all isolates were typed by multiple-locus variable-number tandem repeats analysis. A comparison with antimicrobial susceptibility data from 2000 to 2007 showed an increase in pleuromutilin resistance over time, doubling the number of isolates with decreased susceptibility to tiamulin. No alteration in susceptibility was detected for lincomycin, and the MIC of tylosin remained high (MIC(50) > 128 μg/ml). The decreased susceptibility to tylosin and lincomycin can be explained by mutations at position A2058 of the 23S rRNA gene (Escherichia coli numbering). A2058T was the predominant mutation, but A2058G also was found together with a change of the neighboring base pair at positions 2057 to 2611. The role of additional point mutations in the vicinity of the peptidyl transferase center and mutations in the L3 at amino acids 148 and 149 and their possible involvement in antimicrobial susceptibility are considered. An association between G2032A and high levels of tiamulin and lincomycin MICs was found, suggesting an increasing importance of this mutation in antimicrobial resistance of clinical isolates of B. hyodysenteriae.

  4. Evaluation of canine-specific minocycline and doxycycline susceptibility breakpoints for meticillin-resistant Staphylococcus pseudintermedius isolates from dogs.

    Science.gov (United States)

    Hnot, Melanie L; Cole, Lynette K; Lorch, Gwendolen; Papich, Mark G; Rajala-Schultz, Paivi J; Daniels, Joshua B

    2015-10-01

    Using the US Clinical and Laboratory Standards Institute (CLSI) human tetracycline breakpoints to predict minocycline and doxycycline susceptibility of Staphylococcus pseudintermedius (SP) isolates from dogs is not appropriate because they are too high to meet pharmacokinetic/pharmacodynamic data using a standard dose. New breakpoints have been approved for doxycycline and proposed for minocycline. Revised breakpoints are four dilutions lower than tetracycline breakpoints, providing a more conservative standard for classification of isolates. The objectives of this study were to measure minimum inhibitory concentrations (MICs) of minocycline and doxycycline of 100 canine meticillin-resistant SP clinical isolates, compare their susceptibilities to minocycline and doxycycline based on current and revised standards, and document their tetracycline resistance genes. E-test strips were used to determine MICs. PCR was used to identify tet genes. Using the human tetracycline breakpoint of MIC ≤ 4 μg/mL, 76 isolates were susceptible to minocycline and 36 isolates were susceptible to doxycycline. In contrast, using the proposed minocycline breakpoint (MIC ≤ 0.25 μg/mL) and approved doxycycline breakpoint (MIC ≤ 0.125 μg/mL), 31 isolates were susceptible to both minocycline and doxycycline. Thirty-one isolates carried no tet genes, two had tet(K) and 67 had tet(M). Use of the human tetracycline breakpoints misclassified 45 and five of the isolates as susceptible to minocycline and doxycycline, respectively. PCR analysis revealed that 43 and five of the isolates classified as susceptible to minocycline and doxycycline, respectively, possessed the tetracycline resistance gene, tet(M), known to confer resistance to both drugs. These results underscore the importance of utilizing the proposed minocycline and approved doxycycline canine breakpoints in place of human tetracycline breakpoints. © 2015 ESVD and ACVD.

  5. Pressure and temperature induced electrical resistance change in nano-carbon/epoxy composites

    NARCIS (Netherlands)

    Shen, J. T.; Buschhorn, S. T.; De Hosson, J. Th. M.; Schulte, K.; Fiedler, B.

    2015-01-01

    In this study, we investigate the changes of electrical resistance of the carbon black (CB) and carbon nanotube (CNT) filled epoxy composites upon compression, swelling and temperature variation. For all samples we observe a decrease of electrical resistance under compression, while an increase of

  6. Behavioral and Reproductive Response of White Pine Weevil (Pissodes strobi to Resistant and Susceptible Sitka Spruce (Picea sitchensis

    Directory of Open Access Journals (Sweden)

    Jeanne A. Robert

    2010-08-01

    Full Text Available White pine weevil (Pissodes strobi, Peck. is a native forest insect pest in the Pacific Northwest of North America that attacks species of spruce (Picea spp. and pine (Pinus spp.. Young Sitka spruce [Picea sitchensis (Bong. Carr.] trees are particularly susceptible to weevil attack. Pockets of naturally occurring Sitka spruce resistance have been identified in high weevil hazard areas in coastal British Columbia. In this study, we characterize behavioral, physiological and reproductive responses of weevils to an extremely resistant Sitka spruce genotype (H898 in comparison to a highly susceptible genotype (Q903. The experiments relied on a large number of three-year-old clonally propagated trees and were therefore restricted to two contrasting Sitka spruce genotypes. When exposed to resistant trees, both male and female weevils were deterred during host selection and mating, females showed delayed or reduced ovary development, and successful reproduction of weevils was prevented on resistant trees.

  7. A laboratory study of the correlation between the thermal conductivity and electrical resistivity of soil

    Science.gov (United States)

    Wang, Jie; Zhang, Xiaopei; Du, Lizhi

    2017-10-01

    Thermal conductivity k (Wm- 1 K- 1) and electrical resistivity ρ (Ω·m) depend on common parameters such as grain size, dry density and saturation, allowing the finding of a relationship between both parameters. In this paper, we found a linear quantitative formula between thermal conductivity and electrical resistivity of soil. To accomplish this, we measured the thermal conductivity and electrical resistivity of 57 soil samples in the laboratory; samples included 8 reconstructed soils from the Changchun area (clay, silt, and sand) with approximately 7 different saturation levels. A linear relationship between thermal conductivity and electrical resistivity was found excluding the parameter of soil saturation, and the linear model was validated with undisturbed soils in Changchun area. To fully use this relationship (e.g., by imaging the thermal conductivity of soils with electrical resistivity tomography), further measurements with different soils are needed.

  8. Electrical resistivity characteristics of diesel oil-contaminated kaolin clay and a resistivity-based detection method.

    Science.gov (United States)

    Liu, Zhibin; Liu, Songyu; Cai, Yi; Fang, Wei

    2015-06-01

    As the dielectric constant and conductivity of petroleum products are different from those of the pore water in soil, the electrical resistivity characteristics of oil-contaminated soil will be changed by the corresponding oil type and content. The contaminated soil specimens were manually prepared by static compaction method in the laboratory with commercial kaolin clay and diesel oil. The water content and dry density of the first group of soil specimens were controlled at 10 % and 1.58 g/cm(3). Corresponding electrical resistivities of the contaminated specimens were measured at the curing periods of 7, 14, and 28 and 90, 120, and 210 days on a modified oedometer cell with an LCR meter. Then, the electrical resistivity characteristics of diesel oil-contaminated kaolin clay were discussed. In order to realize a resistivity-based oil detection method, the other group of oil-contaminated kaolin clay specimens was also made and tested, but the initial water content, oil content, and dry density were controlled at 0~18 %, 0~18 %, 1.30~1.95 g/cm(3), respectively. Based on the test data, a resistivity-based artificial neural network (ANN) was developed. It was found that the electrical resistivity of kaolin clay decreased with the increase of oil content. Moreover, there was a good nonlinear relationship between electrical resistivity and corresponding oil content when the water content and dry density were kept constant. The decreasing velocity of the electrical resistivity of oil-contaminated kaolin clay was higher before the oil content of 12 % than after 12 %, which indicated a transition of the soil from pore water-controlled into oil-controlled electrical resistivity characteristics. Through microstructural analysis, the decrease of electrical resistivity could be explained by the increase of saturation degree together with the collapse of the electrical double layer. Environmental scanning electron microscopy (ESEM) photos indicated that the diesel oil

  9. Genetic variation between Biomphalaria alexandrina snails susceptible and resistant to Schistosoma mansoni infection.

    Science.gov (United States)

    El-Nassery, Suzanne M F; Abou-El-Naga, Iman F; Allam, Sonia R; Shaat, Eman A; Mady, Rasha F M

    2013-01-01

    Much effort has been made to control schistosomiasis infection in Egypt. However, enduring effects from such strategies have not yet been achieved. In this study, we sought to determine the genetic variability related to the interaction between Biomphalaria alexandrina snails and Schistosoma mansoni. Using RAPD-PCR with eight (10 mers) random primers, we were able to determine the polymorphic markers that differed between snails susceptible and resistant to Schistosoma mansoni infection using five primers out of the eight. Our results suggest that the RAPD-PCR technique is an efficient means by which to compare genomes and to detect genetic variations between schistosomiasis intermediate hosts. The RAPD technique with the above-noted primers can identify genomic markers that are specifically related to the Biomphalaria alexandrina/Schistosoma mansoni relationship in the absence of specific nucleotide sequence information. This approach could be used in epidemiologic surveys to investigate genetic diversity among Biomphalaria alexandrina snails. The ability to determine resistant markers in Biomphalaria alexandrina snails could potentially lead to further studies that use refractory snails as agents to control the spread of schistosomiasis.

  10. Resistance and susceptibility of mandarins and their hybrids to Alternaria alternata

    Directory of Open Access Journals (Sweden)

    Camilla de Andrade Pacheco

    2012-12-01

    Full Text Available Caused by Alternaria alternata, Alternaria brown spot (ABS is a major fungal disease of mandarins in Brazil, causing serious losses in commercial orchards of Ponkan tangerine (Citrus reticulata Blanco and Murcott tangor [C. sinensis (L. Osbeck × C. reticulata Blanco]. The response of 31 accessions/genotypes of mandarins and their hybrids to A. alternata, was evaluated in São Paulo state, Brazil. The incidence and severity of the disease in fruit were evaluated in the field, using diagrammatic scale, four times during 2008 and 2009. Based on these data, the area under the disease progress curve (AUDPC was calculated. In parallel, in vivo and in vitro inoculations with A. alternata were made on leaves to confirm field results. Resistance and susceptibility was evaluated in controlled experiments by counting the number of lesions per leaf using a diagrammatic scale. Most of the genotypes were symptomatic after inoculation with A. alternata with disease most severe on the hybrids Nova, África do Sul, Ponkan and Murcott. Cultivars like Cravo, Nules and Ortanique that have excellent fruit quality and had lower AUDPCs, whereas Fremont and Thomas were highly resistant to the fungus and did not show any symptoms in the field or in controlled inoculations. The attractiveness and pronounced flavor of Fremont and Thomas fruit make them new options for the citriculture.

  11. Genetic Variation between Biomphalaria alexandrina Snails Susceptible and Resistant to Schistosoma mansoni Infection

    Directory of Open Access Journals (Sweden)

    Suzanne M. F. El-Nassery

    2013-01-01

    Full Text Available Much effort has been made to control schistosomiasis infection in Egypt. However, enduring effects from such strategies have not yet been achieved. In this study, we sought to determine the genetic variability related to the interaction between Biomphalaria alexandrina snails and Schistosoma mansoni. Using RAPD-PCR with eight (10 mers random primers, we were able to determine the polymorphic markers that differed between snails susceptible and resistant to Schistosoma mansoni infection using five primers out of the eight. Our results suggest that the RAPD-PCR technique is an efficient means by which to compare genomes and to detect genetic variations between schistosomiasis intermediate hosts. The RAPD technique with the above-noted primers can identify genomic markers that are specifically related to the Biomphalaria alexandrina/Schistosoma mansoni relationship in the absence of specific nucleotide sequence information. This approach could be used in epidemiologic surveys to investigate genetic diversity among Biomphalaria alexandrina snails. The ability to determine resistant markers in Biomphalaria alexandrina snails could potentially lead to further studies that use refractory snails as agents to control the spread of schistosomiasis.

  12. Identification and control of a gentamicin resistant, meticillin susceptible Staphylococcus aureus outbreak on a neonatal unit

    Science.gov (United States)

    Davies, Bethany; Menson, Esse; Klein, John L; Watts, Timothy L; Kearns, Angela M; Pichon, Bruno; Edgeworth, Jonathan D; French, Gary L

    2014-01-01

    We describe the identification and control of an outbreak of gentamicin resistant, meticillin susceptible Staphylococcus aureus (GR-MSSA) on a 36-bed neonatal unit (NNU) in London. Control measures included admission and weekly screening for GR-MSSA, cohorting affected babies, environmental and staff screening, hydrogen peroxide vapour (HPV) for terminal disinfection of cohort rooms, and reinforcement of hand hygiene. Seventeen babies were affected by the outbreak strain over ten months; seven were infected and ten were asymptomatic carriers. The outbreak strain was gentamicin resistant and all isolates were indistinguishable by pulsed-field gel electrophoresis. The outbreak strains spread rapidly and were associated with a high rate of bacteraemia (35% of 17 affected patients had bacteraemia vs. 10% of 284 patients with MSSA prior to the outbreak, p=0.007). None of 113 staff members tested were colonised with GR-MSSA. GR-MSSA was recovered from 11.5% of 87 environmental surfaces in cohort rooms, 7.1% of 28 communal surfaces and 4.1% of 74 surfaces after conventional terminal disinfection. None of 64 surfaces sampled after HPV decontamination yielded GR-MSSA. Recovery of GR-MSSA from two high level sites suggested that the organism could have been transmitted via air. Occasional breakdown in hand hygiene compliance and contaminated environmental surfaces probably contributed to transmission. PMID:28989367

  13. In-vitro susceptibility of methicillin-resistant Stayphylococcus aureus to honey.

    Science.gov (United States)

    Hussain, Muhammad Barkaat; Hannan, Abdul; Absar, Muhammad; Butt, NadeemShafique

    2017-05-01

    Wound infections caused by methicillin-resistant Staphylococcus aureus (MRSA) is becoming much complicated and costly to treat as antimicrobial resistance is quite common. Twenty five MRSA strains isolated from infected wounds and three ATCC reference strains were evaluated for their susceptibility to locally produced black seed (Nigella sativa), beri (ZiziphusJujuba) and shain honey (Plectranthus rugosus wall) by agar incorporation assay. Medically graded manuka honey (UMF 21 + ) was included as control. Locally produced black seed honey inhibited all clinical isolates at mean MIC of 5.5% (v/v), whereas manuka honey at mean MIC of 4.4% (v/v). The other two locally produced honey; beri and shain honey inhibited these isolates at 6.4% and 10.4% (v/v) respectively. The result of the study has demonstrated that indigenous black seed honey has comparable antibacterial activity to manuka honey and thus offers a good new addition to the existing honey resource for the treatment of wound infections. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Antimicrobial Susceptibility and Molecular Epidemiology of Multidrug-Resistant Klebsiella pneumoniae in Central China.

    Science.gov (United States)

    Guo, Xiaobing; Cao, Zaiqiu; Dai, Zhifeng; Li, Yuan; He, Xiaohong; Hu, Xiaoxin; Tian, Fuyun; Ren, Yihui

    2017-05-24

    Extended-spectrum-beta-lactamase-producing and carbapenemase-producing Klebsiella pneumoniae strains have rapidly spread through clinical units worldwide. This study investigated the epidemiology and resistance profiles of K. pneumoniae strains isolated in central China between 2009 and 2014. Antimicrobial susceptibility testing and polymerase chain reaction were used to investigate the prevalence of extended-spectrum beta-lactamases (ESBL) and carbapenemase production by these K. pneumoniae strains, and the prevalence of K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae was investigated by multilocus sequence typing. Carbapenem resistance has emerged as a major concern in K. pneumoniae infections, as phenotype testing has detected carbapenemases in nearly 20% of isolates. KPC-producing isolates in a local epidemic were clonally related, with ST11 being the reservoir for the bla KPC-2 gene and ESBL genes. During the 6-year collection period, the prevalence of ESBLs was dynamic, and suggested that bla CTX-M-55 might become prevalent in the future. Our findings demonstrate the high prevalence of carbapenemase- and ESBL-producing K. pneumoniae in central China and predict a future local epidemic of KPC-2 and CTX-M-55.

  15. Susceptibility and resistance to ethanol in Saccharomyces strains isolated from wild and fermentative environments.

    Science.gov (United States)

    Arroyo-López, F N; Salvadó, Z; Tronchoni, J; Guillamón, J M; Barrio, E; Querol, A

    2010-12-01

    In this work, we apply statistical modelling techniques to study the influence of increasing concentrations of ethanol on the overall growth of 29 yeast strains belonging to different Saccharomyces and non-Saccharomyces species. A modified Gompertz equation for decay was used to objectively estimate the noninhibitory concentration (NIC) and minimum inhibitory concentration (MIC) for the assayed strains to ethanol, which are related to the susceptibility and resistance of yeasts to this compound, respectively. A first ANOVA analysis, grouping strains as a function of their respective Saccharomyces species, revealed that S. cerevisiae was the yeast with the highest, and statistically significant, ethanol resistance value. Then, a second factorial ANOVA analysis, using the origin of strains (wild or fermentative) and their taxonomic classification (S. cerevisiae, S. paradoxus or S. bayanus var. uvarum) as categorical predictor variables, showed that no significant differences for the NIC and MIC parameters were found between both ecological niches within the same species, indicative that these physiological characteristics were presumably not modified throughout the adaptation to human-manipulated fermentative environments. Finally, differences among selected strains with respect to ethanol tolerance were correlated to the initial contents of unsaturated fatty acids, mainly oleic acid. Copyright © 2010 John Wiley & Sons, Ltd.

  16. Permethrin resistance variation and susceptible reference line isolation in a field population of the mosquito, Culex quinquefasciatus (Diptera: Culicidae).

    Science.gov (United States)

    Yang, Ting; Liu, Nannan

    2014-10-01

    This study examines the genetic variations and mechanisms involved in the development of permethrin resistance in individual mosquitoes from a field population of Culex quinquefasciatus, HAmCq(G0) , and characterizes susceptible reference lines of mosquitoes with a similar genetic background to the field HAmCq(G0) strain. Six upregulated cytochrome P450 genes, CYP9M10, CYP9J34, CYP6P14, CYP9J40, CYP6AA7, and CYP4C52v1, previously identified as being upregulated in the larvae of resistant HAmCq(G8) mosquitoes were examined in the larvae of 3 strains (susceptible S-Lab, parental HAmCq(G0) and permethrin-selected highly resistant HAmCq(G8) ) and 8 HAmCq(G0) single-egg raft colonies, covering a range of levels of susceptibility/resistance to permethrin and exhibiting different variations in the expression of A and/or T alleles at the L-to-F kdr locus of the sodium channel. The 2 lines with the lowest tolerance to permethrin and bearing solely the susceptible A allele at the L-to-F kdr locus of the sodium channels, from colonies Cx_SERC5 and Cx_SERC8, showed lower or similar levels of all 6 of the P450 genes tested compared with the S-Lab strain, suggesting that these 2 lines could be used as the reference mosquitoes in future studies characterizing insecticide resistance in HAmCq mosquitoes. This study also provides a detailed investigation of the mechanisms involved in insecticide resistance in individuals within a population: individuals with elevated levels of resistance to permethrin all displayed one or more potential resistance mechanisms-either elevated levels of P450 gene expression, or L-to-F mutations in the sodium channel, or both. © 2013 Institute of Zoology, Chinese Academy of Sciences.

  17. Molecular characterization of lipoamide dehydrogenase gene in Trypanosoma cruzi populations susceptible and resistant to benznidazole.

    Science.gov (United States)

    Dos Santos, Paula F; Moreira, Douglas S; Baba, Elio H; Volpe, Caroline M O; Ruiz, Jerônimo C; Romanha, Alvaro J; Murta, Silvane M F

    2016-11-01

    Lipoamide dehydrogenase (LipDH) is a flavin-containing disulfide oxidoreductase from the same group of thioredoxin reductase, glutathione reductase and trypanothione reductase. This enzyme is found in the mitochondria of all aerobic organisms where it takes part in at least three important multienzyme complexes from the citric acid cycle. In this study, we performed a phylogenetic analysis comparing the amino acid sequence of the LipDH from Trypanosoma cruzi (TcLipDH) with the LipDH from other organisms. Subsequently, the copy number of the TcLipDH gene, the mRNA and protein levels, and the enzymatic activity of the LipDH were determined in populations and strains of T. cruzi that were either resistant or susceptible to benznidazole (BZ). In silico analysis showed the presence of two TcLipDH alleles in the T. cruzi genome. It also showed that TcLipDH protein has less than 55% of identity in comparison to the human LipDH, but the active site is conserved in both of them. Southern blot results suggest that the TcLipDH is a single copy gene in the genome of the T. cruzi samples analyzed. Northern blot assays showed one transcript of 2.4 kb in all T. cruzi populations. Northern blot and Real Time RT-PCR data revealed that the TcLipDH mRNA levels were 2-fold more expressed in the BZ-resistant T. cruzi population (17LER) than in its susceptible pair (17WTS). Western blot results revealed that the TcLipDH protein level is 2-fold higher in 17LER sample in comparison to 17WTS sample. In addition, LipDH activity was higher in the 17LER population than in the 17WTS. Sequencing analysis revealed that the amino acid sequences of the TcLipDH from 17WTS and 17LER populations are identical. Our findings show that one of the mechanisms associated with in vitro-induced BZ resistance to T. cruzi correlates with upregulation of LipDH enzyme. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Efficacy of oral moxidectin against susceptible and resistant isolates of Dirofilaria immitis in dogs

    Directory of Open Access Journals (Sweden)

    Tom L. McTier

    2017-11-01

    Full Text Available Abstract Background Monthly topical and sustained-release injectable formulations of moxidectin are currently marketed; however, an oral formulation, while approved at a dose of 3 μg/kg, is not currently marketed in the United States. Although resistance of heartworms to all macrocyclic lactone (ML heartworm preventives (ivermectin, milbemycin, selamectin and moxidectin has been demonstrated, to date no data have been reported on the effectiveness of oral moxidectin against recent isolates of Dirofilaria immitis. Methods A total of nine studies were conducted to determine the efficacy of moxidectin against a range of older and recently sourced heartworm isolates. Dogs (groups of three to eight were inoculated with 50 D. immitis infective larvae (L3 from nine different isolates (MP3, Michigan, JYD-34, ZoeMO-2012, ZoeKy-2013, ZoeLA-2013, GCFL-2014, AMAL-2014 and ZoeAL-2015 and treated 28–30 days later with single oral doses of 3 μg/kg of moxidectin. Additionally, one group of dogs that was inoculated with JYD-34 was treated monthly for 3 consecutive months beginning 30 days post inoculation. Dogs were held for approximately 4 months after the initial (or only treatment and then necropsied for recovery of adult heartworms. Results A single dose of 3 μg/kg of moxidectin was 100% effective in preventing the development of five of nine heartworm isolates (MP3, Michigan, ZoeKy, GCFL and ZoeAL isolates, confirming their susceptibility to oral moxidectin at this dose. MP3 and Michigan are isolates sourced from the field more than 9 years ago, while ZoeKy, ZoeAL and GCFL were isolated from the field within the past 2 to 3 years. Against JYD-34, ZoeMO, ZoeLA and AMAL isolates, a single dose of 3 μg/kg of moxidectin was not completely effective, with efficacies of 19%, 82%, 54% and 62%, respectively, demonstrating resistance of these heartworm isolates to oral moxidectin at this dosage. Three consecutive monthly doses of 3 μg/kg of

  19. Molecular and Growth-Based Drug Susceptibility Testing of Mycobacterium tuberculosis Complex for Ethambutol Resistance in the United States

    Directory of Open Access Journals (Sweden)

    Mitchell A. Yakrus

    2016-01-01

    Full Text Available Ethambutol (EMB is used as a part of drug regimens for treatment of tuberculosis (TB. Susceptibility of Mycobacterium tuberculosis complex (MTBC isolates to EMB can be discerned by DNA sequencing to detect mutations in the embB gene associated with resistance. US Public Health Laboratories (PHL primarily use growth-based drug susceptibility test (DST methods to determine EMB resistance. The Centers for Disease Control and Prevention (CDC provides a service for molecular detection of drug resistance (MDDR by DNA sequencing and concurrent growth-based DST using agar proportion. PHL and CDC test results were compared for 211 MTBC samples submitted to CDC from September 2009 through February 2011. Concordance between growth-based DST results from PHL and CDC was 88.2%. A growth-based comparison of 39 samples, where an embB mutation associated with EMB resistance was detected, revealed a higher percentage of EMB resistance by CDC (84.6% than by PHL (59.0% which was significant (P value = 0.002. Discordance between all growth-based test results from PHL and CDC was also significant (P value = 0.003. Most discordance was linked to false susceptibility using the BACTEC™ MGIT™ 960 (MGIT growth-based system. Our analysis supports coalescing growth-based and molecular results for an informed interpretation of potential EMB resistance.

  20. Molecular identification of abomasal bacteria associated with genetic resistance and susceptibility to Haemonchus contortus infection in sheep

    Directory of Open Access Journals (Sweden)

    Adriane Holtz Tirabassi

    2016-12-01

    Full Text Available The widespread occurrence of anthelmintic-resistant gastrointestinal nematodes (GINs, particularly Haemonchus contortus, in sheep production systems has magnified the need to identify and develop alternative control strategies. Strategies include the selection of genetically GIN-resistant sheep and the implementation of biological parasite control to reduce dependence on anthelmintic drugs. In this study, we aimed to establish the molecular identity of bacterial communities present in the abomasum of sheep classified as resistant or susceptible to H. contortus, an abomasal parasite. Thirty-eight sheep were experimentally infected with L3 Haemonchus contortus and analyzed for fecal egg count (FEC and hematocrit (Ht to establish haemonchosis resistance or susceptibility. Four resistant sheep (RS and four susceptible sheep (SS were selected for microbial sampling and subsequent phylogenetic analysis. Molecular identification of the bacteria was based on amplification of the bacterial 16S rRNA gene, construction of a 16S rDNA clone library, and subsequent gene sequencing. Significant differences (p = 0.05 were observed in the occurrence of different phyla identified in RS and SS libraries: Firmicutes (61.4% and 37.2%, respectively, Proteobacteria (10.2% and 37.2%, respectively, Bacteroidetes (12.8% and 5.8%, respectively, and unclassified bacteria (12.8% and 17%, respectively. Differences between the proportions of bacterial communities present in the RS and SS pool samples were observed, contributing as a first step toward the assessment of the association between the gastrointestinal tract microbiota and nematode resistance in sheep.

  1. Predicting and tracking spatiotemporal moments in electrical resistivity tomography

    Science.gov (United States)

    Ward, W. O. C.; Wilkinson, P. B.; Chambers, J.; Bai, L.

    2015-12-01

    Visualisation is an invaluable tool in the study of near sub-surface processes, whether by mathematical modelling or by geophysical imaging. Quantitative analysis can further assist interpretation of the ongoing physical processes, and it is clear that any reliable model should take direct observations into account. Using electrical resistivity tomography (ERT), localised areas can be surveyed to produce 2-D and 3-D time-lapse images. This study investigates combining quantitative results obtained via ERT with spatio-temporal motion models in tracer experiments to interpret and predict fluid flow. As with any indirect imaging technique, ERT suffers specific issues with resolution and smoothness as a result of its inversion process. In addition, artefacts are typical in the resulting volumes. Mathematical models are also a source of uncertainty - and in combining these with ERT images, a trade-off must be made between the theoretical and the observed. Using computational imaging, distinct regions of stable resistivity can be directly extracted from a time-slice of an ERT volume. The automated nature, as well the potential for more than one region-of-interest, means that multiple regions can be detected. Using Kalman filters, it is possible to convert the detections into a process state, taking into account pre-defined models and predicting progression. In consecutive time-steps, newly detected features are assigned, where possible, to existing predictions to create tracks that match the tracer model. Preliminary studies looked at a simple motion model, tracking the centre of mass of a tracer plume with assumed constant velocity and mean resistivity. Extending the model to factor in spatial distribution of the plume, an oriented semi-axis is used to represent the centralised second-order moment, with an increasing factor of magnitude to represent the plume dispersion. Initial results demonstrate the efficacy of the approach, significantly improving reliability as the

  2. Identification of genes differentially expressed during interaction of resistant and susceptible apple cultivars (Malus × domestica) with Erwinia amylovora

    Science.gov (United States)

    2010-01-01

    Background The necrogenic enterobacterium, Erwinia amylovora is the causal agent of the fire blight (FB) disease in many Rosaceaespecies, including apple and pear. During the infection process, the bacteria induce an oxidative stress response with kinetics similar to those induced in an incompatible bacteria-plant interaction. No resistance mechanism to E. amylovora in host plants has yet been characterized, recent work has identified some molecular events which occur in resistant and/or susceptible host interaction with E. amylovora: In order to understand the mechanisms that characterize responses to FB, differentially expressed genes were identified by cDNA-AFLP analysis in resistant and susceptible apple genotypes after inoculation with E. amylovora. Results cDNA were isolated from M.26 (susceptible) and G.41 (resistant) apple tissues collected 2 h and 48 h after challenge with a virulent E. amylovora strain or mock (buffer) inoculated. To identify differentially expressed transcripts, electrophoretic banding patterns were obtained from cDNAs. In the AFLP experiments, M.26 and G.41 showed different patterns of expression, including genes specifically induced, not induced, or repressed by E. amylovora. In total, 190 ESTs differentially expressed between M.26 and G.41 were identified using 42 pairs of AFLP primers. cDNA-AFLP analysis of global EST expression in a resistant and a susceptible apple genotype identified different major classes of genes. EST sequencing data showed that genes linked to resistance, encoding proteins involved in recognition, signaling, defense and apoptosis, were modulated by E. amylovora in its host plant. The expression time course of some of these ESTs selected via a bioinformatic analysis has been characterized. Conclusion These data are being used to develop hypotheses of resistance or susceptibility mechanisms in Malus to E. amylovora and provide an initial categorization of genes possibly involved in recognition events, early

  3. Specific adjustments in grapevine leaf proteome discriminating resistant and susceptible grapevine genotypes to Plasmopara viticola

    DEFF Research Database (Denmark)

    Figueiredo, Andreia; Martins, Joana; Sebastiana, Mónica

    2017-01-01

    Grapevine downy mildew is an important disease affecting crop production leading to severe yield losses. This study aims to identify the grapevine cultivar-specific adjustments of leaf proteome that allow the discrimination between resistance and susceptibility towards P. viticola (constitutive (...

  4. Waste disposal mapping with electrical resistivity tomography case: Leuwigajah landfill

    Science.gov (United States)

    Aryanti, Erisha; Ardi, Ahmad Puji; Almunziri, Muaz; Xanggam, Zael Yahd; Eleazar, Adino; Widodo

    2017-07-01

    Leuwigajah landfill as administrative is located between district of Bandung and Cimahi citythat has an environmental and social problem that caused aquifer contamination due to the big amount of waste from Bandung city, Cimahi and Bandung regency. It is occupied in abandoned andesite mine site with an area of about 25 hectare. The aim of this research is to map the geology structure and to study the leachate towards aquifer layer below Leuwigajah landfill. Here, we present the study of Leuwigajah landfill subsurface using Electrical Resistivity Tomography (ERT). ERT is one of the most promising prospecting techniques mainly concerning its effective contribution to resolve several environmental problems, was applied for the geophysical modeling. ERT is a robust imaging method the theory and implementation of which are well documented in geophysical research literature. The geological setting comprises clayed weathered layer, fractured andesitic dike. Due to the above-mentioned geological singularity and in the light of the requirement for an environmentally safe construction of the landfill, an ERT survey was carried out with dipole-dipole array, 78 m of acquisition line and 6 m of electrode spacing. The model consists of 4 layers below the Leuwigajah landfill and andesitic fracture until depth of 18.7 m below the surface.

  5. Strength and electrical resistivity of heavily worked copper

    Science.gov (United States)

    Springs, J. C.; Kao, Y. T.; Srivastava, A.; Levin, Z. S.; Barber, R. E.; Hartwig, K. T.

    2017-12-01

    Copper and its alloys are a topic of interest for various cryogenic conductor applications. Often, it is used as a supporting matrix for superconducting filaments requiring that it have good strength and high conductivity. One of the best methods to increase strength while preserving conductivity is work hardening. In this study, CDA101, CDA110, and C182 copper were processed by a severe plastic deformation (SPD) procedure called equal channel angular extrusion (ECAE). In this study we explore the relationships between the levels of plastic strain and annealing with tensile and hardness properties, grain size, and electrical resistivity. While C182 has the highest strength, it also has the lowest conductivity. CDA101 and CDA110 both retain over 95% of their conductivity in the fully worked state, while C182 has about 40% of the IACS value. Saturation of strength occurs around 3-4 ECAE passes. It is concluded that a lower amount of plastic strain via ECAE is best for creating a material with the highest combination of strength and conductivity, and is suitable for high strength high conductivity applications.

  6. Electrical Resistivity Measurement of Petroleum Coke Powder by Means of Four-Probe Method

    Science.gov (United States)

    Rouget, G.; Majidi, B.; Picard, D.; Gauvin, G.; Ziegler, D.; Mashreghi, J.; Alamdari, H.

    2017-10-01

    Carbon anodes used in Hall-Héroult electrolysis cells are involved in both electrical and chemical processes of the cell. Electrical resistivity of anodes depends on electrical properties of its constituents, of which carbon coke aggregates are the most prevalent. Electrical resistivity of coke aggregates is usually characterized according to the ISO 10143 standardized test method, which consists of measuring the voltage drop in the bed of particles between two electrically conducing plungers through which the current is also applied. Estimation of the electrical resistivity of coke particles from the resistivity of particle bed is a challenging task and needs consideration of the contribution of the interparticle void fraction and the particle/particle contact resistances. In this work, the bed resistivity was normalized by subtracting the interparticle void fraction. Then, the contact size was obtained from discrete element method simulation and the contact resistance was calculated using Holm's theory. Finally, the resistivity of the coke particles was obtained from the bed resistivity.

  7. Biofilm formation and susceptibility to gentamicin and colistin of extremely drug-resistant KPC-producing Klebsiella pneumoniae.

    Science.gov (United States)

    Naparstek, Livnat; Carmeli, Yehuda; Navon-Venezia, Shiri; Banin, Ehud

    2014-04-01

    KPC-producing Klebsiella pneumoniae (KPC-Kpn) is a worldwide challenging pathogen, yet its biofilm-forming potential is not defined. We characterized biofilm formation of this pathogen and determined biofilm susceptibility to gentamicin and colistin. Forty-six KPC-Kpn clinical isolates were studied [sequence type (ST) 258, n = 28; and other STs, n = 18]. Biofilm biomass was determined using the standard assay measured by OD590 (where OD stands for optical density) and visualized using confocal microscopy. Antibiotic effect on biofilm formation was evaluated and susceptibility within biofilm was determined by the minimal biofilm elimination concentration (MBEC) method. KPC-Kpn isolates produced biofilm in the range of 0.02-0.3 OD590, where ST258 isolates produced less biofilm compared with other STs (median OD590 0.07 versus 0.15, respectively; P resistant to gentamicin compared with other STs (resistance rates: 14% versus 66%, respectively; P Gentamicin-resistant isolates (MIC ≥ 32 mg/L) showed a dramatic increase in resistance within the biofilm (up to 234-fold), whereas gentamicin-susceptible isolates (MIC gentamicin resistance was not due to overexpression of the aminoglycoside resistance gene aac(3)-II in the biofilm state. Resistance to colistin in biofilm increased as well, but was less prominent (P gentamicin and colistin, regardless of the genetic lineage. KPC-Kpn and particularly ST258 do not form massive biofilms. Nevertheless, susceptibility to gentamicin of this endemic lineage is retained in its biofilm state, supporting the use of this antibiotic in the clinical scenario.

  8. Immunological responses and cytokine gene expression analysis to Cooperia punctata infections in resistant and susceptible Nelore cattle.

    Science.gov (United States)

    Bricarello, P A; Zaros, L G; Coutinho, L L; Rocha, R A; Silva, M B; Kooyman, F N J; De Vries, E; Yatsuda, A P; Amarante, A F T

    2008-08-01

    Cellular and humoral immune response, as well as cytokine gene expression, was assessed in Nelore cattle with different degrees of resistance to Cooperia punctata natural infection. One hundred cattle (male, weaned, 11-12 months old), kept together on pasture, were evaluated. Faecal and blood samples were collected for parasitological and immunological assays. Based on nematode faecal egg counts (FEC) and worm burden, the seven most resistant and the eight most susceptible animals were selected. Tissue samples of the small intestine were collected for histological quantification of inflammatory cells and analysis of cytokine gene expression (IL-2, IL-4, IL-8, IL-12p35, IL-13, TNF-alpha, IFN-gamma, MCP-1, MCP-2, and MUC-1) using real-time RT-PCR. Mucus samples were also collected for IgA levels determination. Serum IgG1 mean levels against C. punctata antigens were higher in the resistant group, but significant differences between groups were only observed 14 days after the beginning of the experiment against infective larvae (L3) and 14 and 84 days against adult antigens. The resistant group also presented higher IgA levels against C. punctata (L3 and adult) antigens with significant difference 14 days after the beginning of the trial (P<0.05). In the small-intestine mucosa, levels of IgA anti-L3 and anti-adult C. punctata were higher in the resistant group, compared with the susceptible group (P<0.05). Gene expression of both T(H)2 cytokines (IL-4 and IL-13) in the resistant group and T(H)1 cytokines (IL-2, IL-12p35, IFN-gamma and MCP-1) in the susceptible group was up-regulated. Such results suggested that immune response to C. punctata was probably mediated by T(H)2 cytokines in the resistant group and by T(H)1 cytokines in the susceptible group.

  9. Study of Different Effects of Nets Impregnated with Different Pyrethroids on Susceptible and Resistant Strains of Anopheles stephensi

    Directory of Open Access Journals (Sweden)

    M.H. Hodjati

    2006-10-01

    Full Text Available Introduction & Objectives: A laboratory study was carried out to investigate the insecticidal, irritant and anti-feeding effects of nets treated with various pyrethroids against susceptible and highly pyrethroid resistant strains of An. stephensi. Materials & Methods: Tests were carried out inside a mosquito cage measuring 25×25×25 cm where mosquitoes were offered the opportunity to feed blood on an arm through the top face of the cage which had been pyrethroid treated.Results: With all the pyrethroids tested, the resistant strain spent a longer time in contact with a treated net, which was in contact with a human arm, than did the susceptible strain. With permethrin the resistant strain fed significantly more successfully through the treated netting than did the susceptible strain. With deltamethrin there was a non-significant tendency in the same direction in comparing the two strains. However, with alphacypermethrin there was a non-significant tendency in the reverse direction. After 15 min in the cage which tested for the ability to feed through a pyrethroid treated net, observed mortality was higher with the susceptible than the resistant strain. Conclusion: Thus there was no sign that the longer resting of the resistant strain on treated netting would compensate for the fact that a higher dose was needed to kill this strain. Such compensation had been suggested with the West African An. gambiae where treated nets continue to work well against a highly resistant wild population. However this does not seem to apply to our resistant An. stephens.

  10. Use of cefuroxime for women with community-onset acute pyelonephritis caused by cefuroxime-susceptible or -resistant Escherichia coli.

    Science.gov (United States)

    Chang, U-Im; Kim, Hyung Wook; Wie, Seong-Heon

    2016-01-01

    Efforts to decrease the use of extended-spectrum cephalosporins are required to prevent the selection and transmission of multi-drug resistant pathogens, such as extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. The objectives of this study were to assess the clinical efficacy of intravenous cefuroxime as an empirical antibiotic for the treatment of hospitalized women with acute pyelonephritis (APN) caused by Escherichia coli. We analyzed the clinical and microbiologic database of 328 hospitalized women with community-onset APN. Of 328 women with APN, 22 patients had cefuroxime-resistant E. coli APN, and 306 patients had cefuroxime-susceptible E. coli APN. The early clinical success rates were significantly higher (p = 0.001) in the cefuroxime-susceptible group (90.8%, 278/306) than in the cefuroxime-resistant group (68.2%, 15/22) at 72 hours. The clinical cure rates at 4 to 14 days after completing antimicrobial therapy were not significantly different in the cefuroxime-resistant or -susceptible groups, with 88.2% (15/17) and 97.8% (223/228; p = 0.078), respectively. The microbiological cure rates were not significantly different and were 90.9% (10/11) and 93.4% (128/137), respectively (p = 0.550). The median duration of hospitalization in the cefuroxime-resistant and -susceptible groups was 10 days (interquartile range [IQR], 8 to 13) and 10 days (IQR, 8 to 14), respectively (p =0.319). Cefuroxime, a second-generation cephalosporin, can be used for the initial empirical therapy of community-onset APN if tailored according to uropathogen identification and susceptibility results, especially in areas where the prevalence rate of ESBL-producing uropathogens is low.

  11. Electrical Resistance Based Damage Modeling of Multifunctional Carbon Fiber Reinforced Polymer Matrix Composites

    Science.gov (United States)

    Hart, Robert James

    In the current thesis, the 4-probe electrical resistance of carbon fiber-reinforced polymer (CFRP) composites is utilized as a metric for sensing low-velocity impact damage. A robust method has been developed for recovering the directionally dependent electrical resistivities using an experimental line-type 4-probe resistance method. Next, the concept of effective conducting thickness was uniquely applied in the development of a brand new point-type 4-probe method for applications with electrically anisotropic materials. An extensive experimental study was completed to characterize the 4-probe electrical resistance of CFRP specimens using both the traditional line-type and new point-type methods. Leveraging the concept of effective conducting thickness, a novel method was developed for building 4-probe electrical finite element (FE) models in COMSOL. The electrical models were validated against experimental resistance measurements and the FE models demonstrated predictive capabilities when applied to CFRP specimens with varying thickness and layup. These new models demonstrated a significant improvement in accuracy compared to previous literature and could provide a framework for future advancements in FE modeling of electrically anisotropic materials. FE models were then developed in ABAQUS for evaluating the influence of prescribed localized damage on the 4-probe resistance. Experimental data was compiled on the impact response of various CFRP laminates, and was used in the development of quasi- static FE models for predicting presence of impact-induced delamination. The simulation-based delamination predictions were then integrated into the electrical FE models for the purpose of studying the influence of realistic damage patterns on electrical resistance. When the size of the delamination damage was moderate compared to the electrode spacing, the electrical resistance increased by less than 1% due to the delamination damage. However, for a specimen with large

  12. Vancomycin resistant enterococci in urine cultures: Antibiotic susceptibility trends over a decade at a tertiary hospital in the United Kingdom

    Directory of Open Access Journals (Sweden)

    Liam Toner

    2016-03-01

    Full Text Available Purpose: Enterococci are a common cause of urinary tract infection and vancomycin-resistant strains are more difficult to treat. The purpose of this surveillance program was to assess the prevalence of and determine the risk factors for vancomycin resistance in adults among urinary isolates of Enterococcus sp. and to detail the antibiotic susceptibility profile, which can be used to guide empirical treatment. Materials and Methods: From 2005 to 2014 we retrospectively reviewed 5,528 positive Enterococcus sp. urine cultures recorded in a computerized laboratory results database at a tertiary teaching hospital in Cambridge, United Kingdom. Results: Of these cultures, 542 (9.8% were vancomycin resistant. No longitudinal trend was observed in the proportion of vancomycin- resistant strains over the course of the study. We observed emerging resistance to nitrofurantoin with rates climbing from near zero to 40%. Ampicillin resistance fluctuated between 50% and 90%. Low resistance was observed for linezolid and quinupristin/ dalfopristin. Female sex and inpatient status were identified as risk factors for vancomycin resistance. Conclusions: The incidence of vancomycin resistance among urinary isolates was stable over the last decade. Although resistance to nitrofurantoin has increased, it still serves as an appropriate first choice in uncomplicated urinary tract infection caused by vancomycin- resistant Enterococcus sp.

  13. Electrical resistivity and spatial variation in agriculture terraces: statistical correlation between ert and flow direction algorithms

    Directory of Open Access Journals (Sweden)

    Fernandes J.

    2017-02-01

    Full Text Available The construction of earthen embankment terraces in the Douro Region raises a set of problems related to hydrological processes. The main objective of this study is the evaluation of the spatial variation of electrical resistivity in agriculture terraces at Douro valley (Portugal. To achieve this objective, two variables are analysed, the soil electrical resistivity and the flow direction algorithm. In a field survey we recorded 13 electrical resistivity profiles. The contributing area was calculated with the algorithms D∞ (Deterministic Infinity Flow and MFD (Multiple Flow Direction and the results are the base of the internal runoff modelling, both supported by the digital elevation model with a spatial resolution of 1m2. A correlation between the spatial variation of the soil electrical resistivity represented by the standard deviation of the electrical resistivity for each profile and the average value of the contributing area coincident with each profile was established. The electrical resistivity standard deviation seems to be moderately well correlated according to the D∞ algorithm at about 1m of depth, and it has a good correlation at 1,5m to 2m of depth with the MFD algorithm. Taken together, the results show a significant positive statistical correlation between the electrical resistivity standard deviation and the contributing areas (MFD and D∞ depending on the soil depth.

  14. Synergistic effects of tacrolimus and azole antifungal compounds in fluconazole-susceptible and fluconazole-resistant Candida glabrata isolates

    Directory of Open Access Journals (Sweden)

    Laura Bedin Denardi

    2015-03-01

    Full Text Available In vitro interaction between tacrolimus (FK506 and four azoles (fluconazole, ketoconazole, itraconazole and voriconazole against thirty clinical isolates of both fluconazole susceptible and -resistant Candida glabrata were evaluated by the checkerboard microdilution method. Synergistic, indifferent or antagonism interactions were found for combinations of the antifungal agents and FK506. A larger synergistic effect was observed for the combinations of FK506 with itraconazole and voriconazole (43%, followed by that of the combination with ketoconazole (37%, against fluconazole-susceptible isolates. For fluconazole-resistant C. glabrata, a higher synergistic effect was obtained from FK506 combined with ketoconazole (77%, itraconazole (73%, voriconazole (63% and fluconazole (60%. The synergisms that we observed in vitro, notably against fluconazole-resistant C. glabrata isolates, are promising and warrant further analysis of their applications in experimental in vivo studies.

  15. The influence of changes in water content on the electrical resistivity of a natural unsaturated loess

    CERN Document Server

    Munoz-Castelblanco, José; Delage, Pierre; Cui, Yu Jun

    2013-01-01

    Non-destructive methods of measuring water content in soils have been extensively developed in the last decades, especially in soil science. Among these methods, the measurements based on the electrical resistivity are simple and reliable thanks to the clear relationship between the water content and the electrical resistivity of soils. In this work, a new electrical resistivity probe was developed to monitor the change in local water content in the triaxial apparatus. The probe is composed of two-pair of electrodes, and an electrical current is induced through the soil at the vicinity of the contact between the probe and the specimen. Some experimental data on the changes in resistivity with the degree of saturation were obtained in specimens of a natural unsaturated loess from Northern France. Two theoretical models of resistivity were also used to analyze the obtained data. Results are finally discussed with respect to the loess's water retention properties.

  16. Comparative study of genes expressed from rice fungus-resistant and susceptible lines during interactions with Magnaporthe oryzae.

    Science.gov (United States)

    Shi, Bu-Jun; Wang, Guo-Liang

    2008-12-31

    Rice blast disease caused by Magnaporthe oryzae is the most important fungal disease of rice. To understand the molecular basis of interaction between the fungus and rice, we constructed a cDNA library from a rice-resistant line inoculated with M. oryzae. One hundred and fifty-three cDNA clones were sequence analyzed, of which 129 exhibited significant nucleotide sequence homology to known genes, 21 were homologous to unknown genes, while three clones did not match to any database. However, these three unmatched clones showed sequence homology at protein level in the protein databases and one of them encoded a disease resistance-related protein kinase and was abundant in the EST collection. Northern analysis showed that this disease resistance-related protein kinase gene was induced by inoculation and only expressed in the rice-resistant, but not susceptible, lines. Southern analysis showed that this gene was present in a single copy in the rice genome and co-segregated with the M. oryzae resistance in the cross of the resistant and susceptible lines. This study illustrates that sequencing of ESTs from inoculated resistant plants can reveal genes responsive to pathogen infection, which could help understand plant defense mechanisms.

  17. Magnetic susceptibility, resistivity and 151Eu Mössbauer studies on Zn-substituted EuBa 2Cu 3O 7-y

    Science.gov (United States)

    Tomy, C. V.; Nagarajan, R.; Malik, S. K.; Prasad, Ram; Soni, N. C.; Adhikary, Kalyan

    1990-07-01

    Magnetic susceptibility, electrical resistivity and 151Eu Mossbauer studies have been performed on the compounds EuBa 2(Cu 1-xZn x) 3O 7-y with x = 0.0, 0.025, 0.05, 0.075 and 0.1. The parent compound, EuBa 2Cu 3O 7-y, is superconducting with zero resistance temperature (T c) of 88K. T c is strongly depressed as Zn is substituted for Cu in this system, the compounds with x > 0.05 being non superconducting down to 12K. 151Eu Mossbauer studies at 295K show a single Mossbauer line with isomer shift value typical of Eu 3+ ion in all the compounds, irrespective of the fact whether these are superconducting or not. Further, the isomer shift values are nearly independent of both the Zn concentration and the temperatures down to 10K. These observations imply that the CuO network responsible for superconductivity is very weakly coupled to the Eu sublattice. Magnetic susceptibility measurements show Van Vleck paramagnetism associated with Eu 3+ ions, except for an upturn at low temperatures.

  18. Tigecycline susceptibility and the role of efflux pumps in tigecycline resistance in KPC-producing Klebsiella pneumoniae.

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    Fang He

    Full Text Available KPC-producing Klebsiella pneumoniae isolates have emerged as important pathogens of nosocomial infections, and tigecycline is one of the antibiotics recommended for severe infections caused by KPC-producing K. pneumoniae. To identify the susceptibility profile of KPC-producing K. pneumoniae to tigecycline and investigate the role of efflux pumps in tigecycline resistance, a total of 215 KPC-producing K. pneumoniae isolates were collected. The minimum inhibitory concentration (MIC of tigecycline was determined by standard broth microdilution tests. Isolates showing resistance to tigecycline underwent susceptibility test with efflux pump inhibitors. Expression levels of efflux pump genes (acrB and oqxB and their regulators (ramA, marA, soxS and rarA were examined by real-time PCR, and the correlation between tigecycline MICs and gene expression levels were analysed. Our results show that the tigecycline resistance rate in these isolates was 11.2%. Exposure of the tigecycline-resistant isolates to the efflux pump inhibitor NMP resulted in an obvious decrease in MICs and restored susceptibility to tigecycline in 91.7% of the isolates. A statistically significant association between acrB expression and tigecycline MICs was observed, and overexpression of ramA was found in three tigecycline-resistant isolates, further analysis confirmed ramR mutations existed in these isolates. Transformation of one mutant with wild-type ramR restored susceptibility to tigecycline and repressed overexpression of ramA and acrB. These data indicate that efflux pump AcrAB, which can be up-regulated by ramR mutations and subsequent ramA activation, contributed to tigecycline resistance in K. pneumoniae clinical isolates.

  19. In vitro resistance of clinical Fusarium species to amphotericin B and voriconazole using the EUCAST antifungal susceptibility method.

    Science.gov (United States)

    Taj-Aldeen, Saad J; Salah, Husam; Al-Hatmi, Abdullah M S; Hamed, Manal; Theelen, Bart; van Diepeningen, Anne D; Boekhout, Teun; Lass-Flörl, Cornelia

    2016-08-01

    Susceptibility testing using the EUCAST-AFST method against 39 clinical Fusarium strains consecutively collected from local and invasive infections during the last 10years assessed the in vitro activities of amphotericin B (AmB) and triazole antifungal agents. In addition, the susceptibility pattern of 12 reference strains from the CBS-KNAW Fungal Biodiversity Centre (CBS) was evaluated. In particular Fusarium petroliphilum and F. solani sensu lato were involved in disseminated infections and known for treatment failure. AmB displayed the lowest MICs followed by voriconazole VRC, posaconazole (POC). Itraconazole (ITC) showed high MIC values, displaying in vitro resistance. Clinical isolates were significantly (P antifungal therapy. Resistant profiles to AmB and VRC, which are the currently recommended agents in the guidelines for treatments, and a late diagnosis may be associated with high mortality rate in immunocompromised patients. The present antifungal susceptibility profiles showed that species- and strain-specific differences in antifungal susceptibility exist within Fusarium and that susceptibility testing is important and may improve the prognosis of these infections. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. The infection processes of Sclerotinia sclerotiorum in cotyledon tissue of a resistant and a susceptible genotype of Brassica napus

    Science.gov (United States)

    Garg, Harsh; Li, Hua; Sivasithamparam, Krishnapillai; Kuo, John; Barbetti, Martin J.

    2010-01-01

    Background and Aims Sclerotinia sclerotiorum can attack >400 plant species worldwide. Very few studies have investigated host–pathogen interactions at the plant surface and cellular level in resistant genotypes of oilseed rape/canola (Brassica napus). Methods Infection processes of S. sclerotiorum were examined on two B. napus genotypes, one resistant cultivar ‘Charlton’ and one susceptible ‘RQ001-02M2’ by light and scanning electron microscopy from 2 h to 8 d post-inoculation (dpi). Key Results The resistant ‘Charlton’ impeded fungal growth at 1, 2 and 3 dpi, suppressed formation of appresoria and infection cushions, caused extrusion of protoplast from hyphal cells and produced a hypersensitive reaction. At 8 dpi, whilst in ‘Charlton’ pathogen invasion was mainly confined to the upper epidermis, in the susceptible ‘RQ001-02M2’, colonization up to the spongy mesophyll cells was evident. Calcium oxalate crystals were found in the upper epidermis and in palisade cells in susceptible ‘RQ001-02M2’ at 6 dpi, and throughout leaf tissues at 8 dpi. In resistant ‘Charlton’, crystals were not observed at 6 dpi, whereas at 8 dpi they were mainly confined to the upper epidermis. Starch deposits were also more prevalent in ‘RQ001-02M2’. Conclusions This study demonstrates for the first time at the cellular level that resistance to S. sclerotiorum in B. napus is a result of retardation of pathogen development, both on the plant surface and within host tissues. The resistance mechanisms identified in this study will be useful for engineering disease-resistant genotypes and for developing markers for screening for resistance against this pathogen. PMID:20929899

  1. In vitro antimicrobial susceptibility and genetic resistance determinants of Streptococcus agalactiae isolated from mastitic cows in Brazilian dairy herds

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    Juliana Rosa da Silva

    2017-08-01

    Full Text Available Streptococcus agalactiae is one of the main causative agents of bovine mastitis and is associated with several economic losses for producers. Few studies have evaluated antimicrobial susceptibility and the prevalence of genetic resistance determinants among isolates of this bacterium from Brazilian dairy cattle. This work aimed to evaluate the frequency of the antimicrobial resistance genes ermA, ermB, mefA, tetO, tetM, aphA3, and aad-6, and in vitro susceptibility to the antimicrobials amikacin, erythromycin, clindamycin, tetracycline, gentamicin, penicillin, ceftiofur, and cefalotin, and the associations between resistance genotypes and phenotypes among 118 S. agalactiae isolates obtained from mastitic cows in Brazilian dairy herds. Of the resistance genes examined, ermB was found in 19 isolates (16.1%, tetO in 23 (19.5%, and tetM in 24 (20.3%. The genes ermA, mefA, aphA3, and aad-6 were not identified. There was an association between the presence of genes ermB, tetM, and tetO and phenotypic resistance to erythromycin, clindamycin, and tetracycline. Rates of resistance to the tested antibiotics varied, as follows: erythromycin (19.5%, tetracycline (35.6%, gentamicin (9.3%, clindamycin (20.3%, penicillin (3.4%, and amikacin (38.1%; conversely, all isolates were susceptible to ceftiofur and cefalotin. Antimicrobial resistance testing facilitates the treatment decision process, allowing the most judicious choice of antibiotics. Moreover, it enables regional and temporal monitoring of the resistance dynamics of this pathogen of high importance to human and animal health.

  2. Staphylococcus aureus ocular infection: methicillin-resistance, clinical features, and antibiotic susceptibilities.

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    Chih-Chun Chuang

    Full Text Available BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA infection is an important public health issue. The study aimed to determine the prevalence of ocular infections caused by MRSA and to identify the clinical characteristics and antibiotic susceptibility of ocular MRSA infections by comparing those of ocular methicillin-sensitive S. aureus (MSSA infections. METHODOLOGY/PRINCIPAL FINDINGS: The medical records of the patients (n = 519 with culture-proven S. aureus ocular infections seen between January 1, 1999 and December 31, 2008 in Chang Gung Memorial Hospital were retrospectively reviewed. Two hundred and seventy-four patients with MRSA and 245 with MSSA ocular infections were identified. The average rate of MRSA in S. aureus infections was 52.8% and the trend was stable over the ten years (P value for trend  = 0.228. MRSA ocular infections were significantly more common among the patients with healthcare exposure (P = 0.024, but 66.1% (181/274 patients with MRSA ocular infections had no healthcare exposure. The most common clinical presentation for both MRSA and MSSA ocular infections was keratitis; MRSA and MSSA caused a similar disease spectrum except for lid infections. MRSA was significantly more resistant than MSSA to clindamycin, erythromycin and sulfamethoxazole/trimethoprim (all P<0.001. CONCLUSIONS/SIGNIFICANCE: We demonstrated a paralleled trend of ocular MRSA infection in a highly prevalent MRSA country by hospital-based survey. Except for lid disorder, MRSA shared similar spectrum of ocular pathology with MSSA. Since S. aureus is a common ocular pathogen, our results raise clinician's attention to the existence of highly prevalent MRSA.

  3. Staphylococcus aureus Ocular Infection: Methicillin-Resistance, Clinical Features, and Antibiotic Susceptibilities

    Science.gov (United States)

    Tan, Hsin-Yuan; Ma, David Hui-Kang; Lin, Ken-Kuo; Chang, Chee-Jen; Huang, Yhu-Chering

    2012-01-01

    Background Methicillin-resistant Staphylococcus aureus (MRSA) infection is an important public health issue. The study aimed to determine the prevalence of ocular infections caused by MRSA and to identify the clinical characteristics and antibiotic susceptibility of ocular MRSA infections by comparing those of ocular methicillin-sensitive S. aureus (MSSA) infections. Methodology/Principal Findings The medical records of the patients (n = 519) with culture-proven S. aureus ocular infections seen between January 1, 1999 and December 31, 2008 in Chang Gung Memorial Hospital were retrospectively reviewed. Two hundred and seventy-four patients with MRSA and 245 with MSSA ocular infections were identified. The average rate of MRSA in S. aureus infections was 52.8% and the trend was stable over the ten years (P value for trend  = 0.228). MRSA ocular infections were significantly more common among the patients with healthcare exposure (P = 0.024), but 66.1% (181/274) patients with MRSA ocular infections had no healthcare exposure. The most common clinical presentation for both MRSA and MSSA ocular infections was keratitis; MRSA and MSSA caused a similar disease spectrum except for lid infections. MRSA was significantly more resistant than MSSA to clindamycin, erythromycin and sulfamethoxazole/trimethoprim (all PMRSA infection in a highly prevalent MRSA country by hospital-based survey. Except for lid disorder, MRSA shared similar spectrum of ocular pathology with MSSA. Since S. aureus is a common ocular pathogen, our results raise clinician’s attention to the existence of highly prevalent MRSA. PMID:22880135

  4. Toxoplasma gondii antigen SAG2A differentially modulates IL-1β expression in resistant and susceptible murine peritoneal cells.

    Science.gov (United States)

    Leal-Sena, Jamilly Azevedo; Dos Santos, Jane Lima; Dos Santos, Thaise Anne Rocha; de Andrade, Edson Mário; de Oliveira Mendes, Tiago Antônio; Santana, Juliano Oliveira; Mineo, Tiago Wilson Patriarca; Mineo, José Roberto; da Cunha-Júnior, Jair Pereira; Pirovani, Carlos Priminho

    2018-03-01

    The cell surface of Toxoplasma gondii is covered by antigens (SAGs) from the SRS family anchored by glycosylphosphatidylinositol (GPI) and includes antigens from the SAG2 family. Among these, the SAG2A surface antigen shows great potential in activating humoral responses and has been used in characterizing the acute phase of infection and in the serological diagnosis of toxoplasmosis. In this study, we aimed to evaluate rSAG2A-induced proteins in BALB/c and C57BL/c mice macrophages and to evaluate the phenotypic polarization induced in the process. We treated the peritoneal macrophages from mouse strains that were resistant or susceptible to T. gondii with rSAG2A to analyze their proteomic profile by mass spectrometry and systems biology. We also examined the gene expression of these cells by RT-qPCR using the phenotypic markers of M1 and M2 macrophages. Differences were observed in the expression of proteins involved in the inflammatory process in both resistant and susceptible cells, and macrophages were preferentially induced to obtain a pro-inflammatory immune response (M1) via the overexpression of IL-1β in mice susceptible to this parasite. These data suggest that the SAG2A antigen induces phenotypic and classical activation of macrophages in both resistant and susceptible strains of mice during the acute phase of the disease.

  5. Procedure for measuring electrical resistivity of anisotropic materials: A revision of the Montgomery method

    Science.gov (United States)

    dos Santos, C. A. M.; de Campos, A.; da Luz, M. S.; White, B. D.; Neumeier, J. J.; de Lima, B. S.; Shigue, C. Y.

    2011-10-01

    A procedure for determining the electrical resistivity of anisotropic materials is presented. It offers several improvements to the well-known Montgomery method. One improvement, in particular, is the ability to obtain the electrical resistivity for all three axes of an orthorhombic crystal analytically, rather than using the iterative approach suggested by Montgomery for the third axis. All necessary equations are derived and their application in determining the tensor components of the electrical resistivity is explained in detail. Measurements on isotropic specimens were executed in order to test the foundations of the method. Measurements on anisotropic samples are compared with measurements obtained by using the standard four-probe method, revealing good agreement.

  6. Nanomotion Detection Method for Testing Antibiotic Resistance and Susceptibility of Slow-Growing Bacteria.

    Science.gov (United States)

    Villalba, María Ines; Stupar, Petar; Chomicki, Wojciech; Bertacchi, Massimiliano; Dietler, Giovanni; Arnal, Laura; Vela, María Elena; Yantorno, Osvaldo; Kasas, Sandor

    2017-12-04

    Infectious diseases are caused by pathogenic microorganisms and are often severe. Time to fully characterize an infectious agent after sampling and to find the right antibiotic and dose are important factors in the overall success of a patient's treatment. Previous results suggest that a nanomotion detection method could be a convenient tool for reducing antibiotic sensitivity characterization time to several hours. Here, the application of the method for slow-growing bacteria is demonstrated, taking Bordetella pertussis strains as a model. A low-cost nanomotion device is able to characterize B. pertussis sensitivity against specific antibiotics within several hours, instead of days, as it is still the case with conventional growth-based techniques. It can discriminate between resistant and susceptible B. pertussis strains, based on the changes of the sensor's signal before and after the antibiotic addition. Furthermore, minimum inhibitory and bactericidal concentrations of clinically applied antibiotics are compared using both techniques and the suggested similarity is discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Antimicrobial susceptibility of non-enterococcal intrinsic glycopeptide-resistant Gram-positive organisms.

    Science.gov (United States)

    Vay, Carlos; Cittadini, Roxana; Barberis, Claudia; Hernán Rodríguez, Carlos; Perez Martínez, Herminia; Genero, Fabiana; Famiglietti, Angela

    2007-02-01

    Non-enterococcal Gram-positive bacteria that are intrinsically vancomycin-resistant have been infrequently isolated in association with serious infections. However, well-documented infections have lately been reported with increasing frequency. Because these organisms may be pathogens, we tested the MICs of 19 antimicrobial agents by the agar dilution method for predicting susceptibility. The activity of these antimicrobial agents was assessed against 28 strains (Lactobacillus rhamnosus, 6; Lactobacillus acidophilus, 1; Lactobacillus casei, 1; Lactobacillus fermentum, 2; Lactobacillus brevis, 1; Lactobacillus plantarum, 1; Weissella confusa, 2; Leuconostoc mesenteroides, 7; Leuconostoc lactis, 4; Pediococcus acidilactici, 2; Pediococcus pentosaceus, 1), isolated from clinical specimens in an Argentinian university hospital from 1997 to 2003. The MICs of penicillin for 67% of the Lactobacillus strains and 100% of the Leuconostoc spp. and Pediococcus spp. strains tested were in the 0.25-2 microg/mL range. Erythromycin was the most active antimicrobial overall. Multiresistance was observed in 2 strains (Lactobacillus rhamnosus, 1; Lactobacillus plantarum, 1).

  8. Rat Strain Differences in Susceptibility to Alcohol-Induced Chronic Liver Injury and Hepatic Insulin Resistance

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    Sarah M. DeNucci

    2010-01-01

    Full Text Available The finding of more severe steatohepatitis in alcohol fed Long Evans (LE compared with Sprague Dawley (SD and Fisher 344 (FS rats prompted us to determine whether host factors related to alcohol metabolism, inflammation, and insulin/IGF signaling predict proneness to alcohol-mediated liver injury. Adult FS, SD, and LE rats were fed liquid diets containing 0% or 37% (calories ethanol for 8 weeks. Among controls, LE rats had significantly higher ALT and reduced GAPDH relative to SD and FS rats. Among ethanol-fed rats, despite similar blood alcohol levels, LE rats had more pronounced steatohepatitis and fibrosis, higher levels of ALT, DNA damage, pro-inflammatory cytokines, ADH, ALDH, catalase, GFAP, desmin, and collagen expression, and reduced insulin receptor binding relative to FS rats. Ethanol-exposed SD rats had intermediate degrees of steatohepatitis, increased ALT, ADH and profibrogenesis gene expression, and suppressed insulin receptor binding and GAPDH expression, while pro-inflammatory cytokines were similarly increased as in LE rats. Ethanol feeding in FS rats only reduced IL-6, ALDH1–3, CYP2E1, and GAPDH expression in liver. In conclusion, susceptibility to chronic steatohepatitis may be driven by factors related to efficiency of ethanol metabolism and degree to which ethanol exposure causes hepatic insulin resistance and cytokine activation.

  9. Enamel crystals of mice susceptible or resistant to dental fluorosis: an AFM study

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    Marília Afonso Rabelo BUZALAF

    2014-06-01

    Full Text Available Objective: This study aimed to assess the overall apatite crystals profile in the enamel matrix of mice susceptible (A/J strain or resistant (129P3/J strain to dental fluorosis through analyses by atomic force microscopy (AFM. Material and Methods: Samples from the enamel matrix in the early stages of secretion and maturation were obtained from the incisors of mice from both strains. All detectable traces of matrix protein were removed from the samples by a sequential extraction procedure. The purified crystals (n=13 per strain were analyzed qualitatively in the AFM. Surface roughness profile (Ra was measured. Results: The mean (±SD Ra of the crystals of A/J strain (0.58±0.15 nm was lower than the one found for the 129P3/J strain (0.66±0.21 nm but the difference did not reach statistical significance (t=1.187, p=0.247. Crystals of the 129P3/J strain (70.42±6.79 nm were found to be significantly narrower (t=4.013, p=0.0013 than the same parameter measured for the A/J strain (90.42±15.86 nm. Conclusion: enamel crystals of the 129P3/J strain are narrower, which is indicative of slower crystal growth and could interfere in the occurrence of dental fluorosis.

  10. Cluster of Neisseria gonorrhoeae Isolates With High-level Azithromycin Resistance and Decreased Ceftriaxone Susceptibility, Hawaii, 2016.

    Science.gov (United States)

    Katz, Alan R; Komeya, Alan Y; Kirkcaldy, Robert D; Whelen, A Christian; Soge, Olusegun O; Papp, John R; Kersh, Ellen N; Wasserman, Glenn M; O'Connor, Norman P; O'Brien, Pamela S; Sato, Douglas T; Maningas, Eloisa V; Kunimoto, Gail Y; Tomas, Juval E

    2017-09-15

    The Centers for Disease Control and Prevention (CDC) currently recommends dual therapy with ceftriaxone and azithromycin for gonorrhea to ensure effective treatment and slow emergence of antimicrobial resistance. Since 2013, the prevalence of reduced azithromycin susceptibility increased in the United States; however, these strains were highly susceptible to cephalosporins. We identified a cluster of Neisseria gonorrhoeae isolates with high-level azithromycin resistance, several of which also demonstrated decreased ceftriaxone susceptibility. Eight N. gonorrhoeae isolates collected from 7 patients on Oahu, Hawaii, seen 21 April 2016 through 10 May 2016 underwent routine Etest antimicrobial susceptibility testing by the Hawaii Department of Health. All demonstrated elevated azithromycin minimum inhibitory concentrations (MICs) >256 μg/mL and elevated ceftriaxone MICs (≥0.125 μg/mL). Isolates were sent to the University of Washington and CDC for confirmatory agar dilution testing; sequence data were sent to CDC for analysis. All patients were interviewed and treated, and when possible, partners were interviewed, tested, and treated. All isolates had azithromycin MICs >16 µg/mL and 5 had ceftriaxone MICs = 0.125 µg/mL by agar dilution. All isolates were β-lactamase positive and were resistant to penicillin, tetracycline, and ciprofloxacin. Genomic analysis revealed genetic relatedness. No patients reported recent travel or antibiotic use, and no male patients reported male sex partners. All patients were successfully treated. This cluster of genetically related gonococcal isolates with decreased ceftriaxone susceptibility and high-level azithromycin resistance may bring the threat of treatment failure in the United States with the current recommended dual therapy one step closer.

  11. Penicillin-resistant, ampicillin-susceptible Enterococcus faecalis of hospital origin: pbp4 gene polymorphism and genetic diversity.

    Science.gov (United States)

    Conceição, Natália; da Silva, Lucas Emanuel Pinheiro; Darini, Ana Lúcia da Costa; Pitondo-Silva, André; de Oliveira, Adriana Gonçalves

    2014-12-01

    Despite the spread of penicillin-resistant, ampicillin-susceptible Enterococcus faecalis (PRASEF) isolates in diverse countries, the mechanisms leading to this unusual resistance phenotype have not yet been investigated. The aim of this study was to evaluate whether polymorphism in the pbp4 gene is associated with penicillin resistance in PRASEF isolates and to determine their genetic diversity. E. faecalis isolates were recovered from different clinical specimens of hospitalized patients from February 2006 to June 2010. The β-lactam minimal inhibitory concentrations (MICs) were determined by E-test®. The PCR-amplified pbp4 gene was sequenced with an automated sequencer. The genetic diversities of the isolates were established by PFGE (pulsed-field gel electrophoresis) and MLST (multilocus sequencing typing). Seventeen non-producing β-lactamase PRASEF and 10 penicillin-susceptible, ampicillin-susceptible E. faecalis (PSASEF) strains were analyzed. A single-amino-acid substitution (Asp-573→Glu) in the penicillin-binding domain was significantly found in all PRASEF isolates by sequencing of the pbp4 gene but not in the penicillin-susceptible isolates. In contrast to the PSASEF isolates, a majority of the PRASEFs had similar PFGE profiles. Six representative PRASEF isolates were resolved by MLST into ST9 and ST524 and belong to the globally dispersed clonal complex 9 (CC9). In conclusion, it appears quite likely that the amino acid alteration (Asp-573→Glu) found in the PBP4 of the Brazilian PRASEF isolates may account for their reduced susceptibility to penicillin, although other resistance mechanisms remain to be investigated. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Corrosion-resistant, electrically-conductive plate for use in a fuel cell stack

    Science.gov (United States)

    Carter, J David [Bolingbrook, IL; Mawdsley, Jennifer R [Woodridge, IL; Niyogi, Suhas [Woodridge, IL; Wang, Xiaoping [Naperville, IL; Cruse, Terry [Lisle, IL; Santos, Lilia [Lombard, IL

    2010-04-20

    A corrosion resistant, electrically-conductive, durable plate at least partially coated with an anchor coating and a corrosion resistant coating. The corrosion resistant coating made of at least a polymer and a plurality of corrosion resistant particles each having a surface area between about 1-20 m.sup.2/g and a diameter less than about 10 microns. Preferably, the plate is used as a bipolar plate in a proton exchange membrane (PEMFC) fuel cell stack.

  13. Electrical Properties of Materials for Elevated Temperature Resistance Strain Gage Application. Ph.D. Thesis

    Science.gov (United States)

    Lei, Jih-Fen

    1987-01-01

    The objective was to study the electrical resistances of materials that are potentially useful as resistance strain gages at 1000 C. Transition metal carbides and nitrides, boron carbide and silicon carbide were selected for the experimental phase of this research. Due to their low temperature coefficient of resistance and good stability, TiC, ZrC, B sub 4 C and beta-SiC are suggested as good candidates for high temperature resistance strain gage applications.

  14. Inhibition of Ganciclovir-Susceptible and -Resistant Human Cytomegalovirus Clinical Isolates by the Benzimidazole l-Riboside 1263W94

    Science.gov (United States)

    McSharry, James J.; McDonough, Ann; Olson, Betty; Talarico, Christine; Davis, Michele; Biron, Karen K.

    2001-01-01

    The average 50% inhibitory concentration (IC50) values for AD169 were 0.22 ± 0.09 μM 1263W94 and 5.36 ± 0.12 μM ganciclovir. For 35 human cytomegalovirus (HCMV) clinical isolates the average IC50 was 0.42 ± 0.09 μM 1263W94, and for 26 ganciclovir-susceptible HCMV clinical isolates the average IC50 was 3.78 ± 1.62 μM ganciclovir. Nine HCMV clinical isolates that were resistant to ganciclovir were completely susceptible to 1263W94. PMID:11687477

  15. COMPARATIVE STUDY OF THE MOTHER SPOROCYST OF SCHISTOSOMA MANSONI IN THE SUSCEPTIBLE AND RESISTANT SNAILS OF BIOMPHALARIA GLABRATA

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    I. B. KALHORO, S. JALALI1 AND S. A. SHAMI

    2007-04-01

    Full Text Available The comparative studies of the susceptible and resistant snails of Biomphalaria glabrata mass exposed to miracidia of Schistosoma mansoni were conducted from 1 to10 days post-exposure (DPE. Histological sections of 50 susceptible and 50 resistant snails revealed that many single, multiple, mature and migratory mother sporocysts were observed in the foot, head, lip, tentacle, mantle, anus, buccal mass, neck, kidney, oesophagus, respiratory epithelium of the lung and pericardial cavity of the heart of susceptible snails. Whereas, few single and multiple mother sporocysts were visible in the earlier mentioned first eight organs of the resistant snails throughout infection period. Single mother sporocyst was located in the foot, head, lip and tentacles of susceptible snails at 1-2 DPE. At 3 DPE, multiple mother sporocysts were found in the above organs, and very few of them were observed in the mantle and muscles of the anus of these snails. In the resistant snails, such mother sporocysts were only found in the tentacle and columellar muscles at 9 DPE. At few mother sporocysts reached the buccal mass of the susceptible snails at 4 DPE. Increasing in the number of the single and multiple mother sporocysts were observed in the foot, head and tentacles, whereas a few of them were also visible in the neck and kidney of these snails at 5 DPE. Most of the mother sporocysts grew further in the foot, head, tentacles, mantle and kidney and developed into the mature form at 6 DPE onwards. At 8 DPE, some mature mother sporocysts were observed in the above mentioned organs and oesophagus of these snails. In the foot, head, lip and tentacle at 8 DPE, tegument of mature mother sporocyst was ruptured due to the increase number, and size of the embryos, and a few of them migrated towards the deeper tissues of the organs of the body of the snails. At 9 and 10 DPE, most of the above types of mother sporocyst remained in the earlier mentioned organs, very few were

  16. Water content dynamics at plot scale - comparison of time-lapse electrical resistivity tomography monitoring and pore pressure modelling

    Science.gov (United States)

    Zieher, Thomas; Markart, Gerhard; Ottowitz, David; Römer, Alexander; Rutzinger, Martin; Meißl, Gertraud; Geitner, Clemens

    2017-01-01

    Physically-based dynamic modelling of shallow landslide susceptibility rests on several assumptions and simplifications. However, the applicability of physically-based models is only rarely tested in the field at the appropriate scale. This paper presents results of a spray irrigation experiment conducted on a plot of 100 m2 on an Alpine slope susceptible to shallow landsliding. Infiltrating precipitation applied at a constant rate (27.5 mm/h for 5.3 h) was monitored by means of 2D time-lapse electrical resistivity tomography, combined with time-domain reflectometry sensors installed at various depths. In addition, regolith characteristics were assessed by dynamic cone penetration tests using a light-weight cone penetrometer. The spray irrigation experiment resulted in a vertically progressing wetting front to a depth of 80-100 cm. Below that, the unconsolidated material was already saturated by rainfall in the previous days. The observed mean resistivity reduction attributed to infiltrating water during irrigation was scaled to pressure head. Mean variations in pore pressure were reproduced by a linear diffusion model also used in physically-based dynamic landslide susceptibility modelling. Sensitive parameters (hydraulic conductivity and specific storage) were tested over selected value ranges and calibrated. Calibrated parameter values are within published and experimentally derived ranges. The results of the comparison of observations and model results suggest that the model is capable of reproducing mean changes of pore pressure at a suitable scale for physically-based modelling of shallow landslide susceptibility. However, small-scale variations in pore pressure that may facilitate the triggering of shallow landslides are not captured by the model.

  17. Antimicrobial susceptibility and antibiotic resistance gene transfer analysis of foodborne, clinical, and environmental Listeria spp. isolates including Listeria monocytogenes.

    Science.gov (United States)

    Bertsch, David; Muelli, Mirjam; Weller, Monika; Uruty, Anaïs; Lacroix, Christophe; Meile, Leo

    2014-02-01

    The aims of this study were to assess antibiotic resistance pheno- and genotypes in foodborne, clinical, and environmental Listeria isolates, as well as to elucidate the horizontal gene transfer potential of detected resistance genes. A small fraction of in total 524 Listeria spp. isolates (3.1%) displayed acquired antibiotic resistance mainly to tetracycline (n = 11), but also to clindamycin (n = 4) and trimethoprim (n = 3), which was genotypically confirmed. In two cases, a tetracycline resistance phenotype was observed together with a trimethoprim resistance phenotype, namely in a clinical L. monocytogenes strain and in a foodborne L. innocua isolate. Depending on the applied guidelines, a differing number of isolates (n = 2 or n = 20) showed values for ampicillin that are on the edge between intermediate susceptibility and resistance. Transferability of the antibiotic resistance genes from the Listeria donors, elucidated in vitro by filter matings, was demonstrated for genes located on transposons of the Tn916 family and for an unknown clindamycin resistance determinant. Transfer rates of up to 10(-5) transconjugants per donor were obtained with a L. monocytogenes recipient and up to 10(-7) with an Enterococcus faecalis recipient, respectively. Although the prevalence of acquired antibiotic resistance in Listeria isolates from this study was rather low, the transferability of these resistances enables further spread in the future. This endorses the importance of surveillance of L. monocytogenes and other Listeria spp. in terms of antibiotic susceptibility. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  18. Resistant and susceptible responses in alfalfa (Medicago sativa) to bacterial stem blight caused by Pseudomonas syringae pv. syringae.

    Science.gov (United States)

    Nemchinov, Lev G; Shao, Jonathan; Lee, Maya N; Postnikova, Olga A; Samac, Deborah A

    2017-01-01

    Bacterial stem blight caused by Pseudomonas syringae pv. syringae is a common disease of alfalfa (Medicago sativa L). Little is known about host-pathogen interactions and host defense mechanisms. Here, individual resistant and susceptible plants were selected from cultivars Maverick and ZG9830 and used for transcript profiling at 24 and 72 hours after inoculation (hai) with the isolate PssALF3. Bioinformatic analysis revealed a number of differentially expressed genes (DEGs) in resistant and susceptible genotypes. Although resistant plants from each cultivar produced a hypersensitive response, transcriptome analyses indicated that they respond differently at the molecular level. The number of DEGs was higher in resistant plants of ZG9830 at 24 hai than in Maverick, suggesting that ZG9830 plants had a more rapid effector triggered immune response. Unique up-regulated genes in resistant ZG9830 plants included genes encoding putative nematode resistance HSPRO2-like proteins, orthologs for the rice Xa21 and soybean Rpg1-b resistance genes, and TIR-containing R genes lacking both NBS and LRR domains. The suite of R genes up-regulated in resistant Maverick plants had an over-representation of R genes in the CC-NBS-LRR family including two genes for atypical CCR domains and a putative ortholog of the Arabidopsis RPM1 gene. Resistance in both cultivars appears to be mediated primarily by WRKY family transcription factors and expression of genes involved in protein phosphorylation, regulation of transcription, defense response including synthesis of isoflavonoids, and oxidation-reduction processes. These results will further the identification of mechanisms involved in resistance to facilitate selection of parent populations and development of commercial varieties.

  19. Resistant and susceptible responses in alfalfa (Medicago sativa to bacterial stem blight caused by Pseudomonas syringae pv. syringae.

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    Lev G Nemchinov

    Full Text Available Bacterial stem blight caused by Pseudomonas syringae pv. syringae is a common disease of alfalfa (Medicago sativa L. Little is known about host-pathogen interactions and host defense mechanisms. Here, individual resistant and susceptible plants were selected from cultivars Maverick and ZG9830 and used for transcript profiling at 24 and 72 hours after inoculation (hai with the isolate PssALF3. Bioinformatic analysis revealed a number of differentially expressed genes (DEGs in resistant and susceptible genotypes. Although resistant plants from each cultivar produced a hypersensitive response, transcriptome analyses indicated that they respond differently at the molecular level. The number of DEGs was higher in resistant plants of ZG9830 at 24 hai than in Maverick, suggesting that ZG9830 plants had a more rapid effector triggered immune response. Unique up-regulated genes in resistant ZG9830 plants included genes encoding putative nematode resistance HSPRO2-like proteins, orthologs for the rice Xa21 and soybean Rpg1-b resistance genes, and TIR-containing R genes lacking both NBS and LRR domains. The suite of R genes up-regulated in resistant Maverick plants had an over-representation of R genes in the CC-NBS-LRR family including two genes for atypical CCR domains and a putative ortholog of the Arabidopsis RPM1 gene. Resistance in both cultivars appears to be mediated primarily by WRKY family transcription factors and expression of genes involved in protein phosphorylation, regulation of transcription, defense response including synthesis of isoflavonoids, and oxidation-reduction processes. These results will further the identification of mechanisms involved in resistance to facilitate selection of parent populations and development of commercial varieties.

  20. Antimicrobial susceptibility and clarithromycin resistance patterns of Helicobacter pylori clinical isolates in Vietnam [version 1; referees: 2 approved

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    Camelia Quek

    2016-04-01

    Full Text Available Helicobacter pylori is a gastric pathogen that causes several gastroduodenal disorders such as peptic ulcer disease and gastric cancer.  Eradication efforts of H. pylori are often hampered by antimicrobial resistance in many countries, including Vietnam.  Here, the study aimed to investigate the occurrence of antimicrobial resistance among H. pylori clinical isolates across 13 hospitals in Vietnam.  The study further evaluated the clarithromycin resistance patterns of H. pylori strains.  In order to address the study interests, antimicrobial susceptibility testing, epsilometer test and PCR-based sequencing were performed on a total of 193 strains isolated from patients, including 136 children (3–15 years of age and 57 adults (19–69 years of age.  Antimicrobial susceptibility testing showed that the overall resistance to amoxicillin, clarithromycin, levofloxacin, metronidazole, and tetracycline was 10.4%, 85.5%, 24.4%, 37.8%, and 23.8% respectively.  The distribution of minimum inhibitory concentrations (MICs of clarithromycin-resistant strains was 85.5% with MIC >0.5 μg/mL.  The majority of the clarithromycin resistant isolates (135 of 165 subjects have MICs ranging from 2 μg/mL to 16 μg/mL.  Furthermore, sequencing detection of mutations in 23S rRNA gene revealed that strains resistant and susceptible to clarithromycin contained both A2143G and T2182C mutations.  Of all isolates, eight clarithromycin-resistant isolates (MIC >0.5 μg/mL had no mutations in the 23S rRNA gene.  Collectively, these results demonstrated that a proportion of clarithromycin-resistant H. pylori strains, which are not related to the 23S rRNA gene mutations, could be potentially related to other mechanisms such as the presence of an efflux pump or polymorphisms in the CYP2C19 gene.  Therefore, the present study suggests that providing susceptibility testing prior to treatment or alternative screening strategies for antimicrobial resistance is important

  1. Effect of rapid quenching on the magnetic state, electrical resistivity and thermomagnetic properties of Gd{sub 3}Co

    Energy Technology Data Exchange (ETDEWEB)

    Shishkin, D.A., E-mail: shishkin@imp.uran.ru [Institute of Metal Physics, Russian Academy of Sciences, 620137 Ekaterinburg (Russian Federation); Institute of Natural Sciences, Ural Federal University, 620083 Ekaterinburg (Russian Federation); Proshkin, A.V. [Institute of Metal Physics, Russian Academy of Sciences, 620137 Ekaterinburg (Russian Federation); Selezneva, N.V. [Institute of Natural Sciences, Ural Federal University, 620083 Ekaterinburg (Russian Federation); Gerasimov, E.G.; Terentev, P.B. [Institute of Metal Physics, Russian Academy of Sciences, 620137 Ekaterinburg (Russian Federation); Chirkova, A.M. [IFW Dresden, PO Box 270118, 01171 Dresden (Germany); Institute of Metal Physics, Russian Academy of Sciences, 620137 Ekaterinburg (Russian Federation); Institute of Natural Sciences, Ural Federal University, 620083 Ekaterinburg (Russian Federation); Nenkov, K.; Schultz, L. [IFW Dresden, PO Box 270118, 01171 Dresden (Germany); Baranov, N.V. [Institute of Metal Physics, Russian Academy of Sciences, 620137 Ekaterinburg (Russian Federation); Institute of Natural Sciences, Ural Federal University, 620083 Ekaterinburg (Russian Federation)

    2015-10-25

    The ac-susceptibility, magnetization, electrical resistivity and specific heat measurements have been performed to study the changes in the magnetic state and physical properties of the antiferromagnetic Gd{sub 3}Co compound after rapid quenching from the liquid melt. It has been observed that the amorphization of Gd{sub 3}Co modifies the magnetic state from antiferromagnetic to a soft-ferromagnetic like behavior, increases the magnetic ordering temperature (by about 30%) and leads to substantial changes in the specific heat and electrical resistivity. A considerable enhancement of the exchange interactions in the rapidly solidified Gd{sub 3}Co is ascribed to the appearance of a magnetic moment on Co atoms up to 1.6 μ{sub B}. - Highlights: • The compound Gd{sub 3}Co has been amorphized by the melt-spinning technique. • Amorphization of Gd{sub 3}Co increases the magnetic ordering temperature by 30%. • Gd{sub 3}Co is supposed to exhibit a ferrimagnetic order after amorphization. • A magnetic moment on Co atoms is suggested to appear after amorphization of Gd{sub 3}Co. • Amorphization substantially modifies the resistivity and specific heat of Gd{sub 3}Co.

  2. Transcriptomics and systems biology analysis in identification of specific pathways involved in cacao resistance and susceptibility to witches' broom disease.

    Science.gov (United States)

    da Hora Junior, Braz Tavares; Poloni, Joice de Faria; Lopes, Maíza Alves; Dias, Cristiano Villela; Gramacho, Karina Peres; Schuster, Ivan; Sabau, Xavier; Cascardo, Júlio Cézar De Mattos; Mauro, Sônia Marli Zingaretti Di; Gesteira, Abelmon da Silva; Bonatto, Diego; Micheli, Fabienne

    2012-04-01

    This study reports on expression analysis associated with molecular systems biology of cacao-Moniliophthora perniciosa interaction. Gene expression data were obtained for two cacao genotypes (TSH1188, resistant; Catongo, susceptible) challenged or not with the fungus M. perniciosa and collected at three time points through disease. Using expression analysis, we identified 154 and 227 genes that are differentially expressed in TSH1188 and Catongo, respectively. The expression of some of these genes was confirmed by RT-qPCR. Physical protein-protein interaction (PPPI) networks of Arabidopsis thaliana orthologous proteins corresponding to resistant and susceptible interactions were obtained followed by cluster and gene ontology analyses. The integrated analysis of gene expression and systems biology allowed designing a general scheme of major mechanisms associated with witches' broom disease resistance/susceptibility. In this sense, the TSH1188 cultivar shows strong production of ROS and elicitors at the beginning of the interaction with M. perniciosa followed by resistance signal propagation and ROS detoxification. On the other hand, the Catongo genotype displays defense mechanisms that include the synthesis of some defense molecules but without success in regards to elimination of the fungus. This phase is followed by the activation of protein metabolism which is achieved with the production of proteasome associated with autophagy as a precursor mechanism of PCD. This work also identifies candidate genes for further functional studies and for genetic mapping and marker assisted selection.

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

    Directory of Open Access Journals (Sweden)

    SAM Stephenson

    2016-01-01

    Full Text Available Introduction: Uropathogenic Escherichia coli (UPEC rely on the correlation of virulence expression with antimicrobial resistance to persist and cause severe urinary tract infections (UTIs. Objectives: We assessed the virulence pattern and prevalence among UPEC strains susceptible and resistant to multiple antimicrobial classes. Methods: 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. Results: 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. Conclusions: 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.

  4. Differential lectin labelling of circulating hemocytes from Biomphalaria glabrata and Biomphalaria tenagophila resistant or susceptible to Schistosoma mansoni infection

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    RL Martins-Souza

    2006-10-01

    Full Text Available Lectins/carbohydrate binding can be involved in the Schistosoma mansoni recognition and activation of the Biomphalaria hemocytes. Therefore, expression of lectin ligands on Biomphalaria hemocytes would be associated with snail resistance against S. mansoni infection. To test this hypothesis, circulating hemocytes were isolated from B. glabrata BH (snail strain highy susceptible to S. mansoni, B. tenagophila Cabo Frio (moderate susceptibility, and B. tenagophila Taim (completely resistant strains, labelled with FITC conjugated lectins (ConA, PNA, SBA, and WGA and analyzed under fluorescence microscopy. The results demonstrated that although lectin-labelled hemocytes were detected in hemolymph of all snail species tested, circulating hemocytes from both strains of B. tenagophila showed a larger number of lectin-labelled cells than B. glabrata. Moreover, most of circulating hemocytes of B. tenagophila were intensively labelled by lectins PNA-FITC and WGA-FITC, while in B. glabrata small hemocytes were labeled mainly by ConA. Upon S. mansoni infection, lectin-labelled hemocytes almost disappeared from the hemolymph of Taim and accumulated in B. glabrata BH. The role of lectins/carbohydrate binding in resistance of B. tengophila infection to S. mansoni is still not fully understood, but the data suggest that there may be a correlation to its presence with susceptibility or resistance to the parasite.

  5. Carbapenem-resistant and cephalosporin-susceptible: a worrisome phenotype among Pseudomonas aeruginosa clinical isolates in Brazil

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    Eloiza Helena Campana

    2017-01-01

    Full Text Available The mechanisms involved in the uncommon resistance phenotype, carbapenem resistance and broad-spectrum cephalosporin susceptibility, were investigated in 25 Pseudomonas aeruginosa clinical isolates that exhibited this phenotype, which were recovered from three different hospitals located in São Paulo, Brazil. The antimicrobial susceptibility profile was determined by CLSI broth microdilution. β-lactamase-encoding genes were investigated by PCR followed by DNA sequencing. Carbapenem hydrolysis activity was investigated by spectrophotometer and MALDI-TOF assays. The mRNA transcription level of oprD was assessed by qRT-PCR and the outer membrane proteins profile was evaluated by SDS-PAGE. Genetic relationship among P. aeruginosa isolates was assessed by PFGE. Carbapenems hydrolysis was not detected by carbapenemase assay in the carbapenem-resistant and cephalosporin-susceptible P. aueruginosa clinical isolates. OprD decreased expression was observed in all P. aeruginosa isolates by qRT-PCR. The outer membrane protein profile by SDS-PAGE suggested a change in the expression of the 46 kDa porin that could correspond to OprD porin. The isolates were clustered into 17 genotypes without predominance of a specific PFGE pattern. These results emphasize the involvement of multiple chromosomal mechanisms in carbapenem-resistance among clinical isolates of P. aeruginosa, alert for adaptation of P. aeruginosa clinical isolates under antimicrobial selective pressure and make aware of the emergence of an uncommon phenotype among P. aeruginosa clinical isolates.

  6. The prevalence of genotypes that determine resistance to macrolides, lincosamides, and streptogramins B compared with spiramycin susceptibility among erythromycin-resistant Staphylococcus epidermidis.

    Science.gov (United States)

    Juda, Marek; Chudzik-Rzad, Beata; Malm, Anna

    2016-03-01

    Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, can be regarded as potential reservoirs of resistance genes for pathogenic strains, e.g., Staphylococcus aureus. The aim of this study was to assess the prevalence of different resistance phenotypes to macrolide, lincosamide, and streptogramins B (MLSB) antibiotics among erythromycin-resistant S. epidermidis, together with the evaluation of genes promoting the following different types of MLSB resistance:ermA, ermB, ermC,msrA, mphC, and linA/A'. Susceptibility to spiramycin was also examined. Among 75 erythromycin-resistantS. epidermidis isolates, the most frequent phenotypes were macrolides and streptogramins B (MSB) and constitutive MLSB (cMLSB). Moreover, all strains with the cMLSB phenotype and the majority of inducible MLSB (iMLSB) isolates were resistant to spiramycin, whereas strains with the MSB phenotype were sensitive to this antibiotic. The D-shape zone of inhibition around the clindamycin disc near the spiramycin disc was found for some spiramycin-resistant strains with the iMLSB phenotype, suggesting an induction of resistance to clindamycin by this 16-membered macrolide. The most frequently isolated gene was ermC, irrespective of the MLSB resistance phenotype, whereas the most often noted gene combination wasermC, mphC, linA/A'. The results obtained showed that the genes responsible for different mechanisms of MLSB resistance in S. epidermidis generally coexist, often without the phenotypic expression of each of them.

  7. A rapid virus-induced gene silencing (VIGS) method for assessing resistance and susceptibility to cassava mosaic disease.

    Science.gov (United States)

    Beyene, Getu; Chauhan, Raj Deepika; Taylor, Nigel J

    2017-03-07

    Cassava mosaic disease (CMD) is a major constraint to cassava production in sub-Saharan Africa. Under field conditions, evaluation for resistance to CMD takes 12-18 months, often conducted across multiple years and locations under pressure from whitefly-mediated transmission. Under greenhouse or laboratory settings, evaluation for resistance or susceptibility to CMD involves transmission of the causal viruses from an infected source to healthy plants through grafting, or by using Agrobacterium-mediated or biolistic delivery of infectious clones. Following inoculation, visual assessment for CMD symptom development and recovery requires 12-22 weeks. Here we report a rapid screening system for determining resistance and susceptibility to CMD based on virus-induced gene silencing (VIGS) of an endogenous cassava gene. A VIGS vector was developed based on an infectious clone of the virulent strain of East African cassava mosaic virus (EACMV-K201). A sequence from the cassava (Manihot esculenta) ortholog of Arabidopsis SPINDLY (SPY) was cloned into the CP position of the DNA-A genomic component and used to inoculate cassava plants by Helios® Gene Gun microparticle bombardment. Silencing of Manihot esculenta SPY (MeSPY) using MeSPY1-VIGS resulted in shoot-tip necrosis followed by death of the whole plant in CMD susceptible cassava plants within 2-4 weeks. CMD resistant cultivars were not affected and remained healthy after challenge with MeSPY1-VIGS. Significantly higher virus titers were detected in CMD-susceptible cassava lines compared to resistant controls and were correlated with a concomitant reduction in MeSPY expression in susceptible plants. A rapid VIGS-based screening system was developed for assessing resistance and susceptibility to CMD. The method is space and resource efficient, reducing the time required to perform CMD screening to as little as 2-4 weeks. It can be employed as a high throughput rapid screening system to assess new cassava cultivars and for

  8. A rapid in situ procedure for determination of bacterial susceptibility or resistance to antibiotics that inhibit peptidoglycan biosynthesis

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    Bou Germán

    2011-08-01

    Full Text Available Abstract Background Antibiotics which inhibit bacterial peptidoglycan biosynthesis are the most widely used in current clinical practice. Nevertheless, resistant strains increase dramatically, with serious economic impact and effects on public health, and are responsible for thousands of deaths each year. Critical clinical situations should benefit from a rapid procedure to evaluate the sensitivity or resistance to antibiotics that act at the cell wall. We have adapted a kit for rapid determination of bacterial DNA fragmentation, to assess cell wall integrity. Results Cells incubated with the antibiotic were embedded in an agarose microgel on a slide, incubated in an adapted lysis buffer, stained with a DNA fluorochrome, SYBR Gold and observed under fluorescence microscopy. The lysis affects the cells differentially, depending on the integrity of the wall. If the bacterium is susceptible to the antibiotic, the weakened cell wall is affected by the lysing solution so the nucleoid of DNA contained inside the bacterium is released and spread. Alternatively, if the bacterium is resistant to the antibiotic, it is practically unaffected by the lysis solution and does not liberate the nucleoid, retaining its normal morphological appearance. In an initial approach, the procedure accurately discriminates susceptible, intermediate and resistant strains of Escherichia coli to amoxicillin/clavulanic acid. When the bacteria came from an exponentially growing liquid culture, the effect on the cell wall of the β-lactam was evident much earlier that when they came from an agar plate. A dose-response experiment with an E. coli strain susceptible to ampicillin demonstrated a weak effect before the MIC dose. The cell wall damage was not homogenous among the different cells, but the level of damage increased as dose increased with a predominant degree of effect for each dose. A microgranular-fibrilar extracellular background was evident in gram

  9. In vitro activity of tigecycline and comparators against carbapenem-susceptible and resistant Acinetobacter baumannii clinical isolates in Italy

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    Carattoli Alessandra

    2008-02-01

    Full Text Available Abstract Background In a recent multi-centre Italian survey (2003–2004, conducted in 45 laboratories throughout Italy with the aim of monitoring microorganisms responsible for severe infections and their antibiotic resistance, Acinetobacter baumannii was isolated from various wards of 9 hospitals as one of the most frequent pathogens. One hundred and seven clinically significant strains of A. baumannii isolates were included in this study to determine the in vitro activity of tigecycline and comparator agents. Methods Tests for the susceptibility to antibiotics were performed by the broth microdilution method as recommended by CLSI guidelines. The following antibiotics were tested: aztreonam, piperacillin/tazobactam, ampicillin/sulbactam, ceftazidime, cefepime, imipenem, meropenem tetracycline, doxycycline, tigecycline, gentamicin, amikacin, ciprofloxacin, colistin, and trimethoprim/sulphametoxazole. The PCR assay was used to determine the presence of OXA, VIM, or IMP genes in the carbapenem resistant strains. Results A. baumannii showed widespread resistance to ceftazidime, ciprofloxacin and aztreonam in more than 90% of the strains; resistance to imipenem and meropenem was 50 and 59% respectively, amikacin and gentamicin were both active against about 30% of the strains and colistin about 99%, with only one strain resistant. By comparison with tetracyclines, tigecycline and doxycycline showed a higher activity. In particular, tigecycline showed a MIC90 value of 2 mg/L and our strains displayed a unimodal distribution of susceptibility being indistinctly active against carbapenem-susceptible and resistant strains, these latter possessed OXA-type variant enzymes. Conclusion In conclusion, tigecycline had a good activity against the MDR A. baumannii strains while maintaining the same MIC90 of 2 mg/L against the carbapenem-resistant strains.

  10. Comparative Transcriptome Analysis of Resistant and Susceptible Common Bean Genotypes in Response to Soybean Cyst Nematode Infection.

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    Shalu Jain

    Full Text Available Soybean cyst nematode (SCN; Heterodera glycines Ichinohe reproduces on the roots of common bean (Phaseolus vulgaris L. and can cause reductions in plant growth and seed yield. The molecular changes in common bean roots caused by SCN infection are unknown. Identification of genetic factors associated with SCN resistance could help in development of improved bean varieties with high SCN resistance. Gene expression profiling was conducted on common bean roots infected by SCN HG type 0 using next generation RNA sequencing technology. Two pinto bean genotypes, PI533561 and GTS-900, resistant and susceptible to SCN infection, respectively, were used as RNA sources eight days post inoculation. Total reads generated ranged between ~ 3.2 and 5.7 million per library and were mapped to the common bean reference genome. Approximately 70-90% of filtered RNA-seq reads uniquely mapped to the reference genome. In the inoculated roots of resistant genotype PI533561, a total of 353 genes were differentially expressed with 154 up-regulated genes and 199 down-regulated genes when compared to the transcriptome of non- inoculated roots. On the other hand, 990 genes were differentially expressed in SCN-inoculated roots of susceptible genotype GTS-900 with 406 up-regulated and 584 down-regulated genes when compared to non-inoculated roots. Genes encoding nucleotide-binding site leucine-rich repeat resistance (NLR proteins, WRKY transcription factors, pathogenesis-related (PR proteins and heat shock proteins involved in diverse biological processes were differentially expressed in both resistant and susceptible genotypes. Overall, suppression of the photosystem was observed in both the responses. Furthermore, RNA-seq results were validated through quantitative real time PCR. This is the first report describing genes/transcripts involved in SCN-common bean interaction and the results will have important implications for further characterization of SCN resistance genes in

  11. Comparative Transcriptome Analysis of Resistant and Susceptible Common Bean Genotypes in Response to Soybean Cyst Nematode Infection.

    Science.gov (United States)

    Jain, Shalu; Chittem, Kishore; Brueggeman, Robert; Osorno, Juan M; Richards, Jonathan; Nelson, Berlin D

    2016-01-01

    Soybean cyst nematode (SCN; Heterodera glycines Ichinohe) reproduces on the roots of common bean (Phaseolus vulgaris L.) and can cause reductions in plant growth and seed yield. The molecular changes in common bean roots caused by SCN infection are unknown. Identification of genetic factors associated with SCN resistance could help in development of improved bean varieties with high SCN resistance. Gene expression profiling was conducted on common bean roots infected by SCN HG type 0 using next generation RNA sequencing technology. Two pinto bean genotypes, PI533561 and GTS-900, resistant and susceptible to SCN infection, respectively, were used as RNA sources eight days post inoculation. Total reads generated ranged between ~ 3.2 and 5.7 million per library and were mapped to the common bean reference genome. Approximately 70-90% of filtered RNA-seq reads uniquely mapped to the reference genome. In the inoculated roots of resistant genotype PI533561, a total of 353 genes were differentially expressed with 154 up-regulated genes and 199 down-regulated genes when compared to the transcriptome of non- inoculated roots. On the other hand, 990 genes were differentially expressed in SCN-inoculated roots of susceptible genotype GTS-900 with 406 up-regulated and 584 down-regulated genes when compared to non-inoculated roots. Genes encoding nucleotide-binding site leucine-rich repeat resistance (NLR) proteins, WRKY transcription factors, pathogenesis-related (PR) proteins and heat shock proteins involved in diverse biological processes were differentially expressed in both resistant and susceptible genotypes. Overall, suppression of the photosystem was observed in both the responses. Furthermore, RNA-seq results were validated through quantitative real time PCR. This is the first report describing genes/transcripts involved in SCN-common bean interaction and the results will have important implications for further characterization of SCN resistance genes in common bean.

  12. Sumac (Rhus coriaria L. Represents a Considerable Antibacterial Activity Against Meticillin Susceptible and Meticillin Resistant Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Mohammad Mahdi Ahmadian-Attari

    2017-08-01

    Full Text Available Background: Staphylococcus aureus is one of the most important pathogens and the cause of suppuration, abscess formation, a variety of pyogenic infections, and even fatal septicemia in human beings. Isolation of resistant strains of S. aureus especially meticillin-resistant one has elucidated the importance of finding new antibacterial agents. Sumac is one of the important medicinal herbs of Iranian traditional medicine (ITM. Sumac has been traditionally prescribed for some ailments with infectious etiology and therefore, it probably contains antibacterial compounds. Recently, antibacterial activities of sumac against some bacteria were studied by our team. Objective: In this article, we aimed to compare the antibacterial activities of sumac against meticillin susceptible (MSSA and meticillin resistant S. aureus (MRSA via minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC determination. Materials and Methods: Antibacterial activity of sumac water extract was studied on 19 clinical and 1 standard strain of S. aureus via MIC and MBC determination. Based on their sensitivity to cloxacillin, these bacteria were classified as meticillin-susceptible, intermediate meticillin-resistant, and meticillin-resistant. MICs and MBCs of the extracts in these 3 groups were statistically compared via one-way analysis of variance (ANOVA followed by a post hoc analysis (Tukey HSD test using SPSS for Windows (version 15. Results: The results showed that in spite of different susceptibilities to cloxacillin, susceptibility to sumac extract was not different and MICs and MBCs of sumac for all clinical isolates including MSSA and MRSA were similar (P > 0.05. Conclusion: Based on previous studies, sumac extract acts against S. aureus probably through changing the cell wall properties. This activity is similar for both MRSA and MSSA. More investigation on the precise mechanism of action of this extract would be fruitful.

  13. A toxin-binding alkaline phosphatase fragment synergizes Bt toxin Cry1Ac against susceptible and resistant Helicoverpa armigera.

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    Wenbo Chen

    Full Text Available Evolution of resistance by insects threatens the continued success of pest control using insecticidal crystal (Cry proteins from the bacterium Bacillus thuringiensis (Bt in sprays and transgenic plants. In this study, laboratory selection with Cry1Ac yielded five strains of cotton bollworm, Helicoverpa armigera, with resistance ratios at the median lethal concentration (LC50 of activated Cry1Ac ranging from 22 to 1700. Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains. A Cry1Ac-binding fragment of alkaline phosphatase from H. armigera (HaALP1f was not toxic by itself, but it increased mortality caused by Cry1Ac in a susceptible strain and in all five resistant strains. Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase. The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

  14. An Ultra-Precise System for Electrical Resistivity Tomography Measurements

    Energy Technology Data Exchange (ETDEWEB)

    LaBrecque, Douglas J; Adkins, Paula L

    2008-12-09

    The objective of this research was to determine the feasibility of building and operating an ERT system that will allow measurement precision that is an order of magnitude better than existing systems on the market today and in particular if this can be done without significantly greater manufacturing or operating costs than existing commercial systems. Under this proposal, we performed an estimation of measurement errors in galvanic resistivity data that arise as a consequence of the type of electrode material used to make the measurements. In our laboratory, measurement errors for both magnitude and induced polarization (IP) were estimated using the reciprocity of data from an array of electrodes as might be used for electrical resistance tomography using 14 different metals as well as one non-metal - carbon. In a second phase of this study, using archival data from two long-term ERT surveys, we examined long-term survivability of electrodes over periods of several years. The survey sites were: the Drift Scale Test at Yucca Mountain, Nevada (which was sponsored by the U. S. Department of Energy as part of the civilian radioactive waste management program), and a water infiltration test at a site adjacent to the New Mexico Institute of Mines and Technology in Socorro, New Mexico (sponsored by the Sandia/Tech vadose program). This enabled us to compare recent values with historical values and determine electrode performance over the long-term as well as the percentage of electrodes that have failed entirely. We have constructed a prototype receiver system, made modifications and revised the receiver design. The revised prototype uses a new 24 bit analog to digital converter from Linear Technologies with amplifier chips from Texas Instruments. The input impedance of the system will be increased from 107 Ohms to approximately 1010 Ohms. The input noise level of the system has been decreased to approximately 10 Nanovolts and system resolution to about 1 Nanovolt at

  15. Identification of candidate susceptibility and resistance genes of mice infected with Streptococcus suis type 2.

    Directory of Open Access Journals (Sweden)

    Jie Rong

    infection. This study identified candidate genes that may influence susceptibility or resistance to SS2 infection in A/J and B6 mice, providing further validation of these models and contributing to understanding of S. suis pathogenic mechanisms.

  16. Using DC electrical resistivity tomography to quantify preferential flow in fractured rock environments

    CSIR Research Space (South Africa)

    May, F

    2011-09-01

    Full Text Available . This investigation aims to identify preferential flow paths in fractured rock environments. Time-lapse Electrical Resistivity Tomography (TLERT, Lund Imaging System), is regarded as a suitable method for identifying preferential water flow....

  17. Wireless Damage Monitoring of Laminated CFRP Composites using Electrical Resistance Change

    National Research Council Canada - National Science Library

    Todoroki, Akira

    2007-01-01

    .... In this system, a tiny oscillation circuit is attached to the composite component. When delimitation of the component occurs, electrical resistance changes, which causes a change in the oscillating frequency of the circuit...

  18. Application of column tests and electrical resistivity methods for leachate transport monitoring

    National Research Council Canada - National Science Library

    Dorota Wychowaniak; Łukasz Zawadzki; Mariusz Lech

    2015-01-01

    ... out. Furthermore, the electrical resistivity method was applied as auxiliary tool to follow the movements of solute through the soil column what allowed to compare between the results obtained with column...

  19. Second line drug susceptibility testing to inform the treatment of rifampin-resistant tuberculosis: a quantitative perspective

    Directory of Open Access Journals (Sweden)

    Emily A. Kendall

    2017-03-01

    Full Text Available Treatment failure and resistance amplification are common among patients with rifampin-resistant tuberculosis (TB. Drug susceptibility testing (DST for second-line drugs is recommended for these patients, but logistical difficulties have impeded widespread implementation of second-line DST in many settings. To provide a quantitative perspective on the decision to scale up second-line DST, we synthesize literature on the prevalence of second-line drug resistance, the expected clinical and epidemiologic benefits of using second-line DST to ensure that patients with rifampin-resistant TB receive effective regimens, and the costs of implementing (or not implementing second-line DST for all individuals diagnosed with rifampin-resistant TB. We conclude that, in most settings, second-line DST could substantially improve treatment outcomes for patients with rifampin-resistant TB, reduce transmission of drug-resistant TB, prevent amplification of drug resistance, and be affordable or even cost-saving. Given the large investment made in each patient treated for rifampin-resistant TB, these payoffs would come at relatively small incremental cost. These anticipated benefits likely justify addressing the real challenges faced in implementing second-line DST in most high-burden settings.

  20. Insecticide susceptible/resistance status in Aedes (Stegomyia) aegypti and Aedes (Stegomyia) albopictus (Diptera: Culicidae) in Thailand during 2003-2005.

    Science.gov (United States)

    Jirakanjanakit, Nuananong; Rongnoparut, Pornpimol; Saengtharatip, Seeviga; Chareonviriyaphap, Theeraphap; Duchon, Stephane; Bellec, Christian; Yoksan, Sutee

    2007-04-01

    Susceptibility baselines and diagnostic doses of the technical grade insecticides deltamethrin, permethrin, fenitrothion, and propoxur were established based on Aedes aegypti (L.), Bora (French Polynesia), a reference susceptible strain. Field-collected Aedes mosquitoes from each part of Thailand were subjected to bioassay for their susceptibility to the diagnostic doses of each insecticide. Almost all Ae. aegypti collected were incipient resistant or resistant to deltamethrin and permethrin, except those from some areas of Songkhla (southern) and Phan district of Chiang Rai (northern) province. Susceptibility to fenitrothion was found in mosquitoes from Bangkok (central), Chonburi (eastern), Chiang Rai, Kanchanaburi (western), and Songkhla, whereas they were resistant in almost all areas of Nakhon Sawan (north central) and Nakhon Ratchasima (northeastern) provinces. Most of Ae. aegypti were susceptible to propoxur except those from Mae Wong, Nakhon Sawan province. Various levels of insecticide resistance and susceptibility in adjacent areas revealed a focal susceptible/resistance profile in the country. It could be noted that almost all of Ae. albopictus were susceptible to the insecticides tested at the same diagnostic doses. In conclusion, resistance to pyrethroids (permethrin and deltamethrin) has developed in Ae. aegypti in most of the collected areas, suggesting that an alternative choice of insecticide or other control measures should be applied.

  1. Antimicrobial susceptibilities of Proteus mirabilis: a longitudinal nationwide study from the Taiwan surveillance of antimicrobial resistance (TSAR) program.

    Science.gov (United States)

    Wang, Jann-Tay; Chen, Pei-Chen; Chang, Shan-Chwen; Shiau, Yih-Ru; Wang, Hui-Ying; Lai, Jui-Fen; Huang, I-Wen; Tan, Mei-Chen; Lauderdale, Tsai-Ling Yang

    2014-09-05

    Longitudinal nationwide data on antimicrobial susceptibility in Proteus mirabilis from different sources are rare. The effects of the revised Clinical and Laboratory Standards Institute (CLSI) β-lactam breakpoints on susceptibility rates and on detecting extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase-producers in this species are also seldom evaluated. The present study analyzed data from the Taiwan Surveillance of Antimicrobial Resistance program to address these issues. Isolates were collected biennially between 2002 and 2012 from 25 to 28 hospitals in Taiwan. Minimum inhibitory concentrations (MIC) were determined by reference broth microdilution method. All isolates with aztreonam, ceftazidime, or cefotaxime MIC ≥ 2 mg/L were checked for the presence of ESBL by CLSI confirmatory test and subjected to ESBL and AmpC β-lactamases gene detection by PCR. Univariate and multivariate analyses were performed. Between 2002 and 2012, a total of 1157 P. mirabilis were studied. Susceptibility to cefotaxime, ceftazidime, and ciprofloxacin decreased significantly during the past decade, from 92.6% to 81.7%, 100% to 95.2%, and 80.1% to 53.8%, respectively (P < 0.01). The revised CLSI breakpoints had significant impact on susceptibility to cefazolin (2009 vs. current breakpoints, 71.9% vs. 0.9%) and imipenem (99.8% vs. 55.1%) (P < 0.001 for both). However, using the 2014 cefazolin breakpoints for urinary tract infections, 81.2% of the urine isolates were susceptible. Susceptibilities of isolates from different specimen types were mostly similar but outpatient isolates were more susceptible than inpatient isolates. The overall prevalence of ESBL- and AmpC- producers was 8.2% and 4.7%, respectively, but AmpC carriage increased significantly over the years (from 0 to 7.0%, P < 0.001). ESBL and AmpC β-lactamase-producers were more likely to be found in elderly and ICU patients. The predominant ESBL and AmpC β-lactamase genes were CTX-M- and CMY

  2. Correspondence between electrical resistivity and total suction in compacted kaolin considering the presence of salt

    Directory of Open Access Journals (Sweden)

    Dias Ana Sofia

    2016-01-01

    Full Text Available Prospection techniques based on measuring the electrical resistivity of geomaterials are being used mainly for geophysical characterization, for evaluating soil contamination and the extension of contaminated areas, in addition to the compaction control in geotechnical works. This technique is based on the fact that contrasts in electrical resistivity along the profiles analysed help identifying zones of transition, because this property is affected by the presence of water and dissolved salts in the electrolyte, as well as by soil structure. However, in situ data interpretation has some difficulties because electrical resistivity is affected by changes in the unsaturated state of the soil, as well as by the presence of salt compounds (natural or from contamination. The correspondence between electrical resistivity and total suction in compacted kaolin considering the presence of salt was investigated in the study presented. The samples tested were compacted for the same voids ratio and water content, however one type was prepared with distilled water and the other with a NaCl solution (0.5 M. This is a relatively small concentration of salt, to which there were no significant changes in the liquid and plasticity limits, neither on zeta potential if pH is equal to 7, however the quantity of ions supplied was enough to affect the electrical resistivity of the compacted material. The water retention curve of the two kinds of samples was determined using a water dewpoint device and through vapour equilibrium. The electrical resistivity was measured in samples to which suction was known, allowing to find a relationship between total suction and electrical conductivity, and therefore between water content and electrical resistivity. The results found are commented considering the electrical transport through the liquid phase and its continuity in the porous media, which depends on the conductivity of the electrolyte and on the degree of saturation.

  3. Characterisation of electrical resistance for CMC Materials up to 1200 °C

    Science.gov (United States)

    Stäbler, T.; Böhrk, H.; Voggenreiter, H.

    2017-12-01

    Damage to thermal protection systems (TPS) during atmospheric re-entry is a severe safety issue, especially when considering re-usability of space transportation systems. There is a need for structural health monitoring systems and non-destructive inspection methods. However, damages are hard to detect. When ceramic matrix composites, in this case carbon fibre reinforced silicon carbide (C/C-SiC), are used as a TPS, the electrical properties of the present semiconductor material can be used for health monitoring, since the resistivity changes with damage, strain and temperature. In this work the electrical resistivity as a function of the material temperature is analysed eliminating effects of thermal electricity and the thermal coefficient of electrical resistance is determined. A sensor network is applied for locally and time resolved monitoring of the 300 mm x 120 mm x 3 mm panel shaped samples. Since the material is used for atmospheric re-entry it needs to be characterised for a wide range of temperatures, in this case as high as 1200 °C. Therefore, experiments in an inductively heated test bench were conducted. Firstly, a reference sample was used with thermocouples for characterising the temperature distribution across the sample surface. Secondly, electrical resistance under heat load was measured, time and spatially resolved. Results will be shown and discussed in terms of resistance dependence on temperature, thermal coefficient of electrical resistance, thermal electricity and electrical path orientation including an analysis on effective conducting cross section. Conversely, the thermal coefficient can also be used to determine the material temperature as a function of electrical resistance.

  4. Using different ELECTRE methods in strategic planning in the presence of human behavioral resistance

    Directory of Open Access Journals (Sweden)

    A. S. Milani

    2006-01-01

    Full Text Available In the multicriteria strategic planning of an organization, management should often be aware of employees' resistance to change before making new decisions; otherwise, a chosen strategy, though technologically acceptable, may not be efficient in the long term. This paper, using a sample case study within an organization, shows how different versions of ELECTRE methods can be used in choosing efficient strategies that account for both human behavioral resistance and technical elements. The effect of resistance from each subsystem of the organization is studied to ensure the reliability of the chosen strategy. The comparison of results from a select number of compensatory and noncompensatory models (ELECTRE I, III, IV, IS; TOPSIS; SAW; MaxMin suggests that when employee resistance is a decision factor in the multicriteria strategic planning problem, the models can yield low-resistance strategies; however, ELECTRE seems to show more reasonable sensitivity.

  5. [Susceptibilities of multidrug-resistant pathogens responsible for complicated skin and soft tissue infections to standard bacteriophage cocktails].

    Science.gov (United States)

    Gündoğdu, Aycan; Kılıç, Hüseyin; Ulu Kılıç, Ayşegül; Kutateladze, Mzia

    2016-04-01

    Skin and soft tissue infections (SSTIs) may represent a wide clinical spectrum from cellulitis to high-mortality associated necrotizing fasciitis. Limitations in therapy due to the multiple drug resistance, leads to increase in the morbidity and mortality rates, especially in complicated SSTIs such as diabetic foot, decubitus, and surgical wound infections. Therefore, alternative treatment strategies other than antibiotics are needed in appropriate clinical conditions. "Bacteriophage therapy", which is an old method and has been used as part of standard treatment in some countries such as Georgia and Russia, has again become popular worldwide. The aim of this study was to investigate the in vitro susceptibilities of multidrug-resistant (MDR) pathogens isolated from patients with complicated SSTIs, against standard bacteriophage (phage) cocktails. Six different ready-made phage preparations [Pyophage, Intestiphage, ENKO, SES, Fersisi and Staphylococcal Bacteriophage (Sb)] used in this study have been provided by G. Eliava Institute, Georgia. Because of the absence of ready-made phage preparations for Acinetobacter baumannii and Klebsiella pneumoniae, Φ1-Φ7 and ΦKL1- ΦKL3 phages were used provided from the same institute's phage library, respectively. Isolation and identification of the pathogens from abscess and wound samples of patients with SSTIs were performed by conventional methods and automatized VITEK(®)-2 (bioMerieux, ABD) system. Antimicrobial susceptibility testing was conducted complying CLSI standards' and the bacteria that were resistant to at least two different antibiotic groups were considered as MDR. Accordingly, a total of 33 isolates, nine of them were E.coli (8 ESBL and 1 ESBL + carbapenemase positive); nine were MDR P.aeruginosa; nine were MDR A.baumannii; three were methicillin-resistant Staphylococcus aureus (MRSA) and three were K.pneumoniae (1 ESBL, 1 carbapenemase and 1 ESBL + carbapenemase positive) were included in the study. The

  6. In vitro activity of nitazoxanide against some metronidazole-resistant and susceptible Trichomonas vaginalis isolates.

    Science.gov (United States)

    Abdel-Magied, Aida A; Hammouda, Marwa M; Mosbah, Alaa; El-Henawy, Abeer A

    2017-04-01

    Trichomonas vaginalis cases refractory to metronidazole (MTZ) treatment had been reported. This study aimed to the assessment of in vitro metronidazole resistance among Trichomonas positive cases with treatment failure by determination of metronidazole minimal lethal concentration (MLC), and to the evaluation of the in vitro efficacy of nitazoxanide (NTZ) as compared to metronidazole (MTZ) in both resistant and susceptible isolates. Drug testing was carried out by an aerobic tube assay where suspension of Trichomonas trophozoites was exposed for 24 and 48 h to serial dilution of metronidazole and nitazoxanide. In refractory isolates n = 30, median MLC conc. for MTZ was 100 μg/ml versus 50 μg/ml for NTZ (P < .0001). After 48 h median MLC conc. for MTZ was 25 μg/ml versus 12 μg/ml for NTZ (P < .0001). NTZ against resistant isolates was twice as active as MTZ at 24 h and increased to 2.5 times at 48 h while in susceptible isolates, NTZ was twice as active as MTZ at both 24 h and 48 h. MTZ was about 8 times more active in susceptible than in resistant isolates. So, high doses of metronidazole in resistant cases will likely increase side effects. The study proved the activity of NTZ against trichomoniasis especially in cases with MTZ resistance. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  7. Chlorhexidine and Mupirocin Susceptibility of Methicillin-Resistant Staphylococcus aureus Isolates in the REDUCE-MRSA Trial.

    Science.gov (United States)

    Hayden, Mary K; Lolans, Karen; Haffenreffer, Katherine; Avery, Taliser R; Kleinman, Ken; Li, Haiying; Kaganov, Rebecca E; Lankiewicz, Julie; Moody, Julia; Septimus, Edward; Weinstein, Robert A; Hickok, Jason; Jernigan, John; Perlin, Jonathan B; Platt, Richard; Huang, Susan S

    2016-11-01

    Whether targeted or universal decolonization strategies for the control of methicillin-resistant Staphylococcus aureus (MRSA) select for resistance to decolonizing agents is unresolved. The REDUCE-MRSA trial (ClinicalTrials registration no. NCT00980980) provided an opportunity to investigate this question. REDUCE-MRSA was a 3-arm, cluster-randomized trial of either screening and isolation without decolonization, targeted decolonization with chlorhexidine and mupirocin, or universal decolonization without screening to prevent MRSA infection in intensive-care unit (ICU) patients. Isolates from the baseline and intervention periods were collected and tested for susceptibility to chlorhexidine gluconate (CHG) by microtiter dilution; mupirocin susceptibility was tested by Etest. The presence of the qacA or qacB gene was determined by PCR and DNA sequence analysis. A total of 3,173 isolates were analyzed; 2 were nonsusceptible to CHG (MICs, 8 μg/ml), and 5/814 (0.6%) carried qacA or qacB At baseline, 7.1% of MRSA isolates expressed low-level mupirocin resistance, and 7.5% expressed high-level mupirocin resistance. In a mixed-effects generalized logistic regression model, the odds of mupirocin resistance among clinical MRSA isolates or MRSA isolates acquired in an ICU in intervention versus baseline periods did not differ across arms, although estimates were imprecise due to small numbers. Reduced susceptibility to chlorhexidine and carriage of qacA or qacB were rare among MRSA isolates in the REDUCE-MRSA trial. The odds of mupirocin resistance were no different in the intervention versus baseline periods across arms, but the confidence limits were broad, and the results should be interpreted with caution. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  8. Decreased susceptibility to zinc chloride is associated with methicillin resistant Staphylococcus aureus CC398 in Danish swine

    DEFF Research Database (Denmark)

    Aarestrup, Frank Møller; Cavaco, Lina; Hasman, Henrik

    2010-01-01

    A total of 31 MRSA and 60 MSSA isolated from different swine farms in Denmark were examined for their susceptibility to zinc chloride, erythromycin, penicillin and tetracycline, as well as their spa-type. mecA positive isolates were examined for their SCCmec type. The isolates were assigned to a CC......-type based on their spa-type and supportive multi-locus sequence typing (MLST). No difference in susceptibility to erythromycin, penicillin or tetracycline could be observed between methicillin resistant and susceptible isolates of CC398. Twenty-three (74%) of the MRSA CC398 isolates had reduced...... susceptibility to ZnCl2 (MIC 4-12 mM), whereas all MSSA had MICs from 0.5 to 2 mM. Thirty MRSA, including all 23 zinc resistant isolates harboured SCCmec type V. This provides biological evidence to suggest that the use of zinc compounds may be partly implicated in the emergence of some MRSA clones among swine...

  9. An appraisal of the electrical resistance method for assessing root surface area

    Science.gov (United States)

    Cao, Yang; Repo, Tapani; Silvennoinen, Raimo; Lehto, Tarja; Pelkonen, Paavo

    2010-01-01

    Electrical resistances of roots and stems of hydroponically raised willows (Salix schwerinii) were studied and related to root morphology. Willow cuttings with and without roots were set in a constant electric field (effective voltage of 0.1 V, sine-AC, 128 Hz) in a hydroponic solution. The electrical resistance of different components in the measurement system was measured and analysed in relation to root surface area in contact with the cultivation solution. Axial resistivities of single root segments and of stems were measured. The results showed that the resistance decreased in relation to an increase in the contact surface area of the roots with the solution. The resistance depended strongly on the contact area of the stem with the solution, however, thus causing bias in the evaluation of root surface area. This work is a new contribution for the understanding of current pathways in the root system as exposed to an external electric field and for developing a non-destructive method to study plant roots accordingly. It may be concluded that the electrical resistance method is a useful non-destructive method to study roots and their physiological properties. Electrical analogues for roots and stem comprising resistors are discussed in relation to in situ measurements. PMID:20363862

  10. Detection of quantitative trait loci for resistance/susceptibility to pseudorabies virus in swine.

    Science.gov (United States)

    Reiner, Gerald; Melchinger, Elke; Kramarova, Marcela; Pfaff, Eberhardt; Büttner, Matthias; Saalmüller, Armin; Geldermann, Hermann

    2002-01-01

    This study describes genetic differences in resistance/susceptibility to pseudorabies virus (PrV) between European Large White and Chinese Meishan pigs, with a mapping of quantitative trait loci (QTL) obtained from a genome-wide scan in F(2) animals. Eighty-nine F(2) pigs were challenged intranasally at 12 weeks with 10(5) p.f.u. of the wild-type PrV strain NIA-3. For QTL analysis, 85 microsatellite markers, evenly spaced on the 18 porcine autosomes and on the pseudoautosomal region of the X chromosome, were genotyped. All pigs developed clinical signs, i.e. fever, from 3 to 7 days p.i. The pure-bred Large White pigs, the F(1) and three-quarters of the F(2) animals, but none of the Meishan pigs, developed neurological symptoms and died or were euthanized. QTLs for appearance/non-appearance of neurological symptoms were found on chromosomes 9, 5, 6 and 13. They explained 10.6-17.9% of F(2) phenotypic variance. QTL effects for rectal temperature after PrV challenge were found on chromosomes 2, 4, 8, 10, 11 and 16. Effects on chromosomes 9, 10 and 11 were significant on a genome-wide level. The results present chromosomal regions that are associated with presence/absence of neurological symptoms as well as temperature course after intranasal challenge with NIA-3. The QTLs are in proximity to important candidate genes that are assumed to play crucial roles in host defence against PrV.

  11. Reporting of meticillin-resistant and -susceptible Staphylococcus aureus on death certificates in Irish hospitals.

    LENUS (Irish Health Repository)

    Collins, C J

    2011-02-01

    The documentation of infection with meticillin-resistant Staphylococcus aureus (MRSA) on death certificates has been the subject of considerable public discussion. Using data from five tertiary referral hospitals in Ireland, we compared the documentation of MRSA and meticillin-susceptible S. aureus (MSSA) on death certificates in those patients who died in hospital within 30 days of having MRSA or MSSA isolated from blood cultures. A total of 133 patients had MRSA or MSSA isolated from blood cultures within 30 days of death during the study period. One patient was excluded as the death certificate information was not available; the other 132 patients were eligible for inclusion. MRSA and MSSA were isolated from blood cultures in 59 (44.4%) and 74 (55.6%) cases respectively. One patient was included as a case in both categories as both MRSA and MSSA were isolated from a blood culture. In 15 (25.4%) of the 59 MRSA cases, MRSA was documented on the death certificate. In nine (12.2%) of the 74 patients with MSSA cases, MSSA was documented on the death certificate. MRSA was more likely to be documented on the death certificate than MSSA (odds ratio: 2.46; 95% confidence interval: 1.01-6.01; P < 0.05). These findings indicate that there may be inconsistencies in the way organisms and infections are documented on death certificates in Ireland and that death certification data may underestimate the mortality related to certain organisms. In particular, there appears to be an overemphasis by certifiers on the documentation of MRSA compared with MSSA.

  12. Divergent metabolic adaptations to intestinal parasitic nematode infection in mice susceptible or resistant to obesity.

    Science.gov (United States)

    Wong, Tracie; Hildebrandt, Marie A; Thrasher, Seana M; Appleton, Judith A; Ahima, Rexford S; Wu, Gary D

    2007-12-01

    Diet-induced obesity results from increased ingestion of energy-dense food and sedentary lifestyle in genetically susceptible individuals. An environmental factor that may have shaped our energy homeostasis throughout evolution is parasitic nematode infection. To test the hypothesis that a metabolically "thrifty phenotype" is advantageous during intestinal nematode infection, we compared the responses to Heligmosomoides polygyrus infection between 2 mouse strains: obesity-prone C57Bl/6J vs obesity-resistant SWR/J. Metabolic phenotyping was performed using indirect calorimetry, dual energy x-ray absorptiometry, and magnetic resonance imaging scanning. Gene expression was assessed by quantitative reverse-transcription polymerase chain reaction and immunohistochemistry. Body weight was maintained in both strains during nematode infection via different mechanisms. There was no apparent change in energy expenditure between the strains; however, SWR/J mice exhibited a marked hyperphagia (calorie intake 60% higher than C57Bl/6J) to maintain body weight. The importance of hyperphagia was confirmed by severe weight loss in a group of infected SWR/J mice whose food intake was restricted to that of naïve mice. Furthermore, SWR/J mice expelled nematodes more rapidly than C57Bl/6J mice, an effect related to a T helper cell 2 immune response. C57Bl/6J mice are more energy efficient during parasitic nematode infection, which may explain their ability to tolerate the infection. SWR/J mice, on the other hand, require an increase in food intake to maintain energy stores during nematode infection. In addition, a strong T helper cell 2-mediated immune response that facilitates a prompt clearance of nematode infection in SWR/J mice may have evolved to conserve energy in this strain.

  13. Visceral leishmaniasis in congenic mice of susceptible and resistant phenotypes: immunosuppression by adherent spleen cells.

    Science.gov (United States)

    Nickol, A D; Bonventre, P F

    1985-10-01

    Visceral leishmaniasis is one of several parasitic diseases of humans characterized by immune suppression. A murine model of disseminated leishmaniasis utilizing inbred strains of specific genetic constitution was used to study the mechanisms of immunosuppression elicited during the course of infection. Resistant (Lshr) and susceptible (Lshs) strains of mice were challenged with amastigotes of Leishmania donovani and evaluated as to immune status at intervals between 2 and 40 weeks after challenge. The proliferative responses of splenic lymphocytes to T-cell mitogens, a B-cell mitogen, and parasite antigens were measured to evaluate the relative immune status of parasitized mice and noninfected control mice. Lymphocytes from resistant C3Heb/FeJ (C3H) mice responded normally to concanavalin A and phytohemagglutinin throughout the course of infection. Parasite antigen responses appeared 2 weeks after challenge of C3H mice and remained vigorous for periods up to 6 months. In contrast, immune suppression during infection was profound in both the curing (C57B1/10) and noncuring (B10.D2) phenotypes of Lshs congenic mice. Both Lshs strains developed severe infection as evidenced by high parasite burdens in the liver and spleen 4 to 5 weeks after challenge; splenic lymphocytes taken from these mice between 2 and 8 weeks became increasingly unresponsive to the T-cell mitogens as well as to parasite antigens. The noncuring B10.D2 mice which suffered chronic infection continued to be suppressed for as long as 40 weeks. C57B1/10 (curing) mice, in contrast, cleared infection between 12 and 16 weeks. After spontaneous recovery or elimination of parasites by antimonial drug therapy, the response of spleen cells to T-cell mitogens or parasite antigens were restored to normal. The spleen cells from the Lshs strains of mice obtained during the height of infection suppressed the proliferative responses of spleen cells from their uninfected counterparts upon cocultivation in vitro

  14. Penicillin Susceptibility and Macrolide-Lincosamide-Streptogramin B Resistance in Group B Streptococcus Isolates from a Canadian Hospital

    Directory of Open Access Journals (Sweden)

    Kevin Sherman

    2012-01-01

    Full Text Available BACKGROUND: Intrapartum antibiotic prophylaxis (IAP is recommended for pregnant women who test positive for group B Streptococcus (GBS in their genitourinary tract to prevent GBS-induced neonatal sepsis. Penicillin G is used as the primary antibiotic, and clindamycin or erythromycin as the secondary, if allergies exist. Decreased susceptibility to penicillin G has occasionally been reported; however, clindamycin and erythromycin resistance is on the rise and is causing concern over the use of clindamycin and erythromycin IAP.

  15. ramR mutations affecting fluoroquinolone susceptibility in epidemic multidrug-resistant Salmonella enterica serovar Kentucky ST198

    OpenAIRE

    Baucheron, Sylvie; Le Hello, Simon; Doublet, Benoît; Giraud, Etienne; Weill, François-Xavier; Cloeckaert, Axel

    2013-01-01

    International audience; A screening for non-target mutations affecting fluoroquinolone susceptibility was conducted in epidemic multidrug-resistant Salmonella enterica serovar Kentucky ST198. Among a panel of representative isolates (n = 27), covering the epidemic, only three showed distinct mutations in ramR resulting in enhanced expression of genes encoding the AcrAB-TolC efflux system and low increase in ciprofloxacin MIC. No mutations were detected in other regulatory regions of this effl...

  16. ramR mutations affecting fluoroquinolone susceptibility in epidemic multidrug-resistant Salmonella enterica serovar Kentucky ST198.

    Science.gov (United States)

    Baucheron, Sylvie; Le Hello, Simon; Doublet, Benoît; Giraud, Etienne; Weill, François-Xavier; Cloeckaert, Axel

    2013-01-01

    A screening for non-target mutations affecting fluoroquinolone susceptibility was conducted in epidemic multidrug-resistant Salmonella enterica serovar Kentucky ST198. Among a panel of representative isolates (n = 27), covering the epidemic, only three showed distinct mutations in ramR resulting in enhanced expression of genes encoding the AcrAB-TolC efflux system and low increase in ciprofloxacin MIC. No mutations were detected in other regulatory regions of this efflux system. Ciprofloxacin resistance in serovar Kentucky ST198 is thus currently mainly due to multiple target gene mutations.

  17. ramR Mutations Affecting Fluoroquinolone Susceptibility in Epidemic Multidrug-Resistant Salmonella enterica Serovar Kentucky ST198

    Directory of Open Access Journals (Sweden)

    Axel eCloeckaert

    2013-07-01

    Full Text Available A screening for non-target mutations affecting fluoroquinolone susceptibility was conducted in epidemic multidrug-resistant Salmonella enterica serovar Kentucky ST198. Among a panel of representative isolates (n=30, covering the epidemic, only three showed distinct mutations in ramR resulting in enhanced expression of genes encoding the AcrAB-TolC efflux system and low increase in ciprofloxacin MIC. No mutations were detected in other regulatory regions of this efflux system. Ciprofloxacin resistance in serovar Kentucky ST198 is thus currently mainly due to multiple target gene mutations.

  18. Impact of electric and magnetic fields in a resistant medium on the ...

    African Journals Online (AJOL)

    In this paper, we compare the impact of electric and magnetic fields in a resistant medium on the velocity of a particle subject to varying path angles by using numerical integration of finite difference method. The results show that the magnetic field has much impact on the velocity than the electric field. Journal of the Nigerian ...

  19. Reduced susceptibility to vancomycin and biofilm formation in methicillin-resistant Staphylococcus epidermidis isolated from blood cultures

    Directory of Open Access Journals (Sweden)

    Luiza Pinheiro

    2014-11-01

    Full Text Available This study aimed to correlate the presence of ica genes, biofilm formation and antimicrobial resistance in 107 strains of Staphylococcus epidermidis isolated from blood cultures. The isolates were analysed to determine their methicillin resistance, staphylococcal cassette chromosome mec (SCCmec type, ica genes and biofilm formation and the vancomycin minimum inhibitory concentration (MIC was measured for isolates and subpopulations growing on vancomycin screen agar. The mecA gene was detected in 81.3% of the S. epidermidis isolated and 48.2% carried SCCmec type III. The complete icaADBC operon was observed in 38.3% of the isolates; of these, 58.5% produced a biofilm. Furthermore, 47.7% of the isolates grew on vancomycin screen agar, with an increase in the MIC in 75.9% of the isolates. Determination of the MIC of subpopulations revealed that 64.7% had an MIC ≥ 4 μg mL-1, including 15.7% with an MIC of 8 μg mL-1 and 2% with an MIC of 16 μg mL-1. The presence of the icaADBC operon, biofilm production and reduced susceptibility to vancomycin were associated with methicillin resistance. This study reveals a high level of methicillin resistance, biofilm formation and reduced susceptibility to vancomycin in subpopulations of S. epidermidis. These findings may explain the selection of multidrug-resistant isolates in hospital settings and the consequent failure of antimicrobial treatment.

  20. Mtx toxins synergize Bacillus sphaericus and Cry11Aa against susceptible and insecticide-resistant Culex quinquefasciatus larvae.

    Science.gov (United States)

    Wirth, Margaret C; Yang, Yangkun; Walton, William E; Federici, Brian A; Berry, Colin

    2007-10-01

    Two mosquitocidal toxins (Mtx) of Bacillus sphaericus, which are produced during vegetative growth, were investigated for their potential to increase toxicity and reduce the expression of insecticide resistance through their interactions with other mosquitocidal proteins. Mtx-1 and Mtx-2 were fused with glutathione S-transferase and produced in Escherichia coli, after which lyophilized powders of these fusions were assayed against Culex quinquefasciatus larvae. Both Mtx proteins showed a high level of activity against susceptible C. quinquefasciatus mosquitoes, with 50% lethal concentrations (LC(50)) of Mtx-1 and Mtx-2 of 0.246 and 4.13 microg/ml, respectively. The LC(50)s were 0.406 to 0.430 microg/ml when Mtx-1 or Mtx-2 was mixed with B. sphaericus, and synergy improved activity and reduced resistance levels. When the proteins were combined with a recombinant Bacillus thuringiensis strain that produces Cry11Aa, the mixtures were highly active against Cry11A-resistant larvae and resistance was also reduced. The mixture of two Mtx toxins and B. sphaericus was 10 times more active against susceptible mosquitoes than B. sphaericus alone, demonstrating the influence of relatively low concentrations of these toxins. These results show that, similar to Cyt toxins from B. thuringiensis subsp. israelensis, Mtx toxins can increase the toxicity of other mosquitocidal proteins and may be useful for both increasing the activity of commercial bacterial larvicides and managing potential resistance to these substances among mosquito populations.

  1. Characterizing root system characteristics with Electrical resistivity Tomography: a virtual rhizotron simulation

    OpenAIRE

    Rao, Sathyanarayan; Ehosioke, Solomon; Lesparre, Nolwenn; Nguyen, Frédéric; Javaux, Mathieu

    2017-01-01

    Electrical Resistivity Tomography (ERT) is more and more used for monitoring soil water content in a cropped soil. Yet, the impact of roots on the signal is often neglected and a topic of controversy. In several studies related to soil-root system, it has been showed that the measured root mass density statistically correlates with the electrical conductivity (EC) data obtained from ERT. In addition, some studies suggest that some roots are more electrically conductive than soil f...

  2. Modified alpha-amylase activity among insecticide-resistant and -susceptible strains of the maize weevil, Sitophilus zeamais.

    Science.gov (United States)

    Lopes, K V G; Silva, L B; Reis, A P; Oliveira, M G A; Guedes, R N C

    2010-09-01

    Fitness cost is usually associated with insecticide resistance and may be mitigated by increased energy accumulation and mobilization. Preliminary evidence in the maize weevil (Coleoptera: Curculionidae) suggested possible involvement of amylases in such phenomenon. Therefore, alpha-amylases were purified from an insecticide-susceptible and two insecticide-resistant strains (one with fitness cost [resistant cost strain], and the other without it [resistant no-cost strain]). The main alpha-amylase of each strain was purified by glycogen precipitation and ion-exchange chromatography (>or=70-fold purification, cost strain exhibited higher activity towards starch and lower inhibition by acarbose and wheat amylase inhibitors. Opposite results were observed for the alpha-amylase from the resistant cost strain. Although the alpha-amylase from the resistant cost strain exhibited higher affinity to starch (i.e., lower K(m)), its V(max)-value was the lowest among the strains, particularly the resistant no-cost strain. Such results provide support for the hypothesis that enhanced alpha-amylase activity may be playing a major role in mitigating fitness costs associated with insecticide resistance.

  3. Transcriptome Analysis of Cotton (Gossypium hirsutum L. Genotypes That Are Susceptible, Resistant, and Hypersensitive to Reniform Nematode (Rotylenchulus reniformis.

    Directory of Open Access Journals (Sweden)

    Ruijuan Li

    Full Text Available Reniform nematode is a semi-endoparasitic nematode species causing significant yield loss in numerous crops, including cotton (Gossypium hirsutum L.. An RNA-sequencing analysis was conducted to measure transcript abundance in reniform nematode susceptible (DP90 & SG747, resistant (BARBREN-713, and hypersensitive (LONREN-1 genotypes of cotton (Gossypium hirsutum L. with and without reniform nematode infestation. Over 90 million trimmed high quality reads were assembled into 84,711 and 80, 353 transcripts using the G. arboreum and the G. raimondii genomes as references. Many transcripts were significantly differentially expressed between the three different genotypes both prior to and during nematode pathogenesis, including transcripts corresponding to the gene ontology categories of cell wall, hormone metabolism and signaling, redox reactions, secondary metabolism, transcriptional regulation, stress responses, and signaling. Further analysis revealed that a number of these differentially expressed transcripts mapped to the G. raimondii and/or the G. arboreum genomes within 1 megabase of quantitative trait loci that had previously been linked to reniform nematode resistance. Several resistance genes encoding proteins known to be strongly linked to pathogen perception and resistance, including LRR-like and NBS-LRR domain-containing proteins, were among the differentially expressed transcripts mapping near these quantitative trait loci. Further investigation is required to confirm a role for these transcripts in reniform nematode susceptibility, hypersensitivity, and/or resistance. This study presents the first systemic investigation of reniform nematode resistance-associated genes using different genotypes of cotton. The candidate reniform nematode resistance-associated genes identified in this study can serve as the basis for further functional analysis and aid in further development of reniform a nematode resistant cotton germplasm.

  4. Transcriptome Analysis of Cotton (Gossypium hirsutum L.) Genotypes That Are Susceptible, Resistant, and Hypersensitive to Reniform Nematode (Rotylenchulus reniformis).

    Science.gov (United States)

    Li, Ruijuan; Rashotte, Aaron M; Singh, Narendra K; Lawrence, Kathy S; Weaver, David B; Locy, Robert D

    2015-01-01

    Reniform nematode is a semi-endoparasitic nematode species causing significant yield loss in numerous crops, including cotton (Gossypium hirsutum L.). An RNA-sequencing analysis was conducted to measure transcript abundance in reniform nematode susceptible (DP90 & SG747), resistant (BARBREN-713), and hypersensitive (LONREN-1) genotypes of cotton (Gossypium hirsutum L.) with and without reniform nematode infestation. Over 90 million trimmed high quality reads were assembled into 84,711 and 80, 353 transcripts using the G. arboreum and the G. raimondii genomes as references. Many transcripts were significantly differentially expressed between the three different genotypes both prior to and during nematode pathogenesis, including transcripts corresponding to the gene ontology categories of cell wall, hormone metabolism and signaling, redox reactions, secondary metabolism, transcriptional regulation, stress responses, and signaling. Further analysis revealed that a number of these differentially expressed transcripts mapped to the G. raimondii and/or the G. arboreum genomes within 1 megabase of quantitative trait loci that had previously been linked to reniform nematode resistance. Several resistance genes encoding proteins known to be strongly linked to pathogen perception and resistance, including LRR-like and NBS-LRR domain-containing proteins, were among the differentially expressed transcripts mapping near these quantitative trait loci. Further investigation is required to confirm a role for these transcripts in reniform nematode susceptibility, hypersensitivity, and/or resistance. This study presents the first systemic investigation of reniform nematode resistance-associated genes using different genotypes of cotton. The candidate reniform nematode resistance-associated genes identified in this study can serve as the basis for further functional analysis and aid in further development of reniform a nematode resistant cotton germplasm.

  5. Susceptibility of Varroa destructor (Acari: Varroidae) to synthetic acaricides in Uruguay: Varroa mites' potential to develop acaricide resistance.

    Science.gov (United States)

    Maggi, Matías Daniel; Ruffinengo, Sergio Roberto; Mendoza, Yamandú; Ojeda, Pilar; Ramallo, Gustavo; Floris, Iganazio; Eguaras, Martín Javier

    2011-04-01

    The purpose of this study was to estimate the acaricide susceptibility of Varroa destructor populations from Uruguay, which had never been exposed to synthetic acaricides. It was also to determine whether acaricide resistance to coumaphos occurred in apiaries in which acaricide rotation had been applied. Bioassays with acaricides against mite populations that had never been exposed to synthetic acaricides were performed, also against mite populations in which control failures with coumaphos had been reported. Additionally, coumaphos' effectiveness in honeybee colonies was experimentally tested. The lethal concentration that kills 50% of the exposed animals (LC(50)) for susceptible mite populations amounted to 0.15 μg/Petri dish for coumaphos and to less than 0.3 μg/Petri dish for the other acaricides. Coumaphos LC(50) was above 40 μg/Petri dish for resistant mites. The effectiveness of coumaphos in honeybee colonies parasitized by V. destructor ranged from 17.6% to 93.9%. LC(50) for mite populations susceptible to the most commonly applied miticides was determined, and the first case of coumaphos resistance recorded in Uruguay was established.

  6. The value of microscopic-observation drug susceptibility assay in the diagnosis of tuberculosis and detection of multidrug resistance.

    Science.gov (United States)

    Sertel Şelale, Denİz; Uzun, Meltem

    2018-01-01

    Inexpensive, rapid, and reliable tests for detecting the presence and drug susceptibility of Mycobacterium tuberculosis complex (MTBC) are urgently needed to control the transmission of tuberculosis. In this study, we aimed to assess the accuracy and speed of the microscopic-observation drug susceptibility (MODS) assay in the identification of MTBC and detection of multidrug resistance. Sputum samples from patients suspected to have tuberculosis were simultaneously tested with MODS and conventional culture [Löwenstein-Jensen (LJ) culture, BACTEC MGIT™ 960 (MGIT) system], and drug susceptibility testing (MGIT system) methods. A total of 331 sputum samples were analyzed. Sensitivity and specificity of MODS assay for detection of MTBC strains were 96% and 98.8%, respectively. MODS assay detected multidrug resistant MTBC isolates with 92.3% sensitivity and 96.6% specificity. Median time to culture positivity was similar for MGIT (8 days) and MODS culture (8 days), but was significantly longer with LJ culture (20 days) (p tuberculosis and detection of multidrug resistance. © 2017 APMIS. Published by John Wiley & Sons Ltd.

  7. The Leukotriene B4/BLT1 Axis Is a Key Determinant in Susceptibility and Resistance to Histoplasmosis

    Science.gov (United States)

    Secatto, Adriana; Soares, Elyara Maria; Locachevic, Gisele Aparecida; Assis, Patricia Aparecida; Paula-Silva, Francisco Wanderlei Garcia; Serezani, Carlos Henrique; de Medeiros, Alexandra Ivo; Faccioli, Lúcia Helena

    2014-01-01

    The bioactive lipid mediator leukotriene B4 (LTB4) greatly enhances phagocyte antimicrobial functions against a myriad of pathogens. In murine histoplasmosis, inhibition of the LT-generating enzyme 5-lypoxigenase (5-LO) increases the susceptibility of the host to infection. In this study, we investigated whether murine resistance or susceptibility to Histoplasma capsulatum infection is associated with leukotriene production and an enhancement of in vivo and/or in vitro antimicrobial effector function. We show that susceptible C57BL/6 mice exhibit a higher fungal burden in the lung and spleen, increased mortality, lower expression levels of 5-LO and leukotriene B4 receptor 1 (BLT1) and decreased LTB4 production compared to the resistant 129/Sv mice. Moreover, we demonstrate that endogenous and exogenous LTs are required for the optimal phagocytosis of H. capsulatum by macrophages from both murine strains, although C57BL/6 macrophages are more sensitive to the effects of LTB4 than 129/Sv macrophages. Therefore, our results provide novel evidence that LTB4 production and BLT1 signaling are required for a histoplasmosis-resistant phenotype. PMID:24465479

  8. Conjunctivitis Caused by Neisseria gonorrhoeae Isolates with Reduced Cephalosporin Susceptibility and Multidrug Resistance

    Science.gov (United States)

    Kitagawa, Yutaka; Maruyama, Yosuke; Yamaguchi, Satoshi; Sakane, Yuri; Miyamoto, Hitoshi; Ohashi, Yuichi

    2013-01-01

    We report two cases of conjunctivitis caused by Neisseria gonorrhoeae with reduced cephalosporin susceptibility. Patients showed no response to cefmenoxime eye drops and intravenous ceftriaxone administration. The patients' condition improved after the addition of oral minocycline. The isolates contained the mosaic penA for reduction of β-lactam susceptibility. PMID:24025911

  9. Antibacterial susceptibility patterns and cross-resistance of methicillin resistant and sensitive Staphyloccus aureus isolated from the hospitalized patients in Shiraz, Iran

    Directory of Open Access Journals (Sweden)

    Aziz Japoni

    2010-10-01

    Full Text Available Nosocomial infections caused by methicillin-resistant staphylococci (MRSA pose a serious problem in many countries. This study aimed to determine the antibacterial susceptibility patterns of methicillin sensitive and resistant Staphylococcus aureus isolates from the hospitalized patients. Totally 356 isolates of Staphylococcus aureus (S. aureus including 200, 137 and 19 corresponding to MSSA, MRSA, and intermediate MRSA strains, respectively were isolated. Antibacterial susceptibility patterns of the isolates to 14 antibiotics were examined using Kirby-Bauer method. MICs of 15 antibiotics to 156 MRSA isolates were determined by E test method. Cross-resistances of MRSA isolates (137+19 to the other tested antibiotics were also determined. S.aureus with high frequencies were isolated from the blood, sputum and deep wound samples. All of 200 MSSA isolates were sensitive to oxacillin, vancomycin, tecoplanin, rifampin, linezolid, quinupristin/dalfopristin, mupirocin and fusidic acid. A gradient of reduced susceptibility of MSSA to cephalexin, co-trimoxazole, ciprofloxacin, clindamycin, tetracycline, erythromycin and gentamicin were evident. MRSA isolates were sensitive to vancomycin, tecoplanin, linezolid, quinupristin/dalfopristin, mupirocin and fusidic acid, while reduced susceptibility of them to rifampin, co-trimoxazole, clindamycin, cephalexin, tetracycline, ciprofloxacin, erythromycin and gentamicin were observed. MRSA isolates exhibited a high range of cross-resistance to the eight tested antibiotics. Overall, co-trimoxazole, ciprofloxacin, clindamycin, tetracycline, erythromycin and gentamicin showed low activity against MSSA and MRSA isolates which may indicate they are not suitable to be used in clinical practices. To preserve the effectiveness of antibiotics, rational prescription and concomitant application of preventive measures against the spread of MRSA are recommended.

  10. electrical resistivity investigation of the groundwater potential in ...

    African Journals Online (AJOL)

    (VES) within the IOT campus using Allied Omega digital. Resistivity equipment. The Schlumberger electrode configuration was used, with maximum current electrode separation (AB/2) of 50m. The instrument, in this array measures vertical changes in ground resistivity with depth. This is the preferred way to locate vertical ...

  11. Critical behavior of electrical resistivity in amorphous Fe–Zr alloys

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... Electrical resistivity (ρ) of the amorphous (a-)Fe100-Zr ( = 8.5, 9.5 and 10) alloys has been measured in the temperature range 77 to 300 K, which embraces the second-order magnetic phase transition at the Curie temperature point . Analysis of the resistivity data particularly in the critical region ...

  12. Electrical Resistivity of Natural Diamond and Diamond Films Between Room Temperature and 1200 C: Status Update

    Science.gov (United States)

    Vandersande, Jan W.; Zoltan, L. D.

    1993-01-01

    The electrical resistivity of diamond films has been measured between room temperature and 1200 C. The films were grown by either microwave Plasma CVD or combustion flame at three different places. The resistivities of the current films are compared to those measured for both natural IIa diamond and films grown only one to two years ago.

  13. Electrical resistivity of quartzite obtained from the gold-belt of the ...

    African Journals Online (AJOL)

    The variation of the electrical resistivity between room temperature (300 K) and elevated temperature (500 K) has been investigated for quartzite obtained from the Gold Belt of the Tarkwaian rock formation in the south-western part of Ghana. The resistivity was measured for the passage of current through the samples in two ...

  14. Evaluation of polymorphisms in pbp4 gene and genetic diversity in penicillin-resistant, ampicillin-susceptible Enterococcus faecalis from hospitals in different states in Brazil.

    Science.gov (United States)

    Infante, Victor Hugo Pacagnelli; Conceição, Natália; de Oliveira, Adriana Gonçalves; Darini, Ana Lúcia da Costa

    2016-04-01

    The aim of the present study was to verify whether penicillin-resistant, ampicillin-susceptible Enterococcus faecalis (PRASEF) occurred in Brazil prior to the beginning of the 21st century, and to verify whether ampicillin susceptibility can predict susceptibility to other β-lactams in E. faecalis with this inconsistent phenotype. The presence of polymorphisms in the pbp4 gene and genetic diversity among the isolates were investigated. Of 21 PRASEF analyzed, 5 (23.8%) and 4 (19.0%) were imipenem and piperacillin resistant simultaneously by disk diffusion and broth dilution respectively, contradicting the current internationally accepted standards of susceptibility testing. Sequencing of pbp4 gene revealed an amino acid substitution (Asp-573→Glu) in all PRASEF isolates but not in the penicillin-susceptible, ampicillin-susceptible E. faecalis. Most PRASEF (90.5%) had related pulsed-field gel electrophoresis profiles, but were different from other PRASEF described to date. Results demonstrate that penicillin-resistant, ampicillin-susceptible phenotype was already a reality in the 1990s in E. faecalis isolates in different Brazilian states, and some of these isolates were also imipenem- and piperacillin-resistant; therefore, internationally accepted susceptibility criteria cannot be applied to these isolates. According to pbp4 gene sequencing, this study suggests that a specific amino acid substitution in pbp4 gene found in all PRASEF analyzed is associated with penicillin resistance. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Emergence of Ceftazidime-Avibactam Resistance and Restoration of Carbapenem Susceptibility inKlebsiella pneumoniaeCarbapenemase-ProducingK pneumoniae: A Case Report and Review of Literature.

    Science.gov (United States)

    Shields, Ryan K; Nguyen, M Hong; Press, Ellen G; Chen, Liang; Kreiswirth, Barry N; Clancy, Cornelius J

    2017-01-01

    We used meropenem to successfully treat a patient with bacteremia due to ceftazidime-avibactam-resistant, meropenem- susceptible Klebsiella pneumoniae that carried mutant bla KPC-3 . Meropenem was bactericidal against ceftazidime-avibactam- resistant K pneumoniae isolates in vitro. Nevertheless, the role of carbapenems in treating such infections remains uncertain, because meropenem resistance is selected readily during passage experiments.

  16. Direct localised measurement of electrical resistivity profile in rat and embryonic chick retinas using a microprobe

    Directory of Open Access Journals (Sweden)

    Harald van Lintel

    2010-01-01

    Full Text Available We report an alternative technique to perform a direct and local measurement of electrical resistivities in a layered retinal tissue. Information on resistivity changes along the depth in a retina is important for modelling retinal stimulation by retinal prostheses. Existing techniques for resistivity-depth profiling have the drawbacks of a complicated experimental setup, a less localised resistivity probing and/or lower stability for measurements. We employed a flexible microprobe to measure local resistivity with bipolar impedance spectroscopy at various depths in isolated rat and chick embryo retinas for the first time. Small electrode spacing permitted high resolution measurements and the probe flexibility contributed to stable resistivity profiling. The resistivity was directly calculated based on the resistive part of the impedance measured with the Peak Resistance Frequency (PRF methodology. The resistivity-depth profiles for both rat and chick embryo models are in accordance with previous mammalian and avian studies in literature. We demonstrate that the measured resistivity at each depth has its own PRF signature. Resistivity profiles obtained with our setup provide the basis for the construction of an electric model of the retina. This model can be used to predict variations in parameters related to retinal stimulation and especially in the design and optimisation of efficient retinal implants.

  17. Characterizing soil erosion potential using electrical resistivity imaging : final report.

    Science.gov (United States)

    2017-04-01

    The erosion rate, or erodibility, of soil depends on many soil characteristics including: plasticity, : water content, grain size, percent clay, compaction, and shear strength. Many of these characteristics also : influence soil in situ bulk electric...

  18. Characterizing soil erosion potential using electrical resistivity imaging : technical summary.

    Science.gov (United States)

    2017-04-01

    The erosion rate, or erodibility, of soil depends on many soil characteristics : including: plasticity, water content, grain size, percent clay, compaction, and shear : strength. Many of these characteristics also influence soil in situ bulk electric...

  19. Electric fields, weighting fields, signals and charge diffusion in detectors including resistive materials

    CERN Document Server

    Riegler, Werner

    2016-11-07

    In this report we discuss static and time dependent electric fields in detector geometries with an arbitrary number of parallel layers of a given permittivity and weak conductivity. We derive the Green's functions i.e. the field of a point charge, as well as the weighting fields for readout pads and readout strips in these geometries. The effect of 'bulk' resistivity on electric fields and signals is investigated. The spreading of charge on thin resistive layers is also discussed in detail, and the conditions for allowing the effect to be described by the diffusion equation is discussed. We apply the results to derive fields and induced signals in Resistive Plate Chambers, Micromega detectors including resistive layers for charge spreading and discharge protection as well as detectors using resistive charge division readout like the MicroCAT detector. We also discuss in detail how resistive layers affect signal shapes and increase crosstalk between readout electrodes.

  20. Changes in electrical resistance of sound fissure enamel in first molars for 66 months from eruption.

    Science.gov (United States)

    Kataoka, S; Sakuma, S; Wang, J; Yoshihara, A; Miyazaki, H

    2007-01-01

    The purposes of this study were to investigate the enamel maturation process in the occlusal pit of sound first molars by measuring electrical resistance. Ninety-nine sound first molars in 34 children (mean age of 6.47 +/- 0.51 years) were measured electrically once every 6 months and were monitored for a maximum of 66 months. Electrical resistance increased during the posteruptive period. However, the results suggest that posteruptive enamel maturation in the occlusal pits may not be completed even 66 months after tooth eruption. Copyright 2007 S. Karger AG, Basel.

  1. Electrical resistance of CNT-PEEK composites under compression at different temperatures

    Directory of Open Access Journals (Sweden)

    Mohiuddin Mohammad

    2011-01-01

    Full Text Available Abstract Electrically conductive polymers reinforced with carbon nanotubes (CNTs have generated a great deal of scientific and industrial interest in the last few years. Advanced thermoplastic composites made of three different weight percentages (8%, 9%, and 10% of multiwalled CNTs and polyether ether ketone (PEEK were prepared by shear mixing process. The temperature- and pressure-dependent electrical resistance of these CNT-PEEK composites have been studied and presented in this paper. It has been found that electrical resistance decreases significantly with the application of heat and pressure.

  2. Colonization of resistant and susceptible lettuce cultivars by a green fluorescent protein-tagged isolate of Verticillium dahliae.

    Science.gov (United States)

    Vallad, G E; Subbarao, K V

    2008-08-01

    Interactions between lettuce and a green fluorescent protein (GFP)-expressing, race 1 isolate of Verticillium dahliae, were studied to determine infection and colonization of lettuce cultivars resistant and susceptible to Verticillium wilt. The roots of lettuce seedlings were inoculated with a conidial suspension of the GFP-expressing isolate. Colonization was studied with the aid of laser scanning confocal and epi-fluorescence microscopes. Few differences in the initial infection and colonization of lateral roots were observed between resistant and susceptible cultivars. Hyphal colonies formed on root tips and within the root elongation zones by 5 days, leading to the colonization of cortical tissues and penetration of vascular elements regardless of the lettuce cultivar by 2 weeks. By 8 to 10 weeks after inoculation, vascular discoloration developed within the taproot and crown regions of susceptible cultivars well in advance of V. dahliae colonization. Actual foliar wilt coincided with the colonization of the taproot and crown areas and the eruption of mycelia into surrounding cortical tissues. Advance colonization of stems, pedicels, and inflorescence, including developing capitula and mature achenes was observed. Seedborne infection was limited to the maternal tissues of the achene, including the pappus, pericarp, integument, and endosperm; but the embryo was never compromised. Resistant lettuce cultivars remained free of disease symptoms. Furthermore, V. dahliae colonization never progressed beyond infected lateral roots of resistant cultivars. Results indicated that resistance in lettuce may lie with the plant's ability to shed infected lateral roots or to inhibit the systemic progress of the fungus through vascular tissues into the taproot.

  3. A first insight into the involvement of phytohormones pathways in coffee resistance and susceptibility to Colletotrichum kahawae

    Science.gov (United States)

    Figueiredo, Andreia; Loureiro, Andreia; Batista, Dora; Azinheira, Helena; Várzea, Vítor; Pereira, Ana Paula; Gichuru, Elijah; Moncada, Pilar; Guerra-Guimarães, Leonor; Oliveira, Helena; Silva, Maria do Céu

    2017-01-01

    Understanding the molecular mechanisms underlying coffee-pathogen interactions are of key importance to aid disease resistance breeding efforts. In this work the expression of genes involved in salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) pathways were studied in hypocotyls of two coffee varieties challenged with the hemibiotrophic fungus Colletotrichum kahawae, the causal agent of Coffee Berry Disease. Based on a cytological analysis, key time-points of the infection process were selected and qPCR was used to evaluate the expression of phytohormones biosynthesis, reception and responsive-related genes. The resistance to C. kahawae was characterized by restricted fungal growth associated with early accumulation of phenolic compounds in the cell walls and cytoplasmic contents, and deployment of hypersensitive reaction. Similar responses were detected in the susceptible variety, but in a significantly lower percentage of infection sites and with no apparent effect on disease development. Gene expression analysis suggests a more relevant involvement of JA and ET phytohormones than SA in this pathosystem. An earlier and stronger activation of the JA pathway observed in the resistant variety, when compared with the susceptible one, seems to be responsible for the successful activation of defense responses and inhibition of fungal growth. For the ET pathway, the down or non-regulation of ET receptors in the resistant variety, together with a moderate expression of the responsive-related gene ERF1, indicates that this phytohormone may be related with other functions besides the resistance response. However, in the susceptible variety, the stronger activation of ERF1 gene at the beginning of the necrotrophic phase, suggests the involvement of ET in tissue senescence. As far as we know, this is the first attempt to unveil the role of phytohormones in coffee-C. kahawae interactions, thus contributing to deepen our understanding on the complex mechanisms of plant

  4. A first insight into the involvement of phytohormones pathways in coffee resistance and susceptibility to Colletotrichum kahawae.

    Science.gov (United States)

    Diniz, Inês; Figueiredo, Andreia; Loureiro, Andreia; Batista, Dora; Azinheira, Helena; Várzea, Vítor; Pereira, Ana Paula; Gichuru, Elijah; Moncada, Pilar; Guerra-Guimarães, Leonor; Oliveira, Helena; Silva, Maria do Céu

    2017-01-01

    Understanding the molecular mechanisms underlying coffee-pathogen interactions are of key importance to aid disease resistance breeding efforts. In this work the expression of genes involved in salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) pathways were studied in hypocotyls of two coffee varieties challenged with the hemibiotrophic fungus Colletotrichum kahawae, the causal agent of Coffee Berry Disease. Based on a cytological analysis, key time-points of the infection process were selected and qPCR was used to evaluate the expression of phytohormones biosynthesis, reception and responsive-related genes. The resistance to C. kahawae was characterized by restricted fungal growth associated with early accumulation of phenolic compounds in the cell walls and cytoplasmic contents, and deployment of hypersensitive reaction. Similar responses were detected in the susceptible variety, but in a significantly lower percentage of infection sites and with no apparent effect on disease development. Gene expression analysis suggests a more relevant involvement of JA and ET phytohormones than SA in this pathosystem. An earlier and stronger activation of the JA pathway observed in the resistant variety, when compared with the susceptible one, seems to be responsible for the successful activation of defense responses and inhibition of fungal growth. For the ET pathway, the down or non-regulation of ET receptors in the resistant variety, together with a moderate expression of the responsive-related gene ERF1, indicates that this phytohormone may be related with other functions besides the resistance response. However, in the susceptible variety, the stronger activation of ERF1 gene at the beginning of the necrotrophic phase, suggests the involvement of ET in tissue senescence. As far as we know, this is the first attempt to unveil the role of phytohormones in coffee-C. kahawae interactions, thus contributing to deepen our understanding on the complex mechanisms of plant

  5. Characterization of pyrethroid resistance and susceptibility to coumaphos in Mexican Boophilus microplus (Acari: Ixodidae).

    Science.gov (United States)

    Miller, R J; Davey, R B; George, J E

    1999-09-01

    Two patterns of pyrethroid resistance were characterized from Boophilus microplus (Canestrini) collected in Mexico. One was characteristic of a kdr mutation and the other involved esterase and cytochrome P450 enzyme systems. Very high resistance to permethrin, cypermethrin, and flumethrin, not synergized by TPP and PBO and high resistance to DDT, characterized the kdr-like pattern found in the Corrales and San Felipe strains. Esterase and cytochrome P450-dependent resistance was found in the Coatzacoalcos strain. It was characterized by resistance to permethrin, cypermethrin, and flumethrin, synergized by TPP and PBO, but no resistance to DDT. The Coatzacoalcos strain also showed 3.6-fold resistance to the organophosphate coumaphos. This factor appeared to be independent of pyrethroid resistance. Pyrethroid resistance patterns found in Mexico were similar to those found earlier in Australia. The significance of pyrethroid and coumaphos resistance to the U.S. cattle fever tick quarantine is discussed.

  6. Thickness effect on electric resistivity on polystyrene and carbon black- based composites

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Lopez, S; Vigueras-Santiago, E [Laboratorio de Investigacion y Desarrollo de Materiales Avanzados (LIDMA) Facultad de Quimica, Paseo Colon Esquina con Paseo Tollocan, s/n, CP 50000, Toluca (Mexico); Mayorga-Rojas, M; Reyes-Contreras, D, E-mail: eviguerass@uaemex.m [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico. Av. Instituto Literario 100 Ote. C. P. 50000, Toluca (Mexico)

    2009-05-01

    Changes on electrical resistivity were experimentally studied for polystyrene and carbon black-based composites respect to the temperature. 22% w/w carbon black composite films at 30{mu}m, 2mm y 1cm thick were submitted to thermal heating-cooling cycles from room temperature to 100 deg. C, slightly up to T{sub g} of the composite. For each cycle changes on electrical resistivity constituent a hysteresis loop that depends on the sample thickness. The changes during the heating stage could be explained as a consequence of the thermal expansion and mobility of the polymer chains at T{sub g}, producing a disconnecting of the electrical contacts among carbon black particles and an important increasing (200%) of the electrical resistivity. For each cycle, the hysteresis loop was observed in thicker samples, whereas for 30 mu m thickness sample the hysteresis loop was lost after four cycles.

  7. Study on aerodynamic resistance to electric rail vehicles generated by the power supply

    Directory of Open Access Journals (Sweden)

    Ioan SEBESAN

    2014-04-01

    Full Text Available Improving the traction performance of the electric railway vehicles requires an analysis to reduce their aerodynamic resistance. These vehicles cannot be set in motion without an external power source, which demonstrates that the supply system is a key-element to their operation. The power source is located on the rooftop which basically results in an increase of their aerodynamic resistance. The present study discusses the aerodynamic resistance of the electric railway equipment such as pantographs, automatic circuit breaker, insulators, etc. The analyze is based on the equipment installed on the electric locomotive LE 060 EA of 5100 kW which is operational in Romania, emphasizing the pantographs role in capturing of electricity.

  8. Examination of Electrical Resistance of Carburizers Used for Cast Iron Production

    Directory of Open Access Journals (Sweden)

    Książek D.

    2016-12-01

    Full Text Available The publication presents the results of examination of selected carburizers used for cast iron production with respect to their electric resistance. Both the synthetic graphite carburizers and petroleum coke (petcoke carburizers of various chemical composition were compared. The relationships between electrical resistance of tested carburizers and their quality were found. The graphite carburizers exhibited much better conductivity than the petcoke ones. Resistance characteristics were different for the different types of carburizers. The measurements were performed according to the authors’ own method based on recording the electric current flow through the compressed samples. The samples of the specified diameter were put under pressure of the gradually increased value (10, 20, 50, 60, and finally 70 bar, each time the corresponding value of electric resistance being measured with a gauge of high accuracy, equal to 0.1μΩ. The higher pressure values resulted in the lower values of resistance. The relation between both the thermal conductance and the electrical conductance (or the resistance is well known and mentioned in the professional literature. The results were analysed and presented both in tabular and, additionally, in graphic form.

  9. Trends in antimicrobial susceptibility among isolates of Campylobacter species in Ireland and the emergence of resistance to ciprofloxacin.

    LENUS (Irish Health Repository)

    Lucey, B

    2012-02-03

    Measurements were made of the susceptibility to six commonly prescribed antibiotics, including erythromycin, tetracycline and ciprofloxacin, of 130 isolates of Campylobacterjejuni and 15 isolates of Campylobacter coli cultured from human and poultry sources during 2000. The results were compared with the results from a collection of strains isolated between 1996 and 1998. The levels of resistance to erythromycin remained low, 2 per cent and 4.4 per cent for the human and poultry isolates, respectively. Resistance to tetracycline had increased to 31 per cent and 24.4 per cent from 13.9 per cent and 18.8 per cent for the human and poultry isolates, respectively. However, the resistance to ciprofloxacin of the strains isolated during 2000 had increased to 30 per cent, whereas between 1996 and 1998 there had been no resistance to this agent among human isolates, and only 3.1 per cent resistance among poultry isolates. The molecular basis for this resistance has been shown to be the result of a single amino acid substitution, Thr-86-Ile, in the gyrA subunit of DNA gyrase in Cjejuni. A subset of 59 isolates was tested by molecular methods and all of the 25 phenotypically resistant isolates possessed this substitution. None of the human isolates had been treated with ciprofloxacin before their laboratory isolation.

  10. Antimicrobial susceptibility of clinical isolates of Actinomyces and related genera reveals an unusual clindamycin resistance among Actinomyces urogenitalis strains.

    Science.gov (United States)

    Barberis, Claudia; Budia, Mabel; Palombarani, Susana; Rodriguez, Carlos Hernán; Ramírez, María Soledad; Arias, Barbara; Bonofiglio, Laura; Famiglietti, Angela; Mollerach, Marta; Almuzara, Marisa; Vay, Carlos

    2017-03-01

    Patterns of antimicrobial susceptibility in Actinomyces and related genera are very limited in the literature. Data of predominant susceptibility profiles could contribute to the establishment of an accurate empirical treatment. A total of 113 isolates from clinical samples were included in this study. Each isolate was identified using phenotypic methods and MALDI-TOF/MS. When discrepancies were observed, 16S rRNA gene sequencing was performed. The minimum inhibitory concentrations (MICs) of nine antimicrobial agents (penicillin, ceftriaxone, linezolid, tetracycline, clindamycin, erythromycin, ciprofloxacin, levofloxacin and vancomycin) were tested against the species Actinotignum schaalii (n=23), Actinomyces turicensis (n=18), Actinomyces europaeus (n=13), Actinomyces naeslundii/Actinomyces viscosus group (n=12), Actinomyces urogenitalis (n=11), Actinomyces radingae (n=11), Actinomyces neuii (n=9), Actinomyces odontolyticus (n=8), Bifidobacterium scardovii (n=3), Actinomyces graevenitzii (n=2), Alloscardovia omnicolens (n=2) and Varibaculum cambriense (n=1). All of the isolates were susceptible to penicillin, ceftriaxone, vancomycin and linezolid. Almost all of the A. urogenitalis isolates (8/11) were resistant to clindamycin and showed susceptibility to erythromycin, suggesting an L-phenotype, however no determinants of clindamycin resistance (lnu and lsa genes) were detected by PCR. High MIC values to quinolones were observed in 54/113 isolates (47.8%). All of the A. urogenitalis isolates were highly resistant to ciprofloxacin and levofloxacin. These data highlight the importance of ongoing surveillance to provide relevant information for empirical management of infections caused by these organisms. Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

  11. Modelling the influence of steel fibres on the electrical resistivity of cementitious composites

    DEFF Research Database (Denmark)

    Solgaard, Anders Ole Stubbe; Michel, Alexander; Stang, Henrik

    2009-01-01

    One of the governing factors on the corrosion of embedded reinforcement is the electrical resistivity of the concrete. The combination of steel fibres and conventional reinforcement bars has been used in a number of structures. However, the addition of electrical con-ductive fibres might influence...... of steel fibre reinforced concrete (SFRC). The parameters investigated in the following are the fibre geometry, the fibre volume and the transitional resistance. On basis of the experimental results, a model, taking the resistivity of the fibres and the concrete matrix into account is proposed....... the overall resistivity of the material and thereby the corrosion rate of the embedded reinforcement. To the knowledge of the authors, only preliminary studies have been made on the influence of corrosion of the reinforcement bars from the addition of the electrical conductive steel fibres. Thus the present...

  12. The effect of mechanical stress on electric resistance of nanographite-epoxy composites

    Science.gov (United States)

    Vovchenko, L.; Lazarenko, A.; Matzui, L.; Zhuravkov, A.

    2012-03-01

    The in-plane electric resistance Ra of composite materials (CMs) thermoexfoliated graphite(TEG)-epoxy resin(ED) under compression along compacting C-axis has been investigated by four-probe method. TEG content was 5-75 wt%. It was shown that specimens prepared by cold pressing are denser and reveal lower values of electric resistivity in comparison with specimens prepared by pouring. It was found that compression of the specimens leads to plastic deformation of specimens (εpl) and essential irreversible decrease of electric resistance during the first cycle of loading (up to 50 MPa), especially for the poured specimens with low density. Within the proposed model the contact resistance Rk between graphite particles in CM has been evaluated and it was shown that it increased with the decrease in TEG content in CM and depends on compacting method of CMs and the dispersity of graphite filler.

  13. Application of column tests and electrical resistivity methods for leachate transport monitoring

    Directory of Open Access Journals (Sweden)

    Wychowaniak Dorota

    2015-09-01

    Full Text Available Development of the human civilization leads to the pollution of environment. One of the contamination which are a real threat to soil and groundwater are leachates from landfills. In this paper the solute transport through soil was considered. For this purpose, the laboratory column tests of chlorides tracer and leachates transport on two soil samples have been carried out. Furthermore, the electrical resistivity method was applied as auxiliary tool to follow the movements of solute through the soil column what allowed to compare between the results obtained with column test method and electrical resistivity measurements. Breakthrough curves obtained by conductivity and resistivity methods represents similar trends which leads to the conclusion about the suitability of electrical resistivity methods for contamination transport monitoring in soil-water systems.

  14. Electrical resistance of individual defects at a topological insulator surface

    Science.gov (United States)

    Lüpke, Felix; Eschbach, Markus; Heider, Tristan; Lanius, Martin; Schüffelgen, Peter; Rosenbach, Daniel; von den Driesch, Nils; Cherepanov, Vasily; Mussler, Gregor; Plucinski, Lukasz; Grützmacher, Detlev; Schneider, Claus M.; Voigtländer, Bert

    2017-06-01

    Three-dimensional topological insulators host surface states with linear dispersion, which manifest as a Dirac cone. Nanoscale transport measurements provide direct access to the transport properties of the Dirac cone in real space and allow the detailed investigation of charge carrier scattering. Here we use scanning tunnelling potentiometry to analyse the resistance of different kinds of defects at the surface of a (Bi0.53Sb0.47)2Te3 topological insulator thin film. We find the largest localized voltage drop to be located at domain boundaries in the topological insulator film, with a resistivity about four times higher than that of a step edge. Furthermore, we resolve resistivity dipoles located around nanoscale voids in the sample surface. The influence of such defects on the resistance of the topological surface state is analysed by means of a resistor network model. The effect resulting from the voids is found to be small compared with the other defects.

  15. Application of Three Electrical Resistivity Arrays to Evaluate ...

    African Journals Online (AJOL)

    dipole, and Pole-dipole) based on their resolution capacity to delineate fractured zones at Apatara Farm in Iwo, Osun State, Nigeria. Theoretical apparent resistivity data were computed for each model and contaminated with 5% Gaussian noise as ...

  16. Transcriptome analysis of resistant and susceptible tobacco (Nicotiana tabacum) in response to root-knot nematode Meloidogyne incognita infection.

    Science.gov (United States)

    Xing, Xuexia; Li, Xiaohui; Zhang, Mingzhen; Wang, Yuan; Liu, Bingyang; Xi, Qiliang; Zhao, Ke; Wu, Yunjie; Yang, Tiezhao

    2017-01-22

    The root-knot nematode (RKN) Meloidogyne incognita reproduces on the roots of tobacco (Nicotiana tabacum), damaging crops, reducing crop yield, and causing economic losses annually. The development of resistant genotypes is an alternative strategy to effectively control these losses. However, the molecular mechanism responsible for host pathogenesis and defense responses in tobacco specifically against RKNs remain poorly understood. Here, root transcriptome analysis of resistant (Yuyan12) and susceptible (Changbohuang) tobacco varieties infected with RKNs was performed. Moreover, 2623 and 545 differentially expressed genes (DEGs) in RKN-infected roots were observed in Yuyan12 and Changbohuang, respectively, compared to those in non-infected roots, including 289 DEGs commonly expressed in the two genotypes. Among these DEGs, genes encoding cell wall modifying proteins, auxin-related proteins, the ROS scavenging system, and transcription factors involved in various biological and physiochemical processes were significantly expressed in both the resistant and susceptible genotypes. This work is thus the first report on the relationships in the RKN-tobacco interaction using transcriptome analysis, and the results provide important information on the mechanism of RKN resistance in tobacco. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Efficacy of combined therapy with amantadine, oseltamivir, and ribavirin in vivo against susceptible and amantadine-resistant influenza A viruses.

    Science.gov (United States)

    Nguyen, Jack T; Smee, Donald F; Barnard, Dale L; Julander, Justin G; Gross, Matthew; de Jong, Menno D; Went, Gregory T

    2012-01-01

    The limited efficacy of existing antiviral therapies for influenza--coupled with widespread baseline antiviral resistance--highlights the urgent need for more effective therapy. We describe a triple combination antiviral drug (TCAD) regimen composed of amantadine, oseltamivir, and ribavirin that is highly efficacious at reducing mortality and weight loss in mouse models of influenza infection. TCAD therapy was superior to dual and single drug regimens in mice infected with drug-susceptible, low pathogenic A/H5N1 (A/Duck/MN/1525/81) and amantadine-resistant 2009 A/H1N1 influenza (A/California/04/09). Treatment with TCAD afforded >90% survival in mice infected with both viruses, whereas treatment with dual and single drug regimens resulted in 0% to 60% survival. Importantly, amantadine had no activity as monotherapy against the amantadine-resistant virus, but demonstrated dose-dependent protection in combination with oseltamivir and ribavirin, indicative that amantadine's activity had been restored in the context of TCAD therapy. Furthermore, TCAD therapy provided survival benefit when treatment was delayed until 72 hours post-infection, whereas oseltamivir monotherapy was not protective after 24 hours post-infection. These findings demonstrate in vivo efficacy of TCAD therapy and confirm previous reports of the synergy and broad spectrum activity of TCAD therapy against susceptible and resistant influenza strains in vitro.

  18. Efficacy of combined therapy with amantadine, oseltamivir, and ribavirin in vivo against susceptible and amantadine-resistant influenza A viruses.

    Directory of Open Access Journals (Sweden)

    Jack T Nguyen

    Full Text Available The limited efficacy of existing antiviral therapies for influenza--coupled with widespread baseline antiviral resistance--highlights the urgent need for more effective therapy. We describe a triple combination antiviral drug (TCAD regimen composed of amantadine, oseltamivir, and ribavirin that is highly efficacious at reducing mortality and weight loss in mouse models of influenza infection. TCAD therapy was superior to dual and single drug regimens in mice infected with drug-susceptible, low pathogenic A/H5N1 (A/Duck/MN/1525/81 and amantadine-resistant 2009 A/H1N1 influenza (A/California/04/09. Treatment with TCAD afforded >90% survival in mice infected with both viruses, whereas treatment with dual and single drug regimens resulted in 0% to 60% survival. Importantly, amantadine had no activity as monotherapy against the amantadine-resistant virus, but demonstrated dose-dependent protection in combination with oseltamivir and ribavirin, indicative that amantadine's activity had been restored in the context of TCAD therapy. Furthermore, TCAD therapy provided survival benefit when treatment was delayed until 72 hours post-infection, whereas oseltamivir monotherapy was not protective after 24 hours post-infection. These findings demonstrate in vivo efficacy of TCAD therapy and confirm previous reports of the synergy and broad spectrum activity of TCAD therapy against susceptible and resistant influenza strains in vitro.

  19. The Janus face of reactive oxygen species in resistance and susceptibility of plants to necrotrophic and biotrophic pathogens.

    Science.gov (United States)

    Barna, B; Fodor, J; Harrach, B D; Pogány, M; Király, Z

    2012-10-01

    Plant pathogens can be divided into biotrophs and necrotrophs according to their different life styles; biotrophs prefer living, while necrotrophs prefer dead cells for nutritional purposes. Therefore tissue necrosis caused by reactive oxygen species (ROS) during pathogen infection increases host susceptibility to necrotrophic, but resistance to biotrophic pathogen. Consequently, elevation of antioxidant capacity of plants enhances their tolerance to development of necroses caused by necrotrophic pathogens. Plant hormones can strongly influence induction of ROS and antioxidants, thereby influencing susceptibility or resistance of plants to pathogens. Pathogen-induced ROS themselves are considered as signaling molecules. Generally, salicylic acid (SA) signaling induces defense against biotrophic pathogens, whereas jasmonic acid (JA) against necrotrophic pathogens. Furthermore pathogens can modify plant's defense signaling network for their own benefit by changing phytohormone homeostasis. On the other hand, ROS are harmful also to the pathogens, consequently they try to defend themselves by elevating antioxidant activity and secreting ROS scavengers in the infected tissue. The Janus face nature of ROS and plant cell death on biotrophic and on necrotrophic pathogens is also supported by the experiments with BAX inhibitor-1 and the mlo mutation of Mlo gene in barley. It was found that ROS and elevated plant antioxidant activity play an important role in systemic acquired resistance (SAR) and induced systemic resistance (ISR), as well as in mycorrhiza induced abiotic and biotic stress tolerance of plants. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  20. High susceptibility and low resistance allele frequency of Chrysodeixis includens (Lepidoptera: Noctuidae) field populations to Cry1Ac in Brazil.

    Science.gov (United States)

    Yano, Silvia Ac; Specht, Alexandre; Moscardi, Flávio; Carvalho, Renato A; Dourado, Patrick M; Martinelli, Samuel; Head, Graham P; Sosa-Gómez, Daniel R

    2016-08-01

    The soybean looper (SBL), Chrysodeixis includens (Walker), is one of the most important soybean pests in Brazil. MON 87701 × MON 89788 soybean expressing Cry1Ac has been recently deployed in Brazil, providing high levels of control against the primary lepidopteran pests. To support insect resistance management (IRM) programmes, the baseline susceptibility of SBL to Cry1Ac was assessed, and the resistance allele frequency was estimated on the basis of an F2 screen. The toxicity (LC50 ) of Cry1Ac ranged from 0.39 to 2.01 µg mL(-1) diet among all SBL field populations collected from crop seasons 2008/09 to 2012/13, which indicated approximately fivefold variation. Cry1Ac diagnostic concentrations of 5.6 and 18 µg mL(-1) diet were established for monitoring purposes, and no shift in mortality was observed. A total of 626 F2 family lines derived from SBL collected from locations across Brazil during crop season 2014/15 were screened for the presence of Cry1Ac resistance alleles. None of the 626 families survived on MON 87701 × MON 89788 soybean leaf tissue (joint frequency 0.0004). SBL showed high susceptibility and low resistance allele frequency to Cry1Ac across the main soybean-producing regions in Brazil. These findings meet important criteria for effective IRM strategy. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  1. Resistance evaluation of Chinese wild Vitis genotypes against Botrytis cinerea and different responses of resistant and susceptible hosts to the infection

    Science.gov (United States)

    Wan, Ran; Hou, Xiaoqing; Wang, Xianhang; Qu, Jingwu; Singer, Stacy D.; Wang, Yuejin; Wang, Xiping

    2015-01-01

    The necrotrophic fungus Botrytis cinerea is a major threat to grapevine cultivation worldwide. A screen of 41 Vitis genotypes for leaf resistance to B. cinerea suggested species independent variation and revealed 18 resistant Chinese wild Vitis genotypes, while most investigated V. vinifera, or its hybrids, were susceptible. A particularly resistant Chinese wild Vitis, “Pingli-5” (V. sp. [Qinling grape]) and a very susceptible V. vinifera cultivar, “Red Globe” were selected for further study. Microscopic analysis demonstrated that B. cinerea growth was limited during early infection on “Pingli-5” before 24 h post-inoculation (hpi) but not on Red Globe. It was found that reactive oxygen species (ROS) and antioxidative system were associated with fungal growth. O2- accumulated similarly in B. cinerea 4 hpi on both Vitis genotypes. Lower levels of O2- (not H2O2) were detected 4 hpi and ROS (H2O2 and O2-) accumulation from 8 hpi onwards was also lower in “Pingli-5” leaves than in “Red Globe” leaves. B. cinerea triggered sustained ROS production in “Red Globe” but not in “Pingli-5” with subsequent infection progresses. Red Globe displayed little change in antioxidative activities in response to B. cinerea infection, instead, antioxidative activities were highly and timely elevated in resistant “Pingli-5” which correlated with its minimal ROS increases and its high resistance. These findings not only enhance our understanding of the resistance of Chinese wild Vitis species to B. cinerea, but also lay the foundation for breeding B. cinerea resistant grapes in the future. PMID:26579134

  2. Thermal treatment of low permeability soils using electrical resistance heating

    Energy Technology Data Exchange (ETDEWEB)

    Udell, K.S. [Univ. of California, Berkeley, CA (United States)

    1996-08-01

    The acceleration of recovery rates of second phase liquid contaminants from the subsurface during gas or water pumping operations is realized by increasing the soil and ground water temperature. Electrical heating with AC current is one method of increasing the soil and groundwater temperature and has particular applicability to low permeability soils. Several mechanisms have been identified that account for the enhanced removal of the contaminants during electrical heating. These are vaporization of liquid contaminants with low boiling points, temperature-enhanced evaporation rates of semi-volatile components, and removal of residual contaminants by the boiling of residual water. Field scale studies of electrical heating and fluid extraction show the effectiveness of this technique and its applicability to contaminants found both above and below the water table and within low permeability soils. 10 refs., 8 figs.

  3. Studies of electrical properties of low-resistivity sandstones based on digital rock technology

    Science.gov (United States)

    Yan, Weichao; Sun, Jianmeng; Zhang, Jinyan; Yuan, Weiguo; Zhang, Li; Cui, Likai; Dong, Huaimin

    2018-02-01

    Electrical properties are important parameters to quantitatively calculate water saturation in oil and gas reservoirs by well logging interpretation. It is usual that oil layers show high resistivity responses, while water layers show low-resistivity responses. However, there are low-resistivity oil zones that exist in many oilfields around the world, leading to difficulties for reservoir evaluation. In our research, we used digital rock technology to study different internal and external factors to account for low rock resistivity responses in oil layers. We first constructed three-dimensional digital rock models with five components based on micro-computed tomography technology and x-ray diffraction experimental results, and then oil and water distributions in pores were determined by the pore morphology method. When the resistivity of each component was assigned, rock resistivities were calculated by using the finite element method. We collected 20 sandstone samples to prove the effectiveness of our numerical simulation methods. Based on the control variate method, we studied the effects of different factors on the resistivity indexes and rock resistivities. After sensitivity analyses, we found the main factors which caused low rock resistivities in oil layers. For unfractured rocks, influential factors arranged in descending order of importance were porosity, clay content, temperature, water salinity, heavy mineral, clay type and wettability. In addition, we found that the resistivity index could not provide enough information to identify a low-resistivity oil zone by using laboratory rock–electric experimental results. These results can not only expand our understandings of the electrical properties of low-resistivity rocks from oil layers, but also help identify low-resistivity oil zones better.

  4. Transcriptome profiling of resistant and susceptible Cavendish banana roots following inoculation with Fusarium oxysporum f. sp. cubense tropical race 4

    Directory of Open Access Journals (Sweden)

    Li Chun-yu

    2012-08-01

    Full Text Available Abstract Background Fusarium wilt, caused by the fungal pathogen Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4, is considered the most lethal disease of Cavendish bananas in the world. The disease can be managed in the field by planting resistant Cavendish plants generated by somaclonal variation. However, little information is available on the genetic basis of plant resistance to Foc TR4. To a better understand the defense response of resistant banana plants to the Fusarium wilt pathogen, the transcriptome profiles in roots of resistant and susceptible Cavendish banana challenged with Foc TR4 were compared. Results RNA-seq analysis generated more than 103 million 90-bp clean pair end (PE reads, which were assembled into 88,161 unigenes (mean size = 554 bp. Based on sequence similarity searches, 61,706 (69.99% genes were identified, among which 21,273 and 50,410 unigenes were assigned to gene ontology (GO categories and clusters of orthologous groups (COG, respectively. Searches in the Kyoto Encyclopedia of Genes and Genomes Pathway database (KEGG mapped 33,243 (37.71% unigenes to 119 KEGG pathways. A total of 5,008 genes were assigned to plant-pathogen interactions, including disease defense and signal transduction. Digital gene expression (DGE analysis revealed large differences in the transcriptome profiles of the Foc TR4-resistant somaclonal variant and its susceptible wild-type. Expression patterns of genes involved in pathogen-associated molecular pattern (PAMP recognition, activation of effector-triggered immunity (ETI, ion influx, and biosynthesis of hormones as well as pathogenesis-related (PR genes, transcription factors, signaling/regulatory genes, cell wall modification genes and genes with other functions were analyzed and compared. The results indicated that basal defense mechanisms are involved in the recognition of PAMPs, and that high levels of defense-related transcripts may contribute to Foc TR4 resistance in

  5. Influence of Dry Cleaning on the Electrical Resistance of Screen Printed Conductors on Textiles

    Directory of Open Access Journals (Sweden)

    Kazani Ilda

    2016-09-01

    Full Text Available Electrically conducting inks were screen printed on various textile substrates. The samples were dry cleaned with the usual chemicals in order to investigate the influence of the mechanical treatment on the electrical conductivity. It was found that dry cleaning has a tremendous influence on this electrical conductivity. For several samples, it is observed that the electrical resistance increases with the square of the number of dry cleaning cycles. In order to explain this observation a theoretical model and a numerical simulation have been carried out, by assuming that dry cleaning cycles introduce a crack in the conducting layer. The theoretical analysis and the numerical analysis both confirmed the experimental observations.

  6. Occurrence of paracrystalloids and their particles in resistant and susceptible carnation plants infected with Fusarium oxysporum f.sp dianthi race 2

    NARCIS (Netherlands)

    Ouellette, G.B.; Rioux, D.; Simard, M.; Baayen, R.P.

    2004-01-01

    Uncommon, opaque particles (of approximately 20-22 nm, referred to as OP), aggregating into paracrystalloids occurred only next to colonized cells in carnation plants of either a susceptible or resistant cultivar (cv.) infected with Fusarium oxysporum f.sp. dianthi. In the susceptible plant, those

  7. Discrepant susceptibility to gentamicin despite amikacin resistance in Klebsiella pneumoniae by VITEK 2 represents false susceptibility associated with the armA 16S rRNA methylase gene.

    Science.gov (United States)

    Ko, Jae-Hoon; Baek, Jin Yang; Peck, Kyong Ran; Cho, Sun Young; Ha, Young Eun; Kim, So Hyun; Huh, Hee Jae; Lee, Nam Yong; Kang, Cheol-In; Chung, Doo Ryeon; Song, Jae-Hoon

    2017-10-01

    Because we experienced gentamicin failure in Klebsiella pneumoniae bacteraemia that was susceptible to gentamicin despite amikacin resistance, as determined by VITEK 2, we evaluated the true susceptibility and mechanism of resistance. We screened 2818 K. pneumoniae isolates during a 1-year period at a university hospital and reviewed anti-microbial susceptibility reports using the VITEK 2 system. The minimum inhibitory concentration was substantiated by broth microdilution (BMD), and the presence of 16S rRNA methylase genes and aminoglycoside-modifying enzymes was also investigated. A total of 131 amikacin-resistant isolates from 19 patients were gentamicin non-resistant according to the VITEK 2 system. Among these, we were able to collect isolates from 12 patients (63.2 %), and a single isolate from each patient was tested. Eleven of the gentamicin non-resistant isolates (91.7 %) showed high-level resistance to both amikacin and gentamicin by BMD in association with the armA gene. Gentamicin is not an adequate treatment option for amikacin-resistant K. pneumoniae, even if VITEK 2 reports susceptibility.

  8. Electrical Resistivity Measurement of Cu and Zn on the Pressure-Dependent Melting Boundary

    Science.gov (United States)

    Secco, R. A.; Ezenwa, I.; Yong, W.

    2016-12-01

    Understanding how the core cools through heat conduction and modelling the geodynamo requires knowledge of the thermal and electrical conductivity of solid and liquid Fe and its relevant alloys at high pressures. It has been proposed that electrical resistivity of a pure metal is constant along its P-dependent melting boundary (Stacey and Anderson, PEPI, 2001). If confirmed, this invariant behavior could serve as a practical tool for low P studies to assess electrical resistivity of Earth's core. Since Earth's inner core boundary (ICB) is a melting boundary of mainly Fe, measurements of electrical resistivity of Fe at the melting boundary, under any P, would serve as a proxy for the resistivity at the ICB. A revised treatment (Stacey and Loper, PEPI, 2007) accounted for s-d scattering in transition metals with unfilled d-bands and limited the proposal to metals with electrons of the same type in filled d-band metals. To test this proposal, we made high P, T measurements of electrical resistivity of d-band filled Cu and Zn in solid and liquid states. Experiments were carried out in a 1000 ton cubic anvil press up to 5 GPa and 300K above melting temperatures. Two thermocouples placed at opposite ends of the wire sample served as T probes as well as 4-wire resistance electrodes in a switched circuit. A polarity switch was used to remove any bias voltage measurement using thermocouple legs. Electron microprobe analyses were used to check the compositions of the recovered samples. The expected resistivity decrease with P and increase with T were found and comparisons with 1atm data are in very good agreement. Within the error of measurement, the resistivity values of Cu decrease along the melting boundary while Zn appears to support the hypothesis of constant resistivity along the melting boundary.

  9. Standardized interpretation of antibiotic susceptibility testing and resistance genotyping for Mycobacterium abscessus with regard to subspecies and erm41 sequevar.

    Science.gov (United States)

    Mougari, Faiza; Amarsy, Rishma; Veziris, Nicolas; Bastian, Sylvaine; Brossier, Florence; Berçot, Béatrice; Raskine, Laurent; Cambau, Emmanuelle

    2016-08-01

    The objective of this study was to provide standardized antibiotic susceptibility testing (AST) for Mycobacterium abscessus with regard to subspecies. One hundred and sixty-five clinical isolates were tested for susceptibility to 15 antibiotics using a commercial microdilution method, at two reading times: (i) early reading time (ERT), when the growth control was first positive; and (ii) late reading time (LRT), of 14 days, for detecting inducible resistance. In addition, genes or mutations involved in resistance were studied [erm(41), rrl and rrs]. Three patterns were observed for clarithromycin: (i) MIC >16 mg/L at ERT (median 5 days) for 15 isolates [10 subsp. abscessus erm(41) sequevar T28, 3 subsp. bolletii and 2 subsp. massiliense] among which 9 harboured an a2058g/c rrl mutation; (ii) MIC ≤16 mg/L at ERT, but >16 mg/L at LRT, for 106 isolates [84 abscessus erm(41) T28 and 22 bolletii] showing intrinsic inducible resistance; and (iii) MIC ≤4 mg/L at ERT and LRT for 44 isolates [18 abscessus erm(41) C28 and 26 massiliense]. Amikacin MIC was >64 mg/L for eight isolates [five abscessus erm(41) T28, two massiliense and one bolletii] among which seven harboured the a1408g rrs mutation, but ≤64 mg/L for the remaining isolates without mutation. For the other antibiotics, only one WT pattern was observed, with cefoxitin, tigecycline and linezolid showing MIC values compatible with susceptibility. Standard AST can predict clarithromycin and amikacin resistance using interpretation rules with regard to subspecies. For other antibiotics, since only one pattern is observed, there is no need for systematic phenotypic or genotypic testing. © 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.

  10. Statistical analysis of electrical resistivity as a tool for estimating cement type of 12-year-old concrete specimens

    NARCIS (Netherlands)

    Polder, R.B.; Morales-Napoles, O.; Pacheco, J.

    2012-01-01

    Statistical tests on values of concrete resistivity can be used as a fast tool for estimating the cement type of old concrete. Electrical resistivity of concrete is a material property that describes the electrical resistance of concrete in a unit cell. Influences of binder type, water-to-binder

  11. Concurrent outbreak of multidrug-resistant and susceptible subclones of Acinetobacter baumannii affecting different wards of a single hospital.

    Science.gov (United States)

    Maslow, Joel N; Glaze, Thomas; Adams, Pamela; Lataillade, Max

    2005-01-01

    Acinetobacter baumannii has emerged as an opportunistic pathogen among acutely ill patients, especially those with thermal injury. A prospective 8-month study was conducted to describe the clinical and molecular epidemiology of multidrug-resistant A. baumannii affecting a single hospital. Univariate analysis comparing SmaI macrorestriction patterns of A. baumannii generated by pulsed-field gel electrophoresis (PFGE) versus clinical and demographic risk factors. A total of 200 isolates from 76 patients were collected, of which 185 isolates from 76 patients were analyzed by PFGE. A total of 17 distinct PFGE clonal types were identified. One clonal type (strain A) represented 129 isolates from 49 patients. A group of related clonal types (strain A variants) were identified as 40 isolates from 20 patients. The only risk factor other than geographic location associated with the presence of strain A was prior treatment with antibiotics active against gram-negative bacteria (P = .0015). The two clonal types differed in antibiotic resistance profiles: 25% of strain A isolates, the dominant strain in the burn unit, were susceptible to at least one antibiotic tested. In contrast, approximately 80% of the other strain types were susceptible to at least one antibiotic and were cultured from patients admitted elsewhere in the hospital. No combination of antibiotics was observed to yield additive or synergistic activity. Clonally related strains of Acinetobacter that differ in susceptibility patterns may coexist within a single hospital, dependent on the selective pressure related to antibiotic exposure.

  12. Mutations conferring resistance to viral DNA polymerase inhibitors in camelpox virus give different drug-susceptibility profiles in vaccinia virus.

    Science.gov (United States)

    Duraffour, Sophie; Andrei, Graciela; Topalis, Dimitri; Krečmerová, Marcela; Crance, Jean-Marc; Garin, Daniel; Snoeck, Robert

    2012-07-01

    Cidofovir or (S)-HPMPC is one of the three antiviral drugs that might be used for the treatment of orthopoxvirus infections. (S)-HPMPC and its 2,6-diaminopurine counterpart, (S)-HPMPDAP, have been described to select, in vitro, for drug resistance mutations in the viral DNA polymerase (E9L) gene of vaccinia virus (VACV). Here, to extend our knowledge of drug resistance development among orthopoxviruses, we selected, in vitro, camelpox viruses (CMLV) resistant to (S)-HPMPDAP and identified a single amino acid change, T831I, and a double mutation, A314V+A684V, within E9L. The production of recombinant CMLV and VACV carrying these amino acid substitutions (T831I, A314V, or A314V+A684V) demonstrated clearly their involvement in conferring reduced sensitivity to viral DNA polymerase inhibitors, including (S)-HPMPDAP. Both CMLV and VACV harboring the A314V change showed comparable drug-susceptibility profiles to various antivirals and similar impairments in viral growth. In contrast, the single change T831I and the double change A314V+A684V in VACV were responsible for increased levels of drug resistance and for cross-resistance to viral DNA polymerase antivirals that were not observed with their CMLV counterparts. Each amino acid change accounted for an attenuated phenotype of VACV in vivo. Modeling of E9L suggested that the T→I change at position 831 might abolish hydrogen bonds between E9L and the DNA backbone and have a direct impact on the incorporation of the acyclic nucleoside phosphonates. Our findings demonstrate that drug-resistance development in two related orthopoxvirus species may impact drug-susceptibility profiles and viral fitness differently.

  13. Effects of Insecticides on the Fluidity of Mitochondrial Membranes of the Diamondback Moth, Plutella xylostella, Resistant and Susceptible to Avermectin

    Science.gov (United States)

    Hu, J.; Liang, P.; Shi, X.; Gao, X.

    2008-01-01

    The effects of various insecticides on the fluidity of mitochondrial membranes and cross-resistance were investigated in the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) using strains that were both resistant and susceptible to avermectin. The resistant strain of P. xylostella, AV-R, developed 1078-fold resistance to avermetins with a high level of cross-resistance to the analogs of avermectins, ivermectin and emamectin benzoate. It had more than 1000 times greater resistance when compared with the avermectin-susceptible strain, XH-S. Mitochondrial membrane fluidity was measured by detecting fluorescence polarization using DPH (1,6-Diphenyl -1,3,5-hexatriene) as the fluorescence probe. Abamectin, emamectin benzoate, ivermectin, cypermethrin and fenvalerate decreased the fluidity of mitochondrial membranes in the XH-S strain at 25°C. However, fipronil and acephate did not change the fluidity of mitochondrial membrane when the concentration of these insecticides was 1×10-4 mol/L. Membrane fluidity increased as the temperature increased. The thermotropic effect on the polarization value of DPH increased as the insecticide concentration was increased. There was a significant difference of mitochondrial membrane fluidity between both XH-S and AV-R when temperature was less than 25°C and no difference was observed when the temperature was more than 25°C. The low-dose abamectin (0.11 mg/L) in vivo treatment caused a significant change of membrane fluidity in the XH-S strain and no change in the AV-R strain. However, a high-dose abamectin (11.86 mg/L) resulted in 100% mortality of the XH-S strain. In vivo treatment may cause a significant change of membrane fluidity in the AV-R strain PMID:20345311

  14. Fluoroquinolone Resistance Mechanisms and population structure of Enterobacter cloacae non-susceptible to Ertapenem in North-Eastern France.

    Directory of Open Access Journals (Sweden)

    Thomas eGuillard

    2015-10-01

    Full Text Available Fluoroquinolone (FQ agents are a potential resort to treat infection due to Enterobacteriaceae producing extended spectrum β-lactamase and susceptible to FQ. In a context of increase of non-susceptibility to carbapenems among Enterobacteriaceae, we characterized FQ resistance mechanisms in 75 Enterobacter cloacae isolates non-susceptible to ertapenem in North-Eastern France in 2012 and describe the population structure by pulsed field gel electrophoresis (PFGE and multilocus sequence typing (MLST.Among them, 14.7% (12/75 carried a carbapenemase-encoding gene. Except one isolate producing VIM-1, the carbapenemase-producing isolates carried the well-known IncL/M pOXA48a plasmid. Most of the isolates (59/75 harbored at least a FQ-R determinant. qnr genes were predominant (40%, 30/75. The MLST study revealed that E. cloacae isolates’ clonality was wide (24 different STs. The more widespread STs were ST74, ST101, ST110, ST114 and ST133. Carbapenem MICs were higher for E. cloacae ST74 than for other E. cloacae isolates. PMQR determinants were more often observed in E. cloacae ST74 isolates. These findings showed that (i pOXA-48a is spreading in North-Eastern France, (ii qnr is preponderant in E. cloacae, (iii E. cloacae comprised a large amount of lineages spreading in North-Eastern France and (iv FQ as an alternative to β-lactams to treat ertapenem non-susceptible Enterobacteriaceae are compromised.

  15. Loss of Sex and Age Driven Differences in the Gut Microbiome Characterize Arthritis-Susceptible *0401 Mice but Not Arthritis-Resistant *0402 Mice

    OpenAIRE

    Andres Gomez; David Luckey; Yeoman, Carl J.; Marietta, Eric V; Margret E Berg Miller; Joseph A Murray; White, Bryan A.; Veena Taneja

    2012-01-01

    BACKGROUND: HLA-DRB1 0401 is associated with susceptibility, while HLA-DRB1 0402 is associated with resistance to developing rheumatoid arthritis (RA) and collagen-induced arthritis in humans and transgenic mice respectively. The influence of gut-joint axis has been suggested in RA, though not yet proven. METHODOLOGY/PRINCIPAL FINDINGS: We have used HLA transgenic mice carrying arthritis susceptible and -resistant HLA-DR genes to explore if genetic factors and their interaction with gut flora...

  16. ANALYSIS OF EXCESSIVE HEATING ON THE THERMAL AND ELECTRICAL RESISTANCE OF A POLYMER ELECTROLYTE

    Directory of Open Access Journals (Sweden)

    R. Atan

    2012-06-01

    Full Text Available The performance on a polymer electrolyte membrane (PEM fuel cell is evaluated based on the relationship of thermal and electrical resistances to its electrical and thermal power output. An analytical method by which the electrical resistance is evaluated based on the polarisation curve and the thermal resistance from the mass balance, was applied to a 72-cell PEM fuel cell assembly. In order to evaluate the effect of resistances at elevated stack temperatures, the cooling system was operated at half of its maximum cooling effectiveness. The increase in current and resistance due to a unit change in temperature at a particular density was evaluated and it was found that the stack has a ratio of thermal resistance rise to current rise of 1.7, or equal to 0.00584 A/W of current increase per stack heat increase. These values suggest that the internal resistance of the stack components, most probably the electrode assemblies, are very high, which should be addressed in order to obtain lower resistances to current flow.

  17. Electrical Resistivity as an Indicator of Saturation in Fractured Geothermal Reservoir Rocks: Experimental Data and Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Detwiler, R L; Roberts, J J

    2003-06-23

    The electrical resistivity of rock cores under conditions representative of geothermal reservoirs is strongly influenced by the state and phase (liquid/vapor) of the pore fluid. In fractured samples, phase change (vaporization/condensation) can result in resistivity changes that are more than an order of magnitude greater than those measured in intact samples. These results suggest that electrical resistivity monitoring of geothermal reservoirs may provide a useful tool for remotely detecting the movement of water and steam within fractures, the development and evolution of fracture systems and the formation of steam caps. We measured the electrical resistivity of cores of welded tuff containing fractures of various geometries to investigate the resistivity contrast caused by active boiling and to determine the effects of variable fracture dimensions and surface area on water extraction from the matrix. We then used the Nonisothermal Unsaturated Flow and Transport model (NUFT) (Nitao, 1998) to simulate the propagation of boiling fronts through the samples. The simulated saturation profiles combined with previously reported measurements of resistivity-saturation curves allow us to estimate the evolution of the sample resistivity as the boiling front propagates into the rock matrix. These simulations provide qualitative agreement with experimental measurements suggesting that our modeling approach may be used to estimate resistivity changes induced by boiling in more complex systems.

  18. A combination of electrical resistivity and cone penetration test ...

    African Journals Online (AJOL)

    Geophysical and geotechnical methods were used with the aim of characterizing the subsurface in order to identify the cause of differential settlement of the structures in the Adeniji Adele Low Cost Housing Estate, Lagos Island, Lagos State. Twelve (12) Schlumberger Vertical Electrical Soundings (VES), five Wenner 2D ...

  19. Antimosquito property of Petroselinum crispum (Umbellifereae) against the pyrethroid resistant and susceptible strains of Aedes aegypti (Diptera: Culicidae).

    Science.gov (United States)

    Intirach, J; Junkum, A; Lumjuan, N; Chaithong, U; Jitpakdi, A; Riyong, D; Wannasan, A; Champakaew, D; Muangmoon, R; Chansang, A; Pitasawat, B

    2016-12-01

    The increasing and widespread resistance to conventional synthetic insecticides in vector populations has underscored the urgent need to establish alternatives in the mosquito management system. This study was carried out with the aim to investigate the antimosquito property, larvicidal and adulticidal potential, of plant products against both the pyrethroid-susceptible and resistant strains of Aedes aegypti. Seventeen plant products, including essential oils and ethanolic extracts, were obtained by steam distillation and extraction with 95 % ethanol, respectively. Their larvicidal activity was screened, using World Health Organization (WHO) procedures against A. aegypti, Muang Chiang Mai-susceptible (MCM-S) strain. The most effective product was a candidate for investigating larvicidal and adulticidal potential against three laboratory strains of A. aegypti, comprising MCM-S, Pang Mai Dang-resistant (PMD-R), and Upakut-resistant (UPK-R). Potential toxicity of the plant candidate was compared with that of synthetic temephos, permethrin, and deltamethrin. Chemical constituents of the most effective plant product also were analyzed by gas chromatography-mass spectrometry (GC-MS). Results obtained from the preliminary screening revealed the varying larvicidal efficacy of plant-derived products against MCM-S A. aegypti, with mortality ranging from 0 to 100 %. The larvicidal activity of seven effective plant products was found to be dose dependent, with the highest efficacy established from Petroselinum crispum fruit oil, followed by oils of Foeniculum vulgare, Myristica fragrans, Limnophila aromatica, Piper sarmentosum, Curcuma longa, and M. fragrans ethanolic extract (LC50 values of 43.22, 44.84, 47.42, 47.94, 49.19, 65.51, and 75.45 ppm, respectively). Essential oil of P. crispum was then investigated further and proved to be a promising larvicide and adulticide against all strains of A. aegypti. The pyrethroid-resistant strains of both PMD-R and UPK-R A. aegypti

  20. TRIMETHOPRIM-SULFAMETHOXAZOLE RESISTANCE AND FOSFOMYCIN SUSCEPTIBILITY RATES IN UNCOMPLICATED URINARY TRACT INFECTIONS: TIME TO CHANGE THE ANTIMICROBIAL PREFERENCES.

    Science.gov (United States)

    Guneysel, Ozlem; Suman, Enes; Ozturk, Tuba Cimilli

    2016-03-01

    Urinary tract infections (UTIs) are among the most common bacterial infections in adult population. They are prevalent in all age groups both in women and men. Also, UTIs are the most frequent indication for empirical antibiotic treatment in emergency department. The aim of this study was to determine the antibiotic resistance rates in the treatment of uncomplicated UTIs. Adult patients admitted to emergency department with uncomplicated UTIs were included in this cross-sectional study. Mid-stream urine samples were obtained under sterile conditions and cultured quantitatively. After 24 hours, the samples showing 10(5) colony forming unit per milliliter (CFU/mL) were tested for antibiotic susceptibility. Resistance to fosfomycin-trometamol (FT), amoxicillin-clavulanic acid (AC), ciprofloxacin (CIP), trimethoprim-sulfamethoxazole (TMP-SMX) and cefpodoxime (CEF) was tested by Kirby-Bauer disc diffusion system. Escherichia (E.) coli accounted for the vast majority (93.4%) of the organisms isolated in the study. Among the E. coli positive patients, resistance to TMP-SMX was the most common antibiotic resistance. The E. coli species detected in our study group were least resistant to FT (2.4%). The resistance rates, especially to CEF, AC and CIP, were significantly higher in patients over 50 years of age. In conclusion, in the treatment of uncomplicated UTIs, TMP-SMX should be excluded from empirical treatment, while fosfomycin could be a viable option in all age groups.

  1. Susceptibility of populations of Banks grass mites (Acari: Tetranychidae) suspected of developing bifenthrin resistance from three maize fields.

    Science.gov (United States)

    Bynum, E D; Archer, T L

    2002-01-01

    Banks grass mite, Oligonychus pratensis (Banks), from three Texas maize fields were assayed for bifenthrin resistance following poor field control in 1995. Laboratory bioassays showed the field mites to be 3- to 23-fold more tolerant to bifenthrin than the susceptible laboratory culture. Comparison of LC50 values to assays with bifenthrin from 1985 to 1993 indicated no statistically significant changes in mite resistance. However, high LC90 values in 1995 suggest possible resistance development. The percentages of resistant mites from the three fields in 1995 were calculated to be 4.7%, 17.9%, and 30.9%. The Banks grass mite population exhibiting the highest level of tolerance to bifenthrin was further assayed to evaluate tolerance levels to other insecticides alone and in combination with synergists and insecticides. A high level of tolerance existed in the 1995 'bifenthrin-selected' Banks grass mite strain to bifenthrin, dimeothate, and amitraz. The combination of bifenthrin or dimethoate with a synergist indicated changes in the ability of the more resistant 1995 mites to detoxify insecticides. The activity of a dimethoate + bifenthrin mixture and a three way mixture of dimethoate, bifenthrin, and piperonyl butoxide caused 5- and 38-fold increase in toxicity against the more resistant Banks grass mite.

  2. Assessment of groundwater vulnerability to leachate infiltration using electrical resistivity method

    Science.gov (United States)

    Mosuro, G. O.; Omosanya, K. O.; Bayewu, O. O.; Oloruntola, M. O.; Laniyan, T. A.; Atobi, O.; Okubena, M.; Popoola, E.; Adekoya, F.

    2017-09-01

    This aim of this work is to assess the degree of leachate infiltration at a dumpsite in Agbara industrial estate, Southwestern Nigeria using electrical resistivity techniques. Around the dumpsite were 45 vertical electrical sounding (VES) stations and 3 electrical resistivity tomography profiles. Current electrode spread varied from 300 to 600 m for the electrical sounding. Electrode configuration includes Schlumberger and Wenner array for sounding and profiling. The state of leachate contamination was tested using parameters such as aquifer vulnerability index, overburden protective capacity and longitudinal unit conductance (S i) derived from the apparent resistivity values. Four principal geoelectric layers inferred from the VES data include the topsoil, sand, clayey sand, and clay/shale. Resistivity values for these layers vary from 3 to 1688, 203 to 3642 123 to 388, and 67 to 2201 Ω m with corresponding thickness of 0.8-2.4, 2.5-140, 3-26 m and infinity, respectively. The leachate plume occurs at a maximum depth of 10 m on the 2-D inverse models of real electrical resistivity with an average depth of infiltration being 6 m in the study area. The correlation between longitudinal conductance and overburden protective capacity show that aquifers around the dumpsite have poor protective capacity and are vulnerable to leachate contamination. Leachate infiltration is favored by the absence of lithological barriers such as clay which in the study area are either mixed with sand or positioned away from the aquifer.

  3. Improved Geologic Interpretation of Non-invasive Electrical Resistivity Imaging from In-situ Samples

    Science.gov (United States)

    Mucelli, A.; Aborn, L.; Jacob, R.; Malusis, M.; Evans, J.

    2016-12-01

    Non-invasive geophysical techniques are useful in characterizing the subsurface geology without disturbing the environment, however, the ability to interpret the subsurface is enhanced by invasive work. Since geologic materials have electrical resistivity values it allows for a geologic interpretation to be made based on variations of electrical resistivity measured by electrical resistivity imaging (ERI). This study focuses on the pre-characterization of the geologic subsurface from ERI collected adjacent to the Montandon Marsh, a wetland located near Lewisburg, PA within the West Branch of the Susquehanna River watershed. The previous invasive data, boreholes, indicate that the subsurface consists of limestone and shale bedrock overlain with sand and gravel deposits from glacial outwash and aeolian processes. The objective is to improve our understanding of the subsurface at this long-term hydrologic research site by using excavation results, specifically observed variations in geologic materials and electrical resistivity laboratory testing of subsurface samples. The pre-excavation ERI indicated that the shallow-most geologic material had a resistivity value of 100-500 ohm-m. In comparison, the laboratory testing indicated the shallow-most material had the same range of electrical resistivity values depending on saturation levels. The ERI also showed that there was an electrically conductive material, 7 to 70 ohm-m, that was interpreted to be clay and agreed with borehole data, however, the excavation revealed that at this depth range the geologic material varied from stratified clay to clay with cobbles to weathered residual clay. Excavation revealed that the subtle variations in the electrical conductive material corresponded well with the variations in the geologic material. We will use these results to reinterpret previously collected ERI data from the entire long-term research site.

  4. Inaccuracy of routine susceptibility tests for detection of erythromycin resistance of Campylobacter jejuni and Campylobacter coli

    NARCIS (Netherlands)

    Beek, M.T.; Claas, E.C.J.; Mevius, D.J.; Pelt, van W.; Wagenaar, J.A.; Kuijper, E.J.

    2010-01-01

    In The Netherlands, both an increase in and regional differences in erythromycin resistance of Campylobacter jejuni and Campylobacter coli have been reported. To determine the accuracy of routine tests for erythromycin resistance, 48 erythromycin-resistant isolates from various laboratories that

  5. Antimicrobial susceptibility and occurrence of resistance genes among Salmonella enterica serovar Weltevreden from different countries

    DEFF Research Database (Denmark)

    Aarestrup, Frank Møller; Lertworapreecha, M.; Evans, M.C.

    2003-01-01

    and gentamicin. All nine ampicillin-resistant isolates contained a sequence similar to the bla(TEM-1b) gene, one of the eight chloramphenicol-resistant isolates a sequence similar to the catA1 gene, all three neomycin-resistant isolates a sequence similar to the aphA-2 gene, 16 (73%) of the 22 streptomycin...

  6. Emergence of pulsed electric fields resistance in Salmonella enterica serovar Typhimurium SL1344.

    Science.gov (United States)

    Sagarzazu, N; Cebrián, G; Pagán, R; Condón, S; Mañas, P

    2013-09-02

    In this investigation we selected and isolated a culture derived from Salmonella enterica serovar Typhimurium SL1344 with stable increased resistance to pulsed electric fields (PEF) after repeated rounds of PEF treatment and outgrowth of survivors. The resulting culture showed a higher resistance to PEF treatments under different treatment conditions. The acquisition of PEF resistance was only observed in stationary phase cells. The cytoplasmic membrane of the resistant variant showed a higher resilience against PEF treatments, since a lower permeabilization degree was observed after PEF treatments, in comparison to the parental strain. Resistance to PEF was also accompanied by a higher tolerance to acidic pH, hydrogen peroxide and ethanol, but not to heat. The occurrence of a PEF resistant variant in S. enterica serovar Typhimurium SL1344 emphasizes the need to further study the mechanisms of inactivation and resistance by PEF for an adequate design of safe treatments. © 2013.

  7. Laboratory and field evaluation of entomopathogenic fungi for the control of amitraz-resistant and susceptible strains of Rhipicephalus decoloratus.

    Science.gov (United States)

    Murigu, Mercy M; Nana, Paulin; Waruiru, Robert M; Nga'nga', Chege J; Ekesi, Sunday; Maniania, Nguya K

    2016-07-30

    Rhipicephalus decoloratus causes serious economic losses in cattle industry every year in East Africa. Biological control using entomopathogenic fungi is seen as a promising alternative to chemical acaricides being used for their control. The pathogenicity of Metarhizium anisopliae and of Beauveria bassiana isolates was tested in the laboratory against amitraz-resistant and amitraz-susceptible strains of R. decoloratus. Unfed larvae were sprayed with conidial suspensions of 1×10(9) conidia ml(-1). Fungal isolates were pathogenic to R. decoloratus larvae, causing mortality of between 10.0 and 100% and between 12.1 and 100% of amitraz-susceptible and amitraz-resistant strains, respectively. The LT50 values of selected fungal isolates varied between 2.6-4.2days in amitraz-susceptible strain and between 2.8-3.9days in amitraz-resistant strain. The LC50 values varied between 0.4±0.1 and 200.0±60×10(3) conidia ml(-1) and between 0.1±0.1 and 200.0±31.0×10(3) conidia ml(-1) in amitraz-susceptible and amitraz-resistant strains, respectively. Metarhizium anisopliae isolate ICIPE 7 outperformed the other isolates and was selected for compatibility study with amitraz and field trial. ICIPE 7 was compatible with amitraz. In the field, four treatments including control, ICIPE 7 alone, amitraz alone and ICIPE 7/amitraz were applied on cattle. All the treatments significantly reduced the number of ticks on all the sampling dates: day 7 (F3,8=3.917; P=0.0284), day 14 (F3,8=9.090; P=0.0275), day 21 (F3,8=37.971; P=0.0001) and day 28 (F3,8=8.170; P=0.0016) compared to the control. Results of the present study indicate that ICIPE 7 can be used for the management of amitraz-resistant strain of R. decoloratus. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

  8. Susceptibilities of beta-lactamase-producing and -nonproducing ampicillin-resistant strains of Haemophilus influenzae to ceftibuten, cefaclor, cefuroxime, cefixime, cefotaxime, and amoxicillin-clavulanic acid.

    Science.gov (United States)

    Barry, A L; Fuchs, P C; Pfaller, M A

    1993-01-01

    In in vitro studies we evaluated the susceptibilities of beta-lactamase-producing and -nonproducing, ampicillin-resistant strains of Haemophilus influenzae and compared them with those of ampicillin-susceptible strains. Ampicillin, amoxicillin-clavulanic acid, ceftibuten, cefaclor, cefuroxime, cefixime, and cefotaxime were evaluated by broth microdilution tests and disk diffusion tests. The disk diffusion tests accurately categorized beta-lactamase-producing strains and ampicillin-susceptible strains as being susceptible to the study drugs other than ampicillin. Ampicillin-resistant, beta-lactamase-nonproducing strains were relatively resistant to all seven study drugs, but the disk diffusion test did not always predict that resistance. The clinical relevance of the decreased susceptibility to various agents remains unclear, but to be conservative, all ampicillin-resistant, beta-lactamase-nonproducing strains might be assumed to be resistant to other beta-lactams. After excluding that small group of isolates, reliable susceptibility test results were obtained with lots of Haemophilus Test Medium that met quality assurance criteria. PMID:8431012

  9. INORGANIC PLUME DELINEATION USING SURFACE HIGH RESOLUTION ELECTRICAL RESISTIVITY AT THE BC CRIBS & TRENCHES SITE HANFORD

    Energy Technology Data Exchange (ETDEWEB)

    BENECKE, M.W.

    2007-05-29

    A surface resistivity survey was conducted on the Hanford Site over a waste disposal trench that received a large volume of liquid inorganic waste. The objective of the survey was to map the extent of the plume that resulted from the disposal activities approximately 50 years earlier. The survey included six resistivity transects of at least 200m, where each transect provided two-dimensional profile information of subsurface electrical properties. The results of the survey indicated that a low resistivity plume resides at a depth of approximately 25-44 m below ground surface. The target depth was calibrated with borehole data of pore-water electrical conductivity. Due to the high correlation of the pore-water electrical conductivity to nitrate concentration and the high correlation of measured apparent resistivity to pore-water electrical conductivity, inferences were made that proposed the spatial distribution of the apparent resistivity was due to the distribution of nitrate. Therefore, apparent resistivities were related to nitrate, which was subsequently rendered in three dimensions to show that the nitrate likely did not reach the water table and the bounds of the highest concentrations are directly beneath the collection of waste sites.

  10. Overexpression of the Bacillus thuringiensis (Bt) Cry2Aa2 protein in chloroplasts confers resistance to plants against susceptible and Bt-resistant insects.

    Science.gov (United States)

    Kota, M; Daniell, H; Varma, S; Garczynski, S F; Gould, F; Moar, W J

    1999-03-02

    Evolving levels of resistance in insects to the bioinsecticide Bacillus thuringiensis (Bt) can be dramatically reduced through the genetic engineering of chloroplasts in plants. When transgenic tobacco leaves expressing Cry2Aa2 protoxin in chloroplasts were fed to susceptible, Cry1A-resistant (20,000- to 40,000-fold) and Cry2Aa2-resistant (330- to 393-fold) tobacco budworm Heliothis virescens, cotton bollworm Helicoverpa zea, and the beet armyworm Spodoptera exigua, 100% mortality was observed against all insect species and strains. Cry2Aa2 was chosen for this study because of its toxicity to many economically important insect pests, relatively low levels of cross-resistance against Cry1A-resistant insects, and its expression as a protoxin instead of a toxin because of its relatively small size (65 kDa). Southern blot analysis confirmed stable integration of cry2Aa2 into all of the chloroplast genomes (5, 000-10,000 copies per cell) of transgenic plants. Transformed tobacco leaves expressed Cry2Aa2 protoxin at levels between 2% and 3% of total soluble protein, 20- to 30-fold higher levels than current commercial nuclear transgenic plants. These results suggest that plants expressing high levels of a nonhomologous Bt protein should be able to overcome or at the very least, significantly delay, broad spectrum Bt-resistance development in the field.

  11. Use of electrical resistivity technique for engineering site investigation

    African Journals Online (AJOL)

    The presence of moderately thick (1.5 – 16.5m) clay has been established in this area; therefore the use of raft foundation and/or any other foundation that is commensurate with civil engineering standard is suggested for high rise structures. Keywords: bedrock integrity, transverse unit resistance, foundation. Global Journal ...

  12. Application Of Electrical Resistivity Method In Coastal Hydro ...

    African Journals Online (AJOL)

    ... borehole data to provide information on the freshwater-saltwater interfaces, and the depths to freshwater bearing units in the coastal areas. The results indicated that re-sistivity contrasts can be adopted for economic evaluation of groundwater development in coastal areas. Journal of Applied Science and Technology Vol.

  13. On the Modeling of Electrical Effects Experienced by Space Explorers During Extra Vehicular Activities: Intracorporal Currents, Resistances, and Electric Fields

    Science.gov (United States)

    Cela, Carlos J.; Loizos, Kyle; Lazzi, Gianluca; Hamilton, Douglas; Lee, Raphael C.

    2011-01-01

    Recent research has shown that space explorers engaged in Extra Vehicular Activities (EVAs) may be exposed, under certain conditions, to undesired electrical currents. This work focuses on determining whether these undesired induced electrical currents could be responsible for involuntary neuromuscular activity in the subjects, possibly caused by either large diameter peripheral nerve activation or reflex activity from cutaneous afferent stimulation. An efficient multiresolution variant of the admittance method along with a millimeter-resolution model of a male human body were used to calculate induced electric fields, resistance between contact electrodes used to simulate the potential exposure condition, and currents induced in the human body model. Results show that, under realistic exposure conditions using a 15V source, current density magnitudes and total current injected are well above previously reported startle reaction thresholds. This indicates that, under the considered conditions, the subjects could experience involuntary motor response.

  14. Fusarium oxysporum f.sp. radicis-lycopersici induces distinct transcriptome reprogramming in resistant and susceptible isogenic tomato lines.

    Science.gov (United States)

    Manzo, Daniele; Ferriello, Francesca; Puopolo, Gerardo; Zoina, Astolfo; D'Esposito, Daniela; Tardella, Luca; Ferrarini, Alberto; Ercolano, Maria Raffaella

    2016-02-27

    Fusarium oxysporum f.sp. radicis-lycopersici (FORL) is one of the most destructive necrotrophic pathogens affecting tomato crops, causing considerable field and greenhouse yield losses. Despite such major economic impact, little is known about the molecular mechanisms regulating Fusarium oxysporum f.sp. radicis-lycopersici resistance in tomato. A transcriptomic experiment was carried out in order to investigate the main mechanisms of FORL response in resistant and susceptible isogenic tomato lines. Microarray analysis at 15 DPI (days post inoculum) revealed a distinct gene expression pattern between the two genotypes in the inoculated vs non-inoculated conditions. A model of plant response both for compatible and incompatible reactions was proposed. In particular, in the incompatible interaction an activation of defense genes related to secondary metabolite production and tryptophan metabolism was observed. Moreover, maintenance of the cell osmotic potential after the FORL challenging was mediated by a dehydration-induced protein. As for the compatible interaction, activation of an oxidative burst mediated by peroxidases and a cytochrome monooxygenase induced cell degeneration and necrosis. Our work allowed comprehensive understanding of the molecular basis of the tomato-FORL interaction. The result obtained emphasizes a different transcriptional reaction between the resistant and the susceptible genotype to the FORL challenge. Our findings could lead to the improvement in disease control strategies.

  15. Disaccharidase activity in the small intestine of susceptible and resistant mice after primary and challenge infections with Giardia muris.

    Science.gov (United States)

    Daniels, C W; Belosevic, M

    1992-04-01

    The activities of four disaccharidases were examined in resistant (C57Bl/6) and susceptible (C3H/HeN) mice during the primary infection with Giardia muris and after challenge with either trophozoite extract or cysts. Significant decreases in lactase, sucrase, trehalase, and maltase activities in C57Bl/6 mice and lactase and sucrase activities in C3H/HeN mice in the anterior 25% of the small intestine were observed on day 10 after infection. The activities of maltase, sucrase, trehalase, and lactase in the jejunum of C3H/HeN mice were significantly reduced after challenge with trophozoite extract, when compared with the uninfected or infected, but not challenged animals. Decreases in enzyme activities of C3H/HeN mice were evident as early as 12 hours after challenge with the extract. The resistant C57Bl/6 mice showed little change in disaccharidase activity after challenge with trophozoite extract. On the other hand, challenge with cysts resulted in a few decreases in disaccharidase activities in both strains of mice: C57Bl/6 mice showed decreases in the duodenum, while disaccharidases of C3H/HeN mice had lower activity more posteriorly. Thus, challenge with parasite antigen results in a more severe disaccharidase deficiency in susceptible hosts when compared with resistant ones.

  16. Structure of syncytia induced by Heterodera schachtii Schmidt in roots of susceptible and resistant radish (Raphanus sativus L., var. oleiformis

    Directory of Open Access Journals (Sweden)

    Grażyna Grymaszewska

    2014-01-01