156 research outputs found

    Identification of a multidrug efflux pump in Flavobacterium johnsoniae

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    In this study, the mechanism conferring multiple drug resistance in several strains of flavobacteria isolated from the ovarian fluids of hatchery reared 3-year old brook trout Salvelinus fontinalis was investigated. Metabolic fingerprinting and 16S rRNA gene sequences identified the isolates as Flavobacterium johnsoniae. The isolates exhibited multiple resistances to a wide range of antimicrobial classes including penicillin, cephem, monobactam, aminoglycoside, and phenicol. Although plasmids and other transposable elements containing antimicrobial resistance genes were not detected, the isolates did contain a genomic sequence for a chloramphenicol-inducible resistance-nodulation-division family multidrug efflux pump system. Efflux pumps are non-specific multidrug efflux systems. They are also a component of cell-cell communication systems, and respond specifically to cell membrane stressors such as oxidative or nitrosative stress. Understanding of efflux pump mediated antibiotic resistances will affect efficacy of clinical treatments of fishes associated with F. johnsoniae epizootics

    Antimicrobial Susceptibility Testing of Mycobacterium Tuberculosis Complex for First and Second Line Drugs by Broth Dilution in a Microtiter Plate Format

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    The rapid detection of antimicrobial resistance is important in the effort to control the increase in resistant Mycobacterium tuberculosis (Mtb). Antimicrobial susceptibility testing (AST) of Mtb has traditionally been performed by the agar method of proportion or by macrobroth testing on an instrument such as the BACTEC (Becton Dickinson, Sparks, MD), VersaTREK (TREK Diagnostics, Cleveland, OH) or BacT/ALERT (bioMérieux, Hazelwood, MO). The agar proportion method, while considered the “gold” standard of AST, is labor intensive and requires calculation of resistance by performing colony counts on drug-containing agar as compared to drug-free agar. If there is ≥1% growth on the drug-containing medium as compared to drug-free medium, the organism is considered resistant to that drug. The macrobroth methods require instrumentation and test break point ("critical") drug concentrations for the first line drugs (isoniazid, ethambutol, rifampin, and pyrazinamide). The method described here is commercially available in a 96 well microtiter plate format [MYCOTB (TREK Diagnostics)] and contains increasing concentrations of 12 antimicrobials used for treatment of tuberculosis including both first (isoniazid, rifampin, ethambutol) and second line drugs (amikacin, cycloserine, ethionamide, kanamycin, moxifloxacin, ofloxacin, para-aminosalicylic acid, rifabutin, and streptomycin). Pyrazinamide, a first line drug, is not included in the microtiter plate due to its need for acidic test conditions. Advantages of the microtiter system include both ease of set up and faster turn around time (14 days) compared with traditional agar proportion (21 days). In addition, the plate can be set up from inoculum prepared using either broth or solid medium. Since the microtiter plate format is new and since Mtb presents unique safety challenges in the laboratory, this protocol will describe how to safely setup, incubate and read the microtiter plate

    Benzylic C-H functionalisation by [Et3SiH + KOtBu] leads to radical rearrangements in o-tolylaryl ethers, amines

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    Reaction of Et 3SiH+KO tBu with diaryl ethers, sulfides and amines that feature an ortho alkyl group leads to rearrangement products. The rearrangements arise from formation of benzyl radicals, likely formed through hydrogen atom abstraction by triethylsilyl radicals. The rearrangements involve cyclisation of the benzyl radical onto the partner arene, which, from computation, is the rate determining step. In the case of diaryl ethers, Truce-Smiles rearrangements arise from radical cyclisations to form 5-membered rings, but for diarylamines, cyclisations to form dihydroacridines are observed. (Figure presented.)

    Transforming embodied experiences of academic conferences through creative practice : Participating in an instant choir at the nordic geographers’ meeting in 2019

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    Author's accepted version (postprint).This is an Accepted Manuscript of an article published by Sage in Cultural Geographies on 18/08/2021.Available online: https://journals.sagepub.com/doi/pdf/10.1177/14744740211039831acceptedVersio

    Et3SiH + KOtBu provide multiple reactive intermediates that compete in the reactions and rearrangements of benzylnitriles and indolenines

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    The combination of potassium tert-butoxide and triethylsilane is unusual because it generates multiple different types of reactive intermediates simultaneously that provide access to (i) silyl radical reactions, (ii) hydrogen atom transfer reactions to closed shell molecules and to radicals, (iii) electron transfer reductions and (iv) hydride ion chemistry, giving scope for unprecedented outcomes. Until now, reactions with this reagent pair have generally been explained by reference to one of the intermediates, but we now highlight the interplay and competition between them

    Conventional and microwave-assisted pyrolysis of biomass under different heating rates

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    Biomass was subjected to conventional and microwave pyrolysis, to determine the influence of each process on the yield and composition of the derived gas, oil and char products. The influence of pyrolysis temperature and heating rate for the conventional pyrolysis and the microwave power was investigated. Two major stages of gas release were observed during biomass pyrolysis, the first being CO/CO and the second one CH/H. This two-stage gas release was much more obvious for the conventional pyrolysis. While similar yield of liquid was obtained for both cases of conventional and microwave pyrolysis (∼46 wt.%), higher gas yield was produced for the conventional pyrolysis; it is suggested that microwave pyrolysis is much faster. When the heating rate was increased, the peak release of CO and CO was moved to higher reaction temperature for both conventional (500 °C) and microwave pyrolysis (200 °C). The production of CH and H were very low at a conventional pyrolysis temperature of 310 °C and microwave pyrolysis temperature of 200 °C (600 and 900 W). However, at higher heating rate of microwave pyrolysis, clear release of CH was observed. This work tentatively demonstrates possible connections and difference for biomass pyrolysis using two different heating resources (conventional and microwave heating)

    Larval Development of Aedes aegypti and Aedes albopictus in Peri-Urban Brackish Water and Its Implications for Transmission of Arboviral Diseases

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    Aedes aegypti (Linnaeus) and Aedes albopictus Skuse mosquitoes transmit serious human arboviral diseases including yellow fever, dengue and chikungunya in many tropical and sub-tropical countries. Females of the two species have adapted to undergo preimaginal development in natural or artificial collections of freshwater near human habitations and feed on human blood. While there is an effective vaccine against yellow fever, the control of dengue and chikungunya is mainly dependent on reducing freshwater preimaginal development habitats of the two vectors. We show here that Ae. aegypti and Ae. albopictus lay eggs and their larvae survive to emerge as adults in brackish water (water with <0.5 ppt or parts per thousand, 0.5–30 ppt and >30 ppt salt are termed fresh, brackish and saline respectively). Brackish water with salinity of 2 to 15 ppt in discarded plastic and glass containers, abandoned fishing boats and unused wells in coastal peri-urban environment were found to contain Ae. aegypti and Ae. albopictus larvae. Relatively high incidence of dengue in Jaffna city, Sri Lanka was observed in the vicinity of brackish water habitats containing Ae. aegypti larvae. These observations raise the possibility that brackish water-adapted Ae. aegypti and Ae. albopictus may play a hitherto unrecognized role in transmitting dengue, chikungunya and yellow fever in coastal urban areas. National and international health authorities therefore need to take the findings into consideration and extend their vector control efforts, which are presently focused on urban freshwater habitats, to include brackish water larval development habitats

    Best practices for operating underwater gliders in Atlantic Canada

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    Ocean gliders are versatile tools for making ocean observations. This paper summarizes the experience, of nearly two decades, of glider observing activity in Atlantic Canada. It reviews key considerations for operating gliders based on the experience and the lessons learned. This paper has three main goals: 1. To provide new and emerging glider users with guidance and considerations for developing a glider program. 2. Review the literature on sensor development for gliders and the use of gliders. 3. To highlight different mission scenarios that include enough practical considerations to support operating gliders. The use of gliders is rapidly expanding, but the documentation and consolidation of best practices for their operational use in Atlantic Canada remains underdeveloped. This summary provides a guide that should be helpful both to new and experienced glider operators and potential users, to observe the oceanography of this region and addresses regional challenges. We believe documenting our experience will be also helpful to the global glider community. We summarize the most critical considerations of utilizing gliders. We review the issues specific to the platform use and concerns about how to optimize the use of key sensors to contribute to an oceanographic observing program

    Diagnosing Norms Surrounding Sexual Harassment at a Jordanian University

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    Sexual harassment (SH) is a form of gender-based violence (GBV) that negatively impacts women’s physical, mental, social, and financial well-being. Although SH is a global phenomenon, it also is a contextualized one, with local and institutional norms influencing the ways in which harassment behavior manifests. As more women attend institutions of higher education in Jordan, these women are at increased risk of experiencing SH in university settings, with potential implications for their health and future employment. Social norms theory, which examines the informal rules governing individual behavior within groups, has been a useful framework for understanding and developing interventions against GBV globally. We sought to apply a social-norms lens to the understanding and prevention of SH at a Jordanian university. To gain a comprehensive and nuanced picture of social norms surrounding SH, we collected qualitative data using three complementary methods: focus group discussions (n = 6) with male and female students (n = 33); key informant interviews with staff and faculty (n = 5); and a public, participatory event to elicit anonymous short responses from students (n = 317). Using this data, we created a codebook incorporating social-norms components and emergent themes. As perceived by participants, SH was unacceptable yet common, characterized as a weak norm primarily because negative sanctioning of harassers was unlikely. Distal norms related to gender and tribal affiliation served to weaken further norms against SH by blaming the victim, preventing reporting, discouraging bystander intervention, and/or protecting the perpetrator. The complexity of the normative environment surrounding SH perpetration will necessitate the use of targeted, parallel approaches to change harmful norms. Strengthening weak norms against SH will require increasing the likelihood of sanctions, by revising university policies and procedures to increase accountability, increasing the acceptability of bystander intervention and reporting, and fostering tribal investment in sanctioning members who harass women. Creating dialogue that emphasizes the harmful nature of SH behaviors and safe spaces to practice positive masculinity also may be an effective strategy to change how male students interact in the presence of peers. Any social norms change intervention will need to consider the various reference groups that dictate and enforce norms surrounding SH
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