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  • 1
    Electronic Resource
    Electronic Resource
    Airborne observations of the physical and chemical characteristics of the Kuwait oil smoke plume (1991)
    [s.l.] : Nature Publishing Group
    Nature 353 (1991), S. 617-621 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Airborne measurements in the densest part of the smoke plume at about 120km from the burning wells in Kuwait in late March 1991 showed typical particulate mass densities of 500–1,000 µgm−3, mixing ratios of 500–1,000 p.p.b.v. of sulphur dioxide and 30–60 ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/353617a0
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Tabulated statistics for some ion dispersion experiments in turbulent air (1984)
    Springer
    Boundary layer meteorology 28 (1984), S. 89-105 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In July 1977 dispersion experiments with air ions as tracer were carried out at Porton in southern England. Each trial lasted about 40 min. The source height was 5 m. Continuous ion production took place in eight trials for source-sensor distances between 10 and 100m. Ion production in 1 s pulses took place in another four trials for source-sensor distances between 10 and 50 m. Two sensors were positioned at a height of 5 m and one sensor at 4 m. The experimental set-up and the weather conditions are described. Tabulated results comprise concentration frequency distributions, as well as auto- and cross-correlations, both for 0.01 and 0.1 s resolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00119458
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A large coaxial lidar for elastic and inelastic scattering studies of the stratosphere (1976)
    Springer
    Optical and quantum electronics 8 (1976), S. 409-423 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A very powerful, fixed zenith laser radar system, based upon a liquid dye laser, is described in detail. The laser is a linear flashlamp pumped dye system capable of an average power output of 6W at a prf of 3 s−1 using rhodamine 6G dye and about 3W with the same prf using esculin monohydrate dye. The use of this laser as a transmitting source in the lidar system has permitted the detection of Stokes shifted vibration/rotation Raman back-scattered light from neutral nitrogen in the stratosphere and from these measurements, stratospheric temperature profiles have been derived. The lidar has also been used to study elastic backscattering from the stratosphere at two wavelengths and preliminary results of a new technique for studying stratospheric aerosol are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00624832
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    Paper (German National Licenses)
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  • 4
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    Genotoxic capacity of Cd/Se semiconductor quantum dots with differing surface chemistries (2015)
    Oxford University Press
    Details
    Publication Date: 2015-12-31
    Description: Quantum dots (QD) have unique electronic and optical properties promoting biotechnological advances. However, our understanding of the toxicological structure–activity relationships remains limited. This study aimed to determine the biological impact of varying nanomaterial surface chemistry by assessing the interaction of QD with either a negative (carboxyl), neutral (hexadecylamine; HDA) or positive (amine) polymer coating with human lymphoblastoid TK6 cells. Following QD physico-chemical characterisation, cellular uptake was quantified by optical and electron microscopy. Cytotoxicity was evaluated and genotoxicity was characterised using the micronucleus assay (gross chromosomal damage) and the HPRT forward mutation assay (point mutagenicity). Cellular damage mechanisms were also explored, focusing on oxidative stress and mitochondrial damage. Cell uptake, cytotoxicity and genotoxicity were found to be dependent on QD surface chemistry. Carboxyl-QD demonstrated the smallest agglomerate size and greatest cellular uptake, which correlated with a dose dependent increase in cytotoxicity and genotoxicity. Amine-QD induced minimal cellular damage, while HDA-QD promoted substantial induction of cell death and genotoxicity. However, HDA-QD were not internalised by the cells and the damage they caused was most likely due to free cadmium release caused by QD dissolution. Oxidative stress and induced mitochondrial reactive oxygen species were only partially associated with cytotoxicity and genotoxicity induced by the QD, hence were not the only mechanisms of importance. Colloidal stability, nanoparticle (NP) surface chemistry, cellular uptake levels and the intrinsic characteristics of the NPs are therefore critical parameters impacting genotoxicity induced by QD.
    Print ISSN: 0267-8357
    Electronic ISSN: 1464-3804
    Topics: Biology , Medicine
    Published by Oxford University Press
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  • 5
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    Automation and validation of micronucleus detection in the 3D EpiDerm™ human reconstructed skin assay and correlation with 2D dose responses (2014)
    Oxford University Press
    Details
    Publication Date: 2014-04-12
    Description: Recent restrictions on the testing of cosmetic ingredients in animals have resulted in the need to test the genotoxic potential of chemicals exclusively in vitro prior to licensing. However, as current in vitro tests produce some misleading positive results, sole reliance on such tests could prevent some chemicals with safe or beneficial exposure levels from being marketed. The 3D human reconstructed skin micronucleus (RSMN) assay is a promising new in vitro approach designed to assess genotoxicity of dermally applied compounds. The assay utilises a highly differentiated in vitro model of the human epidermis. For the first time, we have applied automated micronucleus detection to this assay using MetaSystems Metafer Slide Scanning Platform (Metafer), demonstrating concordance with manual scoring. The RSMN assay’s fixation protocol was found to be compatible with the Metafer, providing a considerably shorter alternative to the recommended Metafer protocol. Lowest observed genotoxic effect levels (LOGELs) were observed for mitomycin-C at 4.8 µg/ml and methyl methanesulfonate (MMS) at 1750 µg/ml when applied topically to the skin surface. In-medium dosing with MMS produced a LOGEL of 20 µg/ml, which was very similar to the topical LOGEL when considering the total mass of MMS added. Comparisons between 3D medium and 2D LOGELs resulted in a 7-fold difference in total mass of MMS applied to each system, suggesting a protective function of the 3D microarchitecture. Interestingly, hydrogen peroxide (H 2 O 2 ), a positive clastogen in 2D systems, tested negative in this assay. A non-genotoxic carcinogen, methyl carbamate, produced negative results, as expected. We also demonstrated expression of the DNA repair protein N -methylpurine-DNA glycosylase in EpiDerm™. Our preliminary validation here demonstrates that the RSMN assay may be a valuable follow-up to the current in vitro test battery, and together with its automation, could contribute to minimising unnecessary in vivo tests by reducing in vitro misleading positives.
    Print ISSN: 0267-8357
    Electronic ISSN: 1464-3804
    Topics: Biology , Medicine
    Published by Oxford University Press
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  • 6
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    Recommendations, evaluation and validation of a semi-automated, fluorescent-based scoring protocol for micronucleus testing in human cells (2014)
    Oxford University Press
    Details
    Publication Date: 2014-04-12
    Description: Micronucleus (MN) induction is an established cytogenetic end point for evaluating structural and numerical chromosomal alterations in genotoxicity testing. A semi-automated scoring protocol for the assessment of MN preparations from human cell lines and a 3D skin cell model has been developed and validated. Following exposure to a range of test agents, slides were stained with 4'-6-diamidino-2-phenylindole (DAPI) and scanned by use of the MicroNuc module of metafer 4, after the development of a modified classifier for selecting MN in binucleate cells. A common difficulty observed with automated systems is an artefactual output of high false positives, in the case of the metafer system this is mainly due to the loss of cytoplasmic boundaries during slide preparation. Slide quality is paramount to obtain accurate results. We show here that to avoid elevated artefactual-positive MN outputs, diffuse cell density and low-intensity nuclear staining are critical. Comparisons between visual (Giemsa stained) and automated (DAPI stained) MN frequencies and dose-response curves were highly correlated ( R 2 = 0.70 for hydrogen peroxide, R 2 = 0.98 for menadione, R 2 = 0.99 for mitomycin C, R 2 = 0.89 for potassium bromate and R 2 = 0.68 for quantum dots), indicating the system is adequate to produce biologically relevant and reliable results. Metafer offers many advantages over conventional scoring including increased output and statistical power, and reduced scoring subjectivity, labour and costs. Further, the metafer system is easily adaptable for use with a range of different cells, both suspension and adherent human cell lines. Awareness of the points raised here reduces the automatic positive errors flagged and drastically reduces slide scoring time, making metafer an ideal candidate for genotoxic biomonitoring and population studies and regulatory genotoxic testing.
    Print ISSN: 0267-8357
    Electronic ISSN: 1464-3804
    Topics: Biology , Medicine
    Published by Oxford University Press
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  • 7
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    The clastogenicity of 4NQO is cell-type dependent and linked to cytotoxicity, length of exposure and p53 proficiency (2016)
    Oxford University Press
    Details
    Publication Date: 2016-02-11
    Description: 4-Nitroquinoline 1-oxide (4NQO) is used as a positive control in various genotoxicity assays because of its known mutagenic and carcinogenic properties. The chemical is converted into 4-hydroxyaminoquinoline 1-oxide and gives rise to three main DNA adducts, N -(deoxyguanosin-8-yl)-4AQO, 3-(desoxyguanosin- N 2 -yl)-4AQO and 3-(deoxyadenosin- N 6 -yl)-4AQO. This study was designed to assess the shape of the dose–response curve at low concentrations of 4NQO in three human lymphoblastoid cell lines, MCL-5, AHH-1 and TK6 as well as the mouse lymphoma L5178Y cell line in vitro . Chromosomal damage was investigated using the in vitro micronucleus assay, while further gene mutation and DNA damage studies were carried out using the hypoxanthine–guanine phosphoribosyltransferase forward mutation and comet assays. 4NQO showed little to no significant increases in micronucleus induction in the human lymphoblastoid cell lines, even up to 55±5% toxicity. A dose–response relationship could only be observed in the mouse lymphoma cell line L5178Y after 4NQO treatment, even at concentrations with no reduction in cell viability. Further significant increases in gene mutation and DNA damage induction were observed. Hence, 4NQO is a more effective point mutagen than clastogen, and its suitability as a positive control for genotoxicity testing has to be evaluated for every individual assay.
    Print ISSN: 0267-8357
    Electronic ISSN: 1464-3804
    Topics: Biology , Medicine
    Published by Oxford University Press
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  • 8
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    Critical review of the current and future challenges associated with advanced in vitro systems towards the study of nanoparticle (secondary) genotoxicity (2016)
    Oxford University Press
    Details
    Publication Date: 2016-12-24
    Description: With the need to understand the potential biological impact of the plethora of nanoparticles (NPs) being manufactured for a wide range of potential human applications, due to their inevitable human exposure, research activities in the field of NP toxicology has grown exponentially over the last decade. Whilst such increased research efforts have elucidated an increasingly significant knowledge base pertaining to the potential human health hazard posed by NPs, understanding regarding the possibility for NPs to elicit genotoxicity is limited. In vivo models are unable to adequately discriminate between the specific modes of action associated with the onset of genotoxicity. Additionally, in line with the recent European directives, there is an inherent need to move away from invasive animal testing strategies. Thus, in vitro systems are an important tool for expanding our mechanistic insight into NP genotoxicity. Yet uncertainty remains concerning their validity and specificity for this purpose due to the unique challenges presented when correlating NP behaviour in vitro and in vivo . This review therefore highlights the current state of the art in advanced in vitro systems and their specific advantages and disadvantages from a NP genotoxicity testing perspective. Key indicators will be given related to how these systems might be used or improved to enhance understanding of NP genotoxicity.
    Print ISSN: 0267-8357
    Electronic ISSN: 1464-3804
    Topics: Biology , Medicine
    Published by Oxford University Press
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  • 9
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    Tabulated statistics for some ion dispersion experiments in turbulent air (1984)
    Springer
    Details
    Publication Date: 1984-01-01
    Print ISSN: 0006-8314
    Electronic ISSN: 1573-1472
    Topics: Geosciences , Physics
    Published by Springer
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  • 10
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    Climate Change: The IPCC Scientific Assessment. Report Prepared for IPCC Working Group 1. Intergovernmental Panel on Climate Change (1992)
    Taylor & Francis
    Details
    Publication Date: 1992-08-01
    Print ISSN: 0004-0851
    Topics: Geography , Geosciences
    Published by Taylor & Francis
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