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  • Directory of Open Access Journals (DOAJ)  (72)
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  • 1
    In: Journal of Cardiovascular Magnetic Resonance, 2011, Vol.13(Suppl 1), p.P61-P61
    Description: CMR T2-mapping is a promising tool for characterizing myocardial edema. We applied T2-mapping in volunteers to compare two mapping sequences and to assess feasibility, reproducibility and spatial homogeneity.
    Keywords: Poster Presentation
    ISSN: 1097-6647
    E-ISSN: 1532-429X
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  • 2
    Language: English
    In: 2012, Vol.7(11), p.e48956
    Description: The nanoparticle industry is expected to become a trillion dollar business in the near future. Therefore, the unintentional introduction of nanoparticles into the environment is increasingly likely. However, currently applied risk-assessment practices require further adaptation to accommodate the intrinsic nature of engineered nanoparticles. Combining a chronic flow-through exposure system with subsequent acute toxicity tests for the standard test organism Daphnia magna , we found that juvenile offspring of adults that were previously exposed to titanium dioxide nanoparticles exhibit a significantly increased sensitivity to titanium dioxide nanoparticles compared with the offspring of unexposed adults, as displayed by lower 96 h-EC 50 values. This observation is particularly remarkable because adults exhibited no differences among treatments in terms of typically assessed endpoints, such as sensitivity, number of offspring, or energy reserves. Hence, the present study suggests that ecotoxicological research requires further development to include the assessment of the environmental risks of nanoparticles for the next and hence not directly exposed generation, which is currently not included in standard test protocols.
    Keywords: Research Article ; Agriculture ; Biology ; Materials Science ; Biotechnology ; Neuroscience
    E-ISSN: 1932-6203
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  • 3
    In: PLoS ONE, 2013, Vol.8(11)
    Description: Due to their surface characteristics, nanosized titanium dioxide particles (nTiO 2 ) tend to adhere to biological surfaces and we thus hypothesize that they may alter the swimming performance and behavior of motile aquatic organisms. However, no suitable approaches to address these impairments in swimming behavior as a result of nanoparticle exposure are available. Water fleas Daphnia magna exposed to 5 and 20 mg/L nTiO 2 (61 nm; polydispersity index: 0.157 in 17.46 mg/L stock suspension) for 96 h showed a significantly ( p 〈0.05) reduced growth rate compared to a 1-mg/L treatment and the control. Using three-dimensional video observations of swimming trajectories, we observed a treatment-dependent swarming of D. magna in the center of the test vessels during the initial phase of the exposure period. Ensemble mean swimming velocities increased with increasing body length of D. magna , but were significantly reduced in comparison to the control in all treatments after 96 h of exposure. Spectral analysis of swimming velocities revealed that high-frequency variance, which we consider as a measure of swimming activity, was significantly reduced in the 5- and 20-mg/L treatments. The results highlight the potential of detailed swimming analysis of D. magna for the evaluation of sub-lethal mechanical stress mechanisms resulting from biological surface coating and thus for evaluating the effects of nanoparticles in the aquatic environment.
    Keywords: Research Article
    E-ISSN: 1932-6203
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  • 4
    In: Journal of Cardiovascular Magnetic Resonance, 2011, Vol.13(Suppl 1), p.P152-P152
    Description: According to the wavefront-phenomenon myocardial infarction scar should have a larger extent on the subendocardial than the subepicardial surface. This is important for differentiating ischemic from nonischemic lesions in late gadolinium enhancement (LGE) images.
    Keywords: Poster Presentation
    ISSN: 1097-6647
    E-ISSN: 1532-429X
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  • 5
    In: Journal of Cardiovascular Magnetic Resonance, 2012, Vol.14(Suppl 1), p.O69-O69
    Description: In a large series of 216 consecutive patients CMR could noninvasively differentiate various types of bicuspid aortic valve (BAV) morphology. BAV type was related to the frequency of stenosis but not to the frequency of aortic dilatation.
    Keywords: Oral Presentation
    ISSN: 1097-6647
    E-ISSN: 1532-429X
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  • 6
    Language: English
    In: PLoS ONE, 2011, Vol.6(5), p.e20112
    Description: The production and use of nanoparticles (NP) has steadily increased within the last decade; however, knowledge about risks of NP to human health and ecosystems is still scarce. Common knowledge concerning NP effects on freshwater organisms is largely limited to standard short-term (≤48 h) toxicity tests, which lack both NP fate characterization and an understanding of the mechanisms underlying toxicity. Employing slightly longer exposure times (72 to 96 h), we found that suspensions of nanosized (∼100 nm initial mean diameter) titanium dioxide (nTiO 2 ) led to toxicity in Daphnia magna at nominal concentrations of 3.8 (72-h EC 50 ) and 0.73 mg/L (96-h EC 50 ). However, nTiO 2 disappeared quickly from the ISO-medium water phase, resulting in toxicity levels as low as 0.24 mg/L (96-h EC 50 ) based on measured concentrations. Moreover, we showed that nTiO 2 (∼100 nm) is significantly more toxic than non-nanosized TiO 2 (∼200 nm) prepared from the same stock suspension. Most importantly, we hypothesized a mechanistic chain of events for nTiO 2 toxicity in D. magna that involves the coating of the organism surface with nTiO 2 combined with a molting disruption. Neonate D. magna (≤6 h) exposed to 2 mg/L nTiO 2 exhibited a “biological surface coating” that disappeared within 36 h, during which the first molting was successfully managed by 100% of the exposed organisms. Continued exposure up to 96 h led to a renewed formation of the surface coating and significantly reduced the molting rate to 10%, resulting in 90% mortality. Because coating of aquatic organisms by manmade NP might be ubiquitous in nature, this form of physical NP toxicity might result in widespread negative impacts on environmental health.
    Keywords: Research Article ; Biology ; Chemistry ; Earth Sciences ; Materials Science ; Medicine ; Chemistry ; Public Health And Epidemiology ; Marine And Aquatic Sciences ; Ecology ; Critical Care And Emergency Medicine ; Science Policy ; Biochemistry ; Non-clinical Medicine
    E-ISSN: 1932-6203
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  • 7
    In: PLoS ONE, 2015, Vol.10(5)
    Description: During their aquatic life cycle, nanoparticles are subject to environmentally driven surface modifications (e.g. agglomeration or coating) associated with aging. Although the ecotoxicological potential of nanoparticles might be affected by these processes, only limited information about the potential impact of aging is available. In this context, the present study investigated acute (96 h) and chronic (21 d) implications of systematically aged titanium dioxide nanoparticles (nTiO 2 ; ~90 nm) on the standard test species Daphnia magna by following the respective test guidelines. The nTiO 2 were aged for 0, 1, 3 and 6 d in media with varying ionic strengths (Milli-Q water: approx. 0.00 mmol/L and ASTM: 9.25 mmol/L) in the presence or absence of natural organic matter (NOM). Irrespective of the other parameters, aging in Milli-Q did not change the acute toxicity relative to an unaged control. In contrast, 6 d aged nTiO 2 in ASTM without NOM caused a fourfold decreased acute toxicity. Relative to the 0 d aged particles, nTiO 2 aged for 1 and 3 d in ASTM with NOM, which is the most environmentally-relevant setup used here, significantly increased acute toxicity (by approximately 30%), while a toxicity reduction (60%) was observed for 6 d aged nTiO 2 . Comparable patterns were observed during the chronic experiments. A likely explanation for this phenomenon is that the aging of nTiO 2 increases the particle size at the start of the experiment or the time of the water exchange from 〈100 nm to approximately 500 nm, which is the optimal size range to be taken up by filter feeding D . magna . If subjected to further agglomeration, larger nTiO 2 particles, however, cannot be retained by the daphnids’ filter apparatus ultimately reducing their ecotoxicological potential. This non-linear pattern of increasing and decreasing nTiO 2 related toxicity over the aging duration, highlights the knowledge gap regarding the underlying mechanisms and processes. This understanding seems, however, fundamental to predict the risks of nanoparticles in the field.
    Keywords: Research Article
    E-ISSN: 1932-6203
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  • 8
    Language: English
    In: PLoS ONE, 01 January 2017, Vol.12(4), p.e0174634
    Description: Traditional methods to identify aquatic hyphomycetes rely on the morphology of released conidia, which can lead to misidentifications or underestimates of species richness due to convergent morphological evolution and the presence of non-sporulating mycelia. Molecular methods allow fungal identification irrespective of the presence of conidia or their morphology. As a proof-of-concept, we established a quantitative real-time polymerase chain reaction (qPCR) assay to accurately quantify the amount of DNA as a proxy for the biomass of an aquatic hyphomycete species (Alatospora pulchella). Our study showed discrimination even among genetically closely-related species, with a high sensitivity and a reliable quantification down to 9.9 fg DNA (3 PCR forming units; LoD) and 155.0 fg DNA (47 PCR forming units; LoQ), respectively. The assay's specificity was validated for environmental samples that harboured diverse microbial communities and likely contained PCR-inhibiting substances. This makes qPCR a promising tool to gain deeper insights into the ecological roles of aquatic hyphomycetes and other microorganisms.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 9
    In: PLoS ONE, 2013, Vol.8(5)
    Description: The chemokine receptor CXCR4 regulates cell migration during ontogenesis and disease states including cancer and inflammation. Upon stimulation by the endogenous ligand CXCL12, CXCR4 becomes phosphorylated at multiple sites in its C-terminal domain. Mutations in the CXCR4 gene affecting C-terminal phosphorylation sites are a hallmark of WHIM syndrome, a genetic disorder characterized by a gain-of-CXCR4-function. To better understand how multi-site phosphorylation of CXCR4 is organized and how perturbed phosphorylation might affect CXCR4 function, we developed novel phosphosite-specific CXCR4 antibodies and studied the differential regulation and interaction of three C-terminal phosphorylation sites in human embryonic kidney cells (HEK293). CXCL12 promoted a robust phosphorylation at S346/347 which preceded phosphorylation at S324/325 and S338/339. After CXCL12 washout, the phosphosites S338/339 and S324/325 were rapidly dephosphorylated whereas phosphorylation at S346/347 was long-lasting. CXCL12-induced phosphorylation at S346/347 was staurosporine-insensitive and mediated by GRK2/3. WHIM syndrome-associated CXCR4 truncation mutants lacking the S346/347 phosphosite and the recently identified E343K WHIM mutant displayed strongly impaired phosphorylation at S324/325 and S338/339 as well as reduced CXCL12-induced receptor internalization. Relevance of the S346-S348 site was confirmed by a S346-348A mutant showing strongly impaired CXCL12-promoted phosphorylation at S324/325 and S338/339, defective internalization, gain of calcium mobilization, and reduced desensitization. Thus, the triple serine motif S346-S348 contains a major initial CXCR4 phosphorylation site and is required for efficient subsequent multi-site phosphorylation and receptor regulation. Hierarchical organization of CXCR4 phosphorylation explains why small deletions at the extreme CXCR4 C terminus typically associated with WHIM syndrome severely alter CXCR4 function.
    Keywords: Research Article ; Biology
    E-ISSN: 1932-6203
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  • 10
    Language: English
    In: Knowledge and Management of Aquatic Ecosystems, 01 January 2018, Issue 419, p.43
    Description: A stocking program for the endangered European weatherfish (Misgurnus fossilis L.) was conducted in the German federal states of Rhineland-Palatinate and Hesse, southwest Germany. An initial monitoring enabled to identify local broodstock and to assess habitats regarding their ecological suitability for reintroduction. In a second step, broodstock were caught for artificial propagation and cultured fry were released in previously selected river sectors. Furthermore, reintroduction sectors were biannually monitored to assess stocking success. Within the study period (2014–2016), a total number of approximately 83,500 juveniles were stocked in three river sectors for reintroduction and approximately 85,000 juveniles were stocked in four other river sectors to strengthen existing populations. During the post-release monitoring, 45 individuals were recaptured in two sectors. The documented short-term reintroduction success (i.e. survival of released individuals) indicates appropriateness of the selected stocking strategy. Furthermore, the provided course of action might be transferred to further states or countries and thereby contribute to weatherfish conservation at larger scales.
    Keywords: Conservation ; Artificial Propagation ; Endangered Species ; Stocking ; Rhine ; Agriculture
    E-ISSN: 1961-9502
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