英語関係代名詞whichの機能と習得 : コーパスに基づく記述的研究

<div><p></p><p>An estimated 1% or less of nanoparticles (NPs) deposited in the lungs translocate to systemic circulation and enter other organs; however, this estimation may not be accurate given the low sensitivity of existing <i>in vivo</i> NP detection methods. Moreover, the biological effects of such low levels of translocation are unclear. We employed a nano-scale hyperspectral microscope to spatially observe and spectrally profile NPs in tissues and blood following pulmonary deposition in mice. In addition, we characterized effects occurring in blood, liver and heart at the mRNA and protein level following translocation from the lungs. Adult female C57BL/6 mice were exposed via intratracheal instillation to 18 or 162 µg of industrially relevant titanium dioxide nanoparticles (nano-TiO₂) alongside vehicle controls. Using the nano-scale hyperspectral microscope, translocation to heart and liver was confirmed at both doses, and to blood at the highest dose, in mice analyzed 24 h post-exposure. Global gene expression profiling and ELISA analysis revealed activation of complement cascade and inflammatory processes in heart and specific activation of complement factor 3 in blood, suggesting activation of an early innate immune response essential for particle opsonisation and clearance. The liver showed a subtle response with changes in the expression of genes associated with acute phase response. This study characterizes the subtle systemic effects that occur in liver and heart tissues following pulmonary exposure and low levels of translocation of nano-TiO₂ from lungs.</p></div

TEM (a-c) and SEM (d-f) images of crystalline bodies observed on day 28 in CNT_Large samples.

<p>(a) Low magnification TEM image showing large crystals, some up to 40 μm long. (b) Image showing scattered crystalline bodies and CNTs in clusters. (c) Ordered crystalline bodies in the cytosol. (d) SEM image of the ultramicrotomed block revealing the underlying cells prior to milling. The image also shows a few protruding CNTs (white arrowhead) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0116481#pone.0116481.ref027" target="_blank">27</a>]. (e) FIB-SEM image of crystals in a cell. (f) 3D representation of the FIB-SEM stack where a few of the crystals have been traced (yellow), revealing their plate-like structure. Black arrowheads indicate ECP crystals while white arrowheads indicate the CNTs.</p

Representative images of the samples 1 day (a-b), 3 days (c-d), and 28 days (e-f) post exposure for CNT_Small (a,c,e) and CNT_Large (b,d,f).

<p>(a-b) Shows CNT_Small and CNT_Large, respectively, on day 1, where CNTs were mainly found in the alveolar lumen or in the interface between cells. (c-d) On day 3 CNTs were increasingly found in vesicles inside what appeared to be alveolar macrophages, but some CNTs were observed outside cells. (e) On day 28, CNT_Small was found inside vesicles and in the cytosol of cells in large cell agglomerations, but were also found inside vesicles in singular cells. (f) On day 28, there were fewer vesicles containing CNT_Large and the CNTs were more individually spaced in the cytosol. In addition, immune cells were found in large agglomerations indicating inflammation at this stage. Arrowheads points to CNTs.</p

Model showing CNT interactions with lung tissue over time <i>in vivo</i>.

<p>At day 1, most CNTs were found in the alveolar spacing, while a few CNTs were found freely inside cells apparently having entered the cells using a non-endocytotic pathway. At day 3, CNTs are found in the alveolar spacing and a larger number of CNTs are found within vesicles, indicating an endocytotic-pathway. At day 28, most of the CNTs were either taken up by cells or in close relation to cells. Compared to post exposure day 3, the two larger CNTs had more CNTs outside vesicle bounds, indicating CNT escape from vesicles.</p