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  • 1
    In: Review of Scientific Instruments, AIP Publishing, Vol. 85, No. 10 ( 2014-10-01)
    Abstract: As commercial space flights have become feasible and long-term extraterrestrial missions are planned, it is imperative that the impact of space travel and the space environment on human physiology be thoroughly characterized. Scrutinizing the effects of potentially detrimental factors such as ionizing radiation and microgravity at the cellular and tissue level demands adequate visualization technology. Advanced light microscopy (ALM) is the leading tool for non-destructive structural and functional investigation of static as well as dynamic biological systems. In recent years, technological developments and advances in photochemistry and genetic engineering have boosted all aspects of resolution, readout and throughput, rendering ALM ideally suited for biological space research. While various microscopy-based studies have addressed cellular response to space-related environmental stressors, biological endpoints have typically been determined only after the mission, leaving an experimental gap that is prone to bias results. An on-board, real-time microscopical monitoring device can bridge this gap. Breadboards and even fully operational microscope setups have been conceived, but they need to be rendered more compact and versatile. Most importantly, they must allow addressing the impact of gravity, or the lack thereof, on physiologically relevant biological systems in space and in ground-based simulations. In order to delineate the essential functionalities for such a system, we have reviewed the pending questions in space science, the relevant biological model systems, and the state-of-the art in ALM. Based on a rigorous trade-off, in which we recognize the relevance of multi-cellular systems and the cellular microenvironment, we propose a compact, but flexible concept for space-related cell biological research that is based on light sheet microscopy.
    Type of Medium: Online Resource
    ISSN: 0034-6748 , 1089-7623
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2014
    detail.hit.zdb_id: 209865-9
    detail.hit.zdb_id: 1472905-2
    SSG: 11
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  • 2
    Online Resource
    Online Resource
    The Company of Biologists ; 1990
    In:  Journal of Cell Science Vol. 96, No. 1 ( 1990-05-01), p. 171-188
    In: Journal of Cell Science, The Company of Biologists, Vol. 96, No. 1 ( 1990-05-01), p. 171-188
    Abstract: The spreading of trypsinized XTH-2 cells (a line derived from Xenopus laevis tadpole heart endothélia) on glass was investigated. Three phases can be distinguished: (1) blebbing of rounded cells, first attachment to a solid substratum and formation of a broad smooth contact area; (2) organization of a peripheral zone of actin fibrils and reinforcement of the basal cytoplasm by a stress fibre-like pattern; (3) extension of lamellae. The first phase seems to be independent of a supply of metabolic energy, while the others clearly depend on it. This is concluded from the close relationship between cellular projection area and energization of mitochondria as revealed by (a) the fluorescence intensity of cells vitally stained with the mitochondria-specific fluorochrome DASPMI (2–4-(dimethyl-amino)-styryl-l-methylpyridinium-iodine); (b) the degree of spreading in the presence of inhibitors of respiration; (c) effective amelioration of spreading (phases (2) and (3)) under conditions of high ATP content. In phase (2) the extension of the central part of the cells becomes stabilized, the cell body settles on the basal cytoplasmic layer and further expansion of the projection area is achieved by lamella formation (phase (3)); motile and stabile regions of the cells become separated. This sequence of events is interpreted as a self-organizing process based on the development of internal hydraulic pressure, actin polymerization and contraction of the newly developed actomyosin network. During trypsinization, depolymerization of actin does not occur but rather on addition of Ca2+-containing media. Cellular ATP content drops as well on trypsinization, as on addition of Ca2+. Manganese promotes spreading by decreasing F-actin disassembly and maintaining a high level of cytosolic ATP, most probably because it is not accepted by the calcium pumps. Regarding the association of glycolytic enzymes with F-actin and their influence on actin assembly, lactate dehydrogenase has been inhibited with oxamic acid. This treatment improves the correlation between F-actin content and the degree of spreading; however, the total amount of F-actin remains smaller and the cells spread more.
    Type of Medium: Online Resource
    ISSN: 0021-9533 , 1477-9137
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 1990
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
    SSG: 12
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  • 3
    In: Cancers, MDPI AG, Vol. 11, No. 4 ( 2019-04-19), p. 566-
    Abstract: The mechanistic target of rapamycin (mTOR) is elevated in prostate cancer, making this protein attractive for tumor treatment. Unfortunately, resistance towards mTOR inhibitors develops and the tumor becomes reactivated. We determined whether epigenetic modulation by the histone deacetylase (HDAC) inhibitor, valproic acid (VPA), may counteract non-responsiveness to the mTOR inhibitor, temsirolimus, in prostate cancer (PCa) cells. Prostate cancer cells, sensitive (parental) and resistant to temsirolimus, were exposed to VPA, and tumor cell growth behavior compared. Temsirolimus resistance enhanced the number of tumor cells in the G2/M-phase, correlating with elevated cell proliferation and clonal growth. The cell cycling proteins cdk1 and cyclin B, along with Akt-mTOR signaling increased, whereas p19, p21 and p27 decreased, compared to the parental cells. VPA significantly reduced cell growth and up-regulated the acetylated histones H3 and H4. Cdk1 and cyclin B decreased, as did phosphorylated mTOR and the mTOR sub-complex Raptor. The mTOR sub-member Rictor and phosphorylated Akt increased under VPA. Knockdown of cdk1, cyclin B, or Raptor led to significant cell growth reduction. HDAC inhibition through VPA counteracts temsirolimus resistance, probably by down-regulating cdk1, cyclin B and Raptor. Enhanced Rictor and Akt, however, may represent an undesired feedback loop, which should be considered when designing future therapeutic regimens.
    Type of Medium: Online Resource
    ISSN: 2072-6694
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2527080-1
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