Dynamic Magnetic Resonance Imaging of Femoral Head Perfusion in Femoral Neck Fracture

Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
Biochemical and Biophysical Research Communications (Impact Factor: 2.3). 05/2012; 423(4):627-31. DOI: 10.1016/j.bbrc.2012.05.125
Source: PubMed


Tumor suppressor p53 negatively regulates self-renewal of neural stem cells in the adult murine brain. Here, we report that the p53 null mutation in medaka fish (Oryzias latipes) suppressed neurogenesis in the telencephalon, independent of cell death. By using 5-bromo-29-deoxyuridine (BrdU) immunohistochemistry, we identified 18 proliferation zones in the brains of young medaka fish; in situ hybridization showed that p53 was expressed selectively in at least 12 proliferation zones. We also compared the number of BrdU-positive cells present in the whole telencephalon of wild-type (WT) and p53 mutant fish. Immediately after BrdU exposure, the number of BrdU-positive cells did not differ significantly between them. One week after BrdU-exposure, the BrdU-positive cells migrated from the proliferation zone, which was accompanied by an increased number in the WT brain. In contrast, no significant increase was observed in the p53 mutant brain. Terminal deoxynucleotidyl transferase (dUTP) nick end-labeling revealed that there was no significant difference in the number of apoptotic cells in the telencephalon of p53 mutant and WT medaka, suggesting that the decreased number of BrdU-positive cells in the mutant may be due to the suppression of proliferation rather than the enhancement of neural cell death. These results suggest that p53 positively regulates neurogenesis via cell proliferation.

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Available from: Hideaki Takeuchi
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    • "leptorhynchus: (Zupanc and Horschke, 1995; Zupanc et al., 1996; Zupanc, 2001; Hinsch and Zupanc, 2006); Eigenmannia sp: (Zupanc and Zupanc, 1992); and Brachyhypopomus gauderio: (Dunlap et al., 2011)]. The spatial distribution of brain proliferation zones in adult wave type weakly electric gymnotids roughly resembles that of other teleosts [Astatotilapia burtoni (Maruska et al., 2012); Austrolebias (Fernández et al., 2011); Carassius auratus (Raymond and Easter, 1983; Delgado and Schmachtenberg, 2011); Danio rerio (Maeyama and Nakayasu, 2000; Zupanc et al., 2005; Adolf et al., 2006; Grandel et al., 2006; Ampatzis and Dermon, 2007; Kaslin et al., 2009; Ito et al., 2010; März et al., 2010; Zupanc, 2011); Gasterosteus aculeatus (Ekström et al., 2001); Nothobranchius furzeri (Terzibasi et al., 2012); Odontesthes bonariensis (Strobl-Mazzulla et al., 2010); Oreochromis mossambicus (Teles et al., 2012); Oryzias latipes (Nguyen et al., 1999; Candal et al., 2005a; Alunni et al., 2010; Kuroyanagi et al., 2010; Isoe et al., 2012) and Salmo trutta fario (Candal et al., 2005b)], despite the phylogenetic distance to most of those species. However, differences have been observed that were attributed to the functional specialization of weakly electric fish (Zupanc and Horschke, 1995; Grandel et al., 2006; Grandel and Brand, 2013). "
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    ABSTRACT: Proliferation of stem/progenitor cells during development provides for the generation of mature cell types in the CNS. While adult brain proliferation is highly restricted in the mammals, it is widespread in teleosts. The extent of adult neural proliferation in the weakly electric fish, Gymnotus omarorum has not yet been described. To address this, we used double thymidine analog pulse-chase labeling of proliferating cells to identify brain proliferation zones, characterize their cellular composition, and analyze the fate of newborn cells in adult G. omarorum. Short thymidine analog chase periods revealed the ubiquitous distribution of adult brain proliferation, similar to other teleosts, particularly Apteronotus leptorhynchus. Proliferating cells were abundant at the ventricular-subventricular lining of the ventricular-cisternal system, adjacent to the telencephalic subpallium, the diencephalic preoptic region and hypothalamus, and the mesencephalic tectum opticum and torus semicircularis. Extraventricular proliferation zones, located distant from the ventricular-cisternal system surface, were found in all divisions of the rombencephalic cerebellum. We also report a new adult proliferation zone at the caudal-lateral border of the electrosensory lateral line lobe. All proliferation zones showed a heterogeneous cellular composition. The use of short (24h) and long (30day) chase periods revealed abundant fast cycling cells (potentially intermediate amplifiers), sparse slow cycling (potentially stem) cells, cells that appear to have entered a quiescent state, and cells that might correspond to migrating newborn neural cells. Their abundance and migration distance differed among proliferation zones: greater numbers and longer range and/or pace of migrating cells were associated with subpallial and cerebellar proliferation zones.
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    • "Thus, heat-inducible Cre/loxP site-specific recombination is also applicable for investigating adult neurogenesis in medaka fish. In contrast to mammals with limited neurogenesis in the adult brains, teleost fish such as medaka fish and zebrafish constitutively generate newborn neurons in numerous proliferating zones across the whole brain throughout life [21], [26], [39]–[41]. As the distribution of proliferation zones in the adult brain is mostly conserved among teleost fish, adult neurogenesis is believed to be important for the maintenance and development of the fundamental structure of the fish brain throughout life [21], [41]. "
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    ABSTRACT: Genetic mosaic techniques have been used to visualize and/or genetically modify a neuronal subpopulation within complex neural circuits in various animals. Neural populations available for mosaic analysis, however, are limited in the vertebrate brain. To establish methodology to genetically manipulate neural circuits in medaka, we first created two transgenic (Tg) medaka lines, Tg (HSP:Cre) and Tg (HuC:loxP-DsRed-loxP-GFP). We confirmed medaka HuC promoter-derived expression of the reporter gene in juvenile medaka whole brain, and in neuronal precursor cells in the adult brain. We then demonstrated that stochastic recombination can be induced by micro-injection of Cre mRNA into Tg (HuC:loxP-DsRed-loxP-GFP) embryos at the 1-cell stage, which allowed us to visualize some subpopulations of GFP-positive cells in compartmentalized regions of the telencephalon in the adult medaka brain. This finding suggested that the distribution of clonally-related cells derived from single or a few progenitor cells was restricted to a compartmentalized region. Heat treatment of Tg(HSP:Cre x HuC:loxP-DsRed-loxP-GFP) embryos (0-1 day post fertilization [dpf]) in a thermalcycler (39°C) led to Cre/loxP recombination in the whole brain. The recombination efficiency was notably low when using 2-3 dpf embyos compared with 0-1 dpf embryos, indicating the possibility of stage-dependent sensitivity of heat-inducible recombination. Finally, using an infrared laser-evoked gene operator (IR-LEGO) system, heat shock induced in a micro area in the developing brains led to visualization of clonally-related cells in both juvenile and adult medaka fish. We established a noninvasive method to control Cre/loxP site-specific recombination in the developing nervous system in medaka fish. This method will broaden the neural population available for mosaic analyses and allow for lineage tracing of the vertebrate nervous system in both juvenile and adult stages.
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    ABSTRACT: The Japanese medaka fish, Oryzias latipes, has become a powerful vertebrate model organism in developmental biology and genetics. The present study explores the dielectric properties of medaka embryos during pre-hatching development by means of the electrorotation (ROT) technique. Due to their layered structure, medaka eggs exhibited up to three ROT peaks in the kHz-MHz frequency range. During development from blastula to early somite stage, ROT spectra varied only slightly. But as the embryo progressed to the late-somite stage, the ROT peaks underwent significant changes in frequency and amplitude. Using morphological data obtained by light and electron microscopy, we analyzed the ROT spectra with a three-shell dielectric model that accounted for the major embryonic compartments. The analysis yielded a very high value for the ionic conductivity of the egg shell (chorion), which was confirmed by independent osmotic experiments. A relatively low capacitance of the yolk envelope was consistent with its double-membrane structure revealed by transmission electron microscopy. Yolk-free dead eggs exhibited only one co-field ROT peak, shifted markedly to lower frequencies with respect to the corresponding peak of live embryos. The dielectric data may be useful for monitoring the development and changes in fish embryos' viability/conditions in basic research and industrial aquaculture.
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