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21.
S. Cocucci F. Di Gerolamo A. Verderio A. Cavallaro G. Colli A. Gorni G. Invernizzi L. Luciani 《Cellular and molecular life sciences : CMLS》1979,35(4):482-484
Summary Measurements were made of contamination of plants grown in soil polluted with tetrachlorodibenzo-p-dioxine. Findings show that the pollutant is absorbed and translocated by the plants studied and suggest that the pollutant may be eliminated in the course of time.Acknowledgment. This research was sponsored by the Regional Government of Lombardy, Italy. The authors would like to thank Prof. Marrè for his continuous interest and for the fruitful discussion. 相似文献
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Junt T Moseman EA Iannacone M Massberg S Lang PA Boes M Fink K Henrickson SE Shayakhmetov DM Di Paolo NC van Rooijen N Mempel TR Whelan SP von Andrian UH 《Nature》2007,450(7166):110-114
Lymph nodes prevent the systemic dissemination of pathogens such as viruses that infect peripheral tissues after penetrating the body's surface barriers. They are also the staging ground of adaptive immune responses to pathogen-derived antigens. It is unclear how virus particles are cleared from afferent lymph and presented to cognate B cells to induce antibody responses. Here we identify a population of CD11b+CD169+MHCII+ macrophages on the floor of the subcapsular sinus (SCS) and in the medulla of lymph nodes that capture viral particles within minutes after subcutaneous injection. Macrophages in the SCS translocated surface-bound viral particles across the SCS floor and presented them to migrating B cells in the underlying follicles. Selective depletion of these macrophages compromised local viral retention, exacerbated viraemia of the host, and impaired local B-cell activation. These findings indicate that CD169+ macrophages have a dual physiological function. They act as innate 'flypaper' by preventing the systemic spread of lymph-borne pathogens and as critical gatekeepers at the lymph-tissue interface that facilitate the recognition of particulate antigens by B cells and initiate humoral immune responses. 相似文献
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Rini M Tobey R Dean N Itatani J Tomioka Y Tokura Y Schoenlein RW Cavalleri A 《Nature》2007,449(7158):72-74
Controlling a phase of matter by coherently manipulating specific vibrational modes has long been an attractive (yet elusive) goal for ultrafast science. Solids with strongly correlated electrons, in which even subtle crystallographic distortions can result in colossal changes of the electronic and magnetic properties, could be directed between competing phases by such selective vibrational excitation. In this way, the dynamics of the electronic ground state of the system become accessible, and new insight into the underlying physics might be gained. Here we report the ultrafast switching of the electronic phase of a magnetoresistive manganite via direct excitation of a phonon mode at 71 meV (17 THz). A prompt, five-order-of-magnitude drop in resistivity is observed, associated with a non-equilibrium transition from the stable insulating phase to a metastable metallic phase. In contrast with light-induced and current-driven phase transitions, the vibrationally driven bandgap collapse observed here is not related to hot-carrier injection and is uniquely attributed to a large-amplitude Mn-O distortion. This corresponds to a perturbation of the perovskite-structure tolerance factor, which in turn controls the electronic bandwidth via inter-site orbital overlap. Phase control by coherent manipulation of selected metal-oxygen phonons should find extensive application in other complex solids--notably in copper oxide superconductors, in which the role of Cu-O vibrations on the electronic properties is currently controversial. 相似文献
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P. Nincheri P. Luciani R. Squecco C. Donati C. Bernacchioni L. Borgognoni G. Luciani S. Benvenuti F. Francini P. Bruni 《Cellular and molecular life sciences : CMLS》2009,66(10):1741-1754
Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid which regulates multiple biological parameters in a number of cell
types, including stem cells. Here we report, for the first time, that S1P dose-dependently stimulates differentiation of adipose
tissue-derived mesenchymal stem cells (ASMC) towards smooth muscle cells. Indeed, S1P not only induced the expression of smooth
muscle cell-specific proteins such as α-smooth muscle actin (αSMA) and transgelin, but also profoundly affected ASMC morphology
by enhancing cytoskeletal F-actin assembly, which incorporated αSMA. More importantly, S1P challenge was responsible for the
functional appearance of Ca2+ currents, characteristic of differentiated excitable cells such as smooth muscle cells. By employing various agonists and
antagonists to inhibit S1P receptor subtypes, S1P2 turned out to be critical for the pro-differentiating effect of S1P, while S1P3 appeared to play a secondary role. This study individuates an important role of S1P in AMSC which can be exploited to favour
vascular regeneration.
Received 06 March 2009; accepted 17 March 2009 相似文献
26.
Estimating and Forecasting Large Panels of Volatilities with Approximate Dynamic Factor Models
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We introduce an approximate dynamic factor model for modeling and forecasting large panels of realized volatilities. Since the model is estimated by means of principal components and low‐dimensional maximum likelihood, it does not suffer from the curse of dimensionality. We apply the model to a panel of 90 daily realized volatilities pertaining to S&P 100 from January 2001 to December 2008. Results show that our model is able to capture the stylized facts of panels of volatilities (comovements, clustering, long memory, dynamic volatility, skewness and heavy tails), and that it performs fairly well in forecasting, in particular in periods of turmoil, in which it outperforms standard univariate benchmarks. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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The sperm-releasing activity of a gonadotropin releasing hormone (GnRH) agonist, Buserelin (GnRH) and hypophysis homogenate (PD) preparations was studied in intact and hypophysectomized (PDX) frogs, Rana esculenta. In addition, human chorion gonadotropin (hCG) was tested in PDX animals, and GnRH antagonist (GnRHA) treatments were carried out in intact and PDX animals, in combination with the hormonal injections. GnRH or PD treatments were able to elicit spermiation in intact and PDX animals. While GnRH, injected 24 h later, was again effective in inducing spermiation in intact animals, this was not the case in PDX frogs. GnRHA counteracted GnRH effects in intact frogs. Moreover, in PDX animals GnRHA injections counteracted the sperm-releasing activity induced by hCG or GnRH, but failed to inhibit sperm-releasing activity induced by PD homogenate. 相似文献
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I. Izzo L. Di Matteo S. Minucci L. Iela M. Di Meglio R. K. Rastogi 《Cellular and molecular life sciences : CMLS》1982,38(1):134-135
Summary Extirpation of the pars distalis of the pituitary or castration in any period of the year cause thumb pad regression. Thumb pad development is regulated by an interaction of both temperature and androgenic hormones.Work done under the C.N.R.-finalized project Biologia della Riproduzione. 相似文献