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- Baldock, Paul A., et al.
(författare)
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Novel role of Y1 receptors in the coordinated regulation of bone and energy homeostasis
- 2007
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Ingår i: Journal of Biological Chemistry. - 1083-351X .- 0021-9258. ; 282:26, s. 19092-19102
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Tidskriftsartikel (refereegranskat)abstract
- The importance of neuropeptide Y (NPY) and Y2 receptors in the regulation of bone and energy homeostasis has recently been demonstrated. However, the contributions of the other Y receptors are less clear. Here we show that Y1 receptors are expressed on osteoblastic cells. Moreover, bone and adipose tissue mass are elevated in Y1(-/-) mice with a generalized increase in bone formation on cortical and cancellous surfaces. Importantly, the inhibitory effects of NPY on bone marrow stromal cells in vitro are absent in cells derived from Y1(-/-) mice, indicating a direct action of NPY on bone cells via this Y receptor. Interestingly, in contrast to Y2 receptor or germ line Y1 receptor deletion, conditional deletion of hypothalamic Y1 receptors in adult mice did not alter bone homeostasis, food intake, or adiposity. Furthermore, deletion of both Y1 and Y2 receptors did not produce additive effects in bone or adiposity. Thus Y1 receptor pathways act powerfully to inhibit bone production and adiposity by nonhypothalamic pathways, with potentially direct effects on bone tissue through a single pathway with Y2 receptors.
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| 3. |
- Lee, Y. -H, et al.
(författare)
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Carrier carrying capacity of one-step grown suspended carbon nanotube bridge with carbon nanotube contact electrodes : For practical one-dimensional electronics
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:7
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Tidskriftsartikel (refereegranskat)abstract
- The authors report the carrier transport and electrical breakdown behaviors of micron-long-channel suspended carbon nanotube (CNT) of carbon-based one-dimensional junction with CNTs as drain and source electrodes. The structure consisted of bundle-type CNT electrode-a CNT channel-bundle-type CNT electrode, produced by one-step in situ direct growth via a unique diluted magnetic nanothick film catalyst at low temperature. The unique suspended all-one-dimensional CNT-based junction provides some insights into recent reports that an electrical breakdown of CNTs can be induced not by the contact problem but by the nonhomogeneously Joule heating along nanotube without release of heat into contacts by the observed breakdown at midlength of a 1-2 μm long channel. The high current carrying all-CNT junction with bridging yield of 90% and stable operation at fixed voltage level can contribute into realization of practical integrated nanoelectronics such as interconnecter and transistor via junction formation of one-step final process. © 2006 American Institute of Physics.
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| 6. |
- Hansen, Klavs, 1958, et al.
(författare)
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Absolute cooling rates of freely decaying fullerenes
- 2009
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Ingår i: Physical Review Letters. ; 103:14
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Tidskriftsartikel (refereegranskat)abstract
- The cooling rates of C$_{60}^-$ have been measured in an electrostatic storage ring between several hundred $\mu$s and several tens of ms with one-photon laser excitation. The absolute energy scale is established by the photon energy and the cooling time interval is derived from the non-exponential decay of the ensemble of hot molecules. The energy decreases due to the combined action of depletion and thermal emission of IR photons with a total energy loss rate that varies inversely proportional to time, 0.9 eV$\cdot 1/t$. The radiative component decreases from a few hundred eV/s at sub ms timescales to several tens of eV/s at 20 ms and confirms that the crossover from depletion to predominantly radiative cooling occurs around 5 ms. The method is applicable to any large molecule or cluster which decays spontaneously, irrespective of the specific decay channel.
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| 9. |
- Toft Sörensen, Andreas, et al.
(författare)
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Activity-dependent volume transmission by transgene NPY attenuates glutamate release and LTP in subiculum
- 2008
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Ingår i: Molecular and Cellular Neuroscience. - : Elsevier BV. - 1044-7431. ; 39:2, s. 37-229
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Tidskriftsartikel (refereegranskat)abstract
- Neuropeptide Y (NPY) gene transduction of the brain using viral vectors in epileptogenic regions can effectively suppress seizures in animals, and is being considered as a promising alternative treatment strategy for epilepsy. Therefore, it is fundamental to understand the detailed mechanisms governing the release and action of transgene NPY in neuronal circuitries. Using whole-cell recordings from subicular neurons, we show that in animals transduced by recombinant adeno-associated viral (rAAV) vector carrying the NPY gene, transgene NPY is released during high-frequency activation of CA1-subicular synapses. Released transgene NPY attenuates excitatory synaptic transmission not only in activated, but also in neighboring, non-activated synapses. Such broad action of transgene NPY may prevent recruitment of excitatory synapses in epileptic activity and could play a key role in limiting the spread and generalization of seizures.
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| 10. |
- Toft Sörensen, Andreas, et al.
(författare)
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Hippocampal NPY gene transfer attenuates seizures without affecting epilepsy-induced impairment of LTP.
- 2009
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 215, s. 328-333
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Tidskriftsartikel (refereegranskat)abstract
- Recently, hippocampal neuropeptide Y (NPY) gene therapy has been shown to effectively suppress both acute and chronic seizures in animal model of epilepsy, thus representing a promising novel antiepileptic treatment strategy, particularly for patients with intractable mesial temporal lobe epilepsy (TLE). However, our previous studies show that recombinant adeno-associated viral (rAAV)-NPY treatment in naive rats attenuates long-term potentiation (LTP) and transiently impairs hippocampal learning process, indicating that negative effect on memory function could be a potential side effect of NPY gene therapy. Here we report how rAAV vector-mediated overexpression of NPY in the hippocampus affects rapid kindling, and subsequently explore how synaptic plasticity and transmission is affected by kindling and NPY overexpression by field recordings in CA1 stratum radiatum of brain slices. In animals injected with rAAV-NPY, we show that rapid kindling-induced hippocampal seizures in vivo are effectively suppressed as compared to rAAV-empty injected (control) rats. Six to nine weeks later, basal synaptic transmission and short-term synaptic plasticity are unchanged after rapid kindling, while LTP is significantly attenuated in vitro. Importantly, transgene NPY overexpression has no effect on short-term synaptic plasticity, and does not further compromise LTP in kindled animals. These data suggest that epileptic seizure-induced impairment of memory function in the hippocampus may not be further affected by rAAV-NPY treatment, and may be considered less critical for clinical application in epilepsy patients already experiencing memory disturbances.
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