Patients with Parkinson's disease (PD) suffer from gait disturbance that, in some patients, can be improved by rhythmic stimulation. This effect is useful for their rehabilitation, but its ...physiological mechanism is not yet well understood. The purpose of this study is to investigate brain activation patterns with functional magnetic resonance imaging (fMRI) in patients with PD while they are imaging gait with and without rhythmic stimulation.
The participants were 27 right-handed patients with PD (mean age: 76.3±6.6, 11 male), whose Yahr stages ranged from 2 to 3. They could walk independently, had no cognitive impairment, and could walk more smoothly with rhythmic stimulation than without it. As a control group, we examined 7 healthy 25 right-handed volunteers (mean age: 72.0±5.3, 13 males). The participants were asked to image gait with rhythmic stimulation (beep on 100 beats per minute) or with white noise during the fMRI imaging.
In patients with PD, with rthmic sound, the activation pattern was limited to supplementary motor area (SMA) and precentral lobule, while with white noise, the activation pattern was more widespread, including precuneus as well as SMA and precentral lobule (P<0.001, (uncorrected)). In healthy controls, the activation was limited to SMA and precentral lobule both with rhythmic stimulation and with white noise.
Both SMA and precentral lobule were activated while other regions including precuneus were less activated with rhythmic stimulation in patients with PD. This result may suggest that rhythmic stimulation can suppress the overactivation of precuneus to improve the attention and to correct the motor programs for the gait function in these patients. In this study, we could suggest the mechanism of the immediate effect of gait improvement with rhythmic stimulation.
Bone-resorbing osteoclasts are regulated by the relative ratio of the differentiation factor, receptor activator NF-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG). Dental ...tissue-localized-resorbing cells called odontoclasts have regulatory factors considered as identical to those of osteoclasts; however, it is still unclear whether the RANKL/OPG ratio is a key factor for odontoclast regulation in dental pulp. Here, we showed that odontoclast regulators, macrophage colony-stimulating factor-1, RANKL, and OPG were detectable in mouse pulp of molars, but OPG was dominantly expressed. High OPG expression was expected to have a negative regulatory effect on odontoclastogenesis; however, odontoclasts were not detected in the dental pulp of OPG-deficient (KO) mice. In contrast, damage induced odontoclast-like cells were seen in wild-type pulp tissues, with their number significantly increased in OPG-KO mice. Relative ratio of RANKL/OPG in the damaged pulp was significantly higher than in undamaged control pulp. Pulp damages enhanced hypoxia inducible factor-1α and -2α, reported to increase RANKL or decrease OPG. These results reveal that the relative ratio of RANKL/OPG is significant to pulpal odontoclastogenesis, and that OPG expression is not required for maintenance of pulp homeostasis, but protects pulp from odontoclastogenesis caused by damages.
We have used the CANGAROO-III imaging atmospheric Cerenkov telescopes to observe the high-frequency-peaked BL Lacertae (HBL) object PKS 2155-304 between 2006 July 28 (MJD 53,944) and August 2, ...triggered by the H.E.S.S. report that the source was in a high state of TeV gamma-ray emission. A signal was detected at the 4.8 capital sigma level in an effective live time of 25.1 hr during the outburst period. The flux of very high energy gamma rays from the CANGAROO-III observations shows variability on the timescale of less than a few hours. The averaged integral flux above 660 GeV is image cm super(-2) s super(- 1), which corresponds to image45% of the flux observed from the Crab Nebula. Follow-up observations between August 17 (MJD 53,964) and 25 indicate that the source activity had decreased.
Because accretion and merger shocks in clusters of galaxies may accelerate particles to high energies, clusters are candidate sites for the origin of ultra-high-energy (UHE) cosmic rays. A prediction ...was presented for gamma-ray emission from a cluster of galaxies at a detectable level with the current generation of imaging atmospheric Cherenkov telescopes. The gamma-ray emission was produced via inverse Compton upscattering of cosmic microwave background photons by electron-positron pairs generated by collisions of UHE cosmic rays in the cluster. We observed two clusters of galaxies, Abell 3667 and Abell 4038, searching for very high energy gamma-ray emission with the CANGAROO-III atmospheric Cherenkov telescope system in 2006. The analysis showed no significant excess around these clusters, yielding upper limits on the gamma-ray emission. From a comparison of the upper limit for the northwest radio relic region of Abell 3667 with a model prediction, we derive a lower limit for the magnetic field of the region of ~0.1 Delta *mG. This shows the potential of gamma-ray observations in studies of the cluster environment. We also discuss the flux upper limit from cluster center regions using a model of gamma-ray emission from neutral pions produced in hadronic collisions of cosmic-ray protons with the intracluster medium. The derived upper limit of the cosmic-ray energy density within this framework is an order of magnitude higher than that of our Galaxy.
Sub-TeV gamma-ray emission from the northwest rim of the supernova remnant RX J0852.0-4622 was detected with the CANGAROO II telescope and recently confirmed by the HESS group. In addition, the HESS ...data revealed a very wide (up to 2 in diameter), shell-like profile of the gamma-ray emission. We carried out CANGAROO III observations in 2005 January and February with three telescopes and show here the results of threefold coincidence data. We confirm the HESS results about the morphology and the energy spectrum and find that the energy spectrum in the NW rim is consistent with that of the whole remnant.
Menasco showed that a non-split, prime, alternating link that is not a 2-braid is hyperbolic in S3. We prove a similar result for links in closed thickened surfaces S×I. We define a link to be fully ...alternating if it has an alternating projection from S×I to S where the interior of every complementary region is an open disk. We show that a prime, fully alternating link in S×I is hyperbolic. Similar to Menasco, we also give an easy way to determine primeness in S×I. A fully alternating link is prime in S×I if and only if it is “obviously prime”. Furthermore, we extend our result to show that a prime link with fully alternating projection to an essential surface embedded in an orientable, hyperbolic 3-manifold has a hyperbolic complement.
We have observed the giant radio galaxy Centaurus A and the globular cluster omega Centauri in the TeV energy region using the CANGAROO III stereoscopic system. The system has been in operation since ...2004 with an array of four Imaging Atmospheric Cerenkov Telescopes (IACT) with similar to 100 m spacings. The observations were carried out in 2004 March and April. In total, approximately 10 hr of data were obtained for each target. No statistically significant gamma-ray signal has been found above 420 GeV over a wide angular region (a 1 degree radius from the pointing center), and we derive flux upper limits using the wholefield of view. Implications for the total energy of cosmic rays and the density of the cold dark matter are considered.
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