The sequence of about 4,500 nucleotides of the internal part of tobacco mosaic virus (TMV)-tomato strain (L) RNA has been newly determined using cloned cDNAs. Together with the previously determined partial sequences at both ends, the entire sequence of the 6,384 nucleotide genome has been completed. The 130K (1,115 amino acids), 180K (1,615 amino acids), 30K (263 amino acids) and coat protein (158 amino acids) cistrons are located at residues 72-3442, 72-4922, 4906-5700, and 5703-6182 on the genome, respectively. Sequence polymorphism was not observed except for heterogeneity in the length of the A cluster near the 3' end. The homology of the nucleotide sequences of TMV-L and TMV-vulgare, a common strain, is about 80% on average. Remarkable differences between them were found in a part of the N-terminal portion of the 130K/180K protein and the C-terminal portion of the 30K protein. A new method for cDNA cloning was developed by which the cDNA of the 5'-terminus of viral RNA can be cloned efficiently.
Magnetization measurements under direct electric currents were performed for toroidal magnetic ordered state of UNi 4 B to test a recent theoretical prediction of current-induced magnetization in a metallic system lacking local inversion symmetry. We found that each of the electric currents parallel to [2110] and [0001] in the hexagonal 4-index notation induces uniform magnetization in the direction of [0110]. The observed behavior of the induced magnetization is essentially consistent with the theoretical prediction; however it also shows an inconsistency suggesting that the antiferromagnetic state of UNi 4 B could not simply be regarded as a uniform toroidal order in the ideal honeycomb layered structure.The behavior of solids without space-inversion symmetry is one of the most attractive topics in the modern condensed matter physics in the last 50 years, since they show interesting phenomena such as a variety of magnetoelectric (ME) effects 1-3) and parity-mixed superconductivity. 4) The intensive studies in the last decade have revealed that an antisymmetric spin-orbit coupling, which becomes active by space-inversion symmetry breaking, plays a relevant role in these phenomena. 5-9) Furthermore, the very recent theoretical and experimental studies have revealed that the various ME effects can be better understood and categorized on the basis of spatially extended odd-parity multipoles, refered to as cluster or itinerant multipoles. [10][11][12] A toroidal moment is the lowest-rank term of toroidal multipole tensors which appear in the multipolar expansion of an electromagnetic vector potential. 13) It can be active in the system without local space-inversion symmetry on the relevant ion sites. In a spin ordered system, the toroidal moment t is defined as the summation of the vector products of position vector r l and spin S l for magnetic sites l: t = gµ B 2 l r l × S l . The summation is taken over appropriate magnetic basis. In a system where toroidal moments order with a ferroic component, both time-reversal and global space-inversion symmetries are broken, and thus macroscopic ME effects can be expected to occur. For example, ME properties seen in high magnetic fields in a traditional multiferroic system Cr 2 O 3 14) and a novel nonreciprocal directional dichroism observed recently in LiCoPO 4 15) are described on the basis of the concept of toroidal order. The toroidal moment has so far been discussed mainly in insulating systems, where r l corresponds to an electric dipole (electric polarization), and the presence of t in a system can easily be recognized.Recently, Hayami et al. have theoretically investigated possible toroidal ordering in a metallic system with broken localinversion symmetry at magnetic-ion sites. 16) They predicted that exotic magnetotransport and ME effects can occur under the toroidal order. Specifically, they performed a mean-field * analysis for a single-band model on a layered honeycomb structure formed by one type of magnetic ion, and show that a ground state with the occurr...
Magnetic skyrmions are topologically stable swirling spin textures with particle-like character, and have been intensively studied as a candidate of high-density information bit. While magnetic skyrmions were originally discovered in noncentrosymmetric systems with Dzyaloshinskii-Moriya interaction, recently a nanometric skyrmion lattice has also been reported for centrosymmetric rare-earth compounds, such as Gd2PdSi3 and GdRu2Si2. For the latter systems, a distinct skyrmion formation mechanism mediated by itinerant electrons has been proposed, and the search of a simpler model system allowing for a better understanding of their intricate magnetic phase diagram is highly demanded. Here, we report the discovery of square and rhombic lattices of nanometric skyrmions in a centrosymmetric binary compound EuAl4, by performing small-angle neutron and resonant elastic X-ray scattering experiments. Unlike previously reported centrosymmetric skyrmion-hosting materials, EuAl4 shows multiple-step reorientation of the fundamental magnetic modulation vector as a function of magnetic field, probably reflecting a delicate balance of associated itinerant-electron-mediated interactions. The present results demonstrate that a variety of distinctive skyrmion orders can be derived even in a simple centrosymmetric binary compound, which highlights rare-earth intermetallic systems as a promising platform to realize/control the competition of multiple topological magnetic phases in a single material.
Background. Transplantation of bone marrow stromal cells (BMSCs) may contribute to functional recovery after stroke. This study was designed to clarify their mechanisms, trophic effects of neurotrophic factors, and neural differentiation. Methods. Mouse neurons exposed to glutamate were cocultured with mouse BMSCs. Either neutralizing antibodies against brain-derived neurotrophic factor (BDNF) or nerve growth factor (NGF) or Trk inhibitor K252a was added to explore the mechanism of their protective effects. Fluorescence in situ hybridization (FISH) was used to assess BDNF or NGF mRNA expression in BMSCs. The mice were subjected to permanent focal ischemia, and 7 days later, either BMSCs or the vehicle was stereotactically transplanted into the ipsilateral striatum. The mouse brains were processed for FISH and immunostaining 2 or 4 weeks after transplantation. Results. BMSCs significantly ameliorated glutamate-induced neuronal death. Treatment with anti-BDNF antibody significantly reduced their protective effects. FISH analysis showed that the majority of BMSCs expressed BDNF and NGF mRNA in vitro. BMSC transplantation significantly improved the survival of neurons in peri-infarct areas. FISH analysis revealed that approximately half of BMSCs expressed BDNF and NGF mRNA 2 weeks after transplantation; however, the percentage of BDNF and NGF mRNA-positive cells decreased thereafter. Instead, the percentage of microtubule-associated protein 2-positive BMSCs gradually increased during 4 weeks after transplantation. Conclusions. These findings strongly suggest that BDNF may be a key factor underlying the trophic effects of BMSCs. BMSCs might exhibit the trophic effect in the early stage of cell therapy and the phenotypic change toward neural cells thereafter.
Background: Vulnerable and inflamed plaques in the carotid artery are at high risk of ischemic stroke, suggesting the importance of diagnostic modalities to detect them in patients with carotid stenosis with high sensitivity and specificity. Although many investigators have reported that magnetic resonance imaging (MRI) is a useful tool to predict the vulnerable components of carotid plaque, its validity is not established. On the other hand, 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) may be an alternative modality to directly identify the inflamed plaque in carotid artery stenosis. Therefore, this study aimed at evaluating the validity of MRI and FDG-PET to predict vulnerable and inflamed carotid plaque. Methods: This prospective study totally included 25 patients who underwent carotid endarterectomy (CEA) for carotid artery stenosis at our institute between January 2009 and January 2012. Prior to CEA, FDG-PET, black-blood T1-weighted imaging (BB-T1WI), and 3-dimensional time-of-flight (TOF) imaging were performed. The specimens were stained with hematoxylin-eosin to assess the different plaque components (lipid, hemorrhage, calcification, and fibrous tissue). In addition, they were stained with primary antibodies against CD68 (activated macrophages) and matrix metalloproteinase (MMP)-9. Results: High FDG uptake was detected in 13 (52.0%) of 25 patients. All of them had lipid-rich plaque. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) to identify the lipid-rich plaques were all 100% for FDG-PET. More importantly, all of the FDG-positive plaques had strong immunoreactivity against both CD68 and MMP-9. There was a significant correlation between the findings on FDG-PET and those on immunohistochemistry against CD68 and MMP-9 (p = 0.006 and 0.004, respectively). On the other hand, 16 (64.0%) of 25 patients had high signal intensity plaque on BB-T1WI. In 7 of these 16 patients, the lesions also showed high signal intensity on TOF imaging. All of them had a large intraplaque hemorrhage. The sensitivity, specificity, PPV, and NPV to identify a large intraplaque hemorrhage were 70, 100, 100, and 83%, respectively, for MRI. Conclusions: These findings suggest that FDG-PET and MRI are complementary to predict high-risk carotid plaque, such as lipid-rich or hemorrhagic plaque. FDG-PET can accurately predict the lipid-rich and inflamed plaque. MRI is valuable to identify unstable plaque with a large intraplaque hemorrhage. The combination of these two modalities may play an important role in predicting carotid plaque at high risk of ischemic stroke.
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