235 research outputs found
Mitochondrial dysfunction causes Ca2+ overload and ECM degradation-mediated muscle damage in C. elegans
This is the final version. Available on open access from the Federation of American Society of Experimental Biology via the DOI in this recordMitochondrial dysfunction impairs muscle health and causes subsequent muscle wasting. This study explores the role of mitochondrial dysfunction as an intramuscular signal for the extracellular matrix (ECM)-based proteolysis and, consequentially, muscle cell dystrophy. We found that inhibition of the mitochondrial electron transport chain causes paralysis as well as muscle structural damage in the nematode Caenorhabditis elegans. This was associated with a significant decline in collagen content. Both paralysis and muscle damage could be rescued with collagen IV overexpression, matrix metalloproteinase (MMP), and Furin inhibitors in Antimycin A-treated animal as well as in the C. elegans Duchenne muscular dystrophy model. Additionally, muscle cytosolic calcium increased in the Antimycin A-treated worms, and its down-regulation rescued the muscle damage, suggesting that calcium overload acts as one of the early triggers and activates Furin and MMPs for collagen degradation. In conclusion, we have established ECM degradation as an important pathway of muscle damage.-Sudevan, S., Takiura, M., Kubota, Y., Higashitani, N., Cooke, M., Ellwood, R. A., Etheridge, T., Szewczyk, N. J., Higashitani, A. Mitochondrial dysfunction causes Ca2+ overload and ECM degradation-mediated muscle damage in C. elegans.Ministry of Education, Culture, Sports, Science, and Technology (MEXT)Cross-Ministerial Strategic Innovation Promotion ProgramAdvanced Research and Development Programs for Medical Innovation (AMED-CRESTBiotechnology and Biological Sciences Research Council (BBSRC)UK Space AgencyScience and Technology Facilities Council (STFC)Otsuka Toshimi FoundationTohoku UniversityJapan Student Services Organizatio
Rough Surface Effect on Meissner Diamagnetism in Normal-layer of N-S Proximity-Contact System
Rough surface effect on the Meissner diamagnetic current in the normal layer
of proximity contact N-S bi-layer is investigated in the clean limit. The
diamagnetic current and the screening length are calculated by use of
quasi-classical Green's function. We show that the surface roughness has a
sizable effect, even when a normal layer width is large compared with the
coherence length . The effect is as large as that
of the impurity scattering and also as that of the finite reflection at the N-S
interface.Comment: 12 pages, 3 figures. To be published in J. Phys. Soc. Jpn. Vol.71-
Quasiparticle States near the Surface and the Domain Wall in a p_x\pm i p_y-Wave Superconductor
The electronic states near a surface or a domain wall in the p-wave
superconductor are studied for the order parameter of the form p_x\pm i
p_y-wave, which is a unitary odd-parity state with broken time-reversal
symmetry. This state has been recently suggested as the superconducting state
of Sr_2 Ru O_4. The spatial variation of the order parameter and vector
potential is determined self-consistently within the quasi-classical
approximation. The local density of states at the surface is constant and does
not show any peak-like or gap-like structure within the superconducting energy
gap, in contrast to the case of the d-wave superconductors. The influence of an
external magnetic field is mainly observable in the energy range above the bulk
gap. On the other hand, there is a small energy gap in the local density of
states at the domain wall between domains of the two degenerate p_x+i p_y-wave
and p_x-i p_y-wave states.Comment: 26 pages, 9 figures, to be published in J. Phys. Soc. Jpn. Vol. 68
(1999) No. 3, erratum: to appear in J. Phys. Soc. Jpn. Vol. 68 (1999) No.
Spontaneous magnetization and Hall effect in superconductors with broken time-reversal symmetry
Broken time reversal symmetry (BTRS) in d wave superconductors is studied and
is shown to yield current carrying surface states. The corresponding
spontaneous magnetization is temperature independent near the critical
temperature Tc for weak BTRS, in accord with recent data. For strong BTRS and
thin films we expect a temperature dependent spontaneous magnetization with a
paramagnetic anomaly near Tc. The Hall conductance is found to vanish at zero
wavevector q and finite frequency w, however at finite q,w it has an unusual
structure.Comment: 7 pages, 1 eps figure, Europhysics Letters (in press
Strong Anisotropy in Spin Suceptibility of Superfluid 3He-B Film Caused by Surface Bound States
Spin susceptibility of superfluid 3He-B film with specular surfaces is
calculated. It is shown that, when the magnetic field is applied in a direction
perpendiculr to the film, the suseptibility is significantly enhanced by the
contribution from the surface bound states. No such enhancement is found for
the magnetic field parallel to the film. A simplified model with spatially
constant order parameter is used to elucidate the magnetic properties of the
surface bound states. The Majorana nature of the zero energy bound state is
also mentioned.Comment: 4 pages, 4 figure
Numerical Study of Impurity Effects on Quasiparticles within S-wave and Chiral P-wave Vortices
The impurity problems within vortex cores of two-dimensional s-wave and
chiral p-wave superconductors are studied numerically in the framework of the
quasiclassical theory of superconductivity and self-consistent Born
approximation under a trial form of the pair potential. The dispersion and
impurity scattering rate (the inverse of the relaxation time) of the Andreev
bound state localized in vortex cores are deduced from the angular-resoloved
local density of states. The energy dependence of the impurity scattering rates
depends on the pairing symmetry; particularly, in the chiral p-wave vortex core
where chirality and vorticity have opposite sign and hence the total angular
momentum is zero, the impurities are ineffective and the scattering rate is
vanishingly small. Owing to the cancellation of angular momentum between
chirality and vorticity, the chiral p-wave vortex core is similar to locally
realized s-wave region and therefore non-magnetic impurity is harmless as a
consequence of Anderson's theorem. The results of the present study confirm the
previous results of analytical study (J. Phys. Soc. Jpn. {\bf 69} (2000) 3378)
in the Born limit.Comment: 8pages, 9figures, submitted to J. Phys. Soc. Jp
Mass coupling and ^3$He in a torsion pendulum
We present results of the and period shift, , for He
confined in a 98% nominal open aerogel on a torsion pendulum. The aerogel is
compressed uniaxially by 10% along a direction aligned to the torsion pendulum
axis and was grown within a 400 m tall pancake (after compression) similar
to an Andronikashvili geometry. The result is a high pendulum able to
resolve and mass coupling of the impurity-limited He over the
whole temperature range. After measuring the empty cell background, we filled
the cell above the critical point and observe a temperature dependent period
shift, , between 100 mK and 3 mK that is 2.9 of the period shift
(after filling) at 100 mK. The due to the He decreases by an order
of magnitude between 100 mK and 3 mK at a pressure of bar. We
compare the observable quantities to the corresponding calculated and
period shift for bulk He.Comment: 8 pages, 3 figure
Magnetic Field Effect in Josephson tunneling between d-Wave Superconductors
The magnetic field effect in the Josephson tunneling between two d-wave
superconductors are investigated. When the crystal orientation of one (or each)
superconductor relative to the interface normal is such that midgap states
exist at the interface, there is a component of the tunneling current due to
the midgap states. For a junction with a flat {001}|{110} or {100}|{110}
interface, this component is the predominant contribution to the current. The
predicted current-field dependence differs entirely from the conventional
Fraunhofer pattern, in agreement with a published measurement. This is because,
apart from the Fraunhofer factor, the critical current depends on the magnetic
field B through the current density also which is a linear function of B for
weak B.Comment: 5 pages, 2 figure
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