Effect of Immobilization on Insoluble Collagen Concentration and Type I and Type III Collagen Isoforms of Rat Soleus Muscle

Immobilization is often associated with decreased muscle elasticity. This condition is known as muscle contracture; however, the mechanism remains unclear. The purpose of this study was to clarify the mechanism governing muscle contracture in rat soleus muscle by identifying changes in ankle joint mobility, insoluble collagen concentration and type I and type III collagen isoforms following 1- and 3-week immobilizations. Following a 1-week immobilization, range of motion (ROM) of dorsiflexion declined to 90% of the control value; additionally, ROM dropped to 67.5% of the control value after a 3-week immobilization. This finding suggested that ankle joint mobility decreases in conjunction with extended periods of immobilization. Insoluble collagen concentration in soleus muscles, which was unchanged after 1 week of immobilization, increased 3 weeks after immobilization. These results may be indicative of collagen fibers with strong intermolecular cross-links contained in the muscle was made increased relatively by 3 weeks of immobilization. Therefore, the change in intermolecular cross-links may be significant in terms of progress of muscle contracture with longer periods of immobilization. On the other hand, the ratio of type III to type I collagen isoforms in muscular tissue increased following a 1-week immobilization; moreover, this ratio remained constant after 3 weeks of immobilization. These data suggested that muscle immobilization may induce type III collagen isoform expression. The increase in the ratio of type III to type I collagen isoforms do not change in parallel with the increase in the limitation in ROM; however, this phenomenon probably is not closely related to the progress of muscle contracture. The change of collagen isoform in immobilized muscle may be involved in the mechanism governing the progression of muscle fibrosis.     

Motion and rotation of small glissile dislocation loops in stress fields

We derive here for the first time the equations that describe the combined motion and rotation of small prismatic dislocation loops in stress fields. When the applied torque is balanced by the self-torque of the loop, we show how the solution can be obtained for the loop orientation, and how this orientation affects the glide force on the loop.     

A novel action of terpendole E on the motor activity of mitotic Kinesin Eg5

To reveal the mechanism of mitosis, the development of M phase-specific inhibitors is an important strategy. We have been screening microbial products to find specific M phase inhibitors that do not directly target tubulins, and rediscovered terpendole E (TerE) as a novel Eg5 inhibitor. TerE did not affect microtubule integrity in interphase, but induced formation of a monoastral spindle in M phase. TerE inhibited both motor and microtubule-stimulated ATPase activities of human Eg5, but did not affect conventional kinesin from either Drosophila or bovine brain. Although terpendoles have been reported as inhibitors of acyl-CoA:cholesterol O-acyltransferase (ACAT), the Eg5 inhibitory activity of TerE was independent of ACAT inhibition. Taken together, we demonstrate that TerE is a novel Eg5 inhibitor isolated from a fungal strain.     

Spectroelectrochemical characterization of Si-bridged diphenylamines: influence of Si-bridging upon electronic structures of diphenylamines.

Spectroelectrochemical properties of monosilane bridged diphenylamine (5,10-dihydro-2,8-diphenyl-5, 10,10-trimethylphenazasiline, Phenaz) and disilane bridged diphenylamine (2,8-diphenyl-10,11-dihydro-10,11-disila-5,10,10,11,11-pentamethyldibenzo[b,f]azepine, DSiAzep) were investigated. The electrochemical oxidation of Phenaz was reversible and its cyclic voltammogram was almost the same shape as that of diphenylamine (DPA). The electrochemical oxidation of DSiAzep was followed by irreversible reactions leading to the cleavage of the Si-Si bond. On electrochemical oxidations of Phenaz and DPA, the formation of a stable radical cation was observed with UV-Vis spectroscopy. In comparison with the absorption characteristics of oxidized radical cations, it was seen that the oxidized radical cation of Phenaz was more delocalized than that of DPA. In the same way, absorption characteristics of oxidized DSiAzep were observed to be different from those observed in Phenaz and DPA.     

Phase transition behavior and proton conduction mechanism in cesium hydrogen sulfate/silica composite

Proton conduction and crystal structure in CsHSO₄/SiO₂ composite composed of polycrystalline CsHSO₄ and mesoporous silica particles were investigated based on conductivity measurement and characterizations using Raman spectroscopy, XRD, and differential thermal analysis. The conductivity of pure CsHSO₄ abruptly changes at around 414 K (superprotonic phase transition), being accompanied with the structural transformation from a monoclinic phase to a tetragonal phase, while the conductivity of CsHSO₄/SiO₂ composite is significantly larger by over three orders of magnitude than that of pure CsHSO₄ below the critical temperature of the superprotonic phase transition (353-414 K). Raman spectroscopy and XRD indicate that this remarkable conductivity-enhancement in the composite is not due to the stabilization of the tetragonal phase (superprotonic phase) below its critical temperature. The line-broadening of the internal modes in the Raman spectra suggests that the rapid reorientational motion of the HSO₄⁻ ion, which leads to superprotonic conduction, is induced in the composite even below the critical temperature. The reorientational motion of the HSO₄⁻ ion below the critical temperature will occur at the interfacial phase which is structurally disordered and forms between CsHSO₄ and SiO₂ in the mesopores and/or on the surfaces of silica particles. Proton transfer will be accelerated via the interfacial conduction-pathway in the composite.     

Nuclear quadrupole resonance of norephedrine

Toward searching for illegal drugs, we investigated the pulsed nuclear quadrupole resonance (NQR) response of ¹⁴N in (1R,2S)-(-)-norephedrine, based on the predictions of quantum chemical calculations. Two pairs of spectral lines (ν₊=3.089, 3.093 MHz and ν₋=2.594, 2.608 MHz) were observed despite its molecule structure having only a single nitrogen atom. This indicates that the molecular crystal has two nonequivalent nitrogen atoms in the unit cell. The temperature dependence of the NQR frequencies and relaxation properties were investigated for the purpose of accurate remote sensing of the drugs. The NQR frequency shift was approximately 0.23 kHz/K around room temperature. The spin-lattice relaxation and spin-phase memory times were 5.2–10.2 ms and 0.6–1.5 ms, respectively.     

Control of a class of underactuated mechanical systems

In this paper a new control methodology for underactuated mechanical systems is proposed. The basic idea of this method is to combine passive velocity field control with decoupling vector field. In order that the underactuated mechanical systems can be stabilized at the desired position after settling on the desired velocity vector field, novel control strategies are proposed. Proposed control strategies are applied to the underactuated planar three-link manipulator and underactuated planar body. Simulations demonstrate the usefulness and effectiveness of the proposed control methodology.