Diffusion-weighted magnetic resonance imaging of human skeletal muscles: gender-, age- and muscle-related differences in apparent diffusion coefficient

Purpose

To evaluate the apparent diffusion coefficient (ADC) of skeletal muscle based on signal intensity (SI) attenuation vs. increasing b values and to determine ADC differences in skeletal muscles between genders, age groups and muscles.

Materials and Methods

Diffusion-weighted images (b values in the range of 0–750 s/mm² at increments of 50 s/mm²) of the ankle dorsiflexors (116 subjects) and the erector spinae muscles (86 subjects) were acquired with a 1.5-T MR device. From the two different slopes obtained in SI vs. b-value logarithmic plots, ADC^b0–50 (b values=0 and 50 s/mm²) reflected diffusion and perfusion, while ADC^b50–750 (b values in the range of 50–750 s/mm² at increments of 50 s/mm²) approximated the true diffusion coefficient. Moreover, to evaluate whether this b-value combination is appropriate for assessing the flow component within muscles, diffusion-weighted images of the ankle dorsiflexors (10 subjects) were obtained before and during temporal arterial occlusion.

Results

ADC^b0–50 and ADC^b50–750 were found to be 2.64×10^–3 and 1.44×10^–3 mm²/s in the ankle dorsiflexors, and 3.02×10^–3 and 1.49×10^–3 mm²/s in the erector spinae muscles, respectively. ADC^b0–50 was significantly higher than ADC^b50–750 in each muscle (P<.01). The erector spinae muscles showed significantly higher ADC values than the ankle dorsiflexors (P<.01). However, for each muscle, there were few significant gender- and age-related ADC differences. Following temporal occlusion, ADC^b0–50 of the ankle dorsiflexors decreased significantly from 2.49 to 1.6×10^–3 mm²/s (P<.01); however, ADC^b50–750 showed no significant change.

Conclusion

Based on the SI attenuation pattern, muscle ADC could be divided into ADC that reflects both diffusion and perfusion, and ADC that approximates a true diffusion coefficient. There were significant differences in ADC of functionally distinct muscles. However, we barely found any gender- or age-related ADC differences for each muscle.     

Optical computing by a vector holographic memory system

We propose what is to our knowledge a novel holographic memory system that is simultaneously applicable to data storage and optical computing. We introduce a polarization-modulated reference beam into holographic recording. A desired spatial-frequency component of an object beam is recorded as a polarization-modulated grating, and the other component is recorded as an intensity-modulated grating. Since the polarization-modulated grating rotates the polarization axis of the incident light by 90 degrees , it is possible to distinguish the desired spatial-frequency component of the retrieved image. Utilizing this property, we have successfully performed spatial-frequency filtering and frequency-selective matched filtering. The system is capable of a variety of optical computations, depending on the design of the polarization modulation.     

Effect of creep prestrain on subsequent plastic deformation

The effect of creep prestrain on subsequent plastic deformation is experimentally investigated. The experiments are performed by subjecting thin-walled tubular specimens of stainless steel SUS 304 after creep prestraining to combined axial load and torsion at room temperature to 600°C. The stress-strain relations subsequent to creep prestrain are determined under combined stress state with and without temperature changes in prestraining and subsequent plastic straining. On the experimental results, the plastic hardening effects by creep prestrain are discussed under various temperature conditions. The subsequent stress-strain relations are compared with the calculated results on the equi-plastic strain surfaces.     

Optical noise reduction by reconstructing positive and negative images from Fourier holograms in coaxial holographic storage systems

A technique for reconstructing positive and negative images from an identical intensity-modulated hologram is demonstrated theoretically and experimentally by use of a coaxial holographic storage system. Negative images are obtained by adding a phase-modulated dc component of signal beam on reading. By comparing positive and negative images, the bit error rate (BER) is improved by two orders of magnitude. This technique can reduce optical noise of reconstructed images to attain low BERs.     

Artificial G-wire switch with 2,2'-bipyridine units responsive to divalent metal ions

Development of a guanine nanowire (G-wire) that is controllable and can be switched by external signals is important for the creation of molecular electronic technologies. Here, we constructed a G-wire in which the thymines of the main chain of d(G4T4G4) were replaced with 2,2'-bipyridine units, which have two aromatic rings that rotate arbitrarily upon coordination with metal ions. Circular dichroism of the DNA oligonucleotides with or without the 2,2'-bipyridine unit showed that divalent metal ions induce the bipyridine-containing oligonucleotide to switch from an antiparallel to a parallel G-quadruplex. Native polyacrylamide gel electrophoresis showed that the parallel-stranded G-quadruplex DNA had a high-order structure. Circular dichroism and native gel electrophoresis analyses suggested that adding Na2EDTA causes a reverse structural transition from a parallel-stranded high-order structure to an antiparallel G-quadruplex. Moreover, atomic force microscopy showed a long nanowire ( approximately 200 nm) in the presence of Ni2+ but no significant image in the absence of Ni2+ or in the presence of both Ni2+ and Na2EDTA. These observations revealed that the parallel-stranded high-order structure is a G-wire containing numerous DNA oligonucleotide strands bound together via divalent metal ion-2,2'-bipyridine complexes. Finally, we found that alternating addition of Ni2+ and Na2EDTA can cycle the G-wire between the high-order and disorganized structures, with an average cycling efficiency of 0.95 (i.e., 5% loss per cycle). These results demonstrate that a DNA oligonucleotide incorporating the 2,2'-bipyridine unit acts as a G-wire switch that can be controlled by chemical input signals, namely, divalent metal ions.     

Allergy-preventive flavonoids from Xanthorrhoea hastilis

Allergy-preventive activity was demonstrated for an extract of resins from Xanthorrhoea hastilis R. BR. in a search for allergy-preventive substances from natural sources. By bioassay-directed fractionation of this plant extract, a new flavanone, 3',5'-dihydroxy-7,4'-dimethoxyflavanone (1), and two new chalcones, 3,5,2'-trihydroxy-4,4'-dimethoxychalcone (2) and 5,2'-dihydroxy-3,4,4'-trimethoxychalcone (3), were isolated together with five known compounds, 5'-hydroxy-7,3',4'-trimethoxyflavanone (4), 3'-hydroxy-7,4'-dimethoxyflavanone (5), liquiritigenin 7-methyl ether (6), 4,2'-dihydroxy-4'-methoxychalcone (7) and sakuranetin (8). The structures of 1, 2 and 3 were elucidated by spectroscopic methods. All of these compounds showed allergy-preventive effects.     

Some New Protective Groups for Stabilizing Low Coordinated Phosphorus Compounds

Abstract

Sterically stabilized diphosphenes and 1,3-diphosphaallenes by 2, 4 - tri- t - butylphenyl or 2,4,6-tri-t- pentylphenyl groups were prepared.     

Fullerene-C60/liposome complex: Defensive effects against UVA-induced damages in skin structure,nucleus and collagen type I/IV fibrils,and the permeability into human skin tissue

We previously reported biological safety of fullerene-C60 (C60) incorporated in liposome consisting of hydrogenated lecithin and glycine soja sterol, as Liposome-Fullerene (0.5% aqueous phase; a particle size, 76 nm; Lpsm-Flln), and its cytoprotective activity against UVA. In the present study, Lpsm-Flln was administered on the surface of three-dimensional human skin tissue model, rinsed out before each UVA-irradiation at 4 J/cm², and thereafter added again, followed by 19-cycle-repetition for 4 days (sum: 76 J/cm²). UVA-caused corneum scaling and disruption of epidermis layer were detected by scanning electron microscopy. Breakdown of collagen type I/IV, DNA strand cleavage and pycnosis/karyorrhexis were observed in vertical cross-sections of UVA-irradiated skin models visualized with fluorescent immunostain or Hoechst 33342 stain. These skin damages were scarcely repressed by liposome alone, but appreciably repressed by Lpsm-Flln of 250 ppm, containing 0.75 ppm of C60-equivalent to a 1/3300-weight amount vs. the whole liposome. Upon administration with Lpsm-Flln [16.7 μM (12 ppm): C60-equivalent] on human abdomen skin biopsies mounted in Franz diffusion cells, C60 permeated after 24 h into the epidermis at 1.86 nmol/g tissue (1.34 ppm), corresponding to 0.3% of the applied amount and a 9.0-fold dilution rate, but C60 was not detected in the dermis by HPLC, suggesting no necessity for considering a toxicity of C60 due to systemic circulation via dermal veins. Thus Lpsm-Flln has a potential to be safely utilized as a cosmetic anti-oxidative ingredient for UVA-protection.