ケイタイガタ ケツリュウ ケイソク ソウチ ノ カイハツ ト ソノ オウヨウ

A system monitoring blood flow velocities in the carotid artery has been developed. A continuousDoppler method is used to make elecronic circuits simple. It can be used handily owing toa small size and telemetry. The system is applied for measuring the carotid blood flow velocitiesof human. One of interesting results is that the blood flow velocity waveforms of persons withphysical exercise are different properly from those of persons without ecercise. The developedsystem may therefore be useful for evaluating the effects of physical exercise

31P-NMR スペクトロスコピー ニヨル ブンシ ジョウホウ ノ カツヨウ

Nuclear magnetic resonance（NMR）phenomenon discovered by Bloch and Purcell in 1945 is now used in a clinical diagnostic tool as MRI through the imaging technique suggested in 1973 by Lauterbur. Here, we explain 31P-NMR spectroscopy and the method of observing an enzyme reaction velocity in vivo. When phosphorus compounds are placed in a magnetic field, the phosphorus nucleus absorbs and discharges the energy of radio wave at a specific frequency in proportion to the magnetic field intensity. The effective magnetic field on nucleus is reduced by the surrounding electrons, and the shielding effect of the electrons on nucleus causes to reduce the resonance frequency of the nucleus. The shielding effect is expressed as a chemical shift. We can identify molecular structures based on the chemical shifts of resonance lines, and this technique is called an NMR spectroscopy. The phosphorus compounds such as ATP, phosphocreatine and inorganic phosphate can be detected simultaneously and quantified, based on 31P-NMR spectroscopy of living muscle. We can also measure the reaction velocity of creatine kinase, by using the phenomena of saturation and magnetization transfer on 31P-NMR spectroscopy. The nucleus can be placed in a condition of magnetic saturation by the repeated irradiation of the radio wave at the resonance frequency. When the γ phosphate group of ATP is selectively saturated on living muscle, the resonance line of phosphocreatine becomes small, indicating the magnetization transfer from saturated phosphorus atom of γ phosphate group of ATP to phosphorus atom of phosphocreatine. The phosphate exchange reaction is catalyzed by creatine kinase. The flux of the reaction from phosphocreatine to ATP can be calculated with the measurement of the recovery rate from saturation （spin-lattice relaxation time, T1）of phosphocreatine. The applications on perfused heart isolated from bullfrog and also on human heart and chest skeletal muscle in situ were reported. The decreases in both phosphocreatine concentration and the flux of creatine kinase reaction were found in the patients of congestive heart failure

セイタイ シリョウヨウ カイリョウガタ NMR プローブ ノ サクセイ ト ヒョウカ

We have constructed NMR signal detectors （probes） to measure the NMR spectra of living organs and tissues kept under physiological conditions. The probes consisted of non-magnetic aluminum alloy cylinder to support the detection coil made of cupper, mounted on a Teflon plate with acrylics plates and rods, however, the recovery time to the static magnetic field after turning off of the pulsed gradient field was more than 10 times longer than that of the micro-MRI probe available commercially. The re-design of our probes, such as acrylics cylinder to support the coil, together with readjustment of the eddy current compensation circuit, provided us the recovery time to the static field less than 1 msec, making it possible to measure the diffusion coefficient of Na+ ion using the pulsed field gradient spin echo method. The diffusion coefficient of Na+ ion in skeletal muscle isolated from bullfrog was 0.6 time larger than that in Ringer’s solution, suggesting a high viscosity in the skeletal muscle

Activity of Rho-family GTPases during cell division as visualized with FRET-based probes

Rho-family GTPases regulate many cellular functions. To visualize the activity of Rho-family GTPases in living cells, we developed fluorescence resonance energy transfer (FRET)–based probes for Rac1 and Cdc42 previously (Itoh, R.E., K. Kurokawa, Y. Ohba, H. Yoshizaki, N. Mochizuki, and M. Matsuda. 2002. Mol. Cell. Biol. 22:6582–6591). Here, we added two types of probes for RhoA. One is to monitor the activity balance between guanine nucleotide exchange factors and GTPase-activating proteins, and another is to monitor the level of GTP-RhoA. Using these FRET probes, we imaged the activities of Rho-family GTPases during the cell division of HeLa cells. The activities of RhoA, Rac1, and Cdc42 were high at the plasma membrane in interphase, and decreased rapidly on entry into M phase. From after anaphase, the RhoA activity increased at the plasma membrane including cleavage furrow. Rac1 activity was suppressed at the spindle midzone and increased at the plasma membrane of polar sides after telophase. Cdc42 activity was suppressed at the plasma membrane and was high at the intracellular membrane compartments during cytokinesis. In conclusion, we could use the FRET-based probes to visualize the complex spatio-temporal regulation of Rho-family GTPases during cell division

Effect of exposure to an extremely low frequency- electromagnetic field on the cellular collagen with respect to signaling pathways in osteoblast-like cells

The effect of exposure to extremely low frequency-electromagnetic field (ELFEMF : 3 mT, 60 Hz) on differentiation of mouse osteoblast-like MC3T3-E1 cells was examined together with addition of insulin-like growth factor I (IGF-I). As a marker of the differentiation, the cellular collagen content was determined by the absorbance of Sirius red-stained cells measured at the wavelength of 510-520 nm with an imaging microspectroscopy. Exposure to ELF-EMF increased significantly the collagen in the cells. Treatment with PD98059, an inhibitor of extracellular signal-regulated kinase 1/2 (ERK1/2) activation, reduced the collagen in all of the cells examined on control, IGF-I addition and ELFEMF exposure, however, PD98059 did not prevent the increase in the collagen caused by ELF-EMF exposure, and IGF-I also increased the collagen in the presence of the inhibitor. When phosphatidylinositol 3-kinase (PI3K) pathway was inhibited by LY294002, the increase in collagen induced by ELF-EMF exposure was accelerated, however, the increase in collagen observed by IGF-I addition was suppressed. Treatment with SB203580, an inhibitor of p38 mitogen-activated protein kinase (p38 MAPK), suppressed the increase in the collagen induced by ELF-EMF exposure, whereas IGF-I addition increased the collagen in the presence of the inhibitor. These results suggested that collagen synthesis stimulated by ELF-EMF exposure was carried out by the participation of p38 MAPK pathway, and that PI3K pathway may have the role to suppress the collagen synthesis induced by ELF-EMF exposure, and that the suppression of the PI3K pathway may allow the acceleration of the collagen synthesis

Effects of a 1.5 T time-varying magnetic field on cell volume regulation of bovine adrenal chromaffin cells in hyposmotic media

Effects of a time-varying magnetic field on cell volume regulation by hyposmotic stress in cultured bovine adrenal chromaffin cells were examined. Through regulatory volume decrease (RVD), cell volume of chromaffin cells that were incubated in a hypotonic medium initially increased, reached a peak and finally recovered to the initial value. Two hour exposure to a magnetic field and addition of cytochalasin D increased peak value and delayed return to initial value. Intracellular F-actin contents initially decreased but returned to normal levels after 10 sec. Two hour exposure to the magnetic field and addition of cytochalasin D continuously reduced the F-actin content. Results suggest that exposure to the magnetic field stimulated disruption of the actin cytoskeleton and that the disruption delayed the recovery to the volume prior to osmotic stress

Generation of electromagnetic waves from 0.3 to 1.6 terahertz with a high-T-c superconducting Bi2Sr2CaCu2O8+delta intrinsic Josephson junction emitter

To obtain higher power P and frequency f emissions from the intrinsic Josephson junctions in a high-T-c superconducting Bi2Sr2CaCu2O8+delta single crystal, we embedded a rectangular stand-alone mesa of that material in a sandwich structure to allow for efficient heat exhaust. By varying the current-voltage (I-V) bias conditions and the bath temperature T-b, f is tunable from 0.3 to 1.6 THz. The maximum P of a few tens of mu W, an order of magnitude greater than from previous devices, was found at T-b similar to 55K on an inner I-V branch at the TM(1,0) cavity resonance mode frequency. The highest f of 1.6 THz was found at T-b = 10K on an inner I-V branch, but away from cavity resonance frequencies. A possible explanation is presented