Biomedical subjects
Publications and source records attributed to M Ikeya.
An X-band electron spin resonance (ESR) imaging apparatus with a pin-hole TE102 mode cavity and a rapid scan coil was constructed. Using this apparatus, ESR imaging of melanin in mouse B16 melanoma was observed for the first time. The ESR spectrum of B16 melanoma is similar to that of natural melanin extracted from sepia officinalis in microwave power dependence.
ESR dosimetry of some construction materials at Hiroshima and Nagasaki was carried out to determine the A-bomb radiation dose. Some minerals exposed to low-level natural radiation over a given geological time period can be also used to determine the intense A-bomb radiation dose. Finally, an ESR cavity and a special NdBFe (Neomax) magnet system for in-vivo measurement of radiation dose of a human tooth without extraction is designed and manufactured.
The effect of secondary electron equilibrium on the ESR dosimetry of x- and gamma-ray irradiation has been studied by using acrylic plates to simulate the soft tissue of the human mouth. Dental x-rays create a different ESR signal pattern at the front surface of the tooth vs the back surface. The effect on radiation build-up of the acrylic plate on gamma-irradiation is dominant at the front but is not appreciable at the back side of the tooth.
Peroxy radical formation in raw coffee beans of different qualities and origins from all over the world has been studied with electron spin resonance (ESR) analysis. The gamma-ray equivalent absorbed dose (ED) which creates the same concentration of radicals is obtained by the additive gamma-ray irradiation of the coffee beans. The ED and the cup quality is somewhat inversely related suggesting that the peroxidation of the unsaturated fatty acid is somewhat indicative of the degree of the aromatic decomposition and rancidity.
Explore the source record for details and available documents.
5 cases with the compatible serological criteria of mixed connective tissue disease described earlier are presented. In 1 of them with a moderate degree of proteinuria, the renal biopsy disclosed membranous nephritis. However, despite the absence of overt clinical renal disease in the other 4 cases, biopsies disclosed membranous nephritis in 1 and mild mesangial proliferative glomerulonephritis in the remaining 3 cases. In the follow-up of these 4 cases, 2 subsequently developed abnormal urinalysis. Electron microscopic examinations demonstrated electron-dense deposits in glomeruli, and 4 of these patients also had microtubular structures in the endothelial cytoplasm. Contrarily to the original concept, our findings suggest that mixed connective tissue disease also induces immune complex disease.
The intraglomerular distribution of fibronectin was examined in 152 renal biopsy specimens with the direct immunofluorescence technique. Fibronectin was detected only in the mesangial area in normal glomeruli, while in proliferative glomerulonephritis, it extended from the mesangium to the pericapillary regions proportionately with the proliferative changes. In membranoproliferative glomerulonephritis, fibronectin globally extended in the glomeruli. Also in membranous nephropathy, fibronectin was observed in the capillary walls despite an absence of proliferation. Electron microscopic examinations revealed that the glomeruli with the pericapillary distribution of fibronectin were mostly found in stage II or III, as determined by WHO criteria. The double immunofluorescence technique demonstrated that in membranous nephropathy fibronectin was on the inner side of the glomerular basement membrane, and that in membranoproliferative glomerulonephritis fibronectin extended concomitantly with the expansion of mesangial matrix. These findings suggest that intraglomerular fibronectin is localized only in the mesangial area in normal glomeruli, and that the pericapillary distribution of fibronectin occurs not only by mesangial proliferation but also by additional unknown mechanisms.
Electron spin resonance (ESR) signals from bone increase with exposure to radiation. This permits the dating of ancient bone from its exposure to natural radiation over the centuries. The ESR technique was used for dating human bones from Brazilian shell mounds. The results were compared with 14C dates on charcoal found near the bone. The natural radiation dose rate of the bones was about 0.01 Gy/year (1 rad/year), similar to that found in Japanese shell-mounds. Ages of the bone samples dated ranged from 2000-5000 years BP.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The degradation of blood constituents in unheparinized dry blood was studied with electron spin resonance (ESR) at various temperatures. The intensity of ESR signals of methemoglobins, non-heme irons and organic radicals in dried human blood increases with time. Considering the kinetics of the signal growth, the formation mechanism of the paramagnetic species was discussed. The ESR signal (g = 4.3) of non-heme iron is usable in estimating the time after bleeding or injury using bloodstains.
TM110 mode and TE111 mode ESR microwave cavities for in vivo human tooth dosimetry are developed. ESR signal from a sample is measured by using microwave leak from the pin hole on the cavity wall. The minimum detectable dose of 2 Gy is obtained by the signal accumulation for 100 sweeps.
A microwave scanning ESR microscope has been developed to study the distribution of paramagnetic ions or radicals in various materials, especially in minerals. The microwave scanning microscope consists of a cavity with an aperture over which a sample is moved using mechanical stages and computer-controlled stepping motors. The EPR signal intensities at all positions are composed on a CRT display as an image. A new TE111-mode cylindrical cavity system was designed to obtain better sensitivity and resolution. ESR images of gamma-rayed human teeth were obtained to study the effect of secondary electrons from the adjacent metal on the defect formation in a tooth.
A case of overexposure of an industrial radiographer using 192Ir sources and having a filmbadge dosimeter record of 104 mSv has been examined with ESR dosimetry of postmortem tooth and bone specimens. ESR measurements of the tooth enamel showed an intense signal of CO2- and gave the equivalent dose (ED) of 14 Gy by the additive dose method using gamma-rays from a source of 60Co. The doses for a finger bone and humerus were 14.7 and 7.0 Gy, respectively. It was concluded that he had been exposed to radiation repeatedly over 10 yr and that ESR dosimetry can give a life-long cumulative dose for personnel using radiation.