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Featured researches published by Akitaka Doi.


Biochemical and Biophysical Research Communications | 1982

Purification and characterization of calmodulin from rat liver mitochondria.

Osamu Hatase; Masaaki Tokuda; Toshifumi Itano; Hideki Matsui; Akitaka Doi

Abstract Mitochondrial calmodulin of rat liver was purified and classified. It co-migrated with bovine brain calmodulin in non-denaturing polyacrylamide gel electrophoresis, SDS-polyacrylamide gel electrophoresis and isoelectric focusing. The mitochondrial calmodulin activated Ca2+-dependent phosphodiesterase of bovine brain in the presence of Ca2+. About 80% of the mitochondrial calmodulin was proved to be of cytosol origin. It was easily detached by washing with buffer containing EGTA. The other 20% was intramitochondrial calmodulin; half of it was in the matrix space, and half in the membrane.


International Journal of Infrared and Millimeter Waves | 2000

Development of Submillimeter Wave Catheter Transmitting a Gyrotron Output for Irradiation on Living Bodies

Toshiaki Tatsukawa; Akitaka Doi; M. Teranaka; Hitoshi Takashima; Fuminori Goda; T. Idehara; I. Ogawa; S. Mitsudo; T. Kanemaki

The development of a millimeter and submillimeter wave catheter for irradiation on living bodies using a gyrotron as the radiation power source is described. The GYROTRON FU-IV, optimized for such applications was used in the development. It was operated in both CW and pulsed regime at TE03 and TE32 modes with frequencies 302 GHz and 238 GHz respectively. Irradiation tests were made on thermal papers, beefs and liver of living rats.


Brain Research | 1987

Immunohistochemical localization of calcineurin, calmodulin-stimulated phosphatase, in the rat hippocampus using a monoclonal antibody

Hideki Matsui; Akitaka Doi; Toshifumi Itano; Masahisa Shimada; Jerry H. Wang; Osamu Hatase

Immunohistochemical localization of calcineurin, a calmodulin-stimulated phosphatase, was examined in the rat hippocampus by using a monoclonal antibody VD3 which is specific for the A subunit (61 kDa) of calcineurin. The stratum lucidum, where the mossy fiber terminal forms giant synaptic boutons, showed strong immunoreactivity.


Biochemical and Biophysical Research Communications | 1985

A direct evidence of the localization of mitochondrial calmodulin.

Osamu Hatase; Akitaka Doi; Toshifumi Itano; Hideki Matsui; Yoshiaki Ohmura

The presence and localization of mitochondrial calmodulin was directly proved immuno-electron microscopically by the protein A-gold technique. In the ultra-pure mitochondria the complexes of anti-calmodulin antibody and protein A-gold clearly showed the localization of mitochondrial calmodulin on the inner membrane and in the matrix space.


Japanese Journal of Applied Physics | 2002

Submillimeter Wave Irradiation of Living Bodies using a Gyrotron and a Catheter

Toshiaki Tatsukawa; Akitaka Doi; M. Teranaka; Hitoshi Takashima; Fuminori Goda; T. Idehara; I. Ogawa; T. Kanemaki; Seiji Nishizawa

The development of a submillimeter wave catheter for irradiating on living bodies using a gyrotron as the radiation power source is described. The gyrotron FU-IV is optimized for development. The gyrotron is operated in the CW mode at a frequency of 302 GHz under a magnetic field of approximately 11 T. Irradiation tests using various antennas were performed on cow livers, living rats and malignant tumors implanted in living mice. Irradiation results were considered based on the microwave theory and ray optics.


Japanese Journal of Applied Physics | 2003

Characteristics of a Teflon Rod Antenna for Millimeter- and Submillimeter-Wave Irradiation on Living Bodies

Toshiaki Tatsukawa; Akitaka Doi; M. Teranaka; Hitoshi Takashima; Fuminori Goda; T. Idehara; T. Kanemaki; Seiji Nishizawa; T. Namba

The development of a millimeter- and submillimeter-wave catheter for irradiation on living bodies using a Teflon rod dielectric antenna is described. The power sources of electromagnetic wave are an Impatt oscillator (90 GHz, 0.3 W) and a gyrotron (302 GHz, 30 W). Irradiation tests using various Teflon rod dielectric antennas were performed on cow livers, living rats and a cancerous tumor implanted in living mice. Irradiation results were considered by microwave theory and ray optics.


international conference on infrared, millimeter, and terahertz waves | 2008

Millimeter wave irradiation and invasion into living bodies using AR waveguide vent antennas and Gyrotron

M. Teranaka; Akitaka Doi; I. Ogawa; T. Saito; T. Idehara; Toshiaki Tatsukawa

The microwave invasion into living bodies at a millimeter wave irradiation using gyrotron as the radiation power source is described. The irradiation antennas of the system consist of a Teflon rod dielectric antenna, and a Teflon sheet dielectric antenna set at 2.4 - 5.0 mm diameter catheter waveguide vent. Preliminary measurements on the denaturation distribution of irradiated caw livers suggest that they are suitable for common irradiation apparatus for living bodies in similar case as previous report. [1,2] The power absorption of a living body surface is large in these wavelength regions, because the reflections of the wave are well hold down (impedance-matching) by the anti-reflecting layers (ARL) of dielectrics. [3] We measured the power changing of millimeter wave with ARL antennas thickness by some TE modes using gyrotrons. Transmission tests through catheter waveguides confirm the normal operation of the irradiation apparatus for living bodies.


international conference on infrared, millimeter, and terahertz waves | 2007

Millimeter wave irradiation and invasion into living bodies by the anti-reflecting effect

M. Teranaka; Akitaka Doi; Toshiaki Tatsukawa; S. Mitsudo; T. Saito; T. Idehara; T. Kanemaki; T. Namba

The microwave invasion into living bodies at a millimeter wave irradiation is described. The power sources of millimeter wave are Impatt oscillators (94 GHz, 0.15 W and 0.3 W) for the irradiation tests and Gunn oscillators (90 and 100 GHz, 13 mW) for the reflection study. The irradiation antennas of the system consist of a Teflon rod dielectric antenna ,and a Teflon sheet dielectric antenna set at 2.4 - 5.0 mm diameter catheter waveguide vent. Preliminary measurements on the denaturation distribution and the surface temperature of irradiated beefs suggest that they are suitable for common irradiation apparatus for living bodies in similar case as previous reports. Transmission tests through catheter waveguides confirm the normal operation of the irradiation apparatus for living bodies. The power absorption of a living body surface is large in these wavelength regions, because the reflection of the wave are well hold down (impedance-matching) by the anti-reflecting layers (ARL) of dielectrics. Transmission loss is small by a long Teflon rod dielectrics which can be used a flexible waveguide. Otherwise the anti- reflecting effect is strongly influenced by the internal diameter of the waveguide.


joint international conference on infrared millimeter waves and international conference on teraherz electronics | 2006

Transmission characteristics of 0.3 THz wave using FUCW-I Gyrotron

Akitaka Doi; M. Teranaka; Toshiaki Tatsukawa; T. Idehara; S. Mitsudo; T. Kanemaki; T. Namba

The transmission characteristics of 0.3 THz wave through a circular waveguide whose diameter charged from 90 mm to 5 mm by two taper waveguides was investigated. As a power source, FUCW-I gyrotron ( GYCOM, Russia) was used. The gyrotron is operated in CW regime at weak power (20~ 100 W) Gaussian mode with the frequency of 0.3THz. The usual beam current is 130 mA at the accellated voltage 15 KV. The used antenna consists of a Teflon rod dielectric antenna and an insert rod antenna set at 2.4~5.0 mm waveguide. Under the various conditions, the output power from the antenna was measured by water load.


joint international conference on infrared millimeter waves and international conference on teraherz electronics | 2006

Millimeter wave irradiation and invasion into living bodies using AR waveguide vent antennas

M. Teranaka; Akitaka Doi; Toshiaki Tatsukawa; T. Idehara; S. Mitsudo; T. Kanemaki; T. Namba

The microwave invasion into living bodies at a millimeter wave catheter irradiation is described. The power sources of millimeter wave are an Impatt oscillator (94 GHz, 0.3 W) for the irradiation tests, a Gunn oscillator (90 GHz, 13 mW) for the reflection study, and a gyrotron for high power irradiation. Irradiated samples are cow livers and living rats. In the newly designed irradiation antennas, a part of the copper waveguide is replaced with the flexible Teflon rod.

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