Masayuki Tsuda

Expression of Intercellular Adhesion Molecule-1 and Lymphocyte Function-Associated Antigen-1 on Alveolar Macrophages in the Acute Stage of Radiation-Induced Lung Injury in Rats

We investigated the expression of intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1) on alveolar macrophages and on lung tissue in the early stage of radiation-induced lung injury. Cells in the bronchoalveolar lavage and lung tissue were obtained from rats at various times between 1 and 8 weeks after 20 Gy of 60Co gamma irradiation of a hemithorax. These specimens were stained immunohistochemically with anti-ICAM-1 and anti-LFA-1alpha monoclonal antibodies. The expression of these factors was compared with that of a control group. The total number of alveolar macrophages in the bronchoalveolar lavage was significantly reduced from 1 to 3 weeks, and the number of neutrophils was significantly increased 2 and 3 weeks after irradiation. ICAM-1 and LFA-1 expression on alveolar macrophages was significantly increased starting 1 week after irradiation. The expression of ICAM-1 and LFA-1 on lung tissue was not elevated up to 8 weeks after irradiation. In conclusion, the increased expression of ICAM-1 and LFA-1 on alveolar macrophages as early as 1 week after irradiation suggests that adhesion molecules play a role in the development of radiation-induced lung injury.

Early damage to lung tissue after irradiation detected by the magnetic resonance T2 relaxation time.

We sought to determine whether nuclear magnetic resonance relaxation times of water in tissue would be useful to detect molecular damage in lung tissue within 2 weeks after irradiation. Tissue samples were obtained from the lungs of rats at various times between 1 and 14 days after exposure of a hemithorax to 20 Gy 60Co gamma irradiation. The spin-lattice relaxation time, T1, was measured by the inversion recovery method, and the spin-spin relaxation time, T2, was measured by both the Hahn spin-echo (Hahn T2) and the Carr-Purcell-Meiboom-Gill (CPMG T2) methods. The T2 of lung tissue could be divided into two components, T2 fast (T2f) and T2 slow (T2s), which reflected changes in the intracellular and extracellular water, respectively. The CPMG T2f increased significantly 3 days after irradiation (66.3 +/- 2.3 ms compared to 60.8 +/- 2.6 ms), and the CPMG T2s increased significantly 1 day after irradiation (155 +/- 11 ms compared to 138 +/- 7 ms), prior to the observation of abnormalities upon examination of the lung by light microscopy. The CPMG T2 values increased further up to 14 days after irradiation when significant increases were observed in values for T1, Hahn T2 and water content. Our results indicate that the molecular derangement in irradiated lung tissue was detected by the CPMG T2 measurement in the very early stage, and that MRI may be superior to conventional radiographs for detecting the early damage to lung tissue after irradiation.

Development of an irradiation method of intraoperative radiation therapy for curatively resected rectal cancer

AbstractBackground. Intraoperative radiation therapy (IORT) has been performed to prevent local recurrence of rectal cancer only when positive margins are suspected. To further reduce local recurrence, we attempted to develop a new IORT irradiation method in which electron beam irradiation is administered as uniformly as possible to the intrapelvic dissection surfaces.nMethods. Low anterior resection and abdominoperineal resection were performed in one male and one female cadaver. Electron beam irradiation was administered by four different methods, and absorbed doses were measured at 15 sites within the pelvis. We also attempted to measure absorbed doses at nine sites within the pelvis in 14 patients treated with IORT.nResults. The cadaver study revealed low absorbed doses in the lateral walls of the pelvis when a single irradiation was delivered from the anterior. When the lateral walls of the pelvis were irradiated twice, once each time on the right and left, the absorbed doses were low in the central pelvis and presacrum. Relatively high absorbed doses were achieved in all of these areas by a technique that combined these two methods. Adequate absorbed doses were not achieved by a single irradiation administered from the perineum.nConclusion. This study suggests that electron beam irradiation administered three times to the dissected surfaces in the pelvis after resection of rectal cancer (i.e., to the central pelvis and presacrum from the anterior, and to the left and right lateral walls of the pelvis) is the most suitable method for achieving adequate absorbed doses.

Tissue characterization of pneumonia and irradiated rat lungs with magnetic resonance relaxation times

To interpret the MRI signal intensities, the T1 and T2 values were determined in vitro for rat lungs with radiation pneumonitis, fibrosis or pneumonia, and also for muscle and fat tissues. The transverse magnetization decays mentioned above exhibited two components, a T2 fast (T2f) and a T2 slow (T2s) component. Lungs from rats with pneumonia had significantly longer T2f and T2s values than lungs from rats with radiation pneumonitis and fibrosis. The T2f and T2s values for a pneumonia lung were not significantly different from those of muscle. The measured values of T2f and T2s suggested that radiation pneumonitis and fibrosis likely exhibit lower signal intensities than do muscle and that a pneumonia lung likely exhibits a similar signal intensity to that of muscle on T2-weighted MR images.

The short-term fading of TLDs

Abstract LiF, CaSO4: Dy in LiF and CaF2: Tm were used as thermoluminescent phosphors and their glow curves upon irradiation at room temperature with 60Co gamma-rays were examined at 15 s post-irradiation. The lowest temperature peak (Peak 0) for LiF was at 80°C. For CaSO4: Dy in LiF, a total of six glow peaks were identified in the range between room temperature and 260°C. For CaF2: Tm, seven peaks were observed in the same temperature range.