[en] The purpose of this study is to clarify whether reports of nuclear accidents, particularly the damage done by the 2007 Niigata-ken Chuetsu-Oki earthquake to the Kashiwazaki-Kariwa nuclear power plant in Niigata, Japan, tend to be exaggerated by national media. News related to the Kashiwazaki incident was compared with that for nine other high-profile accidents in Japan, including the 1999 JCO critical accident and the 2005 JR-West Fukuchiyama Line derailment. Articles were extracted from four national newspapers in Japan, focusing on the 30 issues immediately following each accident. The numbers of articles and top stories related to the relevant accidents appearing on the front pages of the newspapers were counted. Based on these numbers, the Kashiwazaki incident was reported at a level similar to the JCO accident and Fukuchiyama line derailment in some newspapers, although these two accidents were more serious than the Kashiwazaki incident. This suggests that at least some newspapers in Japan sensationalized reports of the Kashiwazaki incident. (author)

[en] Radiographic assessment has become essential in examining the function of the soft palate and pharyngeal walls in patients with velopharyngeal insufficiency. However, in our search of the literature, there was no report on the exposure dose during videofluorographic examination of velopharyngeal function in Japan. Radiation dosages from videofluorography were measured by attaching a glass dosimeter to the submental skin in 17 patients undergoing examination of velopharyngeal function. Sixteen patients underwent a complete videofluorographic examination. For these 16 patients, the mean time of examination was 96.4 sec; the mean radiation dosage absorbed by the skin was 14.4 mGy, equivalent to approximately 7 standard skull x-rays and lower than that during other fluoroscopic procedures. This dose was also lower than the threshold dose at which the skin damage occurs. In light of increasing concern among the general public over radiation exposure, we consider that these data should provide useful information to patients being asked to give informed consent for this examination. (author)

[en] Phosphodiesterase (PDE) 7 is a potential therapeutic target for neurological and inflammatory diseases, although in vivo visualization of PDE7 has not been successful. In this study, we aimed to develop [${}^{11}$C]MTP38 as a novel positron emission tomography (PET) ligand for PDE7. [${}^{11}$C]MTP38 was radiosynthesized by ${}^{11}$C-cyanation of a bromo precursor with [${}^{11}$C]HCN. PET scans of rat and rhesus monkey brains and in vitro autoradiography of brain sections derived from these species were conducted with [${}^{11}$C]MTP38. In monkeys, dynamic PET data were analyzed with an arterial input function to calculate the total distribution volume (V${}_T$). The non-displaceable binding potential (BP${}_{ND}$) in the striatum was also determined by a reference tissue model with cerebellar reference. Finally, striatal occupancy of PDE7 by an inhibitor was calculated in monkeys according to changes in BP${}_{ND}$. [${}^{11}$C]MTP38 was synthesized with radiochemical purity ≥99.4% and molar activity of 38.6 ± 12.6 GBq/µmol. Autoradiography revealed high radioactivity in the striatum and its reduction by non-radiolabeled ligands, in contrast with unaltered autoradiographic signals in other regions. In vivo PET after radioligand injection to rats and monkeys demonstrated that radioactivity was rapidly distributed to the brain and intensely accumulated in the striatum relative to the cerebellum. Correspondingly, estimated V${}_T$ values in the monkey striatum and cerebellum were 3.59 and 2.69 mL/cm${}^3$, respectively. The cerebellar V${}_T$ value was unchanged by pretreatment with unlabeled MTP38. Striatal BP${}_{ND}$ was reduced in a dose-dependent manner after pretreatment with MTP-X, a PDE7 inhibitor. Relationships between PDE7 occupancy by MTP-X and plasma MTP-X concentration could be described by Hill's sigmoidal function. We have provided the first successful preclinical demonstration of in vivo PDE7 imaging with a specific PET radioligand. [${}^{11}$C]MTP38 is a feasible radioligand for evaluating PDE7 in the brain and is currently being applied to a first-in-human PET study.