Stereospecific Living Radical Polymerization of Designed Bulky Monomers

名古屋大学Nagoya University博士(工学)名古屋大学博士学位論文 学位の種類:博士(工学) (課程) 学位授与年月日:平成24年3月26日doctoral thesi

Excessive whole-body exposure to 28 GHz quasi-millimeter wave induces thermoregulation accompanied by a change in skin blood flow proportion in rats

IntroductionLimited information is available on the biological effects of whole-body exposure to quasi-millimeter waves (qMMW). The aim of the present study was to determine the intensity of exposure to increase body temperature and investigate whether thermoregulation, including changes in skin blood flow, is induced in rats under whole-body exposure to qMMW.MethodsThe backs of conscious rats were extensively exposed to 28 GHz qMMW at absorbed power densities of 0, 122, and 237 W/m2 for 40 minutes. Temperature changes in three regions (dorsal and tail skin, and rectum) and blood flow in the dorsal and tail skin were measured simultaneously using fiber-optic probes.ResultsIntensity-dependent temperature increases were observed in the dorsal skin and the rectum. In addition, skin blood flow was altered in the tail but not in the dorsum, accompanied by an increase in rectal temperature and resulting in an increase in tail skin temperature.DiscussionThese findings suggest that whole-body exposure to qMMW drives thermoregulation to transport and dissipate heat generated on the exposed body surface. Despite the large differences in size and physiology between humans and rats, our findings may be helpful for discussing the operational health-effect thresholds in the standardization of international exposure guidelines

Histological and inflammatory effects of 26.5 GHz quasi-millimeter wave exposure on rat skin

IntroductionInformation regarding the biological effects of localized exposure to quasi-millimeter waves (qMMW) is limited. Given that qMMW exposure can elevate skin temperature and potentially induce thermal injury, further investigation is required. In this study, we aimed to evaluate histological changes and the expression of inflammation-related markers in rat skin tissue locally exposed to 26.5 GHz qMMW, as well as investigate the threshold for inflammatory responses.MethodsThe dorsal skin of rats was locally exposed to 26.5 GHz qMMW at absorbed power densities (APD) of 0, 250, 370, and 500 W/m2 for 18 min using a patch antenna. Histological changes and expression patterns of inflammation-related markers were examined in skin tissue sections exposed to qMMW. Furthermore, serum levels of prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were measured at each post-exposure time point.ResultsHistological analysis revealed burn-like tissue damage in the 500 W/m2 exposure group, characterized by subepidermal blister formation, epidermal thickening, and dermal edema, which increased in severity over time. Conversely, the lower exposure groups (250 and 370 W/m2) showed no distinct morphological changes, similar to the sham group. The 500 W/m2 group exhibited significantly elevated expression of inducible nitric oxide synthase (iNOS) and ionized calcium-binding adapter molecule 1 (Iba1), particularly in the dermis, dermal white adipose tissue, and sebaceous glands. Serum levels of PGE2 increased in a dose-dependent manner at 24 and 72 h; TNF-α and IL-6 remained undetectable. The skin temperature increased during qMMW exposure, reaching 39.0 ± 0.6°C, 42.4 ± 0.9°C, and 44.8 ± 1.2°C at APDs of 250, 370, and 500 W/m2, respectively.DiscussionLocalized exposure of rat skin to qMMW induces burn-like tissue degeneration and triggers an inflammatory response. This effect may be thermally induced by qMMW irradiation, with the threshold estimated to range between 370 and 500 W/m2 APD under the present experimental conditions. Few studies have demonstrated MMW-induced inflammatory responses in the skin. To the best of our knowledge, this is the first study to clearly define the threshold using APD as a reference. These findings may contribute useful evidence for future revisions of exposure guidelines