著者

Kei Nakayama Mari Kondo Tomoko Okuno Nurhanani Razali Hiroshi Hasegawa

出版者

The Pharmaceutical Society of Japan

雑誌

Biological and Pharmaceutical Bulletin (ISSN:09186158)

巻号頁・発行日

pp.b22-00842, (Released:2022-12-27)

参考文献数

29

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Immune suppression in elderly individuals is one of the most important hygienic problems in aged societies. The primary immune organ thymus is histologically and functionally reduced by aging, which is known as thymic involution. The thymus is also involuted by nutritional deficiency, which frequently occurs in elderly individuals. However, there is no information on the thymic changes caused by nutritional deficiency with aging. Therefore, this study was conducted to examine the histological and molecular responses of the thymus to nutritional deficiency in young and aged mice. The thymic size was significantly smaller in 16- or 18-week-old aged mice than in 7-week-old young mice. Dietary restriction for 48 h reduced the thymic size in young mice, but not in aged mice. Immunostaining with anti-keratin 5 antibody revealed that the integrity of the corticomedullary boundary was maintained in the aged thymus, whereas dietary restriction induced its disorganization in both young and aged thymus. The numbers of IgG-positive cells were increased upon dietary restriction in aged, but not in young, thymus. Dietary restriction, but not aging, upregulated the mRNA levels of Th2-related Il5, Il6, and Il10, whereas aging increased that of Th1-related Ifng. The dietary restriction–induced upregulation of prostanoid-synthesizing enzymes was clearly observed in the young thymus but attenuated in the aged thymus. Thus, nutritional deficiency and aging cause an involuted thymus with different properties. Moreover, the thymus in aged mice does not show further reduction in size by nutritional deficiency but still responds differently compared with that in young mice.

著者

Hideaki Tokusumi Naoto Fujioka Nguyen Minh Tue Akitoshi Goto Go Suzuki Kei Nakayama

出版者

The Japanese Society of Environmental Toxicology

雑誌

環境毒性学会誌 (ISSN:13440667)

巻号頁・発行日

vol.24, pp.1-11, 2021-01-15 (Released:2021-01-15)

参考文献数

27

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In order to develop an optimal method for the investigation of relative potencies of dioxin-like compounds using Japanese medaka, the present study conducted five independent early-life stage toxicity tests using 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as the positive control. First, both short- and long-term effects of TCDD were examined to determine sensitive and highly reproducible endpoints. Then, the outcome and threshold of TCDD toxicities under different experimental conditions, e.g., exposure timing and duration, were compared to develop a cost-effective method. Finally, we decided to observe yolk sac/pericardial edema, hatching failure, and mortality of medaka embryos/larvae within a 28-d experimental period, after 6-h exposure to TCDD at 0-d post fertilization. We obtained the LC50 values of TCDD at 28-d post fertilization based on its concentration in water (6.84 ng/L) or in egg (753 pg/g-egg), and the LC50 values were comparable with those reported in the literature. Thus, in our future studies, relative toxic potencies of dioxin-like compounds will be tested using the method established in this study.

著者

Yukie Narasaki Yumiko Obayashi Sayami Ito Shoko Murakami Jun-Young Song Kei Nakayama Shin-Ichi Kitamura

出版者

The Japanese Society of Fish Pathology

雑誌

魚病研究 (ISSN:0388788X)

巻号頁・発行日

vol.53, no.1, pp.1-9, 2018 (Released:2018-04-03)

参考文献数

36

被引用文献数

3

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Miamiensis avidus is the causative agent of scuticociliatosis in various marine fish species. The virulence factors of the parasite have not been identified, so far. In this study, we examined M. avidus extracellular proteinases (ECPs) as potential virulence factors, using culture supernatants as an ECPs source. We investigated the substrate specificity of ECPs using artificial peptides, and the cytotoxicity of the ECPs was examined using CHSE-214 cells. To elucidate the role of ECPs in ciliate growth, M. avidus was cultured on CHSE-214 cells in the presence of proteinase inhibitors. We detected proteinase activities from the supernatant of M. avidus. Viable CHSE-214 cells decreased significantly in number, when incubated in a medium supplemented with the culture supernatant of M. avidus. The growth of ciliates on CHSE-214 cells was delayed in the presence of PMSF (serine proteinase inhibitor) and E-64 (cysteine proteinase inhibitor). These results suggested that the culture supernatant contained ECPs showing cytotoxicity, and the proteinases facilitated nutrient uptake by the ciliates. Thus, ECPs may be responsible for virulence factors of M. avidus.