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Background: Gut microflora contributes to the nutritional metabolism of the host and to strengthen its immune system. However, if the intestinal barrier function of the living body is destroyed by radiation exposure, the intestinal bacteria harm the health of the host and cause sepsis. Therefore, this study aims to trace short-term radiation-induced changes in the mouse gut microflora-dominant bacterial genus, and analyze the degree of intestinal epithelial damage. Materials and Methods: Mice were irradiated with 0, 2, 4, 8 Gy X-rays, and the gut microflora and intestinal epithelial changes were analyzed 72 hours later. Five representative genera of Actinobacteria, Firmicutes, and Bacteroidetes were analyzed in fecal samples, and the intestine was pathologically analyzed by Hematoxylin-Eosin and Alcian blue staining. In addition, DNA fragmentation was evaluated by the TdT-mediated dUTP nick-end labeling (TUNEL) assay. Results and Discussion: The small intestine showed shortened villi and reduced number of goblet cells upon 8 Gy irradiation. The large intestine epithelium showed no significant morphological changes, but the number of goblet cells were reduced in a radiation dose-dependent manner. Moreover, the small intestinal epithelium of 8 Gy-irradiated mice showed significant DNA damaged, whereas the large intestine epithelium was damaged in a dose-dependent manner. Overall, the large intestine epithelium showed less recovery potential upon radiation exposure than the small intestinal epithelium. Analysis of the intestinal flora revealed fluctuations in lactic acid bacteria excretion after irradiation regardless of the morphological changes of intestinal epithelium. Altogether, it became clear that radiation exposure could cause an immediate change of their excretion. Conclusion: This study revealed changes in the intestinal epithelium and intestinal microbiota that may pave the way for the identification of novel biomarkers of radiation-induced gastrointestinal disorders and develop new therapeutic strategies to treat patients with acute radiation syndrome.

In Japan, the Nuclear Emergency Response Guidelines were announced in 2015 after the Fukushima Daiichi nuclear power plant accident, and each local government is currently formulating a plan for the evacuation of its residents and a subsequent radioactive contamination inspection. However, there are no reports about the state of preparation of the local governments. Therefore, in this study, we conducted a questionnaire survey regarding the preparation status of each local government responsible for the evacuation of its residents and contamination inspections in Japan and the education training status of staff and summarized the results. Results indicated that 17 of 21 local governments, which answered our questionnaire, have been conducting large-scale evacuation drills at least once a year since 2015 in Japan, demonstrating a high awareness of nuclear emergency response. Conversely, results revealed that the number of local government officials familiar with the evacuation plan and/or contamination inspection flow was small, and issues about education for local government officials were discovered. Statistical analysis suggested that the frequency of training might be related to the high educational needs for risk communication.

Monitoring of radioactive materials has been reported in rivers and soil in Fukushima post the Fukushima Daiichi Nuclear Power Plant accident in March 2011. However, there are few reports on the influence of this event on bacteria in forest soils and rivers. Therefore, through amplicon sequencing of 16S rDNA we compared the bacterial flora in river sediment soils from Fukushima prefecture and from an area not exposed to radioactive contamination, Aomori prefecture. The bacterial composition in the Aomori prefecture soil and Fukushima soil were found to be very similar at the phylum level. However, Fukushima soil had significantly fewer Bacteroidetes than the Aomori soil (p = 0.014), while the content of Firmicutes and Latescibacteria (WS3) was significantly higher (p = 0.001, 0.013 respectively). However, no increase in the content of radioactive-resistant bacteria was observed. In future studies, it is necessary to standardise the conditions for soil collection to assess its content of radioactive substances.

Some gastrointestinal bacteria, otherwise known as the ‘intestinal flora’, can cause severe gastrointestinal problems, including sepsis, which are strongly linked to lifestyle-related diseases, including cardiovascular diseases. Several investigations have focused on the long-term changes in the intestinal flora associated with radiation exposure; however, the short-term effects remain unknown. In this study, we tracked the short-term changes in the intestinal flora of mice exposed to different doses of X-ray irradiation (2 Gy and 4 Gy), focusing only on the lactic acid bacteria Bifidobacterium and Lactobacillus. A decrease in the Lactobacillus abundance was detected immediately after irradiation in individuals exposed to both 2 Gy and 4 Gy irradiation. However, mice exposed to 4 Gy of irradiation showed a remarkable increase in Bifidobacterium, indicating a potential role of these bacteria in regeneration of the intestinal epithelial tissue. Studies on changes in intestinal bacteria as a result of radiation exposure are limited. Therefore, continuation of this field of research is expected to provide important fundamental insight into the mechanisms by which radiation causes damage to the intestinal tissues, contributing to the development of sepsis.

Estrogen is involved in lipid metabolism. Menopausal women with low estrogen secretion usually gain weight and develop steatosis associated with abnormal lipid metabolism. A previous study showed that blackcurrant (Ribes nigrum L.) extract (BCE) had phytoestrogen activity. In this study, we examined whether BCE improved lipid metabolism abnormalities and reduced liver steatosis in ovariectomized rats, as a menopausal animal model. Twelve-week-old ovariectomized (OVX) rats were fed a regular diet (Ctrl) or a 3% BCE supplemented diet while sham rats were fed a regular diet for three months. Body weight, visceral fat weight, levels of serum triglycerides, total cholesterol, and LDL cholesterol decreased in the BCE-treated OVX and sham rats, but not in OVX Ctrl rats. The results of hematoxylin and eosin staining revealed that BCE decreased the diameters of adipocytes and the nonalcoholic fatty liver disease activity score. Furthermore, quantitative RTPCR indicated a decreased expression of hepatitis-related genes, such as tumor necrosis factor-&alpha, IL-6, and IL-1&beta, in OVX rats after BCE treatment. This is the first study that reported improvement of lipid metabolism abnormalities in OVX rats by BCE administration. These results suggest that the intake of BCE alleviated dyslipidemia and prevented nonalcoholic steatohepatitis during menopause in this animal model.

Balamuthia mandrillaris is a free-living amoeba that lives in soil and water near human settlements. B. mandrillaris was first isolated from a mandrill baboon that died at the San Diego Zoo Wildlife Park in California in 1986, and the first human infection was reported in 1990. Although reported B. mandrillaris infections are often not properly characterized, it appears that B. mandrillaris invades the living body from the soil and water, either via a wound or the nasal cavity. Most confirmed infections have originated in South and North America. B. mandrillaris inhabits warm climates and is recognized as a pathogen in warm areas such as desert climates and tropical climates. B. mandrillaris has been isolated from environmental samples since 2000, most of which originated from warm areas such as step climates, tropical climates, and desert climates. However, B. mandrillaris may survive in diverse environments, although fewer granulomatous amebic encephalitis patients have been reported in colder Japanese and Northern European regions. In the present study, we conducted a survey of 13 soil samples in Aomori Prefecture located at the northernmost tip of Japan Honshu and successfully isolated one strain of B. mandrillaris from soil for the first time in Japan. In addition, B. mandrillaris gene was detected from several soils. This confirms that B. mandrillaris is capable of spreading to a wider climatic region.

Gut microflora (GM) impacts human health in various ways, both beneficial and detrimental. Recently, it has attracted attention for its application in treatment, as protective agents, and as biomarkers in radiation exposure. In this study, we focused on organic acids that have not yet been reported to be related to radiation exposure; we measured the pH and organic acid content in the faeces of 0, 2, 4 and 8 Gy-irradiated mice. A common trend of fluctuation of some organic acids was observed in each group, suggesting a correlation between radiation exposure and organic acid fluctuation. Lactate fluctuation was similar between 0 and 2 Gy-, and 4 and 8 Gy-irradiated mice. Based on this finding, we suggest that lactate may also be an organic acid that is greatly affected by irradiation.

Sprouted buckwheat (germinated buckwheat seeds) has been traditionally used in the Tsugaru region of Japan. It has been consumed in the Aomori Prefecture, Tsugaru area, for over 350 years. As these buckwheat sprouts are technically the shoots of the plant, they offer several beneficial nutrients. Phytochemicals (metabolic products of plants), such as amino acids and polyphenols, are known to increase markedly upon seed germination. In recent years, attention to the worldwide slow-food orientation and low-glycemic index foods (low-GI foods) has increased. Phytochemicals such as rutin and quercetin, which are abundant in vegetables of the area are attracting attention; thus, studies on the effects of these compounds are increasing. The increase in phytochemical and antioxidant power during germination has turned buckwheat sprouts into a possible functional food, which can allegedly be proclaimed a new vegetable of high commercial value. Here, we discuss traditional vegetables and the phytochemicals present in them and elaborate on the results of our recent study.

Objective: This study aims to investigate the effects of surface bacteria of buckwheat sprouts on obesity. We examine whether these bacteria have probiotic properties. Methods: Since P-36 and P-37 strains were present in large amounts on the buckwheat sprouts surface, identification of species was carried out by intestinal bacteria identification kit and 16S rRNA gene analysis. Subsequently, to investigate the biological effects, P-36 and P-37 strains were divided into two groups, heat-treated dead bacteria and untreated viable bacteria, which were then orally administered to obese model mice exhibiting hyperglycemia every other day for a total of 10 times. After administration, BMI and visceral fat mass were measured, and oral glucose tolerance test was conducted to evaluate glucose tolerance; their influence on blood glucose level and insulin resistance (HOMA-IR) was evaluated. Results: The strain P-36 was identified as Pantoea sp., and P-37 as Kosakonia cowanii. In the group of mice administered the living and dead bacteria of P-36 and P-37, the weight gain rate after the administration was low, and the progression of obesity was suppressed. In the oral glucose tolerance test, an improvement of glucose tolerance and a significant suppression of blood glucose level was confirmed at 0 and 15 min in the group treated with viable P-37. In addition, HOMA-IR was improved in mice treated with both viable and dead P-37 bacteria. Conclusion: The mice administered P-36 and P-37 showed a gradual increase in body weight and a decrease in visceral fat percentage. The mechanism leading to improved blood glucose levels observed in mice administered P-37 strain remains unclear at present. The involvement of buckwheat sprouts-derived bacteria in improving hyperglycemia and reducing obesity during a short time will help to discover new probiotics.