What factors were important for dietary improvement in emergency shelters after the Great East Japan Earthquake?

The Great East Japan Earthquake of 2011 left many evacuees with insufficient food and emergency shelter. However, there is no evidence concerning the factors affecting dietary circumstances in emergency shelters after disasters. To clarify the factors that influenced the provision of meals, we reanalyzed a data set from a dietary survey conducted in emergency shelters one month after the Great East Japan Earthquake (2011). Among the 69 shelters in "city A," 53 (79.1%) had food shortages. The possibility of cooking in the emergency shelter improved the provision of meals to evacuees. When comparing emergency shelters with and without cooking equipment, the shelters with cooking equipment provided more meals, as well as more dishes containing grains and vegetables. When there was a gas supply, the twice per day provision of "balanced" meals (containing grains, vegetables, and meat/fish) was more frequent than when there was no gas supply. Interestingly, neither the water supply nor the electricity supply affected the provision of balanced meals. Further, emergency shelters with larger numbers of evacuees had a lower possibility of cooking and lower availability of gas supply. Our results demonstrate that early improvements to post-disaster meal provision may maintain the health of evacuees. Such improvements could be achieved by 1) the speedy restoration of the gas supply to enable cooking, and 2) limiting the number of evacuees per emergency shelter.

Ionizing radiation leads to the replacement and de novo production of colonic Lgr5(+) stem cells.

Tissue stem cells have self-renewal capability throughout their whole life, which is high enough to lead to the accumulation of DNA damage in a stem cell pool. Whether radiation-induced damage accumulates in tissue stem cells remains unknown, but could be investigated if the fate of tissue stem cells could be followed after irradiation. To realize this goal, we used an Lgr5-dependent lineage tracing system that allows the conditional in vivo labeling of Lgr5(+) intestinal stem cells and their progeny. We found that radiation induced loss of Lgr5(+) stem cells in the colon, but not in the duodenum. Interestingly, the loss of colonic Lgr5(+) cells was compensated by de novo production of Lgr5(+) cells, which increased after irradiation. These findings show that ionizing radiation effectively stimulates the turnover of colonic Lgr5(+) stem cells, implying that radiation-induced damage does not accumulate in the colonic Lgr5(+) stem cells by this mechanism.

Quantitative analysis of biological responses to ionizing radiation, including dose, irradiation time, and dose rate.

Because biological responses to radiation are complex processes that depend on both irradiation time and total dose, consideration of both dose and dose rate is necessary to predict the risk from long-term irradiations at low dose rates. Here we mathematically and statistically analyzed the quantitative relationships between dose, dose rate and irradiation time using micronucleus formation and inhibition of proliferation of human osteosarcoma cells as indicators of biological response. While the dose-response curves did not change with exposure times of less than 20 h, at a given dose, both biological responses clearly were reduced as exposure time increased to more than 8 days. These responses became dependent on dose rate rather than on total dose when cells were irradiated for 20 to 27 days. Mathematical analysis demonstrates that the relationship between effective dose and dose rate is well described by an exponential function when the logarithm of effective dose is plotted as a function of the logarithm of dose rate. These results suggest that our model, the modified exponential (ME) model, can be applied to predict the risk from exposure to low-dose/low-dose-rate radiation.