Trends of Training Courses Conducted in the Human Resources Development Center of the National Institute for Quantum and Radiological Science and Technology After the Fukushima Dai-Ichi Nuclear Power Plant Accident.

Environmental contamination with radioactive materials caused by the Fukushima Dai-ichi Nuclear Power Plant (NPP) accident in 2011 raised a serious health concern among residents in Japan, and the demand for radiation experts who can handle the radiation-associated problems has increased. The Human Resources Development Center (HRDC) of the National Institute of for Quantum and Radiological Science and Technology in Japan has offered a variety of training programs covering a wide range of technologies associated with radiation since 1959. In this study, the time-course change in the number and age of the applicants for training programs regularly scheduled at HRDC were analyzed to characterize the demand after the NPP accident. The results suggested that the demand for the training of industrial radiation experts elevated sharply after the NPP accident followed by a prompt decrease, and that young people were likely stimulated to learn the basics of radiation. The demand for the training of medical radiation experts was kept high regardless of the NPP accident. The demand for the training of radiation emergency experts fluctuated apparently with three components: a terminating demand after the criticality accident that occurred in 1999, an urgent demand for handling of the NPP accident, and a sustained demand from local governments that undertook reinforcement of their nuclear disaster prevention program. The demand for the training of school students appeared to be increasing after the NPP accident. It could be foreseen that the demand for training programs targeting young people and medical radiation experts would be elevated in future.

Running exercise for short duration increases bone mineral density of loaded long bones in young growing rats.

Running exercise is an effective therapy for the prevention of osteoporosis; however, appropriate duration of exercise has not been determined. We therefore investigated the effect of exercise duration on bone mineral density (BMD) and systemic bone metabolism using young growing rats. Fifteen 8-week-old female Wistar rats were divided into three groups according to running load: control group (no running), short duration (30 min/day) and long duration (180 min/day), and animals ran on a treadmill 5 days per week over an 8-week period. BMD of the tibia was measured using peripheral quantitative computed tomography, and serum levels of tartarate-resistant acid phosphatase (TRAP), a bone resorption marker and alkaline phosphatase (ALP), a bone formation marker were measured to know whether the treadmill exercise would affect systemic bone metabolism. Short-duration running exercise (30 min/day) caused a significant increase in BMD of the metaphyseal trabecula (p < 0.05) with a reduction of serum TRAP levels (p < 0.01) and an increase in serum levels of calcium (p < 0.05) and phosphorus (p < 0.01). Conversely, long-duration exercise (180 min/day) significantly reduced BMD of the diaphyseal and metaphyseal cortex and that of the diaphyseal trabecula with a significant reduction of serum ALP levels and a significant increase in serum phosphorus. These findings suggest that short-duration exercise may increase BMD through suppression of bone resorption, whereas long-duration exercise may reduce BMD through suppression of bone formation. Exercising for short duration but not prolonged exercise is recommended to increase BMD of loaded long bones.

How many days per week should rats undergo running exercise to increase BMD?

The aim of the present study was to examine the effect of different frequencies of running exercise on increasing bone mineral density (BMD) and improving bone histomorphology at various sites of the skeleton (tibia, femur, and second lumbar vertebra) in young rats. Twenty-five female Wistar rats, 8 weeks old, were divided into five groups, of 5 animals each according to running load: control group, no running (A group); running load (RL), 4 days per week (d/w; B group); RL, 5 d/w (C group); RL, 6 d/w (D group); and RL, 7 d/w (E group). Rats ran on a treadmill at a speed of 15 m/min for 30 min per day over an 8-week period. The results indicated that the BMD of the tibia in the B, C, D, and E groups and that of the femur in the B and E groups increased significantly over that of the A group. However, the cortical BMD and trabecular BMD of the second lumbar vertebra did not change. In regard to bone histomorphometry of the tibia, a parameter of bone resorption (eroded surface/bone surface) was significantly lower in the B and D groups than in the A group. There were no differences in the parameters of bone formation. Tartaric acid-resistant acid phosphatase (TRACP) values were significantly lower in the B and C groups than in the A group. There were significant increases in body weight in the B group and in muscle weight in the C group. From the data obtained in this study, it was concluded that increases in BMD were obtained by a moderate running load at frequencies of 4 and 5 days per week.

Toxicity of uranium and the removal effects of CBMIDA and EHBP in simulated wounds of rats.

We examined the acute toxicity of uranium (99.3% 238U, 0.7% 235U) and the effects of Catechol-3,6-bis(methyleiminodiacetic acid) (CBMIDA) and Ethane-1-hydroxy-1,1-bisphosphonate (EHBP) on the removal of uranium after intramuscular injection as a simulated wound intake in rats. In this experiment, male Wistar rats, 8 wk old, were injected intramuscularly with uranyl nitrate in the femoral muscles. Experiment I: Rats died from 3 to 7 d after they were injected with five doses of 7.9, 15.8, 31.5, 63, and 126 mg kg(-1) uranium. The uranium retained 8.4-13.6% of the injected doses in the kidneys, showing the relationship between the injected dose and the retained concentration (r = 0.997). The excretion rates of the injected doses in the 63 and 126 mg kg(-1) uranium-injected rats were 1.73% and 3.09% in urine and 0.81% and 1.06% in feces on the first day, and 0.54% and 0.56% in feces on the second day, respectively. Experiment II: The retention of uranium at 1, 3, 6, and 24 h was examined after rats were injected with 63 mg kg(-1) uranium. The concentration of uranium decreased in the plasma, while it increased in the kidneys and femur until 6 h, and it continued to increase in the liver until 24 h. Experiment III: Rats were divided into four groups (n = 10) and were injected with a dose of 2 mg kg(-1) uranium. Two of the groups were then injected intraperitoneally with 240 or 480 mg kg-1 CBMIDA, and one group was injected with 10 mg kg(-1) EHBP once daily for 28 d, beginning 1 h after uranium injection on the first day. The fourth group was the non-treated control group. The survival rates at the end of the experiment were 80% and 40% in the 240 and 480 mg kg(-1) CBMIDA groups, 50% in the EHBP group, and 20% in the non-treated group. The successive administration of chelating agents was effective in decreasing the concentration of uranium in the kidneys, bone, and liver. The results indicated that uranium induces acute death and renal dysfunction by chemical toxicity, and both CBMIDA and EHBP were effective agents to prevent these effects.

Age-related changes in bone mineral density, cross-sectional area and the strength of long bones in the hind limbs and first lumbar vertebra in female Wistar rats.

Age-related changes in bone mineral density (BMD) and cross-sectional area and bone strength index (SSI) of the femur, tibia, humerus, and first lumbar vertebra in female Wistar (WM/MsNrs) rats were examined by a quantitative computed tomography (pQCT) method. One hundred and sixteen virgin female Wistar (WM/MsNrs) rats aged 2-33 months were used. The data indicate that the total BMD values of metaphyses and diaphyses of long bones increased until 12 months, then decreased to a varying degree depending on the bone after 15-24 months, but the values of cortical and trabecular BMD with age were not always similar to the total BMD value. Nevertheless, the values for cross-sectional area and SSI in the long bones increased regardless of the total BMD decrease with age, indicating that this increase might have been due to a characteristic of the modeling pattern in rats. The total and cortical BMD values in the first lumbar vertebra decreased after 18 months, and SSI did after 15 months. The data obtained in this study were compared with those obtained from males in a previous study. In conclusion, it was indicated that in this strain the rats over 12 months with the highest total BMD values in the femur and tibia, and before the onset of various tumors, are useful as a model animal for osteoporosis experiments and observation of senile bone change.

Age-related changes in blood pressure, hematological values, concentrations of serum biochemical constituents and weights of organs in the SHR/Izm, SHRSP/Izm and WKY/Izm.

Age-related changes in hematological values, serum biochemical constituents, and weights of various organs in both sexes of the Spontaneously Hypertensive (SHR/Izm), Stroke-prone SHR (SHRSP/Izm), and Wistar Kyoto (WKY/Izm) rat strains, bred under SPF conditions, were examined to obtain fundamental data. The body weights from 3-30 weeks and systolic blood pressure from 6-30 weeks in each strain were measured every week. At the ages of 8, 16, and 30 weeks, the hematological values (erythrocyte, hemoglobin, hematocrit, leucocyte, thrombocyte), serum biochemical constituents (total protein, GOT, GPT, ALP, BUN, creatinine, glucose, total Ca and phosphorus, and ionized Ca, Na, K, and Cl were measured. Also, the organs, brain, heart, lung, thymus, liver, spleen, pancreas, bilateral kidneys, adrenal glands, testes/ovaries, digestive tract, and muscle (soleus) were weighed. The age-related changes as well as the strain and sex differences in each measured item were examined. The body weights of each strain increased, but rate of the increase was less in SHR and SHRSP, and was lowest in SHRSP. The blood pressure of SHR and SHRSP elevated with age, and showed higher in SHRSP than SHR, while that of WKY did not change. There were many strain differences in most measured items at each time point, particularly at 30 weeks. In SHRSP, high values of BUN, creatinine, total and ionized Ca, weights of brain, heart, liver, kidney and digestive duct were observed at most time points indicating that this strain's abnormality of calcium metabolism may be related to functions of the kidney and digestive duct as well as hypertension.

Life span and spontaneous tumors incidence of the Wistar Mishima (WM/MsNrs) rat.

The life spans and spontaneous tumors in a total of 1960 Wistar Mishima (WM/MsNrs) rats, inbred strain, from the 80-130th generations were examined. The average life span (mean +/- SD) was 731 +/- 173 days (n = 1053) in the males and 813 +/- 214 days (n = 907) in the females (p < 0.0001). The average life span of tumor-afflicted females was significantly longer than that of the non-tumor group (p < 0.0001), while no such difference was observed in males. Tumors were observed in 33 males (3.1%) and 246 females (27.1%). In the males, tumors were often observed under the skin (2.2%). Frequencies of tumors in lung and liver, bones and intestine were less than 0.5%. In the females, incidence of mammary tumor was 20.1%, and various organs such as ovaries, uterus, bones, lung, and liver had tumor incidence frequencies of less than 3.5%. It was concluded that WM/MsNrs rats might be suitable for life span and age-related studies because of their characteristics of length of longevity and the low incidence of spontaneous tumors in both sexes.

Age-related changes in bone mineral density, cross-sectional area and strength at different skeletal sites in male rats.

Age-related changes in bone mineral density (BMD), cross-sectional area and strength strain index (SSI) of the long bones in the limbs and first lumbar vertebra of male Wistar rats were measured by a peripheral quantitative computed tomography (pQCT) method. One hundred and ten rats aged 2-30 months were used. The results indicate that the total (cortical + trabecular), cortical and trabecular BMD values of the metaphysis and cortical BMD values of the diaphysis in the long bones varied for each bone and differed from those of the first lumbar vertebra. The total BMD of long bones showed high values at 6-21 months and then decreased, but these did not always coincide with cortical and trabecular BMD. The values of SSI in the long bones varied. The values of total and cortical BMD and SSI of lumbar vertebra increased for 6-12 months and then decreased, but the trabecular BMD increased after 12 months. The total area in both the long bones and the first lumbar vertebra increased with the decrease in cortical area and the increase in the trabecular area with increasing age. It was concluded that age-related changes in bones, similar to those observed in humans, could be observed in some bones and parameters, although the age in rats when the so-called peak bone mass appears in the whole skeleton could not be clearly determined.

Preventive effects of running exercise on bones in heavy ion particle irradiated rats.

We examined the effects of running exercise on preventing decreases in bone mineral and tissue volume after heavy ion particle irradiation in rats. Male Wistar rats experienced whole-body irradiation by heavy ion particle beam (C-290 MeV) at doses of 0.5, 1.0, and 5.0 Gy and were divided into voluntary running groups and control groups. Rats in the running groups ran on the treadmill 15 m/min, 90 min/day for 35 days after exposure. At the end of the experiment, a tibia was obtained from each rat for measurement of bone mineral density (BMD) and cross-sectional area, strength strain index, and bone histomorphometric analysis. The weights of muscles and concentration of serum calcium were measured. Total BMD and trabecular BMD in the metaphysis and cortical BMD of the diaphysis of tibia in the running groups increased. Bone volume and trabecular thickness increased while trabecular separation decreased in the running groups compared to those in the control groups at respective doses. However, the osteoid surface and eroded surface varied in the running groups compared to those of the respective corresponding groups. The dynamic parameters such as mineralizing surface, mineral apposition rate, and bone formation rate in the running groups were varied, probably due to the differences in radiation-induced sensitivities of bones following radiation exposure. The overall results suggest that running exercise might have a beneficial effect on preventing bone mineral loss and changes in bone structure induced by space radiation, but it is necessary to examine the optimal conditions of running exercise response to doses.