ABSTRACT
Objective:To investigate whether ultra-high dose rate (FLASH) irradiation can reduce radiation-induced intestinal injuries of mice compared to conventional dose rate (CONV) irradiation.Methods:Both FLASH and CONV irradiation were delivered with electron beam, with dose rates of 750 Gy/s and 0.5G y/s, respectively. A total of 105 mice were randomly divided into groups using a simple randomization method. Twenty-one mice were selected for weight observation, 7 mice in each group. After 9 Gy FLASH and CONV irradiation on the abdomen, the weight changes of mice were measured every other day, and compared among three groups. Twenty-four mice were selected for pathological examination including 5 mice in the control group. Three-and-a-half-day days after 12 Gy FLASH ( n=10) and CONV irradiation ( n=9) on the abdomen, the intestines of the mice were taken. Pathological sections were stained with hematoxylin-eosin (HE) to compare the number and percentage of regenerated crypts of the small intestine between two groups. After 12 Gy FLASH ( n=10) and CONV irradiation ( n=10) on the abdomen, the survival of 20 mice was observed. After FLASH using 4.5 Gy×2 times ( n=10) and CONV irradiation at 9 Gy×1 time ( n=10) on the abdomen, the weight changes were observed. After FLASH using 6 Gy×2 times ( n=10) and CONV irradiation at 12 Gy×1 time ( n=10) on the abdomen, the survival of mice was observed. The time interval between two irradiation was 1 min. EBT3 film was employed to monitor the actual exposure dose of the mice. The variables conforming to normal distribution were expressed by Mean±SD. Inter group comparison was performed by independent t-test. The survival of mice among different groups was compared by log-rank test. Results:After 9 Gy of abdominal irradiation, the mean weight of mice in the FLASH group was significantly higher than that in the CONV group. The weight of mice in the FLASH and CONV groups was (19.8±0.8) g and (18.0±1.8)g ( P=0.036) at 7 days after irradiation, (22.0±1.0)g and (21.2±0.5)g ( P=0.075) at 15 days after irradiation, and (24.2±1.4)g and (22.0±1.2)g ( P=0.012) at 25 days after irradiation, respectively. After 12 Gy irradiation, the mean survival of mice in FLASH and CONV groups was 4 days and 4.7 days ( P=0.029). After 12 Gy total abdominal irradiation, the mean number of intestinal regenerative crypts in the FLASH and CONV groups was 2.9/mm and 1.2/mm ( P=0.041), and the percentage of intestinal regenerative crypts was 34.1% and 14.1%, respectively. The survival of mice irradiated by FLASH using 6 Gy×2 times was longer compared with that of mice after CONV irradiation at 12 Gy×1 time. The weight of mice after 4.5 Gy×2 times irradiation was higher than that of mice after CONV irradiation at 9 Gy×1 time. Conclusion:Weight, survival and the number of intestinal regenerative crypts in the FLASH group are higher than those in the CONV group after irradiation, indicating that radiation-induced intestinal injury caused by FLASH irradiation is slighter than that of CONV irradiation.
ABSTRACT
Objective To evaluate the appropriateness of hospitalization days at a tertiary hospital in 2014 by means of the Appropriateness Evaluation Protocol ( AEP ) , and to analyze the causes of inappropriate stays. Methods Medical records of inpatients admitted at a tertiary hospital in 2014 were randomly selected. AEP( US version) was used to evaluate the appropriateness of every hospitalization day, while the causes of inappropriate hospitalization day were also analyzed. Results A total of 1 641 days of stay from 148 medical records were reviewed, and 129 days of stay (7. 9%) were seen as inappropriate. Two major factors for inappropriate stays were waiting for surgery and waiting for test, roughly 89. 1% of the inappropriate hospitalization days. The proportion of inappropriate hospital stays reduced to 4. 8% after adjustment of two-day weekend. Inappropriate hospital stays mostly appeared during the second day to the eighth day after admission(93. 8%). Logistic analysis results showed that with concomitant symptoms, preoperative waiting days > 5 days, high level surgery, non-emergency admission were significantly associated with appropriateness of hospital stays (P<0. 05). Conclusions The rate of inappropriate stays will be reduced and the quality of medical services will be improved if comprehensive measures could be carried out according to the causes of inappropriate stays.
ABSTRACT
Objective This study was aimed to investigate the expression of monocyte chemoattractant protein-1 (MCP-1) and vascular endothelial growth factor (VEGF) mRNA in rats with acute methanol poisoning. Methods Animal models of acute methanol poisoning in rats were duplicated using a plexiglas chamber exposed to a mixture of N2O/O2. Right atrium venous blood of rats were taken at each time point (2 h, 12 h, 24 h,3 d,1 w), and gas chromatography was used to determine the methanol concentration of the rat blood (n=5) . Then got brain tissue to extract total RNA and reverse transcription (n=3) . SYBRGreen real-time PCR was used to monitor the expression of MCP-1 and VEGF mRNA. Results (1) Results of methanol concentration determination:The blood methanol concentration of the low-dose group was significantly increased in comparison with that of the saline control group at 2 h and 12 h time points ( < 0.05) . In the high-dose group, the blood methanol concentration was increased significantly compared with the low-dose group as well as the saline group at 2 h, 12 h and 24 h time points ( < 0.05); (2) The expression of MCP-1 mRNA: The expression level of MCP-1 were significantly enhanced along with the time lapse after acute poisoning,and became most severely at 24 h. The expression levels of MCP-1 have significant differences in groups,of which high-dose group was higher than low-dose group at 2 h, 3 d and 1 w ( <0.05);(3) The expression of VEGF mRNA:The expression level of VEGF was significantly enhanced along with the time lapse after acute poisoning,and became most severely at 24 h. The expression levels of MCP-1 have significant differences in groups,of which high-dose group was higher than low-dose group at 2 h and 12 h ( <0.05) . Conclusion The expression levels of MCP-1 and VEGF mRNA were significantly enhanced, and the degree of poisoning was apparently related with the dose administered. MCP-1 and VEGF might play the important roles in the pathogenesis and progression of brain injured.