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Pediatric minimally invasive surgery requires dexterous manipulation of surgical instruments to handle fragile tissues in a small and intricate workspace. Thus, pediatric surgeons need advanced surgical skills in order to avoid complications 1) ；however, junior pediatric surgeons have fewer opportunities to learn and practice these skills due to the limited number of pediatric patients compared to that of adult patients. Regardless of the limited number of pediatric patients, training of pediatric surgeons is very important as pediatric surgical outcomes can have a strong influence on the long-term quality of life of patients. To provide surgical skill assessment and training opportunities , several groups have developed simulators and models to replicate the conditions of pediatric minimally invasive surgery. For example, Azzie et al. proposed a pediatric laparoscopic surgery simulator using a miniature box trainer 2). Ieiri et al. developed a suture ligature model of the diaphragmatic crura in infant fundoplication 3). Barsness et al. developed a three-dimensional(3 D)-printed pediatric chest cavity model for training of pediatric thoracoscopic surgical skills 4). Harada et al. also developed a 3 Dprinted model replicating the chest cavity of a 1-year old patient with a force sensor placed inside its ribcage 5). These groups also conducted surgical skill assessments to show the validity of these simulators and models；the method typically used to demonstrate the validities of surgical simulators was described by Mason et al. 6) and is widely used, as shown in a survey by Ahmed et al. 7). In principle, there are subjective and objective validation methods. The construct validity is an objective validity

We have previously reported that oxy radicals can contribute to the enhancing effect of glycerol on 4-nitroquinoline 1-oxide (4NQO)-induced lung tumorigenesis in ddY mice. In this study, we established that feeding high doses of vitamin E to male ddY mice treated with 4NQO plus glycerol could reduce glycerol-enhanced lung tumorigenesis, due to the inhibition of glycerol-induced oxidative stress on the pulmonary nuclei. At 4 weeks after 4NQO injection (10 mg/kg, s.c.), the levels of nuclear thiobarbituric acid reactive substances and oxidative damage to DNA in the lungs of mice treated with 4NQO plus glycerol (5% solution as drinking water) were significantly higher than those in mice treated with 4NQO. The glycerol-induced increase was completely inhibited when a high vitamin E diet was provided for 4 weeks after 4NQO injection. As previously reported, at 23 weeks after 4NQO administration (at the end of this experiment), the 4 week treatment with glycerol enhanced 4NQO-induced lung tumorigenesis in ddY mice. In contrast, the supply of high doses of vitamin E at 4 and 23 weeks after 4NQO injection suppressed glycerol's ability to enhance lung tumorigenesis. These results suggest that vitamin E is useful in protecting against oxy radical-enhanced lung tumorigenesis in mice.

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