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Purpose: Lack of ganglion cells is the main cause of bowel movement disorder in Hirschsprung's disease. Because smooth muscle is the primary organ, the properties of intestinal smooth muscle need to be investigated. We therefore investigated the reactivity of the contractile system and the mechanism of contraction in aganglionic intestinal smooth muscle.Methods: Colonic smooth muscle strips from endothelin-B receptor gene-deficient [EDNRB(-/-)] rats were loaded with the Ca(2+) indicator dye fura-PE3/AM and changes in fluorescence intensity were monitored. The intracellular calcium concentration ([Ca(2+)]i) and force development in the strips were measured simultaneously.Results: The force induced by 10 microM substance P (SP) was higher than that induced by 60 mM K(+) depolarization (control), whereas [Ca(2+)]i elevation induced by 10 microM SP was less than that induced by 60 mM K(+) in all segments. Pretreatment with the Rho-kinase inhibitor Y-27632 inhibited force development more strongly in EDNRB(-/-) aganglionic segments than in EDNRB(+/+) ganglionic segments. However, [Ca(2+)]i was higher in EDNRB(-/-) aganglionic segments than in EDNRB(+/+) ganglionic segments.Conclusions: The Ca(2+)-independent pathway involving Rho-kinase was hyperactivated in EDNRB(-/-) aganglionic segments. This phenomenon is assumed to compensate for Ca(2+) channel downregulation and Ca(2+)-dependent contraction. From a clinical point of view, the motility of aganglionic intestine would be controllable with the control of Ca(2+)-independent contraction before definitive operations in Hirschsprung's disease. [ABSTRACT FROM AUTHOR]

Purpose: Pediatric surgeons require highly advanced skills when performing endoscopic surgery, but their experience with such cases tend to be limited in comparison to general surgeons. The aim of this study was to evaluate the effectiveness of basic endoscopic surgery training for less-experienced young pediatric surgeons and then compare their skills with those of general surgeons.Methods: The surgeons (n = 477) subjected to this study underwent a 2-day endoscopic skill training program, consisting of lectures, box training, VR simulator training, tissue training, and live tissue training. The trainees were divided into two groups: P (pediatric surgeons, n = 33) and G (general surgeons, n = 444). The trainees were required to make a continuous suture along a circle measuring 2.5 cm in diameter and the findings were evaluated both before and after training. A statistical analysis was conducted using the unpaired t test.Results: The number of experienced cases totaled 20.8 ± 23.9 in P and 60.6 ± 80.5 in G (p < 0.001). The number of completed sutures before training was 1.4 ± 1.1 in P and 1.9 ± 1.5 in G (p < 0.05). The number of completed sutures after training was 4.1 ± 1.3 in P and 3.9 ± 1.9 in G (p > 0.05). The economy and speed of the forceps improved, however, the number of errors increased.Conclusion: Less-experienced pediatric surgeons improved their surgical skill and ability until reaching almost the same level as that observed in more experienced general surgeons during training, however, the number of errors after training increased in comparison to before training. As a result, this program needs to be modified to reduce the number of errors while enabling pediatric surgeons to master the safe and precise surgical techniques needed in this field. [ABSTRACT FROM AUTHOR]