Phenotypic characterization of a new Grin1 mutant mouse generated by ENU mutagenesis

In the RIKEN large‐scale N‐ethyl‐N‐nitrosourea (ENU) mutagenesis project we screened mice with a dominant mutation that exhibited abnormal behavior in the open‐field test, passive avoidance test and home‐cage activity test. We tested 2045 progeny of C57BL/6J males treated with ENU and untreated DBA/2J females in the open‐field test and isolated behavioral mutant M100174, which exhibited a significant increase in spontaneous locomotor activity. We identified a missense mutation in the Grin1 gene, which encodes NMDA receptor subunit 1, and designated the mutant gene Grin1^Rgsc174. This mutation results in an arginine to cysteine substitution in the C0 domain of the protein. Detailed analyses revealed that Grin1^Rgsc174 heterozygote exhibited increased novelty‐seeking behavior and slight social isolation in comparison with the wild type. In contrast to other Grin1 mutant mice, this mutant exhibited no evidence of heightened anxiety. These results indicate that this is a unique behavioral Grin1 gene mutant mouse that differs from the known Grin1 mutant mice. The results of immunohistochemical and biochemical analyses suggested that impaired interaction between the glutamatergic pathway and dopaminergic pathway may underlie the behavioral phenotypes of the Grin1^Rgsc174 mutant.     

Effectiveness of basic endoscopic surgical skill training for pediatric surgeons

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.     

Thoracoscopic repair of neonatal left diaphragmatic hernia with sac combined with both extralobar pulmonary sequestration and congenital pulmonary airway malformation

Intradiaphragmatic extralobar pulmonary sequestration (IDEPS) is considered to be very rare among extralobar pulmonary sequestration (EPS), and IDEPS combined with congenital diaphragmatic hernia (CDH) with sac is extremely rare. The patient was a neonatal girl. Left-sided CDH with a hernia sac was diagnosed based on computed tomography (CT). Thoracoscopic repair was planned for the 5th day after birth. Left CDH with sac was recognized on the posterolateral side and isolated EPS was recognized on the sac. The hernia sac, including the EPS, was resected, and the diaphragm defect was closed. The resected specimen consisted of fibrous connective tissue and pulmonary sequestration (PS) connected with the sac. It was diagnosed as the hybrid form, with features of both type 2 congenital pulmonary airway malformation (CPAM) and EPS. The postoperative course was uneventful. At 1 year and 9 mo after the operation, no recurrence of herniation or laterality of the diaphragm was recognized.     

Role of endothelin‐1/endothelin receptor signaling in fibrosis and calcification in nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis (NSF) is characterized by systemic fibrosis and abnormal calcification in patients with severe renal dysfunction. It is considered that gadolinium (Gd)‐containing contrast agents used for magnetic resonance imaging trigger the development of NSF. However, the causative role of Gd and the mechanism of Gd‐induced fibrosis and calcification in NSF are unknown. Recently, it has been known that endothelin‐1 (ET‐1)/ET receptor (ETR) signalling regulates fibrosis and calcification. The objective was to elucidate the role of ET‐1/ETR signalling in Gd‐induced fibrosis and calcification in NSF. First, we demonstrated that Gd enhanced proliferation and calcification of human adipose tissue‐derived mesenchymal stem cells (hMSC) in vitro. Next, we examined the expression of ET‐1 and ETR‐A in hMSC using proliferation or calcification assay. ET‐1 and ETR‐A expression in hMSC treated with Gd were elevated. ET‐1/ETR signalling inhibitor, bosentan, inhibited Gd‐induced proliferation and calcification of hMSC. In addition, bosentan inhibited Gd‐induced phosphorylation of ERK and Akt in hMSC. Plasma ET‐1 levels of the patients were significantly higher than these of normal individuals and systemic sclerosis patients. In immunofluorescence staining, the expression of ETR‐A in fibroblasts in dermal fibrosis lesion of NSF was increased. We conclude that Gd induces proliferation and calcification of hMSC via enhancement of ET‐1/ETR signalling. Our results contribute to understand the pathogenesis of NSF.