Hiroyuki Sagawa

Connexin 32 and luteolin play protective roles in non-alcoholic steatohepatitis development and its related hepatocarcinogenesis in rats

Non-alcoholic steatohepatitis (NASH) has the potential to lead to the development of cirrhosis and hepatocellular carcinoma (HCC). Connexin (Cx) 32, a hepatocyte gap-junction protein, plays a preventive role in hepatocarcinogenesis. However, the precise contribution of Cx32 in the development of NASH has not been established. In this study, we aimed to clarify the role of Cx32 and the chemopreventive effect of luteolin, an antioxidant flavonoid, on the progression of NASH and NASH-related hepatocarcinogenesis. Cx32 dominant negative transgenic (Cx32ΔTg) and wild-type (Wt) rats at 10 weeks of age were given diethylnitrosamine and fed methionine-choline-deficient diet (MCDD) or MCDD with luteolin for 12 weeks. MCDD induced steatohepatitis and fibrosis along with increased inflammatory cytokine expression and reactive oxygen species in the liver. These effects were more severe in Cx32ΔTg rats as compared with Wt rats, and significantly suppressed by luteolin in both genotypes. Concerning NASH-related hepatocarcinogenesis, the number of glutathione S-transferase placental form (GST-P)-positive foci was greater in Cx32ΔTg versus Wt rats, and significantly reduced by luteolin in Cx32ΔTg rats. Microarray analysis identified brain expressed, X-linked 1 (Bex1) as an upregulated gene in Cx32ΔTg rat liver. Quantitative RT-PCR and in situ hybridization revealed that increased Bex1 mRNA was localized in GST-P-positive foci in Cx32ΔTg rats, and the expression level was significantly decreased by luteolin. Moreover, Bex1 knockdown resulted in significant growth inhibition of the rat HCC cell lines. These results show that Cx32 and luteolin have suppressive roles in inflammation, fibrosis and hepatocarcinogenesis during NASH progression, suggesting a potential therapeutic application for NASH.

Connexin 32 dysfunction promotes ethanol-related hepatocarcinogenesis via activation of Dusp1-Erk axis

There is abundant epidemiological evidence that heavy alcohol intake contributes to hepatocellular carcinoma (HCC) development. Previous reports indicated that connexin 32 (Cx32), which is a major hepatocyte gap junction protein, is down-regulated in chronic liver disease and has a protective role in hepatocarcinogenesis. However, functions of Cx32 in alcohol-related hepatocarcinogenesis have not been clarified. To evaluate them, 9-week-old Cx32 dominant negative transgenic (Tg) rats and their wild-type (Wt) littermates were given 1 % or 5 % ethanol (EtOH) or water ad libitum, for 16 weeks after an intraperitoneal injection of diethylnitrosamine (200 mg/kg). EtOH significantly increased the incidence and multiplicity of HCC and total tumors in a dose-dependent manner in Tg rats, but not in Wt rats. Although the number and area of glutathione S-transferase placental form (GST-P) positive foci were not significantly different between the groups, EtOH increased the Ki-67 labeling indices in GST-P positive foci only in Tg rats. EtOH up-regulated phosphorylated Erk1/2 with decrease of the Erk1/2 inhibitor, dual specificity protein phosphatase 1 (Dusp1) in whole livers of Tg and Wt rats. Immunofluorescence staining and quantitative RT-PCR revealed that EtOH significantly increased nucleolar localization of phosphorylated Erk1/2 and contrastingly reduced Dusp1 protein and mRNA expression in GST-P positive foci and HCC of Tg rats as compared to those of Wt rats. These findings suggest that Cx32 dysfunction like in chronic liver disease promoted EtOH-associated hepatocarcinogenesis through dysregulation of Erk-Dusp1 signaling.

Laparoscopically resected obturator nerve schwannoma: A case report.

Obturator nerve schwannomas are very rare. To date, only nine cases have been reported in the English‐language literature; none of these were diagnosed preoperatively. A 68‐year‐old woman was admitted with left lower abdominal pain. CT and MRI revealed a mass 30 mm in diameter in the left obturator fossa, suggesting a retroperitoneal tumor. Because CT and MRI revealed clear continuity with the left obturator nerve, this case was diagnosed as an obturator nerve schwannoma. Tumor enucleation was performed by laparoscopy. On histopathological examination, this case was diagnosed as a benign obturator nerve schwannoma. Postoperatively, the patient developed weakness of the adductor muscle but recovered within 6 months with rehabilitation therapy. Preoperative diagnosis of obturator nerve schwannomas is quite difficult, but careful inspection of CT and MRI is important to identify the original nerve of schwannoma preoperatively. Accordingly, laparoscopic resection is a good treatment option.

Profiling Surgical Staplers: Does Staple Direction Affect the Strength of the Anastomosis?

Background: Few studies have been conducted regarding the optimal staple direction in gastrointestinal anastomosis. The purpose of this study was to evaluate the burst pressure of the anastomosis depending on the firing direction of the stapler. Methods: Pig esophagus and small bowel were used for all experiments. The small intestine represented a thin intestinal tract and the esophagus represented a thick intestinal tract. A side-to-side anastomosis was performed using a linear stapler, and the burst pressure was measured. A leak test on the anastomosis was then performed and burst pressures measured. Results: Burst pressures after anastomosis using a GIA™ 100-3.8 were 47.4 ± 10.4 mm Hg. With the same GIA, the burst pressure was significantly greater when the staples were driven from the small intestine into the esophagus (83.3 ± 17.3 mm Hg). Using the GIA™ 100-4.8, it was found that the burst pressure was significantly greater when the staplers were driven into the small intestine versus the esophagus (51.6 ± 7.1 vs. 68.6 ± 16.1 mm Hg). There was no significant difference between the different GIAs when fired in the same direction. Conclusion: Burst pressures were significantly greater when the staplers were driven from the small intestine into the esophagus. The direction of the staple line influences the strength of the anastomosis.