Prognostic impact of clinical outcome after endoscopic gastroduodenal stent placement for malignant gastric outlet obstruction: a multicenter retrospective cohort study using a time-dependent analysis.

Background: Endoscopic gastroduodenal stent (GDS) placement is widely used as a safe and effective method to rapidly improve gastrointestinal symptoms of malignant gastric outlet obstruction (MGOO). While previous studies reported the utility of chemotherapy after GDS placement for prognosis improvement, they did not fully address the issue of immortal time bias. Objectives: To examine the association between prognosis and clinical course following endoscopic GDS placement, using a time-dependent analysis. Design: Multicenter retrospective cohort study. Methods: This study included 216 MGOO patients who underwent GDS placement between April 2010 and August 2020. Data of patient baseline characteristics, including age, gender, cancer type, performance status (PS), GDS type and length, GDS placement location, gastric outlet obstruction scoring system (GOOSS) score, and history of chemotherapy before GDS were collected. The clinical course following GDS placement was evaluated by GOOSS score, stent dysfunction, cholangitis, and chemotherapy. A Cox proportional hazards model was used to identify prognostic factors after GDS placement. Stent dysfunction, post-stent cholangitis, and post-stent chemotherapy were analyzed as time-dependent covariates. Results: Mean GOOSS scores before and after GDS were 0.7 and 2.4, respectively, with significant improvement after GDS placement (p < 0.001). The median survival time after GDS placement was 79 [95% confidence interval (CI): 68-103] days. In multivariate Cox proportional hazards model with time-dependent covariates, PS 0-1 [hazard ratio (HR): 0.55, 95% CI: 0.40-0.75; p < 0.001], ascites (HR: 1.45, 95% CI: 1.04-2.01; p = 0.028), metastasis (HR: 1.84, 95% CI: 1.31-2.58; p < 0.001), post-stent cholangitis (HR: 2.38, 95% CI: 1.37-4.15; p = 0.002), and post-stent chemotherapy (HR: 0.01, 95% CI: 0.002-0.10; p < 0.001) significantly affected prognosis after GDS placement. Conclusion: Post-stent cholangitis and tolerability to receive chemotherapy after GDS placement influenced prognosis in MGOO patients.

A case of diaphragmatic hernia following colonoscopy.

An 89-year-old woman with a history of traumatic injury was referred to our hospital for further evaluation of anemia. Two days after colonoscopy, she complained of intermittent abdominal pain. An abdominal computed tomography confirmed a left diaphragmatic defect with a herniated transverse colon. She underwent elective laparoscopic repair of the diaphragmatic hernia. Colonoscopy rarely causes or worsens a diaphragmatic hernia. This is a rare case where we observed the development and exacerbation of a diaphragmatic hernia. It is important to pay attention to the development of a diaphragmatic hernia after colonoscopy for patients with a history of traumatic injury.

[Rupture of a pancreaticoduodenal artery aneurysm into the common bile duct secondary to chronic pancreatitis: a case report].

A 57-year-old man with a history of excessive drinking presented to our emergency department complaining of chest discomfort. He had been attending a clinic for diabetes mellitus and hypertension, at which he had been informed that he had anemia that was worsening. Computed tomography (CT) of the abdomen revealed hemobilia and chronic pancreatitis. Due to complicated cholangitis, endoscopic nasobiliary drainage was performed, and a contrast-enhanced abdominal CT scan showed a pancreaticoduodenal aneurysm close to the common bile duct. We diagnosed a ruptured pancreaticoduodenal artery aneurysm causing hemobilia, and performed selective transcatheter arterial embolization with intravascular microcoils. Complete occlusion of the aneurysm was confirmed on follow-up CT.

[Multiple gastrointestinal stromal tumors during nilotinib treatment for chronic myelogenous leukemia in a patient with neurofibromatosis type 1].

A 60-year-old woman with neurofibromatosis type 1 presented to our hospital with melena. She reported a 1-year history of treatment with nilotinib hydrochloride hydrate for chronic myelogenous leukemia. Contrast-enhanced abdominal computed tomography revealed multiple intestinal tumors that were subsequently diagnosed as gastrointestinal stromal tumors (GIST) using single-balloon enteroscopy. Although the tumors showed no significant change over 1 year, partial jejunal resection was performed to confirm the diagnosis. Immunohistochemically, the tumors were GIST.

Nucleostemin in injury-induced liver regeneration.

The high regenerative capacity of liver contributes to the maintenance of its size and function when injury occurs. Partial hepatectomy induces division of mature hepatocytes to maintain liver function, whereas severe injury stimulates expansion of undifferentiated hepatic precursor cells, which supply mature cells. Although several factors reportedly function in liver regeneration, the precise mechanisms underlying regeneration remain unclear. In this study, we analyzed expression of nucleostemin (NS) during development and in injured liver by using transgenic green fluorescent protein reporter (NS-GFP Tg) mice. In neonatal liver, the hepatic precursor cells that give rise to mature hepatocytes were enriched in a cell population expressing high levels of NS. In adult liver, NS was abundantly expressed in mature hepatocytes and rapidly upregulated by partial hepatectomy. Severe liver injury promoted by a diet containing 3,5-diethoxycarbonyl-1,4-dihydrocollidine induced the emergence of NS-expressing ductal epithelial cells as hepatic precursor cells. NS knockdown inhibited both hepatic colony formation in vitro and proliferation of hepatocytes in vivo. These data strongly suggest that NS plays a critical role in regeneration of both hepatic precursor cells and hepatocytes in response to liver injury.

Identification of tumor-initiating cells in a highly aggressive brain tumor using promoter activity of nucleostemin.

Controversy remains over whether the cancer stem cell (CSC) theory applies to all tumors. To determine whether cells within a highly aggressive solid tumor are stochastically or hierarchically organized, we combined a reporter system where the nucleostemin (NS) promoter drives GFP expression (termed NS-GFP) with a mouse brain tumor model induced by retroviral Ras expression on a p16(Ink4a)/p19(Arf)-deficient background. The NS-GFP system allowed us to monitor the differentiation process of normal neural stem/precursor cells by analyzing GFP fluorescence intensity. In tumor-bearing mice, despite the very high frequency of tumorigenic cells, we successfully identified the NS-GFP(+) cells as tumor-initiating cells (T-ICs). The clonal studies conclusively established that phenotypical heterogeneity can exist among the cells comprising a genetically homogeneous tumor, suggesting that this aggressive brain tumor follows the CSC model. Detailed analyses of the NS-GFP(+) brain tumor cells revealed that T-ICs showed activation of the receptor tyrosine kinase c-Met, which functions in tumor invasiveness. Thus, the NS-GFP system provides a powerful tool to elucidate stem cell biology in normal and malignant tissues.

Identification of stem cells during prepubertal spermatogenesis via monitoring of nucleostemin promoter activity.

The nucleostemin (NS) gene encodes a nucleolar protein found at high levels in several types of stem cells and tumor cell lines. The function of NS is unclear but it may play a critical role in S-phase entry by stem/progenitor cells. Here we characterize NS expression in murine male germ cells. Although NS protein was highly expressed in the nucleoli of all primordial germ cells, only a limited number of gonocytes showed NS expression in neonatal testes. In adult testes, NS protein was expressed at high levels in the nucleoli of spermatogonia and primary spermatocytes but at only low levels in round spermatids. To evaluate the properties of cells expressing high levels of NS, we generated transgenic reporter mice expressing green fluorescent protein (GFP) under the control of the NS promoter (NS-GFP Tg mice). In adult NS-GFP Tg testes, GFP and endogenous NS protein expression were correlated in spermatogonia and spermatocytes but GFP was also ectopically expressed in elongated spermatids and sperm. In testes of NS-GFP Tg embryos, neonates, and 10-day-old pups, however, GFP expression closely coincided with endogenous NS expression in developing germ cells. In contrast to a previous report, our results support the existence in neonatal testes of spermatogonial stem cells with long-term repopulating capacity. Furthermore, our data show that NS expression does not correlate with cell-cycle status during prepuberty, and that strong NS expression is essential for the maintenance of germline stem cell proliferation capacity. We conclude that NS is a marker of undifferentiated status in the germ cell lineage during prepubertal spermatogenesis.