Ajaypal Singh

Radiation exposure in gastroenterology: improving patient and staff protection.

Medical imaging involving the use of ionizing radiation has brought enormous benefits to society and patients. In the past several decades, exposure to medical radiation has increased markedly, driven primarily by the use of computed tomography. Ionizing radiation has been linked to carcinogenesis. Whether low-dose medical radiation exposure will result in the development of malignancy is uncertain. This paper reviews the current evidence for such risk, and aims to inform the gastroenterologist of dosages of radiation associated with commonly ordered procedures and diagnostic tests in clinical practice. The use of medical radiation must always be justified and must enable patients to be exposed at the lowest reasonable dose. Recommendations provided herein for minimizing radiation exposure are based on currently available evidence and Working Party expert consensus.

Adverse events associated with percutaneous enteral access.

Placement of percutaneous endoscopic gastrostomy or jejunostomy is a safe procedure with low periprocedural mortality, but overall mortality rates are high because of underlying disease conditions. These procedures are also associated with postprocedure complications. The clinically significant adverse events related to the procedures include infection (at tube site and peritonitis), bleeding, and aspiration. More rare associated events include buried bumpers, injury to adjacent viscera with subsequent fistula formation, and tumor seeding. There is a lack of guidelines about these procedures other than those concerning the use of antibiotics and the management of antithrombotics and anticoagulation before the procedure.

The Role of Endoscopy in the Diagnosis and Management of Cholangiocarcinoma.

Cholangiocarcinomas (CCAs) are associated with poor overall survival, and majority of the tumors are unresectable at the time of diagnosis. Early diagnosis at a resectable stage is essential for improved outcomes. Noninvasive imaging plays an important role in evaluating patients with biliary obstruction, but is limited due to the lack of tissue sampling and in many cases due to the absence of a mass, especially for extrahepatic CCAs. Endoscopic diagnosis is needed in majority of patients with CCA and the diagnostic yield depends on the tumor location as well as the expertise and experience of the endoscopist. Endoscopic retrograde cholangiopancreatography and endoscopic ultrasound remain the most common endoscopic diagnostic tools although newer technologies including fluorescence in situ hybridization, single-operator cholangioscopy, confocal laser endomicroscopy, and intraductal ultrasound are being increasing used. Traditionally, the role of endoscopy has been mainly palliative and limited to biliary drainage in patients with obstructive jaundice, however, newer treatment options like photodynamic therapy and radiofrequency ablation have shown promise toward improved patient survival. Multidisciplinary approach that involves medical oncology, gastroenterology, radiology, and surgical oncology teams is imperative for improved outcomes. In this review, we will first review the diagnostic approach to CCAs including imaging and endoscopic methods followed by a discussion of different endoscopic techniques in management of patients after a diagnosis of CCA.

Advances in the management of Barrett's esophagus and early esophageal adenocarcinoma

The incidence of esophageal adenocarcinoma (EAC) has markedly increased in the United States over the last few decades. Barrett’s esophagus (BE) is the most significant known risk factor for this malignancy. Theoretically, screening and treating early BE should help prevent EAC but the exact incidence of BE and its progression to EAC is not entirely known and cost-effectiveness studies for Barrett’s screening are lacking. Over the last few years, there have been major advances in our understanding of the epidemiology, pathogenesis and endoscopic management of BE. These developments focus on early recognition of advanced histology and endoscopic treatment of high-grade dysplasia. Advanced resection techniques now enable us to endoscopically treat early esophageal cancer. In this review, we will discuss these recent advances in diagnosis and treatment of Barrett’s esophagus and early esophageal adenocarcinoma.

Use of narrow-band imaging with magnification to predict depth of invasion of early esophageal squamous cell cancer and to guide endoscopic therapy

A 77-year-old man undergoing EGD for Barrett’s surveillance was noted to have an area of discolored mucosa with mild nodularity in the upper esophagus. A biopsy sample taken from the lesion showed high-grade squamous dysplasia. Repeat endoscopy using narrow-band imaging (NBI) with magnification (GIF-HQ190 with integrated dual-focus magnification, Olympus Optical, Tokyo, Japan) showed a well-demarcated area with intraepithelial papillary capillary loop (IPCL) dilatation, elongation, and mild irregularity along with background color change (A). No neovascularization or avascular areas were noted. Lugol chromoendoscopy of this lesion did not stain. Based on the IPCL changes, we classified the lesion as type V2 per Inoue’s classification and type 3 per Arima’s classification. According to published data from Japan, both classes predict the cancer to be either

Endoscopic or Minimally Invasive Debridement of Walled-Off Pancreatic Necrosis?

Acute necrotizing pancreatitis comprises 10–15 % of acute pancreatitis cases but is associated with significant mortality of around 15 % that further increases up to 30 % if the necrotic tissue becomes infected. Historically, open surgical debridement has been the most common intervention but over the last two decades various minimally invasive modalities have been developed including percutaneous, endoscopic, laparoscopic, retroperitoneal debridement or combinations of the above. Due to constantly evolving nature of minimally invasive techniques and lack of consensus definition of the collections in the past, there is a lack of prospective data comparing the different interventions. Our understanding of the pancreatic fluid collections has improved and a standardized classification of pancreatic and peripancreatic fluid collections was recently proposed in the form of revised Atlanta Classification in 2012. Now conclusive evidence exists that minimally invasive techniques are associated with lower morbidity and mortality compared to open surgical debridement. Amongst the minimally invasive techniques, endoscopic debridement is associated with lower morbidity compared to laparoscopic or retroperitoneal approaches though mortality benefit is not clear and long-term outcomes data is lacking. Step up approach allows for more aggressive interventions only in patients failing conservative therapy or percutaneous drainage and hence can prevent aggressive and morbidity associated debridement procedures in a fraction of symptomatic walled-off necrosis patients.

Barrett’s Esophagus: Treatment Options

Barrett’s esophagus (BE) is an asymptomatic condition, but it is the most significant known risk factor for the development of esophageal adenocarcinoma (EAC). More than half of short segment BE patients do not have any reflux symptoms. Cancer develops in BE through a sequence of genetic and epigenetic changes that activate oncogenes and silence tumor suppressor genes and cause progression from metaplasia through dysplasia to esophageal adenocarcinoma. Treatment approaches to BE mainly focus on eradication of high-grade dysplasia and neoplasia as well as prevention of progression of metaplasia to neoplasia. The treatment options for BE have undergone a significant change over the last few years due to improvement in our understanding of pathogenesis and progression of Barrett’s esophagus as well as availability of endoscopic treatment modalities.

Su1992 TNF Mediates β-Catenin Activation in Intestinal Stem Cells During Colitis

G A A b st ra ct s in colonoid culture and we posit that activation of the TRIF signaling pathway is the main mediator of these changes. Understanding how innate immune recognition pathways crosstalk with epithelial stem cell self-renewal and differentiation pathways will be important for future studies examining the role of stem cells in homeostasis and tumor promotion. We would like to acknowledge the technical help and provision of reagents by Richard J. von Furstenberg and Susan J. Henning.

S1653 IL- 6 Contributes to Epithelial Stem Cell Activation During Chronic Colitis

tions involved in the development of intestinal inflammation. Here we investigated whether high fat diet-induced obesity alters the course of trinitrobenzene sulfonic acid (TNBS) induced colitis and evaluated the extent of mesenteric fat depot involvement. Methods: Male C57BL/ 6 mice were divided into four groups (n=8). Groups 1 and 2 were kept on regular diet and groups 3 and 4 on high fat diet (HFD) for six weeks. After six weeks groups 2 and 4 received intracolonic TNBS (100 mg/kg), while groups 1 and 2 received vehicle. Protein and RNA were isolated from mesenteric fat depots and intestine. Myeloperoxidase (MPO) activity was measured on adipose tissue protein lysates. H & E stained mesenteric fat tissue sections were examined. Results: Light microscopic analysis in TNBS-exposed mice showed higher levels of inflammatory cell infiltrates in the intestine and adipose tissue and increased colonic histological damage in HFD-treated obese mice compared to all other groups. MPO activity was elevated in fat and intestine from TNBS treated animals under both dietary conditions (p<0.05), but significantly higher in the tissues isolated from high fat-fed animals (p<0.01). Furthermore, obesity also increased mRNA expression of the proinflammatory cytokines IL1β, TNFα, MCP-1 and KC, (p<0.001 for adipose and p<0.05 for intestine) while it reversed the TNBS-induced increases in IL-2 and IFNγ (two cytokines involved in T-cell maturation, p<0.05) in both adipose and intestinal tissues. Conclusions: Our data suggest a strong correlation between preexisting obesity and the degree of acute experimental colitis. Overall, our results may reflect conditions that are important for the pathophysiology of inflammatory bowel disease (IBD). Supported by a Research Fellowship from CCFA to JK and NIH grant DK47343 to CP.