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Volume 7, No 1 - Winter 2007

Volume 7, No 1 - Winter 2007

Table of Contents

The A’s and B’s of Vaccine-Preventable Hepatitis: Improving Prevention in High-Risk Adults State-of-the-Art Review
Acute hepatitis A and acute hepatitis B are associated with significant morbidity, time away from work or usual activities, substantial cost to the healthcare system, and some mortality. Despite the availability of vaccines against hepatitis B and hepatitis A since 1981 and 1995, respectively, and a combined hepatitis A and B vaccine since 2001, immunization rates against these vaccine-preventable diseases are appallingly low. In particular, several groups of adults, such as men who have sex with men, heterosexuals with multiple partners, injection drug users, persons with human immunodeficiency virus infection, travelers to endemic areas, and persons with chronic liver disease, are at particularly high risk for acute hepatitis A and B or for a more severe illness or a higher rate of chronicity in the case of hepatitis B. Studies have confirmed that hepatitis A and hepatitis B vaccines are safe and immunogenic in patients in these populations, although patients with more advanced disease may respond less well. These observations have led to the recommendation that patients falling into the above risk groups undergo hepatitis A and B vaccination early in the natural history of their underlying risk behavior or diseases. Vaccination rates are low in clinical practice, and public health and educational programs are needed to overcome barriers to facilitate timely implementation of these recommendations. The use of a combined vaccination, possibly using an accelerated administration schedule, provides convenience and may increase compliance. [Rev Gastroenterol Disord. 2007;7(1):1-21]
Endoscopic Ultrasound and Percutaneous Access for Endoscopic Biliary and Pancreatic Drainage After Initially Failed ERCP State-of-the-Art Review
Although the success rates of endoscopic retrograde cholangiopancreatography (ERCP) in accessing the bile and pancreatic ducts are quite high, failure to achieve duct access still occurs. Options in these cases have traditionally included percutaneous access or open surgical intervention. A combination percutaneous and endoscopic approach (ie, rendezvous procedure) is often used in cases of failed biliary cannulation by ERCP and occasionally for pancreatic duct access. However, this technique often results in complications and is hampered by the difficulty in coordinating schedules between interventional radiologists and endoscopists and the lack of predictability of failed ERCP access. Several groups have described the use of endoscopic ultrasonography (EUS) in accessing the ducts in cases of failed ERCP. This technique has the potential to substantially reduce the need for a percutaneous or surgical approach in many cases. This article reviews the nonsurgical methods for accessing the biliary and pancreatic ducts after failure of ERCP as well as the current status and possible future applications of EUS-assisted drainage techniques. [Rev Gastroenterol Disord. 2007;7(1):22-37]
Natalizumab: Overview of Its Pharmacology and Safety New Drug Review
Natalizumab is a humanized monoclonal antibody that is produced in murine myeloma cells. It functions in the body as an antagonist of integrin heterodimers that contain the a4 integrin subunit. These heterodimers include a4ß1 integrin and a4ß7 integrin, which are expressed on the surface of most leukocytes. When natalizumab binds to the a4-subunit of the integrin, it prevents the a4-mediated adhesion of the leukocytes to their counter-receptor(s) (eg, vascular cell adhesion molecule-1 and mucosal addressin cell adhesion molecule-1), thus preventing transmigration of the leukocytes across the endothelium and into the inflamed parenchymal tissue. Clinical trials with natalizumab for the treatment of the relapsing forms of multiple sclerosis have found the drug is capable of delaying the accumulation of physical disability and reducing the frequency of clinical exacerbations. Clinical trials of natalizumab for the treatment of Crohn’s disease have found the drug, alone or in combination with infliximab, is effective in improving clinical response and remission rates as well as health-related quality of life in patients with Crohn’s disease who have not been able to achieve remission with infliximab therapy alone. Like all drugs, natalizumab is not without risks. The drug was temporarily withdrawn from the market because of 3 reported cases of progressive multifocal leukoencephalopathy. Subsequent evaluations determined that the risk of this severe, but rare, adverse reaction did not justify keeping the drug off the market. When natalizumab was reintroduced, however, a closed prescribing and distribution program (Tysabri Outreach Unified Commitment to Health [TOUCH™]) was also introduced. This program requires all patients prescribed natalizumab to be enrolled in and to receive their medication through the TOUCH system. Any serious adverse reactions must be reported to the TOUCH and MedWatch systems. [Rev Gastroenterol Disord. 2007;7(1):38-46]
Advances in Liver Disease Meeting Review
Highlights from the 57th Annual Meeting of the American Association for the Study of Liver Diseases, October 27-31, 2006, Boston, MA [Rev Gastroenterol Disord. 2007;7(1):47-58]