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Volume 5, No 2 - Spring 2005

Volume 5, No 2 - Spring 2005

Table of Contents

Primary and Secondary Treatment for Helicobacter pylori in the United States
One of every 4 to 5 patients who receives antimicrobial therapy for Helicobacter pylori will not have successful eradication. Antimicrobial resistance, poor compliance with the antibiotic regimen, and drug-related side effects all play a role in determining the outcome of therapy. This article discusses the issues involved in H. pylori eradication, the mechanism of antibiotic delivery to the mucus layer of the stomach, and primary and secondary treatment strategies for H. pylori in the United States. [Rev Gastroenterol Disord. 2005;5(2):67-72]
Role of Extracorporeal Shock Wave Lithotripsy in the Treatment of Pancreatic Stones
Calcifications in chronic pancreatitis are usually the result of chronic inflammation or altered metabolism. Calcifications can perpetuate the cycle of ductal obstruction and contribute to pain, worsening of pancreatic inflammation, ductal disruption, and deterioration of the exocrine and endocrine function of the gland. Removal of pancreatic duct calculi can reduce pain and improve glandular function. Purely endoscopic stone removal has limited success, because of stone location, burden, and presence of strictures in the pancreatic duct. Extracorporeal shock wave lithotripsy (ESWL) allows fragmentation of stones refractory to endoscopic methods and facilitates spontaneous stone passage or endoscopic removal. Among the various forms of lithotripters, none is clearly superior to the others. Current data suggest that ESWL is effective in complete duct clearance in up to 50% of patients and in duct decompression and symptomatic improvement in up to 70% of patients. ESWL should be considered as a useful adjunctive tool in the treatment of pancreatic duct calculi. [Rev Gastroenterol Disord. 2005;5(2):73-81]
Environmental Versus Genetic Risk Factors for Irritable Bowel Syndrome: Clinical and Therapeutic Implications
The pathogenesis of irritable bowel syndrome (IBS) has traditionally been based on the biopsychosocial model that emphasizes that the symptom manifestations of IBS and consulting behavior are influenced at least in part by psychological processes. However, there has been increasing interest in trying to identify and unravel potential molecular mechanisms in IBS, and this endeavor has been driven by some evidence that there is a true genetic contribution to IBS. IBS does aggregate in families, and the concordance of IBS is twice as great in monozygotic compared with dizygotic twins in most, but not all, studies. A number of genetic polymorphisms have been associated with IBS but most remain to be independently confirmed, and unknown gene–environment interactions probably remain essential for the disorder to manifest. As we become better able to specify the phenotypes within IBS, it seems likely that increasingly relevant gene associations that have implications for testing and treatment will rapidly be identified. IBS probably represents a collection of several organic diseases, some of which may have a genetic component; the biopsychosocial model, although important, may represent a gross oversimplification of the underlying molecular pathogenesis. [Rev Gastroenterol Disord. 2005;5(2):82-88]
Adefovir Dipivoxil: Focus on Its Use in the Treatment of Chronic Hepatitis B
Adefovir is classified as a nucleotide reverse transcriptase inhibitor because it acts by inhibiting hepatitis B virus DNA polymerase (reverse transcriptase) and causing DNA chain termination after its incorporation into the viral DNA. Adefovir dipivoxil is indicated for the treatment of chronic hepatitis B in adults with evidence of active viral replication and either evidence of persistent elevations in serum aminotransferases (alanine [ALT] or aspartate [AST]) or histologically active disease. It is useful in the treatment of patients with either hepatitis B e antigen–positive or –negative chronic hepatitis B. The recommended adefovir dipivoxil dose in the treatment of chronic hepatitis B in patients with adequate renal function is 10 mg once daily. Adefovir dipivoxil therapy can reduce viral load, improve ALT, and produce histologic improvement in patients with chronic hepatitis B. Improvements are generally seen within the first few weeks of therapy and have shown persistence up to at least 3 years with continued therapy. Therapy with adefovir dipivoxil is generally well tolerated. However, nephrotoxicity is a risk with adefovir therapy, especially in patients receiving higher doses (30-120 mg/d). Patients should have their renal function monitored closely throughout therapy and may require an adjustment in dose relative to changes in the creatinine clearance. Lactic acidosis and severe hepatomegaly with steatosis may also occur during therapy. [Rev Gastroenterol Disord. 2005;5(2):89-100]