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Biomedical subjects

Paul L Beck

Publications and source records attributed to Paul L Beck.

12 recordsLinked to original sources
PubMed2005

Helicobacter pylori eradication: novel therapy for immune thrombocytopenic purpura? A review of the literature.

Eradication of Helicobacter pylori (H. pylori ) from the gastric mucosa has been associated with improvement of several systemic diseases, including immune thrombocytopenic purpura (ITP). Over the last 5 years, several studies have reported improved platelet counts in H. pylori-positive ITP patients following standard triple H. pylori eradication therapy. Review of published studies in which eradication of H. pylori has been performed in the ITP population indicates an overall response rate of 52% in 193 subjects in whom H. pylori was eradicated. Cohorts from Japan and Italy report higher response rates. There is no established mechanism to explain how this organism, which does not invade the gastric mucosa, could be implicated in the pathogenesis of this immune-based platelet disorder. Several theories including molecular mimicry, platelet aggregation, and immunomodulatory effects of macrolides have been proposed to explain the platelet response to anti-H. pylori therapy. Large randomized-controlled studies enrolling patients from various ethnic backgrounds will be necessary to determine the response rate and mechanism of response and to gain a better understanding of the pathogenesis of ITP.

Anti-Bacterial Agents↗
PubMed2005

CD154-CD40 interactions drive hepatocyte apoptosis in murine fulminant hepatitis.

The CD154-CD40 interaction is a critical costimulatory pathway modulating the cellular immune response. Moreover, fulminant hepatitis of various etiologies is characterized by a hepatic influx of CD154-expressing T cells and an upregulation of CD40 expression on Kupffer cells and hepatocytes, implicating this pathway in the pathogenesis of fulminant hepatitis. In this study, we used a murine model of fulminant hepatitis induced by concanavalin A (con A) and documented a significant influx of CD154-expressing T cells into the livers of mice treated with con A, in association with markedly increased expression of CD40 restricted mainly to hepatocytes in damaged areas of the liver. Furthermore, con A hepatitis in CD154-deficient mice was significantly attenuated compared with that in wild-type controls and was associated with a decrease in hepatic tumor necrosis factor alpha (TNF-alpha) levels and hepatocyte death. We next determined the role of the CD154-CD40 pathway in hepatocyte death in vitro. These in vitro studies demonstrated that TNF-alpha induces CD40 expression in hepatocytes and that subsequent activation of CD40 results in hepatocyte apoptosis mediated at least in part by enhanced hepatocyte expression of FasL. In conclusion, CD154 stimulation of CD40 plays a central role in hepatocyte death in fulminant hepatitis through direct and indirect pathways that may have direct therapeutic implications in humans. Supplementary material for this article can be found on the HEPATOLOGY website (http://interscience.wiley.com/jpages/0270-9139/suppmat/index.html).

Animals↗
PubMed2004

Celiac disease. CME update for family physicians.

OBJECTIVE: To review current understanding of the epidemiology, pathophysiology, diagnosis, and management of celiac disease. QUALITY OF EVIDENCE: Few recent randomized controlled trials (level I evidence) have studied treatments for celiac disease. There are recent comparative studies (level II evidence) and there is well established consensus (level III evidence) on diagnosis and treatment of celiac disease. MAIN MESSAGE: Celiac disease is an immune-mediated small bowel enteropathy caused by exposure to wheat gluten protein. The disease can be insidious and often presents with only subtle extraintestinal manifestations in a variety of organ systems. Recent epidemiologic surveys suggest celiac disease is much more common in North America than previously thought. Advances in immunology and screening have made diagnosis more reliable than in the past. Removing gluten from the diet is effective in most cases. CONCLUSION: Celiac disease manifests subtly and is an easy diagnosis to miss. Good laboratory screening tests and effective treatment are available. Family practitioners should consider celiac disease in patients who present with confounding symptoms.

Algorithms↗
PubMed2004

Clostridium difficile-associated colitis.

OBJECTIVE: To review the basic microbiology, pathogenesis of disease, and diagnosis of the nosocomial pathogen Clostridium difficile and to examine therapies recommended by the Canadian Task Force on Preventive Health Care. QUALITY OF EVIDENCE MEDLINE: was searched using MeSH headings. Controlled trials for therapy were sought, but case-control studies and observational reviews were included. MAIN MESSAGE: Clostridium difficile causes approximately 20% of cases of diarrhea associated with antibiotics, including clindamycin and the second- and third-generation cephalosporins. Diarrhea is usually mild, but can be severe; extreme cases develop toxic megacolon. Diagnosis is dependent on demonstrating presence of clostridial toxin in stool specimens or of pseudomembranes through sigmoidoscopy. First-line therapy for C. difficile diarrhea is restricted to metronidazole. Second-line therapy for treatment failure is vancomycin. For relapse, a second course of metronidazole is recommended; tapering courses of vancomycin and probiotics are used for multiple recurrences. CONCLUSION: Clostridium difficile is an important nosocomial pathogen requiring prudent use of antibiotics and strict infection-control policies to prevent large health care costs.

Anti-Bacterial Agents↗
PubMed2003

Transforming growth factor-beta mediates intestinal healing and susceptibility to injury in vitro and in vivo through epithelial cells.

In vitro studies suggest that transforming growth factor (TGF)-beta has potent effects on gastrointestinal mucosal integrity, wound repair, and neoplasia. However, the multiplicity of actions of this peptide on many different cell types confounds efforts to define the role of TGF-beta within the intestinal epithelium in vivo. To delineate these effects selective blockade of intestinal epithelial TGF-beta activity was undertaken through targeted expression of a dominant-negative (DN) TGF-beta RII to intestinal epithelial cells in vitro and in vivo. Stable intestinal epithelial cell (IEC)-6 lines overexpressing TGF-beta RII-DN (nucleotides -7 to 573) were established. Transgenic mice overexpressing TGF-beta RII-DN under the regulation of a modified liver fatty acid-binding promoter (LFABP-PTS4) were constructed. In vitro healing was assessed by wounding of confluent monolayers. Colitis was induced by the addition of dextran sodium sulfate (2.5 to 7.5% w/v) to their drinking water. Overexpression of TGF-beta RII-DN in intestinal epithelial cell-6 cells resulted in a marked reduction in cell migration and TGF-beta-stimulated wound healing in vitro. TGF-beta RII-DN transgenic mice did not exhibit baseline intestinal inflammation or changes in survival, body weight, epithelial cell proliferation, aberrant crypt foci, or tumor formation. TGF-beta RII-DN mice were markedly more susceptible to dextran sodium sulfate-induced colitis and exhibited impaired recovery after colonic injury. TGF-beta is required for intestinal mucosal healing and TGF-beta modulation of the intestinal epithelium plays a central role in determining susceptibility to injury.

Animals↗
PubMed2003

Diagnosis of portal hypertensive gastropathy.

Portal hypertensive gastropathy is a relatively recently described entity that is an important cause of bleeding in portal hypertension. This article focuses on the endoscopic diagnosis of portal hypertensive gastropathy, including a review of different proposed scoring systems, and briefly examines the epidemiology, pathogenesis, and treatment of portal hypertensive gastropathy.

Journal Article↗
PubMed2003

Lymphocytic and collagenous colitis: the emerging entity of microscopic colitis. An update on pathophysiology, diagnosis and management.

Microscopic colitis (MC) encompasses the two morphologically distinct entities of collagenous colitis (CC) and lymphocytic colitis (LC). MC was first described less than 30 years ago but is presently recognized as a relatively common cause of chronic diarrhea in the adult population. Remarkably, up to 10% of adults who have a colonoscopy for the investigation of chronic diarrhea, and have endoscopically normal appearing mucosa, may have MC. Patients with MC generally present with chronic diarrhea, which can be associated with cramping and bloating. Endoscopic and radiological examinations are usually normal. Histological assessment reveals inflammation consisting predominantly of lymphocytic infiltration, and a thickened subepithelial collagen band is diagnostic of CC. Both LC and CC can be associated with autoimmune diseases such as celiac disease, diabetes, arthritis and thyroiditis, yet the mechanisms involved in the pathogenesis remain unclear. Emerging studies suggest that a stepwise approach be taken in the medical management of MC. This approach includes antidiarrheal agents and stopping of any offending agents; budesonide or bismuth subsalicylate; and cholestyramine or 5-acetylsalicylic acid agents. In resistant cases, oral corticosteroids and other immune modulatory therapy have been used.

Algorithms↗
PubMed2003

Octreotide treatment of massive hemorrhage due to cytomegalovirus colitis.

Cytomegalovirus (CMV)-associated colitis can result in abdominal pain, diarrhea, significant blood loss and perforation. The standard therapy for CMV colitis includes supportive measures and antiviral medications. Severe hemorrhage due to CMV colitis often necessitates surgical resection. We present a case of a patient who was undergoing chemotherapy for acute B-cell lymphoblastic leukemia and developed significant abdominal pain and diarrhea followed by massive hematochezia. Colonoscopy showed numerous actively bleeding deep ulcers in the cecum. A provisional diagnosis of CMV colitis was made and she was started on ganciclovir. Histological assessment confirmed the diagnosis of CMV colitis. She continued to bleed profusely per rectum over the following five days, passing up to 1 L to 1.5 L of blood per day. She required 10 units of packed red blood cells over this time period. The patient refused surgical intervention and after discussion of possible options, octreotide was instituted. Her blood loss stopped almost immediately and she required no further transfusions. She tolerated the medication well and was discharged home at a later date in stable condition. This is the first reported case of the use of octreotide in the treatment of massive hematochezia from CMV colitis.

Colitis↗
PubMed2002

Gallbladder polyps: epidemiology, natural history and management.

Polypoid lesions of the gallbladder affect approximately 5% of the adult population. Most affected individuals are asymptomatic, and their gallbladder polyps are detected during abdominal ultrasonography performed for unrelated conditions. Although the majority of gallbladder polyps are benign, most commonly cholesterol polyps, malignant transformation is a concern. The differentiation of benign from malignant lesions can be challenging. Several features, including patient age, polyp size and number, and rapid growth of polyps, are important discriminating features between benign and malignant polyps. Based on the evidence highlighted in this review, the authors recommend resection in symptomatic patients, as well as in asymptomatic individuals over 50 years of age, or those whose polyps are solitary, greater than 10 mm in diameter, or associated with gallstones or polyp growth on serial ultrasonography. Novel imaging techniques, including endoscopic ultrasonography and enhanced computed tomography, may aid in the differential diagnosis of these lesions and permit expectant management.

Cholecystectomy↗
PubMed2002

Simple construction of a subcutaneous catheter for treatment of severe subcutaneous emphysema.

Subcutaneous emphysema often presents a management dilemma. Rarely, subcutaneous emphysema has pathophysiologic consequences. More often, it is extremely uncomfortable for the patient, and is often disfiguring and alarming for patients and family. When subcutaneous emphysema is severe, physicians may feel compelled to treat it, but the currently described techniques are often invasive or ineffective. We describe the use of an easily constructed, minimally invasive, fenestrated catheter that relieves the symptoms of subcutaneous emphysema.

Catheterization↗