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Biomedical subjects

Eldon A Shaffer

Publications and source records attributed to Eldon A Shaffer.

12 recordsLinked to original sources
PubMed2006

Gallstone disease: Epidemiology of gallbladder stone disease.

Gallstone disease is common: >700,000 cholecystectomies and costs of approximately 6.5 billion dollars annually in the U.S. The burden of disease is epidemic in American Indians (60-70%); a corresponding decrease occurs in Hispanics of mixed Indian origin. Ten to fifteen per cent of white adults in developed countries harbour gallstones. Frequency is further reduced in Black Americans, East Asia and sub-Saharan Africa. In developed countries, cholesterol gallstones predominate; 15% are black pigment. East Asians develop brown pigment stones in bile ducts, associated with biliary infection or parasites, or in intrahepatic ducts (hepatolithiasis). Certain risk factors for gallstones are immutable: female gender, increasing age and ethnicity/family (genetic traits). Others are modifiable: obesity, the metabolic syndrome, rapid weight loss, certain diseases (cirrhosis, Crohn's disease) and gallbladder stasis (from spinal cord injury or drugs like somatostatin). The only established dietary risk is a high caloric intake. Protective factors include diets containing fibre, vegetable protein, nuts, calcium, vitamin C, coffee and alcohol, plus physical activity.

Adult↗
PubMed2006

Eosinophilic esophagitis: an overlooked entity in chronic dysphagia.

BACKGROUND: A 40-year-old white male with atopy presented to our department in March 2004 with a history of chronic heartburn and solid-food dysphagia since 1994. The patient was taking on-demand salbutamol for asthma and ranitidine for mild heartburn, occurring less than once per week. Eight years previously, he had undergone esophageal dilatation for a Schatzki's ring. INVESTIGATIONS: Physical examination, laboratory investigations, video esophagram, upper endoscopy with mid-esophageal biopsies, and skin testing for a number of food and environmental allergens. Diagnosis Eosinophilic esophagitis. MANAGEMENT: Topical steroids with a fluticasone 220 microg multiple-dose inhaler, four puffs swallowed twice a day for 6 weeks.

Adult↗
PubMed2006

Bariatric surgery: a promising solution for nonalcoholic steatohepatitis in the very obese.

The management of nonalcoholic fatty liver has been limited by a paucity of well-conducted studies that are of sufficient duration and quality to determine the outcome, which is best defined by liver biopsy. The mainstays, diet and physical activity plus behavioral modifications, are not always successful, particularly in the very obese. Although it is intuitive to expect that weight loss should diminish steatosis, only limited evidence exists that liver enzymes improve with reduction in body weight. The available pharmacologic therapy has focused on the two limbs of the pathogenetic basis for nonalcoholic steatohepatitis (NASH), insulin resistance and oxidative stress, but with quite limited success. Neither behavioral, nor dietary, nor drug therapy has been particularly effective either in obesity or NASH. In the severely obese, the fatty liver and its stages often have progressed to NASH or cirrhosis even before contemplating therapy. In the severely obese, the best therapeutic modality is bariatric surgery, which is safe and has been successful in producing a 61% weight loss overall. The result is improvement in diabetes mellitus, the metabolic syndrome, and presumably its sequelae. Early reports (and procedures) were attended with dramatic weight loss but markedly aggravated the inflammatory liver disease. In recent trials with more modest weight loss and less malnutrition, bariatric surgery reduced the fat, inflammation, and even the fibrosis in well-documented NASH. These promising procedures will undoubtedly increase and constitute the major therapeutic modality for those who are severely obese.

Bariatric Surgery↗
PubMed2005

Epidemiology and risk factors for gallstone disease: has the paradigm changed in the 21st century?

Gallstone disease is common and costly, creating over 700,000 cholecystectomies annually. Its complications consume approximately $6.5 billion in the United States. Surveys using noninvasive ultrasonography have identified its true prevalence and the associated risk factors. In developed countries, at least 10% of white adults harbor cholesterol gallstones; women have twice the risk, and age further increases the prevalence in both sexes. Gallstones reach epidemic proportions in the North and South American Indian populations, accompanied by an increased risk for gallbladder cancer. In contrast, the rate in sub-Saharan Africa and Asia is quite low. Obesity, a major risk factor, likely relates to insulin resistance (the metabolic syndrome). Evolution and circumstance in American Indians may have ironically selected those with "thrifty" genes that conserve energy. Our abundant access to food places us at the increased risk of obesity and cholelithiasis. The general rise in obesity in many countries raises the specter of heightened disease, best identified by epidemiologic studies.

Cholecystolithiasis↗
PubMed2004

Effect of time of administration on cholesterol-lowering by psyllium: a randomized cross-over study in normocholesterolemic or slightly hypercholesterolemic subjects.

BACKGROUND: Reports of the use of psyllium, largely in hypercholesterolemic men, have suggested that it lowers serum cholesterol as a result of the binding of bile acids in the intestinal lumen. Widespread advertisements have claimed an association between the use of soluble fibre from psyllium seed husk and a reduced risk of coronary heart disease. Given the purported mechanism of cholesterol-lowering by psyllium, we hypothesized that there would be a greater effect when psyllium is taken with breakfast than when taken at bedtime. Secondarily, we expected to confirm a cholesterol-lowering effect of psyllium in subjects with "average" cholesterol levels. METHODS: Sixteen men and 47 women ranging in age from 18 to 77 years [mean 53 +/- 13] with LDL cholesterol levels that were normal or slightly elevated but acceptable for subjects at low risk of coronary artery disease were recruited from general gastroenterology and low risk lipid clinics. Following a one month dietary stabilization period, they received an average daily dose of 12.7 g of psyllium hydrophilic mucilloid, in randomized order, for 8 weeks in the morning and 8 weeks in the evening. Change from baseline was determined for serum total cholesterol, LDL, HDL and triglycerides. RESULTS: Total cholesterol for the "AM first" group at baseline, 8 and 16 weeks was 5.76, 5.77 and 5.80 mmol/L and for the "PM first" group the corresponding values were 5.47, 5.61 and 5.57 mmol/L. No effect on any lipid parameter was demonstrated for the group as a whole or in any sub-group analysis. CONCLUSION: The timing of psyllium administration had no effect on cholesterol-lowering and, in fact, no cholesterol-lowering was observed. Conclusions regarding the effectiveness of psyllium for the prevention of heart disease in the population at large may be premature.

Clinical Trial↗
PubMed2003

Effects of bioactive agents on biliary motor function.

Our understanding of biliary motility under normal and pathophysiologic conditions is still incomplete, but there have been recent advances. Of particular interest are the mechanisms involved in gallbladder filling and emptying, with a focus on understanding the processes underlying impaired gallbladder emptying leading to gallbladder dyskinesia and the formation of gallstones or cholecystitis. The sphincter of Oddi (SO) is a complex neuromuscular structure. Recent studies have attempted to unravel the specific neural or hormonal mechanisms operating under normal physiologic conditions and those that may lead to SO dysfunction. Furthermore, new research fronts are emerging, including the role of leptin in obese patients with impaired biliary motility and the action of electroacupuncture for possible treatment of SO dysfunction. This review illustrates the broad front of current research regarding the effects of bioactive agents on biliary motility, including enteric hormones, nitric oxide, opioids, inflammatory mediators, leptin, protease inhibitors, neurotransmitters, and electroacupuncture.

Animals↗
PubMed2003

Changes in gallbladder motility and gallstone formation following laparoscopic gastric banding for morbid obestity.

UNLABELLED: Morbid obesity is associated with cholesterol gallstone formation, a risk compounded by rapid weight loss. Laparoscopic gastric banding allows for a measured rate of weight loss, but the subsequent risk for developing gallstones is unknown. METHOD: Twenty-six normal-weight volunteers (body mass index [BMI] less than 30) were compared with 14 morbidly obese patients (BMI greater than 40). Gallbladder volumes were measured ultrasonographically, after fasting and following stimulation with intravenous cholecystokinin-octapeptide (CCK-8) RESULTS: Preoperatively, fasting gallbladder volume and residual volume after CCK stimulation were both two times greater in the obese group (P<0.02 versus controls). Per cent gallbladder emptying was not different. Gallbladder refilling was four times higher in the obese patients (P<0.01). By six weeks postoperatively, the obese patients lost 1.4+/-0.1% body weight per week. Gallbladder emptying decreased 18.4% (80.3+/-3.9% to 65.5+/-6.9%; P<0.05); residual volume rose one-third (not significant), and refilling fell 60.5% (0.43+/-0.09 to 0.26+/-0.04 mL/min; P=0.07). Three patients with weight losses of greater than 1.7% per week developed gallstones; gallbladder emptying fell outside the 95 percentile. By six months, weight loss slowed to 0.5+/-0.1% per week; gallbladder motility improved modestly. No further stones developed. CONCLUSION: Rapid weight loss following laparoscopic gastric banding impairs gallbladder emptying and when pronounced, gallstones form by six weeks postoperatively. The accompanying reduction in gallbladder emptying, increased gallbladder residual volume and decreased refilling promote gallbladder stasis and hence stone formation.

Adult↗
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

Cholestasis: the ABCs of cellular mechanisms for impaired bile secretion--transporters and genes.

The transport of bile salts, organic anions and cations, bilirubin and other substances from the portal blood into the biliary system is accomplished through the action of an array of transporter proteins in the hepatocyte. Transporters on the basolateral membrane, which faces the space of Disse, are responsible for the uptake of bile salts and organic anions. Once translocated through the hepatocyte to the canalicular membrane, other ATP pumps provide the energy to export bile salts, phospholipids and organic ions into the bile. Canalicular transport is rate limiting. Defects in specific canalicular transporters are responsible for many of the intrahepatic cholestatic syndromes that occur in children and adults. Moreover, cholestasis provokes changes in several transport mechanisms, many of which appear to be compensatory and serve to protect the liver from the toxic effects of accumulated materials. The identification and characterization of the major transporters responsible for bile formation have yielded a more precise classification of the cholestatic syndromes of infancy and childhood, and are unlocking the molecular mechanism of acquired cholestasis in adults. This review identifies the basic physiology of bile production and the actions of the key transporters, indicates the clinical relevance and possible treatments of transport disorders, and provides an illustrative case.

ATP-Binding Cassette Transporters↗