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Biomedical subjects

A J Cameron

Publications and source records attributed to A J Cameron.

At least 37 records · Page 2Linked to original sources
PubMed1998

Management of Barrett's esophagus.

In Barrett's esophagus, the squamous lining of the lower esophagus is replaced by columnar epithelium. Barrett's esophagus is associated with gastroesophageal reflux and an increased risk of the development of esophageal cancer. Endoscopy shows red columnar epithelium in the lower esophagus. Biopsy is needed to confirm intestinal metaplasia. Some cases progress from dysplasia to invasive adenocarcinoma. Medical or surgical antireflux treatment controls symptoms and esophagitis, but Barrett's esophagus remains. Patients are usually followed up by endoscopy for detection of dysplasia or early cancer. For patients with low-grade dysplasia, follow-up is adequate; however, for those with high-grade dysplasia, esophagectomy or experimental endoscopic mucosal ablation is advised.

Adenocarcinoma↗
PubMed1997

Epidemiology of columnar-lined esophagus and adenocarcinoma.

Barrett's esophagus is found in about 1% of the older population and in 3% to 5% of persons with gastroesophageal reflux. It is acquired more commonly by men and the prevalence increases with age. Most cases in the population remain undiagnosed. The incidence of adenocarcinoma of the esophagus and esophagogastric junction is increasing, both being related to Barrett's esophagus. Small areas of intestinal metaplasia are common but of uncertain significance.

Adenocarcinoma↗
PubMed1997

Familial aggregation of gastroesophageal reflux in patients with Barrett's esophagus and esophageal adenocarcinoma.

BACKGROUND & AIMS: Barrett's esophagus and adenocarcinoma are complications of gastroesophageal reflux disease. The aim of this study was to look for evidence of a familial predisposition to reflux. METHODS: Index patients with adenocarcinoma (n = 27), Barrett's esophagus (n = 40), and reflux esophagitis (n = 55) were recruited from tertiary care and community populations. Parents and siblings of patients (n = 243) and their spouses' relatives (n = 230) completed reflux symptom questionnaires (response rate, 86%). RESULTS: Reflux symptoms were significantly more prevalent among parents and siblings of patients with adenocarcinoma (43% vs. 23%) and Barrett's esophagus (46% vs. 27%) than spouse control relatives. No significant difference was found for the reflux esophagitis group (33% vs. 29%). Reflux was more prevalent in siblings than spouses of patients with Barrett's esophagus (41% vs. 12%) and adenocarcinoma (40% vs. 6%), a difference that was not found with reflux esophagitis (24% vs. 32%). Reflux was associated with obesity, 41% vs. 28% in the nonobese; smoking, 45% vs. 31% in nonsmokers; and men, 39% vs. 27% in women. CONCLUSIONS: There may be a genetic predisposition to the development of reflux in families of patients with Barrett's esophagus and esophageal adenocarcinoma. For uncomplicated reflux esophagitis, environmental factors appear more important.

Adenocarcinoma↗
PubMed1997

Barrett's esophagus, high-grade dysplasia, and early adenocarcinoma: a pathological study.

OBJECTIVES: In Barrett's esophagus, early adenocarcinomas are often missed on endoscopic biopsy. We therefore examined the distribution and extent of dysplasia and carcinoma in the resected esophagus for comparison with the preoperative biopsy findings. METHODS: Patients whose endoscopy showed Barrett's esophagus but no visible cancer had four-quadrant esophageal biopsies taken every 2 cm. After resection for high-grade dysplasia or early adenocarcinoma, the esophagus was mapped histologically. RESULTS: Nineteen patients had surgery for high-grade dysplasia; two of them (10.5%) had adenocarcinoma in the resected esophagus. Eleven patients had resection after a biopsy diagnosis of adenocarcinoma or suspicion of adenocarcinoma. Esophagectomy mapping confirmed carcinoma in only five of them. Median surface areas were: total Barrett's esophagus 32 sq cm, low-grade dysplasia 13 sq cm, high-grade dysplasia 1.3 sq cm, adenocarcinoma (seven cases) 1.1 sq cm. CONCLUSIONS: Areas of high-grade dysplasia and microscopic carcinoma in Barrett's esophagus are often small. Biopsy differentiation between these lesions is difficult. A systematic endoscopic biopsy protocol will reduce the chance of missing early malignancy in Barrett's esophagus.

Adenocarcinoma↗
PubMed1997

School-based smoking control: a research agenda.

Within the context of a framework for cancer control, this article reviews evidence and suggests research directions for 3 types of school-based smoking interventions: elementary school prevention, secondary school interventions and interventions linking community and school. Directions for smoking research in elementary schools include improving adoption through the provision of effectiveness criteria, tailoring interventions to schools and training. Monitoring at micro and macro levels may help planning and implementation, but clearer evidence is required of its feasibility. Fundamental research should explore new options to understand why youth do not start smoking. Smoking intervention research at the secondary school level is less well established, with only 1 effectiveness trial reported. We recommend testing models that involve youth in developing their own solutions and examining the interaction of various control measures. Sustainability issues have led researchers to embed school-based smoking interventions in community-wide activities. Intervention research of this sort still needs to determine how to apply approaches (e.g., comprehensive school health) and what the appropriate roles are (such as technical assistance) for community agencies. All research using these school-community approaches needs to include process measures to explain potential failures to obtain significant differences between components. In addition, we call for research on the training of educators and health personnel, to increase the priority given to smoking prevention and improve the implementation of existing programs. Research on policy initiatives that lead to effective training needs to be explored. Finally, we argue that application of the principles incorporated into the cancer control framework (e.g., through participatory research methods) strengthens the research process and results.

Adolescent↗
PubMed1997

Critique of the National Cancer Institute of Canada's framework for cancer control.

This paper offers a critique of the National Cancer Institute of Canada's (NCIC) framework for cancer control. The critique has been prepared by researchers who used the framework to review the literature in 5 substantive areas. These reviews, published in the current and previous issues of CPC, were designed to begin to outline a research agenda for the Sociobehavioural Cancer Research Network. In this paper, the authors reflect on the strengths and limitations of the framework. Perceived strengths are that the framework (a) facilitates systematic thinking about research options and priorities, (b) helps foster clear communication, (c) links science and practice, (d) may assist grant review panels to place proposed studies in context and (e) emphasizes important values. Perceived concerns include the following: (a) potential users are not familiar with the framework, (b) lack of clarity of definitions and classification criteria, (c) the utility of the framework is not immediately self-evident to potential users, (d) the framework lacks emphasis on environmental and policy interventions and (e) it is not clear how the values espoused are to be integrated with other dimensions of the framework. The concerns were seen as remediable. In short, the framework was seen to be valuable in its current form; refinement may enhance its value.

Canada↗
PubMed1995

Peptidergic and nitrinergic denervation in congenital esophageal stenosis.

Congenital esophageal stenosis (CES) is a rare disorder with narrowed esophageal lumen that presents as dysphagia from childhood and that is often associated with tracheobronchial remnants or webs. The pathogenesis of CES is unknown. The aim of this study was to examine the histological and immunohistochemical features of CES. Esophagi from 2 young adults with CES and 3 controls with no motility disorders underwent routine H&E staining, trichrome staining for collagen, and detailed immunocytochemical studies for general neuronal markers (protein gene product 9.5, neuron-specific enolase, and S-100) and neurotransmitters (vasoactive intestinal polypeptide, substance P, and galanin) and nitric oxide synthase by beta-nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase and a specific NO synthase antibody. Quantitative experiments compared the numbers of myenteric neurons and amounts of fibers at the circular muscle. CES esophagi showed infiltration of neutrophils in the myenteric plane, without any increase in collagen. NADPH-diaphorase histochemistry showed a significant reduction of myenteric nitrinergic neurons (7 +/- 3.4 vs. 2.7 +/- 1.8 neurons per high-power field) and fibers at the circular muscle. Other peptidergic neurons studied were not significantly reduced in CES. The specific total lack of NO inhibitory innervation may be an important mechanism in the pathogenesis of stenosis and aperistalsis of the esophagus in this disorder.

Adult↗
PubMed1995

Adenocarcinoma of the esophagogastric junction and Barrett's esophagus.

BACKGROUND & AIMS: Barrett's esophagus is associated with adenocarcinoma of the esophagus. The aim of this study was to find the prevalence of Barrett's esophagus in patients with adenocarcinoma of the esophagogastric junction. METHODS: Consecutive, freshly resected surgical esophagogastrectomy specimens were examined, and multiple histological sections were made around the tumor periphery. Barrett's esophagus was defined as specialized columnar epithelium above the esophagogastric junction. Tumors centered < or = 2 cm from the junction were defined as junction cancers. RESULTS: Barrett's esophagus was found in 9 of 9 (100%) esophageal adenocarcinomas compared with 0 of 8 (0%) squamous carcinoma controls (P < 0.001). Ten of 24 (42%) junction adenocarcinomas had a Barrett's esophagus. A Barrett's esophagus was found in 8 of 12 (67%) junction cancers < or = 6 cm in length but only 2 of 12 (17%) larger tumors (P < 0.05). Barrett's esophagus was significantly associated with junction tumors < 6 cm compared with squamous carcinoma controls (P < 0.02). In 5 specimens with junction cancer, the length of Barrett's esophagus was < 3 cm, and in 5 specimens it was > or = 3 cm. Specialized epithelium was often found below the esophagogastric junction in controls. CONCLUSIONS: Adenocarcinomas of the esophagogastric junction are associated with short and long segments of Barrett's esophagus. Larger cancers probably overgrow and conceal the underlying specialized columnar epithelium from which they arise.

Adenocarcinoma↗
PubMed1995

Isolation and cloning of a protein-serine/threonine phosphatase from an archaeon.

A divalent metal ion-stimulated protein-serine/threonine phosphatase, PP1-arch, was purified approximately 1,000-fold from the extreme acidothermophilic archaeon Sulfolobus solfataricus (ATCC 35091). Purified preparations contained 40 to 70% of total protein as PP1-arch, as determined by assay-ing sodium dodecyl sulfate-polyacrylamide gels for protein phosphatase activity. The first 25 amino acids of the protein's sequence were identified, as well as an internal sequence spanning some 20 amino acids. Using this information, we cloned the gene for PP1-arch via the application of PCR and conventional cloning techniques. The gene for PP1-arch predicted a protein of 293 amino acids that bore striking resemblance to the members of the major family of protein-serine/threonine phosphatases from members of the domain Eucarya, the PP1/2A/2B superfamily. The core of the protein, spanning residues 4 to 275, possessed 29 to 31% identity with these eucaryal protein phosphatases. Of the 42 residues found to be absolutely conserved among the known eucaryal members of the PP1/2A/2B superfamily, 33 were present in PP1-arch. If highly conservative substitutions are included, this total reached 37. The great degree of sequence conservation between molecules from two distinct phylogenetic domains implies that the members of this enzyme superfamily had evolved as specialized, dedicated protein phosphatases prior to the divergence of members of the Archaea and Eucarya from one another.

Amino Acid Sequence↗
PubMed1995

Endoscopic esophageal manometry.

OBJECTIVE: We performed through-the-scope-manometry of the esophagus on 12 patients referred for esophageal symptoms. METHODS: A 3-lumen polyvinyl tube was passed through the biopsy channel of a standard video-endoscope. All patients underwent esophagogastroduodenoscopy with through-the-scope-manometry as well as a conventional laboratory-based manometric study; the sequence of the procedures was randomized. RESULTS: Mean lower esophageal sphincter pressure was 18 +/- 11 mm of mercury by both methods. In the lower esophagus, mean wave amplitude was 60 +/- 25 mm of mercury by through-the-scope manometry and 82 +/- 28 by laboratory testing. In the upper esophagus, mean wave amplitude was 50 +/- 26 mm of mercury by through-the-scope manometry and 63 +/- 20 by laboratory testing. Wave duration tended to be lower by through-the-scope manometry than by laboratory testing in the lower and upper esophagus. In nine patients with normal esophageal motility, 54% of swallows resulted in a peristaltic wave by the endoscopic study versus 100% for the laboratory test. CONCLUSION: Through-the-scope-manometry was able to accurately measure lower esophageal sphincter pressure compared with laboratory-based manometry. Peristaltic wave amplitude by through-the-scope manometry was reduced compared with laboratory-based manometry, most likely because of the use of dry swallows. Through-the-scope-manometry has promise as a screening test for esophageal motility disorders.

Endoscopy, Digestive System↗
PubMed1995

Primary leiomyosarcoma of the liver mimicking liver abscess.

Primary hepatic leiomyosarcoma is a rare tumor, with fewer than 60 previously reported cases. The usual clinical presentation is painful hepatomegaly or a painful epigastric mass. We present the case of a 64-yr-old white man who presented with fevers, drenching night sweats, fatigue, leukocytosis, an elevated erythrocyte sedimentation rate, and an indistinct mass in the right lobe of his liver on CT scan. Although the clinical presentation was suggestive of hepatic abscess, a percutaneous biopsy was consistent with a smooth muscle tumor. Successful right hepatic lobectomy resulted in resolution of all the associated symptoms and signs. A review of the world literature produced 44 papers reporting a total of 54 cases. The male:female ratio was 25:26; mean age was 53.6 yr. The tumor tended to occur at an earlier age in women, with a group mean age of 49.0 yr compared with 58.4 for men. It was more common in the right lobe. Metastatic disease was present in 40.9% of patients. The outcomes for various therapeutic approaches were compared. Patients treated with comfort measures alone had a mean survival or follow-up of 0.87 yr. The best outcome seemed to be in those patients treated with a combination of surgery and chemotherapy, with a mean survival or follow-up of 3.3 yr.

Adenoma↗
PubMed1994

Gastroesophageal reflux and chronic cough: which comes first?

We evaluated the relationship between gastroesophageal (GE) reflux and chronic cough using prolonged pH monitoring and the standard acid reflux study in a retrospective case review. Ten patients were referred to our clinical esophageal laboratory for prolonged pH monitoring to determine whether GE reflux was the cause of chronic cough. In addition, we report one patient referred for a standard acid reflux test as a clear example of spontaneous cough inducing GE reflux. Of the 10 patients having prolonged pH monitoring, 182 of 221 (80.9 +/- 4.6%) of cough episodes had no correlation with GE reflux (p = 0.0001). Of those cough episodes that appeared to be related to GE reflux, 27 of 39 (69.2 +/- 11.7%) occurred before GE reflux and 12/39 (30.8 +/- 10.3%) occurred after GE reflux (p = 0.06). In the single patient GE reflux after spontaneous cough occurred five of seven times during a standard acid reflux test. In our series, cough and reflux were not related in the majority of episodes. Where there was a relationship, it appeared that the cough preceded GE reflux twice as often as reflux preceded cough. We conclude that GE reflux does not appear to be a frequent cause of chronic cough.

Aged↗
PubMed1993

Increasing incidence of adenocarcinoma of the esophagus and esophagogastric junction.

BACKGROUND: The aim of this study was to determine whether the incidence of adenocarcinoma of the esophagus and esophagogastric junction in a well-defined population was higher than previously recognized. METHODS: Clinical records and original histological slides from patients residing in Olmsted County, Minnesota, were reviewed and compared with a previous study in the same population. RESULTS: The incidence of esophageal adenocarcinoma rose from 0.13 for 1935-1971 to 0.74 for 1974-1989, and the incidence of adenocarcinoma of the esophagogastric junction rose from 0.25 to 1.34 per 100,000 person-years. Histological review of preserved surgical specimens showed associated intestinal metaplasia (Barrett's esophagus) in 2 of 2 esophageal and in 5 of 9 esophagogastric adenocarcinomas. CONCLUSIONS: The incidence of adenocarcinoma in each location increased five to sixfold compared with the earlier study. This increase could not be explained by improved diagnostic methods or classification changes. The association with Barrett's esophagus and the parallel increased incidence of cancer in each location is evidence that adenocarcinoma of the esophagus and of the esophagogastric junction are related disorders.

Adenocarcinoma↗
PubMed1993

Achalasia: prospective evaluation of relationship between lower esophageal sphincter pressure, esophageal transit, and esophageal diameter and symptoms in response to pneumatic dilation.

The aims of this study were to investigate a group of patients with achalasia prospectively to determine (1) the relationship between changes in symptoms and esophageal motor function in response to pneumatic dilation and (2) the effects of the balloon size as well as the frequency and duration of inflation on the outcome of treatment. Fourteen patients with achalasia who were symptomatic for a median duration of 27 months participated in the study. The patients were randomized to one combination of the following pneumatic dilation conditions: a 30- or 35-mm balloon dilator, one or two balloon inflations, and 20, 40, or 60 seconds per balloon inflation. A comprehensive assessment of their symptoms and esophageal motility, transit, and diameter were performed before and 3 months after pneumatic dilation. Pneumatic dilation provided significant relief of dysphagia (P < 0.01), but other symptoms (heartburn, regurgitation, and chest pain) remained unchanged. Pneumatic dilation also caused a significant decrease in lower esophageal sphincter pressure and esophageal diameter and improved esophageal emptying of a solid bolus. Nevertheless, no significant association was detected between changes in the symptom score for dysphagia and changes in objective response measures as a result of pneumatic dilation. Changes in the symptom score for dysphagia or objective responses were similar regardless of the size of the dilator used or the frequency and duration of the balloon inflations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗