Biomedical subjects

P W N Keeling

Publications and source records attributed to P W N Keeling.

10 recordsLinked to original sources

PubMed2006

Cholecystokinin hyperresponsiveness in functional dyspepsia.

Functional dyspepsia (FD) is a common disorder of yet uncertain etiology. Dyspeptic symptoms are usually meal related and suggest an association to gastrointestinal (GI) sensorimotor dysfunction. Cholecystokinin (CCK) is an established brain-gut peptide that plays an important regulatory role in gastrointestinal function. It inhibits gastric motility and emptying via a capsaicin sensitive vagal pathway. The effects on emptying are via its action on the proximal stomach and pylorus. CCK is also involved in the regulation of food intake. It is released in the gut in response to a meal and acts via vagal afferents to induce satiety. Furthermore CCK has also been shown to be involved in the pathogenesis of panic disorder, anxiety and pain. Other neurotransmitters such as serotonin and noradrenaline may be implicated with CCK in the coordination of GI activity. In addition, intravenous administration of CCK has been observed to reproduce the symptoms in FD and this effect can be blocked both by atropine and loxiglumide (CCK-A antagonist). It is possible that an altered response to CCK may be responsible for the commonly observed gastric sensorimotor dysfunction, which may then be associated with the genesis of dyspeptic symptoms.

Atropine↗

PubMed2006

Role of cholecystokinin and central serotonergic receptors in functional dyspepsia.

Symptoms of functional dyspepsia are characterized by upper abdominal discomfort or pain, early satiety, postprandial fullness,bloating, nausea and vomiting. It is a chronic disorder, with symptoms more than 3 mo per year,and no evidence of organic diseases. Dysfunctional motility, altered visceral sensation, and psychosocial factors have all been identified as major pathophysiological mechanisms. It is believed that these pathophysiological mechanisms interact to produce the observed symptoms. Dyspepsia has been categorized into three subgroups based on dominant symptoms. Dysmotility-like dyspepsia describes a subgroup of patients whose symptom complex is usually related to a gastric sensorimotor dysfunction. The brain-gut peptide cholecystokinin (CCK) and serotonin (5-HT) share certain physiological effects. Both have been shown to decrease gastric emptying and affect satiety. Furthermore the CCK induced anorexia depended on serotonergic functions probably acting via central pathways. We believe that abnormalities of central serotonergic receptors functioning together with a hyper responsiveness to CCK or their interactions may be responsible for the genesis of symptoms in functional dyspepsia (FD).

Cholecystokinin↗

PubMed2006

"Best practice' for Helicobacter pylori eradication in the primary care setting.

This study determined the relative cost effectiveness of proton pump inhibitor (PPI) based triple therapy regimens for Helicobacter pylori eradication in the primary care setting. Using decision tree analysis the expected cost for each H. pylori eradication strategy was determined from the cost of each treatment option multiplied by the probability of that option occurring. Probabilities were obtained using the GMS prescribing database where all patients who received amoxycillin, clarithromycin and a PPI in the ERHA region in 2002 were followed for one year. Depending on the regimen adopted, 40.8% to 46.1% of patients did not require any further medication in the year following H. pylori eradication treatment. The strategy of rabeprazole, amoxycillin and clarithromycin was the most cost effective option with a cost of Euro466 per asymptomatic patient. Two-way sensitivity analysis indicated that the cost of rabeprazole triple therapy and the duration of rabeprazole maintenance therapy would each have to increase by 30% before this strategy ceased to be the most cost effective and hence best practice option for eradicating Helicobacter pylori in the primary care setting in Ireland.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2005

Proinflammatory cytokine and nuclear factor kappa-B expression along the inflammation-metaplasia-dysplasia-adenocarcinoma sequence in the esophagus.

BACKGROUND: The incidence of esophageal adenocarcinoma has increased significantly in the western world over the last 20 yr. Most cases arise in a background of chronic gastroesophageal reflux, and specialized intestinal metaplasia in Barrett's esophagus is frequently an antecedent phenotype or evident in association with adenocarcinoma. The molecular events that characterize the pathway from inflammation to metaplasia to dysplasia and adenocarcinoma are poorly understood. AIMS: To examine the expression of the proinflammatory cytokines IL-8 and IL-1beta along the esophagitis, metaplasia, dysplasia, and adenocarcinoma pathway, and to correlate this with histological changes and expression of the transcription factor NF-kappaB. PATIENTS AND METHODS: Fresh biopsy specimens were collected from patients with reflux esophagitis (n=15), Barrett's esophagus (n=35), Barrett's adjacent to adenocarcinoma (n=8), and esophageal adenocarcinoma (n=35). IL-8 and IL-1beta expression were measured using enzyme-linked immunosorbent assay. NF-kappaB expression was measured by electrophoretic mobility shift assay. RESULTS: Elevated expression of NF-kappaB was found in 2 (13%) out of 15 patients with reflux esophagitis, 21 (60%) out of 35 patients with Barrett's esophagus, and 28 (80%) out of 35 patients with esophageal adenocarcinoma. All 5 patients with Barrett's esophagus and high-grade dysplasia showed elevated expression of NF-kappaB. IL-8 and IL-1beta were significantly increased in esophagitis, Barrett's, and adenocarcinoma compared with squamous epithelium, and in adenocarcinoma compared with all other groups. There was a stepwise increase in the expression of IL-8, IL-1beta, and NF-kappaB from normal through Barrett's epithelium to adenocarcinoma in eight cases of esophageal adenocarcinoma. The levels of both IL-8 and IL-1beta in adenocarcinoma patients correlated with stage of disease. Patients with adenocarcinoma who were NF-kappaB positive had significantly higher levels of both IL-8 (p=0.04) and IL-1beta (p=0.03) compared to adenocarcinoma patients who were NF-kappaB negative. CONCLUSIONS: The proinflammatory cytokines IL-8 and IL-1beta are elevated in esophagitis and Barrett's epithelium, and markedly elevated in adenocarcinoma. NF-kappaB activation is infrequent in esophagitis, but is increased in Barrett's epithelium and adenocarcinoma. The association of NF-kappaB activation with cytokine upregulation was only evident in patients with adenocarcinoma. These patterns may play an important role in Barrett's inflammation and tumourigenesis, and inhibition of the NF-kappaB/proinflammatory cytokine pathway may be an important target for future chemoprevention strategies.

Adenocarcinoma↗

PubMed2004

Factors influencing the development of Barrett's epithelium in the esophageal remnant postesophagectomy.

BACKGROUND: Barrett's esophagus results from chronic reflux of both acid and bile. Reflux of gastric and duodenal contents is facilitated through the denervated stomach following esophagectomy, but the development of Barrett's changes in this model and the relationship to gastric and esophageal physiology is poorly understood. AIMS: To document the development of new Barrett's changes, i.e., columnar metaplasia or specialized intestinal metaplasia (SIM) above the anastomosis, and relate this to the recovery of gastric acid production, acid and bile reflux, manometry, and symptoms. PATIENTS AND METHODS: Forty-eight patients at a median follow-up of 26 months (range = 12-67) postesophagectomy underwent endoscopy with biopsies taken 1-2 cm above the anastomosis. The indication for esophagectomy had been adenocarcinoma (n = 27), high-grade dysplasia (n = 2), and squamous cell cancer (n = 19). Physiology studies were performed in 27 patients and included manometry (n = 25), intraluminal gastric pH (n = 24), as well as simultaneous 24-hour esophageal pH (n = 27) and bile monitoring (n = 20). RESULTS: Duodenogastric reflux increased over time, with differences between patients greater than and less than 3 years postesophagectomy for acid (p = 0.04) and bile (p = 0.02). Twenty-four patients (50%) developed columnar metaplasia and of these 13 had SIM. The prevalence of columnar metaplasia did not relate to the magnitude of acid or bile reflux, to preoperative neoadjuvant therapies, or to the original tumor histology. The duration of reflux was most significant, with increasing prevalence over time, with SIM in 13 patients at a median of 61 months postesophagectomy compared with 20 months in the 35 patients who were SIM-negative (p < 0.006). Supine reflux correlated with symptoms. CONCLUSIONS: The development of Barrett's epithelium is frequent after esophagectomy, is time-related, reflecting chronic acid and bile exposure, and is not specific for adenocarcinoma or the presence of previous Barrett's epithelium. This model may represent a useful in vivo model of the pathogenesis of Barrett's metaplasia and tumorigenesis.

Adenocarcinoma↗

PubMed2003

Transvenous liver biopsy via the femoral vein.

AIM: To study the safety, effectiveness and diagnostic value of transvenous forceps biopsy of the liver in 54 patients with coagulopathy, gross ascites or morbid obesity and suspected liver disease in whom percutaneous liver biopsy was contraindicated. MATERIAL AND METHODS: Forceps biopsy of the liver via the femoral vein was attempted in 54 adult patients with advanced liver disease of unknown aetiology who had coagulation disorders (41 cases), gross ascites (11 cases) or morbid obesity (two cases). In each patient two to six biopsies (average four) were taken using a radial jaw forceps inserted via the right or left femoral vein. RESULTS: The procedure was successful in 53 cases. Hepatic vein catheterization failed in one patient. Adequate liver tissue for diagnosis was obtained in 84% of cases. One patient developed delayed haemorrhage at 12 h from a capsular leak that was undetected during the biopsy procedure. This patient required blood transfusions and laparotomy to control bleeding. There were no deaths in the 53 patients studied. Transient minor chest and shoulder pain was encountered during sheath insertion into a hepatic vein in 23 patients. Three patients developed a femoral vein haematoma, which resolved with conservative treatment. CONCLUSION: Transvenous liver biopsy via the femoral vein is another safe, effective, simple alternative technique of biopsy when the percutaneous route is contraindicated.

Adult↗

PubMed2003

Impaired visceral sensitivity to acid reflux in patients with Barrett's esophagus. The role of esophageal motility*.

Patients with Barrett's esophagus have been reported to have impaired visceral sensitivity to acid perfusion and distension compared with non-Barrett's refluxers, but the mechanism is poorly understood. Esophageal motility and clearance mechanisms may be important, and this study explored the relationship of motility with symptoms. Seventy-four patients with Barrett's esophagus were compared with 216 patients with gastro-esophageal reflux disease (GERD) with abnormal acid reflux scores, and 50 symptomatic patients who had normal acid exposure. All patients had esophageal manometry and 24-h pH monitoring. Thirty-six Barrett's patients also had 24-h bile reflux monitoring. Symptoms were assessed by Symptom Index (SI) during 24-h pH monitoring. Barrett's patients with normal motility had a significantly lower SI than GERD patients for similar acid exposure (P < 0.001). Barrett's patients with abnormal motility had higher acid exposure than those with normal motility (P < 0.05), but the SI values for this group was not significantly different from the GERD patients. SI and Bile reflux in Barrett's esophagus was not significantly different in patients with normal or abnormal motility. Barrett's patients had less sensitivity than GERD patients for similar acid exposure. Normal motility in Barrett's esophagus is associated with the poorest sensitivity and the presence of increased acid exposure is required in order to achieve sensitivity levels comparable with GERD patients.

Adolescent↗

PubMed2003

A prospective study of circulating mutant KRAS2 in the serum of patients with colorectal neoplasia: strong prognostic indicator in postoperative follow up.

BACKGROUND AND AIMS: Mutant tumour derived DNA has been detected in the sera of colorectal cancer patients. We investigated if mutant serum KRAS2 was detectable preoperatively in a large group of patients with colorectal neoplasia. A prospective study of 94 patients who underwent putative curative resection for colorectal carcinoma (CRC) was performed to ascertain if serum mutant KRAS2 could be used postoperatively as a disease marker. METHODS: Preoperative sera from 78 patients were analysed (group A). Sera from 94 patients were obtained three monthly for up to three years during the postoperative period (group B). Codon 12 and 13 KRAS2 mutations were analysed in matched tumour and serum samples. RESULTS: In the preoperative group (group A), KRAS2 mutation was found in 41/78 (53%) tumours and in 32/78 (41%) preoperative sera. Of 41 tumour KRAS2 mutation positive cases, 31/41 (76%) had an identical serum mutation detectable. In group B, the postoperative follow up group, 60/94 cases were primary tumour KRAS2 mutation positive. Of these 60, 16/60 (27%) became persistently serum mutant KRAS2 positive postoperatively. Ten of 16 (63%) of these developed a recurrence compared with only 1/44 (2%) patients who remained serum mutant negative (odds ratio 71.7 (95% confidence interval 7.7-663.9; p=0.0000). None of 34 tumour mutation negative cases became serum mutant KRAS2 positive postoperatively, despite recurrence in 9/34 patients. The relative hazard of disease recurrence in postoperative serum mutant KRAS2 positive patients was 6.37 (2.26-18.0; p=0.000). CONCLUSIONS: Serum mutant KRAS2 can be detected preoperatively in all stages of colorectal neoplasia. Postoperatively, serum mutant KRAS2 is a strong predictor of disease recurrence, stronger even than Dukes' stage of disease, and thus shows potential for use in clinical practice as a marker of preclinical disease recurrence.

Aged↗

PubMed2002

Altered hypothalamic cholinergic responses in patients with nonulcer dyspepsia: a study of pyridostigmine-stimulated growth hormone release.

OBJECTIVE: Acetylcholine plays a central and peripheral role in regulating gastric motility. In the hypothalamus, it is a key neuroendocrine modulator; acting through somatostatin, it brings about the release of growth hormone (GH). We measured hypothalamic cholinergic receptor sensitivity in patients with nonulcer dyspepsia (NUD) by examining GH release in response to cholinergic challenge. METHODS: Forty patients with NUD and 40 healthy comparison subjects were administered pyridostigmine (the acetylcholinesterase inhibitor, 120 mg), and GH release over a 3-h period was monitored. RESULTS: Calculating response as the maximum GH relative to baseline (delta GH), the mean +/- SEM response in the patients was 11.9 +/- 1.9 U/L and in the healthy subjects 6.7 +/- 0.7 mU/L (t = 2.1, df = 78, p = 0.03). Helicobacter pylori status had no appreciable impact on GH response with H. pylori-positive patients having a mean response of 10.5 +/- 2.1 mU/L and negative patients a mean response of 13.2 +/- 3.4 mU/L. Overall, patients with NUD release more GH in response to pyridostigmine challenge than healthy subjects. CONCLUSIONS: Patients with NUD may have a pathophysiological disturbance involving central cholinergic systems.

Adult↗

PubMed2002

Pituitary-adrenal response to naloxone in non-ulcer dyspepsia: preliminary evidence for a reduction in central opioid tone.

BACKGROUND: Non-ulcer dyspepsia (NUD) is one of the core functional bowel disorders. There has been recent emphasis on possible abnormal brain-gut interactions as being central to its pathophysiology. In this preliminary study, we examined central opioid tone in Helicobacter pylori-negative NUD patients using naloxone, an opioid antagonist, which stimulates pituitary-adrenal activity. The opioid system is known to govern nociceptive processing and to play a role in gut motor activity. SUBJECTS: Eight subjects with NUD and 8 age- and sex-matched healthy subjects were examined. METHODS: Naloxone, 0.125 mg/kg, was administered at time 0. Adrenocorticotropin (ACTH) and cortisol responses were measured over a 120-min period. Maximum pituitary-adrenal responses in the 2 groups were compared. RESULTS: The ACTH response was significantly attenuated in the NUD group (p < 0.05). The cortisol response did not differ between the 2 groups (p = 0.7). CONCLUSIONS: Central opioid tone may be reduced in subjects with NUD. Our preliminary findings suggest that altered opioidergic activity may contribute to NUD pathophysiology, influencing the symptom profile through altered gut motor activity or possibly by influencing visceral sensitivity.

Adrenocorticotropic Hormone↗