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R W McCallum

Publications and source records attributed to R W McCallum.

At least 19 recordsLinked to original sources
PubMed2006

Symptom responses, long-term outcomes and adverse events beyond 3 years of high-frequency gastric electrical stimulation for gastroparesis.

The aims were to determine symptom responses and long-term outcomes in gastroparetic patients receiving gastric electrical stimulation (GES) therapy beyond 3 years by presenting per protocol analysis and intention-to-treat (ITT) analysis. Data collected at baseline, 1 year and beyond 3 years in 55 patients included total symptom scores (TSS), nutritional status, weight, hospitalizations, the use of prokinetic and/or antiemetic medications, HbA1c in diabetics and adverse events. Of the 55 patients, 10 died of non-pacemaker-related complications, six had the devices removed and two could not be reached. The remaining 37 patients had the device activated for a mean of 45 months. Both per protocol and ITT analysis demonstrated that TSS, hospitalization days and the use of medications were all significantly reduced at 1 year and were sustained beyond 3 years. Average TSS decreased by 62.5% for the 37 patients completing 3 years of GES. At implantation, 15/37 patients required nutritional support and only five continued beyond 3 years. Mean HbA1c level in diabetics was significantly reduced from 9.5 to 7.9% at 3 years. We conclude that a significant improvement in symptoms and all measures of clinical outcome can be maintained for greater than 3 years with GES in patients with refractory gastroparesis.

Adult↗
PubMed2006

Treatment of gastroparesis: a multidisciplinary clinical review.

This clinical review on the treatment of patients with gastroparesis is a consensus document developed by the American Motility Society Task Force on Gastroparesis. It is a multidisciplinary effort with input from gastroenterologists and other specialists who are involved in the care of patients with gastroparesis. To provide practical guidelines for treatment, this document covers results of published research studies in the literature and areas developed by consensus agreement where clinical research trials remain lacking in the field of gastroparesis.

Consensus Statements as Topic↗
PubMed2005

Efficiency and efficacy of multi-channel gastric electrical stimulation.

Gastric electrical stimulation (GES) using single channel has been under investigation for its therapeutic potential for gastroparesis. The aim of this study was to study the efficacy and efficiency of multi-channel GES in accelerating gastric emptying in dogs. The study was performed in eight dogs, and gastric emptying of liquid was assessed in three randomized sessions of control, one-channel GES and four-channel GES. It was found that (i) GES of both one-channel and four-channel was able to completely entrain the slow waves in the entire stomach. However, the stimulation energy required by four-channel GES was only 1% of that required by one-channel GES. (ii) Four-channel, but not one-channel, GES significantly and substantially accelerated gastric emptying. An increase of 121.0 and 93.9% was noted with four-channel GES at 30 and 60 min after the meal, respectively. It was concluded that four-channel GES is substantially more efficient and effective than conventional single-channel GES in improving gastric emptying. It is worthy to explore its therapeutic potential for gastroparesis in clinical settings.

Animals↗
PubMed2004

Effect of high-frequency gastric electrical stimulation on gastric myoelectric activity in gastroparetic patients.

The aim of this study was to investigate the effect of gastric electrical stimulation (GES) on gastric myoelectric activity (GMA) and to identify possible mechanisms that could help explain how high-frequency GES is effective in treating nausea and vomiting associated with gastroparesis. Fifteen gastroparetic patients who received high-frequency GES were enrolled. Two pairs of temporary pacing wires were implanted on the serosa of the stomach along the greater curvature during surgery for placement of the permanent stimulation device. Two-channel serosal recordings of GMA before and during GES were measured. A gastric emptying test and severity of nausea and vomiting were assessed at baseline and at 3 months of GES. Power spectral and cross correlation analyses revealed that impaired propagation of slow waves (50%), tachygastria (30%) and abnormal myoelectric responses to a meal (50%) were the main abnormalities observed at baseline. GES with a high frequency significantly enhanced the slow wave amplitude and propagation velocity, and resulted in a significant improvement in nausea and vomiting but did not entrain the gastric slow wave or improve gastric emptying after 3 months of GES.

Adult↗
PubMed2004

Higher carotid-radial pulse wave velocity in healthy offspring of patients with Type 2 diabetes.

AIMS: To determine whether carotid-radial pulse wave velocity (crPWV), a simple non-invasive measurement of muscular artery structure and function, is increased in offspring of patients with Type 2 diabetes compared with well-matched controls with no family history of diabetes. Serum levels of intercellular adhesion molecule-1 (sICAM-1) were also examined. METHODS: Offspring (n = 19, M = 8) were recruited via contact with patients attending clinics. Controls (n = 19, M = 8) were recruited by advertisement. crPWV was measured using COMPLIOR. Blood pressure and heart rate were determined and fasting blood taken for measurement of metabolic and endothelial parameters. RESULTS: Offspring and controls were well matched [mean (sd)] for age [33.1 (9.6) vs. 32.8 (9.5) years], body mass index [24.8 (4.9) vs. 24.3 (3.4) kg/m2], waist circumference [78.3 (2.3) vs. 76.3 (2.5) cm], and systolic blood pressure [120 (9.3) vs. 119 (14.2) mmHg]. crPWV was 10% higher in the offspring [9.94 (1.3) m/s] compared with controls [9.01 (1.2) m/s, P = 0.02] despite similar pulse pressure [52 (10.5) vs. 53.5 (9.3) mmHg] and resting heart rate [71 (8.7) vs. 69 (14.0) beats/min]. They also showed a trend toward higher sICAM-1 [217 (55) vs. 188 (40) ng/ml, P = 0.07] concentrations which were also strongly correlated to crPWV in offspring (r = 0.63, P = 0.004). CONCLUSIONS: Vascular dysfunction in the form of increased muscular artery stiffness is present from an early stage in subjects at higher risk of developing diabetes. This may be secondary to impaired activation of endothelial signalling pathways in the context of inherited insulin resistance.

Adult↗
PubMed2004

Secretory function of the esophageal mucosa in opossum: the role of cholinergic, peptidergic and histaminergic pathways.

PURPOSE: Esophageal histology in the opossum reveals numerous submucosal mucous glands closely resembling those commonly found in humans. The aim of the study was to examine the secretion of these glands using the commonest secretagogues. MATERIAL AND METHODS: The esophageal lumen in 5 male opossums was continuously perfused with saline during sixteen consecutive 5 min perfusion periods. After four initial equilibrating periods, each animal was injected (s.c.) with pentagastrin (6 microg/kg), bethanechol chloride (100 microg/kg) or histamine dihydrochloride (0.5 mg/kg). All sixteen (5 min) perfusates were assayed for protein by Lowry, mucin by PAS and viscosity using a cone/plate digital viscometer. Results were expressed as mean +/- SE. Statistical analysis was performed using paired Student's t-test. RESULTS: Administration of bethanechol resulted in a significant increase in esophageal mucin release from 2.4 +/- 0.4 to 8.0 +/- 1.2 microg/cm2/min (p < 0.01); enhancement of protein output from 8.9 +/- 2.0 to 20.4 +/- 2.9 microg/cm2/min (p < 0.01) and potentiation of specific viscosity from 7.5 +/- 0.6 to 14.4 +/- 0.8 (p < 0.01). Pentagastrin-induced release of mucin reached the maximal value of 5.5 +/- 0.7 microg/cm2/min (p < 0.01), protein output increased to 20.0 +/- 2.7 (p < 0.01) and viscosity expanded to 11.7 +/- 0.9 (p < 0.05). Histamine evoked an increase in mucin release to 3.9 +/- 0.4 microg/cm2/min (p < 0.01), protein output to 24.1 +/- 3.3 microg/cm2/min (p < 0.01) and viscosity to 12.8 +/- 1.1 (p < 0.05). CONCLUSIONS: The significant influence of cholinergic, histaminergic and peptidergic stimulation on physical and chemical properties of the esophageal secretion provides evidence for the role of these pathways in the pathophysiology of the esophageal mucosa.

Acetylcholine↗
PubMed2003

Comparison of morning and evening administration of rabeprazole for gastro-oesophageal reflux and nocturnal gastric acid breakthrough in patients with reflux disease: a double-blind, cross-over study.

AIM: To assess the effect of timing of rebeprazole (RB) 20 mg/d administration on oesophageal acid exposure and nocturnal gastric acid breakthrough (NGAB) in patients with GERD. METHODS: 20 GERD patients received two 7-day treatments of RB in the morning (a.m.) or in the evening (p.m.) hours. The regimens were randomized in a double-blind fashion and separated by a 7-day washout period. The tablets were taken 30 min before standardized meals. A combined (oesophageal & gastric) 24-hour pH monitoring was performed before and on day 7 of each treatment. RESULTS: Total oesophageal acid exposure was normalized in 10/14 (71.4%) patients with RB p.m. and in 6/15 (42.8%) with RB a.m. RB p.m. significantly decreased the nocturnal supine oesophageal acid exposure vs. RB a.m., 0.2% vs. 3.4%. The mean NGAB duration was significantly shortened with RB a.m. and p.m. vs. the baseline recording, 4.1+/-1.8 and 3.4+/-1.5 hours vs. 7.8+/-1.7 hours. CONCLUSIONS: Rabeprazole significantly reduced the NGAB duration and significantly increased the mean nocturnal gastric pH; RB p.m. normalized more effectively the total oesophageal exposure than RB-a.m.; RB p.m. provided significantly better control of nocturnal supine gastro-oesophageal reflux than a.m. dosing. These data suggest that administration of a PPI before the evening meal maximizes acid control and would be the preferred dosing schedule in GERD patients, particularly those with nocturnal symptoms.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2001

Gastric pacing is a new surgical treatment for gastroparesis.

BACKGROUND: Gastroparesis is a chronic gastric motility disorder affecting mostly young and middle-aged women who present with nausea, abdominal pain, early satiety, vomiting, fullness, and bloating. METHODS: From April 1998 to September 2000, 25 patients underwent gastric pacemaker placement. All had documented delayed gastric emptying by a radionucleotide study. Nineteen patients had diabetic gastroparesis, 3 had developed postsurgical gastroparesis, and 3 had idiopathic gastroparesis. Baseline and postoperative follow-ups were done by a self-administered questionnaire on which the patients rated the severity and frequency of nausea and vomiting. Gastric emptying times were also followed up using a radionucleotide technique. RESULTS: Both the severity and frequency of nausea and vomiting improved significantly at 3 months and was sustained for 12 months. Gastric emptying time was also numerically faster over the 12-month period. Three of the devices have been removed. One patient died of causes unrelated to the pacemaker 10 months postoperatively. CONCLUSIONS: After placement of the gastric pacemaker, patients rated significantly fewer symptoms and had a modest acceleration of gastric emptying.

Adult↗
PubMed2001

Prevalence of gastric myoelectrical abnormalities in patients with nonulcer dyspepsia and H. pylori infection: resolution after H. pylori eradication.

The aims of this study were to investigate the effects of H. pylori eradication on gastric myoelectrical activity and dyspeptic symptoms. Sixty-two subjects with H. pylori infection and no active peptic ulcer participated in this study, which involved three sessions. Anti-H. pylori therapy consisting of clarithromycin and omeprazole was given for two weeks. Gastric myoelectrical activity was measured using surface electrogastrography and dyspeptic symptoms were scored at each session. A [14C] urea breath test was performed at baseline and one month after treatment. In comparison with baseline, the percentage of normal slow waves was significantly increased and the mean total symptom score was significantly reduced one and three months after therapy (P < 0.05). Approximately 40% of patients with nonulcer dyspepsia' symptoms and H. pylori infection have abnormal gastric myoelectrical activity, which may be normalized following the eradication of H. pylori infection. The normalization of gastric myoelectrical activity may be one explanation for the significant symptom improvement in this subset of the dyspepsia population after H. pylori eradication.

Adult↗
PubMed2001

Effects of a motilin receptor agonist (ABT-229) on upper gastrointestinal symptoms in type 1 diabetes mellitus: a randomised, double blind, placebo controlled trial.

INTRODUCTION: Erythromycin, a motilin agonist, is a potent prokinetic. ABT-229 is a specific motilin agonist that dose dependently accelerates gastric emptying. Dyspepsia and gastroparesis are common problems in type 1 diabetes mellitus. We aimed to evaluate the efficacy of ABT-229 in symptomatic diabetic patients with and without delayed gastric emptying. METHODS: Patients with type 1 diabetes and postprandial symptoms were randomised (n=270). Based on a validated C(13) octanoic acid breath test, patients were assigned to either the delayed or normal gastric emptying strata. Patients received one of four doses of ABT-229 (1.25, 2.5, 5, or 10 mg twice daily before breakfast and dinner) or placebo for four weeks following a two week baseline. A self report questionnaire measured symptoms on visual analogue scales; the primary outcome was assessment of change in the total upper abdominal symptom severity score (range 0-800 mm) from baseline to the final visit. RESULTS: The treatment arms were similar regarding baseline characteristics. There was symptom improvement on placebo and a similar level of improvement on active therapy for the upper abdominal discomfort severity score (mean change from baseline -169, -101, -155, -143, and -138 mm for placebo, and 1.25, 2.5, 5, and 10 mg ABT-229, respectively, at four weeks by intent to treat). The results were not significantly different in those with and without delayed gastric emptying. The severity of bloating, postprandial nausea, epigastric discomfort, heartburn, and acid regurgitation worsened dose dependently in a greater number of patients receiving ABT-229 than placebo. Overall, 63% of patients on placebo reported a good or excellent global response, and this was not different from the active treatment arms. CONCLUSIONS: The motilin agonist ABT-229 was not efficacious in the relief of postprandial symptoms in diabetes mellitus in the presence or absence of delayed gastric emptying.

Adolescent↗
PubMed2000

Artifact reduction in electrogastrogram based on empirical mode decomposition method.

Severe contamination of the gastric signal in electrogastrogram (EGG) analysis by respiratory, motion, cardiac artifacts, and possible myoelectrical activity from other organs, poses a major challenge to EGG interpretation and analysis. A generally applicable method for removing a variety of artifacts from EGG recordings is proposed based on the empirical mode decomposition (EMD) method. This decomposition technique is adaptive, and appears to be uniquely suitable for nonlinear, non-stationary data analysis. The results show that this method, combined with instantaneous frequency analysis, effectively separate, identify and remove contamination from a wide variety of artifactual sources in EGG recordings.

Artifacts↗
PubMed2000

Application of combined genetic algorithms with cascade correlation to diagnosis of delayed gastric emptying from electrogastrograms.

The current standard method (radioscintigraphy) for the diagnosis of delayed gastric emptying (GE) of a solid meal involves radiation exposure and considerable expense. Based on combining genetic algorithms with the cascade correlation learning architecture, a neural network approach is proposed for the diagnosis of delayed GE from electrogastrograms (EGGs). EGGs were measured by placing surface electrodes on the abdominal skin over the stomach in 152 patients with suspected gastric motility disorders for 30 min in the fasting state and for 2 h after a standard test meal. The GE rate of the stomach was simultaneously monitored after the meal using radioscintigraphy. Five spectral parameters of EGG data in each patient were used as the inputs to a classifier. The classifier was designed by using genetic algorithms in conjunction with the cascade correlation learning architecture. The main advantage of this technique over the back-propagation (BP) for supervised learning is that it can automatically develop the architecture of neural networks to give a suitable network size for a specific problem. The resulted neural network with three hidden units exhibits 83% correct classification for the EGG data, and has comparable performance with the BP network. This study demonstrates the potential of the neural network approach based on combined genetic algorithms with cascade correlation for diagnosis of gastric emptying from the EGG.

Algorithms↗
PubMed2000

Postprandial response of gastric slow waves: correlation of serosal recordings with the electrogastrogram.

Controversial interpretations have been given to the postprandial increase in the dominant power (amplitude) of the electrogastrogram (EGG). The aim of this study was to find an appropriate interpretation of the postprandial EGG power changes. Simultaneous serosal and cutaneous recordings of gastric myoelectrical activity were made in 11 patients with gastroparesis in the fasting state and after the ingestion of 8 oz of water. The dominant frequency and corresponding power of the recording before and after water were computed using the power spectral analysis method. It was found that the dominant frequency of the EGG was the same as that of the serosal recording in 10 patients. One patient showed a substantial amount of dysrhythmia and no obvious dominant frequency was noted. A decrease in the dominant frequency was found in these 10 patients after the ingestion of water. Tachygastria of higher than 4 cycles/min was observed in one of 11 patients both in the prewater and postwater states. Consistent changes in amplitude after a drink of water were noted in both serosal recording and EGG. Statistical analysis demonstrated that the dominant power change after water computed from the EGG was correlated with that observed in the serosal recording (r = 0.757, P = 0.007). In conclusion, exogenous stimulation, such as ingestion of water, may change the amplitude of the gastric slow wave and this change is reflected in the EGG, suggesting that the change of the slow-wave amplitude is an important contributing factor to the postprandial change in the EGG dominant power.

Adult↗
PubMed2000

Mechanisms of oesophageal mucosal defence.

The integrity of the oesophageal mucosa depends upon an equilibrium between aggressive factors, predominantly acid and pepsin, and protective mechanisms. Protective mechanisms operate within the oesophageal mucosa as pre-epithelial, epithelial and post-epithelial defences. Only the protective components of the oesophageal pre-epithelial defence can be tested in vivo in humans. It has been recently demonstrated that human oesophageal submucosal glands elaborate mucous secretion rich in bicarbonate and non-bicarbonate buffers, mucin, prostaglandin E(2), epidermal growth factor (EGF) and transforming growth factor alpha (TGFalpha). This oesophageal secretion, accompanied by similarly protective factors within the swallowed saliva, defines the protective potential of the oesophageal pre-epithelial defence that exists in the form of a mucus-buffer layer covering the oesophageal mucosa and which retards the back-diffusion of hydrogen ions. It has also been demonstrated that patients with severe erosive reflux oesophagitis exhibit qualitative impairment in both the salivary and oesophageal components of the oesophageal pre-epithelial defence. Furthermore, patients with endoscopically negative gastro-oesophageal reflux disease have a significantly stronger oesophageal pre-epithelial defence than patients with erosive reflux oesophagitis. On the other hand, African-Americans, who are less likely to develop erosive reflux oesophagitis, have a stronger oesophageal pre-epithelial defence than do Caucasians. The salivary component of the oesophageal pre-epithelial defence can be enhanced by mastication and the administration of cisapride, whereas oesophageal secretion can only be significantly augmented by cisapride.

Animals↗
PubMed2000

Noninvasive feature-based detection of delayed gastric emptying in humans using neural networks.

Radioscintigraphy is currently the gold standard for gastric emptying test which involves radiation exposure and is considerably expensive. We present a feature-based detection approach using neural networks for the noninvasive diagnosis of delayed gastric emptying from the cutaneous electrogastrogram (EGG). Simultaneous recordings of the EGG and scintigraphic gastric emptying test were made in 152 patients with symptoms suggestive of delayed gastric emptying. Spectral analyses were performed to derive EGG parameters which were used as the input of the neural network. The result of scintigraphic gastric emptying was used as the gold standard for the training and testing of the neural network. A correct classification of 85% (a specificity of 89% and a sensitivity of 82%) was achieved using the proposed method.

Adolescent↗
PubMed2000

Salivary and gastric epidermal growth factor in patients with Zollinger-Ellison syndrome: its protective potential.

OBJECTIVE: Evidence is accumulating that epidermal growth factor (EGF) is a major molecule contributing to the maintenance of the integrity of the upper alimentary tract mucosa before and after injury by acid and pepsin. Patients with Zollinger-Ellison Syndrome (ZES) typically have hypersecretion of acid and pepsin; however, the concentration and rate of secretion of salivary and gastric EGF that could counteract these potentially aggressive factors are unknown. Accordingly, this study was conducted to determine whether EGF affords mucosal protection in ZES patients. METHODS: The concentration and output of salivary (sEGF) and gastric epidermal growth factor (gEGF) were measured in eight patients with ZES and the results compared to those in 17 patients with nonulcer dyspepsia (NUD), serving as a control group. All patients had normal esophageal and gastric mucosa as determined by endoscopy. Total saliva was collected during 1-h parafilm- and 1-h pentagastrin/parafilm-stimulated conditions, as well as basal and pentagastrin-stimulated gastric juice. The concentration and output of EGF were determined by radioimmunoassay. RESULTS: The concentration of EGF in saliva collected from ZES patients after parafilm chewing was significantly higher compared to that in NUD patients (4.61 +/- 0.59 vs 2.75 +/- 0.50 ng/ml, p < 0.05). The concentration of EGF in saliva collected after pentagastrin stimulation in ZES patients was also significantly higher than in NUD patients (4.37 +/- 0.73 vs 2.22 +/- 0.37 ng/ml, p < 0.05). Salivary EGF output during parafilm chewing in ZES and NUD were similar (68 +/- 6.4 vs 109 +/- 25.2 ng/h). Salivary EGF output after administration of pentagastrin in ZES and NUD was also similar (66 +/- 6.1 vs 132 +/- 45.4 ng/h). Basal EGF output in the gastric juice of patients with ZES was 3-fold higher than in patients with NUD (801 +/- 73 vs 271 +/- 32 ng/h, p < 0.01). Pentagastrin-stimulated EGF output was similar in both groups (705 +/- 92 vs 675 +/- 168 ng/h). CONCLUSIONS: Patients with ZES have a significantly higher EGF concentration in saliva and EGF output in basal gastric juice. This elevated content of salivary and gastric EGF in ZES patients may play a protective role in preventing the development of reflux esophagitis and gastric ulcer under the impact of gastric acid and pepsin hypersecretion.

Adult↗
PubMed2000

Assessment of gastric emptying using a low fat meal: establishment of international control values.

OBJECTIVE: The diagnosis of gastroparesis implies delayed gastric emptying. The diagnostic gold standard is scintigraphy, but techniques and measured endpoints vary widely among institutions. In this study, a simplified scintigraphic measurement of gastric emptying was compared to conventional gastric scintigraphic techniques and normal gastric emptying values defined in healthy subjects. METHODS: In 123 volunteers (aged 19-73 yr, 60 women and 63 men) from 11 centers, scintigraphy was used to assess gastric emptying of a 99Tc-labeled low fat meal (egg substitute) and percent intragastric residual contents 60, 120, and 240 min after completion of the meal. In 42 subjects, additional measurements were taken every 10 min for 1 h. In 20 subjects, gastric emptying of a 99Tc-labeled liver meal was compared with that of the 99Tc-labeled low fat meal. RESULTS: Median values (95th percentile) for percent gastric retention at 60, 120, and 240 min were 69% (90%), 24% (60%) and 1.2% (10%) respectively. A power exponential model yielded similar emptying curves and estimated T50 when using images only taken at 1, 2 and 4 h, or with imaging taken every 10 min. Gastric emptying was initially more rapid in men but was comparable in men and women at 4 h; it was faster in older subjects (p < 0.05) but was independent of body mass index. CONCLUSIONS: This multicenter study provides gastric emptying values in healthy subjects based on data obtained using a large sample size and consistent meal and methodology. Gastric retention of >10% at 4 h is indicative of delayed emptying, a value comparable to those provided by more intensive scanning approaches. Gastric emptying of a low fat meal is initially faster in men but is comparable in women at 4 h; it is also faster in older individuals but is independent of body mass.

Adult↗