Bayesian hierarchical methods to interpret the (13)C-octanoic acid breath test for gastric emptying

BACKGROUND

The (13)C-octanoic acid breath test is a convenient method for assessing gastric emptying (GE). Success depends on obtaining a well-characterized time profile of the excretion of label in breath, which may not be the case if GE is delayed.

AIMS

To use Bayesian techniques in conjunction with hierarchical modelling as a method to increase the success of the modelling process.

METHODS

Retrospective analysis of 164 individual breath tests using the WinBUGS program. The approach was tested by analysing the complete dataset simultaneously, and also as individual studies.

RESULTS

The time required for Bayesian modelling was comparable with that needed for the usual methods. The results obtained were almost identical to those obtained from conventional modelling for well-behaved breath tests, but much more realistic in cases where the experimental data was poor, or when GE was delayed.

CONCLUSIONS

The use of Bayesian estimation of the parameters of the (13)C-octanoic acid breath test is demonstrated. By adopting a hierarchical model, realistic values for the lag phase and half-emptying time were obtained in situations when conventional parameter estimation failed. This is particularly relevant when GE is unexpectedly delayed. We recommend that WinBUGS become the method of choice for analysing breath test data.

Assessment of symptoms during gastric emptying scintigraphy to correlate symptoms to delayed gastric emptying

BACKGROUND

Symptoms of gastroparesis based on patient recall correlate poorly with gastric emptying. The aim of this study is to determine if symptoms recorded during gastric emptying scintigraphy (GES) correlate with gastric emptying and with symptoms based on patient recall.

METHODS

Patients undergoing GES completed the Patient Assessment of GI Symptoms (PAGI-SYM) assessing symptoms over the prior 2 weeks and a questionnaire for which patients graded six symptoms during GES. A Symptom Severity Index (SSI) represented the mean of six symptoms at each time point.

KEY RESULTS

A total of 560 patients underwent GES for clinical evaluation of symptoms. Of 388 patients included in the study: 232 patients had normal GES (NGES), 156 delayed GES (DGES), and 11 rapid GES (RGES). Symptom severity index increased pre to postprandial for each group: NGES: 0.51 +/- 0.07 to 0.92 +/- 0.03, DGES: 0.60 +/- 0.09 to 1.13 +/- 0.05, and RGES: 0.56 +/- 0.12 to 0.79 +/- 0.13. Delayed gastric emptying scintigraphy patients had a higher postprandial SSI than NGES patients (1.13 +/- 0.05 vs 0.92 +/- 0.03, P < 0.05). Postprandial symptoms of stomach fullness (1.9 +/- 0.12 vs 1.5 +/- 0.09; P = 0.011), bloating (1.4 +/- 0.11 vs 1.1 +/- 0.09; P = 0.033), and abdominal pain (1.1 +/- 0.08 vs 0.7 +/- 0.12; P = 0.012) were higher in DGES than NGES. Symptom severity based on PAGI-SYM for 2 weeks prior to GES correlated with symptoms during the test for nausea (NGES, r = 0.61; DGES, r = 0.70), stomach fullness (NGES, r = 0.47; DGES, r = 0.60), and bloating (NGES, r = 0.62, DGES, r = 0.66).

CONCLUSIONS & INFERENCES

Stomach fullness, bloating, and abdominal pain recorded during GES were higher in patients with delayed gastric emptying than in patients with normal gastric emptying. Symptoms recorded during GES correlated with those during daily life by patient recall.

Gastric emptying of enterally administered liquid meal in conscious rats and during sustained anaesthesia

BACKGROUND

Gastric motility studies are frequently conducted with anaesthetized animal models. Some studies on the same animal species have reported differences in vagal control of the stomach that could not be explained solely by slightly different experimental conditions. A possible limitation in the comparison between similar studies relates to the use of different anaesthetic agents. Furthermore, anaesthetic effects may also limit generalizations between mechanistic studies of gastric function and the gastric function of conscious animals. In the present study, we used the [(13)C]-breath test following a liquid mixed-nutrient test meal (Ensure), 1 ml) with the aim to investigate the rate of gastric emptying in animals that were either conscious or anaesthetized with either Inactin or urethane.

METHODS

One week after determining the maximum (13)CO(2) concentration, time to peak [(13)C] recovery and gastric half emptying time in control, conscious rats, we repeated the experiment in the same rats anaesthetized with Inactin or urethane.

KEY RESULTS

Our data show that Inactin anaesthesia prolonged the time to peak [(13)C] recovery but did not significantly reduce the maximum (13)CO(2) concentration nor delay gastric half emptying time. Conversely, urethane anaesthesia resulted in a significant slowing of all parameters of gastric emptying as measured by the maximum (13)CO(2) concentration, time to peak [(13)C] recovery and half emptying time.

CONCLUSIONS & INFERENCES

Our data indicate that Inactin(R) anaesthesia does not significantly affect gastric emptying while urethane anaesthesia profoundly impairs gastric emptying. We suggest that Inactin(R), not urethane, is the more suitable anaesthetic for gastrointestinal research.

The assessment of regional gut transit times in healthy controls and patients with gastroparesis using wireless motility technology

BACKGROUND

Wireless pH and pressure motility capsule (wireless motility capsule) technology provides a method to assess regional gastrointestinal transit times.

AIMS

To analyse data from a multi-centre study of gastroparetic patients and healthy controls and to compare regional transit times measured by wireless motility capsule in healthy controls and gastroparetics (GP).

METHODS

A total of 66 healthy controls and 34 patients with GP (15 diabetic and 19 idiopathic) swallowed wireless motility capsule together with standardized meal (255 kcal). Gastric emptying time (GET), small bowel transit time (SBTT), colon transit time (CTT) and whole gut transit time (WGTT) were calculated using the wireless motility capsule.

RESULTS

Gastric emptying time, CTT and WGTT but not SBTT were significantly longer in GP than in controls. Eighteen percent of gastroparetic patients had delayed WGTT. Both diabetic and idiopathic aetiologies of gastroparetics had significantly slower WGTT (P < 0.0001) in addition to significantly slower GET than healthy controls. Diabetic gastroparetics additionally had significantly slower CTT than healthy controls (P = 0.0054).

CONCLUSIONS

In addition to assessing gastric emptying, regional transit times can be measured using wireless motility capsule. The prolongation of CTT in gastroparetic patients indicates that dysmotility beyond the stomach in GP is present, and it could be contributing to symptom presentation.

Stomach dysfunction in diabetes mellitus: emerging technology and pharmacology

Gastroparesis and other types of gastric dysfunction result in substantial morbidity in diabetes patients. The pathophysiology of these disorders is incompletely understood. This article reviews techniques applicable to the assessment of gastric function in diabetes patients, including the measurement of emptying, accommodation, and contractility. Available treatment options are also reviewed, including novel yet unapproved serotonin 5-HT(4) agonist pharmacological treatments, as well as the role of endoscopic, surgical, and device treatments of gastroparesis.

Gastric emptying, small intestinal transit and fecal output in dystrophic (mdx) mice

Duchenne muscular dystrophy (DMD), which results from deficiency in dystrophin, a sarcolemma protein of skeletal, cardiac and smooth muscle, is characterized by progressive striated muscle degeneration, but various gastrointestinal clinical manifestations have been observed. The aim was to evaluate the possible impact of the dystrophin loss on the gastrointestinal propulsion in mdx mice (animal model for DMD). The gastric emptying of a carboxymethyl cellulose/phenol red dye non-nutrient meal was not significantly different at 20 min from gavaging between wild-type and mdx mice. The intestinal transit and the fecal output were significantly decreased in mdx versus normal animals, although the length of the intestine was similar in both animals. The present results provide evidence for motor intestinal alterations in mdx mice in in vivo conditions.

Review article: gastric electrical stimulation for gastroparesis--physiological foundations, technical aspects and clinical implications

BACKGROUND

Application of electrical stimulation to the gut, primarily the stomach, has rapidly advanced in the last two decades, from mostly animal studies to the clinical arena. Most studies focused on the use of electrical stimulation for gastroparesis, the only approved indication for such intervention.

AIM

To review the physiological basis of gastric electrical activity and the technical aspects and clinical outcome of gastric electrical stimulation (GES) for gastroparesis.

METHODS

PubMed search from 1966 to 2009, using gastroparesis and GES as search terms. Areas in focus were systematically reviewed.

RESULTS

The literature consists of open-label studies, mostly from single centres, published in the last decade. Improvement in symptoms, quality of life and nutritional status was reported by most studies. Physiologically, stimulation parameters approved in clinical practice do not regulate gastric slow wave activity and have inconsistent effect on gastric emptying. The mechanism of action of GES is not fully known, but data support modulation of gastric biomechanical activity and afferent neural mechanisms.

CONCLUSIONS

Gastric electrical stimulation is a helpful intervention in recalcitrant gastroparesis. Controlled studies and better understanding of mechanisms of action of electrical stimulation are needed to evaluate further the clinical utility of this intervention and to exploit its therapeutic potential better.

A review of exenatide as adjunctive therapy in patients with type 2 diabetes

Background

Incretin glucagon-like peptide-1 (GLP-1) is a hormone released from cells in the gastrointestinal tract (GI), leading to glucose-dependent insulin release from the pancreas. It also suppresses postprandial hyperglycemia, glucagon secretion and slows gastric emptying. Exenatide (EXE), a functional analog of human GLP-1, was approved by the US FDA in April 2005.

Objective

This article reviews current primary literature on the clinical efficacy and safety of EXE in the treatment of type 2 diabetes mellitus (DM) and describes the pharmacokinetics, pharmacodynamics, dosing and administration of EXE.

Methods

English-language articles were identified through a search of MEDLINE (1966 to March 2009), International Pharmaceutical Abstracts (1970 to present), and Cochrane Database of Systemic Reviews (1995 to March 2009). Search terms included EXE, diabetes mellitus, postprandial hyperglycemia, gastric emptying, glucagon, pharmacokinetics and pharmacodynamics. Articles were selected for review if their designs were randomized, blinded and of controlled design that focused on clinical outcomes of patients with type 2 DM.

Results

EXE is administered subcutaneously in the thigh, abdomen or upper arm within the 60-minute period before the morning and evening meals. Its C_max is reached within 2.1 hours, and its T_1/2 in 2.4 hours. EXE’s metabolism is primarily through the kidneys. For the patients who received EXE 10 μg SC BID in three, 30-week, placebo-controlled studies with background sulfonylureas (SUs), metformin (MET), or SU + MET, there were significant reductions in HbA_1c (0.77 to 0.86%), fasting plasma glucose (0.6 mmol/L) and body weight (1.6 to 2.8 kg) (P ≤ 0.05 vs PCB) that were sustained in patients who completed two open-label phase trials with an additional 52 weeks of therapy. The use of thiazolidinediones was associated with a slight advantage over EXE in improving HbA_1c along with increased weight gain; those who received EXE lost weight, but experienced more GI adverse effects. Patients who received EXE lost significant body weight while patients who received insulin gained weight. Patients receiving insulin had lower fasting, prelunch and predinner glucose excursions while patients in the EXE groups had lower postprandial glucose levels. Nausea was most frequently (>20%) reported in patients receiving the highest dose of EXE (10 μg SC BID vs 5 μg SC BID).

Conclusions

EXE at the dose of 10 μg SC BID has been proven to decrease HbA_lc by 1.3% ± 0.1% and decrease body weight by up to 5.3 ± 0.8 kg at week 82. Nausea was the most frequently reported adverse event (>20%) especially in patients being treated with EXE 10 μg SC BID. EXE can be safely added to MET therapy, SU therapy or MET + SU combination to effectively target glycemic goals in patients with type 2 DM. Long-term, head-to-head studies assessing the effect of the EXE ± oral agents/insulins in patients with HbA_lc ≥ 10% are still needed to fully clarify the role of EXE in poorly controlled patients with type 2 DM.

Pyloric sphincter dysfunction in nNOS-/- and W/Wv mutant mice: animal models of gastroparesis and duodenogastric reflux

BACKGROUND & AIMS

Nitrergic nerves and interstitial cells of Cajal (ICC) have been implicated in the regulation of pyloric motility. The purpose of these studies was to define their roles in pyloric function in vivo.

METHODS

Pyloric sphincter manometry was performed in wild-type controls, neuronal nitric oxide synthase-deficient (nNOS(-/-)) mice, and ICC-deficient W/W(v) mice, and the effect of deafferented cervical vagal stimulation was examined.

RESULTS

Mice showed a distinct approximately 0.6-mm-wide zone of high pressure at the antroduodenal junction, representing the pyloric sphincter. In wild-type controls, the pylorus exhibited tonic active pressure of 12.4 +/- 1.6 mm Hg with superimposed phasic contractions. The motility indices, minute motility index, and total myogenic activity were reduced by vagal stimulation, and the reduction was antagonized by the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). In nNOS(-/-) mice, pyloric basal tone, minute motility index, and total myogenic activity were not significantly different from those in controls, but vagal stimulation paradoxically increased pyloric motility. In contrast, the W/W(v) mice had significantly reduced resting pyloric pressure that was suppressed by vagal stimulation in an L-NAME-sensitive manner. The stomachs of fasted nNOS(-/-) mice showed solid food residue and bezoar formation, while W/W(v) mice showed bile reflux.

CONCLUSIONS

In nNOS(-/-) mice, loss of nitrergic pyloric inhibition leads to gastric stasis and bezoars. In contrast, basal pyloric hypotension with normal nitrergic inhibition predisposes W/W(v) mice to duodenogastric bile reflux.

Lack of relationship between chronic upper abdominal symptoms and gastric function in functional dyspepsia

To determine the relationship between gastric function and upper abdominal sensations we studied sixty FD patients (43 female). All patients underwent three gastric function tests: (13)C octanoic gastric emptying test, three-dimensional ultrasonography (proximal and distal gastric volume), and the nutrient drink test. Upper abdominal sensations experienced in daily life were scored using questionnaires. Impaired proximal gastric relaxation (23%) and a delayed gastric emptying (33%) are highly prevalent in FD patients; however, only a small overlap exists between the two pathophysiologic disorders (5%). No relationship was found between chronic upper abdominal symptoms and gastric function (proximal gastric relaxation, gastric emptying rate, or drinking capacity) (all P > 0.01). Proximal gastric relaxation or gastric emptying rate had no effect on maximum drinking capacity (P > 0.01). The lack of relationship between chronic upper abdominal sensations and gastric function questions the role of these pathophysiologic mechanisms in the generation of symptoms.

Diabetes and the enteric nervous system

Diabetes is associated with several changes in gastrointestinal (GI) motility and associated symptoms such as nausea, bloating, abdominal pain, diarrhoea and constipation. The pathogenesis of altered GI functions in diabetes is multifactorial and the role of the enteric nervous system (ENS) in this respect has gained significant importance. In this review, we summarize the research carried out on diabetes-related changes in the ENS. Changes in the inhibitory and excitatory enteric neurons are described highlighting the role of loss of inhibitory neurons in early diabetic enteric neuropathy. The functional consequences of these neuronal changes result in altered gastric emptying, diarrhoea or constipation. Diabetes can also affect GI motility through changes in intestinal smooth muscle or alterations in extrinsic neuronal control. Hyperglycaemia and oxidative stress play an important role in the pathophysiology of these ENS changes. Antioxidants to prevent or treat diabetic GI motility problems have therapeutic potential. Recent research on the nerve-immune interactions demonstrates inflammation-associated neurodegeneration which can lead to motility related problems in diabetes.

Does delayed gastric emptying really cause symptoms in functional dyspepsia?

When the glove does fit, you should not acquit

Functional dyspepsia, delayed gastric emptying, and impaired quality of life

BACKGROUND

It remains controversial as to whether delayed gastric emptying in functional dyspepsia is associated with a specific symptom pattern, and it is unknown if gastric emptying in functional dyspepsia is a driver of impaired health related quality of life (HRQOL). We aimed to evaluate the relationship between functional dyspepsia symptoms, gastric emptying, and HRQOL.

METHODS

US patients (n=864; mean age 44 years (range 18-82); 74% female) with functional dyspepsia, as defined by Rome II criteria, were enrolled into one of four clinical trials. All patients had a baseline scintigraphic assessment of gastric emptying of an egg substitute meal, and the trials were stratified on this assessment. Delayed gastric emptying was defined as having at least 6.3% residual volume at four hours. A total of 290 (34%) patients had delayed gastric emptying. HRQOL was assessed by the SF 36 and Nepean dyspepsia index (NDI).

RESULTS

Postprandial fullness was independently associated with delayed gastric emptying but the association was weak (odds ratio (OR) 1.98 (95% confidence interval (CI) 1.02, 3.86); p=0.04). No independent association was seen with epigastric pain, early satiety, nausea, or bloating. Mean SF 36 physical composite score (PCS) was 42.3 (95% CI 41.6, 43.0) and the mean SF 36 mental composite score (MCS) was 46.8 (95% CI 46.0, 47.5); both mean scores were significantly lower than age and sex adjusted national norms of 50 (p<.0001). Female sex, increasing age, and higher symptom scores for fullness, epigastric pain, and nausea were each independently associated with decreased PCS scores (all p<0.05). Higher baseline nausea symptom score, lower gastric emptying rates at one hour, and lower body mass index were associated with decreased MCS (all p<0.05). Female sex, epigastric pain, and nausea, but not gastric emptying, were associated with an impaired score on the NDI. However, the magnitude of the significant associations were all small.

CONCLUSIONS

In patients with functional dyspepsia selected for a clinical trial programme, gastric emptying did not usefully stratify them symptomatically. Quality of life of patients with functional dyspepsia enrolled in this clinical trial programme was significantly impaired but this was not explained by delayed gastric emptying.

Antro-pyloro-duodenal motor responses to gastric and duodenal nutrient in critically ill patients

BACKGROUND

Gastric emptying is frequently delayed in critical illness which compromises the success of nasogastric nutrition. The underlying motor dysfunctions are poorly defined.

AIMS

To characterise antro-pyloro-duodenal motility during fasting, and in response to gastric and duodenal nutrient, as well as to evaluate the relationship between gastric emptying and motility, in the critically ill.

SUBJECTS

Fifteen mechanically ventilated patients from a mixed intensive care unit; 10 healthy volunteers.

METHODS

Antro-pyloro-duodenal pressures were recorded during fasting, after intragastric administration (100 ml; 100 kcal), and during small intestinal infusion of liquid nutrient (6 hours; 1 kcal/min). Gastric emptying was measured using a (13)C octanoate breath test.

RESULTS

In healthy subjects, neither gastric nor small intestinal nutrient affected antro-pyloro-duodenal pressures. In patients, duodenal nutrient infusion reduced antral activity compared with both fasting and healthy subjects (0.03 (0-2.47) waves/min v 0.14 (0-2.2) fasting (p = 0.016); and v 0.33 (0-2.57)/min in healthy subjects (p = 0.005)). Basal pyloric pressure and the frequency of phasic pyloric pressure waves were increased in patients during duodenal nutrient infusion (3.12 (1.06) mm Hg; 0.98 (0.13)/min) compared with healthy subjects (-0.44 (1.25) mm Hg; p<0.02 after 120 minutes; 0.29 (0.15)/min; p = 0.0002) and with fasting (-0.06 (1.05) mm Hg; p<0.03 after 160 minutes; 0.49 (0.13)/min; (p = 0.0001). Gastric emptying was delayed in patients (gastric emptying coefficient 2.99 (0.2) v 3.47 (0.1); p = 0.015) and inversely related to the number of pyloric pressure waves (r = -0.563, p = 0.029).

CONCLUSIONS

Stimulation of pyloric and suppression of antral pressures by duodenal nutrient are enhanced in the critically ill and related to decreased gastric emptying.

Gastric motor effects of peptide and non-peptide ghrelin agonists in mice in vivo and in vitro

BACKGROUND AND AIMS

The gastroprokinetic activities of ghrelin, the natural ligand of the growth hormone secretagogue receptor (GHS-R), prompted us to compare the effect of ghrelin with that of synthetic peptide (growth hormone releasing peptide 6 (GHRP-6)) and non-peptide (capromorelin) GHS-R agonists both in vivo and in vitro.

METHODS

In vivo, the dose dependent effects (1-150 nmol/kg) of ghrelin, GHRP-6, and capromorelin on gastric emptying were measured by the 14C octanoic breath test which was adapted for use in mice. The effect of atropine, N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME), or D-Lys3-GHRP-6 (GHS-R antagonist) on the gastroprokinetic effect of capromorelin was also investigated. In vitro, the effect of the GHS-R agonists (1 microM) on electrical field stimulation (EFS) induced responses was studied in fundic strips in the absence and presence of L-NAME.

RESULTS

Ghrelin, GHRP-6, and capromorelin accelerated gastric emptying in an equipotent manner, with bell-shaped dose-response relationships. In the presence of atropine or l-NAME, which delayed gastric emptying, capromorelin failed to accelerate gastric emptying. D-Lys3-GHRP-6 also delayed gastric emptying but did not effectively block the action of the GHS-R agonists, but this may be related to interactions with other receptors. EFS of fundic strips caused frequency dependent relaxations that were not modified by the GHS-R agonists. L-NAME turned EFS induced relaxations into cholinergic contractions that were enhanced by ghrelin, GHRP-6, and capromorelin.

CONCLUSION

The 14C octanoic breath test is a valuable technique to evaluate drug induced effects on gastric emptying in mice. Peptide and non-peptide GHS-R agonists accelerate gastric emptying of solids in an equipotent manner through activation of GHS receptors, possibly located on local cholinergic enteric nerves.

Influence of erythromycin on gastric emptying and meal related symptoms in functional dyspepsia with delayed gastric emptying

BACKGROUND AND AIMS

Although delayed gastric emptying is considered a major pathophysiological mechanism in functional dyspepsia, the efficacy of prokinetic drugs has not been established. Recent studies using macrolide prokinetics were negative but receptor desensitisation may have played a role. The aim of the present study was to evaluate the influence on meal induced symptoms of acutely administered erythromycin in patients with gastroparesis.

METHODS

In 20 patients with functional dyspepsia, gastric emptying was studied twice using the (14)C octanoic acid and (13)C glycin breath test to establish the reproducibility of the test. Breath samples were taken before the meal and at 15 minute intervals for a period of 240 minutes postprandially. At each breath sampling, the patient was asked to grade the intensity (0-3) of six dyspeptic symptoms. Twenty four patients (three men, mean age 43.5 (3) years) with dyspeptic symptoms and delayed gastric emptying were studied twice after pretreatment with saline or erythromycin intravenously.

RESULTS

Meal related symptom severity scores were reproducible. Treatment with erythromycin significantly enhanced solid and liquid gastric emptying (t(1/2) 146 (27) v 72 (7) minutes, respectively (p<0.01), and 87 (6) v 63 (5) minutes (p<0.001)). Only the severity of bloating was significantly improved by erythromycin (23 (3.9) v 14.5 (2.7); p<0.01); all other symptoms and the cumulative meal related symptom score were not altered by erythromycin.

CONCLUSIONS

In a setting where desensitisation played no role, erythromycin enhanced gastric emptying was not associated with a beneficial effect on meal related symptom severity.

Gastric Emptying, CCK Release, and Satiety in Weight-Stable Obese Subjects

Scintigraphic gastric emptying studies are far from conclusive in obesity. The aim was to investigate gastric emptying and CCK release in weight-stable obese subjects on their usual diet and to study the impact of factors known to determine gastric emptying. Patients entering a weight reduction program were asked to participate in a study examining gastric emptying by scintigraphy and CCK release in response to a meal with questionnaires on feelings of satiety. Forty-five patients (9 M, 36 F) with a mean (SD) BMI of 37.0 (4.0) kg/m² entered the study. The mean T₅₀ (emptying of 50%) of fluids was 20.7 (10.3) min, and that of solids 141.9 (168.3) min. The percentage emptying of solids was 34.5 (19.9)%/hr. CCK values peaked within 42 min and paralleled the subjective ratings of satiety but did not correlate with gastric emptying. Five of 45 subjects (11%) had very prolonged gastric emptying of solids; they showed higher caloric intakes and higher insulin levels. They did not differ in CCK values and ratings of satiety but scored higher in being active and awake. Without these five subjects the T₅₀ of solids was 94.3 (36.1) min, and the percentage of emptying 37.9 (18.4)%/hr. Liquid emptying was faster and solid emptying similar compared with those of normal-weight individuals. Height, fat-free mass, and waist-hip circumference were positively related to solid emptying. In weight-stable obese subjects liquid emptying was faster and solid emptying similar to those in normal-weight subjects. Higher caloric intakes and insulin levels were present in subjects with prolonged solid emptying; they also appeared more vigilant. Body size and composition were the only determinants suggesting a faster solid emptying in taller and muscular subjects or in subjects with more intraabdominal fat.

Symptom patterns in functional dyspepsia and irritable bowel syndrome: relationship to disturbances in gastric emptying and response to a nutrient challenge in consulters and non-consulters

BACKGROUND

Our aim was to assess the relationship between gastric motor and sensory function and symptom patterns in community subjects and patients with functional dyspepsia (FD) or irritable bowel syndrome (IBS).

METHODS

We recruited 291 asymptomatic blood donors, 151 symptomatic blood donors (recurrent abdominal pain or discomfort), and 40 patients with FD or IBS. Abdominal symptoms were assessed using the bowel disease questionnaire (BDQ) and, in addition, the most bothersome symptom complex identified (dysmotility-type, ulcer-type dyspepsia, or IBS). Gastric emptying time (GET (t(1/2), min)) was measured by (13)C-octanoic breath test and a nutrient challenge performed. Twenty randomly selected asymptomatic blood donors, 48 symptomatic blood donors (30 FD, 18 IBS), and 40 patients (23 FD, 17 IBS) had additional function testing.

RESULTS

GET (t(1/2)) was significantly (p<0.05) longer in blood donors with FD symptoms (99 (6) min) and FD patients (110 (12) min) compared with asymptomatic controls (76.7 (7) min), but was not significant in IBS blood donors or patients. Overall, 25 of 48 blood donors with symptoms and 18 of 40 patients had slow gastric emptying. GET was most delayed in subjects with predominantly dysmotility-type symptoms (167 (36) min v controls; p<0.01). Symptom intensities after a nutrient challenge were significantly higher in FD patients and symptomatic blood donors compared with asymptomatic controls; 14 of 48 blood donors with symptoms and 16 of 40 patients had a symptom response to the nutrient challenge exceeding the response (mean (2SD)) of healthy asymptomatic controls.

CONCLUSION

Gastric emptying and the global symptom response to a standardised nutrient challenge are abnormal in population based (non-health care seeking) subjects with dyspepsia.

Effect of a somatostatin analogue on gastric motor and sensory functions in healthy humans

BACKGROUND

Pharmacological approaches to alter satiation may have an impact on functional upper gastrointestinal disorders and potentially change food intake in obesity.

AIM

Our aim was to compare the effects of two doses of octreotide and placebo on postprandial symptoms, gastric accommodation, and gastric emptying using validated non-invasive techniques.

METHODS

In a randomised, parallel group, two dose, double blind, placebo controlled study, 39 healthy participants (13 per group) were randomised to 30 or 100 micro g octreotide or placebo, administered subcutaneously, 30 minutes before each study. Studies were performed on three separate days and included scintigraphic gastric emptying of solids and liquids, (99m)Tc SPECT imaging to measure fasting stomach volume and gastric accommodation following a 300 ml Ensure meal, and a standardised nutrient drink test to measure maximum tolerated volume and postprandial symptoms.

RESULTS

Relative to placebo, both doses of octreotide delayed gastric emptying of solids (not liquids), increased fasting gastric volume, reduced the change in gastric volume post meal, and decreased the sensation of fullness after a satiating meal.

CONCLUSION

The somatostatin analogue octreotide significantly alters human gastric functions, including inhibition of the normal reflex responses of gastric volume increase and emptying of the meal. These pharmacological effects suggest studies of the medication in disorders of satiation, including obesity and dyspepsia, are warranted.

13C urea breath test (UBT) in the diagnosis of Helicobacter pylori: why does it work better with acid test meals?

BACKGROUND

Acid test meals may improve the accuracy of the (13)C urea breath test (UBT). This has been attributed to changes in gastric emptying rather than to the effects of gastric pH on Helicobacter pylori urease.

AIMS

To determine whether enhancement of (13)CO(2) excretion in the UBT in H pylori infected volunteers by acidification of a test meal is due to a delay in gastric emptying.

METHODS

Urease activity in vitro was measured in intact bacteria and in bacterial homogenates. Urease activity in vivo was assessed by means of the UBT. Eleven H pylori infected subjects underwent UBTs with neutral Ensure (pH 7.0), acidified Ensure (pH 3.0), and apple juice (pH 3.0). Gastric emptying was assessed by (13)C sodium acetate breath test.

RESULTS

From pH 7 to pH 3, the in vitro urease activity of intact bacteria increased sixfold. In contrast, urease activity of bacterial homogenates was inactivated by low pH. In vivo, urease activity, as measured by the UBT 20 minutes after meal ingestion, was higher with apple juice (delta (13)CO(2)=21.1; p=0.03) and acidified Ensure (delta (13)CO(2)=25.5; p=0.01) than with neutral Ensure (delta (13)CO(2)=12.5). Gastric emptying was faster with apple juice (T(max)=36.7 (8) minutes) but not with acidified Ensure (T(max)=63.3 (5) minutes; p=0.06) than with neutral Ensure (T(max)=65.0 (3) minutes; p=0.04).

CONCLUSIONS

The higher UBT found with acidified compared with neutral test meals was independent of the emptying rates of the test meals but may have been due to medium acidity dependent activation of intra-bacterial urease in intact H pylori.

The addition of locust bean gum but not water delayed the gastric emptying rate of a nutrient semisolid meal in healthy subjects

BACKGROUND

Most of the previous studies regarding the effects of gel-forming fibres have considered the gastric emptying of liquid or solid meals after the addition of pectin or guar gum. The influence of locust bean gum, on gastric emptying of nutrient semisolid meals in humans has been less well studied, despite its common occurrence in foods. Using a standardised ultrasound method, this study was aimed at investigating if the gastric emptying in healthy subjects could be influenced by adding locust been gum, a widely used thickening agent, or water directly into a nutrient semisolid test meal.

METHODS

The viscosity of a basic test meal (300 g rice pudding, 330 kcal) was increased by adding Nestargel (6 g, 2.4 kcal), containing viscous dietary fibres (96.5%) provided as seed flour of locust bean gum, and decreased by adding 100 ml of water. Gastric emptying of these three test meals were evaluated in fifteen healthy non-smoking volunteers, using ultrasound measurements of the gastric antral area to estimate the gastric emptying rate (GER).

RESULTS

The median value of GER with the basic test meal (rice pudding) was estimated at 63%, (range 47 to 84%), (the first quartile = 61%, the third quartile = 69%). Increasing the viscosity of the rice pudding by adding Nestargel, resulted in significantly lower gastric emptying rates (p < 0.01), median GER 54%, (range 7 to 71%), (the first quartile = 48%, the third quartile = 60%). When the viscosity of the rice pudding was decreased (basic test meal added with water), the difference in median GER 65%, (range 38 to 79%), (the first quartile = 56%, the third quartile = 71%) was not significantly different (p = 0.28) compared to the GER of the basic test meal.

CONCLUSIONS

We conclude that the addition of locust bean gum to a nutrient semisolid meal has a major impact on gastric emptying by delaying the emptying rate, but that the addition of water to this test meal has no influence on gastric emptying in healthy subjects.

Water-induced hyperhydration increases total body water to a greater extent than glycerol-induced hyperhydration: a case study of a trained triathlete

Glycerol-induced hyperhydration (GIH) prior to endurance exercise is a strategy that is increasingly used by athletes. Compared with water-induced hyperhydration (WIH), GIH has been shown to reduce diuresis, thereby increasing total body water (TBW). It has never been demonstrated that WIH proved to be more efficient than GIH for increasing TBW. Therefore, we report the case of a trained triathlete in whom WIH, compared with GIH, increased TBW during a 110-min hydration protocol. On two separate days the subject ingested, in a randomized double blind fashion, either 26 ml.kg(-1) body mass (BM) of water or 26 ml.kg(-1) BM of water with 1.2 g glycerol.kg(-1) BM. Compared with GIH, WIH increased TBW by an additional 511 ml. It is proposed that WIH was effective in decreasing urine output and, therefore, in augmenting TBW, because the water ingested during this treatment was integrated into the body fluid pools relatively more slowly than that ingested during GIH. Practically, this finding implies that it could thus be possible for researchers and athletes to find out that on occasion WIH increases TBW more than GIH over a period of hydration of 2 h.

Intracisternal urocortin inhibits vagally stimulated gastric motility in rats: role of CRF(2)

1. Corticotropin-releasing factor (CRF) acts in the brain to inhibit thyrotropin-releasing hormone (TRH) analogue, RX-77368-induced vagal stimulation of gastric motility. We investigated CRF receptor-mediated actions of rat urocortin (rUcn) injected intracisternally (ic) on gastric motor function. 2. Urethane-anaesthetized rats with strain gauges on the gastric corpus were injected i.c. with rUcn and 20 min later, with i.c. RX-77368. CRF antagonists were injected i.c. 10 min before rUcn. 3. RX-77368 (1.5, 3, 10, 30 and 100 ng, i.c.) dose-dependently increased corpus contractions, expressed as total area under the curve (AUC, mV min(-1)) to 2.6+/-2.5, 6.1+/-5.9, 9.8+/-2.6, 69.7+/-21.7 and 74.9+/-28.7 respectively vs 0.2+/-0.1 after i.c. saline. Ucn (1, 3 or 10 microg) inhibited RX-77368 (30 ng)-induced increase in total AUC by 28, 62 and 93% respectively vs i.c. saline+RX-77368. 4. The CRF(1)/CRF(2) antagonist, astressin-B (60 microg, i.c.) completely blocked i.c. rUcn (3 microg, i.c.)-induced inhibition of gastric motility stimulated by RX-77368 (30 ng). 5. The selective CRF(2) antagonist, astressin(2)-B (30, 60 or 100 microg, i.c. ) dose-dependently prevented i.c. rUCn action while the CRF(1) antagonist, NBI-27914 did not. 6. In conscious rats, rUcn (0.6 or 1 microg, i.c.) inhibited gastric emptying of an ingested chow meal by 61 and 92% respectively. rUcn action was antagonized by astressin(2)-B. 7. These data show that i.c. rUcn acts through CRF(2) receptors to inhibit central vagal gastric contractile response and postoprandial emptying.

Microprocessor controlled movement of solid colonic content using sequential neural electrical stimulation

BACKGROUND AND AIMS

Invoked peristaltic contractions and movement of solid content have not been attempted in normal canine colon. The purpose of this study was to determine if movement of solid content through the colon could be produced by microprocessor controlled sequential stimulation.

METHODS

The study was performed on six anaesthetised dogs. At laparotomy, a 15 cm segment of descending colon was selected, the proximal end closed with a purse string suture, and the distal end opened into a collecting container. Four sets of subserosal stimulating electrodes were implanted at 3 cm intervals. The segment of bowel was filled with a mixture of dog food and 50 plastic pellets before each of 2-5 random sessions of non-stimulated or stimulated emptying. Propagated contractions were generated using microprocessor controlled bipolar trains of 50 Hz rectangular voltage having 20 V (peak to peak) amplitude, 18 second stimulus duration, and a nine second phase lag between stimulation trains in sequential electrode sets.

RESULTS

Electrical stimulation using the above mentioned parameters resulted in powerful phasic contractions that closed the lumen. By phase locking the stimulation voltage between adjacent sets of electrodes, propagated contractions could be produced in an aboral or orad direction. The number of evacuated pellets during the stimulation sessions was significantly higher than during the non-stimulated sessions (p<0.01).

CONCLUSIONS

Microprocessor controlled electrical stimulation accelerated movement of colonic content suggesting the possibility of future implantable colonic stimulators.

Cefaclor, a cephalosporin antibiotic, delays gastric emptying rate by a CCK-A receptor-mediated mechanism in the rat

Studies in vitro suggest that cephalosporin antibiotics release the gut hormone cholecystokinin. Cholecystokinin is known to inhibit gastric emptying. Here we examine the effects of cefaclor on gastric emptying and intestinal motility. Male Sprague-Dawley rats were fitted with gastric cannulas. Following a 3-week recovery, the rate of gastric emptying of saline, peptone (4.5%) or cefaclor was determined after instillation into the gastric cannula, while intestinal transit was measured by using the propagation of arabic gum + charcoal mixture given intraduodenally. Gastric emptying of saline was significantly delayed by the addition of cefaclor (3, 10, 30 or 100 mM). The CCK-A antagonist SR-27897B (1 mg kg(-1), i.p.) reversed the delay induced by 10 mM cefaclor, whereas the CCK-B antagonist CI-988 (1 mg kg(-1), i.p.) had no significant effect. In capsaicin-treated rats, 10 mM cefaclor emptied more rapidly than in vehicle-treated animals. Thirty-minute intestinal transit was increased at 30 and 100 mM of cefaclor, while the gastric acid secretion following cefaclor instillation was no different than the group which received saline. The cephalosporin antibiotic cefaclor appears to be a potent stimulant of CCK release from gut endocrine cells, resembling the effects of peptone. Cefaclor delays gastric emptying via capsaicin-sensitive afferent pathways, which involve CCK-A receptor interaction.

A comparison between Zhishi Xiaopiwan and cisapride in treatment of functional dyspepsia

AIM: To compare the therapeutic effect of the herbal medicine Zhishi Xiaopi with that of Cisapride in the treatment of functional dyspepsia (FD).

METHODS: Fifty-one FD patients were randomized into Herbal group (n = 27) and Cisapride group (n = 24). Two two groups were given a four-week treatment of Zhishi Xiaopiwan 100 mL, tid, a.c. and Cisapride 5 mg, tid, a.c. respectively. Patients’ symptoms were assessed and 39 patients’ (22 of Herbal group and 17 of Cisapride group) gastric liquid emptying times were measured with ultrasonography before and after the treatment.

RESULTS: The therapeutic effective rates of Herbal group and Cisapride group were 81.49% and 87.50% (P > 0.05). The half gastric emptying time (GET₅₀) and gastric emptying time (GET) of healthy controls and FD patients were 36.12 min ± 10.22 min vs 52.95 min ± 13.49 min and 87.07 min ± 21.11 min vs 120.74 min ± 23.08 min (P < 0.001). The GET50 and GET of Herbal group before and after the treatment were 51.63 min ± 13.15 min vs 45.62 min ± 10.82 min and 117.34 min ± 23.29 min vs 103.26 min ± 22.19 min (P < 0.01). The results of Cisapride group were 54.66 min ± 14.14 min vs 40.95 min ± 11.29 min and 125.12 min ± 24.47 min vs 95.49 min ± 22.31 min (P < 0.01). The differences in values (median) of GET₅₀ and GET for Herbal group and Cisapride group before and after treatment were 5.75 min vs 17.18 min and 13.22 min vs 33.54 min (P < 0.05).

CONCLUSION: Delayed gastric emptying is one of the pathogenesis of FD. Both Zhishi Xiaopi pills and Cisapride can effectively alleviate the symptoms of FD and accelerate gastric liquid emptying. The effect of Zhishi Xiaopiwan on enhancing gastric motility is comparable with but less than that of Cisapride.

Gastric electrical stimulation in patients with gastroparesis

As in the heart, there is a pacemaker in the human stomach and it generates myoelectrical activity with a frequency of approximately three cycles per minute. Abnormalities in gastric myoelectrical activity may result in gastric motility disorders, such as gastroparesis. Electrical stimulation of the stomach is achieved by delivering electrical currents via electrodes attached to the smooth muscle of the stomach. Recently, a number of studies on electrical stimulation of the stomach in both humans and dogs have indicated that gastric electrical stimulation with appropriate parameters is able to entrain gastric slow waves and normalize gastric dysrhythmias. This has led some investigators to use gastric electrical stimulation to treat patients with gastroparesis. Previous studies and the current state of the field in gastric electrical stimulation in treatment of gastroparesis will be discussed and summarized.

Inhibition of gastric emptying and intestinal transit by amphetamine through a mechanism involving an increased secretion of CCK in male rats

1. The effect of amphetamine on gastrointestinal (GI) transit and the plasma levels of cholecystokinin (CCK) were studied in male rats. 2. Gastric emptying was inhibited both acutely and chronically by the administration of amphetamine. GI transit was decreased by the acute administration of amphetamine but not affected by the chronic administration of amphetamine. 3. Plasma CCK levels were increased dose-dependently by amphetamine. 4. Proglumide, a CCK receptor antagonist, prevented amphetamine-induced inhibition of gastric emptying and the decrease in GI transit in male rats. 5. The selective CCK(A) receptor antagonist, lorglumide, dose-dependently attenuated the amphetamine-induced inhibition of gastric emptying in male rats. In contrast, the selective CCK(B) receptor antagonist, PD 135,158, did not reverse the effect of amphetamine on gastric emptying. 6. Both lorglumide and PD 135,158 reversed the inhibitory effect of amphetamine on GI transit in male rats. 7. These results suggest that amphetamine-induced inhibition of gastric emptying and intestinal transit is due in part to a mechanism associated with the hypersecretion of endogenous CCK.

Effects of levosulpiride in patients with functional dyspepsia accompanied by delayed gastric emptying

OBJECTIVES

Levosulpiride is the levo-enantiomer of sulpiride, a well-known antiemetic, antidyspeptic and antipsychotic drug. This study was undertaken to investigate the effects of levosulpiride on dyspeptic symptoms and gastric motor function in a group of patients with functional dyspepsia showing delayed gastric emptying.

METHOD

Forty two eligible patients were entered into a 3 week, double-blind randomized comparison of 25mg of levosulpiride or placebo t.i.d.. Symptom assessment and gastric scintigraphy following the intake of scrambled egg sandwich, were performed in each patient before and after treatment.

RESULTS

The improvement of symptom score in levosulpiride group was higher than the placebo group (p < 0.05). We assessed global efficacy, which was excellent in 1 (6%), good 11 (65%), fair 4 (24%), nil 1 (6%) of those receiving levosulpiride, and fair 9 (60%), nil 5 (33%), poor 1 (6%) of those receiving placebo. Levosulpiride tended to be more effective than placebo in relieving the dyspeptic symptoms especially in the subgroups of dysmotility-like (p < 0.05) and nonspecific (p < 0.05) as compared to other subgroups (p = 0.16). The reduction of gastric emptying time after levosulpiride treatment was more marked than Placebo group (p < 0.05). We found a significant correlation between changes of symptom score and gastric emptying time (r = 0.47, p = 0.01). No serious adverse effects were reported after administration of either levosulpiride or placebo. Only two patients reported mild somnolence during levosulpiride administration.

CONCLUSIONS

Levosulpiride is effective and well tolerated in patients with functional dyspepsia accompanied by delayed gastric emptying. Its efficacy may be related to its action on the gastric motor function by improving the delayed gastric emptying.