Gallbladder contraction, gastric emptying and antral motility: Single visit assessment of upper GI function in untreated celiac disease using echo-planar MRI

The Introduction of a New Flexible In Vivo Predictive Dissolution Apparatus, GIS-Alpha (GIS-α), to Study Dissolution Profiles of BCS Class IIb Drugs, Dipyridamole and Ketoconazole

The physiological pH changes and peristalsis activities in gastrointestinal (GI) tract have big impact on the dissolution of oral drug products, when those oral drug products include APIs with pH-dependent solubility. It is well documented that predicting the bioperformance of those oral drug products can be challenging using compendial methods. To overcome this limitation, in vivo predictive dissolution apparatuses, such as the transfer model, have been developed to predict bioperformance of oral formulation candidates and drug products. In this manuscript we utilize a new transfer-model dissolution apparatus, the gastrointestinal simulator-α (GIS-α), to characterize its behavior in terms of transfer kinetics and pH, assess its reproducibility and adaptability to mimic different transfer conditions, as well as study dissolution of ketoconazole and dipyridamole as model BCS class IIb compounds. Availability of commercially available dissolution transfer systems with similar configuration to compendial dissolution apparatus, may be helpful to simplify and standardize in vivo predictive dissolution methodologies for BCS class IIb compounds in the future.

Effects of a Gluten-Containing Meal on Gastric Emptying and Gallbladder Contraction

The ingestion of gluten has been associated with gastrointestinal symptoms even in the absence of detectable immune responses. Little is known about the pathophysiological effects of gluten on the upper gastrointestinal tract. We aimed to assess whether the ingestion of gluten leads to an impairment of the physiological mechanisms of gastric emptying, gallbladder contraction and relaxation. A total of 17 healthy subjects underwent ultrasound evaluation of gastric emptying dynamics and gallbladder contractions at baseline and every 30 min after a standard gluten-containing and gluten-free meal (250 kcal, 70% carbohydrates). The pattern of gastric emptying was similar after a standard meal with or without gluten, but differed in terms of the peak of the antral filling curve, which was wider (mean area 5.69, median 4.70, range 3.71‒9.27 cm² vs. mean 4.89, median 4.57, 2.27‒10.22 cm², p = 0.023) after the gluten-containing meal. The pattern of gallbladder contractions was different after the gluten-free meal (p < 0.05), with higher gallbladder volumes in the late refilling phases. The results of this study show that gluten ingestion exerts objective effects on gastric and gallbladder motility. Although the underlying pathophysiological mechanism remains unknown, these results could account for some of the gluten-related symptoms reported by patients with celiac disease and non-celiac gluten sensitivity.

Impact of gastric pH profiles on the proteolytic digestion of mixed βlg-Xanthan biopolymer gels

Gastric pH profile duringin vitrogastric digestion is critical for proper assessment of mixed biopolymer gel proteolysis.

Measurement of gastric meal and secretion volumes using magnetic resonance imaging

MRI can assess multiple gastric functions without ionizing radiation. However, time consuming image acquisition and analysis of gastric volume data, plus confounding of gastric emptying measurements by gastric secretions mixed with the test meal have limited its use to research centres. This study presents an MRI acquisition protocol and analysis algorithm suitable for the clinical measurement of gastric volume and secretion volume. Reproducibility of gastric volume measurements was assessed using data from 10 healthy volunteers following a liquid test meal with rapid MRI acquisition within one breath-hold and semi-automated analysis. Dilution of the ingested meal with gastric secretion was estimated using a respiratory-triggered T1 mapping protocol. Accuracy of the secretion volume measurements was assessed using data from 24 healthy volunteers following a mixed (liquid/solid) test meal with MRI meal volumes compared to data acquired using gamma scintigraphy (GS) on the same subjects studied on a separate study day. The mean ± SD coefficient of variance between 3 observers for both total gastric contents (including meal, secretions and air) and just the gastric contents (meal and secretion only) was 3  ±  2% at large gastric volumes (>200 ml). Mean ± SD secretion volumes post meal ingestion were 64  ±  51 ml and 110  ±  40 ml at 15 and 75 min, respectively. Comparison with GS meal volumes, showed that MRI meal only volume (after correction for secretion volume) were similar to GS, with a linear regression gradient ± std err of 1.06  ±  0.10 and intercept -11  ±  24 ml. In conclusion, (i) rapid volume acquisition and respiratory triggered T₁ mapping removed the requirement to image during prolonged breath-holds (ii) semi-automatic analysis greatly reduced the time required to derive measurements and (iii) correction for secretion volumes provided accurate assessment of gastric meal volumes and emptying. Together these features provide the scientific basis of a protocol which would be suitable in clinical practice.

Effects of various food ingredients on gall bladder emptying

Background/objectives:

The emptying of the gall bladder in response to feeding is pivotal for the digestion of fat, but the role of various food ingredients in contracting the gall bladder postprandially is not well understood. We hypothesized that different food ingredients, when consumed, will have a different effect on stimulating gall bladder emptying. To investigate this we designed two randomized, investigator-blind, cross-over studies in healthy subjects using magnetic resonance imaging (MRI) to measure gall bladder volumes serially and non-invasively.

Subjects/methods:

Study 1: exploratory study evaluating the effects of 10 different food ingredients on gall bladder emptying in eight healthy subjects. The choice of ingredients varied from common items like coffee, tea and milk to actives like curcumin and potato protease inhibitor. Study 2: mechanistic study investigating the cholecystokinin (CCK) dose response to the best performer ingredient from Study 1 in 21 healthy subjects four ways.

Results:

The largest gall bladder volume change in Study 1 was observed with fat, which therefore became the dose-response ingredient in Study 2, where the maximum % gall bladder volume change correlated well with CCK.

Conclusions:

These serial test-retest studies showed that the fasted gall bladder volume varied remarkably between individuals and that individual day-to-day variability had wide coefficients of variation. Improved knowledge of how to stimulate bile release using food ingredients will be useful to improve in vitro–in vivo correlation of bioavailability testing of hydrophobic drugs. It could improve performance of cholesterol-lowering plant stanol and sterol products and possibly aid understanding of some cholesterol gallstone disease.

Assessment of gastrointestinal motor functions by MRI: a comprehensive review

BACKGROUND

Magnetic resonance imaging (MRI) is a useful technique for evaluating gastrointestinal (GI) motor functions because it provides multi-planar imaging capability, high imaging speed, good spatial resolution and excellent soft tissue contrast. Moreover, multiple parameters of GI function can be assessed non-invasively during a single study.

PURPOSE

This critical review of the literature discusses the strengths and limitations of MRI for evaluating GI motor functions.

Effects of a 5-HT(3) antagonist, ondansetron, on fasting and postprandial small bowel water content assessed by magnetic resonance imaging

BACKGROUND

5-HT(3) antagonists have been shown to be effective in relieving the symptoms of irritable bowel syndrome with diarrhoea (IBS-D). Using a recently validated magnetic resonance imaging (MRI) method, we have demonstrated reduced fasting small bowel water content (SBWC) in IBS-D associated with accelerated small bowel transit. We hypothesized that slowing of transit with ondansetron would lead to an increase in SBWC by inhibiting fasting motility.

AIM

To assess the effects of ondansetron compared with placebo in healthy volunteers on SBWC and motility in two different groups of subjects, one studied using MRI and another using manometry.

METHODS

Healthy volunteers were given either a placebo or ondansetron on the day prior to and on the study day. Sixteen volunteers underwent baseline fasting and postprandial MRI scans for 270 min. In a second study, a separate group of n = 18 volunteers were intubated and overnight migrating motor complex (MMC) recorded. Baseline MRI scans were carried out after the tube was removed.

RESULTS

Fasting SBWC was markedly increased by ondansetron (P < 0.0007). Ondansetron reduced the overall antroduodenal Motility Index (P < 0.04). The subjects who were intubated had significantly lower fasting SBWC (P < 0.0002) compared with the group of subjects who were not intubated.

CONCLUSIONS

The 5-HT(3) receptor antagonism increased fasting small bowel water. This was associated with reduced fasting antroduodenal Motility Index which may explain the clinical benefit of such drugs.

Magnetic resonance imaging in the evaluation of the gastric emptying and antral motion: feasibility and reproducibility of a fast not invasive technique

PURPOSE

The aim of this study was to evaluate reproducibility of a fast MRI protocol to measure gastric emptying and motility of the gastric antrum.

METHODS AND MATERIALS

Gastric emptying and antral speed were measured in 12 type 1 diabetic patients (mean age 43 years) and 9 healthy volunteers (mean age 31 years). Subjects, fasting from 6h, were evaluated in supine position using a 1.5T MR scanner and a eight-channels phased-array body coil after ingestion of 400 ml of a vanillas pudding mixed with 5 ml of Gd-DTPA. Axial 3D T1w sequence at 0 and 30 min for volume evaluation and cine-steady state acquisition every 5 min for a total time of 30 min for gastric wave speed assessing were acquired. Two blinded observers extrapolated T(1/2) from gastric volume assessment and speed of gastric waves.

RESULTS

All the patients tolerated the examination. The T(1/2) cut-off was of 115 min with an accuracy in differentiate controls from diabetics of 96% (95% CI 0.766-0.992; p<0.001), while the antral speed cut-off was of 0.15 mm/s with an accuracy of 87% (95% CI 0.628-0.977; p<0.001). The inter-observer agreement for the volumes at time 0 and 30 min was respectively 0.983 (95% CI 0.9628-0.9929; p<0.001) and 0.9933 (95% CI 0.9847-0.9971; p<0.001) with an agreement of 0.9918 (95% CI 0.9853-0.9954; p<0.001), while for antral speed it was of 0.935 (95% CI 0.9097-0.9528; p<0.001).

CONCLUSIONS

MRI is a reproducible technique for the evaluation of gastric emptying and antral motility.

Coordinate regulation of gallbladder motor function in the gut-liver axis

Gallstones are one of the most common digestive diseases with an estimated prevalence of 10%-15% in adults living in the western world, where cholesterol-enriched gallstones represent 75%-80% of all gallstones. In cholesterol gallstone disease, the gallbladder becomes the target organ of a complex metabolic disease. Indeed, a fine coordinated hepatobiliary and gastrointestinal function, including gallbladder motility in the fasting and postprandial state, is of crucial importance to prevent crystallization and precipitation of excess cholesterol in gallbladder bile. Also, gallbladder itself plays a physiopathological role in biliary lipid absorption. Here, we present a comprehensive view on the regulation of gallbladder motor function by focusing on recent discoveries in animal and human studies, and we discuss the role of the gallbladder in the pathogenesis of gallstone formation.

Lack of correlation of degree of villous atrophy with severity of clinical presentation of coeliac disease

BACKGROUND AND AIM

Both the clinical presentation and the degree of mucosal damage in coeliac disease vary greatly. In view of conflicting information as to whether the mode of presentation correlates with the degree of villous atrophy, we reviewed a large cohort of patients with coeliac disease.

PATIENTS AND METHODS

We correlated mode of presentation (classical, diarrhoea predominant or atypical/silent) with histology of duodenal biopsies and examined their trends over time.

RESULTS

The cohort consisted of 499 adults, mean age 44.1 years, 68% females. The majority had silent coeliac disease (56%) and total villous atrophy (65%). There was no correlation of mode of presentation with the degree of villous atrophy (p=0.25). Sixty-eight percent of females and 58% of males had a severe villous atrophy (p=0.052). There was a significant trend over time for a greater proportion of patients presenting as atypical/silent coeliac disease and having partial villous atrophy, though the majority still had total villous atrophy.

CONCLUSIONS

Among our patients the degree of villous atrophy in duodenal biopsies did not correlate with the mode of presentation, indicating that factors other than the degree of villous atrophy must account for diarrhoea in coeliac disease.

Gallstone disease: Symptoms and diagnosis of gallbladder stones

The clinical aspects and the diagnostic features of gallstone disease are described. The natural history of silent gallstones is overviewed, and the risk of developing symptoms and complications is also discussed. The importance of colicky pain as a specific gallstone symptom is highlighted, and the role of both laboratory tests and diagnostic investigations for differential diagnosis is discussed. Finally, we describe the diagnostic features of gallbladder stone disease, including indications, sensitivity, specificity, and limitations of different test investigations under special circumstances.