Evaluation of gut motility in type II diabetes by the radiopaque marker method

Development of a Physiologically Based Pharmacokinetic Population Model for Diabetic Patients and its Application to Understand Disease-drug-drug Interactions

INTRODUCTION

The activity changes of cytochrome P450 (CYP450) enzymes, along with the complicated medication scenarios in diabetes mellitus (DM) patients, result in the unanticipated pharmacokinetics (PK), pharmacodynamics (PD), and drug-drug interactions (DDIs). Physiologically based pharmacokinetic (PBPK) modeling has been a useful tool for assessing the influence of disease status on CYP enzymes and the resulting DDIs. This work aims to develop a novel diabetic PBPK population model to facilitate the prediction of PK and DDI in DM patients.

METHODS

First, mathematical functions were constructed to describe the demographic and non-CYP physiological characteristics specific to DM, which were then incorporated into the PBPK model to quantify the net changes in CYP enzyme activities by comparing the PK of CYP probe drugs in DM versus non-DM subjects.

RESULTS

The results show that the enzyme activity is reduced by 32.3% for CYP3A4/5, 39.1% for CYP2C19, and 27% for CYP2B6, while CYP2C9 activity is enhanced by 38% under DM condition. Finally, the diabetic PBPK model was developed through integrating the DM-specific CYP activities and other parameters and was further used to perform PK simulations under 12 drug combination scenarios, among which 3 combinations were predicted to result in significant PK changes in DM, which may cause DDI risks in DM patients.

CONCLUSIONS

The PBPK modeling applied herein provides a quantitative tool to assess the impact of disease factors on relevant enzyme pathways and potential disease-drug-drug-interactions (DDDIs), which may be useful for dosing regimen optimization and minimizing the DDI risks associated with the treatment of DM.

Simultaneously Predicting the Pharmacokinetics of CES1-Metabolized Drugs and Their Metabolites Using Physiologically Based Pharmacokinetic Model in Cirrhosis Subjects

Hepatic carboxylesterase 1 (CES1) metabolizes numerous prodrugs into active ingredients or direct-acting drugs into inactive metabolites. We aimed to develop a semi-physiologically based pharmacokinetic (semi-PBPK) model to simultaneously predict the pharmacokinetics of CES1 substrates and their active metabolites in liver cirrhosis (LC) patients. Six prodrugs (enalapril, benazepril, cilazapril, temocapril, perindopril and oseltamivir) and three direct-acting drugs (flumazenil, pethidine and remimazolam) were selected. Parameters such as organ blood flows, plasma-binding protein concentrations, functional liver volume, hepatic enzymatic activity, glomerular filtration rate (GFR) and gastrointestinal transit rate were integrated into the simulation. The pharmacokinetic profiles of these drugs and their active metabolites were simulated for 1000 virtual individuals. The developed semi-PBPK model, after validation in healthy individuals, was extrapolated to LC patients. Most of the observations fell within the 5th and 95th percentiles of simulations from 1000 virtual patients. The estimated AUC and Cmax were within 0.5-2-fold of the observed values. The sensitivity analysis showed that the decreased plasma exposure of active metabolites due to the decreased CES1 was partly attenuated by the decreased GFR. Conclusion: The developed PBPK model successfully predicted the pharmacokinetics of CES1 substrates and their metabolites in healthy individuals and LC patients, facilitating tailored dosing of CES1 substrates in LC patients.

Pan-alimentary assessment of motility, luminal content, and structures: an MRI-based framework

BACKGROUND

Gastrointestinal symptoms originating from different segments overlap and complicate diagnosis and treatment. In this study, we aimed to develop and test a pan-alimentary framework for the evaluation of gastrointestinal (GI) motility and different static endpoints based on magnetic resonance imaging (MRI) without contrast agents or bowel preparation.

METHODS

Twenty healthy volunteers (55.6 ± 10.9 years, BMI 30.8 ± 9.2 kg/m2) underwent baseline and post-meal MRI scans at multiple time points. From the scans, the following were obtained: Gastric segmental volumes and motility, emptying half time (T50), small bowel volume and motility, colonic segmental volumes, and fecal water content. Questionnaires to assess GI symptoms were collected between and after MRI scans.

KEY RESULTS

We observed an increase in stomach and small bowel volume immediately after meal intake from baseline values (p<.001 for the stomach and p=.05 for the small bowel). The volume increase of the stomach primarily involved the fundus (p<.001) in the earliest phase of digestion with a T50 of 92.1 ± 35.3 min. The intake of the meal immediately elicited a motility increase in the small bowel (p<.001). No differences in colonic fecal water content between baseline and 105 min were observed.

CONCLUSION & INFERENCES

We developed a framework for a pan-alimentary assessment of GI endpoints and observed how different dynamic and static physiological endpoints responded to meal intake. All endpoints aligned with the current literature for individual gut segments, showing that a comprehensive model may unravel complex and incoherent gastrointestinal symptoms in patients.

Novel insights into the pathogenic impact of diabetes on the gastrointestinal tract

Type 2 and type 1 diabetes are common endocrine disorders with a progressively increasing incidence worldwide. These chronic, systemic diseases have multiorgan implications, and the whole gastrointestinal (GI) tract represents a frequent target in terms of symptom appearance and interdependent pathophysiological mechanisms. Metabolic alterations linked with diabetic complications, neuropathy and disrupted hormone homeostasis can lead to upper and/or lower GI symptoms in up to 75% of diabetic patients, with multifactorial involvement of the oesophagus, stomach, upper and lower intestine, and of the gallbladder. On the other hand, altered gastrointestinal motility and/or secretions are able to affect glucose and lipid homeostasis in the short and long term. Finally, diabetes has been linked with increased cancer risk at different levels of the GI tract. The presence of GI symptoms and a comprehensive assessment of GI function should be carefully considered in the management of diabetic patients to avoid further complications and to ameliorate the quality of life. Additionally, the presence of gastrointestinal dysfunction should be adequately managed to improve metabolic homeostasis, the efficacy of antidiabetic treatments and secondary prevention strategies.

Physiologically-Based Pharmacokinetic-Pharmacodynamics Model Characterizing CYP2C19 Polymorphisms to Predict Clopidogrel Pharmacokinetics and Its Anti-Platelet Aggregation Effect Following Oral Administration to Coronary Artery Disease Patients With or Without Diabetes

Background and Objective: Clopidogrel (CLOP) is commonly used in coronary artery disease (CAD) patients with or without diabetes (DM), but these patients often suffer CLOP resistance, especially those with diabetes. This study was aimed to develop a physiologically-based pharmacokinetic-pharmacodynamic (PBPK-PD) model to describe the pharmacokinetics and pharmacodynamics of clopidogrel active metabolite (CLOP-AM) in CAD patients with or without DM.

Methods: The PBPK-PD model was first established and validated in healthy subjects and then in CAD patients with or without DM. The influences of CYP2C19, CYP2C9, CYP3A4, carboxylesterase 1 (CES1), gastrointestinal transit rates (K_t,i) and platelets response to CLOP-AM (k_irre) on predicted pharmacokinetics and pharmacodynamics were investigated, followed with their individual and integrated effects on CLOP-AM pharmacokinetics due to changes in DM status.

Results: Most predictions fell within 0.5–2.0 folds of observations, indicating successful predictions. Sensitivity analysis showed that contributions of interested factors to pharmacodynamics were CES1> k_irre> K_t,i> CYP2C19 > CYP3A4> CYP2C9. Mimicked analysis showed that the decreased exposure of CLOP-AM by DM was mainly attributed to increased CES1 activity, followed by decreased CYP2C19 activity.

Conclusion: The pharmacokinetics and pharmacodynamics of CLOP-AM were successfully predicted using the developed PBPK-PD model. Clopidogrel resistance by DM was the integrated effects of altered K_t,i, CYP2C19, CYP3A4, CES1 and k_irre.

Population pharmacokinetics of gabapentin in patients with neuropathic pain: Lack of effect of diabetes or glycaemic control

AIMS

Gabapentin (GBP) is widely used to treat neuropathic pain, including diabetic neuropathic pain. Our objective was to evaluate the role of diabetes and glycaemic control on GBP population pharmacokinetics.

METHODS

A clinical trial was conducted in patients with neuropathic pain (n = 29) due to type 2 diabetes (n = 19) or lumbar/cervical disc herniation (n = 10). All participants were treated with a single oral dose GBP. Blood was sampled up to 24 hours after GBP administration. Data were analysed with a population approach using the stochastic approximation expectation maximization algorithm. Weight, body mass index, sex, biomarkers of renal function and diabetes, and genotypes for the main genetic polymorphisms of SLC22A2 (rs316019) and SLC22A4 (rs1050152), the genes encoding the transporters for organic cations OCT2 and OCTN1, were tested as potential covariates.

RESULTS

GBP drug disposition was described by a 1-compartment model with lag-time, first-order absorption and linear elimination. The total clearance was dependent on estimated glomerular filtration rate. Population estimates (between-subject variability in percentage) for lag time, first-order absorption rate, apparent volume of distribution and total clearance were 0.316 h (10.6%), 1.12 h^-1 (10.7%), 140 L (7.7%) and 14.7 L/h (6.97%), respectively. No significant association was observed with hyperglycaemia, glycated haemoglobin, diabetes diagnosis, age, sex, weight, body mass index, SLC22A2 or SLC22A4 genotypes.

CONCLUSION

This population pharmacokinetics model accurately estimated GBP concentrations in patients with neuropathic pain, using estimated glomerular filtrationrate as a covariate for total clearance. The distribution and excretion processes of GBP were not affected by hyperglycaemia or diabetes.

Effect of Tailored Perigastric Lymph Node Dissection on Gastric Motility in a Canine Model

BACKGROUND

Combination laparoscopic lymph node (LN) dissection and endoscopic resection is a promising treatment for early gastric cancer. However, LN dissection could cause nerve injury and deterioration of motility in the preserved stomach. This experimental study aims to evaluate changes in gastric motility after tailored perigastric regional lymph node dissection without gastrectomy.

MATERIALS AND METHODS

We identified four most frequently involved LN combinations considering tumor location from retrospective reviews of 4697 gastrectomy patients. We randomly assigned 55 dogs to five groups: control (laparotomy only) and four experimental groups with LN dissection without gastrectomy: group 1 (LNs 3, 7, and 8), group 2 (LNs 3, 4, and 6), group 3 (LNs 1, 3, and 7), and group 4 (LNs 3, 4, and 11). Gastric emptying time (GET) was measured using barium-impregnated polyethylene spheres. GET₅₀ and GET₇₅ were the time points when 50% and 75% of the markers, respectively, had emptied from the stomach.

RESULTS

On postoperative days (PODs) 2 and 3, GET_50, GET_75, and proportion of GET₅₀ <4 h in groups 1 and 2 were comparable with controls. However, group 3 showed delayed GET₅₀ and GET₇₅, and groups 3 and 4 demonstrated significantly smaller proportions of GET₅₀ <4 h compared with controls on PODs 2 and 3. This effect resolved by POD 6 and there were no significant differences in GET_50, GET_75, or proportion of GET₅₀ <4 h between the groups.

CONCLUSIONS

Tailored perigastric LN resection without gastrectomy was feasible and acceptable in terms of postoperative motility in the preserved stomach.

Interdependency between mechanical parameters and afferent nerve discharge in remodeled diabetic Goto-Kakizaki rat intestine

Background

Gastrointestinal disorders are very common in diabetic patients, but the pathogenesis is still not well understood. Peripheral afferent nerves may be involved due to the complex regulation of gastrointestinal function by the enteric nervous system.

Objective

We aimed to characterize the stimulus–response function of afferent fibers innervating the jejunum in the Goto-Kakizaki (GK) type 2 diabetic rat model. A key question is whether changes in afferent firing arise from remodeled tissue or from adaptive afferent processes.

Design

Seven 32-week-old male GK rats and seven age-matched normal Wistar rats were studied. Firing from mesenteric afferent nerves was recorded in excised jejunal segments of seven GK rats and seven normal Wistar rats during ramp test, stress relaxation test, and creep test. The circumferential stress–strain, spike rate increase ratio (SRIR), and single unit firing rates were calculated for evaluation of interdependency of the mechanical stimulations and the afferent nerve discharge.

Results

Elevated sensitivity to mechanical stimuli was found for diabetic nerve bundles and single unit activity (P<0.05). The stress relaxed less in the diabetic intestinal segment (P<0.05). Linear association between SRIR and the thickness of circumferential muscle layer was found at high stress levels as well as for SRIR and the glucose level.

Conclusion

Altered viscoelastic properties and elevated mechanosensitivity were found in the GK rat intestine. The altered nerve signaling is related to muscle layer remodeling and glucose levels and may contribute to gastrointestinal symptoms experienced by diabetic patients.

Role of wireless motility capsule in the assessment and management of gastrointestinal dysmotility in patients with diabetes mellitus

BACKGROUND

Gastrointestinal (GI) dysmotility is common in diabetic patients. Wireless Motility Capsule (WMC) provides the transit profile of the entire GI tract in a single study. Factors affecting GI dysmotility and utility of WMC study are not clearly established in diabetic patients. Our aims were to study the pattern of GI dysmotility using WMC and evaluate the effect of glycemic control and presence of diabetic microvascular complications on motility impairment in diabetic patients. We also assessed the impact of WMC findings on clinical management.

METHODS

Retrospective chart review of all diabetic patients who underwent WMC testing at our institution from 2010 to 2015 was performed. Demographics, hemoglobinA1c levels, microvascular complications, and WMC findings were obtained. Impact of WMC on clinical management was assessed.

KEY RESULTS

A total of 100 patients were included. Mean age was 45±19 years and 76% were female. Seventy-two percentage had abnormal WMC testing, of which 29 (40%) had multiregional dysmotility. There were no significant differences in demographics, diabetic microvascular complications or hemoglobinA1c levels among patients with normal and abnormal WMC testing or among patients with isolated vs multiregional dysmotility. Information about subsequent clinical management was available for 47 patients. WMC testing was abnormal in 33 (70%) patients and treatment changes based on WMC results were made in 24 patients (73%).

CONCLUSIONS & INFERENCES

There was no association between hemoglobinA1c levels, microvascular complications and pattern of GI dysmotility in diabetic patients undergoing WMC. WMC testing lead to management changes in approximately 75% of diabetic patients with GI dysmotility.

Diabetes-induced mechanophysiological changes in the small intestine and colon

The disorders of gastrointestinal (GI) tract including intestine and colon are common in the patients with diabetes mellitus (DM). DM induced intestinal and colonic structural and biomechanical remodeling in animals and humans. The remodeling is closely related to motor-sensory abnormalities of the intestine and colon which are associated with the symptoms frequently encountered in patients with DM such as diarrhea and constipation. In this review, firstly we review DM-induced histomorphological and biomechanical remodeling of intestine and colon. Secondly we review motor-sensory dysfunction and how they relate to intestinal and colonic abnormalities. Finally the clinical consequences of DM-induced changes in the intestine and colon including diarrhea, constipation, gut microbiota change and colon cancer are discussed. The final goal is to increase the understanding of DM-induced changes in the gut and the subsequent clinical consequences in order to provide the clinicians with a better understanding of the GI disorders in diabetic patients and facilitates treatments tailored to these patients.

Noninvasive Measurement of Transit Time in Short Bowel Syndrome

BACKGROUND

Patients with short bowel syndrome (SBS) have limited absorption of nutrients, in part because of the rapidity with which chyme passes through the bowel. We sought to evaluate noninvasive measurements of intestinal transit time to aid in research questions where transit is measured repeatedly.

METHODS

Three methods were compared in 8 patients with SBS: the time for blue food color to appear in ostomy effluent or stool, lactulose breath hydrogen testing, and the first radiopaque ring from a capsule in timed stool samples.

RESULTS

Median blue dye fasted transit was 96.3 minutes, with breakfast was 117.3 minutes, and with lactulose was 72 minutes. By breath hydrogen testing, transit time was 52.5 minutes but detectible in only 5 of 13 tests. Transit time by radiopaque marker was 967 minutes, but no markers passed in 7 of 14 tests.

CONCLUSIONS

Visualization of blue food color in ostomy effluent is a simple, inexpensive approach that can be applied to fasted subjects or after specific meals. Breath hydrogen testing should only be applied in the rare patient with SBS who has an intact ileocecal valve. Radiopaque markers are less useful, most likely because they become trapped due to anatomic changes.

Clinical pharmacology of daikenchuto assessed by transit analysis using radiopaque markers in patients with colon cancer undergoing open surgery: a multicenter double-blind randomized placebo-controlled study (JFMC39-0902 additional study)

BACKGROUND

This exploratory trial was conducted to investigate whether daikenchuto accelerates the recovery of gastrointestinal function in patients undergoing open surgery for sigmoid or rectosigmoid cancer.

METHODS

Eighty-eight patients who underwent colectomy at one of the 11 clinical trial sites in Japan from January 2009 to June 2011 were registered in the study. Patients received either placebo or daikenchuto (15.0 g/day, 5 g three times a day) from postoperative day 2 to postoperative day 8. The study end points included the gastrointestinal tract transit time evaluated with radiopaque markers and the time to first flatus. The safety profile of daikenchuto was also evaluated until postoperative day 8.

RESULTS

Seventy-one patients (daikenchuto, n = 38; placebo, n = 33) were statistically analyzed. Although the number of radiopaque markers in the anal side of the small intestine at 6 h was significantly greater in the daikenchuto group than in the placebo group (15.19 vs 10.06, p = 0.008), the total transit analysis results and the mean time to first flatus did not differ significantly between the two groups.

CONCLUSIONS

Daikenchuto has a positive effect on the resolution of delayed gastric emptying, but has a limited effect on the resolution of postoperative paralytic ileus after open surgery in patients with sigmoid or rectosigmoid cancer. Daikenchuto may contribute to early oral intake in the postoperative course.

Role of epidural and patient-controlled analgesia in site-specific laparoscopic colorectal surgery

Background and Objectives:

Limited data are available comparing epidural and patient-controlled analgesia in site-specific colorectal surgery. The aim of this study was to evaluate 2 modes of analgesia in patients undergoing laparoscopic right colectomy (RC) and low anterior resection (LAR).

Methods:

Prospectively collected data on 433 patients undergoing laparoscopic or laparoscopic-assisted colon surgery at a single institution were retrospectively reviewed from March 2004 to February 2009. Patients were divided into groups undergoing RC (n = 175) and LAR (n = 258). These groups were evaluated by use of analgesia: epidural analgesia, “patient-controlled analgesia” alone, and a combination of both. Demographic and perioperative outcomes were compared.

Results:

Epidural analgesia was associated with a faster return of bowel function, by 1 day (P < .001), in patients who underwent LAR but not in the RC group. Delayed return of bowel function was associated with increased operative time in the LAR group (P = .05), patients with diabetes who underwent RC (P = .037), and patients after RC with combined analgesia (P = .011). Mean visual analogue scale pain scores were significantly lower with epidural analgesia compared with patient-controlled analgesia in both LAR and RC groups (P < .001).

Conclusion:

Epidural analgesia was associated with a faster return of bowel function in the laparoscopic LAR group but not the RC group. Epidural analgesia was superior to patient-controlled analgesia in controlling postoperative pain but was inadequate in 28% of patients and needed the addition of patient-controlled analgesia.

Blunting of Colon Contractions in Diabetics with Gastroparesis Quantified by Wireless Motility Capsule Methods

Generalized gut transit abnormalities are observed in some diabetics with gastroparesis. Relations of gastric emptying abnormalities to colon contractile dysfunction are poorly characterized. We measured colon transit and contractility using wireless motility capsules (WMC) in 41 healthy subjects, 12 diabetics with gastroparesis (defined by gastric retention >5 hours), and 8 diabetics with normal gastric emptying (≤5 hours). Overall numbers of colon contractions >25 mmHg were calculated in all subjects and were correlated with gastric emptying times for diabetics with gastroparesis. Colon transit periods were divided into quartiles by time and contraction numbers were calculated for each quartile to estimate regional colon contractility. Colon transit in diabetics with gastroparesis was prolonged vs. healthy subjects (P<0.0001). Overall numbers of colon contractions in gastroparetics were lower than controls (P = 0.02). Diabetics with normal emptying showed transit and contraction numbers similar to controls. Gastric emptying inversely correlated with overall contraction numbers in gastroparetics (r = -0.49). Numbers of contractions increased from the 1^st to 4^th colon transit quartile in controls and diabetics with normal emptying (P≤0.04), but not gastroparetics. Numbers of contractions in the 3^rd and 4^th quartiles were reduced in gastroparetics vs. healthy controls (P≤0.05) and in the 4^th quartile vs. diabetics with normal emptying (P = 0.02). Numbers of contractions were greatest in the final 15 minutes of transit, but were reduced in gastroparetics vs. healthy controls and diabetics with normal emptying (P≤0.005). On multivariate analyses, differences in numbers of contractions were not explained by demographic or clinical variables. In conclusion, diabetics with gastroparesis exhibit delayed colon transit associated with reductions in contractions that are prominently blunted in latter transit phases and which correlate with delayed gastric emptying, while diabetics with normal emptying show no significant colonic impairments. These findings emphasize diabetic gastroparesis may be part of a generalized dysmotility syndrome.

Prediction of drug disposition in diabetic patients by means of a physiologically based pharmacokinetic model

BACKGROUND AND OBJECTIVE

Accumulating evidence has shown that diabetes mellitus may affect the pharmacokinetics of some drugs, leading to alteration of pharmacodynamics and/or toxic effects. The aim of this study was to develop a novel physiologically based pharmacokinetic (PBPK) model for predicting drug pharmacokinetics in patients with type 2 diabetes mellitus quantitatively.

METHODS

Contributions of diabetes-induced alteration of physiological parameters including gastric emptying rates, intestinal transit time, drug metabolism in liver and kidney functions were incorporated into the model. Plasma concentration-time profiles and pharmacokinetic parameters of seven drugs (antipyrine, nisoldipine, repaglinide, glibenclamide, glimepiride, chlorzoxazone, and metformin) in non-diabetic and diabetic patients were predicted using the developed model. The PBPK model coupled with a Monte-Carlo simulation was also used to predict the means and variability of pharmacokinetic parameters.

RESULTS

The predicted area under the plasma concentration-time curve (AUC) and maximum (peak) concentration (C max) were reasonably consistent (<2-fold errors) with the reported values. Sensitivity analysis showed that gut transit time, hepatic enzyme activity, and renal function affected the pharmacokinetic characteristics of these drugs. Shortened gut transit time only decreased the AUC of controlled-released drugs and drugs with low absorption rates. Impairment of renal function markedly altered pharmacokinetics of drugs mainly eliminated via the kidneys.

CONCLUSION

All of these results indicate that the developed PBPK model can quantitatively predict pharmacokinetic alterations induced by diabetes.

Stress-strain analysis of contractility in the ileum in response to flow and ramp distension in streptozotocin-induced diabetic rats--association with advanced glycation end product formation

This study compared the ileal contractility and analyzed the association between contractility with advanced glycation end product (AGE) formation in normal and streptozotocin (STZ)-induced diabetic rats. Nine STZ-induced diabetic rats (Diabetes group) and 9 normal rats (Normal group) were used. The motility experiments were carried out on ileums in organ baths containing physiological Krebs solution. Ileal pressure and diameter changes were obtained from basic, flow-induced and ramp distension-induced contractions. The frequency and amplitude of contractions were analyzed from pressure-diameter curves. Distension-induced contraction thresholds and maximum contraction amplitude of basic and flow-induced contractions were calculated in terms of stress and strain. AGE and its receptor (RAGE) in the layers were detected by immunohistochemistry staining. The maximum stress of flow-induced contractions was lowest in the Diabetes Group (P<0.05). During ramp distension, the pressure and stress thresholds and Young's modulus to induce phasic contraction were lowest in the Diabetes Group (P<0.05 and P<0.01). AGE and RAGE expressions in the different ileum layers were highest in the Diabetes group. The contraction pressure and stress thresholds were significantly associated with AGE expression in the muscle layer and RAGE expression in mucosa epithelium and neurons. The diabetic intestine was hypersensitive to distension for contraction induction. However, the contraction force produced by smooth muscle was lowest in diabetic rats. Increased AGE/RAGE expression was associated with the contractility changes in diabetic rats.

Stress-strain analysis of jejunal contractility in response to flow and ramp distension in type 2 diabetic GK rats: effect of carbachol stimulation

Investigation of intestinal motility in a genetic model of GK rats abandons the possible neurotoxic effect of streptozotocin in streptozotocin-induced diabetic model. Seven GK male rats (GK group) and nine normal Wistar rats (Normal group) were used in the study. The motility experiments were carried out in an organ bath containing physiological Krebs solution. Before and after 10(-5)M carbachol application, the pressure and diameter changes of jejunum were obtained in relation to (1) basic contraction, (2) flow-induced contraction with different outlet resistance pressures and (3) contractions induced by ramp distension. The frequency and amplitude of contractions were analyzed from pressure-diameter curves. Distension-induced contraction thresholds and maximum contraction amplitude of basic and flow-induced contractions were calculated in terms of stress and strain. (1) The contraction amplitude increased to the peak value in less than 10s after adding carbachol. More than two peaks were observed in the GK group. (2) Carbachol decreased the pressure and stress threshold and Young's modulus in the GK group (P<0.01). (3) Carbachol increased the maximum pressure and stress of flow-induced contractions at most outlet pressure levels in both two groups (P<0.001). Furthermore, the flow-induced contractions were significantly bigger at low outlet pressure levels in GK group (P<0.05 and P<0.01). (4) The contraction frequency, the strain threshold and the maximum contraction strain did not differ between the two groups (P>0.05) and between before and after carbachol application (P>0.05). In GK diabetic rats, the jejunal contractility was hypersensitive to flow and distension stimulation after carbachol application.

Assessment of small bowel motility in patients with chronic intestinal pseudo-obstruction using cine-MRI

OBJECTIVES

Chronic intestinal pseudo-obstruction (CIPO) is a rare, serious motility disorder, with life-threatening complications over time. However, lack of an established, non-invasive diagnostic method has caused delays in the diagnosis of this intractable disease. Cine-magnetic resonance imaging (MRI) is an emerging technique, with a potential to evaluate the motility of the entire bowel. We compared small bowel motility in healthy volunteers, patients with irritable bowel syndrome (IBS), and those with CIPO, using cine-MRI, and evaluated the usefulness of cine-MRI as a novel diagnostic method for CIPO.

METHODS

Twelve healthy volunteers, IBS patients, and CIPO patients prospectively underwent cine-MRI at 1.5 T. Luminal diameter, contraction ratio, and contraction cycle were measured and compared between the groups.

RESULTS

Cine-MRI provided sufficient dynamic images to assess the motility of the entire small bowel. Luminal diameter (mean±s.d.) in CIPO patients was significantly higher than that in healthy volunteers and IBS patients (43.4±14.1, 11.1±1.5, and 10.9±1.9 mm, respectively), and contraction ratio was significantly lower in CIPO patients than that in healthy volunteers and IBS patients (17.1±11.0%, 73.0±9.3%, and 74.6±9.4%, respectively). No significant differences were observed in the contraction cycle.

CONCLUSIONS

This study is the first to assess the clinical utility of cine-MRI in CIPO patients. Cine-MRI clearly detected contractility impairments in CIPO patients. Cine-MRI is noninvasive, radiation-free, and can directly evaluate the entire small bowel peristalsis, and can detect the affected loops at a glance; therefore, it might be extremely useful for the diagnosis and follow-up of CIPO patients in clinical practice.

Enhanced Intestinal Motility during Oral Glucose Tolerance Test after Laparoscopic Sleeve Gastrectomy: Preliminary Results Using Cine Magnetic Resonance Imaging

Background

Enhanced secretion of glucagon-like peptide-1 (GLP-1) has been suggested as a possible mechanism underlying the improvement in type 2 diabetes mellitus (T2DM) after laparoscopic sleeve gastrectomy (LSG). However, the reason for enhanced GLP-1 secretion during glucose challenge after LSG remains unclear because LSG does not include intestinal bypass. In this study, we focused on the effects of LSG on GLP-1 secretion and intestinal motility during the oral glucose tolerance test (OGTT) using cine magnetic resonance imaging (MRI) before and 3 months after LSG.

Methods

LSG was performed in 12 obese patients with a body mass index >35 kg/m². Six patients had T2DM. OGTT was performed before and 3 months after the surgery. Body weight, hemoglobin A1c (HbA1c), and GLP-1 levels during OGTT were examined, and intestinal motility during OGTT was assessed using cine MRI.

Results

Body weight was significantly decreased after surgery in all the cases. HbA1c was markedly decreased in all the diabetic subjects. In all cases, GLP-1 secretion during OGTT was enhanced and cine MRI showed markedly increased intestinal motility at 15 and 30 min during OGTT after LSG.

Conclusions

LSG leads to accelerated intestinal motility and reduced intestinal transit time, which may be involved in the mechanism underlying enhanced GLP-1 secretion during OGTT after LSG.

Effect of diabetes mellitus on pharmacokinetic and pharmacodynamic properties of drugs

The effects of diabetes mellitus on the pharmacokinetics and pharmacodynamics of drugs have been well described in experimental animal models; however, only minimal data exist for humans and the current knowledge regarding the effects of diabetes on these properties remains unclear. Nevertheless, it has been observed that the pharmacokinetics and pharmacodynamics of drugs are changed in subjects with diabetes. It has been reported that diabetes may affect the pharmacokinetics of various drugs by affecting (i) absorption, due to changes in subcutaneous adipose blood flow, muscle blood flow and gastric emptying; (ii) distribution, due to non-enzymatic glycation of albumin; (iii) biotransformation, due to regulation of enzymes/transporters involved in drug biotransformation; and (iv) excretion, due to nephropathy. Previously published data also suggest that diabetes-mediated changes in the pharmacokinetics of a particular drug cannot be translated to others. Although clinical studies exploring the effect of diabetes on pharmacodynamics are still very limited, there is evidence that disease-mediated effects are not limited only to pharmacokinetics but also alter pharmacodynamics. However, for many drugs it remains unclear whether these influences reflect diabetes-mediated changes in pharmacokinetics rather than pharmacodynamics. In addition, even though diabetes-mediated pharmacokinetics and pharmacodynamics might be anticipated, it is important to study the effect on each drug and not generalize from observed data. The available data indicate that there is a significant variability in drug response in diabetic subjects. The discrepancies between individual clinical studies as well as between ex vivo and clinical studies are probably due to (i) the restricted and focused population of subjects in clinical studies; (ii) failure to consider type, severity and duration of the disease; (iii) histopathological characteristics generally being missing; and (iv) other factors such as varying medication use, dietary protein intake, age, sex and obesity. The obesity epidemic in the developed world has also inadvertently influenced the directions of pharmacological research. This review attempts to map new information gained since Gwilt published his paper in Clinical Pharmacokinetics in 1991. Although a large body of research has been conducted and significant progress has been made, we still have to conclude that the available information regarding the effect of diabetes on pharmacokinetics and pharmacodynamics remains unclear and further clinical studies are required before we can understand the clinical significance of the effect. An understanding of diabetes-mediated changes as well as of the source of the variability should lead to the improvement of the medical management and clinical outcomes in patients with this widespread disease.

Regular insulin, rather than rapid-acting insulin, is a suitable choice for premeal bolus insulin in lean patients with type 2 diabetes mellitus

The aim of the present study was to compare the usefulness of premeal rapid‐acting and regular insulin in type 2 diabetes patients. A total of 56 type 2 diabetic patients were investigated during hospitalization. Premeal rapid‐acting insulin was applied instead of other medications. Premeal insulin was titrated to adjust premeal and bedtime blood glucose levels to 81–120 mg/dL. Premeal rapid‐acting insulin was changed to regular insulin just before a meal at the same dosage if the postmeal blood glucose level was lower than the premeal blood glucose level. A total of 15 patients changed to regular insulin, and 41 patients continued rapid‐acting insulin. The blood glucose level was comparable between these two groups. Body mass index was significantly lower in the patients using regular insulin. According to the multivariate logistic regression analysis, low body mass index was an independent variable accounting for the usefulness of regular insulin. Regular insulin, rather than rapid‐acting insulin, is a suitable choice for premeal insulin in lean type 2 diabetic patients.

Assessment of small bowel motility function with cine-MRI using balanced steady-state free precession sequence

PURPOSE

To evaluate the use of cine-magnetic resonance imaging (MRI) with a steady-state free precession sequence to monitor and assess small bowel motility.

MATERIALS AND METHODS

Sequential MRI, using a balanced steady-state free precession sequence, was performed in eight healthy male volunteers at 0, 15, 30, 45, and 60 minutes after oral administration of 1500 mL of nonabsorbable fluid to monitor small bowel contractions. Using the cine-mode display, small bowel contractions were reviewed and the luminal diameter was measured on each image to obtain frequency and amplitude of bowel contractions.

RESULTS

The oral preparation was well tolerated without major complications. Cine-MRI provided high temporal, spatial, and contrast resolution for monitoring bowel contractions. Mean values with standard deviations of frequency and amplitude of bowel contractions were 6.0 ± 2.98/min and 10.4 ± 4.53 mm, respectively, and were 5.1 ± 3.38/min and 9.59 ± 5.57 mm at the jejunal loops and 6.9 ± 2.22/min and 11.2 ± 3.06 mm at the ileal loops. With the passage of luminal fluid, frequency of bowel contractions decreased and the bowels tended to pause their contractions.

CONCLUSION

Cine-MRI provides sufficient dynamic images to observe small bowel contractions. Measurement of bowel caliber permits calculation of amplitude and frequency of the contractions for characterization and quantitative assessment of small bowel motility function.

The effect of mosapride citrate on constipation in patients with diabetes

OBJECTIVE

Constipation is one of the most common gastrointestinal complications suspected to degrade the quality of life in diabetic patients. Mosapride citrate is a novel selective 5-HT4 receptor agonist, which enhances gastric emptying and motility in the upper gastrointestinal tract facilitating acetylcholine release from the enteric cholinergic neurons. Since the receptors of 5-HT4 have been recently found in the lower intestine including the rectum in humans, we tested if mosapride improves constipation in diabetic patients.

PATIENTS AND METHODS

Diabetic patients with constipation were treated with mosapride citrate (15 mg/day, n=20) or domperidone (30 mg/day, n=12) as controls for 8 weeks. Bowel frequency was monitored and gastrointestinal symptoms were evaluated by Gastrointestinal Symptoms Rating Scale (GSRS).

RESULTS

Administration of mosapride resulted in increased bowel frequency after 4 and 8 weeks of administration, while no change was seen in the control group. Mosapride increased bowel frequency in even patients with diabetic polyneuropathy. Mosapride improved reflux and constipation evaluated by GSRS. As previously reported, glycemic control also improved by mosapride in these patients.

CONCLUSIONS

Administration of mosapride increased bowel frequency and ameliorated symptoms of reflux and constipation possibly stimulating the lower intestine. Given that mosapride has those beneficial aspects, it may be a useful prokinetic agent in treating diabetic patients with constipation.

Probiotic Pre-treatment Reduces Gliclazide Permeation (ex vivo) in Healthy Rats but Increases It in Diabetic Rats to the Level Seen in Untreated Healthy Rats

Aim

To investigate the influence of probiotic pre-treatment on the permeation of the antidiabetic drug gliclazide in healthy and diabetic rats.

Methods

Wistar rats (age 2–3 months, weight 350 ± 50 g) were randomly allocated into one of 4 groups (N = 16 each group): healthy control, healthy probiotic, diabetic control, and diabetic probiotic. Probiotics (75 mg/kg, equal quantities of Lactobacillus acidophilus, Bifidobacterium lactis, and Lactobacillus rhamnosus) were administered twice a day for three days to the appropriate groups after diabetes had been induced with alloxan i.v. 30 mg/kg. Rats were sacrificed, ileal tissues mounted in Ussing chambers and gliclazide (200 µg/mL) was administered for the measurement of the mucosal to serosal absorption Jss^(MtoS) and serosal to mucosal secretion Jss^(StoM) of gliclazide.

Results

Treatment of healthy rats with probiotics reduced Jss^(MtoS) of gliclazide from 1.2 ± 0.3 to 0.3 ± 0.1 µg/min/cm² (P < 0.01) and increased Jss^(StoM)from 0.6 ± 0.1 to 1.4 ± 0.3 (P < 0.01) resulting in net secretion while, in diabetic tissues, treatment with probiotics increased both Jss^(MtoS) and Jss^(StoM)fluxes of gliclazide to the comparable levels of healthy tissues resulting in net absorption.

Discussion

In healthy rats, the reduction in Jss^(MtoS) after probiotics administration could be explained by the production of bacterial metabolites that upregulate the mucosal efflux drug transporters Mrp2 that control gliclazide transport. In diabetic rats, the restored fluxes of gliclazide after probiotic treatment, suggests the normalization of the functionality of the drug transporters resulting in a net absorption.

Conclusion

Probiotics may alter gliclazide transport across rat ileal tissue studied ex vivo.

Disturbed gastrointestinal motility and decreased interstitial cells of Cajal in diabetic db/db mice

BACKGROUND AND AIM

Diabetes mellitus (DM) often causes gastrointestinal dysmotility. Interstitial cells of Cajal (ICC), which express c-kit receptor tyrosine kinase (KIT), are considered the pacemaker cells for gastrointestinal movement. The present study was designed to determine the role of ICC in the pathogenesis of gastroenteropathy in type 2 DM.

METHODS

We examined C57BL/KsJ-db/db mice as a model for type 2 DM. Gastrointestinal motility was evaluated by measuring gastric emptying, whole gut transit time, and isometric tension of the isolated small intestine. The area of KIT-positive cells in the gastrointestinal tract was examined by image analysis of fluorescent immunohistochemistry. The mRNA expression of KIT ligand, stem cell factor (SCF), in the gastrointestinal tract was quantified by real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Compared with 12-week-old db/+m control mice, diabetic db/db mice of the same age exhibited delayed gastric emptying, prolonged whole gut transit time, irregular frequency of isometric tension in the small intestine, smaller areas of KIT-positive cells in the antrum, small intestine, and colon, and lower mRNA expression levels of SCF in the small intestine and colon.

CONCLUSIONS

We demonstrated disturbed gastrointestinal motility in db/db mice with reduced areas of ICC and expression of SCF. Our results suggest the involvement of ICC in the gastroenteropathy of type 2 DM.

Effect of tegaserod on colonic transit time in male patients with constipation-predominant irritable bowel syndrome

BACKGROUND AND AIMS

Tegaserod is approved for the treatment of constipation-predominant irritable bowel syndrome (C-IBS) in females. The aim of this study was to evaluate the effect of tegaserod on colonic transit time (CTT) and symptoms in male patients with C-IBS.

METHODS

Forty-four males with C-IBS (Rome II) were enrolled. After a baseline washout period of 2 weeks, 40 patients were randomized to 6 mg twice daily of tegaserod or placebo for 12 weeks. Daily bowel habits and weekly satisfactory relief of symptoms were recorded. Total and segmental CTT were measured using radiopaque markers at baseline and after treatment.

RESULTS

The mean +/- SD for the total colonic, right colonic, left colonic and rectosigmoid transit time (in hours) were 18.96 +/- 3.92, 7.74 +/- 1.55, 5.64 +/- 1.51 and 5.58 +/- 2.2 in the tegaserod group compared to 22.47 +/- 3.73, 9.69 +/- 2.33, 6.6 +/- 1.32 and 6.18 +/- 2.22 in the placebo group at the end of 12 weeks. There was a statistically significant difference in the total, right and left CTT in the tegaserod group (P < 0.05) at the end of treatment. Global satisfactory relief at the end of 12 weeks was 75% in the tegaserod group and 50% in the placebo group (P > 0.05). Greater stool frequency occurred in the tegaserod group (P > 0.05). There was a significant decrease in the stool consistency at the end of 12 weeks in patients treated with tegaserod (P < 0.05).

CONCLUSIONS

Tegaserod causes significant acceleration of CTT in male patients with C-IBS. Although there was a trend towards improvement in bowel symptoms in the treated group, this effect was not statistically significant.

Effect of interference in heme oxygenase on colonic dysfunction of diabetic rats

AIM: To investigate the effect of heme oxygenase (HO) interference on the colonic dysfunction in rats with diabetes mellitus (DM).

METHODS: DM model was established by intraperitoneal injection of streptozotocin (STZ) in Sprague and Dawley rats. Six weeks later, the diabetic rats were validated to be suffered with gastrointestinal dysfunction using charcoal (Indian ink) propulsion experiment. Then the rest rats were randomly divided into 4 groups, named group A (normal control), B (diabetic rats without interference), C (diabetic rats administrated with Hemin, the inducer of HO) and D [diabetic rats administrated with zinc protoporphyrin Ⅸ (ZnPP Ⅸ), the inhibitor of HO]. The weight and blood glucose of the rats were tested. Three more weeks later, the motilities of the strips isolated from the proximal and distal colon were recorded. The level of HO in the colon was also detected by immunohistochemistry and Western blot.

RESULTS: The model of diabetic rats suffered with gastrointestinal dysfunction was successfully duplicated. Administration of Hemin or ZnPP Ⅸ had no effect on the weight or blood glucose of diabetic rats (P > 0.05). There was no significant difference in HO-2 expression of the distal colon between the diabetic rats with or/and without interference (P > 0.05). But in comparison with the controls, HO-2 expression of the proximal colon in group B, C or D was significantly declined (Western blot: 1.20 ± 0.09, 1.08 ± 0.11, 1.10 ± 0.08 vs 1.66 ± 0.14, P < 0.05). The colonic expression of HO-1 was not significantly different between group A and B (Western blot: proximal 0.22 ± 0.02 vs 0.22 ± 0.03; distal 0.23 ± 0.03 vs 0.23 ± 0.03; both P > 0.05), but HO-1 expression was markedly higher in group C (proximal 0.66 ± 0.09; distal 0.47 ± 0.07) than that in the former two groups (P < 0.05); the expression of HO-1 was hardly found in group D. In comparison with those in group B, the gastrointestinal propulsion rate (54.4% ± 2.9% vs 63.0% ± 1.2%, P < 0.05), spontaneous contraction frequencies, amplitudes, and reaction to acetylcholine of colonic smooth muscles were dramatically declined in group C (P < 0.05), while those (gastrointestinal propulsion rate: 72.5% ± 2.6% vs 63.0% ± 1.2%, P < 0.05) in group D were markedly improved (all P < 0.05).

CONCLUSION: HO interference has no effect on the body weight or blood glucose of diabetic rats. The induction of HO-1 may aggravate the decline of colonic motility in diabetic rats, while HO-1 blockage may improve the declined colonic motility.

Upper gastrointestinal sensory-motor dysfunction in diabetes mellitus

Gastrointestinal (GI) sensory-motor abnormalities are common in patients with diabetes mellitus and may involve any part of the GI tract. Abnormalities are frequently sub-clinical, and fortunately only rarely do severe and life-threatening problems occur. The pathogenesis of abnormal upper GI sensory-motor function in diabetes is incompletely understood and is most likely multi-factorial of origin. Diabetic autonomic neuropathy as well as acute suboptimal control of diabetes has been shown to impair GI motor and sensory function. Morphological and biomechanical remodeling of the GI wall develops during the duration of diabetes, and may contribute to motor and sensory dysfunction. In this review sensory and motility disorders of the upper GI tract in diabetes is discussed; and the morphological changes and biomechanical remodeling related to the sensory-motor dysfunction is also addressed.

Comparison between coefficient of R-R interval variation and gastric emptying in type 2 diabetes mellitus patients

BACKGROUND

Autonomic neuropathy is a common complication of diabetes mellitus (DM).

METHOD

To clarify the relationship between cardiovascular autonomic function and gastric emptying rate, we investigated the gastric emptying and coefficient of R-R interval variation (CV(RR)) of 84 type 2 diabetic patients: 28 cases without peripheral neuropathy and 56 cases with peripheral neuropathy. All patients were subjected to a gastric emptying test according to the marker method (administration of a capsule containing 20 pieces of radiopaque marker during breakfast, followed by abdominal X-ray imaging 3 and 5 h later). Patients had their CV(RR) assessed at rest and during deep breathing.

RESULTS

Gastric emptying scores were significantly correlated with CV(RR) during deep breathing and with the duration of DM, but neither age nor CV(RR) at rest in all patients. Gastric emptying scores and CV(RR) at rest and during deep breathing in patients with peripheral neuropathy were significantly deteriorated than those in patients without peripheral neuropathy. A significant correlation between gastric emptying and CV(RR) during deep breathing could be observed in the patients with peripheral neuropathy, but not in those without it.

CONCLUSIONS

These findings showed that CV(RR) during deep breathing might be a good indicator of diabetic gastropathy and that peripheral neuropathy was closely related with cardiac and gastric autonomic neuropathy in the type 2 diabetic patients.

Small bowel motility assessment with magnetic resonance imaging

PURPOSE

To assess primarily the feasibility of magnetic resonance imaging (MRI) as a tool to monitor small bowel peristaltic motion and secondarily to validate this technique by demonstrating drug-induced motility changes.

MATERIALS AND METHODS

After a standardized oral preparation of Ispaghula husk (Metamucil) and meglumine gadoterate (Gd-DOTA; Dotarem), 10 volunteers underwent dynamic MRI using a two-dimensional turbofast field echo (TFE) sequence with a slice repetition time of 500 msec. Intraluminal cross-sectional caliber changes over time were assessed allowing quantification of the peristaltic frequencies and amplitudes of the small gut on various regions of interest. Pharmacologically induced alterations of the peristaltic motion after spasmolytics and gastrokinetic motion enhancers were investigated.

RESULTS

Small bowel diameter measurement resulted in a peristalsis of 10.96 (SD = +/-2.51) waves per minute, oscillating regularly with mean amplitudes of 6.65 mm (SD = +/-1.15 mm). Peristaltic frequency in normal individuals is consistent with that observed with other techniques. Intravenous administration of scopolamine butylbromide (= hyoscine butylbromide/Buscopan) resulted in small bowel paralysis within 21.3 seconds (SD = +/-2.8 seconds). Prokinetic effect of intravenous metoclopramide (Paspertin) after Buscopan paralysis was tested in one volunteer, characterized by a slow recovery of peristalsis, which propagated from the proximal to the distal segments and enhanced contraction amplitudes.

CONCLUSION

Dynamic MRI allows observing and quantifying small bowel peristalsis, characterizing motion patterns, and monitoring the effects of interfering factors such as drugs.

Enhanced colonic peristalsis by impairment of nitrergic enteric neurons in spontaneously diabetic rats

Changes in enteric neurons containing various neurotransmitters in the colon have been described in diabetic rats; however, how these changes are related to colonic motility disorders remains unclear. Nitric oxide (NO) is known to be an important inhibitory neurotransmitter in the enteric nervous system. In the present study, we investigated the peristaltic reflex using our modified Trendelenburg's method to evaluate the differences in enteric nitrergic neurons of the distal colon between spontaneously diabetic rats and their sibling control rats. We measured maximum intraluminal pressure, threshold pressure and propagation distance of the reflex contraction. These diabetic rats showed a greater maximum intraluminal pressure than that in the control rats. NG nitro-L-arginine methyl ester (L-NAME) significantly increased the maximum pressure in the control rats. Although L-arginine did not change the maximum pressure, sodium nitroprusside (SNP) significantly decreased it in these diabetic rats. Nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase reactivities in the myenteric plexus were much weaker in the diabetic rats than those in the control rats. These results indicate that the colonic peristaltic reflex is enhanced by impairment of enteric nitrergic inhibitory neurons in spontaneously diabetic rats.