Increased nutrient sensitivity and plasma concentrations of enteral hormones during duodenal nutrient infusion in functional dyspepsia

Effects of ondansetron on symptoms during a gastric emptying study and enteral lipid challenge and on daily symptoms in diabetic gastroenteropathy

BACKGROUND

This study compared the effects of ondansetron and placebo in patients with diabetes mellitus and symptoms of dyspepsia (diabetic gastroenteropathy [DGE]).

METHODS

We performed a randomized, double-blinded, placebo-controlled study of ondansetron tablets (8 mg) three times daily for 4 weeks in DGE patients. Symptoms were assessed with the Gastroparesis Cardinal Symptom Index daily diaries. Gastric emptying (GE) of solids (scintigraphy) and duodenal lipid infusions (300 kcal over 2 h) were each assessed twice, with placebo and ondansetron. Drug effects on GE, symptoms during the GE study and during lipid infusion, and daily symptoms were analyzed.

KEY RESULTS

Of 41 patients, 37 completed both GE studies and one completed 1; 31 completed both lipid infusions and four only placebo; and all 35 randomized patients completed 4 weeks of treatment. Compared to placebo, ondansetron reduced the severity of fullness (p = 0.02) and belching (p = 0.049) during lipid infusion but did not affect GE T1/2. Both ondansetron and placebo improved daily symptoms versus the baseline period (p < 0.05), but the differences were not significant. In the analysis of covariance of daily symptoms during the treatment period, the interaction term between treatment and the acute effect of ondansetron on symptoms during lipid challenge was significant (p = .024).

CONCLUSIONS & INFERENCES

Ondansetron significantly reduced fullness during enteral lipid infusion in patients with DGE. Overall, ondansetron did not improve daily symptoms versus placebo. But patients in whom ondansetron improved symptoms during enteral lipid challenge were perhaps more likely to experience symptom relief during daily treatment.

Glycemic Control in Diabetic Patients Receiving a Diabetes-Specific Nutritional Enteral Formula: A Case Series in Home Care Settings

BACKGROUND AND AIM

In patients with Diabetes Mellitus (DM), Enteral Nutrition (EN) is associated with less hyperglycemia and lower insulin requirements compared to Parenteral Nutrition (PN). The primary aim of this study was to assess changes in glycemic control (GC) in DM patients on EN therapy. The secondary objectives included evaluating the impact of the specialized formula on various clinical parameters and the tolerability of the nutritional formula by monitoring potential gastrointestinal side effects.

METHODS

We report a case series on the effects of a Diabetes-Specific Formula (DSF) on GC, lipid profile (LP), and renal and hepatic function in a DM cohort receiving EN support.

RESULTS

Twenty-two DM subjects with total dysphagia (thirteen men, nine women) on continuous EN were observed. The use of a DSF in EN was associated with an improvement in glycemic indices across all patients studied, leading to a reduction in average insulin demand. No hospitalizations were reported during the study period.

CONCLUSION

The study demonstrated that the use of DSFs in a multi-dimensional home care management setting can improve glycemic control, reduce glycemic variability and insulin need, and positively impact the lipid profile of the DM cohort. The metabolic improvements were supported by the clinical outcomes observed.

Small intestinal bacterial overgrowth in diabetic gastroenteropathy

BACKGROUND

Although diabetic gastroenteropathy (DGE) is associated with small intestinal bacterial overgrowth (SIBO), most studies have evaluated SIBO with a hydrogen breath test, which may be affected by altered transit in DGE. The risk factors for the consequences of SIBO in DGE are poorly understood. We aimed to evaluate the prevalence of, risk factors for, and gastrointestinal symptoms associated with SIBO in patients with DGE.

METHODS

In 75 patients with DGE and dyspepsia, we tested for SIBO (≥105 colony forming units /mL of aerobic and/or anaerobic bacteria in a duodenal aspirate) and assessed gastric emptying (GE) of solids, symptoms during a GE study and during an enteral lipid challenge (300 kcal/2 h), and daily symptoms with a Gastroparesis Cardinal Symptom Index diary for 2 weeks. Symptoms and GE were compared in patients with versus without SIBO.

KEY RESULTS

Of 75 patients, 34 (45%) had SIBO, which was not associated with the use of proton pump inhibitors, daily symptoms, GE, or symptoms during a GE study. During enteral lipid challenge, severe nausea (p = 0.006), fullness (p = 0.02) and bloating (p = 0.009) were each associated with SIBO. Twenty patients (59%) with versus 13 (32%) without SIBO had at least one severe symptom during the lipid challenge (p = 0.006).

CONCLUSIONS & INFERENCES

Among patients with DGE 45% had SIBO, which was associated with symptoms during enteral lipid challenge but not with delayed GE, symptoms during a GE study, or daily symptoms. Perhaps bacterial products and even fatty acids are recognized by and activate mast cells that drive the increased lipid sensitivity in SIBO.

Meal related symptoms in youth with chronic abdominal pain: Relationship to anxiety, depression, and sleep dysfunction

OBJECTIVE

The objective of the current study was to describe meal-related symptoms in youth with chronic abdominal pain fulfilling criteria for a disorder of gut-brain interaction (DGBI) and their associations with anxiety, depression, and sleep disturbances.

METHODS

This was a retrospective evaluation of 226 consecutive patients diagnosed with an abdominal pain-associated DGBI. As part of routine care, all had completed a standardized symptom history, the Sleep Disturbances Scale for Children (utilized to assess for disorders of initiation and maintenance of sleep and excessive daytime somnolence) and the Behavior Assessment System for Children-Third Edition (utilized to assess for anxiety and depression). Four meal related symptoms were assessed: early satiety, postprandial bloating, postprandial abdominal pain, and postprandial nausea.

RESULTS

Overall, 87.6% of patients reported at least one meal related symptom and the majority reported at least three symptoms. All meal related symptoms were significantly related to each other. Postprandial pain and nausea were more often reported by females. Early satiety, postprandial bloating, and postprandial nausea, but not postprandial pain demonstrated significant though variable associations with anxiety, depression, disorders of initiation and maintenance of sleep, and disorders of excessive somnolence, but only in adolescents.

CONCLUSIONS

Meal related symptoms are very common in youth with abdominal pain-associated DGBIs. Early satiety, bloating, and postprandial nausea demonstrate variable associations with anxiety, depression, and disordered sleep while increased postprandial pain was not associated with psychologic or sleep dysfunction, suggesting a different pathway for symptom generation.

Nutrition and Disorders of Gut-Brain Interaction

BACKGROUND

Disorders of gut-brain interaction (DGBIs) have a complex pathophysiology that is often characterized by a relationship between food ingestion and triggering of symptoms. Understanding of the underlying mechanisms and the role of nutrients as a therapeutic target are rapidly evolving.

AIMS AND METHODS

We performed a narrative review of the literature using the following keywords, their acronyms, and their associations: nutrients, disorders of gut-brain interaction; functional dyspepsia; malabsorption; irritable bowel syndrome; diarrhea; constipation.

RESULTS

Functional dyspepsia displayed a significant correlation between volume, fat and/or wheat abundance, chemical composition of ingested food and symptoms of early satiety, fullness and weight loss. Carbohydrate malabsorption is related to enzyme deficiency throughout the GI tract. Food composition and richness in soluble vs. non-soluble fibers is related to constipation and diarrhea. The elimination of fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) has a significant and non-unidirectional impact on irritable bowel syndrome (IBS) symptoms.

CONCLUSIONS

Food volume, nutritive and chemical composition, and its malabsorption are associated with symptom generation in DGBIs. Further multicenter, randomized-controlled clinical trials are needed to clarify the underlying pathophysiology.

Review article: Functional dyspepsia-a gastric disorder, a duodenal disorder or a combination of both?

BACKGROUND

Functional dyspepsia (FD) is one of the most frequent conditions in gastroenterological outpatient health care. Most recent research in FD has shifted its focus to duodenal pathophysiological mechanisms, although current treatments still focus mainly the stomach.

AIM

The aim of the study was to provide a comprehensive overview of the pathophysiology of FD focusing on a paradigm shift from gastric towards duodenal mechanisms.

METHODS

We conducted a literature search in PubMed for studies describing mechanisms that could possibly cause FD.

RESULTS

The pathophysiology of FD remains incompletely understood. Recent studies show that duodenal factors such as acid, bile salt exposure and eosinophil and mast cell activation correlate with symptom pattern and burden and can be associated with gastric sensorimotor dysfunction. The evolving data identify the duodenum an interesting target for new therapeutic approaches. Furthermore, the current first-line treatment, that is proton pump inhibitors, reduces duodenal low-grade inflammation and FD symptoms.

CONCLUSION

Future research for the treatment of FD should focus on the inhibition of duodenal mast cell activation, eosinophilia and loss of mucosal integrity.

Mechanisms Underlying Food-Triggered Symptoms in Disorders of Gut-Brain Interactions

There has been a dramatic increase in clinical studies examining the relationship between disorders of gut-brain interactions and symptoms evoked by food ingestion in the upper and lower gastrointestinal tract, but study design is challenging to verify valid endpoints. Consequently, mechanistic studies demonstrating biological relevance, biomarkers and novel therapeutic targets are greatly needed. This review highlights emerging mechanisms related to nutrient sensing and tasting, maldigestion, physical effects with underlying visceral hypersensitivity, allergy and immune mechanisms, food-microbiota interactions and gut-brain signaling, with a focus on patients with functional dyspepsia and irritable bowel syndrome. Many patients suffering from disorders of gut-brain interactions exhibit these mechanism(s) but which ones and which specific properties may vary widely from patient to patient. Thus, in addition to identifying these mechanisms and the need for further studies, biomarkers and novel therapeutic targets are identified that could enable enriched patient groups to be studied in future clinical trials examining the role of food in the generation of gut and non-gut symptoms.

Duodenal Mucosal Barrier in Functional Dyspepsia

BACKGROUND & AIMS

In addition to gastric sensorimotor dysfunctions, functional dyspepsia (FD) is also variably associated with duodenal micro-inflammation and epithelial barrier dysfunction, the pathogenesis and clinical significance of which are unknown. Our hypothesis was that miRNAs and/or inflammation degrade epithelial barrier proteins, resulting in increased duodenal mucosal permeability in FD.

METHODS

We compared the duodenal mucosal gene expression and miRNAs, in vivo permeability (lactulose-mannitol excretion between 0 and 60 and 60 and 120 minutes after saccharide ingestion), ex vivo assessments (transmucosal resistance, fluorescein isothiocyanate [FITC]-dextran flux, and basal ion transport), and duodenal histology (light and electron microscopy) in 40 patients with FD and 24 controls.

RESULTS

Compared with controls, the mRNA expression of several barrier proteins (zonula occludens-1, occludin, claudin-12, and E-cadherin) was modestly reduced (ie, a fold change of 0.8-0.85) in FD with increased expression of several miRNAs (eg, miR-142-3p and miR-144-3-p), which suppress these genes. The urinary lactulose excretion and the lactulose:mannitol ratio between 60 and 120 minutes were greater in FD than in controls (P < .05). The FITC-dextran flux, which reflects paracellular permeability, was inversely correlated (r = -0.32, P = .03) with transmucosal resistance and directly correlated (r = 0.4, P = .02) with lactulose:mannitol ratio. Other parameters (mucosal eosinophils, intraepithelial lymphocytes, and mast cells, transmucosal resistance, FITC-dextran flux, average intercellular distance, and proportion of dilated junctions) were not significantly different between groups.

CONCLUSIONS

In FD, there is a modest reduction in the expression of several duodenal epithelial barrier proteins, which may be secondary to up-regulation of regulatory miRNAs, and increased small intestinal permeability measured in vivo.

Gastrointestinal hormones and regulation of gastric emptying

PURPOSE OF REVIEW

In this review, we evaluate recent findings related to the association between gastrointestinal hormones and regulation of gastric emptying.

RECENT FINDINGS

Motilin and ghrelin, which act during fasting, promote gastric motility, whereas most of the hormones secreted after a meal inhibit gastric motility. Serotonin has different progastric or antigastric motility effects depending on the receptor subtype. Serotonin receptor agonists have been used clinically to treat dyspepsia symptoms but other hormone receptor agonists or antagonists are still under development. Glucagon-like peptide 1 agonists, which have gastric motility and appetite-suppressing effects are used as a treatment for obesity and diabetes.

SUMMARY

Gastrointestinal hormones play an important role in the regulation of gastric motility. Various drugs have been developed to treat delayed gastric emptying by targeting gastrointestinal hormones or their receptors but few have been commercialized.

Postinfectious onset in functional dyspepsia is a risk factor for weight loss

BACKGROUND

Functional dyspepsia (FD) is differentiated into two subgroups: the postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS). Acute gastroenteritis and Helicobacter pylori (HP) infection have been identified as risk factors for FD. It is unclear how these risk factors relate to Rome IV subgroups and their clinical impact. We aimed to study the association of postinfectious FD (PI-FD) and HP status with clinical profiles and weight loss.

METHODS

Consecutive FD patients were assessed for symptom frequency and severity. Patients were identified as PDS, EPS or the overlap group according to severity scores. Additionally, PI history and HP status were determined.

RESULTS

In a cohort of 459 FD-patients, 36% were characterized as having PDS, 9% as having EPS and 55% showed overlap. PI onset and positive HP status were reported by, respectively, 20% and 14% of patients, not significantly differing between subgroups (respectively, p = 0.31 and p = 0.40). Weight loss was reported by 63% in PDS, 36% in EPS and 56% in overlap patients (p = 0.011). Only early satiety severity correlated with more severe weight loss in the PDS (r 0.31, p < 0.0001) and overlap group (r 0.38, p < 0.0001). PI-FD patients were more likely to experience weight loss (OR 2.27, p = 0.0013). HP status was not significantly associated with weight loss (p = 0.90).

CONCLUSION

In this cohort, PI onset of FD symptoms emerged as a risk factor for weight loss, but was not associated with the symptom patterns of PDS, EPS or overlap subgroups. Patients with HP infection were not more likely to experience important weight loss.

Relationship between symptoms during a gastric emptying study, daily symptoms and quality of life in patients with diabetes mellitus

AIMS

Gastric emptying is of limited utility for predicting the severity of symptoms in patients with diabetes mellitus and gastrointestinal symptoms. We evaluated the extent to which symptoms recorded during a ¹³ C-spirulina-based gastric emptying breath test (GEBT) or scintigraphy predicting the severity of daily symptoms in diabetes mellitus.

METHODS

Gastric emptying, symptoms during a gastric emptying study, either scintigraphy (n = 38) or GEBT (n = 111), and daily gastrointestinal symptoms were evaluated in 149 patients with diabetes mellitus and variably severe gastrointestinal symptoms.

KEY RESULTS

Gastric emptying was normal, delayed, and rapid in 37%, 52%, and 9% measured with the GEBT and 55%, 34%, and 11% of patients measured with scintigraphy; differences between GEBT and scintigraphy were not significant. Daily symptoms were moderately severe or more intense in 58% and 21% of patients undergoing scintigraphy and GEBT (P < 0.0001). Symptoms during the GEBT (46%) and emptying t_half (3%) explained 50% of the variance in daily symptoms in the GEBT group. In the scintigraphy group, symptoms explained 29% of this variance; the t_half was insignificant. Patients who reported that one or more symptoms were more severe than the others during the GE study were more likely (OR 3.98, 95% CI 2.16, 7.33) to report the same symptom(s) as being the most severe in the daily diary.

CONCLUSIONS

Symptoms during a GEBT and to a lesser extent during scintigraphy, but not gastric emptying predict the severity of daily symptoms and may serve as a biomarker in patients with diabetes mellitus.

Duodenal mucosal secretory disturbances in functional dyspepsia

BACKGROUND

There is increased recognition of duodenal disturbances (inflammation, altered mucosal protein expression, and chemosensitivity) in functional dyspepsia (FD). Besides sensorimotor functions, enteric submucosal neurons also regulate epithelial ion transport. We hypothesized that duodenal mucosal ion transport and expression of associated genes are altered in FD.

METHODS

Duodenal mucosal ion transport (basal and acetylcholine- and glucose-evoked changes in short-circuit current [Isc]) and expression of associated genes and regulatory miRNAs were evaluated in 40 FD patients and 24 healthy controls.

RESULTS

Basal Isc (FD: 88.2 [52.6] μA/cm² vs healthy: 20.3 [50.2] μA/cm² ; P ≤ .0001), acetylcholine-evoked Isc (FD: Emax 50.4 [35.8] μA/cm² vs healthy: 16.6 [15] μA/cm² ; P ≤ .001), and glucose-evoked Isc responses (FD: E_max 69.8 [42.1] μA/cm² vs healthy: 40.3 [24.6] μA/cm² ; P = .02) were greater in FD than in controls. The Emax for glucose was greater in FD patients on selective serotonin reuptake inhibitors. In FD, the mRNA expression of SLC4A7 and SLC4A4, which transport bicarbonate into cells at the basolateral surface, and the apical anion exchanger SLC26A3 were reduced (false discovery rate <0.05), the serotonin receptor HTR4 was increased, and the serotonin transporter SLC6A4 was decreased. Selected miRNAs (hsa-miR-590-3p, hsa-miR-32-5p) that target genes associated with ionic transport were upregulated in FD.

CONCLUSIONS

Compared to controls, FD patients had greater baseline and agonist-evoked duodenal mucosal secretory responses. These findings may be explained by reduced gene expression, which would be anticipated to reduce luminal bicarbonate secretion. The upregulated miRNAs may partly explain the downregulation of these genes in FD.

The Role of GI Peptides in Functional Dyspepsia and Gastroparesis: A Systematic Review

Functional dyspepsia (FD) and gastroparesis (GP) are common disorders of the upper gastrointestinal tract. The pathophysiology of these conditions is likely to be heterogenous, and factors such as altered motility, sensitivity and response to nutrition have been identified as putative underlying mechanisms. Motility, sensitivity as well as responses to nutrition can be influenced or mediated by peptide hormones and serotonin released from the gastrointestinal mucosa. This review summarizes the role of GI peptides in functional dyspepsia and gastroparesis. In most studies, the levels of somatostatin, ghrelin, and motilin did not differ between healthy volunteers and FD or GP patients, but higher symptom burden was often correlated with higher peptide levels. Ghrelin and motilin receptor agonists showed promising results in improvement of the gastric emptying, but the link with improvement of symptoms is less predictable. Serotonin agonists have a potential to improve symptoms in both FD and idiopathic gastroparesis. Drugs acting on the GLP-1 and on the PYY receptors deserve further investigation. There is a need for systematic large scale studies.

Utility of the plasma pancreatic polypeptide response to modified sham feeding in diabetic gastroenteropathy and non-ulcer dyspepsia

BACKGROUND

The relationship between cardiovascular and gastrointestinal (ie, plasma pancreatic polypeptide [PP] response to modified sham feeding [MSF]) indices of vagal function is unclear. Hyperglycemia inhibits PP secretion via vagally mediated mechanisms. Our aims were to (a) compare the PP response, (b) its relationship with glycemia, and (c) the relationship between PP response to MSF, gastric emptying (GE) of solids, and symptoms during GE study in healthy controls, patients with diabetic gastroenteropathy (DM), and non-ulcer dyspepsia (NUD).

METHODS

In 24 healthy controls, 40 DM, and 40 NUD patients, we measured plasma PP concentrations during MSF, cardiovagal functions, GE, and symptoms during a GE study.

KEY RESULTS

Baseline PP concentrations were higher in DM than in controls and NUD (P = .01), and in type 2 than in type 1 DM patients (P < .01). The PP increment during MSF was normal (≥20 pg/mL) in 70% of controls, 54% of DM, and 47% of NUD patients. Overall, the PP response and cardiovagal tests were concordant (P = .01). Among patients with a reduced PP increment with MSF, 7/10 of T1DM and 1/7 of T2DM patients had moderate or severe cardiovagal dysfunctions (P < .05). The PP response to MSF was not associated with GE.

CONCLUSIONS & INFERENCES

Up to 30% of healthy controls have a reduced PP increment during MSF, limiting the utility of this test to detect vagal injury. The PP response is more useful when it is normal than abnormal. A reduced PP response is more likely to be associated with cardiovagal dysfunctions in T1DM than in T2DM.

Association between allelic variants in the glucagon-like peptide 1 and cholecystokinin receptor genes with gastric emptying and glucose tolerance

BACKGROUND

Nutrient-mediated release of cholecystokinin and glucagon-like peptide-1 (GLP-1) regulates gastric emptying (GE) via duodenogastric feedback mechanisms; GLP-1 also regulates postprandial insulin secretion. Some patients with functional upper gastrointestinal symptoms have impaired glucose tolerance during enteral dextrose infusion. Our hypothesis was that variants in CCK, GLP-1, and TCF7L2 (transcription factor 7-like 2 locus), which is associated with greatest genetic risk for development of type 2 diabetes mellitus, are associated with GE and independently with glucose tolerance. Our aims were to evaluate the associations between these GE, glucose tolerance, and these single nucleotide polymorphisms (SNPs).

METHODS

Genetic variants, scintigraphic GE of solids, plasma glucose, insulin, and GLP-1 during enteral dextrose infusion (75gm over 2 hours) were measured. GE and enteral dextrose infusion were, respectively, evaluated in 44 (27 controls and 17 patients with functional dyspepsia or nausea) and 42 (28 controls, 14 patients) participants; of these, 51 participants consented to assessment of SNPs. Four functional SNPs were studied: rs6923761 and rs1042044 at GLP-1 receptor, rs7903146 (TCF7L2), and rs1800857 (CCK receptor).

KEY RESULTS

Gastric emptying was normal in 38, rapid in 4, and delayed in two participants; 38 had normal, and four had impaired glucose tolerance. The T allele at rs7903146 (TCF7L2) was non-significantly associated (P = .14) with faster GE. The associations between SNPs and demographic variables, GE t_half , glucose tolerance and plasma GLP1 levels were not significant.

CONCLUSIONS & INFERENCES

There is a trend toward an association between faster GE and the diabetes-associated allele at rs7903146 in TCF7L2. However, these SNPs were not associated with plasma glucose or GLP1 concentrations during enteral dextrose infusion.

Duodenal nutrient exposure contributes to enhancing gastric accommodation

BACKGROUND

The gastric accommodation reflex consists of a relaxation which creates a reservoir for the ingested food before emptying to the duodenum occurs. The mechanisms that control gastric accommodation are not fully understood. This study aims to use intragastric pressure (IGP) measurement and pyloric balloon obstruction to determine the contribution of duodenal nutrient exposure to gastric accommodation and meal-induced satiation.

METHODS

Two conditions were tested in 11 healthy subjects (28.3 ± 3.2 years; 23.6 ± 0.7 kg/m² ; four females). IGP was measured during an intragastric nutrient drink (ND) infusion at a constant rate (60 mL/min) in the presence of a deflated (control) or inflated (pyloric obstruction) balloon placed into the pylorus. During the study, subjects filled out Likert scales for satiation scores and visual analogue scale for 9 epigastric symptoms (hunger, expected amount to eat, satiation, bloating, fullness, nausea, belching, gastric cramps, and pain) before and during ND infusion until maximal satiation.

KEY RESULTS

During pyloric obstruction, the IGP drop and the area above the IGP curve (AAC) were significantly smaller compared with the control condition (6.7 ± 1.0 mm Hg vs3.6 ± 0.8 mm Hg, P = .03 and 69.7 ± 13.5 mm Hg × min vs 20.1 ± 9.0 mm Hg × min, P = .001, respectively). Pyloric obstruction decreased nutrient tolerance compared with the control condition (787.9 ± 73.1 mL vs 970.9 ± 79.2 mL, respectively, P < .05). Pyloric obstruction increased symptoms of bloating (1.3 ± 0.4 vs 2.6 ± 0.6; P = .04), fullness (2.3 ± 0.5 vs 3.6 ± 0.3; P = .03), and nausea (0.4 ± 0.2 vs 1.3 ± 0.4; P = .04) compared to control.

CONCLUSION & INFERENCES

Duodenal nutrient exposure contributes to enhancing gastric accommodation. Preventing the passage of nutrients from the stomach to the duodenum inhibits gastric accommodation and increases meal-induced satiation, bloating, nausea, and fullness.

Diabetic Gastroparesis

This review covers the epidemiology, pathophysiology, clinical features, diagnosis, and management of diabetic gastroparesis, and more broadly diabetic gastroenteropathy, which encompasses all the gastrointestinal manifestations of diabetes mellitus. Up to 50% of patients with type 1 and type 2 DM and suboptimal glycemic control have delayed gastric emptying (GE), which can be documented with scintigraphy, 13C breath tests, or a wireless motility capsule; the remainder have normal or rapid GE. Many patients with delayed GE are asymptomatic; others have dyspepsia (i.e., mild to moderate indigestion, with or without a mild delay in GE) or gastroparesis, which is a syndrome characterized by moderate to severe upper gastrointestinal symptoms and delayed GE that suggest, but are not accompanied by, gastric outlet obstruction. Gastroparesis can markedly impair quality of life, and up to 50% of patients have significant anxiety and/or depression. Often the distinction between dyspepsia and gastroparesis is based on clinical judgement rather than established criteria. Hyperglycemia, autonomic neuropathy, and enteric neuromuscular inflammation and injury are implicated in the pathogenesis of delayed GE. Alternatively, there are limited data to suggest that delayed GE may affect glycemic control. The management of diabetic gastroparesis is guided by the severity of symptoms, the magnitude of delayed GE, and the nutritional status. Initial options include dietary modifications, supplemental oral nutrition, and antiemetic and prokinetic medications. Patients with more severe symptoms may require a venting gastrostomy or jejunostomy and/or gastric electrical stimulation. Promising newer therapeutic approaches include ghrelin receptor agonists and selective 5-hydroxytryptamine receptor agonists.

Relationship between symptoms during a gastric emptying study and intestinal chemosensitivity with daily symptoms

BACKGROUND

Non-ulcer dyspepsia (NUD) is a heterogeneous disorder, which is characterized by upper gastrointestinal symptoms and sensorimotor disturbances, including abnormal gastric emptying (GE) and increased intestinal chemosensitivity, and associated with greater plasma glucagon-like peptide-1 (GLP-1) levels during duodenal lipid infusion. However, the relationship(s) between these disturbances and daily symptoms in NUD is variable. We hypothesize that abnormal GE and symptoms during a GE study and during duodenal lipid infusion are associated with the severity of daily symptoms and that GLP-1 mediates symptoms during duodenal lipid infusion in NUD.

METHODS

Gastric emptying of solids, symptoms during the GE study and duodenal lipid infusion, and daily gastrointestinal symptoms (2 week diary) were measured in 24 healthy controls and 40 NUD patients. During duodenal lipid infusion, participants received the GLP-1 antagonist exendin 9-39 or placebo.

KEY RESULTS

In controls and patients, GE of solids was normal in 75% and 75%, delayed in 8% and 12.5%, or rapid in 17% and 12.5%, respectively. No controls but 26 patients (65%) had severe symptoms during the GE study. During lipid infusion, gastrointestinal symptoms were greater (P = .001) in patients and not affected by exendin. Symptoms during GE study and lipid infusion accounted for respectively 62% and 37% of variance in daily symptom severity.

CONCLUSIONS

In NUD, symptoms during a GE study and to a lesser extent during lipid infusion explain the variance in daily symptoms. Intestinal chemosensitivity is not reduced by GLP-1 antagonist. Assessment of symptoms during a GE study may provide a useful biomarker for NUD in research and clinical practice.

Duodenal Chemosensing of Short-Chain Fatty Acids: Implications for GI Diseases

PURPOSE OF REVIEW

Short-chain fatty acids (SCFAs), the main bacterial fermentation products in the hindgut of hindgut fermenters, are also present in the foregut lumen. We discuss the impact of SCFAs in the duodenal defense mechanisms and in the gastrointestinal (GI) pathogenesis.

RECENT FINDINGS

Luminal SCFAs augment the duodenal mucosal defenses via release of serotonin (5-HT) and glucagon-like peptide-2 (GLP-2) from enteroendocrine cells. Released GLP-2 protects the small intestinal mucosa from nonsteroidal anti-inflammatory drug-induced enteropathy. SCFAs are also rapidly absorbed via SCFA transporters and interact with afferent and myenteric nerves. Excessive SCFA signals with 5-HT₃ receptor overactivation may be implicated in the pathogenesis of irritable bowel syndrome symptoms. SCFA production exhibits diurnal rhythms with host physiological responses, suggesting that oral SCFA treatment may adjust the GI clocks. SCFAs are not only a source of energy but also signaling molecules for the local regulation of the GI tract and systemic regulation via release of gut hormones. Targeting SCFA signals may be a novel therapeutic for GI diseases and metabolic syndrome.

GI Dysfunctions in Diabetic Gastroenteropathy, Their Relationships With Symptoms, and Effects of a GLP-1 Antagonist

CONTEXT

Delayed gastric emptying (GE) is common but often asymptomatic in diabetes. The relationship between symptoms, glycemia, and neurohormonal functions, including glucagonlike peptide 1 (GLP-1), are unclear.

OBJECTIVES

To assess whether GE disturbances, symptoms during a GE study, and symptoms during enteral lipid infusion explain daily symptoms and whether GLP-1 mediates symptoms during enteral lipid infusion.

DESIGN

In this randomized controlled trial, GE, enteral lipid infusion, gastrointestinal (GI) symptoms during these assessments, autonomic functions, glycosylated hemoglobin (HbA1c), and daily GI symptoms (2-week Gastroparesis Cardinal Symptom Index diary) were evaluated. During enteral lipid infusion, participants received the GLP-1 antagonist exendin 9-39 or placebo.

SETTING

Single tertiary referral center.

PARTICIPANTS

24 healthy controls and 40 patients with diabetic gastroenteropathy.

MAIN OUTCOME MEASURES

GE, symptoms during enteral lipid infusion, and the effect of exendin 9-39 on the latter.

RESULTS

In patients, GE was normal (55%), delayed (33%), or rapid (12%). During lipid infusion, GI symptoms tended to be greater (P = 0.06) in patients with diabetes mellitus (DM) than controls; exendin 9-39 did not affect symptoms. The HbA1c was inversely correlated with the mean symptom score during the GE study (r = -0.46, P = 0.003) and lipid infusion (r = -0.47, P < 0.01). GE and symptoms during GE study accounted for 40% and 32%, respectively, of the variance in daily symptom severity and quality of life.

CONCLUSIONS

In DM gastroenteropathy, GE and symptoms during a GE study explain daily symptoms. Symptoms during enteral lipid infusion were borderline increased but not reduced by a GLP-1 antagonist.

Recent understanding of the pathophysiology of functional dyspepsia: role of the duodenum as the pathogenic center

Over almost 30 years since functional dyspepsia (FD) was defined, researchers have endeavored to elucidate the pathophysiology of functional gastrointestinal disorders. Now a consensus is emerging that the gastric symptoms of FD are caused mainly by gastric motility abnormalities and gastric hypersensitivity. The involvement of other causative factors including acid, Helicobacter pylori, psychological factors, and diet has been debated, but how they are involved in the manifestation of dyspeptic symptoms remains unclear. We believe that most of those factors cause FD symptoms by inducing gastric motility abnormalities and gastric hypersensitivity via the duodenum. Here, we discuss 2 possible reasons why patients with FD experience chronic upper abdominal symptoms: (1) the possibility that the contents of the duodenum of patients with FD differ from those of healthy persons and the different contents stimulate the duodenum, and (2) the possibility that the duodenum of patients with FD is more sensitive to noxious stimuli because of low-grade inflammation and increased mucosal permeability.

Role of Gut Microbiota-Gut Hormone Axis in the Pathophysiology of Functional Gastrointestinal Disorders

Gut microbiota exert a pivotal influence on various functions including gastrointestinal (GI) motility, metabolism, nutrition, immunity, and the neuroendocrine system in the host. These effects are mediated by not only short-chain fatty acids produced by microbiota but also gut hormones and inflammatory signaling by enteroendocrine and immune cells under the influence of the microbiota. GI motility is orchestrated by the enteric nervous system and hormonal networks, and disturbance of GI motility plays an important role in the pathophysiology of functional gastrointestinal disorders (FGIDs). In this context, microbiota-associated mediators are considered to act on specific receptors, thus affecting the enteric nervous system and, subsequently, GI motility. Thus, the pathophysiology of FGIDs is based on alterations of the gut microbiota/gut hormone axis, which have crucial effects on GI motility.

Functional Dyspepsia: Advances in Diagnosis and Therapy

Functional dyspepsia (FD) is a common but under-recognized syndrome comprising bothersome recurrent postprandial fullness, early satiety, or epigastric pain/burning. Epidemiologically, there are two clinically distinct FD syndromes (although these often overlap clinically): postprandial distress syndrome (PDS; comprising early satiety or meal-related fullness) and epigastric pain syndrome. Symptoms of gastroesophageal reflux disease overlap with FD more than expected by chance; a subset has pathological acid reflux. The pre-test probability of FD in a patient who presents with classical FD symptoms and no alarm features is high, approximately 0.7. Coexistent heartburn should not lead to the exclusion of FD as a diagnosis. One of the most exciting observations in FD has been the consistent finding of increased duodenal eosinophilia, notably in PDS. Small bowel homing T cells, signaling intestinal inflammation, and increased cytokines have been detected in the circulation, and elevated tumor necrosis factor-α levels have been significantly correlated with increased anxiety. Postinfectious gastroenteritis is a risk factor for FD. Therapeutic options remain limited and provide only symptomatic benefit in most cases. Only one therapy is known to change the natural history of FD–Helicobacter pylori eradication. Treatment of duodenal eosinophilia is under investigation.

FFA2 activation combined with ulcerogenic COX inhibition induces duodenal mucosal injury via the 5-HT pathway in rats

Serotonin (5-HT), predominantly synthesized and released by enterochromaffin cells, is implicated in gastrointestinal symptoms such as emesis, abdominal pain, and diarrhea. Because luminal short-chain fatty acids (SCFAs) release 5-HT from enterochromaffin cells, which express the SCFA receptor free fatty acid receptor 2 (FFA2) in rat duodenum, we examined the effects of the selective FFA2 agonist phenylacetamide-1 (PA1) on duodenal 5-HT release with consequent bicarbonate secretion [duodenal bicarbonate secretion (DBS)] and on indomethacin (IND)-induced enteropathy. Intestinal injury was induced by IND (10 mg/kg sc) with or without PA1. We measured DBS in vivo in a duodenal loop perfused with PA1 while measuring 5-HT released in the portal vein. Duodenal blood flow was measured by laser-Doppler flowmetry. IND induced small intestinal ulcers with duodenal sparing. PA1 given with IND (IND + PA1) dose dependently induced duodenal erosions. IND + PA1-induced duodenal lesions were inhibited by the FFA2 antagonist GLPG-0974, ondansetron, or omeprazole but not by RS-23597 or atropine. Luminal perfusion of PA1 augmented DBS accompanied by increased portal blood 5-HT concentrations with approximately eight times more release at 0.1 mM than at 1 µM, with the effects inhibited by coperfusion of GLPG-0974. Luminal PA1 at 1 µM increased, but at 0.1 mM diminished, duodenal blood flow. Cosuperfusion of PA1 (0.1 mM) decreased acid-induced hyperemia, further reduced by IND pretreatment but restored by ondansetron. These results suggest that, although FFA2 activation enhances duodenal mucosal defenses, FFA2 overactivation during ulcerogenic cyclooxygenase inhibition may increase the vulnerability of the duodenal mucosa to gastric acid via excessive 5-HT release and 5-HT₃ receptor activation, implicated in foregut-related symptoms such as emesis and epigastralgia.NEW & NOTEWORTHY Luminal free fatty acid receptor 2 agonists stimulate enterochromaffin cells and release serotonin, which enhances mucosal defenses in rat duodenum. However, overdriving serotonin release with high luminal concentrations of free fatty acid 2 ligands such as short-chain fatty acids injures the mucosa by decreasing mucosal blood flow. These results are likely implicated in serotonin-related dyspeptic symptom generation because of small intestinal bacterial overgrowth, which is hypothesized to generate excess SCFAs in the foregut, overdriving serotonin release from enterochromaffin cells.

Nutrition and Hyperglycemia Management in the Inpatient Setting (Meals on Demand, Parenteral, or Enteral Nutrition)

PURPOSE OF REVIEW

The goal of this paper is to provide the latest evidence and expert recommendations for management of hospitalized patients with diabetes or hyperglycemia receiving enteral (EN), parenteral (PN) nutrition support or, those with unrestricted oral diet, consuming meals on demand.

RECENT FINDINGS

Patients with and without diabetes mellitus commonly develop hyperglycemia while receiving EN or PN support, placing them at increased risk of adverse outcomes, including in-hospital mortality. Very little new evidence is available in the form of randomized controlled trials (RCT) to guide the glycemic management of these patients. Reduction in the dextrose concentration within parenteral nutrition as well as selection of an enteral formula that diminishes the carbohydrate exposure to a patient receiving enteral nutrition are common strategies utilized in practice. No specific insulin regimen has been shown to be superior in the management of patients receiving EN or PN nutrition support. For those receiving oral nutrition, new challenges have been introduced with the most recent practice allowing patients to eat meals on demand, leading to extreme variability in carbohydrate exposure and risk of hypo and hyperglycemia. Synchronization of nutrition delivery with the astute use of intravenous or subcutaneous insulin therapy to match the physiologic action of insulin in patients receiving nutritional support should be implemented to improve glycemic control in hospitalized patients. Further RCTs are needed to evaluate glycemic and other clinical outcomes of patients receiving nutritional support. For patients eating meals on demand, development of hospital guidelines and policies are needed, ensuring optimization and coordination of meal insulin delivery in order to facilitate patient safety.

Energy-Dense Formulae May Slow Gastric Emptying in the Critically Ill

BACKGROUND

Enteral feed intolerance occurs frequently in critically ill patients and can be associated with adverse outcomes. "Energy-dense formulae" (ie, >1 kcal/mL) are often prescribed to critically ill patients to reduce administered volume and are presumed to maintain or increase calorie delivery. The aim of this study was to compare gastric emptying of standard and energy-dense formulae in critically ill patients.

METHODS

In a retrospective comparison of 2 studies, data were analyzed from 2 groups of patients that received a radiolabeled 100-mL "meal" containing either standard calories (1 kcal/mL) or concentrated calories (energy-dense formulae; 2 kcal/mL). Gastric emptying was measured using a scintigraphic technique. Radioisotope data were collected for 4 hours and gastric emptying quantified. Data are presented as mean ± SE or median [interquartile range] as appropriate.

RESULTS

Forty patients were studied (n = 18, energy-dense formulae; n = 22, standard). Groups were well matched in terms of demographics. However, patients in the energy-dense formula group were studied earlier in their intensive care unit admission (P = .02) and had a greater proportion requiring inotropes (P = .002). A similar amount of calories emptied out of the stomach per unit time (P = .57), but in patients receiving energy-dense formulae, a greater volume of meal was retained in the stomach (P = .045), consistent with slower gastric emptying.

CONCLUSIONS

In critically ill patients, the administration of the same volume of a concentrated enteral nutrition formula may not result in the delivery of more calories to the small intestine over time because gastric emptying is slowed.

Validating endpoints for therapeutic trials in fecal incontinence

BACKGROUND

A 50% or greater reduction in the frequency of fecal incontinence (FI) recorded with daily bowel diaries is the primary endpoint in clinical trials of FI. Whether this difference is clinically important is unknown. The relationship between FI symptoms recorded with daily and weekly instruments is unknown. The contribution of psychological factors to quality of life (QOL) in FI is unclear.

METHODS

Fecal incontinence severity was assessed with daily bowel diaries and periodic questionnaires (fecal incontinence severity score [FISS], FIQOL, 36-Item Short Form Health Survey [SF-36], and hospital anxiety and depression scales) for 4 weeks before and during double-blind randomization to placebo or clonidine in 44 women with FI. The reduction in FI frequency was compared to the minimal clinically important difference (MCID) computed from the FISS. Endpoints of FI were compared between daily and weekly diaries.

KEY RESULTS

The FISS exceeded the MCID in 75% and 83% of patients in whom the FI frequency declined by 50-74% and ≥75% respectively. Parameters of FI measured with daily and weekly instruments were significantly correlated. The daily parameters explained 71% of the inter-patient variation in the FISS. The SF-36 health scores, rather than the FISS rating, explained a majority of the inter-subject variation in FIQOL.

CONCLUSIONS & INFERENCES

Most patients who report a ≥50% reduction in FI frequency experience a clinically important improvement. Weekly questionnaires accurately assess the severity of FI. Self-reported physical and mental health explained a greater proportion of the variance in FIQOL than FI symptom severity.

Functional Dyspepsia and Gastroparesis

BACKGROUND

Upper gastrointestinal disorders typically present with common symptoms. The most relevant non-mucosal diseases are gastroparesis, functional dyspepsia and rumination syndrome. The literature pertaining to these 3 conditions was reviewed.

KEY MESSAGES

Gastroparesis is characterized by delayed gastric emptying in the absence of mechanical obstruction of the stomach. The cardinal symptoms include postprandial fullness (early satiety), nausea, vomiting and bloating. The most frequently encountered causes of these symptoms are mechanical obstruction (pyloric stenosis), iatrogenic disease, gastroparesis, functional dyspepsia, cyclical vomiting and rumination syndrome. The most common causes of gastroparesis are neuropathic disorders such as diabetes, idiopathic, post-vagotomy and scleroderma among myopathic disorders. Principles of management of gastroparesis include exclusion of mechanical obstruction with imaging and iatrogenic causes with careful medication and past surgical history. Prokinetics and anti-emetics are the mainstays of treatment. Functional dyspepsia is characterized by the same symptoms as gastroparesis; in addition to delayed gastric emptying, pathophysiological abnormalities include accelerated gastric emptying, impaired gastric accommodation and gastric or duodenal hypersensitivity to distension and nutrients. Novel treatments include tricyclic antidepressants in patients with normal gastric emptying, acotiamide (acetyl cholinesterase inhibitor) and 5-HT1A receptor agonists such as buspirone. Rumination syndrome is characterized by repetitive regurgitation of gastric contents occurring within minutes after a meal. Episodes often persist for 1-2 h after the meal, and the regurgitant consists of partially digested food that is recognizable in its taste. Regurgitation is typically effortless or preceded by a sensation of belching. This has been summarized as a 'meal in, meal out, day in, day out' behavior for weeks or months, differentiating rumination from gastroparesis. Patients often have a background of psychological disorder or a prior eating disorder. Treatment is based on behavioral modification.

CONCLUSION

Precise identification of the cause and pathophysiology of upper gastrointestinal symptoms is essential for optimal management.

Managing hyperglycemia and diabetes in patients receiving enteral feedings: A health system approach

Evidence of poor outcomes in hospitalized patients with hyperglycemia has led to new and revised guidelines for inpatient management of diabetes. As providers become more aware of the need for better blood glucose control, they are finding limited guidance in the management of patients receiving enteral nutrition. To address the lack of guidelines in this population, Duke University Health System has developed a consistent practice for managing such patients. Here, we present our practice strategies for insulin use in patients receiving enteral nutrition. Essential factors include assessing the patients' history of diabetes, hyperglycemia, or hypoglycemia and timing and type of feedings. Insulin practices are then designed to address these issues keeping in mind patient safety in the event of abrupt cessation of nutrition. The outcome of the process is a consistent and safe method for glucose control with enteral nutrition.