S. Vigneri

Functional Heartburn has more in common with Functional Dyspepsia than with Non-Erosive Reflux Disease

Introduction: Functional dyspepsia and non-erosive reflux disease (NERD) are prevalent gastrointestinal conditions with accumulating evidence regarding an overlap between the two. Still, patients with NERD represent a very heterogeneous group and limited data on dyspeptic symptoms in various subgroups of NERD are available. Aim: To evaluate the prevalence of dyspeptic symptoms in patients with NERD subclassified by using 24 h impedance-pH monitoring (MII-pH). Methods: Patients with typical reflux symptoms and normal endoscopy underwent impedance-pH monitoring off proton pump inhibitor treatment. Oesophageal acid exposure time (AET), type of acid and non-acid reflux episodes, and symptom association probability (SAP) were calculated. A validated dyspepsia questionnaire was used to quantify dyspeptic symptoms prior to reflux monitoring. Results: Of 200 patients with NERD (105 female; median age, 48 years), 81 (41%) had an abnormal oesophageal AET (NERD pH-POS), 65 (32%) had normal oesophageal AET and positive SAP for acid and/or non-acid reflux (hypersensitive oesophagus), and 54 (27%) had normal oesophageal AET and negative SAP (functional heartburn). Patients with functional heartburn had more frequent (p<0.01) postprandial fullness, bloating, early satiety and nausea compared to patients with NERD pH-POS and hypersensitive oesophagus. Conclusion: The increased prevalence of dyspeptic symptoms in patients with functional heartburn reinforces the concept that functional gastrointestinal disorders extend beyond the boundaries suggested by the anatomical location of symptoms. This should be regarded as a further argument to test patients with symptoms of gastro-oesophageal reflux disease in order to separate patients with functional heartburn from patients with NERD in whom symptoms are associated with gastro-oesophageal reflux.

The 13C urea breath test in the diagnosis of Helicobacter pylori infection

The urea breath test (UBT) is one of the most important non-invasive methods for detecting Helicobacter pylori infection. The test exploits the hydrolysis of orally administered urea by the enzyme urease, which H pylori produces in large quantities. Urea is hydrolysed to ammonia and carbon dioxide, which diffuses into the blood and is excreted by the lungs. Isotopically labelled CO2 can be detected in breath using various methods. Labelling urea with 13C is becoming increasingly popular because this non-radioactive isotope is innocuous and can be safely used in children and women of childbearing age. Breath samples can also be sent by post or courier to remote analysis centres. The test is easy to perform and can be repeated as often as required in the same patient. A meal must be given to increase the contact time between the tracer and the H pylori urease inside the stomach. The test has been simplified to the point that two breath samples collected before and 30 minutes after the ingestion of urea in a liquid form suffice to provide reliable diagnostic information. The cost of producing 13C-urea is high, but it may be possible to reduce the dosage further by administering it in capsule form. An isotope ratio mass spectrometer (IRMS) is generally used to measure 13C enrichment in breath samples, but this machine is expensive. In order to reduce this cost, new and cheaper equipment based on non-dispersive, isotope selective, infrared spectroscopy (NDIRS) and laser assisted ratio analysis (LARA) have recently been developed. These are valid alternatives to IRMS although they cannot process the same large number of breath samples simultaneously. These promising advances will certainly promote the wider use of the 13C-UBT, which is especially useful for epidemiological studies in children and adults, for screening patients before endoscopy, and for assessing the efficacy of eradication regimens.

An evaluation of the antireflux properties of sodium alginate by means of combined multichannel intraluminal impedance and pH-metry

Background : Alginate‐based preparations act as mechanical antireflux barrier, which can reduce both acid and non‐acid reflux events and limit the proximal migration of oesophageal refluxate.

Functional and neurochemical changes of the gastrointestinal tract in a rodent model of Parkinson's disease.

Patients with Parkinsons disease develop motor disturbances often accompanied by peripheral autonomic dysfunctions, including gastrointestinal disorders, such as dysphagia, gastric stasis and constipation. While the mechanisms subserving enteric autonomic dysfunctions are not clearly understood, they may involve the enteric dopaminergic and/or nitrergic systems. In the present study, we demonstrate that rats with unilateral 6-hydroxydopamine lesion of nigrostriatal dopaminergic neurons develop a marked inhibition of propulsive activity compared to sham-operated controls, as indicated by a 60% reduction of daily fecal output at the 4th week of observation. Immunohistochemical data revealed that 6-hydroxydopamine treatment did not affect the total number of HuC/D-positive myenteric neurons in both the proximal and distal segments of ileum and colon. Conversely, in the distal ileum and proximal colon the number of nitrergic neurons was significantly reduced. These results suggest that a disturbed distal gut transit, reminiscent of constipation in the clinical setting, may occur as a consequence of a reduced propulsive motility, likely due to an impairment of a nitric oxide-mediated descending inhibition during peristalsis.

Cyclical changes of cortical excitability and metaplasticity in migraine: evidence from a repetitive transcranial magnetic stimulation study.

Summary Insight is provided into the pathophysiological mechanisms underlying the abnormal regulation of cortical function and its periodicity in episodic and chronic migraine. ABSTRACT The primary brain dysfunctions leading to the onset of a migraine attack remain largely unknown. Other important open questions concern the mechanisms of initiation, continuation, and termination of migraine pain, and the changes in brain function underlying migraine transformation. Brief trains of high‐frequency repetitive transcranial magnetic stimulation (rTMS), when applied to the primary motor cortex at suprathreshold intensity (≥120% of resting motor threshold [RMT]), elicit in healthy subjects a progressive, glutamate‐dependent facilitation of the motor evoked potentials (MEP). Conversely, in conditions of increased cortical excitability, the rTMS trains induce inhibitory MEP responses likely mediated by cortical homeostatic mechanisms. We enrolled 66 migraine‐without‐aura patients, 48 migraine‐with‐aura patients, 14 patients affected by chronic migraine (CM), and 20 healthy controls. We assessed motor cortical response to 5‐Hz rTMS trains of 10 stimuli given at 120% RMT. Patients with episodic migraine were studied in different phases of the migraine cycle: interictal, preictal, ictal, and postictal states. Results showed a facilitatory MEP response during the trains in patients evaluated in the preictal phase, whereas inhibitory responses were observed during and after a migraine attack, as well as in CM patients. In the interictal phase, different responses were observed, depending on attack frequency: facilitation in patients with low and inhibition in those with high attack recurrence. Our findings suggest that changes in cortical excitability and fluctuations in the threshold for inhibitory metaplasticity underlie the migraine attack recurrence, and could be involved in the process of migraine transformation.

Abnormal facilitatory mechanisms in motor cortex of migraine with aura

Experimental evidence suggests impairment of inhibitory intracortical circuits in migraine, while not much is known about activity of facilitatory intracortical circuits. In the present work we evaluated the effects of high frequency‐repetitive transcranial magnetic stimulation (hf‐rTMS) on the activity of facilitatory circuits of motor cortex in 18 patients affected by migraine with aura and 18 healthy subjects. Trains of 10 stimuli were applied to the motor cortex at 5‐Hz frequency with recording of the EMG traces from the contralateral abductor pollicis brevis muscle (APB). Two intensities of stimulation (110% and 130% of resting motor threshold) were used in order to explore whether motor cortex excitability was differently modulated. Twelve patients underwent hf‐rTMS both before and during prophylactic treatment with levetiracetam. Results showed that rTMS delivered at 110% intensity of stimulation at rest had a facilitatory effect on MEP size in untreated patients, while left MEP unchanged in controls. Conversely, when rTMS was applied at 130%, we observed MEP potentiation in healthy subjects and paradoxical MEP inhibition in migraineurs. In treated patients, levetiracetam inhibited MEP size at both 110% and 130% intensity of stimulation. Our findings reveal an opposite response of migraine motor cortex to 5‐Hz rTMS when it is delivered at different stimulation intensities, providing evidence of both hyper‐responsivity and self‐limiting hyperexcitability capacity, in line with studies supporting the concept that under conditions of cortical hyperexcitability inhibitory mechanisms of homeostatic plasticity could be activated.

Helicobacter pylori infection is not involved in the pathogenesis of either erosive or non‐erosive gastro‐oesophageal reflux disease

Background : The majority of reflux patients have non‐erosive reflux disease.

Comparison of the main oesophageal pathophysiological characteristics between short- and long-segment Barrett's oesophagus.

To assess the oesophageal manometric characteristics and 24‐h pH profiles of patients with both short‐segment and long‐segment Barretts oesophagus and compare them with those of patients with reflux oesophagitis and controls.

Clinical pharmacology and safety profile of esomeprazole, the first enantiomerically pure proton pump inhibitor.

Awareness of important differences in the pharmacological profile of individual optical isomers of chiral drugs led to the development of esomeprazole, the S-isomer of omeprazole, a new pharmacological entity designed to improve the clinical outcome of available proton pump inhibitors in the management of acid-related disorders. The superior acid control achieved by esomeprazole is mainly due to an advantageous metabolism compared with racemate omeprazole, leading to improved bioavailability and to enhanced delivery of the drug to the gastric proton pump.

Transcranial direct current stimulation preconditioning modulates the effect of high-frequency repetitive transcranial magnetic stimulation in the human motor cortex

Experimental studies emphasize the importance of homeostatic plasticity as a mean of stabilizing the properties of neural circuits. In the present work we combined two techniques able to produce short‐term (5‐Hz repetitive transcranial magnetic stimulation, rTMS) and long‐term (transcranial direct current stimulation, tDCS) effects on corticospinal excitability to evaluate whether and how the effects of 5‐Hz rTMS can be tuned by tDCS preconditioning. Twelve healthy subjects participated in the study. Brief trains of 5‐Hz rTMS were applied to the primary motor cortex at an intensity of 120% of the resting motor threshold, with recording of the electromyograph traces evoked by each stimulus of the train from the contralateral abductor pollicis brevis muscle. This interventional protocol was preconditioned by 15 min of anodal or cathodal tDCS delivered at 1.5 mA intensity. Our results showed that motor‐evoked potentials (MEPs) increased significantly in size during trains of 5‐Hz rTMS in the absence of tDCS preconditioning. After facilitatory preconditioning with anodal tDCS, 5‐Hz rTMS failed to produce progressive MEP facilitation. Conversely, when 5‐Hz rTMS was preceded by inhibitory cathodal tDCS, MEP facilitation was not abolished. These findings may give insight into the mechanisms of homeostatic plasticity in the human cerebral cortex, suggesting also more suitable applications of tDCS in a clinical setting.