Secondary heat hyperalgesia induced by melittin in humans.

Melittin, which is a principal protein of honeybee venom, can induce mechanical hyperalgesia in humans. The characteristics of the melittin induced mechanical hyperalgesia are quantitatively and qualitatively different from those evoked by capsaicin. The aim of the present study was to investigate in detail secondary heat hyperalgesia induced by melittin in humans.

An experimental study of viscero-visceral hyperalgesia using an ultrasound-based multimodal sensory testing approach.

Widespread visceral hypersensitivity and the overlap of symptom complexes observed in functional gastrointestinal disorders may be related to central sensitization and neuroplastic changes. A multimodal and multi-segmental model was developed to evaluate viscero-visceral hyperalgesia induced by experimental esophageal sensitization in healthy volunteers. Twelve healthy subjects were studied using a double-blinded, placebo-controlled design.

Gender differences in pain and biomechanical responses after acid sensitization of the human esophagus.

Our aims were to investigate gender differences to multimodal stimulations of the esophagus after experimentally induced sensitization. Thirty healthy age-matched subjects, 13 males and 17 females, were included. Pain evoked by mechanical and thermal stimuli was assessed before and after perfusion of the lower esophagus with 0.

Magnetic resonance imaging of the small bowel in Crohn's disease.

Objective: There may be advantages in using magnetic resonance imaging (MRI) in small-bowel disease. The aims of this study were to optimize the MRI examination technique and to evaluate the capabilities of MRI compared with those of conventional enteroclysis (CE).

Materials And Methods: MRI and CE were performed in 36 patients suspected of Crohn's disease.

[What is gallstone pain?].

This paper reviews our current understanding of the clinical symptoms and pain mechanisms in patients with gallstone disease. Although most patients have classical pain attacks, the pain localisation can be atypical due to convergence phenomena between somatic and visceral afferents. Furthermore, central neuroplastic changes induced by the recurrent pain attacks are probably of major importance for our understanding of the clinical symptoms.

Somatosensory changes in the referred pain area in patients with cholecystolithiasis.

Background And Aims: Patients with abdominal pain provoked by acute cholecystitis increase the somatic sensitivity in the referred somatic pain area. Our aim in the present paper was to examine somatosensory changes in the referred pain area (previously evoked by painful attacks) in patients with uncomplicated gallstone disease and to evaluate the possible relation between referred pain patterns and clinical findings. Somatosensory changes in these areas may be important in the persistent pain after treatment and may help to develop treatment strategies for abdominal pain in the post-cholecystectomy syndrome.

Statistical modeling of the response characteristics of mechanosensitive stimuli in the human esophagus.

Unlabelled: It is believed that mechanical stimuli of the human gut activate afferents responding to either noxious or normal, physiologic stimuli. They might be able to sensitize without relation to the contractile state of the smooth muscle. The current study aimed to verify the above characteristics by using a statistical model based on correlation analysis.

Cortical neuroplastic changes to painful colon stimulation in patients with irritable bowel syndrome.

The aim of this study was to model the cerebral generators following painful electrical stimulation of the sigmoid colon in 10 healthy controls and 10 patients with visceral pain due to the irritable bowel syndrome. The evoked brain potentials to 30 painful electrical stimuli from the sigmoid colon were recorded from 31 surface electrodes and subjected to electrical dipole source modelling. Two dipoles in the bilateral insular cortex, one dipole in the anterior cingulate gyrus and two dipoles in the bilateral second somatosensory area were found.

Experimental human pain models: a review of standardised methods for preclinical testing of analgesics.

Treatment of pain is one of the major challenges in clinical medicine. However, it is often difficult to evaluate the effect of a treatment, as the many symptoms of the underlying diseases often confound this assessment. Furthermore, as the pain mechanisms in many diseases are poorly understood, the limited successful trial and error approach is most often used in the selection of analgesics.

Differences between male and female responses to painful thermal and mechanical stimulation of the human esophagus.

It is uncertain to what degree sensation and pain relating to the gut are influenced by sex. The aim of the study was to explore sex differences to experimental multimodal stimulation of the esophagus in 22 age-matched males and females. A probe was positioned in the lower part of the esophagus.

Visceral pain: gender differences in response to experimental and clinical pain.

Gender differences in response to visceral pain have important implications for experimental studies and when evaluating clinical pain. Few studies have in details explored specific gender differences in response to experimental stimulation of selected visceral organs or specific visceral diseases. Lower pain threshold to e.

Cold and heat pain assessment of the human oesophagus after experimental sensitisation with acid.

The aim of the present study was to investigate the effect of thermal stimulation of the oesophagus before and after sensitisation with acid. In 17 healthy subjects a stimulation bag was used to re-circulate water at 5 and 60 degrees C for up to 90 s in the lower part of the oesophagus. The area under the temperature curve was used to assess the caloric load.

Dipolar source modelling of brain potentials evoked by painful electrical stimulation of the human sigmoid colon.

The aim of the study was to compare the cerebral generators following painful stimulation of the sigmoid colon and the abdominal skin in 11 healthy subjects. The evoked potentials (EPs) were recorded from 31 surface electrodes following painful electrical stimuli of the sigmoid colon, and of the referred pain area on the abdomen. Current dipole models estimating the EPs amplitude and topography were calculated.

Multi-modal induction and assessment of allodynia and hyperalgesia in the human oesophagus.

Background And Aims: Experimental pain models based on single stimuli have to some degree limited visceral pain studies in humans. Hence, the aim of this study was to investigate the effect of multi-modal visceral pain stimuli of the oesophagus in healthy subjects before and after induction of visceral hyperalgesia. We used a multi-modal psychophysical assessment regime and a neurophysiological method (nociceptive reflex) for the characterisation of the experimentally induced hyperalgesia.

Pain intensity and biomechanical responses during ramp-controlled distension of the human rectum.

The current study aimed to refine the conventional distension model in the human rectum by measuring the cross-sectional area with a ramp-controlled impedance planimetric system. After preconditioning, the rectum in seven volunteers was distended 56 times with infusion rates of 50, 100 and 200 ml/min and at 100 ml/min during relaxation of the smooth muscle with glucagon. The pump was reversed at maximal tolerated pain.

Gut pain and hyperalgesia induced by capsaicin: a human experimental model.

Human experimental visceral pain models using chemical stimulation are needed for the study of visceral hyperexcitability. Our aim was to stimulate the human gut with chemical activators (capsaicin, glycerol) and measure quantitatively the induced hyperexcitability to painful mechanical gut distension. Ten otherwise healthy subjects with an ileostoma participated.

Pain and biomechanical responses to distention of the duodenum in patients with systemic sclerosis.

Background & Aims: Abnormalities of the small intestine have been indicated in systemic sclerosis. The aim was to use a new method to study the active-passive mechanical and sensory properties of the duodenum in these patients.

Methods: A volume-controlled ramp-distention protocol was used in the duodenum in 9 patients and 8 healthy controls.

Short latency cerebral response evoked by painful electrical stimulation applied to the human sigmoid colon and to the convergent referred somatic pain area.

Background. The brain-gut interaction is important for the understanding of pain mechanisms related to gastroenterological diseases. Unfortunately little is known about the early cerebral events related to the processing of gut-evoked pain.

Induction of non-painful and painful intestinal sensations by hypertonic saline: a new human experimental model.

Background And Aims: To develop a pain model for chemical stimulation of the human gut.

Methods: In a double-blind experimental study 10 subjects with a previously performed sigmoidostomy were randomised to receive injections with either isotonic or hypertonic saline in the colonic mucosa. In the hypertonic experimental arm, 0.

Sensory and biomechanical responses to ramp-controlled distension of the human duodenum.

The aim of this study was to develop a new method for investigation of the relationship among the mechanical stimulus, the biomechanical properties, and the visceral perception evoked by volume/ramp-controlled distension in the human duodenum in vivo. An impedance planimetric probe for balloon distension was placed in the third part of the duodenum in seven healthy volunteers. Distension of the duodenum was done at infusion rates of 10, 25, and 50 ml/min.

Controlled dilatation of the uterine cervix--an experimental visceral pain model.

Pain originating from the female reproductive organs is a substantial clinical problem to treat. Experimental models may be a tool for the study of visceral pain mechanisms and hence provide information to aid in formulating new treatment strategies. The aim was to develop and evaluate the performance and safety of a model for nociceptive stimulation of the uterine cervix by balloon dilatation using impedance planimetry.

Somatosensory changes in the referred pain area following acute inflammation of the appendix.

Background And Aims: Abdominal pain provoked by acute gastrointestinal disease may increase the sensitivity in the referred somatic pain area. The aim of this study was to examine sensory changes in the referred pain area during acute appendicitis.

Subjects: Twenty patients with clinical symptoms of appendicitis were included; 16 of these had appendicitis confirmed at operation.

Multimodal assessment of pain in the esophagus: a new experimental model.

A new multimodal pain assessment model was developed integrating electrical, mechanical, cold, and warmth stimuli into the same device. The device, with a bag and electrodes for electrical stimulation, was positioned in the lower part of the esophagus in 11 healthy subjects. Mechanical stimuli were delivered with an impedance planimetric system.