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Biomedical subjects

M Delvaux

Publications and source records attributed to M Delvaux.

At least 55 records · Page 3Linked to original sources
PubMed1999

Principles of applied neurogastroenterology: physiology/motility-sensation.

Many of the symptoms characteristic of the functional gastrointestinal disorders (FGID) are consistent with dysfunction of the motor and/or sensory apparatus of the digestive tract. Those aspects of sensorimotor dysfunction most relevant to the FGID include alterations in: gut contractile activity; myoelectrical activity; tone and compliance; and transit, as well as an enhanced sensitivity to distension, in each region of the gastrointestinal tract. Assessment of these phenomena involves a number of techniques, some well established and others requiring further validation. Using such techniques, researchers have reported a wide range of alterations in sensory and in motor function in the FGID. Importantly, however, relationships between such dysfunction and symptoms have been relatively weak, and so the clinical relevance of the former remains unclear. Moreover, the proportions of patients in the various symptom subgroups who display dysfunction, and the extent and severity of their symptoms, require better characterization. On a positive note, progress is occurring on several fronts, especially in relation to functional dyspepsia and irritable bowel syndrome, and based on the data gathered to date, a number of areas where further advances are required can be highlighted.

Colonic Diseases, Functional↗
PubMed1999

A European approach to irritable bowel syndrome management.

Irritable bowel syndrome (IBS) is characterized by a number of clinical features and probably comprises a cluster of different conditions. The most frequent symptom reported by IBS patients is abdominal pain, although for a number of patients, bowel disturbances are the most prominent symptoms. Diarrhetic patients are seen in referral centres in continental Europe less frequently than in the United Kingdom or the United States. On the contrary, patients with constipation-prone IBS may comprise up to 80% of the IBS population referred to these centres. The pathophysiology of IBS is based on multiple factors. Most of the therapeutics proposed for the management of patients with IBS have been developed on the assumption that motility disorders of the gut are the most reliable pathological findings among these patients. Consequently, antispasmodics and motility regulatory agents have been widely used, alone or in association with intestinal adsorbents (clay-derived preparations), and laxatives or antidiarrhetic agents. Most of these drugs were developed several decades ago, and studies showing their efficacy have not reached the level of quality that is now required of randomized controlled trials. Therefore, following a complete and detailed review published in 1989, these drugs have not been used extensively in the United Kingdom or the United States. Large inquiries have also shown that the duration of prescription is quite different among countries. In European countries, maintenance therapy is frequently prescribed for several weeks to attempt to decrease the number of acute episodes. In contrast, psychotropic drugs are less popular among European gastroenterologists than among American gastroenterologists. However, multidisciplinary approaches to the treatment of these patients are frequent, and such drugs are often prescribed by home physicians. The results of large surveys estimated the yearly cost of such treatments to be around US$850. Patients with constipation and elderly patients with chronic disease receive more expensive treatments.

Abdominal Pain↗
PubMed1998

Effect of hepatic impairment on the pharmacokinetics of zolmitriptan.

Zolmitriptan, an oral 5HT1D agonist for the acute treatment of migraine, is cleared from the systemic circulation mainly by hepatic metabolism. Consequently, changes in hepatic function may result in changes in the pharmacokinetics of zolmitriptan. This open, parallel-group study was conducted to compare the pharmacokinetics and tolerability of a single 10-mg dose of zolmitriptan in healthy subjects and patients with hepatic impairment. A total of 37 participants entered and completed the study, including 10 healthy volunteers, 11 patients with moderate hepatic impairment, 10 patients with severe hepatic impairment without ascites, and 6 patients with severe hepatic impairment with ascites. The metabolism of zolmitriptan was reduced in patients with severe hepatic impairment compared with healthy subjects, resulting in higher peak plasma concentrations (47%), increased exposure (226%), and prolonged half-life (157%). The changes were similar in the presence and absence of ascites. Smaller changes were observed in patients with moderate hepatic impairment. Plasma concentrations of the three major metabolites of zolmitriptan were reduced in the patients with hepatic impairment. Patients with moderate hepatic impairment require no dosage adjustment, but the recommended daily intake of zolmitriptan may need to be reduced in patients with severe hepatic impairment.

Adult↗
PubMed1998

Structured reporting in gastrointestinal endoscopy: integration with DICOM and minimal standard terminology.

The interest of the international gastrointestinal endoscopy community in developing standards for endoscopic reporting resulted in a standard lexicon for describing endoscopic findings. It became clear that in order to facilitate the widespread use of this lexicon, a messaging standard which could link images to text had to be adopted. The DICOM 3.0 Standard (digital imaging and communication in medicine) was extended by the introduction of the Visible Light Supplement and the SNOMED-DICOM microglossary. These two standards should expand the ability of DICOM to accommodate endoscopic images and the clinical description of these images.

Computer Communication Networks↗
PubMed1998

The minimal standard terminology for digestive endoscopy: introduction to structured reporting.

The wider use of computers for the management of endoscopic data and the use of electronic endoscopes for the production of high quality endoscopic images has made the standardization of terminology and images formats necessary in digestive endoscopy reports. The European Society for Gastrointestinal Endoscopy and the American Society for Gastrointestinal Endoscopy have combined their efforts to propose a Minimal Standard Terminology for Computerized Databases in Endoscopy. This terminology is based on the following principles: no term describing findings less frequent than 1%, of the daily practice, and no term based on subjective impressions. The Minimal Standard Terminology has been developed according to the natural process of constructing an endoscopic report in natural language and deals with the following: reasons for performing the examination, endoscopic findings, endoscopic diagnosis, additional therapeutic and diagnosis procedures (biopsies, etc.). It is subdivided according to the main organs examined with an endoscopy. Until now, the Minimal Standard Terminology was tested in many centers and was shown to accurately cover 95% of routine examinations for the upper gastrointestinal tract, colonoscopy and cholangio-pancreatography. It is currently being tested in an a prospective way in several centers in Europe (with a grant from the European Commission DGXIII-C4) and in the USA (with grant from the AHDHF).

Endoscopy, Digestive System↗
PubMed1998

Effect of alosetron on responses to colonic distension in patients with irritable bowel syndrome.

BACKGROUND: Visceral hypersensitivity plays a major role in the pathophysiology of irritable bowel syndrome, as shown by balloon distension studies. 5-HT3 receptors on afferent nerves may modulate visceral sensitivity and be the target of new treatments for irritable bowel syndrome. AIM: To evaluate the effects of alosetron, a potent and selective 5-HT3 antagonist, on the perception of colonic distension by patients with irritable bowel syndrome, and on the colonic compliance to distension with a barostat. METHODS: Twenty-five irritable bowel syndrome patients were included in a randomized double-blind parallel group trial; data were available for 22 (Rome criteria; 48 +/- 11 years: 13 men and nine women). Patients were treated for 7 days with placebo (n = 6), alosetron 0.25 mg b.d. (n = 8) or alosetron 4 mg b.d. (n = 8). On day 6, a barostat bag was placed in the left colon. On day 7, after an overnight fast, isobaric phasic distensions were performed (4 mmHg steps, 5 min) up to the step triggering a sensation of abdominal pain. RESULTS: Groups were comparable at inclusion (age, sex, symptoms, bowel habits). There were no differences between treatment groups in pressure recorded within the bag at the time of first sensation of abdominal pain. However, bag volumes were significantly increased. At the first sensation threshold, median volume differences of 61 mL and 90 mL (P = 0.028) were recorded with alosetron 0.25 mg b.d. and 4 mg b.d., respectively. At the threshold of abdominal pain, these differences were 71 mL (P = 0.039) and 84 mL (P = 0.017). Colonic compliance increased from 5.9 mL/mmHg on placebo to 7.6 mL/mmHg on alosetron 0.25 mg b.d. and to 9.8 mL/mmHg (P = 0.034) on alosetron 4 mg b.d. CONCLUSION: Alosetron increases the compliance of the colon to distension, and could thereby contribute to changes in perception of colonic distension and improvement in the symptoms of irritable bowel syndrome.

Adult↗
PubMed1998

Correlation of desensitisation of platelet activating factor (PAF) receptors with intensity of inflammation and intestinal PAF content during experimental ileitis in guinea pig.

AIM: To determine the kinetics of platelet activating factor (PAF) and prostaglandin E2 (PGE2) receptor desensitisation during intestinal inflammation induced by trinitrobenzenesulphonic acid (TNB) instillation and to study the relation between receptor regulation, inflammatory lesions, and PAF content of the gut wall. METHODS: Receptor desensitisation was assessed on isolated smooth muscle cells from the circular layer. PAF content of the intestinal wall was determined by thin layer chromatography and radioimmunoassay. RESULTS: After an acute inflammatory phase on day 1, subacute changes appeared in TNB instilled ileum, with a maximal intensity on day 6. In control animals, PAF 10 nM and PGE2 10 nM provoked a maximal contraction in the range of 24% of cell shortening. On days 1 and 3 after intestinal instillation of TNB, PAF induced contraction was not altered whereas the effect of PGE2 was progressively desensitised (2 logM rightward shift of its concentration-response curve: Cmax = 1 microM; p < 0.01). Between days 4 and 6, the concentration-response curve of PGE2 shifted by only 1 logM (p < 0.05) whereas the curve of PAF induced contraction shifted by 2 logM (Cmax = 1 microM; p < 0.01). The PAF content of the ileal wall was maximal between days 3 and 5 (300 ng/mg tissue). On days 10 and 15, PAF and PGE2 induced contractions were similar to those observed on day 1, and PAF content returned to basal. CONCLUSION: Inflammation induced by TNB instillation triggers PAF and PGE2 receptor desensitisation; this is dependent on the duration of inflammation and correlates with PAF content in the ileum. This receptor desensitisation may play a protective role by preventing overstimulation of intestinal smooth muscle cells.

Acetylcholine↗
PubMed1998

[Tetany, spasmophilia, hyperventilation syndrome: theoretical and therapeutic synthesis].

The hyperventilation syndrome (HVS), characterised by multiple somatic symptoms induced by inappropriate hyperventilation, constitutes the physiopathological manifestation of a common disorder in general medicine. As a synonym of spasmophilia or tetany, it has the advantage of offering diagnostic criteria, even though the latter are still vaguely defined. But its definition allows for objective measurements: indeed, a decrease in PCO2 during a hyperventilation provoking test and an abnormally low PCO2 rate at rest can be easily quantified. Moreover, the HVS concept offers a treatment which is both structured (respiratory reeducation, psychotherapy and pharmacology) and efficient. Yet, a number of scientific uncertainties still exist. There is no general agreement regarding the criteria which should be taken into account in a hyperventilation provoking test in order to diagnose an hyperventilation syndrome; the specificity of such a test is weak and a placebo can induce as many symptoms as can a HVS. Respiratory reeducation has good results but does not necessarily have an effect on PCO2. Some therapists see in it no more than a mechanism of relaxation and a rational explanation of frightening symptoms. This has led some authors to reject the term "hyperventilation syndrome" and to prefer the expression "chronic hyperventilation of unknown origin".

Carbon Dioxide↗
PubMed1998

Role of vasoactive intestinal polypeptide in the adaptation of intestinal smooth muscle cells to mechanical distension.

Distension of the small intestine can play a role in the pathogenesis of various functional intestinal disorders. This study determined the role of vasoactive intestinal polypeptide (VIP) in the adaptative response of intestinal smooth muscle to acute and chronic distension of the ileum in vivo. Several in vitro experiments were performed to identify the mechanism of receptor regulation. Distension was applied by a balloon inflated with air in the ileum either during a single episode in anesthetized or repeatedly in conscious guinea pigs. Then, muscle cells were isolated by enzymatic digestion from the distended and nondistended adjacent ileal segments. In addition, in vitro experiments were performed on freshly dispersed cells for determination of mechanisms. Control cells maximally relaxed (Cmax) at 1 microM VIP (EC50 = 50 pM) and 100 microM isoproterenol (EC50 = 7 nM). Both acute and chronic distensions triggered a right-ward shift of the concentration-response curves for VIP (Cmax = 100 microM, EC50 = 10 nM). A desensitization of the relaxing effect of VIP receptors was also observed when cells were preincubated for 30 min in vitro with VIP. By contrast, the relaxing effect of isoproterenol was affected neither by in vivo distension nor by in vitro incubation with isoproterenol. Desensitization of VIP receptors was prevented by in vitro incubation of cells with VIP plus a VIP antagonist [(D-P-Cl-Phe6,Leu17)VIP] and by intraluminal perfusion of the VIP antagonist during acute distention in vivo. Moreover, desensitization of VIP receptors did not occur after 30 min preincubation with either forskolin or 8-Bromo-cyclic AMP. These results indicate that mechanical distension of the ileum induces a homologous desensitization of VIP receptors on circular smooth muscle cells, which requires the occupation of its receptors by VIP.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1997

Mediators and pharmacology of visceral sensitivity: from basic to clinical investigations.

Over the last decade, the role of visceral sensitivity has been largely recognized in the pathophysiology of functional digestive disorders, particularly in the irritable bowel syndrome. These studies have highlighted the role of afferent pathways arising from the gut as a possible target for new treatments intended to relieve pain or modify altered reflexes present in such patients. These pharmacological targets have been identified mainly by studies on animal models of visceral hyperalgesia of various origins including local inflammation. Locally, several mediators are of paramount importance for sensitization of nerve endings: 5-hydroxytryptamine, bradykinin, tachykinins, calcitonin gene-related peptide, and neurotrophins. Selective antagonists to various subtypes of their receptors are currently available and have been shown to be active in these animal models. Other substances, such as somatostatin, opiold peptides, cholecystokinin, oxytocin, and adenosine, modulate the transmission of nociceptive inputs from the gut to the brain and are of clinical interest. This article reviews the current understanding of these mediators. Although these agents seem to be promising tools for the treatment of visceral hyperalgesia and its consequences (abdominal pain and disturbed reflexes), their clinical efficacy remains to be shown. A better understanding of the nature and the location of the defect in the sensory pathways may permit the selection of subgroups of patients for treatment according to the pharmacological properties of these new therapeutic agents.

Animals↗
PubMed1997

Follow-up of patients with hyperplastic polyps of the large bowel.

BACKGROUND: Adenomatous colonic polyps are accepted as premalignant lesions. There is controversy regarding the significance of the hyperplastic polyp. The aim of this study was to determine the incidence of further polyps in patients with only hyperplastic polyps on a first colonoscopy in comparison with patients without polyps and with adenomatous polyps. METHODS: Ninety patients had only hyperplastic polyps (group I). These patients were paired according to age and sex with subjects having no polyps (group II) and with patients having adenomas (group III). RESULTS: Fifty-six patients in group I had at least one follow-up examination. New polyps were found in 46.4% in group I versus 15.5% in group II (p < 0.001) and 50% in group III (NS). In group I, 30.7% of new polyps were hyperplastic and 69.3% were adenomas. In fact, 32.2% of group I patients developed further adenomas (mean 1.5 +/- 0.8 adenomas). These adenomas occurred 1 to 4 years after the first polypectomy (mean 2.4 +/- 0.8 years). Most of these adenomas were small and tubular, but 16.6% were villous or had severe dysplasia. CONCLUSION: Patients with hyperplastic polyps were 2.4 times more likely to have further adenomas than were those without polyps.

Adenoma, Villous↗
PubMed1997

The calcitonin gene-related peptide activates both cAMP and NO pathways to induce relaxation of circular smooth muscle cells of guinea-pig ileum.

The direct effects and the intracellular pathways of rCGRP were investigated on smooth muscle cells (SMC) isolated by enzymatic digestion from the circular and longitudinal layers of guinea-pig ileum. In circular SMC, rCGRP inhibited CCK8-induced contraction in a concentration-dependent manner (Cmax = 100 microM and EC50 = 0.7 +/- 0.4 nM). Preincubation of SMC with 1 microM Rp-cAMPs, a cAMP antagonist, abolished the relaxing effect of rCGRP; moreover, preincubation of SMC with 100 microM L-NAME, an inhibitor of NOS, inhibited the relaxing effect of rCGRP, hCGRP(8-37), a selective antagonist of rCGRP receptors, inhibited the rCGRP-induced relaxation in a concentration dependent manner whereas the vasoactive intestinal polypeptide (VIP) antagonist had no significant effect. In longitudinal SMC, rCGRP-induced relaxation was abolished by Rp-cAMPs, whereas L-NAME had no effect. In conclusion, rCGRP triggers different intracellular pathways to induce relaxation of circular or longitudinal intestinal SMC; cAMP is involved in cells from both layers while nitric oxide (NO) is involved only in relaxation of circular SMC.

Animals↗
PubMed1997

Standardization of barostat procedures for testing smooth muscle tone and sensory thresholds in the gastrointestinal tract. The Working Team of Glaxo-Wellcome Research, UK.

An international working team of 13 investigators met on two occasions to develop guidelines for standardizing the procedures used to test gastrointestinal muscle tone and sensory thresholds using a barostat. General recommendations were: (1) Use a thin-walled plastic bag that is infinitely compliant until its capacity is reached. Maximum diameter of the bag should be much greater than the maximum diameter of the viscus. (2) The pump should be able to inflate the bag at up to 40 ml/sec. (3) Pressure should be monitored inside the bag, not in the pump or inflation line. (4) Subjects should be positioned so that the bag is close to the uppermost surface of the body. (5) For rectal tests, bowel cleansing should be limited to a tap water enema to minimize rectal irritation. Oral colonic lavage is recommended for studies of the proximal colon, and magnesium citrate enemas for the descending colon and sigmoid. (6) If sedation is required for colonic probe placement, allow at least one hour for drug washout and clearance of insufflated air. Ten to 20 min of adaptation before testing is adequate if no air or drugs were used. (7) The volumes reported must be corrected for the compressibility of gas and the compliance of the pump, which is greater for bellows pumps than for piston pumps. (8) Subjects should be tested in the fasted state. For evaluation of muscle tone: (9) The volume of the bag should be monitored for at least 15 min. For evaluation of sensory thresholds; (10) It is recommended that phasic distensions be > or = 60 sec long and that they be separated by > or = 60 sec. (11) Sensory thresholds should be reported as bag pressure rather than (or in addition to) bag volume because pressure is less vulnerable to measurement error. (12) Tests for sensory threshold should minimize psychological influences on perception by making the amount of each distension unpredictable to the subject. (13) Pain or other sensations should be reported on a graduated scale; not "yes-no." The working team recommends verbal descriptor scales, containing approximately seven steps, or visual analog scales in which subjects place a mark on a straight line marked "none" on one end and "maximum" on the other end. (14) It is recommended that subjects should be asked to rate the unpleasantness of distensions separately from their intensity.

Animals↗
PubMed1997

Sexual abuse is more frequently reported by IBS patients than by patients with organic digestive diseases or controls. Results of a multicentre inquiry. French Club of Digestive Motility.

OBJECTIVES: The aim of this multicentre inquiry was to evaluate the prevalence of sexual abuse among IBS patients consulting a gastroenterologist, in comparison to healthy controls and patients with organic digestive diseases. PATIENTS AND METHODS: Patients with irritable bowel syndrome (IBS; Rome Criteria) were included by eight university hospitals (n = 196; 41.2 +/- 20.6 years; sex ratio (M/F) = 0.23). Control groups were: (i) patients consulting for the follow-up of non-neoplastic organic digestive diseases (n = 135; 41.5 +/- 17.0 years; 1.21); (ii) patients attending ophthalmology units (n = 200; 43.8 +/- 20.7 years; 0.81); (iii) healthy subjects seen in centres of the National Health System (n = 172; 40.3 +/- 16.3 years; 0.83). Each patient filled in an anonymous questionnaire, without help. Prevalence of sexual abuse in the various groups was compared by the chi 2 test. RESULTS: Sixty-two instance of sexual abuse (55 females, 7 males) were recorded among the 196 IBS patients (31.6%); 8 cases of verbal aggression, 4 of exhibitionism, 11 of sexual harassment, 22 sexual touches, 17 rapes. The prevalence of sexual abuse was 14.0% for the patients with organic digestive diseases (P = 0.0005 vs. IBS), 12.5% among ophthalmology patients (P < 0.0001) and 7.6% in healthy controls (P < 0.0001). Sexual abuse was accompanied by physical abuse in 23 IBS patients and 19 patients from control groups (not significant). Twenty-six IBS patients reported isolated physical abuse (14.7%) versus 40 from control groups (8.8%; P = 0.041). There was a significant trend towards more severe attacks of abuse among IBS patients than in others. CONCLUSION: This study confirms the high prevalence of sexual abuse among IBS patients consulting in Gastroenterology. Some of these patients would benefit from appropriate therapy. (In the majority of cases, this will be psychotherapy.)

Adolescent↗
PubMed1996

Intracolonic injection of glycerol: a model for abdominal pain in irritable bowel syndrome?

BACKGROUND & AIMS: Abdominal pain is the main symptom in patients with irritable bowel syndrome (IBS). Glycerol is an irritant of colonic mucosa. The aim of this study was to evaluate the effects of an intraluminal injection of glycerol on colonic motility and tone in patients with IBS and their modulation by drugs. METHODS: Colonic motility was evaluated using electromyography, and colonic tone was assessed using a barostat. Glycerol was injected in the right colon or the rectum. RESULTS: After intracolonic injection of glycerol, a strong abdominal colic occurred and was associated with an increase in long spike burst activity (+280%), which was eliminated by previous administration of lidocaine and was not observed after paraffin oil. When glycerol was injected intrarectally, abdominal pain occurred and long spike burst activity was increased (+240%) in the left colon. Simultaneously, colonic tone decreased (-70%) and high-amplitude phasic contractions occurred (10 +/- 1/patient). This rectocolonic reflex was reproducible in the same patient. Drugs acting on visceral afferent pathways (octreotide and granisetron) did not modify this reflex, whereas the spasmolytic drug phloroglucinol inhibited phasic contractions without affecting tone. CONCLUSIONS: Intraluminal injection of glycerol triggers viscerovisceral reflexes, resulting in abdominal pain in patients with IBS. It could be used as a model for the study of effects of drugs on pain in these patients.

Abdominal Pain↗
PubMed1996

VIP-induced relaxation of guinea-pig intestinal smooth muscle cells: sequential involvement of cyclic AMP and nitric oxide.

1. A possible interaction between cyclic AMP and nitric oxide (NO) in mediating the relaxant effect of vasoactive intestinal polypeptide (VIP) on intestinal smooth muscle cells has been investigated. The effects of the inhibitor of NO synthesis, NG-nitro-L-arginine methyl ester (L-NAME), have been studied on VIP-, forskolin-, and 8 bromo-cyclic AMP- induced relaxation of cells, dispersed by enzymatic digestion of muscle strips from the circular layer of guinea-pig ileum. 2. VIP alone did not modify the length of isolated muscle cells. By contrast, when the cells were contracted by cholecystokinin octapeptide, CCK8 (10 nM), VIP inhibited this contraction, inducing a concentration-dependent relaxation of the cells. Maximal relaxation was induced by 1 microM VIP (EC50 = 408.2 +/- 16.7 pM). 3. N-ethylmaleimide, inhibitors of adenylate cyclase or somatostatin, abolished the relaxing effect of VIP. (R)-p-cAMPs, an antagonist of cyclic AMP on protein kinase A also inhibited the VIP-induced relaxation by 92.1 +/- 6.3%. Inhibitors of nitric oxide synthase (NOS), L-NAME and L-NMMA, partially inhibited VIP-induced relaxation. The effect of L-NAME was reversed by L-arginine but not by D-arginine. 4. (R)-p-cAMPS and L-NAME also inhibited the cell relaxation induced either by forskolin which directly stimulates adenylate cyclase activity or 8-bromo-cyclic AMP, an analogue of cyclic AMP. 5. When cells were incubated for 30 min with dexamethasone 10 microM, a glucocorticoid known to decrease the synthesis of iNOS, the relaxing effect of a maximal concentration of VIP was decreased by 52 +/- 4% and L-NMMA had no further effect on this residual VIP-induced relaxation. Milrinone, a phosphodiesterase type III inhibitor, potentiated the relaxant effect of VIP. 6. These data demonstrate that the intracellular pathway mediating the relaxant effect of VIP in intestinal smooth muscle cells includes the sequential activation of adenylate cyclase, protein kinase A, activation of NOS and finally production of NO and cyclic GMP. NO could in turn regulate the cyclic AMP-dependent pathway of cell relaxation.

Animals↗
PubMed1996

Oxytocin increases thresholds of colonic visceral perception in patients with irritable bowel syndrome.

AIM: The effects of oxytocin on colonic perception of intraluminal distension were evaluated in 26 patients with irritable bowel syndrome (IBS), using a flaccid bag placed in the descending colon and connected to a computerised barostat. METHOD: Symptomatic responses (first sensation and pain) were evaluated during isobaric distensions (4 mm Hg increments, five minute duration, five minute interval with return to zero pressure between each step), performed automatically by the barostat, during a continuous infusion of placebo or various doses of oxytocin (10, 20, 30, and 50 mU/min). RESULTS: The distension pressure (mean (SD)) required to induce a first abdominal sensation was 17.3 (5.5) mm Hg on placebo, 19.9 (5.8) on oxytocin 10 mU/min (NS), 22.3 (6.0) mm Hg on oxytocin 20 mU/min (p < 0.01), 23.1 (6.6) mm Hg on oxytocin 30 mU/min (p < 0.01), and 24.0 (7.1) mm Hg on oxytocin 50 mU/min (p < 0.01). The distension pressure required to induce pain was 24.8 (6.3) mm Hg on placebo, 26.0 (5.8) on oxytocin 10 mU/min (NS), 33.3 (7.8) mm Hg on oxytocin 20 mU/min (p < 0.01), 34.2 (7.6) mm Hg on oxytocin 30 mU/min (p < 0.01), and 34.3 (7.9) mm Hg on oxytocin 50 mU/ min (p < 0.01). Compliance curves were not different after placebo and oxytocin injection at the different doses. Naloxone did not inhibit the effect of oxytocin. Oxytocin also did not alter somatic perception, characterised by the RIII reflex at the level of the biceps femori. CONCLUSIONS: Oxytocin significantly increases thresholds for visceral perception in IBS patients at doses equal or to greater than 20 mU/min, possibly by acting at the level of visceral afferents.

Adult↗