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Biomedical subjects

F Azpiroz

Publications and source records attributed to F Azpiroz.

At least 19 recordsLinked to original sources
PubMed2006

Selective effects of nutrients on gut sensitivity and reflexes.

BACKGROUND: Intestinal nutrients induce gut reflexes and modulate perception. AIM: To elucidate the relative potency and putative relationship of motor and sensory effects induced by different nutrients. METHODS: By paired tests carried out in sequence on healthy patients, the effect of isocaloric duodenal infusions of carbohydrates and lipids was determined on gastric compliance and on perception of gastric distension. Gastric distension at stepwise tension increments was applied using a tensostat, and perception at each tension level was measured on a 0-6 scale. In separate groups (n = 8 each), three nutrient loads were tested: (A) low (0.2 kcal/min), (B) medium (0.5 kcal/min) and (C) high (1 kcal/min). RESULTS: Values are mean (standard error). (A) Low caloric loads: both gastric perception and compliance were similar with lipids (45 (2) g, 451 (28) ml tolerated) and carbohydrates (46 (1) g, 449 (22) ml tolerated). (B) Medium caloric loads: although perception remained unchanged (46 (1) g and 46 (2) g tolerated, respectively), lipids, but not carbohydrates, partially relaxed the stomach (559 (18) v 442 (31) ml intragastric volume, respectively; p<0.05). (C) High caloric loads: lipids markedly reduced gastric tolerance and increased compliance (22 (3) g, 635 (34) ml tolerated), whereas carbohydrates did not affect perception and induced only a partial gastric relaxation (46 (1) g, 565 (46) ml tolerated; p<0.05 v lipids for both). CONCLUSION: The effects of intestinal nutrients on gastric tone are more potent than those on gastric sensation, and both depend on the caloric load and the type of nutrient.

Adult↗
PubMed2006

Intestinal tone and gas motion.

The intestine propels and evacuates large gas loads without detectable phasic contractions by manometry. We hypothesized that intestinal gas motion is produced by changes in gut tone and capacitance. In 13 healthy subjects, changes in duodenal tone were measured by a barostat during continuous perfusion of lipids (Intralipid, 1 kcal min(-1)) into the duodenum for 60 min. In separate groups, the effects of jejunal gas infusion (N2, CO2 and O2 in venous proportions at 12 mL min(-1) starting after 15 min lipid perfusion) and sham infusion were tested. Gas outflow was collected continuously via an intrarectal cannula. Duodenal lipid perfusion produced a rapid duodenal relaxation (volume increased by 48 +/- 18%; P < 0.01 vs basal). Gas infusion increased gas evacuation (184 +/- 59 mL), and this was associated with a tonic contraction of the duodenum (R = 0.86; P < 0.01) that completely reverted the lipid-induced duodenal relaxation (volume decreased by 42 +/- 13%; P < 0.05). During sham infusion only 52 +/- 28 mL of gas were evacuated (P < 0.05 vs gas infusion), and the duodenum remained relaxed due to the effect of lipids (0 +/- 1% volume reduction; ns). In conclusion, intestinal gas propulsion and clearance is associated with a tonic contraction of the gut wall and reduced gut capacitance.

Adult↗
PubMed2005

The external anal sphincter and the role of surface electromyography.

Assessment of the neuronal control of the external anal sphincter (EAS) has long been restricted to investigating patients with defecation disorders by invasive tools such as needle electromyography (EMG), while less invasive techniques have been regarded as non-suitable for diagnostic purposes. Multichannel surface EMG by means of electrode arrays applied to anal sphincter muscle records and identifies individual motor unit action potentials, their place of origin along the circumference, their repetitive firing frequency, and their progression along the muscle fibres at different levels within the anal canal. These data shed doubts on conventional knowledge about the anatomy of the EAS muscle, and confirms new concepts of anatomical differences between gender. This may eventually be transferred to a new understanding of the role of symmetry and asymmetry of pelvic floor innervation and its role in the pathogenesis of fecal incontinence.

Adult↗
PubMed2005

The puborectalis muscle.

The role of the levator ani and puborectalis muscle in preserving continence has been underestimated in the past, due predominantly to technical difficulties to investigate its proper function in healthy subjects, and its dysfunction as in patients with incontinence problems. This has recently been overcome by applying new investigational procedures such as a perineal dynamometer which measures the traction exerted by the levator ani on an intrarectal balloon catheter, or by multi-electrode arrays recording the generation of motor unit action potentials from various parts of the puborectalis muscle sling via intrarectal surface electrodes. Both techniques have the potential to provide new insights into the physiology of defecation and the pathophysiology of incontinence and constipation.

Anal Canal↗
PubMed2005

Impaired reflex control of intestinal gas transit in patients with abdominal bloating.

BACKGROUND: Patients with abdominal bloating and distension exhibit impaired transit of intestinal gas which may lead to excessive gas retention and symptoms. Furthermore, we have previously shown that intestinal gas transit is normally accelerated by rectal distension. We hypothesise that in patients with functional bloating this modulatory mechanism fails and impairs gas transit. METHODS: In 12 healthy subjects and eight patients with abdominal bloating we compared, by paired studies, the effect of rectal versus sham distension on intestinal gas transit. Gas was infused into the jejunum (12 ml/min) for three hours with simultaneous perfusion of lipids into the duodenum (Intralipid 1 kcal/min) while measuring evacuation of gas per rectum. RESULTS: In healthy subjects, duodenal lipid infusion produced gas retention (409 (68) ml) which was prevented by rectal distension (90 (90) ml; p<0.05 v sham distension). In contrast, rectal distension in patients with abdominal bloating failed to reduce lipid induced gas retention (771 (217) ml retention during rectal distension v 730 (183) ml during sham distension; NS; p<0.05 v healthy controls for both). CONCLUSION: Failure of distension related reflexes impairs intestinal gas propulsion and clearance in patients with abdominal bloating.

Abdomen↗
PubMed2005

Intestinal gas dynamics: mechanisms and clinical relevance.

Patients with functional gut disorders, irritable bowel disease, and related syndromes frequently attribute their symptoms to intestinal gas. While patients are usually convinced of their interpretation, the doctor has few arguments to confirm or refute it, and in this context intestinal gas has become a myth. Studies of intestinal gas dynamics have demonstrated subtle dysfunctions in intestinal motility. Hopefully, extension of these studies may help both in the classification of patients complaining of gas symptoms based on pathophysiological mechanisms, and in identification of objective markers to test mechanistically oriented treatment options.

Flatulence↗
PubMed2004

Technologies in the evaluation of irritable bowel syndrome.

During a meeting in The Hague, The Netherlands, the IBiS Club evaluated the most important techniques that can be used in the investigation of irritable bowel syndrome, either in the context of scientific research or as a clinical diagnostic tool. In each of these, the relevance of findings made in irritable bowel syndrome was balanced against the applicability of the technique. The discussion of the group is summarized in this paper.

Anal Canal↗
PubMed2004

Innervation zones of the external anal sphincter in healthy male and female subjects. Preliminary results.

OBJECTIVES: The objective of this work was to investigate the distribution of the innervation zones of the motor units that make up the external anal sphincter (EAS) in healthy males and females. METHODS: A cylindrical probe carrying a circumferential array of 16 electrodes was used to detect the generation, propagation and extinction of individual motor unit action potentials (MUAPs) at 1, 2, and 3 cm depth from the orifice of the anal canal during maximal voluntary contractions of the EAS. Fifteen healthy males and 37 healthy nulliparous females were investigated. RESULTS: IZs could be detected in all males and in 34 out of 37 females. In the males, the IZs are scattered in the right and left hemisphincter at each of the three levels and their distribution is not affected by depth. In the females, the distribution is also concentrated in the right and left hemisphincter at depth 1 cm but is more uniform at depth 2 cm and more concentrated in the dorsal and ventral regions at depth 3 cm. ANOVA shows a statistically significant dependence of the IZ distribution on depth only in females and not in males. CONCLUSIONS: It is concluded that (a) IZs of the EAS can indeed be detected with a circumferential array placed at different depths along the anal canal; (b) large individual variability is observed, and (c) IZs show similar distribution at the three depth levels in males and different distributions in females.

Adult↗
PubMed2004

Ileal brake failure in streptozotocin-induced diabetic rat.

BACKGROUND: Diabetes mellitus frequently alters gastrointestinal function, but the pathophysiology of the diabetic gut has not been fully elucidated. Our aim was to characterize the enterogastric modulation of gastric emptying in an experimental model of diabetic rat and to determine the putative consequences of impaired regulation on glycaemic control. METHODS: Studies were performed in streptozotozin-induced diabetic and control groups of male Sprague-Dawley rats. In rats fitted with chronic ileal cannulae, gastric emptying of a peptide meal was measured during ileal infusion of either lipids (ileal brake) or saline. The influence of the ileal brake mechanism on blood glucose levels after oral administration of a glucose solution was also evaluated. RESULTS: Diabetic rats exhibited a precipitous gastric emptying (80% +/- 3% versus 57% +/- 3% in controls; P < 0.05). Ileal lipids delayed gastric emptying in control (38 +/- 4%; P < 0.05 versus ileal saline) but not in diabetic animals (77 +/- 5%; N.S. versus ileal saline). As the ileal brake contributes to the management of postprandial blood glucose levels (114 +/- 4.9 mg/dL after ileal lipids versus 134 +/- 7.8 mg/dL after ileal saline in control rats; P < 0.05), the failure of this mechanism in diabetic rats worsens glycaemic control after feeding (455 +/- 20.4 mg/dL after ileal lipids versus 399 +/- 8.7 mg/dL after ileal saline; P < 0.05). CONCLUSION: Experimental diabetes impairs the ileal brake mechanism and disturbs gastric emptying. These abnormalities may contribute to difficult glycaemic control.

Animals↗
PubMed2004

Sites of symptomatic gas retention during intestinal lipid perfusion in healthy subjects.

BACKGROUND: Gas pooling within the gut may produce abdominal symptoms but the segment of the intestine responsible for gas retention is unknown. Our aim was to determine the role of the proximal and distal bowel in symptomatic gas accumulation using an experimental model of gas retention triggered by intraluminal lipids. SUBJECTS: Sixteen healthy subjects. METHODS: A gas mixture (N2, O2, and CO2 in venous proportions) was infused into the intestine at12 ml/min for three hours and gas evacuation was continuously measured via an anal cannula connected to a barostat. Abdominal perception and girth changes were measured at 10 minute intervals. Lipids (1 kcal/min) were simultaneously perfused either into the duodenum (n = 8) or into the ileum (n = 8). Each subject was studied twice on separate days, with gas infused into the jejunum or ileum. RESULTS: Duodenal lipids produced retention of gas infused into the jejunum (646 (62) ml) but the volume retained was much smaller when gas was infused directly into the ileum (262 (90) ml; p<0.05). The effects on gas retention were even more pronounced during ileal perfusion of lipids (1546 (184) ml during jejunal gas infusion and 847 (142) ml during ileal gas infusion; p<0.05). Abdominal distension correlated with the volume of gas retained (r = 0.87; p<0.001). Healthy subjects tolerated gas retention, and significant symptoms (score 3.7 (0.8)) developed only during jejunal gas infusion plus ileal lipid perfusion when gas retention was very large. CONCLUSION: Intraluminal lipids induce intestinal gas retention, predominantly acting on the proximal small bowel.

Abdomen↗
PubMed2003

Intestinal gas distribution determines abdominal symptoms.

BACKGROUND: Patients with functional gut disorders manifest poor tolerance to intestinal gas loads but the mechanism of this dysfunction is unknown. AIM: Our aims were firstly, to explore the relative importance of the amount of intestinal gas versus its distribution on symptom production, and secondly, to correlate gut motility and perception of gas loads. SUBJECTS: Fourteen healthy subjects with no gastrointestinal symptoms. METHODS: In each subject a gas mixture was infused (12 ml/min) either into the jejunum or rectum for one hour during blocked rectal gas outflow, and subsequently gas clearance was measured over one hour of free rectal evacuation. We measured abdominal perception, distension, and gut tone by duodenal and rectal barostats. RESULTS: Similar magnitude of gas retention (720 ml) produced significantly more abdominal symptoms with jejunal compared with rectal infusion (perception score 4.4 (0.4) v 1.5 (0.5), respectively; p<0.01) whereas abdominal distension was similar (15 (2) mm and 14 (1) mm girth increment, respectively). Jejunal gas loads were associated with proximal contraction (by 57 (5)%) and colonic loads with distal relaxation (by 99 (20)%). CONCLUSION: The volume of gas within the gut determines abdominal distension whereas symptom perception depends on intraluminal gas distribution and possibly also on the gut motor response to gas loads.

Abdomen↗
PubMed2003

Influence of body posture on intestinal transit of gas.

BACKGROUND: Patients describe that body posture may affect their abdominal bloating, distension, and flatulence, but whether changes in position have objectively demonstrable effects, either beneficial or deleterious, has not been investigated. AIM: To determine the effect of body posture, upright versus supine, on intestinal transit of gas loads. SUBJECTS: Eight healthy subjects without gastrointestinal symptoms. METHODS: In each subject a gas mixture was continuously infused into the jejunum (12 ml/min) for three hours, and gas evacuation, clearance of a non- absorbable gaseous marker, perception, and abdominal girth were measured. Paired studies were randomly performed in each subject on separate days in the upright and supine positions. RESULTS: In the upright position, intestinal gas retention was much smaller than when supine (13 (52) ml v 146 (75) ml retention at 60 minutes, respectively; p<0.05), and clearance of the gas marker was expedited (72 (10)% clearance v 49 (16)% at 60 minutes, respectively; p<0.05). The gas challenge test was well tolerated both in the upright and supine positions without abdominal distension. CONCLUSION: Body posture has a significant influence on intestinal gas propulsion: transit is faster in the upright position than when supine.

Adult↗
PubMed2003

Role of alimentation in irritable bowel syndrome.

BACKGROUND: Different food items are made responsible for irritable bowel syndrome (IBS) symptoms, but the physiopathology of IBS remains unclear. AIMS: During a meeting in Nice, France, experts of the European Working Team of the IBiS Club discussed selected data regarding the relationships between alimentation, food items (including fibers) and IBS symptoms. METHODS/RESULTS: Food allergy remains a difficult diagnosis, but medical and general history, presence of general symptoms such as skin rash, and hypersensitivity tests may help in achieving a positive diagnosis. On the other hand, food intolerance is more confusing because of the subjectivity of the relationship between ingestion of certain foods and the appearance of clinical symptoms. Different food items which are commonly implicated in adverse reactions mimicking IBS were found to be stimulants for the gut, suggesting that patients with predominant diarrhea IBS have to be carefully questioned about consumption of different kinds of food (i.e., coffee, alcohol, chewing gum, soft drinks) and not only on lactose ingestion. Gas production is discussed on the basis of retention of intestinal gas as well as on malabsorption of fermentable substrates. The role of a large amount of this kind of substrate reaching the colon is suggested as a potential mechanism of IBS-type symptoms in overeating patients. Regarding the role of fiber in IBS, the expert group concluded that fibers are not inert substances and that they could trigger pain or bloating in some IBS patients. CONCLUSION: Despite numerous reviews on this subject, it is very difficult to give general dietary advice to IBS patients, but dieteticians may have a positive role in managing such patients.

Colon↗
PubMed2002

Hypersensitivity in functional gastrointestinal disorders.

Patients with functional gastrointestinal disorders may have visceral sensory dysfunction so that physiological stimuli induce their symptoms. The clinical significance of altered perception-that is, its relation to clinical symptoms-remains unclear. Data indicate that sensory dysfunction is associated with altered reflex activity. Hence evidence of combined sensory-reflex dysfunction as a common pathophysiological mechanism in various functional gastrointestinal disorders would suggest that they are different forms of the same process. Altered reflex activity and altered conscious perception of gastrointestinal stimuli may combine to differing degrees, and their interaction may produce clinical symptoms.

Colonic Diseases, Functional↗
PubMed2002

The rectum: a window to irritable bowel syndrome?

This report summarizes current concepts and information gathered to date about the rectum in the irritable bowel syndrome (IBS) that were presented at the 10th meeting of IBiS Club held in Leuven, Belgium. A working group of experts in the field of IBS discussed whether the rectum or the whole colon is the better site to test in IBS patients and provided suggestions for a number of areas where further advances are required.

Biopsy↗