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Biomedical subjects

F Mearin

Publications and source records attributed to F Mearin.

At least 55 records · Page 3Linked to original sources
PubMed1995

Gastric tone determines the sensitivity of the stomach to distention.

BACKGROUND/AIMS: Whether meal-related symptoms such as postcibal epigastric fullness and discomfort are caused by hypotonic gastric expansion or gastric hypertension is unknown. This study investigated whether symptoms in healthy individuals in response to gastric distention are produced by gastric expansion or by an increase in intragastric pressure. METHODS: Increasing gastric distentions (for 5 minutes at 5-minute intervals) at fixed pressure levels (in 2-mm Hg increments) and at fixed volume levels (in 200-mL increments) were performed in 10 healthy subjects per group; perception was measured on a 0-6 scale. Distentions were performed during intravenous infusion of saline (basal) and during gastric relaxation by intravenous administration of glucagon (4.8-micrograms/kg bolus plus 9.6 micrograms.kg-1.h-1 infusion). RESULTS: The same distending pressure tested produced 30% +/- 9% larger intragastric volumes and 80% +/- 44% higher perception scores when the stomach was relaxed by glucagon (P < 0.05 vs. basal for both). In contrast, the same distending volumes tested produced 25% +/- 7% lower intragastric pressures and 21% +/- 12% lower perception scores when the stomach was relaxed (P < 0.05 vs. basal for both). CONCLUSIONS: Epigastric symptoms in response to gastric distention are influenced by both the intragastric pressure and the intragastric volume.

Adult↗
PubMed1995

Impaired gastric relaxation in patients with achalasia.

Achalasia is considered a primary motility disorder confined to the oesophagus. The lower oesophageal sphincter (LOS) in achalasia is frequently hypertonic and manifests absent or incomplete relaxation in response to deglution. On the other hand, the LOS and the proximal stomach act physiologically as a functional unit whereby relaxation of the LOS during deglution is associated with receptive relaxation of the proximal stomach. Thus, this study investigated the hypothesis that impaired LOS relaxation in patients with achalasia might be associated with impaired relaxation of the proximal stomach. The study consisted of 20 patients with achalasia and 10 healthy controls. Gastric tone variations were quantified using an electronic barostat. Firstly, the study established the basal gastric tone (intragastric volume at the minimal distending pressure+1 mm Hg) and gastric compliance (volume/pressure relation) during isobaric distension (increasing stepwise the intragastric pressure from 0 to 20 mm Hg up to 600 ml). Secondly, the gastric tone response to cold stress (hand immersion into ice water for five minutes) or to control stimuli (water at 37 degrees) was determined. Basal gastric tone mean (SEM) was similar in achalasia and in healthy controls (125 (9) ml v 138 (9) ml, respectively). Compliance was linear and similar in both groups, which also showed similar gastric extension ratios (58 (7) ml/mm Hg v 57 (6) ml/mm Hg). Cold stress induced a gastric relaxatory response that, as a group, was significantly lower in achalasia than in healthy controls (volume: 43 (20) ml v 141 (42) ml; p < 0.05). The responses in each group were not uniform, five of the 20 patients with achalasia showed definite (volume > 100 ml) relaxatory responses whereas four of the 10 healthy controls did not. In conclusion, reflex gastric relaxation is impaired in most patients with achalasia showing that the proximal stomach, and not exclusively the oesophagus, may be effected by the disease.

Adolescent↗
PubMed1995

Does Helicobacter pylori infection increase gastric sensitivity in functional dyspepsia?

The role of Helicobacter pylori infection in the pathogenesis of functional dyspepsia is debated. It is known that a substantial fraction of dyspeptic patients manifest a low discomfort threshold to gastric distension. This study investigated the symptomatic pattern in 27 H pylori positive and 23 H pylori negative patients with chronic functional dyspepsia, and potential relations between infection and gastric hyperalgesia. Specific symptoms (pain, nausea, vomiting, bloating/fullness, early satiety) were scored from 0 to 3 for severity and frequency (global symptom scores: 0-15). The mechanical and perceptive responses to gastric accommodation were evaluated with an electronic barostat that produced graded isobaric distensions from 0 to 20 mm Hg in 2 mm Hg steps up to 600 ml. Gastric compliance (volume/pressure relation) and perception (rating scale: 0-10) were quantified. Standard gastrointestinal manometry and recorded phasic pressure activity at eight separate sites during fasting and postprandially were also assessed. H pylori positive and H pylori negative patients manifested similar severity and frequency of specific symptoms and global symptom scores (mean (SEM)) (severity: 9.5 (2.0) v 9.0 (2.1); frequency: 10.8 (2.0) v 9.7 (2.2)). No differences were seen either in gastric compliance (53 (4) ml/mm Hg v 43 (3) ml/mm Hg) or in gastric perception of distension (slope: 0.50 (0.05) v 0.53 (0.06)). Postprandial antral motility was significantly decreased in H pylori positive patients (two hours motility index: 10.4 (0.6) v 12.6 (0.5); p < 0.05). It is concluded that H pylori infected patients with functional dyspepsia present no distinctive symptoms by comparison with H pylori negative counterparts and H pylori infection is associated with diminished postprandial antral motility but it does not increase perception of gastric distension.

Adolescent↗
PubMed1995

Gastroparesis and dyspepsia in patients with diabetes mellitus.

About one-half of patients with insulin- or non-insulin-dependent diabetes have delayed gastric emptying (diabetic gastroparesis). Some of them complain of epigastric pain, nausea, vomiting or postprandial fullness (diabetic dyspepsia), although only a minority are severely symptomatic. Diabetic gastroparesis is clinically relevant not only by virtue of the symptoms induced but also because it may contribute to inadequate glycaemic control and impaired absorption of orally administered drugs. Recent data suggest that abnormal blood glucose control, not only autonomic neuropathy, contribute to the pathogenesis of disordered gastric motility. In most cases diabetic gastroparesis is diagnosed clinically in the absence of demonstrable lesions of the upper gastrointestinal tract. To evaluate gastric emptying, scintigraphy is the 'gold standard'. Gastrokinetic drugs are of help in the treatment of gastroparesis: erythromycin is the first choice in acute presentations and cisapride for chronic symptoms. New macrolides with prokinetic action and devoid of antibacterial properties are very promising and should add another pharmacologic approach to control dyspepsia and gastroparesis in diabetic patients in the future.

Diabetes Complications↗
PubMed1994

Effect of experimental cold pain stress on gastroesophageal junction.

The impact of stress on gastroesophageal reflux and antireflux mechanisms remains largely unexplored. To a major extent, reflux depends on a balance between gastroesophageal junction resistance to flow and gastric tone. We hypothesized that these two forces could be differently affected by stress, and to test the hypothesis we quantified in 10 healthy volunteers the effect of an acute stressful stimulus (cold pain) upon both gastroesophageal junction resistance (measured by a pneumatic resistometer) and gastric tone (measured by an electronic barostat). Such measurements were performed both under basal conditions and during stress stimulation (hand immersion in cold water for 5 min), on two separate days. The cardiovascular autonomic response was simultaneously monitored as changes in blood pressure and pulse rate. We found that, taken as a whole, cold stress significantly decreased gastroesophageal resistance (flow increase from 347 +/- 29 ml/min to 526 +/- 58 ml/min) as well as gastric tone (volume increase from 147 +/- 10 ml to 218 +/- 17 ml) (P < 0.02 for both). However, responses showed marked intra- and interindividual variation. Moreover, we found no relationship between changes in resistance to flow at the junction and either the cardiovascular autonomic response or the discomfort produced by cold stress. Changes in gastric tone were similarly unrelated to autonomic and perceptive responses. We conclude that in man experimental stress induced by cold pain tends to disrupt each of two opposite mechanisms that control gastroesophageal reflux: gastroesophageal resistance to flow and gastric tone. However, since both are decreased by stress, gastroesophageal function is largely maintained.

Adult↗
PubMed1994

Forceful dilatation under endoscopic control in the treatment of achalasia: a randomised trial of pneumatic versus metallic dilator.

Forceful dilatation under endoscopic control is a well established treatment of achalasia; several different types of dilators can be used. This study prospectively compared the clinical and manometric efficacy of a single dilatation using two different dilators. Forty one patients were randomly assigned to forceful dilatation under endoscopic control with either a pneumatic dilator (n = 17) or a metallic dilator (n = 24). Thereafter, the patients received periodic clinical and manometric evaluation for one year (before and one, six, and 12 months after dilatation). One month after dilatation all but one of the subjects in each group had experienced good to excellent results and their clinical improvement persisted for the one year follow up. Two patients (one in each group) were perforated during the procedure and required surgical treatment. Recovery was uneventful in both cases. Resting lower oesophageal sphincter pressure (mean (SEM)) significantly and similarly decreased after both methods of dilatation (pneumatic dilator: before dilatation 37 (3) mm Hg, one year after dilatation 18 (3) mm Hg; metallic dilator: before dilatation 34 (2) mm Hg, one year after dilatation 17 (3) mm Hg; p < 0.05 for both). It is concluded that in the treatment of achalasia a single dilatation under endoscopic control with either pneumatic or metallic dilator yield comparable clinical and manometric results and similar complication rates. The use of one or other dilator should depend more on the preference and experience of the endoscopist than on the type of device.

Catheterization↗
PubMed1994

[Nitric oxide and Hirschsprung's disease: a causal relation biochemically, immunohistochemically and functionally demonstrated].

UNLABELLED: Hirschsprung's disease may be due to impaired nonadrenergic-noncholinergic inhibitory input in the aganglionic segment of the colon. It has been suggested that nitric oxide (NO) might be the lacking neurotransmitter. Thus, our specific aims were to determine in ganglionic and aganglionic segments: 1. The activity of the NO synthetase (NO-S); 2. The location of this enzyme; and 3. The "in vitro" basal motor activity of the muscle strips and their responses to an NO donor and to an NO antagonist. METHODS: NO synthetase activity was quantified in samples of tissue from both aganglionic and ganglionic segments obtained during surgery in 6 patients with Hirschsprung's disease by the transformation of 14C-L-arginine into 14C-L-citrulline in tissue homogenates. Immunohistochemical staining of the tissues was performed using a polyclonal antibody raised against a peptide sequence of rat brain NO synthetase. Furthermore, in 2 patients we measured "in vitro" the tonic response of muscle strips to an exogenous NO donor (sodium nitroprusside) and to an NO antagonist (L-NAME). RESULTS: NOS activity was undetectable in every aganglionic segment whereas it was present in all ganglionic segments (0.49 +/- 0.09 pmol citrulina/mg.min; mean +/- SE). Immunohistochemically, NO-S was absent in the myenteric plexus of aganglionic segments and it was present in ganglionic segments. "In vitro" basal motor activity of ganglionic segments was normal, with presence of low-frequency contractions (LFC) and summation contraction (SC); in aganglionic segments SC were absent. Sodium nitroprusside induced a marked relaxation (90% from basal) in muscle strips, both aganglionic and ganglionic, precontracted with bethanocol.(ABSTRACT TRUNCATED AT 250 WORDS)

Arginine↗
PubMed1993

Patients with achalasia lack nitric oxide synthase in the gastro-oesophageal junction.

The abnormal function of the lower oesophageal sphincter in achalasia is likely to be due to impaired nonadrenergic, noncholinergic (NANC) inhibitory input. Since recent studies in animals suggest that nitric oxide (NO) is implicated physiologically in the inhibitory responses of the lower oesophageal sphincter, we have investigated whether the synthesis of NO is altered in the gastro-oesophageal junction of patients with achalasia. NO synthase activity was investigated in samples of tissue from the gastro-oesophageal junction obtained during surgery in eight patients with typical achalasia and six non-achalasic controls who underwent oesophagectomy for reasons other than sphincter dysfunction. The NO synthase activity was determined by the transformation of 14C-L-arginine into 14C-L-citrulline in tissue homogenates. In addition, immunohistochemical staining of the tissues was performed using a polyclonal antibody raised against a peptide sequence of rat brain NO synthase. Furthermore, the relaxant response to an exogenous NO donor (sodium nitroprusside, SNP) was measured in vitro in muscle strips obtained from two patients with achalasia and in two non-achalasic controls. NO synthase activity was detected in each of the samples obtained from six control patients (0.59 +/- 0.21 pmol mg-1 min-1; mean +/- SE). By contrast, none of the samples obtained from the eight patients with achalasia had any detectable NO synthase activity. Immunohistochemical studies confirmed the presence of NO synthase in the myenteric plexus of the gastro-oesophageal junction of control patients and its absence in achalasia. SNP relaxed muscle strips precontracted with bethanechol in both control samples and those from patients with achalasia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Gastrointestinal manometry: a practical tool or a research technique?

Gastrointestinal motility disorders constitute a major segment of digestive illness. Therefore, measurement of gut motor activity should be a desired goal. However the practical usefulness of gastrointestinal manometry is controversial. In this report we review the theoretical, technical, and practical problems posed by gastrointestinal manometry in health and in disease. Special emphasis is put on aspects pertaining to the indications and clinical applicability of the technique. New methodological developments that allow measurement of motor functions of the proximal stomach and the antroduodenal junction are also examined. Gastrointestinal manometry is potentially helpful in the diagnostic evaluation of patients presenting with upper gastrointestinal symptoms without demonstrable anatomic alteration as evidence by conventional diagnostic evaluation. It may help to localize the affected region of the gut as well as to monitor the evolution of the motor disorder and to determine the effect of pharmacological treatment. For a complete evaluation of upper gastrointestinal motility it is important to record gastric activity at the same time as in the intestine, during fasting and also postprandially. Manometry may help to determine the type of abnormal motor pattern that occurs in a given motor disorder. However, at the present time no specific abnormalities for specific diseases have been described. Thus, alterations in upper gut motility due to lesions at different levels of the brain-gut axis (central nervous system, autonomic nervous system or myenteric plexus) may produce a similarly deranged manometric pattern. Moreover, relations between a particular motor abnormality and the symptoms that the patient complains of may be quite variable. Still, we conclude that measurement of gastrointestinal motility has matured and proven its value to an extent that its application to clinical gastroenterology in carefully selected instances is appropriate and timely.

Gastric Emptying↗
PubMed1991

Effect of obesity on gastroesophageal resistance to flow in man.

Chronic (obesity) and acute intraabdominal pressure increases appear to favor gastroesophageal reflux, but the mechanism is not completely understood. We hypothesized that it could be due to an alteration in the resistance gradient between the stomach and the gastroesophageal junction, even increasing intragastric resistance above resistance at the gastroesophageal junction. Hence, we used a pneumatic resistometer to measure gastric and gastroesophageal resistance to flow in 11 lean healthy controls and eight morbidly obese individuals without gastroesophageal reflux disease. Resistance was quantified at rest and during acute intraabdominal pressure increases, both in the recumbent and sitting positions. We found that gastroesophageal junction resistance was higher than gastric resistance in lean as well as in obese subjects (P less than 0.001). In obese individuals both gastric and gastroesophageal junction resistance were increased (P less than 0.001), thus a normal gastric-gastroesophageal junction resistance gradient was maintained. Body position did not modify resistance. Acute increases in intraabdominal pressure decreased the gastric-gastroesophageal junction resistance gradient similarly in obese and lean subjects. We conclude that obesity by itself does not appear to predispose to gastroesophageal reflux, but it creates intraabdominal conditions that may favor reflux whenever the gastroesophageal barrier becomes weakened.

Adult↗
PubMed1991

The origin of symptoms on the brain-gut axis in functional dyspepsia.

It was hypothesized that symptoms in functional dyspepsia are originated by an altered mechanism at the brain-gut axis (one or several) in the process of gastric accommodation to a meal. To test the key mechanisms potentially involved in symptomatic gastric accommodation, the sensorial responses (on a 0-10 perception score) and the gastric tone responses (by electronic barostat) to either gastric accommodation (n = 10) or to cold stress (n = 10) were measured in 20 patients with functional dyspepsia and 20 healthy controls. The mechanical accommodation of the stomach to gastric distention (compliance) was similar in patients (52 +/- 8 mL/mm Hg) and controls (57 +/- 6 mL/mm Hg). However, isobaric gastric distention elicited more upper abdominal discomfort in dyspeptics than in controls (perception scores, 4.7 +/- 0.9 vs. 1.1 +/- 0.5, respectively; mean +/- SE; P less than 0.005). Cold stress induced a similar gastric relaxatory response in dyspeptics and controls (delta vol, 145 mL +/- 40 mL vs. 141 mL +/- 42 mL, respectively); hand perception (scores, 8.3 +/- 0.4 vs. 7.9 +/- 0.4, respectively) and autonomic responses were also similar. It is concluded that an abnormal afferent sensorial pathway (altered gastric perception) may be a major mechanism of symptom production in functional dyspepsia.

Adult↗
PubMed1990

Effect of transcutaneous nerve stimulation on esophageal motility in patients with achalasia and scleroderma.

It has been suggested that low-frequency transcutaneous electric nerve stimulation (TENS) alleviates the dysphagia produced by achalasia and scleroderma of the esophagus. The present study was conducted to elucidate whether TENS treatment improves dysphagia because of changes it induces on esophageal motility. We studied nine achalasia patients before forceful dilatation of the cardias, nine achalasia patients after dilatation, and nine patients with scleroderma. High-frequency TENS was applied to the hand for 30 min while esophageal motility was monitored by manometry. In none of the groups did TENS produce any change in the basal tone of the lower esophageal sphincter, lower esophageal sphincter relaxation, or esophageal body wave amplitude. Low-frequency TENS, used in another seven untreated achalasia patients, also did not improve esophageal motility. Our data indicate that high- or low-frequency TENS does not induce detectable changes in esophageal motility in patients with achalasia or scleroderma.

Adolescent↗