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Biomedical subjects

L M Akkermans

Publications and source records attributed to L M Akkermans.

At least 91 records · Page 5Linked to original sources
PubMed1995

Dynamic characteristic of gastro-oesophageal reflux in ambulatory patients with gastro-oesophageal reflux disease and normal control subjects.

BACKGROUND: The aim of the study was to investigate the dynamic characteristics of pathologic gastro-oesophageal reflux. METHODS: Five-channel ambulatory 24-h oesophageal pH monitoring was performed in 19 gastro-oesophageal reflux disease patients (age, 21-74 years) and in 19 healthy volunteers (age, 21-64 years). The pH was recorded at 3, 6, 9, 12, and 15 cm from the lower oesophageal sphincter (LOS), using a sample frequency of 4 Hz for each channel. Automated analysis included calculation of the ascending velocity of the refluxate and duration and extent (cm above the LOS) of all individual reflux episodes. RESULTS: In the patients more upright reflux episodes reached the proximal sensor than in the controls (20% and 11%, respectively, P < 0.01). The duration of the reflux episodes (measured at 3 cm above the LOS) was longer in the patients than in controls (P < 0.0001). This effect was independent of the proximal extent of the reflux episodes. Ascending velocities of upright acid reflux were higher in controls (1.8 to 2.7 cm/sec) than in patients (0.7 to 2.2 cm/sec; P = 0.01). CONCLUSIONS: The dynamic characteristics of pathologic reflux differ significantly from those of physiologic reflux.

Adult↗
PubMed1995

Cisapride and structural analogs selectively enhance 5-hydroxytryptamine (5-HT)-induced purinergic neurotransmission in the guinea pig proximal colon.

In the guinea pig proximal colon, 5-hydroxytryptamine (5-HT) stimulates neuronal 5-HT1-like receptors to induce relaxations that are mediated by nitric oxide and ATP. In the current study, the effects of cisapride and structural analogs on these 5-HT-induced relaxations were investigated. In the continuous presence of ketanserin (0.3 microM) and tropisetron (3 microM) to block contractions via 5-HT2A, 5-HT3 and 5-HT4 receptors, 5-HT induced relaxations that yielded a biphasic concentration-response curve. Cisapride (0.1-1 microM) enhanced the second phase of the concentration-response curve to 5-HT by about 20% to 40%, whereas from 0.3 microM onwards, it inhibited the first phase. Also in the presence of cisapride (0.3 microM), tetrodotoxin (0.3 microM) abolished the relaxations to 5-HT. Cisapride (0.3 microM) did not affect the concentration-response curves to isoprenaline, nitroglycerin, nitroprusside or exogenous ATP, which demonstrated its specificity. The 5-HT relaxation-enhancing effects of cisapride were not mimicked by phentolamine (1 microM), NAN-190 (0.03 microM), spiperone (1 microM), citalopram (0.3 microM), paroxetine (0.3 microM), pargyline (100 microM) or SDZ 205-557 (0.3 microM). In the presence of the inhibitor of nitric oxide synthesis, NG-nitro-L-arginine (100 microM), cisapride (0.3 microM) still enhanced the remaining relaxations to 5-HT (2-3-fold). However, in the presence of the P2-purinoceptor antagonist suramin (300 microM), cisapride did not enhance the relaxations to 5-HT. In the presence of NG-nitro-L-arginine, the cisapride-enhanced relaxations to 5-HT were inhibited by about 90% by suramin. We conclude that in the guinea pig colon, cisapride selectively facilitates the suramin-sensitive, ATP-mediated part of the relaxation to 5-HT via an unidentified effect on intramural nerves.

Adenosine Triphosphate↗
PubMed1995

Antroduodenal manometry: 24-hour ambulatory monitoring versus short-term stationary manometry in patients with functional dyspepsia.

OBJECTIVES: To examine the interdigestive and postprandial antroduodenal motility patterns of patients with functional dyspepsia using prolonged ambulatory antroduodenal manometry and to compare these findings with conventional stationary manometry. METHODS: Prolonged ambulatory and short-term stationary antroduodenal manometry were performed in 10 patients with functional dyspepsia and in 10 healthy volunteers (controls). RESULTS: During stationary manometry only a few interdigestive motor complex (MMC) cycles were recorded. Using the ambulatory technique, fewer MMC cycles were observed in patients than in controls (2.2 +/- 0.63 and 4.1 +/- 0.54, respectively; P = 0.030). During phase II of the MMC, both techniques showed a higher antral motility index in patients (P = 0.017 and P = 0.049 for stationary and ambulatory manometry, respectively). The postprandial antral motility index was similar for patients and controls using stationary manometry. With the ambulatory technique, the antral motility index 1-1.5 h after breakfast was lower in patients than in controls (P = 0.020). Both techniques showed that the patients had a higher duodenal motility index after dinner and after breakfast (P < 0.05). Both techniques revealed more burst activity in patients than in controls (stationary: 10.7 versus 1.8% of the time; ambulatory: 1.7 versus 0.2% of the time; P = 0.004 and P = 0.051, respectively). Using a 10-min window period before the onset of symptoms, seven symptom episodes (33.3%) were found to be related to burst activity and retrograde or non-propagated phase III activity. CONCLUSIONS: Ambulatory manometry is superior to stationary manometry for evaluating patients with functional dyspepsia, because patients can be studied for a prolonged period (allowing adequate evaluation of interdigestive abnormalities) and under physiological conditions. Prolonged monitoring also allows assessment of the relationship between symptoms and motor abnormalities.

Adult↗
PubMed1994

Gastric myoelectrical activity in patients with type I diabetes mellitus and autonomic neuropathy.

In patients with diabetes mellitus and gastroparesis, dysrhythmias of gastric myoelectrical activity, especially tachygastrias, are thought to be involved in the pathogenesis of dyspeptic symptoms. Using surface electrogastrography we studied the prevalence of these abnormalities, and their relationships to dyspeptic symptoms and the extent of cardiac autonomic neuropathy in 30 euglycemic patients with type I diabetes mellitus and 12 controls. Neither in the fasting nor in the postprandial state were differences in mean frequency of gastric electrical control activity and its variability found between patients and controls. In the fasting state, the power content of the 3 cpm component in the power spectrum of the electrogastrogram was even higher in patients than in controls (P = 0.049). In the fasting state, second harmonics of the 3 cpm fundamental gastric signal were seen more often in patients than in controls (P = 0.03). In patients with symptoms during the study, no second harmonics were found after the meal. The postprandial/fasting power ratio was decreased in patients with symptoms during the study as compared to patients without symptoms and controls (P < 0.05). The incidence of dysrhythmias, such as tachygastrias and bradygastrias, was not higher in patients than in controls (17% and 8%, respectively). No correlation was found between electrogastrographic parameters and the severity of autonomic neuropathy or dyspeptic symptoms scored before the study. In conclusion, this study has shown that patients with type I diabetes mellitus and autonomic neuropathy studied under euglycemic conditions do not have grossly disturbed myoelectrical activity, except when symptomatic during the study.

Autonomic Nervous System Diseases↗
PubMed1994

Gastric motility and emptying studies with radionuclides in research and clinical settings.

Scintigraphy remains the most reliable method to measure gastric emptying. Standardized dual-isotope radionuclide gastric emptying techniques and appropriate meals, which stimulate small bowel receptors and utilize correction factors for technical errors, are widely available for research purposes. It is now necessary to apply the same standardized techniques in clinical settings to make the test diagnostically worthwhile. It is possible to quantify gastric motor function scintigraphically and to apply this methodology to study the pathophysiology of gastric emptying in various motor disorders. Ambulatory gastric emptying methods with intraluminal gamma counting probes are currently under development.

Food↗
PubMed1994

Role of electrogastrography and gastric impedance measurements in evaluation of gastric emptying and motility.

Electrogastrography records electrical potential variations brought about by myoelectrical activity of the stomach. Abnormal myoelectrical rhythms such as tachygastrias may also be detected. Electrogastrography provides little information on gastric motility and emptying. Impedance epigastrography is a technique that uses changes in epigastric impedance to evaluate gastric emptying of large-volume liquid meals. The results are inferior to those of tomographic impedance imaging. Phasic antral contractions may lead to phasic impedance changes recorded with nonimaging techniques and a phasic signal recorded with high-speed electrical impedance tomography. However, the relationship between phasic contractions and phasic variations in impedance do not appear consistent enough to allow clinical application of the technique.

Electric Impedance↗
PubMed1994

Hyperglycemia induces abnormalities of gastric myoelectrical activity in patients with type I diabetes mellitus.

BACKGROUND/AIMS: Blood glucose concentration has been shown to be an important factor in gastric motility. However, the effect of hyperglycemia on gastric myoelectrical activity has not yet been studied in patients with diabetes. METHODS: Surface electrogastrography was performed in eight patients with type I diabetes mellitus under normoglycemic and hyperglycemic conditions (glucose clamp technique) and in eight normoglycemic control subjects. RESULTS: In the early postprandial state, the frequency of the normal pacemaker rhythm tended to be higher during hyperglycemia than during normoglycemia (3.10 +/- 0.27 vs. 2.92 +/- 0.19 cycle/min; P = 0.061). The frequency decrease that occurs immediately after a meal was found less frequently during hyperglycemia (in 25% vs. 75% of the patients; P = 0.046). Higher harmonics of the 3-cycle/min component, indicating an electrogastrographic waveform change, were found less often during hyperglycemia (in 13% vs. 63% of the patients; P = 0.039). Dysrhythmias (in particular, tachygastrias) were more prevalent during hyperglycemia (40.6% vs. 6.5% of the time; P = 0.028). No differences were found between normoglycemic patients and control subjects. CONCLUSIONS: This study has shown that hyperglycemia is an important factor in the generation of gastric myoelectrical disturbances and tachygastrias in particular.

Adult↗
PubMed1994

The symptom-association probability: an improved method for symptom analysis of 24-hour esophageal pH data.

BACKGROUND/AIMS: All methods currently used to quantify the temporal relationships between symptoms and episodes of gastroesophageal reflux, as assessed by 24-hour pH monitoring, have major shortcomings. The aim of this study was to develop and validate a simple, all-comprising statistical method to calculate the probability that gastroesophageal reflux episodes and symptoms are associated. METHODS: The 24-hour pH signal was divided into consecutive 2-minute periods. These periods and the 2-minute periods preceding the onset of symptoms were evaluated for the occurrence of reflux. Fisher's Exact Test was then applied to calculate the probability (P value) that reflux and symptom episodes were unrelated. Finally, the symptom-association probability (SAP) was calculated as (1.0 - P) x 100%. The SAP values found in 184 24-hour esophageal pH tests were compared with the symptom index and the symptom sensitivity index. RESULTS: Discordance between the SAP and the symptom index was found in 21 patients (11%) and discordance between the SAP and the symptom-sensitivity index in 28 (15%). False-positive and false-negative symptom index values occurred preferentially in patients with small and large numbers of symptom episodes during the test, respectively (P < 0.05). CONCLUSIONS: The SAP is a single, simple, quantitative measure of the strength of the association between symptoms and reflux episodes that is devoid of the disadvantages inherent to previously used methods.

Adolescent↗
PubMed1994

Influence of age on cerebral potentials evoked by oesophageal balloon distension in humans.

The recording of viscerosensory cerebral evoked potentials is a new field in the research on gastrointestinal perception. The aim of our study was to assess the relationships between age and peak amplitudes and latencies of cerebral potentials evoked by balloon distension of the human oesophagus. In 16 healthy volunteers (aged 21-59 years), cerebral evoked potentials were recorded from a midline scalp electrode, using a series of 50 rapid balloon inflations with 13 ml of air. Peak to peak amplitudes (N1-P1, P1-N2) and peak latencies (N1, P1, N2) were assessed. Inverse correlations were found between age and N1-P1 amplitude (P < 0.05), and between age and P1-N2 amplitudes (P < 0.05). N1 and P1 latencies were significantly longer in elderly patients (N1: P < 0.05; P1: P < 0.05). Amplitudes and peak latencies of cerebral potentials evoked by balloon distension of the oesophagus are age-dependent. In cerebral evoked potential studies, patients and healthy controls should be age-matched.

Adult↗
PubMed1994

Treatment of faecal incontinence in a child with sacral agenesis: the use of biofeedback training.

The case of a 14-year-old girl is presented who was born with sacral agenesis and severe, chronic constipation not responding to laxative treatment. Biofeedback was employed in the treatment of the constipation and soiling. After six treatment sessions over four months, the constipation and soiling ceased and there was no relapse during follow-up of 12 months. Although this child had an absence of S3-S5 and the coccyx, with possible innervation abnormalities, this case illustrates that biofeedback training might be a useful adjunct to existing therapies.

Adolescent↗
PubMed1994

Spatiotemporal characteristics of physiological gastroesophageal reflux.

Recent technological developments have made it possible to measure intraluminal pH simultaneously at multiple sites using one single small-caliber catheter. The aim of this study was to investigate the dynamics of physiological gastroesophageal reflux in eight ambulatory healthy volunteers (age 21-51 yr). Esophageal pH was recorded for 24 h at 3, 6, 9, 12 and 15 cm from the lower esophageal sphincter (LES), using an 8-Fr catheter containing five ion-sensitive field effect transistor (ISFET) pH transducers and a digital data logger. Signals were sampled at a rate of 4 Hz. Automated analysis included determination of the extent of the reflux (cm above LES) and calculation of the velocity of the advance of the pH front from the LES (ascending velocity), minimum pH reached, and duration of all individual reflux episodes at different segments in the esophagus. The reflux time and the number of reflux episodes/24 h showed a gradual decrease from the distal to the proximal sensor (mean +/- SE: 4.4 +/- 0.8 to 0.9 +/- 0.2% and 46 +/- 7.6 to 11 +/- 1.9, respectively). Of all reflux episodes 23% did not reach the sensor at 6 cm above the LES, and only 25% reached the most proximal sensor. Characteristically, acid refluxed rapidly (velocity 0.4-2.4 cm/s) and was cleared in a stepwise fashion. Reflux episodes of long duration at the distal sensor reached high levels in the esophagus (P < 0.001). It was concluded that ambulatory multichannel esophageal pH monitoring using ISFET technology is a valuable tool for studies on the spatio-temporal characteristics of gastroesophageal reflux.

Adult↗
PubMed1994

Manometry, profilometry, and endosonography: normal physiology and anatomy of the anal canal in healthy children.

Normal and manometric and profilometric values and normal endosonographic features of the anal canal are required for evaluation of pathological conditions such as slow-transit constipation, anorectal outlet obstruction, and Hirschsprung's disease, status after surgery for imperforate anus, and other anal abnormalities. Anorectal manometry, profilometry (rapid-pull-through, three-dimensional, eight-channel radial manometry), and endosonography were carried out in 13 healthy children. A significant correlation was demonstrated between conventional manometric and profilometric maximal squeeze pressure of the external anal sphincter (EAS). However, the maximal and resting tone of the sphincter complex in profilometry was twice as high as in manometry due to reflexive contraction of a pelvic floor muscle, probably the EAS. With profilometry a positive correlation was found between age and sphincter length. Endosonographically assessed thickness of the EAS, puborectal muscle, and levator ani complex showed a significant correlation with age. However, no correlation was demonstrated between age and internal anal sphincter thickness. Thus, the development of the essential structures of the anal canal in children is age dependent. In addition, these measurements of normal physiology and anatomy of the anal canal provide the basis for detecting pathological conditions of the anorectal region in children.

Adolescent↗
PubMed1993

Substance P-induced contractions of the guinea-pig proximal colon through stimulation of post-junctional tachykinin NK1 receptors.

The effects of three tachykinin NK1 receptor antagonists and a tachykinin NK2 receptor antagonist against substance P-induced contractions of the guinea-pig proximal colon longitudinal muscle were investigated. Atropine, tetrodotoxin and phosphoramidon did not affect the concentration-response curve for substance P (pEC50 = 7.8). The tachykinin NK1 receptor antagonist, 2S,3S-cis-CP 96345, competitively inhibited the contractions due to substance P (pA2 = 8.5; constrained pA2 = 8.9), but at higher concentrations (> or = 3 x 10(-7) M), 2S,3S-cis-CP 96345 also depressed the concentration-response curve for methacholine. The species-selective tachykinin NK1 receptor antagonists, WIN 51708 and WIN 62577 (both 1 x 10(-6) M), and the tachykinin NK2 receptor antagonist, SR 48968 (3 x 10(-7) M), had no effect. It is concluded that substance P induces contractions through the stimulation of tachykinin NK1 receptors on the smooth muscle cells. In this preparation, tachykinin NK2 receptors do not seem to be involved in the contractile action of substance P.

Androstanes↗
PubMed1993

Cisapride and a structural analogue, R 76,186, are 5-hydroxytryptamine4 (5-HT4) receptor agonists on the guinea-pig colon ascendens.

UNLABELLED: The purpose of this study was to investigate whether the effects of cisapride and its close structural analogue R 76,186 on the isolated guinea-pig colon ascendens, are mediated through 5-HT4 receptors. Both cisapride and R 76,186 induced contractions in a concentration-dependent fashion, giving monophasic concentration-response curves (cisapride: EC50 = 1.1 x 10(-7) M, maximum effect = 40.3% of methacholine-induced (3 x 10(-7) M) contractions; R 76,186: EC50 = 2.4 x 10(-8) M, maximum effect = 52.1%). Blockade of either 5-HT2 or 5-HT3 receptors did not affect the responses to cisapride. However, tropisetron (in 5-HT4 receptor-blocking concentrations), and DAU 6285 and SDZ 205-557, two novel selective 5-HT4 receptor antagonists, depressed the concentration-response curve to cisapride (to about 50%), and the curve to R 76,186 was shifted to the right. The apparent pA2 values were 6.6 (tropisetron), 6.3 (DAU 6285), and 7.5 (SDZ 205-557). However, none of these antagonisms was purely competitive as higher concentrations of these antagonists depressed the curve to R 76,186. Desensitization of the 5-HT4 receptor with 5-methoxytryptamine (5-MeOT) inhibited the responses to cisapride, and abolished those to R 76,186. The contractions to cisapride and R 76,186 were sensitive to mutual antagonism, depressing their concentration-response curves. CONCLUSIONS: Both cisapride and R 76,186 mediate their contractile effects in the guinea-pig colon ascendens through agonism at the 5-HT4 receptor, though cisapride also uses a non-5-HT mechanism. R 76,186 is a selective and potent 5-HT4 receptor agonist.

4-Aminobenzoic Acid↗