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H Gregersen

Publications and source records attributed to H Gregersen.

At least 37 records · Page 2Linked to original sources
PubMed1994

Biomechanical properties of the oesophagus damaged by endoscopic sclerotherapy. An impedance planimetric study in minipigs.

BACKGROUND: The aims of the present study were to evaluate, by means of impedance plainmetry, regional differences in biomechanical properties in the normal oesophagus and the oesophagus damaged by sclerotherapy. METHODS: Four minipigs underwent a weekly session of sclerotherapy for 4 weeks. Impedance planimetry was performed before the first session of sclerotherapy and 1 week after the last session of sclerotherapy. Investigations were performed by stepwise pressure-induced balloon distensions with concomitant measurements of pressure and luminal cross-sectional area (CSA) in the oesophagus 5 and 10 cm above the gastro-oesophageal junction (GEJ). RESULTS: The normal oesophagus had significantly larger CSAs 5 cm than 10 cm above the GEJ (P < 0.05). Endoscopic sclerotherapy entailed an inversion (P < 0.05) of the normal oesophageal configuration, with narrowing 5 cm above the GEJ (P < 0.05) and increased CSAs 10 cm above the GEJ (P < 0.05). CONCLUSIONS: Regional differences in CSA occur in the normal oesophagus, and sclerotherapy produces profound changes in the oesophageal configuration.

Animals↗
PubMed1993

[Experimental gastrointestinal motility].

Gastrointestinal motility is a major field of research today; however, despite there being a huge amount of available data in the literature, its exact role as a diagnostic tool has yet to be defined. The purpose of this paper is to describe some of the existing experimental models and methods for conducting motility studies.

Animals↗
PubMed1993

Biomechanical characteristics of the human esophagus.

Biomechanical wall properties of the human esophagus were studied. A probe, with a balloon designed for simultaneous measurement of cross-sectional area and intraluminal pressure, was placed in the esophagus 30 cm from the incisors. Tone was not detected before inflation of the balloon. When the balloon was inflated stepwise with pressures up to 40 cm H2O (30.7 mmHg), measurement of cross-sectional area allowed calculation of distensibility and circumferential wall tension. Balloon cross-sectional area increased linearly with increased balloon pressure. Balloon distension induced contractions, both proximal to the balloon and at the site of distension, at a balloon pressure of about 15 cm H2O (11.5 mm Hg). The cross-sectional area for the threshold for distension induced contractions was 153 +/- 12 mm2 (diameter 14 mm). At the onset of these contractions, the contraction force was 15-20 cm H2O (11.5-15.3 mm Hg) and it increased to 47-58 cm H2O (36.1-44 mm Hg) at a balloon pressure of 20-40 cm H2O (15.3-30.7 mm Hg). Circumferential wall tension increased with increasing intraluminal pressure in an almost exponential manner. The pressure elastic modulus increased steeply at lower balloon pressures (10-20 cm H2O) (7.7-11.5 mm Hg), but at higher balloon pressures (20-40 cm H2O) (15.3-30.7 mm Hg) this increase was less. The circumferential wall tension and wall stiffness of the human esophagus increased with increasing balloon pressure and cross-sectional area. When a threshold is reached, distension induced contractions both proximal and distal to the balloon and at the distension site.

Adult↗
PubMed1993

Biomechanical wall properties of the human rectum. A study with impedance planimetry.

Biomechanical properties of the rectal wall were studied in 17 healthy adult volunteers (nine men and eight women). With impedance planimetry it is possible to obtain simultaneous measurements of pressure and rectal cross sectional area (CSA) during balloon inflations. Rectal distensions were done with an intraluminal balloon using specified pressures up to 40 cmH2O above baseline rectal pressure. Balloon inflation elicited a phase of rapid increase in rectal CSA followed by a phase of slow increase until a steady state was reached. Steady state occurred within 67 to 140 seconds with the shortest period at the highest distension pressures. Steady state rectal CSA values had a non-linear relation to increasing distension pressure. Rectal CSA values in women showed a tendency of being slightly higher than male values at all pressure steps with a significant difference at 3 and 5 cm H2O. Biomechanical parameters were calculated from rectal CSA pressure relations. Circumferential wall tension increased in a linear way. Rectal compliance decreased in a non-linear way with no further decline between 30 and 40 cmH2O. The pressure elastic modulus increased steeply until a distension pressure of 35 cmH2O with no further increase to 40 cmH2O. This suggests that rectal tone is reduced as the muscle fails to resist further distension at 35 cmH2O and higher pressures. Impedance planimetry offers new possibilities for investigation of anorectal physiology through the study of segmental biomechanical wall properties of the human rectum.

Adult↗
PubMed1992

Effects of noradrenaline and galanin on duodenal motility in the isolated perfused porcine pancreatico-duodenal block.

The influence of neurotransmitters on gastrointestinal motility is different in different segments of the gastrointestinal tract. To clarify the regulation of duodenal motility, the aim of the present study was to investigate the effects of alpha-adrenoceptor agonism and blockade and of galanin on duodenal motility. The study was undertaken in the isolated perfused porcine pancreatico-duodenal block. The agents under investigation were administered arterially. Duodenal motility was measured by means of a low-compliance perfusion system using an intraluminal catheter. In addition the concentration of galanin was measured in the portal effluent. We found that spontaneous motility was abolished by noradrenaline by an effect that was counteracted by the alpha 2-adrenoceptor antagonist idazoxan. In contrast, the selective alpha 1-adrenoceptor antagonist prazosin did not influence the effect of noradrenaline. Galanin, like noradrenaline, abolished duodenal motility. Furthermore, the concentration of galanin in the portal effluent was decreased by noradrenaline by an alpha 2-adrenoceptor mediated mechanism. We conclude that alpha 2-adrenoceptor activation and galanin inhibit duodenal motility and that the release of galanin from the pancreatico-duodenal preparation is reduced by alpha 2-adrenoceptors.

Adrenergic alpha-Antagonists↗
PubMed1992

Biomechanical wall properties and collagen content in the partially obstructed opossum esophagus.

A specially designed probe was used to investigate biomechanical wall properties of the esophagus in opossums with distal esophageal banding. A balloon was stepwise inflated and deflated 6 cm above the lower esophageal sphincter before the banding and at 2 weeks postoperatively. After animals were killed, collagen content of the esophageal wall was determined. Preoperatively, cross-sectional area and wall tension at maximal inflation of the balloon, compliance, and hysteresis were 108.04 +/- 7.23 mm2, 5.8 +/- 0.3 cm H2O/m, 0.664 +/- 0.081 mm2/cm H2O, and 101.14 +/- 18.89 mm2, respectively. Postoperatively, the parameters increased to 357.45 +/- 54.22 mm2 (P < 0.001), 10.5 +/- 1.4 cm H2O/m (P < 0.001), 2.402 +/- 0.420 mm2/cm H2O (P < 0.001), and 225.86 +/- 44.56 mm2 (P < 0.05), respectively. The collagen content was 0.065 +/- 0.004 and 0.104 +/- 0.009 mg/mg dry defatted weight in the mid and distal normal esophagus, respectively, compared with 0.110 +/- 0.012 and 0.121 +/- 0.012 mg/mg in the banded group (P < 0.05 in the middle part). A positive correlation was shown between the maximal cross-sectional area and the collagen content in the mid-esophagus (P < 0.05). In conclusion, biomechanical wall properties were altered significantly, indicating dilatation and decreased ability of the esophageal wall to resist intraluminal pressure.

Animals↗
PubMed1992

Biomechanical properties of duodenal wall and duodenal tone during phase I and phase II of the MMC.

We used a new method, impedance planimetry, to look at variations in compliance, tone, and distension-induced peristaltic activity during phase I and phase II of the migrating myoelectric complex (MMC) in the human duodenum. A balloon was inflated stepwise with pressures up to 30 cmH2O in the duodenum, while the pressure and balloon cross-sectional area (CSA) were measured simultaneously. The biomechanical wall parameters were calculated from these measurements. Nine duodenal phase IIIs were recorded in six subjects. A balloon pressure of 20 cmH2O induced a smaller CSA in early phase I [266 (236-324) mm2] than in late phase II [385 (276-474) mm2] (P < 0.05). Balloon distensions elicited no contractions in phase I, whereas they increased contractile activity 60% (P < 0.05) proximal to the balloon and 4% distal to the balloon in late phase II. Step distensions in phase I with balloon pressures between 10 and 30 cmH2O increased the CSA from 40 (30-81) to 645 (603-704) mm2. It increased circumferential wall tension from 35 (28-63) to 429 (402-466) mm x cmH2O and the pressure elastic modulus from 9.7 (9.0-14.7) to 33.8 (27.6-33.8) cmH2O, respectively. Thus compliance differs from phase I to phase II. This is most likely caused by increased smooth muscle tone during phase I. Duodenal wall stiffness increases with the balloon pressure applied.

Adult↗
PubMed1992

Characteristics of spontaneous and evoked motility in the isolated perfused porcine duodenum.

The aims of the study were to evaluate characteristics of spontaneous motility and of the ascending excitatory peristaltic reflex (AEPR) and intraluminal cross-sectional area in the isolated perfused porcine duodenum. The parameters were measured by an intraluminal catheter by use of the perfused side-hole technique and impedance planimetry. Respiratory parameters such as pH and oxygen consumption and the arterial perfusion pressure were monitored and did not vary significantly throughout the study time. Spontaneous motility was intense at the beginning but declined and disappeared within 45-90 min. It was abolished by atropine, epinephrine, and UK-14,304 (an alpha 2-adrenoceptor agonist). Secondary motility was evoked by intraluminal balloon distensions by raising the balloon pressure to 1.5 kPa for 1-min periods. Reproducible results regarding the AEPR, external balloon diameters to elicit the AEPR, and intraluminal cross-sectional area were obtained. The order of potency (pD2 values) for inhibition of the AEPR was the selective M3-receptor antagonist 4-DAMP greater than atropine greater than the selective M2-receptor antagonist AFDX-116 greater than the selective M1-receptor antagonist pirenzepine greater than hexamethonium. 4-DAMP was 16 and 29 times more potent than AFDX-116 (P less than 0.02) and pirenzepine (P less than 0.02). None of the drugs altered the intraluminal cross-sectional area during the balloon distensions. The model provides the opportunity for physiological and pharmacological studies of duodenal motility and duodenal cross-sectional area devoid of extrinsic neural and endocrine effects. The abolishment of the AEPR by atropine is caused by blockade of the M3-receptor in the porcine duodenum.

Animals↗
PubMed1992

Calcitonin gene-related peptide: effect on contractile activity and luminal cross-sectional area in the isolated, perfused porcine ileum.

Because calcitonin gene-related peptide (CGRP) is an abundant peptide in the enteric nervous system we studied the effect of intra-arterial infusions of synthetic human CGRP I in concentrations from 10(-10) to 10(-8) mol/l on contractile activity and luminal cross-sectional area in the isolated perfused porcine ileum, using manometry and impedance planimetry. The frequency of the basal contractile activity was 0.37 +/- 0.1 contractions per minute. CGRP induced phasic contractions, which at the highest dose were superimposed on tonic contractions, as determined by measurement of luminal cross-sectional area. The frequency of contractions dose-dependently increased to approximately 10/min at 10(-8) mol/l CGRP. The amplitude of contractions increased from a maximum of 35 cm H2O to 51 +/- 3 at 5 x 10(-9) mol/l CGRP and 52 +/- 6 cm H2O at 10(-8) mol/l CGRP. After the termination of CGRP infusion at the highest dose a short phase of up to 5 min with strong tonic contraction was observed. No phasic activity was detected by manometry during this phase. In conclusion, CGRP dose-dependently increased contractile activity in the pig ileum. CGRP may therefore participate in the regulation of small-intestinal motility in the pig.

Animals↗
PubMed1992

Galanin inhibits tolbutamide-stimulated insulin secretion in the perfused pig pancreas.

The neuropeptide galanin is known to inhibit insulin secretion in a variety of species. However, controversies exist regarding its action on insulin secretion in the perfused pig pancreas, since both inhibitory and stimulatory effects have been described. We therefore perfused the isolated porcine pancreatico-duodenal block with galanin (100 nmol/l) in the presence of 5 or 15 mmol/l glucose or with 5 mmol/l glucose and 10 mumol/l tolbutamide. We found that at this dose level, galanin did not affect insulin secretion stimulated by glucose alone. In contrast, galanin clearly suppressed tolbutamide-stimulated insulin secretion. Hence, we conclude that galanin has a weak influence on insulin secretion in the pig pancreas, being unable to inhibit glucose-stimulated insulin secretion at the dose level of 100 nmol/l. However, when active, galanin clearly inhibits insulin secretion also in the pig pancreas.

Animals↗
PubMed1991

An alpha 1-adrenoceptor-sensitive mechanism is responsible for the adrenergic inhibition of insulin secretion in the pig pancreas.

The alpha-adrenoceptor subtype mediating inhibition of insulin secretion in the pig was examined in an isolated pancreas preparation perfused with 5 mM glucose. It was found that noradrenaline and the alpha 1-adrenoceptor agonist phenylephrine, but not the alpha 2-adrenoceptor agonist UK 14,304, inhibited insulin secretion. The effect of noradrenaline was abolished by the alpha 1-adrenoceptor antagonist prazosin but was not affected by the alpha 2-adrenoceptor antagonist idazoxan. The inhibitory effect of phenylephrine was also inhibited by prazosin. Thus, in the pig, the alpha-adrenoceptor subtype inhibiting insulin secretion is of the alpha 1-type, which is different from the subtype involved in other species.

Adrenergic alpha-Agonists↗
PubMed1991

Involvement of thin afferents in carpal tunnel syndrome: evaluated quantitatively by argon laser stimulation.

The thin afferent nerves were tested quantitatively by determining the thresholds of warmth and pricking pain to argon laser stimulation and by measuring the brain potentials related to pricking pain. In 27 patients with electrophysiologically verified carpal tunnel syndrome these parameters were measured from fingers 3 and 5 on both hands. All patients had had sensory symptoms ranging from 3 months to 25 years. Both the thresholds were elevated (P less than 0.05) at finger 3 compared to measurements from finger 5, and compared to finger 3 in a group of 39 controls. Four patients with symptoms for more than 7 years had thresholds below the control values. The power of the pain-evoked brain potentials elicited from finger 3 was lower (P less than 0.05) compared to finger 5, and compared to the control group (P less than 0.01). No correlations were found between the measured parameters and the clinical electrophysiological investigation. The findings support previous assumptions that chronic low-force compressions cause impairment of intraneural microcirculation, and hence can affect the function of the thin afferents.

Adolescent↗
PubMed1991

A time-dependent study of passive esophageal wall properties and collagen content in rabbits with esophageal varices.

The passive biomechanical wall properties of the esophagus were studied in rabbits with esophageal varices and controls using a four-electrode impedance technique. Stepwise pressure inflation and deflation was done for analysis of esophageal cross-sectional area, compliance, and hysteresis monthly during six months. At sacrifice, the esophageal collagen content was determined. A small but statistically insignificant increase in compliance was observed during the six-month observation period in both groups. No differences were observed between the groups (P greater than 0.3). No change in hysteresis was observed in either group. The group with esophageal varices had significantly higher collagen content in the distal esophagus when compared to controls (P less than 0.05). No difference was demonstrated in the proximal part. No correlation was demonstrated between the collagen content and esophageal compliance. The study demonstrated that the method allows measurement of luminal cross-sectional area and tissue elasticity. No relationship was found, however, between the collagen content and compliance of the rabbit esophagus.

Animals↗
PubMed1991

Diurnal variation of plasma atrial natriuretic peptide in normals and patients with enuresis nocturna.

The circadian variation of plasma atrial natriuretic peptide (ANP) in relation to urinary excretion of sodium (UNa) and potassium (UK) as well as clearance of creatinine (Ccrea) was assessed in 15 juvenile patients with enuresis nocturna and compared with 11 age-, sex-, and weight-matched normal subjects. Normal juveniles showed a highly significant diurnal variation (p less than 0.001) of plasma ANP with diurnal peak levels at midnight (0000 hours) and minimum levels at 0400 hours. Enuretic patients showed a similar diurnal rhythmicity with normal levels during day and night. In normals both UNa and UK showed significant diurnal rhythmicity with a marked reduction from daytime to night-time. Although the total diurnal excretions of UNa and UK were similar to normals, patients with enuresis showed abnormal diurnal variation in both UNa (p less than 0.05) and UK (p less than 0.01). The abnormal circadian rhythm of UNa and UK in enuretics seemed to be caused by abnormal tubular handling as similar abnormalities were found in the fractional excretions and as the circadian variation of Ccrea was normal. Especially during the first hours of sleep (2200 hours to 0000 hours), the patients showed polyuria (230 +/- 138 ml vs 116 +/- 58 ml, p less than 0.01), natriuresis (20.9 +/- 16.3 mmol l-1 vs 10.7 +/- 6.8 mmol l-1, p less than 0.01), and kaliuresis (7.3 +/- 6.3 mmol l-1 vs 3.7 +/- 2.3 mmol l-1, p less than 0.05), despite normal levels of plasma ANP. In conclusion, the study describes the diurnal variation of plasma ANP in relation to urinary excretion of sodium and potassium in a juvenile normal population. Patients with nocturnal enuresis show abnormal diurnal rhythmicity in the urinary excretion of sodium and potassium that is not correlated to the plasma levels of ANP.

Adolescent↗
PubMed1991

The role of the L-arginine-nitric oxide pathway in relaxation of the opossum lower oesophageal sphincter.

1. The role of the L-arginine-nitric oxide pathway in lower oesophageal sphincter (LOS) relaxation and oesophageal peristalsis was investigated. 2. Twenty four adult opossums were anaesthetized and the right vagus nerve was isolated in the neck and sectioned. Electrical stimulation, applied to the peripheral end of the nerve, resulted in a frequency-dependent relaxation of the LOS, and peristaltic and non-peristaltic contractions in the oesophageal body. 3. N omega-nitro-L-arginine (L-NNA, 10(-8)-10(-5) mol kg-1), an inhibitor of the L-arginine-nitric oxide pathway, inhibited LOS relaxation in a dose-dependent manner, but did not affect resting LOS pressure. At the highest dose of L-NNA no relaxation of the LOS was elicited in response to vagal stimulation. The effect of L-NNA, (10(-5) mol kg-1) was fully reversed by infusion of 10(-4) mol kg-1 L-arginine. Peristaltic velocity and amplitude of contractions in the oesophageal body were unaffected by L-NNA. 4. Infusion of sodium nitroprusside reduced LOS pressure to zero, and the drug was equally potent in control animals (-log ED50:8.1 +/- 0.2 mol kg-1) and in animals pretreated with L-NNA (-log ED50:8.2 +/- 0.3 mol kg-1). This suggests that the effect of L-NNA was not directly on guanylate cyclase. 5. A significant elevation of blood pressure was recorded after administration of L-NNA (10(-5) mol kg-1). 6. It is suggested that the L-arginine-nitric oxide pathway plays an important functional role for relaxation of the LOS, but not for oesophageal peristalsis. Whether the active substance is nitric oxide or a related nitroso-compound remains to be settled.

Animals↗
PubMed1991

Experimental gastrointestinal motility: where to go.

Gastrointestinal motility is a major field of research. However, despite a huge amount of data available in the literature, its exact role has yet to be defined. This paper deals with the choice of animal research models for motility studies.

Animals↗
PubMed1991

Impedance planimetry: a new approach to biomechanical intestinal wall properties.

This paper surveys impedance planimetry, a technique based on the measurement of electrical impedance for estimation of active and passive biomechanical wall properties of the intact intestine. The paper mainly concerns methodological aspects of the recording technique and possible sources of error. Furthermore, the historical background concerning developments of the technique and physiological results during the last two decades are described.

Animals↗