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Biomedical subjects

H Koop

Publications and source records attributed to H Koop.

At least 73 records · Page 4Linked to original sources
PubMed1990

Cholecystokinin release by gastric distension--an atropine-sensitive mechanism.

The effect of gastric distension on plasma cholecystokinin (CCK), pancreatic polypeptide (PP) and gastrin concentrations was investigated in healthy volunteers. Fundic and antral distension was achieved by balloons attached to a gastric tube and inflated with 300 and 600 ml and 100 and 200 ml of air for fundic and antral distension, respectively. Gastric juice was continuously aspirated. Fundic distension was additionally studied during a concomitant intravenous infusion of atropine (5 micrograms/kg/h) or a bolus injection of propranolol (2 mg). Fundic distension with 300 ml caused a significant increase in PP release (+17% above basal). Distension with 600 ml significantly stimulated CCK (+81%), gastrin (+31%) and PP output (+74%) over 30 min. Atropine completely blocked PP release and almost abolished CCK release, whereas gastrin output was enhanced. Propranolol did not prevent CCK release induced by fundic distension, whereas gastrin and PP responses were diminished. Antral distension did not cause any significant changes in hormone response. In conclusion, we demonstrated a gastric phase of CCK release which is atropine sensitive, but not influenced by propranolol.

Adult↗
PubMed1990

Effect of glucagon-like peptide-1 on gastric somatostatin and gastrin secretion in the rat.

The effect of glucagon-like peptide-1 (GLP-1) amide on gastric somatostatin and gastrin secretion was investigated in the isolated, vascularly perfused rat stomach preparation. GLP-1 (7-36) amide, 10(-12) to 10(-7)M, dose-dependently increased gastric somatostatin release, achieving maximal stimulation (314 +/- 15% above basal) at the highest dose. The somatostatin response to 10(-8)M GLP-1 (7-36) amide was not affected by concomitant perfusion with tetrodotoxin. GLP-1 (1-36) amide did not affect somatostatin release. Both basal and acetylcholine-stimulated gastrin were inhibited by GLP-1 (7-36) amide but were not influenced by GLP-1 (1-36) amide. In is concluded that GLP-1 (7-36) amide is the biologically effective peptide that stimulates gastric somatostatin and inhibits gastrin secretion, probably via non-neural pathways. GLP-1 (7-36) amide-induced inhibition of gastric acid secretion may, at least in part, be due to enhanced somatostatin and/or decreased gastrin release.

Animals↗
PubMed1990

Effect of peptide YY on gastric acid secretion, gastrin and somatostatin release in the rat.

The influence of PYY on stimulated gastric acid secretion and the possible role of gastric somatostatin was measured in rats. PYY, infused intravenously at a dose of 800 pmol/kg/h, reduced pentagastrin (20.8 nmol/kg/h) stimulated gastric acid secretion by 34 +/- 3%, whereas in controls acid secretion remained constant throughout the 90 min observation period. In a second series the effect of PYY on the endogenous gastric somatostatin-like immunoreactivity and gastrin-release was tested in the isolated, vascularly perfused rat stomach. PYY perfused at concentrations of 10 pM to 100 nM did not change either somatostatin or gastrin secretion from the rat stomach in vitro. The study shows that PYY suppressed acid secretion in the rat. Endogenous somatostatin or gastrin is unlikely to mediate the inhibitory effect of PYY on acid production.

Animals↗
PubMed1990

Effect of omeprazole on serum gastrin levels: influence of age and sex.

Serum gastrin levels were determined in 120 consecutive patients (43 females, 77 males) with peptic disease 24 h post dose after 4 weeks continuous omeprazole (40 mg daily) treatment. Serum gastrin levels were elevated in 33 (28%) but exceeded the twice normal range in only 6 patients (5%). Age and sex did not influence the magnitude of gastrin levels. Gastrin increments induced by omeprazole compared to pretreatment with H2-blockers in 60 cases were similar in both males (42 +/- 10 pg/ml) and females (44 +/- 9 pg/ml). It is concluded that the magnitude of gastrin increases observed during omeprazole therapy are small and independent of age and sex.

Adolescent↗
PubMed1989

Role of circulating catecholamines in the control of pancreatic polypeptide and gastrin release.

The influence of circulating catecholamines on the release of pancreatic polypeptide (PP) and gastrin was studied in volunteers. Physical exercise increased plasma epinephrine by 374 +/- 123% and plasma norepinephrine by 167 +/- 30%, but plasma PP concentrations remained unchanged during standardized bicycle ergometry. Immediately after cessation of exercise catecholamine levels decreased rapidly, whereas PP concentrations increased by 55%. In a second series, epinephrine infusion (5, 25, and 75 ng.kg-1.min-1) increased epinephrine levels by 38 +/- 12, 331 +/- 69, and 1229 +/- 131%, respectively, whilst norepinephrine was unaffected. Neither during nor after catecholamine infusion PP secretion was affected. Gastrin release increased by a maximum of 85 +/- 38% (at epinephrine 75 ng.kg-1.min-1). It is concluded, that (1) changes in circulating adrenaline do not significantly influence PP secretion in man; (2) the PP increase immediately following physical exercise cannot be attributed to a rapid fall of catecholamine levels; (3) endogenous catecholamines are of minor importance in the control of gastrin secretion.

Adult↗
PubMed1989

A unique case of intravenous injection of fungal "pancreatic" enzymes causing shock and proteolysis of haemostatic proteins.

A 20-year-old man on oral substitution of pancreatic enzymes after hemipancreatectomy injected an enzyme preparation of fungal origin intravenously after dissolving it in water. Within a few hours chills, headache, nausea and vomiting, fever of 40.8 degrees C, and shock occurred. The acute illness might have been caused by bacteremia, an anaphylactic reaction, or by direct activation of humoral or cellular mediators by the fungal enzymes. A haemostatic disturbance, particularly a drop in plasminogen, was observed. In vitro, the fungal enzyme preparation stimulated elastase release from isolated neutrophils and eliminated plasmatic inhibitors and plasminogen in normal plasma and whole blood. Human neutrophil elastase complexed to alpha 1-antitrypsin was increased in the patient's plasma, while the levels of the complexes thrombin-antithrombinIII and plasmin-alpha 2-antiplasmin, indicating recent coagulation or fibrinolysis, respectively, were not elevated. Thus, an activation of the neutrophils with release of elastase might have contributed to the observed coagulation disturbances.

Adult↗
PubMed1989

Irradiation-induced duodenal ulcer disease refractory to ranitidine: healing by omeprazole.

In two patients duodenal ulcer refractory to high dose H2-blocker treatment started several months after irradiation therapy following right nephrectomy because of renal adenocarcinoma. Established antiulcer drugs like ranitidine, famotidine, sucralfate, pirenzepine, and antacids alone or in combination were unable to control ulcer pain and failed to induce ulcer healing. Initiation of omeprazole treatment at dosages to produce complete achlorhydria were necessary for ulcer healing and maintenance therapy. We suggest that (a) irradiation may cause duodenal ulcer disease indistinguishable from idiopathic duodenal ulcer; (b) radiation-induced ulcers in the duodenal bulb are refractory to various antiulcer drugs but may heal after administration of omeprazole in dosages that completely suppress acid secretion.

Aged↗
PubMed1989

Degradation of vasoactive intestinal peptide by isolated, ventilated, and perfused rat lungs.

The degradation of vasoactive intestinal peptide (VIP) was studied using an isolated perfused rat lung model. 125iodine labelled VIP (125I-VIP) was used as a tracer. VIP was cleared from the perfusate by a single lung passage up to concentrations of 1 nmol l-1. The clearance rate was decreased at higher concentrations of VIP. VIP was taken up by the lung tissue and the cleavage products were re-extruded into the perfusate. The time delay of re-extrusion was increased at starting concentrations of VIP exceeding 1 nmol l-1 and in the presence of the lysosomal inhibitor chloroquine. After a bolus of 9 pmol or 40 nmol 125I-VIP into the pulmonary artery catheter 6.3 pmol or 2920 pmol, respectively, were bound by the lung. Most of the radioactive material was extruded within 25 min and consisted of low molecular weight 125I-labelled degradation products. We conclude that the receptors for VIP in the alveolar capillaries are of high affinity and capacity to extract VIP from the circulation and that lysosomes may be involved in the degradation. The degradation products are of low molecular weight.

Animals↗
PubMed1989

Omeprazole: long-term safety.

Based on the experience from more than 10,000 individuals omeprazole has been found to be safe and is well tolerated. Side effects are few and do not differ from those observed during H2-blocker treatment. Effects on endocrine cells observed in animals during toxicological studies include increase of antral G cells, decrease of antral D cells and increase of fundic ECL cells. The increase of G cells and the decrease of D cells is the consequence of achlorhydria achieved by very high omeprazole dosages and results in hypergastrinaemia. Hypergastrinaemia is responsible for ECL cell hyperplasia. Lifelong hypergastrinaemia in rats has been found to induce carcinoid tumours. This gastrin-carcinoid sequence is unlikely to occur in man with an omeprazole dosage recommended for treatment of peptic diseases. Therapeutic doses in man do not produce complete achlorhydria. Therefore, serum gastrin levels increase in man during omeprazole treatment only moderately and are similar in magnitude as after selective proximal vagotomy. Available results on gastric endocrine cells in patients treated with omeprazole for up to 2 years could not demonstrate significant changes in G, D and ECL cell densities. It is concluded that omeprazole is, in man, as safe as H2 blockers if administered in doses recommended for treatment of peptic diseases.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1989

Influence of chronic rioprostil treatment on gastric endocrine function.

The influence of 4 weeks of treatment with the prostaglandin E1 analogue, rioprostil, 300 micrograms b.i.d., or placebo, on gastric endocrine function is tested in healthy male volunteers. Basal serum gastrin levels and postprandial gastrin output are unchanged after treatment with rioprostil. Similarly, plasma pancreatic polypeptide levels are unaffected. Antral gastrin tissue concentrations as well as antral somatostatin concentration and volume densities of antral G-cells and D-cells are unchanged. Neither basal nor pentagastrin-stimulated gastric acid secretion after rioprostil therapy differ from pretreatment values. Rioprostil, given in a dose of 100 micrograms b.i.d. to rats for 1 week significantly increases antral mucosal height but has no influence on the mucosal concentrations and cell densities of the gastric peptides, gastrin and somatostatin. It is concluded that rioprostil in the dose used does not affect the endocrine stomach after 4-weeks' administration at a dose of 300 micrograms b.i.d.

Adult↗
PubMed1989

Do bile acids exert a negative feedback control of cholecystokinin release?

The influence of intraduodenal bile deficiency due to chronic bile duct obstruction and acute exogenous administration of bile acids on plasma cholecystokinin (CCK) and pancreatic polypeptide (PP) was investigated. Fourteen patients with tumor-induced bile duct stenosis and five healthy volunteers were given a liquid test meal. Four of the patients had a simultaneous pancreatic duct stenosis. On another day 4 g chenodeoxycholic acid were administered concomitantly with the liquid test meal in six of the patients and all controls. Basal and meal-stimulated plasma CCK did not differ between patients and controls. A pancreatic duct stenosis, which was associated with diminished plasma PP concentrations, had no influence on plasma CCK release. Exogenous bile acids significantly reduced the postprandial CCK response in both groups. Bile-induced inhibition was significantly greater in patients than in controls (75 +/- 7% and 44 +/- 11%, respectively; p less than 0.05). It is concluded that intraduodenal bile is an important modulator of the postprandial secretory activity of the CCK cell. Although chronic intraduodenal bile acid reduction in tumor-induced biliary duct stenosis did not influence plasma CCK levels, a negative feedback control of plasma CCK by acute bile acid administration could be demonstrated.

Adult↗
PubMed1988

[Segmental colonic stenosis in intestinal metastasis of breast carcinoma. A contribution to the differential diagnosis of colitis].

Four years after mastectomy for a scirrhous carcinoma a 71-year-old woman developed diarrhoea. Crohn's disease was suspected. At endoscopy a stenosis of the sigmoid colon was found which could not be passed: the mucosa was normal looking. Gastrointestinal radiography revealed segmental subtotal stenoses of the colon with linitis plastica, typical for tumour-caused infiltration, as well as indentations in the small intestine by mesenteric metastases. The diagnosis was confirmed by computed tomography and, finally, operation. Chemotherapy failed to produce any regression of the colon stenoses, and the patient died from mechanical ileus. In case of a similar history and colon stenoses of uncertain aetiology the possibility of intestinal metastases should be considered in the differential diagnosis.

Adenocarcinoma, Scirrhous↗
PubMed1988

Plasma CCK levels in patients with pancreatic insufficiency.

After stimulation with a Lundh test meal, plasma concentrations of cholecystokinin (CCK) and pancreatic polypeptide (PP) and output of pancreatic enzymes were measured in 33 patients with exocrine pancreatic insufficiency and 26 healthy subjects. Patients with impairment of pancreatic function were subdivided into those with moderate and severe insufficiency. Plasma CCK and PP were measured by radioimmunoassay. Fasting plasma CCK in patients with pancreatic insufficiency (5.8 +/- 1.1 pmol/liter) did not differ significantly from controls (4.2 +/- 0.6 pmol/liter). After endogenous stimulation with a Lundh meal, plasma CCK increased in both groups without significant differences over 2 hr. Basal and stimulated plasma levels of pancreatic polypeptide (PP) were markedly decreased only in patients with severe pancreatic insufficiency. Our results demonstrate that basal and meal-stimulated CCK levels in patients with pancreatic insufficiency do not differ from controls. Furthermore the extent of functional impairment of the exocrine pancreas did not influence basal and postprandial CCK release.

Adult↗