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Biomedical subjects

M Classen

Publications and source records attributed to M Classen.

At least 307 records · Page 17Linked to original sources
PubMed1986

Effect of insulin on secretion of bombesin-like immunoreactivity and gastrin from the isolated rat stomach in response to acetylcholine, VIP and leucine-enkephalin.

Bombesin-like immunoreactivity (BLI), a putative peptidergic neurotransmitter of the gastrointestinal intrinsic nervous system is released from the isolated perfused rat stomach in response to the classical neurotransmitter acetylcholine and in response to other putative peptidergic neurotransmitters such as vasoactive intestinal peptide (VIP), peptide histidine isoleucine (PHI) or growth hormone releasing factor (GRF). The secretion of BLI is modulated not only by gastric factors such as the intragastric pH but also by changes of perfusate glucose concentrations indicating that alterations of carbohydrate metabolism might have an effect on gastric neuroendocrine regulation. Since previous studies have shown that insulin, the major regulatory hormone of glucose metabolism, reduces gastric somatostatin and glucagon secretion it was of interest to determine the effect of insulin on gastric BLI and gastrin secretion. The experiments were performed in the isolated perfused rat stomach model. The addition of porcine insulin to the perfusate at concentrations of 50 and 100 microU/ml had no effect on basal BLI and gastrin secretion. The infusion of acetylcholine (2 X 10(-6)M and 4 X 10(-6)M) elicited a stimulation of BLI and gastrin secretion which was not altered by the addition of insulin (100 microU/ml). On the other hand, significant effects of insulin were observed during administration of the two putative peptidergic neurotransmitters VIP and leu-enkephalin. The infusion of VIP at 10(-11)M and 10(-8)M had no effect on BLI and gastrin secretion in the absence of insulin, however, with the addition of insulin (100 microU/ml) the higher dose of VIP (10(-8)M) elicited a significant stimulation of BLI secretion while both doses of VIP (10(-11)M and 10(-8)M) significantly increased gastrin release. Similar to VIP the infusion of leu-enkephalin at doses of 10(-9)M and 10(-6)M had no effect on BLI and gastrin secretion in the absence of insulin. When insulin was added to the perfusate both doses of leu-enkephalin elicited a significant stimulation of BLI secretion while gastrin remained unchanged. The addition of the specific opiate receptor antagonist naloxone (10(-5)M) did not block the effect of leu-enkephalin in the presence of insulin. In addition the effect of naloxone was also examined during cholinergic stimulation. The addition of naloxone (10(-5)M) during the infusion of acetylcholine abolished the stimulatory effect on BLI secretion in the absence of insulin, whereas in the presence of insulin naloxone did not alter cholinergically-induced BLI secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗
PubMed1986

Calcium, calmodulin, and cyclic adenosine monophosphate modulate prostaglandin E2 release from isolated human gastric mucosal cells.

We studied prostaglandin E2 (PGE2) release from isolated cells of the human gastric mucosa. Mucosal cells were enzymatically isolated from biopsy specimens of human fundic mucosa. The results from these crude cell preparations were compared to those obtained in fractions with enriched (65-80%) or depleted parietal cell content (3-7%) which were prepared from gastric mucosa obtained at surgery. PGE2 release in the enriched parietal cell fractions exceeded that from crude or parietal cell depleted preparations 3- and 13-fold, respectively. However, despite this quantitative difference, all preparations responded similarly to the test agents. Newly synthesized PGE2 was not stored intracellularly but was released into the incubation medium. Release increased linearly for 30 min. Addition of the calcium ionophore A23187 enhanced PGE2 release 4- to 5-fold. The effect of A23187 required the presence of extracellular Ca2+ (10(-3) mol/liter). Assuming that A23187 alters Ca2+ flux in gastric cells as it does in other cell systems our data indicate that increased Ca2+ influx enhances PGE2 release. Since calmodulin is of importance for intracellular Ca2+ action, the calmodulin antagonists trifluoperazine and W7 were tested. Both antagonists inhibited PGE2 release by 65-85%, trifluoperazine being slightly more effective. Activation of the adenylate cyclase system by forskolin or direct addition of (Bu)2cAMP, a stable cAMP-analog, also inhibited PGE2 release. We conclude that PGE2 is released from parietal and from nonparietal cells of the human gastric mucosa, although the major quantity is released from the light density fraction that is enriched in parietal cells. In parietal and nonparietal cells Ca2+ is of importance in the regulation of gastric mucosal PGE2 release and calmodulin seems to mediate this intracellular action of Ca2+. cAMP inhibits PGE2-release from gastric cells.

Bucladesine↗
PubMed1986

Modulatory glucose effect on bombesin-like immunoreactivity and gastrin secretion from isolated perfused rat stomach.

Previous studies have demonstrated mostly inhibitory effects of elevated plasma glucose levels on gastric exo- and endocrine as well as motor functions. Because increased plasma glucose levels reduce vagal activity via the central nervous system, it remains unclear if glucose exerts a direct effect on gastric functions. Therefore, our study was designed to determine the effect of acute changes in glucose concentrations on the release of gastrin and bombesin-like immunoreactivity (BLI) from the isolated perfused rat stomach. Acute elevations of perfusate glucose from 100 to 200 mg/dl or from 100 to 300 mg/dl augmented BLI secretion significantly without affecting gastrin release. During an acute decrease from 200 to 30 mg/dl, the secretion of both peptides remained unchanged. When acetylcholine was administered to stimulate BLI and gastrin secretion, the elevation of perfusate glucose to 200 mg/dl and the decrease to 30 mg/dl attenuated BLI secretion, whereas gastrin secretion remained unchanged compared with the control experiments at 100 mg/dl glucose. On the other hand, the perfusion of vasoactive intestinal peptide (VIP) and Leu-enkephalin had no effect on BLI and gastrin secretion during 100 mg/dl glucose perfusion, but both peptides elicited a significant stimulatory effect on BLI secretion during a perfusate glucose concentration of 200 mg/dl without affecting gastrin secretion. In conclusion, our study demonstrates first that an acute increase of glucose augments basal BLI secretion. Second, cholinergically induced BLI secretion is attenuated by hypo- and hyperglycemia. Third, hyperglycemia augments BLI secretion in response to the neuropeptides VIP and Leu-enkephalin. Fourth, basal and stimulated gastrin secretion remains unchanged during acute alterations of perfusate glucose levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1986

Benign lesions of the upper GI tract by means of endoscopic ultrasonography.

In contrast to conventional ultrasound tomography endoscopic ultrasonography (EUS) allows an exact evaluation of the wall of the upper GI tract. The gastric and esophageal walls give a typical five-layer image presumably corresponding to the mucosa (two inner layers), submucosa (middle echogenic layer), muscularis propria (outer echo-poor layer), and serosa (outer echogenic layer). A thickening of the mucosa may be demonstrated in Ménétrier's disease. In patients with gastric antrum ulcers there is considerable thickening of the gastric wall, especially of the submucosa and muscularis. Benign gastric and esophageal submucosal tumors are easily localized between the different layers. They are easily distinguished from malignant processes by means of EUS. In patients with polypoid endoscopic aspect due to an impression from outside, a tumor can be easily excluded.

Endoscopy↗
PubMed1986

Endosonographic diagnosis of benign pancreatic and biliary lesions.

The transduodenal and transgastric route provides good access to the pancreas and to large parts of the biliary tract, and endosonography (ES) creates images of high-detail resolution. Of 87 patients examined, 33 had benign lesions of the pancreas and biliary tract. All of 12 patients with chronic calcifying pancreatitis were correctly diagnosed, and ES in addition displayed minute cysts that were missed with conventional imaging modalities. Two of three apudomas were seen with ES, and seven of eight common bile duct (CBD) stones could be identified. Adenomyosis of the papilla of Vater was missed in all of three cases. Although minor alterations of the gallbladder can be displayed by ES, benign lesions of this organ are at present not indications for ES, whereas changes in the terminal portion of the CBD are rewarding for ES examination. ES proved to be a useful morphological technique in the diagnosis of minor benign alterations of the pancreas and prepapillary stones.

Adult↗
PubMed1986

A rare source of occult gastrointestinal bleeding: jejunal filiae secondary to metastatic lung carcinoma.

A case of occult gastrointestinal bleeding due to jejunal metastases of a primary lung carcinoma in a 53-year-old man is reported. When after healing of a large gastric ulcer melena persisted, a subsequently performed double contrast enema of the small bowel revealed evidence of several jejunal tumors. This was confirmed by angiography of the superior mesenteric artery and computed tomography of the abdomen. After resection of the tumor-bearing jejunal loop, histological evaluation revealed metastases secondary to a large-cell bronchogenic carcinoma which had been resected 1 year previously.

Carcinoma, Bronchogenic↗
PubMed1986

Electronic endoscopy--fibres or chips?

The video endoscope represents a new generation of endoscopic instruments. The main feature is an intragastric CCD-chip transforming the optical impulses into electronic signals. The latter are transmitted without any optical fibre bundle, transformed by a video processor and visualized on a television screen. The present experience show drawbacks in respect to mechanical properties of the endoscopes, to reproduction of colors (esp. red) and photographic documentation. On the other hand the excellent image quality guarantees convenient handling for investigator, information for attending persons (doctors, nurses, students), improved conditions for documentation and control of quality. Although the video-endoscope is not replacing fibre endoscopes at present, further improvement will promote its general acceptance.

Endoscopes↗
PubMed1986

[New observations in a case of Cronkhite-Canada syndrome].

We report about a 76 years old patient with Cronkhite-Canada syndrome. The diagnosis has been found with the following clinical symptoms: diarrhea, anorexia, alopecia, and onychotrophia. Laboratory values: severe hypoproteinemia (total serum protein 4.3 g/dl, albumin 2.4 g/dl); endoscopical and radiological findings: a generalized polyposis which involved the whole intestine except the oesophagus. As far as we saw in our literature-overview of 55 patients with Cronkhite-Canada syndrome, this patient had for the first time a carcinoma of the urinary bladder and a Bricker operation 17 years before the onset of his disease. Further we remarked a lack in the resorption of the enterally administered thyroidal hormones. The progress was fatal despite a parenteral hyperalimentation and a treatment with antibiotics and glucocorticoids.

Aged↗
PubMed1985

[Endoscopic ultrasonic study of the esophagus].

Endoscopic ultrasonotomography opens a sonographic window to the organs of the mediastinum. With this technique all segments of the oesophagus can be sonographically investigated. Endosonographic investigations on 11 patients with oesophageal tumors and 3 patients with oesophageal varices showed that the diagnosis of oesophageal carcinoma and differentiation between malignant tumors and benign changes are possible. The spread of the tumor in the horizontal and vertical planes can be accurately determined with endoscopic ultrasonography. In addition, paraoesophageal lymph node metastases, as well as other lesions in the mediastinum, can be diagnosed. Ultrasonography of the oesophagus can be simplified by leaving out the optical system.

Carcinoma, Squamous Cell↗
PubMed1985

[Healing rates following omeprazole and ranitidine treatment of gastric ulcer. Results of a German multicenter study].

The effectiveness of omeprazole (20 mg orally each morning) or ranitidine (150 mg orally twice daily) in the treatment of gastric ulcer was compared in 184 out-patient in a randomized, endoscopically controlled multi-centre double-blind ("double dummy") trial. Healing rates with omeprazole after two, four and eight weeks were 43, 81 and 95%, respectively, those with ranitidine were 45, 80 and 90%, a statistically not significant difference. Independently of medication, small ulcers (less than 8 mm diameter) healed more quickly than larger ones. Ulcers in the body of the stomach responded poorest to both drugs. Smoking had no statistically significant effect on healing rate. Omeprazole and ranitidine had similarly favourable effects on symptoms. Neither side effects nor changes in biochemical parameters could be ascribed to omeprazole. Both drugs had equivalent effects on the healing of gastric ulcers in the stated dosages.

Adult↗
PubMed1985

[Rectoscopy: rigid or flexible? A comparative study].

The customary rigid rectoscope was compared prospectively, with a new, flexible one (prototypes of Olympus Opt. and Fuji) in each of 114 patients selected at random. Maximal depth of introduction was reached on average after 1 min with the rigid instruments, after 1 min 40 sec with the flexible one. Mean depth of introduction was 16 cm for the rigid and 33 cm for the flexible one. In 21 patients (18.4%) additional information was obtained with the flexible rectoscope. 80% of patients reported that the flexible instrument caused them no or only slight discomfort. Skill in using the flexible instrument can be quickly acquired.

Fiber Optic Technology↗
PubMed1985

[Short-term therapy of duodenal ulcer with omeprazole and ranitidine. Results of a German multicenter study].

In a randomized, endoscopically controlled double-blind trial the effectiveness of a single oral, morning dose of 40 mg omeprazole was compared with a twice daily oral dose of 150 mg ranitidine given to 334 ambulatory patients with duodenal ulcers. Under omeprazole 105 of 146 duodenal ulcers were demonstrated to have healed within 14 days (72%), compared with 95 of 160 (59%) on ranitidine. The difference is statistically significant (P = 0.0121). After 14 days smaller ulcers healed more quickly than large ones, regardless of the drug used: 80 of 110 with diameter 3-5 mm (73%); 48 of 90 with diameter more than 8 mm (53%). Smoking delayed healing [healing rate among non-smokers, 87 of 117 (74%); among smokers, 113 of 189 (60%)]. Healing rates among smokers receiving omeprazole and non-smokers receiving ranitidine were nearly identical. After 4 weeks, at 96 and 92% respectively, there was no difference in regard to healing rate. Both drugs had a similar influence on the symptoms. Thus, for the first time it has been demonstrated that omeprazole is superior to ranitidine after 14-day treatment of duodenal ulcer.

Adolescent↗