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Biomedical subjects

M Classen

Publications and source records attributed to M Classen.

At least 289 records · Page 16Linked to original sources
PubMed1988

Effect of somatostatin on skin lesions and concentrations of plasma amino acids in a patient with glucagonoma-syndrome.

A case of glucagonoma syndrome in a 58-year-old male patient who had the typical skin lesions associated with severe hypoaminoacidemia is described. The decrease in amino acids has been proposed to be causally related to the dermatosis. Furthermore, it has been shown previously that somatostatin rapidly improves skin lesions in glucagonoma patients. Therefore, plasma amino acid levels were determined before and during an infusion of somatostatin prior to surgical removal of the tumor in the tail of the pancreas. During somatostatin infusion in combination with total parenteral nutrition, 10 out of 22 amino acids were in the normal range. Thus it seems unlikely that normalization of amino acid levels is responsible for the rapid improvement in skin lesions in glucagonoma patients. On the other hand it cannot be excluded that partial normalization of amino acids contributed to the observed healing process. Nevertheless, somatostatin administered prior to surgery is a useful therapeutic regimen in these patients.

Adenoma, Islet Cell↗
PubMed1988

Effect of atrial peptide on gastric acid secretion in rats.

The effect of synthetic rat atriopeptin (AP) II was examined on basal, vagally and carbachol-induced gastric acid secretion in anesthetized rats. AP II infusion, at stepwise increasing doses of 2, 20 and 100 ng/kg/min, had no effect on basal acid secretion. At doses of 2 and 20 ng/kg/min, AP II augmented vagally induced acid secretion significantly. The secretory response to vagal stimulation + AP II 20 ng/kg/min was completely abolished by atropine. In contrast a higher dose of AP II (50 ng/kg/h) reduced vagally induced acid secretion significantly. This dose of AP II also reduced acid secretion during direct cholinergic stimulation by carbachol, while the lower dose of 20 ng/kg/min had no effect on carbachol-induced acid secretion. The present data demonstrate for the first time an effect of atrial peptide on gastric acid secretion. At lower doses AP II augments the vagal influence on parietal cell function perhaps by augmenting vagally induced acetylcholine release. At higher doses AP II exerts an inhibitory effect on parietal cell function during vagally and carbachol-induced acid secretion, suggesting different and as yet unknown mechanisms of action. These results raise the possibility that the heart can exert a hormonally mediated influence on the regulation of gastric acid secretion.

Animals↗
PubMed1988

Antral mucosal bile acids in two types of chronic atrophic gastritis.

Bile acids may damage the gastric mucosa, and they are cocarcinogenic in experimental colonic and gastric cancer. Chronic atrophic gastritis (CAG) and chronic atrophic gastritis with intestinal metaplasia (CAGIM) are associated with gastric carcinoma. We, therefore, analysed bile acids in the antral mucosa in controls (n = 10), in patients with CAG (n = 12) and CAGIM (n = 20). In both forms of chronic antral gastritis, total mucosal bile acid concentrations drop, caused mainly by lower primary bile acids. The proportions of secondary bile acids rise, in particular of toxic lithocholic acid. This is probably caused by bacterial activity in the stomach. Whether secondary bile acids, especially lithocholic acid, alone or in combination with other bacterial degradation products, influence gastric carcinogenesis remains to be elucidated in further studies.

Adult↗
PubMed1988

Thr28, Nle31 CCK-9--an useful CCK analogue in stimulation tests of pancreatic exocrine function.

In the present study we examined the effect of Thr28 Nle31-CCK 25-33 (CCK-9) on pancreatic exocrine function in man. In subjects without pancreatic disease CCK-9 together with i.v. secretin (0.5 CU/kg/h) elicited a maximal stimulation of amylase output at a dose of 10 pmol/kg/h while trypsin and chymotrypsin were stimulated maximally at a dose of 30 pmol/kg/h. Higher doses of 60 and 100 pmol/kg/h had no additional effects. Lipase secretion was stimulated by secretin alone with no additional effect of CCK-9. During all doses of CCK-9 no side effects were observed. In patients with chronic pancreatitis a dose of 30 pmol/kg/h was also sufficient to obtain maximal enzyme output. In conclusion this derivative of CCK can be considered as a potent and useful alternative to amphibian caerulein in direct pancreatic function tests.

Alcoholism↗
PubMed1987

[First laser irradiation of a bile duct carcinoma under endoscopic control].

For the first time a hepatic-duct carcinoma was treated palliatively with percutaneous endoscopic Neodym-YAG laser irradiation. This enlarged the lumen of the bile duct encased by tumour. The method can be combined with prosthetic as well as radiotherapeutic procedures. The equipment consists of an ordinary choledochoscope and a laser apparatus. The choledochoscope merely needs minimal technical modification of the outer valve of its working channel. Biopsies under endoscopic control make it possible to obtain tissue samples adequate for histological examination before treatment is begun.

Adenocarcinoma↗
PubMed1987

A calmodulin antagonist inhibits histamine-stimulated acid production by isolated rat parietal cells.

The role of calmodulin in the regulation of histamine-stimulated parietal cell function was studied in isolated rat parietal cells using [14C]aminopyrine uptake as a quantitative index of acid production. In enriched (77-87%) intact parietal cells the calmodulin antagonist naphthalene sulfonamide W 7 dose-dependently inhibited the response to 10(-4) M histamine (IC50: 2 X 10(-6) M). The mechanism of this inhibition was examined further with two other stimuli of H+-production: forskolin which directly activates the parietal cell adenylate cyclase without interacting at the histamine H2-receptor and dbcAMP which mimics the biological action of cAMP without preceding activation of adenylate cyclase. W 7 effectively inhibited the responses to 10(-4) M forskolin (IC50: 6 X 10(-7) M), 10(-3) M dbcAMP (IC50: 10(-6) M) and to 10(-2) M K+ (IC50: 3 X 10(-6) M). The action of W 7 followed non-competitive kinetics since the antagonist reduced the entire range of the concentration-response curves without shifting them rightwards towards higher concentrations of the respective stimulants. The effect of W 7 was reversed by washing the cells. ATP-induced [14C]aminopyrine uptake into digitonin-permeabilized oligomycin-inhibited parietal cells reflects H+-production independent of oxidative phosphorylation and was also inhibited by W 7 (IC50: 10(-5) M). Inhibition of K+-stimulated H+/K+-ATPase activity required even higher W 7-concentrations (IC50: 1.4 X 10(-4) M). Our data suggest that calmodulin might be involved in the intracellular mediation of the response to histamine. Between histamine-induced cAMP-generation and the H+-secreting tubulovesicular system W 7 seems to inhibit an intracellular step that finally activates the H+/K+-ATPase. Yet, direct inhibition of the ATPase requires W 7 concentrations of questionable specificity and is unlikely to be the mechanism behind the action of W 7 on the parietal cell response to histamine.

Adenosine Triphosphatases↗
PubMed1987

Palliation of obstructive oesophageal and cardial carcinomas with laser and endoluminal iridium radiation.

The combination of laser with endoluminal 192-iridium radiation for the palliation of malignancies of the oesophagus and the cardia has been introduced to overcome the short-lived effect of laser treatment alone. Concluding from early experience, this method seems to prolong the effect of laser treatment alone, with a low risk of complications. However the initial optimistic results, claiming a permanent relief of dysphagia in 80% of the patients, cannot be reproduced under prospective conditions. The combination of laser and 192-iridium radiation with other palliative methods, such as external radiation and/or chemotherapy is feasible and remains to be studied in a comparative way.

Brachytherapy↗
PubMed1987

Electronic endoscopy--the latest technology.

At present, video endoscopic systems (VE) are available from four companies. We have had an opportunity to test these instruments in clinical practice. In principle, all the VE's are similar in that they employ charge coupling devices (CCD-chips) as image sensors, but they differ significantly in CCD chip technology and in the color acquisition technique. The basic aspects of CCD chip and transmission technology of relevance to the endoscopist are discussed. The mechanical properties of the endoscopes are listed. Finally, we provide an outlook on the determinants of the optical performance of VE's. The optical performance of a VE can be characterized by its resolution and color performance.

Colonoscopes↗
PubMed1987

Video-endoscopes in comparison with fiberscopes: quantitative measurement of optical resolution.

The subject of this study was the optical performance of video-endoscopic systems (VE) in terms of maximal resolving power and resolvable picture elements. Olympus, Toshiba/Machida, Fujinon, and Welch Allyn video gastroscopes were tested. A GIF Q 10 fiberscope from Olympus was also included for comparison. The resolution measurements were made at various distances using two independent methods--electronic analysis of the TV signal, and visual evaluation of the resolution, of a standardized test target. The results obtained with the two methods were in perfect agreement. The resolution of fine details clearly depends on the distance between the distal end and the target because of decreasing image scale. Depending on the individual optical design, the various VE's show maxima at different distances. At shorter distances, the image is degraded by defocusing. An optimal distance which is as small as possible is desired for clinical routine. Apart from the fiberscope this requirement is best met by the Fuji system. The greatest resolution is obtained with the Toshiba system but at the cost of the viewing angle which is the smallest of all the systems. Fuji combines relatively high resolution with a large viewing angle. Because of the widely varying viewing angle a comparison based solely on resolution cannot represent the true imaging capability of the system. We therefore eliminated purely optical parameters and calculated the number of resolvable picture elements per line. We regard this number to be a fair characterization of both TV and fiber systems.

Fiber Optic Technology↗
PubMed1987

Fractional cleansing of the large bowel with "Golytely" for colonoscopic preparation: a controlled trial.

"Golytely", a lavage solution for colonoscopic preparation, has been in clinical use since 1980. Patients usually drink all the fluid (4-61 "Golytely") the morning before colonoscopy. However, clinical observation shows that many, especially elderly, patients have difficulty tolerating these large volumes. We therefore compared two methods of drinking "Golytely" in 36 patients: One group of 18 patients underwent a two-stage lavage preparation (in the evening and the following morning before the examination), the other group drank all the fluid in the early morning before colonoscopy. Patients tolerated the two-stage method significantly better-in terms of nausea (p less than 0.05) and their willingness to repeat the procedure (p less than 0.001). In both groups the bowel was equally clean and the amount of fluid required for preparation did not differ. We conclude that this new method of drinking "Golytely" is far more convenient for the patient and does not reduce the effectiveness of bowel preparation.

Adult↗
PubMed1987

Color performance of video endoscopes: quantitative measurement of color reproduction.

We have conducted a study aimed at testing the color performance of video endoscopes in quantitative terms for the first time. The video endoscopes investigated were from Fuji, Olympus, Toshiba/Machida, and Welch-Allyn. The tests were carried out with an opto-electronic color analyser using standardized color charts and a neutral grey chart. Hue and chroma of the reproduced colors were measured. The Olympus video endoscope reproduces the hue very well, showing only slight color desaturation. The Fuji video endoscope had a yellowish tint, whereas the picture obtained with the WA video endoscope produced an inhomogeneous picture with a pronounced red/purplish cast at the top of the screen and almost neutral reproduction at the lower half. The Toshiba video endoscope was the only one with a color chip, and reproduced hue fairly well, but its colors were weakly saturated.

Color↗