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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

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↗
PubMed1987

Laser and endoluminal 192-iridium radiation.

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

Brachytherapy↗
PubMed1987

Endoprosthesis and local irradiation in the treatment of biliary malignancies.

Endoscopic biliary drainage by means of a bilio-nasal tube or stent (bilioduodenal endoprosthesis) provides an intermediate or long-term "bridge" for the interrupted bile flow. Insertion procedures are successful in 80-90% of the cases. Percutaneous transhepatic drainage serves as an alternative or complementary procedure to the endoscopic approach. Virtually every patient can be treated in this way when surgery is contraindicated or impossible. Endoscopic stenting is equally effective in relieving jaundice, but has a lower mortality rate and is associated with a shorter hospital stay than biliary surgery. Patients with tumorous obstruction of the liver hilum live significantly less long than those with cancerous occlusion of the hepatocholedochal duct. In the case of bile duct cancer, non-surgical drainage procedures can be combined with endoscopic or transhepatic irradiation employing 192-iridium for intraluminal irradiation; further studies are, however, needed. Endoscopy of the biliary tract (cholangioscopy) is available via the papilla of Vater and through the liver, and may in the future expand our diagnostic and therapeutic possibilities for the treatment of malignant biliary disorders.

Bile Duct Neoplasms↗
PubMed1987

The effects of 75 mg HOE 760, a novel H2-receptor antagonist, on daytime peptone-stimulated and nocturnal gastric acid output in healthy volunteers.

The effects of HOE 760, a highly specific H2-receptor antagonist, on daytime peptone-stimulated and nocturnal gastric acid output were studied (randomized, double-blind crossover) in 10 healthy men. Acid output was monitored at lunch (1200 h to 1400 h) and dinnertime (1800 h to 2000 h) by continuous automatic intragastric titration; from midnight to 0600 h, output was measured by titration of manually aspirated gastric contents. After a 75-mg oral dose (capsule containing HOE 760 granules) at 0800 h peptone-stimulated acid output decreased for at least 12 h. Compared with placebo, significant reductions (p less than 0.05) of 86% and 32% were observed 4-6 h and 10-12 h after drug administration. After another dose of 75 mg at 2100 h nocturnal acid output was significantly reduced (p less than 0.05) by 88%; gastric pH was increased by about 2 units throughout the night. HOE 760 was well tolerated. No adverse reactions occurred; no clinically relevant changes were noted in haematologic, biochemical, urinary, or electrocardiographic variables.

Adult↗
PubMed1987

Computer-aided formulation of physician's reports and storage of ERCP data.

In the 2nd Medical Dept. of the Technical University of Munich, endoscopic retrograde cholangiopancreatography (ERCP) reports are written with the aid of a computer. The doctor doing the examination enters the ERCP data into screen masks. The data are stored at once in a data bank. This data bank system permits immediate error checks of the variables entered, singly and in combination. Errors can be corrected in a loop. Generating of ERCP reports is controlled by a text file, which contains both control statements and standard phrases. A special program for the document generating was developed by the authors and has been used for 15 years in various applications.

Cholangiopancreatography, Endoscopic Retrograde↗