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Biomedical subjects

M Classen

Publications and source records attributed to M Classen.

At least 199 records · Page 11Linked to original sources
PubMed1990

[Endosonographic diagnosis of pancreatic tumors].

140 patients (72 men, 68 women; mean age 57 [26-83] years) with suspected pancreatic tumours were investigated by endoscopic ultrasound (EUS) and also by conventional ultrasound, computed tomography (CT) and endoscopic retrograde cholangiopancreatography (ERCP). The EUS scans were performed with an echo-endoscope in the descending part of the duodenum (for the head of the pancreas) or in the stomach (for the body and tail). The definitive diagnosis or exclusion of a pancreatic tumour (malignant n = 85, benign n = 4, inflammatory n = 23, no tumour n = 28) was made at operation (n = 63), by needle biopsy (n = 35), at necropsy (n = 4) or by clinical follow up (n = 38, mean 10.5 months). The sensitivity and specificity of endoscopic ultrasound (99% and 100%) were superior to the results given by conventional ultrasound scans (71% and 39%), CT (82% and 46%) and ERCP (89% and 64%). This was also true of small tumours of 3 cm or less (EUS 100%, conventional ultrasound 57%, CT 68% and ERCP 89%). However, the differential diagnosis between malignant and inflammatory masses in the pancreas was not feasible by endoscopic ultrasound, either prospectively (detection rate 69%) or by comparative analyses of echo structure. Endoscopic ultrasound appears to be a valuable aid to the diagnosis or exclusion of pancreatic tumours. When conventional ultrasound and CT give negative or doubtful results it can be used in conjunction with or instead of ERCP to confirm the diagnosis.

Adult↗
PubMed1990

[Endoscopic and percutaneous implantation of self-expanding endoprostheses in biliary stenosis].

Self-expanding metal stents were implanted in 30 patients (14 men and 16 women, mean age 67 [40-86] years) with malignant (n = 27) or benign (n = 3) obstruction of the biliary tract (hepatic duct bifurcation: n = 14; choledochal duct: n = 16). The stents were introduced and left in place endoscopically in 13, percutaneously and transhepatically via a 7 or 9 F catheter in 17 patients. The stents, which expand to a diameter of 7-10 mm, in all cases achieved complete drainage, as confirmed by cholangiography. Jaundice completely disappeared in 28 of 30 patients. No complications were noted during a 30-day period of observation. After a median follow-up period of 90 days, 17 patients have been without jaundice for a median period of 141 (30-330) days. A recurrence of jaundice was noted in three patients (restenosis proximal to the stent in 2, incrustation with bile in one). Ten patients died, without any signs pointing to stent occlusion. These data indicate that the probability of stent patency in malignant stenoses of 200 days after implantation is 84%, so that stents in most cases provide a safe and effective means of drainage. Because they have a relatively large lumen with small surface area infection, occlusion and migration apparently occur less often than with conventional synthetic prostheses.

Adult↗
PubMed1990

Bombesin-like peptides stimulate gastrin release from isolated rat G-cells.

Bombesin-like peptides as well as receptor-independent activators were tested for their effect on gastrin release from acutely dispersed rat gastric G-cells. The amphibian peptide bombesin as well as its mammalian analogues neuromedin B and neuromedin C stimulated gastrin release. Maximal responses were achieved with 10(-9) M bombesin (191.0 +/- 16.8% of basal release), 10(-8) M neuromedin C(205.9 +/- 17.6%) and 10(-7) M neuromedin B (162.2 +/- 10.4%), respectively. The phorbol ester 12-O-tetradecanoyl-phorbol 13-acetate (TPA) and the synthetic diacylglycerol analogue 1-oleoyl-2-acetyl-sn-glycerol (OAG) are receptor-independent activators of the protein kinase C. Both TPA (10(-6) M) and OAG (10(-5) M) stimulated gastrin release to 214.0 +/- 29.3% and 198.2 +/- 20.8% of basal, respectively. Calcium ionophore A23187 (10(-5) M) was the most effective stimulant tested (364.7 +/- 39.6%). Its effect was reversed by the calmodulin antagonist W 7 (10(-6)-10(-5) M). Finally, forskolin (10(-5) M), a direct activator of cAMP-formation, as well as the cAMP-analogue dbcAMP (10(-3) M) induced gastrin release. IN conclusion, neuromedin B is less potent and less effective than neuromedin C and bombesin in stimulating rat gastric G-cells. In addition, gastrin release is activated by calcium- and phospholipid-dependent as well as by cAMP-induced cellular signal transduction mechanisms.

Amino Acid Sequence↗
PubMed1990

Toxic shock-like syndrome due to severe hemolytic group A streptococcal infection.

A 33-year-old woman suffering from anal erosions developed severe illness with fever, diarrhea, ischalgia, hypotension, acute abdominal pain, dyspnea, renal and hepatic impairment, myalgia, desquamation of the skin, leukocytosis, anemia, hypocalcemia, decreased serum albumin, and cholesterol levels. Exploratory laparotomy did not reveal pathologic findings. Hemolytic group A streptococci were grown from peritoneal swabs and pleural exudate in bacteriologic cultures. The patient slowly recovered after intense penicillin and tobramycin therapy.

Adult↗
PubMed1990

Effect of thyrotropin-releasing hormone on immune functions of peripheral blood mononuclear cells.

The tripeptide thyrotropin-releasing hormone (TRH) works as a hypothalamic hormone, but is found also outside the brain in intrinsic nerve fibers of the gastrointestinal tract. There is evidence that TRH modulates the activity of immunocompetent cells, although there are only very few data on TRH-mediated immune effector functions. Since we could recently show that TRH inhibits monocyte activities we were also interested in other possible TRH modulated immune functions. Peripheral blood mononuclear cells (PBMC) from ten healthy subjects were cultured for 7 days and pulsed with 0.125 and 0.250 microgram/ml Pokeweed mitogen (PWM). 10(-12) to 10(-6) M TRH was added simultaneously with PWM. Lymphocyte proliferation [(3H]thymidine incorporation), interferon-gamma (IFN-gamma) activity (RIA) and immunoglobulin activities (IgG, IgM, IgA; ELISA) were determined in the supernatants. We could demonstrate a TRH-dependent decrease in PWM-pulsed IgG activity with significant (alpha = 0.05) values at 10(-8) and 10(-10) M (-29 +/- 6%/-16 +/- 3% for PWM 0.125 microgram/ml and -17 +/- 9%/-11 +/- 9% for PWM 0.250 microgram/ml). This inhibitory effect could be abolished by an anti-TRH antiserum. There was no TRH effect on IgM and IgA activities, IFN-gamma activity and lymphocyte proliferation compared with the PWM stimulated values alone. The described TRH effect on the polyclonal IgG response by PBMC gives further evidence for a functional link between the immune system and the endocrine system, although its underlying mechanism is not yet clear.

Enzyme-Linked Immunosorbent Assay↗
PubMed1990

[Colon endosonography. Initial experiences in clinical use].

For the first time we report about a new diagnostic technique, the endoluminal ultrasound of the colon. It enables us to examine the whole colon by an ultrasound endoscope. The ultrasound frequency of the instrument (XCF-UM2, Olympus Optical/Aloka, Japan) is 7.5 MHz, the roundview is approximately 320 degrees. The mean advantage is the combination of endoscopic inspection including biopsy and endoluminal ultrasound. First clinical experience was gained at a total of 27 examinations. It was possible to demonstrate the normal colonic wall (n = 10) in the entire large bowel, neighbouring organs could be visualized clearly and reproducibly in most cases. Pathologic findings (four carcinomas, eight polyps, five anastomoses) were correctly diagnosed by endosonography with a sensitivity of 100% and a specificity of 96%. In two cases the histopathologic work-up of the resected specimens confirmed the ultrasonographic diagnosis of malignancy, while the endoscopic biopsy indicated benign wall lesions. This suggests that endosonography may be superior to histological diagnosis by biopsy in some cases.

Adult↗
PubMed1990

[Electromagnetic shockwave lithotripsy of gallstones. Preliminary clinical experiences].

75 applications of extracorporeal electromagnetically produced shock-waves were performed on 40 patients with symptomatic gallbladder stones (27 women and 13 men; mean age 43.5 [25-69] years). The patients had up to three stones each, with a maximal diameter of 35 mm. Computed tomography revealed partial calcification of the stones in nine patients. Stone fragmentation succeeded in all patients. Two weeks after lithotripsy two patients were free of stone. Maximal fragment diameter, as measured by ultrasound, was less than 6 mm in 19 patients, 6-10 mm in 14, and 11-15 mm in five. At reexamination of 24 patients three months later, three additional patients were free of stone by ultrasound. No significant side effects were noted during the first 30 days after the procedure. But during further observation mild pancreatitis developed in two, while in one choledochal concrements caused obstructive jaundice which necessitated endoscopic papillotomy. These results demonstrate the effectiveness of this method of fragmenting gall-bladder stones.

Adult↗
PubMed1990

Effect of substance P on immunoglobulin and interferon-gamma secretion by cultured human duodenal mucosa.

Recently, we have demonstrated a substance P (SP)-dependent modulation of in vitro IgM and interferon-gamma (IFN-gamma) secretion by human peripheral blood mononuclear cells, as well as lymphokine activities in supernatants of cultured duodenal mucosa. Therefore we investigated other local immunoregulatory effects of SP. Duodenal biopsies of 7 healthy subjects were cultured with Pokeweed mitogen (PWM, 1 microgram/ml) for 4 days at 37 degrees C in 1 ml medium each. SP was added in concentrations ranging from 10(-12)M to 10(-6)M on day 1. Fresh media with fresh PWM were added every day. IgG, IgM, IgA (ELISA) and IFN-gamma (RIA) were determined in the culture supernatants. Values were referred to 5 mg biopsy weight and expressed as % change in basal PWM pulsed secretion, or as units/ml. 10(-6) M and 10(-12) M SP increased secretion of all immunoglobulin isotypes. Compared to controls, 10(-6) M and 10(-12) M SP led to an increase in IgM secretion of up to 73 +/- 23% and 41 +/- 32% and to an increase in IgA secretion up to 96 +/- 35% and 25 +/- 33%, respectively (alpha = 0.02 for both isotypes at 10(-6) M). 10(-12) M to 10(-6) M SP led to a significant dose-dependent increase in IFN-gamma secretion from 7.08 +/- 1.65 up to 21.8 +/- 12.6 units/ml/5 mg. The maximum effect could be seen on culture days 3 and 4. We were able to demonstrate for the first time that SP stimulates PWM pulsed immunoglobulin and IFN-gamma secretion by human duodenal immunocompetent cells. These results support the hypothesis of local neuropeptidergic-immune interactions.

Adult↗
PubMed1990

Complications of diagnostic gastrointestinal endoscopy.

Undesired side effects and complications of gastrointestinal endoscopy and premedication are rare events. However, this is true only of endoscopic units with experienced investigators, modern equipment and monitoring. The complication rate of upper gastrointestinal endoscopy is about 0.1% with cardiopulmonary events predominating. The typical complication of colonoscopy is perforation, seen in 0.2%. The relevant ERCP specific complication is acute pancreatitis in about 1%, followed by acute cholangitis. The most serious complications of laparoscopy are hemorrhage from the liver biopsy site, bleeding from abdominal wall varices, and perforation of the colon. The cardiopulmonary mortality is low for upper gastrointestinal endoscopy as well as for colonoscopy (1 death/20,000 procedures). Premedication, chronic obstructive pulmonary disease, coronary heart disease, valvular heart disease and, last but not least, advanced age, must be considered risk factors for the development of complications of gastrointestinal endoscopy. Balanced indication, particularly in the elderly patient, should be the consequence. If possible, endoscopy should be performed without sedatives. If premedication is necessary, it should be used sparingly. Not only patients at high risk for the development of cardiopulmonary complications, but all patients undergoing endoscopy must be carefully monitored after premedication, during and after endoscopy. The non-invasive procedure of pulse-oximetry is appropriate for continuous monitoring of arterial oxygen saturation in patients with cardiopulmonary diseases, irrespective of their premedication status. Antibiotic prophylaxis is recommended in patients with valvular heart disease or prosthetic valves. Standardized cleaning and disinfection of the instruments is of great importance to avoid hepatitis B or HIV transfer.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1990

A new ultrasonic probe for endosonographic imaging of the upper GI-tract. Preliminary observations.

A new ultrasonic probe (7.5 MHz, diameter 3.7 mm) was used in vitro in 3 gastric resection specimens and in vivo in 12 patients in an attempt to visualize normal and pathological wall structure of the esophagus, stomach and duodenum via the working channel of a gastroscope, and of the biliary tract via the percutaneous approach. In 5 of these patients conventional endosonography was performed. The probe visualizes the normal layer structure and pathological lesions of the upper GI-tract wall, since it can be accurately positioned at the structure of interest under visual control; water is instilled into the hollow organs to improve transmission of the ultrasound beam. Intra- and transmural changes such as blood vessels in the wall of the esophagus and stomach in portal hypertension, or gastric and esophageal tumors were demonstrated. The important advantage of the probe is that it can be used in stenosed or narrowed hollow organs, where conventional endosonography fails. However, the depth of penetration of the ultrasonic beam (10-15 mm) and circumferential imaging of the gastric wall are still inferior to those of conventional endoscopic ultrasound. As the focus distance of the ultrasound probe to the biliary ducts is too small, visualization of the biliary system is incomplete. Technical improvements could make this new probe an irreplacable diagnostic tool in the future.

Diagnostic Imaging↗
PubMed1990

A 19-year-old female with blue rubber bleb nevus syndrome. Endoscopic laser photocoagulation and surgical resection of gastrointestinal angiomata.

A case of a blue rubber bleb nevus syndrome in a 19-year-old female patient with multiple cutaneous and gastrointestinal hemangiomata is described. Recurrent GI bleeding resulted in severe chronic anemia, which was successfully treated by endoscopic laser photocoagulation and surgical resection. Both forms of therapy had to be repeated 4 years later, the patient having been well in the meantime. This combined endoscopic and surgical approach might also improve the survival of patients with severe GI hemorrhage due to blue rubber bleb nevus syndrome.

Adult↗
PubMed1990

Effect of N-butylscopolamine on sphincter of Oddi motility in patients during routine ERCP--a manometric study.

N-butylscopolamine is a generally accepted drug for the suppression of gut motility. Although it is used during routine ERCP, only few systematic studies have been carried out in patients to investigate its action on sphincter of Oddi motility. In the present study the effect of N-butylscopolamine on the motility of the sphincter of Oddi region has been evaluated in 17 patients undergoing routine diagnostic ERCP. The pressure parameters of these patients were compared with "normal values" obtained in 23 volunteers. A dose of 40 mg of N-butylscopolamine bromide (Buscopan) i.v. significantly reduced the contraction frequency of the sphincter of Oddi from 5.4 +/- 1.2/min to 1.0 +/- 1.4/min (p less than 0.001), the contraction amplitude from 106.3 +/- 27.8 mmHg to 55.2 +/- 23.5 (p less than 0.01) mmHg, and the basal sphincter of Oddi pressure from 13.9 +/- 3.0 mmHg to 11.0 +/- 3.5 mmHg (p less than 0.05), but had no effect on the pressure gradient between the common bile duct and the duodenum. These results clearly demonstrate that N-butylscopolamine inhibits contractions of the sphincter of Oddi, and may thus facilitate the intubation of the papilla.

Adult↗
PubMed1990

Perspectives in "electronic endoscopy". Past, present and future of fibers and CCDs in medical endoscopes.

Electronic endoscopy has undergone considerable evolution in recent years. Early instruments had poorer resolution than fiberscopes, and distorted colors significantly. The second generation of electronic endoscopes has been considerably improved, and electronic endoscopy is expected to play a major role in endoscopy in the next decade, with its enhanced teaching abilities, permanent image storage, reproduction and retrieval. An important new development has been the development of a high-resolution colonoscope & gastroscope. Electronic endoscopes are now able to produce better resolution than fiberscopes, and the future should bring further improvements in resolution with electronic instruments. A number of problems still remain to be solved with electronic endoscopy. Irregular reflection from secretions, food and blood at short focus (less than 1 cm) results in a loss of resolution, which makes electronic endoscopy particularly difficult when bleeding is brisk. Electronic endoscopes synthesize color from a strobed signal of red, blue and green in a processor. Color is dependent on brightness, and at close focus, excessive brightness in the center of the field results in erratic color reproduction. Images acquired at electronic endoscopy may be digitized for storage and processing in a computer--which, however, is not a straightforward task at the present time. Image processing in electronic endoscopy is still in its early stages, but we anticipate that new developments in early diagnosis, classification and measurement of lesions will take place. Digitized images can also be transmitted via telephone lines, and it will soon be possible to instantaneously send images across the world.

Color↗
PubMed1990

Evaluation of inter- and intramolecular primary structure homologies of interferons by a Monte Carlo method.

Using Sellers TT algorithm, primary structure repeats have been described for interferon (IFN)-alpha, -beta 1, and gamma. To reevaluate these results and to extend them to IFN-beta 2 (interleukin-6), a modified algorithm was developed that uses a metric to define the "best" partial homology of two peptide sequences and to compare it to those detected in random permutations of the peptide. Using this approach, the known structural homologies of IFN-alpha with IFN-beta 1 and of human (Hu) IFN-gamma with murine (Mu) IFN-gamma were identified correctly. However, the primary structure repeats in the amino acid sequences of IFN-alpha, -beta 1, and -gamma turned out to be no better than those detectable in random permutations of these sequences. These results were confirmed using a different, nonlinear metric. A previously used approach to demonstrate significance was shown to produce false-positive results. No significant primary structure homologies were detected among IFN-beta 1, -beta 2, and -gamma. In contrast to the amino acid sequence analysis, the DNA sequence of HuIFN-beta 1 contained a significant repeat that had no significant counterpart in MuIFN-beta or in IFN-alpha. In conclusion, some previously reported results obtained with Sellers TT algorithm on amino acid sequences are easily explained as random similarities, and it is therefore strongly recommended that a method like ours should be used to control significance.

Algorithms↗