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Biomedical subjects

M Classen

Publications and source records attributed to M Classen.

At least 73 records · Page 4Linked to original sources
PubMed1991

Phenotypic and functional characterization of human TCR gamma delta+ intestinal intraepithelial lymphocytes.

Intestinal intraepithelial lymphocytes (IEL) appear to represent a peculiar set of immune cells compartmentalized at the interface between the organism and the external environment. In previous studies we observed that within human IEL TCR-tau/delta T cells represent a major fraction that predominantly express the CD8 molecule and preferentially uses the V-delta-1 gene segment. Thus these data suggested a preferential accumulation/homing of CD8+ V-delta-1+ IEL within the human intestinal epithelium. However, to date the functional role of these cells with regard to immune regulation at this most critical immunological site is poorly understood. In this study, the cytotoxic potential and proliferative capacity of human IEL in response to mitogenic stimuli has been characterized with respect to IEL T cell receptor type and TCR-tau/delta variable gene segment usage as determined by flowmetry. The frequency of TCR-1+ IEL expressing both CD56 and CD16 which are considered to be NK-cell markers was found to be much higher (38.9 +/- 12.4%) than within intestinal lamina propria lymphocytes (LPL) (9.1 +/- 4.8%) or peripheral blood lymphocytes (PBL) (6.4 +/- 3.3%). In contrast, the fractions of CD16-CD56+ cells within IEL, LPL and PBL were comparable. Surprisingly, IEL mediated NK-cell activity (K562 lysis) was virtually absent whereas within PBL it was within the normal range. Furthermore, in cytotoxicity assays employing 51Cr-labeled OKT3 hybridoma cells and P815 cells as targets, the cytotoxic potential of IEL was much lower than that of PBL.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Interaction of trimebutine and Jo-1196 (fedotozine) with opioid receptors in the canine ileum.

Receptor binding of the opioid receptor antagonist, [3H]diprenorphine, which has a similar affinity to the various opioid receptor subtypes, was characterized in subcellular fractions derived from either longitudinal or circular smooth muscle of the canine small intestine with their plexuses (myenteric plexus and deep muscular plexus, respectively) attached. The distribution of opioid binding activity showed a good correlation in the different fractions with the binding of the neuronal marker [3H]saxitoxin but no correlation to the smooth muscle plasma membrane marker 5'-nucleotidase. The saturation data (Kd = 0.12 +/- 0.04 nM and maximum binding = 400 +/- 20 fmol/mg) and the data from kinetic experiments (Kd = 0.08 nmol) in the myenteric plexus were in good agreement with results obtained previously from the circular muscle/deep muscular plexus preparation. Competition experiments using selective drugs for mu [morphiceptin-analog (N-MePhe3-D-Pro4)-morphiceptin] ), delta (D-Pen2,5-enkephalin) and kappa (dynorphin 1-13, U50488-H) ligands showed the existence of all three receptor subtypes. The existence of kappa receptors was confirmed in saturation experiments using [3H] ethylketocycloazocine as labeled ligand. Two putative opioid agonists, with effects on gastrointestinal motility, trimebutine and JO-1196 (fedotozin), were also examined. Trimebutine (Ki = 0.18 microM), Des-Met-trimebutine (Ki = 0.72 microM) and Jo-1196 (Ki = 0.19 microM) displaced specific opiate binding. The relative affinity for the opioid receptor subtypes was mu = 0.44, delta = 0.30 and kappa = 0.26 for trimebutine and mu = 0.25, delta = 0.22 and kappa = 0.52 for Jo-1196. Thus, Jo-1196 had some selectivity for kappa receptors compared to trimebutine. We conclude that there are similar types of opioid receptors in the myenteric plexus and the deep muscular plexus and that specificity of function of opioid nerves must depend on differential location of receptor types on particular neurons. The action of trimebutine and related drugs could vary depending upon their interactions with various gut opioid receptors having different physiological roles.

5'-Nucleotidase↗
PubMed1991

[Endoscopic ultrasound in small pancreatic tumors].

32 of 89 pancreatic tumors examined by endoscopic ultrasonography (EUS) from January 1986 to February 1990 had a diameter of 3 cm or less. The final diagnosis of a malignant (n = 28) or benign (n = 4) pancreatic neoplasma was achieved by operation, puncture or autopsy. The accuracy of EUS (100%) was higher than for ultrasound (61%), computed tomography (64%) or endoscopic-retrograde cholangiopancreatography (84%). The echopattern of the small pancreatic carcinomas showed, compared to larger neoplasms, less often regressive changes (21 vs. 77%) and a well demarcated or smooth tumor margin (25 vs. 2%). However, it is not possible to differentiate reliably a small malignant from a benign pancreatic tumor by the echofeatures alone. Since most pancreatic tumors are large at the time of clinical presentation, they can be visualized by conventional imaging methods in most cases. EUS adds clinically important information to the diagnosis of pancreatic carcinoma especially in small tumors.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1990

[Sonographic percutaneous drainage of liver abscesses].

13 patients with pyogenic liver abscess and five patients with amoebic abscess underwent percutaneous drainage of the abscesses using the Seldinger (n = 8) or trocar technique (n = 11). The results showed that the trocar method was easier and faster to perform and well tolerated by the patients. No complications were observed despite of one case of transient peritonitis caused by a dislocated catheter. One patient with pyogenic liver abscess died of septic shock. All other patients were successfully treated, using local drainage and systemic antibiotic therapy.

Aged↗
PubMed1990

Vagally induced release of gastrin, somatostatin and bombesin-like immunoreactivity from perfused rat stomach. Effect of stimulation frequency and cholinergic mechanisms.

The isolated stomach of rats was vascularly perfused to measure the secretion of gastrin, somatostatin (SLI) and bombesin-like immunoreactivity (BLI). The gastric lumen was perfused with saline pH 7 or pH 2, and electrical vagal stimulation was performed with 1 ms, 10 V and 2, 5 or 10 Hz, respectively. Atropine was added in concentrations of 10(-9) or 10(-7) M to evaluate the role of cholinergic mechanisms. In control experiments, vagal stimulation during luminal pH 2 elicited a significant increase of BLI secretion only at 10 Hz but not at 2 and 5 Hz. Somatostatin release was inhibited independent of the stimulation frequency employed. Gastrin secretion at 2 Hz was twice the secretion rates observed at 5 and 10 Hz, respectively. At luminal pH 7 BLI rose significantly at 5 and 10 Hz. SLI secretion was decreased by all frequencies. Gastrin secretion at 2 and 5 Hz was twice as high as during stimulation with 10 Hz. Atropine at doses of 10(-9), 10(-8), 10(-7) and 10(-6) M had no effect on basal secretion of BLI, SLI and gastrin. At luminal pH 2, atropine increased dose-dependently the BLI response at 2 and 5 but not at 10 Hz. The decrease of SLI during 2 and 5 Hz but not 10 Hz was abolished by atropine 10(-9) M. SLI was reversed to stimulation during atropine 10(-7) M at all frequencies. The rise of gastrin at 2 Hz was reduced by 50%. At luminal pH 7, atropine had comparable effects with a few differences: the BLI response at 10 Hz was augmented and the gastrin response to 2 and 5 Hz was reduced. In conclusion the present data demonstrate a frequency and pH-dependent stimulation of BLI and gastrin release. The stimulation of BLI is predominantly due to atropine-insensitive mechanisms while muscarinic cholinergic mechanisms exert an inhibitory effect on BLI release during lower stimulation frequencies (2 and 5 Hz) independent of the intragastric pH and also during higher frequencies at neutral pH. Both, atropine sensitive and insensitive mechanisms are activated frequency dependent. The atropine-sensitive cholinergic mechanisms but not the noncholinergic mechanisms involved in regulation of G-cell function are pH and frequency dependent. Somatostatin is regulated largely independent of stimulation frequency and pH by at least two pathways involving cholinergic mechanisms of different sensitivity to atropine. These data suggest a highly differentiated regulation of BLI, gastrin and SLI secretion and the interaction between these systems awaits further elucidation.

Animals↗
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↗