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Biomedical subjects

M Classen

Publications and source records attributed to M Classen.

At least 19 recordsLinked to original sources
PubMed1992

[Laparoscopic cholecystectomy: ERCP as standard preoperative diagnostic technique].

In a prospective study 250 patients with proven cholelithiasis and clinical, biochemical and ultrasound indications for laparoscopic cholecystectomy (LC) underwent endoscopic retrograde cholangiography (ERCP) and (if bile-duct stones had been shown) endoscopic papillotomy (EPT). The biliary system was demonstrated in 229 patients (91.6%). Biliary tract stones were confirmed in 18 of 68 patients in whom they had been suspected clinically. In addition, ERCP revealed small stones in the bile-duct in eight of 154 patients with normal biochemical results and unremarkable ultrasound imaging, and in seven patients bile-duct anomalies which required EPT or open cholecystectomy. However, in retrospect five of the patients with cystic duct anomalies could have been treated by LC. The complication rate of ERCP/EPT was 3.2%. It is concluded from these results that, in view of the cost and potential risk to the patient, ERCP before LC can be limited to patients suspected of having bile-duct stones, even though small stones may be missed.

Adolescent↗
PubMed1992

Ascending neural pathways in the rat ileum in vitro--effect of capsaicin and involvement of nitric oxide.

The aim of the present study was to develop and characterize an in vitro model of the rat ileum in which activation of the orally projecting neural excitatory pathway of the myenteric reflex is produced by electrical field stimulation anally to the recording site. The motility of a 10-cm segment of rat ileum was recorded using a perfused manometric assembly with side holes 2 and 4 cm orally to the stimulation site. Electrical field stimulation caused a contractile response in the oral but not in the aboral direction of the stimulation site. The contractile response, which was maximal using low stimulus frequencies (3 or 5 pulses per second (pps)) and decreased with higher frequencies (10 or 20 pps), was blocked by atropine (10(-6) M) at all frequencies tested after acute and after prolonged (greater than 30 min) treatment. The maximal contractile response at 3 pps was abolished by hexamethonium (10(-4) M), tetrodotoxin (5 x 10(-7) M) and by complete transection of the muscular wall between the stimulation and the recording site. Acute administration of capsaicin (8 x 10(-7) M) to the bath reduced the lag between the start of the electrical stimulation and the onset of the contractile response. Higher concentrations of capsaicin (10(-5) M) reduced the contractile response, but this was partly due to an unspecific effect of capsaicin. Blockade of nitric oxide (NO) synthesis by L-NG-nitro-arginine-methyl ester (L-NAME) (3 x 10(-4) M) augmented the contractile response to anal stimulation by 222.4% and reduced the lag period by 54.5%, whereas the stereoisomer D-NAME had no significant effect. The potentiating effects of L-NAME were reversed in the presence of L-arginine (3 x 10(-3) M) but not in the presence of the stereoisomer D-arginine (3 x 10(-3) M). This model can be used to study ascending neural pathways in the rat small intestine. The ascending excitatory response is abolished by atropine and hexamethonium and is modulated by capsicin-sensitive fibers. The ascending pathway is under tonic inhibition of metabolites of the L-arginine-NO pathway.

Analysis of Variance↗
PubMed1992

[The endosonographic staging of pancreatic carcinoma].

Endoscopic ultrasound (EUS), conventional ultrasound (US), computed tomography (CT) and angiography were compared in their assessment of local resectability in 35 consecutive patients (19 men, 16 women; mean age 49.8 [42-821] years) with non-metastatic carcinoma of the pancreas. The findings were made prospectively and independently of each other. EUS proved to be superior to transabdominal US and to CT in the diagnosis of tumour infiltration of the portal and splenic veins. For the portal vein the sensitivity was 93% by EUS, 14% by US and 36% by CT. Corresponding figures for the splenic vein were 92%, 39% and 69%. EUS was markedly superior to angiography in the diagnosis of portal vein involvement (sensitivity of 93% and 36%, respectively), but the two methods had similar sensitivity regarding splenic vein infiltration (92 and 100%). Tumour involvement of the coeliac trunk was diagnosed with higher sensitivity angiographically (86%) than by EUS (57%), CT (71%) or US (29%). Regarding T and N staging, EUS was superior to both US and CT. These data indicate that EUS is the most accurate method for local tumour staging of potentially resectable pancreatic carcinoma. It can replace angiography in the diagnosis of portal vein infiltration.

Adult↗
PubMed1992

[The chemical composition of gallstones and their suitability for litholysis and lithotripsy].

The chemical composition of gallstones removed at surgery from 107 patients (81 women, 26 men; mean age 59 [18-85] years) was examined. In 64 women (79%) and 21 men (81%) microchemical analysis demonstrated concrements with a more than 50% cholesterol content (500 mg/g). Using as definition of cholesterol stones a 75% cholesterol content, only 35 women (43%) and 10 men (39%) would be classified as cholesterol stone carriers. Grossly visible layer formation was present in 18 stones; in eight stones calcium content was higher in the outer layer than in the core. There was no demonstrable relationship between gallstone composition and age.

Adolescent↗
PubMed1992

Idiopathic portal hypertension in a renal transplant patient after long-term azathioprine therapy.

We report the case of a patient with renal insufficiency who was admitted for the evaluation of splenomegaly. He had received a kidney allograft 6 1/2 years ago. Treatment with azathioprine and prednisolone for immunosuppression had been discontinued 1 year before admission. The underlying cause of the splenomegaly appeared to be an idiopathic portal hypertension. Until now, this disease has been described in only 13 kidney transplant patients receiving long-term immunosuppressive therapy with azathioprine. For the first time we demonstrate that azathioprine can cause this chronic liver disease even if the drug has been withdrawn some time before. Therefore, the indication for azathioprine must be considered very carefully.

Angiography↗
PubMed1992

Aerobilia and hypomotility of the sphincter of Oddi in a patient with chronic intestinal pseudo-obstruction.

A 50-year-old woman with a typical history of chronic idiopathic intestinal pseudo-obstruction was admitted to hospital because of an acute episode of abdominal cramps, nausea, and vomiting. The diagnosis of chronic idiopathic intestinal pseudo-obstruction had been established in this patient who had malnutrition and extreme weight loss as a result of severe malabsorption syndrome. The abdominal roentgenogram showed a typical hypotonic intestine with an enlarged stomach and distended intestinal loops with the radiological signs of an ileus. In addition to former episodes, there was also a transient aerobilia. The patient had not undergone biliary surgery or endoscopic sphincterotomy. To investigate the cause of the findings, endoscopic retrograde cholangiopancreatography and endoscopic manometry of the sphincter of Oddi were performed. The endoscopy showed the stomach and duodenum with a wide and dilated lumen and no spontaneous motility. Endoscopic manometry of the biliary tract and the sphincter of Oddi showed several abnormalities compared with a group of normal volunteers or patients who were examined via biliary manometry for other reasons. There was a low basal pressure (3.5 mm Hg) in the sphincter of Oddi together with low-amplitude phasic contractions (25-30 mm Hg), but the contraction frequency was in the normal range. Further investigations of the motility of the gastrointestinal tract in this patient showed diffuse esophageal spasms and a markedly delayed gastric emptying. The findings of biliary manometry in this patient suggest involvement of the sphincter of Oddi and the biliary system in chronic idiopathic pseudo-obstruction.

Air↗
PubMed1992

Staging of pancreatic and ampullary carcinoma by endoscopic ultrasonography. Comparison with conventional sonography, computed tomography, and angiography.

In a prospective study, endoscopic ultrasonography was compared with transabdominal ultrasonography, computed tomography, and angiography in 60 consecutive patients with pancreatic (n = 46) and ampullary (n = 14) cancer considered to be candidates for surgery. The diagnostic value of these imaging procedures in determining local resectability was assessed. The diagnosis of ampullopancreatic malignancy was made by operation (n = 40) or puncture/biopsy (n = 20). In the 40 patients who underwent surgery, endoscopic ultrasonography was significantly superior to abdominal ultrasonography and computed tomography in determining tumor size and extent and lymph node metastases of pancreatic and ampullary cancer. Furthermore, involvement of the portal venous system as judged by histopathology or surgical exploration was correctly assessed by endoscopic ultrasonography in 95%, whereas angiography (85%), computed tomography (75%) and abdominal ultrasonography (55%) were less sensitive. Of 11 cases of portal venous infiltration found at surgery, endoscopic ultrasonography correctly predicted 10, abdominal ultrasonography only 1, computed tomography 4, and angiography 5 (P less than 0.05 for all three comparisons). Twenty patients did not undergo surgery for different reasons: of those, 9 patients were excluded from operation because of portal venous involvement as shown by angiography. Endoscopic ultrasonography detected portal venous invasion in all these cases. In contrast to the venous system, arterial encasement was less reliably detected by endoscopic ultrasonography. In conclusion, endoscopic ultrasonography is the most effective single imaging procedure for local tumor staging in pancreatic and ampullary cancer. Thus, endoscopic ultrasonography will improve the assessment of tumor resectability and further decrease the need for explorative laparotomy.

Adult↗
PubMed1992

Pertussis toxin reverses prostaglandin E2- and somatostatin-induced inhibition of rat parietal cell H(+)-production.

In enzymatically dispersed enriched rat parietal cells we studied the effect of pertussis toxin on prostaglandin E2 (PGE2)- or somatostatin-induced inhibition of H(+)-production. Parietal cells were incubated in parallel in the absence (control cells) and presence of pertussis toxin (250 ng/ml; 4 h). [14C]Aminopyrine accumulation by both pertussis toxin-treated and control cells was used as an indirect measure of H(+)-production after stimulation with either histamine, forskolin or dibutyryl adenosine 3',5'-cyclic monophosphate (dbcAMP) alone and in the presence of PGE2 (10(-9)-10(-7) M) or somatostatin (10(-9)-10(-6) M). PGE2 inhibited histamine- and forskolin-stimulated [14C]aminopyrine accumulation but failed to alter the response to dbcAMP. Somatostatin was less effective and less potent than PGE2 in inhibiting stimulation by histamine or forskolin and reduced the response to dbcAMP. Pertussis toxin completely reversed inhibition by both PGE2 and somatostatin on histamine- and forskolin-stimulated H(+)-production but failed to affect inhibition by somatostatin of the response to dbcAMP. After incubation of crude control cell membranes with [32P]NAD+, pertussis toxin catalysed the incorporation of [32P]adenosine diphosphate (ADP)-ribose into a membrane protein of molecular weight of 41,000, the known molecular weight of the inhibitory subunit of adenylate cyclase (Gi alpha). Pertussis toxin treatment of parietal cells prior to the preparation of crude membranes almost completely prevented subsequent pertussis toxin-catalysed [32P]ADP ribosylation of the 41,000 molecular weight protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate↗
PubMed1992

Laser lithotripsy of pancreatic and biliary stones via 3.4 mm and 3.7 mm miniscopes: first clinical results.

The pulsed dye laser is safe and effective in lithotripsy of biliary and pancreatic ductal stones, however delivery of the laser energy to the site of the calculi is technically difficult. A 3.4 mm miniscope inserted through a standard duodenoscope was used for transpapillary laser application under direct vision in one patient with an impacted pancreatic stone and in three patients with bile duct stones not amenable to treatment by routine endoscopy. Lithotripsy and ductal clearance was achieved in 3 of the 4 patients within a single treatment session. Percutaneous transhepatic laser lithotripsy via a 3.7 mm miniscope succeeded in the patient in whom the peroral approach had failed and in two further patients with bile duct stones not accessible by a retrograde approach. There were no major complications. The miniscopes provide an appropriate direct visual control for laser lithotripsy of pancreatobiliary calculi. This approach using miniscopes seems to be an effective, minimally invasive and time-saving alternative to conventional endoscopic laser lithotripsy.

Adult↗
PubMed1992

Optical resolution and color performance of electronic endoscopes.

We studied the optical and color performance of Olympus fiber- and electronic endoscopes, including the EVIS 100 and EVIS 200 series. The measurements showed that the optical resolution of new generation videoendoscopes equals or exceeds that of fiberendoscopes. The close-up focusing ability has been extended. The color performance of the new EVIS 200 gastroscope enables clear distinction of all mucosal hues.

Color↗
PubMed1992

Implantation of self-expanding esophageal metal stents for palliation of malignant dysphagia.

Eleven self-expanding metal stents were perorally implanted in ten patients with locally advanced malignant obstruction of the esophagus. After bougienage of the strictures, the stents were painlessly inserted and properly released by means of an 18 French gauge delivery catheter. In all cases, the endoprostheses expanded to a diameter of 14-20 mm and achieved immediate improvement of dysphagia. One perforation was seen after a single session of dilatation and subsequent stent insertion. No other early complication was observed. After a median follow-up of 74 days (Range, 33-252 days), one of eight patients is still alive and 7 died of non-procedural causes. The grade of dysphagia improved from a mean of 2.9 to a mean of 1.6 and 2.0, respectively, depending on the follow-up period (scale 0-4). Esophageal reobstruction occurred in four patients due to food impaction (two patients) or tumor ingrowth into the stent through the wire mesh (two patients). Recanalisation of the obstructed stent lumen was achieved by endoscopic irrigation (two patients), laser therapy only (one patient) or diathermia with subsequent insertion of a conventional plastic endoprosthesis into the metal stent (one patient). The initial results are promising. The delivery system, the wide-bore diameter, the macroporous configuration and the low mass of the self-expanding stents would seem to be associated with a less traumatic insertion procedure and a lower rate of stent migration as compared with conventional prostheses. Technical improvement may be required for prevention of tumor infiltration. Controlled trials are warranted to determine the future role of metallic stents for palliation of esophagocardial tumors.

Adult↗
PubMed1992

Endoscopic laser lithotripsy with an automatic stone recognition system for basket impaction in the common bile duct.

In a patient with a common bile duct stone 28 mm in diameter, the traction wires of two basket catheters fractured during endoscopic mechanical lithotripsy. Disintegration of the concrement and removal of the impacted baskets failed even after extracorporeal application of 8,000 shockwaves. Pulsed dye laser lithotripsy was carried out via a 250 microns fiber which was advanced to the stone through a 6 French ERCP guiding catheter. Lithotripsy could be safely performed under fluoroscopic control since the laser used provides an automatic cut-out system upon tissue contact. 3,600 of 11,800 applied pulses were emitted with the total power setting and complete disintegration of the calculus was achieved. The baskets and the fragments could be removed endoscopically in the same session. Laser lithotripsy with a stone recognition system would seem to improve the applicability and safety of intracorporeal lithotripsy even when performed without direct visual guidance.

Aged↗
PubMed1992

Evaluation of laparoscopic cholecystotomy in the treatment of gallbladder stones.

Laparoscopic cholecystotomy (LCT) was attempted in 34 patients with biliary type symptoms; 33 patients suffered from gallbladder stones and one patient from gallbladder polyps. In one patient the gallbladder was not accessible with the laparoscope due to extensive adhesions. In the other patients endoscopic removal of stones and polyps was possible in all cases. In the first five patients the gallbladder was drained with a Foley type catheter at the end of the procedure; in the other patients the incision of the gallbladder was closed primarily with clips and fibrin glue. At the beginning of the series two cases of complications were observed: balloon catheter deflation due to material defect and postoperative bleeding into the gallbladder; after conventional cholecystectomy the two patients made an uneventful recovery. LCT is a one-session procedure suitable for removal of symptomatic stones in well functioning gallbladders with no restrictions concerning the composition, number or size of the stones.

Adult↗
PubMed1992

Prospective evaluation of the use of endoscopic retrograde cholangiography prior to laparoscopic cholecystectomy.

Preoperative cholangiography and subsequent removal of bile duct stones may increase the efficacy of laparoscopic cholecystectomy and reduce the rate of conversion to open cholecystectomy. Since there is little data on the incidence of choledocholithiasis in this group of patients, we undertook a prospective study on the routine performance of ERC in 288 patients selected for laparoscopic cholecystectomy. ERC succeeded in 264 of the 288 patients (91.7%) and showed a normal bile duct system in 227 (86.0%). Atypical bile duct anatomy was seen in eight patients. Open cholecystectomy was performed in seven of them but was judged to be absolutely necessary in only two cases (one patient each with Caroli syndrome and Mirizzi syndrome). ERC also revealed bile duct stones in 29 of 264 patients (11.0%) which had not been suspected on the basis of clinical, laboratory and ultrasonographic findings in nine cases (3.4%). EPT succeeded in all of the 29 patients with choledocholithiasis but open cholecystectomy was subsequently performed in four patients due to incomplete bile duct clearance (n = 3) or temporary bleeding after EPT (n = 1). The rate of ERC/EPT-related morbidity was 2.8%. It is concluded from a risk-benefit analysis in these patients that ERC should be restricted to patients with suspected bile duct stones. Following this strategy, small ductal concrements and bile duct abnormalities will be missed in 6.4% of cases but the clinical relevance of these findings is still unclear. In patients with combined gallbladder and common bile duct stones, preoperative EPT plus subsequent laparoscopic cholecystectomy appears to be an effective and time-saving therapeutic regimen which should be compared with open cholecystectomy plus common bile duct exploration in future studies.

Bile Duct Diseases↗
PubMed1992

Healing and relapse of duodenal ulcer during ranitidine therapy in the elderly. The RUDER Study Group.

A total of 2,109 outpatients with active duodenal ulcer (DU) entered an open, prospective study in order to investigate factors influencing healing and relapse during 2 years of ranitidine therapy (300 mg daily for healing, 150 mg as maintenance treatment). In a retrospective analysis, we evaluated the influence of age. Symptoms related to DU in 1,899 evaluable cases in patients over 65 years of age (n = 185) were identical to those of DU patients younger than 65 years old (n = 1,714). Rapid healing within 2 weeks of ranitidine therapy was less frequent in the elderly (32.5%) than in younger patients (40.7%) though identical healing rates (94.1%) in each group were achieved by continuation of ranitidine therapy for 8 weeks. Cumulative recurrence rates during the 2 years of long-term therapy were lower (17.3%) in old age than in patients under 65 years of age (23.3%). Adverse events were rare in both age groups. We conclude that DU healing during ranitidine is delayed in old age. Additional differences in relapse rates in favor of the elderly suggest that DU disease has a different course in the elderly.

Adult↗
PubMed1992

Contribution of postprandial amino acid levels to stimulation of insulin, glucagon, and pancreatic polypeptide in humans.

The present study was designed to examine the contribution of the postprandial increase of plasma amino acids after ingestion of a protein-rich meal to the rise of the three pancreatic hormones insulin, glucagon, and pancreatic polypeptide (PP). A mixed amino acid solution was designed, which permitted a fairly close imitation of the arterial plasma pattern of the 21 amino acids that rise after ingestion of a 200-g porcine steak meal. In 10 healthy subjects the intravenous infusion of this mixed amino acid solution at a rate of 10 g/h elicited a rise of the 21 amino acids examined that correlated well with the postprandial increase (r = 0.89, p < 0.001). The maximal rise of plasma insulin (64 +/- 5 pmol/L) and glucagon (630 +/- 21 ng/L) was not significantly different from the postprandial increase of these two hormones (49 +/- 4 pmol/L and 780 +/- 28 ng/L, respectively). PP levels rose by 316 +/- 33 ng/L postprandially, which was clearly above the increase of 112 +/- 13 ng/L during intravenous amino acids (p < 0.01). In conclusion, the present data demonstrate that the postprandial rise of amino acid levels in arterialized venous plasma can account for most if not all of the postprandial increase of insulin and glucagon during the ingestion of a protein-rich meal. In contrast, only 35% of postprandial PP levels can be ascribed to the rise of plasma amino acids. In contrast to the effect of carbohydrate-rich meals, an enteric augmentation of insulin release seems to be of minor and possibly of no importance during ingestion of protein-rich meals.

Adult↗
PubMed1992

Comparison of plasma bismuth levels after oral dosing with basic bismuth carbonate or tripotassium dicitrato bismuthate.

In 20 healthy subjects plasma bismuth concentration was measured after single oral doses of basic bismuth carbonate or tripotassium dicitrato bismuthate. The drugs were administered in the fasted state or immediately after ingestion of a standard breakfast. After basic bismuth carbonate, plasma bismuth rose to concentrations between 0.7 and 2.6 micrograms/L in the fasted state, while after the meal the maximal level was only 1.3 micrograms/L. In contrast to these very low levels after basic bismuth carbonate, the administration of tripotassium dicitrato bismuthate was paralleled by an increase of plasma bismuth to concentrations between 15 and 232 micrograms/L with a mean peak value of 64 +/- 15.3 (S.E.M.) micrograms/L in the fasted state. Postprandial ingestion of tripotassium dicitrato bismuthate attenuated the peak concentrations to 10.9 +/- 6.3 micrograms/L. One subject, however, had a value of 120 micrograms/L. This study demonstrates that basic bismuth carbonate leads to very low plasma bismuth concentrations, which are far below the critical range that might eventually be associated with bismuth neurotoxicity. Therefore this compound can be considered potentially useful for bismuth therapy of gastrointestinal disorders.

Administration, Oral↗