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Biomedical subjects

M Thelen

Publications and source records attributed to M Thelen.

At least 307 records · Page 17Linked to original sources
PubMed1990

Electromagnetically generated extracorporeal shockwaves for fragmentation of extra-and intrahepatic bile duct stones: indications, success and problems during a 15 months clinical experience.

Electromagnetically generated extracorporeal shock waves (without waterbath) were applied after intravenous premedication with 10-15 mg diazepam and 100 mg tramadol in the treatment of 33 patients (aged 32 to 91 years) with multiple intrahepatic stones (n = 4) or huge common bile duct stones (n = 29, 18-30 mm in diameter), which could not be removed by conventional endoscopy. Stone disintegration was achieved in 70% of common bile duct stones and in all intrahepatic concrements after 800-7500 discharges, which were applied during one (n = 21), two (n = 6) or three sessions (n = 6). Apart from mild fleabite-like petechiae at the side of shock wave transmission no other side effects were observed for a total of 51 procedures. We believe electromagnetically generated shock waves are safe, easy to apply, and relatively effective in the therapy of common bile duct and intrahepatic stones.

Adult↗
PubMed1990

Detection of dissection of the aortic intima and media after angioplasty of coarctation of the aorta. An angiographic, computer tomographic, and echocardiographic comparative study.

Balloon coarctation angioplasty (BCA) was performed in eight patients (five male and three female) who were 14-49 years old (mean, 27.3 years) with isolated discrete unoperated coarctation of the aorta (n = 7) and postoperative recoarctation (n = 1). BCA was successful in seven of eight patients, resulting in a decrease in the gradient (64 +/- 19 to 16 +/- 13 mm Hg, p less than 0.01), an increase in the diameter at the coarctation site (0.9 +/- 0.4 to 1.6 +/- 0.4 mm, p less than 0.01). Follow-up (6 months) has demonstrated continued gradient relief (6 +/- 9 mm Hg) and diameter increase (1.6 +/- 0.2 cm). Monitoring was performed by transesophageal echocardiography (TEE) during BCA, and before and after BCA angiography and after BCA computed tomography. In three of seven patients, immediately distal to the BCA site, intimal flaps (1-2 cm) could be detected by TEE but not by angiography or computed tomography. Follow-up TEE showed spontaneous healing in two and persistence in one patient. By TEE and computed tomography in one of eight patients during follow-up, intima and media dissection was found with pleural effusion and spontaneous healing. In one female patient, aortic dissection occurred after successful uneventful BCA, detected by TEE at the 6-month follow-up study and subsequently confirmed by biplane angiography, not detected by computed tomography and previous monoplane angiography. Because of the significant morbidity of BCA in this group of patients, its role in the management of adults with coarctation has yet to be determined. Further long-term follow-up studies will demonstrate whether the observed intima and media dissection by TEE after BCA are related to aneurysm formation.

Adult↗
PubMed1990

[Differential after care for early detection of recurrence from the radiologic viewpoint].

Diagnostic imaging plays only a minor role in the followup of local recurrencies in tumor patients. Patient history, clinical and biochemical findings as well as endoscopy are more important. The diagnosis of lymph node and other metastasis, however, requires imaging procedures. Although metastasis can be diagnosed earlier nowadays, they must still have a macroscopic size to be detected. Accuracy of the diagnostic procedures depends on the chosen "golden standard". The higher the standard, the more unreliable are imaging procedures which depending on tumor type and site of metastasis are reduced to accuracy rates of below 50%.

Combined Modality Therapy↗
PubMed1990

Fine caliber cholangioscopy.

The miniaturized diameters of endoscopes (miniendoscopes) allow percutaneous access for endoscopic visualization of the extrahepatic and intrahepatic biliary system. Practical aspects of different miniendoscopes in an experimental model are described. Clinically, fine caliber cholangioscopy is helpful in detection of retained biliary stones. Nevertheless, discrimination of benign and malignant stenosis remains difficult, and simultaneous intervention under endoscopic guidance is compromised by the low steerability of the instruments.

Animals↗
PubMed1990

[Cardiac diagnosis in the conventional chest x-ray].

Thoracic x-ray examination supplies information that is important in diagnosing heart disorders. The article presents the pathophysiological fundamentals and x-ray morphology criteria for assessing the size of the entire heart and of the individual cavities as well the cardiac functions, in a comprehensive survey.

Heart Diseases↗
PubMed1990

Radiological diagnosis of bleeding esophageal varices.

With bleeding esophageal varices radiological investigation of the underlying cause, mostly portal hypertension, is necessary. The cross-sectional imaging methods are suitable for non-invasive differentiation of the various types of underlying obstruction. Angiography may be necessary to verify the pathological findings (i.e. the extent of thrombosis), for complete demonstration of the topographical anatomy and assessment of hemodynamic parameters, and is thus an integral part of the diagnostic work-up before shunt surgery.

Angiography↗
PubMed1990

[A simple method for MRI-assisted radiotherapy planning in brain tumors].

A simple method for radiation therapy planning of brain tumors is presented. Therapy portals of midline tumors can easily be determined by comparing sagittal MRI scans with the lateral simulator radiograph. By addition of appropriately processed MR-tomograms a similar planning is possible for parasagittal tumors. Digital data exchange between different operating systems is not necessary with our simple method, problems with varying input/output standards and expensive hardware requirements are thus avoided.

Adult↗
PubMed1989

Staurosporine inhibits the respiratory burst and induces exocytosis in human neutrophils.

The protein kinase C inhibitor staurosporine influenced in different ways the functions of human neutrophils. Staurosporine prevented the enhanced protein phosphorylation in phorbol ester- and N-formylmethyionyl-leucylphenylalanine (fMLP)-stimulated cells, and was a powerful inhibitor of the respiratory burst induced by phorbol myristate acetate [IC50 (concentration causing 50% inhibition) 17 nM] and the chemotactic peptides fMLP and C5a (IC50 24 nM). It did not alter, however, the superoxide production by cell-free preparations of NADPH oxidase. Staurosporine had no effect on agonist-dependent changes in cytosolic free Ca2+ and exocytosis of specific and azurophil granules, and showed only a slight inhibition of the release of vitamin B12-binding protein induced by phorbol myristate acetate (decreased by 40% at 200 nM). On the other hand, staurosporine also exhibited neutrophil-activating properties: it induced the release of gelatinase (from secretory vesicles) and vitamin-B12-binding protein (from specific granules). These effects were protracted, concentration-dependent, insensitive to Ca2+ depletion, and strongly enhanced by cytochalasin B. Staurosporine, however, did not induce the release of beta-glucuronidase or elastase (from azurophil granules). Except for the sensitivity to cytochalasin B, these properties suggest a similarity between the exocytosis-inducing actions of staurosporine and PMA. The results obtained with staurosporine provide further evidence that different signal-transduction processes are involved in neutrophil activation, and suggest that protein phosphorylation is required for the induction of the respiratory burst, but not for exocytosis.

Alkaloids↗
PubMed1989

[Extracorporeal shockwave lithotripsy of gallstones: how many patients are suitable for it?].

The proportion of patients with gallbladder stones suitable for extracorporeal shockwave lithotripsy (ESWL) was analysed prospectively in 200 patients aged 17-76 years (62 males, 138 females) with symptomatic cholecystolithiasis. Criteria for inclusion were clinical symptoms, solitary stones (diameter 10-30 mm) or up to three stones with comparable total volume, contractile gallbladder, no calcification of stones, normal biliary tract anatomy. To check these criteria a step-by-step diagnostic procedure was instituted which consisted of history, ultrasonography with contractility test, abdominal X-ray film, computed tomography measurement of stone density, and endoscopic retrograde cholangiography. Only 19 patients fulfilled the criteria. The others had to be excluded because of history (35), stone size or number (73), impaired gallbladder contractility (27), calcified stone (30), pigment content (12), and/or biliary tract anatomy. Thus only a surprisingly small percentage (about 10%) of patients with symptomatic gallbladder stones is suitable for ESWL.

Adolescent↗
PubMed1989

[The place of bone scintigraphy in the diagnosis and follow-up of Ewing's sarcoma].

The radiological and scintigraphic findings of 26 patients with histologically proven Ewing's sarcoma were analysed. Three-phase bone scan should be done early in patients presenting with pain and normal radiographs. Perfusion and metabolism of a bone lesion can be assessed by skeletal scintigraphy. Bone metastases are first seen on bone scan. In the follow-up of the patient bone scans at regular intervals are essential to detect bone metastases and tumour recurrence. The scintigraphic findings have to be correlated with radiographs and if these are negative a short-term control is indicated. Three-phase bone scans can assess the tumours response to therapy.

Adolescent↗
PubMed1989

[The results and complications of 616 percutaneous transhepatic biliary drainages].

During nine years, percutaneous transhepatic biliary drainage was carried out 616 times on 563 patients in the Department of Radiology, University of Mainz Medical School. 50.3% were pre-operative and 39% were palliative. More than 80% were necessitated by malignant lesions. Subsequent improvements in biochemical measurements were observed in 82.4% of patients. Complications of the procedure led to the death of five patients (0.8%) and required surgery in nine patients (1.5%). The following complications were observed: biliary peritonitis in 0.6%, sepsis in 1.9%, bleeding in 1.9% and fever higher than 38 degrees C in 16.2%.

Biliary Tract↗
PubMed1989

[Digital multilayer tomography. A description of the method and initial clinical results].

A set of projection images is acquired during longitudinal tomography with an image intensifier TV system. Reconstruction of tomograms in each desired plane is achieved by shifting and summing up of the digitalized projection images. Digital multilayer and conventional film tomograms mainly of the respiratory tract and skeleton have been compared in 100 patients. Image quality is comparable with both methods. Disadvantage of digital tomography is lower spatial resolution (512 x 512 matrix size); advantages include lower radiation dose, shorter study time, and facilities of digital imaging.

Bone Diseases↗
PubMed1989

Electromagnetically generated extracorporeal shock waves for gallstone lithotripsy: in vitro experiments and clinical relevance.

First generation shock wave sources have been proved to disintegrate gallstones effectively, but they require the immersion of the patient's body in a tank of water. A recently developed second generation shock wave source (Siemens-Lithostar, Erlangen, FRG) generates shock waves electromagnetically. It presents several novel features. In particular the waterbath can be omitted and due to lower shock wave pressure general anaesthesia is not required. In vitro studies showed that 36 out of 38 gallstones (11-30 mm in diameter) could be disintegrated. Two concrements resisting lithotripsy were pure white cholesterol stones. Independent of shape, size, and composition (cholesterol or pigment) the maximum diameter of remaining fragments after lithotripsy was between 1 and 8 mm. For sufficient disintegration precise focusing (+/- 1 cm) of the stones and maximum power of the shock wave generator were required.

Cholelithiasis↗
PubMed1989

[Properties and activation mechanism of neutrophilic leukocytes].

The mechanism of neutrophil activation by chemotactic receptor agonists was studied by monitoring stimulus-induced changes in the cytosolic free calcium concentration and hydrogen peroxide formation during the respiratory burst. Two receptor-dependent signal transduction sequences were identified. One sequence depends on calcium, phospholipase C and protein kinase C, and is rate limiting, while the other is comparatively fast and appears to be calcium-independent. The present studies indicate that both sequences must act in concert to transduce receptor-mediated signals and to activate the NADPH oxidase.

Animals↗
PubMed1989

[Palpation and sonography of lymph node metastasis of the neck].

In a retrospective study, the diagnostic value and ranking of preoperative palpation and sonography for the identification of cervical lymph nodes was assessed in 130 patients with tumours of the head and neck. The diagnostic accuracy (85%) of palpation is below that of sonography (90%). The importance of sonography lies in reducing false negative findings. The increase in sensitivity (palpation 74%, sonography 90%) is, however, offset by an increase in false positive findings, i.e. by a reduction in specificity (palpation 94%, sonography 90%).

False Negative Reactions↗
PubMed1988

Two transduction sequences are necessary for neutrophil activation by receptor agonists.

The effects of 17-hydroxywortmannin (HWT), a powerful inhibitor of the respiratory burst associated with phagocytosis (Baggiolini, M., Dewald, B., Schnyder, J., Ruch, W., Cooper, P. H., and Payne, T. G. (1987) Exp. Cell Res. 169, 408-418), were studied in human neutrophils stimulated with chemotactic agonists or phorbol myristate acetate. At nanomolar concentrations HWT inhibited superoxide production and the release of granule contents induced by N-formyl-Met-Leu-Phe, C5a, platelet-activating factor, and leukotriene B4, but not by phorbol myristate acetate, indicating that it interferes with receptor-mediated activation of the neutrophils, without directly affecting protein kinase C (Ca2+/phospholipid-dependent enzyme), the NADPH-oxidase, or the process of granule exocytosis. Moreover, HWT did not influence agonist-induced [Ca2+]i changes, indicating that it does not interfere with the function of agonist receptors, G-proteins or the phosphatidylinositol-specific phospholipase C. By studying the effect of HWT on the respiratory burst elicited in normal and Ca2+-depleted cells by combined stimulation with N-formyl-Met-Leu-Phe and phorbol myristate acetate, evidence was obtained that two transduction sequences, both of which are G-protein-dependent, are necessary for the induction of the response by receptor agonists. One sequence is Ca2+-dependent, HWT-insensitive, and leads to activation of protein kinase C, the other is Ca2+-independent and HWT-sensitive. Ca2+ depletion, which blocks the first, and HWT, which blocks the second, can be used to show that both processes must be functional for the transduction of agonist signals into a respiratory burst response.

Androstadienes↗