Search PubMed⌕ Search

Biomedical subjects

M Thelen

Publications and source records attributed to M Thelen.

At least 289 records · Page 16Linked to original sources
PubMed1991

Graves ophthalmopathy: role of MR imaging in radiation therapy.

Twenty-three patients with Graves ophthalmopathy who underwent radiation therapy were monitored by means of magnetic resonance (MR) imaging. T2 relaxation times of extraocular muscles and orbital fat, areas of extraocular muscles, and degree of exophthalmos were measured by means of MR imaging at the beginning, at the end, and 3 months after completion of radiation therapy. As a result, patients with primarily elevated T2 times of extraocular muscles showed a better therapy response regarding muscle thickening than patients with primarily normal T2 times. Elevated T2 times, which probably represent acute inflammatory changes, were markedly decreased at the end of therapy. Therefore, quantitative MR imaging favors the choice of anti-inflammatory therapy regimens in patients with elevated T2 times of extraocular muscles. However, the clinical response (activity scores) to the low-dose treatment protocol that was used did not correlate well with primarily elevated T2 times. Furthermore, T2 times increased again after cessation of therapy. Whether a higher radiation dose or a different fractionation scheme leads to better results must be clarified by means of further study.

Adult↗
PubMed1991

[Computerized tomography differentiation of pigment and cholesterol bile duct calculi].

Successful oral litholytic and other non-operative therapies of gallstones require exact determination of the stone components. Since computed tomography (CT) provides highly sensitive measurement of density, we performed a study to evaluate whether CT measurement of stone density allows to predict the composition of radiolucent gallstones. 28 patients presenting with 29 radiolucent gallbladder (n = 17) or common bile duct stones (n = 12) were included. Prior to operative or endoscopic therapy the attenuation values (Hounsfield Units/HU) were assessed in vivo by CT under standardised conditions (Somatom II; 125 KV; 130 mAs). After surgical or endoscopic stone removal the concrements were dehydrated, homogenised and then analysed by infrared spectroscopy. 18 cholesterol and 11 pigment stones could be identified. The attenuation values (Hounsfield Units) of cholesterol stones amounting to 28-98 HU (48.7 +/- 4.4 HU) differed significantly (p less than 0.001) from pigment stones (90-120 HU/105.5 +/- 2.8 HU). We conclude that computed tomography provides exact discrimination between cholesterol and pigment stones in vivo. Since only cholesterol stones can be dissolved by cheno/ursodeoxycholic acid we recommend to measure the radiodensity of gallstones by CT prior to any litholytic therapy.

Bile Pigments↗
PubMed1990

Activation of protein kinase C results in the displacement of its myristoylated, alanine-rich substrate from punctate structures in macrophage filopodia.

The myristoylated, alanine-rich C kinase substrate (MARCKS) is a prominent substrate for protein kinase C (PKC) in a variety of cells, and has been implicated in diverse cellular processes including neurosecretion, fibroblast mitogenesis, and macrophage activation. In macrophages that have spread on the substratum, MARCKS has a punctate distribution at the cell-substratum interface of pseudopodia and filopodia. At these points, MARCKS co-localizes with vinculin and talin. Activation of PKC with phorbol esters results in the rapid disappearance of punctate staining of MARCKS, but not vinculin or talin, and is accompanied by cell spreading and loss of filopodia. The morphological changes and disappearance of punctate staining follow a time-course that closely approximates both the PKC-dependent phosphorylation of MARCKS, and its phosphorylation-dependent release from the plasma membrane. Our results suggest a role for PKC-dependent phosphorylation of MARCKS in the regulation of the membrane cytoskeleton.

Animals↗
PubMed1990

[Focal liver lesions as incidental findings. 2: Diagnostic procedures in sonographically homogeneous echo-rich, echo-poor or inhomogeneous lesions].

Hemangioma is one of the most common incidental findings in the ultrasonographic image. In 80% to 90% of the cases, the hemangioma presents as a homogeneous lesion in the US image. In asymptomatic patients and a lesion diameter of less than 2 cm, further clarification additional to ultrasonography is not necessary. Major differential diagnoses are focal nodular hyperplasia, metastasis, hepatocellular carcinoma and liver cell adenoma. With exceptions, the biological significance of echo-poor or inhomogeneous lesions cannot be established on the basis of the US image. In such cases, additional diagnostic procedures are required.

Angiography↗
PubMed1990

[Focal liver lesion as an incidental finding. 1: Diagnostic management--procedure in sonographically echo-free tumors].

The spread of diagnostic ultrasound has led to an increase in the incidental detection of lesions of the liver in patients with unrelated symptoms and no history of tumor disease. In this article, suggestions are made on how to proceed with the further diagnostic workup of such patients. In part 1 these suggestions are aimed at identifying patients who might benefit from further investigation, while at the same time avoiding unnecessary procedures.

Biopsy↗
PubMed1990

Reconstitution of cell-free NADPH-oxidase from human monocytes and comparison with neutrophils.

A rapid centrifugal elutriation procedure was developed to prepare high amounts of pure human blood monocytes. After disruption by nitrogen cavitation, a cytosol and a membrane fraction were obtained by sucrose-Percoll density centrifugation. The plasma membrane fraction contained cytochrome b558 and was free of microsomal or mitochondrial cytochromes as determined by low-temperature absorbance spectroscopy. Cell-free NADPH-oxidase activity from monocytes and neutrophils was reconstituted with cytosol and membranes in the presence of sodium dodecyl sulphate. By comparison with neutrophils, the cell-free NADPH-oxidase from monocytes showed a two- to threefold lower specific activity. The NADPH-oxidase was reconstituted with neutrophil membranes and monocyte cytosol, and vice versa. The Km for NADPH was always lower when monocyte cytosol was used. These experiments indicate that the membrane-bound components of the NADPH-oxidase from neutrophils and monocyte are similar and that levels of NADPH-oxidase components in the cytosols differ. Interferon gamma-treatment of the monocytes had no effect on the specific activity of the cell-free NADPH-oxidase.

Cell Membrane↗
PubMed1990

[Radiotherapy in HIV positive patients].

HIV-positive Patients often suffer from the symptoms of accompanying diseases. Palliative radiation therapy of associated tumors leads to an improvement of the patient's condition. Particularly skin tumors, which give rise to pronounced itching and ulcerating, are eliminated fast and safe by radiation therapy. Between 1984 and 1988, 6 HIV patients with Kaposi's sarcoma at different sites, and one HIV-patient with non-Hodgkin's lymphoma were treated by radiation therapy. Depending on tumor site, photons or fast electrons were used. Cosmetic results were satisfying or even excellent in all patients. With one exception complete local tumor control was obtained. Side effects leading to a peace of treatment did not occur.

Combined Modality Therapy↗
PubMed1990

Cerebral and spinal MR-findings in patients with postrepair myelomeningocele.

In 114 patients with postrepair myelomeningocele MRI of the spine was performed. Tethered cord (89%) and associated malformations (syrinx, lipoma etc.) (33%) were the most important findings. Additional MRI scans of the head (44 patients) revealed numerous further anomalies. Arnold Chiari malformation was found in 76% of the patients (ACM I:32%, ACM II:44%). In the ACM II group compression of lower cranial nerves, brain stem, and cerebellum can lead to considerable neurologic symptoms. Therefore in patients with progressive neurologic dysfunction a complete investigation of the whole spine and brain is necessary. MRI proves to be the diagnostic procedure of choice in patients with dysraphic myelodysplasia.

Adolescent↗
PubMed1990

[Quantitative determination of cerebral perfusion using digital subtraction angiography (DSA)].

In a search for a reliable and relatively non-invasive method for quantifying cerebral perfusion, we examined the possible role of DSA. By using special software, it is possible to demonstrate vascular morphology and obtain functional data concerning blood flow. Regions of interest are used for obtaining time-density curves and these are evaluated by a formula designed by Meier and Zierler. Perfusion through the arterial territory in both cerebral hemispheres was correlated with the clinical symptoms of the patients and with the morphological findings. Difficulties and problems are described and discussed.

Angiography, Digital Subtraction↗
PubMed1990

[Sonography of bone metastases--its place in comparison with computed tomography and conventional x-ray diagnosis].

The value of CT, conventional radiography and ultrasound was compared in 40 patients with 52 skeletal metastases. For superficial lesions, the combination of sonography and conventional radiography was equivalent to CT in showing the extent of bone destruction and soft tissue involvement. As expected sonography was unsatisfactory for deeper lesions. Sonography can provide useful information for planning radiation therapy for superficial lesions, but it does not replace conventional radiography.

Bone Neoplasms↗
PubMed1990

[Cervical lymph node metastases: a histologically controlled comparison of palpation, sonography and computed tomography].

Sonography and CT were used pre-operatively for lymph node staging in patients with head and neck malignancies. The accuracy of the imaging methods surpassed that of palpation (palpation 85%, CT 85%, sonography 90%). Sensitivity was significantly increased from 74% (palpation) to 84% (CT) and 90% (sonography), ie. there was a reduction in false negative findings. Size of lymph nodes was not closely correlated with metastatic involvement. Reactively enlarged lymph nodes were more easily defined by CT and sonography than by palpation. This reduced the specificity of sonography (90%) and of CT (86%) compared to palpation (94%).

Carcinoma, Squamous Cell↗
PubMed1990

[Functional angiography of the arteries near the knee joint: consequences for stent implantation?].

Angiographic studies of the arteries adjoining the knee in 25 patients show extensive kinking and stenoses of the popliteal artery and less frequently of the distal femoral artery during flexion of the knee joint. This is due to the loss of elasticity with increasing age forcing the vessel into a tortuous course during shortening of the pathway of the popliteal artery with knee flexion. Independent of the principle of the different stents available they probably will not increase the contractility of the stented vessel in the longitudinal axis. It is to expect that after implantation of stents into the popliteal artery kinking will occur predominantly in the original segments of the vessel and at the transitions to the stented segments leading to intimal damage by shear forces thus propagating local progress of atherosclerosis.

Adult↗
PubMed1990

[Clinical experience with the Kensey catheter system--complications and results].

Fifteen procedures have been carried out in 14 patients using the Kensey rotation angioplasty system. Sixteen occlusions of the superficial femoral artery, with an average length of 10.2 cm (3 to 24 cm) and one artery with multiple stenoses were treated. The following results were obtained: creation of a lumen, with subsequent balloon dilatation in eight out of fifteen procedures; in two patients the vessels were occluded shortly after the procedure, due to complications (one obstructive plaque and one haematoma); five perforations, three dissections and one peripheral embolus. The total complication rate was 11 out of 15 cases, clinical improvement was obtained in six out of 15 cases.

Aged↗
PubMed1990

[The behavior of collaterals during percutaneous transluminal angioplasty].

The fate of 106 collaterals was investigated following percutaneous transluminal dilatation of 113 stenoses and occlusions. Following dilatation, 78% of collaterals were unchanged and 22% could no longer be demonstrated. The success of the dilatation had no bearing on the fate of the collaterals. Collaterals beginning or ending in a dilated portion of vessel disappeared more frequently (30%) than the others (11%). Following five dilatations, some vessels were demonstrated in the area of stenosis, which had not been demonstrated previously. Evidently local events, such as displacement of arteriosclerotic plaques may lead to occlusion or reopening of vessels. Remaining collaterals may be of great importance in saving a limb if there is an acute occlusion complicating a dilatation.

Angioplasty, Balloon↗
PubMed1990

[The imaging diagnosis of peritoneal carcinosis].

Two hundred and eighty-seven radiological and sonographic examinations in 142 patients with confirmed peritoneal carcinosis were evaluated retrospectively. The examinations included abdominal films (19), infusion urograms (20), contrast examinations of the intestine (26), small bowel enemas (2), double-contrast examinations of the colon (40), demonstrations with water-soluble contrast (6), sonographies (80) and CTs (96). CT and colonic double-contrast studies were complementary and valuable methods for diagnosing peritoneal carcinosis and should both be used.

Abdomen↗
PubMed1990

Tumor necrosis factor alpha modifies agonist-dependent responses in human neutrophils by inducing the synthesis and myristoylation of a specific protein kinase C substrate.

Tumor necrosis factor alpha (TNF-alpha) and bacterial lipopolysaccharide (LPS) induce the synthesis and cotranslational myristoylation of an 82-kDa specific protein kinase C substrate in human neutrophils. The myristic acid is covalently bound via a hydroxylamine-resistant amide linkage to the N-terminal glycine of the protein. The isoelectric point of the protein is at pH 4.6. The protein is rapidly phosphorylated when neutrophils are stimulated with chemotactic agonists or with phorbol 12-myristate 13-acetate, an activator of protein kinase C, and displays two characteristic phosphopeptides in one- and two-dimensional separation systems. Identical phosphopeptides were detected when the 82-kDa protein was phosphorylated in vitro with purified kinase C. The 82-kDa protein was immunoprecipitated by a polyclonal antiserum raised against the 87-kDa specific protein kinase C substrate from bovine brain. From these biochemical and immunological criteria it is concluded that the 82-kDa protein is the human neutrophil homolog of MARCKS, the myristoylated, alanine-rich C kinase substrate previously described in bovine and rat brain and in murine fibroblasts and macrophages. TNF-alpha and LPS prime human neutrophils for potentiated protein kinase C-dependent responses such as the respiratory burst and exocytosis. Consistent with this, these mediators do not induce the phosphorylation of MARCKS but prime the neutrophils for enhanced phosphorylation of this protein when the cells subsequently encounter activators of protein kinase C. This increase in MARCKS phosphorylation can be explained by the elevated levels of the protein observed in TNF-alpha- or LPS-treated neutrophils. Indeed, MARCKS constitutes 90% of all proteins synthesized in response to TNF-alpha or LPS. These data strongly suggest that MARCKS acts as a critical effector molecule in the transduction pathway of these important inflammatory mediators.

Colony-Stimulating Factors↗
PubMed1990

Analysis of radiolucent gallstones by computed tomography for in vivo estimation of stone components.

Successful oral litholytic and other nonoperative therapies of gallstones require exact determination of the stone components. Since computed tomography (CT) provides highly sensitive measurement of density, we performed a study to evaluate whether CT measurement of stone density allows a prediction of the composition of radiolucent gallstones. Twenty-eight patients presenting with 29 radiolucent gallbladder (n = 17) or common bile duct stones (n = 12) were included. Prior to operative or endoscopic therapy the attenuation values (Hounsfield Units, HU) were assessed in vivo by CT under standardized conditions (Somatom II, 125 KV, 130 mAs). After surgical or endoscopic stone removal the concrements were dehydrated, homogenized and then analysed by infra-red spectroscopy. The previously measured Hounsfield units were not known to the investigator. Eighteen cholesterol and 11 pigment stones could be identified. The attenuation values (Hounsfield units) of cholesterol stones amounting to 28-98 HU (48.7 +/- 4.4 HU) differed significantly (P less than 0.001) from pigment stones (90-120 HU/105.5 +/- 2.8 HU). We conclude that computed tomography provides exact discrimination between cholesterol and non-cholesterol stones in vivo. Since only cholesterol stones can be dissolved by cheno- and ursodeoxycholic acid we recommend measurement of the radiodensity of gallstones by CT prior to any litholytic therapy. Furthermore the prediction of the stone composition facilitates the decision on extracorporeal shock wave lithotripsy and the selection of specific solvents for contact lysis via a nasobiliary probe.

Bilirubin↗