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Biomedical subjects

M Thelen

Publications and source records attributed to M Thelen.

At least 271 records · Page 15Linked to original sources
PubMed1992

[Computerized tomography analysis of gallstones: soon an essential diagnosis before nonsurgical gallstone therapy?].

Successful application of non operative procedures for gallstone therapy are limited on cholesterol stones. Therefore reliable therapeutic analysis of stone components is mandatory for planning of an adequate therapy. Computed tomographic gallstone analysis is considered to improve selection of patients significantly. However, standardized conditions for investigation of patients are not yet established. It is suggested that computerized tomography should be performed using 4 mm slides, standardized position of patients and a phantom, which allows calibration of different CT-machines.

Bile Pigments↗
PubMed1992

[Lobular carcinoma of the breast in magnetic resonance tomography. A case report].

The invasive lobular carcinoma of the breast, the incidence of which is 10-15 per cent, occupies a special position in respect of histological differentiation and biological behaviour. No MR signal enhancement was seen after contrast medium application in the tumoral tissue in the case described here, namely, an invasive lobular carcinoma of the breast of 2 cm size. Hence, it is not always possible to exclude with absolute certainty the presence especially of an invasive lobular carcinoma of the breast in the absence of contrast medium uptake.

Breast Neoplasms↗
PubMed1992

[Diagnostic goals in aortic dissection. Value of transthoracic and transesophageal echocardiography].

The combination of different ultrasound techniques like transthoracic, suprasternal, subcostal and transesophageal echocardiography have a high sensitivity and specificity in the diagnosis of aortic dissection. The limitation of this combined ultrasound technique is related to the visualization of the ascending part of the aortic arch which, cause of the interposition of the trachea, can not be visualized completely. The beginning or the end of a dissection in this part of the aorta may be misinterpreted. False negative results are rare. False positive results due to artefacts resulting from reverberations in an ectatic ascending aorta have to be taken into account. The most important diagnostic aims in acute or chronic aortic dissection can be described: 1. confirmation of the diagnosis by visualization of the intima membrane, 2. the differentiation of the true and false lumen depending on visualization of spontaneous echocardiographic contrast thrombus formation, slow or reduced reversed flow, systolic diameter reduction and signs of entry jet into the false lumen, 3. detection of intimal tear, demonstrating communication by two-dimensional or color Doppler echocardiography, 4. determination of the extent of the dissection with classification according to DeBakey type I, II and III or Stanford A and B with differentiation to communicating or non-communicating dissection, antegrade or retrograde dissection limited to the descending aorta or expanding to the ascending aorta, 5. detection of wall motion abnormalities as a sign of preexisting coronary artery disease or myocardial ischemia due to ostium occlusion by an intimal flap, coronary artery rupture or collapse of the true lumen during diastole, 6. detection and grading of aortic insufficiency, 7. detection of side branch involvement by suprasternal, subcostal and abdominal sonography, which will gain the information which side can be chosen for cannulation or catheterization at the femoral artery, 8. detection of pericardial pleural effusion and mediastinal hematoma as a sign of emergency as rupture can occur within minutes. Without surgical intervention have be performed. Based on these informations, surgery can be performed in all acute situations in type A dissection without further investigations. This decision is particularly important in patients with signs of emergency like pericardial or pleural effusion or mediastinal hematoma.

Aortic Dissection↗
PubMed1992

More on AuD.

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American Speech-Language-Hearing Association↗
PubMed1991

[Ambulatory angiography].

Outpatient angiography is justified in selected cases; patients with risk factors must be excluded. The examination should be performed as atraumatically as possible. After angiography, the patient should be kept under observation for at least 6 hours, since most complications occur during or shortly after the intervention. Only vary rarely do complications develop after the patient has been discharged, the most serious being late hemorrhage. Facilities for rapid treatment must be provided.

Ambulatory Care↗
PubMed1991

Regulation by phosphorylation of reversible association of a myristoylated protein kinase C substrate with the plasma membrane.

Protein kinase C (PKC) transduces receptor-mediated signals by phosphorylating membrane-bound substrates which then act as effectors of specific cellular responses. The myristoylated alanine-rich C kinase substrate (MARCKS) is a specific PKC substrate which has been implicated in macrophage activation, neuro-secretion and growth factor-dependent mitogenesis. Myristoylation of MARCKS is required for effective binding to the plasma membrane where it colocalizes with PKC. Here we report that PKC-dependent phosphorylation displaces MARCKS from the membrane and that its subsequent dephosphorylation is accompanied by its reassociation with the membrane. This cycle of phosphorylation-dependent membrane attachment and detachment of a myristoylated protein represents a novel mechanism of reversible membrane targeting. As MARCKS is a calmodulin- and actin-binding protein (ref. 8, and J. Hartwig et al., manuscript submitted), the cycle of membrane attachment/detachment represents a mechanism through which PKC might reversibly regulate actin-membrane interaction.

Adenosine Triphosphate↗
PubMed1991

[Interventional angiology in the area of the thigh. Percutaneous balloon dilatation, new procedures of recanalization, stents].

The major technique of interventional angiology of the arteries of the thigh is percutaneous balloon dilatation (angioplasty). In the case of short stenoses and occlusions, the primary results and long-term success of these techniques are very good. In order to be able to successfully treat long, highly calcified, eccentric and fresh lesions using the percutaneous approach, numerous new procedures have been developed. These include local fibrinolysis, aspiration of thromboembolic material, ablation of atherosclerotic plaques using an endovascular knife, the drilling open of occlusions, the use of the laser, and implantation of vascular endoprostheses.

Angioplasty, Balloon↗
PubMed1991

[Nonsurgical recanalization of tibial arteries. Balloon dilatation, local fibrinolysis and aspiration embolectomy].

To date, percutaneous angioplasty has only rarely been employed to recanalize arteries in the lower leg. In almost all such patients, the limb has been at risk of being amputated. Since the introduction of special thin-caliber balloon catheters and concomitant drug therapy to prevent vascular spasms and thromboses, results have been markedly improved. In the case of fresh occlusions, local fibrinolysis with percutaneous aspiration embolectomy is employed.

Angioplasty, Balloon↗
PubMed1991

GM-1, a clone of the monoblastic phagocyte U937 that expresses a large respiratory burst capacity upon activation with interferon-gamma.

The human cell line U937 was cloned and screened for the responsiveness to interferon-gamma (INF-gamma). The selected subclone, named GM-1, expressed a high density of IFN-gamma receptors and showed HLA typing similar to that of the parental line but was devoid of the Y chromosome. GM-1 cells display a promyeloid phenotype as revealed by flow cytometry using a panel of murine antibodies. Following treatment with IFN-gamma GM-1 cells differentiated to a more mature monocyte stage and acquired the capacity to mount a respiratory burst. After treatment with differentiation promotors, such as phorbol 12-myristate 13-acetate (PMA), dimethyl sulfoxide (DMSO), and retinoic acid, GM-1 showed a more limited respiratory burst capacity. Superoxide release in IFN-gamma-activated cells was stimulated with f-Met-Leu-Phe, C5a, or PMA. The development of the respiratory burst capacity was accompanied with the expression of cytochrome b558, a component of the phagocyte NADPH-oxidase. GM-1 cells are useful for the study of the effects of IFN-gamma on the respiratory burst. They are more sensitive and yield a more homogenous response to IFN-gamma than U937 cells. The phenotype of GM-1 cells was stable for more than 5 years.

Antigens, CD↗
PubMed1991

MRI-assisted radiation therapy planning of brain tumors--clinical experiences in 17 patients.

A new and simple method for precise determination of lateral opposed treatment portals was developed and used in 17 patients. Compared to CT, MRI led to significant changes of portals in 59% (10/17) of cases. Individual shielding blocks could be precisely designed by use of our new method. MRI is the procedure of choice in local radiation therapy planning of brain tumors.

Adolescent↗
PubMed1991

[Regional lymph node metastases in malignant tumors of the head and neck: value of diagnostic procedures].

Sonography and computed tomography are used in staging of lymph nodes of patients with head and neck cancer. The accuracy of sonography (90%) and computed tomography (85%) is comparable or better than the palpatory accuracy (85%). The better delineation of reactive swollen cervical nodes leads to a higher sensitivity of sonography (90%) and computed tomography (84%) versus palpation (74%), but a lower specifity (palpation 94%, sonography 90%, computed tomography 86%). A literature survey shows that sonography, computed tomography and magnetic resonance imaging of cervical lymph nodes are comparable good methods.

Carcinoma, Squamous Cell↗
PubMed1991

[Diagnosis of pleural effusions and atelectases: sonography and radiology compared].

In a prospective study it was shown that chest ultrasonography is superior to conventional x-ray diagnosis of recumbent patients in diagnosing pleural effusion and lung atelectasis. In 110 supine radiographs we found a sensitivity of 47% and a specificity of 71% for right pleural effusions and a sensitivity of 55% and a specificity of 93% for left pleural effusions in comparison to 110 sonographic examinations. The results of supine radiographs in detection of atelectasis were less efficient: sensitivity for the right side: 7%; sensitivity for the left side: 13.5%. Hence, the knowledge of chest ultrasonographic diagnosis can improve the interpretation of supine radiographs.

Critical Care↗
PubMed1991

[Intravascular sonography: initial clinical results].

Intravascular ultrasound is a new diagnostic modality which, for the first time, provides high resolution images of the vessel wall. 91 intraluminal ultrasound studies were performed in 50 patients during the course of 55 diagnostic and therapeutic catheterizations. A F-6 ultrasound catheter (20 MHz) was used. The method is an easily and rapidly performed addition to angiography. Changes in vessel walls (arteriosclerosis, dissection, tumour infiltration) can be readily diagnosed and their extent can be accurately described. The ability to determine luminal cross sectional area is particularly helpful for planning and performing therapeutic interventions.

Adult↗
PubMed1991

[Computed tomography following extracorporeal shockwave lithotripsy (ESWL) of the kidneys. I: Correlation with acute histopathological findings in experimental animals].

In an experimental study on pigs, 28 stone-free kidneys were treated with a second generation lithotripter. Histologically, acute bleeding was seen after ESWL in 23 (82%) of the 28 treated kidneys. CT studies before and after contrast were correct in 20/28 (74%) cases. It was shown that extracorporeal shock waves cause renal bleeding that is only partially detected by computed tomography. It can be concluded that the CT findings seen in a high percentage of renal stone patients after ESWL represent bleeding. The incidence of renal bleeding after ESWL and thus the possible risk of hypertension has obviously been underestimated so far in clinical studies.

Animals↗
PubMed1991

[Early and late results of percutaneous transluminal angioplasty (PTA) in diabetic patients].

Results of 127 iliac and femoropopliteal transluminal angioplasties in 97 diabetic patients are presented. Patients who had undergone iliac (n = 70), femoral (n = 41), and popliteal (n = 16) angioplasties for stenoses up to 15 cm long were followed up for 6-60 months. In diabetic patients presenting with only claudication or adequate runoff, the 5-year iliac patency rate was 76% and the femoral patency rate was 60%; these results were comparable with those found in non-diabetic patients. For limb salvage, 3-year patency rates were 66% for iliac, 37% for femoral, and 37% for popliteal angioplasties, and 5-year patency rates were 29% for iliac, 7% for femoral, and 0% for popliteal angioplasties. Our findings suggest that the overall decreased PTA success rates typically associated with diabetes are due to the larger percentage of these patients who present with symptoms of severe peripheral vascular disease and not to the presence of diabetes per se.

Adult↗
PubMed1991

[Percutaneous ureteral occlusion. Methods, results, problems].

One hundred and nineteen transrenal occlusions of 77 ureters were carried out in 71 patients. Thirty-one ureters were occluded by means of glue and in 21 Gianturco coils were introduced at the same time. Forty-six ureters were occluded by means of disposable silicone-filled latex balloons. Seventeen out of 31 ureters treated with glue (55%) and 32 out of 46 ureters with balloons (70%) were permanently occluded. On 42 occasions, re-occlusions had to be carried out, the average period from the initial occlusion being 2.5 weeks for glue and 19.5 weeks for balloons. In nine out of the 119 ureteric occlusions (7.5%), there were mild complications; these were easily treated and were of no consequence to the patient.

Adult↗
PubMed1991

[Computed tomography after extracorporeal shockwave lithotripsy (ESWL) of the kidneys. II. A correlation with the histopathologic findings 3 weeks later in an animal experiment].

In a pig model, 13 kidneys were treated with a second generation lithotripter and examined by CT immediately and three weeks after ESWL. 9 (69%) acute traumatic lesions were seen in CT without, and 10 (77%) in CT with contrast in the 13 treated kidneys. After 3 weeks only 1 residual lesion persisted in CT contrast studies. On the histopathologic specimens residuals of bleeding were found in 3 (23%) of the 13 kidneys treated, which could not be seen in CT studies. CT is accurate in monitoring acute traumatic renal lesions after ESWL, but appears less reliable in chronic ones. Three weeks after ESWL traumatic renal lesions show marked regression.

Animals↗