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Biomedical subjects

M Thelen

Publications and source records attributed to M Thelen.

At least 343 records · Page 19Linked to original sources
PubMed1987

Diagnosis of aortic dissection: the value of transesophageal echocardiography.

Using the transesophageal approach the descending part of the aorta can be imaged by two-dimensional enchocardiography in cross sections comparable to computer tomograms. The value of combined transesophageal and transthoracic echocardiography was evaluated in 53 patients who were studied consecutively from 1983 to 1986 with symptoms of aortic dissection and compared with computed tomography, angiography, surgery and/or autopsy. In all patients the transthoracic aorta could be visualized and the dissection could be classified according to DeBakey: in 9 of 29 patients (34%) type I dissection, in 4 (14%) type II dissection and in 16 (55%) type III dissection was found. Operation was carried out because of acute symptoms in 11 of the 29 patients, and 3 additional patients died before operation. In 24 patients aortic dissection could be ruled out. A sensitivity of 97% for transthoracic and transesophageal echocardiography, of 80% for computed tomography and of 78% for angiography was calculated. The specificity for echocardiography was 100%, for computed tomography 100% and for angiography 95%. The positive predictive accuracy for echocardiography and computed tomography was 100% and 95% for angiography. The negative predictive accuracy for echocardiography was 96%, for computed tomography 77% and for angiography 79%. In no patient was an aortic dissection found by computed tomography or angiography which was not detected by echocardiography. In 1 patient with a large ectasia of the aorta ascendens aortic dissection was overlooked as retrospective analysis demonstrated. Signs of aortic insufficiency and pericardial effusion were detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Local fibrinolytic therapy of vascular occlusions in the pelvic-leg area and the upper extremity].

Seventy-three patients with vascular occlusions in the pelvis or lower limbs and three patients with upper limb lesions were treated by local low dose fibrinolysin, with strict control of any possible bleeding tendencies. Adequate recanalisation was obtained in 56 patients (73.6%). In ten patients, the occlusion recurred while the patient was still in hospital. After four to six months, 37 of the 56 (67%) of the vessels were still patent. In 18 patients, peripheral emboli resulted in some deterioration, but in 15 of these cases this could be treated successfully by operation. The methods and indications of local fibrinolysis therapy and the problems associated with it are discussed.

Adult↗
PubMed1987

[Characterization of cerebral blood flow by determining the vascular mean transit time of brain tissue using DSA].

By using a recently developed algorithm it is possible to quantify the dynamic information of a DSA sequence of the brain. The theory of algorithm allows to calculate vascular mean transit from time density curves. The algorithm minimizes the problems of densitometry with regard to "quantitative DSA". There is a strong correlation between vascular mean transit times and cerebral blood flow values, and therefore the results for mean transit times also correspond to the results obtained for cerebral blood flow. By computerized postprocessing of DSA-images it is possible to generate functional images of the brain with a spatial resolution that had not been attainable so far. The images represent the distribution pattern of reverse vascular mean transit times. The results from 36 patients with proven stenoses of the cervical vessels are reported.

Carotid Artery Diseases↗
PubMed1987

[Computerized tomography of the thorax in intensive care patients].

Thoracic CT for patients in intensive care is cumbersome but provides important additional information in the presence of complicated lung changes. Total opacification of a lung field visualised on conventional portable films may be due to infiltration and/or fluid and/or collapse by using the clinical information in conjunction with densitometric measurements. CT may help in the differentiation of pulmonary oedema, particularly in the presence of ARDS and its complications. It is also possible to accurately localise abscesses and empyemas in the presence of extensive consolidation. This makes it possible to drain abscesses or empyemas, or pleural fluid in unusual situations, which has become loculated, or to aspirate a pneumothorax.

Adult↗
PubMed1987

[Focal nodular hyperplasia of the liver in 930 patients].

Analysis of 930 patients with focal nodular hyperplasia of the liver (FNH), including 23 seen by the authors, showed the following results: 82.2% of patients were female, 37.8% of these had taken female steroidal hormones. There was no preference for a particular lobe of the liver. 57.7% of FNH were subcapsular, 33.7% were intrahepatic and 8.8% were pedunculated. Average size was 5.9 cm, 80.8% of the patients were asymptomatic. In 93.5% (115 out of 123) a space-occupying lesion in the liver could be demonstrated by sonography. In 13%, second or multiple tumours were missed by sonography. CT without enhancement demonstrated FNH in 90.4% (94 out of 104 patients). A rapid, marked increase in density after contrast was seen in 64 out of 68 lesions (94.1%). Colloid scintigraphy showed normal uptake in 34.9% of patients. Hepato-biliary functional scintigraphy demonstrated 32 out of 35 lesions (91.4%). In 97.3% (183 out of 188) FNH was demonstrated by angiography, in 95.4% as a highly vascular tumour.

Adolescent↗
PubMed1987

[Liver CT with portal vein administration of a contrast medium].

Contrast administration through the superior mesenteric or splenic arteries provided additional information in 22 out of 31 patients, when compared with intravenous contrast bolus for CT of the liver. In 11 patients, the demonstration of a tumour lead to a change in treatment. False positive findings occurred in four of the 31 patients. In 2 patients intrahepatic lesions were overlooked, but were found during angiography carried out at the same examination. The diagnosis of intrahepatic space-occupying lesions is discussed as well as the CT appearances of portal-venous liver perfusion.

Adult↗
PubMed1987

UDP-Glucose: (1-->3)-beta-Glucan Synthases from Mung Bean and Cotton: Differential Effects of Ca and Mg on Enzyme Properties and on Macromolecular Structure of the Glucan Product.

A re-examination of the kinetic properties of UDP-glucose: (1-->3)-beta-glucan (callose) synthases from mung bean seedlings (Vigna radiata) and cotton fibers (Gossypium hirsutum) shows that these enzymes have a complex interaction with UDP-glucose and various effectors. Stimulation of activity by micromolar concentrations of Ca(2+) and millimolar concentrations of beta-glucosides or other polyols is highest at low (<100 micromolar) UDP-glucose concentrations. These effectors act both by raising the V(max) of the enzyme, and by lowering the apparent K(m) for UDP-glucose from >1 millimolar to 0.2 to 0.3 millimolar. Mg(2+) markedly enhances the affinity of the mung bean enzyme for Ca(2+) but not for beta-glucoside; with saturating Ca(2+), Mg(2+) only slightly stimulates further production of glucan. However, the presence of Mg(2+) during synthesis, or NaBH(4) treatment after synthesis, changes the nature of the product from dispersed, alkali-soluble fibrils to highly aggregated, alkali-insoluble fibrils. Callose synthesized in vitro by the Ca(2+), beta-glucoside-activated cotton fiber enzyme, with or without Mg(2+), is very similar in size to callose isolated from cotton fibers, but is a linear (1-->3)-beta-glucan lacking the small amount of branches at C-0-6 found in vivo. We conclude that the high degree of aggregation of the fibrils synthesized with Mg(2+)in vitro is caused either by an alteration of the glucan at the reducing end or, indirectly, by an effect of Mg(2+) on the conformation of the enzyme. Rate-zonal centrifugation of the solubilized mung bean callose synthase confirms that divalent cations can affect the size or conformation of this enzyme.

Journal Article↗
PubMed1987

Detection of aortic dissection by transoesophageal echocardiography.

The diagnostic value of a combination of transoesophageal and transthoracic echocardiography was evaluated in 21 patients with dissection of the aorta. The results were compared with those of computed tomography, aortography, and with findings at operation or necropsy or both. Transthoracic echocardiography identified three of the four patients with type I dissection, two of the five patients with type II dissection, and one of the 12 patients with type III dissection. When transoesophageal echocardiography was used as well the degree of aortic dissection was identified correctly in all 21 patients. In one patient with type I and in eight patients with type III dissection spontaneous echocardiographic contrast with a mural thrombus within the false lumen could be detected. Computed tomography was unable to demonstrate an intimal flap in one of two patients studied with type I dissection, in two of three patients with type II dissection, and in one of nine patients with type III dissection. Aortography was negative in one of two patients studied with type I dissection, two of four patients with type II dissection, and in one of eight patients with type II dissection. The whole thoracic aorta can be imaged by a combination of transthoracic and transoesophageal echocardiography. The addition of transoesophageal echocardiography to transthoracic echocardiography improves the recognition of aortic dissection. Furthermore, this examination can be performed at the bedside and the findings can be used as a basis for treatment.

Adult↗
PubMed1987

[Ultrasonic diagnosis, computed tomography and lymphography of retroperitoneal lymphomas--re-evaluation of lymphography].

Regarding the present results and the review of literature, we are of the opinion that negative attitude towards lymphography is not justified. In diagnostic procedure, priority is given to sonography and computed tomography because of their non-invasiveness. Lymphography is indispensable in all cases where sonography or computed tomography show negative findings and where the therapy planning depends on evidence or exclusion of retroperitoneal lymphomas. In general the combination of both computed tomography and lymphography is the most sensitive and consequently, the safest method in the diagnosis of retroperitoneal lymphomas.

Evaluation Studies as Topic↗
PubMed1987

["False" sinking abscess].

In a 43 year old man with an inguinal abscess a paravertebral soft tissue swelling suggested a gravitation abscess. On CT only a retrocrural fat accumulation was identified.

Abscess↗
PubMed1987

[Reuse of angiography catheters. Results and discussion of the present state of knowledge].

The re-use of angiographic catheters after cleansing and sterilization with ethylene oxide has received increasing attention, primarily because of cost considerations. However, there are various risks in this common practice, mainly because the principles of maintenance are neglected. Experimental findings on cleansing, sterilization, and mechanical safety are discussed, leading to the conclusion that re-use of disposable catheters is possible only under certain circumstances.

Angiography↗
PubMed1986

[Splenomegaly].

Explore the source record for details and available documents.

Humans↗
PubMed1986

Detection of spontaneous echocardiographic contrast within the left atrium by transesophageal echocardiography: spontaneous echocardiographic contrast.

Transesophageal echocardiography was performed in 314 patients over a period of 24 months using a 3.5 MHz phased-array system fitted to the distal end of a conventional 12 mm endoscope. In 12 patients (2.6%) transesophageal echocardiography could not be performed because of adverse reaction to the gastroscopic procedure. Side effects were a transient A-V block in one patient and asthmatic attack in another. Mitral valve lesions were found in 99 of 314 patients. In 9 of these 99 patients (11%), including 1 patient with mitral valve stenosis and sinus rhythm, 2 with atrial fibrillation, 3 with disc, and 3 with porcine mitral prosthesis, spontaneous echocardiographic contrast was found within the left atrium, described as faint echoes in 2 patients and dense echoes filling the whole left atrium and following turbulent flow in the other 7 patients. Only in 2 patients was left atrium shown to have additional echoes within its cavity in the four-chamber view by transthoracic echocardiography. Signs of cerebral emboli were found in 5 of 9 patients and of peripheral embolism in 3 of 9 patients. Their mechanism seems to involve red cell aggregation, which is greatest at low flow velocity such as in dilated left atria in the case of mitral valve stenosis or prosthesis. The additional effect of platelet aggregation must be discussed because increased platelet aggregation was detected in all patients with spontaneous echocardiographic contrast. Transesophageal echocardiography seems to be of great diagnostic value in patients with mitral valve lesions and cerebral and peripheral embolism, giving new insight into the pathophysiologic mechanism and possibly improving the therapeutic approach in the near future.

Adult↗
PubMed1986

[Diagnosis and course of synovial sarcoma. Comparison of x-ray diagnosis and bone scintigraphy].

The unfavourable prognosis of malignant synoviomas makes it essential to arrive at an early diagnosis. The early clinical symptoms and radiological appearances may be minimal and sometimes absent. It is therefore advisable to obtain bone scintigrams with perfusion and early images as well as the radiographs. The local extent of the tumour can be evaluated by ultrasound and CT. Angiography is required only if the relationship to the vessels cannot otherwise be ascertained, or if intra-arterial therapy is being considered. The final diagnosis depends on a biopsy. For subsequent observation, both scintigrams and radiographs should be obtained. It is essential to perform a three-phase scintigram. This improves the recognition of recurrences and of soft tissue or bone metastases. Most bone metastases are visible on scintigraphy, but a normal scintigram in the presence of an osteolytic lesion on a radiograph may be obtained. Pulmonary metastases can only be demonstrated radiologically.

Adolescent↗
PubMed1986

[Selective blood sampling from the inferior petrosal sinus using digital subtraction angiography].

Simultaneous bilateral venous sampling of blood from the inferior petrosal sinuses helps in the differentiation between peripheral and central ACTH hypersecretion. One can also locate the site of a hormonally active hypophyseal micro-adenoma that cannot be demonstrated by other methods. The authors have experience with fifteen patients and discuss the indications, technique and problems as well as the advantages of using digital subtraction angiography.

Adenoma↗