Search PubMed⌕ Search

Biomedical subjects

R Felix

Publications and source records attributed to R Felix.

At least 631 records · Page 35Linked to original sources
PubMed1989

[Possibilities for imaging intracardiac thrombi with indium 111 thrombocyte scintigraphy].

Intracardiac thrombi can be localized and quantified by indium-111-labelling of thrombocytes with a high sensitivity and specificity. The scintigraphic procedure has a complementary evidence to echocardiography. Scintigraphy shows activity and age of thrombosis, whereas echocardiography seems to be superior in determination of mass and localization. In older thrombi scintigraphy fails because of organisation and endothelialization of the thrombus surface. For the reason of determination of the age of an intraventricular thrombus this method might have an increasing acceptance.

Aged↗
PubMed1989

How high is the true fibrinogen content of fibrinogen standards?

A number of tests are available to measure plasma fibrinogen. Of these, the determination of the thrombin induced rate of plasma clotting is the most widely used in a clinical laboratory. Quantitative fibrinogen assays are calibrated with commercially available standards. There exists no internationally recognized standard against which the manufacturers could calibrate their fibrinogen preparations and lyophilized normal plasmas. In the present study, the amount of clottable material was determined in ten commercially available fibrinogen standards. Following clotting with thrombin, the fibrin clots were extensively washed with citrated saline and subjected to nitrogen analysis. The proportions of intact and partially degraded fibrinogens in each standard were determined by SDS-polyacrylamide gel electrophoresis of the washed clots. Knowing the amino acid composition and the relative proportions of these fractions, the nitrogen contents of the clots were converted to fibrinogen. More than 30% deviation from the declared values was observed in three standards, in one of them even 80%. Our results indicate that fibrinogen standards of markedly differing quality are commercially available and that an accurate, international standard for fibrinogen assay should be established.

Blood Coagulation↗
PubMed1989

[Hemostasis parameters in 55 patients with venous and/or arterial thromboembolisms].

55 consecutive patients (28 males and 27 females) who had suffered from (recurrent) venous and/or arterial thromboembolism were evaluated for laboratory findings of thrombophilia. At the time of investigation, 15 patients were taking oral anticoagulants. In addition to patient and family history and clinical examination, a coagulation profile, euglobulin clot lysis time before and after venous occlusion, assays of plasminogen, antithrombin III, protein C (PC), free protein S (PS[f]), and C4b binding protein bound protein S (PS[b]) were obtained. 2 patients not orally anticoagulated had partial PD deficiency with functional PC activity values of 53% and 57% respectively, as compared to normal human plasma (NHP). Functionally active PS(f) was found to be lower than normal in 14 patients not taking oral anticoagulants and without signs of hepatopathy. In 4 of these 14 patients partial PS deficiency was present (PS[f] between 7 and 37% of NHP, and PS[b] between 51 and 86% of NHP). In one of these 4 subjects the hereditary nature of PS deficiency was proven by investigation of family members. In 3 of the 14 patients a shift from PS(f) (between 34 and 66%) towards PS(b) (124-141%) was found. The remaining 7 patients showed subnormal PS(f) values (56-64%) and normal PS(b) values (78-105%). In the patients receiving oral anticoagulant therapy, PC and PS levels were diminished. Statistically there was no close relationship between PC and PS levels on the one hand and prothrombin time values on the other. In anticoagulated patients, therefore, PC or PS deficiency can only be diagnosed by investigation of members of the propositus's family.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Radioimmunoscintigraphy of ovarian cancer with 131-iodine labeled OC-125 antibody fragments.

Radioimmunoscintigraphy (RIS) with 131I labeled OC-125 F(ab')2 monoclonal antibody fragments was prospectively studied in 43 women for primary diagnosis and follow up of ovarian cancer. Total body planar photoscans with a scintillation camera were performed one to seven days after antibody application and results were compared with operation and or CT examination. By the region of interest technique the tumor to non tumor tissue ratio (T/N) was calculated in vivo. Sensitivity in primary diagnosis was 100% (10/10), specificity 33% (1/3). For local recurrency, sensitivity was 86% (19/22), for metastatic loci 80% (17/21). Specificity was 75% and 50%. T/N ratio was in the rage from 1.3 to 2.8. Sensitivity for ovarian cancer is high in primary diagnosis and follow up. By the region of interest technique it is possible to detect small recurrencies and to presume peritoneal carcinosis. Antibody accumulations in diseases different from ovarian cancer however diminish specificity.

Adult↗
PubMed1989

Comparison of multi echo and contrast-enhanced MR scans: image contrast and delineation of intracranial tumors.

In 56 patients with intracranial tumor T2-weighted multi echo (ME) [TR: 1600 ms, TE: 30 to 240 ms (8 echoes)] and T1-weighted Gd-DTPA-enhanced images (TR: 400 ms, TE: 30 ms or 35 ms) were compared with respect to tumor contrast and tumor delineation. In subgroups of 20 and 14 patients, respectively, tumor/brain- and tumor/edema-contrast were assessed on both a subjective and a quantitative basis (contrast-to-noise ratio, CNR). CNR's for tumor/brain-contrast were significantly higher on Gd-DTPA enhanced images than on ME scans. No significant differences between techniques were found for CNR's of tumor/edema-contrast. ME images yielded pathological findings in 54 of the 56 patients but visually assessed tumor delineation was achieved in only 36 cases. Fifteen out of 25 intraaxial tumors and 5 out of 31 extraaxial tumors could not be sufficiently delineated on ME images. In contrast, Gd-DTPA-enhanced images provided differentiation of tumor and surrounding tissues in 55 of 56 studies. In conclusion, ME images have proved highly sensitive in detecting intracranial lesions. However, brain tumors, especially intraaxial tumors could often not be differentiated from adjacent tissues on ME images. After Gd-DTPA, T1-weighted images provided more reliable tumor detection and delineation.)

Adolescent↗
PubMed1989

[Postoperative results and follow-up of thoracic aortic diseases using magnetic resonance tomography].

Operations of the thoracic aorta for aneurysms, dissections, or congenital malformations may lead to early or late complications. Therefore, postoperative control for documentation of the surgical results, for exclusion of early changes and for comparison with later controls is mandatory. To demonstrate that magnetic resonance imaging (MRI), which we already had used with good results for preoperative studies is also able to detect postoperative abnormalities, we examined 30 patients with thoracic aortic disease (20 male, 10 female, mean age 53 +/- 13.7 years) with this diagnostic tool. There were 19 arteriosclerotic aneurysms, 10 dissections, and one aortic tumor. With MRI it was possible in all patients to visualize the results of the surgical treatment postoperatively. Early postoperative complications could be excluded, or demonstrated in one case of a retrograde aortic dissection or a hematopericardium. These pathological findings could also be shown by arterial digital subtraction angiography or echocardiography. Using MRI for follow-up of aortic dissections, the development of an aneurysm of the aortic root in a Marfan-patient could be detected. In all these patients, it was possible to differentiate true and false lumen and to detect the origin of major side branches. The diagnostic advantages of MRI, which we compared with other imaging methods, as echocardiography, computed tomography or angiography are that postoperative complications of thoracic aortic aneurysm surgery can be reliably detected and visualized in 3 different planes. Non-invasiveness, the omission of ionizing radiation and no risk of contrast media application underline that magnetical resonance imaging is an ideal method for follow-up after operation of the thoracic aorta.

Aortic Dissection↗
PubMed1989

Imaging of acute myocardial infarction by magnetic resonance tomography (MRT) using the paramagnetic relaxation substance gadolinium-DTPA.

Twenty-six patients admitted to the Free University of Berlin University Hospital catheterization laboratory with acute myocardial infarction were studied. The diagnosis was confirmed by angiography, but acute revascularization was unsuccessful in every case. MR imaging was performed within 7 days of the acute event in 11 patients with uncomplicated clinical courses after acute infarction. Imaging was performed within 3 weeks in three additional cases, while the remaining 12 patients underwent studies more than 3 weeks after infarction. We determined signal intensity at three points within the area of infarction and at three other points in adjacent myocardial tissue. Decreased signal intensity within the area of infarction was found in native scans in 60% of all cases. Administration of gadolinium-DTPA 0.1 mmol/kg body weight was followed by a mean 70% increase in signal intensity within the zones of acute infarction, as compared to a 20% increase in surrounding myocardial tissue. In cases of subacute and chronic infarction, there was no significant signal enhancement after administration of gadolinium-DTPA. Uptake of the substance in the area of acute infarction may be a positive marker of acute myocardial necrosis and as such may prove useful in the clinical setting.

Acute Disease↗
PubMed1989

Bone-resorbing cytokines enhance release of macrophage colony-stimulating activity by the osteoblastic cell MC3T3-E1.

It has been observed that bone resorption in response to interleukin 1 (IL 1) or tumor necrosis factor (TNF) is accompanied by an increase in osteoclast number. Because the osteoclast is of hemopoietic lineage, recruitment could be regulated by colony-stimulating factors, one of which may be macrophage colony-stimulating factor (M-CSF). In this study, we show that the constitutive release of M-CSF activity by the osteoblastic cell MC3T3-E1 is enhanced by the presence of recombinant IL 1 alpha, recombinant TNF alpha, or by the concurrent presence of purified transforming growth factor beta (TGF beta) and epidermal growth factor (EGF). Increased release of CSF by the osteoblast in response to these agents may provide a signal for the growth and maturation of osteoclast precursors leading to subsequent bone resorption.

Animals↗
PubMed1989

[Dynamic MR tomography of intrahepatic tumors].

By combining rapid imaging and bolus injections of the paramagnetic contrast medium gadolinium-DTPA, it is possible to perform dynamic MR imaging. The diagnostic value of dynamic MR imaging was investigated in 28 patients with focal liver lesions. Malignant tumours appear hypo-intense during the early phase of the dynamic study and are better distinguished from normal liver tissue. Haemangiomas produce a typical 'fill-in phenomenon' after contrast application and achieve very high signal intensity. Focal nodular hyperplasia is characterised by very rapid signal enhancement within the first minute after contrast injection. Dynamic MR imaging represents further improvement in the MR differentiation of liver tumours.

Adult↗
PubMed1989

[Digital image intensifier radiography--application in angiography, urography and bone diagnosis].

In a retrospective study, the clinical usefulness of digital image intensifier radiography was analysed. It could be demonstrated that for angiographic procedures the image quality of a 1024(2) matrix is superior to a 512(2) matrix. For digital excretory urography it could be seen that in 80 to 90% the images were at least sufficient to analyse the renal pelvis. Digital image intensifier radiography of bones was diagnostically sufficient in 76% and analysis of bone architecture was possible in 85%.

Angiography↗
PubMed1989

[Psychomotor epilepsy--a comparison of CT and MR in 100 patients].

The value of CT and MR was studied in 100 patients with temporal lobe epilepsy. Axial CT scans were obtained before and after contrast injection. Coronary MR scans were carried out with T1-(SE 400/30, GE 315/14) and T2-weighted sequences (SE 1600/30 + 70). A circumscribed lesion was demonstrated in fifteen patients by CT and in 25 patients by MR. With the exception of a small area of calcification, all lesions seen on CT could also be recognized on MR. In four patients CT, MR and pathologic specimen could be compared following partial resection of temporal lobe. Localized glial reactions, which were not seen on CT, produced a signal difference on MR. Better sensitivity and improved demonstration of the temporal lobes makes MR the method of choice in the diagnosis of temporal lobe epilepsy.

Adolescent↗
PubMed1989

[Subacute cerebral infarct: native and contrast medium-enhanced MRT].

Twenty-five patients with clinical and CT findings indicating supratentorial cerebral infarct were prospectively studied with MR. MR examinations were performed between the 3rd and 150th day after stroke. T2-weighted axial images were compared with T1-weighted sequences after i.v. administration of Gd-DTPA. T2-weighted images demonstrated parenchymal lesions in all 25 patients. Postcontrast T1-weighted images, however, displayed pathologic contrast enhancement in only 19 areas of infarction. In 5 of the 25 patients, the use of Gd-DTPA provided additional diagnostic information by demonstrating gyral contrast enhancement as a pattern typical for ischemia. In 2 of the 25 patients, pathologic contrast enhancement was observed in an area that was isointense to the surrounding brain tissue on the T2-weighted images. In one patient, Gd-DTPA improved differentiation between areas of subacute and chronic infarction. At present, in the patient with suspected cerebral infarction, MR imaging after i.v. administration of Gd-DTPA appears recommended when clinical findings and CT are equivocal.

Acute Disease↗
PubMed1989

[Malignant chest wall infiltration in MR: comparison with CT and surgical findings].

CT and MRI were performed on 19 patients with pleura related thoracic tumors with respect to the detection of chest-wall invasion. All patients underwent surgery, which confirmed malignant infiltration in 16 cases, while this was excluded in three. CT showed chest-wall invasion in 12/19 patients. MRI demonstrated tumorous involvement in 16 patients. A reliable pattern of chest-wall invasion in MRI were high signal intensity lesions within the chest-wall in the T2-weighted images. However, increased signal intensity of pleural structures was found in inflammatory as well as in malignant lesions. MRI can prove the presence of chest-wall invasion when CT is equivocal.

Adult↗
PubMed1989

[MRT in primary and tumor-induced syringomyelia].

The MRI findings in 26 patients with primary syringomyelia and eight patients with a syrinx due to an intramedullary tumour were studied retrospectively. In general, the syrinx in the tumour cases resembled the appearance of primary syringomyelia. However, a specific and sensitive sign of tumour-induced syringomyelia was irregularity of the spinal cord close to the tumour (eight cases of eight), eccentric position of the lumen (seven of eight), and a diffuse increase of signal intensity on T2-weighted images (eight of eight). Primary syringomyelia also showed increased signal intensity on T2-weighted images outside the lumen, but this was closely related to the cavity. The use of Gd-DTPA improved demarcation of the tumour from the syrinx in all cases. Widening of the spinal canal and ectopia of cerebellar tonsils was a typical finding in primary syringomyelia. MRI proved a reliable method for distinguishing between a tumour-induced syrinx and primary syringomyelia.

Adolescent↗
PubMed1989

Regression of left ventricular hypertrophy under ramipril treatment investigated by nuclear magnetic resonance imaging.

Thirty-two hypertensive subjects with diastolic blood pressure greater than 95 mm Hg were treated with ramipril over a period of 3 months. To determine the effective decrease of blood pressure and for reliable and reproducible demonstration of regression of myocardial hypertrophy during ramipril treatment, we performed parallel measurements with magnetic resonance imaging (MRI) and echocardiography. Measurements were carried out before treatment, 4 h after the first dose, and after 14 days and 3 months of treatment. MRI slices showed a significant decrease of interventricular septal thickness from 19.57 to 15.20 mm, whereas echocardiography demonstrated an equivalent decrease from 18.78 to 14.57 mm. At each measuring point, quantification of wall thickness was performed three times and the means were calculated. The septum and the posterior wall of the left ventricle were also measured at three different points. The values were obtained with negligible scatter and the changes with ramipril treatment were highly significant (p less than 0.001). A concomitant decrease of blood pressure was also observed. The therapeutic aim to reduce diastolic blood pressures below 90 mm Hg was achieved in all patients. In addition to the significant reduction in blood pressure, the angiotensin converting enzyme (ACE) inhibitor ramipril caused a significant regression of pathologic left ventricular hypertrophy demonstrated by magnetic resonance imaging and echocardiography.

Adult↗
PubMed1989

Graves ophthalmopathy: MR imaging of the orbits.

Thirty-nine patients with Graves ophthalmopathy were examined with magnetic resonance (MR) imaging at 0.5 T with use of a surface coil. T1- and T2-weighted spin-echo images were obtained, and T2 relaxation times of eye muscles and retrobulbar fat were calculated from a multiecho sequence. Normal values for T2 relaxation times of eye muscle were obtained by examining nine control subjects. MR imaging demonstrated eye muscle enlargement in 23 patients. Visual examination of T2-weighted and calculated T2 images showed areas of high signal intensity in enlarged eye muscles of 12 of 23 patients. Calculated T2 relaxation times of eye muscles differed significantly between control subjects and patients with stage III and IV disease. Signal intensity characteristics of these changes, as well as their correlation with well-known histologic findings, suggested their interpretation as edema caused by acute inflammation. Since computed tomography is not able to depict eye muscle edema, the MR findings of structural changes within enlarged eye muscles might have an impact on therapeutic decisions concerning the application of anti-inflammatory drugs.

Adult↗
PubMed1989

[EEG and SPECT in cerebral manifestations of AIDS].

The purpose of the presented study was to determine the diagnostic value of correlated EEG and SPECT findings in patients with CNS-manifestations of AIDS. Ten HIV 1 infected patients had been examined. Diagnoses: meningitis (2 x), lymphoma (2 x), necrotizing encephalitis (1 x), toxoplasmosis (7 x) (Some patients had more than one diagnosis). Unenhanced and Gd-DTPA enhanced MR, 99mTc-HM-PAO SPECT and clinical EEG were compared. In 9/10 patients MR demonstrated intracranial lesions. In one patient with necrotizing encephalitis (not detected by MR), SPECT revealed an inhomogeneous cerebral perfusion. Only lymphoma was hyperperfused. Toxoplasmic lesions-when detectable by SPECT-were hypoperfused. Reduced rCBF was also seen in brain regions not affected directly, but functionally associated to altered areas. EEG revealed diffuse signs such as slowing in patients with brain atrophy, but also in those patients with lesions of basal ganglia and thalamus. Focal signs in the EEG were in concordance with imaging findings in only 2/10 patients. In 4/10 patients foci even adjacent to the cortex - as shown by MR - remained undetected by EEG. One patient with an active toxoplasmosis had sharp waves over the affected region. The parallel application of the three methods as suggested in this paper appears useful not only for scientific purposes. In most cases, this procedure provides relevant diagnostic information. It is recommended for AIDS-patients with CNS manifestations of unknown etiology.

Acquired Immunodeficiency Syndrome↗