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R Felix

Publications and source records attributed to R Felix.

At least 829 records · Page 46Linked to original sources
PubMed1980

[Experimental investigations on the effect of etilefrinhydrochloride (Effortil) on heart and circulation of animals with partial ischaemic damage of the myocardium (author's transl)].

The effect of Etilefrin on the blood flow of normal and partial ischaemic myocardium with heat conductance probes as well as on the ventricular dynamics was investigated on 11 dogs under propiomazine-pentobarbital narcosis. Etilefrin was applied in doses of 0.04 mg/kg bw. and 0.2 mg/kg bw. At low doses, the blood flow was only elevated in normal myocardium, likewise the systolic aortic pressure, the diastolic aortic pressure decreased, the heart frequency was elevated, whereas the systolic pressure in the left ventricle was only slightly increased for a short time, the enddiastolic pressure unchanged, dp/dtmax rose significantly, but the heart minute volume only slightly. At higher doses, elevation of blood flow also appeared in partial ischaemic myocardium, the aortic pressure, systolic and diastolic, decreased considerably at first and then 20 min. p.i. rose to above the control value. The heart frequency was more elevated than at lower doses, the pressures in the left ventricle showed no obvious changes, dp/dtmax and heart minute volume were likewise considerably elevated. Radiological measurements of the ejection fraction and the mean circumferential fiber shortening velocity at higher Etilefrin doses showed also a positive inotropic effect. In consideration of this fact, therapy with Etilefrin appears useful in disturbances of cardiac function and at least shows no contraindication by means of myocardial blood flow.

Animals↗
PubMed1980

[CT and the heart: present state of the art and its future. A review (author's transl)].

Overview of non-invasive cardiac computed tomography (CCT) presently technologically feasible--with an outlook on the future. CCT seems to be an addition to the cardiodiagnostic imaging spectrum of cardiac isotope scanning and cardiosonography already firmly established; and it will probably soon have to establish its rank. The indications for CCT already proven and those awaited in the future will be systematically analyzed in this presentation. Conventional present-day CCT with long scanning times of 3-5 seconds has already provided satisfactory clinical information, considering the fact that there is slow motion of the damaged area in myocardial disease as experimentally shown by an over 20 min long arrest of contrast-material (given i.v.) in the infarcted areas. EKG-gated scanning and reconstruction techniques under development will provide better spatial and chronological resolution. However, much development is yet to be done, it is to be expected that CCT will eventually render data about the function of a specific area of the ventricular wall. Decreased scanning times and scanning intervals will provide dynamic studies of cardiac function and allow time/concentration examinations. These latter studies will be especially valuable to demonstrate the intracavitary cardiac flow in detail.

Cardiomegaly↗
PubMed1980

Fan-beam computerized tomography systems with rotating and with stationary detector arrays ('third' and 'fourth' generation).

Part I of the present work describes the fundamental problems important for understanding the function of fan-beam computerized tomography systems. First, the relationship between the number of detectors, the number of attenuation profiles, the number of volume elements in which the object slice is decomposed and the number of picture elements in the final image is explained. Then the influence of both the detector width and the sampling distance on the accuracy at which the attenuation profiles can be measured, is defined. Three spatial frequencies play an important part: the aperture cutoff frequency, the sampling frequency, and, coupled with the latter, the Nyquist frequency. Finally, the modulation transfer function, one of the most important quantitative characteristics of any computerized tomography system, is described. Part II of the present work describes the essential design characteristics of fan-beam computerized tomography systems with rotating as well as with stationary detector arrays. It is shown that both types of CT systems have been produced with different implementations. It is further explained that both CT types apply different sampling processes and, moreover, differ in image reconstruction techniques. However, it should be noted that this work presents only fundamental facts and does not attempt to be detailed.

Models, Theoretical↗
PubMed1979

Increase in alkaline phosphatase activity in calvaria cells cultured with diphosphonates.

1. Dichloromethanediphosphonate and to a lesser degree 1-hydroxyethane-1,1-diphosphonate, two compounds characterized by a P-C-P bond, increased the alkaline phosphatase activity of cultured rat calvaria cells up to 30 times in a dose-dependent fashion. 2. Both diphosphonates also slightly inhibited the protein synthesis in these cells. 3. Thymidine, an inhibitor of cell division, did not inhibit the induction of the enzyme, indicating that the increase in enzyme activity was not due to the formation of a specific population of cells with high alkaline phosphatase activity. 4. The effect on alkaline phosphatase was suppressed by the addition of cycloheximide, an inhibitor of protein synthesis. 5. After subculturing the stimulated cells in medium without diphosphonates, the enzyme activity fell almost to the control value. 6. Bovine parathyrin diminished the enzyme activity of the control cells and the cells treated with dichloromethanediphosphonate; however, at high concentration the effect of parathyrin was greater on the diphosphonate-treated cells than on the control cells. 7. The electrophoretic behaviour, heat inactivation, inhibition by bromotetramisole or by phenylalanine, and the Km value of the induced enzyme were identical with that of the control enzyme.

Alkaline Phosphatase↗
PubMed1979

Diphosphonates.

Explore the source record for details and available documents.

Animals↗
PubMed1979

[Coronary calcification and luminal diameter in coronary disease (author's transl)].

Two hundred and thirty-six patients with coronary heart disease were examined by coronary angiography and laevo-cardiography. In 111 patients (47%) there was coronary artery calcification. Of these, 108 patients (97%) showed abnormal findings on the coronary angiogram; in 72 patients (67%) coronary stenosis was greater than or equal to 50% of the lumen. The severity of the stenoses increased with the amount of calcification. There were only three false positive findings and the presence of coronary calcification indicates coronary sclerosis with a high degree of probability. Fluoroscopy is the simplest and most sensitive method of examination and is of great value in the non-invasive investigation of coronary sclerosis.

Calcinosis↗
PubMed1979

[Image characteristics of the computer tomograph (author's transl)].

In the present paper the images produced by spheres of varying diameter (d = 4,6,8,10 mm) embedded in a homogeneous substance of varying densities (H' = 3,48,93,137 Hounsfield units) as produced by computer tomography were studied. Measurements show that for each sphere diameter there is a minimum contrast between the substance of the sphere and its surroundings which must exist in order to show this sphere by computer tomography. It was also shown that the partial volume effect is of significance for the attenuation of the spheres. The effect of the position of the spheres within the slices to be imaged was studied. The results clearly indicate that in the investigation of small tissue changes in the body, the thickness of the slice and patient displacement should be kept as small as possible.

Absorptiometry, Photon↗
PubMed1979

[Image properties of computer tomography. III. Measurements on homogenous materials. Relationship of attenuation and scatter to various parameters (author's transl)].

The present paper investigates the variations due to various parameters on the image of homogeneous materials as obtained with the Somatom CT scanner. Sugar solutions were used with concentrations equivalent to the absorption values of soft tissues. Because of quantum noise, attentuation at various points is not uniform, but is distributed in a Gaussian manner round a mean value. Using the Evaluskop it was possible to determine the degree of scatter. It was shown that, with increasing density of the material, the scatter increased and that this can be reduced by subjecting the tomogram to a smoothing process. It was further shown how the scatter depends on various parameters, such as thickness and dose. The amount of scatter in a tomogram is important in determining the density gradation which can be a achieved.

Absorptiometry, Photon↗
PubMed1979

Preparation of factor VIII-deficient plasma by immunoadsorption.

An immunoadsorbent was prepared by coupling rabbit and human antibodies against human factor VIII to Sepharose CL-2B. The resulting insoluble antibodies completely removed factor VIII and fibrinogen from normal human citrate plasma. Other coagulation factors were satisfactorily recovered in the eluted plasma. Following addition of fibrinogen, the factor VIII-deficient plasma was used for calibration of the one-stage factor VIII assay and compared with the hemophilic plasma. Parallel straight lines were obtained in the log-log plot against VIII:C, indicating that the artificial reagent can be used as a substitute for hemophilic plasma in determination of factor VIII procoagulant activity. The immunoadsorbent can be regenerated and repeatedly used for affinity chromatography binding of factor VIII.

Animals↗
PubMed1979

[Diagnosis and differential diagnosis of cardiac enlargement in the chest film. Systematic survey (author's transl)].

The pathological enlarged heart is attempted to define by roentgenologic criteria. The historical "heart lung quotient" continues to be an important measurement. Alterations of the heart size secondary to age, the systolic-diastolic difference of the heart size and the alterations of the heart size between two chest films are discussed. Differential diagnosis of enlargement and shape of the left and right heart are presented. Also the differential diagnosis of general cardiac enlargement especially valvular heart disease, combined left and right heart failure, pericardial effusion and myocardiopathy is considered.

Aortic Valve Insufficiency↗
PubMed1979

[Extension of thoracic roentgen diagnosis by computer tomography (author's transl)].

In 400 examinations of the thorax results of computer tomography were compared with respective pa chest films and conbentional tomograms. In the peripheral areas of the lung, interstitial parenchymal alterations and metastases were better visualized by CT. The size of central bronchial carcinomas and space-occupying lesions of the thoracic wall can be determined with greater accuracy by CT. Primary tumors, lymphnode enlargement and vascular alterations can be differentiated and localized more precisely by CT. The size of the heart chambers, intracavitary tumors as well as septal and myocardial wall thickness can be determined non invasively.

Aortic Aneurysm↗
PubMed1978

The effects of diphosphonates on the growth and glycolysis of connective-tissue cells in culture.

1. The effects of two diphosphonates (compounds containing a P-C-P bond), disodium dichloromethanediphosphonate and disodium 1-hydroxyethane-1,1-diphosphonate, on the metabolism of cultured rat calvaria cells, rabbit ear cartilage cells and rat skin fibroblasts were investigated. 2. The diphosphonates had no effect on the growth of cartilage cells and on the exponential growth of the calvaria cells and the fibroblasts. However, dichloromethanediphosphonate stopped the growth of the calvaria cells and the fibroblasts after the beginning of confluence, whereas the untreated cells were still growing to a certain extent. This inhibition was dose-dependent. After the drug was withdrawn, the cells recovered slowly. 1-Hydroxyethane-1,1-diphosphonate had no detectable effect on the growth of any of the cell types studied. Both diphosphonates decreased the cloning efficiency of calvaria cells and fibroblasts. 3. The K+ content of cartilage, calvaria and skin cells was diminished only by the highest (0.25 mM) concentration of dichloromethanediphosphonate. 4. Radioactive dichloromethanediphosphonate and 1-hydroxyethane-1,1-diphosphonate were taken up linearly with time for at least 48 h by calvaria cells and fibroblasts. The diphosphonate concentration in the cells depended on its concentration in the medium. 5. Both diphosphonates, in a dose-dependent fashion, markedly inhibited glycolysis, dichloromethanediphosphonate being more effective than 1-hydroxyethane-1,1-diphosphonate, at drug doses that had no effect on cell growth or cellular K+ content. Calvaria cells were much more sensitive than cartilage cells. When cartilage cells were cultured in an N2 atmosphere, these effects on glucose and lactate metabolism disappeared. 6. As increased acid production appears to be associated with resorption of bone, this decrease in lactate may explain why diphosphonates are effective inhibitors of bone resorption in vivo.

Animals↗
PubMed1978

Stimulation of precipitation of calcium phosphate by matrix vesicles.

The ability of matrix vesicles isolated from the epiphysial growth plate of 6-week-old chicks to facilitate the precipitation of calcium phosphate was studied in vitro. The vesicles lowered the minimum concentration product [ca2+]X[p1] needed to induce crystal formation, thereby showing the vesicles are nucleators of crystallization. After freezing and thawing the vesicles at pH6.0, part but not all of this ability to nucleate disappeared. Freezing and thawing markedly decreased the Ca and Pi content of the vesicles, suggesting that part of the nucleating activity may have been due to mineral already present. After removal of the mineral the residual nucleating activity could be destroyed by extracting the vesicles with lipid solvents or by treatment with enzymes such as phosphoilipase C, neuraminidase or proteinase. Matrix vesicles obtained from chicks treated with 1-hydroxyethane-1, 1-diphosphonate, a compound that inhibits calcification in vivo, showed impaired nucleating activity, both before and after treatment at pH6.0. The vesicle preparation bound some diphosphonate in vitro, probably to the mineral present in the preparation, since no binding could be detected in vesicles preincubated at pH6.0. No difference was found in the nucleating activity of vesicles isolated from rachitic chicks which had or had not received cholacalciferol 48 h before death. These results suggest that matrix vesicles possess intrinsic nucleating activity that may be important in biological calcification.

Alkaline Phosphatase↗
PubMed1978

[Radiation exposure of the operator during angiography (author's transl)].

Radiation exposure to the forehead, hand, sternum and gonads of the operator was measured with a LiF dose meter during 134 angiocardiograms and 56 angiograms of the abdomen and the extremities. Average exposure during angiocardiography to the forehead was 3.2 mrem., to the hand 4.2 mrem. and the gonads and sternum about 0.5 mrem. per examination. During angiography of the abdomen and extremities, exposure was rather higher. The results of these measurements are compared with the findings of other authors and relate to dose-dependant somatic damage.

Angiocardiography↗
PubMed1978

[The diagnostic value of kymography in aortic isthmus stenosis (author's transl)].

The value of kymography was studied in 133 patients in whom a coarctation had been demonstrated angiographically, operatively or pathologically; its value was compared with conventional radiographic examinations. The difference in pulsation between the pib notching, dilatation of the ascending aorta and increased size of the left ventricle on plain films make it possible to diagnose an haemodynamically significant coarctation without any invasive methods. In 124 haemodynamically significant coarctations (93%), the kymogram showed increased pulsation of the dilated left subclavian artery. In nine haemodynamically insignificant or mild coarctations (7%), this sign was absent. Since the radiographic signs are to some extent reversible, it is possible to evaluate the results of surgery by plain chest films and the kymogram.

Adolescent↗
PubMed1978

[Quantitative functional analysis of the left ventricle in coronary heart disease. An evaluation of current methods. II. Correlation of results. Global and regional contractility parameters (author's transl)].

In the first part of the present paper, the basic methods for quantitative angiocardiography are described. In the second part, a variety of results are tabulated and discussed, derived from selective coronary arteriography, laevocardiography, left ventricular pressure measurements and heart size as seen on conventional chest X-rays. Various correlations have been derived from these. It was not possible to find an quantitative relationship between coronary sclerosis and myocardial function. The reason for this depends on the fact that the parameters derived from laevocardiography represent integrated global function. The significance of regional contractility is stressed.

Angiocardiography↗
PubMed1978

[Functional scintigraphy during contraction of the left ventricle. II. Evaluation of background correction (author's transl)].

During evaluation of cardiac function using 99mTc human serum albumen (functional scintigraphy during contraction of the left ventricle), it is necessary to take account of the background radiation which is derived from the lungs and great vessels overlying the heart. Only after correction of the background radiation is it possible to evaluate the severity of various types of cardiac insufficiency; this can be obtained by integrating the impulse during systole and subtracting this from the impulse rate over the left ventricle during a complete cardiac cycle. Apart from the background correction derived from the systolic-diastolic variation, it is necessary to obtain adequate resolution by examining 100 frames per second, an adequate picture matrix (4-K) in order to obtain adequate spacial resolution and accurate measurements of systole and diastole. The latter should be obtained not from the E.C.G., but directly from the volume curve of the left ventricle as determined by the isotope method.

Electrocardiography↗