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Biomedical subjects

H Zwicker

Publications and source records attributed to H Zwicker.

At least 37 records · Page 2Linked to original sources
PubMed1976

[Aortic abnormalities in Marfan's syndrome].

Three different forms of aortic lesions in Marfan's Syndrome are demonstrated: 1. moderately severe aortic valve insufficiency due to sinus of Valsalva aneurysm; 2. severe aortic valve insufficiency due to aneurysmal widening of the ascending aorta; 3. an unusually wide dissecting aneurysm extending from the aortic root to the aortic bifurcation. A review of the current literature of the changes in Marfan's Syndrome is given. It is obvious that early diagnosis of the cardiovascular changes is important for the patient's prognosis, allowing the optimal time for surgical intervention to be chosen.

Adult↗
PubMed1976

[The efficacy of cytostatic therapy for malignant tumors as determined by x-rays].

Cytostatic or hormone therapy for malignant tumors has made some progress during the last few years. Total or, at least, extensive recession of bronchial carcinoma, metastasizing breast tumors and lymphogranulomatosis in Stage IV as the result of chemotherapy or hormone therapy was presented which was substantiated by x-rays.

Adolescent↗
PubMed1976

[Consideration of inhomogeneities in irradiation planning. I. Influence of inhomogeneities on course of depth dose curve in water for cobalt60 gamma rays].

In radiation therapy, the focal doses during irradiation of a tumor are based on the values for water, since water has almost the same absorption coefficient as muscular tissue, even for different kinds and energies of radiation. But calculation of the tumor dose will become inaccurate if inhomogeneities in the ray path are not considered such as fat, bones, plaster, metal plates, Küntscher nail, endoprothesis. These materials, having a density phi different from water, represent inhomogeneities relative to water with regard to absorption of high-energy radiations. The experiments yielded the following results: All measurements revealed that the change in the course of the depth dose curve caused by inhomogeneities in water depends essentially on the density phi and on the thickness d of the inhomogeneity. If the density phi of the inhomogeneity exceeds one, a shift of the depth dose curve in water results in direction to the surface: if the density phi is smaller than one, the depth dose curve will move towards greater depth because of the inhomogeneity. With Co-60 gamma radiation, the shift of the depth dose curve in water due to an inhomogeneity occurs almost parallel. A correlation obtained empirically allows a calculation of the extent of the shift, the depth dose is subjected to, for different inhomogeneities. With the density of the inhomogeneity phi2 and the thickness d, the shift V in water (phi1=1) will result from V=0.5 (phi2-1) d (cm) in direction to the surface if phi2 greater than 1, towards greater depth, if phi2 less than 1.

Absorption↗
PubMed1975

The renogram and individual 131I-hippuran clearances in experimentally controlled renal perfusion.

The radioisotope renogram and renal clearances using 131I-Hippurate were studied during experimentally controlled renal perfusion. In the first series of experiments, renograms were recorded during variations in renal blood flow produced by an extracorporeal pump circuit. There was a close correlation between renal blood flow and renogram parameters. These characteristics were also related to urine flow rates. In the second series of experiments, unilateral renal damage was produced either by ischaemia or obstruction. Individual clearances using 131I-Hippurate and the gamma camera were compared with standard clearances obtained during a steady state. There was a close correlation between these methods and the results emphasise the importance of subtracting background radioactivity. It is concluded that the main value of the renogram is to provide a left to right comparison of renal tubular function whereas the value of corrected 131I-Hippuran clearances is to provide an absolute measure of individual effective renal plasma flow.

Animals↗