Biomedical subjects
Publications and source records attributed to H Guski.
Biopsies of rectum carcinomas from 17 patients have been investigated by means of lights microscopical morphometric methods before and in the course of x-radiation therapy. According to the morphometric results, a x-ray dose of 2 000 rd is considered as being efficient, and 4 000 rad as an optimum dose.
The possibility of using modified formulas for determining the surface density of cellular membranes of the heart muscle cell was discussed, sarcoplasmic reticulum and particularly mitochondrial cristae being used as examples. By using modified formulas and different stages of magnification it could be possible to determine the surface density of critae also in such experimental conditions in which the mitochondrial cristae appear to be densely packed.
Comparative ultrastructural morphometric and physiological examinations of the rat's myocardium after swimming exercise, hypokinesia and hypobaric hypoxia show concurrence between morphometric and contractility parameters. Differences in the changes of cell organelles in general and of mitochondria and sarcoplasmic reticulum in particular observed in the experimental models of adaptation used provide a basis for making inferences as to different structural reaction patterns of the myocardial cell. Special importance is attached from the functional point of view to changes in the volume and membrane surface density of the longitudinal sarcoplasmic reticulum and in Golgi's apparatus. Different structural reaction patterns suggest different adaptation mechanisms of the myocardial cell.
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The authors describe device and functioning of a new efficacious membrane thin-layer oxygenator, specially developed for experiments on the isolated hearts of small animals. Compared with customary oxygenators with direct oxygenation, advantages arise from the separation of gas and perfusion solution, and its small volume for filling (7,5 ml). The diffusion capacity of the oxygenator (exchange surface 980 cm2) was tried by means of a hemoglobin-free modified Krebs-Henseleit solution with various flow values at 37 degrees C, depending on the gage of the layer. At the optimal gage of 0,15 mm and a flow value of 15 ml/minute a perfusion solution can be oxygenated from 0 to 570 torr, and an airequilibrated solution up to 646 torr. Measurements of oxygen consumption in the isolated perfused rat heart proved that the diffusion capacity of the membrane thin-layer oxygenator will suffice the oxygenation of the coronary minute volume of the arrested heart according to Langendorff as well as of the working heart according to Morgan. Primarily this oxygenator is useful for experimental organ perfusion in metabolic and functional tests, and organ preservation. Its functioning principles, however, also permit its use as thins-layer dialysator.
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A method is described for producing a localized coronary artery stenosis by tieing two threads around the Ramus descendens of the left coronary artery, which produces progressive cell proliferation of the vascular wall. Studies on 102 male Wistar rats (70 experimental and 32 sham-operated control animals) have shown coronary artery stenosis narrowing the lumen by more than 50% (up to and exceeding 90%) to develop after 7 days in 30% of the animals, after 14 days in 75%, and after 21 days (postoperatively) in 100%. In about one-third of the cases subtotal infarction in the supply area of the left coronary artery occured as a result of post-operative damage to the coronary artery with obturating thrombosis. The induction of effective coronary stenosis limiting the coronary reserve offers possibilities for further experimental studies on the role of relative coronary insufficiency in the pathogenesis of myocardial infarction.
A stenosing proliferation of the vascular wall was produced by exposing the Ramus descendens of the rat's left coronary artery to continued mechanical stimulation. Two weeks after the operation the hearts were perfused according to a modified Langendorff method, and the flow rate was measured under aerobic conditions and following short-time anoxia. Under either experimental conditions, the flow rate proved to be significantly decreased.
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