Biomedical subjects
Publications and source records attributed to G Fekete.
A useful technique for the investigation of skeletal fractures is the application of 99mTc phosphon isotope. This method may complete the X-rays and physical examinations, and it is especially useful in cases, when the date of vertebral compression is unknown.
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Sister chromatid exchange studies were conducted in 53 children with malignant diseases. Children with acute lymphoid leukemia in long remission, already off chemotherapy or on maintenance therapy, had normal SCE values, whereas those receiving intensive cytostatic therapy showed elevated levels. SCE values were primarily related to the time and dose of preceding cytostatic drug therapy, and the subsequent relapse might influence the SCE frequencies, independently from the cytostatic therapy.
The present study was undertaken to assess the relationship between the mechanical power developed during new anaerobic power test and muscular fiber distribution. Ten track and field male athletes were used as subjects, whose muscle fiber composition (m. vastus lateralis) varied from 25 to 58 fast twitch (FT) fibers. The test consisted of measuring the flight time with a special timer during 60 s continuous jumping. A formula was derived to allow the calculation of mechanical power during a certain period of time (e.g., in the present study every 15 s during 60 s of jumping performance). The relationship between the mechanical power for the first 15 s period correlated best with fast twitch (FT) fiber distribution (r = 0.86, p less than 0.005). However, the power output during the successive 15 s periods demonstrated lower correlation with FT, and this relationship became statistically non-significant after 30 s of work. The sensitivity to fatigue of the test was supported by the relationship observed between the decrease of power during 60 s jumping performance and the percentage of FT fibers (r = 0.73, p less than 0.01). Thus, the present findings suggest that muscular performance, as determined by the new jumping test, is influenced by skeletal muscle fiber composition. The new test, which primarily evaluates maximal short term muscular power, also proved sensitive in assessing fatigue patterns during 60 s of strenuous work.
Novel synthetic glucocorticoid analogues were tested for receptor binding and glucocorticoid activity. They were of unusual structure, insofar as they had a 3-chloro rather than a 3-oxo function. 3-Chloro analogues of fluorinated glucocorticoids formed extremely stable complexes with the rat liver glucocorticoid receptor. 3-Chloro derivative of fluocinolone acetonide also had in vivo glucocorticoid activity. It induced tyrosine aminotransferase in the liver and repressed thymidine kinase in the thymus very effectively. It is concluded that 3-chloro analogues may retain glucocorticoid activity as well as the ability to bind to the glucocorticoid receptor protein.
Between 1971 and 1981 756 children were diagnosed to have leukaemia in Hungary. Of these, 17 had Down's syndrome. Analyzing the clinical course of their leukaemia revealed a low remission rate and very poor survival in these patients. Down's syndrome seems to present a special high-risk feature, for early death or relapse into leukaemia, which is only partially explained by the accompanying abnormalities.
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To investigate the influence of skeletal muscle fiber composition on the mechanical characteristics of human skeletal muscle under isometric and dynamic conditions, ten well-trained track athletes with different muscle compositions (m. vastus lateralis) were used. The subjects were instructed to perform maximum isometric and dynamic knee extensions at maximal speed against increasing load. To determine the mechanical properties of the knee extensors a special dynamometer was used. The load was increased by adding weight discs to the electromagnetic part of the dynamometer. The load increased from 0.33-2.33 kg2 moment of inertia in six stages. The data were handled on the basis of Hill's characteristic equation. The subjects were divided into two equal groups, one with more and one with less than 50% of fast twitch fibers. The force-velocity curve was found to be different in the two groups, the subjects with a predominance of fast twitch fibers being able to develop higher power output at a given load. Significant correlations between percentage of fast twitch fiber and power, as well as velocity, were found at the four greater loads only. However, when the percentage of fast twitch fiber and fast twitch fiber cross-sectional areas were combined, significant correlations were also found between this combined parameter and power output at the two lowest loads.
Lymphocyte responsiveness to phytohaemagglutinin and viral antigens was studied in children with Down's syndrome and in controls. Mitogen-responsiveness in the patients was significantly reduced as compared to the control values. Using the lymphocyte transformation test, trisomic patients showed more than a twofold increase in sensitivity to herpes simplex virus as compared to controls. The same test did not show any essential difference between the two groups when adeno- and influenza viruses were used. Immunofluorescence technique, with specifically conjugated antiviral sera, permitted the detection of specific fluorescence in 30% of the patients with Down's syndrome indicating the presence of oncogenic adenovirus type 12 antigen in the circulating lymphocytes. No antibodies--or only very low titres--against adeno- and herpes simplex viruses were demonstrated in the sera of trisomic patients. Mononuclear leukocytes from these patients often showed structural alterations. The incidence of infectious herpes simplex virus and Candida albicans in the saliva of patients was higher than in the control group. It seems that Down's syndrome involves partial disturbance of both the cellular and humoral immune functions--at least with respect to certain viral antigens.
Stretch-shortening cycle refers to the mechanical condition in which store and recoil of elastic energy occur in the skeletal muscle. This leads to a greater work output when compared to a simple shortening contraction. The subjects performed vertical jumps with and without preliminary counter-movement and with small and large knee angular displacement. The results indicated that those subjects who had more fast twitch (FT) fibers benefited more from the stretching phase performed with high speed and short angular displacement. The amounts of elastic energy stored in this phase were 30 and 26 N X kgBW-1, respectively, for FT and slow twitch (ST) type subjects. The recoil of elastic energy was proportional to the amount of energy storage. In large amplitude jumps where transient period between stretch and shortening is long the both types of subjects demonstrated similar amount of storage of elastic energy (17 and 16 N X kgBW-1, respectively). However, the re-use of this elastic energy was greater in ST group (24%) as compared to the FT group (17%). The results can be interpreted through differences in sarcomere crossbridge life times between fast and slow muscle fibers. The slow type muscle may be able to retain the cross-bridge attachment for a longer period of time and therefore it may utilize elastic energy better in a slow type ballistic motion.
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A high proportion of the "intermediate" muscle fibres, which are semi-dark after both acidic and alkaline preincubation in ATP-ase staining, was found in the thigh with heart failure. Characteristic patterns of fibre splitting were found mostly in jumpers' muscles. Possibilities of fibre subgroup transformation and fibre hyperplasia due to training are discussed.
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5 year follow up assessment of 224 malleolar fractures showed that the prognosis was significantly worse if they were associated with fractures of the anterior or posterior tibial rim. In cases without tibial rim fractures severe late x-ray and clinical changes were found only below 4%, while with small marginal fragments they were below 20% and with greater fragments above 30%. Chances are worse in tibial rim fractures even with no or minimal involvement of the joint surface. This is explained by the fact that forces causing fracture-dislocation are more detrimental for the joint surface in the sagittal than in the lateral plane.
Aerobic efficiency characterized by the amount of oxygen consumed, per kg of b.w. and per meter of distance while running at a steady pace of 12 km/h (in children 10 km/h) attained 0.18--0.21 in trained athletes over 16 years of age and 0.23--0.25 in children. Trained children had only marginally better efficiency than the untrained schoolchildren, and there was no significant difference among values found in the athletes, which can be explained by their experience in running. The larger was the fibre area in the thigh muscle of sprinters, the worse was the aerobic efficiency, while in long distance runners there was no correlation between these two parameters. Taking the error VO2 measurements into account, it is rather doubtful that "routine" determination of aerobic efficiency has any diagnostic value.
The chromosome mutations and the number of sister chromatid exchanges induced by different kinds of immunosuppressive treatment were investigated in children and adults with certain types of renal diseases. The aim of the study was to find among the treatment schedules those promising good therapeutic results with the least mutagenic effects. A slightly decreased chromosome stability was found in the patients treated by cyclophosphamide therapy.