Biomedical subjects
Publications and source records attributed to A N Dedenkov.
Investigations carried out in various transplantable tumours (Lewis carcinoma, carcinoma-37, melanoma B-16 in mice and sarcoma-45 in rats) did not show 125J-triiodothyronine accumulation by the tumour.
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A comparative analysis of triiodothyronine (T3) and thyroxine (T4) distribution in organs and tissues of tumour-bearing and intact mice conducted wih 125J labelled T3 and T4 has shown considerable differences in the accumulation character of these hormones in mice with Lewis carcinoma and in intact animals in the liver, kidneys, lungs, adrenal glands, lymphatic nodes. Low T3 and T4 concentration in the blood of tumour-bearing mice was observed during the whole period of study.
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When DNA and the rubomycin-DNA complex were incorporated into liposomes containing stearylamine, about 90 per cent of their amounts associated with the liposomes, incubation of such liposomes for an hour at 25-50 degrees C being not accompanied by liberation of DNA and its complex. Only about 10 per cent of DNA associated with the liposomes was destroyed by DNase I. The liposomal DNA was more stable to ultrasound than free DNA. The molecular mass of DNA associated with the liposomes on treatment with ultrasound decreased 1.9 times, whereas that of free DNA decreased by more than 3 times. With an increase in the weight ratio of lipid/DNA the level of DNA degradation lowered. This is evidence of the fact that liposomes increase resistance of DNA and its complex to chemical and physical factors.
A simple procedure for preparation of tritiated anthracycline antibiotics, such as rubomycin and carminomycin is described. The method is based on isotope exchange with tritiated water at 100 degrees C. The specific activity of the preparations is several hundreds decays a minute per 1 microgram. The stability of the antibiotic label in aqueous solutions at various pH values was determined. At pH 7.2 and a temperature of 37 degrees C the loss of the tritium by the end of the 1st, 2nd, 3rd, 4th and 7th day amounted to 7.1, 11, 14, 19, and 24 per cent, respectively. It is concluded tht tritiated antibiotics prepared with the method of tritiated water exchange may be used in biomedical investigations.
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The use of the DNA-rubomycin complex resulted in appearance of one-thread breaks (OB) in DNA and markedly increased the number of the DNA OB determined immediately after irradiation. The DNA-rubomycin complex decreased the volume of the repaired OB and induced postreparation degradation of the one-bond DNA (oDNA) in the sarcoma 180 cells. The effect of the decrease in the molecular mass of the oDNA 6 hours after the irradiation to the level of the initial damage is probably in favour of the fact that degradation takes place in the areas of the repaired breaks. The data indicated that the viscosimetric method for the analysis of the OB in DNA may be promising in estimation of the efficacy of radiation and chemotherapy of solid tumors.
Studies performed on mice transplanted sarcoma 180 subcutaneously indicated that the UHF-field of non-thermogenic intensity in multiple (5-10 fold) total irradiation inhibits the tumor growth (T = 60%) and produces a 1.5 times increase of an average survival in tumor-bearing animals. It is suggested that there is a direct relationship between the increased antiblastic function of the body and a stimulating effect of the UHF-field on the immune response in animals.
It was found that combined treatment of sarcoma 180 with local U. H. F.-hyperthermia and carminomycin resulted in the tumor growth inhibition by more than 90 per cent, which was much higher than the effect of every agent alone. The thermochemotherapy allowed a decrease in the dose of the antibiotic without decreasing the antitumor effect. The U. H. F.-hyperthermia has an independent tumorolytic effect and promotes selective accumulation of carminomycin by the tumor.
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The experiments on male mice of SVA line showed that irradiation in the UHF-field 48 hours after the animal immunization with sheep erythrocytes increased the number of the antibody-producing cells in the spleen at least 3 times. On the background of immunodepression induced by rubomycin the UHF-field increased the primary immune response 2.5 times and the number of cariocytes in the spleen 1.8 times as compared to the control.