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Biomedical subjects

F Fremuth

Publications and source records attributed to F Fremuth.

15 recordsLinked to original sources
PubMed1990

[Testing bronchogenic carcinoma cells for sensitivity to cytostatics in vitro and in cell cultures].

The authors submit the first experience assembled in Czechoslovakia with testing of the sensitivity of bronchogenic carcinoma cells to cytostatics by the HTCA method (Human Tumor Clonogenic Assay). Based on work by A. W. Hamburger, S. L. Salmon and others the authors elaborated their own modification of the method of cell cultivation in a double layer of soft agar, which can be used in small laboratories attached to clinical departments. The sensitivity tests were made in eight bronchogenic carcinomas--four adenocarcinomas and four epidermoid carcinomas. For the tests five cytostatics were used: 5-fluorouracil, methotrexate, cis-platinum, vincristine and vinblastine. Because of contamination the results in three tested adenocarcinomas could not be evaluated. The evaluated specimen of adenocarcinoma was sensitive to 5-fluorouracil and methotrexate, but was resistant to the remaining tested cytostatics. In the group of epidermoid carcinomas one specimen was completely resistant and one completely sensitive to all tested cytostatics. In one specimen the test with 5-fluorouracil could not be evaluated, and the specimen was resistant to the remaining cytostatics. The last specimen in this group was resistant to cis-platinum and sensitive to the remaining cytostatics.

Antineoplastic Agents↗
PubMed1984

Kinetics of growth inhibition in a neoplastic population after repeated cytostatic treatment.

The analysis of growth kinetics of a neoplastic population after cytostatic treatment (radiation, chemotherapy) has been modeled by means of the cell cycle transition probabilities mu and transition intensities lambda. The transition between phases of the cell cycle and quiescent G0 cells during repeated cytostatic treatment has been exposed by the probabilistic model on the basis of the experimental data. The cytostatic treatment (the most effective time, dose and therapeutic combination) can be scheduled using established size and volume of the tumor and an estimate of cell proportion in various compartments of the neoplastic population. The probabilistic model has been worked out with the object of repeated cytostatic treatments in the optimum time with respect to the reduction of resistant quiescent G0 population. By repeating treatment in these times, the G0 population may be effectively reduced, the tumor is loosing its proliferation (recovery) potential and the further tumor growth may be for a long time delayed or even ceased.

Animals↗
PubMed1982

Interactions between the growth effects of a kidney epithelial cell growth inhibitor and extracellular concentrations of cyclic nucleotides.

The effect of dibutyryl cyclic nucleotides, dbcAMP and dbcGMP, on the growth of BSC-1 cells has been studied in the presence and absence of kidney epithelial cell growth inhibitor. The growth response of the cells was dependent on concentrations of the dibutyryl cyclic nucleotides and on the presence or absence of serum in the medium. In the presence of serum, a high concentration (10(-3) M) of dbcGMP largely overcame the action of the kidney epithelial cell growth inhibitor. In the absence of serum, a high concentration (10(-3) M) of dbcAMP increased growth inhibition observed with the growth inhibitor. In the presence of serum, low concentrations of dbcAMP were growth stimulatory and partially overcame the action of the growth inhibitor.

Animals↗
PubMed1977

Changes in radiosensitivity induced by cyclic nucleotides and chemical radioprotection.

Cyclic AMP has a radioprotective effect and its aministration results in a significant increase in LD50/30 values in Chinese hamsters. The efficiency of these radioprotective effects is comparable to that of such radioprotective compounds as AET and cystamine + mexamine. Cyclic GMP is responsible for significant radiosensitizing effects. Changes in radiosensitivity after administration of cyclic nucleotides are both immediate and delayed and correlate closely with dose and time of administration.

5-Methoxytryptamine↗
PubMed1976

Repair synthesis of DNA after irradiation and its modification due to radioprotection in vivo.

Repair DNA synthesis was examined in bone marrow cells exposed to LD 50/30 in vivo. Intensive repair synthesis took place during the irradiation, and the increase in 3HTdR uptake prevailed over the inhibitory effect of radiation and AET upon DNA synthesis. After LD 50/30, the intensity of DNA repair was reduced. Application of AET resulted in an increase in repair DNA synthesis after irradiation, indicated by a significantly higher incorporation of 3HTdR.

Animals↗
PubMed1976

Proliferation kinetics and lethality after irradiation; modification by radioprotection.

By means of radioprotection, it was shown that a correlation exists after LD 50/30 between radiation-induced changes in cellular proliferation of critical radiosensitive tissue (bone marrow) and lethality, both in the time course and in the degree of the effect. Close correspondence between proliferation changes after irradiation and radiation lethality indicates that the inhibition of proliferation activity may play a major role in the mechanism of the death of irradiated organisms. A modification of cellular proliferation results in a change in radiation mortality. Pretreatment with the radioprotective compound AET leads to a moderation of both the inhibitory effect of radiation upon proliferation and radiation lethality.

Animals↗