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Biomedical subjects

L Novák

Publications and source records attributed to L Novák.

At least 73 records · Page 4Linked to original sources
PubMed1977

[A new method for the determination of tissue sensitivity to dental materials in cell cultures].

This paper discribes a method that enables a qualitative analysis of the biological effects of stomatological materials upon living cells cultivated in vitro to be made. This method allows to make photographic records, at regular intervals of time, of those cells which are originally in a state of suspension, then start to adhere to the bottom of the vessel used for purposes of cultivation, when they become flat and wider. This method takes of the capability of cytoplasmic membranes to respond to any kind of chemical or physical noxa. Quick-motion pictures taken at regular intervals of time using ciné film provide for a quantitative differentiation and determination of the ratio of dilated to nondilated cells, which can be analyzed statistically.

Biological Assay↗
PubMed1977

[Methods for the biological testing of dental materials on cell cultures].

This paper discusses some of the methods used by for making basic biological tests of stomatological materials. Although we do not dispense with the use of methods based upon the observation of fixed and, possibly, stained cells and allowing the states assumed by cells in a certain period of time to be noted, yet we believe that far better results may be obtained from tests enabling the development of changes of living cells cultivated in vitro to be followed. The results of the experiments conducted by the authors indicate that it is possible for the final effect to be modified in dependence upon the type of material used, its concentration, or the time allowed to elapse from the preparation of the particular material and that an observation of living cells procides much more information about the character of alterations and, more specifically about the time course of changes. If necessary, this method may be supplemented by an electronmicroscopical analysis of the changes produced.

Cells, Cultured↗
PubMed1975

Inhibition of DNA synthesis in mouse lymphosarcoma LS/BL cells by fluorocitrate.

Fluorocitrate is a specific inhibitor of aconitase activity (EC 4.2.1.3). It causes an inhibition of citric acid cycle reactions and consequently reduces the oxygen consumption, as well as the total volume of oxidative phosphorylations. Experiments using 3H-thymidine incorporation into mouse lymphosarcoma LS/BL cells proved that the in vitro blocking of citric acid cycle by fluorocitrate (3.6 and 7.2 mM) was accompanied by a decrease in DNA synthesis by 40 to 60 percent, as compared to control cells. A similar inhibitory effect upon DNA synthesis was also found in cells cultured in the abdominal cavity of host mice injected intraperitoneally with 5 mg./kg. of sodium fluoroacetate. Following the injection, fluorocitrate is formed in vivo by way of Peters' lethal synthesis.

Aconitate Hydratase↗
PubMed1975

Radioprotective and toxic effects of a mixture of AET and 5-methoxytryptamine in mice.

The authors studied the radioprotective efficacy and toxicity of an AET + 5-methoxytryptamine mixture and its effect on the course of respiratory exchange, using different weight ratios of the two components. The optomum was found to be 150 mg AET/kg b.w + 25 mg 5-MOT/kg b.w. This mixture gave very good protection in the supralethal exposure range and markedly prolonged its duration. The high toxicity of this mixture was abolished by the pre-administration of glutathione. Raised and longer protection was also manifested in the course of respiratory exchange, showing that an association exists between changes in energy metabolism and raised radioresistance of the organism.

5-Methoxytryptamine↗
PubMed1975

Dynamic characteristics of a metabolic reaction of mice with different responses to irradiation.

The course of the reaction of mice placed in a metabolic chamber and afterwards irradiated with an exposure dose of 610 R was studied by assessing total oxygen consumption and the size of its fluctuation. Fluctuation was greater in non-survivors than in survivors in the initial phase of the metabolic reaction only (P is less than 0.05), while the mean oxygen consumption values for the two groups were the same, In the distribution of the individual values there were more non-survivors in the frequency class with a high fluctuation level and, conversely, more survivors in the low level class (P is less than 0.01). Fluctuation during the studied reaction was more variable in survivors, despite its lower level, than in non-survivors. The reciprocal relationship between the size and fluctuation of oxygen consumption, determined for the whole series of experimental mice at given stages of the metabolic reaction, is linear. Attention is drawn to the association between changes measured in the metabolic rate and motor activity and to the possibility that it is determined by the individual's type of nervous activity.

Animals↗