Biomedical subjects

I A Kuznetsov

Publications and source records attributed to I A Kuznetsov.

40 records · Page 3Linked to original sources

PubMedDate not supplied

[Ion-exchange properties of DNA immobilized in acrylamide gel].

Ion-exchange of K+, Ca2+, Mg2+ and NH4+ on the Na+-DNA entrapped in acrylamide gel was studied. Under a definite percentage ratio between acrylamide and cross-linking agent (N,N'-methylenebisacrylamide) more than 95% of initial DNA was shown to be immobilized firmly and not to be washed out by salt solutions. Melting temperature and hypochromicity measurements of DNA extracted from the gel showed that denaturation of DNA has not taken place. The gel with immobilized DNA may be considered as ion-exchanger with phosphate fixed groups. It has been found that Mg2+, Ca2+, Na/, K+ and NH4+ are bounded with phosphate groups only, the degree of binding declines in the following order: Na+ less than or equal to K+ much less than Mg2+ less than Ca2+. The immobilization of DNA is suggested as a method of investigation of interaction between DNA and metal ions.

Acrylamides↗

PubMedDate not supplied

[Mathematical modelling of the metabolism of the radionuclide cesium-137. The calculation of the population risk].

Detailed mathematical analysis of the metabolism of cesium-137, which first appeared in the environment as a result of nuclear weapon testing in the atmosphere, made it possible to estimate the irradiation for the population of the U.S.A. with reference to sex and age during the entire life until death. In parallel, demographic analysis of mortality due to leucosis from 1950 until 1986 has shown cohorts of elevated mortality risk in two age groups: 0-1 and 45-54 years, starting from 1953. The radiation component of mortality was plotted for a set of cohorts as a function of the irradiation dose until the moment of death. Additional mortality risk was calculated for 1963 and 1967: 5.9 and 2.3 additional deaths per 1000 subjects per 1 Gy, respectively. The potential of demographic methods for assessment of the ecological situation has been shown.

Adolescent↗

PubMedDate not supplied

[Effect of the nature of a monovalent counterion on the secondary structure of DNA is aqueous solutions].

Doxyribonucleates (DNMe) and deoxyribonucleic acid (DNA) were prepared by the ion-exchange method from Na+-salt from chicken erythrocyte DNA (DNS). (Here Me+ means Rb+, CS+, Na+, or NH4+). It was found that in aqueous solutions of DNMe in which the concentration of nucleic phosphorus was 8-10(5) mole/1 and the supporting electrolyte contained as an impurity only, the secondary structure of DNA was partly restored. This was confirmed by low values of the atomic extinction coefficient (epsilon260(p) = 6800 1/mole-cm and by high values of the hyperchromicity coefficients (1-28). The melting temperatures, as well as the width of the melting transition calculated from the melting curves, did not depend on the nature of Me+. Abnormally high melting temperatures for aqueous solutions of DNMe were noted. It was shown that the DNS - DNA transition was accompanied by spectrum changes that are typical of the denaturation process.

Ammonium Chloride↗

PubMedDate not supplied

[The effect of the concentration and nature of 1-1-valent electrolytes on acid-base equilibrium in solutions of DNA].

The effect of concentration of LiCl, NaCl, KCl and NH4Cl on the potentiometric titration curves of chicken erythrocyte DNA has been studied. Two inflections have been found in the titration curves at pH 5 and pH 8, respectively. The ionization constant corresponding to the second inflection is slightly increased when the concentrations of NaCl, KCl and NH4Cl are increased. Both constants are increased when the concentration of LiCl is increased. It has also been found that the addition of LiCl to the DNA solution lowers the pH of the solution but the addition of the other investigated salts causes an increase of the pH of DNA solutions. The results found are used for discussion of the nature of acid groups of DNA.

Acid-Base Equilibrium↗