[Modification of placenta blood serum proteins under low temperature effect].

Changes in environmental physical and chemical factors upon freeze-thawing and low temperature storage of biological samples can result in impairments of protein structures. This work specifies spontaneous and diamide-induced protein aggregations of placenta blood serum stored at -20 degrees and -196 degrees C during 2 years with SDS-PAGE. It was shown that storage of placenta blood serum at low temperatures did not cause any quantitative and qualitative changes in fraction distribution of proteins denatured with SDS in comparison to the native samples which were not frozen. Application of beta-mercaptoethanol revealed that placenta blood serum proteins upon freeze-thawing did not form spontaneous aggregates linked by disulphide bridges. Oxidation of amino acid sulfhydryl groups induced by diamide and accompanied by high molecular aggregate formation proved to be a quite effective way for indirect estimation of structural changes in protein upon low temperature effects. In samples thawed after low temperature storage the protein aggregation with 4 microM diamide was significantly higher than in native serum. These discrepancies between native and frozen-thawed samples are stipulated by impairments of protein structure under low temperature and increased in accessibility of reactive SH-groups of proteins for oxidation with diamide. Structural changes in placenta blood serum proteins, which caused by low temperatures and revealed by elevated sensibility to diamide-induced aggregate formation, did not depend on temperature (-20 degrees and -196 degrees C) and storage terms (2 years and 3 weeks). They reflect protein reaction to freeze-thawing processes and could be sequence of ice crystal formation which takes place in unprotected media.

[Examination of low temperature effect on cord blood serum by microwave dielectric method].

The influence of the freezing velocities and final temperatures of storage on the complex dielectric permittivity of cord blood serum have been studied. On the temperature dependences of the dielectric permittivity the non-monotonous changes at the characteristic temperatures accompanying with the change of the activation energy of the water molecules dielectric relaxation were found out. The drastic deflection of the temperature dependence of ?' from the monotone curve at 15 degrees C region correlates with the fracture of Arrhenius plots of the dielectric relaxation time and viscosity at the same temperature. Slow freezing (1-2 degrees C/min) of cord blood serum results in ?' diminution in comparison with control, that testifies an increase of bound water amount because of loosening in this case the surface of biomacromolecule polypeptide chains. Rapid freezing (300-400 degrees C/min) results in ?' increase of serum, that is caused, apparently, by the cryoaggregation of biomacro-molecules, which can thus happen.

[Change in blood viscosity and hematocrit during cooling of an animal]. / Izmenenie viazkosti krovi i gematokrita pri okhlazhdenii zhivotnykh.

When studying temperature dependencies of rat's blood viscosity, cooled in vivo and in vitro, we have identified the differences in their nature. An attempt is made to evaluate contribution of hematocrit into a rise in the viscosity of rats being cooled.

[Thermotropic changes of certain characteristics of human blood]. / O termotropnykh izmeneniiakh nekotorykh kharakteristik plazmy krovi.

Viscosity and spectroscopic characteristics of blood plasma were studied in the temperature range from 0 to 40 degrees C. A correlation between thermotropic anomalies of plasma viscosity at 16-26 degrees C and 32-36 degrees C and a change in certain spectroscopic parameters were reported, which can be related to the re-structuring of intermolecular interactions in the system of plasma proteins.