[Mechanisms of interaction of tetrahydrocortisol and its complex with apolipoprotein A-I and DNA regulatory cis-elements of CC(GCC)5/GG(CGG)5 type].

An IR-spectroscopy study of the mechanism of interaction between duplex CC(GCC)5/GG (CGG)5Li2 and tetrahydrocortisol or tetrahydrocortisol-apolipoprotein A-I complex revealed the formation of hydrogen bonds between the OH group of the tetrahydrocortisol A-ring and the C=0 group of cytosine or guanine. Tetrahydrocortisol forms hydrogen bonds with the PO2-group of the duplex and with the OH-group of monosaccharide. The interaction of tetrahydrocortisol and apolipoprotein A-I with the duplex occurs at the same active site, namely, with the C=O-group of bases. The order --> order structural transition takes place in the duplex under the action of tetrahydrocortisol. The order --> disorder structural transition takes place in the duplex under the action of tetrahydrocortisol-apolipoprotein A-I complex.

Changes in the secondary structure of highly polymeric DNA and CC(GCC)n-type oligonucleotides under the action of steroid hormones and their complexes with apolipoprotein A I.

A small-angle X-ray scattering study showed that the action of tetrahydrocortisol (THC) in complex with apolipoprotein A I (ApoA-I) on DNA leads to local melting of DNA. The most probable site of interaction between this complex and DNA is the (GCC)n-type sequence. Oligonucleotides (duplexes) of this type have been synthesized. It was demonstrated that the interaction of this oligonucleotide with the THC-ApoA-I complex leads to dissociation into complementary oligonucleotides. The latter ones also interact with the THC-ApoA-I complex. The kinetics of this multistep process is presented. The mechanism of interaction between hormones or their ApoA-I complexes and duplex CC(GCC)5.GG(CGG)5Li2 was studied using IR spectroscopy. It was shown that the interaction with THC or the THC-ApoA-I complex leads to the formation of hydrogen bonds between the OH group of the hormone A-ring and the C=O group of cytosine or guanine. Interaction with cortisol or the cortisol-ApoA-I complex leads to the formation of a hydrogen bond with the NH group of cytosine; in addition, THC and cortisol form hydrogen bonds with the PO2 group of the duplex and with the OH group of the monosaccharide. The interaction of ApoA-I with the duplex is accompanied by the formation of hydrogen bonds between the protein NH2 group and the C=O group of cytosine and the P=O group. The order-to-order structural transition takes place in the duplex under the action of THC or cortisol, with THC causing a higher ordering as compared to cortisol. The order-to-disorder structural transition occurs in the duplex under the action of the THC-ApoA-I, cortisol-ApoA-I, or ApoA-I complexes. Shifting the pH of the medium from 7.2 to 6.0 also leads to an order-to-disorder-type structural transition.

[Anomalous change in the specific conductivity in lipoproteins at around physiologic temperatures]. / Anomal'noe izmenenie udel'noi élektroprovodnosti v lipoproteinakh v oblasti fiziologicheskoi temperatury.

Studying the temperature dependence of conductivity sigma of rat and human lipoproteins and apoprotein A-I fractions revealed an anomalous region in the range of temperatures (35-38) +/- 0.5 degree C. The activation energy delta H and temperature coefficient sigma (delta sigma/delta T) on both sides of Tc and the heat of transition (delta H of transition) were calculated. In high-density human lipoproteins and apoA-I, the delta H value was found to be very low. Some mechanisms of interaction of hydrocortizone with high-density lipoproteins and apoA-I were studied by using IR-spectroscopy and conductometry were studied. It was found that the hormone considerably increases the portion of alpha-helices and beta-structures in these proteins (coil<-->alpha-helix and coil<-->beta-structure transitions). In this case, delta H value of the transition increases 13-fold; in addition, the abnormal region in apoA-I shifts 1-2 degrees C downwards. The anomalous changes in conductivity in the range of physiological temperatures in all lipoprotein fractions including apoA-I are probably related to structural phase transitions both in proteins and in phospholipids. Since the delta H value of the transition in human high-density lipoproteins is small, it is assumed that, in phospholipids of these particles, an orientation transition of the A<-->C smectic type takes place, which is assigned to the second-order phase transition. The structural transition in apoA-I can probably also be assigned to the second-order phase transition since the enthalpia of the transition is very small; presumably, this transition is related to changes in symmetry due to changes in the secondary structure (coil<-->beta-tructure transition).

[The specific electric conductivity of erythrocyte ghosts and hemoglobin in alcoholism]. / Udel'naia élektroprovodimost' "tenei" éritrotsitov i gemoglobina pri alkogolizme.

Changes of electric conductivity of red cell shadows and hemoglobin were measured in 36 alcoholics in various periods of abstinence. Electric conductivity varied as a function of temperature [sigma (T)]. It was compared with viscosity of red cell shadows suspensions and some indexes of red blood. The absolute values of red cell shadows and hemoglobin electric conductivity in alcoholics were higher than in controls in the whole temperature range (34-41 degrees C), being associated with decreased temperature coefficient (delta sigma/delta T). Over the treatment the absolute values of sigma decreased and delta sigma/delta T increased. In normal subjects the curves sigma (T) had a wave within the temperature range 37-38 degrees C which apparently reflected the phasic transition. In alcoholics the wave on the curves sigma (T) either disappeared or showed abnormal variations at 36 and 38 degrees C during the acute period of abstinence. Two weeks later the only variation at 37 degrees C appeared, its intensity increasing with prolongation of abstinent period. The changes seen in the curves sigma (T) correlated with peculiarities of red cell viscosity in the temperature range 34-41 degrees C.

[Changes in the structure of erythrocyte membrane and Na+. K+-ATPase activity in participants of the Soviet-Canadian trans-Arctic ski pass]. / Izmenenie struktury membran éritrotsitov i aktivnosti Na+, K+-ATFazy u uchastnikov sovetsko-kanadskogo transarkticheskogo lyzhnogo perekhoda.

Changes in the structure of erythrocyte membranes and kinetics of the membrane-bound enzyme Na+, K(+)-ATPase were measured in members of the Canadian-Soviet transarctic ski pass that took place in March-May 1988. Hemoglobin content decreased at the Pole (by 22%) and partially recovered in Canada; phospholipids in erythrocyte membranes diminished at the Pole and in Canada (by 30%). During the pass water concentrations in membrane proteins and phospholipids increased significantly. Changes were found in rheological properties of membranes, e.g., viscosity of erythrocyte shadow suspensions at critical temperature (Tc) which is within the physiological range (36-38 degrees C) and viscosity in the temperature range 34-42 degrees C. Electric conductivity varied as a function of temperature (delta sigma(T)]. At 36-38 degrees C sigma showed abnormal variations. The integral intensity of IR-spectra of absorption bands of COp (peptide bonds) and P-O-C (phospholipids) decreased and the half-width of the COp absorption band increased during the pass. The activity of Na+, K(+)-ATPase of erythrocyte shadows diminished which was in correlation with membrane structure changes. The temperature optimum of Na(+)-, K(+)-ATPase occurred at 37-38 degrees C and coincided with the region of the structural phase transition detected by the authors.

[Determination of the rate of utilization of glucose in a suspension of erythrocytes]. / Opredelenie skorosti utilizatsii gliukozy vo vzvesi éritrotsitov.

The authors suggest a new method for measuring the rate of glucose utilization in a cell (red cell) suspension, making use of interferometry. This method allows an easy examination of glucose utilization kinetics in time with but 1000 cells. Thermostatic control of the sample in the cuvette of the device permits detecting the temperature effects on glucose metabolism kinetics and thus define the temperature optimal for the process. A correlation was revealed between the point of structure phase transition in the red cell membrane and the optimal temperature for glucose utilization within the range of physiologic temperatures. This method may be useful in medical, biochemical, physiologic, and hematologic studies. The relative error of the technique is 3 percent.

[A rheological method of diagnosis of multiple sclerosis]. / Reologicheskii sposob diagnostiki rasseiannogo skleroza.

A new method for the diagnosis of disseminated sclerosis is suggested, based on the determination of the red cell suspension viscosity within the range of physiologic temperatures. Three viscosity peaks (maxima): at 35, 37-38 (the physiologic), and at 40 degrees C have been detected, probably corresponding to thermotropic phase transitions in red cell membranes. The curves reflecting the eta (t degrees C) dependence in disseminated sclerosis are characteristic of this disease and may be used as a test for the laboratory diagnosis of disseminated sclerosis.

[Rheological properties of erythrocyte suspensions in acute myocardial infarct in the physiological temperature range]. / Reologicheskie svoistva vzvesei éritrotsitov bol'nykh ostrym infarktom miokarda v oblasti fiziologicheskoi temperatury.

A study was made over time of the relationships between the viscosity of red cell suspensions and temperature [eta (T)] in normal subjects and patients with acute myocardial infarction. In normal subjects, the curves eta (T) have a bend within the temperature range 37-40 degrees C, which apparently reflects the phasic transition. In patients with myocardial infarction, the bend on the curve eta (T) either disappears or is undemonstrable during the acute period within the temperature range indicated. During transition to the subacute period (after 7-10 days), the bend on the curves reappears and then only variation of its pattern follows. The changes seen in the viscosities of red cell suspensions or red cell "shades" in the phasic transition area might be used for defining the stages, the time course, and prognosis of myocardial infarction.

[Mechanisms of the structural changes in erythrocyte membranes under the action of a shift in pH]. / Nekotorye mekhanizmy strukturnykh izmenenii éritrotsitarnykh membran pri deistvii sdviga pH.

The effect of pH shifts (5--10) on erythrocyte "ghosts" has been studied using the IR spectroscopy. The process of regulation has been shown to take place within pH 7.15--8 range involving both protein (transition testified by absorption band changes 1520, 1540, 1635, 1645, 1585, 1696, 3305 CM-1) and lipid membrane components testified by absorption band splits 1745, 1470, 1380, 720 AND 1242 cm-1. The transition from a lesser to a higher regulating state of membrane structure happens unevenly, since the above changes take place within the narrow pH 7.15--8 interval, near the homeostase limit, being never observed at pH 5--7.15 or 8--10. It is supposed that the increase in regulation of both protein, phospholipid and lipid membrane fields is of phasic nature which presumably constitutes the basis for pH action mechanism as a regulation factor.

[Conformational changes of erythrocyte membranes under the influence of biologically active substances]. / Konformatsionnye izmeneniia v membranakh eritrotsitov pri deistvii na nikh biologicheski aktivnykh veshchestv.

As a result of studying rabbit erythrocyte membranes by using infrared spectroscopy method the absorption bands 1635 cm-1, 1645 cm-1, 1685 cm-1, 1695 cm-1 that probably belong to beta-structure of protein membranes have been discovered. The increase of the intensity of these bands under the influence of carbochol or eserine on membranes corresponds to increasing the lobe of beta-structure. The increase of theintensity of absorbtion bands corresponding to beta-structure and the change of intensity of absorption band of amide-1 in the field 1650-1662 cm-1 relating to alpha-helical and unordered structure are due to alpha leads to beta-transition in contractile protein. The change of a half of width of absorption band of amides A 3310 cm-1 under the influence of carbochol and other substances on cholinereactive systems has been found. This change correlates with the intensity of bands corresponding to beta-structure.