[The modification of method of erythrograms in patients under chronic hemodyalisis using hardware-controlled administration of laser low-angle light scattering].

The detailed analysis of structural characteristics of erythrocytes can be implemented with method of erythrograms. However its practical application in conditions of medical laboratory is a long and labor-intensive process of little avail for express-diagnostic. To register alterations of morphologic functional characteristics of erythrocytes in patients under chronic dialysis as compared with patients without renal pathology the new technique of low-angle light scattering never applied before for this purpose. Therefore, the purpose of this study is to resolve issue concerning validity of application of this technique for registration of alterations of functional status of erythrocytes in patients of department of chronic dialysis as compared with patients without renal pathology. The experiments concerning the identification of resistance of erythrocytes established significant differences for acid and ammonium models of lysis between patients without renal pathology and patients under chronic dialysis and also in patients in the course of dialysis session. In case of ammonium lysis, the differences were statistically significant between patients without renal pathology and patients under chronic hemodyalisis. In case of acid model, the differences were statistically significant in patients in course of dialysis session. Therefore, the application of low-angle light scattering technique is valid and informative for evaluation of functional status of erythrocytes in patients with terminal stage of chronic renal disease receiving treatment of regular hemodyalisis. The technique itself is low-cost, simple in application and easily reproduced. Therefore, the technique of low-angle light scattering can be applied both in research studies and clinical practice to identify characteristics of stability of membrane systems.

[Solid phase reaction of hemoglobin with spillover hydrogen].

The reaction of high-temperature solid-state catalytic isotope exchange (HSCIE) between bovine hemoglobin and spillover hydrogen (SH) was studied. It was shown that, in the field of subunit contact, there is a significant decrease in ability for hydrogen exchange by SH. A comparison of the distribution of the isotope label in the hemoglobin alpha-subunit was carried out for the HSCIE reaction with the hemoglobin complex and with the free alpha-subunit. To this end, enzymatic hydrolysis of protein under the action of trypsin was carried out. The separation of tritium-labeled tryptic peptides was achieved by HPLC. Changes in availability of polypeptide chain fragments caused by complex formation were calculated using a molecular model. The formation of the protein complex was shown to lead to a decrease in the ability of fragments of alpha-subunits MFLSFPTTK (A(32-40)) and VDPVNFK (A(93-99)) for hydrogen replacement by tritium by almost an order of magnitude; hence, their availability to water (1.4 A) twice decreased on the average. The decrease in ability to an exchange of hydrogen by spillover tritium on the formation of hemoglobin complex was shown to be connected with a reduction in availability of polypeptide chain fragments participating in spatial interactions of subunits with each other. Thus, the HSCIE reaction can be used not only for the preparative obtaining of tritium-labeled compounds, but also for determining the contact area in the formation of protein complexes.

[Solid phase isotope exchange with spillover hydrogen in amino acids, peptides, and proteins].

We summarize here information on the theoretical and experimental study of high-temperature (150-200 degrees C) solid phase catalytic isotope exchange (HTSPCIE) carried out with amino acids, peptides, and proteins under the action of spillover hydrogen. Main specific features of the HTSPCIE reaction, its mechanism, and its use for studying spatial interactions in polypeptides are discussed. A virtually complete absence of racemization makes this reaction a valuable preparative method. The main regularities of the HTSPCIE reaction with the participation of spillover tritium have been revealed in the case of peptides and proteins, and the dependence of reactivity of peptide fragments on the spatial organization of their molecules has been studied. An important peculiarity of this reaction is that HTSPCIE proceeds at 150-200 degrees C with a high degree of chirality retention in amino acids and peptides. This is provided by its reaction mechanism, which consists in a synchronous one-center substitution at the saturated carbon atom characterized by the formation of pentacoordinated carbon and a three-center bond between the carbon and the incoming and outgoing hydrogen atoms.

[Study of solid-phase catalytic isotopic exchange of hydrogen in alpha-conotoxin G1 under the effect of spillover-tritium]. / Issledovanie tverdofaznogo kataliticheskogo izotopnogo obmena vodoroda v konotoksine G1 pod deistviem spillover-tritiia.

Tritium-labeled alpha-conotoxin G1 with a molar radioactivity of 35 Ci/mmol and full biological activity (according to the binding to nicotinic acetylcholine receptor) was obtained by the high-temperature solid-state catalytic isotope exchange (HSCIE). The tritium distribution in the molecule of alpha-conotoxin G1 was revealed by 3H NMR spectroscopy. Tritium was found in all amino acid residues except for the Asn4-Pro5-Ala6 fragment. The data on the comparative reactivity of C-H bonds, the ab initio quantum-chemical calculation of the hydrogen exchange reaction, and the information on the spatial structures of alpha-conotoxin G1 in solution and in crystal state allowed us to establish that the reactivity of H atoms may be increased by their interaction with the electron donor O and N atoms at the transition state of the HSCIE reaction. A decrease in the rate of the HSCIE reaction could be caused by both a poor spatial accessibility of C-H bonds and a limited mobility of the peptide fragment containing these bonds.

[The use of ion-selective field transistors (ISFT) with photopolymerizable polyurethane membranes in nephrology for determination of potassium concentration (activity)]. / Primenenie ionoselektivnykh polevykh tranzistorov (ISPT) s fotopolime rizuemymi poliuretanovymi membranami v nefrologii dlia opredeleniia kontsentratsii (aktivnosti) ionov kaliia.

The applicability is examined of ion selective field transistors with photocurable polyurethane membranes to control of the electrolytic composition of dialyzing solutions used in artificial kidney apparatus, and also of plasma in patient treated by chronic hemodialysis. The short- and long-time characteristics of the efficiency of K(+)-selective field transistors in continuous contact with solutions. Comparative testing of such transistors and other sensing systems is made. It is demonstrated that a sufficient reliability of measurements in the range of physiological concentrations in combination with low cost provide the possibility of using K(+)-selective field transistors for monitoring of the potassium concentration both in dialyzing solutions and plasma in patients on chronic hemodialysis treatment.

[Na+ and K+ ion transport across the human erythrocyte membrane during the formation of nystatin channels under in-vitro conditions: the characteristics and an analysis of the processes]. / Transport ionov Na+ i K+ cherez membranu éritrotsiov cheloveka pri formirovanii v nei nistatinovykh kanalov v usloviiakh in vitro: nekotorye osobennosti i analiz protsessov.

The kinetic properties (the spontaneous lysis velocity, the time of achievement, and the concentration level of the stationary stage) are shown to be strongly different, while the human erythrocytes are resuspended in various salt media. The analysis of Na+ and K+ concentrations, under the effect of a polyene antibiotic nistatin, on the human erythrocytes as an integral kinetic function of time is carried out. The processes engaged in this kinetic function are characterized.

[An ionometric study of Na+ and K+ fluxes across the nystatin-modified human erythrocyte membrane]. / Ionometricheskoe izuchenie potokov Na+ i K+ cherez membranu éritrotsitov cheloveka, modifitsirovannuiu nistatinom.

The application of ion-selective electrodes is discussed for the kinetic determination of K+ and Na+ concentrations in the system, containing human red blood cells modified by nystatin. A series of mixed solutions was worked out, according to which the Na(+)-glass and the K(+)-thick membrane valinomycin electrodes were calibrated. The human erythrocytes were washed for 3 times with the basic solution (in mol per liter: 0.141 NaCl, 0.004 KCl, 0.002 CaCl2, 0.003 MgCl2, 0.01 glucose), and then were resuspended in it. The suspension was kept in a shaking bath at 37 degrees C. The modification of the cell membranes was performed by the introduction of different amounts of the antibiotic nystatin into the probe. Under these conditions the concentration of Na+ decreased, while K+ concentration increased. The values of concentration were registered ionometrically. In an hour and a half the stationary lines were obtained. Being based on the values of the stationary cation concentrations and the final concentrations, registered after the complete lysis of erythrocytes promoted by saponin, the ratio of cation fluxes across the modified membrane to the flux across the nonmodified membrane was calculated in accordance with the Hodgkin-Katz equation.