[Improved method of ultrasonic diagnosis of maxillary sinus diseases in children]. / Usovershenstvovannaia metodika ul'trazvukovoi diagnostiki zabolevanii verkhnecheliustnykh pazukh u detei.

A modified technique of ultrasonic diagnosis of accessory nasal sinus diseases based on an analysis of the profile of echograms has been developed. A correlation between the profile and pathological changes in the Highmore antrum has been found. It has been shown that the cystic fluid has a characteristic difference between the intensity of the start and echo impulses. Echograms of a cyst and its capsule reveal that they are significantly heterogeneous. Pus is characterized by a pronounced ultrasound absorption, fluid pus and thick pus showing different response. Plasma and blood are characterized by a significant ultrasound absorption and sufficient homogeneity. An interpretation of an echogram obtained under clinical conditions is presented.

[The use of melamine-formaldehyde latex in the automated analysis of immunocompetent cells]. / Ispol'zovanie melaminoformal'degidnogo lateksa v avtomatizirovannom analize immunokompetentnykh kletok.

The optimization of the loading of monodispersed melamine-formaldehyde latex with fluorochrome has permitted its use as indicator material, equally suitable both for the visual evaluation of the reaction of phagocytosis and for the automated evaluation of this reaction by means of a scanning fluorescent microscope. The study has shown the possibility of using fluorescent melamine formaldehyde latex for the evaluation of the phagocytosis of mouse peritoneal macrophages and human blood cells, as well as the analysis of the surface receptors of immunocompetent cells.

[A comparative study of the IgG-binding components of the membrane in different strains of Staphylococcus aureus using the indirect hemagglutination reaction and an immunofluorescence method]. / Sravnitel'noe izuchenie IgG-sviazyvaiushchikh komponentov obolochki razlichnykh shtammov Staphylococcus aureus s pomoshch'iu reaktsii nepriamoi gemaggliutinatsii i immunofluorestsentnogo metoda.

A comparative estimation of IgG-binding activity of 85 S. aureus clinical strains was carried out by the method of indirect hemagglutination reaction. The S. aureus strain selected as a result of screening was found to exceed by more than an order the Cowan I strain obtained from the L. A. Tarasevich State Institute of Standards and Control of the Medical Biological Drugs in the IgG-binding activity. It was established that the ratio of two types of IgG-binding sites located on the S. aureus surface, varied depending on the strain, composition and quality (liquid or solid) of the culture medium.

[Distribution of aromatic amino acid residues according to the character of their microenvironment and the dynamics of the conformational properties of the protein molecule C1q]. / Raspredelenie aromaticheskikh aminokislotnykh ostatkov po kharakteru mikrookruzheniia i dinamicheskie konformatsionnye svoistva molekuly belka C1q.

The distribution of aromatic amino acid residues in the Clq molecule according to their microenvironment was studied by the methods of difference thermal and solvent perturbation spectroscopy, fluorescence and chemical modification. Out of the three tryptophan residues located in the globular part of A- chain one residue is completely exposed on the surface, while other two are only partially exposed to a solvent. Chemical modification of tryptophanyls significantly affects the hemolytic activity of Clq, that may evidence for the formation of immunoglobulin-binding sites with participation of A- chains as well as for the location of, at least, one of the three tryptophan residues in A- chain close to the immunoglobulin-binding site or even participation in the formation of the latter. The average rotation relaxation time of tryptophanyls estimated from the data on fluorescence is 210 +/- 10 ns. It specifies mobility of the globular and collagen parts of the molecule.

[Conformation changes in the mechanism of cryoprecipitation of human monoclonal immunoglobulin M]. / Izuchenie konformatsionnykh izmenenii v mekhanizme kriopretsipitatsii monoklonal'nogo immunoglobulina M cheloveka.

The role of conformational changes in the mechanism of cryoprecipitation of human monoclonal immunoglobulin M (IgM) was studied. It was demonstrated that the variable moiety of the Fab-region of cryo-IgM has a site which comprises 5 to 6 charged amino acid residues. This site is responsible for intermolecular electrostatic interactions which lead to the formation of a precipitate with a decrease in temperature. This interaction is cooperative and stabilized by dipole molecules of H2O. The chain growth during aggregation is nuclear. The primary nucleus contains three IgM macromolecules. stability of the three-molecule nucleus is provided for by 16--17 intermolecular links. Using circular dichroism and fluorescent methods, it was found that the formation of a cryoprecipitate is accompanied by ionic pair release and conformational changes.

[Interaction of natural and synthetic polynucleotides with liposomes in the presence of divalent cations]. / Vzaimodeistvie prirodnykh i sinteticheskikh polinukleotidov s liposomami v prisutstvii dvukhvalentnykh kationov.

The formation of complexes of polynucleotides (DNA, poly A.poly U) with liposomes from egg lecithins, L-alpha-phosphatidylcholine, dimirystoyl and other lipids in the presence of divalent cations was studied by differential scanning microcalorimetry circular dichroism and turbidimetry. It was shown that the secondary structure of polynucleotides (double or triple helix) was necessary for the formation of these complexes. This structure was partially destroyed during formation of complexes. It was shown, that three main types of lipids, i.e. phosphatidylcholine, phosphatidylethanolamine and sphingomyelin participate in interactions between liposomes, polynucleotides and Mg2+.

[Manifestations of domain organization of the Staphylococcus aureus protein A during heat denaturation of its structure]. / Proiavlenie domennoi organizatsii belka A Staphylococcus aureus pri teplovom razrushenii ego struktury.

Melting of protein A from Staphylococcus aureus has been studied in neutral medium by the methods of microcalorimetry and circular dichroism. The melting process of protein A is shown to consist of, at least, 5 independent transitions. The transition with the heat absorption maximum at 38 degrees is ascribed to the melting of the C-terminal domain of protein A. The analysis of amino acid sequences has shown the existence of structural basis for differences in heat stability of the Fc-binding domains of protein A.

[The role of the immunoglobin G "hinge" region in heat aggregation and activation of complex-formation]. / Rol' "sharnirnoi" oblasti immunoglobulinov G v teplovoi agregatsii i aktivatsii kompleksoobrazovaniia.

A high degree of correlation between the capability of subclasses of human immunoglobulins G to form aggregates due to thermal treatment, and their complement-binding activity was established. On the basis of the experimental data obtained by the methods of light scattering, circular dichroism, microcalorimetry, it was supposed that "hinge" region of immunoglobulins G participates in the initial stage of thermal aggregation and in the activation of the process of complement binding.

Dynamic properties of bacteriorhodopsin in purple membranes upon heat treatment.

Reversible temperature-dependent conformational changes in bacteriorhodopsin of the purple membranes from Halobacterium halobium have been studied by the method of deuterium exchange. A noticeable increase in the mobility of structured peptide groups in bacteriorhodopsin was revealed upon reorganization of the supermolecular structure at about 60 degrees C. In the supermolecular structure formed, bacteriorhodopsin molecules have no contacts with external medium at 75-80 degrees C. Membrane destruction results in a drastic increase in molecular mobility within the narrow temperature range 100-110 degrees C. The effects observed are induced by predenaturation changes in the bacteriorhodopsin structure and rearrangements in the structure of a protein-lipid complex. The temperature dependence of the number of peptide groups involved in reversible conformational rearrangements is in good agreement with the microcalorimetry data.

Age-dependent changes of protein structure. The properties of young and old rabbit aldolase are restored after reversible denaturation.

The significantly increased helical content is observed in muscle aldolase molecule of old rabbits. The unfolding and refolding of protein conformation followed by circular dichroism, fluorescence and enzyme activity showed the recovery of initial conformation after the denaturation. The protein folds into the form that existed prior to denaturation--"young" into "young" and "old" into "old"--the conformational differences between them being restored. This suggests that the primary structure modifications prior to the folding of the native protein conformation are the origin of the age-dependent differences of aldolase structure and function.

Calorimetric study of the complexes between polyuridylic acid and adenylic nucleotides.

Soluble complexes of poly (U) and adenylic nucleotides in NaCl solutions were studied by scanning microcalorimetry. The melting enthalpies, delta Hm, of poly (U) complexes with adenosine, 2',3' -cAMP, 2'(3')-AMP, 5-AMP, ADP, ATP in 1 M NaCl are 50.5; 45.0; 42.9; 28.6; 26.1 and 25.6 kJ/mole triplets, respectively. Delta Hm is independent of the complex melting temperature, Tm. The calorimetric enthalpies are considerably lower than the apparent delta Hv.H. obtained from Tm dependence on free monomer concentration. The enthalpy of complex formation in 1 M NaCl depends neither ob the number nor on the degree of ionization of the phosphate groups but is essentially determined by their 5' - or 2'(3')-position. In contrast to 2'(3')- AMP. 2 poly (U), delta Hm of 5'AMP. 2 poly (U) increases considerably at lowering Na+ concentration. The enthalpy of poly (U) double helix melting in 1 M NaCl is 8.8 kJ/mole pairs which is 2.5 times lower than that in MgCl2 solutions.

[Role of conformational lability in the hydrolysis of ATP by myosin]. / Rol' konformatsionnoi podvizhnosti v reaktsii gidroliza ATF miozinom.

Melting temperature of myosin Tm against the concentration of D2O in the system was studied. The D2O/Tm relationship is analogous to that between the kinetics isotope effect and the volumic fraction of D2O in the system. This similarity as well as the difference between the observed kinetic and thermodynamic isotopic effects and the theoretical ones make us suggest that the conformational changes in myosin during ATP hydrolysis are rather substantial.

[Conformation of cytochrome b5 in soluble form and incorporated into artificial membranes]. / Konformatsionnoe sostoianie rastvorimogo i vstroennogov iskusstvennuiu membranu tsitokhroma b5.

It was shown that 35% of the peptide groups, which form the right alpha-helices, are presented in the soluble fraction of cytochrome b5. The incorporation of cytochrome b5 into egg lecithine liposomes increases the number of alpha-helices up to 51%. On the contrary, the cytochrome incorporation into microsomal lipid liposomes slightly increases the degree of spiralization. The reduction of cytochrome b5 haem slightly decreases alpha-helices in the soluble haemoprotein as well as in the one incorporated into the artificial membrane irrespective of its phospholipid content.

[Conformation and thermal stability of soluble and liposomal forms of cytochrome P-450]. / Konformatsiia i teplovaia stabil'nost' rastvorimogo i vstroennogo v membranu liposom tsitokhroma P-450.

This secondary structure of soluble cytochrome P-450 and the one incorporated into liposomes from egg lecithin and microsomal lipids has been studied. Using circular dichroism and infrared spectroscopy, it was shown that about 60% of alpha-helices are presented in the structure of haemoprotein and the rest 40% have the structure of statistical coil. The binding of haemoprotein with the type II substrates--octylamine and diaminooctan, slightly increases alpha-helices in soluble cytochrome P-450. The type I non-polar substrates--hexane and cyclohexane--do not change the conformation of isolated enzyme. Cytochrome P-450 incorporated into the artificial membranes of phosphatidyl choline and microsomal phospholipid has almost identical secondary structure as does the soluble one. Data from circular dichroism suggest that the binding of the types I and II substrates to cytochrome P-450 incorporated into lecithin liposomes and microsomal lipid liposomes does not change the conformation of the polypeptide chain. The reduction of cytochrome P-450 haem increases the degree of alpha-spiralization by 10% for soluble haemoprotein and by 5% for the membrane-bound enzyme. The thermal stability of soluble and liposomal forms of cytochrome P-450 was investigated by circular dichroism technique. The effective values of enthalpy and the temperature transition of soluble cytochrome P-450 at pH 6.9, 7,6 and 7,9 are 78, 80 and 78 kcal/mol and 47,7 degrees, 45,2 degrees and 42,4 degrees, respectively. The enzyme incorporated into the phospholipid vesicles is much more stable. The cooperative transition of soluble cytochrome is clearly expressed in contrast to the one of the membrane-bound enzyme.

Thermal stability of soluble mitochondrial H+-ATPase.

ATPase melting has been studied by circular dichroism and differential scanning microcalorimetry. Decomposition of the alpha-helix of H+-ATPase (in which about 80% of the peptide groups of the enzyme are involved) following thermal treatment is shown to proceed gradually, beginning with room temperature. Effect of nucleotides upon melting is detected in the range of 20 degrees--40 degrees C. Above 40 degrees C, the pattern of thermal decomposition of the three-dimensional structure of H+-ATPase is independent of the nature of nucleotides present. Highly stable alpha-helical sites have been found in the enzyme molecule. Possible mechanism of formation of such sites is discussed, and the results obtained are compared with data on thermal stability of ATPase from thermophilic bacteria. Structural changes in the molecule following thermal treatment are compared with ATPase activity changes under similar experimental conditions.

[Chemical modification of ferricytochrome c by N-(2,2',5,5'-tetramethyl-3-carboxypyrroline-1-oxyl)-imidazole]. / Khimicheskaia modifikatsiia ferritsitokhroma s N-(22',5,5'-tetrametil-3-karboksipirrolin-1-oksil) imidazolom.

Chemical modification of pig heart ferricytochrome C by the paramagentic analog of N-acetylimidazole-N-(2,2',5,5'-tetramethyl-3-carboxypyrroline-1-oxyl)-imidazole has been studied. Two main modified preparations, both with the single spin label per molecule, have been isolated by means of chromatography on CM-Sephadex C-25. The study of UV-difference spectra of the SL-preparations versus native Cyt C, the spectrophotometric titration of the tyrosine residues in modified proteins and the study of their reaction with hydroxylamine allow to conclude that one of these preparations (fraction II) is lysine modified Cyt C-SL(Lys)-Cyt C and the other (fraction III) is tyrosine modified protein-SL(Tyr)-Cyt C. From the present results and the data available in literature the most probable location of the modification sites in the three-dimentional structure of Cyt C is Tyr-74 in SL (Tyr)-Cyt C and one of the neighbouring lysil residues Lys 72 or Lys 73 in SL (Lys)-Cyt C on the molecular surface. From the absorbtion and CD-spectra of the modified and native Cyt C in the spectral interval 190--450 nm and from the high resolution PMR data the conclusion has been made that the chemical modification does not alter the immediate vicinity of the heme group and the molecular structure of Cyt C as a whole. Therefore both SL-modified preparations might be useful for the conformational and functional investigations of Cyt C.