[Lipopolysaccharide changes in smooth-type avirulent Shigella in comparison with initial virulent strains]. / Izmeneniia lipopolisakharidov u avirulentnykh shigell gladkogo tipa po sravneniiu s iskhodnymi virulentnymi shtammami.

The comparative study of the lipopolysaccharides (LPS) of virulent and avirulent strains of S. sonnei, phase I (smooth colonies), has been made. Electrophoresis of LPS and subsequent densitometry of electrophoregrams have revealed the increase of the fraction of long 0-chains with a considerable number of recurring elements in 2 out of 3 LPS preparations obtained from avirulent shigellae. In mice immunized with these LPS preparations a considerably greater number of antibody-producing cells can be detected in Jerne's test on sheep red blood cells (SRBC) sensitized with the LPS of a virulent strain than on those sensitized with the above LPS preparations. Long 0-specific chains supposedly inhibit the fixation of individual complement components on the corresponding sensitized SRBC. The LPS of the third avirulent strain of S. sonnei, phase I, with transposon integrated into its genome, which has led to the formation of the avirulent variant of a previously virulent strain, seems to contain fine structural differences from the initial virulent strain. The immunogenicity of the LPS of this avirulent strain is greatly (3-4 times) decreased, which is manifested by the number of antibody-producing cells detected in Jerne's test on SRBC sensitized with LPS preparations obtained from these two strains.

[Changes in antigenic properties of lipopolysaccharides of Shigella sonnei phase I having lost the virulence due to transposon integration into the invasiveness plasmid PSS120]. / Izmenenie antigennykh svoistv lipopolisakharida shigell Zonne I fazy, utrativshikh virulentnost' v sviazi s integratsiei transpozona v plazmidu invazivnosti PSS120.

A nonvirulent strain of Shigella sonnei phase I has been obtained by integration of the transposon Tn5 into the invasiveness plasmid pSS120 in the virulent strain and designated NR18. The presence of the plasmid pSS120 in both strains results in the similar morphology and bacterial ability to agglutinate in the presence of antiserum to Shigella sonnei phase I antigen. The lipopolysaccharide preparations from the virulent and nonvirulent strains give the similar reactions with the antiserum in the reaction of hemagglutination. However, in the reaction of passive local hemolysis in the gel (Jerne reaction) the significant difference is revealed in the immunogenicity of the preparations, with the preparations from the virulent strain being 4-5 fold more immunogenic. In crossreaction, the antibodies secreted by the mouse spleen cells immunized by LPS from the virulent strain show a weak reaction with the ram erythrocytes sensitized by the LPS of the nonvirulent strain. Thus, the biological changes in the LPS of the nonvirulent strains that are, evidently, the consequence of the structural changes, are identified only by the most sensitive immunological techniques.

[The nature of functional groups in the active center of antitumor glutamin-(asparagin-)ase]. / O prirode funktsional'nykh gruppy aktivnogo tsentra antiopukholevoi glutamin(asparagin)azy.

The effect of two reagents on glutamin (asparagin) ase from Pseudomonas aurantiaca-548 has been studied. 2,3-butanedione which modified arginine residues was ineffective for the inactivation of the enzyme. The enzyme was completely inactivated in the presence of N-ethyl-5-phenylisoxazolium-3'-sulfonate (Woodward's reagent K). The effects of pH, reagent concentration, competitive inhibitors and their analogues on the rate or degree of enzyme inactivation were studied. The experimental results suggest that the carboxyl groups localized at the active site of glutamin (asparagin) ase are probably essential for the substrate binding.

Thymus-independent antibody production to the antigen of Rickettsia prowazekii.

Antibody production has been studied in cotton B-rats and in CBA B-mice during immunization with chemical typhus vaccine (CTV) and during infection with Rickettsia prowazekii. Studies of the immune response to rickettsial antigen in T-deficient animals have shown a high immunogenicity of CTV and independence of antibody production on T-lymphocytes. Active antibody synthesis was also observed in B-rats and B-mice during Rickettsia prowazekii infection. The absence of T-lymphocyte dependence in experimental animals was tested by administration of sheep red blood cells (SRBC).

6-diazo-5-oxo-L-norleucine and azaserine as affinity inhibitors of glutamin(asparagin)ase.

Incubation of homogeneous glutamin(asparagin)ase from Pseudomonas aurantiaca with 6-diazo-5-oxo-L-norleucine (DON) and azaserine leads to an almost complete inactivation of the enzyme. The inactivation process in both cases involves the step of reversible binding of the enzyme with the inhibitor into a complex and subsequent modification of the enzyme within this complex. The data on saturation of the enzyme by low concentrations of inhibitors, the protective effect of substrate and its analogs as well as of the competitive inhibitor and product of the enzymatic reaction, L-aspartate, suggest that the modification of functional groups takes place in the enzyme active site. The presence of essential threonine hydroxyl groups in/or near the enzyme active site is surmised.

[Reaction of loose connective tissue fibroblasts after poly-4-vinylpyridine administration]. / Reaktsiia fibroblastov rykhloi soedinitel'noi tkani na vvedenie poli-4-vinilpiridina.

Mice were injected with poly-4-vinylpyridine at a dose known to be effective for immunogenesis stimulation. Within 24 hours after the injection fibroblasts reacted by dendrit production, cytoplasm vacuolization and clasmocytosis. 2-3 days after the polymer injection the fibroblast cytoplasm was restored. The immunofluorescence employed rabbit serum natural antibodies to fibroblast antigens. The reaction observed may be used for the estimation of biological polymer activity.

[Inactivation of microbial glutamin-(asparagin-)ase by azaserine and 6-diazo-5-oxo-L-norleucine]. / Inaktivatsiia mikrobnoi glutamin(asparagin)azy azaserinom i 6-diazo-5-okso-L-norleitsinom.

The effect of substrate analogues on glutamin-(asparagin-)ase from Pseudomonas aurantiaca-548 has been studied. The enzyme was demonstrated to be highly sensitive to the the action of 6-diazo-5-oxo-L-norleucine and azaserine. L-isomers of glutamine, aspartate, glutamate and several other substrate analogues with free alpha-amino groups protected the enzyme against the inhibitory DON effect. Thus, thorough preliminary selection of appropriate inhibitors, their dosage and treatment duration is needed for the recommendation of combined enzyme-inhibitor application in anti-tumour chemotherapy.

[Thermostabilization of glutamin(asparagin)ase from Pseudomonas aurantica BKMB-548]. / Termostabilizatsiia glutamin(asparagin)azy iz Pseudomonas aurantiaca BKMB-548.

In studies on kinetics of thermoinactivation of glutaminase (asparaginase) from Ps. arantiaca BKMB-548 at 50 degrees and pH 7.0 in presence or in absence of L-glutamate the enzyme inactivation was found to obey the first order equation. Both the glutaminase and asparaginase activities decreased at a similar rate. L-Glutamate stabilized the enzyme due to direct interaction with its molecule. Stability of the complex formed was evaluated quantitatively. L-Glutamate reacted apparently with a specific site on the surface of the enzyme molecule; Kdiss was 0.42 +/- 0.03 mM at pH 7.0 and 50 degrees. No cooperative effect was found. L-Aspartate protected the enzyme completely; stabilizing effects of L-cysteine, L-serine and glycine were similar to the effect of L-glutamate (94%, 84%, 83% and 82%, respectively). At the same time, glutarate, succinate, alpha-ketobutyrate, alpha-ketoglutarate, gamma-aminobutyrate and N-benzoyl glutamate did not exhibit the stabilization effect. The data obtained suggest that the high stabilizing effect might exhibit only the substances containing simultaneously free alpha-NH2 and alpha-COOH groups in a molecule, whereas presence of COOH groups at beta--or gamma-carbon atoms was not essential for the stabilizing effect.

[Antigen isolation from Rickettsia prowazekii cultured in FL cells and its use in the macrophage migration inhibition reaction]. / Poluchenie antigena iz rikketsii Provacheka, kul'tiviruemykh v FL-kletkakh, i ispol'zovanie ego v reaktsii ingibitsii migratsii makrofagov.

An antigen obtained from R. prowazekii cultivated in hydrocortisone-treated FL-cells possesses activity determined in the complement fixation test and the macrophage migration inhibition test. Such antigen can be used in the macrophage migration inhibition test with macrophages obtained from animals immunized with the preparations of rickettsial egg cultures.

Role of T lymphocytes in Rickettsia conorii infection.

Adoptive transfer of T lymphocytes harvested from spleen of Rickettsia conorii-infected DBA/2 mice to intact and cyclophosphamide- (CPA-) pretreated syngeneic mice protected the latter from lethal infection caused by R, conorii. Protection from infection was not observed in recipient mice given immune serum or B lymphocytes and macrophages from the spleens of convalescent mice. The protective effect was most pronounced after intravenous transfer of lymphocytes obtained from donor mice on day 14 post infection. Lethal infection was not prevented by transfer of lymphocytes harvested on day 50 p. i., although at this interval the donor mice were still resistant to reinfection with F. conorii.

Role of macrophages in infection with Rickettsia conorii.

Macrophages obtained from the abdominal cavities and spleens of DBA/2 mice and guinea pigs convalescent after Rickettsia conorii infection digested the rickettsiae in vitro more actively than those from uninfected animals. The activation of macrophages was manifested by their capacity to inhibit replication of the rickettsiae and to digest them as well as by their resistance to the toxic effect of rickettsiae. Visual observations and bioassays showed that a portion of the rickettsial population survived in the culture producing no toxic effect on the cells which could be readily passaged.

Differences in the susceptibility of mouse lines to the rickettsial pox agent.

A definite correlation between the susceptibility of spleen macrophage cultures derived from a highly susceptible mouse line (C57Bl/6) and a line with low susceptibility (DBA/2) and the susceptibility of these mouse lines to infection with Rickettsia acari was established. Intensive replication of the rickettsiae in cultures from highly susceptible animals caused marked disorders in cell metabolism and eventually death of the culture. Cell cultures derived from resistant mice gradually eliminated the rickettsiae by intracellular digestion; necrobiotic changes in them were insignificant.

[Erythrocyte antigen: isolation, biochemical and immunologic properties]. / Eritrotsitarnyi antigen: vydelenie, biokhimicheskie i immunologicheskie svoistva.

The authors suggest a simple method of obtaining erythrocytic antigen in considerable amounts. This antigen is of stromal origin, contains from 10 to 20% protein, and is relatively homogenous. With the concentration of from 1 to 50 microgram by protein the preparation represents a transparent solution; with greater concentrations the antigen is white, turbid, but is well dissolved and convenient for administration to the animals. In case of a single administration without any adjuvants the antigen is highly immunogenic in low doses by protein. To the optimal immunizing dose of erythrocytes (5 X 10(8)) correspond about 100 microgram of the antigen by protein. The primary response to the antigen is similar to the response to sheep red blood cells (SRBC). It is exceedingly effective for the formation of immunological memory. The level of secondary responses in the adoptive transfer to all the EAG doses always exceeded the secondary response to SRBC. By adding EAG into agar during the local hemolysis in gel test determined the avidity of the antibodies synthesized at various periods of the immune response to SRBC.

[Intracellular development of Rickettsia]. / Vnutrikletochnoe razvitie Rikketsii.

Microcinematography, cytological and cytochemical studies revealed new features of D. sibericus, D. murinus, and R. tsutsugamushi biology, mainly a very active movement in the cell. In contrast to D. sibericus, development of D. murinus and R. tsutsugamushi in cells is characterized by severe irritation of the infected cells early in the infection, a greater speed of movement of rickettsiae and their active release from the affected cells, as well as the development of necrobiotic changes in the latter. The mitotic activity of the cells increased early in cultures infected with Cox. burneti, R. prowazeki, D. sibericus, and T. tsutsugamushi. Subsequently, cell nuclei shrink and different cytotic changes develop in various rickettsia. Studies on the metabolism of the affected cells revealed activation of nucleic metabolism and redox enzymes associated with mitochondria in the course of the first 3 days followed by a low activity in 5 postinfection days. The lysosomal apparatus of the cells underwent drastic changes and the activity of acid phosphatase increased markedly with further elevation in the permeability of lysosomal membranes.