Comparative study of the transformation of various thymidine kinase-deficient human and animal cell lines with the thymidine kinase gene of the Herpes simplex virus

The comparative study of transformation of four thymidine kinase deficient cell lines (mouse mammary carcinoma cell line FS tk-; rat cell line Rat-2tk-; mouse cell line Ltk-, clone D1; human cell line 143tk-) with the thymidine kinase cloned gene of Herpes simplex virus 1 was undertaken. The differences in efficiency and optimal conditions of transformation were shown for these cell lines. The advantages and disadvantages of the cell systems examined for the use in experiments for transformation and cotransformation of cultured cells with isolated genes are discussed.     

Binding of K 1-3 and K 4 fragments of plasminogen containing lysine-binding sites with fibrinogen and its fragments

Interaction of plasminogen K 1-3 and K 4 fragments containing lysine binding sites with fibrinogen and its fragments has been investigated. It has been established that K 1-3 fragment binds to fibrinogen and its E and DL fragments. K 4 fragment does not bind to E and DL fragments, but it interacts with fibrinogen. K 4 fragment does not interact with early fibrinogen proteolysis X2 fragment which differs from the native molecule of fibrinogen in the alpha C domain absence. The results obtained indicate that lysine binding sites located at plasminogen K 1-3 and K 4 fragments correspond to different fibrinogen molecule centres. The centre complementary to K 4 fragment lysine binding sites could be located at the fibrinogen alpha C domain.     

Streptokinase immobilization in insoluble carriers, and properties of the immobilized protein

Immobilization of streptokinase was performed by bromine cyan-activated cellulose and by aminoethyl cellulose using glutaric aldehyde and N-cyclohexyl-N'-[2-(4-morpholinyl)-ethyl-carbodiimide. The specific activator activity of the immobilized streptokinase is 70-100% of that of free streptokinase. In multiple application of the immobilized protein preparations streptokinase obtained by bromine cyan-activated cellulose is the most stable: it retains more than 40% of initial activity after 10 repeated applications. The immobilized streptokinase is shown to be more thermostable as compared to the soluble one.     

Peripheral pool of CD8+ T-cells contains lymphocytes with antigen-specific receptors that recognize syngeneic MHC class II molecules

The capacity of T-lymphocytes to recognize "nonself" and tolerating "self" is formed as a result of positive and negative selection in the thymus. While obtaining and testing specificity of T-hybridomas, we demonstrated that the major part of peripheral pool of CD8+ T-lymphocytes carried receptors specific to "self" MHC class II molecules. Such an unexpected specificity of receptors has been found in some T-cell hybridomas produced by fusion of activated peripheral CD8+ T-lymphocytes with a tumor partner transfected by the coreceptor CD4 gene. The reactivity to "self" is not an experimental artifact due to an increased avidity of interaction of the hybridoma cells with antigen-presenting cells. Also, it is not an expression of reactivity of T-cells to superantigens, products of endogenous viruses of mouse breast cancer. The formation of a pool of such T-cells involves both cells with double receptor specificity and cells coexpressing two alpha-chains of T-cell receptor. Their appearance in the periphery can be due to the capacity of thymocytes differentiating in the direction of CD4+ cells to avoid negative selection via change of expression of coreceptor CD4 to CD8.     

Hybrids of human and monkey adenoviruses (adeno-adeno hybrids) that can reproduce in monkey cells: biological and molecular genetic peculiarities

A highly oncogenic monkey adenovirus SA7(C8) facilitates the reproduction of human adenovirus type 2 (Ad2) in monkey cells. Upon mixed infection of monkey cells with both viruses, these viruses recombine producing defective adeno-adeno hybrids Ad2C8 serologically identical to Ad2 and capable of assisting Ad2 to reproduce in monkey cells. Ad2C8 and Ad2 form an intercomplementary pair inseparable in monkey cells. Unlike oncogenic SA7(C8), Ad2C8 is a nononcogenic virus for hamsters but is able to induce tumor antigens of this virus (T and TSTA). Molecular genetic analysis of 68 clones of adeno-adeno hybrids revealed that the left part of their genome consists of Ad2 DNA, and the right part contains no less than 40% of the viral SA7(C8) genome where E2A, E3, and E4 genes are located. Apparently, the products of these genes contribute to the composition of adenoviral tumor antigens, while the E4 gene is involved in complementation of monkey and human adenoviruses and makes a contribution to host range determination of these viruses.     

Role of plasminogen/plasmin in functional activity of blood cells

The article deals with the data concerning structural peculiarities of plasminogen/plasmin molecule, which define the specificity of intermolecular interactions and provide the variety of its biological functions. The main principles of the modern classification of plasminogen receptors and factors, which modulate their expression, have been presented. We have considered the mechanisms regulating both plasmin formation and activity on the surface of cells, fibrin and proteins of extracellular matrix. The data of previous investigators and our own results, concerning the influence of plasminogen/plasmin on platelet aggregation induced by different agonists, have been summarized. The participation of plasminogen/plasmin in atherogenesis and angiogenesis mediated by endotheliocyte receptors has been discussed. Special attention was given to plasminogen/plasmin proinflammatory function, which is realized by regulatory processes of activation, secretion, migration and apoptosis of monocytes and macrophages.     

Glioma Cell and Astrocyte Co-cultures As a Model to Study Tumor–Tissue Interactions: A Review of Methods

Astrocytes are a dominant cell type that envelopes the glioma bed. Typically, that is followed by formation of contacts between astrocytes and glioma cells and accompanied by change in astrocyte phenotype, a phenomenon known as a ‘reactive astrogliosis.’ Generally considered glioma-promoting, astrocytes have many controversial peculiarities in communication with tumor cells, which need thorough examination in vitro. This review is devoted to in vitro co-culture studies of glioma cells and astrocytes. Firstly, we list several fundamental works which allow understanding the modalities of co-culturing. Cell-to-cell interactions between astrocytes and glioma cells, the roles of astrocytes in tumor metabolism, and glioma-related angiogenesis are reviewed. In the review, we also discuss communications between glioma stem cells and astrocytes. Co-cultures of glioma cells and astrocytes are used for studying anti-glioma treatment approaches. We also enumerate surgical, chemotherapeutic, and radiotherapeutic methods assessed in co-culture experiments. In conclusion, we underline collisions in the field and point out the role of the co-cultures for neurobiological studies.     

The effect of arginine on hydrolysis of fibrinogen by plasmin and mini-plasmin]

The rate of plasmin or Val442-plasmin catalyzed hydrolysis of fibrinogen decreases several times as affected by arginine in high concentrations. The enzyme is shown to be not inhibited by arginine. The observed effect is supposed to depend on saturation of the protein-proteins interaction sites located between 442 and 790 amino acid residues.     

Plasminogen-binding centers of molecules of fibrinogen, fibrin and products of their proteolysis

Using affinity chromatography, the binding of Lys-plasminogen to fibrinogen, fibrin and the consecutively formed products of their proteolysis was studied. The optimal conditions for this binding were elaborated, and the quantitative parameters of Lys-plasminogen binding to fibrinogen-Sepharose were determined. It was found that the interaction of Lys-plasminogen with fibrinogen- and fibrin-Sepharose is provided for by the lysine-binding sites of the proenzyme molecule. After partial hydrolysis of fibrinogen by plasmin, the amount of adsorbed plasminogen increases and the type of binding changes; part of the proenzyme molecules bind in the presence of 0.003 M 6-aminohexanoic acid, i.e., when lysine-binding sites appear to be blocked. A comparative study of plasminogen binding to fibrinogen fragments was carried out. The resistance of the complexes formed to the effect of 6-aminohexanoic acid and arginine competing for the binding sites was determined. The data obtained testify to the appearance of additional plasminogen-binding sites in the fibrinogen molecule during proteolysis. These sites are complementary for both lysine-and arginine-binding sites of the plasminogen molecule and are localized in the peripheral domains of the fibrinogen molecule.     

Microbial conversion of pregna-4,9(11)-diene-17alpha,21-diol-3,20-dione acetates by Nocardioides simplex VKM Ac-2033D

The conversion of pregna-4,9(11)-diene-17alpha,21-diol-3,20-dione 21-acetate (I) and 17,21-diacetate (VI) by Nocardioides simplex VKM Ac-2033D was studied. The major metabolites formed from I were identified as pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 21-acetate (II) and pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione (IV). Pregna-4,9(11)-diene-17alpha,21-diol-3,20-dione (III) and pregna-1,4,9(11)-triene-17alpha,20beta,21-triol-3-one (V) were formed in minorities. Biotransformation products formed from VI were pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 17,21-diacetate (VII), pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 21-acetate (II), pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione (IV), pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 17-acetate (VIII), pregna-1,4,9(11)-triene-17alpha,20beta,21-triol-3-one (V). The conversion pathways were proposed including 1(2)-dehydrogenation, deacetylation, 20beta-reduction and non-enzymatic migration of acyl group from position 17 to 21. The conditions providing predominant accumulation of pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 21-acetate (II) from I and pregna-1,4,9(11)-triene-17alpha,21-diol-3,20-dione 17-acetate (VIII) from VI in a short-term biotransformation were determined.