CELL CULTURES PURITY CONTROL BY METHODS OF CLINICAL DIAGNOSTICS.

Cell cultures of higher organisms, especially cultures of human cells, are increasingly used in medical, pharmaceutical and scientific research. The main problem of cell cultures ­ non-lethal hidden contamination by mycoplasmas, viruses and outsider cell lines. As an available and reliable method for monitoring the purity of the cell cultures, we offer to use PCR kits designed and officially used in clinical diagnostics. We have tested 50 human cell lines using commercial diagnostic systems for detection of papilloma viruses, herpes viruses, adenoviruses, Mycoplasma hominis and total bacterial mass. Contamination in tested cell lines was not found. In the case of cell lines that contain integrated parts of viral genomes, the presence of the respective DNA sequences was confirmed. The proposed diagnostic systems can be effectively used to control the purity of cell lines, for qualitative detection of possible contamination, as well as for quantitative evaluations with calculation of viral load like it is practiced in clinical diagnostics.

[Association of leptin and total immunoglobulin E in obese patients].

We measured by the immunoenzyme assay serum levels of total IgE and leptin in 17 men and 95 women with non-alcoholic fatty liver diseases (NAFLD) and in 57 men and 25 women with alcoholic liver disease (ALD) in comparison with 454 control men and 74 women without hepatic pathology. It was shown that the total serum IgE level in patients with ALD (229.5 +/- 31.0 IU/l) is on the average twice that in NAFLD and control patients (89.7 +/- 15.0 and 96.2 +/- 16.0 IU/l respectively). The IgE level in patients with NAFLD is related to BMI and waist circumference (WC). Leptin levels in patients with NAFLD andALD are higher than in control and correlate with obesity signs in all three groups. They correlate with the IgE level and reach the maximum value at a concentration of total IgE over 100 IU/l in men with NAFLD and WC >94 and in women with BMI = >30.0 kg/m2 and WC >80 cm. Positive correlation between IgE, leptin level and obesity signs in men and women with NAFLD suggests that leptin may be a link between obesity, hepatosteatosis, and atopic diseases.

Heat shock protein DnaK--substrate of actin-specific bacterial protease ECP32.

It has been found that actin-specific bacterial protease ECP32 cleaves prokaryotic heat shock protein DnaK, which belongs to the family of heat shock proteins with molecular weight 70 kDa. We propose a new one-step method for DnaK purification using heat treatment. The technique yields ~1 mg of partially purified DnaK from 25 g of wet bacterial biomass. Polyclonal antibodies against DnaK were obtained. The degree of ECP32 catalyzed proteolysis of partially purified DnaK and that of DnaK in initial cell extracts was compared.

[Genetic manipulation and studying of differentiation properties of rat induced pluripotent stem cells].

Induced pluripotent stem (iPS) cells are derived from somatic cells reprogrammed to the pluripotent state by the induced expression of defined transcription factors, achieved for the first time by the seminal work of Takahashi and Yamanaka. This new type of pluripotent cells has offered new exciting options in regenerative medicine allowing the replacement of cells and organs with the patient's own cells thereby avoiding immunological complications. In order to develop such technologies in approved animal models, iPS cells were also generated from rodents. Of course, the most important model for studying of different diseases is rat. In this study, we present a method suitable for rat iPS cells genetic modification by stable transfection and show necessary conditions for the first stages of direct differentiation.

[The express-method of obtaining protease ECP32, the unique instrument in actin investigations].

The protease ECP32 is significant in investigations of actin, the basic protein of muscles and the cytoskeleton. The enzyme originates from the natural enterobacteria strain, which accumulates minor amounts of the protease intracellularly at the post-exponential growth phase. The limiting factor for biosynthesis is the amount of oxygen that has entered the medium. The highly effective method of two-phase cultivation with vigorous aeration at the exponential growth phase was recommended. Based upon the enzyme properties studied, there is a decreased potential for success when using either the affinity or one-stage purification methods. In order to overcome obstacles in the aforementioned methods, a simple method for ECP32 preparation and storage was developed, with purity and activity levels satisfying the requirements of actin structure and function investigations.

Purification and characterization of the proteinase ECP 32 from Escherichia coli A2 strain.

The proteinase previously described as an unidentified component of E. coli A2 extracts which hydrolyses actin at a new cleavage site (Khaitlina et al. (1991) FEBS Lett. 279, 49) was isolated and further characterized. A chromatographic method of proteinase purification was developed by which a purity of more than 80% was attained. The enzyme was identified as a single, 32 kDa polypeptide (ECP 32) by SDS-PAGE and non-denaturing electrophoresis as well as by ion-exchange chromatography and gel filtration. The N-terminal sequence of ECP 32 was determined to be: AKTSSAGVVIRDIFL. The activity of ECP 32 is inhibited by o-phenanthroline, EDTA, EGTA and zincone. The EDTA-inactivated enzyme can be reactivated by cobalt, nickel and zinc ions. Based on these properties ECP 32 was classified as a metalloproteinase (EC 3.4.24). Limited proteolysis of skeletal muscle actin between Gly-42 and Val-43 was observed at enzyme substrate mass ratios of 1:25 to 1:3000. Two more sites between Ala-29 and Val-30, and between Ser-33 and Ile-34 were cleaved by ECP 32 in heat- or EDTA-inactivated actin. Besides actin, only histones and DNA-binding protein HU were found to be substrates of the proteinase, confirming its high substrate specificity. Its molecular mass, N-terminal sequence and enzymatic properties distinguish ECP 32 from any known metalloproteinases of E. coli, and we therefore conclude that it is a new enzyme.

Bacterial protease ECP32 specifically hydrolyzing actin and its effect on cytoskeleton in vivo.

A procedure for isolation of bacterial protease ECP32 yielding 100 microg of the enzyme from 10 liters of the Escherichia coli strain A2 liquid culture has been developed. The procedure includes chromatography, ultrafiltration, and PAGE under non-denaturing conditions. The purified preparation contained about 80% ECP32 and did not exhibit ATPase activity. Polyclonal ECP32-specific antibodies have been produced, and a two-stage procedure for the isolation of protease ECP32 involving affinity chromatography has been elaborated. Microinjection of the purified ECP32 into Amoeba proteus cells caused reversible distortions in amoeba locomotion. The effect was not observed upon inhibition of the protease activity by the ECP32-specific antibodies. The results indicate that bacterial protease ECP32 may be used for the analysis of actin functions in vivo.