[Preparation and characterization of monoclonal antibodies to the cholera toxin].

Monoclonal antibodies to cholera toxin were obtained. They do not cross-react with the termolabile toxin (LT) of Escherichia coli, ricin, diphtherial toxin, staphylococcus enterotoxins of SEA, SEB, SEI, SEG, or the lethal factor and protective antigen of the anthrax toxin. Pairs of antibodies for the quantitative measurement of the cholera toxin in sandwich enzyme immunoassay (EIA) were selected. The detection limit of the toxin is 0.2 ng/ml for plate EIA and 0.44 ng/ml for microchip EIA. The presence of milk, broth, or surface water in the toxin samples does not reduce the sensitivity of EIA.

Effects of liposomes of different lipid composition on in vitro growth of Mycobacterium tuberculosis H37Rv.

The growth of M. tuberculosis H37RV in culture medium was studied after addition of liposomes from different lipids (phosphatidylcholine, cardiolipin, and glycosphyngolipids). Addition of phosphatidylcholine into culture medium did not modify the growth and multiplication of mycobacteria. Addition of glycosphyngolipids and their mixture with phosphatidylcholine partially inhibited the growth. Addition of cardiolipin inhibited the growth of mycobacteria and even suppressed it, depending on the dose. Presumably, high concentrations of cardiolipin added into the culture medium, can transfer the mycobacteria into an uncultivable state.

Glucosaminylmuramyl dipeptide potentiates the effects of tumor necrosis factor-alpha and cisplatin on transformed cells in vitro.

We studied the effect of combined treatment with cisplatin, glucosaminylmuramyl dipeptide, and TNF-alpha on viability of MCF-7, U-937, B16, and L-929 tumor cells, Ehrlich ascites carcinoma cells, and normal cells (human peripheral blood lymphocytes, peritoneal macrophages, and mouse bone marrow cells). Glucosaminylmuramyl dipeptide was nontoxic for normal and tumor cells, but promoted death of tumor cells after administration in combination with cisplatin and/or TNF-alpha. At the same time, glucosaminylmuramyl dipeptide did not modulate the cytotoxic effect of individual or combined treatment with cisplatin and TNF-alpha on normal cells. Administration of glucosaminylmuramyl dipeptide to cultured MCF-7 cells 20 h before the study increased the potentiating effect of muramyl peptide.

[Role of carbon substrates of culture media on Mycobacterium smegmatis susceptibility to antitubercular agents].

Influence of medium composition on Mycobacterium smegmatis growth and susceptibility to antituberculosis drugs (ATD)--isoniazid and rifabutin--was studied. It was shown that addition of phospholipids (PL) in form of liposomes to meat peptone broth resulted in activation of M. smegmatis growth and decrease of its susceptibility to ATD. Growth characteristics of M. smegmatis and its susceptibility to ATD were studied using variants of modified on source of carbon synthetic medium Sauton as growth substrate. It was revealed that presence of acetate or PL in growth medium results in significant decrease of M. smegmatis susceptibility to isoniazid and rifabutin. It was suggested that this phenomenon is determined by activation of glyoxylate cycle by PL and fatty acids, which, in its turn, can stimulate expression of a number of proteins, including cell membrane pumps excreting antibiotics out of microbial cell.

[Endogenous Tumor necrosis factor alpha unmasks the binding sites for N-acetylglucosaminyl-(beta1-4)-N-acetylmuramyl-alanyl-D-isoglutamine on the surface of melanoma cells]. / Endogennyi faktor nekroza opukholei demaskiruet na poverkhnosti kletok melanomy tsentry sviazyvaniia N-atsetilgliukozaminil-(beta1-4)-N-atsetilmuramoil-alanil-D-izoglutamina.

The surface of the melanoma BRO cells was shown to contain binding sites for N-acetylglucosaminyl-(beta 1-4)-N-acetylmuramyl-alanyl-D-isoglutamine (GMDP). Their number (1500 +/- 200 per cell) and affinity (Kd = 10 +/- +/- 1.2 nM) were determined. The occurrence of these sites was found to correlate with the ability of the melanoma cells to react in vitro with GMDP by increasing the expression of melanoma-associated antigens (MAA). An increased number of the GMDP binding sites (5200 +/- 500 per cell) was observed upon treating the melanoma BRO cells with tumor necrosis factor alpha (TNF-alpha). The mechanism of the TNF-alpha action most likely involves the unmasking of GMDP binding sites, initially expressed on the cell surface, by activating the endogenous protease that hydrolyzes surface proteins, in particular, highly glycosylated LAMP-2 protein exposed on the melanoma cell surface.

Endogenous tumour necrosis factor-alpha sensitise melanoma cells to glucosaminylmuramyl dipeptide.

Flow cytometry was used to demonstrate that cultured human melanoma BRO cells expressed membrane-bound tumour necrosis factor-alpha (TNF-alpha) and were able to release TNF-alpha upon treatment with glucosaminylmuramyl dipeptide (GMDP). The released TNF-alpha was shown to prime melanoma cells, previously unable to respond to GMDP by increasing expression of melanoma-associated antigens, making them sensitive to GMDP treatment.

Albumin-like glycoprotein from human fetal tissue.

Albumin-like glycoprotein (Gp66) with a molecular mass of 66 kDa has been isolated from human fetal tissue by size-exclusion, ion-exchange chromatography and reverse-phase HPLC. Reactivity of Gp66 with antiserum raised against the major protein components fraction of human fetal serum was observed. The N-terminal 35 amino acid residues of Gp66 were identical to human serum albumin. Meanwhile Gp66 differed from albumin by a/ the presence of 3-5 Trp residues instead of 1 according to fluorescence and UV-spectra, b/ the glycosylation pattern: bi-, tri-, and tetraantennary sialooligosaccharides of a complex type were present. Isoelectric focusing revealed 4 isoforms (pI ranging within 4.8 to 5.1) of Gp66. Gp66 (but not asialo-Gp66) was able to inhibit the cytotoxic effect of TNF against the tumor cell line L929. Inhibition of WEHI-3 and L929 tumor cells proliferation by Gp66 was similar to that of albumin.

[Ultrasonic study of the fetal heart in a pregnant woman with antiphospholipid antibodies]. / Ul'trazvukovoe issledovanie serdtsa ploda u beremennoi s nalichiem antitel k fosfolipidam.

Analysis of the findings of ultrasonic examinations of the fetal heart in pregnant women with antibodies to phospholipids has shown changes in this parameter in 42% of the examinees, in 3 cases antenatal fetal death was revealed. The detected changes were of different nature, but in the majority of cases they were of a compensatory type. Marked hypertrophy of the right ventricular myocardium, whose work in the antenatal period is largely responsible for the viability of the fetus, was found.

[Study of the interaction of the monoclonal antibody to human interleukin-2 and its Fab-fragment with synthetic peptides --interleukin-2 fragments by (1)H-NMR]. / Issledovanie metodom (1)H-IaMR vzaimodeistviia monoklonal'nogo antitela k interlekina-2 cheloveka i ego Fab-fragmenta s sinteticheskimi peptidami--fragmentami interleikina-2.

Proton signals for nine synthetic peptide fragments of human interleukin-2 (region 59-78) were assigned for aqueous solutions both of pure peptides and their mixtures with LNKB-2 monoclonal antibody. The nonspecific magnetization transfer (NOE) between the antibody or its Fab-fragment and the peptides was studied upon large excess of free peptide over bound peptide. NOE spectra using modified pulse sequence, enabling to eliminate broad signals and achieve higher (peptide signal)/noise ratio were obtained. The saturation transfer experiments indicated that methyl groups of amino acid residues corresponding to Leu66,70,72, Val69 and Ala73 in interleukin-2 contact with the antibody binding site. Thus, the hydrophobic interactions are of major importance for the LNKB-2-IL-2 peptide complexes. The minimal IL-2 fragment which can still bind to LNKB-2 monoclonal antibody is -Leu70-Asn71-Leu72-.