Antioxidant-induced release of calcium in biological membranes

The effect of synthetic (BHT, 2,2,5,7,8-pentamethyl-6-hydroxychroman) and natural (alpha-tocopherol) antioxidants on Ca++-transporting systems was compared in platelets, brain synaptosomes, and skeletal muscle sarcoplasmic reticulum. It was shown that synthetic antioxidants, in contrast to alpha-tocopherol, induced Ca++-release manifested in platelet aggregation, stimulation of 5-hydroxytryptamine release by synaptosomes, synaptosome depolarization and inhibition of Ca++-transport and Ca++-ATPase activity in the sarcoplasmic reticulum. The disturbances of Ca++-homeostasis induced by synthetic antioxidants are considered as molecular mechanisms of complications encountered upon their application.     

Apoptosis and neutrophils in the regulation of Ph-positive myeloid cell proliferation and differentiation ex vivo

Ex vivo proliferation and differentiation of Philadelphia chromosome-positive (Ph⁺) human myeloid cells (Ph+ cells) from chronic myeloid leukemia (CML) proceed via alternation stages of cell proliferation and neutrophil maturation. To regulate them, apoptosis is alternately blocked or induced with the help of neutrophils and expression of bcr/abl, bax, and bcl2. The regulation of apoptosis in main types of Ph⁺ cells depends on the alternation of (1) Ph⁺ cell proliferation and (2) neutrophil maturation and may follow two pathways. One consists in alternating blockages and inductions of apoptosis with initial maturation and subsequent proliferation under alternation stages as (2)-(1)-(2) and has not been described as yet. Neutrophil accumulation blocks apoptosis. As neutrophils are depleted, apoptosis is induced again. Its block accelerates proliferation with a new accumulation of neutrophils, which is followed by regular neutrophil death and a new induction of apoptosis. The way optimizes the proliferation efficiency (P/D index) with a regular alternation of maturation and proliferation, allowing the cycle of proliferation and differentiation to be completed. In another way, the alternation starts with proliferation as (1)-(2)-(1) at a lower neutrophil content) and leads to resistant decrease of the maximal apoptosis level by a factor of 3–8 as compared with (2)-(1)-(2) alternation. A stable block of apoptosis is observed in cells with prolonged stages of proliferation and maturation, leading to an accumulation of blasts and myelocytes with elevated bcr/abl expression and expression of bcl2 > bax. A stable block of apoptosis is associated with CML progression and in Ph⁺ cell lines. Cells follow the first pathway of the apoptotic regulation in chronic-phase CML. Ex vivo cultivation of Ph⁺ cells from individual CML patients was assumed to provide for a more exact diagnosis of the CML phase and optimizing the treatment.     

Interaction between tryptophanyl-tRNA synthetase and tryptophan analogs with modified alpha-amino group

Analogs of L-tryptophane with modified alpha-amino groups (substituted for hydrogen or keto-group, or acylated) are competitive reversible inhibitors of the aminoacylation of tRNNATrp catalyzed by tryptophanyl-tRNA synthetase from beef pancreas. Compounds lacking alpha-amino group are weakly bound to the enzyme, whereas the Ki values for N-acylated L-tryptophane derivates and for beta-indolylpyruvic acid are similar and approximately two orders of magnitude higher than the KM value for L-tryptophane.     

The immune status of children in foci of measles infection studied by an immunoenzyme method

Children immunized with live measles vaccine in the foci of measles infection varying in intensity (1-9 cases per focus) have been subjected by two methods: the hemagglutination inhibition (HAI) test and the enzyme immunoassay (EIA). As shown in this study, in most cases (98% of all blood serum samples) the correlation between the results of the HAI test and EIA is not high (r = 0.5), which is linked with the detection of a wider spectrum of antibodies in EIA. The percentage of seronegative children detected by these two methods was practically the same (4.05 and 4.4, respectively). The analysis of the results obtained in this study indicates that EIA is a more informative and sensitive method, which confirms the effectiveness of its use for the determination of the level of collective immunity.     

Carbohydrates in mammalian tryptophanyl-tRNA synthetase.

Homogeneous preparations of bovine tryptophanyl-tRNA synthetase (EC 6.1.1.2) contain monosaccharides (mannose, fucose, galactose, N-acetylglucosamine) as revealed by liquid chromatography. Their content comprises 2.5-3.0% (w/w) of the enzyme composed of two subunits (60 kDa x 2). The same set of sugars was detected in elastase and CNBr-generated fragments (with molecular masses of approx. 40 kDa and 30 kDa, respectively). It is concluded that bovine tryptophanyl-tRNA synthetase, in addition to being a metallo- and phosphoprotein, is also a glycoprotein.     

Conjugates of Tacrine and Its Cyclic Homologues with <Emphasis Type="Italic">p</Emphasis>-Toluenesulfonamide as Novel Acetylcholinesterase and Butyrylcholinesterase Inhibitors

Using the acylation reaction with tosyl chloride of N-aminopropyl analogues of tacrine and its cyclic homologues with different size of the aliphatic cycle (5–8), we synthesized a number of new derivatives of p-toluenesulfonamide. It is shown that the synthesized hybrid compounds of tacrine and p-toluenesulfonamide are effective inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with the preferential inhibition of BChE. They also displace propidium from the peripheral anionic site of the electric eel AChE (Electrophorus electricus). The characteristics of the efficiency and selectivity of cholinesterase inhibition by the test compounds were confirmed by the results of molecular docking.     

Purification and Investigation of Physicochemical and Regulatory Properties of Homogeneous L-Lactate: Cytochrom <Emphasis Type="Italic">c</Emphasis> Oxidoreductase Obtained from the Nonsulfur Purple Bacterium <Emphasis Type="Italic">Rhodovulum steppense</Emphasis>

L-Lactate: cytochrome c oxidoreductase activity was detected in cells of strain A-20s of the nonsulfur haloalkalophilic purple bacterium Rhodovulum steppense. An electrophoretically homogeneous preparation of the enzyme was obtained by purification. The enzyme had a specific activity of 4.75 U/mg protein, a 81.9-fold purification degree, and a 2.2% yield. The kinetic and physicochemical characteristics were determined. The value of the Michaelis constant with lactate was 15 μM. The temperature optimum for the studied enzyme was 31°C; optimum of pH was 8.2. It was found that the enzyme was a homodimer with a molecular weight of ~140 kDa; the mass of individual subunit was 68 kDa.     

Novel conjugates of tacrine with 1,2,4,-thiadiazole as highly effective cholinesterase inhibitors,blockers of NMDA receptors,and antioxidants

Conjugates of tacrine with 1,2,4-thiadiazole derivatives were synthesized for the first time. Their esterase profile and effects on the key NMDA receptor-binding sites as well as antioxidant activity were investigated. The obtained compounds effectively inhibited cholinesterases (with a predominant effect on butyrylcholinesterase), simultaneously blocked two NMDA receptor-binding sites (allosteric and intrachannel sites, and exhibited a high radical-scavenging activity. Our study shows that the obtained compounds are promising to design drugs for the treatment of Alzheimer’s disease and other multifactorial neurodegenerative diseases.