Antitumor activity of ethanol extract from Hippophae rhamnoides L. leaves towards human acute myeloid leukemia cells in vitro.

We studied the effects of ethanol extract from Hippophae rhamnoides L. leaves on the growth and differentiation of human acute myeloid leukemia cells (KG-1a, HL60, and U937). The extract of Hippophae rhamnoides L. leaves inhibited cell growth depending on the cell strain and extract dose. In a high concentration (100 µg/ml), the extract also exhibited a cytotoxic effect on HL60 cells. Hippophae rhamnoides L. leaves extract did not affect cell differentiation and did not modify the differentiating effect of calcitriol, active vitamin D metabolite. Inhibition of cell proliferation was paralleled by paradoxical accumulation of phase S cells (synthetic phase) with a reciprocal decrease in the count of G1 cells (presynthetic phase). The extract in a concentration of 100 µg/ml induced the appearance of cells with a subdiploid DNA content (sub-G1 phase cells), which indicated induction of apoptosis. The antiproliferative effect of Hippophae rhamnoides L. extract on acute myeloid leukemia cells was at least partially determined by activation of the S phase checkpoint, which probably led to deceleration of the cell cycle and apoptosis induction.

[Influence of wholemeal bread on functional and structure characteristics erythrocytes membrane and lipids oxidation in fraction of microsome of internal organs in rats].

Acute tests in rats showed, that application of wholemeal bread into a standard vivarium ration (40 g per a rat with body weight 180-200 g) drastically impoves structural and functional characteristics of membranes of erlthrocytes and cells of a number of internal organs. Anhibition of peroxide oxidation of biological membranes lipids of internal organs (liver, ridneys, heart, lungs and brain) takes place, as well as impairment of erythrocytes membranes perkeability and increase of their peroxide resistivity.

Alamethicin as a permeabilizing agent for measurements of Ca(2+)-dependent ATPase activity in proteoliposomes, sealed membrane vesicles, and whole cells.

The channel-forming antibiotic peptide alamethicin was used in measurements of Ca-ATPase activity in sarcoplasmic reticulum (SR) vesicles, proteoliposomes containing Ca(2+)-ATPase from SR, and native human platelets. Alamethicin was used as a permeabilizing agent providing for a free access of the whole cells or sealed vesicles interiors for ions, ATP, and other reactants. The experiments were carried out with the use of alamethicin preparations obtained in our laboratory and that purchased from the Upjohn Company (antibiotic U-22,324). A comparative study of the effects of Ca(2+)-ionophore A23187 and alamethicin was performed on native SR vesicles containing Ca(2+)-ATPase molecules with right orientation and SR vesicles treated with cholate in order to randomize Ca(2+)-ATPase molecules orientation in the membrane. It was found out that alamethicin, like A-23187, prevents the ATP-dependent Ca2+ accumulation by the vesicles and therefore activates the Ca(2+)-ATPase. Maximal specific activities of the Ca(2+)-ATPase in native SR vesicles in the presence of either alamethicin, or A23187, or both of them, are equal in all cases to 20 activity units (mumol Pi per min per mg protein). The operative range of alamethicin concentrations is 5-25 micrograms/ml and is a little wider than that for A23187. The ATPase activity of the SR vesicles treated with cholate reached 20 units in the presence of alamethicin while in the presence of A23187 it was only 10 units. These data suggest that alamethicin unlike A23187 allows ATP to reach the ATPase's active centers from the inside of the SR vesicles with 'randomized' membranes, the ATP transport through the membrane not being the rate-limiting stage of ATP hydrolysis. It was shown that diffusion flux of ATP through a BLM in the presence of alamethicin may reach 10% of the flux through the hole without the BLM. With the use of alamethicin it was found out that the quality of randomization of the ATPase molecules orientation in the membrane depends on the proteoliposome preparation technique. The ATP transport through the alamethicin pores makes possible the use of alamethicin in accurate measurements of Ca(2+)-ATPase activity in whole cells. A method was developed for determination of the activity of human platelets was found to be 90-100 nmol Pi per min per mg protein.

[Na,K-ATPase activity in the myocardial sarcolemma in ischemia]. / Na,K-ATP-aznaia aktivnost' v sarkolemme miokarda pri ishemii.

The total time-controlled ischemia (up to 45 min) was studied for its effect on the Na,K-ATPase activity, content of nonesterified fatty acids (NEFA) and intensity of lipid peroxidation (LP) in sarcolemmal (SL) preparations and soluble fractions (SF) from the rat and guinea-pig left ventricles. A strong correlation between Na, K-ATPase inhibition and NEFA accumulation was revealed in the SF. On the contrary, changes in the NEFA content and LP level both in SL and SF did not correlate with a decrease in the enzymic activity. Pretreatment with albumin (0.5 mg/ml) induced equally small increase both in the control and in the ischemic SL preparations. It is suggested that the Na,K-ATPase activity during a short period of myocardial ischemia (up to 45 min) may be due to the NEFA accumulation in the cytosolic and/or extracellular space, but not in SL.

[Antioxidants--stabilizers of the Ca2+ transport enzyme system in sarcoplasmic reticulum membranes in vivo]. / Antioksidanty--stabilizatory fermentoi sistemy transporta Ca2+ v membranakh sarkoplazmaticheskogo retikuluma in vivo.

It has been demonstrated that natural and synthetic antioxidants of different chemical structures (alpha-tocopherol, butylated hydroxytoluene, 2-ethyl-6-methyl-3-hydroxypyridine) were capable of stabilizing enzymatic Ca2+ transport in sarcoplasmic membranes of the heart and skeletal muscles in vivo. Chronic administration of water-soluble antioxidant 2-ethyl-6-methyl-3-hydroxypyridine to young and old rats resulted in the increased rate of Ca2+ transport into sarcoplasmic reticulum vesicles of the heart and skeletal muscle homogenates. Keeping rats on vitamin E-rich diets supplemented with synthetic antioxidant butylated hydroxytoluene led to stabilization of Ca2+-ATPase against thermal denaturation in sarcoplasmic reticular membranes.

[Effect of caffeine on active Ca2+ ion transport in a homogenate of skeletal muscles and myocardium]. / Vliianie kofeina na aktivnyi transport ionov Ca2+ v gomogenate skeletnykh myshts i miokarda.

A Ca2-selective electrode was used to study active transport of Ca2+ by sarcoplasmic reticulum fragments of rabbit skeletal muscle and myocardium homogenates. The specific Ca2+ transport activities (mumol Ca2+/min/mg tissue) are 40 = 60 and 3 = 5 units for fast and slow muscles and the myocardium, respectively. Caffeine (5 mM) exerts a powerful inhibitory influence on Ca2+ transport in skeletal muscle homogenates. For fast muscles, the degree of inhibition exceeds 50%. The rate of Ca2+ transport in the myocardium homogenate increases in the presence of creatine phosphate. The latter produces no effect on Ca2+ transport in skeletal muscle homogenates. The high sensitivity of Ca2 transport to caffeine, a specific blocker of Ca2+ transport to the terminal cisterns of the sarcoplasmic reticulum, suggests that the terminal cisterns, apart from being a reservoir for Ca2+ needed for contraction trigger, may play an essential role in muscle relaxation.

[Conformational mobility and enzymatic activity of Ca2+-ATPase from sarcoplasmic reticulum]. / Konformatsionnaia podvizhnost' i fermentativnaia aktivnost' Ca2+-ATPazy sarkoplazmaticheskogo retikuluma.

Purified preparations of Ca2+-dependent ATPase were lipid-deleted and incorporated into egg lecithin (EL) and dipalmitoyl lecithin (DPL) liposomes. The temperature dependences of the catalytic activity and of molecular mobility of the spin label (N-1-hydroxyl-2,2,6,6-tetramethyl-4-piperidyl) maleimide linked to a highly reactive SH-group in the vicinity of the active center (15-16 A) and of the fatty acid spin probe (6-doxylpalmitate) located in the protein-lipid moiety were compared. The molecular mobility of the spin label was measured by the saturation transfer method; that of the spin probe was estimated from the maximal splitting value. It was found that the catalytic activity of DPL is correlated with the molecular mobility of the hydrophobic part of ATPase, while that of EL with the segment flexibility in the vicinity of the active center.

[Causative factor of Ca2+ transport reduction by sarcoplasmic reticulum fragments under the action of acetylcholine]. / O prichine snizheniia effektivnosti transporta Ca2+ fragmentami sarkuplazmaticheskogo retikuluma pod deistviem atsetilkholina.

The uncoupling of Ca2+ uptake and ATP hydrolysis by acetylcholine (ACh) and choline has been demonstrated on fragmented sarcoplasmic reticulum (FSR) isolated from femoral muscles of Rana ridibunda. The uncoupling depends on the content of oxalate in the incubation medium. An increase in the Ca/ATP ratio caused by serum albumin observed at low oxalate concentrations is indicative of participation of free fatty acids in the uncoupling effect of ACh and choline. The effects of ACh and choline are especially well-pronounced in the case of FSR preparations pretreated with a fatty acid. ACh and choline have no effect on FSR from femoral muscles of Rana temporaria at all oxalate concentrations studied, which may be due to the absence of free fatty acids in these preparations. A pronounced uncoupling effect of ACh is observed after FSR incubation with a fatty acid; the activity of choline is pronounced in a much lesser degree. It is concluded that a decrease in the Ca/ATP ratio in the presence of ACh is due to the enhancement of the uncoupling effects of endogenous free fatty acids.

[Effect of various metabolic poisons on the nature of contraction of the straight muscle of the abdomen of frog]. / Vliianie nekotorykh metabolischeskikh iadov na kharakter sokrashcheniia priamoi myshtsy zhivota liagushki.

A slow decline of responses was obtained after acetylcholine and KCl-stimulation of musculus rectus abdominis of the lake frog in the presence of antymicin A (0.27 mcg/ml). Dinitrophenol (up to 6.7.10(-4) M) as well as antymicin A inhibited the muscle contractility, with the effect being reversible. Muscle contraction ensued the application of dinitrophenol in concentration more than 6.7.10(-4)M. Decurarization ability of dinitrophenol was established. Mechanisms of disruption of the excitation--contraction coupling due to metabolic inhibitors are discussed.