Differential Spectroscopy in the Assessment of the Organism Antioxidant Potential (Review).

Methods for determining the oxidant/antioxidant activity of free radicals, antioxidant compounds, and free-radical oxidation products in biological fluids are discussed. General approaches to the analysis of the antioxidant potential of complex natural objects using differential spectroscopy are presented.

Anion exchange resins in phosphate form as versatile carriers for the reactions catalyzed by nucleoside phosphorylases.

In the present work, we suggested anion exchange resins in the phosphate form as a source of phosphate, one of the substrates of the phosphorolysis of uridine, thymidine, and 1-(β-ᴅ-arabinofuranosyl)uracil (Ara-U) catalyzed by recombinant uridine (UP) and thymidine (TP) phosphorylases. α-ᴅ-Pentofuranose-1-phosphates (PF-1Pis) obtained by phosphorolysis were used in the enzymatic synthesis of nucleosides. It was found that phosphorolysis of uridine, thymidine, and Ara-U in the presence of Dowex 1X8 (phosphate; Dowex-Pi) proceeded smoothly in the presence of magnesium cations in water at 20-50 °C for 54-96 h giving rise to quantitative formation of the corresponding pyrimidine bases and PF-1Pis.

The interaction of phospholipase A with oxidized phospholipids at the lipid-water surface with different structural organization.

Phospholipase A (PLA IB) activity towards UV-irradiated (λ=180-400nm) phospholipids in comparison to non-irradiated ones was investigated using phosphatidylcholine (PC) liposomes and mixed micelles of phosphatidylcholine and sodium deoxycholate as a membrane model. PLA activity, determined by spectral changes of hemoglobin (Hb) under the interaction with fatty acids (product of the phospholipolysis), correlated well with the phospholipid peroxidation degree. The present work is the first study that determines the degree of oxidation of non-fragmented OxPCs, on the base of PLA activity.

Prognostic significance of additional cytogenetic aberrations in 733 de novo pediatric 11q23/MLL-rearranged AML patients: results of an international study.

We previously demonstrated that outcome of pediatric 11q23/MLL-rearranged AML depends on the translocation partner (TP). In this multicenter international study on 733 children with 11q23/MLL-rearranged AML, we further analyzed which additional cytogenetic aberrations (ACA) had prognostic significance. ACAs occurred in 344 (47%) of 733 and were associated with unfavorable outcome (5-year overall survival [OS] 47% vs 62%, P < .

Novel prognostic subgroups in childhood 11q23/MLL-rearranged acute myeloid leukemia: results of an international retrospective study.

Translocations involving chromosome 11q23 frequently occur in pediatric acute myeloid leukemia (AML) and are associated with poor prognosis. In most cases, the MLL gene is involved, and more than 50 translocation partners have been described. Clinical outcome data of the 11q23-rearranged subgroups are scarce because most 11q23 series are too small for meaningful analysis of subgroups, although some studies suggest that patients with t(9;11)(p22;q23) have a more favorable prognosis.

Translocation (10;11)(p12;q23) in childhood acute myeloid leukemia: incidence and complex mechanism.

Using both conventional and molecular cytogenetic methods, we found five new cases of t(10;11)(p12;q23). This translocation represented 28% of all cases of childhood AML treated at our center in 2004, and 63% of AML with rearrangements of 11q23. We describe three mechanisms for the translocation.

Dynamics of formation of lysoforms on enzymatic hydrolysis of phosphatidylalkanols.

Hydrolysis of 1,2-dioleoyl-sn-glycero-3-phosphomethanol (DOPM), 1,2-dioleoyl-sn-glycero-3-phosphoethanol (DOPEt), 1,2-dioleoyl-sn-glycero-3-phosphoethyleneglycol (DOPEG), and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) catalyzed by phospholipase A2 (PLA2) from porcine pancreas was studied in single-component and binary model bilayer membranes (liposomes). The presence of anionic phosphatidylalkanols increases the rate of hydrolysis of zwitterionic DOPC in liposomes by the action of PLA2. The rate of formation of lysoforms of anionic ("acidic") lipids at the initial reaction stage in single-component liposomes increased in the following sequence: DOPEG < DOPM < DOPEt (compared with that for the zwitterionic DOPC).

Influence of ethanol and phosphatidylethanol on the activity of pancreatic phospholipase A2.

Hydrolysis of dioleoylphosphatidylethanol (DOPEt) and dioleoylphosphatidylcholine (DOPC) catalyzed by phospholipase A2 (PLA2) from porcine pancreas has been studied in single-component and binary liposomes in the absence and in the presence of ethanol. DOPEt (an anionic phospholipid) was found to increase the rate of hydrolysis of zwitterionic DOPC in liposomes under the action of PLA2.

[Effect of chemical compounds on phospholipase A2 activity].

A simple and convenient method of simultaneous determinations of effects of any set of chemical compounds on enzymatic hydrolysis of phospholipids by using the method of diffusion phospholipase A2 in a lecithin-agarose gel.

[Effects of fatty acid amides on phosphatidylcholine hydrolysis catalyzed by phospholipase A2 in micelles].

The effect of fatty acid amides on the hydrolysis of natural phosphatidylcholine and its semisynthetic analog, dioleoyl phosphatidylcholine, catalyzed by phospholipase A2 in mixed micelles with Triton X-100 has been studied. Palmitoylamide, oleoylamide, and stearoylamide were shown to be the inhibitors of enzymatic phospholipid hydrolysis.

[Complex-formation of phospholipase A2 with fragments of nucleic acids and approaches to its elimination].

Formation of phospholipase A2 stable complexes with nucleic acid fragments was observed upon the isolation of the enzyme from pig pancreas. This complex could be disrupted by neither DNA precipitation with protamine chloride and cetyltrimethylammonium bromide nor chromatography on DEAE-cellulose and CM-cellulose or hydroxyapatite. The treatment of the complexes with 1 M acetic acid followed by gel-chromatography on Sephadex G-75 in 1 M acetic acid resulted in complete separation of active phospholipase A2 from DNA fragments.

[The phospholipase A2 hydrolysis of irradiated lipid membranes].

Phospholipase A2 hydrolysis of dioleoylphosphatidylcholine, dimyristoylphosphatidylcholine or their equimolar mixture with sphingomyelin in liposomes exposed to gamma-radiation has been investigated. Stabilization of the gamma-irradiated lipid bilayer to hydrolysis by sphingomyelin has been shown.

[The resistance of liposomes as potential drug carriers to the action of phospholipase A2].

Stability of liposomes with varied phospholipid (PL) content towards the action of phospholipase A2 (PLA2) was studied in vitro. Liposomes were prepared of phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), and phosphatidylinositol (PI) and their mixtures with sphingomyelin (SM). PC and PG liposomes were also treated with PLA2 in the presence of a number of proteins such as cytochrome c, cytochrome b5, cytochrome P-450, polylysine, and histone H1.

[Lipolysis in model membranes in the presence of positively charged soluble proteins].

Phospholipase A2 hydrolysis of neutral and negatively charged lipid membranes modified by positively charged proteins has been studied using liposomes composed of either dioleoylphosphatidylcholine (DOPC) or dioleoylphosphatidylglycerol (DOPG) alone or their equimolar mixture in the presence of cytochrome c, histone H1, cytochrome b5, and polylysine. Twenty minutes after the reaction had been initiated, DOPC hydrolysis was 58%, while that in the equimolar mixture with DOPG was 35%. DOPG hydrolysis was more complete in binary mixtures of liposomes.

[The use of hemoglobin for determination of phospholipase A2 activity].

A spectrophotometric method is proposed for determining phospholipase A2 activity, which is based on the conversion of hemoglobin into hemichrome under the fatty acid action. The spectral difference between hemoglobin and hemichrome was registered by the difference spectrum with a minimum at 405 nm and a maximum at 423 nm. The absorption value determined as the difference between the spectrum maximum and minimum was proportional to the amount of the fatty acid derived from hydrolysis of phospholipids.

[Study of phospholipase A2 specificity in substrate-containing structures having different supramolecular organization].

The specificity of snake venom phospholipase A2(PLA2) towards a number of phospholipid (PL) substrates, e. g., phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) organized in Triton X-100 mixed micelles, liposomes and proteoliposomes was studied.

[Separation and purification of isoenzymes of Clostridium perfringens phospholipase C].

The procedure for separation and purification of isoenzymes of phospholipase C from Clostridium perfringens (PLC) was developed. The procedure included primary concentration of culture liquid proteins and isoenzyme separtion on DEAE-cellulose during negative sorption of the major isoenzyme. Further purification of the isoenzymes was achieved by (NH4)2SO4 fractionation by Sephadex gel-filtration and isoelectric focusing.

[The actions of low-molecular fragments of substrate and their analogs on the activity of isoenzymes of phospholipase C from Clostridium perfringens].

The interaction of the lecithin molecule fragments and their analogues with phospholipase C Cl. perfringens was studied by gel-diffusion in agarose-lecithin gels. It was found intense inhibition of phospholipase C activity in the presence of cathionic compounds; this phenomenon shows the existence of anionic centre in the active site of enzyme.

[Anionic center of porcine pancreatic phospholipase A2].

The interaction between porcine pancreatic phospholipase A2 and low-molecular fragments of its substrate -- lecithine was studied using gel-diffusion of the enzyme in lecithin-agarose plates. When the inhibitor was added, a decrease in the magnitude of cleared areas (l/l0) around the depots filled with enzyme solution was observed. A marked decrease in l/l0 in the presence of alpha- and beta-glycerophosphates supported the statement that the cathionic center is a part of the enzyme active site SII.