Ambident reactivity of 5-aminopyrazoles towards donor-acceptor cyclopropanes.

Lewis acid-catalysed reactions of donor-acceptor cyclopropanes with 1,3-disubstituted 5-aminopyrazoles were investigated. Under catalysis with gallium(III) chloride, products of the three-membered ring opening a nucleophilic attack of the exocyclic amino group were obtained in a chemoselective manner. Oppositely, in the presence of scandium(III) triflate, products of either -alkylation or (4)-alkylation, or a mixture of both were formed.

The effect of hypochlorite- and peroxide-induced oxidation of plasminogen on damage to the structure and biological activity.

In this study, we examined for the first time the effect of the HOCl/OCl- and HO-induced oxidation of Glu-plasminogen on damage to its primary structure and the biological activity of plasmin. The consolidated results obtained with the aid of MS/MS, electrophoresis, and colourimetry, demonstrated that none of the oxidised amino acid residues found in the proenzyme treated with 25 μM HOCl/OCl or 100 μM HO were functionally significant for plasminogen. However, the treatment of plasminogen with increasing concentrations of HOCl/OCl from 25 μM to 100 μM or HO from 100 μM to 300 μM promoted a partial loss in the activity of oxidised plasmin.

Donor-Acceptor Cyclopropane Ring Opening with 6-Amino-1,3-dimethyluracil and Its Use in Pyrimido[4,5-]azepines Synthesis.

A scandium trifluoromethanesulfonate-catalyzed reaction of donor-acceptor cyclopropanes with 6-amino-1,3-dimethyluracil was found to proceed as three-membered ring opening via nucleophilic attack of the C(5) atom of an ambident nucleophile serving as an enamine equivalent. It was shown that, under basic conditions, the obtained products underwent cyclization to 6,7-dihydro-1-pyrimido[4,5-]azepine-2,4,8-triones, an interesting subclass of nucleobase analogues.

Noninvasive ultrasound imaging for assessment of intact microstructure of extracellular matrix in tissue engineering.

Development of artificial tissues or organs is one of the actual tasks in regenerative medicine that requires observation and evaluation of intact volume microstructure of tissue engineering products at all stages of their formation, from native donor tissues and decellularized scaffolds to recipient cell migration in the matrix. Unfortunately in practice, methods of vital noninvasive imaging of volume microstructure in matrixes are absent. In this work, we propose a new approach based on high-frequency acoustic microscopy for noninvasive evaluation and visualization of volume microstructure in tissue engineering products.

Ozone-induced damage of fibrinogen molecules: identification of oxidation sites by high-resolution mass spectrometry.

Fibrinogen is highly susceptible to oxidation compared to other plasma proteins. Fibrinogen oxidation damages its structure and affects the protein function. Ozone-induced oxidative modifications of the fibrinogen Aα, Bβ, and γ polypeptide chains upon addition of various amounts of the oxidiser were studied by mass spectrometry.

[Lipid peroxidation and its connection with the change in composition and antioxidant properties of lipids in comatogenic forms of acute viral hepatitis B].

81 patients of acute viral hepatitis B (AVHB) without symptoms of acute hepatic encephalopathy, 39 AVHB patients with such symptoms and 115 age and sex match healthy controls were biochemically and clinically investigated. Besides usual biochemical analyses, some special parameters such as interrelationship between the patterns of lipid peroxidation (LPO) (conjugated dienes and ketodienes and the lipid antioxidant activity) and alterations in lipid composition (content of total lipids, phospholipids and cholesterol) were studied in blood serum. Concentration of LPO products in patients with mild, moderate and severe AVHB without symptoms of encephalopathy was found to be significantly lower than in controls.

[Interactions of inhibitor of free radical reactions and 2-deoxyribosyl macroradicals].

By steric computer modelling of five types of 2-deoxyribosyl radicals and their molecular products generated in DNA by radiation as a result of R + InH = RH + In reaction the displacement of DNA bases (maximum--for C'1 atoms and minimum for C'3 ones) has been determined. Literature data on the DNA decay in the irradiated cells, and in DNA frozen solutions as well as the data on radiolysis of compounds modelling separate DNA fragments allowed to offer a general scheme of the every 2-deoxyribosyl radical transformation and to calculate a balance between the intermediate and final molecular products (processes) of the 2-deoxyribosyl radiolysis. The DNA conformation change due to the 2-deoxyribosyl stereoisomers formation at C'3 and C'4 atoms is discussed as one of the suggested reasons for genetic radiation mutation.