The Concept of Folic Acid in Health and Disease

Folates have a pterine core structure and high metabolic activity due to their ability to accept electrons and react with O-, S-, N-, C-bounds. Folates play a role as cofactors in essential one-carbon pathways donating methyl-groups to choline phospholipids, creatine, epinephrine, DNA. Compounds similar to folates are ubiquitous and have been found in different animals, plants, and microorganisms. Folates enter the body from the diet and are also synthesized by intestinal bacteria with consequent adsorption from the colon. Three types of folate and antifolate cellular transporters have been found, differing in tissue localization, substrate affinity, type of transferring, and optimal pH for function. Laboratory criteria of folate deficiency are accepted by WHO. Severe folate deficiencies, manifesting in early life, are seen in hereditary folate malabsorption and cerebral folate deficiency. Acquired folate deficiency is quite common and is associated with poor diet and malabsorption, alcohol consumption, obesity, and kidney failure. Given the observational data that folates have a protective effect against neural tube defects, ischemic events, and cancer, food folic acid fortification was introduced in many countries. However, high physiological folate concentrations and folate overload may increase the risk of impaired brain development in embryogenesis and possess a growth advantage for precancerous altered cells.     

Study of the fast dynamics of domain walls in ferrite-garnet films in the presence of large in-plane fields

The dynamics of domain walls in ferrite-garnet films with orientation (111) was investigated by twofold digital high-speed photography. The experiments were performed in the presence of an in-plane magnetic field comparable to the anisotropy field of the samples.     

Regularities of the sorption of cycloalkenyl-substituted thiophenes and 2,2′-bithiophenes from water-acetonitrile solutions on hexadecyl silica gel under conditions of high-performance liquid chromatography

Regularities of the sorption of newly synthesized cycloalkenyl-substituted thiophenes and 2,2′-bithiophenes from water-acetonitrile solutions of different compositions on hexadecyl silica gel are investigated by high-performance liquid chromatography (HPLC). The retention factors and Henry constants of adsorption of these substances are determined. We discuss the effect of the molecular structure of the investigated heterocycles, and the nature and positions of the substituents, on the sorption. The equilibrium constants for the quasi-chemical reactions of sorption of the investigated compounds at the interface, and their solvation in a multicomponent bulk solution, are calculated using the Lanin-Nikitin equation. Based on the obtained results, we suggest that structural self-organization in the bulk solution and at the interface with the hydrophobic surface of hexadecyl silica gel plays an important part in the sorption of cycloalkenylsubstituted thiophenes and 2,2′-bithiophenes from multicomponent solutions.     

Reactive diffusion in Sc/Si multilayer X-ray mirrors with CrB2 barrier layers

Processes undergoing in Sc/Si multilayer X-ray mirrors (MXMs) with periods of ∼27 nm and barrier layers of CrB₂0.3- and 0.7-nm thick within the temperature range of 420–780 K were studied by methods of small-angle X-ray reflectivity (λ=0.154 nm) and cross-sectional transmission electron microscopy. All layers with the exception of Sc ones are amorphous. Barrier layers are stable at least up to a temperature of 625 K and double the activation energy of diffusional intermixing at moderate temperatures. Introduction of barriers improves the thermal stability of Sc/Si MXMs at least by 80 degrees. Diffusion of Si atoms through barrier layers into Sc layers with formation of silicides was shown to be the main degradation mechanism of MXMs. A comparison of the stability for Sc/Si MXMs with different barriers published in the literature is conducted. The ways of further improvement of barrier properties are discussed.     

Synthesis of oligosaccharide fragments of the Streptococcus pneumoniae type 14 capsular polysaccharide and their neoglycoconjugates with bovine serum albumin

2-Aminoethyl glycosides of tetra-, hexa- and octasaccharide fragments of the bacteria Streptococcus pneumoniae type 14 capsular polysaccharide were synthesized within a project directed to the development of pneumococcal conjugated vaccine based on synthetic carbohydrate ligands. Squarate method was used to obtain neoglycoconjugates of the synthesized oligosaccharides with bovine serum albumin.     

Laws of sorption of some aromatic heterocycles from solutions on nanoporous supercrosslinked polystyrene

Principles of the sorption of 5-tetrazole, 1,3,4-oxadiazole, and 1,2,4,5-tetrazine derivatives from solutions of various composition on nanoporous supercrosslinked polystyrene were studied by high performance liquid chromatography. The influence of the nature of heteroatom on the sorption of these heterocycles was demonstrated. The role of different types of intermolecular interactions in the sorption of the studied substances from solutions on nanoporous supercrosslinked polystyrene in quasi-normal phase and reverse phase liquid chromatography are discussed.     

GRAPH-topological study of adamantanes

Topological characteristics of some structural analogs of adamantanes are calculated. Correlations are studied between the Wiener indices and the experimental chromato graphic retention indices as well as the calculated molecular volumes, hydration energies, and distribution coefficients in an n-octanol water system for the title compounds. Translated from Zhurnal Strukturnoi Khimii, Vol. 41, No. 4, pp. 805-812, July-August, 2000.     

Correlation between the structure and chromatographic retention of some azole derivatives

The chromatographic retention of nitrogen-containing heterocycles was studied in relation to their structure. The role of the type and position of the substituents and functional groups in the chromatographic behavior of these compounds was demonstrated. THe separation in a selected chromatographic system was studied in relation to the dipole moment of the sorbates. Original Russian Text S.V. Kurbatova, O.V. Parshikova, Z.P. Belousova, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 4, pp. 614–620.