Effects of acute gamma-irradiation on extracellular adenine nucleotide hydrolysis in developing rat brain

Cell membrane is highly sensitive to irradiation which, acting directly or indirectly, may disturb functions of constitutive proteins including membrane enzymes. Plasma membrane surface-located enzyme chain of ecto-nucleotide triphospho diphosphohydrolases (NTPDases) and 5′-nucleotidase are involved in termination of cell purinergic signalization by hydrolyzing extracellular, excitatory adenosine triphosphate (ATP), as well as nucleotide di-, and mono-phosphate (ADP and AMP) to neuroprotective adenosine. Extracellular ATP, ADP, and AMP hydrolyzes were examined in purified synaptic plasma membranes after whole-body acute irradiation. All measurements were done 24 h after irradiation of developing (15-, 30-day-old) and adult (90-day-old) rats with low (50 cGy) and high (2 Gy) dose of gamma-rays. Both, high and low doses inhibited nucleotide hydrolyses in 15-day-old rats; in 30-day-old rats low dose of radiation inhibited ADP and AMP hydrolyses while high dose inhibited only ATP hydrolyse. In adult rats high dose induced no effects, while low dose stimulated nucleotides hydrolyses. According to obtained results it was concluded that ecto-nucleotidases of young rats are more sensitive to irradiation, since even low dose induces inhibition of ecto-nucleotidases activities. Ionizing radiation, by decreasing brain nucleotide hydrolyses in developing rats, induces accumulation of ATP and decreases production of adenosine in synaptic cleft which could be neurocytotoxic. On the contrary, in adult rats low dose of radiation stimulates NTPDase and 5′-nucleotidase activity and protective adenosine production which indicates protective and adaptive mechanisms developed in adult brain neuronal cells. The article is published in the original.     

On minimizing pattern splitting in multi-track string matching

Given a pattern string P=p₁p₂p_m and K parallel text strings over an integer alphabet Σ, our task is to find the smallest integer κ>0 such that P can be split into κ pieces P=P¹…P^κ, where each Pⁱ has an occurrence in some text track T^k_i and these partial occurrences retain the order. We study some variations of this minimum splitting problem, such as splittings with limited gaps and transposition invariance, and show how to use sparse dynamic programming to solve the variations efficiently. In particular, we show that the minimum splitting problem can be interpreted as a shortest path problem on line segments.     

Synthesis, spectroscopy, X-ray structure and redox behaviors of 4-(N-R-salicylideneimine)-2,6-diphenylphenols

A series of sterically hindered 4-(N-R-salicylaldimine)-2,6-diphenylphenols (X), where R=H (1), 3-CH3 (2), 5-CH3 (3), 3-OCH3 (4), 4-OCH3 (5), 5-OCH3 (6), 3-tBu (7), 5-tBu (8), 3,5-tBu2(9) and 5,6-benzo(10), were synthesized and their structure as well as redox behavior studied by analytical, spectroscopic [1H, (13C) NMR, IR, UV-vis and mass spectrometry] and cyclic voltammetric (CV) techniques. Single crystal X-ray diffraction studies of 7 evidenced its existence as non-planar enol-imine tautomer structure, in which the phenol ring of the molecule is twisted around C-N single bond by 21.5(2) degrees. The packing structure of 7 is stabilized by C-H...pi(Ph) and O...O and C...O intermolecular short contact interactions. The CV of X display rate is dependent on irreversible and quasi-reversible redox waves in the anodic and cathodic regions due to oxidation and reduction of phenolic and iminic groups, respectively. As evidenced by ESR and UV-vis study, chemical oxidation of X by PbO2 and (NH4)2Ce(NO3)6 in MeCN and CHCl3 generates stable phenoxyl radicals [(g approximately 2.005 and lambda approximately 450 nm (1600-8200 M(-1) cm(-1))].     

The Cycle Switching Graph of the Steiner Triple Systems of Order 19 is Connected

Switching is a local transformation that when applied to a combinatorial object gives another object with the same parameters. It is here shown that the cycle switching graph of the 11 084 874 829 isomorphism classes of Steiner triple systems of order 19 as well as the cycle switching graph of the 1 348 410 350 618 155 344 199 680 000 labeled such designs are connected. In addition to giving an understanding of the multitude of Steiner triple systems—at least for order 19 but perhaps also generally—this work also presents an algorithm for testing connectedness of large implicit graphs and brings forward a benchmark instance for such algorithms.     

Leptonic decay constants of Ds and Bs mesons at finite temperature

In the present work, D _s and B _s meson parameters are investigated in the framework of thermal QCD sum rules. The temperature dependences of the mass and the leptonic decay constants are investigated by using Borel transform sum rules and Hilbert moment sum rules. To increase the sensitivity, the vacuum contributions are subtracted from the thermal expressions and the temperature dependences of the leptonic decay constants and meson masses are studied.     

Solution properties of poly(dialkyl-cyclohexyl) itaconates

Di(methyl-), di(ethyl-) and di(propylcyclohexyl) esters of itaconic acid were polymerized radically in bulk. The products were characterized in solution, then fractionated and the limiting viscosity number/molecular weight relations established for toluene at 25°. From extrapolations to θ-conditions, a set of σ-values from 2.75 to about 2.90 was obtained and compared with published results for poly(dicyclohexyl itaconate) [1], the first member of this polymer homologous series. The non-uniform change of unperturbed dimensions and other thermodynamic parameters are discussed in terms of chemical composition and constitution of the monomer residues.     

On the enhancement of the recoilless fraction in restricted geometries

The enhancement of recoilless fraction (f factor) in restricted geometries is studied. The experiments were carried out using the¹¹⁹Sn resonance in SnCl₄ molecules trapped in porous glass. A theoretical approach to explain the increase of thef factor is presented.     

Thermogravimetric characterisation of poly(methyl methacrylate) photopolymerised by colloidal cadmium sulphide

The thermal stability of poly(methyl methacrylate) (PMMA) photopolymerised using colloidal cadmium sulphide as the photoinitiator was studied by thermogravimetry (TG) and differential TG (DTG).The thermal stability of the CdS initiated PMMA was greater than that of conventional radically polymerised PMMA and approached that of anionically prepared PMMA. The DTG curve of the CdS initiated PMMA was a composite of four peaks, three of which correspond to the three peaks observed in the DTG curve of standard radically prepared PMMA. It is suggested that the additional peak arises from a new mode of depolymerisation initiation, that is, from chain end unsaturation introduced into the polymer chain during polymerisation initiation with the colloidal CdS.     

Synthesis and solution properties of poly(diphenyl itaconate)

Solid diphenyl itaconate monomer was obtained by esterification in the presence of diphosphorus pentoxide and polymerized in bulk with AIBN as initiator. The non-film forming polymer powder was characterized by fractionation, viscosity measurements, light scattering and other techniques. The relation [n] = 3·6 × 10^?3$\text{M}$^0·70_w, obtained for toluene at 25° was extrapolated to θ-conditions by various procedures: the σ-value of 2·60 for unperturbed dimensions indicates a less pronounced influence of phenyl compared with other C₆ hydrocarbon substitutes.     

Abstract Elliptic Equations with Integral Boundary Conditons

This paper focuses on nonlocal integral boundary value problems for elliptic differential-operator equations. Here given conditions guarantee that maximal regularity and Fredholmness in $L_{p}$ spaces. These results are applied to the Cauchy problem for abstract parabolic equations, its infinite systems and boundary value problems for anisotropic partial differential equations in mixed $L_{\mathbf{p}}$ norm.