Simulation studies for gamma ray shielding properties of Halloysite nanotubes using MCNP-5 code.

Halloysite clay is a mineral found in natural and it has many applications in chemistry (for catalytic and extraction) and also in the medical field (for drugs delivery), so it is important to study the shielding properties of natural and modified nanotube Halloysite. The mass attenuation coefficient was simulated for natural Halloysite clay mineral and four others modified halloysite nanotubes using MCNP 5 code for incident gamma ray energies between 0.015 and 15 MeV. The mass attenuation coefficient was also calculated using the XCOM database for studied samples in the same energy range. The results obtained by the MCNP simulation were close to those obtained by XCOM calculation. Moreover, other shielding properties that described the interaction of incident gamma rays with Halloysite composites, such as the HVL, MFP, Zeff, and Neff were calculated using the simulated µm for gamma rays between 0.015 and 15 MeV.

The potential beneficial role of isoflavones in type 2 diabetes mellitus.

Diabetes is a chronic global disease afflicting a substantial number of people worldwide. Different mechanisms have been highlighted in the progression of this disease such as dysfunction of pancreatic ß-cells, insulin resistance, elevated levels of free fatty acids which result in overproduction of reactive oxygen species, as well as pancreatic ß-cell failure and apoptosis. Isoflavones, are polyphenolic phytochemicals found in most leguminous plants, and have been identified as potentially useful antidiabetic agents. The pleiotropic effects of isoflavones include the targeting of numerous cell signaling pathways involved in the pathogenesis of diabetes. Several observational studies have supported the direct relationship between isoflavones intake and a lowered risk of diabetes. The aim of this review was to summarize relevant findings on the effects of isoflavone intake and risk of type II diabetes mellitus (T2DM), and to highlight some of the possible anti-diabetic molecular mechanisms of these polyphenols. Despite the promising therapeutic effects of isoflavones to moderate risk of T2DM, the underlying mechanisms for their preventive effects are still largely unknown. The acceptable human dosage levels of these polyphenols remain a debatable topic as these have a profound influence on the observed benefits. Considerable numbers of well-controlled, long-term human clinical studies of these phytochemicals are highly recommended. Furthermore, combinations of isoflavones and their derivatives in combination with other naturally isolated compounds, and perhaps even those drugs currently used therapeutically to control diabetes mellitus in clinical practice, may be worth exploring in the future.

Finding intermediates in the O2 activation pathways of non-heme iron oxygenases.

Intermediates in the reaction cycle of an oxygenase are usually very informative with respect to the chemical mechanism of O 2 activation and insertion. However, detection of these intermediates is often complicated by their short lifetime and the regulatory mechanism of the enzyme designed to ensure specificity. Here, the methods used to detect the intermediates in an extradiol dioxygenase, a Rieske cis-dihydrodiol dioxygenase, and soluble methane monooxygenase are discussed. The methods include the use of alternative, chromophoric substrates, mutagenesis of active site catalytic residues, forced changes in substrate binding order, control of reaction rates using regulatory proteins, and initialization of catalysis in crystallo.

Mechanism-based competitive inhibitors of glyoxalase I: intracellular delivery, in vitro antitumor activities, and stabilities in human serum and mouse serum.

S-(N-Aryl-N-hydroxycarbamoyl)glutathione derivatives (GSC(O)N(OH)C6H4X, where GS = glutathionyl and X = H (1), Cl (2), Br (3)) have been proposed as possible anticancer agents, because of their ability to strongly inhibit the methylglyoxal-detoxifying enzyme glyoxalase I. In order to test this hypothesis, the in vitro antitumor activities of these compounds and their [glycyl,glutamyl] diethyl ester prodrug forms (1(Et)2-3(Et)2) have been examined. All three diethyl esters inhibit the growth of L1210 murine leukemia and B16 melanotic melanoma in culture, with GI50 values in the micromolar concentration range. Cell permeability studies with L1210 cells indicate that growth inhibition is associated with rapid diffusion of the diethyl esters into the cells, followed by enzymatic hydrolysis of the ethyl ester functions to give the inhibitory diacids. In contrast, the corresponding diacids neither readily diffuse into nor significantly inhibit the growth of these cells. Consistent with the hypothesis that cell growth inhibition is due to competitive inhibition of glyoxalase I, preincubation of L1210 cells with 2(Et)2 increases the sensitivity of these cells to the inhibitory effects of exogenous methylglyoxal. Compound 2(Et)2 is much less toxic to nonproliferating murine splenic lymphocytes, possibly reflecting reduced sensitivity to methylglyoxal and/or reduced chemical stability of the diacid inside these cells. Finally, a plasma esterase-deficient murine model has been identified that should allow in vivo testing of the diethyl esters.

[Instrumental studies of motor function using "Stabilotest" and "Ataxitest" devices in preschool children]. / Instrumental'noe issledovanie dvigatel'nykh funktsii s pomoshch'iu priborov "Stabilotest" i "Ataksitest" u detei doshkol'nogo vozrasta.

The paper describes devices used to examine motor functions in preschool children, methods of examinations and presents their results. Instrumental indices of the development of large and small motility in preschool children and objective criteria for the efficiency of stimulant therapy are proposed. It is shown that the devices for examination of motor functions may be successfully used to train coordination functions of a child and to correct static motor and ocular motor performance.