جستجوی مقالات مرتبط با کلیدواژه "halogen" در نشریات گروه "پزشکی"

Purine nucleoside phosphorylase (PNP) is one of the major enzymes in the purine salvage pathway. It is responsible for the elevation of deoxyguanosine, and thus considered as the potent target in T-cell lymphoma. The present study examined acyclovir, reported as a low-affinity PNP inhibitor, for the rational design of new acyclovir derivatives by incorporating halogens, hydroxyl, and bulky amino groups. The molecular actions of designed derivatives were investigated by employing density functional theory, molecular docking, and binding energy calculations. The results revealed that the newly designed compounds were highly stable and showed more affinity to PNP than the parent compound, acyclovir. The quantum mechanics and molecular docking studies suggested that modification of side chains with bulky polar groups provided better binding affinities than substitutions with halogens. The resultant derivatives have strong polar interactions like His257 and Tyr88. Furthermore, the designed derivatives were within the ideal range of ADMET (absorption, distribution, metabolism, elimination, and toxicity) analysis. Considering that, these findings recommend further validation of designed acyclovir derivatives in wet lab confirmatory analysis with the emphasis on the further improvements in the treatment of T-cell-mediated diseases.

Improvements in the two-step synthesis of 1,1,1,3,3,3-hexafluoro-2- (fluoromehoxy)propane (Sevoflurane) that result in the product cost reduction, safety level enhancement and positive environmental impacts are described. This process consists of chloromethylation reaction of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) followed by a halogen-exchange fluorination. This is the first synthesis of Sevoflurane in Iran which was successfully scaled up. During this work, several improvements have been achieved by optimization of the reaction time, the amount of consumed starting materials and solvents and work up procedure while keeping the yield and purity intact. The reaction time of the first step (24 h) was diminished to 4 h. 19F NMR spectroscopy was used to investigate the rate of the reaction in the first step and to evaluate the influence of different parameters mentioned on the achieved improvements.

The degree of polymerization depends on the type of light-curing unit. The aim of this study was to compare the hardness of composite resin cured by LED and Halogen light curing units. In this experimental study, 20 cylindrical samples of Tetric Ceram composite were prepared. Half of them were cured with Ultralume 2 LED and the other half with Astralis 7 Halogen light curing unit. In the depths of 0,1,2 and 3 mm from surface, one point in peripheral and one point in central portion were marked, then the hardness of these points was measured by Vickers test. The data was analyzed by a pvalue less than 0.05 considered as significant. The mean hardness of samples cured by LED was more than halogen group in different depths and this difference was statistically significant in peripheral points (p=.048) but this was not significant in central points (p=0.644). The mean hardness in both groups had a decreasing trend from surface to the deep parts in central and peripheral parts and this was more in the central parts. Composites cured by LED light curing unit showed more hardness in similar depths, besides the hardness of composites in central parts is more than the peripheral ones in both groups.