Heuristic programming as an ion generator in mass spectrometry. II—Generation of primary ions from simple cyclic structures

The Ion Generator computer program has now the ability to fragment cyclic structures Examples of mechanisms which are proposed by the program for the fragmentation of simple ring compounds are presented.     

Antiproliferative and antiinflammatory coxib–combretastatin hybrids suppress cell cycle progression and induce apoptosis of MCF7 breast cancer cells

In our study, some newly synthesized aryl-substituted pyrazole derivatives mimicking cis-diphenylethylene scaffold of two apoptotic inducing agents celecoxib and combretastatin A-4 were found to have strong antiproliferative as well as antiinflammatory activities. Among these coxib–combretastatin hybrids, two lead compounds 8 and 6c simultaneously inhibited prostaglandin E2 (PGE2) production in LPS-activated murine macrophage RAW 264.7 cells and suppressed cell cycle progression of MCF7 cells at G2/M or G0/G1 phases, but only compound 8 induced apoptosis via caspase-3 activation. Both the lead compounds showed good docking energies with both protein targets COX-2 and tubulin in the molecule interaction modeling. The cis-diphenylethylene scaffold of celecoxib or combretastatin A-4 as well as functional groups such as the ethyl ester group and the sulfonamide could be considered as potential key features for the dual activity of studied compounds meanwhile the trimethoxybenzene remained the crucial characterization of the newly derived compounds of combretastatins.

     

Potts q-color field theory and scaling random cluster model

We study structural properties of the q-color Potts field theory which, for real values of q, describes the scaling limit of the random cluster model. We show that the number of independent n-point Potts spin correlators coincides with that of independent n-point cluster connectivities and is given by generalized Bell numbers. Only a subset of these spin correlators enters the determination of the Potts magnetic properties for q integer. The structure of the operator product expansion of the spin fields for generic q is also identified. For the two-dimensional case, we analyze the duality relation between spin and kink field correlators, both for the bulk and boundary cases, obtaining in particular a sum rule for the kink-kink elastic scattering amplitudes.     

Glutathione peroxidase inhibitory assay for electrophilic pollutants in diesel exhaust and tobacco smoke

We developed a rapid kinetic bioassay demonstrating the inhibition of glutathione peroxidase 1 (GPx-1) by organic electrophilic pollutants, such as acrolein, crotonaldehyde, and p-benzoquinone, that are frequently found as components of tobacco smoke, diesel exhaust, and other combustion sources. In a complementary approach, we applied a high-resolution proton-transfer reaction time-of-flight mass spectrometer to monitor in real-time the generation of electrophilic volatile carbonyls in cigarette smoke. The new bioassay uses the important antioxidant selenoenzyme GPx-1, immobilized to 96-well microtiter plates, as a probe. The selenocysteine bearing subunits of the enzyme’s catalytic site are viewed as cysteine analogues and are vulnerable to electrophilic attack by compounds with conjugated carbonyl systems. The immobilization of GPx-1 to microtiter plate wells enabled facile removal of excess reactive inhibitory compounds after incubation with electrophilic chemicals or aqueous extracts of air samples derived from different sources. The inhibitory response of cigarette smoke and diesel exhaust particle extracts were compared with chemical standards of a group of electrophilic carbonyls and the arylating p-benzoquinone. GPx-1 activity was directly inactivated by millimolar concentrations of highly reactive electrophilic chemicals (including acrolein, glyoxal, methylglyoxal, and p-benzoquinone) and extracts of diesel and cigarette smoke. We conclude that the potential of air pollutant components to generate oxidative stress may be, in part, a result of electrophile-derived covalent modifications of enzymes involved in the cytosolic antioxidant defense.     

Shrinkage stress and mechanical properties of photoactivated composite resin using the argon ion laser

The objective of this study was to verify the influence of photoactivation with the argon ion laser on shrinkage stress (SS), followed by evaluation of Vickers microhardness (VM), percentage of maximum hardness (PMH), flexural strength (FS), and flexural modulus (FM) of a composite resin. The study groups were: L1-laser at 200 mW for 10 seconds; L2-laser at 200 mW for 20 seconds; L3-laser at 250 mW for 10 seconds; L4-laser at 250 mW for 20 seconds; H-halogen light at 275 mW for 20 seconds. Data were analyzed by ANOVA/Tukey’s test (α=5%). The values of SS (MPa) were statistically lower for the group L3 (1.3)c, followed by groups L1 (2.7)b, L4 (3.4)a, b, L2 (3.7)a, and H (4.5)a. There was no difference in the values of VM when the same time of photoactivation was used, with respective values being L1=70.1a, L2=78.1b, L3=69.9a, L4=78.1b and H=79.9b. All groups showed a PMH of at least 80%. Only the group L1 showed differences in FS (MPa) and FM (GPa), the respective values of 86.2 and 5.4 being lower. Therefore, the use of argon ion laser had influenced the composite resin polymerization. The L3 group presented adequate mechanical properties and minimum SS, reducing the clinical working time for photoactivation of restorations with the tested resin by 50%.     

Heat of formation of La4Bi3 and LaBi compounds

In the LaBi system the formation heats were measured using a direct isoperibol calorimeter. The following values were found:

     

Deuterium isotope effect in l(+)-glutamic acid hydrochloride

A study of the effects of deuterium substitution in l(+)-glutamic acid hydrochloride is described. Solid state vibrational spectra depicting band shifts resulting from deuterium indicate that interatomic bond distances remain virtually unchanged. The cell volume expands only 0.05% upon deuteration, while the macroscopic linear and nonlinear polarizabilities are unaffected. The optical nonlinearity is therefore ascribed to the electronic nature of the hydrogen bonds.