The synthesis of a new 8-azaprostanoid

The synthesis of a new 8-azaprostanoid is described, using 2-carboethoxycyclopentanone as starting material.     

The synthesis of a new benzothiazine derivative,related to oxicams,synthesized from natural safrole

The synthesis of the new derivatives, 2-methyl-6,7-methylenodioxy-2H-1,2-benzothiazin-3-one-4-(N-phenyl)carboxamide 1,1-dioxide ( 6a ) from natural safrole ( 5 ) is described. The principal feature of this route is brevity and the high overall yield, producing the new analogue in ca. 35% from the natural product.     

Semiempirical calculations on the mechanism of stereoselective NaBH4 reduction of 2-methoxycarbonyl-2-allyl-cyclopentanone

The stereoselective mechanism of reduction of 2-methoxycarbonyl-2-allyl-cyclopentanone with BH₄⁻ was investigated with the AM1 method in the gas phase. Geometries of reactants, transition states, and products were obtained for the reactions conducting to both trans and cis alkoxides. The results suggest that the stereoselectivity is of steric origin. The effect of a chelating Zn²⁺ ion on the reaction stereoselectivity was analyzed.     

Toward a platelet-activating factor pseudoreceptor 2. Three-dimensional semiempirical models for agonist and antagonist binding

Platelet-activating factor (PAF) is an autacoid involved in many inflammatory and allergic diseases. The pathophysiologic effects of PAF result from its interaction with specific cellular membrane receptors, and a number of compounds have been synthesized to antagonize the PAF receptor. Improvements on the affinity of the antagonists for the PAF receptor can be expected from the knowledge of their mode of interaction, but this has been hampered by the absence of structural information on the receptor. As an initial step for the construction of a PAF pseudoreceptor, we proposed in a previous paper a series of molecular probes as representatives of the key amino acids of the active site of the PAF receptor. We present now the development of three-dimensional proposals for pseudoreceptors for PAF by semiempirical molecular modeling. These proposals were identified by means of comparison of the geometric distributions of adequate probes around two proposed bioactive conformers of a model of the natural agonist and around two structurally unrelated potent antagonists of PAF, the hetrazepine WEB 2170 and the diarylic compound L-659,989.     

Cosmological Applications of a Wavelet Analysis on the Sphere

The cosmic microwave background (CMB) is a relic radiation of the Big Bang and as such it contains a wealth of cosmological information. Statistical analyses of the CMB, in conjunction with other cosmological observables, represent some of the most powerful techniques available to cosmologists for placing strong constraints on the cosmological parameters that describe the origin, content and evolution of the Universe. The last decade has witnessed the introduction of wavelet analyses in cosmology and, in particular, their application to the CMB. We review here spherical wavelet analyses of the CMB that test the standard cosmological concordance model. The assumption that the temperature anisotropies of the CMB are a realisation of a statistically isotropic Gaussian random field on the sphere is questioned. Deviations from both statistical isotropy and Gaussianity are detected in the reviewed works, suggesting more exotic cosmological models may be required to explain our Universe. We also review spherical wavelet analyses that independently provide evidence for dark energy, an exotic component of our Universe of which we know very little currently. The effectiveness of accounting correctly for the geometry of the sphere in the wavelet analysis of full-sky CMB data is demonstrated by the highly significant detections of physical processes and effects that are made in these reviewed works.     

Electrospray ionization mass and tandem mass spectra of a series of N-pyrazolylmethyl and N-triazolylmethyl N-phenylpiperazines: new dopaminergic ligands with potential antipsychotic properties

Recently, two analogous series of N-pyrazolylmethyl and N-triazolylmethyl N-phenylpiperazines have been prepared and found to be potential antipsychotic drugs acting as new selective ligands of the dopamine D2 receptor. Herein we report a systematic study of their high-resolution electrospray ionization mass and tandem mass spectra in which the main dissociation routes of their protonated molecules are determined and rationalized. The ESI-MS/MS data is very characteristic for both series allowing straightforward isomeric differentiation. A single and dominant fragment ion for the pyrazole series and four major fragment ions for the triazole series are useful for selective reaction MS monitoring of these potential drugs in biological fluids.     

Computer-assisted enhanced volumetric segmentation magnetic resonance imaging data using a mixture of artificial neural networks

An accurate computer-assisted method able to perform regional segmentation on 3D single modality images and measure its volume is designed using a mixture of unsupervised and supervised artificial neural networks. Firstly, an unsupervised artificial neural network is used to estimate representative textures that appear in the images. The region of interest of the resultant images is selected by means of a multi-layer perceptron after a training using a single sample slice, which contains a central portion of the 3D region of interest.The method was applied to magnetic resonance imaging data collected from an experimental acute inflammatory model (T(2) weighted) and from a clinical study of human Alzheimer's disease (T(1) weighted) to evaluate the proposed method. In the first case, a high correlation and parallelism was registered between the volumetric measurements, of the injured and healthy tissue, by the proposed method with respect to the manual measurements (r = 0.82 and p < 0.05) and to the histopathological studies (r = 0.87 and p < 0.05). The method was also applied to the clinical studies, and similar results were derived of the manual and semi-automatic volumetric measurement of both hippocampus and the corpus callosum (0.95 and 0.88).     

Non-strange vector meson production in K−p interactions at 4.2 GeV/c

The vector meson production, hypercharge exchange reactions K^?p → (φ, ω, ?) Λ and (φ, ?) Σ⁰ are studied at 4.2 GeV/c incident momentum. The data come from a high statistics bubble chamber experiment with a sensitivity of ～ 120 events/μb. Total and differential cross sections are presented. The vector meson density matrix elements and hyperon polarization are investigated as functions of momentum transfer. Amplitude analyses are performed for all five reactions. The results are compared with duality and quark model predictions, as well as used to test current ideas in two-body phenomenology.