Information methods for model selection in linear mixed effects models with application to HCV data

In this paper, we derive a small sample Akaike information criterion, based on the maximized loglikelihood, and a small sample information criterion based on the maximized restricted loglikelihood in the linear mixed effects model when the covariance matrix of the random effects is known. Small sample corrected information criteria are proposed for a special case of linear mixed effects models, the balanced random-coefficient model, without assuming the random coefficients covariance matrix to be known. A simulation study comparing the derived criteria and several others for model selection in the linear mixed effects models is presented. We illustrate the behavior of the studied information criteria on real data from a study of subjects coinfected with HIV and Hepatitis C virus. Robustness of the criteria, in terms of the error distributed as a mixture of normal distributions, is also studied. Special attention is given to the behavior of the conditional AIC by Vaida and Blanchard (2005). Among the studied criteria, GIC performs best, while cAIC exhibits poor performance. Because of its inferior performance, as demonstrated in this work, we do not recommend its use for model selection in linear mixed effects models.     

Anti-oxidant activity and mechanism of action of trans-resveratrol in different lipid systems

The anti-oxidative properties of trans -resveratrol were studied in the concentration range 0.02–0.20% (8.8 × 10⁻⁴–8.8 × 10⁻³  M ) during autoxidation of pure triacylglycerols of lard (TGL) and of pure triacylglycerols of sunflower oil (TGSO), as well as of commercial sunflower oil at 100 °C. In sunflower oil trans -resveratrol showed no anti-oxidative activity. In pure lipid systems trans -resveratrol considerably retarded the oxidation process, the effect being stronger in the less oxidizable substrate (TGL). The effectiveness (stabilization factor F ), strength (oxidation rate ratio, ORR) and activity ( A = F /ORR) of the different anti-oxidant concentrations were determined. The activity A was found to increase dose dependency as follows: A =3750–15425 for TGL, A =79–207 for TGSO. The participation of trans -resveratrol in the side reactions of inhibited oxidation was discussed.     

One Question,Multiple Answers: Biochemical and Biophysical Screening Methods Retrieve Deviating Fragment Hit Lists

Fragment‐based lead discovery is gaining momentum in drug development. Typically, a hierarchical cascade of several screening techniques is consulted to identify fragment hits which are then analyzed by crystallography. Because crystal structures with bound fragments are essential for the subsequent hit‐to‐lead‐to‐drug optimization, the screening process should distinguish reliably between binders and non‐binders. We therefore investigated whether different screening methods would reveal similar collections of putative binders. First we used a biochemical assay to identify fragments that bind to endothiapepsin, a surrogate for disease‐relevant aspartic proteases. In a comprehensive screening approach, we then evaluated our 361‐entry library by using a reporter‐displacement assay, saturation‐transfer difference NMR, native mass spectrometry, thermophoresis, and a thermal shift assay. While the combined results of these screening methods retrieve 10 of the 11 crystal structures originally predicted by the biochemical assay, the mutual overlap of individual hit lists is surprisingly low, highlighting that each technique operates on different biophysical principles and conditions.     

Antioxidant activity screening of extracts from Sideritis species (Labiatae) grown in Bulgaria

Plant samples from several species and populations of the genus Sideritis (Labiatae) grown in Bulgaria (S scardica, S syriaca and S montana) were extracted with different solvents. Their antioxidant activities were determined by the β‐carotene bleaching test (BCBT), 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH^?) radical scavenging method and static headspace gas chromatography (HS‐GC) and compared with the antioxidant activity of two reference compounds of different polarity, viz butylated hydroxytoluene (BHT) and rosmarinic acid. The pure reference compounds were applied in a ten‐times lower concentration than the plant extracts. The highest antioxidant activity in the BCBT, close to that of BHT, was observed for the more apolar extracts. The inhibitory effect on β‐carotene bleaching of the polar extracts and rosmarinic acid was much lower than that of BHT. The inhibition of hexanal formation in bulk safflower oil by most of S syriaca and S scardica extracts was as effective as BHT but less so than rosmarinic acid. S montana extracts showed weak antioxidant or even pro‐oxidant properties. Extracts from butanol and from ethyl acetate and the total methanol extracts from all Sideritis plants studied showed a strong radical scavenging activity against DPPH^?, close to that of rosmarinic acid. S montana extracts were, as a whole, slightly weaker radical inhibitors than the extracts from the other two species. The antioxidant activity of Sideritis extracts was attributed to the presence of flavonoid and phenylpropanoid glycosides. Copyright © 2003 Society of Chemical Industry     

ABH blood group antigen significance as markers of endothelial differentiation of mesenchymal cells

The expression pattern of A, B and H blood group antigens was evaluated by staining frozen sections with specific monoclonal antibodies developed by us and using the indirect immunoperoxidase method. The expression of blood group antigens was ubiquitously upregulated in the endothelial cells of fetal organs. In the process of their differentiation to endothelial naive embryonic mesenchymal cells expressed cytoplasmic ABH antigens. They were assumed as products of the activation of the respective genes. ABH antigen expression was considered as suggestive evidence for the assumption that blood group antigens could serve as early immunomorphologic markers of endothelial differentiation of mesenchymal cells, thus specifying the location of future blood vessels. Extending the conceptual framework of blood group antigens' significance we consider them as being possibly involved in the process of fetal morphogenesis.     

Natural antioxidants from herbs and spices

There is a growing interest in natural antioxidants found in plants because of the world‐wide trend toward the use of natural additives in food and cosmetics. Herbs and spices are one of the most important targets to search for natural antioxidants from the point of view of safety. This review presents the results on stabilization of lipids and lipid‐containing foods with different herbs and spices (ground materials or extracts) and reports the structure of the main antioxidatively acting compounds isolated from them. The review presents information about the antioxidative effects of rosemary, sage, oregano, thyme, ginger, summer savory, black pepper, red pepper, clove, marjoram, basil, peppermint, spearmint, common balm, fennel, parsley, cinnamon, cumin, nutmeg, garlic, coriander, etc. Among the herbs of the Labiatae family, rosemary has been more extensively studied and its extracts are the first marketed natural antioxidants. Sage and oregano, which belong to the same family, have gained the interest of many research groups as potential antioxidants.     

Adaptive Control of Motion of a Group of Robots Along a Prescribed Trajectory

Optoelectronics, Instrumentation and Data Processing - A control method and software structure for solving the problem of control of motion of a group of robots along a prescribed trajectory with...     

Kinetics of lipid oxidation in the presence of cinnamic acid derivatives

The effects of seven (prenyl‐ and methoxy‐) derivatives of cinnamic acid (0.1 mM) on the kinetics of lipid (sunflower oil triacylglycerols, TGSO) bulk phase oxidation at 80 °C have been compared. Synthesis of prenyl cinnamic acid derivatives: 3‐prenyl‐4‐hydroxy‐cinnamic acid (PHC), 3,5‐diprenyl‐4‐hydroxy‐cinnamic acid (DPHC), 2,2‐di‐methyl‐6‐carboxy‐ethenyl‐2H‐benzopyran (DMCB), 2,2‐dimethyl‐6‐carboxy‐ethenyl‐8‐prenyl‐2H‐benzopyran (DCEPB) present in Brazilian propolis has been performed. The monoprenyl derivative (PHC) has been found to exert a higher antioxidant activity as compared to the diprenyl derivative (DPHC). However, cinnamic acid derivatives DMCB and DCEPB have caused no change in the kinetics of TGSO oxidation. The results obtained have been compared with those on related compounds containing a cinnamic acid moiety as a structural feature, such as 4‐hydroxy‐cinnamic (p‐coumaric), 3‐methoxy‐4‐hydroxy‐cinnamic (ferulic) and 3,5‐dimethoxy‐4‐hydroxy‐cinnamic (sinapic) acids, as well as with data on butylated hydroxytoluene (BHT) and α‐tocopherol (αToc). PHC has shown a stronger antioxidant efficiency than BHT, p‐coumaric and ferulic acid, but a weaker antioxidant efficiency than α‐Toc and sinapic acid. The observed antioxidant effect of DPHC was stronger than that of p‐coumaric and ferulic acids and weaker than that of α‐Toc, BHT and sinapic acid.     

On the participation of fatty alcohols in the autoxidation of lipids

The influence of 1-tetradecanol, 1-hexadecanol, 1-octadecanol and 1-eicosanol in concentrations of 5 to 80 mmol kg^?1 on the autoxidation of various types of lipid systems (sunflower and olive oils, lard, tristearin and olive oil methyl esters) is investigated at 70–135°C. A pro-oxidative effect of the fatty alcohols introduced into the systems is established. The extent of this effect depends on the type and degree of unsaturation in the lipid system, its hydroperoxide content, and the chain length and concentration of the alcohols. A further factor is the valency of the alcohols with which the fatty acids are esterified; thus the pro-oxidative effect of the fatty alcohols is less pronounced with triacyl glycerols than with fatty acid methyl esters given the same oxidation rate. The results obtained are explained on the basis of the theory of a radical chain process of lipid oxidation.     

Classification of Ferrospinel Structures and Textures

The nomenclature and classification of ferrospinel structures and textures are presented. Conditions for their formation are described. In this respect, the classification suggested may be used both as a basis for closer investigation and as a means of obtaining ferrites with the desired structure.