Comparison of popliteal lymph node responses in various strains of rats

Outbred (namely Wistar and Sprague-Dawley) and inbred (Wistar-Furth, Lewis, Fisher 344 and Brown-Norway) strains of rats were screened for their responses to reference compounds in the popliteal lymph node (PLN) assay. Streptozotocin and diphenylhydantoin gave positive responses as evidenced by increased weight and cellularity indices in all strains used whereas procainamide, isoniazid and barbital consistently gave negative responses. Although these findings overall are in agreement with previous investigations involving these compounds, the lack of marked interstrain differences in PLN responses argues against a strong immunogenetically controlled mechanism as could be assumed in presumably auto-immune reactions. The question is raised whether drug-induced side-effects predicted by the PLN assay are basically non-autoimmune as suggested by clinical and immunological findings in man.     

Electrochemical method for characterization of graphite-aluminium chloride intercalation compounds

The electrochemical behaviour of different graphites in molten lithium chloroaluminate electrolyte was studied using the potentiodynamic method. The oxidation currents observed at potentials below chlorine evolution are related to the oxidation of graphite during aluminium chloride intercalation.     

Reachability of a Set of Facets for Linear Affine Systems With n-1 Inputs

This note provides new necessary and sufficient conditions for an n-dimensional linear affine system with n-1 inputs to reach an exit facet (or set of exit facets) of a simplex. The conditions reduce the original NP-hard necessary and sufficient conditions to a set of at most n LP problems     

Differentiation between Aspergillus flavus and Aspergillus parasiticus from pure culture and aflatoxin-contaminated grapes using PCR-RFLP analysis of aflR-aflJ intergenic spacer

Aflatoxins (AFs) represent the most important single mycotoxin-related food safety problem in developed and developing countries as they have adverse effects on human and animal health. They are produced mainly by Aspergillus flavus and A. parasiticus. Both species have different aflatoxinogenic profile. In order to distinguish between A. flavus and A. parasiticus, gene-specific primers were designed to target the intergenic spacer (IGS) for the AF biosynthesis genes, aflJ and aflR. Polymerase chain reaction (PCR) products were subjected to restriction endonuclease analysis using BglII to look for restriction fragment length polymorphisms (RFLPs). Our result showed that both species displayed different PCR-based RFLP (PCR-RFLP) profile. PCR products from A. flavus cleaved into 3 fragments of 362, 210, and 102 bp. However, there is only one restriction site for this enzyme in the sequence of A. parasiticus that produced only 2 fragments of 363 and 311 bp. The method was successfully applied to contaminated grapes samples. This approach of differentiating these 2 species would be simpler, less costly, and quicker than conventional sequencing of PCR products and/or morphological identification.     

Interhemispheric connectivity and executive functioning in adults with Tourette syndrome.

The prefrontal cortex (PFC) is relatively smaller, and the corpus callosum (CC) larger, in adults with Tourette syndrome (TS). The authors explored the possible roles of the PFC and the CC in mediating interhemispheric interference and coordination in TS adults. They measured performance on M. Kinsbourne and J. Cook's (1971) verbal-manual interference task and on the bimanual Purdue Pegboard in 38 adults with TS and 34 healthy adults. Compared with controls, TS subjects were impaired on the bimanual Purdue Pegboard. On the dual task, right-hand performance did not differ between groups, but the normally expected left-hand advantage (opposite hemisphere condition) was absent in TS subjects. In the control group only, better left-hand performance accompanied larger PFC volumes but not CC cross-sectional area. PFC dysfunction might have precluded executive control of interference in the TS group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An efficient 3-dim FFT for plane wave electronic structure calculations on massively parallel machines composed of multiprocessor nodes

Three-dimensional Fast Fourier Transforms (FFTs) are the main computational task in plane wave electronic structure calculations. Obtaining a high performance on a large numbers of processors is non-trivial on the latest generation of parallel computers that consist of nodes made up of a shared memory multiprocessors. A non-dogmatic method for obtaining high performance for such 3-dim FFTs in a combined MPI/OpenMP programming paradigm will be presented. Exploiting the peculiarities of plane wave electronic structure calculations, speedups of up to 160 and speeds of up to 130 Gflops were obtained on 256 processors.     

Development of a Hypersensitive Periodate‐Cleavable Amino Acid that is Methionine‐ and Disulfide‐Compatible and its Application in MHC Exchange Reagents for T Cell Characterisation

Incorporation of cleavable linkers into peptides and proteins is of particular value in the study of biological processes. Here we describe the synthesis of a cleavable linker that is hypersensitive to oxidative cleavage as the result of the periodate reactivity of a vicinal amino alcohol moiety. Two strategies directed towards the synthesis of a building block suitable for solid‐phase peptide synthesis were developed: a chemoenzymatic route, involving L ‐threonine aldolase, and an enantioselective chemical route; these led to α,γ‐diamino‐β‐hydroxybutanoic acids in diastereoisomerically mixed and enantiopure forms, respectively. Incorporation of the 1,2‐amino alcohol linker into the backbone of a peptide generated a conditional peptide that was rapidly cleaved at very low concentrations of sodium periodate. This cleavable peptide ligand was applied in the generation of MHC exchange reagents for the detection of antigen‐specific T cells in peripheral blood cells. The extremely low concentration of periodate required to trigger MHC peptide exchange allowed the co‐oxidation of methionine and disulfide residues to be avoided. Conditional MHC reagents hypersensitive to periodate can now be applied without limitations when UV irradiation is undesired or less practical.     

Mapping of elastic modulus at sub-micrometer scale with acoustic contact resonance AFM

Atomic Force Acoustic Microscopy (AFAM) is a powerful near field technique combining the high spatial resolution of Atomic Force Microscope (AFM) with ultrasonic stresses to access mechanical properties of material shallow surfaces (essentially local stiffness magnitudes like Young modulus). In this article, we discuss different experimental set-up and modelling approaches to determine quantitatively the Young modulus of thin films. Static experiments carried-out on dense and nanoporous silica have shown a good agreement with nanoindentation experiments. Stiffness mapping have also been performed on macroporous silica and copper interconnect structures, showing the ability of our set-up to sense different mechanical answers at sub-micrometer scale.     

Direct electrochemical reduction of spinach and desulfovibrio desulfuricans Norway ferredoxins

Electrochemical techniques were used to study the reduction-reoxidation of spinach and Desulfovibrio desulfuricans ferredoxins in the presence of poly- -lysine. A peak corresponding to the reduction of native molecules was detected by differential pulse polarography and voltammetry at the basal-plane pyrolytic graphite electrode. The existence of reduction-reoxidation process was evidenced by cyclic voltammetry. The redox potential values of −0.42±0.01 V (spinach ferredoxin), −0.37±0.01 V (D. desulfuricans ferredoxin I), −0.41±0.01 V (D. desulfuricans ferredoxin II) were obtained. No changes in redox potential values were detected in the pH range 5–9.5. The presence of poly- -lysine promotes the electron transfer between the electrode and the ferredoxin molecules. It is suggested that several factors such as electrostatic interactions and the close environment of clusters can influence the electron transfer rates of heterogeneous exchange between the electrode and the ferredoxin molecules.     

Children's strategy use in computational estimation.

Examined strategic aspects of children's performance in computational estimation. 23 5th-grade children (aged 10 yrs old) were asked to provide estimates of 48 3- by 3-digit addition problems. After each problem, Ss were asked to say how they found the solution. Verbal protocols, speed, and accuracy were collected for each problem so as to identify which computational estimation strategy is used on each trial, and how each strategy is used, selected, and executed. The results show that children used 4 strategies: rounding with decomposition, rounding without decomposition, truncation, and compensation. Strategies appeared to differ in frequency and effectiveness. Finally, children chose strategies in an adaptive way so as to obtain fast and accurate performance. Implications of these findings for understanding children's computational estimation performance and strategies in numerical cognition in general are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)