Lisuride prevents learning and memory impairment and attenuates the increase in extracellular dopamine induced by transient global cerebral ischemia in rats

In this experiment, we tested the efficacy of neuroprotection with lisuride, a dopamine agonist, using the 4-vessel occlusion rat model. Functional improvement was evaluated with two behavior tests exploring learning and memorization capacity in the rat, the Morris water maze and the 14-unit T-maze, 18 days after ischemia. Extracellular dopamine levels during ischemia were determined in search of a possible neuroprotection mechanism. Dopamine and its metabolites, DOPAC and HVA, as well as the serotonin metabolite, 5-HIAA, were assayed with HPLC-EC, in striatal extracellular fluid obtained by in vivo microdialysis in the awake rat. Lisuride was administered at a total dose of 10 ng by continuous intrastriatal infusion or at the dose of 0.5 mg/kg by i.p. infusion, 160 minutes before onset of ischemia for the neurochemical study and at the dose of 0.5 mg/kg via i.p. infusion, 1 hour before occlusion of the carotid arteries, for the behavior tests. Behavioral testing showed significantly better recovery in both sets of behavioral tests, with more pronounced positive results with the 14-unit T-maze, in comparison with the saline-treated animals. Microdialysis confirmed a significant attenuation of the ischemia-induced dopamine surge, whatever the mode of administration, compared with saline-treated animals. These results show that lisuride offers significant neuroprotection from the effect of experimental transient global forebrain cerebral ischemia in the rat; the mechanism would imply, at least in part, reduced levels of extracellular dopamine.     

Epidemiological study of latent and recent infection by Toxoplasma gondii in pregnant women from a regional population in the U.K

The last two amino acids in the nascent peptide influence translation termination in E. coli (Mottagui-Tabar et al., 1994; Bj?rnsson et al., 1996). We have compared the effects on termination in Escherichia coli, Bacillus subtilis and Salmonella typhimurium obtained by varying the -1 and -2 codons upstream of the weak UGAA stop signal. The peptide effect from the penultimate amino acid on translation termination in B. subtilis is similar to that seen in E. coli (with 66.5% RF-2 amino acid sequence similarity), whereas the influence in S. typhimurium (with 95.3% similarity to E. coli) is weaker. The effect of changing the -1 codon (P-site) is weaker in S. typhimurium as compared to those in E. coli and B. subtilis. RF-2s from E. coli and S. typhimurium have a threonine or alanine at position 246, respectively. This amino acid exchange in RF-2 can explain the difference in efficiency and toxicity during overexpression when E. coli and S. typhimurium are compared (Uno et al., 1996). However, B. subtilis RF-2 also has an alanine at that position, yet the sensitivity to the nascent peptide is similar to that in E. coli. Thus, the amino acid difference at position 246 in the RF-2 sequences cannot explain why termination in E. coli and B. subtilis is similar in peptide sensitivity while being different from that in S. typhimurium. Sequence alignments of RF-2 from the three bacteria show other regions of the molecule that could be involved in the functional interactions with the C-terminal end of the nascent peptide.     

Constitutive model of the TWIP effect in a polycrystalline high manganese content austenitic steel

The TEM study of our steel with a high manganese content reveals that mechanical twining (TWIP effect) occurs during the deformation at room temperature. Microtwins are organised into parallel stacks and two systems are sequentially activated in each grain. They participate to the deformation and they are strong obstacles for the dislocations and for other twins, leading to the decrease of the effective grain size. Thus, TWIP provides our alloy a very good ductility and a high hardening rate. Our constitutive modelling deduced from a model proposed by Bouaziz and Guelton [4] integrates this typical organisation of microtwins. Twinning is quantified in each grain by the partial volume fraction of twins in each system. A nucleation law for the microtwins is introduced which depends on the local stress and the stress relaxation due to pre‐existing twins. The flow stress is deduced from the dislocation density, which evolves with the dynamical recovery and the decrease of the mean free path (MFP). The MFP takes into account the grain and twin boundaries and the forest dislocations. The strain is calculated by adding the contributions of dislocation glide and twinning accounting the orientation of the grain. To treat the polycristal, the behaviours of different grain orientations are mixed by assuming at each strain step that the increment of elastic energy stored is the same in each grain. The model was successfully applied to describe the mechanical properties of our alloy, for two different grain sizes. Some microstructural parameters are yet fitted. This leads to an insufficient prediction of the evolution of the microstructure. In further developments, we expect to introduce numerical simulation results on local characteristics of microtwins (thickness, critical resolved shear stress for twinning) and experimental results on the rate of twin nucleation.     

Kinetics of chlorination and carbochlorination of molybdenum trioxide

Kinetics of chlorination of MoO₃ with Cl₂-air, Cl₂-N₂, and Cl₂-CO-N₂ gas mixtures have been studied by nonisothermal and isothermal thermogravimetric measurements, between ambient temperature and 900 °C. Between 500 °C and 700 °C, the chlorination reaction of MoO₃ with Cl₂-N₂ gas mixture has an apparent activation energy of about 165 kJ/mole, reflecting that a chemical reaction is the rate-controlling step. The reaction order with respect to Cl₂ partial pressure is about 0.75. The apparent activation energy for carbochlorination with Cl₂-CO-N₂ gas mixture is about 83 kJ/mole, between 400 °C and 650 °C. The carbochlorination of MoO₃ was controlled by the chemical reaction, probably affected by the pore diffusion regime. The maximum reaction rate is obtained by using a Cl₂-CO-N₂ gas mixture, having a Cl₂/CO volume ratio equal to about 1. The total apparent reaction order with respect to Cl₂ + CO in Cl₂-CO-N₂ gas mixture is about 1.5 for a Cl₂/CO ratio equal to 1. Laboratoire Environnement et Minéralurgie, associated with the Centre National de la Recherche Scientifique, Mineral Processing and Environmental Engineering team.     

Role of clinical trials in memory clinics

The main points of a workshop on the place of clinical trials in the memory clinics in France are reproduced schematically. The efficiency of these centres has been tested at the time of the numerous clinical trials performed in France on Alzheimer's disease. In parallel, several difficulties have been pointed out: inhomogeneity of the technical approaches, official role of psychologists in the hospital teams, integration of clinical research to individual care. A particular effort should be oriented towards specific research on the different types of dementia, on early stages, on information for both media and authorities as well as on specific technical and methodological problems.     

Drug abuse patterns, personality characteristics, and relationships with sex, race, and sensation seeking.

Examined interrelationships among sex, race, drug use patterns, and personality variables in 84 chronic users of illicit drugs (mean age 24.3 yrs). Ss were administered the MMPI, the Sensation Seeking Scale, and the Shipley-Institute of Living Scale for Measuring Intellectual Impairment and were interviewed using the Background Information Questionnaire. Comparisons were made between sex and ethnic subgroups on personality and drug use variables using analysis of covariance and chi-square procedures for Ss classified into high-, medium-, and low-sensation-seeking groups. Blacks were characterized by lower levels of sensation seeking, less psychopathology, use of fewer drug categories, and later drug use than Whites. Use and personality patterns among women differed little from those of men. Levels of sensation seeking were related to specific personality constellations, number of drug categories used, and motive for first alcohol use. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amino Acid‐Selective Segmental Isotope Labeling of Multidomain Proteins for Structural Biology

Current solution NMR techniques enable structural investigations of proteins in molecular particles with sizes up to several hundred kDa. However, the large molecular weight of proteins in such systems results in increased numbers of NMR signals, and the resulting spectral overlap typically imposes limitations. For multidomain proteins, segmental isotope labeling of individual domains facilitates the spectral interpretation by reducing the number of signals, but for large domains with small signal dispersion, signal overlap can persist. To overcome limitations arising from spectral overlap, we present a strategy that combines cell‐free expression and ligation of the expressed proteins to produce multidomain proteins with selective amino acid‐type labeling in individual domains. The bottleneck of intrinsically low cell‐free expression yields of precursor molecules was overcome by introducing new fusion constructs that allowed milligram production of ligation‐competent domains labeled in one or multiple amino acid types. Ligation‐competent unlabeled partner domains were produced in vivo, and subsequent domain ligation was achieved by using an on‐column strategy. This approach is illustrated with two multidomain RNA‐binding proteins, that is, the two C‐terminal RNA‐recognition motifs of the human polypyrimidine tract‐binding protein, and two highly homologous helix–turn–helix domains of the human glutamyl‐prolyl‐tRNA synthetase.     

Deuterium ion-surface interactions of liquid-lithium thin films on micro-porous molybdenum substrates

Lithium has been utilized to enhance the plasma performance for a variety of fusion devices such as TFTR, CDX-U and NSTX. Lithium in both the solid and liquid states has been studied extensively for its role in hydrogen retention and reduction in sputtering yield. A liquid lithium diverter (LLD) was recently installed in the National Spherical Torus Experiment (NSTX) fusion reactor to investigate lithium applications for plasma-facing surfaces (PFS). Representative samples of LLD material were exposed to lithium depositing and simulated plasma conditions offline at Purdue University to study changes in surface chemical functionalities of Mo, O, Li and D. X-ray photoelectron spectroscopy (XPS) conducted on samples revealed two distinct peak functionalities of lithiated porous molybdenum exposed to deuterium irradiation. The two-peak chemical functionality noticed in porous molybdenum deviates from similar studies conducted on lithiated graphite; such deviation in data is correlated to the complex surface morphology of the porous surface and the correct “wetting” of lithium on the sample surface. The proper lithium “wetting” on the sample surface is essential for maximum deuterium retention and corresponding LLD pumping of deuterium.