<Emphasis Type="Italic">N</Emphasis>-arachidonoyl glycine,an abundant endogenous lipid,potently drives directed cellular migration through GPR18, the putative abnormal cannabidiol receptor

Background  

Microglia provide continuous immune surveillance of the CNS and upon activation rapidly change phenotype to express receptors that respond to chemoattractants during CNS damage or infection. These activated microglia undergo directed migration towards affected tissue. Importantly, the molecular species of chemoattractant encountered determines if microglia respond with pro- or anti-inflammatory behaviour, yet the signaling molecules that trigger migration remain poorly understood. The endogenous cannabinoid system regulates microglial migration via CB₂ receptors and an as yet unidentified GPCR termed the 'abnormal cannabidiol' (Abn-CBD) receptor. Abn-CBD is a synthetic isomer of the phytocannabinoid cannabidiol (CBD) and is inactive at CB₁ or CB₂ receptors, but functions as a selective agonist at this G_i/o-coupled GPCR. N-arachidonoyl glycine (NAGly) is an endogenous metabolite of the endocannabinoid anandamide and acts as an efficacious agonist at GPR18. Here, we investigate the relationship between NAGly, Abn-CBD, the unidentified 'Abn-CBD' receptor, GPR18, and BV-2 microglial migration.     

STUDIES OF ADHESION OF METAL PARTICLES TO SILICA PARTICLES BASED ON ZETA POTENTIAL MEASUREMENTS

The zeta-potentials of silica, copper, platinum and gold particles have been measured as a function of pH. The isoelectric points were found to be at pH 3.0, 5.8, 3.0 and 3.5, respectively. In the pH range 3.0 to 5.8 copper and silica particles are oppositely charged and accordingly the coating of silica with copper particles could be demonstrated. In the case of gold and platinum the sign of the charge is such that direct adhesion to silica particles cannot be expected and this was also demonstrated in the case of platinum.     

Luminescent silole nanoparticles as chemoselective sensors for Cr(VI)

Colloidal suspensions of 3-aminopropylmethyl(tetraphenyl)silole nanoparticles can be used as selective chemosensors for carcinogenic chromium(VI) analyte. Methylhydrosilole is functionalized by hydrosilation of allylamine, and the colloid is prepared by the rapid addition of water to a THF solution of the silole. The method of detection is through electron-transfer quenching of the fluorescence of the silole colloid (lambda(em) = 485 nm at 360 nm excitation) by the analytes, with hundred parts per billion detection limits. Stern-Volmer plots are linear up to 10 ppm in the case of chromium, but exhibit saturation behavior near 5-10 ppm for arsenic. Dynamic light scattering experiments and AFM measurements show the particle sizes to be around 100 nm in diameter and dependent on solvent composition, with a particle size dispersity of +/-25%. The fluorescence lifetimes of the silole in solution and colloid are approximately 31 ps and approximately 4.3 ns, respectively, while the silole has a lifetime of 6 ns in the bulk solid. A minimum volume fraction of 80% water is necessary to precipitate the colloid from THF, and the luminescence continues to rise with higher water fractions. Colloids in a pH 7 phosphate-buffered suspension show both higher sensitivity and greater selectivity (100-fold) for CrO4(2-) detection than for other oxoanion interferents, NO3-, NO2-, SO4(2-), and ClO4-.     

Randomizing the Unfolded State of Peptides (and Proteins) by Nearest Neighbor Interactions between Unlike Residues

To explore the influence of nearest neighbors on conformational biases in unfolded peptides, we combined vibrational and 2D NMR spectroscopy to obtain the conformational distributions of selected “GxyG” host–guest peptides in aqueous solution: GDyG, GSyG, GxLG, GxVG, where x/y=A, K, L, V. Large changes of conformational propensities were observed due to nearest‐neighbor interactions, at variance with the isolated pair hypothesis. We found that protonated aspartic acid and serine lose their above‐the‐average preference for turn‐like structures in favor of polyproline II (pPII) populations in the presence of neighbors with bulky side chains. Such residues also decrease the above‐the‐average pPII preference of alanine. These observations suggest that the underlying mechanism involves a disruption of the hydration shell. Thermodynamic analysis of ³J(H^N,H^α) (T) data for each x,y residue reveals that modest changes in the conformational ensemble masks larger changes of enthalpy and entropy governing the pPII?β equilibrium indicating a significant residue dependent temperature dependence of the peptides’ conformational ensembles. These results suggest that nearest‐neighbor interactions between unlike residues act as conformational randomizers close to the enthalpy–entropy compensation temperature, eliminating intrinsic biases in favor of largely balanced pPII/β dominated ensembles at physiological temperatures.     

Roughness measurement of metallic surfaces based on the laser speckle contrast method

A method of measuring surface roughness of flat lapped, ground and polished metallic surfaces, by the far-field speckle contrast method is presented in this paper. The laser speckle contrast technique depends on the existence of an approximately linear relationship between the speckle contrast and the roughness of the illuminated surface. Initially it was shown that the linear relationship existed up to 0.1 μm Ra (centre-line average) roughness using Helium–Neon light, after which a saturation effect was observed. The effect of varying the incident angle of illumination was investigated with a view to extending the measurement range. The use of high incident angles of illumination has been found to increase the surface roughness range up to 0.4 μm measurement Ra.     

Electro-optical switching of liquid crystal diffraction gratings by using surface relief effect in the photopolymer

Surface relief patterns are one of the promising possibilities for the fabrication of liquid crystal (LC) electro-optical devices. Optically recorded surface relief gratings in an acrylamide based photopolymer were filled with the liquid crystal to fabricate liquid crystal diffraction gratings. E49 liquid crystals were used in this work. The switching behaviour of the diffraction grating was investigated by measuring the intensity in the first order when an electric field was applied.     

A multiple laser beam probe system for turbulence diagnostics

Deatils are given of a multiple laser beam probe for sizing and velocity measurements in turbulent media. Sample results are presented in the case of thermal turbulent convection in a model buble chamber.