Chromatographic determination of the absolute configuration of an acyclic secondary alcohol using difluorodinitrobenzene

A chromatographic determination method was developed for the absolute configuration of an acyclic secondary alcohol using the characteristic functions of 1,5-difluoro-2,4-dinitrobenzene (FFDNB). This method relies on the formation of the fixed favorable conformation of a secondary alcohol-DLA (2,4-dinitrophenyl-5-leucinamide) derivative and its recognition by ODS silica gel. The secondary alcohol reacted first with FFDNB under mild basic conditions, and L-leucinamide or DL-leucinamide was then introduced into the secondary alcohol-FDNB derivative. Because the conformations of the resulting alcohol-DLA derivatives were rigidly fixed by the dinitrobenzene plane, the absolute configuration at the asymmetric carbon of the secondary alcohol tested can be definitely deduced by the elution behavior of both of the diastereomers in the HPLC and/or LC/MS. One of the diastereomers has the cis (Z)-type arrangement of two more hydrophobic substituents of the alcohol and leucinamide moieties, the more hydrophobic side chain and isobutyl groups, to the plane of the dinitrobenzene, whereas another diastereomer has the opposite arrangement (trans (E)-type). Therefore, the cis arrangement interacts more strongly with the ODS silica gel and has a longer retention time than that of the trans-type arrangement. This established method was successfully applied to various chiral acyclic secondary alcohols including chloramphenicol and 4-hydroxyphenyllactic acid. Finally, the limitations of this method were also examined.     

Classical/nonclassical hybrid cannabinoids: southern aliphatic chain-functionalized C-6beta methyl, ethyl, and propyl analogues

The stereoelectronic requirements for interaction of the southern aliphatic hydroxyl of cannabimimetic pharmacophores with the CB1 and CB2 receptors are explored. The stereoselective syntheses of three series of classical/nonclassical hybrid cannabinoids are described. These compounds were designed to investigate the importance of the southern aliphatic hydroxyl (SAH) pharmacophore for cannabimimetic activity. Variation in the chain length of the SAH moiety in these 6beta-(hydroxyalkyl)dihydrobenzopyran analogues, from 6beta-hydroxymethyl to 6beta-(omega-hydroxyethyl) and 6beta-(omega-hydroxypropyl), and the effects of replacing the hydroxyl functionality by hydride and iodide are reported. Our results indicate that the SAH pharmacophore has less pronounced effects than the C-3 aliphatic chain on cannabinoid activity. Furthermore, it appears that this southern molecular component is capable of interacting with two different subsites on the receptor and that the nature of this interaction is determined by the terminal substituent on the C-6beta alkyl group. One of the subsites can accommodate the relatively polar SAH pharmacophore, while the second subsite interacts with more hydrophobic C-6beta substituents and can accommodate large spherical pharmacophores separated by three methylene carbons from the tricyclic cannabinoid template.     

Changes in vasoactive intestinal peptide mRNA levels in the rat suprachiasmatic nucleus following p-chlorophenylalanine (PCPA) treatment under light/dark conditions

Photic stimulus and serotonin (5-hydroxytryptamine; 5-HT) are two factors known to regulate vasoactive intestinal peptide (VIP) synthesis in the suprachiasmatic nucleus (SCN). To explore the role of 5-HT in the photic stimulus-induced change in VIP synthesis, we investigated the changes in level of VIP mRNA under a 12 h light/12 h dark cycle following depletion of 5-HT by intraperitoneal administration of p-chlorophenylalanine (PCPA) methyl ester (200 mg/kg concentration) for 3 successive days. To estimate VIP mRNA expression, we performed in situ hybridization using imaging plates combined with microcomputer-based imaging analysis. In light-phase, total signals of VIP mRNA from the PCPA-treated rats showed a significant decrease compared with those from the saline-treated control rats. However, in dark-phase, there were no significant decreases between the PCPA-treated rats and the saline-control rats. The present results strongly suggest that 5-HT neuronal inputs to the SCN interfere with the effect of photic stimulus on VIP synthesis at the mRNA level.     

Performance of a-WO3/LiClO4-PC electrochromic displays

This paper deals with the improvements in response time and reliability of the aWO₃/LiClO₄-PC (propylene carbonate) electrochromic display. Response time was improved by adopting the highly porous a-WO₃ film, the porous reflector and the high surface area non-polarizable counter-electrode. Results from the reliability tests indicated that the ECD had a sufficient lifetime for practical applications such as in watches, clocks and calculators. The mechanism of performance drift upon cycling the display is investigated using ESCA, AES and atomic absorption methods.     

On-demand droplet spotter for preparing pico- to femtoliter droplets on surfaces

A droplet spotter for on-demand generation of pico- to femtoliter droplets was developed to meet the requirement for high-density spotting of chemicals on a surface. Our droplet spotter involves applying a approximately 1000-V and approximately 10-ms pulse voltage to the tip of a capillary tube (o.d. approximately 18 microns; i.d. approximately 11 microns) supplied with water or a dye solution. The capability of the spotter was demonstrated by preparing a microarray of dye molecules. The microarray was prepared by spotting approximately 30-fL droplets of a dye solution on a surface at the density of one spot per 20 x 20 micron 2.     

Mechanisms of tubulin modification by phosphatidylcholine hydroperoxides

The interaction of lipid peroxides with cellular proteins has been postulated to contribute to cellular aging. A potential target for such effects is tubulin, the building block of microtubules. We examined the concentration-dependent effects of phosphatidylcholine hydroperoxides on the ability of tubulin to polymerize into microtubules. The results demonstrated that even very low concentrations of peroxides were sufficient to interfere with the tubulin and, therefore, the microtubule function. Decreased tubulin activity (as measured by tubulin GTPase activity) showed correlation with the modification of methionine and cysteine in tubulin and a change in the tubulin conformational state as indicated by fluorescence and ultraviolet spectroscopic measurements. As no effect on electric conductivity was observed, indicating that modulation of ionic binding was not involved, the interaction mechanism may be a hydrophobic one.     

(Close) distance makes the heart grow fonder: Improving implicit racial attitudes and interracial interactions through approach behaviors.

In 4 studies, the authors examined the effect of approaching Blacks on implicit racial attitudes and immediacy behaviors. In Studies 1-3, participants were trained to pull a joystick toward themselves or to push it away from themselves when presented with photographs of Blacks, Whites, or Asians before completing an Implicit Association Test to measure racial bias. In Study 4, the effect of this training procedure on nonverbal behavior in an interracial contact situation was investigated. Results from the studies demonstrated that approaching Blacks decreased participants' implicit racial prejudice and increased immediacy when interacting with a Black confederate. The implications of these findings for current theories on approach, avoidance, and intergroup relations are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gold nanoparticle distribution monitor for drug delivery system based on optically assisted ultrasonic velocity-change imaging

Optical absorption images of the tissue mimic phantom including gold nanoparticles were obtained by detecting the ultrasonic velocity-change caused by light irradiation. A series of experimental results showed the possibility as a nanoparticle distribution monitor for the drug delivery system.