Determination of Δ-tetrahydrocannabinol from human saliva by tandem immunoaffinity chromatography-high-performance liquid chromatography

Smoking or ingestion of cannabis causes cognitive, perceptual and behavioural changes, which are responsible for impaired performance in driving motor vehicles. In this paper a novel liquid chromatographic assay for the selective quantification of Δ⁹-tetrahydrocannabinol, the major indicator of a present cannabis intoxication in saliva, is described. The method involves a column-switching procedure and requires an extremely simple pre-treatment of the sample. Deproteinized saliva was directly injected into the chromatographic system. The clean-up and enrichment procedure was performed in an immunoaffinity column, followed by the transfer of the antigens to an octylsilica analytical column. The immunoaffinity sorbent was obtained by covalent immobilization of specific antibodies on epoxy-activated silica. The mobile phase consisted of methanol-aqueous 0.15 mol/1 NaCl solution (elution programmed) and the analyte was detected by measuring the UV absorption at 220 nm. Using an injection volume of 4.5 ml (dilution 3:2, v/v) the limit of quantification was 20 ng/ml, at a signal-to-noise ratio of 5. Recoveries were estimated to be in the range of 70%. Both intra- and inter-day coefficients of variation were below 5%     

Senita cactus: a plant with interrupted sterol biosynthetic pathways

Locereol (4α-methylcholesta-8,14-dien-3β-ol) and 5α-cholesta-8,14-dien-3β-ol, not previously isolated from plants, 24-methylenelophenol, lathosterol, 5α-campest -7-en-3β-ol and spinasterol are present in senita cactusin addition to the lophenol and schottenol described previously.     

Investigations on the effects of cobalt-alkyne complexes on leukemia and lymphoma cells: cytotoxicity and cellular uptake

Cobalt-alkyne complexes represent a new class of antiproliferative drugs with high activity on cell lines derived from human solid tumors. These promising results encouraged us to evaluate also their effects against leukemia and lymphoma cells. For this purpose, we selected three cobalt complexes with (2-propyn-1-yl)acetylsalicylate (Co-ASS), 2-propyn-1-ol (Co-Prop) and diphenylacetylene (Co-Diph) ligands and investigated their growth inhibiting properties on the LAMA-84, K-562, SD-1 leukemia and U-937 lymphoma cell lines. The cobalt complexes showed high effects on LAMA-84 cells (IC(50)=7.7-16.8 microM) after 48 and 72 h of incubation, but were inactive (K-562, U-937) or low active (SD-1) on the other cell lines. The proliferation of SD-1 cells was reduced by Co-Prop (IC(50)=18.6 microM) and Co-Diph (IC(50)=7.5 microM) only after a 72 h exposure. The antiproliferative effects did not correlate with the accumulation of the drugs into the tumor cells. The time dependent uptake during 24 h determined by atomic absorption spectroscopy was comparably the same in sensitive LAMA-84 and insensitive K-562 cells.     

FHY1 and FHL act together to mediate nuclear accumulation of the phytochrome A photoreceptor

The phytochrome family of red/far-red photoreceptors is involved in the regulation of a wide range of developmental responses in plants. The Arabidopsis genome contains five phytochromes (phyA-E), among which phyA and phyB play the most important roles. Phytochromes localize to the cytosol in the dark and accumulate in the nucleus under light conditions, inducing specific phytochrome-mediated responses. Light-regulated nuclear accumulation of the phytochrome photoreceptors is therefore considered a key regulatory step of these pathways. In fact, one of the most severe phyA signaling mutants, fhy1 (far red elongated hypocotyl 1), is strongly affected in nuclear accumulation of phyA. The fhy1 fhl (fhy1 like) double mutant, lacking both FHY1 and its only close homolog FHL, is virtually blind to far-red light like phyA null seedlings. Here we show that FHL accounts for residual amounts of phyA in the nucleus in a fhy1 background and that nuclear accumulation of phyA is completely inhibited in an fhy1 FHL RNAi knock-down line. Moreover, we demonstrate that FHL and phyA interact with each other in a light-dependent manner and that they co-localize in light-induced nuclear speckles. We also identify a phyA-binding site at the C-terminus of FHY1 and FHL, and show that the N-terminal 406 amino acids of phyA are sufficient for the interaction with FHY1/FHL.     

Phytochrome A-specific signaling in Arabidopsis thaliana

Among the five phytochromes in Arabidopsis thaliana, phytochrome A (phyA) plays a major role in seedling de-etiolation. Until now more then ten positive and some negative components acting downstream of phyA have been identified. However, their site of action and hierarchical relationships are not completely understood yet.     

Functional connectivity analyses in imaging genetics: considerations on methods and data interpretation

Functional magnetic resonance imaging (fMRI) can be combined with genotype assessment to identify brain systems that mediate genetic vulnerability to mental disorders ("imaging genetics"). A data analysis approach that is widely applied is "functional connectivity". In this approach, the temporal correlation between the fMRI signal from a pre-defined brain region (the so-called "seed point") and other brain voxels is determined. In this technical note, we show how the choice of freely selectable data analysis parameters strongly influences the assessment of the genetic modulation of connectivity features. In our data analysis we exemplarily focus on three methodological parameters: (i) seed voxel selection, (ii) noise reduction algorithms, and (iii) use of additional second level covariates. Our results show that even small variations in the implementation of a functional connectivity analysis can have an impact on the connectivity pattern that is as strong as the potential modulation by genetic allele variants. Some effects of genetic variation can only be found for one specific implementation of the connectivity analysis. A reoccurring difficulty in the field of psychiatric genetics is the non-replication of initially promising findings, partly caused by the small effects of single genes. The replication of imaging genetic results is therefore crucial for the long-term assessment of genetic effects on neural connectivity parameters. For a meaningful comparison of imaging genetics studies however, it is therefore necessary to provide more details on specific methodological parameters (e.g., seed voxel distribution) and to give information how robust effects are across the choice of methodological parameters.