Hydroxylated Analogues of 5-Aminovaleric Acid as 4-Aminobutyric AcidB Receptor Antagonists: Stereostructure-Activity Relationships

The (R) and (S) forms of 5-amino-2-hydroxyvaleric acid (2-OH-DAVA) and 5-amino-4-hydroxyvaleric acid (4-OH-DAVA) were designed as structural hybrids of the 4-aminobutyric acidB (GABAB) agonist (R)-(-)-4-amino-3-hydroxybutyric acid [(R)-(-)-3-OH-GABA] and the GABAB antagonist 5-aminovaleric acid (DAVA). (S)-(-)-2-OH-DAVA and (R)-(-)-4-OH-DAVA showed a moderately potent affinity for GABAB receptor sites in rat brain and showed GABAB antagonist effects in a guinea pig ileum preparation. The respective enantiomers, (R)-(+)-2-OH-DAVA and (S)-(+)-4-OH-DAVA, were markedly weaker in both test systems. All four compounds were weak inhibitors of GABAA receptor binding in rat brain, and none of them significantly affected synaptosomal GABA uptake. Based on molecular modeling studies it has been demonstrated that low-energy conformations of (R)-(-)-3-OH-GABA, (S)-(-)-2-OH-DAVA, and (R)-(-)-4-OH-DAVA can be superimposed. These conformations may reflect the shapes adopted by these conformationally flexible compounds during their interaction with GABAB receptors. The present studies emphasize the similar, but distinct, constraints imposed on agonists and antagonists for GABAB receptors.     

ASF/SF2 and SC35 regulate the glutamate receptor subunit 2 alternative flip/flop splicing

The properties of the glutamate receptor subunits 1-4 (GluR1-4) are influenced by the alternative splicing of two homologous and mutually exclusive exons flip and flop. The flip form is most abundant during early development, while the flop form is dominant in adults. From transfections with a GluR2 mini-gene we show that flip is the preferred splice form in all tested cell lines, but coexpression of the SR-proteins ASF/SF2 and SC35 increases the flop to flip splice ratio. The increased flop incorporation depends on ASF/SF2- and SC35-dependent enhancer elements located in the flop exon, which stimulate the splicing between the flop exon and the preceding exon 13.     

SNP mining porcine ESTs with MAVIANT, a novel tool for SNP evaluation and annotation

MOTIVATION: Single nucleotide polymorphisms (SNPs) analysis is an important means to study genetic variation. A fast and cost-efficient approach to identify large numbers of novel candidates is the SNP mining of large scale sequencing projects. The increasing availability of sequence trace data in public repositories makes it feasible to evaluate SNP predictions on the DNA chromatogram level. MAVIANT, a platform-independent Multipurpose Alignment VIewing and Annotation Tool, provides DNA chromatogram and alignment views and facilitates evaluation of predictions. In addition, it supports direct manual annotation, which is immediately accessible and can be easily shared with external collaborators. RESULTS: Large-scale SNP mining of polymorphisms bases on porcine EST sequences yielded more than 7900 candidate SNPs in coding regions (cSNPs), which were annotated relative to the human genome. Non-synonymous SNPs were analyzed for their potential effect on the protein structure/function using the PolyPhen and SIFT prediction programs. Predicted SNPs and annotations are stored in a web-based database. Using MAVIANT SNPs can visually be verified based on the DNA sequencing traces. A subset of candidate SNPs was selected for experimental validation by resequencing and genotyping. This study provides a web-based DNA chromatogram and contig browser that facilitates the evaluation and selection of candidate SNPs, which can be applied as genetic markers for genome wide genetic studies. AVAILABILITY: The stand-alone version of MAVIANT program for local use is freely available under GPL license terms at http://snp.agrsci.dk/maviant. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.     

Reduction of extraction times in liquid-phase microextraction

Recently, we introduced a simple and inexpensive disposable device for liquid-phase microextraction (LPME) based on porous polypropylene hollow fibres. In the present paper, extraction times were significantly reduced by an increase in the surface of the hollow fibres. The model compounds methamphetamine and citalopram, were extracted from 2.5 ml of urine, plasma, and whole blood after dilution with water and alkalisation with 125 μl of 2 M NaOH though a porous polypropylene hollow fibre impregnated with hexyl ether and into an aqueous acceptor phase consisting of 0.1 M HCl. Two commercially available hollow fibres, which differed in surface area, wall thickness and internal diameter, were compared. An increase in the contact area of the hollow fibre with the sample solution by a factor of approximately two resulted in reduction in equilibrium times by approximately the same factor. Thus, the model compounds were extracted to equilibrium within 15 min from both urine and plasma, and within 30 min from whole blood. For the first time LPME was utilised to extract drugs from whole blood, and the extracts were comparable with plasma both with regard to sample clean-up and extraction recoveries. Extraction recoveries for methamphetamine and citalopram varied from 60 to 100% using the two fibres and the different matrices.     

20-year trajectories of positive and negative symptoms after the first psychotic episode in patients with schizophrenia spectrum disorder: results from the OPUS study

This study aimed to identify the 20-year trajectories of positive and negative symptoms after the first psychotic episode in a sample of patients with an ICD-10 diagnosis of schizophrenia spectrum disorder, and to investigate the baseline characteristics and long-term outcomes associated with these trajectories. A total of 373 participants in the OPUS trial were included in the study. Symptoms were assessed at baseline and after 1, 2, 5, 10 and 20 years using the Scales for the Assessment of Positive and Negative Symptoms. We used latent class growth mixture modelling to identify trajectories, and multinominal regression analyses to investigate predictors of membership to identified trajectories. Five trajectories of positive symptoms were identified: early continuous remission (50.9% of the sample), stable improvement (18.0%), intermittent symptoms (10.2%), relapse with moderate symptoms (11.9%), and continuous severe symptoms (9.1%). Substance use disorder (odds ratio, OR: 2.83, 95% CI: 1.09-7.38, p=0.033), longer duration of untreated psychosis (OR: 1.02, 95% CI: 1.00-1.03, p=0.007) and higher level of negative symptoms (OR: 1.60, 95% CI: 1.07-2.39, p=0.021) were predictors of the relapse with moderate symptoms trajectory, while only longer duration of untreated psychosis (OR: 1.01, 95% CI: 1.00-1.02, p=0.030) predicted membership to the continuous severe symptoms trajectory. Two trajectories of negative symptoms were identified: symptom remission (51.0%) and continuous symptoms (49.0%). Predictors of the continuous symptoms trajectory were male sex (OR: 3.03, 95% CI: 1.48-6.02, p=0.002) and longer duration of untreated psychosis (OR: 1.01, 95% CI: 1.00-1.02, p=0.034). Trajectories displaying continuous positive and negative symptoms were linked to lower neurocognition, as measured by the Brief Assessment of Cognition in Schizophrenia (BACS) (z-score: –0.78, CI: –1.39 to –0.17, for continuous positive symptoms; z-score: –0.33, CI: –0.53 to –0.13, for continuous negative symptoms). The same trajectories were also linked to higher use of antipsychotic medication at 20-year follow-up (continuous positive symptoms: 78%; continuous negative symptoms: 67%). These findings suggest that the majority of patients with first-episode schizophrenia spectrum disorder have a trajectory with early stable remission of positive symptoms. Long duration of untreated psychosis and comorbid substance abuse are modifiable predictors of poor trajectories for positive symptoms in these patients. In about half of patients, negative symptoms do not improve over time. These symptoms, in addition to being associated with poor social and neurocognitive functioning, may prevent patients from seeking help.     

Prolonged hypoxic culture and trypsinization increase the pro-angiogenic potential of human adipose tissue-derived stem cells

Background aimsTransplantation of mesenchymal stromal cells (MSC), including adipose tissue-derived stem cells (ASC), is a promising option in the treatment of vascular disease. Short-term hypoxic culture of MSC augments secretion of anti-apoptotic and angiogenic cytokines. We hypothesized that prolonged hypoxic (1% and 5% oxygen) culture and trypsinization would augment ASC expression of anti-apoptotic and angiogenic cytokines and increase the angiogenic potential of ASC-conditioned media.MethodsThe effects of prolonged hypoxic culture on growth and pro-angiogenic properties were investigated using human ASC cultured at 1%, 5% and 21% oxygen. The effect of trypsinization on the expression of pro-angiogenic genes was also determined.ResultsTrypsinization induced up-regulation of the vascular endothelial growth factor (VEGF) and insulin-like growth factor-1 (IGF-1) genes independent of oxygen concentration. The expression of VEGF and IGF-1 was up-regulated in ASC cultured at 1% oxygen for 13 days compared with 4 days. The VEGF concentration in ASC-conditioned media was higher after prolonged hypoxic culture compared with short-term culture, while the IGF-1 and chemokine (CXC motif) ligand 12 (CXCL12) concentrations were unchanged. The VEGF receptor blocker SU5416 abolished angiogenesis in a cultured rat aortic ring model. Media from cells exposed to hypoxia increased angiogenesis, an effect that was dependent on factors other than just the VEGF concentration in the added media.ConclusionsOptimization of the angiogenic potential of stem cell-based therapy in the treatment of vascular disease is important. We have demonstrated that prolonged hypoxic culture and trypsinization augment the therapeutic angiogenic potential of ASC.     

The value of three cereal aphid species as food for a generalist predator

The value of the cereal aphid species Metopolophium dirhodum (Wlk.), Sitobion avenae (F.) and Rhopalosiphum padi (L.) as prey for the linyphiid spider Erigone atra (Bl.) was assessed. Fecundity of females was determined for spiders fed on eight experimental diets: three single‐species aphid diets, a mixed diet of all three aphid species, three mixed diets with each aphid species in combination with fruit flies Drosophila melanogaster (Meig.), and pure D. melanogaster as a high quality comparison diet. The development and survival of first‐instar juveniles fed on three diets of single aphid species, and on a diet of Collembola were compared with those subjected to starvation. Prey value for adult females was assessed by egg production, hatching success and offspring size. In pure diets all three aphid species were of low value to the spiders, causing a rapid decline in egg production and supporting no growth of significance of first‐instar juveniles. No difference in value of aphid species of single‐species aphid diets was found in the fecundity experiment, while a ranking of aphid species of M. dirhodum > R. padi > S. avenae was revealed in the survivorship experiment. A mixed‐aphid diet was not found to be advantageous compared with single‐species aphid diets, and no advantage of including aphids in mixed diets with fruit flies was found. Metopolophium dirhodum and R. padi were neutral in mixed diets, while a diet of S. avenae and fruit flies caused reduced egg production compared with the pure diet of fruit flies, revealing a toxic effect of S. avenae on the spider. The value‐ranking of aphid species in mixed diets was similar to that of single‐species diets. A similar ranking of aphid species was found for different fitness parameters (fecundity of adult females and development of juveniles). A ranking of aphids by offspring size of mothers on aphid‐only diets was S. avenae > M. dirhodum > R. padi. All aphid‐fruit fly diets resulted in larger offspring than a diet of only D. melanogaster, with the overall largest offspring being produced on the diet of M. dirhodum and fruit flies.