Single-step procedure for gas chromatography-mass spectrometry screening and quantitative determination of amphetamine-type stimulants and related drugs in blood, serum, oral fluid and urine samples

We describe a rapid GC/MS assay for amphetamine-type stimulant drugs (ATSs) and structurally related common medicaments in blood, serum, oral fluid and urine samples. The drugs were extracted from their matrices and derivatized with heptafluorobutyric anhydride (HFBA) in a single step, using the following procedure: 100 microl (oral fluid) or 200 microl (blood, serum, urine) of the sample were mixed with 50 microl of alkaline buffer and 500 microl of extraction-derivatization reagent (toluene + HFBA + internal standard), centrifuged, and injected into a GC/MS apparatus. As revealed by the validation data this procedure, with its limit of quantitation being set at 20 ng/ml for oral fluid, 25 ng/ml for blood or 200 ng/ml for urine, is suitable for screening, identification and quantitative determination of the ATSs and related drugs in all the matrices examined. Thus, time-consuming and expensive multiple analyses are not needed, unless specifically required.     

Glutamate uptake in blood platelets from epileptic patients

Glutamate, the major excitatory amino acid neurotransmitter, is involved in epileptogenesis and initiation and spread of seizures. We studied glutamate uptake into blood platelets from patients with distinct epileptic syndromes: included were 20 patients with temporal lobe epilepsy and hippocampal sclerosis (TLE+HS), 20 with juvenile myoclonus epilepsy (JME) and 20 healthy volunteers matched for age and sex. The affinity of glutamate for the transporters was highest in patients with TLE+HS, but the maximal velocity of transport was highest in controls. There were no differences in the plasma levels of glutamate. Carbamazepine (CBZ), valproate (VPA) and lamotrigine (LTG) did not affect the uptake in vitro. The alterations observed in the uptake of glutamate in TLE+HS patients may reflect an up-regulated uptake of glutamate in the brain.     

Involvement of Metabotropic Glutamate Receptors in Ischemia-Induced Taurine Release in the Developing and Adult Hippocampus

Metabotropic glutamate receptors have recently been envisaged as involved in both potentiation and prevention of ischemic and excitotoxic neuronal damage. The release of the inhibitory amino acid taurine is markedly enhanced in ischemia in both the immature and mature mouse hippocampus. The modulation of [³H]taurine release by metabotropic receptor agonists and antagonists was studied in hippocampal slices from developing (7-day-old) and adult (3-month-old) mice using a superfusion system. Agonists of group I, II and III metabotropic glutamate receptors generally reduced the ischemia-induced release in adult animals. In the immature hippocampus the group I agonists (S)-3,5-dihydroxyphenylglycine and (1±)-1-aminocyclopentane-trans-1,3-dicarboxylate, which mainly enhance neuronal excitation, potentiated initial taurine release in ischemia. Ionotropic glutamate receptor agonists also enhance the ischemia-induced taurine release in developing mice. This glutamate-activated taurine release may thus constitute an important protective mechanism against excitotoxicity in the immature hippocampus.     

Role of adenosine in regulating the heterogeneity of skeletal muscle blood flow during exercise in humans.

Evidence from both animal and human studies suggests that adenosine plays a role in the regulation of exercise hyperemia in skeletal muscle. We tested whether adenosine also plays a role in the regulation of blood flow (BF) distribution and heterogeneity among and within quadriceps femoris (QF) muscles during exercise, measured using positron emission tomography. In six healthy young women, BF was measured at rest and then during three incremental low and moderate intermittent isometric one-legged knee-extension exercise intensities without and with theophylline-induced nonselective adenosine receptor blockade. BF heterogeneity within muscles was calculated from 16-mm(3) voxels in BF images and heterogeneity among the muscles from the mean values of the four QF compartments. Mean BF in the whole QF and its four parts increased, and heterogeneity decreased with workload both without and with theophylline (P < 0.001). Adenosine receptor blockade did not have any effect on mean bulk BF or BF heterogeneity among the QF muscles, yet blockade increased within-muscle BF heterogeneity in all four QF muscles (P = 0.03). Taken together, these results show that BF becomes less heterogeneous with increasing exercise intensity in the QF muscle group. Adenosine seems to play a role in muscle BF heterogeneity even in the absence of changes in bulk BF at low and moderate one-leg intermittent isometric exercise intensities.     

The endoplasmic reticulum Ca2+-pump SERCA2b interacts with G protein-coupled receptors and enhances their expression at the cell surface

Calcium (Ca(2+)) plays a pivotal role in both cellular signaling and protein synthesis. However, it is not well understood how calcium metabolism and synthesis of secreted and membrane-bound proteins are related. Here we demonstrate that the sarco(endo)plasmic reticulum Ca(2+) ATPase 2b (SERCA2b), which maintains high Ca(2+) concentration in the lumen of the endoplasmic reticulum, interacts specifically with the human delta opioid receptor during early steps of receptor biogenesis in human embryonic kidney 293 cells. The interaction involves newly synthesized incompletely folded receptor precursors, because the association between the delta opioid receptor and SERCA2b (i) was short-lived and took place soon after receptor translation, (ii) was not affected by misfolding of the receptor, and (iii) decreased if receptor folding was enhanced by opioid receptor pharmacological chaperone. The physical association with SERCA2b was found to be a universal feature among G protein-coupled receptors within family A and was shown to occur also between the endogenously expressed luteinizing hormone receptor and SERCA2b in rat ovaries. Importantly, active SERCA2b rather than undisturbed Ca(2+) homeostasis was found to be essential for delta opioid receptor biogenesis, as inhibition of its Ca(2+) pumping activity by thapsigargin reduced the interaction and impaired the efficiency of receptor maturation, two phenomena that were not affected by a Ca(2+) ionophore A23187. Nevertheless, inhibition of SERCA2b did not compromise the functionality of receptors that were able to mature. Thus, we propose that the association with SERCA2b is required for efficient folding and/or membrane integration of G protein-coupled receptors.     

Macroalgae in biofuel production

The conversion processes of macroalgae for biofuels can be divided into thermochemical (dry) and microbiological (wet) processes. The chemical composition of macroalgae together with the pre‐treatment method, conversion conditions, and the characteristics of the microbes involved (wet processes) determine the yield and the properties of the biofuel produced. Macroalgae are often rich in carbohydrates, and therefore well suited for biogas, biobutanol and bioethanol productions. The content of triacylglycerols (TAGs) is the best indicator for the suitability of the alga for biodiesel production. TAGs have a high conversion rate to biodiesel, high percentage of fatty acids, and they lack phosphorus, sulfur and nitrogen. Macroalgae can have high metal concentrations, which can have an impact on conversion processes: metals may inhibit or catalyse the processes. High sulfur (especially in green algae) and nitrogen contents are also characteristic to macroalgae, and may be problematic in the production of biogas (NH₃‐toxicity) and the use of the oil and biodiesel (high concentrations of H₂S and NO_x‐compounds). Macroalgae have proven to be suitable material for conversion processes, but further optimization of the processes is needed. At present, macroalgae are not economically, or in many cases not even environmentally, sustainable material when the whole production chain is considered. In this review we summarize information on the chemical composition of macroalgae in a prospect of biofuel production, and the current situation in the field of macroalgal‐based biofuel production.     

Allelopathic Effects of Toxic Haptophyte <Emphasis Type="Italic">Prymnesium parvum</Emphasis> Lead to Release of Dissolved Organic Carbon and Increase in Bacterial Biomass

The haptophyte Prymnesium parvum has lytic properties, and it affects coexisting phytoplankton species through allelopathy. We studied the effect of P. parvum allelochemicals on the lysis of the nontoxic and nonaxenic cryptomonad Rhodomonas salina and the consequent release of dissolved organic carbon (DOC). Changes in production, cell density, and biomass of associated bacteria were measured over 12 h. Six different combinations of P. parvum and R. salina cultures, their cell- and bacteria-free filtrates, and growth media as controls were used in the experiments. When P. parvum and R. salina cells were mixed, a significant increase in DOC concentration was measured within 30 min. Bacterial biomass increased significantly during the next 6 to 12 h when R. salina was mixed either with the P. parvum culture or the cell-free P. parvum filtrates (allelochemicals only). In contrast, bacterial biomass did not change in the treatments without the allelopathic action (without R. salina cells). Blooms of P. parvum alter the functioning of the planktonic food web by increasing carbon transfer through the microbial loop. In addition, P. parvum may indirectly benefit from the release of DOC as a result of its ability to ingest bacteria, by which it can acquire nutrients during limiting conditions.     

Association between Dopamine Receptor D2 (DRD2) Variations rs6277 and rs1800497 and Cognitive Performance According to Risk Type for Psychosis: A Nested Case Control Study in a Finnish Population Sample

Background

There is limited research regarding the association between genes and cognitive intermediate phenotypes in those at risk for psychotic disorders.

Methods

We measured the association between established psychosis risk variants in dopamine D2 receptor (DRD2) and cognitive performance in individuals at age 23 years and explored if associations between cognition and these variants differed according to the presence of familial or clinical risk for psychosis. The subjects of the Oulu Brain and Mind Study were drawn from the general population-based Northern Finland 1986 Birth Cohort (NFBC 1986). Using linear regression, we compared the associations between cognitive performance and two candidate DRD2 polymorphisms (rs6277 and rs1800497) between subjects having familial (n=61) and clinical (n=45) risk for psychosis and a random sample of participating NFBC 1986 controls (n=74). Cognitive performance was evaluated using a comprehensive battery of tests at follow-up.

Results

Principal components factor analysis supported a three-factor model for cognitive measures. The minor allele of rs6277 was associated with poorer performance on a verbal factor (p=0.003) but this did not significantly interact with familial or clinical risk for psychosis. The minor allele of rs1800497 was associated with poorer performance on a psychomotor factor (p=0.038), though only in those at familial risk for psychotic disorders (interaction p=0.049).

Conclusion

The effect of two DRD2 SNPs on cognitive performance may differ according to risk type for psychosis, suggesting that cognitive intermediate phenotypes differ according to the type (familial or clinical) risk for psychosis.     

The acyl lipid composition of wheat leaves and moss protonemata using a new, non-carcinogenic extraction solvent system

As chloroform has proved to be carcinogenic we were looking for an alternative solvent system for chloroform:methanol widely used in plant lipid investigations. The lipids from leaves of wheat ( Triticum aestivum L. cv. Vakka) and from protonemata of the moss Ceratodon purpureus (Hedw.) Brid. were extracted with two petroleum ether:methanol solvent systems. The polar lipids were separated by two-dimensional thin-layer chromatography and the amounts of each lipid class were compared with those obtained from chloroform:methanol (2:1, v/v) extractions. The significantly higher amounts of phosphatidylinositol observed in petroleum ether:methanol (1:1, v/v) extraction suggest that the small amounts reported earlier in plants may be an artefact relating to the solvent system used. As petroleum ether:methanol (1:1, v/v) proved to be at least as good a solvent system as chloroform:methanol (2:1, v/v) we propose it as an alternative extractant for plant polar lipids.     

Interference of S-Nitrosoglutathione with the Binding of Ligands to Ionotropic Glutamate Receptors in Pig Cerebral Cortical Synaptic Membranes

The interactions of S-nitrosoglutathione (GSNO) with the ionotropic glutamate receptors were studied on synaptic membranes isolated from the pig cerebral cortex. GSNO displaced the binding of [³H]glutamate, 3-[(R)-2-carboxypiperazin-4-yl][³H]propyl-1-phosphonate ([³H]CPP), a competitive N-methyl-D-aspartate (NMDA) antagonist, and [³H]kainate, with IC₅₀ values in the low micromolar range. It failed to displace (S)-5-fluoro-[³H]willardiine, a selective agonist of 2-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors. Reduced and oxidized glutathione were almost as effective as GSNO in glutamate and CPP binding. Of the three, GSNO was the most potent in kainate binding. They all stimulated [³H]dizocilpine binding in a concentration-dependent manner. This effect was additive to that of glycine and not mimicked by NO donors such as S-nitroso-N-acetylpenicillamine, 5-amino-3-morpholinyl-1,2,3-oxadiazolium chloride (SIN-1) and nitroglycerin. We assume that GSNO may act as an endogenous ligand at the NMDA and non-NMDA classes of glutamate receptors. In this manner it may facilitate NO transfer and target its delivery to specific sites in these receptors.