Cocaine reward and locomotion stimulation in mice with reduced dopamine transporter expression

Background  

The dopamine transporter (DAT) plays a critical role in regulating dopamine neurotransmission. Variations in DAT or changes in basal dopaminergic tone have been shown to alter behavior and drug responses. DAT is one of the three known high affinity targets for cocaine, a powerful psychostimulant that produces reward and stimulates locomotor activity in humans and animals. We have shown that cocaine no longer produces reward in knock-in mice with a cocaine insensitive mutant DAT (DAT-CI), suggesting that cocaine inhibition of DAT is critical for its rewarding effect. However, in DAT-CI mice, the mutant DAT has significantly reduced uptake activity resulting in elevated basal dopaminergic tone, which might cause adaptive changes that alter responses to cocaine. Therefore, the objective of this study is to determine how elevated dopaminergic tone affects how mice respond to cocaine.     

Study of the reaction of bis- and tris-pyrylium and -thiopyrylium cations with methoxide ion. Electronic effects of the heterocyclic rings as substituents

The bis- and tris-pyrylium and thiopyrylium cations 1-4 were prepared in gram scale by heterocyclization of the corresponding bis- and tris-1,5-pentanediones 6 and 8. Their reaction with CD3ONa in CD3OD was studied by 1H NMR at -40 degrees C and at +25 degrees C. At low temperature, kinetically controlled mixtures of 2H and/or 4H adducts were detected, whereas at room temperature the mixtures equilibrated to yield, in all of the cases, the more stable 2H adducts exclusively. A spectrophotometric study of the reactions with sodium methoxide in methanol was carried out at 25.0 degrees C with the aim of determining the stepwise equilibrium constants for the addition of MeO- at the alpha position of the heteroaromatic rings. The obtained equilibrium constants allowed the evaluation of the electronic effects of chalcogenopyrylium and 2H-chalcogenopyran subunits as substituents. Despite the different sensitivity to electronic effects, pyrylium and thiopyrylium rings have a similar electron-withdrawing effect with a sigma(+)p approximately 0.8 and a sigma(+)m approximately 0.5. Apart from the expected importance of the inductive effect due to the positive charge, the difference between these two values remarks the importance of the resonance contribution. In contrast both the neutral 2H-pyranyl and thiopyranyl rings have a negligible effect as substituents, independently of the position, para or meta, they occupy.     

The influence of the brewing process on the formation of biogenic amines in beers

Biogenic amines, as dabsyl derivatives, were determined in beer samples, intermediate products, and raw materials (malt and maize) by HPLC. A procedure for the extraction of the amines from malt and maize with diluted hydrochloric acid was optimised by combining a Response Surface Methodology with a Simultaneous Decision Making Approach. The results of the analysis indicate that, in brewing, technology and hygiene are the decisive factors that determine the amine concentrations in the final product.     

A dinuclear copper(II) complex with adeninate bridge ligands and prominent DNA cleavage activity. Structural and spectroscopic characterization and magnetic properties

A new dinuclear copper(II) complex has been synthesized and structurally characterized: [Cu(mu-ade)(tolSO3)(phen)]2.2H2O (Hade = adenine, tolSO3- = toluenesulfonate anion). Its magnetic properties and electronic paramagnetic resonance (EPR) spectra have been studied in detail. The compound has two metal centers bridged by two adeninate NCN groups. The coordination geometry of the copper(II) ions in the dinuclear entity is distorted square pyramidal, with the four equatorial positions occupied by two phenanthroline N atoms and two N atoms from different adenine molecules. The axial position is occupied by one sulfonate O atom. Magnetic susceptibility data show antiferromagnetic behavior with an estimated exchange constant of -2J = 65 cm-1. The EPR spectrum has been obtained at both X- and Q-band frequencies; a study at different temperatures has been carried out at the latter. Above 20 K, the Q-band spectra are characteristic of S = 1 species with a small zero-field splitting parameter (D = 0.0970 cm-1). A detailed study of the DNA-complex interaction has been performed. The title complex efficiently cleaves the pUC18 plasmid in the presence of reducing agents. Both the kinetics and the mechanism of the cleavage reaction are examined and described herein.     

Molecular Imprinting in Sol-Gel Materials: Recent Developments and Applications

Since its inception five decades ago, imprinted sol-gel materials went practically unnoticed, until in the 1970s the conceptual introduction of molecular imprinting in synthetic polymers triggered a new interest in this field. The recent growth in interest in organic–inorganic hybrid materials prepared by sol-gel chemistry and the development of a variety of new strategies for imprinting polymeric matrices have led to a growing activity in what became known as molecularly imprinted sol-gel materials. This paper intends to give an overview of recent progress in molecular imprinting in sol-gel matrices, the potential analytical applications of these tailor-made materials and their limitations, with the aim of drawing attention to useful information and to enhancing interest in this practically unexplored but promising field.     

High-performance flow atomic spectrometry: New nebulization techniques,on-line speciation and on-line sample pretreatment

An interface-free combination of HPLC separation techniques and methods for element determination by atomic spectrometry can be achieved by hydraulic high-pressure nebulization (HHPN). With high-temperature HHPN (300 ( degrees )C) super heated liquids can be nebulized providing aerosol yields of up to 90% in flame AAS. This new nebulization method combines the advantages of HHPN and thermospray techniques (very small aerosol droplets, high aerosol yield, nebulization of saturated salt solutions).     

Enantioselective Organocatalytic Diels–Alder Trapping of Photochemically Generated Hydroxy‐o‐Quinodimethanes

The photoenolization/Diels–Alder strategy offers straightforward access to synthetically valuable benzannulated carbocyclic products. This historical light‐triggered process has never before succumbed to efforts to develop an enantioselective catalytic approach. Herein, we demonstrate how asymmetric organocatalysis provides simple yet effective catalytic tools to intercept photochemically generated hydroxy‐o‐quinodimethanes with high stereoselectivity. We used a chiral organic catalyst, derived from natural cinchona alkaloids, to activate maleimides toward highly stereoselective Diels–Alder reactions. An unconventional mechanism of stereocontrol is operative, wherein the organocatalyst is actively involved in both the photochemical pathway, by leveraging the formation of the reactive photoenol, and the stereoselectivity‐defining event.     

A theoretical study of the hydrogen bond donor capability and co-operative effects in the hydrogen bond complexes of the diaza-aromatic betacarbolines

In this work, we present a quantum mechanical investigation on the hydrogen bond interactions of N(9)-methyl-9H-pyrido[3,4-b]indole, MBC, and N(2)-methyl-9H-pyrido[3,4-b]indole, BCA, with different hydrogen bond donors. Thus, it has been analysed the influence that the hydrogen bond donor strength and the co-operative effect of the increasing number of donor molecules have on the shape of the potential energy surfaces versus the N···H distances, r(N–H). To rationalize the nature of the interactions, the Bader theory has been applied and the characteristics of the bond critical points analysed. The results show that two different hydrogen bond complexes can be formed depending on the donor capabilities or the number of donor molecules included in the calculations. The topological parameters from the Bader theory are used to justify the statement that the analysed interactions can be classified as weak or partially covalent hydrogen bond interactions, respectively. As experimentally observed, weak hydrogen bond donors form weak hydrogen bond complexes, called HBC. Upon the increase of the donor strength the N···H proton is shifted nearest to the nitrogen atom giving rise to the observation of a stronger hydrogen bond complex, the proton transfer complex, PTC. The most outstanding result of these studies is the fact that the formation of the PTC can also be managed just by changing the number of donor molecules, that is, by a co-operative effect of the hydrogen bonds.     

A New Porphyrin for the Preparation of Functionalized Water-Soluble Gold Nanoparticles with Low Intrinsic Toxicity

A potential new photosensitizer based on a dissymmetric porphyrin derivative bearing a thiol group was synthesized. 5-[4-(11-Mercaptoundecyloxy)-phenyl-10,15,20-triphenylporphyrin (PR-SH) was used to functionalize gold nanoparticles in order to obtain a potential drug delivery system. Water-soluble multifunctional gold nanoparticles GNP-PR/PEG were prepared using the Brust–Schiffrin methodology, by immobilization of both a thiolated polyethylene glycol (PEG) and the porphyrin thiol compound (PR-SH). The nanoparticles were fully characterized by transmission electron microscopy and ¹H nuclear magnetic resonance spectroscopy, UV/Vis absorption spectroscopy, and X-ray photoelectron spectroscopy. Furthermore, the ability of GNP-PR/PEGs to induce singlet oxygen production was analyzed to demonstrate the activity of the photosensitizer. Cytotoxicity experiments showed the nanoparticles are nontoxic. Finally, cellular uptake experiments demonstrated that the functionalized gold nanoparticles are internalized. Therefore, this colloid can be considered to be a novel nanosystem that could potentially be suitable as an intracellular drug delivery system of photosensitizers for photodynamic therapy.     

Amorphous Calcium Phosphates: Solvent-Controlled Growth and Stabilization through the Epoxide Route

Calcium phosphates stand among the most promising nanobiomaterials in key biomedical applications, such as bone repairment, signalling or drug/gene delivery. Their intrinsic properties as crystalline structure, composition, particle shape and size define their successful use. Among these compounds, metastable amorphous calcium phosphate (ACP) is currently gaining particular attention due to its inherently high reactivity in solution, which is crucial in bone development mechanisms. However, the preparation of this highly desired (bio)material with control over its shape, size and phase purity remains as a synthetic challenge. In this work, the epoxide route was adapted for the synthesis of pure and stable ACP colloids. By using biocompatible solvents, such as ethylene glycol and/or glycerine, it was possible to avoid the natural tendency of ACP to maturate into more stable and crystalline apatites. Moreover, this procedure offers size control, ranging from small nanoparticles (60 nm) to micrometric spheroids (>500 nm). The eventual fractalization of the internal mesostructured can be tuned, by simply adjusting the composition of the ethylene glycol:glycerine solvent mixture. These findings introduce the use of green solvents as a new tool to control crystallinity and/or particle size in the synthesis of nanomaterials, avoiding the use of capping agents and preserving the natural chemical reactivity of the pristine surface.