Ligand tethering by ion-exchange for the immobilization of homogeneous catalysts

A Rh phosphine complex, derived from the Wilkinson’s catalyst, has been immobilized by ion-exchange on the ammonium form of a Al-MCM-41 sample. Ammonium ions have been exchanged by cholamine ions, which act as an amine ligand, and then the Wilkinson’s catalyst has been immobilized by substitution of a phosphine ligand by the anchored amine. This is a novel immobilization procedure, as a ligand, instead of the whole complex, is tethered to the support by ion exchange. The obtained hybrid catalyst has been characterized by Elemental Analysis, DRIFTS and XPS. The quantitative exchange of ammonium by cholamine and coordination of Rh to amines has been observed. Most of the anchored Rh is considered to be coordinated to the ligand tethered to the support and a small proportion seems to be interacting with the protonated ligand or with the support surface. The catalyst has been tested in the hydrogenation of cyclohexene and in the hydroformylation of 1-octene. In the first case the catalyst is active and reusable, while a strong Rh leaching takes place in the second one.

Muscle-Type Nicotinic Receptor Blockade by Diethylamine, the Hydrophilic Moiety of Lidocaine

Lidocaine bears in its structure both an aromatic ring and a terminal amine, which can be protonated at physiological pH, linked by an amide group. Since lidocaine causes multiple inhibitory actions on nicotinic acetylcholine receptors (nAChRs), this work was aimed to determine the inhibitory effects of diethylamine (DEA), a small molecule resembling the hydrophilic moiety of lidocaine, on Torpedo marmorata nAChRs microtransplanted to Xenopus oocytes. Similarly to lidocaine, DEA reversibly blocked acetylcholine-elicited currents (IACh) in a dose-dependent manner (IC50 close to 70 μM), but unlike lidocaine, DEA did not affect IACh desensitization. IACh inhibition by DEA was more pronounced at negative potentials, suggesting an open-channel blockade of nAChRs, although roughly 30% inhibition persisted at positive potentials, indicating additional binding sites outside the pore. DEA block of nAChRs in the resting state (closed channel) was confirmed by the enhanced IACh inhibition when pre-applying DEA before its co-application with ACh, as compared with solely DEA and ACh co-application. Virtual docking assays provide a plausible explanation to the experimental observations in terms of the involvement of different sets of drug binding sites. So, at the nAChR transmembrane (TM) domain, DEA and lidocaine shared binding sites within the channel pore, giving support to their open-channel blockade; besides, lidocaine, but not DEA, interacted with residues at cavities among the M1, M2, M3, and M4 segments of each subunit and also at intersubunit crevices. At the extracellular (EC) domain, DEA and lidocaine binding sites were broadly distributed, which aids to explain the closed channel blockade observed. Interestingly, some DEA clusters were located at the α-γ interphase of the EC domain, in a cavity near the orthosteric binding site pocket; by contrast, lidocaine contacted with all α-subunit loops conforming the ACh binding site, both in α-γ and α-δ and interphases, likely because of its larger size. Together, these results indicate that DEA mimics some, but not all, inhibitory actions of lidocaine on nAChRs and that even this small polar molecule acts by different mechanisms on this receptor. The presented results contribute to a better understanding of the structural determinants of nAChR modulation.

Drogas recreativas : o coração do prazer

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

A Comprehensive Discussion of HMBC Pulse Sequences: 4. Establishing Two-Bond Correlations from HMBC and Related Experiments

The utility of the HMBC experiment for structure elucidation is unquestionable, but the nature of the coupling pathways leading to correlations in an HMBC experiment creates the potential for misinterpretation. This misinterpretation potential is intimately linked to the size of the long-range heteronuclear couplings involved, and may become troublesome in those cases of a particularly strong 2JCH correlation that might be mistaken for a 3JCH correlation or a 4JCH correlation of appreciable strength that could be mistaken for a weaker 3JCH correlation. To address these potential avenues of confusion, work from several laboratories has been focused on the development of what might be considered “coupling pathway edited” long-range heteronuclear correlation experiments that are derived from or related to the HMBC experiment. The first example of an effort to address the problems associated with correlation path length was seen in the heteronucleus-detected XCORFE experiment described by Reynolds and co-workers that predated the development of the HMBC experiment. Proton-detected analogs of the HMBC experiment intended to differentiate 2JCH correlations from nJCH correlations where n = 3, 4, include the 2J,3J-HMBC, HMBC-RELAY, H2BC, edited-HMBC, and HAT H2BC experiments. The principles underlying the critical components of each of these experiments are discussed and experimental verification of the results that can be obtained using model compounds are shown. This contribution concludes with a brief discussion of the 1,1-ADEQUATE experiments that provide an alternative means of identifying adjacent protonated and non-protonated carbon correlations by exploiting 1JCC correlations at natural abundance.

Drug and alcohol testing results 2001 annual report.

Statistics on employees returned to duty and results of return-to-duty tests and follow-up tests are presented separately from results of the other four test types because return-to-duty tests and follow-up tests represent a different segment of the test population and not all employers offer rehabilitation.

Erythroxylon coca : a lecture /

Includes bibliographical references.

A comprehensive analysis of sexual dimorphism in the midbrain dopamine system

Thesis (Ph.D.)--University of Washington, 2016-06

Psychoanalytic perspectives on substance use and antisocial personality disorder

Psychoanalysis and related psychodynamic psychotherapies have historically had a limited engagement with substance use and antisocial personality disorders. This in part reflects an early preoccupation with 'transference neuroses' and in part reflects later de-emphasis of diagnosis and focus on therapeutic process. Nonetheless, psychoanalytic perspectives can usefully inform thinking about approaches to treatment of such disorders and there are psychoanalytic constructs that have specific relevance to their treatment. This paper reviews some prominent strands of psychoanalytic thinking as they pertain to the treatment of substance abuse and antisocial personality disorders. It is argued that, while Freudian formulations lead to a primarily pessimistic view of the prospect of treatment of such disorders, both the British object relations and the North American self psychology traditions suggest potentially productive approaches. Finally the limited empirical evidence from brief psycho dynamically informed treatments of substance use disorders is reviewed. It is concluded that such treatments are not demonstrably effective but that, since no form of psychotherapy has established high efficacy with substance use disorders, brief psychdynamic therapies are not necessarily of lesser value than other treatments and may have specific value for particular individuals and in particular treatment contexts.

Roles of transmembrane domain 2 and the first intracellular loop in human noradrenaline transporter function: pharmacological and SCAM analysis

The aim was to investigate the roles of transmembrane domain 2 and the adjacent region of the first intracellular loop in determining human noradrenaline transporter (hNET) function by pharmacological and substituted-cysteine accessibility method (SCAM) analyses. It was first necessary to establish a suitable background NET for SCAM. Alanine mutants of endogenous hNET cysteines, hC86A, hC131A and hC339A, were examined and showed no marked effects on expression or function. hNET and the mutants were also resistant to methanethiosulfonate (MTS), ethylammonium (MTSEA) and MTStrimethylammonium (MTSET). Hence, wild-type hNET is an appropriate background for production of cysteine mutants for SCAM. Pharmacological investigation showed that all mutants except hT99C and hL109C showed reduced cell-surface expression, while all except hM107C showed a reduction in functional activity. The mutations did not markedly affect the apparent affinities of substrates, but apparent affinities of cocaine were decreased 7-fold for hP97C and 10-fold for hF101C and increased 12-fold for hY98C. [H-3]Nisoxetine binding affinities were decreased 13-fold for hP97C and 5-fold for hF101C. SCAM analysis revealed that only hL102C was sensitive to 1.25 mM MTSEA, and this sensitivity was protected by noradrenaline, nisoxetine and cocaine. The results suggest that this region of hNET is important for interactions with antidepressants and cocaine, but it is probably not involved in substrate translocation mechanisms.

The impact of a reduction in drug supply on demand for and compliance with treatment for drug dependence

Background: In early 2001, Australia experienced a sudden, dramatic and;sustained decrease in heroin availability that was accompanied by sharp increases in price and decreases in street level purity-the so-called heroin shortage. These unprecedented changes occurred in a context of widespread treatment availability, which made it possible for the first time to examine the impact of a sharp reduction in heroin supply in New South Wales (NSW) on entry to and adherence with treatment for heroin dependence. Given the evidence of drug substitution by some users. the current paper also examines the effects of the shortage on entry to treatment for other forms of drug dependence. Methods: Interrupted time-series analysis of the number of persons entering opioid pharmacotherapy and other treatment modalities in NSW for heroin dependence and for the treatment for other types of drug dependence. Findings: The heroin shortage was associated with a reduction in the number of younger persons entering opioid pharmacotherapy. There was a dramatic decrease in the number of persons entering heroin withdrawal or assessment only treatment episodes. There appear to have been small improvements in adherence to and retention in heroin treatment after the reduction in heroin supply. Relatively small increases were observed in numbers being treated for cocaine dependence. Conclusions: In the context of good treatment provision, a reduction in heroin supply appeared to produce modest improvements in intermediate outcomes. Supply and demand reduction measures, when both are implemented successfully, may be complementary. (c) 2005 Elsevier Ireland Ltd. All rights reserved.

The effect of a reduction in heroin supply on fatal and non-fatal drug overdoses in New South Wales, Australia

Objective: To examine the impact of a sudden and dramatic decrease in heroin availability, concomitant with increases in price and decreases in purity, on fatal and non-fatal drug overdoses in New South Wales, Australia. Design and setting: Time-series analysis was conducted where possible on data on overdoses collected from NSW hospital emergency departments, the NSW Ambulance Service, and all suspected drug-related deaths referred to the NSW Coroner's court. Main outcome measures: The number of suspected drug-related deaths where heroin and other drugs were mentioned; ambulance calls to suspected opioid overdoses; and emergency department admissions for overdoses on heroin and other drugs. Results: Both fatal and non-fatal heroin overdoses decreased significantly after heroin supply reduced; the reductions were greater among younger age groups than older age groups. There were no clear increases in non-fatal overdoses with cocaine, methamphetamines or benzodiazepines recorded at hospital emergency departments after the reduction in heroin supply. Data on drug-related deaths suggested that heroin use was the predominant driver of drug-related deaths in NSW, and that when heroin supply was reduced overdose deaths were more likely to involve a wider combination of drugs. Conclusion: A reduction in heroin supply reduced heroin-related deaths, and did not result in a concomitant increase, to the same degree, in deaths relating to other drugs. Younger people were more affected by the reduction in supply.