alpha4beta2 nicotinic receptors with high and low acetylcholine sensitivity: pharmacology, stoichiometry, and sensitivity to long-term exposure to nicotine

alpha4 and beta2 nicotinic acetylcholine receptor (nAChR) subunits expressed heterologously assemble into receptors with high (HS) and low (LS) sensitivity to acetylcholine (ACh); their relative proportions depend on the alpha4to beta2 ratio. In this study, injection of oocytes with 1:10 alpha4/beta2 subunit cDNA ratios favored expression of HS alpha4beta2 nAChRs, as evidenced by monophasic ACh concentration-response curves, whereas injections with 10:1 cDNA ratios favored expression of LS alpha4beta2 receptors. The stoichiometry was inferred from the shifts in the ACh EC(50) values caused by Leu to Thr mutations at position 9' of the second transmembrane domain of alpha4 and beta2. The 1:10 injection ratio produced the (alpha4)(2)(beta2)(3) stoichiometry, whereas 10:1 injections produced the (alpha4)(3)(beta2)(2) stoichiometry. The agonists epibatidine, 3-[2(S)-azetidinylmethoxy]pyridine (A-85380), 5-ethoxy-metanicotine (TC-2559), cytisine, and 3-Br-cytisine and the antagonists dihydro-beta-erythroidine and d-tubocurarine were more potent at HS receptors. TC-2559 was more efficacious than ACh at HS receptors but was a partial agonist at LS receptors. Epibatidine was more efficacious than ACh at LS receptors and a partial agonist at HS receptors. Cytisine and 5-halogenated cytisines had moderate efficacy at LS receptors but had almost no efficacy at HS receptors. By exploiting the differential effects of ACh, TC-2559 and 5-I-cytisine we evaluated the effects of long-term exposure to nicotine on HS and LS receptors expressed in Xenopus laevis oocytes after cDNA injections or microtransplantation of alpha4beta2 receptors assembled in human embryonic kidney 293 cells. We conclude that nicotine up-regulates HS alpha4beta2 receptors, probably by influencing the assembly of receptors rather than by altering the functional state of LS alpha4beta2 nAChRs.     

The PDLIM5 gene and lithium prophylaxis: An association and gene expression analysis in Sardinian patients with bipolar disorder

A number of studies support the notion that lithium interacts with the protein kinase C (PKC) pathway, an important mediator of several intracellular responses to neurotransmitter signaling. PDLIM5 (PDZ and LIM domain 5; LIM) is an adaptor protein that selectively binds the isozyme PKC(epsilon) to N-type Ca(2+) channels in neurons. We tested for an association between three single nucleotide polymorphisms (SNPs) at the PDLIM5 gene and lithium prophylaxis in a Sardinian sample comprised of 155 bipolar patients treated with lithium. In order to evaluate whether PDLIM5 expression interacts with lithium response, we carried out gene expression analysis in lymphoblastoid cells of 30 bipolar patients. No association was shown between PDLIM5 polymorphisms and lithium response. When PDLIM5 expression was evaluated, no significant differences were detected between Full Responders to lithium (total score>or=7) and other patients (total score相似文献   

Development and validation of a LC-MS method with electrospray ionization for the determination of the imidazole H3 antagonist ROS203 in rat plasma

A rapid, simple and sensitive liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for the determination of the imidazole H(3) antagonist ROS203 in rat plasma, using the superior homologue ROS287 as internal standard. Analyses were performed on an Agilent 1100 Series HPLC system employing a Supelco Ascentis C(18) column and isocratic elution with acetonitrile-10mM ammonium acetate buffer pH 4.0 (30:70, v/v) at a flow rate of 0.25 mL/min. An Applied Biosystems/MDS Sciex 150-EX single quadrupole mass spectrometer, equipped with an electrospray ionization interface was employed, operating in the positive ion mode. Plasma samples were deproteinized with acetonitrile (1:2), evaporated under nitrogen stream, reconstituted in the mobile phase and 5 microL were injected into the system. The retention times of ROS203 and IS were 2.20 and 2.90 min, respectively. Calibration curves in spiked plasma were linear over the concentration range of 2610-2.61 ng/mL with determination coefficients >0.99. The lower limit of quantification (LLOQ) was 2.61 ng/mL. The accuracy of the method was within 15%. Intra- and inter-day relative standard deviations were less or equal to 9.50% or 7.19%, respectively. The applicability of the LC-MS method was tested employing plasma samples obtained after i.p. administration of ROS203 to female Wistar rats to support a behavioral in vivo study. The specificity of the method was confirmed by the absence of interferences from endogenous substances. The reported method can provide the necessary sensitivity, linearity, precision, accuracy and specificity to allow the determination of ROS203 in rat plasma samples to support further pharmacokinetic assays.     

Neuropharmacological evaluation of diethylether extract and xanthones of Gentiana kochiana

Diethylether extract of aerial parts of Gentiana kochiana mostly consists of two tetraoxygenated xanthones: gentiacaulein (1,7-dihidroxy-3,8-dimethoxyxanthone; 76.1%) and gentiakochianin (1,7,8-trihidroxy-3-methoxyxanthone; 14.2%). The extract and these xanthones were evaluated for the CNS pharmacological activity in rodents. In vitro assays on rat brain preparations revealed insignificant interaction of the compounds with the specific dopamine and serotonin receptors or synaptosomal uptake of serotonin. However, the extract and gentiacaulein strongly inhibited rat microsomal MAO A (IC50=0.22 microg/ml and 0.49 microM, respectively). Their effects on MAO B and a gentiakochianin blocking potential on both MAO enzymes were moderate. Behavioral examinations on mice showed that 10 day s.c. administration of the extract (20 mg/kg) significantly decreased immobility score in a forced swimming test and strongly inhibited ambulation and stereotypy in an open-field test. These effects resembled those induced by 10 mg/kg imipramine. The ex vivo MAO A activity in crude brain mitochondrial fraction of mice treated with 20 mg/kg of the extract was significantly elevated, whilst that outside brain nerve terminals was declined. This study suggests some antidepressant therapeutic potential of G. kochiana, particularly of gentiacaulein, with an ambiguity whether pharmacological mechanism could be related only to the central inhibition of MAO A.     

Reporting adverse drug reactions on a geriatric ward: a pilot project

OBJECTIVE: To test a method for registration of adverse drug reactions (ADRs) resulting in hospital admission and of ADRs occurring during hospital stay. Spontaneous reporting was compared with data from patient interview. METHODS: Spontaneous reporting of ADRs by nurses and physicians, as well as patient interviews by pharmacists. This pilot project was carried out in the geriatric ward of the Ghent University Hospital over a period of 8 months in order to develop suitable registration forms and to test feasibility. Causality, severity, type and level of intervention of the reported ADRs were analysed. Reports from physicians and nurses were compared with the data obtained by patient interviews. RESULTS: During the 8 months, for 168 patients, 12 spontaneous reports were received from physicians and nurses. Fifty-six of these patients were interviewed and 32 ADRs were reported. Only 2 ADRs detected by patient interview were also reported spontaneously. The interviews of the 56 geriatric patients indicated that 20% of them were admitted to the hospital because of an ADR. ADRs occurred during hospital stay in another 20% of those patients. CONCLUSION: Spontaneous reporting by physicians and nurses revealed considerably fewer ADRs than patient interview by pharmacists. Physicians and nurses reported the more serious ADRs that occurred during hospital stay, whereas the interviews revealed more ADRs that caused hospital admission. Our data confirm that ADRs are an important cause of hospital admission of geriatric patients and occur frequently during their hospital stay.     

Twenty years after Spinnler and Tognoni: new instruments in the Italian neuropsychologist’s toolbox

The aim of this article is to review neuropsychological normative studies which - after Spinnler and Tognoni's monograph of 1987 - were done on healthy Italian adult subjects, and which either wholly or partially used the Equivalent Scores (ES) methodology proposed by Capitani et al. The independent norms settled for the same tests have been compared in order to point out their agreement, measured by Cohen's Kappa, which in most cases resulted either excellent or good (>0.7). Available tests have been classified and arranged to facilitate the most suitable choice for different clinical purposes. Moreover, a simple software program has been set up which adjusts and transforms raw scores into ES. As well as saving time and avoiding errors, this simple aid is likely to improve the quality and clarity of the communication of neuropsychological results.     

Analysis of protease inhibitor combinations in vitro: activity of lopinavir, amprenavir and tipranavir against HIV type 1 wild-type and drug-resistant isolates

Background: Despite the increasing number of antiretroviral compounds, the number of useful drug regimens is limited owing to the high frequency of cross-resistance. PATIENTS AND METHODS: We studied in vitro two-drug combinations using three protease inhibitors (PIs), tipranavir, amprenavir and lopinavir, on isolates (003 and 004) derived from patients with resistance to multiple PIs compared with the drug-susceptible isolate 14aPre in peripheral blood mononuclear cells. Drug interactions were determined by median dose-effect analysis, with the combination index calculated at several inhibitory concentrations (IC). RESULTS: In 14aPre experiments, the combination tipranavir + lopinavir demonstrated synergy at low concentrations (IC(50)), an additive effect at IC(75) and antagonism at IC(90)-IC(95); tipranavir + amprenavir were antagonistic at all concentrations except IC(95), where they were synergic; and the lopinavir + amprenavir combination was always antagonistic. In 003 and 004 infections, tipranavir + lopinavir and tipranavir + amprenavir combinations were antagonistic, and lopinavir + amprenavir were synergic, at all concentrations, with the exception of being additive at IC(95). CONCLUSIONS: Our in vitro experiments did not show any advantage in combining second generation PIs as a therapeutic strategy in naive or multi-treatment failure subjects, with the exception of tipranavir + amprenavir at IC(95) in infections by a wild-type isolate.     

Impaired renal Na(+) retention in the sgk1-knockout mouse

The serum- and glucocorticoid-regulated kinase (sgk1) is induced by mineralocorticoids and, in turn, upregulates heterologously expressed renal epithelial Na(+) channel (ENaC) activity in Xenopus oocytes. Accordingly, Sgk1 is considered to mediate the mineralocorticoid stimulation of renal ENaC activity and antinatriuresis. Here we show that at standard NaCl intake, renal water and electrolyte excretion is indistinguishable in sgk1-knockout (sgk1(-/-)) mice and wild-type (sgk1(+/+)) mice. In contrast, dietary NaCl restriction reveals an impaired ability of sgk1(-/-) mice to adequately decrease Na(+) excretion despite increases in plasma aldosterone levels and proximal-tubular Na(+) and fluid reabsorption, as well as decreases in blood pressure and glomerular filtration rate.