The role of hippocampal estradiol in synaptic plasticity and memory: A systematic review.

The consolidation of long-term memory is influenced by various neuromodulators. One of these is estradiol, a steroid hormone that is synthesized both in peripheral endocrine tissue and in the brain, including the hippocampus. Here, we examine the evidence regarding the role of estradiol in the hippocampus, specifically, in memory formation and its effects on the molecular mechanisms underlying synaptic plasticity. We conclude that estradiol improves memory consolidation and, thereby, long-term memory. Previous studies have shown that it does this in three, interconnected ways: (1) via functional changes in excitatory activity, (2) signaling changes in calcium dynamics, protein phosphorylation and protein expression, and (3) structural changes to synaptic morphology. Through a functional network analysis of proteins affected by estradiol, we identify potential protein-protein interactions that further support a role for estradiol in modulating synaptic plasticity as well as highlight signaling pathways that may be involved in these changes within the hippocampus.

Spatiotemporal evolutionary epidemiology of H5N1 highly pathogenic avian influenza in West Africa and Nigeria, 2006-2015.

H5N1 highly pathogenic avian influenza virus (HPAIV) was first observed in Nigeria in early 2006 and has now spread to more than 17 African countries having severe economic and public health implications. Here, we explore the spatiotemporal patterns of viral dispersal both among West African countries and within Nigeria using sequence data from hemagglutinin (HA) gene region of the virus. Analyses were performed within a statistical Bayesian framework using phylodynamic models on data sets comprising of all publically available HA sequence data collected from seven West African countries and Egypt between 2006 and 2015. Our regional-level analyses indicated that H5N1 in West Africa originated in Nigeria in three geopolitical regions, specifically north central and north-east, where backyard poultry and wild birds are in frequent contact, as well as south-west, a major commercial poultry area, then dispersed to West African countries. We inferred significant virus dispersal routes between Niger and Nigeria on one side and Burkina Faso, Ivory Coast, Ghana and Egypt on the other. Furthermore, south-west Nigeria identified as a primary source for virus dispersal within Nigeria as well as to Niger in 2006 and 2008. Niger was an important epicentre for the virus spread into other West African countries in 2015. Egyptian introductions from West Africa were sporadic and resulted most likely from poultry trade with Nigeria rather than contact with infected wild birds. Our inferred viral dispersal routes reflected the large-scale unrestricted movements of infected poultry in the region. Our study illustrates the ability of phylodynamic models to trace important HPAIV dispersal routes at a regional and national level. Our results have clear implications for the control and prevention of this pathogen across scales and will help improve molecular surveillance of transboundary HPAIVs.

1H, 13C and 15N NMR assignments of the C1A and C1B subdomains of PKC-delta.

The Protein Kinase C family of enzymes is a group of serine/threonine kinases that play central roles in cell-cycle regulation, development and cancer. A key step in the activation of PKC is translocation to membranes and binding of membrane-associated activators including diacylglycerol (DAG). Interaction of novel and conventional isotypes of PKC with DAG and phorbol esters occurs through the two C1 regulatory domains (C1A and C1B), which exhibit distinct ligand binding selectivity that likely controls enzyme activation by different co-activators. PKC has also been implicated in physiological responses to alcohol consumption and it has been proposed that PKCα (Slater et al. J Biol Chem 272(10):6167-6173, 1997; Slater et al. Biochemistry 43(23):7601-7609, 2004), PKCε (Das et al. Biochem J 421(3):405-413, 2009) and PKCδ (Das et al. J Biol Chem 279(36):37964-37972, 2004; Das et al. Protein Sci 15(9):2107-2119, 2006) contain specific alcohol-binding sites in their C1 domains. We are interested in understanding how ethanol affects signal transduction processes through its affects on the structure and function of the C1 domains of PKC. Here we present the (1)H, (15)N and (13)C NMR chemical shift assignments for the Rattus norvegicus PKCδ C1A and C1B proteins.

Paediatric anal endosonography.

PURPOSE: This study was performed to determine the endosonographic features of the anal canal in normal children and to compare these findings with the endosonographic features in children with congenital anorectal malformations. METHODS: Two groups of children were examined by anal endosonography (AES): group 1 ( n=30) were controls, and group 2 ( n=15) were children born with anorectal malformations. RESULTS: In the normal group, the sphincter elements were clearly visualised. The intersphincteric plane produced a double image, which differs from the adult appearance. Of 15 patients who had anorectoplasty, AES identified accurate placement of the neoanus within the sphincters in 13 and slight malposition in two patients. CONCLUSIONS: This study details the endosonographic appearances of the anal canal in healthy children aged from 1 month to 14 years. AES provided useful anatomical detail in patients following anorectoplasty.

Anti-microbial efficacy and mode of action studies on a new zinc/ Triclosan formulation.

OBJECTIVE: To test in vitro the anti-plaque/ antimicrobial efficacy of a new toothpaste formulation containing a 2% zinc citrate/ 0.3% Triclosan anti-microbial system compared with a 0.75% zinc citrate/ 0.3% Triclosan system and where appropriate, against controls of a standard fluoride paste and a 0.3% Triclosan/ 2% copolymer product. METHODS: The anti-metabolic activity was assessed using a range of assays measuring the ability of the active systems to inhibit bacterial glycolysis. The antibacterial/ anti-plaque activity was assessed in an in vitro multispecies biofilm assay. RESULTS: Both zinc formulations were shown to have significantly superior activity at inhibiting glycolysis compared with the 0.3% Triclosan/ 2% copolymer formulation and the standard fluoride paste, particularly in reducing the pH drop after sugar challenge, the new formulation having the greatest activity. Likewise, in the antibacterial assay, both zinc formulations were found to have significantly superior activity over a standard fluoride paste and the 2% zinc citrate/ 0.3% Triclosan formulation was shown to be significantly better than 0.75% zinc citrate/ 0.3% Triclosan formulation. CONCLUSION: These data provide support for the enhanced performance of the 2% zinc citrate/ 0.3% Triclosan formulation.

The effect of a toothpaste containing 2% zinc citrate and 0.3% Triclosan on bacterial viability and plaque growth in vivo compared to a toothpaste containing 0.3% Triclosan and 2% copolymer.

OBJECTIVE: To compare the antimicrobial efficacy and effect on plaque growth of a new silica-based fluoride toothpaste containing 2% zinc citrate/ 0.3% Triclosan with a silica-based fluoride toothpaste containing 0.3% Triclosan/2% copolymer. METHODS: In Study 1, plaque was collected after one week's use of each toothpaste and assessed for bacterial viability, live/ dead ratio and microbial membrane integrity. In study 2, plaque was measured immediately and 18 hours after a single brushing with the specified toothpastes. RESULTS: The 2% zinc citrate/0.3% Triclosan formulation significantly reduced the total number of viable aerobic and anaerobic bacteria (p = 0.0223 and p = 0.0443 respectively) compared to the 0.3% Triclosan/2% copolymer formulation. Both toothpastes increased the bacterial membrane permeability significantly. However, the proportion of live bacteria for the 2% zinc citrate/0.3% Triclosan product was significantly reduced (p < 0.05). Study 2 showed significantly less plaque growth 18 hours after using the 2% zinc citrate/0.3% Triclosan toothpaste compared to the 0.3% Triclosan/2% copolymer toothpaste (p < 0.01). CONCLUSION: Regular use of a fluoride toothpaste containing 2% zinc citrate and 0.3% Triclosan, significantly reduced the viability of plaque bacteria compared to a fluoride toothpaste containing 0.3% Triclosan/ 2% copolymer 12 hours after brushing. In addition, a clinical plaque growth study confirmed that this anti-microbial efficacy leads to a significant reduction in plaque growth.

Factors linked to bacterial vaginosis in nonpregnant women.

OBJECTIVES: The purposes of this study were to test the hypothesis that vaginal douching is linked to bacterial vaginosis in both symptomatic and asymptomatic women and to identify other demographic, reproductive, and lifestyle factors associated with bacterial vaginosis. METHODS: In this cross-sectional study involving 3 clinic sites, 496 nonpregnant women completed a self-administered questionnaire. Their vaginal smears were assessed and cross-validated for bacterial vaginosis. RESULTS: The prevalence of bacterial vaginosis across clinics ranged from 15% to 30%. In analyses restricted to site 1, adjusted odds ratios (ORs) for bacterial vaginosis remained significant for African American women with 13 or fewer years of education (OR = 5.5, 95% confidence interval [CI] = 2.1, 14.5), hormone use within the past 6 months (OR = 0.5, 95% CI = 0.2, 0.8), and vaginal douching within the past 2 months (OR = 2.9, 95% CI = 1.5, 5.6). CONCLUSIONS: Two lifestyle factors emerge as strongly associated with bacterial vaginosis: systemic contraceptives appear protective, whereas douching is linked to an increase in prevalence. The temporal relationship between douching and bacterial vaginosis needs further clarification.

Hypoxic preconditioning induces changes in HIF-1 target genes in neonatal rat brain.

Hypoxic preconditioning induces tolerance to hypoxic-ischemic injury in neonatal rat brain and is associated with changes in gene expression. Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that is strongly induced by hypoxia or the hypoxia-mimetic compound cobalt chloride (CoCl(2)). Hypoxia-inducible factor-1 modulates the expression of several target genes including the glycolytic enzymes, glucose transporter-1 (GLUT-1), and erythropoietin. Recently, HIF-1 expression was shown to increase after hypoxic and CoCl(2) preconditioning in newborn rat brain. To study the involvement of HIF-1 target genes in neonatal hypoxia-induced ischemic tolerance, the authors examined the brains of newborn rats after exposure to hypoxia (8% O(2) for 3 hours) or injection of CoCl(2) (60 mg/kg). Preconditioning with hypoxia or CoCl(2) 24 hours before hypoxia-ischemia afforded a 96% and 76% brain protection, respectively, compared with littermate control animals. Hypoxic preconditioning increased the expression of GLUT-1 mRNA and protein, and of aldolase, phosphofructokinase, and lactate dehydrogenase proteins but not mRNA. This suggests that the modulation of glucose transport and glycolysis by hypoxia may contribute to the development of hypoxia-induced tolerance. In contrast, preconditioning with CoCl(2) did not produce any change in HIF-1 target gene expression suggesting that different molecular mechanisms may be involved in the induction of tolerance by hypoxia and CoCl(2) in newborn brain.

Comparison of methods for extraction of tobacco alkaloids.

Ultrasound and microwave techniques were used to extract tobacco alkaloids, and response surface methodology was used to optimize extraction conditions. Ultrasonic technique factors were temperature, 30-85 degrees C; time, 3-45 min; solvent volume, 8-80 mL. Microwave extraction factors were pressure, 15-75 psi; time, 3-40 min; power, 30-90% of the maximum magnetron power of 650 W. Soxhlet and solvent AOAC-modified extraction methods were also applied after some improvements. Nicotine, nornicotine, anabasine, and anatabine were quantified by gas chromatography. A steam distillation International Standards Organization method for total alkaloid evaluation was used as reference. The results obtained by the different methods were compared using a least squares deviation test. The ultrasonic and the proposed modified-AOAC extraction method were the more convenient with regard to practicability and precision. The relative deviations (n = 5) were as follows: For the ultrasonic method in low-level alkaloid tobaccos, 0.7% nicotine and 1.4-14% minor alkaloids; in high-level alkaloid tobaccos, 2.4% nicotine and 4.5-5.1% minor alkaloids. For the modified AOAC method in low-level alkaloid tobaccos, 0.9% nicotine and 2.4-11.6% minor alkaloids; and in high-level alkaloid tobaccos, 1.7% nicotine and 2.0-2.4% minor alkaloids.

Direct visualization of cholecystokinin subtype2 receptors in rat central nervous system using anti-peptide antibodies.

The cholecystokinin receptor, subtype 2 (CCK(2)R), is considered, based on receptor autoradiography, to be the predominant receptor for this peptide transmitter in the mammalian central nervous system. To directly visualize the CCK(2)R we utilized a convenient and sensitive immunohistochemical procedure using antipeptide receptor antibodies raised in rabbits against unique portions of the carboxyl tail and third intracellular loop of the CCK(2)R. Antibodies were characterized by ELISA and Western blotting, and used for immunohistochemistry in rat brain sections. Studies with both antibodies revealed a widespread topographic distribution of CCK(2)R-like immunoreactivity (CCK(2)R-LI) in regions such as cortex, olfactory bulb, nucleus accumbens, septum, striatum, hippocampus, basolateral amygdala, habenula, hypothalamus, thalamus, ventral mesencephalon, inferior colliculus, parabrachial nucleus, pontine nucleus, supercolliculus, red nucleus, subcommisural and occulomotor nucleus, area postrema, solitary, olivary, cochlear, cuneate and trigeminal nuclei and spinal cord dorsal horn in agreement with the results of previous receptor autoradiography.

Neuroprotective effects of LY379268, a selective mGlu2/3 receptor agonist: investigations into possible mechanism of action in vivo.

The mechanisms underlying the neuroprotective effects of the group II metabotropic glutamate receptor (mGluR) agonist LY379268 were investigated in a gerbil model of global ischemia. LY379268 (10 mg/kg i.p.) 30 or 60 min after 5-min bilateral carotid artery occlusion (BCAO) attenuated the ischemia-induced hyperactivity and provided protection in the CA1 hippocampal cells. This neuroprotective effect was maintained (P <.001) when histological analysis was performed 14 and 28 days after BCAO. Furthermore, 24- or 48-h pretreatment with LY379268, 10 mg/kg i.p., before 5-min BCAO markedly reduced (P <.001 and P <.05, respectively) the damage to CA1 hippocampal neurons. This result is consistent with the induction of neuroprotective factors or a very long brain half-life. To study the possible induction of neuroprotective factors as contributing to this action of LY379268, brains were examined for expression of neurotrophic factors. Results indicated that LY379268 (10 mg/kg i.p.) failed to alter the expression of transforming growth factor-beta, brain-derived neurotrophic factor, nerve growth factor, and basic fibroblast growth factor in the hippocampal regions of brains taken from gerbils sacrificed at 6, 24, 72, and 120 h postinjection. The new group II mGlu antagonist, LY341495, administered 1 h before 5-min BCAO, attenuated the neuroprotective effect of LY379268 administered 24 h before 5-min BCAO. Complementary pharmacokinetic studies showed that a significant receptor-active concentration persisted in the brain 24 h after LY379268 10 mg/kg i.p. We conclude that group II mGluR occupancy, rather than induction of neuroprotective factors, explains the long-lasting neuroprotective effect of LY379268 in the gerbil model of global ischemia.

Type I and II metabotropic glutamate receptor agonists and antagonists evoke cardiovascular effects after intrathecal administration in conscious rats.

1. In the present study, the role of metabotropic glutamate receptors (mGluRs) in central cardiovascular regulation in conscious rats was examined. To this end, agonists and antagonists for type I and II mGluRs were administered intrathecally, and the temporal changes in blood pressure and heart rate were recorded. 2. L-glutamate (1 micromol) and the prototypical mGluR agonist (1S,3R)-ACPD (0.1 and 0. 3 micromol) both increased mean arterial pressure (MAP) and heart rate (HR), implicating functional mGluRs in the spinal cord. The type I mGluR agonist DHPG (0.01 - 0.1 micromol) evoked increases in MAP (max=25+/-5 mmHg) and HR (max=88+/-23 beats min-1). The duration of action, but not the maximum effects, were dose-related and ranged from approximately 10 min to <90 min and 1 min to >90 min for MAP and HR, respectively. 3. The type I/II mGluR agonist CCG-1 (0.1 and 0. 3 micromol) caused smaller, variable increases in MAP and HR of intermediate duration (5 - 20 min), whereas the type II MGluR agonist APDC (0.1 and 1.0 micromol) caused marked, but transient (3 - 5 min), pressor and tachycardic responses. The highest doses of DHPG and CCG-1, but not APDC, also evoked behavioural responses similar to a spontaneous nociceptive behavioural effect reported previously. 4. The type I and II mGluR antagonists (AIDA and LY307452, respectively) were also given approximately 5 min before the administration of the respective type I and II mGluR agonists (DHPG and APDC). Both compounds caused pressor and tachycardic responses, with the effect of AIDA, but not LY307452, returning to control levels before mGluR agonist administration. AIDA significantly attenuated the overall cardiovascular effects of DHPG, while LY307452 significantly attenuated the overall cardiovascular effects of APDC. 5. These results indicate that functional type I and II mGluRs exist in the spinal cord, and that their activation evokes prolonged cardiovascular effects.

Type I and II metabotropic glutamate receptors mediate depressor and bradycardic actions in the nucleus of the solitary tract of anaesthetized rats.

The potential role of metabotropic glutamate (mGlu) receptors in cardiovascular function in the nucleus of the solitary tract was examined following the microinjection of a number of selective mGlu receptor compounds into this site of anaesthetized rats. The prototypic mGlu receptor selective agonist 1S,3R-1-amino-cyclopentane dicarboxylate elicited depressor and bradycardic actions following microinjection into the nucleus tractus solitarius, which were similar to those produced by L-glutamate. Similarly, decreases in blood pressure and heart rate were observed upon administration of the type I and II selective mGlu receptor agonists, (R,S)-3,5-dihydroxyphenylglycine (DHPG) and 2R,4R-4-aminopyrrolidine-2,4-dicarboxylate (APDC), respectively. These actions of DHPG were selectively attenuated by (+/-)-1-aminoindane-1,5-dicarboxylate, a type I mGlu receptor antagonist, whilst cardiovascular responses to APDC were unaffected by this compound. Interestingly, the proposed type II antagonist, (2S,4S)-2-amino-4-(4,4-diphenylbut-1-yl)-pentane-1,5-doic acid, reduced the cardiovascular responses to intra-nucleus tractus solitarius administration of both APDC and DHPG. The type III mGlu receptor agonist, L-2-amino-4-phosphonobutyrate, however, failed to elicit any cardiovascular actions when microinjected into the nucleus tractus solitarius. These studies provide new evidence for functional type I and II mGlu receptors in modulating cardiovascular responses in the nucleus tractus solitarius.

Type I and II metabotropic glutamate receptors regulate the outflow of [3H]D-aspartate and [14C]gamma-aminobutyric acid in rat solitary nucleus.

Metabotropic glutamate (mGlu) receptors modulating amino acid outflow were examined in a model system in order to further characterize the pharmacological nature of the mGlu receptors involved in viscerosensory processing in the nucleus tractus solitarii. The actions of a number of subtype-selective mGlu receptor agonists and antagonists were monitored on the K+-evoked outflow of [3H]D-aspartate and [14C]gamma-aminobutyric acid (GABA) from superfused slices of rat nucleus tractus solitarii. (+/-)1S,3R-1-Amino-cyclopentane-1,3-dicarboxylate (10-300 microM), produced a concentration-dependent increase in outflow, which was attenuated by a number of phenylglycine antagonists. (2S,3S,4S)-alpha-(Carboxycyclopropyl)-glycine (30-300 microM) had mixed effects on outflow. The type I-selective agonist (RS)-3,5-dihydroxyphenylglycine (300 microM) also increased outflow and these effects were reversed by the type I antagonist (RS)-1-aminoindan-1,5-dicarboxylate (100 microM). Activation of type II mGlu receptors with (2R,4R)-aminopyrrolidine-2,4-dicarboxylate (300 microM), however, decreased outflow, and this effect was antagonized by the type II antagonist LY307452 (200 microM). Interestingly, LY307452 (200 microM) alone, enhanced outflow of [3H]D-aspartate, but not [14C]GABA. Type III mGlu receptors may not be involved in outflow of [3H]D-aspartate and [14C]GABA in the nucleus tractus solitarii, as L-2-amino-4-phosphonobutyrate (30-300 microM) had no effect under the present experimental conditions. These in vitro studies provide new evidence for roles for Type I and II mGlu receptors in viscerosensory processing in nucleus tractus solitarii.

In vivo microdialysis reveals facilitatory metabotropic glutamate receptors regulating excitatory amino acid release in rat nucleus tractus solitarius.

The functional involvement of metabotropic glutamate receptors in nucleus tractus solitarius of the medulla has been examined by evaluating the action of the selective metabotropic glutamate receptor agonist trans-1-amino-cyclopentane-1,3-dicarboxylate on the extracellular release of L-glutamate and L-aspartate by in vivo microdialysis. Studies were performed in urethane anaesthetized rats, with a microdialysis probe being inserted into the medial nucleus tractus solitarius, which was constantly perfused with artificial cerebrospinal fluid (1 microliter/min). Following an equilibration period, samples were collected for amino acid analysis by HPLC. trans-1-Amino-cyclopentane-1,3-dicarboxylate (30 microM) produced 190% and 500% increases in basal release of L-glutamate and L-aspartate, respectively. trans-1-Amino-cyclopentane-1,3-dicarboxylate-evoked release of L-glutamate and L-aspartate was concentration-dependent (10-100 microM), and was calcium and tetrodotoxin-sensitive. Two metabotropic glutamate receptor antagonists, (+)-alpha-methyl-4-carboxyphenylglycine (200 microM) and (S)-4-carboxyphenylglycine (500 microM), when administered via a microdialysis probe, significantly attenuated the trans-1-amino-cyclopentane-1,3-dicarboxylate-evoked release of both L-glutamate and L-aspartate. Basal release was not altered by these two antagonists. Histological studies verified the location of the probe in the nucleus tractus solitarius. These studies provide the first evidence using in vivo microdialysis of functional metabotropic glutamate receptors, which seem to be facilitatory pre- and postsynaptically located receptors, in the rat nucleus tractus solitarius. On the basis of our findings, metabotropic glutamate receptors are likely to play key modulatory roles in regulating transmitter release.

Comparison of outcome measures for patients with chronic obstructive pulmonary disease (COPD) in an outpatient setting.

BACKGROUND: To assist clinicians and researchers in choosing outcome measures for patients with chronic obstructive pulmonary disease attending routine outpatient clinics, a comparative assessment was undertaken of four questionnaires designed to reflect the patients' perception of their physical and emotional health in terms of their feasibility, validity, reliability, and responsiveness to health change. METHODS: Two condition specific questionnaires, the St George's Respiratory Questionnaire (SGRQ) and Guyatt's Chronic Respiratory Questionnaire (CRQ), and two generic questionnaires, the Short Form-36 Health Survey (SF-36) and Euroqol (EQ), were compared for their discriminative and evaluative properties. Spirometric tests and a walking test were also performed. One hundred and fifty six adults who were clinically judged to have COPD and who attended an outpatient chest clinic were assessed at recruitment and six and 12 months later. Patients were also asked whether their health had changed since their last assessment. RESULTS: Completion rates and consistency between items for dimensions of the SGRQ were lower than for dimensions of the other questionnaires. The distributions of responses were skewed for certain dimensions in all questionnaires except the CRQ. Validity was supported for all instruments insofar as patients' scores were associated with differences in disease severity. The generic questionnaires better reflected other health problems. All instruments were reliable over time. The condition specific questionnaires were more responsive between baseline and first follow up visit but this difference did not persist. While certain dimensions of the SF-36 were responsive to patient perceived changes, this did not apply to the derived single index of the EQ. The rating scale of the EQ, however, provided a quick and easy indicator of change. CONCLUSIONS: Evidence from this study supports the CRQ and the SF-36 as comprehensive outcome measures for patients with longstanding COPD.

Roles for nitric oxide as an intra- and interneuronal messenger at NMDA release-regulating receptors: evidence from studies of the NMDA-evoked release of [3H]noradrenaline and D-[3H]aspartate from rat hippocampal slices.

N-Methyl-D-aspartate (NMDA) receptors regulating the release of [3H]noradrenaline ([3H]NA) and D-[3H]aspartate (D-[3H]Asp) were investigated in superfused slices of rat hippocampus in the presence and absence of nitrergic drugs to examine a possible role for nitric oxide (NO) in the release process. In Mg(2+)-free Krebs-Henseleit buffer, the NMDA-evoked release of [3H]NA and D-[3H]Asp was Ca2+ dependent and inhibited by the NMDA antagonist (+/-)-3-(2-carboxypiperazin-4-yl)propenyl-1-phosphonic acid. NMDA-stimulated release of [3H]NA was tetrodotoxin (TTX; 0.1-2 microM) sensitive, whereas that for D-[3H]Asp was TTX insensitive, indicating that the NMDA receptors involved are differentially localized; those for D-[3H]Asp appear to be presynaptic, whereas those for [3H]NA are extrasynaptic in location. L-Arginine (100 microM), the natural precursor of NO synthesis, enhanced NMDA-evoked release of [3H]NA (100%) and D-[3H]Asp (700%). Exogenous NO donors--sodium nitroprusside, 3-morpholinosyndnomine, and S-nitroso-N-acetylpenicillamine (all 100 microM)--stimulated the NMDA-evoked release. An exception was the inhibition by nitroprusside of NMDA-evoked release of [3H]NA, where the presence of antioxidants may influence channel activity. Inhibitors of NO synthase (NG-nitro-, NG-methyl-, and NG-amino-L-arginine, all 100 microM) attenuated (50-80%) the NMDA-stimulated release of [3H]NA and D-[3H]Asp, as did KN-62 (10 microM), a specific inhibitor of calmodulin kinase II. Our data support roles for the NO transducing system subsequent to the activation of NMDA release-regulating receptors as both an intraneuronal (presynaptically) and an extraneuronal messenger.

Complex involvement of nitric oxide and cGMP at N-methyl-D-aspartic acid receptors regulating gamma-[3H]aminobutyric acid release from striatal slices.

Whilst the depolarization of postsynaptic N-methyl-D-aspartic acid (NMDA) receptors leads to an influx of Ca2+ and subsequent synthesis of nitric oxide (NO), we examined roles for NO at striatal NMDA receptors regulating transmitter release. In superfused rat striatal slices, NMDA-evoked release of gamma-[3H]aminobutyric acid ([3H]GABA) was investigated in the presence of nitrergic drugs. NMDA-induced release of [3H]GABA was attenuated by D-2-aminophosphonopentanoate, tetrodotoxin and omission of Ca2+. L-Arginine enhanced NMDA-evoked release of [3H]GABA, but exogenous NO donors were ineffective. Inhibitors of NO synthase (NG-nitro- and NG-amino-L-arginine) and guanylate cyclase (LY83583) elevated release. Since NMDA-evoked release of [3H]GABA was partially tetrodotoxin-sensitive, nitrergic-linked NMDA receptors regulating the release are both pre- and extrasynaptic. Thus not only does NO arise from multiple sites, and involve NMDA receptors with their redox site insensitive to exogenous NO donors, but the NMDA receptors are under the influence of nitrergic and cGMP-linked negative feedback mechanisms.

A meta-analysis of clinical trials involving different classifications of response into ordered categories.

Statistical methods are available for performing a meta-analysis when the response variable of interest is the same in each study. Problems arise when studies exploring a common therapeutic question use different patient response types. This article presents statistical methods for combining studies which involve different classifications of response into ordered categories. The assumptions required for the stratified proportional odds model, on which the analysis is based, are discussed. The approach is illustrated using results from a series of studies investigating the prevention of gastrointestinal damage induced by non-steroidal anti-inflammatory drugs.

Diverse roles for nitric oxide in synaptic signalling after activation of NMDA release-regulating receptors.

NMDA receptors regulating transmitter release were studied in three model systems to investigate whether their activation involves the NO transduction system. In superfused slices of rat brain, the release of [3H]D-aspartate, [3H]noradrenaline and [3H]GABA evoked by NMDA could be modulated by nitrergic drugs. Tetrodotoxin (0.1 microM) exerted differential effects in the three systems indicative of the NMDA receptors (and hence sites of NO generation) being pre- or extra-synaptic, or a combination of both types of localization. L-Arginine (100 microM) enhanced NMDA-evoked release of [3H]GABA (110%), [3H]NA (120%) and [3H]D-ASP (700%). Exogenous NO donors could increase NMDA-induced release of [3H]NA and [3H]D-ASP from hippocampal slices, although differential effects were noted, whilst inhibitors of NO synthase (NG-nitro- and NG-amino-L-arginine, both 100 microM) attenuated (60-85%) the release. NMDA-evoked release of [3H]GABA from striatal slices were insensitive to exogenous NO donors, but NG-nitro- and NG-amino-L-arginine produced 100% increases. In all cases, the NMDA receptors regulating release are linked to a NO system, although the link to the receptors modulating release of [3H]GABA appeared different. The actions of the nitrergic drugs may depend upon the redox state and/or cellular milieu of the individual NMDA receptors involved.