BNC210, a negative allosteric modulator of the alpha 7 nicotinic acetylcholine receptor, demonstrates anxiolytic- and antidepressant-like effects in rodents.

This work describes the characterization of BNC210 (6-[(2,3-dihydro-1H-inden-2-yl)amino]-1-ethyl-3-(4-morpholinylcarbonyl)-1,8-naphthyridin-4(1H)-one), a selective, small molecule, negative allosteric modulator (NAM) of α7 nicotinic acetylcholine receptors (α7 nAChR). With the aim to discover a non-sedating, anxiolytic compound, BNC210 was identified during phenotypic screening of a focused medicinal chemistry library using the mouse Light Dark (LD) box to evaluate anxiolytic-like activity and the mouse Open Field (OF) (dark) test to detect sedative and/or motor effects. BNC210 exhibited anxiolytic-like activity with no measurable sedative or motor effects. Electrophysiology showed that BNC210 did not induce α7 nAChR currents by itself but inhibited EC80 agonist-evoked currents in recombinant GH4C1 cell lines stably expressing the rat or human α7 nAChR. BNC210 was not active when tested on cell lines expressing other members of the cys-loop ligand-gated ion channel family. Screening over 400 other targets did not reveal any activity for BNC210 confirming its selectivity for α7 nAChR. Oral administration of BNC210 to male mice and rats in several tests of behavior related to anxiety- and stress- related disorders, demonstrated significant reduction of these behaviors over a broad therapeutic range up to 500 times the minimum effective dose. Further testing for potential adverse effects in suitable rat and mouse tests showed that BNC210 did not produce sedation, memory and motor impairment or physical dependence, symptoms associated with current anxiolytic therapeutics. These data suggest that allosteric inhibition of α7 nAChR function may represent a differentiated approach to treating anxiety- and stress- related disorders with an improved safety profile compared to current treatments.

Cholinergic modulation of disorder-relevant human defensive behaviour in generalised anxiety disorder.

Drugs that are clinically effective against anxiety disorders modulate the innate defensive behaviour of rodents, suggesting these illnesses reflect altered functioning in brain systems that process threat. This hypothesis is supported in humans by the discovery that the intensity of threat-avoidance behaviour is altered by the benzodiazepine anxiolytic lorazepam. However, these studies used healthy human participants, raising questions as to their validity in anxiety disorder patients, as well as their generalisability beyond GABAergic benzodiazepine drugs. BNC210 is a novel negative allosteric modulator of the alpha 7 nicotinic acetylcholine receptor and we recently used functional Magnetic Resonance Imaging to show it reduced amygdala responses to fearful faces in generalised anxiety disorder patients. Here we report the effect of BNC210 on the intensity of threat-avoidance behaviour in 21 female GAD patients from the same cohort. We used the Joystick Operated Runway Task as our behavioural measure, which is a computerised human translation of the Mouse Defense Test Battery, and the Spielberger state anxiety inventory as our measure of state affect. Using a repeated-measures, within-subjects design we assessed the effect of BNC210 at two dose levels versus placebo (300 mg and 2000 mg) upon two types of threat-avoidance behaviour (Flight Intensity and Risk Assessment Intensity). We also tested the effects of 1.5 mg of the benzodiazepine lorazepam as an active control. BNC210 significantly reduced Flight Intensity relative to placebo and the low dose of BNC210 also significantly reduced self-reported state anxiety. Risk Assessment Intensity was not significantly affected. Results show both human defensive behaviour and state anxiety are influenced by cholinergic neurotransmission and there provide converging evidence that this system has potential as a novel target for anxiolytic pharmacotherapy.

Pharmacological Characterization of the Novel and Selective α7 Nicotinic Acetylcholine Receptor-Positive Allosteric Modulator BNC375.

Treatments for cognitive deficits associated with central nervous system (CNS) disorders such as Alzheimer disease and schizophrenia remain significant unmet medical needs that incur substantial pressure on the health care system. The α7 nicotinic acetylcholine receptor (nAChR) has garnered substantial attention as a target for cognitive deficits based on receptor localization, robust preclinical effects, genetics implicating its involvement in cognitive disorders, and encouraging, albeit mixed, clinical data with α7 nAChR orthosteric agonists. Importantly, previous orthosteric agonists at this receptor suffered from off-target activity, receptor desensitization, and an inverted U-shaped dose-effect curve in preclinical assays that limit their clinical utility. To overcome the challenges with orthosteric agonists, we have identified a novel selective α7 positive allosteric modulator (PAM), BNC375. This compound is selective over related receptors and potentiates acetylcholine-evoked α7 currents with only marginal effect on the receptor desensitization kinetics. In addition, BNC375 enhances long-term potentiation of electrically evoked synaptic responses in rat hippocampal slices and in vivo. Systemic administration of BNC375 reverses scopolamine-induced cognitive deficits in rat novel object recognition and rhesus monkey object retrieval detour (ORD) task over a wide range of exposures, showing no evidence of an inverted U-shaped dose-effect curve. The compound also improves performance in the ORD task in aged African green monkeys. Moreover, ex vivo 13C-NMR analysis indicates that BNC375 treatment can enhance neurotransmitter release in rat medial prefrontal cortex. These findings suggest that α7 nAChR PAMs have multiple advantages over orthosteric α7 nAChR agonists for the treatment of cognitive dysfunction associated with CNS diseases. SIGNIFICANCE STATEMENT: BNC375 is a novel and selective α7 nicotinic acetylcholine receptor (nAChR) positive allosteric modulator (PAM) that potentiates acetylcholine-evoked α7 currents in in vitro assays with little to no effect on the desensitization kinetics. In vivo, BNC375 demonstrated robust procognitive effects in multiple preclinical models across a wide exposure range. These results suggest that α7 nAChR PAMs have therapeutic potential in central nervous system diseases with cognitive impairments.

Cholinergic Modulation of Disorder-Relevant Neural Circuits in Generalized Anxiety Disorder.

BACKGROUND: Generalized anxiety disorder is associated with hyperactivity in the amygdala-prefrontal networks, and normalization of this aberrant function is thought to be critical for successful treatment. Preclinical evidence implicates cholinergic neurotransmission in the function of these systems and suggests that cholinergic modulation may have anxiolytic effects. However, the effects of cholinergic modulators on the function of anxiety-related networks in humans have not been investigated. METHODS: We administered a novel α7 nicotinic acetylcholine receptor-negative allosteric modulator, BNC210, to 24 individuals (3 male subjects) with generalized anxiety disorder and assessed its effects on neural responses to fearful face stimuli. RESULTS: BNC210 reduced amygdala reactivity to fearful faces relative to placebo and similarly to lorazepam and also reduced connectivity between the amygdala and the anterior cingulate cortex, a network involved in regulating anxious responses to aversive stimuli. CONCLUSIONS: These results demonstrate for the first time that the function of disorder-relevant neural circuits in generalized anxiety disorder can be beneficially altered through modulation of cholinergic neurotransmission and suggest potential for this system as a novel target for anxiolytic pharmacotherapy.

Discovery of BNC375, a Potent, Selective, and Orally Available Type I Positive Allosteric Modulator of α7 nAChRs.

Positive allosteric modulators (PAMs) of α7 nAChRs can have different properties with respect to their effects on channel kinetics. Type I PAMs amplify peak channel response to acetylcholine but do not appear to influence channel desensitization kinetics, whereas Type II PAMs both increase channel response and delay receptor desensitization. Both Type I and Type II PAMs are reported in literature, but there are limited reports describing their structure-kinetic profile relationships. Here, we report a novel class of compounds with either Type I or Type II behavior that can be tuned by the relative stereochemistry around the central cyclopropyl ring: for example, (R,R)-13 (BNC375) and its analogues with RR stereochemistry around the central cyclopropyl ring are Type I PAMs, whereas compounds in the same series with SS stereochemistry (e.g., (S,S)-13) are Type II PAMs as measured using patch-clamp electrophysiology. Further fine control over the kinetics has been achieved by changing the substitutions on the aniline ring: generally the substitution of aniline with strong electron withdrawing groups reduces the Type II character of these compounds. Our structure-activity optimization efforts have led to the discovery of BNC375, a small molecule with good CNS-drug like properties and clinical candidate potential.

A randomized, controlled pilot study of the effects of vitamin D supplementation on balance in Parkinson's disease: Does age matter?

OBJECTIVES: To explore if short term, high dose vitamin D supplementation is safe and improves balance in persons with Parkinson's disease (PD). METHODS: A pilot randomized, double-blind intervention trial to measure the effects of 16 weeks of high dose vitamin D (10,000 IU/day) on balance as well as other motor and non-motor features of PD. We measured balance, gait, strength, falls, cognition, mood, PD severity, and quality of life before and after 16 weeks of high dose vitamin D supplementation or placebo. All participants also received 1000 mg calcium once daily. RESULTS: Fifty-one randomized participants completed sixteen weeks of high dose vitamin D supplementation or placebo. The intervention resulted in a rise in serum concentrations of vitamin D (25-OH) (30.2 ng/ml to 61.1 ng/ml) and was well tolerated with no serious adverse events. Serum vitamin D (25-OH) levels rose steadily and did not suggest a leveling off at the end of the 16 weeks. There was not an improvement in the primary endpoint, balance as measured by the Sensory Organization Test (p = 0.43). A post hoc analysis examining treatment effects in younger (ages 52-66) versus older (ages 67-86) participants found a significant improvement in the SOT of 10.6 points in the younger half of the cohort (p = 0.012). CONCLUSIONS: Short term, high dose vitamin D supplementation appears safe in persons with PD, but did not significantly improve balance as measured with the Sensory Organization Test in this pilot study population. A post hoc analysis suggests that vitamin D may have potential for improving balance in a younger population with PD. High dose vitamin D supplementation in PD needs further study especially in light of new research suggesting that mega doses and even moderate doses (as low as 4000IU a day) may increase falls in an older populations. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01119131.

Galantamine is not a positive allosteric modulator of human α4ß2 or α7 nicotinic acetylcholine receptors.

BACKGROUND AND PURPOSE: The alkaloid galantamine was originally isolated from the green snowdrop Galanthus woronowii and is currently marketed as a drug for treatment of mild to moderate dementia in patients with Alzheimer's disease. In addition to a well-documented proficiency to inhibit acetylcholinesterase, galantamine has been reported to increase neuronal nicotinic ACh (nACh) receptor function by acting as a positive allosteric modulator. Yet there remains controversy regarding these findings in the literature. To resolve this conundrum, we evaluated galantamine actions at α4ß2 and α7, which represent the nACh receptors most commonly associated with mammalian cognitive domains. EXPERIMENTAL APPROACH: α4ß2 [in (α4)3 (ß2)2 and (α4)2 (ß2)3 stoichiometries] and α7 nACh receptors were expressed in Xenopus laevis oocytes and subjected to two-electrode voltage-clamp electrophysiological experiments. Galantamine (10 nM to 100 µM) was evaluated for direct agonist effects and for positive modulation by co-application with sub-maximally efficacious concentrations of ACh. In addition, similar experiments were performed with α7 nACh receptors stably expressed in HEK293 cells using patch-clamp electrophysiology. KEY RESULTS: In concentrations ranging from 10 nM to 1 µM, galantamine did not display direct agonism nor positive modulatory effects at any receptor combination tested. At concentrations from 10 µM and above, galantamine inhibited the activity with a mechanism of action consistent with open-channel pore blockade at all receptor types. CONCLUSION AND IMPLICATIONS: Based on our data, we conclude that galantamine is not a positive allosteric modulator of α7 or α4ß2 receptors, which represent the majority of nACh receptors in mammalian brain.

A perspective on the contribution of animal models to the pharmacological treatment of posttraumatic stress disorder.

OBJECTIVES: Posttraumatic stress disorder (PTSD) is a prevalent, chronic, disabling disorder that may develop following exposure to a traumatic event. This review summarizes currently used animal models of PTSD and their potential role in the development of better therapeutics. Heterogeneity is one of the main characteristics of PTSD with the consequence that many pharmacological approaches are used to relieve symptoms of PTSD. To address the translational properties of the animal models, we discuss the types of stressors used, the rodent correlates of human PTSD (DSM-5) symptoms, and the efficacy of approved, recommended and off-label drugs used to treat PTSD in 'PTSD-animals'. CONCLUSIONS: Currently available animal models reproduce most PTSD symptoms and are validated by existing therapeutics. However, novel therapeutics are needed for this disorder as not one drug alleviates all symptoms and many have side effects that lead to non-compliance among PTSD patients. The true translational power of animal models of PTSD will only be demonstrated when new therapeutics acting through novel mechanisms become available for clinical practice.

Structure-activity relationship studies of SEN12333 analogues: determination of the optimal requirements for binding affinities at α7 nAChRs through incorporation of known structural motifs.

Alpha7 nicotinic acetylcholine receptors (nAChRs) have implications in the regulation of cognitive processes such as memory and attention and have been identified as a promising therapeutic target for the treatment of the cognitive deficits associated with schizophrenia and Alzheimer's disease (AD). Structure affinity relationship studies of the previously described α7 agonist SEN12333 (8), have resulted in the identification of compound 45, a potent and selective agonist of the α7 nAChR with enhanced affinity and improved physicochemical properties over the parent compound (SEN12333, 8).

Investigations of amide bond variation and biaryl modification in analogues of α7 nAChR agonist SEN12333.

Several lines of experimental evidence support the involvement of the α7 nAChR in schizophrenia and Alzheimer's disease. Modulators of the α7 nAChR have been extensively reviewed for the treatment of the cognitive deficits associated with these pathologies. SEN12333 represents a novel α7 nAChR agonist chemotype with potential for reduced side effects but requiring further SAR exploration. The present work investigates the amide bond of SEN12333, specifically its connectivity and replacement with the tetrazole functionality, a known cis amide isostere. The results reveal the original amide bond connectivity of SEN12333 to be favorable for binding affinity and agonist activity at α7 nAChRs. The use of a tetrazole isostere completely abolishes affinity and functional activity and suggests that SEN12333 binds in a linear conformation. Results reported herein also suggest the pyridine nitrogen within the terminal aromatic ring of SEN12333 is not essential for binding affinity or functional activity. Further SAR investigations involving manipulation of other moieties contained within SEN12333 are warranted.

"When you're in the hospital, you're in a sort of bubble." Understanding the high risk of self-harm and suicide following psychiatric discharge: a qualitative study.

BACKGROUND: Individuals are at a greatly increased risk of suicide and self-harm in the months following discharge from psychiatric hospital, yet little is known about the reasons for this. AIMS: To investigate the lived experience of psychiatric discharge and explore service users' experiences following discharge. METHOD: In-depth interviews were undertaken with recently discharged service users (n = 10) in the UK to explore attitudes to discharge and experiences since leaving hospital. RESULTS: Informants had mixed attitudes to discharge, and those who had not felt adequately involved in discharge decisions, or disagreed with them, had experienced urges to self-harm since being discharged. Accounts revealed a number of factors that made the postdischarge period difficult; these included both the reemergence of stressors that existed prior to hospitalization and a number of stressors that were prompted or exacerbated by hospitalization. CONCLUSION: Although inferences that can be drawn from the study are limited by the small sample size, the results draw attention to a number of factors that could be investigated further to help explain the high risk of suicide and self-harm following psychiatric discharge. Findings emphasize the importance of adequate preparation for discharge and the maintenance of ongoing relationships with known service providers where possible.

A contact-based intervention for people recently discharged from inpatient psychiatric care: a pilot study.

People recently discharged from inpatient psychiatric care are at high risk of suicide and self-harm, with 6% of all suicides in England occurring in the 3 months after discharge. There is some evidence from a randomized trial carried out in the United States in the 1960s-70s that supportive letters sent by psychiatrists to high-risk patients in the period following hospital discharge resulted in a reduction in suicide. The aim of the current pilot study was to assess the feasibility of conducting a similar trial, but in a broader group of psychiatric discharges, in the context of present day UK clinical practice. The intervention was piloted on 3 psychiatric inpatient wards in southwest England. On 2 wards a series of 8 letters were sent to patients over the 12 months after discharge and 6 letters were sent from the third ward over a 6 month period. A total of 102 patients discharged from the wards received at least 1 letter, but only 45 (44.1%) received the full series of letters. The main reasons for drop-out were patient opt-out (n = 24) or readmission (n = 26). In the context of a policy of intensive follow-up post-discharge, qualitative interviews with service users showed that most already felt adequately supported and the intervention added little to this. Those interviewed felt that it was possible that the intervention might benefit people new to or with little follow-up from mental health services but that fewer letters should be mailed.

A bioassay for the detection of perchlorate in the ppb range.

A bioassay for the determination of ppb (µg·L(-1)) concentrations of perchlorate has been developed and is described herein. The assay uses the enzyme perchlorate reductase (PR) from the perchlorate-reducing organism Dechloromonas agitata in purified and partially purified forms to detect perchlorate. The redox active dye phenazine methosulfate (PMS) is shown to efficiently shuttle electrons to PR from NADH. Perchlorate can be determined indirectly by monitoring NADH oxidization by PR. To lower the detection limit, we have shown that perchlorate can be concentrated on a solid-phase extraction (SPE) column that is pretreated with the cation decyltrimethylammonium bromide (DTAB). Perchlorate is eluted from these columns with a solution of 2 M NaCl and 200 mM morpholine propane sulfonic acid (MOPS, pH 12.5). By washing these columns with 15 mL of 2.5 mM DTAB and 15% acetone, contaminating ions, such as chlorate and nitrate, are removed without affecting the bioassay. Because of the effect of complex matrices on the SPE columns, the method of standard additions is used to analyze tap water and groundwater samples. The efficacy of the developed bioassay was demonstrated by analyzing samples from 2-17000 ppb in deionized lab water, tap water, and contaminated groundwater.

Payer perspectives on pharmacogenomics testing and drug development.

A series of questions about hypothetical drugs and pharmacogenomic tests was posed to a panel of representatives from the health plan, government and employer sectors in order to elicit suggestions for input on data or study design considerations important for coverage determination. The panel suggested seven areas for drug developers to strongly consider. These areas were to include comparative information on new tests versus usual care, assess the negative predictive value of new tests, measure and report on cost offsets, balance relative risk improvement with absolute risk, consider the policy implications of the products or tests, report percentage responders in addition to group mean improvements, and to include specific pharmacogenomic information in US FDA approved labels. The panel was generally enthusiastic about the promise of the field to improve drug selection or dosing.

Hospital admissions for self harm after discharge from psychiatric inpatient care: cohort study.

OBJECTIVE: To determine the risk of non-fatal self harm in the 12 months after discharge from psychiatric inpatient care. DESIGN: Cohort study based on national hospital episode statistics. SETTING: England. Population Patients aged 16-64 years discharged from psychiatric inpatient care between 1 April 2004 and 31 March 2005 and followed up for one year. RESULTS: 75 401 people were discharged from psychiatric inpatient care over the study period, 4935 (6.5%) of whom were admitted at least once for self harm in the following 12 months. Risk of self harm was greatest in the four weeks after discharge; one third (32%, n=1578) of admissions for self harm occurred in this period. The strongest risk factor for self harm after discharge was admission for self harm in the previous 12 months (hazard ratio 4.9, 95% confidence interval 4.6 to 5.2). The risk of self harm was also higher in females, younger people, those with diagnoses of depression, personality disorders, and substance misuse, and those with short lengths of stay. CONCLUSION: More than 6% of patients discharged from psychiatric inpatient care are readmitted for an episode of self harm within 12 months, with one third of these episodes occurring in the month after discharge. Self harm after discharge from hospital shares many of the features of suicide after discharge. Interventions should be developed to reduce risk in this period.

The prediction of self-care behaviors in end-stage renal disease patients using Leventhal's Self-Regulatory Model.

OBJECTIVE: To assess the utility of Leventhal's Self-Regulatory Model (SRM) to predict self-care behavior with regard to dietary, medication, and fluid regimes in end-stage renal disease (ESRD) patients. METHODS: In a prospective study, ESRD patients treated via hospital-based haemodialysis (N=73) were screened for cognitive deficits and completed questionnaires that enquired about illness perceptions, coping strategies, knowledge of kidney disease, and psychological distress at Time 1. Physiological proxy measures of self-care behaviors regarding diet (serum potassium levels), fluid intake (mean and standard deviation of interdialytic weight gain), and medication (serum phosphate levels) regimes were collected 3 weeks later at Time 2. RESULTS: Illness representations (emotional and timeline perceptions) predicted self-care behaviors with regard to diet and medication. Emotion-focused coping strategies predicted higher levels of variation in adherence to fluid restrictions. Younger males were less likely to adhere to the fluid restrictions. CONCLUSIONS: The SRM has predictive utility. Psychological interventions should focus on alleviating disease-specific distress and challenging erroneous timeline perceptions in order to increase adherence to dietary and medication regimes in ESRD patients. A more specific measure of coping for ESRD is required to clarify the role of coping strategies in this population. Younger, male patients should be targeted for extra support with fluid restrictions.

Anaerobic nitrate-dependent iron(II) bio-oxidation by a novel lithoautotrophic betaproteobacterium, strain 2002.

Microbial nitrate-dependent Fe(II) oxidation is known to contribute to iron biogeochemical cycling; however, the microorganisms responsible are virtually unknown. In an effort to elucidate this microbial metabolic process in the context of an environmental system, a 14-cm sediment core was collected from a freshwater lake and geochemically characterized concurrently with the enumeration of the nitrate-dependent Fe(II)-oxidizing microbial community and subsequent isolation of a nitrate-dependent Fe(II)-oxidizing microorganism. Throughout the sediment core, ambient concentrations of Fe(II) and nitrate were observed to coexist. Concomitant most probable number enumeration revealed the presence of an abundant nitrate-dependent Fe(II)-oxidizing microbial community (2.4 x 10(3) to 1.5 x 10(4) cells g(-1) wet sediment) from which a novel anaerobic, lithoautotrophic, Fe(II)-oxidizing bacterium, strain 2002, was isolated. Analysis of the complete 16S rRNA gene sequence revealed that strain 2002 was a member of the beta subclass of the proteobacteria with 94.8% similarity to Chromobacterium violaceum, a bacterium not previously recognized for the ability to oxidize nitrate-dependent Fe(II). Under nongrowth conditions, both strain 2002 and C. violaceum incompletely reduced nitrate to nitrite with Fe(II) as the electron donor, while under growth conditions nitrate was reduced to gaseous end products (N2 and N2O). Lithoautotrophic metabolism under nitrate-dependent Fe(II)-oxidizing conditions was verified by the requirement of CO2 for growth as well as the assimilation of 14C-labeled CO2 into biomass. The isolation of strain 2002 represents the first example of an anaerobic, mesophilic, neutrophilic Fe(II)-oxidizing lithoautotroph isolated from freshwater samples. Our studies further demonstrate the abundance of nitrate-dependent Fe(II) oxidizers in freshwater lake sediments and provide further evidence for the potential of microbially mediated Fe(II) oxidation in anoxic environments.

Anaerobic degradation of benzene, toluene, ethylbenzene, and xylene compounds by Dechloromonas strain RCB.

Dechloromonas strain RCB has been shown to be capable of anaerobic degradation of benzene coupled to nitrate reduction. As a continuation of these studies, the metabolic versatility and hydrocarbon biodegradative capability of this organism were investigated. The results of these revealed that in addition to nitrate, strain RCB could alternatively degrade benzene both aerobically and anaerobically with perchlorate or chlorate [(per)chlorate] as a suitable electron acceptor. Furthermore, with nitrate as the electron acceptor, strain RCB could also utilize toluene, ethylbenzene, and all three isomers of xylene (ortho-, meta-, and para-) as electron donors. While toluene and ethylbenzene were completely mineralized to CO2, strain RCB did not completely mineralize para-xylene but rather transformed it to some as-yet-unidentified metabolite. Interestingly, with nitrate as the electron acceptor, strain RCB degraded benzene and toluene concurrently when the hydrocarbons were added as a mixture and almost 92 microM total hydrocarbons were oxidized within 15 days. The results of these studies emphasize the unique metabolic versatility of this organism, highlighting its potential applicability to bioremediative technologies.