High-yield methods for accurate two-alternative visual psychophysics in head-fixed mice

Research in neuroscience increasingly relies on the mouse, a mammalian species that affords unparalleled genetic tractability and brain atlases. Here, we introduce high-yield methods for probing mouse visual decisions. Mice are head-fixed, facilitating repeatable visual stimulation, eye tracking, and brain access. They turn a steering wheel to make two alternative choices, forced or unforced. Learning is rapid thanks to intuitive coupling of stimuli to wheel position. The mouse decisions deliver high-quality psychometric curves for detection and discrimination and conform to the predictions of a simple probabilistic observer model. The task is readily paired with two-photon imaging of cortical activity. Optogenetic inactivation reveals that the task requires mice to use their visual cortex. Mice are motivated to perform the task by fluid reward or optogenetic stimulation of dopamine neurons. This stimulation elicits a larger number of trials and faster learning. These methods provide a platform to accurately probe mouse vision and its neural basis

Lamotrigine for people with borderline personality disorder: a RCT

Background: No drug treatments are currently licensed for the treatment of borderline personality disorder (BPD). Despite this, people with this condition are frequently prescribed psychotropic medications and often with considerable polypharmacy. Preliminary studies have indicated that mood stabilisers may be of benefit to people with BPD. Objective: To examine the clinical effectiveness and cost-effectiveness of lamotrigine for people with BPD. Design: A two-arm, double-blind, placebo-controlled individually randomised trial of lamotrigine versus placebo. Participants were randomised via an independent and remote web-based service using permuted blocks and stratified by study centre, the severity of personality disorder and the extent of hypomanic symptoms. Setting: Secondary care NHS mental health services in six centres in England. Participants: Potential participants had to be aged ≥ 18 years, meet diagnostic criteria for BPD and provide written informed consent. We excluded people with coexisting psychosis or bipolar affective disorder, those already taking a mood stabiliser, those who spoke insufficient English to complete the baseline assessment and women who were pregnant or contemplating becoming pregnant. Interventions: Up to 200 mg of lamotrigine per day or an inert placebo. Women taking combined oral contraceptives were prescribed up to 400 mg of trial medication per day. Main outcome measures: Outcomes were assessed at 12, 24 and 52 weeks after randomisation. The primary outcome was the total score on the Zanarini Rating Scale for Borderline Personality Disorder (ZAN-BPD) at 52 weeks. The secondary outcomes were depressive symptoms, deliberate self-harm, social functioning, health-related quality of life, resource use and costs, side effects of treatment and adverse events. Higher scores on all measures indicate poorer outcomes. Results: Between July 2013 and October 2015 we randomised 276 participants, of whom 195 (70.6%) were followed up 52 weeks later. At 52 weeks, 49 (36%) of those participants prescribed lamotrigine and 58 (42%) of those prescribed placebo were taking it. At 52 weeks, the mean total ZAN-BPD score was 11.3 [standard deviation (SD) 6.6] among those participants randomised to lamotrigine and 11.5 (SD 7.7) among those participants randomised to placebo (adjusted mean difference 0.1, 95% CI –1.8 to 2.0; p = 0.91). No statistically significant differences in secondary outcomes were seen at any time. Adjusted costs of direct care for those prescribed lamotrigine were similar to those prescribed placebo. Limitations: Levels of adherence in this pragmatic trial were low, but greater adherence was not associated with better mental health. Conclusions: The addition of lamotrigine to the usual care of people with BPD was not found to be clinically effective or provide a cost-effective use of resources. Future work: Future research into the treatment of BPD should focus on improving the evidence base for the clinical effectiveness and cost-effectiveness of non-pharmacological treatments to help policy-makers make better decisions about investing in specialist treatment services

Individual common variants exert weak effects on the risk for autism spectrum disorders.

While it is apparent that rare variation can play an important role in the genetic architecture of autism spectrum disorders (ASDs), the contribution of common variation to the risk of developing ASD is less clear. To produce a more comprehensive picture, we report Stage 2 of the Autism Genome Project genome-wide association study, adding 1301 ASD families and bringing the total to 2705 families analysed (Stages 1 and 2). In addition to evaluating the association of individual single nucleotide polymorphisms (SNPs), we also sought evidence that common variants, en masse, might affect the risk. Despite genotyping over a million SNPs covering the genome, no single SNP shows significant association with ASD or selected phenotypes at a genome-wide level. The SNP that achieves the smallest P-value from secondary analyses is rs1718101. It falls in CNTNAP2, a gene previously implicated in susceptibility for ASD. This SNP also shows modest association with age of word/phrase acquisition in ASD subjects, of interest because features of language development are also associated with other variation in CNTNAP2. In contrast, allele scores derived from the transmission of common alleles to Stage 1 cases significantly predict case status in the independent Stage 2 sample. Despite being significant, the variance explained by these allele scores was small (Vm< 1%). Based on results from individual SNPs and their en masse effect on risk, as inferred from the allele score results, it is reasonable to conclude that common variants affect the risk for ASD but their individual effects are modest

[18F]Difluorocarbene for Positron Emission Tomography

The advent of total-body Positron Emission Tomography (PET) has vastly broadened the range of research and clinical applications of this powerful molecular imaging technology1. Such possibilities have accelerated progress in 18F-radiochemistry with numerous methods available to 18F-label (hetero)arenes and alkanes2. However, access to 18F-difluoromethylated molecules in high molar activity (Am) is largely an unsolved problem, despite the indispensability of the difluoromethyl group for pharmaceutical drug discovery3. We report herein a general solution by introducing carbene chemistry to the field of nuclear imaging with a [18F]difluorocarbene reagent capable of a myriad of 18F-difluoromethylation processes. In contrast to the tens of known difluorocarbene reagents, this 18F-reagent is carefully designed for facile accessibility, high molar activity and versatility. The issue of Am is solved using an assay examining the likelihood of isotopic dilution upon variation of the electronics of the difluorocarbene precursor. Versatility is demonstrated with multiple [18F]difluorocarbene based reactions including O–H, S–H and N–H insertions, and cross-couplings that harness the reactivity of ubiquitous functional groups such as (thio)phenols, N-heteroarenes, and aryl boronic acids that are easy to install. Impact is illustrated with the labelling of highly complex and functionalised biologically relevant molecules and radiotracers

Switching antipsychotic medication to reduce sexual dysfunction in people with psychosis: the REMEDY RCT

BackgroundSexual dysfunction is common among people who are prescribed antipsychotic medication for psychosis. Sexual dysfunction can impair quality of life and reduce treatment adherence. Switching antipsychotic medication may help, but the clinical effectiveness and cost-effectiveness of this approach is unclear.ObjectiveTo examine whether or not switching antipsychotic medication provides a clinically effective and cost-effective method to reduce sexual dysfunction in people with psychosis.DesignA two-arm, researcher-blind, pilot randomised trial with a parallel qualitative study and an internal pilot phase. Study participants were randomised to enhanced standard care plus a switch of antipsychotic medication or enhanced standard care alone in a 1?:?1 ratio. Randomisation was via an independent and remote web-based service using dynamic adaptive allocation, stratified by age, gender, Trust and relationship status.SettingNHS secondary care mental health services in England.ParticipantsPotential participants had to be aged ??18 years, have schizophrenia or related psychoses and experience sexual dysfunction associated with the use of antipsychotic medication. We recruited only people for whom reduction in medication dosage was ineffective or inappropriate. We excluded those who were acutely unwell, had had a change in antipsychotic medication in the last 6 weeks, were currently prescribed clozapine or whose sexual dysfunction was believed to be due to a coexisting physical or mental disorder.InterventionsSwitching to an equivalent dose of one of three antipsychotic medications that are considered to have a relatively low propensity for sexual side effects (i.e. quetiapine, aripiprazole or olanzapine). All participants were offered brief psychoeducation and support to discuss their sexual health and functioning.Main outcome measuresThe primary outcome was patient-reported sexual dysfunction, measured using the Arizona Sexual Experience Scale. Secondary outcomes were researcher-rated sexual functioning, mental health, side effects of medication, health-related quality of life and service utilisation. Outcomes were assessed 3 and 6 months after randomisation. Qualitative data were collected from a purposive sample of patients and clinicians to explore barriers to recruitment.Sample sizeAllowing for a 20% loss to follow-up, we needed to recruit 216 participants to have 90% power to detect a 3-point difference in total Arizona Sexual Experience Scale score (standard deviation 6.0 points) using a 0.05 significance level.ResultsThe internal pilot was discontinued after 12 months because of low recruitment. Ninety-eight patients were referred to the study between 1 July 2018 and 30 June 2019, of whom 10 were randomised. Eight (80%) participants were followed up 3 months later. Barriers to referral and recruitment included staff apprehensions about discussing side effects, reluctance among patients to switch medication and reticence of both staff and patients to talk about sex.LimitationsInsufficient numbers of participants were recruited to examine the study hypotheses.ConclusionsIt may not be possible to conduct a successful randomised trial of switching antipsychotic medication for sexual functioning in people with psychosis in the NHS at this time.Future workResearch examining the acceptability and effectiveness of adjuvant phosphodiesterase inhibitors should be considered.Trial registrationCurrent Controlled Trials ISRCTN12307891.FundingThis project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 44. See the NIHR Journals Library website for further project information

Strong mitochondrial DNA support for a Cretaceous origin of modern avian lineages

<p>Abstract</p> <p>Background</p> <p>Determining an absolute timescale for avian evolutionary history has proven contentious. The two sources of information available, paleontological data and inference from extant molecular genetic sequences (colloquially, 'rocks' and 'clocks'), have appeared irreconcilable; the fossil record supports a Cenozoic origin for most modern lineages, whereas molecular genetic estimates suggest that these same lineages originated deep within the Cretaceous and survived the K-Pg (Cretaceous-Paleogene; formerly Cretaceous-Tertiary or K-T) mass-extinction event. These two sources of data therefore appear to support fundamentally different models of avian evolution. The paradox has been speculated to reflect deficiencies in the fossil record, unrecognized biases in the treatment of genetic data or both. Here we attempt to explore uncertainty and limit bias entering into molecular divergence time estimates through: (i) improved taxon (<it>n </it>= 135) and character (<it>n = </it>4594 bp mtDNA) sampling; (ii) inclusion of multiple cladistically tested internal fossil calibration points (<it>n </it>= 18); (iii) correction for lineage-specific rate heterogeneity using a variety of methods (<it>n </it>= 5); (iv) accommodation of uncertainty in tree topology; and (v) testing for possible effects of episodic evolution.</p> <p>Results</p> <p>The various 'relaxed clock' methods all indicate that the major (basal) lineages of modern birds originated deep within the Cretaceous, although temporal intraordinal diversification patterns differ across methods. We find that topological uncertainty had a systematic but minor influence on date estimates for the origins of major clades, and Bayesian analyses assuming fixed topologies deliver similar results to analyses with unconstrained topologies. We also find that, contrary to expectation, rates of substitution are not autocorrelated across the tree in an ancestor-descendent fashion. Finally, we find no signature of episodic molecular evolution related to either speciation events or the K-Pg boundary that could systematically mislead inferences from genetic data.</p> <p>Conclusion</p> <p>The 'rock-clock' gap has been interpreted by some to be a result of the vagaries of molecular genetic divergence time estimates. However, despite measures to explore different forms of uncertainty in several key parameters, we fail to reconcile molecular genetic divergence time estimates with dates taken from the fossil record; instead, we find strong support for an ancient origin of modern bird lineages, with many extant orders and families arising in the mid-Cretaceous, consistent with previous molecular estimates. Although there is ample room for improvement on both sides of the 'rock-clock' divide (e.g. accounting for 'ghost' lineages in the fossil record and developing more realistic models of rate evolution for molecular genetic sequences), the consistent and conspicuous disagreement between these two sources of data more likely reflects a genuine difference between estimated ages of (i) stem-group origins and (ii) crown-group morphological diversifications, respectively. Further progress on this problem will benefit from greater communication between paleontologists and molecular phylogeneticists in accounting for error in avian lineage age estimates.</p

Quantifying HIV transmission flow between high-prevalence hotspots and surrounding communities: a population-based study in Rakai, Uganda

Background International and global organisations advocate targeting interventions to areas of high HIV prevalence (ie, hotspots). To better understand the potential benefits of geo-targeted control, we assessed the extent to which HIV hotspots along Lake Victoria sustain transmission in neighbouring populations in south-central Uganda. Methods We did a population-based survey in Rakai, Uganda, using data from the Rakai Community Cohort Study. The study surveyed all individuals aged 15–49 years in four high-prevalence Lake Victoria fishing communities and 36 neighbouring inland communities. Viral RNA was deep sequenced from participants infected with HIV who were antiretroviral therapy-naive during the observation period. Phylogenetic analysis was used to infer partial HIV transmission networks, including direction of transmission. Reconstructed networks were interpreted through data for current residence and migration history. HIV transmission flows within and between high-prevalence and low-prevalence areas were quantified adjusting for incomplete sampling of the population. Findings Between Aug 10, 2011, and Jan 30, 2015, data were collected for the Rakai Community Cohort Study. 25 882 individuals participated, including an estimated 75·7% of the lakeside population and 16·2% of the inland population in the Rakai region of Uganda. 5142 participants were HIV-positive (2703 [13·7%] in inland and 2439 [40·1%] in fishing communities). 3878 (75·4%) people who were HIV-positive did not report antiretroviral therapy use, of whom 2652 (68·4%) had virus deep-sequenced at sufficient quality for phylogenetic analysis. 446 transmission networks were reconstructed, including 293 linked pairs with inferred direction of transmission. Adjusting for incomplete sampling, an estimated 5·7% (95% credibility interval 4·4–7·3) of transmissions occurred within lakeside areas, 89·2% (86·0–91·8) within inland areas, 1·3% (0·6–2·6) from lakeside to inland areas, and 3·7% (2·3–5·8) from inland to lakeside areas. Interpretation Cross-community HIV transmissions between Lake Victoria hotspots and surrounding inland populations are infrequent and when they occur, virus more commonly flows into rather than out of hotspots. This result suggests that targeted interventions to these hotspots will not alone control the epidemic in inland populations, where most transmissions occur. Thus, geographical targeting of high prevalence areas might not be effective for broader epidemic control depending on underlying epidemic dynamics. Funding The Bill & Melinda Gates Foundation, the National Institute of Allergy and Infectious Diseases, the National Institute of Mental Health, the National Institute of Child Health and Development, the Division of Intramural Research of the National Institute for Allergy and Infectious Diseases, the World Bank, the Doris Duke Charitable Foundation, the Johns Hopkins University Center for AIDS Research, and the President's Emergency Plan for AIDS Relief through the Centers for Disease Control and Prevention

The clinical effectiveness and cost effectiveness of lamotrigine for people with borderline personality disorder: a randomized, placebo-controlled trial

Objectives: To examine whether lamotrigine is a clinically effective and cost-effective treatment for people with borderline personality disorder. Method: Multicentre, double-blind, placebo-controlled randomized trial. Between July 2013 to November 2016, we recruited 276 people aged 18 or over, who met diagnostic criteria for borderline personality disorder. We excluded those with co-existing bipolar affective disorder or psychosis, those already taking a mood stabiliser, and women at risk of pregnancy. We randomly allocated participants on a 1:1 ratio to up to 400mg of lamotrigine per day or an inert placebo using a remote web-based randomization service. The primary outcome was total score on the Zanarini Rating scale for Borderline Personality Disorder (ZAN-BPD) at 52 weeks. Secondary outcomes included depressive symptoms, deliberate self-harm, social functioning, health-related quality of life, resource use and costs, side effects of treatment and adverse events. Results: 195 (70.6%) participants were followed up at 52 weeks, at which point 49 (36%) of those prescribed lamotrigine and 58 (42%) of those prescribed placebo were taking it. Mean total ZAN-BPD score was 11.3 (SD = 6.6) among those randomized to lamotrigine and 11.5 (SD = 7.7) among those randomized to placebo (adjusted difference in means = 0.1, 95% C.I = -1.8 to 2.0, p=0.91). There was no evidence of any differences in secondary outcomes. Costs of direct care for those prescribed lamotrigine were similar to those prescribed placebo. Conclusions: Treating people with borderline personality disorder with lamotrigine is not a clinically effective or cost-effective use of resources