Understanding the evolution of trust in a participatory health research partnership: A qualitative study.

INTRODUCTION: Advancements in evaluating the impact of participatory health research (PHR) have been made through comprehensive models like the community-based participatory research (CBPR) conceptual model, which provides a useful framework for exploring how context and partnership processes can influence health research design and interventions. However, challenges in operationalising aspects of the model limit our understanding and evaluation of the PHR process. Trust is frequently identified as an important component of the CBPR model, which supports the development of key partnership outcomes, such as partnership synergy. However, trust continues to be limited to a binary view (as present or absent), which is problematic given its inherently dynamic and temporal nature. STUDY AIM: The aim of this qualitative study is to understand the evolution of trust in the national public and patient involvement (PPI) network in Ireland. SETTING AND PARTICIPANTS: Participants from the PPI network (n = 15/21) completed a semistructured interview discussing the evolution of trust by reviewing four social network maps derived from a previous longitudinal study. ANALYSIS: Following Braun and Clarke, we used reflexive thematic analysis, to iteratively develop, analyse and interpret our mediated reflection of the data. RESULTS: Participants described the evolution of trust as a function of three contextual factors: (1) the set-up and organisation of the network, (2) how people work together and (3) reflection on the process and outcomes. Their descriptions across these themes seemed to vary depending on partnership type with National Partners and Site Leads having more opportunities to demonstrate trust (e.g., via leadership roles or more resources), compared to Local. Thus, visibility and the opportunity to be visible, depending on the set-up and organisation of the network and how people work together, seemingly play an important role in the evolution of trust over time. Based on these findings, we provide important questions for reflection across themes that could be considered for future PHR partnerships. DISCUSSION: Given that the opportunity and visibility to build and maintain trust over time may not be equally available to all partners, it is important to find ways to invest in and commit to equitable relationships as the key to the success (i.e., longevity) of partnerships. We reflect on/offer important implications for those engaging in PHR partnerships and those who fund such research. PATIENT OR PUBLIC CONTRIBUTION: A Research Advisory Group comprising four research partners (representing academic, service and community organisations) from the PPI Ignite Network provided input and approval for the research objectives of this study as well as previously published work informing this study. Informal consultation occurred with members of this group to discuss findings from this study, assisting with the way findings are presented and described, to be accessible for diverse audiences. Two Research Advisory Group members were involved in the interpretation of the results, and one is a co-author of this manuscript (Zoe Hughes).

Translational Pharmacology of PRAX-944, a Novel T-Type Calcium Channel Blocker in Development for the Treatment of Essential Tremor.

BACKGROUND: Essential tremor is the most common movement disorder with clear unmet need. Mounting evidence indicates tremor is caused by increased neuronal burst firing and oscillations in cerebello-thalamo-cortical circuitry and may be dependent on T-type calcium channel activity. T-type calcium channels regulate sigma band electroencephalogram (EEG) power during non-rapid eye movement sleep, representing a potential biomarker of channel activity. PRAX-944 is a novel T-type calcium channel blocker in development for essential tremor. OBJECTIVES: Using a rat tremor model and sigma-band EEG power, we assessed pharmacodynamically-active doses of PRAX-944 and their translation into clinically tolerated doses in healthy participants, informing dose selection for future efficacy trials. METHODS: Harmaline-induced tremor and spontaneous locomotor activity were used to assess PRAX-944 efficacy and tolerability, respectively, in rats. Sigma-power was used as a translational biomarker of T-type calcium channel blockade in rats and, subsequently, in a phase 1 trial assessing pharmacologic activity and tolerability in healthy participants. RESULTS: In rats, PRAX-944 dose-dependently reduced tremor by 50% and 72% at 1 and 3 mg/kg doses, respectively, without locomotor side effects. These doses also reduced sigma-power by ~30% to 50% in rats. In healthy participants, sigma-power was similarly reduced by 34% to 50% at 10 to 100 mg, with no further reduction at 120 mg. All doses were well tolerated. CONCLUSIONS: In rats, PRAX-944 reduced sigma-power at concentrations that reduced tremor without locomotor side effects. In healthy participants, comparable reductions in sigma-power indicate that robust T-type calcium channel blockade was achieved at well-tolerated doses that may hold promise for reducing tremor in patients with essential tremor. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The novel persistent sodium current inhibitor PRAX-562 has potent anticonvulsant activity with improved protective index relative to standard of care sodium channel blockers.

OBJECTIVE: This study investigates the effects of PRAX-562 on sodium current (INa ), intrinsic neuronal excitability, and protection from evoked seizures to determine whether a preferential persistent INa inhibitor would exhibit improved preclinical efficacy and tolerability compared to two standard voltage-gated sodium channel (NaV ) blockers. METHODS: Inhibition of INa  was characterized using patch clamp analysis. The effect on intrinsic excitability was measured using evoked action potentials recorded from hippocampal CA1 pyramidal neurons in mouse brain slices. Anticonvulsant activity was evaluated using the maximal electroshock seizure (MES) model, and tolerability was assessed by measuring spontaneous locomotor activity (sLMA). RESULTS: PRAX-562 potently and preferentially inhibited persistent INa induced by ATX-II or the SCN8A mutation N1768D (half-maximal inhibitory concentration [IC50 ] = 141 and 75 nmol·L-1 , respectively) relative to peak INa tonic/resting block (60× preference). PRAX-562 also exhibited potent use-dependent block (31× preference to tonic block). This profile is considerably different from standard NaV blockers, including carbamazepine (CBZ; persistent INa IC50 = 77 500 nmol·L-1 , preference ratios of 30× [tonic block], less use-dependent block observed at various frequencies). In contrast to CBZ, PRAX-562 reduced neuronal intrinsic excitability with only a minor reduction in action potential amplitude. PRAX-562 (10 mg/kg po) completely prevented evoked seizures without affecting sLMA (MES unbound brain half-maximal efficacious concentration = 4.3 nmol·L-1 , sLMA half-maximal tolerated concentration = 69.7 nmol·L-1 , protective index [PI] = 16×). In contrast, CBZ and lamotrigine (LTG) had PIs of approximately 5.5×, with significant overlap between doses that were anticonvulsant and that reduced locomotor activity. SIGNIFICANCE: PRAX-562 demonstrated robust preclinical anticonvulsant activity similar to CBZ but improved compared to LTG. PRAX-562 exhibited significantly improved preclinical tolerability compared with standard NaV blockers (CBZ and LTG), potentially due to the preference for persistent INa . Preferential targeting of persistent INa may represent a differentiated therapeutic option for diseases of hyperexcitability, where standard NaV blockers have demonstrated efficacy but poor tolerability.

Helping parents to help children overcome fear: The influence of a short video tutorial.

OBJECTIVES: Anxiety runs in families, and its transmission is largely environmental. However, studies rarely explore this process in clinically anxious parents or ask participants to face a genuine fear. We also do not know whether this process is modifiable. This study will explore these questions using a sample of clinically anxious parents. DESIGN: Experimental design comparing clinically anxious parents with non-anxious parents, and exploring the effects of a tutorial intervention versus a control group. METHODS: Parents with and without anxiety disorders and their children (5-9 years) participated (N = 72). Children chose two fearful animal stimuli. Parents helped the child approach the first in graded steps. The following parental behaviours were recorded: positive/negative verbal information; positive/negative modelling; encouragement/praising of approach/avoidance behaviours. Half the parents were then randomly assigned to a short video tutorial advising how to help children cope with fearful situations. The remainder watched a control video. The approach task was repeated with the second stimulus. RESULTS: Parenting behaviours fell into two categories: 'approach parenting' (encouraging/praising/modelling approach; positive verbal information) and 'avoidance parenting' (encouraging/praising/modelling avoidance; negative verbal information). The parenting tutorial increased 'approach parenting' and decreased 'avoidance parenting' and was associated with increased child approach towards fearful stimuli. This was not moderated by parent or child anxiety. CONCLUSIONS: Parenting, particularly 'avoidance parenting', is associated with children's approach and avoidance. A short video tutorial modified these parenting behaviours and reduced avoidance. These effects were apparent regardless of parent or child anxiety level. PRACTITIONER POINTS: Avoidance and approach parenting may influence children's response to fearful stimuli. Avoidance parenting may be more problematic than lack of approach parenting. Approach and avoidance parenting are amenable to manipulation by short video tutorial. Parenting improvement resulted in increased approach behaviour in children.

Preventing family transmission of anxiety: Feasibility RCT of a brief intervention for parents.

OBJECTIVES: Children of anxious parents are at high risk of anxiety disorders themselves. The evidence suggests that this is due to environmental rather than genetic factors. However, we currently do little to reduce this risk of transmission. There is evidence that supporting parenting in those with mental health difficulties can ameliorate this risk. Therefore, the objective of this study was to test the feasibility of a new one-session, group-based, preventive parenting intervention for parents with anxiety disorders. DESIGN: Feasibility Randomized Controlled Trial. METHODS: A total of 100 parents with anxiety disorders, recruited from adult mental health services in England (and child aged 3-9 years), were randomized to receive the new intervention (a 1-day, group workshop), or to treatment as usual. Children's anxiety disorder and anxiety symptoms were assessed to 12 months by outcome assessors who were blind to group allocation. Exploratory analyses were conducted on an intention to treat basis, as far as possible. RESULTS: A total of 51 participants were randomized to the intervention condition and 49 to the control condition (82% and 80% followed to 12 months, respectively). The attendance rate was 59%, and the intervention was highly acceptable to parents who received it. The RCT was feasible, and 12-month follow-up attrition rates were low. Children whose parents were in the control condition were 16.5% more likely to have an anxiety disorder at follow-up than those in the intervention group. No adverse events were reported. CONCLUSIONS: An inexpensive, light-touch, psycho-educational intervention may be useful in breaking the intergenerational cycle of transmission of anxiety disorders. A substantive trial is warranted. PRACTITIONER POINTS: Anxiety disorders run in families, but we currently do little to help anxious parents to raise confident children. A brief group workshop was highly acceptable to such parents and was very inexpensive to run. Children of parents who took part in the brief intervention were 16.5% less likely to have an anxiety disorder, 1 year later, than children whose parents were in the control group. This was a feasibility study, and while it showed that both the intervention and the research were feasible, the study needs replicating with a much larger sample. Many parents faced barriers to attending the workshop, and future efforts should focus on widening accessibility. We were unable to obtain sufficient self-report data from children, so the outcomes are based on parent report only.

The isozyme selective phosphodiesterase-4 inhibitor, ABI-4, attenuates the effects of lipopolysaccharide in human cells and rodent models of peripheral and CNS inflammation.

Inhibitors of phosphodiesterase-4 (PDE4) have been approved for the treatment of inflammatory disorders, but are associated with dose-limiting nausea and vomiting. These side effects are hypothesized to be mediated by inhibition of the PDE4D isozyme. Here we demonstrate the anti-inflammatory effects of the novel brain penetrant PDE4D-sparing PDE4 inhibitor, ABI-4. ABI-4 was a potent (EC50∼14nM) inhibitor of lipopolysaccharide (LPS) induced TNF-α release from mouse microglia and human PBMCs. ABI-4 (0.32mg/kg) blocked LPS-induced release of pro-inflammatory cytokines (TNF-α, IL-1ß, IL-6) in blood and brain of mice. In a rat model of endotoxin induced uveitis, ABI-4 (0.03-0.3mg/kg) demonstrated steroid-like efficacy in preventing leucocyte infiltration of the aqueous humor when administered 4h after LPS. LPS (0.32mg/kg×5days) caused a 30% upregulation of translocator protein (TSPO) binding which was prevented by co-administration of ABI-4 (0.32mg/kg). In a paradigm to assess motivation, LPS (0.32mg/kg) reduced the number of rewards received, whereas the effect was significantly blunted in mice dosed with ABI-4 (P<0.05) or in PDE4B-/- mice. PDE4B was also shown to modulate brain and plasma levels of TNF-α and IL-1ß in aged mice. Aged mice dosed chronically with ABI-4 (0.32mg/kg) as well as aged PDE4B-/- mice, had significantly lower levels of TNF-α and IL-1ß in brain and plasma relative to vehicle treated or PDE4+/+ mice. Together these data demonstrate that the PDE4D sparing, PDE4 inhibitor, ABI-4 retains potency and efficacy in exerting anti-inflammatory effects. This mechanism warrants further investigation in human disorders involving neuroinflammation.

PDE4B as a microglia target to reduce neuroinflammation.

The importance of microglia in immune homeostasis within the brain is undisputed. Their role in a diversity of neurological and psychiatric diseases as well as CNS injury is the subject of much investigation. Cyclic adenosine monophosphate (AMP) is a critical regulator of microglia homeostasis; as the predominant negative modulator of cyclic AMP signaling within microglia, phosphodiesterase 4 (PDE4) represents a promising target for modulating immune function. PDE4 expression is regulated by inflammation, and in turn, PDE4 inhibition can alter microglia reactivity. As the prototypic PDE4 inhibitor, rolipram, was tested clinically in the 1980s, drug discovery and clinical development of PDE4 inhibitors have been severely hampered by tolerability issues involving nausea and emesis. The two PDE4 inhibitors approved for peripheral inflammatory disorders (roflumilast and apremilast) lack brain penetration and are dose-limited by side effects making them unsuitable for modulating microglial function. Subtype selective inhibitors targeting PDE4B are of high interest given the critical role PDE4B plays in immune function versus the association of PDE4D with nausea and emesis. The challenges and requirements for successful development of a novel brain-penetrant PDE4B inhibitor are discussed in the context of early clinical development strategies. Furthermore, the challenges of monitoring the state of microglia in vivo are highlighted, including a description of the currently available tools and their limitations. Continued drug discovery efforts to identify safe and well-tolerated, brain-penetrant PDE4 inhibitors are a reflection of the confidence in the rationale for modulation of this target to produce meaningful therapeutic benefit in a wide range of neurological conditions and injury. GLIA 2016;64:1698-1709.

Critical data-based re-evaluation of minocycline as a putative specific microglia inhibitor.

Minocycline, a second generation broad-spectrum antibiotic, has been frequently postulated to be a "microglia inhibitor." A considerable number of publications have used minocycline as a tool and concluded, after achieving a pharmacological effect, that the effect must be due to "inhibition" of microglia. It is, however, unclear how this "inhibition" is achieved at the molecular and cellular levels. Here, we weigh the evidence whether minocycline is indeed a bona fide microglia inhibitor and discuss how data generated with minocycline should be interpreted. GLIA 2016;64:1788-1794.

Substance misuse: can midwives really make a difference?

Substance misuse makes a woman vulnerable. During pregnancy, in particular, the issues surrounding Substance misuse and its treatment are very emotive. Pregnancy often prompts women who substance misuse to seek help for their addiction for the first time, but for some it is part of a cycle of failure and loss: failure at rehabilitation and facing the loss of yet another child, be it through child protection issues or from the medical complications of addiction. As a midwife only engages with a woman for a relatively short period of time, can their actions have a lifelong impact on the woman and her unborn child? This article aims to examine the stigma of substance misuse and the role a midwife plays, not just as a maternity care provider but also in the continued journey of the woman and her child.

Amphetamine decreases α2C-adrenoceptor binding of [11C]ORM-13070: a PET study in the primate brain.

BACKGROUND: The neurotransmitter norepinephrine has been implicated in psychiatric and neurodegenerative disorders. Examination of synaptic norepinephrine concentrations in the living brain may be possible with positron emission tomography (PET), but has been hampered by the lack of suitable radioligands. METHODS: We explored the use of the novel α2C-adrenoceptor antagonist PET tracer [(11)C]ORM-13070 for measurement of amphetamine-induced changes in synaptic norepinephrine. The effect of amphetamine on [(11)C]ORM-13070 binding was evaluated ex vivo in rat brain sections and in vivo with PET imaging in monkeys. RESULTS: Microdialysis experiments confirmed amphetamine-induced elevations in rat striatal norepinephrine and dopamine concentrations. Regional [(11)C]ORM-13070 receptor binding was high in the striatum and low in the cerebellum. After injection of [(11)C]ORM-13070 in rats, mean striatal specific binding ratios, determined using cerebellum as a reference region, were 1.4±0.3 after vehicle pretreatment and 1.2±0.2 after amphetamine administration (0.3mg/kg, subcutaneous). Injection of [(11)C]ORM-13070 in non-human primates resulted in mean striatal binding potential (BP ND) estimates of 0.65±0.12 at baseline. Intravenous administration of amphetamine (0.5 and 1.0mg/kg, i.v.) reduced BP ND values by 31-50%. Amphetamine (0.3mg/kg, subcutaneous) increased extracellular norepinephrine (by 400%) and dopamine (by 270%) in rat striata. CONCLUSIONS: Together, these results indicate that [(11)C]ORM-13070 may be a useful tool for evaluation of synaptic norepinephrine concentrations in vivo. Future studies are required to further understand a potential contribution of dopamine to the amphetamine-induced effect.

GM-1020: a novel, orally bioavailable NMDA receptor antagonist with rapid and robust antidepressant-like effects at well-tolerated doses in rodents.

The NMDA receptor (NMDAR) antagonist ketamine has shown great potential as a rapid-acting antidepressant; however, its use is limited by poor oral bioavailability and a side effect profile that necessitates in-clinic dosing. GM-1020 is a novel NMDAR antagonist that was developed to address these limitations of ketamine as a treatment for depression. Here, we present the preclinical characterization of GM-1020 alongside ketamine, for comparison. In vitro, we profiled GM-1020 for binding to NMDAR and functional inhibition using patch-clamp electrophysiology. In vivo, GM-1020 was assessed for antidepressant-like efficacy using the Forced Swim Test (FST) and Chronic Mild Stress (CMS), while motor side effects were assessed in spontaneous locomotor activity and on the rotarod. The pharmacokinetic properties of GM-1020 were profiled across multiple preclinical species. Electroencephalography (EEG) was performed to determine indirect target engagement and provide a potentially translational biomarker. These results demonstrate that GM-1020 is an orally bioavailable NMDAR antagonist with antidepressant-like efficacy at exposures that do not produce unwanted motor effects.

Hurricane-induced failure of low salinity wetlands.

During the 2005 hurricane season, the storm surge and wave field associated with Hurricanes Katrina and Rita eroded 527 km(2) of wetlands within the Louisiana coastal plain. Low salinity wetlands were preferentially eroded, while higher salinity wetlands remained robust and largely unchanged. Here we highlight geotechnical differences between the soil profiles of high and low salinity regimes, which are controlled by vegetation and result in differential erosion. In low salinity wetlands, a weak zone (shear strength 500-1450 Pa) was observed approximately 30 cm below the marsh surface, coinciding with the base of rooting. High salinity wetlands had no such zone (shear strengths > 4500 Pa) and contained deeper rooting. Storm waves during Hurricane Katrina produced shear stresses between 425-3600 Pa, sufficient to cause widespread erosion of the low salinity wetlands. Vegetation in low salinity marshes is subject to shallower rooting and is susceptible to erosion during large magnitude storms; these conditions may be exacerbated by low inorganic sediment content and high nutrient inputs. The dramatic difference in resiliency of fresh versus more saline marshes suggests that the introduction of freshwater to marshes as part of restoration efforts may therefore weaken existing wetlands rendering them vulnerable to hurricanes.

A meta-analytical review of the impact of mindfulness on creativity: Framing current lines of research and defining moderator variables.

Findings relating to the impact of mindfulness interventions on creative performance remain inconsistent, perhaps because of discrepancies between study designs, including variability in the length of mindfulness interventions, the absence of control groups or the tendencies to explore creativity as one unitary construct. To derive a clearer understanding of the impact that mindfulness interventions may exert on creative performance, two meta-analytical reviews were conducted, drawing respectively on studies using a control group design (n = 20) and studies using a pretest-posttest design (n = 17). A positive effect was identified between mindfulness and creativity, both for control group designs (d = 0.42, 95% CIs [0.29, 0.54]) and pretest-posttest designs (d = 0.59, 95% CIs [0.38, 0.81]). Subgroup analysis revealed that intervention length, creativity task (i.e., divergent vs. convergent thinking tasks) and control group type, were significant moderators for control group studies, whereas only intervention length was a significant moderator for pretest-posttest studies. Overall, the findings support the use of mindfulness as a tool to enhance creative performance, with more advantageous outcomes for convergent as opposed to divergent thinking tasks. We discuss the implications of study design and intervention length as key factors of relevance to future research aimed at advancing theoretical accounts of the relationship between mindfulness and creativity.

Long-term sea level rise modeling of a basin-tidal inlet system reveals sediment sinks.

Much of the world's population lives close to coastlines and this proximity is becoming increasingly impactful because of sea-level rise (SLR). Barrier islands and backbarrier saltmarshes, which comprise >10% of these coasts, are particularly susceptible. To better understand this risk, we model backbarrier morphologic and hydrodynamic evolution over a 200-year period of SLR, incorporating an erodible bed and a range of grain sizes. Here, we show that reduction in intertidal area creates negative feedback, shifting transport of coarse sediment (silt and sand) through the inlet from net export to net import. Imposing a modest marsh vertical accretion rate decreases the period of silt and sand import to 40 years (years 90 to 130) before being exported again. Clay is continuously exported thereby decreasing inorganic deposition on marshes and threatening their sustainability. Simulated marsh loss increases tidal prism and the volume of sand contained in ebb deltas, depleting coastal sand resources.

With equity in mind: Evaluating an interactive hybrid global surgery course for cross-site interdisciplinary learners.

There is limited understanding of the role of transcultural, cross-site educational partnerships for global surgery training between high- and low- or middle-income country (LMIC) institutions. We describe the development, delivery, and appraisal of a hybrid, synchronous, semester-long Global Surgical Care course by global health collaborators from widely different contexts, and evaluate the equity of the collaboration. The course was collaboratively modified by surgical educators and public health professionals with emphasis on collaboration ethics. Faculty from high-income and LMICs were paired to deliver lectures. To collaborate internationally, students and faculty participated either onsite or online. Perceptions and knowledge gained were quantitatively evaluated through participant and faculty cross-sectional surveys, using Likert scales, prioritization rankings, and free text responses analysed qualitatively. Equity was assessed using the Fair Trade Learning rubric and additional probes. Thirty-five learners from six institutions participated. Teams produced mock National, Surgical, Obstetric, and Anaesthesia Plans (NSOAPs) for selected LMICs, and reported a 9% to 65% increase in self-reported global health competencies following the course. Online learners had favourable perceptions of learning, but experienced connectivity challenges. Barriers to effective group work included time differences and logistics of communication for dispersed team members. Individuals taking the course for academic credit scored significantly higher than other learners in peer assessments of participation (8.56±1.53 versus 5.03±3.14; p<0.001). Using the Fair Trade Rubric, 60% of equity indicators were ideal, and no respondents perceived neo-colonialism in the partnership. Blended, synchronous, interdisciplinary global surgery courses based on "North-South" partnerships with a focus on equity in design and delivery are feasible but require careful and deliberate planning to minimize epistemic injustice. Such programs should address surgical systems strengthening, and not create dependency. Equity in such engagements should be evaluated and monitored in an ongoing fashion to stimulate discussion and continuous improvement.

Cannabis psychosis: examining the evidence for a distinctive psychopathology in a systematic and narrative review.

BACKGROUND: The term "cannabis psychosis" has become ubiquitous in the psychiatric literature. Few authors have described the precise psychopathology of this potentially distinct subtype of psychosis. Specifically, little attention has been paid to exploring whether cannabis psychosis is characterized by a psychopathology which is different from that of other types of psychosis. OBJECTIVE: The purpose of this paper was to systematically review the literature for evidence of a specific constellation of symptoms which are consistently characteristic of cannabis psychosis within an inpatient psychiatric setting and to determine whether these combine to create a psychopathology which is distinct from that of other types of psychosis. METHOD: Systematic review using Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. RESULTS: 13 studies of the 439 identified met the inclusion criteria. Only eight studies had sufficient internal and external validity to allow comparison in a narrative format of the psychopathology present, compared with controls. Of these eight selected studies, seven reported at least one significant difference (p < .05) in the psychopathology of the cannabis group to the control group used as a comparator. DISCUSSION AND CONCLUSION: This study should be interpreted with great caution and conclusions should not be generalized. These findings do not suggest that "cannabis psychosis" does not exist, only that from a psychopathological perspective it may not be qualitatively any different from other forms of psychosis. Future research in this area needs to focus on clarifying the definition or description of "cannabis psychosis" and the use of standardized robust experimental and/or observational designs to eliminate heterogeneity that may lead to inconclusive results.

The public and patient involvement imperative in Ireland: Building on policy drivers.

What can we learn from the history of Public and Patient Involvement (PPI) in healthcare and research across global jurisdictions? Depending on region and context, the terminology and heritage of involvement in research vary. In this paper, we draw on global traditions to explore dominant themes and key considerations and critiques pertaining to PPI in order to inform a PPI culture shift in Ireland. We then describe the heritage of PPI in Ireland and present the case for combining methodological imperatives with policy drivers to support and encourage meaningful involvement. Specifically, we propose that PPI can be enriched by the theory and processes of participatory health research (PHR); and that implementation requires concurrent capacity building. We conclude with a call for Irish researchers (authors of this paper included) to consider the conceptual complexities and nuances of a participatory approach to build on the policy imperatives driving PPI and to contribute to the international evidence base and research culture. Specifically, we call for Irish health researchers and funders to consider and reflect on: (1) the rich literature of PHR as a resource for enacting meaningful PPI; (2) the roots and origins of varying participatory health research methods; (3) how community/patient groups can lead health research; and (4) co-learning and partnership synergy to create space for both academic and community expertise; and (5) the importance of using standardized reporting tools.

First-in-Human Evaluation of 18F-PF-06445974, a PET Radioligand That Preferentially Labels Phosphodiesterase-4B.

Phosphodiesterase-4 (PDE4), which metabolizes the second messenger cyclic adenosine monophosphate (cAMP), has 4 isozymes: PDE4A, PDE4B, PDE4C, and PDE4D. PDE4B and PDE4D have the highest expression in the brain and may play a role in the pathophysiology and treatment of depression and dementia. This study evaluated the properties of the newly developed PDE4B-selective radioligand 18F-PF-06445974 in the brains of rodents, monkeys, and humans. Methods: Three monkeys and 5 healthy human volunteers underwent PET scans after intravenous injection of 18F-PF-06445974. Brain uptake was quantified as total distribution volume (V T) using the standard 2-tissue-compartment model and serial concentrations of parent radioligand in arterial plasma. Results: 18F-PF-06445974 readily distributed throughout monkey and human brain and had the highest binding in the thalamus. The value of V T was well identified by a 2-tissue-compartment model but increased by 10% during the terminal portions (40 and 60 min) of the monkey and human scans, respectively, consistent with radiometabolite accumulation in the brain. The average human V T values for the whole brain were 9.5 ± 2.4 mL ⋅ cm-3 Radiochromatographic analyses in knockout mice showed that 2 efflux transporters-permeability glycoprotein (P-gp) and breast cancer resistance protein (BCRP)-completely cleared the problematic radiometabolite but also partially cleared the parent radioligand from the brain. In vitro studies with the human transporters suggest that the parent radioligand was a partial substrate for BCRP and, to a lesser extent, for P-gp. Conclusion: 18F-PF-06445974 quantified PDE4B in the human brain with reasonable, but not complete, success. The gold standard compartmental method of analyzing brain and plasma data successfully identified the regional densities of PDE4B, which were widespread and highest in the thalamus, as expected. Because the radiometabolite-induced error was only about 10%, the radioligand is, in the opinion of the authors, suitable to extend to clinical studies.

The metabotropic glutamate receptor 7 allosteric modulator AMN082: a monoaminergic agent in disguise?

Metabotropic glutamate receptor 7 (mGluR7) remains the most elusive of the eight known mGluRs primarily because of the limited availability of tool compounds to interrogate its potential therapeutic utility. The discovery of N,N'-dibenzhydrylethane-1,2-diamine dihydrochloride (AMN082) as the first orally active, brain-penetrable, mGluR7-selective allosteric agonist by Mitsukawa and colleagues (Proc Natl Acad Sci USA 102:18712-18717, 2005) provides a means to investigate this receptor system directly. AMN082 demonstrates mGluR7 agonist activity in vitro and interestingly has a behavioral profile that supports utility across a broad spectrum of psychiatric disorders including anxiety and depression. The present studies were conducted to extend the in vitro and in vivo characterization of AMN082 by evaluating its pharmacokinetic and metabolite profile. Profiling of AMN082 in rat liver microsomes revealed rapid metabolism (t(1/2) < 1 min) to a major metabolite, N-benzhydrylethane-1,2-diamine (Met-1). In vitro selectivity profiling of Met-1 demonstrated physiologically relevant transporter binding affinity at serotonin transporter (SERT), dopamine transporter (DAT), and norepinephrine transporter (NET) (323, 3020, and 3410 nM, respectively); whereas the parent compound AMN082 had appreciable affinity at NET (1385 nM). AMN082 produced antidepressant-like activity and receptor occupancy at SERT up to 4 h postdose, a time point at which AMN082 is significantly reduced in brain and plasma while the concentration of Met-1 continues to increase in brain. Acute Met-1 administration produced antidepressant-like activity as would be expected from its in vitro profile as a mixed SERT, NET, DAT inhibitor. Taken together, these data suggest that the reported in vivo actions of AMN082 should be interpreted with caution, because they may involve other mechanisms in addition to mGluR7.