G-protein-coupled receptors for free fatty acids: nutritional and therapeutic targets

It is becoming evident that nutrients and metabolic intermediates derived from such nutrients regulate cellular function by activating a number of cell-surface G-protein coupled receptors (GPCRs). Until now, members of the GPCR family have largely been considered as the molecular targets that communicate cellular signals initiated by hormones and neurotransmitters. Recently, based on tissue expression patterns of these receptors and the concept that they may elicit the production of a range of appetite- and hunger-regulating peptides, such nutrient sensing GPCRs are attracting considerable attention due to their potential to modulate satiety, improve glucose homeostasis and supress the production of various pro-inflammatory mediators. Despite the developing interests in these nutrients sensing GPCR both as sensors of nutritional status, and targets for limiting the development of metabolic diseases, major challenges remain to exploit their potential for therapeutic purposes. Mostly, this is due to limited characterisation and validation of these receptors because of paucity of selective and high-potency/affinity pharmacological agents to define the detailed function and regulation of these receptors. However, ongoing clinical trials of agonists of free fatty acid receptor 1 suggest that this receptor and other receptors for free fatty acids may provide a successful strategy for controlling hyperglycaemia and providing novel approaches to treat diabetes. Receptors responsive to free fatty acid have been of particular interest, and some aspects of these are considered herein

The use of receptor chimeras to study the function of the carboxyl terminal domain in prostacyclin receptor signalling

To investigate the role of the carboxyl terminal in the regulation of the prostacyclin (IP) receptor, chimeric receptors expressing the carboxyl termini of either the thyrotropin-releasing hormone-1 (TRH) receptor or the beta2-adrenoreceptor (beta2-AR) were generated. Furthermore, C-terminally green fluorescent protein (GFP)-tagged forms of the receptors were built and stably expressed in HEK293 cells, thus enabling direct visualisation of receptor localisation and trafficking in intact cells. Pharmacological analysis of the receptor-GFP fusion proteins demonstrated that each bound [3H] iloprost with similar affinity and coupled to increased cAMP production. Sequestration studies revealed that iloprost-induced internalisation of the prostacyclin receptor was augmented by the addition of the TRH carboxyl tail. Conversely, the P2-tailed chimeras exhibited internalisation properties comparable to those of the full- length prostacyclin receptors. The receptors' internalisation kinetics were unaffected by the addition of the GFP moiety. Agonist-mediated sequestration of the constructs was abolished by treatments inducing clathrin depletion. In addition, sequestered receptors were found to colocalise in endosomes containing transferrin, as determined by confocal microscopy. Visual assessment of the dynamic interaction between P-arrestins and the receptor proteins demonstrated that sequestration of the full-length receptor proceeded primarily via an arrestin-independent mechanism. Switching of the receptor's carboxyl domain for the equivalent beta2-AR sequence did not confer beta-arrestin sensitivity to the receptor. In contrast, the TRH-tailed receptors exhibited an increased binding affinity for beta-arrestins, internalising in complexes with beta-arrestin 2. In a cellular milieu deficient of P- airestins and GRKs, the prostacyclin receptor and its chimeric forms retained the ability to undergo agonist-mediated sequestration. Analysis of receptor regulation revealed that the GFP-tagged IP receptor elicited rapid signal attenuation in response to iloprost challenge. A less striking desensitisation response was evident with receptors expressing the different carboxyl tails. During desensitisation of the receptor-GFP proteins, iloprost challenge induced rapid receptor phosphorylation which was, in part, mediated by the second messenger kinases PICA and PKC. PKA was demonstrated to be a major desensitising kinase of the receptors while PKC phosphorylation was identified as a possible determinant for receptor sequestration. Upon agonist withdrawal, the internalised GFP-tagged full-length receptor recycled rapidly back to the plasmalemmal surface, which was followed by the restoration in receptor responsiveness. By comparison, the agonist-activated chimeric receptors failed to recycle, and therefore resensitise, after agonist removal. Subsequently, the intracellularly retained chimeric receptors were sorted predominantly via a degradative pathway. Taken together, these data highlight the importance of the carboxyl terminal domain in prostacyclin receptor function

A qualitative exploration of the relevance of training provision in planning for implementation of managed alcohol programs within a third sector setting

Background: Managed Alcohol Programs (MAPs) are a harm reduction strategy for people experiencing homelessness and alcohol dependence. Despite a growing evidence base, resistance to MAPs is apparent due to limited knowledge of alcohol harm reduction and the cultural preference for abstinence-based approaches. To address this, service managers working in a not-for-profit organization in Scotland designed and delivered a program of alcohol-specific staff training as part of a larger study exploring the potential implementation of MAPs during the COVID-19 pandemic. Methods: Semi-structured interviews were conducted with 15 service managers and staff regarding their experiences of the training provided. Data were analyzed using Framework Analysis, and Lewin’s model of organizational change was applied to the findings to gain deeper theoretical insight into data relating to staff knowledge, training, and organizational change. Findings: Participants described increased knowledge about alcohol harm reduction and MAPs, as well as increased opportunities for conversations around cultural change. Findings highlight individual- and organizational-level change is required when implementing novel harm reduction interventions like MAPs. Conclusion: The findings have implications for the future implementation of MAPs in homelessness settings. Training can promote staff buy-in, facilitate the involvement of staff within the planning process, and change organizational culture.</p

A mathematical investigation into the uptake kinetics of nanoparticles in vitro.

Nanoparticles have the potential to increase the efficacy of anticancer drugs whilst reducing off-target side effects. However, there remain uncertainties regarding the cellular uptake kinetics of nanoparticles which could have implications for nanoparticle design and delivery. Polymersomes are nanoparticle candidates for cancer therapy which encapsulate chemotherapy drugs. Here we develop a mathematical model to simulate the uptake of polymersomes via endocytosis, a process by which polymersomes bind to the cell surface before becoming internalised by the cell where they then break down, releasing their contents which could include chemotherapy drugs. We focus on two in vitro configurations relevant to the testing and development of cancer therapies: a well-mixed culture model and a tumour spheroid setup. Our mathematical model of the well-mixed culture model comprises a set of coupled ordinary differential equations for the unbound and bound polymersomes and associated binding dynamics. Using a singular perturbation analysis we identify an optimal number of ligands on the polymersome surface which maximises internalised polymersomes and thus intracellular chemotherapy drug concentration. In our mathematical model of the spheroid, a multiphase system of partial differential equations is developed to describe the spatial and temporal distribution of bound and unbound polymersomes via advection and diffusion, alongside oxygen, tumour growth, cell proliferation and viability. Consistent with experimental observations, the model predicts the evolution of oxygen gradients leading to a necrotic core. We investigate the impact of two different internalisation functions on spheroid growth, a constant and a bond dependent function. It was found that the constant function yields faster uptake and therefore chemotherapy delivery. We also show how various parameters, such as spheroid permeability, lead to travelling wave or steady-state solutions

Benthic and hyporheic invertebrate community responses to seasonal flow recession in a groundwater-dominated stream

Natural hydrological variability in lotic ecosystems can include prolonged periods of flow recession. A reduction in discharge is accompanied by abiotic changes in benthic and hyporheic habitats, often including reductions in s habitat availability. Whilst the benthic invertebrate community response to low flows is well documented, little research has considered how the composition of the community within the hyporheic zone is affected. We examined benthic and hyporheic invertebrate community composition during flow recession in a temperate karst stream, at sites with contrasting historic flow permanence regimes. Changes in the benthic invertebrate community composition primarily reflected changes in habitat availability associated with discharge variability; in particular, the population density of the dominant amphipod, Gammarus pulex, increased as the area of submerged benthic sediments declined. Concurrent significant increase in the hyporheic abundance of G. pulex, and moderate increase in the proportion of the total G. pulex population inhabiting the hyporheic zone were recorded. It is postulated that G. pulex migrated into the hyporheic zone to reduce exposure to intensifying biological interactions in the benthic sediments. Increase in the hyporheic abundance of G. pulex was particularly pronounced at sites with historic intermittent flow, which could be attributed to downwelling stream water dominating vertical hydrologic exchange. The increase in G. pulex abundance reduced community diversity in the benthic sediments, but had no apparent detrimental effects on the hyporheic invertebrate assemblages

The Potential for Managed Alcohol Programmes in Scotland during the COVID-19 Pandemic: A Qualitative Exploration of Key Areas for Implementation Using the Consolidated Framework for Implementation Research

People experiencing homelessness and alcohol dependence are at increased risk of a range of harms, including from COVID-19. Managed Alcohol Programmes (MAPs) are an alcohol harm reduction intervention specifically for this group. In this paper we report on qualitative findings of a mixed methods study investigating the potential utility of MAPs during the COVID-19 pandemic in Scotland. Interviews, conducted with 40 participants, explored potential views of implementing MAPs during the pandemic. Theoretically, we drew on the Consolidated Framework for Implementation Research (CFIR) to inform data collection and analysis. Six themes were identified which mapped onto three CFIR domains: perceptions of MAPs and the evidence base; necessary components of MAPs; changing culture of alcohol harm reduction; MAPs as a moral and ethical grey area; addressing a service gap; and securing buy-in and partnership working. Participants were generally positive about MAPs and viewed them as a key intervention to address a service gap. Several necessary components were identified for successful implementation of MAPs. Securing buy-in from a range of stakeholders and partnership working were deemed important. Finally, MAPs require careful, long-term planning before implementation. We conclude that MAPs are needed in Scotland and require long-term funding and appropriate resources to ensure they are successful

A qualitative exploration of the relevance of training provision in planning for implementation of managed alcohol programs within a third sector setting

Background: Managed Alcohol Programs (MAPs) are a harm reduction strategy for people experiencing homelessness and alcohol dependence. Despite a growing evidence base, resistance to MAPs is apparent due to limited knowledge of alcohol harm reduction and the cultural preference for abstinence-based approaches. To address this, service managers working in a not-for-profit organization in Scotland designed and delivered a program of alcohol-specific staff training as part of a larger study exploring the potential implementation of MAPs during the COVID-19 pandemic. Methods: semi-structured interviews were conducted with 15 service managers and staff regarding their experiences of the training provided. Data were analyzed using Framework analysis, and Lewin's model of organizational change was applied to the findings to gain deeper theoretical insight into data relating to staff knowledge, training, and organizational change. Findings: participants described increased knowledge about alcohol harm reduction and MAPs, as well as increased opportunities for conversations around cultural change. Findings highlight individual-and organizational-level change is required when implementing novel harm reduction interventions like MAPs. Conclusion: the findings have implications for the future implementation of MAPs in homelessness settings. training can promote staff buy-in, facilitate the involvement of staff within the planning process, and change organizational culture

The effects of species ortholog and SNP variation on receptors for free fatty acids

Although it is widely assumed that species orthologs of hormone responsive G protein-coupled receptors will be activated by the same endogenously produced ligand(s), variation in potency, particularly in cases where more than one receptor responds to the same hormone, can result in challenges in defining the contribution of individual receptors in different species. This can create considerably greater issues when using synthetic chemical ligands and, in some cases, may result in a complete lack of efficacy of such a ligand when used in animal models of pathophysiology. In man, the concept that distinct responses of individuals to medicines may reflect differences in the ability of such drugs to bind to or activate single nucleotide polymorphism variants of receptors is more established as a concept but, in many cases, clear links between such variants that are associated with disease phenotypes and substantial differences in receptor ligand pharmacology have been more difficult to obtain. Herein, we consider each of these issues for the group of receptors, FFA1-FFA4, defined to be activated by free fatty acids of varying chain length which, based on their production by one tissue or location and action in distinct locations, have been suggested to possess characteristics of ‘hormones’

Exploring the Potential of Implementing Managed Alcohol Programmes to Reduce Risk of COVID-19 Infection and Transmission, and Wider Harms, for People Experiencing Alcohol Dependency and Homelessness in Scotland

People who experience homelessness and alcohol dependency are more vulnerable than the general population to risks/harms relating to COVID-19. This mixed methods study explored stakeholder perspectives concerning the impact of COVID-19 and the potential utility of introducing managed alcohol programmes (MAPs) in Scotland as part of a wider health/social care response for this group. Data sources included: 12 case record reviews; 40 semi-structured qualitative interviews; and meeting notes from a practitioner-researcher group exploring implementation of MAPs within a third sector/not-for-profit organisation. A series of paintings were curated as a novel part of the research process to support knowledge translation. The case note review highlighted the complexity of health problems experienced, in addition to alcohol dependency, including polysubstance use, challenges related to alcohol access/use during lockdown, and complying with stay-at-home rules. Qualitative analysis generated five subthemes under the theme of ‘MAPs as a response to COVID-19′: changes to alcohol supply/use including polysubstance use; COVID-19-related changes to substance use/homelessness services; negative changes to services for people with alcohol problems; the potential for MAPs in the context of COVID-19; and fears and concerns about providing MAPs as a COVID-19 response. We conclude that MAPs have the potential to reduce a range of harms for this group, including COVID-19-related harms

Codesigning a systemic discharge intervention for inpatient mental health settings (MINDS): a protocol for integrating realist evaluation and an engineering-based systems approach

© 2023 The Author(s). Published by BMJ. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Introduction: Transition following discharge from mental health hospital is high risk in terms of relapse, readmission and suicide. Discharge planning supports transition and reduces risk. It is a complex activity involving interacting systemic elements. The codesigning a systemic discharge intervention for inpatient mental health settings (MINDS) study aims to improve the process for people being discharged, their carers/supporters and staff who work in mental health services, by understanding, co-designing and evaluating implementation of a systemic approach to discharge planning. Methods and analysis: The MINDS study integrates realist research and an engineering-informed systems approach across three stages. Stage 1 applies realist review and evaluation using a systems approach to develop programme theories of discharge planning. Stage 2 uses an Engineering Better Care framework to codesign a novel systemic discharge intervention, which will be subjected to process and economic evaluation in stage 3. The programme theories and resulting care planning approach will be refined throughout the study ready for a future clinical trial. MINDS is co-led by an expert by experience, with researchers with lived experience co-leading each stage. Ethics and dissemination: MINDS stage 1 has received ethical approval from Yorkshire & The Humber—Bradford Leeds (Research Ethics Committee (22/YH/0122). Findings from MINDS will be disseminated via high-impact journal publications and conference presentations, including those with service user and mental health professional audiences. We will establish routes to engage with public and service user communities and National Health Service professionals including blogs, podcasts and short videos. Trial registration number: MINDS is funded by the National Institute of Health Research (NIHR 133013) https://fundingawards.nihr.ac.uk/award/NIHR133013. The realist review protocol is registered on PROSPERO. PROSPERO registration number: CRD42021293255.Peer reviewe