A Lumped-Parameter Model of the Cardiovascular System Response for Evaluating Automated Fluid Resuscitation Systems.

Physiological closed-loop controlled (PCLC) medical devices, such as those designed for blood pressure regulation, can be tested for safety and efficacy in real-world clinical settings. However, relying solely on limited animal and clinical studies may not capture the diverse range of physiological conditions. Credible mathematical models can complement these studies by allowing the testing of the device against simulated patient scenarios. This research involves the development and validation of a low-order lumped-parameter mathematical model of the cardiovascular system's response to fluid perturbation. The model takes rates of hemorrhage and fluid infusion as inputs and provides hematocrit and blood volume, heart rate, stroke volume, cardiac output and mean arterial blood pressure as outputs. The model was calibrated using data from 27 sheep subjects, and its predictive capability was evaluated through a leave-one-out cross-validation procedure, followed by independent validation using 12 swine subjects. Our findings showed small model calibration error against the training dataset, with the normalized root-mean-square error (NRMSE) less than 10% across all variables. The mathematical model and virtual patient cohort generation tool demonstrated a high level of predictive capability and successfully generated a sufficient number of subjects that closely resembled the test dataset. The average NRMSE for the best virtual subject, across two distinct samples of virtual subjects, was below 12.7% and 11.9% for the leave-one-out cross-validation and independent validation dataset. These findings suggest that the model and virtual cohort generator are suitable for simulating patient populations under fluid perturbation, indicating their potential value in PCLC medical device evaluation.

TNFR1 signaling converging on FGF14 controls neuronal hyperactivity and sickness behavior in experimental cerebral malaria.

BACKGROUND: Excess tumor necrosis factor (TNF) is implicated in the pathogenesis of hyperinflammatory experimental cerebral malaria (eCM), including gliosis, increased levels of fibrin(ogen) in the brain, behavioral changes, and mortality. However, the role of TNF in eCM within the brain parenchyma, particularly directly on neurons, remains underdefined. Here, we investigate electrophysiological consequences of eCM on neuronal excitability and cell signaling mechanisms that contribute to observed phenotypes. METHODS: The split-luciferase complementation assay (LCA) was used to investigate cell signaling mechanisms downstream of tumor necrosis factor receptor 1 (TNFR1) that could contribute to changes in neuronal excitability in eCM. Whole-cell patch-clamp electrophysiology was performed in brain slices from eCM mice to elucidate consequences of infection on CA1 pyramidal neuron excitability and cell signaling mechanisms that contribute to observed phenotypes. Involvement of identified signaling molecules in mediating behavioral changes and sickness behavior observed in eCM were investigated in vivo using genetic silencing. RESULTS: Exploring signaling mechanisms that underlie TNF-induced effects on neuronal excitability, we found that the complex assembly of fibroblast growth factor 14 (FGF14) and the voltage-gated Na+ (Nav) channel 1.6 (Nav1.6) is increased upon tumor necrosis factor receptor 1 (TNFR1) stimulation via Janus Kinase 2 (JAK2). On account of the dependency of hyperinflammatory experimental cerebral malaria (eCM) on TNF, we performed patch-clamp studies in slices from eCM mice and showed that Plasmodium chabaudi infection augments Nav1.6 channel conductance of CA1 pyramidal neurons through the TNFR1-JAK2-FGF14-Nav1.6 signaling network, which leads to hyperexcitability. Hyperexcitability of CA1 pyramidal neurons caused by infection was mitigated via an anti-TNF antibody and genetic silencing of FGF14 in CA1. Furthermore, knockdown of FGF14 in CA1 reduced sickness behavior caused by infection. CONCLUSIONS: FGF14 may represent a therapeutic target for mitigating consequences of TNF-mediated neuroinflammation.

Examining the Role of Hypothalamus-Derived Neuromedin-U (NMU) in Bone Remodeling of Rats.

Global loss of the neuropeptide Neuromedin-U (NMU) is associated with increased bone formation and high bone mass in male and female mice by twelve weeks of age, suggesting that NMU suppresses osteoblast differentiation and/or activity in vivo. NMU is highly expressed in numerous anatomical locations including the skeleton and the hypothalamus. This raises the possibility that NMU exerts indirect effects on bone remodeling from an extra-skeletal location such as the brain. Thus, in the present study we used microinjection to deliver viruses carrying short-hairpin RNA designed to knockdown Nmu expression in the hypothalamus of 8-week-old male rats and evaluated the effects on bone mass in the peripheral skeleton. Quantitative RT-PCR confirmed approximately 92% knockdown of Nmu in the hypothalamus. However, after six weeks, micro computed tomography on tibiae from Nmu-knockdown rats demonstrated no significant change in trabecular or cortical bone mass as compared to controls. These findings are corroborated by histomorphometric analyses which indicate no differences in osteoblast or osteoclast parameters between controls and Nmu-knockdown samples. Collectively, these data suggest that hypothalamus-derived NMU does not regulate bone remodeling in the postnatal skeleton. Future studies are necessary to delineate the direct versus indirect effects of NMU on bone remodeling.

Aqueous Solid Formation Kinetics in High-Pressure Methane at Trace Water Concentrations.

Natural gas containing trace amounts of water is frequently liquefied at conditions where aqueous solids are thermodynamically stable. However, no data are available to describe the kinetics of aqueous solid formation at these conditions. Here, we present experimental measurements of both solid formation kinetics and solid-fluid equilibrium for trace concentrations of (12 ± 0.7) ppm water in methane using a stirred, high-pressure apparatus and visual microscopy. Along isochoric pathways with cooling rates around 1 K·min-1, micron-scale aqueous solids were observed to form at subcoolings of (0.3-8.6) K, relative to an average equilibrium melting temperature of (253 ± 1.9) K at (8.9 ± 0.08) MPa; these data are consistent with predicted methane hydrate dissociation conditions within the uncertainty of both the experiment and model. The 36 measured formation events were used to construct a cumulative formation probability distribution, which was then fitted with a model from Classical Nucleation Theory, enabling the extraction of kinetic and thermodynamic nucleation parameters. While the resulting nucleation parameter values were comparable to those published for methane hydrate formation in bulk-water systems, the observed growth kinetics were distinctly different with only a small percentage of the water in the system converting into micron-scale solids over the experimental time scale. These results may help explain how cryogenic heat exchangers in liquefied natural gas facilities can operate for long periods without blockages forming despite being at very high subcoolings for aqueous solids.

A Mathematical Model for Simulation of Vasoplegic Shock and Vasopressor Therapy.

OBJECTIVE: To develop a high-fidelity mathematical model intended to replicate the cardiovascular (CV) responses of a critically ill patient to vasoplegic shock-induced hypotension and vasopressor therapy. METHODS: The mathematical model consists of a lumped-parameter CV physiology model with baroreflex modulation feedback and a phenomenological dynamic dose-response model of a vasopressor. The adequacy of the proposed mathematical model was investigated using an experimental dataset acquired from 10 pigs receiving phenylephrine (PHP) therapy after vasoplegic shock induced via sodium nitroprusside (SNP). RESULTS: Upon calibration, the mathematical model could (i) faithfully replicate the effects of PHP on dynamic changes in blood pressure (BP), cardiac output (CO), and systemic vascular resistance (SVR) (root-mean-squared errors between measured and calibrated mathematical responses: mean arterial BP 2.5+/-1.0 mmHg, CO 0.2+/-0.1 lpm, SVR 2.4+/-1.5 mmHg/lpm; r value: mean arterial BP 0.96+/-0.01, CO 0.65+/-0.45, TPR 0.92+/-0.10) and (ii) predict physiologically plausible behaviors of unmeasured internal CV variables as well as secondary baroreflex modulation effects. CONCLUSION: This mathematical model is perhaps the first of its kind that can comprehensively replicate both primary (i.e., direct) and secondary (i.e., baroreflex modulation) effects of a vasopressor drug on an array of CV variables, rendering it ideally suited to pre-clinical virtual evaluation of the safety and efficacy of closed-loop control algorithms for autonomous vasopressor administration once it is extensively validated. SIGNIFICANCE: This mathematical model architecture incorporating both direct and baroreflex modulation effects may generalize to serve as part of an effective platform for high-fidelity in silico simulation of CV responses to vasopressors during vasoplegic shock.

Contesting constructs and interrogating research methods: Re-analysis of qualitative data from a hospital-based case study of self-harm management and prevention practices.

Discourses of self-harm, and also suicide, are often underpinned by a central tenet: prevention is the priority. This belief is seemingly so inscribed in research that it is rarely interrogated. The present paper re-analyses qualitative data from a hospital-based study of self-harm management and prevention practice. It aims to reflect upon, and disrupt, the authors' latent assumptions about the construct of 'prevention', while reflecting on the research method used. Twenty-five individuals participated in semi-structured interviews: healthcare and affiliated professionals (n = 14); parents and carers (n = 8); and children and young people (aged 9-16 years) who had presented to an emergency department for self-harm, with or without suicidal intent (n = 3). We offer two central discursive considerations: (1) Self-harm prevention is largely an unintelligible concept, having to be reflexively constructed in situ. As such, it is questionable whether it makes sense to discuss the prevention of this amorphous and dynamic phenomenon, which cannot always be disentangled from everyday life; (2) Interviews entail significant biographical work for participants, notably the performance of personal and professional competence for the audience. These interactional dynamics offer a glimpse into the priorities, meanings and needs for participants in relation to self-harm. Together these considerations provide useful insights into how the interview method can serve as both a limiting and illuminating site of knowledge creation.

Combined nicotinamide N-methyltransferase inhibition and reduced-calorie diet normalizes body composition and enhances metabolic benefits in obese mice.

Obesity is a large and growing global health problem with few effective therapies. The present study investigated metabolic and physiological benefits of nicotinamide N-methyltransferase inhibitor (NNMTi) treatment combined with a lean diet substitution in diet-induced obese mice. NNMTi treatment combined with lean diet substitution accelerated and improved body weight and fat loss, increased whole-body lean mass to body weight ratio, reduced liver and epididymal white adipose tissue weights, decreased liver adiposity, and improved hepatic steatosis, relative to a lean diet substitution alone. Importantly, combined lean diet and NNMTi treatment normalized body composition and liver adiposity parameters to levels observed in age-matched lean diet control mice. NNMTi treatment produced a unique metabolomic signature in adipose tissue, with predominant increases in ketogenic amino acid abundance and alterations to metabolites linked to energy metabolic pathways. Taken together, NNMTi treatment's modulation of body weight, adiposity, liver physiology, and the adipose tissue metabolome strongly support it as a promising therapeutic for obesity and obesity-driven comorbidities.

Theorising health professionals' prevention and management practices with children and young people experiencing self-harm: a qualitative hospital-based case study.

Self-harm in young people remains a significant concern. Studies of emergency departments have centred on negative professional attitudes. There has been limited interrogation and theorisation of what drives such attitudes, and the contexts that sustain them. Adopting a complex systems lens, this study aimed to explore how systems shape professional and patient interactions. It draws upon interviews with healthcare and affiliated professionals (n = 14) in a UK case study hospital, with primary focus on the emergency department. Data were analysed using a thematic approach and the principles of grounded theory. Four themes emerged, with the first three centralising how professionals' practices operate within: (1) a framework of risk management; (2) expectations of progressing patients through the care pathway; and (3) a culture of specialist expertise, with resulting uncertainty about who is responsible for self-harm. The fourth theme considers barriers to system change. A small number of participants described efforts to enact positive modifications to practices, but these were frustrated by entrenched system structures. The potential detrimental impacts for patient care and professional wellbeing are considered. Future practice needs systemic action to support professionals in treating patients experiencing self-harm, while future research requires more ethnographic explorations of the complex system in situ.

Chemotherapy decision-making in advanced lung cancer: a prospective qualitative study.

OBJECTIVE: To study how treatment decisions are made alongside the lung cancer clinical pathway. METHODS: A prospective, multicentre, multimethods, five-stage, qualitative study. Mediated discourse, thematic, framework and narrative analysis were used to analyse the transcripts. RESULTS: 51 health professionals, 15 patients with advanced lung cancer, 15 family members and 18 expert stakeholders were recruited from three UK NHS trusts. Multidisciplinary team (MDT) members constructed treatment recommendations around patient performance status, pathology, clinical information and imaging. Information around patients' social context, needs and preferences were limited. The provisional nature of MDTs treatment recommendations was not always linked to future discussions with the patient along the pathway, that is, patients' interpretation of their prognosis, treatment discussions occurring prior to seeing the oncologist. This together with the rapid disease trajectory placed additional stress on the oncologist, who had to introduce a different treatment option from that recommended by the MDT or patient's expectations. Palliative treatment was not referred to explicitly as such, due to its potential for confusion. Patients were unaware of the purpose of each consultation and did not fully understand the non-curative intent of treatment pathways. Patients' priorities were framed around social and family needs, such as being able to attend a family event. CONCLUSION: Missed opportunities for information giving, affect both clinicians and patients; the pathway for patients with non-small cell lung cancer focuses on clinical management at the expense of patient-centred care. Treatment decisions are a complex process and patients draw conclusions from healthcare interactions prior to the oncology clinic, which prioritises aggressive treatment and influences decisions.

Patients' Experiences of Emergency Hospital Care Following Self-Harm: Systematic Review and Thematic Synthesis of Qualitative Research.

Rates of hospital presentation for self-harm have increased in recent years, and although clinical practice guidelines on clinical provision prioritize positive patient experiences, the quality of provision remains variable. This systematic review provides an updated and extended synthesis of qualitative research on the following: (a) patients' experiences of treatment following presentation to hospital; and (b) patients' perceptions of the impact of treatment on recurrent self-harm and/or suicidal ideation, and future help-seeking. Twenty-six studies were identified for inclusion in the final synthesis. Three meta-themes emerged: (a) individuals undertake extensive identity work when presenting with self-harm, navigating the process of becoming a patient, and negotiating the type of patient they want to be; (b) care ranges from gentle to hostile, with care at admission and discharge being particularly disorientating; and (c) negative experiences of clinical treatment may increase future self-harm. Emerging research gaps include the need for further theoretically informed qualitative research in this area.

Considerations and recommendations for conducting qualitative research interviews with palliative and end-of-life care patients in the home setting: a consensus paper.

OBJECTIVES: To present and discuss the views of researchers at an academic palliative care research centre on research encounters with terminally ill patients in the home setting and to generate a list of recommendations for qualitative researchers working in palliative and end-of-life care. METHODS: Eight researchers took part in a consensus meeting to discuss their experiences of undertaking qualitative interviews. The researchers were of varying backgrounds and all reported having experience in interviewing terminally ill patients, and all but one had experience of interviewing patients in their home environment. RESULTS: The main areas discussed by researchers included: whether participation in end-of-life research unintentionally becomes a therapeutic experience or an ethical concern; power relationships between terminally ill patients and researchers; researcher reflexivity and reciprocity; researchers' training needs. Qualitative methods can complement the home environment; however, it can raise ethical and practical challenges, which can be more acute in the case of research undertaken with palliative and patients at the end-of-life. CONCLUSIONS: The ethical and practical challenges researchers face in this context has the potential to place both participant and researcher at risk for their physical and psychological well-being. We present a set of recommendations for researchers to consider prior to embarking on qualitative research in this context and advocate researchers in this field carefully consider the issues presented on a study-by-study basis.

Gaining an accurate reflection of the reality of palliative care through the use of free-text feedback in questionnaires: the AFTER study.

BACKGROUND: In healthcare, many service evaluation questionnaires use free-text boxes without formal mechanisms for analysis. Patients and carers spend time documenting concerns that are often ignored or managed locally in an ad hoc manner. Currently, palliative care experiences of patients and carers in Wales are measured using a service evaluation questionnaire, comprising both closed and open-ended questions. Previous research, exploring free-text responses from this questionnaire, suggests that questionnaire refinement should accommodate service users' expressed priorities and concerns, and highlights the need to incorporate free-text data analysis strategies during study design. METHODS: Results from a previous analysis of 596 free-text responses provided the basis for an expert consensus day, where the current service evaluation questionnaire was refined. The refined version was tested during cognitive interviews with patients (n=10) and carers (n=7) receiving palliative care from 1 of 2 UK hospices. Data were analysed thematically. RESULTS: Interviews highlighted minor areas for change within the questionnaire and provided broader insight into patients' experiences of palliative care services. Patients and carers place an emphasis on simplifying language, decreasing the numeric response range and reducing written instructions; relying instead on visual cues, including formatting and layout. Findings highlighted the importance patients attached to providing meaningful free-text contributions. CONCLUSIONS: Questionnaire refinement should use the patient perspective to effectively facilitate respondent understanding, pertinence and usability. The importance of employing data analysis strategies during questionnaire design may reduce research waste, thus enabling a better interrogation of service provision.

Small-Molecule Neuromedin U Receptor 2 Agonists Suppress Food Intake and Decrease Visceral Fat in Animal Models.

Obesity is a growing public health concern, with 37.5% of the adult population in need of therapeutics that are more efficacious with a better side effect profile. An innovative target in this regard is neuromedin U, a neuropeptide shown to suppress food intake and attenuate weight gain in animal models. These effects of neuromedin U on feeding behavior are thought to be related to agonism at the centrally expressed neuromedin U receptor 2 (NMUR2). As peptides present unique challenges that limit their therapeutic potential, the discovery of small-molecule NMUR2 agonists is needed to validate the targets therapeutic value, but to date, none have been evaluated in any animal model of disease. We therefore assessed two small-molecule NMUR2 agonists for their in vitro signaling and their in vivo efficacy. The NMUR2 agonists were synthesized and both NMUR2 agonists, NY0116 and NY0128, decreased cAMP while stimulating calcium signaling in stably expressing NMUR2 HEK293 cells. When small-molecule NMUR2 agonists were tested in vivo, acute administration significantly decreased high-fat diet consumption. Repeated administration of the compounds decreased body weight and more specifically, decreased the percentage of visceral adipose tissue (VAT) in obese mice. These results have confirmed small-molecule NMUR2 agonists are efficacious in animal models to decrease fat content, food intake, and body weight, suggesting NMUR2 is a promising therapeutic target for metabolic disorders.

Development of an intervention to support patients and clinicians with advanced lung cancer when considering systematic anticancer therapy: protocol for the PACT study.

INTRODUCTION: Patient-centred care is essential to the delivery of healthcare; however, this necessitates direct patient involvement in clinical decision-making and can be challenging for patients diagnosed with advanced non-small cell lung cancer where there may be misunderstanding of the extent of disease, prognosis and aims of treatment. In this context, decisions are complex and there is a need to balance the risks and benefits, including treatment with palliative intent. The aim of the PACT study is to identify the information and decision support needs of patients, leading to the development of an intervention to support patients with advanced lung cancer when considering treatment options. METHODS AND ANALYSIS: PACT is a five-stage, multimethod and multicentre study. Participants: Patients and health professionals will be recruited from three health boards. Methods: Non-participant observation of multidisciplinary team meetings (n=12) will be used to determine patients' allocation to treatment pathways (stage I). Non-participant observation of patient-clinician consultations (n=20-30) will be used to explore communication of treatment options and decision-making. Extent of participation in decision-making will be assessed using the Observing Patient Involvement in Shared Decision-Making tool. Interviews with patients (stage III) and their clinicians (stage IV) will explore the perception of treatment options and involvement in decision-making. Based on stages I-IV, an expert consensus meeting will finalise the content and format of the intervention. Cognitive interviews with patients will then determine the face validity of the intervention (stage V). Analysis: analysis will be according to data type and research question and will include mediated discourse analysis, thematic analysis, framework analysis and interpretative phenomenological analysis. ETHICS AND DISSEMINATION: Ethical approval has been granted. The study findings will contribute to and promote shared and informed decision-making in the best interest of patients and prudent healthcare. We therefore aim to disseminate results via relevant respiratory, oncology and palliative care journals and conferences.

Gamma-Aminobutyric Acidergic Projections From the Dorsal Raphe to the Nucleus Accumbens Are Regulated by Neuromedin U.

BACKGROUND: Neuromedin U (NMU) is a neuropeptide enriched in the nucleus accumbens shell (NAcSh), a brain region associated with reward. While NMU and its receptor, NMU receptor 2 (NMUR2), have been studied for the ability to regulate food reward, NMU has not been studied in the context of drugs of abuse (e.g., cocaine). Furthermore, the neuroanatomical pathways that express NMUR2 and its ultrastructural localization are unknown. METHODS: Immunohistochemistry was used to determine the synaptic localization of NMUR2 in the NAcSh and characterize which neurons express this receptor (n = 17). The functional outcome of NMU on NMUR2 was examined using microdialysis (n = 16). The behavioral effects of NMU microinjection directly to the NAcSh were investigated using cocaine-evoked locomotion (n = 93). The specific effects of NMUR2 knockdown on cocaine-evoked locomotion were evaluated using viral-mediated RNA interference (n = 40). RESULTS: NMUR2 is localized to presynaptic gamma-aminobutyric acidergic nerve terminals in the NAcSh originating from the dorsal raphe nucleus. Furthermore, NMU microinjection to the NAcSh decreased local gamma-aminobutyric acid concentrations. Next, we evaluated the effects of NMU microinjection on behavioral sensitization to cocaine. When repeatedly administered throughout the sensitization regimen, NMU attenuated cocaine-evoked hyperactivity. Additionally, small hairpin RNA-mediated knockdown of presynaptic NMUR2 in the NAcSh using a retrograde viral vector potentiated cocaine sensitization. CONCLUSIONS: Together, these data reveal that NMUR2 modulates a novel gamma-aminobutyric acidergic pathway from the dorsal raphe nucleus to the NAcSh to influence behavioral responses to cocaine.

Protein kinase A regulates caspase-9 activation by Apaf-1 downstream of cytochrome c.

The cyclic AMP signal transduction pathway modulates apoptosis in diverse cell types, although the mechanism is poorly understood. A critical component of the intrinsic apoptotic pathway is caspase-9, which is activated by Apaf-1 in the apoptosome, a large complex assembled in response to release of cytochrome c from mitochondria. Caspase-9 cleaves and activates effector caspases, predominantly caspase-3, resulting in the demise of the cell. Here we identified a distinct mechanism by which cyclic AMP regulates this apoptotic pathway through activation of protein kinase A. We show that protein kinase A inhibits activation of caspase-9 and caspase-3 downstream of cytochrome c in Xenopus egg extracts and in a human cell-free system. Protein kinase A directly phosphorylates human caspase-9 at serines 99, 183, and 195. However, mutational analysis demonstrated that phosphorylation at these sites is not required for the inhibitory effect of protein kinase A on caspase-9 activation. Importantly, protein kinase A inhibits cytochrome c-dependent recruitment of procaspase-9 to Apaf-1 but not activation of caspase-9 by a constitutively activated form of Apaf-1. These data indicate that extracellular signals that elevate cyclic AMP and activate protein kinase A may suppress apoptosis by inhibiting apoptosome formation downstream of cytochrome c release from mitochondria.