Investigating pluripotency and primordial germ cell development in axolotl with a focus on axnanog and axblimp1

The study of pluripotent cells in mouse has revealed a core transcription factor network. Pluripotent cells have not been identified in many non-mammalian organisms, but cells with pluripotent properties are found in axolotl (Ambystoma mexicanum) a urodele amphibian. Similarities, between the morphological processes in amniotes and those in urodeles led to the suggestion that amniotes may have arisen from a urodele-like ancestor. Thus, studying the pluripotency network in axolotl may be key to understanding the evolution of mechanisms governing pluripotency in amniotes. This study describes the investigation of two of the core pluripotency trancription factors, Axnanog and Axoct4. Coexpression of axnanog and axoct4 was detected in the undifferentiated tissues of blastula and gastrula stage embryos, suggesting a conserved role in pluripotency/multipotency. Antisense morpholino oligonucleotides were employed to investigate the function of these two molecules. Gastrulation was disrupted in Axnanog morphant embryos. Additionally, they maintained expression of genes associated with pluripotency and early lineage specification, but only expressed low levels of terminal differentiation markers. There are two explanations for this phenotype, a cell migration defect or a developmental block. Axoct4 morphant embryos had a similar phenotype suggesting that Axoct4 may function in a common pathway. Primordial germ cells (PGCs) are the only cells that retain the ability throughout development to derive all of the tissues of the embryo, upon fertilisation, and these cells express many pluripotency-associated factors. Little is known about PGC development in axolotl. In this study, the roles of Axoct4, Axnanog and Axblimp1 were investigated. Neither Axnanog nor Axoct4 were found to have a role in PGC development. Axblimp1 is unlikely to have a role in PGC specification, as in mouse, but a role in PGC maintenance was not ruled out

Investigating pluripotency and primordial germ cell development in axolotl with a focus on axnanog and axblimp1

The study of pluripotent cells in mouse has revealed a core transcription factor network. Pluripotent cells have not been identified in many non-mammalian organisms, but cells with pluripotent properties are found in axolotl (Ambystoma mexicanum) a urodele amphibian. Similarities, between the morphological processes in amniotes and those in urodeles led to the suggestion that amniotes may have arisen from a urodele-like ancestor. Thus, studying the pluripotency network in axolotl may be key to understanding the evolution of mechanisms governing pluripotency in amniotes. This study describes the investigation of two of the core pluripotency trancription factors, Axnanog and Axoct4. Coexpression of axnanog and axoct4 was detected in the undifferentiated tissues of blastula and gastrula stage embryos, suggesting a conserved role in pluripotency/multipotency. Antisense morpholino oligonucleotides were employed to investigate the function of these two molecules. Gastrulation was disrupted in Axnanog morphant embryos. Additionally, they maintained expression of genes associated with pluripotency and early lineage specification, but only expressed low levels of terminal differentiation markers. There are two explanations for this phenotype, a cell migration defect or a developmental block. Axoct4 morphant embryos had a similar phenotype suggesting that Axoct4 may function in a common pathway. Primordial germ cells (PGCs) are the only cells that retain the ability throughout development to derive all of the tissues of the embryo, upon fertilisation, and these cells express many pluripotency-associated factors. Little is known about PGC development in axolotl. In this study, the roles of Axoct4, Axnanog and Axblimp1 were investigated. Neither Axnanog nor Axoct4 were found to have a role in PGC development. Axblimp1 is unlikely to have a role in PGC specification, as in mouse, but a role in PGC maintenance was not ruled out

The consequences of micro-discretions and boundaries in the social prescribing link worker role in England: a realist evaluation

Background: Social prescribing addresses non-medical factors affecting health and well-being. Link workers arekey to its delivery by connecting people to relevant support, often in the voluntary, community and social enterprisesector. Funding from the National Health Service means that link workers are becoming a common part of primarycare in England.Objective: To explore and understand the implementation of link workers in primary care in England.Design: A realist evaluation addressed the question – When implementing link workers in primary care to sustainoutcomes – what works, for whom, why and in what circumstances?Setting: Link workers and staff associated with seven primary care sites across England.Methods: Researchers spent 3 weeks with each link worker, going to meetings with them, watching them interactwith patients, with healthcare staff and with voluntary, community and social enterprise organisations. In addition,interviews were conducted with 61 patients and 93 professionals (voluntary, community and social enterpriserepresentatives and healthcare staff, including link workers). Follow-up interviews were conducted with 41 patientsand with link workers 9–12 months later. Data were coded and developed into statements to identify how contextaround the link worker triggers mechanisms that lead to intended and unintended outcomes.Results: We found that link workers exercise micro-discretions in their role – actions and advice-giving based onpersonal judgement of a situation, which may not always reflect explicit guidance or protocols. Our analysis highlightedthat micro-discretions engender positive connections (with patients, healthcare staff, the voluntary, community andsocial enterprise sector) and promote buy-in to the link worker role in primary care. Micro-discretions supporteddelivery of person-centred care and enhanced job satisfaction. Data also highlighted that lack of boundaries couldplace link workers at risk of overstepping their remit.Limitations: Our research focused on link workers attached to primary care; findings may not be applicable tothose working in other settings. Data were collected around seven link worker cases, who were selected purposivelyfor variation in terms of geographical spread and how/by whom link workers were employed. However, these linkworkers were predominately white females.Conclusions: Enabling link workers to exercise micro-discretions allows for responsiveness to individual patientneeds but can result in uncertainty and to link workers feeling overstretched

“She’s been a rock”: the function and importance of ‘holding’ by social prescribing link workers in primary care in England: findings from a realist evaluation.

Social prescribing link workers are new roles in English primary care. One of their intended functions is to address the increasing number of patients with conditions influenced by the wider, social determinants of health. Their main purpose is to connect people to community resources to meet their non-medical needs. However, our research reveals that link workers provide not only connections, but also what we have described as ‘holding’ for patients who have complex needs, who lack informal networks of support or who are waiting to access services. We explore the concept of holding, its meaning and significance in this context and its consequences.As part of a realist evaluation, we observed seven link workers in GP practices in England during focussed ethnographies over a three-week period. We took field notes and interviewed 61 patients and 93 healthcare professionals. Nine to twelve months later we carried out follow-up interviews with 41 patients, seven link workers and a link worker manager. We identified four functions of holding: supporting patients waiting for services, sustaining patients as they prepare for change, reducing the emotional burden of primary healthcare professionals, and bearing witness to patients’ distress. Holding appears to be a vital, but often overlooked aspect of social prescribing. Patients benefit from having a reliable and consistent person to support their emotional needs. However, similar to the impact of holding on other primary care professionals, there are unintended consequences: some link workers exceed their capacity, become over-burdened, experience burnout, and leave their job. Recognizing the importance of holding and understanding its role in link workers' primary care responsibilities are critical. If holding work is accepted as a role for link workers, providing training and support for them should be prioritized to ensure successful implementation and positive outcomes for patients, link workers and primary healthcare

Stochastic specification of primordial germ cells from mesoderm precursors in axolotl embryos

A common feature of development in most vertebrate models is the early segregation of the germ line from the soma. For example, in Xenopus and zebrafish embryos primordial germ cells (PGCs) are specified by germ plasm that is inherited from the egg; in mice, Blimp1 expression in the epiblast mediates the commitment of cells to the germ line. How these disparate mechanisms of PGC specification evolved is unknown. Here, in order to identify the ancestral mechanism of PGC specification in vertebrates, we studied PGC specification in embryos from the axolotl (Mexican salamander), a model for the tetrapod ancestor. In the axolotl, PGCs develop within mesoderm, and classic studies have reported their induction from primitive ectoderm (animal cap). We used an axolotl animal cap system to demonstrate that signalling through FGF and BMP4 induces PGCs. The role of FGF was then confirmed in vivo. We also showed PGC induction by Brachyury, in the presence of BMP4. These conditions induced pluripotent mesodermal precursors that give rise to a variety of somatic cell types, in addition to PGCs. Irreversible restriction of the germ line did not occur until the mid-tailbud stage, days after the somatic germ layers are established. Before this, germline potential was maintained by MAP kinase signalling. We propose that this stochastic mechanism of PGC specification, from mesodermal precursors, is conserved in vertebrates

Experiences of integrating social prescribing link workers into primary care in England: Bolting on, fitting in or belonging

Background: Following the 2019 NHS Long-Term Plan, link workers (LWs) have been employedacross primary care in England to deliver social prescribing (SP).Aim: To understand and explain how the LW role is being implemented in primary care in England.Design and setting: Realist evaluation undertaken in England.Method: Focused ethnographies around seven LWs from different parts of England. As part of this,we interviewed 61 patients and 93 professionals from healthcare and the voluntary, community andsocial enterprise (VCSE) sector. We reinterviewed 41 patients, seven LWs and a LW manager 9-12months after their first interview.Results: We developed four concepts around how LWs are integrated (or not) within primary care:Centralising or diffusing power; Forging an identity in general practice; Demonstrating effect;Building a facilitative infrastructure. These concepts informed the development of a programmetheory around a continuum of integration of LWs into primary care – from being ‘bolted on’ toexisting provision, without much consideration, to ‘fitting in’, shaping what is delivered to beaccommodating, through to ‘belonging’, whereby they are accepted as a legitimate source ofsupport, making a valued contribution to patients’ broader well-being.Conclusion: SP was introduced into primary care to promote greater attention to the full range offactors affecting patients’ health and well-being, beyond biomedicine. For that to happen, ouranalysis highlights the need for a whole system approach to defining, delivering and maintaining thisnew part of practice

NANOG is required to establish the competence for germ-layer differentiation in the basal tetrapod axolotl

Pluripotency defines the unlimited potential of individual cells of vertebrate embryos, from which all adult somatic cells and germ cells are derived. Understanding how the programming of pluripotency evolved has been obscured in part by a lack of data from lower vertebrates; in model systems such as frogs and zebrafish, the function of the pluripotency genes NANOG and POU5F1 have diverged. Here, we investigated how the axolotl ortholog of NANOG programs pluripotency during development. Axolotl NANOG is absolutely required for gastrulation and germ-layer commitment. We show that in axolotl primitive ectoderm (animal caps; ACs) NANOG and NODAL activity, as well as the epigenetic modifying enzyme DPY30, are required for the mass deposition of H3K4me3 in pluripotent chromatin. We also demonstrate that all 3 protein activities are required for ACs to establish the competency to differentiate toward mesoderm. Our results suggest the ancient function of NANOG may be establishing the competence for lineage differentiation in early cells. These observations provide insights into embryonic development in the tetrapod ancestor from which terrestrial vertebrates evolved. [Abstract copyright: Copyright: © 2023 Simpson et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Percutaneous revascularization for ischemic left ventricular dysfunction: Cost-effectiveness analysis of the REVIVED-BCIS2 trial

BACKGROUND: Percutaneous coronary intervention (PCI) is frequently undertaken in patients with ischemic left ventricular systolic dysfunction. The REVIVED (Revascularization for Ischemic Ventricular Dysfunction)-BCIS2 (British Cardiovascular Society-2) trial concluded that PCI did not reduce the incidence of all-cause death or heart failure hospitalization; however, patients assigned to PCI reported better initial health-related quality of life than those assigned to optimal medical therapy (OMT) alone. The aim of this study was to assess the cost-effectiveness of PCI+OMT compared with OMT alone. METHODS: REVIVED-BCIS2 was a prospective, multicenter UK trial, which randomized patients with severe ischemic left ventricular systolic dysfunction to either PCI+OMT or OMT alone. Health care resource use (including planned and unplanned revascularizations, medication, device implantation, and heart failure hospitalizations) and health outcomes data (EuroQol 5-dimension 5-level questionnaire) on each patient were collected at baseline and up to 8 years post-randomization. Resource use was costed using publicly available national unit costs. Within the trial, mean total costs and quality-adjusted life-years (QALYs) were estimated from the perspective of the UK health system. Cost-effectiveness was evaluated using estimated mean costs and QALYs in both groups. Regression analysis was used to adjust for clinically relevant predictors. RESULTS: Between 2013 and 2020, 700 patients were recruited (mean age: PCI+OMT=70 years, OMT=68 years; male (%): PCI+OMT=87, OMT=88); median follow-up was 3.4 years. Over all follow-ups, patients undergoing PCI yielded similar health benefits at higher costs compared with OMT alone (PCI+OMT: 4.14 QALYs, £22 352; OMT alone: 4.16 QALYs, £15 569; difference: −0.015, £6782). For both groups, most health resource consumption occurred in the first 2 years post-randomization. Probabilistic results showed that the probability of PCI being cost-effective was 0. CONCLUSIONS: A minimal difference in total QALYs was identified between arms, and PCI+OMT was not cost-effective compared with OMT, given its additional cost. A strategy of routine PCI to treat ischemic left ventricular systolic dysfunction does not seem to be a justifiable use of health care resources in the United Kingdom

Arrhythmia and death following percutaneous revascularization in ischemic left ventricular dysfunction: Prespecified analyses from the REVIVED-BCIS2 trial

BACKGROUND: Ventricular arrhythmia is an important cause of mortality in patients with ischemic left ventricular dysfunction. Revascularization with coronary artery bypass graft or percutaneous coronary intervention is often recommended for these patients before implantation of a cardiac defibrillator because it is assumed that this may reduce the incidence of fatal and potentially fatal ventricular arrhythmias, although this premise has not been evaluated in a randomized trial to date. METHODS: Patients with severe left ventricular dysfunction, extensive coronary disease, and viable myocardium were randomly assigned to receive either percutaneous coronary intervention (PCI) plus optimal medical and device therapy (OMT) or OMT alone. The composite primary outcome was all-cause death or aborted sudden death (defined as an appropriate implantable cardioverter defibrillator therapy or a resuscitated cardiac arrest) at a minimum of 24 months, analyzed as time to first event on an intention-to-treat basis. Secondary outcomes included cardiovascular death or aborted sudden death, appropriate implantable cardioverter defibrillator (ICD) therapy or sustained ventricular arrhythmia, and number of appropriate ICD therapies. RESULTS: Between August 28, 2013, and March 19, 2020, 700 patients were enrolled across 40 centers in the United Kingdom. A total of 347 patients were assigned to the PCI+OMT group and 353 to the OMT alone group. The mean age of participants was 69 years; 88% were male; 56% had hypertension; 41% had diabetes; and 53% had a clinical history of myocardial infarction. The median left ventricular ejection fraction was 28%; 53.1% had an implantable defibrillator inserted before randomization or during follow-up. All-cause death or aborted sudden death occurred in 144 patients (41.6%) in the PCI group and 142 patients (40.2%) in the OMT group (hazard ratio, 1.03 [95% CI, 0.82–1.30]; P =0.80). There was no between-group difference in the occurrence of any of the secondary outcomes. CONCLUSIONS: PCI was not associated with a reduction in all-cause mortality or aborted sudden death. In patients with ischemic cardiomyopathy, PCI is not beneficial solely for the purpose of reducing potentially fatal ventricular arrhythmias. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01920048