Mechanisms of retinoic acid signalling and its roles in organ and limb development.

Retinoic acid (RA) signalling has a central role during vertebrate development. RA synthesized in specific locations regulates transcription by interacting with nuclear RA receptors (RARs) bound to RA response elements (RAREs) near target genes. RA was first implicated in signalling on the basis of its teratogenic effects on limb development. Genetic studies later revealed that endogenous RA promotes forelimb initiation by repressing fibroblast growth factor 8 (Fgf8). Insights into RA function in the limb serve as a paradigm for understanding how RA regulates other developmental processes. In vivo studies have identified RAREs that control repression of Fgf8 during body axis extension or activation of homeobox (Hox) genes and other key regulators during neuronal differentiation and organogenesis.

Id genes are essential for early heart formation.

Deciphering the fundamental mechanisms controlling cardiac specification is critical for our understanding of how heart formation is initiated during embryonic development and for applying stem cell biology to regenerative medicine and disease modeling. Using systematic and unbiased functional screening approaches, we discovered that the Id family of helix-loop-helix proteins is both necessary and sufficient to direct cardiac mesoderm formation in frog embryos and human embryonic stem cells. Mechanistically, Id proteins specify cardiac cell fate by repressing two inhibitors of cardiogenic mesoderm formation-Tcf3 and Foxa2-and activating inducers Evx1, Grrp1, and Mesp1. Most importantly, CRISPR/Cas9-mediated ablation of the entire Id (Id1-4) family in mouse embryos leads to failure of anterior cardiac progenitor specification and the development of heartless embryos. Thus, Id proteins play a central and evolutionarily conserved role during heart formation and provide a novel means to efficiently produce cardiovascular progenitors for regenerative medicine and drug discovery applications.

Characterisation and prion transmission study in mice with genetic reduction of sporadic Creutzfeldt-Jakob disease risk gene Stx6.

Sporadic Creutzfeldt-Jakob disease (sCJD), the most common human prion disease, is thought to occur when the cellular prion protein (PrPC) spontaneously misfolds and assembles into prion fibrils, culminating in fatal neurodegeneration. In a genome-wide association study of sCJD, we recently identified risk variants in and around the gene STX6, with evidence to suggest a causal increase of STX6 expression in disease-relevant brain regions. STX6 encodes syntaxin-6, a SNARE protein primarily involved in early endosome to trans-Golgi network retrograde transport. Here we developed and characterised a mouse model with genetic depletion of Stx6 and investigated a causal role of Stx6 expression in mouse prion disease through a classical prion transmission study, assessing the impact of homozygous and heterozygous syntaxin-6 knockout on disease incubation periods and prion-related neuropathology. Following inoculation with RML prions, incubation periods in Stx6-/- and Stx6+/- mice differed by 12 days relative to wildtype. Similarly, in Stx6-/- mice, disease incubation periods following inoculation with ME7 prions also differed by 12 days. Histopathological analysis revealed a modest increase in astrogliosis in ME7-inoculated Stx6-/- animals and a variable effect of Stx6 expression on microglia activation, however no differences in neuronal loss, spongiform change or PrP deposition were observed at endpoint. Importantly, Stx6-/- mice are viable and fertile with no gross impairments on a range of neurological, biochemical, histological and skeletal structure tests. Our results provide some support for a pathological role of Stx6 expression in prion disease, which warrants further investigation in the context of prion disease but also other neurodegenerative diseases considering syntaxin-6 appears to have pleiotropic risk effects in progressive supranuclear palsy and Alzheimer's disease.

TDP-43-M323K causes abnormal brain development and progressive cognitive and motor deficits associated with mislocalised and increased levels of TDP-43.

TDP-43 pathology is found in several neurodegenerative disorders, collectively referred to as "TDP-43 proteinopathies". Aggregates of TDP-43 are present in the brains and spinal cords of >97% of amyotrophic lateral sclerosis (ALS), and in brains of ∼50% of frontotemporal dementia (FTD) patients. While mutations in the TDP-43 gene (TARDBP) are usually associated with ALS, many clinical reports have linked these mutations to cognitive impairments and/or FTD, but also to other neurodegenerative disorders including Parkinsonism (PD) or progressive supranuclear palsy (PSP). TDP-43 is a ubiquitously expressed, highly conserved RNA-binding protein that is involved in many cellular processes, mainly RNA metabolism. To investigate systemic pathological mechanisms in TDP-43 proteinopathies, aiming to capture the pleiotropic effects of TDP-43 mutations, we have further characterised a mouse model carrying a point mutation (M323K) within the endogenous Tardbp gene. Homozygous mutant mice developed cognitive and behavioural deficits as early as 3 months of age. This was coupled with significant brain structural abnormalities, mainly in the cortex, hippocampus, and white matter fibres, together with progressive cortical interneuron degeneration and neuroinflammation. At the motor level, progressive phenotypes appeared around 6 months of age. Thus, cognitive phenotypes appeared to be of a developmental origin with a mild associated progressive neurodegeneration, while the motor and neuromuscular phenotypes seemed neurodegenerative, underlined by a progressive loss of upper and lower motor neurons as well as distal denervation. This is accompanied by progressive elevated TDP-43 protein and mRNA levels in cortex and spinal cord of homozygous mutant mice from 3 months of age, together with increased cytoplasmic TDP-43 mislocalisation in cortex, hippocampus, hypothalamus, and spinal cord at 12 months of age. In conclusion, we find that Tardbp M323K homozygous mutant mice model many aspects of human TDP-43 proteinopathies, evidencing a dual role for TDP-43 in brain morphogenesis as well as in the maintenance of the motor system, making them an ideal in vivo model system to study the complex biology of TDP-43.

Noninvasive and Multiplex Self-Test of Kidney Disease Biomarkers with Graphene-Based Lab-on-a-Chip (G-LOC): Toward Digital Diagnostics in the Hands of Patients.

Chronic kidney disease is one of the major health issues worldwide. However, diagnosis is now highly centralized in large laboratories, resulting in low access to patient monitoring and poor personalized treatments. This work reports the development of a graphene-based lab-on-a-chip (G-LOC) for the digital testing of renal function biomarkers in serum and saliva samples. G-LOC integrates multiple bioelectronic sensors with a microfluidic system that enables multiplex self-testing of urea, potassium, sodium, and chloride. The linearity, limit of detection (LOD), accuracy, and coefficient of variability (CV) were studied. Accuracy values higher than 95.5% and CV lower than 9% were obtained for all of the biomarkers. The analytical performance was compared against three reference lab benchtop analyzers by measuring healthy- and renal-failure-level samples of serum. From receiver operating characteristic (ROC) plots, sensitivities (%) of 99.7, 97.6, 99.1, and 89.0 were obtained for urea, potassium, sodium, and chloride, respectively. Then, the test was evaluated in noninvasive saliva samples and compared against reference methods. Correlation and Bland-Altman plots showed good correlation and agreement of the G-LOC with the reference methods. It is noteworthy that the precision of G-LOC was similar to better than benchtop lab analyzers, with the advantage of being highly portable. Finally, a user testing study was conducted. The analytical performance obtained with untrained volunteers was similar to that obtained with trained chemists. Additionally, based on a user experience survey, G-LOC was found to have very simple usability and would be suitable for at-home diagnostics.

Systemic Arterial Oxygen Levels Differentiate Pre- and Post-capillary Predominant Hemodynamic Abnormalities During Exercise in Undifferentiated Dyspnea on Exertion.

BACKGROUND: Whether systemic oxygen levels (SaO2) during exercise can provide a window into invasively derived exercise hemodynamic profiles in patients with undifferentiated dyspnea on exertion is unknown. METHODS: We performed cardiopulmonary exercise testing with invasive hemodynamic monitoring and arterial blood gas sampling in individuals referred for dyspnea on exertion. Receiver operator analysis was performed to distinguish heart failure with preserved ejection fraction from pulmonary arterial hypertension. RESULTS: Among 253 patients (mean ± SD, age 63 ± 14 years, 55% female, arterial O2 [PaO2] 87 ± 14 mmHg, SaO2 96% ± 4%, resting pulmonary capillary wedge pressure [PCWP] 18 ± 4mmHg, and pulmonary vascular resistance [PVR] 2.7 ± 1.2 Wood units), there was no exercise PCWP threshold, measured up to 49 mmHg, above which hypoxemia was consistently observed. Exercise PaO2 was not correlated with exercise PCWP (rho = 0.04; P = 0.51) but did relate to exercise PVR (rho = -0.46; P < 0.001). Exercise PaO2 and SaO2 levels distinguished left-heart-predominant dysfunction from pulmonary-vascular-predominant dysfunction with an area under the curve of 0.89 and 0.89, respectively. CONCLUSION: Systemic O2 levels during exercise distinguish relative pre- and post-capillary pulmonary hemodynamic abnormalities in patients with undifferentiated dyspnea. Hypoxemia during upright exercise should not be attributed to isolated elevation in left heart filling pressures and should prompt consideration of pulmonary vascular dysfunction.

An urgent call to address work-related psychosocial hazards and improve worker well-being.

Work-related psychosocial hazards are on the verge of surpassing many other occupational hazards in their contribution to ill-health, injury, disability, direct and indirect costs, and impact on business and national productivity. The risks associated with exposure to psychosocial hazards at work are compounded by the increasing background prevalence of mental health disorders in the working-age population. The extensive and cumulative impacts of these exposures represent an alarming public health problem that merits immediate, increased attention. In this paper, we review the linkage between work-related psychosocial hazards and adverse effects, their economic burden, and interventions to prevent and control these hazards. We identify six crucial societal actions: (1) increase awareness of this critical issue through a comprehensive public campaign; (2) increase etiologic, intervention, and implementation research; (3) initiate or augment surveillance efforts; (4) increase translation of research findings into guidance for employers and workers; (5) increase the number and diversity of professionals skilled in preventing and addressing psychosocial hazards; and (6) develop a national regulatory or consensus standard to prevent and control work-related psychosocial hazards.

Vital Signs: Health Worker-Perceived Working Conditions and Symptoms of Poor Mental Health - Quality of Worklife Survey, United States, 2018-2022.

Introduction: Health workers faced overwhelming demands and experienced crisis levels of burnout before the COVID-19 pandemic; the pandemic presented unique challenges that further impaired their mental health. Methods: Data from the General Social Survey Quality of Worklife Module were analyzed to compare self-reported mental health symptoms among U.S. adult workers from 2018 (1,443 respondents, including 226 health workers) and 2022 (1,952, including 325 health workers). Logistic regression was used to examine associations between health workers' reported perceptions of working conditions and anxiety, depression, and burnout. Results: From 2018 to 2022, health workers reported an increase of 1.2 days of poor mental health during the previous 30 days (from 3.3 days to 4.5 days); the percentage who reported feeling burnout very often (11.6% to 19.0%) increased. In 2022, health workers experienced a decrease in odds of burnout if they trusted management (odds ratio [OR] = 0.40), had supervisor help (OR = 0.26), had enough time to complete work (OR = 0.33), and felt that their workplace supported productivity (OR = 0.38), compared with those who did not. Harassment at work was associated with increased odds of anxiety (OR = 5.01), depression (OR = 3.38), and burnout (OR = 5.83). Conclusions and implications for public health practice: Health workers continued to face a mental health crisis in 2022. Positive working conditions were associated with less burnout and better mental health. CDC's National Institute for Occupational Safety and Health has developed a national campaign, Impact Wellbeing, to provide employers of health workers with resources to improve the mental health of these workers.

Reimagining Thriving Ethics Programs without Ethics Committees.

With the increasing professionalization of clinical ethics, some hospitals and health systems utilize both ethics committees and professional clinical ethicists to address their ethics needs. Drawing upon historical critiques of ethics committees and their own experiences, the authors argue that, in ethics programs with one or more professional clinical ethicists, ethics committees should be dissolved when they fail to meet minimum standards of effectiveness. The authors outline several criteria for assessing effectiveness, describe the benefits of a model that places primary responsibility for ethics work with professional clinical ethicists-the PCE-primary model, and offer suggestions for alternative ethics program structures that empower healthcare professionals to contribute to ethics work in ways more tailored to their strengths and skills while minimizing the shortcomings of ethics committees.

A staffing perspective on barriers to and facilitators of temporary worker safety and health.

BACKGROUND: Research has documented occupational health disparities, including higher rates of work-related injuries, among temporary workers compared with workers in standard employment arrangements. According to guidance from the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH), both staffing companies and host employers are responsible for protecting the occupational safety and health (OSH) of temporary workers. To date, there has been little qualitative research on temporary worker OSH in the United States and a lack of evidence-based OSH programs designed to meet the needs of temporary workers. The aim of this study was to better understand the barriers to and facilitators of temporary worker OSH from the perspective of US staffing companies. METHODS: In-depth interviews were conducted with a convenience sample of representatives from 15 US staffing companies. Interviews were audio recorded, transcribed verbatim, and analyzed through a three-step process. RESULTS: Commonly mentioned barriers to temporary worker OSH include differential treatment of temporary workers by host employers; lack of understanding among host employers and staffing companies of joint OSH responsibilities; and workers' fear of job loss or other negative repercussions if they report an injury or illness or voice OSH concerns. Commonly mentioned facilitators of temporary worker OSH include conducting client assessments and site visits and fostering strong communication and relationships with both host employers and temporary workers. CONCLUSIONS: These findings can help inform the tailoring of OSH programs to promote health equity in temporary workers.

Sizing, stabilising, and cloning repeat-expansions for gene targeting constructs.

Aberrant microsatellite repeat-expansions at specific loci within the human genome cause several distinct, heritable, and predominantly neurological, disorders. Creating models for these diseases poses a challenge, due to the instability of such repeats in bacterial vectors, especially with large repeat expansions. Designing constructs for more precise genome engineering projects, such as engineering knock-in mice, proves a greater challenge still, since these unstable repeats require numerous cloning steps in order to introduce homology arms or selection cassettes. Here, we report our efforts to clone a large hexanucleotide repeat in the C9orf72 gene, originating from within a BAC construct, derived from a C9orf72-ALS patient. We provide detailed methods for efficient repeat sizing and growth conditions in bacteria to facilitate repeat retention during growth and sub-culturing. We report that sub-cloning into a linear vector dramatically improves stability, but is dependent on the relative orientation of DNA replication through the repeat, consistent with previous studies. We envisage the findings presented here provide a relatively straightforward route to maintaining large-range microsatellite repeat-expansions, for efficient cloning into vectors.

An evolutionarily conserved long noncoding RNA TUNA controls pluripotency and neural lineage commitment.

Here, we generated a genome-scale shRNA library targeting long intergenic noncoding RNAs (lincRNAs) in the mouse. We performed an unbiased loss-of-function study in mouse embryonic stem cells (mESCs) and identified 20 lincRNAs involved in the maintenance of pluripotency. Among these, TUNA (Tcl1 Upstream Neuron-Associated lincRNA, or megamind) was required for pluripotency and formed a complex with three RNA-binding proteins (RBPs). The TUNA-RBP complex was detected at the promoters of Nanog, Sox2, and Fgf4, and knockdown of TUNA or the individual RBPs inhibited neural differentiation of mESCs. TUNA showed striking evolutionary conservation of both sequence- and CNS-restricted expression in vertebrates. Accordingly, knockdown of tuna in zebrafish caused impaired locomotor function, and TUNA expression in the brains of Huntington's disease patients was significantly associated with disease grade. Our results suggest that the lincRNA TUNA plays a vital role in pluripotency and neural differentiation of ESCs and is associated with neurological function of adult vertebrates.

Work-related fatigue: A hazard for workers experiencing disproportionate occupational risks.

BACKGROUND: Long working hours and fatigue are significant occupational safety and health (OSH) hazards for working populations who experience disproportionate risks of injury and illness. These groups include young or new workers, aging workers, contingent and temporary workers, immigrant and nonnative workers, female workers, minority workers, workers with low levels of education and lower socioeconomic status, and small business employees. An increasing focus on newer determinants of health in the workplace, such as health equity and work-life conflict, in worker populations at greater risk for injury or illness, provides an opportunity for researchers to address the causes and consequences of work-related fatigue in high-risk populations. METHODS: Articles in the OSH literature that addressed fatigue in higher-risk workers were identified by the authors or recommended by subject matter experts in workplace fatigue as part of a Working Hours, Sleep and Fatigue Forum. Additional articles were identified by searching for a combination of specific at-risk worker group titles (e.g., female workers, temporary workers) with fatigue or working hours. RESULTS: There remains a paucity of research specifically addressing working hours and fatigue among disproportionately at-risk worker populations. The literature reviewed in this paper suggests that several of these populations are at increased risk of fatigue due to multiple factors, such as irregular shifts, lack of access to fatigue management resources, and socioeconomic barriers. CONCLUSIONS: More research is needed to identify solutions to address fatigue in working populations who may be at greater risk for its consequences by virtue of adverse socioeconomic and related factors. Interventions to address work-related fatigue in specific at-risk worker groups should also consider the multiple and overlapping categories of risk within these populations.

Becoming Inclusive: Actionable Steps to Diversify the Field of Clinical Ethics.

At the 2022 Clinical Ethics Unconference, the authors perceived a significant lack of racial and ethnic diversity, which was consistent with their experiences in other clinical ethics settings. As a result, they convened a working group to address the pervasive lack of diversity present in the field of clinical ethics and to propose strategies to increase the representation of people from racial and ethnic minority populations. This article identifies the harms associated with the lack of diversity in the healthcare setting and translates these to the field of clinical ethics. The article then proposes a framework that may be used to help diversify the field of clinical ethics. Specifically, the authors identify existing barriers to appropriate diversity, actionable steps to increase diversity, and tools the field can utilize to systematically assess its progress with respect to achieving diversity.

A novel knockout mouse for the small EDRK-rich factor 2 (Serf2) showing developmental and other deficits.

The small EDRK-rich factor 2 (SERF2) is a highly conserved protein that modifies amyloid fibre assembly in vitro and promotes protein misfolding. However, the role of SERF2 in regulating age-related proteotoxicity remains largely unexplored due to a lack of in vivo models. Here, we report the generation of Serf2 knockout mice using an ES cell targeting approach, with Serf2 knockout alleles being bred onto different defined genetic backgrounds. We highlight phenotyping data from heterozygous Serf2+/- mice, including unexpected male-specific phenotypes in startle response and pre-pulse inhibition. We report embryonic lethality in Serf2-/- null animals when bred onto a C57BL/6 N background. However, homozygous null animals were viable on a mixed genetic background and, remarkably, developed without obvious abnormalities. The Serf2 knockout mice provide a powerful tool to further investigate the role of SERF2 protein in previously unexplored pathophysiological pathways in the context of a whole organism.

Differential Clinical Profiles, Exercise Responses, and Outcomes Associated With Existing HFpEF Definitions.

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) is common, yet there is currently no consensus on how to define HFpEF according to various society and clinical trial criteria. How clinical and hemodynamic profiles of patients vary across definitions is unclear. We sought to determine clinical characteristics, as well as physiologic and prognostic implications of applying various criteria to define HFpEF. METHODS: We examined consecutive patients with chronic exertional dyspnea (New York Heart Association class II to IV) and ejection fraction ≥50% referred for comprehensive cardiopulmonary exercise testing with invasive hemodynamic monitoring. We applied societal and clinical trial HFpEF definitions and compared clinical profiles, exercise responses, and cardiovascular outcomes. RESULTS: Of 461 patients (age 58±15 years, 62% women), 416 met American College of Cardiology/American Heart Association (ACC/AHA), 205 met European Society of Cardiology (ESC), and 55 met Heart Failure Society of America (HFSA) criteria for HFpEF. Clinical profiles and exercise capacity varied across definitions, with peak oxygen uptake of 16.2±5.2 (ACC/AHA), 14.1±4.2 (ESC), and 12.7±3.1 mL·kg-1·min-1 (HFSA). A total of 243 patients had hemodynamic evidence of HFpEF (abnormal rest or exercise filling pressures), of whom 222 met ACC/AHA, 161 met ESC, and 41 met HFSA criteria. Over a mean follow-up of 3.8 years, the incidence of cardiovascular outcomes ranged from 75 (ACC/AHA) to 298 events per 1000 person-years (HFSA). Application of clinical trial definitions of HFpEF similarly resulted in distinct patient classification and prognostication. CONCLUSIONS: Use of different HFpEF classifications variably enriches for future cardiovascular events, but at the expense of not including up to 85% of individuals with physiologic evidence of HFpEF. Comprehensive phenotyping of patients with suspected heart failure highlights the limitations and heterogeneity of current HFpEF definitions and may help to refine HFpEF subgrouping to test therapeutic interventions.

Whole-genome microRNA screening identifies let-7 and mir-18 as regulators of germ layer formation during early embryogenesis.

Tight control over the segregation of endoderm, mesoderm, and ectoderm is essential for normal embryonic development of all species, yet how neighboring embryonic blastomeres can contribute to different germ layers has never been fully explained. We postulated that microRNAs, which fine-tune many biological processes, might modulate the response of embryonic blastomeres to growth factors and other signals that govern germ layer fate. A systematic screen of a whole-genome microRNA library revealed that the let-7 and miR-18 families increase mesoderm at the expense of endoderm in mouse embryonic stem cells. Both families are expressed in ectoderm and mesoderm, but not endoderm, as these tissues become distinct during mouse and frog embryogenesis. Blocking let-7 function in vivo dramatically affected cell fate, diverting presumptive mesoderm and ectoderm into endoderm. siRNA knockdown of computationally predicted targets followed by mutational analyses revealed that let-7 and miR-18 down-regulate Acvr1b and Smad2, respectively, to attenuate Nodal responsiveness and bias blastomeres to ectoderm and mesoderm fates. These findings suggest a crucial role for the let-7 and miR-18 families in germ layer specification and reveal a remarkable conservation of function from amphibians to mammals.

How Much Volume Should Healthcare Ethics Consult Services Have?

BACKGROUND: No standard method exists to assess how many consults a healthcare ethics consultation (HCEC) service should perform. To address this, we developed a method to estimate the volume of HCEC services based on a mixed-methods approach that included a systematic review and survey data on the volume of consult services requested. METHODS: Our investigation included a systematic review of studies that reported the volume of HCEC services that were requested from 2000 to 2017, institutional surveys, and statistical analyses that estimated the volume of HCEC services that were adjusted to the size of the hospitals in the survey and to population acuity. RESULTS: We contacted the authors of 19 studies that met our inclusion criteria; 17 authors responded to the institutional survey and five provided annualized data points. We found that standard methods of reporting the volume of HCEC services led to inaccuracies in estimating the growth of HCEC services over time. To rectify this, we proposed two means to estimate volume based on either the service goals of HCEC services or hospital size and acuity. DISCUSSION: The statistical limitations of our study highlight the need to standardize the sharing and reporting of data in clinical ethics. Future work should further standardize methods of HCEC quality assessment using measures similar to those we describe.

Mouse but not zebrafish requires retinoic acid for control of neuromesodermal progenitors and body axis extension.

In mouse, retinoic acid (RA) is required for the early phase of body axis extension controlled by a population of neuromesodermal progenitors (NMPs) in the trunk called expanding-NMPs, but not for the later phase of body axis extension controlled by a population of NMPs in the tail called depleting-NMPs. Recent observations suggest that zebrafish utilize depleting-NMPs but not expanding-NMPs for body axis extension. In zebrafish, a role for RA in body axis extension was not supported by previous studies on aldh1a2 (raldh2) mutants lacking RA synthesis. Here, by treating zebrafish embryos with an RA synthesis inhibitor, we also found that body axis extension and somitogenesis was not perturbed, although loss of pectoral fin and cardiac edema were observed consistent with previous studies. The conclusion that zebrafish diverges from mouse in not requiring RA for body axis extension is consistent with zebrafish lacking early expanding-NMPs to generate the trunk. We suggest that RA control of body axis extension was added to higher vertebrates during evolution of expanding-NMPs.