Selective Cdk9 inhibition resolves neutrophilic inflammation and enhances cardiac regeneration in larval zebrafish.

Sustained neutrophilic inflammation is detrimental for cardiac repair and associated with adverse outcomes following myocardial infarction (MI). An attractive therapeutic strategy to treat MI is to reduce or remove infiltrating neutrophils to promote downstream reparative mechanisms. CDK9 inhibitor compounds enhance the resolution of neutrophilic inflammation; however, their effects on cardiac repair/regeneration are unknown. We have devised a cardiac injury model to investigate inflammatory and regenerative responses in larval zebrafish using heartbeat-synchronised light-sheet fluorescence microscopy. We used this model to test two clinically approved CDK9 inhibitors, AT7519 and flavopiridol, examining their effects on neutrophils, macrophages and cardiomyocyte regeneration. We found that AT7519 and flavopiridol resolve neutrophil infiltration by inducing reverse migration from the cardiac lesion. Although continuous exposure to AT7519 or flavopiridol caused adverse phenotypes, transient treatment accelerated neutrophil resolution while avoiding these effects. Transient treatment with AT7519, but not flavopiridol, augmented wound-associated macrophage polarisation, which enhanced macrophage-dependent cardiomyocyte number expansion and the rate of myocardial wound closure. Using cdk9-/- knockout mutants, we showed that AT7519 is a selective CDK9 inhibitor, revealing the potential of such treatments to promote cardiac repair/regeneration.

Fli1+ cells transcriptional analysis reveals an Lmo2-Prdm16 axis in angiogenesis.

A network of molecular factors drives the development, differentiation, and maintenance of endothelial cells. Friend leukemia integration 1 transcription factor (FLI1) is a bona fide marker of endothelial cells during early development. In zebrafish Tg(fli1:EGFP)y1 , we identified two endothelial cell populations, high-fli1+ and low-fli1+, by the intensity of green fluorescent protein signal. By comparing RNA-sequencing analysis of non-fli1 expressing cells (fli1-) with these two (fli1+) cell populations, we identified several up-regulated genes, not previously recognized as important, during endothelial development. Compared with fli1- and low-fli1+ cells, high-fli1+ cells showed up-regulated expression of the zinc finger transcription factor PRDI-BF1 and RIZ homology domain containing 16 (prdm16). Prdm16 knockdown (KD) by morpholino in the zebrafish larva was associated with impaired angiogenesis and increased number of low-fli1+ cells at the expense of high-fli1+ cells. In addition, PRDM16 KD in endothelial cells derived from human-induced pluripotent stem cells impaired their differentiation and migration in vitro. Moreover, zebrafish mutants (mut) with loss of function for the oncogene LIM domain only 2 (lmo2) also showed reduced prdm16 gene expression combined with impaired angiogenesis. Prdm16 expression was reduced further in endothelial (CD31+) cells compared with CD31- cells isolated from lmo2-mutants (lmo2-mut) embryos. Chromatin immunoprecipitation-PCR demonstrated that Lmo2 binds to the promoter and directly regulates the transcription of prdm16 This work unveils a mechanism by which prdm16 expression is activated in endothelial cells by Lmo2 and highlights a possible therapeutic pathway by which to modulate endothelial cell growth and repair.

Corticosteroid Receptors in Cardiac Health and Disease.

Nuclear receptors play a central role in both energy metabolism and cardiomyocyte death and survival in the heart. Recent evidence suggests they may also influence cardiomyocyte endowment. Although several members of the nuclear receptor family play key roles in heart maturation (including thyroid hormone receptors) and cardiac metabolism, here, the focus will be on the corticosteroid receptors, the glucocorticoid receptor (GR) and mineralocorticoid receptor (MR). The heart is an important target for the actions of corticosteroids, yet the homeostatic role of GR and MR in the healthy heart has been elusive. However, MR antagonists are important in the treatment of heart failure, a condition associated with mitochondrial dysfunction and energy failure in cardiomyocytes leading to mitochondria-initiated cardiomyocyte death (Ingwall and Weiss, Circ Res 95:135-145, 2014; Ingwall , Cardiovasc Res 81:412-419, 2009; Zhou and Tian , J Clin Invest 128:3716-3726, 2018). In contrast, animal studies suggest GR activation in cardiomyocytes has a cardioprotective role, including in heart failure.

Predicting readmission and death after hospital discharge: a comparison of conventional frailty measurement with an electronic health record-based score.

BACKGROUND: frailty measurement may identify patients at risk of decline after hospital discharge, but many measures require specialist review and/or additional testing. OBJECTIVE: to compare validated frailty tools with routine electronic health record (EHR) data at hospital discharge, for associations with readmission or death. DESIGN: observational cohort study. SETTING: hospital ward. SUBJECTS: consented cardiology inpatients ≥70 years old within 24 hours of discharge. METHODS: patients underwent Fried, Short Physical Performance Battery (SPPB), PRISMA-7 and Clinical Frailty Scale (CFS) assessments. An EHR risk score was derived from the proportion of 31 possible frailty markers present. Electronic follow-up was completed for a primary outcome of 90-day readmission or death. Secondary outcomes were mortality and days alive at home ('home time') at 12 months. RESULTS: in total, 186 patients were included (79 ± 6 years old, 64% males). The primary outcome occurred in 55 (30%) patients. Fried (hazard ratio [HR] 1.47 per standard deviation [SD] increase, 95% confidence interval [CI] 1.18-1.81, P < 0.001), CFS (HR 1.24 per SD increase, 95% CI 1.01-1.51, P = 0.04) and EHR risk scores (HR 1.35 per SD increase, 95% CI 1.02-1.78, P = 0.04) were independently associated with the primary outcome after adjustment for age, sex and co-morbidity, but the SPPB and PRISMA-7 were not. The EHR risk score was independently associated with mortality and home time at 12 months. CONCLUSIONS: frailty measurement at hospital discharge identifies patients at risk of poorer outcomes. An EHR-based risk score appeared equivalent to validated frailty tools and may be automated to screen patients at scale, but this requires further validation.

Adjudication of cardiovascular events in patients with chronic obstructive pulmonary disease: SUMMIT trial.

BACKGROUND: Adjudicated cause-specific mortality has been used in major trials of chronic obstructive pulmonary disease. However, there is less experience with adjudicated major adverse cardiovascular events as a key efficacy outcome in chronic obstructive pulmonary disease trials. The Study to Understand Mortality and Morbidity in chronic obstructive pulmonary disease trial required a Clinical Endpoint Committee to adjudicate the outcomes of modified major adverse cardiovascular events and cause-specific mortality. METHODS AND RESULTS: A six-member Clinical Endpoint Committee reviewed adverse event and serious adverse event reports included in a list of 204 Medical Dictionary for Regulatory Activities terms. Adverse events were triaged by one Clinical Endpoint Committee member, and then reviewed by three reviewers (round 1). If these three disagreed on the adjudication, the event was discussed by the full committee to reach a consensus (round 2). Among 16,485 participants, 48,105 adverse events were reported, among which 3314 were reviewed by the Clinical Endpoint Committee. After triage, 1827 were adjudicated in round 1; 338 required committee consensus in round 2, yielding 450 myocardial infarctions, strokes, unstable anginas or transient ischaemic attacks. Only 20/1627 (1%) non-serious adverse events were adjudicated as cardiovascular events. Only 45/204 Medical Dictionary for Regulatory Activities terms reviewed yielded cardiovascular events. A total of 430 deaths were adjudicated in round 1 and 631 in round 2, yielding 459 cardiovascular deaths. Adjudication of chest pain and sudden death often required additional information from site investigators. Site assessment of cardiovascular death was moderately specific (501/602 = 83%) but not sensitive (256/459 = 56%). CONCLUSION: A Clinical Endpoint Committee is useful for adjudication of major adverse cardiovascular events in chronic obstructive pulmonary disease trials but requires considerable resources and effort by investigators. This process can be streamlined by reviewing only serious adverse events and filtering by selected Medical Dictionary for Regulatory Activities terms.

Frailty assessment and risk prediction by GRACE score in older patients with acute myocardial infarction.

BACKGROUND: Risk prediction after myocardial infarction is often complex in older patients. The Global Registry of Acute Coronary Events (GRACE) model includes clinical parameters and age, but not frailty. We hypothesised that frailty would enhance the prognostic properties of GRACE. METHODS: We performed a prospective observational cohort study in two independent cardiology units: the Royal Infirmary of Edinburgh, UK (primary cohort) and the South Yorkshire Cardiothoracic Centre, Sheffield, UK (external validation). The study sample included 198 patients ≥65 years old hospitalised with type 1 myocardial infarction (primary cohort) and 96 patients ≥65 years old undergoing cardiac catheterisation for myocardial infarction (external validation). Frailty was assessed using the Clinical Frailty Scale (CFS). The GRACE 2.0 estimated risk of 12-month mortality, Charlson comorbidity index and Karnofsky disability scale were also determined for each patient. RESULTS: Forty (20%) patients were frail (CFS ≥5). These individuals had greater comorbidity, functional impairment and a higher risk of death at 12 months (49% vs. 9% in non-frail patients, p < 0.001). The hazard of 12-month all-cause mortality nearly doubled per point increase in CFS after adjustment for age, sex and comorbidity (Hazard Ratio [HR] 1.90, 95% CI 1.47-2.44, p < 0.001). The CFS had good discrimination for mortality by Receiver Operating Characteristic (ROC) curve analysis (Area Under the Curve [AUC] 0.81, 95% CI 0.72-0.89) and enhanced the GRACE estimate (AUC 0.86 vs. 0.80 without CFS, p = 0.04). At existing GRACE thresholds, the CFS resulted in a Net Reclassification Improvement (NRI) of 0.44 (95% CI 0.28-0.60, p < 0.001), largely through reductions in risk estimates amongst non-frail patients. Similar findings were observed in the external validation cohort (NRI 0.46, 95% CI 0.23-0.69, p < 0.001). CONCLUSIONS: The GRACE score overestimated mortality risk after myocardial infarction in these cohorts of older patients. The CFS is a simple guided frailty tool that may enhance prediction in this setting. These findings merit evaluation in larger cohorts of unselected patients. TRIAL REGISTRATION: Clinicaltrials.gov; NCT02302014 (November 26th 2014, retrospectively registered).

Cardiomyocyte proliferation in zebrafish and mammals: lessons for human disease.

Cardiomyocytes proliferate profusely during early development and for a brief period after birth in mammals. Within a month after birth, this proliferative capability is dramatically reduced in mammals unlike lower vertebrates where it persists into adult life. The zebrafish, for example, retains the ability to regenerate the apex of the heart following resection by a mechanism predominantly driven by cardiomyocyte proliferation. Differences in proliferative capacity of cardiomyocytes in adulthood between mammals and lower vertebrates are closely liked to ontogenetic or phylogenetic factors. Elucidation of these factors has the potential to provide enormous benefits if they lead to the development of therapeutic strategies that facilitate cardiomyocyte proliferation. In this review, we highlight the differences between Mammalian and Zebrafish cardiomyocytes, which could explain at least in part the different proliferative capacities in these two species. We discuss the advantages of the zebrafish as a model of cardiomyocyte proliferation, particularly at the embryonic stage. We also identify a number of key molecular pathways with potential to reveal key steps in switching cardiomyocytes from a quiescent to a proliferative phenotype.

CDK9 and its repressor LARP7 modulate cardiomyocyte proliferation and response to injury in the zebrafish heart.

Cyclin dependent kinase (Cdk)9 acts through the positive transcription elongation factor-b (P-TEFb) complex to activate and expand transcription through RNA polymerase II. It has also been shown to regulate cardiomyocyte hypertrophy, with recent evidence linking it to cardiomyocyte proliferation. We hypothesised that modification of CDK9 activity could both impair and enhance the cardiac response to injury by modifying cardiomyocyte proliferation. Cdk9 expression and activity were inhibited in the zebrafish (Danio rerio) embryo. We show that dephosphorylation of residue Ser2 on the C-terminal domain of RNA polymerase II is associated with impaired cardiac structure and function, and cardiomyocyte proliferation and also results in impaired functional recovery following cardiac laser injury. In contrast, de-repression of Cdk9 activity, through knockdown of La-related protein (Larp7) increases phosphorylation of Ser2 in RNA polymerase II and increases cardiomyocyte proliferation. Larp7 knockdown rescued the structural and functional phenotype associated with knockdown of Cdk9. The balance of Cdk9 and Larp7 plays a key role in cardiomyocyte proliferation and response to injury. Larp7 represents a potentially novel therapeutic target to promote cardiomyocyte proliferation and recovery from injury.

Temporal cohesion of the structural, functional and molecular characteristics of the developing zebrafish heart.

Heart formation is a complex, dynamic and highly coordinated process of molecular, morphogenetic and functional factors with each interacting and contributing to formation of the mature organ. Cardiac abnormalities in early life can be lethal in mammals but not in the zebrafish embryo which has been widely used to study the developing heart. While early cardiac development in the zebrafish has been well characterized, functional changes during development and how these relate to architectural, cellular and molecular aspects of development have not been well described previously. To address this we have carefully characterised cardiac structure, function, cardiomyocyte proliferation and cardiac-specific gene expression between 48 and 120 hpf in the zebrafish. We show that the zebrafish heart increases in volume and changes shape significantly between 48 and 72 hpf accompanied by a 40% increase in cardiomyocyte number. Between 96 and 120 hpf, while external heart expansion slows, there is rapid formation of a mature and extensive trabecular network within the ventricle chamber. While ejection fraction does not change during the course of development other determinants of contractile function increase significantly particularly between 72 and 96 hpf leading to an increase in cardinal vein blood flow. This study has revealed a number of novel aspects of cardiac developmental dynamics with striking temporal orchestration of structure and function within the first few days of development. These changes are associated with changes in expression of developmental and maturational genes. This study provides important insights into the complex temporal relationship between structure and function of the developing zebrafish heart.

Systematic hand-held echocardiography in patients hospitalised with acute coronary syndrome.

AIMS: Transthoracic echocardiography is recommended in all patients with acute coronary syndrome but is time-consuming and lacks an evidence base. We aimed to assess the feasibility, diagnostic accuracy and time-efficiency of hand-held echocardiography in patients with acute coronary syndrome and describe the impact of echocardiography on clinical management in this setting. METHODS AND RESULTS: Patients with acute coronary syndrome underwent both hand-held and transthoracic echocardiography with agreement between key imaging parameters assessed using kappa statistics. The immediate clinical impact of hand-held echocardiography in this population was systematically evaluated.Overall, 262 patients (65±12 years, 71% male) participated. Agreement between hand-held and transthoracic echocardiography was good-to-excellent (kappa 0.60-1.00) with hand-held echocardiography having an overall negative predictive value of 95%. Hand-held echocardiography was performed rapidly (7.7±1.6 min) and completed a median of 5 [interquartile range 3-20] hours earlier than transthoracic echocardiography. Systematic hand-held echocardiography in all patients with acute coronary syndrome identified an important cardiac abnormality in 50% and the clinical management plan was changed by echocardiography in 42%. In 85% of cases, hand-held echocardiography was sufficient for patient decision-making and transthoracic echocardiography was no longer deemed necessary. CONCLUSIONS: In patients with acute coronary syndrome, hand-held echocardiography provides comparable results to transthoracic echocardiography, can be more rapidly applied and gives sufficient imaging information for decision-making in the vast majority of patients. Systematic echocardiography has clinical impact in half of patients, supporting the clinical utility of echocardiography in this population, and providing an evidence-base for current guidelines.

Isolation of Cardiac Endothelial Cells for Transcriptomic Analysis of the Zebrafish and Mouse Heart.

Isolation of high quality cardiac endothelial cells is a prerequisite for successful bulk and single cell sequencing for RNA (scRNA-seq). We describe a protocol using both enzymatic and mechanical dissociation and fluorescence-activated cell sorting (FACS) to isolate endothelial cells from larval and adult zebrafish hearts and from healthy and ischemic adult mouse hearts. Endothelial cells with high viability and purity can be obtained using this method for downstream transcriptional analyses applications.

Criteria for Referral of Patients With Advanced Heart Failure for Specialized Palliative Care.

BACKGROUND: Patients with advanced heart failure have substantial supportive care needs. Specialist palliative care can be beneficial, but it is unclear who is most appropriate for referral and when patients should be referred. OBJECTIVES: We conducted a Delphi study of international experts to identify consensus referral criteria for specialist palliative care for patients with advanced heart failure. METHODS: Clinicians from 5 continents with expertise in the integration of cardiology and palliative care were asked to rate 34 disease-based, 24 needs-based, and 9 time-based criteria over 3 rounds. Consensus was defined a priori as ≥70% agreement. A criterion was coded as major if the experts endorsed that meeting that criterion alone was adequate to justify a referral. RESULTS: The response rate was 44 of 46 (96%), 41 of 46 (89%), and 43 of 46 (93%) in the first, second, and third rounds, respectively. Panelists reached consensus on 25 major criteria for specialist palliative care referral. The 25 major criteria were categorized under 6 topics, including "advanced/refractory heart failure, comorbidities, and complications" (eg, cardiac cachexia, cardiorenal syndrome) (n = 8), "advanced heart failure therapies" (eg, chronic inotropes, precardiac transplant) (n = 4), "hospital utilization" (eg, emergency room visits, hospitalization) (n = 2), "prognostic estimate" (n = 1), "symptom burden/distress" (eg, severe physical/emotional/spiritual distress) (n = 6), and "decision making/social support" (eg, goals-of-care discussions) (n = 4). The majority (68%) of major criteria had ≥90% agreement. CONCLUSIONS: International experts reached consensus on a large number of criteria for referral to specialist palliative care. With further validation, these criteria may be useful for standardizing palliative care access in the inpatient and/or outpatient settings.

Macrophages trigger cardiomyocyte proliferation by increasing epicardial vegfaa expression during larval zebrafish heart regeneration.

Cardiac injury leads to the loss of cardiomyocytes, which are rapidly replaced by the proliferation of the surviving cells in zebrafish, but not in mammals. In both the regenerative zebrafish and non-regenerative mammals, cardiac injury induces a sustained macrophage response. Macrophages are required for cardiomyocyte proliferation during zebrafish cardiac regeneration, but the mechanisms whereby macrophages facilitate this crucial process are fundamentally unknown. Using heartbeat-synchronized live imaging, RNA sequencing, and macrophage-null genotypes in the larval zebrafish cardiac injury model, we characterize macrophage function and reveal that these cells activate the epicardium, inducing cardiomyocyte proliferation. Mechanistically, macrophages are specifically recruited to the epicardial-myocardial niche, triggering the expansion of the epicardium, which upregulates vegfaa expression to induce cardiomyocyte proliferation. Our data suggest that epicardial Vegfaa augments a developmental cardiac growth pathway via increased endocardial notch signaling. The identification of this macrophage-dependent mechanism of cardiac regeneration highlights immunomodulation as a potential strategy for enhancing mammalian cardiac repair.

18F-Sodium Fluoride Positron Emission Tomography and Computed Tomography in Acute Aortic Syndrome.

BACKGROUND: Acute aortic syndrome is associated with aortic medial degeneration. 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) detects microscopic tissue calcification as a marker of disease activity. OBJECTIVES: In a proof-of-concept study, this investigation aimed to establish whether 18F-NaF PET combined with computed tomography (CT) angiography could identify aortic medial disease activity in patients with acute aortic syndrome. METHODS: Patients with aortic dissection or intramural hematomas and control subjects underwent 18F-NaF PET/CT angiography of the aorta. Aortic 18F-NaF uptake was measured at the most diseased segment, and the maximum value was corrected for background blood pool activity (maximum tissue-to-background ratio [TBRmax]). Radiotracer uptake was compared with change in aortic size and major adverse aortic events (aortic rupture, aorta-related death, or aortic repair) over 45 ± 13 months. RESULTS: Aortic 18F-NaF uptake co-localized with histologically defined regions of microcalcification and elastin disruption. Compared with control subjects, patients with acute aortic syndrome had increased 18F-NaF uptake (TBRmax: 1.36 ± 0.39 [n = 20] vs 2.02 ± 0.42 [n = 47] respectively; P < 0.001) with enhanced uptake at the site of intimal disruption (+27.5%; P < 0.001). 18F-NaF uptake in the false lumen was associated with aortic growth (+7.1 mm/year; P = 0.011), and uptake in the outer aortic wall was associated with major adverse aortic events (HR: 8.5 [95% CI: 1.4-50.4]; P = 0.019). CONCLUSIONS: In patients with acute aortic syndrome, 18F-NaF uptake was enhanced at sites of disease activity and was associated with aortic growth and clinical events. 18F-NaF PET/CT holds promise as a noninvasive marker of disease severity and future risk in patients with acute aortic syndrome. (18F Sodium Fluoride PET/CT in Acute Aortic Syndrome [FAASt]; NCT03647566).

Implementation of a sensitive troponin I assay and risk of recurrent myocardial infarction and death in patients with suspected acute coronary syndrome.

CONTEXT: Although troponin assays have become increasingly more sensitive, it is unclear whether further reductions in the threshold of detection for plasma troponin concentrations will improve clinical outcomes in patients with suspected acute coronary syndrome (ACS). OBJECTIVE: To determine whether lowering the diagnostic threshold for myocardial infarction (MI) with a sensitive troponin assay could improve clinical outcomes. DESIGN, SETTING, AND PATIENTS: All consecutive patients admitted with suspected ACS to the Royal Infirmary of Edinburgh, Edinburgh, Scotland, before (n = 1038; February 1-July 31, 2008, during the validation phase) and after (n = 1054; February 1-July 31, 2009, during the implementation phase) lowering the threshold of detection for myocardial necrosis from 0.20 to 0.05 ng/mL with a sensitive troponin I assay were stratified into 3 groups (<0.05 ng/mL, 0.05-0.19 ng/mL, and ≥0.20 ng/mL). During the validation phase, only concentrations above the original diagnostic threshold of 0.20 ng/mL were reported to clinicians. MAIN OUTCOME MEASURE: Event-free survival (recurrent MI and death) at 1 year in patients grouped by plasma troponin concentrations. RESULTS: Plasma troponin concentrations were less than 0.05 ng/mL in 1340 patients (64%), 0.05 to 0.19 ng/mL in 170 patients (8%), and 0.20 ng/mL or more in 582 patients (28%). During the validation phase, 39% of patients with plasma troponin concentrations of 0.05 to 0.19 ng/mL were dead or had recurrent MI at 1 year compared with 7% and 24% of those patients with troponin concentrations of less than 0.05 ng/mL (P < .001) or 0.20 ng/mL or more (P = .007), respectively. During the implementation phase, lowering the diagnostic threshold to 0.05 ng/mL was associated with a lower risk of death and recurrent MI (from 39% to 21%) in patients with troponin concentrations of 0.05 to 0.19 ng/mL (odds ratio, 0.42; 95% confidence interval, 0.24-0.84; P = .01). CONCLUSIONS: In patients with suspected ACS, implementation of a sensitive troponin assay increased the diagnosis of MI and identified patients at high risk of recurrent MI and death. Lowering the diagnostic threshold of plasma troponin was associated with major reductions in morbidity and mortality.

PET/CT Technology in Adult Zebrafish: A Pilot Study Toward Live Longitudinal Imaging.

Decades of research have confirmed the beneficial and advantageous use of zebrafish (Danio rerio) as a model of human disease in biomedical studies. Not only are 71% of human genes shared with the zebrafish many of these genes are linked to human diseases. Currently, numerous transgenic and mutant genetic zebrafish lines are now widely available for use in research. Furthermore, zebrafish are relatively inexpensive to maintain compared to rodents. However, a limiting factor to fully utilising adult zebrafish in research is not the fish but the technological imaging tools available. In order to increase the utilisation of adult zebrafish, which are not naturally transparent, requires new imaging approaches. Therefore, this feasibility study: (1) presents an innovative designed PET/CT adult zebrafish imaging platform, capable of maintaining normal aquatic physiology during scanning; (2) assesses the practical aspects of adult zebrafish imaging; and (3) set basic procedural guidelines for zebrafish imaging during a PET/CT acquisition. Methods: With computer aided design (CAD) software an imaging platform was developed for 3D printing. A 3D printed zebrafish model was created from a CT acquisition of a zebrafish using the CAD software. This model and subsequently euthanised zebrafish were imaged post-injection using different concentrations of the radiotracer [18F]FDG with CT contrast. Results: PET/CT imaging was successful, revealing levels as low as 0.01 MBq could be detected in the fish. In the zebrafish imaging post-injection distribution of the radiotracer was observed away from the injection site as well as tissue uptake. Potential preliminary husbandry and welfare guidelines for the fish during and after PET/CT imaging were determined. Conclusion: Using PET/CT for adult zebrafish imaging as a viable non-invasive technological tool is feasible. Adult zebrafish PET/CT imaging has the potential to be a key imaging technique offering the possibilities of enhanced biomedical understanding and new translational data sets.

Chest pain presentations to hospital during the COVID-19 lockdown: Lessons for public health media campaigns.

OBJECTIVE: Emergency Department (ED) attendances with chest pain reduced during the COVID-19 lockdown. We performed a service evaluation project in NHS Lothian to explore how and why the COVID-19 pandemic and public health advice had affected chest pain presentations and help-seeking behaviour at an individual patient level using a qualitative interview approach. METHODS: We carried out 28 semi-structured telephone interviews with a convenience sample of patients who presented with chest pain during lockdown and in patients with known coronary heart disease under the outpatient care of a cardiologist in April and May 2020. Interviews were audio recorded and voice files listened to while making detailed notes. Salient themes and issues were documented as verbatim extracts. Interviews were analysed thematically. RESULTS: Patient interviews revealed three main themes. 1) pandemic help-seeking behaviour; describing how participants made the decision to seek professional healthcare assessment. 2) COVID-19 exposure concerns; describing how the subthemes of perceived vulnerability, wishing to protect others and adding pressure to the health service shaped their decision making for an episode of acute chest pain. 3) hospital experience; describing the difference between the imagined and actual experience in hospital. CONCLUSIONS: Qualitative interviews revealed how the pandemic shaped help-seeking practices, how patients interpreted their personal vulnerability to the virus, and described patient experience of attending hospital for assessment during this time. As patient numbers presenting to hospital appeared to mirror public health messaging, dynamic monitoring of this messaging should evaluate public response to healthcare campaigns to ensure the net impact on health, pandemic and non-pandemic related, is optimised.

Cardiac Energetics Before, During, and After Anthracycline-Based Chemotherapy in Breast Cancer Patients Using 31P Magnetic Resonance Spectroscopy: A Pilot Study.

Purpose: To explore the utility of phosphorus magnetic resonance spectroscopy (31P MRS) in identifying anthracycline-induced cardiac toxicity in patients with breast cancer. Methods: Twenty patients with newly diagnosed breast cancer receiving anthracycline-based chemotherapy had cardiac magnetic resonance assessment of left ventricular ejection fraction (LVEF) and 31P MRS to determine myocardial Phosphocreatine/Adenosine Triphosphate Ratio (PCr/ATP) at three time points: pre-, mid-, and end-chemotherapy. Plasma high sensitivity cardiac troponin-I (cTn-I) tests and electrocardiograms were also performed at these same time points. Results: Phosphocreatine/Adenosine Triphosphate did not change significantly between pre- and mid-chemo (2.16 ± 0.46 vs. 2.00 ± 0.56, p = 0.80) and pre- and end-chemo (2.16 ± 0.46 vs. 2.17 ± 0.86, p = 0.99). Mean LVEF reduced significantly by 5.1% between pre- and end-chemo (61.4 ± 4.4 vs. 56.3 ± 8.1 %, p = 0.02). Change in PCr/ATP ratios from pre- to end-chemo correlated inversely with changes in LVEF over the same period (r = -0.65, p = 0.006). Plasma cTn-I increased progressively during chemotherapy from pre- to mid-chemo (1.35 ± 0.81 to 4.40 ± 2.64 ng/L; p = 0.01) and from mid- to end-chemo (4.40 ± 2.64 to 18.33 ± 13.23 ng/L; p = 0.001). Conclusions: In this small cohort pilot study, we did not observe a clear change in mean PCr/ATP values during chemotherapy despite evidence of increased plasma cardiac biomarkers and reduced LVEF. Future similar studies should be adequately powered to take account of patient drop-out and variable changes in PCr/ATP and could include T1 and T2 mapping.

Nuclear S-nitrosylation impacts tissue regeneration in zebrafish.

Despite the importance of nitric oxide signaling in multiple biological processes, its role in tissue regeneration remains largely unexplored. Here, we provide evidence that inducible nitric oxide synthase (iNos) translocates to the nucleus during zebrafish tailfin regeneration and is associated with alterations in the nuclear S-nitrosylated proteome. iNos inhibitors or nitric oxide scavengers reduce protein S-nitrosylation and impair tailfin regeneration. Liquid chromatography/tandem mass spectrometry reveals an increase of up to 11-fold in the number of S-nitrosylated proteins during regeneration. Among these, Kdm1a, a well-known epigenetic modifier, is S-nitrosylated on Cys334. This alters Kdm1a binding to the CoRest complex, thus impairing its H3K4 demethylase activity, which is a response specific to the endothelial compartment. Rescue experiments show S-nitrosylation is essential for tailfin regeneration, and we identify downstream endothelial targets of Kdm1a S-nitrosylation. In this work, we define S-nitrosylation as an essential post-translational modification in tissue regeneration.