Routine Antenatal Echocardiography in High-Prevalence Areas of Rheumatic Heart Disease: A WHO-Guideline Systematic Review.

Background: Rheumatic Heart Disease (RHD) is the most common cause of valvular heart disease worldwide. Undiagnosed or untreated RHD can complicate pregnancy and lead to poor maternal and fetal outcomes and is a significant factor in non-obstetric morbidity. Echocardiography has an emerging role in screening for RHD. We aimed to critically analyse the evidence on the use of echocardiography for screening pregnant women for RHD in high-prevalence areas. Methods: We searched MEDLINE and Embase to identify the relevant reports. Two independent reviewers assessed the reports against the eligibility criteria in a double-blind process. Results: The searches (date: 4 April 2023) identified 432 records for screening. Ten non-controlled observational studies were identified, five using portable or handheld echocardiography, comprising data from 23,166 women. Prevalence of RHD varied across the studies, ranging from 0.4 to 6.6% (I2, heterogeneity >90%). Other cardiac abnormalities (e.g., congenital heart disease and left ventricular systolic dysfunction) were also detected <1% to 2% of cases. Certainty of evidence was very low. Conclusion: Echocardiography as part of antenatal care in high-prevalence areas may detect RHD or other cardiac abnormalities in asymptomatic pregnant women, potentially reducing the rates of disease progression and adverse labor-associated outcomes. However, this evidence is affected by the low certainty of evidence, and lack of studies comparing echocardiography versus standard antenatal care. Prospective Registration: PROSPERO 2022 July 4; CRD42022344081 Available from: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=344081. Research question: 'In areas with a high prevalence of rheumatic heart disease, should handheld echocardiography be added to routine antenatal care?'

Vehicle Position Detection Based on Machine Learning Algorithms in Dynamic Wireless Charging.

Dynamic wireless charging (DWC) has emerged as a viable approach to mitigate range anxiety by ensuring continuous and uninterrupted charging for electric vehicles in motion. DWC systems rely on the length of the transmitter, which can be categorized into long-track transmitters and segmented coil arrays. The segmented coil array, favored for its heightened efficiency and reduced electromagnetic interference, stands out as the preferred option. However, in such DWC systems, the need arises to detect the vehicle's position, specifically to activate the transmitter coils aligned with the receiver pad and de-energize uncoupled transmitter coils. This paper introduces various machine learning algorithms for precise vehicle position determination, accommodating diverse ground clearances of electric vehicles and various speeds. Through testing eight different machine learning algorithms and comparing the results, the random forest algorithm emerged as superior, displaying the lowest error in predicting the actual position.

The ATM Ser49Cys Variant Effects ATM Function as a Regulator of Oncogene-Induced Senescence.

An apical component of the cell cycle checkpoint and DNA damage repair response is the ataxia-telangiectasia mutated (ATM) Ser/Thr protein kinase. A variant of ATM, Ser49Cys (rs1800054; minor allele frequency = 0.011), has been associated with an elevated risk of melanoma development; however, the functional consequence of this variant is not defined. ATM-dependent signalling in response to DNA damage has been assessed in a panel of patient-derived lymphoblastoid lines and primary human melanocytic cell strains heterozygous for the ATM Ser49Cys variant allele. The ATM Ser49Cys allele appears functional for acute p53-dependent signalling in response to DNA damage. Expression of the variant allele did reduce the efficacy of oncogene expression in inducing senescence. These findings demonstrate that the ATM 146C>G Ser49Cys allele has little discernible effect on the acute response to DNA damage but has reduced function observed in the chronic response to oncogene over-expression. Analysis of melanoma, naevus and skin colour genomics and GWAS analyses have demonstrated no association of this variant with any of these outcomes. The modest loss of function detected suggest that the variant may act as a modifier of other variants of ATM/p53-dependent signalling.

Prognostic Value of Late Gadolinium Enhancement Detected on Cardiac Magnetic Resonance in Cardiac Sarcoidosis.

BACKGROUND: Sarcoidosis is a complex multisystem inflammatory disorder, with approximately 5% of patients having overt cardiac involvement. Patients with cardiac sarcoidosis are at an increased risk of both ventricular arrhythmias and sudden cardiac death. Previous studies have shown that the presence of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) is associated with an increased risk of mortality and ventricular arrhythmias and may be useful in predicting prognosis. OBJECTIVES: This systematic review and meta-analysis assessed the value of LGE on CMR imaging in predicting prognosis for patients with known or suspected cardiac sarcoidosis. METHODS: The authors searched the Embase and MEDLINE databases from inception to March 2022 for studies reporting individuals with known or suspected cardiac sarcoidosis referred for CMR with LGE. Outcomes were defined as all-cause mortality, ventricular arrhythmia, or a composite outcome of either death or ventricular arrhythmias. The primary analysis evaluated these outcomes according to the presence of LGE. A secondary analysis evaluated outcomes specifically according to the presence of biventricular LGE. RESULTS: Thirteen studies were included (1,318 participants) in the analysis, with an average participant age of 52.0 years and LGE prevalence of 13% to 70% over a follow-up of 3.1 years. Patients with LGE on CMR vs those without had higher odds of ventricular arrhythmias (odds ratio [OR]: 20.3; 95% CI: 8.1-51.0), all-cause mortality (OR: 3.45; 95% CI: 1.6-7.3), and the composite of both (OR: 9.2; 95% CI: 5.1-16.7). Right ventricular LGE is invariably accompanied by left ventricular LGE. Biventricular LGE is also associated with markedly increased odds of ventricular arrhythmias (OR: 43.6; 95% CI: 16.2-117.2). CONCLUSIONS: Patients with known or suspected cardiac sarcoidosis with LGE on CMR have significantly increased odds of both ventricular arrhythmias and all-cause mortality. The presence of biventricular LGE may confer additional prognostic information regarding arrhythmogenic risk.

Protocol for an intervention development and pilot implementation evaluation study of an e-health solution to improve newborn care quality and survival in two low-resource settings, Malawi and Zimbabwe: Neotree.

INTRODUCTION: Every year 2.4 million deaths occur worldwide in babies younger than 28 days. Approximately 70% of these deaths occur in low-resource settings because of failure to implement evidence-based interventions. Digital health technologies may offer an implementation solution. Since 2014, we have worked in Bangladesh, Malawi, Zimbabwe and the UK to develop and pilot Neotree: an android app with accompanying data visualisation, linkage and export. Its low-cost hardware and state-of-the-art software are used to improve bedside postnatal care and to provide insights into population health trends, to impact wider policy and practice. METHODS AND ANALYSIS: This is a mixed methods (1) intervention codevelopment and optimisation and (2) pilot implementation evaluation (including economic evaluation) study. Neotree will be implemented in two hospitals in Zimbabwe, and one in Malawi. Over the 2-year study period clinical and demographic newborn data will be collected via Neotree, in addition to behavioural science informed qualitative and quantitative implementation evaluation and measures of cost, newborn care quality and usability. Neotree clinical decision support algorithms will be optimised according to best available evidence and clinical validation studies. ETHICS AND DISSEMINATION: This is a Wellcome Trust funded project (215742_Z_19_Z). Research ethics approvals have been obtained: Malawi College of Medicine Research and Ethics Committee (P.01/20/2909; P.02/19/2613); UCL (17123/001, 6681/001, 5019/004); Medical Research Council Zimbabwe (MRCZ/A/2570), BRTI and JREC institutional review boards (AP155/2020; JREC/327/19), Sally Mugabe Hospital Ethics Committee (071119/64; 250418/48). Results will be disseminated via academic publications and public and policy engagement activities. In this study, the care for an estimated 15 000 babies across three sites will be impacted. TRIAL REGISTRATION NUMBER: NCT0512707; Pre-results.

Bedside and laboratory diagnostic testing in myasthenia.

Myasthenia gravis (MG) and congenital myasthenic syndromes (CMS) are a group of disorders with a well characterised autoimmune or genetic and neurophysiological basis. We reviewed the literature from the last 20 years assessing the utility of various neurophysiological, immunological, provocative and genetic tests in MG and CMS. Diagnostic sensitivity of repetitive nerve stimulation test ranges between 14 and 94% and specificity between 73 and 100%; sensitivity of single-fibre EMG (SFEMG) test ranges between 64 and 100% and specificity between 22 and 100%; anti-acetylcholine receptor (AChR) antibody sensitivity ranges from 13 to 97% and specificity ranges from 95 to 100%. Overall, SFEMG has the highest sensitivity while positive anti-AChR antibodies have the highest specificity. Newer testing strategies that have been investigated over the last couple of decades include ocular vestibular-evoked myogenic potentials, otoacoustic emissions and disease-specific circulating miRNAs in serum for autoimmune myasthenia, as well as next-generation sequencing for genetic testing of CMS. While there has been significant progress in developing newer testing strategies for diagnosing MG and CMS over the last couple of decades, more research is needed to assess the utility of these newer tools regarding their sensitivity and specificity.

Robotic-Assisted PCI: The Future of Coronary Intervention?

Robotic percutaneous coronary intervention (R-PCI) is a novel approach to performing percutaneous coronary intervention (PCI) whereby the operator can utilise remotely controlled technology to manipulate guidewires and catheter devices. This enables the procedure to be undertaken from within a radiation-shielded cockpit. Success in early trials has led to the release of commercially available robotic platforms which have now received regulatory approval and are available for use in clinical practice. Recent trials evaluating R-PCI have demonstrated high technical success rates with low complication rates. Despite this, a significant number of cases, particularly those with complex anatomy, still require at least partial conversion to a manual procedure. Advantages of R-PCI include accurate stent placement, reduced operator radiation exposure and a presumed reduction in orthopedic injuries. Limitations include current incompatibility with certain intravascular imaging catheters and the inability to manipulate multiple guidewires and stents simultaneously. Patients presenting with ST-elevation myocardial infarction requiring primary-PCI have also largely been excluded from existing R-PCI studies. Given these caveats, R-PCI remains a novel technology and has yet to become commonplace in cardiac catheterisation laboratories, however with increasing safety and feasibility data emerging, it is possible that R-PCI may form part of standard practice in the future.

Limited resources restrict the provision of adequate neonatal respiratory care in the countries of Africa.

AIM: Over two thirds of newborn deaths occur in Africa and South Asia, and respiratory failure is a major contributor of these deaths. The exact availability of continuous positive airway pressure (CPAP) and surfactant in Africa is unknown. The aim of this study was to describe the availability of newborn respiratory care treatments in the countries of Africa. METHODS: Surveys, in English, French and Portuguese, were sent to neonatal leaders in all 48 continental countries and the two islands with populations over 1 million. RESULTS: Forty-nine (98%) countries responded. Twenty-one countries reported less than 50 paediatricians, and 12 countries had no neonatologists. Speciality neonatal nursing was recognised in 57% of countries. Most units were able to provide supplemental oxygen. CPAP was available in 63% and 67% of the most well-equipped government and private hospitals. Surfactant was available in 33% and 39% of the most well-equipped public and private hospitals, respectively. Availability of CPAP and surfactant was greatly reduced in smaller cities. Continuous oxygen saturation monitoring was only available in 33% of countries. CONCLUSION: The availability of proven life-saving interventions in Africa is inadequate. There is a need to sustainably improve availability and use of these interventions.

Intravenous prostanoids in systemic sclerosis-associated pulmonary arterial hypertension: a single-centre experience.

OBJECTIVES: The current study evaluates survival rates among SSc-associated pulmonary arterial hypertension (SSc-PAH) patients on i.v. prostanoids, and short-term impact of i.v. prostanoids on clinical and haemodynamic parameters. METHODS: Baseline demographics, invasive and non-invasive data, European Society of Cardiology (ESC) score and REVEAL score of 81 SSc-PAH patients (median age 61 years, interquartile range 54-67 years, 84% females) were prospectively recorded, from November 2006 till November 2020, before initiation of i.v. prostanoids, and at first formal reassessment. Survival data were retrieved from National Health Service Spine and hospital databases. RESULTS: Significant improvements in clinical and haemodynamic parameters in response to i.v. prostanoid therapy were documented. Functional class (FC) (16.6% improved by 1FC, P =0.041), mean pulmonary arterial pressure (-6.5 mmHg, P =0.036), pulmonary vascular resistance (-2.6 WU, P =0.012), cardiac index (Q/m2) (+0.7 l/min/m2, P =0.003) and mixed venous oxygen saturation (SvO2) (+3%, P =0.036) improved. Estimated survival for CTD-PAH patients on i.v. prostanoids was 64%, 31% and 18%, at 1 year, 3 years and 5 years, respectively. Independent baseline predictors of mortality were older age (HR: 1.043, 95% CI: 1.011-1.075, P =0.007), higher N-terminal pro-brain natriuretic peptide levels (HR: 2.191, 95% CI: 1.131-4.243, P =0.020), and lower SvO2 levels (HR: 0.962, 95% CI: 0.926-0.998, P =0.039). High ESC risk or high and very high REVEAL score was associated with significantly worse survival compared with patients with lower risk scores, both at baseline and when reassessed after a median of 6.5 months. CONCLUSIONS: Survival among SSc-PAH patients on i.v. prostanoids remains poor, risk scoring at baseline and after 6.5 months of therapy improves prognostication.

Dysregulated G2 phase checkpoint recovery pathway reduces DNA repair efficiency and increases chromosomal instability in a wide range of tumours.

Defective DNA repair is being demonstrated to be a useful target in cancer treatment. Currently, defective repair is identified by specific gene mutations, however defective repair is a common feature of cancers without these mutations. DNA damage triggers cell cycle checkpoints that are responsible for co-ordinating cell cycle arrest and DNA repair. Defects in checkpoint signalling components such as ataxia telangiectasia mutated (ATM) occur in a low proportion of cancers and are responsible for reduced DNA repair and increased genomic instability. Here we have investigated the AURKA-PLK1 cell cycle checkpoint recovery pathway that is responsible for exit from the G2 phase cell cycle checkpoint arrest. We demonstrate that dysregulation of PP6 and AURKA maintained elevated PLK1 activation to promote premature exit from only ATM, and not ATR-dependent checkpoint arrest. Surprisingly, depletion of the B55α subunit of PP2A that negatively regulates PLK1 was capable of overcoming ATM and ATR checkpoint arrests. Dysregulation of the checkpoint recovery pathway reduced S/G2 phase DNA repair efficiency and increased genomic instability. We found a strong correlation between dysregulation of the PP6-AURKA-PLK1-B55α checkpoint recovery pathway with signatures of defective homologous recombination and increased chromosomal instability in several cancer types. This work has identified an unrealised source of G2 phase DNA repair defects and chromosomal instability that are likely to be sensitive to treatments targeting defective repair.

COVID-19 preparedness-a survey among neonatal care providers in low- and middle-income countries.

OBJECTIVE: To evaluate COVID-19 pandemic preparedness, available resources, and guidelines for neonatal care delivery among neonatal health care providers in low- and middle-income countries (LMICs) across all continents. STUDY DESIGN: Cross-sectional, web-based survey administered between May and June, 2020. RESULTS: Of 189 invited participants in 69 LMICs, we received 145 (77%) responses from 58 (84%) countries. The pandemic provides significant challenges to neonatal care, particularly in low-income countries. Respondents noted exacerbations of preexisting shortages in staffing, equipment, and isolation capabilities. In Sub-Saharan Africa, 9/35 (26%) respondents noted increased mortality in non-COVID-19-infected infants. Clinical practices on cord clamping, isolation, and breastfeeding varied widely, often not in line with World Health Organization guidelines. Most respondents noted family access restrictions, and limited shared decision-making. CONCLUSIONS: Many LMICs face an exacerbation of preexisting resource challenges for neonatal care during the pandemic. Variable approaches to care delivery and deviations from guidelines provide opportunities for international collaborative improvement.

A Comparison of the Accuracy of Various Methods of Postnatal Gestational Age Estimation; Including Ballard Score, Foot Length, Vascularity of the Anterior Lens, Last Menstrual Period and Also a Clinician's Non-Structured Assessment.

INTRODUCTION: Gestational age is a strong determinant of neonatal mortality and morbidity. Early obstetric ultrasound is the clinical reference standard, but is not widely available in many developing countries. METHODS: A prospectively designed diagnostic accuracy study in a tertiary referral hospital in a developing country. Early ultrasound (<20 weeks) was the clinical reference standard. Methods evaluated included anthropometric measurements (including foot length), vascularity of the anterior lens, the New Ballard Score and last menstrual period. Clinicians' non-structured global impression 'End of Bed' Assessment was also evaluated. RESULTS: 106 babies were included in the study. Median age at birth was 34 weeks (interquartile range 29-36). Ballard Score and 'End of Bed' Assessment had a mean bias of -0.14 and 0.06 weeks respectively but wide 95% limits of agreement. The physical component of the Ballard score, the total Ballard score and Foot length's ability to discriminate between term and preterm infants gave an area under the receiver operating characteristics curve of 0.97, 0.96 and 0.95, respectively. DISCUSSION: Although 'End of Bed' Assessment and Ballard score had small mean biases, the wide confidence intervals render the methods irrelevant in clinical practice. Foot length was particularly poor in Small for Gestational Age infants. None of the methods studied were superior to a non-structured clinician's informal 'End of Bed' Assessment. CONCLUSION: None of the methods studied met the a priori definition of clinical usefulness. Improving access to early ultrasound remains a priority. Instead of focusing on chronological accuracy, future research should compare the ability of early ultrasound and Ballard score to predict morbidity and mortality. Lay summary. BACKGROUND: Gestational age describes the time interval between conception and the delivery of the baby. Babies born before 37 weeks of gestation (preterm) or after 42 weeks of gestation (post-dates) have an increased risk of death and specific illnesses. The best way to estimate the gestational age is to perform an ultrasound scan on the mother before 20 weeks. However, this is not widely available in many developing countries. Methods to estimate gestational age after birth include calculating the time from the last period, various measurements of the child (such as weight, foot length or head circumference) physical and neurological markers of maturity and examination of the blood vessels on the lens in the eye. METHODS: In this study, we assessed how accurate these methods were when compared with the best available method; early ultrasound. We also analyzed the clinicians own personal feeling of what the most likely gestation was, based on an informal 'end of bed' assessment. If a method was to be deemed clinically useful it was agreed that it would have to confidently identify the gestation to within 1 week of the true gestation. RESULTS: None of the methods studied could confidently predict the gestational age of individual babies within 1 week. Ballard scoring and the clinician's informal 'End of Bed' Assessment were the most accurate and also had the smallest inter-operator variability when the results of two separate researchers were compared. Foot length performed particularly badly with babies who were small for their gestational age. CONCLUSION: None of the methods studied confidently predicted gestational age within a week, so have little use in clinical practice. Access to early ultrasound should be improved. Further research into the relationship between maturity markers such as the Ballard score and the rates of death and specific premature related illnesses is warranted.

The use of data in resource limited settings to improve quality of care.

Quality improvement is driven by benchmarking between and within institutions over time and the collaborative improvement efforts that stem from these comparisons. Benchmarking requires systematic collection and use of standardized data. Low- and middle-income countries (LMIC) have great potential for improvements in newborn outcomes but serious obstacles to data collection, analysis, and implementation of robust improvement methodologies exist. We review the importance of data collection, internationally recommended neonatal metrics, selected methods of data collection, and reporting. The transformation from data collection to data use is illustrated by several select data system examples from LMIC. Key features include aims and measures important to neonatal team members, co-development with local providers, immediate access to data for review, and multidisciplinary team involvement. The future of neonatal care, use of data, and the trajectory to reach global neonatal improvement targets in resource-limited settings will be dependent on initiatives led by LMIC clinicians and experts.

Mammary mechanobiology - investigating roles for mechanically activated ion channels in lactation and involution.

The ability of a mother to produce a nutritionally complete neonatal food source has provided a powerful evolutionary advantage to mammals. Milk production by mammary epithelial cells is adaptive, its release is exquisitely timed, and its own glandular stagnation with the permanent cessation of suckling triggers the cell death and tissue remodeling that enables female mammals to nurse successive progeny. Chemical and mechanical signals both play a role in this process. However, despite this duality of input, much remains unknown about the nature and function of mechanical forces in this organ. Here, we characterize the force landscape in the functionally mature gland and the capacity of luminal and basal cells to experience and exert force. We explore molecular instruments for force-sensing, in particular channel-mediated mechanotransduction, revealing increased expression of Piezo1 in mammary tissue in lactation and confirming functional expression in luminal cells. We also reveal, however, that lactation and involution proceed normally in mice with luminal-specific Piezo1 deletion. These findings support a multifaceted system of chemical and mechanical sensing in the mammary gland, and a protective redundancy that ensures continued lactational competence and offspring survival.

Multiscale imaging of basal cell dynamics in the functionally mature mammary gland.

The mammary epithelium is indispensable for the continued survival of more than 5,000 mammalian species. For some, the volume of milk ejected in a single day exceeds their entire blood volume. Here, we unveil the spatiotemporal properties of physiological signals that orchestrate the ejection of milk from alveolar units and its passage along the mammary ductal network. Using quantitative, multidimensional imaging of mammary cell ensembles from GCaMP6 transgenic mice, we reveal how stimulus evoked Ca2+ oscillations couple to contractions in basal epithelial cells. Moreover, we show that Ca2+-dependent contractions generate the requisite force to physically deform the innermost layer of luminal cells, compelling them to discharge the fluid that they produced and housed. Through the collective action of thousands of these biological positive-displacement pumps, each linked to a contractile ductal network, milk begins its passage toward the dependent neonate, seconds after the command.

Pulmonary embolism in acute medicine: a case-based review incorporating latest guidelines in the COVID-19 era.

Pulmonary embolism remains an important cause of morbidity and mortality in the UK, particularly following the outbreak of the novel coronavirus 2019 (COVID-19), where those infected have an increased prevalence of venous thromboembolic events. The pathophysiology in COVID-19 patients is thought to relate to a thromboinflammatory state within the pulmonary vasculature, triggered by the infection, but other risk factors such as reduced mobility, prolonged immobilisation and dehydration are likely to contribute. Several societies have released comprehensive guidelines emphasising the importance of risk stratification in patients with acute pulmonary embolism. They advocate the use of clinically validated risk scores in conjunction with biochemical and imaging results. Patients with mild disease can now be managed in the outpatient setting and with newly developed therapies, such as catheter-directed thrombolysis, becoming available in more centres, treatment options for those with more severe disease are also expanding. This article presents four theoretical but realistic cases, each diagnosed with acute pulmonary embolism, but differing in levels of severity. These demonstrate how the guidelines can be applied in a clinical setting, with particular focus on risk stratification and management.

Class IIa Histone Deacetylases Drive Toll-like Receptor-Inducible Glycolysis and Macrophage Inflammatory Responses via Pyruvate Kinase M2.

Histone deacetylases (HDACs) drive innate immune cell-mediated inflammation. Here we identify class IIa HDACs as key molecular links between Toll-like receptor (TLR)-inducible aerobic glycolysis and macrophage inflammatory responses. A proteomic screen identified the glycolytic enzyme pyruvate kinase M isoform 2 (Pkm2) as a partner of proinflammatory Hdac7 in murine macrophages. Myeloid-specific Hdac7 overexpression in transgenic mice amplifies lipopolysaccharide (LPS)-inducible lactate and promotes a glycolysis-associated inflammatory signature. Conversely, pharmacological or genetic targeting of Hdac7 and other class IIa HDACs attenuates LPS-inducible glycolysis and accompanying inflammatory responses in macrophages. We show that an Hdac7-Pkm2 complex acts as an immunometabolism signaling hub, whereby Pkm2 deacetylation at lysine 433 licenses its proinflammatory functions. Disrupting this complex suppresses inflammatory responses in vitro and in vivo. Class IIa HDACs are thus pivotal intermediates connecting TLR-inducible glycolysis to inflammation via Pkm2.

Melanoma mutations modify melanocyte dynamics in co-culture with keratinocytes or fibroblasts.

Melanocytic cell interactions are integral to skin homeostasis, and affect the outcome of multiple diseases, including cutaneous pigmentation disorders and melanoma. By using automated-microscopy and machine-learning-assisted morphology analysis of primary human melanocytes in co-culture, we performed combinatorial interrogation of melanocyte genotypic variants and functional assessment of lentivirus-introduced mutations. Keratinocyte-induced melanocyte dendricity, an indicator of melanocyte differentiation, was reduced in the melanocortin 1 receptor (MC1R) R/R variant strain and by NRAS.Q61K and BRAF.V600E expression, while expression of CDK4.R24C and RAC1.P29S had no detectable effect. Time-lapse tracking of melanocytes in co-culture revealed dynamic interaction phenotypes and hyper-motile cell states that indicated that, in addition to the known role in activating mitogenic signalling, MEK-pathway-activating mutations may also allow melanocytes to escape keratinocyte control and increase their invasive potential. Expanding this combinatorial platform will identify other therapeutic target mutations and melanocyte genetic variants, as well as increase understanding of skin cell interactions.

Combined use of subclinical hydroxyurea and CHK1 inhibitor effectively controls melanoma and lung cancer progression, with reduced normal tissue toxicity compared to gemcitabine.

Drugs such as gemcitabine that increase replication stress are effective chemotherapeutics in a range of cancer settings. These drugs effectively block replication and promote DNA damage, triggering a cell cycle checkpoint response through the ATR-CHK1 pathway. Inhibiting this signalling pathway sensitises cells to killing by replication stress-inducing drugs. Here, we investigated the effect of low-level replication stress induced by low concentrations (> 0.2 mm) of the reversible ribonucleotide reductase inhibitor hydroxyurea (HU), which slows S-phase progression but has little effect on cell viability or proliferation. We demonstrate that HU effectively synergises with CHK1, but not ATR inhibition, in > 70% of melanoma and non-small-cell lung cancer cells assessed, resulting in apoptosis and complete loss of proliferative potential in vitro and in vivo. Normal fibroblasts and haemopoietic cells retain viability and proliferative potential following exposure to CHK1 inhibitor plus low doses of HU, but normal cells exposed to CHK1 inhibitor combined with submicromolar concentrations of gemcitabine exhibited complete loss of proliferative potential. The effects of gemcitabine on normal tissue correlate with irreversible ATR-CHK1 pathway activation, whereas low doses of HU reversibly activate CHK1 independently of ATR. The combined use of CHK1 inhibitor and subclinical HU also triggered an inflammatory response involving the recruitment of macrophages in vivo. These data indicate that combining CHK1 inhibitor with subclinical HU is superior to combination with gemcitabine, as it provides equal anticancer efficacy but with reduced normal tissue toxicity. These data suggest a significant proportion of melanoma and lung cancer patients could benefit from treatment with this drug combination.