Genetically Encoded Biosensors Reveal PKA Hyperphosphorylation on the Myofilaments in Rabbit Heart Failure

RATIONALE: In heart failure, myofilament proteins display abnormal phosphorylation, which contributes to contractile dysfunction. The mechanisms underlying the dysregulation of protein phosphorylation on myofilaments is not clear. OBJECTIVE: This study aims to understand the mechanisms underlying altered phosphorylation of myofilament proteins in heart failure. METHODS AND RESULTS: We generate a novel genetically encoded protein kinase A (PKA) biosensor anchored onto the myofilaments in rabbit cardiac myocytes to examine PKA activity at the myofilaments in responses to adrenergic stimulation. We show that PKA activity is shifted from the sarcolemma to the myofilaments in hypertrophic failing rabbit myocytes. In particular, the increased PKA activity on the myofilaments is because of an enhanced β2 adrenergic receptor signal selectively directed to the myofilaments together with a reduced phosphodiesterase activity associated with the myofibrils. Mechanistically, the enhanced PKA activity on the myofilaments is associated with downregulation of caveolin-3 in the hypertrophic failing rabbit myocytes. Reintroduction of caveolin-3 in the failing myocytes is able to normalize the distribution of β2 adrenergic receptor signal by preventing PKA signal access to the myofilaments and to restore contractile response to adrenergic stimulation. CONCLUSIONS: In hypertrophic rabbit myocytes, selectively enhanced β2 adrenergic receptor signaling toward the myofilaments contributes to elevated PKA activity and PKA phosphorylation of myofilament proteins. Reintroduction of caveolin-3 is able to confine β2 adrenergic receptor signaling and restore myocyte contractility in response to β adrenergic stimulation

Clinical hypoxemia score for outpatient child pneumonia care lacking pulse oximetry in Africa and South Asia

Background: Pulse oximeters are not routinely available in outpatient clinics in low- and middle-income countries. We derived clinical scores to identify hypoxemic child pneumonia. / Methods: This was a retrospective pooled analysis of two outpatient datasets of 3–35 month olds with World Health Organization (WHO)-defined pneumonia in Bangladesh and Malawi. We constructed, internally validated, and compared fit & discrimination of four models predicting SpO2 < 93% and <90%: (1) Integrated Management of Childhood Illness guidelines, (2) WHO-composite guidelines, (3) Independent variable least absolute shrinkage and selection operator (LASSO); (4) Composite variable LASSO. / Results: 12,712 observations were included. The independent and composite LASSO models discriminated moderately (both C-statistic 0.77) between children with a SpO2 < 93% and ≥94%; model predictive capacities remained moderate after adjusting for potential overfitting (C-statistic 0.74 and 0.75). The IMCI and WHO-composite models had poorer discrimination (C-statistic 0.56 and 0.68) and identified 20.6% and 56.8% of SpO2 < 93% cases. The highest score stratum of the independent and composite LASSO models identified 46.7% and 49.0% of SpO2 < 93% cases. Both LASSO models had similar performance for a SpO2 < 90%. / Conclusions: In the absence of pulse oximeters, both LASSO models better identified outpatient hypoxemic pneumonia cases than the WHO guidelines. Score external validation and implementation are needed

Risk and accuracy of outpatient-identified hypoxaemia for death among suspected child pneumonia cases in rural Bangladesh: a multifacility prospective cohort study

BACKGROUND: Hypoxaemic pneumonia mortality risk in low-income and middle-income countries is high in children who have been hospitalised, but unknown among outpatient children. We sought to establish the outpatient burden, mortality risk, and prognostic accuracy of death from hypoxaemia in children with suspected pneumonia in Bangladesh. METHODS: We conducted a prospective community-based cohort study encompassing three upazila (subdistrict) health complex catchment areas in Sylhet, Bangladesh. Children aged 3-35 months participating in a community surveillance programme and presenting to one of three upazila health complex Integrated Management of Childhood Illness (IMCI) outpatient clinics with an acute illness and signs of difficult breathing (defined as suspected pneumonia) were enrolled in the study; because lower respiratory tract infection mortality mainly occurs in children younger than 1 year, the primary study population comprised children aged 3-11 months. Study physicians recorded WHO IMCI pneumonia guideline clinical signs and peripheral arterial oxyhaemoglobin saturations (SpO2) in room air. They treated children with pneumonia with antibiotics (oral amoxicillin [40 mg/kg per dose twice per day for 5-7 days, as per local practice]), and recommended oxygen, parenteral antibiotics, and hospitalisation for those with an SpO2 of less than 90%, WHO IMCI danger signs, or severe malnutrition. Community health workers documented the children's vital status and the date of any vital status changes during routine household surveillance (one visit to each household every 2 months). The primary outcome was death at 2 weeks after enrolment in children aged 3-11 months (primary study population) and 12-35 months (secondary study population). Primary analyses included estimating the outpatient prevalence, mortality risk, and prognostic accuracy of hypoxaemia for death in children aged 3-11 months with suspected pneumonia. Risk ratios were produced by fitting a multivariable model that regressed predefined SpO2 ranges (<90%, 90-93%, and 94-100%) on the primary 2-week mortality outcome (binary outcome) using Poisson models with robust variance estimation. We established the prognostic accuracy of WHO IMCI guidelines for death with and without varying SpO2 thresholds. FINDINGS: Participants were recruited between Sept 1, 2015, to Aug 31, 2017. During the study period, a total of 7440 children aged 3-35 months with the first suspected pneumonia episode were enrolled, of whom 3848 (54·3%) with an attempted pulse oximeter measurement and 2-week outcome were included in our primary study population of children aged 3-11-months. Among children aged 3-11 months, an SpO2 of less than 90% occurred in 102 (2·7%) of 3848 children, an SpO2 of 90-93% occurred in 306 (8·0%) children, a failed SpO2 measurement occurred in 67 (1·7%) children, and 24 (0·6%) children with suspected pneumonia died. Compared with an SpO2 of 94-100% (3373 [87·7%] of 3848), the adjusted risk ratio for death was 10·3 (95% CI 3·2-32·3; p<0·001) for an SpO2 of less than 90%, 4·3 (1·5-11·8; p=0·005) for an SpO2 of 90-93%, and 11·4 (3·1-41·4; p<0·001) for a failed measurement. When not considering pulse oximetry, of the children who died, WHO IMCI guidelines identified only 25·0% (95% CI 9·7-46·7; six of 24 children) as eligible for referral to hospital. For identifying deaths, in children with an SpO2 of less than 90% WHO IMCI guidelines had a 41·7% sensitivity (95% CI 22·1-63·4) and 89·7% specificity (88·7-90·7); for children with an SpO2 of less than 90% or measurement failure the guidelines had a 54·2% sensitivity (32·8-74·4) and 88·3% specificity (87·2-89·3); and for children with an SpO2 of less than 94% or measurement failure the guidelines had a 62·5% sensitivity (40·6-81·2) and 81·3% specificity (80·0-82·5). INTERPRETATION: These findings support pulse oximeter use during the outpatient care of young children with suspected pneumonia in Bangladesh as well as the re-evaluation of the WHO IMCI currently recommended threshold of an SpO2 less than 90% for hospital referral. FUNDING: Fogarty International Center of the National Institutes of Health (K01TW009988), The Bill & Melinda Gates Foundation (OPP1084286 and OPP1117483), and GlaxoSmithKline (90063241)

Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005

BACKGROUND The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. METHODOLOGY/PRINCIPAL FINDINGS Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. CONCLUSIONS/SIGNIFICANCE Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.This work was partially supported by salaries from the NOAA Coral Reef Conservation Program to the NOAA Coral Reef Conservation Program authors. NOAA provided funding to Caribbean ReefCheck investigators to undertake surveys of bleaching and mortality. Otherwise, no funding from outside authors' institutions was necessary for the undertaking of this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Clinical hypoxemia score for outpatient child pneumonia care lacking pulse oximetry in Africa and South Asia

BackgroundPulse oximeters are not routinely available in outpatient clinics in low- and middle-income countries. We derived clinical scores to identify hypoxemic child pneumonia.MethodsThis was a retrospective pooled analysis of two outpatient datasets of 3–35 month olds with World Health Organization (WHO)-defined pneumonia in Bangladesh and Malawi. We constructed, internally validated, and compared fit &amp; discrimination of four models predicting SpO2 &lt; 93% and &lt;90%: (1) Integrated Management of Childhood Illness guidelines, (2) WHO-composite guidelines, (3) Independent variable least absolute shrinkage and selection operator (LASSO); (4) Composite variable LASSO.Results12,712 observations were included. The independent and composite LASSO models discriminated moderately (both C-statistic 0.77) between children with a SpO2 &lt; 93% and ≥94%; model predictive capacities remained moderate after adjusting for potential overfitting (C-statistic 0.74 and 0.75). The IMCI and WHO-composite models had poorer discrimination (C-statistic 0.56 and 0.68) and identified 20.6% and 56.8% of SpO2 &lt; 93% cases. The highest score stratum of the independent and composite LASSO models identified 46.7% and 49.0% of SpO2 &lt; 93% cases. Both LASSO models had similar performance for a SpO2 &lt; 90%.ConclusionsIn the absence of pulse oximeters, both LASSO models better identified outpatient hypoxemic pneumonia cases than the WHO guidelines. Score external validation and implementation are needed