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Levin JC, Curtis CJ, Woodford DJ. A multi-spatial scale assessment of land-use stress on water quality in headwater streams in the Platinum Belt, South Africa. Sci Total Environ 2024; 927:172180. [PMID: 38580113 DOI: 10.1016/j.scitotenv.2024.172180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 03/28/2024] [Accepted: 04/01/2024] [Indexed: 04/07/2024]
Abstract
River water quality is affected by various stressors (land-uses) operating at different hydrological spatial scales. Few studies have employed a multi-scaled analyses to differentiate effects of natural grasslands and woodlands, agriculture, impoundments, urban and mining stressors on headwater streams. Using a multi-scaled modeling approach, this study disentangled the distinct spatial signatures and mechanistic effects of specific stressors and topographic drivers on individual water quality parameters in tributaries of the Gwathle River Catchment in the Platinum Belt of South Africa. Water samples were collected on six occasions from 15 sites on three rivers over 12-months. Physio-chemical parameters as well as major anions, cations and metals were measured. Five key water quality parameters were identified using principal components analysis: sulfate, ammonium, copper, turbidity, and pH to characterise catchment water quality conditions. Using class-level composition (PLAND) and connectedness (COHESION) metrics together with topographic data, generalized linear mixed models were developed at multiple scales (sub-basin, cumulative catchment, riparian buffers) to identify the most parsimonious model with the dominant drivers of each water quality parameter. Ammonium concentrations were best explained by urban stress, Cu increased with mining and agriculture, turbidity increased with elevation heterogeneity, agriculture, urbanisation and fallow lands all at the sub-basin scale. River pH was positively predicted by slope heterogeneity, mining cover and impoundment connectivity at the catchment scale. Sulfate increased with mining and agriculture composition in the 100 m riparian buffer. Hierarchical cluster analysis of water quality and scale-dependent parsimonious drivers separated the river sites into three distinct groups distinguishing pristine, moderately impacted, and heavily mined sites. By demonstrating stressor- and scale-dependent water quality responses, this multi-scale nested modeling approach reveals the importance of developing adaptive, targeted management plans at hydrologically meaningful scales to sustain water quality amid intensifying land use.
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Affiliation(s)
- Jonathan C Levin
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - Christopher J Curtis
- School of Geography, Environmental Management and Energy Studies, University of Johannesburg, Johannesburg, South Africa
| | - Darragh J Woodford
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa; South African Institute for Aquatic Biodiversity, Makhanda, South Africa
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Levin JC, Beam AL, Fox KP, Hayden LP. Cost Savings Without Increased Risk of Respiratory Hospitalization for Preterm Children after the 2014 Palivizumab Policy Update. Am J Perinatol 2024; 41:e133-e141. [PMID: 35523410 PMCID: PMC9969323 DOI: 10.1055/a-1845-2184] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
OBJECTIVES Our objective was to compare rates of hospitalizations for respiratory illnesses in preterm and full-term (FT) children for 4 years before and after the 2014 update to the American Academy of Pediatrics (AAP) respiratory syncytial virus (RSV) immunoprophylaxis guidance, which restricted eligibility among infants born at 29 to 34 weeks in the first winter and all preterm infants in the second winter after neonatal discharge. STUDY DESIGN We conducted pre-post and interrupted time series analyses on claims data from a commercial national managed care plan. We compared the number of RSV and all respiratory hospital admissions in the first and second RSV seasons after neonatal discharge among a cohort of preterm children, regardless of palivizumab status, in the 4 years before and after the implementation of the 2014 palivizumab eligibility change. A FT group was included for reference. RESULTS The cohort included 821 early preterm (EP, <29 weeks), 4,790 moderate preterm (MP, 29-34 weeks), and 130,782 FT children. Palivizumab use after the policy update decreased among MP children in the first and second RSV seasons after neonatal discharge, without any change in the odds of hospitalization with RSV or respiratory illness. For the EP group, there was no change in the rate of palivizumab or the odds of hospitalization with RSV or respiratory illness after the policy update. For the FT group, there was a slight decrease in odds of hospitalization post-2014 after the policy update. The interrupted time series did not reveal any secular trends over time in hospitalization rates among preterm children. Following the policy change, there were cost savings for MP children in the first and second RSV seasons, when accounting for the cost of hospitalizations and the cost of palivizumab. CONCLUSION Hospitalizations for RSV or respiratory illness did not increase, and cost savings were obtained after the implementation of the 2014 AAP palivizumab prophylaxis policy. KEY POINTS · Palivizumab use decreased among children born moderate preterm (29 to34 weeks) after the 2014 palivizuamb policy update.. · There was no change in odds of hospitalization with respiratory syncitial virus or respiratory illness among preterm infants after the policy update when compared to before.. · There were cost savings, when accounting for the cost of hospitalizations and the cost of palivizumab, after the policy update among children born moderate preterm..
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Affiliation(s)
- Jonathan C. Levin
- Division of Newborn Medicine, Boston Children’s
Hospital, Boston MA
- Division of Pulmonary Medicine, Boston Children’s
Hospital, Boston MA
| | - Andrew L. Beam
- Department of Epidemiology, Harvard T.H. Chan School of
Public Health, Boston MA
| | - Kathe P. Fox
- Department of Biomedical Informatics, Harvard Medical
School, Boston, MA
| | - Lystra P. Hayden
- Division of Pulmonary Medicine, Boston Children’s
Hospital, Boston MA
- Channing Division of Network Medicine, Brigham and
Women’s Hospital, Boston, MA
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Collaco JM, Tsukahara KR, Tracy MC, Sheils CA, Rice JL, Rhein LM, Popova AP, Nelin L, Miller AN, Manimtim WM, Levin JC, Lai K, Kaslow JA, Hayden LP, Bansal M, Austin ED, Aoyama B, Akangire G, Agarwal A, Villafranco N, McGrath-Morrow SA. Number of children in the household influences respiratory morbidities in children with bronchopulmonary dysplasia in the outpatient setting. Pediatr Pulmonol 2024; 59:314-322. [PMID: 37937888 PMCID: PMC10872663 DOI: 10.1002/ppul.26747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 09/20/2023] [Accepted: 10/28/2023] [Indexed: 11/09/2023]
Abstract
BACKGROUND Bronchopulmonary dysplasia (BPD), a common complication of prematurity, is associated with outpatient morbidities, including respiratory exacerbations. Daycare attendance is associated with increased rates of acute and chronic morbidities in children with BPD. We sought to determine if additional children in the household conferred similar risks for children with BPD. METHODS The number of children in the household and clinical outcomes were obtained via validated instruments for 933 subjects recruited from 13 BPD specialty clinics in the United States. Clustered logistic regression models were used to test for associations. RESULTS The mean gestational age of the study population was 26.5 ± 2.2 weeks and most subjects (69.1%) had severe BPD. The mean number of children in households (including the subject) was 2.1 ± 1.3 children. Each additional child in the household was associated with a 13% increased risk for hospital admission, 13% increased risk for antibiotic use for respiratory illnesses, 10% increased risk for coughing/wheezing/shortness of breath, 14% increased risk for nighttime symptoms, and 18% increased risk for rescue medication use. Additional analyses found that the increased risks were most prominent when there were three or more other children in the household. CONCLUSIONS We observed that additional children in the household were a risk factor for adverse respiratory outcomes. We speculate that secondary person-to-person transmission of respiratory viral infections drives this finding. While this risk factor is not easily modified, measures do exist to mitigate this disease burden. Further studies are needed to define best practices for mitigating this risk associated with household viral transmission.
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Affiliation(s)
- Joseph M. Collaco
- Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins University, Baltimore, MD
| | - Katharine R. Tsukahara
- Division of Pediatric Pulmonary and Sleep Medicine, University of Utah, Salt Lake City, UT
| | - Michael C. Tracy
- Division of Pediatric Pulmonary, Asthma and Sleep Medicine, Stanford University, Stanford, CA
| | - Catherine A. Sheils
- Division of Pulmonary Medicine, Boston Children’s Hospital and Harvard Medical School, Boston, MA
| | - Jessica L. Rice
- Division of Pulmonary Medicine, Children’s Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA
| | - Lawrence M Rhein
- Neonatal-Perinatal Medicine/Pediatric Pulmonology, University of Massachusetts, Worcester, MA
| | | | - Leif Nelin
- Division of Neonatology, Nationwide Children’s Hospital and Ohio State University, Columbus, OH
| | - Audrey N. Miller
- Division of Neonatology, Nationwide Children’s Hospital and Ohio State University, Columbus, OH
| | - Winston M. Manimtim
- Division of Neonatology, Children’s Mercy-Kansas City and University of Missouri Kansas City School of Medicine
| | - Jonathan C. Levin
- Division of Pulmonary Medicine, Boston Children’s Hospital and Harvard Medical School, Boston, MA
- Division of Newborn Medicine, Boston Children’s Hospital and Harvard Medical School, Boston, MA
| | - Khanh Lai
- Division of Pediatric Pulmonary and Sleep Medicine, University of Utah, Salt Lake City, UT
| | - Jacob A. Kaslow
- Pulmonary Medicine, Vanderbilt University and Vanderbilt University Medical Center, Nashville, TN
| | - Lystra P. Hayden
- Division of Pulmonary Medicine, Boston Children’s Hospital and Harvard Medical School, Boston, MA
| | - Manvi Bansal
- Pulmonology and Sleep Medicine, Children’s Hospital of Los Angeles, Los Angeles, CA
| | - Eric D. Austin
- Pulmonary Medicine, Vanderbilt University and Vanderbilt University Medical Center, Nashville, TN
| | - Brianna Aoyama
- Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins University, Baltimore, MD
| | - Gangaram Akangire
- Division of Neonatology, Children’s Mercy-Kansas City and University of Missouri Kansas City School of Medicine
| | - Amit Agarwal
- Division of Pulmonary Medicine, Arkansas Children’s Hospital and University of Arkansas for Medical Sciences, Little Rock, AR
| | - Natalie Villafranco
- Pulmonary Medicine, Texas Children’s Hospital and Baylor College of Medicine, Houston, TX
| | - Sharon A. McGrath-Morrow
- Division of Pulmonary Medicine, Children’s Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA
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Levin JC, Kielt MJ, Hayden LP, Conroy S, Truog WE, Guaman MC, Abman SH, Nelin LD, Rosen RL, Leeman KT. Transpyloric feeding is associated with adverse in-hospital outcomes in infants with severe bronchopulmonary dysplasia. J Perinatol 2024; 44:307-313. [PMID: 38218908 DOI: 10.1038/s41372-024-01867-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 11/09/2023] [Accepted: 01/02/2024] [Indexed: 01/15/2024]
Abstract
OBJECTIVE To estimate the association of transpyloric feeding (TPF) with the composite outcome of tracheostomy or death for patients with severe bronchopulmonary dysplasia (sBPD). STUDY DESIGN Retrospective multi-center cohort study of preterm infants <32 weeks with sBPD receiving enteral feedings. We compared infants who received TPF at 36, 44, or 50 weeks post-menstrual age to those who did not receive TPF at any of those timepoints. Odds ratios were adjusted for gestational age, small for gestational age, male sex, and invasive ventilation and FiO2 at 36 weeks. RESULTS Among 1039 patients, 129 (12%) received TPF. TPF was associated with an increased odds of tracheostomy or death (aOR 3.5, 95% CI 2.0-6.1) and prolonged length of stay or death (aOR 3.1, 95% CI 1.9-5.2). CONCLUSIONS Use of TPF in sBPD after 36 weeks was infrequent and associated with worse in-hospital outcomes, even after adjusting for respiratory severity at 36 weeks.
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Affiliation(s)
- Jonathan C Levin
- Boston Children's Hospital and Harvard Medical School, Boston, MA, USA.
| | - Matthew J Kielt
- Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, OH, USA
| | - Lystra P Hayden
- Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Sara Conroy
- Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, OH, USA
| | - William E Truog
- Children's Mercy Hospital and University of Missouri-Kansas City School of Medicine, Kansas City, MO, USA
| | | | - Steven H Abman
- Children's Hospital Colorado and University of Colorado School of Medicine, Aurora, CO, USA
| | - Leif D Nelin
- Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, OH, USA
| | - Rachel L Rosen
- Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Kristen T Leeman
- Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
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Kielt MJ, Levin JC. To Trach or Not To Trach: Long-term Tracheostomy Outcomes in Infants with BPD. Neoreviews 2023; 24:e704-e719. [PMID: 37907398 DOI: 10.1542/neo.24-11-e704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
See Bonus NeoBriefs videos and downloadable teaching slides Infants born preterm who are diagnosed with bronchopulmonary dysplasia (BPD) demonstrate a wide spectrum of illness severity. For infants with the most severe forms of BPD, safe discharge from the hospital may only be possible by providing long-term ventilation via a surgically placed tracheostomy. Though tracheostomy placement in infants with BPD is infrequent, recent reports suggest that rates of tracheostomy placement are increasing in this population. Even though there are known respiratory and neurodevelopmental risks associated with tracheostomy placement, no evidence-based criteria or consensus clinical practice guidelines exist to inform tracheostomy placement in this growing and vulnerable population. An incomplete knowledge of long-term post-tracheostomy outcomes in infants with BPD may unduly bias medical decision-making and family counseling regarding tracheostomy placement. This review aims to summarize our current knowledge of the epidemiology and long-term outcomes of tracheostomy placement in infants with BPD to provide a family-centered framework for tracheostomy counseling.
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Affiliation(s)
- Matthew J Kielt
- Comprehensive Center for Bronchopulmonary Dysplasia, Nationwide Children's Hospital, Columbus, OH
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH
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Kielt MJ, Hatch LD, Levin JC, Napolitano N, Abman SH, Baker CD, Eldredge LC, Collaco JM, McGrath-Morrow SA, Rose RS, Lai K, Keszler M, Sindelar R, Nelin LD, McKinney RL. Classifying multicenter approaches to invasive mechanical ventilation for infants with bronchopulmonary dysplasia using hierarchical clustering analysis. Pediatr Pulmonol 2023; 58:2323-2332. [PMID: 37265416 DOI: 10.1002/ppul.26488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 04/07/2023] [Accepted: 05/09/2023] [Indexed: 06/03/2023]
Abstract
INTRODUCTION Evidence-based ventilation strategies for infants with severe bronchopulmonary dysplasia (BPD) remain unknown. Determining whether contemporary ventilation approaches cluster as specific BPD strategies may better characterize care and enhance the design of clinical trials. The objective of this study was to test the hypothesis that unsupervised, multifactorial clustering analysis of point prevalence ventilator setting data would classify a discrete number of physiology-based approaches to mechanical ventilation in a multicenter cohort of infants with severe BPD. METHODS We performed a secondary analysis of a multicenter point prevalence study of infants with severe BPD treated with invasive mechanical ventilation. We clustered the cohort by mean airway pressure (MAP), positive end expiratory pressure (PEEP), set respiratory rate, and inspiratory time (Ti) using Ward's hierarchical clustering analysis (HCA). RESULTS Seventy-eight patients with severe BPD were included from 14 centers. HCA classified three discrete clusters as determined by an agglomerative coefficient of 0.97. Cluster stability was relatively strong as determined by Jaccard coefficient means of 0.79, 0.85, and 0.77 for clusters 1, 2, and 3, respectively. The median PEEP, MAP, rate, Ti, and PIP differed significantly between clusters for each comparison by Kruskall-Wallis testing (p < 0.0001). CONCLUSIONS In this study, unsupervised clustering analysis of ventilator setting data identified three discrete approaches to mechanical ventilation in a multicenter cohort of infants with severe BPD. Prospective trials are needed to determine whether these approaches to mechanical ventilation are associated with specific severe BPD clinical phenotypes and differentially modify respiratory outcomes.
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Affiliation(s)
- Matthew J Kielt
- Division of Neonatology, Department of Pediatrics, Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - L Dupree Hatch
- Mildred Stahlman Division of Neonatology, Department of Pediatrics, Monroe Carrell Jr Children's Hospital at Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jonathan C Levin
- Divisions of Pulmonary and Newborn Medicine, Boston Children's Hospital and Harvard University Medical School, Boston, Massachusetts, USA
| | - Natalie Napolitano
- Department of Respiratory Care, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Steven H Abman
- Section of Pulmonary and Sleep Medicine, Pediatric Heart Lung Center, Department of Pediatrics, Children's Hospital Colorado and the University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Christopher D Baker
- Section of Pulmonary and Sleep Medicine, Pediatric Heart Lung Center, Department of Pediatrics, Children's Hospital Colorado and the University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Laurie C Eldredge
- Division of Pulmonary and Sleep Medicine, Department of Pediatrics, Seattle Children's Hospital and the University of Washington School of Medicine, Seattle, Washington, USA
| | - Joseph M Collaco
- Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Sharon A McGrath-Morrow
- Division of Pulmonary and Sleep Medicine, Children's Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, Philadelphia, USA
| | - Rebecca S Rose
- Division of Neonatology, Department of Pediatrics, Riley Children's Hospital and Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Khanh Lai
- Division of Pediatric Pulmonary and Sleep Medicine, Primary Children's Hospital and the University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Martin Keszler
- Division of Neonatology, Department of Pediatrics, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | - Richard Sindelar
- Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden
| | - Leif D Nelin
- Division of Neonatology, Department of Pediatrics, Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Robin L McKinney
- Division of Pediatric Critical Care Medicine, Department of Pediatrics, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
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7
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Levin JC, Sheils CA, Hayden LP. Pre-Flight Hypoxemia Challenge Testing in Bronchopulmonary Dysplasia. Pediatrics 2023:e2022061001. [PMID: 37503557 PMCID: PMC10389772 DOI: 10.1542/peds.2022-061001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/17/2023] [Indexed: 07/29/2023] Open
Abstract
BACKGROUND AND OBJECTIVES Former premature infants with bronchopulmonary dysplasia (BPD) are at risk for hypoxemia during air travel, but it is unclear until what age. We aimed to determine pass rates for high altitude simulation testing (HAST) by age in children with BPD and identify risks for failure. METHODS Retrospective, observational analysis of HAST in children with BPD at Boston Children's Hospital, using interval censoring to estimate the time-to-event curve of first pass. Curves were stratified by neonatal risk factors. Pass was considered lowest Spo2 ≥ 90%, or ≥94% for subjects with ongoing pulmonary hypertension (PH). RESULTS Ninety four HAST studies were analyzed from 63 BPD subjects; 59 studies (63%) were passed. At 3 months corrected gestational age (CGA), 50% of subjects had passed; at 6 months CGA, 67% has passed; at 12 and 18 months CGA, 72% had passed; and at 24 months CGA, 85% had passed. Neonatal factors associated with delayed time-to-pass included postnatal corticosteroid use, respiratory support at NICU discharge, and tracheostomy. BPD infants who did not require respiratory support at 36 weeks were likely to pass (91%) at 6 months CGA. At 24 months, children least likely to pass included those with a history of PH (63%) and those discharged from the NICU with oxygen or respiratory support (71%). CONCLUSIONS Children with BPD on respiratory support at 36 weeks should be considered for preflight hypoxemia challenges through at least 24 months CGA, and longer if they had PH or went home from NICU on respiratory support.
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Affiliation(s)
- Jonathan C Levin
- Division of Newborn Medicine, Boston Children's Hospital, Boston, Massachusetts
- Division of Pulmonary Medicine, Boston Children's Hospital, Boston, Massachusetts; and
| | - Catherine A Sheils
- Division of Pulmonary Medicine, Boston Children's Hospital, Boston, Massachusetts; and
| | - Lystra P Hayden
- Division of Pulmonary Medicine, Boston Children's Hospital, Boston, Massachusetts; and
- Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, Massachusetts
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8
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Manimtim WM, Agarwal A, Alexiou S, Levin JC, Aoyama B, Austin ED, Bansal M, Bauer SE, Cristea AI, Fierro JL, Garey DM, Hayden LP, Kaslow JA, Miller AN, Moore PE, Nelin LD, Popova AP, Rice JL, Tracy MC, Baker CD, Dawson SK, Eldredge LC, Lai K, Rhein LM, Siddaiah R, Villafranco N, McGrath-Morrow SA, Collaco JM. Respiratory Outcomes for Ventilator-Dependent Children With Bronchopulmonary Dysplasia. Pediatrics 2023; 151:e2022060651. [PMID: 37122061 PMCID: PMC10158083 DOI: 10.1542/peds.2022-060651] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/07/2023] [Indexed: 05/02/2023] Open
Abstract
OBJECTIVES To describe outpatient respiratory outcomes and center-level variability among children with severe bronchopulmonary dysplasia (BPD) who require tracheostomy and long-term mechanical ventilation. METHODS Retrospective cohort of subjects with severe BPD, born between 2016 and 2021, who received tracheostomy and were discharged on home ventilator support from 12 tertiary care centers participating in the BPD Collaborative Outpatient Registry. Timing of key respiratory events including time to tracheostomy placement, initial hospital discharge, first outpatient clinic visit, liberation from the ventilator, and decannulation were assessed using Kaplan-Meier analysis. Differences between centers for the timing of events were assessed via log-rank tests. RESULTS There were 155 patients who met inclusion criteria. Median age at the time of the study was 32 months. The median age of tracheostomy placement was 5 months (48 weeks' postmenstrual age). The median ages of hospital discharge and first respiratory clinic visit were 10 months and 11 months of age, respectively. During the study period, 64% of the subjects were liberated from the ventilator at a median age of 27 months and 32% were decannulated at a median age of 49 months. The median ages for all key events differed significantly by center (P ≤ .001 for all events). CONCLUSIONS There is wide variability in the outpatient respiratory outcomes of ventilator-dependent infants and children with severe BPD. Further studies are needed to identify the factors that contribute to variability in practice among the different BPD outpatient centers, which may include inpatient practices.
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Affiliation(s)
- Winston M. Manimtim
- Division of Neonatology, Children’s Mercy-Kansas City and University of Missouri Kansas City School of Medicine, Kansas City, Missouri
| | - Amit Agarwal
- Division of Pulmonary Medicine, Arkansas Children’s Hospital and University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Stamatia Alexiou
- Division of Pulmonary Medicine, Children’s Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jonathan C. Levin
- Division of Pulmonary Medicine, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Brianna Aoyama
- Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins University, Baltimore, Maryland
| | - Eric D. Austin
- Pulmonary Medicine, Vanderbilt University and Vanderbilt University Medical Center, Nashville, Tennessee
| | - Manvi Bansal
- Pulmonology and Sleep Medicine, Children’s Hospital of Los Angeles, Los Angeles, California
| | - Sarah E. Bauer
- Division of Pediatric Pulmonology, Allergy and Sleep Medicine, Riley Children’s Hospital and Indiana University, Indianapolis, Indiana
| | - A. Ioana Cristea
- Division of Pediatric Pulmonology, Allergy and Sleep Medicine, Riley Children’s Hospital and Indiana University, Indianapolis, Indiana
| | - Julie L. Fierro
- Division of Pulmonary Medicine, Children’s Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania
| | - Donna M. Garey
- Department of Pediatrics, Creighton University School of Medicine, Phoenix Regional Campus, Phoenix, Arizona
| | - Lystra P. Hayden
- Division of Pulmonary Medicine, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Jacob A. Kaslow
- Pulmonary Medicine, Vanderbilt University and Vanderbilt University Medical Center, Nashville, Tennessee
| | - Audrey N. Miller
- Division of Neonatology, Nationwide Children’s Hospital and Ohio State University, Columbus, Ohio
| | - Paul E. Moore
- Pulmonology and Sleep Medicine, Children’s Hospital of Los Angeles, Los Angeles, California
| | - Leif D. Nelin
- Division of Neonatology, Nationwide Children’s Hospital and Ohio State University, Columbus, Ohio
| | | | - Jessica L. Rice
- Division of Pulmonary Medicine, Children’s Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania
| | - Michael C. Tracy
- Division of Pediatric Pulmonary, Asthma and Sleep Medicine, Stanford University, Stanford, California
| | - Christopher D. Baker
- Section of Pulmonary and Sleep Medicine, Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado
| | - Sara K. Dawson
- Department of Pediatrics, Medical College of Wisconsin Milwaukee, Wisconsin
| | - Laurie C. Eldredge
- Division of Pediatric Pulmonary and Sleep Medicine, University of Washington, Seattle, Washington
| | - Khanh Lai
- Division of Pediatric Pulmonary and Sleep Medicine, University of Utah, Salt Lake City, Utah
| | - Lawrence M. Rhein
- Neonatal-Perinatal Medicine/Pediatric Pulmonology, University of Massachusetts, Worcester, Massachusetts
| | - Roopa Siddaiah
- Pediatric Pulmonology, Penn State Health, Hershey Pennsylvania
| | - Natalie Villafranco
- Pulmonary Medicine, Texas Children’s Hospital and Baylor University, Houston, Texas
| | - Sharon A. McGrath-Morrow
- Division of Pulmonary Medicine, Children’s Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania
| | - Joseph M. Collaco
- Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins University, Baltimore, Maryland
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Stickney CA, Levy PT, Abecassis L, Levin JC. Beyond the NICU: Comprehensive management of infants with bronchopulmonary dysplasia in the PICU. Pediatr Pulmonol 2023; 58:1602-1606. [PMID: 36840405 DOI: 10.1002/ppul.26364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 02/15/2023] [Accepted: 02/17/2023] [Indexed: 02/26/2023]
Affiliation(s)
- Carolyn A Stickney
- Division of Medical Critical Care, Boston Children's Hospital, Boston, Massachusetts, USA.,Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Philip T Levy
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA.,Division of Newborn Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Leah Abecassis
- Cardiovascular and Critical Care Nursing, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Jonathan C Levin
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA.,Division of Newborn Medicine, Boston Children's Hospital, Boston, Massachusetts, USA.,Division of Pulmonary Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
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Natarajan A, Lam G, Liu J, Beam AL, Beam KS, Levin JC. Prediction of extubation failure among low birthweight neonates using machine learning. J Perinatol 2023; 43:209-214. [PMID: 36611107 PMCID: PMC10348822 DOI: 10.1038/s41372-022-01591-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 12/09/2022] [Accepted: 12/14/2022] [Indexed: 01/09/2023]
Abstract
OBJECTIVE To develop machine learning models predicting extubation failure in low birthweight neonates using large amounts of clinical data. STUDY DESIGN Retrospective cohort study using MIMIC-III, a large single-center, open-source clinical dataset. Logistic regression and boosted-tree (XGBoost) models using demographics, medications, and vital sign and ventilatory data were developed to predict extubation failure, defined as reintubation within 7 days. RESULTS 1348 low birthweight (≤2500 g) neonates who received mechanical ventilation within the first 7 days were included, of which 350 (26%) failed a trial of extubation. The best-performing model was a boosted-tree model incorporating demographics, vital signs, ventilator parameters, and medications (AUROC 0.82). The most important features were birthweight, last FiO2, average mean airway pressure, caffeine use, and gestational age. CONCLUSIONS Machine learning models identified low birthweight ventilated neonates at risk for extubation failure. These models will need to be validated across multiple centers to determine generalizability of this tool.
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Affiliation(s)
| | - Grace Lam
- Department of Computer Science, Stanford University, Palo Alto, CA, USA
| | - Jingyi Liu
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Andrew L Beam
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
- CAUSALab, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Kristyn S Beam
- Department of Neonatology, Beth Israel Deaconess Medical Center, Boston, MA, USA
- Division of Newborn Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Jonathan C Levin
- Department of Neonatology, Beth Israel Deaconess Medical Center, Boston, MA, USA.
- Division of Newborn Medicine, Boston Children's Hospital, Boston, MA, USA.
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11
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Levin JC, Annesi CA, Williams DN, Abman SH, McGrath-Morrow SA, Nelin LD, Sheils CA, Hayden LP. Discharge Practices for Infants with Bronchopulmonary Dysplasia: A Survey of National Experts. J Pediatr 2023; 253:72-78.e3. [PMID: 36126730 PMCID: PMC10423686 DOI: 10.1016/j.jpeds.2022.09.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 09/11/2022] [Accepted: 09/14/2022] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To establish consensus practices among a panel of national experts for the discharge of premature infants with bronchopulmonary dysplasia (BPD) from the hospital to home. STUDY DESIGN We conducted a Delphi study that included US neonatologists and pediatric pulmonologists from the Bronchopulmonary Dysplasia Collaborative to establish consensus practices-defined as recommendations with at least 80% agreement-for infants with BPD being discharged from the hospital. Specifically, we evaluated recommendations for diagnostic tests to be completed around discharge, follow-up respiratory care, and family education. RESULTS Thirty-one expert participants completed 3 rounds of surveys, with a 99% response rate (92 of 93). Consensus was established that infants with moderate-severe BPD (ie, those who remain on respiratory support at 36 weeks) and those discharged on oxygen should be targeted for in-person pulmonary follow-up within 1 month of hospital discharge. Specialized neonatal follow-up is an alternative for infants with mild BPD. Infants with moderate or severe BPD should have an echocardiogram performed after 36 weeks to screen for pulmonary hypertension. Infants with BPD warrant additional evaluations if they have growth restriction or poor growth, pulmonary hypertension, or tachypnea and if they are discharged to home on oxygen, diuretics, or nonoral feeds. CONCLUSIONS This Delphi survey establishes expert consensus around best practices for follow-up respiratory management and routine evaluation for infants with BPD surrounding neonatal discharge. Areas of disagreement for which consensus was not established are discussed.
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Affiliation(s)
- Jonathan C Levin
- Division of Pulmonary Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA; Division of Newborn Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA.
| | | | - David N Williams
- Institutional Centers for Clinical and Translational Research, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Steven H Abman
- Department of Pediatrics Section of Pulmonary and Sleep Medicine, University of Colorado Anschutz Medical Center and Children's Hospital Colorado, Aurora, CO
| | - Sharon A McGrath-Morrow
- Division of Pulmonary and Sleep, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Leif D Nelin
- Division of Neonatology, Nationwide Children's Hospital, The Ohio State University, Columbus, OH
| | - Catherine A Sheils
- Division of Pulmonary Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Lystra P Hayden
- Division of Pulmonary Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA
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12
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McGrath-Morrow SA, Agarwal A, Alexiou S, Austin ED, Fierro JL, Hayden LP, Lai K, Levin JC, Manimtim WM, Moore PE, Rhein LM, Rice JL, Sheils CA, Tracy MC, Bansal M, Baker CD, Cristea AI, Popova AP, Siddaiah R, Villafranco N, Nelin LD, Collaco JM. Daycare Attendance is Linked to Increased Risk of Respiratory Morbidities in Children Born Preterm with Bronchopulmonary Dysplasia. J Pediatr 2022; 249:22-28.e1. [PMID: 35803300 PMCID: PMC10588550 DOI: 10.1016/j.jpeds.2022.06.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 05/06/2022] [Accepted: 06/05/2022] [Indexed: 10/17/2022]
Abstract
OBJECTIVES To test the hypothesis that daycare attendance among children with bronchopulmonary dysplasia (BPD) is associated with increased chronic respiratory symptoms and/or greater health care use for respiratory illnesses during the first 3 years of life. STUDY DESIGN Daycare attendance and clinical outcomes were obtained via standardized instruments for 341 subjects recruited from 9 BPD specialty clinics in the US. All subjects were former infants born preterm (<34 weeks) with BPD (71% severe) requiring outpatient follow-up between 0 and 3 years of age. Mixed logistic regression models were used to test for associations. RESULTS Children with BPD attending daycare were more likely to have emergency department visits and systemic steroid usage. Children in daycare up to 3 years of age also were more likely to report trouble breathing, having activity limitations, and using rescue medications when compared with children not in daycare. More severe manifestations were found in children attending daycare between 6 and 12 months of chronological age. CONCLUSIONS In this study, children born preterm with BPD who attend daycare were more likely to visit the emergency department, use systemic steroids, and have chronic respiratory symptoms compared with children not in daycare, indicating that daycare may be a potential modifiable risk factor to minimize respiratory morbidities in children with BPD during the preschool years.
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Affiliation(s)
- Sharon A McGrath-Morrow
- Division of Pulmonary and Sleep Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA.
| | - Amit Agarwal
- Division of Pediatric Pulmonary and Sleep Medicine, Arkansas Children's Hospital, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Stamatia Alexiou
- Division of Pulmonary and Sleep Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA
| | - Eric D Austin
- Pulmonary Medicine, Vanderbilt University and Vanderbilt University Medical Center, Nashville, TN
| | - Julie L Fierro
- Division of Pulmonary and Sleep Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA
| | - Lystra P Hayden
- Division of Pulmonary Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA
| | - Khanh Lai
- Division of Pediatric Pulmonary and Sleep Medicine, University of Utah, Salt Lake City, UT
| | - Jonathan C Levin
- Division of Pulmonary Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA
| | | | - Paul E Moore
- Pulmonary Medicine, Vanderbilt University and Vanderbilt University Medical Center, Nashville, TN
| | - Lawrence M Rhein
- Neonatal-Perinatal Medicine/Pediatric Pulmonology, University of Massachusetts, Worcester, MA
| | - Jessica L Rice
- Division of Pulmonary and Sleep Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA
| | - Catherine A Sheils
- Division of Pulmonary Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA
| | - Michael C Tracy
- Division of Pediatric Pulmonary, Stanford University, Stanford, CA
| | - Manvi Bansal
- Pulmonology and Sleep Medicine, Children's Hospital of Los Angeles, Los Angeles, CA
| | - Christopher D Baker
- Section of Pulmonary and Sleep Medicine, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO
| | - A Ioana Cristea
- Division of Pediatric Pulmonology, Allergy and Sleep Medicine, Riley Children's Hospital and Indiana University, Indianapolis, IN
| | | | | | - Natalie Villafranco
- Pulmonary Medicine, Texas Children's Hospital and Baylor University, Houston, TX
| | - Leif D Nelin
- Division of Neonatology, Nationwide Children's Hospital and Ohio State University, Columbus, OH
| | - Joseph M Collaco
- Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins University, Baltimore, MD
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Levin JC, Cavanaugh C, Malpocher K, Leeman KT. Tracheostomy in a Preterm Infant with Severe Bronchopulmonary Dysplasia. Neoreviews 2022; 23:e708-e715. [PMID: 36180733 DOI: 10.1542/neo.23-10-e708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Jonathan C Levin
- Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, MA.,Division of Pulmonary Medicine, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Christina Cavanaugh
- Division of Pulmonary Medicine, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Kathryn Malpocher
- Division of Pulmonary Medicine, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Kristen T Leeman
- Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, MA
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Lewis TR, Kielt MJ, Walker VP, Levin JC, Guaman MC, Panitch HB, Nelin LD, Abman SH. Association of Racial Disparities With In-Hospital Outcomes in Severe Bronchopulmonary Dysplasia. JAMA Pediatr 2022; 176:852-859. [PMID: 35913704 PMCID: PMC9344383 DOI: 10.1001/jamapediatrics.2022.2663] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Bronchopulmonary dysplasia (BPD) is the most common serious morbidity of preterm birth. Short-term respiratory outcomes for infants with the most severe forms of BPD are highly variable. The mechanisms that explain this variability remain unknown and may be mediated by racial disparities. OBJECTIVE To determine the association of maternal race with death and length of hospital stay in a multicenter cohort of infants with severe BPD. DESIGN, SETTING, AND PARTICIPANTS This multicenter cohort study included preterm infants enrolled in the BPD Collaborative registry from January 1, 2015, to July 19, 2021, involving 8 BPD Collaborative centers located in the US. Included patients were born at less than 32 weeks' gestation, had a diagnosis of severe BPD as defined by the 2001 National Institutes of Health Consensus Criteria, and were born to Black or White mothers. EXPOSURES Maternal race: Black vs White. MAIN OUTCOMES AND MEASURES Death and length of hospital stay. RESULTS Among 834 registry infants (median [IQR] gestational age, 25 [24-27] weeks; 492 male infants [59%]) meeting inclusion criteria, the majority were born to White mothers (558 [67%]). Death was observed infrequently in the study cohort (32 [4%]), but Black maternal race was associated with an increased odds of death (adjusted odds ratio, 2.1; 95% CI, 1.2-3.5) after adjusting for center. Black maternal race was also significantly associated with length of hospital stay (adjusted between-group difference, 10 days; 95% CI, 3-17 days). CONCLUSIONS AND RELEVANCE In a multicenter severe BPD cohort, study results suggest that infants born to Black mothers had increased likelihood of death and increased length of hospital stay compared with infants born to White mothers. Prospective studies are needed to define the sociodemographic mechanisms underlying disparate health outcomes for Black infants with severe BPD.
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Affiliation(s)
- Tamorah R. Lewis
- Children’s Mercy Hospital, The University of Missouri—Kansas City, Kansas City
| | - Matthew J. Kielt
- Nationwide Children’s Hospital, The Ohio State University College of Medicine, Columbus
| | - Valencia P. Walker
- Nationwide Children’s Hospital, The Ohio State University College of Medicine, Columbus
| | - Jonathan C. Levin
- Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts
| | | | - Howard B. Panitch
- Children’s Hospital of Philadelphia, Perelman School of Medicine at The University of Pennsylvania, Philadelphia
| | - Leif D. Nelin
- Nationwide Children’s Hospital, The Ohio State University College of Medicine, Columbus
| | - Steven H. Abman
- Children's Hospital Colorado, The University of Colorado School of Medicine, Aurora
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15
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Collaco JM, Tracy MC, Sheils CA, Rice JL, Rhein LM, Nelin LD, Moore PE, Manimtim WM, Levin JC, Lai K, Hayden LP, Fierro JL, Austin ED, Alexiou S, Agarwal A, Villafranco N, Siddaiah R, Popova AP, Cristea IA, Baker CD, Bansal M, McGrath-Morrow SA. Insurance coverage and respiratory morbidities in bronchopulmonary dysplasia. Pediatr Pulmonol 2022; 57:1735-1743. [PMID: 35437911 PMCID: PMC9232996 DOI: 10.1002/ppul.25933] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 04/07/2022] [Accepted: 04/17/2022] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Preterm infants and young children with bronchopulmonary dysplasia (BPD) are at increased risk for acute care utilization and chronic respiratory symptoms during early life. Identifying risk factors for respiratory morbidities in the outpatient setting could decrease the burden of care. We hypothesized that public insurance coverage was associated with higher acute care usage and respiratory symptoms in preterm infants and children with BPD after initial neonatal intensive care unit (NICU) discharge. METHODS Subjects were recruited from BPD clinics at 10 tertiary care centers in the United States between 2018 and 2021. Demographics and clinical characteristics were obtained through chart review. Surveys for clinical outcomes were administered to caregivers. RESULTS Of the 470 subjects included in this study, 249 (53.0%) received employer-based insurance coverage and 221 (47.0%) received Medicaid as sole coverage at least once between 0 and 3 years of age. The Medicaid group was twice as likely to have sick visits (adjusted odd ratio [OR]: 2.06; p = 0.009) and emergency department visits (aOR: 2.09; p = 0.028), and three times more likely to be admitted for respiratory reasons (aOR: 3.04; p = 0.001) than those in the employer-based group. Additionally, those in the Medicaid group were more likely to have nighttime respiratory symptoms (aOR: 2.62; p = 0.004). CONCLUSIONS Children with BPD who received Medicaid coverage were more likely to utilize acute care and have nighttime respiratory symptoms during the first 3 years of life. More comprehensive studies are needed to determine whether the use of Medicaid represents a barrier to accessing care, lower socioeconomic status, and/or a proxy for detrimental environmental exposures.
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Affiliation(s)
- Joseph M Collaco
- Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins University, Baltimore, Maryland, USA
| | - Michael C Tracy
- Division of Pediatric Pulmonary, Stanford University, Stanford, California, USA
| | - Catherine A Sheils
- Division of Pulmonary Medicine, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Jessica L Rice
- Division of Pulmonary Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Lawrence M Rhein
- Neonatal-Perinatal Medicine/Pediatric Pulmonology, University of Massachusetts, Worcester, Massachusetts, USA
| | - Leif D Nelin
- Division of Neonatology, Nationwide Children's Hospital and Ohio State University, Columbus, Ohio, USA
| | - Paul E Moore
- Pulmonary Medicine, Vanderbilt University and Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Winston M Manimtim
- Neonatal/Perinatal Medicine, Children's Mercy Hospital, Kansas City, Missouri, USA
| | - Jonathan C Levin
- Division of Pulmonary Medicine, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Khanh Lai
- Division of Pediatric Pulmonary and Sleep Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Lystra P Hayden
- Division of Pulmonary Medicine, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Julie L Fierro
- Division of Pulmonary Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Eric D Austin
- Pulmonary Medicine, Vanderbilt University and Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Stamatia Alexiou
- Division of Pulmonary Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Amit Agarwal
- Division of Pulmonary Medicine, Arkansas Children's Hospital and University of Arkansas for medical Sciences, Little Rock AR, Pennsylvania, USA
| | - Natalie Villafranco
- Pulmonary Medicine, Texas Children's Hospital and Baylor University, Houston, Texas, USA
| | - Roopa Siddaiah
- Pediatric Pulmonology, Penn State Health, Hershey, Pennsylvania, USA
| | - Antonia P Popova
- Pediatric Pulmonology, University of Michigan, Ann Arbor, Michigan, USA
| | - Ioana A Cristea
- Division of Pediatric Pulmonology, Allergy and Sleep Medicine, Riley Children's Hospital and Indiana University, Indianapolis, Indiana, USA
| | - Christopher D Baker
- Section of Pulmonary and Sleep Medicine, Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Manvi Bansal
- Pulmonology and Sleep Medicine, Children's Hospital of Los Angeles, Los Angeles, California, USA
| | - Sharon A McGrath-Morrow
- Division of Pulmonary Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania, USA
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16
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Cristea AI, Ren CL, Amin R, Eldredge LC, Levin JC, Majmudar PP, May AE, Rose RS, Tracy MC, Watters KF, Allen J, Austin ED, Cataletto ME, Collaco JM, Fleck RJ, Gelfand A, Hayes D, Jones MH, Kun SS, Mandell EW, McGrath-Morrow SA, Panitch HB, Popatia R, Rhein LM, Teper A, Woods JC, Iyer N, Baker CD. Outpatient Respiratory Management of Infants, Children, and Adolescents with Post-Prematurity Respiratory Disease: An Official American Thoracic Society Clinical Practice Guideline. Am J Respir Crit Care Med 2021; 204:e115-e133. [PMID: 34908518 PMCID: PMC8865713 DOI: 10.1164/rccm.202110-2269st] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background: Premature birth affects millions of neonates each year, placing them at risk for respiratory disease due to prematurity. Bronchopulmonary dysplasia is the most common chronic lung disease of infancy, but recent data suggest that even premature infants who do not meet the strict definition of bronchopulmonary dysplasia can develop adverse pulmonary outcomes later in life. This post-prematurity respiratory disease (PPRD) manifests as chronic respiratory symptoms, including cough, recurrent wheezing, exercise limitation, and reduced pulmonary function. This document provides an evidence-based clinical practice guideline on the outpatient management of infants, children, and adolescents with PPRD. Methods: A multidisciplinary panel of experts posed questions regarding the outpatient management of PPRD. We conducted a systematic review of the relevant literature. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to rate the quality of evidence and the strength of the clinical recommendations. Results: The panel members considered the strength of each recommendation and evaluated the benefits and risks of applying the intervention. In formulating the recommendations, the panel considered patient and caregiver values, the cost of care, and feasibility. Recommendations were developed for or against three common medical therapies and four diagnostic evaluations in the context of the outpatient management of PPRD. Conclusions: The panel developed recommendations for the outpatient management of patients with PPRD on the basis of limited evidence and expert opinion. Important areas for future research were identified.
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Levin JC, Beam AL, Fox KP, Mandl KD. Medication utilization in children born preterm in the first two years of life. J Perinatol 2021; 41:1732-1738. [PMID: 33547407 PMCID: PMC8277664 DOI: 10.1038/s41372-021-00930-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 10/12/2020] [Accepted: 01/15/2021] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To compare medications dispensed during the first 2 years in children born preterm and full-term. STUDY DESIGN Retrospective analysis of claims data from a commercial national managed care plan 2008-2019. 329,855 beneficiaries were enrolled from birth through 2 years, of which 25,408 (7.7%) were preterm (<37 weeks). Filled prescription claims and paid amount over 2 years were identified. RESULTS In preterm children, the number of filled prescriptions was 1.4 times and cost was 3.8 times that of full-term children. Number and cost of medications were inversely related to gestational age. Differences peak at 4-9 months and resolve by 19 months after discharge. Palivizumab, ranitidine, albuterol, lansoprazole, budesonide, and prednisolone had the greatest differences in utilization. CONCLUSION Prescription medication utilization among preterm children under 2 years is driven by palivizumab, anti-reflux, and respiratory medications, despite little evidence regarding efficacy for many medications and concern for harm with certain classes.
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Affiliation(s)
- Jonathan C Levin
- Computational Health Informatics Program, Boston Children's Hospital, Boston, MA, USA.
- Division of Newborn Medicine, Boston Children's Hospital, Boston, MA, USA.
- Division of Pulmonary Medicine, Boston Children's Hospital, Boston, MA, USA.
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA.
| | - Andrew L Beam
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Kathe P Fox
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Kenneth D Mandl
- Computational Health Informatics Program, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
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18
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Levin JC, Sheils CA, Gaffin JM, Hersh CP, Rhein LM, Hayden LP. Lung function trajectories in children with post-prematurity respiratory disease: identifying risk factors for abnormal growth. Respir Res 2021; 22:143. [PMID: 33971884 PMCID: PMC8112031 DOI: 10.1186/s12931-021-01720-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 04/14/2021] [Indexed: 11/13/2022] Open
Abstract
Background Survivors of prematurity are at risk for abnormal childhood lung function. Few studies have addressed trajectories of lung function and risk factors for abnormal growth in childhood. This study aims to describe changes in lung function in a contemporary cohort of children born preterm followed longitudinally in pulmonary clinic for post-prematurity respiratory disease and to assess maternal and neonatal risk factors associated with decreased lung function trajectories. Methods Observational cohort of 164 children born preterm ≤ 32 weeks gestation followed in pulmonary clinic at Boston Children’s Hospital with pulmonary function testing. We collected demographics and neonatal history. We used multivariable linear regression to identify the impact of neonatal and maternal risk factors on lung function trajectories in childhood. Results We identified 264 studies from 82 subjects with acceptable longitudinal FEV1 data and 138 studies from 47 subjects with acceptable longitudinal FVC and FEV1/FVC data. FEV1% predicted and FEV1/FVC were reduced compared to childhood norms. Growth in FVC outpaced FEV1, resulting in an FEV1/FVC that declined over time. In multivariable analyses, longer duration of mechanical ventilation was associated with a lower rate of rise in FEV1% predicted and greater decline in FEV1/FVC, and postnatal steroid exposure in the NICU was associated with a lower rate of rise in FEV1 and FVC % predicted. Maternal atopy and asthma were associated with a lower rate of rise in FEV1% predicted. Conclusions Children with post-prematurity respiratory disease demonstrate worsening obstruction in lung function throughout childhood. Neonatal risk factors including exposure to mechanical ventilation and postnatal steroids, as well as maternal atopy and asthma, were associated with diminished rate of rise in lung function. These results may have implications for lung function trajectories into adulthood. Supplementary Information The online version contains supplementary material available at 10.1186/s12931-021-01720-0.
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Affiliation(s)
- Jonathan C Levin
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Ave Hunnewell 4, Boston, MA, 02115, USA. .,Division of Pulmonary Medicine, Boston Children's Hospital, Boston, MA, USA.
| | - Catherine A Sheils
- Division of Pulmonary Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Jonathan M Gaffin
- Division of Pulmonary Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Craig P Hersh
- Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Lawrence M Rhein
- Department of Pediatrics, University of Massachusetts, Worcester, MA, USA
| | - Lystra P Hayden
- Division of Pulmonary Medicine, Boston Children's Hospital, Boston, MA, USA.,Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, MA, USA
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19
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Niccum M, Spyropoulos F, Levin JC, Petty CR, Mullen MP, Christou H. Lower oxygen saturation targets in preterm infants are not associated with increased rates of pulmonary hypertension. J Neonatal Perinatal Med 2021; 14:519-526. [PMID: 33720854 DOI: 10.3233/npm-200637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The optimal oxygen saturation target in preterm infants is not known. In this study, we aimed to assess the effect of lower oxygen saturation targets on the rate of bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), and pulmonary hypertension (PH) in preterm infants. METHODS Retrospective cohort study comparing BPD, ROP, and PH incidence among two cohorts of infants born at≤32 weeks gestation with different oxygen saturation targets at≥34 weeks post-menstrual age (PMA): cohort 1, 94-98% (n = 126); cohort 2, 92-97% (n = 121). Groups compared by Chi-square test, t-test, and multivariable logistic regression. RESULTS When comparing cohort 1 (average gestational age 29.8 weeks, average birth weight 1271g) with cohort 2 (average gestational age 29.6 weeks, average birth weight 1299g), there was no difference in rate of BPD (24% vs. 19%, p = 0.38), ROP (4% vs. 3%, p = 0.49), or PH (2% vs. 4%, p = 0.44). CONCLUSION An oxygen saturation target of 92-97% at≥34 weeks PMA was not associated with a higher rate of PH or lower rate of BPD or ROP when compared with a higher target of 94-98%.
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Affiliation(s)
- M Niccum
- Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
| | - F Spyropoulos
- Department of Pediatric Newborn Medicine, Brigham and Women's Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
| | - J C Levin
- Department of Pediatrics, Division of Newborn Medicine, Boston, MA, USA.,Division of Pulmonary Medicine, Boston Children's Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
| | - C R Petty
- Institutional Centers for Clinical and Translational Research, Boston Children's Hospital, Boston, MA, USA
| | - M P Mullen
- Department of Cardiology, Boston Children's Hospital, Department of Pediatrics, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
| | - H Christou
- Department of Pediatric Newborn Medicine, Brigham and Women's Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
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Annesi CA, Levin JC, Litt JS, Sheils CA, Hayden LP. Long-term respiratory and developmental outcomes in children with bronchopulmonary dysplasia and history of tracheostomy. J Perinatol 2021; 41:2645-2650. [PMID: 34290373 PMCID: PMC8294252 DOI: 10.1038/s41372-021-01144-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 06/20/2021] [Accepted: 06/30/2021] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The long-term morbidity among children with severe bronchopulmonary dysplasia who require tracheostomy (tBPD) relative to those without tracheostomy (sBPD) is not well characterized. We compared childhood lung function and neurodevelopmental outcomes in tBPD and sBPD. STUDY DESIGN Retrospective case-control study of N = 49 tBPD and N = 280 sBPD subjects in Boston Children's Hospital Preterm Lung Patient Registry and medical record. We compared NICU course, childhood spirometry, and neurodevelopmental testing. RESULT tBPD subjects were more likely than sBPD to be Black, have pulmonary hypertension, and have subglottic stenosis. tBPD subjects had lower maximal childhood FEV1 % predicted (β = -0.14) and FEV1/FVC (β = -0.08); spirometry curves were more likely to suggest fixed extrathoracic obstruction. tBPD subjects had greater cognitive and motor delays <24 months, and greater cognitive delays >24 months. CONCLUSION Compared to subjects with sBPD who did not require tracheostomy, tBPD subjects suffer from increased long-term impairment in respiratory function and neurodevelopment.
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Affiliation(s)
- Chandler A. Annesi
- grid.189504.10000 0004 1936 7558Boston University School of Medicine, Boston, MA USA
| | - Jonathan C. Levin
- grid.2515.30000 0004 0378 8438Division of Pulmonary Medicine, Boston Children’s Hospital, Boston, MA USA ,grid.2515.30000 0004 0378 8438Division of Newborn Medicine, Boston Children’s Hospital, Boston, MA USA ,grid.38142.3c000000041936754XDepartment of Pediatrics, Harvard Medical School, Boston, MA USA
| | - Jonathan S. Litt
- grid.2515.30000 0004 0378 8438Division of Newborn Medicine, Boston Children’s Hospital, Boston, MA USA ,grid.38142.3c000000041936754XDepartment of Pediatrics, Harvard Medical School, Boston, MA USA
| | - Catherine A. Sheils
- grid.2515.30000 0004 0378 8438Division of Pulmonary Medicine, Boston Children’s Hospital, Boston, MA USA ,grid.38142.3c000000041936754XDepartment of Pediatrics, Harvard Medical School, Boston, MA USA
| | - Lystra P. Hayden
- grid.2515.30000 0004 0378 8438Division of Pulmonary Medicine, Boston Children’s Hospital, Boston, MA USA ,grid.38142.3c000000041936754XDepartment of Pediatrics, Harvard Medical School, Boston, MA USA ,grid.62560.370000 0004 0378 8294Channing Division of Network Medicine, Brigham and Women’s Hospital, Boston, MA USA
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Abstract
BACKGROUND The Accreditation Council for Graduate Medical Education has called for increased emphasis on reporting objective performance measures to trainees and programs. However, reporting of objective measures, including clinical volume, is largely omitted from training programs. OBJECTIVE To use automated electronic medical systems at a tertiary pediatric care hospital to create a dashboard that reports objective trainee and program metrics, including clinical volume and diagnoses in a pediatrics residency. METHODS We queried an enterprise data warehouse that aggregates data daily from multiple hospital systems to identify patient encounters during which senior pediatrics residents at Boston Children's Hospital had entered documentation over a 9-month period. From this query, we created a filterable dashboard to display clinical volume and diagnosis data by individual resident and in aggregate. RESULTS A total of 44 of 45 senior residents (98%) in the program were included in analysis. We identified 12 198 patient encounters during which a senior pediatrics resident had entered documentation; these included a median of 332 inpatient encounters per resident, 122 emergency department encounters, and 84 outpatient encounters. The most common diagnoses stratified by clinical site were: inpatient - dehydration (median = 61); emergency department - long-term/current drug therapy (median = 16); and outpatient - encounter for immunization (median = 48). CONCLUSIONS We used electronic health record systems to generate performance dashboards for trainees in a pediatrics residency across different sites of care with reported volume by diagnosis. Our dashboards provide feedback to program leadership regarding individual and aggregate trainee experience and allow individual trainees to compare their clinical exposure to peers.
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Levin JC, Jang J, Rhein LM. Apnea in the Otherwise Healthy, Term Newborn: National Prevalence and Utilization during the Birth Hospitalization. J Pediatr 2017; 181:67-73.e1. [PMID: 27865430 DOI: 10.1016/j.jpeds.2016.10.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 09/15/2016] [Accepted: 10/07/2016] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To describe the prevalence of apnea in otherwise healthy term newborns, identify attributable length of stay (LOS) and healthcare utilization (cost) of apnea, and measure hospital variation in attributable LOS and cost of apnea in this population. STUDY DESIGN We conducted a secondary analysis of a national administrative dataset, the 2012 Kids' Inpatient Database, which included 3.4 million newborn discharges in the US. The birth hospitalizations of approximately 2.6 million otherwise healthy, full-term newborns were included for analysis. Attributable LOS and cost of apnea were calculated using multivariate analyses. RESULTS Apnea was diagnosed in 1 in 1000 healthy full-term newborns. Multivariate analyses showed that newborns with apnea had 0.6 days longer LOS (P < .001) and $483 greater costs (P < .001) compared with healthy term newborns, per birth hospitalization. Newborns diagnosed with apnea plus hypoxia and/or bradycardia had 1.4 days longer LOS (P < .001) and $653 greater costs (P < .001). The attributable LOS and cost attributable to apnea varied between individual hospitals and differed by hospital region. CONCLUSIONS Apnea is associated with higher LOS and cost in the newborn hospitalization, with variation in hospital practice. This suggests the need for better comprehension of the underlying physiology and standardization of practice in its management in the term newborn.
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Affiliation(s)
| | - Jisun Jang
- Clinical Research Center, Boston Children's Hospital, Boston, MA
| | - Lawrence M Rhein
- Division of Neonatology, University of Massachusetts Memorial Medical Center, Worcester, MA; Division of Pulmonary and Allergy, University of Massachusetts Memorial Medical Center, Worcester, MA
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Levin JC, Gagnon L, He X, Baum ED, Karas DE, Chupp GL. Improvement in asthma control and inflammation in children undergoing adenotonsillectomy. Pediatr Res 2014; 75:403-8. [PMID: 24452590 PMCID: PMC3943680 DOI: 10.1038/pr.2013.237] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 08/15/2013] [Indexed: 12/28/2022]
Abstract
BACKGROUND Observational studies suggest that asthma control improves after adenotonsillectomy, but longitudinal studies that correlate the effect of the procedure on the levels of biomarkers associated with airway inflammation are limited. METHODS We conducted a longitudinal, observational study on pediatric patients, both with and without asthma, undergoing adenotonsillectomy. Asthma control test (ACT) scores and chitinase activity in the circulation were measured at time of surgery and at 6-mo follow-up. RESULTS Sixty-six children with asthma and 64 control subjects were enrolled. Mean ACT scores improved by three points (P < 0.001) after 6 mo. 85% of children with poorly controlled asthma demonstrated an increase in ACT score of at least three points or a decrease in emergency department/urgent care visits, oral corticosteroid courses, or rescue short acting bronchodilator usage. Chitinase activity decreased significantly in asthmatics who improved (P < 0.01). Higher chitinase activity levels at baseline were associated with improved asthma control following surgery (P < 0.01). CONCLUSION In children with high preoperative circulating chitinase activity levels, asthma control and healthcare utilization were significantly improved after adenotonsillecotmy. Chitinase activity decreased after surgery in children with improved control. This suggests that adenotonsillectomy modulates chitinase activity, affecting airway inflammation and improving airway disease.
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Affiliation(s)
- Jonathan C Levin
- Section of Pulmonary and Critical Care, Yale University School of Medicine, New Haven, CT
| | - Lisa Gagnon
- Section of Otolaryngology, Yale University School of Medicine, New Haven, CT
| | - Xiaoxuan He
- Section of Pulmonary and Critical Care, Yale University School of Medicine, New Haven, CT
| | - Eric D Baum
- Section of Otolaryngology, Yale University School of Medicine, New Haven, CT
| | - David E Karas
- Section of Otolaryngology, Yale University School of Medicine, New Haven, CT
| | - Geoffrey L Chupp
- Section of Pulmonary and Critical Care, Yale University School of Medicine, New Haven, CT
,Address correspondence to: Geoffrey L Chupp, MD, Pulmonary, Critical Care and Sleep Medicine, PO Box 208057, 300 Cedar Street, New Haven, CT 06520-8057, Phone: (203) 785-3627, Fax: (203) 785-3826
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Morad SAF, Levin JC, Tan SF, Fox TE, Feith DJ, Cabot MC. Novel off-target effect of tamoxifen--inhibition of acid ceramidase activity in cancer cells. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:1657-64. [PMID: 23939396 DOI: 10.1016/j.bbalip.2013.07.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 07/18/2013] [Accepted: 07/30/2013] [Indexed: 10/26/2022]
Abstract
Acid ceramidase (AC), EC 3.5.1.23, a lysosomal enzyme, catalyzes the hydrolysis of ceramide to constituent sphingoid base, sphingosine, and fatty acid. Because AC regulates the levels of pro-apoptotic ceramide and mitogenic sphingosine-1-phosphate, it is considered an apt target in cancer therapy. The present study reveals, for the first time, that the prominent antiestrogen, tamoxifen, is a pan-effective AC inhibitor in the low, single digit micromolar range, as demonstrated in a wide spectrum of cancer cell types, prostate, pancreatic, colorectal, and breast. Prostate cancer cells were chosen for the detailed investigations. Treatment of intact PC-3 cells with tamoxifen produced time- and dose-dependent inhibition of AC activity. Tamoxifen did not impact cell viability nor did it inhibit AC activity in cell-free assays. In pursuit of mechanism of action, we demonstrate that tamoxifen induced time-, as early as 5min, and dose-dependent, as low as 5μM, increases in lysosomal membrane permeability (LMP), and time- and dose-dependent downregulation of AC protein expression. Assessing various protease inhibitors revealed that a cathepsin B inhibitor blocked tamoxifen-elicited downregulation of AC protein; however, this action failed to restore AC activity unless assayed in a cell-free system at pH4.5. In addition, pretreatment with tamoxifen inhibited PC-3 cell migration. Toremifene, an antiestrogen structurally similar to tamoxifen, was also a potent inhibitor of AC activity. This study reveals a new, off-target action of tamoxifen that may be of benefit to enhance anticancer therapies that either incorporate ceramide or target ceramide metabolism.
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Affiliation(s)
- Samy A F Morad
- John Wayne Cancer Institute at Saint John's Health Center, Department of Experimental Therapeutics, Santa Monica, CA 90404, USA
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Morad SA, Levin JC, Abdelmageed N, Kester M, Shanmugavdlandy SS, Paulson RF, Rosenberg DW, Madigan JP, Cabot MC. Abstract 2027: Tamoxifen amplifies antitumor impact of nanoformulated ceramide- pan efficacy in a myriad of tumor cell types. Cancer Res 2013. [DOI: 10.1158/1538-7445.am2013-2027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Although ceramide has potent tumor suppressor properties, its use in cancer therapeutics has been limited; this is mainly due to rapid metabolism of ceramide by cancer cells, the inability to attain therapeutic levels when ceramide-generating agents are employed, and the inherent insolubility of ceramide as a therapeutic. Our approach circumvents these disadvantages and provides advantages over existing methodologies. For example, rather than promoting intracellular ceramide generation by application of exogenous drugs that activate de novo and sphingomyelinase pathways, we have chosen to administer ceramide exogenously in the form of short-chain C6-ceramide nanoliposomes; this overcomes solubility issues and improves uptake. In addition, nanoliposomes are efficient platforms for delivering other hydrophobic chemotherapeutics. The antiestrogen tamoxifen was selected for our studies because of its unusual “off-target” actions, which include inhibition of ceramide metabolism at glycosylation and hydrolysis. Blocking these junctures increases C6-ceramide intracellular residence time and diminishes production of sphingosine 1-phosphate, a mitogenic lipid derived via the action of ceramidase and sphingosine kinase. Hence, C6-ceramide and tamoxifen make up a versatile drug duo. Using in vitro models of human colon and breast cancer, acute mylogenous leukemia (AML), and melanoma, we show that simultaneous administration of nanoliposomal C6-ceramide and tamoxifen potently and synergistically decreased cell viability, compared to the single agents. The mix induced caspase-dependent apoptosis, cell cycle arrest at G1 and G2, upregulation of JNK, p38, and p53, and downregulation of Akt and survivin. In triple negative, hormone-insensitive breast cancer cells, C6-ceramide-tamoxifen induced cell cycle arrest, caspase-dependent apoptosis, and lysosomal and mitochondrial membrane permeability. Evaluation of single agents showed that tamoxifen elicited lysosomal membrane permeability and inhibited acid ceramidase. We have obtained similar results in in vitro models of human melanoma and AML. In an in vivo retroviral transduced murine AML model, the combination lowered leukemia burden in spleen and marrow. The combination also perpetuated synergistic increases in long-chain ceramides, likely compounding the overall ceramide effect. Of interest regarding in vivo utility, the major metabolites of tamoxifen, N-desmethyltamoxifen and 4-hydroxytamoxifen, were effective in combination with C6-ceramide. Our findings show that tamoxifen magnifies the antiproliferative effects of C6-ceramide via aggregate mechanisms. This proficient, ceramide-based nanoliposomal drug regimen may have potential as an effective anticancer therapeutic.
Supported by NIGMS 77391; ABC's, Los Angeles; Fashion Footwear Association of New York Charitable Foundation.
Citation Format: Samy A.F. Morad, Jonathan C. Levin, Noha Abdelmageed, Mark Kester, Sriram S. Shanmugavdlandy, Robert F. Paulson, Daniel W. Rosenberg, James P. Madigan, Myles C. Cabot. Tamoxifen amplifies antitumor impact of nanoformulated ceramide- pan efficacy in a myriad of tumor cell types. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2027. doi:10.1158/1538-7445.AM2013-2027
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Morad SAF, Madigan JP, Levin JC, Abdelmageed N, Karimi R, Rosenberg DW, Kester M, Shanmugavelandy SS, Cabot MC. Tamoxifen magnifies therapeutic impact of ceramide in human colorectal cancer cells independent of p53. Biochem Pharmacol 2013; 85:1057-65. [PMID: 23353700 DOI: 10.1016/j.bcp.2013.01.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 01/16/2013] [Accepted: 01/18/2013] [Indexed: 12/28/2022]
Abstract
Poor prognosis in patients with later stage colorectal cancer (CRC) necessitates the search for new treatment strategies. Ceramide, because of its role in orchestrating death cascades in cancer cells, is a versatile alternative. Ceramide can be generated by exposure to chemotherapy or ionizing radiation, or it can be administered in the form of short-chain analogs (C6-ceramide). Because intracellular P-glycoprotein (P-gp) plays a role in catalyzing the conversion of ceramide to higher sphingolipids, we hypothesized that administration of P-gp antagonists with C6-ceramide would magnify cell death cascades. Human CRC cell lines were employed, HCT-15, HT-29, and LoVo. The addition of either tamoxifen, VX-710, verapamil, or cyclosporin A, antagonists of P-gp, enhanced C6-ceramide cytotoxicity in all cell lines. In depth studies with C6-ceramide and tamoxifen in LoVo cells showed the regimen induced PARP cleavage, caspase-dependent apoptosis, mitochondrial membrane permeabilization (MMP), and cell cycle arrest at G1 and G2. At the molecular level, the regimen, but not single agents, induced time-dependent upregulation of tumor suppressor protein p53; however, introduction of a p53 inhibitor staved neither MMP nor apoptosis. Nanoliposomal formulations of C6-ceramide and tamoxifen were also effective, yielding synergistic cell kill. We conclude that tamoxifen is a favorable adjuvant for enhancing C6-ceramide cytotoxicity in CRC, and demonstrates uniquely integrated effects. The high frequency of expression of P-gp in CRC presents an adventitious target for complementing ceramide-based therapies, a strategy that could hold promise for treatment of resistant disease.
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Affiliation(s)
- Samy A F Morad
- John Wayne Cancer Institute, Santa Monica, CA 90404, USA
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Morad SAF, Messner MC, Levin JC, Abdelmageed N, Park H, Merrill AH, Cabot MC. Potential role of acid ceramidase in conversion of cytostatic to cytotoxic end-point in pancreatic cancer cells. Cancer Chemother Pharmacol 2012; 71:635-45. [PMID: 23263160 DOI: 10.1007/s00280-012-2050-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 12/04/2012] [Indexed: 12/29/2022]
Abstract
PURPOSE Acid ceramidase (AC) occupies an important place in the control of cancer cell proliferation. We tested the influence of AC inhibition on the effects of PSC 833, a P-glycoprotein antagonist with potent ceramide-generating capacity, to determine whether AC could be a therapeutic target in pancreatic cancer. METHODS Ceramide metabolism was followed using (3)H-palmitate, and molecular species were determined by mass spectroscopy. Apoptosis was measured by DNA fragmentation, autophagy by acridine orange staining, and cell cycle was assessed by flow cytometry and RB phosphorylation. AC was measured in intact cells using fluorescent substrate. RESULTS Exposure of human PANC-1 or MIA-PaCa-2 cells to PSC 833 promoted increases in de novo (dihydro)ceramides, (dihydro)glucosylceramides, and (dihydro)sphingomyelins, demarking ceramide generation and robust metabolism. Despite the multifold increases in (dihydro)ceramide levels, cells were refractory to PSC 833. However, PSC 833 produced a dose-dependent decrease in DNA synthesis and dose- and time-dependent decreases in RB phosphorylation, consistent with cell cycle arrest as demonstrated at G1. Cytostatic effects of PSC 833 were converted to cytotoxic end-point by acid ceramidase inhibition. Cytotoxicity was accompanied by formation of acridine orange-stained acidic vesicles and an increase in LC3 expression, indicative of autophagic response. Cell death was not reversed by preexposure to myriocin, which blocks PSC 833-induced ceramide generation. CONCLUSION Although the role of ceramide in end-point cytotoxicity is unclear, our results suggest that acid ceramidase is a viable target in pancreatic cancer. We propose that AC inhibition will be effective in concert with other anticancer therapies.
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Affiliation(s)
- Samy A F Morad
- Department of Experimental Therapeutics, John Wayne Cancer Institute, 2200 Santa Monica Blvd, Santa Monica, CA 90404, USA
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Morad SAF, Levin JC, Shanmugavelandy SS, Kester M, Fabrias G, Bedia C, Cabot MC. Ceramide--antiestrogen nanoliposomal combinations--novel impact of hormonal therapy in hormone-insensitive breast cancer. Mol Cancer Ther 2012; 11:2352-61. [PMID: 22962326 DOI: 10.1158/1535-7163.mct-12-0594] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Although the sphingolipid ceramide exhibits potent tumor suppressor effects, efforts to harness this have been hampered by poor solubility, uptake, bioavailability, and metabolic conversion. Therefore, identification of avenues to improve efficacy is necessary for development of ceramide-based therapies. In this study, we used mutant p53, triple-negative breast cancer (TNBC) cells, a type of breast cancer highly refractory to treatment, and cell-permeable nanoliposomal C6-ceramide in conjunction with the antiestrogen tamoxifen, which has been shown to be an effective modulator of ceramide metabolism. We show for the first time that nanoliposomal tamoxifen enhances nanoliposomal C6-ceramide cytotoxicity in cultured TNBC cells, a response that was accompanied by induction of cell-cycle arrest at G(1) and G(2), caspase-dependent induction of DNA fragmentation, and enhanced mitochondrial and lysosomal membrane permeability at 18 and 2 hours, respectively. Tamoxifen metabolites were also effective. Only tamoxifen promoted lysosomal membrane permeability. In addition, we show for the first time that tamoxifen inhibits acid ceramidase, as measured in intact cell assays; this effect was irreversible. Together, our findings show that tamoxifen magnifies the antiproliferative effects of C6-ceramide via combined targeting of cell-cycle traverse and lysosomal and mitochondrial integrity. We adduce that C6-ceramide-induced apoptosis is amplified by tamoxifen's impact on lysosomes and perhaps accompanying inhibition of acid ceramidase, which could result in decreased levels of sphingosine 1-phosphate. This drug regimen could serve as a promising therapy for chemoresistant and triple-negative types of breast cancer, and thus represents an indication for tamoxifen, irrespective of estrogen receptor status.
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Affiliation(s)
- Samy A F Morad
- Department of Experimental Therapeutics, John Wayne Cancer Institute, 2200 Santa Monica Blvd, Santa Monica, CA 90404, USA
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Morad SA, Levin JC, Kester M, Shanmugavelandy SS, Cabot MC. Abstract 3833: Ceramide/tamoxifen nanoliposomal combination - A promising strategy for treatment of chemoresistant breast cancer. Cancer Res 2012. [DOI: 10.1158/1538-7445.am2012-3833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Drug resistance in breast and other cancers results from multiple gene interactions. Ceramide, a key intermediate in the sphingolipid pathway, can act as a powerful tumor suppressor. The employ of ceramide-based agents as opposed to the administration of ceramide generators such as daunorubicin, could be a smart strategy for cancer therapy. Polychemotherapy remains the best option for treatment of breast cancer at the aggressive, metastatic stage. The aim of our study was to investigate the cytotoxic and antiproliferative effects of ceramide (short-chain C6-ceramide) administered in combination with tamoxifen, used here as an inhibitor of ceramide glycosylation. We previously demonstrated the cytotoxicity of this combination in MDA-MB-231 cells; however, little regarding mechanism was established. The present study employs nanoliposomal formulations of both agents, a strategy to enhance efficacy. Four triple-negative chemoresistant breast cancer cell lines, MDA-MB-231, MDA-MB-468, BT-20 and Hs578T were used. Cytotoxicity assays revealed that C6-ceramide/tamoxifen synergistically reduced viability, compared to single agents in all four cell lines. For example, in MDA-MB-468 cells, nanoliposomal C6-ceramide (2.5 µM), tamoxifen (5 µM), and the combination reduced cell viability to 70, 85, and 10% of control, respectively (96 hr). A hallmark of cancer, implicated in tumor growth as well as metastasis, is resistance to induction of apoptosis. Assessment of cellular apoptosis showed that C6-ceramide/tamoxifen treatment promoted DNA fragmentation in a dose-dependant manner, attaining a value that was 36% over control at 24 hr. Introduction of the pan-caspase inhibitor, z-VAD-fmk, completely reversed DNA fragmentation, showing that apoptosis was mediated by caspase activation. The aggressive and metastatic behavior of any tumor is dependent on the ability of the cells to proliferate. Interestingly, the lower concentrations of our drug combination (2.5 µM) induced cell cycle arrest at G1, the first growth phase. In summary, this approach has potential to circumvent limitations of ceramide-based therapies, such as rapid ceramide clearance due to metabolism, the inability to attain therapeutic levels when ceramide-generating agents are employed, and inherent insolubility that is encountered. These findings demonstrate the in vitro efficacy of combination C6-ceramide/tamoxifen nanoliposomal formulations for suppressing growth of breast cancer cells, and suggest that tamoxifen may be an effective adjuvant for enhancing ceramide-driven cell death cascades. Supported by NIGMS 77391 and ABC's, Los Angeles.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3833. doi:1538-7445.AM2012-3833
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Affiliation(s)
| | | | - Mark Kester
- 2Penn State Milton S. Hershey Medical Center, Hershey, PA
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Abstract
Adaptive responses of bacteria that involve sensing the presence of other bacteria are often critical for proliferation and the expression of virulence characteristics. The autoinducer II (AI-2) pathway has recently been shown to be a mechanism for sensing other bacteria that is highly conserved among diverse bacterial species, including Gram-positive pathogens. However, a role for this pathway in the regulation of virulence factors in Gram-positive pathogens has yet to be established. In this study, we have inactivated luxS, an essential component of the AI-2 pathway, in the Gram-positive pathogen Streptococcus pyogenes. Analyses of the resulting mutants revealed the aberrant expression of several virulence properties that are regulated in response to growth phase, including enhanced haemolytic activity, and a dramatic reduction in the expression of secreted proteolytic activity. This latter defect was associated with a reduced ability to secrete and process the precursor of the cysteine protease (SpeB) as well as a difference in the timing of expression of the protease. Enhanced haemolytic activity of the luxS strain was also shown to be linked with an increased expression of the haemolysin S-associated gene sagA. Disruptions of luxS in these mutants also produced a media-dependent growth defect. Finally, an allelic replacement analysis of an S. pyogenes strain with a naturally occurring insertion of IS1239 in luxS suggested a mechanism for modulation of virulence during infection. Results from this study suggest that luxS makes an important contribution to the regulation of S. pyogenes virulence factors.
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Affiliation(s)
- W R Lyon
- Department of Molecular Microbiology, Washington University School of Medicine, Box 8230, St Louis, MO 63110-1093, USA
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Abstract
The hyaluronic acid capsule of group A Streptococcus (GAS) is an important virulence factor, but little is known about mechanisms that regulate capsule expression. Transposon Tn916 mutagenesis of the poorly encapsulated M-type 3 GAS strain DLS003 produced a transconjugant that exhibited a mucoid colony morphology, reflecting increased hyaluronic acid capsule production. Analysis of chromosomal DNA sequence immediately downstream of the transposon insertion identified two open reading frames, designated csrR and csrS, which exhibited sequence similarity to bacterial two-component regulatory systems. We constructed an in-frame deletion mutation within csrR, which encodes the putative response component. Replacement of the native csrR gene in the DLS003 chromosome with the mutant allele resulted in a sixfold increase in capsule production and a corresponding increase in transcription of the has operon, which contains the essential genes for hyaluronic acid synthesis. Increased capsule production by the csrR mutant strain was associated with enhanced resistance to complement-mediated opsonophagocytic killing in vitro and with a 500-fold increase in virulence in mice. These results establish CsrR as a negative regulator of hyaluronic acid capsule synthesis and suggest that it is part of a two-component regulatory system that influences capsule expression and virulence.
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Affiliation(s)
- J C Levin
- Channing Laboratory, Brigham and Women's Hospital, Boston, MA, USA
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Abstract
Neisseria gonorrhoeae WS1 is a spontaneous pyocin (a bacteriocin produced by Pseudomonas aeruginosa)-resistant mutant of N. gonorrhoeae FA19 that produces a truncated lipooligosaccharide (LOS) and is non-transformable. The LOS-specific mutation in WS1 was moved into a transformable background by transforming FA19 with chromosomal DNA from WS1 (generating strain JWS-1). A clone (pJCL2) capable of restoring JWS-1 to wild-type LOS expression, as detected by its acquisition of reactivity with monoclonal antibodies and by its complemented sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile, was isolated. Sequential unidirectional deletion and DNA sequence analysis of pJCL2 identified an open reading frame, designated lsi-7, that could complement the defect in JWS-1. Homology searches against various databases indicated that lsi-7 bad homology with several Escherichia coli genes involved in the phosphorylation of sugars. lsi-7 is adjacent to the lsi-6 gene, another gene involved in LOS biosynthesis. Complementation studies using Salmonella typhimurium lipopolysaccharide mutants showed lsi-6 and lsi-7 to be gonococcal homologs of S. typhimurium rfaD and rfaE, respectively. Reverse transcriptase PCR analysis demonstrated that lsi-6 and lsi-7 are part of the same transcriptional unit.
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Affiliation(s)
- J C Levin
- Department of Microbiology, University of Maryland, College Park, Maryland 20742, USA
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Wehlitz R, Hentges R, Prümper G, Farhat A, Buslaps T, Berrah N, Levin JC, Sellin IA, Becker U. Compton double-to-single ionization ratio of helium at 57 keV. Phys Rev A 1996; 53:R3720-R3722. [PMID: 9913451 DOI: 10.1103/physreva.53.r3720] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Levin JC, Armen GB, Sellin IA. Photoionization and Compton double ionization of helium from threshold to 20 keV. Phys Rev Lett 1996; 76:1220-1223. [PMID: 10061666 DOI: 10.1103/physrevlett.76.1220] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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35
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Armen GB, Levin JC, Sellin IA. Radiationless resonant Raman scattering interpretation of argon photoion yields measured in coincidence with K-LL Auger decay. Phys Rev A 1996; 53:772-784. [PMID: 9912949 DOI: 10.1103/physreva.53.772] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Abstract
Neisseria gonorrhoeae lipooligosaccharide (LOS) undergoes antigenic variation at a high rate, and this variation can be monitored by changes in a strain's ability to bind LOS-specific monoclonal antibodies. We report here the cloning and identification of a gene, lsi-2, that can mediate this variation. The DNA sequence of lsi-2 has been determined for N. gonorrhoeae 1291, a strain that expresses a high-molecular-mass LOS, and a derivative of this strain, RS132L, that produces a truncated LOS. In the parental strain, lsi-2 contains a string of 12 guanines in the middle of its coding sequence. In cells that had antigenically varied to produce a truncated LOS, the number of guanines in lsi-2 was altered. Site-specific deletions were constructed to verify that expression of a 3.6-kDa LOS is due to alterations in lsi-2.
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Affiliation(s)
- R J Danaher
- Department of Microbiology, University of Maryland, College Park 20742, USA
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Lucas CE, Hagman KE, Levin JC, Stein DC, Shafer WM. Importance of lipooligosaccharide structure in determining gonococcal resistance to hydrophobic antimicrobial agents resulting from the mtr efflux system. Mol Microbiol 1995; 16:1001-9. [PMID: 7476176 DOI: 10.1111/j.1365-2958.1995.tb02325.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Levels of gonococcal resistance to antimicrobial hydrophobic agents (HAs) are controlled by the mtr (multiple transferrable resistance) system, composed of the mtrRCDE genes. The mtrR gene encodes a transcriptional repressor that appears to regulate expression of the upstream and divergent mtrCDE operon. The mtrCDE genes encode membrane proteins analogous to the MexABOprK proteins of Pseudomonas aeruginosa that mediate export of structurally diverse antimicrobial agents. In this study we found that a single base pair deletion in a 13 bp inverted repeat sequence within the mtrR promoter resulted in increased resistance of gonococci to both crystal violet (CV) and erythromycin (ERY) as well as to the more lipophilic non-ionic detergent Triton X-100 (TX-100). However, this cross-resistance was contingent on the production of a full-length lipooligosaccharide (LOS) by the recipient strain used in transformation experiments. Introduction of this mutation (mtrR-171) into three chemically distinct deep-rough LOS mutants by transformation resulted in a fourfold increase in resistance to TX-100 compared with a 160-fold increase in an isogenic strain producing a full-length LOS. However, both wild-type and deep-rough LOS strains exhibited an eightfold increase in resistance to CV and ERY as a result of the mtrR-171 mutation. This suggests that gonococci have different LOS structural requirements for mtr-mediated resistance to HAs that differ in their lipophilic properties. Evidence is presented that gonococci exclude HAs by an energy-dependent efflux process mediated by the mtr system.
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Affiliation(s)
- C E Lucas
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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MacDonald MA, Southworth SH, Levin JC, Henins A, Deslattes RD, LeBrun T, Azuma Y, Cowan PL, Karlin BA. Evolution of x-ray resonance Raman scattering into x-ray fluorescence from the excitation of xenon near the L3 edge. Phys Rev A 1995; 51:3598-3603. [PMID: 9912026 DOI: 10.1103/physreva.51.3598] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Abstract
Wavelength dispersive crystal diffraction spectrometry has been applied to the measurement of the accelerating voltage on an x-ray source in a prototype experiment in the mammographic source. The results indicate that this noninvasive approach can yield determinations of such voltages within 0.1 kV, a level of imprecision that appears adequate for high-level standardization of such potentials.
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Affiliation(s)
- R D Deslattes
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899
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40
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Levin JC, Short RT, Biedermann C, Cederquist H, Elston SB, O C, Sellin IA. Determination of mean energies and impact parameters characteristic of charge-changing reactions. Phys Rev A 1994; 49:228-235. [PMID: 9910223 DOI: 10.1103/physreva.49.228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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41
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Levin JC, Sellin IA, Johnson BM, Lindle DW, Miller RD, Berrah N, Azuma Y, Berry HG, Lee D. High-energy behavior of the double photoionization of helium from 2 to 12 keV. Phys Rev A 1993; 47:R16-R19. [PMID: 9908985 DOI: 10.1103/physreva.47.r16] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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42
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Cederquist H, Andersson H, Beebe E, Biedermann C, Broström L, Gao H, Hutton R, Levin JC, Liljeby L, Pajek M, Quinteros T, Selberg N, Sigray P. Increase of true double-electron-capture cross sections in slow Xeq+-(Xe,He) collisions at very high q. Phys Rev A 1992; 46:2592-2595. [PMID: 9908417 DOI: 10.1103/physreva.46.2592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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43
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Kravis SD, Church DA, Johnson BM, Meron M, Jones KW, Levin JC, Sellin IA, Azuma Y, Berrah-Mansour N, Berry HG, Druetta M. Electron transfer from H2 and Ar to stored multiply charged argon ions produced by synchrotron radiation. Phys Rev A 1992; 45:6379-6387. [PMID: 9907758 DOI: 10.1103/physreva.45.6379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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44
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Andersson LR, Cederquist H, Bárány A, Liljeby L, Biedermann C, Levin JC, Keller N, Elston SB, Gibbons JP, Sellin IA. One- and two-step double-electron capture in slow Ar6+-He collisions. Phys Rev A 1992; 45:R4-R7. [PMID: 9906763 DOI: 10.1103/physreva.45.r4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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45
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Levin JC, Lindle DW, Keller N, Miller RD, Azuma Y, Mansour NB, Berry HG, Sellin IA. Measurement of the ratio of double-to-single photoionization of helium at 2.8 keV using synchrotron radiation. Phys Rev Lett 1991; 67:968-971. [PMID: 10045036 DOI: 10.1103/physrevlett.67.968] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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46
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Andersson LR, Cederquist H, Bárány A, Liljeby L, Biedermann C, Levin JC, Keller N, Elston SB, Gibbons JP, Kimura K, Sellin IA. Simultaneous single-electron capture and projectile-core excitation enhanced through configuration interaction in very slow Ar6+-He collisions. Phys Rev A 1991; 43:4075-4078. [PMID: 9905504 DOI: 10.1103/physreva.43.4075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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47
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Kimura K, Gibbons JP, Elston SB, Biedermann C, DeSerio R, Keller N, Levin JC, Breinig M, Burgdörfer J, Sellin IA. Convoy electrons emitted from resonant coherently excited ions. Phys Rev Lett 1991; 66:25-28. [PMID: 10043133 DOI: 10.1103/physrevlett.66.25] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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48
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Biedermann C, Levin JC, Short RT, Elston SB, Gibbons JP, Sellin IA, Cederquist H, Andersson LR, Andersson H, Liljeby L. Total-capture cross sections for very slow Ar4+-Ar and Ar6+-Ar collisions. Phys Rev A 1990; 42:6905-6908. [PMID: 9903994 DOI: 10.1103/physreva.42.6905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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49
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Levin JC, Biedermann C, Keller N, Liljeby L, O C, Short RT, Sellin IA, Lindle DW. Argon-photoion-Auger-electron coincidence measurements following K-shell excitation by synchrotron radiation. Phys Rev Lett 1990; 65:988-991. [PMID: 10043077 DOI: 10.1103/physrevlett.65.988] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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50
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Biedermann C, Cederquist H, Andersson LR, Levin JC, Short RT, Elston SB, Gibbons JP, Andersson H, Liljeby L, Sellin IA. Experimental and model angular distributions of one- and two-electron capture processes in 0.5-20 eV/u Ar4+-Ar collisions. Phys Rev A 1990; 41:5889-5908. [PMID: 9902989 DOI: 10.1103/physreva.41.5889] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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