Relationship between epa level of supervision with their associated subcompetency milestone levels in pediatric fellow assessment.

BACKGROUND: Entrustable Professional Activities (EPA) and competencies represent components of a competency-based education framework. EPAs are assessed based on the level of supervision (LOS) necessary to perform the activity safely and effectively. The broad competencies, broken down into narrower subcompetencies, are assessed using milestones, observable behaviors of one's abilities along a developmental spectrum. Integration of the two methods, accomplished by mapping the most relevant subcompetencies to each EPA, may provide a cross check between the two forms of assessment and uncover those subcompetencies that have the greatest influence on the EPA assessment. OBJECTIVES: We hypothesized that 1) there would be a strong correlation between EPA LOS ratings with the milestone levels for the subcompetencies mapped to the EPA; 2) some subcompetencies would be more critical in determining entrustment decisions than others, and 3) the correlation would be weaker if the analysis included only milestones reported to the Accreditation Council for Graduate Medical Education (ACGME). METHODS: In fall 2014 and spring 2015, the Subspecialty Pediatrics Investigator Network asked Clinical Competency Committees to assign milestone levels to each trainee enrolled in a pediatric fellowship for all subcompetencies mapped to 6 Common Pediatric Subspecialty EPAs as well as provide a rating for each EPA based upon a 5-point LOS scale. RESULTS: One-thousand forty fellows were assessed in fall and 1048 in spring, representing about 27% of all fellows. For each EPA and in both periods, the average milestone level was highly correlated with LOS (rho range 0.59-0.74; p < 0.001). Correlations were similar when using a weighted versus unweighted milestone score or using only the ACGME reported milestones (p > 0.05). CONCLUSIONS: We found a strong relationship between milestone level and EPA LOS rating but no difference if the subcompetencies were weighted, or if only milestones reported to the ACGME were used. Our results suggest that representative behaviors needed to effectively perform the EPA, such as key subcompetencies and milestones, allow for future language adaptations while still supporting the current model of assessment. In addition, these data provide additional validity evidence for using these complementary tools in building a program of assessment.

Comparison of knowledge acquisition and retention following traditional didactic vs. flipped classroom education utilizing a standardized national curriculum: a randomized controlled trial.

OBJECTIVE: Measure the effectiveness of and preference for a standardized, national curriculum utilizing flipped classrooms (FC) in neonatal-perinatal medicine (NPM) fellowships. STUDY DESIGN: Multicentered equivalence, cluster randomized controlled trial of NPM fellowship programs randomized to receive standardized physiology education as in-class lectures (traditional didactic, TD arm) or as pre-class online videos followed by in-class discussions (FC arm). Four multiple-choice question quizzes and three surveys were administered to measure knowledge acquisition, retention, and educational preferences. RESULTS: 530 fellows from 61 NPM fellowships participated. Quiz performance was comparable between groups at all time points (p = NS, TD vs FC at 4 time points). Post intervention, more fellows in both groups preferred group discussions (pre/post FC 42% vs. 58%, P = 0.002; pre/post TD 43% vs. 60%, P = < 0.001). FC fellows were more likely to rate classroom effectiveness positively (FC/TD, 70% vs. 36%, P < 0.001). CONCLUSIONS: FCs promote knowledge acquisition and retention equivalent to TD and FC modalities are preferred by fellows.

Hydrocortisone to Improve Survival without Bronchopulmonary Dysplasia.

BACKGROUND: Bronchopulmonary dysplasia is a prevalent complication after extremely preterm birth. Inflammation with mechanical ventilation may contribute to its development. Whether hydrocortisone treatment after the second postnatal week can improve survival without bronchopulmonary dysplasia and without adverse neurodevelopmental effects is unknown. METHODS: We conducted a trial involving infants who had a gestational age of less than 30 weeks and who had been intubated for at least 7 days at 14 to 28 days. Infants were randomly assigned to receive either hydrocortisone (4 mg per kilogram of body weight per day tapered over a period of 10 days) or placebo. Mandatory extubation thresholds were specified. The primary efficacy outcome was survival without moderate or severe bronchopulmonary dysplasia at 36 weeks of postmenstrual age, and the primary safety outcome was survival without moderate or severe neurodevelopmental impairment at 22 to 26 months of corrected age. RESULTS: We enrolled 800 infants (mean [±SD] birth weight, 715±167 g; mean gestational age, 24.9±1.5 weeks). Survival without moderate or severe bronchopulmonary dysplasia at 36 weeks occurred in 66 of 398 infants (16.6%) in the hydrocortisone group and in 53 of 402 (13.2%) in the placebo group (adjusted rate ratio, 1.27; 95% confidence interval [CI], 0.93 to 1.74). Two-year outcomes were known for 91.0% of the infants. Survival without moderate or severe neurodevelopmental impairment occurred in 132 of 358 infants (36.9%) in the hydrocortisone group and in 134 of 359 (37.3%) in the placebo group (adjusted rate ratio, 0.98; 95% CI, 0.81 to 1.18). Hypertension that was treated with medication occurred more frequently with hydrocortisone than with placebo (4.3% vs. 1.0%). Other adverse events were similar in the two groups. CONCLUSIONS: In this trial involving preterm infants, hydrocortisone treatment starting on postnatal day 14 to 28 did not result in substantially higher survival without moderate or severe bronchopulmonary dysplasia than placebo. Survival without moderate or severe neurodevelopmental impairment did not differ substantially between the two groups. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT01353313.).

Essentials of neonatal-perinatal medicine fellowship: scholarship perspective.

Neonatal-perinatal medicine fellows must achieve a meaningful accomplishment in scholarly activity as part of their training. Despite the requirement for scholarly training in fellowship, there is a vanishingly small number of MD-only physician-scientists pursuing a research-oriented career. Recent neonatal trainees have identified several factors that preclude their careers in research-focused academic neonatology, including lower pay in academic positions, inadequate training in research techniques, and the perception that individuals in research careers have a poor work-life balance. High competition for limited pediatric research funds also contributes to a diminishing pool of physician-scientists in neonatology. This small number of physician-scientists is threatened by a high rate of attrition among physicians who enter this career path. In order to prevent further declines in the number of neonatal physician-scientists, we need improvements in funding and strong intra- and cross-institutional mentorship to foster individuals interested in a career as a physician-scientist.

Fellow Entrustment for the Common Pediatric Subspecialty Entrustable Professional Activities Across Subspecialties.

OBJECTIVE: To determine the relationship between level of supervision (LOS) ratings for the Common Pediatric Subspecialty Entrustable Professional Activities (EPAs) with their associated subcompetency milestones across subspecialties and by fellowship training year. METHODS: Clinical Competency Committees (CCCs) in 14 pediatric subspecialties submitted LOS ratings for 6 Common Subspecialty EPAs and subcompetency milestone levels mapped to these EPAs. We examined associations between these subcompetency milestone levels and LOS ratings across subspecialty training year by fitting per-EPA linear mixed effects models, regressing LOS rating on milestone level and on training year. RESULTS: CCCs from 211 pediatric fellowship programs provided data for 369 first, 336 second, and 331 third year fellows. Mean subcompetency milestone levels increased similarly among subspecialties for most EPAs compared with the reference, Adolescent Medicine. Mean subcompetency milestones mapped to each EPA and mean EPA LOS ratings generally increased by training year across all subspecialties. CONCLUSIONS: Subcompetency milestones levels mapped to each Common Subspecialty EPA and the EPA LOS ratings increase similarly across subspecialties and by training year, providing validity evidence for using EPA LOS to assess pediatric subspecialty trainee performance. This study supports the development of tools to facilitated the CCC evaluation process across all pediatric subspecialties.

Achieving Entrustable Professional Activities During Fellowship.

BACKGROUND AND OBJECTIVES: Entrustable Professional Activities (EPAs) were developed to assess pediatric fellows. We previously showed that fellowship program directors (FPDs) may graduate fellows who still require supervision. How this compares with their expectations for entrustment of practicing subspecialists is unknown. METHODS: We surveyed US FPDs in 14 pediatric subspecialties through the Subspecialty Pediatrics Investigator Network between April and August 2017. For each of 7 common pediatric subspecialty EPAs, we compared the minimum level of supervision that FPDs required for graduation with the level they expected of subspecialists for safe and effective practice using the Friedman rank sum test and paired t test. We compared differences between subspecialties using linear regression. RESULTS: We collected data from 660 FPDs (response rate 82%). For all EPAs, FPDs did not require fellows to reach the level of entrustment for graduation that they expected of subspecialists to practice (P < .001). FPDs expected the least amount of supervision for the EPAs consultation and handovers. Mean differences between supervision levels for graduation and practice were smaller for clinical EPAs (consultation, handovers, lead a team) when compared with nonclinical EPAs (quality improvement, management, lead the profession and scholarship; P = .001) and were similar across nearly all subspecialties. CONCLUSIONS: Fellowship graduates may need continued development of clinical and nonclinical skills in their early practice period, underscoring a need for continued assessment and mentoring. Graduation readiness must be based on clear requirements, with alignment of FPD expectations and regulatory standards, to ensure quality care for patients.

Value, Strengths, and Challenges of e-Learning Modules Paired with the Flipped Classroom for Graduate Medical Education: A Survey from the National Neonatology Curriculum.

OBJECTIVE: This study aimed to determine the value, strengths, and challenges of implementing an e-learning based flipped classroom (FC) educational modality as part of the standardized physiology National Neonatology Curriculum (NNC), created for neonatal-perinatal medicine (NPM) fellow learners and faculty educators. STUDY DESIGN: This is a cross-sectional study of NPM fellows and faculty educators who utilized at least one of the e-learning based NNC FC respiratory physiology programs between May and September 2018. Participants were surveyed anonymously regarding their experiences participating in the NNC, including measures of preparation time. A combination of descriptive statistics and proportion comparisons were used for data analysis. RESULTS: Among 172 respondents, the majority of fellow and faculty respondents reported positive attitudes toward the educational content and case discussions, and the majority supported national standardization of NPM physiology education (92%). Fellows reported greater preclass preparation for their FC compared with previous didactic lectures (30-60 vs. 0-15 minutes, p < 0.01). Faculty facilitators reported less preparation time before facilitating a FC compared with the time required for creating a new didactic lecture (median: 60 vs. 240 minutes, p < 0.01). Both fellows and faculty respondents preferred the FC approach to traditional didactics, with fellows showing a greater degree of preference than faculty (68 vs. 52%, respectively, p = 0.04). CONCLUSION: Fellows and faculty educators supported the FC learning, reporting peer-to-peer learning, and the establishment of a learning community which promotes adult learning and critical thinking skills. A national physiology curriculum creates equitable and engaging educational experiences for all NPM fellows while reducing individual program burden of content creation. Our findings further supported the development of an NNC using a flipped classroom modality.

Agreement of Program Directors With Clinical Competency Committees for Fellow Entrustment.

OBJECTIVES: Fellowship program directors (FPD) and Clinical Competency Committees (CCCs) both assess fellow performance. We examined the association of entrustment levels determined by the FPD with those of the CCC for 6 common pediatric subspecialty entrustable professional activities (EPAs), hypothesizing there would be strong correlation and minimal bias between these raters. METHODS: The FPDs and CCCs separately assigned a level of supervision to each of their fellows for 6 common pediatric subspecialty EPAs. For each EPA, we determined the correlation between FPD and CCC assessments and calculated bias as CCC minus FPD values for when the FPD was or was not a member of the CCC. In addition, we examined the effect of program size, FPD understanding of EPAs, and subspecialty on the correlations. Data were obtained in fall 2014 and spring 2015. RESULTS: A total of 1040 fellows were assessed in the fall and 1048 in the spring. In both periods and for each EPA, there was a strong correlation between FPD and CCC supervision levels (P < .001). The correlation was somewhat lower when the FPD was not a CCC member (P < .001). Overall bias in both periods was small. CONCLUSIONS: The correlation between FPD and CCC assignment of EPA supervision levels is strong. Although slightly weaker when the FPD is not a CCC member, bias is small, so this is likely unimportant in determining fellow entrustment level. The similar performance ratings of FPDs and CCCs support the validity argument for EPAs as competency-based assessment tools.

Effects of Myo-inositol on Type 1 Retinopathy of Prematurity Among Preterm Infants <28 Weeks' Gestational Age: A Randomized Clinical Trial.

Importance: Previous studies of myo-inositol in preterm infants with respiratory distress found reduced severity of retinopathy of prematurity (ROP) and less frequent ROP, death, and intraventricular hemorrhage. However, no large trials have tested its efficacy or safety. Objective: To test the adverse events and efficacy of myo-inositol to reduce type 1 ROP among infants younger than 28 weeks' gestational age. Design, Setting, and Participants: Randomized clinical trial included 638 infants younger than 28 weeks' gestational age enrolled from 18 neonatal intensive care centers throughout the United States from April 17, 2014, to September 4, 2015; final date of follow-up was February 12, 2016. The planned enrollment of 1760 participants would permit detection of an absolute reduction in death or type 1 ROP of 7% with 90% power. The trial was terminated early due to a statistically significantly higher mortality rate in the myo-inositol group. Interventions: A 40-mg/kg dose of myo-inositol was given every 12 hours (initially intravenously, then enterally when feeding; n = 317) or placebo (n = 321) for up to 10 weeks. Main Outcomes and Measures: Type 1 ROP or death before determination of ROP outcome was designated as unfavorable. The designated favorable outcome was survival without type 1 ROP. Results: Among 638 infants (mean, 26 weeks' gestational age; 50% male), 632 (99%) received the trial drug or placebo and 589 (92%) had a study outcome. Death or type 1 ROP occurred more often in the myo-inositol group vs the placebo group (29% vs 21%, respectively; adjusted risk difference, 7% [95% CI, 0%-13%]; adjusted relative risk, 1.41 [95% CI, 1.08-1.83], P = .01). All-cause death before 55 weeks' postmenstrual age occurred in 18% of the myo-inositol group and in 11% of the placebo group (adjusted risk difference, 6% [95% CI, 0%-11%]; adjusted relative risk, 1.66 [95% CI, 1.14-2.43], P = .007). The most common serious adverse events up to 7 days of receiving the ending dose were necrotizing enterocolitis (6% for myo-inositol vs 4% for placebo), poor perfusion or hypotension (7% vs 4%, respectively), intraventricular hemorrhage (10% vs 9%), systemic infection (16% vs 11%), and respiratory distress (15% vs 13%). Conclusions and Relevance: Among premature infants younger than 28 weeks' gestational age, treatment with myo-inositol for up to 10 weeks did not reduce the risk of type 1 ROP or death vs placebo. These findings do not support the use of myo-inositol among premature infants; however, the early termination of the trial limits definitive conclusions.

Safety and pharmacokinetics of multiple dose myo-inositol in preterm infants.

BACKGROUND: Preterm infants with respiratory distress syndrome (RDS) given inositol had reduced bronchopulmonary dysplasia (BPD), death and severe retinopathy of prematurity (ROP). We assessed the safety and pharmacokinetics of daily inositol to select a dose providing serum levels previously associated with benefit, and to learn if accumulation occurred when administered throughout the normal period of retinal vascularization. METHODS: Infants ≤ 29 wk GA (n = 122, 14 centers) were randomized and treated with placebo or inositol at 10, 40, or 80 mg/kg/d. Intravenous administration converted to enteral when feedings were established, and continued to the first of 10 wk, 34 wk postmenstrual age (PMA) or discharge. Serum collection employed a sparse sampling population pharmacokinetics design. Inositol urine losses and feeding intakes were measured. Safety was prospectively monitored. RESULTS: At 80 mg/kg/d mean serum levels reached 140 mg/l, similar to Hallman's findings. Levels declined after 2 wk, converging in all groups by 6 wk. Analyses showed a mean volume of distribution 0.657 l/kg, clearance 0.058 l/kg/h, and half-life 7.90 h. Adverse events and comorbidities were fewer in the inositol groups, but not significantly so. CONCLUSION: Multiple dose inositol at 80 mg/kg/d was not associated with increased adverse events, achieves previously effective serum levels, and is appropriate for investigation in a phase III trial.

Elective delivery before 39 weeks: the risk of infant admission to the neonatal intensive care unit.

Despite American College of Obstetricians and Gynecologists guidelines suggesting that non-urgent planned deliveries be scheduled at/after 39 weeks; elective delivery before 39 weeks occurs often in the United States. The objective of this study is to estimate the elective delivery rate between 36(0/7) and 38(6/7) weeks gestation and compare NICU admission rates between elective and non-elective deliveries. We conducted a retrospective cohort (n = 1,577) study. Charts were reviewed for all singleton deliveries (2006-2007) between 36(0/7) and 38(6/7) weeks gestation taking place at one hospital in NYS to determine delivery status. We computed adjusted relative risks (RR) with 95% confidence intervals (CI) for elective delivery in relation to NICU admission using robust Poisson regression. 32.8% of all births were elective: 20.7% of vaginal and 55.7% of cesarean births. Elective delivery increased with increasing gestational age. After controlling for potential confounders, infants born via a vaginal elective delivery (RR = 1.40, CI: 1.00, 1.94), an elective cesarean (RR = 2.05, CI: 1.53, 2.76), or a non-elective cesarean (RR = 2.00, CI: 1.50, 2.66) are at significantly increased risk of NICU admission compared to infants born via a non-elective vaginal delivery. Elective delivery before 39 weeks is common and increases the risk of infant NICU admission.

Neonatal oxygen adversely affects lung function in adult mice without altering surfactant composition or activity.

Despite its potentially adverse effects on lung development and function, supplemental oxygen is often used to treat premature infants in respiratory distress. To understand how neonatal hyperoxia can permanently disrupt lung development, we previously reported increased lung compliance, greater alveolar simplification, and disrupted epithelial development in adult mice exposed to 100% inspired oxygen fraction between postnatal days 1 and 4. Here, we investigate whether oxygen-induced changes in lung function are attributable to defects in surfactant composition and activity, structural changes in alveolar development, or both. Newborn mice were exposed to room air or 40%, 60%, 80%, or 100% oxygen between postnatal days 1 and 4 and allowed to recover in room air until 8 wk of age. Lung compliance and alveolar size increased, and airway resistance, airway elastance, tissue elastance, and tissue damping decreased, in mice exposed to 60-80% oxygen; changes were even greater in mice exposed to 100% oxygen. These alterations in lung function were not associated with changes in total protein content or surfactant phospholipid composition in bronchoalveolar lavage. Moreover, surface activity and total and hydrophobic protein content were unchanged in large surfactant aggregates centrifuged from bronchoalveolar lavage compared with control. Instead, the number of type II cells progressively declined in 60-100% oxygen, whereas levels of T1alpha, a protein expressed by type I cells, were comparably increased in mice exposed to 40-100% oxygen. Thickened bundles of elastin fibers were also detected in alveolar walls of mice exposed to > or = 60% oxygen. These findings support the hypothesis that changes in lung development, rather than surfactant activity, are the primary causes of oxygen-altered lung function in children who were exposed to oxygen as neonates. Furthermore, the disruptive effects of oxygen on epithelial development and lung mechanics are not equivalently dose dependent.

Transcriptional responses of Mycobacterium tuberculosis to lung surfactant.

This study uses microarray analyses to examine gene expression profiles for Mycobacterium tuberculosis (Mtb) induced by exposure in vitro to bovine lung surfactant preparations that vary in apoprotein content: (i) whole lung surfactant (WLS) containing the complete mixture of endogenous lipids and surfactant proteins (SP)-A, -B, -C, and -D; (ii) extracted lung surfactant (CLSE) containing lipids plus SP-B and -C; (iii) column-purified surfactant lipids (PPL) containing no apoproteins, and (iv) purified human SP-A. Exposure to WLS evoked a multitude of transcriptional responses in Mtb, with 52 genes up-regulated and 23 genes down-regulated at 30min exposure, plus 146 genes up-regulated and 27 genes down-regulated at 2h. Notably, WLS rapidly induced several membrane-associated lipases that presumptively act on surfactant lipids as substrates, and a large number of genes involved in the synthesis of phthiocerol dimycocerosate (PDIM), a cell wall component known to be important in macrophage interactions and Mtb virulence. Exposure of Mtb to CLSE, PPL, or purified SP-A caused a substantially weaker transcriptional response (

Pharmacotherapy of acute lung injury and acute respiratory distress syndrome.

Acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) are characterized by rapid-onset respiratory failure following a variety of direct and indirect insults to the parenchyma or vasculature of the lungs. Mortality from ALI/ARDS is substantial, and current therapy primarily emphasizes mechanical ventilation and judicial fluid management plus standard treatment of the initiating insult and any known underlying disease. Current pharmacotherapy for ALI/ARDS is not optimal, and there is a significant need for more effective medicinal chemical agents for use in these severe and lethal lung injury syndromes. To facilitate future chemical-based drug discovery research on new agent development, this paper reviews present pharmacotherapy for ALI/ARDS in the context of biological and biochemical drug activities. The complex lung injury pathophysiology of ALI/ARDS offers an array of possible targets for drug therapy, including inflammation, cell and tissue injury, vascular dysfunction, surfactant dysfunction, and oxidant injury. Added targets for pharmacotherapy outside the lungs may also be present, since multiorgan or systemic pathology is common in ALI/ARDS. The biological and physiological complexity of ALI/ARDS requires the consideration of combined-agent treatments in addition to single-agent therapies. A number of pharmacologic agents have been studied individually in ALI/ARDS, with limited or minimal success in improving survival. However, many of these agents have complementary biological/biochemical activities with the potential for synergy or additivity in combination therapy as discussed in this article.

Surfactant for pediatric acute lung injury.

This article reviews exogenous surfactant therapy and its use in mitigating acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) in infants, children, and adults. Biophysical and animal research documenting surfactant dysfunction in ALI/ARDS is described, and the scientific rationale for treatment with exogenous surfactant is discussed. Major emphasis is placed on reviewing clinical studies of surfactant therapy in pediatric and adult patients who have ALI/ARDS. Particular advantages from surfactant therapy in direct pulmonary forms of these syndromes are described. Also discussed are additional factors affecting the efficacy of exogenous surfactants in ALI/ARDS.

Surfactant dysfunction in lung contusion with and without superimposed gastric aspiration in a rat model.

This study investigates surfactant dysfunction in rats with lung contusion (LC) induced by blunt chest trauma. Rats at 24 h postcontusion had a decreased percent content of large surfactant aggregates in cell-free bronchoalveolar lavage (BAL) and altered large-aggregate composition with decreased phosphatidylcholine (PC), increased lyso-PC, and increased protein compared with uninjured controls. The surface activity of large aggregates on a pulsating bubble surfactometer was also severely impaired at 24 h postcontusion. Decreases in large surfactant aggregate content and surface activity were improved, but still apparent, at 48 and 72 h postcontusion compared with uninjured control rats and returned to normal by 96 h postcontusion. The functional importance of surfactant abnormalities in LC injury was documented in pilot studies showing that exogenous surfactant replacement at 24 h postcontusion improved inflation/deflation lung volumes. Additional experiments investigated a clinically relevant combination of LC plus gastric aspiration (combined acid and small gastric food particles) and found reductions in large surfactant aggregates in BAL similar to those for LC. However, rats given LC + combined acid and small gastric food particles versus LC had more severe surfactant dysfunction based on decreases in surface activity and alterations in large aggregate composition. Combined data for all animal groups had strong statistical correlations between surfactant dysfunction (increased minimum surface tension, decreased large aggregates in BAL, decreased aggregate PC, and increased aggregate lyso-PC) and the severity of inflammatory lung injury (increased total protein, albumin, protein/phospholipid ratio, neutrophils, and erythrocytes in BAL plus increased whole lung myeloperoxidase activity). These results show that surfactant dysfunction is important in the pathophysiology of LC with or without concurrent gastric aspiration and provides a rationale for surfactant replacement therapy in these prevalent clinical conditions.

Peripheral cell wall lipids of Mycobacterium tuberculosis are inhibitory to surfactant function.

The transmission of Mycobacterium tuberculosis (TB) requires extensive damage to the lungs to facilitate bacterial release into the airways, and it is therefore likely that the microorganism has evolved mechanisms to exacerbate its local pathology. This study examines the inhibitory effects of lipids extracted and purified chromatographically from TB on the surface-active function of lavaged bovine lung surfactant (LS) and a clinically relevant calf lung surfactant extract (CLSE). Total lipids from TB greatly inhibited the surface activity of LS and CLSE on the pulsating bubble surfactometer at physical conditions applicable for respiration in vivo (37 degrees C, 20 cycles/min, 50% area compression). Minimum surface tensions for LS (0.5 mg/ml) and CLSE (1 mg/ml) were raised from <1 mN/m to 15.7+/-1.2 and 18.7+/-1.3 mN/m after 5 min of bubble pulsation in the presence of total TB lipids (0.15 mg/ml). TB mixed waxes (0.15 mg/ml) and TB trehalose monomycolates (TMMs, 0.15 mg/ml) also significantly inhibited the surface activity of LS and CLSE (minimum surface tensions of 10-16 mN/m after 5 min of bubble pulsation), as did purified trehalose 6,6'-dimycolate (TDM, cord factor). Phosphatidylinositol mannosides (PIMs, 0.15 mg/ml) from TB had no inhibitory effect on the surface activity of LS or CLSE. Concentration dependence studies showed that LS was also inhibited significantly by total TB lipids at 0.075 mg/ml, with a smaller activity decrease apparent even at 0.00375 mg/ml. These findings document that TB contains multiple lipids that can directly impair the biophysical function of endogenous and exogenous lung surfactants. Direct inhibition by TB lipids could worsen surfactant dysfunction caused by plasma proteins or other endogenous substances induced by inflammatory injury in the infected lungs. TB lipids could also inhibit the effectiveness of exogenous surfactants used to treat severe acute respiratory failure in TB patients meeting criteria for clinical acute lung injury (ALI) or the acute respiratory distress syndrome (ARDS).

Surfactant dysfunction and lung injury due to the E. coli virulence factor hemolysin in a rat pneumonia model.

This study tests the hypothesis that the virulence factor hemolysin (Hly) expressed by extraintestinal pathogenic Escherichia coli contributes to surfactant dysfunction and lung injury in a rat model of gram-negative pneumonia. Rats were instilled intratracheally with CP9 (wild type, Hly-positive), CP9hlyA (Hly-minus), CP9/pEK50 (supraphysiological Hly), or purified LPS. At 6 h postinfection, rats given CP9 had a decreased percentage content of large surfactant aggregates in cell-free bronchoalveolar lavage (BAL), decreased large aggregate surface activity, decreased Pa(O2)/FiO2) ratio, increased BAL albumin/protein levels, and increased histological evidence of lung injury compared with rats given CP9hlyA or LPS. In addition, rats given CP9/pEK50 or CP9 had decreased large aggregate surface activity, decreased Pa(O2)/FiO2) ratios, and increased BAL albumin/protein levels at 2 h postinfection compared with rats given CP9hlyA. The severity of permeability lung injury based on albumin/protein levels in BAL at 2 h was ordered as CP9/pEK50 > CP9 > CP9hlyA > normal saline controls. Total lung titers of bacteria were increased at 6 h in rats given CP9 vs. CP9hlyA, but bacterial titers were not significantly different at 2 h, indicating that increased surfactant dysfunction and lung injury were associated with Hly as opposed to bacterial numbers per se. Further studies in vitro showed that CP9 could directly lyse transformed pulmonary epithelial cells (H441 cells) but that indirect lysis of H441 cells secondary to Hly-induced neutrophil lysis did not occur. Together, these data demonstrate that Hly is an important direct mediator of surfactant dysfunction and lung injury in gram-negative pneumonia.