Pulmonary artery smooth muscle cell HIF-1α regulates endothelin expression via microRNA-543.

Pulmonary artery smooth muscle cells (PASMCs) express endothelin (ET-1), which modulates the pulmonary vascular response to hypoxia. Although cross-talk between hypoxia-inducible factor-1α (HIF-1α), an O2-sensitive transcription factor, and ET-1 is established, the cell-specific relationship between HIF-1α and ET-1 expression remains incompletely understood. We tested the hypotheses that in PASMCs 1) HIF-1α expression constrains ET-1 expression, and 2) a specific microRNA (miRNA) links HIF-1α and ET-1 expression. In human (h)PASMCs, depletion of HIF-1α with siRNA increased ET-1 expression at both the mRNA and protein levels ( P < 0.01). In HIF-1α-/- murine PASMCs, ET-1 gene and protein expression was increased ( P < 0.0001) compared with HIF-1α+/+ cells. miRNA profiles were screened in hPASMCs transfected with siRNA-HIF-1α, and RNA hybridization was performed on the Agilent (Santa Clara, CA) human miRNA microarray. With HIF-1α depletion, miRNA-543 increased 2.4-fold ( P < 0.01). In hPASMCs, miRNA-543 overexpression increased ET-1 gene ( P < 0.01) and protein ( P < 0.01) expression, decreased TWIST gene expression ( P < 0.05), and increased ET-1 gene and protein expression, compared with nontargeting controls ( P < 0.01). Moreover, we evaluated low passage hPASMCs from control and patients with idiopathic pulmonary arterial hypertension (IPAH). Compared with controls, protein expression of HIF-1α and Twist-related protein-1 (TWIST1) was decreased ( P < 0.05), and miRNA-543 and ET-1 expression increased ( P < 0.001) in hPASMCs from patients with IPAH. Thus, in PASMCs, loss of HIF-1α increases miRNA-543, which decreases Twist expression, leading to an increase in PASMC ET-1 expression. This previously undescribed link between HIF-1α and ET-1 via miRNA-543 mediated Twist suppression represents another layer of molecular regulation that might determine pulmonary vascular tone.

Embedding time-limited laboratory orders within computerized provider order entry reduces laboratory utilization.

OBJECTIVES: To test the hypothesis that limits on repeating laboratory studies within computerized provider order entry decrease laboratory utilization. DESIGN: Cohort study with historical controls. SETTING: A 20-bed PICU in a freestanding, quaternary care, academic children's hospital. PATIENTS: This study included all patients admitted to the pediatric ICU between January 1, 2008, and December 31, 2009. A total of 818 discharges were evaluated prior to the intervention (January 1, 2008, through December 31, 2008) and 1,021 patient discharges were evaluated postintervention (January 1, 2009, through December 31, 2009). INTERVENTION: A computerized provider order entry rule limited the ability to schedule repeating complete blood cell counts, chemistry, and coagulation studies to a 24-hour interval in the future. The time limit was designed to ensure daily evaluation of the utility of each test. MEASUREMENTS AND MAIN RESULTS: Initial analysis with t tests showed significant decreases in tests per patient day in the postintervention period (complete blood cell counts: 1.5 ± 0.1 to 1.0 ± 0.1; chemistry: 10.6 ± 0.9 to 6.9 ± 0.6; coagulation: 3.3 ± 0.4 to 1.7 ± 0.2; p < 0.01, all variables vs. preintervention period). Even after incorporating a trend toward decreasing laboratory utilization in the preintervention period into our regression analysis, the intervention decreased complete blood cell counts (p = 0.007), chemistry (p = 0.049), and coagulation (p = 0.001) tests per patient day. CONCLUSIONS: Limits on laboratory orders within the context of computerized provider order entry decreased laboratory utilization without adverse affects on mortality or length of stay. Broader application of this strategy might decrease costs, the incidence of iatrogenic anemia, and catheter-associated bloodstream infections.

Inhibiting NF-κB in the developing lung disrupts angiogenesis and alveolarization.

Bronchopulmonary dysplasia (BPD), a chronic lung disease of infancy, is characterized by arrested alveolar development. Pulmonary angiogenesis, mediated by the vascular endothelial growth factor (VEGF) pathway, is essential for alveolarization. However, the transcriptional regulators mediating pulmonary angiogenesis remain unknown. We previously demonstrated that NF-κB, a transcription factor traditionally associated with inflammation, plays a unique protective role in the neonatal lung. Therefore, we hypothesized that constitutive NF-κB activity is essential for postnatal lung development. Blocking NF-κB activity in 6-day-old neonatal mice induced the alveolar simplification similar to that observed in BPD and significantly reduced pulmonary capillary density. Studies to determine the mechanism responsible for this effect identified greater constitutive NF-κB in neonatal lung and in primary pulmonary endothelial cells (PEC) compared with adult. Moreover, inhibiting constitutive NF-κB activity in the neonatal PEC with either pharmacological inhibitors or RNA interference blocked PEC survival, decreased proliferation, and impaired in vitro angiogenesis. Finally, by chromatin immunoprecipitation, NF-κB was found to be a direct regulator of the angiogenic mediator, VEGF-receptor-2, in the neonatal pulmonary vasculature. Taken together, our data identify an entirely novel role for NF-κB in promoting physiological angiogenesis and alveolarization in the developing lung. Our data suggest that disruption of NF-κB signaling may contribute to the pathogenesis of BPD and that enhancement of NF-κB may represent a viable therapeutic strategy to promote lung growth and regeneration in pulmonary diseases marked by impaired angiogenesis.

A critical appraisal of "transfusion strategies for patients in pediatric intensive care units" by Lacroix J, Hebert PC, Hutchison, et al (N Engl J Med 2007; 356:1609-1619).

OBJECTIVE: To review the findings and discuss the implications of transfusion strategies in stable critically ill children. DESIGN: A critical appraisal of the article "Transfusion strategies for patients in pediatric intensive care units" by Lacroix J, Hebert PC, Hutchison, et al, published in the N Engl J Med in 2007 with literature review. FINDINGS: In this prospective, randomized, controlled, noninferiority trial the authors compared a liberal transfusion strategy, using a transfusion threshold of 9 g/dL, to a conservative transfusion strategy, using a transfusion threshold of 7 g/dL. The primary end point was multiple organ dysfunction syndrome (MODS) or progression of MODS. The authors found that when comparing the restrictive transfusion strategy to the liberal strategy, the absolute risk reduction for developing new or progressive MODS was only 0.4% (95% confidence interval, -4.6 -5.5). Using the restrictive protocol, the number needed to treat to prevent one red blood cell (RBC) transfusion was only two. The number of RBC units per patient in the restrictive group was 0.9, and in the liberal group was 1.7 (p < 0.001). When comparing the two strategies there was a relative reduction of 96% in the number of patients who had any transfusion exposure and a relative decrease of 44% in the number of transfusions administered in the restrictive strategy. CONCLUSIONS: Using a restrictive transfusion protocol with a transfusion threshold of 7 g/dL in stable critically ill children is as safe as using a liberal protocol and can decrease the number of patients exposed to RBC transfusions.

Clinical Decision Support for Pediatric Blood Product Prescriptions.

Since the beginning of the 20th century, blood products have been used to effectively treat life-threatening conditions. Over time, we have come to appreciate the many benefits along with significant risks inherent to blood product transfusions. As such, recommendations for the safe and effective use of blood products have evolved over time. Current evidence supports the use of restrictive transfusion strategies that can avoid the risks of unnecessary transfusions. In spite of good evidence, there is a considerable amount of variability in transfusion practices across providers. Clinical decision support (CDS) is an effective tool capable of increasing adherence to evidence-based practices. CDS has been used successfully to improve adherence to transfusion guidelines. Pediatric literature demonstrates strong evidence for the use of CDS to improve appropriateness of red blood cell and plasma transfusion utilization. Further studies in more diverse settings with more standardized reporting are needed to provide more clarity around the effectiveness of CDS in blood product prescriptions.

Computerized physician order entry with decision support decreases blood transfusions in children.

OBJECTIVE: Timely provision of evidence-based recommendations through computerized physician order entry with clinical decision support may improve use of red blood cell transfusions (RBCTs). METHODS: We performed a cohort study with historical controls including inpatients admitted between February 1, 2008, and January 31, 2010. A clinical decision-support alert for RBCTs was constructed by using current evidence. RBCT orders resulted in assessment of the patient's medical record with prescriber notification if parameters were not within recommended ranges. Primary end points included the average pretransfusion hemoglobin level and the rate of RBCTs per patient-day. RESULTS: In total, 3293 control discharges and 3492 study discharges were evaluated. The mean (SD) control pretransfusion hemoglobin level in the PICU was 9.83 (2.63) g/dL (95% confidence interval [CI]: 9.65-10.01) compared with the study value of 8.75 (2.05) g/dL (95% CI: 8.59-8.90) (P < .0001). The wards' control value was 7.56 (0.93) g/dL (95% CI: 7.47-7.65), the study value was 7.14 (1.01) g/dL (95% CI: 6.99-7.28) (P < .0001). The control PICU rate of RBCTs per patient-day was 0.20 (0.11) (95% CI: 0.13-0.27), the study rate was 0.14 (0.04) (95% CI: 0.11-0.17) (P = .12). The PICU's control rate was 0.033 (0.01) (95% CI: 0.02-0.04), and the study rate was 0.017 (0.007) (95% CI: 0.01-0.02) (P < .0001). There was no difference in mortality rates across all cohorts. CONCLUSIONS: Implementation of clinical decision-support alerts was associated with a decrease in RBCTs, which suggests improved adoption of evidence-based recommendations. This strategy might be widely applied to promote timely adoption of scientific evidence.