Browsing by Subject "Bronchopulmonary dysplasia"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Bronchopulmonary Dysplasia Impairs L-type Amino Acid Transporter-1 Expression in Human & Baboon Lung
    (2016-05) Bao, Erik
    Bronchopulmonary dysplasia (BPD) is an inflammatory lung disorder common in premature infants who undergo mechanical ventilation with supplemental oxygen. Inhaled nitric oxide (iNO) has been used to treat BPD, but clinical outcomes in preterm newborns have been equivocal. Previous studies showed that iNO’s effects in alveolar epithelial cells (AEC) are mediated by S-nitrosothiol uptake via L-type amino acid transporter-1 (LAT1). Because LAT1 expression could influence the efficacy of iNO therapy, I sought to determine whether pulmonary LAT1 expression is altered in preterm baboons with experimental BPD and human newborns susceptible to developing BPD. Using fixed lung obtained from 125d and 140d gestation baboons, LAT1 immunostaining was measured in control vs. BPD animals. In adult and gestational controls, LAT1 was strongly expressed in AECs. In 140d BPD lungs, however, LAT1 expression density in alveolar epithelial tissue was significantly decreased. In 125d BPD lungs, LAT1 expression was also significantly diminished in AECs and was instead ectopically localized to interstitial lung regions. The pattern of LAT1 expression in adult human lung was comparable to that observed in adult baboons. LAT1 expression was comparatively diminished in the lungs of premature newborns at autopsy. In human and baboon lung, pulmonary vascular cells expressed LAT1. In summary, LAT1 is expressed in AECs and pulmonary vascular cells in baboons and humans, and BPD pathophysiology decreases pulmonary LAT1 expression and alters its spatial localization. These results could explain the current ineffectiveness of iNO therapy in premature newborns with BPD, as well as guide future work on optimizing NO-based therapies.
  • Thumbnail Image
    ItemOpen Access
    Temperature Instability Over Time and Respiratory Morbidity in the Very Premature Infant
    (2020) Ralphe, Jane

    Very premature infants are at risk for thermal instability due to thermoregulatory immaturity. Thermal instability upon neonatal intensive care unit admission has been associated with mortality and morbidity in these infants. Bronchopulmonary dysplasia (BPD), a developmental respiratory morbidity, is the most common complication of very premature birth. BPD is associated with admission temperature instability; however, its relationship with longitudinal temperature instability is poorly understood. An exploratory mixed-methods approach was used to examine the association between very premature infant temperatures over time and acute and chronic respiratory morbidities. The impact of daily care and respiratory care on infant body temperatures over time was also examined.

    Research in the systematic literature review (Chapter 2) found that lower incubator temperatures can result in cold and dehumidified inspired air, and cold and dry inspired air can alter infant thermal stability. The studies in Chapter 3 and 4 found that infant temperatures (i.e., body, foot, abdominal-foot (temperature differential)) did not change significantly across the first five and 14 days of life, respectively. Daily care, respiratory care, and artificial respiratory support (i.e., MV, CPAP, RA) were associated with hypothermia. In addition, infants without chronic lung disease (CLD) had lower body temperatures and longer episodes of hypothermia compared to infants with CLD. Also, acute respiratory morbidities (i.e., bradycardia with desaturations and increases in supplemental oxygen and increased respiratory support) were associated with higher odds of hypothermia.

    The relationships between hypothermia and both daily care and respiratory care support the need for bundling infant care, and potentially limiting care duration. The associations between hypothermia and respiratory support and acute and chronic respiratory morbidities should be explored further using advanced longitudinal methodologies. Ecological momentary assessment (EMA) can help delineate antecedent-consequence relationships to guide future intervention studies that are designed to reduce infant thermal instability over time and its associated morbidities.