Dissociation between the effects of oxygen and pressure on matrix metalloproteinase-2, -7, and -9 expression in human airway epithelial cells.

We tested the hypothesis that hyperoxia or pressure exposure differentially activates expression of cytokines and/or matrix modeling proteins in human airway epithelial cells. Calu-3 epithelial cell monolayers were cultured on transwell plates with the apical surface exposed to gas. Following establishment of baseline, plates were placed in a chamber and exposed to: control (21% O (2); atm), hyperoxia (60% O (2); atm), pressure (21% O (2); 40 cm H (2)O), and combination (60% O (2); 40 cm H (2)O).

Effects of oxygen concentration and exposure time on cultured human airway epithelial cells.

Objectives: To distinguish the direct effects of oxygen dose and exposure time on human airway epithelial cells. We hypothesized that progressive oxygen exposure would induce cell dysfunction and inflammation in a dose-dependent manner.

Design: Interventional laboratory study.

Growth and development in a heliox incubator environment: a long-term safety study.

Background: Neonates exposed to mechanical ventilation may develop bronchopulmonary dysplasia (BPD). BPD neonates exhibit a 25-30% increase in energy expenditure which may decrease the rate of growth and development. Heliox has been shown to improve pulmonary function and may decrease energy expenditure.

A prototype infant incubator for heliox therapy.

Heliox (Hx) gas has been shown to improve pulmonary function in infants, but methods for its delivery are invasive and problematic. To this end, we modified an Isolette (Hill-Rom Air-Shields) infant incubator (Hxl) to deliver Hx respiratory gas mixtures noninvasively while providing thermal stability for neonatal care in the Neonatal Intensive Care Unit (NICU). In vitro tests and in vivo animal studies were performed to compare the original design specifications and established baseline performance criteria for the Hxl design.

Physiologic implications of helium as a carrier gas for inhaled nitric oxide in a neonatal model of Bethanecol-induced bronchoconstriction.

Objective: To compare heliox to nitrogen-oxygen (nitrox) as a carrier gas for inducible nitric oxide (iNO) in the presence of pharmacologically inhaled bronchoconstriction. We hypothesized that respiratory resistance and gas exchange would improve when iNO is delivered with heliox.

Design: Interventional laboratory study.

Expression of matrix metalloproteinases 2, 7 and 9, and their tissue inhibitors 1 and 2, in developing rabbit tracheae.

Background: Structural changes in the developing conducting airway impact the rigidity of the airway, altering the airway's ability to sustain its shape during ventilation. The developmental changes in airway compliance oppose the changes in compliance of the developing lung; thus the expression profiles of matrix modeling proteins likely are also opposite in these developing organs.

Objectives: To determine the profiles of matrix metalloproteinases (MMPs) -2, -7, and -9 and tissue inhibitors (TIMPs) -1 and -2 in the developing trachea and test the hypothesis these profiles would contrast those previously reported for the lung.