Effect of a sustained inflation on regional distribution of gas and perfluorocarbon during partial liquid ventilation

The effect of perfluorocarbon-based artificial oxygen carriers on tissue-engineered trachea

The biological effect of the perfluorocarbon-based artificial oxygen carrier (Oxygent) was investigated in tissue-engineered trachea (TET) construction. Media supplemented with and without 10% Oxygent were compared in all assessments. Partial tissue oxygen tension (PtO(2)) was measured with polarographic microprobes; epithelial metabolism was monitored by microdialysis inside the TET epithelium perfused with the medium underneath. Chondrocyte-DegraPol constructs were cultured for 1 month with the medium before glycosaminoglycan assessment and histology. Tissue reaction of TET epithelial scaffolds immersed with the medium was evaluated on the chick embryo chorioallantoic membrane. Oxygent perfusion medium increased the TET epithelial PtO(2) (51.2 +/- 0.3 mm Hg vs. 33.4 +/- 0.3 mm Hg at 200 microm thickness; 12.5 +/- 0.1 mm Hg vs. 3.1 +/- 0.1 mm Hg at 400 microm thickness, p < 0.01) and decreased the lactate concentration (0.63 +/- 0.08 vs. 0.80 +/- 0.06 mmol/L, p < 0.05), lactate/pyruvate (1.87 +/- 0.26 vs. 3.36 +/- 10.13, p < 0.05), and lactate/glucose ratios (0.10 +/- 0.00 vs. 0.29 +/- 0.14, p < 0.05). Chondrocyte-DegraPol in Oxygent group presented lower glycosaminoglycan value (0.03 +/- 0.00 vs. 0.13 +/- 0.00, p < 0.05); histology slides showed poor acid mucopolysaccharides formation. Orthogonal polarization spectral imaging showed no difference in functional capillary density between the scaffolds cultured on chorioallantoic membranes. The foreign body reaction was similar in both groups. We conclude that Oxygent increases TET epithelial PtO(2), improves epithelial metabolism, does not impair angiogenesis, and tends to slow cartilage tissue formation.

Cooperative assembly and misfolding of CFTR domains in vivo

The cystic fibrosis transmembrane conductance regulator (CFTR) architecture consists of two membrane spanning domains (MSD1 and -2), two nucleotide binding domains (NBD1 and -2), and a regulatory (R) domain. Several point mutations lead to the channel misprocessing, with limited structural perturbation of the mutant domain. To gain more insight into the basis of CFTR folding defect, the contribution of domain-wise and cooperative domain folding was assessed by determining 1) the minimal domain combination that is recognized as native and can efficiently escape the endoplasmic reticulum (ER) retention and 2) the impact of mutation on the conformational coupling among domains. One-, two-, three-, and most of the four-domain assemblies were retained at the ER. Solubilization mutations, however, rescued the NBD1 processing defect conceivably by thermodynamic stabilization. The smallest folding unit that traversed the secretory pathway was composed of MSD1-NBD1-R-MSD2 as a linear or split polypeptide. Cystic fibrosis-causing missense mutations in the MSD1, NBD1, MSD2, and NBD2 caused conformational defect in multiple domains. We propose that cooperative posttranslational folding is required for domain stabilization and provides a plausible explanation for the global misfolding caused by point mutations dispersed along the full-length CFTR.