Hyperoxia causes increased albumin permeability of cultured endothelial monolayers

The effect of phasic eye movement activity on ventilation during rapid-eye-movement (REM) sleep was studied in seven healthy young adults by use of the respiratory inductive plethysmograph. Mean ventilation (VE) and ventilatory components during REM sleep were not significantly different from that seen in either stages 1-2 or 3-4 sleep. The percent of rib cage contribution to ventilation in REM sleep, 29.3 +/- 5.1%, was reduced compared with 54.4 +/- 5.8% in stage 1-2 and 52.2 +/- 4.3% in stage 3-4 sleep (P less than 0.005). When one separated breaths by the degree of associated phasic eye movement activity, it became apparent that breathing during REM sleep is very heterogeneous. Increasing eye movement activity was associated with inhibition of ventilation with a reduction in VE from 5.1 +/- 0.3 to 3.8 +/- 0.3 l/min. Tidal volume and frequency both fell, whereas inspiratory duration was unchanged. Compartmental ventilation was also affected, with the fall in the rib cage contribution from 37.8 +/- 6.4 to 15.3 +/- 5.6%. Chest wall and abdominal movement became more asynchronous as phasic-eye-movement activity increased and frank paradoxical breathing was seen.     

Directional fixation of mutations in vertebrate evolution

Summary We have made pairwise comparisons between the coding sequences of 21 genes from coldblooded vertebrates and 41 homologous sequences from warm-blooded vertebrates. In the case of 12 genes, GC levels were higher, especially in third codon positions, in warm-blooded vertebrates compared to cold-blooded vertebrates. Six genes showed no remarkable difference in GC level and three showed a lower level. In the first case, higher GC levels appear to be due to a directional fixation of mutations, presumably under the influence of body temperature (see Bernardi and Bernardi 1986b). These GC-richer genes of warm-blooded vertebrates were located, in all cases studied, in isochores higher in GC than those comprising the homologous genes of cold-blooded vertebrates. In the third case, increases appear to be due to a limited formation of GC-rich isochores which took place in some cold-blooded vertebrates after the divergence of warm-blooded vertebrates. The directional changes in the GC content of coding sequences and the evolutionary conservation of both increased and unchanged GC levels are in keeping with the existence of compositional constraints on the genome.     

Direct staining and visualization of endothelial monolayers cultured on synthetic polycarbonate filters

Endothelial and epithelial cells cultured on synthetic filter supports have been used to study permeability and transport under various experimental conditions. However, because of the non-transparent nature of these filters, morphological studies using light microscopy are not possible. Presently, investigators circumvent this problem by using cells cultured on glass coverslips, extrapolating morphological data from a system clearly different from that used for functional studies. We describe here a useful technique for direct staining and visualization of cells grown on polycarbonate filter supports, using fluorochrome probes and fluorescence microscopy. We have utilized acridine orange, rhodamine phalloidin, and an anti-vimentin monoclonal antibody to provide information about cell shape, monolayer configuration, and cytoskeletal protein distribution in cultured calf pulmonary artery endothelial cell monolayers. Comparison staining of coverslip and filter preparations revealed a number of clear differences in these parameters. This technique should enable investigators to perform the necessary studies to obtain direct correlations between functional and morphological data.     

Red blood cells protect endothelial cells against H2O2-mediated but not hyperoxia-induced damage

We studied the effect of intact red blood cells on the exogenous H2O2-mediated damage as well as on the hyperoxia-induced injury of cultured endothelial cells. Red blood cells protected endothelial cells against H2O2-mediated injury efficiently, but had no effect on the hyperoxia-induced damage. Failure of red blood cells to protect endothelial cells against hyperoxia-induced injury was not due to hemolysis. Furthermore, hyperoxia-exposed red blood cells were still capable of protecting endothelial cells against H2O2-mediated damage.     

Erythrocyte insufflation-induced protection against oxygen toxicity: role of cytokines.

We studied the pulmonary response of adult rats to erythrocyte (RBC) and RBC lysate insufflation to define the mechanism of RBC insufflation-induced protection against oxygen toxicity. Tracheal insufflation of 1 ml RBC (75%) or RBC lysate induced an intense pulmonary inflammatory response. Within 24 h of oxygen exposure, greater than 95% of insufflated RBCs was hemolyzed. The cell-free fraction of alveolar lavage fluids from RBC- or RBC lysate-insufflated rats had similar capacity in protecting endothelial cells against H2O2 cytotoxicity. However, RBC insufflation but not RBC lysate insufflation, protected rats against oxygen toxicity. There was marked erythrophagocytosis by alveolar macrophages of RBC-insufflated rats. Insufflation of RBCs, but not RBC lysate, resulted in production of tumor necrosis factor and interleukin 1, which could be recovered by bronchoalveolar lavages. When rats were insufflated with a combination of RBC lysate and cytokines at dosages within the range of cytokine levels achievable in alveolar lavage fluids by RBC insufflation, they became tolerant to oxygen. These results suggest that endogenously produced tumor necrosis factor and interleukin-1 as a result of RBC insufflation may play an important role in RBC insufflation-induced oxygen tolerance.     

Anchorage-dependent surface distribution and partition during freeze-fracture of viral transmembrane glycoproteins

We have compared in the same cell type the surface distribution and partition in freeze-fractured plasma membranes of Sindbis virus glycoproteins in three different situations: (i) in permanently transformed cells that express the glycoproteins as the only viral product; (ii) in cells in which prebound viruses were forced to fuse with the plasma membrane by low pH treatment; (iii) in virus-infected cells. We report here that the viral proteins expressed on the surface of transfected cells show a uniform and unclustered distribution; conversely, in Sindbis virus-infected cells they appear clustered, regionally distributed, and always associated with budding viruses (i.e., interacting with the nucleocapsid on the cytosolic side of the membrane). Furthermore, the viral proteins expressed on transfected cells or implanted by low pH-mediated fusion partition during freeze-fracture with the exoplasmic faces of the cell plasma membranes, whereas an opposite partition is observed in infected cells. These results strongly suggest that in infected cells the clustering and the partition with the protoplasmic faces of the plasma membrane depend only on the strong "anchorage" of the glycoproteins to the nucleocapsid.