The effect of positive expiratory pressure breathing, alone and in combination with coughing, was investigated in eight patients with cystic fibrosis. Functional residual capacity and total lung capacity was measured with a body plethysmograph before, during, and immediately after breathing with expiratory pressure of 5 and 15 cm H20, and after a coughing period. The positive expiratory pressure breathing was carried out five times for two minutes with a two minute interval between each period. Mucus transport was measured in a peripheral lung region and over the whole lung by a radioactive aerosol tracer technique. Clearance measurements were carried out continuously during positive expiratory pressure breathing and during a control period. Two minutes' breathing with an expiratory pressure of 5 and 15 cm H2O caused an increase in mean (SEM) functional residual capacity from 2-6 (0-1) to 3-6 (0-3) and 4-4 (0-5) 1 and an increase in total lung capacity from 5-1 (0-2) to 5-9 (0-3) and 6-9 (0-4) 1. Lung volumes were higher during breathing with an expiratory pressure of 15 cm H20 than with 5 cm H20; both returned to baseline values immediately after positive expiratory pressure breathing.
In vivo selections are powerful tools for the directed evolution of enzymes. However, the need to link enzymatic activity to cellular survival makes selections for enzymes that do not fulfill a metabolic function challenging. Here, we present an in vivo selection strategy that leverages recoded organisms addicted to non‐canonical amino acids (ncAAs) to evolve biocatalysts that can provide these building blocks from synthetic precursors. We exemplify our platform by engineering carbamoylases that display catalytic efficiencies more than five orders of magnitude higher than those observed for the wild‐type enzyme for ncAA‐precursors. As growth rates of bacteria under selective conditions correlate with enzymatic activities, we were able to elicit improved variants from populations by performing serial passaging. By requiring minimal human intervention and no specialized equipment, we surmise that our strategy will become a versatile tool for the in vivo directed evolution of diverse biocatalysts.
57-Co-bleomycin is useful in the detection and staging of lung cancer, but the long half-life of 57Co (270 days) has discouraged its widespread acceptance. We investigated the shorter living positron emitting 55Co (half-life 18.2 h) as a level for bleomycin. In eleven patients with proven lung cancer scintigraphy with 55Co-bleomycin, using a positron camera, demonstrated the tumor in ten cases. Tumor to lung ratios were calculated. The results were superior to those obtained with 55Co-bleomycin single photon imaging but inferior to those obtained with 57Co-bleomycin scintigraphy.
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