Proceedings of the American Thoracic Society
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The resolution of alveolar edema is regulated by active sodium and chloride transport across the pulmonary epithelium, including alveolar epithelial type I and II cells as well as distal airway epithelia. Catecholamine-dependent mechanisms can markedly upregulate alveolar fluid clearance even under pathological conditions, an effect that is mediated by both epithelial sodium channel (ENaC) and cystic fibrosis transmembrane conductance regulator (CFTR). ⋯ However, there is some experimental and clinical evidence that cAMP stimulation could accelerate the resolution of pulmonary edema in the presence of acute lung injury. Clinical trials are needed to test this potential therapeutic strategy in patients with acute lung injury.
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The variety of pulmonary infections encountered in HIV-infected individuals indicates that many components of the host defense network are impaired. In addition to depletion of CD4+ T cell numbers, HIV infection results in functional deficits in CD4+ T cells, CD8+ T cells, and natural killer cells. ⋯ There are few data examining the functional capabilities of neutrophils in the lung, but evidence from peripheral blood neutrophils indicates that defense by these cells is also impaired. An improved understanding of these events in the lung during HIV infection could lead to specific interventions aimed at restoration of deficient function.
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The study of lung mechanics has progressed from global descriptions of lung pressure and volume relationships to the high-resolution, three-dimensional, quantitative measurement of dynamic regional mechanical properties and displacements. X-ray computed tomography (CT) imaging is ideally suited to the study of regional lung mechanics in intact subjects because of its high spatial and temporal resolution, correlation of functional data with anatomic detail, increasing volumetric data acquisition, and the unique relationship between CT density and lung air content. This review presents an overview of CT measurement principles and limitations for the study of regional mechanics, reviews some of the early work that set the stage for modern imaging approaches and impacted the understanding and management of patients with acute lung injury, and presents evolving novel approaches for the analysis and application of dynamic volumetric lung image data.
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Smoking is a major cause of chronic obstructive pulmonary disease (COPD) and cardiovascular disorders, including coronary heart disease (CHD) and peripheral arterial disease. Smoking-induced inflammation and other risk factors like dyslipidemia cause vascular endothelial damage via oxidative stress, and a vicious cycle with the characteristics of atherosclerosis ensues. Inflammatory cytokines stimulate hepatic acute-phase protein production, and C-reactive protein is now used widely to assess inflammation in the arterial wall. ⋯ The 3-hydroxy-3-methylglutaryl coenzyme-A reductase inhibitors (statins) are used widely to treat and prevent cardiovascular disease. The statins may also produce other beneficial pleiotropic effects, including increased nitric oxide and prostacyclin, antithrombosis, and decreased inflammation, perhaps indicating utility in the therapy for COPD. Efforts are currently underway to determine if such antiinflammatory effects are independent of or in addition to simply lowering low-density lipoprotein cholesterol.