FM sonography in diffuse liver disease: prospective assessment and blinded analysis

FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.     

Emergence and persistence of Pseudomonas aeruginosa in the cystic fibrosis airway.

Colonization in the respiratory tracts of cystic fibrosis (CF) patients by mucoid Pseudomonas aeruginosa correlates with the progression of bronchial airway pathology. There is a direct correlation between the incidence of Pseudomonas colonization and age, clinical score, extent of pulmonary disease, severity of radiographic changes, and level of serum immunoglobulins. The central propensity to Pseudomonas colonization in patients with CF is not freely understood, but we discuss the acquisition and persistence of P aeruginosa in the CF airway. Elucidation of pathogenetic mechanisms of CF inflammatory airways disease is the first essential step to initiating novel therapies. It has been difficult to prove that the ability of P aeruginosa to adhere to the respiratory epithelium and provide selective advantage for this gram-negative bacillus over other potential pathogens for infection in the CF airway. However, flexible filaments (pili) extending from the Pseudomonas cell wall are thought to medicate epithelial cell adherence for nonmucoid P aeruginosa, and similarly, the gelatinous exopolysaccharide alginate produced by mucoid variants of P aeruginosa seems to be the adhesive to tracheal cells. Following the signal event of adherence, this bacterial pathogen competes successfully for iron cofactor and multiplies, releasing proteases with broad substrate specificities that dramatically alter the airway antiprotease screen, and the pathogen creates defects in local antibacterial defenses. Lung inflammation in CF is characterized by massive neutrophil infiltration. Although critical to host defense, neutrophils also cause progressive airway damage by release of bioactive lipids, oxygen metabolites, and granule enzymes such as hydrolases, myeloperoxidase (MPO), lysozyme, and neutral serine proteases. The necessarily circumscribed discussion that follows will focus narrowly on the host cell-derived factors (macrophages and neutrophils) proposed as important components in this pathogenetic scheme.