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Liddle's syndrome is an inherited form of hypertension caused by mutations that truncate the C-terminus of human epithelial Na+ channel (hENaC) subunits. Expression of truncated beta and gamma hENaC subunits increased Na+ current. However, truncation did not alter single-channel conductance or open state probability, suggesting there were more channels in the plasma membrane. Moreover, truncation of the C-terminus of the beta subunit increased apical cell-surface expression of hENaC in a renal epithelium. We identified a conserved motif in the C-terminus of all three subunits that, when mutated, reproduced the effect of Liddle's truncations. Further, both truncation of the C-terminus and mutation of the conserved C-terminal motif increased surface expression of chimeric proteins containing the C-terminus of beta hENaC. Thus, by deleting a conserved motif, Liddle's mutations increase the number of Na+ channels in the apical membrane, which increases renal Na+ absorption and creates a predisposition to hypertension.

The most common cause of cystic fibrosis is a mutation that deletes phenylalanine 508 in cystic fibrosis transmembrane conductance regulator (CFTR). The AF508 protein is misprocessed and degraded rather than traveling to the apical membrane. We used a novel strategy to introduce the AF508 mutation into the mouse CFTR gene. Affected epithelia from homozygous AF508 mice lacked CFTR in the apical membrane and were Cl -impermeable. These abnormalities are the same as those observed in patients with AF508 and suggest that these mice have the same cellular defect. 40% of homozygous AF508 animals survived into adulthood and displayed several abnormalities found in human disease and in CFTR null mice. These animals should provide an excellent model to investigate pathogenesis and to examine therapies directed at correcting the AF508 defect. (J. Clin.

Intravenous sivelestat had no effect on 28-day all-cause mortality or ventilator-free days in a heterogeneous acute lung injury patient population managed with low tidal volume mechanical ventilation.

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Pregabalin demonstrated modest efficacy in pain, global assessment, and function in FM at 450 mg/day, and improved sleep across all dose levels, but it did not provide consistent evidence of benefit at 300 and 600 mg/day in this study. Pregabalin was generally well tolerated for the treatment of FM. (Clinical trial registry NCT00333866).

Further study of the role of NE inhibition as a treatment for ALI is warranted. Additional clinical and preclinical studies with sivelestat and various other NE inhibitors should not only clarify the clinical potential of this intervention strategy, but also better define the activities of NE in inflammatory disorders such as ALI and multiple organ failure.