The presence of simultaneous head and neck squamous cell carcinoma and pulmonary malignancies should not be a deterrent to aggressive surgical therapy because a potentially satisfactory outcome can be expected in these patients.

Cartilage production and activity of MMP after injury to the large conducting airway may be a factor in the failure of luminal reepithelialization, resulting in aberrant repair.

There are two major transport pathways across epithelia: a transcellular pathway through cells and a paracellular pathway between cells. Previous electrophysiological studies in mosquito Malpighian tubules suggested that the neuropeptide leucokinin-VIII (LK-VIII) increases the chloride permeability of the paracellular pathway. To test the effect of LK-VIII on the paracellular pathway further, we measured transepithelial permeabilities of inulin and sucrose in isolated Malpighian tubules from the mosquito Aedes aegypti. Cell membranes are impermeable to inulin and sucrose, leaving the paracellular pathway as the only route for their transepithelial permeation. LK-VIII (10(-6) mol l-1) significantly increased transepithelial permeability to both inulin (by 73.8 %) and sucrose (by 32.4 %) in parallel with a significant increase in rates of transepithelial fluid secretion (by 75­90 %). Cyclic adenosine monophosphate (cyclic AMP, 10(-4) mol l-1), which is known to stimulate transcellular transport, also increased rates of transepithelial fluid secretion (by 57­59 %), but it did so without increasing the permeability to sucrose and inulin. Thus, LK-VIII increases the permeability of the paracellular pathway whereas cyclic AMP does not.

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