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Asthma is one of the leading causes of childhood hospitalization, and its incidence is on the rise throughout the world. Currently, the standard treatment for asthma is the use of corticosteroids to try to suppress the inflammatory reaction taking place in the bronchial tree. Using a murine model of atopic allergic asthma employing a methacholine-hyperresponsive (A/J) as well as a hyporesponsive (C57BL/6) strain of mice sensitized and challenged with ovalbumin, we show that treatment with a synthetic Toll-like receptor 7 (TLR7) ligand (S-28463, a member of the imidazoquinoline family) prevents development of the asthmatic phenotype. Treatment with S-28463 resulted in a reduction of airway resistance and elastance following ovalbumin sensitization and challenge. This was accompanied by a dramatic reduction in infiltration of leukocytes, especially eosinophils, into the lungs of both C57BL/6 and A/J mice following OVA challenge. Treatment with S-28463 also abolished both the elevation in serum IgE level as well as the induction of IL-4, IL-5, and IL-13 by OVA challenge. The protective effects of S-28463 were also observed in MK2 knockout, but not MYD88 knockout, mice. We did not observe a switch in cytokine profile from [T.sub.H]2 to [T.sub.H]1, as both 1L-12p70 and IFN-[gamma] levels were reduced following S-28463 treatment. These results clearly demonstrate the anti-inflammatory effect of imidazoquinolines in an allergic asthma model as well as the clinical potential of TLR7 ligands in the treatment of allergic diseases. Toll-like receptors; asthma; eosinophils; lung; inflammation; mitogen-activated protein kinase-activated protein-2

We have developed a novel cell culture system that supports the shortening of smooth muscle cells. Primary rat airway smooth muscle cells were plated on an ethanol-fixed, confluent monolayer of homologous smooth muscle cells (homologous cell substrate, HCS). Cells grown on HCS exhibited morphological and functional characteristics consistent with a differentiated phenotype. Cells on HCS were spindle shaped with a well-defined long axis, whereas cells grown on glass were larger and irregularly shaped. Smooth muscle-specific [alpha]-actin immunostained diffusely in cells on HCS, whereas it appeared as stress fibers in cells on glass. Agonists recruited a greater fraction of HCS cells to contract, resulting in greater changes in cell area or length on average, but the maximal capacity of shortening of individual cells was similar between the groups. Unlike cells on glass, cells on HCS shortened to methacholine. HCS was reversible and persisted over several passages. Agonists stimulated intracellular [Ca.sup.2+] oscillations in cells on HCS, whereas they elicited biphasic peak and plateau transients in cells on glass. HCS modulates smooth muscle cell phenotype in vitro. cell contraction; extracellular matrix; intracellular calcium

Inbred Fischer 344 rats display airway hyperresponsiveness (AHR) in vivo compared with the normoresponsive Lewis strain. Fischer AHR has been linked with increased airway smooth muscle (ASM) contraction ex vivo and enhanced ASM cell intracellular [Ca.sup.2+] mobilization in response to serotonin compared with Lewis. To determine the generality of this association, we tested whether bradykinin (BK) also stimulates greater contraction of Fischer airways and greater [Ca.sup.2+] mobilization in Fischer ASM cells. Explants of Fischer intraparenchymal airways constricted faster and to a greater degree in response to BK than Lewis airways. BK also evoked higher [Ca.sup.2+] transients in Fischer than in Lewis ASM cells. ASM cell [B.sub.2] receptor expression was similar between the two strains. BK activated both phosphatidylinositide-specific phospholipase C (PI-PLC) and phosphatidylcholine-specific PLC to mobilize [Ca.sup.2+] in Fischer and Lewis ASM cells. PI-PLC activity, as measured by inositol polyphosphate accumulation, was similar in the two strains. PKC inhibition with GF109203X, Go6973, or Go6983 attenuated BK-mediated [Ca.sup.2+] transients in Fischer cells, whereas GF109203X potentiated while Go6976 and Go6983 did not affect [Ca.sup.2+] transients in Lewis cells. Enhanced [Ca.sup.2+] mobilization in ASM cells can arise from variations in PKC and may be an important component of nonspecific, innate AHR. bradykinin; protein kinase C

Research was conducted to examine the kinetics of silylene insertion into N-H bonds and the mechanism and kinetics of the pyrolysis of dimethylsilylamine. The objective of the study is to provide an insight into the gas phase thermal processes that take place in the reaction of SiH4 and NH3 and higher alkylamines. Comparisons of mechanistic expectations with the product data suggest a more complex reaction system.

The effects of adenosine 3',5'-cyclic monophosphate (cAMP) on serotonin (5-HT)-evoked Ca2+ response was analyzed in cultured rat tracheal smooth muscles (TSM) cells. The levels of intracellular cAMP was elevated after the administration of the adenylyl cyclase activator, forskolin, in cultured rat TSM cells. Forskolin also induced the complete relaxation of the tracheal rings during the sustained phase of 5-HT response in rat TSM cells. Furthermore, the effects of forskolin indicated the role of cyclic guanylic acid-dependent protein kinase in mediating the relaxant effects of cAMP.

Analysis of the receptor subtypes that mediates 5-HT-induced airway responses in the rat by measuring the Ca2+ transients in the tracheal smooth muscle cell reveled that the main type of serotonergic receptor responsible for tracheal contraction is 5-HT(sub 2C) which is directly expressed on smooth muscle cells. The airway Ca2+ acts via 5-HT(sub 2C)-like receptors. This causes Ca2+ release from intracellular stores, followed by Ca2+ influx.