Asphalt volcanism and chemosynthetic life in the Campeche Knolls, Gulf of Mexico.

In the Campeche Knolls, in the southern Gulf of Mexico, lava-like flows of solidified asphalt cover more than 1 square kilometer of the rim of a dissected salt dome at a depth of 3000 meters below sea level. Chemosynthetic tubeworms and bivalves colonize the sea floor near the asphalt, which chilled and contracted after discharge. The site also includes oil seeps, gas hydrate deposits, locally anoxic sediments, and slabs of authigenic carbonate. Asphalt volcanism creates a habitat for chemosynthetic life that may be widespread at great depth in the Gulf of Mexico.

Extravasation of leukocytes assessed by intravital microscopy: effect of thalidomide.

OBJECTIVE AND DESIGN: Thalidomide is very effective in the treatment of idiopathic aphthous stomatitis, characterized by recurrent focal intramucosal leukocytic vasculitis. The mode of action of thalidomide in this clinical entity may include inhibition of the extravasation of leukocytes. Therefore, we studied the effect of thalidomide on different steps of leukocyte migration by intravital microscopy. MATERIAL: Male Syrian golden hamsters were used. TREATMENT: Leukocyte migration in buccal mucosa of the hamster cheek pouch was elicited by the local application of lipopolysaccharide (LPS, 20 micrograms/ml) or murine tumor necrosis factor-alpha (muTNF-alpha, 10 ng/ml). (+)-Thalidomide (20-200 mg/kg i.p.) was administered 60 min before the local application of LPS or muTNF-alpha. Dexamethasone (2 x 1.0-10 mg/kg i.p.) was administered 18 h and 60 min before topical LPS application. METHODS: The numbers of rolling, firmly adherent and migrating leukocytes were estimated by intravital microscopy up to 165 min after the topical applications of LPS or muTNF-alpha and evaluated by an interactive image analysis software. RESULTS: Thalidomide (20-200 mg/kg i.p.) dose-dependently inhibited LPS-stimulated perivenular leukocyte migration by up to 87 +/- 5% and muTNF-alpha-induced leukocyte migration by up to 78 +/- 4%. Dexamethasone (2 x 1.0-10 mg/kg i.p.) inhibited LPS-stimulated leukocyte migration by up to 85 +/- 13%. (+)-Thalidomide (200 mg/kg i.p.) inhibited LPS-stimulated rolling by 80 +/- 5% and reduced the number of firmly adherent leukocytes by about 40%. Dexamethasone (2 x 10 mg/kg i.p.) did not reduce the number of rolling leukocytes but inhibited leukocyte adherence by 72 +/- 9%. CONCLUSIONS: These results show that (+)-thalidomide predominantly inhibits leukocyte rolling and thus differs from the glucocorticoid dexamethasone. The inhibition of LPS- or muTNF-alpha-induced leukocyte extravasation by thalidomide may account for some of its clinical activities.