No abstract

Permeability coefficients of human umbilical vein endothelial cell monolayers cultured on polycarbonate filters were determined by monitoring transendothelial albumin transport. Permeability was determined as a function of time in culture and in the presence of vasoactive agonists. Permeability decreased with increasing time in culture. All agonist experiments were performed with 15-day cultures because this time point best modeled the in vivo permeability barrier function. Permeability of endothelial monolayers decreased significantly in the presence of the stable prostacyclin analogue iloprost (6 nM), dibutyryl adenosine 3',5'-cyclic monophosphate (cAMP, 0.5 mM)-3-isobutyl-1-methylxanthine (IBMX, 0.1 mM), 8-bromo cAMP (0.5 mM)-IBMX, dibutyryl cAMP-theophylline (0.5 mM), or IBMX. A 9.6-fold increase in permeability resulting from thrombin [0.15 U/ml (1 nM)] treatment was inhibited by pretreating the monolayers with dibutyryl cAMP-IBMX, 8-bromo cAMP-IBMX, dibutyryl cAMP-theophylline, dibutyryl cAMP, IBMX, iloprost, or D-Phe-Pro-Arg-CH2-alpha-thrombin (1 nM). The thrombin-induced permeability increase was not significantly altered by pretreating monolayers with aspirin (5 microM) or indomethacin (50 microM). Inactivated forms of thrombin, diisopropylflurophosphate-alpha-thrombin (1 nM) and D-Phe-Pro-Arg-CH2-alpha-thrombin, did not significantly affect permeability. Monolayer permeability was not altered in response to bradykinin (1 microM). These results suggest a mediating role for intracellular cAMP in the permeability barrier function of endothelial monolayers.

No abstract

Elion (1924) was the first to isolate a thermophilic sulfate reducing bacterium in pure culture. He named the organism Vibrio thermodesulfuricans, and reported that it was capable of sulfate reduction betveen 30 and 65 C, wvith an optimum of 55 C. Baars (1930) and Kluyver and Baars (1932) reisolated V. thermodesulfuricans, and carried out a comparative study of this organism and Vibrio desulfuricans. They reported that it was possible to adapt cultures of V. desulfuricans, initially capable of growth only at 30 C, to grow up to 55 C by gradually increasing the incubation temperature. The reverse phenomenon was also demonstrated with V. thermodesulfuricans. They concluded that V. thermodesulfuricans should be regarded as a temperature adapted strain of V. desulfuricans. The sulfate reducing bacteria are now placed in the genus Desulfovibrio, created by Kluyver and Van Niel (1936). Starkey (1938) isolated cultures from sewage, mud, and soil at 30 and 55 C. Contrary to the findings of earlier investigators, all of the cultures isolated at 55 C were large, slightlv curved,

No abstract

No abstract

No abstract

No abstract