Effect of blocking TNF-α on intracellular BCG (Bacillus Calmette Guerin) growth in human monocyte-derived macrophages

Abstract Four agents, thalidomide, oxpentifylline, dexamethasone and a polyclonal anti-TNF-α antibody, were all shown by specific Elisa to block endogenous TNF-α production by Bacillus Calmette Guerin (BCG)-infected human monocyte-derived macrophages in in vitro culture. There was however no significant enhancement of intracellular BCG growth, over a 7-day incubation, in human monocyte-derived macrophages in the presence of any of the TNF-α-blocking agents, as determined by both radiometric and CFU counting methods of assessing bacterial viability and growth. The result suggests that the action of TNF-α alone is unlikely to be an important effector mechanism in antimycobacterial immunity within human cells.     

Studies on the influence of nitrite on methemoglobin formation in Amazonian fishes

Twenty one species of fishes, collected from the Rio Solim?es and a tributary lake in the Amazon Basin near Manaus, showed a wide range of methemoglobin formation 1 hr after a dose of 30 mg/kg of sodium nitrite i.p. Methemoglobin formation in two experimental fishes, Brycon cf. melanopterum and Semaprochilodus insignis, maintained in tanks in our INPA laboratory, was studied in detail. Both fishes survived a dose of 10 mg/kg of nitrite i.p. but usually died within 3 hr of a dose of 30 mg/kg with levels of blood methemoglobin in excess of 80%. Methemoglobin produced in vitro by addition of nitrite to fresh blood was slowly reduced back to hemoglobin over a period of several hours at room temperature. Hemoglobin in hemolysates was auto-oxidized to methemoglobin at pH 6.1 and below but not at 6.9 and above.     

Patch-clamp experiments with porins extracted from a marine bacterium (Photobacterium profundum strain SS9) and Reconstituted in liposomes

The reconstitution of bacterial porins in liposome bilayers for patch-clamp recording is well established. However, the solutions used in the dehydration, rehydration, and osmotic swelling of the liposomes have been developed for porins from enteric bacteria. Porins from marine bacteria normally function in contat with seawater whose ionic composition and osmotic pressure would appear to be incompatible with the established methods. Here, we show that, contrary to expectation, an established reconstitution and patch-clamp method works well with proins, mainly OmpH and OmpL, extracted from the deep-sea marine bacterium Photobacterium profundum strain SS9 and that seawater can be introduced at a supplementary stage.