Quantification and interpretation of nitric oxide-dependent cutaneous vasodilation during local heating.

Human cutaneous microdialysis approaches for assessing nitric oxide (NO)-dependent blood flow include local heating (LH) of the skin until a plateau is reached, followed by infusion of a NO synthase inhibitor such as -nitro-l-arginine methyl ester (l-NAME); however, varied methods of quantifying and expressing NO-dependent vasodilation can obfuscate data interpretation and reproducibility. We retrospectively assessed NO-dependent vasodilation during LH to 39°C or 42°C, calculated as the ) absolute contribution of the NO-dependent component (along with baseline and the non-NO-dependent component) to the total cutaneous vascular conductance (CVC) response to LH, normalized to maximal CVC (%CVC); ) difference in %CVC (Δ%CVC) between the LH plateau and post-NO synthase inhibition (l-NAME plateau; Δ%CVC = LH plateau - l-NAME plateau); ) percentage of the LH plateau attributable to Δ%CVC (%plateau = Δ%CVC/LH plateau × 100); and ) %plateau when correcting for baseline. The LH plateaus during 39°C and 42°C were 48 ± 17%CVC (9 ± 5% baseline; 2 ± 4% non-NO dependent; 36 ± 15% NO dependent) and 88 ± 10%CVC (15 ± 8% baseline; 9 ± 10% non-NO dependent; 64 ± 13% NO dependent), respectively.

Mapping dominant-negative mutations of anthrax protective antigen by scanning mutagenesis.

The protective antigen (PA) moiety of anthrax toxin transports edema factor and lethal factor to the cytosol of mammalian cells by a mechanism that depends on its ability to oligomerize and form pores in the endosomal membrane. Previously, some mutated forms of PA, designated dominant negative (DN), were found to coassemble with wild-type PA and generate defective heptameric pore-precursors (prepores). Prepores containing DN-PA are impaired in pore formation and in translocating edema factor and lethal factor across the endosomal membrane.