Thanks for you submissions. They're my favorite so far. Still, I don't think the latest designs are an improvement on the original design. The vasculature in the "lungs" is too much detail. The drop shadow is too trite.
As far as colors go, I don't mind the dark blue and green. Maybe some monochrome dark blue logos would be interesting?
Also, what other font variations other than Futura do you think would work?