There is a good bit of info on the BBB transport systems at
http://jn.nutrition.org/cgi/content/...ct/130/4/1016S
Note that the full text is free too.
One problem not addressed in the BBB idea is the work by Kraak showing transport inside the neurons themselves from nose and stomach. Such movement would presumably bypass the BBB altogether.
I think we make a fundamental mistake when we assume that there is a single cause for PD. It is quite possible that several factors exist that could combine in different configurations to produce similar results. This could account for the "alike yet different" nature of our common curse.
Finally, in terms of explaining the observed data, this does a decent job
http://neurotalk.psychcentral.com/sh...ght=endotoxins