Hurdle effect

Leistner, L. (1978). Hurdle effect and energy saving. In Food Quality and Nutrition (W. K. Downey, ed.), pp. 553-562. Apphed Science, London. 

Although ginsenosides have the basic structure of a steroid, the sugar side chains increase the hydrogen bond count and polar surface area that hurdle effective permeability of these compounds across the membranes. The side chains are prone to degradation via hydrolytic cleavages and deglycosylations. Thus, availability of... 

Leistner L (1978) Hurdle effect and energy saving. In Downey WK (ed) Foodqnality and nutrition. Applied Science Publicatirm, Lrmdrai, p 553... 

One can readily see the intense volume and PMN cost sensitivity over and above this company s own decision criteria of a 10 improvement over existing products before consideration for marketing. Thus, the hurdle level created by PMN costs can be far greater than a company s original decision criterion and the chances for small volume substances being brought forward are reduced. Obviously, with longer product life the effect would be less dramatic but no less real. 

Opsonization by complement components also represents a potential barrier for intravenous gene delivery. Cationic charges of the particles activate the complement, which then takes part in particle elimination. This hurdle is possibly limited by using short hydrophobic chains, reducing the particle size, and eventually PEG insertion into lipoplexes (18). The interaction effect between the lipoplex and the complement might not be such a limitation. Indeed, it was reported that depletion of complement by injection of cobra venom factor and anti-C3 antibodies in mice indicated no differences upon intravenous injection of lipoplexes, neither in terms of tissue distribution nor in lipofection efficiency (19). 

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