  We discuss the interpaly between IR and UV divergences in theories with open
and unoriented strings in view of the AdS/CFT correspondence. We start by
deriving general formulas for the computation of threshold corrections to gauge
couplings in generic configurations with open and unoriented strings. These
allow us to discuss the IR/UV correspondence between beta-function coefficients
and ``dilaton'' tadpoles for several brane configurations probed by D3-branes.
Finally we comment on the AdS supergravity descriptions of gauge theories that
are (super)conformal in the large N limit.
