  Band structure calculations are presented for large supercells of
Ba$_2$CuO$_4$ (BCO) with O-vacancies in planar or apic al positions, and of
superoxygenated La$_2$CuO$_4$ (LCO) with oxygen interstitials in the
La$_2$O$_2$ layers. It is foun d that apical oxygen vacancies in BCO act as
electron dopants and makes the electronic structure similar to that of hole
doped LCO. Excess oxygen interstitials forming wires in the La$_2$O$_2$ layers
of LCO are shown to yield a much larger density-of-states at the Fermi energy
than for the stoichiometric compound related with a segmentation of the Fermi
surface. Anti-ferromagnetic (AFM) spin fluctuations are strengthened by
O-vacancies in BCO as well as by oxygen interstitials in LCO, but are strongly
suppressed in O-deficient LCO. Our results indicate the complexity of doping by
O-vacancies, and by ordered defects that are a significant factor contr olling
the electronic properties of cuprates.
