  The $\sigma$-$\omega$ model of nuclei is studied at leading order in the
$1/N$ expansion thereby introducing the self consistent Hartree approximation,
the Dirac sea corrections and the one fermion loop meson self energies in a
unified way. For simplicity, the Dirac sea is further treated within a
semiclassical expansion to all orders. The well-known Landau pole vacuum
instability appearing in this kind of theories is removed by means of a scheme
recently proposed in this context. The effect of such removal on the low
momentum effective parameters of the model, relevant to describe nuclear matter
and finite nuclei, is analyzed. The one fermion loop meson self energies are
found to have a sizeable contribution to these parameters. However, such
contribution turns out to come mostly from the Landau poles and is thus
spurious. We conclude that the fermionic loop can only be introduced
consistently in the $\sigma$-$\omega$ nuclear model if the Landau pole problem
is dealt with properly.
