  Here we continue to elaborate properties of the relativistic mean-field based
model (SHMC) proposed in ref. [6] where hadron masses and coupling constants
depend on the $\sigma$-meson field. The validity of approximations used in [6]
is discussed. We additionally incorporate contribution of meson excitations to
the equations of motion. We also estimate the effects of the particle width. It
is demonstrated that the inclusion of the baryon-baryon hole and
baryon-antibaryon loop terms, if performed perturbatively, destroys the
consistency of the model.
