  Density-dependent relations among saturation properties of symmetric nuclear
matter and hyperonic matter, properties of hadron-(strange) quark hybrid stars
are discussed by applying the conserving nonlinear $\sigma$-$\omega$-$\rho$
hadronic mean-field theory. Nonlinear interactions that will be renormalized as
effective coupling constants, effective masses and sources of equations of
motion are constructed self-consistently by maintaining thermodynamic
consistency to the mean-field approximation. The coupling constants expected
from the hadronic mean-field model and SU(6) quark model for the vector
coupling constants are compared; the coupling constants exhibit different
density-dependent results for effective masses and binding energies of
hyperons, properties of hadron and hadron-quark stars. The nonlinear
$\sigma$-$\omega$-$\rho$ hadronic mean-field approximation with or without
vacuum fluctuation corrections and strange quark matter defined by MIT-bag
model are employed to examine properties of hadron-(strange) quark hybrid
stars. We have found that hadron-(strange) quark hybrid stars become more
stable in high density compared to pure hadronic and strange quark stars.
