We show the existence of a high d. c. e. degree d and a low2 c.e. degree a such that d is isolated by a.

By constructing a maximal incomplete d.r.e. degree, the nondensity of the partial order of the d.r.e. degrees is established. An easy modification yields the nondensity of the n-r.e. degrees and of the ω-r.e. degrees.