Complex sentence: In late 1989, due to a sudden onset of leukemia, Seckel was forced to abandon the Skeptics, and had to immediately enter the hospital, where his health quickly deteriorated; the Southern California Skeptics had folded some two years prior to this.
Split into simpler sentences: In late 1989, due to a sudden onset of leukemia, Seckel had to immediately enter the hospital, where his health quickly deteriorated. The Southern California Skeptics had folded some two years prior to this.