{HEAD ~ Such ribozymes} represent {TAIL ~ a new and potentially powerful class} of generally adaptable genetic therapeutics 
represent
{ HEAD ~ Such ribozymes } represent { TAIL ~ a new and potentially powerful class } of generally adaptable genetic therapeutics
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH