Browns inside linebacker D’Qwell Jackson missed practice for a second straight day on Thursday.  Jackson is dealing with a sprained ankle, an injury he suffered last Sunday at St. Louis against the Rams.  Head coach Romeo Crennel said that it would be doubtful that Jackson would play this week against Seattle if he’s unable to practice today.  Receiver Joe Jurevicius also missed practice on Thursday as he continues to aid his father who was involved in a car accident last weekend.