China files trade case against United States Published September 18, 2012 - 12:05am By JOE McDONALDAssociated PressBEIJING ??? China filed a World Trade Organization case Monday challenging U.S. anti-dumping measures on billions of dollars of kitchen appliances, paper and other goods, adding to worsening trade strains as global demand weakens.Beijing???s move came shortly before the Obama administ