BURLINGTON, Vt. (AP) — One of two men charged with bringing drugs to Vermont in exchange for guns they took back to Boston has pleaded not guilty to federal charges. Thirty-four-year-old Darwin Medina entered the plea Tuesday during an appearance before a federal magistrate in Burlington. Prosecutors say Medina and 26-year-old John Guerrero told people in northwestern Vermont they were members of the Latin Kings street gang.