This is a summary. To read the whole story subscribe to BostonGlobe.com
American 100-meter record holder Tyson Gay tested positive for a banned substance and said he will pull out of the world championships next month in Moscow. Gay wouldn’t reveal the substance in a phone conversation from Amsterdam on Sunday, but he said he was notified by the US Anti-Doping Agency late last week that a sample came back positive from a May 16 out-of-competition test. He said he will have his ‘‘B'’ sample tested soon, possibly as early as this week. ‘‘I don’t have a sabotage story. I don’t have any lies. I don’t have anything to say to make this seem like it was a mistake or it was on USADA’s hands, someone playing games,’’ said Gay.