Where did Barry Mc Guigan loose his world boxing title?

In Las Vegas in the hot sun. He was fighting a Latin figher--Mexican I think or perhaps Mexican-American--who could handle the heat and McGuigan couldn't. It was a stupid fight to take at that time of the year--bad management--and his cornermen were inept and panicked. I think he suffered what he felt was genuine damage to his brain and I don't think he ever fought after that.