BROCKTON, Mass., April 17---Miss Katherine E. Maguire, 50 years old, heartbroken by the news that her nephew, John E. Maguire, was among those probably lost on the Titanic, was taken violently ill to-night and died within a few moments. She had been in the best of health, apparently, but was much attached to her nephew, and the shock was more than she could bear.