SARATOGA SPRINGS, N.Y. – Jackson Bend served notice he’d be a force to be reckoned with in the sprint division a year ago with his rail-skimming, 2 1/2-length victory in the James Marvin Stakes. On Friday, Jackson Bend will attempt to defend his title and regain his standing as one of the country’s elite sprinters when topping a field of seven entered in the $100,000 James Marvin, a race elevated to Grade 3 status for the first time this summer.