Jamill Kelly  (Colorado Springs, Colo./Gator WC) won a silver medal at 66 kg/145.5 lbs., the only U.S. medalist at the respected Medved International Championships in Minsk, Belarus, March 30-31.    After winning his pool with two wins, Kelly claimed two more victories to qualify for the gold-medal finals. He defeated Tuyakun Buranov of Uzbekistan, 3-1 in the quarterfinals. In the semifinals, Kelly edged Vrangzi Lulzim of Macedonia, 3-2.    Kelly was defeated in the gold-medal finals by Akhmet Yusupov of Russia, 7-3. It was the best performance of Kelly's career at a major international wrestling meet.    Two U.S. wrestlers won their pools, but were defeated in the quarterfinals to finish seventh: Mike Mena (Bloomington, Ind./NYAC) at 55 kg/121 lbs.,  and Byron Tucker, Norman, Okla. (Sunkist Kids) at 74 kg/163 lbs.     Tucker won his match in the round of 16, stopping Radoslav Horbik of Poland, 3-0. In the quarterfinals, he lost by pin to Kurman Remrezov of Russia in 5:46. Tucker is currently ranked No. 2 on the Freestyle Team USA.    Mena was beaten in the quarterfinals by international veteran Nurdin Donbaev of Kyrgyzstan, 3-0, in overtime at 8:56.    Daniel Cormier (Stillwater, Okla./Gator WC) defeated veteran Rolf Sherrer of Switzerland, 10-1 in his opening match at 96 kg/211.5 lbs., but lost his second match by injury default with an arm injury.    Also eliminated in their pool competitions were Danny Felix (Norman, Okla./Sunkist Kids) at 60 kg/130 lbs., Aaron Simpson (Tempe, Ariz./Sunkist Kids) at 84 kg/185 lbs. and Markus Mollica (Boston, Mass./Dave SchultzWC) at 84 kg/185 lbs.     The U.S. team was coached by Mike Duroe of Philadelphia, Pa., the head assistant at the Univ. of Pennsylvania and a former USA Wrestling national freestyle coach, and Troy Steiner of Madison, Wis., a former Team USA athlete.