Barbara Raskob of The Kaufman Org., which specializes in leasing and managing office space in New York City, recently brokered four leases totaling 8,042 square feet at the Nelson Tower, located at 450 Seventh Ave. Asking prices for all transactions ranged from the mid-to-upper $40s per s/f. Raskob represented the landlord, the Kaufman Organization, in the following Nelson Tower transactions. Oprea Design Group, Inc., signed a five-year lease, expanding its total space to 1,055 s/f. SiTV, a 24-hour English-language Latino cable network, signed a three-year lease for 2,095 s/f. The tenant now occupies 5,322 s/f. Traffix, Inc., an interactive media company, signed a five-year lease for 1,476 s/f. They now occupy 7,086 s/f. Vintage Real Estate Services, Ltd., a fully-integrated real estate operations and investment firm and The Lovett Company, LLC, a real estate management company, signed a seven-year lease expanding to 3,416 s/f. 450 Seventh Ave., features 24-hour, 7 day-a-week on-site security and management. Tenants include the Kaufman Management Co., Citibank Real Estate and the Metropolitan Transportation Authority.