H.J. Heinz announced it will eliminate 600 jobs across North America, including about 350 in Pittsburgh. That represents nearly a third of employees in the city where the company is headquartered. Warren Buffett's Berkshire Hathaway and Brazilian firm 3G capital purchased Heinz in June in a deal worth $23.3 billion, and a spokesman says the layoffs were a result of an efficiency review undertaken at that time.