July 21 (Reuters) - Wall Street’s main indexes opened higher on Wednesday as upbeat quarterly results from companies including Johnson & Johnson and Coca-Cola reignited optimism about the health of corporate America. The Dow Jones Industrial Average rose 45.0 points, or 0.13%, at the open to 34556.96. The S&P 500 rose 8.1 points, or 0.19%, at the open to 4331.13, while the Nasdaq Composite rose 9.9 points, or 0.07%, to 14508.747 at the opening bell. (Reporting by Devik Jain in Bengaluru; Editing by Maju Samuel) Our Standards: The Thomson Reuters Trust Principles.