 Complete the following phrase:  Juan Gutiérrez Moreno was a pioneer of the medicine of the Río de la Plata. Towards the 1830s he performs several written works about rabies, and smallpox, two epidemics that had a catastrophic effect in Buenos Aires and Montevideo. In addition to having served in the Hospital Maciel, Gutiérrez had served as a doctor of the Police Department Montevideo. In 1843, he participated in the defense of the city during the 