 SAO PAULOPARIS, June 27 Reuters - Casino Guichard Perrachon on Thursday unveiled a plan to simplify the complex shareholding structure for its Latin American operations, sending shares in its Brazilian and Colombian units soaring. The restructuring would result in Casino controlling its Latin American business in Brazil, Colombia, Uruguay and Argentina through a 41.4 stake in Brazilian unit Grupo Pao de Acucar GPA. Casino, which has been grappling with high debt, has been trying to address investor criticism over the complex and sometimes opaque structure of its business. 