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Towards a dynamical network view of brain ischemia and reperfusion. Part III: therapeutic implications

Donald J. DeGracia

The general failure of neuroprotectants in clinical trials of ischemic stroke points to the possibility of a fundamen-tal blind spot in the current conception of ischemic brain injury, the “ischemic cascade”. This is the third in a se-ries of four papers whose purpose is to work towards a revision of the concept of brain ischemia by applying network concepts to develop a bistable model of brain ischemia. Here the bistable model of brain ischemia is compared to the ischemic cascade concept. The core weakness of the ischemic cascade concept is revealed to be its assumption of superposition, or that the elements of the ischemic cascade can be summed as linearly independent events. This assumption leads to a concept of neuroprotection as a subtraction of ostensibly inde-pendent damage events. The bistable model offers a different concept of neuroprotection where the role of in-dividual molecular pathways decreases in relevance with respect to the efficacy of outcome. Network thinking provides a framework for critical assessment of widely-used preclinical experimental approaches. The impor-tance of allometric scaling is also discussed. We illustrate that the bistable model provides a viable alternative to the ischemic cascade as an explanatory framework and as a guide for therapeutic development.