Nitric oxide and oxygen radicals induced apoptosis via bcl-2 and p53 pathway in hypoxia-reoxygenated cardiomyocytes

Cerebral ischemia and neuroregeneration

Cerebral ischemia is one of the leading causes of morbidity and mortality worldwide. Although stroke (a form of cerebral ischemia)-related costs are expected to reach 240.67 billion dollars by 2030, options for treatment against cerebral ischemia/stroke are limited. All therapies except anti-thrombolytics (i.e., tissue plasminogen activator) and hypothermia have failed to reduce neuronal injury, neurological deficits, and mortality rates following cerebral ischemia, which suggests that development of novel therapies against stroke/cerebral ischemia are urgently needed. Here, we discuss the possible mechanism(s) underlying cerebral ischemia-induced brain injury, as well as current and future novel therapies (i.e., growth factors, nicotinamide adenine dinucleotide, melatonin, resveratrol, protein kinase C isozymes, pifithrin, hypothermia, fatty acids, sympathoplegic drugs, and stem cells) as it relates to cerebral ischemia.

Ischemia-reperfusion injury in stroke

Despite ongoing advances in stroke imaging and treatment, ischemic and hemorrhagic stroke continue to debilitate patients with devastating outcomes at both the personal and societal levels. While the ultimate goal of therapy in ischemic stroke is geared towards restoration of blood flow, even when mitigation of initial tissue hypoxia is successful, exacerbation of tissue injury may occur in the form of cell death, or alternatively, hemorrhagic transformation of reperfused tissue. Animal models have extensively demonstrated the concept of reperfusion injury at the molecular and cellular levels, yet no study has quantified this effect in stroke patients. These preclinical models have also demonstrated the success of a wide array of neuroprotective strategies at lessening the deleterious effects of reperfusion injury. Serial multimodal imaging may provide a framework for developing therapies for reperfusion injury.

Reactive oxygen species and ischemic cerebrovascular disease

Stroke is an emerging major health problem often resulting in death or disability. Hyperlipidemia, high blood pressure and diabetes are well established risk factors. Endothelial dysfunction associated with these risk factors underlies pathological processes leading to atherogenesis and cerebral ischemic injury. While mechanisms of disease are complex, endothelial dysfunction involves decreased nitric oxide (NO) and elevated levels of reactive oxygen species (ROS). At physiological levels, ROS participate in regulation of cellular metabolism. However, when ROS increase to toxic levels through imbalance of production and neutralization by antioxidant enzymes, they cause cellular injury in the form of lipid peroxidation, protein oxidation and DNA damage. Central nervous system cells are more vulnerable to ROS toxicity due to their inherent higher oxidative metabolism and less antioxidant enzymes, as well as higher content of membranous fatty acids. During ischemic stroke, ROS concentration rises from normal low levels to a peak point during reperfusion possibly underlying apoptosis or cellular necrosis. Clinical trials and animal studies have shown that natural compounds can reduce oxidative stress due to excessive ROS through their antioxidant properties. With further study, we may be able to incorporate these compounds into clinical use with potential efficacy for both the treatment and prevention of stroke.