Molsidomine for the prevention of vasospasm-related delayed ischemic neurological deficits and delayed brain infarction and the improvement of clinical outcome after subarachnoid hemorrhage: a single-center clinical observational study

OBJECT Delayed ischemic neurological deficits (DINDs) and cerebral vasospasm (CVS) are responsible fora poor outcome in patients with aneurysmal subarachnoid hemorrhage (SAH), most likely because of a decreased availability of nitric oxide (NO) in the cerebral microcirculation. In this study, the authors examined the effects of treatment with the NO donor molsidomine with regard to decreasing the incidence of spasm-related delayed brain infarctions and improving clinical outcome in patients with SAH. METHODS Seventy-four patients with spontaneous aneurysmal SAH were included in this post hoc analysis. Twenty-nine patients with SAH and proven CVS received molsidomine in addition to oral or intravenous nimodipine. Control groups consisted of 25 SAH patients with proven vasospasm and 20 SAH patients without. These patients received nimodipine therapy alone. Cranial computed tomography (CCT) before and after treatment was analyzed for CVS-related infarcts. A modified National Institutes of Health Stroke Scale (mNIHSS) and the modified Rankin Scale (mRS) were used to assess outcomes at a 3-month clinical follow-up. RESULTS Four of the 29 (13.8%) patients receiving molsidomine plus nimodipine and 22 of the 45 (48%) patients receiving nimodipine therapy alone developed vasospasm-associated brain infarcts (p < 0.01). Follow-up revealed a median mNIHSS score of 3.0 and a median mRS score of 2.5 in the molsidomine group compared with scores of 11.5 and 5.0, respectively, in the nimodipine group with CVS (p < 0.001). One patient in the molsidomine treatment group died, and 12 patients in the standard care group died (p < 0.01). CONCLUSIONS In this post hoc analysis, patients with CVS who were treated with intravenous molsidomine had a significant improvement in clinical outcome and less cerebral infarction. Molsidomine offers a promising therapeutic option in patients with severe SAH and CVS and should be assessed in a prospective study.

Statins as regulators of redox signaling in platelets

SIGNIFICANCE

Reactive oxidant species (ROS) are highly reactive molecules produced by several cell lines including platelets and serve as second messenger for intracellular signaling. In recent years it became evident that ROS are also implicated in the thrombotic process. Statins are lipid lowering molecules which reduce serum cholesterol and retard atherosclerotic complication and its clinical sequelae. However there is evidence that statins may exert an antiplatelet effects by interfering with redox signaling.

RECENT ADVANCES

Experimental and clinical studies provided evidence that intra-platelet ROS formation is implicated in the process of thrombosis, as impaired ROS neutralization is associated with serious thrombotic complication and eventually death. Recent studies demonstrated that statins possess antiplatelet activity via inhibition of platelet NADPH oxidase-derived ROS formation. This effect results in down-regulation of isoprostanes, which are pro-aggregating molecules, and up-regulation of nitric oxide, which is a platelet inhibitor; such changes occurred immediately after statin's administration and were independent from lipid lowering property.

CRITICAL ISSUES

Experimental and clinical studies documented that statins possess an antithrombotic effects which may account for thrombotic-related vascular outcomes. This has been evidenced in clinical settings such as percutaneous coronary intervention, myocardial infarction and venous thrombosis. It is still unclear, however, if the statin's antithrombotic effect is dose-related.

FUTURE DIRECTIONS

Future studies should be addressed to analyze if the antiplatelet effect of statins may preferentially occur at high dosage of statins. Furthermore, the antiplatelet effects of statins could turn useful in clinical settings where the clinical efficacy of aspirin and other antiplatelet drugs are still uncertain.

Selective opening of the blood-tumor barrier by a nitric oxide donor and long-term survival in rats with C6 gliomas

OBJECT

The response of brain tumors to systemic chemotherapy is limited by the blood-tumor barrier (BTB). Nitric oxide (NO) has been implicated in the regulation of vascular permeability and blood flow. The authors evaluated the effects of exogenous NO, which was released from a short-acting NO donor (Proli/NO), and those of NO metabolites on the capillary permeability of tumors and normal brain tissue by using quantitative autoradiography in a C6 glioma model in rats.

METHODS

The Proli/NO was infused at a wide dose range (10(-2) to 10(-12) M) either intravenously or into the internal carotid artery (ICA) and demonstrated substantial tumor-selective increases in blood-brain barrier (BBB) permeability in response to various-sized tracers ([14C]aminoisobutyric acid, [14C]sucrose, [14C]dextran). Internal carotid artery or intravenous administration of sodium nitrite had a comparable effect on BTB permeability. The NO effect on microvascular permeability could be obtained without causing hemodynamic side effects. The effect of NO on the efficacy of carboplatin chemotherapy was investigated in intracerebral C6 gliomas. Simultaneous intravenous infusions of Proli/NO (10(-6) M) and carboplatin (20 mg/kg) led to long-term survival in 40% of rats harboring intracerebral C6 gliomas compared with control animals receiving ICA or intravenous infusions of carboplatin, Proli/NO, or vehicle alone. No residual tumor was demonstrated on histological or magnetic resonance imaging studies performed in rats treated with Proli/NO and carboplatin, and no toxicity was observed.

CONCLUSIONS

This new approach demonstrated the in vivo efficacy and safety of NO and nitrite in enhancing the delivery of systemically delivered radiolabeled tracers and carboplatin into rat gliomas. The NO-induced tumor-selective BBB disruption and intravenous carboplatin chemotherapy may be more efficacious than current chemotherapy strategies against brain tumors.

Neuroprotection by tempol in a model of iron-induced oxidative stress in acute ischemic stroke

Studies suggest iron exacerbates the damage caused by ischemic stroke. Our aim was to elucidate the effect of iron overload on infarct size after middle cerebral artery occlusion (MCAO) and to evaluate the efficacy of tempol, a superoxide dismutase mimetic, as a neuroprotective agent. Rats were administered iron +/- tempol before MCAO; control rats received saline. The middle cerebral artery was occluded for 24 h, and the size of the resultant infarct was assessed and expressed as the percentage of the hemisphere infracted (%HI). Iron treatment increased infarct size compared with control (51.83 +/- 3.55 vs. 27.56 +/- 3.28%HI iron treated vs. control, P = 0.01); pretreatment with tempol reversed this (51.83 +/- 3.55 vs. 26.09 +/- 9.57%HI iron treated vs. iron + tempol treated, P = 0.02). We hypothesized that reactive oxygen species (ROS) were responsible for the iron-induced damage. We measured ROS generated by exogenous iron in brain and peripheral vasculature from rats that had not undergone MCAO. There was no increase in ROS production in the brain of iron-treated rats or in brain slices incubated with iron citrate. However, ROS generation in carotid arteries incubated with iron citrate was significantly increased. ROS generation from the brain was assessed after MCAO by dihydroethidine staining; there was a dramatic increase in the ROS generation by the brain in the iron-treated rats compared with control 30 min after MCAO. We propose that iron-induced ROS generation in the cerebral vasculature adds to oxidative stress during an ischemic episode after the disruption of the blood-brain barrier.

Neuroprotection by the stable nitroxide 3-carbamoyl-proxyl during reperfusion in a rat model of transient focal ischemia

OBJECT

Nitroxides mimic superoxide dismutase (SOD) biochemically and may prevent free radical oxidative injury in settings in which endogenous SOD is overwhelmed. The authors have previously shown the efficacy of a nitroxide, Tempol, in reducing stroke infarct size. Of the nitroxides, 3-carbamoyl-proxyl (3-CP) is especially promising for clinical use, because it does not cause hypotension in animals. Its efficacy in brain ischemia, however, is untested. The goal of this study was to ascertain whether 3-CP would reduce brain damage in a rat ischemia-reperfusion model.

METHODS

The authors performed a blinded, dose-response study of the effect of different amounts of 3-CP (1, 10, and 100 mg/kg) on infarct size at 24 hours after focal ischemia and reperfusion. The 3-CP was given intravenously during reperfusion, which followed 1 hour of reversible ischemia induced by a thread placed intraluminally in the middle cerebral artery of rats. Brain infarcts, measured with 2,3,5-triphenyltetrazolium chloride staining in six 3-CP groups, were compared with those measured in controls (animals given an equal volume of saline). Edema-corrected infarct sizes (mean +/- standard deviation) were as follows: 146 +/- 64 mm3 in controls; 107 +/- 18 mm3 in rats given 1 mg/kg 3-CP; 40 +/- 20 mm3 in those given 10 mg/kg 3-CP; and 44 +/- 17 mm3 in those given 100 mg/kg 3-CP. A statistically significant reduction in infarct size was achieved in the 10- and 100-mg/kg 3-CP-treated groups (p < 0.01). A reduction in infarct size was also seen in the 1 mg/kg 3-CP-treated group, but this did not reach statistical significance. The authors observed no effects of 3-CP on blood pressure or brain temperature.

CONCLUSIONS

Given at reperfusion, 3-CP significantly decreases brain infarct size at doses of 10 and 100 mg/kg without causing hypotension. The authors found that 3-CP is well suited for further laboratory and clinical use in brain ischemia and reperfusion.