Hyperbaric oxygen promotes neural stem cell proliferation by activating vascular endothelial growth factor/extracellular signal-regulated kinase signaling after traumatic brain injury.

Hyperbaric oxygen (HBO) therapy and neural stem cell (NSC) transplantation can improve traumatic brain injury (TBI) clinically. This study aimed to investigate the mechanism of HBO promoting NSC proliferation and neurological recovery after TBI. Twenty-four Sprague-Dawley rats were divided randomly into three groups: a sham group, a TBI group (constructed using Feeney's free-fall method), and an HBO-treated TBI group. Neurological function was evaluated by Neurological Severity Scores on days 1, 3, and 7, and we found that TBI-induced poor neurological function was improved by HBO. On day 7 after TBI, we observed that TBI promoted NSC proliferation, migration to the lesion area, and the levels of vascular endothelial growth factor (VEGF), VEGFR2, Raf-1, MEK1/2, and phospho-extracellular signal-regulated kinase (ERK) 1/2 protein, which were further boosted by HBO, from immunohistochemistry, immunofluorescence, and Western blot experiments. In vitro, cell injury was applied to NSCs isolated from neonatal Sprague-Dawley rats by the Cell Injury Controller II system. Moreover, data from the BrdU Kit and Western blot showed that in-vitro HBO significantly accelerated NSC proliferation and the levels of proteins related to cell cycle and the VEGF/ERK pathway after cell injury, which was suppressed by the VEGFR2 inhibitor. Taken together, this study indicated that HBO may promote NSC proliferation by activating VEGF/ERK signaling and play a crucial role in neuroprotection after TBI.

Failure of deferoxamine, an iron chelator, to improve outcome after collagenase-induced intracerebral hemorrhage in rats.

Intracerebral hemorrhage (ICH) is a devastating stroke with no clinically proven treatment. Deferoxamine (DFX), an iron chelator, is a promising therapy that lessens edema, mitigates peri-hematoma cell death, and improves behavioral recovery after whole-blood-induced ICH in rodents. In this model, blood is directly injected into the brain, usually into the striatum. This mimics many but not all clinical features of ICH (e.g., there is no spontaneous bleed). Thus, we tested whether DFX improves outcome after collagenase-induced striatal ICH in rats. In the first experiment, 3- and 7-day DFX regimens (100 mg/kg twice per day starting 6 h after ICH), similar to those shown effective in the whole-blood model, were compared to saline treatment. Functional recovery was evaluated from 3 to 28 days with several behavioral tests. Except for one instance, DFX failed to lessen ICH-induced behavioral impairments and it did not lessen brain injury, which averaged 43.5 mm(3) at a 28-day survival. In the second experiment, 3 days of DFX treatment were given starting 0 or 6 h after collagenase infusion. Striatal edema occurred, but it was not affected by either DFX treatment (vs. saline treatment). Therefore, in contrast to studies using the whole-blood model, DFX treatment did not improve outcome in the collagenase model. Our findings, when compared to others, suggest that there are critical differences between these ICH models. Perhaps, the current clinical work with DFX will help identify the more clinically predictive model for future neuroprotection studies.

Ischemic stroke associated with use of an ephedra-free dietary supplement containing synephrine.

In response to concerns regarding the safety of ephedra-containing dietary supplements, manufacturers have marketed "ephedra-free" products. Many of these contain synephrine, a sympathomimetic amine from the plant Citrus aurantium. Synephrine is structurally similar to ephedrine and has vasoconstrictor properties. We describe a 38-year-old patient with ischemic stroke associated with an ephedra-free dietary supplement containing synephrine and caffeine. The patient presented with memory loss and unsteady gait after taking 1 or 2 capsules per day of a dietary supplement (Stacker 2 Ephedra-Free) for 1 week. He had no notable medical history or major atherosclerotic risk factors and took no other medications. Physical examination showed a mildly ataxic gait and substantial Impairment of both concentration and memory. Computed tomography and magnetic resonance Imaging of the brain showed subacute infarctions in the left thalamus and left cerebellum in the distribution of the vertebrobasilar circulation. Other causes of ischemic stroke were evaluated, and findings were unremarkable; a vasospastic origin was considered most likely. The patient was discharged with nearly complete resolution of symptoms. Synephrine, a sympathomimetic amine related to ephedrine, may be associated with Ischemic stroke. Consumers and clinicians need to be Informed about the potential risks of ephedra-free products.