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Background and Purpose: We examined the efficacy of the antioxidant LY231617 administered five hours following middle cerebral artery (MCA) occlusion in rats. Methods: The treatment was contrived for a two hour interval. Group A (n=16) was left untreated. Group B (n=16) received an intravenous infusion of LY231617. Group C (n=6) received saline (86 μI/min) by retrograde infusion of the cerebral vein (RICV). Group D (n=22) was administered LY231617 (10mg/kg/2hr) in saline (86μI/min) by RICV. Local cerebral blood flow with [14C]-iodoantipyrine and blood-brain transfer constant with 14C-α-amino-isobutyric acid were examined. Early ischemic damage was histologically examined with cresyl violet and Luxol fast blue and with triphenyl-tetrazolium chloride. Results: The results revealed a marked increase in local cerebral blood flow (over 600%, p < 0.01) after RICV with LY231617, with a significant improvement of BBB permeability in rats from group D. Ischemic brain damage measured with Luxol fast blue and triphenyl-tetrazolium chloride methods showed a significant improvement (50-91 %) of ischemic damage in group D, as compared to groups B and C. Conclusion: Retrograde infusion of the cerebral vein with LY231617 resulted in a significant amelioration at seven hours post MCA occlusion.
Formation of supercooled water and frazil ice was studied in the Chukchi Sea coastal polynya off Barrow, Alaska, USA, in winter 2009/10, using moored salinity/temperature sensors and Ice Profiling Sonar (IPS) data along with satellite data. Oceanographic data from two moorings revealed episodic events of potential supercooling at 30–40m depth, including the possibility of in situ supercooling, while the polynya was open. We identified frazil ice-like signals in the IPS data down to 5–15 m depth, associated with large heat loss and windy, turbulent conditions in an active polynya. This likely represents the first IPS observation of frazil ice in the marine environment. On the day of the maximum signal of frazil ice, spaceborne synthetic aperture radar shows streaks of high backscatter within the polynya, indicating active frazil ice formation just downwind of the mooring sites. In addition, the longer-term potential supercooling that persisted for 1–3 weeks occurred twice despite the absence of polynya activity at the mooring sites. These events occurred during periods dominated by the northeastward current. A series of coastal polynyas had formed southwest of the mooring sites prior to these events. Thus, the water masses with potential supercooling were likely advected from these polynyas.