Insight into potential mechanisms of hypobaric hypoxia-induced learning and memory deficit - Lessons from rat studies

Impairment of memory is one of the most frequently reported symptoms during sudden hypoxia exposure in human. Cortical atrophy has been linked to the impaired memory function and is suggested to occur with chronic high-altitude exposure. However, the precise molecular mechanism(s) of hypoxia-induced memory impairment remains an enigma. In this work, we review hypoxia-induced learning and memory deficit in human and rat studies. Based on data from rat studies using different protocols of continuous hypoxia, we try to elicit potential mechanisms of hypobaric hypoxia-induced memory deficit.

Preparation of purified atactic polypropylene and polyvinyl methyl ether surfaces for thrombogenicity studies

Commercial samples of atactic polypropylene (aPP) and polyvinyl methyl ether (PVME) were purified and spin-cast onto glass coverslips with a view to using these as model surfaces in thrombogenicity studies. These materials differ from polyvinyl alcohol (PVA) in a single functional group and are similarly amorphous: with the same backbone they have a hydroxyl, a methoxy, or a methyl group. The objective was to understand the role of the hydroxyl group in the platelet reactivity of PVA. Surface characterization showed that they were chemically pure (as determined by X-ray photoelectron spectroscopy) but not smooth (as determined by scanning electron microscopy or interferometry), presumably due to the difficulties of spin-casting optically clear films from hot solutions (aPP or polyethylene [PE]) or because of imperfect adhesion to the saline-treated substrate (PVME). PVME was also gamma-irradiated to insolubilize it. Fewer platelets adhered to PVA than to PVME or to aPP and PE, but roughness effects and limited data preclude definitive conclusions regarding the effect of functional groups. Less protein was found on PVA than on the hydrophobic surfaces, but the significance of this observation is unclear. Further studies with more sensitive protocols are called for to examine the extent of platelet activation and its relationship to surface chemistry.