Improved survival of island flaps after prolonged ischemia by perfusion with superoxide dismutase

Perfusion of rat groin flaps after 10 and 11 hours of complete ischemia with superoxide dismutase, an oxygen free-radical scavenger, significantly improved the survival of these flaps. This finding provides further evidence for the important role that oxygen-derived free radicals play in ischemic injury. The study also demonstrates that while restoration of blood supply alone is not enough to ensure tissue survival after prolonged ischemia, chemical agents can be utilized to achieve viable flaps beyond what was believed to be "a point of no return".     

The interaction of benzhydroxamic acid with horseradish peroxidase and its fluorescent analogs

Horseradish peroxidase (HRP) reconstituted with protoporphyrin IX or zinc protoporphyrin IX binds benzhydroxamic acid with affinities of 1.54 × 10⁴ and 8 × 10²m^?1, respectively. This interaction is competitive with respect to hydrogen donor substrates of peroxidase. The steady-state oxidation of benzhydroxamic acid by HRP was studied by monitoring the disappearance of the hydroxamate function and the formation of nitrite. The inhibition by benzhydroxamic acid of oxidation of HRP substrates may be classified as an inhibition by a competing substrate. In the case of HRP-catalyzed oxidation of ferrocyanide a marked activating effect of benzhydroxamic acid was observed. Mechanisms responsible for this effect are discussed.     

High dietary advanced glycation end products are associated with poorer spatial learning and accelerated Aβ deposition in an Alzheimer mouse model

There is growing evidence of the involvement of advanced glycation end products (AGEs) in the pathogenesis of neurodegenerative processes including Alzheimer's disease (AD) and their function as a seed for the aggregation of Aβ, a hallmark feature of AD. AGEs are formed endogenously and exogenously during heating and irradiation of foods. We here examined the effect of a diet high in AGEs in the context of an irradiated diet on memory, insoluble Aβ₄₂, AGEs levels in hippocampus, on expression of the receptor for AGEs (RAGE), and on oxidative stress in the vasculature. We found that AD‐like model mice on high‐AGE diet due to irradiation had significantly poorer memory, higher hippocampal levels of insoluble Aβ₄₂ and AGEs as well as higher levels of oxidative stress on vascular walls, compared to littermates fed an isocaloric diet. These differences were not due to weight gain. The data were further supported by the overexpression of RAGE, which binds to Aβ₄₂ and regulates its transport across the blood–brain barrier, suggesting a mediating pathway. Because exposure to AGEs can be diminished, these insights provide an important simple noninvasive potential therapeutic strategy for alleviating a major lifestyle‐linked disease epidemic.     

Parallel processes within the 'spot-light' of attention.

Human ability to identify simultaneously two targets in the visual field is severely limited. Previous studies have shown that orientation identification of two targets takes twice the time needed for one target. Here we asked whether this seriality is imposed by the decision requirement of the task or by such stimulus properties as target spatial separation and similarity. Observers had to identify the orientations (vertical vs horizontal) of two Gabor patches presented at random positions. Performance on this double-task experiment was compared with performance on each of the tasks when carried out alone. We varied the spatial separation between the two targets for targets having identical or different spatial-frequencies and found that the orientation of two targets having different frequencies could be identified in parallel when occupying the same spatial position but not when separated in space by 4 deg of visual angle or more. Targets having the same frequency could be identified in parallel even when separated by 8 deg, demonstrating that decision factors do not impose seriality. This result can be taken as evidence for the existence of a grouping process operating prior to orientation identification. This grouping process operates according to classical Gestalt rules (proximity, similarity) and enables parallel attentive processing of large input chunks.