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The biochemical anti-herbivore defense of trembling aspen plants. This pattern of expression is consistent with a role of this enzyme in insect defense. A search for potential PPO (Populus tremuloides Michx.) was investigated in a molecular analysis of polyphenol oxidase (PPO; EC A PPO substrates in ethanolic aspen leaf extracts using electron(More)
Xenon-enhanced computerized tomography (CT) is well suited for measurements of cerebral blood flow (CBF) in head-injured patients. Previous studies indicated divergent results on whether inhalation of xenon may cause a clinically relevant increase in intracranial pressure (ICP). The authors employed Xe-enhanced CT/CBF measurements to study the effect of 20(More)
BACKGROUND Stroke incidence has fallen since 1950. Recent trends suggest that stroke incidence may be stabilizing or increasing. We investigated time trends in stroke occurrence and in-hospital morbidity and mortality in the Calgary Health Region. METHODS All patients admitted to hospitals in the Calgary Health Region between 1994 and 2002 with a primary(More)
BACKGROUND Emergency abdominal surgery carries a 15% to 20% short-term mortality rate. Postoperative medical complications are strongly associated with increased mortality. Recent research suggests that timely recognition and effective management of complications may reduce mortality. The aim of the present trial is to evaluate the effect of postoperative(More)
The effects of experimental history on responding under a progressive-ratio schedule of reinforcement were examined. Sixteen pigeons were divided into four equal groups. Groups 1 to 3 were trained to peck a key for food under a fixed-ratio, variable-ratio, or differential-reinforcement-of-low-rate schedule of reinforcement. After training, these pigeons(More)
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