Platelet-activating factor (PAF) concentration and PAF acetylhydrolase activity in cerebrospinal fluid of patients with subarachnoid hemorrhage

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Abstract
✓ The authors studied the sequential changes in platelet-activating factor (PAF) and PAF acetylhydrolase in the cerebrospinal fluid (CSF) of patients with subarachnoid hemorrhage (SAH). Levels of PAF in CSF showed a gradual increase after the onset of SAH, with a subsequent decrease. The PAF concentration between 5 and 9 days after SAH was greater in patients with cerebral infarction due to vasospasm than in patients without infarction. Conversely, PAF acetylhydrolase activity decreased gradually after SAH, then increased. The enzyme activity for the same period was smaller in patients with cerebral infarction than in patients without infarction. The distribution of the days of maximum PAF concentration and minimum PAF acetylhydrolase activity did not differ significantly between the two groups. The CSF as a source of PAF acetylhydrolase activity gave an apparent Michaelis constant value of 90.8 µM and a maximum velocity of 0.2 nmol/min/mg. The optimum pH level for the PAF acetylhydrolase activity obtaine...