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  • Author or Editor: Christopher R. Honey x
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Ming-Chieh Sun, Christopher R. Honey, Caglar Berk, Norman L. M. Wong and Joseph K. C. Tsui

Object. Aquaporin-4 (AQP4) plays a significant role in the regulation of brain water homeostasis. In this study the authors investigated the regulation of AQP4 following a focal cortical contusion injury in rats.

Methods. Thirty-three adult male Wistar rats received a focal cortical contusion of the parietal cortex. An additional nine rats underwent a craniectomy, but no trauma was inflicted (sham injury). Animals were killed 1, 4, and 24 hours later. The rat brains were examined for water content by comparing the wet and dry weights of each hemisphere. Aquaporin-4 messenger (m)RNA was measured by reverse transcription—polymerase chain reaction. A ratio of AQP4 mRNA expression in the lesioned hemisphere compared with that in the contralateral control hemisphere was calculated for each animal at the injury site (parietal cortex) and at sites adjacent to (occipital cortex) and distant from the injury (frontal pole cortex).

Brain edema was significantly increased at the injury site. The expression of AQP4 mRNA was significantly increased at the injury site, significantly decreased adjacent to the injury site, and not significantly different at a site distant from the injury. The magnitude of AQP4 mRNA upregulation at the injured parietal cortex correlated with the degree of downregulation in the adjacent occipital cortex.

Conclusions. Data from this study demonstrate that an upregulation of AQP4 occurs at the site of traumatic brain injury and that a downregulation of this molecule occurs adjacent to the site of injury. Understanding the physiology of AQP4 and its regulation following brain injury may allow for the development of novel treatments for cerebral edema that accompanies head injury.

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Christopher R. Honey, A. Jon Stoessl, Joseph K. C. Tsui, Michael Schulzer and Donald B. Calne

Object. The goal of this study was to determine whether unilateral pallidotomy reduces parkinsonian pain.

Methods. Twenty-one patients suffering from Parkinson's disease (PD) were followed prospectively for 1 year after they had undergone a unilateral pallidotomy to assess the procedure's effect on pain related to PD. Pain unrelated to PD was not studied. Patients scored the level of their PD pain on an ordinal scale (0–10 points) preoperatively and 6 weeks and 1 year postoperatively. The results were analyzed using Wilcoxon's paired-ranks test (with Bonferroni correction) and showed a significant reduction in overall pain scores at 6 weeks (p < 0.001) and 1 year (p = 0.001) following pallidotomy. Various types of PD pain are described and their possible pathophysiological mechanisms are presented.

Conclusions. Unilateral pallidotomy significantly reduces pain attributable to Parkinson's disease.