Investigating the Association of Wallerian Degeneration and Diaschisis After Ischemic Stroke With BOLD Cerebrovascular Reactivity.

INTRODUCTION: Wallerian degeneration and diaschisis are considered separate remote entities following ischemic stroke. They may, however, share common neurophysiological denominators, since they are both related to disruption of fiber tracts and brain atrophy over time. Therefore, with advanced multimodal neuroimaging, we investigate Wallerian degeneration and its association with diaschisis. METHODS: In order to determine different characteristics of Wallerian degeneration, we conducted examinations on seventeen patients with chronic unilateral ischemic stroke and persisting large vessel occlusion, conducting high-resolution anatomical magnetic resonance imaging (MRI) and blood oxygenation-level dependent cerebrovascular reactivity (BOLD-CVR) tests, as well as Diamox 15(O)-H2O-PET hemodynamic examinations. Wallerian degeneration was determined using a cerebral peduncle asymmetry index (% difference of volume of ipsilateral and contralateral cerebral peduncle) of more than two standard deviations away from the average of age-matched, healthy subjects (Here a cerebral peduncle asymmetry index > 11%). Diaschisis was derived from BOLD-CVR to assess the presence of ipsilateral thalamus diaschisis and/or crossed cerebellar diaschisis. RESULTS: Wallerian degeneration, found in 8 (47%) subjects, had a strong association with ipsilateral thalamic volume reduction (r 2 = 0.60) and corticospinal-tract involvement of stroke (p < 0.001). It was also associated with ipsilateral thalamic diaschisis (p = 0.021), No cerebral peduncular hemodynamic differences were found in patients with Wallerian degeneration. In particular, no CBF decrease or BOLD-CVR impairment was found. CONCLUSION: We show a strong association between Wallerian degeneration and ipsilateral thalamic diaschisis, indicating a structural pathophysiological relationship.

Seasonal temperature variation and the rate of donor deferral for low hematocrit in the American Red Cross.

BACKGROUND: Hematocrit (Hct) values in healthy adult populations exhibit seasonal variation, with the lowest values occurring in the summer. The extent to which environmental temperature contributes to the seasonal trend in deferral rates for unacceptable Hct in the American Red Cross was further analyzed. STUDY DESIGN AND METHODS: A centralized database of donations during 2002 to 2004, constituting 24.3 million donor presentations, was further characterized. Data on mean monthly temperature in the United States were obtained for the same period from a government agency. Multivariate regression analyses were performed to determine the relationship between Hct deferral rates among blood donors and environmental temperature and donor characteristics. RESULTS: Hct deferral rates were associated with mean monthly temperature in the United States (R(2) = 0.77). The relationship between the Hct deferral rate and environmental temperature was strongest in the region of the country with the highest seasonal variation in temperature, followed by regions with intermediate and low seasonal variation in temperature, respectively. The seasonal pattern in Hct deferral rates occurred in both sexes and across all age groups, with significantly higher Hct deferral rates occurring in June through August compared to other quarters (p < 0.0007). CONCLUSION: There is a significant seasonal pattern in Hct deferral rates that is associated with environmental temperature. The relationship between Hct deferral rates and temperature is strongest in areas of the country with greater temperature variability. The effect of seasonality on Hct deferrals should be taken into account for donor counseling, recruitment, and retention efforts.

Three controlled trials of weight loss with phenylpropanolamine.

A multisite double-blind study was designed to determine the effectiveness of a phenylpropanolamine-caffeine combination in achieving weight loss. Two-hundred and one obese adult patients were divided into three separate groups in which phenylpropanolamine/caffeine was compared with either placebo (6 weeks), mazindol (6 weeks), or diethylpropion (8 weeks). In these clinical trials, phenylpropanolamine/caffeine proved to be as effective as mazindol and diethylpropion and significantly more effective than placebo in achieving weight loss. Overall, phenylpropanolamine/caffeine had fewer side effects than mazindol and diethylpropion. Its use as an effective anorectic agent in the treatment of obesity is reviewed.