Detection of cerebral metabolites in a canine model of ischemic stroke using H magnetic resonance spectroscopy

Proton magnetic resonance spectroscopy (¹H MRS) provides in vivo biochemical information on tissue metabolites. The purpose of this study was to investigate the serial metabolic changes of ¹H MRS in the cerebrum of ischemic dogs. An ischemic stroke was induced in five health laboratory beagle dogs by permanent middle cerebral artery occlusion using a silicone plug. ¹H MRS was serially performed three times with a 1.5-T MR system: before, three days after and 10 days after the stroke. Immunohistochemical staining was performed to determine the expression of neuronal nuclei (NeuN) and glial fibrillary acidic protein (GFAP) at both the ipsilateral and contralateral cerebral cortex. Reduced levels of N-acetyl-asparate (p < 0.05), choline (Cho), creatine (Cr) and myo-inositol (mI), and a marked increase in the lactate (Lac) level (p < 0.01) were found at three days after the stroke. At 10 days after the stroke, the levels of Lac significantly increased (p < 0.01); however, the other metabolites were partially elevated. The changes of Cr, Cho and mI were not statistically significant (p > 0.05) when the before and after stroke values were compared. There was a significant loss of NeuN and GFAP immunoreactivity at the ischemic core. ¹H MRS may be to a useful diagnostic tool for the evaluation of ischemic stroke in dogs.     

A comparative study on grid-based storm runoff prediction using Thiessen and spatially distributed rainfall

The simulated streamflow from Thiessen average rainfall (T) and spatially distributed rainfall (R) may be significantly different from each other. To identify the hydrologic effects quantitatively, the grid-based kinematic wave storm runoff model was adopted. The model predicts temporal and spatial variations of surface and subsurface flow at each cell by calculating the water balance, and routes the streamflow to the outlet. The model was tested at the Yeoncheondam watershed (1,875 km²), one third of which belongs to North Korea. The watershed is elongated to north and south directions crossing the border. Four rain gauges cover the watershed within the territory of South Korea, while no records from North Korea are given. The simulated results showed the large differences in runoff volume and peak flow rates between T and R when rain moves in a north to south direction. The simulated results of east-to-west-direction storms showed little difference in the hydrographs. The hydrograph was strongly affected by the spatial variations of the rainfall moving along the stream of the watershed.     

Influence mechanism of climate change on paddy farming practices and irrigation water demand

Paddy and Water Environment - Technological and socioeconomic interventions accompanied by climate warming strongly dictate farming practices, lending a direct impact over future irrigation water...