Water White matter

Catalase and glutathione peroxidase provide two important cellular systems for eliminating H202. Catalase, a 56kDa cytosolic hemoprotein homotetramer that can act without a cofactor, although it may bind NAD(P)H, functions as a peroxidase to convert H202 to water. It can be irreversibly inactivated by oxidation and demonstrates decreased activity after ischemia-reperfusion. Catalase is more abundant in astrocytes than in neurons and in white matter than in gray matter, but it can be induced in neurons by neurotrophins. There is substantially less catalase activity in brain than in other tissues, such as liver. 

Human foods that are particularly rich in copper (20 to 400 mg Cu/kg) include oysters, crustaceans, beef and lamb livers, nuts, dried legumes, dried vine and stone fruits, and cocoa (USEPA 1980). In humans, copper is present in every tissue analyzed (Schroeder et al. 1966). A 70-kg human male usually contains 70 to 120 mg of copper (USEPA 1980). The brain cortex usually contains 18% of the total copper, liver 15%, muscle 33%, and the remainder in other tissues — especially the iris and choroid of the eye. Brain gray matter (cortex) has significantly more copper than white matter (cerebellum) copper tends to increase with increasing age in both cortex and cerebellum. In newborns, liver and spleen contain about 50% of the total body burden of copper (USEPA 1980). Liver copper concentrations were usually elevated in people from areas with soft water (Schroeder et al. 1966). Elevated copper concentrations in human livers are also associated with hepatic disease, tuberculosis, hypertension, pneumonia, senile dementia, rheumatic heart disease, and certain types of cancer (Schroeder et al. 1966). 

Returning now to the insoluble residue from the nitric solution, which may still contain sulphate of lead and sulphats of baryte—the solid mattSr may at on oe be tested with a drop of sulphide of ammonium. If lead he present, it will be immediately blackened. If otherwise, then having been well washed with water, it may be boiled with pure carbonate of potassa, the solution filtered, excess of alkaline earbonats in the liquid expelled by pure hydro chloric acid, and afterwards chloride of barium added to detect tho presence of sulphuric acid.. If a white precipitate is observed, then the white matter left on the filter is carefully washed and dissolved in a small portion of pure hydrochloric arid to this liquid dilute sulphuric acid is next added, and a prceipltuts of sulphats of baryta is obtained.. ... 

Rinse the sample thoroughly (>12 h) in water and process for paraffin embedding (dehydrate through at ethanol series and then to xylene, do not allow nervous system samples to sit longer than necessary in ethanol or white matter tracts will look like Swiss cheese). 

Kuroiwa T, Nagaoka T, Ueki M, Yamada I, Miyasaka N, Akimoto H (1998) Different apparent diffusion coefficient water content correlations of gray and white matter during early ischemia. Stroke 29 859-865... 

Moseley ME, Butts K, Yenari MA, de Crespigny A (1995) Clinical aspects of DWI. NMR Biomed 8 387-396 Mukherjee P, Bahn MM, McKinstry RC, Shimony JS, Cull TS, Akbudak E, Snyder AZ, Conturo TE (2000) Differences between gray matter and white matter water diffusion in stroke diffusion-tensor MR imaging in 12 patients. Radiology 215 211-220... 

If there is a systematic (i.e., highly ordered) tissue substructure such as in white matter, diffusion is usually more restricted in one than in another direction, i.e., the molecular mobility of water is not the same in all directions. In white matter, diffusion is less restricted parallel to than perpendicular to fiber tracts. If diffusion is different along various directions, then it is termed anisotropic diffusion. In stroke imaging the avoidance of the confounding effects of anisotropy is a common goal. However,... 

Diffusion tensor imaging (DTI) is a MRI method that allows examination of white matter integrity by measuring the directional diffusion of water. When there are no structural boundaries, water diffuses in all directions equally. When there are structural barriers, including myelin and cell membranes, diffusion tends... 

Cerebral ischemia causes not only reversible and then irreversible loss of brain function, but also cerebral edema (Symon et al. 1979 Hossman 1983). Ischemic edema is partly cytotoxic and partly vasogenic. Cytotoxic edema starts early, within minutes of stroke onset, and affects the gray more than the white matter, where damaged cell membranes allow intracellular water to accumulate. Vasogenic edema, which starts rather later, within hours of stroke onset, affects the white matter more, where the damaged blood-brain barrier allows plasma constituents to enter the extracellular space. Ischemic cerebral edema reaches its maximum in two to four days and then subsides over a week or two. 

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