Damaged brain tissue

Mannitol is an agent that may be used in patients with I impending cerebral herniation. Mannitol is an osmotic diuretic that shifts brain osmolarity from the brain to the blood. Doses of 100 g (1-2 g/kg) as an intravenous bolus should be used. Repeated doses typically are not recommended because mannitol may diffuse into damaged brain tissue, leading to rebound increased ICP.21... 

A resonance unique to brain and nerve tissue and believed to be a specific marker for neurons (nerve cells) is V-acetylaspar-tate (NAA), structure 16-6, appearing at 2.0 ppm. NAA often decreases in the damaged brain tissue, suggesting that neurons have died. The damaged brain tissue also contains elevated lactate, structure 16-7, which is an indication that anaerobic metabolism, a pathway forced by oxygen deficit, is taking place. Only the methyl doublet of lactate (1.3 ppm) appears in the spectrum the methine quartet overlaps the water resonance and is normally never observed in vivo. 

With modest impairment of blood flow, this mechanism allows for preservation of oxidative metabolism without alteration in electrical function. However, when CPP and therefore CBF are sufficiently low, OEF reaches a maximum and cannot increase further. Brain tissue ceases to function electrically, resulting in a neurologic deficit. Microvascular collapse occurs, and CBV falls. If the oxygen supply falls low enough, the tissue dies. Of critical clinical importance is the observation that the amount of time it takes for tissue to suffer irreversible damage is inversely related to the severity of the ischemic insult. Tissue that is completely deprived of blood will die within a few minutes, but less severely hypoperfused tissue may survive for many hours, and may be saved by timely thrombolysis that restores perfusion, or perhaps by another therapeutic intervention. 

These agents rapidly permeate through the skin. Extensive skin contamination can damage susceptible tissue including blood cells and the liver. Casualties may develop signs of systemic arsenic toxicity including diarrhea, damage to the liver, kidneys, nervous system, red blood cells, and the brain. 

Some deaths. Yellow discoloration of sclera of eye passing of red-colored urine. Copper concentrations, in mg/kg DW, from sheep fed nonheliotrope diets were 1394 in liver (824 in controls) and 132 in kidney (20 in controls). Sheep on heliotrope diet had 2783 mg/kg DW in liver and 321 mg Cu/kg DW in kidney Severe morphological changes in liver, kidney, and brain tissue damage continued after cessation of copper and was sufficiently severe to lead to repeated hemolytic crises. Maximum copper concentrations at day 83 were 3289 mg/kg DW in liver (138 in controls), and 683 in kidney (15 in controls)... 

Backhauss C, Kriegistein J. (1992). Extract of kava (Piper methysticum) and its methysticin constituents protect brain tissue against ischemic damage in rodents. Eur J Pharmacol. 215(2-3) 265-69. 

Two in vivo microdialysis techniques are employed in the clinical setting open and closed, which refer to the degree of exposure of the brain (Kanthan and Shuaib, 1995). In the open technique, a craniotomy is performed to expose the brain and the microdialysis probe is then implanted into the brain region of interest. In the closed technique, a burr hole is made in the skull and a modified probe is then inserted into the brain via the burr hole. The closed technique permits multiple insertions of the dialysis probe into the brain tissue and consequently minimizes problems associated with prolonged probe placement, such as edema and gliosis (Kochs, 1997). Therefore, the closed technique allows for continuous but intermittent sampling and has lower risks of tissue damage and infection than the open method (Kanthan and Shuaib, 1995). 

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