Alzheimer plaque density and duration of dementia.

Thirty-two post-mortem Alzheimer cases with known duration of dementia were studied. Senile plaques (SP) in the neocortex and entorhinal cortex adjacent to the right hippocampus were stained with an antiserum to A4-beta-protein, which is specific for the amyloid protein and detects all plaque types including the amyloid-sparse diffuse plaques. The total number of SP per mm(2) of neocortex was significantly correlated to the duration of dementia (P<0.01). The total of beta-A4 stained tissue per mm(2) neocortex was also correlated to the duration of dementia (P<0.05). Our results support the assumption that more and more plaques form during the course of Alzheimer's disease and that they either disappear more slowly than they are generated or that they persist once they are formed.

Intravenous magnesium sulfate inhibits catecholamine release associated with tracheal intubation.

The effects of pre-treatment with 60 mg/kg body weight magnesium sulfate intravenous on cardiovascular responses and catecholamine release associated with tracheal intubation were measured in 15 normal patients and in 15 saline solution pre-treated controls. Magnesium pre-treatment increased heart rate by 13 +/- 3.9 beats/minute. After intubation, heart rate was unchanged in the magnesium group at 107.3 +/- 3.6 beats/minute but increased in the control group to 120.9 +/- 4.6 beats/minute (P less than 0.05). Systolic blood pressure increased after intubation from 106.8 +/- 3.1 to 121.0 +/- 4.4 mm Hg in patients given magnesium and from 106.4 +/- 3.12 to 145.1 +/- 5.6 mm Hg in the control group (P less than 0.05). Norepinephrine levels increased from 297.3 +/- 20.9 pg/ml to a peak of 532.5 +/- 30.1 pg/ml 2 minutes after intubation in the magnesium group. In controls, norepinephrine levels increased from 273.3 +/- 39.1 mg/ml to 944.6 +/- 68.7 pg/ml (P less than 0.05 for differences between groups). Epinephrine levels were unchanged from baseline after magnesium but in controls increased from 113.9 +/- 19.5 to 279.6 +/- 92.3 pg/ml (P less than 0.05). We conclude that magnesium sulfate attenuates the catecholamine mediated responses after tracheal intubation.