We studied the binding of the calcium antagonist neurotoxin [125I]-omega conotoxin (GVIA) in age-matched human brains from normal, Alzheimer's disease and non-Alzheimer's dementia patients. Crude preparations of plasmalemmal membranes from frontal cortex were utilized. Saturation isotherms were subjected to Scatchard analysis to determine maximal binding capacity (Bmax) and binding affinity (Kd). In all brain samples tested, [125I]-GVIA binding was homogenous to a single class of high affinity binding sites. Scatchard analysis of saturation isotherms gave the following estimates for normal brains (mean +/- S.D., n = 7): Bmax = .630 +/- .200 pmol/mg and Kd = .177 +/- .054 nM. No significant change was observed in the Kd or Bmax estimates for [125I]-omega conotoxin binding in Alzheimer's disease or non-Alzheimer's dementia brains when compared to normal brains. Although these findings do not rule out the existence of localized changes in calcium channel receptor binding in the frontal cortex of Alzheimer's disease patients, the results do suggest that the neuronal voltage sensitive calcium channel may be unaltered in Alzheimer's disease.

Aged↗

PubMedDate not supplied

Effect of chronic smoking on fibrinolysis.

The aim of the study was to investigate the long-term chronic effects of smoking on the fibrinolytic enzyme system by comparing two groups of healthy male volunteers (aged 30 to 40 years). One group consisted of 15 habitual smokers who consumed 20 or more cigarettes a day; the other consisted of 15 nonsmokers. Fibrinolysis was studied at rest (baseline) and after infusion of 1-desamino-8-D-arginine vasopressin (DDAVP; 0.4 micrograms/kg body weight). Smokers had significantly lower baseline blood fibrinolytic activity as determined by the overall assays: dilute blood clot lysis (p less than or equal to 0.05) and euglobulin-fibrin plate assay (p less than or equal to 0.05). Further analysis showed that these low activities could be attributed to a lower baseline level of extrinsic tissue-type plasminogen activator (t-PA) activity (p less than or equal to 0.05) in the smokers. There were no significant differences between the groups in various fibrinolytic inhibitors or in the intrinsic fibrinolytic activation pathways. The increased levels of t-PA activity and factor VIII R:Ag in response to DDAVP were also reduced in the smokers (p less than or equal to 0.01). The relative increase (ratio of post-DDAVP activity/baseline activity) for these parameters was not significantly different for the two groups. Smokers also had significantly higher levels of the acute phase reactants, alpha 1-antitrypsin (p less than or equal to 0.02) and plasminogen (p less than or equal to 0.02) and C-reactive protein (p less than or equal to 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Ocular manifestations of the Marfan syndrome.

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Adolescent↗