Activation of protease-activated receptors 3 and 4 accelerates tissue factor-induced thrombin generation on the surface of vascular smooth muscle cells.

Objective: To determine factors regulating human aortic smooth muscle cells (HASMC) supported tissue factor-induced thrombin generation.

Methods And Results: The addition of nonlipidated tissue factor and Ca(2+) to HASMCs maintained in reptilase-treated platelet-poor plasma resulted in the robust formation of thrombin after a lag phase of approximately 6 minutes. Pretreatment with low concentrations of α-thrombin before the addition of tissue factor and Ca(2+) accelerated the rate of thrombin generation (time to reach half of peak thrombin was reduced by [mean ± SD] 42.

Relation of platelet count to bleeding and vascular complications in patients undergoing coronary angiography.

Vascular and bleeding complications are associated with significant morbidity and mortality, limited data are available on the relation between these complications and the platelet count in patients undergoing coronary angiography. We, therefore, performed a retrospective cohort analysis of 3,466 consecutive adults undergoing coronary angiography at a single institution during a 2-year period. The mean + or - SD age was 60 + or - 13 years; 58% of the patients were men, 67% were white, and 27% were black.

Biventricular pulsus alternans.

Pulsus alternans is a rare hemodynamic condition characterized by beat-to-beat variability in systolic pressure. It is attributed to variations in stroke volume with alternate cardiac cycles and is typically seen in patients with advanced myopathic conditions. Left ventricular pulsus alternans is rare, and right ventricular pulsus alternans is even less common.

Local distribution and toxicity of prolonged hippocampal infusion of muscimol.

Object: The activity of gamma-aminobutyric acid (GABA), the principal inhibitory neurotransmitter, is reduced in the hippocampus in patients with complex partial seizures from mesial temporal sclerosis. To provide preliminary safety and distribution data on using convection-enhanced delivery of agents to treat complex partial seizures and to test the efficacy and safety of regional selective neuronal suppression, the authors infused muscimol, a GABA-A receptor agonist, directly into the hippocampus of nonhuman primates using an integrated catheter electrode.

Methods: Ten rhesus monkeys were divided into three groups: 1) use of catheter electrode alone (four monkeys); 2) infusion of escalating concentrations of muscimol followed by vehicle (three monkeys); and 3) infusion of vehicle and subsequent muscimol mixed with muscimol tracer (three monkeys).