Pathophysiology of pulmonary arterial hypertension.

The mechanisms leading to elevations in precapillary pulmonary vascular resistance are complex and likely involve multiple pathways, but the histopathologic sequelae of these processes are restricted to a few findings, primarily neoangiogenesis, intimal and smooth muscle proliferation, vasoconstriction, and/or in situ thrombosis. Regardless of the etiology of pulmonary hypertension, abnormalities in endothelial function are often observed and likely play a central role in mediating structural changes.

Treatment of Levodopa-induced Dyskinesia.

Levodopa provides the most effective symptomatic treatment for Parkinson's disease (PD). Initiation of treatment of PD too early and/or very aggressive treatment with large doses of levodopa results in severe motor fluctuations and dyskinesias in 30% of patients with PD. Chronic levodopa treatment over a period of 9 years or more will invariably result in disabling motor fluctuations in 90% of PD patients.

The 5 Ps of acute ischemic stroke treatment: parenchyma, pipes, perfusion, penumbra, and prevention of complications.

Stroke is a treatable disease. Despite the therapeutic nihilism of the past, the advent of thrombolysis has changed the way stroke is approached. Acute ischemic stroke is a challenging and heterogeneous disease.

Screening for intracranial stenosis with transcranial Doppler: the accuracy of mean flow velocity thresholds.

Background: Patients with 50% intracranial arterial stenosis may require more intensive therapies for stroke prevention. Transcranial Doppler (TCD) is a convenient noninvasive screen for intracranial stenosis. The accuracy of different mean flow velocity (MFV) thresholds for determining the degree of stenosis remains uncertain.