To define the temporal characteristics of cocaine-induced coronary vasoconstriction in humans and to assess the relation between cocaine-induced coronary vasoconstriction and the blood concentration of cocaine and its main metabolites.

To determine if the semirecumbent position (45-degree angle) decreases aspiration of gastric contents to the airways in intubated and mechanically ventilated patients.

To assess the effect of a program of supervised fitness walking and patient education on functional status, pain, and use of medication in patients with osteoarthritis of the knee.

To determine the efficacy of acetazolamide in the treatment of patients with acute mountain sickness and the effect of the drug on pulmonary gas exchange in acute mountain sickness.

To determine if deterioration in renal function could be ameliorated by adding cyclophosphamide to corticosteroid therapy in patients with progressive membranous glomerulopathy.

To assess whether daily ingestion of yogurt containing Lactobacillus acidophilus prevents vulvovaginal candidal infections.

To determine whether clonidine can slow ventricular rate in patients with rapid atrial fibrillation.

To investigate in the prospective Helsinki Heart Study, whether chronic Chlamydia pneumoniae infection, indicated by elevated antibody titers against the pathogen, chlamydial lipopolysaccharide-containing immune complexes, or both, is a risk factor for coronary heart disease.

To determine the clinical and economic effects of granulocyte macrophage colony-stimulating factor (GM-CSF) as adjunct therapy in relapsed or refractory Hodgkin disease.

To determine the hemopoietic effects of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients having autologous hemopoietic stem cell transplantation for Hodgkin or non-Hodgkin lymphoma.

To describe the clinical course of severe lupus nephritis and to identify the risk factors for progression to renal failure among patients treated with prednisone and short-term courses of low-dose oral cyclophosphamide.

To identify echocardiographic predictors of arterial thromboembolism in patients with nonrheumatic atrial fibrillation and to determine whether these add to clinical variables for risk stratification.

To compare pyrimethamine plus clindamycin (PC) to pyrimethamine plus sulfadiazine (PS) as a treatment for toxoplasmic encephalitis (TE) in patients with the acquired immunodeficiency syndrome (AIDS).

To identify those patients with nonrheumatic atrial fibrillation who are at high risk and those at low risk for arterial thromboembolism.

To evaluate the safety and immunologic and antiviral effects of combination therapy with zidovudine and dideoxycytidine (ddC) in patients with advanced human immunodeficiency virus type 1 (HIV) infection.

To determine the efficacy of glucose tolerance factor (GTF)-chromium for increasing serum levels of high-density lipoprotein (HDL) cholesterol in patients taking beta-blockers.

To determine the effects of tamoxifen on risk factors for cardiovascular disease in disease-free postmenopausal women.

To compare the efficacy, toxicity, and cost-effectiveness of double beta-lactam therapy with monotherapy.

To determine whether an increase in dietary potassium intake from natural foods reduces the need for antihypertensive medication in patients with essential hypertension.

Seven randomized studies during the past 5 years have evaluated or are evaluating the efficacy of warfarin or aspirin or both in decreasing the risk of embolic events in patients with nonrheumatic atrial fibrillation. By March 1990, two of the studies had been published, both of which showed a statistically significant decrease in embolic events in patients treated with warfarin and a low rate of major bleeding events. The investigators associated with the other ongoing studies were forced to consider how these results should affect the decision to recruit and continue follow-up of patients in their own studies. The Steering Committee of the Canadian Atrial Fibrillation Anticoagulation (CAFA) study thought the newly published results from other studies were valid, clinically important, and generalizable. The committee considered the following options for the CAFA study: continue patient recruitment as planned, provide the data available in CAFA to its External Safety and Efficacy Monitoring Committee for analysis to determine whether the CAFA data already showed a benefit of warfarin, stop patient recruitment but continue to follow patients in the group to which they were assigned, stop the trial immediately and perform a final analysis, and attempt to perform a meta-analysis of all data available from all trials. The Steering Committee of CAFA decided that the evidence of benefit with warfarin, from the two published studies, was sufficiently compelling as to stop recruitment into CAFA without any preliminary examination of the CAFA data.