title: Diurnal variation of soluble CD40 ligand in patients with acute coronary syndrome. Soluble CD40 ligand and diurnal variation.
abstract: BACKGROUND
  We sought to investigate whether day-night variations occur in the concentration of circulating soluble CD40 ligand in patients with acute coronary syndrome, as this may have practical implications.
  
  
  METHODS
  We assessed 70 consecutive ST-segment elevation myocardial infarction patients admitted into the Coronary Care Unit and 50 control subjects. Each subject was studied under strictly controlled light/dark conditions. Blood samples were drawn at 09:00 h (light phase) and 02:00 h (dark phase). Nocturnal blood samples were drawn by a trained nurse, with the help of a minute torch with a dim red light in order to avoid any direct lighting on the patient during sleep. The soluble CD40 ligand was measured using a commercially available ELISA.
  
  
  RESULTS
  Soluble CD40 ligand levels showed no diurnal variations in control subjects. In the ST-segment elevation myocardial infarction group, however, soluble CD40 ligand concentration (pg/mL) in the light phase was significantly higher than that in the dark phase (167.3+/-63.2 vs 118.9+/-48.3 pg/mL, p<0.001).
  
  
  CONCLUSIONS
  The study shows for the first time the existence of diurnal variations in soluble CD40 ligand levels in ST-segment elevation myocardial infarction patients, which indicates the need for standardizing the time of blood sampling for the assessment of this molecule, at least in studies involving ST-segment elevation myocardial infarction patients.
authors.affiliation: Department of Cardiology (Coronary Care Unit), University Hospital of Canarias, Tenerife, Spain. adrvdg@hotmail.com
authors.forename: Alberto
authors.initials: A
authors.lastname: Dominguez-Rodriguez
authors.forename: Pedro
authors.initials: P
authors.lastname: Abreu-Gonzalez
authors.forename: Martín J
authors.initials: MJ
authors.lastname: Garcia-Gonzalez
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Kaski
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood* / Q000175:diagnosis; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D023201:CD40 Ligand / Q000097:blood*; D002940:Circadian Rhythm; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D015415:Biomarkers; D023201:CD40 Ligand