title: Circulating cell-free DNA levels in plasma increase with severity in experimental acute pulmonary thromboembolism.
abstract: BACKGROUND
  The diagnosis of acute pulmonary thromboembolism (APT) and its severity is challenging. No previous study has examined whether there is a linear relation between plasma DNA concentrations and the severity of APT. We examined this hypothesis in anesthetized dogs. We also examined the changes in plasma DNA concentrations in microspheres lung embolization and whether the therapy of APT with nitrite could modify APT-induced changes in plasma DNA concentrations. In vitro DNA release from blood clots was also studied.
  
  
  METHODS
  APT was induced with autologous blood clots (saline, 1, 3, or 5 ml/kg) injected into the right atrium. A group of dogs received 300 microm microspheres into the inferior vena cava to produce similar pulmonary hypertension. Another group of dogs received 6.75 micromol/kg nitrite after APT with blood clots of 5 ml/kg. Hemodynamic evaluations were carried out for 120 min. DNA was extracted from plasma samples using QIAamp DNA Blood Mini Kit and quantified using Quant-iT PicoGreen dsDNA detection kit at baseline and 120 min after APT.
  
  
  RESULTS
  APT produced dose-dependent increases in plasma DNA concentrations, which correlated positively with pulmonary vascular resistance (P=0.002, r=0.897) and with mean pulmonary arterial pressure (P=0.006, r=0.856). Conversely, lung embolization with microspheres produced no significant changes in plasma DNA concentrations. While nitrite attenuated APT-induced pulmonary hypertension, it produced no changes in plasma DNA concentrations. Blood clots released dose-dependent amounts of DNA in vitro.
  
  
  CONCLUSIONS
  Cell-free DNA concentrations increase in proportion to the severity of APT, probably as a result of increasing amounts of thrombi obstructing the pulmonary vessels.
authors.affiliation: Department of Pharmacology, Faculty of Medicine of Ribeirao Preto, University of Sao Paulo, Av. Bandeirantes, 3900, 14049-900, Ribeirao Preto, SP, Brazil.
authors.forename: Juliana A
authors.initials: JA
authors.lastname: Uzuelli
authors.forename: Carlos A C
authors.initials: CA
authors.lastname: Dias-Junior
authors.forename: Tatiane C
authors.initials: TC
authors.lastname: Izidoro-Toledo
authors.forename: Raquel F
authors.initials: RF
authors.lastname: Gerlach
authors.forename: Jose E
authors.initials: JE
authors.lastname: Tanus-Santos
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002474:Cell-Free System; D004247:DNA / Q000097:blood*; D004285:Dogs; D005260:Female; D008297:Male; D009573:Nitrites / Q000494:pharmacology / Q000627:therapeutic use; D011651:Pulmonary Artery / Q000187:drug effects / Q000503:physiopathology; D011655:Pulmonary Embolism / Q000097:blood* / Q000188:drug therapy / Q000473:pathology* / Q000503:physiopathology; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D009573:Nitrites; D004247:DNA