title: In vivo detection of hyperoxia-induced pulmonary endothelial cell death using (99m)Tc-duramycin.
abstract: BACKGROUND
  (99m)Tc-duramycin, DU, is a SPECT biomarker of tissue injury identifying cell death. The objective of this study is to investigate the potential of DU imaging to quantify capillary endothelial cell death in rat lung injury resulting from hyperoxia exposure as a model of acute lung injury.
  
  
  METHODS
  Rats were exposed to room air (normoxic) or >98% O2 for 48 or 60 hours. DU was injected i.v. in anesthetized rats, scintigraphy images were acquired at steady-state, and lung DU uptake was quantified from the images. Post-mortem, the lungs were removed for histological studies. Sequential lung sections were immunostained for caspase activation and endothelial and epithelial cells.
  
  
  RESULTS
  Lung DU uptake increased significantly (p<0.001) by 39% and 146% in 48-hr and 60-hr exposed rats, respectively, compared to normoxic rats. There was strong correlation (r(2)=0.82, p=0.005) between lung DU uptake and the number of cleaved caspase 3 (CC3) positive cells, and endothelial cells accounted for more than 50% of CC3 positive cells in the hyperoxic lungs. Histology revealed preserved lung morphology through 48 hours. By 60 hours there was evidence of edema, and modest neutrophilic infiltrate.
  
  
  CONCLUSIONS
  Rat lung DU uptake in vivo increased after just 48 hours of >98% O2 exposure, prior to the onset of any substantial evidence of lung injury. These results suggest that apoptotic endothelial cells are the primary contributors to the enhanced DU lung uptake, and support the utility of DU imaging for detecting early endothelial cell death in vivo.
authors.affiliation: Department of Biomedical Engineering, Marquette University; Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin.
authors.forename: Said H
authors.initials: SH
authors.lastname: Audi
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin; Zablocki V.A. Medical Center.
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Jacobs
authors.affiliation: Division of Cardiology, Feinberg School of Medicine, Northwestern University.
authors.forename: Ming
authors.initials: M
authors.lastname: Zhao
authors.affiliation: Zablocki V.A. Medical Center; Department of Anesthesiology, Medical College of Wisconsin; Department of Pharmacology/Toxicology, Medical College of Wisconsin.
authors.forename: David L
authors.initials: DL
authors.lastname: Roerig
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin.
authors.forename: Steven T
authors.initials: ST
authors.lastname: Haworth
authors.affiliation: Department of Biomedical Engineering, Marquette University; Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin; Department of Mathematics, Statistics, and Computer Science, Marquette University. Electronic address: anne.clough@marquette.edu.
authors.forename: Anne V
authors.initials: AV
authors.lastname: Clough
mesh_terms: D000818:Animals; D017209:Apoptosis; D001430:Bacteriocins / Q000378:metabolism; D001692:Biological Transport; D053148:Caspase 3 / Q000378:metabolism*; D015687:Cell Hypoxia; D042783:Endothelial Cells / Q000166:cytology* / Q000000981:diagnostic imaging* / Q000201:enzymology; D004789:Enzyme Activation; D008168:Lung / Q000166:cytology*; D008297:Male; D010455:Peptides / Q000378:metabolism; D011877:Radionuclide Imaging; D051381:Rats; D017207:Rats, Sprague-Dawley; D013667:Technetium
chemical_list: D001430:Bacteriocins; D010455:Peptides; C040522:duramycin; D013667:Technetium; D053148:Caspase 3
keywords: Acute lung injury; Apoptosis; Lung imaging