Alpha II-spectrin breakdown products serve as novel markers of brain injury severity in a canine model of hypothermic circulatory arrest.
BACKGROUND
The development of specific biomarkers to aid in the diagnosis and prognosis of neuronal injury is of paramount importance in cardiac surgery. Alpha II-spectrin is a structural protein abundant in neurons of the central nervous system and cleaved into signature fragments by proteases involved in necrotic and apoptotic cell death. We measured cerebrospinal fluid alpha II-spectrin breakdown products (alphaII-SBDPs) in a canine model of hypothermic circulatory arrest (HCA) and cardiopulmonary bypass.


METHODS
Canine subjects were exposed to either 1 hour of HCA (n = 8; mean lowest tympanic temperature 18.0 +/- 1.2 degrees C) or standard cardiopulmonary bypass (n = 7). Cerebrospinal fluid samples were collected before treatment and 8 and 24 hours after treatment. Using polyacrylamide gel electrophoresis and immunoblotting, SBDPs were isolated and compared between groups using computer-assisted densitometric scanning. Necrotic versus apoptotic cell death was indexed by measuring calpain and caspase-3 cleaved alphaII-SBDPs (SBDP 145+150 and SBDP 120, respectively).


RESULTS
Animals undergoing HCA demonstrated mild patterns of histologic cellular injury and clinically detectable neurologic dysfunction. Calpain-produced alphaII-SBDPs (150 kDa+145 kDa bands-necrosis) 8 hours after HCA were significantly increased (p = 0.02) as compared with levels before HCA, and remained elevated at 24 hours after HCA. In contrast, caspase-3 alphaII-SBDP (120 kDa band-apoptosis) was not significantly increased. Animals receiving cardiopulmonary bypass did not demonstrate clinical or histologic evidence of injury, with no increases in necrotic or apoptotic cellular markers.


CONCLUSIONS
We report the use of alphaII-SBDPs as markers of neurologic injury after cardiac surgery. Our analysis demonstrates that calpain- and caspase-produced alphaII-SBDPs may be an important and novel marker of neurologic injury after HCA.
Weiss
Eric S
ES
Division of Cardiac Surgery, Department of Surgery, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA.
Wang
Kevin K W
KK
Allen
Jeremiah G
JG
Blue
Mary E
ME
Nwakanma
Lois U
LU
Liu
Ming Cheng
MC
Lange
Mary S
MS
Berrong
Jennifer
J
Wilson
Mary Ann
MA
Gott
Vincent L
VL
Troncoso
Juan C
JC
Hayes
Ronald L
RL
Johnston
Michael V
MV
Baumgartner
William A
WA
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001479:Basal Ganglia / Q000473:pathology; D015415:Biomarkers / Q000134:cerebrospinal fluid*; D001930:Brain Injuries / Q000134:cerebrospinal fluid* / Q000378:metabolism / Q000473:pathology; D002154:Calpain / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D002531:Cerebellum / Q000473:pathology; D018891:Dentate Gyrus / Q000473:pathology; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D006324:Heart Arrest, Induced / Q000009:adverse effects*; D007036:Hypothermia, Induced; D015151:Immunoblotting; D008297:Male; D023421:Models, Animal; D009336:Necrosis / Q000134:cerebrospinal fluid; D010296:Parietal Lobe / Q000473:pathology; D013049:Spectrin / Q000134:cerebrospinal fluid*
D015415:Biomarkers; D013049:Spectrin; D002154:Calpain; D020169:Caspases