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.

Cerebrospinal fluid ferritin in brain necrosis: evidence for local synthesis.

Ferritin was measured in cerebrospinal fluid (CSF) and serum of an unselected neurological population. An increase in CSF ferritin was found to be associated with pathological processes in which there was either necrosis or haemorrhage involving the brain. There was no correlation between the CSF and serum concentrations of ferritin in the reference population. Neither was there any correlation between CSF ferritin and CSF albumin in the reference population. After subarachnoid haemorrhage, intrathecal production of ferritin was found to occur since in some patients the concentration of ferritin in CSF was higher than that of homologous serum. Even in the reference population the concentration of ferritin found in the CSF was much higher than could be explained by passive transfer across the blood-CSF barrier. Therefore local synthesis of ferritin by brain cells occurs even under normal circumstances.

Magnesium and inorganic phosphate content in CSF related to blood-brain barrier function in neurological disease.

In normal controls and in a large number of neurological patients divided into certain disease groups both Mg and PO4 were determined in cerebrospinal fluid (CSF) and serum. For both Mg and PO4 there was a marked concentration gradient between CSF and serum in normals where Mg was higher and PO4 content lower in CSF. Comparison of CSF values with serum values of patients showed pathological changes only in CSF, serum values always being within the control range. A number of disease processes associated with a disturbance of blood-brain barrier (BBB) function such as inflammatory CNS disease or CNS tumors showed significant alterations of PO4 concentrations in CSF which are interpreted as an approximation of serum values. A similar decrease of Mg did not reach statistical significance. Both Mg and PO4 in CSF showed a correlation with CSF protein concentrations, but no relationship with cells in CSF. Patients with cerebrosvascular disease were not significantly different from controls as regards their Mg and PO4 in CSF, but a small subgroup consisting of patients with an intracranial hemorrhage showed elevation of both Mg and PO4 which could signify cell necrosis rather than BBB dysfunction. Patients with disc protrusion or peripheral neuropathy did not demonstrate any abnormality of CSF Mg and PO4. In the multiple sclerosis group individual patients had elevated CSF concentrations of PO4 but the group as a whole is not different from the controls.