Quantification of Axonal Damage in Traumatic Brain Injury
: Diffuse axonal injury is a primary feature of head trauma and is one of the most frequent causes of mortality and morbidity. Diffuse axonal injury is microscopic in nature and difficult or impossible to detect with imaging techniques. The objective of the present study was to determine whether axo...
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Published in | Journal of neurochemistry Vol. 72; no. 2; pp. 741 - 750 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Oxford UK
Blackwell Science Ltd
01.02.1999
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Subjects | |
Online Access | Get full text |
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Summary: | : Diffuse axonal injury is a primary feature of head trauma
and is one of the most frequent causes of mortality and morbidity. Diffuse
axonal injury is microscopic in nature and difficult or impossible to detect
with imaging techniques. The objective of the present study was to determine
whether axonal injury in head trauma patients could be quantified by measuring
levels of CSF tau proteins. Tau proteins are structural microtubule binding
proteins primarily localized in the axonal compartment of neurons. Monoclonal
antibodies recognizing the form of tau found in the CSF of head trauma
patients were developed by differential CSF hybridoma screening using CSF from
head trauma and control patients. Clones positive for head trauma CSF tau
proteins were used to characterize this form of tau and for ELISA development.
Using the developed ELISA, CSF tau levels were elevated >1,000‐fold in head
trauma patients (mean, 1,519 ng/ml of CSF) when compared with patients with
multiple sclerosis (mean, 0.014 ng/ml of CSF ; p < 0.001), normal
pressure hydrocephalus (nondetectable CSF tau), neurologic controls (mean,
0.031 ng/ml of CSF ; p < 0.001), or nonneurologic controls
(nondetectable CSF tau ; p < 0.001). In head trauma, a relationship between clinical improvement and decreased CSF tau levels was observed. These data suggest that CSF tau levels may prove a clinically useful assay for quantifying the axonal injury associated with head trauma and monitoring efficacy of neuroprotective agents. Affinity purification of CSF tau from head trauma patients indicated a uniform cleavage of ~ 18 kDa from all six tau isoforms, reducing their apparent molecular sizes to 30‐50 kDa. These cleaved forms of CSF tau consisted of the interior portion of the tau sequence, including the microtubule binding domain, as judged by cyanogen bromide digestion. Consistent with these data, CSF cleaved tau bound taxolpolymerized microtubules, indicating a functionally intact microtubule binding domain. Furthermore, epitope mapping studies suggested that CSF cleaved tau proteins consist of the interior portion of the tau sequence with cleavage at both N and C terminals. |
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Bibliography: | BAP, bacterial alkaline phosphatase ; CNBr, cyanogen bromide ; CT, computed tomography ; cTau, cleaved tau ; DAI, diffuse axonal injury ; GCS, Glasgow Coma Scale ; Mab, monoclonal antibody ; MAP, microtubule‐associated protein ; PAGE, polyacrylamide gel electrophoresis ; SDS, sodium dodecyl sulfate ; TBI, traumatic brain injury ; TBST, Tris‐buffered saline containing Tween. Abbreviations used |
ISSN: | 0022-3042 1471-4159 |
DOI: | 10.1046/j.1471-4159.1999.0720741.x |