Page 71 - NNS 2014 Program & Abstract Book

A4-07
DETERMINING THE FEASIBILITY OF USING HEART-
RATE VARIABILITY FOR THE IDENTIFICATION OF MILD
TBI IN ASYMPTOMATIC PARTICIPANTS
Bashirelahi, K.B.1,2, Nathan, D.E.1,2, Goekler, J.R.1, Keyser, D.O.1,
Rapp, P.E.1
1Uniformed Services University, Bethesda, US
2Henry Jackson Foundation, Bethesda, US
Many who experience a mild traumatic brain injury (mTBI) have
transient symptoms. However, a subset of the mTBI population will
present symptoms weeks, months, or years after the event has occurred.
As a result, health-care providers and even the injured person may not
identify the mTBI incident as being the cause of their current symptoms.
Therefore, it is crucial that an accurate method of assessing mTBI in the
asymptomatic individual be developed. If left untreated, individuals with
chronic mTBI sub-threshold deficiencies may be at higher risk of de-
veloping serious neurological and psychiatric disorders. Heart-rate var-
iability (HRV), the variation in time intervals between heartbeats,
reflects the sympathetic and parasympathetic balance of the autonomic
nervous system. We hypothesized that HRV measures can be used to
identify the population of asymptomatic mTBI individuals from a
healthy control population months following the TBI incident. In this
study, five mTBI participants and 14 controls participated in an IRB
approved research protocol consisting of two sessions, each six months
apart. Subjects were presented with a battery of cognitive tasks. Elec-
trocardiogram (ECG) data was acquired and processed to obtain mea-
sures of heart rate and HRV. A diagnostic, self-report assessment for
depression, the PHQ-9, was administered as part of our behavioral as-
sessments. The PHQ-9 showed no significant difference in depression
measures between the controls and mTBI subjects. However, results for
the HRV measure suggest a clear difference with controls and mTBI
subjects between sessions as determined by repeated measures ANOVA
(F= 6.872, p = 0.022). These results suggest that HRV is an objective
measure of mTBI impairment during task performance even in the
asymptomatic mTBI victim. Identification of such individuals via HRV
assessment may be a useful tool in longitudinal tracking of mTBI re-
covery and response to interventions targeted at restoration of autonomic
function. This research is on-going and updated results will be presented.
Key words
electrocardiogram, heart rate variability, traumatic brain injury
A4-08
IMMUNO-CHAIN REACTION: A NOVEL ULTRASENSITIVE
ASSAY FOR RAPID TRIAGING OF BRAIN INJURY
Zhu, L., Ledden, B., Kumar, S.
SFC Fluidics, Fayetteville, USA
Rapid, real-time triaging of mild traumatic brain injury (mTBI) or
concussion with a simple pinprick blood test at the sideline or at the
point of injury necessitates measuring protein biomarker candidates at
fM concentrations. The inherent characteristics of many immunoassay
methods preclude the development of a viable blood test based on them.
To overcome this hurdle, we report here a novel immunoassay tech-
nology based on Immuno-Chain Reaction (ICR), which successfully
demonstrated the assay of glial fibrillary acidic protein (GFAP), a
leading biomarker of gliosis in the acute phase of TBI, in the 0-100 pg/
mL range in five minutes using less than 3 ll human mTBI serum.
Duplex detection of GFAP and bovine IgG spiked in human serum has
also been demonstrated. Results indicate that, using spiked bovine IgG
as an internal standard, it is possible to triage mTBI/concussion based on
a specific cutoff. Day-to-day reproducibility was demonstrated for the
detection of 10 pg/mL GFAP in serum. The feasibility of ICR assay in
banked CSF samples and detection of autoantibodies have also been
verified. ICR achieves an ultralow limit of detection through amplifi-
cation brought about by a PCR-like, immuno-displacement chain reac-
tion. Because all the reagents are pre-immobilized, ICR-based devices
do not require any reagent storage, pumps or valves or an associated
control system. This greatly simplified instrumentation requires only a
control board for signal readout and makes the device affordable, reliable
and user-friendly. The ICR assay is inherently ideal for rapid detection of
protein biomarkers in ultralow concentrations and has great potential for
triaging concussion and other emergency or low resource indications.
Key words
biomarker, glial fibrillary acidic protein, immunoassay, mild traumatic
brain injury, triage
A4-09
HUMAN ASTROGLIAL MARKERS ARE DEFINED BY RE-
LEASE MECHANISMS AND ARE ELEVATED IN TBI PA-
TIENTS’ CSF AND SERUM
Wanner, I.B.1, Shen, S.2, Halford, J.1, Sanville, D.1, Dietrich, W.D.3,
Glenn, T.C.4 , Sofroniew, M.V.5 , Loo, J.A.2, Levine, J.N.1
1UCLA, Semel Institute, Los Angeles, USA
2UCLA, Dept. of Chemistry & Biochemistry, Los Angeles, USA
3Univ. of Miami, Miami Project to Cure Paralysis, Miami, USA
4UCLA, Dept Neurosurgery, Brain Injury Research Center, Los An-
geles, USA
5UCLA, Dept. of Neurobiology, Los Angeles, USA
There is an unmet need for chemical surrogate markers of traumatic
brain injury (TBI). Cellular consequences of mechanical trauma are
poorly understood. The goals of this study were to define the release
parameters of a new set of astroglial enriched proteins in a controlled
in vitro injury model and measure their elevation in TBI patient’s CSF
and serum. Densitometric immunoblotting analyses and quantitative
mass spectrometry measurements using multiple reaction monitoring
(MRM) of the fluid samples were established. Percent human astrocytes
with membrane permeability and cell death were quantitated using dye
uptake imaging. Marker release levels were related to trauma severity
and analyzed over time postinjury. Abrupt pressure stretching caused
acute membrane permeability (30 min postinjury) whereas severity-
dependent cell death was seen by 48 hours postinjury. Astrocyte-en-
riched markers were released acutely and increased with severity and
over time postinjury. TBI patients’ CSF levels of these astroglial
markers were elevated compared to controls with highest amounts on
injury day and secondary peaks over time postinjury. Correlation ana-
lyses showed covariant release pattern among these astroglial proteins.
Selected astroglia markers were detected in TBI patients’ serum indi-
cating blood brain barrier passage. Thus, our controlled in vitro model
defined human astrocyte’s trauma responses and release kinetics for a
new set of astroglial proteins that we validated in TBI patient’s CSF and
serum. Release from mechanoporated cells prior to significant cell death
distinguished these proteins from cell death inflicted trauma markers. In
conclusion, we provide a panel of human astrocyte-derived biomarker
candidates useful for acute diagnosis and monitoring the progressive
pathophysiology of TBI patients with varying severities.
Key words
CSF, in vitro model, proteomics, serum
A-39