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Product innovation

GRACE Laboratories believes these diagnostic tools will become the standard of care in the diagnosis and detection of consequences of mTBI. GRACE Labs has developed two biomarkers, AMPA receptor peptide (AMPAR peptide) and GluR1 antibodies, available for detection on different technological platforms that may be used in various medical settings.

Central nervous system biomarkers generally represent proteins that are specifically produced in the brain and spinal cord and are relatively sequestered in the CNS, due mainly to the presence of an intact blood-brain barrier. When the blood-brain barrier is compromised due to brain injury or disorders, brain peptides/proteins can be released in the circulation and accumulate in the blood. The detection and quantification of CNS-specific proteins released into the blood as the result of brain injury, therefore, provides a potentially attractive means of diagnosing injuries using minimally invasive procedures.

When TBI occurs, a cascade of biochemical events is initiated. Mild TBI affects electrical and chemical circuits, subsequently leading to a failure in blood circulation. AMPA receptors are key metabolites controlling these processes. The ionotropic glutamate receptor (AMPA receptor) regulates electric signals in neuronal cells and first reacts in the event of dendrites impairment due to local microvessel dysfunctions. Compression and microvessel damage after mild TBI lead to edema-activating necrosis. Excessive glutamate amounts activate AMPA receptors and trigger abundant influx of calcium leading to overexpression of glutamate receptors in extra-synaptic areas. The degradation of receptors by thrombin-activated serine proteases results in peptide fragments entering the blood stream through the compromised blood-brain barrier (BBB) where they may be detected. N-terminal domain of GluR1 (component of AMPAR) is the most sensitive to the cleavage.

AMPAR peptide is proposed as a novel biomarker of necrotic event following concussion and mild TBI. Peptide levels can be detected in the blood stream immediately after mild brain injury and reflect the severity of brain damage. The AMPAR peptide concentrations in plasma of normal adults is less than 0.5 ng/mL. Increased concentrations of this peptide above 2 ng/mL indicate the presence of tissue-based evidences of concussion and mild TBI. Cleaved peptides appear in the blood stream as “foreign antigens”, which lead to immune response. Antibodies to GluR1 generated by immune system have been clinically shown to be marker for adverse consequences of mTBI including brain-related seizures and epilepsy.

GRACE Peptide Test

     The GRACE Peptide test is a Magnetic Particle-based enzyme-linked immunosorbent assay (MP-ELISA) intended for the quantitative determination of N-terminal peptide fragment of AMPA receptors in plasma. The test is intended to be used in conjunction with clinical evaluation and radiological methods for diagnosis of concussions and mild traumatic brain injury (TBI).



     Concentrations of AMPAR peptide are determined immunochemically in a blood assay. The affinity purified specific antibodies of AMPA receptor subunit are immobilized on magnetic particles. Immobilized AMPAR antibodies react with the sample containing AMPAR peptides and HRP-conjugated affinity purified specific antibodies against AMPAR peptide.

     The immunocomplex that is formed for 30 minutes and quantitatively determined using HRP-TMB detection reaction. An acidic stopping solution is then added. The color converts from blue to yellow. The intensity of the color is directly proportional to the concentration of AMPAR peptide in the sample. A dose response curve of the absorbance measured at 450 nm or using dual wave measurement at 450 nm and 630 nm vs. concentration is generated. AMPAR peptide concentrations in the plasma samples are determined directly from this calibration curve. Identifies the time course of AMPAR peptide concentrations associated with an stage of concussion

  • a. Diagnosis of mTBI
  • b. Differentiation between mTBI vs. other conditions
  • c. Ruling out mimics

GRACE Antibody Test

     The GRACE- Antibodies Test is a serological enzyme-linked immunosorbent assay (ELISA) for the quantitative determination of antibodies to the GluR1 subunit of human AMPA glutamate receptor in serum. The test is intended to be used in conjunction with clinical evaluation for determining the consequences of concussion.



     Concentrations of GluR1 antibodies are determined immunochemically in a serological assay. GluR1 synthetic peptide, the fragment of AMPA receptors, is coated on the solid phase of a microtiter plate (MTP). In a first incubation step, antibodies in the sample react with the solid phase bound GluR1 peptide. After intensive washing, the antibodies captured on the MTP react with horseradish peroxidase labeled Protein A (Protein A-HRP).

     The immunocomplex is formed and quantitatively determined in a third incubation step via HRP/TMB-detection reaction. An acidic stopping solution is then added. The color converts from blue to yellow. The intensity of the yellow color is directly proportional to the concentration of GluR1 antibodies in the sample. A dose response curve of the absorbance measured at 450 nm or using dual wave measurement at 450 nm and 630 nm vs concentration is generated. GluR1 antibody concentrations in the diluted serum samples are determined directly from this calibration curve.

     GRACE Antibody test characterizes the time course of GluR1 antibody concentrations associated with prior mTBI and correlates these values with adverse consequences of mTBI.

     GRACE Antibody and GRACE Peptide assays are complementary tests that are acceptably precise, linear, accurate, and not subject to appreciable cross-reactivity or interference. The minimum detection limits of 0.1 ng/mL for the GRACE Peptide test and 0.5 ng/mL for the GRACE Antibody test are acceptable for their intended use. The tests are reproducible across several reagent lots and multiple operators and provide reliable and reproducible results when used by professional clinical laboratories. Performance figures for the GluR1 assay are 90% sensitivity and 97% specificity. The test proved to be conclusive in a population prevalence study linked with an in-hospital study.

     Each test kit comprises a box containing 12 rows of small wells in which a patient’s blood is treated with several chemicals; as well as some ―off-the-shelf‖ and two proprietary reagents.