Svetlana A. Dambinova

Blood Test Detecting Autoantibodies to N-Methyl-d-aspartate Neuroreceptors for Evaluation of Patients with Transient Ischemic Attack and Stroke

BACKGROUND Stroke is a multisystemic disorder that includes mechanisms of thrombosis and neurotoxic coupling. Key metabolites of the molecular cascade following biochemical events appear simultaneously in brain tissue, the blood-brain barrier, and brain vessels, activating the immune system and generating autoantibodies (aAbs) to brain-specific antigens. We developed an ELISA blood test to measure aAbs to a subtype of N-methyl-D-aspartate (NMDA) receptors, which are the key markers of neurotoxicity underlying cerebral ischemia. We investigated the diagnostic accuracy of serum aAbs to NR2A/2B, a subtype of NMDA receptors, in assessing transient ischemic attack (TIA) and ischemic stroke (IS) and its ability to distinguish cerebral ischemia from intracerebral hemorrhage (ICH). METHODS Autoantibodies to NR2A/2B were measured in 360 serum samples: 105 from TIA/stroke patients and 255 from controls, including patients with controlled hypertension/atherosclerosis and gender- and age-matched healthy individuals. RESULTS Patients with TIA (n = 56) and acute IS (n = 31) had significantly higher NR2A/2B aAb concentrations than controls (P <0.0001). The test sensitivities for TIA and IS were 95% and 97%, respectively, and predictive values were 86% and 91% at a cutoff point of 2.0 micro g/L. The area under the ROC curve was 0.99. Monitoring NR2A/2B aAbs within 72 h differentiated IS and ICH (P <0.001) and was confirmed by magnetic resonance imaging and computed tomography. CONCLUSIONS NR2A/2B aAbs are independent and sensitive serologic markers capable of detecting TIA with a high posttest probability and, in conjunction with neurologic observation and neuroimaging, ruling out ICH. The test may help assess risk of TIA in routine general practice and may potentially be useful in assisting diagnosis of acute IS in the emergency setting.

Behavioral and neurochemical vulnerability during adolescence in mice: studies with nicotine.

People are very likely to start psychoactive drug use during adolescence, an earlier onset being associated with a higher risk of developing addiction later in life. In experiment I, Pre- (postnatal day (pnd) 23–35), Mid- (pnd 36–48), or Post- (pnd 49–61) adolescent mice underwent a restricted-drinking period (2 h/day for 12 days), one bottle containing water and the other containing nicotine (10 mg/l) or water. After this period, Mid-adolescents showed prominent exploration and reduced anxiety in the plus-maze. This ontogenetic profile was dampened by nicotine consumption. After 2 months, these mice were tested in a novel environment (30 min/day for 3 days). Locomotor-habituation profiles were specifically disrupted by nicotine consumption during Mid-adolescence, suggesting this age as a critical period. In experiment II, Mid-adolescent (pnd 35–44) and adult (pnd >70) mice were pretreated with nicotine (0, 0.03, 0.10, 0.30 mg/kg/day for 10 days). Acute nicotine administration had opposite effects on anxiety in adolescents and adults. At 2 months after pretreatment, we measured levels of AMPA GluR2/3 subunits, thought to be involved in the control of addictive behaviors. Nicotine exposure during Mid-adolescence dose-dependently downregulated these subunits in the striatum and hippocampus, but comparable exposure during adulthood had either opposite or no effects. NMDA NR2A/B subunits were affected by nicotine, but without age-related differences. The present data identified a nicotine-vulnerable age window, characterized by long-term disruption of locomotor habituation and downregulation of AMPA receptors. These findings support neurobiological vulnerability to drugs in adolescent humans.

NMDA Receptor Antibodies Predict Adverse Neurological Outcome After Cardiac Surgery in High-Risk Patients

Background and Purpose— The goal of this study was to compare the predictive ability of S100B, N-methyl-d-aspartate (NMDA) receptor antibodies (NR2Ab) and C-reactive protein (CRP) for neurological deficits after cardiac surgery with cardiopulmonary bypass (CPB). Methods— We investigated 557 high-risk adult patients who underwent coronary artery or valve replacement surgery using CPB as a substudy of a prospective, blinded, multicenter clinical trial. Serum concentrations of S100B (n=513 patients), NR2Ab (n=398) and CRP (n=510) were measured preoperatively, 24 and 48 hours after CPB. Neurological adverse events were assessed at baseline and postoperative days 1 and 2; neurocognitive function (mini-mental status examination) was assessed at baseline and on postoperative days 1, 7 and 28. Results— Fifty-five (9.9%) patients had moderate or severe neurological adverse events (confusion/delirium, transient ischemic attack, or stroke) within 48 hours of CPB. Women had significantly more neurological complications than men (15.5% versus 7.8%; P=0.007). Ninety-six percent (24/25) of patients with NR2Ab concentrations ≥2.0 ng/mL preoperatively had neurological complications within 48 hours post-CPB, versus only 5.4% (20/373) of patients with NR2Ab concentrations <2.0 ng/mL, resulting in a 17.9-fold increase (95% CI, 11.6 to 27.6) in postoperative neurological complications for patients with high levels of NR2A antibodies. Preoperative serum S100B and CRP did not predict neurological complications from CPB. Decreased mini-mental status examination scores for orientation, attention and recall were associated with neurological adverse events early after CPB. Conclusions— Preoperative serum concentrations of NR2Ab, but not S100B or CRP, are predictive of severe neurological adverse events after CPB. Patients with a positive NR2Ab test (≥2.0 ng/mL) preoperatively were nearly 18 times more likely to experience a postoperative neurological event than patients with a negative test (<2.0 ng/mL).

Diagnostic potential of the NMDA receptor peptide assay for acute ischemic stroke.

Background The acute assessment of patients with suspected ischemic stroke remains challenging. The use of brain biomarker assays may improve the early diagnosis of ischemic stroke. The main goal of the study was to evaluate whether the NR2 peptide, a product of the proteolytic degradation of N-methyl-D-aspartate (NMDA) receptors, can differentiate acute ischemic stroke (IS) from stroke mimics and persons with vascular risk factors/healthy controls. A possible correlation between biomarker values and lesion sizes was investigated as the secondary objective. Methods and Findings A total of 192 patients with suspected stroke who presented within 72 h of symptom onset were prospectively enrolled. The final diagnosis was determined based on clinical observations and radiological findings. Additionally gender- and age-matched healthy controls (n = 52) and persons with controlled vascular risk factors (n = 48) were recruited to compare NR2 peptide levels. Blinded plasma was assayed by rapid magnetic particles (MP) ELISA for NR2 peptide within 30 min and results for different groups compared using univariate and multivariate statistical analyses. There was a clinical diagnosis of IS in 101 of 192 (53%) and non-stroke in 91 (47%) subjects. The non-stroke group included presented with acute stroke symptoms who had no stroke (n = 71) and stroke mimics (n = 20). The highest NR2 peptide elevations where found in patients with IS that peaked at 12 h following symptom onset. When the biomarker cut off was set at 1.0 ug/L, this resulted in a sensitivity of 92% and a specificity of 96% to detect IS. A moderate correlation (rs = 0.73) between NR2 peptide values and acute ischemic cortical lesions (<200 mL) was found. Conclusions This study suggests that the NR2 peptide may be a brain specific biomarker to diagnose acute IS and may allow the differentiation of IS from stroke mimics and controls. Additional larger scale clinical validation studies are required.

AMPAR peptide values in blood of nonathletes and club sport athletes with concussions

OBJECTIVES α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) peptide, a product of the proteolytic degradation of AMPA receptors in healthy nonathletes and athletes with concussions, is assessed. The detection of AMPAR peptide in conjunction with neuropsychological testing and neuroimaging is undertaken. SUBJECTS Persons (n = 124, 19-23 years) are enrolled in the pilot-blinded study according to approved Institutional Review Board protocols at Kennesaw State University and DeKalb Medical. METHODS AMPAR peptide plasma assay was performed using magnetic particles-enzyme-linked immunosorbent assay. All participants had neurocognitive tests (ImPACT); selected subjects with concussions were followed-up with magnetic resonance imaging and neurologic consultations. RESULTS Athletes (n = 33) with clinically defined single or multiple concussions were compared to 91 age and gender matched controls without a history of concussion. AMPAR peptide values of 0.05-0.40 ng/mL for controls and 1.0-8.5 ng/mL for concussions are found. The biomarker sensitivity of 91% and a specificity of 92% (0.4 ng/mL cut off) to assess concussions are calculated. Poorer ImPACT scores correlated with abnormal levels of the biomarker. In athletes with multiple concussions, increased AMPAR peptide values (2.0-12.0 ng/mL) were associated with minor findings on magnetic resonance imaging. CONCLUSION AMPAR peptide assay combined with ImPACT and neuroimaging is a promising tool for assessment of concussions. Additional clinical validation studies are required.

Functional, Structural, and Neurotoxicity Biomarkers in Integrative Assessment of Concussions

Concussion is a complex, heterogeneous process affecting the brain. Accurate assessment and diagnosis and appropriate management of concussion are essential to ensure that athletes do not prematurely return to play or others to work or active military duty, risking re-injury. To date, clinical diagnosis relies primarily on evaluating subjects for functional impairment using instruments that include neurocognitive testing, subjective symptom report, and neurobehavioral assessments, such as balance and vestibular-ocular reflex testing. Structural biomarkers, defined as advanced neuroimaging techniques and biomarkers assessing neurotoxicity and immunoexcitotoxicity, may complement the use of functional biomarkers. We hypothesize that neurotoxicity AMPA, NMDA, and kainite receptor biomarkers might be utilized as a part of comprehensive approach to concussion evaluations, with the goal of increasing diagnostic accuracy and facilitating treatment planning and prognostic assessment.

Gradual Return to Play: Potential Role of Neurotoxicity Biomarkers inAssessment of Concussions Severity

This mini-review analyzes advantages and limitations of current methods of assessment of cerebral concussions considering functional, structural and metabolic factors in decision making for return to play. Novel neurotoxicity biomarkers, AMPA and NMDA receptor peptide/antibodies are proposed for evaluation of subtle brain injury following concussions. Neurotoxicity biomarkers can now be detected in the blood and are associated with severity of concussion and transient or persistent changes in the brain including diffuse axonal injury and microvascular dysfunction (edema formation). We surveyed 84 students (20.5 ± 2.5 years) participating in contact-sports and enrolled at Kennesaw State University. Based on neurotoxicity biomarkers values and diminished ImPACT scores, 18 athletes with concussions were selected for longitudinal assessment (1.5 year). Within the study, values of four neurotoxicity biomarkers decreased to normal in 11 (61%) concussed athletes while seven subjects maintained at least one acute and chronic biomarkers elevated reflecting structural changes in the brain defined by 3T DTI. It was demonstrated that neurotoxicity biomarkers in conjunction with neurocognitive testing might improve diagnostic certainty of suspected concussions. Additionally the use of biomarkers may provide valuable information on severity of concussions and help select subjects (about 2%) for advanced neuroimaging. Athletes with abnormal levels of neurotoxicity biomarkers and structural changes on DTI should be withheld from contact sports and be considered for therapeutic intervention and treatment to protect the brain from further neurological complications.

Chapter 9:Advances in Diagnostics and Treatment of Neurotoxicity after Sports-related Injuries

The neuronal and cerebral vascular impairments underlying neurotoxicity (excitotoxicity) due to mild traumatic brain injury are reviewed. Characteristic patterns of subtle injury in cortical, subcortical, or brainstem areas are associated with micro-, small-, and medium-sized artery dysfunctions. The present review is focused on trends in the choice of pharmacological and non-pharmacological approaches for mild traumatic brain injury therapy. These could optimize cerebral blood flow hemodynamics and homeostasis to protect executive brain functions and secure quality of life.

Chapter 12:Neurotoxicity in Spinal Cord Impairments

Spinal cord (SC) ischemia is a rare but devastating disorder caused by trauma and a wide range of diseases directly or indirectly affecting the SC vascular system. Specific biomarkers for SC ischemia combined with coherent guidelines could aid the early diagnosis of disease, target treatment development, and reduce mortality. The present chapter is devoted to the role of neurotoxicity cascade in the hemodynamics of SC impairment. Tendencies in early diagnosis and treatment of acute and chronic conditions are highlighted.

Acute Brain Impairment: Scientific Discoveries and Translational Research

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