Oral TNFα Modulation Alters Neutrophil Infiltration, Improves Cognition and Diminishes Tau and Amyloid Pathology in the 3xTgAD Mouse Model.

Cytokines such as TNFα can polarize microglia/macrophages into different neuroinflammatory types. Skewing of the phenotype towards a cytotoxic state is thought to impair phagocytosis and has been described in Alzheimer's Disease (AD). Neuroinflammation can be perpetuated by a cycle of increasing cytokine production and maintenance of a polarized activation state that contributes to AD progression. In this study, 3xTgAD mice, age 6 months, were treated orally with 3 doses of the TNFα modulating compound isoindolin-1,3 dithione (IDT) for 10 months. We demonstrate that IDT is a TNFα modulating compound both in vitro and in vivo. Following long-term IDT administration, mice were assessed for learning & memory and tissue and serum were collected for analysis. Results demonstrate that IDT is safe for long-term treatment and significantly improves learning and memory in the 3xTgAD mouse model. IDT significantly reduced paired helical filament tau and fibrillar amyloid accumulation. Flow cytometry of brain cell populations revealed that IDT increased the infiltrating neutrophil population while reducing TNFα expression in this population. IDT is a safe and effective TNFα and innate immune system modulator. Thus small molecule, orally bioavailable modulators are promising therapeutics for Alzheimer's disease.

Increased cerebrospinal fluid cleaved tau protein (C-tau) levels suggest axonal damage in pediatric patients with brain tumors.

OBJECTIVE: This study aims to determine if cerebrospinal fluid/serum cleaved tau protein and CSF 9-hydroxyoctadecadienoic acid levels, reflecting potential biomarkers of overall neuronal injury and lipid peroxidation, respectively, are elevated in brain tumor patients compared with controls. DESIGN: This article is a prospective clinical observational study. SETTING: This study is conducted at a tertiary-care children's hospital. PATIENTS: Our participants are children younger than or equal to 18 years of age undergoing brain tumor surgery. MEASUREMENTS AND MAIN RESULTS: During the study period, 26 consecutive patients newly diagnosed with brain tumors who met the inclusion criteria were prospectively enrolled. Baseline cerebrospinal fluid analysis of cleaved tau and 9-hydroxyoctadecadienoic acid were measured in 15 patients. Cerebrospinal fluid cleaved tau and 9-hydroxyoctadecadienoic acid levels were measured in 22 patients for post-surgery days 1 and 3. Serum cleaved tau levels were measured for 20 and 18 patients for post-surgery days 1 and 3, respectively. The presence of a brain tumor significantly increased the baseline cerebrospinal fluid cleaved tau levels but did not affect cerebrospinal fluid 9-hydroxyoctadecadienoic acid levels. Similarly, there was a significant increase in post-surgery day 1 cerebrospinal fluid cleaved tau levels from baseline (p = 0.01) and a trend toward significant decrease in post-surgery day 3 cerebrospinal fluid cleaved tau from day 1 (p = 0.07). 9-Hydroxyoctadecadienoic acid concentrations remained relatively constant over time with no differences noted between the control and brain tumor patients. There was a trend towards a significant association between cerebrospinal fluid cleaved tau levels and duration of symptoms (p = 0.07). CONCLUSIONS: Cerebrospinal fluid cleaved tau levels in children with newly diagnosed brain tumors exhibit markedly elevated cerebrospinal fluid cleaved tau levels, suggesting axonal damage. This axonal injury does not seem to correlate with lipid peroxidation at least when as assessed by cerebrospinal fluid 9-hydroxyoctadecadienoic acid levels. There was no association found between the biomarkers and multiple independent variables obtained at pre- and post-tumor resection.

Safety, tolerability and pharmacokinetics of 2-pyridylacetic acid, a major metabolite of betahistine, in a phase 1 dose escalation study in subjects with ADHD.

Betahistine, a potent histamine H3 receptor antagonist, is being developed for the treatment of attention deficit hyperactivity disorder (ADHD) that manifests with symptoms such as hyperactivity, impulsivity and inattention. This study describes the pharmacokinetics of betahistine in ADHD subjects at doses higher than 50 mg. These assessments were made during a randomized, placebo-controlled, single blind, dose escalation study to determine the safety, tolerability and pharmacokinetics of once daily doses of 50 mg, 100 mg and 200 mg of betahistine in subjects with ADHD. Plasma levels of 2-pyridylacetic acid (2-PAA), a major metabolite of betahistine were quantified using a validated LC-MS/MS method and used for pharmacokinetic analysis and dose proportionality of betahistine. A linear relationship was observed in Cmax and AUC0-4 of 2-PAA with the betahistine dose (R2 0.9989 and 0.9978, respectively) and dose proportionality coefficients (ß) for the power model were 0.8684 (Cmax) and 1.007 (AUC0-4). A population pharmacokinetic model with first-order absorption of betahistine and metabolism to 2-PAA, followed by a first-order elimination of 2-PAA provides estimates of clearance that underscored the linear increase in systemic exposure with dose. There were no serious adverse events reported in the study, betahistine was safe and well tolerated at all the dose levels tested.

A selective dopamine reuptake inhibitor improves prefrontal cortex-dependent cognitive function: potential relevance to attention deficit hyperactivity disorder.

Drugs used to treat attention deficit hyperactivity disorder (ADHD) improve prefrontal cortex (PFC)-dependent cognitive function. The majority of ADHD-related treatments act either as dual norepinephrine (NE) and dopamine (DA) reuptake inhibitors (psychostimulants) or selective NE reuptake inhibitors (SNRIs). Certain benztropine analogs act as highly selective DA reuptake inhibitors while lacking the reinforcing actions, and thus abuse potential, of psychostimulants. To assess the potential use of these compounds in the treatment of ADHD, we examined the effects of a well-characterized benztropine analog, AHN 2-005, on performance of rats in a PFC-dependent delayed-alternation task of spatial working memory. Similar to that seen with all drugs currently approved for ADHD, AHN 2-005 dose-dependently improved performance in this task. Clinically-relevant doses of psychostimulants and SNRIs elevate NE and DA preferentially in the PFC. Despite the selectivity of this compound for the DA transporter, additional microdialysis studies demonstrated that a cognition-enhancing dose of AHN 2-005 that lacked locomotor activating effects increased extracellular levels of both DA and NE in the PFC. AHN 2-005 produced a larger increase in extracellular DA in the nucleus accumbens, although the magnitude of this was well below that seen with motor activating doses of psychostimulants. Collectively, these observations suggest that benztropine analogs may be efficacious in the treatment of ADHD or other disorders associated with PFC dysfunction. These studies provide a strong rationale for future research focused on the neural mechanisms contributing to the cognition-enhancing actions and the potential clinical utility of AHN 2-005 and related compounds. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

Early intervention with a small molecule inhibitor for tumor necrosis factor-α prevents cognitive deficits in a triple transgenic mouse model of Alzheimer's disease.

BACKGROUND: Chronic neuroinflammation is an important component of Alzheimer's disease and could contribute to neuronal dysfunction, injury and loss that lead to disease progression. Multiple clinical studies implicate tumor necrosis factor-α as an inflammatory mediator of neurodegeneration in patients with Alzheimer's because of elevated levels of this cytokine in the cerebrospinal fluid, hippocampus and cortex. Current Alzheimer's disease interventions are symptomatic treatments with limited efficacy that do not address etiology. Thus, a critical need exists for novel treatments directed towards modifying the pathophysiology and progression. METHODS: To investigate the effect of early immune modulation on neuroinflammation and cognitive outcome, we treated triple transgenic Alzheimer's disease mice (harboring PS1(M146V), APP(Swe), and tau(P301L) transgenes) with the small molecule tumor necrosis factor-α inhibitors, 3,6'-dithiothalidomide and thalidomide, beginning at four months of age. At this young age, mice do not exhibit plaque or tau pathology but do show mild intraneuronal amyloid beta protein staining and a robust increase in tumor necrosis factor-α. After 10 weeks of treatment, cognitive performance was assessed using radial arm maze and neuroinflammation was assessed using biochemical, stereological and flow cytometric endpoints. RESULTS: 3,6'-dithiothalidomide reduced tumor necrosis factor-α mRNA and protein levels in the brain and improved working memory performance and the ratio of resting to reactive microglia in the hippocampus of triple transgenic mice. In comparison to non-transgenic controls, triple transgenic Alzheimer's disease mice had increased total numbers of infiltrating peripheral monomyelocytic/granulocytic leukocytes with enhanced intracytoplasmic tumor necrosis factor-α, which was reduced after treatment with 3,6'-dithiothalidomide. CONCLUSIONS: These results suggest that modulation of tumor necrosis factor-α with small molecule inhibitors is safe and effective with potential for the long-term prevention and treatment of Alzheimer's disease.

Serum cleaved tau does not predict postconcussion syndrome after mild traumatic brain injury.

OBJECTIVES: Our objective was to determine if the biomarker for axonal injury, serum cleaved tau (C-tau), predicts postconcussion syndrome (PCS) in adults after mild traumatic brain injury (mTBI). METHODS: C-tau was measured from blood obtained in the emergency department. Outcome was assessed at 3 months post injury using the Rivermead Postconcussion Symptoms Questionnaire and Acute Medical Outcomes SF-36v2 Health Survey (SF-36). RESULTS: Of 50 patients, there were 15 patients with detectable levels of C-tau, 10 patients with abnormal findings on initial head computed tomography (CT) and 22 patients with PCS. One-third of patients with detectable C-tau and 14.3% of patients without detectable C-tau had abnormal findings on head CT (P = .143). Serum C-tau was not detected more frequently in patients with PCS than those without, neither for all patients (P = .115) nor the subgroup with negative head CT (P = .253). CONCLUSIONS: C-tau is a poor predictor of PCS after mTBI regardless of head CT result.

Cerebrospinal fluid cleaved-tau protein and 9-hydroxyoctadecadienoic acid concentrations in pediatric patients with hydrocephalus.

OBJECTIVE: To ascertain if cerebrospinal fluid cleaved-tau protein and 9-hydroxyoctadecadienoic acid, reflecting potential biomarkers of overall neuronal injury and lipid peroxidation, respectively, are elevated in hydrocephalus patients compared with controls, and if cleaved-tau and 9-hydroxyoctadecadienoic acid levels correlate with each other. DESIGN: Prospective clinical observational study. SETTING: Tertiary-care children's hospital. PATIENTS: Children younger than or equal to 18 yrs who underwent ventriculoperitoneal shunt placement or revision surgery for intrinsic hydrocephalus. MEASUREMENTS AND MAIN RESULTS: During the study period 12 patients with intrinsic hydrocephalus required ventriculoperitoneal shunt placement or revision. Cerebrospinal fluid cleaved-tau levels were significantly elevated in patients with hydrocephalus (44.7 +/- 9.6 ng/mL, n = 11) compared with control patients (0.0 +/- 0.0 ng/mL, n = 9; p < 0.0001). Cleaved-tau levels correlated with patient age (r = .609, p = 0.047) and duration of symptoms (r = .755, p = 0.007). No significant difference in cerebrospinal fluid 9-hydroxyoctadecadienoic acid levels between patients with hydrocephalus (24.6 +/- 5.7, n = 8) and control patients (24.9 +/- 9.3 ng/mL, n = 7) was detected (p = 0.25). There was also no statistically significant correlation between 9-hydroxyoctadecadienoic acid levels and duration of symptoms (r = .668, p = 0.07), nor was there a significant correlation between 9-hydroxyoctadecadienoic acid levels and patient age (r = -.011, p > 0.10). There was no significant relationship between 9-hydroxyoctadecadienoic acid levels and signs of elevated intracranial pressure, nor was there a correlation between 9-hydroxyoctadecadienoic acid levels and cleaved-tau levels. CONCLUSION: Children with hydrocephalus who have clinical signs of increased intracranial pressure and require ventriculoperitoneal shunt placement or revision exhibit markedly elevated cerebrospinal fluid cleaved-tau levels, suggesting evidence of axonal damage. However, this axonal injury does not seem to be associated with significant lipid peroxidation, at least as assessed by quantifying cerebrospinal fluid 9-hydroxyoctadecadienoic acid at a single, concurrent time point. The significant relationship between age and cerebrospinal fluid cleaved-tau levels suggest that brain injury associated with hydrocephalus may be more pronounced in older children.

Serum S-100B and cleaved-tau are poor predictors of long-term outcome after mild traumatic brain injury.

PRIMARY OBJECTIVE: To determine the relationship of serum S-100B and C-tau levels to long-term outcome after mild traumatic brain injury (mild TBI). RESEARCH DESIGN: A prospective study of 35 mild TBI subjects presenting to the emergency department. METHODS AND PROCEDURES: Six hour serum S-100B and C-tau levels compared to 3-month Rivermead Post Concussion Questionnaire (RPCQ) scores and post-concussive syndrome (PCS). MAIN OUTCOMES AND RESULTS: The linear correlation between marker levels and RPCQ scores was weak (S-100B: r = 0.071, C-tau: r = -0.21). There was no statistically significant correlation between marker levels and 3-month PCS (S-100B: AUC = 0.589, 95%CI. 038, 0.80; C-tau: AUC = 0.634, 95%CI 0.43, 0.84). The sensitivity of these markers ranged from 43.8-56.3% and the specificity from 35.7-71.4%. CONCLUSIONS: Initial serum S-100B and C-tau levels appear to be poor predictors of 3-month outcome after mild TBI.

The efficacy and safety of the melatonin agonist beta-methyl-6-chloromelatonin in primary insomnia: a randomized, placebo-controlled, crossover clinical trial.

BACKGROUND: While melatonin agonists are known to regulate circadian sleep rhythms, it is not clear whether melatonin agonists have a direct soporific effect. It has been suggested that melatonin's soporific effect is secondary to its ability to induce hypothermia. beta-Methyl-6-chloromelatonin is a high-affinity melatonin receptor agonist that is not associated with hypothermia. The purpose of the present study was to determine if the melatonin agonist beta-methyl-6-chloromelatonin has a direct soporific effect in subjects with primary insomnia. METHOD: A double-blind, placebo-controlled, crossover safety and efficacy study of 20 mg, 50 mg, and 100 mg of beta-methyl-6-chloromelatonin and placebo was conducted in subjects with DSM-IV-TR primary insomnia. Of 84 subjects screened, 40 progressed to randomly receive each of 3 beta-methyl-6-chloromelatonin doses or placebo on each of 2 consecutive nights with 5-day washout periods between treatments. The effect of treatment on both polysomnographic and subjectively measured sleep parameters, next-morning psychomotor performance, and safety measures was determined. The primary outcome measure was latency to persistent sleep measured by polysomnography. RESULTS: A significant effect of beta-methyl-6-chloromelatonin on the primary efficacy variable, latency to persistent sleep, was observed (p = .0003). The 20-mg dose resulted in a significant 31% improvement in sleep latency compared with placebo, while significant 32% and 41% improvements were observed at the 50-mg and 100-mg doses, respectively (20 mg, p = .0082; 50 mg, p = .0062; 100 mg, p < .0001). Similarly, a significant effect of beta-methyl-6-chloromelatonin on subjective measures of time to fall asleep occurred (p = .0050), with significant improvement observed at both the 50-mg and 100-mg doses (p = .0350 and .0198, respectively) and a trend toward improvement observed at the 20-mg dose (p = .0582). Adverse events were mild to moderate in severity and did not differ in frequency between beta-methyl-6-chloromelatonin and placebo treatments. CONCLUSION: beta-Methyl-6-chloromelatonin significantly decreases both objective and subjective measures of sleep latency in subjects with primary insomnia. Thus, these data suggest that mel-atonin agonists may exert a direct soporific effect, as previous research indicates that beta-methyl-6-chloromelatonin is not associated with changes in body temperature, heart rate, or blood pressure.

Cleaved-tau: a biomarker of neuronal damage after traumatic brain injury.

Previous studies from our laboratory indicate that traumatic brain injury (TBI) in humans results in proteolysis of neuronally-localized, intracellular microtubule associated protein (MAP)-tau to produce cleaved tau (C-tau). The present study evaluated the utility of C-tau to function as a biomarker of neuronal injury and as a biomarker for evaluating neuroprotectant drug efficacy in a controlled cortical impact model of rat TBI. Brain C-tau was determined in rats subjected to controlled cortical impact-induced mild, moderate or severe levels of TBI. A significant severity-dependent increase in C-tau levels was observed in the cortex and hippocampus (1.5-8-fold) of TBI rats compared to shams 72 h after impact. C-tau rat brain and serum time course was determined by measuring levels at 0.25, 6, 24, 48, 72 and 168 h after TBI. A significant time-dependent increase in C-tau levels was observed in ipsilateral cortex (5-16-fold) and hippocampus (2-40-fold) compared to sham animals. C-tau levels increased as early as 6 h after TBI with peak C-tau levels observed 168 h after injury. Elevated brain C-tau levels were associated with TBI-induced tissue loss, which was histologically determined. The effect of cyclosporin-A (CsA), previously demonstrated to be neuroprotective in rat TBI, on brain C-tau levels was examined. CsA (20 mg/kg i.p., 15 min and 24 h after TBI) significantly attenuated the TBI-induced increase in hippocampal C-tau levels observed in vehicle-treated animals confirming CsA's neuroprotectant effect. CsA treatment also lowered ipsilateral cortical C-tau levels, although it did not reach statistical significance. CsA's neuroprotectant effect was confirmed utilizing histologic measures of TBI-induced tissue loss. In addition, serum C-tau levels were significantly increased 6 h after TBI but not at later time points. These results suggest that C-tau is a reliable, quantitative biomarker for evaluating TBI-induced neuronal injury and a potential biomarker of neuroprotectant drug efficacy in the rat TBI model. Serum data suggests that C-tau levels are dependent both on a compromised blood-brain barrier as well as release of TBI biomarkers from the brain, which has implications for the study of human serum TBI biomarkers.

Dexamethasone decreases neurological sequelae and caspase activity.

OBJECTIVE: To evaluate the use of dexamethasone in a model of meningitis-induced brain injury. Changes in neurobehavioral performance were the primary outcome variables. Changes in caspase activation and markers of neuronal injury were the secondary outcome variables. DESIGN: Randomized, prospective animal study. SETTING: University research laboratory. SUBJECTS: Male Wistar rats. INTERVENTIONS: Animals underwent a basilar cistern injection of either placebo or a suspension of Group B Streptococcus. Sixteen hours after inoculation, animals were randomized and received either dexamethasone or placebo in addition to antibiotics. Neurobehavioral performance and biological markers of brain injury were assessed at 3 days and 9 days after randomization. In a second experiment, caspase 1 and 3 were evaluated at 6 h, 24 h, and 72 h after dexamethasone administration. MEASUREMENTS AND MAIN RESULTS: Neurobehavioral performance at 3 days and 9 days was significantly improved in the dexamethasone group. Serum C-tau and cerebral edema were decreased after 3 days of dexamethasone treatment. Dexamethasone decreased Caspase 3 activation in meningitic animals. CONCLUSION: These findings demonstrate that dexamethasone decreases acute brain injury in a rat model of bacterial meningitis as measured by preservation of neurobehavioral performance.

The arachidonic acid 5-lipoxygenase inhibitor nordihydroguaiaretic acid inhibits tumor necrosis factor alpha activation of microglia and extends survival of G93A-SOD1 transgenic mice.

Familial forms of amyotrophic lateral sclerosis (ALS) can be caused by mutations in copper, zinc-superoxide dismutase (SOD1). Mice expressing SOD1 mutants demonstrate a robust neuroinflammatory reaction characterized, in part, by up-regulation of tumor necrosis factor alpha (TNFalpha) and its primary receptor TNF-RI. In an effort to identify small molecule inhibitors of neuroinflammation useful in treatment of ALS, a microglial culture system was established to identify TNFalpha antagonists. Walker EOC-20 microglia cells were stimulated with recombinant TNFalpha, with or without inhibitors, and the cell response was indexed by NO2- output. Three hundred and fifty-five rationally selected compounds were included in this bioassay. The arachidonic acid 5-lipoxygenase (5LOX) and tyrosine kinase inhibitor nordihydroguaiaretic acid (NDGA), a natural dicatechol, was one of the most potent non-cytotoxic antagonists tested (IC50 8 +/- 3 microm). Investigation of the G93A-SOD1 mouse model for ALS revealed increased message and protein levels of 5LOX at 120 days of age. Oral NDGA (2500 p.p.m.) significantly extended lifespan and slowed motor dysfunction in this mouse, when administration was begun relatively late in life (90 days). NDGA extended median total lifespan of G93A-SOD1 mice by 10%, and life expectancy following start of treatment was extended by 32%. Disease-associated gliosis and cleaved microtubule-associated tau protein, an indicator of axon damage, were likewise reduced by NDGA. Thus, TNFalpha antagonists and especially 5LOX inhibitors might offer new opportunities for treatment of ALS.

Modulation of nuclear factor-kappaB activation and decreased markers of neurological injury associated with hypothermic therapy in experimental bacterial meningitis.

OBJECTIVE: This study was designed to evaluate the use of moderate hypothermia in a model of meningitis-induced brain injury and its effect on the activation of nuclear factor-kappaB, biological markers of neuronal injury, and neurobehavioral performance. DESIGN: Randomized, prospective animal study. SETTING: University research laboratory. SUBJECTS: Male Wistar rats. INTERVENTIONS: Animals underwent a basilar cistern tap receiving either sterile saline as a placebo or an equivalent volume of a group B streptococcal suspension. Sixteen hours after inoculation, animals were stratified by their clinical severity score, were randomized to either hypothermic (32-34 degrees C) or normothermic (37-39 degrees C) conditions, and received antibiotics. Hypothermic animals were kept under these temperature conditions for 6 hrs before rewarming. Two protocols were used. For the first protocol, changes in nuclear factor-kappaB activation and heat shock protein induction at 24 hrs and 48 hrs after inoculation were evaluated. In the second protocol, serum C-tau concentrations at 5 days and neurobehavioral performances at 3 wks were assessed. MEASUREMENTS AND MAIN RESULTS: Meningitis triggered a >50% increase in cerebral nuclear factor-kappaB activation. The addition of a 6-hr period of hypothermia reduced nuclear factor-kappaB activation by 32% when measured at the end of the hypothermic period. At 48 hrs, this decrease in nuclear factor-kappaB activation was no longer apparent, but there was a significant decrease in the heat shock response. Serum C-tau concentrations at 5 days postinjury, a biomarker of brain injury, were reduced by 69% in hypothermic treated animals. Furthermore, hypothermia reduced the brain water content of infected animals. However, hypothermia did not improve the animals' neurobehavioral performance. CONCLUSION: The findings from this study suggest that hypothermia produces a transitory attenuation of nuclear factor-kappaB activation in meningitic brain injury and improvement in some biomarkers of neuronal injury. The consequence of intermittent suppression of nuclear factor-kappaB activation by inducing specific periods of hypothermia requires further study.

C-tau biomarker of neuronal damage in severe brain injured patients: association with elevated intracranial pressure and clinical outcome.

Following traumatic brain injury, the neuronally-localized intracellular protein MAP-tau is proteolytically cleaved (C-tau) and gains access to cerebrospinal fluid (CSF) and serum. The present study compared initial CSF C-tau levels, initial Glasgow Coma Scale (GCS) scores and elevated intracranial pressure (ICP) as predictors of clinical outcome. In this preliminary, prospective study of consecutive severe traumatic brain injured patients (TBI) clinical outcome was quantified with the Glasgow Outcome Scale (GOS) at discharge (n=28). Sensitivity and specificity of initial C-tau levels and initial GCS scores as predictors of clinical outcome is reported. To assess disease specificity C-tau levels were compared between TBI patients and neurologic (n=87) and non-neurologic control patients (n=67). Initial CSF C-tau levels were elevated 40,000 fold in TBI patients compared to either neurologic or non-neurologic control patients (P<0.001). Initial C-tau levels were correlated with clinical outcome (P=0.006) and were a significant predictor of dichotomized clinical outcome (P=0.011) demonstrating a sensitivity of prediction of 92% and a specificity of 94%. Initial C-tau levels were also a significant predictor of subsequent ICP with higher initial C-tau levels associated with elevated ICP (P=0.014). Initial GCS score were correlated with clinical outcome (P=0.026) and demonstrated a sensitivity of 50% and a specificity of 100% for predicting dichotomized clinical outcome. Statistical analysis indicated that initial C-tau levels and initial GCS scores were independent predictors of clinical outcome. The present preliminary study demonstrates that initial CSF C-tau levels are a significant predictor of ICP and clinical outcome with particular sensitivity for identifying severe TBI patients with good clinical outcome. Future studies employing a larger sample size and clinical outcome assessment at longer periods after hospitalization will be needed to determine the utility of initial C-tau levels as a clinical biomarker in TBI.

Serum cleaved tau protein levels and clinical outcome in adult patients with closed head injury.

STUDY OBJECTIVE: Intracranial injuries (ICI) are associated with high mortality and morbidity. Unfortunately, tools for diagnosis and risk stratification of ICIs are limited in the emergency department setting. We determine the relationship between the presence or absence of a detectable cleaved serum tau protein (tau(c)), ICI, and outcome at hospital discharge in adults with closed head injuries (CHI). METHODS: This was a prospective pilot study of adult patients with CHI presenting to the ED of an urban Level I trauma center. Patients presenting within 10 hours of a CHI who underwent a head computed tomographic (CT) scan were eligible. A blood sample was collected at presentation and the tau(c) level was measured. Initial Glasgow Coma Scale scores and demographic information were recorded. A chart review was performed to determine outcome and final readings on the initial head CT scan. RESULTS: Patients were dichotomized to 1 of 2 groups, those with an ICI (n=17) and those with an isolated skull fracture or no CT abnormality (NICI) (n=11). The 2 groups were similar in regard to demographic composition, mechanism of injury, and coexisting injuries. A tau(c) level of more than 0 was associated with an increased chance of an ICI on the initial head CT scan (odds ratio 11.25; 95% confidence interval [CI] 1.17 to 108.4) and a greater chance of poor outcome, defined as death while in hospital or transfer to a nursing home at hospital discharge (odds ratio 8.17; 95% CI 1.42 to 47). CONCLUSION: A tau(c) level of more than 0 is associated with a greater chance of intracranial injury and poor outcome in patients with CHI.

Analgesia after lesions of nucleus reticularis magnocellularis: differential effect on supraspinal versus spinal pain reflexes.

The present studies examine the effect of bilateral electrolytic lesions of descending fibers arising from nucleus reticularis magnocellularis (NMC) on responding to noxious peripheral thermal or mechanical stimulation and on spinal cord monoamine levels. The lesion effects were quantified by examining two supraspinally organized pain responses, the hot plate latency and vocalization threshold and two spinally organized nociceptive reflexes, tail flick latency and hind limb flexion threshold. Following interruption of descending NMC fibers, a profound analgesia was observed on supraspinally organized pain responses. Assay of spinal cord serotonin (5-HT) indicated that the NMC lesions also destroyed appreciable numbers of descending 5-HT fibers of passage originating in nucleus raphe magnus (RM). A modest hypersensitivity to pain occurred after control lesions in RM suggesting that the analgesia observed after NMC lesions would have been even more pronounced if RM fibers of passage had not been concomitantly destroyed. To assess whether the analgesia observed after NMC lesions was due to non-specific destruction of a given volume of reticular tissue, control lesions were placed in nucleus subcoeruleus (NSC). NSC lesions resulted in a hypersensitivity to pain and significant depletion of spinal cord noradrenaline (NA). These data suggest both that the analgesia observed after NMC lesions was not due to non-specific destruction of the reticular formation, and that descending NSC NA fibers tonically suppress pain. The above analgesic effects were observed exclusively on supraspinally organized pain responses, not spinally organized nociceptive reflexes. This supported previous studies demonstrating differential descending control of nociception in the spinal versus intact preparations. In summary, the present data suggest that descending NMC fibers tonically suppress ascending pain transmission.