Axonal injury following mild traumatic brain injury is exacerbated by repetitive insult and is linked to the delayed attenuation of NeuN expression without concomitant neuronal death in the mouse.

Mild traumatic brain injury (mTBI) affects brain structure and function and can lead to persistent abnormalities. Repetitive mTBI exacerbates the acute phase response to injury. Nonetheless, its long-term implications remain poorly understood, particularly in the context of traumatic axonal injury (TAI), a player in TBI morbidity via axonal disconnection, synaptic loss and retrograde neuronal perturbation. In contrast to the examination of these processes in the acute phase of injury, the chronic-phase burden of TAI and/or its implications for retrograde neuronal perturbation or death have received little consideration. To critically assess this issue, murine neocortical tissue was investigated at acute (24-h postinjury, 24hpi) and chronic time points (28-days postinjury, 28dpi) after singular or repetitive mTBI induced by central fluid percussion injury (cFPI). Neurons were immunofluorescently labeled for NeuroTrace and NeuN (all neurons), p-c-Jun (axotomized neurons) and DRAQ5 (cell nuclei), imaged in 3D and quantified in automated manner. Single mTBI produced axotomy in 10% of neurons at 24hpi and the percentage increased after repetitive injury. The fraction of p-c-Jun+ neurons decreased at 28dpi but without neuronal loss (NeuroTrace), suggesting their reorganization and/or repair following TAI. In contrast, NeuN+ neurons decreased with repetitive injury at 24hpi while the corresponding fraction of NeuroTrace+ neurons decreased over 28dpi. Attenuated NeuN expression was linked exclusively to non-axotomized neurons at 24hpi which extended to the axotomized at 28dpi, revealing a delayed response of the axotomized neurons. Collectively, we demonstrate an increased burden of TAI after repetitive mTBI, which is most striking in the acute phase response to the injury. Our finding of widespread axotomy in large fields of intact neurons contradicts the notion that repetitive mTBI elicits progressive neuronal death, rather, emphasizing the importance of axotomy-mediated change.

Intensity Specific Repetitive Mild Traumatic Brain Injury Evokes an Exacerbated Burden of Neocortical Axonal Injury.

Mild traumatic brain injury (mTBI) has been linked to enduring neurological damage following repetitive injury. Previously, we reported that intensity-specific, repetitive mTBI exacerbated microvascular and axonal damage in brainstem. For a more rigorous and global assessment, we assessed the burden of neocortical diffuse axonal injury (DAI) evoked by repetitive mTBI. Mice were subjected to mild central fluid percussion injuries at 1.4 and 1.6 atm with or without repetitive insult at a 3-hour interval and killed at 24 hours postinjury. Neocortical DAI within layer V was quantitatively assessed by double-labeling p-c-Jun and NeuN to identify both the axotomized and total neuronal population. Both confocal and electron microscopic findings revealed no apparent evidence of neuronal death. Repetitive mTBI of 1.6 atm group, but not of 1.4 atm group, demonstrated a significantly higher proportion of axotomized neurons. These results demonstrate that different intensities of mTBI induced different burdens of DAI after repetitive insult. Interestingly, the parallel loss of the righting reflex reflected differences in injury intensity, yet the duration of this reflex was not elongated by the repetitive insult. These data highlight some of the complex issues surrounding repetitive mTBI and its associated morbidity, mandating the need for continued exploration.

Serum neutrophil gelatinase-associated lipocalin levels predict the neurological outcomes of out-of-hospital cardiac arrest victims.

BACKGROUND: Serum neutrophil gelatinase-associated lipocalin (NGAL) is a well-known biomarker of acute kidney injury. Serum NGAL was recently proposed as a potential predictor of mortality in post cardiac arrest syndrome (PCAS) patients following out-of-hospital cardiac arrest (OHCA). However, the potential predictive value of NGAL for neurological outcomes is unknown. Therefore, we assessed the potential predictive value of NGAL for neurological outcomes after OHCA. We also compared its predictive value with that of neuron-specific enolase (NSE) as an established biomarker. METHODS: Blood samples were prospectively collected from 43 PCAS patients following OHCA. Serum NGAL was measured on days 1 and 2, and NSE was measured on day 2. These biomarkers were compared between patients with favourable (cerebral performance category [CPC] 1-2) and unfavourable (CPC 3-5) outcomes. Receiver operating characteristic (ROC) curve analysis was performed. RESULTS: Serum NGAL and NSE on day 2 (both P < 0.001), but not NGAL on day 1 (P = 0.609), were significantly different between the favourable and unfavourable groups. In ROC curve analysis, the sensitivity and specificity were 83% and 85%, respectively, for NGAL (day 2) at a cutoff value of 204 ng/mL and were 84% and 100% for NSE (day 2) at a cutoff value of 28.8 ng/mL. The area under the ROC curve of NGAL (day 2) was equivalent to that of NSE (day 2) (0.830 vs. 0.918). Additionally, the area under the ROC curve in subgroup of estimated glomerular filtration rate (eGFR) > 20 mL/min/1.73 m2 (n = 38, 0.978 vs. 0.923) showed the potential of NGAL predictability. CONCLUSIONS: Serum NGAL might predict the neurological outcomes of PCAS patients, and its predictive value was equivalent to that of NSE.

Development of a prompt model for predicting neurological outcomes in patients with return of spontaneous circulation from out-of-hospital cardiac arrest.

Aim: Early prediction of the neurological outcomes of patients with out-of-hospital cardiac arrest is important to select the optimal clinical management. We hypothesized that clinical data recorded at the site of cardiopulmonary resuscitation would be clinically useful. Methods: This retrospective cohort study included patients with return of spontaneous circulation after cardiopulmonary resuscitation who were admitted to our university hospital between January 2000 and November 2013 or two affiliated hospitals between January 2006 and November 2013. Clinical parameters recorded on arrival included age (A), arterial blood pH (B), time from cardiopulmonary resuscitation to return of spontaneous circulation (C), pupil diameter (D), and initial rhythm (E). Glasgow Outcome Scale was recorded at 6 months and a favorable neurological outcome was defined as a score of 4-5 on the Glasgow Outcome Scale. Multiple logistic regression analysis was carried out to derive a formula to predict neurological outcomes based on basic clinical parameters. Results: The regression equation was derived using a teaching dataset (total, n = 477; favourable outcome, n = 55): EP = 1/(1 + e-x ), where EP is the estimated probability of having a favorable outcome, and x = (-0.023 × A) + (3.296 × B) - (0.070 × C) - (1.006 × D) + (2.426 × E) - 19.489. The sensitivity, specificity, and accuracy were 80%, 92%, and 90%, respectively, for the validation dataset (total, n = 201; favourable outcome, n = 25). Conclusion: The 6-month neurological outcomes can be predicted in patients resuscitated from out-of-hospital cardiac arrest using clinical parameters that can be easily recorded at the site of cardiopulmonary resuscitation.

Prevalence and associated factors for delirium in critically ill patients at a Japanese intensive care unit.

OBJECTIVE: To investigate the prevalence and associated factors of delirium in critically ill patients during an intensive care unit (ICU) stay. METHODS: We investigated 103 of 172 patients admitted consecutively to a university-based 20-bed ICU in a 3-month period. Six ICU physicians, who were familiar with the Confusion Assessment Method for the ICU (CAM-ICU), assessed patient delirium daily. Patient demographics, diagnosis, Acute Physiology and Chronic Health Evaluation (APACHE) II score, mechanical ventilation and maximum serum C-reactive protein (max-CRP) level during the ICU stay (max-CRP) were compared between patients who developed delirium and those who did not. RESULTS: Twenty-one (20%) of 103 patients and 13 (76%) of 17 mechanically ventilated patients developed delirium. APACHE II scores and max-CRP were significantly higher in patients who experienced delirium than in those who did not (P<.001). Use of a mechanical ventilator (P=.002), max-CRP (P=.032) and length of ICU stay (P=.043) were identified as independent associations for delirium development. CONCLUSIONS: The prevalence of delirium was 20% in ICU patients and 80% in ventilated patients in a Japanese ICU.

Cholinergic agonist physostigmine suppresses excessive superoxide anion radical generation in blood, oxidative stress, early inflammation, and endothelial injury in rats with forebrain ischemia/reperfusion.

The cholinergic anti-inflammatory pathway is reportedly important in modulating the inflammatory response in local and systemic diseases, including ischemia/reperfusion pathophysiology. In this study, we investigated the effects of the cholinergic agonist, physostigmine, on jugular venous superoxide radical (O(2)(-)) generation, oxidative stress, early inflammation, and endothelial activation during forebrain ischemia/reperfusion (FBI/R) in rats. Fourteen male Wistar rat were allocated to the control group (n=7) or physostigmine group (n=7). The physostigmine group received 80 ng/g physostigmine intraperitoneally 24 h and 1 h before forebrain ischemia was established. The jugular venous O(2)(-) current was measured for 10 min during forebrain ischemia and for 120 min after reperfusion. The O(2)(-) current increased gradually during forebrain ischemia in both groups. The current increased markedly immediately after reperfusion in the control group but was significantly attenuated in the physostigmine group after reperfusion. Brain and plasma malondialdehyde, high-mobility group box 1 (HMGB1) protein, and intercellular adhesion molecule 1 (ICAM1) were significantly attenuated in the physostigmine group compared with the control group, except for brain HMGB1. The amount of O(2)(-) generated during FBI/R correlated with malondialdehyde, HMGB1, and ICAM1 in both the brain and plasma. In conclusion, the cholinergic agonist physostigmine suppressed jugular venous O(2)(-) generation, oxidative stress, early inflammation, and endothelial activation in the brain and plasma in the acute phase of cerebral ischemia/reperfusion. Therefore, the suppression of O(2)(-) is a key mechanism of the cholinergic anti-inflammatory pathway in the pathophysiology of cerebral ischemia/reperfusion.