Brain Injury Articles 4

© 2012

Retinoic acid restores adult hippocampal neurogenesis and reverses spatial memory deficit in vitamin A deprived rats

            (Bonnet, Touyarot et al. 2008) Download

A dysfunction of retinoid hippocampal signaling pathway has been involved in the appearance of affective and cognitive disorders. However, the underlying neurobiological mechanisms remain unknown. Hippocampal granule neurons are generated throughout life and are involved in emotion and memory. Here, we investigated the effects of vitamin A deficiency (VAD) on neurogenesis and memory and the ability of retinoic acid (RA) treatment to prevent VAD-induced impairments. Adult retinoid-deficient rats were generated by a vitamin A-free diet from weaning in order to allow a normal development. The effects of VAD and/or RA administration were examined on hippocampal neurogenesis, retinoid target genes such as neurotrophin receptors and spatial reference memory measured in the water maze. Long-term VAD decreased neurogenesis and led to memory deficits. More importantly, these effects were reversed by 4 weeks of RA treatment. These beneficial effects may be in part related to an up-regulation of retinoid-mediated molecular events, such as the expression of the neurotrophin receptor TrkA. We have demonstrated for the first time that the effect of vitamin A deficient diet on the level of hippoccampal neurogenesis is reversible and that RA treatment is important for the maintenance of the hippocampal plasticity and function.

Vitamin D2 potentiates axon regeneration

            (Chabas, Alluin et al. 2008) Download

To date, the use of autograft tissue remains the "gold standard" technique for repairing transected peripheral nerves. However, the recovery is suboptimal, and neuroactive molecules are required. In the current study, we focused our attention on vitamin D, an FDA-approved molecule whose neuroprotective and neurotrophic actions are increasingly recognized. We assessed the therapeutic potential of ergocalciferol--the plant-derived form of vitamin D, named vitamin D2--in a rat model of peripheral nerve injury and repair. The left peroneal nerve was cut out on a length of 10 mm and immediately autografted in an inverted position. After surgery, animals were treated with ergocalciferol (100 IU/kg/day) and compared to untreated animals. Functional recovery of hindlimb was measured weekly, during 10 weeks post-surgery, using a walking track apparatus and a numerical camcorder. At the end of this period, motor and sensitive responses of the regenerated axons were calculated and histological analysis was performed. We observed that vitamin D2 significantly (i) increased axogenesis and axon diameter; (ii) improved the responses of sensory neurons to metabolites such as KCl and lactic acid; and (iii) induced a fast-to-slow fiber type transition of the Tibialis anterior muscle. In addition, functional recovery was not impaired by vitamin D supplementation. Altogether, these data indicate that vitamin D potentiates axon regeneration. Pharmacological studies with various concentrations of the two forms of vitamin D (ergocalciferol vs. cholecalciferol) are now required before recommending this molecule as a potential supplemental therapeutic approach following nerve injury.

Melatonin ameliorates neural function by promoting endogenous neurogenesis through the MT2 melatonin receptor in ischemic-stroke mice

            (Chern, Liao et al. 2012) Download

Melatonin has many protective effects against ischemic stroke, but the underlying neuroprotective mechanisms are not fully understood. Our aim was to explore the relationship between melatonin's neuroprotective effects and activation of the MT2 melatonin receptor in a murine ischemic-stroke model. Male ICR mice were subjected to a transient middle cerebral ischemic/reperfusional injury, and melatonin (5 and 10 mg/kg, ip) was administrated once daily starting 2 h after ischemia. More than 80% of the mice died within 5 days after stroke without treatment. Melatonin treatment significantly improved the survival rates and neural functioning with modestly prolonged life span of the stroke mice by preserving blood-brain barrier (BBB) integrity via a reduction in the enormous amount of stroke-induced free radical production and significant gp91(phox) cell infiltration. These protective effects of melatonin were reversed by pretreatment with MT2 melatonin receptor antagonists (4-phenyl-2-propionamidotetralin (4P-PDOT) and luzindole). Moreover, treatment with melatonin after stroke dramatically enhanced endogenous neurogenesis (doublecortin positive) and cell proliferation (ki67 positive) in the peri-infarct regions. Most ki67-positive cells were nestin-positive and NG2-positive neural stem/progenitor cells that coexpressed two neurodevelopmental proteins (adam11 and adamts20) and the MT2 melatonin receptor. RT-PCR revealed that the gene expression levels of doublecortin, ki67, adamts20, and adam11 are markedly reduced by stroke, but are restored by melatonin treatment; furthermore, pretreatment with 4P-PDOT and luzindole antagonized melatonin's restorative effect. Our results support the hypothesis that melatonin is able to protect mice against stroke by activating MT2 melatonin receptors, which reduces oxidative/inflammatory stress. This results in the preservation of BBB integrity and enhances endogenous neurogenesis by upregulating neurodevelopmental gene/protein expression.


Effect of mannitol on cerebral blood volume in patients with head injury

            (Diringer, Scalfani et al. 2012) Download

BACKGROUND: Mannitol has traditionally been the mainstay of medical therapy for intracranial hypertension in patients with head injury. We previously demonstrated that mannitol reduces brain volume in patients with cerebral edema, although whether this occurs because of a reduction in brain water, blood volume, or both remains poorly understood. OBJECTIVE: To test the hypothesis that mannitol acts by lowering blood viscosity leading to reflex vasoconstriction and a fall in cerebral blood volume (CBV). METHODS: We used O positron emission tomography to study 6 patients with traumatic brain injuries requiring treatment for intracranial hypertension. Cerebral blood flow (CBF), CBV, and cerebral metabolic rate for oxygen (CMRO2) were measured before and 1 hour after administration of 1.0 g/kg 20% mannitol. RESULTS: CBV rose from 4.1 +/- 0.4 to 4.2 +/- 0.2 mL/100 g (P = .3), while intracranial pressure fell from 21.5 +/- 4.9 to 13.7 +/- 5.1 mm Hg (P < .003) after mannitol. Blood pressure, PaCO2, oxygen content, CBF, and CMRO2 did not change. CONCLUSION: A single bolus of 1 g/kg of 20% mannitol does not acutely lower CBV. Another mechanism, such as a reduction in brain water, may better explain mannitol's ability to lower intracranial pressure and reduce mass effect.

Melatonin promotes proliferation and differentiation of neural stem cells subjected to hypoxia in vitro.

            (Fu, Zhao et al. 2011) Download

Melatonin, an endogenously produced neurohormone secreted by the pineal gland, has a variety of physiological functions and neuroprotective effects. It can modulate the functions of neural stem cells (NSCs) including proliferation and differentiation in embryonic brain tissue but its effect and mechanism on the stem cells in hypoxia remains to be explored. Here, we show that melatonin stimulates proliferation of NSCs during hypoxia. Additionally, it also promoted the differentiation of NSCs into neurons. However, it did not appear to exert an obvious effect on the differentiation of astrocytes. The present results have further shown that the promotional effect of NSCs proliferation by melatonin involved the MT1 receptor and increased phosphorylation of ERK1/2. The effect of melatonin on differentiation of NSCs is linked to altered expression of differentiation-related genes. In the light of these findings, it is suggested that melatonin may be beneficial as a supplement for treatment of neonatal hypoxic-ischemic brain injury for promoting the proliferation and differentiation of NSCs.


Sensory neuroprotection, mitochondrial preservation, and therapeutic potential of N-acetyl-cysteine after nerve injury

            (Hart, Terenghi et al. 2004) Download

Neuronal death is a major factor in many neuropathologies, particularly traumatic, and yet no neuroprotective therapies are currently available clinically, although antioxidants and mitochondrial protection appear to be fruitful avenues of research. The simplest system involving neuronal death is that of the dorsal root ganglion after peripheral nerve trauma, where the loss of approximately 40% of primary sensory neurons is a major factor in the overwhelmingly poor clinical outcome of the several million nerve injuries that occur each year worldwide. N-acetyl-cysteine (NAC) is a glutathione substrate which is neuroprotective in a variety of in vitro models of neuronal death, and which may enhance mitochondrial protection. Using TdT uptake nick-end labelling (TUNEL), optical disection, and morphological studies, the effect of systemic NAC treatment upon L4 and 5 primary sensory neuronal death after sciatic nerve transection was investigated. NAC (150 mg/kg/day) almost totally eliminated the extensive neuronal loss found in controls both 2 weeks (no treatment 21% loss, NAC 3%, P=0.03) and 2 months after axotomy (no treatment 35% loss, NAC 3%, P=0.002). Glial cell death was reduced (mean number TUNEL positive cells 2 months after axotomy: no treatment 51/ganglion pair, NAC 16/ganglion pair), and mitochondrial architecture was preserved. The effects were less profound when a lower dose was examined (30 mg/kg/day), although significant neuroprotection still occurred. This provides evidence of the importance of mitochondrial dysregulation in axotomy-induced neuronal death in the peripheral nervous system, and suggests that NAC merits investigation in CNS trauma. NAC is already in widespread clinical use for applications outside the nervous system; it therefore has immediate clinical potential in the prevention of primary sensory neuronal death, and has therapeutic potential in other neuropathological systems.

Effect of growth hormone replacement therapy on cognition after traumatic brain injury

            (High, Briones-Galang et al. 2010) Download

Traumatic brain injury (TBI) is a major public health issue, and yet medical science has little to offer for the persistent symptoms that prevent many of these individuals from fully re-entering society. Post-traumatic hypopituitarism, and specifically growth hormone deficiency (GHD), has been found in a large percentage of individuals with chronic moderate to severe TBI. Presently, there are no published treatment studies of hormone replacement in this population. In this study, 83 subjects with chronic TBI were screened for hypopituitarism. Forty-two subjects were found to have either GHD or GH insufficiency (GHI), of which 23 agreed to be randomized to either a year of GH replacement or placebo. All subjects completed the study with no untoward side effects from treatment. A battery of neuropsychological tests and functional measures were administered before and after treatment. Improvement was seen on the following tests: Dominant Hand Finger Tapping Test, Wechsler Adult Intelligence Scale III-Information Processing Speed Index, California Verbal Learning Test II, and the Wisconsin Card Sorting Test (executive functioning). The findings of this pilot study provide preliminary evidence suggesting that some of the cognitive impairments observed in persons who are GHD/GHI after TBI may be partially reversible with appropriate GH replacement therapy.

Challenging the gold standard: should mannitol remain our first-line defense against intracranial hypertension?

            (Infanti 2008) Download

Mannitol has long been the "gold standard" for treatment of cerebral edema and refractory intracranial hypertension in traumatic brain injury, subarachnoid hemorrhage, and stroke. Studies performed in animals have shown that hypertonic saline (HS), in doses ranging from 3% to 10%, may be more effective than mannitol in treating these populations. Recently, randomized clinical trials have evaluated the efficacy and safety of HS versus mannitol in the treatment of elevated intracranial pressure (ICP). This research has been prompted by mounting concern about the side effects of mannitol, the limited ability to give multiple doses of the drug, and an increased understanding of cerebral physiology. Four studies have compared the use of HS and mannitol in brain-injured populations. These studies have shown that not only is HS a safe drug (no patients experienced adverse effects), it is also more efficient in reducing ICP. Efficiency is defined as the drug's ability to decrease ICP to acceptable levels and to maintain lower ICPs for a longer duration of time. It is important for nurses who administer osmotic diuretics to evaluate and understand the current research to provide educated and appropriate care.

Folic acid supplementation enhances repair of the adult central nervous system

            (Iskandar, Nelson et al. 2004) Download

Folic acid supplementation has proved to be extremely effective in reducing the occurrence of neural tube defects (NTDs) and other congenital abnormalities in humans, suggesting that folic acid can modulate key mechanisms for growth and differentiation in the central nervous system (CNS). To prevent NTDs, however, supplemental folate must be provided early in gestation. This suggests that the ability of folic acid to activate growth and differentiation mechanisms may be confined to the early embryonic period. Here, we show that folic acid can enhance growth and repair mechanisms even in the adult CNS. Using lesion models of CNS injury, we found that intraperitoneal treatment of adult rats with folic acid significantly improves the regrowth of sensory spinal axons into a grafted segment of peripheral nerve in vivo. Regrowth of retinal ganglion cell (RGC) axons into a similar graft also was enhanced, although to a smaller extent than spinal axons. Furthermore, folic acid supplementation enhances neurological recovery from a spinal cord contusion injury, showing its potential clinical impact. The results show that the effects of folic acid supplementation on CNS growth processes are not restricted to the embryonic period, but can also be effective for enhancing growth, repair, and recovery in the injured adult CNS.

Prognostic factors of severe traumatic brain injury outcome in children aged 2-16 years at a major neurosurgical referral centre

            (Kan, Saffari et al. 2009) Download

BACKGROUND: Traumatic Brain Injury (TBI) in children has been poorly studied, and the literature is limited. We evaluated 146 children with severe TBI (coma score less than 8) in an attempt to establish the prognostic factors of severe TBI in children. METHODS: The severity of TBI was assessed via modified Glasgow Coma Score for those more than 3 years old and via Children Coma Score for those under 3 years old. Clinical presentations, laboratory parameters and features of Computerised Tomography brain scans were analyzed. Outcomes were assessed at 6 months with the Pediatric Cerebral Performance Categories Scale; the outcomes were categorised as good or poor outcomes. Correlations with outcome were evaluated using univariate and multivariate logistic models. RESULTS: A low coma score upon admission was independently associated with poor outcome. The presence of diabetes insipidus within 3 days post-TBI (OR: 1.9), hyperglycaemia (OR: 1.2), prolonged PT ratio (OR: 2.3) and leukocytosis (OR: 1.1) were associated with poorer outcome. CONCLUSION: Knowledge of these prognostic factors helps neurosurgeons and neurocritical care specialists to manage and improve outcome in severe TBI in children.

Natural history of recovery from brain injury after prolonged disorders of consciousness: outcome of patients admitted to inpatient rehabilitation with 1-4 year follow-up

            (Katz, Polyak et al. 2009) Download

The natural history of recovery from brain injury typically consists of a period of impaired consciousness, a subsequent period of confusion and amnesia, followed by a period of post-confusional recovery of function. Patients with more severe injuries may have more prolonged episodes of unconsciousness or minimal consciousness and may not fully evolve through this continuum of recovery. There is limited information on the course of recovery and long-term outcome of patients with prolonged unconsciousness, particularly those with extended periods in the minimally conscious state. Further, patients with impaired consciousness are frequently denied access to hospital-based rehabilitation services because of uncertain prognosis and a perceived lack of benefit from rehabilitative interventions. METHODS: A consecutive series of 36 patients with traumatic (TBI) and non-traumatic brain injury (nonTBI) in a vegetative state (VS) or minimally conscious state (MCS) on admission to a specialized, slow-to-recover brain injury program in an acute rehabilitation hospital was retrospectively reviewed to evaluate course of recovery during rehabilitation hospitalization and in follow-up, 1-4 years post-injury. Independent variables included: time to resolution of VS, MCS and confusional state/posttraumatic amnesia (CS/PTA), based on Aspen criteria, Coma Recovery Scale-Revised (CRS-R) and Galveston Orientation and Amnesia Test (GOAT) scores. Outcome measures (calculated separately for TBI, nonTBI, VS, or MCS on admission subgroups) included: proportion of patients who recover and recovery time to MCS, CS/PTA stages, household independence, and return to school or work, as well as Disability Rating Scale (DRS) scores at 1, 2, 3, and 4 years post-injury. RESULTS: The majority emerged from MCS (72%) and CS/PTA (58%) by latest follow-up. It took significantly longer for patients admitted in VS (means: MCS, 16.43 weeks; CS/PTA, 30.1 weeks) than MCS (means: MCS, 7.36 weeks; CS/PTA, 11.5 weeks) to reach both milestones. Almost all who failed to clear CS/PTA by latest follow-up were patients with nonTBI or TBI with VS lasting over 8 weeks. Duration of MCS was a strong predictor of duration CS/PTA after emergence from MCS, accounting for 57% of the variance. Nearly half the patients followed at least 1 year achieved recovery to, at least, daytime independence at home and 22% returned to work or school, 17% at or near pre-injury levels. Discharge FIM score or duration of MCS, along with age, were best predictors of DRS in outcome models. DRS scores continued to improve after 2 and 3 years post-injury. CONCLUSIONS: Patients in VS whose transition to MCS occurred within 8 weeks of onset are likely to continue recovering to higher levels of functioning, a substantial proportion to household independence, and productive pursuits. Patients with TBI are more likely to progress than patients with nonTBI, though significant improvement in the nonTBI group is still possible. Active, higher intensity, rehabilitation should be strongly considered for patients with severely impaired consciousness after brain injury, especially for patients with TBI who have signs of progression to the MCS.

Melatonin and minocycline for combinatorial therapy to improve functional and histopathological deficits following traumatic brain injury

            (Kelso, Scheff et al. 2011) Download

The biochemical sequelae that follow traumatic brain injury (TBI) are numerous and affect many different brain functions at different points of time as the secondary cascades progress. The complexity of the resulting pathophysiology is such that a singular therapeutic intervention may not provide adequate benefit and a combination of drugs targeting different pathways may be needed. Two of the most widely studied injury mechanisms are oxidative stress and inflammation. Numerous studies have suggested that pharmacological agents targeting either of these pathways may produce an improvement in histological and functional outcome measures. We hypothesized that combining melatonin, a potent antioxidant, with minocycline, a bacteriostatic agent that also inhibit microglia, would provide better neuroprotection than either agent used alone. To test this hypothesis, we subjected anesthetized adult male rats to a 1.5mm controlled cortical impact and administered melatonin or vehicle in the acute post-injury period followed by daily minocycline or vehicle injections beginning the following day in a 2x2 study design. The animals were allowed to recover for 5 days before undergoing Morris water maze (MWM) testing to assess cognitive functioning following injury. There was no significant difference in MWM performance between the vehicle, melatonin, minocycline, or combination treatments. Following sacrifice and histological examination for neuroprotection, we did not observe a significant difference between the groups in the amount of cortical tissue that was spared nor was there a significant difference in [(3)H]-PK11195 binding, a marker for activated microglia. These results suggest that neither drug has therapeutic efficacy, however dosing and/or administration issues may have played a role.

Melatonin regulates the calcium-buffering proteins, parvalbumin and hippocalcin, in ischemic brain injury

            (Koh 2012) Download

Melatonin has anti-oxidant activity and it exerts a neuroprotective effects during ischemic brain injury. Calcium-buffering proteins including parvalbumin and hippocalcin are involved in neuronal differentiation and maturation through calcium signaling. This study investigated whether melatonin moderates parvalbumin and hippocalcin expression in cerebral ischemia and glutamate toxicity-induced neuronal cell death. Focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO). Male Sprague-Dawley rats were treated with vehicle or melatonin (5 mg/kg) prior to MCAO, and cerebral cortical tissues were collected 24 hr after MCAO. Parvalbumin and hippocalcin levels were decreased in vehicle-treated animal with MCAO, whereas melatonin prevented the ischemic injury-induced reduction in these proteins. In cultured hippocampal cells, glutamate toxicity decreased parvalbumin and hippocalcin levels, while melatonin treatment prevented the glutamate exposure-induced diminished in these proteins levels. Melatonin also attenuated the glutamate toxicity-induced increase in intracellular Ca(2+) levels. These results suggest that the maintenance of parvalbumin and hippocalcin levels by melatonin in ischemic injury contributes to the neuroprotective effect of melatonin against neuronal cell damage.


Differences in the insulin tolerance test in patients with brain damage depending on posture

            (Kopczak, von Rosen et al. 2011) Download

OBJECTIVE: The insulin tolerance test (ITT) is the gold standard for the diagnosis of GH deficiency (GHD) and hypocortisolism. As hypopituitarism is a common disorder after traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH), the test is increasingly used in patients with pre-existing brain damage. DESIGN: A cross-sectional, observational study. METHODS: Fifty-six patients (41 TBI and 15 SAH) were tested with the ITT (0.15 IE/kg body weight, mean glucose 33 mg/dl). In 38 patients, the test was performed in a supine position; the other 18 patients were in a sitting position during the ITT. RESULTS: Hypocortisolism and GHD were more often diagnosed in a supine than in a sitting position (hypocortisolism: 55.3% supine versus 0% sitting, P<0.0001; GHD: 42.1% supine versus 11.1% sitting, P=0.03). Patients in a sitting position suffered more often from symptoms such as tachycardia (61.1% sitting versus 15.8% supine, P=0.001), trembling (22.2 vs 7.9%, NS), and sweating (66.7 vs 28.9%, P=0.007). There were no significant differences between the groups in drowsiness (72.2% sitting versus 65.8% supine, NS), dizziness (44.4 vs 44.7%, NS), and fatigue (33.3 vs 15.8%, NS). Because of somnolence, the hypoglycemic state could only be stopped with i.v. administration of glucose in 25 supine patients (66%). In contrast, none of the 18 patients (0%) tested in a sitting position got somnolent or was in need of i.v. application of glucose (P<0.001). CONCLUSIONS: In patients with brain injury, posture might affect rates of diagnosing GHD and hypocortisolism and sympathetic symptoms in the ITT. These findings are exploratory and need replication in a standardized setting.

Lasting pituitary hormone deficiency after traumatic brain injury

            (Kozlowski Moreau, Yollin et al. 2012) Download

Pituitary deficiencies have been reported after traumatic brain injury (TBI) and may contribute to lasting cognitive disorders in this context. In a population of TBI patients with persistent cognitive and/or behavioral disorders, we sought to determine the prevalence of lasting pituitary deficiency and relationships with TBI severity, cognitive disorders, and impairments in activities of daily living (ADL). Fifty-five patients were included (mean age 36.1 years; 46 men) at least 1 year after TBI. They underwent a comprehensive evaluation of pituitary function (basic tests and stimulation), initial TBI severity, and long-term outcomes (cognitive performance, Glasgow Outcome Scale score, impact on ADL, and quality of life [QoL]). We used chi-squared and Mann-Whitney tests to probe for significant (p</=0.05) relationships between pituitary disorders and other parameters. Thirty-eight (69%) patients had at least one pituitary hormone deficiency. Growth hormone deficiency was more prevalent (severe: 40.0%; partial: 23.6%) than corticotropin (27.3%) or thyrotropin (21.8%) deficiencies. Other deficiencies were rare. Growth hormone deficiency was associated with attention and verbal memory disorders and reduced involvement in ADL. We did not find any relationship between pituitary deficiency and the TBI's initial severity. In a multivariate analysis, the TBI severity was introduced as a first factor, and pituitary deficits as a secondary factor for explaining the late outcome (ADL and QoL). In conclusion, TBI patients with cognitive sequelae must undergo pituitary screening because growth hormone, corticotropin, and thyrotropin deficits are particularly common and can adversely affect ADL and reduce QoL.

Neuronal injury: folate to the rescue?

            (Kronenberg and Endres 2010) Download

Strong epidemiological evidence indicates that derangement of single-carbon metabolism has detrimental effects for proper CNS functioning. Conversely, a role for folate supplementation in the treatment and prevention of neurodegenerative and neuropsychiatric disorders remains to be established. In this issue of the JCI, in an elegant series of experiments in rodents, Iskandar and colleagues demonstrate a crucial role of folate in the regeneration of afferent spinal neurons after injury. Probing sequential steps in folate metabolism, from cellular entry to DNA methylation, the authors show that axonal regeneration relies upon the integrity of DNA methylation pathways. These findings provide the first demonstration of an epigenetic mechanism contributing to neurorepair and suggest that manipulation of the methylation milieu may offer promising new therapeutic avenues to promote regeneration.

Oral administration of mannitol may be an effective treatment for ischemia-reperfusion injury

            (Liu, Sun et al. 2010) Download

Inhalation of hydrogen gas has been proved to be an effective treatment for ischemia-reperfusion injury. There has been considerable evidence of hydrogen's protective effect to diseases related to oxidative injury, such as the ischemia-reperfusion injury of the brain, liver and heart. Our previous studies demonstrated that intraperitoneal injection of hydrogen-rich saline protected hypoxic-ischemic brain injury, myocardial and intestine ischemia-reperfusion injury in rats. Bacteria in the large intestinal can produce endogenous hydrogen, and our preliminary experiments revealed that oral administration of mannitol in humans and animals can significantly increase the level of endogenous hydrogen. Therefore, we speculated that oral administration of mannitol may be effective against ischemia-reperfusion injury, which is a convenient, effective and unique treatment for ischemia-reperfusion injury.


Ubiquitin C-terminal hydrolase-L1 as a biomarker for ischemic and traumatic brain injury in rats

            (Liu, Akinyi et al. 2010) Download

Ubiquitin C-terminal hydrolase-L1 (UCH-L1), also called neuronal-specific protein gene product 9.5, is a highly abundant protein in the neuronal cell body and has been identified as a possible biomarker on the basis of a recent proteomic study. In this study, we examined whether UCH-L1 was significantly elevated in cerebrospinal fluid (CSF) following controlled cortical impact (CCI) and middle cerebral artery occlusion (MCAO; model of ischemic stroke) in rats. Quantitative immunoblots of rat CSF revealed a dramatic elevation of UCH-L1 protein 48 h after severe CCI and as early as 6 h after mild (30 min) and severe (2 h) MCAO. A sandwich enzyme-linked immunosorbent assay constructed to measure UCH-L1 sensitively and quantitatively showed that CSF UCH-L1 levels were significantly elevated as early as 2 h and up to 48 h after CCI. Similarly, UCH-L1 levels were also significantly elevated in CSF from 6 to 72 h after 30 min of MCAO and from 6 to 120 h after 2 h of MCAO. These data are comparable to the profile of the calpain-produced alphaII-spectrin breakdown product of 145 kDa biomarker. Importantly, serum UCH-L1 biomarker levels were also significantly elevated after CCI. Similarly, serum UCH-L1 levels in the 2-h MCAO group were significantly higher than those in the 30-min group. Taken together, these data from two rat models of acute brain injury strongly suggest that UCH-L1 is a candidate brain injury biomarker detectable in biofluid compartments (CSF and serum).

Head injury (moderate to severe)

            (Maconochie and Ross 2010) Download

INTRODUCTION: Head injury in young adults is often associated with motor vehicle accidents, violence, and sports injuries. In older adults it is often associated with falls. Severe head injury can lead to secondary brain damage from cerebral ischaemia resulting from hypotension, hypercapnia, and raised intracranial pressure. Severity of brain injury is assessed using the Glasgow Coma Scale (GCS). While about one quarter of people with severe brain injury (GCS score less than 8) will make a good recovery, about one third will die, and one fifth will have severe disability or be in a vegetative state. METHODS AND OUTCOMES: We conducted a systematic review and aimed to answer the following clinical question: What are the effects of interventions to reduce complications of moderate to severe head injury as defined by Glasgow Coma Scale? We searched: Medline, Embase, The Cochrane Library, and other important databases up to November 2009 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). RESULTS: We found 17 systematic reviews, RCTs, or observational studies that met our inclusion criteria. CONCLUSIONS: In this systematic review we present information relating to the effectiveness and safety of the following interventions: antibiotics, anticonvulsants, corticosteroids, hyperventilation, hypothermia, and mannitol.

Age-dependent effect of apolipoprotein E4 on functional outcome after controlled cortical impact in mice

            (Mannix, Zhang et al. 2011) Download

The apolipoprotein E4 (APOE4) gene leads to increased brain amyloid beta (Abeta) and poor outcome in adults with traumatic brain injury (TBI); however, its role in childhood TBI is controversial. We hypothesized that the transgenic expression of human APOE4 worsens the outcome after controlled cortical impact (CCI) in adult but not immature mice. Adult and immature APOE4 mice had worse motor outcome after CCI (P<0.001 versus wild type (WT)), but the Morris water maze performance was worse only in adult APOE4 mice (P=0.028 at 2 weeks, P=0.019 at 6 months versus WT), because immature APOE4 mice had performance similar to WT for up to 1 year after injury. Brain lesion size was similar in adult APOE4 mice but was decreased (P=0.029 versus WT) in injured immature APOE4 mice. Microgliosis was similar in all groups. Soluble brain Abeta(40) was increased at 48 hours after CCI in adult and immature APOE4 mice and in adult WT (P<0.05), and was dynamically regulated during the chronic period by APOE4 in adults but not immature mice. The data suggest age-dependent effects of APOE4 on cognitive outcome after TBI, and that therapies targeting APOE4 may be more effective in adults versus children with TBI.

Optimum serum glucose levels for patients with severe traumatic brain injury

            (Marion 2009) Download

Tight glucose control during the acute care of patients with severe traumatic brain injury has recently been advocated based on experimental concerns about deleterious effects of presenting the injured brain with a high glucose load, however, there is little or no clinical evidence that hyperglycemia worsens neurologic injury. The majority of the clinical studies of tight glucose control find that it is associated with an increased risk of hypoglycemic episodes and cellular injury, when compared to conventional glucose control protocols.


Acute management of acquired brain injury part I: an evidence-based review of non-pharmacological interventions

            (Meyer, Megyesi et al. 2010) Download

PRIMARY OBJECTIVE: To review the literature on non-pharmacological interventions used in acute settings to manage elevated intracranial pressure (ICP) and minimize cerebral damage in patients with acquired brain injury (ABI). MAIN OUTCOMES: A literature search of multiple databases (CINAHL, EMBASE, MEDLINE and PSYCHINFO) and hand-searched articles covering the years 1980-2008 was performed. Peer reviewed articles were assessed for methodological quality using the PEDro scoring system for randomized controlled trials (RCTs) and the Downs and Black tool for RCTs and non-randomized trials. Levels of evidence were assigned and recommendations made. RESULTS: Five non-invasive interventions for acute ABI management were assessed: adjusting head posture, body rotation (continuous rotational therapy and prone positioning), hyperventilation, hypothermia and hyperbaric oxygen. Two invasive interventions were also reviewed: cerebrospinal fluid (CSF) drainage and decompressive craniectomy (DC). CONCLUSIONS: There is a paucity of information regarding non-pharmacological acute management of patients with ABI. Strong levels of evidence were found for only four of the seven interventions (decompressive craniectomy, cerebrospinal fluid drainage, hypothermia and hyperbaric oxygen) and only for specific components of their use. Further research into all interventions is warranted.

Acute management of acquired brain injury part II: an evidence-based review of pharmacological interventions

            (Meyer, Megyesi et al. 2010) Download

PRIMARY OBJECTIVE: To review the research literature on pharmacological interventions used in the acute phase of acquired brain injury (ABI) to manage ICP and improve neural recovery. MAIN OUTCOMES: A literature search of multiple databases (CINAHL, EMBASE, MEDLINE and PSYCHINFO) and hand searched articles covering the years 1980-2008 was performed. Peer reviewed articles were assessed for methodological quality using the PEDro scoring system for randomized controlled trials (RCTs) and the Downs and Black tool for RCTs and non-randomized trials. Levels of evidence were assigned and recommendations were made. RESULTS: In total, 11 pharmacological interventions used in the acute management of ABI were evaluated. These included propofol, barbiturates, opioids, midazolam, mannitol, hypertonic saline, corticosteroids, progesterone, bradykinin antagonists, dimethyl sulphoxide and cannabinoids. Of these interventions, corticosteroids were found to be contraindicated and cannabinoids were reported as ineffective. The other nine interventions demonstrated some benefit for treatment of acute ABI. However, rarely did these benefits result in improved long-term patient outcomes. CONCLUSIONS: Substantial research has been devoted to evaluating the use of pharmacological interventions in the acute management of ABI. However, much of this research has focused on the application of individual interventions in small single-site trials. Future research will need to establish larger patient samples to evaluate the benefits of combined interventions within specific patient populations.

Acute management of acquired brain injury Part III: an evidence-based review of interventions used to promote arousal from coma

            (Meyer, Megyesi et al. 2010) Download

PRIMARY OBJECTIVE: To review the literature regarding techniques used to promote arousal from coma following an acquired brain injury. MAIN OUTCOMES: A literature search of multiple databases (CINAHL, EMBASE, MEDLINE and PsycINFO) and hand searched articles covering the years 1980-2008 was performed. Peer reviewed articles were assessed for methodological quality using the PEDro scoring system for randomized controlled trials and the Downs and Black tool for RCTs and non-randomized trials. Levels of evidence were assigned and recommendations were made. RESULTS: Research into coma arousal has generally focused on the stimulation of neural pathways responsible for arousal. These pathways have been targeted using pharmacological and non-pharmacological techniques. This review reports the evidence surrounding agents targeting dopamine pathways (amantadine, bromocriptine and levodopa), sensory stimulation, music therapy and median nerve electrical stimulation. Each of these interventions has shown some degree of benefit in improving consciousness, but further research is necessary. CONCLUSIONS: Despite numerous studies, strong evidence was only found for one intervention (Amantadine use in children) and this was based on a single study. However, each of the interventions showed promise in some aspect of arousal and warrant further study. More methodologically rigorous study is needed before any definitive conclusions can be drawn.

Clinical utility of serum levels of ubiquitin C-terminal hydrolase as a biomarker for severe traumatic brain injury

            (Mondello, Linnet et al. 2012) Download

BACKGROUND: Brain damage markers released in cerebrospinal fluid (CSF) and blood may provide valuable information about diagnosis and outcome prediction after traumatic brain injury (TBI). OBJECTIVE: To examine the concentrations of ubiquitin C-terminal hydrolase-L1 (UCH-L1), a novel brain injury biomarker, in CSF and serum of severe TBI patients and their association with clinical characteristics and outcome. METHODS: This case-control study enrolled 95 severe TBI subjects (Glasgow Coma Scale [GCS] score, 8). Using sensitive UCH-L1 sandwich ELISA, we studied the temporal profile of CSF and serum UCH-L1 levels over 7 days for severe TBI patients. RESULTS: Comparison of serum and CSF levels of UCH-L1 in TBI patients and control subjects shows a robust and significant elevation of UCH-L1 in the acute phase and over the 7-day study period. Serum and CSF UCH-L1 receiver-operating characteristic curves further confirm strong specificity and selectivity for diagnosing severe TBI vs controls, with area under the curve values in serum and CSF statistically significant at all time points up to 24 hours (P < .001). The first 12-hour levels of both serum and CSF UCH-L1 in patients with GCS score of 3 to 5 were also significantly higher than those with GCS score of 6 to 8. Furthermore, UCH-L1 levels in CSF and serum appear to distinguish severe TBI survivors from nonsurvivors within the study, with nonsurvivors having significantly higher and more persistent levels of serum and CSF UCH-L1. Cumulative serum UCH-L1 levels > 5.22 ng/mL predicted death (odds ratio, 4.8). CONCLUSION: Serum levels of UCH-L1 appear to have potential clinical utility in diagnosing TBI, including correlating to injury severity and survival outcome.

Apolipoprotein E4 as a predictor of outcomes in pediatric mild traumatic brain injury

            (Moran, Taylor et al. 2009) Download

The epsilon4 allele of the apolipoprotein E (APOE) gene has been linked to negative outcomes among adults with traumatic brain injury (TBI) across the spectrum of severity, with preliminary evidence suggesting a similar pattern among children. This study investigated the relationship of the APOE epsilon4 allele to outcomes in children with mild TBI. Participants in this prospective, longitudinal study included 99 children with mild TBI between the ages of 8 and 15 recruited from consecutive admissions to Emergency Departments at two large children's hospitals. Outcomes were assessed acutely in the Emergency Department and at follow-ups at 2 weeks, 3 months, and 12 months post-injury. Among the 99 participants, 28 had at least one epsilon4 allele. Children with and without an epsilon4 allele did not differ demographically. Children with an epsilon4 allele were significantly more likely than those without an epsilon4 allele to have a Glasgow Coma Scale score of less than 15, but the groups did not differ on any other measures of injury severity. Those with an epsilon4 allele exhibited better performance than children without an epsilon4 allele on a test of constructional skill, but the groups did not differ on any other neuropsychological tests. Children with and without an epsilon4 allele also did not differ on measures of post-concussive symptoms. Overall, the findings suggest that the APOE epsilon4 allele is not consistently related to the outcomes of mild TBI in children.


The role of bioactive compounds on the promotion of neurite outgrowth

            (More, Koppula et al. 2012) Download

Neurite loss is one of the cardinal features of neuronal injury. Apart from neuroprotection, reorganization of the lost neuronal network in the injured brain is necessary for the restoration of normal physiological functions. Neuritogenic activity of endogenous molecules in the brain such as nerve growth factor is well documented and supported by scientific studies which show innumerable compounds having neurite outgrowth activity from natural sources. Since the damaged brain lacks the reconstructive capacity, more efforts in research are focused on the identification of compounds that promote the reformation of neuronal networks. An abundancy of natural resources along with the corresponding activity profiles have shown promising results in the field of neuroscience. Recently, importance has also been placed on understanding neurite formation by natural products in relation to neuronal injury. Arrays of natural herbal products having plentiful active constituents have been found to enhance neurite outgrowth. They act synergistically with neurotrophic factors to promote neuritogenesis in the diseased brain. Therefore use of natural products for neuroregeneration provides new insights in drug development for treating neuronal injury. In this study, various compounds from natural sources with potential neurite outgrowth activity are reviewed in experimental models.

Methylcobalamin increases Erk1/2 and Akt activities through the methylation cycle and promotes nerve regeneration in a rat sciatic nerve injury model

            (Okada, Tanaka et al. 2010) Download

Methylcobalamin is a vitamin B12 analog and is necessary for the maintenance of the nervous system. Although some previous studies have referred to the effects of methylcobalamin on neurons, the precise mechanism of this effect remains obscure. Here we show that methylcobalamin at concentrations above 100 nM promotes neurite outgrowth and neuronal survival and that these effects are mediated by the methylation cycle, a metabolic pathway involving methylation reactions. We also demonstrate that methylcobalamin increases Erk1/2 and Akt activities through the methylation cycle. In a rat sciatic nerve injury model, continuous administration of high doses of methylcobalamin improves nerve regeneration and functional recovery. Therefore, methylcobalamin may provide the basis for better treatments of nervous disorders through effective systemic or local delivery of high doses of methylcobalamin to target organs.


Growth hormone and prolactin regulate human neural stem cell regenerative activity

            (Pathipati, Gorba et al. 2011) Download

We have previously shown that the growth hormone (GH)/prolactin (PRL) axis has a significant role in regulating neuroprotective and/or neurorestorative mechanisms in the brain and that these effects are mediated, at least partly, via actions on neural stem cells (NSCs). Here, using NSCs with properties of neurogenic radial glia derived from fetal human forebrains, we show that exogenously applied GH and PRL promote the proliferation of NSCs in the absence of epidermal growth factor or basic fibroblast growth factor. When applied to differentiating NSCs, they both induce neuronal progenitor proliferation, but only PRL has proliferative effects on glial progenitors. Both GH and PRL also promote NSC migration, particularly at higher concentrations. Since human GH activates both GH and PRL receptors, we hypothesized that at least some of these effects may be mediated via the latter. Migration studies using receptor-specific antagonists confirmed that GH signals via the PRL receptor promote migration. Mechanisms of receptor signaling in NSC proliferation, however, remain to be elucidated. In summary, GH and PRL have complex stimulatory and modulatory effects on NSC activity and as such may have a role in injury-related recovery processes in the brain.

Fatigue and sleep disturbance following traumatic brain injury--their nature, causes, and potential treatments

            (Ponsford, Ziino et al. 2012) Download

BACKGROUND: Although fatigue and sleep disturbance are commonly reported following traumatic brain injury (TBI), understanding of their nature and treatment remains limited. OBJECTIVES: This article reviews a series of investigations of the nature and causes of fatigue and sleep disturbance following TBI. METHODS: A large cohort of community-based patients with TBI, recruited from a TBI rehabilitation program, completed measures of subjective fatigue and sleep disturbances, as well as attentional measures. A subgroup of participants completed polysomnography and assessment of dim light melatonin onset. RESULTS: Fatigue and sleep disturbance are common. Both are associated with anxiety, depression, and pain. However, fatigue is also associated with slowed information processing and the need for increased effort in performing tasks. Sleep disturbances contribute to fatigue. Objective sleep studies show reduced sleep efficiency, increased sleep onset latency, and increased time awake after sleep onset. Depression and pain exacerbate but cannot entirely account for these problems. There is increased slow-wave sleep. Individuals with TBI show lower levels of evening melatonin production, associated with less rapid-eye movement sleep. CONCLUSIONS: These findings suggest potential treatments including cognitive behavior therapy supporting lifestyle modifications, pharmacologic treatments with modafinil and melatonin, and light therapy to enhance alertness, vigilance, and mood. Controlled trials of these interventions are needed.

Adrenal insufficiency following traumatic brain injury in adults

            (Powner and Boccalandro 2008) Download

PURPOSE OF REVIEW: Hypoadrenalism occurs in approximately 25% of patients soon after traumatic brain injury. Neurosurgeons or critical care physicians should be prepared to diagnose and treat this and other related hormonal deficiencies. RECENT FINDINGS: The severity of traumatic brain injury, location of basilar skull fractures and edema or hemorrhage within the hypothalamic-pituitary axis appear correlated with secondary adrenal failure. Primary hypoadrenalism also may occur due to injury-related systemic inflammation. Hypotension requiring vasoactive drug support, hyponatremia and hypoglycemia may be corresponding clinical signs. Evaluation of either primary or secondary hypoadrenalism should include measurement of basal and post-adrenocorticotropin stimulation cortisol blood concentrations. If the basal cortisol is under 15 microg/dl or increases by over 9 microg/dl after stimulation treatment should be considered. Intravenous hydrocortisone at 50-100 mg every 8 h or by continuous infusion is usually sufficient but may be supplemented with a mineralocorticoid if hyponatremia persists. All patients sustaining severe traumatic brain injury should be tested for endocrine failure (adrenal, thyroid and growth hormone) 3 months after injury. SUMMARY: Adrenal gland failure or the inability to produce adrenocorticotropin and other pituitary hormones may occur early after traumatic brain injury. Acute treatment of either cause of hypoadrenalism may correct associated hypotension, hypoglycemia, or hyponatremia.

Hypothalamic-Pituitary Dysfunction Following Traumatic Brain Injury Affects Functional Improvement During Acute Inpatient Rehabilitation

            (Rosario, Aqeel et al. 2012) Download

OBJECTIVE:: To evaluate the occurrence of hypothalamic-pituitary dysfunction following a traumatic brain injury (TBI) and to determine its effect on functional improvement in acute inpatient rehabilitation. METHODS:: A retrospective chart review identified male patients with a primary diagnosis of TBI with or without a skull fracture, an onset date within 6 months prior to admission, and were 16 years of age or older. The percentage of individuals in this population with abnormal hormone levels was determined on the basis of the established normal reference range for each hormone assay. The functional independence measure, which assesses functional outcomes in acute inpatient rehabilitation, was used to examine the relationship between hormone levels and functional improvement. RESULTS:: Hypothalamic-pituitary dysfunction was identified in nearly 70% of men following TBI. Hypogonadism, or low testosterone levels, was observed in 66% of the patients, followed by low levels of free T4 in 46% and low levels of insulin growth factor-1 in 26% of patients. Hypopituitarism associated with impaired functional recovery. Specifically, the functional independence measure change per day was significantly lower in patients with low levels of testosterone and insulin growth factor-1. CONCLUSIONS:: These findings suggest the importance of testosterone and insulin growth factor-1 activity in the early stages of physical and cognitive rehabilitation.

Endocrine changes after pediatric traumatic brain injury

            (Rose and Auble 2011) Download

Traumatic brain injury (TBI) is a very common occurrence in childhood, and can lead to devastating long term consequences. Recent research has focused on the potential endocrine consequences of TBI in adults. The research in children is less robust. This paper reviews current literature regarding TBI and possible hypothalamic and pituitary deficiencies in childhood. Acute endocrine changes are commonly found after TBI in pediatric patients, which can include changes in hypothalamic-pituitary-adrenal axis and antidiuretic hormone production and release. In the long term, both temporary and permanent alterations in pituitary function have been found. About 30% of children have hypopituitarism up to 5 years after injury. Growth hormone deficiency and disturbances in puberty are the most common, but children can also experience ACTH deficiency, diabetes insipidus, central hypothyroidism, and elevated prolactin. Every hormonal axis can be affected after TBI in children, although growth hormone deficiency and alterations in puberty are the most common. Because transient and permanent hypopituitarism is common after TBI, survivors should be screened serially for possible endocrine disturbances. These children should undergo routine surveillance at least 1 year after injury to ensure early detection of deficiencies in hormonal production in order to permit normal growth and development.

Sleep disturbance and melatonin levels following traumatic brain injury

            (Shekleton, Parcell et al. 2010) Download

OBJECTIVES: Sleep disturbances commonly follow traumatic brain injury (TBI) and contribute to ongoing disability. However, there are no conclusive findings regarding specific changes to sleep quality and sleep architecture measured using polysomnography. Possible causes of the sleep disturbances include disruption of circadian regulation of sleep-wakefulness, psychological distress, and a neuronal response to injury. We investigated sleep-wake disturbances and their underlying mechanisms in a TBI patient sample. METHODS: This was an observational study comparing 23 patients with TBI (429.7 +/- 287.6 days post injury) and 23 age- and gender-matched healthy volunteers on polysomnographic sleep measures, salivary dim light melatonin onset (DLMO) time, and self-reported sleep quality, anxiety, and depression. RESULTS: Patients with TBI reported higher anxiety and depressive symptoms and sleep disturbance than controls. Patients with TBI showed decreased sleep efficiency (SE) and increased wake after sleep onset (WASO). Although no significant group differences were found in sleep architecture, when anxiety and depression scores were controlled, patients with TBI showed higher amount of slow wave sleep. No differences in self-reported sleep timing or salivary DLMO time were found. However, patients with TBI showed significantly lower levels of evening melatonin production. Melatonin level was significantly correlated with REM sleep but not SE or WASO. CONCLUSIONS: Reduced evening melatonin production may indicate disruption to circadian regulation of melatonin synthesis. The results suggest that there are at least 2 factors contributing to sleep disturbances in patients with traumatic brain injury. We propose that elevated depression is associated with reduced sleep quality, and increased slow wave sleep is attributed to the effects of mechanical brain damage.

Progesterone exerts neuroprotective effects after brain injury.

            (Stein 2008) Download

Progesterone, although still widely considered primarily a sex hormone, is an important agent affecting many central nervous system functions. This review assesses recent, primarily in vivo, evidence that progesterone can play an important role in promoting and enhancing repair after traumatic brain injury and stroke. Although many of its specific actions on neuroplasticity remain to be discovered, there is growing evidence that this hormone may be a safe and effective treatment for traumatic brain injury and other neural disorders in humans.

Hypopituitarism due to sports related head trauma and the effects of growth hormone replacement in retired amateur boxers

            (Tanriverdi, Unluhizarci et al. 2010) Download

Traumatic brain injury (TBI) has been recently recognized as a leading cause of pituitary dysfunction. Current data clearly demonstrated that sports related head trauma due to boxing, kickboxing, and soccer might results in pituitary hormone deficiencies, isolated growth hormone (GH) deficiency in particular. In the present report physiologic dose GH replacement therapy (GHRT) was performed in two GH deficient retired amateur boxers for the first time. The boxers received recombinant GH for 6 months. After 6 months of GHRT there were substantial improvements, but not complete normalization, in the body composition parameters, lipid profiles and quality of life scores in both boxers. These preliminary results suggest that GHRT may have beneficial effects in retired boxers with severe isolated GH deficiency due to sports related head trauma. But more data with higher number of boxers and longer GHRT duration are warranted.

The nerve injury and the dying neurons: diagnosis and prevention

            (Terenghi, Hart et al. 2011) Download

Following distal nerve injury significant sensory neuronal cell death occurs in the dorsal root ganglia, while after a more proximal injury, such as brachial plexus injury, a sizeable proportion of spinal motoneurons also undergo cell death. This phenomenon has been undervalued for a long time, but it has a significant role in the lack of functional recuperation, as neuronal cells cannot divide and be replaced, hence the resulting nerve regeneration is usually suboptimal. It is now accepted that this cell death is due to apoptosis, as indicated by analysis of specific genes involved in the apoptotic signalling cascade. Immediate nerve repair, either by direct suturing or nerve grafting, gives a degree of neuroprotection, but this approach does not fully prevent neuronal cell death and importantly it is not always possible. Our work has shown that pharmacological intervention using either acetyl-L-carnitine (ALCAR) or N-acetyl-cysteine (NAC) give complete neuroprotection in different types of peripheral nerve injury. Both compounds are clinically safe and experimental work has defined the best dose, timing after injury and duration of administration. The efficacy of neuroprotection of ALCAR and NAC can be monitored non-invasively using MRI, as demonstrated experimentally and more recently by clinical studies of the volume of dorsal root ganglia. Translation to patients of this pharmacological intervention requires further work, but the available results indicate that this approach will help to secure a better functional outcome following peripheral nerve injury and repair.

7Alpha-hydroxypregnenolone mediates melatonin action underlying diurnal locomotor rhythms

            (Tsutsui, Inoue et al. 2008) Download

Melatonin regulates diurnal changes in locomotor activity in vertebrates, but the molecular mechanism for this neurohormonal regulation of behavior is poorly understood. Here we show that 7alpha-hydroxypregnenolone, a previously undescribed avian neurosteroid, mediates melatonin action on diurnal locomotor rhythms in quail. In this study, we first identified 7alpha-hydroxypregnenolone and its stereoisomer 7beta-hydroxypregnenolone in quail brain. These neurosteroids have not been described previously in avian brain. We then demonstrated that 7alpha-hydroxypregnenolone acutely increased quail locomotor activity. To analyze the production of 7alpha-hydroxypregnenolone, cytochrome P450(7alpha), a steroidogenic enzyme of this neurosteroid, was also identified. Subsequently, we demonstrated diurnal changes in 7alpha-hydroxypregnenolone synthesis in quail. 7Alpha-Hydroxypregnenolone synthesis and locomotor activity in males were much higher than in females. This is the first demonstration in any vertebrate of a clear sex difference in neurosteroid synthesis. This sex difference in 7alpha-hydroxypregnenolone synthesis corresponded to the sex difference in locomotion. We show that only males exhibited marked diurnal changes in 7alpha-hydroxypregnenolone synthesis, and these changes occurred in parallel with changes in locomotor activity. Finally, we identified melatonin as a key component of the mechanism regulating 7alpha-hydroxypregnenolone synthesis. Increased synthesis of 7alpha-hydroxypregnenolone occurred in males in vivo after melatonin removal via pinealectomy and orbital enucleation (Px plus Ex). Conversely, decreased synthesis of this neurosteroid occurred after melatonin administration to Px plus Ex males. This study demonstrates that melatonin regulates synthesis of 7alpha-hydroxypregnenolone, a key factor for induction of locomotor activity, thus inducing diurnal locomotor changes in male birds. This is a previously undescribed role for melatonin.

7alpha-hydroxypregnenolone, a new key regulator of locomotor activity of vertebrates: identification, mode of action, and functional significance

            (Tsutsui, Haraguchi et al. 2010) Download

Steroids synthesized de novo by the central and peripheral nervous systems are called neurosteroids. The formation of neurosteroids from cholesterol in the brain was originally demonstrated in mammals by Baulieu and colleagues. Our studies over the past two decades have also shown that, in birds and amphibians as in mammals, the brain expresses several kinds of steroidogenic enzymes and produces a variety of neurosteroids. Thus, de novo neurosteroidogenesis from cholesterol is a conserved property that occurs throughout vertebrates. However, the biosynthetic pathways of neurosteroids in the brain of vertebrates was considered to be still incompletely elucidated. Recently, 7alpha-hydroxypregnenolone was identified as a novel bioactive neurosteroid stimulating locomotor activity in the brain of newts and quail through activation of the dopaminergic system. Subsequently, diurnal and seasonal changes in synthesis of 7alpha-hydroxypregnenolone in the brain were demonstrated. Interestingly, melatonin derived from the pineal gland and eyes regulates 7alpha-hydroxypregnenolone synthesis in the brain, thus inducing diurnal locomotor changes. Prolactin, an adenohypophyseal hormone, regulates 7alpha-hydroxypregnenolone synthesis in the brain, and may also induce seasonal locomotor changes. This review highlights the identification, mode of action, and functional significance of 7alpha-hydroxypregnenolone, a new key regulator of locomotor activity of vertebrates, in terms of diurnal and seasonal changes in 7alpha-hydroxypregnenolone synthesis, and describes some of their regulatory mechanisms.

Screening of natural medicines that efficiently activate neurite outgrowth in PC12 cells in C2C12-cultured medium

            (Uezato, Sato et al. 2012) Download

We have studied the effects of natural medicines on neurite outgrowth in PC12D cells in a cultured medium of C2C12 cells. Derived from mouse myoblasts, the C2C12 cells secrete neurotrophic factors including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3). The secretion of these neurotrophins from C2C12 cells stimulate neurite outgrowth in PC12D cells. We have screened a total of 120 samples and found five natural medicines: Trichosanthes Root, Asiasarum Root, Lycium Bark, Sinomenium Stem, and Dictamni radicis Cortex, that enhance the activity of C2C12-cultured medium to stimulate neurite outgrowth in PC12D cells. These natural medicines promoted not only neurite outgrowth but also stabilized the neurite formation in PC12D cells for several days. RT-PCR analysis showed that NGF was significantly increased with Trichosanthes and Lycium Bark. However, BDNF was slightly decreased with Lycium Bark, Sinomenium Stem, and Dictamni radicis Cortex. NT-3 was increased slightly by all of these natural medicines except Sinomenium Stem. All these five natural medicines significantly increased the number and length of neurites in PC12D cells in co-culture with C2C12 cells.

Progesterone and its metabolite allopregnanolone differentially regulate hemostatic proteins after traumatic brain injury

            (VanLandingham, Cekic et al. 2008) Download

Our laboratory has shown in numerous experiments that the neurosteroids progesterone (PROG) and allopregnanolone (ALLO) improve molecular and functional outcomes after traumatic brain injury (TBI). As coagulopathy is an important contributor to the secondary destruction of nervous tissue, we hypothesized that PROG and ALLO administration may also have a beneficial effect on coagulation protein expression after TBI. Adult male Sprague-Dawley rats were given bilateral contusions of the medial frontal cortex followed by treatments with PROG (16 mg/kg), ALLO (8 mg/kg), or vehicle (22.5% hydroxypropyl-beta-cyclodextrin). Controls received no injury or injections. Progesterone generally maintained procoagulant (thrombin, fibrinogen, and coagulation factor XIII), whereas ALLO increased anticoagulant protein expression (tissue-type plasminogen activator, tPA). In addition, PROG significantly increased the ratio of tPA bound to neuroserpin, a serine protease inhibitor that can reduce the activity of tPA. Our findings suggest that in a model of TBI, where blood loss may exacerbate injury, it may be preferable to treat patients with PROG, whereas it might be more appropriate to use ALLO as a treatment for thrombotic stroke, where a reduction in coagulation would be more beneficial.

Growth hormone (GH), brain development and neural stem cells

            (Waters and Blackmore 2011) Download

A range of observations support a role for GH in development and function of the brain. These include altered brain structure in GH receptor null mice, and impaired cognition in GH deficient rodents and in a subgroup of GH receptor defective patients (Laron dwarfs). GH has been shown to alter neurogenesis, myelin synthesis and dendritic branching, and both the GH receptor and GH itself are expressed widely in the brain. We have found a population of neural stem cells which are activated by GH infusion, and which give rise to neurons in mice. These stem cells are activated by voluntary exercise in a GH-dependent manner. Given the findings that local synthesis of GH occurs in the hippocampus in response to a memory task, and that GH replacement improves memory and cognition in rodents and humans, these new observations warrant a reappraisal of the clinical importance of GH replacement in GH deficient states.

Effects of N-acetyl-cysteine on the survival and regeneration of sural sensory neurons in adult rats

            (Welin, Novikova et al. 2009) Download

Microsurgical reconstruction of injured peripheral nerves often results in limited functional recovery. One contributing factor is the retrograde neuronal degeneration of sensory neurons in the dorsal root ganglia (DRG) and of motor neurons in the spinal cord. The present study investigates the neuroprotective and growth-promoting effects of N-acetyl-cysteine (NAC) on sensory DRG neurons and spinal motoneurons after sciatic axotomy and nerve grafting in adult rats. Sciatic axotomy and nerve grafting were performed at 1 week after sural DRG neurons and motoneurons were retrogradely labeled with the fluorescent tracer Fast Blue. To assess the efficacy of axonal regeneration, a second fluorescent dye Fluoro-Ruby was applied distal to the graft at 12 weeks after nerve repair. At 8-13 weeks after axotomy, only 52-56% of the sural sensory neurons remained in the lumbar DRG, while the majority of motoneurons survived the sciatic nerve injury. Nerve grafting alone or continuous intrathecal NAC treatment (2.4 mg/day) improved survival of sural DRG neurons. Combined treatment with nerve graft and NAC had significant additive effect on neuronal survival and also increased the number of sensory neurons regenerating across the graft. However, NAC treatment neither affected the number of regenerating motoneurons nor the number of myelinated axons in the nerve graft or in the distal nerve stump. The present results demonstrate that NAC provides a highly significant effect of neuroprotection in an animal nerve injury model and that combination with nerve grafting further attenuates retrograde cell death and promotes regeneration of sensory neurons.

High prevalence of chronic pituitary and target-organ hormone abnormalities after blast-related mild traumatic brain injury

            (Wilkinson, Pagulayan et al. 2012) Download

Studies of traumatic brain injury from all causes have found evidence of chronic hypopituitarism, defined by deficient production of one or more pituitary hormones at least 1 year after injury, in 25-50% of cases. Most studies found the occurrence of posttraumatic hypopituitarism (PTHP) to be unrelated to injury severity. Growth hormone deficiency (GHD) and hypogonadism were reported most frequently. Hypopituitarism, and in particular adult GHD, is associated with symptoms that resemble those of PTSD, including fatigue, anxiety, depression, irritability, insomnia, sexual dysfunction, cognitive deficiencies, and decreased quality of life. However, the prevalence of PTHP after blast-related mild TBI (mTBI), an extremely common injury in modern military operations, has not been characterized. We measured concentrations of 12 pituitary and target-organ hormones in two groups of male US Veterans of combat in Iraq or Afghanistan. One group consisted of participants with blast-related mTBI whose last blast exposure was at least 1 year prior to the study. The other consisted of Veterans with similar military deployment histories but without blast exposure. Eleven of 26, or 42% of participants with blast concussions were found to have abnormal hormone levels in one or more pituitary axes, a prevalence similar to that found in other forms of TBI. Five members of the mTBI group were found with markedly low age-adjusted insulin-like growth factor-I (IGF-I) levels indicative of probable GHD, and three had testosterone and gonadotropin concentrations consistent with hypogonadism. If symptoms characteristic of both PTHP and PTSD can be linked to pituitary dysfunction, they may be amenable to treatment with hormone replacement. Routine screening for chronic hypopituitarism after blast concussion shows promise for appropriately directing diagnostic and therapeutic decisions that otherwise may remain unconsidered and for markedly facilitating recovery and rehabilitation.

Acetyl-l-carnitine increases nerve regeneration and target organ reinnervation - a morphological study

            (Wilson, Hart et al. 2010) Download

Peripheral nerve injury frequently results in functional morbidity since standard management fails to adequately address many of the neurobiological hurdles to optimal regeneration. Neuronal survival and regeneration are neurotrophin dependent and require increased aerobic capacity. Acetyl-l-carnitine (ALCAR) facilitates this need and prevents neuronal loss. ALCAR is clinically safe and is shown here to significantly improve nerve regeneration and target organ reinnervation. Two groups of five rats underwent sciatic nerve division followed by immediate repair. One group received parenteral ALCAR (50mg/kg/day) from time of operation until termination at 12 weeks. A 'sham treatment' group received normal saline. A third group was left unoperated and did not receive any treatment. A segment of nerve was harvested between 5mm proximal and 10mm distal to the repair in operated groups, and at the corresponding level in the unoperated group. Mean axonal count in normal, non-axotomised nerve was 14,720 (SD 2378). That of the saline group (17,217 SD 1808) was not significantly different from normal nerve (P=0.0985). Mean number of myelinated axons in the ALCAR group (24,460 SD 3750) was significantly greater than both sham group (P<0.01) and normal nerve (P=0.0012). Mean myelin thickness in the saline treated group (0.408 microm SD 0.067 microm) was less than normal nerve (0.770 microm SD 0.143 microm) (P<0.001). Mean myelin thickness in the ALCAR group (0.627 microm SD 0.052 microm) was greater than the sham (saline) group (P<0.01) and not statistically different from normal nerve (P=0.07). ALCAR increased dermal PGP9.5 staining by 210% compared to sham treatment (P<0.0001) and significantly reduced the mean percentage weight loss in gastrocnemius muscle (ALCAR group 0.203% vs. 0.312% in sham group P=0.015). ALCAR not only increases the number of regenerating nerve fibres but also morphologically improves the quality of regeneration and target organ reinnervation. Adjuvant ALCAR treatment may improve both sensory and motor outcomes and merits further investigation.

Isorhamnetin, A Flavonol Aglycone from Ginkgo biloba L., Induces Neuronal Differentiation of Cultured PC12 Cells: Potentiating the Effect of Nerve Growth Factor

            (Xu, Choi et al. 2012) Download

Flavonoids, a group of compounds mainly derived from vegetables and herbal medicines, share a chemical resemblance to estrogen, and indeed some of which have been used as estrogen substitutes. In searching for possible functions of flavonoids, the neuroprotective effect in brain could lead to novel treatment, or prevention, for neurodegenerative diseases. Here, different subclasses of flavonoids were analyzed for its inductive role in neurite outgrowth of cultured PC12 cells. Amongst the tested flavonoids, a flavonol aglycone, isorhamnetin that was isolated mainly from the leaves of Ginkgo biloba L. showed robust induction in the expression of neurofilament, a protein marker for neurite outgrowth, of cultured PC12 cells. Although isorhamnetin by itself did not show significant inductive effect on neurite outgrowth of cultured PC12 cells, the application of isorhamnetin potentiated the nerve growth factor- (NGF-)induced neurite outgrowth. In parallel, the expression of neurofilaments was markedly increased in the cotreatment of NGF and isorhamnetin in the cultures. The identification of these neurite-promoting flavonoids could be very useful in finding potential drugs, or food supplements, for treating various neurodegenerative diseases, including Alzheimer's disease and depression.

Lithium chloride reinforces the regeneration-promoting effect of chondroitinase ABC on rubrospinal neurons after spinal cord injury

            (Yick, So et al. 2004) Download

After spinal cord injury, enzymatic digestion of chondroitin sulfate proteoglycans promotes axonal regeneration of central nervous system neurons across the lesion scar. We examined whether chondroitinase ABC (ChABC) promotes the axonal regeneration of rubrospinal tract (RST) neurons following injury to the spinal cord. The effect of a GSK-3beta inhibitor, lithium chloride (LiCl), on the regeneration of axotomized RST neurons was also assessed. Adult rats received a unilateral hemisection at the seventh cervical spinal cord segment (C7). Four weeks after different treatments, regeneration of RST axons across the lesion scar was examined by injection of Fluoro-Gold at spinal segment T2, and locomotor recovery was studied by a test of forelimb usage. Injured RST axons did not regenerate spontaneously after spinal cord injury, and intraperitoneal injection of LiCl alone did not promote the regeneration of RST axons. Administration of ChABC at the lesion site enhanced the regeneration of RST axons by 20%. Combined treatment of LiCl together with ChABC significantly increased the regeneration of RST axons to 42%. Animals receiving combined treatment used both forelimbs together more often than animals that received sham or single treatment. Immunoblotting and immunohistochemical analysis revealed that LiCl induced the expression of inactive GSK-3beta as well as the upregulation of Bcl-2 in injured RST neurons. These results indicate that in vivo, LiCl inhibits GSK-3beta and reinforces the regeneration-promoting function of ChABC through a Bcl-2-dependent mechanism. Combined use of LiCl together with ChABC could be a novel treatment for spinal cord injury.

Meta-analysis of APOE4 allele and outcome after traumatic brain injury

         (Zhou, Xu et al. 2008) Download

There is conflicting evidence regarding a possible association between the apolipoprotein E4 (APOE4) allele and the consequences of traumatic brain injury (TBI). Our aim was to carry out a meta-analysis of cohort studies of sufficient rigor to determine whether the presence of the APOE4 allele contributes to initial injury severity and/or poor outcome following TBI. MEDLINE, EMBase, CBMdisc, and CNKI databases were searched for literature published from January 1993 to October 2007. Of the 100 identified studies, 14 cohort studies were selected for analysis based on comprehensive quality assessment using a standardized scale. Data from the 14 eligible cohort studies included a total of 2527 participants, 736 with and 1791 without the APOE4 allele. The APOE4 allele was not associated with initial injury severity of TBI. The pooled RR were 1.11 (95% confidence interval [CI], 0.91 to 1.35) for severe injury, 1.06 (95% CI, 0.86-1.31) for moderate injury and 0.93 (95% CI, 0.81-1.06) for mild injury. However, the APOE4 allele was significantly associated with a poor outcome of TBI at 6 months after injury (RR = 1.36; 95% CI, 1.04-1.78). The association remained significant in sensitivity tests. This meta-analysis indicates that the presence of the APOE4 allele is not associated with the initial severity of brain injury following TBI but is associated with increased risk of poor long-term outcome at 6 months after injury.


References

Bonnet, E., K. Touyarot, et al. (2008). "Retinoic acid restores adult hippocampal neurogenesis and reverses spatial memory deficit in vitamin A deprived rats." PLoS One 3(10): e3487.

Chabas, J. F., O. Alluin, et al. (2008). "Vitamin D2 potentiates axon regeneration." J Neurotrauma 25(10): 1247-56.

Chern, C. M., J. F. Liao, et al. (2012). "Melatonin ameliorates neural function by promoting endogenous neurogenesis through the MT2 melatonin receptor in ischemic-stroke mice." Free Radic Biol Med 52(9): 1634-47.

Diringer, M. N., M. T. Scalfani, et al. (2012). "Effect of mannitol on cerebral blood volume in patients with head injury." Neurosurgery 70(5): 1215-8; discussion 1219.

Fu, J., S. D. Zhao, et al. (2011). "Melatonin promotes proliferation and differentiation of neural stem cells subjected to hypoxia in vitro." J Pineal Res 51(1): 104-12.

Hart, A. M., G. Terenghi, et al. (2004). "Sensory neuroprotection, mitochondrial preservation, and therapeutic potential of N-acetyl-cysteine after nerve injury." Neuroscience 125(1): 91-101.

High, W. M., Jr., M. Briones-Galang, et al. (2010). "Effect of growth hormone replacement therapy on cognition after traumatic brain injury." J Neurotrauma 27(9): 1565-75.

Infanti, J. L. (2008). "Challenging the gold standard: should mannitol remain our first-line defense against intracranial hypertension?" J Neurosci Nurs 40(6): 362-8.

Iskandar, B. J., A. Nelson, et al. (2004). "Folic acid supplementation enhances repair of the adult central nervous system." Ann Neurol 56(2): 221-7.

Kan, C. H., M. Saffari, et al. (2009). "Prognostic factors of severe traumatic brain injury outcome in children aged 2-16 years at a major neurosurgical referral centre." Malays J Med Sci 16(4): 25-33.

Katz, D. I., M. Polyak, et al. (2009). "Natural history of recovery from brain injury after prolonged disorders of consciousness: outcome of patients admitted to inpatient rehabilitation with 1-4 year follow-up." Prog Brain Res 177: 73-88.

Kelso, M. L., N. N. Scheff, et al. (2011). "Melatonin and minocycline for combinatorial therapy to improve functional and histopathological deficits following traumatic brain injury." Neurosci Lett 488(1): 60-4.

Koh, P. O. (2012). "Melatonin regulates the calcium-buffering proteins, parvalbumin and hippocalcin, in ischemic brain injury." J Pineal Res.

Kopczak, A., F. von Rosen, et al. (2011). "Differences in the insulin tolerance test in patients with brain damage depending on posture." Eur J Endocrinol 164(1): 31-6.

Kozlowski Moreau, O., E. Yollin, et al. (2012). "Lasting pituitary hormone deficiency after traumatic brain injury." J Neurotrauma 29(1): 81-9.

Kronenberg, G. and M. Endres (2010). "Neuronal injury: folate to the rescue?" J Clin Invest 120(5): 1383-6.

Liu, M. C., L. Akinyi, et al. (2010). "Ubiquitin C-terminal hydrolase-L1 as a biomarker for ischemic and traumatic brain injury in rats." Eur J Neurosci 31(4): 722-32.

Liu, S., Q. Sun, et al. (2010). "Oral administration of mannitol may be an effective treatment for ischemia-reperfusion injury." Med Hypotheses 75(6): 620-2.

Maconochie, I. and M. Ross (2010). "Head injury (moderate to severe)." Clin Evid (Online) 2010.

Mannix, R. C., J. Zhang, et al. (2011). "Age-dependent effect of apolipoprotein E4 on functional outcome after controlled cortical impact in mice." J Cereb Blood Flow Metab 31(1): 351-61.

Marion, D. W. (2009). "Optimum serum glucose levels for patients with severe traumatic brain injury." F1000 Med Rep 1.

Meyer, M. J., J. Megyesi, et al. (2010). "Acute management of acquired brain injury part I: an evidence-based review of non-pharmacological interventions." Brain Inj 24(5): 694-705.

Meyer, M. J., J. Megyesi, et al. (2010). "Acute management of acquired brain injury part II: an evidence-based review of pharmacological interventions." Brain Inj 24(5): 706-21.

Meyer, M. J., J. Megyesi, et al. (2010). "Acute management of acquired brain injury Part III: an evidence-based review of interventions used to promote arousal from coma." Brain Inj 24(5): 722-9.

Mondello, S., A. Linnet, et al. (2012). "Clinical utility of serum levels of ubiquitin C-terminal hydrolase as a biomarker for severe traumatic brain injury." Neurosurgery 70(3): 666-75.

Moran, L. M., H. G. Taylor, et al. (2009). "Apolipoprotein E4 as a predictor of outcomes in pediatric mild traumatic brain injury." J Neurotrauma 26(9): 1489-95.

More, S. V., S. Koppula, et al. (2012). "The role of bioactive compounds on the promotion of neurite outgrowth." Molecules 17(6): 6728-53.

Okada, K., H. Tanaka, et al. (2010). "Methylcobalamin increases Erk1/2 and Akt activities through the methylation cycle and promotes nerve regeneration in a rat sciatic nerve injury model." Exp Neurol 222(2): 191-203.

Pathipati, P., T. Gorba, et al. (2011). "Growth hormone and prolactin regulate human neural stem cell regenerative activity." Neuroscience 190: 409-27.

Ponsford, J. L., C. Ziino, et al. (2012). "Fatigue and sleep disturbance following traumatic brain injury--their nature, causes, and potential treatments." J Head Trauma Rehabil 27(3): 224-33.

Powner, D. J. and C. Boccalandro (2008). "Adrenal insufficiency following traumatic brain injury in adults." Curr Opin Crit Care 14(2): 163-6.

Rosario, E. R., R. Aqeel, et al. (2012). "Hypothalamic-Pituitary Dysfunction Following Traumatic Brain Injury Affects Functional Improvement During Acute Inpatient Rehabilitation." J Head Trauma Rehabil.

Rose, S. R. and B. A. Auble (2011). "Endocrine changes after pediatric traumatic brain injury." Pituitary.

Shekleton, J. A., D. L. Parcell, et al. (2010). "Sleep disturbance and melatonin levels following traumatic brain injury." Neurology 74(21): 1732-8.

Stein, D. G. (2008). "Progesterone exerts neuroprotective effects after brain injury." Brain Res Rev 57(2): 386-97.

Tanriverdi, F., K. Unluhizarci, et al. (2010). "Hypopituitarism due to sports related head trauma and the effects of growth hormone replacement in retired amateur boxers." Pituitary 13(2): 111-4.

Terenghi, G., A. Hart, et al. (2011). "The nerve injury and the dying neurons: diagnosis and prevention." J Hand Surg Eur Vol 36(9): 730-4.

Tsutsui, K., S. Haraguchi, et al. (2010). "7alpha-hydroxypregnenolone, a new key regulator of locomotor activity of vertebrates: identification, mode of action, and functional significance." Front Endocrinol (Lausanne) 1: 9.

Tsutsui, K., K. Inoue, et al. (2008). "7Alpha-hydroxypregnenolone mediates melatonin action underlying diurnal locomotor rhythms." J Neurosci 28(9): 2158-67.

Uezato, T., E. Sato, et al. (2012). "Screening of natural medicines that efficiently activate neurite outgrowth in PC12 cells in C2C12-cultured medium." Biomed Res 33(1): 25-33.

VanLandingham, J. W., M. Cekic, et al. (2008). "Progesterone and its metabolite allopregnanolone differentially regulate hemostatic proteins after traumatic brain injury." J Cereb Blood Flow Metab 28(11): 1786-94.

Waters, M. J. and D. G. Blackmore (2011). "Growth hormone (GH), brain development and neural stem cells." Pediatr Endocrinol Rev 9(2): 549-53.

Welin, D., L. N. Novikova, et al. (2009). "Effects of N-acetyl-cysteine on the survival and regeneration of sural sensory neurons in adult rats." Brain Res 1287: 58-66.

Wilkinson, C. W., K. F. Pagulayan, et al. (2012). "High prevalence of chronic pituitary and target-organ hormone abnormalities after blast-related mild traumatic brain injury." Front Neurol 3: 11.

Wilson, A. D., A. Hart, et al. (2010). "Acetyl-l-carnitine increases nerve regeneration and target organ reinnervation - a morphological study." J Plast Reconstr Aesthet Surg 63(7): 1186-95.

Xu, S. L., R. C. Choi, et al. (2012). "Isorhamnetin, A Flavonol Aglycone from Ginkgo biloba L., Induces Neuronal Differentiation of Cultured PC12 Cells: Potentiating the Effect of Nerve Growth Factor." Evid Based Complement Alternat Med 2012: 278273.

Yick, L. W., K. F. So, et al. (2004). "Lithium chloride reinforces the regeneration-promoting effect of chondroitinase ABC on rubrospinal neurons after spinal cord injury." J Neurotrauma 21(7): 932-43.

Zhou, W., D. Xu, et al. (2008). "Meta-analysis of APOE4 allele and outcome after traumatic brain injury." J Neurotrauma 25(4): 279-90.