Neuroprotection against surgically induced brain injury

Cerebrospinal Fluid from Patients After Craniotomy with the Appearance of Interleukin-6 Storm Can Activate Microglia to Damage the Hypothalamic Neurons in Mice

We monitored CSF (cerebrospinal fluid) for Th1/Th2 inflammatory cytokines in a patient with unexplained postoperative disturbance of consciousness after craniotomy and found that the level of IL-6 (interleukin-6) concentrations was extremely high, meeting the traditional criteria for an inflammatory cytokine storm. Subsequently, the cerebrospinal fluid specimens of several patients were tested, and it was found that IL-6 levels were increased in different degrees after craniotomy. Previous studies have focused more on mild and long-term IL-6 elevation, but less on the effects of this short-term IL-6 inflammatory cytokine storm. Cerebrospinal fluid rich in IL-6 may play a significant role in patients after craniotomy. The objective is to explore the degree of IL-6 elevation and the incidence of IL-6 inflammatory cytokine storm in patients after craniotomy, as well as the effect of IL-6 elevation on the brain. In this study, the levels and clinical manifestations of inflammatory factors in cerebrospinal fluid after craniotomy were statistically classified, and the underlying mechanisms were discussed preliminarily. CSF specimens of patients after craniotomy were collected, IL-6 level was measured at 1, 5, and 10 days after operation, and cognitive function was analyzed at 1, 10, and 180 days after surgery. Craniotomy mouse model, cerebrospinal fluid of patients with the appearance of IL-6 storm after craniotomy, and IL-6 at the same concentration stimulation model were established. Behavioral tests, fluorescence in situ hybridization (FISH), pathological means, western blot, and ELISA (enzyme-linked immune-sorbent assay) were performed for verification. CSF from patients after craniotomy caused disturbance of consciousness in mice, affected neuronal damage in the hypothalamus, activation of microglia in the hypothalamus, and decreased expression of barrier proteins in the hypothalamus and brain. The large amount of interleukin-6 in CSF after craniotomy was found to be mainly derived from astrocytes. The IL-6 level in CSF after craniotomy correlated inversely with patients' performance in MoCA test. High levels of IL-6 in the cerebrospinal fluid derived from astrocytes after craniotomy may lead to disruption of the brain-cerebrospinal fluid barrier, most notably around the hypothalamus, which might result in inflammatory activation of microglia to damage the hypothalamic neurons and impaired cognitive function/more gradual cognitive repairment in patients after craniotomy with the appearance of IL-6 storm.

General Treatments Promoting Independent Living in Parkinson's Patients and Physical Therapy Approaches for Improving Gait-A Comprehensive Review

This study delves into the multifaceted approaches to treating Parkinson's disease (PD), a neurodegenerative disorder primarily affecting motor function but also manifesting in a variety of symptoms that vary greatly among individuals. The complexity of PD symptoms necessitates a comprehensive treatment strategy that integrates surgical interventions, pharmacotherapy, and physical therapy to tailor to the unique needs of each patient. Surgical options, such as deep brain stimulation (DBS), have been pivotal for patients not responding adequately to medication, offering significant symptom relief. Pharmacotherapy remains a cornerstone of PD management, utilizing drugs like levodopa, dopamine agonists, and others to manage symptoms and, in some cases, slow down disease progression. However, these treatments often lead to complications over time, such as motor fluctuations and dyskinesias, highlighting the need for precise dosage adjustments and sometimes combination therapies to optimize patient outcomes. Physical therapy plays a critical role in addressing the motor symptoms of PD, including bradykinesia, muscle rigidity, tremors, postural instability, and akinesia. PT techniques are tailored to improve mobility, balance, strength, and overall quality of life. Strategies such as gait and balance training, strengthening exercises, stretching, and functional training are employed to mitigate symptoms and enhance functional independence. Specialized approaches like proprioceptive neuromuscular facilitation (PNF), the Bobath concept, and the use of assistive devices are also integral to the rehabilitation process, aimed at improving patients' ability to perform daily activities and reducing the risk of falls. Innovations in technology have introduced robotic-assisted gait training (RAGT) and other assistive devices, offering new possibilities for patient care. These tools provide targeted support and feedback, allowing for more intensive and personalized rehabilitation sessions. Despite these advancements, high costs and accessibility issues remain challenges that need addressing. The inclusion of exercise and activity beyond structured PT sessions is encouraged, with evidence suggesting that regular physical activity can have neuroprotective effects, potentially slowing disease progression. Activities such as treadmill walking, cycling, and aquatic exercises not only improve physical symptoms but also contribute to emotional well-being and social interactions. In conclusion, treating PD requires a holistic approach that combines medical, surgical, and therapeutic strategies. While there is no cure, the goal is to maximize patients' functional abilities and quality of life through personalized treatment plans. This integrated approach, along with ongoing research and development of new therapies, offers hope for improving the management of PD and the lives of those affected by this challenging disease.

Intracerebellar injection of monocytic immature myeloid cells prevents the adverse effects caused by stereotactic surgery in a model of cerebellar neurodegeneration

BACKGROUND

Myeloid-derived suppressor cells (MDSCs) constitute a recently discovered bone-marrow-derived cell type useful for dealing with neuroinflammatory disorders. However, these cells are only formed during inflammatory conditions from immature myeloid cells (IMCs) that acquire immunosuppressive activity, thus being commonly gathered from diseased animals. Then, to obtain a more clinically feasible source, we characterized IMCs directly derived from healthy bone marrow and proved their potential immunosuppressive activity under pathological conditions in vitro. We then explored their neuroprotective potential in a model of human cerebellar ataxia, the Purkinje Cell Degeneration (PCD) mouse, as it displays a well-defined neurodegenerative and neuroinflammatory process that can be also aggravated by invasive surgeries.

METHODS

IMCs were obtained from healthy bone marrow and co-cultured with activated T cells. The proliferation and apoptotic rate of the later were analyzed with Tag-it Violet. For in vivo studies, IMCs were transplanted by stereotactic surgery into the cerebellum of PCD mice. We also used sham-operated animals as controls of the surgical effects, as well as their untreated counterparts. Motor behavior of mice was assessed by rotarod test. The Purkinje cell density was measured by immunohistochemistry and cell death assessed with the TUNEL technique. We also analyzed the microglial phenotype by immunofluorescence and the expression pattern of inflammation-related genes by qPCR. Parametric tests were applied depending on the specific experiment: one or two way ANOVA and Student's T test.

RESULTS

IMCs were proven to effectively acquire immunosuppressive activity under pathological conditions in vitro, thus acting as MDSCs. Concerning in vivo studios, sham-operated PCD mice suffered detrimental effects in motor coordination, Purkinje cell survival and microglial activation. After intracranial administration of IMCs into the cerebellum of PCD mice, no special benefits were detected in the transplanted animals when compared to untreated mice. Nonetheless, this transplant almost completely prevented the impairments caused by the surgery in PCD mice, probably by the modulation of the inflammatory patterns.

CONCLUSIONS

Our work comprise two main translational findings: (1) IMCs can be directly used as they behave as MDSCs under pathological conditions, thus avoiding their gathering from diseased subjects; (2) IMCs are promising adjuvants when performing neurosurgery.

Multimodal Intraoperative Neurophysiological Monitoring in Cranial and Spinal Tumour Surgeries: A Descriptive Observational Study

Intraoperative neurophysiological monitoring (IONM) involves monitoring the functional integrity of critical brain regions and pathways as well as identifying and preserving functionally viable neural tissues (mapping) during surgery using electrophysiological techniques. Multimodality combines various neurophysiological techniques to optimise diagnostic effectiveness and to improve the outcomes of the surgeries. The present study is a case series with comprehensive and illustrative descriptions of the neurophysiological changes in five neuromonitored cases of cranial and spinal cord tumour surgeries conducted with a multimodal approach. The cases were monitored with somatosensory evoked potentials (SSEP), transcranial motor evoked potentials (TcMEP), and both free run and triggered electromyography (fEMG and tEMG). No false negative outcomes were identified in the cases studied as there was an association of absence of change in SSEP and TcMEP both, with no neurological deficit postoperatively. Two cases were identified as having true positive neuromonitoring alerts. No false positive alerts were found in any case. Multimodal monitoring using SSEP, TcMEP, and EMG (fEMG and tEMG) in cranial and spinal tumour surgeries can improve performance with fewer false-negative and false-positive results. Neuromonitoring approaches used in combination can provide reliable information regarding postoperative neurological outcomes.

Neuroprotective effect of phospholipase A2 from Malaysian Naja sumatrana venom against H2O2-induced cell damage and apoptosis

Oxidative stress is one of the factors involved in the pathogenesis of several neurodegenerative diseases. It has been reported that a secretory phospholipase A2 known as A2-EPTX-NSm1a has lower cytotoxicity in neuronal cells compared to its crude Naja sumatrana venom. In this study, A2-EPTX-NSm1a was tested for its neuroprotective activity on human neuroblastoma cells (SH-SY5Y) differentiated into cholinergic neurons against oxidative stress induced by hydrogen peroxide (H2O2). H2O2 treatment alone increased the caspase-3 and caspase-8 activities, whereas pre-treatment with A2-EPTX-NSm1a reduced the activity of these apoptosis-associated proteins. Moreover, A2-EPTX-NSm1a protects the morphology and ultrastructure of differentiated SH-SY5Y cells in the presence of H2O2. Oxidative stress increased the number of small mitochondria. Further evaluation showed the size of mitochondria with a length below 0.25 µm in oxidative stress conditions is higher than the control group, suggesting mitochondria fragmentation. Pre-treatment with A2-EPTX-NSm1a attenuated the number of mitochondria in cells with H2O2 Furthermore, A2-EPTX-NSm1a altered the expression of several neuroprotein biomarkers of GDNF, IL-8, MCP-1, TIMP-1, and TNF-R1 in cells under oxidative stress induced by H2O2. These findings indicate that anti-apoptosis with mitochondria-related protection, anti-inflammatory effect, and promote expression of important markers for cell survival may underlie the neuroprotective effect of A2-EPTX-NSm1a in cholinergic rich human cells under oxidative stress, a vital role in the neuronal disorder.

Effects of Dimethyl Fumarate on the Karnofsky Performance Status and Serum S100β Level in Newly Glioblastoma Patients: A Randomized, Phase-II, Placebo, Triple Blinded, Controlled Trial: Effect of DMF On the Serum S100β Level and KPS Score of GBM Patients

Background: Glioblastoma (GBM) is the most common primary central nervous system malignancy with a low survival without extra logistics. Currently, there is no definitive chemotherapy among the studied options. This study aims to evaluate the neuroprotective effects of dimethyl fumarate (DMF) on surgical brain injuries in patients treated for GBM. Materials and Methods: This randomized, phase II, placebo, triple-blinded, controlled trial was performed on 36 patients with a diagnosis of GBM. All the patients received DMF (240 mg, three-times per day) or placebo (with the same shape and administration route) one week before surgery. Also, patients in both groups after the operation received standard treatments (radiotherapy plus chemotherapy). In addition, Kanofsky's performance status (KPS) score was evaluated at baseline and one month later. Also, serum S100β was measured 48 hours before and after surgery. Results: There was no significant difference among DMF and control groups with regard to age, gender, and the extent of resections (P˃0.05). The most adverse event in both groups was a headache. Although the serum S100β level was not markedly changed after surgery, the mean KPS in the DMF group was higher than in the control group after surgery. Conclusion: The DMF could be a possible good regime for the treatment of GBM; however, questions are raised regarding its efficacy and application for the addition to standard treatment.

Inhibition of LRRK2-Rab10 Pathway Improves Secondary Brain Injury After Surgical Brain Injury in Rats

Leucine-rich repeat kinase 2 (LRRK2) is considered as a potential target for the treatment of Parkinson's disease. This protein is expressed in the brain and has been associated with various diseases and lysosomal maintenance. Rab10 is a member of the Rab protein GTPase family that has been recently shown to be a kinase substrate of LRRK2. In addition, LRRK2 and its kinase substrate Rab10 constitute a key stress response pathway during lysosomal overload stress. This study aimed to investigate the potential role and mechanism underlying LRRK2 and its kinase substrate Rab10 involving surgical brain injury (SBI). One hundred and forty-four male Sprague-Dawley rats were examined using an SBI model, and some had received the LRRK2-specific inhibitor PF-06447475. Thereafter, western blotting, immunofluorescence, brain water content analysis, neuronal apoptosis assay, and neurological score analysis were conducted. The results showed that after SBI, LRRK2 and phosphorylated Rab10 (p-Rab10) expression in neuronal cells were upregulated, and administration of PF-06447475 significantly reduced neuronal apoptosis, neuroinflammation, and brain water content 12 h after SBI and improved neurological deficit 72 h after SBI, which is related to the decreased expression of LRRK2 and p-Rab10, and the lessening of lysosomal overload stress. Our research suggests that the inhibition of LRRK2 can effectively interfere with the role of p-Rab10 in promoting the secretion of lysosomal hydrolase in lysosomal overload stress after SBI, thereby reducing neuronal apoptosis and inflammation after SBI and playing a major role in brain protection.

Superior Effectiveness of a Newly Developed Nonadherent Polyurethane-Coated Surgical Patty for Hemostasis

Background:

Cotton patty is usually used to aspirate blood and cerebrospinal fluid to maintain a dry field. However, the cotton patty easily adheres to the vessels by capillary action, especially in combination with hemostat. Therefore, re-bleeding may be induced by removal of the cotton patty stuck to the vessel despite initial control of the bleeding.

Methods:

We have developed a new cotton patty (Non-Stina X^®, Hakujuji, Co., Ltd., Tokyo, Japan) which does not adhere to the vessels. The newly developed cotton patty is made of 100% cotton, with only the contact surface coated with polyurethane film which prevents capillary action. The coated side includes many holes to allow aspiration from both sides.

Results:

The characteristics of four different surgical patties including our new patty which are available for surgical use in Japan were investigated. Transverse sections of four different surgical patties were investigated by light microscopy (magnification ×150). Our new cotton patty did not show any fluffing on the polyurethane-coated surface. However, other surgical patties showed some fluffing on their surfaces. The friction coefficients of four different surgical patties were investigated. Our new cotton patty had the lowest of the four neurosurgical patties. We confirmed the nonadherent characteristic using with hemostats of gelatinous sponge or fibrin glue-soaked oxidized cellulose cotton during hemostasis in neurosurgical procedures. The polyurethane-coated cotton patty could be removed easily from the hemostats without re-bleeding.

Conclusions:

The newly developed polyurethane-coated cotton patty is more effective for bleeding control from vessels with several types of hemostat due to the nonadherent characteristics.

Stereotactic biopsy for adult brainstem lesions: A surgical approach and its diagnostic value according to the 2016 World Health Organization Classification

BACKGROUND

The brainstem has the critical role of regulating cardiac and respiratory function and it also provides motor and sensory function to the face via the cranial nerves. Despite the observation of a brainstem lesion in a radiological examination, it is difficult to obtain tissues for a pathological diagnosis because of the location and small volume of the brainstem. Thus, we aimed to share our 6-year experience with stereotactic biopsies from brainstem lesions and confirm the value and safety of stereotactic biopsy on this highly eloquent area in this study.

METHODS

We retrospectively reviewed the medical records of 42 adult patients who underwent stereotactic biopsy on brainstem lesions from 2015 to 2020. The radiological findings, surgical records, pathological diagnosis, and postoperative complications of all patients were analyzed.

RESULTS

Histopathological diagnoses were made in 40 (95.2%) patients. Astrocytic tumors were diagnosed in 29 (69.0%) patients, diffuse large B cell lymphoma in 5 (11.9%) patients, demyelinating disease in 4 (9.5%) patients, germinoma in 1 (2.4%) patient, and radiation necrosis in 1 (2.4%) patient. In the 40 patients with successful stereotactic biopsy, 10 (25.0%) patients had inconsistent preoperative radiological diagnosis and postoperative pathological diagnosis. In addition, there was a difference between the treatments prescribed by the radiological and pathological diagnoses in 8 out of 10 patients whose diagnoses changed after biopsy. There was no operative mortality among the 42 patients.

CONCLUSIONS

A pathological diagnosis can be made safely and efficiently in brainstem lesions using stereotactic biopsy. This pathological diagnosis will enable patients to receive appropriate treatment.

Lipid Peroxidation and Antioxidant Consumption as Early Markers of Neurosurgery-Related Brain Injury in Children

BACKGROUND AND AIMS

Lipid peroxidation represents a marker of secondary brain injury both in traumatic and in non-traumatic conditions-as in major neurosurgical procedures-eventually leading to brain edema amplification and further brain damage. Malondialdehyde (MDA), a lipid peroxidation marker, and ascorbate, a marker of antioxidant status, can represent early indicators of this process within the cerebrospinal fluid (CSF). We hypothesized that changes in cerebral lipid peroxidation can be measured ex vivo following neurosurgery in children.

METHODS

Thirty-six children (M:F = 19/17, median age 32.9 months; IQR 17.6-74.6) undergoing neurosurgery for brain tumor removal were admitted to the pediatric intensive care unit (PICU) in the postoperative period with an indwelling intraventricular catheter for intracranial pressure monitoring and CSF drainage. Plasma and CSF samples were obtained for serial measurement of MDA, ascorbate, and cytokines.

RESULTS

An early brain-limited increase in lipid peroxidation was measured, with a significant increase from baseline of MDA in CSF (p = 0.007) but not in plasma. In parallel, ascorbate in CSF decreased (p = 0.05). Systemic inflammatory response following brain surgery was evidenced by plasma IL-6/IL-8 increase (p 0.0022 and 0.0106, respectively). No correlation was found between oxidative response and tumor site or histology (according to World Health Organization grading). Similarly, lipid peroxidation was unrelated to the length of surgery (mean 321 ± 73 min), or intraoperative blood loss (mean 20.9 ± 16.8% of preoperative volemia, 44% given hemotransfusions). Median PICU stay was 3.5 days (IQL range 2-5.5 d.), and postoperative ventilation need was 24 h (IQL range 20-61.5 h). The elevation in postoperative MDA in CSF compared with preoperative values correlated significantly with postoperative ventilation need (P = 0.05, r² 0168), while no difference in PICU stay was recorded.

CONCLUSIONS

Our results indicate that lipid peroxidation increases consistently following brain surgery, and it is accompanied by a decrease in antioxidant defences; intraventricular catheterization offers a unique chance of oxidative process monitoring. Further studies are needed to evaluate whether monitoring post-neurosurgical oxidative stress in CSF is of prognostic utility.

The importance of axonal directions in the brainstem injury during neurosurgical interventions

Brainstem, which connects the distal part of the brain and the spinal cord, contains main motor and sensory nerves and facilitates communication between the cerebrum, cerebellum, and spinal cord. Due to the complicated anatomy and neurostructure of brainstem, surgical interventions to resect brainstem tumors are particularly challenging, and new approaches to reduce the risk of surgical brain injury are of utmost importance. Although previous studies have investigated the structural anisotropy of brain white matter, the effect of axonal fibers on the mechanical properties of white matter has not yet been fully understood. The current study aims to compare the effect of axonal orientation on changes in material properties of brainstem under large deformations and failure through a novel approach. Using diffusion tensor imaging (DTI) on ex-vivo bovine brains, we determined the orientation of axons in brainstem. We extracted brainstem samples in two orthogonal directions, parallel and perpendicular to the axons, and subjected to uniaxial tension to reach the failure at loading rates of 50 mm/min and 150 mm/min. The results showed that the tearing energy and failure strain of samples with axons parallel to the force direction were approximately 1.5 times higher than the samples with axons perpendicular to the force direction. The results also revealed that as the sample's initial length increases, its failure strain decreases. These results emphasize the importance of the axon orientation in the mechanical properties of brainstem, and suggest that considering the directional-dependent behavior for this tissue could help to propose new surgical interventions for reducing the risk of injury during tumor resection.

Real-Time Intraoperative Pressure Monitoring to Avoid Surgically Induced Localized Brain Injury Using a Miniaturized Piezoresistive Pressure Sensor

Neurosurgical procedures often cause damage to the brain tissue at the periphery from surgical manipulations. Especially during retraction, a large amount of pressure could be applied on the brain surface, which can damage it, leading to brain herniation, which can be fatal for patients. To resolve this issue, we have developed a pressure sensor that can be used to monitor the applied pressure during surgery for intraoperative care. This device was tested on a rodent model to create a superficial surgically induced damage profile for three different applied pressures (30, 50, and 70 mmHg) and compared to a standard intracranial pressure monitoring system. Magnetic resonance imaging has been performed after surgical procedures to detect the herniation caused by applied pressure. To evaluate the damage to brain cells and tissue rupture, histological analysis was performed using hematoxylin and eosin staining. A scoring system was developed to understand the severity of the surgically induced brain injury, which will help neurosurgeons to limit the pressure to an optimum point without causing damage.

The potential of Slit2 as a therapeutic target for central nervous system disorders

Introduction: Slit2 is an extracellular matrix protein that regulates migration of developing axons during central nervous system (CNS) development. Roundabout (Robo) receptors expressed by various cell types in the CNS, mediate intracellular signal transduction pathways for Slit2. Recent studies indicate that Slit2 plays important protective roles in a myriad of processes such as cell migration, immune response, vascular permeability, and angiogenesis in CNS pathologies. Areas covered: This review provides an overview of the diverse functions of Slit2 in CNS disorders and discusses the potential of Slit2 as a therapeutic target. We reviewed preclinical studies reporting the role of Slit2 in various CNS disease models, transgenic animal research, and rodent models that utilized Slit2 as a therapy. Expert opinion: Slit2 exerts a wide array of beneficial effects ranging from anti-migration, blood-brain barrier (BBB) protection, inhibition of peripheral immune cell infiltration, and anti-apoptosis in various disease models. However, a dual role of Slit2 in endothelial permeability has been observed in transgenic animals. Further research on Slit2 will be crucial including key issues such as effects of transgenic overexpression versus exogenous Slit2, function of Slit2 dependent on cellular expression of Robo receptors and the underlying pathology for potential clinical translation.

Overexpression of Mfsd2a attenuates blood brain barrier dysfunction via Cav-1/Keap-1/Nrf-2/HO-1 pathway in a rat model of surgical brain injury

INTRODUCTION

Disruption of the blood brain barrier (BBB) and subsequent cerebral edema formation is one of the major adverse effects of brain surgery, leading to postoperative neurological dysfunction. Recently, Mfsd2a has been shown to have a crucial role for the maintenance of BBB functions. In this study, we aimed to evaluate the role of Mfsd2a on BBB disruption following surgical brain injury (SBI) in rats.

MATERIALS AND METHODS

Rats were subjected to SBI by partial resection of the right frontal lobe. To evaluate the effect of Mfsd2a on BBB permeability and neurobehavior outcome following SBI, Mfsd2a was either overexpressed or downregulated in the brain by administering Mfsd2a CRISPR activation or knockout plasmids, respectively. The potential mechanism of Mfsd2a-mediated BBB protection through the cav-1/Nrf-2/HO-1 signaling pathway was evaluated.

RESULTS

Mfsd2a levels were significantly decreased while cav-1, Nrf-2 and HO-1 levels were increased in the right frontal perisurgical area following SBI. When overexpressed, Mfsd2a attenuated brain edema and abolished neurologic impairment caused by SBI while downregulation of Mfsd2a expression further deteriorated BBB functions and worsened neurologic performance following SBI. The beneficial effect of Mfsd2a overexpression on BBB functions was associated with diminished expression of cav-1, increased Keap-1/Nrf-2 dissociation and further augmented levels of Nrf-2 and HO-1 in the right frontal perisurgical area, leading to enhanced levels of tight junction proteins following SBI. The BBB protective effect of Mfsd2a was blocked by selective inhibitors of Nrf-2 and HO-1.

CONCLUSIONS

Mfsd2a attenuates BBB disruption through cav-1/Nrf-2/HO-1 signaling pathway in rats subjected to experimental SBI.

Modification of kynurenine pathway via inhibition of kynurenine hydroxylase attenuates surgical brain injury complications in a male rat model

Neurosurgical procedures result in surgically induced brain injury (SBI) that causes postoperative complications including brain edema and neuronal apoptosis in the surrounding brain tissue. SBI leads to the release of cytokines that indirectly cause the stimulation of kynurenine 3-monooxygenase (KMO) and the release of neurotoxic quinolinic acid (QUIN). This study tested a KMO inhibitor, RO 61-8048, to prevent postoperative brain edema and consequent neuronal apoptosis in an in vivo model of SBI. A rodent model of SBI was utilized which involves partial resection of the right frontal lobe. A total of 127 Sprague-Dawley male rats (weight 275-325 g) were randomly divided into the following groups: Sham surgical group, SBI, SBI + DMSO, SBI + RO 61-8048 (10 mg/kg), SBI + RO 61-8048 (40 mg/kg), and SBI + RO 61-8048 (40 mg/kg) + KAT II inhibitor PF-04859989 (5 mg/kg). RO 61-8048 was administered by intraperitoneal injection after SBI. Postoperative assessment at different time points included brain water content (brain edema), neurological scoring, and western blot. SBI increased brain water content (ipsilateral frontal lobe), decreased neurological function, and increased apoptotic markers compared with sham animals. Treatment with RO 61-8048 (40 mg/kg) reduced brain water content and improved long-term neurological function after SBI. RO 61-8048 increased the expression of kynurenic acid while reducing QUIN and apoptotic markers in the surrounding brain tissue after SBI. These neuroprotective effects were reversed by PF-04859989. This study suggests KMO inhibition via RO 61-8048 as a potential postoperative therapy following neurosurgical procedures.

Neurotrophin-3 provides neuroprotection via TrkC receptor dependent pErk5 activation in a rat surgical brain injury model

BACKGROUND

Surgical brain injury (SBI) which occurs due to the inadvertent injury inflicted to surrounding brain tissue during neurosurgical procedures can potentiate blood brain barrier (BBB) permeability, brain edema and neurological deficits. This study investigated the role of neurotrophin 3 (NT-3) and tropomyosin related kinase receptor C (TrkC) against brain edema and neurological deficits in a rat SBI model.

METHODS

SBI was induced in male Sprague Dawley rats by partial right frontal lobe resection. Temporal expression of endogenous NT-3 and TrkC was evaluated at 6, 12, 24 and 72 h after SBI. SBI rats received recombinant NT-3 which was directly applied to the brain surgical injury site using gelfoam. Brain edema and neurological function was evaluated at 24 and 72 h after SBI. Small interfering RNA (siRNA) for TrkC and Rap1 was administered via intracerebroventricular injection 24 h before SBI. BBB permeability assay and western blot was performed at 24 h after SBI.

RESULTS

Endogenous NT-3 was decreased and TrkC expression increased after SBI. Topical administration of recombinant NT-3 reduced brain edema, BBB permeability and improved neurological function after SBI. Recombinant NT-3 administration increased the expression of phosphorylated Rap1 and Erk5. The protective effect of NT-3 was reversed with TrkC siRNA but not Rap1 siRNA.

CONCLUSIONS

Topical application of NT-3 reduced brain edema, BBB permeability and improved neurological function after SBI. The protective effect of NT-3 was possibly mediated via TrkC dependent activation of Erk5.

Traumatic brain injury: classification, models, and markers

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide. Due to its high incidence rate and often long-term sequelae, TBI contributes significantly to increasing costs of health care expenditures annually. Unfortunately, advances in the field have been stifled by patient and injury heterogeneity that pose a major challenge in TBI prevention, diagnosis, and treatment. In this review, we briefly discuss the causes of TBI, followed by its prevalence, classification, and pathophysiology. The current imaging detection methods and animal models used to study brain injury are examined. We discuss the potential use of molecular markers in detecting and monitoring the progression of TBI, with particular emphasis on microRNAs as a novel class of molecular modulators of injury and its repair in the neural tissue.

Recombinant Slit2 Reduces Surgical Brain Injury Induced Blood Brain Barrier Disruption via Robo4 Dependent Rac1 Activation in a Rodent Model

Brain tissue surrounding surgical resection site can be injured inadvertently due to procedures such as incision, retractor stretch, and electrocauterization when performing neurosurgical procedures, which is termed as surgical brain injury (SBI). Blood brain barrier (BBB) disruption due to SBI can exacerbate brain edema in the post-operative period. Previous studies showed that Slit2 exhibited vascular anti-permeability effects outside the brain. However, BBB protective effects of Slit2 following SBI has not been evaluated. The objective of this study was to evaluate whether recombinant Slit2 via its receptor roundabout4 (Robo4) and the adaptor protein, Paxillin were involved in reducing BBB permeability in SBI rat model. Our results showed that endogenous Slit2 increased in the surrounding peri-resection brain tissue post-SBI, Robo4 remained unchanged and Paxillin showed a decreasing trend. Recombinant Slit2 administered 1 h before injury increased BBB junction proteins, reduced BBB permeability, and decreased neurodeficits 24 h post-SBI. Furthermore, recombinant Slit2 administration increased Rac1 activity which was reversed by Robo4 and Paxillin siRNA. Our findings suggest that recombinant Slit2 reduced SBI-induced BBB permeability, possibly by stabilizing BBB tight junction via Robo4 mediated Rac1 activation. Slit2 may be beneficial for BBB protection during elective neurosurgeries.

Crotalus helleri venom preconditioning reduces postoperative cerebral edema and improves neurological outcomes after surgical brain injury

INTRODUCTION

Postoperative cerebral edema is a devastating complication in neurosurgical patients. Loss of blood-brain barrier integrity has been shown to lead to the development of brain edema following neurosurgical procedures. The aim of this study was to evaluate preconditioning with Crotalus helleri venom (Cv-PC) as a potential preventive therapy for reducing postoperative brain edema in the rodent SBI model. C. helleri venom is known to contain phospholipase A2 (PLA2), an enzyme upstream to cyclooxygenase-2 (COX-2) in the inflammatory cascade, acts to increase the production of inflammatory mediators, such as prostaglandins. We hypothesize that Cv-PC will downregulate the response of the COX-2 pathway to injury, thereby reducing the inflammatory response and the development of brain edema after SBI.

MATERIALS AND METHODS

75 male Sprague Dawley rats (280-330g) were divided to the following groups-naïve+vehicle, naïve+Cv-PC, sham, vehicle, Cv-PC, Cv-PC+NS398 (COX-2 inhibitor). Vehicle preconditioned and Cv-PC animals received either three daily subcutaneous doses of saline or C. helleri venom at 72h, 48h, and 24h prior to surgery. In Cv-PC+NS398 animals, NS398 was administered intraperitoneally 1h prior to each Cv-PC injection. Sham-operated animals received craniotomy only, whereas SBI animals received a partial right frontal lobectomy. Neurological testing and brain water content were assessed at 24h and 72h after SBI; COX-2 and PGE₂ expression was assessed at 24h postoperatively by Western blot and immunohistochemistry, respectively.

RESULTS

At 24h after SBI, the vehicle-treated animals were observed to have increased brain water content (83.1±0.2%) compared to that of sham animals (80.2±0.1%). The brain water content of vehicle-treated animals at 72h post-SBI was elevated at 83.3±0.2%. Cv-PC-treated animals with doses of 10% LD₅₀ had significantly reduced brain water content of 81.92±0.7% and 81.82±0.3% at 24h and 72h, respectively, after SBI compared to that of vehicle-treated animals, while Cv-PC with 5% LD₅₀ doses showed brain water content that trended lower but did not reach statistical significance. At 24h and 72h post-SBI, Cv-PC-treated animals had significantly higher neurological score than vehicle-treated animals. The COX-2 over-expression characterized in SBI was attenuated in Cv-PC-treated animals; NS398 reversed the protective effect of Cv-PC on COX-2 expression. Cv-PC tempered the over-expression of the inflammatory marker PGE₂.

CONCLUSION

Our findings indicate that Cv-PC may provide a promising therapy for reducing postoperative edema and improving neurological function after neurosurgical procedures.

Crotalus atrox venom preconditioning increases plasma fibrinogen and reduces perioperative hemorrhage in a rat model of surgical brain injury

Perioperative bleeding is a potentially devastating complication in neurosurgical patients, and plasma fibrinogen concentration has been identified as a potential modifiable risk factor for perioperative bleeding. The aim of this study was to evaluate preconditioning with Crotalus atrox venom (Cv-PC) as potential preventive therapy for reducing perioperative hemorrhage in the rodent model of surgical brain injury (SBI). C. atrox venom contains snake venom metalloproteinases that cleave fibrinogen into fibrin split products without inducing clotting. Separately, fibrinogen split products induce fibrinogen production, thereby elevating plasma fibrinogen levels. Thus, the hypothesis was that preconditioning with C. atrox venom will produce fibrinogen spilt products, thereby upregulating fibrinogen levels, ultimately improving perioperative hemostasis during SBI. We observed that Cv-PC SBI animals had significantly reduced intraoperative hemorrhage and postoperative hematoma volumes compared to those of vehicle preconditioned SBI animals. Cv-PC animals were also found to have higher levels of plasma fibrinogen at the time of surgery, with unchanged prothrombin time. Cv-PC studies with fractions of C. atrox venom suggest that snake venom metalloproteinases are largely responsible for the improved hemostasis by Cv-PC. Our findings indicate that Cv-PC increases plasma fibrinogen levels and may provide a promising therapy for reducing perioperative hemorrhage in elective surgeries.

Hyperbaric Environment: Oxygen and Cellular Damage versus Protection

The elevation of tissue pO2 induced by hyperbaric oxygen (HBO) is a physiological stimulus that elicits a variety of cellular responses. These effects are largely mediated by, or in response to, an increase in the production of reactive oxygen and nitrogen species (RONS). The major consequences of elevated RONS include increased oxidative stress and enhanced antioxidant capacity, and modulation of redox-sensitive cell signaling pathways. Interestingly, these phenomena underlie both the therapeutic and potentially toxic effects of HBO. Emerging evidence indicates that supporting mitochondrial health is a potential method of enhancing the therapeutic efficacy of, and preventing oxygen toxicity during, HBO. This review will focus on the cellular consequences of HBO, and explore how these processes mediate a delicate balance of cellular protection versus damage. © 2017 American Physiological Society. Compr Physiol 7:213-234, 2017.

Could Intrathymic Injection of Myelin Basic Protein Suppress Inflammatory Response After Co-culture of T Lymphocytes and BV-2 Microglia Cells?

BACKGROUND

The interaction between activated microglia and T lymphocytes can yield abundant pro-inflammatory cytokines. Our previous study proved that thymus immune tolerance could alleviate the inflammatory response. This study aimed to investigate whether intrathymic injection of myelin basic protein (MBP) in mice could suppress the inflammatory response after co-culture of T lymphocytes and BV-2 microglia cells.

METHODS

Totally, 72 male C57BL/6 mice were randomly assigned to three groups (n = 24 in each): Group A: intrathymic injection of 100 μl MBP (1 mg/ml); Group B: intrathymic injection of 100 μl phosphate-buffered saline (PBS); and Group C: sham operation group. Every eight mice in each group were sacrificed to obtain the spleen at postoperative days 3, 7, and 14, respectively. T lymphocytes those were extracted and purified from the spleens were then co-cultured with activated BV-2 microglia cells at a proportion of 1:2 in the medium containing MBP for 3 days. After identified the T lymphocytes by CD3, surface antigens of T lymphocytes (CD4, CD8, CD152, and CD154) and BV-2 microglia cells (CD45 and CD54) were detected by flow cytometry. The expressions of pro-inflammatory factors of BV-2 microglia cells (interleukin [IL]-1β, tumor necrosis factor-α [TNF-α], and inducible nitric oxide synthase [iNOS]) were detected by quantitative real-time polymerase chain reaction (PCR). One-way analysis of variance (ANOVA) and the least significant difference test were used for data analysis.

RESULTS

The levels of CD152 in Group A showed an upward trend from the 3rd to 7th day, with a downward trend from the 7th to 14th day (20.12 ± 0.71%, 30.71 ± 1.14%, 13.50 ± 0.71% at postoperative days 3, 7, and 14, respectively, P < 0.05). The levels of CD154 in Group A showed a downward trend from the 3rd to 7th day, with an upward trend from the 7th to 14th day (10.00 ± 0.23%, 5.28 ± 0.69%, 14.67 ± 2.71% at postoperative days 3, 7, and 14, respectively, P < 0.05). The ratio of CD4+/CD8 + T in Group A showed a downward trend from the 3rd to 7th day, with the minimum at postoperative day 7, then an upward trend from the 7th to 14th day (P < 0.05). Meanwhile, the levels of CD45 and CD54 in Group A were found as the same trend as the ratio of CD4+/CD8 + T (CD45: 83.39 ± 2.56%, 82.74 ± 2.09%, 87.56 ± 2.11%; CD54: 3.80 ± 0.24%, 0.94 ± 0.40%, 3.41 ± 0.33% at postoperative days 3, 7, and 14, respectively, P < 0.05). The expressions of TNF-α, IL-1β, and iNOS in Group A were significantly lower than those in Groups B and C, and the values at postoperative day 7 were the lowest compared with those at postoperative days 3 and 14 (P < 0.05). No significant difference was found between Groups B and C.

CONCLUSIONS

Intrathymic injection of MBP could suppress the immune reaction that might reduce the secondary immune injury of brain tissue induced by an inflammatory response.

Epsilon Aminocaproic Acid Pretreatment Provides Neuroprotection Following Surgically Induced Brain Injury in a Rat Model

Neurosurgical procedures can damage viable brain tissue unintentionally by a wide range of mechanisms. This surgically induced brain injury (SBI) can be a result of direct incision, electrocauterization, or tissue retraction. Plasmin, a serine protease that dissolves fibrin blood clots, has been shown to enhance cerebral edema and hemorrhage accumulation in the brain through disruption of the blood brain barrier. Epsilon aminocaproic acid (EAA), a recognized antifibrinolytic lysine analogue, can reduce the levels of active plasmin and, in doing so, potentially can preserve the neurovascular unit of the brain. We investigated the role of EAA as a pretreatment neuroprotective modality in a SBI rat model, hypothesizing that EAA therapy would protect brain tissue integrity, translating into preserved neurobehavioral function. Male Sprague-Dawley rats were randomly assigned to one of four groups: sham (n = 7), SBI (n = 7), SBI with low-dose EAA, 150 mg/kg (n = 7), and SBI with high-dose EAA, 450 mg/kg (n = 7). SBI was induced by partial right frontal lobe resection through a frontal craniotomy. Postoperative assessment at 24 h included neurobehavioral testing and measurement of brain water content. Results at 24 h showed both low- and high-dose EAA reduced brain water content and improved neurobehavioral function compared with the SBI groups. This suggests that EAA may be a useful pretherapeutic modality for SBI. Further studies are needed to clarify optimal therapeutic dosing and to identify mechanisms of neuroprotection in rat SBI models.

Propofol Pretreatment Fails to Provide Neuroprotection Following a Surgically Induced Brain Injury Rat Model

Neurosurgical procedures are associated with unintentional damage to the brain during surgery, known as surgically induced brain injuries (SBI), which have been implicated in orchestrating structural and neurobehavioral deterioration. Propofol, an established hypnotic anesthetic agent, has been shown to ameliorate neuronal injury when given after injury in a number of experimental brain studies. We tested the hypothesis that propofol pretreatment confers neuroprotection against SBI and will reduce cerebral edema formation and neurobehavioral deficits in our rat population. Sprague-Dawley rats were treated with low- and high-dose propofol 30 min before SBI. At 24 h post injury, brain water content and neurobehavioral assessment was conducted based on previously established models. In vehicle-treated rats, SBI resulted in significant cerebral edema and higher neurological deficit scores compared with sham-operated rats. Low- or high-dose propofol therapy neither reduced cerebral edema nor improved neurologic function. The results suggest that propofol pretreatment fails to provide neuroprotection in SBI rats. However, it is possible that a SBI model with less magnitude of injury or that propofol re-dosing, given the short-acting pharmacokinetic property of propofol, may be needed to provide definitive conclusions.

Recombinant Slit2 attenuates neuroinflammation after surgical brain injury by inhibiting peripheral immune cell infiltration via Robo1-srGAP1 pathway in a rat model

BACKGROUND AND PURPOSE

Peripheral immune cell infiltration to the brain tissue at the perisurgical site can promote neuroinflammation after surgical brain injury (SBI). Slit2, an extracellular matrix protein, has been reported to reduce leukocyte migration. This study evaluated the effect of recombinant Slit2 and the role of its receptor roundabout1 (Robo1) and its downstream mediator Slit-Robo GTPase activating protein 1 (srGAP1)-Cdc42 on peripheral immune cell infiltration after SBI in a rat model.

METHODS

One hundred and fifty-three adult male Sprague-Dawley rats (280-350 g) were used. Partial resection of right frontal lobe was performed to induce SBI. Slit2 siRNA was administered by intracerebroventricular injection 24h before SBI. Recombinant Slit2 was injected intraperitoneally 1h before SBI. Recombinant Robo1 used as a decoy receptor was co-administered with recombinant Slit2. srGAP1 siRNA was administered by intracerebroventricular injection 24h before SBI. Post-assessments included brain water content measurement, neurological tests, ELISA, Western blot, immunohistochemistry, and Cdc42 activity assay.

RESULTS

Endogenous Slit2 was increased after SBI. Robo1 was expressed by peripheral immune cells. Endogenous Slit2 knockdown worsened brain edema after SBI. Recombinant Slit2 administration reduced brain edema, neurological deficits, and pro-inflammatory cytokines after SBI. Recombinant Slit2 reduced peripheral immune cell markers cluster of differentiation 45 (CD45) and myeloperoxidase (MPO), as well as Cdc42 activity in the perisurgical brain tissue which was reversed by recombinant Robo1 co-administration and srGAP1 siRNA.

CONCLUSIONS

Recombinant Slit2 improved outcomes by reducing neuroinflammation after SBI, possibly by decreasing peripheral immune cell infiltration to the perisurgical site through Robo1-srGAP1 mediated inhibition of Cdc42 activity. These results suggest that Slit2 may be beneficial to reduce SBI-induced neuroinflammation.

Correlation between subacute sensorimotor deficits and brain water content after surgical brain injury in rats

Brain edema is a major contributor to poor outcome and reduced quality of life after surgical brain injury (SBI). Although SBI pathophysiology is well-known, the correlation between cerebral edema and neurological deficits has not been thoroughly examined in the rat model of SBI. Thus, the purpose of this study was to determine the correlation between brain edema and deficits in standard sensorimotor neurobehavior tests for rats subjected to SBI. Sixty male Sprague-Dawley rats were subjected to either sham surgery or surgical brain injury via partial frontal lobectomy. All animals were tested for neurological deficits 24 post-SBI and fourteen were also tested 72 h after surgery using seven common behavior tests: modified Garcia neuroscore (Neuroscore), beam walking, corner turn test, forelimb placement test, adhesive removal test, beam balance test, and foot fault test. After assessing the functional outcome, animals were euthanized for brain water content measurement. Surgical brain injury resulted in significantly elevated frontal lobe brain water content 24 and 72 h after surgery compared to that of sham animals. In all behavior tests, significance was observed between sham and SBI animals. However, a correlation between brain water content and functional outcome was observed for all tests except Neuroscore. The selection of behavior tests is critical to determine the effectiveness of therapeutics. Based on this study's results, we recommend using beam walking, the corner turn test, the beam balance test, and the foot fault test since correlations with brain water content were observed at both 24 and 72 h post-SBI.

Neuroprotective effects of GDNF-expressing human amniotic fluid cells

Brain injury continues to be one of the leading causes of disability worldwide. Despite decades of research, there is currently no pharmacologically effective treatment for preventing neuronal loss and repairing the brain. As a result, novel therapeutic approaches, such as cell-based therapies, are being actively pursued to repair tissue damage and restore neurological function after injury. In this study, we examined the neuroprotective potential of amniotic fluid (AF) single cell clones, engineered to secrete glial cell derived neurotrophic factor (AF-GDNF), both in vitro and in a surgically induced model of brain injury. Our results show that pre-treatment with GDNF significantly increases cell survival in cultures of AF cells or cortical neurons exposed to hydrogen peroxide. Since improving the efficacy of cell transplantation depends on enhanced graft cell survival, we investigated whether AF-GDNF cells seeded on polyglycolic acid (PGA) scaffolds could enhance graft survival following implantation into the lesion cavity. Encouragingly, the AF-GDNF cells survived longer than control AF cells in serum-free conditions and continued to secrete GDNF both in vitro and following implantation into the injured motor cortex. AF-GDNF implantation in the acute period following injury was sufficient to activate the MAPK/ERK signaling pathway in host neural cells in the peri-lesion area, potentially boosting endogenous neuroprotective pathways. These results were complemented with promising trends in beam walk tasks in AF-GDNF/PGA animals during the 7 day timeframe. Further investigation is required to determine whether significant behavioural improvement can be achieved at a longer timeframe.

Preconditioning provides neuroprotection in models of CNS disease: paradigms and clinical significance

Preconditioning is a phenomenon in which brief episodes of a sublethal insult induce robust protection against subsequent lethal injuries. Preconditioning has been observed in multiple organisms and can occur in the brain as well as other tissues. Extensive animal studies suggest that the brain can be preconditioned to resist acute injuries, such as ischemic stroke, neonatal hypoxia/ischemia, surgical brain injury, trauma, and agents that are used in models of neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. Effective preconditioning stimuli are numerous and diverse, ranging from transient ischemia, hypoxia, hyperbaric oxygen, hypothermia and hyperthermia, to exposure to neurotoxins and pharmacological agents. The phenomenon of "cross-tolerance," in which a sublethal stress protects against a different type of injury, suggests that different preconditioning stimuli may confer protection against a wide range of injuries. Research conducted over the past few decades indicates that brain preconditioning is complex, involving multiple effectors such as metabolic inhibition, activation of extra- and intracellular defense mechanisms, a shift in the neuronal excitatory/inhibitory balance, and reduction in inflammatory sequelae. An improved understanding of brain preconditioning should help us identify innovative therapeutic strategies that prevent or at least reduce neuronal damage in susceptible patients. In this review, we focus on the experimental evidence of preconditioning in the brain and systematically survey the models used to develop paradigms for neuroprotection, and then discuss the clinical potential of brain preconditioning.

Therapeutic potential of amniotic fluid-derived cells for treating the injured nervous system

There is a need for improved therapy for acquired brain injury, which has proven resistant to treatment by numerous drugs in clinical trials and continues to represent one of the leading causes of disability worldwide. Research into cell-based therapies for the treatment of brain injury is growing rapidly, but the ideal cell source has yet to be determined. Subpopulations of cells found in amniotic fluid, which is readily obtained during routine amniocentesis, can be easily expanded in culture, have multipotent differentiation capacity, are non-tumourigenic, and avoid the ethical complications associated with embryonic stem cells, making them a promising cell source for therapeutic purposes. Beneficial effects of amniotic fluid cell transplantation have been reported in various models of nervous system injury. However, evidence that amniotic fluid cells can differentiate into mature, functional neurons in vivo and incorporate into the existing circuitry to replace lost or damaged neurons is lacking. The mechanisms by which amniotic fluid cells improve outcomes after experimental nervous system injury remain unclear. However, studies reporting the expression and release of neurotrophic, angiogenic, and immunomodulatory factors by amniotic fluid cells suggest they may provide neuroprotection and (or) stimulate endogenous repair and remodelling processes in the injured nervous system. In this paper, we address recent research related to the neuronal differentiation of amniotic fluid-derived cells, the therapeutic efficacy of these cells in animal models of nervous system injury, and the possible mechanisms mediating the positive outcomes achieved by amniotic fluid cell transplantation.

Protecting the brain during neurosurgical procedures: strategies that can work

PURPOSE OF REVIEW

The quest for neuroprotection strategies during periods of neuronal vulnerability persists despite decades of basic and clinical research. This review will focus on the latest developments in the area of clinical brain protection with the major emphasis on strategies that can be beneficial during neurosurgical procedures.

RECENT FINDINGS

Brain protection in neurosurgical patients may be achieved by nonpharmacological and pharmacological strategies. Pharmacological neuroprotection including anaesthetic administration have not been recently shown to be successful. Alternatively, nonpharmacological strategies including maintenance of cerebral perfusion by adequate control of mean arterial pressure (≥80 mmHg), liberal normoglycaemia (7.8-10 mmol/l), adequate haemoglobin levels (preoperative ≥120 g/l and intraoperative ≥90 g/l) and induction of hypertension (20-40% of preoperative values) in certain neurosurgical situations can be beneficial as neuroprotectants during neurosurgery. Mild hypothermia (32-35°C) failed to achieve neuroprotective effects in several situations of brain injury.

SUMMARY

The findings of this review suggest that the anaesthesiologist is compelled to use nonpharmacological strategies sometimes based on empiric evidence to protect the brain during neurosurgical procedures. These strategies are simple, have high benefit/risk ratios and are inexpensive. Rigorous controlled clinical studies are needed to investigate the neuroprotective efficacy of these commonly used nonpharmacological methods.

Surgical brain injury and edema prevention

Neurosurgical procedures, carried out routinely in health institutions, present postoperative complications that result from unavoidable brain injury inflicted by surgical maneuvers. These maneuvers, which include incisions, electrocauterization, and retraction, place brain tissue at the margins of the operative site at risk of injury. Brain edema is a major complication that develops subsequent to this surgically induced brain injury. In the present review, we will discuss type of injury as well as the animal model available to study it. In addition, we will discuss potential mediators, including vascular endothelial growth factor, metalloproteinases, and cyclooxygenases, which have been tested in in vivo experimental studies and have been shown to be potential targets for the development of clinical therapies for neuroprotection against brain edema.

PAR-1 antagonist SCH79797 ameliorates apoptosis following surgical brain injury through inhibition of ASK1-JNK in rats

Neurosurgical procedures inevitably produce intraoperative hemorrhage. The subsequent entry of blood into the brain parenchyma results in the release of large amounts of thrombin, a known contributor to perihematomal edema formation and apoptosis after brain injury. The present study seeks to test 1) the effect of surgically induced brain injury (SBI) on thrombin activity, expression of thrombin's receptor PAR-1, and PAR-1 mediated apoptosis; 2) the effect of thrombin inhibition by argatroban and PAR-1 inhibition by SCH79797 on the development of secondary brain injury in the SBI model on rats. A total of 88 Sprague-Dawley male rats were randomly divided into sham, vehicle-, argatroban-, or SCH79797-treated groups. SBI involved partial resection of the right frontal lobe under inhalation isoflurane anesthesia. Sham-operated animals received only craniotomy. Thrombin activity, brain water content, and neurological deficits were measured at 24 h following SBI. Involvement of the Ask1/JNK pathway in PAR-1-induced post-SBI apoptosis was characterized by using Ask1 or JNK inhibitors. We observed that SBI increased thrombin activity, yet failed to demonstrate any effect on PAR-1 expression. Argatroban and SCH79797 reduced SBI-induced brain edema and neurological deficits in a dose-dependent manner. SBI-induced apoptosis seemed mediated by the PAR-1/Ask1/JNK pathways. Administration of SCH79797 ameliorated the apoptosis following SBI. Our findings indicate that PAR-1 antagonist protects against secondary brain injury after SBI by decreasing both brain edema and apoptosis by inactivating PAR-1/Ask1/JNK pathway. The anti-apoptotic effect of PAR-1 antagonists may provide a promising path for therapy following SBI.

Preoperative mucosal tolerance to brain antigens and a neuroprotective immune response following surgical brain injury

OBJECT

Intracranial surgery causes cortical injury from incisions, hemorrhage, retraction, and electrocautery. The term "surgical brain injury" (SBI) has been developed to categorize this injury inherent to the procedure. Neuroinflammation plays a significant role in SBI. Traditional antiinflammatory therapies are often limited by their immunosuppressive side effects and poor CNS penetration. This study uses mucosal tolerance to develop an immune system that is tolerant to brain myelin basic protein (MBP) so that inflammation can be suppressed in a timely and site-specific manner following surgical disruption of the blood-brain barrier.

METHODS

A standard SBI model using CD57 mice was used. Nasopharyngeal mucosa was exposed to vehicle, ovalbumin, or MBP to develop mucosal tolerance to these antigens. Immunological tolerance to MBP was confirmed in vivo through hypersensitivity testing. Neurological scores, cerebral edema, and interleukin (IL)-1β and transforming growth factor (TGF)-β1 cytokine levels were measured 48 hours postoperatively.

RESULTS

Hypersensitivity testing confirmed the development of immune tolerance to MBP. Myelin basic protein-tolerant mice demonstrated reduced neurological injury, less cerebral edema, decreased levels of IL-1β, and increased levels of TGFβ1 following SBI.

CONCLUSIONS

Developing preoperative immunological tolerance to brain antigens through mucosal tolerance provides neuroprotection, reduces brain edema, and modulates neuroinflammation following SBI.

Mucosal tolerance to brain antigens preserves endogenous TGFβ-1 and improves neurological outcomes following experimental craniotomy

Intracranial surgery causes brain damage from cortical incisions, intraoperative hemorrhage, retraction, and electrocautery; collectively these injuries have recently been coined surgical brain injury (SBI). Inflammation following SBI contributes to neuronal damage. This study develops T-cells that are immunologically tolerant to brain antigen via the exposure of myelin basic protein (MBP) to airway mucosa. We hypothesize that these T-cells will migrate to the site of corticotomy, secrete immunosuppressive cytokines, such as TGFβ1, reduce inflammation, and improve neurological outcomes following SBI. A standard model for SBI was used for this experiment. C57 mice were divided into six groups: SHAM+Vehicle, SHAM+Ovalbumin, SHAM+MBP, SBI+Vehicle, SBI+OVA, and SBI+MBP. Induction of mucosal tolerance to vehicle, ovalbumin, or MBP was performed prior to SBI. Neurological scores and TBFβ1 cytokine levels were measured 48 h postoperatively. Mice receiving craniotomy demonstrated a reduction in neurological score. Animals tolerized to MBP (SBI+MBP) had better postoperative neurological scores than SBI+Vehicle and SBI+OVA. SBI inhibited the cerebral expression TGFβ1 in PBS and OVA treated groups, whereas MBP treated-animals preserved preoperative levels. Mucosal tolerance to MBP leads to significant improvement in neurological outcome that is associated with the preservation of endogenous levels of brain TGFβ1.

Hydrogen is neuroprotective against surgically induced brain injury

Background

Neurosurgical operations cause unavoidable damage to healthy brain tissues. Direct surgical injury as well as surgically induced oxidative stress contributes to the subsequent formation of brain edema. Therefore, we tested the neuroprotective effects of hydrogen (H₂) in an established surgical brain injury (SBI) model in rats.

Materials and methods

Adult male Sprague - Dawley rats (weight 300-350g) were divided into three groups to serve as sham operated, SBI without treatment, and SBI treated with H₂ (2.9%). Brain water content, myeloperoxidase (MPO) assay, lipid peroxidation (LPO), and neurological function were measured at 24 hrs after SBI.

Results

SBI resulted in localized brain edema (p = < 0.001). Hydrogen (2.9%) administered concurrently with surgery significantly decreased the formation of cerebral edema (p = 0.028) and improved neurobehavioral score (p = 0.022). However, hydrogen treatment failed to reduce oxidative stress (LPO assay) or inflammation (MPO assay) in brain tissues.

Conclusions

Hydrogen appears to be promising as an effective, yet inexpensive way to reduce cerebral edema caused by surgical procedures. Hydrogen has the potential to improve clinical outcome, decrease hospital stay, and reduce overall cost to patients and the health care system.

Prostaglandin E2 EP1 receptor inhibition fails to provide neuroprotection in surgically induced brain-injured mice

Recent trials have shown that the prostaglandin E2 EP1 receptor is responsible for NMDA excitotoxicity in the brain after injury. Consequently, in this study, we investigated the use of SC-51089, a selective prostaglandin E2 EP1 receptor antagonist, as a pre-treatment modality to decrease cell death, reduce brain edema, and improve neurobehavioral function after surgically induced brain injury (SBI) in mice. Eleven-week-old C57 black mice (n=82) were randomly assigned to four groups: sham (n=31), SBI (n=27), SBI treated with SC51089 at 10 μg/kg (n=7), and SBI treated with SC51089 at 100 μg/kg (n=17). Treated groups received a single dose of SC51089 intrapertioneally at 12 and 1 h pre-surgery. SBI was performed by resecting the right frontal lobe using a frontal craniotomy. Postoperative assessment occurred at 24 and 72 h, and included neurobehavioral testing and measurement of brain water content and cell death. Results indicated that neither low- nor high-dose EP1 receptor inhibition protected against the SBI-related effects on brain edema formation or cell death. There was however a significant improvement in neurobehavioral function 24 h post-SBI with both dosing regimens. Further studies will be needed to assess the potential therapeutic role of EP1 receptor targeting in SBI.

Granulocyte colony-stimulating factor treatment provides neuroprotection in surgically induced brain injured mice

Surgically induced brain injury (SBI) is a common concern after a neurosurgical procedure. Current treatments aimed at reducing the postoperative sequela are limited. Granulocyte-colony stimulating factor (G-CSF), a hematopoietic growth factor involved in the inflammatory process, has been shown in various animal models to be neuroprotective. Consequently, in this study, we investigated the use of G-CSF as a treatment modality to reduce cell death and brain edema, while improving neurobehavioral deficits following an SBI in mice. Eleven-week-old C57 black mice (n=76) were randomly placed into four groups: sham (n=19), SBI (n=21), SBI with G-CSF pre-treatment (n=15) and SBI with G-CSF pre/post-treatment (n=21). Treated groups received a single dose of G-CSF intraperitoneally at 24, 12 and 1 h pre-surgery and/or 6 and 12 h post-surgery. Postoperative assessment occurred at 24 h and included neurobehavioral testing and measurement for both cell death and brain edema. Results indicated that pre-treatment with G-CSF reduced both cell death and brain edema, while post-treatment reduced neurobehavioral deficits. This study implies that the morphological changes in the brain are effected by pre-treatment; however, in order to activate and/or amplify targets involved in the recovery process, more dosing regimens may be needed.

N-methyl-D-aspartate preconditioning improves short-term motor deficits outcome after mild traumatic brain injury in mice

Traumatic brain injury (TBI) causes impairment of fine motor functions in humans and nonhuman mammals that often persists for months after the injury occurs. Neuroprotective strategies for prevention of the sequelae of TBI and understanding the molecular mechanisms and cellular pathways are related to the glutamatergic system. It has been suggested that cellular damage subsequent to TBI is mediated by the excitatory neurotransmitters, glutamate and aspartate, through the excessive activation of the N-methyl-D-aspartate (NMDA) receptors. Thus, preconditioning with a low dose of NMDA was used as a strategy for protection against locomotor deficits observed after TBI in mice. Male adult mice CF-1 were preconditioned with NMDA (75 mg/kg) 24 hr before the TBI induction. Under anesthesia with O(2)/N(2)O (33%: 66%) inhalation, the animals were subjected to the experimental model of trauma that occurs by the impact of a 25 g weight on the skull. Sensorimotor gating was evaluated at 1.5, 6, or 24 hr after TBI induction by using footprint and rotarod tests. Cellular damage also was assessed 24 hr after occurrence of cortical trauma. Mice preconditioned with NMDA were protected against all motor deficits revealed by footprint tests, but not those observed in rotarod tasks. Although mice showed motor deficits after TBI, no cellular damage was observed. These data corroborate the hypothesis that glutamatergic excitotoxicity, especially via NMDA receptors, contributes to severity of trauma. They also point to a putative neuroprotective mechanism induced by a sublethal dose of NMDA to improve motor behavioral deficits after TBI.

Intraoperative monitoring of cerebral microcirculation and oxygenation--a feasibility study using a novel photo-spectrometric laser-Doppler flowmetry

BACKGROUND

The present study assesses the utility of a novel invasive device (O2C-, oxygen-to-see-device) for intraoperative measurement of the cerebral microcirculation. CO2 vasoreactivity during 2 different propofol concentrations was used to investigate changes of capillary venous cerebral blood flow (rvCBF), oxygen saturation (srvO2), and hemoglobin concentration (rvHb) during craniotomy.

METHODS

Thirty-four patients were randomly assigned to a low propofol (4 mg/kg/h) versus a high propofol (6 mg/kg/h) group. A fiberoptic probe was applied on the cortex next to the surgical site. Measurements were performed during lower (35 mm Hg) and higher (45 mm Hg) levels of partial pressure of carbon dioxide (paCO2). Arterio-venous difference in oxygen concentration (avDO2) and approximated cerebral metabolic rate of oxygen (aCMRO2) were calculated for each paCO2 state. Linear models were fitted to test changes of end points in response to paCO2 and propofol concentration.

RESULTS

In comparison to the lower levels of paCO2, higher levels of paCO2 increased rvCBF (P<0.001), and srvO2 (P=0.002). RvHb remained unchanged during measurements (P=0.325). Calculated avDO2 decreased with increasing paCO2 (P<0.001), whereas aCMRO2 did not change during the study (P=0.999). Propofol concentration had no effect on measured or calculated end points.

CONCLUSIONS

Increase of rvCBF by paCO2 indicates a preserved CO2 reactivity independent of propofol anesthesia. The consecutive rise in srvO2 implies enhanced oxygen availability due to vasodilatation. Unchanged rvHb represents constant venous hemoglobin concentration. As expected, calculated avDO2 decreases with increased paCO2, whereas aCMRO2 remains unchanged. Despite the promising technical approach, the technology needs validation and further investigation for usage during neurosurgery.

Identification and validation of novel spinophilin-associated proteins in rodent striatum using an enhanced ex vivo shotgun proteomics approach

Spinophilin regulates excitatory postsynaptic function and morphology during development by virtue of its interactions with filamentous actin, protein phosphatase 1, and a plethora of additional signaling proteins. To provide insight into the roles of spinophilin in mature brain, we characterized the spinophilin interactome in subcellular fractions solubilized from adult rodent striatum by using a shotgun proteomics approach to identify proteins in spinophilin immune complexes. Initial analyses of samples generated using a mouse spinophilin antibody detected 23 proteins that were not present in an IgG control sample; however, 12 of these proteins were detected in complexes isolated from spinophilin knock-out tissue. A second screen using two different spinophilin antibodies and either knock-out or IgG controls identified a total of 125 proteins. The probability of each protein being specifically associated with spinophilin in each sample was calculated, and proteins were ranked according to a chi(2) analysis of the probabilities from analyses of multiple samples. Spinophilin and the known associated proteins neurabin and multiple isoforms of protein phosphatase 1 were specifically detected. Multiple, novel, spinophilin-associated proteins (myosin Va, calcium/calmodulin-dependent protein kinase II, neurofilament light polypeptide, postsynaptic density 95, alpha-actinin, and densin) were then shown to interact with GST fusion proteins containing fragments of spinophilin. Additional biochemical and transfected cell imaging studies showed that alpha-actinin and densin directly interact with residues 151-300 and 446-817, respectively, of spinophilin. Taken together, we have developed a multi-antibody, shotgun proteomics approach to characterize protein interactomes in native tissues, delineating the importance of knock-out tissue controls and providing novel insights into the nature and function of the spinophilin interactome in mature striatum.

Hyperbaric oxygen preconditioning reduces postoperative brain edema and improves neurological outcomes after surgical brain injury

The present study was designed to examine if hyperbaric oxygen preconditioning (HBO-PC) is neuroprotective in a mouse model of surgical brain injury (SBI). C57BL mice were administered 100% oxygen for 1 h at 2.5 ATA for 5 consecutive days and subjected to SBI on the following day. The HBO-PC + SBI animals were compared to sham and normoxia + SBI groups for brain water content in different brain regions at 24 and 72 h after surgery. Blood-brain barrier (BBB) permeability was evaluated using Evan's blue dye extravasation at 24 h. Neurological assessment of the animals was done by a blinded observer at 24 and 72 h. The results showed that brain water content was significantly increased in the right (ipsilateral) frontal lobe surrounding the site of resection. This was attenuated by HBO-PC at 24 and 72 h. However, HBO-PC did not have any effect on the increased BBB permeability observed after SBI. Significant neurological deficits were observed after SBI. HBO-PC improved neurological deficits at 72 h on the 21-point sensorimotor scale and at 24 and 72 h on the wire hang and beam balance scoring. In conclusion, HBO-PC attenuates post-operative brain edema and improves neurological outcomes following SBI.

Dual effects of melatonin on oxidative stress after surgical brain injury in rats

The purpose of this study was to evaluate the effect of melatonin on oxidative stress occurring in the brain after routine lobectomy neurosurgery procedures. Different concentrations of melatonin (5, 15 and 150 mg/kg) were administered 1 hr before lobectomy in a rodent surgical brain injury (SBI) model. Neurological outcomes were assessed 24 hr before the killing of the rodents, for evaluation of brain water content (brain edema) and lipid peroxidation (oxidative stress). The results showed that lower doses (5 and 15 mg/kg) failed to reduce brain edema, but the 15 mg/kg dose did lower oxidative stress and improved several neurological parameters. High concentration of melatonin (150 mg/kg) significantly increased brain edema and elevated oxidative stress when compared with the vehicle-treated group. Furthermore, high-dose melatonin also worsened neurological outcomes compared with other groups. The study suggests that melatonin has dual effects: low-dose melatonin may provide neuroprotective effects against SBI but a high dose may aggravate some parameters after SBI.

Inhibition of NR2B phosphorylation restores alterations in NMDA receptor expression and improves functional recovery following traumatic brain injury in mice

Traumatic brain injury (TBI) triggers a massive glutamate efflux, hyperactivation of N-methyl-D-aspartate receptors (NMDARs) and neuronal cell death. Previously it was demonstrated that, 15 min following experimentally induced closed head injury (CHI), the density of activated NMDARs increases in the hippocampus, and decreases in the cortex at the impact site. Here we show that CHI-induced alterations in activated NMDARs correlate with changes in the expression levels of the major NMDARs subunits. In the hippocampus, the expression of NR1, NR2A, and NR2B subunits as well as the GluR1 subunit of the AMPA receptor (AMPAR) were increased, while in the cortex at the impact site, we found a decrease in the expression of these subunits. We demonstrate that CHI-induced increase in the expression of NMDAR subunits and GluR1 in the hippocampus, but not in the cortex, is associated with an increase in NR2B tyrosine phosphorylation. Furthermore, inhibition of NR2B-phosphorylation by the tyrosine kinase inhibitor PP2 restores the expression of this subunit to its normal levels. Finally, a single injection of PP2, prior to the induction of CHI, resulted in a significant improvement in long-term recovery of motor functions observed in CHI mice. These results provide a new mechanism by which acute trauma contributes to the development of secondary damage and functional deficits in the brain, and suggests a possible role for Src tyrosine kinase inhibitors as preoperative therapy for planned neurosurgical procedures.

Curcuma oil modulates the nitric oxide system response to cerebral ischemia/reperfusion injury

The antioxidant activity of C.oil in cerebral stroke has been reported earlier. We have attempted here to clarify the mechanisms underlying the neuroprotection against experimental cerebral ischemia by Curcuma oil (C.oil), isolated from the rhizomes of Curcuma longa. C.oil (250 mg/kg i.p.) was given 30 min before focal ischemia in rats caused by occlusion of the middle cerebral artery (1h of occlusion, 24h of reflow). Ischemia, leads to elevation in [Ca(2+)] this sets into motion a cascades of ischemic injury which was attenuated by C.oil. C.oil reduced post-ischemic brain neutrophil infiltration in the ischemic area, controlled tissue NOx levels and the neuronal levels of nitric oxide, peroxynitrite and reactive oxygen species when measured after 24h of reflow. Double immunofluorescence staining analysis and Western immunoblot analysis with C.oil treatment showed that the expression of nitric oxide synthase (NOS) isoforms were decreased significantly compared to the untreated ischemia group. Ischemia is associated with increased in TUNEL (TdT-mediated dUTP nick-end labeling) positive cells in brain sections indicating DNA fragmentation. The C.oil treated group showed a significant decrease in numbers of apoptotic cells compared to the untreated ischemia group, as seen in the flowcytometric analysis of the neurons. Results of immunohistochemistry and Western immunoblot indicate that C.oil suppressed the elevated protein level of Bax, and aided mitochondrial translocation and activation of Bcl-2 by altered mitochondrial membrane potential. It also inhibits the cytosolic release of apoptogenic molecules like cytochrome c, inhibits the activation of caspase-3 and the expression of p53 ultimately inhibiting apoptosis. Our observations suggest that high levels of NO generated by NOS isoforms are partially responsible for exacerbating the neuronal damage induced by MCAo by intraluminal filament.

Rosiglitazone, a PPAR gamma agonist, attenuates inflammation after surgical brain injury in rodents

INTRODUCTION

Surgical brain injury (SBI) is unavoidable during many neurosurgical procedures. This inevitable brain injury can result in post-operative complications including brain edema, blood-brain barrier disruption (BBB) and cell death in susceptible areas. Rosiglitazone (RSG), a PPAR-gamma agonist, has been shown to reduce inflammation and provide neuroprotection in experimental models of ischemia and intracerebral hemorrhage. This study was designed to evaluate the neuroprotective effects of RSG in a rodent model of SBI.

METHODS

65 adult male Sprague-Dawley rats were randomly divided into sham, vehicle and treatment groups. RSG was administered intraperitoneally in two dosages (1 mg/kg/dose, 6 mg/kg/dose) 30 min before surgery, and 30 min and 4 h after surgery. Animals were euthanized 24 h following neurological evaluation to assess brain edema and BBB permeability by IgG staining. Inflammation was examined using myeloperoxidase (MPO) assay and double-labeling fluorescent immunohistochemical analysis of IL-1beta and TNF-alpha.

RESULTS

Localized brain edema was observed in tissue surrounding the surgical injury. This brain edema was significantly higher in rats subjected to SBI than sham animals. Increased IgG staining was present in affected brain tissue; however, RSG reduced neither IgG staining nor brain edema. RSG also did not improve neurological status observed after SBI. RSG, however, significantly attenuated MPO activity and qualitatively decreased IL-1beta and TNF-alpha expression compared to vehicle-treated group.

CONCLUSION

SBI causes increased brain edema, BBB disruption and inflammation localized along the periphery of the site of surgical resection. RSG attenuated inflammatory changes, however, did not improve brain edema, BBB disruption and neurological outcomes after SBI.

Matrix metalloproteinase inhibition attenuates brain edema in an in vivo model of surgically-induced brain injury

OBJECTIVE

Neurosurgical procedures can result in brain injury by various means, including direct trauma, hemorrhage, retractor stretch, and electrocautery. This surgically-induced brain injury (SBI) can cause postoperative complications such as brain edema after blood-brain barrier (BBB) disruption. The present study seeks to test a matrix metalloproteinase (MMP) inhibitor for preventing postoperative brain edema and BBB disruption in an in vivo model of surgically-induced brain injury.

METHODS

A rodent model of SBI was used which involves resection of a part of the right frontal lobe. A total of 89 Sprague-Dawley male rats (weight, 300-350 g) were randomly divided into four groups: 1) SBI with vehicle treatment (0.1% dimethyl sulfoxide), 2) SBI with single treatment of MMP inhibitor-1 (an inhibitor of MMP-9 and MMP-2), 3) SBI treated daily (total 3 times) with MMP inhibitor-1, and 4) sham surgical group. Postoperative assessment at different time periods included evaluation of BBB permeability, brain water content (brain edema), neurological scoring, histology, immunohistochemistry, and zymography for MMP enzymatic activity. Temporal magnetic resonance imaging studies were also performed to assess postoperative edema.

RESULTS

The results indicate that SBI caused increased brain water content (ipsilateral frontal lobe) and BBB permeability compared with sham animals. Treatment with MMP inhibitor-1 attenuated MMP-9 and MMP-2 activity and decreased brain water content with preservation of the BBB.

CONCLUSION

Inhibition of MMP-9 and MMP-2 attenuates brain edema and BBB disruption after SBI. The study suggests a potential role for MMP inhibition as preoperative therapy before neurosurgical procedures.

Matrix metalloproteinase inhibition attenuates brain edema after surgical brain injury

BACKGROUND

Neurosurgical operations can result in inevitable brain injury due to the procedure itself. This surgical brain injury (SBI) can cause post-operative complications such as brain edema following blood-brain barrier (BBB) disruption leading to neurological deficits.

METHODS

We tested whether inhibition of matrix metalloproteinases (MMPs) 9 and 2 provided neuroprotection against SBI. A rodent SBI model, which involves a partial frontal lobe resection, was used to evaluate two treatment regimens of MMP inhibitor-1 (inhibitor of MMP-9 and MMP-2); a single dose (5 mg/kg, pretreatment) and daily dose treatment (5 mg/kg x 3, pre- and post-treatment). Postoperative assessment at different time periods included brain water content (brain edema), immunohistochemical analysis, zymography for MMP enzymatic activity, and neurological assessment.

FINDINGS

The results indicate that SBI caused localized edema around the site of surgical resection with concomitant increase in MMP-9 and MMP-2 activity. Both treatment regimens with MMP inhibitor-1 decreased brain edema and attenuated the rise in MMP-9 and MMP-2 activity. An increased expression of MMP-9 was also seen in the neurons and neutrophils in the affected brain tissue at the periphery of surgical resection.

CONCLUSIONS

The study suggests a potential role for MMP inhibition as preoperative therapy before neurosurgical procedures.