Abstract 42: In vivo subcutaneous and orthotopic cancer xenograft modeling in the SRG immunodeficient rat

Human cancer xenografts are a vital tool for understanding tumor biology, growth kinetics, and therapeutic efficacy using animal models. Historically, immunodeficient mice have been the standard rodent species for cancer xenograft modeling. However, an immunodeficient rat that supports a wide variety of human cancer cell types would provide a larger rodent strain for easier surgical manipulation, serial blood sampling, and provide a single model in which efficacy, pharmacokinetics, and toxicology can be performed. We have created a Sprague Dawley Rag2 -/-, Il2rg -/- rat (SRGTM OncoRat®) that provides a highly supportive environment for growing tumors of human origin. The SRG rat lacks B, T, and NK cells and readily supports the growth of multiple human cancer cell lines. The SRG rat is more immunodeficient than the Nude rat, suggesting it may be permissive to a wider variety of human cancer types. Here we demonstrate the utility of the SRG rat for both subcutaneous and orthotopic xenograft modeling. The SRG rat supports the growth of both lung and liver orthotopic cancers. In addition, the SRG rat supports the growth of orthoptic human glioblastoma multiforme in the brain. We use in vivo imaging to visualize tumor establishment and growth in subcutaneous, orthotopic, and metastatic models. Furthermore, our data show the ability of the SRG rat to support the growth of multiple different human cancer cell types subcutaneously in two different matrices, Matrigel® and VitroGel®. These data confirm that the SRG rat is an excellent host for studying human cancer. Our data demonstrate that the SRG rat has a high utility for studies using in vivo imaging, orthotopic tumor implantation, and standard subcutaneous tumor modeling. As the most immunodeficient rat commercially available, the SRG rat supports the growth of multiple human cancer types in a larger rodent strain relative to commercially available mouse models.

Citation Format: Diane Begemann, Aida Javidan, Cynthia Dunn, Nicolas Johnston, R. Grace Walton, Valeriya Steffey, Ian Corbin, Niveen Fulcher, Cleusa De Oliveira, Hu Xu, Mila Uzelac, Andrew Deweyert, John A. Ronald, Susanne Schmid, Matthew O. Hebb, Fallon K. Noto. In vivo subcutaneous and orthotopic cancer xenograft modeling in the SRG immunodeficient rat [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 42.

Development of Brain-Derived Bioscaffolds for Neural Progenitor Cell Culture

Biomaterials derived from brain extracellular matrix (ECM) have the potential to promote neural tissue regeneration by providing instructive cues that can direct cell survival, proliferation, and differentiation. This study focused on the development and characterization of microcarriers derived from decellularized brain tissue (DBT) as a platform for neural progenitor cell culture. First, a novel detergent-free decellularization protocol was established that effectively reduced the cellular content of porcine and rat brains, with a >97% decrease in the dsDNA content, while preserving collagens (COLs) and glycosaminoglycans (GAGs). Next, electrospraying methods were applied to generate ECM-derived microcarriers incorporating the porcine DBT that were stable without chemical cross-linking, along with control microcarriers fabricated from commercially sourced bovine tendon COL. The DBT microcarriers were structurally and biomechanically similar to the COL microcarriers, but compositionally distinct, containing a broader range of COL types and higher sulfated GAG content. Finally, we compared the growth, phenotype, and neurotrophic factor gene expression levels of rat brain-derived progenitor cells (BDPCs) cultured on the DBT or COL microcarriers within spinner flask bioreactors over 2 weeks. Both microcarrier types supported BDPC attachment and expansion, with immunofluorescence staining results suggesting that the culture conditions promoted BDPC differentiation toward the oligodendrocyte lineage, which may be favorable for cell therapies targeting remyelination. Overall, our findings support the further investigation of the ECM-derived microcarriers as a platform for neural cell derivation for applications in regenerative medicine.

Planning System for the Optimization of Electric Field Delivery using Implanted Electrodes for Brain Tumor Control

BACKGROUND

The use of non-ionizing electric fields from low intensity voltage sources (<10 V) to control malignant tumor growth is showing increasing potential as a cancer treatment modality. A method of applying these low intensity electric fields using multiple implanted electrodes within or adjacent to tumor volumes has been termed as intratumoral modulation therapy (IMT).

PURPOSE

This study explores advancements in the previously established IMT optimization algorithm, and the development of a custom treatment planning system for patient specific IMT. The practicality of the treatment planning system is demonstrated by implementing the full optimization pipeline on a brain phantom with robotic electrode implantation, post-operative imaging, and treatment stimulation.

METHODS

The integrated planning pipeline in 3D Slicer begins with importing and segmenting patient magnetic resonance images (MRI) or computed tomography (CT) images. The segmentation process is manual, followed by a semi-automatic smoothing step that allows the segmented brain and tumor mesh volumes to be smoothed and simplified by applying selected filters. Electrode trajectories are planned manually on the patient MRI or CT by selecting insertion and tip coordinates for a chosen number of electrodes. The electrode tip positions, and stimulation parameters (phase shift and voltage) can then be optimized with the custom semi-automatic IMT optimization algorithm where users can select the prescription electric field, voltage amplitude limit, tissue electrical properties, nearby organs at risk, optimization parameters (electrode tip location, individual contact phase shift and voltage), desired field coverage percent, and field conformity optimization. Tables of optimization results are displayed, and the resulting electric field is visualized as a field-map superimposed on the MR or CT image, with 3D renderings of the brain, tumor, and electrodes. Optimized electrode coordinates are transferred to robotic electrode implantation software to enable planning and subsequent implantation of the electrodes at the desired trajectories.

RESULTS

An IMT treatment planning system was developed that incorporates patient specific MRI or CT, segmentation, volume smoothing, electrode trajectory planning, electrode tip location and stimulation parameter optimization, and results visualization. All previous manual pipeline steps operating on diverse software platforms were coalesced into a single semi-automated 3D Slicer based user interface. Brain phantom validation of the full system implementation was successful in pre-operative planning, robotic electrode implantation, and post-operative treatment planning to adjust stimulation parameters based on actual implant locations. Voltage measurements were obtained in the brain phantom to determine the electrical parameters of the phantom and validate the simulated electric field distribution.

CONCLUSIONS

A custom treatment planning and implantation system for IMT has been developed in this study, and validated on a phantom brain model, providing an essential step in advancing IMT technology towards future clinical safety and efficacy investigations. This article is protected by copyright. All rights reserved.

Cranial nerve and intramedullary spinal malignant peripheral nerve sheath tumor associated with neurofibromatosis-1

Background:

Malignant peripheral nerve sheath tumors (MPNSTs) are uncommon but aggressive neoplasms associated with radiation exposure and neurofibromatosis Type I (NF1). Their incidence is low compared to other nervous system cancers, and intramedullary spinal lesions are exceedingly rare. Only a few case reports have described intramedullary spinal cord MPNST.

Case Description:

We describe the clinical findings, management, and outcome of a young patient with NF1 who developed aggressive cranial nerve and spinal MPNST tumors. This 35-year-old patient had familial NF1 and a history of optic glioma treated with radiation therapy (RT). She developed a trigeminal MPNST that was resected and treated with RT. Four years later, she developed bilateral lower extremity deficits related to an intramedullary cervical spine tumor, treated surgically, and found to be a second MPNST.

Conclusion:

To the best of our knowledge, this is the first report of cranial nerve and intramedullary spinal MPNSTs manifesting in a single patient, and only the third report of a confined intramedullary spinal MPNST. This unusual case is discussed in the context of a contemporary literature review.

Optimization of multi-electrode implant configurations and programming for the delivery of non-ablative electric fields in intratumoral modulation therapy

PURPOSE

Application of low intensity electric fields to interfere with tumor growth is being increasingly recognized as a promising new cancer treatment modality. Intratumoral modulation therapy (IMT) is a developing technology that uses multiple electrodes implanted within or adjacent tumor regions to deliver electric fields to treat cancer. In this study, the determination of optimal IMT parameters was cast as a mathematical optimization problem, and electrode configurations, programming, optimization, and maximum treatable tumor size were evaluated in the simplest and easiest to understand spherical tumor model. The establishment of electrode placement and programming rules to maximize electric field tumor coverage designed specifically for IMT is the first step in developing an effective IMT treatment planning system.

METHODS

Finite element method electric field computer simulations for tumor models with 2 to 7 implanted electrodes were performed to quantify the electric field over time with various parameters, including number of electrodes (2 to 7), number of contacts per electrode (1 to 3), location within tumor volume, and input waveform with relative phase shift between 0 and 2π radians. Homogeneous tissue specific conductivity and dielectric values were assigned to the spherical tumor and surrounding tissue volume. In order to achieve the goal of covering the tumor volume with a uniform threshold of 1 V/cm electric field, a custom least square objective function was used to maximize the tumor volume covered by 1 V/cm time averaged field, while maximizing the electric field in voxels receiving less than this threshold. An additional term in the objective function was investigated with a weighted tissue sparing term, to minimize the field to surrounding tissues. The positions of the electrodes were also optimized to maximize target coverage with the fewest number of electrodes. The complexity of this optimization problem including its non-convexity, the presence of many local minima, and the computational load associated with these stochastic based optimizations led to the use of a custom pattern search algorithm. Optimization parameters were bounded between 0 and 2π radians for phase shift, and anywhere within the tumor volume for location. The robustness of the pattern search method was then evaluated with 50 random initial parameter values.

RESULTS

The optimization algorithm was successfully implemented, and for 2 to 4 electrodes, equally spaced relative phase shifts and electrodes placed equidistant from each other was optimal. For 5 electrodes, up to 2.5 cm diameter tumors with 2.0 V, and 4.1 cm with 4.0 V could be treated with the optimal configuration of a centrally placed electrode and 4 surrounding electrodes. The use of 7 electrodes allow for 3.4 cm diameter coverage at 2.0 V and 5.5 cm at 4.0 V. The evaluation of the optimization method using 50 random initial parameter values found the method to be robust in finding the optimal solution.

CONCLUSIONS

This study has established a robust optimization method for temporally optimizing electric field tumor coverage for IMT, with the adaptability to optimize a variety of parameters including geometrical and relative phase shift configurations.

Expanding the search for genetic biomarkers of Parkinson's disease into the living brain

Altered gene expression related to Parkinson's Disease (PD) has not been described in the living brain, yet this information may support novel discovery pertinent to disease pathophysiology and treatment. This study compared the transcriptome in brain biopsies obtained from living PD and Control patients. To evaluate the novelty of this data, a comprehensive literature review also compared differentially expressed gene (DEGs) identified in the current study with those reported in PD cadaveric brain and peripheral tissues. RNA was extracted from rapidly cryopreserved frontal lobe specimens collected from PD and Control patients undergoing neurosurgical procedures. RNA sequencing (RNA-Seq) was performed and validated using quantitative polymerase chain reaction. DEG data was assessed using bioinformatics and subsequently included within a comparative analysis of PD RNA-Seq studies. 370 DEGs identified in living brain specimens reflected diverse gene groups and included key members of trophic signaling, apoptosis, inflammation and cell metabolism pathways. The comprehensive literature review yielded 7 RNA-Seq datasets generated from blood, skin and cadaveric brain but none from a living brain source. From the current dataset, 123 DEGs were identified only within the living brain and 267 DEGs were either newly found or had distinct directional change in living brain relative to other tissues. This is the first known study to analyze the transcriptome in brain tissue from living PD and Control patients. The data produced using these methods offer a unique, unexplored resource with potential to advance insight into the genetic associations of PD.

Diffuse intrinsic pontine glioma cells are vulnerable to low intensity electric fields delivered by intratumoral modulation therapy

Introduction

Diffuse intrinsic pontine glioma (DIPG) is a high fatality pediatric brain cancer without effective treatment. The field of electrotherapeutics offers new potential for other forms of glioma but the efficacy of this strategy has not been reported for DIPG. This pilot study evaluated the susceptibility of patient-derived DIPG cells to low intensity electric fields delivered using a developing technology called intratumoral modulation therapy (IMT).

Methods

DIPG cells from autopsy specimens were treated with a custom-designed, in vitro IMT system. Computer-generated electric field simulation was performed to quantify IMT amplitude and distribution using continuous, low intensity, intermediate frequency stimulation parameters. Treatment groups included sham, IMT, temozolomide (TMZ) chemotherapy and radiation therapy (RT). The impact of single and multi-modality therapy was compared using spectrophotometric and flow cytometry viability analyses.

Results

DIPG cells exhibited robust, consistent susceptibility to IMT fields that significantly reduced cell viability compared to untreated control levels. The ratio of viable:non-viable DIPG cells transformed from ~ 6:1 in sham-treated to ~ 1.5:1 in IMT-treated conditions. The impact of IMT was similar to that of dual modality TMZ–RT therapy and the addition of IMT to this treatment combination dramatically reduced DIPG cell viability to ~ 20% of control values.

Conclusions

This proof-of-concept study provides a novel demonstration of marked DIPG cell susceptibility to low intensity electric fields delivered using IMT. The potent impact as a monotherapy and when integrated into multi-modality treatment platforms justifies further investigations into the potential of IMT as a critically needed biomedical innovation for DIPG.

Preclinical outcomes of Intratumoral Modulation Therapy for glioblastoma

Glioblastoma (GBM) is the leading cause of high fatality cancer arising within the adult brain. Electrotherapeutic approaches offer new promise for GBM treatment by exploiting innate vulnerabilities of cancer cells to low intensity electric fields. This report describes the preclinical outcomes of a novel electrotherapeutic strategy called Intratumoral Modulation Therapy (IMT) that uses an implanted stimulation system to deliver sustained, titratable, low intensity electric fields directly across GBM-affected brain regions. This pilot technology was applied to in vitro and animal models demonstrating significant and marked reduction in tumor cell viability and a cumulative impact of concurrent IMT and chemotherapy in GBM. No off target neurological effects were observed in treated subjects. Computational modeling predicted IMT field optimization as a means to further bolster treatment efficacy. This sentinel study provides new support for defining the potential of IMT strategies as part of a more effective multimodality treatment platform for GBM.

Staged multi-modality treatment approaches for giant cerebellopontine angle hemangioblastomas

Giant hemangioblastomas (HBs) located in the cerebellopontine angle (CPA) present rare, high risk neurosurgical challenges. En bloc resection has been traditionally recommended for HBs, however this approach may pose unacceptable risk with giant tumors. Alternative treatment strategies have not been well described and the relevant literature is scant. This case review includes an illustrative patient with a giant, symptomatic CPA HB. It was felt that the neurovascular and tumor attributes were favorable for a multi-modality treatment strategy rather than circumferential dissection to remove this formidable tumor. A staged approach consisting of preoperative HB devascularization, debulking and piecemeal resection followed by radiosurgery for a small residuum produced an excellent clinical outcome. Variations of this unconventional multi-modality strategy may reduce the perioperative morbidity of carefully selected patients with giant CPA HBs. A thorough literature review is provided.

Cerebellar liponeurocytoma: a rare intracranial tumor with possible familial predisposition. Case report

The biological origin of cerebellar liponeurocytomas is unknown, and hereditary forms of this disease have not been described. Here, the authors present clinical and histopathological findings of a young patient with a cerebellar liponeurocytoma who had multiple immediate family members who harbored similar intracranial tumors. A 37-year-old otherwise healthy woman presented with a history of progressive headaches. Lipomatous medulloblastoma had been diagnosed previously in her mother and maternal grandfather, and her maternal uncle had a supratentorial liponeurocytoma. MRI revealed a large, poorly enhancing, lipomatous mass emanating from the superior vermis that produced marked compression of posterior fossa structures. An uncomplicated supracerebellar infratentorial approach was used to resect the lesion. Genetic and histopathological analyses of the lesion revealed neuronal, glial, and lipomatous differentiation and confirmed the diagnosis of cerebellar liponeurocytoma. A comparison of the tumors resected from the patient and, 22 years previously, her mother revealed similar features. Cerebellar liponeurocytoma is a poorly understood entity. This report provides novel evidence of an inheritable predisposition for tumor development. Accurate diagnosis and reporting of clinical outcomes and associated genetic and histopathological changes are necessary for guiding prognosis and developing recommendations for patient care.

In Vitro Validation of Intratumoral Modulation Therapy for Glioblastoma

BACKGROUND/AIM

This proof-of-concept study evaluated the antitumor impact of a direct electrical stimulation technique, termed intratumoral modulation therapy (IMT) on glioblastoma (GBM) cells.

MATERIALS AND METHODS

An in vitro IMT model comprised of a calibrated electrode to deliver continuous, low-intensity stimulation within GBM preparations. Viability and apoptosis assays were performed in treated immortalized and patient-derived GBM cells, and post-mitotic neurons. IMT was delivered alone and with temozolomide, or gene silencing of the tumor-promoting chaperone, heat-shock protein 27 (HSP27).

RESULTS

GBM cells, but not neurons, exhibited >40% loss of viability, caspase-3 activation and apoptosis with IMT. Cell death was modest with temozolomide alone (30%) but increased significantly with concomitant IMT (70%). HSP27 silencing alone produced 30% viability loss, with significant enhancement of target knockdown and GBM cell death (65%), when combined with IMT.

CONCLUSION

These findings warrant further evaluation of IMT as a potential novel therapeutic strategy for GBM.

Advances in Neurotrophic Factor and Cell-Based Therapies for Parkinson's Disease: A Mini-Review

Parkinson's disease (PD) affects an estimated 7-10 million people worldwide and remains without definitive or disease-modifying treatment. There have been many recent developments in cell-based therapy (CBT) to replace lost circuitry and provide chronic biological sources of therapeutic agents to the PD-affected brain. Early neural transplantation studies underscored the challenges of immune compatibility, graft integration and the need for renewable, autologous graft sources. Neurotrophic factors (NTFs) offer a potential class of cytoprotective pharmacotherapeutics that may complement dopamine (DA) replacement and CBT strategies in PD. Chronic NTF delivery may be an integral goal of CBT, with grafts consisting of autologous drug-producing (e.g., DA, NTF) cells that are capable of integration and function in the host brain. In this mini-review, we outline the past experience and recent advances in NTF technology and CBT as promising and integrated approaches for the treatment of PD.

HSP27 knockdown produces synergistic induction of apoptosis by HSP90 and kinase inhibitors in glioblastoma multiforme

BACKGROUND/AIM

The heat-shock proteins HSP27 and HSP90 perpetuate the malignant nature of glioblastoma multiforme (GBM) and offer promise as targets for novel cancer therapeutics. The present study sought to define synergistic antitumor benefits of concurrent HSP27-knockdown and the HSP90 inhibitor, 17-N-allylamino-17-demethoxygeldanamycin (17-AAG) or, comparatively, the non-selective kinase inhibitor, staurosporine, in GBM cells.

MATERIALS AND METHODS

Dose-response relations were determined for 17-AAG and staurosporine in three GBM cell lines. HSP27-targeted siRNA was administered alone or in combination with subtherapeutic concentrations of each drug and cells were evaluated for viability, proliferation and apoptosis.

RESULTS

Adjuvant HSP27 knockdown with 17-AAG or staurosporine produced marked and synergistic decrease in GBM cell viability and proliferation, with robust elevation of apoptotic fractions and caspase-3 activation.

CONCLUSION

HSP27 knockdown confers potent chemosensitization of GBM cells. These novel data support the development of HSP-targeting strategies and, specifically, anti-HSP27 agents for the treatment of GBM.

Neurotrophic factor expression in expandable cell populations from brain samples in living patients with Parkinson's disease

Cell-based therapies offer promise for patients with Parkinson's disease (PD); however, durable and effective transplantation substrates need to be defined. This study characterized the feasibility and growth properties of primary cultures established from small-volume brain biopsies taken during deep brain stimulation (DBS) surgery in patients with PD. The lineage and expression of neurotrophic factors with known beneficial actions in PD-affected brain circuitry were also evaluated. Nineteen patients with PD undergoing DBS surgery consented to brain biopsies prior to electrode implantation. Cultures from these samples exhibited exponential and plateau phases of growth and were readily expanded throughout multiple passages. There was robust expression of progenitor markers and the unexpected colocalization of neural and mesenchymal proteins. The oligodendrocyte transcription factor, Olig1, and the myelin-specific sphingolipid, galactocerebroside, were coexpressed with each of glial-derived neurotrophic factor, brain-derived neurotrophic factor, and cerebral dopamine neurotrophic factor. Fluorescence-activated cell sorting demonstrated homogeneous expression of both nestin and Olig1 throughout the expanded cultures. Cells remained viable after a year in cryostorage. These findings confirm the feasibility of small brain biopsies as an expandable source of autologous cell substrate in living patients and demonstrate the complex phenotype of these cells, with implications for therapeutic application in PD and other neurological diseases.

Perioperative ischemic complications of the brain after carotid endarterectomy

BACKGROUND

The potential morbidity of cerebral ischemia after carotid endarterectomy (CEA) has been recognized, but its reported incidence varies widely.

OBJECTIVE

To prospectively evaluate the development of cerebral ischemic complications in patients treated by CEA at a high-volume cerebrovascular center.

METHODS

Fifty patients with moderate or severe carotid stenosis awaiting CEA were studied with perioperative diffusion-weighted imaging of the brain and standardized neurological evaluations. Microsurgical CEA was performed by 1 of 2 vascular neurosurgeons. Radiological studies were evaluated by faculty neuroradiologists who were blinded to the details of the clinical situation.

RESULTS

Preoperative diffusion-weighted imaging studies were performed within 24 hours of surgery. A second study was obtained within 24 (92% of patients), 48 (4% of patients), or 72 (4% of patients) hours after surgery. Intraluminal shunting was used in 1 patient (2%), and patch angioplasty was used in 2 patients (4%). No patient had diffusion-weighted imaging evidence of procedure-related cerebral ischemia. Nonischemic complications consisted of postoperative confusion in an 87-year-old man with a urinary tract infection and a marginal mandibular nerve paresis in another patient. Radiological studies were normal in both patients.

CONCLUSION

CEA is a relatively safe procedure that may be performed with an acceptable risk of cerebral ischemia in select patients. The low rate of ischemic complications associated with CEA sets a standard to which other carotid revascularization techniques should be held. The current results are presented with a discussion of the senior author's preferred surgical technique and a brief review of the literature.

Lateral Transpeduncular Approach to Intrinsic Lesions of the Rostral Pons

Objective:

We describe the lateral transpeduncular approach to access lesions in the rostral pons. The surgical indications and technique are discussed in the context of an illustrative case and pertinent anatomic considerations.

Methods:

A 38-year-old man with acute right hemiparesis and bulbar symptoms had a left pontine hemorrhage with an associated cavernous malformation and venous anomaly. There was no pial or ependymal representation of the lesion. To avoid disruption of eloquent structures, the pia was entered in the posterolateral aspect of the middle cerebellar peduncle. Subsequent dissection was guided by stereotactic neuronavigation in a ventromedial trajectory along the course of the pontocerebellar fibers.

Results:

The cavernous malformation was resected completely without procedure-related morbidity. The patient’s preoperative deficits slowly improved to a functionally independent state.

Conclusion:

The lateral transpeduncular approach may be used to access intrinsic lesions of the rostral pons with relatively low morbidity. Stereotactic neuronavigation and intra-operative electrophysiological monitoring are important surgical adjuncts to guide dissection and lesion extirpation. Candidate selection, microsurgical technique, and pragmatic treatment goals remain fundamental to optimal patient outcomes.

Sustained relief of dystonia following cessation of deep brain stimulation

We describe the unusual clinical course of a patient with cranial dystonia (i.e., Meige syndrome) and additional upper limb involvement, who developed sustained relief of motor symptoms following cessation of a prolonged course of bilateral pallidal deep brain stimulation (DBS). Early response to therapy proved titratable and reversible; however, the patient gained independence from DBS in the fifth postoperative year and has since been more than a year without treatment or exacerbation of motor symptoms. Among the potential explanations for these neurological benefits lies the intriguing possibility that DBS therapy may have the capacity to induce plastic change that lessens or obviates the need for further treatment in susceptible patients.

Development of a provincial guideline for the acute assessment and management of adult and pediatric patients with head injuries

BACKGROUND

Regionalized approaches to trauma care improve patient outcomes. We developed and distributed a clinical reference poster to standardize the emergency department evaluation and management of patients with traumatic head injuries in hospitals throughout Nova Scotia.

METHODS

We conducted a MEDLINE literature search to identify publications in the fields of prehospital and emergency management of head injuries. We reviewed and collated select studies to define contemporary standards of care.

RESULTS

We derived a 3-tiered decision tool that summarizes the indications for resuscitation, radiography, specialty consultation and transfer of adult and pediatric patients with minor and major head injuries. A guideline poster was constructed and distributed to all provincial emergency departments upon approval by local trauma and critical care staff.

CONCLUSIONS

This report describes the evidence for a population-based, province-wide assessment and early management tool that was developed for health care personnel who treat patients with head traumas. Comparison of outcome data from pre- and postguideline eras will ultimately shed light on the use of regionalized approaches to managing brain injuries.

Impaired Percent Alpha Variability on Continuous Electroencephalography Is Associated with Thalamic Injury and Predicts Poor Long-Term Outcome after Human Traumatic Brain Injury

Continuous electroencephalography (cEEG) is potentially useful in determining prognosis in patients with traumatic brain injuries (TBI). The objective of this prospective, observational cohort study was to determine if the percent alpha variability (PAV) on cEEG was predictive of outcome following TBI. Injury characteristics were indexed to assess whether lesions in specific cerebral loci were correlated with PAV and patient recovery. Fifty-three TBI patients were studied using cEEG recording and serial neuroimaging. Clinical recovery was assessed at regular intervals in hospital and following discharge. The principal outcome measures included the mean 3-day PAV score, the 7-day PAV pattern, delineation of the anatomical sites of brain injury, and the 6-month clinical outcome, as measured by the Glasgow Outcome Scale (GOS). Significant univariate (p = 0.030) and multivariate (p = 0.008) relations were identified between PAV and GOS scores. PAV offered good discrimination between favorable and unfavorable 6-month outcomes (AUC 0.76) and, with a cutpoint of 0.20, had a sensitivity of 87% and negative predictive value of 82%. Multivariate modeling revealed that injuries of the thalamus (p = 0.009) and basal ganglia (p = 0.016), and the presence of diffuse edema (p = 0.009), were the key anatomical predictors of PAV. Brainstem injuries (p = 0.020) and indicators of diffuse cerebral trauma, such as deep white matter shearing (p = 0.036) and multiple subcortical lesions (p = 0.033), were the principal determinants of 6-month recovery. Inclusion of PAV enhanced the accuracy of prediction models that encompassed a selective combination of clinical and anatomical variables (adjusted R(2) = 0.458, p < 0.001). The two main results of this study are (1) PAV is a sensitive predictor of 6-month clinical outcomes following TBI, and (2) injury to the thalamus is related to impaired PAV. PAV appears best utilized as a functional adjunct to traditional clinical and anatomical predictors.

Bilateral Stimulation of the Globus Pallidus Internus to Treat Choreathetosis in Huntingtonʼs Disease: Technical Case Report

OBJECTIVE AND IMPORTANCE

Huntington's disease (HD) produces debilitating motor abnormalities that are poorly responsive to medical therapy. Deep brain stimulation (DBS) may offer a treatment option for afflicted patients, but its role in the management of HD remains unclear. In the present case, DBS leads were implanted bilaterally into the posteroventral globus pallidus internus (GPi) to control disabling and medically intractable choreathetosis in a severely affected HD patient. The surgical procedure, intraoperative electrophysiological findings, and 12-month postoperative course, with patient video, are presented.

CLINICAL PRESENTATION

This 41-year-old man with genetically confirmed HD developed motor symptoms at age 28. He had completed multiple medical trials without alleviation of his progressive and debilitating choreathetosis. Extensive clinical assessment, including neuropsychological testing, was performed to determine surgical candidacy.

INTERVENTION

DBS leads were bilaterally implanted, under stereotactic guidance, into the posteroventral GPi. Disease progression and symptom control were assessed at regular postoperative intervals. Bilateral pallidal stimulation produced a dramatic reduction in choreathetoid movements and improvement in overall motor functioning. The patient also exhibited normalization of body weight, mood, and energy level, as well as improved performance of activities of daily living. These effects were sustained at 1 year after surgery.

CONCLUSION

The clinical benefits of DBS observed in this HD patient were comparable to those reported in other hyperkinetic disorders and demonstrate that pallidal stimulation can provide long-term alleviation of HD-associated choreathetosis.

Enhanced expression of heat shock protein 27 is correlated with axonal regeneration in mature retinal ganglion cells

The small heat shock protein, Hsp27, promotes axonal regeneration in peripheral neurons; however, an analogous role in the central nervous system has not been described. This study examined the relationship between Hsp27 expression and regeneration in mature retinal ganglion cells (RGCs). Adult rat optic nerves were transected and exposed to peripheral nerve autografts to stimulate regeneration of cut RGC axons. There was a five-fold increase in the Hsp27-positive fraction of RGCs that extended new axons into the graft when compared with those that survived injury but did not regenerate (30% versus 6% respectively, P = 0.001). Hsp27 protein was located throughout somata and neuritic processes, and there was a significant positive correlation between Hsp27 expression and axonal regeneration in injured neurons (R = 0.92, P < 0.0001). These findings are consistent with the growth-associated role of Hsp27 demonstrated in peripheral neurons and suggest that Hsp27 may mediate similar physiological functions in the central nervous system.

Deep brain stimulation to treat hyperkinetic symptoms of cockayne syndrome

Cockayne syndrome manifests a spectrum of neurological dysfunction that includes medically intractable movement disorders. Deep brain stimulation has not been well studied in such rare neurodegenerative conditions. In this case, stimulation of the ventral intermediate nucleus of the thalamus was used to manage severe motor symptoms in a young man with Cockayne syndrome. There was a marked and progressive response to thalamic stimulation within weeks of surgery. These results suggest that patients with Cockayne syndrome should be considered for deep brain stimulation to treat refractory movement disorders.

Neonatal ablation of the nigrostriatal dopamine pathway does not influence limb development in rats

Hemiparkinson-hemiatrophy syndrome (HP-HA) is associated with skeletal hemiatrophy and the later development of parkinsonism. It is generally assumed that this phenotype is due to the combination of dysfunction of the basal ganglia (e.g., substantia nigra compacta and/or other related structures), causing parkinsonism, and of other areas (e.g., cerebral cortex), causing hemiatrophy. The occurrence of asymmetry of limb size in a patient with very asymmetric involvement of dopa-responsive dystonia encouraged Greene et al. (2000, Mov. Disord. 15: 537-541) to propose that lifelong deficits in nigrostriatal dopamine could account for limb asymmetry in HP-HA. The purpose of this study was to determine whether skeletal hemiatrophy could be produced in rats by unilateral, neonatal ablation of the nigrostriatal dopamine pathway. Infusion of 6-hydroxydopamine into the striatum of rat neonates resulted in loss of dopamine neurons in the ipsilateral substantia nigra, reduced striatal dopamine levels, and stimulant-induced motor asymmetry. Saline infusions neither altered the number of dopamine neurons nor produced behavioral changes. Both groups incurred discrete lesions of the ipsilateral motor cortex surrounding the infusion site and atrophy of the corresponding cerebral peduncle. Cortical, but not nigrostriatal, lesions were associated with significant atrophy of ipsilateral femora, humeri, and innominate bones, as assessed radiographically. Skeletal hemiatrophy was not observed in naive animals or in experimental animals that did not exhibit corticospinal abnormalities. The results of this study indicate that early skeletal development in rats is not affected by loss of nigrostriatal dopamine per se, but is markedly attenuated by corticospinal lesions sustained during the neonatal period.

Amphetamine-induced Fos expression is evident in gamma-aminobutyric acid neurons in the globus pallidus and entopeduncular nucleus in rats treated with intrastriatal c-fos antisense oligodeoxynucleotides

Double immunostaining for Fos and gamma-aminobutyric acid (GABA) was used in a previously established animal model of striatal dysfunction to examine whether GABA-immunoreactive neurons in the globus pallidus (GP) and entopeduncular nucleus (EP) are activated to express Fos immunoreactivity by intraperitoneal injection of amphetamine. Striatal efferent activity was suppressed by intrastriatal infusions of antisense oligodeoxynucleotide targeted to the messenger RNA of the immediate early gene, c-fos. This suppression produced robust rotational behavior and expression of Fos in the ipsilateral GP and EP following amphetamine challenge. The expression of Fos in the ipsilateral GP and EP following amphetamine challenge is not observed in naïve or control antisense-treated animals. Quantitative analysis revealed that a majority of the amphetamine-activated (Fos-immunoreactive) neurons in the GP and EP express GABA. The present results suggest that inhibitory GABAergic projection neurons within these two nuclei are regulated by inhibitory striatal output and suggests that decreased inhibitory striatal output may contribute to the motor dysfunction observed in patients with Huntington's disease.

Identification of a subpopulation of substantia nigra pars compacta gamma-aminobutyric acid neurons that is regulated by basal ganglia activity

In this report, the authors provide a novel description of a population of gamma-aminobutyric acid-containing neurons in the substantia nigra, pars compacta (SNC). By using metabolic mapping of the immediate-early gene, c-fos, the activation pattern of these cells was characterized with respect to basal ganglia stimulation. Dopaminergic stimulation with d-amphetamine or apomorphine induced Fos expression in the central region of the SNC. However, lesions of the nigrostriatal dopamine pathway significantly reduced d-amphetamine- and apomorphine-induced Fos expression in the ipsilateral and contralateral SNC, respectively. Suppression of stimulant-induced Fos expression in the striatum, using antisense oligodeoxynucleotides, also eliminated Fos expression in the ipsilateral SNC, indicating that striatal efferent projections are involved in the activation of these cells. Double-labeling immunohistochemistry revealed that the Fos-positive cells did not express tyrosine hydroxylase but were immunoreactive for glutamic acid decarboxylase. Retrograde labeling of nigrostriatal neurons, combined with Fos immunofluorescence, revealed that these Fos-positive cells did not project to the striatum. Thus, these neurons do not appear to comprise a nondopaminergic nigrostriatal circuit but likely represent locally-projecting interneurons of the substantia nigra.

Motor effects and mapping of cerebral alterations in animal models of Parkinson's and Huntington's diseases

Changes in stimulant-induced behavioral effects and subcortical c-Fos expression were compared between rodent models of Parkinson's disease (PD) and Huntington's disease (HD). Rats received either a unilateral 6-hydroxydopamine (6-OHDA)-induced lesion of the nigrostriatal dopamine pathway (PD model) or a unilateral infusion of antisense oligodeoxynucleotides targeting c-fos into the striatum (HD model). Dopamine-lesioned animals received intraperitoneal injections of either d-amphetamine (6-OHDAamp group) or apomorphine (6-OHDAapo group), whereas all animals that received antisense infusions received d-amphetamine (ASF group). All groups exhibited robust circling behavior upon stimulant challenge. Changes in subcortical activation, as assessed by the induction of Fos-like immunoreactivity (Fos-LI), were examined in several brain regions. The 6-OHDAamp and ASF groups exhibited robust, ipsiversive circling behavior, with similar changes in Fos-LI in the striatum, entopeduncular nucleus, superior colliculus, and ventromedial thalamus. The 6-OHDAapo group exhibited contraversive rotation and had reciprocal patterns of Fos-LI in these regions. Despite exhibiting the same direction of rotation, the 6-OHDAamp and ASF groups had markedly different patterns of Fos-LI in the globus pallidus and the pontine reticular formation. These results suggest that the globus pallidus may undergo distinct alterations in PD and HD and that the pontine reticular formation is particularly susceptible to changes in mesencephalic dopamine sources.

Expression of the Huntington's disease gene is regulated in astrocytes in the arcuate nucleus of the hypothalamus of postpartum rats

Huntington's disease (HD) is one of a number of neurodegenerative disorders caused by expansion of polyglutamine-encoding CAG repeats within specific genes. Huntingtin, the protein product of the HD gene, is widely expressed in neural and nonneural human and rodent tissue. The function of the wild-type or mutated form of huntingtin is currently unknown. We have observed that relative to naive and male animals, huntingtin protein was significantly increased in the arcuate nucleus of postpartum rats. Using an oligonucleotide probe, in situ and Northern blot hybridization confirmed the expression of huntingtin mRNA. Quantification of the in situ hybridization signal in the arcuate nucleus revealed an approximate sevenfold increase in the expression of huntingtin mRNA in postpartum, lactating animals compared with naive female or male animals. Emulsion autoradiography and immunohistochemistry revealed that the cells with elevated huntingtin expression had a stellate conformation that morphologically resembled astrocytes. Dual label immunofluorescence immunohistochemistry demonstrated the colocalization of huntingtin and glial fibrillary acidic protein in these cells, confirming that they were astrocytes. Astrocytes expressing huntingtin were consistently found in close apposition to neuronal soma, suggesting interactions between these cell types. During the perinatal and postnatal period, the hypothalamus undergoes alterations in metabolic function. Our results support the idea of glia-induced metabolic changes in the hypothalamus. These results provide the first demonstration of naturally occurring changes in the expression of the Huntington's disease gene in the brain and suggest that huntingtin may play an important role in the processes that regulate neuroendocrine function.

Synergistic influences of the striatum and the globus pallidus on postural and locomotor control

We have investigated the role of the globus pallidus in locomotor and postural control in a previously established animal model of striatal dysfunction. Striatal efferent activity was suppressed by intracerebral infusions of antisense oligodeoxynucleotides targeted to the messenger RNA of the proto-oncogene, c-fos. This suppression produced robust circling behavior and an atypical expression of c-fos in the ipsilateral globus pallidus following psychostimulant challenge. Simultaneous infusions of antisense oligodeoxynucleotides into both the caudate-putamen and the ipsilateral globus pallidus produced an approximate threefold increase in the intensity of rotation elicited by D-amphetamine. Excitotoxic lesioning of the globus pallidus produced marked postural asymmetry and circling behavior upon stimulation. The intensity of this rotational behavior was similar to that produced by dual infusions of antisense oligodeoxynucleotides into the caudate-putamen and the globus pallidus, and was not further potentiated by suppression of striatal c-fos expression. These results demonstrate the importance of the globus pallidus in postural and motor control, and suggest that activation of this nucleus through a reduction in striatopallidal inhibition may function to balance the output activity of the basal ganglia.

Alterations of neuronal activity in the superior colliculus of rotating animals

We have investigated the relationship between alterations in neuronal activity in the superior colliculus and behavioral responses which occur following disruption of basal ganglia circuitry. These changes were analysed following unilateral suppression of the immediate early genes, c-fos and ngfi-a, in the striatum and/or the globus pallidus. Animals with unilateral suppression of immediate early gene expression in the striatum exhibited robust circling activity, following administration of D-amphetamine, that was directed towards the side of suppression. The intensity of rotation was inversely related to the length of the recovery period following antisense infusion and increased significantly when the globus pallidus was infused simultaneously with the striatum. The difference between ipsiversive (towards the antisense-infused hemisphere) and contraversive rotations was calculated and animals were grouped by number according to their ipsiversive bias: I, <50 turns; II, 50-500 turns; III, 500-1000 turns; IV, >1000 turns. Immunohistochemical localization of Fos was used as an indicator of neuronal activity in the superior colliculus. While group I animals showed diffuse Fos-like immunoreactivity throughout the intermediate layers of the superior colliculus, those animals in groups II-IV showed increasing suppression of Fos-like immunoreactivity in the stratum album intermediale and marked enhancement in the stratum griseum intermediale. Correlation and regression analysis revealed a significant positive relationship between the number of ipsiversive rotations and the number of Fos-positive nuclei in the stratum griseum intermediale of the ipsilateral superior colliculus. These data suggest that the degree of rotation elicited in an animal may depend on reciprocal suppression/stimulation of adjacent intermediate strata of the superior colliculus. This study provides the first demonstration, using Fos immunohistochemistry, of changes in tectal activity produced by alterations in basal ganglia function. These findings support previous electrophysiological studies in this region and suggest that the nigrotectal projection may be an important site of altered basal ganglia output.

Co-administration of adenosine kinase and deaminase inhibitors produces supra-additive potentiation of N-methyl-D-aspartate-evoked adenosine formation in cortex

Activation of glutamate receptors triggers the release of adenosine, which exerts important inhibitory actions in the brain. Evoked adenosine release is potentiated when either adenosine kinase or adenosine deaminase are inhibited. We studied the effects of concurrent inhibition of adenosine kinase and adenosine deaminase on N-methyl-D-aspartate (NMDA)-evoked formation of extracellular adenosine in slices of rat parietal cortex, to determine if combinations of inhibitors of adenosine kinase and adenosine deaminase can produce supra-additive potentiation of this adenosine formation. Combinations of low concentrations of the adenosine kinase inhibitors 5'-amino-5'-deoxyadenosine (0.2 microM) or 5'-iodotubercidin (0.01 microM) with a low concentration of the adenosine deaminase inhibitor 2'-deoxycoformycin (0.2 microM) produced additive potentiations of NMDA-evoked adenosine release from slices of rat parietal cortex. However, combinations of low concentrations of 5'-amino-5'-deoxyadenosine (0.2 microM) or 5'-iodotubercidin (0.01 microM) with a maximal concentration of 2'-deoxycoformycin (200 microM) produced supra-additive potentiation of NMDA-evoked adenosine release. These findings suggest that such combinations of adenosine kinase inhibitors with adenosine deaminase inhibitors may provide useful strategies for developing therapies to treat disorders associated with excessive NMDA receptor activation, such as seizures, ischemic damage and neurodegenerative diseases.

Coordinate suppression of striatal ngfi-a and c-fos produces locomotor asymmetry and up-regulation of IEGs in the globus pallidus

We have studied the effects of inhibition of c-Fos and NGFI-A expression by intrastriatal infusion of end-capped antisense oligodeoxynucleotides to determine if their coordinate expression is conferred independently or through regulatory influences exerted between these two proteins. The previously reported locomotor bias that has been associated with unilateral c-Fos suppression was also investigated in animals receiving antisense oligodeoxynucleotides targeted to ngfi-a to determine if the behavior is specific to alterations in c-Fos expression, or if its cause may be a generalized imbalance of striatal IEGs. We show here that while unilateral suppression of c-Fos has negligible effects on NGFI-A, oligodeoxynucleotides targeted to ngfi-a markedly inhibit both NGFI-A and c-Fos expression. Animals with extensive unilateral reduction of either or both proteins demonstrated robust ipsiversive rotation when challenged with D-amphetamine. Infusions of random oligodeoxynucleotides produced neither a reduction in c-Fos or NGFI-A expression, nor a significant rotational bias following D-amphetamine challenge. Surprisingly, animals with extensive striatal IEG suppression were found to have marked up-regulation of c-Fos and NGFI-A in the ipsilateral globus pallidus, a finding which may ultimately shed light on the mechanism of antisense-induced rotational behavior.

End-capped antisense oligodeoxynucleotides effectively inhibit gene expression in vivo and offer a low-toxicity alternative to fully modified phosphorothioate oligodeoxynucleotides

Sulfur modification of oligodeoxynucleotides produces nuclease resistance but also leads to toxic effects when these compounds are administered in vivo. To assess their potential as viable alternatives to full phosphorothioate derivatives, we have used rotational behavior and immunohistochemistry to investigate the efficacy and longevity of phosphorothioate, end-capped antisense oligodeoxynucleotides in suppression of c-fos and ngfi-a in the striatum of adult rats. Our results suggest that, despite having a limited duration of action, these end-capped, chimeric oligodeoxynucleotides are capable of specifically inhibiting gene expression in vivo and may, therefore, possess broader application potential in chronic suppression models as the reduction of sulfur content is likely to greatly minimize their toxic effects.