Lentiviral vector delivery of short hairpin RNA to NG2 and neurotrophin-3 promotes locomotor recovery in injured rat spinal cord.

BACKGROUND AIMS: In this study we investigated the effect of neurotrophin-3 (NT-3) and knockdown of NG2, one of the main inhibitory chondroitin sulfate proteoglycans (CSPG), in the glial scar following spinal cord injury (SCI). METHODS: Short hairpin (sh) RNA were designed to target NG2 and were cloned into a lentiviral vector (LV). A LV was also constructed containing NT-3. LV expressing NT-3, shRNA to NG2 or combinations of both vectors were injected directly into contused rat spinal cords 1 week post-injury. Six weeks post-injection of LV, spinal cords were examined by histology for changes in scar size and by immunohistochemistry for changes in expression of CSPG, NT-3, astrocytes, neurons and microglia/macrophages. Motor function was assessed using the Basso, Beattie and Bresnahan (BBB) locomotor scale. RESULTS: Animals that received the combination treatment of LV shNG2 and LV NT-3 showed reduced scar size. These animals also showed an increase in levels of neurons and NG2, a decrease in levels of astrocytes and a significant functional recovery as assessed using the BBB locomotor scale at 2 weeks post-treatment. CONCLUSIONS: The improvement in locomotor recovery and decrease in scar size shows the potential of this gene therapy approach as a therapeutic treatment for SCI.

Hemisection spinal cord injury in rat: the value of intraoperative somatosensory evoked potential monitoring.

Techniques used to produce partial spinal cord injuries in animal models have the potential for creating variability in lesions. The amount of tissue affected may influence the functional outcomes assessed in the animals. The recording of somatosensory evoked potentials (SSEPs) may be a valuable tool for assessing the extent of lesion applied in animal models of traumatic spinal cord injury (SCI). Intraoperative tibial SSEP recordings were assessed during surgically induced lateral thoracic hemisection SCI in Sprague-Dawley rats. The transmission of SSEPs, or lack thereof, was determined and compared against the integrity of the dorsal funiculi on each side of the spinal cord upon histological sectioning. An association was found between the presence of an SSEP signal and presence of intact dorsal funiculus tissue. The relative risk is 4.50 (95% confidence interval: 1.83-11.08) for having an intact dorsal funiculus when the ipsilateral SSEP was present compared to when it was absent. Additionally, the amount of spared spinal cord tissue correlates with final functional assessments at nine weeks post injury: BBB (linear regression, R²=0.618, p<0.001) and treadmill test (linear regression, R²=0.369, p=0.016). Therefore, we propose intraoperative SSEP monitoring as a valuable tool to assess extent of lesion and reduce variability between animals in experimental studies of SCI.

Ventral "spinal epidural meningeal cysts"--not epidural and not cysts? Case series and review of the literature.

BACKGROUND: Ventral spinal epidural meningeal cysts are rare entities for which the pathogenesis is poorly understood. OBJECTIVE: We present the clinical, radiographic, surgical, and pathologic findings of 4 patients with extensive ventral spinal epidural meningeal cysts and review the relevant literature. In addition, we discuss a suspected mechanism for pathogenesis. METHODS: Four patients with anterior spinal epidural meningeal cysts are retrospectively reviewed. RESULTS: Ventral spinal epidural meningeal cysts are often large, extending on average from C2 to L1 in our series. Patients typically present with a prolonged course of symptoms and signs, including segmental muscle weakness and atrophy, subtle myelopathy, mild to moderate spinal pain, and headache. Histopathologic analysis of the cyst wall demonstrates collagenous tissue consistent with dura but without arachnoid features. Dynamic computed tomographic myelography is the study of choice for localization of the primary dural defect. Patient symptoms and neurological deficits routinely improve after appropriate surgical intervention. CONCLUSION: Diverse signs and symptoms herald the presentation of ventral spinal meningoceles. Intraoperative, radiographic, and pathological findings are all suggestive of an intradural dissection as the etiology. Hence, they may be more appropriately named "ventral spinal intradural dissecting meningoceles." Definitive treatment involves identification and obliteration of the dural defect.

Anomalous vertebral artery compression of the spinal cord at the cervicomedullary junction.

BACKGROUND: Myelopathy from ectatic vertebral artery compression of the spinal cord at the cervicomedullary junction is a rare condition. CASE DESCRIPTION: A 63-year-old female was originally diagnosed with occult hydrocephalus syndrome after presenting with symptoms of ataxia and urinary incontinence. Ventriculoperitoneal shunting induced an acute worsening of the patient's symptoms as she immediately developed a sensory myelopathy. An MR scan demonstrated multiple congenital abnormalities including cervicomedullary stenosis with anomalous vertebral artery compression of the dorsal spinal cord at the cervicomedullary junction. The patient was taken to surgery for a suboccipital craniectomy, C1-2 laminectomy, vertebral artery decompression, duraplasty, and shunt ligation. Intraoperative findings confirmed preoperative radiography with ectactic vertebral arteries deforming the dorsal aspect of the spinal cord. There were no procedural complications and at a 6-month follow-up appointment, the patient had experienced a marked improvement in her preoperative signs and symptoms. CONCLUSION: Myelopathy from ectatic vertebral artery compression at the cervicomedullary junction is a rare disorder amenable to operative neurovascular decompression.

Opticochiasmatic apoplexy in a five-year-old.

A 5-year-old female presented to the emergency department with a 24-hour history of nausea, vomiting and mental status changes. Imaging demonstrated hemorrhage from a suprasellar mass consistent with an optic nerve glioma. The patient was taken to surgery for an open biopsy and hematoma evacuation. Pathology revealed a grade 3 fibrillary astrocytoma. She was subsequently treated with carboplatin and vincristine and is now 2 years out without evidence of recurrence. Apoplexy is a rare presentation for an optic pathway glioma. To the authors' knowledge, this is the first reported case in the pediatric population. Clinical presentation appears similar to the symptoms observed in pituitary apoplexy. Timely surgery should be directed at obtaining diagnostic tissue, prevention of long-term nervous system damage and evacuation of the hematoma where feasible.

Retroviral vectors encoding ADA regulatory locus control region provide enhanced T-cell-specific transgene expression.

BACKGROUND: Murine retroviral vectors have been used in several hundred gene therapy clinical trials, but have fallen out of favor for a number of reasons. One issue is that gene expression from viral or internal promoters is highly variable and essentially unregulated. Moreover, with retroviral vectors, gene expression is usually silenced over time. Mammalian genes, in contrast, are characterized by highly regulated, precise levels of expression in both a temporal and a cell-specific manner. To ascertain if recapitulation of endogenous adenosine deaminase (ADA) expression can be achieved in a vector construct we created a new series of Moloney murine leukemia virus (MuLV) based retroviral vector that carry human regulatory elements including combinations of the ADA promoter, the ADA locus control region (LCR), ADA introns and human polyadenylation sequences in a self-inactivating vector backbone. METHODS: A MuLV-based retroviral vector with a self-inactivating (SIN) backbone, the phosphoglycerate kinase promoter (PGK) and the enhanced green fluorescent protein (eGFP), as a reporter gene, was generated. Subsequent vectors were constructed from this basic vector by deletion or addition of certain elements. The added elements that were assessed are the human ADA promoter, human ADA locus control region (LCR), introns 7, 8, and 11 from the human ADA gene, and human growth hormone polyadenylation signal. Retroviral vector particles were produced by transient three-plasmid transfection of 293T cells. Retroviral vectors encoding eGFP were titered by transducing 293A cells, and then the proportion of GFP-positive cells was determined using fluorescence-activated cell sorting (FACS). Non T-cell and T-cell lines were transduced at a multiplicity of infection (MOI) of 0.1 and the yield of eGFP transgene expression was evaluated by FACS analysis using mean fluorescent intensity (MFI) detection. RESULTS: Vectors that contained the ADA LCR were preferentially expressed in T-cell lines. Further improvements in T-cell specific gene expression were observed with the incorporation of additional cis-regulatory elements, such as a human polyadenylation signal and intron 7 from the human ADA gene. CONCLUSION: These studies suggest that the combination of an authentically regulated ADA gene in a murine retroviral vector, together with additional locus-specific regulatory refinements, will yield a vector with a safer profile and greater efficacy in terms of high-level, therapeutic, regulated gene expression for the treatment of ADA-deficient severe combined immunodeficiency.

The neurosteroid allopregnanolone promotes proliferation of rodent and human neural progenitor cells and regulates cell-cycle gene and protein expression.

Our previous research demonstrated that the neuroactive progesterone metabolite allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one) rapidly induced hippocampal neuron neurite regression (Brinton, 1994). We hypothesized that allopregnanolone-induced neurite regression was a prelude to mitogenesis initiated by a rise in intracellular calcium. Supporting this hypothesis, the current data demonstrate that allopregnanolone, in a dose-dependent manner, induces a significant increase in proliferation of neuroprogenitor cells (NPCs) derived from the rat hippocampus and human neural stem cells (hNSCs) derived from the cerebral cortex. Proliferation was determined by incorporation of bromodeoxyuridine and [3H]thymidine, fluorescence-activated cell sorter analysis of murine leukemia virus-green fluorescent protein-labeled mitotic NPCs, and total cell number counting. Allopregnanolone-induced proliferation was isomer and steroid specific, in that the stereoisomer 3beta-hydroxy-5beta-pregnan-20-one and related steroids did not increase [3H]thymidine uptake. Immunofluorescent analyses for the NPC markers nestin and Tuj1 indicated that newly formed cells were of neuronal lineage. Furthermore, microarray analysis of cell-cycle genes and real-time reverse transcription-PCR and Western blot validation revealed that allopregnanolone increased the expression of genes that promote mitosis and inhibited the expression of genes that repress cell proliferation. Allopregnanolone-induced proliferation was antagonized by the voltage-gated L-type calcium channel (VGLCC) blocker nifedipine, consistent with the finding that allopregnanolone induces a rapid increase in intracellular calcium in hippocampal neurons via a GABA type A receptor-activated VGLCC (Son et al., 2002). These data demonstrate that allopregnanolone significantly increased rat NPC and hNSC proliferation with concomitant regulation in mitotic cell-cycle genes via a VGLCC mechanism. The therapeutic potential of allopregnanolone as a neurogenic molecule is discussed.

Nystagmus testing in intoxicated individuals.

BACKGROUND: Law enforcement officers routinely conduct psychophysical tests to determine if an impaired driver may be intoxicated or in need of medical assistance. Testing includes assessment of eye movements, using the Horizontal Gaze Nystagmus (HGN) and Vertical Gaze Nystagmus (VGN) tests, which are conducted at roadside by patrol officers. These tests previously have been validated when the subject is placed in a standing posture with head upright. However, certain conditions require that the subject be tested while seated or supine. Under these conditions, Positional Alcohol Nystagmus (PAN) could be induced and mistaken for HGN or VGN. METHODS: The study was conducted at law enforcement training academy alcohol workshops in the Pacific Northwest. Ninety-six volunteer drinkers were tested when sober and three times after drinking alcohol by 40 volunteer officers experienced in administering the tests. Blood alcohol concentration (BAC) was measured objectively with a calibrated breath analysis instrument each time a subject was tested. RESULTS: The number of eye movement signs observed during the HGN test at any posture increases with increasing BAC. The presence of VGN at any test posture occurs only in the presence of signs of HGN and only at high levels of impairment. PAN was most often observed at BACs of 0.08% and higher, but was never confused with the observation of HGN or VGN, regardless of test posture. CONCLUSIONS: The HGN test administered in the standing, seated, and supine postures is able to discriminate impairment at criterion BACs of 0.08% and 0.10%. The VGN test can identify high levels of impairment at any test posture. Therefore, these tests can be used by an officer to determine if a driver is impaired, regardless of whether the driver is standing, seated, or supine.