Developmental expression and function analysis of protein tyrosine phosphatase receptor type D in oligodendrocyte myelination.

Receptor protein tyrosine phosphatases (RPTPs) are extensively expressed in the central nervous system (CNS), and have distinct spatial and temporal patterns in different cell types during development. Previous studies have demonstrated possible roles for RPTPs in axon outgrowth, guidance, and synaptogenesis. In the present study, our results revealed that protein tyrosine phosphatase, receptor type D (PTPRD) was initially expressed in mature neurons in embryonic CNS, and later in oligodendroglial cells at postnatal stages when oligodendrocytes undergo active axonal myelination process. In PTPRD mutants, oligodendrocyte differentiation was normal and a transient myelination delay occurred at early postnatal stages, indicating the contribution of PTPRD to the initiation of axonal myelination. Our results also showed that the remyelination process was not affected in the absence of PTPRD function after a cuprizone-induced demyelination in adult animals.

Cells enriched in markers of neural tissue-committed stem cells reside in the bone marrow and are mobilized into the peripheral blood following stroke.

The concept that bone marrow (BM)-derived cells participate in neural regeneration remains highly controversial and the identity of the specific cell type(s) involved remains unknown. We recently reported that the BM contains a highly mobile population of CXCR4+ cells that express mRNA for various markers of early tissue-committed stem cells (TCSCs), including neural TCSCs. Here, we report that these cells not only express neural lineage markers (beta-III-tubulin, Nestin, NeuN, and GFAP), but more importantly form neurospheres in vitro. These neural TCSCs are present in significant amounts in BM harvested from young mice but their abundance and responsiveness to gradients of motomorphogens, such as SDF-1, HGF, and LIF, decreases with age. FACS analysis, combined with analysis of neural markers at the mRNA and protein levels, revealed that these cells reside in the nonhematopoietic CXCR4+/Sca-1+/lin-/CD45 BM mononuclear cell fraction. Neural TCSCs are mobilized into the peripheral-blood following stroke and chemoattracted to the damaged neural tissue in an SDF-1-CXCR4-, HGF-c-Met-, and LIF-LIF-R-dependent manner. Based on these data, we hypothesize that the postnatal BM harbors a nonhematopoietic population of cells that express markers of neural TCSCs that may account for the beneficial effects of BM-derived cells in neural regeneration.

Intraoperative MRI for pediatric tumor management.

The emergence of intraoperative MRI has opened new doors for the surgical treatment of pediatric disorders. This technology will hopefully not only improve the surgeon's ability to obtain complete tumor resections with minimal damage to surrounding structures, but also allows surgeons to perform various procedures via less invasive measures. We performed a total of 38 procedures in 36 children in our intraoperative MRI system (GE Signa SP, open configuration). All procedures were performed within the magnet bore, which allows for either continuous real-time or periodic imaging. Procedures included craniotomy for tumor resection, open biopsy, stereotactic biopsy or catheter placement into a tumor-related cyst. There were no infectious, hemorrhagic or neurological complications. Intraoperative MRI is an useful tool for the management of pediatric neurosurgical disorders. Intraoperative imaging not only helps surgeons navigate through eloquent areas of the brain, but also ensures the maximal possible tumor resection or confirms adequate catheter placement prior to skin closure. The impact of this technology on long term survival is yet to be determined.

Vaccinia virus complement control protein modulates inflammation following spinal cord injury.

The vaccinia virus complement control protein (VCP) possesses multiple modulatory functions. Functioning as a complement inhibitory protein, VCP reduces production of proinflammatory chemotactic factors produced during complement activation. Additionally, VCP binds heparin and heparan sulfate proteoglycans, resulting in added functions shown to block monocyte chemotaxis in vitro. Using an in vivo spinal cord contusive injury model in rats, the inflammation-modulating abilities of VCP were evaluated. The results of both myeloperoxidase assaying and H&E stained section counts of spinal tissue reveal that neutrophil infiltration to the area of the lesion was reduced in animals that received VCP as compared to saline-injected controls.

Changes in cyst volume following intraoperative MRI-guided Ommaya reservoir placement for cystic craniopharyngioma.

INTRODUCTION: Intracavitary treatment of solitary cystic craniopharyngiomas with (32)P is an emerging treatment option, especially for pediatric patients. We have treated two patients with solitary cystic craniopharyngiomas using intraoperative MRI (iMRI)-guided catheter placement. METHODS: The optical tracking system of the General Electric Signa SP iMRI system was utilized for preoperative planning and intraoperative catheter tracking during insertion. Intraoperative volumetric imaging was then used to confirm final catheter position. Patients were brought back to the iMRI suite approximately 8 weeks later and diluted gadolinium was injected with further MRI to confirm the absence of communication between the cyst lumen and surrounding CSF spaces and for volumetric analysis. RESULTS: Intraoperative imaging illustrated deformation and changes in the cyst wall during catheter placement and cyst aspiration and confirmed final catheter placement. Images acquired 8 weeks following catheter placement prior to the instillation of (32)P showed decreases in cyst volume of 40 and 85%. CONCLUSION: iMRI-guided catheter placement for cystic craniopharyngiomas helps to assure successful catheter placement. Significant decreases in cyst volume occur in the interval between catheter placement and (32)P administration and must be accounted for to prevent overdosing of the radioisotope.

Development and implementation of a clinical pathway for severe traumatic brain injury.

BACKGROUND: Clinical pathways (CPs) have been shown to be beneficial in optimizing patient care and resource use. METHODS: A multidisciplinary CP for the treatment of severe traumatic brain injury (Glasgow Coma Scale score of 3-7) was developed. Data from these patients (group I) were collected prospectively and compared with a retrospective database (group II). RESULTS: There were a total of 119 patients managed in conjunction with the CP and 43 patients in the control group. No statistical differences were found between the groups in age, Glasgow Coma Scale score at 24 hours, or Injury Severity Scores. There was a significant decrease in the length of hospital stay, intensive care unit stay, and length of ventilator support in the study group (group I: 22.5, 16.8, and 11.5 days, respectively; group II: 31.0, 21.2, and 14.4 days, respectively; p < 0.03). CONCLUSION: The use of this CP helped to standardize and improve patient care with fewer complications and a potential cost savings of approximately $14,000 per patient.

Incidence rates and populations at risk for spinal cord injury: A regional study.

STUDY DESIGN: A 6 year retrospective study was conducted. OBJECTIVES: The populations at risk for spinal cord injury (SCI) in the northwestern Kentucky (KY) and southern Indiana (IN) regions were identified following examination of the causes and factors associated with SCI. SETTING: The database included patients primarily from the surrounding KY and IN counties admitted to the University of Louisville (U of L) Hospital. METHOD: Specification of SCI patient demographics, injury causes and related factors was achieved utilizing the hospital's trauma institute database and an extensive review of patient medical records. RESULTS: An adjusted average incidence rate of 27.1 cases per million per year was obtained for this region. A high rate of SCI was found for the youngest age group, 14-24 year olds, and for African Americans. A high frequency of injuries was also observed for adults between the ages of 25-39 years. Motor vehicle accidents (MVA) were the leading cause of SCI. Contributing factors included alcohol and widespread non-use of vehicle safety precautions. CONCLUSIONS: In addition to the high proportion of youth at risk for SCI, a higher proportion of older adults with SCI was observed for this region compared to other studies. Because the primary source of transportation in this area is the use of private vehicles, rather than public transportation, greater effort is warranted in emphasizing the potential risks of combining driving with alcohol consumption and non-use of seatbelts.

Development and implementation of a clinical pathway for spinal cord injuries.

The authors have developed a clinical pathway for the treatment of spinal cord injuries to help improve patient care. A clinical pathway for the treatment of patients with spinal cord injury was developed through a multidisciplinary approach. The control group (group 1) consisted of patients who were treated in the 2 years before the initiation of the pathway. Data from patients treated in conjunction with this pathway were collected prospectively (group 2). Thirty-six patients were treated in conjunction with the pathway compared with 22 in the control group. Group 2 had 6.8 fewer intensive care unit days, 11.5 fewer hospital days, 6 fewer ventilator days (p < 0.05), and a lower rate of complications. The use of a clinical care pathway for spinal cord injuries has resulted in improved patient care and fewer complications.

Treatment of neoplastic diseases of the sacrum.

Sacral neoplasms constitute a wide range of pathological entities including primary and metastatic as well as benign and malignant conditions. Often these lesions are large at the time of initial diagnosis and surgical cure may be difficult. Nonetheless, surgery may be indicated for a wide range of reasons including tissue diagnosis, palliation of pain, preservation of neurological function, or attempts for curative resection. There are numerous surgical approaches to lesions of this area which require a complete understanding of the neural, pelvic, and bony anatomy. For this reason we utilize a multidisciplinary team approach when treating these lesions. This allows for the combination of expertise from areas such as general surgery, orthopedic surgery, and neurosurgery that optimizes the treatment of these patients. In this article we review the basic techniques of diagnosis and treatment of these lesions. This overview includes the relative anatomy, symptoms, diagnosis, imaging, operative indications, surgical approaches, and potential complications.

A topical mixture for preventing, abolishing, and treating autophagia and self-mutilation in laboratory rats.

The dysesthesia and paresthesia that occurs in laboratory rats after spinal cord injury and peripheral nerve injury results in autophagia and self-mutilation. This self-destructive behavior interferes with functional assessments in designed studies and jeopardizes the health of the injured rat. We developed a topical mixture that prevents, abolishes, and treats autophagia and self-mutilation. When the mixture is applied to the limb, its bitterness effectively prevents the rat from licking and biting the limb. In addition, the mixture has antiseptic properties.

Adult human olfactory stem cells.

The location of stem cells within the adult CNS makes them impractical for surgical removal and autologous transplantation. Their limited availability and histocompatibility issues further restrict their use. In contrast, olfactory neuroepithelium (ONe) located in the nasal passageways has a continuous regenerative capability and can be biopsied readily. To investigate the potential of human ONe to provide viable populations of pluripotent cells, ONe was harvested from cadavers 6-18 h postmortem, dissociated, plated and fed every 3-4 days. Heterogeneous populations of neurons, glia, and epithelia were identified with lineage-specific markers. After several weeks, 5-10% of the cultures produced a population of rapidly dividing cells, which in turn, produced neurospheres containing at least two subpopulations based on neuronal and glial specific antigens. Most contained one or more neuronal markers; a few were positive for A2B5 and/or GFAP. To determine if growth modulators would affect the neurosphere forming cells, they were exposed to dibutyryl-cAMP. The nucleotide reduced cell division and increased process formation. Although the cells had been passaged more than 70 times, their viability remained constant as shown by the MTT viability index. Donor age or sex were not limiting factors, because neurospheres have been established from cadavers of both sexes from 50 to 95 years old at time of death. The ex vivo expansion of these cells will provide a patient-specific population of cells for immunological, genetic and pharmacological evaluation. Our long-term goal is to determine the utility of these cells to facilitate CNS repair.

Lasting paraplegia caused by loss of lumbar spinal cord interneurons in rats: no direct correlation with motor neuron loss.

OBJECT: The aims of this study were to investigate further the role played by lumbar spinal cord interneurons in the generation of locomotor activity and to develop a model of spinal cord injury suitable for testing neuron replacement strategies. METHODS: Adult rats received intraspinal injections of kainic acid (KA). Locomotion was assessed weekly for 4 weeks by using the Basso, Beattie, and Bresnahan (BBB) 21-point locomotor scale, and transcranial magnetic motor evoked potentials (MMEPs) were recorded in gastrocnemius and quadriceps muscles at 1 and 4 weeks. No changes in transcranial MMEP latency were noted following KA injection, indicating that the descending motor pathways responsible for these responses, including the alpha motor neurons, were not compromised. Rats in which KA injections included much of the L-2 segment (10 animals) showed severe locomotor deficits, with a mean BBB score of 4.5 +/- 3.6 (+/- standard deviation). Rats that received lesions rostral to the L-2 segment (four animals) were able to locomote and had a mean BBB score of 14.6 +/- 2.6. Three rats that received only one injection bilaterally centered at L-2 (three animals) had a mean BBB score of 3.2 +/- 2. Histological examination revealed variable loss of motor neurons limited to the injection site. There was no correlation between motor neuron loss and BBB score. CONCLUSIONS: Interneuron loss centered on the L-2 segment induces lasting paraplegia independent of motor neuron loss and white matter damage, supporting earlier suggestions that circuitry critical to the generator of locomotor activity (the central pattern generator) resides in this area. This injury model may prove ideal for studies of neuron replacement strategies.

The role of directly applied hypothermia in spinal cord injury.

STUDY DESIGN: The effect of intense local hypothermia was evaluated in a precision model of spinal canal narrowing and spinal cord injury in rats. The spinal cord injury was cooled with a custom cooling well used over the epidural surface. Basso, Beattie, and Bresnahan (BBB) motor scores and transcranial magnetic motor-evoked potential (tcMMEP) responses were used after injury to accurately evaluate neurologic recovery. OBJECTIVE: This study was undertaken to determine whether the prognosis for neurologic recovery in a standardized rat spinal cord injury model is altered by the direct application of precisely controlled hypothermia to the area of injury. SUMMARY OF BACKGROUND DATA: The role of hypothermia in the treatment of spinal cord injuries with neurologic deficits remains undefined. Hypothermia may decrease an area of spinal cord injury and limit secondary damage, therefore improving neurologic recovery. However, it has been difficult to consistently apply localized cooling to an area of spinal cord injury, and the use of systemic hypothermia is fraught with complications. This fact, along with the unavailability of a precise spinal cord injury model, has resulted in inconsistent results, both clinically and in the laboratory. In a rat model of spinal cord injury, 37 C and 19 C temperatures were used to study the role of hypothermia on neurologic recovery. METHODS: Male Spraque-Dawley rats (n = 52; weight, 277.7 g) were anesthetized with pentobarbital and subjected to laminectomy at T10. The rats were divided into three groups: 1) placement of a 50% spacer in the epidural space (16 rats), 2) severe (25 g/cm) spinal cord injury (16 rats), 3) 50% spacer in combination with spinal cord injury (16 rats). Eight rats in each group were tested at two temperatures: normothermic (37 C) and hypothermic (19 C). With the use of a specially designed hypothermic pool placed directly over the spinal cord for 2 hours, epidural heating to 37 C, and epidural cooling to 19 C was accomplished. Simultaneous measurements of spinal cord and body temperatures were performed. The rats underwent behavior testing using the BBB motor scores and serial tcMMEPs for 5 weeks. Statistical methods consisted of Student's t tests, one-way analysis of variance, Tukey post hoc t tests and chi2 tests. RESULTS: There was a significant improvement in motor scores in rats subjected to hypothermia compared with those that were normothermic after insertion of a 50% spacer. This improvement was observed during the 5-week duration of follow-up. In the severe spinal cord injury group and the spinal cord injury-spacer groups, no significant improvement in motor scores were obtained when the spinal cord was exposed to hypothermia. CONCLUSION: The results demonstrate that there is a statistically significant (P < 0.05) improvement in neurologic function in rats subjected to hypothermia (19 C) after insertion of a spacer that induced an ischemic spinal cord injury. This indicates that directly applied hypothermia may be beneficial in preventing injury secondary to ischemic cellular damage. The data demonstrated minimal therapeutic benefit of hypothermia (19 C) after a severe spinal cord injury.

A laryngoscope designed for intubation of the rat.

We successfully intubated 257 rats with a laryngoscope that we designed for this purpose. Orotracheal intubation with this laryngoscope can be performed quickly and without harm to the animal. This instrument provides direct visualization of the vocal cords, allowing rapid, safe intubation of the rat. Maintenance of an adequate airway with endotracheal intubation is superior to tracheostomy for repeated experiments, and therefore this laryngoscope makes such studies easier and safer to perform.

Surgical treatment of lumbar spinal stenosis in patients older than 75 years of age.

OBJECT: The purpose of this study was to evaluate the safety and efficacy of the surgical treatment of lumbar spinal stenosis in patients older than 75 years of age. METHODS: The authors reviewed the records of 65 patients with lumbar spinal stenosis who were at least 75 years of age at the time of surgery, which was performed between November 1990 and May 1996. The 65 patients (43 women, 22 men; average age 78 years) underwent a total of 71 operations (one patient underwent three, and four patients underwent two). Fifteen patients (21%) underwent isolated lumbar decompression, and 56 patients (79%) underwent decompression in conjunction with posterior spinal fusion. There was an average of 1.7 levels decompressed per isolated lumbar decompression and 2.6 levels per decompression and fusion procedure. Seven patients (10%) experienced one or more serious postoperative complication, which included wound infection, septicemia, small bowel obstruction, stroke, myocardial infarction, gastrointestinal bleeding, and pulmonary embolus. In addition there was one intraoperative complication (hypotension [1%]) that required modification of the planned surgical procedure. No deaths were documented in the perioperative period. CONCLUSIONS: With appropriate preoperative selection and evaluation, careful intraoperative monitoring, and attentive perioperative care, the surgical treatment of elderly patients with lumbar spinal stenosis can effect significant improvement with acceptable levels of morbidity and mortality.

Magnetic motor evoked potential monitoring in the rat.

OBJECT: The authors conducted a study to provide an objective electrophysiological assessment of descending motor pathways in rats, which may become a means for predicting outcome in spinal cord injury research. METHODS: Transcranial magnetic motor evoked potentials (TMMEPs) were recorded under various conditions in awake, nonanesthetized, restrained rats. Normative data were collected to determine the reproducibility of the model and to evaluate the effect of changing the stimulus intensity on the evoked signals. In addition, an experiment was performed to determine if the TMMEPs produced were the result of auditory startle response (ASR) potentials elicited by the sound generated by the movement of the copper coil inside its casing during magnetic stimulation. Transcranial magnetic motor evoked potentials were elicited after magnetic stimulation. At 100% stimulus intensity, the mean forelimb onset latency was 4.2 +/- 0.39 msec, and the amplitude was 9.16 +/- 3.44 mV. The hindlimb onset latency was 6.5 +/- 0.47 msec, and the amplitude was 11.47 +/- 5.25 mV. As the stimulus intensity was decreased, the TMMEP onset latency increased and the response amplitude decreased. The ASR potentials were shown to have longer latencies, smaller amplitudes, and were more variable than those of the TMMEPs. CONCLUSIONS: These experiments demonstrate that TMMEPs can be recorded in awake, nonanesthetized rats. The evoked signals were easy to elicit and reproduce. This paper introduces noninvasive TMMEPs as a new technique for monitoring the physiological integrity of the rat spinal cord.

The influence of spinal canal narrowing and timing of decompression on neurologic recovery after spinal cord contusion in a rat model.

STUDY DESIGN: The effect of spinal canal narrowing and the timing of decompression after a spinal cord injury were evaluated using a rat model. OBJECTIVE: To evaluate whether progressive spinal canal narrowing after a spinal cord injury results in a less favorable neurologic recovery. Additionally, to evaluate the effect of the timing of decompression after spinal cord injury on neurologic recovery. SUMMARY OF BACKGROUND DATA: Results in previous studies are contradictory about whether the amount of canal narrowing or the timing of decompression after a spinal cord injury affects the degree of neurologic recovery. METHODS: Forty adult male Sprague-Dawley rats were equally divided into a control group, in which spacers of 20%, 35%, and 50% were placed into the spinal canal after laminectomy, and an injury group in which the spacers were placed after a standardized incomplete spinal cord injury. After spacer removal, neurologic recovery in both was monitored by Basso, Beattie, Bresnahan (BBB) Locomotor Rating Scale (Ohio State University, Columbus, OH) motor scores and transcranial magnetic motor evoked potentials for 6 weeks followed by histologic examination of the spinal cords. Subsequently, 42 rats were divided into five groups in which, after spacer placement, the time until decompression was lengthened 0, 2, 6, 24, and 72 hours. Again, serial BBB motor scores and transcranial magnetic motor evoked potentials were used to assess neurologic recovery for 6 weeks until the animals were killed for histologic evaluation. RESULTS: Spacer placement alone in the control animals resulted in no neurologic injury until canal narrowing reached 50%. All of the control groups (spacer only) exhibited significantly better (P < 0.05) motor scores compared with the injury groups (injury followed by spacer insertion). Within the injury groups the motor scores were progressively lower as spacer sizes increased from the no-spacer group to the 35% group. The results in the 35% and 50% groups were not statistically different. The results of the time until decompression demonstrated that the motor scores were consistently better the shorter the duration of spacer placement (P < 0.05) for each of the time groups (0, 2, 6, 24, and 72 hours) over the 6-week recovery period. Histologic analysis showed more severe spinal cord damage as both spinal canal narrowing and the time until decompression increased. CONCLUSION: The results in this study present strong evidence that the prognosis for neurologic recovery is adversely affected by both a higher percentage of canal narrowing and a longer duration of canal narrowing after a spinal cord injury. The tolerance for spinal canal narrowing with a contused cord appears diminished, indicating that an injured spinal cord may benefit from early decompression. Additionally, it appears that the longer the spinal cord compression exists after an incomplete spinal cord injury, the worse the prognosis for neurologic recovery.

Comparing deficits following excitotoxic and contusion injuries in the thoracic and lumbar spinal cord of the adult rat.

The majority of human spinal cord injuries involve gray matter loss from the cervical or lumbar enlargements. However, the deficits that arise from gray matter damage are largely masked by the severe deficits due to associated white matter damage. We have developed a model to examine gray matter-specific deficits and therapeutic strategies that uses intraspinal injections of the excitotoxin kainic acid into the T9 and L2 regions of the spinal cord. The resulting deficits have been compared to those from standard contusion injuries at the same levels. Injuries were assessed histologically and functional deficits were determined using the Basso, Beattie, and Bresnahan (BBB) 21-point open field locomotor scale and transcranial magnetic motor evoked potentials (tcMMEPs). Kainic acid injections into T9 resulted in substantial gray matter damage; however, BBB scores and tcMMEP response latencies were not different from those of controls. In contrast, kainic acid injections into L2 resulted in paraplegia with BBB scores similar to those following contusion injuries at either T9 or L2, without affecting tcMMEP response latencies. These observations demonstrate that gray matter loss can result in significant functional deficits, including paraplegia, in the absence of a disruption of major descending pathways.

Primary culture of adult mouse olfactory receptor neurons.

Olfactory receptor neurons (ORNs) are unique because they can be replaced by stem cells throughout life. Previous studies have demonstrated that adult mouse olfactory epithelium (OE) injured by exposure to ZnSO4 through nasal irrigation can stimulate stem cell mitotic activity in situ, which continues when placed in culture. We report on an improved ZnSO4 delivery method, mist inhalation, which produces more consistent and greater yields of OE cells. Cultures established following this method contained bipolar, nest, fusiform, and giant cells. The bipolar cells usually underwent asymmetric process development. Some bipolar cells reacted positively to neuron-specific antibodies and were immunonegative for keratin and glia-specific proteins, suggesting that they were ORNs. Those that were negative for the neuron-specific proteins may represent either neuron progenitors or olfactory ensheathing cells. The fusiform cells were relatively small and undifferentiated, exposure to brain-derived neurotrophic factor resulted in their decrease and an increase in bipolar cells. Therefore, they might be the stem cells. The nest cells had morphological characteristics of epithelia and bound keratin antibodies. The giant cells had the morphology of epithelial cells but were negative for keratin; they may represent a unique cell population induced by the ZnSO4. These results indicate that the major cell types of intact OE are present in our cultures, and each retains characteristics found in situ. The mist inhalation method provides an in vitro population of adult mitotically active neurons for study.