Showing papers in "Journal of Neurotrauma in 1999"
TL;DR: Data suggest that acute administration of IL-10 reduces TNF-alpha synthesis in the spinal cord and by activated macrophages, is neuroprotective, and promotes functional recovery following SCI.
Abstract: In these studies, we examined the neuroprotective effects of the potent antiinflammatory cytokine interleukin-10 (IL-10) following spinal cord injury (SCI). Neuroprotection was assessed by...
399 citations
TL;DR: Moderate CCI in rats produces subtle MWM performance deficits accompanied by persistent alteration in M2 and VAChT immunohistochemistry and progressive tissue atrophy, which suggests a compensatory response of cholinergic neurons to increase the efficiency of ACh neurotransmission.
Abstract: Persistent cognitive deficits are one of the most important sequelae of head injury in humans. In an effort to model some of the structural and neuropharmacological changes that occur in chronic postinjury brains, we examined the longitudinal effects of moderate vertical controlled cortical impact (CCI) on place learning and memory using the Morris water maze (MWM) test, morphology, and vesicular acetylcholine (ACh) transporter (VAChT) and muscarinic receptor subtype 2 (M2) immunohistochemistry. Vertical CCI (left parietal cortex, 4 m/sec, 2.5 mm; n = 10) or craniotomy (sham) was produced in male Sprague-Dawley rats (n = 10). Place learning was tested at 2 weeks, 4 weeks, 3 months, 6 months, and 12 months postinjury with the escape platform in a different maze quadrant for each time point. At each interval, rats received 5 days of water maze acquisition (latency to find hidden platform), a probe trial to measure place memory, and 2 days of visible platform trials to control for nonspecific deficits. At 3 weeks, half the animals were sacrificed for histology. At these injury parameters, CCI produced no significant differences in place learning between injured and sham rats at 2 weeks, 4 weeks, or 6 months after injury. However, at 3 and 12 months, the injured rats took significantly longer to find the hidden platform than the sham rats. Probe trial performance differed only at 12 months postinjury between injured (25.73+/-2.1%, standard error of the mean) and sham rats (44.09+/-7.0%, p < 0.05). The maze deficits at 1 year were not due to a worsening of performance, but may have resulted from a reduced ability of injured rats to benefit from previous water maze experience. Hemispheric loss of 30.4+/-5.5 mm3 was seen at 3 weeks after injury (versus respective sham). However, hemispheric loss almost doubled by 1 year after injury (51.5+/-8.5 mm3, p < 0.05 versus all other groups). Progressive tissue loss was also reflected by a three- to fourfold increase in ipsilateral ventricular volume between 3 weeks and 1 year after injury. At 1 year after injury, immunostaining for VAChT was dramatically increased in all sectors of the hippocampus and cortex after injury. Muscarinic receptor subtype 2 (M2) immunoreactivity was dramatically decreased in the ipsilateral hippocampus. This suggests a compensatory response of cholinergic neurons to increase the efficiency of ACh neurotransmission. Moderate CCI in rats produces subtle MWM performance deficits accompanied by persistent alteration in M2 and VAChT immunohistochemistry and progressive tissue atrophy. The inability of injured rats to benefit from repeated exposures to the MWM may represent a deficit in procedural memory that is independent of changes in hippocampal cholinergic systems.
288 citations
TL;DR: Amelioration of cortical damage with CsA indicates that pharmacological therapies can be devised that will significantly alter neurological outcome after injury and suggest that the mechanisms responsible for tissue necrosis following TBI are amenable to manipulation.
Abstract: Experimental traumatic brain injury (TBI) results in a rapid and significant necrosis of cortical tissue at the site of injury. In the ensuing hours and days, secondary injury exacerbates the original damage, resulting in significant neurological dysfunction. Young adult animals were treated either 5 min before or immediately after a cortical injury with the immunosuppressant cyclosporin A (CsA). All animals treated with CsA demonstrated a significant reduction in the amount of cortical damage 7 days following TBI. The effect was observed in adult rats and in two different strains of adult mice following systemic administration of the drug. Cyclosporin A has known effects on mitochondria by inhibiting the opening of the permeability transition pore and maintaining calcium homeostasis. These results with a clinically approved drug demonstrate an almost 50% reduction in lesion volume and suggest that the mechanisms responsible for tissue necrosis following TBI are amenable to manipulation. Since Cs...
237 citations
TL;DR: The results once again suggest that the maintenance of the functional integrity of the mitochondria can prevent TAI, presumably via the preservation of the local energy homeostasis of the axon.
Abstract: Recent observations concerning presumed calcium-induced mitochondrial damage and focal intraaxonal proteolysis in the pathogenesis of traumatic axonal injury (TAI) have opened new perspect...
203 citations
TL;DR: It is suggested that sacral spinal rats develop symptoms of spasticity in tail muscles with similar characteristics to those seen in limb muscles of humans with spinal cord injury, and thus provide a convenient preparation for studying this condition.
Abstract: We have investigated sacral spinal cord lesions in rats with the goal of developing a rat model of muscular spasticity that is minimally disruptive, not interfering with bladder, bowel, or hindlimb locomotor function. Spinal transections were made at the S2 sacral level and, thus, only affected the tail musculature. After spinal transection, the muscles of the tail were inactive for 2 weeks. Following this initial period, hypertonia, hyperreflexia, and clonus developed in the tail, and grew more pronounced with time. These changes were assessed in the awake rat, since the tail is readily accessible and easy to manipulate. Muscle stretch or cutaneous stimulation of the tail produced muscle spasms and marked increases in muscle tone, as measured with force and electromyographic recordings. When the tail was unconstrained, spontaneous or reflex induced flexor and extensor spasms coiled the tail. Movement during the spasms often triggered clonus in the end of the tail. The tail hair and skin were extremely hyperreflexive to light touch, withdrawing quickly at contact, and at times clonus could be entrained by repeated contact of the tail on a surface. Segmental tail muscle reflexes, e.g., Hoffman reflexes (H-reflexes), were measured before and after spinalization, and increased significantly 2 weeks after transection. These results suggest that sacral spinal rats develop symptoms of spasticity in tail muscles with similar characteristics to those seen in limb muscles of humans with spinal cord injury, and thus provide a convenient preparation for studying this condition.
197 citations
TL;DR: The cytokine suppression found in the hypothermic group continued even after rewarming in these patients showing an improved clinical course, but not in those whose condition worsened, suggesting the need for further prospective randomized studies to examine the role of cytokine suppressed in the beneficial effects of moderate hypothermia.
Abstract: Moderate hypothermia may reduce subsequent neuronal damage after traumatic brain injury. Interleukin (IL)-6 may have a role in the pathogenesis of traumatic neuronal damage or repair. Using the enzyme-linked immunological sorbent assay (ELISA), we serially measured IL-6 levels in plasma obtained from the radial artery (systemic) and internal jugular vein (regional) in 13 cerebral trauma patients who underwent hypothermia of 32-33 degrees C ranged from 4-9 days postinjury and 10 head-injured patients who were maintained at normothermic levels (36-37 degrees C). In both patient populations, surface cooling was used since even in the normothermic group, cooling was needed to maintain patient temperature in the normothermic range. All patients were mechanically ventilated after injection of midazolam and vecuronium. The administration of these agents were continued until the end of the study. Hypothermia was typically maintained for four days, however, in some cases based upon CT findings and/or intra-cranial pressure change, the duration was prolonged. No significant differences were found between the two groups in age, gender and Glasgow Coma Scale upon admission. Further, no differences were found in terms of the classification of computed tomography findings or the occurrence of pupillary abnormalities on admission. The patients in this study had not sustained either abdominal or thoracic trauma. Before inducing hypothermia, IL-6 levels in the arterial and internal jugular venous blood exceeded the normal range. Specifically, the internal jugular plasma levels were significantly higher than those in the arterial plasma. While IL-6 levels in the normothermic group did not decrease even at 4 days postinjury, the plasma cytokine levels fell at both sites sharply after moderate hypothermia. The cytokine suppression found in the hypothermic group continued even after rewarming in these patients showing an improved clinical course, but not in those whose condition worsened. In addition to these changes in cytokine levels, the Glasgow Outcome Scale at 6 months postinjury was significantly higher in the hypothermic group than in the normothermia group. Based on the above, this clinical study with its small patient sample size suggests the need for further prospective randomized studies to examine the role of cytokine suppression in the beneficial effects of moderate hypothermia in patients with traumatic brain injury.
191 citations
TL;DR: It is suggested that LB therapy may be generally applied in the motor rehabilitation of persons with acute and chronic incomplete paraplegia and tetraplegia, and its use in other diseases is discussed.
Abstract: Recent reports indicate that intensive training of upright walking on a treadmill (German: Laufband, LB) according to the “rules of spinal locomotion”, significantly improves walking capability in spinal cord damaged persons. The aids provided initially are body weight support by a harness and proper placing of one or both limbs by therapists.
156 citations
TL;DR: In this article, the authors investigated the regional and temporal distribution of activated NF-kappaB in rats at 1 h, 2 h, 24 h, 48 h, 1 week, 2 weeks, 1 month, 2 months, 6 months, and 1 year following brain injury in rats.
Abstract: Activation of transcription factor, nuclear factor kappa B (NF-kappaB), has been shown to play a key role in inflammatory response, neuronal survival and signaling. We investigated the regional and temporal distribution of activated NF-kappaB in rats at 1 h, 2 h, 24 h, 48 h, 1 week, 2 weeks, 1 month, 2 months, 6 months, and 1 year following brain injury in rats. Early after trauma (1-2 h), activated NF-kappaB was detected in axons, and subsequently found in the cytoplasm and nucleus of neurons by 24 h and lasting up to 1 week. In addition, by 24 h posttrauma, activated NF-kappaB was detected in microglia/macrophages and astrocytes in injured cortex. Surprisingly, this activation persisted for at least 1 year following injury in the cortex, primarily at the margins of progressively enlarging ventricle. Activated NF-kappaB was also detected in endothelial cells, as early as 1 h, and persisted for up to 1 year. These results suggest that a neuronal response to brain trauma includes the activation of NF-kappaB first in the axon with subsequent translocation to the nucleus. Furthermore, these results demonstrate that remarkably prolonged activation of NF-kappaB in glia is found in the same regions undergoing persistent atrophy, suggesting NF-kappaB activation may play a role in long-term inflammatory processes following brain trauma.
155 citations
TL;DR: Levels of TGF-beta could not be correlated with extent of initial injury by computed tomography (CT), CD4/CD8 ratios, acute lung injury, or clinical outcome as rated by the Glasgow Outcome Scale (GOS).
Abstract: Traumatic brain injury (TBI) induces local and systemic immunologic changes, release of cytokines, and cell activation. Perpetuation of these cascades may contribute to secondary damage to the brain. Therefore, the ability of the antiinflammatory mediator transforming growth factor-beta (TGF-β) to downregulate intrathecal immunoactivation may be of fundamental value for diminishing the incidence and extent of secondary insults. In this study, the release of TGF-β into cerebrospinal fluid (CSF) and serum of 22 patients with severe TBI was analyzed with respect to the function of the blood-brain barrier (BBB) for 21 days. Levels of TGF-β in CSF increased to their maximum on the first day (median, 1.26 ng/mL), thereafter decreasing gradually over time. Median TGF-β values in serum always remained within the reference interval (6.5 to 71.5 ng/mL). Daily assessment of the CSF-serum albumin quotient (QA) and of the CSF-serum TGF-β quotient (QTGF-β) showed a strong correlation between maximal QTGF-β and...
133 citations
TL;DR: It is shown that an applied electric field in which the polarity is reversed every 15 minutes can improve the outcome from severe, acute spinal cord injury in dogs.
Abstract: We show that an applied electric field in which the polarity is reversed every 15 minutes can improve the outcome from severe, acute spinal cord injury in dogs. This study utilized naturally injured, neurologically complete paraplegic dogs as a model for human spinal cord injury. The recovery of paraplegic dogs treated with oscillating electric field stimulation (OFS) (approximately 500 to 600 microV/mm; n = 20) was compared with that of sham-treated animals (n = 14). Active and sham stimulators were fabricated in West Lafayette, Indiana. They were coded, randomized, sterilized, and packaged in Warsaw, Indiana, and returned to Purdue University for blinded surgical implantation. The stimulators were of a previously unpublished design and meet the requirements for phase I human clinical testing. All dogs were treated within 18 days of the onset of paraplegia. During the experimental applications, all received the highest standard of conventional management, including surgical decompression, spinal stabilization (if required), and acute administration of methylprednisolone sodium succinate. A radiologic and neurologic examination was performed on every dog entering the study, the latter consisting of standard reflex testing, urologic tests, urodynamic testing, tests for deep and superficial pain appreciation, proprioceptive placing of the hind limbs, ambulation, and evoked potential testing. Dogs were evaluated before and after surgery and at 6 weeks and 6 months after surgery. A greater proportion of experimentally treated dogs than of sham-treated animals showed improvement in every category of functional evaluation at both the 6-week and 6-month recheck, with no reverse trend. Statistical significance was not reached in comparisons of some individual categories of functional evaluation between sham-treated and OFS-treated dogs (ambulation, proprioceptive placing); an early trend towards significance was shown in others (deep pain), and significance was reached in evaluations of superficial pain appreciation. An average of all individual scores for all categories of blinded behavioral evaluation (combined neurologic score) was used to compare group outcomes. At the 6-month recheck period, the combined neurologic score of OFS-treated dogs was significantly better than that of control dogs (p = 0.047; Mann-Whitney, two-tailed).
127 citations
TL;DR: The authors believe they have tapped into a mechanism that underlies a remarkable degree of natural plasticity programmed into the nervous system at the cellular level, and they have now exploited those properties for therapeutic ends.
Abstract: Multipotent neural progenitors and stem cells may integrate appropriately into the developing and degenerating central nervous system. They may also be effective in the replacement of genes, cells, and nondiffusible factors in either a widespread or a more circumscribed manner, depending on the therapeutic demands of the clinical situation. In addition, they may be uniquely responsive to some types of neurodegenerative conditions. We believe that these various appealing capabilities are the normal expression of basic biologic properties and attributes of a stem cell. The therapeutic utility of some of those properties is illustrated in this review of ongoing work in our laboratory, particularly with regard to spinal dysfunction. In these examples, we believe we have tapped into a mechanism that underlies a remarkable degree of natural plasticity programmed into the nervous system at the cellular level, and we have now exploited those properties for therapeutic ends.
TL;DR: It is shown that the embryonic human brain contains multipotent central nervous system (CNS) stem cells, which may provide a continuous, standardized source of human neurons that could virtually eliminate the use of primary human fetal brain tissue for intracerebral transplantation.
Abstract: In this work, we show that the embryonic human brain contains multipotent central nervous system (CNS) stem cells, which may provide a continuous, standardized source of human neurons that could virtually eliminate the use of primary human fetal brain tissue for intracerebral transplantation. Multipotential stem cells can be isolated from the developing human CNS in a reproducible fashion and can be exponentially expanded for longer than 2 years. This allows for the establishment of continuous, nontransformed neural cell lines, which can be frozen and banked. By clonal analysis, reverse transcription polymerase chain reaction, and electrophysiological assay, we found that over such long-term culturing these cells retain both multipotentiality and an unchanged capacity for the generation of neuronal cells, and that they can be induced to differentiate into catechlaminergic neurons. Finally, when transplanted into the brain of adult rodents immunosuppressed by cyclosporin A, human CNS stem cells migrate away from the site of injection and differentiate into neurons and astrocytes. No tumor formation was ever observed. Aside from depending on scarce human neural fetal tissue, the use of human embryonic CNS stem cells for clinical neural transplantation should provide a reliable solution to some of the major problems that pertain to this field, and should allow determination of the safety characteristics of the donor cells in terms of tumorigenicity, viability, sterility, and antigenic compatibility far in advance of the scheduled day of surgery.
TL;DR: Investigation of the temporal and spatial profiles of apoptotic cells in an experimental transection spinal cord injury by the TUNEL method suggests that oligodendrocytes may be "trapped" within rapidly swollen and disintegrating myelin lamellae, which isolates and perhaps predisposes them to death.
Abstract: We have investigated the temporal and spatial profiles of apoptotic cells in an experimental transection spinal cord injury by the terminal deoxynucleotidyl transferase-mediated biotin-16-2'-deoxyuridine-5'-triphosphate nick-end labeling (TUNEL) method. Twenty-four hours postinjury, a numerous TUNEL-positive cells appeared both rostrally and caudally to the transection site. Those positive cells, however, gradually diminished in number by several days postinjury. In contrast, other TUNEL-positive cells were found scattered within the white matter remote from the lesion by the third day postinjury. These cells were typically embedded in or among vacuolated fibers, where they were identified in close proximity to the vacuolated space enclosed by myelin basic protein (MBP)-positive structures confirmed by TUNEL-MBP double staining. Because of their linear arrangement, these TUNEL-positive cells were considered interfascicular oligodendrocytes, a fact that was confirmed by the finding that some TUNEL-positive cells were also stained with CCI, a cell marker for oligodendrocyte. Electron microscopic studies revealed that the cells expressing apoptotic morphology were invariably encased in a space formed by myelin splitting. Although the biological significance of apoptotic interfascicular oligodendrocytes in the process of wallerian degeneration is yet to be determined, the finding of such profiles localized within degenerating myelin structures suggests that; oligodendrocytes may be "trapped" within rapidly swollen and disintegrating myelin lamellae, which isolates and perhaps predisposes them to death.
TL;DR: Intathecal infusion of exogenous bFGF following SCI significantly reduces tissue damage and enhances functional recovery and Astrocyte and microglial reactivity was more pronounced in bF GF-treated animals versus controls.
Abstract: The rapid increase in basic fibroblast growth factor (bFGF) production following spinal cord injury (SCI) in rats is thought to serve a role in the cellular processes responsible for the f
TL;DR: The results demonstrate that following human blunt head injury, there is a significant degradation of neurofilament proteins and increased levels of calpain-mediated spectrin breakdown products within the corpus callosum, which supports the hypothesis that cal pain-mediated breakdown of the cytoskeleton may contribute to axonal damage after head injury.
Abstract: Calpain-mediated breakdown of the cytoskeleton has been proposed to contribute to brain damage resulting from head injury. We examined the corpus callosum from patients who died after a bl...
TL;DR: The consistent positive trends seen in ICP, TIL, neuropsychological tests, and, most importantly, 3- and 6-month GOS provide supportive evidence that a bradykinin antagonist may play a neuroprotective role in severe brain injury.
Abstract: A phase II prospective, randomized, double blind clinical trial of Bradycor™, a bradykinin antagonist, was conducted at 31 centers within North America in severely brain injured patients. Patients of Glasgow Coma Score (GCS) 3–8 (n = 139) with at least one reactive pupil were randomized to receive either Bradycor, 3 μg/kg/min or placebo as a continuous intravenous infusion for 5 days, with the infusion beginning within 12 h of the injury. The primary objective was to assess the efficacy of a continuous infusion of Bradycor (3.0 mc/kg/min) in preventing elevation of intracranial pressure (ICP). Other efficacy measures included the effect of Bradycor on the Therapy Intensity Level (TIL), mortality, and functional outcome. A secondary objective was to evaluate the safety of Bradycor in patients with severe brain injury. Randomization was carried out according to a computer generated randomization list. Patients were followed for the first 14 days of hospitalization with long-term outcome assessed at...
TL;DR: The results suggest that background strain should be carefully considered with experiments involving genetically altered mice, especially when planning behavioral outcome measures after CNS injury.
Abstract: Recent studies have suggested that mouse models of traumatic brain injury may be useful for evaluating the role of single gene products in brain trauma. In the present study, we report that three background strains (C57BL/6, FVB/N, and 129/SvEMS), commonly used in genetically altered mice, exhibit significantly different behavioral responses when subjected to sham surgery (n = 9 per group) or moderate controlled cortical impact (CCI) injury (n = 12 per group). Injured animals from all three strains showed delayed recovery of pedal withdrawal and righting reflexes compared to sham-operated controls. Significant deficits in both a forepaw contraflexion and rotarod task were evident for up to 7 days after injury, with no significant difference among strains. Sham-operated C57BL/6 mice performed significantly better than FVB/N and 129/SvEMS sham controls in a beam walking task up to 4 weeks after surgery. However, CCI-injured FVB/N mice outperformed injured animals from both other strains in this same task. Significant impairment of place learning in the Morris water maze and Barnes circular maze was observed at 7-10 days and 21-24 days after injury, respectively, in C57BL/6 mice when compared with sham controls. Sham-operated FVB/N and 129/SvEMS mice were unable to learn either task, and performance did not differ significantly from respective CCI injured animals. Our results suggest that background strain should be carefully considered with experiments involving genetically altered mice, especially when planning behavioral outcome measures after CNS injury.
TL;DR: The premise that biochemical changes (primarily lipid peroxidation) are not caused by secondary ischemic-hypoxic phenomena but rather are triggered by these forces acting on the brain at the time of impact is strongly supported.
Abstract: The effect of mild closed head trauma, induced by the weight-drop method (450 g from a 1-m height), on lipid peroxidation and energy metabolism of brain tissue was determined at various times after cerebral injury in spontaneously breathing rats (1, 10, 30 minutes and 2, 6, 15, 24, 48, and 120 hours) Animals were continuously monitored for the evaluation of blood pressure, blood gases, heart rate, and intracranial pressure Analysis of malondialdehyde (MDA) as an index of lipid peroxidation, ascorbic acid, high-energy phosphates, nicotinic coenzymes, oxypurines, and nucleosides was performed by high-performance liquid chromatography (HPLC) on neutralized perchloric acid extract of the whole brain Data showed that MDA, undetectable in control, sham-operated rats, was already present within 1 minute of trauma (177 nmol/g wet weight; SD = 029) and reached maximal values by 2 hours (7226 nmol/g ww; SD = 1126), showing a progressive slow decrease thereafter In contrast, ATP, GTP, and nicotinic coenzyme (NAD and NADP) concentrations showed significant reduction only by the second hour postinjury Maximal decrease of the ATP and GTP concentrations were seen at 6 hours postinjury, whereas NAD and NADP concentrations showed maximum decline by 15 hours Values recorded in mechanically ventilated rats did not differ significantly from those obtained in spontaneously breathing animals These findings, supported by the absence of blood gas and blood pressure changes in the spontaneously breathing rats, strongly support the premise that biochemical changes (primarily lipid peroxidation) are not caused by secondary ischemic-hypoxic phenomena but rather are triggered by these forces acting on the brain at the time of impact In addition, these results suggest that depression of energy metabolism might be caused by peroxidation of the mitochondrial membrane with a consequent alteration of the main mitochondrial function-that is, the energy supply
TL;DR: It is indicated that NAC administered postinjury at an early stage can effectively restore TBI-induced mitochondrial dysfunction and the protective effect of NAC may be related to its restoration of GSH levels in the brain.
Abstract: Efficacy of N-acetylcysteine (NAC) in traumatic brain injury (TBI)-induced mitochondrial dysfunction was evaluated following controlled cortical impact injury in rats. Respiratory function and calcium transport of rat forebrain mitochondria from injured and uninjured hemispheres were examined. NAC significantly restored mitochondrial electron transfer, energy coupling capacity, calcium uptake activity and reduced calcium content absorbed to brain mitochondrial membranes when examined 12 h post-TBI if NAC was administered i.p. 5 min before injury or 30 min or 1 h postinjury. Glutathione (reduced form, GSH) levels in brain tissues were decreased at all time points examined over a 14-day observation period, while mitochondrial GSH levels significantly decreased only at 3 days and 14 days following TBI. NAC treatment given within 1 h greatly restored brain GSH levels from 1 h to 14 days and mitochondrial GSH levels from 12 h to 14 days post-TBI. NAC did not show protective effects when given 2 h postinjury. Our data indicate that NAC administered postinjury at an early stage can effectively restore TBI-induced mitochondrial dysfunction and the protective effect of NAC may be related to its restoration of GSH levels in the brain.
TL;DR: Evidence is provided that necrosis and apoptosis follow a distinctly different time course after partial optic nerve injury.
Abstract: We have investigated time course and characteristics of retinal ganglion cell (RGC) death after partial optic nerve injury. In situ end labeling of DNA fragments with the terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine (dUTP)-biotin nick end labeling (TUNEL) method revealed the presence of apoptotic cells on as early as 5 days postcrush with a very high number of TUNEL-positive cells 1 week postinjury. At the ultrastructural level, features of apoptosis were clearly present in the ganglion cell layer at this time point. Moreover, TUNEL-positive cells could be identified as retinal ganglion cells by retrograde labeling with fluorogold. In addition, DNA laddering characteristic for apoptosis was found 1 week postinjury. A considerable number of TUNEL-labeled cells was still found after 2 weeks postinjury. Retinal whole mounts prepared at postlesion days 2-5, however, revealed that many cell bodies with ruptured membranes as evidenced by nucleosomal Sytox staining were present. These cells were also identified as retinal ganglion cells by retrograde labeling with fluorogold. Moreover, at this early stages of RGC degeneration necrotic cellular profiles could be detected by electron microscopic analysis. Thus, evidence is provided that necrosis and apoptosis follow a distinctly different time course after partial optic nerve injury.
TL;DR: The conclusion that some severed and subsequently PEG-fused spinal axons both demonstrate restored anatomical continuity and also are physiologically competent to conduct action potentials is supported.
Abstract: We describe a technique using the water-soluble polymer polyethylene glycol (PEG) to reconnect the two segments of completely transected mammalian spinal axons within minutes. This was accomplished by fusing completely severed strips of isolated guinea pig thoracic white matter maintained in vitro in a double sucrose gap recording chamber. The faces of the severed segments were pressed together, and PEG (MW 1,400-3,500 d; approximately 50% by weight in distilled water) was applied directly to this region through a micropipette and removed by aspiration within 2 min. Successful fusion was documented by the immediate restored conduction of compound action potentials through the original transection and by the variable numbers of fused axons in which anatomical continuity was shown to be restored by high-resolution light microscopy and by the diffusion of intracellular fluorescent dyes through fused axons. These data support the conclusion that some severed and subsequently PEG-fused spinal axons both demonstrate restored anatomical continuity and also are physiologically competent to conduct action potentials. This work adds to our previous demonstration that PEG application can immediately repair severely crushed, rather than cut, spinal cord white matter, and may lead to novel treatments for acute trauma to the central and peripheral nervous systems.
TL;DR: It is demonstrated that the continuous intramedullary infusion of bFGF initiated one hour after moderate contusion injury of the spinal cord significantly reduces the total zone of injury and the zone of partial preservation.
Abstract: Cytokines and neurotrophic factors have been implicated in the pathophysiology of injury to the central nervous system. While some cytokines are considered pro-inflammatory, other factors promote neuronal growth and survival. The present study investigated the neuroprotective effects of interleukins 1 (IL-1), 4 (IL-4), and 6 (IL-6), nerve growth factor (NGF), ciliary neurotrophic factor (CNTF), and basic fibroblast growth factor (bFGF) in a contusion model of spinal cord injury. Female Sprague-Dawley rats (n = 55) sustained a 10-g weight-drop injury to the lower thoracic spinal cord (T10) from a height of 12.5 mm using the NYU impactor. A micro-infusion system (Alzet minipump) was used to continuously deliver drugs or vehicle directly into the epicenter of the contused spinal cord starting 1 or three h postinjury. At the end of 7 days, animals were perfused and the cords removed for histopathological analysis. Longitudinal serial sections were cut on a freezing microtome and stained with cresyl v...
TL;DR: Hyperemia may not be as common in severe pediatric head injury as previously thought and there is no reason to treat children differently from adults, according to a better understanding of the pathophysiology of severe pediatricHead injury.
Abstract: Diffuse cerebral swelling is a frequent finding after severe pediatric head injury, and is two to five times as common in children as in adults. Hyperemia or cerebrovascular engorgement has long been considered by many as the cause of diffuse swelling and raised intracranial pressure (ICP). Consequently, reduction of the vascular compartment by institution of hyperventilation and avoidance of mannitol has been advocated for the intensive care management of severely head-injured children. Suzuki and colleagues (1990) studied cerebral blood flow (CBF) in 80 normal, unanesthetized children. It was shown that CBF in normal children may range from 40 mL/100 g per minute during the first 6 months of life to a peak of 108 mL/100 g per minute at age 3 to 4 years, and down to 71 mL/100 g per minute after age 9 years. Considering this large range, comparisons of CBF data in children are valid only when small, well-defined age ranges are selected. When the CBF values of children with severe head injuries (described in previous research) were compared with normal values in children, there did not seem to be a substantial increase of CBF. Hyperemia may therefore not be as common in severe pediatric head injury as previously thought. Until we acquire a better understanding of the pathophysiology of severe pediatric head injury, and what the optimal treatment in children would be, there is no reason to treat children differently from adults.
TL;DR: Observations indicate microglia have at least two different spatial and temporal patterns of activation, one of which accompanies Wallerian degeneration and is independent of the blood-borne complement activating system.
Abstract: This study sought to experimentally clarify time-dependent, differential microglial activation at various spinal cord locations in response to injury. The spinal cords of Wistar rats were either sharply transected at the Th 11 or subjected to compression at the same site. Immediately to 4 weeks after injury, each spinal cord was fixed and cut into longitudinal frozen sections, and was immunostained with OX42 for resident and activated microglia, OX-6 for activated microglia, GFAP for activated astrocytes, and biotinylated BS-I, a lectin for both resident and activated microglia. From three to 24 hours after injury, we observed a narrow belt around the transection site in which OX42 positive microglia were dramatically reduced in number, or often absent. BS-I labeling of the zone disclosed the rapid transformation of those microglia possessing typical antler-like processes to macrophage-like cells. At day 1 and thereafter, the zone of reduced OX42 immunoreactivity was gradually replaced by macrophage-like OX42-positive round cells, and the lesion itself was ultimately capped by fibrogliotic scar tissue. By 2-4 weeks postinjury, another phase of microglial activation was observed in those white matter tracts undergoing Wallerian degeneration. These microglia characterized by the presence of newly-expressed MHC class II antigens. We posit that the decreased OX42 immunoreactivity suggests that CR3 is quickly saturated by activated iC3b and internalized, but not down-regulated. The trigger for this transformation most likely occurs through signaling by iC3b-saturated CR3. In contrast, microglia activation along those degenerating tracts undergoing Wallerian degeneration does not appear to be CR3-related, as the CR3 is upregulated. These observations indicate microglia have at least two different spatial and temporal patterns of activation. One is rapid and most likely involves the blood-borne complement activating system. The other accompanies Wallerian degeneration and is independent of the blood-borne complement system.
TL;DR: It is confirmed that hypothermia provides remarkable protection against the adverse effects of neuronal damage exacerbated by secondary injury, and neuronal damage was equal to that of the trauma alone group (p = 0.42).
Abstract: It is well established in mechanical head trauma that posttraumatic secondary insults, such as hypoxia and hypotension exacerbate neuronal injury and lead to worse outcome. In this study, the neuroprotective effect of hypothermia on the reduction of supraventricular subcortical neuronal damage was evaluated using an impact-acceleration model of diffuse traumatic brain injury coupled with both moderate and severe periods of hypoxia and hypotension. A total of 135 adult male Sprague-Dawley rats (340-375 g) were divided into three experimental studies: (I) physiological evaluation (n = 36); (II) quantitative analysis of the effect of trauma coupled with moderate and severe hypotension on neuronal damage assessed at 4 (n = 39) and 24 h (n = 24); and (III) the neuroprotective effect of hypothermia following moderate secondary insult (n = 36). Induction of hypothermia occurred at 15 min postinjury, to a level of 30 degrees C for 60 min. At the designated time points (4 and 24 h), the animals were sacrificed via standard transcardial perfusion techniques for histological processing. Quantitative assessment of neuronal damage using routine HE however, there was a remarkable increase in the neuronal damage of the THH-10 group (29.88 50 +/- 8.20/hpf). However, hypothermia provided nearly complete protection against secondary insults, and neuronal damage was equal to that of the trauma alone group (p = 0.42). The results of this study confirm that hypothermia provides remarkable protection against the adverse effects of neuronal damage exacerbated by secondary injury. This study also presents a new model of secondary insult, which can be used experimentally to further define the mechanism of increased vulnerability of the injured brain.
TL;DR: Results provide evidence that small variations of brain temperature modify glutamate excitotoxicity and suggest that the change in glutamate diffusion in the extracellular space is one mechanism by which mild hypothermia and hyperthermia exert their protective and harmful effects respectively.
Abstract: The purpose of this study was to examine the effects of mild hypothermia and hyperthermia on glutamate excitotoxicity. Glutamate-induced cortical lesions were produced in hypothermic (32°C), normothermic (37°C), and hyperthermic (40°C) rats by perfusion of a 0.5 M glutamate solution via a microdialysis probe. The volume of the lesion 7 days after glutamate perfusion was quantified histologically by image analysis. This histological assessment was performed in two experiments; in one, each of the target temperatures was induced before glutamate perfusion, and in the other, each of the target temperatures was induced after stopping the glutamate perfusion. We also examined the effect of temperature on the diffusion of exogenously delivered material in the extracellular space using autoradiography of the perfused glutamate solution containing 14C-Iabeled sucrose. In the two experiments in which each of the target temperatures was induced before or after glutamate perfusion, the volume of damage was ...
TL;DR: The whole body appeared to be under oxidative stress, within 24 h after brain injury, according to dynamic changes in LMWA levels, which indicate that the whole body responds to CHI.
Abstract: Traumatic injury to the brain triggers the accumulation of harmful mediators, including highly toxic reactive oxygen species (ROS). Endogenous defense mechanism against ROS is provided by low molecular weight antioxidants (LMWA), reflected in the reducing power of the tissue, which can be measured by cyclic voltammetry (CV). CV records biological peak potential (type of scavenger), and anodic current intensity (scavenger concentration). The effect of closed head injury (CHI) on the reducing power of various organs was studied. Water and lipid soluble extracts were prepared from the brain, heart, lung, kidney, intestine, skin, and liver of control and traumatized rats (1 and 24 h after injury) and total LMWA was determined. Ascorbic acid, uric acid, α-tocopherol, carotene and ubiquinol-10 were also identified by HPLC. The dynamic changes in LMWA levels indicate that the whole body responds to CHI. For example, transient reduction in LMWA (p < 0.01) in the heart, kidney, lung and liver at 1 h sugge...
TL;DR: The outcome was significantly better in the patients with a good or partial ICP response to pentobarbital, with 21% of these patients having a good recovery or moderate disability at 3 months after injury, compared with 100% persistent vegetative state or death in the nonresponders.
Abstract: The purpose of this study was to examine the changes in cerebral hemodynamics of head-injured patients undergoing barbiturate treatment of refractory intracranial hypertension. Cerebral blood flow (CBF) and metabolism variables were measured in 67 severely head-injured patients at the following times: before the loading dose of pentobarbital; after the loading dose of pentobarbital (average pentobarbital level 28.1+/-8.3 microg/mL); and 3 days later, when the peak pentobarbital level averaged 42.5+/-17.2 microg/mL. Intracranial pressure (ICP) and mean arterial blood pressure (MAP) were decreased by the loading dose of pentobarbital by an average of 12 and 9 mm Hg, respectively. Cerebral perfusion pressure (CPP) was unchanged when the entire group was analyzed together. CBF, cerebral oxygen consumption (CMR(O)2), and arteriovenous oxygen difference (AVD(O)2) were significantly decreased after the loading dose of pentobarbital, by 20%, 31%, and 11%, respectively. The average cerebrovascular resistance (CVR) was increased by 20%. The change in CMR(O)2 with the loading dose of pentobarbital was closely related to the pretreatment value (n = 67, r2 = 0.65, p < .001). Thirty (45%) of the patients had a "good ICP response," with a reduction in ICP from 34+/-9 to 15+/-5 mm Hg after the initial loading dose of pentobarbital. Twenty-seven (40%) of the patients had a "partial ICP response," with ICP decreasing but still remaining above 20 mm Hg after the loading dose of pentobarbital. In the remaining 10 patients, ICP did not change or even increased after pentobarbital. In the 30 patients with a good ICP response, pretreatment CMR(O)2 and AVD(O)2 were greater before administration of pentobarbital, and CMR(O)2 and AVD(O)2 decreased more with the loading dose of pentobarbital, than in the patients with partial or no ICP response. The outcome was significantly better in the patients with a good or partial ICP response to pentobarbital, with 21% of these patients having a good recovery or moderate disability at 3 months after injury, compared with 100% persistent vegetative state or death in the nonresponders. In summary, barbiturate coma can be a useful treatment modality for acutely reducing ICP in selected patients. Patients with overwhelmingly severe injuries are not likely to benefit, partly because their CMR(O)2 is already markedly reduced by the injury and partly because their outcome is already predetermined by the injury. Patients with systemic hypotension are not likely to have a good response because hypotension limits the amount of barbiturates that can be given.
TL;DR: The findings document that high-concentration albumin therapy instituted 15 min after trauma significantly improves the neurological score and reduces histological damage and believe that this pharmacological agent may have promising potential for the clinical treatment of brain injury.
Abstract: We have recently shown that high-dose human serum albumin (HSA) therapy confers marked histological protection in experimental middle cerebral artery occlusion. Thus, the purpose of this study was to determine whether treatment with high-dose HSA would protect in a rat model of traumatic brain injury (TBI). Twenty-four hours prior to TBI, the fluid percussion interface was positioned parasagittally over the right cerebral cortex. On the following day, fasted rats were anesthetized with 3% halothane, 70% nitrous oxide, and 30% oxygen and received right parieto-occipital parasagittal fluid-percussion injury (1.5-2.0 atm). Cranial and rectal temperatures were monitored throughout the experiment and held at normothermic levels (36.5-37.5 degrees C) by a warming lamp above the animal's head. The agent (25% human serum albumin, HSA) or vehicle (sodium chloride 0.9%) was administered i.v. (1% of body weight) 15 min after trauma. Behavioral function was evaluated in all rats before and after TBI (at 2 h, 24 h, 48 h, 72 h, and 7 days). Neurological function was graded on a scale of 0-12 (normal score = 0; maximal score = 12). Seven days after TBI, brains were perfusion-fixed, coronal sections at various levels were digitized, and contusion areas in the superficial, middle and deep layers of cortex and in the underlying fimbria were measured. HSA significantly improved the neurological score compared to saline at 24 h, 72 h, and 7 days after TBI (6.0 +/- 0.6 [albumin] versus 8.4 +/- 0.5 [saline]; 3.6 +/- 0.7 versus 6.8 +/- 1.0; and 2.6 +/- 0.6 versus 5.7 +/- 0.8, respectively; p < 0.05). HSA therapy also significantly reduced total contusion area (0.89 +/- 0.2 versus 1.82 +/- 0.3 mm2; p = 0.02). Our findings document that high-concentration albumin therapy instituted 15 min after trauma significantly improves the neurological score and reduces histological damage. We believe that this pharmacological agent may have promising potential for the clinical treatment of brain injury.
TL;DR: It is hypothesized that mutant mice deficient in ICAM-1 (-/-) would have decreased neutrophil accumulation, diminished histologic injury, and improved functional neurologic outcome versus ICAM -/- wild type control mice after TBI.
Abstract: Intercellular adhesion molecule–1 (ICAM-1) is an adhesion molecule of the immunoglobulin family expressed on endothelial cells that is upregulated in brain as part of the acute inflammatory response to traumatic brain injury (TBI). ICAM-1 mediates neurologic injury in experimental meningitis and stroke; however, its role in the pathogenesis of TBI is unknown. We hypothesized that mutant mice deficient in ICAM-1 (−/−) would have decreased neutrophil accumulation, diminished histologic injury, and improved functional neurologic outcome versus ICAM-1 +/+ wild type control mice after TBI. Anesthetized ICAM-1 −/− mice and wild-type controls were subjected to controlled cortical impact (CCI, 6 m/sec, 1.2 mm depth). Neutrophils in brain parenchyma and ICAM-1 on vascular endothelium were assessed by immunohistochemistry in cryostat brain sections from the center of the contusion 24 h after TBI (n = 4/group). Separate groups of wild-type and ICAM-1–deficient mice (n = 9–10/group) underwent motor (wire gri...