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J R Wrathall

Publications and source records attributed to J R Wrathall.

At least 55 records · Page 3Linked to original sources
PubMed1989

Correlative analyses of lesion development and functional status after graded spinal cord contusive injuries in the rat.

The development of both histopathological changes and functional deficits was quantitatively assessed after mild, moderate, and severe spinal cord contusive injuries. The cross-sectional area of the spinal cord at the epicenter (region of maximal damage) and the areas of hemorrhage, lesion, and remaining gray and white matter were determined from 15 min to 8 weeks after injury. From 24 h to 8 weeks after injury, functional deficits were quantified using a combined behavioral score (CBS) based on the results from a number of behavioral tests of function. Regression analysis was used to examine the correlations between the amount of residual white matter and both the severity of contusive impact and the functional deficit over time after injury. The area of hemorrhage at 15 min and 24 h was greater in the mild and moderate injury groups than after the severe contusive injury. Significant loss of gray and white matter occurred primarily between 24 h and 1 week after injury along with concomitant increases in the area of lesion. In the mild injury group the rate of lesion development appeared slower than that in the moderate and severe injury groups and significant white matter loss continued to occur between 1 and 4 weeks after injury. Behavioral tests of functional deficit were performed at 24 h and weekly thereafter. The development of stable functional deficits was observed beginning at 3 weeks after injury. There was a significant correlation between residual white matter and the degree of initial injury at 24 h after injury and all subsequent time points. However, a significant correlation between residual white matter and functional deficit, as measured by the CBS, was not observed at 24 h or 1 week but did develop by 4 weeks after injury.

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PubMed1988

Blood-spinal cord barrier disruption proximal to a spinal cord transection in the rat: time course and pathways associated with protein leakage.

The effects of spinal cord transection on the blood-spinal cord barrier of the rat were examined at the ultrastructural level at sites 0.5 and 1.0 cm proximal to the injury. Using the vascular tracer horseradish peroxidase (HRP), the time course and pathways of barrier disruption were evaluated. At 0.5 cm, barrier disruption was noted from as early as 15 min and continued to 12 h after injury, whereas at 1.0 cm, evidence for vascular permeability was confined to between 15 min and 3 h. The presence of barrier breakdown to exogenous protein at a distance from the transection emphasizes that injury promotes a more generalized vascular response which likely contributes to subsequent edematous changes. The mechanism(s) involved in increased permeability appears to be primarily related to transendothelial vesicular transport of the tracer. There was no evidence for interendothelial leakage of the tracer across compromised tight junctions. In comparing these findings with those reported on sites distal to a transection, it is clear that there is an asymmetry in the vascular response to HRP. The pinocytotic index, an indicator of endothelial uptake of HRP, was significantly elevated (compared with control) distal to a transection from 3 h through 3 days after injury, attaining a maximum at 12 h. In contrast, the pinocytotic index proximal to a transection was significantly elevated compared to control values at only 1 h after injury. Furthermore, at 3 h after injury, when barrier disruption was most prominent, there was a smaller percentage of vessels exhibiting leakage to HRP proximal as opposed to distal to a transection.

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PubMed1988

Spinal cord contusion in the rat: somatosensory evoked potentials as a function of graded injury.

A weight-drop technique was used to produce mild, moderate, or severe spinal cord contusive injury in rats. At 4 weeks after injury, somatosensory evoked potentials (SEPs) were recorded with silver ball electrodes placed over the somatosensory cortex of anesthetized rats to measure the response to sciatic nerve stimulation. Both SEP area and amplitude were measured and were highly correlated with each other. Both indices of the SEP correlated inversely with the height of the weight drop and directly with the degree of residual function assessed at 4 weeks after injury. Measures of residual function consisted of a motor score, inclined plane test, and a combined behavioral score based on several neurologic functions. No correlation between latency of the SEP with degrees of contusive injury was observed. The data indicate that the SEP can be used as one criterion in the assessment of the severity of a lesion in a rat model of a graded spinal cord injury.

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PubMed1988

Biomechanical analysis of experimental spinal cord injury and functional loss.

Spinal cord injury was studied using a drop-weight technique in a rat model. A constant weight of 10 g was dropped from 2.5, 5.0 and 17.5 cm heights. The trauma delivered was quantified by biomechanical parameters of weight drop height, maximum force, and impulse, while the functional deficit produced by injury was quantified in terms of the maximum inclined plane score, hindlimb motor score, and combined behavioral score. Highly significant (P = 0.0001) relationships were found within the biomechanical parameters of trauma as well as between the trauma and the functional parameters at 4 weeks after injury. The impulse was found to be the best predictor of the functional loss (r = 0.79, P = 0.0001).

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PubMed1987

The blood-spinal cord barrier after injury: pattern of vascular events proximal and distal to a transection in the rat.

The effect of spinal cord transection on the blood-spinal cord barrier was examined at both the light and electron microscopic levels using the vascular tracer, horseradish peroxidase (HRP). At the light microscopic level, the pattern of hemorrhage and distribution of reaction product were examined and quantified at 0.5, 1.0, and 2.0 cm proximal and distal to the transection. The morphometric data supports the hypothesis that regions of the cord that are distal to a transection, exhibit a more pronounced vascular disruption than at comparable sites proximal to the injury. This asymmetry is not apparent until 1 day after injury and is characterized by an increase in the areas of hemorrhage and reaction product at 1.0 and 2.0 cm distal to the transection as compared to similar sites proximal. In previous ultrastructural studies we demonstrated that the primary mechanism for barrier breakdown distal to a transection appeared to be transendothelial vascular transport of the tracer. In the present study, we extended these observations to sites proximal to a transection and confirmed that a similar mechanism of barrier breakdown occurs. There was no evidence for interendothelial passage of tracer across compromised tight junctions. Further studies are under way to quantify the vesicular transport in order to determine if differences in the intensity of this response contribute to the asymmetry in barrier permeability demonstrated by light microscopy.

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PubMed1987

An inexpensive apparatus for producing graded spinal cord contusive injury in the rat.

We recently described an experimental model of spinal cord contusive injury in the rat in which a modified weight-drop apparatus is used to generate reproducible mild, moderate, or severe final functional deficit. We now report several inexpensive alternatives for portions of the original apparatus which allow the production of contusive injuries without the necessity of an expensive commercial stereotaxic frame or custom-machined clamp holders.

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PubMed1987

Behavioral assessment of functional deficit in rats with contusive spinal cord injury.

We have previously reported a method for assessing functional deficits in rats after contusive spinal cord injury in which a Combined Behavioral Score (CBS) is calculated that is indicative of the overall percent deficit (Exp. Neurol., 88: 123-134, 1985). The test battery used includes several neurologic tests as well as the Motor Score in which use of the hindlimbs in locomotion is graded. In this report we present correction criteria in order to reduce potential interlaboratory variability in assessing functional deficit by the CBS. Groups of rats were subjected to contusive injury using a weight drop technique. The calculated CBS at 4 weeks was compared to that obtained if the Motor Score was over- or underestimated by 1 grade. The results indicated a considerable effect on the calculated CBS, especially when the Motor Score was underestimated in mildly injured animals. Behavioral test data were examined in terms of the distribution of the responses to the various other behavioral tests in relation to the Motor Score. The results were used to develop a set of correction criteria that minimized the effects on the CBS of subjective errors in the Motor Score.

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PubMed1986

Reduced neuronotrophic activity of fibroblasts from individuals with dysautonomia in cultures of newborn mouse sensory ganglion cells.

The neuronotrophic activity of human skin fibroblast cell lines from two normal individuals and 3 individuals with Familial Dysautonomia (FD) was compared in terms of their ability to support neuron survival and neurite regeneration in cultures of newborn mouse sensory neurons. Neuronotrophic activity was assayed by culturing dissociated sensory neurons from newborn mice: (1) on fibroblast 'cell beds' consisting of monolayer cultures of living fibroblasts, (2) with medium that had been conditioned by monolayer fibroblast cultures and (3) with extracts of the cultured fibroblasts. Neurite regeneration was compared by determining the percentage of neurons that had regenerated neurites after 24 or 48 h in culture. Neuron survival was determined by counts at 48 h, 7 days and 14 days after culture initiation. Neurite regeneration and neuron survival was found to be significantly less on FD cell beds or with FD-conditioned medium than in replicate cultures with normal fibroblasts or their conditioned medium. The reduced neuronotrophic activity of FD fibroblasts or conditioned medium was still observed in the presence of antibody sufficient to block the neuronotrophic effects of purified nerve growth factor (NGF). Thus, fibroblasts from individuals with FD exhibit reduced neuronotrophic activity for newborn mouse sensory neurons that appears to be due to factor(s) other than NGF.

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PubMed1986

Localization of dynorphin gene product-immunoreactivity in neurons from spinal cord and dorsal root ganglia.

Using spinal cord and dorsal root ganglion cell cultures, we have studied the immuno-histochemical distribution of several peptide products of the dynorphin gene. With antibody directed toward the midregion of dynorphin A, peptide-immunoreactivity was found exclusively in the cell bodies of spinal cord neurons. Antibody directed toward the amino- or carboxy-terminus of dynorphin A revealed peptide-immunoreactivity in the neurites, as well as perikarya. Spinal cord neurons also expressed dynorphin B- and alpha-neo-endorphin-immunoreactivities in both cell bodies and neurites. Dorsal root ganglion neurons cultured from embryonic tissue expressed dynorphin A-(1-13)-, dynorphin A-(9-17)- and dynorphin B-immunoreactivities in their perikarya. Sensory neurons obtained from dissociated adult ganglia similarly expressed dynorphin-immunoreactivity immediately upon inoculation into culture. Embryonic and adult murine sensory ganglia from the sacral region more frequently expressed dynorphin than did cells obtained from other spinal levels. Expression of dynorphin-immunoreactivity by sensory neurons was not influenced by elevated levels of Nerve Growth Factor or spinal cord conditioned medium. These data indicate that intrinsic spinal cord neurons may modulate sensory and spinal function in rather subtle ways via the expression of several different opioid peptide products of the dynorphin gene, in addition to the opioid peptides produced by the proenkephalin A gene. Beyond this, the observation of dynorphin-related peptides in dorsal root ganglion neurons suggests that these opioid peptides may have a specialized role in primary afferent neurotransmission.

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PubMed1985

Localization of elevated glutaminase immunoreactivity in small DRG neurons.

Glutamate has long been considered to be a neurotransmitter candidate in vertebrate spinal sensory nerve cells. We report here the first immunohistochemical evidence in support of this hypothesis. We find that up to 30% of the moderately small dorsal root ganglion neurons in the rat contain elevated levels of glutaminase immunoreactivity. This enzyme, which mediates the synthesis of glutamate from glutamine, is not found at these high levels in large diameter neurons of the same ganglia. In contrast, another enzyme associated with glutamate metabolism, aspartate aminotransferase, is rather uniformly distributed within neurons of the sensory ganglia. These data define a subpopulation of sensory neurons which appear to contain an elevated capacity to synthesize glutamate through the glutamine cycle and suggest that glutaminase immunoreactivity may be an indicator of glutamatergic function in some nerve cells.

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PubMed1985

Spinal cord contusion in the rat: production of graded, reproducible, injury groups.

A weight drop technique was used to produce a contusive injury of the spinal cord in the rat. A restricted laminectomy was carried out at T8 and the spinal column stabilized by clamps attached to the spinous processes of adjacent vertebrae. A 2.4-mm-diameter impounder was lowered onto the dura and a 10-g weight dropped 0.0, 2.5, 5.0, 7.5, 10.0, or 17.5 cm onto the impounder. The functional deficit was assessed for 4 weeks after injury and the spinal cord tissue processed for histopathologic analysis. The results indicated that groups of rats (N = 10) subjected to the weight dropped from increasing heights exhibited a graded final functional deficit as measured by scores on a modified Tarlov scale or the mean angle attained in the inclined plane test of Rivlin and Tator. Histopathologic results also indicated the production of graded lesions. Three groups of experimental animals were statistically distinguished corresponding to those with mild, moderate, or severe final functional deficit. The average functional deficit in these injury groups, produced by dropping the weight 2.5, 5.0, or 17.5 cm, respectively, was reproducible in replicate experiments. This model of spinal cord contusion in the rat may be useful in screening putative therapeutic drug regimens for subsequent clinical trials on different groups of patients with spinal cord injury.

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PubMed1985

Spinal cord contusion in the rat: behavioral analysis of functional neurologic impairment.

A graded spinal cord injury in rats was produced by dropping a 10-g weight from 2.5, 5.0, 10,0, or 17.5 cm onto the exposed dura at the T8 vertebral level. Groups of rats (N = 10) for each of these weight drop (WD) levels as well as unoperated and WD controls (0 cm) were subjected to behavioral analysis that included evaluation of simple and complex reflexes as well as spontaneous and evoked motor patterns. On the basis of this analysis, we developed a protocol for evaluating functional deficits that follow spinal cord injury in the rat. The resulting combined behavioral score, a measure of functional deficit, closely correlated with the magnitude of the mechanical injury. The protocol used for neurologic assessment was administered routinely by personnel who were easily and rapidly trained. It should therefore prove useful in detecting the effects of treatment on recovery of function in a rat model of spinal cord injury.

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PubMed1985

Spinal cord contusion in the rat: morphometric analyses of alterations in the spinal cord.

Morphometric analyses were carried out on rat spinal cords which were injured by a weight drop technique. A 10-g weight was dropped 0.0, 2.5, 5.0, 7.5, 10.0, or 17.5 cm onto the dura which was exposed at the T8 vertebral level. Four weeks after injury, lesion volume, lesion length, and the dimensions of the tissue at the epicenter (lesion area, area of gray matter, and area of white matter) were measured and correlated with the height from which the weight was dropped and the results from tests of motor and sensory functional deficit. The results, based on linear regression analyses, indicated significant correlations between certain morphologic parameters (lesion volume, lesion length, and the area of gray and white matter at the epicenter) and both the height from which the weight was dropped and behavioral scores. Because the area of white matter at the epicenter is a very simple measurement which correlates well (r = 0.91) with behavioral outcome, this morphologic feature is a useful quantitative measure of the histopathologic consequences of spinal cord injury.

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PubMed1984

Observation of cultured peripheral non-neuronal cells implanted into the transected spinal cord.

We have previously reported that cultured peripheral non-neuronal cells could be used as an adjunct to spinal cord reconstruction with the delayed nerve graft technique. The cultured cells appeared to enhance axonal regeneration and with their use the time it took for axons from the spinal cord stumps to reach the nerve graft was reduced. To gain insight into the possible mechanisms through which peripheral non-neuronal cells can foster CNS regeneration, we have now investigated the behaviour of the peripheral non-neuronal cells after implantation into the spinal cord. Autologous mixed non-neuronal cell cultures were prepared from cat sciatic nerve biopsies and labeled in culture with tritiated thymidine. The labeled cells were implanted so as to completely fill the gap in the spinal cord produced by a narrow "slit transection". Light-and electron-microscopic autoradiography was used to identify the cells 3 and 7 days after implantation and to determine their proximity to, and possible interaction with, axons in the spinal cord stumps. The implanted peripheral cells were frequently found near spinal cord axons and axon terminals. Some of the labeled cells ensheathed axons in which case they displayed morphological characteristics of Schwann cells. Other labeled cells had characteristics of fibroblasts and were surrounded by an extracellular matrix rich in collagen fibrils. Many of the labeled cells contained phagocytosed myelin debris. These observations are consistent with the implanted cells acting to enhance regeneration in the spinal cord either by direct interaction with axons (ensheathment) or indirectly via the production of soluble neuronotrophic factors or a favorable extracellular matrix. The ability of the implanted cells to rapidly move into the spinal cord stumps and attain positions close to spinal cord axons would be an important factor for any of these mechanisms.

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PubMed1983

Histopathology and host response associated with reduced tumorigenicity of 5-bromodeoxyuridine--treated murine melanoma cells.

Growth of B16 murine melanoma cells (clone B559) with low concentrations of 5-bromodeoxyuridine (BrdUrd) has previously been shown to have little effect upon cell proliferation in culture but to significantly reduce the tumorigenicity of the cells when they are injected into adult syngeneic mice. To determine the fate of BrdUrd-grown cells in vivo, we compared the sites of injection of control, fully tumorigenic B559 cells, and BrdUrd-grown cells (3 micrograms/ml for 3 days, termed 3BRM cells) with greatly reduced tumorigenicity (only 8%). We found no evidence of even a transitory period of progressive growth in vivo of BrdUrd-grown cells. At sites of injection of 3BRM cells, as early as Day 1 after injection, there was a significantly lower proliferation rate of the melanoma cells, significantly greater numbers of infiltrating host mononuclear cells, and a significantly higher ratio of host mononuclear to melanoma cells. There was no evidence of endothelial cell proliferation or neovascularization at the sites of 3BRM cells. When sites of injection at 1 day after injection were examined electron-microscopically, evidence of host melanoma cell interactions was more frequently observed at sites of 3BRM cells. The results suggest that the reduced tumorigenicity of BrdUrd-grown melanoma cells may be due to cytostatic and/or cytotoxic influences generated by an enhanced mononuclear cell response. Because the host response occurs so quickly, the involvement of natural killer cells is postulated.

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PubMed1982

Reconstruction of the contused cat spinal cord by the delayed nerve graft technique and cultured peripheral non-neuronal cells.

Previously, surgical reconstruction of the transected dog spinal cord by the delayed nerve graft technique has been shown to result in reinnervation of the nerve graft by axons. In the present study, we compared the results of surgical reconstruction of the severely contused cat spinal cord by the delayed nerve graft technique alone to those after reconstruction with a similar nerve graft plus cultured peripheral non-neuronal cells implanted between the grafted nerve and the spinal cord stumps. The spinal cord-nerve graft junction was examined by light and electron microscopy. The cultured cells were prelabelled with tritiated thymidine and their location after implantation determined by autoradiography. By 3 days after spinal cord reconstruction, the prelabelled cells were present at the junction and had migrated into the nerve graft and also into the spinal cord stumps where they were observed near axons. By 7 days, physical connections were observed bridging the junction between the spinal cord and nerve graft and axons ensheathed by Schwann cells had already penetrated at least 1 mm into the nerve graft. Wound healing took at least a week longer in animals repaired with a nerve graft alone. At one year or later after reconstructive surgery, in both groups of animals, the grafted nerve was reinnervated with myelinated and unmyelinated axons. Thus, the severely contused cat spinal cord could be reconstructed with the delayed nerve graft technique alone but the use of the cultured cells appeared to enhance wound healing and decrease the time required for axon elongation into the nerve graft.

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PubMed1981

Non-neuronal cell cultures from dorsal root ganglia of the adult cat: production of Schwann-like cell lines.

There are several methods available for the production of Schwann cell cultures from fetal and neonatal peripheral nervous tissue. We have investigated methods for producing Schwann cell-rich cultures from adult tissue. Dorsal root ganglia from normal adult cats were used to initiate explant cultures or subjected to primary dissociation. The resulting cultures were compared in terms of growth, the proportions of fibroblastic and Schwann-like cells in primary cultures and the effects of subculture on the relative frequency of these cell types. We found that excision and transfer of explanted ganglion pieces after 14 days in culture produced a secondary outgrowth rich in small, bipolar, spindle-shaped Schwann-like cells. Subculture of this outgrowth produced secondary cultures of predominantly Schwann-like cells with typical spindle-shaped morphology. The use of antimitotic agents in the media to inhibit fibroblast growth was not observed to be necessary or beneficial with this adult tissue. Primary dissociation of ganglia with enzymes (trypsin or collagenase) and mechanical agitation was even more effective in producing secondary cultures and cell lines that were, by morphological criteria, predominantly or exclusively Schwann-like cells. One of these Schwann-like cell lines, designated GSA, has been carried over 24 subcultures while retaining characteristic Schwann cell morphology. Cells of this line have been examined by scanning and transmission electron microscopy. Karyotype analysis indicates a chromosome complement consistent with the species of origin, a normal cat.

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