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M S Beattie

Publications and source records attributed to M S Beattie.

At least 19 recordsLinked to original sources
PubMed1995

Distribution of NADPH-diaphorase reactivity in the spinal cord of metamorphosing and adult Xenopus laevis.

The histochemical NADPH-diaphorase reaction has identified distinct neuronal populations in the nervous system of several species. Considerable evidence suggests that NADPH-d is a neuronal nitric oxide synthase (NOS). We examined spinal cords of adult and metamorphosing Xenopus laevis (XL) for developmental differences in NADPH-d reactivity. In adult XL, labeling was found in all dorsal root ganglia (DRGs) and in their termination sites within the dorsal horn (cutaneous afferent field) and intermediate gray (muscle afferent field). Cell bodies in the intermediate gray regions containing the autonomic preganglionic neurons were labeled in thoracic and sacral sections. Neurons located in the medial (MMC) and lateral motor columns (LMC) of the ventral horn were also stained. In metamorphosing XL, reactivity was detected in neurons in the intermediate gray, in the MMC and in the LMC as in the adult. Additionally, primary motoneurons including those innervating tail musculature were labeled. Neurons in the DRGs were stained at all stages; in the dorsal horn, the density of staining reflected the development of the sensory afferent fields. The conservation of NADPH-d reactivity in adult and metamorphosing XL spinal neurons suggests that NOS may be involved in processes independent of developmental changes occurring in XL spinal cord.

Animals↗
PubMed1995

A sensitive and reliable locomotor rating scale for open field testing in rats.

Behavioral assessment after spinal cord contusion has long focused on open field locomotion using modifications of a rating scale developed by Tarlov and Klinger (1954). However, on-going modifications by several groups have made interlaboratory comparison of locomotor outcome measures difficult. The purpose of the present study was to develop an efficient, expanded, and unambiguous locomotor rating scale to standardize locomotor outcome measures across laboratories. Adult rats (n = 85) were contused at T7-9 cord level with an electromagnetic or weight drop device. Locomotor behavior was evaluated before injury, on the first or second postoperative day, and then for up to 10 weeks. Scoring categories and attributes were identified, operationally defined, and ranked based on the observed sequence of locomotor recovery patterns. These categories formed the Basso, Beattie, Bresnahan (BBB) Locomotor Rating Scale. The data indicate that the BBB scale is a valid and predictive measure of locomotor recovery able to distinguish behavioral outcomes due to different injuries and to predict anatomical alterations at the lesion center. Interrater reliability tests indicate that examiners with widely varying behavioral testing experience can apply the scale consistently and obtain similar scores. The BBB Locomotor Rating Scale offers investigators a more discriminating measure of behavioral outcome to evaluate treatments after spinal cord injury.

Animals↗
PubMed1994

Distribution and morphology of sacral spinal cord neurons innervating pelvic structures in Xenopus laevis.

Relatively little is known about the organization of neural input to pelvic viscera in amphibia. In this study, sacral spinal efferent neurons were labeled in Xenopus laevis frogs by application of horseradish peroxidase (HRP) to the tenth spinal nerve, to pelvic musculature, or to the pelvic nerve. DiI was applied to the pelvic nerve with similar results. Labeled spinal neurons were located in the intermediate gray or in the ventral horn. Neurons in the tenth dorsal root ganglion, but not in the spinal cord, were labeled after application of HRP or DiI to the pudendal nerve. The labeled neurons in the spinal cord intermediate gray were in a position comparable to that of the mammalian sacral parasympathetic nucleus (SPN). Two apparent subdivisions included 1) a medial cluster of cells with mediolaterally oriented dendrites and 2) a lateral group with dorsoventrally oriented dendrites. An intermediate group, not clearly classed with the other two, was also identifiable. In some cases, labeled tenth nerve primary afferents were seen in contact with efferent neurons of the intermediate gray. Labeled neurons in the ventral horn medial to the lateral motor column were small, with dendrites oriented mediolaterally, in a position comparable to that of the mammalian Onuf's nucleus. The peripheral targets of DiI-labeled pelvic nerve axons were the compressor cloaca muscle, cloaca, and bladder. DiI-labeled pudendal nerve axons distributed peripherally to cloacal lip and medial thigh integument. These data suggest that the pudendal nerve in amphibians is purely sensory and that both somatic and autonomic motor axons traverse the pelvic nerve.

Animals↗
PubMed1992

Spinal cord injury produced by consistent mechanical displacement of the cord in rats: behavioral and histologic analysis.

We examined the ability of an electromechanical device to produce consistent and incomplete thoracic (T9) spinal cord injuries in rats by brief displacement (Dspl) of the exposed dural surface. Open field walking, inclined plane, grid walking, and footprint analysis, and a determination of the percentage of tissue spared at the lesion center were used to assess chronic outcome (6 weeks postinjury). Laminectomy control animals showed no evidence of a functional deficit or histologic lesion. Complete spinal cord transections in normal rats and in a group of animals previously injured (1.1 mm Dspl) and allowed to recover resulted in complete loss of hindlimb function, demonstrating an important functional role for the remaining spared fibers at the lesion site. Consistent spinal cord displacements (0.80 mm, 0.95 mm, and 1.10 mm) resulted in behavioral groups with low outcome variability over a narrow range of incomplete recovery of neurologic function. Significant behavioral (open field walking, inclined plane, and grid walking) and histologic differences were found between the control and Dspl groups and between the 0.80 mm and 1.10 mm Dspl groups. Significant correlations were observed among the injury parameters, behavioral, and histologic scores. Open field walking and inclined plane performance were sensitive indicators of both the early and late phases of neurologic recovery. Grid walking was most useful in animals with small chronic residual deficits. The footprint analysis resulted in less significant correlations and differences between the behavioral groups than the other outcome measures. This may result from a relatively narrow range of sensitivity (open field walking scores between 3.3 and 4.0) and increased variability within the groups.

Animals↗
PubMed1991

Three-dimensional computer-assisted analysis of graded contusion lesions in the spinal cord of the rat.

Histological analysis of spinal cord injury in experimental animals has focused primarily on the microanatomy of damaged tissue. The current study presents an analysis of the three-dimensional structure of lesion sites in the spinal cord of rats contused with an injury device which produces consistent lesions. Three levels of injury were produced by systematically varying the cord displacement and the duration of the displacement during impact. The resulting groups of subjects exhibited mild, moderate, and severe neurological deficits. Comparisons of equivalent mild impacts made at thoracic versus lumbar spinal cord levels were also made. The results indicate that the overall shape of the lesions is generally biconical, with extensions in the base of the dorsal funiculus, irrespective of the degree of damage or the spinal level of the injury. Lower displacement injuries yielded shorter lesions rostrocaudally with less spread into the white matter. Similar impacts in the lumbar versus thoracic spinal cord produced shorter, more truncated lesion sites at lumbar levels with less involvement of the white matter than in the thoracic lesions. Three-dimensional analyses can can provide additional information about the lesion beyond that available from conventional histopathological measures. Such information could be useful in assessing the results of posttraumatic manipulations which are directed at reducing tissue damage or tissue replacement via transplantation.

Animals↗
PubMed1990

Motoneurons innervating the external anal and urethral sphincters of the female cat have different patterns of dendritic arborization.

The locations and dendritic arbors of sacral motoneurons (MNs) innervating the striated external anal and urethral sphincters (EAS and EUS, respectively) of the cat were investigated using muscle injections of cholera toxin-conjugated HRP (CT-HRP). Serial reconstructions showed that all cells labelled after EAS injections were located in the dorsomedial (DM) subdivision of Onuf's nucleus, whereas all cells labelled from the EUS were located in the ventrolateral (VL) subdivision. The dendritic arbors of EAS and EUS MNs were very different, suggesting differences in afferent control. In addition, prominent bundles of dendrites extended preferentially into the regions occupied by functionally appropriate preganglionic neurons (PGNs) in the sacral parasympathetic nucleus (SPN) which innervate the colon and bladder.

Anal Canal↗
PubMed1990

Metamorphosis alters the response to spinal cord transection in Xenopus laevis frogs.

A series of studies has examined the response of the spinal cord to lesions made at various stages prior to and after metamorphic climax in the clawed frog Xenopus laevis. Complete transections made between Nieuwkoop and Faber (1956) stages 50 and 62 were followed by gradual recovery of righting and coordinated swimming as animals metamorphosed into juveniles (stage 66). Examination of descending axonal projections using horseradish peroxidase (HRP) showed fibers crossing the lesion site and distributing to the caudal lumbar spinal cord. These fibers could be traced from more rostral spinal segments as well as from brainstem injections of HRP. No evidence for rostrally projecting fibers crossing the lesion was obtained. Juvenile frogs of varying ages failed to demonstrate recovery of coordinated swimming or reconstitution of spinal descending pathways. In an additional series of animals, spinal transections were made within 1 or 2 days of tail resorption to assess whether regenerative capacities extended at all into post-metamorphic stages. No evidence for regeneration was found. Studies of metamorphosing frogs after spinal transections showed that fibers crossed the lesion within 5-12 days of transection, well prior to the end of metamorphic climax; however, in some cases in which metamorphosis seemed arrested, little regeneration was observed. Immunocytochemical studies showed that fibers containing serotonin (5-HT) were included in the population of axons that rapidly crossed the lesion after transection at metamorphic stages. These results are compared to those for lesions of the dorsal columns and other systems in developing and juvenile Xenopus. It is suggested that both metamorphosis-related hormonal changes, and axon substrate pathways, may affect the regenerative response in the Xenopus central nervous system (CNS).

Animals↗
PubMed1989

Lymphocyte entry into inflammatory tissues in vivo. Qualitative differences of high endothelial venule-like vessels in sponge matrix allografts vs isografts.

Sponge matrix allografts and isografts become extensively encapsulated and neovascularized after s.c. implantation. Sponge allografts acquire alloantigen-reactive T lymphocytes, whereas sponge isografts fail to do so, even though these T cells are continuously circulating in the peripheral blood. We have investigated the possibility that the vascular endothelia regulates lymphocytic accumulation in sponge matrix implants. In normal lymph nodes, specialized high endothelial venules (HEV) regulate lymphocyte extravasation from the blood. We have now identified HEV-like vessels in sponge matrix allografts. These vessels are operationally defined as "HEV-like" in that they react with mAb MECA 325 which identifies murine HEV, and bind lymphocytes in ex vivo adhesion assays. In contrast, sponge isografts contain MECA 325 reactive vessels that are significantly smaller than those found in allografts. Further, vessels of sponge isografts do not readily bind lymphocytes in ex vivo adhesion assays. Immunohistologic analysis also revealed that the small MECA 325+ vessels present in sponge isografts are consistently found in close proximity to nerve bundles. Although this MECA 325 reactive vessel-nerve bundle association is also observed in sponge allografts, large MECA 325 reactive vessels are widely distributed in allografts. Our data suggest that small, poorly adhesive MECA 325 reactive vessels develop in sponge isografts and allografts, possibly under the influence of local nerve tissue. These vessels respond to regional alloimmune responses by developing into the larger HEV-like vessels capable of binding lymphocytes in sponge allografts. The value of this experimental system as an in vivo model to evaluate mechanisms involved in neovascularization and endothelial differentiation is discussed.

Animals↗
PubMed1988

Differences in synaptic inputs to preganglionic neurons in the dorsal and lateral band subdivisions of the cat sacral parasympathetic nucleus.

In the cat, preganglionic neurons (PGNs) found in the dorsal portion of the sacral parasympathetic nucleus (dorsal band or DB cells) participate in bowel control, while those found along the lateral edge (lateral band or LB cells) influence bladder function. In order to determine whether differences in the synaptic inputs exist between these two populations, HRP was applied to the sacral ventral rootlets of cats, and the S2 cord segment was prepared for sequential light and electron microscopy. When measured with light microscope, the LB somata had greater cross-sectional areas than did the DB cells. Ultrastructurally, the LB cells had a significantly greater percentage of their membrane apposed by synaptic active sites than did the DB cells. Also, the proximal dendrities of the labelled neurons received greater synaptic input than did the somata. No difference was found in the proportion of terminals containing dense cored vesicles (DCVs) when comparing LB and DB somata; however, the LB proximal dendrites had a higher proportion of their surface contacted by DCV-containing terminals than did the DB dendrites. These ultrastructural results offer evidence that these two populations of preganglionic neurons differ with respect to their synaptic input as well as their peripheral targets.

Animals↗
PubMed1987

Testosterone-induced plasticity of synaptic inputs to adult mammalian motoneurons.

The effects of testosterone administration on penile reflexes, and on the motoneurons of the spinal nucleus of the bulbocavernosus which innervate perineal muscles involved in these reflexes, were investigated in castrated male rats. Penile reflexes were restored following 48 h of testosterone administration initiated 6 weeks after castration. The amount of synaptic input to the identified motoneurons was increased following short term testosterone treatment, compared to that seen in animals receiving no testosterone, albeit to a lesser extent than that seen in animals receiving long term testosterone treatment. This increase in synaptic inputs in the short term testosterone group occurred despite the lack of an increase in somatic area. Thus, plasticity of the synaptic input to these neurons, as well as recovery of penile reflexes, occurred as a result of alterations in the hormonal state of the animal, and such changes occurred relatively rapidly.

Afferent Pathways↗
PubMed1987

Distribution and ultrastructure of ventral root afferents to lamina I of the cat sacral spinal cord.

Following ventral root injury-filling with horseradish peroxidase at sacral spinal levels S1, S2, and S3, small fascicles of axons can be observed to enter the ventral portion of lamina I and arborize primarily in the dorsolateral region just medial to the tract of Lissauer (TL). Some axons enter the TL and turn in a rostrocaudal direction. Labeled axons studied by electron microscopy are both myelinated and unmyelinated, and terminals in lamina I contain round clear, and dense cored vesicles and contact smaller diameter dendrites and vesicle-containing elements. The concentration of these putative ventral root afferents appears to be largest in the S2 segment, with smaller numbers found within S1 and S3.

Animals↗
PubMed1987

Circumferential cells of the developing Rana catesbeiana lumbar spinal cord.

Neural elements in the lumbar enlargement of the developing Rana catesbeiana spinal cord were labelled by placing chips of dessicated horseradish peroxidase (HRP) into various lesions of the spinal cord. Of the elements labelled in the lumbar enlargement, a population of cells circumjacent to the gray matter was seen to be distinct from all others on the basis of their morphology, position and their putative embryonic origin. One cell type not previously described was a large circumferential cell (LCC) with primary processes completely circumscribing the gray matter. The ventral process crosses the midline and ascends or descends in the ventral funiculus. The dorsal primary process was observed to extend to the midline and turn ipsilaterally in a rostro-caudal direction in the dorsal funiculus. LCC's were present at early stages of larval development (stage III, Taylor and Kollros 1946) but could not be labelled in juvenile frogs. LCC's were only observed in the lumbar enlargement and could only be labelled through HRP applications at that level. They receive abundant synaptic input from the ipsilateral lateral funiculus. Possible roles for the LCC in the early function and development of the ranid lumbar spinal cord are discussed.

Aging↗
PubMed1987

A behavioral and anatomical analysis of spinal cord injury produced by a feedback-controlled impaction device.

In order to provide a reproducible experimental spinal cord injury with immediate feedback on the mechanical properties of the impact, we have developed an electro-mechanically driven, feedback-controlled impaction device. The device is sensitive to the characteristics of the injured tissue and allows continuous manipulation of impact force or tissue displacement. The current study describes the anatomical and behavioral outcomes of a range of impacts and examines the ability of the device to produce a consistent traumatic injury. Rats were subjected to spinal cord trauma at the midthoracic level. Group II received a wide range of impacts that were preset at a desired force level and group III received impacts preset for a constant displacement of the spinal cord surface. Group I served as laminectomy controls. Behavioral testing included assessments of general and fine locomotor skills (open field and grid walking) and postural adjustment to displacement (inclined plane). Lesion volumes and percentage area of the cord occupied by the lesion were assessed postmortem. For group II, significant correlations between the physical descriptors of the impact and the behavioral measures were observed early during the postoperative period for open field and inclined plane performance and later in the recovery period for grid walking. Lesion measures correlated significantly with impact descriptors and with behavioral measures as well. Group III showed consistent behavioral deficits which partially recovered in the postoperative interval. The behavioral results correlated well with the lesion measures for this group also. The results indicate that it is possible to produce an intermediate lesion in the rat which results in consistent recovery with a residual deficit 3 weeks postoperatively, using a device that allows for immediate assessment of the physical descriptors of impact trauma.

Animals↗
PubMed1986

A light and electron microscopic analysis of the sacral parasympathetic nucleus after labelling primary afferent and efferent elements with HRP.

Primary afferent input to the cat sacral parasympathetic nucleus (SPN) has been examined by injury filling sacral dorsal roots, ventral roots, or both with horseradish peroxidase (HRP). Appropriate spinal segments were processed for the demonstration of HRP with diaminobenzidine and prepared for sequential light (LM) and electron (EM) microscopy. At the LM level, a large fascicle of primary afferent fibers was observed passing ventrally along the lateral edge of the dorsal horn into the region of the SPN. Varicosities were seen throughout the course of the axons but were particularly abundant within the SPN. Injury filling of the ventral roots with HRP resulted in a Golgi-like labelling of preganglionic neurons and their dendritic arbors, as well as ventral root afferent fibers. Swellings on both dorsal and ventral root afferent axons were observed in close apposition to labelled preganglionic neurons and their dendrites. At the ultrastructural level, afferent terminals were found to contain clear spherical vesicles; 66% of these terminals also contained at least one dense-cored vesicle. Of particular interest was the presence of labelled dorsal and ventral root afferent terminals synapsing on labelled preganglionic neurons. Preganglionic neurons were also postsynaptic to unlabelled terminals containing clear spherical (79.7%) or pleomorphic vesicles (20.3%). These data indicate that preganglionic neurons receive direct input from several sources, and provide the first demonstration of direct input to these cells from sensory fibers in the dorsal and ventral roots. The connections described in the present study provide interesting and, as yet, unexplored possibilities for sensory and autonomic reflex integration.

Animals↗
PubMed1985

The development of the relationship between dorsal root afferents and motoneurons in the larval bullfrog spinal cord.

The relationship of dorsal root afferents to motoneuron somata and dendrites was studied by labelling dorsal and ventral roots of the tadpole lumbar enlargement with HRP at different stages of hindlimb development. Procedures were used which allowed for sequential light and electron microscopic analysis to determine whether close appositions between labelled elements represented synaptic contacts. Lateral motor column (LMC) motoneuron dendrites grow first into the lateral funiculus, and later begin arborizing within the spinal gray, concurrent with the arrival of developing dorsal root afferent fibers. Mature-appearing synaptic contacts between dorsal root afferents and motoneuron dendrites are established first on distal dendrites, and are observed on progressively more proximal dendrites as hindlimb development proceeds. Migrating motoneurons were also labelled in some animals. Distinct dorsal and ventral migratory pathways were noted; cells migrating dorsally were contacted by developing dorsal root afferents. Migrating motoneurons were associated with radially oriented processes, and were often closely apposed to other cells. The coincident development of dorsal root projections and the motoneuron dendrites which these fibers innervate in the adult, as well as the interaction between these two systems during cell migration, suggest that these two systems may be interdependent in establishing their normal relationship during development.

Animals↗