Expression of active caspase-3 in mitotic and postmitotic cells of the rat forebrain.

Active caspase-3 immunoreactivity was detected in the rat forebrain proliferative regions at birth and remained high in these areas for about 2 weeks, during which period labeled cells were present centroperipherally across the olfactory bulb. By the end of the third postnatal week, only a small number of immunolabeled cells remained in these forebrain structures. Active caspase-3 immunolabeling was localized mostly to cell nuclei and co-localized partially with TuJ1 and NeuN immunoreactivity, but not with glial fibrially acidic protein, OX-42, gamma-aminobutyric acid, or terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL)-positive labeling. Active caspase-3 and 5-bromo-2'-deoxyuridine (BrdU) double-labeled nuclei were seen in the proliferative regions after 2 hours and in the periglomerular region of the bulb after 7 days following BrdU injections. Examination of the cells with electron microscopy confirmed that the active caspase-3-containing nuclei in the proliferative regions often had infoldings and appeared to be undergoing division. Some of the cells with active caspase-3-labeled nuclei in the bulb had synapses on their somata or dendrites. Labeled dendritic spines and a few axon terminals were also observed in the olfactory bulb. Taken together, it appears that a wave of active caspase-3-positive cells are dividing in the proliferative zones and then migrating to the bulb as they differentiate into neurons. Therefore, active caspase-3 may play a role in cellular processes such as neuronal differentiation, migration, and plasticity, in addition to its role in cell death.

Multidimensional chemotopic responses to n-aliphatic acid odorants in the rat olfactory bulb.

In an effort to understand the means by which similar chemical odorants are encoded in the mammalian brain, we exposed rats to a homologous series of n-aliphatic acids and mapped the response of the entire olfactory bulb glomerular layer by using a high-resolution [14C]-2-deoxyglucose uptake technique. We found that these similar odorants evoked spatially clustered but distinct responses in the bulb that changed systematically with carbon chain length. In addition to these chemotopic responses, different odorants within the series evoked systematic differences along two other dimensions: amount of deoxyglucose uptake and extent of the glomerular layer showing high activity. Increases along these two dimensions also were correlated with increasing carbon number. The focal glomerular responses were mirrored by responses in deeper bulb layers. Decreasing the odorant concentration decreased the deoxyglucose uptake within focal regions. The focal regions of activity occurred in pairs involving both medial and lateral representations in the bulb, perhaps reflecting the paired medial and lateral projections of olfactory sensory neurons expressing specific types of odorant feature receptor proteins. The observed spatial pattern of response also may explain both the failure of some bulb lesions to interfere with behavioral olfactory responses and the success of other lesions in blocking olfactory responses. These data support a model of parallel, distributed processing of odorants along multiple dimensions. They also support the notion that analyses of the spatial relationships among odorant responses in the olfactory bulb can demonstrate aspects of the mechanism for odor chemical coding.

Spatial coding of odorant features in the glomerular layer of the rat olfactory bulb.

In order to determine whether molecular features of odorants are represented spatially in the glomerular layer of the olfactory bulb, we used metabolic mapping of [14C] 2-deoxyglucose uptake in rats exposed to equal vapor concentrations of odorants differing systematically in chemical structure. The odorants were ethyl acetate, ethyl butyrate, isoamyl acetate, and isoamyl butyrate. Statistical analysis of anatomically standardized arrays of uptake revealed that each ester produced a characteristic spatial pattern of activity in the glomerular layer. The patterns were similar in different rats exposed to the same odorant, and their complexity increased with increasing odorant carbon number. This finding suggests that the presence of more potentially recognized molecular features is associated with a greater number of activated receptors. Individual regions of the glomerular layer responded specifically to isoamyl esters, and other regions preferred ethyl esters. Regions of similar specificity occurred in lateral and medial aspects of the bulb, the medial representation being more caudal and ventral than the lateral one. This pattern correlates with projections of olfactory sensory neurons expressing the same putative olfactory receptor gene. The patterns overlapped greatly in the posterolateral and posteromedial glomerular layer, a finding one should predict, given the large overlap in chemical structure across the aliphatic esters. Thus, molecular features appear to be encoded spatially in the glomerular layer, and the identity of the odorant may be determined by a subsequent decoding of the combination of molecular features represented in the glomerular layer.

Granule and mitral cell densities are unchanged following early olfactory preference training.

Early olfactory preference training causes both an increased number of juxtaglomerular cells and an increased number of such cells expressing Fos protein. In contrast, there are fewer cells expressing Fos protein in the granule cell layer after training. Here, we report no change in the number or size of granule and mitral cells as a consequence of these early olfactory experiences.

Early locus coeruleus lesions increase the density of beta-adrenergic receptors in the main olfactory bulb of rats.

Norepinephrine is supplied to both deep and superficial layers of the olfactory bulb through dense projections from the locus coeruleus. Beta-adrenergic receptors are located in nearly all bulb laminae, with high-density foci of beta-1 and beta-2-adrenoceptors present in the glomerular layer. Early olfactory experiences that increase norepinephrine levels in the bulb also decrease the density of beta-1- and beta-2-adrenoceptors, as well as the number of high-density glomerular foci of beta-2-receptors. Changes in bulb norepinephrine levels, therefore, may affect the density of beta-adrenoceptors in the bulb. In the current study, we test this hypothesis by performing unilateral lesions of the locus coeruleus with 6-hydroxydopamine on postnatal day 4, and examining the density of beta-1- and beta-2-adrenergic receptors in the main olfactory bulb of the rat using 125I-labeled iodopindolol receptor autoradiography on postnatal day 19. Locus coeruleus destruction resulted in a statistically significant increase in the density of adrenergic receptors in the ipsilateral bulb compared to the contralateral bulb. Both beta-1- and beta-2-adrenoceptor subtypes increased in density with this manipulation, although the number of glomerular layer high-density beta-2 foci was not significantly different between the two bulbs. These results are consistent with the hypothesis that changes in olfactory bulb norepinephrine can regulate the density of beta-adrenergic receptors in the bulb.

A learned odor decreases the number of Fos-immunopositive granule cells in the olfactory bulb of young rats.

Olfactory stimulation evokes a column of activity within the olfactory bulb extending from the glomerular layer to the granule cell layer that can be visualized with 2-deoxyglucose autoradiography, optical imaging, Fos protein immunohistochemistry and c-fos mRNA in situ hybridization. The Fos response to odors is typified by the activity of relatively few juxtaglomerular cells, which often occur in foci, and a large number of granule cells extending through much of the bulb. In this study, we characterized the granule cell response to an odor for which young rats had acquired a preference. Fos-like immunoreactive granule cells were quantified by image analysis, and densely stained cells were counted in a region previously shown to be responsive to peppermint odor. We found that odor-trained pups have about half the number of Fos-immunopositive superficial granule cells which respond to a learned odor than do control pups. We then determined whether there was a correlation between the juxtaglomerular cell response and the response of the superficial granule cells deep to those glomerular layer cells. We found a positive correlation between the number of juxtaglomerular cells and the number of granule cells demonstrating Fos immunoreactivity in both control and trained pups, a relationship that changed with early olfactory training.

Synaptophysin-like immunoreactivity in the rat olfactory bulb during postnatal development and after restricted early olfactory experience.

Synaptophysin is a synaptic vesicle protein that provides a marker of synaptic distribution in the brain. We used synaptophysin immunohistochemistry to detect changes in synaptic distribution in the main olfactory bulb during normal early postnatal development and following early olfactory restriction. Synaptophysin-like immunoreactivity appears early in the postnatal development of most bulbar laminae. In the first postnatal week, the entire glomerular neuropil is stained intensely, but by PND 19, the glomerular perimeter becomes more intensely stained than its core. This immunoreactivity is especially dense along that aspect of the perimeter facing the olfactory nerve layer. To determine if this developmental pattern could be affected by early olfactory experience, unilateral naris closure was performed on PND 1. In deprived bulbs at PND 19, the difference in staining between the glomerular border and the glomerular core is significantly less than in either contralateral glomeruli or glomeruli from unoperated animals. The difference between the glomerular border and the glomerular core is greater in bulbs contralateral to a closed naris than in bulbs from unoperated animals. Staining intensity measured over entire glomeruli is not altered by naris closure, nor is staining of other laminae. The changes detected after naris closure indicate that the glomerular distribution of synaptophysin may be particularly sensitive to early olfactory experience.

A learned odor evokes an enhanced Fos-like glomerular response in the olfactory bulb of young rats.

Young rats exposed to peppermint odor and reinforcing tactile stimulation from postnatal days (PND) 1-18 increase their preference for that odor relative to controls. This early olfactory memory is accompanied by an 80% increase in the density of glomerular-layer cells displaying Fos-like immunoreactivity in response to the learned odor on PND 19. The difference is observed in midlateral portions of the olfactory bulb that align with foci of 2-deoxyglucose (2-DG) uptake in adjacent sections. Trained and control animals are not different in the Fos-like response of juxtaglomerular cells within ventrolateral 2-DG foci. Ratios of midlateral/ventrolateral response differ significantly between trained and control animals and include differences among cells of three staining intensities. These ratios are correlated with ratios of 2-DG uptake (midlateral/ventrolateral foci), which also differ significantly between trained and control rats. Juxtaglomerular cells associated with 2-DG foci also express Egr-1-like immunoreactivity. However, the midlateral Egr-1 response does not differ between trained and control rats. These results show that early memories can be associated with an increased Fos-like response in a primary sensory area of the CNS. They also suggest that only specific regions within the olfactory bulb are modified following the learning of a given odor in early life.

Early olfactory enrichment and deprivation both decrease beta-adrenergic receptor density in the main olfactory bulb of the rat.

The density of noradrenergic locus coeruleus projections and beta-adrenergic receptors in the main olfactory bulb of the rat increases with age. Both beta 1- and beta 2-adrenergic receptor subtypes exhibit laminar distributions, with focal regions of high receptor density present within the neuropil of individual glomeruli. Since the first synaptic contacts between olfactory receptor neurons and bulbar neurons occur within the glomeruli, early olfactory experiences possibly could influence the density or distribution of beta-adrenergic receptors in the bulb. We therefore investigated the effects of olfactory deprivation and early olfactory enrichment on the density and distribution of beta-adrenergic receptors in the main olfactory bulb. Animals were subjected to either unilateral naris closure on postnatal day 1 or odor training from postnatal days 1-18. Bulbs were removed on postnatal day 19 and subjected to quantitative autoradiography using the beta-adrenergic receptor antagonist [125I]iodopindolol and specific receptor subtype antagonists ICI 118,551 (beta 2-antagonist) and ICI 89,406 (beta 1-antagonist). Unilateral naris occlusion decreased both the number of beta 2 glomerular foci and the density of beta 1 and beta 2 receptors in the deprived bulb compared to the nondeprived bulb. Early odor training resulted in a significant decrease in the number, area, and receptor density of beta 2 glomerular foci in the midlateral region of the bulb. The distribution of beta 2 glomerular foci also differs with these two sensory manipulations. Changes in beta-adrenergic receptor density in response to both early learning and olfactory deprivation may be induced by a transient increase in olfactory bulb norepinephrine.

Distribution and development of beta-adrenergic receptors in the rat olfactory bulb.

Beta-adrenergic stimulation appears to be involved in the establishment of both learned olfactory preferences and functional changes in the olfactory bulb of young rats. We examined the postnatal development of beta-adrenergic receptors within the main olfactory bulb to determine the density and distribution of these receptors. To quantify beta-adrenergic receptor density, olfactory bulb homogenates from postnatal day (PND) 1, 6, 12, and 19 rats were assessed for receptor binding with 125I-iodopindolol. In addition, receptor autoradiography was performed with the selective beta 1 antagonist ICI 89,406 and selective beta 2 antagonist ICI 118,551 on tissue sections from PND 1-30 rats to examine the distribution of the beta-adrenergic receptor subtypes. We observed both an increase in receptor density with increasing age and the formation of distinct spatial distributions of the two beta receptor subtypes within the bulbar lamina. Beta-adrenergic receptors were located in both deep and superficial layers of the bulb. Specifically, beta 1 receptors were present in the granule cell, internal plexiform and glomerular layers. beta 2 receptors were present in the granule cell, internal plexiform, external plexiform, and glomerular layers. High levels of beta 2 receptors also were visible in the meningeal layers between the two bulbs. High densities of beta 1 and beta 2 adrenergic receptors were present within different sets of individual glomeruli by PND 12-19, and the number of these foci increased with age. The knowledge of beta-noradrenergic receptor localization in the bulb may provide the basis for understanding the action of norepinephrine on neural processes in the developing olfactory bulb.

Post-traumatic myelopathy following flopping high jump: a pilot case of spinal manipulation.

OBJECTIVE: To present the first case of spinal cord injury from high jump and the first pilot case of spinal manipulation for post-traumatic myelopathy. CLINICAL FEATURES: An 11-yr-old tetraplegic boy was admitted to the hospital, where he had a thorough neurological examination, including myelogram, EEG and skull and spinal X rays, with normal findings. The author revealed subtle subluxations on plain X-ray films. Triceps hyperreflexia was detected bilaterally. Bilateral patella and ankle clonus with hyperreflexia, basic and excess spasticity, and bilateral extensor plantar responses were noted in the lower limbs. A clinical diagnosis of early post-traumatic incomplete spastic tetraplegia below C7 was made. INTERVENTION AND OUTCOME: He did not respond to 3 months of orthodox conservative hospital management, including steroid therapy. Spinal manipulation of the lower cervical and upper thoracic spine was performed in a private chiropractic clinic for 2 wk. He apparently recovered after 3 months of spinal manipulation. On recent examination, he has virtually completely recovered. He still suffers from hand muscle atrophy, hyperreflexia of the triceps and ankle reflex and bilateral positive Babinski reflex; ankle and patellar clonus are almost absent. CONCLUSIONS: The early response and long-term (9-yr follow-up) benefits of spinal manipulation to the early delayed traumatic myelopathy of this patient suggest spinal cord ischemia as its pathophysiology. Mechanisms of post-traumatic myelopathy are postulated. Biomechanical mechanisms of spinal manipulation for neurological recovery of post-traumatic myelopathy and/or radiculopathy are advanced. Further pilot spinal manipulation by experienced chiropractors after adequate anti-edematous (steroid) therapy is recommended for selected patients with post-traumatic myelopathy and/or radiculopathy, especially in a multidisciplinary spinal injury unit.

Increase in a focal population of juxtaglomerular cells in the olfactory bulb associated with early learning.

Young rats learn to approach an odor that had been experienced in the presence of reinforcing tactile stimulation. Subsequent presentation of the conditioned odor also evokes an enhanced focal uptake of 2-deoxyglucose (2-DG) in the glomerular layer of the olfactory bulb, and the glomerular-layer width of such foci increases in conditioned pups. In the present study, we determined whether an increase in the glomerular-layer cell population contributes to this structural and functional change. We therefore counted and measured glomerular-layer cells in Nissl-stained sections from focal regions of radiolabeled 2-DG uptake. While cell size did not differ between groups, conditioned pups had a 19% increase in the number of glomerular-layer cells associated with the 2-DG foci compared to controls. The increase in cell number may contribute to the enhanced 2-DG uptake in glomerular-layer foci.

Traumatic spinal myoclonus.

A 24-yr-old woman suffering from traumatic spinal myoclonus which occurred after a diving injury, and which had not responded to pharmacotherapy, apparently resolved after treatment by manipulation of the spine. Mechanisms of the etiology of myoclonus are discussed, and theoretical mechanisms for the use of manipulative procedures in the management of traumatic spinal myoclonus are advanced.

Fracture of the fabella.

A very rare case of traumatic avulsion fracture of the fabella in a middle-age lady, presented as intermittent posterolateral localized knee pain accentuated by compression against the lateral femoral condyle and by active and passive knee extension, is illustrated. The accumulated chronic microtrauma of the osteoarthritic fabello femoral joint in this lady especially during the whip-kick of daily breaststroke swimming for over 30 yr, may precipitate a fabella stress fracture. Radiographs reveal bilateral fabellae with a left bipartite fabella as a stress fracture traversing it without displacement; this later became a completely displaced bipartite avulsion fracture after accidental knee hyperextension. Conservative treatment consisted of anti-inflammatory/analgesic cream, cryotherapy, TENS, strapping and avoiding knee hyperextension.

Traumatic manubriosternal joint subluxations in two basketball players.

Two cases of traumatic manubriosternal joint subluxation without rib fractures in basketball players are illustrated. The incidence of this sport injury is rare. Accidental or intentional violent blows of the elbow to the body of the sternum is the mechanism of this injury. Radiographic analysis of the manubriosternal joint is discussed. Radiographically, the body of the sternum in each case has subluxated posteriorly. The athletes present pain directly at the manubriosternal joint; this may be aggravated by active thoracic hyperflexion or hyperextension. Ordinary or deep breathing does not cause discomfort. Palpation may reveal local tenderness that will be accentuated by ballottement against the manubrium. Conservative treatment consists of manipulative hyperflexion reduction supplemented with antiinflammatory or analgesic cream, cryotherapy, taping or with pad, strapping and rest.

Neurological features of acromegaly: a review and report of two cases.

The neurological features of acromegaly are reviewed and two cases are reported. The most common neurological complications of active hypersomatotropism are headache, acroparesthesia and visual disturbance. Primary peripheral neuropathy, myopathy, entrapment myelopathy and/or cauda equina syndrome are uncommon, especially in young acromegalics. It is postulated that peripheral neuropathy in acromegaly is due to the entrapment of a nerve secondary to a soft tissue edematous mechanism by traumatic compression, angulation and/or stretching of the nerve in acquired extraspinal intermuscular, fibrous or osseofibrous tunnel stenosis; and/or in acquired spinal lateral recess stenosis, rather than true primary neuropathic or secondary endocrinological complications of hypersomatotropism. Proximal weakness is more likely arthropathic rather than myopathic, neuropathic or endocrinologic. Differential diagnosis of backache is briefly discussed. Further investigations of the mechanisms and the conservative treatment for neurological involvements in acromegaly are needed.

Radiological features and diagnosis of acromegaly.

The most constant radiological features of acromegaly include soft tissue hyperplasia, and increased joint spacing, especially in the limbs by articular cartilage overgrowth. Overgrowth is variable in bone. Despite the closure of the epiphysis, articular endochondral overgrowth and subsequent ossification does occur at specific sites as pseudoepiphyseal linear growth. The combined bony apposition-remodeling resorption mechanism, rather than a true osteoporosis, may involve the skull, extremities and spine. Radiological features of the spine have scarcely been reported. The clinical significance of hyperostosis of the spinous process for chronic backache, and vertebral scalloping to compensate for entrapment myelopathy and/or cauda equina syndrome or radiculopathy are overlooked. Further series of radiological assessment of the spine by noninvasive CT scans and plain radiography are recommended. The diagnosis of acromegaly is discussed from a literature review. Deep facial skin-crease testing and dorsal skin-fold assessment of the extremities are recommended as initial screens for evidence of soft tissue hyperplasia.

Postmyelographic cauda equina syndrome in an asymptomatic acquired spinal stenosis of a young acromegalic.

Early postmyelographic cauda equina syndrome in an asymptomatic young acromegalic is presented. The patient was asymptomatic for more than 1 yr despite myelographic evidence of acquired spinal stenosis at the L2-L4 level. Radiographic and/or myelographic findings should be clinically correlated. It is postulated that, in acromegaly, the combined simultaneous bony apposition-remodeling resorption mechanism is involved in the spine as platyspondyly, hyperostosis of spinous processes and vertebral scalloping to counteract soft tissue hyperplasia within the spinal canal; entrapment myelopathy, cauda equina syndrome and/or radiculopathy are ascribed to a soft tissue edematous mechanism superimposed on congenital or degenerative spinal stenosis, traumatic or postoperative spondylolisthesis, postmyelographic and/or postoperative arachnoiditis and a traumatic swollen or protrused intervertebral disc.

Traumatic volar dislocation of the second, third and fourth carpometacarpal joints: mechanism and manipulation.

Traumatic volar dislocation of the second, third and fourth carpometacarpal joints without associated fracture is extremely rare. A single case, treated successfully by manipulative reduction supplemented with splint immobilization and isometric and isotonic muscle exercise is reported, with restoration of complete anatomical alignment revealed by postmanipulative radiographs. The radiology of carpometacarpal joint dislocation is discussed. The conservative traction-dorsiflexion manipulative reduction for multiple volar carpometacarpal joint dislocations is described and recommended before using open reduction. Based on the case, it is postulated that the mechanism of a carpometacarpal joint dislocation is due to a sudden violent force acting almost perpendicularly to the metacarpal head or heads; the reactive forces create the opposite directed forces as a lever type of strain on the involved carpometacarpal joint and produce the dislocation.