Aggregation of actin and cofilin in identical twins with juvenile-onset dystonia

The neuropathology of the primary dystonias is not well understood. We examined brains from identical twins with DYT1-negative, dopa-unresponsive dystonia. The twins exhibited mild developmental delays until age 12 years when they began developing rapidly progressive generalized dystonia. Genetic, metabolic, and imaging studies ruled out known causes of dystonia. Cognition was subnormal but stable until the last few years. Death occurred at ages 21 and 22 years. The brains were macroscopically unremarkable. Microscopic examination showed unusual glial fibrillary acidic protein-immunoreactive astrocytes in multiple regions and iron accumulation in pallidal and nigral neurons. However, the most striking findings were 1) eosinophilic, rod-like cytoplasmic inclusions in neocortical and thalamic neurons that were actin depolymerizing factor/cofilin-immunoreactive but only rarely actin-positive; and 2) abundant eosinophilic spherical structures in the striatum that were strongly actin- and actin depolymerizing factor/cofilin-positive. Electron microscopy suggested that these structures represent degenerating neurons and processes; the accumulating filaments had the same dimensions as actin microfilaments. To our knowledge, aggregation of actin has not been reported previously as the predominant feature in any neurodegenerative disease. Thus, our findings may shed light on a novel neuropathological change associated with dystonia that may represent a new degenerative mechanism involving actin, a ubiquitous constituent of the cytoskeletal system.

Evaluation of the microvasculature and cerebral ischemia after experimental subarachnoid hemorrhage in dogs

OBJECT

Whether cerebral vasospasm occurs only in surface vessels or also in parenchymal arterioles is debatable. The present study was undertaken to evaluate comprehensively the microvasculature of the brainstem after experimental subarachnoid hemorrhage (SAH).

METHODS

Nine mongrel dogs of either sex, each weighing between 18 and 24 kg, underwent double blood injections spaced 48 hours apart; the injections were infused into the cisterna magna immediately after angiography of the basilar arteries (BAs). Three additional dogs assigned to a control group received no blood injections. The dogs were killed on Day 7. Axial sections obtained from the midpontine region of both control dogs and animals subjected to SAH were evaluated with respect to the morphological characteristics of vessels and neurons, and for ultrastructural changes. Severe vasospasm occurred in the BAs of all dogs subjected to SAH. Nevertheless, in these animals, the luminal areas and vessel perimeter in parenchymal arterioles, but not in parenchymal venules, were observed to have increased when compared with those of control dogs (p < 0.01, t-test). No corrugation of the internal elastic lamina was observed and smooth-muscle and endothelial cells remained normal at the ultrastructural level in the dogs with SAH.

CONCLUSIONS

In this model, vasospasm of the BAs did not extend into the region of the pons to affect the intraparenchymal arterioles. Dilation of the parenchymal arterioles might serve as compensation for reduced blood flow. Thus, no neuronal ischemia or infarction resulted in the pontine region of the brain.

Vacuolar lesion profile in sheep scrapie: factors influencing its variation and relationship to disease-specific PrP accumulation

Detailed neuropathological examination for vacuolar lesions was performed on the brains of 42 sheep with clinical signs compatible with scrapie. The sheep were grouped according to their breed (Poll-Dorset, Cheviot, Welsh Mountain, Shetland and Suffolk), their PrP genotype at codons 136, 154 and 171 (VRQ/VRQ, VRQ/ARQ, VRQ/ARR and ARQ/ARQ) and the type of infection (experimental infection with SSBP/1, or natural disease). Twenty-two neuroanatomical sites from seven brain regions were examined for vacuolation in the neuropil and five sites at the level of the obex were examined for intraneuronal vacuolation. In 36 sheep, immunohistochemical examination for disease-specific PrP (PrP(d)) accumulation had also been performed in the same brain regions in an earlier study. The magnitude of total neuropil vacuolation was highest in the naturally affected ARQ/ARQ Suffolk sheep and lowest in the experimentally infected VRQ/VRQ Cheviot sheep and VRQ/ARR Poll-Dorset sheep. The severity of neuropil vacuolation at nine of the 22 neuroanatomical sites examined was used to generate a vacuolar lesion profile, which showed variations between the different sheep groups. These variations could be attributed to both PrP genotype and sheep breed and also possibly to scrapie agent; there was, however, considerable individual variation in lesion profile within sheep groups. All groups showed a similar ratio of neuropil vacuolation to neuronal vacuolation at the level of the obex. Although a positive correlation between neuropil vacuolation and PrP(d) deposition was generally observed, it was low except for the astrocyte-associated pattern of PrP(d) accumulation. The study suggests that vacuolar lesion profiles in sheep are affected by several factors and, by comparison with lesion profiles in mice, are of no more than limited value for discriminating between scrapie strains.

Ballooned neurons in progressive supranuclear palsy are usually due to concurrent argyrophilic grain disease

Progressive supranuclear palsy (PSP) is a sporadic multisystem neurodegenerative disorder that is one of the major causes of parkinsonism, which shares common biochemical and genetic features with corticobasal degeneration (CBD). Ballooned neurons (BN) are one of the histopathologic hallmarks of CBD and their presence is a neuropathologic feature that helps differentiate PSP from CBD, since BN are uncommon in PSP. There are, however, several reports in the literature of BN in PSP. BN are also a consistent finding in argyrophilic grain disease (AGD), where they are relatively confined to limbic structures, in particular the amygdala. Since AGD has been found with increased frequency in PSP, it is possible that cases of PSP with BN may represent co-existing AGD. In the present study, we investigated this possibility by studying the distribution and the density of BN with alphaB-crystallin immunostaining in 20 cases of PSP, including equal numbers of cases with and without co-existing AGD. In PSP cases with concurrent AGD, BN were consistently found in limbic areas, but in pure PSP cases, BN were rare, supporting the hypothesis that concurrent AGD may account for most cases of PSP with BN.

The intralaminar nuclei assigned to the medial pain system and other components of this system are early and progressively affected by the Alzheimer's disease-related cytoskeletal pathology

The intralaminar nuclei of the human thalamus are integrated into the ascending reticular activating system and into limbic, oculomotor and somatomotor loops. In addition, some of them also represent important components of the medial pain system. We examined the occurrence and severity of the Alzheimer's disease (AD)-related cytoskeletal pathology and beta-amyloidosis in the seven intralaminar nuclei (central lateral nucleus, CL; central medial nucleus, CEM; centromedian nucleus, CM; cucullar nucleus, CU; paracentral nucleus, PC; parafascicular nucleus, PF; subparafascicular nucleus, SPF) in 27 autopsy cases at different stages of the cortical neurofibrillary pathology (cortical NFT/NT-stages I-VI) and beta-amyloidosis (cortical phases 1-4). The CEM, CL, PF, and SPF are slightly affected at stage II (corresponding to preclinical AD). They are markedly involved at stages III and IV (i.e. incipient AD) and severely affected at stages V and VI (i.e. clinical AD). In the PC and CU, the cytoskeletal pathology is mild at stage III, marked at stage IV, and severe at stages V-VI, whereas the CM is only mildly affected at stages IV-VI. In all of the intralaminar nuclei, deposits of the protein beta-amyloid occur for the first time during the final phase of cortical beta-amyloidosis. Functionally, the cytoskeletal pathology encountered in the intralaminar nuclei may contribute to the memory and affective symptoms, attention deficits, and dysfunctions related to horizontal saccades and smooth pursuits seen in AD patients. Equally important, however, are the findings that the cytoskeletal pathology developing within the intralaminar nuclei assigned to the medial pain system (CEM, CL, CU, PC, PF) as well as within other components of this system begins already during the preclinical or incipient phases of AD. Given this fact, the question arises as to whether non-discriminative aspects mediated by the medial pain system could be employed to identify individuals in the very earliest stages of AD.

Alpha-synuclein-immunoreactive deposits in human and animal prion diseases

Prion related disorders are associated with the accumulation of a misfolded isoform (PrPsc) of the host-encoded prion protein, PrP. There is strong evidence for the involvement of unidentified co-factors in the PrP to PrPsc conversion process. In this study, we show alpha-synuclein-immunoreactive deposits in the central nervous system of various prion diseases (sporadic, iatrogenic and new variant Creutzfeldt-Jakob diseases, and experimental scrapie of hamsters). alpha-Synuclein accumulated close to PrPsc deposits but we did not observe strict colocalization of prion protein and alpha-synuclein immunoreactivities particularly in PrPsc plaques. alpha-Synuclein is thought to be a key player in some neurodegenerative disorders, is able to interact with amyloid structures and has known chaperone-like activities. Our results, in various prion diseases, suggest a role for alpha-synuclein in regulating PrPsc formation.

Severe involvement of the ambient gyrus in a case of dementia with argyrophilic grain disease

We report here the severe involvement of the ambient gyrus in a case of argyrophilic grain (AG) dementia (AGD). The patient was a 78-year-old man who was first presented with prosopagnosia (agnosia of the face) at age 68, which was followed by progressive mental decline and the patient's death in a state of tetraplegia. The postmortem study showed severe atrophy of the medial temporal lobe with anterior gradient, most prominent in the ambient gyrus. Histologically, numerous AGs, pretangles and coiled bodies were detected by Gallyas-Braak (G-B) silver staining and also by immunostaining with various anti-tau antibodies in the affected area. Tau-immunoreactive ballooned neurons were also present. Neuronal loss and gliosis with laminar sponginess were evident in the ambient gyrus. Diffuse plaques were seen in the neocortex and frequently associated with clusters of AGs, which were morphologically distinct from neuritic plaques. Neurofibrillary tangles were localized in the entorhinal area. Vascular lesions were very scanty. Thus, this case fulfilled the morphological criteria of AGD. It is still unclear whether AG itself causes neuronal degeneration leading to dementia. The present case may reflect the importance of the ambient gyrus in the center of neuronal degeneration in AGD.

Inherited frontotemporal dementia in nine British families associated with intronic mutations in the tau gene

Genetic screening of 171 patients with frontotemporal lobar degeneration disclosed 14 patients, across nine pedigrees, with mutations in the intron to exon 10 in the tau gene, a region regulating the splicing of exon 10 via a stem loop mechanism. Thirteen of these patients had the +16 splice site mutation and one had the +13 splice site mutation. Affected members of all nine families presented with changes in behaviour and social conduct that were prototypical of frontotemporal dementia (FTD). In all patients with the +16 splice site mutation, the behavioural profile was characterized by disinhibition, restless overactivity, a fatuous affect, puerile behaviour and verbal and motor stereotypies. The single patient with the +13 mutation presented a contrasting picture of apathy and inertia. In addition, all patients had evidence of semantic loss. Pathologically, five of the six patients so far autopsied shared frontotemporal atrophy with involvement of the substantia nigra. The underlying histology was that of microvacuolar-type cortical degeneration with a few swollen cells. Tau pathology was widespread throughout the brain and present in neurones and glial cells, mostly in the frontal and temporal cortical regions. This was in the form of neurofibrillary tangles and amorphous tau deposits (pre-tangles); Pick bodies were not observed. Ultrastructurally, the tau filaments had a twisted, ribbon-like morphology distinct from the paired helical filaments of Alzheimer's disease. One patient died from an unrelated illness whilst in the early clinical stages of FTD. In this patient, cortical microvacuolar and astrocytic changes were absent, though there were scattered neurones and glial cells, immunoreactive to tau, throughout the cortical and subcortical regions. The disease process underlying the neurodegeneration within these inherited forms of FTD may therefore stem directly from early, primary alterations in the function of tau. All eight families with the +16 mutation seem to be part of a common extended pedigree, possibly originating from a founder member residing within the North Wales region of Great Britain.

Minicolumnar pathology in autism

OBJECTIVE

To determine whether differences exist in the configuration of minicolumns between the brains of autistic and control patients.

BACKGROUND

Autism is a severe and pervasive developmental disturbance of childhood characterized by disturbances in both social interactions and communication, as well as stereotyped patterns of interests, activities, and behaviors. Postmortem neuropathologic studies remain inconclusive.

METHODS

The authors used a computerized imaging program to measure details of cell column morphologic features in area 9 of the prefrontal cortex and areas 21 and posterior 22 (Tpt) within the temporal lobe of nine brains of autistic patients and controls.

RESULTS

The authors found significant differences between brains of autistic patients and controls in the number of minicolumns, in the horizontal spacing that separates cell columns, and in their internal structure, that is, relative dispersion of cells. Specifically, cell columns in brains of autistic patients were more numerous, smaller, and less compact in their cellular configuration with reduced neuropil space in the periphery.

CONCLUSIONS

In autism, there are minicolumnar abnormalities in the frontal and temporal lobes of the brain.

Perisomatic granules (non-plaque dystrophic dendrites) of hippocampal CA1 neurons in Alzheimer's disease and Pick's disease: a lesion distinct from granulovacuolar degeneration

A number of pathological changes have been reported in relation to CA1 pyramidal cells in Alzheimer's disease (AD), among them hyperphosphorylation of tau protein followed by the formation of filamentous tau lesions, granulovacuolar degeneration (GVD), Hirano bodies and spindle-shaped dilatations of distal apical dendrites. Juxtacellular clusters of glutamate receptor (GluR)-positive granules around pyramidal cells of the CA1 sector have been recently reported under the term "non-plaque dystrophic dendrites". We independently found that CA1 pyramidal cells in AD patients are regularly surrounded by ubiquitin-positive granules measuring 1-4 microns in diameter, which we have termed perisomatic granules (PSG). Using confocal microscopy, ubiquitin- and GluR-reactive granules were found to largely coincide and to correspond to the same structure. By immunoelectron microscopy PSG were found to consist of GluR1-2-reactive enlarged synaptic boutons containing tubulo-filamentous or floccular material. PSG were found to be consistently associated with pyramidal (principal) cells but not with interneurons of the CA1 sector. Dual-labeling experiments have shown that PSG are preferentially associated with tau-immunoreactive "pretangle" neurons but not with cells containing filamentous tau inclusions or with tau-negative nerve cell bodies. The number of PSG was found to increase with the severity of AD changes with almost no PSG found in Braak stages I and II and few in stage III. Furthermore, PSG were not AD specific, as shown by their presence around CA1 pyramidal cells in Pick's disease. The reasons for GluR reactivity and ubiquitin complex formation in enlarged perisomatic boutons are unclear. Marked changes in GluR subunits have been observed in association with even moderate AD pathology in hippocampal pyramidal cells in AD and our findings suggest a pathogenic link between PSG and early tau pathology in CA1 neurons. PSG might represent residual and abnormally clustered GluR subunits in degenerating perisomatic neurites. Our work confirms and extend previous study on perisomatic "non-plaque dystrophic dendrites" in AD and establish PSG as a pathological entity distinct from GVD. In addition PSG should be acknowledged among main histological changes associated with hippocampal neurons in AD and Pick's disease.

Rats expressing human cytosolic copper-zinc superoxide dismutase transgenes with amyotrophic lateral sclerosis: associated mutations develop motor neuron disease

Some cases of familial amyotrophic lateral sclerosis (ALS) are caused by mutations in the gene encoding cytosolic, copper-zinc superoxide dismutase (SOD1). We report here that rats that express a human SOD1 transgene with two different ALS-associated mutations (G93A and H46R) develop striking motor neuron degeneration and paralysis. As in the human disease and transgenic ALS mice, pathological analysis demonstrates selective loss of motor neurons in the spinal cords of these transgenic rats. In spinal cord tissues, this is accompanied by activation of apoptotic genes known to be activated by mutant SOD1 protein in vitro and in vivo. These animals provide additional support for the proposition that motor neuron death in SOD1-related ALS reflects one or more acquired, neurotoxic properties of the mutant SOD1 protein. The larger size of this rat model as compared with the ALS mice will facilitate studies involving manipulations of spinal fluid (implantation of intrathecal catheters for chronic therapeutic studies; CSF sampling) and spinal cord (e.g., direct administration of viral- and cell-mediated therapies).

Ubiquitinated granular structures and initial neurofibrillary changes in the human brain

Ubiquitin-positive dots and granular structures from insular, temporopolar, hippocampal and parahippocampal cortices of nondemented and Alzheimer's disease patients have been studied with both light and electron microscopes. The relationship of both types of ubiquitin-positive elements with pretangle neurons and neurofibrillary tangles has been analyzed by comparing adjacent or nearly adjacent sections immunostained for either ubiquitin or an antibody that recognizes hyperphosphorylated tau protein (AT-8). Moreover, a double protocol with both antibodies was used in order to obtain double-stained sections. The presence of ubiquitin-positive dots and granular structures precedes the appearance of pretangle neurons in the youngest cases. In aged and Alzheimer disease cases, both types of ubiquitin-positive elements decrease in number as pretangle neurons are replaced by mature and ghost tangles. Ultrastructurally, dots and granular structures appear to be degenerating neuronal processes and/or terminals. Our results suggest that the degeneration of these processes and/or terminals might be related with the initiation of neurofibrillary degeneration.

Huntingtin aggregate-associated axonal degeneration is an early pathological event in Huntington's disease mice

Huntington's disease (HD) is characterized by the selective loss of striatal projection neurons. In early stages of HD, neurodegeneration preferentially occurs in the lateral globus pallidus (LGP) and substantia nigra (SN), two regions in which the axons of striatal neurons terminate. Here we report that in mice expressing full-length mutant huntingtin and modeling early stages of HD, neuropil aggregates form preferentially in the LGP and SN. The progressive formation of these neuropil aggregates follows intranuclear accumulation of mutant huntingtin and becomes prominent from 11 to 27 months after birth. Neuropil aggregates, but no intranuclear inclusions, were observed in the LGP and SN, suggesting that huntingtin aggregates are formed in the axons of striatal projection neurons. In the LGP and SN, we observed degenerated axons in which huntingtin aggregates were associated with dark, swollen organelles that resemble degenerated mitochondria. Neuritic aggregates also form in cultured striatal neurons expressing mutant huntingtin, block protein transport in neurites, and cause neuritic degeneration before nuclear DNA fragmentation occurs. These findings suggest that the early neuropathology of HD originates from axonal dysfunction and degeneration associated with huntingtin aggregates.

Alpha-synuclein has an altered conformation and shows a tight intermolecular interaction with ubiquitin in Lewy bodies

Alpha-synuclein, a protein in which two mutations have been identified that cause autosomal dominant Parkinson's disease, is thought to serve as a nidus for the development of a Lewy body. We hypothesized that alpha-synuclein would display different intra- and intermolecular associations in Lewy bodies than it does in its normal intracellular compartments. Using sensitive fluorescence resonance energy transfer (FRET) techniques, we found evidence that alpha-synuclein is more compact and in closer association with other alpha-synuclein molecules in Lewy bodies than it is in the neuropil. In addition, we found evidence of a close, direct intermolecular interaction between the N terminus of alpha-synuclein and ubiquitin. These observations provide support for the hypothesis that in Lewy bodies alpha-synuclein adopts an altered three-dimensional structure and undergoes N-terminal ubiquitination.

Senile plaques exert no mass lesion effect on surrounding neurons

Since the turn of the century studies have suggested that clinical deterioration in Alzheimer's disease (AD) is accompanied by a gradual increase in both the size and numbers of senile plaques (SP's). Our study investigated the 'mass effect' of SP's on the morphometry of adjacent neurons. For this purpose, we used a computerized image analysis system to study pyramidal cells from the hippocampus of ten AD patients, ten demented schizophrenic (SC) patients and ten cognitively impaired non-AD/non-SC control patients with. We examined cell shape, area and disarray and quantitated the number of SP's and neurofibrillary tangles (NFT's) in the CA1 subfield of the hippocampus. Our results indicated no significant differences between groups for measurements of neuronal shape, size, or disarray. Contrary to earlier reports, our results noted no evidence of pyramidal cell disarray in schizophrenic patients. Our results suggest that SP's incorporate, rather than displace, their surrounding neuropil.

Regional variations in the apparent diffusion coefficient and the intracellular distribution of water in rat brain during acute focal ischemia

BACKGROUND AND PURPOSE

The apparent diffusion coefficient of water (ADC) rapidly drops in ischemic tissue after cerebral artery occlusion. This acute drop is thought to be caused by the loss of extracellular fluid and the gain of intracellular fluid. To test the latter possibility, changes in ADC and the size of several cellular compartments were assessed in 3 regions of rat brain at the end of 90 minutes of focal cerebral ischemia.

METHODS

One middle cerebral artery was permanently occluded in 8 Sprague-Dawley rats; sham occlusions were performed in 2 other rats. ADC maps were generated 90 minutes later, and the brains were immediately perfusion fixed. Three regions of interest (ROIs) were defined on the basis of ADC range. Various neuronal, astrocytic, and capillary compartments in each ROI were quantified with light and electron microscopy.

RESULTS

At the end of 90 minutes of ischemia, mean ADC was normal in the cortex of sham-operated rats and the contralateral cortex of ischemic rats (ROI-a), 25% lower in the ipsilateral frontoparietal cortex (ROI-b), and 45% lower in the ischemic lateral caudoputamen (ROI-c). At this time, the frequency of swollen astrocytic cell bodies and volume of swollen dendrites and astrocytic processes in neuropil were ROI-a<ROI-b<ROI-c. In ROI-b and ROI-c, 40% and 60% of the neurons, respectively, were shrunken; the shrunken neurons were approximately 25% smaller in ROI-c than in ROI-b. In these areas, many capillary endothelial cells, pericytes, and perivascular foot processes were swollen.

CONCLUSIONS

The initial lowering of ADC during focal ischemia probably is the result of not only the acute loss of extracellular fluid and concomitant swelling of various cellular compartments but also concurrent neuronal shrinkage.

Radiosurgery-induced microvascular alterations precede necrosis of the brain neuropil

OBJECTIVE

Radiosurgery is used as a therapeutic modality for a wide range of cerebral disorders. It is important to understand the underlying causes of deleterious side effects that may accompany gamma-irradiation of brain tissue. In this study, structural alterations in rat cerebral vessels subjected to gamma knife irradiation in vivo were examined, for elucidation of their potential role in necrosis formation.

METHODS

A maximal center dose of 75 Gy was delivered to the rat parietal cortex with a 4-mm collimator, and changes occurring before necrosis formation were assessed 3.5 months after irradiation. Transmission electron microscopy, using horseradish peroxidase as a tracer, and scanning electron microscopy with vascular casting were performed.

RESULTS

The capillary network in the irradiated area exhibited thickening and vacuolation of the basement membrane. The capillary density in the irradiated area was lower and the average capillary diameter was larger, compared with the nonirradiated side. These results indicate that substantial changes in the neuropil do not occur 2 weeks before the time of definite necrosis formation, whereas changes in the basement membrane are prominent.

CONCLUSION

The necrotic response to intermediate doses of focused-beam irradiation appears after a considerable latency period and then progresses rapidly. This contrasts with previously reported responses to fractionated whole-brain irradiation, in which damage occurs slowly and gradually. Alterations in the microvascular basement membrane precede overt cellular changes in neuronal and vascular cells and provide an early index of cerebrovascular dysfunction in regions destined to undergo necrosis.

Argyrophilic grain disease mimicking temporal Pick's disease: a clinical, radiological, and pathological study of an autopsy case with a clinical course of 15 years

This report concerns an autopsy case of argyrophilic grain disease (AGD) mimicking temporal Pick's disease. The patient was a Japanese woman without hereditary burden who was 89 years old at the time of death. She developed memory impairment and began wandering at the age of 74, followed by prominent character changes about 6 years after disease onset. A neurological examination 5 months before her death revealed poor rapport, unconcern, severe dementia, and double incontinence, without aphasia or muscle rigidity. Serial neuroradiological examination revealed progressive enlargement of the bilateral inferior horns of the lateral ventricle, reflecting progressive atrophy of the medial temporal lobes. Macroscopically, neuropathological examination showed circumscribed atrophy of the bilateral amygdalae, hippocampi, parahippocampal gyri, and lateral occipitotemporal gyri. Histologically, there was neuronal loss in the areas mentioned above, the caudate nucleus, putamen, thalamus, substantia nigra, and locus ceruleus, with ballooned neurons in the cerebral cortex and amygdala. Numerous argyrophilic grains with coiled bodies were present not only in the limbic system, but also in the affected cerebrum. Rare neurofibrillary changes were present in the limbic areas, consistent with Braak stage II, with no senile plaques. Based on these findings and a review of the literature, we note that AGD is clinicopathologically similar not only to mesolimbocortical dementia, but also to atypical senile dementia of Alzheimer type. This report may contribute to the elucidation of the clinicopathological hallmarks of AGD.

Tau-associated neuropathology in ganglion cell tumours increases with patient age but appears unrelated to ApoE genotype

Ganglion cell tumours, including gangliogliomas and gangliocytomas, are low grade neoplasms with a mature neuronal component. Ganglion cells within these lesions occasionally exhibit neurodegenerative changes including neurofibrillary tangles (NFT) similar to those in Alzheimer's disease. The frequency and spectrum of degenerative pathology in these lesions have not been defined, nor has their relation to patient age or factors such as apolipoprotein E (ApoE) genotype that predispose to Alzheimer's disease. We studied 72 ganglion cell tumours (61 gangliogliomas, 11 gangliocytomas) from patients 7 months to 72-years-old. Haematoxylin and eosin (H&E), silver stains (Hirano method) and immunohistochemistry for tau, alpha-synuclein and beta-amyloid were performed on formalin-fixed, paraffin-embedded tissue from surgical specimens. Tau-and silver-positive NFT and neuropil threads (NPT) were present in four of 26 ganglion cell tumours from patients over 30-years-old (ages 31, 38, 50, and 58 years). Neuronal granulovacuolar degeneration (GVD) was noted in five of 26 tumours from patients over 30-years-old (mean, 48 years). NFT, NPT, and GVD were not seen in ganglion cell tumours from patients under 30-years-old[0/46]. Cytoplasmic argentophilic bodies distinct from NFT were present in five of 26 tumours from patients over 30-years-old and in two of 46 under 30 years. Neither alpha-synuclein positive neuronal inclusions nor beta-amyloid immunoreactivity was noted in ganglion cell tumours from any age group. The distribution of ApoE genotypes was similar among those tumours that contained tau-associated neuropathology and those that did not. Neurodegenerative changes are uncommon in ganglion cell tumours, but increase in frequency with patient age. GVD, tau-positive NFT and NPT, and argentophilic bodies occur more often in ganglion cell tumours from patients over 30-yrs-old, but do not appear to be associated with a specific ApoE genotype.

Aluminum enhances glutamate-mediated neurotoxicity in organotypic cultures of rat hippocampus

Both, glutamate (GLU) and aluminum (Al) have been implicated in neuronal damage and/or death in certain human neurodegenerative disorders. Recent evidence suggests that aluminum (Al) may potentiate the increase in glutamate-induced intracellular calcium overload. The present ultrastructural study was undertaken to determine the effect of Al on the development of GLU-mediated neurotoxicity in tissue culture conditions. The experiments were performed on organotypic cultures of rat hippocampus treated with low, subtoxic concentration of GLU (50 microM) and AlCl3 (400 microM) added to the growth medium separately or in combination. The exposure of cultures to GLU in the presence of Al3+ ions for up to 24 hours resulted in the development of typical excitotoxic neuronal changes, whereas separate GLU treatment at subtoxic doses or single Al application did not produce any apparent tissue damage. The neuronal lesions resulting from the combined application of GLU plus Al consisted predominately of more or less pronounced mitochondrial abnormalities, which are characteristic for early excitotoxic events. Severe swelling of the mitochondria led to the disruption of their internal structure and finally resulted in an apparent microvacuolization of the perikaryal cytoplasm of some pyramidal neurons. The present morphological data evidenced that Al is capable to potentiate the GLU-induced degenerative changes in hippocampal neurons in vitro. This supports the view of a possible role of Al in the process of neurodegeneration and suggests that Al may participate in the development of glutamate-mediated excitotoxic neuronal injury under certain pathological conditions.

Effects of sensory deprivation on the development of asymmetrical synapses in mouse barrels

Alterations in the numerical density and structure of asymmetrical synapses were examined in thin sections through barrel D4 in six CD/1 mice, including three controls and three sensory deprived animals. Sensory deprivation was effected by once daily trimming of all large mystacial vibrissae on the contralateral side of the snout from P0. The mice were perfuse-fixed at P20, several days following the termination of rapid synaptic growth during barrel development (White et al., Somatosens Mot Res 14: 34-55, 1997). Cerebral hemispheres contralateral to the deprived side were osmicated, sectioned at 40 microm and embedded in plastic for thin sectioning. Sterio's (J Microsc 134: 127-136, 1984) procedure combined with serial thin section analysis (Braendgaard and Gundersen, J Neurosci Meth 18: 39-78, 1986), was applied blindly to systematic random samples of neuropil in barrel hollows and septa. No significant difference in the numerical density, estimated total number, or in the proportion of perforated postsynaptic densities was observed. However, a significant decrease in the diameters of asymmetrical postsynaptic densities was observed in hollow (P < 0.05) and septal (P < 0.05) neuropil of deprived animals. These results demonstrate a significant morphological alteration in asymmetrical synapses of a type consistent with a reduction in synaptic activity consequent to sensory deprivation.

The effects of aging on layer 1 of primary visual cortex in the rhesus monkey

The effect of age on layer 1 in primary visual cortex was determined in 19 rhesus monkeys of various ages. Twelve of the monkeys had been behaviorally tested. With age layer 1 becomes thinner and the glial limiting membrane becomes thicker. In the neuropil of layer 1 many of the dendrites in old monkeys appear to be degenerating and, as a consequence, electron micrographs from old monkeys display fewer dendritic and spine profiles per unit area than in young monkeys. As determined using both the disector and size-frequency methods, there is also a concomitant decrease in the numerical density of synapses with age. Although there is a significant correlation between the thinning of layer 1 in area 17 and age, there is no significant correlation between either the thinning of layer 1 or its loss of synapses and any of the behavioral measures of memory function obtained from the 12 behaviorally tested monkeys. Similar morphological changes with age occur in layer 1 of prefrontal cortex of these same monkeys, but in area 46 both the thinning of layer 1 and the loss of synapses show a significant correlation with behavioral measures of memory function. These differences between layer 1 in these two cortical areas presumably relate to the fact that prefrontal cortex has a greater role in subserving cognition than does primary visual cortex.

The evolution of Alzheimer's disease-related cytoskeletal pathology in the human raphe nuclei

The cross-sectional analyses currently available show that the Alzheimer's disease (AD)-related cytoskeletal alterations within the human brain affect variously susceptible areas of the cerebral cortex in a uniform sequence with very little interpatient variability. This sequence has been divided for research and comparative purposes into six stages (cortical NFT/NT-stages I-VI). Among the subcortical nuclei affected in AD are those belonging to the raphe system. Efforts were focused on the lesions present in these nuclei to see in which of the six stages the AD-related cytoskeletal anomalies begin and whether a correlation exists between the AD-related pathology developing within the cerebral cortex and the cytoskeletal damage that occurs in the nuclei of the raphe system. To this end, serial sections from the brainstems of 27 post-mortem cases with stages I-VI of cortical cytoskeletal lesions were examined. The cytoskeletal pathology was visualized using the modified silver iodide-Gallyas staining technique and the antibody AT8. The latter is directed specifically against the abnormally phosphorylated cytoskeletal protein tau. The dorsal raphe nucleus manifests the cytoskeletal lesions early on (stages I-II). The central and linear raphe nuclei, by contrast, do so initially in stages III-IV, and the caudal raphe nuclei register the first changes in stages V-VI. In stages V and VI, the dorsal raphe nucleus displays the most severe cytoskeletal pathology within the raphe system, followed by the central and linear raphe nuclei, whereas the cytoskeletal anomalies in the caudal raphe nuclei are slight. The developing damage within the nuclei of the raphe system correlates with the stages I-VI and, furthermore, progresses in the oral raphe nuclei in close connection with the evolution of the pathological process in cortical projection destinations of these nuclei. As the source of the ascending serotonergic system, the involvement of the oral raphe nuclei may be partially responsible for the early manifestation of the non-cognitive and emotional deficiencies possibly traceable to dysfunctions within the ascending serotonergic system.

Clinical aspects of argyrophilic grain disease

Argyrophilic grain disease (AGD) is a dementia in the senium characterized by limbic involvement in the form of massive occurrence of argyrophilic and tau-positive grains in the neuropil. The main affected areas in the limbic system are the hippocampal as well as entorhinal regions, and subsequently the amygdaloid nucleus, where mild to moderate degrees of tissue degeneration are also often observed. Retrospective evaluation of 4 patients with AGD revealed common clinical features which consist of memory disturbance, relatively preserved cognitive function and personality change characterized by emotional disorder with aggression or ill temper. Such clinical characteristics are consistent with limbic involvement, and therefore AGD is thought to be a type of limbic dementia. The lack of Klüver-Bucy syndrome, which constitutes the basic part of limbic dementia, may indicate chronic, progressive and mild degeneration in the limbic areas in this disease.

Abnormal neuronal and glial argyrophilic fibrillary structures in the brain of an aged albino cynomolgus monkey (Macaca fascicularis)

An aged albino male cynomolgus monkey (Macaca fascicularis) more than 35 years old died after showing neurological signs including gait disturbance, trembling, drowsing tendency and a decrease in activity. Neuropathological examination revealed glial fibrillary tangles (GFTs) mainly distributed in the putamen, caudate nucleus, thalamic nuclei, substantia nigra, red nucleus, globus pallidus, trapezoid body, pyramid, pons and medulla oblongata of the brain, and neurofibrillary tangles (NFTs) in the thalamic nuclei. These structures were positively stained by the modified Gallyas-Braak (GB) method and immunostained for tau. The tau-positive argyrophilic GFTs were morphologically classified into four types, as in human cases, i.e., tufts of abnormal fibers (TAFs), thornshaped astrocytes (TSAs), glial coiled bodies (GCBs) and argyrophilic threads (ATs) depending on their GB profiles, and GCBs were the major structures in this case. Some of these structures were also immunoreactive for alpha-synuclein. The glial cells possessing the structures were negative for glial fibrillary acidic protein, a marker for astrocytes, indicating that the argyrophilic GFTs were present in oligodendroglia. In addition, marked neuronal loss and ubiquitin-positive spheroid bodies were observed in the substantia nigra and globus pallidus. According to the characteristic distribution of the argyrophilic structures in neurons and glial cells as well as clinical signs, the monkey might have suffered from a neurodegenerative disease such as progressive supranuclear palsy (PSP). This is the first report of the occurrence of a neurodegenerative disease in a nonhuman animal.