bluuebunny/crossref_metadata_2025 huggingface dataset:
Spread of malignant lymphoid cells into rat central nervous system with intact and disrupted blood–brain barrier
Authors: Aho R. , Vaittinen S. , Jahnukainen K. , Kalimo H.
Published: May 2008

The pathways of spread of malignant lymphoid cells into the central nervous system (CNS) were studied using a T lymphoblastic leukaemia/lymphoma model of inbred PVG rats. The effects of intraperitoneal, intracarotid, intravenous, intrathecal and intracerebral routes of transplantation were analysed, and the significance of the blood–brain barrier (BBB) in preventing neoplastic cell invasion was studied by disrupting the BBB with focal cold injury. Extraneurally transplanted cells appeared first in the dura and subarachnoid space. From the latter they spread further into the perivascular space of penetrating cortical vessels. Parenchymal tumour cell foci were only seen in terminally ill rats, usually associated with damage to the vessel wall. Intrathecal transplantation did not accelerate the progression of the disease. Intracerebrally transplanted cells readily produced parenchymal infiltrates with diffuse invasion into the white matter, perivascular spreading into the cortex, and contralateral extension along the corpus callosum. Parenchymal invasion did not occur immediately after disruption of the BBB, but in the chronic phase neoplastic cells infiltrated the injured area. In conclusion, the model closely resembles human CNS leukaemia. Malignant cells appeared to enter the CNS through the deficient BBB of the subarachnoid vessels, whereas the BBB of the intracerebral vessels and perivascular glia limitans were very resistant to leukaemic cell invasion. This underlines the difference between the subarachnoid and perivascular v. intraparenchymal compartments. Preceding BBB damage may predispose to brain metastases. The parenchymal dissemination of malignant cells was similar to that in primary CNS lymphoma and it followed the same spreading pathways as the extracellular fluid.
Increased production of ubiquitin mRNA in motor neurons after axotomy
Authors: Savedia S. , Kiernan J. A.
Published: May 2008

Ubiquitin targets proteins for attack by certain proteolytic enzymes, but the ubiquitinated cytoplasmic inclusions seen in some chronic neurodegenerative diseases may indicate the occurrence of reparative rather than destructive metabolic events. We have examined the production of ubiquitin in motor neurons of the rat's left hypoglossal nucleus after transection of their axons in circumstances that favour or prevent axonal regeneration. One week after axotomy, in situ hybridization with a radiolabeled cRNA probe revealed a twofold increase in the ubiquitin mRNA content of neurons with regenerating axons (nerve crushed) but no significant change when axonal regeneration had been prevented (nerve transected and ligated). After 2 weeks, ubiquitin mRNA was elevated to about 1.5 times the contralateral control level, regardless of the type of nerve injury, and by 4 weeks there were no longer any differences between the left and right sides. Despite the increased transcription, axotomy was not followed by any change in the quantity of ubiquitin–immunoreactive material in the nuclei or perikarya of hypoglossal neurons as measured by video image analysis of immunohistochemically stained sections. We suggest that ubiquitin is synthesized in neuronal cell bodies and transported into their axons, and that ubiquitin–mediated proteolysis is a metabolic process involved in the elongation of regenerating axons.
Is Purkinje cell loss in Leigh's disease an excitotoxic event secondary to damage to inferior olivary nuclei?*
Authors: Cavanagh J. B.
Published: May 2008

In a series of 17 cases of Leigh's disease it has been observed that there is a close correlation between damage to the inferior olivary nuclei by vasculo–necrotic change and loss of Purkinje cells in the cerebellar cortex. It is suggested that this association may be explained on the basis of the selective loss of climbing fibres causing increased firing activity of Purkinje cells with consequent excessive entry of calcium ions. In these circumstances control of calcium ion regulation in the presence of reduced energy production, which is the basis of this metabolic disease, would be expected to put these cells' survival seriously at risk.
Unusual ubiquitin–positive glial cells in the globus pa 11 id us of normal elderly human brains
Authors: Abe H. , Mehraein P. , Weis S.
Published: May 2008

Unusual glial cells, inconspicuous in routine histological sections, were demonstrated in the globus pallidus using immunohistochemistry for anti–ubiquitin and a modified NOR–silver impregnation technique. These cells were identified as astrocytes and showed the following unusual features: (i) presence of intracytoplasmic vacuoles; (ii) immunoreactivity for ubiquitin; (iii) positive staining with a modified NOR–silver impregnation technique; and (iv) topographical location restricted to the globus pallidus. Quantitative analyses showed the numerical density of these cells to be significantly increased with normal ageing, whereas the presence of the cells was not related to pathological ageing or any other disease process. The data suggest that, not only in neurons but also in glial cells, accumulations of altered proteins can be found, which is probably due to a decline in the proteolytic activity of the cell.
Analysis of the molecular basis of neuropathogenesis of RNA viruses in experimental animals: relevance for human disease?
Authors: Atkins G. J. , Balluz I. M. , Glasgow G. M. , Mabruk M. J. E. M. F. , Natale V. A. I. , Smyth J. M. B. , Sheahan B. J.
Published: May 2008

RNA viruses with segmented genomes were the first model used for molecular analysis of viral neuropathogenesis, since they could be analysed genetically by reassortment. Four viruses with non–segmented genomes have been used as models of neurovirulence and demyelinating disease: JHM coronavirus, Theiler's virus, Sindbis virus and Semliki Forest virus (SFV). Virus gene expression in the central nervous system of infected animals has been measured by in situ hybridization and immunocytochemistry. Cell tropism has been analysed by neural cell culture. Infectious clones have been constructed for Theiler's virus, Sindbis virus and SFV, and these allow analysis of the sequences involved in the determination of neuropathogenesis, through the construction of chimeric viruses and site–specific mutagenesis. Measles and rubella viruses have been studied in animal systems because of their importance for human disease. The importance of two recently discovered mechanisms of neuropathogenesis, antibody–induced modulation of virus multiplication, and persistence of virus in the absence of multiplication, remains to be assessed.
Low density lipoprotein uptake by macrophages in multiple sclerosis plaques: implications for pathogenesis
Authors: Newcombe J. , Li H. , Cuzner M. L.
Published: May 2008

Low density lipoprotein (LDL), the major carrier of plasma cholesterol, may enter the parenchyma of early multiple sclerosis (MS) lesions as a result of blood‐brain barrier damage. We have used antibodies against LDL and epitopes found in LDL oxidized by two peroxidative end‐products, malondialdehyde (MDA) and 4‐hydroxynonenal (4‐HNE), to immunocytochemically stain MS plaques at different stages of pathology. Native LDL, epitopes of MDA‐LDL, peptides of myelin basic protein and neutral lipid oil red O (ORO) staining were found to be co‐localized within foamy macrophages in early and actively demyelinating MS plaques. Thus cho lesterol esters, which are seen as Maltese crosses under polarized light in a proportion of foamy macrophages, appear to be derived from both LDL and myelin. ORO‐negative astrocytes were strongly stained with the antibodies against 4‐HNE‐LDL and MDA‐LDL, suggesting uptake of oxidatively modified protein products alone. Our findings suggest that a large proportion of the plasma LDL which enters the parenchyma of MS plaques is oxidatively modified in the lesion. Lipid peroxidation and oxidized LDL uptake by activated microglia and infiltrating macrophages in the early stages of MS plaque development may play important roles in demyelination.
Hereditary spastic paraparesis with dementia, amyotrophy and peripheral neuropathy. A neuropathological study
Authors: Ferrer I. , Olive M. , Rivera R. , Pou A. , Narberhaust B. , Ugartet A.
Published: May 2008

Hereditary, probably autosomal recessive, spastic paraparesis in two siblings was associated with dementia of frontal lobe type, amyotrophy and peripheral sensory and motor polyneuropathy. Neuropathological findings correlate with neurological deficits, although neuron loss in the caudate and putamen, substantia nigra, and loss of Purkinje cells were clinically silent. Loss of neurons occurred in all cortical layers of the prefrontal lobe and superior temporal gyrus. Immunohistochemical studies showed reduced parvalbumin immunoreactivity in dendrites, and reduced numbers of calbindin D28k‐immunoreactive cells, thus suggesting involvement of cortical local‐circuit neurons. Myelin loss, ubiquitin‐immunoreactive granular deposits, and nerve fibre degeneration in the white matter of the frontal lobes and corpus callosum were also observed. Cerebral and sub‐cortical white matter abnormalities, together with atrophy of the thalamic dorsomedial complex and anterior nucleus, may have accounted for the development of severe dementia in this patient.
Brain stem nuclei in sudden infant death syndrome (SIDS): volumes, neuronal numbers and positions
Authors: Lamont P. , Murray N. , Halliday G. , Hilton J. , Pamphlett R.
Published: May 2008

It has been suggested that the defect underlying the sudden infant death syndrome (SIDS) lies in brain stem nuclei involved in cardiac and respiratory function. However, most studies have not used rigorous quantitative techniques to assess brain stem nuclear volumes and neuronal numbers. We have measured the volume, neuronal numbers and position of brain stem nuclei in 11 SIDS and 11 aged‐matched control infants. Using serial sagittal sections, nuclei involved in maintaining airway patency (hypoglossal, ambiguus and retro‐ambiguus), heart rate (dorsal vagal) and generation of respiratory rhythm (ambiguus and dorsal vagal) were studied. No significant differences were found in nuclear volume increase with age, total neuronal number or nuclear position between SIDS and control cases. These findings support the hypothesis that the nervous system in SIDS may be normal until the final event that kills these infants.
Distribution of tangles and threads in the cerebral cortex in progressive supranuclear palsy
Authors: Hanihara T. , Amano N. , Takahashi T. , Nagatorno H. , Yagashita S.
Published: May 2008

Recent studies have described silver‐ and tau‐positive glia and threads in the degenerating lesions of progressive supranuclear palsy. In this study, Gallyas‐Braak silver impregnation and several immunohistochemical techniques were employed to examine the distribution of tangles, abnormal glia and threads in the cerebral cortex of nine cases of progressive supranuclear palsy. In addition to neurofibrillary tangles, argentophilic glia and threads were impregnated exclusively by GaIIyas‐Braak technique. This technique demonstrated two types of glia profiles: tightly coiled intra‐cytoplasmic profiles surrounding nuclei (coiled profiles) and thorn‐like profiles with radial ramifications (thorn‐like profiles). Thorn‐like profiles are possibly in astrocytes and were detected in the cerebral cortex, while coiled profiles are possibly in oligodendroglia and were detected both in the cerebral cortex and subcortical white matter. Topographically, many neurofibrillary tangles were constantly seen in the frontal cortex and in the pre‐central gyrus. Numerous neurofibrillary tangles were detected in the entorhinal cortex of the two brains. Argentophilic glia and threads were also frequent both in the frontal cortex and the precentral gyrus: however, they were more frequent in the pre‐central gyrus that in the frontal cortex in four of the eight cases examined. In two brains, argentophilic threads were distributed widely in the cerebral cortex and white matter except for the temporal cortex. In immunohistochemical studies, argentophilic glia and threads were mostly positive for Tau 2, and a small number of them were weakly positive for ubiquitin and paired helical filament protein. The immunoproperties of these abnormal glia and threads seemed to be virtually identical to those of neurofibrillary tangles. These findings indicate that cytoskeletal abnormalities related with abnormal tau proteins may occur concordantly both in neuronal and glial cells, especially in the pre‐central gyrus. Cytoskeletal abnormalities occurring in the sub‐cortical nuclei may be involved in the primary motor cortex.
Ultrastructural abnormalities with inclusions in Onuf's nucleus in motor neuron disease (amyotrophic lateral scIerosis)
Authors: Pullen A. H. , Martin J. E.
Published: May 2008

This study describes an ultrastructural examination focused on motor neurons in Onuf's nucleus in the spinal cord of four control patients without neurological disease (45–70 years) and six motor neuron disease (MND) patients (38–79 years; duration 8 months‐19 years) who showed no somato‐vesical dysfunction. Prompted by recent studies suggesting some sphincteric motor neurons may succumb to MND, this study sought to determine whether the wider population of neurons in Onuf's nucleus display ultrastructural cytopathology which is normally undetectable in histological preparations. Spinal cords were removed 3–20 h after death, and 1 mm slices of cord rapidly fixed in modified Karnovsky medium were processed for both light‐ and electronmicroscopy. ‘Control motor neurons’ had intact neuronal and nuclear membranes. Nissl bodies chiefly comprised ordered structures of alternate lamellae of rough endoplasmic reticulum and arrays of polyribo‐somes. The Golgi complexes consisted of multilamellated curvilinear stacks of ER. No intraneuronal filamentous or Bunina body inclusions were observed, but occasional axonal spheroids were seen in the neuropil. In MND. histological evidence of sparing in Onuf's nucleus was associated with abnormal ultrastructure of the motor neurons. Some sphincteric neurons were atrophic, whereas in the others, Nissl bodies were reduced in number, showed loss of structural organization or comprised polyribosomal aggregates. Golgi complexes had disrupted lamellated organization or consisted solely of distended ER. Intraneuronal filamentous Lewy‐body or skein‐like inclusions and Bunina bodies were identified in Onuf's nucleus of three subjects (duration of MND 8 months‐2 years). The results of the present study indicate that Onuf's nucleus is vulnerable in MND, and preservation of sphincter function with qualitative histological evidence of ‘sparing’ does not necessarily imply a corresponding lack of ultrastructural cytopathology in this nucleus.
Apoptosis in cerebral astrocytic tumours and its relationship to expression of the bcl‐2 and p53 proteins
Authors: Ellison D. W. , Steart P. V. , Gatter K. C. , Weller R. O.
Published: May 2008

Apoptosis is an important determinant of tumour growth which can be regulated by the bcl‐2 and p53 genes. This study examines the relationship between apoptosis, growth fraction (Ki‐67 immunolabelling index), and accumulation of the bcl‐2 and p53 proteins in a spectrum of cerebral astrocytic tumours (n=81). including fibrillary astrocytomas (n=16), anaplastic astrocytomas (n=19), and glioblastomas (n=46). Median apoptosis indices (AIs) increased across this spectrum of tumours, and a significant (P<0.0001) correlation was demonstrated between A1 and Ki‐67 labelling index (LI). Immunolabelling with the bcl‐2 antibody was found in 44% of fibrillary astrocytomas, 42% of anaplastic astrocytomas, and 28% of glioblastomas. It was also found in the vascular endothelial proliferation typically seen in glioblastomas, and in the giant, multinucleated cells of some glioblastomas. No clear relationship between AI and bcl‐2 accumulation was evident. Immunolabelling with the p53 antibody was found in 56% of fibrillary astrocytomas, 79% of anaplastic astrocytomas, and 50% of glioblastomas. No clear relationship between AI and patterns of p53 immunolabelling was evident. Equal proportions of p53‐positive tumours were bcl‐2 positive and bcl‐2 negative, but a small proportion of p53‐negative tumours was bcl‐2 positive. The correlation between A1 and Ki‐67 LI is in line with findings in other malignant tumours. We suggest that the regulation of apoptosis in astrocytic tumours is too complex for a clear association between A1 and bcl‐2 and p53 protein expression to be demonstrated.
Expression and distribution of GAP‐43 in human astrocytes in culture
Authors: Moretto G. , Xu R. Y. , Monacot S. , Rizzuto N. , Kim S. U.
Published: May 2008

Expression and distribution of GAP‐43 in human astrocytes in culture By combining mRNA analysis and immunocytochemistry, we investigated the expression of the growth associated protein 43 (GAP‐43) in enriched populations of astrocytes, obtained from mixed cultures of human fetal brains. Total cellular RNA was extracted from cell pellets and reverse transcribed into cDNA; cDNA was subjected to PCR amplification using primers specific for GAP‐43 and PCR products were separated through polyacrylamide gels. Double immunofluorescence staining was performed on dissociated cell cultures using antibodies to glial fibrillary acidic protein (GFAP) and to GAP‐43. Results showed that both transcription and translation for GAP‐43 occur in cultured astrocytes. GAP‐43 immunoreacting material was detected in the cell processes and diffusely in the cytoplasm of GFAP‐positive astrocytes, during early stages of maintenance in vitro. In older cultures, GAP‐43 immunoreactivity persisted in a large percentage of cells, with a tendency to accumulate in perinuclear areas. These observations provide evidence that GAP‐43 is not restricted to neuronal cells. The close spatial association with cyto‐skeletal constituents, as observed in astrocytes. suggests a role for this protein in the control of cell shape, motility and adhesion processes.
Pathology of subcortical visual centres in relation to cortical degeneration in Alzheimer's disease
Authors: Leuba G. , Saini K.
Published: May 2008

Subcortical visual centres such as the lateral geniculate nucleus, the lateral inferior pulvinar and the superior colliculus, together with the primary visual cortex and its adjacent white matter, were studied in 12 Alzheimer brains and five age‐matched controls. The periodic acid methenamine technique was used for the demonstration of senile plaques and the Gallyas technique for neuro‐fibrillary tangles and neuritic threads in the neuropil. In the lateral geniculate nucleus and inferior pulvinar, the presence of periodic acid methenamine‐positive senile plaques was observed in variable numbers in all Alzheimer cases. In the lateral geniculate nucleus, senile plaques were encountered more often in parvocellular than in magnocellular layers, in the interlaminar zones, in the optic radiation and in the adjacent pre‐geniculate nucleus. Gallyas staining did not reveal any neuro‐fibrillary tangles. neuritic threads or neuritic plaques, meaning that in this thalamic region there are mainly amyloid deposits without neuritic degeneration. In the superior colliculus both amyloid and neuritic plaques, as well as neurofibrillary tangles and neuritic threads were encountered in the superficial and deep layers. In the primary visual cortex, all types of senile plaques were observed as well as a rather high number of neurofibrillary lesions in pyramidal neurons, mainly in layers 5 and 6, but also in several types of non‐pyramidal neurons. In the underlying white matter there was a morphologically heterogeneous population of neurofibrillary tangle‐bearing neurons and a considerable number of threads representing degenerating axons, suggesting that degeneration could follow cortico‐subcortical connections. These data demonstrate that lesions in the primary visual structures and pathways are more prevalent than previously observed and could partly explain the visual disturbances in Alzheimer's disease.
Reactive microgIia in Creutzfeldt‐Jakob disease
Authors: Muhleisen H. , Gehrmann J. , Meyermann R.
Published: May 2008

Creutzfeldt‐Jakob disease (CJD) is characterized by a loss of neurons accoinpanied by astrogliosis and spongiform changes in the neuropil. It has been recognized that reactive inicroglia occur in CJD but little is known about the regional distribution and extent of the microglial activation. We have. therefore, examined six brains from cases of sporadic CJD by immunohistochemical labelling of grey and white matter microglia froin frontal, parietal. temporal. and occipital lobes, striatum, thalamus, cerebellum and brain stem with RCA‐I, LCA. CD68. HIA‐DR. and HAM56. Microglial activation occurred in the grey matter where astrogliosis and prion protein (PrP) deposits were prominent. Processes of activated microglia surrounded the outer rim of spongy vacuoles. A diffuse microglial response was seen in the white matter that was immunophenotypically different from grey matter. Double‐labelling with microglial marlters and anti‐PrP showed that activated inicroglia did not contain PrP‐immunoreactivity. Therefore a primary role of microglia in PrP processing seem unlikely. Activated inicroglia may contribute to neuronal damage in CJD due to their cytotoxic potential.
Activation of nuclear factor kB in brains from children with HIV‐I encephalitis
Authors: Dollard S. C. , James H. J. , Sharer L. R. , Epsteint L. G. , Gelbardt H. A. , Dewhurst S.
Published: May 2008

Human immunodeficiency virus type 1 (HIV‐1) infection of the central nervous system is associated with decreased neuronal density in discrete areas of the brain. Neuronal loss may occur via apoptosis, initiated by soluble neurotoxic factors secreted from HIV‐1 infected macrophages and microglia. To examine furlher the molecular events involved in HIV‐1 neuropathogenesis. we assessed the activity of NFkB. an inducible transcription factor involved in the activation of multiple pro‐inflammatory, and potentially neurotoxic, genes. NFkB was analysed by immunocytochemistry using specific antisera to the NFkB p. 50 and p. (75 subunits. Brains from children with HIV‐1 encephalitis and progressive encephalopathy were found to contain increased numbers of NFkB immunoreactive cells, relative to control brains (HIV‐I negative, or HIV‐1 positive nithout encephalitis). Double‐labelling studies using antibodies to CD68, or RCA‐1 lectin, markers for cells of monocyte/ macrophage lineage, revealed an increase in the number of microglia and macrophages with nuclear itnmuno‐reactivity Ior NFkB in association with HIV‐1 encephalitis. NFkB positive multinucleated giant cells were also detected, as were cells which contained both NFkB and HIV‐I antigen. In contrast, the number of neurons and GFAP‐positive astrocytes that were immunoreactive for NFkB was approximately the same in all groups of subjects. These data are consistent with the hypothesis that persistent, high‐level activation of NEkB may promote the sustained production of neurotoxins by microglia and macrophages during HIV‐1 encephalitis.
Evidence for neuronal apoptosis in pontosubicular neuron necrosis
Authors: Brück Y. , Brück W. , Kretzschmar H. A. , Lassmann H.
Published: May 2008

Pontosubicular neuron necrosis (PSN) is characterized by acute neuronal death in the subiculum and the pons occurring in a circumscribed perinatal period. The morphological changes in PSN are quite similar to those described during apoptosis, a form of programmed cell death. Morphological re‐evaluation of the lesions by light and electron microscopy revealed the typical changes of apoptosis with condensed basophilic nuclei and the formation of apoptotic bodies. By analysing DNA fragmentation in situ with a recently established technique, we were able to show that neuronal death in PSN is apoptotic. The demonstration of DNA fragmentation by the in situ tailing technique was reliable in the human autopsy material used in this study and was only slightly affected by autolysis or formalin fixation. The subiculum and the pons are shown to be susceptible to apoptosis at different times during development. PSN thus provides a model in which the process of nerve cell apoptosis in the developing human central nervous system can be studied.
Ultrastructural localization of adhalin, α‐dystroglycan and merosin in normal and dystrophic muscle
Authors: Cullen M. J. , Walsh J. , Roberds S. L. , Campbell K. P.
Published: May 2008

Adhalin and α‐dystroglycan are two components of a complex of proteins that, in conjunction with dystrophin, provide a link between the subsarcolemmal cytoskeleton and the basal lamina of the extracellular matrix of skeletal muscle. In the absence of dystrophin, in Duchenne muscular dystrophy (DMD) and the mdx mouse, levels of adhalin, α‐dystroglycan and other components of the complex, are severely reduced, and it has been speculated that this might be an important factor in precipitating myofibre necrosis. However, there is, as yet, little information on how these proteins interact structurally or functionally. From biochemical data it might be predicted that adhalin and α‐dystroglycan are positioned more peripherally in the muscle cell than dystrophin and more proximal than merosin. Using single and double immunogold labelling we here show that adhalin is localized to the plasma membrane with the majority of the gold probe particles situated on the membrane's outer face, while α‐dystroglycan labelling is seen on material which projects from the outer face and which, in places, forms strands that stretch to the basal lamina. When double labelling of laminin and α‐dystroglycan is carried out, laminin is localized to the proximal face of the basal lamina, facing the α‐dystroglycan. In DMD the labelling of adhalin and α‐dystroglycan is severely reduced quantitatively (although the vestige that remains is positioned normally) but merosin is expressed normally, showing that its incorporation is independent of that of dystrophin and its associated proteins.
Aberrant Timm‐stained fibres in the dentate gyrus following tetanus toxin‐induced seizures in the rate
Authors: Mitchell J. , Gatherer M. , Sundstrom L. E.
Published: May 2008

The present study addresses whether seizures, which result from the chronic block of inhibition caused by an intrahippocampal injection of tetanus toxin, induce axonal sprouting of the hippocampal mossy fibres. Timmstain was used to identify the mossy fibre terminals. in nin of 15 animals killed at 1 month or later after an injection of tetanus toxin. Timm‐stained terminals were observed bilaterally in the inner molecular layer and in seven animals a meshwork of Tim‐stained fibres/terminals was also abserved bilaterally in the outer molecular layer of the fascia dentata. None of these changes were observed in any of the 12 saline‐injected controls. There was no obvious correlation between the number of motor fits an animal exhibited and the amount of Timma‐stained fibre sprouting present in either the inner or outer molecular layer. The Timm‐satined exonal sprouting into the outer molecular layer of the fascia dentata may simply reflect the reinnervation of sites on the granule cell dendrites. previously occupied by the terminals of the hilar somatostatin‐containing cells. These hilar somatostatin‐containing cells which are believed to project to the outer molecular layer are known to succumb to the seizure activity in this animal model of epilepsy.
Apolipoprotein E distribution among different plaque types in Alzheimer's disease: implications for its role in plaque progression
Authors: Sheng J. G. , Mrak‡ R. E. , Griffin W. S. T.
Published: May 2008

We sought to determine the pattern of ApoE immunoreactivity in mesial temporal lobe tissue from 12 Alzheimer patients, age 66–88, and to determine the distribution of this immunoreactivity among different plaque types representing hypothesized stages of plaque evolution. In these patients, the cortical area of ApoE immunoreactivity was 30% that of β‐amyloid. Only 6% of diffuse non‐neuritic amyloid deposits were even weakly ApoE immunoreactive (ApoE+). This is in contrast to our previous demonstration that microglia overexpressing interleukin‐1 (IL‐1) are present in most diffuse non‐neuritic deposits. Eighty‐three per cent of diffuse neuritic plaques and 86% of dense‐core neuritic plaques were highly ApoE+, consistent with IL‐1–induced astrocyte activation and synthesis of ApoE, resulting in the appearance of ApoE immunoreactivity in neuritic plaques. Dense‐core non‐neuritic (‘burned out’) plaques were only rarely (6%) ApoE+. These results, together with the known trophic and toxic effects of ApoE on neurites, suggest that plaque‐associated ApoE contributes to the formation of overgrown degenerating (dystrophic) neurites in plaques. However, the fact that some neuritic plaques are not ApoE+ suggests contributions by additional trophic and toxic factors. Our results are also consistent with a role for ApoE in the condensation of diffuse amyloid deposits into a β‐pleated‐sheet form that occurs concomitant with dystrophic neurite formation in the neuritic β‐amyloid plaques of Alzheimer's disease.
Age‐related changes in the olfactory system of dogs
Authors: Hirai T. , Kojima S. , Shimada A. , Umemura T. , Sakai M. , Itakurat C.
Published: May 2008

Age‐related changes in the olfactory system were examined in 22 dogs ranging in age from 10 to 19 years old. Atrophic changes with degeneration were observed in the olfactory epithelium of dogs older than 14 years; the changes were prominent in the dogs over the age of 17 years. Immunohistochemistry using an anti‐carnosine antibody, which is a marker for the olfactory cells, demonstrated a decrease in the number of olfactory cells. Electron microscopy also showed a decrease in the number of cilia of olfactory cells and microvilli of supporting cells. Atrophic changes with the features of regeneration were rarely observed in the aged animals. Lipofuscin‐like granules in the olfactory epithelium became prominent with age. These age‐related changes were similar to those reported in the olfactory epithelium of man and rats. Dystrophic neurites were not detected by a modified Bielschowsky stain or by neurofilament, synaptophysin and tau immunohistochemistry in the olfactory mucosa. There was no β‐amyloid‐ and ubiquitin‐immunostaining in the olfactory mucosa. Senile brain changes, including cerebrovascular amyloidosis, age‐related astrocytic gliosis and ubiquitin deposits were found in the olfactory bulb, although neurofibrillary tangles and senile plaques were not detected either by a modified Bielschowsky stain or by β‐amyloid immunohistochemistry. These results indicate that dog may be a useful animal model to study the age‐related changes in the olfactory system in man.
Non‐HTLV‐I associated pleomorphic T‐cell lymphoma of the brain mimicking post‐vaccinal acute inflammatory demyelination
Authors: Wanschitz J. , Hainfellner J.‐A. , Simonitsch I. , Schnizer M. , Deisenhammer E. , Terunuma H. , Iwasaki Y. , Budka H.
Published: May 2008

Two weeks after vaccination against tick‐borne encephalitis (TBE), a 57‐year‐old female suddenly developed mental confusion and hemiparesis of the left side. Cranial MRI demonstrated extensive bilateral lesions in the fronto‐parietal white matter of both hemispheres, suggesting an acute inflammatory demyelinating disease following vaccination. Despite administration of high‐dose corticosteroids, the patient died 3 weeks after onset of neurological symptoms. Autopsy revealed diffuse infiltrates of a primary cerebral pleomorphic T‐cell lymphoma of medium and large cell type. PCR on brain tissue for HTLV‐I and serology for anti‐HTLV‐I antibodies in CSF and serum were negative; immunocytochemistry on brain tissue did not detect EBV‐related antigen. This is the first recorded observation of a diffusely infiltrating primary central nervous system T‐cell lymphoma, clinically and radiologically mimicking a fatal acute inflammatory demyelinating complication after vaccination.
The effects of the growth factor‐antagonist, trapidil, on remyelination in the CNS
Authors: McKay J. S. , Blakemore W. F. , Franklin R. J. M.
Published: May 2008

In this study we describe the effects of trapidil, a putative platelet‐derived growth factor‐antagonist, on spontaneously occurring remyelination in rat spinal cord. Demyelination was created in the dorsal funiculus of 6‐ and 11‐week‐old female rats by the direct injection of 1.0 μl of 1% lysolecithin. The animals received daily intra‐peritoneal injections of either trapidil or saline for 21 days, commencing on the day of lesion induction. The 11‐week‐old rats receiving trapidil (60 mg/kg) showed a significant decrease in the extent of oligodendrocyte remyelination. Moreover, those axons that were remyelinated by oligodendrocytes tended to have thinner myelin sheaths than axons remyelinated by oligodendrocytes in the control group. In the 6‐week‐old group, the dose of trapidil which inhibited oligodendrocyte remyelination in the 11‐week‐old animals had a minimal effect on the extent of oligodendrocyte remyelination and no effect on the quality of myelin sheath formation. A higher dose of trapidil (80 mg/kg) was required before significant impairment of oligodendrocyte remyelination was achieved in the younger age group, implying an age‐dependent effect of growth factor‐inhibition of CNS remyelination. These results indicate an important role for growth factors, and in particular PDGF, in the orchestration of oligodendrocyte remyelination in the rodent CNS.
Nerve growth factor production and expression of p75 by Schwann cells and neurofibroblasts in response to M. leprae infection and macrophage secretory products
Authors: Singh N. , Birdi T. J. , Antia N. H.
Published: May 2008

This study describes the changes occurring in vitro in nerve growth factor (NGF) production and expression of p75 by murine Schwann cells and neurofibroblasts, following infection with Mycobacterium leprae and in the presence of macrophage secretory products, using a semiquantitative ELISA. These parameters are compared in two strains of mice, Swiss White (SW) and C57B1/6, as they differ in their response to M. leprae infection; C57B1/6 is the ‘resistant’ strain. On infection, NGF levels remained unaltered in Schwann cells from both strains, while fibroblasts from C57B1/6 strain showed an increase in NGF production. Expression of p75 by Schwann cells was decreased on infection in both strains of mice. In vivo, this opposing effect of infection on NGF production and p75 expression by Schwann cells and neurofibroblasts may result in suboptimal amounts of NGF reaching neurons of the affected leprous nerves. Macrophage secretory products suppressed the production of NGF by infected neurofibroblasts from SW strain mice and the expression of p75 in Schwann cells from both strains. These results indicate that macrophages do not assist in nerve repair in leprosy and the differences in response to macrophage secretory products in the two strains suggest that different mechanisms of nerve repair operate in SW and C57B1/6 mice and presumably in lepromatous and tuberculoid patients.
Astrocytic adhesion molecules are increased in HIV‐1‐associated cognitive/motor complex
Authors: Seilhean D. , Dzia‐Lepfoundzou A. , Sazdovitch V. , Cannella B. , Raine C. S. , Katlama C. , Bricaire F. , Duyckaerts C. , Hauw J.‐J.
Published: May 2008

Half of AIDS dementia cases are associated with HIV‐encephalitis or myelin pallor. Another half die with no HIV‐related neuropathological changes. Previous observations suggest that cerebral dysfunction may result from more subtle cellular interactions, and that some of them may be mediated by cell adhesion molecules. In the present study the expression by astrocytes and endothelial cells of intercellular adhesion molecule‐1 (ICAM‐1), and vascular cell adhesion molecule‐1 (VCAM‐1) was analysed as a function of the neuropathological diagnosis, the density of astrogliosis and of HIV‐1 positive cells, and of the mental status. Twelve AIDS cases, without focal brain lesion, eight of whom were demented, were selected from a prospective study. They were compared with six control cases with multiple sclerosis, and with six control patients without neurological disease. ICAM‐1 and VCAM‐1 expression was localized by immunofluorescence and confocal microscopy. HIV protein gp41 was detected by immunohistochemistry on adjacent sections. Endothelial expression of ICAM‐1 and VCAM‐1 was significantly up‐regulated in all AIDS patients. VCAM‐1 only was related to myelin pallor. The density of VCAM‐1 or ICAM‐1 positive astrocytes increased in demented AIDS patients, independently of the neuropathological findings or the density of gp41 positive cells. Expression of cell adhesion molecules, together with other secondary mechanisms such as secretion of cytokines may play a role in the pathogenesis of white matter lesions leading to HIV‐1‐associated cognitive changes.
In vivo toxicity of prion protein in murine scrapie: ultrastructural and immunogold studies
Authors: Jeffrey M. , Goodsir C. M. , Bruce M. E. , McBride P. A. , Fraser J. R.
Published: May 2008

Prion protein (PrP) is a cell surface, host coded, sialoglycoprotein which accumulates in excess in scrapie, Creutzfeldt‐Jakob disease, bovine spongiform encephalopathy and other transmissible spongiform encephalopathies. Infection of mice with the 87 V or ME7 scrapie strains results in distinctive and very different light microscopical patterns of vacuolation and disease specific PrP accumulation. In both of these scrapie strains immunogold electron microscopy was used to locate PrP to the plasmalemma of neurons from where it was released into the neuropil. Initial PrP accumulation around neurons and in early plaques lacking amyloid fibrils was generally not associated with morphological changes either of the neuron or dendrite releasing the PrP or in the adjacent neuropil in which excess PrP accumulated. However, accumulation of pre‐amyloid PrP in some brain areas was associated with specific degeneration of dendritic spines and axon terminals. Initial PrP aggregation into fibrils was also associated with tissue damage with both ME7 and 87 V plaques and diffuse accumulations. Tissue damage associated with fibrillogenesis was localized and would not be expected to have clinical significance. We conclude that pre‐amyloid PrP release and accumulation is not invariably toxic, either to the neuron releasing PrP or to the neuropil into which it is released. However, axon terminal degeneration and dendritic spine loss in some neuroanatomical areas may be indicative of specific PrP toxicity and may be the main cause of neurological dysfunction in murine scrapie.
DNA‐fragmentation and expression of apoptosis‐related proteins in experimentally denervated and reinnervated rat facial muscle
Authors: Tews D. S. , Goebel H. H. , Schneider I. , Gunkel A. , Stennert E. , Neiss W. F.
Published: May 2008

Muscle fibres may undergo apoptotic cell death in several neuromuscular disorders such as denervated muscle fibres in spinal muscular atrophies. We investigated DNA‐fragmentation (in situ by the TUNEL‐method) and expression of apoptosis‐associated proteins in experimentally denervated and reinnervated rat facial muscle up to 24 weeks after surgery to evaluate the rate and time lapse of apoptotic muscle fibre loss. While denervated muscle displayed constantly high rates of DNA‐fragmentation, denervated and immediately reinnervated muscle showed a distinct decrease of primarily elevated DNA‐cleavage, finally resembling rates of normal controls. Denervated muscle fibres revealed strong immunoreactivity of the anti‐apoptotic proteins bcl‐2 and bcl‐xL, and the pro‐apoptotic factor bax. In reinnervated muscle fibres, only bcl‐2 was constantly up‐regulated while bcl‐xL and bax diminished after the 7th week. The present findings indicate that denervation may prompt muscle fibres to activate an intrinsic ‘suicide’ programme to undergo apoptosis. High levels of bcl‐2 after denervation may sustain cell survival until reinnervation, e.g. after accidental nerve damage or in neurodegenerative disorders. Furthermore, increasing levels of bcl‐2 are able to neutralize high apoptosis‐promoting bax levels. Interventions modifying DNA‐fragmentation and the expression of apoptosis‐related proteins may lead to new therapeutic concepts in denervating disorders of muscle in the absence of other primary therapies.
Apoptosis in measles virus‐infected human central nervous system tissues
Authors: McQuaid S. , McMahon J. , Herron B. , Cosby S. L.
Published: May 2008

The extent of apoptotic cell death was examined in central nervous system (CNS) tissues from three cases of subacute sclerosing panencephalitis (SSPE). Apoptosis was demonstrated by in situ end‐labelling of DNA in formalin‐fixed, paraffin‐embedded tissue sections. Measles virus and cell types were labelled by immunohistochemistry and/or in situ hybridization. Furthermore, bcl‐2 expression in SSPE was examined by immunohistochemistry. All three cases exhibited varying degrees of apoptosis in all CNS areas studied. Brain tissue from a non‐neurological control case did not show any significant apoptosis. Characterization of cell types demonstrated neurons, oligodendrocytes, lymphocytes and microglia undergoing apoptosis. A linear relationship could not be established between virus burden and the extent of apoptosis in any particular area. Virus‐negative cells were observed which were undergoing apoptosis. Bcl‐2 immunoreactivity in SSPE was confined to the infiltrating cell population. These results suggest that apoptosis of various cell types may contribute to the neuropathogenesis of measles virus infection in the human CNS, either as a direct effect of viral infection or by cytokine‐mediated responses.
Long‐term effects of Semliki Forest virus infection in the mouse central nervous system
Authors: Donnelly S. M. , Sheahan B. J. , Atkins G. J.
Published: May 2008

Semliki Forest virus (SFV) infection of mice is used as a model to study pathogenic processes occurring in viral encephalitis and demyelinating disease. In this study, the long‐term effects of infection by the avirulent M9 mutant of SFV on the central nervous system (CNS) of BALB/c and SJL mice were determined. The presence of infectious virus, viral RNA and cytokine mRNA in the brains of individual mice and the presence of lesions in the spinal cords of the same mice up to 360 days post‐infection (d.p.i.) were analysed in order to detect any correlation between these parameters of pathogenesis. Infectious virus could not be detected beyond 7 d.p.i. for either mouse strain. Reverse transcriptase polymerase chain reaction (RT‐PCR) was used to detect the presence of the E2 and nsP1 regions of the virus genome and mRNA for interferon‐γ and tumour necrosis factor‐α. Viral RNA could be detected up to 90 d.p.i. for both mouse strains. Cytokine mRNA could be detected up to 28 d.p.i. for BALB/c mice but up to 360 d.p.i. for SJL mice. Inflammatory lesions, which were associated with cytokine mRNA expression, were not detected in BALB/c mice beyond 28 d.p.i. but were detected in two SJL mice at 90 d.p.i. It is concluded that M9‐SFV infection induces long‐term prolonged expression of pro‐inflammatory cytokines in the CNS of the majority of SJL (but not BALB/c) mice which is not associated with persistence of the virus genome. M9‐SFV infection of SJL mice may be a relevant model for the pathogenesis of multiple sclerosis in man.
Expression of pro‐ and anti‐apoptosis gene products in brains from paediatric patients with HIV‐1 encephalitis
Authors: Krajewski S. , James H. J. , Ross J. , Blumberg B. M. , Epstein L. G. , Gendelman H. E. , Gummuluru S. , Dewhurst S. , Sharer L. R. , Reed J. C. , Gelbard H. A.
Published: May 2008

We have previously demonstrated the presence of DNA fragmentation in neurons, macrophages and microglia consistent with apoptosis, but not in reactive astrocytes in brain tissue from paediatric patients with HIV‐1 encephalitis (HIVE). To further understand the underlying mechanism(s) for these findings as they relate to gene‐directed neural cell death, we studied the in‐situ expression of the Bcl‐2 family of proteins, including the pro‐apoptosis gene product Bax, the anti‐apoptosis gene product Bcl‐2, and Bcl‐x. We demonstrate significantly elevated numbers of Bax‐positive microglia and macrophages immunoreactive in basal ganglia and cerebral cortex of children who had HIVE, in comparison to HIV‐1 infected children without encephalitis or children who were seronegative for HIV‐1. In contrast, patients with HIVE, but not HIV‐1 without encephalitis, or seronegative controls, had increased expression of Bcl‐2 and Bcl‐x in reactive astrocytes in cortex and basal ganglia. In vitro studies using Western blot analysis demonstrated an up‐regulation in the levels of Bax, and phosphorylated (i.e. inactive) Bcl‐2 in HIV‐1 infected macrophages, and in LPS‐activated macrophages, relative to levels in virus‐negative unstimulated macrophages. These results suggest that productive HIV‐1 infection, or cellular activation, renders macrophages more vulnerable to apoptosis. Taken together, these findings suggest that brain‐resident macrophages and microglia in patients with HIV‐1 encephalitis are more prone to undergo apoptosis and that astrocytes in contrast may be resistant to apoptosis. This may represent a mechanism to limit microglial activation and the spread of productive HIV‐1 infection in the CNS of children with HIV‐1 encephalitis.
Region‐selective glutamine synthetase expression in the rat central nervous system following portocaval anastomosis
Authors: Suárez I. , Bodega G. , Arilla E. , Fernández B.
Published: May 2008

Glutamine synthetase (GS) content was investigated using immunohistochemical methods in the hippocampus, cerebellum and spinal cord of rats after long‐term portocaval anastomosis (PCA). Six months after surgery, GS content was increased in several areas of each region and decreased in others, compared with controls. In the hippocampus, the CA1–CA3 pyramidal subfields and the dentate molecular layer had a high level of GS expression; PCA reduced GS content in other hippocampal regions, such as the dentate hilus. In the cerebellum, PCA significantly increased GS immunoreactivity in the Bergmann glial processes of the molecular layer and decreased GS immunoreactivity in astrocytes of the granule cell layer. In the spinal cord, GS immunoreactivity increased in the dorsal horn and decreased in the ventral horn. Blood vessels located in zones with GS‐immunopositive perineuronal astrocytes in PCA‐exposed brains were surrounded by strongly GS‐immunostained perivascular processes. These results suggest that PCA exposure had a differential effect on GS expression in different regions of the central nervous system. The increased immunoreactivity of GS‐positive cells in PCA‐exposed brains correlates with glutamatergic areas, which may contribute to protecting neurons against extracellular glutamate and/or ammonia excess.