Fulminant corticobasal degeneration: a distinct variant with predominant neuronal tau aggregates.

Corticobasal degeneration typically progresses gradually over 5-7 years from onset till death. Fulminant corticobasal degeneration cases with a rapidly progressive course were rarely reported (RP-CBD). This study aimed to investigate their neuropathological characteristics. Of the 124 autopsy-confirmed corticobasal degeneration cases collected from 14 centres, we identified 6 RP-CBD cases (4.8%) who died of advanced disease within 3 years of onset. These RP-CBD cases had different clinical phenotypes including rapid global cognitive decline (N = 2), corticobasal syndrome (N = 2) and Richardson's syndrome (N = 2). We also studied four corticobasal degeneration cases with an average disease duration of 3 years or less, who died of another unrelated illness (Intermediate-CBD). Finally, we selected 12 age-matched corticobasal degeneration cases out of a cohort of 110, who had a typical gradually progressive course and reached advanced clinical stage (End-stage-CBD). Quantitative analysis showed high overall tau burden (p = 0.2) and severe nigral cell loss (p = 0.47) in both the RP-CBD and End-stage-CBD groups consistent with advanced pathological changes, while the Intermediate-CBD group (mean disease duration = 3 years) had milder changes than End-stage-CBD (p < 0.05). These findings indicated that RP-CBD cases had already developed advanced pathological changes as those observed in End-stage-CBD cases (mean disease duration = 6.7 years), but within a significantly shorter duration (2.5 years; p < 0.001). Subgroup analysis was performed to investigate the cellular patterns of tau aggregates in the anterior frontal cortex and caudate by comparing neuronal-to-astrocytic plaque ratios between six RP-CBD cases, four Intermediate-CBD and 12 age-matched End-stage-CBD. Neuronal-to-astrocytic plaque ratios of Intermediate-CBD and End-stage-CBD, but not RP-CBD, positively correlated with disease duration in both the anterior frontal cortex and caudate (p = 0.02). In contrast to the predominance of astrocytic plaques we previously reported in preclinical asymptomatic corticobasal degeneration cases, neuronal tau aggregates predominated in RP-CBD exceeding those in Intermediate-CBD (anterior frontal cortex: p < 0.001, caudate: p = 0.001) and End-stage-CBD (anterior frontal cortex: p = 0.03, caudate: p = 0.01) as demonstrated by its higher neuronal-to-astrocytic plaque ratios in both anterior frontal cortex and caudate. We did not identify any difference in age at onset, any pathogenic tau mutation or concomitant pathologies that could have contributed to the rapid progression of these RP-CBD cases. Mild TDP-43 pathology was observed in three RP-CBD cases. All RP-CBD cases were men. The MAPT H2 haplotype, known to be protective, was identified in one RP-CBD case (17%) and 8 of the matched End-stage-CBD cases (67%). We conclude that RP-CBD is a distinct aggressive variant of corticobasal degeneration with characteristic neuropathological substrates resulting in a fulminant disease process as evident both clinically and pathologically. Biological factors such as genetic modifiers likely play a pivotal role in the RP-CBD variant and should be the subject of future research.

Laminar distribution of the pathological changes in sporadic frontotemporal lobar degeneration with transactive response (TAR) DNA-binding protein of 43 kDa (TDP-43) proteinopathy: a quantitative study using polynomial curve fitting.

AIMS: Previous data suggest heterogeneity in laminar distribution of the pathology in the molecular disorder frontotemporal lobar degeneration (FTLD) with transactive response (TAR) DNA-binding protein of 43 kDa (TDP-43) proteinopathy (FTLD-TDP). To study this heterogeneity, we quantified the changes in density across the cortical laminae of neuronal cytoplasmic inclusions, glial inclusions, neuronal intranuclear inclusions, dystrophic neurites, surviving neurones, abnormally enlarged neurones, and vacuoles in regions of the frontal and temporal lobe. METHODS: Changes in density of histological features across cortical gyri were studied in 10 sporadic cases of FTLD-TDP using quantitative methods and polynomial curve fitting. RESULTS: Our data suggest that laminar neuropathology in sporadic FTLD-TDP is highly variable. Most commonly, neuronal cytoplasmic inclusions, dystrophic neurites and vacuolation were abundant in the upper laminae and glial inclusions, neuronal intranuclear inclusions, abnormally enlarged neurones, and glial cell nuclei in the lower laminae. TDP-43-immunoreactive inclusions affected more of the cortical profile in longer duration cases; their distribution varied with disease subtype, but was unrelated to Braak tangle score. Different TDP-43-immunoreactive inclusions were not spatially correlated. CONCLUSIONS: Laminar distribution of pathological features in 10 sporadic cases of FTLD-TDP is heterogeneous and may be accounted for, in part, by disease subtype and disease duration. In addition, the feedforward and feedback cortico-cortical connections may be compromised in FTLD-TDP.

TorsinB expression in the developing human brain.

Familial, early onset, generalized torsion dystonia is the most common and severe primary dystonia. The majority of cases are caused by a 3-bp deletion (GAG) in the coding region of the DYT1 (TOR1A) gene. The cellular and regional distribution of torsinA protein, which is restricted to neuronal cells and present in all brain regions by the age of 2 months has been described recently in human developing brain. TorsinB is a member of the same family of proteins and is highly homologous with its gene adjacent to that for torsinA on chromosome 9q34. TorsinA and torsinB share several remarkable features suggesting that they may interact in vivo. This study examined the expression of torsinB in the human brain of fetuses, infants and children up to 7 years of age. Our results indicate that torsinB protein expression is temporarily and spatially regulated in a similar fashion as torsinA. Expression of torsinB protein was detectable beginning at four to 8 weeks of age in the cerebellum (Purkinje cells), substantia nigra (dopaminergic neurons), hippocampus and basal ganglia and was predominantly restricted to neuronal cells. In contrast to torsinA, torsinB immunoreactivity was found more readily in the nuclear envelope. High levels of torsinB protein were maintained throughout infancy, childhood and adulthood suggesting that torsinB is also needed for developmental events occurring in the early postnatal phase and is necessary for functional activity throughout life.

HIV leucoencephalopathy and TNFalpha expression in neurones.

BACKGROUND: Human immunodeficiency virus (HIV) leucoencephalopathy (HIVL) is an uncommon and rapidly progressive form of AIDS dementia complex (ADC) that has remained poorly understood. Tumour necrosis factor alpha (TNFalpha), which has been implicated in the pathogenesis of ADC, is predominantly localised in macrophages in the HIV infected brain, although in vitro studies indicate that neurones can express this cytokine. OBJECTIVE: To examine the clinical/neuroradiological features of HIVL and the expression of TNFalpha in HIVL. METHODS: Six patients who presented with rapidly progressive dementia within four to 12 weeks of the primary manifestation of their HIV infection were evaluated. Clinical history, treatment regimens, and imaging studies were reviewed, and brain samples from three of the patients were studied by means of immunohistochemistry. RESULTS: Imaging studies showed diffuse bilateral deep white matter changes in all six patients. Clinical and imaging abnormalities improved in five of the six patients within weeks after initiation of antiretroviral treatment. Brain biopsies of two showed pronounced microglia/macrophage activation, but only scant viral protein (gp41) expression. Staining for TNFalpha was found in microglia/macrophages, and surprisingly, in neurones also. Postmortem analysis of a third patient also showed TNFalpha expression in neurones of the frontal cortex and basal ganglia. CONCLUSION: This study provides the first demonstration of staining for TNFalpha in the neurones of the HIV infected brain, and suggests that the process underlying this rapidly progressive form of ADC may reflect indirect mechanisms mediated by host factors, particularly TNFalpha.

TorsinA expression is detectable in human infants as young as 4 weeks old.

Familial, early onset, generalized torsion dystonia is the most common and severe primary dystonia. The majority of cases are caused by a 3-bp deletion (GAG) in the coding region of the DYT1 (TOR1A) gene. The cellular and regional distribution of torsinA protein and its message has been described previously in several regions of normal adult human and rodent brain. This study examines the expression of torsinA in the developing human brain of fetuses, infants and children up to 7 years of age in four selected brain regions. Expression of torsinA protein was detectable beginning at 4 to 8 weeks of age postnatally in the cerebellum (Purkinje cells), substantia nigra (dopaminergic neurons), hippocampus and basal ganglia. Prominent torsinA immunoreactivity was not seen before 6 weeks of age postnatally, a period associated with synaptic remodeling, process elimination and the beginning of myelination. Our results indicate that torsinA protein expression is temporally and spatially regulated and is present in all brain regions studied by the age of 2 months on into adulthood.

Most cases of dementia with hippocampal sclerosis may represent frontotemporal dementia.

Hippocampal sclerosis dementia (HSD) is a disease of unknown etiology and pathogenesis. To determine whether HSD cases could be reclassified as variants of frontotemporal dementia (FTD), a heterogeneous group of disorders, 18 brain autopsy cases previously diagnosed as HSD were re-evaluated. In 11 cases, ubiquitinated neuronal inclusions, similar to those of motor neuron disease inclusion dementia (MNDID), were found. Brain levels of soluble and insoluble tau were normal. Most patients with pathologic findings of HSD may actually have the MNDID variant of FTD.

Tau protein expression in frontotemporal dementias.

The syndrome of frontotemporal dementia represents a diverse group of diseases presenting with behavioral and cognitive disturbances. The expression of the microtubule-associated protein tau was studied in postmortem samples of frontal cortex of 19 cases (12 Pick's disease A, B, C; 4 dementia lacking distinct histology; 3 motor neuron disease type) by Western blotting with a phosphorylation-independent anti-tau antibody. The presence of tau protein was detected in all cases evaluated, including the 11 brains classified as frontotemporal lobe degeneration (diagnostic categories Pick's disease B, C and dementia lacking distinct histology). These findings indicate that the recently reported decreased expression of tau protein in frontotemporal lobe degeneration represents pathogenic mechanism of neurodegeneration detectable only in a special subset of these disorders.

NFkappaB activation, TNF-alpha expression, and apoptosis in the AIDS-Dementia-Complex.

The role of NFkappaB activation and its relationship to inflammatory mediators and apoptosis in the HIV-infected brain have remained uncertain. The cellular and regional distribution of NFkappaB, TNF-alpha, and apoptosis was examined in the frontal cortex (FC), deep white matter (DWM) and the basal ganglia (BG) of 17 patients with ADC. Nuclear staining for NFkappaB was localized predominantly to perivascular microglia/macrophages in the BG and DWM and correlated with ADC severity. Correlations were further found with HLA-DR, iNOS, TNF-alpha, and gp41 expression in these regions. The number of TUNEL-positive cells, particularly in the BG, correlated with ADC stage. Logistic regression analysis further showed a significant relationship between the likelihood of TUNEL staining in the BG and worsening cognitive impairment.

Human immunodeficiency virus infection, inducible nitric oxide synthase expression, and microglial activation: pathogenetic relationship to the acquired immunodeficiency syndrome dementia complex.

The regional expression of immune-mediated and neurotoxic events in the human immunodeficiency virus (HIV)-infected brain in relationship to the acquired immunodeficiency syndrome (AIDS) dementia complex (ADC) and brain pathology remains uncertain. The extent of gp41, inducible nitric oxide synthase (iNOS), and HLA-DR expression was examined in the frontal lobe and basal ganglia of 25 patients at varying stages of ADC. The expression of gp41 and iNOS was present predominantly in perivascular cells and most often in the basal ganglia. Staining for gp41 correlated significantly with iNOS in the basal ganglia, whereas the severity of staining for gp41 and iNOS in the basal ganglia and white matter was significantly greater in subjects with moderate to severe dementia compared with those with milder impairment. The degree of macrophage staining in the white matter and basal ganglia also correlated significantly with ADC severity and was more abundant than gp41 or iNOS staining, particularly in the white matter. Logistic regression analysis revealed that staining for iNOS and gp41 increased linearly with ADC severity and was significantly more abundant in the basal ganglia compared with the white matter. Double-immunolabeling studies colocalized iNOS predominantly to macrophage/microglia and to gp41-positive cells. The expression of iNOS and gp41 in the basal ganglia combined with immune activation contributes to the development and progression of the clinical syndrome.

Tyrosine hydroxylase-immunoreactive elements in the human globus pallidus and subthalamic nucleus.

In contrast to the well-established dopaminergic innervation of the neostriatum, the existence of dopaminergic innervation of the subthalamic nucleus and globus pallidus is controversial. In the present study, tyrosine hydroxylase (TH)-immunoreactive elements were observed by light microscopy after antigen retrieval in the subthalamic nucleus and in the internal and external segments of the globus pallidus in postmortem human brain. Small islands of apparent neostriatal tissue with abundant arborization of fine, TH-immunoreactive axons in the vicinity of calbindin-positive small neurons resembling neostriatal medium spiny neurons were present in the external segment of the globus pallidus. Large numbers of medium-large, TH-immunoreactive axons were observed passing above and through the subthalamic nucleus and through both pallidal segments; these are presumed to be axons of passage on their way to the neostriatum. In addition, fine, TH-immunoreactive axons with meandering courses, occasional branches, and irregular outlines, morphologically suggestive of terminal axon arborizations with varicosities, were seen in both pallidal segments, including the ventral pallidum, and the subthalamic nucleus, consistent with a catecholaminergic (probably dopaminergic) innervation of these nuclei. This finding suggests that, in Parkinson's disease and in animal models of this disorder, loss of dopaminergic innervation might contribute to abnormal neuronal activation in these three nuclei.

Lost caps in histological counting methods.

BACKGROUND: In methods with the goal of counting objects in a sectioned tissue volume by examining their profiles or segments in the sections, lost caps, i.e., small object fragments unnoticed or missing at the section surfaces, are an unavoidable issue. METHODS AND RESULTS: The problem of lost caps is examined as it applies to four methods for counting in histological sections, the method usually referred to as the Abercrombie correction, the empirical method, the optical disector, and the physical disector. CONCLUSIONS: Lost caps are an insoluble problem in the Abercrombie method; the lost caps error correction factor should be incorporated into the Abercrombie equation. Lost caps cancel out in the optical disector. The empirical method logically requires, to avoid lost caps error, either a preliminary blind identification of object segments in the serial sections or identification of segments with reference to adjacent sections in the counting sections. Similarly, the physical disector method requires either a preliminary blind identification of object segments in both look-up and sampling sections, or use of three sections rather than two.

What was wrong with the Abercrombie and empirical cell counting methods? A review.

When a tissue volume is sectioned, cells or other objects are cut into segments by the sectioning process. The Abercrombie and empirical methods count object segments in histological sections and then apply a correction formula to convert the segment count to object number. There has been considerable recent controversy over whether these methods should be abandoned (in favor of the disector). Although both methods appear unbiased as thought experiments on paper, regardless of variation in object size, shape, or orientation, in practice two problems are inherent in the segment-counting approach: the practical problem of lost caps and a conceptual flaw that becomes apparent only when a need for unbiased estimation of certain factors in the correction formulae is seriously addressed. The Abercrombie method is inevitably biased by lost caps, whereas in the empirical method, this potential bias can be avoided. In the Abercrombie formula, the relevant factor to be estimated (aside from section thickness) is H, mean object height in the axis perpendicular to the section plane, and in the empirical method, it is the ratio of segment number to object number. In both methods, the factor in question should be estimated from an unbiased sample of the total population of objects. But unbiased selection of a statistically adequate number of objects for this estimation constitutes an unbiased, statistically adequate count. Once this is done, there is no reason to complete the steps for estimation of the factor; the count in this specimen is finished. It is shown that the empirical method's serial section procedure can be used to estimate H. This estimate is more sensitive to lost caps than the Abercrombie equation, but, when the formula for H is substituted into the Abercrombie equation, the lost caps error disappears. However, this approach is useless, as making this substitution transforms the Abercrombie equation into the empirical method equation.

Centenary of Gaule and Lewin, pioneers in cell counting methodology.

We commemorate the one hundredth anniversary of the publication of a pioneering paper on cell counting, by Gaule and Lewin. Their paper describes a new method for counting cells in tissue sections. First they found the mean number of cell profiles per cell by examining 50 selected cells in serial sections. Then they counted the total number of cell profiles in the ganglion, and finally divided this total profile number by the mean number of profiles per cell. They thought this method more accurate than counting cells by counting only profiles that showed the nucleolus because they noted that a cell's nucleolus sometimes appeared in more than one section and that a single cell could have more than one nucleolus.

Phenotypic characterization of individuals with 30-40 CAG repeats in the Huntington disease (HD) gene reveals HD cases with 36 repeats and apparently normal elderly individuals with 36-39 repeats.

Abnormal CAG expansions in the IT-15 gene are associated with Huntington disease (HD). In the diagnostic setting it is necessary to define the limits of the CAG size ranges on normal and HD-associated chromosomes. Most large analyses that defined the limits of the normal and pathological size ranges employed PCR assays, which included the CAG repeats and a CCG repeat tract that was thought to be invariant. Many of these experiments found an overlap between the normal and disease size ranges. Subsequent findings that the CCG repeats vary by 8 trinucleotide lengths suggested that the limits of the normal and disease size ranges should be reevaluated with assays that exclude the CCG polymorphism. Since patients with between 30 and 40 repeats are rare, a consortium was assembled to collect such individuals. All 178 samples were reanalyzed in Cambridge by using assays specific for the CAG repeats. We have optimized methods for reliable sizing of CAG repeats and show cases that demonstrate the dangers of using PCR assays that include both the CAG and CCG polymorphisms. Seven HD patients had 36 repeats, which confirms that this allele is associated with disease. Individuals without apparent symptoms or signs of HD were found at 36 repeats (aged 74, 78, 79, and 87 years), 37 repeats (aged 69 years), 38 repeats (aged 69 and 90 years), and 39 repeats (aged 67, 90, and 95 years). The detailed case histories of an exceptional case from this series will be presented: a 95-year-old man with 39 repeats who did not have classical features of HD. The apparently healthy survival into old age of some individuals with 36-39 repeats suggests that the HD mutation may not always be fully penetrant.

Lack of association of the apoE4 allele with hippocampal sclerosis dementia.

We determined the apolipoprotein E4 (apoE) genotype in 12 cases of autopsy-confirmed hippocampal sclerosis dementia (HSD), a disorder characterized pathologically by neuronal degeneration, predominantly of temporal lobe structures, without senile plaques or neurofibrillary tangles. The frequency of the apoE4 allele in HSD was 12.5%, similar to that of a control population and significantly different from the approximately 40% found in Alzheimer's disease (AD) (P < 0.001). These observations suggest that apoE4 is not a risk factor for HSD.

Accuracy of clinical diagnosis of Alzheimer disease and clinical features of patients with non-Alzheimer disease neuropathology.

Neuropathological examination confirmed the clinical diagnosis of possible or probable Alzheimer disease (AD) in 90 of the first 100 patients who came to autopsy at the Johns Hopkins Alzheimer's Disease Research Center. In 10 cases, postmortem brain examination did not confirm AD but revealed variable patterns of neuronal loss in neocortex and limbic structures without amyloid deposits. The most common pattern of degeneration was relatively isolated hippocampal sclerosis (HS). Despite the finding that the 10 patients with non-AD neuropathology were ill for less time and were less cognitively impaired at study entry than those patients with definite AD, they had shorter survival times and showed equal behavioral disturbance at study entry (on a standardized measure). The clinical case reports included here suggest early and progressive prominent behavioral disturbance and other indexes of rapid illness progression in three of the four HS patients and two other non-AD patients. We conclude that the criteria of the National Institute of Neurological Disorders and Stroke/Alzheimer Disease and Related Disorders Association for possible or probable AD are highly accurate and that misdiagnosis is most likely to occur early in the course of illness and in patients with prominent behavioral disturbance or other atypical features.

Neuronal loss from the subthalamic nuclei in a patient with progressive chorea.

We present a case of an 80-year-old man who developed a seizure disorder at age 66 and was treated with chronic phenytoin. In the last 3 years of his life, he developed multiple neurological deficits, including bilateral chorea, ataxic gait, sensory neuropathy, and progressive dementia. After death from pneumonia, autopsy examination of the patient's brain was most remarkable for a selective loss of neurons from both subthalamic nuclei and Purkinje cell loss in the cerebellum. This pattern of injury is consistent with a toxic process and does not fit previously characterized pathological syndromes known to be associated with movement disorders or dementia or both. Phenytoin has been shown to cause choreiform movements, peripheral neuropathy, and cognitive decline in some patients, but the pathological basis for these changes has not been elucidated. The patient's chorea was very likely the result of neuronal loss in the subthalamic nuclei, but causes for his dementia and neuropathy were not found. The pathological findings may represent either an unusual form of chronic phenytoin toxicity or a previously undescribed primary degenerative brain syndrome.

Evidence for apoptotic cell death in Huntington disease and excitotoxic animal models.

Huntington disease (HD) is an inherited neurodegenerative disorder characterized by selective death of striatal medium spiny neurons. Intrastriatal injections of glutamate receptor agonists (excitotoxins) recapitulate some neuropathological features of this disorder. Although this model suggests that excitotoxic injury may be involved in HD, the exact mechanisms of cell death in HD and its models are unknown. The present study was designed to test the hypothesis that HD can develop via the activation of an apoptotic mechanism of cell death and to examine whether excitotoxic striatal lesions with quinolinic acid in rats represent accurate models of HD. To characterize cell death, we employed DNA electrophoresis, electron microscopy (EM), and the terminal transferase-mediated (TdT) deoxyuridine triphosphate (d-UTP)-biotin nick end labeling (TUNEL) method for the in situ detection of DNA strand breaks. In the neostriatum of individuals with HD, patterns of distribution of TUNEL-positive neurons and glia were reminiscent of those seen in apoptotic cell death during normal development of the nervous system; in the same areas, nonrandom DNA fragmentation was detected occasionally. Following excitotoxic injury of the rat striatum, internucleosomal DNA fragmentation (evidence of apoptosis) was seen at early time intervals and random DNA fragmentation (evidence of necrosis) at later time points. In addition, EM detected necrotic profiles of medium spiny neurons in the lesioned rats. In concert, these results suggest that apoptosis occurs in both HD and excitotoxic animal models and that apoptotic and necrotic mechanisms of neuronal death may occur simultaneously within individual dying cells in the excitotoxically injured brain. However, the distribution of dying neurons in the neostriatum, the degree of glial degeneration, and the involvement of striatofugal pathways are very different between HD and excitotoxically damaged striatum. The present study suggests that multiple methods should be employed for a proper characterization of neuronal cell death in vivo.

Comparison of new and traditional methods for detection of senile plaques in Alzheimer's disease.

The pathologic diagnosis of Alzheimer's disease (AD) rests upon the identification of senile plaques and neurofibrillary tangles (NFT) in brain tissue. Methods for staining these structures vary in their sensitivity. Six different silver stains and immunocytochemistry for the beta-amyloid (A beta) peptide were compared for sensitivity in staining of plaques and tangles. For staining of plaques, the silver stains fell into two groups: one group stained primarily large, distorted neurites in classic plaques, and the other stained primarily fine, filamentous elements in diffuse plaques and at the periphery of classic plaques. Our recently developed "quick silver" method demonstrated the highest number of plaques. Sensitivity of NFT staining also varied considerably. The quick silver and Yamamoto-Hirano methods were best for staining both plaques and NFT.