Neuropathology of parkinsonism-dementia complex and amyotrophic lateral sclerosis of Guam: an update

Endemic parkinsonism: clusters, biology and clinical features

The term 'endemic parkinsonism' refers to diseases that manifest with a dominant parkinsonian syndrome, which can be typical or atypical, and are present only in a particular geographically defined location or population. Ten phenotypes of endemic parkinsonism are currently known: three in the Western Pacific region; two in the Asian-Oceanic region; one in the Caribbean islands of Guadeloupe and Martinique; and four in Europe. Some of these disease entities seem to be disappearing over time and therefore are probably triggered by unique environmental factors. By contrast, other types persist because they are exclusively genetically determined. Given the geographical clustering and potential overlap in biological and clinical features of these exceptionally interesting diseases, this Review provides a historical reference text and offers current perspectives on each of the 10 phenotypes of endemic parkinsonism. Knowledge obtained from the study of these disease entities supports the hypothesis that both genetic and environmental factors contribute to the development of neurodegenerative diseases, not only in endemic parkinsonism but also in general. At the same time, this understanding suggests useful directions for further research in this area.

Parkinsonism and motor neuron disorders: Lessons from Western Pacific ALS/PDC

Recognized worldwide as an unusual "overlap" syndrome, Parkinsonism and motor neuron disease, with or without dementia, is best exemplified by the former high-incidence clusters of Amyotrophic Lateral Sclerosis and Parkinsonism-Dementia Complex (ALS/PDC) in Guam, USA, in the Kii Peninsula of Honshu Island, Japan, and in Papua, Indonesia, on the western side of New Guinea. Western Pacific ALS/PDC is a disappearing neurodegenerative disorder with multiple and sometime overlapping phenotypes (ALS, atypical parkinsonism, dementia) that appear to constitute a single disease of environmental origin, in particular from exposure to genotoxins/neurotoxins in seed of cycad plants (Cycas spp.) formerly used as a traditional source of food (Guam) and/or medicine (Guam, Kii-Japan, Papua-Indonesia). Seed compounds include the principal cycad toxin cycasin, its active metabolite methylazoxymethanol (MAM) and a non-protein amino acid β-N-methylamino-L-alanine (L-BMAA); each reproduces components of ALS/PDC neuropathology when individually administered to laboratory species in single doses perinatally (MAM, L-BMAA) or repeatedly for prolonged periods to young adult animals (L-BMAA). Human exposure to MAM, a potent DNA-alkylating mutagen, also has potential relevance to the high incidence of diverse mutations found among Guamanians with/without ALS/PDC. In sum, seven decades of intensive study of ALS/PDC has revealed field and laboratory approaches leading to discovery of disease etiology that are now being applied to sporadic neurodegenerative disorders such as ALS beyond the Western Pacific region. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

Multiple system aging-related tau astrogliopathy with complex proteinopathy in an oligosymptomatic octogenarian

The combination of multiple neurodegenerative proteinopathies is increasingly recognized. Together they can potentiate neuronal dysfunction and contribute to complex neurological symptoms. We report an octogenarian female case of multiple extraneural metastases of a rectal carcinoma. She attempted suicide, which ultimately led to cardiorespiratory failure nine days after hospital admission. Apart from the suicide attempt and late-onset depression, other psychiatric or neurological symptoms were not reported. Unexpectedly, histopathologic examination revealed prominent aging-related tau astrogliopathy (ARTAG) of all five types (subpial, subependymal, grey and white matter, and perivascular) affecting cortical and subcortical brain regions. This pathology was associated with intermediate Alzheimer's disease neuropathologic change (A2B2C2 score), cerebral amyloid angiopathy, Lewy body-type α-synuclein proteinopathy (Braak stage 4), and a multiple system transactivation response DNA-binding protein of 43 kDa (TDP-43) proteinopathy also involving the astroglia. In summary, we report a complex and extensive combination of multiple proteinopathies with widespread ARTAG of all five types in a patient who had attempted suicide. Although longitudinal psychometric tests and neuropsychological evaluations were not performed, this report poses the question of thresholds of cognition and pathology load, describes ARTAG affecting unusually widespread brain regions, and supports the notion that complex proteinopathies should be regarded as a frequent condition in the elderly.

l-Serine Reduces Spinal Cord Pathology in a Vervet Model of Preclinical ALS/MND

The early neuropathological features of amyotrophic lateral sclerosis/motor neuron disease (ALS/MND) are protein aggregates in motor neurons and microglial activation. Similar pathology characterizes Guamanian ALS/Parkinsonism dementia complex, which may be triggered by the cyanotoxin β-N-methylamino-l-alanine (BMAA). We report here the occurrence of ALS/MND-type pathological changes in vervets (Chlorocebus sabaeus; n = 8) fed oral doses of a dry powder of BMAA HCl salt (210 mg/kg/day) for 140 days. Spinal cords and brains from toxin-exposed vervets were compared to controls fed rice flour (210 mg/kg/day) and to vervets coadministered equal amounts of BMAA and l-serine (210 mg/kg/day). Immunohistochemistry and quantitative image analysis were used to examine markers of ALS/MND and glial activation. UHPLC-MS/MS was used to confirm BMAA exposures in dosed vervets. Motor neuron degeneration was demonstrated in BMAA-dosed vervets by TDP-43⁺ proteinopathy in anterior horn cells, by reactive astrogliosis, by activated microglia, and by damage to myelinated axons in the lateral corticospinal tracts. Vervets dosed with BMAA + l-serine displayed reduced neuropathological changes. This study demonstrates that chronic dietary exposure to BMAA causes ALS/MND-type pathological changes in the vervet and coadministration of l-serine reduces the amount of reactive gliosis and the number of protein inclusions in motor neurons.

Synuclein in neurodegeneration

Neurodegenerative diseases are a heterogeneous group of disorders characterized by gradual progressive neuronal loss in the central nervous system. Unfortunately, the pathogenesis of many of these diseases remains unknown. Synucleins are a family of small, highly charged proteins expressed predominantly in neurons. Following their discovery, much has been learned about their structure, function, interaction with other proteins and role in neurodegenerative disease over the last two decades. One of these proteins, α-Synuclein (α-Syn), appears to be involved in many neurodegenerative disorders. These include Parkinson's disease (PD), dementia with Lewy bodies (DLB), Rapid Eye Movement Sleep Behavior Disorder (RBD) and Pure Autonomic Failure (PAF), i.e., collectively termed α-synucleinopathies. This review focuses on α-Syn dysfunction in neurodegeneration and assesses its role in synucleinopathies from a biochemical, genetic and neuroimaging perspective.

Dysfunction of Protein Quality Control in Parkinsonism-Dementia Complex of Guam

Guam parkinsonism–dementia complex (G-PDC) is an enigmatic neurodegenerative disease that is endemic to the Pacific island of Guam. G-PDC patients are clinically characterized by progressive cognitive impairment and parkinsonism. Neuropathologically, G-PDC is characterized by abundant neurofibrillary tangles, which are composed of hyperphosphorylated tau, marked deposition of 43-kDa TAR DNA-binding protein, and neuronal loss. Although both genetic and environmental factors have been implicated, the etiology and pathogenesis of G-PDC remain unknown. Recent neuropathological studies have provided new clues about the pathomechanisms involved in G-PDC. For example, deposition of abnormal components of the protein quality control system in brains of G-PDC patients indicates a role for proteostasis imbalance in the disease. This opens up promising avenues for new research on G-PDC and could have important implications for the study of other neurodegenerative disorders.

'Hummingbird' Sign in a Patient with Guam Parkinsonism-Dementia Complex

We present a case of a 71-year-old male Chamorro patient from Guam who presented with progressive supranuclear palsy (PSP)-Richardson's syndrome. Considering his strong family history of parkinsonism and a PSP phenotype, he was clinically diagnosed with Guam parkinsonism-dementia complex (PDC). Magnetic resonance imaging (MRI) of the brain revealed prominent midbrain atrophy with preserved pontine volume, forming the 'hummingbird' sign, which has not been described before in Guam PDC. Molecular analysis of the chromosome 9 open reading frame 72 gene (C9orf72) showed only 6 GGGGCC repeats. We discuss the clinico-pathological similarities and differences between PSP and Guam PDC, and highlight the topography of neuropathological changes seen in Guam PDC to explain the appearance of the 'hummingbird' sign on MRI.

Symmetric Bihemispheric Postmortem Brain Cutting to Study Healthy and Pathological Brain Conditions in Humans

Neuropathologists, at times, feel intimidated by the amount of knowledge needed to generate definitive diagnoses for complex neuropsychiatric phenomena described in those patients for whom a brain autopsy has been requested. Although the advancements of biomedical sciences and neuroimaging have revolutionized the neuropsychiatric field, they have also generated the misleading idea that brain autopsies have only a confirmatory value. This false idea created a drastic reduction of autopsy rates and, consequently, a reduced possibility to perform more detailed and extensive neuropathological investigations, which are necessary to comprehend numerous normal and pathological aspects yet unknown of the human brain. The traditional inferential method of correlation between observed neuropsychiatric phenomena and corresponding localization/characterization of their possible neurohistological correlates continues to have an undeniable value. In the context of neuropsychiatric diseases, the traditional clinicopathological method is still the best possible methodology (and often the only available) to link unique neuropsychiatric features to their corresponding neuropathological substrates, since it relies specifically upon the direct physical assessment of brain tissues. The assessment of postmortem brains is based on brain cutting procedures that vary across different neuropathology centers. Brain cuttings are performed in a relatively extensive and systematic way based on the various clinical and academic contingencies present in each institution. A more anatomically inclusive and symmetric bi-hemispheric brain cutting methodology should at least be used for research purposes in human neuropathology to coherently investigate, in depth, normal and pathological conditions with the peculiarities of the human brain (i.e., hemispheric specialization and lateralization for specific functions). Such a method would provide a more comprehensive collection of neuropathologically well-characterized brains available for current and future biotechnological and neuroimaging techniques. We describe a symmetric bi-hemispheric brain cutting procedure for the investigation of hemispheric differences in human brain pathologies and for use with current as well as future biomolecular/neuroimaging techniques.

Systemic histiocytosis presenting as macrophagic myofasciitis

A patient with the distinctive pathologic findings of macrophagic myofasciitis (MMF) is presented. This case is similar to patients with MMF first seen in France in 1993. The French group ruled out a histiocytic disorder, and later (1999) reported that this disorder represented an unusual focal reaction to intramuscular injections of vaccines containing aluminum. More recently (2001) symptomatic demyelinating disease was reported in 8 of the 92 patients with MMF who were recognized in France. The present case has thickening of the aortic and mitral valves, a finding not reported by the French group. Whereas the French group ruled out a histiocytic etiology for MMF in their patients, the cardiac findings, along with the innumerable small patchy abnormalities in the supratentorial white matter identified on magnetic resonance imaging (MRI), likely implicate a systemic histiocytic basis for this patient's unique disorder. The importance of an exhaustive workup of the patient with multiple sclerosis with diffuse myalgias is reemphasized.

Globular glial tauopathies (GGT) presenting with motor neuron disease or frontotemporal dementia: an emerging group of 4-repeat tauopathies

A number of recent studies have described cases with tau-positive globular oligodendroglial inclusions (GOIs) and such cases have overlapping pathological features with progressive supranuclear palsy (PSP), but present with clinical features of motor neuron disease (MND) and/or frontotemporal dementia (FTD). These two clinical phenotypes have been published independently and as a result, have come to be considered as distinct disease entities. We describe the clinicopathological and biochemical features of two cases with GOIs: one with clinical symptoms suggestive of MND and the other with FTD. Histological changes in our two cases were consistent with their clinical symptoms; the MND case had severe neurodegeneration in the primary motor cortex and corticospinal tract, whereas the FTD case had severe involvement of the frontotemporal cortices and associated white matter. Immunohistochemistry in both cases revealed significant 4-repeat (4R) tau pathology primarily in the form of GOIs, but also in astrocytes and neurons. Astrocytic tau pathology was morphologically similar to that seen in PSP, but in contrast was consistently negative for Gallyas silver staining. Tau-specific western blotting revealed 68, 64 and 35 kDa bands, showing further overlap with PSP. The underlying neuropathological features of these two cases were similar, with the major difference relating to the regional distribution of pathology and resulting clinical symptoms and signs. The globular nature of glial inclusions and the non-fibrillar properties of tau in astrocytes are characteristic features that allow them to be distinguished from PSP and other tauopathies. We, therefore, propose the term globular glial tauopathy as an encompassing term to classify this emerging class of 4R tauopathy.

Parkinson-dementia complex and development of a new stable isotope dilution assay for BMAA detection in tissue

Beta-methylamino-L-alanine (BMAA) has been proposed as a global contributor to neurodegenerative diseases, including Parkinson-dementia complex (PDC) of Guam and Alzheimer's disease (AD). The literature on the effects of BMAA is conflicting with some but not all in vitro data supporting a neurotoxic action, and experimental animal data failing to replicate the pattern of neurodegeneration of these human diseases, even at very high exposures. Recently, BMAA has been reported in human brain from individuals afflicted with PDC or AD. Some of the BMAA in human tissue reportedly is freely extractable (free) while some is protein-associated and liberated by techniques that hydrolyze the peptide bond. The latter is especially intriguing since BMAA is a non-proteinogenic amino acid that has no known tRNA. We attempted to replicate these findings with techniques similar to those used by others; despite more than adequate sensitivity, we were unable to detect free BMAA. Recently, using a novel stable isotope dilution assay, we again were unable to detect free or protein-associated BMAA in human cerebrum. Here we review the development of our new assay for tissue detection of BMAA and show that we are able to detect free BMAA in liver but not cerebrum, nor do we detect any protein-associated BMAA in mice fed this amino acid. These studies demonstrate the importance of a sensitive and specific assay for tissue BMAA and seriously challenge the proposal that BMAA is accumulating in human brain.

Hippocampal sclerosis with four-repeat tau-positive round inclusions in the dentate gyrus: a new type of four-repeat tauopathy

Hippocampal sclerosis is defined as selective neuronal loss and gliosis of the hippocampus with heterogeneous etiologies, including neurodegenerative tauopathies. We report a 78-year-old woman who presented with depression, in whom postmortem examination revealed almost complete loss of neurons with gliosis in the subiculum and CA1-3 regions of the hippocampus and abundant neuronal cytoplasmic inclusions in the dentate gyrus. The inclusions were round, slightly basophilic and argyrophilic, resembling Pick bodies. However, they were Gallyas- and 4-repeat tau-positive, and 3-repeat tau- and ubiquitin-negative. To our knowledge, the histopathological features in this case were different from those in hippocampal sclerosis or 4-repeat tauopathies reported previously. It is likely that this case is a new variant of 4-repeat tauopathy presenting with hippocampal sclerosis.

Pathological TDP-43 in parkinsonism-dementia complex and amyotrophic lateral sclerosis of Guam

Pathological TDP-43 is the major disease protein in frontotemporal lobar degeneration characterized by ubiquitin inclusions (FTLD-U) with/without motor neuron disease (MND) and in amyotrophic lateral sclerosis (ALS). As Guamanian parkinsonism-dementia complex (PDC) or Guamanian ALS (G-PDC or G-ALS) of the Chamorro population may present clinically similar to FTLD-U and ALS, TDP-43 pathology may be present in the G-PDC and G-ALS. Thus, we examined cortical or spinal cord samples from 54 Guamanian subjects for evidence of TDP-43 pathology. In addition to cortical neurofibrillary and glial tau pathology, G-PDC was associated with cortical TDP-43 positive dystrophic neurites and neuronal and glial inclusions in gray and/or white matter. Biochemical analyses showed the presence of FTLD-U-like insoluble TDP-43 in G-PDC, but not in Guam controls (G-C). Spinal cord pathology of G-PDC or G-ALS was characterized by tau positive tangles as well as TDP-43 positive inclusions in lower motor neurons and glial cells. G-C had variable tau and negligible TDP-43 pathology. These results indicate that G-PDC and G-ALS are associated with pathological TDP-43 similar to FTLD-U with/without MND as well as ALS, and that neocortical or hippocampal TDP-43 pathology distinguishes controls from disease subjects better than tau pathology. Finally, we conclude that the spectrum of TDP-43 proteinopathies should be expanded to include neurodegenerative cognitive and motor diseases, affecting the Chamorro population of Guam.

Similar topographical distribution of neurofibrillary tangles in amyotrophic lateral sclerosis and parkinsonism-dementia complex in people living in the Kii peninsula of Japan suggests a single tauopathy

The presence of many neurofibrillary tangles (NFTs) in the central nervous system is a hallmark of amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia complex (PDC) in people living in the Kii peninsula of Japan and in the island of Guam. To determine whether or not ALS and PDC are on a spectrum of a single tauopathy, we investigated the topography of NFTs semiquantitatively in two patients with ALS, three with PDC, and two with "PDC plus ALS" (PDC followed by ALS) on the basis of clinical symptoms. NFTs were counted under x100 magnification of Gallyas-Braak stained preparations and were plotted on brain maps of the hemisphere, brainstem, and the spinal cord. In all cases, the hippocampus, particularly in the CA1 field, the parahippocampal gyrus, amygdaloid nucleus, and the temporal poles were most severely affected. In the neocortex, layers II-III were more severely affected by NFTs than layers V-VI. In the spinal cord, a few NFTs were revealed in the intermediate gray. NFTs were dense in all cases of PDC and "PDC plus ALS" and variable in density in ALS cases, although the topography was similar between them. We conclude that similar topographical distribution of NFTs in ALS and PDC in people living in the Kii peninsula of Japan suggests a single tauopathy.

Characterization of tau pathologies in gray and white matter of Guam parkinsonism-dementia complex

Guam parkinsonism-dementia complex (PDC) is a neurodegenerative tauopathy in ethnic Chamorro residents of the Mariana Islands that manifests clinically with parkinsonism as well as dementia and is characterized neuropathologically by prominent cortical neuron loss in association with extensive telencephalic neurofibrillary tau pathology. To further characterize cortical gray and white matter tau, alpha-synuclein and lipid peroxidation pathologies in Guam PDC, we examined the brains of 17 Chamorro PDC and control subjects using biochemical and immunohistological techniques. We observed insoluble tau pathology in both gray and white matter of PDC and Guam control cases, with frontal and temporal lobes being most severely affected. Using phosphorylation dependent anti-tau antibodies, abundant tau inclusions were detected by immunohistochemistry in both neuronal and glial cells of the neocortex, while less alpha-synuclein pathology was observed in more limited brain regions. Further, in sharp contrast to Alzheimer's disease (AD), levels of the lipid peroxidation product 8, 12-iso-iPF(2alpha)-VI isoprostane were not elevated in Guam PDC brains relative to controls. Thus, although the tau pathologies of Guam PDC share similarities with AD, the composite Guam PDC neuropathology profile of tau, alpha-synuclein and 8, 12-iso-iPF(2alpha)-VI isoprostane reported here more closely resembles that seen in other tauopathies including frontotemporal dementias (FTDs), which may imply that Guam PDC and FTD tauopathies share underlying mechanisms of neurodegeneration.

Tau-Positive Fine Granules in the Cerebral White Matter: A Novel Finding Among the Tauopathies Exclusive to Parkinsonism-Dementia Complex of Guam

We examined the autopsied brains of cases of 6 types of tauopathy: parkinsonism-dementia complex of Guam (PDC), corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), Pick disease, Alzheimer disease (AD), and myotonic dystrophy together with Guamanian controls. Light microscopy sections of these brains were examined using anti-tau antibodies. Tau-positive fine granules (TFGs) were globe-shaped, and 3 to 6 mum in diameter, were observed predominantly in the frontal white matter in 30 of the 35 patients with PDC. However, no TFGs were found in association with PSP, myotonic dystrophy, Pick disease, AD, or CBD. Western blot analysis of frozen brain tissue taken from the PDC cases revealed that the frontal cortex was hyperphosphorylated and contained 6 tau isoforms (3R+4R tau). However, in the present study, it was revealed that the novel TFGs in the white matter of patients with PDC was composed of 4R tau. Western blot analysis of sarkosyl-insoluble tau from the white matter of the PDC cases showed 2 major bands of 60 and 64 kDa and one minor band of 67 kDa. After dephosphorylation, these bands resolved into one major band of 4-repeat (4R) tau isoform and 3 minor bands of 3-repeat (3R) and 4R tau isoforms. Moreover, the TFGs observed in cases in which the number of neurofibrillary tangles (NFTs) was higher than the threshold level were not correlated with the presence of cortical NFTs. In conclusion, these novel TFGs were found almost exclusively in PDC brains and could therefore be considered as a characteristic neuropathologic marker of this particular tauopathy. The TFGs were hyperphosphorylated tau-positive structures that may be formed by a different mechanism from that used to produce cortical NFTs.

The nature of the parkinsonism-dementia complex and amyotrophic lateral sclerosis of Guam and magnesium deficiency

The parkinsonism-dementia complex (PDC) and amyotrophic lateral sclerosis (ALS) were the fatal neurological diseases, showing very high incidence during 1950-1970 and dramatic decrease after 1970 on Guam. Through the research, the present author insisted that; (1) NFTs in Guam ALS patients are merely a background feature widely dispersed in the population, (2) Guam ALS and PDC are basically different diseases, and (3) Guam ALS occurs initially as classic ALS. As pathogeneses of the diseases, intake of low calcium (Ca) and magnesium (Mg) and high aluminum water and of some plant excitatory neurotoxin has been speculated. To elucidate the pathogenesis, the author performed an experiment exposing rats to low Ca and/or Mg intake for two generations, so as to follow the actual way of human living on the island, since several generations live continuously in the same environment. The study indicates that continuous low Mg intake for two generations induces exclusive loss of dopaminergic neurons in in rats, and may support the Mg hypothesis in the pathogenesis of PDC of Guam.

Clinical grand round: A rapidly progressive pyramidal and extrapyramidal syndrome with a supranuclear gaze palsy

The case history of a patient with a rapidly progressive spastic tetraparesis, pseudobulbar palsy, supranuclear gaze palsy, and extrapyramidal signs is presented. The patient died 17 months after symptom onset, and the differential diagnosis and pathological findings are reviewed.

Genetic epidemiology of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a late onset, rapidly progressive and ultimately fatal neurological disorder, caused by the loss of motor neurons in the brain and spinal cord. Familial aggregation of ALS, with an age-dependent but high penetrance, is a major risk factor for ALS. Familial ALS (FALS) is clinically and genetically heterogeneous. Three genes and linkage to four additional gene loci have been identified so far and may either predominantly lead to ALS (ALSI-ALS6) or cause multisystem neurodegeneration with ALS as an occasional symptom (tauopathies, ALS-dementia complex). This review presents a tentative classification of the "major" ALS genes and ALS "susceptibility" genes, that may act as susceptibility factors for neurodegeneration in interaction with other genetic or environmental risk factors. Considering that mutations in ALS genes explain approximately 10% of familial as well as sporadic ALS, and most remaining cases of the discase are thought to result form the interaction of several genes and environmental factors, ALS is a paradigm for multifactorial discases.

Tau and alpha-synuclein pathology in amygdala of Parkinsonism-dementia complex patients of Guam

Amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) is a progressive neurodegenerative disorder of Chamorro residents of Guam and the Mariana Islands, characterized by abundant neuron loss and tau neurofibrillary pathology similar to that observed in Alzheimer's disease (AD). A variety of neurodegenerative diseases with tau pathology including ALS/PDC also have alpha-synuclein positive pathology, primarily in the amygdala. We further characterized the tau and alpha-synuclein pathology in the amygdala of a large series of 30 Chamorros using immunohistochemical and biochemical techniques. Tau pathology was readily detected in both affected and unaffected Chamorros. In contrast, alpha-synuclein pathology was detected in 37% of patients with PDC but not detected in Chamorros without PDC or AD. The alpha-synuclein aggregates often co-localized within neurons harboring neurofibrillary tangles suggesting a possible interaction between the two proteins. Tau and alpha-synuclein pathology within the amygdala is biochemically similar to that observed in AD and synucleinopathies, respectively. Thus, the amygdala may be selectively vulnerable to developing both tau and alpha-synuclein pathology or tau pathology may predispose it to synuclein aggregation. Furthermore, in PDC, tau and alpha-synuclein pathology occurs independent of beta-amyloid deposition in amygdala thereby implicating the aggregation of these molecules in the severe neurodegeneration frequently observed in this location.

Postencephalitic Parkinson's disease, amyotrophic lateral sclerosis on Guam and influenza revisited: focusing on neurofibrillary tangles and the trail of tau

Circumstantial evidence links neuropathological changes in postencephalitic Parkinson's disease and amyotrophic lateral sclerosis on Guam to the 1918 influenza pandemic. Postencephalitic Parkinson's disease and amyotrophic lateral sclerosis have neuronal neurofibrillary tangles that anatomically correlate with clinical signs and symptoms. Occurrences of the disorders peaked in the early 1950s and are now disappearing. Neurovirulent influenza associated with the lethal 1918 pandemic is suggested as the etiology of both diseases. Permissive tissue antigens are considered an important contributing factor. Neurofibrillary tangles also correlate with signs and symptoms in Alzheimer's disease. Oxidative stress may be the pathological process that induces neurofibrillary tangles. Tangles contain abnormally phosphorylated tau. In Alzheimer's disease, tau is present in cerebrospinal fluid and is deposited in corpora amylacea, demonstrating the direction of cerebrospinal fluid flow.

Glutamate uptake

Brain tissue has a remarkable ability to accumulate glutamate. This ability is due to glutamate transporter proteins present in the plasma membranes of both glial cells and neurons. The transporter proteins represent the only (significant) mechanism for removal of glutamate from the extracellular fluid and their importance for the long-term maintenance of low and non-toxic concentrations of glutamate is now well documented. In addition to this simple, but essential glutamate removal role, the glutamate transporters appear to have more sophisticated functions in the modulation of neurotransmission. They may modify the time course of synaptic events, the extent and pattern of activation and desensitization of receptors outside the synaptic cleft and at neighboring synapses (intersynaptic cross-talk). Further, the glutamate transporters provide glutamate for synthesis of e.g. GABA, glutathione and protein, and for energy production. They also play roles in peripheral organs and tissues (e.g. bone, heart, intestine, kidneys, pancreas and placenta). Glutamate uptake appears to be modulated on virtually all possible levels, i.e. DNA transcription, mRNA splicing and degradation, protein synthesis and targeting, and actual amino acid transport activity and associated ion channel activities. A variety of soluble compounds (e.g. glutamate, cytokines and growth factors) influence glutamate transporter expression and activities. Neither the normal functioning of glutamatergic synapses nor the pathogenesis of major neurological diseases (e.g. cerebral ischemia, hypoglycemia, amyotrophic lateral sclerosis, Alzheimer's disease, traumatic brain injury, epilepsy and schizophrenia) as well as non-neurological diseases (e.g. osteoporosis) can be properly understood unless more is learned about these transporter proteins. Like glutamate itself, glutamate transporters are somehow involved in almost all aspects of normal and abnormal brain activity.

Kii ALS dementia

Epidemiological surveys in the foci of ALS of the Kii Peninsula of Japan started in the early 1960s. Continuous surveys conducted for decades revealed that there have been two foci in the Kii Peninsula: one in Kozagawa in the southern part, and the other in Hobara in the south-east. Clinically, ALS patients of the Kii foci occasionally showed parkinsonian features or dementia that have not been reported in the sporadic form of ALS. Neuropathologically, numerous NFT that are identical to those of Alzheimer's disease were observed in the cerebral cortex and in the brainstem nuclei. To elucidate the etiopathogenesis of this unique form of ALS, an analysis was conducted of the environment in the focus areas and of the specimens from the patients with ALS. It was hypothesized that the long exposure of these environments to low calcium and magnesium, and an excess of aluminum and manganese in the drinking water and the soil, might lead to the deposition of some trace elements in the CNS, eventually causing neuronal degeneration and death.

Substantia nigra in progressive supranuclear palsy, corticobasal degeneration, and parkinsonism-dementia complex of Guam: specific pathological features

Disease-specific findings in the substantia nigra were examined in cases of progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), and parkinsonism-dementia complex of Guam (PDC); diseases in which the patients exhibit dementia and parkinsonism, with neurofibrillary tangles (NFTs) and glial tangles composed of hyperphosphorylated tau. Loss of pigmented neurons was extremely severe in these 3 diseases, and decrease of the nonpigmented neurons was severe in PSP and CBD. On the other hand, in PDC the decrease of the nonpigmented neurons was different in each patient. Topographically, in PSP the nonpigmented neurons were particularly depleted in the ventral part and relative preservation of the pigmented neurons was observed in the medial part at the level examined. Many NFTs were observed in PDC. Although the number of NFTs was small, many pretangles were seen in the neurons in CBD. Granular and hazy astrocytic inclusions were identified exclusively in PDC. Numerous argyrophilic neuropile threads were identified in CBD and PSP, but these were few in PDC. Many foamy spheroid bodies as well as coiled bodies were observed in PSP and CBD, but only a few were observed in PDC. In conclusion, PDC is a disease that is distinctly different from PSP and CBD. It is possible to differentiate between PSP and CBD by the occurrence of many pretangles in CBD, but some similarities between these 2 diseases indicate the existence of common pathological mechanisms.

Alpha-synuclein inclusions in amygdala in the brains of patients with the parkinsonism-dementia complex of Guam

We investigated by immunohistochemistry the deposition of alpha-synuclein in the brains of deceased patients with the parkinsonism-dementia complex (PDC) of Guam. Five of 13 PDC brains showed numerous alpha-synuclein positive neuronal inclusions and abnormal neurites, chiefly in the amygdala. Similar alpha-synuclein positive lesions were observed, although to a lesser extent, in the entorhinal cortex and the dorsal vagal nucleus. No alpha-synuclein positive inclusions were observed in motor cortex or locus coeruleus, and only a small number of positive inclusions were found in the Sommer's sector, temporal cortex, or substantia nigra. Some of the alpha-synuclein positive inclusions were reminiscent of cortical Lewy bodies (LB), but many of those in the amygdala coexisted with tau-positive pretangles and/or neurofibrillary tangles (NFT) within the same neurons. In these neurons, tau-positive shells encapsulated alpha-synuclein positive central cores or irregularly shaped alpha-synuclein-positive deposition intermingled with pretangles/NFT. Thus, the present study suggests that a common mechanism may govern aggregation of alpha-synuclein and tau in the amygdala, and that aggregation of alpha-synuclein may play some role in the neurodegenerative process of a tauopathy (i.e. PDC) in which Abeta deposition is virtually absent.

Gallium-67 scintigraphy in macrophagic myofasciitis

OBJECTIVE

To evaluate gallium-67 (67Ga) uptake and the value of 67Ga scintigraphy for diagnosis of macrophagic myofasciitis (MMF), a recently identified inflammatory myopathy.

METHODS

Twelve consecutive patients with MMF confirmed by muscle biopsy, 10 with polymyositis, 10 with sarcoidosis, 8 with fibromyalgia, and 10 with lymphoma without muscle symptoms (serving as normal controls for muscle) were included. Patients received 1.8 MBq 67Ga per kg body weight by intravenous injection, and scintigraphy was performed with a 2-head gamma camera. The various views were acquired for the 3 main photopeaks of 67Ga 48 hours after infusion, and were analyzed in 2 blinded experiments by nuclear physicians. A semiquantitative scale was used to compare the uptake of 67Ga in the vascular soft tissue background with that in the muscles or joints of MMF patients, and with that in the normal controls.

RESULTS

The MMF patients (4 men and 8 women, mean +/- SD age 47.8 +/- 8.7 years) had chronic myalgia (n = 11; predominantly in the lower limbs), asthenia (n = 10), arthralgia (n = 7), mild muscle weakness (n = 5), and high serum creatine kinase levels (n = 6). All MMF patients had significantly higher levels of 67Ga uptake in the muscle and para-articular areas than that recorded for the soft tissue background and for the controls. Muscle uptake was bilateral, symmetric, and homogeneous, and predominantly localized in the legs. No linear enhancement corresponding to fascias or synovial involvement was observed. In patients with polymyositis, symmetric, but heterogeneous, 67Ga uptake was observed in muscle, but not in the fascia. In patients with sarcoidosis, 67Ga uptake was nodular and heterogeneous in muscle, was not detected in the fascia, and was suggestive of synovial involvement in the joints. The uptake of 67Ga in fibromyalgic patients was similar to that in normal controls and to that in the soft tissue background.

CONCLUSION

MMF is a new condition involving characteristic changes that can be detected by deltoid muscle biopsy. It usually manifests as a weakly specific, chronic arthromyalgic syndrome that predominates in the lower limbs. 67Ga scintigraphy is a noninvasive method that may make it easier to differentiate MMF from fibromyalgia and sarcoidosis.