Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002736 (amyotrophic lateral sclerosis)
 19,048 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Environmental toxins may be risk factors for some forms of diabetes mellitus and neurodegenerative diseases. The medicinal and food use of seed from the cycad plant (Cycas spp.), which contains the genotoxin cycasin, is a proposed etiological factor for amyotrophic lateral sclerosis/Parkinsonism-dementia complex (ALS/PDC), a prototypical neurodegenerative disease found in the western Pacific. Patients with ALS/PDC have a very high prevalence of glucose intolerance and diabetes mellitus (in the range of 50-80%). We investigated whether the cycad plant toxin cycasin (methylazoxymethanol (MAM) beta-D-glucoside) or the aglycone MAM are toxic in vitro to mouse or human pancreatic islets of Langerhans. Mouse pancreatic islets treated for 6 days with cycasin impaired the beta-cell insulin response to glucose, but this effect was reversible after a further 4 days in culture without the toxin. When mouse islets were exposed for 24 hr to MAM/MAM acetate (MAMOAc; 0.1-1.0 mM), there was a dose-dependent impairment in insulin release and glucose metabolism, and a significant decrease in islet insulin and DNA content. At higher MAM/MAMOAc concentrations (1.0 mM), widespread islet cell destruction was observed. Glucose-induced insulin release remained impaired even after removal of MAM and a further culturing for 4 days without the toxin. MAM damages islets by two possible mechanisms: (a) nitric oxide generation, as judged by increased medium nitrite accumulation; and (b) DNA alkylation, as judged by increased levels of O6-methyldeoxyguanosine in cellular DNA. Incubation of mouse islets with hemin (10 or 100 microM), a nitric oxide scavenger, or nicotinamide (5-20 mM) protected beta-cells from a decrease in glucose oxidation by MAM. In separate studies, a 24 hr treatment of human beta-islet cells with MAMOAc (1.0 mM) produced a significant decrease in both insulin content and release in response to glucose. In conclusion, the present data indicate that cycasin and its aglycone MAM impair both rodent and human beta-cell function which may lead to the death of pancreatic islet cells. These data suggest that a "slow toxin" may be a common aetiological factor for both diabetes mellitus and neurodegenerative disease.
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PMID:Cycad toxin-induced damage of rodent and human pancreatic beta-cells. 764 37

The medicinal and food use of seed from the cycad plant (Cycas spp.), which contains the neurotoxin cycasin, is a proposed etiological factor for amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC), a prototypical neurodegenerative disease found in the western Pacific. Cycasin, the beta-D-glucoside of methylazoxymethanol might enter neurons and other cells via a glucose transporter. Since the intestinal brush-border Na+/glucose cotransporter plays a major role in the absorption of monosaccharides, the following studies were conducted to determine if cycasin, the beta-D-glucoside of methylazoxymethanol, is a substrate for the transporter. We measured the ability of cycasin to (i) inhibit Na+/glucose uptake into rabbit intestinal brush-border membrane vesicles, and (ii) to generate current by the cloned Na+/glucose cotransporter (SGLT1) expressed in Xenopus laevis oocytes. The results show that cycasin inhibits Na(+)-dependent sugar transport in the vesicles, and cycasin generates phlorizin-sensitive currents in oocytes. We conclude that cycasin is a substrate for the intestinal brush-border Na+/glucose cotransporter, albeit with a lower affinity than D-glucose. This suggests that cycasin may be absorbed from the gut lumen by the cotransporter, and as a result either cycasin or the aglycone is presented to the blood-brain barrier for uptake into the brain.
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PMID:Transport of cycasin by the intestinal Na+/glucose cotransporter. 803 85

An unusual retinal pigment epitheliopathy resembling ophthalmomyiasis interna posterior (OMI) is endemic to Guam. Sixteen percent of a sample of the indigenous population were found to have the retinopathy. Fifty-two percent of a group of individuals suffering from amyotrophic lateral sclerosis/Parkinsonism-dementia complex (ALS/PDC) were found to have the same retinopathy. Although the retinal appearance is similar to that caused by a subretinal parasite, a definite etiology has not been identified. Three case reports are presented as samples of the clinical presentation of the condition.
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PMID:An unusual retinal pigment epitheliopathy endemic to the island of Guam. 824 90

Apolipoprotein E (Apo E) has been recently identified within amyloid deposits and neurofibrillary tangles in the brains of Alzheimer's disease (AD) patients. A strong association of the Apo E epsilon 4 allele with higher risk of developing AD has also been reported. In the present study, the distribution of Apo E and the possible relationship between Apo E alleles and neuropathological alterations were analyzed in a series of Guamanian amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) cases, a neurodegenerative condition characterized neuropathologically by widespread, severe neurofibrillary tangle formation but rare amyloid deposits. ApoE immunoreactivity was consistently observed in both type of lesions in these cases. Compared to tau protein immunoreactivity, there were generally fewer Apo E-immunoreactive neurofibrillary tangles, particularly in the deep layers of the neocortex and in the hippocampus. Genotype analysis revealed that the epsilon 4 allele frequency was 5.9%, the epsilon 3 allele frequency 88.2%, and the epsilon 2 allele frequency 5.9% in this series. Recent data suggest that the Apo E4 variant may induce amyloidogenesis, while E2 could have a neuroprotective role. However, the rare Guamanian patients with amyloid deposits in cortical areas were not related to the epsilon 4 allele, since all cases with senile plaques were epsilon 3/epsilon 3. In addition, compared to unaffected Guamanian cases and other Asian-Pacific populations previously reported, the observed low frequency of the epsilon 2 allele in the present cases, which may be consistent with the notion that this allele, may represent a neuroprotective factor in several neurodegenerative disorders. The present data indicate that there is a strong interaction between Apo E deposition and neurofibrillary changes in Guamanian ALS-PDC.
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PMID:Apolipoprotein E in Guamanian amyotrophic lateral sclerosis/parkinsonism-dementia complex: genotype analysis and relationships to neuropathological changes. 883 36

Guam Amyotrophic Lateral Sclerosis/Parkinsonism-Dementia Complex (Guam ALS/PDC) is a progressive neurodegenerative disorder characterized by abundant neurofibrillary tangles (NFTs) composed of aggregated paired helical filaments (PHFs). These abnormal filaments resemble the PHFs in neurofibrillary lesions of classic Alzheimer's disease (AD), and recent studies demonstrated that tau in Guam ALS/PDC is aberrantly phosphorylated and biochemically similar to the abnormal tau proteins (PHFtau) in classic AD. However, unlike PHFtau in AD, there is little information on the specific sites of phosphorylation in PHFtau from Guam ALS/PDC. Thus, to address this important issue, we examined tangle-rich Guam ALS/PDC and AD brains by Western blot, immunoelectron microscopy and immunohistochemistry using 13 antibodies to defined phosphate-dependent or -independent epitopes distributed throughout AD PHFtau. These studies identified 7 previously unknown sites of phosphorylation in PHFtau from Guam ALS/PDC (i.e. Thr181, Thr231, Ser262, Ser396, Ser404, Ser422, and the site defined by monoclonal antibody AT10), all of which also are found in AD PHFtau. Indeed, the Western blot, light and immunoelectron microscopic data suggest that NFTs, PHFs and PHFtau in Guam ALS/PDC are very similar to their counterparts in classic AD. Thus, insights into mechanisms leading to the accumulation of neurofibrillary lesions in Guam ALS/PDC may advance understanding of the pathogenesis and biological consequences of these lesions in classic AD.
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PMID:Identification of phosphorylation sites in PHF-TAU from patients with Guam amyotrophic lateral sclerosis/parkinsonism-dementia complex. 885 2

We examined 50 patients with parkinsonism-dementia complex of Guam (Guam PDC), 10 Guamanian patients with amyotrophic lateral sclerosis (ALS), 5 patients with combined PDC and ALS (PDC-ALS), and 20 non-PDC non-ALS Guamanians, who had been autopsied between 1979 and 1982, paying special attention to glial inclusions. Gallyas-positive and tau-immunopositive intracytoplasmic inclusions were observed in many of the glial cells, in addition to extensive neurofibrillary tangles (NFTs) in the brains of Guam PDC and PDC-ALS patients. Granular hazy inclusions were seen in the astrocytes, and some crescent/coiled inclusions were observed in the oligodendroglia. Many granular hazy inclusions were observed in the amygdaloid nucleus, inferior olivary nucleus, and lateral funiculus of the spinal cord. The crescent/coiled inclusions were observed predominantly in the anterior nucleus of the thalamus, motor cortex, midbrain tegmentum, pyramids of the medulla oblongata, and lateral funiculus of the spinal cord. The granular hazy inclusions have never been reported previously, and the topographic distribution of the crescent/coiled inclusions in Guam PDC and PDC-ALS differs from those reported previously in other NFT-forming diseases. These findings indicate that Guam PDC and PDC-ALS involve not only neurons but also glia, and that their morphological and topographic differences from other NFT-forming diseases may provide further insights into their distinct etiopathogenesis, and thus prove useful for diagnosis.
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PMID:Distinct pathological features of the gallyas- and tau-positive glia in the Parkinsonism-dementia complex and amyotrophic lateral sclerosis of Guam. 905 45

This report concerns an investigation on ubiquitin immunoreactivity in the neuronal perikarya of hippocampal granular cells in Guamanian amyotrophic lateral sclerosis (G-ALS) and Guamanian parkinsonism-dementia complex (G-PDC). Specimens from two non-Guamanian cases of ALS with dementia (ALS-D) were included for comparison. Histologically normal hippocampi from five adults served as controls. Antibodies to ubiquitin and tau protein were used throughout. Most Guamanian patients examined had granular cells with perikaryal ubiquitin immunoreactivity in the dentate gyrus, but in comparison to ALS-D, the frequency of ubiquitin-positive neurons was significantly lower. Tau-positive granular cells were detected in most Guamanian patients, but not in ALS-D. There was a relationship between the numbers of ubiquitin-positive and tau-positive neurons in the dentate granular cell layer of G-ALS and G-PDC patients. This was verified on sections double immunostained for tau protein and ubiquitin. The present findings suggest that the ubiquitin-positive materials observed in the perikarya of the dentate granular cells of patients with G-ALS or with G-PDC seem to be Alzheimer's neurofibrillary tangles rather than the typical ubiquitin-positive intracytoplasmic neuronal inclusions, characteristics of ALS-D. Our data would indicate that different mechanisms are involved in the geneses of cortical neuronal degeneration and decline in cognitive function in ALS-D, G-ALS and G-PDC.
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PMID:Comparative study of ubiquitin immunoreactivity of hippocampal granular cells in amyotrophic lateral sclerosis with dementia, Guamanian amyotrophic lateral sclerosis and Guamanian parkinsonism-dementia complex. 908 58

The Guamanian amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) is characterized by abundant neurofibrillary pathology and neuron loss. In contrast to Alzheimer's disease (AD), where extensive neurofibrillary lesions always occur with deposits of A beta in numerous amyloid plaques, A beta-rich amyloid plaques are absent or rare in most ALS/PDC patients. To characterize the amyloid plaques in the latter patients, we probed plaque-rich sections of their brains by immunohistochemistry using well-characterized antibodies to specific epitopes in the N and C termini of A beta as well as to defined epitopes in hyperphosphorylated tau (PHFtau). The results indicate that the species of A beta in the amyloid plaques of ALS/PDC patients resemble those detected in the amyloid plaques of cognitively intact subjects with pathological aging as well as patients with AD. However, the paucity of PHFtau-positive neurites in the ALS/PDC plaques suggests that they reflect pathological aging rather than AD.
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PMID:Amyloid plaques in Guam amyotrophic lateral sclerosis/parkinsonism-dementia complex contain species of A beta similar to those found in the amyloid plaques of Alzheimer's disease and pathological aging. 949 44

Neuronal inclusions with bundles of abnormal filaments made of tau polymers are found in numerous diseases with neurofibrillary degeneration. Tau proteins are the basic components of paired helical filaments (PHF) in Alzheimer's disease (AD), and are abnormally phosphorylated. A disease-specific phosphorylation site at serine422 was demonstrated on PHF, but not on tau proteins from biopsy-derived brain samples. In the present study, we report the characterization of a polyclonal antibody (988) against the serine422 phosphorylation site. By using biochemical and immunohistochemical methods, we confirmed that it is not found on tau proteins from biopsy- or autopsy-derived control samples, and we investigated the presence of this epitope on tau proteins in several neurodegenerative disorders, including AD, Down syndrome (DS), Guamanian amyotrophic lateral sclerosis/Parkinsonism-dementia complex (ALS/PDC), corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), postencephalitic parkinsonism (PEP) and Pick's disease (PiD). By Western blotting, antibody 988 labeled the characteristic tau triplet (tau 55, 64, 69) in AD, DS, Guamanian ALS/PDC and PEP. PSP and CBD exhibited their typical tau doublet (tau 64, 69), whereas the doublet tau 55 and 64 was detected in PiD. In all of these neurodegenerative disorders, antibody 988 clearly labeled NFT and dystrophic neurites, as well as Pick bodies in PiD cases, whereas no staining was observed in control cases. These data indicate that phosphorylation of serine422 on tau proteins is a common feature among neurodegenerative disorders and is therefore not specific of AD. Moreover, phosphorylation of this epitope permits the distinction between normal tau proteins and pathological tau proteins.
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PMID:Phosphorylated serine422 on tau proteins is a pathological epitope found in several diseases with neurofibrillary degeneration. 1009 Jun 68

It is generally agreed that ALS/PDC is triggered by a disappearing environmental factor peculiar to the lifestyle of people of the western Pacific (i.e., Guam, Irian Jaya, Indonesia, and the Kii Peninsula of Japan). A strong candidate is the cycad plant genotoxin cycasin, the beta-D-glucoside of methylazoxymethanol (MAM). We propose that prenatal or postnatal exposure to low levels of cycasin/MAM may damage neuronal DNA, compromise DNA repair, perturb neuronal gene expression, and irreversibly alter cell function to precipitate a slowly evolving disease ("slow-toxin" hypothesis). In support of our hypothesis, we have demonstrated the following: 1. DNA from postmitotic rodent central nervous system neurons is particularly sensitive to damage by MAM. 2. MAM reduces DNA repair in human and rodent neurons, whereas DNA-repair inhibitors potentiate MAM-induced DNA damage and toxicity in mature rodent nervous tissue. 3. Human neurons (SY5Y neuroblastoma) that are deficient in DNA repair are susceptible to MAM-induced cytotoxicity and DNA damage, whereas overexpression of DNA repair in similar cells is protective. 4. MAM alters gene expression in SY5Y human neuroblastoma cells and, in the presence of DNA damage and reduced DNA repair, enhances glutamate-modulated expression of tau mRNA in rat primary neurons; the corresponding protein (TAU) is elevated in ALS/PDC and Alzheimer's disease. These findings support a direct relationship between MAM-induced DNA damage and neurotoxicity and suggest the genotoxin may operate in a similar manner in vivo. More broadly, a combination of genotoxin-induced DNA damage (via exogenous and/or endogenous agents) and disturbed DNA repair may be important contributing factors in the slow and progressive degeneration of neurons that is characteristic of sporadic neurodegenerative disease. Preliminary studies demonstrate that DNA repair is reduced in the brain of subjects with western Pacific ALS/PDC, ALS, and Alzheimer's disease, which would increase the susceptibility of brain tissue to DNA damage by endogenous/exogenous genotoxins. Interindividual differences in the extent of prior exposure to DNA-damaging agents and/or the efficiency of its repair might produce population variety in the rate of damage accumulation and explain the susceptibility of certain individuals to sporadic neurodegenerative disease. Studies are underway using DNA-repair proficient and deficient neuronal cell cultures and mutant mice to explore gene-environment interplay with respect to MAM treatment, DNA damage, and DNA repair, and the age-related appearance of neurobehavioral and neuropathological compromise.
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PMID:Damage and repair of nerve cell DNA in toxic stress. 1046 42


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