Alpha-synuclein in Lewy bodies.
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Humans↗
Biomedical subjects
M L Schmidt
Publications and source records attributed to M L Schmidt.
Autosomal dominant dementia with widespread neurofibrillary tangles.
Several familial dementing conditions with atypical features have been characterized, but only rarely is the neuropathology dominated solely by neurofibrillary lesions. We present a Midwestern American pedigree spanning four generations in which 15 individuals were affected by early-onset dementia with long disease duration, with an autosomal dominant inheritance pattern, and with tau-rich neurofibrillary pathology found in the brain post mortem. The average age at presentation was 55 years with gradual onset and progression of memory loss and personality change. After 30 years' disease duration, the proband's neuropathologic examination demonstrated abundant intraneuronal neurofibrillary tangles (NFTs) involving the hippocampus, pallidum, subthalamic nucleus, substantia nigra, pons, and medulla. Only sparse neocortical tangles were present and amyloid plaques were absent. The tangles were recognized by antibodies specific for phosphorylation-independent (Tau-2, T46, 133, and Alz-50) and phosphorylation-dependent epitopes (AT8, T3P, PHF-1, 12E8, AT6, AT18, AT30) in tau proteins. Electron microscopy of NFTs in the dentate gyrus and midbrain demonstrated paired helical filaments. Although the clinical phenotype resembles Alzheimer's disease, and the neuropathologic phenotype resembles progressive supranuclear palsy, an alternative consideration is that this familial disorder may be a new or distinct disease entity.
Age of Onset↗
Monoclonal antibodies to purified cortical Lewy bodies recognize the mid-size neurofilament subunit.
Lewy bodies (LBs) are filamentous intraneuronal inclusions that are hallmark lesions of Parkinson's disease, and LBs have been shown, by immunohistochemistry, to contain cytoskeletal as well as other cellular proteins. Similar LBs also occur in the cortical neurons of a subset of patients with Alzheimer's disease (AD), and cortical LBs are the predominant or sole lesions in the brains of patients with an AD-like dementia known as diffuse Lewy-body disease (DLBD). To gain insight into the biochemical composition of LBs, we generated monoclonal antibodies (mAbs) to LBs purified from the brains of patients with DLBD. Here, we describe three of these new mAbs (LB48, LB202, and LB204) that stained LBs by immunohistochemistry and recognized the medium molecular mass neurofilament (NF) protein in western blots. These results support the hypothesis that NF subunits are integral components of LBs. Continued efforts to clarify the composition of LBs are likely to lead to novel strategies for the antemortem diagnosis of LB disorders as well as to insight into the role LBs play in the degeneration of affected neurons in these disorders.
Antibodies, Monoclonal↗
Modulation of N-myc expression alters the invasiveness of neuroblastoma.
N-myc oncogene expression plays a pivotal role in the biology of neuroblastoma, a common childhood tumor. High N-myc expression is associated with advanced disease stage, and in animal models, increased expression results in increased metastatic potential. In normal embryologic development, N-myc expression is associated with neuroblast migration out from the neural crest. To further define the relationship between N-myc and metastasis, an in vitro assay was adapted to measure tumor cell attachment, motility, and proteolytic ability in neuroblastoma cell lines. These parameters were examined in a non-amplified, uniformly N-myc overexpressing cell line and its anti-sense N-myc expressing clones. These lines have been characterized previously, and have a decrease in N-myc expression, growth rate, and tumorigenicity relative to the parent line and vector-only control transfectant. Decrease in N-myc expression resulted in a non-proportional increase of tumor cell attachment, and a proportional decrease in both tumor cell motility and proteolytic ability. In further experiments, assay of a N-myc-amplified overexpressing cell line with an intrinsic heterogeneous pattern of expression demonstrated that motile cells expressed higher amounts of N-myc relative to the general population. Together these relationships indicate that N-myc plays a causative role in the invasive phenotype, and suggest that metastasis may, in part, result from the disruption of a developmentally important normal process.
Cell Adhesion↗
Monoclonal antibodies to a 100-kd protein reveal abundant A beta-negative plaques throughout gray matter of Alzheimer's disease brains.
Here we describe the initial characterization of a 100-kd protein recognized by four new monoclonal antibodies that reveal abundant and unique plaque-like lesions throughout gray matter of Alzheimer's disease brains. This 100-kd protein and these new plaque-like lesions were identified by four monoclonal antibodies raised to immunogens extracted from Alzheimer's disease neurofibrillary abnormalities. However, these antibodies did not recognize hyperphosphorylated tau in Western blots or neurofibrillary lesions by immunohistochemistry. As all of these antibodies displayed similar properties, one, AMY117, was used to characterize the new plaque-like lesions in detail. These studies demonstrated that AMY117-positive plaques were not visualized by amyloid stains and never co-localized with A beta deposits, although AMY117-positive and A beta-positive lesions frequently occurred in the same cortical and subcortical gray matter regions. Abundant AMY117-positive plaques were found in the brains of all 32 sporadic Alzheimer's disease patients and all 6 elderly Down's syndrome subjects. Although AMY117-positive plaques also were seen in the brains of nondemented patients with numerous A beta deposits. AMY117-positive plaques were rare or absent in the brains of other elderly controls and patients with other neurodegenerative or neuropsychiatric disorders. We conclude that the AMY117-positive plaques described here for the first time are major lesions of the Alzheimer's disease brain. Thus, it will be important to elucidate the role played by the 100-kd protein and the AMY117 plaques in the etiology and pathogenesis of Alzheimer's disease.
Aged↗
Desmoplastic infantile astrocytoma with metastases at presentation.
A 4-month-old child presented with nystagmus and macrocephaly. He had a large tumor in the suprasellar and hypothalamic region, as well as two smaller similar masses in the posterior fossa and one in the spinal canal. A biopsy of the suprasellar mass revealed it to be a desmoplastic infantile cerebral astrocytoma. Cerebrospinal fluid obtained at surgery before tumor manipulation showed clusters of malignant cells immunopositive for glial fibrillary acidic protein. In our opinion, the smaller tumors were metastases from the large suprasellar primary astrocytoma. Review of all of the previously reported cases of desmoplastic infantile cerebral astrocytoma and of the related neoplastic entity desmoplastic infantile ganglioglioma suggested that this was a unique case, but we still recommend caution with respect to the previously accepted notion that desmoplastic infantile neuroepithelial tumors are virtually benign neoplasms.
Astrocytoma↗
Convergence of Lewy bodies and neurofibrillary tangles in amygdala neurons of Alzheimer's disease and Lewy body disorders.
Amygdalae of patients with Alzheimer's disease (AD), Parkinson's disease, Down's syndrome, diffuse Lewy body disease or a combination of these diseases were probed with antibodies to neurofilament proteins as well as with Lewy body (LB)- and paired helical filament-specific antibodies. The results indicate that the amygdala is severely affected by the accumulation of both neurofibrillary tangles (NFTs) and LBs in most cases of the diseases mentioned above, and that amygdala LBs have a similar epitope composition to that of LBs in the brain stem and cerebral cortex. While large numbers of both LBs and NFTs were seen in different neurons within the amygdala, these two lesions frequently occurred together in the same neurons of the amygdala. These findings are in contrast to other sites that accumulate LBs and NFTs, but rarely both lesions in the same neuron. Thus, amygdala neurons may be selectively vulnerable to developing both LBs and NFTs, and these inclusions may play a role in the massive degeneration of these neurons in AD and LB disorders of the elderly.
Aged↗
Neurofibrillary tangles in progressive supranuclear palsy contain the same tau epitopes identified in Alzheimer's disease PHFtau.
Neurofibrillary tangle (NFT)-rich brain samples from patients with progressive supranuclear palsy (PSP) or Alzheimer's disease (AD) were probed with a large panel of anti-tau antibodies to compare the species of tau present in PSP and AD NFTs by immunohistochemistry and Western blot methods. These antibodies have been shown to recognize phosphate-independent or -dependent epitopes that extend from the amino to the carboxy terminal domains of normal brain tau and the abnormal tau in the paired helical filaments (PHFs) of AD NFTs (PHFtau). The immunohistochemical studies showed that all of the tau epitopes detected in brainstem PSP NFTs also were found in hippocampal AD NFTs and vice versa. While Western blots demonstrated 2 PHFtau-like immunobands in PSP brainstem, a triplet of PHFtau proteins were seen in the AD and PSP hippocampus. Despite differences in the distribution, ultrastructure and immunoblot profile of NFTs in PSP and AD, the same constellation of tau epitopes is present in the abnormal tau proteins in PSP and AD NFTs. Thus, the generation of abnormal tau proteins in PSP (PSPtau) and AD (PHFtau) may have similar adverse biological consequences in both diseases.
Aged↗
Identification of phosphorylation sites in PHF-TAU from patients with Guam amyotrophic lateral sclerosis/parkinsonism-dementia complex.
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.
Aged↗
Association of apolipoprotein epsilon 4 allele and neuropathologic findings in patients with dementia.
Apolipoprotein E (APOE) is a lipoprotein expressed in liver and brain as one of three isoforms (APOE 2, APOE 3 and APOE 4). Recent findings suggest that the presence of APOE 4 is associated with an increased risk for both familial Alzheimer's disease and late-onset Alzheimer's disease. We extended these observations by determining the frequency of APOE alleles in patients with pathologically confirmed Alzheimer's Disease (AD), Parkinson's disease (PD), diffuse Lewy Body disease (DLBD), AD with concomitant PD pathology, demented PD patients without or with concomitant AD pathology and in schizophrenics with a progressive dementia (SCHIZ+DEM). The APOE genotype was determined by restriction digestion of polymerase chain reaction-amplified DNA isolated from frozen brain samples. The frequency of the APOE epsilon 4 allele was highest among sporadic AD and DLBD patients (0.30 and 0.38, respectively) and lowest in the SCHIZ+DEM and non-demented PD patients (0.06 and 0.1, respectively). Thus, the APOE epsilon 4 allele is over-represented selectively in patients with dementias associated with plaques and tangles and/or cortical Lewy bodies, but not in demented schizophrenics or non-demented PD patients.
Aged↗
Paired helical filament tau (PHFtau) in Niemann-Pick type C disease is similar to PHFtau in Alzheimer's disease.
Niemann-Pick Type C disease (NPC) is a cholesterol storage disease with defects in the intracellular trafficking of exogenous cholesterol derived from low density lipoproteins. In NPC cases with a chronic progressive course, neurofibrillary tangles (NFTs) that consist of paired helical filaments (PHFs) have been reported. To determine if NPC tangles contain abnormal tau proteins (known as PHFtau) similar to those found in Alzheimer's disease (AD) tangles, we examined the brains of five NPC cases by immunohistochemical and Western blot methods using a library of antibodies to defined epitopes of PHFtau. We show here that PHFtau in tangle-rich NPC brains is indistinguishable from PHFtau in AD brains. We speculate, that the generation of PHFtau in NPC may induce a cascade of pathological events that contribute to the widespread degeneration of neurons, and that these events may be similar in NPC and AD.
Adult↗
Immunohistochemical detection of the effects of toxic injury on the central nervous system.
Immunohistochemistry currently is the most powerful tool to identify specific molecules in situ. Moreover, antibodies can detect modifications of cellular polypeptides that occur naturally or as a result of toxic or other injuries. Here we report on a variety of parameters (fixation, tissue pretreatments, chromagen intensification, etc.) that we found to enhance immunohistochemical staining. Further, the use of well characterized antibodies and concomitant immunoblotting help avoid false positive results in immunohistochemistry. Finally, the sensitivity of the immunohistochemical procedure, regional differences in immunostaining within the central nervous system, as well as the recognition of equivalent molecules across different animal species are discussed.
Animals↗
Chemical and immunological heterogeneity of fibrillar amyloid in plaques of Alzheimer's disease and Down's syndrome brains revealed by confocal microscopy.
Amyloid beta peptides (A beta) are deposited in the brains of Alzheimer's disease (AD) and elderly Down's syndrome (DS) patients in a variety of amyloid plaques. Among these are classical plaques composed of a spherical core and corona. Analyzing AD tissue sections single and double stained with anti-A beta antibodies and thioflavin S (thioS) by bright field, fluorescence, and confocal microscopy revealed that spherical plaque cores consist of a thioS-positive center and an anti-A beta antibody immunoreactive rim. This indicates that there is a fibrillar form of amyloid that is thioS positive but not immunoreactive with anti-A beta antibodies. In contrast, classical plaques in DS patients have irregular cores that are thioS positive as well as anti-A beta immunoreactive. In addition, a subset of plaques in both DS and AD patients have a distinct "fibrous" appearance when stained with thioS, but are amorphous when immunostained. These findings suggest that anti-A beta antibodies and thioS stain similar; as well as different forms of fibrillar amyloid. A beta may become thioS positive by interacting with one or more of its known molecular chaperons, and this may be important for the pathogenesis of AD, given that thioS-positive A beta deposits are associated with neuritic and synaptic damage.
Aged↗
An extensive network of PHF tau-rich dystrophic neurites permeates neocortex and nearly all neuritic and diffuse amyloid plaques in Alzheimer disease.
Previous studies demonstrated paired helical filament tau (PHF tau) in neuritic but not diffuse beta-amyloid (A beta) plaques in Alzheimer's disease (AD). Re-examination of amyloid deposits with antibodies to A beta and PHF tau by conventional and confocal microscopy using double label immunohistochemistry showed that PHF tau is a component of both diffuse and neuritic plaques in AD. Unlike controls, a dense network of PHF tau positive dystrophic neurites extended throughout the AD neocortex permeating nearly all neuritic and diffuse plaques. Thus, PHF tau-rich dystrophic neurites are common components of neuritic and diffuse plaques in AD neocortex.
Aged↗
Recombinant activated factor VII (rFVIIa) therapy for intracranial hemorrhage in hemophilia A patients with inhibitors.
We report the use of recombinant VIIa (rFVIIa) in the treatment of five ICHs in two factor VIII-deficient patients with inhibitors. In four of five ICHs, rFVIIa was the only factor replacement used at doses of 60-135 micrograms/kg every 2-4 hr for 12-14 days. Hemostasis at the primary site of bleeding was achieved in all cases, and all patients survived with no permanent neurologic deficits. However, the patient who received the highest dose of rFVIIa during the first 4 days of therapy developed clinical symptoms consistent with a cerebral vascular accident of the brainstem characterized by acute onset of truncal ataxia and upward-gaze nystagmus on day 8 of rFVIIa therapy. While receiving rFVIIa therapy for treatment of these five ICHs, four treatment courses were complicated by bleeding at sites other than the primary site, including two episodes of localized oozing at central line insertion sites, two episodes of hemarthrosis, and two episodes of epistaxis. Antifibrinolytic therapy with tranexamic acid was effective in two of these episodes. Laboratory evaluation revealed shortening of the PT, variable shortening without normalization of the APTT, peak factor VII activity levels 7-30-fold higher than normal baseline values, and normal antithrombin III (ATIII) and alpha 2-antiplasmin levels. In four of five ICHs, there was a 20-40% decrease in fibrinogen levels from baseline. The decrease in fibrinogen was accompanied by an increase in fibrin degradation products in 3/5 episodes and a 15-35% decrease in plasminogen activity levels in 2/5 episodes. Tissue factor pathway inhibitor (TFPI) levels remained stable and in the normal range. Although rFVIIa is an effective new therapy for the treatment of ICH in hemophilia patients with inhibitors, its optimal use with respect to safety and efficacy requires further clinical study.
Cerebral Hemorrhage↗
Calcineurin immunoreactivity in Alzheimer's disease.
Aberrant phosphorylation of tau is linked to formation of the paired helical filaments (PHF) seen in Alzheimer's disease. Protein kinases such as mitogen-activated protein kinase, and calcium-regulated protein kinases may, in part, be responsible for addition of phosphate groups to serine residues of PHFtau; however, less is known concerning the phosphatases which regulate tau. In this report, we used several well-characterized antibodies to document calcineurin immunoreactivity in brain tissue from patients with Alzheimer's disease. We now report that levels of immunoreactive calcineurin are not significantly altered in neocortex and cerebellum of Alzheimer's patients relative to similar regions of age-matched controls. Immunocytochemical studies indicated that calcineurin immunoreactivity was present in dendrites and perikarya of many different neuronal populations in both control and Alzheimer brain. When specific antibodies against PHFtau were used in double-labeling experiments with anti-calcineurin antibodies, calcineurin immunoreactivity was seen in association with neurofibrillary tangles. However, calcineurin was not seen in all tangle bearing neurons. These data suggest that calcineurin levels per se are not significantly altered in Alzheimer's disease, but that calcineurin is distributed around some neurofibrillary tangles and may play a role in regulation of tau phosphorylation.
Aged↗
Plaque-associated neuronal proteins: a recurrent motif in neuritic amyloid deposits throughout diverse cortical areas of the Alzheimer's disease brain.
Diffuse and neuritic plaques are sites of accumulation of beta-amyloid peptides (A beta) in the brains of Alzheimer's disease (AD) patients. Although amyloid fibrils are formed from A beta, the contribution of other plaque-associated proteins and peptides to the pathogenesis of AD amyloidosis is unknown. To pursue this issue, we sought to identify proteins and peptides that were consistently associated with neuritic plaques in six different cortical areas of AD and control brains. We accomplished this by using quantitative, single and double label immunohistochemistry and a panel of antibodies to proteins or peptides that are known to be associated with neuritic plaques in the AD hippocampus. Our data showed that the molecular composition of neuritic plaques in association, limbic, sensory, and motor cortex was similar regardless of the type of cortex in which they were found or the apolipoprotein E genotype of the patient. Further, proteins and peptides associated with neuritic plaques in the cortical areas of the AD brain studied here were similar to those found in neuritic plaques of the AD hippocampus. Specifically, in addition to A beta 1-40 and A beta 1-42, these plaques contained immunoreactivity for other domains in A beta precursor proteins, neurofilament and tau proteins, as well as phosphotyrosine residues. We conclude that the recurrent association of a distinct group of neuronal and other proteins and peptides with neuritic plaques suggests that these plaque-associated components play a mechanistic role in the pathogenesis of amyloidosis in AD.
Aged↗
Immunoreactivity profile of hippocampal CA2/3 neurites in diffuse Lewy body disease.
Ubiquitin-immunoreactive dystrophic neurites in the CA2/3 region of the hippocampus are characteristic of diffuse Lewy body disease (DLBD). The origin of dystrophic CA2/3 neurites is unknown, but their extent correlates with the number of cortical Lewy bodies (LBs). To examine the molecular composition of these lesions, hippocampal sections were obtained at postmortem from cases of DLBD, Parkinson's disease and Alzheimer's disease. The tissue samples were fixed in a variety of fixatives and immunostained with antibodies to ubiquitin, ubiquitin C-terminal hydrolase (PGP9.5), neurofilament protein subunits, tau protein, paired helical filaments and tyrosine hydroxylase (TH). In addition to being ubiquitin positive, both cortical LBs and CA2/3 dystrophic neurites were positive with a neurofilament monoclonal antibody (RM032) and PGP9.5; however, fewer lesions were detected with these antibodies compared to ubiquitin immunocytochemistry. The dystrophic CA2/3 neurites were not stained with antibodies to tau proteins, paired helical filaments or TH. Absence of TH immunoreactivity suggests that CA2/3 neuritic processes are not derived from brain stem dopaminergic afferents to the hippocampus. Since CA2/3 neurites are immunologically similar to cortical LB, the pathogenesis of these lesions may be similar. Characterization of dystrophic CA2/3 neurites and cortical LBs may clarify how these lesions contribute to the emergence of dementia in DLBD.
Alzheimer Disease↗