Biomedical subjects

J Q Trojanowski

Publications and source records attributed to J Q Trojanowski.

At least 19 recordsLinked to original sources

PubMed1992

Lewy bodies contain beta-amyloid precursor proteins of Alzheimer's disease.

To assess the contribution of Alzheimer's disease amyloid proteins to cortical and substantia nigra Lewy bodies (LBs), regions of postmortem brain rich in intraneuronal LBs were examined immunohistochemically. Antibodies to epitopes in domains outside the amyloidogenic beta-amyloid peptide (BAP) in BAP precursor proteins (BAPPs) as well as to the BAP itself were used as probes. These studies showed that only BAPP epitopes outside the BAP were present in substantia nigral and cortical LBs. Thus, non-amyloidogenic domains of BAPPs may be associated with intraneuronal inclusions comprised of neurofilament proteins.

Alzheimer Disease↗

PubMed1992

Phosphorylated high molecular weight neurofilament protein in the peripheral motor, sensory and sympathetic neuronal perikarya: system-dependent normal variations and changes in amyotrophic lateral sclerosis and multiple system atrophy.

Using monoclonal antibody (Ta-51) that specifically binds phosphorylated high molecular weight neurofilament (pNFH) proteins, we investigated the occurrence of perikaryal pNFH in the spinal ventral horn motoneurons, intermediolateral column (ILC) neurons, sympathetic ganglion neurons and dorsal root ganglion (DRG) neurons obtained from patients with amyotrophic lateral sclerosis (ALS) and multiple system atrophy (MSA) and from control cases. In the controls, a system-dependent variation in perikaryal Ta-51 immunoreactivity was observed. Very few ventral horn cells and ILC neurons were stained with Ta-51, while large population of DRG neurons and sympathetic neurons were Ta-51 positive. The incidence of perikaryal immunoreactivity in the ventral horn cells was significantly increased in ALS and MSA. Some ILC neurons in ALS were Ta-51 positive and their incidence was significantly higher than that of the controls. These data suggest that both ILC neurons and ventral horn cells are affected with respect to pNFH metabolism in ALS and MSA. No significant difference was, however, detected in the Ta-51 immunoreactivity of both DRG and sympathetic ganglion neurons in ALS and MSA as compared with the controls.

Adult↗

PubMed1992

Medulloblastomas and related primitive neuroectodermal brain tumors of childhood recapitulate molecular milestones in the maturation of neuroblasts.

We review here recent data that have brought into sharper focus a number of important biological properties of the neoplastic cells in childhood primitive neuroectodermal tumors (PNETs) of the central nervous system (CNS). Studies of this group of tumors, as exemplified by posterior fossa medulloblastomas (MBs), suggest that neoplastic cells in PNETs partially recapitulate stages in the maturation of normal human neuroblasts. These findings may contribute to the elucidation of the mechanisms involved in tumor initiation and progression because oncogenes and antioncogenes appear to exert their effects in a cell type-specific manner that also depends on the maturational state of a given cell. Currently, a large body of data suggests that populations of cells in PNETs (e.g., MBs) exhibit one or more molecular defects in the sequence of maturational events leading to the exit of stem cells or partially committed neuron-like precursors from the cell cycle, followed by their terminal differentiation into neurons. This, together with the orchestrated interactions of as yet unidentified oncogenes and antioncogenes in these PNET cells, may represent a cluster of molecular abnormalities that underly the emergence of the highly malignant phenotype that characterizes childhood PNETs.

Brain↗

PubMed1992

Differences in phosphorylation state of neurofilament proteins in ganglionic and aganglionic bowel segments of children with Hirschsprung's disease.

Hirschsprung's disease is characterized by the absence of enteric neurons in the myenteric and submucosal plexus and the presence of many unmyelinated axons, visible in ganglion like structures, in the aganglionic part of the bowel. In previous studies we showed that the immunoreactivity of a monoclonal antibody (2F11) specific for neurofilament proteins is increased in aganglionic bowel segments. We now investigated whether the increased neurofilament protein staining results from an increase in neurofilament protein immunoreactivity in the aganglionic segment or if it is also related to differences in the phosphorylation state of neurofilament proteins. Bowel resection specimens of patients with Hirschsprung's disease and control patients were investigated by immunohistochemical techniques using a panel of different monoclonal antibodies that are specific for neurofilament proteins and have well known reaction patterns against different phosphorylated epitopes present on two neurofilament proteins, the middle (NF-M) and the high (NF-H) molecular weight subunit. For comparison the specimens were also stained for acetylcholinesterase, neuron-specific enolase (NSE), S-100, and glial fibrillary acidic protein (GFAP). Immunostaining with this panel of antineurofilament-antibodies showed differences in the phosphorylation state of neurofilament proteins in the aganglionic and the ganglionic bowel segments of patients with Hirschsprung's disease. These changes involved the phosphorylation state of these proteins and the ratio of NF-H and NF-M in neurofilament proteins. Staining with NSE and S-100 showed no significant differences between Hirschsprung's disease patients and control patients. We surmise that during the ingrowth and differentiation of hypertrophic axons the composition of neurofilament proteins formed in the aganglionic bowel segment differs from the neurofilament proteins formed in the ganglionic and control bowel segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗

PubMed1992

Sites of synthesis of chromogranins A and B in the human brain.

The sites of synthesis of the chromogranins A and B, and their potential processed peptides, were examined by quantitating the levels of chromogranin A and B mRNA in various regions of the human brain by Northern blot analysis. Chromogranin A and B mRNA expression in the brain is region-specific and confined to grey matter. In situ hybridization histochemistry detected chromogranin A and B mRNA in pyramidal neurons of human cerebral cortex. Cell-specific expression in subpopulations of cerebrocortical neurons suggest that chromogranin A and B gene products may play a role in central neuronal function.

Brain↗

PubMed1992

The disordered neuronal cytoskeleton in Alzheimer's disease.

Evidence continues to accrue in support of the notion that normal adult human tau is converted into the protein subunits of Alzheimer's disease paired helical filaments as a result of the abnormal phosphorylation of tau at aberrant sites. Although the biological consequences of the generation of these abnormal tau derivatives in neurons remain uncertain, it is plausible that this process could destabilize microtubules and have a deleterious effect on the function and survival of neurons. Recent studies that probe the mechanisms whereby normal tau, a component of the neuronal cytoskeleton, undergoes profound alterations to become paired helical filaments in the Alzheimer's diseased brain are discussed.

Alzheimer Disease↗

PubMed1992

Autopsy: cutting away the myths.

Autopsy serves to monitor quality of care, determines means of death in puzzling medical situations and medicolegal cases, documents true disease rates and provides other essential data for registries and research. This article discusses the current status of autopsy, reasons for the declining rate, and myths commonly held by patients and their families. The neuroscience nurse can clarify misperceptions, provide accurate and timely information in a sensitive and articulate manner, and support patients and their families in their decisions about autopsy.

Attitude of Health Personnel↗

PubMed1992

A novel modification of the avidin-biotin complex method for immunohistochemical studies of transgenic mice with murine monoclonal antibodies.

When mouse tissues are probed with murine monoclonal antibodies (MAb) by indirect immunohistochemistry, the secondary antibody detects tissue-bound MAb and irrelevant, endogenous mouse immunoglobulins. The latter are a source of confounding background, especially in diseased tissues. To circumvent this problem, we generated complexes of primary MAb and biotinylated secondary antibodies in vitro for use as antigen-specific probes. After blocking free binding sites in the complexed secondary antibodies with normal mouse serum, the complexes were applied to mouse tissue sections and tissue-bound complexes were visualized with an avidin-biotin detection system. Complexes formed with 12 different rat or mouse MAb were used to probe sections of normal mice, tumor-bearing transgenic mice, and mice with tumor xenografts. The staining patterns produced by these probes reflected the specificity of the MAb in the complexes, and the labeling of irrelevant, endogenous mouse immunoglobulins was reduced substantially. This novel, indirect immunohistochemical method can be exploited to study normal and diseased mouse tissues using a variety of murine MAb.

Animals↗

PubMed1992

Epitope analysis of senile plaque components in the hippocampus of patients with Parkinson's disease.

We conducted an epitope analysis of senile plaque (SP) proteins on hippocampal SPs in patients with Parkinson's disease (PD), using a library of antibodies to proteins implicated in the genesis of hippocampal SPs in Alzheimer's disease (AD). The library included antibodies to the beta-amyloid protein (beta-AP), domains outside the beta-AP in beta-amyloid precursor proteins (beta-APPs), ubiquitin, diverse neuronal cytoskeletal proteins, and polypeptides located mainly in axon terminals. We obtained samples of hippocampus at autopsy from 14 PD patients, 10 of whom were demented. As in the AD hippocampus, the SPs detected by conventional stains in five of the 10 demented subjects contained the beta-AP and flanking domains in beta-APPs as well as epitopes in tau, neurofilament proteins, and synaptophysin. Further, with the exception of the beta-AP, epitopes in the other proteins were confined to the coronas of SPs, while clathrin light chain, microtubule-associated protein 5, and neural cell adhesion molecules were almost undetectable or absent in the neuropil occupied by SPs. The same group of antibodies rarely labeled SPs in the other five demented PD subjects or in the four nondemented PD subjects, and conventional stains for amyloid and neurofibrillary pathology revealed rare SPs in these cases. Hence, when conventional stains reveal lesions diagnostic of AD in PD patients, the molecular features of the hippocampal SPs in these patients are the same as those in SPs of the AD hippocampus.

Aged↗

PubMed1992

Nestin expression in embryonic human neuroepithelium and in human neuroepithelial tumor cells.

Nestin is a recently described member of the intermediate filament (IF) protein family that is especially abundant in neuroepithelial stem cells of the rat. The studies described here examine this class VI IF protein in the normal human developing central nervous system (CNS), human brain tumor-derived cell lines, and tissue samples of human CNS tumors. Human nestin exhibited biochemical and immunochemical properties similar to those of rat nestin. Further, as in the rat, nestin was detected immunohistochemically in several different types of immature human CNS cells, i.e. germinal matrix cells, neuroepithelial cells lining the central canal, radial glia and vascular cells. Nestin appeared in these cells at the earliest gestational age (i.e., 6 weeks) examined here and then it declined in all but the vascular cells at later embryonic stages. Nestin also was detected by immunocytochemistry in 6 of 7 primitive neuroectodermal tumor cell lines and in both of 2 malignant glioma cell lines examined. In these cell lines, nestin co-localized incompletely with bundles of IFs containing other IF proteins (i.e., vimentin, glial filament, neurofilament). Nestin was ubiquitous in a wide variety of brain tumors, but was most prominent in gliomas. The transient expression of nestin in primitive neuroepithelial cells at early stages of human embryogenesis and its abundance in neuroepithelial tumors suggest a role for nestin IFs in cellular events that precede the exit of embryonic CNS stem cells from the cell cycle and the commitment of the progeny of these stem cells to a specific lineage. The subsequent induction of different members of the IF protein family in phenotypically distinct CNS cells (i.e. neurons, glia) and the elimination of nestin from almost all differentiated CNS cells, imply that different classes of IFs subserve functions that are closely linked to the maturational state, as well as the lineage, of CNS cells.

Adolescent↗

PubMed1992

Regions with abundant neurofibrillary pathology in human brain exhibit a selective reduction in levels of binding-competent tau and accumulation of abnormal tau-isoforms (A68 proteins).

Paired helical filaments, the dominant filamentous components of Alzheimer's disease (AD), neurofibrillary tangles (NFT), neuropil threads, and the dystrophic neurites associated with amyloid rich senile plaques, are composed of abnormally phosphorylated derivatives of tau known as A68 proteins. Indeed the inappropriate phosphorylation of Ser396, which is adjacent to the microtuble binding domain in tau, may contribute to the transformation of tau into A68 and prevent A68 from efficiently binding to microtubules. The reduced levels of normal soluble tau proteins in AD brains may be the consequence of a multi-step process whereby normal tau is converted into A68 and sequestered in paired helical filaments. To elucidate the events involved in this process, we compared the relative levels of binding-competent (BC) and binding-incompetent (BI) tau with the level of A68 in six different regions (hippocampus, fornix, frontal grey and white matter, and cerebellar grey and white matter) of fresh AD and control brains. When the AD brains were compared as a group with neurologically normal and diseased non-AD controls, quantitative immunoblot analysis demonstrated a selective reduction of BC tau in regions of the AD brains with abundant neurofibrillary lesions (NFTs, neuropil threads, and senile plaque neurites) and in their associated white matter areas. The level of BI tau was similar in both AD and control brains. In contrast, A68 was present only in the AD brains, but it was confined to those brain regions with abundant NFTs, neuropil threads, and senile plaques. We view the reductions in BC tau in fornix and frontal white matter to be a consequence of the reductions in their associated grey matter regions i.e., hippocampus and frontal grey matter. Although there is no strict relationship between the reduction of BC tau and the level of A68 within an individual brain, the comparison of the AD group with the control group suggests that the grey matter of the affected regions may be the site for the conversion of BC tau into A68. Further, this process may occur rapidly or via pathways that do not involve BI tau since the levels of BI tau were similar in AD and control brains. Although the complete sequence of events leading to the transformation of tau into A68 and paired helical filaments remains to be elucidated, our data provide compelling evidence that A68 proteins are generated from tau-proteins in selected regions of the AD brain where neurofibrillary lesions comprised of paired helical filaments accumulate.

Adult↗

PubMed1991

Abnormal expression of two microtubule-associated proteins (MAP2 and MAP5) in specific subfields of the hippocampal formation in schizophrenia.

A variety of cytoarchitectural disturbances have been described in limbic regions in postmortem studies of schizophrenia, many of which suggest a developmental disturbance of normal neuronal geometry. This geometry is established and maintained by elements of the neuronal cytoskeleton. Immunohistochemistry with a panel of 15 monoclonal antibodies was used to monitor the presence of neuronal cytoskeletal proteins in the hippocampal formations of six patients with schizophrenia, six normal controls, and six with neurodegenerative disorders. In five of the six subjects with schizophrenia, prominent and specific alterations were found in the distribution of two microtubule-associated proteins, MAP2 and MAP5, which were anatomically selective for the subiculum and entorhinal cortex. In contrast, the immunoreactivity of other cytoskeletal proteins (i.e., tau, tubulins, and selected neurofilament protein phosphoisoforms) was similar for all subjects. Defects in the expression of MAP2 and MAP5, two proteins that contribute to the establishment and maintenance of neuronal polarity, could underlie some of the cytoarchitectural abnormalities described in schizophrenia and impair signal transduction in the affected dendrites. The subiculum and entorhinal cortex interconnect the hippocampal formation with widespread cortices and subcortical nuclei and play important roles in higher cognitive functions. Hence, pathologic lesions that distort the polarized geometry of neurons could play a role in the emergence of aberrant behavior in schizophrenia.

Aged↗

PubMed1991

Neurofilament reassembly in vitro: biochemical, morphological and immuno-electron microscopic studies employing monoclonal antibodies to defined epitopes.

The reassembly process of purified native (phosphorylated) and enzymatically dephosphorylated bovine neurofilament (NF) subunits was studied to delineate how NF triplet proteins assemble together into intermediate-size filaments in vitro. We determined the time course for reassembly, the ultrastructural characteristics of reassembled NFs, and the topographical disposition of NF protein subdomains within reassembled NFs using quantitative biochemical techniques, negative staining and immunoelectron microscopy. Our data indicate that: (1) approximately 50% of the purified NF subunit proteins assembled within 30 min from the start of reassembly into 10- to 12-nm filaments, and by 90 min approximately 85-90% of the NF proteins reassembled, (2) low concentrations (0.15-0.5 mg/ml) of purified NF proteins were able to reassemble into long filaments, (3) the rate and ability of native phosphorylated and dephosphorylated NF proteins to assemble into NFs were comparable, (4) negative staining revealed a periodicity of approximately 18-22 nm and a protofilamentous substructure in reassembled NFs, (5) immunoelectron microscopy using domain specific anti-NF monoclonal antibodies (mAbs) to all 3 NF proteins demonstrated specific labeling patterns corresponding to the spatial relationships of subdomains within reassembled NFs, and (6) negative staining and immunolabeling revealed that reassembled NFs are very similar to isolated native NFs. We conclude that purified mammalian axonal NF triplet proteins, independent of their phosphorylation state, rapidly and efficiently reassemble in vitro to generate characteristic 10-nm filaments. Furthermore, immunological analysis reveals that the rod domains of NF-H, NF-M and NF-L are buried within the reassembled NF, whereas the head domain of NF-M and the tail domains of all 3 NF proteins remain exposed following reassembly.

Animals↗

PubMed1991

Molecular milestones that signal axonal maturation and the commitment of human spinal cord precursor cells to the neuronal or glial phenotype in development.

Insights into the programmatic induction of neuronal and glial genes during human embryogenesis have depended largely on extrapolations of data derived from experimental mammals. However, the assumptions upon which these extrapolations are based have not been rigorously tested. Indeed, practically no information is available even on the human counterparts of the relatively small subset of well-characterized, developmentally regulated neuron and glial specific genes of the mammalian CNS. Thus, the developmental programs upon which human neural embryogenesis are based remain largely undeciphered. We have addressed this problem in immunohistochemical studies conducted on 22 human fetal spinal cords with gestational ages (GAs) that ranged from 6 to 40 weeks by using monoclonal antibodies to several classes of neuron or glial specific polypeptides. These polypeptides included: representatives of four different types (Types I-IV) of intermediate filament proteins, i.e., vimentin filament protein (VFP), glial fibrillary acidic protein (GFAP), different phospho-isoforms of the high (NF-H), middle (NF-M), and low (NF-L) molecular weight (Mr) neurofilament (NF) subunits, both acidic and basic cytokeratin (CK) proteins; three different microtubule associated proteins (MAPs), i.e., MAP2, MAP5, and tau; two different synaptic or coated vesicle proteins, i.e., synaptophysin (SYP) and clathrin light chain B (LCb); an oligodendroglial specific protein, i.e., myelin basic protein (MBP); and a receptor for a CNS trophic factor, i.e., the nerve growth factor receptor (NGFR).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1991

Human olfactory epithelium in normal aging, Alzheimer's disease, and other neurodegenerative disorders.

By use of immunohistochemistry, we characterized the molecular phenotype of human olfactory epithelial (OE) cells and assessed the nature of the dystrophic olfactory neurites described initially in Alzheimer's disease (AD). Keratin 8 was present in all classes of OE cells. Sustentacular cells lacked other cell type specific polypeptides and were distinguished from neurons and basal cells because the latter two classes of OE cells expressed neural cell adhesion molecules (N-CAMs) and microtubule associated proteins (MAPs), i.e., MAP5. Basal cells expressed nerve growth factor receptors (NGFRs), which distinguished them from olfactory neurons. Unlike their perikarya, olfactory axons expressed vimentin and GAP-43, but not peripherin or neurofilament (NF) proteins. Olfactory nerves were distinguished from other axons because the latter were positive for all three NF subunits and peripherin, in addition to vimentin and GAP-43. Dystrophic neurites in the OE were GAP-43 positive, but they also expressed proteins that were not detected in normal olfactory nerves (i.e., synaptophysin, MAP2, tau, peripherin, NF proteins). Further, rare NF positive olfactory neurons gave rise to NF positive dystrophic neurites. These neurites were present in all 11 AD cases, 11 of 14 subjects with other neurodegenerative diseases, and 6 of 8 neurologically normal adult controls, but no dystrophic neurites were seen in 9 fetal and neonatal cases. We conclude that the molecular phenotype of different human OE cells is distinct and that dystrophic olfactory neurites occur very frequently in neurologically normal adults. The relevance of these neurites to aging or specific disease processes remains speculative.

Adult↗

PubMed1991

Epitopes located in spatially separate domains of each neurofilament subunit are present in Parkinson's disease Lewy bodies.

Subcortical Lewy bodies are the pathological hallmark of idiopathic Parkinson's disease. This study sought to determine the extent to which each neurofilament subunit [low (NF-L), mid (NF-M), or high (NF-H)] was present in Lewy bodies by using light, confocal, and electron microscopy. A battery of 37 antineurofilament antibodies, characterized as to subunit specificity, epitope domain, and phosphorylation status, was employed to probe substantia nigra Lewy bodies from 15 Parkinson's disease cases. All 37 antibodies labelled Lewy bodies. The epitopes recognized by these antibodies included those in the NF-L rod and tail domains; the NF-M head, rod, and tail domains, as well as epitopes within, and flanking, the multiphosphorylation repeat site; and the NF-H rod domain and multiphosphorylation repeat sites. With these probes, nearly the entire length of each subunit could be demonstrated in Lewy bodies. However, the staining pattern of the Lewy bodies suggested that the tail domains of NF-M and NF-H were present in the periphery of the Lewy body core and in the Lewy body corona, but they appeared to be altered or missing in the center of the Lewy body core. In contrast, the head domain of NF-M, the tail domain of NF-L, and the rod domains of all three subunits are present throughout the Lewy body. These results strongly suggest that the entire extent of each neurofilament subunit is found in Lewy bodies but that the neurofilament subunits may be altered during the processing of these filaments into Lewy bodies.

Aged↗

PubMed1991

A68: a major subunit of paired helical filaments and derivatized forms of normal Tau.

Putative Alzheimer disease (AD)-specific proteins (A68) were purified to homogeneity and shown to be major subunits of one form of paired helical filaments (PHFs). The amino acid sequence and immunological data indicate that the backbone of A68 is indistinguishable from that of the protein tau (tau), but A68 could be distinguished from normal human tau by the degree to which A68 was phosphorylated and by the specific residues in A68 that served as phosphate acceptors. The larger apparent relative molecular mass (Mr) of A68, compared to normal human tau, was attributed to abnormal phosphorylation of A68 because enzymatic dephosphorylation of A68 reduced its Mr to close to that of normal tau. Moreover, the LysSerProVal motif in normal human tau appeared to be an abnormal phosphorylation site in A68 because the Ser in this motif was a phosphate acceptor site in A68, but not in normal human tau. Thus, the major subunits of a class of PHFs are A68 proteins and the excessive or inappropriate phosphorylation of normal tau may change its apparent Mr, thus transforming tau into A68.

Alzheimer Disease↗

PubMed1991

Expression patterns of beta-amyloid precursor protein (beta-APP) in neural and nonneural human tissues from Alzheimer's disease and control subjects.

Both neural and nonneural human tissues from patients with or without Alzheimer's disease (AD) were surveyed to detect the presence of the beta-amyloid protein and its precursors. This was accomplished using polyclonal and monoclonal antibodies to epitopes in the 695 amino acid long beta-APP (i.e., beta-APP695), as well as in related beta-APPs. Immunoreactivity in beta-APP in brain was prominent in senile plaques, extraneuronal tangles, and neurons. Outside the brain, beta-APP staining was seen in neurons and satellite glial cells of the dorsal root, enteric and trigeminal ganglia, the adeno- and neurohypophysis, megakaryocytes, and adrenal gland in samples from patients with AD and those without AD. Western blots of neocortex revealed three major proteins with apparent molecular masses of 105, 115, and 125 kDa in the insoluble membrane-associated fractions, while two broad bands with a molecular weight centered at about 100 and 120 kDa were detected in soluble fractions. In addition, the pituitary and adrenal glands as well as cardiac muscle revealed prominent immunobands in membrane-associated fractions. Notably, other nonneural tissues were devoid of beta-APP immunoreactivity. Thus, the beta-APPs are detectable only in a limited number of nonneural tissues. Taken together, these data suggest that beta-APPs produced in the brain are sources of beta-APP peptides that accumulate as senile plaques in AD.

Alzheimer Disease↗