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Biomedical subjects

H M Schipper

Publications and source records attributed to H M Schipper.

At least 37 records · Page 2Linked to original sources
PubMed1998

Experimental induction of corpora amylacea in adult rat brain.

Corpora amylacea (CA) are glycoproteinaceous inclusions that accumulate in astroglia and other brain cells as a function of advancing age and, to an even greater extent, in several human neurodegenerative conditions. The mechanisms responsible for their biogenesis and their subcellular origin(s) remain unclear. We previously demonstrated that the sulfhydryl agent, cysteamine (CSH), promotes the accumulation of CA-like inclusions in cultured rat astroglia. In the present study, we show that subcutaneous administration of CSH to adult rats (150 mg/kg for 6 weeks followed by a 5-week drug-washout period) elicits the accumulation of CA in many cortical and subcortical brain regions. As in the aging human brain and in CSH-treated rat astrocyte cultures, the inclusions are periodic acid-Schiff -positive and are consistently immunostained with antibodies directed against mitochondrial epitopes and ubiquitin. Our findings support our contention that mitochondria are important structural precursors of CA, and that CSH accelerates aging-like processes in rat astroglia both in vitro and in the intact brain.

Aging↗
PubMed1998

Hepatocyte growth factor (HGF/SF) in Alzheimer's disease.

Hepatocyte growth factor (HGF/SF), is a heparin-binding polypeptide which stimulates DNA synthesis in a variety of cell types and also promotes cell migration and morphogenesis. HGF/SF mRNA has been found in a variety of tissues, including brain. In a previous study, we showed that basic fibroblast growth factor (bFGF), another heparin-binding protein is increased in Alzheimer's disease (AD), and appears to be associated with the heparan-sulfate proteoglycans bound to B/A4 amyloid (Biochem. Biophys. Res. Commun. 171 (1990) 690-696). In the present study, we examined the distribution of HGF/SF in 4% paraformaldehyde fixed samples of prefrontal cortex from control and Alzheimer patients, in order to assess the possibility that HGF/SF may be found in association with the pathologic changes which occur in Alzheimer's disease. A specific polyclonal antibody directed against HGF/SF revealed widespread HGF/SF-like immunoreactivity in both the cerebral cortex and white matter. Confocal microscopy confirmed that HGF/SF could be found in both GFAP positive astrocytes and LN3 positive microglia cells, as well as rare scattered cortical neurons. In the AD cases studied, the immunoreactivity was increased within both the astrocytes and microglial cells surrounding individual senile plaques. No staining was seen within the neurofibrillary tangles. Western blot analysis confirmed the normal molecular form of HGF/SF in Alzheimer's disease. Quantitative ELISA assay demonstrated a significant increase in HGF/SF in AD relative to age matched controls. These studies confirm the presence of HGF/SF immunoreactivity within neurons, astrocytes and microglial cells. They also indicate that HGF/SF may be increased within senile plaques as a function of the gliosis and microglial proliferation which occurs in association with these structures in Alzheimer's disease.

Aged↗
PubMed1998

Neural heme oxygenase-1 expression in idiopathic Parkinson's disease.

Heme oxygenase-1 is a cellular stress protein expressed in brain and other tissues in response to oxidative challenge and other noxious stimuli. In the present study, immunohistochemistry was used to assess HO-1 expression in various postmortem human brain specimens derived from PD and control subjects. In the substantia nigra of both PD and control specimens, moderate HO-1 immunoreactivity was consistently observed in neuromelanin-containing (dopaminergic) neurons. Lewy bodies in PD nigra neurons exhibited intense HO-1 immunostaining in their peripheries. In both PD and control specimens, neuronal HO-1 staining was faint or nondetectable in the other brain regions surveyed. The fraction of GFAP-positive astroglia expressing HO-1 in PD substantia nigra (77.1 +/- 12.3) was significantly greater than that observed in the substantia nigra of control subjects (18.7 +/- 7.1; P = 0.0015). In the other regions examined, percentages of GFAP-positive astroglia coexpressing HO-1 were relatively low and did not differ significantly (P > 0.05) between control and PD specimens. Upregulation of HO-1 in the substantia nigra of PD subjects supports the view that the affected tissue is experiencing chronic oxidative stress. In addition, excessive cellular levels of heme-derived free iron and carbon monoxide resulting from HO-1 overactivity may contribute to the pathogenesis of PD.

Aged↗
PubMed1998

Astrocyte mitochondria: a substrate for iron deposition in the aging rat substantia nigra.

Little is currently known concerning the cellular substrates for, and the mechanisms mediating the pathological deposition of, redox-active brain iron in Parkinson's disease. In various subcortical brain regions, populations of astroglia progressively accumulate peroxidase-positive cytoplasmic inclusions derived from effete, iron-laden mitochondria. In the present study, histochemical, ultrastructural, and elemental microanalytical techniques were used to demonstrate the existence of peroxidase-positive astroglia in the substantia nigra of adult rats. At 4 months of age and earlier, few GFAP-positive nigral astroglia contained small, electron-dense cytoplasmic inclusions which exhibited faint endogenous peroxidase activity (diaminobenzidine reaction product) and no detectable iron by microprobe analysis. In contrast, by 14-18 months of age, there was a significant, fourfold increase in numbers of peroxidase-positive astrocyte inclusions in the substantia nigra. The nigral gliosomes in the older animals were heterogeneously electron dense, immunoreactive for ubiquitin and a mitochondrial epitope, and often exhibited X-ray emission peaks for iron. Copper peaks were also detected in a minority of nigral gliosomes. Previous in vitro work indicated that the iron-mediated peroxidase activity in these cells promotes the bioactivation of dopamine and other catechols to neurotoxic free radical intermediates. Thus, mitochondrial sequestration of redox-active iron in aging nigral astroglia may be one factor predisposing the senescent nervous system to parkinsonism and other neurodegenerative disorders.

Aging↗
PubMed1998

Spinobulbar muscular atrophy: polyglutamine-expanded androgen receptor is proteolytically resistant in vitro and processed abnormally in transfected cells.

The neuronotoxicity of genes with expanded CAG repeats is most likely mediated by their respective polyglutamine (Gln)-expanded gene products. Gln- expanded portions of these products may be sufficient, or necessary, for pathogenesis. We tested whether a Gln-expanded human androgen receptor (AR) is structurally altered, so that it allows for the proteolytic generation of a potentially pathogenic portion that may be resistant to further degradation. We found, in vitro , that a Gln-expanded AR is more proteolytically resistant than normal, and that it yields a distinct set of Gln-expanded fragments even after extended proteolysis in the presence of 2 M urea. Furthermore, COS cells transfected with CAG-expanded AR cDNA generate an aberrant, nuclear-associated 75 kDa derivative containing the Gln-expanded tract. They are also twice as likely to die by 24 h apoptotically than those transfected with normal AR cDNA. Our data support the notion that an unconventional derivative of the Gln- expanded AR is a component of the proximate motor neuronopathic agent in spinobulbar muscular atrophy. They also focus attention on two ways in which neuronotoxic derivatives may originate from various Gln-expanded proteins: (i) generation of an unusual derivative that is pathogenic de novo ; and (ii) the toxic accumulation of a normal derivative because of an inability to dispose of it.

Animals↗
PubMed1998

Mercuric chloride induces a stress response in cultured astrocytes characterized by mitochondrial uptake of iron.

Mercury exerts a variety of toxic effects on both neurons and glia. Mercury induces aberrations in microtubules, ion channels and mitochondria presumably by binding to sulfhydryl groups. Indirect evidence further suggests that mercury targeted to mitochondria may induce iron-catalyzed oxygen radical production. We have previously shown that the mitochondria of astrocytes subjected to oxidative stress accumulate redox active transition metals that may catalyze the formation of cytotoxic oxygen free radicals. In the present study we have investigated the effect of mercuric chloride on astrocytes in monolayer culture in order to determine whether mercury accumulates in astrocytic mitochondria and whether mercury exposure triggers a stress response-associated uptake of iron. Our results indicate that mercuric chloride exposure initiates the constellation of changes in mitochondrial structure that typifies the response of these cells to oxidative stress. Energy dispersive Xray microspectroscopy demonstrates that these altered mitochondria concentrate both mercury and iron. Concurrent with these changes, mercuric chloride treatment activates transcription of the heme oxygenase-1 (HO-1) gene in a dose dependent manner, further indicating an oxidative stress response. Thus, mercury-induced stress may transform innocuous astrocytes into potentially lethal sources of cytotoxic oxygen free radicals.

Animals↗
PubMed1997

Long-term effects of cysteamine on cognitive and locomotor behavior in rats: relationship to hippocampal glial pathology and somatostatin levels.

Peroxidase-positive astrocytic inclusions, derived from effete, iron-laden mitochondria, accumulate in the rat hippocampus, striatum and other subcortical brain regions as a function of advancing age. The sulfhydryl agent, cysteamine (CSH), accelerates the appearance of this senescent glial phenotype both in primary astrocyte cultures and in the aging subcortical brain in situ. Earlier experiments have shown that short-term administration of CSH results in reversible depletion of brain somatostatin (SS) levels, cognitive deficits and decreases in locomotor activity. In the present study, we tested spatial learning/memory and motor functioning in rats at 4-5 weeks following cessation of chronic (6 week) CSH treatment to determine whether behavioral deficits may be associated with gliopathic changes within the dorsal hippocampus distinct from the behavioral abnormalities accruing to the immediate effects of the drug. CSH-treated rats displayed significantly impaired performance in the Morris water maze 4-5 weeks following termination of prolonged CSH treatment. In contrast, locomotor activity was not affected in this experimental paradigm. CSH-treated animals exhibited significantly higher numbers of peroxidase-positive astrocyte granules as well as total numbers of GFAP-positive astrocytes in the CA1 sector of the dorsal hippocampus relative to saline-treated controls. In the hilus of the dentate gyrus, numbers of both peroxidase-positive glial inclusions and astrocytes were unaffected by CSH exposure. At 5 weeks following cessation of CSH treatment, SS levels in the hippocampus and hypothalamus (but not cerebral cortex) were elevated relative to those of saline-treated controls. Our results indicate that chronic CSH exposure induces senescence-like changes in CA1 astrocytes which are associated with deficits in cognitive, but not locomotor, behavior and elevated levels of hippocampal and hypothalamic SS. Pathological glial-neuronal interactions within the hippocampus and other subcortical brain regions may play an important role in the cognitive decline observed during normal senescence and in aging-related neurodegenerative disorders.

Animals↗
PubMed1997

A cellular stress model for the differential expression of glial lysosomal cathepsins in the aging nervous system.

Activation of the endosomal-lysosomal system and altered expression of various lysosomal hydrolases have been implicated in several senescence-dependent neurodegenerative disorders and occurs, to a lesser extent, in the course of normal brain aging. The progressive accumulation of autofluorescent, peroxidase-positive astrocytic granules represents a highly consistent biomarker of aging in the vertebrate CNS. The sulfhydryl agent cysteamine greatly accelerates the accumulation of these glial inclusions in situ and in primary brain cell cultures. We previously determined that these glial inclusions are derived from abnormal mitochondria which undergo fusion with lysosomal elements in a complex autophagic process. In the present study, we demonstrate that cysteamine suppresses cathepsin B mRNA levels and immunoreactive protein in cultured astroglia, whereas cathepsin D mRNA and protein levels are significantly augmented by CSH exposure in these cells. Moreover, cathepsin D (but not cathepsin B) exhibits robust colocalization to the red autofluorescent inclusions. Concordant with our in vitro observations, cathepsin B immunoreactivity is prominent in the hypothalamic ventromedial nucleus which accumulates few autofluorescent glial inclusions during aging and is relatively inapparent in the heavily granulated hypothalamic arcuate nucleus. Conversely, cathepsin D is prominent in the aging arcuate nucleus where it colocalizes to the autofluorescent inclusions and exhibits scant immunoreactivity in the adjacent ventromedial nuclear complex. In senescent astroglia, oxidative stress may down-regulate the cathepsin B gene as part of a concerted cellular stress (heat shock) response. Glial cathepsin D, on the other hand, resists stress-related inhibition and may play an important role in disposing of oxidatively modified mitochondria in the aging and degenerating nervous system.

Aging↗
PubMed1996

Mapping of the basal forebrain cholinergic system of the dog: a choline acetyltransferase immunohistochemical study.

In an effort to produce a canine model of basal forebrain ischemia with memory deficits, we have shown that dogs possess a medial striate artery that perfuses basal forebrain territory, homologous to the human recurrent artery of Heubner. In the present study, we set out to delineate the precise topography of the cholinergic neurons in the canine forebrain, a neuronal system implicated in cognitive and memory functions. Floating coronal sections, derived from the head of the caudate nucleus to the rostral border of the hippocampus, were stained for choline acetyltransferase using a monoclonal antibody. Representative sections from one dog brain were drawn. These outlines were used for measurement of cell density, cell size, number of processes, and cell roundness. Choline acetyltransferase-positive neurons constituted four major subdivisions within the basal forebrain. A relatively dense population of cholinergic neurons was present in the medial septal nucleus (Ch1). A continuum of densely packed cells was also delineated within the vertical (Ch2) and horizontal (Ch3) nuclei of the diagonal band of Broca. A fourth group of heterogeneously packed cholinergic neurons represented the nucleus basalis magnocellularis (Ch4). Except for the caudal component of the Ch4 population, the forebrain cholinergic corticopetal system was located within the perfusion territory of the medial striate arteries. The Ch4 cell group in dogs is better defined than that of rodents but is not as sharply demarcated as in human and nonhuman primates. Our findings indicate that the dog may serve as an excellent model for assessing neurological and memory deficits, which, in humans, results from hypoperfusion of the recurrent artery of Heubner.

Analysis of Variance↗
PubMed1996

Headache and scalp edema in sickle cell disease.

BACKGROUND: Major neurological complications of sickle cell disease include cerebral infarction and intracranial hemorrhages. METHODS: We describe the case of a 25-year-old man with sickle cell disease who developed a severe headache of acute onset, located at the vertex. There was associated pitting edema of the scalp. RESULTS: Technetium and gallium bone imaging showed focal decreased uptake of the tracers, consistent with a recent fronto-parietal skull infarction. Management included intravenous hydration and analgesic medication. CONCLUSIONS: In addition to the more common intracranail vaso-occlusive complications, skull infarction should be considered as a cause of newonset headache in patients with sickle cell disease, especially if scalp edema is present.

Adult↗
PubMed1996

Expression of the somatostatin gene in human astrocytoma cell lines.

Somatostatin (somatotropin release-inhibiting hormone; SRIH) has been demonstrated in neurons of the central nervous system (CNS) as well as in endocrine cells of the pancreas and gastrointestinal tract and can suppress various immune functions including lymphocyte proliferation, immunoglobulin synthesis, and cytokine production. Since astrocytes possess antigen-presenting activity and can secrete a wide array of immunoregulatory and inflammatory cytokines, we studied SRIH gene expression in both astrocyte cell lines and mitogen-stimulated peripheral blood mononuclear leukocytes from healthy donors. We now report by means of a complementary DNA-based reverse transcription PCR that differential levels of SRIH mRNA were expressed in 9 of 11 human astrocytoma cell lines tested but were undetectable in activated peripheral blood mononuclear leukocytes as well as in a variety of human lymphocyte and monocyte cell lines. The synthesis and secretion of SRIH protein by astrocytoma cells that expressed SRIH transcripts were confirmed by specific radioimmunoassay of cell culture fluids. These findings support the notion that SRIH gene expression occurs in human astrocytoma cells but not in mature lymphoid cells of the immune system.

Astrocytoma↗
PubMed1995

Phenotypic and cell cycle properties of human oligodendrocytes in vitro.

The remyelination, albeit limited, which occurs at the lesion sites in the central nervous in multiple sclerosis has been attributed to both myelin production by previously myelinating cells and to precursor cells which mature into myelin-producing cells. Oligodendrocyte (OL) number may be increased at the periphery of the lesions. In this study, we assessed the state of maturation and cell cycle-dependent properties of OLs derived from surgically resected adult human cerebral cortex specimens. In 6-day-old OL cultures, a small proportion of cells (14.1 +/- 3.5%: range 4-24%) expressed an immature phenotype, defined as A007+:myelin basic protein (MBP)-negative. Using lack of statin expression as an index of cells exiting the G0 phase of the cell cycle, we observed that 4.6 +/- 1.6% of A007+ cells, but only rare MBP+ cells (0.4 +/- 1.8%) were non-reactive with the anti-statin antibody, S44. The proportion of non-statin-reactive cells was not affected by treatment with basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF) or insulin-like growth factor (IGF). The oligodendrocytes did not incorporate BrdU during a 48-h pulse and did not immunoreact with Ki-67 antibody. In 4-week-old cultures, we found that all A007+ cells were also MBP+ and that 99.5 +/- 0.7% were statin-positive. Exposing 4-week-old OLs to conditions of serum deprivation or to 1,000 units/ml of recombinant human TNF-beta for 4 days induced nuclear fragmentation in a high proportion (> 70%) of cells, as measured by a TUNEL technique; in these cultures, a similarly high proportion of cells were non-immunoreactive with anti-statin antibody. Our results suggest that a small number of phenotypic 'pre-oligodendrocytes' can be derived from the adult human CNS and that a proportion of these cells have exited the G0 phase of the cell cycle. Attempt at cell cycling, however, could reflect abortive mitosis and activation of programmed cell death.

Cell Cycle↗
PubMed1995

Expression of heme oxygenase-1 in the senescent and Alzheimer-diseased brain.

Heme oxygenase-1 is a cellular stress protein expressed in brain and other tissues in response to oxidative challenge and other noxious stimuli. Using immunohistochemistry and immunofluorescent labeling in conjunction with laser scanning confocal microscopy, we observed intense immunoreactivity of heme oxygenase-1 in neurons of the hippocampus and temporal cortex of Alzheimer-diseased (AD) brain relative to age-matched control specimens. Furthermore, we demonstrated consistent colocalization of heme oxygenase-1 to glial fibrillary acidic protein-positive astrocytes, neurofibrillary tangles, and senile plaques in the AD specimens. In AD hippocampus, approximately 86% of glial fibrillary acidic protein-positive astrocytes expressed heme oxygenase-1, whereas only 6.8% of hippocampal astrocytes in normal senescent control specimens were immunopositive for heme oxygenase-1 (p < 0.0001). In regions other than the hippocampus and neocortex, such as the substantia nigra, the proportion of astrocytes expressing heme oxygenase-1 in the experimental group (12.8%) was not significantly different from that in the controls (6.4%, p > 0.05). Robust 32-kd bands corresponding to heme oxygenase-1 were observed by Western blotting of protein extracts derived from AD temporal cortex and hippocampus after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Heme oxygenase-1 bands were very faint or absent in protein extracts prepared from control specimens. These results indicate that heme oxygenase-1 is significantly overexpressed in neurons and astrocytes of AD hippocampus and cerebral cortex relative to control brains. Upregulation of heme oxygenase-1 in AD brain supports the contention that the affected tissues are experiencing chronic oxidative stress. In addition, the excessive generation of carbon monoxide, a metabolite of heme degradation, may participate in the pathogenesis of AD.

Aged↗
PubMed1995

Mitochondrial constituents of corpora amylacea and autofluorescent astrocytic inclusions in senescent human brain.

Corpora amylacea (CA) are cytoplasmic inclusions that accumulate in human brain in the course of normal aging, and to an even greater extent, in Alzheimer's disease and other neurodegenerative conditions. In senescent and Alzheimer-diseased human brains, astrocytes in limbic and periventricular regions exhibit red autofluorescent inclusions, homologous to Gomori-positive astrocyte granules previously described in the brains of aging rodents and other vertebrates. We have shown that Gomori inclusions in situ and in culture are derived from autophagocytosed mitochondria exhibiting iron-mediated peroxidase activity. In the human brain, the autofluorescent inclusions share many properties with CA. Both types of inclusion progressively accumulate in periventricular regions with advancing age, are largely astrocytic in origin, and contain various heat shock proteins and ubiquitin. Using histochemistry in conjunction with cofocal microscopy, we demonstrated that both CA and the red autofluorescent granules exhibit non-enzymatic peroxidase activity and an affinity for CAH and PAS. The only major divergent histochemical feature between the Gomori-positive astrocyte granules and CA is the presence of orange-red autofluorescence in the former and the absence of endogenous fluorescence in the latter. On the basis of numerous shared topographic and histochemical features, we hypothesized that CA are largely derived from autofluorescent (Gomori-positive) astrocyte granules which reside in periventricular regions of the senescent CNS. Immunofluorescent labeling and laser scanning confocal microscopy demonstrated consistent colocalization of the mitochondrial proteins, sulfite oxidase, and heat shock protein 60, to both CA and the autofluorescent astroglial inclusions. In addition, both CA and the autofluorescent astrocyte granules exhibit staining for DNA which colocalizes to mitochondrial antigens and therefore likely represents mitochondrial nucleic acid in dual-labeled preparations. These observations suggest that a) Gomori-positive astrocyte granules in human brain are homologous to those described in rodents, b) Gomori-positive granules may be structural precursors of CA in senescent human brain, and c) in the aging human brain, degenerate mitochondria within periventricular astrocytes give rise to autofluorescent cytoplasmic granules and corpora amylacea.

Aging↗
PubMed1995

Iron-mediated bioactivation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in glial cultures.

Primary cultures of mouse astrocytes were treated with both the monoamine oxidase (MAO) A inhibitor, clorgyline, and the MAO B inhibitor, deprenyl, prior to the addition of the neurotoxicant 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Production of the 1-methyl-4-phenylpyridinium (MPP+) toxic metabolite was reduced to 11%, but not completely blocked, by MAO inhibition. This residual MPP+ production appeared to be iron-dependent since it was decreased (30 to 50%) by iron chelators, i.e., deferoxamine or phenanthroline, and was enhanced (by approximately 40%) in the presence of ADP-Fe3+. ADP-Fe3+ also enhanced the oxidation of MPTP to MPP+ which occurs in medium without cells. MPP+ formation, however, was significantly slower in plain culture medium than in astrocyte incubations pretreated with MAO inhibitors, suggesting the involvement of cells in these iron-mediated reactions. The data indicate that oxidation via MAO is the primary but not the only pathway of MPTP bioactivation and that transition metals may contribute to the generation of the toxic MPP+ metabolite in biological systems.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗