bluuebunny/crossref_metadata_2025_split huggingface dataset:
Astroglial alterations in rat hippocampus during chronic lead exposure
Authors: Selvín‐Testa Asia , Lopez‐Costa J. J. , Nessi De Avin̈n A. C. , Pecci Saavedra J. 
Published: January 2005

AbstractThe present study was performed in order to follow the response of astroglial cells in the rat hippocampus to chronic low‐level lead exposure. The experiments combined immunohistochemistry using anti‐glial fibrillary acidic protein (GFAP) antibody and conventional transmission electron microscopy (EM). Chronic administration with drinking water [1 g% w/v (subclinical dose) of lead acetate dissolved in distilled water] was started through the mother's milk when pups were 7 days old. Following weaning, experimental offspring were treated for 3 months with the same concentration of adulterated water. The group of intoxicated animals and their controls were sacrificed by perfusion‐fixation at 30, 60, and 90 days of exposure. After 60 days of lead treatment, staining of GFAP‐positive cells demonstrated an astroglial transformation from the quiescent to the reactive state, characterized by an increase in GFAP. In control rats no changes in GFAP immunostaining were observed. The intensity of the astroglial response was enhanced after 90 days of lead intoxication, showing an increment of GFAP immunoreactivity. Quantification of these changes was made by computerized image analysis, confirming that the sectional areas of the astroglia in lead‐exposed animals were larger than those in controls. These results are consistent with the ultrastructural alterations. Simultaneously with the increment in gliofilaments, intranuclear inclusions were seen in some astrocytes. The mechanisms by which lead affects astrocytes are unknown. Probably the astroglial changes induced by lead intoxication produce microenvironmental modifications that may disturb the neuronal function.
Heterogeneous astroglial response in the rat spinal cord to long‐term portacaval shunt: An immunohistochemical study
Authors: Bodega G. , Suárez I. , Arilla E. , Rubio M. , Fernández B. 
Published: January 2005

AbstractGlial fibrillary acidic protein (GFAP) immunoreactivity has been used to study the astroglial response in the rat spinal cord to long‐term portacaval shunt (PCS). The astroglial response in PCS rats is heterogeneous. In general, astrocytes show a loss of GFAP immunoreactivity, as well as shrinking and pyknosis in their nuclei; however, while GFAP reactivity was unchanged in the periependymal region, it was strongly increased in the dorsolateral region of the spinal cord (lateral spinal nucleus, dorsal root entry zone, and the most dorsal region of the dorsal horn). Three possibilities are postulated to explain how astrocytes, in the periependymal and dorsolateral regions, can support the effects of PCS: (a) astrocytes related to glutamatergic pathways ought to possess a more efficient ammonia uptake and detoxification system, (b) long‐term PCS can activate nociceptive pathways (substancePergic fibers), and (c) astrocytes located in periependymal and dorsolateral regions can be exposed to lower concentrations of ammonia because of its diffusion into the cerebro‐spinal fluid close to these regions.
Virulent and attenuated canine distemper virus infects multiple dog brain cell types in vitro
Authors: Pearce‐Kelling Susan , Mitchell William J. , Summers Brian A. , Appel Max J. G. 
Published: January 2005

AbstractCanine Distemper Virus (CDV) produces an encephalitis in dogs that varies with viral strain. We have studied the cell tropisms of two virulent strains (CDV‐SH and CDV A75–17) and an attenuated strain, Rockborn (CDV‐RO), in cultured canine brain cells. Infected cell types were identified by double immunofluorescent labeling of specific cell markers and viral antigens. All viral strains studied produced infection in astrocytes, fibroblasts, and macrophages. Neurons were not infected by CDV A75–17 but were rapidly infected by CDV‐SH and CDV‐RO. Multipolar oligodendrocytes were very rarely infected by any of the virus strains. In contrast, a morphologically distinct subset of bipolar oligodendrocytes were commonly infected by CDV‐SH and CDV‐RO. The kinetics of infection in the astrocytes, oligodendrocytes, neurons, and macrophages varied between strains. Both CDV‐SH and CDV‐RO rapidly infected bipolar oligodendrocytes, astrocytes, neurons, and macrophages by 14 days post infection while infection by CDV A75–17 was delayed until after 28–35 days post infection. The differences in the growth kinetics and cell tropisms for some brain cells, exhibited by the three viral strains examined in this in vitro study, may relate to the different CNS symptoms that these strains produce in vivo.
Modulation of intracellular Ca++ in cultured astrocytes by influx through voltage‐activated Ca++ channels
Authors: Macvicar Brain A. , Hochman Daryl , Delay Michael J. , Weiss Samuel 
Published: January 2005

AbstractFura‐2 and indo‐1 fluorescence measurements were used to examine intracellular Ca++ concentration ([Ca++]i) and its modulation by voltage‐activated influx in murine cortical astrocytes in primary cell culture. Extracellular K+ was increased from 5 to 50 mM to depolarize cells to determine if Ca++ influx through voltage activated Ca++ channels could alter [Ca++]i. In confluent 4 to 6 weeks in vitro astrocyte cultures 50 mM K+ increased [Ca++]i 3‐4‐fold (from 150 nM up to 550 nM); this increase was blocked by nifedipine and enhanced by BayK 8644 indicating that influx was through L‐type channels. However, in 1 to 2 weeks in vitro astrocyte cultures, high K+ reduced [Ca++]i. L‐type channels were apparently present in these cells because high K+ in combination with BayK 8644 increased [Ca++]i. Following pretreatment of 1 to 2 weeks in vitro astrocytes with dibutyryl cAMP (dbcAMP) high K+ increased [Ca++]i in the absence of BayK 8644 indicating enhanced activity of Ca++ channels in agreement with previous voltage‐clamp studies. Ca++ influx through voltage‐activated channels in cultured cortical astrocytes can substantially increase [Ca++]i and these channels can be dynamically modulated by dihydropyridines. Immature astrocytes may express ‘silent’ or inactive Ca++ channels or have a much lower number of channels.
In vitro myelination of regenerating adult rat retinal ganglion cell axons by schwann cells
Authors: Bähr M. , Hopkins J. M. , Bunge R. P. 
Published: January 2005

AbstractSchwann cell cultures provide a highly favorable substrate for retinal ganglion cell (RGC) survival and axon growth in vitro (Bähr and Bunge, Exp Neurol 106:27, 1989; Hopkins and Bunge, Glia 4:46, 1991). In this report we have extended former studies to obtain axon regeneration, long‐term survival, and myelination of adult rat RGC axons in co‐cultures of retinal explants with purified Schwann cells. By using modified co‐culture conditions, we observed myelination of regenerating adult RGC axons by Schwann cells after 3–4 weeks in vitro. Myelination was associated with a one‐to‐one Schwann cell‐axon relationship, characteristic of the formation of peripheral myelin. Under culture conditions that supported myelination, long‐term survival (more than 12 weeks) of a small population of RGCs was observed. These findings highlight the remarkable ability of Schwann cells to support long‐term survival of adult rat RGCs in the absence of either central nervous system (CNS) target tissue or other peripheral nervous system (PNS) components. This tissue culture system may serve as a model for the systematic study of the molecular mechanisms which are involved in axon regeneration and myelination of adult CNS neurons.
Orientation of the myelin proteolipid protein C‐terminus in oligodendroglial membranes
Authors: Konola Jukka T. , Yamamura Takashi , Tyler Betty , Lees Marjorie B. 
Published: January 2005

AbstractThe topology of the integral membrane proteolipid protein (PLP) has important structural and functional implications for central nervous system myelin. To determine the orientation of the carboxyl‐terminal portion of PLP, cultured mouse oligodendrocytes were probed with polyclonal antibodies raised against a synthetic terminal peptide corresponding to PLP residues 264–276 and with ten separate monoclonal antibodies that react with this region. Cells were examined by double‐label indirect immunofluorescence for the presence of the PLP C‐terminus and either oligodendrocyte‐specific surface or intracellular antigens. To detect surface antigens, both living and paraformaldehyde‐fixed cells were incubated with primary antibodies and then stained with fluorochrome‐conjugated second antibodies. Antigens located within the cytoplasmic space were identified after fixation and permeabilization of cells. Live‐labeled oligodendrocytes were stained brightly for myelin‐oligodendrocyte glycoprotein, galactocerebroside, and other surface markers but did not stain for the PLP C‐terminus or the intracellular proteins myelin basic protein and beta‐tubulin. Fixation alone was sufficient for partial permeabilization of oligodendrocytes to antibodies and resulted in limited staining of the PLP C‐terminus and intracellular proteins. The permeabilized oligodendrocytes stained intensely for the PLP C‐terminus, myelin basic protein, and betatubulin. Finally, trypsinization of living oligodendrocytes eliminated surface myelin‐oligodendrocyte glycoprotein staining but did not change the immunostaining properties of the PLP C‐terminus. These results provide evidence that the carboxyl‐terminus of PLP is located at the cytoplasmic face of oligodendroglial membranes.
The abundance of Aplysia gliagrana depends on Ca2+ and/or Na+ concentrations in sea water
Authors: Keicher Erick , Maggio Katia , Hernandez‐Nicaise Mari‐Luz , Nicaise Ghislain 
Published: January 2005

AbstractThe glial cells surrounding the identified giant nerve cell bodies R2 or LP1 of Aplysia punctata were studied by quantitative electron microscopy. They contain specific, electron‐dense but non‐osmiophilic membrane‐bound granules, approximately 0.3 μm in diameter, called gliagrana. Similar glial granules are more often found in marine than in freshwater molluscs, possibly because they represent a calcium store used to compensate excess Na+ in the extracellular milieu of marine species and to regulate perineuronal calcium concentration. In agreement with this hypothesis, the abundance of gliagrana (=number of glial granules per μm2) is found to be higher in animals adapted to low Ca2+ artificial sea water than in animals kept in high Ca2+ (or low Na+) conditions. This finding is not observed after 1 week but after 2 weeks of adaptation.
Zinc toxicity and induction of the 72 kD heat shock protein in primary astrocyte culture
Authors: Swanson Raymond A. , Sharp Frank R. 
Published: January 2005

AbstractZinc is a potent inducer of the 72 kD heat shock protein (HSP72). In brain, pathological conditions such as ischemia and seizures increase extracellular zinc. The present study examines the effect of zinc on HSP72 expression in rat primary cortical astrocyte culture. Astrocytes were grown to confluence and exposed to zinc chloride in CO2‐equilibrated Earle's buffered salt solution. Expression of HSP72 was examined using immunocytochemistry. HSP72 was induced with zinc concentrations of 5 to 100 μM after 4 h exposures, or 200 to 300 μM after 15 min exposures. At the lower concentrations expression occurred in small clusters of contiguous cells. At concentrations high enough to cause cell death, HSP72‐positive astrocytes formed a continuous margin around patches of dead cells. These patterns of HSP72 expression are similar to the patterns seen after cerebral ischemia in vivo. Exposure to zinc at 100 μM for 4 h or 400 μM for 15 min caused greater than 90% cell death. Increases in extracellular zinc may contribute to HSP72 induction and astrocyte death under ischemia and other pathological conditions in brain. © 1992 Wiley‐Liss, Inc.
Comparative biochemical, morphological, and immunocytochemical studies between C‐6 glial cells of early and late passages and advanced passages of glial cells derived from aged mouse cerebral hemispheres
Authors: Lee Kendall , Kentroti Susan , Billie Holly , Bruce Clifford , Vernadakis Antonia 
Published: January 2005

AbstractWe have used C6 glial cells (2B clone), early and late passage, as well as advanced passages (8–17) of glial cells derived from aged (18‐month‐old) mouse cerebral hemispheres (MACH), as model systems for studying glial properties. In this study passages 20–24 were considered “early” and passages 73–90 were considered “late.” Activities of glutamine synthetase (GS) and cyclic nucleotide phosphohydrolase (CNP) were used as biochemical markers for astrocytes and oligodendrocytes, respectively. Glial phenotypes were identified immunocytochemically using double staining for glial fibrillary acidic protein (GFAP) and A2B5 antigen (type 1 and type 2 astrocytes) or galactocerebroside (GalC) and A2B5 antigen (oligodendrocytes); cells positive for A2B5 and negative for both GFAP and GalC were considered to be precursor cells. Cultures were grown either in DMEM supplemented with 10% fetal bovine serum or in serum‐free chemically defined medium (CDM) supplemented with insulin and transferrin. We report that early‐passage C6 glial cells continue to be bipotential cells and when grown in the absence of serum express high GS and CNP activities correlating with the high number of GFAP‐ and GalC‐positive cells, respectively. Late‐passage cells continued to be committed to the type 2 astrocytic phenotype regardless of media composition (± serum). MACH cultures consist of protoplasmic type 1 astrocytes, differentiated type 2 astrocytes, and oligodendrocytes as well as glial progenitor cells. When these cultures were grown in CDM + transferrin, both GS and CNP activities increased, suggesting that transferrin has provided the signal for progenitor cells present in these cultures derived from aged brain to differentiate into type 2 astrocytes and oligodendrocytes. © 1992 Wiley‐Liss, Inc.
Differential proliferative response of human and mouse astrocytes to gamma‐interferon
Authors: Yong Voon Wee , Tejada‐Berges Trevor , Goodyer Cynthia G. , Antel Jack P. , Yong Flons P. 
Published: January 2005

AbstractWe have previously shown that gamma‐interferon promoted the proliferation of adult human astrocytes isolated from brain biopsy specimens. In contrast, in the present study, astrocytes derived from neonatal mouse brains and treated with recombinant murine gamma‐interferon responded by a decreas (average of 50% at 100 U/ml) in proliferation. The basal rate of proliferation as assessed by bromodeoxyuridine incorporation was markedly increased in neonatal mouse astrocytes when compared to the adult human cells, suggesting that age, and the corresponding metabolic activity of cells, could be important determinants in the mitogenic response of astrocytes to cytokines. However, subsequent examinations of fetal human and adult mouse astrocytes, with comparable basal rate of proliferation to neonatal mouse and adult human cells respectively, showed gamma‐interferon to promote DNA synthesis in fetal human astrocytes while inhibiting that of adult mouse astrocytes. The results suggest species differences in the proliferative response of human and mouse astrocytes to the cytokine gamma‐interferon. © 1992 Wiley‐Liss, Inc.
Clonal segregation of oligodendrocytes and astrocytes during in vitro differentiation of glial progenitor cells
Authors: Lubetzki Catherine , Goujet‐Zalc Cecile , Demerens Corinne , Danos Olivier , Zalc Bernard 
Published: January 2005

AbstractTo study the clonal lineage of the glial progenitor population, isolated from newborn rat brain (Lubetzki et al. J Neurochem 56:671, 1991), we combined somatic transgenesis using a retroviral vector encoding a modified bacterial β‐galactosidase with nuclear localization, and triple immunofluorescence labeling with A2B5, anti‐galactosylceramide, and anti‐glial acidic fibrillary protein antibodies. This allowed clonal analysis of the postnatal glial lineage with precise phenotypic identification of each cell within the lacZ‐positive clones. When infected cells were cultivated under constant conditions, in the presence of either 1% or 10% fetal calf serum (FCS)‐containing medium, all the 250 lacZ‐positive clusters examined were homogeneous, i.e., either oligodendroglial or astroglial. Mixed astrocyte—oligodendroglial clones were observed when cells cultivated in the presence of 1% FCS were switched to a 10% FCS‐containing medium, confirming the bipotentiality of glial progenitor cells (Temple and Raff Nature 313:223, 1985). However, even under the switch culture conditions, segregation into homogeneous clones of either oligodendrocytes or astrocytes still predominated, and the percentage of mixed clones dropped from 25 to 8 or to 3, when the switch took place at 8, 16, or 22 days in vitro, respectively. Two additional observations lead us to suggest that microenvironmental factors are responsible for the clonal segregation of glial progenitor cells: 1) the uneven distribution of oligodendrocyte and astrocyte clusters, the latter being seen mostly on the edge of the coverslips; and 2) the presence, in the vicinity of an homogeneous lacZ‐positive clone, of some lacZ‐negative cells expressing the same phenotype. © 1992 Wiley‐Liss, Inc.
The origin and nature of ramified and amoeboid microglia: A historical review and current concepts
Authors: Ling Eng‐Ang , Wong Wai‐Chow 
Published: January 2005

AbstractThe origin of ramified microglia has been a longstanding controversial issue, with 4 major schools of thought, which state that they are derived (1) from invasion of mesodermal pial elements, (2) from neuroectodermal matrix cells together with the macroglia, (3) from pericytes, and (4) from invasion of monocytes in early development. This paper is in support of the last‐mentioned hypothesis. It is known that ramified microglial cells do not divide under normal circumstances, and since our studies in the corpus callosum have shown that these cells do not appear until the fifth postnatal day, it is reasoned that they must be derived from some preexisting mitotically active cells. The putative precursor is the preponderant amoeboid microglia in the same region. Our experimental studies with the carbon labelling technique have demonstrated for the first time that blood monocytes invade into the early postnatal brain to become amoeboid microglia, which then differentiate into ramified microglia. Just like other tissue macrophages, the monocyte‐derived amoeboid microglia exhibit features indicative of phagocytic activities. These include the content of hydrolytic enzymes, uptake of carbon, and a characteristic surface morphology, as seen by scanning electron microscopy. The transformation of amoeboid microglia into ramified microglia, which occurs between the second and third postnatal week, is considered to be a regressive phenomenon, as shown by the diminution of their content of hydrolytic enzymes and the downregulation of membrane antigen. Apart from their primary role as active phagocytes, their involvement in Alzheimer's disease (AD) is evidenced recently by the fact that the cells are specifically marked by antibodies present in the cerebrospinal fluid of AD patients. In conclusion, ramified microglial cells are derived from monocytes, but through an intermediate amoeboid microglia stage as active macrophages in the perinatal period.
Bone marrow derived elements and resident microglia in brain inflammation
Authors: Lassmann Hans , Schmied Mascha , Vass Karl , Hickey William F. 
Published: January 2005

AbstractInfection of the central nervous (CNS) system by the human immunodeficiency virus (HIV) depends on the migration of infected hematogenous cells into the brain. We thus used quantitative light and electron microscopic immunocytochemistry to study the homing and turnover of bone marrow derived cells in the CNS in radiation bone marrow chimeras under normal conditions and in experimental autoimmune encephalomyelitis (EAE) as an experimental model of brain inflammation. Our studies suggest the following conclusions. First, the central nervous system is continuously patrolled by a small number of T‐lymphocytes and monocytes. Meningeal and perivascular monocytes are slowly replaced by hematogenous cells under normal conditions, and this turnover is accelerated in the course of inflammation. In contrast, resident microglia represent a very stable cell pool, which in adult animals is only exceptionally replaced by hematogenous cells, even after recovery from severe brain inflammation. Second, although in bone‐marrow‐chimeric animals resident microglia, astrocytes, and ependymal cells are not able to present antigen to Lewis T‐lymphocytes, the inflammatory reaction in EAE is qualitatively and quantitatively similar in these animals compared to fully histocompatible Lewis rats. Finally, resident microglia express the macrophage activation antigen ED1. Thus, microglia cells appear to function as effector cells in EAE lesions.
Characterization of microglia and macrophages in the central nervous system of rats: Definition of the differential expression of molecules using standard and novel monoclonal antibodies in normal CNS and in four models of parenchymal reaction
Authors: Flaris Nicolaos A. , Densmore Tamara L. , Molleston Michael C. , Hickey William F. 
Published: January 2005

AbstractThis report describes the development of a new panel of monoclonal antibodies produced following immunization of mice with cultured rat microglial cells. Using these new reagents and previously defined antibodies that bind to microglia or macrophages, the responses of parenchymal microglia, perivascular “microglial” cells, and infiltrating macrophage/monocytes were examined in 4 divergent models of central nervous system reaction. These were brain abscess, experimental allergic encephalomyelitis, Wallerian degeneration, and stab wound. No single new anitbody was specific only for microglia; all antibodies positively staining microglial cells also labeled various subsets of macrophage/monocytic cells in normal tissues of the immune system. Moreover, the results indicate that microglia are capable of different levels and a variety of types of response, as defined by the molecules they elaborate. These findings suggest that these CNS resident cells belong to the extended monocyte/macrophage/dendritic cell family and that they do not respond in a stereotypic manner to all forms of CNS insult.