bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymorphonuclear leukocyte infiltration into cerebral focal ischemic tissue: Myeloperoxidase activity assay and histologic verification
Authors: Barone Frank C. , Hillegass L. M. , Price W. J. , White R. F. , Lee E. V. , Feuerstein G. Z. , Sarau H. M. , Clark R. K. , Griswold D. E. 
Published: January 2005

AbstractTwo different techniques were utilized to identify the infiltration of polymorphonuclear leukocytes (PMN) into cerebral tissue following focal ischemia: histologic analysis and a modified myeloperoxidase (MPO) activity assay. Twenty‐four hours after producing permanent cortical ischemia by occluding and severing the middle cerebral artery of male spontaneously hypertensive rats, contralateral hemiparalysis and sensory‐motor deficits were observed due to cerebral infarction of the frontal and parietal cortex. In hematoxylin‐and‐eosin‐stained histologic sections, PMN, predominantly neutrophils, were identified at various stages of diapedesis from deep cerebral and meningeal vessels at the periphery of the infarct, into brain parenchyma. When MPO activity in normal brain tissue was studied initially, it could not be demonstrated in normal tissues extracted from non‐washed homogenates. However, if tissue was homogenized in phosphate buffer (i.e., washed), MPO activity was expressed upon extraction. Utilizing this modified assay, MPO activity was significantly increased only in the infarcted cortex compared to other normal areas of the brain. This was observed in non‐perfused animals and after perfusion with isotonic saline to remove blood constituents from the vasculature prior to brain removal. The increased PMN infiltration and MPO activity were not observed in forebrain tissue of sham‐operated control rats. Also, MPO activity was not increased in the ischemic cortex of MCAO rats perfused immediately after middle cerebral artery occlusion, indicating that blood was not trapped in the ischemic area. By using a leukocyte histochemical staining assay, activity of peroxidases was identified within vascular‐adhering/ infiltrating PMN in the infarcted cortex 24 hr after focal ischemia. An evaluation of several blood components indicated that increased MPO activity was selective for PMN. The observed increase of approximately 0.3 U MPO/g wet weight ischemic tissue vs. nonischemic cerebral tissues probably reflects the increased vascular adherance/infiltration of approximately 600,000 PMN/g wet weight infarcted cortex 24 hr after focal ischemia. This combined biochemical and histological study strongly suggests that PMN adhere within blood vessels and infiltrate into brain tissue injured by focal ischemia and that the associated inflammatory response might contribute to delayed progressive tissue damage in focal stroke. This modified MPO assay is a useful, quantitative index of PMN that can be utilized to elucidate the potential deleterious consequences of neutrophils infiltrating into the central nervous system after cerebral ischemia, trauma, or other pro‐inflammatory stimuli.
Oligodendrocytes and myelin sheaths in normal, quaking and shiverer brains are enriched in iron
Authors: Levine S. M. 
Published: January 2005

AbstractEarly studies employing iron histochemical techniques found a spatially restricted distribution of oli‐godendrocytes and myelin enriched in iron. In particular, Oligodendrocytes and myelin positively stained for iron were found in sparsely myelinated brain regions but not in densely myelinated tracts. Subsequent studies modified the iron histochemical technique and demonstrated that Oligodendrocytes and myelin were stained in densely myelinated brain regions but the staining occurred in patches rather than uniformly throughout densely myelinated tracts. This study further modified the iron histochemistry technique to establish that Oligodendrocytes and myelin are enriched in iron throughout densely myelinated tracts. This finding supports biochemical studies that detected high levels of iron in white matter (Hallgren and Sourander, J Neurochem 3:41–51, 1958) and myelin fractions of brain homogenates (Rajan et al., Life Sci 18:423–432, 1976). Thus, this histochemical study and earlier biochemical studies indicate that white matter is a major site of iron concentration within the brain. The present study also examined the distribution of iron in Oligodendrocytes and myelin from the dysmyelinating mutant mice quaking and shiverer. Results from these studies demonstrate that Oligodendrocytes and myelin are enriched in iron in both quaking and shiverer brains. An unexpected finding was an intense staining of oval structures within the oligodendrocyte cytoplasm. This result indicates a concentration of iron in these structures and may be important for understanding how high concentrations of iron are processed by Oligodendrocytes.
Cell adhesion properties of myelin‐associated glycoprotein in L cell fibroblasts
Authors: Afar D. E. H. , Marius R. M. , Salzer J. L. , Stanners C. P. , Braun P. E. , Bell J. C. 
Published: January 2005

AbstractMyelin‐associated glycoprotein (MAG) is a cell surface molecule expressed by oligodendrocytes and Schwann cells. In order to determine whether MAG expression can confer adhesive properties to cells which normally do not aggregate in suspension, the cDNA encoding the long form of MAG (L‐MAG) was introduced into L cell fibroblasts by retroviral infection. Clonal L cell lines expressing MAG were then subjected to a cell aggregation assay. Our results indicate that L‐MAG can function as an intercellular adhesion molecule in a heterologous cell system. A critical threshold value of L‐MAG expression was required for cell aggregation to occur. The adhesive properties of these cells were specific to MAG, since monoclonal antibodies directed against its extracellular domain inhibited aggregation. Furthermore, the adhesion was found to be calcium‐ and temperature‐independent. Cell sorting experiments demonstrated that L‐MAG‐expressing cells bind in a heterotypic fashion to parental L cell fibroblasts. These results suggest that L‐MAG can function as a heterotypic cell adhesion molecule recognizing a cell surface mole‐cule(s) expressed by L cells.
Neuronal specific protein NP185 is enriched in nerve endings: Binding characteristics for clathrin light chains, synaptic vesicles, and synaptosomal plasma membrane
Authors: Su B. , Hanson V. , Perry D. , Puszkin Saul 
Published: January 2005

AbstractThe neuronal specific protein NP185, found associated with brain clathrin‐coated vesicles, formed a complex with unphosphorylated, but not with phos‐phorylated, clathrin light chains. The NP185–clathrin light chain complex was associated with casein kinase II activity, which, in the presence of polylysine, phosphorylated clathrin light chain b but not the NP185. The dissociation of this complex with 50% ethylene glycol pH 11.5 suggests that NP185binds to hydrophobic domains of clathrin light chains. When NP185 molecules were retained by monoclonal antibody‐linked Sepharose beads, they bound synaptic vesicles, decoated vesicles and synaptosomal plasma membrane. Immunohistochemistry on mouse cerebellar tissue sections using 8G8, a monoclonal antibody raised against NP185, showed neuronal specific labeling closely following synaptic distribution. In immunoblots, NP185 shares similar epitopes to those detected in another assembly polypeptide, AP‐180, an indication that both proteins are identical. It appears that NP185 plays a specific role in nerve ending functions through its ability to induce clathrin to polymerize into cages, its interaction with synaptic vesicles, with the plasma membrane and with clathrin coat components.
Actin‐depolymerizing factor (ADF) in the cerebellum of the developing rat: A quantitative and immunocytochemical study
Authors: Léna J. Y. , Bamburg J. R. , Rabié A. , Faivre‐Sarrailh C. 
Published: January 2005

AbstractA specific antiserum against actin‐depolymerizing factor (ADF) was used in a quantitative and immunocytochemical study of ADF in the cerebellum of developing rats. The Triton‐soluble ADF concentration remained stable throughout development. Light and electron microscopic immunocytochemistry showed that ADF was not detected in all cerebellar cells. ADF immunoreactivity was found in Purkinje cells, but not in granule cells. It was found in the Bergmann astrocytes and the astrocytes of the white matter, but not in the oligodendrocytes. The cell bodies and dendrites of Purkinje cells were immunoreactive for ADF but the axons were not. In contrast, the other axons of the white matter (mossy and climbing fibres) were labeled. Thus, ADF was not restricted to either the dendritic or axonal compartments. However, dendritic spines and postsynaptic densities were immunoreactive, whereas presynaptic varicosities were unlabeled. The immunoreactivities for ADF and actin were compared. ADF staining was uniformly distributed throughout the entire dendritic arborization of the Purkinje cell, while filamentous actin is highly concentrated in the dendritic spines, indicating that ADF activity might vary according to its cellular localization.
NF‐L and peripherin immunoreactivities define distinct classes of rat sensory ganglion cells
Authors: Goldstein M. E. , House S. B. , Gainer H. 
Published: January 2005

AbstractDouble immunofluorescence studies using antibodies against NF‐L and peripherin revealed three distinct subpopulations of neurons in rat dorsal root ganglia (DRG). In the adult rat, 46% of the DRG neurons were small and peripherin‐positive (NF‐L‐negative), and 48% were large and NF‐L‐positive (peripherin‐negative). About 6% were both peripherin‐ and NF‐L‐positive. All of the DRG neurons reacted with antibodies to NF‐M and nonphosphorylation‐dependent or phosphorylation‐independent antibodies to NF‐H. The neuropeptides were predominantly found in the peripherin‐positive small cell population. Eighty‐seven percent of the peripherin‐positive small cell population contained substance P immunoreactivity, while 43% of this cell population contained CGRP. In contrast, only 18–24% of the NF‐L‐positive large‐cell population contained neuropeptides, and these were primarily in a smaller sized subpopulation. Similar patterns of antigen representation were observed in neonatal (PN2) DRG cell populations. Tissue cultures of sensory ganglion cells from PN2 DRG, in serum‐free medium, stably maintained exclusively peripherin‐positive neurons, with about 5% of these containing coexistent NF‐L immunoreactivity. Very high levels of neuropeptide gene expression were exhibited by these postnatal neurons in culture.
Aberrant localization of MAP5 immunoreactivity in the hippocampal formation in alzheimer's disease
Authors: Geddes J. W. , Lundgren K. , Kim Y. K. 
Published: January 2005

AbstractImmunocytochemistry was used to examine MAP5 immunoreactivity in the hippocampal formation obtained postmortem from five elderly, normal individuals, six individuals with Alzheimer's disease (AD), and two “transition” cases that did not have a history of dementia but did exhibit significant AD pathology. In all of the cases examined, axonal staining was restricted to the mossy fibers and their terminal field in CA3 stratum lucidum. In control cases, MAP5 immunoreactivity was observed in the neuronal cytoplasm and the proximal portion of the apical dendrites of pyramidal and granule cells. In both AD and transition cases, increased intensity of immunostaining was observed in CA3 pyramidal, subicular, and dentate gyrus granule cell neurons. Within individual neurons, immunoreactivity filled the neuronal perikarya, including the nuclear region, and the apical dendrite. Punctate staining was observed in neuritic plaques, but neurofibrillary tangles and neuropil threads were not immunostained.The increase and altered distribution of MAP5 immunoreactivity in both vulnerable and nonvulnerable neurons in AD may reflect an aberrant sprouting response. The increased expression of early cytoskeletal proteins may be tolerated in some regions such as CA3, but not in others including CA1 where the increased expression appear to precede aberrant phosphorylation, proteolysis, and incorporation of cytoskeletal proteins into AD pathology. Alternatively, the results could reflect sprouting in response to the neuronal loss and degeneration.
Local control of axonal properties by schwann cells: Neurofilaments and axonal transport in homologous and heterologous nerve grafts
Authors: De Waegh S. M. , Brady S. T. 
Published: January 2005

AbstractA number of axonal properties, including slow axonal transport and neurofilament phosphorylation, are altered in a mutant mouse strain with a Schwann cell deficiency, the Trembler. The Trembler phenotype is associated with poor myelination and reduced axonal caliber in the peripheral nervous system, but the genetic lesion has not yet been identified. To determine whether changes in axonal properties resulted from a direct action of Schwann cells on the axon, a segment of sciatic nerve from myelin‐deficient Trembler mouse was grafted into the sciatic nerve of a normal mouse and normal axons were allowed to regenerate. Normal axons surrounded by Trembler Schwann cells are reduced in diameter, but resume their original diameter distal to the graft. Neurofilament transport was also affected locally in sciatic nerves with Trembler grafts into normal nerve. The velocity of neurofilament transport was not significantly different from controls in portions of the nerve proximal to the Trembler graft, but there was a reduction in neurofilament transport rates upon entering the Trembler graft. This was accompanied by an increase in the ratio of neurofilament over tubulin in the case of the Trembler graft, suggesting both a slowing of the neurofilament and an increase in the rate of tubulin transport. Using heterologous grafts of Trembler nerve segments into wild type nerves, Schwann cells were shown to locally influence axonal caliber, neurofilament organization, and slow axonal transport. These observations emphasize the importance of glial cells in modulating neuronal structure and functions, as well as focusing attention on the role of glia in the etiology of neuropathologies that alter the neuronal environment.
Interaction between cAMP elevation, identified growth factors, and serum components in regulating Schwann cell growth
Authors: Stewart H. J. S. , Eccleston P. A. , Jessen K. R. , Mirsky R. 
Published: January 2005

AbstractMost previous studies on Schwann cell proliferation in vitro have used serum‐containing media. This complicates the analysis of agents required for cell division since serum contains an ill‐defined mixture of hormones and growth factors. Serum‐free medium has therefore been used to analyse the response of Schwann cell to previously identified Schwann cell mitogens.Serum factors were not necessary for DNA synthesis in response to platelet‐derived growth factor, basic fibroblast growth factor, or glial growth factor, provided they were used in combination with forskolin to elevate intracellular cAMP. Transforming growth factor β1, a Schwann cell mitogen in serum, was not mitogenic under these conditions. Neither the growth factors nor forskolin were effective when used alone. Growth control was analysed further using long‐term cultured Schwann cells that had spontaneously immortalized. Measurements of endogenous cAMP levels in short‐ and long‐term Schwann cells revealed that long‐term cells had two to three times higher basal cAMP levels. As predicted by these findings, platelet‐derived growth factor, basic fibroblast growth factor, and glial growth factor stimulated DNA synthesis in long‐term cells without requiring costimulation by agents which elevate cAMP (while transforming growth factor β1 had no effect).These results show first that in rat Schwann cells activation of at least two intracellular pathways, one of which is cAMP dependent, is required for stimulation of DNA synthesis, second that serum factors are not necessary for the synergy between cAMP and platelet‐derived growth factor, basic fibroblast growth factor, or glial growth factor, and third that the mitogenic stimulation by transforming growth factor β1 is more complex, requiring serum factors in addition to elevation of cAMP.
Correlation between morphological and biochemical effects of ethanol on neuroblast‐enriched cultures derived from three‐day‐old chick embryos
Authors: Kentroti S. , Vernadakis A. 
Published: January 2005

AbstractWe have shown that ethanol exposure during embryogenesis affects a variety of parameters of neuronal growth. In this study we examined the direct effects of ethanol exposure on developing neuroblasts in culture. Neuroblast‐enriched cultures derived from 3‐day‐old whole chick embryos were grown in the presence of ethanol at doses ranging from 12.5 to 50 mM from culture day 3–14. Cholinergic and GABAergic phenotypic expression were both significantly reduced following ethanol exposure as assessed by the activities of choline acetyltransferase and glutamate decarboxylase, respectively. Morphometric analysis of the growth patterns showed significant differences between control and ethanol‐treated cultures. Control cultures exhibited the characteristic pattern of growth consisting of neuronal aggregation with neuritic arborization, i.e., neuritic bundles and fasciculation. Cultures grown in ethanol from culture day 3 consisted of aggregates that measured significantly greater in size than those observed in control cultures. In addition, in ethanol‐treated cultures, the primary pattern of neuritic bundles was replaced by a complex network of individual neurites radiating from the central aggregate, forming a defined “neuritic field.” Morphometric analysis revealed that both neurite number and neurite length were significantly reduced in ethanol‐treated cultures. The biochemical data confirm earlier reports from this laboratory suggesting that ethanol exposure during early embryogenesis alters the normal neuronal pattern of phenotypic expression. In addition, we have presented evidence in this study that ethanol alters the morphological growth patterns of developing neurons. Although ethanol does not alter the ability of these cells to aggregate, there is a significant alteration in neuritic outgrowth. We conclude that the alterations in the growth patterns induced by ethanol hinder full neurotransmitter phenotypic expression.
Molecular cloning of NILE glycoprotein and evidence for its continued expression in mature rat CNS
Authors: Prince J. T. , Alberti L. , Healy P. A. , Nauman S. J. , Stallcup W. B. 
Published: January 2005

AbstractThe NILE glycoprotein is a rat neuronal cell adhesion molecule which has been reported to be very similar in structure, function, and distribution to the mouse L1 glycoprotein. Here we report the complete nucleotide sequence of the NILE message (5,208 nucleotides) and the deduced amino acid sequence of the NILE polypeptide (1,257 amino acids). The predicted NILE protein is 96% identical to L1 at the amino acid level, confirming that the two molecules are homologues. The sequence information shows that NILE is a transmembrane molecule with an extensive ectodomain and a much smaller cytoplasmic domain. The extracellular portion of the molecule contains six immunoglobulin C‐2 type domains followed by five fibronectin type III repeats. These two structural motifs are characteristic of several other cell adhesion molecules. The cytoplasmic tails of NILE and L1 are identical to each other and distinct from the cytoplasmic regions of all other cell adhesion molecules except Ng‐CAM and neuroglian. Several possible sites for phosphorylation are present in the cytoplasmic tail of NILE.Antisera were produced against two NILE‐β‐galactosidase fusion proteins containing distinct segments of the NILE polypeptide: the cytoplasmic domain and the segment containing fibronectin type III repeats. Immunoblots with these antisera and Northern blots with a NILE cDNA probe indicate that NILE continues to be expressed in most areas of the mature rat brain. This contradicts previous immunofluorescence data, which suggested that NILE was substantially down‐regulated in maturing nerve fiber tracts. This raises the possibility that NILE could be masked in situ by interactions with other cell surface molecules.
A subpopulation of bone marrow‐derived macrophage‐like cells shares a unique ion channel pattern with microglia
Authors: Banati R. B. , Hoppe D. , Gottmann K. , Kreutzberg G. W. , Kettenmann H. 
Published: January 2005

AbstractRat microglia share a number of antigenic, functional, and morphological similarities with macrophages from other tissues, but are characterized by a distinctly different pattern of ion channels in the cellular membrane (Kettenmann et al., J Neurosci Res 26:278–287, 1990). Macrophages typically express outward and inward K+ currents. In contrast, microglia lack outward currents and only show inwardly rectifying K+ currents, regardless of the isolation or cultivation method employed for microglia. In this study we demonstrate that a subpopulation of bone marrow‐derived macrophage‐like cells possesses inward rectifier K+ currents, but no outward currents and thus with regard to the electrophysiological characteristics closely resembles microglia. A second population of bone marrow‐derived macrophage‐like cells shows the usual channel pattern described for other body macrophages. Our results strengthen the hypothesis that in the bone marrow distinct pools of precursor cells exist, possibly reflecting an early differential lineage determination for body and brain macrophages, i.e., microglia.
β‐Adrenergic treatment of C6 glioma cells produces opposite changes in c‐fos and c‐jun mRNA levels
Authors: Gubits R. M. , Yu H. 
Published: January 2005

AbstractThe AP1 transcriptional complex is a heterodimer composed of proteins encoded by the fos and jun proto‐oncogene families. Changes in the concentration and composition of AP1 occur after cells are perturbed in a variety of different ways (Curran, in Reddy et al., eds. “The Oncogene Handbook,” Amsterdam: Elsevier, pp 307–325, 1988; Sonnenberg et al., Neuron 3:359–365, 1989). Transient changes in AP1 conlent presumably result in altered expression of AP1‐regulated targel genes, that help to mediate the cell's long‐term response to changes in its environment. One factor that may be important in determining which target genes are regulated by AP1 in a given context is the identity of the jun family member present in the complex (Chiu et al., Cell 59:979–986, 1989; Schutte et al., Cell 59:987–997, 1989). Fos induction has been demonstrated after binding of β‐adrenergic ligands to their cell surface receptors (Barka et al., Mol Cell Biol 6:2984–2989, 1986; Gubits et al., Mol Brain Res 6:39–45, 1989; Arenander et al., J Neurosci Res 24:107–114, 1989; Mocchetti et al., Proc Natl Acad Sci USA 86:3891–3895, 1989). However, the response of the jun gene family to this treatment has not been reported. We have therefore examined the effect of β‐adrenergic receptor activation on the expression of c‐fos, c‐jun, and junB mRNA levels in C6 glioma cells. Our results indicate that c‐fos and junB mRNA levels are increased by 52‐ and 2.7‐fold, respectively, after 45 min of isoproterenol (IPR) treatment. Unexpectedly, we found a concomitant decrease in c‐jun mRNA levels of about 2.5‐fold. The changes in c‐fos and c‐jun mRNAs were found to be dose dependent and specifically mediated by β‐ rather than alpha‐adrenergic receptors. The alterations in AP1 composition implied by our findings suggest a role for this transcriptional complex in mediating late gene responses lo β‐adrenergic receptor activation.