bluuebunny/crossref_metadata_2025_split huggingface dataset:
Amino acid content of rat cerebral astrocytes adapted to hyperosmotic medium in vitro
Authors: Olson J. E. , Goldfinger M. D. 
Published: January 2005

AbstractRat cerebral astrocytes from confluent primary cultures were grown for two weeks in medium made hyperosmotic with additional NaCl. At the time the cells were harvested (four weeks in culture), the medium osmolality of experimental cultures was approximately 600 mOsm. Amino acid, protein, and potassium contents and the cell volume were measured. Compared to cells maintained in control medium (approximately 300 mOsm), cells grown in hyperosmotic conditions had over two times the content of taurine and five times the content of glutamine. Alanine, aspartate, glutamate, glycine, and tyrosine contents also were elevated in these hyperosmotic‐treated cells, while asparagine contents were unchanged relative to control cells. Cell volume and potassium contant were decreased to approximately 50% of control levels by the hyperosmotic treatment while total protein content per cell was unchanged relative to cells from control cultures. Seven min after hyperosmotic‐exposed cells were rapidly diluted into PBS with osmolality equal to about 330 mOsm, cell contents of alanine, asparagine, glutamine, glutamate, glycine, taurine, and tyrosine fell toward control levels. The data indicate that significant alterations in intracellular osmolytes occur in astrocytes adapted to hyperosmotic conditions. We suggest that a loss of intracellular potassium is at least partially compensated by accumulation of taurine, glutamine, and perhaps other amino acids acting as intracellular osmolytes.
Production of colony‐stimulating factor‐1 (CSF‐1) by mouse astroglia in vitro
Authors: Hao C. , Guilbert L. J. , Fedoroff S. 
Published: January 2005

AbstractWe investigated whether astroglia produce any of the known macrophage growth factors, CSF‐1, GM‐CSF, and IL‐3, and if so, whether any of these cytokines stimulate the growth of CNS macrophages. In this work we used highly enriched cell cultures of C3H/HeJ mouse neopallium: cultures of astroglia and cultures of macrophage‐like cells derived from nutritionally deprived astroglia cultures.We found that astroglia in cultures accumulate in the medium, an activity that stimulates the proliferation of macrophage‐like cells. The activity has been identified as CSF‐1 by using growth assays of cells dependent and nondependent on CSF‐1, and by radioreceptor analysis which is highly specific for CSF‐1. Northern blot analysis demonstrated the presence in astroglia of CSF‐1 mRNA and the presence of CSF‐1 receptor (c‐fms) mRNA in macrophage‐like cells but not in astroglia. The astroglia did not produce GM‐CSF or IL‐3. We concluded that a paracrine relationship exists between astroglia production of CSF‐1 and the response of macrophage‐like cells to the cytokine in culture.
Glial cells of the human developing brain and B cells of the immune system share a common DNA binding factor for recognition of the regulatory sequences of the human polyomavirus, JCV
Authors: Major E. O. , Amemiya K. , Elder G. , Houff S. A. 
Published: January 2005

AbstractCells of the nervous system and the immune system perform phighly specialized functions which reflect the tissue‐specific regulation of their genes. However there are some functions between these two cell systems such as antigen presentation, cytokine release, and expression of MHC molecules which suggest a common mechanism for regulation of certain genes. We present data that extend this observation to in clude the recognition of specific neurotropic viral DNA sequences by glial cells and B cells. The experiments here provide evidence that both human glial cells and B cells possess nuclear DNA binding proteins that interact with nucleotide sequences on the regulatory region of the JC viral genome. These DNA binding proteins are present in human lymphoma B cell lines and fetal glial cultures. The fetal glial cultures are characterized as astrocytes by unique cDNA expression and the presence of GFAP. Data are also presented that demonstrate the presence of JCV infected B cells in brain tissue derived from progressive multifocal leucoehcephalopathy, the demyelinating disease caused by JCV infection. The possibility that the glial and B cell protein factor(s) responsible for recognition of the JCV genome belong to a family of proteins similar to known transcriptional control elements such as the Octamer binding proteins or Nuclear Factor‐1 is discussed.
PET demonstrates different behaviour of striatal dopamine D‐1 and D‐2 receptors in early Parkinson's disease
Authors: Rinne J. O. , Laihinen A. , Någren K. , Bergman J. , Solin O. , Haaparanta M. , Ruotsalainen U. , Rinne U. K. 
Published: January 2005

AbstractStriatal dopamine D‐1 receptor binding was investigated in vivo with positron emission tomography (PET) in five patients with early. Parkinson's disease using [11C]‐SCH 23390. All patients had predominantly unilateral symptoms and showed a significant reduction in the accumulation of [18F]‐6‐F‐DOPA in the striatum contralateral to the symptoms. None of the patients had received any antiparkinsonian medication. The striatal and cerebellar radioactivity was measured and corresponding striatum/cerebellum ratios were counted. The mean striatum/cerebellum ratio of [11C]‐SCH 23390 binding was symmetric be‐tween the hemispheres. By contrast, the striatum/cerebellum ratio of [11C]raclopride binding, labelling dopamine D‐2 receptors, was increased significantly in the hemisphere contralateral to the symptoms as compared with the opposite hemisphere. Thus, the present results show that the behaviour of striatal D‐1 and D‐2 receptors is different in early Parkinson's disease.
Neurochemical aspects on aging and diseases with cognitive impairment
Authors: Gottfries C. G. 
Published: January 2005

AbstractThe concentrations of monoamines and cholineacetyl transferase (CAT) are reduced in brains from patients with normal aging. According to findings about the dopamine (DA) system, the age‐sensitive decrease has its onset in the 60s and after that has a continuous progress. In patients with Alzheimer's disease (AD/SDAT), multiple changes indicate disturbed metabolism in the acetylcholine (ACh), DA, noradrenaline (NA), and 5‐hydroxytryptamine (5‐HT) systems. The activity of monoamine oxidase B (MAO‐B) increases significantly with age and a further‐increase has been reported to occur in Alzheimer‐afflicted brains. In the platelets, too, there is increased MAO‐B activity in AD/SDAT patients. Increased enzyme activity is considered a marker of gliosis in the brain and a marker of macrocytosis in platelets. Gangliosides are reduced in several areas of the brain in AD/SDAT patients, which indicates a reduction of nerve terminals. Significantly reduced concentrations of myelin components have also been recorded in brains from patients with AD/SDAT, which is in agreement with histopathological findings.The neurochemical changes recorded in brains from normally aged individuals are very similar to those found in AD/SDAT brains, although the latter changes are more‐severe. Thus, it has been suggested that the pathological process in AD/SDAT may be an exacerbation of the process taking place in normal aging.The multiple neurochemical changes recorded in grey, as well as in white matter must still be considered changes of secondary nature. At the present level of knowledge, it is not possible to single out any one of these changes as of special etiological importance. In the brains of patients with AD/SDAT, more fundamental disturbances must be considered, the nature of which we still do not know. It should also be emphasized that the pathological changes in the central nervous system reported in patients with AD/SDAT have, to some extent, also been found outside the brain, indicating that the pathological process in AD/SDAT is a general process to which the central nervous system is possibly especially sensitive.
Cholinergic receptors in human brain: Effects of aging and alzheimer disease
Authors: Giacobini E. 
Published: January 2005

AbstractA general review of cholinergic receptors in human brain is presented. The paper focuses upon changes in normal aging brain and in Alzheimer disease. Studies from five different approaches are reported: (1) molecular biology; (2) receptor binding studies; (3) studies with specific neurotoxins; (4) immunocyto‐chemistry; and (5) PET scan. These studies document profound and characteristic differences between the normal aging and the pathological Alzheimer brain with regard to cholinergic receptor localization, distribution, and function.
Kinesin heavy chain from bovine brain and Drosophila appear to be highly homologous molecules
Authors: Green L. A. D. , Kaplan M. P. , Liem Ronald K. H. 
Published: January 2005

AbstractA microtubule‐enriched fraction was prepared from bovine white matter, and kinesin and other microtubule‐associated proteins were extracted from taxol‐stabilized microtubules by homogenization and ultracentrifugation in the presence of nucleotides (guanosine triphosphate and adenosine triphosphate). The kinesin‐enriched fractions were subjected to preparative SDS‐PAGE, and the band representing the kinesin heavy chain was excised, homogenized, and subjected to partial enzymatic digestion with Staphylococcus aureus V8 protease. Four peptides were selected for sequence analysis and compared to the previously published sequence for the Drosophila kinesin heavy chain (Yang JT, Laymon RA, Goldstein LSB, Cell 56:879–889, 1989). All four peptides matched closely with portions of the Drosophila sequence corresponding to the central, α‐helical domain. Total amino acid composition analysis of bovine kinesin heavy chain also reveals a high degree of homology to the Drosophila sequence.
Specificity of human T cell clones reactive to immunodominant epitopes of myelin basic protein
Authors: Chou Y. K. , Henderikx P. , Vainiene M. , Whitham R. , Bourdette D. , Chou C. H.‐J. , Hashim G. , Offner H. , Vandenbark A. A. 
Published: January 2005

AbstractSeveral recently discovered lines of evidence support the involvement of myelin basic protein (BP)‐specific T cells in multiple sclerosis (MS). To identify potentially relevant immunodominant T cell epitopes, human BP (Hu‐BP)‐reactive T cell lines were selected from MS and normal donors and tested for reactivity to cleavage fragments and synthetic peptides of Hu‐BP. The MS T cell lines responded to more Hu‐BP epitopes than did normal lines, showing biased recognition of the N terminal half of the molecule, and one region in the C terminal half, suggesting increased sensitization to BP. The MS lines also differed from normal lines in their decreased percentage of CD8 + cells. One hundred nine T cell clones isolated from these lines confirmed the reactivity pattern of the lines but did not reflect the mixed phenotype, since all but three clones tested were CD4+. T cell clones from HLA‐DR2 homozygous donors responded to a variety of epitopes, indicating that this molecule was permissive in its ability to restrict T cell responses. Other epitopes, including the immunodominant 149‐170 sequence, were restricted by several different major histocompatibility complex (MHC) molecules from both MS and normal donors. T cell receptor (TCR) V gene products could be identified on six of 38 clones tested using monoclonal antibodies. From one HLA‐DR2 homozygous donor, four of eight clones utilized Vβ5.2 in response to different BP epitopes, providing initial support for the preferential use of a limited set of V region genes in the human response io BP. Preferential TCR V gene use in MS patients would provide the rationale to regulate selectively BP‐reactive T cells through immunity directed at the TCR and thus test for the first time the hypothesis that BP‐reactive T cells play a critical role in the pathogenesis of MS.
Regulation of heat shock protein synthesis in rat astroeytes
Authors: Dwyer B. E. , Nishimura R. N. , De Vellis J. , Clegg K. B. 
Published: January 2005

AbstractRat forebrain astrocytes synthesize heat shock proteins with molecular weights 97,89,70,68, and 30‐34 kilodaltons. The stress inducible 68‐kDa heat shock protein (HSP‐68) was vigorously expressed by astro‐cytes in culture after a 45°C, 20 min heat shock. HSP‐68 synthesis was poorly inducible by a second heat shock given 16 hr after the initial heat shock. Decreased [35S]methionine incorporation into HSP‐68 correlated with low levels of HSP‐68 mRNA present after the second heat shock. The data suggest that control of HSP‐68 mRNA levels by transcriptional/ posttranscriptional mechanisms is a major site for regulation of HSP‐68 synthesis.
Proliferation of chick embryo neuroblasts grown in the presence of horse serum requires exogenous transferrin
Authors: Barakat‐Walter I. , Deloulme J. C. , Sensenbrenner M. , Labourdette G. 
Published: January 2005

AbstractWe have previously shown that neuroblasts from cerebral hemispheres of 6‐day‐old chick embryos are able to proliferate when grown in the presence of fetal calf serum. We report here that in the presence of horse serum alone the proliferative rate of neuroblasts is strongly reduced. A high proliferative rate is restored upon the addition of bovine transferrin and to a lesser extent with added FeSO4 or hemin. These findings suggest that the transferrin of horse serum cannot be used by chick neuroblasts in vitro, while bovine transferrin exogenously added is active in promoting cell proliferation. We propose that the stimulatory activity of the fetal calf serum is due to bovine transferrin, since when this serum is fractionated by gel filtration, the fractions that stimulate the proliferation of neuroblasts grown in the presence of horse serum are located in the molecular weight area of transferrin, and they do contain transferrin as seen by immunoblotting with a specific anti‐transferrin antibody.
Brief chronic effects of lithium administration on rat brain phosphoinositides and phospholipids
Authors: Navidi M. , Yoa F.‐G. , Sun G. Y. 
Published: January 2005

AbstractLithium is known to exert its biochemical action on cells and tissues by inhibiting the enzymic conversion of inositol monophosphates to inositol. However, it is not clear whether this inhibitory action may lead to changes in the de novo biosynthesis of phosphatidylinositol and its phosphorylated derivatives. This biosynthetic scheme may have an important bearing with regard to the receptor‐mediated signal transduction mechanism involving hydrolysis of polyphosphoinositides and release of inositol trisphosphate as second messenger for mobilization of intracellular calcium. In this study, the effects of brief chronic lithium administration on metabolism of brain phosphoinositides and other phospholipids were examined using the radiotracer technique with 32Pi as precursor. Sprague Dawley rats that were treated with lithium (3‐4 meq/kg body wt) twice daily for 2‐6 days consistently indicated an increase in the labeling of phosphatidylinositol 4,5‐bisphosphates and a decrease in labeling of phosphatidylinositols and phosphatidylethanolamines. These phosphoiipid changes were found in both cortex and hippocampus and appeared to occur primarily in the synaptosomal fraction. Although the extent of the phosphoiipid changes could vary depending on both duration and dose levels of the lithium administered, these results demonstrated subtle effects of lithium on depressing the biosynthesis of phosphatidylinositol as well as phosphatidylethanolamine but perhaps a compensative increase in the synthesis of the phosphatidylinositol 4,5‐bisphosphates.
Characteristics of excitatory amino acid uptake in cultures from neurons and glia from the retina
Authors: Somohano F. , López‐Colomé A. M. 
Published: January 2005

Abstract3H‐D‐Aspartate uptake was biochemically characterized in cultures from chick retina enriched in glial (Müller) cells or neurons during progressive days in vitro (DIV). In the neuronal cultures a high‐affinity, Na+‐dependent system was found with Km = 8–13 μM and pharmacological characteristics in agreement with those of reuptake systems in other regions of the CNS. The uptake system in glial cells showed a lower affinity, with Km = 100–135 μM. In both cases, uptake wastemperature and energy dependent. A sharp increase in the Vmax of uptake was observed in both neuronal and glial cultures at 5 DIV, at which time morphologically mature synapses have been shown to be present in retinal cultures. A parallel increase in the pharmacological specificity of the uptake system in neuronal cultures was observed, with a rise in the efficiency of D‐Asp, L‐Asp, L‐Glu, and DL‐asp‐ β‐hydroxamate for inhibiting 3H‐D‐As‐partate uptake. Results suggest the possibility of re‐uptake participating in the regulation of extracellular glutamate concentration during development.
Transfer of 45Ca and 36Cl at the blood‐nerve barrier of the sciatic nerve in rats fed low or high calcium diets
Authors: Wadhwani K. C. , Murphy V. A. , Rapoport S. I. 
Published: January 2005

AbstractUnidirectional fluxes of 45Ca, 36C1, of [3H]mannitol from blood into the sciatic nerve and cerebral cortex were determined from 5‐ and 15‐min uptakes of these tracers after an intravenous (i.v.) bolus injection in awake rats. Rats were fed diets for 8 wk, that had either a low (0.01%wt/wt), normal (0.67%), or high (3%) Ca content. Plasma[Ca] was 32% less and 11% more in rats fed low (LOCA) and high Ca diets (HICA), respectively, than in rats fed a normal Ca diet (CONT). The mean permeability‐sur‐face area product (PA) of 45Ca at the blood‐nerve barrier was about eightfold higher than at the blood‐brain barrier in the same animals and did not differ significantly between groups (<0.05). Mean PA ratios of 45Ca/36Cl barriers in CONT rats, 0.52±0.04 and 0.40±0.02, respectively, were not significantly different from corresponding ratios in LOCA and HICA groups, and corresponded to the aqueous limiting diffusion ratio (0.45), Our results show no evidence for concentration‐dependent transport of Ca over a plasma [Ca] range of 0.8‐1.4 mmol/liter at the blood‐nerve barrier of the rat peripheral nerve, and suggest that Ca and Cl exchange slowly between nerve and blood via paracellular pathways.
In vitro changes in the fine structure and protein composition of light myelin fractions isolated from guinea pig brain
Authors: Nunzi M. G. , Chan K.‐F. J. , Webster Henry deF. 
Published: January 2005

AbstractTo find out if in vitro maintenance produces changes in the electron microscopic appearance, protein composition, and phosphorylation properties of guinea pig CNS myelin fractions, we incubated them for 10 min, 4 hr, 24 hr, and 48 hr in phosphate‐buffered saline (pH 7.4) or in 20 mM Hepes, 2 mM EDTA, 0.5 mM EGTA, 0.5 mM dithiothreitol, and 20 mM NaCl at 4 and 30°C. Aliquots were processed for electron microscopic study, were analyzed for protein content by gel electrophoresis, and were assayed for endogenous protein phosphorylation. Before incubation, electron micrographs of fractions contained two types of multilamellar whorls with the periodicity of CNS myeiin sheaths. The first type of whorl was separated from nearby whorls; the other type had surface lamellae that were connected to other multilayered membrane fragments. After incubation at 4°C for 24 hr, the number of both types of multilamellar whorls in micrographs had increased approximately 3‐ to 4‐fold. Counts per unit area showed that the observed increase was both time‐ and temperature‐dependent. In aliquots studied by gel elect, ophoresis, only minor degradation of myeiin proteins was observed. The endogenous protein phosphorylation properties of the myeiin fragments also remained functional, suggesting that the activities of protein phosphotransferases were not altered. We conclude that the incubation conditions described here favor interactions of proteins and lipids that lead to the formation of multi‐layered aggregates of CNS myeiin membranes.
Increased release of an amyloidogenic C‐terminal Alzheimer amyloid precursor protein fragment from stressed PC‐12 cells
Authors: Baskin F. , Rosenberg R. N. , Greenberg B. D. 
Published: January 2005

AbstractAmyloid plaques, found in characteristically large numbers in specific brain areas of Alzheimer's disease (AD) and Down's Syndrome (DS) patients, are composed of a 417–43 amino acid peptide, A4, derived from a transmembrane glycoprotein, amyloid precursor protein (APP). In transformed cells APP has been shown to be cleaved within the extracellular portion of the A4 region causing the release of 100–120 kDa soluble N‐terminal APP products. If this cleavage occurs in human tissue, neither the soluble product nor the remaining 10–12 kDa transmembrane fragment could be further degraded to yield A4. It has been hypothesized that an alternate APP cleavage product containing the intact A4 region is released in increased amounts in AD and DS brain where subsequent extracellular degradation produces the amy‐loidogenic A4 peptide.In support of this hypothesis, we have found that PC‐12 cells maintained in serum‐free media with or without additional injurious agents release a 60 kDa protein which has been detected by immunoprecipitation and immunoblot analyses with 9 antisera elicited by 4 distinct peptides within the carboxyl‐terminal half of APP. Six of these antisera, elicited by peptides corresponding to the carboxyl‐terminal 20 amino acids of APP, or the A4 peptide itself, do not bind the normally released 120 kDa APP product which is detected by 11 other antisera elicited by peptides with the N‐terminal portion of APP. Controls in which two 60 kDa‐detecting antisera were preabsorbed with the peptides used to elicit them, produced markedly reduced 60 kd bands on immunoblots. Thus, the 60 kDa protein appears to be the first reported APP product released from neural cells which, containing the intact A4 region, is potentially amyloidogenic.Similar analyses of proteins released into the serum‐free media of PC‐12 cells maintained in 0.0030.005% SDS, 60 mM chloroquine, or other membrane damaging or lysosomal inhibiting agents revealed increased 60 kDa band intensities. Cultures grown with other classes of injurious agents did not demonstrate increased release. Together these data indicate that neural cells maintained under selected stressful or injurious conditions release increased quantities of a potentially amyloidogenic APP product, supporting the importance of a similar induction of alternative APP cleavage in AD and DS brain amy‐loidogenesis.
Possible neurotransmitter role of noradrenaline in the teleost retina
Authors: Jaffe E. H. , Urbina M. , Drujan B. D. 
Published: January 2005

AbstractThe role of dopamine as a neurotransmitter in the retina of different species has been clearly established; however, there is still some controversy as to whether noradrenaline (NA) is present as a neurotransmitter in this tissue. In this study, we show that, under controlled conditions, NA is present in the retina of goldfish at a concentration of 0.15±0.03 ng/ mg protein and its biosynthetic enzyme, dopamine‐β‐hydroxylase shows an activity of 2.5±0.2 pmol NA/hr/mg protein. The amount of NA increases to 1.88±0.24 ng/mg protein in light adapted animals and decreases to undetectable levels in dark adapted ones. By contrast, dopamine±β‐hydroxylase levels are not affected by changes in light conditions. This finding provides further evidence in favor of a neurotransmitter role for NA in vertebrate retina.