bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calmodulin antagonists chlorpromazine and W‐7 inhibit exogenous cholesterol esterification and sphingomyelinase activity in human skin fibroblast cultures. Similarities between drug‐induced and niemann‐pick type C lipidoses
Authors: Masson M. , Spezzatti B. , Chapman J. , Battisti C. , Baumann N. 
Published: January 2005

AbstractIn this report we showed that calmodulin antagonists chlorpromazine (CPZ) and W‐7 (N‐[6‐ aminohexyl]‐5‐chloro‐1‐naphtalenesulfonamide), when added to fibroblast cell cultures, gave rise to a time‐ and dose dependent decrease of sphingomyelinase activity. CPZ and W‐7 also significantly inhibited LDL‐ and non‐LDL‐ dependent cholesterol esterification. Addition of these drugs to cell culture medium mimicked what is observed in the genetic disease Niemann‐Pick type C.H‐7 (1‐[5‐isoquinonylsulfonyl]‐2‐methylpiperazine), an inhibitor of protein kinase C and cyclic nucleotide‐dependent kinases, had no effect on sphingomyelinase and cholesterol ester formation. Thus the possibility of a modulation of cell sphingomyelin and cholesterol esters by a calmodulin‐dependent second messenger system must be considered.
Expression of the neu oncogene under the transcriptional control of the myelin basic protein gene in transgenic mice: Generation of transformed glial cells
Authors: Hayes C. , Kelly D. , Murayama S. , Komiyama A. , Suzuki K. , Popko B. 
Published: January 2005

AbstractWe have taken a transgenic approach in an effort to specifically transform oligodendrocytes, the myelinating glial cells of the central nervous system (CNS). Transgenic mice were generated with a DNA construct that contained the activated neu oncogene under the transcriptional control of the myelin basic protein (MBP) gene. The MBP/c‐neu transgenic animals have experienced a low incidence of brain tumors that express molecular markers specific to oligodendrocytes, providing a mouse model to study the formation and progression of oligodendrocyte tumors. A tumor from a transgenic animal has been dispersed in culture, and transformed cells that express properties of oligodendrocytes and astrocytes have been maintained. The degree to which these cells express phenotypic characteristics of oligodendrocytes or astrocytes is influenced by culture conditions. These transformed cells should serve as a valuable resource with which to study various molecular and biochemical aspects of the myelination process, as well as the lineage interrelationship of CNS glial cells.
Axons modulate the expression of proteolipid protein in the CNS
Authors: Scherer Steven S. , Vogelbacker H. H. , Kamholz J. 
Published: January 2005

AbstractWe examined the expression of mRNA encoding proteolipid protein (PLP), the major myelin protein in the CNS, in developing rat cerebrum, and in normal and degenerating optic nerves. PLP transcripts were initiated at two clusters of start sites that were separated by 30 base pairs. During the peak of PLP mRNA expression in developing cerebrum, a higher proportion of PLP transcripts were initiated from the destal start site, furthest from the open reading frame, than in mature cerebrum. We enucleated one eye of immature rats to cause Wallerian degeneration in the optic nerve. In these degenerating optic nerves, the steady state levels of PLP mRNA fell markedly, and the proportion of distally initiated PLP transcripts declined to the same proportion found in normal adult nerves. Changes in myelin gene expression were not limited to PLP mRNA, as the steady‐state levels of myelin basic protein (MBP) mRNA paralleled those of PLP mRNA in the developing cerebrum and in degenerating optic nerves. Thus, oligodendrocytes require axons to maintain their normal levels of PLP and MBP transcripts and the high proportion of distally initiated PLP transcripts that characterize early myelination. © 1992 Wiley‐Liss, Inc.
Cyclic AMP, but not basic FGF, increases the in vitro survival of mesencephalic dopaminergic neurons and protects them from MPP+‐induced degeneration
Authors: Hartikka J. , Staufenbiel M. , Lübbert H. 
Published: January 2005

AbstractWe studied how stimulation of protein kinase C and cAMP‐dependent protein kinases affect the development of mesencephalic dopaminergic neurons in primary cell cultures derived from fetal rats at embryonic day E14. The effects of compounds which activate these second messenger systems were compared to those of basic fibroblast growth factor (bFGF) and insulin‐like growth factor I (IGF‐I). In mesencephalic cultures, there was a continuous loss of dopaminergic neurons. Despite this decline in cell number, neurotransmitter uptake per neuron increased with time, indicating that the surviving dopaminergic neurons continued their biochemical differentiation while others degenerated. IGF‐I and bFGF did not affect the number of dopaminergic neurons. However, dopamine uptake per neuron was significantly higher in bFGF and IGF‐I treated cultures, suggesting that these factors stimulated differentiation. Protein kinase C and cAMP‐dependent protein kinases were not involved in mediating the effects of bFGF and IGF‐I. Treatment of cultures with phorbol esters did not affect dopamine uptake, whereas elevated levels of intracellular cAMP resulted in an increase in dopamine uptake which was additive to that elicited by bFGF or IGF‐I. Further analysis revealed that exposure of mesencephalic cultures to dibutyryl cAMP (dbcAMP) during the first 3 days after plating increased the survival of dopaminergic neurons, whereas prolonged treatment attenuated the development of the dopamine uptake system. Moreover, cyclic AMP, but not bFGF, was able to prevent the degeneration of dopaminergic neurons induced by 1‐methyl‐4‐phenyl‐pyridinium ion (MPP+), the active metabolite of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP). The results suggest that increased intracellular levels of cAMP protect dopaminergic neurons in situations of stress like the process of dissociation and plating or the exposure to neurotoxic compounds. Our results reveal novel possibilities for the treatment of Parkinson's disease. © 1992 Wiley‐Liss, Inc.
Immunohistochemical and biochemical analysis of N‐cadherin expression during CNS development
Authors: Lagunowich L. A. , Schneider J. C. , Chasen S. , Grunwald Gerald B. 
Published: January 2005

AbstractThe expression of the calcium‐dependent adhesion molecule N‐cadherin during chick embryo central nervous system (CNS) development was examined by immunohistochemistry and electrophoresis and immunoblotting. During histogenesis, N‐cadherin is expressed at high levels in a uniform fashion in many regions of the CNS. However, during later stages of development, expression becomes restricted to the ependymal cells lining the ventricular system and in the choroid plexus. This down‐regulation was confirmed by both immunohistochemical and biochemical techniques. The program of expression lags behind in the cerebellum in concert with the delayed development of this region of the brain. A high level of N‐cadherin was found to be expressed in the brainstem and spinal cord floorplate, while a low level was detected at the optic nerve head. The results indicate that while, in general, the program of N‐cadherin expression is similar in the retina and the brain, certain structures unique to the eye and brain express locally high or low levels of this adhesion protein. © 1992 Wiley‐Liss, Inc.
Effect of a discrete dorsal forebrain lesion in the rat on the expression of neuronal and glial‐specific genes: Induction of calmodulin, NF‐L, SC1, and GFAP mRNA
Authors: Landry C. F. , Ivy G. O. , Brown Ian R. 
Published: January 2005

AbstractThe influence of a localized tissue injury on the expression of genes encoding specific neuronal and glial proteins was examined using in situ hybridization. A pronounced induction of neuron‐specific calmodulin (CaM) mRNA was evident within cells proximal to the wound site by 2 hours following a cortical lesion in rats. By 12 hours postlesion, intense signal corresponding to CaM mRNA was found to extend 1 mm from the wound site. Changes in the expression of mRNA encoding two additional neuronal proteins, the 68 kilodalton neurofilament protein and the extracellular matrix protein, SC1, were also evident at 12 hours following the cortical injury. Of the two glial proteins examined, a dramatic elevation in levels of mRNA for glial fibrillary acidic protein (GEAP) was observed at the wound site by 12 hours postlesion. This intense labeling corresponding to GFAP mRNA was evident in the ipsilateral glial limitans and hippocampus as well as in the contralateral glial limitans. In contrast, the pattern of labeling for the β‐subunit of the S100 protein did not differ from that of control animals at either of the postlesion intervals examined. This study identifies four genes, CaM, GFAP, SC1, and NF‐L, which are induced following a localized cortical injury and which encode mRNA species enriched in specific cell‐types in the central nervous system. © 1992 Wiley‐Liss, Inc.
AP‐1 complex and c‐fos transcription are involved in TPA provoked and trans‐synaptic inductions of the tyrosine hydroxylase gene: Insights into long‐term regulatory mechanisms
Authors: Icard‐Liepkalns C. , Biguet N. Faucon , Vyas S. , Robert J. J. , Sassone‐Corsi P. , Mallet J. 
Published: January 2005

AbstractWe have previously shown that the phorbol ester, TPA, which activates protein kinase C, causes, in PC12 cells, a transcriptional activation of tyrosine hydroxylase (TH), the key enzyme in catecholamine synthesis. The study has now been extended to examine the processes that underlie this transcriptional stimulation and, in addition, to seek whether similar mechanisms are involved in long‐term trans‐synaptic induction of the TH gene in adrenal medullae of rats that have been given a single injection of reserpine.In both systems, it was found that the induction of c‐fos gene transcription was associated with that of the TH gene but with different kinetics. The promoter of the TH gene contains (at position −207/–200) a sequence (TGATTCA) which differs from the consensus TRE or AP‐1 site (TGACTCA) by one nucleotide. Experiments were carried out to investigate whether the AP‐1 protein complex which is known to contain Fos and Jun binds to the putative TRE region of the TH promoter. In the gel shift assays, the nuclear protein extracts derived from TPA‐treated PC12 cells and from AM of reserpine injected rats displayed a higher magnitude of binding to a 25‐mer TRE‐TH oligonucleotide as compared to controls. The results showed that the behaviour of TRE‐TH was atypical in that two retarded complexes (A and B) were observed, which were displaced by specific competitors. Trans‐activation experiments with plasmids TRE‐TH/TK/CAT and −754/–19 TH/pUC18‐CAT in PC12 cells showed an increase in CAT activity in response to TPA that correlates with the previously observed increase in TH transcriptional activity by TPA. Co‐transfection with plasmids BK28 containing c‐fos and/or with pSV‐c‐jun resulted in a significant increase in CAT activity showing a functional interaction of these proteins with TRE‐TH. Our findings indicate that the TRE‐TH site plays a critical role in trans‐synaptic regulation of the TH gene. © 1992 Wiley‐Liss, Inc.
Basic fibroblast growth factor in the hypoglossal system: Specific retrograde transport, trophic, and lesion‐related responses
Authors: Grothe Claudia , Unsicker K. 
Published: January 2005

AbstractTo further clarify the function of basic fibroblast growth factor (bFGF) in the nervous system, we have examined its distribution, lesion‐dependent regulation, retrograde transport, and trophic roles on rat hypoglossal neurons. In adult rats, bFGF‐like immunoreactivity is localized in hypoglossal motoneurons, drastically reduced 2 days after axotomy, and re‐expressed by 11 days. Neuron numbers and morphology assessed by Nissl staining are not affected by the lesion. 125J bFGF is specifically retrogradely transported by hypoglossal motoneurons from their peripheral nerve terminals. Moreover, bFGF stimulates the in vitro survival of hypoglossal neurons (ED50 2 ng/ml). In vivo administration of bFGF prevents lesion‐induced motoneuron death to 14% in 7 day old rats and to 60% in 18 day old rats, but not the axotomy‐induced decrease of choline acetyltransferase activity in the hypoglossal nucleus of adult rats. These results are consistent with a neurotrophic role of bFGF in the hypoglossal system. © 1992 Wiley‐Liss, Inc.
Two‐site enzyme immunoassay for βNGF applied to human patient sera
Authors: Lorigados L. , Söderström S. , Ebendal T. 
Published: January 2005

AbstractNerve growth factor (NGF) supports sympathetic and sensory neurons in the peripheral nervous system and serves functions in the development and maintenance of cholinergic neurons in the basal forebrain. NGF distribution can be studied with the use of a sensitive two‐site enzyme immunoassay (EIA). The monoclonal antibody 27/21 to mouse NGF was recently shown to effectively block the activity of both recombinant human NGF and native mouse NGF, and a two‐site EIA using monoclonal antibody 27/21 was optimized. We have now applied this assay to examine NGF levels in normal human serum and serum from Parkinson, Alzheimer, and Huntington patients. To further test the specificity of conjugate binding, dilutions of the human sera were preincubated with an excess of monoclonal NGF antibody 27/21 in solution. With this strategy it was possible to completely block the signal obtained using the two‐site EIA. Furthermore, we show that recombinant BDNF and NT‐3 do not cross‐react with monoclonal antibody 27/21 under our conditions. We found low levels of specific NGF immunoreactivity in normal human sera (0.4 ± 0.1 ng/ml). Significantly lower levels of NGF were found in sera from patients with Parkinson's and Huntington's disease whereas sera from Alzheimer patients showed only slight reductions in the NGF level. Two patients who had received intracerebral NGF infusions (one with Parkinson's and other with Alzheimer's disease) showed significantly elevated serum levels of NGF during the period of infusion. Due to an inhibitory activity in human serum, it was impossible to demonstrate the low levels of NGF activity in the human serum samples using explanted embryonic sympathetic ganglia, even after concentration by pressure dialysis. Thus, the serum levels are below the limit to evoke a response in NGF‐sensitive neurons and thus to expect any physiological effect. Nevertheless, the levels measured may be used as indicators in clinical conditions such as Parkinson's and Huntington's disease. © 1992 Wiley‐Liss, Inc.
Receptor neuron losses result in decreased cytochrome P‐450 immunoreactivity in associated non‐neuronal cells of mouse olfactory mucosa
Authors: Walters E. , Buchheit K. , Maruniak J. A. 
Published: January 2005

AbstractImmunohistochemical and immunoblot analyses were used to investigate nasal cytochrome P‐450 distribution in mice with either unilateral naris closure for 3, 4, or 5 months, or olfactory bulbectomy. P‐450 immunoreactivity was observed only in the supporting cells and Bowman's glands of the olfactory mucosa. Immunoreactivity was clearly reduced in rostral regions of the open‐side olfactory mucosa where losses of receptor neurons resulted from 3 to 5 months of closure. Closed‐side immunoreactivity was similar to controls. In 4 month closure animals that had regrown their receptor neurons, open‐side immunoreactivity was comparable to controls. Olfactory bulbectomy also depressed P‐450 immunoreactivity. These data suggest that presence or absence of receptor neurons markedly affects P‐450 expression in nonneuronal cells of the olfactory mucosa. © 1992 Wiley‐Liss, Inc.
Taurine allosterically modulates flunitrazepam binding to synaptic membranes
Authors: Quinn M. R. , Miller C. L. 
Published: January 2005

AbstractTaurine is hypothesized to exert its inhibitory neuromodulatory effects, in part, by interaction with the GABAA receptor. Although taurine displaces GABA agonist binding to synaptic membranes, its allosteric effects on the benzodiazepine recognition site of the GABAA receptor complex is unsettled. We determined the effects of taurine on [3H]flunitrazepam (Flu) binding to well‐washed, frozen‐thawed synaptic membranes prepared from rat cortex. Comparative binding studies were conducted at 37°C and on ice (0–4°C). At 37°C taurine increased Flu binding in a concentration dependent way by interaction with a bicuclulline sensitive site, similar to GABA. Taurine increased Flu binding by causing a decrease in KD. The maximal effectiveness of taurine on Flu binding could not be increased further by addition of GABA. In contrast, the maximal stimulation of Flu binding by GABA was decreased by addition of taurine to the level attained by taurine alone. These mixed agonist/antagonist effects of taurine are pharmacologically specific and qualify taurine as a partial GABA agonist in this type of allosteric interaction. However, taurine causes opposite effects on Flu binding when measured at 0–4°C: taurine interacts with a bicuculline insensitive site to inhibit Flu binding by increasing the KD. Taurine inhibition of Flu binding is not overcome by increasing concentrations of GABA. Although the mechanism of taurine inhibition of Flu binding at 0–4°C is unclear, it may be an indirect effect of taurine interaction with membrane phospholipids. More importantly, the results of these studies suggest that taurine, at physiologically relevant concentrations (EC50 = 100 μM) and temperature (37°C), may function as a partial GABA agonist in stimulating Flu binding to synaptic membranes. © 1992 Wiley‐Liss, Inc.
Gene structure and expression of the mouse 5‐HT2 receptor
Authors: Yang W. , Chen K. , Lan N. C. , Gallaher T. K. , Shih J. C. 
Published: January 2005

AbstractSerotonin (5‐Hydroxytryptamine, 5‐HT) is an important neurotransmitter which mediates numerous physiological functions. Using the SacI‐EcoRI restriction fragment of the rat brain 5‐HT2 receptor cDNA as a probe, we have screened a mouse brain cDNA library, created by random priming and constructed in SWAJ vectors, and have isolated a cDNA encoding a 1.4 kb open reading frame which codes for a functional mouse 5‐HT2 receptor identified from pharmacological binding profiles and coupling of phosphoinositide formation in a stably transfected fibroblast cell line. The deduced amino acid sequence is 97.4% identical to the rat 5‐HT2 receptor. Using the same 5‐HT2 receptor cDNA probe, ten positive genomic clones were isolated from two mouse genomic libraries constructed in the pWE15 cosmid vector and the EMBL‐3 phage vector. Extensive mapping and sequencing of these genomic clones indicate the mouse 5‐HT2 receptor coding region spans over 20 kb and is composed of three exons split by two introns. Northern blot analysis shows one band of 5–6 kb in the mouse brain, but not in the heart, lung, liver, or kidney total RNA. Southern analysis of mouse liver genomic DNA shows a simple pattern of digestion by several restriction enzymes, which suggests that one copy of the 5‐HT2 receptor gene may exist in the mouse genome. © Wiley‐Liss, Inc.
Effect of potassium and N‐methyl‐D‐aspartate on the aspartate aminotransferase activity in cultured cerebellar granule cells
Authors: Morán J. , Rivera‐Gaxiola M. 
Published: January 2005

AbstractThe effect of potassium depolarization and N‐methyl‐D‐aspartate (NMDA) on the activity of aspartate aminotransferase (AAT; EC 2.6.1.1), an enzyme suggested to be involved in neurotransmitter glutamate synthesis, was studied in cultured cerebellar granule neurons. Both KCl and NMDA increased AAT activity in a dose‐dependent manner. When cells were treated 48–72 hr with 40 mM KCl or 150 μM NMDA the AAT was enhanced about 65–75%. The EC50 for NMDA and KCl were 25 μM and 17 mM, respectively. The effect of NMDA and KCl was specific for AAT without affecting the activity of other enzymes like lactate dehydrogenase or protein content and it was observed only in granule cells but not in astrocytes or cortical neurons. The effect of KCl was not mediated by an activation of excitatory amino acid receptors and was Ca++‐dependent. The effect of NMDA was completely blocked by Mg++ and NMDA antagonists. The increase of AAT induced by AAT and KCl was blocked by cycloheximide and actinomycin D, suggesting an involvement of de novo synthesis of proteins and RNA. Kainic acid and quinolinic acid were also effective in increasing the AAT activity. The action of kainate was less effective than that of NMDA and it was observed only at relatively low concentrations (10 μM). Quinolinic acid raised the activity of AAT about 45% at a concentration of 500 μM. Other non‐NMDA agonists did not modify the AAT activity. From these findings we can conclude that NMDA and KCl exert a trophic action on cerebellar granular neurons. These conditions could be a simulation of the presynaptic activity required during development to induce survival and a biochemical differentiation, which we evaluated using AAT as a marker enzyme. © Wiley‐Liss, Inc.
Uptake and metabolism of malate in neurons and astrocytes in primary cultures
Authors: Hertz L. , Yu A. C. H. , Schousboe A. 
Published: January 2005

AbstractUptake and oxidative metabolism of [14C]malate as well as its incorporation into aspartate, glutamate, glutamine, and GABA were studied in cultured cerebral cortical neurons (GABAergic), cerebellar granule neurons (glutamatergic), and cerebral cortical astrocytes. All cell types exhibited high affinity uptake of malate (Km 10–85 μM) with slightly higher Vmax values in neurons (0.1–0.2 nmol × min−1 × mg−1) than in astrocytes (0.06 nmol × min−1 × mg−1). Malate was oxidatively metabolized in all three cell types with nominal rates of 14CO2 production of 2–15 pmol × min−1 × mg−1. The oxidation of malate was only slightly inhibited by 5 mM aminooxyacetic acid (AOAA). In granule cell preparations [14C]malate was incorporated into aspartate and glutamate and, to a much less extent, into glutamine. This incorporation was blocked by 5 mM AOAA. Astrocytes exhibited slightly higher incorporation rates into aspartate and glutamate, but in these cells glutamine was labelled to a considerable extent. AOAA (5 mM) inhibited the incorporation by 60–70%. In cultures of cerebral cortical neurons, very low levels of radioactivity derived from [14C]malate were found in aspartate and glutamate, and GABA was not labelled at all. Glutamine had the same specific activity as glutamate, indicating that the low rates of incorporation of radioactivity into amino acids in this preparation is likely to exclusively represent metabolism of malate in the small population of astrocytes (5% of total cell number), contaminating the neuronal cultures. The findings suggest that exogenous malate to a quantitatively limited extent may serve as a precursor for transmitter glutamate in glutamaterigc neurons. Astrocytes are able to metabolize malate to glutamate and related amino acids, but oxidize little malate to CO2. © Wiley‐Liss, Inc.