bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence that the axolemmal mitogen for cultured schwann cells is a positively charged, heparan sulfate proteoglycan‐bound, heparin‐displaceable molecule
Authors: Decoster M. A. , Devries G. H. 
Published: January 2005

AbstractTreatment of axolemma with pH 9 buffer results in a pellet enriched two‐fold in the mitogen for cultured Schwann cells. Heparitinase treatment releases 8% of the mitogen into solution, while heparin selectively solubilizes the mitogen, resulting in an extract which has a specific mitogenic activity approximately 2.5 times greater than the mitogenicity of the starting axolemma membrane. These data support a model in which the axolemmal mitogen is a positively charged molecule associated with negatively charged sulfated proteoglycans.
Cytological and cytochemical (RNA) studies on rubral neurons after unilateral rubrospinal tractotomy: The impact of GM1 ganglioside administration
Authors: Barron K. D. , Banerjee M. , Dentinger M. P. , Scheibly M. E. , Mankes R. 
Published: January 2005

AbstractThe rubrospinal tract (RST) was cut unilaterally at C2–3 segment in 21 rats that were killed 3, 7, 10, 14, 28, 60, and 90 days later. Additionally, 14 rats, killed 14 or 28 days after lesioning, were treated postoperatively by daily intraperitoneal injections of GM1 ganglioside. Six unoperated, untreated rats served as controls. In untreated animals, axotomized neurons of the magnocellular division of the red nucleus (RN) exhibited cytoplasmic, nuclear, and nucleolar atrophy 7–10 days postoperatively. Atrophy progressed through the 90th postoperative day. Regression analyses disclosed a bimodal pattern to cytoplasmic and nucleolar atrophy, with an initial rapid phase changing to a slower but progressive mode from 14 days postoperatively. Nuclear atrophy proceeded in a unimodal manner. GM1 treatment did not affect these atrophic processes. Neuronal loss did not occur in the axotomized RN through the 60th postoperative day. Axotomized neurons of untreated rats showed significant and progressive reductions in mean somal (cytoplasmic) and nucleolar RNA from, respectively, the 7th and 14th postoperative day. GM1 partly prevented these RNA losses. Both in treated and untreated rats, spinal cord lesions contained many axonal sprouts 2 to 4 weeks after surgery, but newly generated axons did not traverse the rostro‐caudal extent of any lesion.
Consensus residues at the acetylcholine binding site of cholinergic proteins
Authors: Peterson G. L. 
Published: January 2005

AbstractThe nicotinic (nAcChR) and muscarinic (mAcCh) acetylcholine receptors and acetylcholinesterase (AcChEase) are structurally unrelated but share a common functional property: interaction with acetylcholine (AcCh). Alignment of the probable AcCh binding site regions of the nAcChR and mAcChR protein sequences revealed the presence of ten nearly identically spaced consensus residues, six of which contain potentially ligand‐interactive side chains. Important elements of the consensus residues also were found in one unique sequence region of the AcChEases. Alignments among the two receptors and AcChEase outside the apparent binding region were rare, and the consensus AcCh binding residues were largely substituted in the homologous proteins, which do not bind AcCh. The consensus residues include two possible anionic subsite Asp residues and a Ser that may hydrogen bond to the AcCh carbonyl in the receptors. These residues correspond to positions Asp‐166, Ser‐173, and Asp‐200 in the neuromuscular nAc‐ChR; Asp‐71, Ser‐78, and Asp‐105 in the M1 mAcChR; and Asp‐93 and Asp‐128 in Torpedo AcChEase. No corresponding consensus Ser is found in the AcChEase sequence; this is expected because of a downstream esterase active‐site Ser‐200 (Torpedo). A receptor‐conserved and disulfide‐linked Cys corresponding to neuromuscular nAcChR residue 193 and M1 mAcChR residue 97 may be important in energy transduction associated with agonist‐mediated events. The presence of additional binding‐site aromatic residues that may form a hydrophobic environment near the anionic subsite are aligned within, but not between, the three cholinergic protein groups. These observations target specific regions and residues within these proteins for structure‐function studies of the cholinergic binding domain.
Effects of free fatty acids and acyl‐coenzyme a on diacylglycerol kinase in rat brain
Authors: Kelleher J. A. , Sun G. Y. 
Published: January 2005

AbstractOur earlier studies have indicated the presence of diacylglycerol kinase activity in rat brain cytosol as well as subcellular membrane fractions (Strosznajder et al.: Neurochemistry International 8(2):213–221, 1986). There is much evidence indicating the release of dincylglycerols due to stimulation of polyphosphoinositide hydrolysis by hormones and receptor agonists. In turn, diacylglycerols have been linked to a second messenger role for activation of protein kinase C. The present study tests the ability of free fatty acids and acyl‐coenzyme A (acyl‐CoA) to regulate diacylglycerol kinase activity. In a system containing brain cytosol and microsomes, addition of oleic acid (0.5 mM) resulted in large stimulation of diacylglycerol kinase activity as well as some translocation of the enzyme from cytosol to microsomes. On the other hand, oleoyl‐CoA (0.1 mM), but neither palmitoyl‐CoA nor arachidonoyl‐CoA, was effective in translocation of the diacylglycerol kinase. Unlike oleic acid, which preferred to associate with membranes, most of the oleoyl‐CoA remained in the cytosolic fraction. Since free fatty acids in brain are stringently controlled and are released during ischemic insult, a condition which also elicits the breakdown of polyphosphoinositide to diacylglycerols, results here suggest a plausible mechanism for regulation of diacylglycerol metabolism by free fatty acids and acyl‐CoA.
Different classes of cat spinal neurons display differential sensitivity to sodium pentobarbital
Authors: Paik K. S. , Nam S. C. , Chung J. M. 
Published: January 2005

AbstractThe effect of graded doses of systemically injected sodium pentobarbital on several classes of spinal neurons was studied using spinal cats. Classes of spinal neurons included unidentified dorsal horn cells, ascending tract dorsal horn cells, and motoneurons. Single unit activity of spinal neurons was evoked by electrically stimulating a peripheral nerve with an intensity strong enough to excite both A and C fibers. The A‐ and C‐fiber evoked activity was compared before and after intravenous injections of small incremental doses of sodium pentobarbital. The activity of different classes of spinal neurons showed different sensitivities to graded doses of systemically injected pentobarbital. The reflex activity of motoneurons elicited by stimulation of peripheral nerve was much more sensitive to pentobarbital than that of dorsal horn cells. In general, activity evoked by peripheral unmyelinated fibers was more susceptible to pentobarbital than was that evoked by myelinated fibers. However, intravenous injections of pentobarbital produced nondifferential suppression of dorsal horn cell activity evoked by noxious and innocuous mechanical stimuli applied to the peripheral receptive fields.
On the GABAA receptor: A molecular modeling approach
Authors: Aprison M. H. , Lipkowitz K. B. 
Published: January 2005

AbstractBicuculline methobromide, a complex alkaloid, antagonizes in some unknown manner the action of GABA, an important inhibitory transmitter in the CNS. To help understand the mechanism of this antagonism we have employed molecular modeling techniques to assess the similarity and difference between this antagonist and GABA plus four direct GABA agonists. Topological and electronic charge congruence between these five molecules was examined in great detail. It was found that each of the five molecules has three clearly defined atoms that serve as attachment points at the GABAA receptor site. It is hypothesized that an additional negatively charged atom on bicuculline serves as an additional point of attachment that blocks the nearby chloride ion channel. The model presented offers an explanation of why muscimol acts as a better agonist than GABA as well as rationalizing why (+)‐bicuculline acts as an antagonist but (−)‐bicuculline does not.
Ganglioside and lipid composition of bulk‐isolated rat and bovine oligodendroglia
Authors: Yu R. K. , Macala L. J. , Farooq M. , Sbaschnig‐Agler M. , Norton W. T. , Ledeen R. W. 
Published: January 2005

AbstractWe have examined the ganglioside composition of 30‐day and 60‐day postnatal rat oligodendroglia, adult bovine oligodendroglia, gray matter, white matter, and myelin and also the total lipid composition of the oligodendroglial preparations. The ganglioside patterns of rat and bovine oligodendroglia, as previously found for human oligodendroglia, were more complex than those of myelin. These data indicate that oligodendroglial perikarya can synthesize many brain type gangliosides, not all of which are incorporated into the compact myelin. Alternatively, the ganglioside composition of myelin may be altered in situ by the myelin‐associated neuraminidase. In these two species, as in human, GM4 appears specific to oligodendroglia and myelin, while GD3 and GM3 are enriched in oligodendroglia but not myelin. In bovine oligodendrocytes GD3 is the major ganglioside. The total lipid concentration, as well as the percentage of cholesterol, sphingomyelin, phosphatidylinositol, and phosphatidylserine, differ for 30‐ and 60‐day‐old rat oligodendroglia and may be developmentally correlated with changes in myelin composition during myelinogenesis. There are also marked differences in the lipid composition of bovine oligodendroglia compared to rat oligodendroglia, with the former having more galactolipid and less ethanolamine phosphoglycerides.
Implantation of rabbit embryo brain fragments into newborn mice: Integration and survival of xenogeneic astrocytes
Authors: Suard I. M. , Collins V. P. , Ignacio V. , Jacque C. M. 
Published: January 2005

AbstractBrain fragments containing embryonic rabbit glia were implanted into the brains of newborn mice. The hosts developed an astroglial reaction around the transplants and along the needle tracks. Transplantderived astrocytes were identified in the operated brain by their expression of rabbit GFAP. During the first few days post‐implantation (PI) glial cells were exchanged between the transplant and the host. Less than 3 to 5 days PI, the transplant was extensively invaded by host astrocytes. Xenogeneic astroglial cells were first detected 10 days PI in the immediate proximity of the transplant. At 2 to 11 weeks, they could be detected either close to or at distance from the point of implantation. Most often, transplant‐derived astrocytes presented a morphology similar to that of neighboring host astrocytes. Xenogeneic glial cells were found to participate in various types of astroglial features: sub‐pial, pericapillary, fibrous, and protoplasmic. This morphological integration suggests that they are physiologically integrated, at least to a certain degree, in the host tissue.In spite of their integration into the host, xenogeneic astrocytes disappear after 3 months without signs of an inflammatory reaction.
Modulation of pp60c‐src tyrosine kinase activity during secretion in stimulated bovine adrenal chromaffin cells
Authors: Oddie K. M. , Litz J. S. , Balserak J. C. , Payne D. M. , Creutz C. E. , Parson S. J. 
Published: January 2005

AbstractHigh levels of the proto‐oncogene product, pp60c−src, have been found in developing and adult neural tissues as well as in certain fully mature cells of the hematopoietic lineage, e.g., platelets and myelomonocytes. Adrenal medullary chromaffin cells exhibit characteristics of both types of cells, i.e., they are derived from the neural crest and carry out exocytosis in response to specific stimuli. Earlier studies have shown that pp60c‐src localizes not only to the plasma membrane of chromaffin cells but also to the membranes of chromaffin granules, the secretory vesicles of these cells that store catecholamines and other secretory products. To investigate the possible involvement of pp60c‐src in exocytosis, cultured bovine chromaffin cells were analyzed for changes in c‐src tyrosine kinase activity in response to stimulation by several secretagogues. Results of in‐vitro immune complex kinase assays showed that pp60c‐src, derived from cells that had been stimulated for various lengths of time, exhibited decreased auto‐ and transphosphorylating activities as compared to pp60c‐src immunoprecipitated from control cells. The greatest reduction in activity was observed 10 min post‐stimulation, while normal levels were regained 2–6 hr after secretagogue treatment. Western immunoblot analysis of the immunoprecipitated pp60c‐src revealed that approximately 50% less c‐src protein was present in immune complexes prepared 10 min after stimulation as compared to those prepared from mock‐stimulated controls, resulting in a specific autophosphorylating activity that was 42–47% of control and little or no reduction in the transphosphorylating specific activity. In experiments in which the rate of secretion of [3H]‐norepinephrine from cells preloaded with this compound was compared to the rate of modulation of pp60c‐src activity, 50% of the maximal reduction in pp60c‐src activity occurred within 2–4 min while 50% maximal release of [3H]‐norephinephrine occurred within 1–3 min. Taken together, these results suggest that pp60c‐src may play some role (direct or indirect) in the exocytotic process.
Impact of the genetic background of transgenic mice upon the formation and timing of choroid plexus papillomas
Authors: Cho H. J. , Seiberg M. , Georgoff I. , Teresky A. K. , Marks J. R. , Levine A. J. 
Published: January 2005

AbstractTransgenic mice harboring the SV40 large T antigen gene in a C57Bl/6J genetic background (SV11) first express this gene at 1–2 weeks of age, develop papillomas of the choroid plexus by 80–90 days, and die within 125 days after birth. Transgenic mice harboring the same transgene in a (SV11‐C57Bl/6J × NZW/lacJ) F1 genetic background express considerably lower levels of the transgene mRNA at comparable times after birth. As a consequence, tumor development and death are delayed. The NZW mice appear to contribute a dominant negative regulator for the expression of the SV40 large T antigen transgene, which in turn has a dramatic effect upon the time of appearance of tumors and the death of these transgenic animals.
Secretion of nerve growth factor in cultures of glial cells and neurons derived from different regions of the mouse brain
Authors: Houlgatte R. , Mallat M. , Brachet P. , Prochiantz A. 
Published: January 2005

AbstractThe regional ability of central neurons and glial cells to produce nerve growth factor (NGF) was studied in vitro. NGF secretion was compared in cultures of perinatal astrocytes or embryonic neurons that were derived from various mouse brain structures. No regional differences were detected among cultures of post‐natal day 2 glial cells of hippocampal, cortical, striatal, or mesencephalic origin. In all cases, levels of NGF released by the cells were very similar. They were closely correlated to the growth rate as shown by the fact that exponentially growing cells produced relatively more factor than did confluent cells, a finding in agreement with previous observations. Unlike growth‐phase cells, primary astrocytes immediately plated at high cell density did not secrete any assayable factor before the 7th day of culture. Levels of NGF found during the following days remained low. In contrast, striking differences were observed among cultures of embryonic neurons. NGF was found in relatively large amounts in cultures of embryonic day 17 or 19 striatal neurons, whereas media conditioned by neurons from the mesencephalon, cortex, or septum contained much less factor. Amounts of NGF assayed in cultures of hippocampal neurons varied with the time of sampling of this brain structure. Levels of factor were significantly higher in media conditioned by embryonic day 19 neurons than in media of embryonic day 17 neurons. However, amounts of NGF found in supernatants of hippocampal neurons remained smaller than those present in cultures of striatal nerve cells. Altogether, the results suggest that, in addition to astrocytes, central neurons may also synthesize and secrete NGF in vitro and that this phenomenum is dependent on both the origin and the developmental stage of the neuronal population.
Organization of oligodendroglial membrane sheets: II. Galactocerebroside: Antibody interactions signal changes in cytoskeleton and myelin basic protein
Authors: Dyer C. A. , Benjamins J. A. 
Published: January 2005

AbstractAntibodies to galactocerebroside (GalC) cause patching of this surface glycolipid over internal domains of myelin basic protein (MBP), which are demarcated by a network of microtubules. The patching occurs whether or not second antibody is present, but the process is accelerated by the presence of second antibody. GalC patching results in disruption of microtubules in the lacy networks in oligodendroglial membrane sheets and in the eventual fusion of MBP domains, similar to the effects of colchicine (Dyer and Benjamins, 1989). Antibodies to GalC also disrupt F‐actin in the lacy networks. Since colchicine does not alter the distribution of F‐actin, anti‐GalC is causing F‐actin redistribution by a mechanism other than microtubule depolymerization. Extended exposure to anti‐GalC results in coalescence of surface GalC patches concomitant with fusion of internal MBP domains. When anti‐GalC is applied to induce GalC patching in cells previously treated with cytoskeletal inhibitors, patching is altered. After colchicine treatment, GalC surface staining is granular; i.e., patching is totally disorganized. Following cytochalasin B treatment, most membrane sheets display a few very large patches rather than the normal multiple, small patches. These GalC surface patterns are similar to the MBP distributions following the respective drug treatments (Dyer and Benjamins, 1989). Thus, the pattern of GalC distribution in the presence of antibody always reflects the organization of the underlying MBP domains; in turn, the organization of the MBP domains is determined by the lacy networks of microtubules in the oligodendroglial membrane sheets.
Effect of huperzine A, a new cholinesterase inhibitor, on the central cholinergic system of the rat
Authors: Tang X.‐C. , De Sarno P. , Sugaya K. , Giacobini E. 
Published: January 2005

AbstractThe present study represents the first comprehensive investigation of the effect of huperzine A (HUP‐A), a new cholinesterase inhibitor (ChEI) isolated from a Lycopodium species, upon acetylcholinesterase (AChE) activity, acetylcholine (ACh) levels and release, and cholinergic receptors in rat brain following acute i.m. or i.p. administration. The study shows that HUP‐A can produce a long‐term inhibition of AChE activity in brain (up to 360 min) and an increase in the ACh levels up to 40% at 60 min. There is considerable regional variation in the degree of ACh elevation after HUP‐A with maximal values seen in frontal (125%) and parietal (105%) cortex and smaller increases (22–65%) in other brain regions. HUP‐A at concentrations of 10−6 to 10−4 M does not significantly alter the electrically evoked release of 3H‐ACh from cortical slices. With the exception of the highest concentrations (6 × 10−4 M) the displacement effect of HUP‐A for cholinergic ligands is stronger for 3H‐(−)nicotine than for 3H‐QNB. A parallel autoradiographic study in the mouse shows that 60 min after i.v. injection (183 μg/kg) the drug is present in all brain regions, but it is particularly concentrated in certain areas such as frontoparietal cortex, nucleus accumbens, hippocampal, and striatal cortex. Radioactivity is practically absent in the whole body at 12 hr. Our study suggests that this new ChEI has interesting cholinomimetic properties, and its effects satisfy more closely established criteria for an ideal ChEI for therapeutic use than previously tested compounds.
Cholinergic agonists selectively induce proliferative responses in the mature subpopulation of murine thymocytes
Authors: Rossi A. , Tria M. A. , Baschieri S. , Doria G. , Frasca D. 
Published: January 2005

AbstractThe incubation of murine thymocytes for 24 hr in the presence of cholinergic agonists induces selective proliferation of PNA− cells as measured by thymidine incorporation.The response of PNA− cells is mediated by the activation of nicotinic receptors. This conclusion is suggested by the inability of the muscarinic agonist, oxotremorine, to induce cell proliferation and by the inhibition exerted by the nicotinic antagonist, d‐tubocurarine.The presence of cholinergic axons in the murine thymus adds biological interest to the selective expression of functional cholinergic receptors on mature thymocytes.
Intracerebral transplantation of dissociated central nervous system tissue suspensions: Use of phaseolus vulgaris leucoagglutinin as a cell marker
Authors: Shigematsu K. , Kamo H. , Akiguchi I. , Kimura H. 
Published: January 2005

AbstractSuccessfully transplanted neurons and their sprouting processes were demonstrated by Phaseolus vulgaris leucoagglutinin (PHA) marking. PHA is transported anterogradely and readily reveals the post‐transplantation growth of the neuronal processes. Suspensions of fetal central nervous tissue, prepared by dissociation of embryonic rat brain, were marked with PHA and then transplanted into the striatum of nonimmunosuppressed young adult rats. At various intervals thereafter (1 day, 2 days, 1 week, 2 weeks, 1 month, and 2 months), the animals were sacrificed for histological examination with PHA and tyrosine hydroxylase (TH) immunohistochemistry. Up to 2 weeks after transplantation, PHA immunohistochemistry was capable of demonstrating grafted neurons and their presumably regenerated neuronal processes. However, at periods 1 month or longer after transplantation, PHA immunohistochemistry was unreliable. Thus, the PHA marking method has limitations in terms of its retention period, when applied to the intracerebral transplantation of dissociated cell suspensions. Nevertheless, the method presented here can be utilized to study neuronal regeneration as well as the relationship between transplanted neurons and the host tissue.
Developmental profile of glutamine synthetase in lines of mice bred for ethanol sensitivity
Authors: Sakellaridis N. , Mangoura D. , Masserrano J. M. , Detsis V. , Leoni C. J. , Deitrich R. , Vernadakis A. 
Published: January 2005

AbstractGlutamine synthetase (GS) activity was used as a marker to examine differences in astrocyte development in mice selectively bred for ethanol sensitivity: long sleep (LS), short sleep (SS), mild ethanol withdrawal (MEW), severe ethanol withdrawal (SEW) and control ethanol withdrawal (CEW). We found that (1) GS activity in MEW and SEW was higher than in LS and SS during the first 2 weeks of postnatal development, in the forebrain but not in the cerebellum; (2) lower GS activity was observed consistently in all areas examined with the SS mice as compared to the LS; (3) glutamine synthetase activity in MEW and SEW differed significantly from their controls (CEW) during the early developmental period regardless of the brain region examined; however, after 30 days of maturation, GS activity in SEW was higher than that in MEW and CEW in the forebrain. Astrocytes are known to contribute in the regulation of the neuronal microenvironment. Therefore, we interpret the differences we found in astrocytic function during early brain development among these lines of mice to account in part for the neuronal predisposition to ethanol sensitivity.