bluuebunny/crossref_metadata_2025_split huggingface dataset:
A brain synaptic dopamine‐binding protein: Isolation and partial characterization
Authors: Moroi K. , Hsu L. L. 
Published: January 2005

AbstractA dopamine‐binding protein (DABP) has been purified from the rat brain cortex to homogeneity. Solubilization of the DABP from the synaptosomal membranes (P2M) by cholic acid, subsequent agarose gel filtration of the cholic acid extract to separate phospholipids from the DABP, and lastly DA affinity chromatography successfully resulted in a purified DABP with approximately 0.006% yield in protein concentration and 0.03% yield in specific [3H]‐DA binding. The specific [3H]‐DA binding of the purified DABP was 117 fmol/mg protein/10 min with a 4.6‐fold purification compared with the whole homogenate. The purified DABP had an Rf value of 0.67 on native disk polyacrylamide gel and it gave one single polypeptide subunit on the SDS gel with an Rf value of 0.63. The apparent molecular weight of this single subunit was estimated to be 34.5 kilodaltons. The elution patterns from either DA‐ or ADTN‐affinity (2‐amino‐6, 7‐dihydroxy‐1,2,3,4‐tetrahydronaphthalene‐affinity) columns indicated that this DABP had higher affinity for DA agonists than for DA antagonists. Photoaffinity labeling of [3H]‐DA to this DABP in the P2M fraction and the specific [3H]‐DA to the purified DABP demonstrated a nanomolar range affinity corresponding to either D2 or D3 receptors. These data suggested that the purified DABP could be related to either D2 or D3 receptors in the brain.
Metabolism and function of gangliosides in developing neurons
Authors: Dreyfus H. , Ferret B. , Harth S. , Gorio A. , Durand M. , Freysz L. , Massarelli R. 
Published: January 2005

AbstractPrevious experiments have shown that the addition of a mixture of gangliosides to the growth medium induced morphological changes in primary neuronal cultures, producing especially a trophic effect and a sprouting of neurites (neuritogenesis). The study reported here examined the changes of some biochemical parameters that paralleled the morphological modifications of cultured neurons from chick brain hemispheres treated with gangliosides. Neurons cultured from 3 to 7 days in the presence of various concentrations of a purified mixture or of single‐species of gangliosides (GM1, GD1a, GT1b) revealed that these glycolipids were easily incorporated into the cells as a function of their exogenous concentrations. Incubation of neurons with N‐acetyl‐D‐[U‐14C]mannosamine showed a final labeling of all endogenous cellular and exogenous incorporated gangliosides; however, the radioactivity recovered decreased as a function of the number of sialic acid units of the exogenously added gangliosides. The treatment of neuronal cells from 3 to 7 days in culture with a mixture of 10−8 M and 10−5 M gangliosides led to the following observations on some neurochemical parameters: no effect on the influx of choline and dopamine; no effect on the spontaneous choline efflux, whereas the K+‐provoked one is abolished; decrease of the spontaneous and K+‐stimulated release of dopamine; no effect on the spontaneous release of GABA for 10−8 M gangliosides but an increase of both spontaneous and K+‐provoked release for 10−5 M gangliosides. The data suggest that the possible insertion of gangliosides into the neuronal membranes may imply structural modifications that may influence enzymatic activities, neurotransmitter transport, and finally, some nerve cell mechanisms.
Can functional reorganization of area 17 following monocular deprivation be modified by GM1 internal ester treatment?
Authors: Carmignoto G. , Canella R. , Bisti S. 
Published: January 2005

AbstractIt has been extensively reported that monocular exposure early in life leads to profound alterations in visual cortical areas, where the majority of cells become responsive only to the stimulation of the normal eye. We have investigated a possible effect of the monosialoganglioside internal ester, termed AGF2, on the neuronal cortical plasticity of the kitten's visual cortex following monocular deprivation. Results indicate that in monocularly deprived kittens treated with ganglioside the ocular dominance shift in favor of the normal eye is partially prevented.
Inhibition of brain tubulinyl‐tyrosine carboxypeptidase by endogenous proteins
Authors: Modesti N. M. , Argaraña C. E. , Barra H. S. , Caputto R. 
Published: January 2005

AbstractWhen a 25–50% ammonium‐sulphate‐insoluble fraction from a bovine brain preparation was chromatographed on a cellulose phosphate column, several protein fractions which inhibit the activity of tubulinyl‐tyrosine carboxypeptidase were obtained. One of these fractions exhibited activity of fructose‐bisphosphate aldolase (EC 4. 1. 2. 13) and the enzyme accounted for more than 95% of the protein of this fraction as judged by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis. The inhibitory activities of the two protein fractions which had the highest activity per mg of protein were practically abolished by pretreatment with pronase; preincubation with trypsin, on the other hand, caused only a partial inactivation of the inhibitors. The inhibitory activities were little affected by heating at 90°C for 5 min. Preincubation with purified tubulinyl‐tyrosine carboxypeptidase caused a great decrease of the inhibitory activities of these two fractions, leaving open the possibility that these inhibitors act as substrates of the carboxypeptidase.
Growth cones and the formation of central and peripheral neurites by sensory neurones in amphibian embryos
Authors: Roberts A. , Patton D. T. 
Published: January 2005

AbstractWe have examined the primary growth of neurites by Rohon‐Beard sensory neurones in embryos of Xenopus, Rana, and Ambystoma. Using transmission electron microscopy we have confirmed that some central longitudinal neurites first grow directly under the basal lamina which surrounds the spinal cord in Xenopus embryos. Using scanning electron microscopy of dissected embryos we have followed the growth of neurites from the spinal cord to their target tissue, the skin. Comparisons between the three genera are made and detailed observations on growth cones during fasciculation, on the somites and on the basal lamina of the skin are presented. The observations are discussed in relation to possible influences on the course of growth of the developing neurites.
Polyribosomes under developing spine synapses: Growth specializations of dendrites at sites of synaptogenesis
Authors: Steward O. , Falk P.M. 
Published: January 2005

AbstractWe have previously reported that there is a dramatic increase in polyribosomes associated with dendritic spines during periods of synapse growth induced by denervating lesions. We suggested that polyribosomes at the postsynaptic site may somehow be involved in the growth of synapses. To evaluate this hypothesis further, the present study determines whether synapses which are growing in the developmental period also have accumulations of polyribosomes. We examined the dentate gyrus of the developing rat electron microscopically at 7, 10, 15, 20, and 28 days of age, which spans the major period of synaptogenesis in this structure. Qualitative observations revealed dramatic accumulations of polyribosomes under spine synapses in the youngest animals (7 and 10 days of age). With synapse development, the accumulations of polyribosomes became less dramatic, so that by 28 days of age, the neuropil of the dentate gyrus appeared qualitatively mature. To determine the relationship between polyribosomes under spine synapses and synapse development, quantitative electron microscopic methods were use to evaluate synapse density (number of synapses/100 μm2), and the incidence of polyribosome‐containing spines (proportion of spine synapses with underlying polyribosomes) in the neuropil of the dorsal blade of the dentate gyrus at each age. An inverse relationship was found between synapse density and the proportion of spines with polyribosomes. Synapse density increased in an almost linear fashion between 7 and 28 days of age to levels which were actually somewhat higher than in mature rats, whereas the incidence of polyribosome‐containing spines was highest at the youngest ages and decreased with development. Thus, polyribosomes were most prominent under spine synapses during the period of maximal synapse growth. These results, together with our previous observations of increased numbers of polyribosomes under spines during lesion‐induced growth, suggest that the polyribosomes represent a structural specialization of dendrites at sites of synapse construction. We propose that they produce protein(s) that are involved in synapse growth.
Aromatic L‐amino acid decarboxylase, dopamine β‐hydroxylase, monoamine oxidase, malondialdehyde, and acid phosphatase in rat brain capillaries and kidney glomeruli in experimental hypertension
Authors: Valli V.V. , Sadasivudu B. 
Published: January 2005

AbstractSome metabolic consequences of experimental hypertension on rat brain capillaries and kidney glomeruli have been studied in rats made hypertensive by (a) a combination of deoxycorticosterone acetate injection and elevated salt intake (DOCA‐salt hypertension) and (b) isoproterenol injection. Enzyme activities were studied in vitro to ascertain directly or indirectly any changes in the metabolism of catecholamines and prostaglandins, and lysosomal integrity under conditions of experimental hypertension. Experimental hypertension was accompanied by an elevation in the activities of aromatic L‐aminoacid decarboxylase, dopamine β‐hydroxylase, and malondialdehyde concentration, both in the brain capillaries and kidney glomeruli of rats. On the other hand, monoamine oxidase activity increased in brain capillaries but decreased in kidney glomeruli. Acid phosphatase activity increased marginally in kidney glomeruli but decreased significantly in brain capillaries.The catecholamine‐synthesizing potential appears to have been augmented in both the tissue capillaries with a compensatory increase in the degrading enzyme activity in the brain capillaries of hypertensive rats. The absence of such an increase and an actual decrease in the monoamine oxidase activity in the kidney glomeruli may be responsible for the sustained maintenance of the hypertensive state. Increased malondialdehyde concentration may be due to the stimulation of the prostaglandin metabolism by the augmented catecholamine metabolism.
Metabolically derived aspartate–elevated extracellular levels in vivo in iodoacetate poisoning
Authors: Sandberg M. , Nyström B. , Hamberger A. 
Published: January 2005

AbstractGlycolysis was blocked in the hippocampus of the otherwise unaffected rabbit by perfusion of a previously implanted thin dialysis tube with a medium containing 0.1 mM iodoacetate. The perfusate from the dialysis tube was analyzed for free amino acids with liquid chromatographic separation of ortophthaldialdehyde derivatives. The data were used to calculate approximate levels of extracellular amino acids. Within 15 min after the beginning of iodoacetate perfusion, extracellular aspartate increased measurably, and the increase was tenfold within less than 2 hr. Although most other amino acids were unaffected, an elevation of taurine, phosphoethanolamine, and ethanolamine was observed with a delay of 30–40 min after the effect on aspartate.
Postnatal taurine deficiency in the kitten results in a persistence of the cerebellar external granule cell layer: Correction by taurine feeding
Authors: Sturman J.A. , Moretz R.C. , French J.H. , Wisniewski H.M. 
Published: January 2005

AbstractDietary deprivation of taurine in pregnant cats from approximately 1 week prior to giving birth is sufficient to reduce substantially the taurine concentration in feline milk but does not result in any abnormalities in kittens at birth. Kittens nursing on this low taurine milk have a lower growth rate than normal, have lower tissue taurine concentrations, and 8 weeks after birth have a persistence of cells in the cerebellar external granule cell layer. Mitotic figures are present also, indicating that cell division is occurring still, an event which normally is completed 3–4 weeks after birth. Daily oral supplementation with 40 μmoles taurine increases the growth rate almost to the level of normally nurtured kittens and results in normal tissue taurine concentrations and apparently normal migration of cells in the cerebellum. These findings indicate that nutritional taurine supplied in the milk is involved in the normal ontogeny of the cerebellum and that a taurine deficiency at this stage of development results in a maturational delay.
Ganglioside patterns during cerebral development in the normal and reeler mouse
Authors: Irwin L.N. , Hunter G.D. , Crandall J.E. , McCluer R.H. 
Published: January 2005

AbstractGangliosides were extracted from cerebral tissue of reeler and normal mice, and analyzed by two‐dimensional thin‐layer chromatography at embryonic and postnatal ages. The ganglioside pattern changed substantially as development proceeded in the telencephalon of both reeler and normal mice, but was the same at any given age for both conditions, despite the marked histological differences between reeler and normal samples. These results indicate that abnormal ganglioside patterns do not result from the reeler mutation at early stages of brain development, and that the cell misalignment characteristic of the reeler phenotype involves molecules other than gangliosides.
Thoracic dorsal funicular lesions affect the bouton patterns on, and diameters of, layer VB pyramidal cell somata in rat hindlimb cortex
Authors: Ganchrow D. , Bernstein J. J. 
Published: January 2005

AbstractThe effect of spinal dorsal funicular lesions (T 12) upon the frequency of boutons on, and diameters of the somata of pyramidal cells in layer VB of hindlimb cortex was studied. Adult rats sustained bilateral damage to either the dorsal column (DC, n = 10) alone or DC combined with the corticospinal tract (CS) (DC+CS, n = 34) and were utilized 1, 2, 3, 7, 14, 30, 45, 60, 90, or 120 days postoperatively (DPO). Neurons randomly sampled from 44 lesioned and 13 unoperated cases were analyzed for the number of silver‐impregnated boutons (Rasmussen method) on the circumference of the soma as well as diameters of the soma, nucleus, and nucleolus. Analyses of variance comparing across lesioned and normal groups were significant for bouton counts on the soma (P < 0.01), and diameters (long axis) of somata (P < 0.01) and their nuclei (P < 0.05). Both lesioned groups exhibited significant decreases from normal for these latter three parameters. With respect to survival time for the DC+CS‐lesioned animals we noted the following: (1) Bouton counts on the soma significantly decreased below normal between 1 and 60 DPO; this decrease was most dramatic during the first three days postlesion. (2) Somal diameter (long axis) significantly decreased below normal between 2 and 120 DPO (except at 14 and 90 DPO). (3) Nuclear diameter (long axis) significantly decreased below normal only at 90 DPO. (4) Bouton counts on somata of neurons in layers VB and IV [Ganchrow and Bernstein, 1981] of hindlimb cortex correlated negatively and significantly across 120 postlesion days. The rapid shrinkage and reduced afferentation of layer VB somata during the first week following DC+CS lesions suggest initial, retrograde reactions to CS axotomy. Since bouton counts on layer VB somata were significantly less (P < 0.05) in DC‐ than DC+CS‐lesioned rats, it is hypothesized that CS axotomy regulated a set‐point for increased afferentation which was maintained on the shrunken somata between 7 and 120 DPO.
Reactions of the geniculate cells to extraocular proprioceptive activation in rabbits
Authors: Molotchnikoff S. , Casanova C. 
Published: January 2005

AbstractThe aim of these investigations was to advance our knowledge of the influence of extrinsic ocular muscle (EOM) stretching on cell excitability of the retinocortical pathway. The initial goal was the lateral geniculate; however, histologic analysis indicated that most cells that responded to stretching were located near its superior edge, in an area analogous to the perigeniculate. Rabits were anaesthetized and prepared for single‐cell recordings. The extraocular muscles were detached from the eye and attached to a rigid tungsten hook. The hook was soldered to the pivot of a galvanometer that was controlled by a waveform generator. Precise and repeated length changes were obtained with extension and relaxation ramps of constant velocity. Thirty percent of the unit (N = 250) responded to EOM stretching. These stimuli evoked either an excitation or a decrease of the units' spontaneous activity. Several experimental controls provided evidence that the signals that evoked the geniculate responses originated from proprioceptors belonging to the EOM. Most responding cells had their receptive fields located eccentrically (≥50°). Also, cells that reacted to EOM stretching responded to optic nerve stimulation with a significantly shorter latency than cells that were unresponsive. Pairing the EOM stretching with light stimuli produced the following results. In about half of the units the light‐evoked responses augmentded, but in 28% of the cells the light‐evoked discharges decreased. These effects were obtained even though EOM stretching delivered singly failed to elicit a reaction from the cell. Histologic reconstructions indicated that cells were distribution in a discrete region lying rostral and dorsomedial to the lateral geniculate nucleus. This area has been associated with the perigeniculate nucleus in cats and rats.
Substrate oxidation by isolated rat brain mitochondria and synaptosomes
Authors: Tildon J. T. , Roeder L. M. , Stevenson J. H. 
Published: January 2005

AbstractThe rates of [6‐14C]‐glucose oxidation by reconstituted systems of cytosol and mitochondria or cytosol and synaptosomes were essentially the same as the rate of oxidation of [3‐14C]‐3‐hydroxybutyrate. However, the rate of [U‐14C]‐glutamine oxidation by mitochondria was 2.5 times that by synaptosomes. The addition of glutamine (5 mM) caused a reduction in the rates of oxidation of [6‐14C]‐glucose of 20% and 40% by mitochondria and synaptosomes, respectively. Conversely, the addition of glucose (5 mM) had little or no effect on the rate of [U‐14C]‐glutamine oxidation by either organelle. Amino‐oxyacetate decreased [U‐14C]‐glutamine oxidation by mitochondria more than 35% but had little or no effect on the rate of glutamine oxidation by synaptosomes. When glucose (5 mM) was added to [3‐14C]‐3‐hydroxybutyrate, the rates of oxidation by the mitochondria and synaptosomes were increased by 65% and 77%, respectively. However, in the reverse situation the addition of 3‐hydroxybutyrate decreased [6‐14C]‐glucose oxidation by synaptosomes (35%) but did not decrease the rate by mitochondria. These results suggest that differences in the rates of substrate utilization by mitochondria and synaptosomes and differences in substrate interactions in these two subcellular organelles may contribute to metabolic compartmentation in the brain.
Selected nutrients reduce the pyruvate requirement for survival in vitro of chick central nervous system neurons
Authors: Facci L. , Skaper S. D. , Varon S. 
Published: January 2005

AbstractCentral nervous system neurons, cultured as monolayers at low density, need exogenous pyruvate for their survival. The pyruvate concentrations required by embryonic day 8 (E8) chick forebrain neurons are reduced substantially by other low molecular weight agents present in Dulbecco's modified Eagle's medium (DMEM) and in astroglia‐conditioned Eagle's basal medium (EBM). To examine the nature of these pyruvate‐sparing molecules, E8 chick forebrain neurons were cultured in EBM containing a concentration of pyruvate too low to support neuronal survival, unless sparing agents were supplied. This stragegy permitted the identification of the pyruvate‐sparing DMEM constituents, omission of which had led to neuronal loss. Pyruvate sparing required a mixture of (i) serine, (ii) pyrioxal (or riboflavin and biotin), and (iii) six essential amino acids: arginine, cystine, leucine, isoleucine, tyrosine, and tryptophan (each replaceable by corresponding amino acids, except tryptophan). All pyruvate‐sparing contributors were optimally needed at or near their DMEM concentrations.
Coexistence of high‐affinity uptake mechanisms for putative neurotransmitter molecules in chick embryo retinal neurons in purified culture
Authors: Pessin M. , Adler R. 
Published: January 2005

AbstractWe report here that high‐affinity uptake mechanisms for two or three putative neurotransmitter molecules coexist in many of the neurons present in glia‐free, purified neuronal monlayers from chick embryo retina. Replicate cultures were incubated with the tritiated forms of the amino acids gamma‐aminobutyric acid (GABA), taurine (TAU) and aspartate (ASP) either individually or in binary or in binary or tertiary combinations. Incubation conditions were those typically used to analyze high‐affinity uptake mechanisms. At the end of the incubation period the cultures were either lysed in water for measurement of intracellular radioactivity by liquid scintillation counting, or fixed in glutaraldehyde and prepared for autoradiography. Our results indicate that there is coexistence of uptake mechanisms for putative neurotransmitters in retinal cells. Biochemical measurements showed that, at the concentrations used in these experiments, two or more radioactive amino acids could be taken up simultaneously by the cultured populations without extensive inhibition. Moreover, the percentage of cells that appeared autoradiographically labeled in cultures exposed to two or more radioactive amino acids was less than the sum of the percentages of labeled cells when each amino acid was applied individually. Numerical analysis of the autoradiographs was carried out to determine the percentage of cells that coul take up only one, only two, or the three putative amino acid neurotransmitters under investigation. This analysis showed that approximately 20% of the neurons have only the mechanism for TAU, whereas very few if any neurons have high‐affinity uptake mechanisms for GABA alone or ASP alone. Our experiments have identified populations of cells that take up GABA and TAU (but not ASP) or ASP and TAU (but not GABA). Interestingly, we have not seen any neurons that can take up ASP and GABA and cannot take up TAU, although as many as 50% of the neurons can take up ASP, GABA, and TAU simultaneously. By showing simultaneous uptake of different putative neurotransmitters within individual neurons, our results emphasize the concept that the presence in a given neuron of a high‐affinity mechanism for a particular molecule is not a sufficient criterion to assign a neurotransmitter function to that molecule in that neuron.
Transplantaion of embryonic chick spinal cord into transection adult chicken into transection adult chicken spinal cords: A useful model for transplantation research
Authors: Grady M. S. , Steward O. , Jane J. A. 
Published: January 2005

AbstractAdult chicken spinal cords were completely transected under direct visualization. One week later, embryonic chick spinal cords 6 days, 9 days, or 11 days old were implanted into the site of transection. The animals were allowed to survive for 2 months and then killed and the spinal cords were prepared for histologic analysis. The survival and outgrowth of the embryonic transplants were compared with regard to the age of the implant, and its effects on the host tissue. Six‐day embryonic tissue survival and integrated far better than 9‐day or 11‐day, and adult spinal cord subjacent to the early age embryo showed fewer degenerative changes. The chick embryo may provide a model for use in CNS transplantation.