bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of lipids in mouse brain cell cultures during development
Authors: Siegrist Hans Peter , Bologa‐Sandru Liane , Burkart Thomas , Wiesmann Ulrich , Hofmann Karel , Herschkowitz Norbert 
Published: January 2005

AbstractSeveral metabolic activities in dissociated cultures of newborn mouse brain were compared to the situation in vivo. The developmental activity pattern of cerebroside‐sulfotransferase, cyclic nucleotide phosphohydrolase, and β‐hydroxy‐β‐methyl glutaryl‐coenzyme A‐reductase and the synthesis and deposition of sulfatide and cholesterol in culture were estimated. The enzyme activity patterns in vivo and in culture are the same. Since the cultures show very little myelin formation, the parallel increase of enzyme activities necessary for myelination in vivo and in culture suggest the existence of intrinsic factors regulating the biochemical differentiation. In addition, the formation of the products, determined in culture, follows the patterns of the enzyme activities. Dissociated brain cell cultures are therefore a valid model for the study of biochemical parameters related to the synthesis of brain lipids during development.
Effect of denervation on cyclic nucleotide metabolism in different types of skeletal muscle of the rat
Authors: McLane Jerry A. , Held Irene R. 
Published: January 2005

AbstractSlow‐twitch soleus and fast‐twitch extensor digitorum longus muscles of the rat were denervated unilaterally by sciatic nerve section at mid‐thigh level. Activities of adenylate cyclase, guanylate cyclase, low Km and high Km cyclic AMP phosphodiesterase, and cyclic GMP phosphodiesterase were compared on the same, freshly prepared homogenates of denervated and shamoperated contralateral muscles one, two, three, or five days after surgery. As an early consequence of denervation, cyclic AMP metabolism was differentially affected in these different types of skeletal muscle. The adenylate cyclase activity of soleus muscle increased significantly by the second day following denervation and continued to rise through the fifth day, while this enzyme did not increase in denervated extensor digitorum longus even by the fifth day. The high Km cyclic AMP phosphodiesterase was already increased by day one in the denervated soleus, but not until the fifth day in the denervated extensor digitorum longus. Parallel increases beginning the first day were observed for the low Km cyclic AMP phosphodiesterase in both muscles. Since the activity of cytosolic cyclic AMP‐dependent protein kinase of soleus muscle was also increased two days following denervation, the changes in cyclic AMP synthetic and degradative enzymes apparently result in a rise in intracellular cyclic AMP concentration. Alterations of the cyclic GMP enzymes following denervation were similar in the soleus and extensor digitorum longus, but were delayed relative to the increases in activity in the cyclic AMP enzymes.
Cathechol‐O‐methyltransferase activity in cultured human skin fibroblasts from controls and patients with dystonia musculorum deformans
Authors: Breakefield Xandra O. , Braverman Muriel , Riker Donald Kay , Giller Earl L. 
Published: January 2005

AbstractFibroblasts provide a source of living cells that can be obtained easily from humans and used to evaluate inherited differences in the activities of enzymes important in neurotransmitter and drug metabolism. Here, we describe biochemical characteristics of catechol‐O‐methyltransferase (COMT, EC 2.1.1.6) activity in homogenates of cultured human skin fibroblasts. Many properties of the enzyme, including apparent affinity for dihydroxybenzoic acid and Sadenosyl methionine, optimal pH and (Mg++), and inhibition by Ca++, are similar to those reported in lysates of human erythrocytes. Culture and assay conditions have been established for optimal and reproducible measurement of COMT activity in individual fibroblast lines. In 16 control lines, COMT activity ranged from 115 to 263 pmol/min/mg protein with a mean of 181 pmol/min/mg protein. Enzyme activity did not vary with the age or sex of the donor. The COMT activities in fibroblasts from eight patients with dystonia musculorum deformans, an inherited movement disorder of unknown etiology, were not significantly different from controls. Monoamine oxidase (MAO, EC 1.4.3.4) type A activity was measured in 12 lines from patients with dystonia, and values did not differ significantly from age‐ and sex‐matched controls. We conclude that inherited variation in activity of these two catabolic enzymes is not sufficient to explain alterations in monoamine metabolism described in this disorder.
Membrane properties of a human neuroblastoma II: Effects of differentiation
Authors: Kuramoto T. , Werrbach‐Perez K. , Perez‐Polo J. R. , Haber B. 
Published: January 2005

AbstractThe SK‐N‐SH cell line is a human neuroblastoma which when grown under standard culture conditions remains relatively undifferentiated. The undifferentiated SK‐N‐SH cells are relatively inexcitable: they show only partial active responses to injections of current pulses and lack the depolarizing component of the action potential generating mechanism [Kuramoto et al, 1977]. In this study we report on the membrane properties of two subclones of the SK‐N‐SH, the SK‐N‐SH‐IN (referred to as IN) and the SK‐N‐SH‐Sy5Y (referred to as 5Y) which exhibit extensive morphological differentiation when grown with 1mM dibutyryl cAMP. Fully differentiated IN and 5Y cells have higher resting membrane potentials, in the range of −50 to −80 mV, and higher input resistance and time constants than do the undifferentiated SK‐N‐SH parental cell line. After 1 week in culture the differentiated IN and 5Y cells exhibit spike potentials in response to injection of current to the cell body. The presence of the Na+‐dependent depolarization was verified directly by the use of tetrodotoxin (TTX) and indirectly in experiments where veratridine (0.1 mM) markedly enhanced the influx of 22Na+. Taken together, the data indicate that generation of action potentials in these human neuroblastoma cells is to a large extent a function of morphological differentiation.
Covalent interaction of [3H]‐dopamine with rat brain proteins in vivo and with the dopamine‐reuptake site of nerve endings in vitro
Authors: Davies B. D. , Abood L. G. 
Published: January 2005

AbstractIsolated nerve endings have been demonstrated to undergo saturable, covalent interactions with [3H]‐dopamine under physiological conditions; and the reaction is greatly accelerated by flash photolysis with ultraviolet light. With intact nerve endings, under conditions where dopamine reuptake occurs, benztropine and cocaine (inhibitors of dopamine reuptake), but not atropine or haloperidol (a postsynaptic antagonist), prevent the reaction. The reaction also occurs in vivo following the intraventricular administration of [3H]‐dopamine, the reaction being greatest with mitochondria, followed by the nerve ending and myelin. With the use of sodium dodecylsulfate–gel electrophoresis, a number of proteins of varying molecular weight were labeled, and the pattern of labeling was similar in vitro and in vivo. One protein, with a MW of about 60,000 was labeled to an exceptionally high degree. A number of protein bands showed decreased radiolabeling in the presence of benztropine, a finding which suggests that they may be associated with the reuptake site. Both the addition of ascorbic acid and unlabeled dopamine inhibited the reactivity of [3H]‐dopamine, and the effects were concentration dependent. In the absence of photolysis, the reaction of [3H]‐dopamine to synaptic membranes attained saturation within 10 min, but with photolysis the reaction continued at a constant rate even after 20 min. The results are discussed in relation to the use of [3]‐dopamine as a photoaffinity label of the dopamine reuptake site and in relation to the nature of the reactions with and without photolysis.
Cerebral RNA synthesis in experimental hepatogenic encephalopathy
Authors: Albrecht Jan 
Published: January 2005

AbstractCerebral slices from rats subjected either to chronic (2‐ to 6‐month) administration of carbon tetrachloride or to prolonged (21‐day) portocaval shunting showed an increased above control ability to incorporate [3H]uridine in vitro into the RNA of the large cell nuclei, mostly derived from astrocytes but not the small oligodendroglial cell nuclei. This result is interpreted to indicate that brain reacts to extended periods of hepatogenic insult or chronic omission of hepatic circulation with a stimulation of RNA synthesis in the astrocytes. The possible relation of this phenomenon to the characteristic astrocytes response accompanying hepatogenic encephalopathy is discussed.
Physical properties of bovine white matter proteolipid apoprotein–sodium dodecyl sulfate complexes
Authors: Sakura J. David 
Published: January 2005

AbstractThe interaction of bovine white matter proteolipid apoproteins with sodium dodecyl sulfate (SDS) was studied. Equilibrium dialysis binding measurements show that the apoprotein binds approximately 1.5 gm SDS per gram protein at high ionic strength (T/2 =0.17). At low ionic strength (T/2 = 0.01) the protein binds only 0.90 gm per gram protein. The Stokes radius of the proteolipid protein is 40 Å. Based on the circular dichroism spectrum, the apoprotein contains less than 20% α‐helix structure in either aqueous or 0.1% sodium dodecyl sulfate solution. Analytical SDS‐PAGE (polyacrylamide gel electrophoresis) revealed two polypeptides. The major proteolipid protein migrated with an apparent molecular weight of 26,000 daltons. The minor proteolipid protein exhibited a molecular weight of 22,200 daltons. The apoprotein showed a marked tendency to aggregate on 8 M urea‐SDS‐polyacrylamide gels or when heated at 100° in excess detergent. These results suggest that the proteolipid proteins have hydrophobic regions that are not embedded within the detergent micelle but are exposed to the solvent. These regions may serve as sites for intermolecular aggregation.
Maturation of thalamic inputs into the associative cortical areas during postnatal ontogenesis in cats
Authors: Tolchenova G. A. , Shikhgasanova I. Sh. , Batuev A. S. 
Published: January 2005

AbstractThalamic afferents into the sensorimotor and parietal cortex (area 7) were studied using the method of retrograde axonal transport of horseradish peroxidase (HRP) in kittens of three age groups. Following HRP injection into the sensorimotor cortex of 1‐ to 3‐day‐old kittens, labeled cells were found in the following nuclei: ventral posterolateral (VPL), ventral posteromedial (VPM), medialis dorsalis (MD), centrum medianum (CM), ventral posteromedial (VPM), medialis dorsalis (MD), centrum medianum (CM), and centralis lateralis (CL). In 9‐ to 10‐day‐old kittens the number of labeled cells and density of reaction product within the cells was found to increse markedly. In 21‐ to 30‐day‐old kittens, besides the above‐mentioned nuclei, labeled cells were also revealed in n. ventralis lateralis (VL). A similar trend was seen following HRP injections into area 7. In 1‐ to 3‐day‐old kittens, labeled cells were found in n. lateralis posterior (LP), in n. ventralis anterior (VA), and in Pulvinar (Pulv). Both in the 9‐to 10‐day‐old and the 21‐ to 30‐day‐old kittens, labeled cells were also demonstrated in n. lateralis dorsalis (LD) and CL. For both of the cortical areas the number of labeled cells and the density of labeling within the cells increase during postnatal ontogenesis. This may be attributed to the growing number of axon terminals. In general, our results suggest that differences in the thalamic connections of single cortical areas can be distinguished during the postnatal ontogenesis of the brain.
Rapid axonal transport of phosphatidylinositol in the rabbit optic pathway
Authors: Alberghina M. , Viola M. , Giuffrida A. M. 
Published: January 2005

AbstractAt different time intervals (4 hr up to 24 days) after intravitreal injection of myo‐(2‐3H)‐inositol, the specific activity (sp act) of phosphatidylinositol (PtdIns) and water‐soluble compounds extracted from the retina, optic nerve (ON), optic tract (OT), lateral geniculate body (LGB), and superior colliculus (SC) was measured. Furthermore, 2 days after biocular injection of the labeled precursor, the specific activity of PtdIns and other major phospholipids in the various subcellular fractions (myelin, axolemma, synaptosomes, mitochondria, and microsomes) purified from ON + OT, from LGB, and from SC was evaluated. In the ON and OT, the phospholipids were labeled 8 hr after the precursor injection; in the LGB and SC after 8–12 hr. In all the optic components examined, the lipid specific activity reached a maximum at day 6 and decreased slowly until day 24 after injection. In the ON + OT, the specific activity of PtdIns, isolated from various subcellular fractions, decreased as follows: myelin > axolemma; in the LGB and SC as follows: microsomes > synaptosomes > myelin > mitochondria. The radioactivity present in the retina and in the optic pathway was exclusively localized in the PtdIns during the whole time interval studied. Ten days after the precursor injection, a high portion of the radioactivity transported was detected in the water‐soluble pool, separated from the ON and OT, whereas no significant counts in the corresponding LGB and SC pool were found. The kinetics of PtdIns labeling, observed in the different optic components, indicated a rapid axonal transport of the phospholipid; besides, the presence of labeled PtdIns in the purified myelin suggested a transaxonal migration of the phospholipid and its free precursor.
Differential effects of morphine withdrawal on cerebral β1‐ and β2‐adrenergic receptors
Authors: Kuriyama Kinya , Muramatsu Makoto , Ohkuma Seitaro , Tamura Jun‐Ichi , Ping Zuo Ping 
Published: January 2005

AbstractEffect of morphine dependence and its withdrawal on the 3H‐dihydroalprenolol (3H‐DHA) binding for βadrenergic receptors,β1 andβ2, was examined by a computerized analysis of biphasic Hofstee plots. The relative density ofβ1 andβ2 receptors in the rat cerebral cortex was found to be approximately 70% and 30%, respectively. In rats rendered dependent on morphine by a subcutaneous implantation of a morphine pellet, the 3H‐DHA binding toβ1 andβ2 receptors was not altered. During the stage of withdrawal induced by administration of naloxone, however, the 3H‐DHA binding to the cerebral particulate fractions was increased, and this increase was due to the increased binding sites inβ1 but not inβ2 receptor. On the other hand, the apparent affinities ofβ1 andβ2 receptors for atenolol and salbutamol, selective antagonists forβ1‐ andβ2‐adrenergic receptors, respectively, were not altered under these experimental conditions. These results suggest that an abrupt increase in cerebralβ1‐receptor binding sites occurs at morphine withdrawal, and the occurrence of such a supersensitivity in cerebralβ1 receptor may be involved in the exhibition and/or maintenance of the abstinence syndrome in morphine‐dependent subjects.
Do neuronal signals regulate potassium flow in glial cells? Evidence from an invertebrate central nervous system
Authors: Walz Wolfgang 
Published: January 2005

AbstractExperiments were conducted with the aid of intracellular microelectrodes to study physiological properties of neuropile glial cells in the central nervous system of the medicinal leech. The results showed significant contributions of both K+ and Cl− ions to the membrane potential. The transmitter substance 5‐hydroxytryptamine increased the K+ conductance of the cell membrane. On the basis of these experiments, a model for potassium homeostasis in leech neuropile is suggested, according to which excess K+ ions in the extracellular space lead to passive KCl fluxes across the glial cell membrane and the transmitter 5‐hydroxytryptamine induces a K+ release from glial cells into the extracellular space. Since 5‐hydroxytryptamine is known to be an inhibitory transmitter in the leech central nervous system, this release will occur in regions with inactive neurons, which may be specially well suited for neuronal reaccumulation of K+ ions.
Effect of hypoxia on the superficially exposed carbohydrates of subcellular fractions of guinea pig cerebral cortex
Authors: Rossowska Magdalena 
Published: January 2005

AbstractExperimental hypoxia led to changes in carbohydrate‐containing macromolecules located on the microsomal and synaptosomal membrane surface. It was found that hypoxia reduced the external membrane‐bound sialic acid content in microsomal and synaptosomal fractions.On the other hand, a decrease in fucose content of proteins in hypoxic synaptosomal fraction was found. Similarly, a decrease was observed in the amount of 3H‐labeled concanavalin A bound to the microsomal and synaptosomal glycoprotein fractions. Treatment of microsomal and synaptosomal fractions with galactose oxidase followed by reduction with tritiated potassium borohydride resulted in a significantly higher incorporation rate of tritium into the hypoxic membranes. This was accompanied by an increase in the endogenous glycoprotein galactose transferase activity both in microsomal and synaptosomal fractions.
Relationships between γ‐aminobutyrate and succinate cycles during and after cerebral ischemia
Authors: Benzi Gianni , Pastoris O. , Dossena M. 
Published: January 2005

AbstractSome metabolites (glycogen, glucose, glucose‐6‐phosphate, pyruvate, lactate, citrate, α‐ketoglutarate, succinate, fumarate, malate, glutamate, aspartate, γ‐aminobutyrate, glutamine, alanine, NH+4) were measured in rat cerebral cortex after 5 minutes of complete compression ischemia, as well as after 5, 15, or 30 minutes of recirculation following 5 minutes of ischemia.Complete ischemia induced a drop of glycolytic substrates and intermediates, consistent with the increase of lactate, succinate, alanine, and γ‐aminobutyrate, and with the decrease of malate, fumarate, and α‐ketoglutarate. These events may be regarded as an expression of the activation of the γ‐aminobutyrate cycle and of the succinate cycle, where succinate itself, in the absence of O2, acts as a terminal electron acceptor.During post‐ischemic recovery, cerebral parameters tended to normalize, except for the further increase of alanine and the still higher than normal content of both succinate and γ‐aminobutyrate, as an expression of the possible activation of the γ‐glutamyl and γ‐aminobutyrate cycles during recovery.
Effect of ischemia and hypoxia on rat brain glycolipids
Authors: Domańska‐Janik K. , Strosznajder J. , Zalewska T. 
Published: January 2005

AbstractHypoxia and ischemia produced the changes in the rat brain lipid composition. Moderate decreases in the content of phospholipids, cerebrosides, and gangliosides were observed. Three different experimental models of oxygen deficiency varied as to the degree of energy disturbances were correlated with their effect on the particular lipid classes. The decrease of cerebrosides content, but not gangliosides and phospholipids, could be attributed directly to energy disturbances and concomitant restriction of glucose supply to the hypoxic‐ischemic brain.
A quantitative ultrastructural study of the pinealocyte of the chipmunk (Tamias striatus) during the daytime and at night
Authors: Karasek Michal , King Thomas S. , Hansen John T. , Reiter Russel J. 
Published: January 2005

AbstractDay‐night differences in the areas of granular endoplasmic reticulum, Golgi apparatus, dense‐core vesicles, and lysosomelike bodies were analyzed morphometrically in the pinealocytes of the chipmunk. The area of lysosomelike bodies was greater at night and lower during the daytime. In contrast, the areas of granular endoplasmic reticulum and dense‐core vesicles were greater during daytime and lower at night. Our observations suggest the existence of 24‐hour rhythms in the areas of these structures, perhaps indicative of a pineal rhythm in secretion, whether indolic or peptidergic.
Cerebral uptake of amino acids in human subjects and rhesus monkeys in vivo
Authors: Sacks William , Sacks Shirley , Brebbia D. Robert , Fleischer Arthur 
Published: January 2005

AbstractIn experiments with 11 human subjects and 12 rhesus monkeys given 14C‐labeled amino acids intravenously, blood samples were drawn simultaneously from the femoral artery (A) and the superior bulb of the internal jugular vein (V). Analyses of labeled and unlabeled free amino acids indicated that both A‐V and V‐A differences resulted with each amino acid. In no case were there consistent A‐V or V‐A differences (excepting with L‐[methyl‐14C] methionine where consistent A‐V differences resulted). However, in experiments with rhesus monkeys, from 0.2% to 2.3% of the injected 14C‐labeled amino acids was taken up by brains 90–120 minutes after injection. Therefor, it was suggested that, in humans and monkeys in vivo, small but significant amounts of amino acids enter the brain from blood over a period of time by a bidirectional exchange mechanism.
Acceleration of the biosynthesis of rat striatal dopamine by incubation and by administration of γ‐butyrolactone
Authors: Dyck Lillian E. , Kazakoff Clement W. 
Published: January 2005

AbstractThe concentration of dopamine in striatal slices obtained from rats treated with an MAO inhibitor was increasd significantly by a 50‐minute incubatio in oxygenated Krebs buffer at 37°C. Administration of α‐methyl‐p‐tyrosine did not antagonize this small increase in dopamine. The extent of the incubatio‐induced increase was much greater in tissue obtained from control rats and was also greater than that resulting from the intraperitoneal administration of γ‐butyrolactone (GBL). Prior administration of α‐methyl‐p‐tyrosine, d‐amphetamine, apomorphine, or lergotrile significantly antagonized the increases in striatal dopamine levels induced by GBL administration or by incubation of striatal slices obtained from control rats. The prior administration of phenylethylamine, however, antagonized the incubation‐induced, but not the GBL‐induced, increase in striatal dopamine. In conclusion, the effect of incubating striatal slices on their dopamine levels was similar to that of administering GBL in that the incubation enhanced the activity of tyrosine hydroxylase that in turn produced an accelerated synthesis of dopamine.
De novo biosynthesis of nucleotides and of nucleic acids in different regions of developing rat brain: Effect of undernutrition
Authors: Serra I. , Vanella A. , Avitabile M. , Barcellona M. L. , Avola R. , Giuffrida A. M. 
Published: January 2005

AbstractThe effect of undernutrition on the de novo biosynthesis of nucleic acids in cerebral hemispheres, cerebellum, and brain stem of rats at different days of postnatal development was studied. The experiments were carried out in vitro by measuring the incorporation of [14C]‐formate into the adenine nucleotide of the acid‐soluble fraction of RNA and DNA, as well as into the thymine of DNA.The results obtained indicate that undernutrition during fetal and postnatal development impairs the de novo synthesis of the purine nucleotides of RNA and DNA at 5 days of age and delays it thereafter in the various brain regions examined, particularly in the cerebellum.