bluuebunny/crossref_metadata_2025_split huggingface dataset:
MYELIN SUBFRACTIONS IN DEVELOPING RAT BRAIN: CHARACTERIZATION AND SULPHATIDE METABOLISM
Authors: Benjamins Joyce A. , Miller Karen , McKhann G. M. 
Published: October 2006

AbstractCentrifugation of isolated myelin on discontinuous sucrose gradients resulted in a separation into three bands and a pellet. The three bands were morphologically identical to myelin, whereas the pellet consisted primarily of vesicular membranes. These four fractions differed from one another in their lipid‐to‐protein ratios and in molar ratios of cholesterol:phospholipid:galactolipid. All of the fractions contained proteins typical of myelin, although the proportions of the proteins varied, with the pellet being the lowest in basic protein and proteolipid protein. High activity of 2′,3′‐cyclic nucleotidase and low activity of cerebroside sulphotransferase further distinguished these fractions from the microsomal fraction. Distribution of radioactive sulphatide in the subfractions at 15 min after intracranial injection of radioactive sulphate indicated that newly‐labelled sulphatide first appeared in the lipid‐poor fractions, followed by the lipid‐rich fractions; results of pulse‐chase experiments also suggested this relationship. Several days or weeks after the injection of radioactive sulphate, most of the radioactive sulphatide was in the lipid‐rich fractions.
AXONAL TRANSPORT OF RADIOACTIVITY IN THE GOLDFISH OPTIC SYSTEM FOLLOWING INTRAOCULAR INJECTION OF LABELLED RNA PRECURSORS
Authors: Ingoglia N. A. , Grafstein B. , McEwen B. S. , McQuarrie I. G. 
Published: October 2006

AbstractAfter injection of the tritiated RNA precursors [3H]guanosine, [3H]uridine or [3H]orotic acid into the eye of goldfish, labelled TCA‐soluble material and RNA appeared to be axonally transported to the contralateral optic tectum. From the time courses of arrival in the tectum,‘average’rates of transport of 6 mm/day for the soluble material and 1·7 mm/day for the RNA were calculated. If the optic nerve was cut after the transported material had arrived in the tectum, about 60 per cent of the TCA‐soluble material disappeared by 7 days after the cut, but almost none of the RNA. After a further 8‐ to 13‐day period, the TCA‐soluble material had declined by a further 50 per cent from the 7‐day value, but the RNA by only 20 per cent. Thus, relatively little RNA was lost when the optic axons degenerated, an observation which suggested that the RNA might be extra‐axonal. However, if the optic nerve was crushed before the arrival of the transported material, RNA did not appear in the tectum until the regenerating optic nerve fibres arrived. Therefore, the presence of RNA must be dependent on intact nerve fibres. Moreover, in the earliest stages of regeneration the proportion of transported RNA to TCA‐soluble material was considerably higher than normal, suggesting that the regenerating fibres arrived in the tectum already carrying RNA. This implies that the RNA itself was transported in the optic fibres.
RELATIONSHIP BETWEEN THE RATE OF AXOPLASMIC TRANSPORT AND SUBCELLULAR DISTRIBUTION OF ENZYMES INVOLVED IN THE SYNTHESIS OF NOREPINEPHRINE
Authors: Oesch F. , Otten U. , Thoenen H. 
Published: October 2006

AbstractThe net rate of proximo‐distal transport of tyrosine hydroxylase, dopamine β‐hydroxylase, DOPA decarboxylase and choline acetyltransferase was determined by measuring the accumulation of these enzymes proximal to a ligature of the rat sciatic nerve. The rate of accumulation was constant for at least 12 h. For the enzymes involved in the biosynthesis of norepinephrine the rate of transport was correlated to their subcellular distribution and a close correlation between these two parameters was found. Dopamine β‐hydroxylase, an enzyme mainly localized in the particulate fraction of the sciatic nerve, showed the fastest rate of transport (1·94 mm/h) whereas DOPA decarboxylase, exclusively located in the high‐speed supernatant fluid, gave the slowest (0·63 mm/h) rate of transport. Tyrosine hydroxylase, predominantly located in the non‐particulate fraction of the sciatic nerve was transported much slower (0·75 mm/h) than dopamine β‐hydroxylase but still significantly (P < 0.005) faster than DOPA decarboxylase. The subcellular distribution of dopamine β‐hydroxylase in ganglia did not differ significantly (0·45 > P > 0·40) from that in the sciatic nerve, but in nerve endings a greater proportion of dopamine β‐hydroxylase was localized in particulate fractions. Tyrosine hydroxylase and DOPA decarboxylase were found exclusively in the non‐particulate fractions of ganglia. In the nerve endings of the effector organs a small but consistent portion of tyrosine hydroxylase was found in particulate fractions, whereas DOPA decarboxylase was exclusively localized in the high‐speed supernatant fluid.
EVIDENCE THAT THE MAJOR PROTEIN IN RAT SCIATIC NERVE MYELIN IS A GLYCOPROTEIN
Authors: Everly J. L. , Brady R. O. , Quarles R. H. 
Published: October 2006

AbstractEvidence is presented that the major protein of rat sciatic nerve myelin is a glycoprotein. When myelin proteins were separated by polyacrylamide gel electrophoresis, the major band which was stained with amido black–Coomassie blue was also stained with periodic acid‐Schiff reagents for carbohydrate. Radioactive labelling of myelin in vivo with [3H]leucine and [14C]fucose, followed by electrophoresis of the proteins, indicated that with both isotopes the major labelled peak corresponded to the major stained band. In addition, a second smaller peak of [14C]fucose migrated ahead of the major peak. Delipidated myelin contained galactose, mannose, fucose and sialic acid.
TURNOVER OF PHOSPHATIDYLCHOLINE IN CELL MEMBRANES OF ADULT RAT BRAIN1
Authors: Pasquini J. M. , Krawiec L. , Soto E. F. 
Published: October 2006

Abstract—Incorporation of radioactive choline into subcellular fractions of adult rat brains, after intracranial injection of the precursor, was studied at different times. Maximum labelling of phosphatidylcholine occurred at 5 h in all fractions, the highest specific radio‐activity being found in mitochondria. The specific radioactivity diminished rapidly for a few hours after the peak of maximum incorporation and continued to decrease thereafter at a much slower rate. The type of decay curve found in all fractions except myelin, indicated the possible presence of two populations of phosphatidylcholine with quite different turnover rates. The significance of these findings is discussed.
COMPARATIVE EFFECTS OF HYPOTHYROIDISM, HYPERTHYROIDISM AND UNDERNUTRITION ON THE PROTEIN AND NUCLEIC ACID CONTENTS OF THE CEREBELLUM IN THE YOUNG RAT
Authors: Gourdon J. , Clos J. , Coste C. , Dainat J. , Legrand J. 
Published: October 2006

Abstract— The effects of hypothyroidism, hyperthyroidism and undernutrition on the development of the protein and nucleic acid contents of the cerebellum were studied in young rats ranging in age from 6 to 35 days. Foetal and neonatal propylthiouracil treatment caused a delayed cell multiplication in the organ but this delay had disappeared at 35 days. As early as the age of 10 days, the total cerebellar RNA and protein contents in these hypothyroid animals were lower than in the normal animals but the mean cellular contents of RNA and protein were not lowered before the age of 21 days. Slight neonatal hyperthyroidism, induced by the daily injection of a relatively small dose of thyroxine, produced an accelerated cell multiplication during the first postnatal week and afterwards a delay in cell proliferation. In the hyperthyroid animals, the mean cellular protein content, initially higher than normal, tended to be lower at 35 days. At this age, the cell number had nearly returned to normal. Undernutrition directly led to a reduced cell proliferation and the reduced cell number still persisted at 35 days. At first, the cells were on the average larger than normal, but the effect on the mean RNA and protein contents per cell was not persistent in the underfed animals.This study correlates the degree of neonatal hyperthyroidism with the further development of the cell population of the cerebellum and emphasizes the importance of the events which take place just after birth in the cerebellum submitted to an excess or a deficiency of thyroid hormone. In addition, the results are discussed in relation to data concerning the morphogenetic action of thyroid and of underfeeding on the cerebellum.
ENZYMES OF THE γ‐GLUTAMYL CYCLE IN THE CHOROID PLEXUS AND BRAIN
Authors: Okonkwo P. Obiekwe , Orlowski Marian , Green J. P. 
Published: October 2006

Abstract—The presence of enzymes of the γ‐glutamyl cycle in the bovine and rabbit brain and choroid plexus is described. The activities of γ‐glutamyl transpeptidase, γ‐glutamyl cyclotransferase and γ‐glutamyl‐cysteine synthetase in the choroid plexus were found to be higher than in the brain. The activity of γ‐glutamyl transpeptidase in the choroid plexus was many times higher than the activity of the other enzymes. Brain and choroid plexus γ‐glutamyl transpeptidase were activated by Na+ and K+. Both brain and choroid plexus showed only a very limited capacity to metabolize [14C]5‐oxoproline to 14CO2.
RNA METABOLISM IN RABBIT BRAIN: STUDY WITH NEURON‐GLIA AND SUBCELLULAR FRACTIONS1
Authors: Yanagihara T. 
Published: October 2006

Abstract—Uridine incorporation into RNA of rabbit brain was studied by using an in vitro system for incubation of brain slices for up to 180 min. Neuron‐enriched and glia‐enriched fractions were prepared by ficoll density gradient centrifugation, and various subcellular fractions were prepared by sucrose density gradient centrifugation. Although the difference was not as great as in the case of l‐leucine incorporation into protein, the neuron‐enriched fraction consistently showed a higher specific radioactivity than the glia‐enriched fraction. The specific radioactivity of the nuclei increased promptly and remained high at 180 min; the increase in the microsomes was gradual. Comparison of these data suggests that both neuron‐enriched and glia‐enriched fractions retain high radioactivities in their nuclei at 180 min when a considerable portion of the ribosomal RNA in these fractions is not labeled. The sharp diffusion gradient of nucleotides is discussed in relation to the acid‐soluble radioactivity.
THE EFFECT OF PHOSPHOLIPASES ON THE ACTIVE UPTAKE OF NOREPINEPHRINE BY SYNAPTOSOMES ISOLATED FROM THE CEREBRAL CORTEX OF GUINEA PIG1
Authors: Sun A. Y. 
Published: October 2006

Abstract—Phospholipase A (EC 3.1.1.4) and phospholipase C (EC 3.1.4.3) were used for studying the role of phospholipid of synaptosomal membrane on norepinephrine uptake activity. Synaptosomes were isolated from cerebral cortex of guinea pigs and treated with phospholipase A or phospholipase C before the uptake experiments. Treatment of synaptosomes with phospholipase A has resulted in severe inhibition of norepinephrine‐uptake. Under similar conditions, the activity of synaptosomal (Na + K)‐ATPase (EC 3.6.1.4) was also inhibited by phospholipase A treatment whereas the activity of synaptosomal acetylcholinesterase (EC 3.1.1.8) was not affected. On the other hand, the norepinephrine‐uptake was not influenced by phospholipase C treatment. The inhibition of norepinephrine‐uptake after phospholipase A treatment may be due to the liberation of lyso‐components of phospholipids since a low concentration of lysolecithin as well as other detergents (deoxycholate and sodium dodecyl sulphate) also inhibit the uptake activity. However, electron microscopic examination indicated that the synaptosomal particles still maintain their morphological features after phospholipase A treatment. It is possible that the active uptake of norepinephrine depends upon the fine arrangement of phospholipids present at the active sites of the synaptosomal membrane.
PURIFICATION OF SOLUBLE GLYCOPROTEINS FROM HUMAN NERVOUS TISSUE AND LIVER
Authors: Haglid K. G. , Rounnbauck L. , Stavrou D. 
Published: October 2006

Abstract—The isolation of some water‐soluble, 50% methanol‐soluble glycoproteins from human normal brain, human ependymoma and human liver is reported. One of them (AM protein) has a similar, or even identical, electrophoretic mobility to brain‐specific protein S‐100 under certain electrophoretic conditions. Although bands of identical mobility are found in both brain and liver samples, we lack experimental evidence, at the present stage of this work, to draw conclusions on the identity (or relatedness) of such proteins. On the other hand, the brain‐soluble glycoproteins appear to be antigenically different from brain protein S‐100, from brain α2‐glycoprotein and from GP 350 glycoprotein.
PHOSPHOLIPID METABOLISM IN CULTURED NEUROBLASTOMA AND GLIOMA CELLS INCUBATED WITH CARBAMYLCHOLINE AND NOREPINEPHRINE
Authors: Eichberg J. , Shein H. M. , Hauser G. 
Published: October 2006

Abstract—Cultures of cloned neuroblastoma cells (N1E) in stationary phase and cloned glioma cells (C21) in confluency showed substantial differences in phospholipid composition. As a percentage of lipid P, N1E contained more phosphatidylcholine, less ethanolamine phosphoglycerides and much less sphingomyelin than C21. When incubated with 32Pi both cell lines incorporated comparable amounts of radioactivity into total phospholipids. In NIE, phosphatidylcholine contained much more and phosphatidylinositol and phosphatidic acid somewhat less label as compared to C21. The presence in the incubation medium of either norepinephrine or carbamylcholine failed to elicit stimulation of 32P incorporation into any phospholipid class.
EFFECT OF COLCHICINE ON THE DELAYED APPEARANCE OF LABELLED PROTEIN INTO SYNAPTOSOMAL SOLUBLE PROTEINS1
Authors: Crothers S. D. , McCluer R. H. 
Published: October 2006

Abstract—The effect of colchicine administration on the accumulation of radiolabelled soluble protein of brain synaptosomes was studied. Following injection of radiolabelled leucine, colchicine (injected bitemporally) was shown to block this delayed accumulation in limited brain areas. This effect supports the conclusion that the delayed appearance of label is a reflection of axoplasmic transport and demonstrates that colchicine can be utilized to block such transport in limited brain areas.
UPTAKE OF 3‐O‐METHYL‐d‐GLUCOSE INTO CULTURED HUMAN GLIOMA CELLS
Authors: Edström A. , Kanje M. , Walum E. 
Published: October 2006

Abstract—Human glioma cells (138 MG) were found to take up 3‐O‐methyl‐d‐glucose (3‐OMG) by a saturable low affinity transport system with a Km of 20 mm and a Vmax of 500 nmol/mg protein/min. About 20 per cent of the total uptake was due to passive diffusion. d‐Glucose was a competitive inhibitor with a Ki of 10 mm. Follow‐up experiments indicated that the same transport mechanism is involved in the uptake of n‐glucose and 3‐OMG. Phloretin (0·02 mm) and cytochalasin B (0·002 mm) strongly inhibited the uptake of 3‐OMG, whereas phlorizin (0·02 mm), ouabain (0·1 mm), NaCN (0·5 mm) and iodoacetic acid (1·0 mm) had no effect. The data suggest that 3‐OMG and d‐glucose enter 138 MG cells mainly by a Na+‐independent passive carrier‐mediated transport system. Serum‐deprivation doubled the population doubling time (Td) without affecting the total uptake of 3‐OMG. An increase in the non‐specific (diffusional) uptake was balanced by a decrease in the specific (carrier‐medíated) uptake. After addition of dibutyryl cyclic AMP (dbcAMP, 0·25 mm) the cells attained a morphology characteristic of differentiated glia cells. Td was maintained unchanged. The non‐specific uptake of 3‐OMG was not affected in cells grown in serum‐containing medium plus dbcAMP, whereas the specific uptake increased by 40 per cent and there‐fore also the total uptake. Similar, but more pronounced, changes were observed if serum‐deprived cells were treated with dbcAMP.
ALTERATIONS IN ACETYLCHOLINESTERASE ISOENZYME PATTERN OF HIPPOCAMPUS AFTER SEPTAL LESIONS IN RAT BRAIN
Authors: Oderfeld‐Nowak Barbara , Skangiel‐Kramska Jolanta 
Published: October 2006

Abstract—The effect of septal lesions upon the AChE (EC 3.1.1.7) isoenzymic pattern in the hippocampus of the rat brain was studied 1–3 months after surgery by means of polyacrylamide disc electrophoresis.Alterations in the isoenzymic pattern were found in the membrane‐bound but not in the soluble fraction of the enzyme. In addition to the two slowly migrating bands seen in the membrane‐bound AChE fraction of the normal hippocampus, the fast‐migrating isoenzyme becomes visible.
CALCIUM‐DEPENDENT RELEASE OF EXOGENOUSLY LOADED γ‐AMINO‐[U‐14C]BUTYRATE FROM SYNAPTOSOMES: TIME COURSE OF STIMULATION BY POTASSIUM, VERATRIDINE, AND THE CALCIUM IONOPHORE, A23187
Authors: Redburn Dianna A. , Shelton D. , Cotman C. W. 
Published: October 2006

Abstract—Synaptosomes which had taken up [14C]GABA were applied to a filter and rapidly perfused with various solutions in order to study the time course of release of this putative transmitter and the characteristics of its release. Depolarization of the synaptosomes with veratridine or 56mM‐K+ or pretreatment with the Ca2+ ionophore, A23187, increased the calcium‐dependent efflux of [14C]GABA. Release of [14C]GABA was increased by Ca2+ within 0.3 s of exposure, and the maximal release rate was not maintained for longer than 0.6 s. The reduction in the rate of release was not attributable to a decrease in calcium influx, but rather appeared to reflect fatigue at some subsequent stage in release. Stimulation by 56mM‐K+ also elicited a calcium‐independent increase in the efflux of radioactive GABA, which appeared to arise in part from subcellular particles other than synaptosomes.
ISOLATION OF HYDROPHOBIC PROTEINS BINDING AMINO ACIDS. STEREOSELECTIVITY OF THE BINDING OF L‐[14C]GLUTAMIC ACID IN CEREBRAL CORTEX
Authors: Robertis E. De , DE Plazas Sara Fiszer 
Published: October 2006

AbstractFrom the total lipid extract of ncrve‐ending membranes or the homogenate of cerebral cortex a hydrophobic protein fraction binding L‐[14C]glutamic acid was separated by chromatography on Sephadex LH20. This protein could only be partially separated from the [14C]GABA‐binding protein and from the lipids that are present in the fraction; however, it was demonstrated that both amino acids bind to different sites. The saturation of the binding showed a high (Kd1= 0.3μM), a medium (Kd, = 5 μM) and a low (Kd, = 55 μM) affinity binding site. The high affinity binding site had a binding capacity of 0.53 nmol/mg of protein and was highly stereoselective for the L‐enantiomer. The binding of L‐[14C]glutamic acid was not inhibited by GABA, was slightly inhibited by glycine and glutamine and was strongly inhibited in a progressive order by DL‐a‐methylglutamic acid, L‐nuciferine, L‐aspartic acid and L‐glutamic acid diethyl ester. These results are compared with those previously obtained with the L‐glutamic acid‐binding protein isolated from crustacean muscle. The stereoselectivity of the binding and the possible role of this protein in synaptic transmission are discussed.
IDENTIFICATION OF D‐ASPARTIC ACID IN THE BRAIN OF OCTOPUS VULGARIS LAM
Authors: D'Aniello A. , Giuditta A. 
Published: October 2006

Abstract— An assay method based on the use of specific oxidases has been used to search for D‐amino acids in the organs of Octopus vulgaris. A high concentration of D‐aspartate has been detected in the central brain and in the optic lobes but not in non‐nervous organs.Other D‐amino acids appear to be absent from brain and from other tissues.
PHOSPHOINOSITIDE KINASES IN CHICK BRAIN AND SCIATIC NERVE, A DEVELOPMENTAL STUDY
Authors: SHAIKH NISAR A. , PALMER F. B. ST. C. 
Published: October 2006

Abstract—Phosphatidylinositol kinase and diphosphoinositide kinase activities were measured in homogenates of brain and sciatic nerve of developing chick embryos and chicks. Characteristics of the chick nervous system enzymes were similar to those reported for rat brain. Diphosphoinositide kinase was inhibited by high concentrations of ATP and by low concentrations of triphosphoinositide. Both activities were greatly enhanced by the non‐ionic detergent, Cutscum, and the ratio of detergent to protein in the reaction mixture was important. Optimum phosphatidylinositol kinase activity required a ratio of 7 : 1 for both tissues. The optimum ratio for diphosphoinositide kinase was 3:1 for nerve homogenates and 0.6:1 for brain. Cutscum increased the concentration of diphosphoinositide that is required for maximum diphosphoinositide kinase activity.Developmental changes were the same for both kinase activities, which were low in unmyelinated brain and sciatic nerve. The activities correlated with the concentration of polyphosphoinositides in chick brain where they increased 4‐5 fold during the period of active myelination and remained high in the mature brain. The kinase activities correlated with the rate of triphosphoinositide deposition in sciatic nerve. Following a 2‐3 fold increase during the initial phase of myelination the activities declined to values as low as those of embryonic nerve.
THE EFFECTS OF PENTOBARBITONE‐SODIUM ANAESTHESIA, SHOCK AVOIDANCE CONDITIONING AND ELECTRICAL SHOCK ON ACETYLCHOLINESTERASE ACTIVITY AND PROTEIN CONTENT IN REGIONS OF THE RAT BRAIN
Authors: Evans Christine A. , Kerkut G. A. 
Published: October 2006

Abstract— Pentobarbitone sodium anaesthesia was found to produce an increase in protein content in some regions of the rat brain, i.e. posterior cortex, caudate nucleus, and a decrease in protein content in the ventral cortex.Acetylcholinesterase expressed in terms of wet weight was found to increase in the cerebellum, medulla, and to decrease in the medial cortex, hippocampus, thalamus and caudate nucleus. The changes in activity were not explicable in terms of a direct effect of the anaesthetic on the enzyme. A decrease in protein content of rat brain was observed in the frontal cortex, ventral cortex, hippocampus and caudate nucleus after electrical shocks. Following shock avoidance conditioning procedure (shuttle‐box), decreases in protein content were observed in the medial cortex, posterior cortex, cerebellum and ventral cortex; in the thalamus an increase in protein content was observed.Changes in AChE activity were observed following footshock in the frontal cortex and medulla where there was an increase in activity and in the caudate nucleus, hypothalamus, thalamus, and olfactory tubercle where there was a decrease in activity.Following shock avoidance conditioning the activity of the AChE increased in posterior cortex, hippocampus, thalamus and hypothalamus and the activity of the enzyme decreased in the ventral cortex.