bluuebunny/crossref_metadata_2025_split huggingface dataset:
IMMUNOCHEMICAL PROPERTIES OF S‐100 PROTEINS AND THEIR SUBUNITS
Authors: Mahadik S. P. , Graf L. , Korenovsky A. , Rapport M. M. 
Published: October 2006

Abstract— The immunological activities of two populations of bovine S‐100 proteins with anti‐S‐100 serum were studied by complement fixation and rocket immunoelectrophoresis. The reactivities of subunits of these two populations were studied by crossed immunoelectrophoresis and rocket immunoelectrophoresis. Although the two populations conformed in all respects to the properties of S‐100 protein, the immunological reactivity of one, III‐IVa‐1, was significantly lower than that of the other, III‐IVb‐1. The difference was much larger when the S‐100 protein fractions were isolated in the absence of aids (mercaptoethanol, EDTA, EGTA, protease inhibitors). With bovine S‐100 fractions, the three subunits separated by differences in charge as well as the four subunits separated by differences in molecular weight all reacted with the same antibody molecules in the antiserum. The reactivities of the subunits showed large quantitative differences.Two populations of S‐100 proteins from rat brain also showed differences in reactivity with anti‐S‐100 serum. The two subunits in each of these fractions reacted with anti‐S‐100 serum but with quantitative differences, the larger having almost double the activity of the smaller. These results provide firm evidence for the heterogeneity of S‐100 proteins based on immunological activity of their subunit components. Different molecular species of S‐100 proteins probably differ considerably in their reactivity with antibodies to S‐100 protein. Some of the more reactive molecular species also appear to be much more labile, since the reactivity of some S‐100 protein fractions was considerably reduced when they were isolated in the absence of aids.
EFFECTS OF SULFHYDRYL REAGENTS ON BRAIN MICROTUBULE‐ASSOCIATED ATPase ACTIVITY IN VITRO
Authors: Wallin Margareta , Larsson H. , Edström A. 
Published: October 2006

Abstract— The effects of two sulfhydryl reagents, PCMBS (p‐chloromercuribenzene sulfonic acid) and NEM (N‐ethylmaleimide) on microtubule‐associated Mg2+ ‐and Ca2+ ‐ATPase activity were studied in a MTP (microtubule proteins) preparation and in a MAP (microtubule‐associated proteins) fraction. In the MTP preparation at pH 6.8, PCMBS stimulated the Mg2+ ‐ATPase activity at low concentrations and inhibited at higher, whereas the Ca2+ ‐ATPdse activity was only inhibited. NEM affected the activity in a similar way. At pH 8.0 PCMBS was only inhibitory. NEM showed stimulatory effects over a broader concentration range.Preincubation in the presence of ATP counteracted the stimulatory effects of both PCMBS and NEM on Mg2+ ‐ATPase at pH 6.8.In the MAP fraction at pH 6.8 PCMBS and NEM caused similar but less pronounced effects on the Mg2+ ‐and Ca2+ ‐ATPase.The results show that brain microtubule‐associated ATPase activity is similar to dynein and myosin ATPases with respect to biphasic alteration by sulfhydryl reagents.
THE INCORPORATION OF GLUCOSE INTO α‐1, 4‐GLUCAN PROTEINS OF BOVINE RETINA MEMBRANES 1
Authors: Curtino Juan A. , Maccioni Hugo J. , Caputto Ranwel 
Published: October 2006

Abstract—Incubation of bovine retina membranes with UDP‐[14C]glucose resulted in the incorporation of [14C]glucose into endogenous α‐1, 4‐glucan proteins. The transferring system was concentrated in membranes that floated at 0.94 and 1.10m‐sucrose when centrifuged in a discontinuous sucrose density gradient and was almost absent in the rod outer segment (ROS) and the 100, 000 g supernatant fractions. The glucan proteins labelled by incubation with the radioactive sugar nucleotide at micromolar concentrations were distinguished in two fractions by their solubilities in trichloroacetic acid (TCA): glucan protein‐I (GP‐I), insoluble in TCA, and glucan protein‐II (GP‐II), soluble in TCA and precipitable by ethanol from the TCA soluble fraction. GP‐I and GP‐II were precipitated by trichloroacetic acid‐phosphotungstic acid (TCA‐PTA). A third fraction, glucan protein‐III (GP‐III) was found when incubations were carried out with UDP‐[14C]glucose at millimolar instead of micromolar concentrations. GP‐III was soluble in TCA and in TCA‐PTA and precipitable by ethanol from the TCA soluble fraction. GP‐II was excluded from a Sephadex G‐200 column and showed a greater size than GP‐I in a Sepharose 2B column. The radioactive residues obtained from the glucan proteins after digestion with pronase were totally included in a Sephadex G‐25 column and were of a greater size than the labelled residues released with salivary α‐amylase. Only radioactive maltose was found after a‐amylase treatment. When membranes containing labelled GP‐I and GP‐II were incubated with unlabelled UDP‐glucose at millimolar concentrations, GP‐I was converted into GP‐II and GP‐III was formed.
FRACTIONATION OF SOLUBLE BRAIN GLYCOPROTEINS BY AFFINITY AND HYDROXYLAPATITE CHROMATOGRAPHY
Authors: Langley O. K. 
Published: October 2006

Abstract—A separation of soluble brain proteins and Con A‐binding glycoproteins by chromatography on calcium hydroxylapatite in the presence of SDS is described. Seventeen Coomassie Blue‐stained bands were detected by polyacrylamide gel electrophoresis in SDS of Con A‐binding glycoproteins of the soluble fraction of rat brain: 16 of these were found by in vivo uptake of [3H]fucose to be fucosylglycoproteins. Hydroxylapatite chromatography yielded several glycoprotein pools, each of which was shown by gel electrophoresis to contain between 4 and 8 individual glycoproteins. Such pools were enriched in [36H]fucose relative to the brain soluble fraction by factors of between 6 and 21. Preliminary experiments demonstrate that this method is also applicable to the fractionation of membrane‐bound glycoproteins.
The Effects of Scorpion Venom Toxin on the Release of Amino Acid Neurotransmitters from Cerebral Cortex In Vivo and In Vitro
Authors: Coutinho‐Netto J. , Abdul‐Ghani A.‐S. , Norris P. J. , Thomas A. J. , Bradford H. F. 
Published: October 2006

Abstract: Tityustoxin, the active component of the venom of the Brazilian yellow scorpion Tityus serrulatus, caused specific release of the neurotransmitter amino acids glutamate, aspartate and GABA in vivo from the superfused sensori‐motor cortex of conscious unanesthetised rats and in vitro from rat cortical synaptosomes. The effects on synaptosomes appear to be due to a depolarising action. Synaptosomal potassium levels were depleted by the toxin. The action was also blocked both in vivo and in vitro by tetrodotoxin and was Ca2+ ‐dependent. The uptake of [U‐14C]GABA was inhibited by tityustoxin but this action was prevented by tetrodotoxin (1 μm). Since the release of [U‐14C]GABA from synaptosomes due to the tityustoxin was also prevented by ietrodotoxin under identical circumstances, it is concluded that the tityustoxin has a primary action on release of neurotransmitters rather than on uptake.
Accumulation of Cyclooxygenase Products of Arachidonic Acid Metabolism in Gerbil Brain During Reperfusion After Bilateral Common Carotid Artery Occlusion
Authors: Gaudet Robert J. , Alam Iftekhar , Levine Lawrence 
Published: October 2006

Abstract: Several of the cyclooxygenase products of arachidonic acid were measured in the cerebral hemispheres of gerbils subjected to transient interruption of the cerebral circulation. The levels of PGD2, PGF2α, PGE2, TXB2, 13,14‐H2‐15‐keto‐PGE2, and the stable nonenzymic product of prostacyclin, 6‐keto‐PGF1α, were not altered at the end of a 5‐min period of ischemia. However, the onset of reperfusion was accompanied by a rapid accumulation of these products. Levels were highest during the initial period of reperfusion, then decreased to approach control levels after 120 min. PGD2, PGF2α, and PGE2 were the predominant metabolites detected. This postischemic accumulation of arachidonic acid metabolites could be blocked by prior administration of inhibitors of cyclooxygenase activity.
Localization of Hexokinase in Neural Tissue: Electron Microscopic Studies of Rat Cerebellar Cortex
Authors: Kao‐Jen Judy , Wilson John E. 
Published: October 2006

Abstract: The distribution of hexokinase (ATP:d‐hexose 6‐phosphotransferase, EC 2.7.1.1) in the rat cerebellar cortex has been studied at the electron microscopic level using the peroxidase‐antiperoxidase procedure. Extensive staining of cytoplasmic regions, with some increased staining at mitochondrial profiles, was seen in the cell bodies of both neurons (basket, stellate, Lugaro, Golgi, and granule cells) and astrocytes. Oligodendrocytes showed little or no detectable staining. Purkinje cell perikarya were much less intensely stained than were the perikarya of other neurons. The initial portion of the Purkinje dendrite was, like the perikaryon from which it emerged, lightly stained. More intense staining was seen in the secondary and tertiary branches of the Purkinje dendrite, but the terminal branches were devoid of stain. Granule cell dendrites were well stained in their initial portions but devoid of stain in their terminal dendritic digits which form part of the cerebellar glomeruli. In contrast to the unstained granule cell dendritic digits, the central mossy fiber nerve terminal of the glomerulus exhibited intense staining of the mitochondrial profiles and of synaptic vesicles adjacent to the mitochondria. Axons of basket cells showed intense staining in the segments adjacent to the Purkinje cell soma, while terminal twigs of the basket axons in the pinceau surrounding the (unstained) initial segment of the Purkinje axon showed markedly decreased staining intensity. These results indicate that there may be substantial variation in hexokinase levels between the various regions of neuronal processes. Hexokinase was seen at both cytoplasmic and mitochondrial locations in a variety of cells. It does not appear likely that location of hexokinase can be directly correlated with cell type, i.e., with neurons versus glia.
Regional and Subcellular Distribution of S‐Adenosylhomocysteine Hydrolase in the Adult Rat Brain
Authors: Broch Ole Jacob , Ueland Per Magne 
Published: October 2006

AbstractThe regional distribution of S‐adenosylhomocysteine hydrolase was determined in the rat brain. Small variations in enzyme activity between different regions were observed. Highest activity was found in hypothalamus and bulbus olfactorius, the least in pons and medulla. About 70% of the enzyme activity was recovered in the soluble fraction of the tissue homogenate and 25% was localized to the crude mitochondrial fraction. The corresponding values for lactate dehydrogenase were 40% and 50%, respectively. The small amount of enzyme (5%) sedimenting with the nuclear fraction could be explained by contamination of this fraction with soluble proteins and synaptosomes. Further separation of the crude mitochondrial fraction by discontinuous sucrose gradient centrifugation showed that most of the enzyme activity was localized to the synaptosomes, but a substantial amount was found in the top layer of the gradient. The relative specific activity of lactate dehydrogenase in the top layer was less than that of S‐adenosylhomocysteine hydrolase. No time‐dependent leakage of S‐adenosylhomocysteine hydrolase from the synaptosomes could be demonstrated. After hypoosmotic treatment of the crude mitochondrial fraction and separation of this fraction on a discontinuous sucrose gradient, S‐adenosylhomocysteine hydrolase and DOPA decarboxylase showed the same distribution in the gradient and were recovered in the cytoplasmic fraction.
A Sensitive and Reliable Assay for Dopamine (β‐Hydroxylase in Tissue
Authors: Sperk Günther , Galhaup Ingrid , Schlögl Elisabeth , Hörtnagl Heide , Hornykiewicz Oleh 
Published: October 2006

Abstract:A new assay procedure for dopamine β‐hydroxylase (DBH) in tissue extracts is described. Solubilized DBH was adsorbed from crude extracts on Concanavalin A‐Sepharose (Con A‐Sepharose), resulting in enrichment of the enzyme as well as removal of endogenous catecholamines and inhibitory substances. The enzymatic assay was carried out with DBH still adsorbed to Con A‐Sepharose. The adsorption of the DBH to Con A‐Sepharose offers three advantages over previous assay procedures. (1) Because of removal of the endogenous inhibitory substances, a single Cu2+ concentration can be used for the determination of DBH activity, regardless of the tissue dilution or inhibitor content of the analysed sample. Using this procedure, the optimal Cu2+ concentration for DBH of bovine adrenal gland extracts was 3 μM and for rat brain 10 μM. (2) Because of removal of endogenous catecholamines, dopamine, the main physiological substrate of DBH in noradrenergic neurons, can be used for the assay. The enzymatic reaction product, noradrenaline, was determined by high performance liquid chromatography and electrochemical detection (hplc‐ec). This procedure resulted in an approx. 10‐fold increase in sensitivity of the assay compared with other procedures, e.g., the radioenzymatic assay. (3) Direct determination of the immediate product of the enzymatic reaction (noradrenaline) permits kinetic analysis. It was found that the Michaelis constants for the substrate (dopamine) and co‐factor (ascorbic acid) (2 mM and 0.65 mM, respectively) determined in bovine adrenal tissue extracts by the described procedure were identical with the values for the purified DBH preparation.
Accessibility of Galactosyl Ceramides to Probe Reagents in Central Nervous System Myelin
Authors: Linington C. , Rumsby M. G. 
Published: October 2006

Abstract:The suitability of isolated central nerve myelin preparations for probe labelling studies was assessed and the accessibility of galactosyl ceramides in myelin to galactose oxidase and sodium periodate was determined. Isolated myelin preparations present a uniform external membrane surface to added probes because lamellae in the myelin sheath separate at their external apposition surfaces exclusively during isolation. The cytoplasmic apposition remains intact in isolated myelin. Cationised ferritin can gain access along external apposition regions of inner lamellae in multilamellar fragments of isolated myelin, indicating that proteins and lipids on the external membrane surface will be accessible to probes. Over 50% of the total galactosyl ceramides of myelin are accessible to galactose oxidase attack; hydroxy fatty acid‐ and nonhydroxy fatty acid‐containing cerebrosides are equally attacked. Sodium periodate attacks over 90% of the galactosyl ceramides in isolated myelin at 20°C and electron micrographs of the periodate‐treated myelin reveal changes at the external apposition only. Galactosyl ceramides in vesicles of myelin lipid vesicles are not so readily attacked by periodate. The disposition of galactosyl ceramides in the myelin lamellae is discussed.
The Relationship Between the Stimulation of Dopamine Synthesis and Release Produced by Amphetamine and High Potassium in Striatal Slices
Authors: Schwarz Roy D. , Uretsky Norman J. , Bianchine Joseph R. 
Published: October 2006

Abstract:The effects of amphetamine (amph) and high K+ on the synthesis and release of dopamine (DA) were compared in striatal slices. Both agents stimulated DA synthesis as well as release. For both agents, Ca2+ was required for the initiation of synthesis stimulation as well as for the maintenance of this stimulation. The addition of EGTA to medium containing slices that were already stimulated by 1.0μm‐amph or 55 mm‐K+ markedly reduced the stimulation of DA synthesis. Although it has been reported that high K+ activates soluble tyrosine hydroxylase (TH), neither high K1 nor amph appeared to increase the affinity of the synthetic cofactor, 6‐MPH4, or decrease the affinity of the catechol, DA, for TH. This finding was supported by the observation that the inhibitory effect of L‐DOPA on DA synthesis in slices, in which synthesis was stimulated by either agent, was not decreased. Although both 1.0μM‐amph and 55 mm‐K® stimulated the release of [3H]DA from striatal slices, the release produced by K+ was Ca2+‐dependent, whereas release produced by amph did not occur at any concentration tested. Studies on pH requirements for both synthesis and release also confirmed a similarity between amph and K1 in stimulating synthesis but not in stimulating release. These results suggest that depolarizing agents, such as high K1, couple synthesis and release of DA by a Ca2+‐dependent mechanism. In contrast, the simultaneous stimulation of synthesis and release by amph is not regulated by Ca2+.
Chloroquine Intoxication Induces Ganglioside Storage in Nervous Tissue: A Chemical and Histopathological Study of Brain, Spinal Cord, Dorsal Root Ganglia, and Retina in the Miniature Pig
Authors: Klinghardt Georg W. , Fredman Pam , Svennerholm Lars 
Published: October 2006

Abstract :The effect of chronic chloroquine intoxication on lipid composition, particularly the gangliosides, was studied in the nervous system of miniature pigs, type Göttingen. The tissues examined were cerebrum, spinal cord, dorsal root ganglia and retina. Chloroquine was given in the diet in doses of 2.0‐3.5 g/kg food. The intoxication of the pigs was started at the age of 100–240 days and continued for 177‐219 days. The control pigs received the same diet without chloroquine. The ganglioside concentration was increased in all the tissues examined. Dorsal root ganglia and retina were the tissues affected most and showed a twofold increase. This corresponded to the light and electron microscopically demonstrated extensive storage process in the perikarya of dorsal root ganglion cells and inner ganglion cells of the retina. Under light microscopy the storage material was granular, intensely PAS‐positive and dissolved by paraffin embedding. The electron microscopical equivalent consisted of conglomerates of membranous lysosomal residual bodies. In cerebrum the ganglioside concentration was increased by 12%. Storage in the brain varied widely between different systems and types of cells. The allocortex was much more affected than the isocortex. Certain inhibitory ganglion cell types, such as the basket cells, exhibited the most massive storage of all. The spinal medulla was morphologically less involved but showed approximately the same ganglioside increase, though not statistically significant. With the exception of cerebrum the increase in the tissues examined involved all the individual gangliosides, most severely ganglioside GM2 and three fucogangliosides. In cerebrum only the ganglioside GM2 was increased more than the other gangliosides. Chloroquine intoxication did not affect the concentration of phospholipids or cholesterol in the cerebrum, spinal cord or dorsal root ganglia, but in retina the acidic phospholipids were significantly increased.
Specific Binding of a 125I‐Substance P Derivative to Rat Brain Synaptosomes
Authors: Viger A. , Beaujouan J. C. , Torrens Y. , Glowinski J. 
Published: October 2006

Abstract:Binding characteristics of 125I‐labeled Bolton‐Hunter substance P (125I‐BHSP), a radioactive analogue of substance P, were studied with a crude syn‐aptosomal fraction (P2) of the rat brain. A specific binding of 125I‐BHSP that was saturable, reversible, and temperature dependent was demonstrated. Under the conditions of the binding assay (20°C, 5 min), nonspecific binding represented no more than 25% of total binding, and in contrast to [3H]dopamine 125I‐BHSP was not taken up within synaptosomes by a ouabain‐sensitive process. Scatchard analysis indicated the existence of a single population of noninteracting sites with a high affinity (KD, 470 pM) and a low‐density (Bmax, 13 fmol/mg protein). Substance P and different substance P analogues were tested for their competitive potencies in inhibiting 125I‐BHSP binding to synaptosomes. (Tyr8) substance P, substance P, and BHSP strongly inhibited 125I‐BHSP specific binding. Among various tachykinins, physalaemin was the most potent (one fourth the potency of substance P). When substance P C‐terminal fragments were tested for their ability to compete with 125I‐BHSP binding, a good relationship was found between competitive activity and peptide length. N‐terminal fragments of substance P were ineffective. However, (nor‐Leu11)substance P and the methyl ester of substance P1‐11 slightly reduced 125I‐BHSP binding. (D‐Pro2, D‐Phe7, D‐Trp9) substance P and (D‐Pro2, D‐Trp7,9)substance P, two substance P antagonists, were also tested. (D‐Pro2, D‐Trp7,9) substance P was the only one to inhibit 125I‐BHSP binding even slightly. Results were compared with those previously obtained concerning 125I‐BHSP binding to mesencephalic embryonic cells in primary cultures using similar conditions for the binding assay.
Purification and Characterization of Myosin from Calf Brain
Authors: Malik Mazhar N. , Fenko Michael D. , Scotto Lois , Merz Pat , Rothman Jeffrey , Tuzio Helen , Wisniewski Henryk M. 
Published: October 2006

Abstract:Actomyosin complex was extracted from the brain cortex in a medium consisting of low salt, ATP, and EDTA, in the presence of protease inhibitors, followed by ammonium sulfate fractionation. Myosin was then purified from the actomyosin. Myosin obtained according to the procedure used was significantly contaminated with actin high (>200,000 dalton) and low molecular weight proteins. Therefore, an alternative method based on affinity chromatography (Blue Dextran/Sepharose) and gel filtration (Sepharose 4B) was developed to purify myosin. This procedure yielded myosin that was >95% pure as judged by electron microscopy and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. The subunit composition of purified brain myosin was monitored by sodium dodecyl sulfate‐polyacrylamide gel also containing a urea gradient. A closely migrating triplet in the heavy chain and three light chains, LC1, LC2, and LC3, of Mr 21,000, 19,000, and 17,000, respectively, were observed. These findings raise the possibility of the existence of myosin isoenzymes in the brain. Brain myosin formed bipolar thick filaments in 0.075 M KC1 and MgCl2. At low ionic strength, the Mg2+‐ATPase activity of myosin was stimulated 3‐ to 3.5‐fold in the presence of skeletal muscle f‐actin. Brain myosin also hydrolyzed other nucleotides; the rate of hydrolysis was ITP > ATP ∼ CTP < GTP ∼ UTP. The substrate (ATP) saturation curve in the presence of 10 mM CaCl2 and 0.6 M KC1 was complex and consisted of plateau regions. The Arrhenius plot of the Ca‐ATPase data was linear, whereas with ITPase, it was biphasic with a break occurring around 20°C.
Mass Spectrometric Analyses of Brain Synaptic Peptides Containing Taurine
Authors: Marnela Kirsi‐Marja , Timonen Maritta , Lähdesmäki Pekka 
Published: October 2006

AbstractThe structure of a number of low‐molecular‐weight acidic peptides containing taurine prepared from calf brain synaptosomes and their subcellular vesicles was studied using electron impact mass spectrometry. At least seven sequences could be identified: N‐acetylas‐partyl‐glutamyl‐taurine, N‐acetylaspartyl‐taurine, N‐ace‐tylglutamyl‐taurine, glutamyl‐taurine, aspartyl‐taurine, seryl‐glutamyl‐seryl‐taurine, and seryl‐taurine.
Concentrations of Homovanillic Acid and 5‐Hydroxyindoleacetic Acid in Cerebrospinal Fluid from Human Infants in the Perinatal Period
Authors: Silverstein Faye S. , Donn Steven , Buchanan Karen , Johnston Michael V. 
Published: October 2006

AbstractTo assess maturation of central serotonin and catecholamine pathways at birth, we measured lumbar CSF homovanillic acid (HVA) and 5‐hydroxyindoleacetic acid (5‐HIAA), stable acid metabolites of dopamine and serotonin, using HPLC with electrochemical detection. CSFs from 57 neonates (38 premature and 19 at term) and 13 infants 1–6 months old were studied. HVA levels increased with maturity (p < 0.05; ANOVA), whereas, 5‐HIAA levels were similar in all these subjects. HVA/5‐HIAA ratios increased markedly from 1 ± 0.12 in the most premature neonates to 1.98 ± 0.17 in the older infants (p < 0.01; t test). There were no sex differences for these values.