bluuebunny/crossref_metadata_2025_split huggingface dataset:
CHARACTERISTICS OF THE PURIFIED NERVE GROWTH FACTOR ANTIBODY
Authors: Nagaiah K. , Lakshmanan J. , Montgomery P. , Yuand M. W. , Guroff G. 
Published: October 2006

Abstract—Purified nerve growth factor antibody has been shown to be competent in several different systems. The material is effective in producing immunosympathectomy in young rats and in preventing the action of nerve growth factor on explants of rat superior cervical ganglia. When injected into the brain of young rats it is without effect on brain tyrosine hydroxylase activity, but appears to escape into the system and cause a reduction of tyrosine hydroxylase activity in the superior cervical ganglia. Iodinated antibody injected subcutaneously into neonatal rats does not enter the brain and does not accumulate in superior cervical ganglia, or any of the other tissues studied. The antibody prevents the retrograde transport of nerve growth factor from the anterior chamber of the eye to the superior cervical ganglion and is not itself transported.
CHARACTERIZATION OF A CALCIUM‐ACTIVATED CYTIDINE TRIPHOSPHATE PHOSPHOHYDROLASE PRESENT IN DORSAL SPINAL NERVE ROOTS
Authors: Collingridge G. L. , Keen P. 
Published: October 2006

Abstract—We report here the presence of a CTPase in rat dorsal spinal nerve roots. This is activated by Ca2+ (Km= 2.1 mM) and to a lesser extent by Mg2+. It is active at 0°C and activity is increased 2‐fold at 20°C. Substrate specificity is in the order CTP > UTP > TTP = ITP = GTP > ATP. The enzyme is totally membrane‐bound and is inactivated by 0.1% Triton X‐100. Its possible function is discussed
REGULATION OF GUANOSINE 3′,5′ CYCLIC MONOPHOSPHATE IN THE RAT PINEAL AND POSTERIOR PITUITARY GLANDS
Authors: O'Dea Robert F. , Gagnon Claude , Zatz Martin 
Published: October 2006

Abstract—Potassium and norepinephrine stimulate the accumulation of cyclic AMP and cyclic GMP in rat pineal glands and their efflux into the medium. The efflux of both cyclic nucleotides was blocked by probenecid. The accumulation and efflux of cyclic GMP, but not of cyclic AMP, depends upon the presence of intact nerve endings and extracellular calcium. The calcium‐dependent release of norepinephrine caused by veratridine was accompanied by the efflux of both cyclic AMP and cyclic GMP. In contrast, the calcium‐independent release of norepinephrine caused by tyramine was accompanied by the efflux of cyclic AMP but not cyclic GMP. Changes in cyclic GMP therefore, may be related to exocytosis from the sympathetic nerve endings in the gland. High concentrations of potassium also increased tissue levels of cyclic GMP in the posterior pituitary gland. Veratridine and potassium, but not norepinephrine, stimulated the efflux of cyclic GMP from this neurosecretory gland. Thus, the relationship between cyclic GMP and exocytosis may extend beyond sympathetic nerve endings. The enhanced accumulation of cyclic GMP in the pineal gland after potassium does not appear to be mediated by extracellular (released) norepinephrine. Desmethylimipramine blocked the norepinephrine‐stimulated changes in cyclic GMP, but not those caused by potassium. Investigation of the possible relationship between cyclic GMP and release of neurotransmitters is complicated by the apparent seasonal variation in the response of pineal cyclic GMP to potassium or norepinephrine.
ADRENAL MEDULLARY CYCLIC NUCLEOTIDE PHOSPHODIESTERASE.—REGULATORY PROPERTIES OF THREE ENZYME ACTIVITIES
Authors: Sitaramayya Ari , Campbell James A. , Siegel Frank L. 
Published: October 2006

Abstract— Cyclic nucleotide phosphodiesterase from bovine adrenal medulla was fractionated into multiple activities by two different procedures, sucrose gradient centrifugation and gel filtration. Extracts of frozen and thawed adrenal medulla homogenates gave two phosphodiesterase activity peaks following density gradient centrifugation. The higher molecular weight activity hydrolyzed both cyclic AMP and cyclic GMP; ethylene glycol‐bis(aminoethyl ether)‐N,N′‐tetraacetic acid (EGTA) inhibited only the hydrolysis of cyclic GMP. The lower molecular weight activity hydrolyzed only cyclic AMP and was not inhibited by EGTA. The two activities were not interconverted by recentrifugation.Gel filtration of cyclic nucleotide phosphodiesterase activity extracted from frozen and thawed adrenal medulla on Ultrogel AcA 34 resolved the enzyme into three distinct peaks of enzyme activity with molecular weights of 350,000 (Peak I), 229,000 (Peak II) and 162,000 (Peak III). The enzyme from fresh tissue was resolved into peak I and II and only a small fraction of Peak III. Peak I hydrolyzed both cyclic nucleotides, while peak II was a cyclic GMP‐specific enzyme and peak III was specific for cyclic AMP. The hydrolysis of cyclic AMP by the activity in Peak I was markedly stimulated by cyclic GMP; the hydrolysis of cyclic GMP by peak II was inhibited by EGTA and stimulated by calcium and CDR (calcium‐dependent regulator protein). Peak III, which appears to be particulate, is not activated by either cyclic GMP or calcium and CDR.
A SENSITIVE FLUOROMETRIC METHOD FOR THE ESTIMATION OF 3,4‐DIHYDROXYPHENYLETHYLENE GLYCOL SULPHATE IN BRAIN TISSUE
Authors: Karasawa T. , Furukawa K. , Shimizu M. 
Published: October 2006

Abstract— A simple fluorometric method for the estimation of endogenous 3,4‐dihydroxyphenylethylene glycol sulphate (DOPEG‐SO4) in brain tissue is described. DOPEG‐SO4 was extracted from brain tissue with 0.4 n‐perchloric acid and purified by column chromatography on QAE‐Sephadex A‐25, Cl− form. The isolated DOPEG‐SO4 was hydrolysed by incubation with a purified preparation of sulphatase from Helix pomatia. The free DOPEG thus formed was further purified on a column of aluminium oxide and determined fluorometrically after conversion to a fluorescent compound by condensation with ethylenediamine.The sensitivity of this method was about 15 ng per perchloric acid extract applied on the column (3 ml) and the reproducibility was excellent, with a variation coefficient of 1.6% (n = 5). The concentration of DOPEG‐SO4 in whole brains of rats, determined by the present method, was 79.3 ± 4.7 ng/g (mean ± S.D., n = 10) in terms of free DOPEG. No appreciable DOPEG‐SO, was detected in the brains of mice and guinea‐pigs.
KINETICS OF [3H]ACETYLCHOLINE SYNTHESIS AND RELEASE IN PRIMARY CELL CULTURES FROM MAMMALIAN CNS
Authors: Bigalke H. , Dimpfel W. 
Published: October 2006

Abstract— The present study was undertaken to characterize the cholinergic system of primary cell cultures of mouse and rat CNS.In confirmation of previous reports, primary cultures were found to contain choline acetyltransferase (ChAc). Furthermore they contain acetylcholine (ACh) as measured by two different bioassays. They also synthesize [3H]ACh from [3H]Choline offered to the cultures.The formation of [3H]ACh is inhibited in the presence of hemicholinium‐3 (10−6m) to 50% or ouabain (10−3m) to 20% of the values found in untreated cultures. Omission of Na + from the incubation solution also diminishes the [3H]ACh formation of the cells.[3H]ACh is released upon depolarisation by K+ ions in a concentration dependent manner. The release can be prevented by lack of Ca2+ ions in the incubation solution.
A THIOL PROTEINASE HIGHLY ELEVATED IN AND AROUND THE PLAQUES OF MULTIPLE SCLEROSIS
Authors: Hirsch H. E. , Parks M. E. 
Published: October 2006

Abstract—A thiol dependent proteolytic enzyme (tentatively identified as carboxypeptidase B) which liberates phenylalanine from CBZ‐glutamyl‐phenylalanine at pH 5.3 was shown, by a sensitive micromethod, to be greatly increased in activity in and around MS plaques. These increases exceeded those of other hydrolases previously measured. Plaque tissue, on the basis of lipid‐free dry weight, is up to 3‐fold richer in this enzyme than control white matter, and most samples of apparently uninvolved MS white matter already show elevated activities. The enzyme is highly dependent on the presence of dithiothreitol. It is unaffected by diisopropyl fluorophosphate and pepstatin, but inhibited by iodoacetate and leupeptin. Macrophages or lymphocytic infiltrations in the tissue do not appear to be the main source of the enzyme.In conjunction with measurements of DNA, reflecting gliosis, invasion by hematogenom cells and proliferation of phagocytes as well as oligodendrocyte loss, and acid lipase‐esterase, indicative of the survival or degeneration of oligodendrocytes, these results are interpreted as probably reflecting predominantly the activity of astrocytes. The incidental finding that most samples of unaffected white matter from MS patients contain more DNA per unit lipid free dry weight than average control white matter is considered significant in pointing to more widespread tissue changes independent of or preceding plaque formation.
THE INTERACTIONS OF CHOLINE MUSTARD AZIRIDINIUM ION WITH CHOLINE ACETYLTRANSFERASE (EC 2.3.1.6)
Authors: Rylett B. Jane , Colhoun E. Howard 
Published: October 2006

Abstract—The nitrogen mustard analogue of choline, choline mustard aziridinium ion, was studied as a substrate and inhibitor of choline acetyltransferase in crude homogenates of rat brain. The compound was acetylated at a maximum velocity (Vmax) of 1.51±0.33μmol/g tissue/h with an apparent Km of 4.63± 0.17 mM. The Vmax for choline was 5.25±0.15μmol/g tissue/h with a Km of 1.70±0.17mM indicating that the affinity and rate of acetylation of choline mustard aziridinium ion was about 3 times less. Choline mustard aziridinium ion was a competitive inhibitor of choline acetyltransferase with a Ki of 1.8 mM. The generation of aziridiniurn ion from acetylcholine mustard was determined at 25°C and the concentration of ion in aqueous solution was inversely related to the concentration or acetylcholine mustard; the optimum ion concentration of 70% was obtained at 10 mg acetylcholine mustard/ml solution. The ineffective generation of aziridiniurn ion at high concentrations of acetylcholine mustard placed limitations on the design and evaluation of the kinetic experiments with choline acetyltransferase. Nevertheless, the present experiments demonstrate that choline mustard aziridrnium ion interacts with choline acetyltransferase and they may provide evidence for a clearer understanding in the in vivo actions of certain nigrogen mustard analogues.
VULNERABILITY OF THE IMMATURE BRAIN TO PHENYLACETATE INTOXICATION: TISSUE PERMEABILITY TO PHENYLACETATE
Authors: Loo Y. H. , Fulton T. , Wisniewski H. M. 
Published: October 2006

AbstractIn the rat phenylacetate readily penetrates into such tissues as brain, eyes, heart, kidneys, and liver. One hour after the subcutaneous injection of sodium phenylacetate into rats ranging in age from 1 to 65 days, the ratios of the concentrations (μmolig) in blood/tissue were approx 1:1 in all of these tissues with the exception of the brain. The blood‐brain ratio changed from 1:1 in the 1–7 day old rat to the adult ratio of 2:1 at 21 days of age. The free access of phenylacetate into the immature brain is especially relevant to phenylketonuria, a metabolic disease in which excessive amounts of phenylacetate are produced in peripheral tissues.
DISAGGREGATION OF POLYSOMES IN FETAL ORGANS AND MATERNAL BRAIN AFTER ADMINISTRATION OF d‐LYSERGIC ACID DIETHYLAMIDE IN VIVO
Authors: Heikkila John J. , Holbrook Larry , Brown Ian R. 
Published: October 2006

AbstractThe intravenous administration of d‐lysergic acid diethylamide (LSD) to pregnant female rabbits induced hyperthermia as well as disaggregation of polysomes in fetal organs and maternal brain. The LSD‐induced polysome shift in maternal brain and fetal organs was not due to an activation of ribonuclease or associated with alterations in the levels of free amino acids. Pretreatment with the receptor blocking agents haloperidol and pizotyline blocked both LSD‐induced polysome shift in maternal brain and fetal organs and LSD‐induced hyperthermia. Fine dissection of adult rabbit brain showed that the extent of LSD‐induced disaggregation of polysomes does not exhibit any marked regional variation.
THE CHEMICAL COMPOSITION OF MYELIN IN ORGAN CULTURES OF RAT CEREBELLUM
Authors: Bradbury K. , Lumsden C. E. 
Published: October 2006

AbstractMyelinating organ cultures of rat cerebellum were maintained in vitro for up to 130 days. Extensive myelination took place between 7 DIV (days in vitro) and 28 DIV. Centrifugation of a crude culture myelin fraction on a discontinuous gradient yielded three layers termed light myelin, heavy myelin and membrane fraction, which exhibited an ultrastructure virtually identical to that of comparable layers prepared from surviving littermates. However, culture myelin layers showed a gross deficiency of galactolipids with a relative increase in phospholipids. The 2,3′‐cyclic nucleoside‐monophosphate phosphodiesterase (CNP) activity was decreased in the culture myelin layers, but not to an extent comparable to the cerebroside deficiency. A form of “slow myelin maturation” takes place in vitro with both myelin cerebrosides and sulphatides increasing in cultures older than 60 DIV. The results indicate that CNS myelination comprises at least two phases, and that the second phase involving galactolipid enrichment of myelin can, under experimental conditions, be partly uncoupled from the first phase without affecting the morphology or ultrastructure of the sheaths.
PROTEIN PHOSPHORYLATION IN SYNAPTIC MEMBRANES REGULATED BY ADENOSINE 3′:5′‐MONOPHOSPHATE: REGIONAL AND SUBCELLULAR DISTRIBUTION OF THE ENDOGENOUS SUBSTRATES
Authors: De Blas Angel Luis , Wang Yng‐Jiin , Sorensen Roger , Mahler Henry R. 
Published: October 2006

Abstract— The aim of these studies is the determination of the topographic distribution of the endogenous substrates in synaptic membrane preparations susceptible to phosphorylation in reactions modulated by adenosine 3′:5′‐monophosphate or Ca2+. To this end we have investigated the distribution of these phosphosubstrates in different cellular and synaptic subfractions obtained from rat cortex and corpus striatum, in other rat brain regions and in bovine retina, as well as membrane fractions from liver and testis.The results obtained indicate that two cAMP‐dependent protein substrates B (p80, i.e. apparent MR= 80,000) and C (p75) are, as originally suggested by Greencard and collaborators confined to nerve tissue; they are located at least in part in the postsynaptic density, as is an additional protein D (p66). This localization appears to be shared by a cAMP‐dependent, and a cAMP‐independent entity, designated E (p54) and p48, respectively. In contrast, at least one prominent protein substrate requiring cAMP for its phosphorylation, component F (p50), appears to be associated predominantly with the postsynaptic membrane.At least two of these cAMP‐dependent (B and C), as well as two Ca2+ ‐dependent (p63 and p59), phosphoproteins appear to be associated with the presynaptic membrane.
IDENTIFICATION OF A GROUP OF OCTOPUS BRAIN PROTEINS AS HISTONES
Authors: Cimarra Patrizia , Giuditta Antonio 
Published: October 2006

Abstract— We have investigated the subcellular localization of a group of proteins solubilized with SDS from saline‐washed particulates of octopus brain and identified as the most rapidly moving species in SDS‐gel electrophoresis. These proteins are several‐fold more concentrated in the vertical and optic lobes than in the suboesophageal lobe. In the optic lobe their concentration decreases with increasing body weight (Giudittaet al, 1975).Upon separation of hypertonic sucrose homogenates from the optic lobe in a nuclear pellet and in a floating layer containing cytoplasmic particulates, the proteins appear associated with the nuclear fraction. Differential extraction of the latter fraction shows that the proteins have the same solubility and electrophoretic mobilities as histones. Proteins with similar properties are present in other brain regions and in non‐nervous organs.
CYTOSOLIC GANGLIOSIDES: OCCURRENCE IN CALF BRAIN AS GANGLIOSIDE‐PROTEIN COMPLEXES
Authors: Sonnino Sandro , Ghidoni Riccardo , Marchesini Sergio , Tettamanti Guido 
Published: October 2006

Abstract—Calf brain was treated in order to prepare separately the cytosol from neuronal bodies and glial cells, and the cytosol from nerve endings. The first cytosol contained 29 μg of ganglioside bound sialic acid/g fresh tissue, the latter 3.1 μg. Upon addition of ammonium sulphate until saturation the gangliosides contained in the two cytosols precipitated and were totally recovered in the pellet. while, under the same conditions, pure gangliosides were completely soluble. After stepwise ammonium sulphate fractionation all the different fractions obtained contained gangliosides and carried an approximately constant ganglioside/protein ratio. Thus cytosolic gangliosides occur in calf brain as ganglioside‐protein complexes.The qualitative and quantitative pattern of gangliosides appeared to be similar in the two cytosols and in the different ammonium sulphate fractions obtained from the same cytosols. In addition, the pattern of cytosolic gangliosides was similar to that of membrane bound gangliosides.
DIFFERENTIAL ENRICHMENT OF CELLS FROM EMBRYONIC RAT CEREBRA BY CENTRIFUGAL ELUTRIATION
Authors: Schengrund Cara‐Lynne , Repman Mary Ann 
Published: October 2006

Abstract—Centrifugal elutriation was used to obtain different populations of cells dissociated from 16‐day‐old rat embryo cerebra. The cell populations recovered were viable and could be maintained for several weeks in vitro. Sterile conditions were maintained throughout a preparation. Rat pups were removed by Caesarean section, the cerebra dissected and the cells dissociated by brief exposure to trypsin (0.125%, 6 min). An equivalent volume of elutriation medium (Dulbecco's medium containing 1% fetal calf serum, sodium bicarbonate, penicillin and streptomycin, EDTA, and deoxyribonuclease) was added to the trypsin‐cell suspension, the dissociated cells pelleted, resuspended in elutriation medium and counted. Up to 4 x 108 cells were injected into the previously sterilized elutriator. Seven fractions were usually recovered from a preparation. The first fraction contained primarily red blood cells and cell debris, which could not be maintained in vitro. Upon culture, fraction 2 consisted of predominantly non‐neuronal cells, while fractions 3–6 contained neuronal and non‐neuronal cells. The morphological characteristics of the neurons differed in these fractions. Fraction 7 contained cells that had reaggregated during the elutriation procedure and exhibited a variety of cell types in vitro.
Ca2+‐ or Mg2+‐Dependent Enzymic ATP Hydrolysis Associated with the Microsomal Fraction of Frog Sciatic Nerves
Authors: Edström Anders , Hanson Mats , Prus Karen , Wallin Margareta 
Published: October 2006

AbstractThe microsomal fraction of frog sciatic nerves was found to contain Ca2+‐ or Mg2+‐dependent hydrolytic activity toward different nucleoside di‐and triphosphates. In the presence of Ca2+ substrate specificity was in the order CTP > UTP > GTP > ATP. When Mg2+ was used, the triphosphates were approximately equally good substrates. ATP hydrolytic activity was very similar with Ca2+ or Mg2+ as the cofactor, whereas Ca2+ was the more potent activator of hydrolysis of the other triphosphates tested. The preparation showed some activity toward the nucleoside diphosphates but none toward the monophosphates or p‐nitrophenylphosphate. The enzymic properties of ATP hydrolysis were more closely studied. The hydrolysis was optimal at 18–24°C in the presence of 1 mm‐Ca2+ or 1 mm‐Mg2+. Ca2+‐ and Mg2+‐ATP hydrolysis displayed pH maxima around 8.0–8.5 and 7.4–8.0, respectively. Vmax values for Ca2+‐ and Mg2+‐ATP hydrolysis were similar: approx. 12 μmol Pi per h per mg protein with a Km value of approx. 0.05 mm. The ATP hydrolysis activity was inhibited by NaF but unaffected by ouabain, vanadate, cytochalasin B, and various drugs known to influence ATPase activity of mitochondria. Zn2+ stimulated the ATP hydrolysis activity at low concentrations (10‐6–10‐5m) and inhibited it at higher concentrations. The possibility that these observations account for stimulation and inhibition of axonal transport in frog sciatic nerves exposed to similar concentrations of Zn2+ is discussed.
Activation and Inhibition of Cerebral Prolidase
Authors: Hui Koon‐Sea , Lajtha Abel 
Published: October 2006

AbstractPurification of prolidase from calf brain (acetone and [NH4]2SO4 fractionation) separated this enzyme from proteases, leucine aminopeptidase, master dipeptidase, and Gly‐Gly dipeptidase. Prolidase was tested with peptidase and protease inhibitors, used at higher levels (35 times or more) than their ID50 for peptidases and proteases. Bacitracin, leupeptin, chymostatin, and antipain had no effect; pepstatin slightly increased activity, and only bestatin was inhibitory. Antibiotics that affect protein synthesis did not inhibit prolidase. Peptides with proline at the NH2 end activated prolidase, whereas those with proline at the carboxyl end inhibited it. Di, tri, and tetra‐Pro peptides increased prolidase activity. Thyrotropin‐releasing hormone had no effect on prolidase; its analog Pro‐His‐Pro‐NH2 gave high activation and decreased the Km from 20 mm to 1.54 mm. Pro‐peptide inhibitors and activators were not themselves split by prolidase. The results indicate influences of specific peptides, for both inhibition and activation, on prolidase activity.
Incorporation of Choline and Inositol into Phospholipids of Isolated Bovine Oligodendrocyte Perikarya
Authors: Brammer M. J. , Carey S. G. 
Published: October 2006

Abstract:Oligodendrocyte perikarya have been prepared from fresh and frozen bovine corpus callosum by a slight modification of previously published methods. The properties of the cells which we have obtained appear to be very similar to those previously described in other laboratories. Oligodendrocyte homogenates have been incubated with radioactive choline and inositol in the presence of a number of possible cofactors of phospholipid synthesis. Choline was incorporated into oligodendrocyte phosphatidylcholine both by synthesis de novo and by Ca2+‐simulated base exchange. There was no detectable incorporation of choline into sphingomyelin by either of these routes. Inositol was incorporated into oligodendrocyte phosphatidylinositol by synthesis de novo and by Mn2‐‐stimulated exchange. Oligodendrocyte homogenates were found to contain sufficient endogenous Cat2+ both to stimulate significant incorporation of choline into lecithin by base exchange and to produce considerable inhibition of lecithin synthesis de nova.Brammer M. J. and Carey S. G. Incorporation of choline and inositol into phospholipids of isolated bovine oligodendrocyte perikarya. J. Neurochem.35, 873–879 (1980).