bluuebunny/crossref_metadata_2025 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.
AROMATIC AMINOTRANSFERASE ACTIVITY OF RAT BRAIN CYTOPLASMIC AND MITOCHONDRIAL ASPARTATE AMINOTRANSFERASES
Authors: King Stephen , Phillips Allen T.
Published: October 2006

Abstract—Mitochondrial and cytoplasmic forms of aspartate aminotransferase were purified from rat brain homogenates and tested for their ability to catalyze transamination of various aromatic amino acids. The mitochondrial enzyme exhibited activity toward tyrosine and phenylalanine with 2‐oxoglutar‐ate as acceptor, although the specific activities were less than 1% of the corresponding aspartate activity when all substrates were 10 mM. Even less activity was seen with DOPA, 5‐hydroxytryptophan and tryptophan. The cytoplasmic aspartate aminotransferase was active toward tryptophan, 5‐hydroxytryptophan and DOPA, but these transaminations were favored by pyruvate or oxaloacetate rather than 2‐oxoglutarate as keto acid. Based on co‐migration of aromatic activities with the respective aspartate aminotransferases during isoelectric focusing and based on equal sensitivities of aromatic transamination and aspartate transamination to inhibition by vinylglycine, it was concluded that all activities resided in the aspartate aminotransferase enzymes. Some doubt exists, however, as to the physiological significance of these alternate activities in view of the requirement that aromatic amino acids must compete with aspartate for transamination by these enzymes.
ELEVATION OF 7‐AMINOBUTYRYLCHOLINE CONTENT IN CAT CEREBRAL CORTEX BY ELECTRICAL STIMULATION OF AFFERENT NERVES
Authors: Lichtshtein D. , Dobkin J.
Published: October 2006

Abstract—A method for the separation and determination of γ‐aminobutyrylcholine (GABACh) from trichloracetic acid treated brain extracts has been developed. It consists of the separation of the extracts on Dowex 1 × 8 columns, precipitation of the quaternary ammonium bases and their separation by paper chromatography. Using this technique it was found that electrical stimulation for 30 s of one brachial plexus in the cat resulted in 4.6 fold increase in GABACh concentration in the stimulated (contralateral) cerebral cortex as compared to the non‐stimulated (ipsilateral) cortex. This change in GABACh concentration was not reversed within 5 s of cessation of the stimulus. The results are discussed in relation to the possible physiological role of GABACh: (a) as a neurotransmitter; (b) as a substance participating in the inactivation process of GABA. The possible connection of GABACh to the metabolism of GABA and acetylcholine is discussed.
IDENTIFICATION AND QUANTIFICATION OF 3‐METHOXY‐4‐HYDROXYPHENYLETHANOL (MOPET) IN HUMAN CEREBROSPINAL FLUID AND RAT BRAIN BY MEANS OF GAS CHROMATOGRAPHY‐MASS SPECTROMETRY
Authors: Muskeit Frits A. J. , Jeuring Hans J. , Adégr J.‐P. , Wolthers Bert G.
Published: October 2006

Abstract— The identification of 3‐methoxy‐4‐hydroxyphenylethanol (MOPET) in human cerebrospinal fluid and in rat brain is described. Use was made of the high sensitivity and selectivity provided by gas chromatography‐mass spectrometry. Concentrations of MOPET in human cerebrospinal fluid, rat brain and rat urine together with those of some other catecholamine metabolites are given. The effect of intraperitoneal administration of deuterium‐labelled MOPET and haloperidol on rat brain and urine MOPET levels was studied. The quantitative importance of MOPET as an end product of central and peripheral dopamine metabolism in man and rat is discussed.
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.
THE SELECTIVE NEURONAL UPTAKE AND RELEASE OF [3H]DL‐2,4‐DIAMINOBUTYRIC ACID BY RAT CEREBRAL CORTEX
Authors: Weitsch‐Dick F. , Jessell T. M. , Kelly J. S.
Published: October 2006

Abstract— At 25°C the accumulation of [3H]dl‐2,4‐diaminobutyric acid (DABA) into small rat cortical slices was linear with time and a tissue: medium ratio of 35:1 was attained after 60 min. At 37°C the uptake was no longer linear and the tissue: medium ratio at 60 min was 66:1. Uptake was unaffected by the addition of 10 μm‐AOAA and dependent on the presence of Na+ in the incubation media. The uptake was shown to have a high affinity component with a Km of 20.7 μm and a Vmax of 28.6 nmol/g/min. IC50's for the inhibition of [3H]DABA uptake by dl‐DABA, l‐DABA and GABA were 80, 40 and 17 μm respectively. Two mmβ‐alanine, however, caused less than 13% inhibition of [3H]DABA uptake. Electron microscopic autoradiographs showed the [3H]DABA to be accumulated by 22% of the identifiable nerve terminals and, after 14 days exposure, the density of silver grains over nerve terminals was 36–38 times higher than that over the rest of the electron micrograph. On the other hand, [3H]DABA was not taken up into rat sensory ganglia and light level autoradiography showed the small amount of [3H]DABA accumulated by the ganglia to be evenly distributed throughout the tissue. Both electrical stimulation for 30 s and exposure of the tissue to a medium containing 47 mm‐K+ for 2 min caused a marked increase in the efflux of [3H]DABA from the tissue. Both these effects were abolished by a reduction in Ca2+ concentration and an increase in the Mg2+ concentration of the superfusing medium. These results suggest that l‐DABA acts as a ‘false transmitter’ for the neuronal uptake, storage and release of GABA.
DNA OF BROMODEOXYURIDINE–TREATED NEUROBLASTOMA CELLS
Authors: Wintzerit M. , Dieric A. , Treska J. Ciesielsk , Mande P.
Published: October 2006

Abstract— Cells of an adrenergic clone M1 of the mouse neuroblastoma C 1300 show morphological differentiation when treated with BrdU (10−5m). The involvement in this phenomenon of an action of BrdU at the membrane level has been suggested (see References). Taking into account the alterations observed after addition of BrdU in culture cell lines it was interesting to investigate the incorporation of BrdU into DNA of neuroblastoma cells. Our results showed an active BrdU incorporation into the DNA of treated Ml cells (an average of 25% of all thymidine residues for the 10−5m‐BrdU concentration present in our experimental conditions). Thymidine substitution by BrdU did not occur randomly, indicating the existence of selective parts in the genome sensitive toward BrdU. In mitomycin–treated cells (at high doses) BrdU incorporation occurred significantly at a very low level when related to the total thymidines (2%). Our findings suggest that since DNA synthesis is not inhibited BrdU may act by being incorporated into DNA and thus altering gene expression in addition to a site of action on the cell membranes.
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

In 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

The 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

Myelinating 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.
STUDIES ON HAEM BIOSYNTHESIS IN RAT BRAIN
Authors: Percy V. A. , Shanley B. C.
Published: October 2006

Abstract— Abnormalities involving haem biosynthesis have been postulated as underlying mechanisms in the aetiology of the neural manifestations of acute porphyria and of lead poisoning. This paper reports a study of the enzymes of the haem biosynthetic pathway and their control in mammalian brain. The activity of rat brain 6‐aminolaevulinate synthetase (ALA synthetase), 6‐aminolaevulinate dehydratase (ALA dehydratase), uroporphyrinogen I synthetase, uroporphyrinogen decarboxylase and ferrochelatase were found to be between 12.5 and 0.002% of the corresponding values for liver. This accords with the lower concentrations of total haem and cytochrome P450 found in brain and with the slower rate of incorporation of [4‐14C]ALA into brain haem in vivo. The subcellular distribution of radioactivity following intraventricular injection of [4‐14C]ALA confirmed that the bulk of brain haemoproteins are intramitochondrial in contrast to liver where the major portion is microsomal. Brain haem biosynthesis was apparently unaffected by factors known to influence this pathway in liver, including starvation and treatment with allylisopropylacetamide or phenobarbitone. These findings suggest that brain haem requirements are considerably less than those of liver and are not subject to significant fluctuations under normal circumstances. Apparent non‐inducibility of ALA synthetase suggests that deficient haem and consequently haemoprotein production could result where other enzymes in the pathway become rate‐limiting due to genetic defects or inhibition by exogenous agents such as lead.
UPTAKE AND RELEASE OF EXOGENOUS [1‐14C]ACETYLCHOLINE BY BRAIN CORTEX SLICES FROM THE RAT
Authors: Grewaal D. S. , Quastel J. H.
Published: October 2006

Abstract— Radioactive acetylcholine ([14C]ACh) that is taken up by rat cerebral cortex slices, incubated aerobically in a physiological saline‐glucose paraoxon‐[14C]ACh medium, apparently by a passive diffusion process at concentrations > 1 mm consists essentially of two forms, a readily exchangeable and releaseable or mobile form, and a bound or retained form, poorly (or not) exchangeable. The quantity of retained ACh consists of a considerable fraction of that taken up amounting to 54% with external 0.1 mm‐[14C]ACh and about constant, 27%, for the range 5‐50mm‐[14C]ACh. All its ACh is released on homogenization with 0.1 n‐perchloric acid or on tissue disintegration in distilled water. The cerebral uptake of ACh differs basically from that of urea as there is no retention of the latter following its uptake. Cerebral cortex slices are superior to those of cerebellar cortex, subcortical white matter, kidney cortex, liver and spleen in taking up and retaining [14C]ACh. Deprivation in the incubation media of glucose or Na+ or Ca2+. or the presence of dinitrophenol, whilst causing little change in ACh uptake, induces considerable changes in swelling and ACh retention; the greater the amount of swelling the smaller is that of retention. It seems that the latter is segregated in compartments characterized by a low permeability to exogenous ACh. About half of it is independent of changes in incubation conditions whilst the other half enters the compartment by an Na+, Ca2+ and energy‐dependent process. At least part of the retention is neuronal as it is diminished by protovera‐trine, the diminution being blocked by tetrodotoxin. Mobile ACh (i.e. total uptake minus retained ACh) is largely unaffected by protoveratrine, ouabain, etc. It seems that the retained ACh is directly proportional to the amount of mobile ACh minus the amount that enters with swelling. If the latter is largely glial in location, then the retained ACh is simply proportional to the mobile neuronal ACh. Suggestions are made as to the location of the retained ACh in the brain cells and to the processes involved in its segregation there. Release of retained ACh occurs on change of the Na+ gradient. Atropine and d‐tubocurarine also diminish the amount of retained ACh but the percentage diminution falls with increase of the concentration of exogenous ACh.
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.
BREAKDOWN OF CREATINE PHOSPHATE AND ATP IN NERVE TERMINALS AND ELECTROPLAQUES OF THE TORPEDO ELECTRIC ORGAN: COMPARISON WITH THE ELECTRICAL ENERGY DISSIPATED
Authors: Chmouliovsky‐Moghissi M. , Dunant Y.
Published: October 2006

Abstract— The electrical work performed by the electric organ of Torpedo was compared with the energy provided by the net breakdown of ATP and creatine phosphate (CrP). The electrical work was calculated for single impulses and for repetitive stimulations. The content in CrP and ATP was measured at different times in the course of stimulation and during the period of recovery. The chemical expenditure due to activity of the nerve terminals was distinguished from the total expenditure by the use of curare which interrupts synaptic transmission but does not interfere to any great extent with the release of acetylcholine. In the presence of curare the breakdown of phosphagen started only after more than 1 min of stimulation; it represented the loss of about 20‐25% of the initial store. In untreated tissue the breakdown of CrP and ATP occurred in two phases and continued within the first minute after the end of the stimulation; as much as 77% of the phosphagen content was utilized under these conditions. The recovery of ATP and CrP was completed only 3‐5 h after stimulation, a long time after the restoration of the physical capabilities of the tissue. The electrical energy dissipated during activity was smaller than the chemical energy provided by the net breakdown of phosphagens. This suggests that only a fraction of the chemical energy is utilized directly to compensate for the physical work accomplished, i.e. for the restoration of the ionic electromotive force. The electric organ also requires chemical energy for other purposes, particularly in the nerve endings where the presynaptic machinery seems to utilize an important fraction of the high energy phosphates stored in the tissue.
LOW CONCENTRATIONS OF LITHIUM INHIBIT THE SYNTHESIS OF CYCLIC AMP AND CYCLIC GMP IN THE RAT PINEAL GLAND
Authors: Zatz Martin
Published: October 2006

Abstract— Lithium chloride (2 mm) significantly inhibited the increases in cyclic AMP and in cyclic GMP caused by norepinephrine or high concentrations of potassium in intact rat pineal glands. Adenylyl cyclase activity in homogenates and its stimulation by isoproterenol, a β‐adrenergic agonist, were also inhibited. Lithium reduced the apparent Vmax of isoproterenol‐stimulated adenylyl cyclase activity without significantly affecting the apparent affinity for isoproterenol. There was no effect on the binding of the antagonist [3H]dihydroalprenolol to the β‐adrenergic receptors, nor on the competition for binding sites by isoproterenol. Inhibition of adenylyl cyclase activity by lithium was inversely related to the magnesium concentration in the reaction mixture. There was no differential effect of lithium on adenylyl cyclase activity from supersensitive vs subsensitive glands. Lithium may inhibit cyclic nucleotide synthesis by interfering with the role of divalent cations.
THE INFLUENCE OF SECRETIN, GLUCAGON AND OTHER PEPTIDES, OF AMINO ACIDS, PROSTAGLANDIN ENDOPEROXIDE ANALOGUES AND DIAZEPAM ON THE LEVEL OF ADENOSINE 3′,5′‐CYCLIC MONOPHOSPHATE IN NEUROBLASTOMA GLIOMA HYBRID CELLS
Authors: Propst Friedrich , Moroder Luis , Wuunsch Erich , Hamprecht Bernd
Published: October 2006

Abstract— Neuroblastoma glioma hybrid cells display many properties of neurons. A series of compounds, among them a number of amino acids, peptides and peptide hormones were tested for their ability to influence the level of adenosine 3′,5′‐cyclic monophosphate (cyclic AMP) in the hybrid cells. Two prostaglandin endoperoxide analogues exhibit a weak stimulatory action, if applied in at least micromolar concentrations. At nanomolar concentrations, only the gastrointestinal hormones secretin and glucagon stimulate the formation of cyclic AMP, as detected in the presence of a phosphodiesterase inhibitor. The effect of secretin but not that of glucagon is antagonized by secretin‐(5–27), suggesting that secretin and glucagon act on the cells via different receptors. These results appear to be noteworthy since (a) an effect of secretin or glucagon on a cell with neuronal characteristics has not yet been described, and (b) many peptide hormones have been detected both in the gastrointestinal tract and the nervous system.
THE IRREVERSIBLE INHIBITION OF BRAIN L‐GLUTAMATE‐I‐DECARBOXYLASE BY (2RS,3E)‐2‐METHYL‐3,4‐DIDEHYDROGLUTAMIC ACID
Authors: Chrystal Ewan , Bey Philippe , Rando Robert R.
Published: October 2006

Abstract— Incubation of chick embryo brain l‐glutamate‐1‐dccarboxylase (GAD, EC 4.1.1.15) with (2RS,3E)‐2‐methyl‐3,4‐didehydroglutamic acid (MDG), a substrate analog of l‐glutamic acid, results in a time‐dependent irreversible inhibition of the enzymic activity. In the presence of 2.0 ± 10‐3m inhibitor the half‐life for inactivation is 11.6min. The inhibitor is a substrate for GAD and requires turnover prior to inactivating the enzyme and is therefore another example of the kcat class of inactivator. The measured Kl is 6.6 ± 10‐4m and the kcat for its turnover is 1.01 ± 10‐3 s‐1 at 37°C (pH 7.2). The inhibitor has no effect on the apoenzymc or the holoenzyme treated with 1.0 ± 10‐3m hydrazinc. Both l‐and d‐glutamate, but not mercaptoethanol, reduce the rate of enzymie inactivation by the inhibitor. The exceedingly high specificity implicit in the design of this inhibitor should render it useful in studies designed to uncover the physiological role of GABA.
THE PURIFICATION AND PROPERTIES OF PIG BRAIN CATECHOL‐o‐METHYLTRANSFERASE
Authors: Gulliver Peter A. , Tipton Keith F.
Published: October 2006

Abstract— The previously reported affinity chromatography technique (Gulliver & Tipton, 1978b) has been adapted for the large‐scale purification of pig brain catechol‐o‐methyltransfcrase. The enzyme prepared by this method is apparently homogeneous by polyacrylamide gel electrophoresis criteria and is stable for prolonged periods of storage at—5°C in 20% (v/v) glycerol. Kinetic measurements, molecular weight criteria and antiserum reaction suggest that the brain and liver forms of catechol‐o‐methyltransferase are very closely related, if not identical.
TWO FORMS OF ALANINE AMINOTRANSFERASE IN RAT BRAIN DURING ONTOGENY
Authors: Orlick J. , Ruščák M. , Ruščáková D. , Hager H.
Published: October 2006

Abstract— Alanine aminotransferase activity in subcellular fractions of rat brains was investigated during ontogenic development. The activity rose from the prenatal period until adulthood, the highest increase being observed during the period of morphological metabolic and functional maturation of the brain. The rise of the total activity was due predominantly to a rise in the activity of the cytosblic enzyme; the activity of the mitochondrial enzyme did not change markedly during ontogeny. CI‐ions and elevated temperature (55°C) inhibited the activity only of the mitochondrial enzyme. Raised temperature stimulated the activity of the cytosolic enzyme while CI‐ions did not influence its activity. Our results indicate that 2 alanine aminotransferase isoenzlmes are already present in the rat brain in the prenatal period. It is assumed that the cytosolic enzyme is involved in the regulation of tissue glycol)sis and alanine formation, while the mitochondrial enzyme plays a role in the amino nitrogen transport between mitochondria and cytosol.
CYTOSOLIC GANGLIOSIDES: OCCURRENCE IN CALF BRAIN AS GANGLIOSIDE‐PROTEIN COMPLEXES
Authors: Sonnino Sandro , Ghidoni Riccardo , Marchesini Sergio , Tettamanti Guido
Published: October 2006

—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

—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

The 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

Purification 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

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).
Cerebellar Hypoplasia in the Gunn Rat with Hereditary Hyperbilirubinemia: Immunohistochemical and Neurochemical Studies
Authors: Mikoshiba Katsuhiko , Kohsaka Shinichi , Takamatsu Ken , Tsukada Yasuzo
Published: October 2006

Abstract: Immunohistochemical reactions were conducted, using the antibodies against GFA and S‐100 proteins on sections of cerebellum from the homozygous (jj) and the heterozygous (Jj) Gunn rats. Hypertrophy of the fibrous astrocytes was observed but hyperplasia of the glial cells was not. Although the molecular layer was very thin, the Bergmann fibre appeared normal. Among the free amino acids in the cerebellum from the jj rat, glutamate concentration decreased to two‐thirds of the control level. The protein profile of the cerebellum from the jj rat obtained by SDS‐polyacrylamide gel electrophoresis revealed that the amount of P400 protein that is characteristic of Purkinje cells decreased considerably and there were also some changes of the other unidentified proteins. By two‐dimensional electrophoresis, it was observed that in the supernatant from the jj rat cerebellum one protein spot diminished and in the particulate fraction from the jj rat one spot was enormously increased. The activity of 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase (CNPase) in the cerebellum from the jj rat did not differ significantly from that of the control; however, activities of choline acetyltransferase and acetylcholinesterase of the jj rat were about twice as high as those of the control. 2‐Deoxyglucose incorporation was maximum in the granular layer from both the jj and the Jj rat cerebella. However, the incorporation in the jj cerebellum was not higher than in the Jj control and even lower in some parts of the jj cerebellum than in the control Jj cerebellum.
Dipeptide Antagonists of Amino Acid‐Induced and Synaptic Excitation in the Frog Spinal Cord
Authors: Francis A. A. , Jones A. W. , Watkinst J. C.
Published: October 2006

Abstract: The dipeptide γ‐d‐glutamylglycine (γDGG) antagonizes amino acidinduced depolarization and synaptic excitation in the isolated hemisected spinal cord of the frog. In general, the effects of this compound resembled those of the structurally similar d‐α‐aminosuberate (DαAS) in being more effective against N‐methyl‐d‐aspartate (NMDA)‐induced responses than against responses induced by other excitatory amino acids. However γDGG appeared to be more effective than DαAS in depressing kainate‐induced responses. Similar, though weaker, effects were produced by the L isomer of the dipeptide (αLGG), a natural brain constituent.
Synthesis of Sulfatide by Cultured Rat Schwann Cells
Authors: Fryxell Karl J.
Published: October 2006

Abstract: The 35S sulfolipids synthesized by purified cultures of rat Schwann cells, fibroblasts, and a rat cell line (RN2) were studied. Schwann cell 35S sulfolipids were almost entirely [35S]sulfatide, as shown by TLC in two different solvent systems with unlabeled authentic sulfatide run in the same track. RN2 and fibroblasts did not synthesize significant amounts of sulfatide, by the same criteria. Previous studies failed to detect any characteristic myelin components, including sulfatide, on Schwann cells after several days in culture (Brockes et al., 1980a; Mirsky et at., 1980). My results show that Schwann cells continue to synthesize some sulfatide in the absence of neurons.
Neuronal and Extraneuronal Effects of Intracisternally Administered 6‐Hydroxydopamine on the Developing Rat Brain
Authors: Sievers J. , Klemm H. P. , Jenner S. , Baumgarten H. G. , Berry M.
Published: October 2006

Abstract: Intracisternal administration of 100 μg 6‐OHDA to newborn rats causes permanent defects, not only of the monoaminergic neuron system, but also of extraneuronal tissue elements. The long noradrenergic fibre tracts are irreversibly destroyed, while the short projections recover and regenerate after a transient period of injury. In the major noradrenergic cell group, the locus coeruleus, most of the cells in the caudal and middle parts degenerate, while a small dorsorostral group survives and forms the source of the regenerating fibres. Dopaminergic and serotonergic fibre tracts are also affected. The 6‐OHDA treatment also damages granule and dial cells of the cerebellar cortex as well as the mesenchymal cells of the pial coverings of the cerebellum, leading to primitive foliation, absence of fissuration, and defective migration of granule cells and resulting in a marked reduction of cerebellar size, area, and granule cell number.
Acetylcholinesterase Molecular Forms in Chick Ciliary Ganglion: Pre‐ and Postsynaptic Distribution Derived from Denervation, Axotomy, and Double Section
Authors: Couraud J. Y. , Koenig H. L. , Di Giamberardino L.
Published: October 2006

Abstract: Four main molecular forms of acetylcholinesterase (AChE) characterized by their sedimentation coefficients (5S, 7.5S, 11.5S, and 20S), are found in chick ciliary ganglion. After transection of the preganglionic nerve (denervation), total AChE activity in the ganglion dropped by 35% in 2 days. By then, 11.5s and 20s forms had diminished by 60 and 75% respectively, where as 7.5s remained practically unchanged. Since presynaptic structures disappeared 2 days after denervation, we inferred that at most 35% of total ganglion AChE was presynaptic: 11.5s and 20s might be mainly presynaptic and 7.5S, postsynaptic. At later time intervals. total AChE continued to decline up to day 5, possibly as a result of orthograde transynaptic regulation of the enzyme activity. After transection of postganglionic nerves (axotomy), total ganglion activity showed little change; 11.5s and 20s decreased by 40 and 6076, respectively, in 5 days, but these drops were compensated for by an early increase in 7 5S, which started the day after axotomy. After simultaneous transection of both pre‐ and postganglionic nerves (double section), total ganglion AChE dropped rapidly by 35% in 1 day and remained at that level up to 21 days. The 11.5S diminished rapidly by 60% in 1 day. The early increase of the 7.5s form induced by axotomy alone did not occur. Since the effect resulting from double section was not the equivalent of the cumulative effects observed after denervation and axotomy, respectively, the level of AChE forms in the ganglion may be regulated by reciprocal interaction of pre‐ and postsynaptic elements. After denervation and double section but not after axotomy alone, the contralateral non‐operated ganglion exhibited a fall in the 20s form. This suggests that a transynaptic effect is exerted on AChE by the contralateral preganglionic neuron. Taken together, these results indicate that the various AChE molecular forms in chick ciliary ganglion are preferentially but not exclusively distributed as follows: the pre‐ and postganglionic axons contain mainly the 11.5S form, whereas nerve endings and synaptic structures are enriched in 20S, and ganglion cell bodies, in 7.5s.