bluuebunny/crossref_metadata_2025_split huggingface dataset:
CORRECTION FACTORS FOR ‘BINDING’ STUDIES; MODEL SYSTEMS FOR GABA BINDING TO A SYNAPTOSOMAL–MITOCHONDRIAL FRACTION OF RAT CEREBRAL CORTEX1
Authors: Somoza E. , DeFeudis F. V. 
Published: October 2006

Abstract—Correction methods currently used in ‘binding’ experiments have been compared and a new approach is proposed. These methods have been applied to data on the ‘binding’ of GABA to a ‘synaptosomal‐mitochondrial’ fraction of rat cerebral cortex under various conditions. Results indicated that values for ‘corrected binding’ can differ greatly, depending upon the method employed. Calculations based on data obtained when using a high concentration of unlabelled GABA to displace ‘specific’ binding of [3H]GABA (‘cold ligand method’) under‐estimated the binding, because this method neglects the existence of a biochemically‐inert space which exists within the pellet even at 0°C and which traps labelled ligand. The other correction method, in which an inert labelled substance (e.g. sucrose) is used to measure the portion of the pellet occupied by trapped supernatant fluid (‘sucrose space method’), is more accurate, but does not take into account the amount of ligand that may be non‐specifically bound to the particulate portion of the pellet. The error with this method is small for ‘high‐affinity’ ligand‐receptor systems, but may be quite large for lower affinity systems. A method which takes into consideration both the inert space of the pellet and ligand that is non‐specifically bound to the pellet (‘fully corrected method’) is proposed. The three correction methods have been applied to a study of the kinetic parameters of GABA binding to a ‘synaptosomal‐mitochondrial’ fraction of rat cerebral cortex in the presence and absence of the GABA inhibitor, bicuculline‐methiodide. In some cases, the results showed qualitative as well as large quantitative differences, depending on the correction method employed.
INFLUENCES OF COLCHICINE, VINBLASTINE AND CYTOCHALASIN ON THE RELEASE OF 5‐HYDROXYTRYPTAMINE FROM RAT BRAIN SYNAPTOSOMES
Authors: Segawa T. , Murakami H. , Inouye A. , Tanaka Y. 
Published: October 2006

Abstract—Rat brain synaptosomes preincubated with [3H]5‐HT. were further incubated and the release of [3H]5‐HT from the preparation was studied. The spontaneous release consisted of an initial rapid phase followed by slower release. Incubation with 60 mM‐KCl increased the release while 60 mw‐NaCl did not affect it. The effect of KG was abolished when NaCl was omitted from the medium. The potassium‐induced release was Ca2+ ‐dependent while that induced by tyramine (10−5‐10−4M) and the spontaneous release did not depend on Ca2+. Vinblastine (10−5–2.5 X 10−4 M) caused an increase in the spontaneous release and an decrease in the potassium‐induced release, while it completely inhibited the release by tyramine at 2.5 X 10−4 M. Colchicine (5 X 10−5–10−3M) and cytochalasin D (10−5, 10−4 M) failed to produce any change in the release. Cytochalasin B (10−5, 10−4M) increased the spontaneous release and decreased the potassium‐induced release but it did not affect the release by tyramine. Colchicine (10−3 M). vinblastine (10−4 M) and cytochalasin B (10−4 M) did not affect significantly Na+.K+‐. Mg2‐ and Ca2+ ‐ATPase activities. These results suggest that none of microtubules. microfilaments and contractile protein participates in the mechanism of [3H]5‐HT release from synaptosomes, in vitro.
THE NATURE OF THE TWO PROTEINS OF BRAIN SPECIFIC ANTIGEN 14‐3‐2
Authors: Bock Elisabeth , Fletcher Lynne , Rider C. C. , Taylor C. B. 
Published: October 2006

Abstract—The three isoenzymes of rat brain enolase (2‐phospho d‐glycerate hydrolase EC 4.2.1.11.) χχ, χγ and γγ were separated by ion‐exchange chromatography and were tested for reaction with an antiserum against brain specific antigen 14‐3‐2. This monospecific antiserum affects the enolase activity of only the χγ and γγ isoenzymes.Immunoelectrophoretic experiments show that the two proteins which react as 14‐3‐2 both contain γ enolase subunits, and one of these also contains χ enolase subunits.It is concluded that the 14‐3‐2 antigen and the γ enolase subunit are identical, and that the two proteins which react immunologically as 14‐3‐2 are the χγ and γγ enolase isoenzymes.
PYRIDOXAL‐5′‐PHOSPHATE AS A COFACTOR FOR RAT BRAIN HISTIDINE DECARBOXYLASE1
Authors: Palacios J. M. , Mengod G. , Grad, F. P)Catoste M. , Blanco I. 
Published: October 2006

Abstract—The cofactor requirements of brain histidine decarboxylase activity have been studied. Preincubation with carbonyl reagents caused inhibition of the activity ranging from 90% for 10−2m‐semicarbazide, 10−3m‐phenylhydrazide and 10−3m‐hydroxylamine to 50% for isonicotinic acid hydrazide. Sodium borohydride, a reducing agent, also caused complete inhibition of activity. The histidine decarboxylase activity was maximal at 10−4m‐pyridoxal‐P concentration and was inhibited at higher concentrations of the cofactor.The cofactor‐apoenzyme mode of binding was studied by dialysing brain homogenates against several media. Neither the dialysis against buffers alone nor against buffers containing semicarbazide nor cysteine plus EDTA caused a total loss of activity. A 50% of the activity dialysed easily while the other 50% remained ‘tightly’ bound to the apoenzyme. The dialysable and non dialysable activity is evenly distributed between the soluble and particulate activity.
β‐CARBOLINES: A TOOL FOR INVESTIGATING STRUCTURE‐ACTIVITY RELATIONSHIPS OF THE HIGH‐AFFINITY UPTAKE OF SEROTONIN, NORADRENALINE, DOPAMINE, GABA AND CHOLINE INTO A SYNAPTOSOME‐RICH FRACTION OF VARIOUS REGIONS FROM RAT BRAIN1
Authors: Rommelspacher H. , Strauss S. M. , Rehse K. 
Published: October 2006

Abstract— Tetrahydronorharmane (tryptoline), the condensation product of tryptamine and formaldehyde, inhibits the high‐affinity uptake of serotonin and to a smaller extent that of noradrenaline into a synaptosome‐rich fraction from the hippocampus and hypothalamus respectively of rats. The uptake mechanisms of dopaminergic neurones of the hypothalamus, cholinergic neurones of the hippocampus, and GABA‐ergic neurones of the cerebral cortex are affected to a much lesser degree. Substitution of tetrahydronorharmane by fluor‐, chlor‐, methyl‐, hydroxy‐, methoxy‐, and catechol‐groups alters the inhibition. Drugs with substituents which attract electrons are relatively good inhibitors of the uptake of serotonin. The indole‐ring contributes to the binding of the molecule probably by forming a charge transfer complex with the uptake molecule. Pyrido (3,4‐b)‐indoles (harmala alkaloids) are weak inhibitors of the serotonin‐uptake compared with respective piperidoindoles (tetrahydro‐β‐carbolines).The potency of the drugs to inhibit uptake is different for each uptake system. The order among the drugs with respect to their affinity for the uptake site varies, too.
γ‐GLUTAMYLHISTAMINE: A MAJOR PRODUCT OF HISTAMINE METABOLISM IN GANGLIA OF THE MARINE MOLLUSK, APLYSIA CALIFORNICA
Authors: Weinreich Daniel 
Published: October 2006

Abstract—The metabolism of histamine in the nervous system of Aplysia, was studied by incubating ganglia for various time periods in a medium containing radiolabelled histamine. After 4 h of incubation, >89% of the 3MH‐ or 14C‐label measured in the ganglion extract was converted to a single radioactive product whose electrophoretic and chromatographic mobilities were identical with γ‐glutamylhistamine. No evidence was found to indicate that radiolabelled histamine could be deaminated, N‐methylated, N‐acetylated, or oxidized in this nervous system. Acid hydrolysis of radioactive material prepared from ganglia incubated in either 14C‐histamine alone or in combination with 14C‐glutamate resulted in the liberation of labelled histamine and/or labelled glutamate. These results indicate that γ‐glutamyl‐ation of histamine may be an important physiological mechanism for histamine catabolism in molluscan nervous tissue.
EFFECT OF PHOSPHATIDYLSERINE ON ACETYLCHOLINE OUTPUT FROM THE CEREBRAL CORTEX OF THE RAT
Authors: Casamenti F. , Mantovani P. , Amaducci L. , Pepeu G. 
Published: October 2006

Abstract—The effect of sonicated suspensions of phosphatidylserine, phosphatidylethanolamine and phosphatidylcholine injected intravenously on acetylcholine release from the cerebral cortex was investigated in urethane anaesthetized rats. The electroeorticogram was also recorded.Phosphatidylserine caused a dose dependent, calcium dependent increase in acetylcholine output with no electrocorticografic changes. The increase, 75% peak effect after 150 mg/kg, was abolished by septal lesions and pretreatment with pimozide. Phosphatidylserine had no effect on acetylcholine release from brain slices in vitro.Phosphatidylethanolamine was approximately half as active as phosphatidylserine and phosphatidylcholine had no effect on acetylcholine output in vivo.It is concluded that phosphatidylserine exerts an indirect stimulating action on a septio‐cortical cholinergic pathway.
SUBCELLULAR LOCALIZATION OF PROTEIN CARBOXYL‐METHYLASE AND ITS SUBSTRATES IN RAT PITUITARY LOBES
Authors: Gagnon Claude , Axelrod Julius 
Published: October 2006

Abstract—Subcellular distribution of protein carboxyl‐methylase (PCM) and its endogenous substrates the methyl acceptor proteins (MAP) have been studied in the anterior, the posterior and the intermediate lobes of the rat pituitary gland. In all three lobes, PCM was found to be a cytosolic enzyme whereas the highest MAP specific capacity was observed in the lysate of the granular fractions. The methylated proteins from the lysates of the granular fractions and the cytosolic fractions were analyzed with a novel electrophoretic system which prevents the hydrolysis of the protein‐methyl esters. Gel electrophoretic profiles from the lysates of the granular fractions were different from those of the cytosolic fractions. In the lysatcs of the granular fractions. the MAP had a molecular weight of less than 25,000 suggesting that the methylated polypeptides in these fractions were the pituitary peptide hormones (and their subunits) and neurophysins.
LIPID‐MEDIATED GLYCOSYLATION OF A WHITE MATTER MEMBRANE GLYCOPROTEIN WITH AN APPARENT MOLECULAR WEIGHT OF 24,0001
Authors: B. Harford Joe , J. Waechter Charles 
Published: October 2006

AbstractWhite matter membrane preparations from pig brain catalyze the transfer of [14C]mannose from exogenous [14C]mannosylphosphoryldolichol into an endogenous oligosaccharide lipid. Under the same incubation conditions label is also incorporated into endogenous membrane glycoproteins. The enzymatic labeling of both classes of endogenous acceptors is stimulated by the addition of Ca2+. Several enzymatic properties of the mannosyltransferase activity responsible for the transfer of mannose from mannosylphosphoryldolichol into the oligosaccharide lipid intermediate have been examined. The [Man‐14C] oligosaccharide lipid synthesized by this in vitro system has the solubility, hydrolytic and chromatographic characteristics of a pyrophosphate‐linked oligosaccharide derivative of dolichol. The free [Man‐14C]oligosaccharide liberated from the carrier lipid by mild acid treatment is estimated to contain 8 glycose units. All of the [14C]mannosyl units in the [Man‐14C]oligosaccharide derived from exogenous [14C]mannosylphosphoryldolichol are released as free [14C]mannose by an α‐mannosi‐dase. No [14C]mannose is released during incubation with a β‐mannosidase. The presence of an N,N′‐diacetylchitobiose unit at the reducing end of the lipid‐bound [Man‐14C]oligosaccharide is indicated by its susceptibility to digestion by endo‐β‐N‐acetylglucosaminidase H.Pronase digestion of the enzymatically labeled [Man‐14C]glycoprotein yields a single [Man‐14C]gly‐copeptide fraction on Bio‐Gel P‐6 that appears to be slightly larger than the free [Man‐14C]oligosac‐charide released from the carrier lipid by mild acid hydrolysis. The [Man‐14C]glycopeptide is cleaved by endo‐β‐N‐acetylglucosaminidase H, and the neutral [Man‐14C]oligosaccharide product appears to be identical to the product formed when the lipid‐bound [Man‐14C]oligosaccharide is degraded by the endoglycosidase. The glycopeptide linkage in the [Man‐14C]glycoprotein is stable to mild alkali treatment. These results are consistent with the dolichol‐linked [Man‐14C]oligosaccharide, mannosy‐lated via exogenous [14C]mannosylphosphoryldoiichol, being subsequently transferred en bloc from dolichyl pyrophosphate to asparagine residues in endogenous membrane polypeptide acceptors. SDS‐polyacrylamide gel electrophoresis of the [Man‐14C]glycoprotein, labeled when white matter membranes are incubated with [14C]mannosylphosphoryldolichol. revealed a major labeled polypeptide with an apparent mol wt of 24,000. A minor labeled membrane glycoprotein is also seen, having an apparent mol wt of 105,000.
DIVALENT CATION SPECIFICITY OF THE CALCIUM REQUIREMENT FOR FAST TRANSPORT OF PROTEINS IN AXONS OF DESHEATHED NERVES
Authors: Lavoie P.‐A. , Bolen F. , Hammerschlag R. 
Published: October 2006

AbstractThe presence of a requirement for calcium during the fast transport of [3H]protein in axons was assessed in desheathed spinal nerves of bullfrog. The nerves were desheathed locally along 4 mm of their length, and desheathing was judged effective on the basis of an enhanced uptake of [3H]leucine into that region of nerve trunk. Desheathing per se had a slight inhibitory effect on transport. Incubation of desheathed nerve trunks in calcium‐free medium reduced transport by 60‐80% relative to that in desheathed nerves incubated in normal medium. Addition of Mg2+ or Sr2+ to the calcium‐free medium allowed transport to proceed normally. Addition of Co2+ or Mn2+ to normal medium did not affect transport in desheathed isolated nerve trunks. When ganglia and nerve trunks were both incubated in medium containing 0.18 mM‐CoCl2, transport was depressed to a similar extent proximal and distal to the desheathed region. This again indicates that Co2+ does not inhibit transport in desheathed nerves, whereas it does inhibit transport in the ganglia. Additive inhibitory effects were observed when ganglia were incubated in medium containing 0.018 mM‐CoCl2, and desheathed nerves were incubated in calcium‐free medium. Differences in the divalent cation specificities of the axonal and ganglionic calcium requirements suggest that calcium supports transport in nerves in a manner distinct from its role in maintaining transport in spinal ganglia. It is concluded that the ganglionic calcium requirement involves initiation of axonal transport in the soma rather than translocation in the intraganglionic region of axon.
[3H]HARMALINE AS A SPECIFIC LIGAND OF MAO A–II. MEASUREMENT OF THE TURNOVER RATES OF MAO A DURING ONTOGENESIS IN THE RAT BRAIN
Authors: Nelson D. L. , Herbet A. , Glowinski J. , Hamon M. 
Published: October 2006

AbstractThe combined measurement of MAO A activity (using [3H]5‐HT as a specific substrate) and [3H]harmaline binding capacity indicated that the concentration of MAO A in brain was higher in 14‐28 day old rats than in adult animals. The turnover rates of this enzyme in the forebrain and the brain stem of young (14‐28 day old) and adult rats were calculated by following the recovery of MAO A activity and of [3H]harmaline binding capacity after an acute treatment with pargyline (75mg/kg i.p.). Both the fractional rate constant for MAO A degradation and its synthesis rate per g of fresh tissue were significantly higher in young animals. However, the calculation of the absolute synthesis rates of MAO A per brain area gave very similar values in young and adult animals: 1.3‐1.5 × 1013 molecules of MAO A synthesized per day in the forebrain and 2.3‐2.9 × 1012 molecules per day in the brain stern.The results illustrate the validity of using [3H]harmaline binding to evaluate possible changes in the turnover rate of MAO A in tissues.
RELEASE OF [3H]GABA FROM IN VITRO PREPARATIONS: COMPARISON OF THE EFFECT OF DABA AND β‐ALANINE ON THE K+ AND PROTOVERATRINE STIMULATED RELEASE OF [3H]GABA FROM BRAIN SLICES AND SYNAPTOSOMES1
Authors: Hammerstad J. P. , Cawthon M. L. , Lytle C. R. 
Published: October 2006

AbstractIt has been proposed that the major portion of [3H]GABA released from rat cortical slices upon exposure to high K+ comes from a neuronal pool. Using carrier mediated exchange diffusion of DABA or β‐alanine in the superfusion medium for GABA in the slice as a technique for manipulating neuronal and glial pools of GABA, it was found that DABA but not β‐alanine substantially reduced the K+ stimulated release of [3H]GABA. The present study using synaptosomes as an in vitro model of the nerve ending was undertaken to ascertain whether this neuronal pool of releasable [3H]GABA was associated with a specific transmitter pool in nerve endings. A continuous superfusion system employing a Ca2+ pulse to produce a calcium coupled release (Levyet al, 1973) was used to study the effect of two concentrations (20 μm, 1 mm) of DABA and β‐alanine on the release of [3H]GABA from synaptosomes. In contrast to the results in slices, DABA at both concentrations had no effect on the release of [3H]GABA from synaptosomes in spite of evidence that exchange diffusion was occurring. With protoveratrine as the releasing agent there was no effect of DABA on the release of [3H]GABA from either slices or synaptosomes. The results suggest that the major portion of [3H]GABA released from cortical slices by high K+ comes from a non‐transmitter pool in the neuron. Use of K+ stimulated release of amino acids from cortical slices as a criterion for neurotransmitter function must be viewed with caution.
NEUROCHEMICAL PARAMETERS IN THE HYPERRESPONSIVE PHASE AFTER A SINGLE DOSE OF NEUROLEPTICS TO MICE
Authors: Hyttel John 
Published: October 2006

Abstract— Four days after a single dose of teflutixol (5 mg/kg i.p.), at which time mice are superresponsive to dopamine agonists, e.g. apomorphine, the specific binding of [3H]haloperidol, [3H]cis (Z)‐flupenthixol, [3H]apomorphine, [3H]dopamine, [3H]propylbenzilylcholine mustard and [3H]GABA to striatal membranes in vitro is equal to that of saline‐treated mice. Specific binding of [3H]haloperidol is also unchanged 3 days following a single dose of fluphenazine (5mg/kg i.p.) and 2 days following haloperidol (5 mg/kg i.p.), but slightly decreased 3 days following cis(Z)‐flupenthixol (5 mg/kg i.p.).The possibility that remaining neuroleptic or active metabolites could obscure a slight increase in dopamine receptor binding was rejected, since remaining amounts of [3H]teflutixol in the final binding assay 4 days after intraperitoneal injection of [3H]teflutixol (5 mg/kg) were too small to influence the binding of [3H]haloperidol in vitro.It is concluded that the pharmacological superresponsiveness and the decrease in dopamine synthesis and release seen after the initial receptor blockade following a single dose of neuroleptic drugs in mice are nor accompanied by changes in dopamine, muscarine or GABAergic receptor characteristics in corpus striatum. The possibility that changes occur in a small number of functional operative dopamine receptors cannot be excluded, however.
DEVELOPMENT OF ACETYLCHOLINESTERASE MULTIPLE MOLECULAR FORMS IN CHICKEN MUSCLES
Authors: Bajgar J. , Pařízek J. , Procházková O. 
Published: October 2006

Abstract— AChE activity and protein content in chicken ALD and PLD muscles was studied during pre‐ and postnatal development. Protein content in both muscles increased whereas AChE activity increased in ALD and decreased in PLD during development. All studied values reached the steady‐state 3 weeks after hatching.Electrophoretic separation of the samples showed three molecular forms of AChE present in both adult ALD and PLD muscles. Two molecular forms in ALD muscle increased slowly, one form quickly. On the other hand, the activity of AChE forms in PLD muscle decreased with different rates. It appears from these results that the multiple molecular forms of AChE in muscles are not of the same physiological importance.
DECREASED AXONAL FLUX OF RETROGRADELY TRANSPORTED GLYCOPROTEINS IN EARLY EXPERIMENTAL DIABETES
Authors: Jakobsen J. , Sidenius P. 
Published: October 2006

Abstract— Anterograde and retrograde flux of axonal transported glycoproteins were examined in streptozotocin diabetic rats with 4 weeks’duration of the metabolic derangement.[3H]Fucose and [14C]NeuNAc were injected into the fifth lumbar root ganglion and the accumulation of TCA‐PTA insoluble activity proximal and distal to a sciatic nerve ligature was measured.Accumulation of glycoproteins during 2 h collection periods was decreased distal to a ligature in diabetic animals whereas no abnormality of proximal accumulation was observed. These findings demonstrate an abnormality of the retrograde transport of glycoproteins in early experimental diabetes.
CHARACTERIZATION OF THE BASIS FOR DIFFERENCES IN SERUM DBH ACTIVITY IN IMMATURE AND ADULT RATS BY USE OF HOMOLOGOUS ANTIBODY
Authors: Grzanna R. , Nelson M. F. , Weinshilboum R. M. , Dunnette J. , Coyle J. T. 
Published: October 2006

Abstract– Rat serum dopamine‐β‐hydroxylase (DBH) activity decreased 5‐7‐fold between 15 and 60 days of age. Immunoprecipitation performed with homologous antibody (guinea‐pig anti‐rat adrenal DBH) showed that during this time period the quantity of antibody necessary to precipitate 50% of the enzymatic activity (AD50) decreased 5‐fold from 0.25 to 0.05 μl/ml. The biochemical properties of rat serum DBH at 15 and 60 days of age were compared to test the hypothesis that there might be different biochemical forms of the enzyme in the blood of immature and adult rats. Thermal stability, apparent Km for tyramine, electrophoretic mobility, pH optima and elution profile on gel filtratioh chromatography were all found to be similar for rat serum DBH at both ages. On the basis of homospecific activity and multiple similarities in biochemical characteristics, it appears that differences in serum activity at the two ages reflect differences in the steady‐state levels of enzyme.To determine the turnover of serum DBH in the two age groups, the recovery of enzyme activity was monitored after acute clearance of the circulating pool of DBH by treatment with the homologous antiserum. Immunotitration of DBH activity in vivo indicated that the total pool of serum enzyme was 4‐fold greater in the mature rat than in 4‐day‐olds. After treatment of adult rats with 2μl of homologous antiserum, serum DBH activity was reduced by 85% with a half‐life of recovery of 3.0 ± 0.6 days; the estimated fractional rate of degradation was 0.23 ± 0.06 day−1 and the rate of entrance was 2.3 ± 0.2 units/ml/day. After treatment of 4‐day‐old rats with 1 μl of homologous antiserum, serum DBH activity was reduced by 95% with a half‐life of recovery of 3.3 ± 0.5 days: the estimated average fractional rate of degradation was 0.22 ± 0.06 day−1 and the average rate of entrance was 10.7 ± 1.6 units/ml/day. Thus, the several‐fold difference in steady‐state levels of serum DBH in rat pups as compared to adult rats appears to be due to greatly increased rates of entrance of the enzyme in the immature rats.