bluuebunny/crossref_metadata_2025_split huggingface dataset:
MODULATION OF THE TURNOVER RATE OF ACETYLCHOLINE IN RAT BRAIN BY INTRAVENTRICULAR INJECTIONS OF THYROTROPIN‐RELEASING HORMONE, SOMATOSTATIN, NEUROTENSIN AND ANGIOTENSIN II
Authors: Malthe‐Sorenssen D. , Wood P. L. , Cheney D. L. , Costa E. 
Published: October 2006

Abstract—The turnover rate of acetylcholine (TRACh) was measured in frontal and parietal cortex striatum, hippocampus, diencephalon and brain stem following the intraventricular injection of thyrotropin‐releasing hormone (TRH), somatostatin, neurotensin and angiotensin II. These peptides selectively change the TRACh of various brain regions suggesting specific and independent actions. This specificity of action was also tested by injecting L‐prolylglycine, poly‐L‐proline and poly‐L‐glutamate. None of these synthetic peptides affect the TRACh. TRH increases the TRACh in parietal but not in frontal cortex whereas somatostatin, neurotensin and angiotensin II failed to change the TRACh in these cortical areas. Somatostatin and neurotensin increase the TRACh in diencephalon, whereas TRH and angiotensin II do not. All four peptides decrease the acetylcholine (ACh) content of parietal cortex but not that of frontal cortex. Only somatostatin changes the TRACh in pons medulla. Larger doses of TRH, neurotensin and angiotensin II fail to elicit greater or more general changes in TRACh. In contrast, high doses of somatostatin increase the TRACh of hippocampus and induce‘barrel’rotation. Intraseptal injections of somatostatin induce a long lasting catalepsy but fail to change hippocampal TRACh or to elicit‘barrel’rotation
ADRENERGIC ENZYMES IN CULTURED MOUSE NEUROBLASTOMA: ABSENCE OF DETECTABLE AROMATIC‐l‐AMINO‐ACID DECARBOXYLASE1
Authors: Waymire Jack C. , Gilmer‐Waymire Katrina 
Published: October 2006

Abstract—The relative activities of tyrosine hydroxylase, aromatic‐l‐amino‐acid decarboxylase and dopamine beta‐hydroxylase were established in a number of clones of neuroblastoma cells isolated from the uncloned mouse C‐1300 tumor. One clone, NBD‐2, was chosen for further analysis on the basis of its relatively high activities of tyrosine hydroxylase and dopamine beta‐hydroxylase. The levels of these enzymes, and monoamine oxidase and catechol O‐methyltransferase, were at least 20‐80 fold lower in the neuroblastoma culture than in mouse superior cervical ganglion. More importantly, aromatic‐l‐amino‐acid decarboxylase activity was not even detectable in any neuroblastoma clone examined. Based on the relative sensitivities of the tyrosine hydroxylase and aromatic‐l‐amino‐acid decarboxylase assays and on the ratio of these two enzymes in the mouse ganglion, decarboxylase activity is more than 10 fold lower in the cultured cells than would be predicted on the basis of tyrosine hydroxylase activity.Dialysis and mixing studies with neuroblastoma extracts and partially purified aromatic‐l‐amino‐acid decarboxylase did not reveal the presence of any endogenous inhibitors that could account for the low level of decarboxylase activity in the cultured cells.During growth of the neuroblastoma cells to confluency, only one enzyme, monoamine oxidase, exhibited an elevated specific activity on the basis of cell number. However, when based on the amount of protein, the specific activity of all measurable enzymes increased in culture‐because cell protein decreased 5 fold during growth to confluency. These findings are discussed with respect to individual cell function.
BINDING OF 5‐HYDROXYTRYPTAMINE TO ACIDIC LIPIDS IN AN AQUEOUS MEDIUM
Authors: Johnson David A. , Merlone Steven C. , Loh Horace H. , Ellman George L. 
Published: October 2006

Abstract—The affinities of 5‐hydroxy‐[3H]tryptamine (5‐HT) for cerebroside sulfate, 1‐phosphatidylinositol, 1‐phosphatidylinositol 4‐phosphate, 1‐phosphatidylinositol 4,5‐bisphosphate, phosphatidic acid, and phosphatidyl serine were determined in an aqueous medium. They were observed to be, in general, much lower than and poorly correlated with the values previously reported by Johnsonet al (1977a), measured in isobutanol. This suggested that these lipids probably are not 5‐HT receptors and that drug affinities measured in organic media must be evaluated with caution.
PHOSPHOLTPID METABOLISM IN ISOLATED NEURONAL AND GLIAL CELLS FROM BRAINS OF 17‐DAY OLD RATS1
Authors: Marggraf W. D. , Wang H. , Kanfer J. N. 
Published: October 2006

Abstract—Neuronal and glial cells were isolated from the brains of 17‐day old rats and incubated for 5 h with either radioactive inorganic phosphate, palmitate, serine, choline or ethanolamine in a tissue culture medium. A comparison of the results suggests that both neuronal and glial cells exhibit effective de novo, phospholipid synthesis and that the observed differences in the uptake are due more to quantitative rather than qualitative differences in phospholipid metabolism of both cell types. Incubations of the combined neuronal and glial fractions with 32PO4 and [3H]palmitate result in incorporations up to 100% higher than calculated from incubations of the separate fractions, suggesting that phospholipid metabolism of neuronal and glial cells may exhibit cooperativity.
CHARACTERISTICS OF GLUTAMINE vs GLUTAMATE TRANSPORT IN ISOLATED GLIA AND SYNAPTOSOMES
Authors: Weiler C. T. , Nyström B. , Hamberger A. 
Published: October 2006

Abstract—The uptake of the neurotransmitter candidates glutamate and aspartate into synaptosomes and bulk‐isolated glia was considerably more rapid than the uptake of the suspected transmitter‐precursor glutamine at low concentrations (10 μM). Glial uptake in all cases was one‐fifth to one‐third of synaptosomal, whereas isolated neurons attained very low tissue: medium ratios, probably reflecting damage to the neurons sustained during isolation. The glial and synaptosomal uptakes of glutamate both obeyed dual high‐ and low‐affinity kinetics and were negligible in the absence of external sodium, whereas glutamine was taken up in either case by an exclusively low‐affinity transport system exhibiting no sodium‐dependence. Glutamine was considerably metabolized to glutamate following transport by both glia and synaptosomes whereas glutamate remained unmetabolized
γ‐VINYL GABA: EFFECTS OF CHRONIC ADMINISTRATION ON THE METABOLISM OF GABA AND OTHER AMINO COMPOUNDS IN RAT BRAIN
Authors: Perry Thomas L. , Kish Stephen J. , Hansen Shirley 
Published: October 2006

AbstractRats were given γ‐vinyl GABA (4‐amino‐hex‐5‐enoic acid), a new irreversible inhibitor of GABA aminotransferase (GABA‐T), by daily subcutaneous injection (100mgkg) for 11 days. Amino acids were quantitated in the brains of the γ‐vinyl GABA‐treated and control animals 24 h after the last injection, and enzyme activities of GABA‐T and glutamic acid decarboxylase (GAD) were measured. Chronic administration of γ‐vinyl GABA produced a 150% increase in brain GABA content, along with marked increases in the contents of B‐alanine and homocarnosine. Brain GABA‐T activity was reduced by 26%, and GAD activity was reduced by 22%. In addition, γ‐vinyl GABA caused a marked increase in hypotaurine content in rat brain, suggesting that it acts as an inhibitor of hypotaurine dehydrogenase, and it produced significant decreases in brain contents of glutamine and threonine. Although it is an effective GABA‐T inhibitor, γ‐vinyl GABA apparently affects several other brain enzymes as well, and it may not be an ideal drug for elevating brain GABA levels in man.
CHARACTERIZATION AND TOPOGRAPHY OF THE GLYCOPROTEINS OF ADRENAL CHROMAFFIN GRANULES
Authors: Huber E. , Köunig P. , Schuler G. , Aberer W. , Plattner H. , Winkler H. 
Published: October 2006

AbstractThe glycoproteins of the membranes of bovine chromaffin granules were characterized by two polyacrylamide gel electrophoresis systems. Five components (I‐V) were demonstrated with apparent molecular weights ranging in the unreduced form from 45,000 to 150,000. Glycoprotein I was identified as the enzyme dopamine β‐hydroxylase. Four of these glycoproteins (with the exception of component IV) were apparently also present in the membranes of pig and horse chromaffin granules. The soluble proteins of chromaffin granules contained at least three glycoproteins. Only glycoprotein I (dopamine β‐hydroxylase) was present both in the soluble content and in the membranes of chromaffin granules. Affinity chromatography with lectins demonstrated that from the soluble proteins only dopamine β‐hydroxylase was adsorbed by concanavalin A, whereas none of these proteins reacted with wheat germ lectin and Ricinus communis agglutinin. Three membrane proteins including dopamine β‐hydroxylase and glycoprotein II as major components were adsorbed by concanavalin A, whereas wheat germ lectin bound only component II and a small amount of component III. By electron microscopy it was demonstrated that concanavalin A did not bind to intact chromaffin granules whereas ruthenium red and cationized ferritin did. Isotope labelling after galactose oxidase treatment revealed that at least the carbohydrate portion of the major glycoproteins is present on the inner side of the granule membranes facing the content.
EVIDENCE FOR THE BIOSYNTHESIS OF MANNOSYLPHOSPHORYLDOLICHOL AND N‐ACETYLGLUCOSAMINYLPYROPHOSPHORYLDOLICHOL BY AN AXOLEMMA‐ENRICHED MEMBRANE PREPARATION FROM BOVINE WHITE MATTER
Authors: HarforD J. B. , Waechter C. J. , Saul R. , DeVries G. H. 
Published: October 2006

AbstractAn axolemma‐enriched membrane fraction prepared by an improved procedure from bovine white matter catalyzes the enzymatic transfer of [14C]mannose and N‐acetyl[14C]glucosamine from their nucleotide derivatives into a mannolipid and an N‐acetylglucosaminyl lipid in the presence of exogenous dolichyl monophosphate. The labeled glycolipid products have the chemical and chromatographic characteristics of mannosylphosphoryldolichol and N‐acetylglucosaminylpyrophosphoryldolichol. The initial rates of synthesis of the glycolipids by the axolemma‐enriched membrane fraction have been compared with the initial rates of glycolipid formation catalyzed by a microsomal preparation and myelin in the presence or absence of dolichyl monophosphate. Essentially no glycolipid synthesis was observed when either GDP‐[14C]mannose or UDP‐N‐acetyl[14C]glucosamine were incubated with myelin in the presence or absence of exogenous dolichyl monophosphate. A comparison of the initial rates of synthesis of the glycolipids using endogenous acceptor lipid revealed that the rate of formation of mannolipid was 7 times faster for the microsomal membranes than the axolemma‐enriched membranes. In the presence of an amount of dolichyl monophosphate approaching saturation the initial rate of glycolipid synthesis was markedly enhanced for both membrane preparations. However, due to a more dramatic enhancement in the axolemma‐enriched membranes the initial rate of mannolipid synthesis was only approx. 2.5 times greater in the microsomal membranes. A similar observation was made when the initial rates of N‐acetylglucosaminyl lipid synthesis were compared for axolemma‐enriched and microsomal preparations in the presence and absence of exogenous dolichyl monophosphate. These studies indicate that the axolemma‐enriched membranes have a relatively lower content of dolichyl monophosphate than the microsomal membranes although the difference in the amount of mannosyltransferase is only two to three‐fold lower.The presence of a sugar nucleotide pyrophosphatase activity capable of degrading GDP‐mannose and UDP‐N‐acetylglucosamine has also been demonstrated in the axolemma‐enriched membrane fraction.
THE EFFECT OF TRIETHYLLEAD ON TOTAL AND MYELIN PROTEIN SYNTHESIS IN RAT FOREBRAIN SLICES
Authors: Konat G. , Offner H. , Clausen J. 
Published: October 2006

AbstractRats (20‐day‐old) were acutely intoxicated with triethyllead and their forebrains were studied during the following 14 days. All the lead in the tissue was found in the form of triethyllead, proving that the toxin per se was responsible for the pathological changes observed in the organ. The incorporation of [14C]leucine into the acid‐insoluble protein was suppressed in the forebrain slices prepared from the intoxicated animals as well as in the slices, to which PbEt3 was added in vitro. In both systems the synthesis of myelin protein was inhibited more than the total protein synthesis. The results suggest a specificity of triethyllead toward processes involved in the furnishing of the myelin membrane proteins.
EFFECT OF SENSORY STIMULATION ON AMINO ACID INCORPORATION INTO BRAIN PROTEINS IN VIVO
Authors: Abdul‐Ghani A.‐S. , Luqmani Y. A. , Bradford H. F. 
Published: October 2006

Abstract— Stimulation (AES) of the brachial plexus of anaesthetised rats resulted in an increased incorporation of carbon from [U‐14C]glucose into TCA‐insoluble proteins in the contralateral cerebral hemisphere, as compared with the ipsi‐lateral hemisphere. The greatest change was observed in the sensori‐motor cortex grey matter.Following intraventricular injections of [U‐14C]glucose, the changes caused by brachial plexus stimulation were variable, depending on which hemisphere received the label. The injection itself severely inhibited the incorporation into protein. Neither the injection, nor stimulation affected the conversion of [U‐14C]glucose into amino acids or its relative distribution between the two hemispheres.
CHARACTERIZATION AND SUBCELLULAR LOCALIZATION OF BRAIN MUSCARINIC RECEPTORS LABELLED IN VIVO BY [3H]DEXETIMIDE
Authors: Laduron P. M. , Janssen P. F. M. 
Published: October 2006

Abstract— [3H]Dexetimide specifically labels brain muscarinic receptors in vivo. After i.v. injection of labelled drug into rats, radioactivity specifically accumulates in brain regions containing muscarinic receptors but not in cerebellum. This accumulation is stereospecific, saturable and displaceable by unhbelled dexetimide. In contrast, [3H]levetimide, the inactive enantiomer, does not show such preferential uptake or stereospecific displacement.An analytical approach was used to study the subcellular distribution of [3H]dexetimide binding sites. After differential centrifugation the binding sites are mainly recovered in the microsomal fraction from different brain regions but not from the cerebellum. After displacement the radioactivity is found in the supernatant. After equilibration in a density gradient the distribution pattern of [3H]dexetimide is bimodal, like that of 5′‐nucleotidase, with a major peak in a region of low density.When the microsomal fraction was treated with digitcnin, three groups of membrane were characterized by isopycnic centrifugation on the basis of their differential shift to higher densities. Evidence is provided that the postsynaptic membranes bearing muscarinic receptors belong to the class of plasma membranes. Finally, digitonin treatment may represent a useful tool to produce subfractions enriched in postsynaptic membranes which can now be identified biochemically in binding experiments.
SOME CHARACTERISTICS OF ATPase ACTIVITY IN A BRAIN MICROTUBULE PROTEIN PREPARATION
Authors: Larsson Harkan , Wallin Margareta , Edström Anders 
Published: October 2006

Abstract— The Mg‐ and Ca‐ATPase activities in a brain tubulin preparation have been measured. The activity of the microtubule protein (MTP) preparation was optimal, 3‐4.5 nmol Pi/mg protein/min, at pH 8.0 in the presence of 1‐2 mm‐Mg2+ or Ca2+, with a half maximal stimulation at about 0.3 mm concentration of either of the divalent ions.Phosphocellulose (PC) purified tubulin exhibited no or very low activity (0‐2 nmol Pi/mg protein/min).The majority of ATPase activity was found in the microtubule associated proteins (MAP) fraction. It was stimulated by Mg2+ and Ca2+, inhibited by NaF or high ionic strength but unaffected by vanadate at 10−4m. In decreasing order of effectiveness ATP, GTP, UTP, CTP and ADP were hydrolyzed. p‐Npp was a poor substrate. Vmax values for Mg‐ and Ca‐ATPase activities were about 15 and 10 nmol Pi/mg protein/min, respectively with a Km value of about 25 μm. However, double reciprocal plots disclosed more complicated kinetics, which were not fully resolved.The activity was largely confined to 30‐36S material (i.e.‘rings’and 'spirals'). The protein responsible for the ATPase activity is possibly the smaller one of the two (or three) high molecular weight (HMW) proteins of mol wt over 200,000.There are similarities between this enzyme and both flagellar dynein and myosin. However, the present ATPase differs from myosin in several important aspects (i.e. ionic requirements). Furthermore, no peptides of the myosin type were found upon electrophoretic analysis of the MAP fraction.
FORMATION OF A SUPPLEMENTAL LONG TIME‐CONSTANT RESERVOIR OF HIGH ENERGY PHOSPHATE BY BRAIN IN VIVO AND IN VITRO AND ITS REVERSIBLE DEPLETION BY POTASSIUM DEPOLARIZATION
Authors: Woznicki Dennis T. , Walker James B. 
Published: October 2006

Abstract—Brains of mice fed a diet containing 1% cyclocreatine (1‐carboxymethyl‐2‐iminoimidazolidine) accumulated the high energy phosphate compound cyclocreatine‐P (1‐carboxymethyl‐2‐imino‐3‐phosphonoimidazolidine), an analogue of creatine‐P (phosphocreatine). During a 50‐day feeding period mouse brain cyclocreatine‐P increased linearly to 14 μmol/g fresh wt; during this time the total phosphagen level of brain, creatine‐P plus cyclocreatine‐P, increased from 3 to 15 μmol/g. When the blood‐brain barrier was circumvented, a more rapid accumulation of synthetic phosphagen was achieved. Minced brain preparations from 11 to 15‐day chick embryos incubated in vitro with 30 mm‐cyclocreatine accumulated 10 μmol/g of cyclocreatine‐P in 90 min, and this novel high energy phosphate pool could be depleted by incubation with 105 mm‐potassium ions or 3 μm‐valinomycin. Subsequent regeneration of the depleted pools could also be demonstrated. Brain tissue containing a supplemental reservoir of cyclocreatine‐P, which is utilized to regenerate ATP much more slowly than creatine‐P, might be better able to withstand anoxia and certain other metabolic stresses, but this has not been established. However, the marked delay of onset of rigor previously shown to occur in ischemic heart and skeletal muscle of cyclocreatine‐fed animals is compatible with this suggestion.
BIOSYNTHESIS OF HETEROGENEOUS FORMS OF MAMMALIAN BRAIN TUBULIN SUBUNITS BY MULTIPLE MESSENGER RNAs
Authors: Marotta Charles A. , Strocchi Paola , Gilbert Jeffrey M. 
Published: October 2006

Abstract—Heterogeneity among the primary translation products of rat brain tubulin messenger RNA was examined. On two‐dimensional gels native cytoplasmic tubulin from randomly bred rats (PB21) consists of two groups of α tubulin subunits among which the most acidic forms, α1 and α2, are most abundant; and β tubulin consists of a minimum of two species, β1 and β2. In the same group of animals the primary translation products of rat brain tubulin mRNA consist of at least these four subunit forms (α1α2, β1 and β2); however, minor basic forms of α subunits were not synthesized. This same result was obtained from a homologous brain protein synthesizing system, a heterologous system prepared from brain polysomes and rabbit reticulocyte initiation factors, and a wheat germ lysate programmed with brain poly A mRNA. A variant form of brain tubulin was found in rats bred monogamously for over 30 generations (MB71 rats). MB71 brain polysomes synthesize overlapping a subunits which migrate in two‐dimensional gels to the α1 position, and the typical PB21 α2 is not present. The addition of PB21 brain mRNA to a protein synthesizing system composed of MB71 polysomes plus reticulocyte initiation factors allowed synthesis of the typical α2 tubulin in addition to the MB71 tubulin subunits. The structural relationship among subunits was examined by radioiodinated peptide mapping. The α subunits are structurally different from the β subunits; however, among the major tyrosine‐containing tryptic peptides no prominent differences were observed between α1 and α2, or between β1 and β2 by the radioiodination procedure. The results provide evidence for heterogeneity among the primary translation products of brain tubulin mRNA, and for the existence of multiple functional tubulin genes in rat brain.
NIACIN AND NIACINAMIDE ACCUMULATION BY RABBIT BRAIN SLICES AND CHOROID PLEXUS IN VITRO
Authors: SPECTQR REYNOLD , KELLEY PAUL 
Published: October 2006

AbstractThe transport into and release of14C‐labeled niacin and niacinamide from rabbit brain slices and isolated choroid plexuses were studied. In vitro, both brain slices and choroid plexus concentrated 14C by specific, energy‐dependent mechanisms when [14C]niacinamide was added to the incubation medium. The saturable accumulation velocities, which were linear for 30 min, depended, in part, on incorporation of the [14C]niacinamide into NAD. The XT and Ymax for 14C accumulation with [14C]niacinamide in the medium by brain slices and choroid plexus were 0.80 μM and 1.45 μmolkg−1 (30 min)−1, and 0.23 μM and 18.6 μmol kg−1 (30 min)−1 respectively. In vitro, the choroid plexus, unlike brain slices, vigorously concentrated 14C by a separate, specific energy‐dependent process when 14C niacin was added to the incubation medium. The saturable accumulation velocity, which was linear for 30 min, depended completely on the metabolism of [14C]niacin. The KT and Ymax for14C accumulation by choroid plexus with [14C]niacin in the medium were 18.1 μM and 439 μmol kg−1 (30 min)−1 respectively. Whether preincubated in [14C]niacin or [14C]niacinamide, choroid plexus released predominantly [14C]niacinamide.
Experimental Scrapie in the Mouse: Electrophoretic and Sedimentation Properties of the Partially Purified Agent
Authors: Prusiner Stanley B. , Garfin David E. , Cochran S. Patricia , McKinley Michael P. , Groth Darlene F. , Hadlow William J. , Race Richard E. , Eklund Carl M. 
Published: October 2006

Abstract: Some biochemical and biophysical properties of the scrapie agent in a partially purified fraction P5 from murine spleen are described in this communication. The agent was stable in the nonionic detergents Triton X‐100 and Nonidet P40 and stable in the nondenaturing, anionic detergents sodium cholate and sodium N‐lauroyl sarcosinate. In contrast, sodium dodecyl sulfate (SDS) inactivated the agent at high concentrations (1% or >) when the detergent‐to‐protein ratio approached 1.5 g SDS/g protein. The agent was resistant to inactivation by nucleases and proteases, even in the presence of 0.1% SDS. A broad peak of infectivity was exhibited in modified colloidal silica (Percoll) density gradients. Maximal titers were found at a Percoll density of 1.10 g/cm3 in the presence and absence of 0.05% SDS. Gel electrophoresis of the agent in the presence of 0.1% SDS resulted in inactivation of >95% of the agent loaded onto the gel. Free‐flow electrophoresis showed that >99% of the agent in fraction P5 migrated toward the anode, but not as a discrete species. Sedimentation analysis of the agent in fraction P5 in the presence of 1% lysolecithin showed that the agent has a sedimentation coefficient of <300S but >30S. Heating P5 preparations caused the agent to associate with cellular elements and form aggregates with sedimentation coefficients >10,000S. Removal by differential centrifugation of the large forms of the agent produced upon heating permitted characterization of a discrete subpopulation of scrapie agent particles. Rate‐zonal sucrose gradient studies showed that >>95% of the infectivity in this subpopulation sedimented as uniform particles with a sedimentation coefficient of 240S.