bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE DIRECT MEASUREMENT OF THE AXOPLASMIC TRANSPORT OF INDIVIDUAL RNA SPECIES: TRANSFER BUT NOT RIBOSOMAL RNA IS TRANSPORTED
Authors: Gunning P. W. , Por S. B. , Langford C. J. , Scheffer J. , Austin L. , Jeffrey P. L. 
Published: October 2006

AbstractAnalysis of chick retinal and tectal RNA revealed that in addition to the major cytoplasmic RNAs (rRNA and tRNA), a number of the small mol wt nuclear RNAs (snRNAs) can also be detected. Subfractionation data indicated that one of these molecules, DD′, is of at least 95% nuclear location within the retina. Thus, very little, if any, of the retinal DD′ is available for axoplasmic transport from the retina into the optic nerve and tectum.Following intraocular injection of [3H]uridine, considerable incorporation of isotope into DD′ was observed within the optic tectum after 4, 8 and 16 days. This result indicates the presence of considerable local (i.e. tectal) synthesis. The specific activities of 29S, 18S and 5S rRNA and 4s tRNA relative to that of DD′ were measured in the optic tectum 8 and 16 days after the intraocular introduction of [3H]uridine. The same measurements were also made in intracranially injected animals. While the 29S/DD′, 18S/DD′ and 5S/DD′ specific activity ratios obtained were independent of the injection route, the 4S/DD′ ratio obtained from intraocularly injected animals was significantly greater (at least 2‐fold) than that obtained from intracranially injected animals. Similar analysis was also performed with the optic nerve complex at 16 days post‐injection with identical results.These results demonstrate that tRNA, but not rRNA, is transported from the retina into the optic nerve and tectum in the 2‐day‐old chicken.
CHARACTERIZATION OF THE Ca2+‐INDUCED PROTEOLYTIC ACTIVATION OF TRYPTOPHAN HYDROXYLASE FROM THE RAT BRAIN STEM
Authors: Hamon Michel , Bourgoin Sylvie 
Published: October 2006

AbstractThe incubation of the 35,000 g supernatant of a rat brain stem homogenate in the presence of 7.5 mM‐CaC12 for 10 min at 25°C resulted in a more than 2‐fold increase in its tryptophan hydroxylase activity. This activation was irreversible and involved a reduction in the molecular weight of the enzyme, from 220,000 to 160,000. The partially proteolysed tryptophan hydroxylase, in contrast to the native enzyme, could not be activated by trypsin, sodium dodecyl sulphate, phosphatidylserine or phosphorylating conditions; dithiothreitol and Fe2+ were the only compounds whose stimulating effect on the enzymatic activity was not prevented by the Ca2+ ‐induced proteolysis of tryptophan hydroxylase.These findings suggest that the mol. wt. 60,000 fragment removed by the Ca2+ dependent neutral proteinase plays a critical role in the regulatory properties of tryptophan hydroxylase.
A COMPARATIVE STUDY OF PINEAL ACETYL‐CoA HYDROLASE AND N‐ACETYLTRANSFERASE ACTIVITIES
Authors: Namboodiri M. A. A. , Namboodiri Mini A. , Weller Joan L. , Klein D. C. 
Published: October 2006

Abstractpineal acetyl‐CoA hydrolase is measurable at 4 days before birth. It increases rapidly to a maximum of 0.37 nmol/min/0.1 mg protein during the first week after birth, thereafter gradually decreasing and stabilizing at adult levels (0.27 nmol/min/0.1 mg protein) 3‐4 weeks after birth. Unlike A/‐acetyltransferase, the activity of acetyl‐CoA hydrolase does not increase following treatment with isoproterenol, does not exhibit a circadian rhythm and is not inactivated on exposure of the animals to light at night. In addition, denervation of the pineal gland does not alter acetyl‐CoA hydrolase activity.
PROTEIN PROFILES OF RAT EMBRYO CEREBRAL CELLS DURING DIFFERENTIATION IN CULTURE
Authors: Richter‐Landsberg C. , Yavin E. 
Published: October 2006

AbstractThe protein composition of the particulate fraction of dissociated foetal rat cerebral cells during maturation in culture was investigated. SDS polyacrylamide gel electrophoresis showed a general decrease in the histonal components and significant changes in composition of a group of polypeptides with molecular weights ranging from 42 to 60 K. Two of these polypeptides coelectrophoresed with tubulin and actin whereas a 48 K polypeptide comigrated with the major component of the Wolfgram myelin protein. Its relative quantity appeared to approach a plateau after 8 days in culture. The myelin basic and proteolipid proteins were below detection levels in cultured cells at any time point investigated. A group of polypeptides with estimated molecular weights of 47, 51 and 52 K possibly representing synaptic proteins increased with time in culture. The appearance of a prominent band (60 K) in brain cultures and in other cells of divergent origin was demonstrated. This protein may be related to the process of cell adaptation to culture conditions. The developmental changes in the protein profile are discussed in the context of an in vitro myelinogenesis and synaptogenesis and compared with whole brain particulate and subcellular fractions.
PROTEIN and RNA SYNTHESES and PRECURSOR UPTAKE WITH ISOLATED NERVE and GLIAL CELLS
Authors: Yanagihara T. 
Published: October 2006

AbstractProtein and RNA syntheses were investigated with bulk isolated nerve and glial cells from rabbit brain. For polypeptide synthesis, ‘intact’ cells were incubated with [3H]leucine under various conditions and the results were compared with those of polyribosomal polypeptide synthesis. For RNA synthesis ‘intact’ cells were incubated with [3H]uridine or [3H]guanosine and the results were compared with those of DNA‐dependent RNA polymerase assay. The bulk isolated ‘intact’ nerve cells were more active in protein synthesis than the ‘intact’ glial cells, while the latter synthesized RNA more actively than the former, although both polyribosomal polypeptide synthesis and DNA‐dependent RNA polymerase activity were higher with the nerve cells, indicating a higher potential for the nerve cells. The observed discrepancy of RNA synthesis was explained by the significantly less active uptake of nucleosides with the nerve cells. Both protein and RNA syntheses with ‘intact’ cells were sensitive to hypoxic or glucose‐deficient conditions. While both the nerve and glial cells were sensitive to hypoxia to a similar extent, the nerve cells were more sensitive to glucose deficiency. It was suggested that the bulk isolated nerve and glial cells still retain certain integral cell functions as viable cells, and can be utilized for various physiological and pharmacological investigations provided caution is exercised in their application and in the interpretation of the results.
CORRELATIONS BETWEEN A FLUORIMETRIC and MASS FRAGMENTOGRAPHIC METHOD FOR THE DETERMINATION OF 3‐METHOXY‐4‐ HYDROXYPHENYLACETIC ACID and TWO MASS FRAGMENTOGRAPHIC METHODS FOR THE DETERMINATION OF 3‐METHOXY‐4‐ HYDROXYPHENYLETHYLENE GLYCOL IN CEREBROSPINAL FLUID
Authors: Muskiet F. A. J. , Jeuring H. J. , Korf J. , Sedvall G. , Westerink B. H. C. , Teelken A. W. , Wolthers B. G. 
Published: October 2006

AbstractOne‐hundred and twenty‐two lumbar cerebrospinal fluid (CSF) samples were assayed for 3‐methoxy‐4‐hydroxyphenylacetic acid (HVA) by both a fluorimetric and mass fragmentographic method. The correlation coefficient (cc) and residual standard deviation (Syx) of the results were calculated as 0.966 and 23.3 ng/ml, respectively. If only samples containing less than 100ng/ml of HVA were considered, somewhat different values for cc and Syx were found (0.854 and 10.0 ng/ml, respectively). The data obtained by the fluorimetric method were consistently 17% lower than those obtained by the mass fragmentographic method. Spiking experiments resulted in 96.5 ± 7.8% recovery for the fluorimetric method, whereas the use of a deuterated internal standard was found to compensate completely for losses in the mass fragmentographic method. In addition the correlation between two different mass fragmentographic methods for the simultaneous determination of HVA and 3‐methoxy‐4‐hyd‐roxyphenylethylene glycol (MOPEG) in CSF was studied. The measurements were performed in different laboratories and resulted in correlation coefficients of 0.941 and 0.940 and residual standard deviations of 7.6 and 1.0 ng/ml for HVA and MOPEG, respectively. From all data we conclude that mass fragmentographic methods for the determination of catecholamine metabolites in CSF are superior to fluorimetric methods because of their selectivity, reproducibility and accuracy.
THE CHARACTERIZATION OF SPHINGOLIPIDS OF OLIGODENDROGLIA FROM CALF BRAIN
Authors: Abe Toshiaki , Norton William T. 
Published: October 2006

Abstract— Purified oligodendroglia isolated from bovine brain white matter were found to contain, in addition to galactosylceramide, sulfatide and sphingomyelin, significant quantities of glucosylcerai‐mide, dihexosylceramide and esterified galactosylceramide. These sphingolipids were isolated and quan‐titated and their fatty acid and long chain base patterns compared with those from sphingolipids isolated from bovine myelin, white matter and gray matter.The minor glycosphingolipids, glucosylceramide, dihexosylceramide and esterified galactosylceramide, constituted a higher percentage of glial lipids than of myelin lipids. Glucosylceramide accounted for 12% of the total glial monohexosylceramide fraction and 0.8% of total lipids; dihexosylceramide was 0.9% of total glial lipids. Both of these lipids had small quantities of α‐hydroxy fatty acids. The unsubstituted fatty acids of glucosylceramide were mostly short chain (16 and 18 carbons) and were different from those of the dihexosylceramides which were a mixture of short and long chain. The hydroxy acids of each of these lipids were, however, similar and resembled those of galactosylceramide.The fatty acid patterns of galactosylceramide, sulfatide and sphingomyelin from glial cells resembled those of the corresponding lipids from myelin and white matter. The amide‐linked acids of esterified galactosylceramide contained both unsubstituted and α‐hydroxy chains. Their patterns were not identical to those of galactosylceramide, but were similar in all brain fractions.With the exception of sphingomyelin and dihexosylceramide, which contained small amounts of C20‐sphingosine, all sphingolipids analyzed contained mostly sphingosine and dihydrosphingosine.We conclude that the distribution of sphingolipids in the oligodendroglia is characteristic, but the lipophilic residues of these lipids are not cell‐specific.
THE INCORPORATION OF [1‐14C]LINOLENATE INTO LIPIDS OF DEVELOPING RAT BRAIN DURING ESSENTIAL FATTY ACID DEPRIVATION
Authors: Dwyer Barney , Bernsohn Joseph 
Published: October 2006

Abstract— Twenty‐one‐day old essential fatty acid (EFA) deprived rats incorporated about twice the radioactivity from [1‐14C]linolenate into brain lipid fractions as did controls. At 5 min after injection, 2/3 of the radioactivity was associated with the less polar lipid fraction of both control and EFA deprived animals. By 30 min after injection, 70% of the radioactivity was in the phospholipid fraction. This value increased to 90% at later time points.The specific activity of brain phospholipids from EFA deprived rats was always greater than that of controls. This held true for the individual phosphatide fractions also. In general, phosphatidylcholine (PC) was labeled most rapidly. With increasing time intervals, radioactivity was transferred to phospha‐tidylethanolamine (PE) and phosphatidylserine + phosphatidylinositol (PS + PI).The transfer of fatty acid radioactivity into phospholipid and the distribution of radioactivity among individual phosphatides did not appear to be affected by the dietary state. However, the total amount of radioactivity incorporated was related to the amount initially retained by brain after injection. Our data suggest that one or more components of the less polar lipid fraction may act as a ‘trap’ or reservoir for fatty acids which are required for phospholipid synthesis.
AXONAL TRANSPORT OF PROTEIN IN THE OPTIC NERVE OF OCTOPUS VULGARIS, LAM.
Authors: Cimarra Patrizia , Giuditta Antonio 
Published: October 2006

Abstract— The presence of an axonal flow of proteins has been investigated in the optic nerve and lobe of Octopus vulgaris up to 5 days after the intraocular injection of [3H]leucine. In each of these regions and in the posterior half of the eye the content of radioactivity has been determined in the TCA‐soluble fraction and in the saline‐soluble and insoluble protein fractions.After subtraction of the values of the control side, the concentration of radioactive proteins in the optic nerve and lobe of the injected side was found to increase according to a triphasic pattern. An initial phase of fast increase was followed by a period of essentially steady values and, eventually, by a second phase of less rapid but more prolonged increment. In both regions the per cent of radioactive soluble proteins increased after the completion of the first phase.
CHARACTERIZATION OF BRAIN RIBONUCLEOPROTEIN PARTICLES
Authors: Mahony James B. , Brown Ian R. 
Published: October 2006

Abstract— Brain RNP particles were characterized to determine whether they play a role in the regulation of brain protein synthesis. RNP particles were isolated from the postribosomal supernatant of cerebral hemispheres of young rabbits, employing conditions which minimize adventitious protein‐RNA interactions. Brain RNP particles consist of a different set of proteins compared to proteins associated with either 40 and 60s ribosomal subunits or polysomal mRNA. Poly(A+)mRNA from brain RNP particles stimulates the incorporation of [35S]methionine in a wheat embryo cell‐free system and codes for a different set of proteins compared to poly(A+)mRNA isolated from polysomes (with some overlap; i.e. mRNA coding for brain‐specific S100 protein is present in both RNP particles and polysomes).Addition of total brain RNP particles to a cell‐free wheat embryo system inhibits the endogenous incorporation of [35S]methionine. Total RNP particles were fractionated by sucrose density gradient centrifugation into a‘light’and a‘heavy’fraction. The light RNP fraction inhibited while the heavy RNP fraction stimulated protein synthesis in the wheat embryo cell‐free system. Analysis of the protein composition of fractionated RNP particles revealed that the light and heavy RNP particles contained different sets of proteins. Together these results suggested that one class of brain RNP particles may contain a translational inhibitor and may be involved in the regulation of protein synthesis in the brain.
STABILITY OF SYNAPTOSOMAL GABA LEVELS AND THEIR USE IN DETERMINING THE IN VIVO EFFECTS OF DRUGS: CONVULSANT AGENTS
Authors: Wood J. D. , Russell M. P. , Kurylo E. , Newstead J. D. 
Published: October 2006

Abstract—The stability of the GABA content of synaptosomal‐enriched fractions was evaluated by two approaches. Firstly, the addition of 10−3m‐aminooxyacetic acid to the homogenizing medium totally inhibited the GABA‐degrading enzyme in the fractions but did not affect the GABA levels. This indicated that GABA was not being metabolized during the normal preparation of the synaptosomal‐enriched fraction. Secondly, when synaptosomal‐enriched fractions were re‐fractionated by discontinuous density gradient centrifugation, the GABA contents of the fractions before and after the second fractionation were very similar provided they were expressed on a per mg protein basis. It was therefore concluded that the GABA content of the organelles was not subject to change during the fractionation procedures. On the basis of these findings and others it was suggested that the synaptosomal‐enriched fraction could be used as a model to evaluate drug‐induced changes in GABA levels in nerve endings. In vivo experimentation indicated that the convulsant agents hydrazine, isonicotinic acid hydrazide and aminooxyacetic acid brought about similar decreases in the GABA content of the synaptosomal‐enriched fractions prepared from tissue at the onset of seizures despite the fact that no correlation was observed between seizure activity and whole brain GABA levels.
THE BINDING INTERACTION BETWEEN α‐LATROTOXIN FROM BLACK WIDOW SPIDER VENOM AND A DOG CEREBRAL CORTEX SYNAPTOSOMAL MEMBRANE PREPARATION
Authors: Tzeng Mu‐Chin , Siekevitz Philip 
Published: October 2006

Abstract—The major toxin of black widow spider venom, α‐latrotoxin, can be iodinated with 125I with hardly any loss in biological activity. The radioactive toxin could bind specifically to a dog cerebral cortex synaptosomal membrane preparation but not to a dog liver plasma membrane preparation. The bound protein could be recovered from the neuronal membrane preparation in an unchanged form. Non‐specific binding was only 6–10% of the total binding. The protein nature of the presumed receptor was indicated by the complete inhibition of the binding by either heating the membrane preparation at 70°C or treating the membrane with trypsin. Pre‐incubation with 2%β‐mercaptoethanol also completely inhibited the binding, while 70% inhibition was observed after pre‐treatment with 10m M‐EDTA or EGTA. From plots of the equilibrium binding data, it could be ascertained that the binding is non‐cooperative, with an apparent equilibrium dissociation constant, K1, of 1.0 nM. Kinetic data gave an apparent association rate constant of 8.2 × 105 M−1 s−1. Dissociation followed a biphasic exponential with rate constants of 1.4 × 10−3 and 5.2 × 10−5s−1 corresponding to half‐lives of 8.2 min and 3.7 h. Possible schemes for the binding interaction were proposed. Based on the present results and on previous results which indicated that α‐latrotoxin causes the release of all neurotransmitters and a depletion of the synaptic vesicle population in vertebrate synapses, a hypothetical mechanism of the action for the toxin was proposed, involving the binding of the toxin to a membrane protein receptor which interacts with filamentous proteins linking the synaptic vesicles to the axolemma.
ELEVATED CONCENTRATIONS OF HISTAMINE IN THE RAT BRAIN
Authors: Orr Edward L. , Eichelman Burr 
Published: October 2006

Abstract—Whole brain concentrations of histamine (Hm) in the rat were measured with a sensitive and specific single‐isotope enzymatic microassay and found to be elevated about 2‐fold in rats killed by focused microwave irradiation compared with rats killed by decapitation. However, regardless of the method of killing, whole brain Hm concentrations were elevated about 4‐fold when the brains were homogenized in 12.5 vol vs 2.5 vol of water or phosphate buffer. Homogenization of brain regions in 12.5 vol of water resulted in Hm concentrations that were about 10 times greater than previously reported values (except in the hypothalamus). Since (1) the‘extra’Hm could be extracted from pellets of low volume homogenates, and (2) synthesis of Hm is not likely to occur through an increase in the volume of water or buffer used for homogenization, we suggest that the elevated concentrations of Hm seen after high volume homogenization of brain tissue are due to a more complete extraction of Hm from brain tissue, and not to an artifactual production of this amine from its precursor (histidine) or some other compound(s).
UPTAKE AND RELEASE OF TAURINE FROM CEREBRAL CORTEX SLICES AND THEIR SUBCELLULAR COMPARTMENTS
Authors: WHELER G. H. T. , BRADFORD H. F. , DAVISON A. N. , THOMPSON E. J. 
Published: October 2006

Abstract—Cortex slices, synaptosomes and C‐6 glioma cells were used to study [35S]taurine uptake and its electrically‐stimulated release. After exposure to taurine at two concentrations, the synaptosome preparation subsequently derived from the slices contained 41% of the particle‐bound taurine and 16% of the total in the tissue. The uptake of [14C]GABA by C‐6 glioma cells was inhibited 3‐fold more by β‐alanine than by l‐DABA, whilst synaptosome preparations showed the opposite pattern, l‐DABA being 2 or 3 times more effective than β‐alanine. [35S]Taurine uptake inhibition by l‐DABA was low for synaptosomes and C‐6 glioma, whereas β‐alanine showed considerable effect on C‐6 glioma (41%) and slices of white matter (ependyma; 50%). Synaptosome preparations showed little effect with β‐alanine. When 30 min rather than 5 min incubations were employed, β‐alanine depressed [35S]taurine uptake by cortex slices by 30%. Taurine was taken up by a calcium‐dependent mechanism and subcellular fractionation indicated that the synaptosome fraction showed losses commensurate with the net taurine release when low stimulation currents were used.
Changes in Prolyl Endopeptidase During Maturation of Rat Brain and Hydrolysis of Substance P by the Purified Enzyme
Authors: Kato Takeshi , Nakano Tamotsu , Kojima Kohichi , Nagatsu Toshiharu , Sakakibara Shumpei 
Published: October 2006

Abstract: We determined changes in prolyl endopeptidase activity in developing rat brain. A new and highly sensitive fluorogenic substrate, 7‐(succinyl‐Gly‐Pro)‐4‐methylcoumarinamide, was used for determination of the enzyme activity. The enzyme activity per brain increased until 2 weeks of age, and then decreased during maturation. The enzyme was purified about 7800‐fold from the brain of the rat at 2 or 3 weeks of age. The enzyme has a pH optimum of 5.8 to 6.5, and an approximate molecular weight of 70,000. The enzyme activity was completely inhibited by low concentrations of diisopropylfluorophosphate and partially inhibited by high concentrations of phenylmethanesul‐phonylfluoride, which are potent serine protease inhibitors. Moreover, thiolblocking agents and some heavy metals also have a strong effect on the activity. Bacitracin was found to be a potent inhibitor, with an IC50 value of 2.5 × 10−6m at 0.5 mm of the substrate. The enzyme was proved to hydrolyze the NH2‐terminal tetrapeptide, Arg1‐Pro2‐Lys3‐Pro4, from substance P to produce the heptapeptide, Gln5‐Gln6‐Phe7‐Phe8‐Gly9‐Leu10‐Met11‐CONH2. The Km value of the hydrolysis of substance P was 1.0 mm. This enzyme may be related to the regulation of substance P in the brain, and to the development of neurones by forming the tetrapeptide because the tetrapeptide has almost the same effect as substance P on the neurite extension of neuroblastoma.
Heterogeneity of Benzodiazepine Receptors in the Central Nervous System Demonstrated with Kenazepine, an Alkylating Benzodiazepine
Authors: Williams Evan F. , Rice Kenner C. , Paul Steven M. , Skolnick Phil 
Published: October 2006

Abstract: Binding studies using the alkylating benzodiazepine kenazepine strongly suggest the existence of several populations of benzodiazepine receptors in the CNS. Kenazepine reacts noncompetitively and irreversibly with some receptors and competitively (reversibly) with others. Cerebellum contains the largest proportion (approx. 80%) of the noncompetitive type, while hippocampus and cortex contain a preponderance of competitive‐type receptors (approx. 80 and 50%, respectively). The Hill coefficients for kenazepine are approx. 0.7 in cortex and cerebellum, and near unity in dorsal hippocampus. Different populations of benzodiazepine receptors may mediate different physiologic and pharmacologic effects in vivo.
Cyclic Guanosine Monophosphate in Primary Cultures of Glial Cells
Authors: Bloch‐Tardy M. , Fages C. , Gonnard P. 
Published: October 2006

Abstract: Cyclic GMP was found in primary cultures of glial cells obtained by dissociation of newborn mouse brain hemispheres. Its basal level (0.52 pmoles/mg cell protein) was as high as that found in adult mouse brain cortex but 10 times lower than in cerebellum. When glia were grown in the presence of dBcAMP, astrocytes changed their morphology; cGMP level increased and reached about 8 to 10 times the basal value. This increase was dose dependant with cAMP and was enhanced by the presence of 5mM Theophylline. Two hypothesis are discussed, either a direct action of cAMP on glial cGMP metabolism or an indirect one on the protein activator of cGMP phosphodiesterase.