bluuebunny/crossref_metadata_2025_split huggingface dataset:
RATE OF PROTEIN RENEWAL IN SPINAL MOTONEURONS OF ADOLESCENT AND OLD RATS
Authors: Jakoubek B. , Gutmann E. , Fischer J. , Babický A. 
Published: October 2006

Abstract—The rate of incorporation of [35S]methionine and the turnover rate of proteins in spinal motoneurons were studied in adolescent and old rats. The radioactivity of proteins was estimated by quantitative autoradiography and direct counting of beta radiation from samples of neurons isolated by free hand dissection. Both methods showed that the rate of incorporation into spinal motoneurons was significantly lower in old animals. By measuring the turnover rate of proteins in spinal motoneurons at least two protein components could be distinguished by their different turnover rates. The short‐lived component had an average half‐life of 2‐2‐2‐8 days, the long‐lived protein component had an average half‐life of 27‐38 days. Neither in the short‐lived component, nor in the long‐lived component was it possible to detect a significant difference between adolescent and old rats.
SOME PROPERTIES OF ISOLATED NEURONAL CELL FRACTIONS
Authors: Rose S. P. R. , Sinha A. K. 
Published: October 2006

Abstract— 1. Histochemical evidence was presented illustrative of the composition of neuronal and neuropil (‘glial’) fractions isolated according to a previously published procedure. The neuropil refers to all cortical tissue other than neuronal perikarya.2. On the basis of cell counts and of DNA content, an average cell mass of 100‐110 pg was calculated for cells in the neuronal fraction. Eight per cent of the total DNA was recovered in the neuronal fraction.3. Both fractions synthesized ATP in vitro. Concentrations after 60 min incubation with glucose were: neuropil, 7–36 μmoles/mg protein; neuronal, 12–31 μmoles/mg protein.4. Osmotic shock or homogenization resulted in changes in turbidity of the cell fractions which were interpreted as indicative of loss of cell structure. The free pool amino acids glutamate, glutamine, GABA, aspartate and alanine were retained in the precipitable material through several washes with isotonic solutions. Homogenization released 72 per cent of the neuronal and 68 per cent of the neuropil amino acids into the supernatant, but only 37 per cent and 19 per cent respectively of the protein.5. By contrast with earlier reports, K+ accumulation has now been demonstrated in both neuronal and neuropil fractions. After incubation with glucose, K+ level were calculated as being 80 per cent of slice in the neuronal, and 65 per cent in the neuropil fraction. These results, and those of the osmotic shock experiments, were taken as indicative of the retention of some cell structure.6. By comparison, cell fractions prepared by other procedures, using acetone‐glycerol‐water or tetraphenylboron for tissue disaggregation, produced preparations with limited metabolic capabilities; oxygen uptake, CO2 and lactate production were all lowered substantially.
METABOLISM OF GLUCOSE AND GLUTAMATE BY SYNAPTOSOMES FROM MAMMALIAN CEREBRAL CORTEX
Authors: Bradford H. F. , Thomas A. J. 
Published: October 2006

Abstract—(1) Synaptosomes incubated in high sodium, low potassium media showed high linear respiration in the presence of glucose which was converted into lactate, aspartate, glutamate, glutamine, alanine and GABA during 1 hr incubation periods.(2) Total conversion of glucose into most of these substrates over the incubation period was similar in synaptosomes and cortex slices. Half the lactate and only a small fraction of the glutamine made by slices was formed by synaptosomes.(3) Pool sizes of amino acids in cortex slices after incubation with glucose were, in general, higher than in synaptosomes, glutamate and glutamine being four‐fold higher in slices.(4) Most of the amino acids made from glucose by synaptosomes were contained within their structure and not lost to the medium.(5) Glutamate was actively metabolized by synaptosomes to aspartate, glutamine, alanine and GABA. The specific radioactivities of the amino acids (except glutamine) after 1 hr incubation, approached that of the glutamate.(6) Pyridoxal phosphate added to the incubation medium increased GABA production from glutamate but not from glucose.
SEDIMENTATION ANALYSIS OF RIBONUCLEIC ACID EXTRACTED FROM ISOLATED MAUTHNER NERVE FIBRE COMPONENTS
Authors: Edström A. , Edström J.‐E. , Hökfelt T. 
Published: October 2006

Abstract— Segments of spinal cords from goldfish or from carp were incubated in vitro in the presence of RNA precursors for varying periods of time. Mauthner nerve fibres were isolated from the fresh unfixed tissue, or, for the separate analyses of axon and myelin sheath, from the fixed spinal cord.The myelinated Mauthner fibre isolated from the incubated spinal cord showed RNA synthesis. A considerable part of the material sedimented at 4S, but part of the nucleic acid was recovered at higher sedimentation values, up to 30S. Newly synthesized RNA was extracted from the isolated myelin sheath as well as from the axon. Isolated myelinated Mauthner fibres were also incubated in vitro with RNA precursors. In this case incorporation occurred exclusively in material sedimenting at 4S or lower. The turnover rate for RNA from the fibre was of a higher order than that of the bulk of RNA from the spinal cord. The findings of RNA synthesis in these tissue components lacking nuclei could possibly be explained as owing to mitochondria.Studies by electron microscopy demonstrated the extent of purity of the isolated components and it was found that contamination was so small as to make it unlikely that the RNA investigated originated in contaminating tissue.
UPTAKE OF CALCIUM BY SUBCELLULAR FRACTIONS ISOLATED FROM OUABAIN‐TREATED CEREBRAL TISSUES
Authors: Stahl W. L. , Swanson P. D. 
Published: October 2006

Abstract— Slices of cerebral cortex were incubated in medium containing 0·75 or 2·8 mM 45CaCl2, in the presence or absence of 0·01–0·1 mm‐ouabain. Ouabain induced accumulation of calcium by slices to a maximum of 4 μmoles/g of tissue/hr (0·75 mm‐CaCl2 in the medium) and to 8 μmoles/g of tissue/hr (2·8 mm‐CaCl2 in the medium). Accumulation of Ca2+ occurred more slowly than loss of K+ from the slices and more closely resembled the pattern of Na+ uptake.Mitochondrial fractions isolated from ouabain‐treated slices contained significantly more calcium than controls. Inclusion of EDTA in the homogenization medium resulted in decreased amounts of particulate‐bound calcium.The effect of ouabain on accumulation of calcium is discussed with regard to possible relationships to processes of active and passive transport.
FUCOSE INCORPORATION INTO GLYCOPROTEINS OF MOUSE BRAIN
Authors: Zatz M. , Barondes S. H. 
Published: October 2006

Abstract—Radioactive fucose was incorporated into glycoproteins of brain in vivo. After intracerebral administration of this precursor, radioactive glycoproteins were the sole detectable product. The glycoproteins formed appeared to have a slow turnover but this was due, at least in part, to re‐utilization of fucose released from degraded glycoproteins. Incorporation of fucose into glycoproteins differed from that of glucosamine, since a much smaller proportion of the radioactive fucose was incorporated into soluble glycoproteins. Fucose was rapidly incorporated into glycoproteins of nerve endings, although there was relatively little incorporation into glycoproteins associated with the soluble component of the nerve‐ending fraction. As found in previous studies with glucosamine, soluble glycoproteins of nerve endings turned over relatively rapidly. Pretreatment with acetoxycycloheximide markedly inhibited incorporation of fucose into glycoproteins of brain. In contrast to the results with glucosamine, comparable inhibition was observed for fucose in all subcellular fractions of brain including the particulate and soluble components derived from the nerve‐ending fraction.
SYNTHESIS OF NUCLEAR RNA IN NERVE AND GLIAL CELLS
Authors: Løsvtrup‐Rein Huguette 
Published: October 2006

Abstract—Tritium‐labelled RNA precursors were injected at 30 min intervals into the fourth ventricle of rats or rabbits. After 4 h the nuclei from neurones, astrocytes, and other glial cells were isolated and RNA extracted. Investigations were performed in order to establish optimum conditions for RNA extraction from this particular material.The sedimentation patterns obtained in sucrose gradients were similar to those of nuclear RNA from other mammalian tissues and showed the presence of RNA species with high specific activities in the region of the gradient between 10S and 16S and above 28S. All three types of nuclei contained a 45S and a 38S RNA. Moreover, a 32S component could be identified in astrocytic nuclei, a 35S fraction in neuronal nuclei, and both a 32S and 35S RNA in nuclei from glial cells. The nuclei from the various cell types also differ with respect to the rate of incorporation of the label into the nuclear RNA, being four times higher in astrocytic and neuronal nuclei than in those derived from the other glial cells.
GLYCOPROTEIN METABOLISM IN DEVELOPING MOUSE BRAIN1
Authors: Dutton G. R. , Barondes S. H. 
Published: October 2006

Abstract—Incorporation of [14C]fucose or [14C]glucosamine into the glycoproteins of developing mouse brain was studied using polyacrylamide gel electrophoresis. Between 1 and 10 days after birth two fractions of soluble glycoproteins were extensively labelled, but by 15 days after birth incorporation into these fractions was no longer prominent. These glycoproteins have apparent molecular weights in the range of 150,000‐250,000, as estimated by the electrophoretic procedure. The more rapidly migrating fraction has a half‐life of about 1 week whereas the other is far more stable.
TOPOGRAPHICAL AND SUBCELLULAR LOCALIZATION OF CHOLINE ACETYLTRANSFERASE IN RAT HIPPOCAMPAL REGION
Authors: Fonnum F. 
Published: October 2006

Abstract—Choline acetyltransferase (ChAc) was localized in discrete layers in hippocampus regio superior and in area dentata. The highest activity in hippocampus was found in a narrow infrapyramidal zone, but high activities were also observed in the rest of stratum oriens and in stratum pyramidale. In area dentata the highest activities were found in a narrow supragranular zone and in hilus fasciae dentatae. The localization corresponded very closely to that of acetylcholinesterase. The main part of ChAc activity was confined to the synaptosome fraction. The results are compatible with the view that pyramidal and granular cells are excited by cholinergic boutons, mainly located on the basal or apical dendrites near the somata.
[U‐14C]GLUCOSE METABOLISM OF THE PERFUSED CAT BRAIN WITH BLOOD FLOW DISTURBANCES1
Authors: Watanabe S. , Oisuki S. , Mitsunobu K. , Sannomiya T. , Okumura N. 
Published: October 2006

Abstract—In order to study changes of the glycolytic‐respiratory system and amino acid metabolism associated with blood flow disturbance, the cat brain perfusion was conducted with artificial blood containing [U‐14C]glucose and the results were compared with those of standard perfusion keeping the cerebral blood flow at constant rate. The findings of the present study are briefly summarized:(1) In blood flow disturbance there was observed an accumulation of lactate just as seen in the low functional state observable in the standard perfusion. However the increase in relative specific activity of lactate was not so marked as the rise in cerebral lactate content, and this indicates that there is an increase of lactate production from substrates other than glucose as well as an increase of net flow of glucose carbon to lactate.(2) In blood flow disturbance relative specific activities of glutamate, aspartate, glutamine and respiratory CO2 were decreased as compared with those in the brain of high functional state. The relative specific activity of GABA in the reduced blood flow brain was at the same level as that of the brain at high functional state and it was higher than the relative specific activity of glutamate.(3) The relative specific activity and content of alanine were increased in the low function brain with standard perfusion.
THE OCCURRENCE OF TWO MYELIN BASIC PROTEINS IN THE CENTRAL NERVOUS SYSTEM OF RODENTS IN THE SUBORDERS MYOMORPHA AND SCIUROMORPHA
Authors: Martenson R. E. , Deibler Gladys E. , Kies Marian W. 
Published: October 2006

Abstract—Extracts containing myelin basic proteins have been prepared from CNS tissue of representatives of the three suborders of Rodentia—Myomorpha, Hystricomorpha and Sciuro‐morpha. Analyses of the extracts by electrophoresis at low pH showed that one type (L) of myelin basic protein is present in the CNS of all of the rodents examined (rat, mouse, hamster, guinea pig, chinchilla, prairie dog, woodchuck and squirrel). This protein is comparable in molecular size and charge to the CNS myelin basic proteins found in several other mammalian orders. In the CNS of the myomorphs (rat, mouse, hamster) and sciuro‐morphs (prairie dog, woodchuck, squirrel) there is an additional type (S) of myelin basic protein of higher cathodic mobility and smaller molecular size. This additional protein is absent from the CNS of the hystricomorphs (guinea pig, chinchilla). These findings indicate that the presence of two myelin basic proteins originally reported in the CNS of the inbred rat is not an anomaly of inbreeding. These data further suggest that the presence of a single L‐type CNS myelin basic protein might be a general characteristic of hystricomorphs, while the presence of both L‐ and S‐type CNS myelin basic proteins might be a general characteristic of the myomorphs and sciuromorphs.Analyses by electrophoresis at low pH failed to reveal differences in mobility among either the L‐type or the S‐type CNS myelin basic proteins of the different species. In contrast, when electrophoresis was carried out cathodically at high pH, species‐related differences in mobility were observed among the L‐ and S‐type CNS myelin basic proteins.
STIMULATION OF BRAIN SEROTONIN SYNTHESIS BY DIBUTYRYL‐CYCLIC AMP IN RATS
Authors: Tagliamonte A. , Tagliamonte P. , Forn J. , Perez‐Cruet J. , Krishna G. , Gessa G. L. 
Published: October 2006

AbstractCyclic AMP and dibutyryl‐cyclic AMP, a derivative of cyclic AMP resistant to phosphodiesterase inactivation, were injected into the lateral ventricles of rats. These nucleotides did not change the level of brain 5‐HT but increased the brain level of its principal metabolite, 5‐hydroxyindoleacetic acid. Cyclic AMP was less potent than dibutyryl‐cyclic AMP. Butyrate and 5′‐AMP were inactive. The effect of dibutyryl cyclic AMP on 5‐HT metabolism was studied both in vivo and in vitro. The rate of synthesis of 5‐HT was measured by the rate of accumulation of 5‐hydroxyindoleacetic acid after the transport of this acid out of the brain was blocked with probenecid. The rate of synthesis of brain 5‐HT increased from 0‐38 μg/g/h in control rats to 0‐65 μg/g/h after dibutyryl‐cyclic AMP. In addition cyclic AMP and dibutyryl‐cyclic AMP markedly increased brain tryptophan, while AMP was inactive. Since brain tryptophan hydroxylase has a Km for its substrate that is much higher than the concentrations of tryptophan normally present in the brain, it is likely that the increase in the rate of synthesis of brain 5‐HT is secondary to the cyclic AMP induced increase in the levels of brain tryptophan. In vitro studies revealed that dibutyryl‐cyclic AMP increased the uptake of radioactive labelled tryptophan into slices of rat brain stem and the formation of 5‐HT and 5‐hydroxyindoleacetic acid.
PITFALLS IN THE USE OF RAPID FREEZING FOR STOPPING BRAIN AND SPINAL CORD METABOLISM IN RAT AND MOUSE
Authors: Swaab D. F. 
Published: October 2006

AbstractThe rate at which the metabolism is stopped by means of freezing in Freon‐12 (–150°C) was studied in various areas of the rat and mouse CNS, using changes in temperature and levels of glucose and lactate as parameters for this rate. The rat cerebral cortex was frozen after 0.5 min while the hypothalamus reached 0°C after more than 1.5 min. The skin on the skull was found to be the most important temperature isolator for the cortex. Substrate levels can be studied in this area only if this piece of skin is removed previously.In the mouse, the cerebral cortex was frozen after 6 s, the hypothalamus after 0.5 min. The lumbar level of the mouse spinal cord was frozen after 15 s, the cervical level only after 47 s. Liquid nitrogen alone cooled the mouse cerebral cortex at least as fast as did Freon at its melting point. A gradual decrease from dorsal to ventral was observed in the glucose level of the molecular layer of the mouse cerebellum. The existence of a freezing front, moving slowly from dorsal to ventral, and its consequences for the measured levels of biologically labile substrates, are discussed.
INCORPORATION IN VIVO OF INTRACISTERNALLY INJECTED 33P1, INTO PHOSPHOLIPIDS OF RAT BRAIN1
Authors: Friedel R. O. , Schanberg S. M. 
Published: October 2006

AbstractThe incorporation in vivo of intracisternally injected 33Pi into individual phospholipids of rat brain was studied at intervals ranging froml min to 8 days after injection. At 1 min after injection there was significant incorporation of “Pi into PA and the phosphoino‐sitides, with the pattern of incorporation TPI > DPI > PA > PI. There was a 10‐min lag period before significant labelling of the remaining phospholipids. In general, the extent of incorporation measured during the first 8 days after injection paralleled the quantity of each phospholipid in the brain, except for the values of PA and the phosphoinositides which were all higher than would be predicted by this criterion and reached maximal incorporation sooner than the other phospholipids. The possible correlation of the high metabolic activities of PA and the phosphoinositides with neuronal function, as well as the importance of short‐term experiments in clarifying such relationships are discussed.
ORNITHINE DECARBOXYLASE ACTIVITY IN DEVELOPING RAT BRAIN1
Authors: Anderson T. R. , Schanberg S. M. 
Published: October 2006

Abstract—Total ornithine decarboxylase (ODC) (EC 4.1.1.17) activity per rat brain was elevated markedly from 14 days after conception to 12 days postnatum. ODC activity in the brainstem was very low and changed little during postnatal development. Activity in the cerebral hemispheres declined from a high level at birth to the low adult level by 8 days postnatum. Conversely activity in the cerebellum increased markedly from 3 days until 11 days postnatum, then suddenly decreased. Hence, the periods of greatest ODC activity paralleled those of maximal cell proliferation in each brain region. During perinatal brain development ODC activity changed considerably; it declined at about one day prior to term, and then increased rapidly to its highest level of activity at 4 h postnatum. Premature birth by caesarian section or lack of maternal care and nutrition did not affect this early postnatal response. The postnatal burst in ODC activity appears to be unique for brain tissue, since this response did not occur in heart, skeletal muscle or liver.Data from studies in which portions of fractions characterized by high or low enzymatic activity, respectively, were mixed or in which the supernatant enzyme fraction was dialysed are not consistent with the presence of direct inhibitors or activators of the enzyme. In addition, administration of cycloheximide to newborn rats abolished the 4‐h postnatal burst in ODC activity. Our results suggest that the increase in ODC activity reflects enzyme synthesis de novo.
EFFECTS OF 5,6‐DIHYDROXYTRYPTAMINE ON MONOAMINERGIC NEURONES IN THE CENTRAL NERVOUS SYSTEM OF THE RAT
Authors: Baumgarten H. G. , Evetts K. D. , Holman R. B. , Iversen L. L. , Vogt Marthe , Wilson Gay 
Published: October 2006

Abstract—The injection of 50 μg of 5,6‐dihydroxytryptamine (5,6‐HT) into a lateral ventricle of the rat depleted the spinal cord and various regions of the brain of indoleamines (presumably 5‐HT) and 5‐hydroxyindole acetic acid. The concentrations of 5‐HT were measured by two different methods: the formation of a fluorescent derivative with o‐phthalaldehyde, and the native fluorescence in hydrochloric acid. When the results of both methods were compared on the pons and medulla 4 days after injecting 5,6‐HT, the loss in indoleamine appeared to be greater when o‐phthalaldehyde was used. This suggests that the two methods may be measuring different compounds. According to both methods, the loss of 5‐HT persisted for several days after the injection of 5,6‐HT, but by 2 months 5‐HT concentrations (measured only by the native fluorescence procedure), had recovered to near‐normal values. The depletion of 5‐HT was most pronounced in regions adjacent to the ventricular system and in the spinal cord. Initially, caudate and septum were more affected on the side of the injection, and later showed some permanent atrophy. The injection of up to 50 μg of 5,6‐HT did not lead to any significant loss of noradrenaline or dopamine from the brain, or to any reduction in the activity of the enzyme tyrosine hydroxylase. The drug was a potent inhibitor of the uptake of [3H]5‐HT by brain slices, but was less effective in inhibiting catecholamine uptake systems. These observations suggest a preferential action on tryptaminergic neurones. Larger doses of 5,6‐HT caused a loss of catecholamines and tyrosine hydroxylase from the brain, and were severely toxic.
EFFECTS OF IMIDAZOLEACETIC ACID ON BRAIN AMINO ACIDS AND BODY TEMPERATURE IN MICE1
Authors: Tunnicliff G. , Wein J. , Roberts E. 
Published: October 2006

AbstractFree amino acids have been studied in the brains of fasted mice (18 h) injected intraperitoneally with a 3 mmol/kg dose of imidazole‐4‐acetic acid (IMA). Groups of mice were killed by cervical dislocation and their brains were removed before injection or at 5, 15, 30, 60, 90 and 120 min after injection and treated immediately with perchloric acid. Amino acid analyses were performed on the perchlorate extracts. Of the 16 amino acids evaluated quantitatively, only glutamic acid and glutamine showed progressive changes during the period of observation, the glutamic acid falling and glutamine levels rising. Serine and threonine levels were increased significantly above the control values from 30 min after the injection to the end of the experiment. Rectal temperatures (measured with a thermistor probe) after injection of IMA showed a progressive reduction from the control levels throughout the period of observation. An essentially linear correlation was noted between the decreases in body temperature and the differences between the glutamic acid and glutamine values for the first 90 min post‐injection. Our data suggest that IMA affects mechanisms of temperature regulation, possibly in the hypothalamus, and that, among other processes, the activities of glutaminase and of serine and threonine dehydratases in brain might be reduced when brain temperatures fall.
Isolation of hypoxanthine from calf brain
Authors: Mori A. , Ohkusu H. , Kohsaka M. , Kurono M. 
Published: October 2006

Except for the crystalline deposits of hypoxanthine found in skeletal muscle of patients with congenital xanthine oxidase deficiency (xanthinuria) there are few reports concerning oxypurines in the mammalian tissues (Parker, Snedden and Watts, 1969, 1970). Since it is difficult to separate hypoxanthine from xanthine in biological fluids (Simmonds and Wilson, 1967), the distribution of hypoxanthine in mammalian tissues is not known in detail.This paper shows that cubic or rod crystals of C5H4ON4are easily isolated from calf brain by column chromatography with ion exchange resin Amberlite CG120 and their identity with hypoxanthine was shown by means of nuclear magnetic resonance and mass Spectrometry.