bluuebunny/crossref_metadata_2025_split huggingface dataset:
SEQUENCE DIVERSITY STUDIES OF RAT BRAIN RNA: EFFECTS OF ENVIRONMENTAL COMPLEXITY ON RAT BRAIN RNA DIVERSITY
Authors: Grouse Lawrence D. , Schrier Bruce K. , Bennett Edward L. , Rosenzweig Mark R. , Nelson Phillip G. 
Published: October 2006

Abstract—The sequence complexities of rat brain RNAs were measured by RNA‐driven hybridization reactions with nonrepetitive rat DNA. The total sequence complexity of rat brain HnRNA was estimated to be 6.61 x 108 nucleotides while rat brain poly(A)‐mRNA sequence complexity was 1.32 x 108 nucleotides. Up to 33.7% of the total transcribable nonrepetitive DNA was expressed in the nuclear RNA. The nuclear RNAs reacted with complex kinetics over at least 4.5 decades of equivalent Rot (product of RNA concentration and time), with an apparent division into three major RNA abundance classes. The abundances of average nuclear RNA species in these classes ranged from 2.9 x 109 copies per brain (18 copies per cell) to 2.4 x 105 copies per brain (1.5 x 10−3 copies per cell). Poly(A)‐mRNA diversity was sufficient to code for 8.8 x 104 polypeptides of 50,000 daltons. There were also three distinguishable abundance classes of poly(A)‐mRNA with frequencies which ranged from 8.9 x 108 copies per brain (5.5 copies per cell) to 3.2 x 105 copies per brain (2 x 10−3 copies per cell). Evidence for compartmentalization of expressed RNA sequences supports the concept that the extensive morphological and physiological specialization evident in brain parallels extensive transcriptional specialization at the cellular level.Brain and liver RNA diversities were measured under double‐blind experimental conditions in three experiments with rats raised in experientially enriched (EC) or impoverished (IC) environments. Liver RNA diversity of EC animals was not different from that of IC animals. Brain total RNA of EC animals, at equivalent R0ts of 184,000‐212,000, hybridized to 10.6% of rat unique DNA (mean of 11 separate groups of rats). The average hybridization of brain RNA from 11 groups of IC animals in the same range of equivalent Rot was 8.2% of the unique DNA. The difference was statistically significant at P < 0.02. Of 10 groups of 3 littermate pairs (paired across EC and IC groups) brain RNA diversity was greater in EC animals in 8 cases. A least squares fit of the kinetics of hybridization to a pseudo first order reaction showed that, at saturation, the RNA from brains of EC animals was complementary to 16.4% of the unique DNA while that from IC animals was complementary to 9.1%. This difference was found in the least abundant class of rat brain RNA. These changes in sequence diversity reflected either an increase in the number of diverse RNA species present or an increase in the number of copies of certain RNA species in the rats raised in an enriched environment. A change in brain RNA populations of this magnitude may reflect a significant difference in brain function between EC and IC animals.
TRANSPORT OF THREONINE AND TRYPTOPHAN BY RAT BRAIN SLICES: RELATION TO OTHER AMINO ACIDS AT CONCENTRATIONS FOUND IN PLASMA1
Authors: Tews J. K. , Goodand S. S. , Harper A. E. 
Published: October 2006

Abstract—Threonine content of brain decreases in young rats fed a threonine‐limiting, low protein diet containing a supplement of small neutral amino acids (serine, glycine and alanine), which are competitors of threonine transport in other systems (Tewset al., 1977). Threonine transport by brain slices was inhibited more by a complex amino acid mixture resembling plasma from rats fed the small neutral amino acid supplement than by mixtures resembling plasma from control rats or from rats fed a supplement of large neutral amino acids. Greater inhibition was seen with mixtures containing only the small neutral amino acids than with mixtures containing only large neutral amino acids. On an equimolar basis, serine and alanine were the most inhibitory; large neutrals were moderately so; and glycine and lysine were without effect. Threonine transport was also strongly inhibited by α‐amino‐n‐butyric acid and homoserine, less so by α‐aminoisobutyric acid, and not at all by GABA.The complex amino acid mixtures strongly inhibited α‐aminoisobutyric acid transport by brain or liver slices but, in contrast to effects in brain, the extent of the inhibition in liver was not much affected by altering the composition of the mixture.Tryptophan accumulation by brain slices was effectively inhibited by other large neutral amino acids in physiologically occurring concentrations. Threonine, or a mixture of serine, glycine and alanine only slightly inhibited tryptophan uptake; basic amino acids were without effect and histidine stimulated tryptophan transport slightly.These results support the conclusion that a diet‐induced decrease in the concentration in brain of a specific amino acid may be related to increased inhibition of its transport into brain by increases in the concentrations of transport‐related, plasma amino acids.
LABELLING OF BRAIN PROTEINS AT EARLY PERIODS AFTER SUBCUTANEOUS INJECTION OF A MIXTURE OF [U‐14C]GLUCOSE AND [3H]GLUTAMATE
Authors: Gaitonde M. K. , Harms Viki , Evans Gwyneth 
Published: October 2006

Abstract—To obtain evidence of the site of conversion of [U‐14C]glucose into glutamate and related amino acids of the brain, a mixture of [U‐14C]glucose and [3H]glutamate was injected subcutaneously into rats. [3H]Glutamate gave rise to several 3H‐labelled amino acids in rat liver and blood; only 3H‐labelled glutamate, glutamine or γ‐aminobutyrate were found in the brain. The specific radioactivity of [3H]glutamine in the brain was higher than that of [3H]glutamate indicating the entry of [3H]glutamate mainly in the ‘small glutamate compartment’.The 14C‐labelling pattern of amino acids in the brain and liver after injection of [U‐14C]glucose was similar to that previously reported (Gaitondeet al., 1965). The specific radioactivity of [14C]glutamine in the blood and liver after injection of both precursors was greater than that of glutamate between 10 and 60 min after the injection of the precursors. The extent of labelling of alanine and aspartate was greater than that of other amino acids in the blood after injection of [U‐14C]glucose.There was no labelling of brain protein with [3H]glutamate during the 10 min period, but significant label was found at 30 and 60 min. The highest relative incorporation of [14C]glutamate and [14C]aspartate in rat brain protein was observed at 5 min after the injection of [U‐14C]glucose. The results have been discussed in the context of transport of glutamine synthesized in the brain and the site of metabolism of [U‐14C]glucose in the brain.
EFFECTS OF ACUTE HYPERTHERMIA ON POLYRIBOSOMES, IN VIVO PROTEIN SYNTHESIS AND ORNITHINE DECARBOXYLASE ACTIVITY IN THE NEONATAL RAT BRAIN
Authors: Millan Noemi , Murdock Larry L. , Bleier Ruth , Siegel Frank L. 
Published: October 2006

Abstract——Acute hyperthermia produces in situ disaggregation of brain polyribosomes in infant rats, as determined by electron microscopy. Protein synthesis is inhibited in infant, but not weanling, rat brain by 45 min of hyperthermia; this inhibition is reversed during a 2 h recovery period at normothermic conditions. Hepatic protein synthesis was inhibited less than that of brain. Acute hyperthermia also leads to a profound loss of ornithine decarboxylase activity in brain; during recovery the activity of this enzyme overshoots to values greater than those of normothermic control rats. This increase is blocked by cycloheximide administration. In testis, a tissue with high ornithine decarboxylase activity, enzyme activity was not affected by hyperthermia and recovery, indicating tissue specificity for these effects.
NEUROCHEMICAL ABNORMALITY IN I‐CELL DISEASE: CHEMICAL ANALYSIS AND A POSSIBLE IMPORTANCE OF BETA‐GALACTOSIDASE DEFICIENCY1
Authors: Eto Yoshikatsu , Owada Misao , Kitagawa Teruo , Kokubun Yoshiyuki , Rennert OWEN M. 
Published: October 2006

Abstract—Sphingolipid composition in both gray and white matter of a patient with I‐cell disease was normal except for the higher proportion.of GMI‐ganglioside in gray and white matter. In the patient's liver and kidney there was a significant accumulation of ceramide dihexoside and ceramide trihexoside and of sulphatide in kidney. Non‐lipid hexosamine and sialic acid concentration in brain was increased 1.2‐1.5 times above normal. Recovery of myelin from I‐cell's white matter was 80‐100%, suggesting that demyelination, if present, is minimal. Myelin lipid and myelin specific glycoprotein patterns were normal. Except for β‐galactosidase activity the activity of other brain lysosomal enzymes were within the normal range. This finding was similar to that of Hurler's syndrome. Only β‐galactosidase activity was reduced to less than 10% of normal in the patient's brain. To examine the possible metabolic significance of β‐galactosidase deficiency in I‐cell disease the physical characteristics of this enzyme, isolated from tissues from I‐cell, Hurler and control patients, were compared using isoelectric focusing, Con A‐Sepharose and Sephadex G‐150 chromatography. The isoelectric point and the binding affinity of I‐cell β‐galactosidase with Con A‐Sepharose was comparable to normal. However, the isoenzyme patterns of brain and liver I‐cell β‐galactosidase with Sephadex G‐150 gel filtration revealed decreased acid β‐galactosidase. Effects of the addition of sodium chloride on each fraction of β‐galactosidase isoenzymes isolated from I‐cell tissues were markedly different from controls, whereas the pH optimum of these enzymes were similar to normal. These enzyme characteristics in I‐cell tissues were different from normal and Hurler's syndrome. These findings suggest that β‐galactosidase deficiency in I‐cell disease is a more specific phenomenon rather than secondary inhibition as found in the mucopolysaccharidoses and thus may have an important role for the pathogenesis of brain damage and disease occurrence.
THE NATURE OF THE AMINO ACID POOL USED FOR PROTEIN SYNTHESIS IN RAT BRAIN SLICES
Authors: Reith M. E. A. , Schotman P. , van Zwietek B. J. , Gispen W. H. 
Published: October 2006

Abstract—The incorporation into brain slice protein of externally provided [1‐14C]valine was measured at varying levels of valine in the medium, under conditions of constant protein synthesis and equilibration of intracellular valine specific activity. The results indicate that the valine pool used for protein synthesis is not identical to the pool of total free valine. Neither does the incorporation solely occur from an extracellular pool which is in equilibrium with the incubation medium. The data are compatible with a two‐site activation model in which aminoacylation of tRNA occurs at both an internal site utilizing amino acid from the intracellular pool and an external (possibly membranous) site converting extracellular valine directly to valyl‐tRNA. A good fit to the experimental observations is also provided by a compartmented intracellular valine pool model.
PERSISTENCE OF ALTERED RNA SYNTHESIS IN RAT CEREBRAL CORTEX 12h AFTER A SINGLE ELECTROCONVULSIVE SHOCK
Authors: Wynter C. V. A. 
Published: October 2006

Abstract—The effect of electroshock (ECS) on RNA synthesis in nuclei and cytoplasm of rat cerebral cortex was examined using a double label technique by intraventricular injection of [3H] and [14C]orotate. At t h after ECS, the incorporation into nuclear RNA was 80% of the control rate and the appearance of newly synthesized RNA in the cytoplasm was only 27.6%. Analysis on composite polyacrylamide‐agarose gels of purified RNA showed that the 3H/14C ratio of each gel slice slowly increased with decreasing M.W. of the RNA. This has been interpreted as an inhibition in the rate of processing of nuclear RNA. When the nuclear RNA was subjected to denaturation with 50% dimethyl sulphoxide (DMSO) this effect was enhanced. In a similar experiment, rats were injected, treated to ECS and killed 12 h later. The overall incorporation into nuclear and cytoplasmic RNA was increased to 174%, and 137.5% respectively. Analysis on gels showed very little variation in the 3H/14C ratio of the steady state levels of nuclear RNA. They compared well with a control experiment where rats were injected with [3H] and [14C]orotate as described above but no ECS was applied to the [14C] labelled animals. However a 1 h pulse label given 11 h after ECS treatment revealed that the rate of incorporation into nuclear RNA still showed a decrease of 81% of the control. The nuclear RYA fractionated on gels clearly showed that the inhibition of the processing rate of nuclear RNA was still occurring. This effect was again magnified on denaturation of the RNA with DMSO. This suggests that ECS may disturb RNA metabolism in nervous tissue for much longer periods than previously realised.
ACTIVITY AND ISOENZYME PATTERN OF LACTATE DEHYDROGENASE IN ASTROBLASTS CULTURED FROM BRAINS OF NEWBORN MICE
Authors: Nissen Claus , Schousboe Arne 
Published: October 2006

AbstractLactate dehydrogenase activity and isoenzyme distribution was determined in primary cultures of astroblasts as a function of the culture period. The specific activity increased during this period with a peak value (1.91 ± 0.18μmol x min‐1 x mg‐1 cell protein) after 2 weeks in culture. The isoenzyme pattern changed during 3 weeks in culture towards a higher proportion of the H4 (LDH‐1) isoenzyme which is analogous to the in vivo pattern. Omission of serum with or without dBcAMP (0.5 mM) in the culture medium during the third week of culture further enhanced this prominence of the H4 isoenzyme. The specific activity (1.58 × 0.06 μmol x min‐1 x mg‐1 cell protein) of cultures grown in the presence of 0.5 mM‐dBcAMP and absence of serum was close to the activity in the adult brain.
COUPLED TRANSPORT OF GLUTAMATE AND SODIUM IN A CEREBELLAR NERVE CELL LINE
Authors: Stallcup William B. , Bulloch Karen , Baetge E. Edward 
Published: October 2006

AbstractThe cerebellar nerve cell line ε1 has a very effective active transport system for glutamate. Glutamate uptake is dependent on extracellular Na+ and furthermore, 22Na+ uptake is stimulated by glutamate, indicating that glutamate uptake and Na+ uptake are coupled. Two molecules of Na + are transported for each molecule of glutamate. The Km for glutamate is found to be 5 × 10−5M in both the glutamate uptake assay and the 22Na+ uptake assay, providing additional evidence for glutamate‐Na+ coupling. Pre‐incubation with ouabain, which inhibits the Na+‐K+ ATPase, results in a gradual inhibition of glutamate uptake due to the deterioration of the Na+ gradient. Tetrodotoxin, however, has no effect on glutamate‐induced 22Na+ uptake, showing that this Na+ flux does not occur via voltage‐dependent Na+ channels. Studies on the specificity of the ε1 glutamate transport system show that it is distinct from systems that transport alanine and glycine. l‐Glutamate, d‐aspartate, l‐cysteate, and l‐cysteine sulfinate are able to utilize the transport system efficiently. d‐Glutamate, l‐homocysteate, N‐methyl‐d, l‐aspartate, and kainic acid are very poor substrates for the glutamate transport system, and in addition do not stimulate 22Na+ uptake. These data allow us to distinguish the glutamate transport system from the glutamate receptor which is known to mediate depolarization in response to all nine of the above compounds. Thus, ε1 does not have an excitatory glutamate receptor.
RADIOENZYMATIC ASSAY OF FEMTOMOLE CONCENTRATIONS OF DOPA IN TISSUES AND BODY FLUIDS
Authors: Zurcher G. , Prada M. Da 
Published: October 2006

Abstract— A single isotope radioenzymatic procedure for the measurement of DOPA has been developed. The assay combines O‐methylation of DOPA by purified COMT using [3H]SAM as the methyl donor and subsequent purification as the DNFB derivative of 3‐O‐[methyl‐3H]DOPA. The present method is about 100 times more sensitive than currently available DOPA methods. This is due to decreased blank values and increased enzymatic conversion giving transmethylation values of 50% with tissue extracts and values of almost 100% with pure solutions. Although COMT methylates a wide variety of catechol compounds, specificity of the assay is achieved by selective extraction and purification of the final product by tlc.The method has good inter‐assay reliability, the coefficient of variation being about 3.5%.This ultramicromethod was used to determine the steady‐state concentrations of endogenous DOPA in minute samples of brain areas of the rat. In untreated rats brain DOPA levels varied with the mode of death; the highest levels were found in animals killed by microwave irradiation. Unconjugated DOPA was measured in microlitre aliquots of human body fluids.
SUBCELLULAR DISTRIBUTION OF NORADRENALINE IN GUINEA‐PIG CEREBRAL CORTEX AND SPLEEN
Authors: Thomas David Vivian 
Published: October 2006

Abstract— The distribution of noradrenaline (NA) in subcellular fractions of guinea‐pig cerebral cortex and spleen was determined by differential and density gradient centrifugation. Of the primary fractions, the microsomal fraction from both tissues was enriched in NA, that of the spleen having the higher specific activity. Microsomal fractions were therefore placed on gradients and NA determined in the subfractions since these fractions appeared suitable preparations in which to search for discrete populations of vesicles. So that the non‐occluded micro‐particulate bound noradrenaline (MPBNA) content of gradient subfractions could be measured, [3H]NA was used to control for the diffusion and or adsorption of free NA, and occluded lactate dehydrogenase was used to estimate the amount of entrapped MPBNA and soluble NA. Non‐occluded MPBNA on gradients from microsomal fractions of cerebral cortex formed a single peak mainly in subfraction F (0.6‐0.8 m‐sucrose). Spleen microsomal fractions, however yielded two peaks of MPBNA. one in sub‐fractions D to G (0.4‐1.0 m‐sucrose) and the other in sub‐fraction J (1.4 m‐sucrosc); electron microscopy showed that the latter subfraction contained large vesicles.Since there were unexpectedly small amounts of MPBNA in microsomal subfractions D and E of cerebral cortex, the synaptosome fraction was investigated. Following water treatment of synaptosomes. MPBNA formed a peak in subfraction E (0.4‐0.6 m‐sucrose) with smaller amounts in subfractions D and F (0.4 and 0.6 0.8 m‐sucrose).
BIOLOGICAL ACTIVITY OF THE β NERVE GROWTH FACTOR: THE EFFECTS OF VARIOUS ADDED PROTEINS
Authors: Stach Robert W. , Garian Nora , Olender Edward J. 
Published: October 2006

Abstract—The biological activity of β nerve growth factor varies greatly when other proteins are added to the culture medium. We have found that the biological activity can vary by a factor of 7 in a bioassay using 9 day embryonic chick sensory ganglia by adding bovine serum albumin to the culture medium. Adding the α and γ subunits in the form of 7S nerve growth factor has no effect on the biological activity of the β nerve growth factor. On the other hand, cytochrome c has an intermediate effect. Most of the increase in the biological activity seen on the addition of other proteins seems to be due to the ability of the other proteins to keep β nerve growth factor in solution; i.e. to prevent its adsorption to the culture tubes. However, some of the increase may also be due to an interaction that causes an activation of the β nerve growth factor.
Thymidine Phosphorylase Activity in the Optic Tectum of Developing Chick Embryos and the Effects of 3′,5′‐Cyclic Nucleotides and Monosodium Glutamate on Enzyme Activity
Authors: Hyndman A. G. 
Published: October 2006

Abstract:Changes in activities of thymidine phosphorylase (EC 2.4.2.4.) in the optic tectum of developing chick embryos were determined and the effects of the addition of adenosine 3′,5′‐monophosphate or guanosine 3′,5′‐ monophosphate to the test medium were also determined. In addition, injection of 30 mg of monosodium glutamate onto the chorioallantoic membrane was assessed for effect on thymidine phosphorylase activity in the optic tectum. Thymidine phosphorylase activity was highest at the earliest times studied, peaking at the 10th day of incubation, but decreasing sharply until the 12th day, at which time a new level of activity was maintained until after the 18th day. Between the 18th day and 1 day post‐hatching there was a steady decrease in activity. The addition of adenosine 3′,5′‐monophosphate (cAMP) to the test medium resulted in decreased enzyme activity at 10 and 16 days of incubation, but no change at 1 day post‐hatching; guanosine 3′,5′‐monophosphate (cGMP) in the test medium resulted in decreased activity at 16 days, but in no change at 10 days or 1 day post‐hatching. The injection of monosodium glutamate into the egg before 10 days of incubation resulted in a decrease in enzyme activity only at 10, 18, and 20 days of incubation. Thymidine phosphorylase activity during optic tectum development has two phases (days 8‐10 and days 12‐18), each followed by a decrease in enzyme activity. The addition of cAMP to the test medium lowers activity during both phases, and cGMP only affects the second phase. This suggests two mechanisms for control of the enzyme, one present during both phases and one only during the second phase. That a single injection of MSG decreases enzyme activity at 10, 18, and 20 days of incubation, but not days 12‐16 or 1 day post‐hatching, suggests that MSG has not only immediate but also long‐term biochemical effects on prenatal brain development.
Differences Between Intracellular Platelet and Brain Proteins that Bind Serotonin
Authors: Tamir H. , Bebirian R. , Muller F. , Casper D. 
Published: October 2006

Abstract:Two proteins with binding capacity highly specific for serotonin are present in the 100,000 g supernatant obtained from rat platelets: a glycoprotein and albumin. They were purified by means of (NH4)2SO4 fractionation, Sephadex sieve chromatography, and affinity column chromatography. The two proteins differed in most of their physical and chemical properties: (a) migration on 7.5% acrylamide gel of the complex (protein‐Fe+2‐[3H]serotonin); (b) molecular weight (sodium dodecyl sulfate gels); (c) carbohydrate reaction; (d) binding capacity and binding constants; (e) effect of reserpine; (f) heat stability; and (g) isoelectric point. However, they showed two similar properties: sensitivity to trypsin and dependence on Fe +2 for serotonin binding. The properties of both the glycoprotein and albumin differ considerably from those of serotonin binding protein of brain (SBP), which was not detected in platelets. Since brain serotonin binding protein is thought to be involved in storage of the amine, these results suggest that the storage form of serotonin in rat platelets is different from that in rat brain. These results also imply that the storage of serotonin in platelets may not serve as a model for the storage of serotonin in nerve terminals of the brain.