bluuebunny/crossref_metadata_2025 huggingface dataset:
METABOLISM OF GLUCOSE, AMINO ACIDS, AND SOME RELATED METABOLITES IN THE BRAIN OF TOADS (BUFO BOREAS) ADAPTED TO FRESH WATER OR HYPEROSMOTIC ENVIRONMENTS
Authors: Shank R. P. , Baxter C. F.
Published: October 2006

The levels and specific radioactivities (SA) of glucose, lactate, pyruvate, α‐oxoglutarate and seven amino acids in the brain of toads adapted to fresh water or to an hyperosmotic environment were analysed at various times (5 min–4 h) after an injection of [U‐14C]glucose into the bloodstream. The concentrations and SA of glucose, lactate and five amino acids in blood plasma also were measured. In addition, the SA of glutamine, glutamate, aspartate and GABA in brain were determined 30 min after an injection of [1,5‐14C]citrate into the cisterna magna.

The flow of labelled carbon atoms from glucose to amino acids and related metabolites in the toad brain was qualitatively similar to that in the mammalian brain, but quantitatively less than one‐tenth of the rate in the brain of rats. Hyperosmotic adaptation induced a large increase in the levels of glucose and amino acids in the brain without affecting the rate of glucose utilization. The SA of several amino acids relative to the SA of glucose were initially lower in hyperosmotically‐adapted toads than in toads adapted to fresh water, presumably because of a greater dilution of isotope by the larger amino acid pools in the hyperosmotically‐adapted toads. The rates of synthesis of alanine and glutamine from pyruvate and glutamate, respectively, appeared to increase with hyperosmotic adaptation, but the rate of GABA synthesis from glutamate was unaltered. The SA of α‐oxoglutarate and glutamate were similar at all time periods in both groups of toads, an indication that these compounds were interconverted much more rapidly than the rate at which α‐oxoglutarate was formed from isocitrate.

The SA of lactate in comparison to that of glucose varied but was always considerably lower, even at 4 h after the [14C]glucose injection. After[U‐14C]glucose, glutamine had a SA lower than that of glutamate, whereas after the injection of [14C]citrate, glutamine was formed with a SA much higher than that of glutamate. Hence, glutamate in the toad brain exhibited metabolic compartmentation similar to that in rat brain.
TRANSPORT OF CHOLINE ACETYLTRANSFERASE AND ACETYLCHOLINESTERASE IN THE RAT SCIATIC NERVE: A BIOCHEMICAL AND ELECTRON HISTOCHEMICAL STUDY
Authors: Kéasa P. , Mann S. P. , Karcsu Sarolta , Tóth L. , Jordan Susan
Published: October 2006

The transport of acetylcholinesterase (AChE) and choline acetyltransferase (ChAc) were investigated by biochemical and histochemical methods. After ligature of one of the sciatic nerves of the rat for varying times—4, 14, 20 and 44 h—the normal levels and the accumulation of AChE and ChAc activities were investigated. It can be inferred from the results that there is a rapid accumulation of AChE activity just proximal to the ligature, while the increase in ChAc activity is less pronounced. Distal to the ligature the level of AChE is above the control value whereas, in contrast to this, the ChAc activity is significantly decreased. Histochemical demonstration of the two enzymes indicates that they are present in the cholinergic axons. The reaction end‐product produced by AChE occurs within vesicles and neurotubules, while the endproduct due to ChAc appears to be free in the axoplasm, bound to neurofilaments and on the outer surface of vesicles and tubules.
ANALYSIS OF THE MAJOR AMINO ACIDS OF RAT BRAIN AFTER IN VIVO INHIBITION OF GABA TRANSAMINASE BY ETHANOLAMINE O‐SULPHATE
Authors: Fowler L. J.
Published: October 2006

The effect of in vivo inhibition of GABA transaminase by ethanolamine O‐sulphate on the content of the free amino acids in rat brain has been studied. Intracisternal injection of 2.0 mg/kg resulted in a progressive increase in GABA levels with time, to reach after 8 h a 100 per cent increase over saline‐injected control animals. The effect of injection of 0.5, 1.0 and 2.0 mg/kg was studied 24 h after injection and the results showed that the increased GABA levels were dependent on the dose of inhibitor employed. Apart from the substantial increase in the GABA concentration of the brain there were no significant changes in the content of the other amino acids except for a small but significant decrease in aspartic acid in one experiment. When the extent of inhibition of the transaminase was correlated with the rise in GABA concentration it was shown that no elevation occurred until more than half of the enzymic activity had been inhibited.
HISTAMINE‐DEPENDENT FORMATION OF N‐ACETYL‐ASPARTYL PEPTIDES IN MOUSE BRAIN
Authors: Reichelt K. L. , Kvamme E.
Published: October 2006

Abstract— The formation of N‐acetyl‐aspartyl‐peptides in mouse brain homogenates is described. The formation is completely dependent on histamine and on an ATP‐regenerating system, and partially dependent on the addition of N‐acetyl‐aspartate and certain other amino acids. The N‐acetyl‐aspartyl‐peptide formation is probably non‐ribosomal and is apparently not due to hydrolysis of preformed proteins.
LIPID AND PROTEIN CHANGES IN SCIATIC NERVE DURING WALLERIAN DEGENERATION
Authors: Wood J. G. , Dawson R. M. C.
Published: October 2006

Lipid and protein changes have been measured and correlated during early Wallerian degeneration in the same rat sciatic nerve. The major structural glycoprotein disappears at a steady rate and little remains after 8 days. There is a concomitant appearance of a protein with the same molecular size as basic protein B2 and which is probably formed from the glycoprotein. Basic protein (B1) is slowly lost, but Wolfgram protein tends to increase possibly because of glial cell proliferation. Cholesterol ester has appeared 3 days after sectioning, while cholesterol and probably cerebroside are reduced. Triglyceride levels show considerable variation, but biphasic increases tended to occur at 3‐4 and 10‐14 days. Loss of phospholipids is a later event. The changes in lipid and protein are discussed in relation to the stability of the peripheral nerve myelin membrane.
INTRASYNAPTOSOMAL CONVERSION OF TYROSINE TO DOPAMINE AS AN INDEX OF BRAIN CATECHOLAMINE BIOSYNTHETIC CAPACITY1
Authors: Kuczenski R. , Segal D. S.
Published: October 2006

—The potential for intrasynaptosomal conversion of tyrosine to dopamine was evaluated in the cell bodies (substantia nigra) and nerve terminals (caudate‐putamen) of the nigral‐striatal dopaminergic pathway. The conversion technique involves measurement of 14CO2 evolved from carboxyl‐labelled tyrosine in the absence of both exogenous pteridine cofactor and DOPA decarboxylase. Evaluation of apparent Km values for tyrosine uptake and conversion and observed maximal velocities suggest that conversion is not limited by movement of substrate into the synaptosomes. The results, based on brain regional and subcellular distribution, are consistent with the localization of conversion in nerve endings and suggest a rapid and reliable measure for catecholamine biosynthetic capacity when structural integrity of the nerve ending is maintained.
BIOCHEMICAL STUDIES ON DEGENERATIVE NEUROLOGICAL DISORDERS: 1. ACUTE EXPERIMENTAL ENCEPHALITIS
Authors: Bowen D. M. , Flack R. H. A. , Martin R. O. , Smith Carolyn B. , White Pamela , Davison A. N.
Published: October 2006

—Weanling mice were either injected with viruses or fed cuprizone. Changes in total activity of two cathepsins and two β‐glycosidases were characteristic of each of the five acute encephalopathies studied. Comparisons made between morphological change and hydrolase activity shows that β‐galactosidase and cathepsin A may be useful indices of neuronal degeneration and cellular infiltration into white matter, respectively. β‐Glucuronidase appears to be a particularly sensitive index of cellular reactions to injury. Cathepsin D activity does not appear to reflect any one type of neural cell. Although the morphological changes included neuronal degeneration, perivascular cuffing with mononuclear cells, astrocytic hypertrophy and microgliosis none of the experimental conditions mimicked biochemical changes in multiple sclerosis or senile dementia. The measurement of lysosomal enzymes appears to be a more sensitive indication of acute neurological disorder than the screening of brain proteins by polyacrylamide gel clectrophoresisor the measurement of enzymes (acetylcholinesterase, DOPA decarboxylase and carbonic anhydrase) characteristic of neural cells.
DIFFERENT RECOVERY RATES OF THE ELECTROPHYSIOLOGICAL, BIOCHEMICAL AND MORPHOLOGICAL PARAMETERS IN THE CHOLINERGIC SYNAPSES OF THE TORPEDO ELECTRIC ORGAN AFTER STIMULATION
Authors: Zimmermann H. , Whittaker V. P.
Published: October 2006

—During stimulation there occurred a decay in electrical response, vesicular acetylcholine, ATP and nucleotide as well as a loss of vesicle number and a decrease in vesicle diameter in the electric organ of Torpedo. These alterations were re‐established during a subsequent recovery period. The different parameters recovered at different rates. Firstly, electrical response to single pulses recovered to prestimulation values within about 5 h. Vesicle number and diameter as well as bouton size were found to be re‐established fully after 24 h. The newly formed vesicles appeared to be empty as vesicular acetylcholine, ATP and total nucleotide recovered much more slowly and were back to control values after about three days. Acetylcholine reappeared more quickly in the vesicles than ATP. Only after recovery of the vesicular pool of transmitter and ATP did the electric organ regain full stability of the electric discharge pattern on restimulation.
EFFECT OF ACTINOMYCIN‐D ON LABELLED MATERIAL IN THE RETINA AND OPTIC TECTUM OF GOLDFISH AFTER INTRAOCULAR INJECTION OF TRITIATED RNA PRECURSORS
Authors: Ingoglia N. A. , Grafstein Bernice , McEwen B. S.
Published: October 2006

—After injection of [3H]guanosine or [3H]uridine into the eye of goldfish, labelled acid‐soluble radioactivity and RNA appeared in the contralateral optic tectum. When 0·1 μg actinomycin‐D was injected into the eye 4 h before the precursor, the labelled RNA in the retina by 18 h after the injection was only 23 per cent of normal, but the acid‐soluble radioactivity in the retina and the small amount of labelled acid‐soluble material conveyed to the tectum were not significantly affected; by 15–20 days after the injection the acid‐soluble radioactivity in the retina was reduced and the amount of labelled material conveyed to the tectum, including both RNA and acid‐soluble fractions, was less than normal.

When the actinomycin was injected at various times before or after the precursor and measurements were made 6 days later, it was found that the amount of labelled RNA conveyed to the tectum was maximally decreased if the inhibitor was given simultaneously with or up to 4 h before the precursor, whereas the amount of RNA was normal if the incorporation of the precursor had been allowed to proceed for 12 h before the inhibitor was given. This result would be consistent with the view that much of the RNA conveyed to the tectum had been synthesized in the retina within 12 h of the injection of the precursor, and had then presumably been axonally transported in the optic nerve to the tectum. However, since the acid‐soluble material conveyed to the tectum was also reduced as a result of the actinomycin treatment, the results of these experiments with actinomycin do not unequivocally rule out the possibility that the RNA appearing in the tectum had been locally synthesized from the axonally transported acid‐soluble material. In the retina, both the labelled RNA and acid‐soluble fractions were reduced, to about 15 and 60 per cent of normal, respectively, without any relationship to the time between the injection of inhibitor and precursor. The discrepancy between the effects of the labelling of the retina and the labelling of material conveyed to the tectum could be correlated with the fact that the actinomycin caused severe damage to the retinal receptor cells, while leaving the ganglion cells relatively intact. The more pronounced effect of actinomycin on the receptor cells could in turn be correlated with the fact that these cells had a higher rate of RNA synthesis than the ganglion cells. This was demonstrated autoradiographically by the higher rate of incorporation of [3H]uridine into the receptor cells.

Intracranial injection of actinomycin did not affect significantly the amount of labelled RNA conveyed to the tectum, which would argue against the local synthesis of this RNA. It is not certain, however, that the actinomycin penetrated deeply enough into the tectum to be effective.
FREE AMINO ACID LEVELS IN THE CEREBROSPINAL FLUID OF NORMAL HUMANS AND THEIR VARIATION IN CASES OF EPILEPSY AND SPIELMEYER‐VOGT‐BATTEN DISEASE
Authors: Plum C. M.
Published: October 2006

Abstract— The concentrations of free amino acids in the plasma and cerebrospinal fluid from control subjects and from patients suffering from epilepsy and Spielmeyer‐Vogt‐Batten disease were determined using an automatic amino acid analyser. It was found that the plasma/cerebrospinal fluid ratio of amino acid concentrations showed the variation in the amounts of free amino acids in epilepsy more clearly than the cerebrospinal fluid levels alone.
SEROTONIN AND FREE AMINO ACID ANALYSIS OF GANGLIA AND ISOLATED NEURONES OF APLYSIA DACTYLOMELA
Authors: Cottrell G. A.
Published: October 2006

—The presence of serotonin and different amino acids was investigated in the ganglia and in isolated giant neurones of Aplysia dactylomela. With a few exceptions the pattern of substances was similar in all the ganglia. Of the many identified neurones studied only one giant neurone located in each cerebral ganglion was found to contain serotonin. GABA was detected in most extracts, including those of the serotonin‐containing neurone, known cholinergic, and known neurosecretory neurones. Putrescine, recently detected in extracts of nervous tissue and isolated neurones of Helix, was not detected in Aplysia nervous tissue.
LOCAL CHANGES IN SUBCELLULAR DISTRIBUTION OF DOPAMINE‐β‐HYDROXYLASE (EC 1.14.2.1) AFTER BLOCKADE OF AXONAL TRANSPORT
Authors: Brimijoin S.
Published: October 2006

Abstract— The distribution of DBH activity between soluble and sedimentable fractions of hypotonic homogenates was examined in rat sympathetic ganglia and nerves after interruption of axonal transport. Local application of colchicine to superior cervical ganglia caused an increase mainly in particulate DBH activity, which was presumably bound to membranes. Likewise, in sciatic nerves, particulate DBH activity accumulated on both sides of a ligature and disappeared from a region well below a ligature much faster than did soluble activity. On the other hand, 18 h after simultaneous application of two ligatures to the nerve, neither total DBH activity nor subcellular distribution of this activity changed in the isolated nerve region. More detailed analysis showed that ligation affected the distribution of DBH activity within a fraction that sedimented at 140,000 g after homogenization of nerves in isotonic sucrose. Just above a ligature, osmotically releasable DBH activity was a smaller proportion of the sedimentable activity than in control nerves. However, as compared to controls, osmotically releasable DBH activity was a larger proportion of the activity in the sedimentable fraction from a region well below a ligature. A model was developed which accounts for some of these results by postulating that DBH is associated with different compartments in sciatic nerve which have different rates of transport and different proportions of soluble and bound enzyme.
DISTRIBUTION OF ACETYLCHOLINE, CHOLINE, CHOLINE ACETYLTRANSFERASE AND ACETYLCHOLINESTERASE IN REGIONS AND SINGLE IDENTIFIED AXONS OF THE LOBSTER NERVOUS SYSTEM
Authors: Hildebrand J. G. , Townsel J. G. , Kravitz E. A.
Published: October 2006

Abstract— Acetylcholine, its precursor (choline), and the enzymes of its biosynthesis and degradation (choline acetyltransferase and acetylcholinesterase, respectively) have been studied and quantified in extracts of several regions of the nervous system of the lobster and in single, isolated axons of identified efferent excitatory, efferent inhibitory and afferent sensory neurons. The choline acetyltransferase is a soluble enzyme similar to that from other species. The predominant acetylcholine‐hydrolysing enzyme is largely membrane‐bound and has been characterized as a specific acetylcholinesterase. A single peak of acetylcholinesterase activity can be detected upon velocity sedimentation analysis of Triton X‐100‐treated extracts of all regions of the nervous system. Choline acetyltransferase distribution parallels that of sensory neural elements, and its specific activity shows nearly a 500‐fold difference from the richest to the poorest neural source. Acetylcholinesterase levels span only a 23‐fold range, and activity is found in all neural regions, including those free of known sensory components. A radiochemical microassay for choline and acetylcholine in the range of 20–2000 pmol is described in detail. All 3 types of axons contain comparable levels of choline (ca. 2 pmol/μg protein), but acetylcholine is asymmetrically distributed. Efferent axons contain no detectable acetylcholine, while sensory axons from abdominal muscle receptor organs have an average of 1·9 pmol/μg protein. Choline acetyltransferase is similarly distributed; sensory axons show at least 500‐fold greater activity than efferent axons. Acetylcholinesterase is nearly uniformly distributed among the three types of fibres. These results are discussed in terms of a general view of transmitter accumulation in single neurons.
SODIUM‐DEPENDENT EFFLUX AND EXCHANGE OF GABA IN SYNAPTOSOMES
Authors: Simon J. R. , Martin D. L. , Kroll M.
Published: October 2006

Abstract— The influx and efflux of [3H]GABA were investigated in synaptosomes. Two efflux components were detected. The first, termed spontaneous efflux, was not affected by the external sodium chloride concentration. The second, termed GABA‐stimulated efflux, was observed when low levels of GABA were added to the incubation medium and was found to require external sodium chloride. The rate of spontaneous efflux at 0°C was about 37 per cent of the rate at 27°C but both GABA‐stimulated efflux and GABA influx were completely inhibited at 0°C. The stimulation of efflux by external GABA followed simple Michaelis–Menten kinetics with respect to external GABA. The concentration of external GABA required for half‐maximal stimulation was 4·9 ± 1·4 μm and the Vmax for efflux was 1·0 ± 0·6 nmol. min‐1.mg‐1 of protein. A similar stimulation of efflux was observed with GABA analogue l‐2,4‐diamino‐butyric acid which is a competitive inhibitor of influx. The concentration of external l‐2,4‐diaminobutyric acid required for half‐maximal stimulation of efflux was 51 ± 12 μm and the Vmax for efflux was 0·8 ± 0·5 nmol.min‐1.mg‐1 of protein. Since the sodium‐dependency, temperature sensitivity, and kinetic properties of the GABA‐stimulated efflux system were similar to the influx system, GABA‐stimulated efflux was attributed to carrier‐mediated exchange diffusion. Measurement of efflux and influx in the same preparation showed there was a net efflux when total fluxes were considered and that the exchange ratio (influx to GABA‐stimulated efflux) was 0·9 when carrier‐mediated fluxes were considered. The effect of the temperature of the fluid used to rinse synaptosomes collected on filters in influx experiments was investigated. There was no detectable difference in measured values of influx between samples rinsed with cold fluid (0°C) and warm fluid (27°C). The endogenous GABA content of synaptosomes was found to be 20·3 ± 2·5 nmol GABA per mg of protein. From this value, the cytoplasmic concentration of GABA in synaptosomes was estimated to be a maximum of 40 mm. About 5 per cent of total cerebral cortical GABA was found in the synaptosomal fraction.
SCORPION TOXIN‐INDUCED CATECHOLAMINE RELEASE FROM SYNAPTOSOMES
Authors: Moss J. , Colburn R. W. , Kopin I. J.
Published: October 2006

Abstract— A toxin purified from crude venom of the scorpion L. quinquestriatus releases [3H]norepinephrine from synaptosomes prepared from rat brain. The toxin‐induced release is dependent on duration of exposure and concentration of toxin in the medium. The absence of calcium in the medium diminishes toxin‐induced release but does not abolish it. Toxin‐induced release is diminished by tetrodotoxin or, to a lesser extent, by desmethylimipramine. Since the released tritium is present predominantly as norepinephrine, it appears that toxin‐induced release is similar to that produced by veratradine or tyramine and is distinct from reserpine induced release.
ANOMALIES OF MYELIN‐ASSOCIATED GLYCOPROTEINS IN‘QUAKING MICE
Authors: Matthieu Jean‐Marie , Brady R. O. , Quarles R. H.
Published: October 2006

Abstract— Proteins and glycoproteins in a myelin fraction isolated from Quaking mutant mice were separated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate and stained with Fast Green or with periodic acid‐Schiff reagents. Double labelling experiments with [3H]fucose and [14C]fucose were also used to compare glycoproteins in myelin from the mutant mice with those from control mice. In the myelin fraction from the Quaking mice the basic proteins and proteolipid protein were decreased relative to the high molecular weight proteins. Some glycoproteins which are present in small amounts in myelin from normal mice were increased relative to the major glycoprotein in the myelin fraction of the Quaking mice. Furthermore, the major myelin‐associated glycoprotein was shifted toward higher apparent molecular weight in comparison with controls of the same age or even with 9‐day‐old controls. The abnormal glycoproteins in the mutant myelin fraction could be a factor in the impairment of myelination.
UPTAKE AND METABOLISM OF GLUTAMATE BY ISOLATED TOAD BRAINS CONTAINING DIFFERENT LEVELS OF ENDOGENOUS AMINO ACIDS
Authors: Shank R. P. , Baxter C. F.
Published: October 2006

—The uptake of [U‐14C]glutamate into the amphibian brain was studied in vitro using brains from toads (Bufo boreas) adapted either to a fresh water (FWA) or an hyperosmotic saline (HOA) environment. Initial rates of 14C‐glutamate uptake showed a single apparent Km of about 0·2 mm. Uptake by HOA brains was slower than that by FWA brains, reflecting perhaps a non‐competitive type of inhibition by the higher content of glutamate in the HOA brains. Although the glutamate content of HOA brains was maintained during prolonged incubation at twice the level found in FWA toads, other metabolic parameters measured in the two types of brain preparations were surprisingly similar. Tissue to medium concentration ratios of greater than 3000:1 were generated by both FWA and HOA brains. In both brain systems the clearance of glutamate from the medium was accompanied by a rapid conversion of the amino acid to glutamine and its release into the medium. In both the FWA and HOA toad brain systems some [U‐14C]glutamate was metabolized to aspartate and GABA; in both systems the specific radioactivity (SA) of glutamine in the tissue was from two to four times greater than that of glutamate; also the SA of glutamine released into the medium was higher by several orders of magnitude than the SA of glutamine in brain tissues.

These and other findings support the concept that, in both the FWA and HOA toad brains, transport processes are instrumental in preserving low extracellular levels of glutamate but that mechanisms other than transport are responsible for the maintenance of different levels of glutamate in the FWA and HOA toad brains.
INHIBITION OF AMINO ACID UPTAKE BY THE ABSENCE OF Na+ IN SLICES OF BRAIN
Authors: Lajtha A. , Sershen H.
Published: October 2006

—The Na+ requirement of amino acid transport was measured in brain slices. The tissue was first washed free of Na+ and then Na+ was replaced by one of the following: choline, Li+, Rb+, or mannose. Amino acid uptake was measured at different times (5–120 min) and at low (10‐7–10‐5m) and high (10‐3m) concentrations. Most of the Na+ could be washed out of the tissue; this also decreased K+ levels despite increased K+ in the medium. K+ tissue levels were partially restored when Na+ was added.

The absence of Na+ abolished the uptake of Glu, Asp, GABA, Gly, Tau and Pro. Most of the neutral amino acids (Ala, Val, Trp, His) were very strongly inhibited by the absence of Na+ under most experimental conditions. Basic amino acids (Arg, Lys) were not completely inhibited, in that 30 per cent of the equilibrium uptake remained and some of the basic amino acid influx was independent of the Na+ tissue level. The uptake of amines (tyramine, cadaverine, putrescine) did not require Na+, and often was greater in the absence of Na+.

We conclude that amino acid uptake in brain slices is Na+ dependent, although the absence of Na+ may affect transport indirectly.
ACCUMULATION OF TRIENOIC FATTY ACIDS IN RAT BRAIN AFTER DEPLETION OF LIVER (n‐6) POLYUNSATURATED FATTY ACIDS
Authors: Galli C. , Agradi E. , Paoletti R.
Published: October 2006

Abstract— The relative rates of accumulation (mg/g fresh weight) of (n‐6)tetraenoic and (n‐9)trienoic fatty acids in brain and liver of developing rats during essential fatty acid deficiency, show that accumulation of (n‐6) acids in brain occurs concomitantly with depletion of the liver stores of polyunsaturated acids, and indicate that considerable accumulation of trienes occurs in the brain, reaching levels (mg/g) even higher than those present in the liver, only after depletion of tetraenes in the liver. The brain thus incorporates very actively long chain polyunsaturated fatty acids both of the (n‐6), and of the (n‐9) series, when (n‐6) compounds are not available any longer.
FRACTIONATION OF RNA FROM BRAIN SYNAPTOSOMES AND CYTOPLASMIC SUBCELLULAR FRACTIONS
Authors: Cupello A. , Hydén H.
Published: October 2006

—RNA from rat brain synaptosomes, mitochondria and microsomes was analysed by gel electrophoresis under conditions allowing good resolution in three different molecular weight ranges: 4s‐16s, 16s‐28s and >28s.

Two synaptosome specific RNA bands were found, one with comparatively low molecular weight (8‐9 × 104 Daltons) and another very large (sE > 60s).

RNA species with electrophoretic characteristics similar to those reported for liver mitochondrial RNA were found in brain mitochondria. From the electrophoretic data their mean geometric radii were determined.
AN IMPROVED METHOD FOR THE MEASUREMENT OF 14CO2 APPLIED TO A PROBLEM OF CYSTEINE METABOLISM IN SQUID NERVE
Authors: Hoskin F. C. G. , Pollock M. L. , Prusch R. D.
Published: October 2006

—A method has been developed for the measurement of metabolically evolved 14CO2 which reduces contamination, utilizes conventional scintillation counting equipment, and makes possible direct comparisons with liquid samples without the need for large correction factors. The application of the method reveals that cysteine is transported into squid axons where much of it is decarboxylated, but where very little of the remainder of the molecule is metabolized to CO2. In contrast, pyruvate is taken up much more slowly, probably by diffusion, but is almost entirely metabolized to CO2. Thus cysteine does not appear to be appreciably metabolized by squid nerve via a ‘pyruvate pathway’. Although only a little appears to be metabolized via a ‘taurine pathway’, that small portion goes mainly to hypotaurine, and none goes beyond to isethionate.
THE INTRINSIC FLUORESCENCE CHARACTERISTICS OF THE MYELIN BASIC PROTEIN
Authors: Jones A. J. S. , Rumsby M. G.
Published: October 2006

—The encephalitogenic basic protein has been isolated from the myelin sheath of ox brain white matter and the purity and amino acid composition have been verified. The intrinsic fluorescence characteristics of the purified basic protein have been determined and the results interpreted in terms of current ideas on the structure of the protein. Fluorescence data obtained from the basic protein in aqueous solution indicate that the tyrosine and tryptophan residues are largely exposed to the solvent and that resonance energy transfer from tyrosine to tryptophan is very inefficient. Denaturing conditions in 8 m‐urea have little effect on the fluorescence properties of the protein. The ionic detergent, sodium dodecyl sulphate, interacts with the basic protein and alters the fluorescence properties in a manner which indicates that the tryptophan residue is in the hydrocarbon chain region of the detergent while the local positive charge around the tyrosine residues is neutralized by the negatively charged sulphate head‐groups. The fluorescence results suggest that the basic protein can be used as a natural, non‐perturbing probe which will report on its environment after it has reacted with other membrane components.
EFFECTS OF AMINO‐OXYACETIC ACID, ETHANOLAMINE‐O‐SULPHATE AND GABA ON THE CONTENTS OF GABA AND VARIOUS AMINES IN BRAIN SLICES
Authors: Starr M. S. , Tanner T.
Published: October 2006

—The effects of amino‐oxyacetic acid, ethanolamine‐O‐sulphate and γ‐aminobutyric acid (GABA) on the contents of GABA, noradrenaline, dopamine and serotonin (5‐HT) in slices of rat hypothalamus and midbrain were studied in vitro using a simultaneous fluorimetric assay procedure. Following control incubations the levels of 5‐HT were raised, while the levels of the other substances remained steady. Amino‐oxyacetic acid caused a reduction in the contents of noradrenaline and 5‐HT, but had no effect on either GABA or dopamine. Ethanolamine‐O‐sulphate both raised the GABA content and lowered the noradrenaline content of slices, while the levels of dopamine and 5‐HT were not altered. The presence of GABA in the incubation medium produced complex changes in these levels, depending both on the dose of GABA used and the brain area studied. In the hypothalamus, 0·07 mm‐GABA caused an elevation in 5‐HT, a drop in noradrenaline, and no change in either GABA or dopamine. With 5 mm‐GABA, the noradrenaline level was raised slightly above control values and the endogenous GABA level doubled, while 5‐HT and dopamine levels were not different from controls. Similar changes in 5‐HT and GABA contents were observed with midbrain slices, but noradrenaline and dopamine were not affected. The possible modes of action of amino‐oxyacetic acid and ethanolamine‐O‐sulphate on the amino acid and amine systems in the brain are discussed.
PARTIAL CHARACTERIZATION OF BASIC PROTEINS OF CHICKEN, TURTLE AND FROG CENTRAL NERVOUS SYSTEM MYELIN
Authors: Martenson R. E. , Deibler Gladys E.
Published: October 2006

Abstract—

Myelin basic proteins were isolated from CNS tissues of chicken, turtle and frog and compared with the corresponding protein of bovine origin. At acid pH all four proteins had comparable mobilities in polyacrylamide gels. Upon electrophoresis at alkaline pH the submammalian proteins, like the bovine protein, were separated into multiple components. The components of the chicken and frog proteins had exceptionally high and low mobilities, respectively, while those of the turtle protein had mobilities comparable to those of the bovine protein. The chicken and turtle proteins were similar to the bovine protein in amino acid composition except for containing considerably more serine and valine and having higher proportions of histidine to lysine. The frog protein differed further in having an unusually high content of tyrosine (approx 9 mol/mol protein), an unusually high arginine: glycine ratio (1.09) and practically no methylated arginine (0‐0.036 mol/mol protein). Like those of mammalian origin, the submammalian proteins each contained a single tryptophan and two methionines. Arginine, serine and glycine together accounted for approximately 40 per cent of the residues in each protein. The chicken and turfle proteins each contained roughly equal amounts of NG‐monomethyl‐ and NG, NG‐dimethylarginine, the two derivatives together comprising 0.5‐0.6 mol/mol protein. No NG, NG‐dimethylarginine was detected in any of the proteins examined. The microheterogeneity observed in the chicken and turtle proteins upon electrophoresis at alkaline pH was reproduced upon alkaline pH chromatography on carboxymethylcellulose. Chromatographic fractions of the chicken protein which differed electrophoretically at alkaline pH had virtualy identical amino acid compositions and apparent molecular weights and all contained comparable amounts of both NG‐monomethyl‐ and NG, NG‐dimethylarginine. Treatment of the submammalian proteins with BNPS‐skatole yielded two fragments comparable in size, charge and staining characteristics to those similarly produced from the bovine protein (residues 1‐116 and 117‐170). Fragments produced from the frog protein by treatment with BrCN were comparable in size and charge to those similarly produced from the bovine protein; those produced from the chicken and turtle proteins were much different. In immunodiffusion studies the submammalian and bovine proteins showed reactions of identity when tested against rabbit anti‐chicken basic protein serum.
AMINO ACID TRANSPORT IN PERIPHERAL NERVE: SPECIFICITY OF UPTAKE
Authors: Wheeler D. D.
Published: October 2006

Abstract—

Amino acid uptake has been studied in desheathed frog sciatic nerve. Results indicate that at least two types of processes are involved: a non‐saturable process, possibly simple diffusion, and a saturable, carrier‐mediated process. There appear to be several carrier‐mediated transport mechanisms, which can be separated on the basis of their substrate specificity as follows: small neutral, large neutral, β‐alanine, acidic, basic, aromatic and heterocyclic, and proline. The specificity of some of the mechanisms is incomplete and these can transport certain amino acids from other groups to a limited extent. The percentage of total uptake by a saturable process is highly variable. Basic, acidic, and those amino acids containing aromatic or heterocyclic ring structures are taken up primarily by a saturable process; small and large neutral amino acids and proline are taken up primarily by a non‐saturable process.
POSSIBLE DEFECT IN CHOLINERGIC NEURONS OF MUSCULAR DYSTROPHIC MICE1
Authors: Trabucchi M. , Cheney D. L. , Susheela A. K. , Costa E.
Published: October 2006

Abstract—

The cholinoacetyltransferase activity (CAT) in diaphragm of mice of Bar Harbor strain (129 ReJ dy/dy) with muscular dystrophy was significantly lower than that of phenotypically normal litter mates (129 ReJ dy/+). CAT, tyrosine hydroxylase (TH), dopamine‐β‐hydroxylase (DβH) activities were found identical in adrenal gland and brain homogenates of normal and dystrophic mice. Subacute injections of atropine (72 μmol/kg i. p., twice daily for 3 days) failed to increase the activity of adrenal CAT in dystrophic mice but increased this enzyme activity in adrenals of normal litter mates. The concentration in brain of dopamine, norepinephrine, serotonin, acetylcholine (ACh), γ‐aminobutyric acid (GABA) and some of their precursors were measured. Only the concentration of ACh was significantly lower in the brain of muscular dystrophic mice. The rate of accumulation of brain ACh concentration after the injection of oxotremorine (5μmol/kg i. p.) is slower in muscular dystrophic animals than in normal litter mates. Furthermore, the turnover rate of ACh in total brain was slower in muscular dystrophic mice than in phenotypically normal litter mates. The turnover rate of brain dopamine and norepinephrine in these 2 groups of animals was similar.
OBSERVATION ON THE PROPERTIES OF DOPAMINE‐β‐HYDROXYLASE1
Authors: Brown F. C. , Harralson J. D.
Published: October 2006

Abstract—

The activity of dopamine‐β‐hydroxylase is inhibited by copper. It is stimulated by a variety of substances, such as fumarate and sodium chloride, which exert salt‐like effects. Both phenomena are mediated indirectly through an interaction of ascorbate with catalase. The latter is converted to the inactive catalase II, by the autoxidation of ascorbate and other electron donors. Copper accelerates the autoxidation, thereby enhancing the inactivation of catalase. The activity of DβH, which requires catalase, is therefore inhibited. At high ionic strength, i. e. in the presence of high levels of salt, the conversion of catalase to catalase II is prevented, and the DβH reaction proceeds.
POLYADENYLIC ACID‐CONTAINING RNA FROM RAT BRAIN
Authors: DeLarco J. , Abramowitz A. , Bromwell Katherine , Guroff G.
Published: October 2006

Abstract—

A portion of rat brain RNA contains poly(A) sequences and binds to oligo(dT)‐cellulose. Young rats have a greater amount of brain RNA which contains poly(A) than do adult animals. The length of the poly(A) sequence from the brain RNA of young animals was shown to be somewhat longer than that from the RNA of adults. The RNA which bound to the oligo(dT)‐cellulose was found to be large and heterogeneous, and to be almost free of ribosomal or of small mol. wt. RNAs. When the polysomal RNA which bound to the oligo(dT)‐cellulose columns and that which did not were used to prime a cell‐free protein synthesizing system there was a noticeable difference in their‘messenger’activity; the RNA which bound to the oligo(dT)‐cellulose was much more active than the unbound material. However, in the case of the nuclear RNA there was not as great a difference between the material which was bound and that which was not bound.
THE EFFECT OF ELECTRICAL STIMULATION ON THE TURNOVER OF PHOSPHATIDIC ACID IN SYNAPTOSOMES FROM GUINEA‐PIG BRAIN
Authors: Bleasdale J. E. , Hawthorne J. N.
Published: October 2006

Abstract—

Synaptosomes prepared from guinea‐pig cerebral cortex were suspended in a medium containing [32P]orthophosphate and subjected to electrical stimulation. When the synaptosomal phospholipids were subsequently separated, the most highly labelled was phosphatidic acid and electrical stimulation over a 10 min period increased incorporation of 32P1 into this lipid. Stimulated synaptosomes were osmotically lysed and subsynaptosomal fractions isolated. The electrically stimulated increase in phosphatidic acid labelling was localized in a fraction enriched in synaptic vesicles. This phospholipid effect was not merely a reflection of an increased specific radioactivity of synaptosomal ATP, due to the electrically stimulated increase in respiration. The time course of the phosphatidic acid effect suggests that it is synchronous with release of transmitter.
GABA AND ITS RELATED ENZYMES IN THE LOWER AUDITORY SYSTEM OF THE GUINEA PIG1
Authors: Fisher S. K. , Davies W. E.
Published: October 2006

Abstract—

The possible existence of GABA‐transmitter neurons in the lower auditory system of the guinea pig has been investigated by means of three different experimental approaches: (1) the regional distribution of GABA and its related enzymes. (2) the subcellular distribution of glutamate decarboxylase, and (3) the effect of selected nerve lesions on glutamate decarboxylase concentrations in the auditory nuclei. Within the regions investigated considerable variations in glutamate decarboxylase activity and GABA concentration were found, with the highest values observed in the inferior colliculus. The dorsal cochlear nucleus also contained significant amounts of both glutamate decarboxylase and GABA, in addition to high concentrations of GABA transaminase. The subcellular distribution of glutamate decarboxylase was bimodal in both the cochlear nucleus and inferior colliculus with most enzyme activity recovered in the soluble and synaptosomal fractions. Neither end organ (cochlea) nor trapezoid body lesions induced a significant loss of glutamate decarboxylase activity in either the cochlear nucleus or inferior colliculus. The results suggest the presence of short axon GABAergic interneurons in the cochlear nucleus, most of which appear to terminate within the dorsal cochlear nucleus.
STUDIES ON THE SYNTHESIS AND DEGRADATION OF DNA IN DEVELOPING AND OLD CHICK CEREBELLUM
Authors: Rao K. Subba , Shrivastaw K. P.
Published: October 2006

Abstract—

The levels of DNA, RNA, protein and acid and alkaline DNase were studied in developing and old chick cerebellum. The in vitro synthesis of DNA, by both chick cerebrum and cerebellum was also studied, by following the incorporation of [3H]thymidine into DNA. It was observed that the increase in DNA content of chick cerebellum continued well beyond adult stages of life span. Maximal DNA synthesis, as judged by the [3H]thymidine incorporation, was noticed during the early embryonic development but decreased with advancement of age. There was, however, another peak of activity, although smaller, at about 9 months of age. Both cerebrum and cerebellum showed similar patterns. The highest specific activity of acid DNase was also found during the early period of cerebellar development, that is at a time when rapid cellular proliferation was occurring. The activity steadily declined with the aging and in 2‐year‐old cerebellum very little activity could be detected. Alkaline DNase, on the other hand, not only exhibited high activity during the early development but also remained at a significant level even in old cerebellum. It is concluded that acid DNase shows a positive correlation to the early embryonic DNA synthesis but not to the cell increase occurring in old age.
A BRAIN‐SPECIFIC PROTEIN WITH AFFINITY FOR DNA1
Authors: Miani N. , Caniglia A. , Panetta V.
Published: October 2006

Abstract— A procedure has been developed which allows the isolation from rat brain cytosol of a soluble acidic protein, designated DNA‐110 protein, having two basic properties: selective affinity for single‐stranded DNA and immunological specificity to the nervous system. Only two major purification steps, DNA‐cellulose chromatography and affinity chromatography on immunoadsorbents are needed to give apparently pure protein. The purification steps of the DNA‐110 protein have been followed by immunological assay. DNA‐110 has a molecular weight of 68,000 and an isoelectric point of 5.9. It accounts for 1.95% of the total soluble protein and its concentration is 216 μg per g wet weight of rat brain. DNA‐110 is immunologically unrelated to other soluble acidic brain‐specific proteins and glycoproteins.
THE CEREBELLAR GLOMERULUS: ISOLATION AND METABOLIC PROPERTIES OF A PURIFIED FRACTION
Authors: Hamberger A. , Hansson H.‐A. , Lazarewicz J. W. , Lundh T. , Sellström Å.
Published: October 2006

Abstract— A method is described for large scale isolation of glomerular complexes from rabbit cerebellum. The purity of the fraction is 90–95%, measured by quantitative electron microscopy. In addition biochemical markers indicate a high degree of particle integrity. The glomeruli occur as mechanically separable units at 20–40 days of animal age and the amount of protein per particle is 15–20 × 10−11 g. The glomeruli accumulate [3H]GABA, and exhibit both high (Km 15μM) and low (Km 0.5 mM) affinity uptake properties. Glomeruli oxidize α‐glycerophosphate and succinate particularly well, while glutamate, pyruvate and α‐ketoglutarate are less effective as respiratory substrates.
EFFECT OF UNILATERAL VISUAL DEPRIVATION AND VISUAL STIMULATION ON THE ACTIVITIES OF GLUTAMATE DECARBOXYLASE, GABA‐α KETOGLUTARATE TRANSAMINASE, ASPARTATE AMINOTRANSFERASE AND HEXOKINASE OF THE OPTIC LOBE OF THE ADULT PIGEON
Authors: Chakrabarti T. , Daginawala H. F.
Published: October 2006

Abstract— A study was made of the effect of unilateral visual deprivation and stimulation upon the activities of glutamate decarboxylase (EC 4.1.1.15), GABA‐α‐ketoglutarate transaminase (EC 2.6.1.19). aspartate aminotransferase (EC 2.6.1.1) and hexokinase (EC 2.7.1.1) in the optic lobe of the adult pigeon (Columba Livia). Visual deprivation was achieved by eyelid suturing or by enucleation and maintained for 1–9 weeks. Unilateral visual stimulation was maintained for 75 min following 72 h in the dark. A small but significant increase was observed in the activities of glutamate decarboxylase and aspartate aminotransferase after unilateral visual stimulation and a decrease after unilateral enucleation. The activities of GABA‐α‐ketoglutarate transaminase and hexokinase decreased after unilateral visual stimulation and increased after enucleation. Unilateral eyelid suturing resulted in a significant reduction in the activity of glutamate decarboxylase and an increase in the activity of GABA‐α‐ketoglu‐tarate transaminase. Hexokinase activity was, however, unchanged following unilateral eyelid suturing.
UPTAKE AND RELEASE OF NIPECOTIC ACID BY RAT BRAIN SLICES
Authors: Johnston G. A. R. , Stephanson A. L. , Twitchin B.
Published: October 2006

—Nipecotic acid, a potent inhibitor of GABA uptake, is taken up by slices of rat cerebral cortex by a sodium‐dependent, ‘high affinity’ system (Km 11 μM), and can be released from these slices by an increased potassium ion concentration in a calcium‐dependent manner. Nipecotic acid and GABA appear to be taken up by the same osmotically‐sensitive structures. GABA and substances which inhibit GABA uptake also inhibit the uptake of nipecotic acid. GABA can release preloaded nipecotic acid from brain slices, and nipecotic acid can release preloaded GABA. This indicates that GABA and nipecotic acid can be counter‐transported using the same mobile carrier. Nipecotic acid appears to have a higher affinity than GABA for this carrier.
A KINETIC ANALYSIS OF SODIUM DEPENDENT GLUTAMIC ACID TRANSPORT IN PERIPHERAL NERVE
Authors: Wheeler D. D.
Published: October 2006

—The kinetics of sodium dependent glutamic acid transport have been studied in desheathed frog sciatic nerve. Initial velocities have been measured as a function of both glulamic acid and sodium concentration. Lineweaver–Burk plots are constructed from these data, and the kinetic constants describing uptake are estimated. Vmax is unaffected by sodium concentration, which implies that translocation is not directly affected by sodium. K1 is sodium dependent, which implies that sodium affects the affinity of the carrier for glutamic acid. Reciprocal plots of velocity vs [Na] or K1 vs 1/[Na] are linear, suggesting that glutamic acid and sodium are co‐transported on a one‐to‐one basis. t, the sodium concentration giving half maximal velocity of uptake, was found to vary from about 57 mm to 48 mm at glutamic acid concentrations of 1.0–10.0 ± 10−6m. A model of a mechanism by which sodium and glutamate could be co‐transported is presented; the model is in very good agreement with the experimental data.
EFFECT OF NEOMYCIN ON PHOSPHOINOSITIDE LABELLING AND CALCIUM BINDING IN GUINEA‐PIG INNER EAR TISSUES IN VIVO AND IN VITRO1
Authors: Orsulakova Angela , Stockhorst Eva , Schacht Jochen
Published: October 2006

—Phospholipids of guinea‐pig inner ear tissues were labelled in vivo by perilymphatic perfusion of the cochlea with [32P]orthophosphate or myo‐[3H]inositol. After 20‐40 min the most highly labelled 32P‐lipids were phosphatidylinositol phosphate and diphosphate. Incorporation of [3H]inositol proceeded in the order phosphatidylinositol > phosphatidylinositol phosphate > phosphatidylinositol diphosphate.

After treatment of animals with neomycin for 3 weeks, 32P‐incorporation into phosphatidylinositol diphosphate, but not into other lipids, was significantly decreased in the preparations of the organ of Corti and stria vascularis. In homogenates of inner ear tissues, the labelling of the polyphosphoinositides by [γ‐32P]ATP was increased and the hydrolysis of these lipids was blocked in the presence of 10−4m‐neomycin. Neomycin also competitively inhibited the binding of 45Ca2+ to homogenates of these tissues.