bluuebunny/crossref_metadata_2025 huggingface dataset:
FLAME PHOTOMETRIC ANALYSIS OF SODIUM AND POTASSIUM IN NANOGRAM SAMPLES OF MAMMALIAN NERVOUS TISSUE
Authors: Keesey J. C.
Published: October 2006

Abstract—

A dual‐channel integrating micro‐flame‐photometer was evaluated for simultaneous analysis of sodium and potassium in aqueous extracts from nanogram samples of frozen‐dried mammalian nervous tissue. Calibrated quartz constriction micropipettes delivered 10−8 l. of extraction fluid to a 100 μ platinum‐iridium wire for insertion directly into the flame. Over‐all reproducibility was 4 per cent for twenty samples containing 6.5 × 10−11 g K and 2.2 × 10−11 g Na. Large amounts of anions decreased the emissions for both sodium and potassium, but no interference between sodium and potassium was found over the range adopted for biological analyses. The micro‐flame‐photometer gave results for a few nanolitres of aqueous extracts of brain homogenates which were within 3‐5 per cent of those obtained on larger volumes with a conventional flame photometer. Macroanalysis and microanalyses of microgram quantities of frozen‐dried tissue sections of cerebral cortex were also in agreement. Nanogram samples from frozen‐dried spinal ganglia of a rabbit gave average values for sodium and potassium (calculated/g wet wt.) which were similar to those for aqueous extracts of rabbit brain homogenates. Samples from peripheral ganglia in vivo, 10 minpost mortem and 20 min post mortem had significantly different average K/Na ratios of 1.97, 2.64 and 3.23, respectively.
QUANTITATIVE HISTOCHEMISTRY OF NICOTINAMIDE ADENINE NUCLEOTIDES IN RETINA OF MONKEY AND RABBIT1
Authors: Matschinsky F. M.
Published: October 2006

Abstract—

The levels of NADP+, NADPH, NAD+ and NADH were measured in the different layers of retinas from rabbit and monkey. Samples (0.1 μg) were dissected from frozen‐dried sections. The sum of oxidized and reduced forms was obtained by analysis of samples diluted several thousand fold in 0.02 n‐NaOH at 0°. The reduced forms were measured by analysis of the same alkaline preparation after heating to destroy NADP+ and NAD+. All assays were made at 1:100,000 tissue dilution by enzymic cycling, which is capable of measuring 10−14 moles of nucleotides.

Profiles of nicotinamide adenine nucleotide levels werecomparable in monkey and rabbit. Both total NADP and NAD were lowest in the outer segments of the retina and highest in the inner layers. NADP of the outer layers (1‐2b) was oxidized to a high degree. This was particularly striking for layer 2b, which is rich in mitochondria. In the inner layers the fraction of NADPH rose to 0.7 of the total NADP. NAD on the contrary was highly oxidized in all ten layers of the retina.

Three aspects of these results seem significant: (1) The profile for NADP was not related to the distribution of any of four major NADP‐requiring dehydrogenases or their sum; (2) the ratio of total NADP/NADPH in the mitochondrial layer was much higher than expected from studies with isolated mitochondria; and (3) the amount of total NADP was surprisingly high in non‐mitochondrial layers.
SODIUM‐STIMULATED ADENOSINE TRIPHOSPHATASE ACTIVITY OF RAT BRAIN MITOCHONDRIA
Authors: Beattie Diana S. , Basford R. E.
Published: October 2006

Abstract The endogenous ATPase activity of rat brain mitochondria was stimulated 30‐50 per cent by 15‐50 mm concentrations of NaCl or Na acetate. The Na stimulation was completely abolished by small amounts of oligomycin but unaffected by ouabain. The differential effects of these inhibitors indicated that the Na‐induced ATPase activity did not result from microsomal or synaptosomal contamination of mitochrondria. Sodium salts decreased the stimulatory effects of DNP, gramicidin, or Ca, but not that of Mg on the endogenous ATPase activity. These interactions were specific for Na+ as the corresponding salts of K+ did not affect the endogenous ATPase or inhibit the DNP‐stimulated ATPase activity except at high concentrations. The Na‐induced increases in ATPase activity and respiration were more sensitive to aging of the mitochondria than were ADP/O and respiratory control ratios, or the DNP‐induced ATPase activity. These results suggest that Na+ may interact in brain mitochondria with the same high‐energy intermediate of oxidative phosphorylation proposed for DNP and Ca.
METABOLISM OF [14C]LEUCINE AND [14C]ACETATE IN SENSORIMOTOR CORTEX, THALAMUS, CAUDATE NUCLEUS AND CEREBELLUM OF THE CAT
Authors: Berl S. , Frigyesi T. L.
Published: October 2006

Abstract— —In the head of the caudate nucleus, the relative specific activity of glutamine (glutamic acid specific activity = 1) was less than 1 with intravenous [14C]leucine as the tracer metabolite. This is in contrast to observations made in other brain areas (cortex, hippocampus, thalamus, pons, and medulla) where the relative specific activity of glutamine was greater than 1. This is also in contrast to findings when [l‐14C]acetate was utilized as the tracer; under these conditions, in all brain areas, including the head of the caudate nucleus, the relative specific activity of glutamine was greater than 1. It is inferred that the differences in metabolism of [14C]leucine and [14C]acetate in the head of the caudate from that in other brain areas reflect differences in compartmentation of the glutamate‐glutamine system.
INFLUX OF GLUTAMIC ACID IN PERIPHERAL NERVE—CHARACTERISTICS OF INFLUX1
Authors: Wheeler D. D. , Boyarsky L. L.
Published: October 2006

Abstract— —The influx of glutamic acid in frog sciatic nerve has been studied by monitoring the disappearance of 14C labelled compound from the bathing medium. After 5hr of incubation in 10 −6m non‐labelled l‐glutamic acid and 0·01, μc/ml labelled isotope, the intracellular concentration of labelled glutamic acid is about 15 times the concentration in the bathing medium; however, there appears to be a net loss of non‐labelled compound with incubation. Uptake of L,‐glutamic acid is accompanied by conversion of significant amounts of labelled E‐glutamic acid to carbon dioxide and glutamine; small amounts of γ‐aminobutyric acid and aspartic acid are also formed. The rate of disappearance of labelled l‐glutamic acid decreases with increasing concentration of non‐labelled isotope in the bathing medium. Construction of a Lineweaver‐Burk plot from initial velocities of influx yields an average Vm of 4·02 × 10−9 moles/g/min and an average Km. of 3·23 × 10 −5 moles/l. The influx of glutamic acid is highly specific with regard to molecular structure; of the compounds tested, only l‐glutamine, l‐glutamic acid, GABA, l‐lysine, and l‐aspartic acid are taken up, and only l‐aspartic acid will compete with l‐glutamic acid for uptake.
LIPID COMPOSITION OF GLIAL CELLS ISOLATED FROM BOVINE WHITE MATTER
Authors: Fewster Mona E. , Mead J. F.
Published: October 2006

Abstract— —Glial cells were isolated from bovine white matter by differential centrifugation with‘Ficoll’and their lipid composition was analysed. The preparations contained 20.8 per cent lipid and 792 per cent protein. The major lipid components were cholesterol, ethanolamine glycerophosphatides (EGP), cerebroside and serine glycerophosphatides (SGP). Sphingomyelin, cerebroside sulphate and inositol glycerophosphatide were present in lower proportions. EGP contained the largest proportion of aldehydes (17 per cent) and SGP contained 12 per cent. Choline glycerophosphatides contained only a trace of aldehyde. No gangliosides were present in the filial cell preparations.
COMPARISON OF LIPID EFFECTS ON K+‐Mg2+ ACTIVATED p‐NITROPHENYL PHOSPHATASE AND Na+‐K+‐Mg2+ ACTIVATED ADENOSINE TRIPHOSPHATASE OF MEMBRANE1
Authors: Tanaka R.
Published: October 2006

Abstract— A comparison was made between K+‐Mg2+ activated p‐nitrophenyl phosphatase and Na+‐K+‐Mg2+ activated adenosine triphosphatase with a solubilized enzyme preparation from a membrane fraction of cerebral cortex. The NPPase showed activity even in the absence of phospholipid, whereas the ATPase required the lipid for its activity. More varied types of phospholipids were effective in activating the NPPase than the ATPase, and with each phospholipid the extent and the pattern of the NPPase activation differed from that of the ATPase. By deoxycholate treatment the pH optimum of the NPPase was shifted independently from the pH optimum shift of the ATPase. The specific activity ratio of the NPPase to the ATPase was not constant during purification. These two enzymes were, however, not separable with ammonium sulphate fractionation, and their thermo‐lability was identical regardless of the presence of phospholipid. The results suggested two possibilities: (1) the NPPase is a separate enzyme entity from the ATPase; (2) although the NPPase is a part of the ATPase system, the mechanism of action of lipids on the former part differs from that on the rest of the system.
DNA SYNTHESIS IN THE GLIAL CELLS OF SCRAPIE‐AFFECTED MOUSE BRAIN
Authors: Kimberlin R. H. , Anger H. S.
Published: October 2006

Abstract—

Radioautographic techniques have been used to study the incorporation of [3H]‐thymidine into the DNA of glial cells in normal and scrapie‐affected mouse brain. Some differences were seen in the morphological distribution and also in the size distribution of labelled nuclei in sagittal sections of normal and affected brain. Counts of the total number of labelled nuclei per sagittal section showed a progressive decline from 50 to 15 per section in normal brain over the 4‐month experimental period. However, in scrapie‐affected brain the number increased markedly to 120 per section 5‐6 weeks after inoculation and stayed at this level for the remaining 9‐10 weeks of the incubation period. The significance of these results in relation to the pathogenesis of scrapie is discussed.
DISTRIBUTION OF SOME ENZYMES ASSOCIATED WITH THE METABOLISM OF GLUTAMATE, ASPARTATE, γ‐AMINOBUTYRATE AND GLUTAMINE IN CAT SPINAL CORD1
Authors: Graham L. T. , Aprison M. H.
Published: October 2006

Abstract—

The activities of glutamine synthetase, glutaminase, glutamate decarboxylase, GABA aminotransferase, glutamate dehydrogenase, and aspartate aminotransferase were measured in four areas of the cat spinal cord and in dorsal and ventral roots. Five of the six enzymes showed identical distribution patterns; i.e. the activities in the dorsal and ventral gray matter were equal and those of dorsal and ventral white matter were equal. No statistical differences in the mean enzyme activities in the dorsal and ventral roots were found. Glutamate decarboxylase was the only enzyme which had a different pattern. The enzyme activity in dorsal gray was twice that of ventral gray; the same pattern as the GABA concentration in both these areas. The glutamine synthetase activities in the cord areas and roots correlated with the glutamine distribution reported earlier. Thus, the distribution of glutamine (not a transmitter) and GABA (questionable transmitter) in gray matter are dictated by their synthesizing enzymes, whereas the distribution of glutamate and aspartate (likely transmitter suspects) cannot be explained on the basis of enzyme activities. Therefore, the enzyme activities may be related to the amino acid levels primarily in metabolic compartments, whereas the excess of certain amino acids in specific areas of the cord and roots may be related to functional compartments accumulated for use in synaptic transmission.
ISOLATION OF SYNAPTIC COMPLEXES IN A CAESIUM CHLORIDE DENSITY GRADIENT: ELECTRON MICROSCOPIC AND IMMUNOHISTOCHEMICAL STUDIES1
Authors: Kornguth S. E. , Anderson J. W. , Scott G.
Published: October 2006

Abstract—

A technique is described for the improved isolation of synaptic complexes. Homogenates of guinea pig cerebellum and cerebral cortex were subjected to centrifugation, first in a discontinuous sucrose gradient, and secondly in a continuous caesium chloride gradient. Of the six bands that were obtained, band four contained a high proportion of synaptic complexes showing both pre‐ and postsynaptic elements attached to each other; myelin and free mitochondria were not contaminants of this fraction. Fluorescein‐labelled γ‐globulin prepared against band four reacted with synaptic regions of cerebellum and cerebral cortex, but not with cervical cord.
METABOLISM OF HEXOSES IN RAT CEREBRAL CORTEX SLICES
Authors: Chain E. B. , Rose S. P. R. , Masi Ines , Pocchiari F.
Published: October 2006

Abstract—

The metabolism of two 14C‐labelled hexoses and one hexose analogue, viz. mannose, fructose and glucosamine, has been compared with that of glucose for slices of rat cerebral cortex incubated in vitro.

The metabolism of [U‐14C]mannose was essentially identical to that of glucose; oxygen consumption and CO3 production were similar and maximal at a substrate concentration of 2·75 mM. Incorporation of label into lactate, aspartate, glutamate and GABA was similar for the two substrates at 5·5 mM substrate concentration.

With [U‐14C]fructose, maximal oxygen consumption and CO3 production were obtained at a substrate concentration of 11 mM. At 5·5 mM, incorporation into lactate was 5 per cent, into glutamate and GABA 30 per cent, into alanine 63 per cent and into aspartate 152 per cent of that from glucose. Increasing substrate concentration to 27·5 mm was without effect on incorporation into amino acids from glucose and raised incorporation from fructose into glutamate, GABA and alanine to a level similar to that found with glucose; at the higher substrate concentration aspartate incorporation from fructose was 200 per cent and lactate 42 per cent of that with glucose. Unlabelled fructose was without effect on incorporation of radioactivity from [3‐14C]pyruvate into CO2 or amino acids; it increased incorporation into lactate by 36 per cent. Unlabelled glucose diminished incorporation into CO2 from [U‐14C]fructose to 35 per cent; incorporation into lactate was stimulated 178 per cent at 5·5 mM fructose; at 27·5 mM it was diminished to 75 per cent.

By comparison with [1‐14C]glucose, incorporation of radioactivity from [1‐14C]‐glucosamine into lactate, CO2, alanine, GABA and glutamine was very low; incorporation into aspartate was similar to glucose. Thus the metabolism of glucosamine resembled that of fructose. Glucosamine‐1‐phosphate, glucosamine‐6‐phosphate, and an unidentified metabolite, all accumulated.
THE OXIDATION OF GLYCINE BY d‐AMINO ACID OXIDASE IN EXTRACTS OF MAMMALIAN CENTRAL NERVOUS TISSUE
Authors: de Marchi Wilhelmina J. , Johnston G. A. R.
Published: October 2006

Abstract— Glycine was a substrate for d‐amino acid oxidase purified from extracts of cat spinal cord and sheep cerebellum. d‐Aspartate and N‐methyl‐d‐aspartate were oxidized at a rate similar to that of glycine by the purified sheep cerebellum extract; d‐α‐alanine and d‐serine were oxidized appreciably faster than glycine, while GABA and d‐glutamate were not oxidized at a measurable rate. p‐Mercuribenzoate and kojate inhibited the oxidation of glycine by the purified sheep cerebellum extract.

d‐Amino acid oxidase activity was higher in the grey than in the white matter of cat spinal cord, while the reverse was true for the cerebral cortex; the activity in the cord and cerebral cortex was much lower than that in the cerebellum.
COMPOSITION OF CEREBRAL LIPIDS IN MURINE SUDANOPHILIC LEUCODYSTROPHY: THE JIMPY MUTANT
Authors: Hogan E. L , Joseph K. C , Schmidt G
Published: October 2006

Abstract— The composition of sphingolipids and phospholipids of mouse brain during myelination was determined in normal animals and in mice with a genetically‐determined disorder of myelin formation. Myelination was normally characterized by a two‐fold increase in total phospholipids of brain, a four‐fold increase in total sphingolipids, and a six‐fold increase in cerebrosides. The Jimpy mutant, with defective formation of myelin in the central nervous system, demonstrated a marked deficiency of cerebrosides and a significantly lower content of total sphingolipids, without alteration of the composition of phospholipids. The increasing content of cerebrosides in the brains of the leucodystrophic mutant at the time in development when myelination is most active and the subsequent relative deficit suggest that the failure of myelin formation is not the result of a defect in biosynthesis of cerebrosides.
SOME NEUROCHEMICAL ASPECTS OF PENTAMETHYL‐ENETETRAZOLE CONVULSIVE ACTIVITY IN RAT BRAIN
Authors: Nahorski S. R , Roberts D. J , Stewart G. G
Published: October 2006

Abstract— The concentrations of several metabolites, including glucose, glycogen, hexose phosphates, adenine nucleotides, amino acids and some tricarboxylic cycle intermediates were estimated in cerebral tissue of rats killed at various stages of pentamethylenetetrazole convulsions. Prior to and during the seizure there was an increase in glycolytic flux and depletion of energy reserves. An accumulation of alanine concomitant with a decreased citrate level observed before the convulsion indicated that a possible interference of pyruvate entry into the tricarboxylic cycle had occurred. At the tonic extensor phase of the seizure and during post‐convulsive sedation a small but significant rise in GABA and an attempt to restore some of the labile constituents to more normal values was apparent. The significance of these results in relation to cerebral metabolic control and possible mechanisms of initiation and arrest of the seizure is discussed.
ASSAY AND SUBCELLULAR LOCALIZATION OF THE ARYLSULPHATASES IN RAT BRAIN1
Authors: Clendenon N. R. , Allen N.
Published: October 2006

—The properties and subcellular localization of type I (nitrophenyl) and type II (nitrocatechol) arylsulphatases were investigated in brain tissue of the rat, and optimal assay conditions were established. Sulphate, phosphate and sulphite ions inhibited the nitrocatechol sulphatases; nitrophenyl sulphatase was inhibited only by sulphite. The presence of latent enzyme activity was demonstrated for the nitrocatechol sulphatases, beta‐glucuronidase, and beta‐glycerophosphatase in rat and mouse brain homogenates. These hydrolases were highly sensitive to mechanical and osmotic damage; and Triton X‐100 was very effective in releasing their latent (bound) activities, a finding suggestive of a lysosomal localization. Activity of nitrophenyl sulphatase was unaffected by osmotic changes or Triton X‐100, characteristics suggesting a membranous association for this enzyme. Total activity of nitrophenyl sulphatase was approximately twice as great in canine gray matter as in canine white matter; the converse obtained for beta‐glucuronidase activity. Values for total enzymic activity of the nitrocatechol sulphatases in canine white and gray matter were similar.

Fractionation of homogenates from rat brain by differential centrifugations and separation of crude mitochondrial fractions by sucrose density gradient centrifugations revealed the following: (1) most of the nitrocatechol sulphatase activity (93 per cent) and all of the nitrophenyl sulphatase activity were sedimentable; (2) crude mitochondrial fractions exhibited the highest relative specific activity (RSA = 1·38) for the nitrocatechol sulphatases, whereas microsomal fractions displayed the highest RSA for nitrophenyl sulphatase (1·89); (3) the lightest fraction (A + B) and the densest fraction (E) from the sucrose density gradient contained most of the activity for both the type I and type II arylsulphatases, whereas the RSA of cytochrome oxidase was greatest in the intermediate density regions (fractions C and D); (4) the highest RSA for beta‐glucuronidase and beta‐glycerophosphatase occurred in gradient fraction C; (5) appreciable activity of beta‐glycerophosphatase was found in a nerve ending fraction (M3).

It is suggested that the hydrolases in heterogeneous tissue like brain might be associated with lysosomal particles of differing enzyme compositions and varying populations, and that the data on distribution lend credence to the concept of bimodal and possible trimodal particle affinity for the hydrolases of brain tissues.
THE EFFECT OF SPIKE ACTIVITY VERSUS SYNAPTIC ACTIVATION ON THE METABOLISM OF RIBONUCLEIC ACID IN A MOLLUSCAN GIANT NEURONE
Authors: Kernell Daniel , Price Peterson R.
Published: October 2006

—Previous experiments on a giant neurone (R2) from Aplysia californica have shown that a prolonged electrical stimulation of ganglionic nerves, strong enough to elicit post‐synaptic spikes in the giant neurone, caused a marked increase in the uptake of labelled nucleosides into the neuronal RNA. The results described in the present paper very strongly indicate that these effects of synaptic activation were not due to the discharge of spikes in the giant neurone itself. Spikes which were directly elicited in the giant neurone by current pulses injected into the cell through an intracellular microelectrode had no significant effect on RNA labelling. Weak stimulation of ganglionic nerves, eliciting post‐synaptic potentials but few spikes in the giant neurone, produced a small but significant increase of RNA labelling.
TOXIC EFFECTS OF OXYGEN ON CEREBRAL METABOLISM
Authors: Williams Carolyn D. , Haugaard N.
Published: October 2006

Abstract— The effect of 100% O2 at one atmosphere on carbohydrate metabolism in cell‐free homogenates of rat brain was studied under different experimental conditions. The principal findings were the following:

Compared to 10% O2‐90% N2, oxygen at one atmosphere inhibited metabolism of α‐oxoglutarate and depressed the net synthesis of ATP. With glucose as substrate, accumulation of ATP was also markedly inhibited but substrate utilization was only slightly affected.

Glycolysis in brain was relatively resistant to oxygen toxicity, except in the presence of added Cu2+.

With α‐oxoglutarate as the substrate, inhibition of the formation of ATP occurred earlier than inhibition of substrate utilization, indicating the particular sensitivity of oxidative phosphorylation to inactivation by oxygen in vitro.

Cu2+ and Fe2+ accentuated oxygen toxicity but appeared to act by different mechanisms. Co2+ exerted a protective effect.

The sulphydryl compounds, dithiothreitol and reduced glutathione, strongly diminished the toxic effect of oxygen.
THE BIOSYNTHESIS OF CHOLESTEROL AND OTHER STEROLS BY BRAIN TISSUE
Authors: Ramsey R. B. , Jones J. P. , Nicholas H. J.
Published: October 2006

Abstract— The distribution of 14C into several subcellular fractions of adult rat brain was studied as a function of time, following intracerebral injection of [2‐14C]mevalonic acid. As expected from previous studies, the microsomal fraction was indicated as the site of sterol biosynthesis. The myelin fraction showed a marked and early uptake of I4C‐labelled, digitonin‐precipitable material. This was assumed to be a non‐enzymic uptake of sterol intermediates. The mitochondrial fraction exhibited a rapid uptake of 14C‐labelled, nonsaponifiable material, but a very slow accumulation of 14C‐labelled, digitonin‐precipitable product. Examination of the nonsaponifiable 14C‐fractions by TLC showed a rapid appearance of labelled 4‐desmethyl sterols in the microsomal fraction. The myelin fraction selectively retained 4,4′‐dimethyl sterol but seemed to release this with time, possibly to be further metabolized by the microsomes. Examination of [14C]digitonin‐precipitable material by the dibromide method showed that although labelled 4‐desmethyl sterol appeared quite early, cholesterol itself was formed slowly in all fractions.
THE FATTY ACID COMPOSITION OF PHOSPHOLIPIDS AND GLYCOLIPIDS IN JIMPY MOUSE BRAIN
Authors: Nussbaum J. L. , Neskovic N. , Mandel P.
Published: October 2006

Abstract— Phospholipids and sphingolipids from brains of normal and Jimpy mice were isolated in a pure form by thin‐layer chromatographic procedures. The fatty acid composition of the major phospholipids, i.e. ethanolamine glycerophospholipids, serine glycerophospholipids, choline glycerophospholipids and inositol glycerophospholipids, as well as sphingomyelin, cerebrosides and sulphatides was determined by gas‐liquid chromatography. A specific fatty acid pattern for each of the four glycerophospholipids was found. The fatty acid composition of inositol glycerophospholipid, which has not previously been studied in mouse brain, was characterized by a high concentration of arachidonic acid. After 16 days of age, fatty acid analysis showed definite differences between the phospholipids from normal and mutant brains. A small increase of polyunsaturated fatty acids in glycerophospholipids of ethanolamine, serine and choline from the Jimpy central nervous system was found, which has been explained by the myelin deficiency. Sphingomyelin, cerebrosides and sulphatide analyses showed a wide distribution of saturated and mono‐unsaturated fatty acids in both normal and mutant mice. A reduction in the amount of long‐chain fatty acids was demonstrated in mutant brain sphingolipids; in sulphatides and cerebrosides, the amount of non‐hydroxy fatty acids was reduced to a greater extent than in sphingomyelin.

The distribution of fatty acids in sphingolipids from the myelin and microsomal fractions was also investigated in both types of mice. Cerebrosides were characterized by a high content of long‐chain fatty acids in myelin as well as in microsomes. Sulphatides and sphingomyelin, on the other hand, showed a higher content of medium‐chain fatty acids in microsomes than in myelin. In the mutant brain, the amount of long‐chain fatty acids was reduced in both subcellular fractions. The deviation from normal in the pattern of fatty acid distribution in Jimpy brain is discussed in relation to the current concepts of glycolipid biosynthesis.
OCCURRENCE AND PROPERTIES OF CATECHOL‐O‐METHYL TRANSFERASE IN ADRENERGIC NEURONS
Authors: Jarrott B.
Published: October 2006

—A study has been made of the catechol‐O‐methyl transferase activity of some peripheral tissues after sympathetic denervation. A fall in catechol‐O‐methyl transferase activity was found in some organs, e.g. rat and rabbit vas deferens, cat nictitating membrane and rabbit submaxillary gland but not in mouse heart and spleen. It was found that suboptimal concentrations of S‐adenosylmethionine did not reveal a significant difference between normal and denervated organs but at optimal concentrations a fall was seen in some organs. Catechol‐O‐methyl transferase activity was present in bovine splenic nerve and in adrenal medulla. It is suggested that the fall in enzyme activity after denervation indicates a neuronal cellular localization. A kinetic study of catechol‐O‐methyl transferase from normal and denervated rat vas deferens suggested that the neuronal and extraneuronal catechol‐O‐methyl transferase had different kinetic properties and an estimation of the kinetic constants of the neuronal enzyme was made.
RELEASE OF [3H]NORADRENALINE AND [3H]DOPAMINE FROM FIELD STIMULATED CEREBRAL CORTEX SLICES EFFECT OF TYROSINE HYDROXYLASE AND DOPAMINE‐β‐HYDROXYLASE INHIBITION.1
Authors: Farnebo L.‐O. , Hamberger B. , Jonsson G.
Published: October 2006

Abstract—

Rat cerebral cortex slices were incubated in vitro with [3H]dopamine (DA) or [3H]noradrenaline (NA) (10−7M), superfused by fresh buffer and stimulated by an electric field. The stimulation‐induced overflow of [3H]DA and [3H]NA was determined.

In slices from untreated rats about 16 ng [3H]NA/g tissue was formed from [3H]DA, corresponding to about 5 per cent of the endogenous NA concentration. Stimulation markedly enhanced the overflow of [3H]NA. The [3H]NA newly formed from [3H]DA was overflowing to a greater extent than [3H]NA previously taken up from the incubation medium, indicating a preferential release of newly synthesized transmitter. The stimulation‐induced overflow of [3H]DA and [3H]NA was increased in slices of rats pretreated with a tyrosine hydroxylase inhibitor (H44/68). It seems that depletion of the endogenous NA stores of central NA neurons by tyrosine hydroxylase inhibition makes the [3H]cate‐cholamines more available for release. Pretreatment of the rats with the DA‐β‐hydroxylase inhibitors FLA63 or FLA69 considerably diminished the formation of [3H]NA from [3H]DA. Stimulation markedly enhanced the overflow of [3H]DA indicating that DA can act as a ‘false transmitter’ in central NA neurons after DA‐β‐hydroxylase inhibition.
QUANTITATIVE DETERMINATION OF DNA IN PRESERVED BRAINS AND BRAIN SECTIONS1
Authors: Zamenhof S. , Grauel Ludmila , Van Marthens Edith , Stillinger R. A.
Published: October 2006

Abstract— Existing methods for the colorimetric (diphenylamine) determination of DNA content of brain have been modified for preserved cerebral hemispheres. On the average, right and left hemispheres (rat and chicken) contained similar amounts of DNA and one hemisphere could serve as a control for the other. All comparisons have been made with the values obtained for frozen brains (‘controls’). Preservation in 10 % (v/v) buffered formalin for 1 month introduced significant differences for both neonatal and adult cerebral hemispheres. On the other hand, preservation in 75 % (v/v) aqueous ethanol for 1 month did not introduce any significant differences in any of these determinations. Embedding in paraffin and subsequent clarification (removal of paraffin) did not further affect the DNA values of cerebral hemispheres preserved in formalin. Consequently it was possible to determine DNA in histological sections at the desired planes or even in parts of the sections. Micro‐modifications have been devised to determine colorimetrically the total DNA content of small brains (e.g. tadpoles) or of small parts of larger brains, as low as 25 μg of DNA/sample.
INCORPORATION OF 3H‐LABELLED LEUCINE INTO THE PROTEIN FRACTION IN THE RETINA OF THE HONEYBEE DRONE
Authors: Pepe I. M. , Baumann F.
Published: October 2006

Abstract— Protein synthesis in the retina of the honey‐bee drone was studied by incubating head slices in labelled leucine and measuring the TCA insoluble radioactivity. It was found that the protein‐bound radioactivity in illuminated retinas was half of that in dark‐adapted ones. This ratio was not affected by pre‐treatment with puromycin. It was therefore concluded that, in the drone, the main influence of illumination is to increase the rate of breakdown of proteins.

Relatively high concentrations of labelled protein were found in dark‐adapted retinas when the retinula cells were hyperpolarized by bathing the preparation in a sodiumfree medium; low concentrations were found when retinula cells were depolarized by increasing the extracellular potassium concentration. These findings suggest that protein metabolism of the retina is influenced by the membrane potential of retinula cells.
DISTRIBUTION OF RIBOSOMAL MATERIAL IN INCUBATED AND ELECTRICALLY STIMULATED CEREBRAL SLICES
Authors: Ornellas M. R. , Jones D. A.
Published: October 2006

Abstract— The distribution of ribosomal fractions has been examined in fresh cerebral cortex tissue and in slices maintained in vitro both with and without electrical stimulation. The electrical stimulation used was of a type that has previously been shown to diminish amino acid incorporation into protein.

Membrane‐bound and free fractions were obtained and the ratio of their RNA contents were, for the control tissue 3, and for the electrically stimulated tissue 1, 8. Electrical stimulation was found to decrease the Mg2+ binding affinity of the free. fraction but was without effect on the bound fraction. Stimulation was also found to increase the leakage of soluble protein and RNA from the tissue and its accumulation in the incubation medium.
THE COMPOSITION OF MYELIN FROM THE MUTANT MOUSE ‘QUAKING’
Authors: Gregson N. A. , Oxberry J. M.
Published: October 2006

Abstract— Myelin was isolated from the brains of adult Quaking mice, a mutant showing a deficiency of myelin in the central nervous system, and normal controls. The mutant myelin was found to have a higher flotation density than that of the control and showed marked differences in lipid composition. The myelin from Quaking mice was found to be deficient in cerebroside and ethanolamine phospholipid. Acrylamide gel electrophoresis of total myelin protein demonstrated a pronounced deficiency of proteolipid protein. The activity of cyclic 2′,3′‐AMP phosphohydrolase was normal.
INHIBITION OF CHOLINE ACETYLTRANSFERASE AND ITS HISTOCHEMICAL LOCALIZATION
Authors: Kása P. , Morris D.
Published: October 2006

Abstract— A method for the histochemical identification of choline acetyltransferase has been investigated further by studying the effects of certain inhibitors of the enzyme both on rat brain homogenates and on the localization of the enzyme in tissue sections.

It was confirmed that acetyl‐CoA hydrolase activity both in homogenates and in tissue sections is inhibited by preincubation in 1 mM‐DFP. The effects of the choline acetyltransferase inhibitors chloro‐ and bromoacetylcholine on the appearance of histochemical staining were related to their activity in homogenates and tissue slices. Bromoketone was found to inhibit choline acetyltransferase in homogenates and, less efficiently, in tissue sections but it also inhibited the hydrolysis of acetyl‐CoA by some other unknown enzyme which is inactivated by 1 mM‐DFP.

The results obtained with the choline acetyltransferase inhibitors provide support for the specificity of the histochemical method.
COMPETITIVE INHIBITION OF GABA UPTAKE IN RAT BRAIN SLICES BY SOME GABA ANALOGUES OF RESTRICTED CONFORMATION
Authors: Beart P. M. , Johnston G. A. R. , Urn M. L.
Published: October 2006

Abstract— trans‐4‐aminocrotonic acid, dl‐cis‐aminocyclohexane‐ltarboxylic acid and 4‐aminotetrolic acid were found to be competitive inhibitors of GABA uptake in rat brain slices. These inhibitors are analogues of extended conformations of GABA, which indicates that these conformations are important in the initial binding of this inhibitory transmitter to its transport carrier.
DEHYDROEPIANDROSTERONE SULPHATE IN RAT BRAIN: INCORPORATION FROM BLOOD AND METABOLISM IN VIVO12
Authors: Kishimoto Y. , Hoshi M.
Published: October 2006

The incorporation of [7‐3H]dehydroepiandrosterone[35S]sulphate into brain tissue elements from the circulatory system and its metabolic fate in the brain were studied in developing rats. Approximately 0.037 % of [3H] and 0.023% of [35S] were incorporated into the brain within 15 min after the intracardiac injection of the labelled steroid. More than one‐half of the incorporated [3H] was recovered as free steroid, whereas the rest was recovered as sulphate. The 3H/35S ratio in the sulphate fraction suggested that the sulphate entered the brain with the sulphate linkage intact. Upon intracerebral injection of the double‐labelled steroid, approximately 6 per cent of the radioactivity was recovered in the brain at 30 min after the injection and 1 per cent was recovered at 1 h after the injection. Of the remaining radioactivity recovered from the brain, 5 per cent was found in the free steroid fraction, probably formed by hydrolysis of the sulphate; 90 per cent was in the sulphate ester fraction; and the rest was in the fraction of more polar compounds. To identify the metabolites, [4‐14C]dehydroepiandrosterone sulphate was injected into the rat brain. Significant amounts of radioactivity were found in androstenediol sulphate, which was isolated from the brain. This compound was apparently derived from dehydroepiandrosterone sulphate by reduction of the 17‐keto group to a 17β‐hydroxyl group without prior hydrolysis. There was suggestive evidence that free androstenediol was also formed in the brain in this experiment.
THE ACCUMULATION OF ARACHIDONATE AND DOCOSAHEXAENOATE IN THE DEVELOPING RAT BRAIN
Authors: Sinclair A. J. , Crawford M. A.
Published: October 2006

—Fatty acids typical of grey matter lipids (C20:4 and C22:6) and of myelin lipids (C20:1 and C24:1) were estimated in developing rat brains. The polyenoic fatty acids (C20:4 and C22:6) are synthesized from the essential fatty acids (C18:2 and C18:3). The results showed that more than 50 per cent of the adult content of the brain polyenoic acids were laid down by day 15. In contrast, the fatty acids characteristic of myelin lipids did not appear in significant quantities until after this time. These findings distinguish biochemically the different periods of brain development associated firstly with cell division (formation of neurons and glial cells) and secondly with myelination. It is of special interest that the period of cell proliferation is accompanied by the appearance in brain lipids of long‐chain polyenoic acids derived from the essential fatty acids.
TRANSPORT OF GABA FROM THE PERFUSED VENTRICULAR SYSTEM OF THE CAT1
Authors: Snodgrass S. R. , Lorenzo A. V.
Published: October 2006

Abstract— The transport of GABA was studied in anaesthetized cats undergoing ventriculo‐cisternal perfusion with radioactive GABA. Steady‐state clearance of GABA from the CSF was greater than that of other amino acids previously studied, and was saturated at lower substrate concentrations, with an apparent Kt of 5·4 × 10‐5 M, after correcting for non‐saturable transport. GABA clearance was inhibited by the inclusion of taurine or β‐alanine in the perfusion fluid, but not by a number of the common neutral and acidic amino acids. Study of punch biopsies of brain tissue taken adjacent to the venticular system, at the completion of perfusions, showed accumulation of radioactive GABA in the tissue to values four times higher than those found in the perfusion fluid. Of the radioactivity which had been removed from the ventricular system, only 11 per cent remained in the brain at the completion of the perfusion. Excised cat choroid plexus showed a saturable uptake of GABA which was inhibited by inclusion of taurine, β‐alanine, or β‐guanidino propionic acid in the incubation medium.
IMMUNOLOGICAL STUDIES ON A MEMBRANE PROTEIN (CHROMOMEMBRIN B) OF CATECHOLAMINE‐STORING VESICLES
Authors: Hörtnagl Heide , Winkler H. , Lochs H.
Published: October 2006

Abstract— Rabbits were immunized with chromomembrin B, i.e. a membrane protein isolated from chromaffin granules of bovine adrenal medulla. When the rabbit sera were tested by immunodiffusion in the presence of various detergents, only negative results were obtained, whereas with complement fixation antibodies could be demonstrated. With this method the subcellular distribution of chromomembrin B in bovine adrenal medulla was determined. The results demonstrate that this protein is specifically localized in the membranes of chromaffin granules. In the mitochondrial and microsomal fractions it is present only in small amounts which are attributable to a contamination of these fractions with chromaffin granules. The subcellular distribution of chromomembrin R in bovine splenic nerves indicates that this antigen is also found in the membranes of noradrenalinestoring vesicles of sympathetic nerve. Chromomembrin B or a related antigen was detected in chromaffin grades isolated from pig and rat adrenal and in those isolated from a human phaeochromocytoma. It is also present in total membranes obtained from posterior and anterior hypophysis, but it is absent from membranes isolated from parotid gland, liver and adrenal cortex. This paper illustrates how a membrane protein which requires detergents for its solubilization can be characterized and measured by immunological methods.
SUBCELLULAR DISTRIBUTION OF BIOGENIC MONOAMINES IN THE CENTRAL NERVOUS SYSTEM OF ANODONTA CYGNEA L. AS REVEALED BY DENSITY GRADIENT CENTRIFUGATION
Authors: Hiripi L. , Sálanki J. , Zs.‐Nagy I. , Muskó I.
Published: October 2006

Abstract— Differential and gradient centrifugation revealed that 90 per cent of the 5‐HT, dopamine and noradrenaline in the CNS of the fresh water mussel was bound to particles; 60‐70 per cent of the bound monoamines appeared in the mitochondrial and 15‐20 per cent in the microsomal fraction. Spectrofluorimetric assay and electron microscopic analysis of the subfractions obtained by separation of the mitochondrial fraction on sucrose density gradients showed that the nerve endings and their dense‐core vesicles were concentrated in fractions with high relative specific activity of the three monoamines. This supports the proposed function of these monoamines as interneuronal mediators. Osmotic shock treatment resulted in the formation of a synaptosomal subfraction of low density displaying a high relative specific activity for 5‐HT. From the results obtained one cannot draw clear‐cut conclusions regarding the participation of subcellular particles in the storage of serotonin detectable in the perikarya by means of histochemical methods.
DEVELOPMENT OF MITOCHONDRIAL PYRUVATE METABOLISM IN RAT BRAIN
Authors: Wilbur D. O. , Patel M. S.
Published: October 2006

The activities of a number of mitochondrial enzymes involved in the metabolism of pyruvate during development of the rat brain were investigated. The rates of decarboxylation of [1‐14C]pyruvate to 14CO2 via pyruvate dehydrogenase and the fixation of H14CO3− in the presence of pyruvate via pyruvate carboxylase by brain homogenates were very low in newborn rats. These rates increased markedly by about four‐fold and 15‐fold respectively during 10–35 postnatal days. The rates of the fixation of H14CO3− by cerebral homogenates were supported by the development of the activity of pyruvate carboxylase in rat brain. The activities of citrate synthase, aconitase, NAD‐malate dehydrogenase, aspartate aminotransferase, alanine aminotransferase and phosphoenol‐pyruvate carboxykinase were very low in the particulate fraction of the newborn rat brain. The activities of all these enzymes increased makedly by about three‐ to 10‐fold during 10–35 days after birth. The activity of mitochondrial phosphoenolpyruvate carboxykinase from rat brain was not precipitated by an antibody prepared against rat liver cytosolic phosphoenolpyruvate carboxykinase suggesting that cerebral mitochondrial enzyme is immunologically different from that of the cytosolic form in hepatocytes. The significance of the development of the cerebral mitochondrial metabolism is discussed in relation to biochemical maturation of the brain.
5‐HYDROXYTRYPTAMINE AND NORADRENALINE IN THE HIPPOCAMPAL REGION: EFFECT OF TRANSECTION OF AFFERENT PATHWAYS ON ENDOGENOUS LEVELS, HIGH AFFINITY UPTAKE AND SOME TRANSMITTER‐RELATED ENZYMES
Authors: Storm‐Mathisen J. , Guldberg H. C.
Published: October 2006

The monoaminergic fibres enter the hippocampal formation through a dorsal and a ventral route. The dorsal route consisting of fimbria, fornix superior and cingulum, was estimated to supply about 75% of the 5‐HT fibres and 40% of the noradrenaline containing (NA) fibres. The ventral route, allegedly passing through the amygdaloid area, accounts for the rest. The cingulum bundle contributes a definite part of the 5‐HT fibres but very few of the NA fibres. No evidence was found for an intrinsic origin of monoaminergic fibres in the hippocampal region. Monoamine oxidase and catechol‐O‐methyltransferase showed no change following the lesions and are considered to be localized predominantly outside the aminergic neurones. The results on DOPA decarboxylase indicate that about 50% of the enzyme is situated outside 5‐HT and NA nerves. Glutamic acid decarboxylase did not decrease even after transection of the ventral route, substantiating the earlier conclusion that this enzyme is situated in intrinsic neurones in the hippocampal region. For choline acetyltransferase and AChE the dorsal route was confirmed to be the only quantitatively important way of access. None of the enzymes studied, nor the uptake activities, were affected by cervical sympathectomy.
TRANSPORT OF PROTEINS, GLYCOPROTEINS AND CHOLINERGIC ENZYMES IN REGENERATING HYPOGLOSSAL NEURONS1
Authors: Frizell M. , Sjöstrand J.
Published: October 2006

The accumulation of [3H]leucine‐ and [3H]fucose‐labelled axonal proteins, acetyl‐CoA : choline O‐acetyltransferase (ChAc, EC 2.3.1.6) and acetylcholinesterase (AChE, EC 3.1.1.7) was studied proximal to a ligature applied to the hypoglossal nerve of the rabbit at different phases of nerve regeneration.

After 1 week of regeneration, the accumulation of rapidly migrating [3H]leucine‐labelled proteins, ChAc and AChE was reduced as compared to that of the contralateral nerve. In contrast, the accumulation of [3H]fucose‐labelled glycoproteins was markedly increased. After a regeneration period of 4‐6 weeks, the accumulation of proteins and glycoproteins in the regenerating nerve was increased whereas the accumulation of ChAc and AChE was almost normal.

The results indicate an initial depression of the synthesis and axonal transport of the bulk of rapidly migrating proteins, ChAc and AChE in the chromatolytic hypoglossal neurons whereas the synthesis and transport of rapidly migrating glycoproteins is increased. These initial changes are less pronounced during the subsequent regeneration period.
THE DISTRIBUTION OF AMINO ACIDS, Na+ AND K+ FROM SURFACE TO CENTRE IN INCUBATED SLICES OF MOUSE BRAIN
Authors: Sershen H. , Lajtha A.
Published: October 2006

—The effect of tissue damage on the uptake of amino acids by brain slices was investigated by measuring uptake in slices of different thickness and measuring the distribution of [14C]‐labelled amino acid on the surface and in the centre of incubated slices. The uptake of glutamate, aspartate, and GABA was greater in 0.1 mm‐thick slices than in 0.42 mm‐thick slices in short and in long (up to 120 min) incubations; the uptake of other amino acids was equal or greater in the 0.42 mm‐thick slices. The water content of incubated slices did not change greatly from surface to centre; inulin space was greater at the surface, and in slices from cortex, especially higher at the cut surface. Na+ and K+ concentrations were also higher at the surface. In the rest of the slice space, inulin, Na+ and K+ distribution was quite uniform. The distribution of ATP was inhomogeneous: in thinner slices the centre concentration was higher; in thicker slices the centre concentration was lower. Amino acid uptake initially (at 5 min) was higher at the surface, especially in the thicker slices; after longer time (30 min) incubation, the distribution of lysine and leucine was uniform, and glutamate uptake was greater at the surface. The inhomogeneity of distribution increased with increasing thickness of the slices. We concluded that the uptake of some amino acids (perhaps those for which, beside a low affinity transport, also a higher affinity transport system exists) is greater in thinner slices and greater on the surface of slices, and there is an initially inhomogeneous distribution during amino acid uptake. The uptake on the surface constitutes only a small portion of the total uptake, and tissue damage does not explain the greater uptake of amino acids by slices in comparison to the brain in vivo. This shows the higher transport capacity of cells in the brain and emphasizes the importance of mechanisms controlling the metabolite composition of the extracellular fluid in finally influencing the metabolite composition of the brain itself.
EFFECT OF UNDERNUTRITION ON AMINO ACID COMPARTMENTATION IN THE DEVELOPING RAT BRAIN
Authors: Roach Mary K. , Corbin Jannie , Pennington W.
Published: October 2006

—Rat pups undernourished through 21 days of age show abnormal patterns of cerebral amino acid metabolism. The pattern of incorporation of radioactivity from l‐[U‐14C]leucine into amino acids derived from tricarboxylic acid cycle intermediates was altered, with significantly more 14C being incorporated into glutamate and aspartate in the underfed rats than in controls. Glutamate compartmentation, manifested in the ratio of specific radioactivities of glutamine to glutamate, developed more slowly in the. diet‐restricted group. These results are similar to those seen in neonatally‐thyroidectomized rats and suggest decreased growth of neuronal processes. This impairment of amino acid metabolism returns to normal after a 7‐week period of adequate nutrition.