bluuebunny/crossref_metadata_2025 huggingface dataset:
BIOCHEMICAL EFFECTS OF THYROID DEFICIENCY ON THE DEVELOPING BRAIN
Authors: Balázs R. , Kovács S. , Teichgräber P. , Cocks W. A. , Eayrs J. T.
Published: October 2006

Abstract— The effects of neonatal thyroidectomy on some constituents of the cerebrum, cerebellum and liver of the rat have been studied during the first 7 weeks of life. In the normal rat between the 6th and 14th post‐natal days the RNA content per unit of DNA in the brain increased by 70 per cent. Although the brain continued to grow from the 14th to the 35th day, the amount of RNA relative to DNA decreased by about 20 per cent. The ratio of protein to DNA increased during the whole period studied and in the cerebral cortex it was more than trebled between the age of 6 and 35 days. The growth of the cerebellum extended over a longer period than that of the cerebrum, its weight increasing by 88 per cent between the ages of 14 and 35 days as compared with a cerebral increase of 34 per cent. The DNA content showed a 50 per cent increase during this period.

Qualitatively these maturational changes were not affected by neonatal thyroidectomy. Quantitative changes, which applied equally to the cerebral cortex and brain as a whole, were observed. At the age of 35 days, the weights of the cerebral hemispheres and cerebellum were reduced by thyroidectomy by 20 per cent; the overall DNA content per organ did not change, but the amounts of protein and RNA relative to DNA decreased significantly. It is therefore inferred that thyroid deficiency affects the size of the cells in brain and cerebellum rather than their total number. Conversely, the cell population of the liver was only a quarter of that in the control. There was a small but significant decrease in the hepatic protein and RNA content in the hypothyroid animal.

The activities of the following enzymes which served as markers for subcellular fractions in homogenates of cerebral cortex were determined: lactate dehydrogenase for the supernatant, glutamate dehydrogenase for the mitochondrial and glutamate decarboxylase for the synaptosomal fractions. When the activities were expressed on a fresh weight basis a significant decrease by comparison with the control values was observed only in the case of glutamate decarboxylase (—15 per cent at the age of 17–32 days); when the activities were based on DNA content all values were reduced, probably as a result of the general decrease in cell size.

Pyrimidine metabolism of brain and liver, studied after the administration of [6‐14C]‐orotic acid, was not affected in either tissue by neonatal thyroidectomy. A small but significant reduction in the incorporation of labelled pyrimidine nucleotides in liver RNA was observed, but no significant decrease in the incorporation in cerebral RNA was found in the hypothyroid rats.
POTASSIUM EFFECTS ON ION TRANSPORT IN BRAIN SLICES
Authors: Hertz L.
Published: October 2006

—(1) Fluxes of sodium, potassium, chloride and glutamate ions were studied in brain slices by aid of radio‐isotopes. Desaturation curves showed the efflux to occur from at least two compartments with widely different kinetics.

(2) The slowly exchanging component comprises from about 10 (sodium, potassium, chloride) to about 30 (glutamate) per cent of the radioactivity in the tissue. An energy‐requiring uptake of potassium and extrusion of sodium seems to occur in this compartment, which probably includes the nerve cells.

(3) A rather slow efflux of especially potassium ions from the rapidly exchanging fraction indicates that this component may not be purely extracellular, but also seems to include cells, which possibly are neuroglial. The hypothesis of a cellular origin is supported by the demonstration of an increase in the rate constant of the potassium efflux evoked in the presence of oxygen by high concentrations of potassium.

(4) Evidence is presented that the increase in the rate constant of the potassium efflux is due to a potassium‐induced stimulation of active transport. No coupling seems to occur between the stimulated potassium transport and movements of sodium, but potassium ions may be accompanied by glutamate ions.
ACIDIC PROTEINS IN RAT BRAIN NUCLEI: DISC ELECTROPHORESIS
Authors: Dravid A. R. , Burdman J. A.
Published: October 2006

—Disc electrophoretic patterns of soluble, acidic proteins in brain and liver nuclei and in the respective tissue homogenates were studied.

In brain nuclei, a fast component moving with the electrophoretic front constitutes a relatively large amount of the acidic proteins which migrate toward the anode. Electrophoretic patterns obtained with fractionated brain nuclei (neuronal, astrocytic and glial) were similar to those obtained with total brain nuclei. The S‐100 protein could not be detected in any of the nuclei examined.

Protein patterns in brain and liver nuclei markedly differed both quantitatively and qualitatively.
EFFECTS OF OUABAIN ON ACID‐SOLUBLE PHOSPHATES AND ELECTROLYTES OF ISOLATED CEREBRAL TISSUES IN PRESENCE OR ABSENCE OF CALCIUM
Authors: Swanson P. D.
Published: October 2006

—(1) Cerebral slices were incubated in Ca2+‐free media or in media which contained 2.8 mm‐Ca2+. Omission of Ca2+ brought about a drop in creatine phosphate content of 28 per cent, as well as a drop of 3–10 per cent in non‐inulin K+ content. There was little change in content of 10‐min phosphate or of non‐inulin Na+.

(2) Ouabain in concentrations of to M increased the loss of K+ from the slice and caused a rise in Na+ content. The changes were most marked in Ca2+‐free media. Creatine phosphate levels were depressed by ouabain both in the presence or absence of Ca2+. In the absence of Ca2+, the lowering of phosphocreatine did not occur until significant shifts in K+ had taken place. In contrast, slices incubated in Ca2+‐containing media lost creatine phosphate and K+ at about the same rate.

(3) When ouabain and labelled phosphate were added simultaneously, there was little difference in the rate of incorporation of label into creatine phosphate in media which differed in Ca2+ concentration. However, incorporation of azP‐labelled phosphate into creatine phosphate was decreased by 30–40 per cent in media which lacked Ca2+ when ouabain was added 15 min prior to the labelled phosphate. This change was not observed when the media contained Ca2+.

(4) Ouabain did not affect oxidative phosphorylation or respiratory control when added directly to bovine brain mitochondrial preparations.

(5) The results suggest that the previously observed depression of respiration brought about by ouabain in Ca2+‐deficient media is not a good indicator of the proportion of the cell's metabolism used for active cation transport. Under these conditions, the inhibition of cation transport is accompanied by a drop in slice content of high‐energy phosphate which may represent a secondary effect of ouabain, or of cytoplasmic alterations brought about by ouabain, on energy‐producing processes.
EFFECT OF TRANQUILIZERS ON REGIONAL DISTRIBUTION OF ASCORBIC ACID IN THE RAT BRAIN
Authors: Rajalakshmi R. , Patel A. J.
Published: October 2006

—Studies were made of the effects of fluphenazine, chlorpromazine and triflupromazine on tissue concentration, liver synthesis of ascorbic acid and its distribution in different areas of the brain. All the three drugs were found to increase liver concentration and synthesis of the vitamin at 24 hr after administration of a single oral dose of the vitamin, but only fluphenazine was found to increase its concentration in the adrenals and brain; the increase in the latter case was found to vary in different regions of the brain, the olfactory lobes, hypothalamus and residual brain showing maximum increases, andthe basal ganglia, visual cortex and remaining dorsal cortex showing minimum increases. The effects were found to be reversed 72 hr after drug treatment.
HOMOCARNOSINE IN HUMAN CEREBROSPINAL FLUID: AN AGE‐DEPENDENT PHENOMENON1
Authors: Perry T. L. , Hansen Shirley , Stedman Dorothy , Love Donna
Published: October 2006

—Homocarnosine, rather than carnosine, is the major imidazole dipeptide present in human CSF. This compound can be readily detected in the CSF of normal infants and young children, while it is either not detectable or is present only in very small concentrations in the CSF of normal adult subjects. Slightly greater amounts of homocarnosine can be found in the CSF of some adults with neurological disorders.
METHYLHISTAMINE IN GUINEA PIG BRAIN1
Authors: Fram D. H. , Green J. P.
Published: October 2006

Abstract—

The concentration of methylhistamine in whole brain of guinea pig is 72 ng (about 0‐5 mμ mole/g). The greatest portion is found in the crude mitochondrial fraction.
CEREBROSPINAL FLUID γ‐GLOBULINS IN SUBACUTE SCLEROSING LEUCOENCEPHALITIS
Authors: Bergmann L. , Dencker S. J. , Johansson B. G. , Svennerholm L.
Published: October 2006

Abstract— Immunoelectrophoretis, gel filtration‐electrophoresis and immuno‐gel filtration of cerebral fluid samples obtained from five patients with subacute sclerosing leucoencephalitis and known to contain an abnormal γ‐globulin fraction (γe) produced strong evidence that the γc‐globulin is made up of several components of small molecular size. This fraction is obviously not homogeneous, since some of the cases show more than one precipitate on immuno‐gel filtration with immune serum against γ‐globulin. The γc appears to be closely related to the Fab‐fragment of human γ‐globulin.
GRAMICIDIN INDUCED ION TRANSPORT IN BRAIN MITOCHONDRIA PREPARATIONS
Authors: Moore C. L.
Published: October 2006

Abstract— —(1) Gramicidin at low concentrations induces an uptake of K+ and Na+ in brain mitochondria in a manner similar to that observed with liver mitochondria.

(2) The cation uptake is energy dependent, and is accompanied by an ejection of H+ ions and a slight increase in respiration in the absence of added permeant anion.

(3) The cation uptake and hydrogen ion release are both inhibited by agents which inhibit electron transport. Barbiturates and chlorpromazine inhibit the transport phenomenon by inhibiting electron transport.

(4) In the presence of permeant anions (phosphate and acetate) respiration is stimulated quite significantly.

(5) At high gramicidin concentrations there is a release of Na+ and K+ from the mitochondria and uptake of H+. There is also a cyclic reduction‐oxidation of the nicotinamide adenine dinucleotides, which is believed to be due to the release from the mitochondria of the reduced dinucleotides followed by their subsequent oxidation.

(6) The effect of high gramicidin on the mitochondrial nicotinamide‐adenine dinucleotides and cation distribution is irreversible and is not blocked by individual inhibitors of respiration and of phosphorylation, but is prevented by prior addition of a mixture of these inhibitors.

(7) Gramicidin is therefore believed to have a bimodal function; one on the mitochondrial membrane per se, and the other on the energy dependent ion accumulation apparatus.

(8) A model of induced mitochondrial ion accumulation is presented.
FRACTIONATION OF OLFACTORY TISSUE HOMOGENATES. ISOLATION OF A CONCENTRATED PLASMA MEMBRANE FRACTION
Authors: Koch R. B. , Norring N. L.
Published: October 2006

Abstract— Differential and sucrose‐density‐gradient centrifugation techniques were used for studies on the separation of subcellular particles from rabbit brain and olfactory tissue. Comparisons were made among various fractions from the two types of tissue. These comparisons included protein concentration and enzyme activities of the individual fractions as well as their distribution in subfractions from density gradient separations.

In tissue whole homogenates, the percentage of total ATPase activity as ouabain sensitive Na+‐K+ ATPase activity was about 4 times greater in brain cortex (63 per cent) than in olfactory tissue (17 per cent). Cytochrome oxidase and Na+‐K+ ATPase activities were used to indicate the presence and the concentration of mitochondria and of the plasma membranes. A fraction with properties similar to the mitochondria plus nerve ending fraction from brain homogenates (fraction B) was obtained from olfactory tissue. Nerve ending concentration subfractions (B2) were prepared from the B primary fractions. Plasma membrane subfractions were obtained by osmotic shock treatment of B2, In the fraction of plasma membrane from olfactory tissue (E2), 56 per cent of the total ATPase activity was Na+‐K+ ATPase activity. In E2 from brain 71 per cent was Na+‐K+ ATPase activity.

Deoxycholate (DOC)‐treated fractions containing nerve endings from brain preparations showed much greater increase in cytochrome oxidase activity than did similar fractions from olfactory tissue.

DOC treatment increased the NADH cytochrome c reductase activity of all fractions and subfractions from brain, while it decreased activity in all but one fraction from olfactory tissue. DOC treatment decreased both the Mg2+ and Na+‐K+ ATPase activities in both types of tissue.

Electron photomicrographs of olfactory B2, B3, E2 and E3 show clear morphological differences among these subfractions. The presence of possible cilia and basal bodies on vesicles in B2 gives morphological evidence for the presence of terminal swellings in this subtraction in agreement with enzyme marker activity results.
THE METABOLISM OF PALMITIC ACID IN THE PHOSPHOLIPIDS, NEUTRAL GLYCERIDES AND GALACTOLIPIDS OF MOUSE BRAIN
Authors: Sun Grace Y. , Horrocks L. A.
Published: October 2006

Abstract— Following intracerebral injection, [14C]palmitic acid was rapidly incorporated into a variety of brain lipids. After 12 hr, 78 per cent of the lipid radioactivity was in phospholipids, 15 per cent was in triacylglycerols, 1 per cent each was in free fatty acids and galactolipids, and the remainder was in other neutral glycerides. Over 65 per cent of the phospholipid radioactivity was found in the choline phosphoglycerides but this proportion decreased substantially with time. At later times, increasing portions of the radioactivity were present in the monounsaturated acyl groups and the alkenyl groups but no radioactivity was detected in cholesterol or polyunsaturated acyl groups. These results indicate that most of the extensive recycling of radioactivity took place without oxidative degradation of the palmitoyl groups. The relative rates of incorporation of radioactivity were compared at 12 hr after injection. The specific radioactivities of the serine, ethanolamine, and choline phosphoglycerides had ratios of 6:3:2 based on the palmitoyl group content and 1:2:4 based on their phosphorus content. The specific radioactivities of galactolipids with O‐acyl groups were higher than the specific radioactivitiesof cerebrosides or cerebroside sulphates. A new solvent mixture for thin‐layer chromatography of brain galactolipids was described (chloroform‐acetone‐methanol‐water, 60:20:20:1, by vol.).
INFLUENCE OF AGE ON THE INCORPORATION OF [14C]GLYCINE INTO PROTEIN IN CHICKEN PERIPHERAL NERVE
Authors: Matheson D. F.
Published: October 2006

Abstract—

The conditions for incorporation of [14C]glycine in vitro into proteins in the sciatic nerve of chickens have been studied and found to be similar to those of rat nerve.

Its incorporation decreases, however, linearly with age.

The content of RNA and of DNA of peripheral nerve and the RNA/DNA ratio alter linearly with age.

There is also a linear relationship between the specific radioactivity of the protein extract and the RNA content of the nerve.

There is a linear decline with age in the specific radioactivity of the protein fraction when expressed against the DNA content.

A linear relationship exists between the logarithm of the specific radioactivity and the length of the femur.
THE UPTAKE OF METHONIUM COMPOUNDS BY ISOLATED SLICES OF RAT CEREBRAL CORTEX1
Authors: Taylor D. B. , Lu T. C. , Creese R. , Steinborn J.
Published: October 2006

Abstract— The uptakes of a series of methonium compounds, C2, C4, C6, C7, C8, C9 and C10, by isolated slices of rat cerebral cortex were measured.

Analyses of the kinetics of uptake of C7, C8, C9 and C10 indicate that their initial influxes consist of two components. A Michaelis‐Menten type uptake by carrier can account for the saturable fraction. C7 had the lowest affinity for the carrier, with values increasing for C8, C9 and C10, while C10 had the smallest maximum influx with values increasing for C9, C8 and C7. The unsaturable fraction corresponded to the slow continuous swelling of the tissue.

The uptake of C8 was inhibited by other methonium compounds, choline, ACh, physostigmine, ouabain and morphine. C8 could be counter‐transported by C7.

There is evidence that the main driving force for uptake is the transmembrane potential, but the steric factor may be a restricting influence.
LIPID COMPOSITION OF HUMAN, BOVINE AND SHEEP PINEAL GLANDS
Authors: Basinska J. , Sastry P. S. , Stancer H. C.
Published: October 2006

Abstract— —The lipid composition of human, bovine and sheep pineal glands was determined. No characteristic species difference was found in lipid content and composition. The total lipid was 2·9–4·0 per cent of wet weight of which phospholipid comprised 58–71 per cent and cholesterol 13·9–15·8 per cent in the three species. The phospholipid composition was 45 per cent phosphatidyl choline, 22 per cent phosphatidyl ethanolamine, 14 per cent sphingomyelin, 9 per cent phosphatidyl serine, 8 per cent monophosphoinositide, and 2 per cent diphosphatidyl glycerol. The major fatty acids found were C14:0, C16:0, C18:0, C16:1, and C18:1. In contrast to other tissues, pineal sphingomyelin has a low C24:1 content. No significant amounts of polyphosphoinositides or gangliosides were detected. When its lipid composition is compared with that of a number of other tissues, pineal is found to be most similar to testes and unlike pituitary and brain.
A COMPARISON OF CEREBROSIDES, PROTEOLIPID PROTEINS, AND CHOLESTEROL AS INDICES OF MYELIN IN THE ARCHITECTURE OF RAT CEREBRUM1
Authors: Bass N. H. , Hess Helen H.
Published: October 2006

Abstract— —Serial frozen section sampling and microspectrophotometric assays were used to compare the fidelity of cerebrosides, proteolipid proteins (PLP) and cholesterol as indices of myelinated fibres in the somatosensory region of rat cerebrum.

Cerebrosides (including sulphatides) were a satisfactory index regardless of the mode of expression. Per unit dry wt., they were lowest in layer II (4 per cent) and increased with the subpial depth to 16 percent in white matter. Elevations were seen at the locations of: the outer tangential plexus (1); the stripe of Kaes‐Bechterew (2); the outer and inner stripes of Baillarger (3,4); and the inner tangential plexus (5), respectively. Expression in terms of residue protein, total lipid or DNA gave somewhat sharper profiles of the myeloarchitecture.

PLP per unit dry wt. were lowest in layers I, II and III (2 per cent) and increased to 5·5 per cent in white matter. Peaks occurred near (3), (4) and (5). The PLP per cell and per unit residue protein rose six‐fold, from the upper layers of cortex to white matter, and depicted the myeloarchitecture more faithfully. In general outline, PLP paralleled cerebrosides in distribution, in contrast with previous findings in human prefrontal cortex. Human cortex may contain more non‐myelin PLP in the upper cortical layers owing to its greater wealth of neuropil and synapses.

Cholesterol per unit dry weight was a poor index of the myeloarchitecture; it was lowest in layer II (5 per cent) and increased to 13‐5 per cent in white matter without revealing the five horizontal bands of myelinated fibres. Expression of cholesterol in terms of total lipid or DNA improved its value as an index, but it was less satisfactory than cerebrosides.
AN ENZYMIC BARRIER MECHANISM FOR MONOAMINE PRECURSORS IN THE NEWLY‐FORMING BRAIN CAPILLARIES FOLLOWING ELECTROLYTIC OR MECHANICAL LESIONS
Authors: Björklund A. , Falck B. , Hromek F. , Owman Ch.
Published: October 2006

Abstract— The intracerebral capillaries of the rat constitute an enzymic trapping mechanism for certain systemically administered monoamine precursors, which are taken up into the capillary walls, decarboxylated locally to the corresponding amine and this is then metabolized by monoamine oxidase. The amine can be directly demonstrated histochemically in the endothelial cells and pericytes of the capillaries, particularly after inhibition of monoamine oxidase.

The question of whether or not these barrier properties appear also in the regenerating capillaries following electrolytic or mechanical lesions in the cerebellar parenchyma was studied after intraperitoneal injection of l‐DOPA to rats pretreated with nialamide. A very pronounced formation of new capillaries, starting at the periphery of the lesions, could be established 3–4 weeks postoperatively. Also these new, regenerating capillaries were able to trap l‐DOPA in a manner indistinguishable from that of the normal capillaries in the surrounding parenchyma. It is concluded that a complete barrier mechanism with regard to the enzymic trapping of certain monoamine precursors can reestablish after complete regeneration of the brain capillary bed in unspecific lesions.
PROTEIN SYNTHESIS IN THE MEDULLA OF THE RAT BRAIN. REPRODUCIBILITY OF THE RESULTS
Authors: Foulkes J. A. , Robinson N.
Published: October 2006

Abstract— [14C]Leucine was injected intracranially into the brainstem reticular formation at the level of the upper medulla by the stereotaxic method. Subcellular fractions prepared 3 hr after injection showed that the specific activities of leucine‐incorporated proteins decreased in the order soluble, microsomal, nuclear and mitochondrial fractions. Specific activities of proteins in the sera were 2·2 per cent of whole homogenate proteins.

The results from 27 experiments showed that 66·6 per cent of the mean specific activities of proteins extracted from whole homogenates fell within ·1 s.d. and 100 per cent within ± 2 s.d. (close to a normal distribution). The coefficients of variation were between 40 and 50 per cent for whole homogenates, sera and all subcellular fractions. Reproducibility of results and factors concerned with possible errors in the technique are discussed.
ACETYLCHOLINE AS A TRANSMITTER IN THE CAT AUDITORY SYSTEM1
Authors: Comis S. D. , Davies W. Ewart
Published: October 2006

Abstract— The ACh content of the cat cochlear nucleus was determined following intraventricular injection of hemicholinium. The data presented shows that the level of ACh can be greatly reduced by stimulation of a centrifugal pathway arising from the ipsilateral superior olive. Additional data is provided by a single neurone study which shows that this stimulation also blocks the normal physiological effects of the pathway. This evidence supports the hypothesis that ACh is a transmitter in a centrifugal pathway within the cat auditory system.
EFFECTS OF DURATION OF CONVULSIONS ON ENERGY RESERVES OF THE BRAIN1
Authors: King Lucy J , Webb O. Lynn , Carl Juanita
Published: October 2006

Abstract— Rapid administration (0·4 ml in 1 sec) of the convulsant inhalant, flurothyl (hexafluorodiethyl ether, indoklon), to mice induced within 10 sec clonic‐tonic seizures that were accompanied by marked decrease of P‐creatine, decrease of ATP and glucose, and increase of lactate in the cerebral cortex. In contrast, mice to which flurothyl had been administered slowly (0·05 ml every 30 sec for 10 min) exhibited myoclonic jerks after about 3 min, merging into irregular clonus at about 5 min, and intermittent clonus thereafter until onset of tonic hind limb extension at about 10 min. In these mice, P‐creatine in cerebral cortex decreased gradually for 6 min and then remained through 10 min at levels nearly as low as those reached 10 sec after rapidly administered flurothyl. Lactate in cerebral cortex increased much more during the 10 min of slow administration of flurothyl than in 10 sec of rapid administration, the greatest increase occurring at 4–6 min, as myoclonic jerks merged into irregular clonus. Glucose and ATP in cerebral cortex fluctuated somewhat but did not decrease greatly when flurothyl was administered slowly.
THE PRESENCE OF AN α‐GALACTOSIDASE IN BRAIN AND ITS ROLE IN THE DEGRADATION OF THE DIGALACTOSYL DIGLYCERIDE OF BRAIN
Authors: Rao K. Subba , Pieringer R. A
Published: October 2006

Abstract— The presence of α‐galactosidase activity has been demonstrated in rat brain. This enzyme, located mainly in the crude mitochondrial fraction, actively hydrolysed the substrates p‐nitrophenyl‐α‐galactoside and melibiose, and also catalysed the hydrolysis of digalactosyl diglyceride of both animal and plant origin. The hydrolysis of p‐nitrophenyl‐α‐galactoside, as catalysed by the α‐galactosidase, occurred optimally at pH 4·9, showed an approximate Km of 1·0 × 10−3m, and was markedly inhibited by melibiose, galactose and the mercuric ion.
UNTERSUCHUNGEN DES GLUTAMATSTOFFWECHSELS IN VERSCHIEDENEN HIRNAREALEN DES HUNDES IM PRÄKONVULSIVEN ZUSTAND METABOLIC INVESTIGATIONS OF EPILEPTIC SEIZURES Investigations of Glutamate Metabolism in Regions of the Dog Brain in Preconvulsive States
Authors: Wiechert und P. , Gölnitz G.
Published: October 2006

Zusammenfassung —Die Aktivitäten der Glutamat‐Decarboxylase, Glutamat‐Oxalacetat‐Transaminase, Glutamat‐Pyruvat‐Transaminase, Glutamat‐Dehydrogenase und Glutamin‐synthetase sowie die Konzentration der freien Aminosäuren und des Ammoniaks wurden in neun Hirnregionen des Hundes (Amygdalae, Thalamus, Nucleus caudatus, Hippocampus, Temporalpol, Gyrus cinguli, Kleinhirnmark, Kleinhirnrinde, Medulla oblongata) in der präkonvulsiven Phase nach intracisternaler Injektion von l‐Glutamat bzw. Pyridoxal‐5‐phosphat bestimmt.

Sechs der neun untersuchten Gebiete zeigten keine auffälligen Stoffwechselveränderungen. Lediglich im Amygdalae, Hippocampus und in der Medulla oblongata konnten deutliche Unterschiede verschiedener Enzymaktivitäten und Substratkonzentrationen beobachtet werden. Die Erhöhung des Glutamats im Hippocampus erscheint wegen der Übereinstimmung mit den an den Rattengehirnen gefundenen Veränderungen am wichtigsten und wird als möglicher Ausgangspunkt für einen cerebralen Anfall diskutiert.

Abstract —The activities of glutamate decarboxylase, aspartate aminotransferase (glutamic‐oxalacetic transaminase), EC 2.6.1.1 alanine aminotransferase (glutamic‐pyruvic transaminase EC 2.6.1.2), glutamate dehydrogenase and glutamine synthetase, as well as the concentration of free amino acids and ammonium were determined in nine regions of the dog brain (nucleus amygdalae, thalamus, nucleus caudatus, hippocampus, temporal lobe, gyrus cinguli, cerebellar marrow, cerebellar cortex, medulla oblongata) in the preconvulsive phase after injections of l‐glutamate and pyridoxal‐5‐phosphate.

In six of the nine regions examined there were no considerable metabolic changes. Marked changes in different enzyme activities and substrate concentrations were observed in the nucleus amygdalae, hippocampus and medulla oblongata. The increase of glutamate in the hippocampus seems to be of great importance in view of the agreement with alterations found in the brains of rats, and this is regarded as a starting point for cerebral seizures.
FORMATION AND TURNOVER OF MYELIN GANGLIOSIDE*
Authors: Suzuki Kunihiko
Published: October 2006

—In young adult rats, the formation and turnover of GM1‐ganglioside in myelin were compared with the formation and turnover of GM1‐ganglioside in whole brain and of total lipids in whole brain and myelin, after injection of d‐[1‐14C]glucosamine. During the first 24 hr after injection, the specific activity of GM1‐ganglioside in myelin was less than 25 per cent of that of GM1‐ganglioside in whole brain. The specific activity of ganglioside in whole brain was maximal at 24 hr and then declined steadily during the next 3 months, whereas the specific activity of GM1‐ganglioside in myelin continued to increase and did not reach a peak until about one month after injection, by which time its specific activity had increased five‐fold. Consequently, the specific activity of GM1‐ganglioside in myelin was 50 per cent higher than ganglioside in whole brain after one month. These differences in the formation and turnover of GM1‐ganglioside in myelin and of whole brain are similar to those of other lipids of myelin and of whole brain, indicating that the metabolic activity of myelin ganglioside is similar to myelin lipids, but differs from whole brain lipids or whole brain gangliosides. These data provide additional evidence that ganglioside in myelin is an intrinsic constituent of the myelin sheath. GT1 (G1), GD1b, (G2), GD1a (G3), GM1 (G4), GM2 (G5), GM3 (G6).
APPEARANCE OF A BRAIN SPECIFIC ANTIGEN (THE S‐100 PROTEIN) DURING HUMAN FOETAL DEVELOPMENT1
Authors: Zuckerman J. E. , Herschman H. R. , Levine L.
Published: October 2006

—The concentration of a protein specific to brain, the S‐100 protein, was measured in various regions of the human foetal brain at gestational ages ranging from 10 weeks until term. The relative increase in concentrations of the S‐100 protein during development of the human foetal brain proceeded in a caudal‐rostral fashion. This observation is emphasized by the delayed appearance of the S‐100 protein in the frontal cerebral cortex until the 30th week of gestation.
SELECTIVE RETENTION OF OESTRADIOL BY CELL NUCLEI IN SPECIFIC BRAIN REGIONS OF THE OVARIECTOMIZED RAT1
Authors: Zigmond R. E. , McEwen B. S.
Published: October 2006

—Cell nuclei were isolated from four regions of the brains of ovariectomized female rats 2 hr after the injection of [3H]oestradiol. By light microscopy, the nuclear pellets contained highly purified nuclei of neuronal and glial cells with little cytoplasmic contamination. Tritium was concentrated in cell nuclei from the preoptic‐hypothalamic area, to a lesser extent in nuclei from the amygdaloid region and hippocampus, and least of all in cerebral cortical nuclei. In comparison with whole homogenates (= 1‐0), the nuclear concentrations of radioactivity were 12·9, 4·7, 1·9 and 0·8, respectively. Approximately 40 per cent of the radioactivity in homogenates of the preoptic‐hypothalamic area was present in cell nuclei, and upon TLC more than 85 per cent of the radioactive material in the nuclei exhibited the RF of oestradiol‐17β.

Pretreatment of ovariectomized females with 1 mg of unlabelled oestradiol 30 min before the injection of labelled hormone abolished the nuclear uptake of [3H]oestradiol in all four regions of the brain. A concurrent injection of 10 μg of unlabelled oestradiol‐17β significantly reduced nuclear uptake, while a similar injection of testosterone or oestradiol‐17α had no significant effect. One mg of oestradiol‐17α, but not testosterone, did reduce nuclear uptake.

The retention of [3H]oestradiol by the preoptic‐hypothalamic area decreased exponentially in the tissue from 30 min to 4 h after an intraperitoneal injection; however, nuclear binding reached a peak at 1‐2 h and still showed high retention at 4 h. These results, together with observations in other laboratories of morphological changes induced by oestrogens, establish that certain regions of the brain are bona fide targets for the action of oestradiol.
INHIBITION OF ACETYLCHOLINESTERASE IN VITRO BY PENTYLENETETRAZOL1
Authors: Mahon P. J. , Brink J. J.
Published: October 2006

Abstract—The effect of pentylenetetrazol (PTZ) on acetylcholinesterase (E.C.3.1.1.7) was studied in vitro. The kinetics of the reaction were studied on AChE in crude homogenates of rat brain and in purified preparations from Electrophorus electricus. The Km for rat brain AChE was 1·22 × 10‐4m, with a Vmax of 1·37 μmol/g/min whereas the K4 for competitive inhibition of the enzyme by PTZ was 4·7 × 10‐3m. The commercially purified enzyme exhibited a Km of 1·73 × 10‐4m and a Ki of 1·00 × 10‐3m.
CALCIUM CONTENT AND EXCHANGE IN NEOCORTICAL TISSUES DURING THE CATION MOVEMENTS INDUCED BY GLUTAMATES
Authors: Ramsey R. L. , McIlwain H.
Published: October 2006

Abstract—

Guinea pig neocortical tissues incubated in glucose‐bicarbonate media reached stable calcium contents of 2 μat./g of which 0‐35 μat.Ca/g was in a space accessible to inulin.

Addition of l‐glutamate salts caused a prompt increase in intracellular calcium at rates up to 7 μat./g tissue/hr.

Using 45Ca, this increase was found to be due to an accelerated influx of Ca and a diminished efflux. The rate of influx could be doubled by 1 mm‐l‐glutamate.

Tetrodotoxin at concentrations of 66‐330 nM diminished 45Ca entry, both in the absence and presence of added glutamate.

Tissue sodium and potassium contents are also reported under some conditions, and the extent to which calcium may condition sodium and potassium movements is discussed.
FORMATION OF ASPARAGINE FROM ASPARTIC ACID IN RAT BRAIN
Authors: Benuck M. , Stern F. , Lajtha A.
Published: October 2006

Abstract—

The synthesis of asparagine in rat brain was studied both in vitro and in vivo. A conversion in vitro of about 2 per cent of the added l‐[14C]aspartic acid into asparagine was found after a 2 h incubation with the 100,000 g supernatant fraction from brain. This corresponded to a formation of 4·8 nmol of asparagine/mg of protein/h. The reaction required ATP and glutamine, and was linear with time during the 2 h incubation. When the crude mitochondrial fraction was added to the incubation mixture the reaction was inhibited, probably because of the presence of ATPase activity in the mitochondrial preparation. Inhibition by the reaction product seemed unlikely since removal of endogenous asparagine did not stimulate the reaction; only when asparagine was added at levels of 0·5 or 1·0 mm was significant inhibition found. Ammonium chloride was less effective than glutamine as an amide donor. Endogenous asparaginase (EC 3.5.1.1.) activity was low in the in vitro preparation and did not significantly affect the conversion. Synthesis of asparagine from aspartic acid did not occur in slices of brain nor was there a significant conversion of aspartic acid or glucose to asparagine after their intracerebral administration in vivo.
CHOLINE ACETYLTRANSFERASE IN INDIVIDUAL NEURONS OF APLYSIA CALIFORNICA1
Authors: McCaman R. E. , Dewhurst Susan A.
Published: October 2006

Abstract—

The activities of choline acetyltransferase in the various ganglia of the nervous system of Aplysia californica and in some of the individually identifiable neurons in these ganglia were measured. At least four of the neurons were characterized by an apparent absence of the enzyme. The neurons containing measurable amounts of the enzyme had reproducible levels from animal to animal. Individual neurons from the same animal were generally characterized by different levels of activity whether expressed on a cell or a protein basis. However, those pairs of neurons previously classified as ‘homologous’ because of their similar appearance, location and/or electrophysiological function, also contained the same total amounts of enzyme activity.
INCREASED INCORPORATION OF [G‐3H]LEUCINE INTO A POSSIBLE ‘RECEPTOR’ PROTEOLIPID IN DENERVATED MUSCLE IN VIVO
Authors: Lunt G. G. , Stefani E. , Robertis E. De
Published: October 2006

Abstract—The incorporation of radioactive leucine into the total proteins and the proteolipids of normal and denervated rat diaphragm has been studiedin vivo.Denervation increased the incorporation of isotopically labelled leucine into each of the isolated proteolipids and the effect was particularly marked in a single proteolipid which has been designated a ‘receptor’ proteolipid. In normal muscle this particular proteolipid was found to have a higher incorporation of isotopically labelled leucine in the area of the muscle rich in endplates compared with an area devoid of endplates. However the stimulatory effect of denervation on the incorporation of radioactive leucine into this proteolipid was considerably more marked in the latter region. An attempt has been made to correlate these findings with the development of the hypersensitivity to ACh characteristic of denervated muscle.
STUDIES ON THE TURNOVER OF MOUSE BRAIN SYNAPTOSOMAL PROTEINS1
Authors: Morris S. J. , Ralston H. J. , Shooter E. M.
Published: October 2006

Abstract—

(l) The half‐lives of the proteins of various fractions of whole mouse brain increase with increasing insolubility; the supernatant and hypotonic‐extractable proteins had half‐lives of about 13 days, whereas the membrane proteins solubilized with Triton X‐100 and SLS had half‐lives of about 18 days. The proteins of the subfractions of synaptosomes had half‐lives ranging from 15 to 19 days; those in the cytoplasm had a half‐life of 18·3 days, in the membranes, about 17 days and in the synaptic vesicles, 15·6 days.

(2) Although the half‐life of the synaptic vesicles was not significantly different from that of other synaptosomal subfractions, the vesicles exhibited a different protein pattern on acrylamide gels, an observation which implies that the proteins of the vesicles are qualitatively different from those of other synaptic membranes.

(3) The uptake of labelled lysine into the cytoplasm of the synaptosomes of youg mice in vivo was very rapid.

(4) The data derived from the relative specific radioactivities of synaptosomal fractions compared with their whole brain analogs support the contention that a sizeable fraction of the synaptosomal cytoplasmic protein was transported to the synapse by axoplasmic flow. The relative specific radioactivities of synaptosomal membrane and synaptic vesicle proteins rose much more quickly than the comparable activities for the cytoplasmic material, and the alternate possibility of synthesis in situ is discussed.
ENZYME ALTERATIONS AND LIPID STORAGE IN THREE VARIANTS OF TAY‐SACHS DISEASE
Authors: Sandhoff K. , Harzer K. , Wässle W. , Jatzkewitz H.
Published: October 2006

Abstract—

In autopsy tissues of 12 cases of Tay‐Sachs disease the N‐acetyl‐β‐hexosamini‐dase A and B activities were investigated using chromogenic and physiological substrates.

In three cases of Tay‐Sachs disease, classified as the variant O, the enzyme activities A and B were missing; in eight cases, classified as the variant B, the enzyme activity A was missing. In another case, both enzyme activities wcre shown to be enhanced in brain tissue (‘variant AB’), using a chromogenic substrate.

The three enzymic variants showed different glycolipid storage patterns of Tay‐Sachs‐ganglioside (TSG) and its asialo residue, the trihexosylceramide (THC) in the nervous tissues. Additional storage of kidney globosidc was found in the visceral tissues of the O variant. A decrease of the non‐accumulated lipids, especially of those characteristic for myelin, was observed. The quantitative lipid determinations were performed by means of a thin‐layer densitometric micromethod (standard deviation 2–5 per cent).

Evidence is presented that the different storage patterns result from the corresponding enzyme alterations in the three variants. An essential condition for this statement was the isolation of the storage compounds from Tay‐Sachs tissues and their radioactive labelling by the addition of tritium to the double bond in their sphingosine moiety. In a previous investigation it was shown that enzyme A degrades the storage compounds TSG, THC and kidney globoside while enzyme B acts on THC and kidney globoside only. In agreement with this finding, a highly concentrated mixture of both enzymes from normal tissues hydrolyses the main storage compound, the Tay‐Sachs‐ganglioside. This hydrolysis was reduced when corresponding enzyme preparations from tissues of variants of Tay‐Sachs disease (including variant AB) acted on TaySachs ganglioside.

Some properties of the N‐acetyl‐β‐D‐hexosaminidases from normal and from pathological tissues were determined with chromogenic and physiological substrates. The relationship between the enzymes A and B is discussed.
ON ARABINOSE AS A CONSTITUENT OF HYALURONIC ACID FROM BOVINE BRAIN
Authors: Katzman R. L.
Published: October 2006

(1) Wardi, Allen, Turner and Stary (1966) and Margolis (1967) have reported that arabinose is a component of hyaluronic acid from mammalian brain.

(2) In the present study, total acidic polysaccharide and hyaluronic acid fractions were isolated from lipid‐extracted and proteolysed bovine brain by precipitation with cetyltri‐methylammonium bromide. These fractions were analysed for arabinose by paper chromatography of deionized hydrolysates and by gas‐liquid chromatography of per(trimethylsilyl)ated methanolysates.

(3) Two pentoses, xylose and ribose, were detected. Arabinose was analytically undetectable in both polysaccharide fractions, but was easily detected in a control polysaccharide containing 0‐1% (w/w) arabinose. Arabinose, if present in hyaluronic acid from bovine brain, constitutes less than 0.1 mol per mol of hyaluronic acid (molecular weight 1.5 x 106 daltons).
DNA AND RNA AND THE CYTOARCHITECTURE OF HUMAN FRONTAL CORTEX1
Authors: Hess Helen H. , Thalheimer Caroline
Published: October 2006

DNA and RNA were studied in the layers of human prefrontal cortex by quantitative microchemical analyses on microtome‐prepared serial frozen sections. Eleven cortical specimens from six autopsy brains were assayed. The mean total number of cells per mm3 of fresh cortex was estimated from DNA values. The number in layer I (61,000) was falsely high because of the inclusion of cells from the pia mater. From a plateau of 82,000‐86,000 in layers II, IIIa and IIIb, the number of cells rose to 91,000 and 113,000 in layers IIIc and IV, respectively. The mean number was slightly lower in layer V, then gradually rose through layer VI to 127,000 cells in white matter. Per unit dry weight, DNA and cells varied much less than per unit volume; values averaged 14 per cent higher in layers II and IV than in neighbouring layers and in white matter were 20 per cent lower than in layer I.

Intracortical patterns of RNA and RNA/cell reflected chiefly the distribution of neuronal cell bodies. Per unit fresh volume, RNA roughly paralleled DNA in layers I‐V; through layer VI and into white matter RNA declined as DNA rose, reflecting the decline in neurons and increasing predominance of glial cells of lower RNA content. Per unit dry weight, RNA rose 50 per cent from layer I to layer II; a plateau of high values extended through layers II‐V, then RNA declined rapidly through layer VI to a level in white matter that was 28 per cent of the value in layer II. Mean RNA/cell in cortex was 9‐8 pg, with a maximum in layer IIIb (11.4 pg); in subcortical white matter it was 5.3 pg.
CEREBRAL PHOSPHOLIPIDS IN ‘QUAKING’ MICE
Authors: Dawson R. M. C. , Clarke N.
Published: October 2006

The brain of the adult ‘quaking’ mutant mouse is characterized by a reduced phospholipid content which can be ascribed not only to the myelin deficiency but also to a well‐defined hydrocephalus. The mutant brain shows highly significant decreases in the percentage of ethanolamine plasmalogen, triphosphoinositide and phosphatidic acid in the whole phospholipid fraction, while the proportions of phosphatidylcholine, phosphatidyl‐ethanolamine, diphosphatidylglycerol and phosphatidylinositol increase. The changes are consistent with the selective absence of ‘myelinic’ phospholipid although phosphatidylserine, sphingomyelin and diphosphoinositide are unchanged.
PARTIAL CHARACTERIZATION OF SOLUBLE ACETYLCHOLINESTERASE ISOENZYMES OF THE RAT BRAIN
Authors: Bajgar J. , ŽIžkovský V.
Published: October 2006

(1) The 105,000gsupernatant fluid obtained from rat brain was separated by agar‐gel electrophoresis.

(2) Three isoenzymes, capable of hydrolysing acetylthiocholine, one of them also hydrolysing butyrylthiocholine, were detected.

(3) The pH optima andKmfor hydrolysis of acetyl‐ and butyrylthiocholine by the supernatant fluid were determined.

(4) After extraction of acetylcholinesterase isoenzymes from the gel, individual isoenzymes were characterized by pH optima andKmvalues.

(5) Two of the enzymes were characterized as acetylcholinesterase (EC 3.1.1.7) and one as butyrylcholinesterase (EC 3.1.1.8).
EFFECTS OF AMINES ON THE LEVEL OF N‐ACETYL‐ASPARTATE AND N‐ACETYL‐ ASPARTYL‐GLUTAMATE IN MOUSE BRAIN TISSUE SLICES
Authors: Reichelt K. L. , Wedege E. , Kvamme E.
Published: October 2006

The effect of some biogenic amines and amino acids on the level of N‐acetyl‐asparticacid and N‐acetyl‐aspartyl‐glutamic acid has been investigated in mouse brain tissue slices. The amines all caused a significant decrease in the levels of N‐acetyl‐aspartic acid and N‐acetytl‐aspartyl‐glutamic acid within 5 min of incubation, while the amino acids, in spite of being possible transmitter candidates, had no such effect.
THE PREVENTION BY INHIBITORS OF BRAIN PROTEIN SYNTHESIS OF THE HYPERACTIVITY AND HYPERPYREXIA PRODUCED IN RATS BY MONOAMINE OXIDASE INHIBITION AND THE ADMINISTRATION OF L‐TRYPTOPHAN OR 5‐METHOXY‐N,N‐DIMETHYLTRYPTAMINE
Authors: Grahame‐Smitha D. G.
Published: October 2006

Abstract— In rats treated with a monoamine oxidase inhibitor, (tranylcypromine), L‐ tryptophan produces a stereotyped syndrome of hyperactivity and hyperpyrexia due to an increased rate of brain serotonin (5‐hydroxytryptamine) synthesis. Pretreatment of rats with intraperitoneal injections of cycloheximide, acetoxycycloheximide, emetine and dehydroemetine and of mice with puromycin inhibited this syndrome. Cycloheximide also inhibited the hyperactivity caused by tranylcypromine and DL‐15‐hydroxtryptophan and did not affect the increased rate of brain serotonin ‘synthes’ is produced by tryptophan thus excluding a primary effect on tryptophan‐5‐hydroxylase. Inhibition of hyperactivity did not occur until brain protein synthesis was inhibited by greater than 65 per cent as measured by the incorporation of L‐[U‐14C]tyrosine into brain protein in vivo. Emetine, which has been shown to inhibit brain protein synthesis inhibited hyperactivity whereas isoemetine which did not inhibit brain protein synthesis, did not inhibit hyperactivity.

Under conditions where cycloheximide inhibited hyperactivity produced by tranylcypromine and L‐tryptophan, a large dose of 5‐methoxy‐N,N‐dimethyltryptamine(5‐MeODMT) still produced hyperactivity showing that the rats were still capable of the same pattern of hyperactivity. However, cycloheximide did inhibit hyperactivity due to 5‐MeODMT, the degree of this inhibition being dependent upon a balance between the doses of cycloheximide and 5‐MeODMT. 5‐MeODMT probably acts directly within the brain to cause behavioural excitation and it seems likely that the inhibitors of brain protein synthesis interfere with the mechanism of action of brain 5HT and administered 5‐MeODMT rather than upon any aspect of synthesis, storage or release of brain 5HT. It is suggested that the behaviourally excitant effects of brain 5HT and 5‐MeODMT are mediated in some way by a brain protein with a short biological half‐life. Such a protein may act either as a factor specifically mediating the central effects of brain 5HT or as a factor regulating the neuronal response to excitation by 5HT and 5‐MeODMT.