bluuebunny/crossref_metadata_2025_split huggingface dataset:
LEUCINE TRANSPORT FROM THE VENTRICLES AND THE CRANIAL SUBARACHNOID SPACE IN THE CAT1
Authors: Lorenzo A. V. , Snodgrass S. R. 
Published: October 2006

Abstract— The clearance of [14C]leucine from the ventricular and cranial subarachnoid space was studied in cats subjected to ventriculo‐cisternal and ventriculo‐craniosubarachnoidal perfusions. Clearance from both the ventricles and the subarachnoid space was mediated by transport mechanisms with nonsaturable and saturable components. Net clearance from the subarachnoid space was considerably greater than from the ventricles. Analysis of the transport kinetics revealed the affinity constants (Kt) to be comparable for both compartments but transport sites appeared to be more numerous in the subarachnoid space (greater Vmax).Proportionally, the amount of [14C]leucine retained by brain declined as the concentration of leucine in the perfusate was increased. Since at high concentrations the CSF transport systems and presumably cellular uptake were inhibited (self‐saturated) it was assumed that the lower brain levels of [14C]leucine reflected a proportionately greater loss of [14C]‐leucine from the brain interstitial space to blood.
EFFECTS OF CORTICOSTEROIDS ON THE BIOCHEMICAL MATURATION OF RAT BRAIN: POSTNATAL CELL FORMATION
Authors: Cotterrell Mary , Balaazs R. , Johnson A. L. 
Published: October 2006

Abstract(1) Treatment with cortisol acetate (0.2 mg daily during the first 4 days after birth) reduced the rate of growth in the rat: at 35 days of age the body weight was reduced by 50 per cent and the brain weight, depending on the region, by up to 30 per cent.(2) In the brain the normal increase in cell number was severely inhibited during the period of cortisol treatment; this resulted in a final deficit in cell number of about 20 per cent in the cerebrum and 30 per cent in the cerebellum.(3) To determine whether cortisol affected primarily cell formation or cell destruction the labelling of brain DNA was studied 1 h after a subcutaneous injection of 20 Ci/100 g [2‐14C]thymidine. In the controls the amount of labelled DNA increased by a factor of two in the cerebrum and seven in the cerebellum during the period 2‐13 days, and it decreased to 40 and 27 per cent of the peak values in the cerebrum and cerebellum respectively in the following 7 days. The results indicated that mitotic activity is higher in the cerebellum than in the cerebrum in the 2nd week of life. It would appear that in the cerebrum appreciable cell death accompanies new cell formation, especially during the period 13‐35 days of age.(4) Cortisol treatment affected cell division rather than cell destruction in the brain since it strongly inhibited the incorporation of [2‐14C]thymidine into DNA. The inhibition was severe during the period of treatment but it did not result in a lasting fall in mitotic activity. At the age of 13 days the amount of labelled DNA formed approached the normal level and it was twice that in controls at 20 days, indicating a tendency for compensating cell deficit by an accelerated mitotic activity. Nevertheless, massive cell proliferation ceased at about the same age as in normals; the labelling of DNA decreased markedly between 13 and 20 days after birth, and the DNA content did not increase after the age of 20 days.(5) In contrast to the marked effect on cell number, cortisol treatment did not influence significantly the maturational changes related to average cell size (DNA concentration) or the chemical composition of cells (RNA/DNA and protein/DNA).
ON THE MECHANISM OF THE NULLIFICATION OF CNS EFFECTS OF l‐DOPA BY PYRIDOXINE IN PARKINSONIAN PATIENTS1
Authors: Pfeiffer R. , Ebadi M. 
Published: October 2006

AbstractAdministration of either Levodopa (l‐DOPA) or pyridoxine increased the concentration of dopamine in the basal ganglia of rats. However, administration of pyridoxine to rats pretreated with l‐DOPA for several days resulted in a reversal of the l‐DOPA‐induced elevation of dopamine. Pretreatment of rats with Ro 4‐4602 (an inhibitor of peripheral aromatic amino acid decarboxylases) enhanced the l‐DOPA‐induced rise in the CNS level of dopamine. This effect was also reduced substantially after the administration of pyridoxine. We interpret these results to indicate that the antagonistic effect of pyridoxine on the beneficial effects of l‐DOPA in the CNS is centrally mediated as a result of decreased formation of dopamine.
EVIDENCE FOR DEGENERATION OF SYMPATHETIC NERVE TERMINALS CAUSED BY THE ORTHO‐ AND PARA‐QUINONES OF 6‐HYDROXYDOPAMINE
Authors: Heikkila R. E. , Mytilineou C. , Cócté L. , Cohen G. 
Published: October 2006

Abstract6‐Hydroxydopamine and its corresponding ortho‐ and para‐quinones were injected intraperitoneally into male Swiss‐Webster mice. Measurements made 72 h after injection showed that all three compounds caused a decrease in the uptake of [3H]norepinephrine into slices of mouse heart tissue in vitro, a decrease in the endogenous content of heart norepine‐phrine, and a disappearance of the adrenergic nerve plexus of the mouse iris as viewed by fluorescence histochemistry. These data suggest that both the ortho‐ and para‐quinones of 6‐hydroxydopamine are capable of producing a chemical sympathectomy similar to that caused by 6‐hydroxydopamine.
THE EFFECT OF l‐3,4‐DIHYDROXYPHENYLALANINE ADMINISTRATION ON GLUCOSE METABOLISM IN BRAIN1
Authors: Tyce Gertrude M. , Owen C. A. 
Published: October 2006

AbstractThe effect of the administration of l‐3,4‐dihydroxyphenylalanine (l‐DOPA) on the metabolism of glucose in brain was studied by administering [U‐14C]glucose to three groups of rats: (1) those injected previously with l‐DOPA, 100 mg/kg; (2) those fed 1 % (w/w) l‐DOPA in their diet for several months and also injected 15 min before the administration of glucose with l‐DOPA, 100 mg/kg; and (3) appropriate controls. Chronic treatment with l‐DOPA caused a decrease in the flux of carbon from glucose in plasma to those amino acids in brain that are in equilibrium with the tricarboxylic acid cycle intermediates but not to lactate and alanine. Similar differences from controls, but of smaller magnitude, were observed in rats given a single injection of l‐DOPA. Concentrations of glucose in plasma and in brain were increased after acute or chronic treatment with l‐DOPA. A single injection of l‐DOPA did not cause changes in the levels of the most abundant amino acids in brain, but after chronic treatment with l‐DOPA modest changes were noted in the brain levels of some ninhydrin‐reacting substances; the contents of taurine and aspartate were lower and those of threonine, serine, glutamine, and glycine were higher.
STUDIES ON RNA SYNTHESIS IN TWO POPULATIONS OF NUCLEI FROM THE MAMMALIAN CEREBRAL CORTEX
Authors: THOMPSON R. J. 
Published: October 2006

AbstractA method is presented for the rapid separation of cell nuclei from the rabbit cerebral cortex into two populations. The first of these consists largely of nuclei with the morphological characteristics of neuronal nuclei, the second almost entirely of nuclei with the morphological characteristics of glial cell nuclei. From studies based upon sensitivity to the toxin α‐amanitin, the ratio of incorporation of different bases, ionic requirements and differential sensitivity to actinomycin D, it is concluded that under both the classical low and high salt conditions described by other workers, two enzymes are active in RNA synthesis. The presence of a third enzyme of low activity cannot be excluded. No qualitative difference in the number of enzymes involved in RNA synthesis in neuronal and glial cell nuclei has been found, but there are quantitative differences in activity between the two nuclear populations.
SOME ENZYMIC ASPECTS OF THE PRODUCTION OF OXIDIZED OR REDUCED METABOLITES OF CATECHOLAMINES AND 5‐HYDROXYTRYPTAMINE BY BRAIN TISSUES
Authors: Duncan R. J. S. , Sourkes T. L. 
Published: October 2006

AbstractThe Michaelis constants of purified aldehyde dehydrogenase (aldehyde: NAD oxidoreductase, EC 1.2.1.3) and aldehyde reductases (alcohol: NADP oxidoreductase, EC 1.1.1.2) from pig brain have been obtained for a number of biologically important aldehydes. The aldehydes include 3,4‐dihydroxyphenylacetaldehyde, D‐3,4‐dihydroxyphenylglycolaldehyde, and 5‐hydroxyindoleacetaldehyde. The relative activities of the aldehyde‐catabolizing enzymes in the soluble fractions of the cerebral cortex and caudate nucleus of pig brain have also been obtained. The values are used to show that the metabolic fates of the various aldehydes—and hence of the parent amines—may be explained in terms of the simple kinetics of these enzymes. It is also shown that the metabolic fates of the aldehydes may be influenced by their rates of synthesis. As the rate of aldehyde production increases the proportion of aldehyde reduced may be expected to increase at the expense of the proportion of aldehyde oxidized.It is further concluded from the kinetic constants that selective inhibition of aldehyde dehydrogenase may greatly affect the catabolism of dopamine and 5‐hydroxytryptamine by altering the relevant aldehyde concentrations, while the catabolism of norepinephrine is little affected under these circumstances. Conversely, it is concluded that selective inhibition of the aldehyde reductases should scarcely affect the catabolism of dopamine and 5‐hydroxytryptamine, but that the catabolism of norepinephrine should be markedly affected.The results also indicate that the concentrations of the various deaminated metabolites of the biogenic amines could be selectively controlled by modulation of the activity of the enzymes of aldehyde catabolism in brain.
ALTERATIONS IN CYCLIC AMP METABOLISM ASSOCIATED WITH PHOTORECEPTOR CELL DEGENERATION IN THE C3H MOUSE1
Authors: Lolley R. N. , Schmidt Susan Y. , Farber Debora B. 
Published: October 2006

AbstractPrevious studies have shown an abnormality in cyclic nucleotide phosphodiesterase activity in the retina of mice (C3H/HeJ) with an inherited degeneration of the photoreceptor layer. Adenyl cyclase activity and cyclic AMP content have been measured in C3H retina and compared with that in normal retina (DBA/1J) during postnatal maturation, to assess the influence of the mutation upon cyclic AMP metabolism. Adenyl cyclase activity increases normally for the first 7 days of age; thereafter, it becomes greater than normal. Cyclic AMP becomes obviously abnormal after 10 days of age. The elevated levels of cyclic AMP persist in the surviving cells of the inner layers of the adult C3H retina. Adenyl cyclase activity and cyclic AMP content are concentrated in the inner layers of the normal retina, while the photoreceptor layer has only a very low level of enzyme activity and cyclic AMP. The data suggest that the synthesis of cyclic AMP in the inner layers of C3H retina is significantly enhanced, during the period of postnatal development in which the photoreceptor cells have begun to degenerate.
CHANGES OF ENZYME PATTERN IN THE SYMPATHETIC NERVOUS SYSTEM OF ADULT MICE AFTER SUBMAXILLARY GLAND REMOVAL; RESPONSE TO EXOGENOUS NERVE GROWTH FACTOR
Authors: Hendry I. A. , Thoenen H. 
Published: October 2006

Abstract—Removal of the submaxillary glands, the apparent site of NGF synthesis in adult mice, caused a decrease in the activity of all the enzymes involved in the biosynthesis of noradrenaline in the peripheral sympathetic nervous system. Thus, tyrosine hydroxylase (phenylalanine 4‐monooxygenase, EC 1.14.16.1) DOPA decarboxylase (EC 4.1.1.28.) and dopamine β‐hydroxylase (EC 1.14.17.1.) showed reduced activity 10 days after removal of the submaxillary glands in both superior cervical and stellate ganglia. This decrease in enzyme activity persisted up to 100 days after surgery. The fourth enzyme studied, choline acetyl‐transferase (EC 2.3.1.6.) which is exclusively localized within the presynaptic cholinergic terminals of the ganglia was not affected by sialectomy. A dose of 50 μg NGF/animal/day given over 4 days was only able to restore the enzyme activity to control levels in the superior cervical ganglia of sialectomized mice whereas in stellate ganglia the enzyme activities rose above control levels to a similar extent in sialectomized and non‐sialectomized animals.These results provide biochemical evidence that NGF may play a role not only during the growth and normal development of the peripheral sympathetic nervous system but also in the maintenance of its functional integrity in the adult animal.
THE PRIMARY BIOCHEMICAL LESION LEADING TO THE DELAYED NEUROTOXIC EFFECTS OF SOME ORGANOPHOSPHORUS ESTERS
Authors: Johnson M. K. 
Published: October 2006

Abstract—In contrast with neurotoxic organophosphates of the type (RO)2P.O.X several phosphinates (R2P.O.X) cause prolonged inhibition of ‘neurotoxic esterase’in vivo but do not cause delayed neurotoxicity even after repeated administration. Prior administration of these phosphinates protected hens against the neurotoxic effects of several organophosphates: this protection lasted until about 70 per cent of the enzyme site again became available for phosphorylation. In this respect phosphinates behave like carbamate and sulphonyl fluoride inhibitors of ‘neurotoxic esterase'. It is proposed that the development of delayed neurotoxicity requires phosphorylation of the esterase followed by hydrolysis of one remaining phosphoryl ester bond to produce a charged monosubstituted phosphoric acid group attached to the protein. Generation of such a group could not occur after inhibition by the protective phosphinates, carbamates or sulphonates. It is proposed that the charged group is responsible for the metabolic disturbance leading to degeneration of long axons.
IN VIVO METHYLATION AND TURNOVER OF RAT BRAIN HISTONES
Authors: Duerre J. A. , Lee Catherine Ting 
Published: October 2006

Abstract— The turnover of the different histone components from brain nuclei was studied after the administration of l‐[3H]lysine and l‐[14C‐methyl]methionine to newborn rats. The radioactivities of the different histone subfractions as well as other proteins were determined over a 280‐day period. Biphasic type decay curves (3H and 14C) were obtained for total brain histones and all the subfractions. From 6 to 40 days of age the half life of total brain histones was 19 days. After reaching brain maturity the half life was 132 days. The lysine rich histone (F1) was found to turnover the fastest of all the histones, having half lives of 13 and 112 days, respectively. The decay curve for the slightly lysine rich histones (F2a2, F2b) gave half lives of 25 days up to 40 days of age and 189 days after reaching brain maturity. The arginine rich histones (F2a1, F3) gave a half life of 32 days up to 40 days of age, while no turnover was observed after maturity. The turnover rates of the methyl groups and/or methionyl residues did not vary significantly from the turnover rates of the lysyl residues in the F2 and F3 histones. The lysine‐rich histones did not contain significant amounts of methionyl residues or methyl groups.Amino acid analysis of the brain histones revealed that about 3·6 per cent of the lysyl residues in the slightly lysine rich histones were methylated, mainly as ε‐N‐dimethyllysine. About 13 per cent of the lysyl residues in the arginine rich histones were methylated, mainly as ε‐N‐monomethyllysine and ε‐N‐dimethyllysine.
ELECTROPHORETIC PROFILES OF AQUEOUS‐SOLUBLE PROTEINS OF HUMAN CEREBRAL CORTEX: POPULATION AND DEVELOPMENTAL CHARACTERISTICS1
Authors: Caplan R. , Cheung Shelly C.‐Y. , Omenn G. S. 
Published: October 2006

Abstract—Aqueous‐soluble brain proteins from 100 adult humans have been screened by discontinuous polyacrylamide and by continuous‐SDS‐polyacrylamide electrophoresis for evidence of genetically determined variation. In addition 42 adult Macaca nemestrina and 36 inbred strains of mice were screened in the SDS‐continuous system. No variation in position of major bands was found within species, although differences in relative intensity of staining were noted. Fetal human cerebral cortex gave profiles of aqueous‐soluble proteins distinguishable from that of adults. After affinity chromatography on Concanavalin‐A‐agarose, adult samples gave one band on SDS‐polyacrylamide gels, while fetal samples gave the same band plus an additional band, presumably representing glycoproteins.
RELATIVE IMPORTANCE OF CHOLINE TRANSPORT TO SPONTANEOUS AND POTASSIUM DEPOLARIZED RELEASE OF ACh
Authors: Carroll P. T. , Goldberg A. M. 
Published: October 2006

Abstract—The importance of extracellular choline transport to spontaneous and K+ depolarized release of ACh was studied using mouse brain cortex minces. The results suggest that extracellular choline transport is not essential to spontaneously released ACh but is essential to K+ depolarized ACh release. Similar cumulative amounts of choline and ACh were found in the incubation media following incubation of minces in either Krebs or 35 mm‐K+ Krebs suggesting the same production of free choline during both conditions. Double reciprocal plots of choline accumulation by non‐depolarized cortex minces yield high and low affinity components. Conversely, similar analysis of choline accumulation by depolarized minces yields a single Michaelis constant (68 μm) similar to the low affinity (50 μm) Michaelis constant determined for choline accumulation by non‐depolarized minces. Kinetic analysis of ACh release as a function of extracellular choline concentration during K+ depolarization also yields a Michaelis constant of 68 μm These data suggest a link between choline transport and ACh release during K+ depolarization.
TAURINE IN THE BRAIN AND LIVER OF THE DEVELOPING HUMAN AND MONKEY
Authors: Sturman J. A. , Gaull G. E. 
Published: October 2006

Abstract—The concentrations of taurine in brain and liver from human fetuses (2nd trimester) and adults and from Rhesus monkeys from mid‐gestation, through birth and neonatal life to maturity have been measured. The concentration of taurine in human and monkey fetal brain was 4‐5‐fold higher than that in adult monkey brain. In human fetal brain the concentration of taurine decreased linearly with increasing crown‐rump length (r=−0·75; P < 0·001). In fetal monkey brain, no correlation with gestational age was found. After birth, the concentration of taurine in monkey brain decreased linearly with increasing age (r=−0·96; P < 0·001) until values comparable to those found in the adult were reached 8‐9 months after birth, approximately the end of weaning.The concentration of taurine in liver both from fetal humans and from fetal monkeys was approximately twice that in mature liver. Concentrations of taurine similar to those found in adult liver were reached within a few days of birth, compared to several months for brain.These results suggest that taurine may be associated with brain development in addition to any functional role it may play in the mature brain.
DETERMINATION OF BRAIN‐SPECIFIC ANTIGENS IN SHORT TERM CULTIVATED RAT ASTROGLIAL CELLS AND IN RAT SYNAPTOSOMES
Authors: Bock Elisabeth , Jørgensen O. S. , Dittmann L. , Eng L. F. 
Published: October 2006

Abstract—The brain‐specific antigens 14·3·2, GFA, A5, F3, D1, D2, D3 and C1 were quantitated in a short‐term astroglial cell culture taken as a model of glial cells, and in synaptosomes, synaptosomal membranes and synaptic vesicles as neuronal material. Furthermore, the antigens were quantitated in newborn rat brain, as this served as the starting material for the cell culture. The membrane antigens C1, D1, D2 and D3 were absent from the cultured astroglia, indicating a neuronal origin for these antigens. C1 was enriched 3‐fold in synaptosomes and synaptosomal membranes and more than 10‐fold in synaptic vesicles indicating that this antigen might be a marker protein for nerve endings. The name Synaptin is introduced for this antigen. Conversely, the data on the antigens D1, D2 and D3 indicated that these antigens were not restricted to the synaptosomes although they were of neuronal origin. Trace amounts of the cathodal part of the heterogeneous cytoplasmic antigen 14·3·2 were present in the cell culture, possibly originating from a few contaminating neurons. The cytoplasmic antigens A5 and F3 were found both in the astroglial culture and in the synaptosomal fraction. F3, however, was found in low concentration in the synaptosomes and 3‐fold enriched in newborn rat brain compared to rat brain from 35‐day‐old rats or to 21‐day‐old brain cell cultures. It was therefore regarded as a brain specific fetal antigen. The antigen GFA was highly enriched in the astroglial culture compared to whole brain and only trace amounts were found in the synaptosomal fraction supporting the astroglial origin of this antigen.
REGIONAL DIFFERENCES IN HIGH AFFINITY CHOLINE TRANSPORT VELOCITY IN GUINEA‐PIG BRAIN
Authors: Carroll P. T. , Buterbaugh G. G. 
Published: October 2006

Abstract—The kinetic parameters of choline accumulation by synaptosomes prepared from different regions of guinea‐pig brain (cortex, brainstem, and cerebellum) were determined. Choline was accumulated by a high affinity transport process for all regions tested and the apparent Michaelis constants were similar. However, the apparent maximal velocities of choline accumulation for the brain regions differed; the differences were related to the amount of acetylcholine formed by the respective regions. The results suggested that the maximal velocity of the high affinity transport process may reflect the density of cholinergic nerve endings within brain regions.
A COMPARATIVE STUDY OF THE METABOLISM OF DE NOVO SYNTHESIZED FATTY ACIDS FROM ACETATE AND GLUCOSE, AND EXOGENOUS FATTY ACIDS, IN SLICES OF RABBIT CEREBRAL CORTEX DURING DEVELOPMENT
Authors: Carey E. M. 
Published: October 2006

Abstract—Slices of rabbit cerebral cortex, from the foetal stage to the adult have been used to compare lipid synthesis from fatty acids synthesized de novo from [U‐14C]glucose and [1‐14C]acetate, with lipid synthesis from exogenous albumin‐bound [1‐14C]palmitate. Incorporation into cellular lipid has been determined in terms of DNA, protein, wet wt. of tissue and wet weight of whole brain. On a wet wt. basis, maximum incorporation of glucose carbon into lipid occurred in the foetal brain while lipid synthesis from acetate and palmitate was maximum at 4–14 days after birth. Glucose and acetate were incorporated into a diversity of lipids (with increasing amounts of phosphatidylcholine synthesized during maturation), while palmitate was incorporated into the free fatty acid and triglyceride fractions. A greater proportion of acetate was incorporated into fatty acids of chain‐length longer than C16 compared with the incorporation of palmitate. However, on a molar basis de novo synthesized and exogenous palmitate were elongated, desaturated and incorporated into phospholipids at a similar rate, while exogenous palmitate was incorporated to a greater extent than de nova synthesized fatty acid into the triglyceride fraction. This difference in metabolism may be due to the different size of the non‐esterified fatty acid pool in the two situations. At the period of their most active formation, the very long‐chain fatty acids may be synthesized from a pool of the C18 series of fatty acids (saturated and monoenoic) not in equilibrium with the bulk of C18 acids in cerebral lipids. This could be a pool of acyl groups derived from ethanolamine phospholipids.