bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTS OF DI‐ISOPROPYLFLUOROPHOSPHATE ON THE METABOLISM OF CHOLINE AND PHOSPHATIDYLCHOLINE IN RAT BRAIN
Authors: Dross K. 
Published: October 2006

Abstract—The subcutaneous administration of 2·0 mg DFP per kg to rats causes a diminution in the lysophosphatidylcholine content in the brain, which is followed by a decrease of glycerylphosphorylcholine concentration and by a reduced post mortem choline increase. This supports the hypothesis that a post mortem increase in choline is due to phosphatidylcholine breakdown. Since the amount of phosphatidylcholine in brains of di‐isopropylfluorophosphate‐treated rats increases, it is concluded that phospholipase A is inhibited by di‐isopropylfluorophosphate, which corresponds to findings of other authors in vitro. The activity of glycerylphosphorylcholine diesterase (EC 3.1.4.2) is not altered.
AMINO ACID TRANSPORT IN PERIPHERAL NERVE: ENERGY AND SODIUM DEPENDENCE
Authors: Wheeler D. D. 
Published: October 2006

Abstract— The energy and sodium dependence of the several carrier‐mediated mechanisms for amino acid uptake have been studied in frog sciatic nerve. The different transport mechanisms are found to be variable in their dependence on sodium and metabolic energy. Saturable uptakes of lysine, phenylalanine and valine are relatively independent of the presence or absence of sodium in the incubation medium, indicating that uptakes by those mechanisms subserving basic, large neutral amino acids, and those amino acids containing aromatic or heterocyclic ring structures are largely sodium independent. Saturable uptakes of glutamic acid, proline, glycine and β‐alanine are considerably reduced in the absence of sodium; thus carrier mechanisms for uptake of acidic, small neutral amino acids, β‐alanine and proline are highly sodium dependent. The efficacies of several cations in substituting for sodium is variable; greatest inhibitions are found when potassium is used to replace sodium.With the exception of proline, those mechanisms found to be sodium dependent are also found to be energy dependent, since they are inhibited by both DNP and lowered temperature. Although proline uptake is sodium dependent, proline uptake is stimulated by DNP and relatively insensitive to lowered temperature.
ATPase ACTIVITY OF NEUROBLASTOMA CELLS IN CULTURE
Authors: Ledig M. , Ciesielski‐Treska J. , Cam Y. , Montagnon D. , Mandel P. 
Published: October 2006

Abstract—Neuroblastoma cells were cultured in the presence of fetal serum. When serum was omitted from the growth medium and also when dibutyryl cyclic AMP or insulin were added without omitting serum, there was a growth of neuron‐like processes which was in most cases accompanied by an increase in Na+‐K+ ‐ATPase activity, whereas Mg2+‐ATPase activity increased to a lesser extent. The increase in ATPase activities was related to cell density. When the ATPase activities were measured in the presence of 0·25 m‐sucrose or 1% deoxycholate the specific activities were decreased. There was no loss of activity during storage at –20°C for several days when 20% glycerol was added to the medium.
AXONAL TRANSPORT OF LABELLED PROTEINS IN SENSORY FIBRES OF RABBIT VAGUS NERVE IN VITRO
Authors: McLean W. G. , Frizell M. , Sjöstrand J. 
Published: October 2006

Abstract—Rabbit vagus nerves and nodose ganglia were incubated in vitro for up to 24 h in two‐compartment chambers. After the introduction of [3H]leucine or [3H]fucose to the ganglion compartments a rapid anterograde axonal transport of labelled proteins or glycoproteins occurred at rates of 330 ± 44 mm/day and 336 ± 30 mm/day respectively. Accumulation of [3H]leucine‐labelled proteins proximal to a ligature on the nerve was unaffected by a delay of up to 6 h between removal of the nerve and labelling in vitro. Accumulation was prevented by inhibition of protein synthesis in the ganglion but not in the axon and was inhibited in a graded manner by colchicine.
POLYAMINE METABOLISM IN THE BRAIN AND LIVER OF THE DEVELOPING MONKEY
Authors: Sturman J. A. , Gaull G. E. 
Published: October 2006

Abstract— The concentrations of putrescine and the polyamines, spermidine and spermine, along with the specific activities of the enzymes involved in their biosynthesis, ornithine decarboxylase, S‐adenosylmethionine decarboxylase and spermidine synthase have been measured in brain and liver of the developing Rhesus monkey from mid‐gestation, through birth and neonatal life to maturity. The results suggest that it is an increased concentration of putrescine and an increased specific activity of ornithine decarboxylase which are associated with the rapid growth of fetal brain during the middle of gestation. By the end of two‐thirds of gestation, both of these parameters have attained values similar to those found in mature brain. The concentration of spermidine in brain and the specific activities of S‐adenosylmethionine decarboxylase and spermidine synthase are lower in fetal brain than adult brain and increase slowly after birth to reach values similar to those of the adult only after several months. These results provide additional evidence that in the mature brain spermidine serves some function other than one associated with rapid growth.Fetal liver at mid‐gestation was characterized by increased concentrations of both putrescine and spermidine and increased specific activities of the enzymes which synthesize them. By two‐thirds of gestation, values similar to those found in adult liver had been attained. Liver has thus reached maturity with regard to polyamine metabolism by this time.
TRANSPORT OF CHOLESTEROL IN THE CHICK OPTIC SYSTEM
Authors: Rostas J. A. P. , McGregor Angela , Jeffrey P. L. , Austin L. 
Published: October 2006

Abstract—After injection of radioactive cholesterol into the vitreous humour of chicks, cholesterol is axonally transported along the optic nerve to the contralateral optic tectum. In the optic nerve of young chicks cholesterol is only transported at the slow rate whereas in the sciatic nerve of adult chicks it is transported at both the fast and slow rates. This difference is not due to age or a peculiarity of avian species as the same difference exists in mice. Estimates of the cholesterol content of tissues and the amount of cholesterol transported suggests the existence of small rapidly turning over pools of cholesterol in nerves. Due to its great metabolic stability, cholesterol is a useful and specific marker for slow transport in the optic nerve and thus may prove suitable for the mapping of neuronal projections.
TERMINAL DEOXYNUCLEOTIDYL TRANSFERASE IN HUMAN BRAIN
Authors: Viola M. V. , Cole Margery L. , Norton P. 
Published: October 2006

Abstract—A DNA polymerase lacking template direction for base selection has been partially purified from human brain. The molecular size, optimum reaction conditions, initiator preferences and chemical inhibitors of the brain enzyme were similar to calf thymus terminal deoxynucleotidyl transferase (TdT). TdT has been found only in the thymus, and now in brain. The possibility exists that its function is related to biological property unique to these two organs.
5′‐ADENINE MONONUCLEOTIDES TN SYNAPTOSOMAL PREPARATIONS FROM GUINEA PIG NEOCORTEX: THEIR CHANGE ON INCUBATION, SUPERFUSION AND STIMULATION
Authors: Barberis C. , McIlwain H. 
Published: October 2006

Abstract—–(l) The contents of potassium and of ATP, ADP and AMP of homogenates of guinea pig neocortex in 0.32 M‐SUCROSE, and of synaptosomal preparations derived therefrom, were determined and effects of incubation, superfusion and stimulation of the preparation were examined. The synaptosome preparations in M‐SUCTOSe carried a smaller content of 5′‐nucleotide per unit protein than did the homogenate from which they were derived. However, the proportion of synaptosomal nucleotides present as ATP was markedly greater than in the homogenate as a whole, the adenylate energy‐charge being 83% greater in the synaptosomes than in the homogenate. Dilution of the synaptosomal preparation from the 1 M‐sucrose to isotonic sucrose, decreased the contcnt of ATP per unit protein, but did not change the sum ATP + ADP + AMP.(2) Examined as deposited beds during 5 to 20 min incubation in oxygenated glucose‐bicarbonate salines, synaptosomal K content and adenylate energy charge increased. These changes were sustained during a subsequent 40 min of incubation and also during superfusion. During such continued superfusion, electrical stimulation caused diminution of the ATP and the adenylate energy charge of the beds, as also did superfusion with fluids of increased K‐content.(3) Lactate formation by the superfused beds was relatively stable during 30 min incubation. By electrical stimulation, the rate of lactate formation was increased by up to 30%. Increase in the potassium content of superfusion fluids could however increase lactate production 2.4‐fold. The basis for these actions is discussed.
CYTOCHROMES IN BRAIN MITOCHONDRIA FROM LAMBS WITH ENZOOTIC ATAXIA
Authors: Smith R. M. , Osborne‐white W. S. , Odell B. L. 
Published: October 2006

AbstractMitochondria from the cerebral cortex of untreated lambs from areas in which enzootic ataxia occurred showed a lower content of haem a (from cytochromes a and a 3) than mitochondria from control lambs with adequate copper but the haems of cytochromcs b2 c1 and c were not depleted. Cytochrome oxidase activity was closely correlated with the content of haem a (P<0.001) but there was no correlation with total mitochondrial copper which was always present in molar exccss of haem a. It is concluded that the lowered cytochrome oxidase activity in mitochondria from untreated lambs is immediately attributable to depletion of haem a. In clinically ataxic lambs that showed degradation of myelin in thc spinal cord, brain cytochrome oxidase was depressed by no more t han 60%. Arguments are advanced that this depletion was not sufficiently severe to have led to respiratory constraint
UPTAKE AND METABOLISM OF 5‐METHYL‐TETRAHYDROFOLIC ACID BY RAT BRAIN SLICES
Authors: Schnell Mercedes , Ordóñez Luis A. 
Published: October 2006

Abstract— The uptake and metabolism of CH3‐[14C]tetrahydrofolic acid (MTHF) by rat brain was studied in vitro. At physiological concentrations, (10−10m), a small net uptake of the labeled compound was observed in whole brain, as well as in the cerebrum, cerebellum and brain stem slices. The passive diffusion observed in the presence of KCN proceeded slowly, equilibrium being achieved after 120 min. DEAE–Sephadex chromatography of the radioactive labeled material present in the tissue showed that a pseudo‐uptake mechanism was operative. Eighteen percent of the label was found in methionine, and after pre‐incubation with KCN this was reduced to approx 9%. Neither dietary folate deficiency, nor the availability of a methyl group acceptor (l‐DOPA), were able to increase the observed pseudo‐uptake. Nevertheless, l‐DOPA reduced the proportion of label found as unmetabolized MTHF in the slices at the end of the incubation (47% vs 59%) while increasing other (methylated ?) metabolites. The pseudo‐uptake process was not detected in newborn animals; it increased linearly with age, reaching adult levels at 10 days of age.It is suggested that uptake mechanisms are not responsible for maintaining brain folate levels during folate deficiencies in the adult animal.
BINDING CHARACTERISTICS OF 125I‐LABELLED TETANUS TOXIN TO PRIMARY TISSUE CULTURES FROM MOUSE EMBRYONIC CNS
Authors: Dimpfel W. , Habermann E. 
Published: October 2006

Abstract— The interaction of 125I‐labelled tetanus toxin with cells in tissue cultures derived from embryonic CNS has been studied.The optimum toxin binding occurs about 2–3 weeks after transfer of the cells to culture conditions. The amount of label bound per culture was doubled at this time in comparison to the fourth day nfter inoculation.The amount of toxin bound depends on the concentration applied. It reaches its maximum 8 h after application then decreases slowly. Low amounts of radioactivity were still detectable 97 h after washing off the unbound toxin. Up to 80% of the label can be replaced by simultaneous application of‘cold’toxin. Fixation of the toxin is higher at 4°C than at 37°C.Preincubation of the cultures with neuraminidase prevents about 75% of the binding. The presence of cytochalasin B leads to a small but reproducible decrease of binding, whereas colchicine had no measurable effect.The radioactive (1251) material was identified by a double‐isotope technique in disc gel electrophoresis before and after reductive cleavage of its disulphide bonds. In every test is was indistinguishable from 131I‐labelled toxin added as standard.Our results largely parallel those obtained with synaptosomes and other systems. They suggest that gangliosides might be the acceptor molecules, and that the culture system will be suitable for studying the actions of this toxin in vitro.
TAURINE IN DEVELOPING RAT BRAIN: SUBCELLULAR DISTRIBUTION AND ASSOCIATION WITH SYNAPTIC VESICLES OF [35S]TAURINE IN MATERNAL, FETAL AND NEONATAL RAT BRAIN
Authors: Rassin D. K. , Sturman J. A. , Gaull G. E. 
Published: October 2006

Abstract—The concentration of taurine in the brain of the fetus in several species is higher than that found in the mature animal. In order to explore the functional significance of this, we have studied the subcellular distribution of taurine and [35S]taurine in the brain of the mother, the fetus and the neonate after [35S]taurine was administered to pregnant rats.In maternal brain, the distribution of taurine and of radioactivity (all of which was recovered from brain as taurine) in the subcellular fractions of maternal brain were essentially identical and were recovered primarily in two fractions (72% taurine, 71% [35S]taurine was soluble, S3; 16% and 17%, respectively, was in the crude mitochondrial and synaptosomal fraction, P2). After further fractionation of P2, most of the taurine and [35S]taurine were in the cytoplasmic, O, and the synaptosomal, B, fractions.In the neonatal brain, shortly after birth there was a decrease in taurine and [35S]taurine recovered in the supernatant fraction, S3, accompanied by an increase in the percentage of taurine and [35S]taurine recovered in the crude mitochondrial fraction. A small percentage of taurine and [35S]taurine was consistently recovered in the synaptic vesicle fraction. Fractionation of the synaptic vesicles on a gel column separated the vesicle bound taurine completely from the free taurine: approx 1% of the taurine in the synaptic vesicle fraction was eluted with vesicles and could not be released by hypo‐osmotic shock.The pattern of development in subcellular fractions of neonatal rat brain labelled with [35S]taurine via intraperitoneal injections of the pregnant mother may be an indication of maturation or protection of putative taurinergic nerve endings.
PRELIMINARY ESTIMATES OF THE DOPAMINE β‐HYDROXYLASE CONTENT AND ACTIVITY IN PURIFIED NORADRENERGIC VESICLES1
Authors: Klein R. L. , Kirksey D. F. , Rush R. A. , Goldstein M. 
Published: October 2006

Abstract—The dopamine β‐hydroxylase (DβH) content and activity of large dense‐core noradrenergic vesicles purified from bovine splenic nerve were determined using two assay procedures : enzymic activity expressed in Units per mg protein and homospecific activity based on radioimmunoassay expressed in Units per mg DβH antigen. Approximately two‐thirds of the total enzyme activity is latent in these vesicles, even after various treatments designed to compromise vesicle integrity. DβH can be completely unmasked by brief treatment with 0.01‐0.05% Triton X‐100 and activity increases from 0.20 to 0.64 Units per mg vesicle protein. Calculations based on both assay methods suggested that an average of 7% (range 3‐15%) of the total vesicle protein was DβH and that the average vesicle contained about 4 molecules of enzyme (range 2‐9 molecules). The estimated homospecific activities indicated an average of 25 and 50% (range 18‐72%) of the vesicle enzyme was inactive in the various samples using the two antibodies. The vesicle can synthesize up to 30 molecules of noradrenaline/s per molecule of DβH at near optimal substrate concentration, and 60‐270 molecules of norepinephrine/s per vesicle. The assumptions used in the various calculations were critically analyzed and, based on the methods employed, it is tentatively considered to be unlikely that there could be more than 5‐12 molecules of DβH per vesicle. The possibility that circulating DβH originates primarily, if not exclusively, from the large dense‐core vesicle type is considered and the functional implications of the data support the concept of vesicle reuse during several cycles of exocytosis involving a quantal size equal to a fraction of the vesicle transmitter content.
HIGH AFFINITY UPTAKE OF L‐GLUTAMATE AND L‐ASPARTATE BY GLIAL CELLS
Authors: Balcar V. J. , Borg J. , Mandel P. 
Published: October 2006

Abstract—The presence of an efficient, high affinity uptake system specific for L‐glutamate and L‐aspartate has been demonstrated in cultured glial cells originating from syrian hamster astroblasts (line NN). The system was found to be temperature dependent, to require sodium ions and its structural specificity is similar to systems studied previously in brain slices and synaptosomes. Co‐culturing of the glial cells with neuroblastoma cells brought about only minor changes in structural specificity while values of kinetic parameters remained virtually unchanged. The temperature dependence and the susceptibility to metabolic inhibitors suggest that the uptake is mediated by an active transport system.
DETECTION OF A SOLUBLE SEROTONIN‐BINDING PROTEIN IN THE MAMMALIAN MYENTERIC PLEXUS AND OTHER PERIPHERAL SITES OF SEROTONIN STORAGE
Authors: JONAKAIT G. M. , TAMIR H. , RAPPORT M. M. , GERSHON M. D. 
Published: October 2006

Abstract—Groups of neurons intrinsic to the mammalian myenteric plexus have been shown to have both tryptophan hydroxylase and a specific uptake mechanism for serotonin. They are probably serotonergic. A soluble protein with a high binding affinity for serotonin, similar to a protein previously found in rat brain by TAMIR & HUANG (1974), has now been found in the myenteric plexus of both rabbit and guinea pig. Partial purification of the protein from the rabbit's myenteric plexus by ammonium sulfate fractionation increased the ratio of specific to nonspecific serotonin binding almost 3‐fold. Two dissociation constants for serotonin binding were obtained by equilibrium dialysis: 6.7 × 10−10 M and 4.8 × 10−7 M. The protein was similar to the soluble serotonin‐binding protein of CNS: the indole derivatives 5, 6‐ and 5, 7‐dihydroxytryptamine, and 6‐hydroxytryptamine inhibited serotonin binding by 50% at 10−7 M; norepinephrine was a poor inhibitor of serotonin binding; most of the serotonin‐protein complex had a very high molecular weight and did not penetrate a 6.5% acrylamide gel. The appearance of the serotonin binding protein during development of the intestine in fetal rabbit correlates closely with the development of a serotonin uptake mechanism by nerves of this tissue and precedes the ingrowth of the adrenergic innervation. In‐vitro administration of 6‐hydroxydopamine to adult animals has no effect on the binding capacity for serotonin. Binding activity in denervated preparations is only 1/5 that of innervated tissue. It is concluded that the serotonin‐binding protein, which has been found associated with serotonergic pathways in the CNS, is found associated with serotonergic neurons in the periphery as well. Since a similar serotonin‐binding protein is also found in sheep thyroid, which stores but does not take up serotonin, the protein may be a component of the serotonin storage mechanism.
D‐ AND L‐STEREOISOMERS OF ALLYLGLYCINE: CONVULSIVE ACTION AND INHIBITION OF BRAIN L‐GLUTAMATE DECARBOXYLASE
Authors: ORLOWSKI MARIAN , REINGOLD DIANE F. , STANLEY M. E. 
Published: October 2006

Abstract—DL‐Allylglycine was resolved into the L‐ and D‐stereoisomers using hog kidney acylase. Both isomers were active as convulsants after administration to mice. The dose of D‐allylglycine required to induce convulsions was greater than that of the L‐isomer. Studies on the concentration of the two isomers in brain suggest that the lower effectiveness of D‐allylglycine is partially due to its slower penetration into the brain through the blood‐brain barrier.Both isomers of allylglycine inhibited brain glutamate decarboxylase in vitro to approximately the same extent, however, in vivo L‐allylglycine inhibited the enzyme more strongly than the D isomer. Concentrations of allylglycine which caused a significant inhibition of L‐glutamate decarboxylase in vivo were ineffective in inhibiting the enzyme in vitro. Oxidation products derived from L‐ or D‐allylglycine by the action of either L‐ or D‐amino acid oxidase caused an almost complete inhibition of the enzyme in vitro. It is suggested that a common intermediate derived from the two isomers (possibly 2‐keto‐4‐pentenoic acid) is responsible for the in vivo inhibition of L‐glutamate decarboxylase and possibly also for the induction of convulsions.
OLIGODENDROGLIA FROM HUMAN AUTOPSIED BRAIN: BULK ISOLATION AND SOME CHEMICAL PROPERTIES1
Authors: Iqbal Khalid , Grundke‐Iqbal Inge , Wisniewski Henryk M. 
Published: October 2006

Abstract— Oligodendroglia were isolated from fresh and frozen human autopsied brains by a modification of our technique for isolation of neuronal perikarya and astroglia (Iqbal & Tellez‐Nagel, 1972). Cerebral white matter was minced in a hypertonic hexose‐Ficoll buffered medium, passed through successive screens of decreasing pore size, and the cells were then separated on a discontinuous sucrose density gradient using low speed centrifugation. Cells could also be isolated by substituting sucrose for hexoses in the cell isolation medium. About 95% of the isolated cells had morphology characteristic of oligodendroglia. The usual contaminants in this fraction were capillary fragments, red blood cells, and a few astrocytes. Free myelin was only sparsely seen. About 5–10% of the isolated oligodendroglia had one or more loops of loose membranes extending from the cell plasma membrane. These membraneous loops resembled myelin. The ultrastructural preservation of the cells was poor. The average yield per gram of wet tissue was 52 million cells amounting to 2.4 mg protein, 283 μg DNA, and 94 μg RNA. The protein, DNA, and RNA contents per average cell were 47, 5.3, and 1.8 pg respectively. About 50% of the tissue DNA was recovered as isolated cells, suggesting a larger proportion of oligodendroglia to astroglia, the other principal cell type in human white matter.Comparison of the total protein profiles of the isolated oligodendroglia with those of the purified human myelin on sodium dodecyl sulfate‐polyacrylamide gels revealed the presence of all human myelin constituent proteins in the isolated cells except the intermediate (or DM‐20) myelin proteins. Densitometry of the gels stained with Fast Green showed that the ratio of protein bands corresponding to myelin encephalitogenic basic protein (BP) to myelin proteolipid protein (PLP) in the isolated cells was three‐fold as high as in purified human myelin. The oligodendroglial BP which constituted about 14% of the total cell protein contents, also coelectrophoresed with the myelin BP on pH 4.3 polyacrylamide gels. Furthermore, the two dimensional peptide maps of the tryptic digest of the cell BP labelled with 125I were also identical to the similarly treated myelin BP. The data suggest that the BP can be used as a chemical marker for oligodendroglia.