bluuebunny/crossref_metadata_2025_split huggingface dataset:
COMPARATIVE STUDIES OF GUINEA PIG AND BOVINE MYELIN BASIC PROTEINS. PARTIAL CHARACTERIZATION OF CHEMICALLY DERIVED FRAGMENTS AND THEIR ENCEPHALITOGENIC ACTIVITIES IN LEWIS RATS
Authors: Martenson R. E. , Deibler Gladys E. , Kramer A. J. , Levine S. 
Published: October 2006

Abstract—Guinea pig and bovine myelin basic proteins were chemically cleaved at the carboxyl peptide bonds of methionyl and tryptophanyl residues to yield several fragments. Comparison of the bovine fragment consisting of the first 20 residues of the protein with the corresponding guinea pig fragment showed that the latter differs in containing histidine and glycine (one residue of each), an additional threonyl residue, and one fewer alanyl residues. Comparison of the bovine fragment consisting of the C‐terminal 54 residues of the protein (residues 117‐170) with the corresponding guinea pig fragment showed that the latter differs in containing one fewer histidyl and leucyl residues and an additional phenylalanyl residue. Tests of encephalitogenic activity in Lewis rats showed that these two fragments from both species were much less active, on a molar basis, than the uncleaved protein. On the other hand, examination of the bovine fragments consisting of residues 1‐116 and 21‐116 and the corresponding fragments obtained from the guinea pig protein revealed activity at least as high as that of the respective uncleaved proteins.
PURIFICATION AND KINETIC PROPERTIES OF ATP: CITRATE OXALOACETATE LYASE FROM RAT BRAIN1
Authors: Szutowicz A. , Stȩpień M. , ŁYsiak W. , Angielski S. 
Published: October 2006

Abstract— A method for a partial purification of ATP:citrate oxaloacetate lyase from rat brain is described.The Lineweaver–Burk plots of velocity vs citrate concentration are biphasic in the presence of fixed concentrations of MgCl2. Therefore two values of Km, corresponding to low and high concentrations of citrate, can be determined. When MgCl2 is added in equimolar concentrations with citrate, a monophasic plot with one Km of 0.13 mm is obtained. The Km value for MgATP2‐ was independent of citrate concentration, being equal to 0.40–0.43 mm. The Km for CoA was 0.0007 mm.ADP and Pi are competitive inhibitors with respect to ATP. Ki for MgADP− is equal to 0.13 mm. dl‐isocitrate and cis‐aconitate are partially competitive inhibitors with respect to citrate with Ki values of 5.8 and 4.8 mm, respectively. α‐Ketoglutarate and pyruvate are noncompetitive inhibitors with respect to ATP and citrate, with Ki values equal to 9 and 45 mm, respectively.The physiological significance of these effectors for the regulation of citrate lyase activity in brain is discussed.
A METHOD FOR MEASURING BRAIN PROTEIN SYNTHESIS RATES IN YOUNG AND ADULT RATS
Authors: Dunlop D. S. , van Elden W. , Lajtha A. 
Published: October 2006

Abstract—The injection of large quantities of radioactive amino acid precursor is proposed as a technique for determining rates of cerebral protein synthesis in vivo. In this way the specific radioactivity of the amino acid precursor in the brain is maintained at a relatively constant level for at least 2 h. Injections of 10–15 μ mol of valine per g body weight result in nearly constant rates of incorporation of radioactivity and do not appear to inhibit cerebral protein synthesis in adult or young (2–6 day old) rat brain. Similar rates were obtained in young rat brain with lysine and histidine. Rates of protein synthesis in cerebral hemisphere were for 2‐day‐olds 2·1 per cent replacement of protein bound amino acid per h and for adult 0·62 per cent per h. Advantages and disadvantages of the procedure are discussed.
REGIONAL LEVELS OF GLUCOSE, AMINO ACIDS, HIGH ENERGY PHOSPHATES, AND CYCLIC NUCLEOTIDES IN THE CENTRAL NERVOUS SYSTEM DURING HYPOGLYCEMIC STUPOR AND BEHAVIORAL RECOVERY1
Authors: Gorell J. M. , Dolkart Pamela H. , Ferrendelli J. A. 
Published: October 2006

Abstract—The effects of insulin‐induced hypoglycemic stupor and subsequent treatment with glucose on mouse cerebral cortical, cerebellar and brain stem levels of glucose, glycogen, ATP, phosphocreatine, glutamate, aspartate and GABA and on cerebral cortical and cerebellar levels of cyclic AMP and cyclic GMP have been measured. Hypoglycemia decreased glucose, glycogen and glutamate levels and had no effect on ATP levels in all three regions of brain. GABA levels were decreased only in cerebellum. Aspartate levels rose in cerebral cortex and brain stem, and creatine phosphate increased in cerebral cortex and cerebellum. In the hypoglycemic stuporous animals, cyclic GMP levels were elevated in cerebral cortex and depressed in cerebellum whereas cyclic AMP levels were unchanged from control values. Intravenous administration of 2.5–3.5 mmol/kg of glucose to the hypoglycemic stuporous animals produced recovery of near normal neurological function within 45 s. Only brain glucose and aspartate levels returned to normal prior to behavioral recovery. These results suggest that of the several substances examined in this study, only glucose and perhaps aspartate have important roles in the biochemical mechanisms producing neurological abnormalities in hypoglycemic animals.
INHIBITION BY NEOMYCIN OF POLYPHOSPHOINOSITIDE TURNOVER IN SUBCELLULAR FRACTIONS OF GUINEA‐PIG CEREBRAL CORTEX IN VITRO
Authors: Schacht J. 
Published: October 2006

Abstract—The addition of 10−5 M to 10−3 M neomycin to incubations of subcellular fractions of guinea‐pig cerebral cortex increased the labelling of phosphatidylinositol phosphate and decreased the labelling of phosphatidylinositol diphosphate by [γ‐32P]ATP. The effect was observed in all subcellular fractions tested and depended on the cationic form of the antibiotic. Similar effects on lipid labelling were exerted by related aminoglycosidic antibiotics, by neamine, spermine and poly‐L‐lysine. Other neomycin fragments, antibiotics, local anesthetics or small polyamines were ineffective. Neomycin also inhibited the enzymatic hydrolysis of 32P‐polyphosphoinositides. The addition of the drug to aqueous dispersions of these lipids increased the turbidity and lowered the pH of the suspensions. It is suggested that the effects of neomycin on polyphosphoinositide metabolism result from the formation of an ionic complex between the lipids and the antibiotic.
LOCALIZATION OF THE ANTIGENS D1, D2 AND D3 IN THE RAT BRAIN SYNAPTIC MEMBRANE
Authors: Jørgensen O. S. 
Published: October 2006

Abstract—The inside‐outside localization of the nervous system specific membrane proteins D1, D2 and D3 was investigated by a immunoabsorption technique.It was found that D1 was located at least partly on the outside of the synaptic membrane in contrast to D3 which was inside on the membrane, facing the cytoplasm. The protein D2 was outside on the synaptic membrane, and it was found very accessible to the antiserum.It is speculated that D2 might be involved in the axonal‐dendritic recognition process during synaptogenesis
IMPAIRED SYNTHESIS OF ACETYLCHOLINE IN BRAIN ACCOMPANYING MILD HYPOXIA AND HYPOGLYCEMIA
Authors: Gibson G. E. , Blass J. P. 
Published: October 2006

Abstract— Lowering the concentration of oxygen or of glucose to which mouse and rat brains were exposed impaired the synthesis of acetylcholine from labelled precursors in vivo.Histotoxic hypoxia induced with KCN or anemic hypoxia induced with NaNO2 (to oxidize hemoglobin to methemoglobin) reduced incorporation of [2H4]choline into acetylcholine. This change in acetylcholine metabolism occurred with doses of KCN or NaNO2 which did not alter the concentrations of ATP or ADP or the adenylate energy charge. Hypoglycemia induced by large doses of insulin also reduced the incorporation of [2H4]choline into acetylcholine. Both hypoxia and hypoglycemia increased the concentration of choline in the brain. The specific activity of choline did not decrease in hypoxia; it did not decrease enough in hypoglycemia to explain the reduced incorporation of [2H4]choline into acetylcholine.Pretreatment with the cholinesterase inhibitor physostigmine delayed the onset of both seizures and death in mice after induction of hypoxia by large doses of NaNO2. Pretreatment with physostigmine also decreased the number of mice dying within 3 h after the induction of hypoglycemia with large doses of insulin. These observations suggest that the effects of hypoxia and hypoglycemia interfere with the synthesis of a critical pool of acetylcholine.The incorporation of labelled precursors into acetylcholine related linearly to both the cytoplasmic redox state (NAD/NADH ratio) and to the NAD/NADH potential across the mitochondrial membrane. The redox potential of NAD/NADH in the cytoplasm was calculated from the [pyruvate]/[lactate] equilibrium and the redox potential of NAD/NADH in the mitochondria from the [NH4][2‐oxoglutar‐ate]/[glutamate] equilibrium. The potential across the mitochondrial membrane was calculated from the difference.These observations indicate that carbohydrate oxidation is one of the factors on which the synthesis of the neurotransmitter acetylcholine depends closely in mouse and rat brain.
METABOLISM OF GLUTAMATE AND RELATED AMINO ACIDS IN THE 10‐DAY‐OLD MOUSE BRAIN: EXPERIMENTS WITH LABELLED ACETATE AND β‐HYDROXYBUTYRATE
Authors: Van den Berg C. J. , Ronda G. 
Published: October 2006

Abstract– The pattern of incorporation of [3H, 1‐14C]‐ and [3H. 2‐14C]acetate into glutamate and related amino acids was studied in the brain of 10‐day‐old mice. A comparison of these patterns with those obtained for the adult brain led to the suggestion that the glutamate pool labelled directly by acetate is a much larger fraction of the total glutamate pool in the 10‐day‐old brain than it is in the adult brain.Some data on the pattern of labelling of brain amino acids by 3‐hydroxybutyrate. glucose and acetate support the hypothesis that direct carboxylation of pyruvate is somewhat more active in the immature than in the mature brain.Differences in the labelling patterns of free and protein‐bound brain amino acids by acetate, do indicate that the free amino acid pool labelled by acetate is not the precursor pool for protein synthesis.
METABOLIC RESPONSE TO FOCAL PENICILLIN SEIZURES IN RAT: SPIKE DISCHARGE VS. AFTERDISCHARGE1
Authors: Collins R. C. 
Published: October 2006

Abstract– The correlations among clinical events, electrocorticogram, histology, size of focus, and biochemical changes were examined in a model of focal penicillin seizures in rats. Ten units of penicillin injected into the motor cortex were found to be the threshold dose for producing repetitive spike discharges. These were associated with synchronous contralateral muscle jerks which reached a peak intensity in 10 min and fell off rapidly in 45–90 min. The half‐life of penicillin in the cortex was 15 min, with little diffusion from the site of injection. The size of the metabolic focus was determined by autoradiography with [2‐14C]deoxyglucose and was 6.5 times larger than the diffusion of penicillin. Increased glucose utilization appeared in the focus and in cortical columns in the contralateral homo‐typic cortex.Thirty times more penicillin (>300 units) was required to produce spikes with afterdischarge than to product spikes alone. Afterdischarges correlated with contralateral tonic‐clonic seizures and occurred only after 1 h of exposure to penicillin. These lasted 10‐45 s each and recurred over 3 to 4h. The size of the metabolic focus determined by [2‐14C]deoxyglucose during afterdischarges was 4.6 times larger than the focus exhibiting spike discharges alone.Tissue substrates were measured in the seizure focus, homotypic ‘mirror’ cortex, and cortex remote from the focus in paralyzed ventilated animals. During repetitive spike discharge there was a fall in high energy compounds in the focus (phosphocreatine, 4.91 → 4.24 mmol/kg; ATP, 2.62 → 2.17 mmol/kg) and a rise in lactate (1.41 → 2.79 mmol/kg). Changes were similar but less intense in ‘mirror’ and remote cortex. During spikes with afterdischarge, changes in high energy compounds in the focus were of a similar magnitude (phosphocreatine, 4.91 → 3.86 mmol/kg; ATP, 2.62 → 2.46 mmol/kg) but there was a greater rise in lactate (1.41 → 6.32 mmol/kg) and a fall in glucose (2.38 → 1.81 mmol/kg). In contrast, changes in ‘mirror’ and remote cortex during afterdischarges showed an increase in high‐energy compounds.
AMIDOHYDROLASES OF BRAIN;1 ENZYMATIC HYDROLYSIS OF N‐ACETYL‐l‐ASPARTATE AND OTHER N‐ACYL‐l‐AMINO ACIDS
Authors: Goldstein F. B. 
Published: October 2006

Abstract–Mammalian brain contains 2 N‐acylamino acid amidohydrolases resembling the respective kidney enzymes. The anatomical and subcellular distribution of the enzymes; the substrate specificities and interspecies activities of the partially purified amidohydrolases have been studied. A considerable proportion of the amidohydrolase activity of subcellular fractions was found to be associated with the paniculate matter. The increased activities of the particulate enzymes in the presence of Triton X‐100 and chloroacetyl amino acid substrates suggest that significant amounts of the enzymes are in the bound or latent form.
LABELLED PROTEINS IN RABBIT VAGUS NERVE BETWEEN THE FAST AND SLOW PHASES OF AXONAL TRANSPORT
Authors: McLean W. G. , Frizell M. , Sjoustrand J. 
Published: October 2006

Abstract—The profile of axonally transported [3H]leucine‐labelled proteins in motor fibres of rabbit cervical vagus nerve was studied at time intervals after the appearance of fast‐phase and before the slow‐phase proteins, viz. 16 h after labelling of the cell bodies. No moving peak of radioactivity was seen. The transport blocking agents colchicine and vinblastine in vitro showed no difference in the mechanisms of anterograde transport between fast‐phase and later‐phase proteins, but differed in their effects on the retrograde flow. Double‐ligature experiments in vitro indicated the presence of rapidly‐migrating labelled proteins in cervical vagus up to 23.5 h after labelling and demonstrated the retrograde redistribution of proteins from nerve terminals and from a ligature. There was no evidence for an intermediate rate of protein transport.
REGIONAL DISTRIBUTION AND PROPERTIES OF THE GLYCINE CLEAVAGE SYSTEM WITHIN THE CENTRAL NERVOUS SYSTEM OF THE RAT: EVIDENCE FOR AN ENDOGENOUS INHIBITOR DURING IN VITRO ASSAY
Authors: Daly Edward C. , Nadi N. S. , Aprison M. H. 
Published: October 2006

Abstract—The activity of the glycine cleavage system (GCS) was determined in homogenates from five specific regions of the rat CNS (telencephalon, midbrain, cerebellum, medulla‐pons, and spinal cord). An inverse trend was noted between the glycine content and the specific activity of the GCS in the regions. A 25‐fold range in the enzyme activities was found between the telencephalon (highest) and the spinal cord (lowest). The properties of the GCS activity in CNS homogenates agreed with those properties previously described for this system in partially purified preparations of liver and brain mitochondria (Kikuchi, 1973; Bruinet al., 1973). Within the CNS homogenates, the liberation of CO2 from the carboxyl carbon of glycine was quantitatively coupled to the formation of serine.The presence of an endogenous inhibitor(s) within neural tissues was suggested by the non‐additivity of the activities when homogenates from the various regions were combined. Moreover, homogenates of CNS tissue inhibited the GCS activity of liver homogenates, and an inverse relationship was found between the level of GCS activity in a given region of the CNS and its ability to inhibit the GCS activity of liver homogenates. This inhibition of liver activity was greatest when liver was incubated with homogenates of spinal cord (86%) and lowest when incubated with homogenates of telencephalon (20%). Because of this endogenous inhibition, the apparent activity of the GCS measured in vitro may not reflect the contribution of this enzyme system in the metabolism of glycine in vivo. Although the significance of this inhibition is not known, a possible role is discussed for the regulation of the levels in glycine and one‐carbon pools within the CNS.
OXIDATIVE METABOLISM OF THE CEREBRAL CORTEX OF THE RAT IN SEVERE INSULIN‐INDUCED HYPOGLYCAEMIA
Authors: Norberg K. , Siesjou B. K. 
Published: October 2006

Abstract—Measurements were made of organic phosphates, carbohydrate substrates, amino acids and ammonia in the cerebral cortex, as well as of cerebral blood flow and of cerebral metabolic rate for oxygen and glucose in rats that developed an isoelectric EEG pattern (‘coma’) during insulin‐induced hypoglycaemia. The results were compared to those obtained in control animals, as well as in hypoglycaemic animals with an EEG pattern of slow waves and polyspikes. In animals with slow waves and polyspikes, there was a decrease in all citric acid cycle intermediates except succinate and oxaloacetate, and a decrease in the pool size of intermediates. In animals that had an isoelectric EEG for 5–15 min, there were further decreases in citrate, isocitrate, α‐ketoglutarate, malate and fumarate, but since the concentration of succinate (and oxaloacetate) increased, the pool size remained the same. In isoelectric animals, the results revealed extensive utilization of amino acids by both transamination and deamination reactions. However, since glycogen had disappeared and the amino acid pattern was constant after the first 5 min of isoelectric EEG, further oxidation must have occurred at the expense of non‐carbohydrate, non‐amino acid substrates.There were two‐ to three‐fold increases in cerebral blood flow in animals with slow waves and polyspikes and in animals with isoelectric EEG, and no decrease in the cerebral metabolic rate for oxygen. Since less than half of the oxygen consumption could be accounted for in terms of glucose extraction, the data indicate that severe hypoglycaemia is associated with extensive oxidation of endogenous substrates other than carbohydrates and free acids.
PHOSPHOLIPASE ACTIVITY IN SQUID AND FROG AXONS
Authors: Eyrich T. L. , Bakrett D. , Rock P. A. 
Published: October 2006

AbstractEvidence for the presence of phosphatide acylhydrolase activity (EC 3.1.1) in centrifuged homogenate supernatants and extracts of squid giant axons and centrifuged homogenate supernatants of frog sciatic nerve bundles is reported. The enzyme was assayed by measurement of the rate of deacylation of [U‐14C]phosphatidyl choline. The deacylation activity in the nerve homogenate supernatants exhibits: a pH maximum at 7.2–7.4 (25°C); a calcium ion maximum at 12–13 mM‐CaCl2(aq); a Km value of 3.4 × 10−4 M (25°C); and a temperature maximum at 37°C. The activation energy over the range 8–37°C is 5.7 ± 0.2kcal‐mol−1.
TAURINE IN DEVELOPING RAT BRAIN: MATERNAL‐FETAL TRANSFER OF [35S]TAURINE AND ITS FATE IN THE NEONATE
Authors: Sturman J. A. , Rassin D. K. , Gaull G. E. 
Published: October 2006

Abstract—The transfer of [35] taunne, injected intrapentoneally into pregnant rats (near term), to fetal tissues has been measured. Taurine can enter fetal brain as easily as it can fetal liver. In contrast, it cannot enter mature brain as easily as it can enter mature liver. After birth, [35S] taurine, which had been injected into the dam before birth of the pups, continues to accumulate in the brain of the pups for some days. During the neonatal period, the concentration of taurine is decreasing, but the total pool of taurine in the brain is increasing rapidly. In order to help supply this increasing pool, the taurine present in the brain at birth appears to be conserved and an increasing amount of taurine is synthesized in situ. The net result during the neonatal period of development is that brain taurine specific radioactivity decreases and brain taurine has a very slow rate of turnover.
EFFECTS OF INACTIVATION OF BUTYRYLCHOLINESTERASE ON STEADY STATE AND REGENERATING LEVELS OF GANGLIONIC ACETYLCHOLINESTERASE
Authors: KOELLE G. B. , KOELLE WINIFRED ANGENENT , SMYRL ELOISE GABEL 
Published: October 2006

Abstract—The effects of single and repeated injections of tetramonoisopropyl pyrophosphortetramide (iso‐OMPA), a selective inactivator of butyrylcholinesterase (BuChE), were studied on the ganglionic and muscular levels of BuChE and acetylcholinesterase (AChE) in cats during the steady state and following the irreversible inactivation of both enzymes by isopropylmethylphosphonofluoridate (sarin). Single intravenous injections of iso‐OMPA, 3.0 or 6.0 μmol/kg, produced nearly total inactivation of BuChE with no immediate effect on the AChE of the superior cervical (SCG), stellate (StG), and ciliary (CG) ganglia and inferior oblique (10) muscle; regeneration of BuChE occurred at approximately the same rate in the three ganglia, and at 4–6 days the AChE levels were significantly elevated. When single doses of iso‐OMPA were given 1 h following sarin, 2.0 μmol/kg, intravenously, there was a slight increase in the rate of AChE regeneration during the ensuing 2 days. With the repeated injection of iso‐OMPA, 3.0 μmol/kg every 48 h, there was a consistent but not statistically significant reduction in AChE regeneration at 4, 6, 12, and 18 days following sarin in all 3 ganglia. Similar treatment with iso‐OMPA alone produced significant increases in ganglionic AChE at all these periods excepting the longest. The daily injection of iso‐OMPA for 6 days, which maintained ganglionic BuChE at approx 2% of the control values, produced significant reductions in AChE regeneration, but again significant increases in ganglionic AChE levels in cats that did not receive sarin. The IO muscle did not exhibit these effects. A working hypothesis is proposed, that BuChE is a precursor of ganglionic AChE, and that the level of BuChE participates in the regulation of AChE synthesis by inhibition of a preceding rate‐limiting step.
AN ANTIGENIC POLYPEPTIDE FRAGMENT ISOLATED FROM TETANUS TOXIN: CHEMICAL CHARACTERIZATION, BINDING TO GANGLIOSIDES AND RETROGRADE AXONAL TRANSPORT IN VARIOUS NEURON SYSTEMS
Authors: Bizzini B. , Stoeckel K. , Schwab M. 
Published: October 2006

Abstract— The isolation and purification of an antigenic polypeptide fragment from tetanus toxin is described. The main physico‐chemical, chemical, immunological, and pharmacological characteristics of this fragment, designated as B‐IIb fraction, are reported. It is a polypeptide with a molecular weight close to 46,000. Its amino acid composition is on the whole comparable with that of the toxin. It contains one disulphide link and two free sulphhydryl groups which are not directly available for reaction. Tyrosine and lysine were found to be the two N‐terminal groups. However, that B‐IIb fraction has a subchain structure is still to be demonstrated. There is some evidence that B‐IIb fraction may consist of ‘isofragments’. This toxin fragment shows a cross‐reaction with intact toxin and a specific flocculating activity of about three times that of the latter. In contrast, however, B‐IIb fraction exhibits a specific toxicity approximately one hundred thousand times lower than the intact toxin. Although practically atoxic, this toxin fragment is still able to bind to gangliosides with an affinity which is even greater than that of the toxin. It is also capable of migrating towards the central nervous system by a mechanism of retrograde axonal transport as shown in peripheral adrenergic, sensory and motoneurons.These unique features of B‐IIb fraction are discussed in relation to the use of such fragments both for competing in vivo with the attachment of the toxin in the central nervous system and for specifically carrying therapeutic and pharmacological drugs into the central nervous system by neural route.