bluuebunny/crossref_metadata_2025 huggingface dataset:
DEVELOPMENTAL PATTERNS OF GANGLIOSIDES AND OF PHOSPHOLIPIDS IN CHICK RETINA AND BRAIN
Authors: Dreyfus H. , Urban P. F. , Edel‐Harth S. , Mandel P.
Published: October 2006

Abstract— The changes in phospholipids and gangliosides during ontogenesis of chick retina have been compared with those in brain. Three phases of accumulation of ganglioside NeuNAc in the retina were detected. In contrast, brain NeuNAc rapidly increased during embryonic life until hatching, followed by a slower increase up to the adult stage. The phospholipid changes in retina and in brain occur in a‐similar manner to the variations observed for gangliosides, however in retina the changes of phospholipid content are less marked than in brain, during embryonic life. There were marked changes in the retina and brain ganglioside patterns with age. Gd3 and Gd1b decreased rapidly in per cent; correspondingly, Gd1a increased during embryonic life and became the major ganglioside in place of Gd3. There was a similarity between ganglioside patterns of chick retina and brain. Except for some slight variations during embryonic life, the retinal phospholipid pattern did not change noticeably.
EFFECTS OF CHRONIC CONSUMPTION OF ETHANOL AND SUCROSE ON RAT WHOLE BRAIN 5‐HYDROXYTRYPTAMINE
Authors: Moscatelli E. A. , Fujimoto Karen , Gilfoil T. C.
Published: October 2006

Abstract— Whole brain 5‐hydroxytryptamine (5‐HT) levels were determined after 3 weeks in rats chronically consuming ethanol, in pair‐fed controls, and in pair‐fed controls consuming sucrose in quantities isocaloric to the ethanol of the first group. A cryogenic harvesting and storage technique was developed to insure accurate measurement of whole rat brain 5‐HT. It was found that whole brain 5‐HT is completely stable for at least 16 days after decapitation into liquid N2 followed by storage of frozen whole heads at – 70°C. Using this technique and spectrophotofluorometric 5‐HT assays, no differences were found in whole brain 5‐HT among the three groups. Chronic consumption of ethanol and sucrose apparently lead to no chronic change in rat whole brain 5‐HT.
POLYACRYLAMIDE GEL ELECTROPHORESIS OF RAT BRAIN ACETYLCHOLINESTERASE: ISOENZYME CHANGES FOLLOWING PARATHION POISONING1
Authors: Vijayan V. K. , Brownson R. H.
Published: October 2006

Abstract—

Brain acetylcholinesterase (EC 3. 1. 1. 7) isoenzymes of 15‐ and 30‐day‐old rats were found to be inhibited by 2.5 mg/kg and 1.25 mg/kg dosage levels of intraperitoneally administered parathion (E‐605; O, O‐diethyl‐p‐nitrophenyl phosphorothionate). With 2.5 mg/kg dose level, the response of isoenzymes in 15‐ and 30‐day‐old rats was similar. At both ages, there was no significant sex difference in the degree of depression of the isoenzymes.

There were no significant regional differences in the degree of inhibition of acetylcholinesterase isoenzymes in the rat brain. At 1.25 mg/kg dosage level, a differential isoenzyme inhibition was evident, with the major isoenzyme (isoenzyme 3) exhibiting the greatest sensitivity to the inhibitor in all brain areas examined.

The course of isoenzyme depression and recovery following the administration of parathion differed in brain, serum and skeletal muscle. Whereas brain isoenzymes exhibited most marked inhibition at 2 h after injection, inhibition of serum and skeletal muscle isoenzymes was more prolonged. At 4 h after injection, these isoenzymes were still inhibited while brain isoenzymes had recovered to a substantial degree. Twenty four h following the injection of parathion, when brain and serum acetylcholinesterase isoenzymes had returned to control activity levels, isoenzymes of skeletal muscle demonstrated only minimal recovery.
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.
THE ELEVATION OF CEREBRAL HISTAMINE‐N‐AND CATECHOL‐O‐METHYL TRANSFERASE ACTIVITIES BY l‐METHIONINE‐dl‐ SULFOXIMINE1
Authors: Schatz R. A. , Sellinger O. Z.
Published: October 2006

Abstract— The administration of the convulsant, l‐methionine‐dl‐sulfoximine (MSO), increased histamine N‐methyl transferase (E.C. 2.1.1.8) (HMT) activity in rat and mouse brain and, to a lesser extent, catechol‐O‐methyl transferase (E.C. 2.1.1.6) (COMT) activity in rat brain. The duration of this effect was shortened by co‐administration of l‐methionine. The increased HMT activity was seen in 5 or 7 rat brain regions tested. l‐Methionine administration had no effect on the activity of either enzyme. Partially purified HMT preparations from rat or guinea‐pig brain exhibited no alterations in activity after the in vitro addition of MSO or l‐methionine over a wide range of histamine and S‐adenosyl‐l‐methionine concentrations. Rat brain COMT was equally unaffected by MSO and l‐methionine. The in vitro inhibition of HMT and COMT by S‐adenosyl‐l‐homocysteine was the same whether tested on preparations derived from MSO‐treated or control animals. The data are discussed with respect to the possible involvement of aberrant methylation processes in the MSO‐induced seizure.
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
PURIFICATION OF RAT BRAIN CHOLINE ACETYLTRANSFERASE1
Authors: ROSSIER J.
Published: October 2006

Abstract— The purification of choline acetyltransferase (ChAc) has been hampered by the increasing instability of the enzyme in the course of purification. By working with a high concentration of protein and by adding glycerol to the enzyme, the stability was increased. The purification was performed by centrifuging twice, at low and high salt concentrations, precipitation by ammonium sulphate and chromatography on carboxymethyl–Sephadex, hydroxylapatite and Sephadex G 100. The final steps were performed by using chromatography on an immunoabsorbent; this consists of agarose‐coupled gammaglobulins of antisera devoid of any activity against ChAc itself and directed against other proteins still present in the purest ChAc preparation achieved by conventional biochemical techniques. The purest rat brain ChAc preparation had a specific activity of 20 μmol/min/mg of protein after a 30,000‐fold purification. The enzyme was not homogeneous in polyacrylamide gel electrophoresis performed either at pH 4.5 or with sodium dodecyl sulphate. Pure ChAc from rat brain would have a specific activity of approximately 100 μmol/min/mg of protein.
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.
ALTERATIONS OF CYCLIC NUCLEOTIDE‐RELATED ENZYMES AND ATPase DURING UNILATERAL ISCHEMIA AND RECIRCULATION IN GERBIL CEREBRAL CORTEX
Authors: Schwartz Joan P. , Mrsulja B. B. , Mrsulja B. J. , Passonneau Janet V. , Klatzo I.
Published: October 2006

Abstract— Several enzyme activities were determined in gerbil cerebral cortex during unilateral ischemia or in the post‐ischemic period following 1 h of ischemia. Adenylate cyclase and Na + ‐K + ‐activated ATPase showed essentially the same pattern. Neither enzyme changed during ischemia but the activities decreased on recirculation to 40–60% of right side control by 5 h. The ATPase had returned to control level by 20h; the adenylate cyclase by 7 days of recirculation. Particulate cyclic AMP‐dependent protein kinase in the ischemic left hemisphere decreased throughout the 6h of ischemia. It remained depressed in the first 5 h of the post‐ischemic period but returned to control by 20 h. The soluble protein kinase activity, the soluble cyclic AMP and cyclic GMP phosphodiesterase and the Mg2+ dependent ATPase did not change significantly during the ischemic or post‐ischemic periods. The results suggest that ischemia and/or recirculation may affect cellular membranes and membrane‐bound enzymes, in particular. Furthermore, the results imply that despite apparent metabolite recovery during the post‐ischemic period, enzymatic changes are occurring that may be important for both the quality of recovery and the response to further ischemic insult.
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

–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

—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

—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

—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

Evidence 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.
SUBCELLULAR FRACTIONATION STUDIES RELATED TO THE PROCESSING OF NEUROSECRETORY PROTEINS IN APLYSIA NEURONS
Authors: Loh Y. Peng , Sarne Y. , Daniels M. P. , Gainer H.
Published: October 2006

Abstract— Neurosecretory cells (bag cells and R3–14 neurons) in the abdominal ganglion of Aplysia californica were ‘pulse‐chased’ in [3H]leucine and comparisons of the labeled protein profiles from the total cell homogenate versus a crude ‘neurosecretory granule’ fraction on acid‐urea polyacrylamide gels were made, The data provides indirect support for the hypothesis that some of the post‐translational processing of the neurosecretory proteins occurs intragranularly (Lohet al, 1975). In the case of the Bag cells the initial processing of the 29,000 daltons precursor appears to occur extragranularly, possibly in the rough endoplasmic reticulum cisternae.
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.
DNA POLYMERASES IN FRACTIONATED RAT BRAIN NUCLEI
Authors: Norton P. , Viola M. V.
Published: October 2006

Abstract— —Adult rat brain nuclei were separated by discontinuous sucrose gradient centrifugation into astrocyte enriched, neuron enriched, and oligodendrocyte/microglia fractions. Nuclear fractions were subjected to velocity sucrose gradient centrifugation and gradient fractions assayed using relatively specific reaction mixtures for DNA polymerase‐α, ‐β and TdT. NEM resistant DNA polymerase activity (DNA polymerase‐β) was detected in equivalent amounts in all nuclear fractions. High molecular weight NEM sensitive activity (DNA polymerase‐α) was found primarily in the neuron enriched fraction. The significance of the presence of DNA polymerase‐α, an enzyme thought to be involved in DNA replication, in a cell incapable of cell division is unknown. TdT was detected in all fractions with increased activity in the neuron enriched fraction. The finding of TdT in thymocytes and neurons further supports the hypothesis that this enzyme is involved in the storage of noninherited information.
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.
AN ADAPTATION OF THE PUSH‐PULL CANNULA METHOD TO STUDY THE IN VIVO RELEASE OF [3H]DOPAMINE SYNTHESIZED FROM [3H]TYROSINE IN THE CAT CAUDATE NUCLEUS: EFFECTS OF VARIOUS PHYSICAL AND PHARMACOLOGICAL TREATMENTS
Authors: Nieoullon A. , Cheramy A. , Glowinski J.
Published: October 2006

Abstract— The release of [3H]dopamine ([3H]DA) continuously synthesized from l‐[3,5–3H]tyrosine from the caudate nucleus of the cat was estimated in halothane anaesthetized or‘encéphale isolé’animals. For this purpose, an improved superfusion cannula, avoiding tissue damage, was used. The best localization for the tip of the superfusion cannula was found first by determining the topographical distribution of endogenous DA within the caudate nucleus. A rostro‐caudal heterogenous distribution of the transmitter was detected.

In perfusion experiments, l‐[3,5–3H]tyrosine was introduced continuously at a rate of 33μl/min. [3H]DA was the only catecholamine found in serial 15 min fractions as revealed by cochromatography. The spontaneous release of [3H]DA was greater in anaesthetized than in ‘encéphale isolé’ cats; it represented 150 and 100 times the blank value, respectively.

Depolarization by K+ (30 mm) applied locally in the striatum or by electrical or mechanical stimulation of the substantia nigra caused a transitory increase in [3H]DA release. Conversely, a decrease in nerve activity induced by tetrodotoxin (5 × 10−‐7 m) or by electrocoagulation of the substantia nigra was associated with a decline in the amounts of [3H]DA in superfusates. A temporary reduction in [3H]DA release could also be obtained by a short‐lasting cooling block of the substantia nigra.

As expected, d‐amphetamine (10−‐5 m) and benzotropine(10−‐7 m) added to the superfusing medium increased [3H]DA release.

These pharmacological results, as well as the changes in [3H]DA release observed after various manipulations of the activity of dopaminergic neurones, confirms the validity and the high sensitivity of this approach.
DOPAMINE BIOSYNTHESIS FROM L‐TYROSINE AND L‐PHENYLALANINE IN RAT BRAIN SYNAPTOSOMES: PREFERENTIAL USE OF NEWLY ACCUMULATED PRECURSORS1,2
Authors: Kapatos G. , Zigmond M.
Published: October 2006

Abstract— The biosynthesis of dopamine (DA) from L‐tyrosine (Tyr) and L‐phenylalanine (Phe) was investigated using synaptosomes prepared from the striatum and olfactory tubercle of the rat. The formation of 14CO2 from either carboxyl labeled precursor occurred exclusively within the synaptosome following hydroxylation and subsequent decarboxylation. The optimum pH for the formation of DA was 6.2 and was independent of precursor and tissue source. As pH increased beyond this optimum, synthesis from Tyr declined more rapidly than that from Phe. Synthesis obeyed Michaelis–Menton kinetics when expressed as a function of the specific activity of precursor in the medium. It was characterized by an overall Km (approx 0.9 μM) which was independent of precursor and tissue source, and was considerably lower than the Kt for accumulation of precursor by synaptosomes (15.3 and 13.3 μM for Tyr and Phe, respectively). While each precursor was an uncompetitive inhibitor of DA synthesis from the opposing labeled amino acid, Tyr was a more effective inhibitor of synthesis from Phe (Ki= 1.5 μM) than was Phe an inhibitor of synthesis from Tyr (Ki= 9.2 μM). Tryptophan inhibited synthesis competitively (Ki= 15.2 and 13.2 μM for synthesis from Tyr and Phe, respectively), and DA inhibited non‐competitively (Ki= 1.1 and 0.42 μM for Tyr and Phe, respectively). A model of DA synthesis within the synaptosome is presented which attempts to integrate these data. A major feature of this schema is the proposal that newly accumulated precursor does not mix rapidly with endogenous precursor pools but rather is preferentially converted to DA.
GAMMA‐AMINOBUTYRIC ACID BINDING IN MAMMALIAN BRAIN: RECEPTOR‐LIKE SPECIFICITY OF SODIUM‐INDEPENDENT SITES
Authors: Greenlee Donald V. , Van Ness Paul C. , Olsen Richard W.
Published: October 2006

The binding of radioactive gamma‐aminobutyric acid to particulate fractions of mammalian brain was measured by a centrifugation assay, using repeatedly washed and frozen and thawed membranes and sodium‐free assay conditions. Studies of over 30 structural analogues indicated an excellent correlation between inhibition of gamma‐aminobutyric acid binding and activity as agonists or antagonists on gamma‐aminobutyric acid synapses as reported in the neurophysiology literature. In particular, binding was inhibited by low concentrations of the gamma‐aminobutyric acid receptor‐specific drugs muscimol, homotaurine, and isoguvacine, but very poorly by analogues such as 2,4‐diaminobutyric acid and nipecotic acid which specifically inhibit gamma‐aminobutyric acid transport but are inactive on synaptic receptors. Binding was inhibited by the synaptic antagonist bicuculline but not by picro‐toxinin. Thus, these binding sites show the chemical specificity required of physiological receptors for the neurotransmitter gamma‐aminobutyric acid.
CITRATE AS THE PRECURSOR OF THE ACETYL MOIETY OF ACETYLCHOLINE
Authors: Sterling Gerald H. , O'Neill John J.
Published: October 2006

Abstract— Rat brain cortex slices were incubated with glucose labeled with either 3H or 14C in the 6‐position. The 3H/14C ratios and the incorporation of radioactivity into lactate, citrate, malate and acetylcholine were determined. While the 3H/14C ratio of lactate was close to that of glucose, the ratios in the acetyl moiety of acetylcholine and the acetyl (C‐4,5) portion of citrate decreased in a similar proportion. This was interpreted as indirect evidence for the participation of citrate as a precursor to the acetyl moiety of acetylcholine. Two inhibitors of the citrate cleavage pathway: n‐butylmalonate, an inhibitor of citrate transport and (‐)‐hydroxycitrate, an inhibitor of ATP‐citrate lyase were studied for their effect on acetylcholine synthesis. N‐butylmalonate (10 mM) and (‐)‐hydroxycitrate (7.5 mM) led to a decrease in the per cent of 14C recovered as acetylcholine. In each instance the 3H/14C ratio in acetylcholine was higher in the presence of inhibitor while the corresponding ratios in lactate and citrate (C‐4.5) remained unchanged. From the results, it is suggested that citrate is involved in the transport mechanism of acetyl units from its site of synthesis in mitochondria to the site of acetylcholine synthesis in the cytosol.
CELL SURFACE PROTEINS OF CULTURED BRAIN CELLS AND THEIR RECOGNITION BY ANTI‐CEREBELLUM (ANTI‐NS‐4) ANTISERUM
Authors: Goridis Christo , Joher Muhammed A. , Hirsch Marierose , Schachner Melitta
Published: October 2006

Abstract— Surface proteins of cultured young postnatal mouse cerebella and embryonic mouse cerebral hemispheres were identified by Iactoperoxidase‐catalysed radioiodination and by their interaction with an anti‐mouse cerebellum antiserum (anti‐NS‐4 serum) which recognizes surface components on brain cells. Several (8 10) iodinated polypeptides are recognized by radioautography after polyacrylamide gel electrophoresis. Their surface location was confirmed by their sensitivity to mild trypsin treatment on intact cells. Iodinated polypeptides from cells of non‐nervous tissues showed a different gel pattern. Immuno‐precipitates of solubilizcd surface‐iodinated cerebellar cells with anti‐NS‐4 serum contained two prominent labeled proteins with apparent molecular weights of 200 × 103 and 145 × 103. These proteins were also biosynthetically labeled with [3H]leucine. The 145 × 103 molecular weight component was also found in immunoprecipitates prepared from embryonic cerebral cells, but the 200 × 103 molecular weight component was replaced by a broad peak with an apparent molecular weight of around 250 × 103.
MUSCIMOL UPTAKE, RELEASE AND BINDING IN RAT BRAIN SLICES
Authors: Johnston G. A. R. , Kennedy S. M. E. , Lodge D.
Published: October 2006

Abstract— The GABA analogue, muscimol, was taken up relatively inefficiently compared to GABA by slices of rat cerebral cortex at 37 C. Muscimol uptake followed saturation kinetics (Km ImM. Vm 0.1 μmol g mini and showed an absolute dependence on sodium ions. The relative susceptibilities of muscimol uptake and GABA high affinity uptake to a variety of inhibitors, including (‐)‐nipecotic acid. (+)‐2.4‐diaminobutyric acid and arecaidine, and the stimulation of muscimol efflux by 50μM‐GABA, suggest that muscimol and GABA share some common transport carriers. Since L‐histidine inhibited muscimol uptake hut not GABA high affinity uptake, at least part of the observed muscimol uptake may be mediated by the 'small basic’amino acid transport system. Muscimol appeared to he taken up into nerve terminals, since uptake was inhibited by the neuronal uptake inhibitor cis‐3‐aminocyclohexanecarboxylic acid but not by the glial uptake inhibitor β‐alanine. Muscimol efflux was stimulated in a calcium‐dependent manner by an increased potassium ion concentration.

Sodium‐independent binding of muscimol was observed in slices of rat cerebral cortex at 4 C. Binding could be inhibited by a variety of substances. including GABA, isoguvacine and (+)‐bicuculline methochloride, which are known to inhibit the binding of muscimol to putative GABA receptors associated with synaptic membranes purified from rat brain.
BIOCHEMICAL STUDIES OF NERVE EXCITABILITY: THE USE OF PROTEIN MODIFYING REAGENTS FOR CHARACTERIZING SITES INVOLVED IN NERVE EXCITATION
Authors: Baumgold Jesse , Matsumoto Gen , Tasaki Ichiji
Published: October 2006

Abstract—

A variety of protein modifying reagents were applied to crab nerves extracellularly while monitoring the action potentials. These reagents were also applied to squid giant axons intracellularly, while monitoring the action potentials, and for some compounds the membrane resistance and resting membrane potential. The effects of modifying sulfhydryl, imidazole, amino, and methionine groups on the nerve excitability were examined. These studies revealed that imidazole and sulfhydryl groups are present on the axoplasmic side of the axolemma and that chemical modification of these groups leads to block of nerve conduction. When various reagents which modify amino groups were applied either from the inside of squid axons or to the outside of crab nerves, the excitability was not usually affected. The suppression of excitability due to the effect of some of these amino reagents could be attributed to the modification of groups other than amino groups. The hydrolytic action of cyanogen bromide was found to be effective in bringing about conduction block, suggesting that there exist accessible methionine groups in protein molecules which must remain intact in order to maintain nerve conduction.
SUBCELLULAR DISTRIBUTION OF DOPAMINE IN SUBSTANTIA NIGRA OF THE RAT BRAIN: EFFECTS OF γ‐BUTYROLACTONE AND DESTRUCTION OF NORADRENERGIC AFFERENTS SUGGEST FORMATION OF PARTICLES FROM DENDRITES1
Authors: Hefti F. , Lichtensteiger W.
Published: October 2006

Abstract— The subcellular distribution of dopamine (DA) in substantia nigra from individual male rats was studied with a fractionation procedure on microscale. After differential centrifugation the distribution of DA coincided with that of noradrenaline (NA) which can serve as a marker for synaptosomes in this area. The proportion of DA/NA concentrations was about 1–2 in most fractions. Sixty per cent of nigral DA was found in P2 (17,000 g). When P, was layered on a continuous density gradient, DA and NA peaked at the density of 1.0–1.2 M‐sucrose. Since DA‐containing particles covered a relatively broad range on this gradient, particles between 0.7 and 1.3 M‐sucrose were collected with a discontinuous density gradient. Sixty per cent of DA from P2, was found in this subfraction.

The particles containing DA could have been derived from dendrites or axon collaterals of nigrostriatal neurones or represent precursor DA in noradrenergic (NA) terminals. The role of collaterals was investigated by comparing the effect of γ‐butyrolactone (GBL, 750 mg/kg, 1 h) on DA concentrations in subcellular fractions from substantia nigra and caudate‐putamen. In caudate‐putamen, GBL produced a marked increase of DA in total homogenates and subcellular fractions except P3, whereas DA concentrations remained unchanged in all fractions from substantia nigra. This speaks against a contribution from DA terminals.

The proportion of DA contained as precursor in NA terminals was analysed after destruction of the NA input to substantia nigra by two methods. A single injection of 6‐hydroxydopamine into the IV ventricle decreased nigral NA by 5574, DA only by 17%. Unilateral electrolytic lesions in the pontine tegmentum affected NA concentrations in homogenates and fraction P2 of the ipsilateral substantia nigra to a much greater extent than DA. From the results obtained with the two approaches, it is estimated that precursor DA in particulate fractions does not exceed 10%.

Our observations indicate that dendrites of the DA neurones in substantia nigra can form particles which behave like synaptosomes on density gradients centrifugation; they may be termed ‘dendrosomes’. According to the proportion of DA found in the particulate fractions at least 4040% of nigral DA appear to be localised in dendrites.
MODULATION OF γ‐GLUTAMYL TRANSPEPTIDASE ACTIVITY FROM BOVINE CHOROID PLEXUS
Authors: Prusiner Paul E. , Prusiner Stanley B.
Published: October 2006

Abstract— The catalytic activity of γ‐glutamyl transpeptidase (γ‐GTP) from bovine choroid plexus has been shown to be subject to modulation by a variety of effectors. L‐Alanine and L‐serine not only functioned as acceptor substrates to which γ‐glutamyl moieties could be transferred, but also as noncom‐petitive inhibitors of the reaction in the presence of the dipeptide acceptor substrate glycylglycine. In contrast, D‐alanine does not function as an acceptor substrate, but does noncompetitively inhibit the transfer of γ‐glutamyl groups to glycylglycine. Similarly, borate ions inhibited y‐GTP noncompetitively, while a mixture of L‐serine and borate were potent uncompetitive inhibitors of the reaction with a Ki of 0.6 mM. Several dicarboxylic acids, including maleate, maleylglycine, and malonate, inhibited γ‐GTP; this inhibition was acceptor substrate‐dependent. The inhibition of γ‐GTP by maleate was competitive with respect to the acceptor substrate glycylglycine.
VESICULAR STORAGE AND RELEASE OF ACETYLCHOLINE IN TORPEDO ELECTROPLAQUE SYNAPSES
Authors: Suszkiw J. B. , Zimmermann H. , Whittaker V. P.
Published: October 2006

Abstract— The disposition of newly synthesized ACh subsequent to depletion of vesicular endogenous ACh by stimulation was studied in the electromotor nerve terminals of Torpedo marmorata using [3H]acetate as a precursor of ACh. Little vesicular [3H]ACh could be isolated from tissue immediately after stimulation at 1 Hz. After 3 h post‐stimulation recovery the newly synthesized [3H]ACh is found predominantly in a subpopulation of vesicles distinct from the vesicles containing most of the endogenous poorly labelled ACh. Restimulation of the tissue causes release of highly labelled ACh with a specific radioactivity (SRA) comparable to that of the newly synthesized [3H]ACh in the highly labelled subpopulation of vesicles and significantly greater than the SRA of ACh in the main vesicular pool or the total tissue.