bluuebunny/crossref_metadata_2025 huggingface dataset:
INCORPORATION IN VIVO DE LA l‐[3H]LEUCINE DANS LES PROTEINES DU CERVELET DE JEUNES RATS NORMAUX, SOUS‐ALIMENTES, HYPERTHYROIDIENS ET HYPOTHYROIDIENS. THE INCORPORATION IN VIVO OF l‐[3H]LEUCINE INTO CEREBELLAR PROTEINS, IN THE YOUNG NORMAL, UNDERFED, HYPERTHYROID AND HYPOTHYROID RAT
Authors: Dainat J.
Published: October 2006

—L'évolution de l'incorporation in vivo de la l‐[3H]leucine dans les protéines totales du cervelet de jeunes Rats normaux, sous‐alimentés, rendus hypo‐ ou hyperthyroïdiens, met en évidence deux phases dans l'évolution de la radioactivité spécifique des protéines en fonction de l'âge :la première phase se caractérise par une radioactivité spécifique élevée, alors que dans la deuxième phase, la radioactivité spécifique décroît fortement puis se stabilise à une valeur faible. La première phase s'étend sur 2 semaines chez les animaux normaux et sous‐alimentés, sur 1 semaine chez les animaux hyperthyroïdiens, et sur 3 semaines chez les animaux hypothyroïdiens. Il semble qu'à la première phase puisse correspondre la dernière ‘poussée’ de prolifération cellulaire, alors que la seconde phase qui débute à la fin de la période de prolifération cellulaire correspondrait à la prépondérance de la différenciation des cellules, puis au maintien du turnover des protéines. Les variations de la radioactivité spécifique des protéines, pourraient refléter les effets des différents traitements sur la prolifération cellulaire de l'organe.

—The evolution of the incorporation of l‐[3H]leucine into cerebellar proteins in vivo in the normal, the underfed, the hypo‐ and the hyperthyroid young rat shows two phases. The first phase exhibits high specified radioactivity values for protein which decrease markedly in the second phase and stabilize at a low level by the third or fourth postnatal week. The duration of the first phase lasts for 2 weeks in the normal and underfed animals, 1 week in the hyperthyroid animals and 3 weeks in the hypothyroid animals. The first phase thus parallels the last 'surge’ of cellular multiplication and the second phase, which begins when cellular multiplication and migration are about over, reflects preponderantly cellular differentiation. Metabolically the latter phase would thus correspond to the period of slowdown of protein turnover to maintenance levels. The results suggest that the variations in the specific radioactivity values in the different physiological states reflect the effects of hypo‐ and hyper‐thyroidism and of underfeeding on the cellular proliferation and differentiation of the cerebellum.
MEMBRANE PROTEINS OF RAT BRAIN: COMPOSITIONAL CHANGES DURING POSTNATAL DEVELOPMENT
Authors: Waehneldt T. V. , Neuhoff V.
Published: October 2006

Abstract— Membrane fractions from forebrain of rat were isolated at ages ranging from 5 to 93 days. Among these fractions were total membranes, three fractions isolated by density gradient centrifugation, and three subfractions which consisted of purified myelin and of two supernatant fractions. All membrane fractions showed an increase in protein content during the first postnatal month; however, only the myelin fraction and one of its supernatant fractions showed a prolonged accumulation. Myelin protein increased continually from 0.17 mg/g brain at 15 days to 8.3 mg/g brain at 93 days.

All fractions were analysed for protein composition by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Characteristic changes in protein composition were noted during postnatal development, most of which were pronounced up to the age of 20 days. Among others was a decrease in histones as compared to other proteins, with a concomitant shift in preponderance from the slow‐ to the fast‐migrating histone band. In parallel, other proteins of high molecular weight became more prominent. No myelin could be isolated at 5 and 10 days. The deposition of myelin proteins was parallelled by the appearance of the Wolfgram protein which points to a close correlation of the Wolfgram protein to the process of myelination.
IN VIVO INHIBITION OF RAT BRAIN PROTEIN SYNTHESIS BY l‐DOPA
Authors: Roel L. E. , Schwartz S. A. , Weiss B. F. , Munro H. N. , Wurtman R. J.
Published: October 2006

Abstract— A study has been made of the effect of a single intraperitoneal dose of l‐DOPA on the in vivo metabolism of [14C]leucine and [14C]lysine by the brain, and on their uptake into brain protein. Administration of 500 mg DOPA/kg to 40‐g rats raised the concentrations of several free amino acids; the only amino acid which underwent a statistically significant increment was alanine. Intracisternally‐injected [U‐14C]leucine was rapidly metabolized to other labelled compounds; DOPA administration did not influence significantly the rate of its metabolism. No similar metabolic change was observed after administering [U‐14C]lysine intracisternally.

Incorporation of [14C]leucine and [14C]lysine into total brain protein was significantly reduced 45 min after DOPA administration. There was also depression of the uptake of labelled amino acid into a supernatant fraction, obtained by high speed centrifugation of the brain homogenate, and into brain microtubular protein (tubulin). Reduced amino‐acid incorporation into brain proteins observed 45 min after l‐DOPA injection coincided with extensive disaggregation of brain polyribosomes. At 120 min after DOPA treatment, disaggregation was no longer significant and there was a smaller depression in labelled amino aicd incorporation, which disappeared completely 240 min after l‐DOPA injection. It is concluded that disaggregation of brain polysomes following DOPA treatment is an accurate reflection of a change in the intensity of brain protein synthesis in vivo.
BRAIN RIBOSOMES IN INTRACRANIAL HYPERTENSION1
Authors: Wasterlain C. G.
Published: October 2006

Abstract— Increased intracranial pressure was produced by perfusion of cerebrospinal fluid (CSF) at various pressures into the lateral ventricles of adult Sprague‐Dawley rats with bilateral chronic intraventricular cannulas. When CSF perfusion was carried out at pressures of 150, 300 or 600 mm of water, brain polysomal profiles were similar to controls. Rats perfused under a pressure of 1500 mm water for 30 min were comatose, had slow electroencephalograms and showed a fall in brain polysomes from 66 to 24 per cent of the total ribosomes (P < 0.01) while ribosomal monomers and dimers increased. These monomers and dimers were completely and reversibly dissociated into subunits in 500 niM KC1 buffers, unless prefixed in formaldehyde. [3H]leucine incorporation into brain ribosomes in vivo was decreased by severe intracranial hypertension. In cell‐free systems in vitro, pathological ribosomes were less active in protein synthesis than controls (P < 0.01) but were at least as readily stimulated by poly U. After intracranial pressure was returned to normal, there was a progressive reassociation of ribosomes into polysomes, even in the presence of Actinomycin D. These findings suggest that during severe intracranial hypertension cerebral protein synthesis is inhibited, perhaps through reversible inactivation of the translation of messenger RNA.
THE CHARACTERIZATION OF SPHINGOLIPIDS FROM NEURONS AND ASTROGLIA OF IMMATURE RAT BRAIN1
Authors: Abe T. , Norton W. T.
Published: October 2006

Abstract— Isolated neuronal cell bodies and astroglia of young (15–20‐day‐old) rat brains were both found to contain small concentrations of a variety of glycosphingolipids, including glucosylceramide, galactosylceramide, sulphatide, dihexosylceramide and gangliosides. These sphingolipids, plus sphingomyelin, were isolated, quantitated and their fatty acid and long chain base patterns determined. These data were compared to similar data obtained on these lipids isolated from whole brain and myelin of rats of the same age range.

Glucosylceramide was found in an amount equal to galactosylceramide in neurons, and accounted for 35 per cent of the total monohexosylceramide in astroglia. Dihexosylceramide was present in nearly the same amount as sulphatide in both cell types.

The sphingolipids of each cell type had characteristic fatty acid patterns. Generally the whole brain fatty acid patterns resembled those of astroglial lipids rather than neuronal lipids. In no case did the cell sphingolipid fatty acids resemble those of myelin. However, the galactosylceramide and sulphatides of both cells had unsubstituted and α‐hydroxy acids, both of which had appreciable quantities of C24 acids.

The ganglioside fatty acids of each cell type were similar and not unusual, but were quite different from those of glucosylceramide and dihexosylceramide; the latter having appreciable quantities of 16:0 and acids longer than 18:0. The ganglioside patterns of these cells were similar and only slightly different from that of whole brain. Long chain bases of sphingolipids were mainly C18‐sphingosine in both cell types, and those of ganglioside and sphingomyelin contained small amounts of C20‐sphingosine.
AXONAL TRANSPORT AND TURNOVER OF PROLINE‐ AND LEUCINE‐LABELED PROTEIN IN THE GOLDFISH VISUAL SYSTEM
Authors: Neale J. H. , Elam J. S. , Neale E. A. , Agranoff B. W.
Published: October 2006

Abstract— The suitability of radioactively labeled proline as a marker of axonally transported protein in the goldfish visual system is further investigated and compared with another amino acid, leucine, in double‐label experiments. Intraocularly injected proline is incorporated into protein in the eye S times more efficiently than is leucine, while local labeling of brain protein from precursor which has left the eye and entered the blood, (observed in the ipsilateral optic tectum) is five‐ to eight‐fold less from proline than from leucine. The difference is attributed to the superior transport of leucine, an essential amino acid, into the brain from the blood. Once in the brain, the apparent rates of incorporation of the two amino acids are similar. Proline‐ or leucine‐labeled, axonally transported proteins have a longer apparent half‐life in the brain than do proteins labeled from intracranial injection of the precursors. By either route, proline‐labeled proteins have a longer apparent half‐life than leucine‐labeled proteins. It is proposed that proline, released from protein breakdown is reutilized to a greater extent than is leucine.
STIMULATION OF SEROTONIN N‐ACETYLTRANSFERASE IN PINEAL ORGAN CULTURE BY DRUGS
Authors: Holz R. W. , Deguchi T. , Axelrod J.
Published: October 2006

Abstract— Drugs such as cocaine, procaine, pheniprazine (Catron) and veratridine, which have actions on sympathetic nerves and nerve terminals, were examined for their ability to increase serotonin N‐acetyltransferase (EC 2.3.1.5; NAT) in pineal organ culture. The absence of potassium (0 KCl) was also examined. NAT is known to respond to β‐adrenergic stimulation. It was found that these drugs and 0 KCl increased the enzyme activity 100 to 2000‐fold in innervated pineals but had virtually no effect in denervated pineals. The effects on innervated pineals were blocked by the β‐blocker propranolol but not by the α‐blocker, phentolamine. These drugs and 0 KCl inhibited to varying degrees [3H] 1‐norepinephrine uptake in pineals. It is concluded that these agents activated the β‐adrenergic receptor on pineal cells by causing an accumulation of extraneuronal norepinephrine. The accumulation of norepinephrine is due, at least in part, to the blockade of norepinephrine reuptake by nerve terminals.

The ability of veratridine to stimulate NAT and to inhibit norepinephrine uptake was reversed by tetrodotoxin, a blocker of sodium permeability in excitable tissue, thus veratridine acts by increasing sodium permeability in nerve terminals. This adds support to the theory that catecholamine uptake is a process that requires a sodium gradient across the nerve terminal membrane.
EFFECT OF l‐DOPA ON BRAIN CONCENTRATION OF DOPAMINE AND HOMOVANILLIC ACID IN RATS AFTER CHRONIC MANGANESE CHLORIDE ADMINISTRATION
Authors: Bonilla E. , Diez‐Ewald María
Published: October 2006

Abstract— Rats chronically treated with a high oral load of MnCl2 showed decreased concentrations of dopamine and HVA in brain. A return to normal values was observed after l‐DOPA injections. This suggests a disturbance in catecholamine metabolism after chronic manganese administration possibly at the level of l‐tyrosine hydroxylase.
EARLY CHANGES IN ACETYLCHOLINE POOLS IN THE HIPPOCAMPUS OF THE RAT BRAIN AFTER SEPTAL LESIONS
Authors: Potempska Anna , Grądkowska Malgorzata , Oderfeld‐Nowak Barbara
Published: October 2006

—After placement of lesions in the hippocampus by electrocoagulation, an increase in bound acetylcholine above control levels was shown. There was no concomitant rise in free acetylcholine. The rise in bound acetylcholine was not due to changes in levels of either acetylcholinesterase or choline acetyltransferase and it is suggested that the interruption of septal impulses and/or alterations in uptake or availability of substrates is responsible.
LOCALIZATION OF EXTRANEURONAL DOPAMINE‐β‐HYDROXYLASE IN RAT SALIVARY GLAND BY IMMUNOFLUORESCENCE HISTOCHEMISTRY
Authors: Wooten G. F. , Jacobowitz D. M. , Saavedra J. M. , Axelrod J.
Published: October 2006

Abstract— Superior cervical ganglionectomy results in a complete noradrenergic neuronal denervation of the rat sublingual‐submaxillary salivary gland. Dopamine‐β‐hydroxylase activity in the serous submaxillary gland falls approximately 90% after noradrenergic denervation; but in the mucinproducing sublingual gland dopamine‐β‐hydroxylase activity is reduced by only 33%. Dopamine‐β‐hydroxylase immunofluorescence in the submaxillary gland is distributed with noradrenergic neurons and is eliminated by superior cervical ganglionectomy. In the sublingual gland dopamine‐β‐hydroxylase immunofluorescence is localized within mucinous acini and small ducts, and the disposition and intensity of staining materials is not affected by noradrenergic denervation for up to 30 days. DBH protein in the sublingual gland had little physiologic activity in vivo. Low levels of authentic dopamine‐β‐hydroxylase activity were detected in saliva. Thus, dopamine‐β‐hydroxylase protein is present in the sublingual gland in an extraneuronal location and appears to be a secretory product of the gland.
SUBCELLULAR DISTRIBUTION OF 5‐HYDROXYTRYPTAMINE IN RAT BRAIN DURING DEVELOPMENT: EFFECT OF DRUGS AND FASTING
Authors: Tissari A. H. , Raunu E. M.
Published: October 2006

Abstract— Distribution of brain 5‐HT content between the high‐speed supernatant and particulate fractions under normal and experimental conditions was studied in postnatal and adult rats. In adult and 35‐day‐old rats the 5‐HT content of the supernatant fraction was about 25% of that of the total homogenate and significantly higher than that in 1, 7 and 21‐day‐old rats. In 1‐day‐old rats fasting caused an increase of 100% in the turnover, 50% in the content and no alteration in the subcellular distribution of brain 5‐HT, which suggests that under normal conditions 5‐HT stores may be filled near to capacity. After 5‐hydroxytryptophan administration, the 5‐HT content of the adult rat brain increased 3‐fold and that of the supernatant fraction to 35% of 5‐HT content of the total homogenate. In postnatal rats, the brain 5‐HT content rose to an adult level and the supernatant 5‐HT percentage to a markedly higher than adult level, probably because of the known higher than adult 5‐hydroxytryptophan decarboxylase activity of brain capillaries. Administration of tranylcypromine to adult rats caused a 2.6‐fold increase of brain 5‐HT content and a slight increase of the supernatant 5‐HT percentage. At various times after the administration of the MAO inhibitors (tranylcypromine or pargyline) and fasting to the 1‐day‐old rats, brain 5‐HT content increased 4, 5 and 7‐fold, respectively, and the supernatant 5‐HT rose consistently and, as in the adult, to about 30% of the 5‐HT content of the total homogenate. After pargyline following reserpine pretreatment, the 5‐HT content of the adult and 1‐day‐old rat brain increased to 2–3 times the control level and that of the supernatant fraction to about 40% of the 5‐HT content of the total homogenate. The adult values for 5‐HT in the particulate fraction of the 1‐day‐old rats after the drug treatments are in sharp contradiction to the low endogenous 5‐HT content and known lack of nerve terminals and synaptic vesicles in their brains, and suggest that after MAO inhibition brain 5‐HT neurons may bind the amine by some other mechanism than the Mg2+‐ATP‐dependent, reserpine‐sensitive granular storage.
DECREASED METABOLISM IN VIVO OF GLUCOSE INTO AMINO ACIDS OF THE BRAIN OF THIAMINE‐DEFICIENT RATS AFTER TREATMENT WITH PYRITHIAMINE
Authors: Gaitonde M. K. , Fayein N. A. , Johnson A. L.
Published: October 2006

Abstract— Thiamine deficiency produced by administration of pyrithiamine to rats maintained on a thiamine‐deficient diet resulted in a marked disturbance in amino acid and glucose levels of the brain.

In the two pyrithiamine‐treated groups of rats (Expt. A and Expt. B) there was a significant decrease in the levels of glutamate (23%, 9%) and aspartate (42%, 57%), and an increase in the levels of glycine (26%, 27%) in the brain, irrespective of whether the animals showed signs of paralysis (Expt. A) or not (Expt. B). as a result of thiamine deficiency. A significant decrease in the levels of γ‐aminobutyrate (22%) and serine (28%) in the brain was also observed in those pyrithiamine‐treated rats which showed signs of paralysis (Expt. A). Threonine content increased by 57% in Expt. A and 40% in Expt. B in the brain of pyrithiamine‐treated rats, but these changes were not statistically significant.

The utilization of [U‐14C]glucose into amino acids decreased and accumulation of glucose and [U‐14C]glucose increased significantly in the brain after injection of [U‐14C]glucose to pyrithiamine‐treated rats which showed abnormal neurological symptoms (Expt. A). The decrease in 14C‐content of amino acids was due to decreased conversion of [U‐14C]glucose into alanine, glutamate, glutamine, aspartate and γ‐aminobutyrate. The flux of [14C]glutamate into glutamine and γ‐aminobutyrate also decreased significantly only in the brain of animals paralysed on treatment with pyrithiamine.

The decrease in the labelling of, amino acids was attributed to a decrease in the activities of pyruvate dehydrogenase and α‐oxoglutarate dehydrogenase in the brain of pyrithiamine‐treated rats. The measurement of specific radioactivity of glucose, glucose‐6‐phosphate and lactate also indicated a decrease in the activities of glycolytic enzymes in the brain of pyrithiamine‐treated animals in Expt. A only. It was suggested that an alteration in the rate of oxidation in vivo of pyruvate in the brain of thiamine‐deficient rats is controlled by the glycolytic enzymes, probably at the hexokinase level.

The lack of neurotoxic effect and absence of significant decrease in the metabolism of [U‐14C]glucose in the brain of pyrithiamine‐treated animals in Expt. B were probably due to the fact that animals in Expt. B were older and weighed more than those in Expt. A, both at the start and the termination of the experiments.
ORGAN CULTURE OF THE RAT ADRENAL MEDULLA: A MODEL SYSTEM FOR THE STUDY OF TRANS‐SYNAPTIC ENZYME INDUCTION
Authors: Goodman R. , Otten U. , Thoenen H.
Published: October 2006

—It was the aim of the present study to develop organ culture conditions for the rat adrenal medulla which are representative for the in vivo situation. This is a prerequisite for studying the complex processes involved in trans‐synaptic enzyme induction. The processes of trans‐synaptic enzyme induction initiated in vivo by injecting 5 mg/kg of reserpine 2 h prior to the removal of the adrenal medulla, continued in this culture system and final levels of tyrosine hydroxylase were comparable to those seen in vivo. That these culture conditions are representative for the in vivo induction is also supported by the fact that transection of the splanchnic fibres supplying the adrenal medulla or administration of actinomycin D prior to reserpine abolished the rise in tyrosine hydroxylase activity not only in vivo, but also in culture.

The findings that high concentrations (0·29 mm) of corticosterone in the culture medium inhibited the increase in tyrosine hydroxylase activity caused by reserpine support the hypothesis that glucocorticoids act as modulatory agents in trans‐synaptic enzyme induction. This inhibition was exhibited only when corticosterone was added at the initiation of the culture period. If added 2 or 4 h after the beginning of the culture period there was little or no effect on the subsequent increase of tyrosine hydroxylase.
THE CHLORIDE CONTENT, ANION DEFICIT AND VOLUME OF SYNAPTOSOMES
Authors: Marchbanks R. M.
Published: October 2006

—The uptake of 36Cl− into incubated synaptosomes was found to reach a steady state within 30 min enabling estimates of the amount of intra‐synaptosomal chloride to be made. There was an excess in the total charge of sodium and potassium over that of chloride within the synaptosomes. This deficit of permeant anions is balanced within the synaptosome by negatively charged protein and other anions such as aspartate and phosphate. Their combined amount could be estimated from the magnitude of the anion deficit.

The net valency of the substances causing the anion deficit was determined by relating the ion content to the intra‐synaptosomal volume when metabolic activity was blocked. It was found to be similar to that of cerebral cortex tissue in vivo. The intra‐synaptosomal volume was found to change so that the osmolarity of the synaptosomal contents equalled the osmolarity of the incubation medium. A method of determining the intra‐synaptosomal volume by measuring the ion content is described. The results from this method are compared with those obtained using conventional space markers.
PURIFICATION AND PROPERTIES OF BRAIN N‐ACETYL‐β‐HEXOSAMINIDASE A
Authors: Aruna Rita M. , Basu Debkumar
Published: October 2006

—N‐Acetyl‐β‐hexosaminidase A was purified to homogeneity from human and monkey brains by the conventional procedures followed by concanavalin A–Sepharose affinity chromatography. The optimal activity was observed at pH 4·5 for both enzyme preparations with both the aglycones N‐acetylglucosamine and N‐acetylgalactosamine derivatives. The Km values for hexosaminidase A from monkey brain were 0·26 mm and 0·04 mm respectively for N‐acetylglucosamine and N‐acetylgalactosamine. Km values obtained for glucosamine and galactosamine derivatives for the human brain hexosaminidase A were of the same order. The glycoprotein nature of the enzymes was established by the affinity towards concanavalin A as well as by the presence of sialic acid, galactose, glucose, mannose and hexosamines in the enzyme molecule from monkey brain.
ACETYLCHOLINESTERASE ET BIOSYNTHESE DES PROTEINES DU GANGLION SYMPATHIQUE AU REPOS ET STIMULE1: ACETYLCHOLINESTERASE AND BIOSYNTHESIS OF PROTEINS IN THE RESTING AND STIMULATED SYMPATHETIC GANGLION1
Authors: Gisiger V. , Venkov L. , Gautron J.
Published: October 2006

—Des séparations sur gel de polyacrylamide ont permis d'établir la distribution électrophorétique des protéines, de l'incorporation d'acides aminés et de l'acétylcholinestérase (AChE; EC 3.1.1.7) du ganglion sympathique au repos et stimulé. Une étude conjointe d'histochimie ultrastructurale a montré que l'essentiel de l'activité acétylcholinestérasique des neurones sympathiques et des nerfs préganglionnaires est localisée dans le réticulum endoplasmique. Les molécules d'AChE du ganglion ont une faible mobilitéélectrophorétique, elles se répartissent en 3 bandes: une majeure et deux mineures. Le profil de radioactivité obtenu après marquage par la l‐[U‐14C]leucine se caractérise par la présence de 3 pics importants qui sont situés au début, au milieu et à la fin de l'électrophorégramme. Les bandes de protéines et le pic de radioactivité migrant dans le début du gel ainsi que la bande majeure d'AChE ne sont extraites qu'en présence de Triton X‐100. La zone de radioactivité contenant l'activité acétylcholinestérasique perd plus de 50% de sa radioactivité après 5 à 8 h de chasse du précurseur. La stimulation préganglionnaire à 16/s appliquée durant 1 à 4h abaisse d'environ 50% l'incorporation de la l‐[U‐14C]leucine dans les protéines migrant au début et à la fin de l'électrophorégramme. La radioactivité associée à la région des bandes d'AChE est diminuée de moitié par la stimulation.
A COMPARISON OF THYMIDYLATE SYNTHETASE ACTIVITIES FROM 5‐FLUORODEOXYURIDINE SENSITIVE AND RESISTANT VARIANTS OF MOUSE NEUROBLASTOMA1
Authors: Baskin F. , Rosenberg R. N.
Published: October 2006

Abstract— We have previously described a 5‐fluorodeoxyuridine (FUdR) resistant variant of mouse neuroblastoma possessing an 8‐fold elevation in methylenetetrahydrofolate: dUrd‐5′‐P C‐methyltransferase (EC2.1.1.b) [trivial name: thymidylate synthetase] specific activity relative to that of the sensitive parental clone. This increased specific activity is not associated with a change in cytoplasmic inhibitors or activators, a decreased degradation rate of the enzyme, or the synthesis of a new species with an increased Vmax, but appears to represent an increased synthesis of the enzyme species found in the sensitive parental clone. More resistant cell populations demonstrate even higher specific activities of this enzyme.

The enzymatic activities from both the FUdR sensitive and resistant cells have identical stabilities to sonication, freezing, heat, urea, and sodium dodecyl sulfate, are equally and strongly inhibited by 5‐fluorodeoxyuridine‐5′‐phosphate, and have the same affinity for the substrate 2′‐deoxyuridine‐5′‐phosphate (Km= 1·4 = 10−6m). Both are stimulated by the addition of mercaptans and partially protected from heat denaturation in the presence of substrate.

Unlike Don Chinese hamster cells (Conrad & Ruddle 1972) an actinomycin d pulse of neuroblastoma cells in monolayer culture did not increase the thymidylate synthetase specific activity. Mixed growth of FUdR sensitive and resistant cells produced only additive activities.
EFFECTS OF BOTULINUM AND TETANUS TOXINS ON CHOLINE ACETYLTRANSFERASE ACTIVITY IN SKELETAL MUSCLE IN THE MOUSE
Authors: Tonge D. A. , Gradidge T. J. , Marchbanks R. M.
Published: October 2006

Abstract— The effects of botulinum and tetanus toxins on the activity of choline acetyltransferase present in the motor nerve terminals of fast and slow skeletal muscle in the mouse were investigated. There was no change in the activities of choline acetyltransferase in either muscle after the injection of botulinum toxin but tetanus toxin caused a rise in the activity of the enzyme in fast muscle. Botulinum toxin is known to inhibit the release of acetylcholine and whilst neuromuscular transmission is blocked the motor nerves sprout and form new end‐plates. Tetanus toxin has been shown to cause hyperactivity of motor neurons. The nerve growth caused by the botulinum toxin did not result in increased choline acetyltransferase levels in the muscles, whereas the synaptic hyperactivity caused by tetanus was associated with increased enzyme levels.
CYCLIC NUCLEOTIDE PHOSPHODIESTERASE OF HUMAN CEREBROSPINAL FLUID
Authors: Hidaka H. , Shibuya M. , Asano T. , Hara F.
Published: October 2006

Abstract— Cyclic 3′,5′‐AMP (cAMP) and cyclic 3′,5′–GMP (cGMP) phosphodiesterase activities were found in human cerebrospinal fluid (CSF) using low substrate concentration (0.4μM). More rapid hydrolysis of cGMP than that of cAMP was observed in human CSF. However, cGMP hydrolytic activity of CSF was very much lower (0.3 pmol/min/ml CSF) than that of human cerebral cortex (33.7 nmol/min/g wet cortex). The pH optimum was found to be 8.0 (cGMP phosphodiesterase) and 7.5 (cAMP phosphodiesterase). The maximum stimulation of both cAMP and cGMP phosphodiesterase was achieved at 4 mM‐MgCl2. Cyclic AMP had relatively little effect on the hydrolysis of cGMP in CSF and the cortex, while cGMP inhibited hydrolysis of cAMP in both tissues. Snake venom was found to stimulate cAMP and cGMP phosphodiesterase activity of CSF, by 60% and 110% respectively. This stimulation by snake venom was also observed in the cortex phosphodiesterase, but was not observed in human plasma or thyroid phosphodiesterase. When CSF was applied to Sepharose 6B column, cGMP phosphodiesterase was separated into three different molecular forms. A plot of activity against substrate concentration using peak I (largest molecular size) revealed a high affinity (Km= 2.6μM) and a low affinity (Km= 100μM) for cAMP suggesting the existence of at least two molecular forms of the enzyme. On the other hand, using a cGMP as substrate the only one Km value (1.90 μm) was obtained. These Km values of CSF enzymes described above were close to those obtained from human cerebral cortex preparations. The enzyme under peak I corresponded to the cortex enzyme when judged from its molecular size and stimulation by snake venom. It seems likely from our results that at least a part of CSF phosphodiesterase originates from the central nervous system.
PROTEINS OF AXONAL TRANSPORT: INVESTIGATION OF SOLUBILITY CHARACTERISTICS AND BEHAVIOUR IN GEL FILTRATION
Authors: Karlsson J.‐O.
Published: October 2006

Abstract—

Rapid axonal transport of proteins in retinal ganglion cells of the rabbit was studied following intraocular injections of labelled amino acids. Approximately 10% of the transported radioactivity was found in the supernatant following homogenization and high‐speed centrifugation of the nerve terminal region. Relatively simple manipulations with ionic strength, pH and the presence of a chelating agent could solubilize an equivalent amount of radioactivity from the pellet. Lithium diiodosalicylate solubilized most rapidly transported membrane proteins. Gel filtration of readily soluble rapidly transported radioactivity gave a main macromolecular radioactive peak with an approximate mol. wt. of 500,000 dalton as determined on Sephadex G‐200. However, gel filtration on Sepharose CL‐6B gave a mol. wt. of about 160,000 for the same radioactive peak. SDS polyacrylamide gel electrophoresis of rapidly transported soluble proteins and fractions derived from these proteins via gel filtration and ion exchange chromatography revealed in all cases a very complex picture of labelled polypeptides. Thus rapid axonal transport of soluble proteins in this system seems to involve many different macro‐molecules
A METHOD FOR THE ASSAY OF CONJUGATED 3,4‐DIHYDROXYPHENYLGLYCOL, A MAJOR NORADRENALINE METABOLITE IN THE RAT BRAIN
Authors: Nielsen M. , Braestrup C.
Published: October 2006

Abstract—

We present the first published procedure for the measurement of endogenous conjugated 3,4‐dihydroxyphenylglycol (DOPEG) in the rat brain. Conjugated DOPEG is estimated from brain extracts after enzymic hydrolysis, isolation of hydrolysed DOPEG on alumina, methylation of DOPEG to 3‐methoxy‐4‐hydroxyphenylglycol (MOPEG) and gas chromatographic quantification of MOPEG. The level of conjugated DOPEG in the CNS of rats (65.7 ± 0.7 ng/g whole brain tissue corrected for recovery) almost equals the level of conjugated MOPEG. The sensitivity of the method is about 6 ng/g brain tissue. After inhibition of monoamine oxidase with clorgyline (30mg/kg) conjugated DOPEG and MOPEG both disappeared from the brain with a half‐life of about 1 h. Turnover calculations indicate that conjugated DOPEG and MOPEG are the two major noradrenaline end‐metabolites in the rat brain.

The method of estimating conjugated DOPEG also allows the measurement of noradrenaline, dopamine and total MOPEG in an extract from one half of a rat brain.
THE RELATIONSHIP BETWEEN ACETYLCHOLINE RELEASE FROM BRAIN SLICES AND THE ACETYLCHOLINE CONTENT OF SUBCELLULAR FRACTIONS PREPARED FROM BRAIN
Authors: Salehmoghaddam S. H. , Collier B.
Published: October 2006

Abstract— Acetylcholine (ACh) release from sliced cerebral cortex of rats was measured when the tissue was incubated in a high K+ (46 mm) medium containing eserine. In the absence of hemicholinium (HC‐3), ACh release was well maintained, but in the presence of HC‐3, ACh release declined within 15–20 min. Subcellular fractions representing nerve‐ending free (cytoplasmic) ACh and nerve‐ending bound ACh were prepared from slices that had been stimulated to release ACh in the presence of HC‐3. Both nerve‐ending stores of ACh were depleted when their content was compared to tissue that had not been stimulated and there was no demonstrable difference in the rate of depletion of either of the two fractions. Stimulating slices with K+ in the absence of HC‐3 also depleted cytoplasmic and vesicle‐bound ACh. It is concluded that, under these experimental conditions, both nerve ending stores of ACh are available for release and that, in the absence of HC‐3, ACh synthesis can maintain ACh release, but cannot maintain tissue ACh content.
INCORPORATION OF [1‐14C]OLEIC ACID AND [1‐14C]ARACHIDONIC ACID INTO LIPIDS IN THE SUBCELLULAR FRACTIONS OF MOUSE BRAIN
Authors: Sun Grace Y. , Yau T. M.
Published: October 2006

Abstract— The distribution of radioactivity among lipids of subcellular membrane fractions was examined after intracerebral injections of [1‐14C]oleic and [1‐14C]arachidonic acids. Labelled free fatty acids were distributed among the synaptosomal‐rich, microsomal, myelin and cytosol fractions at 1 min after injection. However, incorporation of the fatty acids into phospholipids and trïacylglycerols after pulse labelling occurred mainly in the microsomal and synaptosomal‐rich fractions. With both types of labelled precursors, there was a higher percentage of radioactivity of diacyl‐glycerophosphoryl‐inositols in the synaptosomal‐rich fraction as compared to the microsomal fraction. Radioactivity of [1‐14C]oleic acid was effectively incorporated into the triacylglycerols in the microsomal fraction whereas radioactivity of the [1‐14C]arachidonic acid was preferentially incorporated into the diacyl‐glycerophosphorylinositols in the synaptosomal‐rich fraction. Result of the study indicates that synaptosomal‐rich fraction in brain is able to metabolize long chain free fatty acids in vivo and to incorporate these precursors into the membrane phosphoglycerides.
FACTORS REQUIRED FOR Ca‐SENSITIVE ACETYLCHOLINE RELEASE FROM CRUDE SYNAPTIC VESICLES
Authors: Hata F. , Kuo C. H. , Matsuda T. , Yoshida H.
Published: October 2006

Abstract— Studies were made on intracellular factors required for the release of ACh from crude synaptic vesicles prepared from rat brain. A factor stimulating ACh release in the presence of calcium ions was found in the cell sap.

Cell sap obtained by hypotonic shock of a crude mitochondrial fraction stimulated ACh release from the synaptic vesicles in the presence of ATP and magnesium ions. Calcium ions were essential for its effect and the optimum concentration of calcium was about 10−4m. The stimulatory factor in cell sap passed through a cellulose or collodion membrane or ultrafiltration membrane UM 10, but not through that of an ultrafiltration membrane UM 05. The factor was not affected by trypsin or α‐chymotrypsin, but was inactivated by pronase or carboxypeptidase‐A. Thus it seemed to be a peptide‐like substance with a rather low molecular weight. Cyclic‐AMP, cyclic‐GMP, colchicine and vinblastne did not affect ACh release under our experimental conditions.
THE EFFECT OF CORDYCEPIN ON THE APPEARANCE OF [3H]RNA IN THE GOLDFISH OPTIC TECTUM FOLLOWING INTRAOCULAR INJECTION OF [3H]URIDINE
Authors: Ingoglia N. A. , Sellin L. C. , Lindquist T. D.
Published: October 2006

Abstract— Although biochemical and electron microscopic evidence has shown that RNA molecules may be found within axons, the origin of this RNA is not known. In order to determine if the RNA found in axons is synthesized in the nerve cell body and axonally transported, we have studied the effect of the RNA inhibitor cordycepin (3′‐deoxyadenosine) on the retinal synthesis and axonal migration of radioactive RNA. Ten μg of cordycepin was injected into the right eye of 11 fish and 3 h later [3H]uridine was injected into the same eye. Twelve control fish were injected with [3H]uridine only and all fish were sacrificed 6 days later. Results of RNA extraction of retina and tecta showed that cordycepin decreased retinal RNA synthesis by approx 24%, while inhibiting the amount of [3H]RNA appearing in the contralateral tectum by 74%. Since the transport of RNA precursors was depressed by only 50%, (significantly different from the effect on RNA, P < 0.01) it seems unlikely that the action of cordycepin in decreasing tectal [3H]RNA levels was due solely to a decrease in the availability of labeled precursors for tectal RNA synthesis.

For the purpose of blocking tectal RNA synthesis, 200 μg of cordycepin was injected intracranially several days after the intraocular injection of [3H]uridine. This route of cordycepin administration failed to significantly block the appearance of [3H]RNA in the tectum, suggesting that at least some of the [3H]RNA in the tectum was synthesized before arrival in the tectum itself.

To be sure that cordycepin itself was not being transported, we injected cordycepin into the right eye of fish and 5 days later, injected fish intracranially with [3H]uridine. Autoradiograms were prepared and grains were counted over the fiber layers of left (experimental) and right (control) tecta. No significant difference was observed in the number of grains of left vs right tecta indicating that cordycepin itself is not axonally transported.

These experiments support earlier findings from our laboratory which suggest that RNA may be axonally transported in goldfish optic fibers.
PROPERTIES OF THE UPTAKE AND RELEASE OF GLUTAMIC ACID BY SYNAPTOSOMES FROM RAT CEREBRAL CORTEX
Authors: Takagaki G.
Published: October 2006

Abstract– (1) The uptake and release of glutamic acid by guinea‐pig cerebral cortex slices and rat synaptosomal fractions were studied, comparing the naturally occurring l‐ and non‐natural d‐isomers. Negligible metabolism of d‐glutamic acid was observed in the slices. (2) Whereas in the cerebral slices the accumulation of glutamic acid was almost the same for the two isomers, d‐glutamic acid was accumulated into the synaptosomal fraction at a markedly lower rate than was the L‐isomer. (3) The uptake systems for d‐isomer into the slices and synaptosomal fraction were found to be of single component, in contrast with the two component systems, high and low affinity components, for the uptake of l‐glutamic acid. The apparent Km values for the uptake of d‐glutamic acid into the slices and synaptosomal fraction were comparable with those reported for the low affinity components for l‐isomer. The uptake systems for d‐glutamic acid were dependent on the presence of Na+ ions in the medium, like those for l‐glutamic acid and GABA. (4) The evoked release of radioactive preloaded d‐glutamic acid was observed both from the slices and synaptosomal fraction following stimulation by high K+ ions in the medium. From these observations, it is evident that the evoked release of an amino acid by depolarization in vitro is not necessarily accompanied by a high affinity uptake process. (5) The uptake of l‐glutamic acid, expecially into the synaptosomal fraction, was highly resistant to ouabain. On the other hand, the uptake rate of d‐glutamic acid and GABA into the synaptosomal fraction was inhibited by varying concentrations of ouabain in accordance with the inhibition for brain Na‐K ATPase. (6) The uptake of l‐glutamic acid into subfractions of the P2 fraction was studied in relation to the distribution of the ‘synaptosomal marker enzymes’. An attempt to correlate the activities of enzymes of glutamic acid metabolism with the uptake of l‐glutamic acid into the synaptosomal fraction from various parts of brain was unsuccessful. The high affinity uptake of l‐glutamic acid was found to be very active in the synaptosomal fraction from any part of brain examined.
THE NON‐SYNCHRONOUS SYNTHESIS OF MYELIN COMPONENTS DURING EARLY STAGES OF MYELINATION IN THE RAT OPTIC NERVE1
Authors: Detering Nancy K. , Wells M. A.
Published: October 2006

—Analysis of lipids and proteins in whole optic nerves during initial stages of myelination indicate a sequential deposition of myelin components. During this period sulfatide levels increase from 4 nmol/pair of nerves at 9 days to 29 nmol/pair of nerves at 21 days. Cerebrosides are not detected until the 12th day and attain a level of 46 nmol/pair of nerves in the 21‐day old rat. Plasma‐logen values increase from 2.1 to 31 nmol/pair of nerves and cholesterol values from 12 to 158 nmol/pair of nerves between 9 and 21 days. High molecular weight proteins are present in samples from 9‐day old rats analyzed by discontinuous sodium dodecyl sulphate‐polyacrylamide gel electrophoresis. Under identical conditions myelin basic proteins are first observed in the 10 day sample, and the proteolipid protein is first detected in the 12 day sample. The 2′, 3′‐cyclic nucleotide 3′‐phosphohydrolase activity increases from 1.13 to 5.50 μmol/min per mg protein between 9 and 21 days.
THE BINDING OF ACETYLCHOLINE TO SYNAPTIC VESICLES FROM TORPEDO CALIFORNICA ELECTROPLAX
Authors: Mattson M. E. , O'Brien R. D.
Published: October 2006

Abstract— The in vitro uptake of exogenous acetylcholine by isolated presynaptic vesicles has been demonstrated in a new system. A preparation of vesicles from Torpedo californica electroplax was developed in which acetylcholinesterase and acetylcholine receptor activity were blocked. The vesicles bound acetylcholine with Kd 1.58 μM, the maximum amount bound being 26 pmol per g of original tissue, or 52 molecules per vesicle. Nicotinic drugs blocked binding, but muscarinic and noncholinergic drugs did not. The relative potency of nicotinic drugs differed greatly from their potency on Torpedo receptor. Sephadex chromatography showed that 26% of the binding was irreversible. The relationship of the binding to acetylcholine uptake and storage was discussed.
POSTNATAL ALTERATIONS IN EFFECTS OF POTASSIUM ON UPTAKE AND RELEASE OF GLUTAMATE AND GABA IN RAT BRAIN CORTEX SLICES
Authors: Schousboe A. , Lisy V. , Hertz L.
Published: October 2006

Abstract—

The uptake and release of glutamate and of GABA, as well as the effect of high potassium concentrations (35 or 80 mM) hereupon, were studied by aid of 14C‐labelled amino acids in brain cortex slices from rats of different ages between birth and adulthood. Both the extent of the uptake (i.e. the tissue/medium ratio of 14C at, or close to, equilibrium) and the rate of uptake (i.e. the tissue/ medium ratio of 14C after short (5 min) incubation periods) increased with age. Differences were, however, found between glutamate and GABA, and the extent of the GABA uptake had a distinct maximum during the second postnatal week. At all ages, high concentrations of potassium caused a decrease in the rate of GABA uptake but were without effect on the rate with which glutamate was taken up. The release of the two amino acids occurred with approximately the same half‐time (50 min) in slices from animals of at least 14 days of age. Before that time the release of glutamate was somewhat faster, whereas that of GABA was much slower, especially during the first postnatal week (half‐time 90 min). The ontogenetic alterations in the effect of excess potassium were complex and varied both between the two potassium concentrations used and between the two amino acids. The results are thus compatible with the existence of different transport systems for the two amino acids, They also suggest that glutamate may exert other functions in addition to its role as a putative transmitter.
INHIBITION OF ACETYLCHOLINE SYNTHESIS AND OF CARBOHYDRATE UTILIZATION BY MAPLE‐SYRUP‐URINE DISEASE METABOLITES
Authors: Gibson G. E. , Blass J. P.
Published: October 2006

The branched‐chain 2‐oxo acids which accumulate in maple‐syrup‐urine disease inhibited the production of acetylcholine and of lipids, proteins, nucleic acids and of CO2. in sliced adult rat brains incubated with [U‐14C] glucose. Inhibition of the biosynthetic reactions was proportional to the inhibition of CO2 production, even though the flux of radioactivity into the biosynthetic products was less than 2% of that to CO2.

The oxo acids reduced the production of 14CO2, from [U‐14C] glucose and from [2‐14C]pyruvic acid more than from [1‐14C]pyruvic acid in sliced brains. They inhibited the solubilized oxoglutarate dehydrogenase complex more than they did the solubilized pyruvate dehydrogenase complex. Valine and isoleucine, which also accumulate in maple‐syrup‐urine disease, inhibited pyruvate kinase from rat brain allosterically. Quantitative comparison of the effects of the disease metabolites on cell‐free systems with their effects on fluxes in intact cells indicated that the inhibition of oxoglutarate dehydrogenase appeared to be functionally significant. The residual activities of the other enzymes studied were adequate to support the normal flux of carbohydrates.

The oxo acids were effective at concentrations within the range reported to occur in patients with maple‐syrup‐urine disease. The effects on biosyntheses including that of acetylcholine would be expected to impair brain development and function and could be important in the development of brain disease in the patients. In contrast to the results with metabolites from maple‐syrup‐urine disease, metabolites which accumulate in phenylketonuria (phenylalanine and 2‐oxo‐3‐phenylpropionic acid) did not inhibit carbohydrate utilization or the biosynthetic reactions studied, under the conditions of these experiments.
DISTRIBUTION AND OPTICAL ACTIVITY OF THE BASIC PROTEIN IN BOVINE PERIPHERAL NERVE MYELIN
Authors: Uyemura K. , Kato‐Yamanaka T. , Kitamura K.
Published: October 2006

Abstract— Antiserum to BF protein isolated from bovine spinal roots has been used to study the distribution of the protein in other species and tissues.

Significant amounts of protein could be demonstrated in bovine, pig and rabbit peripheral nerve myelin. It was, however, scarcely detectable in guinea pig peripheral nerve myelin. There was BF protein in rabbit spinal cord as well as in peripheral nerve, but little or no BF protein in the liver, kidney, muscle or brain. BF protein in bovine spinal cord was localized in the myelin. The ratio of the BF protein to the encephalitogenic protein in the spinal cord myelin was around 0.15:1.0. BF protein was extractable from peripheral nerve myelin by saline as well as by acid solutions.

The circular dichroism spectrum of the BF protein in aqueous solution suggested that this protein contained a very large amount of β‐structure. This structure was not considered to be the result of acid denaturation because the protein purified from the saline extract of peripheral nerve also showed a similar spectrum.
CYCLIC NUCLEOTIDE ACCUMULATION IN VITRO IN THE CEREBELLUM OF ‘NERVOUS’ NEUROLOGICALLY MUTANT MICE
Authors: Schmidt M. J. , Nadi N. S.
Published: October 2006

Abstract— Slices of cerebellum from Purkinje cell‐deficient, neurologically mutant ‘nervous’ mice or normal littermates synthesized cyclic AMP and cyclic GMP during in vitro incubations. Resting levels of cyclic AMP were the same in the two groups, but accumulations in the presence of kainic acid, a glutamic acid analogue, or norepinephrine were significantly greater in the ‘nervous’ mice. Resting levels of cyclic GMP were lower in the ‘nervous’ mice, but the elevations produced by kainic acid were the same in both groups. Adenylate and guanylate cyclase activities in the cerebellum were not affected by the mutation. These findings indicate that cyclic nucleotide synthesis in the cerebellum does not occur solely in the Purkinje cell population.