bluuebunny/crossref_metadata_2025_split huggingface dataset:
SOLUBILIZATION AND PHYSICOCHEMICAL CHARACTERIZATION OF RAT BRAIN ACETYLCHOLINESTERASE: DEVELOPMENT AND MATURATION OF ITS MOLECULAR FORMS
Authors: Rieger F. , Vigny M. 
Published: October 2006

Abstract— We have solubilized two active molecular forms of AChE from rat brain and compared them to the molecular forms solubilized from rat muscle. One of these forms, in muscle, as well as in brain, is easy to solubilize without detergent (ES form–apparent sedimentation coefficient without detergent: 4.6s); the other is hard to solubilize and we obtained a nearly total solubilization only in the presence of detergent (HS form–apparent sedimentation coefficient in presence of detergent: 10.3s). These two molecular forms are glycoprotein in nature. They interact with detergent (Triton X‐100), as demonstrated by a comparison of their hydrodynamic parameters (determined by sucrose gradient centrifugation and molecular filtration) in the presence and absence of detergent. In the absence of detergent, their molecular weights are 115,000 for the ES form and 435,000 for the HS form. We did not find the molecular form in brain which seems to be specific to the muscle endplate region. at any stage of its development (EP form–solubilized by detergent–apparent s value in presence of detergent: 16.2s).During development or maturation of the rat brain, the relative proportion of the HS form to the ES form increases; its absolute amount also increases (by more than a factor of 7 during the first month after birth). The ES form seems to be established at its adult level at the time of birth, before the large increase in the HS form. The proportion of each form in the adult rat brain remains constant: 90% of the total activity is represented by the HS form.
STUDIES ON THE UPTAKE AND RELEASE OF RADIOACTIVE TAURINE BY THE FROG RETINA
Authors: Kennedy A. J. , Voaden M. J. 
Published: October 2006

Abstract— Taurine is taken up into the frog retina by active, sodium dependent, temperature sensitive systems that show both high and low affinity for the amino acid (Kmabout 50 μm and 2 mm respectively). Autoradiographs from retinae incubated in radioactively labelled taurine showed heavy grain density over cell bodies in the position of amacrine interneurones and over specific strata in the inner synaptic layer of the tissue. Photoreceptor cells were also labelled.Taurine, once accumulated by the frog retina, is not lost during the incubation and is only slowly metabolised. Electrical stimulation caused taurine release above the level of spontaneous efflux but light or depolarisation of the tissue with 40mm‐potassium chloride did not.
AMINO ACIDS IN ‘LIGHT’ AND ‘HEAVY’ SYNAPTOSOME FRACTIONS FROM RAT OLFACTORY LOBES AND THEIR RELEASE BY ELECTRICAL STIMULATION
Authors: Osborne R. H. , Duce I. R. , Keen P. 
Published: October 2006

Abstract– ‘Light’ and ‘heavy’ isolated nerve‐ending fractions were prepared from rat olfactory lobes. The ‘light’ fraction contained small nerve‐endings and the ‘heavy’ fraction large simple nerve‐endings and also complex profiles consisting of two or sometimes three conjoined sacs. Both fractions respired linearly over a 40‐min incubation period. Although neither was enriched relative to protein in any of the amino acids examined, when the content of an amino acid was expressed as a percentage of the sum of the amino acids measured in that fraction, aspartate was found to be relatively concentrated in both fractions and GABA in the ‘heavy’ fraction only.When synaptosome beds prepared from these fractions were incubated in Krebs‐bicarbonate medium aspartate, glutamate and GABA were specifically retained in the beds, possibly due to re‐uptake of endogenous amino acid, and it is suggested that this may prove a useful test for the presence of a high‐affinity uptake system for an endogenous substance. Electrical stimulation of the beds caused a selective release of glutamate, aspartate and GABA. The possibility that any of these three amino acids may have a neurotransmitter function in the olfactory lobe is discussed.
GLUCOCORTICOIDS AS A REGULATORY FACTOR FOR BRAIN TRYPTOPHAN HYDROXYLASE
Authors: Sze P. Y. , Neckers L. , Towle A. C. 
Published: October 2006

Abstract—The normal developmental rise of tryptophan hydroxylase levels in neonatal rat brain was blocked by adrenalectomy. Similarly, adrenalectomy prevented the rescrpine‐induced elevation of tryptophan hydroxylase activity in brain stem of adult mice. In both cases, the effects of adrenalectomy could be reversed by replacement injections of corticosterone. Repeated injections of corticosterone (5 mg/kg daily) in fact induced a rise of brain tryptophan hydroxylase levels in neonatal brain. However, neither adrenalectomy nor repeated injections of large doses of the hormone (20 mg/kg, daily) was found to be effective in affecting the normal enzyme levels in adult brain. Apparent Km of the enzyme for substrate was unchanged by corticosterone in vivo or in vitro. These results indicate that glucocorticoids have a significant role in the regulation of brain tryptophan hydroxylase: possibly as an inducing signal during neonatal development and as a permissive factor at adult age.
HISTAMINE SYNTHESIZING AFFERENTS TO THE HIPPOCAMPAL REGION
Authors: Barbin G. , Garbarg M. , Schwartz J.‐C. , Storm‐Mathisen J. 
Published: October 2006

Abstract—Histidine decarboxylase activity is found in all parts of the hippocampal formation (subiculum, CA1, CA3 and area dentata), and a major portion of the enzyme is localized in a subcellular fraction containing the nerve terminal particles. The almost complete disppearance of HD (and histamine) after deafferentation of the hippocampal formation suggests that histamine synthesis in this region resides in terminals of extrinsic fibres. The results after selective lesions indicate that these alleged histaminergic fibres enter the hippocampus, like the monaminergic fibres, through a dorsal route (comprising fimbria, fornix superior and cingulum) as well as through a ventral route (via the amygdaloid area). The former was tentatively estimated to represent about 60% of the total hippocampal supply of alleged histaminergic fibres.
AMINE FORMATION FROM l‐TRYPTOPHAN IN BRAIN SLICES
Authors: Weil‐Malherbe H. 
Published: October 2006

Abstract— Slices from four areas of guinea‐pig brain (hypothalamus, corpus striatum, median ponsmedulla and cerebral cortex) were incubated with concentrations of l‐[3‐14C]tryptophan varying from 20 to 300 μm. in the presence of 5 × 10‐5m‐pargyline. The formation of tryptamine and serotonin was studied.Serotonin synthesis reached its highest level at a concentration of approx 80 μm‐tryptophan in all 4 brain areas. Activity was high in pons‐medulla and hypothalamus but only about one third as high in corpus striatum and cortex.Tryptamine formation continued to increase within the concentration range of tryptophan used. Activity was high in corpus striatum where, at 300 μm‐tryptophan, tryptamine formation exceeded serotonin formation, but was low in cortex and intermediate in pons‐medulla and hypothalamus.The possible formation of kynuramine and 5‐hydroxykynuramine was also investigated. No evidence was obtained for the formation of 5‐hydroxykynuramine. Traces of radioactivity were found corresponding to kynuramine, but these were insufficient to establish its formation with certainty. If formed. the rate of kynuramine synthesis did not exceed 2% of the combined formation of serotonin and tryptamine.
CHOLINE ACETYLTRANSFERASE–EVIDENCE FOR ACETYL TRANSFER BY A HISTIDINE RESIDUE
Authors: Malthe‐Sorenssen D. 
Published: October 2006

Abstract— Choline acetyltransferase from bovine brain has been extensively purified to a specific activity of 2.5 μmol ACh/min mg protein. Attempts to isolate an acetyl enzyme intermediate after incubation of the enzyme with [1‐14C]acetyl‐CoA were unsuccessful. Such an intermediate could only be isolated using a 30‐fold less purified enzyme preparation. The protein, binding 14C in this preparation, did not correspond to choline acetyltransferase as shown by disc‐electrophoresis. The highly purified enzyme could, however, be labelled when choline acetyltransferase was immobilized on a mercuribenzoate sepharose gel and incubated with [1‐14C]acetyl‐CoA. Subsequently, the immobilized labelled enzyme or the labelled enzyme which had been released by cysteine from the gel. formed ACh after incubation with choline. The labelling and the following formation of [14C]ACh was pH dependent.Masking htstidine residues of the enzyme with diethylpyrocarbonate almost abolished the labelling of the immobilized enzyme and completely abolished the formation of [14C]ACh. Enzyme inhibited with 5.5′‐dithiobis(2‐nitrobenzoate) was partially reactivated when the thionitrobenzoatederivative was cleaved by KCN treatment to a thiocyanatederivalive. A reaction mechanism for ChAT is proposed based on the present data.
SLOW AXONAL TRANSPORT OF LABELLED PROTEINS IN SENSORY FIBRES OF RABBIT VAGUS NERVE
Authors: Mclean. W. G. , Frizell M. , Sjostrand J. 
Published: October 2006

AbstractBoth rapid (415 mm/day) and slow (24 mm/day) rates of axonal transport of proteins were found in sensory fibres of rabbit vagus nerve after injection of [3H]leucine into the nodose ganglion in vivo. The slow phase of transport was dependent on contact between the cell bodies and the nerve trunk, and did not continue under in vivro conditions. The results suggest some difference between the mechanisms of fast and slow transport.
DISTRIBUTION OF FOUR POTENTIAL TRANSMITTER AMINO ACIDS IN MONKEY RETINA
Authors: Berger Sosamma J. , McDaniel M. L. , Carter Joyce G. , Lowry O. H. 
Published: October 2006

Abstract—Discrete layers from frozen dried sections of Rhesus monkey retina were analyzed for each of four amino acids. Peak levels of glycine were found near the border of the inner nuclear and inner reticular layers, and were high throughout these two layers. The levels were less than 50% of the peak in the adjacent ganglion cells and outer reticular layers and fell to very low levels elsewhere. GABA was much more sharply restricted to the inner reticular layer and fell off on both sides to levels of 10% or less of the peak in the fiber and photoreceptor cell layers. Glutamate and aspartate were highest in the ganglion cell layer. On a lipid‐free dry weight basis the peak aspartate level was about twice that of brain. Moderately high levels of both aspartate and glutamate were found in the inner reticular and fiber layers. Elsewhere the levels ranged from 20 to 50% of the peak, and both amino acids were relatively low in optic nerve. The amino acid distributions are compatible with a transmitter function for GABA in amacrine cells and for glycine in horizontal and amacrine cells. Glutamate and aspartate may be especially high in Müller fibers, ganglion cells or both.
CALCIUM‐INDUCED RELEASE OF γ‐AMINOBUTYRIC ACID FROM SYNAPTOSOMES: EFFECTS OF TRANQUILIZER DRUGS
Authors: OLSEN R. W. , LAMAR E. E. , BAYLESS J. D. 
Published: October 2006

Abstract—Efflux of preloaded radioactive gamma‐aminobutyric acid (GABA) from mouse brain fractions enriched in synaptosomes could be significantly and reproducibly increased by switching from Ca2+‐free wash solution to one containing 2 mM‐Ca2+. With a filtration apparatus equipped for simultaneous buffer changes of eight samples, effects of various drugs on Ca2+‐dependent and Ca2+‐independent efflux of GABA were studied. Several membrane‐perturbing agents, including imipramine and neuroleptics like haloperidol and chlorpromazine, at 1 μM, potently inhibited Ca2+‐dependent GABA release. Benzodiazepine drugs similarly inhibited Ca2+‐dependent efflux, but also under appropriate conditions, enhanced Ca2+‐independent efflux. Stimulation of Ca2+‐independent efflux was observed with nonradioactive GABA and with GABA analogues which inhibit GABA transport, reflecting exchange of GABA via the high‐affinity transport system. Diazepam was found to inhibit GABA transport (non‐competitively; I50, 50 μM); effects on the transport system might be related to observations of potentiated GABA action and anti‐convulsant effects of this drug.
STUDIES ON INCREASED ACID HYDROLASE ACTIVITIES IN DENERVATED MUSCLE
Authors: MASKREY P. , PLUSKAL M. G. , HARRIS J. B. , PENNINGTON R. J. T. 
Published: October 2006

Abstract—Denervation of rat hemidiaphragm led to large increases in the activity of acid proteinase, cathepsin B1 and β‐glucuronidase in the muscle. The increases were not confined to the endplate regions of the muscle. Mononuclear cells extracted from normal and denervated extensor digitorum longus and diaphragm muscles contained only a small proportion of the acid proteinase and cathepsin B1 activities in the muscle. Actinomycin D, but not methotrexate, prevented the increase in acid proteinase and cathepsin B1 normally resulting from denervation. Brij/58 increased acid proteinase activity to a smaller extent in the denervated muscle than in the control. The length of the distal nerve stump remaining after denervation influenced the enzyme increases, but acid proteinase and cathepsin B1 appeared to be affected differently. The significance of the post‐denervation increase in hydrolase activities is still unknown.
ON THE RELATIONSHIP BETWEEN [3H]CHOLINE UPTAKE ACTIVATION AND [3H]ACETYLCHOLINE RELEASE
Authors: MURRIN L. C. , DHAVEN R. N. , KUHAR M. J. 
Published: October 2006

Abstract—The depolarization‐induced, calcium‐dependent release of [3H]ACh from hippocampal synaptosomes was studied in a superfusion system. Release increased, with increasing depolarization. Barium and strontium effectively substituted for calcium during the depolarization, but magnesium inhibited the release. Releasable [3H]ACh is derived from the sodium‐dependent component of the [3H]choline uptake which points out the physiologic importance of sodium‐dependent choline transport. It is concluded that [3H]ACh release in this system has the same properties as neurotransmitter release in many other systems.Previous studies have shown that treatments which alter the activity of cholinergic neurons in vivo result in parallel changes in sodium‐dependent choline uptake in vitro. When synaptosomes were utilized from animals treated to reduce cholinergic activity, there was a reduced release following the reduced uptake. Conversely, when synaptosomes were taken from animals treated to increase sodium‐dependent choline uptake, there was an increase in the release. It is concluded that the changes in sodium‐dependent choline uptake in vitro consequent to changes in neuronal activity in vivo result in parallel changes in releasable ACh.A comparison was made between the effect of a number of ions and agents on release and their effect on the in vitro, depolarization‐induced activation of sodium‐dependent choline uptake. Barium and strontium, ions which substitute for calcium in the release process, support the in vitro activation of uptake. Vinblastine and Bay a 1040, compounds which block release, prevented the in vitro activation of sodium‐dependent choline uptake. However, magnesium blocked release in a dose‐dependent manner, but did not block the activation of uptake in vitro. Rather, magnesium substituted for calcium and supported the activation of uptake in a dose‐dependent fashion. It is concluded that acetylcholine release is not necessary for the activation of choline uptake.
THE TOXIC EFFECTS OF TRIALKYLTIN COMPOUNDS ON NERVE AND MUSCLE
Authors: TAN L. P. , NG M. L. 
Published: October 2006

Abstract—The toxicity of trimethyltin chloride and triethyltin sulphate on animal tissues was assessed by their effects on isolated phrenic nerve‐diaphragm preparations. Studies by electron microscopy show that the inhibitory effects of these compounds on the muscular contractility of this tissue are associated with (a) the disruption of mitochondria and disorganisation of muscle fibres and (b) the depletion of neuromicrotubules in the axons of nerves innervating the muscle. The neurotoxie effect of triethyltin sulphate on neuromicrotubules is further substantiated by its inhibition (in a concentration‐dependent manner) of the specific colchicine‐binding activity of the crude and purified tubulin preparations derived from brain tissue. In addition, both triethyltin sulphate and trimethyltin chloride at a concentration greater than 100 μM completely prevent the normal in vitro assembly of microtubules from tubulin.
THE ACETYLCHOLINE RECEPTOR OF THE ADRENAL MEDULLA1
Authors: Wilson S. P. , Kirshner N. 
Published: October 2006

Abstract— The acetylcholine receptor of the bovine adrenal medulla was studied by specific binding of [1251]α‐bungarotoxin to membrane fractions and by perfusion of the isolated gland. The subcellular distribution of the acetylcholine receptor paralleled the distribution of the plasma membrane markers, acetylcholinesterase and calciumstimulated ATPase. The dissociation constant for the binding of α‐bungarotoxin to a purified plasma membrane fraction was calculated from Scatchard plots to be 1.6 nM, with a concentration of 190 fmol of binding sites/mg of membrane protein. Correcting for recovery, this corresponds to 0.9 pmol acetylcholine receptor/g adrenal medulla. In decreasing order of effectiveness, d‐tubocurarine, nicotine, acetylcholine, carbamylcholine, acetate plus choline, decamethonium, atropine and hexamethonium inhibited binding of α‐bungarotoxin.Perfusion experiments showed the acetylcholine receptor to be entirely nicotinic. Stimulation by nicotine was inhibited by atropine and decamethonium, as well as by hexamethonium. Calculated dissociation constants for these antagonist‐receptor interactions were in the range of 1 to 3 × 10−5 m. α‐Bungarotoxin failed to inhibit nicotine‐stimulated catecholamine release in the perfused adrenal, most likely because of its limited diffusion into the gland.
ON THE UPTAKE OF INOSITOL BY RAT BRAIN SYNAPTOSOMES
Authors: Warfield Anna , Hwang Shing Mei , Segal Stanton 
Published: October 2006

AbstractThe uptake of inositol by rat brain synaptosomes occurs via an unsaturable process that even at substrate concentrations as low as 1 μM is unable to achieve a concentration gradient indicative of active transport. Dinitrophenol, ouabain and cytochalasin B did not affect uptake of the cyclitol. The data indicate that inositol uptake by rat synaptosomes occurs by diffusion or by a system with an affinity so low it is difficult to discern. The low capacity, saturable inositol uptake system observed in rabbit brain slices may reflect a species difference or uptake by elements of the slice other than neuronal membranes.
THE BINDING OF [3H]MEPYRAMINE TO HISTAMINE H1 RECEPTORS IN GUINEA‐PIG BRAIN
Authors: Hill S. J. , Emson P. C. , Young J. M. 
Published: October 2006

AbstractThe promethazine‐sensitive binding of [3H]mepyramine to a membrane fraction from guinea‐pig whole brain is saturable with a dissociation constant of 1.7 × 10‐9M. The maximum amount of [3H]mepyramine binding varied widely between preparations, range 122–365 pmol/g protein, with a mean value of 227 ± 52 pmol/g protein. The inhibition of [3H]mepyramine binding by a number of drugs correlated closely with their potency as histamine H1 antagonists. (+) Chlorpheniramine was 240‐fold more potent as an inhibitor of [3H]mepyramine binding than (‐)‐chlorpheniramine. All antagonists inhibited the binding of [3H]mepyramine to the same extent, but the Hill coefficients characterising the inhibition curves did not all approximate to unity, the value expected for a simple antagonist‐receptor equilibrium. The distribution of histamine H1 receptors, defined by the promethazine‐sensitive binding of [3H]mepyramine, in 11 different brain regions was uneven with the largest amounts in cerebellum, superior and inferior colliculus and hypothalamus and the smallest in caudate nucleus, brain stem and spinal cord.
A NEW MATHEMATICAL APPROACH TO THE METABOLISM OF [14C]GLUCOSE, WITH APPLICATIONS TO SENSORY GANGLIA OF CHICKEN EMBRYOS1
Authors: Larrabee Martin G. 
Published: October 2006

Abstract— The available models of carbohydrate metabolism are not suitable for analysis of experiments on dorsal root ganglia of chicken embryos because they assume that certain products of the pentose cycle mix freely with those of glycolysis, which appears not to be true in this tissue, and because full isotopic equilibration, needed before the start of measurements, is not achieved while the excised ganglia are reasonably fresh. Therefore, new equations were developed which assume only a steady state of relevant metabolic intermediates and make use of the process of isotopic equilibration as a source of information. It is also assumed that an initially unknown but calculable fraction of the products of each pentose cycle re‐enters the next cycle, the remainder leaking either to glycolysis or to the incubation medium. From measurements of the time course of output of labelled CO2 in the presence of [1‐14C]‐ and [6‐14C]glucose and the incorporation and release in lactate of labelled C from [l‐14C]glucose, the equations permit the estimation of many features of carbohydrate metabolism, such as the partitioning of material between the pentose cycle and glycolysis, the partitioning of CO2 output between the pentose and citric acid cycles, the partitioning of the products of glycolysis between CO2 and other destinations, such as lactate, and the degree of recycling from one pentose cycle into the next. In addition, the time course of labelled CO2 output from [2‐14C]glucose can be predicted; this, by comparison with the observed output, serves to support some variants of the basic model, while invalidating others.In dorsal root ganglia from 15‐day chicken embryos, the assumption of a metabolic steady state was supported by a constant output of labelled CO2 from [l‐14C]glucose for 15 or more hours, except for the initial period of isotopic equilibration. By use of the new equations, it is concluded that in these ganglia (a) recycling in the pentose cycle can be 100% efficient in some incubation conditions, but not in others, (b) more CO2 is released from the pentose cycle than from the citric acid cycle, (c) large, quantifiable differences exist between the utilization of the various carbon atoms of glucose, and (d) a pool of intermediates within the pentose cycle, with a time constant of about 1 h, explains a large delay observed in the output of C‐6 of glucose into CO2, which occurs with a time constant as long as 5 h under some conditions. Under conditions where recycling is complete in the pentose cycle, this cycle must operate in isolation from glycolysis, which would otherwise convert much of the output of the pentose cycle to lactate. This may explain the role of fructose‐1,6‐diphospha‐tase in the tissue, without recourse to the oft‐proposed, puzzling, and ATP‐degrading‘futile cycle’between fructose‐6‐P and fructose‐1,6‐diP.It is proposed that the new equations may be suitable for similar analyses on some, but not all, other tissues.