bluuebunny/crossref_metadata_2025 huggingface dataset:
KINETIC ANALYSIS OF PHENYLALANINE‐INDUCED INHIBITION IN THE SATURABLE INFLUX OF TYROSINE, TRYPTOPHAN, LEUCINE AND HISTIDINE INTO BRAIN CORTEX SLICES FROM ADULT AND 7‐DAY‐OLD RATS
Authors: Vahvelainen M.‐L. , Oja S. S.
Published: October 2006

—An attempt was made to isolate the saturable uptake from the unidirectional influx of amino acids into tissue slices and to estimate the transport constants and maximal velocities of saturable transport. The method was applied to studies on the inhibition of phenylalanine in the saturable influx of tyrosine, tryptophan, histidine and leucine into brain cortex slices from adult and 7‐day‐old rats. In both age groups phenylalanine inhibited the influx of the other amino acids, and vice versa. The apparent transport constants of the other amino acids increased in the presence of phenylalanine more noticeably in the slices from 7‐day‐old rats than in those from adult rats, whereas the concomitant influx of phenylalanine was inhibited less in the slices from 7‐day‐old rats. In immature animals in vivo competition between amino acids may play a more marked role in the supply of amino acids from plasma to brain, as the transport systems in brain slices from 7‐day‐old rats become saturated with extracellular amino acids more readily than do the transport systems in brain slices from adult rats.
LOWERED MONOAMINE OXIDASE ACTIVITY IN BRAINS FROM ALCOHOLIC SUICIDES
Authors: Gotttries C. G. , Oreland L. , Wiberg Å. , Winblad B.
Published: October 2006

—Monoamine oxidase (MAO) activity in the brains of 15 suicides, of whom 8 were alcoholics, was compared to a control material of 20 individuals without known mental disorder. At autopsy 13 different parts of the brain were macroscopicaily dissected out and the MAO activity in the samples estimated with β‐phenylethylamine and tryptamine as substrates.

The MAO activity in all parts of the brain investigated was found to be significantly lower in the alcoholic suicides as compared to the controls, while there was no significant difference between the non‐alcoholic suicides and controls. Different variables which might have influenced the MAO activity were investigated. There was no significant correlation between age and tryptamine‐oxidizing activity, but a positive correlation between age and β‐phenylethylamine‐oxidizing activity was found. There was also a significant difference between the series in the time lapse between death and autopsy and in the time during which the dead body was kept at room temperature. However, neither of these variables could explain the differences between the series. The results thus demonstrate a connection between low MAO activity in the brain and suicidal behaviour among alcoholics.
CHANGES IN THE LEVELS OF DNA, RNA, PROTEIN AND DNases IN DEVELOPING AND OLD CHICK BRAIN
Authors: Shrivastaw K. P. , Rao K. Subba
Published: October 2006

—The levels of DNA, RNA, protein and activities of acid and alkaline DNases in developing and old chicken brain were studied. A rapid increase in DNA content was found in the embryonic brain until just prior to hatching. Thereafter, with a transient plateau around the day of hatching, the DNA continued to increase but at a very slow rate. Two‐year‐old brain was found to have a markedly higher level of DNA as compared to the 10th day postnatal value. RNA showed a steady increase up to the 20th day of embryonic life. Protein levels showed a gradual increase throughout the period studied. Both acid and alkaline DNases exhibited maximum activity during embryonic life, i.e. at a time when rapid cellular proliferation was occurring. With advancing age, the acid DNase activity showed a marked decline thus exhibiting no correlation to the high level of DNA found in the old brain. The alkaline DNase activity, however, was still at a significant level in the 2‐year‐old brain.
THIAMINE PHOSPHATE METABOLISM AND POSSIBLE COENZYME‐INDEPENDENT FUNCTIONS OF THIAMINE IN BRAIN1
Authors: Berman K. , Fishman R. A.
Published: October 2006

Abstract—

The effect of depolarization of rat brain cortex slices on the relative distribution of thiamine among its various phosphate esters and on the efflux of thiamine was studied as a probe of possible coenzyme‐independent neurophysiological functions of thiamine. Electrical pulses for 30 min increased lactate production but did not affect the levels of thiamine esters. Depolarization with 41 mM‐potassium decreased thiamine diphosphate by only 3 percent (P= 0.05). Thiamine triphosphate levels (TTP) were unaffected by depolarization but doubled during incubation for 1 h in which time efflux of 40 percent of the total thiamine from the slices as unesterified thiamine occurred. Depolarization by potassium released a small but highly variable portion of the thiamine content of superfused cortex slices above the basal rate of efflux. The basal efflux was partially sodium dependent. Thiamine efflux was unaffected by acetylcholine, ouabain, or tetrodotoxin, compounds previously reported to increase thiamine efflux. The incorporation of 32P1 into the endogenous thiamine phosphates of cortex slices was studied. Incorporation into thiamine diphosphate reached only 20 percent of the specific activity of its precursor, ATP, after 2h of incubation while the incorporation into TTP approached equilibrium with ATP in 15‐30 min indicating that the TTP pool was the most rapidly turning over of the thiamine phosphates. The data suggest that only a small portion of the TDP pool undergoes rapid turnover and serves as a precursor for TTP. The rapid turnover of TTP phosphoryl groups is consistent with specific functions for this compound related to its potential for phosphorylation reactions. An analog of TTP with the β, γ oxygen bridge replaced by a methylene group decreased TDP levels and increased thiamine when incubated with cortex slices, but did not effect thiamine monophosphate or triphosphate levels indicating inhibition of thiamine pyrophosphokinase.
MODIFICATIONS IN SOLUBLE PROTEIN KINASE AND CYCLIC‐AMP BINDING CAPACITY OF DEVELOPING RAT BRAIN
Authors: Takahashi T. , Matsuzaki S. , Nunez J.
Published: October 2006

Abstract—

Histone and casein phosphoprotein‐kinase activities were determined in rat brain soluble fraction at various stages of development.

Cyclic AMP‐independent or basal histone kinase activity increased, whereas cyclic AMP‐dependent activity decreased in whole soluble fraction with the age. On the contrary, whole soluble cyclic AMP‐dependent and ‐independent casein kinases activities did not show any difference during development.

The percentage of activation by cyclic AMP of histone kinase activity and [3H] cyclic‐AMP binding activity in the soluble fraction decreased markedly during development.

By DEAE‐cellulose chromatography the histone kinase was separated mainly into 4 peaks; the fourth peak was strongly stimulated by cyclic AMP. Stimulation by cyclic AMP was higher in the 4‐day‐old rat brains than in the 9‐ and 30‐day‐old. In the 9‐day‐old rats the ratio of cyclic AMP‐dependent histone kinase in respect to the cyclic AMP‐independent enzyme was higher than in 4‐ and 30‐day‐old rats.

Casein kinase activities in the brains of 9‐ and 30‐day‐old rats were separated by DEAE‐cellulose chromatography into three peaks of which the third one was stimulated by cyclic AMP. Little, if any, difference was observed for casein kinase during the development. These results suggest that brain histone and casein kinase are different enzymes:
SUBCELLULAR DISTRIBUTION AND ACTIVATION BY NON‐IONIC DETERGENTS OF GUANYLATE CYCLASE IN CEREBRAL CORTEX OF RAT
Authors: Deguchi T. , Amano E. , Nakane M.
Published: October 2006

Abstract—

Non‐ionic detergents stimulated particulate guanylate cyclase activity in cerebral cortex of rat 8‐ to 12‐fold while stimulation of soluble enzyme was 1.3‐ to 2.5‐fold. Among various detergents, Lubrol PX was the most effective one. The subcellular distribution of guanylate cyclase activity was examined with or without 0.5% Lubrol PX. Without Lubrol PX two‐thirds of the enzyme activity was detected in the soluble fraction. In the presence of Lubrol PX, however, two‐thirds of guanylate cyclase activity was recovered in the crude mitochondrial fraction. Further fractionation revealed that most of the particulate guanylate cyclase activity was associated with synaptosomes. The sedimentation characteristic of the particulate guanylate cyclase activity was very close to those of choline acetyltransferase and acetylcholine esterase activities, two synaptosomal enzymes. When the crude mitochondrial fraction was subfractionated after osmotic shock, most of guanylate cyclase activity as assayed in the absence of Lubrol PX was released into the soluble fraction while the rest of the enzyme activity was tightly bound to synaptic membrane fractions. The total guanylate cyclase activity recovered in the synaptosomal soluble fraction was 6 to 7 times higher than that of the starting material. The specific enzyme activity reached more than 1000 pmol per min per mg protein, which was 35‐fold higher than that of the starting material. The membrane bound guanylate cyclase activity was markedly stimulated by Lubrol PX. Guanylate cyclase activity in the synaptosomal soluble fraction, in contrast, was suppressed by the addition of Lubrol PX. The observation that most of guanylate cyclase activity was detected in synaptosomes, some of which was tightly bound to the synaptic membrane fraction upon hypoosmotic treatment, is consistent with the concept that cyclic GMP is involved in neural transmission.
IMMUNOLOGICAL PROPERTIES OF RAT BRAIN CHOLINE ACETYLTRANSFERASE1
Authors: Rossier J.
Published: October 2006

Abstract— Four antisera active against choline acetyltransferase (ChAc) were obtained by injecting 22 rabbits with rat brain ChAc. The ChAc preparations used for immunization (specific activity from 015 to 2 μmol/min/mg of protein) were not pure and the antisera produced were not monospecific. The antisera inhibited and precipitated ChAc, but the precipitated enzyme‐antibody complexes still retain ChAc activity. One millilitre of the most active serum precipitates 0–5 μmol/min of rat brain ChAc at the equivalence point. Its titre expressed in mg/ml of immunoglobulins precipitated with the antigen and the equivalence point was calculated at about 0.08 mg/ml of serum. This relatively low titre explains the lack of any visible ChAc immunoprecipitate in an immunodiffusion test. Cross‐reactivity studies revealed that ChAc has undergone few changes during evolution, since antisera produced against rat brain ChAc still precipitate ChAc from fish (Torpedo).
THE NUCLEAR DNA CONTENT OF LARGE VENTRAL SPINAL NEURONS
Authors: McIlwain D. L. , Capps‐Covey Patsy
Published: October 2006

Abstract— A nuclear fraction has been obtained from large spinal neurons previously isolated from bovine ventral spinal cord in bulk suspensions. The fraction contained an average of 5.3 ± 0.9 pg DNA/nucleus, indicating a high incidence of diploid nuclei. This conclusion was confirmed by distribution analysis of DNA in propidium iodide‐stained nuclei examined by flow microfluorometry. That technique showed that at least 90% of the nuclei from large spinal neurons are diploid. Mixed, mostly non‐neuronal nuclei derived from many types of cells in the ventral spinal cord contained an average of 5.9 ± 0.6 pg DNA/nucleus, 19% of which possibly possess more than diploid amounts of DNA. The uniform DNA content in nuclei of large spinal neurons and most other types of cells in the ventral spinal cord contrasts sharply with a wide variation (av 26‐fold) in the nuclear volumes of the same cells.
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.
ALTERATIONS IN BRAIN OCTOPAMINE AND BRAIN TYROSINE FOLLOWING PORTACAVAL ANASTOMOSIS IN RATS
Authors: James J. H. , Hodgman Jane M. , Funovics J. M. , Fischer J. E.
Published: October 2006

Abstract— Following portacaval anastomosis in the rat, plasma and brain tyrosine are markedly elevated, although brain tyrosine is increased to a significantly greater degree than plasma tyrosine. Both plasma and brain tyrosine as well as brain octopamine correlated well with a presumed index of impaired hepatic function, the ratio of liver weight to body weight in shunted rats. A significant positive correlation was observed between brain octopamine and brain tyrosine. The significance of these findings to the etiology and treatment of clinical hepatic encephalopathy is discussed.
THE SPECIFICITY AND SULFHYDRYL SENSITIVITY OF THE INOSITOL TRANSPORT SYSTEM OF THE CENTRAL NERVOUS SYSTEM
Authors: Spector R.
Published: October 2006

Abstract— The transport of two cyclohexitol stereoisomers, myo‐inositol (inositol) and scyllo‐inositol (scyllitol), from blood into the CNS in vivo and into the choroid plexus in vitro was studied. In vitro, the uptake of [3H]scyllitol or [3H]inositol by choroid plexuses, isolated from rabbits and incubated in artificial CSF, was measured. Both scyllitol and inositol inhibited [3H]scyllitol or [3H]inositol accumulation by the choroid plexus. Inositol competitively inhibited [3H]scyllitol accumulation and both isomers had a comparable affinity (Kt= 0.1 mm) for the single cyclohexitol accumulation system. The other 6 stereoisomers tested had an order of magnitude less affinity for the cyclohexitol accumulation system of choroid plexus. Thiol reagents that penetrate cells inhibited inositol accumulation by choroid plexus more effectively than nonpenetrating thiol reagents. In vivo, in unanesthetized rabbits. the transport of unmetabolized [3H]inositol from blood into CSF, choroid plexus and brain was readily saturated by increasing the plasma levels of myo‐inositol but not by the stereoisomer d‐chiroinositol. Similarly, the transport of unmetabolized [3H]scyllitol into CSF, brain and choroid plexus was readily saturated by increasing the plasma levels of myo‐inositol. Beside documenting the stereospecificity and thiol reagent sensitivity of the inositol transport mechanism of the choroid plexus, these results provide further evidence that the choroid plexus is a locus for cyclohexitol transport between blood and CSF. Moreover, they show that scyllitol, which, like inositol, is present at a higher concentration in brain than plasma, can be transported from blood into CSF and brain by the same system that transports inositol.
RATE OF ACCUMULATION OF ACETYLCHOLINE IN DISCRETE REGIONS OF THE RAT BRAIN AFTER DICHLORVOS TREATMENT
Authors: Stavinoha W. B. , Modak A. T. , Weintraub S. T.
Published: October 2006

Abstract– The time course for accumulation of acetylcholine was measured in rat brain regions after treatment with 15 mg/kg, i.v., dichlorvos. With this dose of dichlorvos 84‐96% of the brain cholinester‐ase is inhibited within 1 min. After killing and concomitant enzyme inactivation through microwave irradiation, the acetylcholine levels were measured by pyrolysis‐gas chromatography. In the brain regions studied, the striatum had the highest rate of accumulation of acetylcholine and the cerebellum had the lowest. The calculated turnover time in minutes for the regions of the brain were cerebral cortex 0.9; hippocampus 1; striatum 1.4; cerebellum 1.7; medulla‐pons 2.2; midbrain 4.5; thalamus 5.6.
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

—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

—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

Both 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.
ON THE SEQUENTIAL CLEAVAGE OF MYELIN BASIC PROTEIN BY CATHEPSINS A AND D
Authors: Marks N. , Grynbaum A. , Benuck M.
Published: October 2006

Abstract— A lysosomal carboxypeptidase (cathepsin A) known to increase in demyelination (experimental allergic encephalomyelitis and multiple sclerosis) and purified 277 fold from bovine brain failed to attack myelin basic protein. Prior treatment of basic protein with bovine cathepsin D (EC 3.4.23.5) at pH 3.2 led to the production of three polypeptides one of which, Phe43‐Phe88, acted as a substrate for the carboxypeptidase. Incubation of this fragment with cathepsin A at pH 5.5 led to the release of C‐terminal Phe equivalent to 50% of the total within 6h at 25°C and smaller amounts of the adjacent His (position 87) and Val (86). Purified cathepsin A was devoid of aminopeptidase and arylamidase contaminants when tested with a variety of di‐ and tripeptides and with the polypeptide fragment of myelin basic protein Phe89‐Arg169. These studies in vitro with two different lysosomal enzymes show that cathepsin D activity is rate‐limiting. A demonstration of step‐wise cleavage by lysosomal enzymes may be relevant to mechanisms regulating protein turnover and to processes involved in demyelination.
EFFECT OF GLUCOCORTICOIDS ON NERVE GROWTH FACTOR‐MEDIATED ENZYME INDUCTION IN ORGAN CULTURES OF RAT SYMPATHETIC GANGLIA: ENHANCED RESPONSE AND REDUCED TIME REQUIREMENT TO INITIATE ENZYME INDUCTION
Authors: Otten U. , Thoenen H.
Published: October 2006

Abstract— After previous studies had shown that nerve growth factor produces a very similar change in the enzyme pattern of adrenergic neurons as does an increased activity of the preganglionic cholinergic nerves, the present experiments revealed that the nerve growth factor‐mediated selective induction of TH and DBH is enhanced by glucocorticoids in a way similar to that mediated by acetylcholine via nicotinic receptors. Corticosterone (5 μM) produced not only an increase in the maximal response to NGF but shifted the concentration response curve of TH to NGF to the left. The potentiation effect was shown to be specific for glucocorticoids, since other steroid hormones like testosterone, β‐estradiol and progesterone had no effect. Moreover, the glucocorticoid effect could be antagonized by cortexolone, suggesting an effect via glucocorticoid receptors. In addition to the potentiation of the nerve growth factor‐mediated enzyme induction, glucocorticoids reduced the exposure time to NGF, necessary to initiate maximal TH induction, from 4 h to 10 min. The glucocorticoid potentiation of NGF‐mediated specific enzyme induction is discussed in relation to the site and mechanism of action of NGF.
DIVERSITY OF METABOLIC PATTERNS IN HUMAN BRAIN TUMORS—I. HIGH ENERGY PHOSPHATE COMPOUNDS AND BASIC COMPOSITION1
Authors: Lowry O. H. , Berger S. J. , Chi M. M.‐Y. , Carter J. G. , Blackshaw A. , Outlaw W.
Published: October 2006

Abstract— A total of 25 human brain tumors and 4 specimens of human brain were rapidly frozen at the time of operation and analyzed for ATP, ADP, AMP, UTP, total nucleoside triphosphates, P‐creatine, creatine, inorganic P, creatine kinase, lipid and glycogen. Analyses were made on submicrogram samples dissected from frozen dried sections in order to obtain material as free as possible from admixture with brain, necrotic tissue, blood, etc. A method was developed to estimate the original water content of the frozen dried samples. The brain specimens contained five times as much glycogen as small mammal brains, otherwise the values were similar. The tumors were in fair to excellent energy status. Within the areas chosen for assay, most of ATP and total adenylate were substantially higher than in brain in the case of 5 out of 15 gliomas, 3 of 5 meningiomas, and 1 of 4 schwannomas. UTP was almost invariably higher and other nucleotide triphosphates (besides ATP and UTP) lower than in brain. Glycogen was extremely variable, ranging among the gliomas from 0.05% to 6% of dry wt (4 times the level in the human brains). Creatine plus P‐creatine, compared to cerebral cortex levels, ranged from 15 to 85% in gliomas, was about 25% in meningiomas and the only medulloblastoma, and varied between 6 and 8% in the schwannomas. P‐Creatine varied more or less in keeping with the energy status. Creatine kinase was exceedingly variable. It was almost zero in the schwannomas, the medulloblastomas, 3 of 5 meningiomas, and 2 of 15 gliomas, whereas in some of the gliomas the activity approached that found in brain.
MULTIPLE BINDING SITES OF HUMAN BRAIN AND LIVER MONOAMINE OXIDASE: SUBSTRATE SPECIFICITIES, SELECTIVE INHIBITIONS, AND ATTEMPTS TO SEPARATE ENZYME FORMS
Authors: White Helen L. , Glassman Ann T.
Published: October 2006

Abstract— MAO of human brain and liver mitochondria was solubilized by a procedure that preserved the substrate and inhibitor selectivities of the original mitochondrial preparation. Techniques that are designed to separate proteins on the basis of molecular size or net surface charge did not yield a physical separation of enzymically active A and B forms, even in the presence of ionic detergents or with limited proteolysis. However, sulfhydryl inhibitors, inorganic salts, ionic detergents, heat treatment, and sonication all tended to cause selective inactivation of serotonin‐metabolizing activity in solubilized preparations. Experiments with selectively inhibited (membrane‐bound or solubilized) MAO supported the concept of at least two independent kinds of substrate binding site, only one of which metabolizes serotonin (A type) and another (B type) which has a very strong affinity for β‐phenethylamine. l‐Norepinephrine, tryptamine, dopamine, and tyramine could be classified as common substrates. The lowest Km values were found for tryptamine at A sites and for β‐phenethylamine at B sites. Results of this study suggest that the different MAO sites could be part of the same large molecular complex, which may normally be embedded in the outer mitochondrial membrane so that A sites are more dependent on their lipid environment within this membrane.
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.
CHARACTERIZATION OF A CHONDROITIN SULPHATE PROTEOGLYCAN FROM OVINE BRAIN
Authors: White C. J. Branford , Hudson Margaret
Published: October 2006

Abstract— A proteoglycan has been isolated from ovine brain tissue using a dissociative method of extraction. The preparation was then purified using ion‐exchange and gel chromatography, and an apparent molecular weight of 2 ± 106 was estimated. Chemical analysis together with β‐elimination studies strongly suggested that the macromolecule contains chondroitin sulphate chains covalently bound to a common protein core through a serine‐xylose linkage. Immunological studies showed that a common antigenic component exists between the respective protein moieties of the proteoglycan and a proteoglycan isolated from bovine nasal cartilage.
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.
EFFECT OF DENERVATION AND OF AXOPLASMIC TRANSPORT BLOCKAGE ON THE IN VITRO RELEASE OF MUSCLE ENDPLATE ACETYLCHOLINESTERASE
Authors: Inestrosa N. C. , Ramírez B. U. , Fernández H. L.
Published: October 2006

Abstract— Cat geniohyoid muscle samples containing endplate regions, when incubated in vitro at 37°C in phosphate buffer (pH 73, release acetylcholinesterase (AChE; EC 3.1.1.7) to the bathing medium. By treating the muscle samples with collagenase (EC 3.4.4.19), it was confirmed that most of the AChE released came from the endplates. Enzyme liberation was studied 10 days after either local injection of 10mM‐cokhicine into the hypoglossal nerve or following nerve transection. Results showed that the rate of release is increased by denervation, but is not affected by axoplasmic transport blockage. It is postulated that the cellular contact between nerve and muscle—altered by denervation but not by interruption of axoplasmic transport—is an essential factor in maintaining the localization of end‐plate AChE within the synaptic cleft substance. This does not invalidate the possible participation of ACh and muscle activity in such enzyme localization.
TETRAHYDRO‐β‐CARBOLINES: SPECIFIC INHIBITORS OF TYPE A MONOAMINE OXIDASE IN RAT BRAIN1
Authors: Meller E. , Friedman E. , Schweitzer J. W. , Friedhoff A. J.
Published: October 2006

Abstract— A series of serotonin and phenethylamine analogs were tested for their ability to differentially inhibit type A or B monoamine oxidase (EC 1.4.3.4) in rat hypothalamus. The most specific and potent effects were shown by several tetrahydro‐β‐carbolines which competitively inhibited the oxidative deamination of serotonin at micromolar concentrations. In contrast, effective inhibition of phenethylamine deamination was observed only at or near millimolar concentrations of these drugs. Significant reductions of type A but not type B MA0 activity were also observed after administration of 25–100 mg/kg, i.p., of tetrahydro‐β‐carboline and its 6‐methoxy derivative.
ON THE UPTAKE OF INOSITOL BY RAT BRAIN SYNAPTOSOMES
Authors: Warfield Anna , Hwang Shing Mei , Segal Stanton
Published: October 2006

The 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

The 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.
FAST AXOPLASMIC TRANSPORT OF A CALCIUM‐BINDING PROTEIN IN MAMMALIAN NERVE
Authors: Iqbal Zafar , Ochs Sidney
Published: October 2006

Abstract— Calcium is transported at a fast rate of 410 mm/day in cat sciatic nerve on injection of 45Ca2+ into the L7 dorsal root ganglia. Nerve segments corresponding to the crest and the plateau regions of transported activity were analyzed by column chromatography on Sephadex G‐100 and Biogel A 5m columns and the fast transported 45Ca2+ found to be bound to a protein of 15,000 dalton. Using [3H]leucine as a precursor, a labeled calcium binding protein (CaBP) was found located at the same position in elution volumes from the columns as was the protein‐bound 45Ca2 +. The level of [3H]‐labeled CaBP in the crest and plateau regions were compared using column chromatography and polyacrylamide gel electrophoresis techniques and approx 3×4 times more [3H]‐labeled activity was found in the crest as compared to the plateau. These findings indicate that Ca2+ is fast transported in association with the CaBP. The relation of CaBP to the transport filament model of axoplasmic transport and its possible role in nerve are discussed.
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.