bluuebunny/crossref_metadata_2025 huggingface dataset:
GALACTOSYLSPHINGOSINE GALACTOSYL HYDROLASE IN RAT BRAIN: PROBABLE IDENTITY WITH GALACTOSYLCERAMIDE GALACTOSYL HYDROLASE1
Authors: Miyatake T. , Suzuki K.
Published: October 2006

Abstract— Activities of rat brain galactosylsphingosine (psychosine) and galactosylceramide (galactocerebroside) galactosyl hydrolases were compared using several criteria. Aqueous homogenates of rat brain were extracted at ‐30°C with a mixture of ether‐methanol (3:1, v/v). This procedure eliminated most of endogenous galactosylceramide and improved the linearity of the enzymatic reaction without inactivating the enzyme. The thermostability of both enzymes was identical while the reference 4‐methylumbelliferyl β‐galactosidase was less thermostable. The enzymes, solubilized from the ether‐methanol powder, were quantitatively precipitated in the combined ammonium sulphate fractions of 20–30% and 30–40% saturation. DEAE‐cellulose column chromatography gave identical elution patterns for the two enzymes, with a single major and two minor peaks. Electrofocusing of the major activity peak, obtained from the DEAE‐cellulose column, produced a sharp single peak of galactosylsphingosine‐ and galactosylceramidehydrolysing activities at an isoelectric point of pH 4.45. Developmental changes of these enzymes were identical, showing the most rapid rise concomitant with the period of active myelination. During development, at different purification steps, and in different organs, the ratio of the activities of galactosylsphingosine and galactosylceramide galactosyl hydrolases was relatively constant. While none of these criteria provides definitive proof of identity, they collectively suggest strongly that a single enzyme might catalyse hydrolysis of both galactosylsphingosine and galactosylceramide.
PURIFICATION OF SOLUBLE GLYCOPROTEINS FROM HUMAN NERVOUS TISSUE AND LIVER
Authors: Haglid K. G. , Rounnbauck L. , Stavrou D.
Published: October 2006

—The isolation of some water‐soluble, 50% methanol‐soluble glycoproteins from human normal brain, human ependymoma and human liver is reported. One of them (AM protein) has a similar, or even identical, electrophoretic mobility to brain‐specific protein S‐100 under certain electrophoretic conditions. Although bands of identical mobility are found in both brain and liver samples, we lack experimental evidence, at the present stage of this work, to draw conclusions on the identity (or relatedness) of such proteins. On the other hand, the brain‐soluble glycoproteins appear to be antigenically different from brain protein S‐100, from brain α2‐glycoprotein and from GP 350 glycoprotein.
PHOSPHOLIPID METABOLISM IN CULTURED NEUROBLASTOMA AND GLIOMA CELLS INCUBATED WITH CARBAMYLCHOLINE AND NOREPINEPHRINE
Authors: Eichberg J. , Shein H. M. , Hauser G.
Published: October 2006

Abstract—

Cultures of cloned neuroblastoma cells (N1E) in stationary phase and cloned glioma cells (C21) in confluency showed substantial differences in phospholipid composition. As a percentage of lipid P, N1E contained more phosphatidylcholine, less ethanolamine phosphoglycerides and much less sphingomyelin than C21. When incubated with 32Pi both cell lines incorporated comparable amounts of radioactivity into total phospholipids. In NIE, phosphatidylcholine contained much more and phosphatidylinositol and phosphatidic acid somewhat less label as compared to C21. The presence in the incubation medium of either norepinephrine or carbamylcholine failed to elicit stimulation of 32P incorporation into any phospholipid class.
EFFECT OF COLCHICINE ON THE DELAYED APPEARANCE OF LABELLED PROTEIN INTO SYNAPTOSOMAL SOLUBLE PROTEINS1
Authors: Crothers S. D. , McCluer R. H.
Published: October 2006

Abstract—

The effect of colchicine administration on the accumulation of radiolabelled soluble protein of brain synaptosomes was studied. Following injection of radiolabelled leucine, colchicine (injected bitemporally) was shown to block this delayed accumulation in limited brain areas. This effect supports the conclusion that the delayed appearance of label is a reflection of axoplasmic transport and demonstrates that colchicine can be utilized to block such transport in limited brain areas.
UPTAKE OF 3‐O‐METHYL‐d‐GLUCOSE INTO CULTURED HUMAN GLIOMA CELLS
Authors: Edström A. , Kanje M. , Walum E.
Published: October 2006

Abstract—

Human glioma cells (138 MG) were found to take up 3‐O‐methyl‐d‐glucose (3‐OMG) by a saturable low affinity transport system with a Km of 20 mm and a Vmax of 500 nmol/mg protein/min. About 20 per cent of the total uptake was due to passive diffusion. d‐Glucose was a competitive inhibitor with a Ki of 10 mm. Follow‐up experiments indicated that the same transport mechanism is involved in the uptake of n‐glucose and 3‐OMG. Phloretin (0·02 mm) and cytochalasin B (0·002 mm) strongly inhibited the uptake of 3‐OMG, whereas phlorizin (0·02 mm), ouabain (0·1 mm), NaCN (0·5 mm) and iodoacetic acid (1·0 mm) had no effect. The data suggest that 3‐OMG and d‐glucose enter 138 MG cells mainly by a Na+‐independent passive carrier‐mediated transport system. Serum‐deprivation doubled the population doubling time (Td) without affecting the total uptake of 3‐OMG. An increase in the non‐specific (diffusional) uptake was balanced by a decrease in the specific (carrier‐medíated) uptake. After addition of dibutyryl cyclic AMP (dbcAMP, 0·25 mm) the cells attained a morphology characteristic of differentiated glia cells. Td was maintained unchanged. The non‐specific uptake of 3‐OMG was not affected in cells grown in serum‐containing medium plus dbcAMP, whereas the specific uptake increased by 40 per cent and there‐fore also the total uptake. Similar, but more pronounced, changes were observed if serum‐deprived cells were treated with dbcAMP.
ALTERATIONS IN ACETYLCHOLINESTERASE ISOENZYME PATTERN OF HIPPOCAMPUS AFTER SEPTAL LESIONS IN RAT BRAIN
Authors: Oderfeld‐Nowak Barbara , Skangiel‐Kramska Jolanta
Published: October 2006

Abstract—

The effect of septal lesions upon the AChE (EC 3.1.1.7) isoenzymic pattern in the hippocampus of the rat brain was studied 1–3 months after surgery by means of polyacrylamide disc electrophoresis.

Alterations in the isoenzymic pattern were found in the membrane‐bound but not in the soluble fraction of the enzyme. In addition to the two slowly migrating bands seen in the membrane‐bound AChE fraction of the normal hippocampus, the fast‐migrating isoenzyme becomes visible.
EVIDENCE FOR THE ROLE OF BRAIN BIOGENIC AMINES IN DEPRESSED MOTOR ACTIVITY SEEN IN CHEMICALLY THYROIDECTOMIZED RATS1
Authors: Rastogi R. B. , Lapierre Y. , Singhal R. L.
Published: October 2006

Abstract— The effects of exposure to an antithyroid drug, methimazole, on brain tyrosine hydroxylase and tryptophan hydroxylase activity, as well as the levels of norepinephrine, dopamine, 5‐hydroxytryptamine and 5‐hydroxyindoleacetic acid have been investigated in maturing brain. Daily treatment of neonatal rats with methimazole for 30 days induced chemical thyroidectomy as evidenced by significant impairment of body and brain growth. The activities or brain tyrosine hydroxylase and tryptophan hydroxylase and the levels of norepinephrine, dopamine and 5‐hydroxytryptamine were markedly altered in a dose‐ and time‐dependent manner in methimazole‐treated rats. Conversely, the concentration of brain 5‐hydroxyindoleacetic acid was elevated (46%) by methimazole administration. Treatment with the antithyroid drug failed to exert any significant effect on the endogenous levels of brain tryptophan, as well as on the activity of the deaminating enzyme, monoamine oxidase. Administration of triiodothyronine (25 or 100 μg/100 g) to hypothyroid rats for 30 days did not produce any appreciable effect upon the neurochemical parameters related to either norepinephrine or 5‐hydroxytryptamine mctabolism. However, increasing the dose of triiodothyronine to 250 μg/100 g significantly elevated the levels of norepinephrine and 5‐hydroxytryplamine as well as the activities of the two synthesizing enzymes, tyrosine hydroxylase and tryptophan hydroxylase. Brain 5‐hydroxyindoleacetic acid levels were restored to normal values in thyroid hormone‐deficient rats treated with this higher dose of triiodothyronine. Evidencc also was obtained to show that chemical thyroidectomy suppressed the spontancous locomotor activity in neonatal rats; the changes being apparent at 15 days of age. Our data support the view that thyroid hormone in neonatal life displays an important regulatory effect on the metabolism of norepinephrine, dopamine and 5‐hydroxytryptamine. Since certain amines have been known to be implicated as the neurochemical substrates for behavioural arousal, it is conceivable that the observed hypoactivity in methimazolc‐treated rats may, at least in part, be related to impaired maturation of norepinephrine and dopamine‐synthesizing systems in brains of cretinous rats.
BIOPHYSICAL PROPERTIES OF RAT BRAIN CHOLINE ACETYLTRANSFERASE1
Authors: Rossier J.
Published: October 2006

Abstract— The molecular weight of choline acetyltransferase (ChAc) was determined by using a variety of methods. A molecular weight of 68,000 daltons was found. ChAc is a globular protein with an apparent radius of 3.39 nm (value of the Stokes radius). The existence of a dimeric form and higher aggregates is discussed
CALCIUM‐DEPENDENT RELEASE OF EXOGENOUSLY LOADED γ‐AMINO‐[U‐14C]BUTYRATE FROM SYNAPTOSOMES: TIME COURSE OF STIMULATION BY POTASSIUM, VERATRIDINE, AND THE CALCIUM IONOPHORE, A23187
Authors: Redburn Dianna A. , Shelton D. , Cotman C. W.
Published: October 2006

—Synaptosomes which had taken up [14C]GABA were applied to a filter and rapidly perfused with various solutions in order to study the time course of release of this putative transmitter and the characteristics of its release. Depolarization of the synaptosomes with veratridine or 56mM‐K+ or pretreatment with the Ca2+ ionophore, A23187, increased the calcium‐dependent efflux of [14C]GABA. Release of [14C]GABA was increased by Ca2+ within 0.3 s of exposure, and the maximal release rate was not maintained for longer than 0.6 s. The reduction in the rate of release was not attributable to a decrease in calcium influx, but rather appeared to reflect fatigue at some subsequent stage in release. Stimulation by 56mM‐K+ also elicited a calcium‐independent increase in the efflux of radioactive GABA, which appeared to arise in part from subcellular particles other than synaptosomes.
SUBCELLULAR FRACTIONS OF NORMAL HUMAN SUBSTANTIA NIGRA AND CAUDATE NUCLEUS; A STUDY OF THEIR MORPHOLOGY AND SOME ENZYMES INCLUDING GLUTAMATE DECARBOXYLASE AND CHOLINE ACETYLTRANSFERASE
Authors: Hickey Susan M. , Ansell G. B. , Mitchell K. , Pearce G. W.
Published: October 2006

Abstract— Subcellular fractions have been prepared from normal human caudate nucleus and substantia nigra by a standard fractionation technique and the fractions assayed for the following enzymes, which were studied because of their relevance to neurotransmission and pathological change: glutamate decarboxylase (EC 4.1.1.15), choline acetyltransferase (EC 2.3.1.6), acetylcholinesterase (EC 3.1.1.7), acid phosphatase (EC 3.1.3.2) and succinate dehydrogenase (EC 1.3.99.1). The distribution of these enzymes was assessed in relation to the morphology of the fractions as observed by electron microscopy. As with preparations from animal cerebral cortex, acetylcholinesterase and acid phosphatase were found mainly in fractions known to contain plasma membranes, synaptosomal membranes and microsomes. The levels of choline acetyltransferase in fractions from the substantia nigra were too low to measure but, in the caudate nucleus, the enzyme was concentrated in the crude mitochondrial fraction (P2), especially in the P2B and P2C subfractions. A high proportion of the glutamate decarboxylase activity was present in the P2 fractions of the substantia nigra and caudate nucleus and, although the synaptosomal (P2B) fraction contained the enzyme, significant amounts were found in the mitochondrial (P2C) fraction. This may have been due to some contamination of the mitochondria with small synaptosomes. Succinate dehydrogenase showed a conventional bimodal distribution between synaptosomes and mitochondria with a concentration in the latter.
ISOLATION OF HYDROPHOBIC PROTEINS BINDING AMINO ACIDS. STEREOSELECTIVITY OF THE BINDING OF L‐[14C]GLUTAMIC ACID IN CEREBRAL CORTEX
Authors: Robertis E. De , DE Plazas Sara Fiszer
Published: October 2006

From the total lipid extract of ncrve‐ending membranes or the homogenate of cerebral cortex a hydrophobic protein fraction binding L‐[14C]glutamic acid was separated by chromatography on Sephadex LH20. This protein could only be partially separated from the [14C]GABA‐binding protein and from the lipids that are present in the fraction; however, it was demonstrated that both amino acids bind to different sites. The saturation of the binding showed a high (Kd1= 0.3μM), a medium (Kd, = 5 μM) and a low (Kd, = 55 μM) affinity binding site. The high affinity binding site had a binding capacity of 0.53 nmol/mg of protein and was highly stereoselective for the L‐enantiomer. The binding of L‐[14C]glutamic acid was not inhibited by GABA, was slightly inhibited by glycine and glutamine and was strongly inhibited in a progressive order by DL‐a‐methylglutamic acid, L‐nuciferine, L‐aspartic acid and L‐glutamic acid diethyl ester. These results are compared with those previously obtained with the L‐glutamic acid‐binding protein isolated from crustacean muscle. The stereoselectivity of the binding and the possible role of this protein in synaptic transmission are discussed.
PROPERTIES OF l‐GLUTAMATE DECARBOXYLASE FROM BRAINS OF ADULT AND NEWBORN MICE1
Authors: Wu Jang‐Yen , Wong Esther , Saito Kihachi , Salto Kihachi , Roberts Eugene , Schousboe Arne
Published: October 2006

Abstract— l‐Glutamate 1‐carboxy‐lyase (EC 4.1.1.15) (GAD) and 4‐aminobutyrate‐2‐oxo‐glutarate aminotransferase (EC 2.6.1.19) (GABA‐T) have been purified from mouse brain (Wuet al. 1973; Schousboeet al., 1973) and their properties have been extensively studied (Wu & Roberts, 1974; Schousboeet al., 1974). The above enzymes were prepared from a water lysate of crude mitochondrial fraction, which accounted for only 25–30% of total GAD or GABA‐T activities in brain. A procedure has been developed which liberates approx 85% of total GAD and GABA‐T activities into supernatant. Two distinct, well‐separated peaks with GAD activity and a single peak with GABA‐T activity were observed when a concentrated extract from brain of adult or newborn mice was chromatographed on Sephadex G‐200 or Bio‐Gel A–1.5 m. The first peak appeared in the void volume and is. therefore. an entity of high molecular weight. The second peak gave elution characteristics which were identical to those of the enzyme that had been purified previously (mol wt = 85,000). These two GAD peaks were also clearly separated on polyacrylamide gel electrophoresis. The GAD activities in the two peaks showed similar pH profiles (optimum, 6.5). Km values (1–2 mM), immunodiffusion patterns and inhibitions by anti‐GAD IgG prepared against GAD purified from synaptosome‐containing crude mitochondrial fraction (60–80%). The physiological implications of high molecular weight and low molecular weight forms of GAD are discussed.
IDENTIFICATION OF D‐ASPARTIC ACID IN THE BRAIN OF OCTOPUS VULGARIS LAM
Authors: D'Aniello A. , Giuditta A.
Published: October 2006

Abstract— An assay method based on the use of specific oxidases has been used to search for D‐amino acids in the organs of Octopus vulgaris. A high concentration of D‐aspartate has been detected in the central brain and in the optic lobes but not in non‐nervous organs.

Other D‐amino acids appear to be absent from brain and from other tissues.
PHOSPHOINOSITIDE KINASES IN CHICK BRAIN AND SCIATIC NERVE, A DEVELOPMENTAL STUDY
Authors: SHAIKH NISAR A. , PALMER F. B. ST. C.
Published: October 2006

Abstract—

Phosphatidylinositol kinase and diphosphoinositide kinase activities were measured in homogenates of brain and sciatic nerve of developing chick embryos and chicks. Characteristics of the chick nervous system enzymes were similar to those reported for rat brain. Diphosphoinositide kinase was inhibited by high concentrations of ATP and by low concentrations of triphosphoinositide. Both activities were greatly enhanced by the non‐ionic detergent, Cutscum, and the ratio of detergent to protein in the reaction mixture was important. Optimum phosphatidylinositol kinase activity required a ratio of 7 : 1 for both tissues. The optimum ratio for diphosphoinositide kinase was 3:1 for nerve homogenates and 0.6:1 for brain. Cutscum increased the concentration of diphosphoinositide that is required for maximum diphosphoinositide kinase activity.

Developmental changes were the same for both kinase activities, which were low in unmyelinated brain and sciatic nerve. The activities correlated with the concentration of polyphosphoinositides in chick brain where they increased 4‐5 fold during the period of active myelination and remained high in the mature brain. The kinase activities correlated with the rate of triphosphoinositide deposition in sciatic nerve. Following a 2‐3 fold increase during the initial phase of myelination the activities declined to values as low as those of embryonic nerve.
ASSAY AND PROPERTIES OF 4‐AMINOBUTYRIC‐2‐OXOGLUTARIC ACID TRANSAMINASE AND SUCCINIC SEMIALDEHYDE DEHYDROGENASE IN RAT BRAIN TISSUE
Authors: Boer Th. De , Bruinvels J.
Published: October 2006

Abstract— The activity of 4‐aminobutyric‐2‐oxoglutaric acid transaminase (GABA transaminase) and succinic semialdehyde dehydrogenase was determined in total rat brain homogenate. GABA transaminase activity was measured using a coupled enzyme method which utilizes endogenous succinic semialdehyde dehydrogenase to convert the formed succinic semialdehyde into succinate. The concurrently produced NADH was used as an estimate of GABA transaminase activity. This method could be used since it was shown that the dehydrogenase was about twice as active as the transaminase and because no significant accumulation of the intermediate succinic semialdehyde could be detected. GABA transaminase was inhibited by high ionic strength. In contrast NaCl decreased the apparent Km and increased Vmax for succinic semialdehyde dehydrogenase at high but not al low tissue concentrations. Increasing tissue concentration also resulted in a decrease of the apparent Km, but did not change the Vmax of succinic semialdehyde dehydrogenase and it is suggested that this enzyme can exist in two distinct states of aggregation, one with a high and one with a low affinity for succinic semialdehyde. The high affinity form of the enzyme is thought to prevent succinic semialdehyde from accumulation in the GABA transaminase assay. It is concluded that within certain limits the coupled enzyme method described here can be used for the assay of GABA transaminase activity.
THE EFFECTS OF PENTOBARBITONE‐SODIUM ANAESTHESIA, SHOCK AVOIDANCE CONDITIONING AND ELECTRICAL SHOCK ON ACETYLCHOLINESTERASE ACTIVITY AND PROTEIN CONTENT IN REGIONS OF THE RAT BRAIN
Authors: Evans Christine A. , Kerkut G. A.
Published: October 2006

Abstract— Pentobarbitone sodium anaesthesia was found to produce an increase in protein content in some regions of the rat brain, i.e. posterior cortex, caudate nucleus, and a decrease in protein content in the ventral cortex.

Acetylcholinesterase expressed in terms of wet weight was found to increase in the cerebellum, medulla, and to decrease in the medial cortex, hippocampus, thalamus and caudate nucleus. The changes in activity were not explicable in terms of a direct effect of the anaesthetic on the enzyme. A decrease in protein content of rat brain was observed in the frontal cortex, ventral cortex, hippocampus and caudate nucleus after electrical shocks. Following shock avoidance conditioning procedure (shuttle‐box), decreases in protein content were observed in the medial cortex, posterior cortex, cerebellum and ventral cortex; in the thalamus an increase in protein content was observed.

Changes in AChE activity were observed following footshock in the frontal cortex and medulla where there was an increase in activity and in the caudate nucleus, hypothalamus, thalamus, and olfactory tubercle where there was a decrease in activity.

Following shock avoidance conditioning the activity of the AChE increased in posterior cortex, hippocampus, thalamus and hypothalamus and the activity of the enzyme decreased in the ventral cortex.
ON NEUROFILAMENT and NEUROTUBULE PROTEINS FROM HUMAN AUTOPSY TISSUE
Authors: Iqbal K. , Grundke‐Iqbal I. , Wisniewski H. M. , Terry R. D.
Published: October 2006

Abstract— Neurofilaments and neurotubules are the principal fibers of the mature normal neuron. In this study the protein subunits of these neurofibrils were isolated from human autopsy tissue, and compared by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, and by two dimensional peptide maps of the tryptic digest of these proteins labelled with 125I. The α and the β monomers of neurotubule are related but distinct in their peptide maps, while the major neurofilament protein subunit (molecular weight, 50,000) is remarkably similar to β tubulin. The neurofilament fraction binds colchicine, but the specificity is not yet determined. Neurotubule and neurofilament are also similar in having minor proteins which coelectrophorese on the gels. These results suggest that neurofilament and neurotubule may share one or more protein subunits.
GLYCOSPHINGOLIPIDS IN FETAL TAY‐SACHS DISEASE BRAIN AND LUNG CULTURES
Authors: Hoffman Linda M. , Amsterdam D. , Brooks S. E. , Schneck L.
Published: October 2006

Abstract— A study was undertaken of the glycosphingolipids in cell cultures derived from cerebellum of Tay‐Sachs disease fetal brain in order to determine the suitability of such cell strains as a model for Tay‐Sachs disease. The glycosphingolipids in the Tay‐Sachs disease cultured cerebellar cells were compared with those found in normal cultured cerebellar cells, normal and Tay‐Sachs cultured lung cells, and normal and Tay‐Sachs fetal brain. The glycolipids were separated by TLC, then analyzed by GLC of the trimethylsilyi derivatives of the methylglycosides of the sugar moieties. In the cultured cerebellar lines, the predominant gangliosides were GM2, GM3, and GD3. There was a 4‐fold increase of GM2 in the Tay‐Sachs as compared with the normal line. Only GM3 and GD3 gangliosides were found in the Tay‐Sachs and the normal fetal lung cell cultures. The major neutral glycosphingolipids in all of the cultured cells which were analyzed were glucosylceramide, lactosylceramide, digalactosyl‐glucosylceramide, and globoside. When the Tay‐Sachs cerebellar cells were labelled with [1‐14C]gluco‐samine, some radioactivity was observed in the trihexosylceramide band, indicating the presence of a small amount of a galactosamine‐containing trihexosylceramide which may be asialo‐GM2 (GA2). The trihexosylceramide in Tay‐Sachs fetal brain was identified as GA2 by GLC. Both Tay‐Sachs and normal fetal brain gangliosides were more complex than those found in the cultured cells. Long chain fatty acids (C24:0 and C24;1) predominated in all of the glycosphingolipids of the Tay‐Sachs and the normal cultured cerebellar cells. In contrast, the glycosphingolipids of Tay‐Sachs and normal fetal brain contained mainly the shorter chain fatty acids (C16:0, C18:0, and C18:1). The cerebrosides in both the Tay‐Sachs and normal fetal brains were mainly glucosylceramide with only small amounts of the galactosylceramide which predominates in infant brain. Cultured cells from the fetal Tay‐Sachs disease
FRACTIONATION OF GLYCOPROTEINS ASSOCIATED TO ADULT RAT BRAIN MYELIN FRACTIONS
Authors: Zanetta J.‐P. , Sarlieve L. L. , Mandel P. , Vincendon G. , Gombos G.
Published: October 2006

Abstract— The chloroform‐methanol insoluble residue of adult rat brain myelin fractions (My‐CMI) contains only 20% of protein but all myelin‐associated glycoproteins (Zanettaet al., 1977a). After solubilization in sodium dodecyl sulphate, these glycoproteins were separated by sequential affinity chromatography on 4 immobilized lectins. Ten fractions (9 of which contained only glycoproteins) were obtained. Glycoproteins added up to at least 25% of My‐CMI proteins. Many minor glycoproteins were detected in the different fractions. However most of them appeared not to be intrinsic to myelin. On the contrary a major glycoprotein electrophoretic band, component A, appeared to be intrinsic to myelin although its presence also on oligodendrocyte plasma membrane cannot be excluded. Component A was tentatively identified with the‘major myelin associated glycoprotein’described by QUARLES (1972, 1973a, b). It accounted for less than 0.4% of proteins and 8% of glycoproteins of myelin fractions and consisted of at least two‘glycopolypeptides’which, both, bind to concanavalin A and to the Ulex europeus lectin. The other major glycoprotein, component B, did not bind to any of the lectins used and, thus, must have N‐acetyl neuraminic acid as only terminal sugar. The separation of myelin‐associated glycoproteins according to their affinity for lectins allowed a tentative identification of the lectin binding sites of myelin sheath.
GUANYLATE CYCLASES IN CNS: ENZYMATIC CHARACTERISTICS OF SOLUBLE AND PARTICULATE ENZYMES FROM MOUSE CEREBELLUM AND RETINA
Authors: Troyer Edward W. , Hall Isabelle A. , Ferrendelli James A.
Published: October 2006

Guanylate cyclase activity is present in both soluble and particulate fractions of homogenates of mouse cerebellum and retina. Soluble guanylate cyclases in cerebellum and retina have an apparent Km for GTP of approx 40 and 70 μM, respectively; are stimulated by Ca2+ and Mg2+ in the presence of low Mn2+; and do not respond to NaN3, NH2OH or detergent. The particulate guanylate cyclase found in brain has an apparent Km GTP of 237 7mu;M, is not stimulated by Ca2+ or Mg2+ in the presence of low Mn2+, but is stimulated by NaN3, NH2OH, and detergent. In particulate fractions of normal retina, guanylate cyclase has two apparent Km GTP values (42 and 225 μM); has higher activity at low concentrations of Mn2+ (0.5 mM) than at high concentrations (5.0 mM); is inhibited by Ca2+; and does not respond to NaN3, NH2OH, or detergent. Retinas essentially devoid of photoreceptor cells (from mice with photoreceptor dystrophy) have soluble guanylate cyclase activity which is similar to that in normal retina, but have only 4% as much particulate guanylate cyclase activity. This residual particulate guanylate cyclase has an apparent Km GTP value of 392 μM and other properties similar to particulate guanylate cyclase from brain. These data indicate the presence of three distinguishable guanylate cyclases in CNS: (1) a soluble enzyme present in both brain and retina: (2) a particulate enzyme which is also present in brain and in the inner or neural retina: and (3) another particulate enzyme which is apparently unique and confined to retinal photoreceptor cells.
A COMPARISON OF GABA AND β‐ALANINE TRANSPORT AND GABA MEMBRANE BINDING IN THE RAT BRAIN1
Authors: Hitzemann R. J. , Loh H. H.
Published: October 2006

Abstract—

It was found that rat brain nerve endings contain a high affinity and Na‐ dependent transport system for [3H]β‐alanine ([3H]β‐ala). As determined from Michaelis‐Menten plots, the [3H]β‐ala Km was 2.8 × 10‐5 M and the Vmax was 0.29 nmol/mg protein/5 min. Under similar incubation conditions the [3H]GABA Km was 3.8 x 10‐6M and the Vmax was 6.3 nmol/mg protein/5 min. The [3H]β‐ala and [3H]GABA transport systems were further characterized by determining the IC50 values for a number of compounds. The compounds tested were GABA, β‐ala, l‐2,4‐diaminobutyric acid. DL‐3‐hyd‐roxy‐GABA, β‐guanidopropionic acid, strychnine, γ‐guanidobutyric acid, imidazole‐4‐acetic acid, DL‐proline, bicuculline, L‐serine, glycine, l‐α‐ala and taurine. DABA, dl‐3‐hydroxy‐GABA, β‐guanidopro‐pionic acid and γ‐guanidobutyric acid were more potent inhibitors of [3H]GABA than [3H]β‐ala transport. Strychnine, imidazole‐4‐acetic acid, proline and glycine were between 2 and 6 times more potent inhibitors of [3H]β‐ala than [3H]GABA transport. β‐Ala, bicuculline, serine, α‐alanine and taurine were all markedly more potent (12–150 times) inhibitors of [3H]β‐ala than [3H]GABA transport. IC50 values were also determined for the above compounds for the sodium‐dependent and the sodium‐independent binding of [3H]GABA to both fresh and frozen brain membranes. In general, the potency of these compounds to inhibit either sodium‐independent or sodium‐dependent binding was greater in fresh tissue. It was also observed that the neurophysiologically‘glycine‐like’amino acids were more potent inhibitors in the presence of NaCl. No significant correlations were found between [3H]GABA binding under any condition and [3H]GABA or [3H]β‐ala transport into nerve endings.
STIMULATION OF MUCLEAR RNA SYNTHESIS IN DENERVATED SKELETAL MUSCLES
Authors: Held Irene R.
Published: October 2006

Abstract— The endogenous activities of the RNA polymerases A and B are higher in nuclei isolated from slow‐twitch soleus and fast‐twitch extensor digitorum longus muscles which have been denervated for 2–3 days than in nuclei isolated from sham‐operated, contralateral muscles. This stimulation is not observed immediately after denervation and declines by the fifth day. The results suggest that some neural influence is exerted upon the contiguous muscle cell at the level of gene transcription.
CHANGES IN FATTY ACID COMPOSITION OF HUMAN BRAIN MYELIN LIPIDS DURING MATURATION1
Authors: Svennerholm L. , Vanier M.‐T. , Jungbjer B.
Published: October 2006

Abstract— The variation with age of the fatty acid composition of the major lipids in human brain myelin was compared with that of cerebral white matter from the same region. The myelin was isolated from the semiovale centre of the cerebrum of 27 subjects neonatal to old aged. The phospholipid, cholesterol and galactolipid concentrations were determined in all the samples, as were the proportions of the major phospholipid classes. The proportions of cholesterol and especially of the galactolipids increased in myelin during the first 6 months, and in cerebral white matter up to 2 years. During this period the individual phospholipids also varied substantially. Serine phosphoglycerides and especially sphingomyelins increased, and choline phosphoglycerides decreased.

The fatty acid patterns of ethanolamine phosphoglycerides (EPG) and sphingomyelins underwent the largest changes. The proportions of saturated fatty acids in EPG diminished rapidly, and there was an increase of monoenoic acids. Fatty acids of the linoleic acid series showed a peak between 4 and 12 months, after which time their proportion slowly diminished to old age. The major fatty acid of this series was docosatetraenoic acid, 22:4 (n‐6), which constituted more than 25% of total fatty acids at the maximum level. The fatty acid changes were larger in cerebral white matter, but from 2 years of age the EPG fatty acid pattern in myelin was similar to that in white matter. The fatty acid changes in serine and choline phosphoglycerides of myelin with maturation were much less striking than in EPG but of a similar type.

In myelin sphingomyelin the proportion of saturated long‐chain fatty acids, C16‐C22, diminished, while that of monoenoic acids increased and continued to do so up to old age. From 2 years of age the fatty acid patterns in myelin and cerebral white matter were quite similar. Also the fatty acid patterns of cerebrosides and sulphatides in cerebral white matter and myelin were the same except for the first 2 months of life. The same fatty acid changes occurred in cerebrosides and sulphatides as in the sphingomyelins, i.e. increased proportions of unsaturated (monoenoic) acids. The proportions of 24:1 and 24h:1 and of the odd‐numbered fatty acids 25:1 and 23h:1 continued to increase to old age.

The variations of the individual lipid fatty acid patterns were small except in the youngest age classes, in which the variations were presumably ascribable to the difficulty in determining the gestational age.
BIOCHEMICAL AND MORPHOLOGICAL EFFECTS OF TESTOSTERONE TREATMENT ON DEVELOPING SYMPATHETIC NEURONS
Authors: Dibner Mark D. , Black Ira B.
Published: October 2006

Abstract— Neonatal rats were treated with testosterone propionate (TP) or isoproterenol (ISO) to determine whether (1) increases in salivary gland mass are associated with alteration of developing sympathetic neurons and (2) whether effects on neuron growth are secondary to altered target mass itself or to increases in salivary growth factors. TP treatment is known to result in salivary tubule hypertrophy and elevated nerve growth factor (NGF) content whereas IS0 treatment results in acinar hypertrophy and no known alteration in NGF. TP treatment increased submaxillary gland weight as well as tyrosine hydroxylase (T‐OH) activity, adrenergic neuron numbers and total protein in the innervating superior cervical ganglion (SCG). Unilateral sialectomy prevented the increase in T‐OH activity in the SCG, suggesting that the salivary glands were necessary for this effect. T‐OH activity and total protein were elevated in the distant sixth lumbar sympathetic ganglion after TP treatment, suggesting that sympathetic development as a whole was affected and that humoral factors may be involved. Salivary gland weight was also elevated following ISO administration, but T‐OH activity in the SCG was not affected. These observations suggest that TP treatment increases T‐OH activity and sympathetic neuron numbers by alteration of specific salivary humoral growth factor(s).
IDENTITY OF MYELIN BASIC PROTEIN FROM MULTIPLE SCLEROSIS AND HUMAN CONTROL BRAINS: DISCOVERY OF A GENETIC VARIANT1
Authors: Chou C‐H. Jen , Chou Frank C.‐H. , Kowalski Thomas J. , Shapira Raymond , Kibler Robert F.
Published: October 2006

Abstract— Myelin basic protein was isolated from the brains of 7 multiple sclerosis and 5 control patients. When acid extracts of the delipidated brains were chromatographed on carboxymethylcellulose at alkaline pH the elution profiles were the same for the two groups of patients. Component I, the most basic species of the protein, from 2 multiple sclerosis and one control brains was fragmented by limited pepsin digestion. Tryptic peptide maps were prepared from the three major products, fragment 1–38, 39–89 plus 45–89 and 90–170. The amino acid compositions of corresponding peptides were identical except for a 50:50 substitution of serine for glycine in tryptic peptide 44–49 from one (N.L.) of the 2 patients with multiple sclerosis. Peptide 44–49. isolated from intact component 1 from the other 6 multiple sclerosis and 5 control brains, did not show this substitution. In both multiple sclerosis and control basic proteins phosphorus was present only in fragment 90–170 of component 3 in the amount of 0.22 mol of phosphorus/mol of protein. These data suggest that there is no difference in either the amino acid sequence or in the modification of basic protein from control and multiple sclerosis patients. The amino acid substitution in patient N.L. represents the first example of a mutation in basic protein.
CLEARANCE OF THE POLYAMINES FROM THE PERFUSED CEREBROVENTRICULAR SYSTEM OF THE RABBIT
Authors: Halliday C. A. , Shaw G. G.
Published: October 2006

Abstract— The clearance of the polyamines spermidine and spermine from cerebrospinal fluid was investigated in the rabbit by ventriculocisternal perfusion. Clearance involved both saturable and nonsaturable uptake processes. The saturable component was a high affinity system with an affinity constant of 21 μm for spermidine and 24 μm for spermine. The clearance of spermidine was reduced by the presence of spermine and vice‐versa. Other polyamine congeners also reduced spermidine and spermine clearance and it is suggested that the two polyamines share the same carrier. Evidence for concentrative uptake of polyamines into choroid plexus is presented and it is suggested that an active system may also transport polyamines into brain tissue. At high perfusion concentrations simple diffusion may also take place.
REGIONAL BIOSYNTHESIS OF ACETYLCHOLINE IN BRAIN FOLLOWING FORCED ORAL CHRONIC BARBITONE TREATMENT TO RAT
Authors: Nordberg Agneta , Wahlström G.
Published: October 2006

Abstract—

Rats received a solution of sodium barbitone as their only drinking fluid for 33 and 42–44 weeks. In three groups (A3, A12 and A30) the barbitone solution was withheld and replaced by water 3, 12 and 30 days respectively before death. Two other groups consisted of animals drinking barbitone until death (B) and untreated controls (C). Abstinence convulsions were recorded by jiggle cages.

Thirty nmol of tritium‐labelled choline ([3H]Ch) were injected i.v. and the rats were killed by decapitation 1 min later. A significantly higher content of tritium‐labelled acetylcholine ([3H]ACh) was found in the cerebellum + medulla oblongata + midbrain of rats receiving barbitone until death (group B) (+22%) and abstinent for 3 days (+54%) (group A3) compared with group C. The [3H]ACh content was also significantly increased in the hippocampus + cortex of rats abstinent for 3 days (+23%). In the striatum no significant effect on [3H]ACh content was found in any of the groups. The ratio [3H]ACh/[3H]Ch was significantly increased in the cerebellum + medulla oblongata + midbrain of rats in group B and A3 and in the hippocampus + cortex in group A3. These results might indicate an increased turnover of ACh.

The effect of long‐term barbitone treatment on the enzyme activities of brain choline acetyltransferase and acetylcholinesterase was also studied but no significant effect was found.
CELLULAR DISTRIBUTION OF 16S ACETYLCHOLINESTERASE
Authors: Fernandez Hugo L. , Duell Myron J. , Festoff Barry W.
Published: October 2006

Abstract—

Multiple molecular forms of acetylcholinesterase (AChE; EC 3.1.1.7), in crude extracts of various tissues from the rat, were distinguished by velocity sedimentation analysis on linear sucrose gradients. Skeletal muscle samples containing end‐plate regions showed three different forms of AChE with apparent sedimentation coefficients of 16, 10 and 4s. The 16s form was not detected in non‐innervated regions of skeletal muscle, large intestine smooth muscle, whole brain tissue, red blood cells or plasma. Spinal cord, a predominantly motor cranial nerve and mixed (sensory and motor) peripheral nerves contained 16, 10, 6.5 and 4S AChE. Ventral motor roots, supplying the sciatic nerve, contained these four forms of the enzyme, while corresponding dorsal sensory roots were devoid of the 16S form. The 16s‐AChE confined to ventral roots can be attributed totally to motor neurons and not to Schwann cells composing these roots. Whether the 16s‐AChE presently found in motor nerves has chemical identity with that found at motor end‐plates is the basis of future experiments.
5‐HYDROXYTRYPTOPHYL PEPTIDES: POTENT INHIBITORS OF A STORAGE COMPARTMENT OF SEROTONIN1
Authors: Tamir Hadassah , Wilchek Meir
Published: October 2006

Abstract—

Several analogues of 5‐hydroxytryptophan were tested for their ability to inhibit the binding of serotonin to serotonin‐binding protein (SBP), a protein found within serotonergic neurons which has a high affinity for serotonin. An N‐substituted dipeptide, N‐acetyl‐5‐hydroxytryptophan‐5‐hydroxytryptophan amide, was found to be an inhibitor of this binding. The inhibition (50% at 1.0 μM) was specific, since it did not affect other known sites of serotonin binding. The binding of serotonin to its membrane receptor was not affected by the dipeptide (up to 10 μM). Uptake of serotonin by synaptosomes was only slightly affected (9% at 10 μM), and aromatic‐L‐amino‐acid carboxy‐lyase(EC 4.1.1.28) and amine: oxygen oxidoreductase (deaminating) (flavin‐containing) (EC 1.4.3.4) were not inhibited (10 μM and 5 mM respectively), The peptide was not hydrolyzed by honiogenates of brain or myenteric plexus. The 14C‐labelled dipeptide was shown to be taken up by synaptosomes. However, the uptake of the peptide was not affected either by drugs that inhibit serotonin uptake or by serotonin itself although the uptake was abolished by excess 5‐hydroxytryptophan. Intraventricular injection of N‐acetyl dipeptide caused a biphasic effect depending on dose. Lower doses (10nmol) induced a decrease in serotonin brain levels (40%). Higher doses (300 nmol) caused a 95% increase in serotonin levels.

It is suggested that 5‐hydroxytryptophyl peptides may be used as potent specific inhibitors of SBP, a storage compartment of serotonin.
BRAIN TISSUE AND PLASMA ASSAY OF L‐DOPA AND α‐METHYLDOPA METABOLITES BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION
Authors: Freed Curt R. , Asmus Paul A.
Published: October 2006

Using reverse phase high‐performance liquid chromatography and electrochemical detection with mobile phases composed of simple acids, we have developed an assay technique to measure multiple catecholamines and their catechol metabolites in plasma or brain tissue with sensitivity to the picomole level. Ion‐pairing chromatography with nitric or trichloroacetic acid as the mobile phase permits separation and quantitation of norepinephrine, α‐methylnorepinephrine, epinephrine, dopamine, α‐methyldopamine, l‐DOPA, α‐methyldopa, carbidopa, and DOPAC. Alumina extraction selectively isolates catechols which are then separated on a reverse‐phase column and measured by a commercially available electrochemical detector. This method has been applied to measurement of L‐DOPA metabolites in patients with Parkinson's disease treated with L‐DOPA and carbidopa and to measurement of catecholamines in rat hypothalamus in the course of studies on L‐DOPA and α‐methyldopa metabolism. Dihydroxybenzylamine is added as an internal standard and standard curves are linear over two orders of magnitude in concentration with coefficients of variation averaging 3.1%. Quantitation is routinely done to 20 pmol with absolute sensitivity possible to 0.5 pmol.
AXONAL TRANSPORT OF LIPIDS IN THE RABBIT OPTIC SYSTEM
Authors: Haley James E. , Tirri Lawrence J. , Ledeen Robert W.
Published: October 2006

Abstract— Axonal transport of lipids was demonstrated in the rabbit optic system using [2‐3H]glycerol and [3‐14C]serine. Following intraocular injection of these precursors, radioactive lipids were detected in the optic tract, superior colliculus and lateral geniculate body over a 31 day period. The bulk of lipid appeared to migrate at a rate equivalent to that of rapidly transported protein which, when combined with a prolonged period of release into the axon, led to a peak of transported radioactivity at 6‐10 days for the 3 tissues. The suggestion of a second peak at 17 days indicated the possibility of a smaller slow component, although another interpretation is suggested. Analysis of individual transported lipids revealed [2‐3H]glycerol to label phosphoglycerides preferentially and [3‐14C]serine to be an effective precursor for sphingolipids and certain of the phosphoglycerides. [3‐14C]Serine labeled axonally transported proteins to an even greater extent than lipids, revealing the same fast and slow components previously shown with other amino acids.
EFFLUX OF PHENYLALANINE FROM RAT CEREBRAL CORTEX SLICES AS INFLUENCED BY EXTRA‐ AND INTRACELLULAR AMINO ACIDS
Authors: Korpi E. R. , Oja S. S.
Published: October 2006

Abstract— Effects of other amino acids on the efflux of l‐[3H]phenylalanine from rat cerebral cortex slices were studied in a superfusion system. Extracellular large neutral amino acids caused a strong trans‐stimulation of [3H]phenylalanine efflux. Some small neutral amino acids were less effective, whereas acidic and basic amino acids and the amino acids without an amino group in the α‐position were ineffective. Any trans‐inhibition was not detected. The stimulatory trans‐effects of phenylalanine and tryptophan were additive, reversible and concentration‐dependent. They were apparently mediated by the same mechanisms. The efflux of [3H]phenylalanine was much slower at 273 K than at 310 K, but the effects of unlabelled phenylalanine and tryptophan on it were qualitatively similar at both temperatures. Amino acids accumulated intracellularly at moderately high concentrations did not inhibit [3H]phenylalanine efflux, but phenylalanine, leucine, isoleucine and norleucine caused an enhancement. Spontaneous efflux of [3H]phenylalanine showed some similarities to physical diffusion, but its selective and specific modification by other amino acids strongly suggests the involvement of mediated processes.
ON THE MECHANISM OF OUABAIN INHIBITION OF SYNAPTOSOME PROTEIN SYNTHESIS
Authors: Verity M. Anthony , Brown W. Jann , Cheung Marshall K.
Published: October 2006

Abstract— Ouabain (200μm) inhibited incorporation of radiolabelled leucine or glycine into the protein of neonatal synaptosome fractions but had minimal effect on preparations from adult rats. Leucine uptake into synaptosomes was rapid but not influenced by 200μm‐ouabain in contrast to ouabain inhibition of [14C]glycine and [14C]γ‐aminobutyric acid uptake. Ouabain blocked the Na+ ‐dependent (stimulated) component of synaptosome fraction protein synthesis in the presence of 25mm‐K+. Ouabain inhibition was not alleviated by addition of ADP or ATP. 100μm‐atractylate failed to influence [3H]leucine uptake or incorporation. Synergistic inhibition by ouabain was observed with the cycloheximide‐sensitive component of protein synthesis and the chloramphenicol sensitive phase. Increasing the medium Ca2+ concentration stimulated protein synthesis and this stimulated component was inhibited by ouabain. Ouabain inhibition was associated with decreasing intraterminal K+ concentration and [K]i was linearly related to the protein synthesis rate in control and ouabain treated preparations.
DETERMINATION OF SOME MOLECULAR PARAMETERS OF TRYPTOPHAN HYDROXYLASE FROM RAT MIDBRAIN AND MURINE MAST CELL
Authors: Kuhn Donald M. , Rosenberg Robert C. , Lovenberg Walter
Published: October 2006

—The molecular parameters of tryptophan hydroxylase (EC 1.14.16.4) from rat midbrain and murine mast cell were determined by gel filtration and sucrose density gradient ultracentrifugation. The enzyme from rat midbrain has a calculated molecular weight of 220, 000, a Stokes radius of 55.6 Å, a frictional ratio of 1.28, and a sedimentation coefficient of 9.63 S. The mast cell enzyme has a calculated molecular weight of 144, 000, a Stokes radius of 50.3 Å, a frictional ratio of 1.35, and a sedimentation coefficient of 6.97 S. It appears that the tryptophan hydroxylase species from rat midbrain and murine mast cell represent distinct molecular entities.
INHIBITION OF GUINEA‐PIG BRAIN TYROSINE HYDROXYLASE BY CATECHOLS AND BIOPTERIN
Authors: Mann S. P. , Gordon J. I.
Published: October 2006

—The inhibition by catechols and biopterin of tyrosine hydroxylase from guineapig caudate nuclei has been examined. Inhibitory constants of 10–20 μm were obtained for dopamine and noradrena‐line and 150–250 μmfor l‐DOPA and dihydroxyphenylacetic acid. When examined under similar conditions homovanillic acid was found not to be inhibitory. Using an acetone dried powder as the source of tyrosine hydroxylase no change in Km or Vmax was observed when cyclic AMP or Ca2+ were added to the medium. Enzyme mechanisms and a possible explanation of the mechanisms controlling catechol synthesis are discussed.