bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chronic Hyperphenylalaninemia Produces Cerebral Hyperglycinemia in Immature Rats
Authors: Dienel Gerald A. 
Published: October 2006

Abstract:The amino acid content of three tissues was measured in 10‐day‐old rats made hyperphenylalaninemic from age 3 to 10 days by daily injections of phenylalanine plus α‐methylphenylalanine to inhibit phenylalanine hydroxylase (PAH). At 12 h after the last injection, the concentrations of alanine, valine, methionine, isoleucine, and leucine in the cerebral hemispheres were depressed by 25–50%, whereas that of glycine was elevated 2.3‐fold. In the spinal cord, the levels of phosphoserine, methionine, and leucine were decreased by 40–50%, and those of serine and threonine increased by 50%. Tyrosine and phenylalanine concentrations were high in all tissues, 2–3 and 15–30 times normal, respectively; of the amino acids investigated, they were the only ones changed in the liver. Cerebral hyperglycinemia was also produced by chronic treatment with phenylalanine plus p‐chlorophenylalanine to inhibit PAH, but not by acute (12 h) hyperphenylalaninemia. An increase in cerebral phosphoserine phosphatase activity was greater in rats treated with phenylalanine plus PAH inhibitor than with inhibitor alone. The content of brain glycine normally declines with age from birth to 15 days; this decrease was prevented by chronic hyperphenylalaninemia. Attempts to reduce the cerebral glycine content of the hyperphenylalaninemic rats were unsuccessful. However, one of the therapeutic protocols, methionine loading, may be useful because it increased the methionine and decreased the phenylalanine contents in the brain.
Regional Distribution and Production Rate of 3‐Methoxy‐4‐Hydroxyphenylethyleneglycol Sulphate (MHPG‐SO4) in Rat Brain
Authors: Kohno Yasuko , Tanaka Masatoshi , Nakagawa Ryoichi , Toshima Nobuo , Nagasaki Nobuyuki 
Published: October 2006

Abstract:The levels of noradrenaline (NA) and 3‐methoxy‐4‐hydroxyphen‐ylethyleneglycol sulphate (MHPG‐SO4) in 15 brain regions showed a parallel distribution in male Wistar rats. The differences in regional distribution of MHPG‐SO4 were similar to those in the rate of NA turnover reported by other investigators. The accumulation rates of MHPG‐SO4 during 45 and 90 min after probenecid injection significantly correlated to the steady state levels of MHPG‐SO4 in nine regions studied. With the results, the regional levels of MHPG‐SO, either in untreated or in probenecid‐treated rats, are considered to be a useful index of NA turnover.
[3H] Diazepam Displacing Activity in Human Cerebrospinal Fluid
Authors: Kuhn Wilfried , Neuser Dieter , Przuntek Horst 
Published: October 2006

Abstract:Pooled human cerebrospinal fluid was separated by Sephadex G‐50 chromatography. The presence of three peaks, A, B and C, was demonstrated by monitoring absorbance at 254 and 280 nm. All peaks showed [3H]diazepam displacing activity in the membrane receptor test. Peak B was further separated on Bio‐Gel P‐4. At least two major fractions free of salt and GABA in the molecular weight range of approximately 700‐3600 were shown to displace [3H]diazepam in the receptor test. This activity was enhanced by a factor of 3 in the presence of 10 μm‐GABA.
Anticonvulsant Activity of Glycylglycine and δ‐Aminovaleric Acid: Evidence for Glutamine Exchange in Amino Acid Transport
Authors: Samuels Stanley , Fish Irving , Schwartz Stephen A. 
Published: October 2006

Abstract:We have proposed that glutamine serves in a facilitated diffusion process, mediated by the enzyme γ‐glutamyl transferase (γ‐glutamyl transpeptidase; γGT) and that it leaves the brain in exchange for entering amino acids. Glutamine is also a precursor of γ‐aminobutyric acid (GABA). Thus, providing an alternate substrate for γGT should spare brain glutamine, raise GABA, and cause an anticonvulsant effect. We have found that glycylglycine, the best‐known substrate for γGT, and δ‐aminovaleric acid (DAVA), a structural analog, have anticonvulsant activity in DBA/2J mice. Both compounds can decrease the incidence and severity of seizures induced by l‐methionine‐rs‐sulfoximine or electroconvul‐sive shock. DAVA was also tested and found to be active against seizures caused by pentylenetetrazol or picrotoxin. [14C]DAVA entered the brain at the rate of 18.7 nmol/g/min. The activity of DAVA as a substrate of γGT was intermediate to that of glycylglycine and glutamine. Preliminary studies have shown that brain glutamine and perhaps GABA are elevated 3 h after administration of DAVA (7.5 mmol/kg). These findings support the theory that glutamine exchange plays a role in amino acid transport across the blood‐brain barrier and suggests a new concept in anticonvulsant therapy. Key Words: Amino acids, transport—γ‐Aminobutyric acid—δ‐Amino valeric acid—Anticonvulsant—Glutamine, exchange—Seizures.
ß‐Adrenergic Receptor Activation Increases Acetylcholine Receptor Number in Cultured Skeletal Muscle Myotubes
Authors: Blosser James C. 
Published: October 2006

Abstract:Treatment of embryonic chick muscle myotubes with the ß‐adrenergic agonist isoproterenol increased the number of surface membrane nicotinic cholinergic receptors. Receptor degradation was unaffected by isoproterenol, suggesting that receptor synthesis was increased. The effect of isoproterenol appears to be mediated by the ß‐adrenergic receptor adenylate cy‐clase system for the following reasons: (a) The response to isoproterenol was dose‐dependent and stereospecific. (b) The response to catecholamines followed the order isoproterenol > epinephrine > norepinephrine. (c) Al‐prenolol, a ß‐adrenergic antagonist, but not phen‐tolamine, an a‐antagonist, abolished the effect, (d) The maximal effects of isoproterenol and cholera toxin, an activator of adenylate cyclase, were not additive. These results suggest that under certain physiological states catecholamines may play an important role in the regulation of cholinergic receptors.
Comparative Thermodynamics of Benzodiazepine Receptor Ligand Interactions in Rat Neuronal Membranes
Authors: Doble Adam 
Published: October 2006

Abstract:The effects of temperature on the interaction of various ligands with the benzodiazepine receptor were studied in rat brain membrane preparations. The affinities of all ligands studied were reduced on raising the temperature from 4 to 37°C. The variation of affinity constant with temperature deviated from the classical relationship for both the anticonvulsant ligand [3H]flunitrazepam and the proconvulsant ligand [3H]ethyl β‐carboline‐3‐carboxylate. This imples a variation of observed enthalpy change of binding with temperature. Possible reasons for this are discussed. γ‐Aminobutyric acid and sodium chloride both enhance the binding of [3H]flunitraze‐pam—the former by an increase in the entropic component of the binding energy, and the latter by an increase in the enthalpic component. In a series of ligands of different biological activities, no simple correlation was observed between biological activity and temperature dependence of binding.
The S100‐b Protein: Tyrosine Residues Do Not Exhibit an Abnormal Fluorescence Spectrum
Authors: Baudier Jacques , Gérard Dominique 
Published: October 2006

Abstract:The β subunit of the bovine brain S100‐b protein (ββ) lacks tryptophyl residue but contains one tyrosine. Our experiments show that this protein is characterized by a typical tyrosine fluorescence spectrum, with a maximum at 303 nm. Identical fluroescence properties were found for the rat brain S100‐b protein. Comparison with the fluorescence spectrum of the bovine brain S100‐a’ protein (α'β), which contains a tryptophan residue in the α’ subunit, enables us to demonstrate that the recent report describing an abnormal fluorescence spectrum for the bovine brain S100‐b protein may result from a contamination of the S100‐b by the S100‐α’ protein.
Comparative Characterization of Glutamate Decarboxylase in Crude Homogenates of Oviduct, Ovary, and Hypothalamus
Authors: Erdő Sándor L. , Kiss Béla , Szporny László 
Published: October 2006

AbstractSome biochemical characteristics of l‐glutamate decarboxylase (GAD) were compared using crude homogenates of the rat oviduct, ovary, and hypothalamus. As estimated by the measurement of CO2 production, the specific activities of oviductal and ovarian GAD were about 10 and 3% of the hypothalamic value, respectively. Stoichiometric formation of γ‐aminobutyric acid (GABA) and CO2 from l‐glutamate could be observed in oviduct and hypothalamus, while in ovarian homogenates the production of C02 was more than nine times that of GABA. Hypothalamic and tubal GAD showed similar time course, temperature dependence, and pH dependence. The dependence on protein concentration and on exogenous cofactor supply was also similar in these two tissues. The kinetic constant for l‐glutamate as a substrate was nearly the same in oviduct (1.30 mM) and hypothalamus (1.64 mM). The responsiveness of tubal and hypothalamic GAD to various inhibitors was also similar. The present findings indicate that the oviductal and the hypothalamic GAD may be identical, and they suggest a possible GABAergic innervation of the Fallopian tube.
Modulation of Phosphorylation of a 30‐kD Polyribosomal Protein (pp30) by ACTH and Spermine: Comparison with Modulation of Brain Protein Synthesis
Authors: Schrama L. H. , Frankena H. , Edwards P. M. , Schotman P. 
Published: October 2006

AbstractGel electrophoretic separation of proteins phosphorylated in a postmitochondrial supernatant fraction of brain in the presence of spermine or adrenocorticotropin (ACTH) indicated modulation in only one region (30 kD) of the gel. The 30‐kD (pp30) protein together with enzyme activity catalyzing its phosphorylation and sensitivity of the phosphorylation to spermine and ACTH were retained in a free polyribosomal fraction of this extract. ACTH(11–24) inhibited phosphorylation at all the spermine or Mg2+ concentrations tested. Structure‐activity studies revealed that the inhibitory activity within ACTH(l–24) resides in the sequences ACTH(11–24), (5–18,17Lys,18Lys)‐NH2, (15–24), (7–16)‐NH2, and (1–16)‐NH2 and can also be found in certain polylysine fragments. Phosphorylation under conditions suitable for measuring protein synthesis revealed only one phosphoprotein (pp30), sensitive to both ACTH(15–24) and spermine. The possibility of a relationship between modulation of pp30 phosphorylation and modulation of brain cell‐free protein synthesis is discussed in relation to the effects of ACTH, spermine, and Mg2+ .
Photoaffinity Labeling of Different Benzodiazepine Receptors at Physiological Temperature
Authors: Eichinger A. , Sieghart W. 
Published: October 2006

AbstractIrreversible labeling of benzodiazepine receptors in membranes from cerebellum or hippocampus was compared at 0°C or 37°C using [3H]flunitrazepam as a photoaffinity ligand. [3H]Flunitrazepam reproducibly and irreversibly labeled mainly one protein (P51) in cerebellum and at least two proteins (P51 and P55) in hippocampus at both temperatures. Differential inhibition at 37°C of irreversible [3H]flunitrazepam binding to the individual proteins by several selective benzodiazepine receptor ligands supports the hypothesis that P51 and P55 are associated with different benzodiazepine receptors.
Comparative Ontogenesis of Brain Tryptamine, Serotonin, and Tryptophan
Authors: Artigas F. , Suñol C. , Tusell J. M. , Martínez E. , Gelpí E. 
Published: October 2006

Abstract:The pattern of ontogenetic development of tryptophan (TP), tryptamine (T), indole‐3‐acetic acid (IAA), 5‐hydroxytryptamine (5‐HT; serotonin), and 5‐hydroxyindole‐3‐acetic acid (5‐HIAA) in the brains of rats aged 1–45 days is presented. Analysis of the five components in each brain allows the calculation of the acid/amine and amine/amino acid ratios. These metabolic indexes are a useful tool to study and compare the metabolic origins and fates of both amines. The ontogenetic patterns of TP, T, and IAA are very similar, especially during the first week postpartum. The highest and lowest levels found for T were 2.2 ng/g and 0.1 ng/g at the 1st and 5th day, respectively. The temporal relationship between the T/TP and IAA/T ratios suggests the existence of mechanisms protecting T against monoamine oxidase (MAO) which develop in parallel to synaptogenesis. Significant correlations were found between TP and IAA during the whole period studied and between TP and T during the first week after birth. The 5‐HT peak found during the first postpartum week could be due to a non‐neuronal pool of 5‐HT protected against MAO and possibly contained in mast cells. Preliminary determinations on leptomeningeal membranes suggest the existence of such a pool.
Protein Turnover in Brain of the Rat Fetus
Authors: Johnson John D. 
Published: October 2006

Abstract:Protein synthesis in vivo was studied in whole brain of rat fetuses using continuous intravenous infusion of L‐[U‐14C]tyrosine into unrestrained pregnant rats at 19 and 21 days gestation. Protein degradation (KD) was calculated by subtracting fractional growth rate of brain protein (KG) from the fractional synthesis rate (Ks). Ks was high at both gestational ages (0.42 ± 0.03 days−1 at day 19, 0.47 ± 0.029 days−1 at 21 days), comparable to values previously reported for newborn rat cerebral hemispheres, and threefold higher than is seen in adult animals. KD was similar at both 19 and 21 days gestation (0.19‐0.24) and lower than that reported in neonatal rat brain using similar techniques. Protein accretion during the most rapid phase of brain growth (fetus) is accomplished by similar rates of protein synthesis, but decreased rates of degradation when compared with a slower growth phase (newborn). KD in the brain of the rapidly growing fetus is slightly higher than in adult cerebral hemispheres.
Regional Mitochondrial Respiratory Activity in Huntington's Disease Brain
Authors: Brennan William A. , Bird Edward D. , Aprille June R. 
Published: October 2006

Abstract:This study investigated mitochondrial respiratory activity in Huntington's disease (HD) brain. Mitochondrial membranes from caudate and cortex of HD and non‐HD autopsied brains were assayed for succinate oxidation, cytochrome oxidase activity, and cytochromes b, cc1, and aa3. There was a significant decrease in HD caudate mitochondrial respiration, cytochrome oxidase activity, and cytochrome aa3, whereas cytochromes b and cc1 were normal. These findings are consistent with the hypothesis that mitochondrial dysfunction may contribute to the localized hypometabolism and progressive atrophy of the HD caudate.
[3H]Nitrendipine Binding to Calcium Channels in Bovine and Rat Pituitary
Authors: Titeler Milt , De Souza Errol B. , Kuhar Michael J. 
Published: October 2006

Abstract:[3H]Nitrendipine was used to label sites in homogenates of bovine anterior and neurointermediate lobes of the pituitary gland. The amount of specific binding in the anterior lobe was 1.82 < 0.30 pmol/g wet weight of tissue and the KD was 1.44 < 0.02 x 10−10M. Preliminary experiments indicated a similar amount of binding in bovine neurointermediate lobe. In competition studies nimodipine and nisoldipine (two potent voltage‐sensitive calcium channel blockers) displayed IC50 values of 1.6 and 6.8 x 10−10M, respectively. Verapamil and the verapamil‐like calcium channel blockers D‐600 and tiapamil competed in a complex manner for the [3H]nitrendipine specific binding to bovine anterior pituitary homogenates. Autoradiographical studies demonstrated specific [3H]nitrendipine binding sites distributed approximately equally in the anterior and posterior lobes, but not in the intermediate lobe of the rat pituitary. In general the properties of [3H]nitrendipine binding in the pituitary tissue resemble strongly the properties of [3H]nitrendipine binding in the brain which is believed to be to voltage‐sensitive calcium channels. These results provide support for the hypothesis that calcium channels are involved in pituitary hormone secretion and that drugs that interact with calcium channels may modulate the secretory process directly at the level of the pituitary.
An Immunoglobulin M Monoclonal Antibody, Recognizing a Subset of Acetylcholinesterase Molecules from Electric Organs of Electrophorus and Torpedo, Belongs to the HNK‐1 Anti‐Carbohydrate Family
Authors: Bon Suzanne , Méflah Khaled , Musset Frédérique , Grassi †Jacques , Massoulié Jean 
Published: October 2006

Abstract:An immunoglobulin M (IgM) monoclonal antibody (mAb Elec‐39), obtained against asymmetric acetyl‐cholinesterase (AChE) from Electrophorus electric organs, also reacts with a fraction of globular AChE (amphiphilic G2 form) from Torpedo electric organs. This antibody does not react with asymmetric AChE from Torpedo electric organs or with the enzyme from other tissues of Electrophorus or Torpedo. The corresponding epitope is removed by endoglycosidase F, showing that it is a carbohydrate. The subsets of Torpedo G2 that react or do not react with Elec‐39 (Elec‐39+ and Elec‐39‐) differ in their electrophoretic mobility under nondenaturing conditions; the Elec‐39+ component also binds the lectins from Pisum sativum and Lens culinaris. Whereas the Elec‐39‐ component is present at the earliest developmental stages examined, an Elec‐39+ component becomes distinguishable only around the 70‐mm stage. Its proportion increases progressively, but later than the rapid accumulation of the total G2form. In immunoblots, mAt Elec‐39 recognizes a number of proteins other than AChE from various tissues of several species. The specificity of Elec‐39 resembles that of a family of anti‐carbohydrate antibodies that includes HNK‐1, L2, NC‐1, NSP‐4, as well as IgMs that occur in human neuropathies. Although some human neuropathy IgMs that recognize the myelin‐associated glycoprotein did not react with, Elec‐39+ AChE, mAbs HNK‐1, NC‐1, and NSP‐4 showed the same selectivity as Elec‐39 for Torpedo G2 AChE, but differed in the formation of immune complexes.
Conservation of Amino Acid Sequences Between Human and Porcine Choline Acetyltransferase
Authors: Hersh Louis B. , Takane Karen , Gylys Karen , Moomaw Carolyn , Slaughter Clive 
Published: October 2006

Abstract: The amino acid sequence of 11 peptides generated from human placental choline acetyltransferase was compared to the corresponding amino acid sequences predicted from the nucleotide sequence of a recently cloned porcine choline acetyltransferase cDNA. These peptides, which were generated by cyanogen bromide cleavage or tryptic digestion, accounted for 23% of the amino acids in the enzyme. Of the 145 amino acids sequenced eight differed between the two species, yielding an identity of 94% over the regions sampled.Of the eight amino acids that differed six could represent single base changes in the DNA sequence. These findings demonstrate strong sequence similarity between porcine and human choline acetyltransferase and indicate that they are closely related evolutionarily.
Characterization of a Cytosolic Protein (P36) Isolated from Pig Brain by Benzodiazepine‐Affinity Chromatography
Authors: Kirkness Ewen F. , Turner Anthony J. 
Published: October 2006

AbstractBenzodiazepine‐affinity chromatography, on a column of 1012S‐Sepharose, resulted in the detection and purification of a binding protein (P36) from the cytosolic fraction of pig cerebral cortex. Purified P36 was enriched over 3,500‐fold in a single step and was recovered with an efficiency of 50–60%. Analysis of the purified preparation by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis demonstrated a single polypeptide of Mr 36,000. TheStokes radius (3.44 nm) and sedimentation coefficient (4.43S) indicated that purified P36 is a dimeric protein. Analysis of the amino acid composition of P36 revealed a relatively high content of the hydrophobic amino acids, valine and leucine. Immunoblotting of several pig tissue preparations with an antiserum raised against purified P36 demonstrated approximately equal enrichment of P36 in cerebral cortex, cerebellum, and adrenal glands. Lesser enrichment was observed in kidney and liver, whereas a number of other tissues displayed no immunoreactivity. The γ‐aminobutyrate/benzodiazepine receptor complex and P36 showed no immunological cross‐reactivity. High‐affinity binding activity for [3H]Ro 15–4513, [3H]flunitrazepam, or [3H]PK11195 was not detected in preparations of purified P36. However, the ability of the γ‐aminobutyrate/benzodiazepine receptor inverse agonists, methyl‐ and ethyl‐#bT‐carboline‐3‐carboxylate, to inhibit the binding of P36 to 1012S‐Sepharose at relatively low concentrations indicates that P36 exhibits a degree of binding specificity.
Chemical and Surgical Lesions of Rat Olfactory Bulb: Changes in Thyrotropin‐Releasing Hormone and Other Systems
Authors: Sharif N. A. 
Published: October 2006

AbstractStereotaxic injection of kainic acid (15 μg) into rat olfactory bulbs was accompanied by a 53% (n = 4; p < 0.02) depletion of endogenous thyrotropin‐releasing hormone (TRH) as compared to sham‐operated controls 2 weeks postlesion. TRH levels remained unaltered in three other caudal regions. Bulbar kainate lesions produced a 58% (n = 5; p < 0.001) decrease in TRH receptor binding capacity without affecting the receptor affinity. Kainate lesions also reduced bulbar muscarinic and benzodiazepine receptors by 60% and 48%, respectively. Again, no changes in TRH receptors were apparent in six other brain areas after bulbar kainate treatment. Injection of the dopaminergic neurotoxin, 6‐hydroxydopamine (8 μg), into rat bulbs decreased TRH receptors by 35% (n = 4; p < 0.05) 1 week postlesion. One month after surgical bulbectomy, TRH and TRH receptor levels in a number of brain areas were unaltered compared to those of control animals. These studies suggest that TRH in the olfactory bulb originates intrinsically and may be produced predominantly for local use. Secondly, TRH receptors in the bulb appear to be postsyn‐aptically localized on intrinsic neurons, although a small proportion are also associated with presynaptic elements of dopaminergic noradrenergic neurons. Bulbar TRH receptors exhibited nanomolar affinity and a pharmacological selectivity akin to that of the pituitary gland and other brain regions.
Assay of 2‐Hydroxyputrescine in Various Regions of Rat Brain by Gas Chromatography‐Mass Spectrometry
Authors: Noto Tadashi , Hasegawa Takeshi , Hashimoto Hiromichi , Nakajima Teruo 
Published: October 2006

Abstract2‐Hydroxyputrescine in seven regions of single rat brains was measured with a sensitive, specific assay by gas chromatography‐mass spectrometry. The regions were the cerebral cortex, cerebellum, medulla oblongata, hypothalamus, striatum, hippocampus, and midbrain. The level of 2‐hydroxyputrescine was very high in the cerebral cortex and cerebellum, high in the medulla oblongata, hypothalamus, and hippocampus, and low in the striatum and mid‐brain. The level of 2‐hydroxyputrescine in the cerebellum was significantly higher than in the striatum and midbrain.
A 140‐Kilodalton Protein Is Released from Cultured Astrocytes by Phosphatidylinositol Phospholipase C
Authors: Amblard F. , He J.‐T. , Barbet J. , Goridis C. , Prochiantz A. 
Published: October 2006

AbstractAstrocytes in culture synthesize a 140‐kilodalton (140‐kD) protein (protein 140) that is released into the medium on incubation with phosphatidylinositol phospholipase C. This molecule therefore belongs to the class of proteins anchored to the external side of the cell membrane through a glycolipid moiety. Protein 140 is present in astrocyte cultures derived from two different regions of the brain and is not expressed by neurons in vitro. It differs from neuronal cell adhesion molecule 120 or 140 and is probably identical to a protein of 140 kD present in C6 glioma cells.