bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECT OF CALCIUM ON GANGLIOSIDE SOLUBILITY
Authors: Kruger S. , Mendler M. 
Published: October 2006

Abstract—Gangliosides were extracted by various procedures from acetone powder prepared from grey matter of cattle brain. The mixtures of gangliosides, containing 24–26% N‐acetylneuraminic acid (NANA), were dissolved in chloroform‐methanol. Upon addition of aqueous solutions of Ca2+, the amount of gangliosides (and Ca2+) passing into the lower phase of the two‐phase solvent system was a linear function of the product of the initial concentrations of Ca2+ and ganglioside‐NANA. It was also a function of the initial stoichiometric ratios of ganglioside‐NANA to Caa+. In accordance with previous reports, no gross differences of composition between the initial mixture of gangliosides and the calcium‐solubilized portion could be detected by glass‐fibre chromatography.
LIPID METABOLISM IN BRAIN TISSUE EXPLANTS1
Authors: Menkes J. H. 
Published: October 2006

Abstract— Tissue explants from frontal lobes of rat brain were used for the study of cerebral fatty acid metabolism. After tissues had been maintained in serum‐supplemented medium, a lipid‐free medium was substituted and metabolic studies were carried out. Under these conditions explants continued to take up lipid precursors for at least 48 h, as judged by incorporation of dl‐[2‐14C]mevalonic acid into cellular lipids. [l‐14C]Stearic acid and [l‐14C]palmitic acid were bound to cells as the free fatty acids, or incorporated into neutral lipids (particularly triglycerides), glycolipids and phospholipids. In the galactolipid fraction, cerebrosides were the principal radioactive lipids. Choline phosphoglycerides, ethanolamine phosphoglycerides, inositol phosphoglycerides and serine phosphoglycerides were the principal radioactive phospholipids. Fatty acids were incorporated into cellular lipids either unchanged or after desaturation, chain elongation, or both. Maximum incorporation of stearate occurred in tissues derived from 3‐day‐old animals. With increasing age the uptake of fatty acid dropped sharply.When the labelling of lipids as a function of time was followed in 3‐day‐old animals, triglycerides and choline phosphoglycerides were the first fractions to take up labelled stearate. Labelling of cerebrosides occurred slowly, only becoming evident after 24 h. These studies exemplify the usefulness of tissue explants for prolonged metabolic studies in normal and pathological specimens of brain.
INCREASED CEREBRAL EXCITABILITY CAUSED BY p‐CHLOROPHENYLALANINE IN YOUNG RATS
Authors: Prichard J. W. , Guroff G. 
Published: October 2006

Abstract—Single intraperitoneal doses of p‐chlorophenylalanine (p‐CP; 100 mg/kg or more), lowered the threshold of flurothyl‐induced seizures in 1‐ and 2‐week old rats after 24 h, but not after 4 or 72 h. In older rats there was no change in cerebral excitability after a single dose, but the seizure threshold was lowered after several daily doses. Rats given p‐CP in lower doses daily from birth exhibited lowered seizure thresholds only until 3‐4 weeks of age.Depletion of brain serotonin and inhibition of liver phenylalanine hydroxylase by p‐CP exhibited time courses and dose responses similar to those reported for older animals. Activity of phenylalanine hydroxylase returned to normal more rapidly than the content of serotonin after a dose of p‐CP, and recovery of normal seizure threshold seemed to be more closely associated with recovery of the hepatic enzyme than with restoration of the brain amine. It appears, therefore, that hyperphenylalanemia or some consequence of it may be an important factor contributing to increased cerebral excitability in p‐CP intoxication and possibly in clinical phenylketonuria and that depletion of brain serotonin may not be the only or even the predominant cause of the changes in cerebral excitability in these conditions.
THE EFFECTS OF UNDERNUTRITION UPON THE ENERGY RESERVE OF THE BRAIN AND UPON OTHER SELECTED METABOLIC INTERMEDIATES IN BRAINS AND LIVERS OF INFANT RATS1
Authors: Thurston Jean Holowach , Prensky A. L. , Warren Sheila K. , Albone K.‐R. 
Published: October 2006

Abstract—Rats undernourished from the first to the ninth day of life exhibited no decrease in the energy reserve (P‐creatine, ATP, glucose and glycogen) of the brain, although they underwent a 41 per cent decrease in body weight. The apparent increase in the cerebral levels of glucose‐6‐phosphate and the decreases in hepatic glucose and lactate in the starved animals were probably a consequence of the fact that they froze faster than the control animals rather than of any essential differences in vivo. However, decreases in cerebral glutamate (11 per cent) and hepatic glutamate (33 per cent) in the undernourished animals cannot be explained on this basis. Possible explanations for this decrease in cerebral glutamate content are: a decreased supply of glutamate from the liver, a decreased synthesis of glutamate by the brain, or an increased use of glutamate as an energy source. Since levels of glutamate in the brain increase progressively during the first weeks of life, another interesting possibility is that the lower level of cerebral glutamate in undernourished rats represents a biochemical indicator of a delay in the maturation of specific morphological components which are rich in glutamate and are characteristic of the brain.
A SENSITIVE RADIOIMMUNOASSAY FOR 7S NERVE GROWTH FACTOR ANTIGENS IN SERUM AND TISSUES
Authors: Johnson D. G. , Gorden P. , Kopin I. J. 
Published: October 2006

Abstract—A radioimmunoassay was developed which can measure accurately concentrations of mouse 7S nerve growth factor antigens (NGFA) as low as 3·0 ng/ml in serum or tissue homogenates. Extremely large amounts of presumed nerve growth factor were found in the submaxillary gland; but considerable quantities were also present in mouse serum, kidney, adrenal gland and vas deferens. Heart, spleen, liver and muscle contained less of the presumed nerve growth factor, and only small amounts were recovered from brain. Rat adrenal gland and serum from rats, guinea pigs and man contained much less immunologically reactive material. The level of presumed nerve growth factor in the mouse heart was highest at birth and decreased slowly during maturation. In the mouse submaxillary gland the content of presumed nerve growth factor increased rapidly after 2 weeks of postnatal age, with higher levels found in male animals. Destruction with 6‐hydroxydopamine of the sympathetic nerves in the hearts of newborn or adult mice did not significantly alter the amount of presumed nerve growth factor recovered in the heart.
THE LABELLING OF THE GANGLIOSIDIC FRACTION FROM BRAINS OF RATS EXPOSED TO DIFFERENT LEVELS OF STIMULATION AFTER INJECTION OF [6‐3H]‐GLUCOSAMINE
Authors: Maccioni Alicia H. R. , Giménez María Soffía , Cuputto R. 
Published: October 2006

Abstract—[6‐3H] Glucosamine was injected into rats and then they were submitted for 1 h to light (about 1100 lux) and sound, while their controls were kept in darkness. Two series of experiments were done: in one, the animals received the injection intracerebrally; in the other, the injection was intraperitoneal. In both series the ratios of specific radioactivities (c.p.m./μmol of NANA) in mitochondria1 gangliosidic fractions to those in synaptosomal gangliosidic fractions were higher for rats exposed to illumination and sound −+ 74 per cent, P < 0·01 and + 49 per cent, P < 0·001 (in respectively, experiments with intracerebral and intraperitoneal injections) than for animals kept in dark. For animals iqjected intraperitoneally the specific radioactivity of the mitochondria1 gangliosidic fraction from rats exposed to light was higher (+ 11 per cent, P < 0.05) than that obtained from animals kept in dark. For synaptosomes the specific radioactivity of the gangliosidic fraction obtained from animals exposed to light was lower (−15 per cent, P < 0.01) than that obtained from animals kept in dark.In animals kept under the experimental conditions already described for more than 1 h the differences tended to disappear. No differences were observed between the two groups of rats in the amounts of radioactivity found in the brain.
THE EFFECTS OF PHENYLPYRUVATE AND HYPERPHENYLALANINEMIA ON INCORPORATION OF [6‐3 H]GLUCOSE INTO MACROMOLECULES OF SLICES OF RAT CEREBRAL CORTEX1
Authors: Glazer R. I. , Weber G. 
Published: October 2006

Abstract—The effects of phenylpyruvate and hyperphenylalaninemia on the incorporation of [6‐3H]glucose into lipids, proteins and nucleic acids were examined in differentiating and adult rat brain. Foetal brain was most sensitive to inhibition by phenylpyruvate in vitro, with significant effects occurring at 2·5 mM for labelling of lipids and proteins and at 5 mM for labelling RNA and DNA. Older age groups were less affected, and cortical slices from adult brain were slightly or not at all affected by phenylpyruvate.The inhibition by phenylpyruvate of incorporation of [6‐3H]glucose into nucleic acids, proteins, and lipids could be further distinguished by the reversibility of the effect on nucleic acid and protein synthesis at high levels of glucose and the irreversibility of the effect on lipid synthesis. Lipid synthesis was most sensitive to inhibition by phenylpyruvate at the stage of fatty acid synthesis, with lesser effect on the formation of glyceride glycerol.Exposure in utero of the foetal brain to maternal hyperphenylalaninemia resulted in reduction of 26–38 per cent in the subsequent incorporation in vitro of [6‐3H]glucose into lipids, proteins, RNA and DNA of brain slices from foetal animals. Feeding hyperphenylalaninemic pregnant rats a high‐glucose diet significantly protected the foetal brain from the neurotoxicity accompanying the hyperphenylalanemia.
ANTIGEN—ANTIBODY CROSSED ELECTROPHORESIS OF WATER‐SOLUBLE RAT BRAIN ANTIGENS
Authors: Bock Elisabeth , Mellerup E. T. , Rafaelsen O. J. 
Published: October 2006

Abstract—A method of separation by antigen‐antibody crossed electrophoresis was applied to the study of water‐soluble rat brain antigens. Five different rat brain preparations were used as antigens for immunization. The extract from Triton X‐100 treated brains gave the best antibody response. An antiserum containing 27 precipitating antibodies was obtained. The preparation of antigens for immunoelectrophoresis was investigated. Treatment with demineralized water gave the highest number of antigen‐antibody precipitates. Treatment with detergents and sonication gave a higher total protein yield, but the number of precipitates was unaffected.
THE EFFECT OF BICUCULLINE, METRAZOL, PICROTOXIN AND STRYCHNINE ON THE RELEASE OF [3H]GABA FROM RAT BRAIN SLICES
Authors: Johnston G. A. R. , Mitchell J. F. 
Published: October 2006

Abstract—Each of the four convulsants used significantly influenced the release of [3H]‐GABA from brain slices, without affecting [3H]GABA uptake. Bicuculline (10−5M, but not 10‐fold higher or lower concentrations) potentiated the electrically evoked release of [3H]GABA but not the resting release, whereas metrazol (10−4 to 10−6 M) was found to inhibit resting but not electrically evoked release. Strychnine (10−4 and 10−5 M) and picro‐toxin (10−4 M) inhibited electrically evoked release.
STRUCTURAL AND BIOCHEMICAL MATURATION OF THE CEREBRAL PALLIUM IN RABBIT FETUSES: MORPHOGENESIS AND LIPIDS
Authors: Dekaban A. S. , Patton V. M. , Cain D. F. 
Published: October 2006

Abstract—Morphological parameters of maturation of the cerebral pallium in rabbit fetuses ranging between 20 days of gestation (d.g.) and the early neonatal stage are expressed semi‐quantitatively and correlated with progressive changes in the brain lipids, glycolipids and nucleic acids. Dual expression of the chemical values, using as referents both the dry weight of the tissue and the DNA unit, reveal the crucial stage in brain development when rapid cell proliferation is replaced by rapid cell growth; this stage in rabbit fetuses occurred between 28 and 30 d.g. Between 20 d.g. and the early neonatal phase the RNA decreased moderately when expressed per unit of DNA. Even at the time of term birth the cortical nerve cells of the rabbit showed signs of immaturity including a relatively small nuclear volume.On the dry weight basis, the lipids of the cerebral pallium exhibited little change in composition during fetal development; however, cerebrosides rose substantially between 30 d.g. and the early neonatal phase. When expressed per unit of DNA, all lipids and glycolipids continued to increase progressively in a pattern characteristic of growth throughout the prenatal period studied. This increase was also apparent when the lipid constituents were expressed per total pallium at the progressive gestational stages.The molar ratios of phospholipids:cholesterol:cerebrosides in the pallium of rabbits of different ages were as follows: in adult rabbits‐2.9: 2.6: 1.0, in the newborn‐2.9: 1.3: 0.2 and in the 30 d.g. fetuses‐3.0: 1.2:0.44. These values reflect the fact that during maturation the content of phospholipids changes little, whereas that of cholesterol and especially erebrosides increases markedly.
THE CIRCULAR DICHROISM OF SYNAPTOSOMAL MEMBRANES: STUDIES OF INTERACTIONS WITH NEUROPHARMACOLOGICAL AGENTS1
Authors: Moore W. V. , Wetlaufer D. B. 
Published: October 2006

AbstractThe circular dichroic spectrum of synaptosomal membranes was highly reproducible and qualitatively similar to that of erythrocyte membranes. The spectrum exhibited a minimum at 224 nm, a shoulder at 212 nm and a maximum at 195 nm. The mean molar ellipticity at the maximum and minimum was approximately +8000 and –8000 respectively. The protein components were the dominant source of the CD signal. Quantitative estimates showed negligible contributions to the spectrum from cholesterol, phosphatidyl serine and TV‐acyl sugars. Phospholine iodide, eserine, decamethonium, tetramethyl ammonium chloride and acetylcholine at concentrations of 10‐3 and 10‐4M did not produce detectable perturbations of the membrane circular dichroism. The circular dichroic spectrum of d‐tubocurarine exhibited a maximum at 198 nm and a minimum at 212 nm. Addition of d‐tubocurarine to membrane suspensions in the cuvette yielded a complex spectrum representing the result of a simple additive combination of the circular dichroic spectra of d‐tubocurarine and the membranes. However, preincubation of the membranes with 3 x 10‐3m d‐tubocurarine at 0‐4°C for 5‐10 min followed by sedimentation, several washes and resuspension resulted in a circular dichroic spectrum which appeared to involve no change in the membrane contribution, but there was a substantial decrease in the molar ellipticity of the d‐tubocurarine remaining with the membranes.
ACETYLCHOLINESTERASE IN DEVELOPING CHICK EMBRYO BRAIN
Authors: Iqbal Z. , Talwar G. P. 
Published: October 2006

Abstract–Acetylcholinesterase has been assayed at different stages of development to see whether changes in the activity of this enzyme are correlated in any way with the ontogenesis of electrical activity in the brain of growing chick embryo. The specific activity of the enzyme was highest in the synaptosomal fraction of the brain. The activity of the enzyme increased progressively with the age of the embryo. There were three isozymic forms of the enzyme in the 6‐day‐old embryo brain. A new isozyme appeared around the 9th day. The Km values of the enzyme for acetylthiocholine from 6‐ and 20‐day‐old embryo brains were 6.5 ± 10‐5m and 3.3 ± 10‐5m respectively. Enzyme preparations from 6‐day‐old embryos were found to lose 50 per cent of their activity when heated at 50°C for 10 min. Under similar conditions the loss in activity in 18‐day‐old embryo brain enzyme was 22 per cent.
CHANGES IN AMOUNT OF COLCHICINE‐BINDING PROTEIN (TUBULIN) IN RABBIT BRAIN DURING DEVELOPMENT1
Authors: Dedburn Dianna A. , Dahl D. R. 
Published: October 2006

AbstractColchicine binding was used as a measure of the levels of microtubule protein (tubulin) in several regions of rabbit brain during postnatal development. All regions studied showed a decrease in tubulin per mg of total protein; however, each region showed an increase in total tubulin from 1 day of age to adulthood. The net change in tubulin during development coincided with a proliferation of dendrites (which are rich in microtubules) and a decrease in microtubules from spindle apparatus, axons and astrocytes. We suggest that the total amount of tubulin changes in response to demands of the maturing brain cell for microtubules with different functional roles.
TRANSPORT AND TURNOVER OF NEUROHYPOPHYSIAL PROTEINS OF THE RAT
Authors: Norströ A. , Sjöstrand J. 
Published: October 2006

AbstractAxonal transport and turnover rate of proteins in the supraoptico‐neurohypo‐physial tract were studied after injection of 35S cysteine into the region of the supraoptic nucleus. The proximo‐distal migration of labelled proteins from the nerve cell bodies to the axon terminals in the neurohypophysis was followed by measuring the radioactivity of neurohypophysial proteins at various time intervals (4 h to 30 days) after isotope injection. A rapidly transported phase of proteins with a minimal transport rate of approximately 60 mm/day was demonstrated. An accumulation of protein‐bound radioactivity was also observed in the neural lobe at 9 days after isotope injection, representing slowly transported proteins (0‐5 mm/day). In addition, an intermediate phase of axonal transport (1‐5 mm/day) was found.Fractionation of neurohypophysial proteins by polyacrylamide gel disc electrophoresis revealed that a predominating portion of the radioactivity was recovered in a single protein component (fraction A) at 4 h as well as at 30 days after isotope injection. This protein component was shown to be a constituent both of the rapid and the slow phase of axonal transport. With time an increasing amount of radioactivity was found in another protein component (fraction B), which reached a maximum at 14 days after injection and then remained fairly constant up to 30 days.When the turnover rates of neurohypophysial proteins were estimated, a half‐life of 1‐2 days and 8 days was calculated for the rapidly and slowly transported proteins, respectively.
STUDY ON THE INHIBITION OF BRAIN GLUTAMATE DECARBOXYLASE BY PYRIDOXAL PHOSPHATE OXIME‐O‐ACETIC ACID
Authors: Tapia R. , Sandoval M. E. 
Published: October 2006

AbstractThe kinetics of the inhibition of mouse brain glutamate decarboxylase by pyri‐doxaI‐5′‐phosphate oxime‐O‐acetic acid (PLPOAA) was studied. The inhibition was noncompetitive with regard to glutamic acid; it could be partially reversed by pyridoxal phosphate, but only when the concentration of the latter in the incubation medium was higher than that of pyridoxal‐5′‐phosphate oxime‐O‐acetic acid. The inhibition produced by aminooxyacetic acid, which is remarkably greater than that produced by PLPOAA, was also partially reversed only when an excess of pyridoxal phosphate was added. Both in the presence and in the absence of a saturating concentration of pyridoxal phosphate, the activity of the enzyme was decreased by PLPOAA at a 10−4m concentration to a value of about 50 per cent of the control value obtained without added coenzyme. This activity could not be further reduced even when PLPOAA concentration was increased to 5 × 10−3m. This same minimal activity of glutamate decarboxylase was obtained after dialysis of the enzymic preparation, or after incubation with glutamic acid in the cold followed by filtration through Sephadex G‐25. The addition of pyridoxal phosphate to the dialysed or glutamic acid‐treated enzyme restored the activity to almost the control values. PLPOAA did not affect the activity of glutamate decarboxylase from E. coli or that of DOPA decarboxylase and GABA transaminase from mouse brain. To account for the results obtained it is postulated that brain glutamate decarboxylase has two types of active site, one with firmly bound, non‐dialysable pyridoxal phosphate and the other with loosely bound, dialysable coenzyme; PLPOAA behaves as a weak inhibitor probably because it can combine mainly with the loosely bound coenzyme site, while aminooxyacetic acid is a potent inhibitor probably because it can block both the ‘loosely bound coenzyme’ and the ‘firmly bound coenzyme’ sites.
ENZYMES OF NUCLEIC ACID METABOLISM IN THE BRAINS OF YOUNG AND ADULT RATS
Authors: Guroff G. , Brodsky Marcia 
Published: October 2006

AbstractA number of precursors of RNA are incorporated several‐fold more readily into the RNA of brain slices from 10‐day‐old rats than into RNA of slices from adult animals. The brains of the young animals show moderately higher levels of some of the anabolic enzymes of RNA metabolism including RNA polymerase (nucleosidetriphosphate: RNA nucleotidyltransferase; EC 2.7.7.6) and substantially lower levels of the degradative enzymes, the nucleoside phosphorylases. The data suggest that all the enzymes work in a concerted fashion to produce an increased rate of synthesis in young animals rather than that any single controlling enzymic event is responsible.
MECHANISM OF ACTION OF β‐N‐OXALYL‐L‐α, β‐DIAMINOPROPIONIC ACID, THE LATHYRUS SATIVUS NEUROTOXIN
Authors: Cheema P. S. , Padmanaban G. , Sarma P. S. 
Published: October 2006

AbstractThe source of ammonia in the brain tissue of young rats treated with β‐N‐oxalyl‐l‐α, β‐diaminopropionic acid (ODAP) has been studied. ODAP administration to 12‐day‐old rats causes a significant increase in the levels of adenylic acid deaminase in the brain. Glutaminase activity also shows an increase under these conditions. An increase in the levels of acid protease and transglutaminase is also observed in the brain of ODAP‐treated animals. Glutamate dehydrogenase activity is decreased slightly. Glutamine synthetase enzyme is not affected. Aspartate‐α‐ketoglutarate transaminase and aspartate‐pyruvate transaminase activities are enhanced in the brain tissue of ODAP‐treated rats. It is held that protein degradation, especially the cleavage of free and protein‐bound amide bonds, may be responsible for excess ammonia liberation in the brain of ODAP‐treated young rats.
TYROSINE HYDROXYLASE IN BOVINE CAUDATE NUCLEUS
Authors: Nagatsu T. , Sudo Y. , Nagatsu I. 
Published: October 2006

AbstractApproximately 80 per cent of tyrosine hydroxylase activity in bovine caudate nucleus was particle‐bound. The rest of the activity was found in the soluble fraction. The enzyme activity in crude tissue preparations was inhibited, probably by the presence of endogenous inhibitors. Dilution of crude tissue preparations such as the crude mitochondrial fraction caused an increase in the specific activity. The particle‐bound enzyme was solubilized by incubation with trypsin. The presence of deoxycholate increased the degree of solubilization. The activity of the solubilized enzyme from the washed particles was also inhibited, but the subsequent purification by ammonium sulphate could eliminate the inhibition. The solubilized enzyme was partially purified by ammonium sulphate fractionation and Sephadex G‐150 chromatography. A tetrahydropteridine and ferrous ion were required as cofactors for the partially purified enzyme. Among various divalent cations, only ferrous ion could activate the partially purified enzyme. The enzyme was inhibited by L‐α‐methyl‐p‐tyrosine and catecholamines such as dopamine. The optimum pH was found between 5.5 and 6.0. Km values toward tyrosine, 2‐amino‐4‐hydroxy‐6,7‐dimethyltetrahydropteridine and Fe2+, were approximately 5 × 10−5 M, 1 × 10−4 M and 4 × 10−4 M, respectively.