bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of c axis pole figures and grain size during dynamic recrystallization: Results from experimentally sheared quartzite
Authors: Heilbronner Renée , Tullis Jan
Published: October 2006

Quartzite samples experimentally sheared at conditions where subgrain rotation and grain boundary migration recrystallization are active show a striking change in the c axis crystallographic preferred orientation (CPO) with increasing shear strain (up to γ = 8) and degree of recrystallization (up to 100%). We used optical methods to determine the c axis CPO for the bulk samples and for porphyroclasts and recrystallized grains separately and to track the strengths of the CPOs in five different orientation domains with increasing γ. The c axis pole figure evolves from a broad peripheral maximum indicative of basal 〈a〉 slip, to an inclined single girdle with two maxima indicative of rhomb 〈a〉 slip, and finally an elongate single maximum at the girdle center indicative of prism 〈a〉 slip; throughout this sequence the fabric skeleton rotates with the sense of shear. The bulk preferred c axis orientation results from growth and shrinkage of differently oriented crystallographic domains. Grain boundary density analysis indicates that the size of prism 〈a〉 recrystallized grains is 1.5 times that of average and 2 times that of rhomb grains, indicating that prism 〈a〉 slip is significantly easier at our experimental conditions. This inference is supported by autocorrelation function analysis of the various orientation domains and how they evolve with strain. Similar progressive changes in c axis CPO are observed in quartzites naturally sheared at conditions where grain boundary migration recrystallization operates. These results indicate that achievement of microstructural and mechanical steady state requires high strain and complete recrystallization.
Sr/Ca and δ18O in a fast‐growing Diploria strigosa coral: Evaluation of a new climate archive for the tropical Atlantic
Authors: Hetzinger Steffen , Pfeiffer Miriam , Dullo Wolf‐Christian , Ruprecht Eberhard , Garbe‐Schönberg Dieter
Published: October 2006

This study provides the first monthly resolved, 41‐year record of geochemical variations (δ18O and Sr/Ca) in a fast‐growing Diploria strigosa brain coral from Guadeloupe, Caribbean Sea. Linear regression yields a significant correlation of coral Sr/Ca (δ18O) with instrumental sea surface temperature (SST) on both monthly and mean annual scales (e.g., r = −0.59 for correlation between Simple Ocean Data Assimilation (SODA) SST and Sr/Ca, and r = −0.66 for δ18O; mean annual scale, p < 0.0001). The generated coral Sr/Ca (δ18O)‐SST calibration equations are consistent with each other and with published equations using other coral species from different regions. Moreover, a high correlation of coral Sr/Ca and δ18O with local air temperature on a mean annual scale (r = −0.78 for Sr/Ca; r = −0.73 for δ18O; p < 0.0001) demonstrates the applicability of geochemical proxies measured from Diploria strigosa corals as reliable recorders for interannual temperature variability. Both coral proxies are highly correlated with annual and seasonal mean time series of major SST indices in the northern tropical Atlantic (e.g., r = −0.71 for correlation between the index of North Tropical Atlantic SST anomaly and Sr/Ca, and r = −0.70 for δ18O; mean annual scale, p < 0.001). Furthermore, the coral proxies capture the impact of the El Niño–Southern Oscillation on the northern tropical Atlantic during boreal spring. Thus fast‐growing Diploria strigosa corals are a promising new archive for the Atlantic Ocean.
Plasmon enhanced electron drag and terahertz photoconductance in a grating-gated field-effect transistor with two-dimensional electron channel
Authors: Aizin G. R. , Popov V. V. , Polischuk O. V.
Published: October 2006

The authors present a theory of dc photoresponse in two-dimensional (2D) electron channel in the grating-gated field-effect transistor irradiated by an electromagnetic wave of terahertz frequency. The authors determine photoinduced dc correction to the source-drain voltage and demonstrate that it has resonant peaks when the frequency of an external radiation coincides with 2D plasmon frequencies. The photoresponse is shown to depend on the asymmetric electron drag in the 2D channel with constant bias current. The amplitude of the resonant peaks has nonmonotonic temperature dependence with a maximum at elevated temperatures. The results explain qualitatively some important features of the photoresponse observed in recent experiments.
Relationships between changes in mechanical properties of the skin, wrinkling, and destruction of dermal collagen fiber bundles caused by photoaging
Authors: Oba Ai , Edwards Chris
Published: October 2006

Background/purpose: Long‐term exposure to ultraviolet (UV) radiation induces various cutaneous changes that differ from those because of physiological aging, including structural destruction of dermal collagen fiber bundles (DCFBs), which comprise the major component of the dermis. Wrinkling, a representative change in skin surface associated with photoaging, is often seen at the corners of the eyes and in the space between the eyebrows. These are locations where the skin contracts repeatedly and routinely. Lowered resiliency to skin contraction induced by marked structural changes in DCFBs may represent one cause of photo‐induced wrinkles. Using animal models of photoaging, changes in mechanical properties of the skin caused by UV irradiation were measured, and relationships between UV‐induced changes were analyzed.

Methods: Animal models of photoaging were prepared by irradiating hairless mice with UVB light. Dorsal skin surface replicas of animals were taken using silicon rubber, and volume of wrinkles was calculated using an image analyzer. Stress of the skin against horizontal contraction was measured using a new device called the Resiliometer. Three‐dimensional organization of dermal collagen structures in skin samples collected from the back of each animal was observed under scanning electron microscopy, and compactness of DCFBs was assessed from electron micrography.

Results: With time and therefore increasing UV dose, deep wrinkles formed on the backs of mice. Volume of wrinkles peaked at 8 weeks. All parameters obtained from Resiliometer measurements were increased by irradiation. DCFB structure was degraded in a radiation dose‐dependent manner. DCFB grading was significantly correlated with each Resiliometer parameter. Significant correlations were also observed between each Resiliometer parameter and volume of wrinkles.

Conclusion: Stress of the skin against horizontal contraction obtained using the Resiliometer changes following UV irradiation, correlating with photo‐induced wrinkling and destruction of DCFBs. These results support the hypothesis that changed force of restitution to skin contraction induced by marked structural changes in DCFBs represents one cause of photo‐induced wrinkles. The resiliometric parameter may offer a good indicator for monitoring the condition of DCFB structure, as changes in these would induce failure in restitution to skin contraction, leading to wrinkling.
An eIF4E allele confers resistance to an uncapped and non‐polyadenylated RNA virus in melon
Authors: Nieto Cristina , Morales Monica , Orjeda Gisella , Clepet Christian , Monfort Amparo , Sturbois Benedicte , Puigdomènech Pere , Pitrat Michel , Caboche Michel , Dogimont Catherine , Garcia‐Mas Jordi , Aranda Miguel. A. , Bendahmane Abdelhafid
Published: October 2006

The characterization of natural recessive resistance genes and virus‐resistant mutants of Arabidopsis have implicated translation initiation factors of the 4E family [eIF4E and eIF(iso)4E] as susceptibility factors required for virus multiplication and resistance expression. To date, viruses controlled by these genes mainly belong to the family Potyviridae. Melon necrotic spot virus (MNSV) belongs to the family Tombusviridae (genus Carmovirus) and is an uncapped and non‐polyadenylated RNA virus. In melon, nsv‐mediated resistance is a natural source of recessive resistance against all strains of MNSV except MNSV‐264. Analyses of chimeras between non‐resistance‐breaking and resistance‐breaking strains have shown that the avirulence determinant maps to the 3′‐untranslated region (3′‐UTR) of the viral genome. Using a combination of positional cloning and microsynteny analysis between Arabidopsis thaliana and melon, we genetically and physically delimited the nsv locus to a single bacterial artificial chromosome clone and identified the melon eukaryotic translation initiation factor 4E (Cm‐eIF4E) as a candidate gene. Complementation analysis using a biolistic transient expression assay, confirmed Cm‐eIF4E as the product of nsv. A single amino acid change at position 228 of the protein led to the resistance to MNSV. Protein expression and cap‐binding analysis showed that Cm‐eIF4E encoded by a resistant plant was not affected in it's cap‐binding activity. The Agrobacterium‐mediated transient expression of the susceptibility allele of Cm‐eIF4E in Nicotiana benthamiana enhanced MNSV‐264 accumulation. Based on these results, a model to explain melon resistance to MNSV is proposed. These data, and data from other authors, suggest that translation initiation factors of the eIF4E family are universal determinants of plant susceptibility to RNA viruses.
PROVOCATION OF CEREBRAL SEIZURES BY DERANGEMENT OF THE NATURAL BALANCE BETWEEN GLUTAMIC ACID AND γ‐AMINOBUTYRIC ACID
Authors: Wiechert P. , Herbst A.
Published: October 2006

After intracisternal injection of glutamic acid and pyridoxal 5‐phosphate, cerebral seizures could be evoked in dogs. With a small dose, these seizures were limited predominantly to the facial area. An interruption or prevention of the seizures was possible by intracistemal injection of γ‐aininobutyric acid or by pretreatment of the animals with α‐methyl‐α‐ethyl‐succinimide. The correspondence of clinical symptoms and therapeutic effect suggests a relation between these experimentally‐induced seizures and temporal lobe epilepsy in man.
THE EFFECT OF AN ECTOSYLVIAN EPILEPTOGENIC FOCUS INDUCED BY TOPICAL APPLICATION OF MESCALINE ON NITROGENOUS COMPOUNDS IN THE NEOCORTEX OF CAT
Authors: Badiu G. , Mison‐Crighel Nella
Published: October 2006

An cctosylvian spiking focus, induced by topical application of mescaline, brought about changes in nitrogenous compounds not only in the focus but throughout the cerebral cortex.

Prior to the onset of the spiking focus, 2 min after mescaline application, ammonia levels increased significantly in all neocortical areas, especially at the focus and homolateral marginal gyrus; free amide nitrogen decreased and non‐protein nitrogen increased throughout the cortex.

During the development of the focus–at 30 min–the ammonia level still remained high, with a tendency to decrease, and free amide nitrogen was decreased in all neocortical areas.

A decrease in‘protein nitrogen’in marginal gyri, on either side and in lipid nitrogen in the epileptical focus as well as in both marginal gyri was also noted.
THE INFLUENCE OF BILIRUBIN ON OXIDATIVE PHOSPHORYLATION AND RELATED REACTIONS IN BRAIN AND LIVER MITOCHONDRIA: EFFECTS OF PROTEIN‐BINDING
Authors: Menken Matthew , Waggoner Jeanne G. , Berlin Nathaniel I.
Published: October 2006

1. The uncoupling of oxidative phosphorylation of liver mitochondria by bilirubin does not occur in the presence of equimolar quantities of human serum albumin. With brain mitochondria, however, albumin was not protective.

2. A similar protective effect of albumin for liver, but not for brain, mitochondria was observed in studies of the effects of bilirubin on the 32Pi‐ATP exchange reaction.

3. The latent ATPase of fresh brain mitochondria is activated by Mg2+ but only slightly by DNP. Bilirubin increased the Mg2+ stimulated ATPase activity in liver mitochondria but depressed this activity in brain mitochondria. These effects were uninfluenced by protein binding.

4. Isotope studies with [14C]bilirubin demonstrated that the affinity of brain mitochondria for albumin‐bound bilirubin is not greater than that of liver mitochondria.

5. The greater toxicity of protein‐bound bilirubin for brain mitochondria than for liver mitochondria might be related to the greater lipid content of brain mitochondria.
GLYCOLYSIS IN RAT BRAIN TISSUE SLICES FOLLOWING NEONATAL HEAD X‐IRRADIATION: RELATION OF REGIONAL DIFFERENCES TO THE LDH: GPDH RATIO1
Authors: de Vellis Jean
Published: October 2006

—Following head X‐irradiation (750 r) of 2‐day‐old rats the aerobic formation of lactate in the presence or absence of chloral was markedly increased in medulla slices but remained unchanged in cerebral cortex and brain stem slices. The ratio of lactate dehydrogenase (EC 1.1.1.27) to glycerolphosphate dehydrogenase (EC 1.1.1.8) was slightly increased in cortex and brain stem but more than doubled in medulla. The relation of the increased aerobic formation of lactate in irradiated medulla to the lactate dehydrogenase:glycerolphosphate dehydrogenase ratio is discussed.
QUANTITATIVE AND QUALITATIVE CHANGES IN RIBONUCLEIC ACIDS OF RAT BRAIN DEPENDENT ON AGE AND TRAINING EXPERIMENTS
Authors: Dellweg H. , Gerner R. , Wacker A.
Published: October 2006

—Investigations of rat brain RNA were carried out by phenol extraction of the whole brain and chromatographic fractionation into ribosomal RNA and transfer RNA.

(1) The amounts of both RNA species increase in the course of the animal's development reaching a maximum at about the tenth week of life. The ratio of both species remains constant throughout the growth to the twentieth week. After the rats had been trained how to reach their forage by balancing on a stressed rope, the rRNA content was found to be significantly higher, whereas the tRNA content was unchanged.

(2) The portion of ribosomes bound in polysome complexes decreases with increasing age of rats. Conditioning of the animals brings about again an increase in polysome content. It is supposed that this reflects an enhanced synthesis of specific proteins in young developing rats and in the course of conditioning.

(3) In young rats a second valine specific tRNA could be found as a minor component in addition to the major valyl‐tRNA. This additional component disappears as the animals advance to an age of 3 weeks and it could not be detected in the brains of rats after training experiments. In tRNAs specific for the amino acids leucine, lysine and phenylalanine no kind of deviation could be stated.
THE EFFECT OF HYPOXIA ON BRAIN γ‐AMINOBUTYRIC ACID LEVELS1
Authors: Wood J. D. , Watson W. J. , Ducker A. J.
Published: October 2006

Abstract—

(1) Animals were exposed to hypoxic environments either by supplying them with breathing mixtures low in oxygen or by exposing them in a decompression chamber to simulated altitude. Both methods of producing hypoxia brought about significant increases in brain GABA levels.

(2) Elevated GABA levels occurred in all species tested (mouse, hamster, rat, guinea pig, and rabbit) and reached maximal concentration 60 min after the initiation of breathing the hypoxic mixtures. Extension of the exposure beyond 60 min brought about a gradual decline in GABA level from the maximal value reached.

(3) A linear relation was found between the oxygen content of the gas mixture and the elevation of GABA level. For guinea pigs, at least, the critical oxygen content required to prevent elevation of GABA level was 8.1 per cent.
AMINO ACID TRANSPORT BY CHOROID PLEXUS IN VITRO1
Authors: Lorenzo A. V. , Cutler R. W. P.
Published: October 2006

Abstract—

Choroid plexus from mongrel cats was incubated from 1 to 120 min in artificial cerebrospinal fluid containing α‐amino[1‐14C]isobutyric acid. The uptake of α‐amino [1‐14C]isobutyric acid occurred against a concentration gradient, was saturable, dependent on metabolic energy, and inhibited by natural amino acids. These results indicate that a transport mechanism is present in choroid plexus which could serve to regulate amino acid concentration in the cerebrospinal fluid of animals.
THE EFFECT OF NERVE GROWTH FACTOR (NGF) ON THE SYNTHESIS OF GANGLIOSIDES 1
Authors: Graves M. , Varon S. , McKhann G.
Published: October 2006

—Dorsal root ganglia from 8‐day‐ and 14‐day‐old chick embryos contained gangliosides with a pattern qualitatively similar to that of embryonic chick brain. The pattern of gangliosides from dorsal root ganglia changed with age, there being a decrease in polysialogangliosides with increasing age. When isolated, dorsal root ganglia were incubated in the presence of a concentration of nerve growth factor (NGF) sufficient to promote the outgrowth of nerve fibres, there was increased incorporation of d‐[1‐14C]glucosamine into gangliosides. There was, however, no difference in the pattern of incorporation into gangliosides by control ganglia and those exposed to NGF.
CREATINE KINASE FROM BRAIN: KINETIC ASPECTS
Authors: Dawson D. M
Published: October 2006

Abstract— Creatine kinase derived from rabbit brain has been re‐examined with respect to its kinetic features. The enzyme from brain has lower Michaelis constants for both ADP and creatine phosphate than does the enzyme from rabbit muscle. Substrate inhibition by excess creatine phosphate occurs at a concentration approximating that found in the tissue. The enzyme from muscle is less sensitive to substrate inhibition.

The crude mitochondrial fraction from rat brain was centrifuged in a sucrose density gradient and the distribution of enzymatic activities among the subfractions was determined. The distribution of creatine kinase resembled that of two glycolytic enzymes; no evidence for a mitochondrial localization was found.
CONTENT OF ATP IN CULTIVATED NEURONS AND ASTROCYTES EXPOSED TO BALANCED AND POTASSIUM‐RICH MEDIA
Authors: Schousboe A , Booher J , Hertz L
Published: October 2006

Abstract— The content of ATP was measured in neurons from dorsal root ganglia and in cortical and spinal astrocytes with the luciferase method. No ATP could be demonstrated in the cortical cells but in the dorsal root neurons and spinal astrocytes an average amount of 7·9 and 11·9 × 10−15 mol per cell respectively was found. An increase in the external potassium concentration had no effect on the content of ATP in neurons (7·1 × 10−15 mol/cell) but led to a significant (P < 0·005) decline to 6·4 × 10−15 mol per cell in the astrocytes.
ON THE TURNOVER OF ACETYLCHOLINE IN NERVE ENDINGS OF MOUSE BRAIN IN VIVO
Authors: Schuberth J , Sparf B , Sundwall A
Published: October 2006

Abstract— Acetylcholine is synthesized and stored in the nerve endings from which the liberation of the nerve transmittor is regulated by the nerve activity. The aim of the present investigation was to measure the in vivo turnover of acetylcholine in this subcellular acetylcholine pool. This has been carried out by injecting labelled choline intravenously and then by measuring at different time intervals the ratio between labelled choline and acetylcholine in the fractions obtained after subcellular fractionation. It was found that the ratio radioactive choline to radioactive acetylcholine was the same (2:1) in whole brain and in the nerve ending fraction 2 to 20 min after injection. Since it was assumed that the same ratio is true also for the endogenous compounds the choline pool in the nerve terminals was considered to make up 13 nmoles/g brain. The results also indicate that plasma choline is rapidly equilibrated with the nerve terminals and transformed to acetylcholine at a rate of about 5 nmoles/g brain/min.
THE FREE AMINO ACIDS IN HUMAN CEREBROSPINAL FLUID
Authors: van Sande M. , Mardens Y. , Adriaenssens K. , Lowenthal A.
Published: October 2006

—(a) The free amino acids in human cerebrospinal fluid from 78 subjects have been determined by means of ion exchange chromatography. Analyses were performed on 2 to 3 ml of CSF.

(b) Normal values are given for a control group of 13 subjects.

(c) The presence of homocarnosine in human CSF is ascertained. The concentration of this dipeptide is very high in CSF samples from phenylketonuric patients.

(d) The CSF amino acid pattern in 20 patients with a metabolic disease is discussed.

(e) The CSF amino acid pattern of 38 patients suffering from a variety of neurological conditions are reported.
Depletion of biotin from brain and liver in biotin deficiency
Authors: Bhagavan H. N. , Coursin D. B.
Published: October 2006

The effects of biotin deficiency on the metabolism of glucose (Bhagavan, Coursin and Dakshinamurti, 1965; Bhagavan, Maruyama and Coursin, 1967; Bhagavan, Coursin and Stewart, 1969) and central nervous system function (Bhagavan, Stewart, Dakshinamurti and Coursin, 1966; Stewart, Bhagavan, Coursin and Dakshinamurti, 1966; Stewart, Bhagavan and Coursin, 1967a, b; 1968) have already been reported. In a study of the biochemical changes in the brain and other tissues of the rat in biotin deficiency, the depletion of biotin from the brain and liver during the course of the deficiency has been followed. We found that while the liver lost over 90 per cent of its biotin, the depletion from the brain was only about 50 per cent after 8 weeks on the deficient diet. These data comprise the present report.
SYNTHESIS OF RNA IN DEVELOPING RAT BRAIN IN VITRO
Authors: Sharma Shail K. , Singh U. N.
Published: October 2006

—Incorporation of [8‐14C]adenine into a rapidly‐labelled fraction of RNA derived from the nucleus, and into a cytoplasmic RNA of high molecular weight was studied in brain slices from new born rats. The kinetic behaviour of the two fractions of RNA was compatible with a precursor‐product relationship between them. The change in the specific activity of adenine and the reduction of radioactivity in prelabelled RNA of brain slices in the presence of actinomycin D, suggest that the observed degradation of nuclear RNA is not due to random changes, but is limited to a relatively small fraction, presumably messenger RNA.
ADENOSINETRIPHOSPHATASE AND NUCLEOTIDE METABOLISM IN SYNAPTOSOMES OF RAT BRAIN1
Authors: Abdel‐Latif Ata A. , Smith Jack P. , Hedrick Nina
Published: October 2006

—In the presence of synaptosomes prepared from rat brain, only ATP, dATP and ADP but not dADP were active as substrates of phosphatase (ATP phosphohydrolase; EC 3.6.1 4) in the presence of 150mm‐Na+ and 20mm‐K+. An active adenylate kinase (ATP:AMP phosphotransferase; EC 2.7.4.3.) was demonstrated in the synaptosomal fractions by means of paper chromatography, paper electrophoresis and enzymic reactions, so that the high activity with ADP as substrate could represent an activity of an ATPase. Apparently dADP was not a substrate for the kinase; no dATP was formed when dADP was incubated with the synaptosomal fraction in the presence of Na+, K+ and Mg2+. Small amounts of P1 were liberated with dADP, IDP, GDP or CDP, but not UDP, as substrates, but none was produced in the presence of mononucleotides. The adenine‐deoxyribose bond, but not the adenine‐ribose bond, was hydrolysed upon the addition of 5% (w/v) TCA to the reaction mixture.

The KM for the hydrolysis of ATP but not ITP, in the presence of Mg2+, or of Na+, K+ and Mg2+, was lower for the synaptosomal ATPase than for the microsomal ATPase, and the values for Vmax for synaptosomal ATPase were higher. The activation increment was generally higher for the synaptosomal ATPase and no distinct differences in the properties of the enzyme from either particulate fractions were observed. Mg2+ could be partially replaced by Mn2+ in the synaptosomal ATPase system, but there was little Na+‐K+‐activation observed in the presence of the latter. The effects of ouabain and of homogenization under various conditions suggested localization of the K+‐sensitive site of the ATPase on the surface of the synaptosomal membrane. Activity of the Na+‐K+‐Mg2+ ATPase increased after freezing and thawing of the sonicated, sucrose or tris‐treated preparations but decreased considerably in the synaptosomes treated with 001 m‐deoxycholate. Activity of the Mg2+ ATPase in the latter preparation showed little change.
Effects of dichloroisopropylarterenol on respiration, nucleotide ∼ P and phospholipids of slices of cerebral cortex
Authors: Morazain R.
Published: October 2006

In a Recent report Hokin (1969) showed that norepinephrine stimulated the incorporation of 32P into phosphatidic acid (PA) of slices of cerebral and cerebellar cortex and into phosphaditylinositol (PI) of slices of cerebral cortex. In the course of our experiments on agents affecting the metabolism of phospholipids, the effects of epinephrine and its antagonist, dichloroisopropylarterenol (DCI), on the labelling of energy‐rich nucleotides and phospholipids of cerebral tissue have been measured. Epinephrine had no significant effect but DCI stimulated the incorporation of 32P into PA by 165 per cent and into PI by 90 per cent.
LEVELS OF AMINO ACIDS AND PROTEINS IN PACINIAN CORPUSCLES OF THE CAT
Authors: Santini M. , Berl S.
Published: October 2006

Abstract— Paper chromatography of extracts from mesenteric Pacinian corpuscles of the cat revealed the presence of glutamic acid, glutamine, aspartic acid and alanine as major amino acids, and glycine, serine and threonine in traces; GABA was not detected. Levels of glutamic acid (0·75 μmol/g ′ 0·37, s.d.), glutamine (1·34 ± 0·55), and aspartic acid (0·32 ± 0·22) of mesenteric and pancreatic samples of Pacinian corpuscles were determined by separation on chromatographic columns. The protein values averaged 5·2 ± 0·66 per cant of the wet weight.

Treatment of the cats with reserpine or pargyline or deafferentation of the Pacinian corpuscles did not significantly alter these values.
TRYPTOPHAN TRANSPORT ACROSS THE SYNAPTOSOMAL MEMBRANE1
Authors: Grahame‐Smith D. G. , Parfitt A. G.
Published: October 2006

Abstract—

Crude mitochondrial fractions prepared from rat brains took up l‐tryptophan. The component of the crude mitochondrial fraction responsible for this uptake is the synaptosome. After uptake of tryptophan occurred, rupture of synaptosomes released 97 per cent of the tryptophan unchanged. Rupture of synaptosomes abolished uptake.

Penetration of the limiting membrane of synaptosomes by l‐tryptophan both as influx and efflux was studied. Uptake of l‐tryptophan was rapid, temperature dependent, partially inhibited by cyanide, 2‐deoxy‐d‐glucose and ouabain, but apparently unaffected by low external sodium ion concentrations. d‐tryptophan was a poor inhibiteur of l‐tryptophan uptake. Concentration gradients Internal: external of up to 4:1 were achieved. Kinetic studies on l‐tryptophan uptake and its competitive inhibition by l‐phenylalanine indicated a saturable carrier‐mediated transport system, present in the rat at birth.

l‐Tryptophan efflux from preloaded synaptosomes was markedly stimulated by certain arrino acids and its influx stimulated by preloading with l‐tryptophan. This countertransport is further evidence for carrier‐mediated or facilitated diffusion. On the basis of countertransport data there seem to be at least two systems for transporting amino acids across synaptosomal membrane.

The relevance of these studies to the role of l‐tryptophan as the initial precursor of brain 5‐hydroxytryptamine is examined.
THE ACTIVITY OF GANGLIOSIDE SIALIDASE IN THE DEVELOPING HUMAN BRAIN
Authors: ÖHman R. , Svennerholm L.
Published: October 2006

—The development of ganglioside sialidase and of four different p‐nitrophenyl glycosidases in human brain was investigated including both prenatal and postnatal periods. The developmental curve for sialidase was different from that of the other glycosidases. While p‐nitrophenyl glycosidases showed high activities at an early stage of development (21 foetal weeks), and remained at about the same level, ganglioside sialidase was not detected before the foetal age of 15‐20 weeks. The sialidase activity at term reached about half the adult level and there was a possible decrease in activity during the first year. The sialidase activity then increased, approaching the adult level at about the age of 5 years. The development of the ganglioside sialidase activity in human brain can be related to changes in the concentration of individual brain ganglioside components. The late maturation of the sialidase system in relation to other glycohydrolases is also discussed as a possible protective mechanism for sialic acid‐containing compounds during the early period of development.
INCORPORATION OF [14C]N‐ACETYL NEURAMINIC ACID INTO BRAIN GLYCOPROTEINS AND GANGLIOSIDES IN VIVO1
Authors: De Vries G. H. , Barondes S. H.
Published: October 2006

—Intracerebrally administered [14C]N‐acetyl neuraminic acid was incorporated into brain glycoproteins and gangliosides. Incorporation into both classes of compounds was markedly inhibited by acetoxycycloheximide but incorporation into the soluble glycoproteins of the nerve‐ending fraction was inhibited least of all. In contrast to glucosamine and fucose, a relatively small proportion of the injected [14C]NANA was incorporated.
CATECHOLAMINE METABOLISM IN THE DOG: COMPARISON OF INTRAVENOUSLY AND INTRAVENTRICULARLY ADMINISTERED [14C]DOPAMINE AND [3H]NOREPINEPHRINE
Authors: Chase T. N. , Breese G. R. , Gordon Edna K. , Kopin I. J.
Published: October 2006

—The urinary excretion of labelled metabolites was measured in dogs which had been injected intravenously or intraventricularly with [3H]norepinephrine or [14C]dopamine. [3H]Norepinephrine injected by either route produced more labelled 3‐methoxy‐4‐hydroxy‐phenylglycol than 3‐methoxy‐4‐hydroxymandelic acid, as did [14C]dopamine after intravenous administration. In contrast, following the intraventricular injection of [14C]dopamine, more [14C]3‐methoxy‐4‐hydroxymandelic acid was formed than [14C]3‐methoxy‐4‐hydroxyphenylglycol. These observations suggest that the metabolism of exogenously‐administered and endogenously‐formed norepinephrine may proceed through different routes and that the predominant metabolite of norepinephrine in canine brain may be 3‐methoxy‐4‐hydroxymandelic acid rather than 3‐methoxy‐4‐hydroxyphenylglycol.
ABSENCE OF DIRECT ACTION OF INSULIN ON METABOLISM OF THE ISOLATED PERFUSED RAT BRAIN1
Authors: Sloviter H. A. , Yamada H.
Published: October 2006

The ability of insulin to influence directly the metabolism of the mammalian brain has been evaluated with an isolated, perfused rat brain preparation. Insulin was added to the perfusion fluid or was injected into the rat from which the isolated brain preparation was subsequently made. The spontaneous electrical activity of the brain, the rate of cerebral glucose consumption and the rate of efflux of K+from the brain were not affected by insulin. We conclude that insulin either does not act directly on the brain or that its action is very small and/or very slow in comparison with its action on other tissues. We suggest that the effects on brain metabolism reported to occur after administering insulin and glucose to the intact animal may be secondary to the large stimulation of the metabolism of the liver and/or other organs.
ARYLSULPHATASES IN HUMAN BRAIN: ASSAY, SOME PROPERTIES, AND DISTRIBUTION1
Authors: Harinath B. C , Robins E
Published: October 2006

Abstract— Arylsulphatases (aryl‐sulphate sulphohydrolases; E.C. 3.1.6.1) in human brain were studied using a highly sensitive fluorometric technique based on the use of 4‐methyl‐umbelliferone sulphate (MUS) as substrate. In the dialysed homogenate of human brain at least two enzymes could be distinguished on the basis of pH optima and substrate concentration. One MUS‐sulphatase, of the ‘insoluble’ type, exhibited a pH optimum of 6–9 and an apparent Km of 0.05 mM, whereas the second, belonging to the ‘soluble’ type, exhibited pH optimum of 6–0 and an apparent Km of 6.25 mM. Pronounced activities of the two arylsulphatases were observed in the 18,000 g sediment. About 25 per cent of the total tissue activity of the ‘soluble’‐type MUS‐sulphatase was found in the soluble subcellular fraction. However, this enzyme was completely solubilized by extraction of acetone‐dried human brain with acetate buffer.
THE EFFECT OF MODERATE AND MARKED HYPERCAPNIA UPON THE ENERGY STATE AND UPON THE CYTOPLASMIC NADH/NAD+ RATIO OF THE RAT BRAIN
Authors: Eolbergrová Jaroslava , MacMillan V. , Siesjö B. K.
Published: October 2006

Abstract— The energy state of brain tissue was evaluated from the tissue concentrations of ATP, ADP and AMP and the cytoplasmic NADH/NAD+ ratio from the tissue, CSF and blood concentrations of lactate and pyruvate, and from the intracellular pH′, in rats exposed to carbon dioxide concentrations of 640 per cent. The hypercapnia had no significant effect on the energy state of the tissue. Hypercapnia of increasing severity gave rise to a progressive decrease in the pyruvate concentration; the lactate concentration fell at low CO2 concentrations, but no further decrease was observed at CO2 concentrations greater than 20 per cent. There was a progressive rise in the intracellular lactate/pyruvate ratio at increasing CO2 concentrations, corresponding to the fall in intracellular pH, i.e. the calculated NADH/NAD+ ratios remained normal. It is therefore concluded that hypercapnia does not affect the cytoplasmic redox state.
AN INVESTIGATION OF THE POSSIBLE ROLE OF PHOSPHOINOSITIDES AS REGULATORS OF ACTION POTENTIALS BY STUDYING THE EFFECT OF ELECTRICAL STIMULATION, TETRODOTOXIN AND CINCHOCAINE ON PHOSPHOINOSITIDE LABELLING BY 32P IN RABBIT VAGUS
Authors: Salway J. G. , Hughes I. E.
Published: October 2006

Abstract— The effect of electrical stimulation, tetrodotoxin and cinchocaine (the latter two substances abolish action potentials) on the incorporation of [32P]orthophosphate into the phosphoinositides of isolated rabbit vagus nerve has been studied. Electrical stimulation, or treatment with tetrodotoxin, had little significant effect on the incorporation of [32P]orthophosphate into the phosphoinositides. Cinchocaine, however, caused a 3.5–4.4‐fold increase (P= < 0.001) in monophosphoinositide labelling. These findings are discussed in view of the possible function of the phosphoinositides in the nervous system.
DETECTION, DETERMINATION, AND METABOLISM IN VITRO OF GANGLIOSIDES IN MAMMALIAN SYMPATHETIC GANGLIA1
Authors: Harris J. U. , Klingman J. D.
Published: October 2006

Abstract— Sympathetic ganglia of the rat and cat were examined for the occurrence and distribution of gangliosides. Each rat superior cervical ganglion contained 0.3 nmol of ganglioside‐sialic acid. Extracts of cat superior cervical and nodose ganglia were chromatographed on silica gel thin‐layer plates. The resulting patterns suggested that similar distributions of multiple forms of gangliosides occur in these two tissues, with the fast‐moving gangliosides predominating. The metabolic activity of gangliosides was also investigated in rat superior cervical ganglia in vitro. Evidence was obtained that 14C from [U‐14C]glucose, [U‐14C]pyruvate, and [U‐14C]glucosamine was incorporated into the gangliosides.
ENHANCED FRAGILITY OF NEURAL LYSOSOMES FROM CHICKS SUFFERING FROM GALACTOSE TOXICITY1
Authors: Blosser J. C. , Wells W. W.
Published: October 2006

—The stability of neural lysosomes to osmotic and temperature shock and the free (non‐sedimentable) activities of selected lysosomal hydrolases from chicks suffering from galactose neurotoxicity were investigated. The neural lysosomes from chicks fed galactose demonstrated enhanced fragility to both elevated temperature and hypo‐osmotic media in comparison to the behavior of neural lysosomes isolated from control animals. The increased lability to osmotic shock could be duplicated by preincubation of normal lysosomes in solutions of galactose or galactitol. Further, the increased fragility induced in vivo by galactose feeding could be reversed by removing the chicks from the diet for 8 h, and such removal was accompanied in the brain by large reductions in levels of galactose and galactitol. The free activities of both β‐galactosidase (EC 3.2.1.23) and β‐N‐acetyl hexosaminidase (EC 3.2.1.30) were elevated above those of controls, and the percentage increases were proportional to the combined brain levels of galactose and galactitol. Our data suggest that increased fragility of lysosomes is a function of the accumulation of galactose and galactitol in the brains of chicks fed toxic amounts of galactose. Alteration of lysosomal integrity represents an attractive role for galactitol, as well as galactose, in the causation of galactose neurotoxicity in chicks.
ENZYME HISTOCHEMISTRY OF THE RAT HYPOTHALAMUS DURING EARLY DEVELOPMENT
Authors: Robinson N.
Published: October 2006

—The distribution, localization and changes in intensity of enzymes in major metabolic pathways of brain metabolism during the first 16 days postnatal life of the rat anterior hypothalamus are reported. Thiamine pyrophosphatase, acid phosphatase and 5′‐nucleotidase showed rapid increases in activity between 0 and 5 days whilst AChE, Mg2+–ATPase and monoamine oxidase exhibited little or no activity before 3 days. Most enzymes showed a moderate intensity at 16 days in all nuclei whilst for some enzymes of phosphate metabolism the reaction was strong. The precocity of some enzymes particularly monoamine oxidase, lactate dehydrogenase and NADH2‐diaphorase seen in other regions at birth, was not apparent in hypothalamic nuclei. Comparisons are made with other regions of the brain and the findings discussed in relation to function.
EFFECT OF DEXAMETHASONE ON PHENYLETHANOLAMINE N‐METHYLTRANSFERASE IN CHROMAFFIN TISSUE OF THE NEONATAL RAT
Authors: Ciaranello R. D. , Jacobowitz D. , Axelrod J.
Published: October 2006

Abstract— Treatment of neonatal rats with dexamethasone resulted in the appearance of phenylethanolamine‐N‐methyltransferase (PNMT) and numerous small, intensely fluorescent (SIF) cells in abdominal paraganglia and in sympathetic paravertebral ganglia. These cells may be derived from a primitive stem cell precursor, but because of their unusual anatomical features, origin from ganglion cells cannot be altogether ruled out. Associated with the proliferation of the cells was a marked increase in the PNMT activity of the tissues. The PNMT response to the glucocorticoid was limited to the first few days of life, as was the SIF cell response. After discontinuance of dexamethasone, the enzyme activity fell very rapidly, while the number of cells declined at a slower rate.
Effect of hypoxia on tyrosine and tryptophan hydroxylation in unanaesthetized rat brain
Authors: Davis J. N. , Carlsson A.
Published: October 2006

The Tyrosine and tryptophan hydroxylase enzymes have been proposed as rate‐limiting steps in the biosynthesis of catecholamines and 5‐hydroxytryptamine (5‐HT), respectively; thus under normal physiological conditions the rate of amine synthesis appears to be controlled by the activity of these hydroxylase enzymes (see Udenfriend, 1966; Lovenberg, Jequier and Sjoerdsma, 1968). Subtle changes in neuronal activity may result not in changes in the levels of the amine neurotransmitters, but rather in alteration in their production and metabolism without measurable change in their levels. Previous studies of the effect of hypoxia on monoamines have dealt with amine levels, but there have been no studies of the effect of lowered oxygen on the synthesis of these substances.
ENDOGENOUS MICROSOMAL PHOSPHOLIPID PEROXIDATION IN MOUSE BRAIN
Authors: Konat G.
Published: October 2006

Abstract— Release of malondialdehyde from microsomal phospholipids during incubation in vitro was studied in the brain cytoplasm and in the microsomes fortified by deproteinized cytosole.

Linearity between the log of specific activity of peroxidation (malondialdehyde release) and the negative log of protein concentration was demonstrated. The boiling of microsomes significantly quenched the ability to produce malondialdehyde, while preincubation with phospholipase A completely abolished this ability.

In general, aromatic and not aliphatic compounds inhibited the reaction. 1,1,1‐Trichloro‐2,2‐bis (p‐chlorophenyl) ethane (DDT) was found to be a selective inhibitor of membrane peroxidative activity. The maximal inhibition is invariable. The data obtained revealed that brain and liver microsomal phospholipid peroxidation differ in some respects and the differences are of both quantitative and qualitative nature.
SYNTHESIS OF ACETYLCHOLINE IN DIFFERENT COMPARTMENTS OF BRAIN NERVE TERMINALS IN VIVO AS STUDIED BY THE INCORPORATION OF CHOLINE FROM PLASMA AND THE EFFECT OF PENTOBARBITAL ON THIS PROCESS
Authors: Aquilonius S.‐M. , Flentge F. , Schuberth J. , Sparf B. , Sundwall A.
Published: October 2006

The time course of the incorporation of choline from plasma into a high and a low molecular weight fraction from mouse brain synaptosomes was studied. The fractions were obtained from lysed synaptosomes by gel filtration on Sephadex G‐25. An extremely rapid incorporation of radioactivity into acetylcholine was found in both fractions and in the time interval 0.25‐9 min after the intravenous administration of labelled choline, higher specific radioactivities of acetylcholine were found in the high molecular weight fraction than in the low molecular weight fraction. However, the specific radioactivity of choline in the high molecular weight fraction was much lower than that of acetylcholine. It was found that barbiturate anaesthesia caused a marked decrease in the labelling of acetylcholine in the high molecular weight fraction while the incorporation into the low molecular weight fraction was affected to a much smaller extent.

Acetylcholine of the high molecular weight fraction showed properties similar to those of vesicle‐bound acetylcholine.

The recoveries of labelled and endogenous acetylcholine and choline from the brain homogenates were calculated in different steps of the fractionation procedure. In the fraction containing lysed synaptosomes the recovery of radioactive acetylcholine was lower than that of endogenous acetylcholine. This may indicate the presence of two types of bound acetylcholine in the synaptosomes.

Different models for the intraneuronal synthesis of acetylcholine are discussed and it is proposed that a site of acetylcholine synthesis in vivo may be closely associated with some constituent of the high molecular weight fraction and directly coupled with the storage of the transmitter.
DEVELOPMENT OF THE BLOOD‐BRAIN BARRIER FOR 6‐HYDROXYDOPAMINE
Authors: Sachs Charlotte
Published: October 2006

The postnatal development of the blood‐brain barrier for the neurotoxic action of 6‐hydroxydopamine on central noradrenaline neurons has been investigated by recording the in vitro uptake of [3H]noradrenaline in slices from cerebral cortex, hypothalamus and spinal cord in rats treated with large doses of 6‐hydroxydopamine at different ages. The [3H]noradranaline uptake was permanently and markedly reduced in all regions when the animals were treated at birth, certainly related to degeneration of noradrenaline neurons, caused by 6‐OH‐DA. In the cerebral cortex and hypothalamus an efficient protection against the effects of 6‐OH‐DA on [3H]noradrenaline uptake developed postnatally, while in the spinal cord this protection was never seen to become complete. The results obtained indicate a rapid formation of a blood‐brain barrier for 6‐OH‐DA in the cerebral cortex between the 7th and 9th day after birth. In the hypothalamus the development of this barrier seemed to have a more gradual time‐course, but appeared to be fully developed already at day 5 postnatally. Also in the spinal cord the barrier developed more gradually from birth to the adult age. It was observed, however, that both in the cerebral cortex and in the spinal cord, the blood‐brain barrier developed, could not completely protect the central noradrenaline neurons from the neurotoxic actions of large doses of 6‐OH‐DA administered systemically to adult rats. Furthermore, the results obtained support the view that 6‐OH‐DA does not seem to apparently affect the outgrowth of remaining NA neurons which have not been destroyed by the 6‐OH‐DA treatment.
AMINO ACIDS IN SYNAPTIC VESICLES FROM MAMMALIAN CEREBRAL CORTEX: A REAPPRAISAL
Authors: De Belleroche J. S. , Bradford H. F.
Published: October 2006

Synaptic vesicles were prepared from rat cerebral cortex and separated by gel filtration from small molecular weight compounds contaminating this fraction. Electron microscopy of the vesicle suspension showed that vesicles were by far the most abundant morphological entities. The amino acid content of the purified vesicle fraction was examined and the two amino acids appearing in the most significant amounts were found to be taurine and glutamate. This amino acid pool was not osmotically sensitive as is the vesicular pool of ACh and remained attached to the vesicular protein after passage through Sephadex columns equilibrated in water. However, amino acids added to the vesicle fraction prior to passage through Sephadex did not become associated with this pool and this indicated that the vesicular pool was not likely to be an artifact due to the vesicular protein non‐specifically adsorbing amino acids. The release of taurine from incubated synaptosome beds was studied and elevated medium K+ (56 mm) was found to cause a small increase (36 per cent) in the amount of the taurine released to the medium. During the same experiments another physiologically active amino acid, glutamate, was released in more significant amounts, increasing in the medium by 186 per cent. The possible significance of the presence of taurine is discussed.
HIGH AFFINITY TRANSPORT OF CHOLINE INTO SYNAPTOSOMES OF RAT BRAIN1
Authors: Yamamura H. I. , Snyder S. H.
Published: October 2006

—The accumulation of [3H]choline into synaptosome‐enriched homogenates of rat corpus striatum, cerebral cortex and cerebellum was studied at [3H]choline concentrations varying from 0.5 to 100 μm. The accumulation of [3H]choline in these brain regions was saturable. Kinetic analysis of the accumulation of the radiolabel was performed by double‐reciprocal plots and by least squares iterative fitting of a substrate‐velocity curve to the data. With both of these techniques, the data were best satisfied by two transport components, a high affinity uptake system with Km. values of 1.4 μM (corpus striatum), and 3.1 μM (ceμ(cerebral cortex) and a low affinity uptake system with respective Km. values of 93 and 33 μM for these two brain regions. In the cerebellum choline was accumulated only by the low affinity system. When striatal homogenates were fractionated further into synaptosomes and mitochondria and incubated with varying concentrations of [3H]choline, the high affinity component of choline uptake was localized to the synaptosomal fraction. The high affinity uptake system required sodium, was sensitive to various metabolic inhibitors and was associated with considerable formation of [3H]acetylcholine. The low affinity uptake system was much less dependent on sodium, and was not associated with a marked degree of [3H]acetylcholine formation. Hemicholinium‐3 and acetylcholine were potent inhibitors of the high affinity uptake system. A variety of evidence suggests that the high affinity transport represents a selective accumulation of choline by cholinergic neurons, while the low affinity uptake system has some less specific function.