bluuebunny/crossref_metadata_2025 huggingface dataset:
Auditor Fees, Market Microstructure, and Firm Transparency
Authors: Danielsen Bartley R. , Van Ness Robert A. , Warr Richard S.
Published: September 2006

Abstract:  Auditors, as corporate insiders, have access to private information regarding the firm's financial and business opacity that is unavailable to outside investors. We test whether auditors price their knowledge of firm opacity in their audit fees by examining two competing hypotheses. The first states that higher audit fees may reflect the greater risk that the auditor faces in auditing an opaque firm. Under this hypothesis, market based measures of opacity will be positively correlated with higher fees. The second hypothesis states that firms buy reputational capital from their auditor by paying high fees in an attempt to improve the market's perception of the firm's transparency. In this case, higher audit fees are negatively correlated with market based measures of opacity. Our results are consistent with the first hypothesis, that auditors price opacity risk into their fees.
Comparison of bobuck (Trichosurus cunninghami) demography in two habitat types in the Strathbogie Ranges, Australia
Authors: Martin J. K. , Handasyde K. A.
Published: September 2006

The demographic characteristics of populations are determined by the life‐history strategies of their constituent individuals. Habitat characteristics, such as the availability of key resources, shape life‐history strategies; thus habitat variation may result in intraspecific variability in demography. We studied two neighbouring populations of bobucks or mountain brushtail possums Trichosurus cunninghami within a fragmented forest system. One population occurred in a forest patch that was selectively logged in the last 40 years; the other occupied narrow strips of linear roadside remnant vegetation that have not been logged for at least 100 years. Many demographic parameters of the two populations were similar, and were consistent with those described previously for a bobuck population living in continuous forest. For example, both sexes were long‐lived (at least 12 years), but there were fewer males in the oldest age classes at both sites. Most females produced one young per year and reproduction was highly seasonal. Females in the oldest age classes produced young, but none of these survived to pouch emergence. There were also marked differences between our two study populations: the sex ratio of adults was equal at the forest site but female‐biased (1.7:1) at the roadside site. Forest males weighed significantly less than males at the roadside site and females at both sites. The peak of births occurred more than a month later at the roadside than at the forest site. The sex ratio of roadside offspring did not differ significantly from parity; however, the sex ratio of young at the forest site was significantly male‐biased (62% of young). This demographic variation may be explained by differences in habitat characteristics (particularly logging history); a detailed investigation of resource availability at the two sites is warranted. Our results highlight the importance of studying multiple populations when attempting to describe the population ecology of a species.
Genetic diversity of captive binturongs (Arctictis binturong, Viverridae, Carnivora): implications for conservation
Authors: Cosson L. , Grassman L. L. , Zubaid A. , Vellayan S. , Tillier A. , Veron G.
Published: September 2006

The binturong Arctictis binturong is a threatened carnivore (Mammalia) that ranges throughout the forests of South‐east Asia. This study evaluates the genetic diversity of captive binturong populations in European zoos and attempts to assess their geographic origin. We sequenced the hypervariable region 1 of the mitochondrial control region of 56 binturongs, among which 20 had a known geographic origin. We showed that at least two distinct geographic clades exist and were able to assess the geographic clade to which captive individuals belong. Moreover, a low genetic diversity was observed among the captive population of European zoos. Although our results are preliminary, zoo managers should consider the evolutionary significant units identified by this study, and which correspond to recognized sub‐species, when planning binturong reproduction programs.
Morphology, echolocation and foraging behaviour in two sympatric sibling species of bat (Tylonycteris pachypus and Tylonycteris robustula) (Chiroptera: Vespertilionidae)
Authors: Zhang L. , Liang B. , Parsons S. , Wei L. , Zhang S.
Published: September 2006

We studied the wing morphology, echolocation calls, foraging behaviour and flight speed of Tylonycteris pachypus and Tylonycteris robustula in Longzhou County, South China during the summer (June–August) of 2005. The wingspan, wing loading and aspect ratio of the two species were relatively low, and those of T. pachypus were lower compared with T. robustula. The echolocation calls of T. pachypus and T. robustula consist of a broadband frequency modulated (FM) sweep followed by a short narrowband FM sweep. The dominant frequency of calls of T. pachypus was 65.1 kHz, whereas that of T. robustula was 57.7 kHz. The call frequencies (including highest frequency of the call, lowest frequency of the call and frequency of the call that contained most energy) of T. pachypus were higher than those of T. robustula, and the pulse duration of the former was longer than that of the latter. The inter‐pulse interval and bandwidth of the calls were not significantly different between the two species. Tylonycteris pachypus foraged in more complex environments than T. robustula, although the two species were both netted in edge habitats (around trees or houses), along pathways and in the tops of trees. Tylonycteris pachypus flew slower (straight level flight speed, 4.3 m s−1) than T. robustula (straight level flight speed, 4.8 m s−1). We discuss the relationship between wing morphology, echolocation calls, foraging behaviour and flight speed, and demonstrate resource partitioning between these two species in terms of morphological and behavioural factors.
Large‐scale seasonal variation in the prevalence and severity of chytridiomycosis
Authors: Kriger K. M. , Hero J.‐M.
Published: September 2006

The chytrid fungus Batrachochytrium dendrobatidis has been implicated as the causative agent of mass mortalities, population declines and the extinctions of amphibian species worldwide. Although several studies have shown that the prevalence of chytridiomycosis (the disease caused by the fungus) increases in cooler months, the magnitude and timing of these seasonal fluctuations have yet to be accurately quantified. We conducted disease sampling in a single population of stony creek frogs Litoria wilcoxii on 13 occasions over a 21‐month period and used quantitative real‐time polymerase chain reaction to detect and quantify the number of B. dendrobatidis zoospores present on samples. Disease prevalence varied significantly across sampling sessions, peaking at 58.3% (in early spring) and dropping to as low as 0% on two occasions (late summer and early autumn). There was a significant negative relationship between disease prevalence and mean air temperature in the 30 days prior to sampling. These large‐scale seasonal fluctuations in chytridiomycosis levels will strongly influence conservation programs and amphibian disease research.
THE CONCENTRATIONS OF FREE AMINO ACIDS AND OTHER ELECTROLYTES IN CEREBROSPINAL FLUID, IN VIVO DIALYSATE OF BRAIN, AND BLOOD PLASMA OF THE DOG*
Authors: BITO L. , Davson H. , Levin E. , Murray M. , Snider N.
Published: October 2006

The concentrations of free amino acids in plasma, CSF and in vivo dialysates of peripheral blood (neck sac fluid) and central nervous tissue (brain sac fluid) from each of five dogs (neck sac fluid from four of five dogs) were determined by ion‐exchange chromatography. Dialysates were obtained by implanting small dialysis sacs filled with a dextran‐saline solution into the subcutaneous tissue of the neck or the parenchyma of the brain at least 10 weeks before sample collection.

The mean plasma concentration of most amino acids was within the range of values reported in the literature for human or dog plasma. The concentrations of most amino acids were higher in the neck sac fluid than in plasma; this discrepancy, however, was, for the most part, small and could most likely be accounted for by falling plasma free amino acid levels prior to sample taking. Previous conclusions that the CSF concentrations of most amino acids are lower than plasma concentrations are confirmed, although the present work indicates that there may be considerable individual variation in the CSF/plasma distribution ratio with respect to most amino acids.

In the brain sac fluid the concentration of nearly every amino acid was consistently higher than that in CSF and lower than that in the neck sac fluid. The potassium concentration in the brain sac fluid was significantly higher than, and the total osmolality significantly lower than, those in the neck sac fluid. On the assumption that the brain sac fluid represents a dialysate of the brain extracellular fluid, these results contradict recent findings (Bito and Davson, 1965; 1966) indicating that the potassium concentration of the cortex extracellular fluid is lower than that of ventricular or cisterna magna CSF and certainly lower than that of plasma. Because of this and on the basis of consideration of the reaction of the brain to a foreign body, the possibility that the implanted brain sac lay on the‘blood side’of the bloodbrain barrier was suggested. Some implications of this possibility are discussed.
THE FREE AMINO ACIDS OF HUMAN SPINAL FLUID DETERMINED BY ION EXCHANGE CHROMATOGRAPHY
Authors: Dickinson Johanne C. , Hamilton Paul B.
Published: October 2006

(1) The free amino acids in human CSF from eighteen subjects have been determined. The analyses were performed on 0‐75 ml of CSF by an ion exchange chromatographic method which is capable of detection to the 10−10 mole level.

(2) The amino acids always found in readily detectable amounts were: taurine, threonine, serine, glutamine, glutamic acid, citrulline, glycine, alanine, α‐NH2‐n‐ butyric acid, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, ethanolamine, ornithine, lysine, histidine and arginine. Urea was present. Aspartic acid and cystine, though always present, occurred in small or trace amounts. Proline was found in four cases and tryptophan in thirteen cases. In addition, twelve unknown peaks were nearly always evident in every chromatogram.

(3) Filtrates 10 times more concentrated than those used regularly were prepared from pooled CSF and analysed. These analyses clearly confirmed the presence of those amino acids which were normally in very low concentration and they also served to distinguish the twelve unknown compounds from confusion with baseline artifacts.

(4) The distribution of free amino acids in CSF was different from their distribution in blood plasma.

(5) Despite a variety of neurological conditions and a wide age span few marked deviations were found in any of the amino acid concentrations.
HORMONAL CONTROL OF GLYCEROLPHOSPHATE DEHYDROGENASE IN THE RAT BRAIN1
Authors: de Vellis Jean , Inglish Diane
Published: October 2006

—Following hypophysectomy or adrenalectomy, glycerolphosphate dehydrogenase (GPDH) (EC 1.1.1.8) activity decreased exponentially in the cerebral hemispheres and brain stem of adult male rats. The latter region was more affected than the former. Malate dehydrogenase (EC 1.1.1.40), isocitrate dehydrogenase (EC 1.1.1.42), lactate dehydrogenase (EC 1.1.1.27) and mitochondrial glycerolphosphate dehydrogenase (EC 1.1.95.5) activities remained unchanged. Injection of adrenocorticotrophic hormone or cortisol in hypophysectomized rats or cortisol in adrenalectomized rats restored GPDH activity. Thyroidectomy and gonadectomy had no effect on GPDH activity. Liver GPDH was not decreased by hypophysectomy or adrenalectomy. Muscle GPDH was diminished slightly by adrenalectomy and as much as brain GPDH by hypophysectomy. In young rats GPDH developmental increase in activity was inhibited by hypophysectomy. These results clearly show that brain GPDH activity is specifically regulated by cortisol (and probably closely related corticosteroids).
CONTROL OF AEROBIC GLYCOLYSIS AND PYRUVATE KINASE ACTIVITY IN CEREBRAL CORTEX SLICES
Authors: Takagaki G.
Published: October 2006

Abstract— —The concentrations of glycolytic intermediates were measured in aerobically incubated guinea pig cerebral cortex slices. Increasing the concentration of potassium in the medium increased fructose diphosphate ten‐fold and triose phosphates three‐fold. Omitting calcium increased all the glycolytic intermediates except pyruvate; triose phosphates were increased most. The changed patterns of the glycolytic intermediate profile in the slices are consistent with the previously proposed hypothesis that the phosphofructokinase is a main regulatory step in glycolysis. Glycolysis is also limited at the step of pyruvate kinase, which is inhibited in cerebral cortex slices. Calcium in the tissue and cellular organization of the slices were shown to be responsible for this inhibition. It was concluded that the effects of potassium and calcium on aerobic glycolysis in cerebral cortex slices are direct—on the pyruvate kinase—and also indirect. Calcium was shown to be inhibitive also to the activities of hexokinase, phosphoglucoisomerase, phosphofructokinase, glyceraldehyde 3‐phosphate dehydrogenase and enolase of guinea pig cerebral tissue.
A TECHNIQUE FOR THE STUDY OF ACETYLCHOLINE TURNOVER IN MOUSE BRAIN IN VIVO
Authors: Schuberth J. , Sparf B. , Sundwall A.
Published: October 2006

Abstract— —A method to measure the rate of acetylcholine turnover in mouse brain in vivo has been developed. It is based on the formation of labelled acetylcholine from intravenously injected labelled choline. The isotopic dilution of choline in the brain has been measured by assaying endogenous choline in the brain by an enzymatic method using tritium‐labelled acetyl‐CoA and purified choline acetyltransferase.

The rate of acetylcholine turnover in the brain could be calculated at 50 n‐moles acetylcholine/g/min in conscious mice. In anaesthetized mice and in mice treated with oxotremorine, a decrease of acetylcholine turnover to about 10 n‐moles/g/min was found.
EFFECT OF γ‐AMINOBUTYRIC ACID ON BRAIN SEROTONIN AND CATECHOLAMINES
Authors: Yessaian N. H. , Armenian A. R. , Buniatian H. Ch.
Published: October 2006

—Intraperitoneal injections of GABA (5 mg/kg) to rats lowered the level of norepinephrine in brain, heart and spleen but not suprarenals and raised that of serotonin in brain. Changes of these monoamines were most pronounced in the hypothalamic region after 20min. A reduction of hypothalamic norepinephrine was also observed 15min following the intracarotid administration of 0·5 mg/kg of GABA. In these experiments there was a concomitant increase in the level of free GABA in the anterior portion of the ventral hypothalamus. Brain dopamine level and 5‐hydroxytryptophan decarboxylase, dihydroxyphenylalanine decarboxylase and monoamine oxidase activities were not affected. The 20 per cent increase of endogenous GABA observed in the midbrain 30 min following the administration of amino‐oxyacetic acid was accompanied by a sharp fall in norepinephrine level (39 per cent) and an increase in serotonin (20 per cent).

In in vitro studies 10–300 μg/ml of GABA were shown to release norepinephrine from cortical and hypothalamic slices, and to inhibit serotonin release without affecting 5‐hydroxytryptophan uptake and to have no effect on the release of dopamine from slices of the region of the corpus striatum nor on the activity of the enzymes mentioned.

Subcellular studies showed that the particulate:supernatant ratio for norepinephrine was reduced from a control value of 2·04 to 1·75 and that of serotonin was raised from 2·8 to 3·5. Following pretreatment with iproniazid, GABA reduced the raised level of brain norepinephrine to a greater extent than reserpine but not as intensively as amphetamine.

The results obtained suggest that these monoamines may be involved in the mechanisms underlying the action of GABA in brain and that the effect of GABA on brain monoamines may be of certain significance in synaptic events.
CHEMOSENSING: SELECTIVITY, SENSITIVITY AND ADDITIVE EFFECTS ON A STIMULANT‐INDUCED ACTIVITY OF OLFACTORY PREPARATIONS
Authors: Ash K. O. , Skogen J. D.
Published: October 2006

Abstract—

Stimulant‐induced changes in soluble preparations from rabbit olfactory epithelium were monitored by ultraviolet difference spectroscopy. A time‐dependent decrease of absorbance, maximum at 267 nm, was generated when specific stimulants were mixed with the olfactory preparations. Only seven of the 37 organic chemicals tested generated the absorbance change at 267 nm. The olfactory preparations exhibited a high degree of selectivity and sensitivity; measurable absorbance changes were observed when the active stimulant concentrations were 1 × 10−5m. The experimental results suggest a complex mechanism of conformational change for the initial stimulant‐induced molecular interactions in biological chemosensing.
PATTERN OF RNA SYNTHESIS IN RABBIT CORTEX DURING SLEEP
Authors: Vitale‐Neugebauer A. , Giuditta A. , Vitale B. , Giaquinto S.
Published: October 2006

Abstract—

The pattern of RNA biosynthesis in rabbit cerebral cortex was examined during periods of physiological sleep and wakefulness monitored with EEG techniques. The types of newly synthesized RNA were analysed by sedimentation on sucrose gradients. In experiments lasting 60 and 105 minutes the labelling ratio of RNA sedimenting in two regions of the gradient (28 S‐50 S50 S) increased with decreasing percentages of EEG synchronization. Analysis of the radioactivity distributions of five homogeneous experiments in terms of moments confirmed the dependence of the RNA synthetic pattern on the electric state of the cortex. The possible nature of the RNA species involved in this effect is discussed.
A STUDY OF THE NASCENT POLYPEPTIDES SYNTHESIZED ON THE FREE POLYRIBOSOMES OF RAT BRAIN IN VIVO1
Authors: Sellinger O. Z. , Ohlsson W. G. , Frankel A. J. , Azcurra J. M. , Petiet Patricia D.
Published: October 2006

The free polyribosomes of the cerebral cortex of the immature rat (12‐14 days old) were exposed to very low concentrations of trypsin at 0°C and for very brief periods of time and the conditions under which their breakdown to smaller aggregates occurs were determined. Trypsin also caused the release of nascent, radioactive polypeptides from polyribosomes prelabelled with [14C]amino acids in vivo. An examination of the kinetics of release of the nascent chains by trypsin revealed that it was dependent on the concentration of trypsin as well as on the duration of incubation in the presence of trypsin. The influence of the nature of the [14C]amino acid used as precursor of the nascent polypeptides and of the duration of the radioactive pulse in vivo was also determined. The radioactivity associated with polyribosomes as a result of the brief radioactive pulses administered (2 to 10 minutes) was incompletely removed even after the ribosomes were dissociated into subunits by EDTA. These findings suggest that the assembly of the cerebral ribosome in vivo must be a very rapid process, particularly in the immature animal.

The nature of the nascent, radioactive polypeptides was studied by disc gel and high voltage electrophoresis and by thin‐layer and column chromatography. Evidence was obtained that a rather limited number of qualitatively different molecules resides on the polyribosomes at any given moment.
DYNAMIC CHARACTERISTICS OF THE ‘FUNCTIONAL COMPARTMENT’ OF DOPAMINE IN DOPAMINERGIC TERMINALS OF THE RAT STRIATUM
Authors: Javoy F. , Glowinski J.
Published: October 2006

Rats were injected with α‐methyl‐p‐tyrosine and the disappearance of dopamine in the striatum was examined as a function of time. Two main phases of dopamine decline were detected which probably correspond to the amine utilization in a ‘functional’ and a ‘main storage compartment’ in dopaminergic terminals. Similar observations were made when the turnover of dopamine had been previously accelerated by thioproperazine. In control rats the half‐lives of dopamine were about 9 and 120 min in the ‘functional’ and ‘main storage’ compartments respectively. The rate of dopamine synthesis was estimated to be not less than 13‐2 μg/g/h and the rate of dopamine utilization in the ‘functional compartment’ was calculated to be about four times that of the ‘main storage compartment'.
EFFECTS OF INDUCED HYPOTHERMIA ON AMINO ACIDS AND GLYCOGEN IN RAT BRAIN1
Authors: Turinsky J , Mukherji B , Sloviter H. A
Published: October 2006

Abstract— The concentrations of free amino acids and glycogen in the cerebral cortex of normal and deeply hypothermic (body temperature 18–20°C) rats were measured. The significant changes which accompanied the induction of hypothermia were a large reduction in glutamic acid concentration and moderate increases in the concentrations of glutamine and aspartic acid. The concentrations of γ‐aminobutyric acid, N‐acetylaspartic acid and glycogen did not change significantly.
THE EFFECTS OF INTOXICATING DOSES OF ETHANOL UPON INTERMEDIARY METABOLISM IN RAT BRAIN
Authors: Veloso Dulce , Passonneau Janet V. , Veech R. L.
Published: October 2006

Abstract— The effect of acute (8‐min) and prolonged (13‐h) exposures to high doses of ethanol upon the intermediary metabolites of rat brain has been studied, with the use of a new freezing technique which minimizes post‐mortem changes. Injection of ethanol (80 mmol/kg body wt) produced general anaesthesia within 8 min after administration. At this time there were increases in the brain contents of glucose, glucose‐6‐phosphate and citrate; there was no change in arterial pCO2. Rats under ethanol anaesthesia for 13 h showed increases in brain contents of glycogen, glucose and glucose 6‐phosphate; and decreases in lactate, pyruvate, α‐oxoglutarate and malate. Under similar experimental conditions, arterial pCO2, increased from 37 to 51 Torr. The changes in levels of metabolites after injection of ethanol were similar to those after administration of many volatile anaesthetic agents or elevation of brain CO2 by other means. Although brain levels of malate and α‐oxoglutarate decreased after prolonged exposure to ethanol, the mitochondrial redox state was maintained. Accordingly, the levels of glutamate and aspartate fell in accordance with the law of mass action. The maintenance of the cytoplasmic and mitochondrial redox states in the brain during ethanol intoxication was in marked contrast to the effects on the liver. We suggest that the different effects observed in brain and liver result from the action of ethanol upon the nerve cell membrane in brain, whereas the primary target in liver is alcohol dehydrogenase.
SOME FACTORS INFLUENCING BRAIN GLYCOGEN IN THE NEONATE CHICK
Authors: Edwards C. , Rogers K. J.
Published: October 2006

—Studies of the brain glycogen concentration in the chick during the perinatal period showed that there was an increase immediately prior to hatching. This was followed by a pronounced decrease between 1 and 2 days after hatching. The decrease was most marked in the cerebellum. During ischaemia, the rate of glycogen depletion was greater in 1‐day‐old chicks than in 2‐ and 7‐day‐old birds. Brain glycogen concentration exhibited a circadian rhythm which was not closely related to changes in motor activity or body temperature. Exposure to a high environmental temperature (40°C) caused a depletion of glycogen, but exposure to a low temperature (2°C) had no effect. Four hours of hyperglycaemia resulted in a lowering of brain glycogen levels whereas hypoglycaemia was without effect.
THE EFFECTS OF TETRAPHENYLBORON ON THE ISOLATION OF NEURONAL AND GLIAL CELLS FROM GUINEA‐PIG BRAIN
Authors: Baritch J. A.
Published: October 2006

Abstract— The addition of 20 mM‐tetraphenylboron to the tissue‐softening medium of a neuronal and glial cell isolation procedure results in a 2‐fold and 5‐fold increase in the yield of neuronal and glial‐enriched material respectively. The purity of the isolated fractions appears unaltered. While tetraphenylboron strongly inhibits protein synthesis, carbonic anhydrase activity and structural integrity appear unaffected by tetraphenylboron. The potential use of this compound in cell isolations is discussed.
THE EFFECTS OF METOPIRONE AND ADRENALECTOMY ON THE REGULATION OF THE ENZYMES MONOAMINE OXIDASE AND CATECHOL‐O‐METHYL TRANSFERASE IN DIFFERENT BRAIN REGIONS
Authors: Parvez H. , Parvez S.
Published: October 2006

Abstract— The role of glucocorticoids in the regulation of the enzymes monoamine oxidase (MAO) and catechol‐O‐methyltransferase (COMT) in brain regions has been studied. Glucocorticoids were blocked by Metopirone. The activities of MAO and COMT were determined in the hypophysis, hypothalamus, pineal gland and in the rest of brain. All the cerebral tissues except the pineal gland demonstrated highest MAO activity 8 h after Metopirone administration, when glucocorticoids were at the lowest level. Prolonged treatment for 10 days significantly augmented MAO activity in brain, hypophysis and hypothalamus, and COMT in the hypophysis increased by 56 per cent. The COMT activity in the rest of the brain did not change significantly with either short or prolonged administration. Complete ablation of the adrenal cortex resulted in a 167 per cent rise in MAO activity of the hypophysis. Metopirone and hydrocortisone inhibit MAO and COMT in vitro. The results suggest that glucocorticoids in the circulation of normal animals inhibit the activities of MAO and COMT. The inhibition or ablation of these hormones removes this rate‐limiting control of catecholamine degradation resulting in higher activities of MAO and COMT. Metopirone, an inhibitor of MAO and COMT in vitro, acts in the opposite direction in vivo due to its inhibitory effects on corticoid biosynthesis.
THE EFFECT OF AGE, GROWTH RETARDATION AND ASPHYXIA ON ASCORBIC ACID CONCENTRATIONS IN DEVELOPING BRAIN
Authors: Adlard B. P. F. , de Souza S. W. , Moon Susan
Published: October 2006

Abstract— The concentration of ascorbic acid in whole rat brain during the first week of postnatal life was up to 100 per cent higher than in adult animals. A progressive fall in concentration occurred between 4 and 30 days of age. Corresponding changes did not occur in liver and adrenal gland, two other organs rich in ascorbic acid. Rats subjected to growth retardation during the fetal and suckling periods had, at 25 days of age, levels of ascorbic acid in the cerebellum and brainstem significantly higher than those of control animals. A period of prolonged asphyxia in 5‐day‐old rats resulted in a significant 4 per cent reduction in whole brain ascorbic acid concentration.
EARLY CHANGES IN RESPIRATION, AEROBIC GLYCOLYSIS AND CELLULAR NAD(P)H IN SLICES OF RAT CEREBRAL CORTEX EXPOSED TO ELEVATED CONCENTRATIONS OF POTASSIUM
Authors: Bull R. J. , Lutkenhoff S. D.
Published: October 2006

Abstract— The initial effects of an elevated potassium concentration (30 mm) on the energy metabolism of incubated slices of rat cerebral cortex have been examined using spectrophotometric and polarographic techniques. Respiratory responses to additions of potassium were found to be definitely limited in time. This response was followed by an increase in the rate of aerobic glycolysis. Slice NAD(P)H and cytochrome b paralleled this metabolic sequence by exhibiting an initial oxidation followed by a net increase in the steady‐state levels of reduced intermediates, particularly in the case of NAD(P)H. Substitution of pyruvate (10 mm) for glucose in the standard incubation media produced significant alterations in the respiratory responses to the addition of potassium. Although the period of increased oxygen consumption was again limited it was somewhat greater in magnitude and significantly prolonged in time relative to changes observed with glucose as substrate. Changes in steady‐state levels of NAD(P)H were altered similarly and the net increase of NAD(P)H was not observed with pyruvate as substrate. We suggest that the metabolic responses of brain slices to increased potassium do not involve simultaneous activation of the respiratory and glycolytic pathways as has been previously assumed. Rather, a distinctly biphasic response is observed reminiscent of the Crabtree effect observed in other systems.
THE RELEASE OF HISTAMINE FROM TISSUE SLICES OF RAT HYPOTHALAMUS1
Authors: Taylor K. M. , Snyder S. H.
Published: October 2006

Abstract— The efflux of endogenous histamine from small slices of rat hypothalamus has been studied. Histamine release was temperature dependent and could be increased 50 % after depolarization of the brain slices by 15 mm potassium. The presence of EDTA in the incubating media inhibited the release of histamine and blocked the effect of potassium. Theophylline and reserpine markedly increased release of histamine, whereas phenoxybenzamine inhibited release and blocked the effects of theophylline and reserpine. Efflux of histidine from hypothalamic tissue slices was not temperature‐dependent and was unaffected by the addition of potassium or any of the drugs studied.
BRAIN METABOLISM AT LOW TEMPERATURES
Authors: Heckers H. , Gercken G.
Published: October 2006

Abstract— Levels of ATP, ADP, phosphocreatine, glycogen, glucose, lactic acid and inorganic phosphate in the rabbit brain were determined after cerebral hypothermia to 24, 22, 20, 18 and 16°C brain temperature. Hypothermia was induced by isolated head perfusion by means of an extracorporeal device including a donor animal of the same species. In two experiments brains were cooled to 24 and 16°C, followed by rewarming to nearly normothermic values before brain biopsy was performed. In all experiments the electrical activity of the cerebral cortex was recorded intermittently.

No metabolic disturbances could be observed in 25 out of a total number of 26 experiments. Only one experiment showed a marked decrease in cerebral content of high‐energy phosphates, glycogen and glucose and a corresponding increase of lactic acid and inorganic phosphate. These metabolic changes were caused in our opinion by convulsive activity of the brain induced by hypothermia. This was recorded in an electrocorticogram at a brain temperature ranging from 18·9 to 17·8°C over a 150 s period, 5 min before this brain was removed from the animal. These findings demonstrate that hypothermia per se to 24–16°C under our experimental conditions does not cause damage to the rabbit brain, generally, but under special conditions can provoke an increase in energy requirement which exceeds the energy available.
EFFECTS OF SALT AND WATER LOADING ON CARBOHYDRATE AND ENERGY METABOLISM AND LEVELS OF SELECTED AMINO ACIDS IN THE BRAINS OF YOUNG MICE1
Authors: Thurston Jean Holowach , Hauhart R. E. , Jones Elizabeth M. , Ater JoAnn L.
Published: October 2006

—This is a report of the effect of extreme changes in plasma sodium concentration induced by chronic (5 d) water deprivation and hypertonic saline injections and acute (4 h) overhydration with hypotonic glucose or fructose on the water and electrolyte content and levels of selected metabolites in the brains of young mice. In the dehydrated hypernatremic mice (plasma Na+, 186 × 3 mequiv./1) significant increases were found in brain glucose (82%), alanine (16%), aspartate (45%), glutamate (19%), gamma‐amino butyrate (34%) and glutamine (42%) concentrations. In striking contrast, water‐intoxicated mice (plasma Na+, 110 × 4 mequiv./1) had significantly decreased levels of alanine (17%), aspartate (38%) and glutamate (33%). Significant reductions in brain lactate (30–40%) and malate concentrations (23%) in both groups of experimental mice are suggestive of reduced cerebral metabolic rate.

During adaptation to increased or decreased environmental salinity, levels of amino acids in amphibian brain increase or decrease, respectively, to maintain osmotic equilibrium and to limit the loss or gain of water in brain. The data show that a similar protective response can be evoked in mammalian brain.
CHOLINE ACETYLTRANSFERASE LEVELS IN DIENCEPHALIC NUCLEI OF THE RAT
Authors: Brownstein M. , Kobayashi R. , Palkovits M. , Saavedra J. M.
Published: October 2006

Abstract—

Choline acetyltransferase levels have been measured in specific nuclei of the diencephalon. On the whole, the thalamic nuclei contain higher concentrations of this enzyme than do the hypothalamic and preoptic nuclei. Those nuclei which seem to receive the most dense cholinergic innervation contain the highest levels of choline acetyltransferase.
EVIDENCE THAT 5‐METHOXY‐N, N‐DIMETHYL TRYPTAMINE IS A SPECIFIC SUBSTRATE FOR MAO‐A IN THE RAT: IMPLICATIONS FOR THE INDOLEAMINE DEPENDENT BEHAVIOURAL SYNDROME
Authors: Squires R. F.
Published: October 2006

Abstract—

A simple method for the separation of 5‐hydroxyindoleacetic acid (5‐HIAA) and 5‐methoxyindoleacetic acid (5‐MeOIAA) on columns of non‐ionic polystyrene (Amberlite XAD‐2) is described. Administration of 5‐methoxy‐N, N‐dimethyl‐tryptamine (5‐MeODMT) 2 mg/kg i. p. to rats results in a sixfold increase in brain 5‐MeOIAA within 15 min. This increase is blocked by the selective inhibitor of MAO‐A, clorgyline, but not by the selective inhibitor of MAO‐B, deprenyl, indicating that 5‐MeODMT is deaminated almost entirely by MAO‐A. The apparent 5‐MeOIAA concentration in the brains of L‐tryptophan loaded rats is not reduced by clorgyline and deprenyl, either singly or in combination, indicating that most of this fluorescence is due to other, unidentified substances. The apparent concentration of 5‐HIAA in rat brain, minus 5‐MeOIAA, is unaffected by deprenyl and reduced by clorgyline. However, clorgyline and deprenyl in combination reduced 5‐HIAA values below those obtained with clorgyline alone. It is concluded that very little 5‐MeODMT or other 5‐methoxyindoleamines are formed endogenously in rat brain, and that the stereotyped syndrome of hyperactivity and tremors produced in rats by pretreatment with MAO inhibitors and L‐tryptophan is dependent on the formation of an N‐substituted derivative of 5‐HT which is at least partly deaminated by MAO‐B to 5‐HIAA.
EFFECT OF OUABAIN AND PHENOBARBITAL ON THE KINETICS OF CORTICAL METABOLIC TRANSIENTS ASSOCIATED WITH EVOKED POTENTIALS
Authors: Rosenthal M. , LaManna J. C.
Published: October 2006

Abstract—

Evoked potentials, shifts of the steady potential and spreading depression have been shown to be associated with transient changes in the oxidative metabolic activity of the cerebral cortex of cats. The metabolic activity is measured at the intact surface by intensity of the fluorescence emitted at 460 nm when the tissue is illuminated at 366 nm. The intensity of the fluorescence signal is related to the oxidationreduction level of intramitochondrial NADH which is, itself, related to the ATP/ADP ratio and the rate of oxygen consumption.

In this study, the transient changes in metabolic activity with evoked potentials are separated into component parts by means of kinetic analysis. Ouabain (0.1 mM) introduced directly under the cortical surface, markedly slows the ‘on kinetics’ with no change in recovery metabolism. Phenobarbital delays the reduction of NAD+ (‘off kinetics’) with little effect on ‘on kinetics’.

Thus, the transient fluorometric response to evoked potentials is confirmed as a measure of ATP breakdown and oxidative rephosphorylation. The rate of NADH oxidation is a measure of the rising ADP concentration due to the action of the Na‐K ATPase. The rate of return of the fluorescence to baseline levels (reduction of NADH) is a function of the respiratory chain.
DYNAMICS OF CEREBRAL METABOLISM DURING MODERATE HYPERCAPNIA1
Authors: Kogure K. , Busto R. , Scheinberg P. , Reinmuth O.
Published: October 2006

Abstract—

The effects of hypercapnia on the kinetics of cerebral energy metabolism were evaluated in adult rats by the closed system method of LOWRY et al. (1964). Moderate hypercapnia with a Paco2 of 61 torr sustained for 20 min resulted in intracellular brain acidosis (7.07‐6.97). During hypercapnia the tissue content of glucose increased whereas phosphocreatine, ADP, pyruvate and lactate contents, and the lactate/pyruvate ratio decreased. The ATP/ADP ratio increased from 7.7 to 9.0; the cytoplasmic NADH/NAD + ratio decreased from 2.06 × 10‐3 to 1.49 × 10‐3. There was no change in Energy Charge. Turnover rate of phosphocreatine increased from 3.84 to 4.62 mmol/kg/min, but the turnover rates of ATP, glucose and glycogen were reduced (from 1.98 to 1.86, 6.24 to 4.80, and 3.96 to 2.94 mmol/kg/min, respectively). The utilization rate of total high energy phosphate decreased from 30.6 to 25.4 mmol/kg/min while the post‐decapitation EEG during hypercapnia persisted longer than during normocapnia. These results indicate that moderate hypercapnia reduces the overall kinetic activity of cerebral energy metabolism. The steady Energy Charge suggests that the reduction in the rate of high energy phosphate use is proportionally balanced by a lowered production rate of ATP.
SPINAL CORD LIPIDS AND MYELIN COMPOSITION IN BORDER DISEASE (HYPOMYELINOGENESIS CONGENITA) OF LAMBS
Authors: Patterson D. S. P. , Terlecki S. , Foulkes J. A. , Sweasey D. , Glancy E. M.
Published: October 2006

Abstract—

Spinal cords from clinically affected newborn lambs, each with muscular spasms (‘shaking’) and a ‘hairy’ birth coat, were found to be deficient in DNA and to contain less myelin and various lipid components, suggesting retarded CNS development equivalent to about 124 days conceptual age. Cerebrosides were notably deficient in whole cord and isolated myelin and contained more saturated and less unsaturated fatty acids than normal. The rate of cerebroside synthesis assayed in vitro was enhanced and taken with the very low tissue concentrations this indicated faster cerebroside turnover and a less stable myelin in the spinal cords of lambs affected with Border Disease. Marked decreases in plasmalogen concentrations, the redistribution of phospholipid fractions, the presence of about 8 per cent cholesterol in the esterified form and the characteristic fatty acid composition of these esters strongly suggest that degeneration is concomitant with myelin immaturity. Hypocupraemia, low concentrations of copper in the cerebrum and increased concentrations in spinal cord myelin are additional features of the clinical disease. The latter result may be related to myelin immaturity.
EVIDENCE FOR A SINGLE CATALYTIC BINDING SITE ON HUMAN BRAIN TYPE B MONOAMINE OXIDASE
Authors: Roth J. A.
Published: October 2006

Abstract—

The tricyclic antidepressant drug, amitriptyline, inhibited the B form of human brain mitochondria] monomine oxidase (MAO) under normal atmospheric conditions in a noncompetitive manner when phenylethylamine (PEA) was used as substrate and competitively when benzylamine (BzNH2) was employed as substrate. In addition, it was also found that PEA and BzNH2 inhibited each other's degradation noncompetitively. Similar results have previously been reported with human platelet MAO. These data suggest that the catalytic binding sites for PEA and BzNH2 on the B form of human brain MAO may be different. Attempts were made to further distinguish these catalytic binding sites on the brain oxidase using the irreversible MAO inhibitors, pargyline and clorgyline. Though these drugs have considerably different affinities for the B form of the oxidase, the degree to which either compound inhibited PEA or BzNH2 deamination was essentially identical. When incubations were performed at elevated oxygen concentrations PEA and BzNH2 became mutually competitive inhibitors of each other's metabolism. Also at the higher levels of oxygen, amitriptyline inhibition of PEA deamination approached a competitive fashion. These results suggest that PEA and BzNH2 share a common catalytic binding site on the B form of MAO and, in addition, bind to an inhibitory site on the reduced form of the oxidase. Accordingly, the data indicate that amitriptyline also binds to both the oxidized and reduced forms of this human brain oxidase.
NEUROCHEMISTRY OF THE SPINAL CORD IN CONGENITAL TREMOR OF PIGLETS (TYPE AII), A SPINAL DYSMYELTMOGENESIS OF INFECTIOUS ORIGIN
Authors: Patterson D. S. P. , Done J. T. , Foulkes J. A. , Swfasey D.
Published: October 2006

Abstract— In piglets affected with congenital tremor type AII the CNS was not morphologically underdeveloped; spinal cord weight, total DNA content and fat‐free dry matter differed little from control values. However the total lipid extractable from affected spinal cords was only about 63% of values established for normal newborn piglets. In particular, the cerebroside content (a myelin‐specific lipid) was reduced to about 30% of the ‘normal’ value. This was parallelled by the results of an in vitro assay of cerebroside synthesis from [3H]galactose which indicated a metabolic impairment. The altered fatty acid profile of isolatcd cerebrosides further suggested a derangement of fatty acid synthesis. Unlike the spinal cords of normal newborn piglets, tissues from affected piglets contained significant amounts of cholesterol esters carrying the characteristic fatty acids associated with demyelination. This implied that the reduced quantities of possibly abnormal myelin were unstable. Abnormal swollen oligodendrocytes were commonly present in the spinal cords of affected piglets and this was consistcnt with the observed impairment of myelin formation.
NEUROTOXICITY OF A NON‐METABOLIZABLE AMINO ACID, 1‐AMINOCYCLOPENTANE‐l‐CARBOXYLIC ACID: REGIONAL PROTEIN LEVELS AND LIPID COMPOSITION OF NERVOUS TISSUE
Authors: Nixon R. A.
Published: October 2006

Abstract— The non‐metabolizable amino acid, 1‐aminocyclopentane‐l‐carboxylic acid (ACPC), when administered to mice, induces primary degeneration of axons in the cerebellum, rostral spinal cord and peripheral nerves. One to 4 weeks after a single intraperitoneal injection of ACPC (0.5–2 mg/g body wt) in adult mice, the fresh and dry weights of brain, cerebellum and spinal cord were reduced compared with those of normal and pair‐fed controls. The protein content of all CNS regions, but particularly that of the cerebellum and cervical spinal cord, was lowered in ACPC‐treated mice relative to that of normal controls. Sciatic nerve protein was also decreased in mice following 2 mg/g of ACPC. Pair‐fed controls exhibited protein deficits in the cerebellum and cervical spinal cord but to a significantly smaller degree. In ACPC‐treated mice, the sulfatide content of spinal cord and peripheral nerve was reduced but that of brain was normal. Sphingomyelin levels in these three regions increased except in the brains of mice given 0.5 mg/g of ACPC where the levels fell.

The protein and sulfatide deficits were greatest in the regions which are known to exhibit the highest proportion of degenerating nerve fibers. The correlation of ACPC treatment with protein and sulfatide loss is consistent with the reported disruptive effects of ACPC on protein metabolism and with the involvement of proteins in sulfatide. metabolism. The protein deficits in pair‐fed mice are considered in relation to the exacerbating effect of reduced dietary protein intake on ACPC neurotoxicity.
CONTENTS OF SEVERAL AMINO ACIDS IN THE CEREBELLUM, BRAIN STEM AND CEREBRUM OF THE ‘STAGGERER’, ‘WEAVER’ AND ‘NERVOUS’ NEUROLOGICALLY MUTANT MICE1
Authors: McBride W. J. , Aprison M. H. , Kusano K.
Published: October 2006

Abstract—

The content of glutamate, GABA, aspartate, glycine and alanine was determined in the cerebellum, brain stem and cerebrum of three different mutant mice which have been named ‘staggerer’, ‘weaver’ and ‘nervous’ on the basis of neurological symptoms. In the ‘staggerer’ and ‘weaver’ mutants there is an almost complete absence of granule cells in the cerebellar cortex while in the ‘nervous’ mutant there is a loss of Purkinje cells (and to a lesser extent a loss of granule cells) in the cerebellar cortex. In the cerebellum of the ‘weaver’ mutant, the content of glutamate was signficantly lower (P < 0.025) than control values (8.77 ± 0.76 vs 12.0 ± 1.3 μmol/g tissue wet wt) and the contents of GABA and glycine were significantly greater than normal levels. In the cerebellum of the ‘staggerer’ mutant, the content of glutamate was significantly lower (6.62 ± 0.70 μmol/g) and the contents of glycine and alanine significantly higher than control values. In the cerebrum and brain stem regions of the staggerer mutant, weaver mutant and the normals the contents of the five amino acids were the same. The contents of glycine and alanine in the cerebellum, GARA and glycine in the brain stem and GABA and alanine in the cerebrum of the nervous mutants were higher than control values. The data are discussed in terms of a possible role for glutamate functioning as an excitatory transmitter when released from the cerebellar granule cells.
DIFFERENTIAL DISTRIBUTION OF [U‐14C]GLUCOSE AND [U‐14C]GLYCEROL AMONG MOLECULAR SPECIES OF PHOSPHATIDYL CHOLINE, PHOSPHATIDYL ETHANOLAMINE AND 1,2‐DIACYLGLYCEROL IN RABBIT BRAIN12
Authors: Bralining Christiane , Gercken G.
Published: October 2006

Specific radioactivities of molecular species of phosphatidyl choline(PC), phosphatidyl ethanolamine(PE) and 1,2‐diacylglycerol were determined in rabbit brain 15 and 30 min after intraventricular injection of 10OpCi of either [U‐14C]glucose or [U‐14C]glycerol. The rate of de nouo synthesis of glycerophospholipids and their molecular species could be determined after glycerol labelling, since 94.0–99.7% of 14C activity was recovered in glyceryl moieties of brain lipids. After injection of glucose radioactivity was measured in both glyccrol and acyl residues of lipids.

High incorporation rates were measured in species of PC, PE and 1,2‐diacylglycerol with oleic acid in position 2 and with palmitic, stearic or oleic acids in position 1. The conclusion may therefore be drawn that these molecular species were preferably synthesized de novo by selective acylation of glycerol 3‐phosphate. The lowest specific activities were observed for 1,2‐dipalmitoyl‐ and l‐stearoyl‐2‐ arachidonoyl‐glycerol, ‐PC and ‐PE. These turnover rates point to incorporation of arachidonate, and probably also of palmitate in dipalmitoyl‐PC, amounting to 20% of total PC, via deacylation‐acylation‐ cycle.
A MASS FRAGMENTOGRAPHIC ASSAY OF 3‐METHOXYTYRAMINE IN RAT BRAIN
Authors: Galli C. L. , Cattabeni F. , Eros T. , Spano P. F. , Algeri S. , Giulio A. Di , Groppetti A.
Published: October 2006

Abstract— A mass fragmentographic method for the measurement of 3‐methoxytyramine, a metabolite of dopamine formed after its neuronal release, is described. This method allows the assay of this dopamine metabolite in the picogram range, thus utilizing only few milligrams of brain areas containing dopaminergic neurons. Moreover, the method is simple and possesses the high specificity intrinsic to mass fragmentography.
EFFECTS OF CALCIUM AND MAGNESIUM DEFICIENCY ON THIAMINE DISTRIBUTION IN RAT BRAIN AND LIVER
Authors: KIMURA M. , ITOKAWA Y.
Published: October 2006

Abstract—

Wistar rats were divided into 4 groups and the following different synthetic diets were given for 1 month: group 1, calcium‐ and magnesium‐deficient; group 2, calcium‐deficient, magnesium‐sufficient; group 3, calcium‐sufficient, magnesium‐deficient; group 4, calcium‐sufficient, magnesium‐sufficient (normal diet). After 1 month on these dietary regimens, the rats were killed. In calcium‐deficiency (groups 1 and 2), thiamine concentration in synaptosomal and myelin‐membrane fractions in the brain had decreased and the ratio of free thiamine to total thiamine and non‐protein bound thiamine amount had increased in the brain. In magnesium‐deficiency (groups 1 and 3), thiamine concentration in the liver and activities of thiamine‐dependent enzymes in liver had decreased. These results indicate that calcium plays a role in binding thiamine in nerve membrane structures, which have a specific role in the conduction process of nervous tissues. In contrast, magnesium has little effect on thiamine in nervous tissues but may play an important role in thiamine‐dependent enzyme systems in the liver.