bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective 5‐HT1B receptor inhibition of glutamatergic and GABAergic synaptic activity in the rat dorsal and median raphe
Authors: Lemos Julia C. , Pan Yu‐Zhen , Ma Xiaohong , Lamy Christophe , Akanwa Adaure C. , Beck Sheryl G.
Published: December 2006

The dorsal (DR) and median (MR) raphe nuclei contain 5‐hydroxytryptamine (5‐HT) cell bodies that give rise to the majority of the ascending 5‐HT projections to the forebrain. The DR and MR have differential roles in mediating stress, anxiety and depression. Glutamate and GABA activity sculpt putative 5‐HT neuronal firing and 5‐HT release in a seemingly differential manner in the MR and DR, yet isolated glutamate and GABA activity within the DR and MR has not been systematically characterized. Visualized whole‐cell voltage‐clamp techniques were used to record excitatory and inhibitory postsynaptic currents (EPSC and IPSC) in 5‐HT‐containing neurons. There was a regional variation in action potential‐dependent (spontaneous) and basal [miniature (m)] glutamate and GABAergic activity. mEPSC activity was greater than mIPSC activity in the DR, whereas in the MR the mIPSC activity was greater. These differences in EPSC and IPSC frequency indicate that glutamatergic and GABAergic input have distinct cytoarchitectures in the DR and MR. 5‐HT1B receptor activation decreased mEPSC frequency in the DR and the MR, but selectively inhibited mIPSC activity only in the MR. This finding, in concert with its previously described function as an autoreceptor, suggests that 5‐HT1B receptors influence the ascending 5‐HT system through multiple mechanisms. The disparity in organization and integration of glutamatergic and GABAergic input to DR and MR neurons and their regulation by 5‐HT1B receptors may contribute to the distinction in MR and DR regulation of forebrain regions and their differential function in the aetiology and pharmacological treatment of psychiatric disease states.
Brain activity associated with fear renewal
Authors: Bruchey A. K. , Gonzalez‐Lima F.
Published: December 2006

This is the first mapping study of the brain activity associated with the renewal of an extinguished conditioned response. Rats were given radiolabeled fluorodeoxyglucose, a glucose analog, to map brain effects of an extinguished tone during context‐dependent renewal of conditioned fear. A tone conditioned stimulus was paired with a footshock unconditioned stimulus in a first context, followed by conditioned response extinction in a second context and conditioned response renewal in a third context. Control rats were treated identically, except that tone and shock were presented pseudorandomly. Compared with control subjects, rats with conditioned response renewal had increased tone‐evoked fluorodeoxyglucose uptake in the auditory system (auditory cortex, medial geniculate, inferior colliculus and lateral lemniscal nuclei), as well as somatic and visceral sensory nuclei (external cuneate, spinal trigeminal, solitary tract and vestibular nuclei). In addition, perirhinal cortex, anterior lateral hypothalamus and ventrolateral periaqueductal gray showed conditioned response renewal effects. Brain–behavior correlations indicated that the activity of the external cuneate nucleus strongly predicted the conditioned response in the renewal group. It is suggested that context‐dependent fear renewal is associated with (1) tone‐evoked activation of the excitatory conditioned stimulus representation in the auditory system, (2) associative activation of the unconditioned stimulus representation in somatic and visceral sensory nuclei in the absence of the unconditioned stimulus, and (3) neural activation of the perirhinal cortex, hypothalamus and periaqueductal gray. These findings support Pavlov's stimulus‐substitution theory as a neural mechanism contributing to the renewal effect.
Periodicity and frequency coding in human auditory cortex
Authors: Hall Deborah A. , Edmondson‐Jones A. Mark , Fridriksson Julius
Published: December 2006

Understanding the neural coding of pitch and frequency is fundamental to the understanding of speech comprehension, music perception and the segregation of concurrent sound sources. Neuroimaging has made important contributions to defining the pattern of frequency sensitivity in humans. However, the precise way in which pitch sensitivity relates to these frequency‐dependent regions remains unclear. Single‐frequency tones also cannot be used to test this hypothesis as their pitch always equals their frequency. Here, temporal pitch (periodicity) and frequency coding were dissociated using stimuli that were bandpassed in different frequency spectra (centre frequencies 800 and 4500 Hz), yet were matched in their pitch characteristics. Cortical responses to both pitch‐evoking stimuli typically occurred within a region that was also responsive to low frequencies. Its location extended across both primary and nonprimary auditory cortex. An additional control experiment demonstrated that this pitch‐related effect was not simply caused by the generation of combination tones. Our findings support recent neurophysiological evidence for a cortical representation of pitch at the lateral border of the primary auditory cortex, while revealing new evidence that additional auditory fields are also likely to play a role in pitch coding.
Reduced presynaptic efficiency of excitatory synaptic transmission impairs LTP in the visual cortex of BDNF‐heterozygous mice
Authors: Abidin Ismail , Köhler Torben , Weiler Elke , Zoidl Georg , Eysel Ulf T. , Lessmann Volkmar , Mittmann Thomas
Published: December 2006

The neurotrophin brain‐derived neurotrophic factor (BDNF) plays an important role in neuronal survival, axonal and dendritic growth and synapse formation. BDNF has also been reported to mediate visual cortex plasticity. Here we studied the cellular mechanisms of BDNF‐mediated changes in synaptic plasticity, excitatory synaptic transmission and long‐term potentiation (LTP) in the visual cortex of heterozygous BDNF‐knockout mice (BDNF+/–). Patch‐clamp recordings in slices showed an ∼ 50% reduction in the frequency of miniature excitatory postsynaptic currents (mEPSCs) compared to wild‐type animals, in the absence of changes in mEPSC amplitudes. A presynaptic impairment of excitatory synapses from BDNF+/– mice was further indicated by decreased paired‐pulse ratio and faster synaptic fatigue upon prolonged repetitive stimulation at 40 Hz. In accordance, presynaptic theta‐burst stimulation (TBS) failed to induce LTP at layer IV to layers II‐III synapses during extracellular field‐potential recordings in BDNF+/– animals. Changes in postsynaptic function could not be detected, as no changes were observed in either the amplitudes of evoked EPSCs, the ratios of AMPA : NMDA currents or the kinetics of evoked AMPA and NMDA EPSCs. In line with this observation, an LTP pairing paradigm that relies on direct postsynaptic depolarization under patch‐clamp conditions could be induced successfully in BDNF+/– animals. These data suggest that a chronic reduction in the expression of BDNF to nearly 50% attenuates the efficiency of presynaptic glutamate release in response to repetitive stimulation, thereby impairing presynaptically evoked LTP in the visual cortex.
Early administration of surfactant in spontaneous breathing with nCPAP: feasibility and outcome in extremely premature infants (postmenstrual age ≤27 weeks)
Authors: KRIBS ANGELA , PILLEKAMP FRANK , HÜNSELER CHRISTOPH , VIERZIG ANNE , ROTH BERNHARD
Published: December 2006

Background:  Spontaneous breathing supported by nasal continuous positive airway pressure (nCPAP) is thought to have some advantages compared with mechanical ventilation in extremely premature infants. In addition, early or prophylactic surfactant administration has been shown to be superior to delayed use. A strategy to combine these two principles was tested in our neonatal intensive care unit (NICU). The aim of this feasibility study was to describe the procedure and compare short‐term results with a historical control.

Methods:  The study took place in a level III NICU. In the observational period all extremely premature infants with clinical signs of moderate to severe respiratory distress syndrome despite nCPAP received 100 mg·kg−1 of a natural surfactant preparation via an intratracheal catheter during spontaneous breathing. In the historical control period those infants were intubated and ventilated to receive surfactant.

Results:  Twenty‐nine of 42 infants fulfilled the criteria and were treated with the new approach. In five cases ventilation with manual bag was necessary after administration of surfactant but all infants could be retransferred to nCPAP within a few minutes. Ten infants were intubated later during the first 3 days. Mortality was 7% in the group of infants treated in this way and 12% in all infants treated during the observational period. Mortality was 35% in the historical control period. Morbidity was within ranges reported by other authors.

Conclusions:  Surfactant administration during nCPAP is feasible. First results indicate that early complications are rare. This warrants a prospective randomized trial.
ProSealTM as an alternative to endotracheal intubation in pediatric laparoscopy
Authors: SINHA APARNA , SHARMA BIMLA , SOOD JAYASHREE
Published: December 2006

Background:  The increasing use of laparoscopic surgery in children mandates a leak‐free airway device during carboperitoneum for which tracheal tubes (TT) have been traditionally used. The pediatric ProSeal is a recent introduction to the laryngeal mask airway (LMA) family. The ProSeal LMA (PLMA) has been successfully used in adult laparoscopic procedures. We hypothesized that the ProSeal can be equally effective in achieving adequate oropharyngeal seal and pulmonary ventilation during elective laparoscopic procedures in children.

Methods:  Sixty ASA I and II children, 6 months to 8 years, scheduled for elective laparoscopic surgeries (duration of carboperitoneum <60 min) were randomly assigned to two groups of 30 each (TT and ProSealTM). Patients at risk of aspiration, difficult airway and upper respiratory tract infection were excluded. Anesthesia technique included 8% of sevoflurane/O2/N2O and neuromuscular blockade. Ventilation was set to 10 ml·kg−1 with positive endexpiratory pressure of 5 cmH2O. Respiratory rate was adjusted to maintain endtidal CO2 (PECO2) between 4.6 and 5.8 kPa (35–45 mmHg). Carboperitoneum was achieved at 10 mmHg. Hemodynamic parameters, peak inspiratory pressure (PIP) and PECO2 were noted at different time points. Chi‐squared test, Mann–Whitney U‐test and Wilcoxan W‐test were applied; P < 0.05 was considered significant.

Results:  There were no statistically significant differences in SpO2 and PECO2 between PLMA and TT groups before and after peritoneal insufflation. Significant change was seen in PIP (cmH2O) from induction to carboperitoneum in both groups (14.3 ± 1.48 in PLMA, 14.2 ± 1.46 in TT to 23.36 ± 1.7 in PLMA, and 23.73 ± 1.9 in TT); and in PECO2 (mmHg), from 32 ± 2.2 to 48 ± 3.6 in PLMA and 30 ± 3.1 to 47 ± 2.8 in the TT group. The changes were not significant; P > 0.05 between the groups. The first‐time success rate for PLMA was 88%, mean oropharyngeal leak pressure was 29 ± 3 cmH2O.

Conclusions:  The pediatric PLMA and TT have comparable ventilatory efficacy for elective short laparoscopic procedures.
Segmental colonic transit studies: comparison of a radiological and a scintigraphic method
Authors: Lundin E. , Graf W. , Garske U. , Nilsson S. , Maripuu E. , Karlbom U.
Published: December 2006

Objective  Colonic transit studies are used to diagnose slow transit constipation (STC) and to evaluate segmental colonic transit before segmental or subtotal colectomy. The aim of the study was to compare a single X‐ray radio‐opaque marker method with a scintigraphic technique to assess total and segmental colonic transit in patients with STC.

Method  Thirty‐one female patients (median age 46 years) with severe constipation and a prolonged or borderline prolonged colonic transit time on radio‐opaque marker study were included in the study. They were subsequently investigated with 111Indium‐DTPA colonic transit scintigraphy, with a median time between the investigations of 4(range 1–27) months. Normal values of healthy female controls were used for comparison.

Results  There was no difference between the two methods in terms of prolonged or normal total colonic transit time. Twenty‐nine of 31 female patients had a prolonged transit time only in one or two segments on the marker study. On scintigraphy, the transit time was prolonged for patients in the left (P < 0.05 to P < 0.001), but not in the right colon. With respect to prolonged or normal segmental transit time, there was a significant difference between the two methods only in the descending colon (P = 0.02). However, the results varied considerably for individual patients.

Conclusion  Segmental colonic delay was a common finding. The two methods gave similar results for groups of patients, except in the descending colon. The variation of the results for individuals suggests that a repeated transit test may improve the assessment of total and segmental transit.
THE OTHER SIDE OF TRUST IN HEALTH CARE: PRESCRIBING DRUGS WITH THE POTENTIAL FOR ABUSE
Authors: MILLER JESSICA
Published: December 2006

Defining a nonpaternalistic yet achievable form of trust in medicine in an era of simultaneous patient empowerment and institutional control has been and remains an important task of bioethics. The ‘crisis of trust’ in medicine has been viewed mainly as the problem of getting patients to trust their health care providers, especially physicians. However, since paradigmatic cases of trust are mutual, bioethicists must pay more attention to physician trust in patients. A physician’s view of the reasonableness of trust in a particular patient is affected not just by his or her relationship with that patient, but also by what is going on institutionally, professionally, legally, and politically with regard to a given treatment or intervention. Since general moral principles are insufficient in determining the moral value and reasonableness of trust in particular instances, I discuss in detail the role of trust and distrust in the specific case of treating patients with medications implicated in drug abuse. I conclude that it is important to become aware, first, of the clinical significance of physician trust and distrust in patients, and second, of the many factors which inform both of these moral attitudes. These two claims together suggest that a central, but overlooked, virtue of medical practice is reflective, context‐responsive trust in patients.
RINKONOMICS: A WINDOW ON SPONTANEOUS ORDER1
Authors: Klein Daniel B.
Published: December 2006

The idea of spontaneous order is here exposited by analogy with roller skating at a roller rink. In the roller rink and in the economy, the key ingredient of spontaneous order is coincidence of interest. This makes the beneficial outcome possible. Central planning is bound to fail if for no other reason than because of the knowledge problem. The meaning of ‘spontaneous’ is discussed, along with the limits of the principle.
Transportation and the Geographical and Functional Integration of Global Production Networks
Authors: RODRIGUE JEAN‐PAUL
Published: December 2006

ABSTRACT  The growing interest in the relationships between transportation and globalization has spurred many inquires in the nature of production, consumption and distribution, especially within transport geography. It is widely acknowledged that improvements in transport and distribution have contributed to significant changes in the geographies of production (and vice versa). In a context of intense global competition and diminishing profit margins, logistics and the formation of global production networks offer additional opportunities to improve the efficiency of production through distribution strategies. The spatial and functional fragmentation of manufacturing and attempts at reducing inventories have led to smaller, more frequent and synchronized shipments, transforming the logistics industry, but placing intense pressures on transport systems to support these flows. The benefits derived from global production networks thus cannot be achieved without improvements in logistics and supply chain management. This article seeks to assess the conditions driving the global forms of production, distribution, and transport mainly by looking at the levels of geographical and functional integration of global production networks in view of the high level of fragmentation observed within them. However, there are still many uncertainties and delays in distribution, which can only be compensated by a better organization of freight distribution systems supporting global production networks.
Temporal Elements in the Spatial Extension of Production Networks
Authors: WOXENIUS JOHAN
Published: December 2006

ABSTRACT  The spatial extension of production networks presents a significant challenge to managers accustomed to reducing lead times by geographically contracting supply chains. This paper extends the theory on time in transportation by defining the elements of transport time, order time, timing, punctuality, and frequency and elaborating on their characteristics. Structured along these elements, it analyses the consequences of extending production networks from within a mature economic region, mainly the EU‐15, U.S., and Japan, first to adjacent and then to nearby and finally distant low‐cost regions. Distance obviously affects the transport quality in all time dimensions. Except for air parcel services that globally match what road transport offers within an economic region, the longer the distance, the lower the time‐related performance. Distant, low‐cost regions, meaning China and India, also imply a polarisation between air and sea transport at opposite ends of the time, cost, and capacity scales. This supply gap restricts the types of products traded. The conceptual framework is illustrated in the setting of a global vehicle manufacturer spatially extending its sourcing. It demands that sequenced sub‐assemblies and small, cheap, and generic components are delivered from the vicinity of each assembly plant. Batched components can be sourced from adjacent regions, but deliveries from longer distances imply storage at pick‐up points to fulfil their time requirements. Hence, the suppliers must offer the manufacturing firm deliveries as if they produce relatively close to the assembly plants.
Global Chain, Local Pain: Regional Implications of Global Distribution Networks in the German North Range
Authors: HESSE MARKUS
Published: December 2006

ABSTRACT  As a consequence of global production networks (GPNs), the associated network of freight distribution has gained increasing significance. Whereas the volume of freight transport is expected to increase further, the supply of infrastructure for the movement and handling of consignments appears limited. Particularly at the interfaces, infrastructure capacity for coping with rising throughput is extremely scarce. Any attempt to widen bottlenecks seems to be risky because it happens at some cost and in a contested political and urban environment. This problem will be discussed in the case of the German North Range, with the Port of Hamburg as the traditional gateway and main port, and a scattered system of secondary interfaces and supporting logistics areas. Local constraints, port competition, and the network logic of global distribution systems are challenging the former monopoly of the port, as are plans for establishing a new deep‐sea port at Wilhelmshaven, 150 km west of Hamburg. At the same time, the traditional policy approach of adapting to the needs of the distribution system is coming to an end, owing to fiscal limits, infrastructure constraints, and the generic logic of the global supply chain. In accordance with the emerging global division of labor, various actors and institutions are involved in the management of the chain, with very different powers and interests. Under these circumstances, the attempt to ensure the main port's position by infrastructure expansion is becoming open to question. This could also be a starting point for rethinking how local and regional places could better respond to the new imperative of logistics and distribution. In this respect, it is the network paradigm that could lead the way to a more balanced, cooperative and competitive regional distribution system.
Ultrastructural features of a Stagonospora species (Ascomycotina) in senescent tissues of perennial ryegrass (Lolium perenne L.)
Authors: PHILIPSON MELVA N.
Published: December 2006

The pycnidium of a Stagonospora sp. observed in degenerating leaf sheath and blade tissues of Lolium perenne L. contained concentric bodies similar to those found in the mycobiont of several lichens and a few other free‐living ascomycetes. These bodies occurred in vegetative hyphae, hyphae of the pycnidial wall, in conidiogenous cells and in conidia and comprised a central electron‐translucent core surrounded by a granular zone and an outer radially orientated fibrillar or lamellar zone. In some cases the entire body was surrounded by a translucent halo. A second feature of the interwoven hyphae of the pycnidial wall was the occurrence of pores connecting adjacent hyphae. These lateral pores appeared identical to pores in septa between cells of individual hyphae, and like them, were associated with Woronin bodies.
AN ENZYME SYSTEM IN RAT BRAIN NUCLEI INCORPORATING AMP INTO POLYADENYLATE
Authors: Dravid A. R. , Pete N. , Mandel P.
Published: December 2006

Abstract— The presence of an ATP polymerizing system has been demonstrated in rat brain nuclei. The enzymic activity was not dependent on DNA, and poly A itself primed the incorporation of AMP into polyadenylate. Poly U did not prime the incorporation of AMP. The incorporation obtained in the presence of ribosomal RNA from rat brain as primer was mainly attributable to terminal attachment of AMP. Actinomycin and inorganic ortho‐phosphate had no effect on the enzymic activity, however, inorganic pyrophosphate, ammonium sulphate and nucleoside triphosphates (GTP, CTP and UTP) were inhibitory. The same nuclear extract of brain, used for the synthetic reaction producing poly A, also degraded the polynucleotide to yield adenosine mono, di and triphosphates.
ON THE INVOLVEMENT OF INORGANIC IONS IN THE EFFECT OF γ‐AMINOBUTYRIC ACID ON BRAIN SEROTONIN AND NOREPINEPHRINE
Authors: Yessaian N. H. , Armenian A. R. , Kazarova E. K. , Buniatian H. Ch.
Published: December 2006

Abstract— The loss of GABA, norepinephrine and serotonin and the uptake of GABA (in the presence of 1 mM‐GABA) and the effect of GABA on the loss of norepinephrine and serotonin were investigated in rat midbrain slices incubated in media of various compositions. In a medium of low Na+ concentration the loss of serotonin from incubated slices was markedly inhibited while that of norepinephrine and GABA was significantly increased. Conversely the most pronounced loss of serotonin from slices was observed on the addition of ouabain to a medium of a balanced ionic composition. Whereas the loss of serotonin from slices increased in a medium of high K+ content, it was significantly reduced after 45 min incubation in a high K+‐low Na+ medium. In all the modified media used, a significant loss of norepinephrine was observed while that of GABA was not affected by the omission of Ca2+ and was slightly reduced in the absence of K+. GABA enhanced the loss of norepinephrine and inhibited that of serotonin in a high‐K+ medium and in one with a balanced ionic composition. A deficiency of Na+ in the medium had a differential effect on the loss of norepinephrine and serotonin similar to that observed with 1 mM‐GABA. These results suggest that Na+ may be of crucial importance in the release of serotonin from midbrain slices and that an enhancement of the Na+ extrusion mechanism at the synaptosomal level may be involved in the effect of GABA on brain monoamines.
RAPID TRANSPORT OF PROTEIN IN THE OPTIC SYSTEM OF THE GOLDFISH1
Authors: Elam J. S. , Agranoff B. W.
Published: December 2006

Abstract— Several amino acids, particularly [3H]proline and [3H]asparagine specifically and efficiently labelled rapidly transported proteins in the goldfish optic nerve and tectum after intraocular injection. Studies with these amino acids showed that the rapidly transported proteins moved as a discrete band at a rate which was temperature‐dependent, and was equal to 70‐100 mm per day at 20°C. Transported protein in the optic tectum was 80 per cent particulate and was found in synaptosomal, mitochondrial, and myelin fractions, but not in purified nuclei or ribosomes.
CHOLESTEROL, CHOLESTEROL ESTERS AND CHOLESTEROL ESTERASE IN THE SCIATIC NERVE DURING DEVELOPMENT OF THE CHICK
Authors: Mezei Catherine , Newburgh R. W. , Hattori T.
Published: December 2006

Abstract— Changes in the contents of cholesterol and cholesterol ester and in the activity of cholesterol esterase (EC 3.1.1.13) in the sciatic nerve of the chick during development were measured. The ratio of cholesterol ester/cholesterol was an inverse function of the activity of the esterase (i.e. when the ratio was high, the activity of the enzyme was low, and vice versa). The synthesis of cholesterol esterase was inhibited after addition of actinomycin D both in ovo and in vitro.
THE DISSOCIATION OF RAT BRAIN MEMBRANES BEARING ACETYLCHOLINESTERASE BY THE NON‐IONIC DETERGENT TRITON X‐100 AND AN EXAMINATION OF THE PRODUCT
Authors: Crone H. D.
Published: December 2006

Abstract— The action of Triton X‐100 on a membrane preparation from rat brain was studied with reference to the solubilization of acetylcholinesterase and the product was characterized by exclusion chromatography. The AChE and membrane protein were readily solubilized to form particles corresponding to a mol. wt. of about 5 × 105. The solubility of these particles depended on the continued presence of the detergent. It was concluded that these soluble particles formed an intermediate stage in organization between membrane‐bound AChE and the soluble protein enzyme, and perhaps represented preexisting lipoprotein subunits of the membranes.
PURIFICATION AND PROPERTIES OF CHOLINE ACETYLTRANSFERASE FROM OX BRAIN STRIATE NUCLEI
Authors: Glover V. A. S. , Potter L. T.
Published: December 2006

Abstract—

Choline acetyltransferase was purified from ox brain striate nuclei by an extraction step at pH 5, cation‐exchange chromatography, fractional precipitation with ammonium sulphate, and chromatography on Sephadex G‐200. The enzyme was obtained free of deacylases and cholinesterases, at specific activities of 01‐0‐3 μmol acetylcholine formed per min per mg protein.

The enzyme was found to be a stable and relatively basic protein, with a molecular weight of 65,000.

In the catalysed reactions, , k1, was about four times k2, and the equilibrium constant was approximately 40. For the forward reaction, the Michaelis constant for each substrate was independent of the concentration of the other (choline = 0‐75 mM; acetyl‐CoA = 10 μM), whereas in the back reaction one substrate increased the affinity for the other (acetylcholine = 0‐75‐5 MM; CoA = 25‐150 μM).

CoA inhibited acetylcholine synthesis by competing with acetyl‐CoA (K1, = 16 μM). Acetylcholine slightly inhibited the forward reaction (e.g. 45 per cent in 200 mM) without competing with choline or acetyl‐CoA. These data indicate an ordered reaction mechanism; acetyl‐CoA probably always binds before choline.
RELATIONSHIP BETWEEN ALTERNATE ROUTES OF TRYPTOPHAN METABOLISM FOLLOWING ADMINISTRATION OF TRYPTOPHAN PEROXIDASE INDUCERS OR STRESSORS1
Authors: Yuwiler A. , Wetterberg L. , Geller E.
Published: December 2006

Abstract— Administration of glucocorticoids to rats increased the activity of hepatic tryptophan peroxidase (EC 1.11.1.4) and lowered brain serotonin. Pretreatment with glucose diminished both of these effects. Administration of allylisopropylacetamide to adrenalecto‐mized rats increased both the activity of tryptophan peroxidase and the level of brain serotonin but had no effect on tryptophan hydroxylase (EC 1.99.1.4) activity in the brain stem. The activity of tryptophan peroxidase was increased by the acute stress of laparotomy and by the chronic stress of a 72‐h fast. Neither stressor affected brain serotonin levels appreciably. These results argue against the proposal that the activity of tryptophan peroxidase activity directly affects synthesis of brain serotonin by diverting tryptophan from the biosynthesis of this monoamine.
SOME NEUROCHEMICAL ASPECTS OF FLUOROCITRATE INTOXICATION1
Authors: Patel A. , Koenig H.
Published: December 2006

Abstract— Some metabolic and biochemical effects of fluorocitrate were studied in vivo in rat brain and cat spinal cord. During the preconvulsant and convulsant phases of fluorocitrate poisoning the contents of free glutamate, glutamine and aspartate declined progressively, while that of alanine increased. Incorporation of 14C from [U‐14C]glucose into these amino acids also decreased, although somewhat more gradually. GABA exhibited a biphasic change, its content rising after an initial decrease while its relative specific activity rose initially and subsequently diminished. Incorporation of 14C from [U‐14C]glucose and [U‐14C]lysine into neural protein declined sharply. The citric acid content rose markedly in rat brain and cat spinal cord. In rat brain the glycogen content declined but ATP and ammonia contents were unchanged. The significance of these results with respect to energy metabolism and the possible mechanism of the convulsions during fluorocitrate poisoning is discussed.
STUDIES ON THE CDP‐ETHANOLAMINE‐1,2‐DIGLYCERIDE ETHANOLAMINEPHOSPHOTRANSFERASE OF RAT BRAIN
Authors: Ansell G. B. , Metcalfe R. F.
Published: December 2006

Abstract— The ethanolaminephosphotransferase (EC 2.7.8.1) of rat brain is found largely in the microsomal fraction and is active towards both diacyl glycerol and alkenyl acyl glycerol. Manganese ions were found to be more effective activators of the enzyme than magnesium ions at low concentrations. The Km for CDP‐ethanolamine was found to be about 2.5 × 10−4 M in the presence of either lipid acceptor and the Km for the two lipid acceptors about 1.6 × 10−3 M. Under the most favourable conditions rates of 270 nmol phosphatidylethanolamine and 70 nmol ethanolamine plasmalogen/mg microsomal protein/h at 39°C were obtained. The effect of temperature on the reaction rate depended on whether diacyl glycerol or alkenyl acyl glycerol was the lipid acceptor. Although diacyl glycerol inhibited the formation of ethanolamine plasmalogen the inhibition was not a simple competitive one. In terms of microsomal protein the activity was maximal during the period of active myelination but at3 days and 150 days of ageitwasat least 50 percent of this maximal activity.
BRAIN GANGLIOSIDE PATTERNS OF VERTEBRATES
Authors: Avrova N. F.
Published: December 2006

Abstract— The ganglioside content in brains of representatives of six vertebrate classes (lamprey, ray, sheat‐fish, carp, frog, triton, tortoise, hen, pigeon, rabbit, rat and monkey) was determined. In most cases a correlation was found between the level of nervous organization and the ganglioside content of brain. In fish and amphibian brain ganglioside concentration is half to one third that in mammalian brain.

Ganglioside composition of higher vertebrate brains (mammals, birds and reptiles) has many similar features. Four main gangliosides with 1‐3 NANA residues in their molecules–G1*, G2, G3 and G4–constitute 80‐90 per cent of total ganglioside NANA. Fractions G2a† Go and G5 are present in much lesser amounts. Species peculiarities in distribution of NANA among different fractions were noted.

The brain gangliosides of lower vertebrates–fish and amphibia–are unusual in having a high proportion of polysialogangliosides, containing 4 and 5 NANA residues, and a lower content of monosialogangliosides. In ray brain a considerable part of gangliosides has a reduced carbohydrate chain.
STUDIES ON SOLUBLE PROTEINS RELEASED FROM THE SYNAPTIC VESICLES OF RAT BRAIN CORTEX
Authors: Matsuda T. , Saito K. , Katsuki S. , Hata F. , Yoshida H.
Published: December 2006

Abstract— The soluble proteins released from the synaptic vesicles of rat cerebral cortex were studied. One fraction (D4) of these proteins was released in parallel with release of acetylcholine when synaptic vesicles were incubated at 37°C for 10 min in isotonic medium. Another fraction (Dj) was liberated from synaptic vesicles when their membranes were ruptured by mild treatment under hyposmotic conditions and freeze‐thawing after release of D1 fraction. Fractions D1 and D2 contained 12 and 9 per cent, respectively, of the total protein in the synaptic vesicles. Some properties of these fractions were investigated by zone electrophoresis and ultracentrifugation, and by measuring their binding capacities for [14C]acetylcholine and various enzyme activities related to acetylcholine metabolism.
BIOSYNTHESIS OF MYELIN PROTEINS IN VITRO1
Authors: Smith Marion E. , Hasinoff Catherine M.
Published: December 2006

Abstract— The rates of uptake of DL‐[1‐14C]leucine into the three classes of protein in myelin isolated from slices of rat brain and spinal cord were determined. Basic protein exhibited the slowest rate of uptake; chloroform‐methanol‐soluble proteolipid protein exhibited intermediate rates and the insoluble protein had the most active uptake. All myelin proteins were less active than the mixture of proteins derived from the non‐myelin fraction. Cyclohexi‐mide (10−3 M) and choramphenicol (5 × 10−3 M) inhibited the incorporation of [1‐14C]leucine into brain proteins by as much as 95 per cent. γ‐Aminobutyric acid had no effect on the system. Chloramphenicol also inhibited the uptake of [1‐14C]acetate into myelin lipids, but cycloheximide did not affect lipid synthesis. These effects were observed on both 35‐day‐oldand 18‐month‐old rats, but the biosynthetic activity was far less in myelin from the older rats. The results are discussed in relation to the structure of myelin. It is suggested that the data best fit models in which lipid and protein are in separate phases in the membrane.
SYNTHESIS, MIGRATION AND TURNOVER OF PROTEIN IN RETINAL GANGLION CELLS
Authors: Karlsson J.‐O. , Sjöstrand J.
Published: December 2006

Abstract— The synthesis, migration and turnover of proteins in retinal ganglion cells of the adult rabbit was studied after intraocular injections of [3H]leucine. It was shown that the isotope was rapidly incorporated into proteins of the retina and some of the proteins were subsequently transported out into the axons of the retinal ganglion cells down to the terminals. This intra‐axonal transport of protein occurred at four different velocities; 150, 40, 6‐12 and 2 mm/day respectively. The two most rapidly migrating phases of axonal transport were predominantly associated with light particulate fractions and had a relatively rapid turnover in the nerve terminals in the lateral geniculate body. The third phase of axonal transport which had a rate of 6‐12 mm/day was possibly associated with the migration of mitochondria. The most slowly migrating proteins in the axon which moved at an average rate of 2 mm/day carried predominantly soluble proteins down to the nerve terminals. A minor part of this phase was metabolized locally in the axon with a half‐life of about 14 days. When this slowly migrating phase had reached the nerve terminals in the lateral geniculate body, it was degraded with a half‐life of 9‐6 days. The different phases of axonal transport were of different magnitudes. As measured from the maximal amount of radioactivity present in the nerve terminals the relative amounts of radioactivity of the four phases were: 1,1 ‐8,1 ‐5 and 8‐5.
SYNTHESIS AND RELEASE OF [14C]ACETYLCH0LINE IN SYNAPTOSOMES
Authors: Haga T.
Published: December 2006

Abstract— Synaptosomes took up [14C]choline, about half or more of which was converted to [I4C]acetylcholine when incubated in an appropriate medium containing 1 to 5 μM‐[14C] choline and neostigmine. The amount of [14C]acetylcholine synthesized in synaptosomes increased in parallel with the increase of Na+ concentration in the incubation medium. The effect of Na+ on the uptake of [I4C]choline into synaptosomes was dependent on the concentration of choline in the incubation medium.

About 25 per cent of [14C]acetylcholine synthesized in synaptosomes was released rapidly into the medium by increasing the K+ concentration in the medium from 5 mm to 35 mm. The change of Na+ concentration hardly affected the release of [14C]acetylcholine. The effect of K+ on the release of [14C]choline was rather small compared to that on [14C] acetylcholine. Ouabain promoted the release of [14C]acetylcholine.
SYNAPTIC PROTEINS AND AXONAL FLOW IN THE PIGEON VISUAL PATHWAY 1
Authors: Cuénod M. , Schonbach J.
Published: December 2006

Abstract— The protein supply of the synaptic ending by its nerve cell body has been studied in the retino‐tectal system of the pigeon. [3H]Leucine was injected into the vitreous humor of one eye and the protein specific activity was determined for subcellular fractions of the retina and optic lobes and for the optic tracts. The results show that the perikaryon supplies newly synthesized proteins to its terminals. Two main waves of labelled macromolecules could be distinguished: one, migrating at a speed of 40 mm/day or more, is directly destined for the synaptic ending while the other, progressing at a rate of 1 mm/day, distributes along the entire axon.
ACTIVITY OF AMINOACYL‐TRANSFER RNA SYNTHETASES IN BRAIN MITOCHONDRIA 1
Authors: Borkowski T. , Charȩziński M.
Published: December 2006

Abstract— The binding capacity for amino acids of low molecular wt. RNAs isolated from mitochondrial and cytoplasmic fractions from brain was studied in the presence of partially purified aminoacyl‐tRNA synthetases obtained from both subcellular fractions. The ability of mitochondrial tRNAs to bind amino acids was greater by about three times in the presence of mitochondrial aminoacyl‐tRNA synthetases than in the presence of cytoplasmic enzymes. In contrast, the amino acid‐binding ability of cytoplasmic tRNA was the same in the presence of mitochondrial enzymes as in the presence of those from the cytoplasm. When homologous (rabbit) and heterologous (calf) tRNAs were tested in the presence of mitochondrial or cytoplasmic enzymes obtained from rabbit brain and a mixture of amino acids, a significant species specificity was seen: in both heterologous systems the highest amount of tRNA binding was only 44‐66 per cent of that obtained with the homologous enzyme system.
UPTAKE AND RELEASE OF NOREPINEPHRINE BY RAT BRAIN TISSUE FRACTIONS PREPARED BY ULTRAFILTRATION 1
Authors: Baldessarini R. J. , Vogt Marcella
Published: December 2006

Abstract— Isolated nerve endings were removed from crude homogenates of rat brain by Millipore filters of pore size 0‐5‐0‐8 μm. Synaptosomes containing L‐[3H]norepinephrine were incompletely removed from a non‐ionic medium by 0‐8 μm pore filters, but were nearly quantitatively removed from Krebs’medium, as demonstrated by density gradient subcellular distribution. In suspension, synaptosomes accumulated labelled norepinephrine. Catecholamine uptake was active; it was inhibited by ouabain, imipramine, cocaine, β‐phenethylamine and amantadine. Bound norepinephrine was released by a high concentration of K+. Nerve endings trapped on ultrafilters behaved very similarly to synaptosomes suspended in Krebs’medium by actively accumulating norepinephrine and serotonin; they also possessed monoamine oxidase activity and norepinephrine was released from them by increased concentrations of K+. Ultrafiltration provides a simple, rapid method of preparing metabolically active synaptosomes.
METABOLITES OF [3H]ACETATE BOUND TO SYNAPTIC VESICLES ISOLATED FROM RAT CEREBRAL CORTEX
Authors: Farrow J. T. , O'Brien R. D.
Published: December 2006

Abstract— Synaptic vesicles were isolated from rat cerebral cortex after an intraventricular injection of [3H]acetate. The labelled substances bound to the synaptic vesicles were released by exposure to acid, separated from the vesicle membranes by Sephadex column chromatography and identified by thin‐layer chromatography and thin‐layer electrophoresis. The three major peaks of radioactivity were glutamate, glutamine and gamma‐aminobutyric acid. Their presence in synaptic vesicles is consistent with the concept of an integration of energy metabolism, membrane regulation and synaptic transmission.
TRANSPORT OF MICROTUBULAR PROTEIN IN AXONS OF RETINAL GANGLION CELLS
Authors: Karlsson J.‐O. , Sjöstrand J.
Published: December 2006

Abstract— Following intraocular injection of [3H]leucine, microtubular protein was isolated by two different methods from the optic pathway of the rabbit. It was found that most of this protein was transported at a slow rate in the axons of retinal ganglion cells. After arrival at the nerve terminals in the lateral geniculate body, the microtubular protein decayed with a half‐life of 9 days.
THE RELEASE IN VIVO OF DOPAMINE SYNTHESIZED FROM LABELLED PRECURSORS IN THE CAUDATE NUCLEUS OF THE CAT
Authors: Riddell D. , Szerb J. C.
Published: December 2006

Abstract— To study the release of dopamine (DA) evoked in vivo from the caudate nucleus, a push‐pull cannula was inserted into the head of the caudate nucleus of cats anaesthetised with pentobarbitone sodium (Nembutal), and the tissue in the vicinity of the cannula tip was continuously irrigated with either l‐[14C]tyrosine or DL‐[14C]3,4‐dihydroxyphenylala‐nine (DOPA). The contents of [14C]DA and of the [14C]acidic metabolites in the perfusates were determined after separation from the labelled precursors by column chromatography, TLC and solvent partition.

During perfusion with radioactive tyrosine, only small quantities of [14C]DA appeared in the effluent while the concentrations of the [14C]acidic metabolites gradually increased during the course of the experiment. When [14C]DOPA was substituted for [14C]tyrosine, the proportion of precursor that was converted to DA and released into the effluent as the amine or as its acidic metabolites was increased ten‐fold.

In an attempt to increase the resting release of [14C]DA, D‐amphetamine, tropolone or pheniprazine were individually added to the perfusion fluid. Each drug increased the content of [14C]DA in the perfusate, but the enhanced release was maintained only when pheniprazine was added during perfusion with [14C]DOPA. Stimulation of the rostral substantia nigra (A5‐5) and the medial forebrain bundle caused, in a majority of experiments, a two‐to five‐fold increase in the concentration of labelled DA in the effluent. Stimulation of the substantia nigra at A4‐0 did not enhance the release of [14C]DA from the caudate nucleus but did enhance the release from the putamen. Since the increase in the output of [14C]DA was independent of changes in the output of labelled acidic metabolites, the evoked release was apparently not attributable to changes in extracellular fluid dynamics.
GLUTAMYL, ASPARTYL AND AMIDE MOIETIES OF CEREBRAL PROTEINS: METABOLIC ASPECTS IN VITRO
Authors: Wherrett J. R. , Tower D. B.
Published: December 2006

Abstract— The total mixed proteins (excluding proteolipids) were isolated from cat cerebral cortex and subjected to acid and enzymic hydrolyses. Analyses on the hydrolysates were carried out by specific enzymic procedures to determine the glutamyl, glutaminyl, aspartyl and asparaginyl composition. The content of total glutamyl and total aspartyl residues was the same in all types of protein samples, with average values of 78 and 58 /miol/100 mg of protein, respectively. In biopsy samples approximately 45 per cent of each total was in the amide form.

Preparation of slices of cerebral cortex for incubation was associated with deamidation in situ of 16 per cent of the protein‐bound glutaminyl residues. The extent of deamidation was not increased by incubation or by prolonged hypoxia and was unaffected by prior anaesthesia or by incubation of slices with 10 mM‐NH4Cl or 40 mM‐malonate. Slices prepared from animals intoxicated with methionine sulphoximine exhibited no deamidation. No deamidation was observed for slices of subcortical white matter, liver, kidney, testis or diaphragm of the cat. Cortical proteins from other species appeared to behave similarly to those of the cat. The 5‐4 μmol of NH3 released/g of fresh cortex could account for about 85 per cent of the endogenous free ammonia regularly encountered in such slices. Hence the labile fraction of protein‐bound glutaminyl amide groups represents, as previously suspected, a major source of endogenous cerebral NH3.

Proteins isolated from cerebral cortical slices incubated with L‐[U‐14C]glutamic acid or L‐[U‐14C]glutamine contained 105 (±0.095) per cent of the total 14C metabolized. The ratios (x 100) of protein to free pool specific radioactivities (c.p.m.μmol) of glutamic acid and of glutamine were in the range 0‐22 to 0‐42, or of the same order as previously reported for other amino acids. Comparable results were obtained with proteins isolated from cerebral cortical slices incubated with 10 mM‐15NH4Cl or L‐[amide‐15N]glutamine or both. In the amide N of protein‐bound glutaminyl residues the atoms per cent excess 15N ranged from 007 to 0‐42. This degree of labelling could be accounted for completely by the turnover of the entire glutaminyl moiety, as indicated by the 14C studies. Simultaneous analyses of free pool NH3 and glutamine suggested that transfer of glutamine from medium to slice involves deamidation as it is taken up and reamidation after entry.
INCREASE IN THE CONTENT OF ADENOSINE 3′5′‐ MONOPHOSPHATE IN MOUSE FOREBRAIN DURING SEIZURES AND PREVENTION OF THE INCREASE BY METHYLXANTHINES
Authors: Sattin A.
Published: December 2006

Abstract— Seizures produced significant elevations of the content of adenosine 3′,5′‐monosphosphate (cyclic AMP) in mouse forebrain in vivo. The content of cyclic AMP doubled at 5 s and had increased four‐ to five‐fold at 90 s after the onset of tonus. Smaller increases were observed when mice were placed in an 02‐enriched atmosphere. The increase in the content in forebrain of cyclic AMP during seizures was significantly reduced in mice that had previously been injected with heophylline or caffeine. The methylxanthines did not alter the initial (pre‐ictal) level of cycIicXMP in mouse forebrain. On the basis of these and previous data, the following hypothesis is proposed to account for the present observations : When seizures produce asphyxia in the forebrain, the consequent dephosphorylation of adenine nucleotides liberates small amounts of free adenosine which may then diffuse out of cells and activate an adenyl cyclase‐linked receptor that is located on plasma membranes and is accessible from the extracellular space.
THE PERMEABILITY OF PINCHED‐OFF NERVE ENDINGS TO SODIUM, POTASSIUM AND CHLORIDE AND THE EFFECTS OF GRAMICIDIN
Authors: Keen P. , White T. D.
Published: December 2006

Abstract—

The passive permeability of synaptosomes to ions was measured by a light‐scattering technique. Synaptosomes were freely permeable to acetate, HCO3_, SCN−and NH4+ and were impermeable to choline and SO42‐.

Gramicidin D selectively increased the permeability of synaptosomes to Na+ and K+ ions.

The relative permeabilities of Na+, K+ and Cl−, measured in the presence of a number of more permeant counter‐ions, was in the ratio 1:19:12. These values are discussed in terms of the source of the resting potential.