bluuebunny/crossref_metadata_2025 huggingface dataset:
Local scour at vertical‐wall abutments under clear‐water flow conditions
Authors: Fael Cristina Maria Sena , Simarro‐Grande Gonzalo , Martín‐Vide Juan‐Pedro , Cardoso António Heleno
Published: October 2006

New clear‐water tests on abutment scour are presented. Thirty‐one tests with sand bed and nine tests with lightweight pumice bed were carried out in a 28‐m‐long, 4‐m‐wide flume. Tests typically lasted for 1 week or more. Vertical‐wall abutments with length‐to‐depth L/d ratios from 9 up to 36 were used. Other test campaigns in the literature are added to the data, focusing on abutments with 2 < L/d < 100. The critical flow for scour inception at the abutment nose is found to decrease as L/d increases. The whole data are analyzed for searching the equilibrium scour depths with different methods. The slope change in the plot of scour depth against the logarithm of time is the method selected. For the group of tests run close to the threshold condition, some trends regarding the dimensionless equilibrium scour depth are (1) dependence on the bed material specific gravity in the sense that pumice tests produce less scour and (2) increase of the scour depth as L/d increases. Finally, the morphology of the scour area in terms of volume and plan dimensions is given by new regression equations.
Intermolecular interactions of H2S with rare gases from molecular beam scattering in the glory regime and from ab initio calculations
Authors: Cappelletti David , Vilela Alessandra F. A. , Barreto Patricia R. P. , Gargano Ricardo , Pirani Fernando , Aquilanti Vincenzo
Published: October 2006

Integral cross sections for collisions of rotationally hot H2S molecules with rare gas atoms (Ne, Ar, and Kr) have been measured, in the collision energy range of 10–60kJmol−1, using a molecular beam apparatus operating under high resolution both in angle and in velocity. A well resolved glory pattern has been measured which permitted the accurate characterization of the intermolecular potentials both at long range (in the attractive region) and at intermediate distances (in the well region). Considering the conditions used in the experiments, the obtained potentials must be considered very close to the spherical averages of the full intermolecular potential energy surfaces. Extensive ab initio calculations have also been carried out in parallel in order to characterize energy minima in the potential energy surfaces and energy barriers associated to the motion of the rare gas atoms around H2S. An assessment of the relative role of the various interaction components has been also attempted: the combined analysis of experimental and theoretical results suggests that H2S-rare gas aggregates are mainly bound by nearly isotropic noncovalent interactions of the van der Waals type.
Activation of methane by gold cations: Guided ion beam and theoretical studies
Authors: Li Feng-Xia , Armentrout P. B.
Published: October 2006

The potential energy surface for activation of methane by the third-row transition metal cation, Au+, is studied experimentally by examining the kinetic energy dependence of this reaction using guided ion beam tandem mass spectrometry. A flow tube ion source produces Au+ primarily in its S01 (5d10) electronic ground state level but with some D3 (and perhaps higher lying) excited states that can be completely removed by a suitable quenching gas (N2O). Au+ (S01) reacts with methane by endothermic dehydrogenation to form AuCH2+ as well as C–H bond cleavage to yield AuH+ and AuCH3+. The kinetic energy dependences of the cross sections for these endothermic reactions are analyzed to give 0K bond dissociation energies (in eV) of D0(Au+–CH2)=3.70±0.07 and D0(Au+–CH3)=2.17±0.24. Ab initio calculations at the B3LYP∕HW+∕6-311++G(3df,3p) level performed here show good agreement with the experimental bond energies and previous theoretical values available. Theory also provides the electronic structures of the product species as well as intermediates and transition states along the reactive potential energy surface. Surprisingly, the dehydrogenation reaction does not appear to involve an oxidative addition mechanism. We also compare this third-row transition metal system with the first-row and second-row congeners, Cu+ and Ag+. Differences in thermochemistry can be explained by the lanthanide contraction and relativistic effects that alter the relative size of the valence s and d orbitals.
Ab initio/Rice-Ramsperger-Kassel-Marcus study of the singlet C4H4 potential energy surface and of the reactions of C2(XΣg+1) with C4H4(XA1g+1) and C(D1) with C3H4 (allene and methylacetylene)
Authors: Mebel A. M. , KisIov V. V. , Kaiser R. I.
Published: October 2006

Ab initio modified Gaussian-2 G2M(RCC,MP2) calculations have been performed for various isomers and transition states on the singlet C4H4 potential energy surface. The computed relative energies and molecular parameters have then been used to calculate energy-dependent rate constants for different isomerization and dissociation processes in the C4H4 system employing Rice-Ramsperger-Kassel-Marcus theory and to predict branching ratios of possible products of the C2(Σg+1)+C2H4, C(D1)+H2CCCH2, and C(D1)+H3CCCH reactions under single-collision conditions. The results show that C2 adds to the double CC bond of ethylene without a barrier to form carbenecyclopropane, which then isomerizes to butatriene by a formal C2 “insertion” into the C–C bond of the C2H4 fragment. Butatriene can rearrange to the other isomers of C4H4, including allenylcarbene, methylenecyclopropene, vinylacetylene, methylpropargylene, cyclobutadiene, tetrahedrane, methylcyclopropenylidene, and bicyclobutene. The major decomposition products of the chemically activated C4H4 molecule formed in the C2(Σg+1)+C2H4 reaction are calculated to be acetylene+vinylidene (48.6% at Ecol=0) and 1-buten-3-yne-2-yl radical [i-C4H3(XA′2),H2CCCCH∙]+H (41.3%). As the collision energy increases from 0to10kcal∕mol, the relative yield of i-C4H3+H grows to 52.6% and that of C2H2+CCH2 decreases to 35.5%. For the C(D1)+allene reaction, the most important products are also i-C4H3+H (55.2%) and C2H2+CCH2 (30.1%), but for C(D1)+methylacetylene, which accesses a different region of the C4H4 singlet potential energy surface, the calculated product branching ratios differ significantly: 65%–69% for i-C4H3+H, 18%–14% for C2H2+CCH2, and ∼8% for diacetylene+H2.
Protein complex formation by acetylcholinesterase and the neurotoxin fasciculin-2 appears to involve an induced-fit mechanism
Authors: Bui Jennifer M. , McCammon J. Andrew
Published: October 2006

Specific, rapid association of protein complexes is essential for all forms of cellular existence. The initial association of two molecules in diffusion-controlled reactions is often influenced by the electrostatic potential. Yet, the detailed binding mechanisms of proteins highly depend on the particular system. A complete protein complex formation pathway has been delineated by using structural information sampled over the course of the transformation reaction. The pathway begins at an encounter complex that is formed by one of the apo forms of neurotoxin fasciculin-2 (FAS2) and its high-affinity binding protein, acetylcholinesterase (AChE), followed by rapid conformational rearrangements into an intermediate complex that subsequently converts to the final complex as observed in crystal structures. Formation of the intermediate complex has also been independently captured in a separate 20-ns molecular dynamics simulation of the encounter complex. Conformational transitions between the apo and liganded states of FAS2 in the presence and absence of AChE are described in terms of their relative free energy profiles that link these two states. The transitions of FAS2 after binding to AChE are significantly faster than in the absence of AChE; the energy barrier between the two conformational states is reduced by half. Conformational rearrangements of FAS2 to the final liganded form not only bring the FAS2/AChE complex to lower energy states, but by controlling transient motions that lead to opening or closing one of the alternative passages to the active site of the enzyme also maximize the ligand's inhibition of the enzyme.
Phototrichogram findings in women with androgenetic alopecia
Authors: Rezan Ekmekci Tugba , Koslu Adem
Published: October 2006

Background/purpose: Androgenetic alopecia (AGA) in women is characterized by diffuse thinning in the frontal and parietal areas of the scalp; preservation of the frontal hairline is norm. Hair over the occipital scalp is preserved. The purpose of this work was to investigate the findings of phototrichogram (PTG) of the affected and the spared areas in women with AGA and to compare them with those of healthy subjects.

Methods: Twenty‐two controls and 60 untreated women with AGA (32 with Ludwig I, 28 with Ludwig II) were included in this study. Hair density, percentages of thin hair, and non‐growing hair were estimated both on the midscalp and on the occiput by using PTG with digital camera attached to a dermoscope.

Results: In the control group, hair density was higher on the midscalp than the occiput. In AGA groups, hair density was lower on the midscalp than the occiput and percentages of thin hair and non‐growing hair were higher on the midscalp than the occiput. These findings were more prominent in Ludwig II group. In the occiput there were findings mimicking the changes seen on the midscalp. These were less striking than those seen on the midscalp yet the difference between the control and Ludwig II group was statistically significant.

Conclusion: We concluded that the hair is not equally distributed on the scalp, the occiput may be affected in females with AGA and further studies are necessary to support these findings.
Hypolithic community shifts occur as a result of liquid water availability along environmental gradients in China's hot and cold hyperarid deserts
Authors: Pointing Stephen B. , Warren‐Rhodes Kimberley A. , Lacap Donnabella C. , Rhodes Kevin L. , McKay Christopher P.
Published: October 2006

Hypolithic cyanobacterial communities occur in hot and cold hyperarid environments but the physical factors determining their diversity are not well understood. Here we report hypolithic diversity and colonization of a common quartz substrate at several hyperarid locations in the ancient deserts of north‐western China, that experience varying mean annual temperature, rainfall and concomitant availability of liquid water in soil. Microscopy and enrichment culture resulted only in Chroococcidiopsis morphotypes which were ubiquitous, but community phylogenetic analysis revealed considerable cyanobacterial and heterotrophic bacterial diversity. Species Richness and Shannon's Diversity Index displayed a significant positive linear correlation with availability of liquid water but not temperature or rainfall alone. Several taxonomic groups occurred only in specific climatically defined locations, while for Chroococcidiopsis, Deinococcus and Phormidium location specific lineages within these genera were also evident. Multivariate analysis was used to illustrate pronounced community shifts due to liquid water availability, although these did not significantly affect the predicted functional relationships within any given assemblage in either hot or cold, wet or dry hyperarid deserts. This study clearly demonstrates that availability of liquid water, rather than temperature or rainfall per se is the key determinant of hypolithic diversity in hyperarid locations, and furthermore that functionally similar yet taxonomically distinct communities occur, characterized by the presence of taxa that are specific to defined levels of aridity.
BIOCHEMISTRY OF CEREBRAL TUMOURS: SODIUM, POTASSIUM, CALCIUM, PHOSPHORUS, MAGNESIUM, COPPER AND SULPHUR CONTENTS OF ASTROCYTOMATA, MEDULLOBLASTOMATA AND GLIOBLASTOMATA MULTIFORME
Authors: Canelas H. M. , De Jorge F. B. , Pereira W. C. , Sallum J.
Published: October 2006

Abstract— Twenty‐nine autopsy specimens of intracerebral tumours (nine astrocytomata, ten medulloblastomata and ten glioblastomata multiforme), as well as samples of peritumoral and apparently normal brain tissue, have been studied for Na, K, P, Ca, Mg, Cu, and S contents.

The tumour tissue, irrespective of the histological characteristics, as compared to the ‘normal’ and perineoplastic tissues, showed higher concentration of Ca, Mg, Cu and S. The peritumoral tissue, regardless of the tumour type, showed a higher concentration of Cu than the ‘normal’ control brain.

The more malignant glioblatomata and medulloblastomata. The Cu levels did not show a significant diference.
THE INVERSE RELATIONSHIP BETWEEN THE ACTIVITY OF PYRIDOXAL KINASE AND THE LEVEL OF BIOGENIC AMINES IN RABBIT BRAIN1
Authors: Ebadi M. S. , Russell R. L. , McCoy E. E.
Published: October 2006

Abstract—

In a series of experiments, an inverse relationship was found to exist between the activity of pyridoxal kinase and the concentrations of brain norepinephrine, dopamine, and serotonin. When the biogenic amine content of the brain is lowered, the activity of pyridoxal kinase rises. Conversely, when the concentration of brain biogenic amines is elevated, a depression occurs in the activity of pyridoxal phosphokinase. This relationship, which resembles an in vivo allosteric inhibition phenomenon, not only is highly suggestive of a definite relation between the brain vitamin B6 content and the metabolism of the biogenic amines, but also suggests that the concentration of brain biogenic amines might control the production of coenzyme pyridoxal phosphate.
COMPARISON OF 5‐HYDROXYINDOLES IN VARIOUS REGIONS OF DOG BRAIN AND CEREBROSPINAL FLUID
Authors: Eccleston D. , Ashcroft G. W. , Moir A. T. B. , Parker‐Rhodes A. , Lutz W. , O'Mahoney D. P.
Published: October 2006

Abstract— —Normal values for the concentration of 5‐HT, 5‐HIAA and tryptophan are established in various regions of the dog brain. After administration of tryptophan by intravenous injection the rise and fall of 5‐HT and 5‐HIAA were estimated at 1, 2 and 4 hr. Best fit quadratic regression curves obtained by computer programme were fitted to the data. Similar tryptophan doses were given to dogs and the 5‐HIAA concentration estimated in the cisternal CSF. Quadratic regression curves fitted to these values show that the concentration of 5‐HIAA in CSF reflects the changes of 5‐HIAA in the brain and in particular in the brain stem. a‐Methyl dopa pretreatment blocked the rise of 5‐hydroxyindoles in brain and CSF and appeared to inhibit tryptophan hydroxylase as well as decarboxylase.
PROTEIN TURNOVER IN CELL‐ENRICHED FRACTIONS FROM RABBIT BRAIN1
Authors: Blomstrand C. , Hamberger A.
Published: October 2006

Abstract— A modification of the available methods was used for preparation of nerve and glia cell‐enriched fractions from rabbit brain and spinal cord. The rate of incorporation of tritiated leucine and the turnover rates of protein during 10 days was studied in the bulkprepared cell fractions. The rate of incorporation into the nerve cell fraction was approximately three times greater than in the glia fraction. The nerve cells had one rapid and one slow phase in decline of radioactivity, while the glial cells were characterized by a more uniform decline. The soluble radioactivity was followed in whole tissue of brain and spinal cord and certain differences between the two were observed.
EFFECTS OF DI‐n‐PROPYLACETATE, AN ANTICONVULSIVE COMPOUND, ON GABA METABOLISM1
Authors: Godin Y. , Heiner L. , Mark J. , Mandel P.
Published: October 2006

Abstract—

The effects on GABA metabolism of an anticonvulsant drug, di‐n‐propylacetate (DPA), were studied. Given intraperitoneally DPA increases the brain GABA content and does not change its biosynthesis from glutamic acid. However, it inhibits in vitro both glutamate decarboxylase and aminobutyrate transaminase (GABA‐T) activities. The inhibition is more pronounced on the GABA‐T and this observation might explain the increase of GABA level.
CONTRIBUTION OF THE PENTOSE CYCLE TO THE METABOLISM OF GLUCOSE IN THE ISOLATED, PERFUSED BRAIN OF THE MONKEY
Authors: Hostetler K. Y , Landau B. R , White R. J , Albin M. S , Yashon D
Published: October 2006

Abstract— Isolated brains from three adult monkeys were perfused for 1 hr with [2‐14C]glucose. Glycogen was isolated from the brain stem, cerebral hemispheres, cerebellum and the hypothalamic area at completion of the perfusions. The distribution of 14C in carbons of the glucose unit of glycogen was determined and from this the contribution of the pentose cycle to metabolism of glucose was calculated. The data indicate a maximum contribution by the pentose cycle of 5–8 per cent in brain. No significant difference was observed in the various portions of brain. Oxygen consumption was noted to be low in relation to the amount of glucose utilized, as measured in these experiments.
INTERRELATIONSHIPS BETWEEN PYRIDOXAL PHOSPHATE AND PYRIDOXAL KINASE IN RABBIT BRAIN1
Authors: Ebadi M. S. , McCoy E. E. , Kugel R. B.
Published: October 2006

—An inverse relationship was demonstrable between the concentration of pyridoxal phosphate and the activity of pyridoxal kinase in rabbit brain. The administration of pyridoxine elevated the concentration of pyridoxal phosphate and decreased the activity of pyridoxal kinase. Conversely, the administration of deoxypyridoxine decreased the concentration of pyridoxal phosphate and increased the activity of pyridoxal kinase. The increase in the activity of pyridoxal kinase by deoxypyridoxine was blocked by actinomycin D or puromycin. These results were interpreted to indicate that the tissue availability of pyridoxal phosphate regulated the activity of pyridoxal kinase.
FORMATION OF SEROTONIN BY ISOLATED SEROTONIN‐CONTAINING NEURONS AND BY ISOLATED NON‐AMINE‐CONTAINING NEURONS
Authors: Cottrell G. A. , Powell B.
Published: October 2006

Isolated giant serotonin‐containing neurons of the cerebral ganglia of Helix pomatia were shown to produce serotonin when incubated with 5‐hydroxytryptophan (5‐HTP) whereas cells of the buccal ganglia, which are non‐amine‐containing cells did not. The rate of production was comparable to that for Ach in the isolated neurons of Aplysia. The significance of these results is discussed.
EFFECT OF INSULIN ON LEVELS AND TURNOVER OF INTERMEDIATES OF BRAIN CARBOHYDRATE METABOLISM IN VIVO
Authors: Strang R. H. C. , Bachelard H. S.
Published: October 2006

Abstract— –The rates of incorporation of 14C from [U‐l4C]glucose into intermediary metabolites have been measured in rat brain in vivo. The time course of labelling of glycogen was similar to that of glutamate and of glucose, which were all maximally labelled between 20 and 40min, but different from lactate, which lost radioactivity rapidly after 20min. The extent of labelling of glycogen (d.p.m./μmol of glucose) was of the same order as that of glutamate at 20 and 40 min after injection of [14C]glucose. However, calculations of turnover rates showed that glutamate turns over some 8‐10 times faster than glycogen. Insulin, intracisternally applied, produced after 4‐5 h a 60 per cent increase in glucose‐6‐P and a 50 per cent increase in glycogen. There was no change in the levels of glucose, glutamate or lactate, nor in the activity or properties of the particulate and soluble hexokinase of the brain. The injection of insulin affected neither the glycogen nor glucose contents of skeletal muscle from the same animals. The effects of insulin on the incorporation of l4C into the metabolites contrasted with its effects on their levels. The specific activities of glycogen and glucose were unchanged and there was a slight but non‐significant increase in the specific activity of glutamate. The time course of incorporation into lactate was unaffected up to 20 min, but a significant delay in the loss of 14C after 20 min occurred as a result of the insulin injection. At 40 min, the specific activity of cerebral lactate was 60 per cent higher in insulin‐treated animals than in control animals. The results are interpreted in terms of an effect of insulin on glucose uptake to the brain, with possibly an additional effect on a subsequent stage in metabolism, which involves lactate.
THE EFFECT OF INJURY ON MONOAMINE CONCENTRATIONS IN THE RAT HYPOTHALAMUS
Authors: Stoner H. B. , Elson Patricia M.
Published: October 2006

Abstract— The monoamine concentrations have been measured in four regions of the brain (hypothalamus, cortex, cerebellum and brain stem) in rats injured by either hind‐limb ischaemia or scald. Both injuries produced a rapid fall in the noradrenaline concentration of the hypothalamus which recovered slowly if the injury was not fatal. This effect of injury was seen after pretreatment with a‐methyl‐p‐tyrosine to inhibit noradrenaline synthesis, indicating an increased rate of utilization of noradrenaline after injury. These injuries did not affect the 5‐hydroxytryptamine concentration in the hypothalamus, but changes were found in the concentration of this monoamine and in that of its metabolite, 5‐hydroxyindole acetic acid, in the brain stem. It is concluded that these forms of injury had specific effects on the brain monoamines. The hypothalamic changes were not secondary to changes in core temperature or to hypotension or hypovolaemia and they are discussed in relation to the impairment of temperature regulation seen in the injured rat.
POTASSIUM ACCUMULATION BY BULK PREPARED NEURONAL AND GLIAL CELLS
Authors: Haljamaue H. , Hamberger A.
Published: October 2006

Abstract— Neuronal and glial cell enriched fractions were prepared by density gradient centrifugation of suspensions from rabbit cerebral cortex. The two cell types were incubated separately in media of extracellular ionic composition. The potassium accumulation was determined from analysis of potassium content of the cells by ultramicro flame photometry. Both neuronal and glial cells were capable of active potassium transport which was inhibited by ouabain (2 × 10−4m). The glial cells could accumulate potassium up to four to five times the concentration of the incubation medium and neurons up to one and a half to two times the medium concentration. The respiration in low potassium media was stimulated 15 per cent for neurons and 85 per cent for glia when potassium was added to a final concentration of 50 mm. The uptake by both neurons and glia showed temperature and sodium dependence. There was a definite magnesium requirement for the potassium uptake, particularly demonstrable for glial cells. Calcium inhibited potassium uptake by glia but stimulated slightly that by neurons.
BRAIN PEPTIDASES: CONVERSION AND INACTIVATION OF KININ HORMONES
Authors: Camargo A. C. M. , Ramalho‐Pinto F. J. , Greene L. J.
Published: October 2006

Abstract— Two enzymes that selectively hydrolyse kinins at pH 7.5 were obtained in partially purified form from the supernatant fraction of homogenates of previously frozen rabbit brain by gel filtration on Sephadex G‐100. The enzymes were detected and their activity estimated by bioassay with the isolated guinea pig ileum The products of the enzymic reactions were identified by high voltage electrophoresis at pH 3.5 and by the determination with the amino acid analyser of the amino acids released from the kinins.

One enzyme, kinin‐converting enzyme, catalyses the hydrolysis of kinin‐10 (Lysbradykinin) and kinin‐11 (Met‐Lys‐bradykinin) into kinin‐9 (bradykinin). It also hydrolyses the aminoacyl‐8‐naphthylamides of methionine, lysine, arginine and leucine. The conversion of kinin‐10 to kinin‐9 was inhibited by puromycin (Ki 3.5 × 10−5 M) These properties are similar to those of brain arylamidases described in the literature.

Kininase, the second enzyme, inactives kinins 9, 10 and 11 by peptide‐bond hydrolysis. Similar rates of release of arginine and phenylalanine were observed for the three kinins, suggesting that kininase acts at the carboxy‐terminus of these peptides.

Our results suggest that brain contains proteases which apparently selectively metabolize polypeptide hormones that exert definite pharmacological effects on the central and peripheral nervous systems.
AMINO ACIDS AS PUTATIVE TRANSMITTERS: FAILURE TO BIND TO SYNAPTIC VESICLES OF GUINEA PIG CEREBRAL CORTEX1
Authors: Rassin D. K.
Published: October 2006

Abstract— The levels of free amino acids in subcellular fractions of guinea pig cerebral cortex have been determined. Putative transmitter amino acids are not bound to synaptic vesicles in a manner analogous to acetylcholine, as shown by the failure of hypo‐osmotic shock to cause a specific release of the excitant and depressant amino acids.
THE EFFECT OF HYPERCAPNIC ACIDOSIS UPON SOME GLYCOLYTIC AND KREBS CYCLE‐ASSOCIATED INTERMEDIATES IN THE RAT BRAIN
Authors: Folbergrová Jaroslava , MacMillan V. , Siesjö B. K.
Published: October 2006

Abstract— In order to study the influence of intracellular pH on the carbohydrate metabolism of brain tissue, the concentrations of glucose, glucose‐6‐phosphate, pyruvate, lactate, citrate, α‐oxoglutarate, malate, glutamate, aspartate and ammonia were measured in rats exposed to 6–40% CO2, for 45 min. Hypercapnia of increasing severity gave rise to progressive increases in the concentrations of glucose, glucose‐6‐phosphate and ammonium ion and to progressive decreases in the concentrations of all metabolic acids measured. The results fit with aH+ inhibition of a rate‐limiting step between glucose‐6‐phosphate and pyruvate, and by inference from the results published by others it may be assumed that this step is the phosphofructokinase reaction. Since the proportionally largest decrease occurred in a α‐oxoglutarate, the results might be compatible either with an inhibition of a second rate‐limiting step such as isocitrate dehydrogenase, or with a loss of α‐oxoglutarate through carboxylation to citrate.
ENZYMES CATALYSING ETHANOL METABOLISM IN NEURAL AND SOMATIC TISSUES OF THE RAT
Authors: Raskin N. H. , Sokoloff L.
Published: October 2006

Abstract— The enzymes catalysing ethanol metabolism, alcohol dehydrogenase (EC 1.l.1.1) and aldehyde dehydrogenase (EC 1.2.1.3), were assayed in a variety of neural and somatic tissues of the rat, the human counterparts of which are known to be vulnerable to excessive ethanol. The activity of alcohol dehydrogenase was assayed by the coupled oxidation of ethanol and reduction of lactaldehyde, a method which we have recently found to be sufficiently sensitive and specific to measure the relatively low levels of activity in whole brain. Detectable activities of these enzymes were found in peripheral nerve, skeletal muscle, retina, optic nerve and various regions of brain, as well as in a variety of non‐neural tissues. The levels of the enzymic activities in all tissues were markedly lower than those of liver, but probably sufficient to perform a local function in the metabolism of ethanol or other endogenous substrates. The activity of alcohol dehydrogenase in the various tissues, like that of liver, was confined to the cytosol and exhibited kinetic properties and responses to inhibitors almost identical to those of the liver enzyme. We consider the results to be consistent with the hypothesis that the pathological effects of alcohol may be related, at least in part, to local mechanisms for the metabolism of alcohol.
QUANTITATIVE CHANGES WITH AGE IN THE DNA CONTENT OF METHYLAZOXYMETHANOL‐INDUCED MICROENCEPHALIC RAT BRAIN1
Authors: Matsumoto Hiromu , Spatz Maria , Laqueur Gert L.
Published: October 2006

Abstract— DNA synthesis in methylazoxymethanol (MAM)‐treated foetal brain was reduced during the first 3 days after the injection of the compound into the mother rat. The MAM‐treated brain grew at almost the normal rate after this period, but the reduction in DNA persisted through maturity of the animal. This difference in DNA content between normal and microencephalic brain was restricted to the cerebral hemispheres. The major increase in DNA content of prenatal brain occurred in the cerebrum, whereas the postnatal increase took place in the cerebellum. jH‐Labelled MAM was incorporated more extensively into foetal brain DNA than into RNA. The half‐life of the MAM‐modified nucleic acids was 4–5 days. We suggest that removal of necrotic cells from the brain may account for the rapid loss of label from nucleic acids.
PROTEIN SYNTHESIS IN NEURONAL PERIKARYA ISOLATED FROM CEREBRAL CORTEX OF THE IMMATURE RAT1
Authors: Kohl H. H. , Sellinger O. Z.
Published: October 2006

Abstract— Homogenates of neuronal perikarya isolated from the cerebral cortex of the 8‐day‐old rat were incubated with [3H]leucine, and the characteristics of the protein synthetic process were studied. Incorporation of leucine into protein was linear up to 90 min, proceeded optimally at pH 7.6 and was stimulated by K+ and NH4+, unaffected by Li+ and inhibited by Na+. Puromycin, cycloheximide, RNAse, sulphhydryl blocking agents and phospholipase A exerted a pronounced inhibition, whereas chloramphenicol and phospholipase C had no effect. About 42 per cent of the total radioactive protein formed in the optimally fortified in uitro system was recovered in non‐sedimentable form. Incorporation into the subcellular fractions of the neuronal perikarya increased steadily with increasing time of incubation. The microsomal fraction acquired the highest specific radioactivity (d.p.m./mg of protein), followed by the mitochondrial and the nuclear + cell debris fractions. The high‐speed soluble fraction exhibited the lowest specific radioactivity.

Although the addition of L‐methionine to a suitably fortified incubation medium inhibited neuronal protein synthesis by about 80 per cent, the addition of D‐methionhe, α‐methyl‐DL‐methionine or L‐tryptophan was relatively ineffective by comparison.
THIAMINE IN NEURAL MEMBRANES ENZYMIC HYDROLYSIS OF THIAMINE DIPHBSPHATE
Authors: Barchi R. L. , Braun P. E.
Published: October 2006

Abstract— The membrane‐associated diphosphatase from rat brain which catalyses the hydrolysis of thiamine diphosphate and nucleoside diphosphate is described. The parallel sub‐cellular distribution of thiamine diphosphatase and nucleoside diphosphatase activity and the equal inhibition of both activities by adenosine methylenediphosphonate, a non‐hydrolysable structural analogue of ADP, suggests that a single enzyme is involved. The divalent cation requirement and basic kinetic properties of this enzyme have been determined. This nucleoside diphosphatase is not activated by ATP.
ISOTOPIC MICROASSAY OF HISTAMINE, HISTIDINE, HISTIDINE DECARBOXYLASE AND HISTAMINE METHYLTRANSFERASE IN BRAIN TISSUE1
Authors: Taylor K. M. , Snyder S. H.
Published: October 2006

Abstract— Microassays are described for histamine, histidine, and the activities of the enzymes histidine decarboxylase (EC 4.1.1.22) and histamine niethyltransferase (EC 2.1.1.8) in brain tissue. The enzymic‐isotopic microassay for histamine is based on the methylation of tissue histamine by added histamine methyl‐transferase and [14C]‐ or [3H]‐labelled S‐adenosyl‐l‐methionine. In a double‐isotopic form of the assay, a tracer of [3H]histamine is employed along with [14C]S‐adenosyl‐l‐methionine, and the ratio [14C]:[3H] reflects the amount of histamine in the sample. Because the methylation of histamine is uniform in brain samples studied, a single isotopic assay with [3H]S‐adenosyl‐l‐methionine as the methyl donor is possible and increases sensitivity, so that 10 pg of tissue histamine can be estimated reliably. The assay for histidine involves decarboxylation of histidine by a bacterial histidine decarboxylase and measurement of the histamine formed by the enzymicisotopic procedure. In the histidine decarboxylase assay, histamine synthesized from added histidine is measured. The assay for histamine methyltransferase involves measuring the formation of [14C]methylhistamine with [14C]S‐adenosyl‐l‐methionine serving as the methyl donor.
DEGENERATION OF CENTRAL AND PERIPHERAL NORADRENALINE NEURONS PRODUCED BY 6‐HYDROXY‐DOPA
Authors: Sachs Charlotte , Jonsson G.
Published: October 2006

—The effects of systemically administered 2,4,5‐trihydroxyphenylalanine (6‐OH‐DOPA) on endogenous noradrenaline, [3H]amine uptake and fluorescence morphology has been investigated in mouse brain, heart and iris. 6‐OH‐DOPA in a dose of 100 mg/kg intraperitoneally caused practically no changes in these parameters. Pretreatment with a potent monoamine oxidase inhibitor (nialamide) led to a pronounced long‐lasting 6‐OH‐DOPA induced reduction in endogenous noradrenaline, [3H]amine uptake and nerve density of noradrenaline nerve terminals both in the central and peripheral nervous system. Histochemically accumulations of noradrenaline were observed in non‐terminal axons. These results strongly support the view that 6‐OH‐DOPA can produce degeneration of both central and peripheral noradrenaline neurons. The degeneration is mediated by decarboxylation of 6‐OH‐DOPA to 6‐OH‐DA, since the effects could be abolished by decarboxylase inhibition. The effect of 6‐OH‐DOPA was selective on noradrenaline neurons in the brain, since neither 5‐hydroxytryptamine nor dopamine neurons were affected, opening up new possibilities for studies on central noradrenaline transmitter mechanisms. In the brain there were pronounced accumulations of noradrenaline in the ascending noradrenaline axons making 6‐OH‐DOPA a powerful tool in the mapping of central noradrenaline pathways.
PARTIAL CHARACTERIZATION OF A NEW MYELIN PROTEIN COMPONENT
Authors: Agrawal H. C. , Burton R. M. , Fishman M. A. , Mitchell R. F. , Prensky A. L.
Published: October 2006

A new protein component has been demonstrated in myelin isolated from rat whole brain and from white matter dissected from bovine, dog and rabbit brain. It is also present in rabbit optic nerve. It does not appear to be present in other subcellular fractions of rat brain. It has a molecular weight of 20,540 ± 490(S.D.), as determined by polyacrylamide gel electrophoresis in sodium dodecyl sulphate. A rapid procedure for the isolation of myelin is also described.
PERMEABILITY OF THE BLOOD‐BRAIN BARRIER TO FRUCTOSE AND THE ANAEROBIC USE OF FRUCTOSE IN THE BRAINS OF YOUNG MICE1
Authors: Thurston Jean Holowach , Levy C. A. , Warren Sheila K. , Jones Elizabeth M.
Published: October 2006

—Fructose levels were determined in plasma and brain of 8‐ to 12‐day‐old mice at intervals after the injection of 30 mmol/kg intraperitoneally; controls received NaCl, 15 mmol/kg. In normal animals brain fructose increased very slowly despite a rapid rise in plasma levels (120 times the control value in 5 min). At 40 min the cerebral level was 1.54 ± 0.23 mmol/kg; the corresponding plasma level was 47.1 ± 4.8 mM. The data suggest that fructose can serve as a source of energy to the brain in times of critical need: during insulin hypoglycemia brain fructose increased to only 0.88 ± 0.05 mmol/kg during the same interval (40 min) despite plasma fructose values equal to those in control animals; also 30 s after cerebral ischemia (decapitation) brain fructose fell from a zero time value of 1.19 ± 0.09 mmol/kg (20 min after fructose injection) to 0.76 ± 0.06 mmol/kg (P= 0.005). Under both circumstances (hypoglycemia and ischemie anoxia) an apparent threshold concentration of fructose for utilization was observed—0.6–0.7 mmol/kg. The most likely explanation for this finding appears to be that this level of fructose was in the extracellular space of the brain. Hexokinase activity in brain homogenates of 8‐ to 12‐day‐old mice with fructose and ATP at concentrations found in vivo and during ischemie anoxia did not appear to be rate‐limiting. We concluded that the major handicap to the use of fructose by the brain was the limited penetration of fructose from the blood to the brain.
FACTORS AFFECTING THE TURNOVER OF CEREBRAL GLYCOGEN AND LIMIT DEXTRIN IN VIVO
Authors: Watanabe H. , Passonneau J. V.
Published: October 2006

The turnover of cerebral glycogen in mice has been investigated by using [U‐14C]glucose as a precursor. The time required for turnover of total glycogen and limit dextrin has been determined in normal animals and animals given phenobarbital or hydrocortisone. In all 3 groups, the turnover time for limit dextrin was twice that of total glycogen. Phenobarbital increased the time for turnover of total glycogen and limit dextrin approximately 2‐fold, whereas hydrocortisone diminished the turnover time of both fractions to one‐half. The accumulation of glycogen during phenobarbital anesthesia (2·5‐fold) is attributed to the decrease in rate of phosphorolysis rather than elevated glycogenesis. The ratio of phosphorylase a to total phosphorylase was significantly decreased in the brains of phenobarbital‐treated mice, while the ratio of glycogen synthetase I to total synthetase activity was not affected. The administration of hydrocortisone had no effect on either the phosphorylase or synthetase of mouse brain. A mathematical model was devised to determine the rate constants for incorporation of labelled glucose into brain glycogen and the subsequent loss of radioactivity. Metabolite levels and enzyme activities have been correlated with the observed changes in glycogen turnover.
INTERACTIVE EFFECTS OF CYCLOHEXIMIDE AND PUROMYCIN IN ALTERING BRAIN POLYRIBOSOMES AND NEURAL AND BEHAVIOURAL RESPONSES TO ELECTROSHOCK IN MICE
Authors: MacInnes J. W. , Luttges M. W.
Published: October 2006

Abstract— Interactive effects of puromycin and cycloheximide on brain polyribosomes and cortical electrical activity were investigated. The time courses of action of the drugs on these parameters, in comparison to their inhibitory actions on protein synthesis, were also observed. The results indicate that the disruption of brain polyribosomes by cycloheximide was independent of its inhibition of protein synthesis, whereas the two processes were closely linked in the case of puromycin. For both the disruption of polyribosomes and the alteration of electrical activity, the order in which the drugs were administered was critical, with preadministration of cycloheximide having a protective effect. In contrast to the massive effect of cycloheximide on brain polyribosomes, the drug had no such effect on polyribosomes from liver.
TRANSPORT, TURNOVER AND DISTRIBUTION OF CHOLINE ACETYLTRANSFERASE AND ACETYLCHOLIN‐ESTERASE IN THE VAGUS AND HYPOGLOSSAL NERVES OF THE RABBIT
Authors: Fonnum F. , Frizell M. , Sjöstrand J.
Published: October 2006

Abstract— The transport, distribution and turnover of choline O‐acetyltransferase (ChAc, EC 2.3.1.6) and acetylcholinesterase (AChE, EC 3.1.1.7) in the vagus and hypoglossal nerves were studied in adult rabbits. The enzymes accumulated proximally and distally to single and double ligatures on both nerves and thus indicated both a proximo‐distal and retrograde flow of the enzymes. Double ligature experiments indicated that only 5–20 per cent of the enzymes were mobile in the axon. The rate of accumulation of both enzymes above a single ligature corresponded to the slow rate of axonal flow provided that all the enzymes were mobile, but to an intermediate or fast flow if only a small part of the enzymes was transported. The distribution of ChAc along the hypoglossal neurons was studied and only 2 per cent of ChAc was confined to cell bodies, 42 per cent was localized to the main hypoglossal nerve trunks and 56 per cent to the preterminal axons and axon terminals in the tongue. The ratio of AChE to ChAc was about 3 in the hypoglossal nerve and 32 in the vagus nerve.

Transection of the hypoglossal nerve was followed by a decrease in the activity of ChAc in the hypoglossal nucleus and nerve and in the axons and their terminals in the tongue. The activity of AChE decreased in the hypoglossal nucleus and nerve but not in the tongue. The half‐life of ChAc in preterminal axons and terminals of the hypoglossal nerve was estimated to be 16‐21 days from the results obtained on transport, axotomy and distribution of the enzyme. Intracisternal injection of colchicine inhibited the cellulifugal transport of both enzymes and led to an increase in enzyme activity in the hypoglossal nucleus.
THE INFLUENCE OF HYPOCAPNIA UPON INTRACELLULAR pH AND UPON SOME CARBOHYDRATE SUBSTRATES, AMINO ACIDS AND ORGANIC PHOSPHATES IN THE BRAIN
Authors: MacMillan V. , Siesjö B. K.
Published: October 2006

Abstract— In order to evaluate the influence of hypocapnia upon the energy metabolism of the brain, lightly anaesthetized rats were hyperventilated to arterial CO2 tensions of 26, 15 and 10 mm Hg respectively, with subsequent measurements of intracellular pH and of tissue concentrations of carbohydrate substrates, amino acids and organic phosphates. At Pco1= 26 there was a moderate increase in the intracellular pH but when the Pco2 was reduced further to 10 mm Hg the intracellular pH returned to normal, or slightly subnormal, values. The reduction in PCo2 was accompanied by increased cerebral cortical concentrations of lactate, pyruvate, citrate, α‐ketoglutarate, malate and glutamate and by decreased aspartate concentrations. It is concluded that the accumulation of metabolic acids explains the normal value for intracellular pH at very low CO2 tensions. Previous results obtained in man indicate that there is an increased anaerobic production of lactic acid in the brain in extreme hypocapnia. At comparable CO2 tensions the present results showed a small fall in phosphocreatine and a small rise in ADP. However, since the ammonia concentrations were normal or decreased and since there was an increase in citrate, the results give no direct support to the hypothesis of an activation of phosphofructokinase. Since the cerebral venous Po2 was reduced to 20 mm Hg at an arterial CO2 tension of 10 mm Hg the accumulation of acids was probably secondary to tissue hypoxia. However, since there was no, or only a very small, increase in the calculated cytoplasmic NADH/NAD+ ratio, it appears less likely that acids accumulated due to lack of NAD+.
EFFECT OF PROTEOLYTIC ATTACK ON THE STRUCTURE OF CNS MYELIN MEMBRANE
Authors: Wood J. G. , Dawson R. M. C. , Hauser H.
Published: October 2006

Rat CNS myelin particles have been incubated with trypin and acetyltrypsin under conditions which ensured a selective and substantial removal of the basic proteins leaving acidic Wolfgram and proteolipid proteins. Some trypsin became associated with the basic protein denuded pellet while no attachment of acetyltrypsin was observed. The removal of basic proteins ‘solubilized’ some myelin and produced a lighter ‘fluff’ layer on top of the myelin pellet, but this amounted to no more than 10 per cent of the total myelin lamellae. Electron microscopy indicated a more dense‐straining interperiod line in a small percentage of lamellae which otherwise remained normal. Selective extraction of complex lipids with solvents of increasing polarity, nuclear magnetic resonance spectra and X‐ray diffraction patterns showed no significant changes on removing basic proteins from myelin. The results are interpreted as suggesting that the basic proteins are not uniformly distributed in myelin but preferentially located in the outside layers of the myelin sheath and that they play little part in stabilizing the bulk of the myelin membrane structure.
GLUTATHIONE PEROXIDASE LEVELS IN BRAIN
Authors: Marchena O. de , Guarnieri M. , McKhann G.
Published: October 2006

Glutathione peroxidase activity in brains of various animals was examined. Enzyme activity was low, approximately 10 nmol of glutathione oxidized min−1 mg protein−1 or less. This result suggests that brain tissues contain insufficient glutathione peroxidase activity to provide protection from peroxidative damage and that an alternative mechanism may be present.
PROTEOLYTIC ENZYMES AND EXPERIMENTAL DEMYELINATION IN THE RAT AND MONKEY
Authors: Smith Marion Edmonds , Sedgewick Linda M. , Tagg Josephine S.
Published: October 2006

Abstract— Visible lesions from monkeys with acute experimental allergic encephalomyelitis (EAE) induced by injection of purified myelin basic protein were assayed for acid proteinase, for a neutral proteinase at pH 6·5, and one lesion was measured for cathepsin A. Acid proteinase was increased to 152–176 per cent of levels in normal‐appearing brain areas, neutral proteinase increased to 220–258 per cent, and the one lesion assayed for cathepsin A was 840 per cent of control. These enzymes were measured in the brain stem of Lewis rats with acute EAE as a result of basic protein injection and compared to Freund's adjuvant‐injected controls. Acid proteinase was increased significantly to an average level of 128 per cent of control, the increase in neutral proteinase was not significant, and cathepsin A levels were 258 per cent of control, a highly significant increase. The rise in cathepsin A levels was not seen until the onset of paralytic symptoms. The brain stem of Wistar rats treated with whole spinal cord which show EAE in a milder form than the Lewis rat did not contain significantly higher enzyme levels than the control. The increases in acid proteinase and cathepsin A in brain stems were compared to levels of these enzymes in lymph nodes of EAE, Freund's adjuvant‐injected controls and uninjected controls. The level of acid proteinase of lymph nodes/g protein did not change appreciably in the course of EAE development in the Lewis and Wistar rats and was about 3–4 times the activity in the brain stem. The cathepsin A in the inguinal lymph nodes of Wistar and Lewis rats injected with whole spinal cord in Freund's adjuvant increases to a level 2× that of the lymph nodes of the uninjected control. The cathepsin A levels in these activated lymph nodes was 6–8 × that of the control brain stem. The lymph nodes of Lewis and Wistar rats injected with Freund's adjuvant alone showed the same increase in cathepsin A as those from rats injected with spinal cord. The brain stem of rats undergoing severe demyelination as a result of chronic administration of triethyl tin did not show the enzyme increases. These results are compatible with the theory that proteolytic enzyme increases in EAE (and probably multiple sclerosis) are due to the invasion of mononuclear cells, some of which are probably lymphocytes. Whether or not these enzymes participate in the actual dissolution of myelin is unknown.
NUCLEAR LOCALIZATION OF S‐100 PROTEIN
Authors: Michetti F. , Miani N. , Renzis G. De , Caniglia A. , Correr S.
Published: October 2006

Abstract— S‐100 protein has been found in the nuclei isolated from the brain cortex of rabbit. The nuclear S‐100 constitutes a small portion (0.55 per cent) of the S‐100 present in the cytosol. Most of the large and pale nuclei appear to contain much more S‐100 than the small and dark ones. The nuclear membrane is permeable in vitro to S‐100 in presence of divalent cations. Three forms of S‐100 occur in subnuclear fractions: free S‐100, present in the soluble protein fraction; labile‐bound S‐100, present in the deoxyribonucleoprotein fraction and stable‐bound S‐100, present in the residual or‘nucleolar’fraction. The localization of the S‐100 in those regions of the nucleus that are most active in RNA synthesis provides basic information for further studies on the possible role of this protein on genomic expression in nervous tissue.
THE LIPID COMPOSITION OF AXONS FROM BOVINE BRAIN1
Authors: DeVries G. H. , Norton W. T.
Published: October 2006

Abstract— Bovine axons derived from myelinated CNS axons were found to have 13.5% lipid. This lipid was composed of 20.1% cholesterol, 20.1% galactolipid, 14.6% ethanolarhine phosphatides (56.4% in the plasmalogen form), 18.3% choline phosphatides (10.0% in the plasmalogen form), 9.3% sphingomyelin, 5.6% phosphatidyl serine and 3.4% phosphatidyl inositol. The bovine axons had 0.33 μg ganglioside NeuNAc/mg dry weight. The axon gangliosides were found to contain the four major types of bovine gangliosides, as well as gangliosides GM2 and GD3. The latter two amounted to 20.9 and 15.8 mole per cent respectively, of total gangliosides. On a molar basis, about one half of the gangliosides were monosialogangliosides, with a decreased contribution by gangliosides GT1 and GD1b relative to ganglioside distributions which have been reported for most other CNS components. The relationship of the bovine axonal lipid composition to bovine white matter and its constituents, as well as to other CNS and PNS axonal preparations is discussed.