bluuebunny/crossref_metadata_2025 huggingface dataset:
Ascorbic Acid Uptake by a High‐Affinity Sodium‐Dependent Mechanism in Cultured Rat Astrocytes
Authors: Wilson John X.
Published: October 2006

Abstract: Ascorbic acid (vitamin C) is synthesized in rodent liver, circulates in the blood, and is concentrated in the brain. Experiments were performed to characterize the mechanism of ascorbate uptake by rat cerebral astrocytes in primary culture. Astroglial uptake of L‐[l4C]ascorbate was observed to be both saturable and stereoselective. In addition, uptake was dependent on both the incubation temperature and the concentration of Na+ because it was largely inhibited by cooling to 4°C, by treatment with ouabain to increase intracellular Na+, and by the substitution of K+, Li+, or N‐methyl‐D‐glu‐camine for extracellular Na+. The affinity for ascorbate was relatively high in cells incubated with a physiological concentration of extracellular Na+, because the apparent Km was 32 μM in 138 mM Na+. However, the affinity for ascorbate was significantly decreased when the extracellular Na+ concentration was lowered. Treatment of astrocytes with dibu‐tyryl cyclic AMP induced stellation and increased the maximum rate of ascorbate uptake by 53%. We conclude that astrocytes possess a stereoselective, high‐affinity, and Na+‐dependent uptake system for ascorbate. This system may regulate the cerebral ascorbate concentration and consequently modulate neuronal function.
Modulation of Tryptophan Hydroxylase Activity by Phospholipids: Stimulation Followed by Inactivation
Authors: Imai Yoshinori , Yamauchi Takashi , Fujisawa Hitoshi
Published: October 2006

Abstract: The activity of tryptophan hydroxylase from the rat brainstem was stimulated rapidly three‐ to fourfold by the addition of phosphatidylinositol or phosphatidylserine. However, the activity of the enzyme once stimulated was decreased gradually by subsequent incubation with the phospholipid at 37°C, reaching a level below the original activity after 1 h of incubation. The presence of ferrous ion almost perfectly protected the enzyme against this phospholipid inactivation. The activity of the enzyme inactivated by incubation with the phospholipid was not only restored, but also increased further by incubation at 37°C with ferrous ion and dithiothreitol. Gel filtration analysis revealed that the enzyme stimulated by phosphatidylinositol was eluted in a void volume together with the phospholipid vesicles, but the enzyme inactivated by incubation with phosphatidylinositol was eluted at a later region apart from the vesicles. These results, taken together, suggest the possible involvement of cellular membranes in the regulation of tryptophan hydroxylase in the central nervous system.
Intracellular Storage and Evoked Release of Acetylcholine from Postnatal Rat Basal Forebrain Cholinergic Neurons in Culture with Nerve Growth Factor
Authors: Takei Nobuyuki , Tsukui Hiroko , Hatanaka Hiroshi
Published: October 2006

Abstract: Cholinergic neurons from the septum area, the vertical limb of the diagonal band of Broca, and the nucleus basalis of Meynert of postnatal 13‐day‐old rats were cultured with or without nerve growth factor (NGF) conditions. Total choline acetyltransferase (ChAT) activities, acetylcholine (ACh) contents, and survival numbers of cholinergic neurons in culture from each of three distinct regions were increased by NGF treatment, but little difference was found in cellular ChAT activities and ACh contents obtained in cultures with or without NGF. The result shows that NGF promotes the survival of cholinergic neurons from 13‐day‐old rats. Furthermore, the release of ACh from cultured neurons was investigated. The cells cultured with NGF showed a larger increase of the high K+‐evoked ACh release than those cultured without NGF. However, NGF had no effect on spontaneous release. This suggests that NGF could regenerate and sustain the stimulation‐evoked release mechanisms of ACh in cultured cholinergic neurons from postnatal rats.
Purification and Characterization of Sorbitol Dehydrogenase from Bovine Brain
Authors: Wiesinger Heinrich , Hamprecht Bernd
Published: October 2006

Abstract: Sorbitol dehydrogenase (EC 1.1.1.14) was isolated from bovine brain and purified 3,000‐fold to apparent homogeneity, as judged by polyacrylamide gel electrophoresis. The purified enzyme had a specific activity of 36 units/mg of protein; a molecular weight of 39,000 for each of the four identical subunits and 155,000 for the intact enzyme were determined by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and gel exclusion chromatography, respectively. The presence of one Zn2+ per subunit was confirmed by atom absorption spectroscopy; inactivation of the enzyme by metal‐chelating agents points to the essential role that Zn2+ plays in the catalytically competent enzyme. The enzyme is also inactivated by thiol‐blocking reagents; with respect to inactivation by sodium pyrophosphate, sorbitol dehydrogenase is different from closely related alcohol dehydrogenase.
K‐Opiate Agonists Inhibit Adenylate Cyclase and Produce Heterologous Desensitization in Rat Spinal Cord
Authors: Attali Bernard , Saya Danielle , Vogel Zvi
Published: October 2006

Abstract: The nature of the opiate modulation of adenylate cyclase following acute and chronic agonist exposure has been investigated in rat spinal cord. Using membranes of both adult rat spinal cord and spinal cord‐dorsal root ganglion cocultures, we found that K‐opiate receptors are negatively coupled to adenylate cyclase. The K‐opiate agonists (e.g., U50488) inhibit significantly and dose‐dependently the basal and the forskolin‐stimulated cyclase activities, whereas μ and δ agonists are ineffective. The regulatory action is stereospecific and requires the presence of GTP. EGTA treatment of the plasma membranes abolished the effect of K‐opiate agonists on the basal cyclase activity, and this inhibitory effect could not be restored by subsequent addition of Ca2+. The EGTA treatment did not affect the K agonist inhibition of the forolin‐stimulated cyclase. The results also show that following chronic exposure of cultured cells to etorphine or U50488, there is a loss of K agonist inhibition of the cyclase. Moreover, this desensitization process appears to be heterologous, because α2‐adrenergic agonists (e.g., clonidine or norepinephrine) and the muscarinic agonist (carbachol) exhibited significantly lower potency for inhibiting cyclase activity when compared to untreated cultures. This pattern of heterologous desensitization suggests that chronic exposure to K opiates leads to alterations in postreceptor regulatory components, possibly GTP‐binding proteins.
Prenatal Ontogenesis of Brain Phenolamines and Catecholamines in Relation to Their Metabolizing Enzymes in Roman Avoider Strains of Rats
Authors: Coulon Jean Frangois , Cavoy Albert , Delacour Jean , David Jean‐Claude
Published: October 2006

Abstract: Phenolamines, particularly octopamines, are of special importance in avoidance behavior. In the Roman low avoidance (RLA) strain, p‐octopamine can induce locomotor behavioral activity that is normally observed in the Roman high avoidance (RHA) strain. For these reasons, the levels of prenatal octopamines (para and meta isomers) have been studied in relation to noradrenaline and dopamine levels. In the hypothalamus and brainstem of RHA, a maximum level of the para isomer is observed at 15 days of embryonic development but, unlike in controls and RLA animals, this level remains almost constant until 20 days. For the meta‐isomer and catecholamines, there is a 1‐2‐day delay in detection between controls and RLA or RHA. The study of related enzyme activities reveals that tyrosine hydroxylase displays a 2‐day delay in RHA when compared to the control value at 19 days of fetal life. These results are discussed in terms of the role of p‐octopamine in avoidance conditioning and of the possible delayed expression of the tyrosine hydroxylase gene in Roman strains of rats.
Expression of Calmodulin‐Dependent Phosphodiesterase, Calmodulin‐Dependent Protein Phosphatase, and Other Calmodulin‐Binding Proteins in Human SMS‐KCNR Neuroblastoma Cells
Authors: Pennypacker Keith R. , Kincaid Randall L. , Polli Joseph W. , Billingsley Melvin L.
Published: October 2006

Abstract: Calmodulin (CaM)‐dependent enzymes, such as CaM‐dependent phosphodiesterase (CaM‐PDE), CaM‐dependent protein phosphatase (CN), and CaM‐dependent protein kinase II (CaM kinase II), are found in high concentrations in differentiated mammalian neurons. In order to determine whether neuroblastoma cells express these CaM‐dependent enzymes as a consequence of cellular differentiation, a series of experiments was performed on human SMS‐KCNR neuroblastoma cells; these cells morphologically differentiate in response to retinoic acid and phorbol esters [12‐O‐tetradecanoylphorbol 13‐acetate (TPA)]. Using biotinylated CaM overlay procedures, immunoblotting, and protein phosphorylation assays, we found that SMS‐KCNR cells expressed CN and CaM‐PDE, but did not appear to have other neuronal CaM‐binding proteins. Exposure to retinoic acid, TPA, or conditioned media from human HTB‐14 glioma cells did not markedly alter the expression of CaM‐binding proteins; 21‐day treatment with retinoic acid, however, did induce expression of novel CaM‐binding proteins of 74 and 76 kilodaltons. Using affinity‐purified polyclonal antibodies, CaM‐PDE immunoreactivity was detected as a 75‐kilodalton peptide in undifferentiated cells, but as a 61‐kilodalton peptide in differentiated cells. CaM kinase II activity and subunit autophosphorylation was not evident in either undifferentiated or neurite‐bearing cells; however. CaM‐dependent phosphatase activity was seen. Immunoblot analysis with affinity‐purified antibodies against CN indicated that this enzyme was present in SMS‐KCNR cells regardless of their state of differentiation. Although SMS‐KCNR cells did not show a complete pattern of neuronal CaM‐binding proteins, particularly because CaM kinase II activity was lacking, they may be useful models for examination of CaM‐PDE and CN expression. It is possible that CaM‐dependent enzymes can be used as sensitive markers for terminal neuronal differentiation.
Central Regulation of Adrenal Tyrosine Hydroxylase: Effect of Induction on Catecholamine Levels in the Adrenal Medulla and Plasma
Authors: Regunathan S. , Missala K. , Sourkes T. L.
Published: October 2006

Abstract: The effect of induction of adrenal tyrosine hydroxylase (TH) by various centrally acting drugs on catecholamine levels in adrenal and plasma was investigated in rats. All the drugs tested, namely oxotremorine, Piribedil, B‐HT 920, and HA‐966, produced significant increases in adrenal dopamine content and plasma epinephrine level. Denervation of the adrenal abolished the increase in adrenal dopamine as it did the induction of tyrosine hydroxylase. The results suggest that the induced increase of adrenal TH activity, as mediated by certain drugs, results in an elevation of the plasma epinephrine level and that the adrenal dopamine content is a better indicator of the catecholamine‐synthesizing capacity of the adrenal medulla than are the other catecholamines.
Increased Uric Acid in the Developing Brain and Spinal Cord Following Cytomegalovirus Infection
Authors: Boyes Barry E. , Walker Douglas G. , McGeer Edith G. , O'Kusky John R.
Published: October 2006

Abstract: Tissue concentrations of uric acid were determined in the spinal cord, cerebellum, caudate‐putamen, and cerebral cortex of developing mice following intraventricular inoculation with murine cytomegalovirus (MCMV) on postnatal day 10. Transient signs of neurological impairment were observed in MCMV‐infected animals beginning on days 13–16 and continuing until days 19–21. At the onset of neurological impairment, uric acid concentrations in tissues from infected animals were 17–60‐fold greater than in control animals. On postnatal day 70, 60 days after inoculation and 40 days after resolution of neurological signs, uric acid levels were still two‐ to threefold greater in infected animals. Histological examination revealed signs of focal ischemia in the cerebral and cerebellar cortices of MCMV‐infected mice only at the onset of neurological impairment, with ischemic cell changes in some pyramidal neurons of the cerebral cortex. These results indicate that uric acid may be a sensitive marker of persistent vascular pathology resulting from cytomegalovirus infection of the developing nervous system
Stimulation of the Na+/K+ Pump Activity During Electrogenic Uptake of Acidic Amino Acid Transmitters by Rat Brain Synaptosomes
Authors: Erecińska Maria
Published: October 2006

Abstract: Addition of d‐aspartate, a substrate for the high‐affinity transport of acidic amino acid transmitters, to suspensions of rat brain synaptosomes increased the rate of O2 consumption, uptake of 86Rb, and transport of 2‐[3H]deoxyglucose. Stimulation of all three processes was abolished in the presence of ouabain. d‐Aspartate had no effect on respiration in the medium in which NaCl was replaced by choline chloride. The ratio of the ouabain‐sensitive increase in 86Rb uptake to that in O2 consumption was 12 to 1, which gives a calculated 86Rb(K+)/ATP of 2. It is concluded that electrogenic, high‐affinity transport of sodium‐d‐aspartate into synaptosomes stimulates the activity of the Na+/K+ pump through an increase in [Na+]i.
Release by Electrical Stimulation of Endogenous Glutamate, γ‐Aminobutyric Acid, and Other Amino Acids from Slices of the Rat Medulla Oblongata
Authors: Kihara Minoru , Misu Yoshimi , Kubo Takao
Published: October 2006

Abstract: Evidence was obtained for the release of amino acids by electrical stimulation of slices of regions of the rat medulla oblongata: rostral ventrolateral, caudal ventrolateral, and caudal dorsomedial. There was a Ca2+‐dependent, tetrodotoxin‐sensitive increase in the efflux of aspartate, glutamate, γ‐aminobutyric acid (GABA), glycine, and β‐alanine in all regions examined. There were distinct regional differences in the relative amounts of amino acids released. These results provide evidence for the possible neurotransmitter role of aspartate, glutamate, GABA, glycine, and β‐alanine in these regions of the rat medulla oblongata.
Phosphorylation of Tubulin by Casein Kinase II Regulates Its Binding to a Neuronal Protein (NP185) Associated with Brain Coated Vesicles
Authors: Kohtz D. Stave , Puszkin Saul
Published: October 2006

Abstract: We recently described a new protein associated exclusively with neuronal clathrin‐coated vesicles (CCVs), and characterized two monoclonal antibodies that react with it (S‐8G8 and S‐6G7). In this report, the association of neuronal protein of 185 kilodaltons (NP185) with CCV kinases and its interaction with tubulin are described. The affinity of NP185 for tubulin is significantly enhanced when tubulin is phosphorylated by CCV‐associated casein kinase II. In contrast, phosphorylation of tubulin by a kinase activity associated with purified brain tubulin decreases its affinity for NP185. Together, these data suggest that the interaction of NP185 with tubulin is modulated by protein phosphorylation. Recent evidence has suggested that tubulin is phosphorylated by casein kinase II during neurite development. The enhanced affinity of NP185 for tubulin phosphorylated by casein kinase II could be important for proper intracellular sorting of this protein in the developing neuron.
Molecular Characterization of an Ependymin Precursor from Goldfish Brain
Authors: Königstorfer A. , Sterrer S. , Eckerskorn C. , Lottspeich F. , Schmidt R. , Hoffmann W.
Published: October 2006

Abstract: Ependymins are thought to be implicated in fundamental processes involved in plasticity of the goldfish CNS. Gas‐phase sequencing of purified ependymins β and γ revealed that they share the same N‐terminal sequence. Each sequence displays microheterogeneities at several positions. Based on the protein sequences obtained, we constructed synthetic oligonucleotides and used them as hybridization probes for screening cDNA libraries of goldfish brain. In this article we describe the full‐length sequence of a mRNA encoding a precursor of ependymins. A cleavable signal sequence characteristic of secretory proteins is located at the N‐terminal end, followed directly by the ependymin sequence. Also, two potential N‐glycosylation sites were detected. A computer search revealed that ependymins form a novel family of unique proteins.
Neuroleptic‐Induced Supersensitivity and Brain Iron: I. Iron Deficiency and Neuroleptic‐Induced Dopamine D2 Receptor Supersensitivity
Authors: Ben‐Shachar Dorit , Youdim Moussa B. H.
Published: October 2006

Previous studies have shown that nutritional iron deficiency in rats reduces brain iron content, resulting in dopamine D2 receptor subsensitivity, as indicated by a decrease in [3H]spiperone binding in caudate nucleus and in behavioral responses to apomorphine. Both phenomena can be reversed by iron supplementation. The possibility that neuroleptic‐induced dopamine D2 receptor supersensitivity involves an alteration in brain iron content was investigated in nutritionally iron‐deficient and control rats chronically treated with haloperidol (5 mg/kg daily for 14 or 21 days). Neuroleptic treatment was initiated either (a) concurrently with iron deficiency or (b) 2 weeks after the start of iron deficiency. The results show that dopamine D2 receptor subsensitivity, a feature of iron deficiency, is absent in haloperidol‐treated, iron‐deficient groups. On the contrary, these animals demonstrated biochemical and behavioral dopamine D2 receptor supersensitivity that is relatively greater than that observed with control, haloperidol‐treated animals. Haloperidol (5 mg/kg daily for 21 days) as well as chlorpromazine (10 mg/kg daily for 21 days) caused a significant reduction (20–25%) in liver nonheme iron stores as compared with values in control rats. However, in iron‐deficient rats, in which liver iron stores were almost totally depleted, haloperidol had no effect. The ability of chronic haloperidol treatment to prevent the reduction of dopamine D2 receptor number during iron deficiency may be associated with alteration of body iron status. Thus, less iron may result in an increase in free haloperidol available to the dopamine D2 receptor.
4‐Aminopyridine Increases Acetylcholine Release Without Diminishing Membrane Phosphatidylcholine
Authors: Buyukuysal R. Levent , Wurtman Richard J.
Published: October 2006

4‐Aminopyridine (10‐4–10‐5M) increased severalfold the release of acetylcholine from rat striatal slices superfused with an eserine‐containing, choline‐free medium, and caused stoichiometric decreases in the release of choline. It had no effect on tissue acetylcholine and choline levels. Electrical stimulation of the striatal slices increased acetylcholine release without affecting that of choline. Superfusion of the stimulated slices with 4‐aminopyridine decreased choline release and increased the ratio of acetylcholine to choline in superfusates. As shown previously, electrical stimulation of the striatal slices decreased their contents of phospholipids, principally phosphatidylcholine; 4‐aminopyridine fully protected against these membrane changes. In synaptosomal preparations, 4‐aminopyridine was found to enhance the high‐affinity uptake of [14C]choline and its conversion to [14C]acetylcholine. This effect on choline uptake may underlie 4‐aminopyridine's ability to enhance acetylcholine release in the absence of supplemental choline while suppressing the “autocannibalism” of membrane phospholipids.
Intracarotid 1‐Methyl‐4‐Phenyl‐1,2,3,6‐Tetrahydropyridine Administration: Biochemical and Behavioral Observations in a Primate Model of Hemiparkinsonism
Authors: Guttman Mark , Fibiger Hans C. , Jakubovic Alexander , Calne Donald B.
Published: October 2006

Cynomolgus monkeys received intracarotid injections of the neurotoxin 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) to produce a chronic unilateral model of parkinsonism. Extensive dopamine (DA) depletion was observed in the caudate nucleus and putamen on the side ipsilateral to the injection and this was associated with contralateral tremor, rigidity, and bradykinesia. A dose of 1.25 mg of MPTP caused ipsilateral DA loss of 99.4% in the caudate nucleus, 99.8% in the putamen, and 74.2% in the nucleus accumbens. A dose of 2.5 mg caused ipsilateral DA depletion of 99.3% in the caudate nucleus, 99.5% in putamen, and 90.1% in the nucleus accumbens. The unilateral aspect of the lesion was dose sensitive, with the 2.5‐mg dose causing bilateral asymmetric DA depletion. Tissue concentrations of serotonin were not affected by the toxin. These findings confirm that intracarotid injection of MPTP may produce a useful primate model of hemiparkinsonism that can be associated with selective unilateral DA depletion when the appropriate dose of toxin is used.
Haloperidol‐Induced Increase in Striatal Concentration of the Tripeptide, Tyr‐Gly‐Gly, Provides an Index of Increased Enkephalin Release In Vivo
Authors: Houdi Abdulghani A. , Van Loon Glen R.
Published: October 2006

A sensitive and specific radioimmunoassay has been developed for the tripeptide, Tyr‐Gly‐Gly, which has been shown previously to be an extraneuronal metabolite of opioid peptides derived from proenkephalin A. Using this assay, we found a regional variation in Tyr‐Gly‐Gly immunoreactivity in rat brain, with highest levels in striatum and lowest in cerebral cortex. Intracerebroventricular administration of the aminopeptidase inhibitor, bestatin, produced a threefold increase in Tyr‐Gly‐Gly immunoreactivity in rat striatum, whereas thiorphan, an enkephalinase inhibitor, produced a 45% reduction in striatal Tyr‐Gly‐Gly immunoreactivity. These data suggest that the tripeptide, Tyr‐Gly‐Gly, is in a dynamic state in the brain, and provide further support for the hypothesis that its concentration in specific brain areas may reflect the release of endogenous enkephalins in these brain areas. Further confirmation of the validity of measurements of brain Tyr‐Gly‐Gly as indices of enkephalin release under conditions of altered neuronal activity was provided by our demonstration that chronic dopamine receptor blockade with haloperidol increased striatal concentrations of both Met‐enkephalin and Tyr‐Gly‐Gly.
Differential Sensitivity to Blockade by 4‐Aminopyridine of Presynaptic Receptors Regulating [3H]Acetylcholine Release from Rat Hippocampus
Authors: Fredholm Bertil B.
Published: October 2006

The inhibitory effect of an adenosine analogue, R‐N6‐phenylisopropyl adenosine (R‐PIA), of the cholinergic agonist carbachol, and of morphine on 3H efflux from [3H]choline‐labeled field‐stimulated rat hippocampal slices was compared with that produced by two inhibitors of N‐and L‐type Ca2+ channels, ω‐conotoxin (CgTx; conotoxin GVIA) and cadmium chloride. 4‐Aminopyridine (4‐AP) caused a dose‐dependent increase in evoked transmitter release, with a maximal effect (an almost threefold increase) at 100 μM. 4‐AP (100 μM) did not affect the actions of CgTx, cadmium chloride, and R‐PIA but almost abolished the effect of carbachol and morphine. The present results indicate that presynaptic muscarinic and opiate receptors reduce acetylcholine release by a mechanism that is somewhat different from that used by adenosine A1 receptors. Furthermore, the results indicate that presynaptic A1 receptors on hippocampal cholinergic neurons do not primarily regulate 4‐AP‐dependent potassium channels, but that they might act directly on a Ca2+ conductance.
Up‐regulation of dopamine D2L mRNA levels in the ventral tegmental area and dorsal striatum of amphetamine‐sensitized C57BL/6 mice: role of Cav1.3 L‐type Ca2+ channels
Authors: Giordano T. P. , Satpute S. S. , Striessnig J. , Kosofsky B. E. , Rajadhyaksha A. M.
Published: October 2006

Dopamine D2 long (D2L) and D2 short (D2S) isoforms of the D2 receptor play an important role in psychostimulant‐induced neuronal adaptations. In this study, we used quantitative real‐time PCR to specifically amplify these two splice variants to examine their mRNA expression in the dorsal striatum (dStr), nucleus accumbens (NAc) and the ventral tegmental area (VTA) of amphetamine‐sensitized C57BL/6 mice. We found a significant increase in D2L mRNA in the VTA and dStr of amphetamine‐treated mice that positively correlated with the sensitized locomotor response. We also found a significant increase in D2S mRNA in the VTA. We further examined the role of the Cav1.3 subtype of L‐type Ca2+ channels in up‐regulation of D2L and D2S mRNA in the VTA. Amphetamine‐pretreated Cav1.3 wild‐type (Cav1.3+/+) mice exhibited sensitized behavior and a significant increase in D2L and D2S mRNA compared with saline‐pretreated mice Amphetamine‐pretreated homozygous Cav1.3 knockout (Cav1.3–/–) mice did not exhibit sensitized behavior. There was a significant increase in D2S mRNA, but not D2L mRNA. In conclusion, our results find that amphetamine increases D2L mRNA expression in the dStr and the VTA, an adaptation that correlates with expression of sensitized behavior and dependence on Cav1.3 Ca2+ channels.
2-Deoxy-D-Glucose Maps Movement-Specific Nervous Activity in the Second Visual Ganglion of
Drosophila
Authors: Buchner Erich , Buchner Sigrid , Hengstenberg Roland
Published: October 2006

Adult
Drosophila
were fed with tritium-labeled deoxyglucose prior to a 5-hour period of visual stimulation. A flickering disk of light and a moving grating were presented to the left and right eyes, respectively. Autoradiography revealed enhanced labeling solely in that part of the second optic ganglion (medulla) whose visual field was stimulated by movement.
Myogenic Defect in Acetylcholinesterase Regulation in Muscular Dystrophy of the Chicken
Authors: Linkhart T. A. , Yee G. W. , Wilson B. W.
Published: October 2006

To determine whether inherited muscular dystrophy of the chicken is neurogenic or myogenic in origin, limb buds from homozygous normal and dystrophic chick embryos were exchanged prior to muscle differentiation and innervation. Biceps muscles of hatched chicks, in which muscle of the donor was innervated by nerves of the host, were analyzed for embryonic properties of muscle acetylcholinesterase and for fiber diameter, two distinctive markers for expression of the dystrophic gene. The results indicate that muscular dystrophy of the chicken is caused by an initial biochemical lesion in the limb and its muscle rather than in its innervating nerve.
Pyridoxal Kinase: Decreased Activity in Red Blood Cells of Afro-Americans
Authors: Chern Ching J. , Beutler Ernest
Published: October 2006

The mean pyridoxal kinase activity in red blood cells of American blacks was approximately 50 percent lower than that of American whites. Lymphocytes, granulocytes, and cultured skin fibroblasts from black and white donors contained identical pyridoxal kinase activity. The pyridoxal kinase of blacks was indistinguishable from that of whites with respect to heat stability, chromatographic mobility on microgranular diethylaminoethyl cellulose, Michaelis-Menten constant for pyridoxine, and susceptibility to inhibition by 4-deoxypyridoxine. The difference of the activity of this enzyme in whites and in blacks is much greater than any previously observed biochemical difference between the races.
Inhibition of Catecholamine Release by Tolbutamide and Other Sulfonylureas
Authors: Hsu Chung-Yi , Brooker Gary , Peach Michael J. , Westfall Thomas C.
Published: October 2006

Tolbutamide and other sulfonylureas inhibited spontaneous and nicotine-induced release of catecholamines from the perfused cat adrenal gland and nicotine-induced release of [
3
H]norepinephrine from isolated guinea pig hearts. Of the sulfonylureas tested, the order of potency of this inhibitory effect paralleled the hypoglycemic action. These results raise the possibility that the inhibition of the sympathoadrenal system may contribute in part to the hypoglycemic action of sulfonylureas.
Metaphors Be with You
Authors: Ackerman Diane
Published: October 2006

Contemporary Poetry and Contemporary Science
.
Robert Crawford, Ed.
. Oxford University Press, Oxford, 2006. 250 pp. $35, £19.99. ISBN 9780199258123.

A collection of essays and poems that grew out of a program of events at the Edinburgh International Science Festival.
Supraependymal Cells of Hypothalamic Third Ventricle: Identification as Resident Phagocytes of the Brain
Authors: Bleier Ruth , Albrecht Ralph , Cruce Judith A. F.
Published: October 2006

Cells lying on the ventricular surface of the hypothalamic ependyma of the tegu lizard exhibit the pseudopodial and flaplike processes characteristic of macrophages found elsewhere. Since they ingest latex beads, they may be considered a resident phagocytic system of the brain. The importance of ependyma and ventricular phagocytes as a first line of defense against viral invasion of the brain, as well as their role in the pathogenesis of certain virus-related diseases, is suggested by a number of experimental and clinical observations.
Spatial Variation of Ozone Depletion Rates in the Springtime Antarctic Polar Vortex
Authors: Yung Yuk L. , Allen Mark , Crisp David , Zurek Richard W. , Sander Stanley P.
Published: October 2006

An area-mapping technique, designed to filter out synoptic perturbations of the Antarctic polar vortex such as distortion or displacement away from the pole, was applied to the Nimbus-7 TOMS (Total Ozone Mapping Spectrometer) data. This procedure reveals the detailed morphology of the temporal evolution of column O
3
. The results for the austral spring of 1987 suggest the existence of a relatively stable collar region enclosing an interior that is undergoing large variations. There is tentative evidence for quasi-periodic (15 to 20 days) O
3
fluctuations in the collar and for upwelling of tropospheric air in late spring. A simplified photochemical model of O
3
loss and the temporal evolution of the area-mapped polar O
3
are used to constrain the chlorine monoxide (ClO) concentrations in the springtime Antarctic vortex. The concentrations required to account for the observed loss of O
3
are higher than those previously reported by Anderson
et al.
but are comparable to their recently revised values. However, the O
3
loss rates could be larger than deduced here because of underestimates of total O
3
by TOMS near the terminator. This uncertainty, together with the uncertainties associated with measurements acquired during the Airborne Antarctic Ozone Experiment, suggests that in early spring, closer to the vortex center, there may be even larger ClO concentrations than have yet been detected.
Was Adenine the First Purine?
Authors: Schwartz Alan W. , Bakker C. G.
Published: October 2006

Oligomerization of HCN (1 molar) in the presence of added formaldehyde (0.5 molar) produced an order of magnitude more 8-hydroxymethyladenine than adenine or any other biologically significant purine. This result suggests that on the prebiotic Earth, nucleoside analogs may have been synthesized directly in more complex mixtures of HCN with other aldehydes.
Radiation Measurements Aboard Spacelab 1
Authors: Benton E. V. , Almasi J. , Cassou R. , Frank A. , Henke R. P. , Rowe V. , Parnell T. A. , Schopper E.
Published: October 2006

The radiation environment inside Spacelab 1 was measured by a set of passive radiation detectors distributed throughout the volume inside the module, in the access tunnel, and outside on the pallet. Measurements of the low-LET (linear energy transfer) component obtained from the thermoluminescence detectors ranged from 102 to 190 millirads, yielding an average low-LET dose rate of 11.2 millirads per day inside the module, about twice the low-LET dose rate measured on previous flights of the space shuttle. Because of the higher inclination of the orbit (57° versus 28.5° for previous shuttle flights), substantial fluxes of highly ionizing HZE particles (high charge and energy galactic cosmic rays) were observed, yielding an overall average mission dose-equivalent of about 150 millirems, more than three times higher than measured on previous shuttle missions.
Uranus: Microwave Images
Authors: Jaffe Walter J. , Berge Glenn L. , Owen Tobias , Caldwell John
Published: October 2006

Observations of Uranus at wavelengths of 2 and 6 centimeters with the Very Large Array were made in 1980 and 1981. The resulting maps of brightness temperature show a subsolar symmetry at 2 centimeters but a near-polar symmetry at 6 centimeters. The 6-centimeter maps show an increase in temperature from equator to pole with some evidence for a warm "ring" surrounding the north pole. The disk-average temperatures (147 ± 5 K and 230 ± 6 K at 2 and 6 centimeters, respectively) are distinctly lower than recently reported values; these results suggest that the secular increase in temperature reported during the last 15 years has been reversed. The variations in brightness temperature probably reflect variations in ammonia abundance in the planet's atmosphere, but the mechanism driving these variations is still unclear.
Arteriovenous Anastomoses in the Skin of the Weddell Seal,
Leptonychotes weddelli
Authors: Molyneus G. S. , Bryden M. M.
Published: October 2006

Arteriovenous anastomoses of epithelioid type were demonstrated in Weddell seal skin. The majority occurred just beneath the epidermis and among the hair follicles. There was no significant variation in density of these anastomoses between body and flipper skin. These observations suggest that arteriovenous anastomoses are important in thermoregulation in the Weddell seal, particularly as heat dissipating structures when the animal is out of the water, and that the entire body surface is involved rather than specific regions such as the flippers.
Anomeric Specificity of 3-
O
-Methyl-D-Glycopyranose Against Alloxan Diabetes
Authors: Rossini Aldo A. , Cahill George F. , Jeanloz Dorothy A. , Jeanloz Roger W.
Published: October 2006

The individual α and β anomers of the nonmetabolized glucose analog 3-
O
-methyl-D-glucopyranose (3MG) were studied as protective agents against the alloxan toxicity to pancreatic beta cells in an in vivo rat model. The α 3MG provides greater protection than either the β or the equilibrated compound, as indicated by plasma glucose concentrations 24 hours after the experiment. This specificity suggests that the beta cell membrane is extremely stereospecific, and that glucose or 3MG provide protection against alloxan injury directly by an interaction with the cell membrane and not by subsequent metabolism of the protecting compound.
Locomotory Adaptations in a Free-Lying Brachiopod
Authors: Richardson Joyce R. , Watson Jeanette E.
Published: October 2006

Magadina cumingi
inhabits an environment of high current energy and mobile sediments by using its pedicle in Pogo-stick fashion as an elevating device. This type of progression is associated with pedicle musculature different from that of attached and other free-lying forms, and some diagnostic differences in muscle attachment areas are evident in preservable hard parts.
Reduction of Serum Lipides and Lipoproteins by Ethionine Feeding in the Dog
Authors: Feinberg H. , Rubin L. , Hill R. , Entenman C. , Chaikoff I. L.
Published: October 2006

(i) The effects of daily oral administration of 125 mg of DL-ethionine upon the serum lipides and lipoproteins of dogs were studied. (ii) The feeding of the ethionine resulted in a prompt reduction in the levels of serum fatty acids, phospholipides, and cholesterol. At the end of 25 days, negligible amounts of these lipides remained in serum. (iii) A reduction in the levels of low- and high-density lipoproteins also resulted from the feeding of ethionine. In general, the extent of reduction in all lipoprotein fractions paralleled that observed in lipides. (iv) The removal of ethionine from the diet led to a prompt restoration of the concentrations of all lipide and lipoprotein constituents to normal.
Radio Observations of Meteors
Authors: Millman Peter M.
Published: October 2006

To summarize, we find that the radio technique of meteor observation enables us to extend the systematic recording of meteor rates down to the 9th or 10th magnitude; to determine satisfactory heights and velocities on a scale previously impossible; to calculate the orbits of meteor showers and individual meteors, in particular those that appear only in the daytime; and to study wind drift and fine structure in the ionosphere. The radio observations have quite definitely indicated that down to the 9th magnitude, corresponding to particles approximately 1 mm in diameter, meteors are members of the solar system and do not come from interstellar space.
Significance of Enzymatically Catalyzed Exchange Reactions in Chemotherapy
Authors: Kaplan Nathan O. , Goldin Abraham , Humphreys Stewart R. , Ciotti Margaret M. , Venditti John M.
Published: October 2006

1) 3-Acetyl pyridine has been found to be quite toxic when administered to mice. Simultaneous administration of nicotinamide or DPN protects against the toxicity of acetyl pyridine. Nicotinic acid and tryptophan do not protect animals from the lethal effects of the compound.

2) Nicotinamide inhibits the formation of the 3-acetyl pyridine analog of DPN from acetyl pyridine and DPN in mouse brain homogenates. Nicotinic acid has no inhibitory effect on analog synthesis.

3) Administration of acetyl pyridine results in a fourfold increase in the DPN level of the lever. No acetyl pyridine analog of DPN is found in the liver after injection of the antimetabolite.

4) Injection of acetyl pyridine into tumor mice results in the formation of the acetyl pyridine analog of DPN in the neoplastic tissues. A decrease in DPN concentration is associated with the analog synthesis. The DPN analog has been isolated from tumor tissue and identified.

5) The results are discussed with respect to the significance of enzymatically catalyzed exchange reactions in chemotherapy.
Are the Sciences Too Far Ahead of Advertisers?
Authors: Larrabee C. B.
Published: October 2006

The following editorial by C. B. Larrabee in the periodical
Printers' Ink
for 22 October brings questions that have long troubled scientists to the attention of the general publishing and advertising fraternities. The use of scientific-sounding but scientifically meaningless or misleading language, distortions of scientific thought and experimental results, false analogies both direct and implied—in short, the misuse of science and scientific evidence—can be found in many fields. It is good to see concrete evidence that others are also concerned with the problem.

Incidentally, advertising designed to appear in periodicals serving scientists is generally accurate—more informational than promotional. The readers—the potential buyers—help to control the quality of the advertising.
Enzymatic Conversion of δ-Amino Levulinic Acid to Porphobilinogen
Authors: Granick S.
Published: October 2006

An enzyme has been found in extracts of chicken erythrocytes which converts δ-amino levulinic acid to the monopyrrole porphobilinogen. Some of its properties have been described.
Voluntary Nerve Signals from Severed Mammalian Nerves: Long-Term Recordings
Authors: De Luca Carlo J. , Gilmore L. Donald
Published: October 2006

An electrode unit capable of detecting voluntarily elicited nerve signals for prolonged periods of time has been developed and tested. The electrode unit has been implanted around the distal ends of severed sciatic and peroneal nerves in rabbits. This electrode may prove suitable for implantation in human amputees for the purpose of recording neural control signals to activate prostheses with many degrees of freedom.
Attachment and Penetration of Miracidia Observed by Scanning Electron Microscopy
Authors: Blankespoor Harvey D. , van der Schalie Henry
Published: October 2006

Scanning electron microscopy can be utilized to understand more clearly many aspects of the parasite-host relationships of schistosome miracidia and their molluscan intermediate hosts. Specialized structures on the apical papilla of the miracicium, used for attachment and penetration, become visible in greater detail.
Russian Translation
Authors: O'Dette Ralph E.
Published: October 2006

This discussion has described the status of the large United States program for translation from the Russian. A partial description of what is being done or planned, and by whom, has been provided as a guide for those who wish to follow the subject further. The urge to pass on useful information has necessarily restricted the space which might also have been profitably devoted to the philosophic aspects of the problem.

Although it is not said with any sense of pride in achievement—because much more remains to be done than has been done—it would seem fair to describe the current national translation activity, including all contributions to it, as a phenomenon. Phenomena in scientific communication are not common: a full appreciation of their significance requires more analysis than results from a simple listing of their outward characteristics. But a few observations might be made in conclusion.

Most United States scientists probably feel that, as a nation, we are and should be world leaders in science, even though this feeling is neither nurtured nor expressed in a spirit of violent competition. If this assumption is allowed, the point which seems to remain is that the United States will not retain its position casually. Our scientists expect to maintain an awareness of the scientific achievements and failures of the other nations of the world. But we must especially become more aware of the advances of Soviet science, both qualitatively and quantitatively. The evidence points toward this last conclusion, regardless of whether one is concerned with the production of ideas or things, increase in man's knowledge of himself and his environment, conflict between idealisms, or simply the national security.
Origins and Status of American Botanists
Authors: Lyon Charles J.
Published: October 2006

The biographical data on botanists in the ninth edition of
American Men of Science
, supplemented by limited information from other sources, show a trend toward reduced numbers in the younger age groups, except for a continued increase in physiologists and a stabilized supply of pathologists. The 2640 botanists with bachelor's degrees from American colleges represent 401 undergraduate institutions, but more than half of them are alumni of a group of 37 large universities supported by public funds and 14 privately endowed colleges. More than 86 percent of the botanists have taken doctorates from 92 graduate schools, but 12 of the largest ones, located chiefly in the state universities, have provided two-thirds of these degrees; more than three-fourths of the candidates came from other colleges for their advanced training. Their fields of employment are predominantly in education and in government service, but appreciable numbers are doing research work for industry or in nonindustrial laboratories.
Radioactivity of People and Foods
Authors: Anderson Ernest C. , Schuch Robert L. , Langham Wright , Fisher William R.
Published: October 2006

Measurements of the cesium-137 content of people and of foodstuffs indicate that this nuclide is unlikely to be a decisive factor in the long-term hazards from weapons testing and reactor waste disposal. The amount of cesium-137 now present in the population of the United States averages 0.006 microcurie and shows no marked dependence on geographic location. The average radiation dose received from cesium-137 is one-twentieth of that received from natural radiopotassium and 1 percent of the average total dose from all natural sources. Because of the short biological half-life of cesium of about 140 days, it does not accumulate in the body as does strontium-90. The study of the distribution of cesium-137 is being continued to furnish information on the mechanisms of the fallout process and provide a measure of the rate of fallout and of stratospheric storage.
Proviral DNA of Moloney Leukemia Virus: Purification and Visualization
Authors: Gianni A. M. , Hutton J. R. , Smotkin D. , Weinberg R. A.
Published: October 2006

Closed-circular proviral DNA of Moloney leukemia virus has been purified from a 10
7
excess of cellular and mitochondrial DNA. The DNA can be visualized in the electron microscope and has the contour length of a molecule with a molecular weight of about 5.5 × 10
6
. Electron microscopic observation of a hybrid between viral RNA and this circular DNA confirms the viral origin of this molecule.
Coordinated Activities of Middle-Ear and Laryngeal Muscles in Echolocating Bats
Authors: Jen Philip H.-S. , Suga Nobuo
Published: October 2006

The middle-ear muscles and laryngeal muscles of the little brown bat (
Myotis lucifugus
) are highly developed. When the bat emits orientation sounds, action potentials of middle-ear muscles appear approximately 3 milliseconds after those of the laryngeal muscles; this activity of middle-ear muscles attenuates the vocal self-stimulation and improves the performance of the echolocation system. When an acoustic stimulus is delivered, both types of muscles contract; action potentials of the laryngeal muscles appear approximately 3 milliseconds after those of the middle-ear muscles. These two groups of muscles are apparently activated in a coordinated manner not only by the nerve impulses from the vocalization center, but also by those from the auditory system.
Neuroendocrine (Bag) Cells of
Aplysia
: Spike Blockade and a Mechanism for Potentiation
Authors: Dudek F. Edward , Blankenship James E.
Published: October 2006

Bag cell activity in
Aplysia
can be recorded intracellularly and extracellularly. Electrical stimulation anywhere along the connective nerves can produce prepotentials which are not synaptic potentials but represent the passive invasion of action potentials blocked in the neurites. Potentiation of these prepotentials results from progressive movement of the site of spike blockade toward the somata. This type of propagation plasticity may occur in many networks of low conduction safety.
Folic Acid Coenzymes
Authors: Huennekens F. M. , Osborn M. J. , Whiteley H. R.
Published: October 2006

The above reactions involving "active formyl" and "active hydroxymethyl" groups, their interconversion, their connections with free HCOOH and HCHO, and their interdigitation with methyl groups are diagrammed in Fig. 1.
Root Curvatures Induced by Culture Filtrates of
Aspergillus niger
Authors: Curtis Roy W.
Published: October 2006

Evidence obtained by paper chromatography indicates that corn root curvatures caused by culture filtrates of
Aspergillus niger
are caused by the same compound which causes curvatures and malformations on the stems and petioles of bean plants. The

R
f

values obtained for this compound were substantially different from those of indoleacetic acid.
Preservation of Whole Blood in Frozen State for Transfusion
Authors: Strumia Max M. , Colwell Louise C. , Strumia Paul V.
Published: October 2006

Addition of sugars to whole citrated human blood permits freezing and thawing with recovery of a large percentage of erythrocytes. Survival of erythrocytes thus frozen, transfused without further modification after thawing, has been satisfactory after 6 months of storage at –93°C.
Physicochemical Study in Water of a Mucoprotein with Virus-Inhibiting Activity
Authors: Maxfield Myles
Published: October 2006

Human urinary mucoprotein precipitated with cetyltrimethylammonium bromide and suspended in distilled water has a light-scattering molecular weight of 2.8 × 10
6
, an intrinsic viscosity of 225, a refractive index increment of 1.73 × 10
-4
, and an absorption coefficient (
E
1%
1 cm) of 11.4. The molecule is therefore smaller than that of the mucoprotein isolated by Tamm and Horsfall but retains its biological activity.
Demethylation of Chlorpromazine-(N-Methyl)-C
14
Authors: Ross John J. , Young Richard L. , Maass Alfred R.
Published: October 2006

Chlorpromazine methyl-C
14
was administered to three groups of rats—orally to one group following chronic oral administration of the unlabeled drug; orally to an unprimed group; and intravenously to another unprimed group. Appearance of C
14
O
2
in the air expired by all animals indicated that the rat metabolized the side chain of the labeled drug.