bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increase in Striatal [3H]Muscimol Binding Following Intrastriatal Injection of Kainic Acid: A Denervation Supersensitivity Phenomenon
Authors: Kuriyama Kinya , Kurihara Etsuo , Ito Yoshihisa , Yoneda Yukio 
Published: October 2006

AbstractThe effect of intrastriatal microinjection of kainic acid (KA) on specific binding of [3H]muscimol to the particulate fractions obtained from corpus striatum (CS), globus pallidus (GP), substantia nigra (SN), and cerebral cortex (CC) was examined. Seven days after the unilateral intrastriatal microinjection of KA, the amount of specifically bound [3H]muscimol was significantly increased at the injected site, whereas no significant alteration of [3H]muscimol binding was found in GP, SN, or CC. Scatchard analysis of striatal binding revealed that microinjection of KA significantly increased the affinity (KD) of GABA receptors on the injected (lesioned) side of the CS without affecting the total number of binding sites (Bmax) therein. This significant increase in [3H]muscimol binding, however, was eliminated by pretreating particulate fractions from the CS with Triton X‐100, a non‐ionic detergent. No statistically significant difference in amounts of [3H]muscimol binding was detected when the preparations from the KA‐treated and non‐treated CS were preincubated with 0.05% Triton X‐100, respectively. Scatchard analysis using CS preparations treated with 0.05% Triton X‐100 revealed that the affinity of the GABA receptor was increased by treatment with Triton X‐100, while the total number of binding sites (Bmax) was unchanged by this treatment. These results suggest that neuronal degeneration produced by KA in vivo and pretreatment of particulate preparations with Triton X‐100 in vitro may increase the amount of specifically bound [3H]muscimol to CS preparations by a similar molecular mechanism.
Degradation of Melanotropin Inhibiting Factor by Brain
Authors: Hui Koon‐Sea , Cheng Kwok‐Ping , Wong Ka‐Ho , Salschutz Michael , Lajtha Abel 
Published: October 2006

AbstractDegradation of melanotropin inhibiting factor (MIF) was measured by fluorometry, using pareptide as an internal standard, following the separation of the dansyl derivatives of MIF and its metabolites by HPLC. MIF was not split by carboxypeptidases A and B, prolidase, or pyroglutamate aminopeptidase. It was hydrolyzed by leucine aminopeptidase, aminopeptidase M, and carboxypeptidase Y. Rat brain hydrolyzed 159 nmol of MIF per mg of protein per h; the activity was linear with enzyme concentration. Hydrolysis starts from the N‐terminal end, as shown by the appearance of proline as the first metabolite of the MIF degradation, followed by leucine, glycinamide, leucylglycine, and glycine. Activity in the rat brain regions was in the order striatum, medulla oblongata > cortex, hippocampus, midbrain > hypothalamus, cerebellum, and pituitary. The enzyme was mostly in the supernatant, with significant amounts in the myelin and synaptosomal fractions. MIF aminopeptidase could be separated from carboxypeptidase by centrifugation at 30,000 ×g for 20 min and precipitation with 45‐75% (NH4)2SO4. It showed pH optima in the alkaline range (8.25 and 8.75) and was inhibited by EDTA, EGTA, SQ 14,225, puromycin, bacitracin, and bestatin.
Axonal Transport of the Molecular Forms of Acetylcholinesterase in Chick Sciatic Nerve
Authors: Couraud J. Y. , Giamberardino L. Di 
Published: October 2006

Abstract:Acetylcholinesterase (AChE) polymorphism was studied in the sciatic nerve of 4‐week‐old Leghorn chicks, by sucrose gradient sedimentation analysis. Four main AChE molecular forms were found with sedimentation coefficients of 5S, 7.5S, 11.5S and 20S respectively. Axonal transport of each of these forms was investigated on the basis of the enzyme accumulation kinetics measured on both sides of nerve transections and of the enzyme redistribution kinetics in nerve segments isolated in vivo. After nerve transection, 11.5S and 20S forms accumulated faster in the anterograde than in the retrograde direction and also much faster than 5S and 7.5S forms in the anterograde direction. Retrograde accumulations of 5S and 7.5S were faint or negligible. In addition, 1 h after nerve cutting, the accumulation rates for 11.5S and 20S forms (but not for 5S and 7.5S) fell, in both directions, to about one‐third of their initial values, probably owing to reversal of axonal transport at the axotomy site. Local protein synthesis inhibition by cycloheximide did not affect the accumulation of 11.5S and 20S in front of a transection, at least during the first hours, but reduced that of 5S and 7.5S by about 40%. In isolated nerve segments in vivo, the rapidly mobile fraction of AChE was estimated to constitute 23% of the total enzyme activity present in the nerve, 14% of it moving in an anterograde and 9% in a retrograde direction. A small amount of 11.5S molecules (approx. 20%) was in rapid transit (two‐thirds in the anterograde and one‐third in the retrograde direction), whereas almost all the 20S—about 90%—migrated rapidly (two‐thirds forwards and one‐third backwards). Anterograde velocities of 408 ± 94 and 411 ± 161 mm/day respectively were estimated for the 11.5S and 20S forms. Their respective retrograde velocities were 175 ± 85 and 145 ± 107 mm/day. Assuming that the totality of 5S and 7.5S molecules are moving in the anterograde direction, their accumulation rates were consistent with the average anterograde velocities of 2.9 ± 1.3 and 5.1 ± 1.4 mm/day, respectively. Couraud J. Y. and Di Giamberardino L. Axonal transport of the molecular forms of acetylcholinesterase in chick sciatic nerve. J. Neurochem. 35, 1053–1066 (1980).
Production and Purification of Antibody to Bovine White Matter Proteolipid Apoprotein
Authors: Macklin Wendy B. , Schwarting Gerald A. , Lees Marjorie B. , Cohen Steven R. 
Published: October 2006

Abstract:Circulating antibody to the bovine white matter proteolipid apoprotein was detected in rabbits 1 month after a single injection of the water‐soluble form of the apoprotein. By double immunodiffusion, the antiserum reacted specifically with the delipidated proteolipid apoprotein and the crude proteolipid fraction containing complex lipids; after exposure of the proteolipid apoprotein to sodium dodecyl sulfate (SDS), no reactivity was observed. The antiserum did not react with other myelin components, i.e., basic protein, cerebroside or GM1 ganglioside, nor was there reactivity with non‐neural proteolipids. The anti‐apoprotein antibody was purified by affinity chromatography. The antibody‐antigen interaction is apparently very hydrophobic, since elution of the antibody from the affinity column requires buffer containing 0.5% Triton X‐100‐4 M‐urea.
Desmethylimipramine Enhances the Release of Endogenous GABA and Other Neuro trans mitter Amino Acids from the Rat Thalamus
Authors: Korf Jakob , Venema Kor 
Published: October 2006

Abstract:The influence of desmethylimipramine (DMI) on the release of endogenous γ‐aminobutyric acid (GABA) and some other amino acids from the rat thalamus was studied with a push‐pull perfusion technique. Following HPLC the amino acids were fluorimetrically estimated. Added to the perfusion medium at a concentration of 10 μmol L‐1, DMI caused a 5‐ to 10‐fold increase in the release of GABA. Similar effects were found with imipramine, trimeprimine, haloperidol, and propranolol. The elevation of GABA release induced by DMI was Ca dependent. The release of aspartate and glutamate was also increased by DMI, but in contrast to K ions, DMI did not reduce the thalamic output of glutamine.
Characterization of [3H]Ouabain Binding Sites in Human Brain, Platelet, and Erythrocyte
Authors: Hauger R. , Luu H. M. D. , Goodwin F. K. , Paul S. M. 
Published: October 2006

Abstract:[3H]Ouabain binding was investigated in membranes prepared from human brain, erythrocyte, and platelet. Scatchard analysis of [3H]ouabain binding to human hypothalamic membranes revealed a single class of noninteracting binding sites with an apparent affinity constant (KD) of 21 nM. Though the number of [3H]ouabain binding sites was lower in human platelets than in erythrocytes, both tissues exhibited a single class of high‐affinity binding sites with an apparent KD similar to that found in human brain. Specific [3H]ouabain binding in basal ganglia tissue from patients with Huntington's disease was more than 50% lower than in tissue from age‐ and sex‐matched controls. These results, along with previous findings in rat brain, suggest that high‐affinity [3H]ouabain binding labels the neuronal form of Na,K‐ATPase in human brain, and may prove useful in quantitating this enzyme in postmortem brain samples.
Dopamine Inhibits Forskolin‐ and 3‐Isobutyl‐1‐Methylxanthine‐Induced Dark‐Adaptive Retinomotor Movements in Isolated Teleost Retinas
Authors: Dearry Allen , Burnside Beth 
Published: October 2006

Abstract:We have been investigating the mechanisms of diurnal and circadian regulation of teleost retinomotor movements. In the retinas of lower vertebrates, photoreceptors and melanin pigment granules of the retinal pigment epithelium (RPE) undergo movements at dawn and dusk. These movements continue to occur at subjective dawn and dusk in animals maintained in constant darkness. Cone myoids contract at dawn and elongate at dusk; RPE pigment disperses into the epithelial cells’ long apical processes at dawn and aggregates into the cell bodies at dusk. We report here that forskolin, an adenylate cyclase activator, and 3‐isobutyl‐1‐methylxanthine (IBMX), a phosphodiesterase inhibitor, each induces dark‐adaptive cone and RPE retinomotor movements in isolated light‐adapted green sunfish retinas cultured in constant light. Forskolin induces a 22‐fold elevation in retinal cyclic AMP content. Forskolin‐ and IBMX‐induced movements are inhibited approximately 65% and 95%, respectively, by 3,4‐dihydroxyphenylethylamine (dopamine). However, dopamine does not inhibit dark‐adaptive movements induced by dibutyryl cyclic AMP. Epinephrine is much less effective than dopamine in inhibiting forskolin‐induced movements, while phenylephrine and clonidine are totally ineffective. These results are consistent with our previous findings that treatments that increase intracellular cyclic AMP content promote darkadaptive retinomotor movement. They further suggest that dopamine inhibits adenylate cyclase activity in photoreceptors and RPE cells and thereby favors light‐adaptive retinomotor movements.
Digitonin‐Permeabilized Cells Are Exocytosis Competent
Authors: Schäfer Theo , Karli Urs O. , Gratwohl Eugen K.‐M. , Schweizer Felix E. , Burger Max M. 
Published: October 2006

Abstract:Release of norepinephrine from PC12 cells can be stimulated by free Ca2+ in micromolar concentrations after permeabilization with 10 μg/ml of digitonin. This release is time and temperature dependent, half‐maximal at 0.3 μM Ca2+, and, after washing out of endogenous ATP, half‐ maximal at about 0.5 mA/ MgATP when exogenously added. Similar results were obtained with bovine adrenal chromaffin cells using the same protocol. Support for the idea that the mechanism of release from both permeabilized cell types is still exocytosis is demonstrated at the electron microscopic level by immunolabeling chromaffin granule membrane antigens that were introduced into the plasma membrane following stimulation. Electron micrographs furthermore demonstrate that chromaffin granules retain typical dense cores after permeabilization, indicating that leakiness of catecholamines from the granules was not major factor. Pores, formed by digitonin in the plasma membranes, were utilized to introduce antibodies into such exocytosis‐competent cells. Anti‐actin and anti‐chromaffin granule membrane antibodies show a staining pattern similar to conventionally fixed and stained preparations. Our results demonstrate that pores formed by digitonin do not impair the process of exocytosis although they are big enough to allow macromolecules to pass in both directions. The digitonin‐permeabilized cell is therefore an ideal in vitro system with which to study the fusion process between chromaffin granules and the plasma membrane.
Characterization of Neurotensin Binding Sites in Intact and Solubilized Bovine Brain Membranes
Authors: Mills A. , Demoliou‐Mason C. D. , Barnard E. A. 
Published: October 2006

AbstractAnalysis of the equilibrium binding of [3H]‐neurotensin(1–13) at 25°C to its receptor sites in bovine cortex membranes indicated a single population of sites with an apparent equilibrium dissociation constant (KD) of 3.3 nM and a density (Bmax) of 350 fmol/mg protein (Hill coefficient nH= 0.97). Kinetic dissociation studies revealed the presence of a second class of sites comprising <10% of the total. KD values of 0.3 and 2.0 nM were obtained for the higher and lower affinity classes of sites, respectively, from association‐dissociation kinetic studies. The binding of [3H]neurotensin was decreased by cations (monovalent and divalent) and by a nonhydrolysable guanine nucleotide analogue. Competition studies gave a potency ranking of [Gln4]neurotensin > neurotensin(8–13) > neurotensin(1–13). Smaller neurotensin analogues and neurotensin‐like peptides were unable to compete with [3H]neurotensin. Stable binding activity for [3H]neurotensin in detergent solution (KD= 5.5 nM, Bmax= 250 fmol/mg protein, nH= 1.0) was obtained in 2% digitonin/l mM Mg2+ extracts of membranes which had been preincubated (25°C, 1 h) with 1 mM Mg2+ prior to solubilization. Association‐dissociation kinetic studies then revealed the presence of two classes of sites (KD1= 0.5 nM, KD2= 3.6 nM) in a similar proportion to that found in the membranes. The solubilized [3H]‐neurotensin activity retained its sensitivity to cations and guanine nucleotide.
Antiproliferative Action of Benzodiazepines in Cultured Brain Cells Is Not Mediated Through the Peripheral‐Type Benzodiazepine Acceptor
Authors: Gorman Adrienne M. C. , O'Beirne Gerard B. , Regan Ciaran M. , Williams D. Clive 
Published: October 2006

AbstractThe benzodiazepines, Ro 5–4864, diazepam, clonazepam, and also PK‐11195, inhibited, at micromolar concentrations, the proliferation of rat C6 glioma and mouse neuro‐2A neuroblastoma cells in culture. The cells possessed high levels of “peripheral‐type” high‐affinity benzodiazepine binding sites as judged by binding assays and displacement potencies. However, the different potencies and specificities of compounds for the antiproliferative actions and binding affinities for the binding site suggest that the antiproliferative actions were not mediated through the peripheral‐type binding site. In support of this, these compounds have also been shown to inhibit proliferation of some nonneuronal cultured cell lines, e.g., mouse SP2/0‐Agl4 hybridoma and rat NCTC epithelial cells, which have no detectable high‐affinity peripheral‐type benzodiazepine binding sites.
Regulation of Cyclic AMP Formation in Cultures of Human Foetal Astrocytes by β2‐Adrenergic and Adenosine Receptors
Authors: Woods Mary D. , Ian Freshney R. , Ball Stephen G. , Vaughan Peter F. T. 
Published: October 2006

AbstractTwo cell cultures, NEP2 and NEM2, isolated from human foetal brain have been maintained through several passages and found to express some properties of astrocytes. Both cell cultures contain adenylate cyclase stimulated by catecholamines with a potency order of isoprenaline > adrenaline > salbutamol < noradrenaline, which is consistent with the presence of β2‐adrenergic receptors. This study reports that the β2‐adrenergic‐selective antagonist ICI 118,551 is ˜ 1,000 times more potent at inhibiting isoprenaline stimulation of cyclic AMP (cAMP) formation in both NEP2 and NEM2 than the β1adrenergic‐selective antagonist practolol. This observation confirms the presence of β2‐adrenergic receptors in these cell cultures. The formation of cAMP in NEP2 is also stimulated by 5′‐(N‐ethylcarboxamido)adenosine (NECA) more potently than by either adenosine or N6‐(L‐phenylisopropyl)adenosine (L‐PIA), which suggests that this foetal astrocyte expresses adenosine A2 receptors. Further more, L‐PIA and NECA inhibit isoprenaline stimulation of cAMP formation, a result suggesting the presence of adenosine A1 receptors on NEP2. The presence of A1 receptors is confirmed by the observation that the A1‐selective antagonist 8‐cyclopentyl‐1,3‐dipropylxanthine reverses the inhibition of isoprenaline stimulation of cAMP formation by L‐PIA and NECA. Additional evidence that NEP2 expresses adenosine receptors linked to the adenylate cyclase‐inhibitory GTP‐binding protein is provided by the finding that pretreatment of these cells with pertussis toxin reverses the adenosine inhibition of cAMP formation stimulated by either isoprenaline or forskolin.
Peptidasic Activities Associated with Acetylcholinesterase Are Due to Contaminating Enzymes
Authors: Checler Frédéric , Vincent Jean‐Pierre 
Published: October 2006

AbstractThe esterasic and peptidasic activities of two different sources of acetylcholinesterase purified from electric eel were examined. Hydrolyses of leucine‐enkephalin and neurotensin indicated that both sources exhibited exopepti‐dasic and tryptic‐like activities. However, the enzyme preparation which appeared 10‐fold enriched with regard to the esterasic activity was found to display a 50‐ and 185‐fold lower tryptic‐like and exopeptidasic function, respectively. This lack of parallelism in the enrichment of the various activities seemed to indicate that they were not co‐purified. Immunoprecipitation experiments performed with monoclonal antibodies directed towards the catalytic subunit of globular or asymmetric forms of electric eel acetylcholinesterase allowed the physical dissociation of esterasic and peptidasic functions and therefore confirmed that the ability of acetylcholinesterase to hydrolyze various neuropeptides was likely due to contaminating peptidases.
Circadian Regulation of Melatonin in the Retina of Xenopus laevis: Limitation by Serotonin Availability
Authors: Cahill Gregory M. , Besharse Joseph C. 
Published: October 2006

Abstract:Treatments expected to increase retinal serotonin levels were found to stimulate melatonin production by cultured eyecups from Xenopus laevis. The monoamine oxidase inhibitor pargyline (100 μM) caused a sixfold increase in melatonin release, and the serotonin precursor 5‐hydroxy‐L‐tryptophan (100 μM) caused a 70‐fold increase. Both acted synergistically with eserine, an inhibitor of melatonin deacetylation in the retina. The effect of 5‐hydroxytryptophan was dose dependent, with effects increasing from 1 to 100 μM. Increasing the tryptophan level in the culture medium had no effect on melatonin release. These results indicate that the rate‐limiting step in retinal melatonin synthesis is 5‐hydroxylation of tryptophan. Melatonin released from individual eyecups in superfusion culture in constant darkness with and without added 5‐hydroxy‐L‐tryptophan was monitored over a 5‐day period. Control eyecups released low levels of melatonin, with circadian rhythmicity persisting for 1–3 days. With 5‐hydroxy‐L‐tryptophan added, melatonin levels were elevated 10–20‐fold at all times, and rhythmicity was apparent for as long as five cycles. This provides a model system for studies of the circadian clock in the eye.
Stability and Absorption Spectrum of Malononitrile
Authors: Mendelson J. , Mendelson J. H. , Fax B. J. , Grenell R. G. 
Published: October 2006

1) Spectra in the ultraviolet and visible regions have been obtained on samples of malononitrile under different conditions. The samples were manufactured by several companies in America and Sweden.
2) The spectral analysis has demonstrated that the compound used by Hydén and Hartelius is not the same as that employed by American investigators. If, however, an aqueous solution of the American product is allowed to stand at room temperature for a long enough time, it develops the same spectral characteristics as the Swedish solution.
3) Future studies will concern themselves with attempts to identify, the active substance and to examine its effect on neuronal nucleoproteins.
Meaning, Memory Structure, and Mental Processes
Authors: Meyer David E. , Schvaneveldt Roger W. 
Published: October 2006

Although people experience little difficulty in recognizing printed words and comprehending sentences, they cannot do it instantaneously. Experimental psychologists have recently measured the speed of these mental processes by applying a reaction-time method. The method provides new data concerning the organization and retrieval of familiar semantic information in human memory.
It has been found that close relations between the meanings of words help people to recognize and pronounce the words faster, especially when the words are hard to see because of visual distortions. Close relations between word meanings also facilitate the comprehension of some sentences, as indicated by how long a person takes to decide whether the sentences are true or false. The facilitation is not universal, however. When the relation between the meanings of two words must be analyzed carefully, their proximity may actually inhibit mental processing.
These results, along with additional findings, support the hypothesis that human memory includes a semantic network that represents various categories of objects at distinct locations linked to specify their relations with each other. The memory structure probably influences a number of different mental processes that use it. One possible access route to the network is through a set of detectors designed to accumulate sensory information and signal the presence of particular words. There also appear to be processes for searching and comparing pieces of knowledge after a person finds the memory locations of designated categories. Further research using the reaction-time method may provide a more detailed inventory of what facts are retrieved directly from memory and what are computed from other stored information .
Infectious Nucleic Acids, a New Dimension in Virology
Authors: Herriott Roger M. 
Published: October 2006

Viral nucleic acids have been found to be infectious for tissues and animals, yet are nonantigenic and resistant to antibodies against whole virus. Other unique properties, such as their host range and their susceptibility to nuclease action, render them a wholly new dimension to be reckoned with in virology.
These properties may explain a number of conditions which at present are considered anomalous. The release from infected tissues of even a small proportion of total virus as free nucleic acid could, in an otherwise immune individual, lead to a low level of infection which would, perhaps, explain permanent immunity. If the proportion of nucleic acid is higher, or if the nucleic acid is resistant to nucleases because of an inert envelope, such conditions as "carrier" states—that is, viremias with or without antibodies—are possible.

Note added in proof:
The recent article by J. D. Ebert and F. H. Wilt came to my attention after the present article was written. Ebert and Wilt's excellent article indicates the impact of the newer knowledge of viral nucleic acids on the ideas developing in the field of embryology.