bluuebunny/crossref_metadata_2025 huggingface dataset:
Reexamination of the Crystal Structure of Na3Sb7O9Se3·Sb0.319(H2O,OH)3
Authors: Miyawaki Ritsuro , Nakai Izumi , Nagashima Kozo
Published: August 2006

The crystal structure of Na3Sb7O9Se3·Sb0.319(H2O,OH)3 has been determined using a single crystal prepared by hydrothermal synthesis to a conventional R = 0.043, Rw = 0.039 for 1556 reflections. It is hexagonal with a space group of P63; a = 14.422(4), c = 5.5448(8) Å, Z = 2. The structure consists of infinite tunnels formed by the linkages of SbO3 pyramids. SbSe3 pyramids among the tunnels connect the tunnels to form a three-dimensional structure. Na atoms were on the inside wall of the tunnel. It was revealed that statistically occupied Sb(H2O,OH)6-octahedra are located at the center of the tunnel. Two statistical sites for the Sb atom of the SbSe3 pyramids are pointed out.
Molar Volume Effect of Pyridylazophenols and Their Metal Chelates on Their Distribution between Aqueous Micellar Pseudophases in Triton X-100 Micellar Solutions
Authors: Saitoh Tohru , Segawa Haruki , Kamidate Tamio , Watanabe Hiroto , Haraguchi Kensaku
Published: August 2006

The distribution constants of 2-(2-pyridylazo)phenol (PAP), 2-(2-pyridylazo)-5-methylphenol (PAP-5Me), and metal chelates with PAP and PAP-5Me between aqueous micellar psuedophases were evaluated in aqueous micellar solutions of Triton X-100. The distribution constants were found by measurement of equilibrium shifts in acid-base and complexation reactions in the presence of micelles at an ionic strength of 0.1 ((Na+, H+) ClO4−) and at 293 ± 1 K. The metal chelates (vanadium(V), nickel(II), and iron(II)) had a linear correlation between their logarithmic distribution constants and their van der Waals volumes. PAP and PAP-5Me had a different kind of correlation from the metal chelates did. These results were explained by the difference in the part of the micelles into which hydrophobic chelates and hydrophilic chelating reagents were incorporated.
Study of the Adsorption Layer at the Glass-Dye Solution Interface by Variable Incidence-Angle Internal-Reflection Spectrometry
Authors: Hinoue Teruo , Imamura Goro , Yokoyama Yu
Published: August 2006

The reflectivity was measured at the interface between the glass substrate and the Brilliant Blue (BB) or Methylene Blue (MB) aqueous solution as a function of the angle of incidence at 632.8 nm from a He–Ne laser. The relationship between the reflectivity and the angle of incidence was analyzed by an approximate expression derived from the basic theory of internal reflection spectroscopy. On the other hand, a plot of the reflectivity against the effective thickness was used as a ready diagnosis of the dye adsorbed by the glass substrate. From the results it has been suggested that BB is not adsorbed, whereas MB is. Based on a parameter obtained experimentally, the thickness of the adsorption layer was determined to be 0.65 ± 0.18 nm. This result suggests that the MB cation is adsorbed parallel to the glass surface to form a monomolecular layer. Further, it has been revealed from a similar analysis that the addition of a cationic surfactant with a long alkyl chain in the MB solution prevents the adsorption of MB by the glass substrate, whereas the addition of an anionic surfactant with a long alkyl chain promotes adsorption.
Synthesis of Some New Thieno[2,3-b][1,6]naphthyridines and Related Compounds
Authors: Geies A A , Abdel-Hafez A A , Lancelot J C , El-Kashef H S
Published: August 2006

3,5-Dibenzylidene-1-isopropy1-4-piperidinone (1) reacts with cyanothioacetamide to give 1,6-naphthyridine-2(1H) thione derivative 2. Reaction of 2 with halo ketones or halo esters followed by ring closure gives thieno[2,3-b][1,6]naphthyridine derivatives 5a—i, which are used as versatile intermediates in the synthesis of related heterocyclic ring systems as pyrimidothienonaphthyridines 10, 11, 14, and 15, oxazinothienonaphthyridine (13) and triazinothienonaphthyridine (9).
Photoinduced Electron-Transfer Reactions of Arylmethyl-Substituted 14 Group Compounds: Photoarylmethylation and Photooxygenation
Authors: Tamai Toshiyuki , Mizuno Kazuhiko , Hashida Isao , Otsuji Yoshio
Published: August 2006

Photoreactions of arylmethylsilanes, -germane, and -stannane with 1,4-dicyanonaphthalene (DCN) and 9,10-dicyanoanthracene (DCA) were studied under various conditions. The arylmethylation of DCN and DCA occurred in the photoreaction under nitrogen atmosphere, whereas the oxygenation of the arylmethyl organometallic compounds occurred in the photoreaction under oxygen atmosphere. Key intermediates in these reactions in acetonitrile were radical ions which were generated via photoinduced electron transfer from the arylmethyl organometallic compounds to the excited singlet of DCN or DCA. The cleavage of the carbon–metal bond of the radical cations of the arylmethyl compounds resulted in the formation of arylmethyl radicals. The radicals reacted then with the radical anions of DCN and DCA to produce the arylmethylated compounds or reacted with oxygen to produce the oxygenated compounds. The efficiency of the photoreactions was affected by solvents and added materials to the reaction systems. In the photoreactions in benzene, the exciplexes of the type 1[A–ArCH2MR3]* or the triplexes of the type [A–C6H6–ArCH2MR3]* (A = DCN, DCA) were involved as intermediates. The reactivity features of the photoreactions are discussed.
Synthesis of (−)-Conduritol F, (+)-Conduritol B, Cyclophellitol from l-Quebrachitol
Authors: Akiyama Takahiko , Shima Hiroaki , Ohnari Masatoshi , Okazaki Tadashi , Ozaki Shoichiro
Published: August 2006

The methyl ether of cyclitols with vicinal hydroxyl group was cleaved chemoselectively in preference to both cis- and trans-cyclohexylidene moieties by AlCl3–n-Bu4NI to afford parent alcohols in good yields. (−)-Conduritol F was prepared from l-quebrachitol, an optically active cyclitol from the serum of rubber trees, in five steps by use of the demethylation reaction. The first chiral synthesis of (+)-conduritol B and the total synthesis of cyclophellitol, a novel β-glucosidase inhibitor, are described.
Binding Properties of p-(Phenylazo)calixarenes for Metal Ions
Authors: Nomura Eisaku , Taniguchi Hisaji , Otsuji Yoshio
Published: August 2006

The binding properties of p-(phenylazo)calix[n]arenes (n = 6 and n = 4) for metal ions have been studied. The calixarenes show a highly selective binding ability toward Ag+, Hg+, and Hg2+. This property can be explained in terms of a metal ion-induced azo/hydrazone tautomerism. The Ag+ ion forms complexes with the azocalixarenes by binding with their hydrazone tautomers.
X-Ray Crystallographic Studies of Vitamin E Derivatives. Relationship between Antioxidant Activity and Molecular Structure
Authors: Mukai Kazuo , Ohbayashi Shigeru , Nagaoka Shin-ichi , Ozawa Takehiro , Azuma Nagao
Published: August 2006

Molecular structures of vitamin E derivatives were analyzed with X-ray diffraction. The relationship between the antioxidant activity and the molecular structure of vitamin E is discussed.
Evidence for the Role of Monovalent Copper Ions in the Photocatalytic N2O Decomposition on Excessively Copper Ion-Containing ZSM-5 Zeolite
Authors: Ebitani Kohki , Morokuma Munehiro , Kim Jong-Ho , Morikawa Akira
Published: August 2006

The activity of the photocatalytic N2O decomposition into N2 and O2 on a degassed Cu-containing ZSM-5 zeolite (percent exchange, 145%) corresponded well to the amount of monovalent copper (Cu+) present on the Cu/ZSM-5, which was titrated by the irreversibly adsorbed CO at 273 K.
Dehydrochlorination of Copoly(styrene/2-chloromaleic anhydride)
Authors: Ogawa Naotake , Taguchi Hiroyuki , Sato Takatoshi
Published: August 2006

2-Chloromaleic anhydride and styrene were copolymerized by solution polymerization. The copoly(styrene/2-chloromaleic anhydride) was dehydrochlorinated by heating under reduced pressure and a polymer having a structure similar to the maleic anhydride moiety in the polymer chain was obtained. The dehydrochlorination was completed by heating at 220 °C for 1 h.
Synthesis and Antiinflammatory Activity of Some 1,4-Dihydro-3-methyl-1-(2-thiazolyl)pyrazolo[4,3-c][1,2]benzothiazine 5,5-Dioxides
Authors: Sharma Pawan K , Sawhney Shanti N
Published: August 2006

Condensation of 1,4-dihydro-3-methyl-1-thiocarbamoylpyrazolo[4,3-c][1,2]benzothiazine 5,5-dioxide with various phenacyl bromides, ethyl 3-aroyl-3-bromopropionates, and ethyl bromopyruvate afforded 1,4-dihydro-3-methyl-1-(2-thiazolyl)pyrazolo[4,3-c][1,2]benzothiazine-5,5 dioxides, which were also prepared by an alternate route in order to confirm their structure, were tested for antiinflammatory activity by carrageenan-induced rat paw edema test. The compounds have shown moderate to good activity.
Sequence-specific RNA binding mediated by the RNase PH domain of components of the exosome
Authors: Anderson John R. , Mukherjee Devi , Muthukumaraswamy Karthika , Moraes Karen C.M. , Wilusz Carol J. , Wilusz Jeffrey
Published: August 2006

We have previously demonstrated that PM-Scl-75, a component of the human exosome complex involved in RNA maturation and mRNA decay, can specifically interact with RNAs containing an AU-rich instability element. Through the analysis of a series of deletion mutants, we have now shown that a 266 amino acid fragment representing the RNase PH domain is responsible for the sequence-specific binding to AU-rich elements. Furthermore, we found that the RNase PH domains from two other exosomal components, OIP2 and RRP41, as well as from Escherichia coli polynucleotide phosphorylase, are all capable of specifically interacting with RNAs containing an AU-rich element with similar affinities. Finally, we demonstrate that the interaction of the RNase PH domain of PM-Scl-75 is readily competed by poly(U), but only inefficiently using other homopolymeric RNAs. These data demonstrate that RNase PH domains in general have an affinity for U- and AU-rich sequences, and broaden the potential role in RNA biology of proteins containing these domains.
Secondary Hyperparathyroidism in Chronic Kidney Disease: Focus on Clinical Consequences and Vitamin D Therapies
Authors: Hudson Joanna Q
Published: August 2006

Objective:

To assess vitamin D–based treatment approaches for secondary hyperparathyroidism and its complications.

Data Sources:

A literature search was performed using MEDLINE (1990–February 28, 2006). Key words used were chronic kidney disease and vitamin D to identify relevant papers published in English.

Study Selection and Data Extraction:

From the database of articles generated, 48 papers were identified. Titles and abstracts were examined to identify those directly related to the objective. Discussion was expanded through the bibliographies of cited articles.

Data Synthesis:

The increasing prevalence of chronic kidney disease (CKD) in the US indicates an urgent need for treatment strategies to delay or prevent disease progression. Abnormalities in phosphorus and calcium homeostasis, vitamin D levels, and the subsequent development of secondary hyperparathyroidism (SHPT) are secondary complications of CKD associated with increased morbidity and mortality. Management options include dietary phosphorus restriction, phosphate binders and/or calcium supplementation, vitamin D supplementation, and calcimimetics. Vitamin D supplementation has received increased attention given the prevalence of vitamin D deficiency in patients with CKD and the beneficial effect of correcting this deficiency.

Conclusions:

Early identification and intervention appropriate to the stage of CKD are likely to improve patient outcomes. Improved knowledge of interactions between vitamin D and vitamin D receptors has led to the development of vitamin D analogs and calcimimetics, which offer benefits in the management of SHPT. Integrating available treatment options into practice to achieve optimal therapeutic goals of SHPT based on the stage of CKD is a significant challenge for pharmacists managing patients with CKD.
Paradoxically Decreased HDL-Cholesterol Levels Associated with Rosiglitazone Therapy
Authors: Gutschi L Maria , Malcolm Janine C , Favreau Colette M , Ooi Teik Chye
Published: August 2006

Objective:

To report 2 cases of very low high-density lipoprotein cholesterol (HDL-C) levels associated with rosiglitazone therapy.

Case Summary:

Two patients with type 2 diabetes taking rosiglitazone for glycemic control developed paradoxically low HDL-C levels during rosiglitazone therapy. In the first patient, the HDL-C level decreased from 33 to 11.6 mg/dL after 8 months of therapy. The second patient's HDL-C level decreased from the baseline level of 44.8 mg/dL to 19.7 mg/dL after 4 months of rosiglitazone use. These abnormalities resolved on discontinuation of rosiglitazone and were not observed when the patients were treated with pioglitazone. The patients had no changes to other drug therapy or medical conditions known to affect lipid metabolism during treatment with rosiglitazone.

Discussion:

Thiazolidinediones, insulin sensitizers widely used in the treatment of type 2 diabetes, have been reported to have beneficial effects on lipids, such as triglyceride lowering and HDL-C elevation, in addition to their glucose-lowering effects. It has been suggested that rosiglitazone and pioglitazone, the 2 currently available thiazolidinediones, may differ in their effects on lipids. As of July 2006, a total of 8 cases of paradoxical lowering of plasma HDL-C associated with rosiglitazone have now been reported. Based on use of the Naranjo probability scale, the 2 cases presented here were probably associated with rosiglitazone. The duration of therapy may be important in this paradoxical effect.

Conclusions:

Rosiglitazone is associated with a paradoxical decrease in HDL-C levels in patients with type 2 diabetes. In patients receiving rosiglitazone, a baseline lipid panel should be performed and lipid values should be monitored during the course of therapy.
Stepwise synthesis of chitooligosaccharides through a transition-state analogue substrate catalyzed by mutants of chitinase A1 from Bacillus circulans WL-12
Authors: Kohri Michinari , Kobayashi Atsushi , Noguchi Masato , Kawaida Shin-ichi , Watanabe Takeshi , Shoda Shin-ichiro
Published: August 2006

Several mutants of chitinase A1 fromBacillus circulansWL-12 have been prepared by site-directed mutagenesis of tryptophan 433. The hydrolytic activity of these mutants towardp-nitrophenyl chitobioside was lower than that of wild-type chitinase A1. The mutants were found to catalyze the transglycosylation reaction of the 1,2-oxazoline derivative ofN-acetyllactosamine (Gal-GlcNAc-oxa) toN,N′′-diacetylchitobiose (GlcNAc-GlcNAc), giving rise to a transglycosylated tetrasaccharide product (Gal-GlcNAc-GlcNAc-GlcNAc) in high yield. Based on these results, a one-pot synthesis of chitooligosaccharides by combined use of mutant W433Y and β-galactosidase has been demonstrated. By controlling the reaction conditions, chitotriose and chitotetraose were obtained in 74% and 40% yield (determined by HPLC), respectively, without isolating any intermediate products.
Wood liquefaction by ionic liquids
Authors: Honglu Xie , Tiejun Shi
Published: August 2006

The liquefaction of wood (Metasequoia glyptostroboides) has been studied in two imidazole-based ionic liquids: IL1, 3,3′-ethane-1,2-diylbis(1-methyl-1H-imidazol-3-ium) dichloride; and IL2, 3,3′-ethane-1,2-diylbis(1-methyl-1H-imidazol-3-ium) dichloroaluminate. Rapid and complete liquefaction was obtained in IL2 without residue at 120°C for 25 min, in contrast to liquefaction in phenol/H2SO4 (liquid/wood ratio 20:1) with 25.9% residue. Temperature- and time-dependent studies indicate that the performance of the reagents investigated is IL2>IL1> phenol/H2SO4. The liquid/wood ratio and the amount of AlCl3 as catalyst affect the liquefaction rate. In the course of liquefaction with IL2, AlCl3 plays a dual role as a catalyst and a liquefaction reagent. Ionic liquids separated from the liquefied product can be recycled at least five times to maintain a good liquefaction rate.
Phenolic compounds in silver birch (Betula pendula Roth) wood
Authors: Hiltunen Eveliina , Pakkanen Tuula T. , Alvila Leila
Published: August 2006

Three new phenolic compounds (4-hydroxy-2-methoxyphenyl-6-O-syringoyl-β-D-glucopyranoside, 2-hydroxy-4-methoxyphenyl-6-O-syringoyl-β-D-glucopyranoside, and 4-hydroxymethyl-2-methoxyphenyl-6-O-syringoyl-β-D-glucopyranoside) and 15 known phenolic compounds (two phenyl glucoside esters, five lignans, three diarylheptanoids and five simple aldehydes or ketones) were isolated from the secondary xylem of mature Betula pendula Roth. The compounds were identified on the basis of their NMR (1D and 2D) and mass spectral data. In total, 23 phenolic extractives present in the sapwood of two winter-dormant B. pendula trees felled at different growing sites (rich in nutrients and scarce in nutrients) were quantified by GC. Their amounts were mostly low, 0.01–0.18 mg g−1 of dry wood. Total amounts of the phenolic extractives isolated were 1.2 mg g−1 of dry wood (5.6% of the total methanol-soluble extractives) in the tree felled at the site rich in nutrients, and 1.9 mg g–1 of dry wood (10% of the total methanol-soluble extractives) in the tree felled at the site scarce in nutrients.
Analysis of fragrance compositions of precious coniferous woods grown in Taiwan
Authors: Wang Sheng-Yang , Wang Yen-Shung , Tseng Yen-Hsueh , Lin Chien-Tsong , Liu Chiung-Pin
Published: August 2006

Odor is one of the most distinctive characteristics of wood. Woods in the family Taxodiaceae and Cupressaceae often emit fragrant odors. In this study, the fragrance compounds of six coniferous woods grown in Taiwan, namely Chamaecyparis formosensis, Chamaecyparis obtusa var. formosana, Calocedrus macrolepis var. formosana, Taiwania cryptomerioides, Cunninghamia lanceolata, and Cryptomeria japonica, were studied by solid-phase microextraction and GC/MS. A non-biased overall profile of the fragrance compositions of the woods was obtained. The major aroma compounds were: β-elemene (15.8%), γ-cadinene (12.1%), α-pinene (11.1%), and limonene (10.8%) in C. obtusa; myrtenol (27.0%), myrtenyl (19.2%), and γ-cadinene (11.4%) in C. formosensis; β-cedrene (22.3%), δ-cadinene (17.6%), and widdrene (11.4%) in T. cryptomerioides; β-cedrene (26.2%) α-pinene (19.7%) and limonene (13.2%) in C. lanceolata; 3-carene (21.0%), p-cymene (11.0%), and limonene (9.5%) in C. japonica; and p-cymene (24.4%), terpinen-4-ol (16.6%), and α-terpineol (12.5%) in C. macrolepis. The results may provide useful information for future studies on chemotaxonomy and metabolomics of conifers.
A simple anisotropy correction procedure for acoustic wood tomography
Authors: Maurer Hansruedi , Schubert Sandy Isabelle , Bächle Fritz , Clauss Sebastian , Gsell Daniel , Dual Jürg , Niemz Peter
Published: August 2006

Anisotropy of acoustic propagation velocities is a ubiquitous feature of wood. This needs to be considered for successful application of travel time tomography, an increasingly popular technique for non-destructive testing of living trees. We have developed a simple correction scheme that removes first-order anisotropy effects. The corrected travel-time data can be inverted with isotropic inversion codes that are commercially available. Using a numerical experiment, we demonstrate the consequences of ignoring anisotropy effects and outline the performance of our correction scheme. The new technique has been applied to two spruce samples. Subsequent inspection of the samples revealed a good match with the tomograms.
Electrical Coupling between Locomotor-Related Excitatory Interneurons in the Mammalian Spinal Cord
Authors: Hinckley Christopher A. , Ziskind-Conhaim Lea
Published: August 2006

Locomotor rhythm generation is a fundamental characteristic of neural networks in the spinal cord. Identifying the synaptic interactions between neurons in the locomotor circuitry is key to our understanding of the mechanisms that underlie the production of rhythmic motor outputs. Using transgenic mice in which the homeobox geneHB9drives the reporter green fluorescent protein (GFP), we have demonstrated that a genetically distinct cluster of Hb9/GFP-expressing interneurons (Hb9 INs) can generate locomotor-like rhythms in the newborn mouse spinal cord (Hinckley et al., 2005b). Processes of Hb9 INs are in close apposition to adjacent Hb9 INs, raising the possibility that the interneurons are synaptically interconnected. To test this hypothesis, whole-cell paired recordings were performed from visually identified Hb9 INs. High-incidence bidirectional electrical coupling was evident between Hb9 INs in spinal cords of newborn and juvenile mice. The coupling strength varied from 2 to 32% with an average of 12%. Our data suggested that the variability was not correlated with the distribution of electrical synapses at different electronic distances. Electrical synapses behaved as low-pass filters, reducing currents passing at frequencies >3 Hz. Episodes of spontaneous bursts of EPSCs were synchronous in coupled Hb9 INs, indicating that common synaptic inputs coordinated their activity. However, non-NMDA receptor-mediated synaptic transmission was not required to synchronize neurochemically induced membrane oscillations between electrically coupled interneurons. The finding that electrical transmission persists in mice that can walk is indicative of its importance in coordinating the activity of this neuronal population in functionally mature spinal networks.
Transient Functional Suppression and Facilitation of Japanese Ideogram Writing Induced by Repetitive Transcranial Magnetic Stimulation of Posterior Inferior Temporal Cortex
Authors: Ueki Yoshino , Mima Tatsuya , Nakamura Kimihiro , Oga Tatsuhide , Shibasaki Hiroshi , Nagamine Takashi , Fukuyama Hidenao
Published: August 2006

The Japanese writing system is unique in that it is composed of two different orthographies: kanji (morphograms) and kana (syllabograms). The retrieval of the visual orthographic representations of Japanese kanji is crucial to the process of writing in Japanese. We used low-frequency repetitive transcranial magnetic stimulation (rTMS) to clarify the functional relevance of the left and right posterior inferior temporal cortex (PITC) to this process in native Japanese speakers. The experimental paradigms included the mental recall of kanji, kana-to-kanji transcription, semantic judgment, oral reading, and copying of kana and kanji. The first two tasks require the visualization of the kanji image of the word. We applied 0.9 Hz rTMS (600 total pulses) over individually determined left or right PITC to suppress cortical activity and measured subsequent task performance. In the mental recall of kanji and kana-to-kanji transcription, rTMS over the left PITC prolonged reaction times (RTs), whereas rTMS over the right PITC reduced RTs. In the other tasks, which do not involve the mental visualization of kanji, rTMS over the left or right PITC had no effect on performance. These results suggest that the left PITC is crucial for the retrieval of the visual graphic representation of kanji. Furthermore, the right PITC may work to suppress the dominant left PITC in the neural network for kanji writing, which involves visual word recognition.
Aberrant GABAAReceptor Expression in the Dentate Gyrus of the Epileptic Mutant Mouse Stargazer
Authors: Payne Helen L. , Donoghue Peter S. , Connelly William M. K. , Hinterreiter Sabine , Tiwari Priyanka , Ives Jane H. , Hann Victoria , Sieghart Werner , Lees George , Thompson Christopher L.
Published: August 2006

Stargazer (stg) mutant mice fail to express stargazin [transmembrane AMPA receptor regulatory protein γ2 (TARPγ2)] and consequently experience absence seizure-like thalamocortical spike-wave discharges that pervade the hippocampal formation via the dentate gyrus (DG). As in other seizure models, the dentate granule cells ofstgdevelop elaborate reentrant axon collaterals and transiently overexpress brain-derived neurotrophic factor. We investigated whether GABAergic parameters were affected by thestgmutation in this brain region. GABAAreceptor (GABAR) α4 and β3 subunits were consistently upregulated, GABAR δ expression appeared to be variably reduced, whereas GABAR α1, β2, and γ2 subunits and the GABAR synaptic anchoring protein gephyrin were essentially unaffected. We established that the α4βγ2 subunit-containing, flunitrazepam-insensitive subtype of GABARs, not normally a significant GABAR in DG neurons, was strongly upregulated instgDG, apparently arising at the expense of extrasynaptic α4βδ-containing receptors. This change was associated with a reduction in neurosteroid-sensitive GABAR-mediated tonic current. This switch in GABAR subtypes was not reciprocated in the tottering mouse model of absence epilepsy implicating a unique, intrinsic adaptation of GABAergic networks instg.

Contrary to previous reports that suggested that TARPγ2 is expressed in the dentate, we find that TARPγ2 was neither detected instgnor control DG. We report that TARPγ8 is the principal TARP isoform found in the DG and that its expression is compromised by the stargazer mutation. These effects on GABAergic parameters and TARPγ8 expression are likely to arise as a consequence of failed expression of TARPγ2 elsewhere in the brain, resulting in hyperexcitable inputs to the dentate.
Distinct Electrical and Chemical Connectivity Maps in the Thalamic Reticular Nucleus: Potential Roles in Synchronization and Sensation
Authors: Deleuze Charlotte , Huguenard John R.
Published: August 2006

GABAergic neurons of the thalamic reticular nucleus (nRt) provide thalamocortical relay neurons with feedback inhibition that influences sensory processing and thalamocortical rhythm generation. Mutual interactions between reticular neurons coordinate oscillatory activities developed within the network during normal sleep and in absence epilepsy, but the chemical versus electrical nature of these connections and their functional influence remain controversial. Here, we investigated the incidence and spatial extent of intra-nRt connectivityin vitroin horizontal and coronal thalamic slices from rat. Laser scanning photostimulation activated presynaptic nRt cells during patch-clamp recordings of postsynaptic neurons. Photolysis of caged glutamate evoked GABAergic IPSCs and/or depolarizing events (spikelets, mediated via electrical coupling) in a large proportion of neurons, thus indicating connectivity with presynaptic cell(s). Synaptic inputs were organized along the major axis of the nucleus in the same orientation as, but commonly exceeding the extent of, dendritic arborization of the postsynaptic neuron. In the anteroposterior (horizontal) plane, chemical connectivity had higher incidence (60% of recorded neurons vs 40% in vertical plane) and longer spatial extent, whereas in the dorsoventral (vertical) plane, electrical coupling dominated (47% incidence vs 37% in horizontal plane) and was more widely distributed. These data demonstrate that both electrical and chemical synapses are prominent within nRt and suggest different roles for the two types of connections. We thus propose that, along the vertical plane, electrical connectivity will promote coordinated rhythmic activity of sleep and/or thalamocortical epilepsy, whereas along the horizontal plane, chemical connectivity will oppose widespread thalamocortical synchronization and modulate sensory throughput.
Differential Effects of NMDA and AMPA Glutamate Receptors on Functional Magnetic Resonance Imaging Signals and Evoked Neuronal Activity during Forepaw Stimulation of the Rat
Authors: Gsell Willy , Burke Michael , Wiedermann Dirk , Bonvento Gilles , Silva Afonso C. , Dauphin François , Bührle Christian , Hoehn Mathias , Schwindt Wolfram
Published: August 2006

Most of the currently used methods for functional brain imaging do not visualize neuronal activity directly but rather rely on the elicited hemodynamic and/or metabolic responses. Glutamate, the major excitatory neurotransmitter, plays an important role in the neurovascular/neurometabolic coupling, but the specific mechanisms are still poorly understood. To investigate the role of the two major ionotropic glutamate receptors [NMDA receptors (NMDA-Rs) and AMPA receptors (AMPA-Rs)] for the generation of functional magnetic resonance imaging (fMRI) signals, we used fMRI [measurements of blood oxygenation level-dependent (BOLD), perfusion-weighted imaging (PWI), and cerebral blood volume (CBV)] together with recordings of somatosensory evoked potentials (SEPs) during electrical forepaw stimulation in the α-chloralose anesthetized rat. Intravenous injection of the NMDA-R antagonist MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine maleate] (0.06 mg/kg plus 3.6 μg · kg−1· h−1) significantly decreased BOLD (−51 ± 19%;n= 5) and PWI (−57 ± 26%;n= 5) responses but reduced the SEPs only mildly (approximately −10%). Systemic application of the AMPA-R antagonist GYKI-53655 [1-(4-aminophenyl)-3-methylcarbamyl-4-methyl7,8-methylenedioxy-3,4-dihydro-5H-2,3-benzodiazepine] significantly decreased both the hemodynamic response (BOLD, −49 ± 13 and −65 ± 15%; PWI, −22 ± 48 and −68 ± 4% for 5 and 7 mg/kg, i.v., respectively; CBV, −80 ± 7% for 7 mg/kg;n= 4) and the SEPs (up to −60%). These data indicate that the interaction of glutamate with its postsynaptic and/or glial receptors is necessary for the generation of blood flow and BOLD responses and illustrate the differential role of NMDA-Rs and AMPA-Rs in the signaling chain leading from increased neuronal activity to the hemodynamic response in the somatosensory cortex.
Cocaine Enhances NMDA Receptor-Mediated Currents in Ventral Tegmental Area Cells via Dopamine D5Receptor-Dependent Redistribution of NMDA Receptors
Authors: Schilström Björn , Yaka Rami , Argilli Emanuela , Suvarna Neesha , Schumann Johanna , Chen Billy T. , Carman Melissa , Singh Vineeta , Mailliard William S. , Ron Dorit , Bonci Antonello
Published: August 2006

Cocaine-induced plasticity of glutamatergic synaptic transmission in the ventral tegmental area (VTA) plays an important role in brain adaptations that promote addictive behaviors. However, the mechanisms responsible for triggering these synaptic changes are unknown. Here, we examined the effects of acute cocaine application on glutamatergic synaptic transmission in rat midbrain slices. Cocaine caused a delayed increase in NMDA receptor (NMDAR)-mediated synaptic currents in putative VTA dopamine (DA) cells. This effect was mimicked by a specific DA reuptake inhibitor and by a DA D1/D5receptor agonist. The effect of cocaine was blocked by a DA D1/D5receptor antagonist as well as by inhibitors of the cAMP/cAMP-dependent protein kinase A (PKA) pathway. Furthermore, biochemical analysis showed an increase in the immunoreactivity of the NMDAR subunits NR1 and NR2B and their redistribution to the synaptic membranes in VTA neurons. Accordingly, NMDAR-mediated EPSC decay time kinetics were significantly slower after cocaine, suggesting an increased number of NR2B-containing NMDARs. Finally, pharmacological analysis indicates that NR2B subunits might be incorporated in triheteromeric NR1/NR2A/NR2B complexes rather than in “pure” NR1/NR2B NMDA receptors. Together, our data suggest that acute cocaine increases NMDAR function in the VTA via activation of the cAMP/PKA pathway mediated by a DA D5-like receptor, leading to the insertion of NR2B-containing NMDARs in the membrane. These results provide a potential mechanism by which acute cocaine promotes synaptic plasticity of VTA neurons, which could ultimately lead to the development of addictive behaviors.
Forebrain-Specific Glutamate Receptor B Deletion Impairs Spatial Memory But Not Hippocampal Field Long-Term Potentiation
Authors: Shimshek Derya R. , Jensen Vidar , Celikel Tansu , Geng Yu , Schupp Bettina , Bus Thorsten , Mack Volker , Marx Verena , Hvalby Øivind , Seeburg Peter H. , Sprengel Rolf
Published: August 2006

We demonstrate the fundamental importance of glutamate receptor B (GluR-B) containing AMPA receptors in hippocampal function by analyzing mice with conditional GluR-B deficiency in postnatal forebrain principal neurons (GluR-BΔFb). These mice are as adults sufficiently robust to permit comparative cellular, physiological, and behavioral studies. GluR-B loss induced moderate long-term changes in the hippocampus ofGluR-BΔFbmice. Parvalbumin-expressing interneurons in the dentate gyrus and the pyramidal cells in CA3 were decreased in number, and neurogenesis in the subgranular zone was diminished. Excitatory synaptic CA3-to-CA1 transmission was reduced, although synaptic excitability, as quantified by the lowered threshold for population spike initiation, was increased compared with control mice. These changes did not alter CA3-to-CA1 long-term potentiation (LTP), which in magnitude was similar to LTP in control mice. The altered hippocampal circuitry, however, affected spatial learning inGluR-BΔFbmice. The primary source for the observed changes is most likely the AMPA receptor-mediated Ca2+signaling that appears after GluR-B depletion, because we observed similar alterations inGluR-BQFbmice in which the expression of Ca2+-permeable AMPA receptors in principal neurons was induced by postnatal activation of a Q/R-site editing-deficient GluR-B allele.
Theoretical predictions of complex formation of group-4 elements Zr, Hf, and Rf in H2SO4 solutions
Authors: Pershina Valeria , Polakova D. , Omtvedt J. P.
Published: August 2006

A process of step-wise complexation of group-4 elements Zr, Hf, and Rf in H2SO4 solutions has been considered theoretically. Relative values of the free energy change of the M(SO4)2(H2O)4, M(SO4)3(H2O)2
2− and M(SO4)4
4− (M = Zr, Hf, and Rf) formation reactions from hydrated and partially hydrolyzed cations have been calculated using the fully relativistic density functional theory method. They proved to be very similar for reactions of Zr and Hf. At low H2SO4 concentrations, Hf should, however, have a slight preference for the complex formation, especially, when hydrolysis takes place, while with increasing H2SO4 concentration and decreasing hydrolysis, the trend should be Zr > Hf. According to the results, Rf should exhibit a weaker tendency to complex formation than Zr and Hf at the entire range of acid concentrations, i.e., for all types of complexes. Thus, the predicted trend is Zr > Hf ≫ Rf. The same trend is also found for the formation of R4M(SO4)4, where R is a monovalent cation. Accordingly, the trend in the K
d (distribution coefficient) values in anion-exchange separations of group-4 elements should be: Zr > Hf ≫ Rf. The obtained trend for Zr and Hf is in agreement with literature data on extraction of these elements in macro-concentrations from sulphuric acid solutions and with recent experiments on extraction of single species by TOA in toluene using the SISAK technique.
Simplified, automated synthesis of 3′[18F]fluoro-3′-deoxy-thymidine ([18F]FLT) and simple method for metabolite analysis in plasma
Authors: Reischl G. , Blocher Achim , Wei Rongqing , Ehrlichmann Walter , Kuntzsch Matthias , Solbach Christoph , Dohmen Bernhard M. , Machulla Hans-Jürgen
Published: August 2006

3′[18F]Fluoro-3′-deoxy-thymidine ([18F]FLT) (III) has been discussed to be a promising tracer for assessing tumor proliferation. In order to perform clinical studies for evaluating [18F]FLT a simplified labeling procedure was developed using 2,3′-anhydrothymidine with benzoyl as a protecting group in the 5′-position (I). In DMSO the labeling yield was 46% at 160 °C in 10 min. Hydrolysis was efficiently performed with 0.25% NaOH at room temperature within 10 min. The labeling procedure was transferred to a remote controlled synthesis module allowing the production of [18F]FLT in high activities. The overall radiochemical yield was 18.1 ± 5.4% (n= 55) with absolute yields of 9.2 ± 2.6 GBq of [18F]FLT at EOS ready for injection (60 min after EOB; irradiation parameters: 35 μA, 60 min) and specific activities of 100–220 GBq/μmol. A convenient cartridge method for metabolite analysis was developed and validatedversusHPLC showing that after 90 min 69.0 ± 7.0% of the radioactivity in plasma (less than 20% of initial radioactivity) was unchanged [18F]FLT (26 patients with various tumors).
Substoichiometric extraction of iron by 2-methyloxine inton-butanol
Authors: Mandal M. , Pal D. , Basu S.
Published: August 2006

Determination of iron(III) by substoichiometric extraction with 2-methyloxine inton-butanol is being reported. The method has been applied for the determination of the metal in several analyzed samples like Mn-bronze, Al-bronze and dolomite.
Determination of stability constants of lanthanide nitrate complex formation using a solvent extraction technique
Authors: Andersson Sofie , Eberhardt Klaus , Ekberg Christian , Liljenzin Jan-Olov , Nilsson Mikael , Skarnemark Gunnar
Published: August 2006

For lanthanides and actinides, nitrate complex formation is an important factor with respect to the reprocessing of nuclear fuels and in studies that treat partitioning and transmutation/conditioning. Different techniques, including microcalorimetry, various kinds of spectroscopy, ion-exchange and solvent extraction, can be used to determine stability constants of nitrate complex formation. However, it is uncommon that all lanthanides are studied at the same time, using the same experimental conditions and technique. The strengths of the complexes are different for lanthanides and actinides, a feature that may assist in the separation of the two groups. This paper deals with nitrate complex formation of lanthanides using a solvent extraction technique. Trace amounts of radioactive isotopes of lanthanides were produced at the TRIGA Mainz research reactor and at the Institutt for Energiteknikk in Kjeller, Norway (JEEP II reactor).

The extraction of lanthanide ions into an organic phase consisting of 2,6-bis-(benzoxazolyl)-4-dodecyloxylpyridine, 2-bromodecanoic acid and tert-butyl benzene as a function of nitrate ion concentration in the aqueous phase was studied in order to estimate the stability constants of nitrate complex formation. When the nitrate ion concentration is increased in the aqueous phase, the nitrate complex formation starts to compete with the extraction of metal ions. Thus the stability constants of nitrate complex formation can be estimated by measuring the decrease in extraction and successive fitting of an appropriate model.

Extraction curves for La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Dy, Ho and Er were obtained and stability constants for their nitrate complex formation were estimated. Tb, Tm, Yb and Lu were also investigated, but no stability constants could be determined. The distribution ratios for the metal ions at low nitrate ion concentration were obtained at the same time, showing the effect of lanthanide contraction resulting in decreasing extraction along the series. A clear tetrad effect in the lanthanide group was also found.
A simplified reaction model predicting the effect of some parameters on the degradation of phenol in the electron beam process
Authors: Pellizzari Fabien , Follut Florian , Karpel Vel Leitner Nathalie
Published: August 2006

Electron beam irradiation is a known advanced oxidation process that is studied in the literature to examine the possibilities of pollutant removal from waters. In the present work, a common pollutant, phenol, was chosen as model molecule to investigate the capability of a simple reaction system to predict the influence of certain parameters on the efficiency of the electron beam process. This model is based on the main reactions occurring during the irradiation of aqueous solutions of phenol. It was found to simulate suitably the effect of the dissolved oxygen and of the initial concentration on the abatement of the molecule during the irradiation.

Various irradiation experiments were also performed by modifying the mode of the dose deposition. The results showed that, for a given applied dose, the multiplication of the passages under the electron beam significantly improves the abatement of phenol (20%). The oxygenation of the solution and the mathematical expression of the evolution of the pollutant concentration with the radiation dose partly explain this improvement.
Plasma dipeptidyl peptidase-IV activity in patients with type-2 diabetes mellitus correlates positively with HbAlc levels, but is not acutely affected by food intake
Authors: Ryskjær Jakob , Deacon Carolyn F , Carr Richard D , Krarup Thure , Madsbad Sten , Holst Jens , Vilsbøll Tina
Published: August 2006

Objective: Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide are incretin hormones, secreted in response to meal ingestion. The incretin hormones stimulate insulin secretion and are essential for the maintenance of normal plasma glucose concentrations. Both incretin hormones are metabolized quickly by the enzyme dipeptidyl peptidase-IV (DPP-IV). It is well known that type-2 diabetic patients have an impaired incretin effect. Therefore, the aim of the present study was to investigate plasma DPP-IV activity in the fasting and the postprandial state in type-2 diabetic patients and control subjects.

Design: The study included two protocols. Protocol one involved 40 fasting type-2 diabetic patients (28 men); age 61 ± 1.4 (mean ± s.e.m.) years; body mass index (BMI) 31 ± 0.6 kg/m2; HbAlc 7.2 ± 0.2%; and 20 matched control subjects (14 men) were studied. Protocol two involved eight type-2 diabetic patients (six men); age 63 ± 1.2 years; BMI 33 ± 0.5 kg/m2; HbAlc 7.5 ± 0.4%; eight matched control subjects were included.

Methods: In protocol one, fasting values of DPP-IV activity were evaluated and in protocol two, postprandial DPP-IV activity during a standard meal test (566 kcal) was estimated.

Results: Mean fasting plasma DPP-IV activity (expressed as degradation of GLP-1) was significantly higher in this patient group compared with the control subjects (67.5 ± 1.9 vs 56.8 ± 2.2 fmol GLP-1/h (mean ± s.e.m.); P=0.001). In the type-2 diabetic patients, DPP-IV activity was positively correlated to FPG and HbAlc and negatively to the duration of diabetes and age of the patients. No postprandial changes were seen in plasma DPP-IV activity in any of the groups.

Conclusions: Plasma DPP-IVactivity increases in the fasting state and is positively correlated to FPG and HbAlc levels, but plasma DPP-IV activity is not altered following meal ingestion and acute changes in plasma glucose.
Normative data for adiponectin, resistin, interleukin 6, and leptin/receptor ratio in a healthy Spanish pediatric population: relationship with sex steroids
Authors: Martos-Moreno Gabriel Á , Barrios Vicente , Argente Jesús
Published: August 2006

Objectives: To investigate the circulating levels of adiponectin, resistin, interleukin 6 (IL-6), and leptin/receptor ratio in healthy Spanish children throughout the different stages of pubertal development. To analyze the relationship between adipokines and sex steroid level changes during puberty.

Study design: Serum adiponectin, resistin, IL-6 levels, and leptin/receptor ratio were studied in 160 healthy Spanish children grouped according to their pubertal stage (Tanner I, 23 girls and 22 boys; Tanner II, 19 girls and 16 boys; Tanners III and IV, 21 girls and 20 boys; and Tanner V, 20 girls and 19 boys). In addition, circulating levels of sex hormone-binding globulin (SHBG) were determined in every subject, and testosterone and estradiol levels in boys and girls respectively.

Results: Adiponectin levels decreased in boys from mid puberty (P < 0.05) to become significantly lower than in girls (P < 0.001), whereas IL-6 decreased in both sexes (P < 0.05). Resistin levels and leptin/receptor ratio showed no differences between sexes or according to pubertal stage, except in adult females, who had the highest levels of both parameters (P < 0.001). Serum IL-6 levels correlated significantly (P < 0.05) with testosterone and estradiol levels (r=−0.37 and −0.42 respectively), whereas estradiol, but not testosterone, correlated with leptin/receptor ratio (r=0.59; P < 0.001). Furthermore, a positive relationship was found between SHBG and adiponectin and IL-6 (P < 0.001 and P < 0.05 respectively). In addition, a direct correlation between leptin/receptor and body mass index was found in both sexes (P < 0.001).

Conclusion: Variations in adipokine profiles throughout pubertal development appear to be related with progression of gonadal function.
Adiponutrin gene is regulated by insulin and glucose in human adipose tissue
Authors: Moldes Marthe , Beauregard Geneviève , Faraj May , Peretti Noël , Ducluzeau Pierre-Henri , Laville Martine , Rabasa-Lhoret Rémi , Vidal Hubert , Clément Karine
Published: August 2006

Objective: Adiponutrin is a new transmembrane protein specifically expressed in adipose tissue. In obese subjects, short- or long-term calorie restriction diets were associated with a reduction in adiponutrin gene expression. Adiponut.rin mRNA level was previously shown to be negatively correlated with fasting glucose plasma levels and associated with insulin sensitivity of non-diabetic obese and non-obese subjects. The purpose of the present work was to get more insight into the regulation of adiponutrin gene expression by insulin and/or glucose using clamp studies and to examine its potential dysregulation in subjects with a deterioration of glucose homeostasis.

Methods: Adiponutrin gene expression was quantified by reverse transcriptase-quantitative PCR in s.c. adipose tissue of healthy lean subjects after an euglycemic hyperinsulinemic clamp (EGHI), a hyperglycemic euinsulinemic clamp, and a hyperglycemic hyperinsulinemic (HGHI) clamp. Adiponutrin gene expression was also analyzed in patients with different levels of insulin resistance.

Results: During EGHI, insulin infusion induced adiponutrin gene expression 8.4-fold (P = 0.008). Its expression was also induced by glucose infusion, although to a lesser extend (2.2-fold, P = 0.03). Infusion of both insulin and glucose (HGHI) had an additive effect on the adiponutrin expression (tenfold, P = 0.008). In a pathological context, adiponutrin gene was highly expressed in the adipose tissue of type-1 diabetic patients with chronic hyperglycemia compared with healthy subjects. Conversely, adiponutrin gene expression was significantly reduced in type-2 diabetics (P = 0.01), but remained moderately regulated in these patients after the EGHI clamp (2.5-fold increased).

Conclusion: These results suggest a strong relationship between adiponutrin expression, insulin sensitivity, and glucose metabolism in human adipose tissue.
Effects of environmental temperature on thyroid hormones in the barn owl (Tyto alba)
Authors: Klein Á. , Kulcsár Margit , Krízsik Virág , Mátics R. , Rudas P. , Török J. , Huszenicza Gy.
Published: August 2006

The basic patterns of thyroid hormones [thyroxine (T4) and 3,3',5-triiodothyronine (T3)] and the T4 and T3 responses induced by thyrotropin releasing hormone (TRH) are reported in captive female barn owls (Tyto alba) during the non-breeding period. The main findings of the study, conducted on a total of 10 owls, are as follow: (1) The thyroid gland of barn owl can be stimulated by the classical TRH stimulation test. (2) T3 response was much more pronounced both under cold (around 10°C) and warm (around 20°C) conditions, whereas T4 response ranged so widely that we could not point out any significant change in it. (3) Basal T3 plasma level was significantly (p = 0.036) higher in birds exposed to cold temperature, and they responded to TRH treatment with a lower plasma T3 elevation than the birds kept in a warm chamber. This pattern, however, cannot be explained by increased food intake, but is in agreement with the fact that enhanced T3 level may account for higher avUCP mRNA expression, which results in higher heat production on the cell level. From the results it is concluded that altering T3 plasma level plays a significant role in cold-induced thermoregulation.